A control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that the lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid further undesirable rotation of the power tool. The controller may opt to reduce the torque applied to shaft to a non-zero value that enables the operator to regain control of the tool.

Patent
   RE44993
Priority
Oct 20 2004
Filed
Aug 31 2012
Issued
Jul 08 2014
Expiry
Oct 19 2025
Assg.orig
Entity
Large
9
334
all paid
0. 16. A method for calibrating a power tool having a rotational rate sensor, comprising:
mounting the power tool to a test fixture, the power tool having a rotary shaft and a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft;
rotating the power tool at a known angular velocity about the longitudinal axis using the test fixture;
measuring, by the rotational rate sensor, an angular velocity of the power tool rotating about the longitudinal axis; and
computing a first difference between the measured angular velocity and the known angular velocity.
0. 22. A method for calibrating a power tool having a rotary shaft, comprising:
removing a test module from the power tool, the test module detachably couples to the power tool and houses a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft;
mounting the test module to a test fixture;
rotating the test module at a known angular velocity about the longitudinal axis using the test fixture;
measuring, the rotational rate sensor, an angular velocity of the test module rotating about the longitudinal axis; and
computing a first difference between the measured angular velocity and the known angular velocity.
0. 28. A method for operating a power tool having a rotational rate sensor, comprising:
mounting the power tool to a test fixture, the power tool having a rotary shaft and a rotational rate sensor configured to detect rotational motion of the power tool about a longitudinal axis of the rotary shaft;
rotating the power tool at a known angular velocity about the longitudinal axis using the test fixture;
measuring, by the rotational rate sensor, an angular velocity of the power tool rotating about the longitudinal axis;
computing a difference between the measured angular velocity and the known angular velocity;
storing the difference in a memory of the power tool
monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool;
computing angular displacement of the power tool about the axis of the rotary shaft using a controller disposed in the power tool, the computation being based on input from the rotational motion sensor and the difference in the memory;
initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and
initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements.
0. 1. A method for initiating a protective response in a power tool having a rotary shaft, comprising:
monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool;
computing angular displacement of the power tool about the axis of the rotary shaft using a controller disposed in the power tool and based on input from the rotational motion sensor;
initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and
initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements.
0. 2. The method of claim 1 further comprises initiating a protective operation when angular velocity of the power tool about the axis exceeds a velocity threshold and the angular displacement of the power tool falls within the range of angular displacements.
0. 3. The method of claim 1 further comprises initiating a protective operation when angular displacement of the power tool falls within a range of angular displacements and angular acceleration of the power tool about the axis exceeds an acceleration threshold.
0. 4. The method of claim 1 further comprises arranging the rotational motion sensor at a location in the power tool spatially separated from the rotary shaft.
0. 5. The method of claim 1 further comprises employing a rotational motion sensor that measures rotational velocity based on Coriolis acceleration.
0. 6. The method of claim 1 wherein the protective operation when angular displacement of the power tool falls within a range of angular displacements is different than the protective operation when angular displacement of the power tool exceeds the range of angular displacements.
0. 7. The method of claim 1 wherein the protective operation is selected from the group consisting of pulsing a motor of the power tool, braking the rotary shaft, braking the motor, disengaging the motor from the rotary shaft, discontinuing power delivered to the motor and reducing slip torque of a clutch disposed between the motor and the rotary shaft.
0. 8. A method for initiating a protective response in a power tool having a motor drivably coupled to a rotary shaft to impart rotary motion thereto, comprising:
monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool;
determining angular displacement of the power tool about the axis of the rotary shaft from a baseline using a controller disposed in the power tool and based on input from the rotational motion sensor;
initiating a protective operation in the power tool by the controller when a first operating condition of the power tool exceeds a first operating threshold and angular displacement of the power tool falls within a first range of angular displacements; and
initiating a protective operation in the power tool by the controller when a second operating condition of the power tool exceeds a second operating threshold and angular displacement of the power tool falls within a second range of angular displacements, where the second operating condition is different than the first operating condition and the second range of angular displacements is mutually exclusive of the first range of angular displacements.
0. 9. The method of claim 8 further comprises initiating a protective operation when angular velocity of the power tool about the axis exceeds a velocity threshold and angular displacement of the power tool falls within the first range of angular displacements.
0. 10. The method of claim 9 further comprises initiating a protective operation when angular velocity of the power tool is less than the velocity threshold and angular displacement of the power tool falls within the second range of angular displacements.
0. 11. The method of claim 8 further comprises arranging the rotational motion sensor at a location in the power tool spatially separated from the rotary shaft.
0. 12. The method of claim 8 further comprises employing a rotational motion sensor that measures rotational velocity based on Coriolis acceleration.
0. 13. The method of claim 8 further comprises periodically resetting the baseline when angular velocity of the power tool about the axis is less than a velocity threshold.
0. 14. The method of claim 8 wherein the protective operation is selected from the group consisting of pulsing a motor of the power tool, braking the rotary shaft, braking the motor, disengaging the motor from the rotary shaft, discontinuing power delivered to the motor and reducing slip torque of a clutch disposed between the motor and the rotary shaft.
0. 15. A method for initiating a protective response in a power tool having a rotary shaft, comprising:
monitoring rotational motion of the power tool about a longitudinal axis of the rotary shaft using a rotational motion sensor disposed in the power tool;
computing angular displacement of the power tool about the axis of the rotary shaft from a baseline using a controller disposed in the power tool and based on input from the rotational motion sensor;
periodically resetting the baseline when angular velocity of the power tool about the axis is less than a velocity threshold;
initiating a protective operation by the controller when an operating condition of the power tool exceeds a threshold and the angular displacement of the power tool falls within a range of angular displacements; and
initiating a protective operation by the controller when the operating condition of the power tool is less than the threshold but the angular displacement of the power tool exceeds the range of angular displacements.
0. 17. The method of claim 16 further comprises measuring output of the rotational rate sensor when the power tool is stationary on the test fixture to obtain an offset calibration value.
0. 18. The method of claim 16 further comprises
adjusting the angular velocity measured by the rotational rate sensor using the difference; and
comparing the adjusted angular velocity to the known angular velocity to verify calibration of the tool.
0. 19. The method of claim 16 further comprises
rotating the power tool at the known angular velocity in an opposite direction about the longitudinal axis using the test fixture;
measuring, by the rotational rate sensor, an angular velocity of the power tool rotating in the opposite direction about the longitudinal axis; and
computing a second difference between the measured angular velocity and the known angular velocity.
0. 20. The method of claim 16 further comprises measuring angular velocity based on Coriolis acceleration.
0. 21. The method of claim 16 further comprises
storing the differences in a memory of the power tool;
removing the power tool from the test fixture; and
adjusting, during operation of the power tool, output reported by the rotational rate sensor using the difference values.
0. 23. The method of claim 22 further comprises measuring output of the rotational rate sensor when the test module is stationary on the test fixture to obtain an offset calibration value.
0. 24. The method of claim 22 further comprises
adjusting the angular velocity measured by the rotational rate sensor using the difference; and
comparing the adjusted angular velocity to the known angular velocity to verify calibration of the tool.
0. 25. The method of claim 22 further comprises
rotating the test module at a known angular velocity in an opposite direction about the axis using the test fixture;
measuring, by the rotational rate sensor, an angular velocity of the test module rotating in the opposite direction about the longitudinal axis; and
computing a second difference between the measured angular velocity and the known angular velocity.
0. 26. The method of claim 22 further comprises measuring angular velocity based on Coriolis acceleration.
0. 27. The method of claim 26 further comprises
storing the first and second differences in a memory of the test module;
removing the test module from the test fixture;
re-installing the test module in the power tool; and
adjusting, during operation of the power tool, output reported by the rotational rate sensor using the first and second differences.

This application is a continuation reissue of U.S. Ser. No. 13/423,736, filed Mar. 19, 2012 which is a reissue of U.S. Pat. No. 7,681,659 issued Mar. 23, 2010 which is a continuation of U.S. patent application Ser. No. 11/519,427 filed on Sep. 12, 2006, now U.S. Pat. No. 7,552,781 issued Jun. 30, 2009 which in turn is a continuation-in-part of U.S. patent application No. 11/254,146 filed on Oct. 19, 2005, now U.S. Pat. No. 7,410,006 issued Aug. 12, 2008 which claims benefit of U.S. Provisional Application No. 60/620,283, filed on Oct. 20, 2004 and U.S. Provisional Application No. 60/675,692 filed on Apr. 28, 2005,. The disclosure disclosures of the above applications is are incorporated herein by reference. More than one reissue application has been filed for the reissue of U.S. Pat. No. 7,681,659. The reissue applications are application Ser. Nos. 13/600,722 (the present application), 13/423,736 and 13/600,927, all of which are continuation reissues of U.S. Pat. No. 7,681,659.

The disclosure relates generally to power tools and, more particularly, to a control system having a rotational rate sensor for detecting the onset of a rotational condition in a power tool.

Power tools typically employ a motor that imparts torque to a tool through a spindle. In the case of an electric drill, the motor spindle is coupled through a series of reducing gears to the chuck, which in turn holds the drill bit or other cutting/abrading tool, such as a hole saw, a grinding wheel or the like. Power screwdrivers as well a large rotary hammers work on a similar principle. In each of these cases, the function of the reducing gears or gear train is to reduce the rotational speed of the tool while increasing the rotational torque.

Power routers are somewhat different. The cutting tool of the hand-held router is typically direct coupled to the spindle of the motor. In this case, the full rotational speed of the motor is used without gear reduction to rotate the router bit at high speed. Reciprocating saw and jigsaws use yet another type of gear train that translates the rotational motion of the motor spindle to reciprocating movement.

Generally speaking, all of these power tools may suddenly encounter an impending kickback condition at which time the output torque rapidly rises because of local changes in workpiece hardness, workpiece binding, tool obstruction from burrs and so forth. For example, when drilling a hole with a power drill, some workpieces will develop burrs on the tool exit side of the workpiece. These burrs can engage the flutes of the drill bit, thereby causing a rapid increase in torque as the drill tries to break free. In some instances, the burrs may stop drill bit rotation, thereby causing a strong reaction torque that is imparted to the tool operator as the motor turns the tool in the operator's grasp (rather than turning the drill bit). This reaction is can be problematic if the operator is standing on a ladder and/or holding the tool over their head. A related phenomenon also occurs with power saws. These conditions are hereinafter generally referred to as kickback conditions, regardless of the particular power tool involved or the specific circumstance which give rise to the condition.

Therefore, it is desirable to provide an improved technique for detecting the onset of such kickback conditions in power tools. The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

In one aspect of the disclosure, a control system is provided for use in a power tool. The control system includes: a rotational rate sensor having a resonating mass and a controller electrically connected to the rotational rate sensor. The rotational rate sensor detects lateral displacement of the resonating mass and generates a signal indicative of the detected lateral displacement, such that lateral displacement is directly proportional to a rotational speed at which the power tool rotates about an axis of the rotary shaft. Based on the generated signal, the controller initiates a protective operation to avoid undesirable rotation of the power tool.

In another aspect of the disclosure, the control scheme employed by the power tool may initiate different protective operations for different tool conditions.

In different aspect of the disclosure, the control scheme may initiate a protective operations based on input from two different sensors.

In yet another aspect of the disclosure, the control scheme employed by the power tool may initiate protective operations based on the rotational energy experienced by the tool.

For a more complete understanding of the invention, its objects and advantages, reference may be made to the following specification and to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of an exemplary rotary hammer configured in accordance with the present disclosure;

FIG. 2 is simplified block diagram of an exemplary control system in accordance with present disclosure;

FIG. 3 is a flowchart illustrating an exemplary method for determining the onset of a kickback condition according to the present disclosure;

FIGS. 4A and 4B are flowcharts illustrating an exemplary method for determining a kickback condition based on angular displacement according to the present disclosure;

FIG. 5 is a flowchart illustrating an exemplary method for determining a kickback condition based input from two different sensors according to the present disclosure;

FIG. 6 is a block diagram of another exemplary control system in accordance with the present disclosure;

FIG. 7 depicts an exemplary look-up table which may be used by the control system;

FIG. 8 illustrates an exemplary calibration system for a power tool configured with the control system; and

FIG. 9 illustrates an exemplary calibration procedure which may be employed by the control system.

The drawing described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 illustrates an exemplary power tool 10 having a rotary shaft. In this example, the power tool is a hand held rotary hammer. While the following description is provided with reference to a rotary hammer, it is readily understood that the broader aspects of this disclosure are applicable to other types of power tools having rotary shafts, such as drills, circular saws, angle grinders, screw drivers and polishers.

In general, the rotary hammer includes a spindle 12 (i.e., a rotary shaft) drivably coupled to an electric motor 14. A chuck 16 is coupled at one end of the spindle 12; whereas a drive shaft 18 of the electric motor 14 is connected via a transmission 22 to the other end of the spindle 12. These components are enclosed within a housing 18. Operation of the tool is controlled through the use an operator actuated switch 24 embedded in the handle of the tool. The switch regulates current flow from a power supply 26 to the motor 14. The power tool may further include a temperature sensor 27. Although a few primary components of the rotary hammer are discussed above, it is readily understood that other components known in the art may be needed to construct an operational rotary hammer.

The power tool 10 is further configured with a control system 30 for detecting and preventing torque conditions which may cause the operator to lose control of the tool. The control system 30 may include a rotational rate sensor 32, a current sensor 34, and a microcontroller 36 embedded in the handle of the power tool 10. Under certain operating conditions, the power tool 10 may rotate in the operator's grasp. In a rotary hammer, the rotational rate sensor 32 is configured to detect rotational motion of the tool about the longitudinal axis of the spindle 12. The rotational rate sensor 32 in turn communicates a signal indicative of any rotational motion to the controller 36 for further assessment. For different power tools, it is envisioned that the sensor may be disposed in a different location and/or configured to detect motion along a different axis.

In a preferred embodiment, the operating principle of the rotational rate sensor 32 is based on the Coriolis effect. Briefly, the rotational rate sensor is comprised of a resonating mass. When the power tool is subject to rotational motion about the axis of the spindle, the resonating mass will be laterally displaced in accordance with the Coriolis effect, such that the lateral displacement is directly proportional to the angular rate. It is noteworthy that the resonating motion of the mass and the lateral movement of the mass occur in a plane which is orientated perpendicular to the rotational axis of the rotary shaft. Capacitive sensing elements are then used to detect the lateral displacement and generate an applicable signal indicative of the lateral displacement. An exemplary rotational rate sensor is the ADXRS150 or ADXRS300 gyroscope device commercially available from Analog Devices. Other types of rotational sensors, such as angular speed sensors, accelerometers, etc., are also within the scope of this disclosure.

The microcontroller 36 assesses the rotational motion of the tool to detect rotational conditions which may cause the operator to lose control of the tool. Upon detecting an unacceptable rotational condition, the microcontroller 36 will initiate a protective operation intended to minimize and/or avoid any undesired rotation of the power tool. For instance, when the angular velocity of the tool exceeds some empirically derived threshold, the microcontroller may cut power to the motor. A few exemplary techniques for assessing the rotational condition of the tool are further described below. It is readily understood that other techniques for assessing the rotational condition of the tool are also within the scope of this disclosure.

Operation of an exemplary control circuit 40 is further described below in relation to FIG. 2. A power supply circuit 29 is coupled to an AC power line input and supplies DC voltage to operate the microcontroller 36′. The trigger switch 24′ supplies a trigger signal to the microcontroller 36′ which indicates the position or setting of the trigger switch 24′ as it is manually operated by the power tool operator. Drive current for operating the motor 14′ is controlled by a triac drive circuit 42. The triac drive circuit 42 is, in turn, controlled by a signal supplied by microcontroller 36′. If desired, the control system 30′ may include a reset circuit 44 which, when activated, causes the microcontroller 36′ to be re-initialized.

The microcontroller 36′ is also supplied with a signal from a current detector circuit 48. The current detector circuit 48 is coupled to the triac drive circuit 42 and supplies a signal indicative of the conductive state of the triac drive circuit 42. If for some reason the triac drive circuit 42 does not turn on in response to the control signal from the microcontroller 36′, this condition is detected by the current detector circuit 48.

A current sensor 34′ is connected in series with the triac drive circuit 42 and the motor 14′. In an exemplary embodiment, the current sensor 34′ may be a low resistance, high wattage resistor. The voltage drop across the current sensor 34′ is measured as an indication of actual instantaneous motor current. The instantaneous motor current is supplied to an average current measuring circuit 46 which in turn supplies the average current value to the microcontroller 36′. The microcontroller 36′ may use the average current to evaluate the rotational condition of the tool.

In operation, the trigger switch 24′ supplies a trigger signal that varies in proportion to the switch setting to the microcontroller 36′. Based on this trigger signal, the microcontroller 36′ generates a control signal which causes the triac drive circuit 42 to conduct, thereby allowing the motor 14′ to draw current. Motor torque is substantially proportional to the current drawn by the motor and the current draw is controlled by the control signal sent from the microcontroller to the triac drive circuit 42. Thus, the microcontroller 36′ can control the torque imparted by the motor.

Pulse mode is an exemplary protective operation which may be initiated upon detecting a kickback condition. Upon detecting the onset of a kickback condition, the microcontroller 36′ may operate the motor 14′ in a pulse mode. During pulse mode, the motor current is pulsed at a predetermined frequency with a predetermined on-time. In one exemplary embodiment, the series of current pulses is designed such that the operator may regain control of a twisting tool. For example, the time between pulses may be set between 0.1 and 1 second. Alternatively, the series of current pulses create torque pulses that may have a peak torque that is greater than the average torque delivered by the spindle 12. In this way, the torque pulses may allow the tool 10 to break through the burrs or workpiece restrictions that are causing the impending kickback condition. Further details regarding this protection operation may be found in U.S. Pat. No. 6,479,958 which is incorporated herein by reference.

Another exemplary protective operation is to reduce the torque imparted to the spindle to a non-zero value that enables an operator of the tool to regain control of the tool. In the context of the control circuit 40 described above, the controller can override the trigger signal from the trigger switch or other operator input commands. Upon detecting a triggering rotational condition, the controller 36′ sends a control signal to the triac drive circuit 46′ which reduces the voltage which in turn reduces the current draw of the motor, thereby reducing the torque imparted to the spindle. For example, the torque could be reduced to 30% of its current operational amount or a predefined fixed torque level. The tool would operate at his reduced level until the operator released the trigger switch and re-engaged it or cycled tool power. Another method would involve resetting torque to its original operation level if the operator regains control of the tool. In this way, the operator has regained control of the tool without terminating or resetting operation of the tool.

Other techniques for reducing the torque imparted to the spindle are also within the scope of this disclosure. For example, DC operated motors are often controlled by pulse width modulation, where the duty cycle of the modulation is proportional the speed of the motor and thus the torque imparted by the motor to the spindle. In this example, the microcontroller may be configured to control the duty cycle of the motor control signal.

Alternatively, the power tool may be configured with a torque transmitting device interposed between the motor and the spindle. In this case, the controller may interface with the torque transmitting device to reduce torque. The torque transmitting device may take the form of a magneto-rheologocical fluid clutch which can vary the torque output proportional to the current fed through a magnetic field generating coil. It could also take the form of a friction plate, cone clutch or wrap spring clutch which can have variable levels of slippage based on a preload holding the friction materials together and thus transmitting torque. In this example, the preload could be changed by driving a lead screw supporting the ground end of the spring through a motor, solenoid or other type of electromechanical actuator. Other types of torque transmitting devices are also contemplated by this disclosure.

In other instances, the protective operation is intended to terminate or reset operation of the tool. Exemplary protective operations of this nature include (but are not limited to) disengaging the motor 14′ from the spindle 12, braking the motor 14′, braking the spindle 12, and disconnecting power to the motor 14′. Depending on the size and orientation of the tool 10, one or more of these protective operations may be initiated to prevent undesirable rotation of the tool 10.

An exemplary method for detecting a rotational condition of the tool is illustrated in FIG. 3. First, the operator switch is checked at step 52 to determine if the tool is operating. If the switch is not closed, then power is not being supplied to the motor as indicated at 53. In this case, there is no need to monitor for kickback conditions. Conversely, if the switch is closed, then power is being supplied to the motor as indicated at 54.

During tool operation, rotational motion of the tool is monitored at 56 based on the signal from the rotational rate sensor. When the rotational rate of the tool exceeds some empirically derived threshold (as shown at 57), this may indicate the onset of kickback condition; otherwise, processing control returns to the beginning of the algorithm. In addition to rotational rate of the tool about its spindle axis, it is envisioned that the rotational displacement, rotational acceleration, or some combination thereof as derived from the sensor signal may be used to determine the onset of a kickback condition.

Prior to initiating some protective operation, the microcontroller also evaluates the current draw of the motor at 58. Specifically, the rate of change of the motor current is measured. When the rate of change is positive and exceeds some predetermined threshold, then one or more protective operations are initiated at 60. If either the rate of change is not positive or the rate of change does not exceeds the threshold, then processing control returns to the beginning of the algorithm. In this case, a sudden change in the current draw is optionally used to confirm the onset of the kickback condition. It is envisioned that inputs from other sensors, such as a temperature sensor, may be used in a similar manner. It is to be understood that only the relevant steps of the control scheme are discussed above, but that other software-implemented instructions may be needed to control and manage the overall operation of the tool.

In another aspect of the present invention, the control scheme employed by the power tool 10 may initiate different protective operations for different tool conditions. For example, the amount of angular displacement experienced by the tool may dictate different protective operations. When angular displacement is within a first range (e.g., less than 31°), the operator is presumed to have control of the tool and thus no protective operations are needed. When the angular displacement exceeds this first range, it may be presumed that the tool has encountered a kickback condition and therefore some protective operation may be needed. In this second range of angular displacement (e.g., between 30° to 90°), the control scheme may initiate a pulse mode in hope of breaking through the restrictions that are causing the impending kickback condition. In contrast, when the angular displacement exceeds the second range (e.g., greater than 90°), it may be presumed that the operator has lost control of the tool. In this instance, a different protective operation may be initiated by the control scheme, such as disconnecting the power to the motor.

Depending on the complexity of the control scheme, three or more ranges of displacement may be defined for a given power tool. Within a range, protective operations may be initiated based on the angular displacement or a combination of parameters, such as angular acceleration, angular velocity, motor current, rate of change of motor current, motor temperature, switch temperature, etc. It is readily understood that the number and size of the ranges may vary for different control schemes and/or different types of tools. It is also envisioned that different protective operations may be initiated based on ranges of other parameters (e.g., ranges of angular velocity). Likewise, one or more protective operations may be associated with different ranges (i.e., tool conditions).

An exemplary method for detecting a rotational condition based on an angular displacement of the power tool is further described below in relation to FIGS. 4A and 4B. During tool operation, angular displacement is monitored in relation to a start point (θ0). In step 61, this starting point is initialized to zero. Any subsequent angular displacement of the tool is then measured in relation to this reference. Alternatively, the tool may employ a starting point reset function. At power-up, the starting point is set. If the operator repositions the tool (e.g., rotate it at a very slow rate), then the starting point is reset. For example, if the tool is rotated at a rate less than 5 degree per second, then the starting position is reset. Angular displacement is then measured from the new starting point.

Angular displacement of the tool is then monitored at step 62. In this exemplary embodiment, the angular displacement is measured in relation to the reference value (θ0) and derived from the rate of angular displacement over time or angular velocity (ωTOOL) as provided by a rotational rate sensor. While the rotational rate sensor described above is presently preferred for determining angular displacement of the tool, it is readily understood that this additional aspect of the present invention is not limited to this type of sensor. On the contrary, angular displacement may be derived from a different type of rotational rate sensor, an acceleration sensor or some other manner for detecting rotational displacement of the tool.

Different protective operations may be initiated based on the amount of angular displacement as noted above. Angular displacement is assessed at steps 64 and 68. When the angular displacement exceeds some upper threshold (θzone2min), then a first protective operation is initiated at step 66. In this example, power to the motor is disconnected, thereby terminating operation of the tool.

When the angular displacement exceeds some lower threshold (θzone1min), then a different protective operation, such as pulsing the motor current, may be initiated at 70. In this exemplary embodiment, an instantaneous measure of angular velocity must also exceed some minimum threshold before a pulse mode is initiated as shown at step 69. If neither of these criteria are met, no protective actions are taken and operating conditions of tool continue to be monitored by the control scheme.

During pulse mode, the control scheme continues to monitor tool operating conditions. Hazardous conditions may be monitored as shown at step 72. For instance, to prevent motor burn up, motor current may be monitored. If the motor current spikes above some predefined threshold, then power to the motor is disconnected at 73. To protect the tool operator, angular displacement may also be monitored. If angular displacement exceeds a threshold indicative of lost control, then the power to the motor is also disconnected. It is readily understood that other types of hazardous conditions may be monitored.

In addition, pulse mode is only maintained for a brief period of time. A timer is initiated at step 71 and pulse mode continues until the timer has expired as shown at 76. During this time, the control scheme may also monitor if the restrictions that caused the kickback condition have been overcome as shown at step 74. If the restrictions are overcome, then pulse mode is discontinued at step 75. When the timer expires without overcoming the restrictions, then power to the motor is disconnected as shown at 77.

An exemplary method for detecting a rotational condition based on input from at least two sensors is described below in relation to FIG. 5. First, the operator switch is checked at step 82 to determine if the tool is operating. If the switch is not closed, then power is not being supplied to the motor as indicated at 83. In this case, there is no need to monitor for kickback conditions. Conversely, if the switch is closed, then power is being supplied to the motor as indicated at 84.

During tool operation, rotational motion of the tool is monitored at 86 based on the signal from the rotational rate sensor. When the rotational rate of the tool exceeds some empirically derived threshold (as shown at 87), this may indicate the onset of kickback condition; otherwise, processing control returns to the beginning of the algorithm. In addition to rotational rate of the tool about its spindle axis, it is envisioned that the rotational displacement, rotational acceleration, or some combination thereof as derived from the sensor signal may be used to determine the onset of a kickback condition.

Prior to initiating some protective operation, the microcontroller also evaluates the current draw of the motor at 88. Specifically, the rate of change of the motor current is measured. When the rate of change is positive and exceeds some predetermined threshold, then one or more protective operations are initiated at 90. If either the rate of change is not positive or the rate of change does not exceeds the threshold, then processing control returns to the beginning of the algorithm. In this case, a sudden change in the current draw is used to confirm the onset of the kickback condition. While the above description was provided with reference to a rotational rate sensor and a current sensor, it is readily understood that the broader aspects of the present invention encompass making such a determination may be based on input from other types of sensors.

Determination of a rotational condition may also be based on other types of criteria. For example, a rotational condition may be assessed based on the rotational energy experienced by the power tool. In this example, rotational energy is defined as EωTOOL=(I)(ωTOOL)2, where I is the moment of inertia and ωTOOL is the angular velocity. For this computation, the rate of angular displacement could be measured by a rotational rate sensor; whereas, the moment of inertia of the tool (ITOOL) could be preprogrammed into the controller based on the mass properties of the power tool (e.g., mass, rotation inertia and a center of gravity position) and a distance measure between the center of gravity position and the spindle axis. Initiating a protective operation based on EωTOOL is desirable because the energy condition is not tool specific and therefore could be applied to a variety of anti-kickback applications. Other criteria for determining a kickback condition are also within the broader aspects of the present invention.

FIG. 6 depicts another exemplary control system 100. The control system is comprised generally of a rotational rate sensor 32″, sensor processing logic 110, a motor controller 36″, a motor 14″ and a power supply 29″. The rotational sensor 32″ may be a single sensor, such as a gyroscope or accelerometer, or two or more sensors disposed within the tool. Sensor processing logic 110 may be implemented in software or hardware. Likewise, power-up and calibration functions may be performed with hardware, software or combination thereof.

During normal tool operation, sensor output is processed as follows. In this exemplary embodiment, the sensor output is rotational velocity. The sensor output passes through a low pass filter 111 before going into a null point and gain calibration routine 112. The purpose of the calibration routine is to remove any offset and compensate for any gains of the rate sensor before determining rotational conditions. Through either software or hardware means, the rate signal is then integrated at 113 to get position and derived at 114 to get acceleration. All three of the signals are then input to a comparator 115 which checks whether or not the value has exceeded a defined threshold. A logic block 116 (e.g., AND, OR, etc.) is configured so that any or all of the thresholds must be met before indicating a trip signal which is sent to the motor controller 36″. Although the tests are shown as comparators on position, rate, or acceleration, it is noted that the tests are not limited to thresholds alone. Combinations of each variable can be used such as if the rate is less than W then position must be greater than X for a trip event to occur. In another example, if rate is greater than Y then position must be greater than Z for a trip to occur.

In lieu of comparison functions, the control system may employ a look-up table as shown in FIG. 7. In this example, rotational position is charted against rotational velocity. Look-up tables having other parameters and further dimensions are also contemplated. Additionally, the values in the table may indicate the type of protective operation or point to another table for more processing.

FIG. 8 illustrates an exemplary calibration system 120 for a power tool 10 configured with the control system described above. The calibration system 120 is generally comprised of a test fixture 122, a test module 124, and a personal computer 126. To calibrate a power tool, the test module is first removed from the power tool and affixed to the test fixture 122. The rotational rate sensor along with the software routines which implement the control schemes described above are contained within the test module 124. The test fixture 122 is generally operable to rotate the test module 124 in a manner that may be experienced when module resides in the power tool. The personal computer 126 is configured to control operation of the test fixture 122 in accordance with a calibration routine as well as to interface with the test module 124 during the calibration process. It is also envisioned that in other configurations the entire power tool may affixed to and rotated by the test fixture.

An exemplary calibration procedure for a power tool is further described in relation to FIG. 9. First, a calibration routine is downloaded at 130 from the PC into the test module 124. The calibration routine cooperatively operates with the software routines of the control system to determine calibration values for the control system. The calibration procedure begins with the test module 124 measuring the output of the rotational rate sensor at 131 while the power tool remains stationary. This measured output serves as an offset or null calibration value (i.e., output value of the sensor when angular velocity is zero) for the rotational rate sensor. Next, the personal computer commands the test fixture 132 to rotate the test module 124 (e.g., clockwise) at predefined angular velocity for a predefined period of time. For example, the test fixture 122 may rotate the test module 124 at 50 degrees per second until 50 degrees of rotation is reached. During this movement, the test module is capturing the angular velocity as reported by the rotational rate sensor. The test module will compare the angular velocity 133 as reported by the rotational rate sensor with the known angular velocity at which the test module was rotated by the test fixture to determine a gain value. The gain value is temporarily stored by the test module for subsequent processing.

The personal computer then commands the test fixture 134 to rotate the test module in an opposite direction (e.g., counter-clockwise) at a predefined angular velocity for a predefined period of time. The test module again captures the angular velocity as reported by the rotational rate sensor and compares these captured values 135 with the known angular velocity to determine another gain value. The second gain value is also stored by the test module. Thus, there is a gain value for each direction of tool rotation.

To confirm the calibration values, the personal computer re-executes the calibration procedure at 136. In other words, the test fixture is commanded to rotate the test module at the predefined angular velocity in one direction and then in the opposite direction. The test module again captures the angular velocity as reported by the rotational rate sensor. At this point, the test module adjusts the measured angular velocity using the applicable calibration values and compares the adjusted values to the known angular velocity at which the test module was rotated by the test fixture. If the adjusted values fall within some defined tolerance of the expected values, these calibration values are sent by the test module to the personal computer. These calibration values can then be downloaded into memory of a power tool. During operation, the control system of the power tool will use the calibration values to adjust the output reported by the rotational rate sensor. It is readily understood that this type of calibration procedure may be undertaken for each power tool or once for each family of power tools.

The above description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.

Vanko, John Charles, Leh, Jason, Beers, David

Patent Priority Assignee Title
10357871, Apr 28 2015 Milwaukee Electric Tool Corporation Precision torque screwdriver
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11077509, Mar 16 2018 Milwaukee Electric Tool Corporation Pipe threader
11400570, Apr 28 2015 Milwaukee Electric Tool Corporation Precision torque screwdriver
11529725, Oct 20 2017 Milwaukee Electric Tool Corporation Power tool including electromagnetic clutch
11607790, Oct 26 2017 Milwaukee Electric Tool Corporation Kickback control methods for power tools
11648655, Oct 26 2017 Milwaukee Electric Tool Corporation Kickback control methods for power tools
11705721, Mar 10 2020 Milwaukee Electric Tool Corporation Kickback control methods for a power tool including a force sensor
11845173, Oct 16 2020 Milwaukee Electric Tool Corporation Anti bind-up control for power tools
Patent Priority Assignee Title
1990035,
2617971,
2776653,
3083508,
3463990,
3554302,
3616864,
3773117,
3847229,
3939920, Sep 19 1974 Standard Pressed Steel Co. Tightening method and system
3963364, Dec 24 1954 Tool control system and method
4060115, Jan 23 1976 Handle for hand tools to be rotated during operation
4066133, Sep 04 1974 Robert Bosch G.m.b.H. Power hand tool
4095547, May 01 1975 Brown Brothers & Company, Ltd. Acceleration measuring device
4104778, Jan 27 1977 Ingersoll-Rand Company Method and apparatus for fastener tensioning
4143467, May 01 1978 Honeywell INC Semi-automatic self-contained magnetic azimuth detector calibration apparatus and method
4249117, May 01 1979 Black and Decker, Inc. Anti-kickback power tool control
4262528, Dec 24 1977 C. Plath KG Apparatus for measuring the torque applied to a wrench
4267914, Apr 26 1979 Black & Decker Inc. Anti-kickback power tool control
4305471, Aug 09 1976 Rockwell International Corporation Simplified fastening technique using the logarithmic rate method
4418765, Jan 16 1981 Matsushita Electric Industrial Company, Limited Power-driven screwdriver with a torque control
4426588, Jul 17 1981 Hilti Aktiengesellschaft Weighting circuit for an electrical torque signal in a drilling machine
4448261, Oct 31 1980 Hilti Aktiengesellschaft Motorized hand tool for drilling
4487270, Nov 24 1981 Black & Decker Inc. Electric tool, particularly a handtool, with torque control
4510802, Sep 02 1983 L-3 Communications Corporation Angular rate sensor utilizing two vibrating accelerometers secured to a parallelogram linkage
4573556, May 20 1983 Aktiebolaget Electrolux Actuator for the release of an automatic emergency brake of a hand-operated powered tool
4576270, Feb 28 1983 The Aro Corporation Torque control and fluid shutoff mechanism for a fluid operated tool
4587468, Jan 25 1984 Kabushiki Kaisha Morita Seisakusho Sudden stop circuit for a brushless micromotor
4601206, Sep 16 1983 Ferranti International PLC Accelerometer system
4628233, Mar 23 1984 Black & Decker Inc. Microprocessor based motor control
4638870, Dec 21 1983 Hilti Aktiengesellschaft Motor driven hand-held device containing a displacement mass
4648282, May 15 1984 Cooper Technologies Company Power screwdriver
4732221, Jan 21 1987 Stewart-Warner Corporation Pneumatic chipping hammer and method of manufacture
4744248, Dec 05 1983 Litton Systems, Inc. Vibrating accelerometer-multisensor
4754669, Oct 24 1985 Black & Decker Inc. Motor driven screwdriver with spindle lock
4759225, Jun 01 1987 Ryeson Corporation Torque tool and torque tool analyzer
4793226, Mar 04 1986 Manual device for driving screws
4820962, Oct 31 1986 HILTI AKTIENGESELLSCHAFT, FL-9494 SCHAAN, FURSTENTUM LIECHTENSTEIN Arrangement for automatic working data set-up for driving implements
4841773, May 01 1987 Litton Systems, Inc. Miniature inertial measurement unit
4846027, Aug 19 1988 Taiwan Silver Star Industrial Co., Ltd. Screwdriver
4871033, Jan 30 1988 Hilti Aktiengesellschaft Motor-driven hand tool with braking torque device
4878404, Sep 14 1988 Electric screwdriver
4885511, Apr 11 1986 Hilti Aktiengesellschaft Drive control with overload protection for a drill device
4948164, Jan 29 1988 NISSAN MOTOR COMPANY, LIMITED, 2, TAKARA-CHO, KANAGAWA-KU, YOKOHAMA-SHI, KANAGAWA-KEN, JAPAN Actively controlled suspension system with compensation of delay in phase in control system
4961035, Feb 04 1988 Hitachi, Ltd. Rotational angle control of screw tightening
4996877, Sep 30 1988 Litton Systems, Inc. Three axis inertial measurement unit with counterbalanced mechanical oscillator
5014793, Apr 10 1989 Measurement Specialties, Inc. Variable speed DC motor controller apparatus particularly adapted for control of portable-power tools
5036925, Sep 01 1988 Black & Decker Inc Rotary hammer with variable hammering stroke
5149998, Aug 23 1991 DYNAMATIC CORPORATION Eddy current drive dynamic braking system for heat reduction
5155421, Jun 12 1989 Atlas Copco Tools AB Power wrench for tightening screw joints
5156221, Jun 22 1990 CEKA ELEKTROWERKZEUGE AG & CO KG, A CORP SWITZERLAND Method of and arrangement for controlling the operation of a hand-held electrical device
5166882, Mar 31 1989 The United States of America as represented by the Secretary of the Navy System for calibrating a gyro navigator
5174045, May 17 1991 SEMITOOL, INC Semiconductor processor with extendible receiver for handling multiple discrete wafers without wafer carriers
5200661, Dec 15 1989 HIRE, CHARLES J Slotless, brushless, large air gap electric motor
5201373, Jan 05 1991 Robert Bosch GmbH Hand held power tool with safety coupling
5212862, Oct 09 1990 Allen-Bradley Company, Inc. Torque-angle window control for threaded fasteners
5232328, Mar 05 1991 SEMITOOL, INC A CORP OF MONTANA Robot loadable centrifugal semiconductor processor with extendible rotor
5241861, Feb 08 1991 L-3 Communications Corporation Micromachined rate and acceleration sensor
5245747, Sep 22 1989 Atlas Copco Tools AB Device for tightening threaded joints
5247466, Mar 29 1990 Hitachi, Ltd.; Hitachi Automotive Engineering Co., Ltd. Angular rate detection apparatus, acceleration detection apparatus and movement control apparatus, of moving body
5284217, Oct 09 1990 Allen-Bradley Company, Inc. Apparatus for tightening threaded fasteners based upon a predetermined torque-angle specification window
5311069, Sep 06 1991 Silicon Systems, Inc. Driver circuitry for commutated inductive loads
5345382, May 15 1992 TomTom International BV Calibration method for a relative heading sensor
5357179, Jun 19 1992 Pace, Incorporated; Pace Incorporated Handheld low voltage machining tool
5361022, Mar 23 1993 E. F. Bavis & Associates, Inc. Method and apparatus for electrical dynamic braking
5365155, Oct 22 1990 Marquardt GmbH Rotational speed control and use of same to control the rotational speed of an electric hand tool motor
5383363, Feb 10 1993 THE BANK OF NEW YORK MELLON, AS ADMINISTRATIVE AGENT Inertial measurement unit providing linear and angular outputs using only fixed linear accelerometer sensors
5401124, Apr 12 1991 Robert Bosch GmbH Hand-held power tool with jamming-detection sensor
5418422, May 06 1992 U S PHILIPS CORPORATION Combination of display tube and deflection unit comprising line deflection coils of the semi-saddle type with a gun-sided extension
5425165, Dec 15 1989 HIRE, CHARLES J Method of making a slotless, brushless, large air-gap electric motor
5440218, Jul 13 1994 General Electric Company Reversible switched reluctance motor operating without a shaft position sensor
5476014, Dec 21 1992 DaimlerChrysler AG Process and a device for the rotation-angle-monitored tightening or loosening of screw connections
5484026, Sep 03 1993 Nikon Corporation Handheld electromotive tool with sensor
5493909, Jan 30 1991 Mitsubishi Denki Kabushiki Kaisha Method of and an apparatus for detecting control information
5535306, Jan 28 1993 Applied Materials Inc. Self-calibration system for robot mechanisms
5538089, Jun 05 1995 The Black & Decker Corporation Power tool clutch assembly
5557990, Jul 27 1995 AEROMAX-TOOL SPECIALTIES LIMITED Actuating device for use in powered screwdriver
5563482, Sep 30 1993 Black & Decker Inc Power tools
5584619, Dec 28 1993 Hilti Aktiengesellschaft Method of and arrangement for preventing accidents during operation of a manually-operated machine tool with a rotatable toolbit
5589644, Dec 01 1994 SNAP-ON TOOLS WORLDWIDE, INC ; SNAP-ON TECHNOLOGIES, INC Torque-angle wrench
5615130, Dec 14 1994 Maxim Integrated Products, Inc Systems and methods to gather, store and transfer information from electro/mechanical tools and instruments
5619085, Dec 15 1989 DYNAMIC ENERGY SYSTEMS, L L C Slotless, brushless, large air-gap electric motor
5635638, Jun 06 1995 Analog Devices, Inc Coupling for multiple masses in a micromachined device
5637968, Oct 25 1993 STANLEY WORKS, THE Power tool with automatic downshift feature
5701961, Jul 05 1996 Ingersoll-Rand Company Electronic push to start nutrunner
5704435, Aug 17 1995 Milwaukee Electric Tool Corporation Hand held power tool including inertia switch
5714698, Feb 03 1994 Canon Kabushiki Kaisha Gesture input method and apparatus
5730232, Apr 10 1996 Two-speed fastener driver
5738177, Jul 25 1996 Black & Decker Inc Production assembly tool
5754019, Mar 24 1995 Marquardt GmbH Method and circuit arrangement for operating an electric motor
5793168, Aug 23 1996 Fairchild Semiconductor Corporation Active deceleration circuit for a brushless DC motor
5795988, Jul 01 1996 AlliedSignal Inc Gyroscope noise reduction and drift compensation
5806401, Jan 04 1994 THOMAS E RAJALA; BEVERLEE J ERVEN; JANET R NELSON Satellite sawmill with adjustable saws and automatic sawbolt centering device
5812420, Sep 05 1995 Nikon Corporation Vibration-preventive apparatus and exposure apparatus
5831402, Mar 15 1996 Double direction actuating type tool of loose forward and loose backward assisting style
5879111, Nov 11 1996 Hilti Aktiengesellschaft Hand-held device
5914882, Oct 09 1996 Hilti Aktiengesellschaft Device for and method of preventing accidents in hand-operated machine tools due to tool jamming
5954457, Nov 11 1996 Hilti Aktiengesellschaft Hand-held device
5971091, Feb 24 1993 DEKA Products Limited Partnership Transportation vehicles and methods
5981557, May 18 1995 Zeria Pharmaceutical Co., Ltd. Aminothiazole derivative, medicament containing the same, and intermediate for preparation of said compound
5984020, Aug 17 1995 Milwaukee Electric Tool Corporation Power toll including inertia responsive element
5996707, Nov 02 1995 Robert Bosch GmbH Hand power tool
6005489, Aug 18 1994 Atlas Copco Tools AB Electric power tool with code receiver
6044918, Sep 20 1995 Hilti Aktiengesellschaft Percussion blow added manually operable drilling tool
6049460, Jul 19 1999 Eaton Corporation Trigger actuated control having supplemental heat sink
6055142, Apr 23 1997 Hilti Aktiengesellschaft Manually guided machine tool with a safety device
6058815, Dec 22 1995 SIMPSON STRONG-TIE COMPANY INC Hand held power tool
6062939, Aug 07 1998 Mattel, Inc Toy power tool
6111515, Dec 10 1998 Hilti Aktiengesellschaft Method of and apparatus for preventing accidents during working with hand-held tools with a rotatable working tool
6129699, Oct 31 1997 BAXTER HEALTHCARE SA; Baxter International Inc Portable persistaltic pump for peritoneal dialysis
6138629, Aug 31 1995 ISAD Electronic Systems GmbH & Co. KG; Grundl und Hoffman GmbH System for actively reducing radial vibrations in a rotating shaft, and method of operating the system to achieve this
6147626, Aug 11 1998 TOMTOM NAVIGATION B V Determination of zero-angular-velocity output level for angular velocity sensor
6158929, Jul 01 1998 BAE SYSTEMS, plc Electronically triggered surface sensor unit
6161629, Nov 19 1996 Power wrench
6209394, Oct 23 1997 STMICROELECTRONICS S R L Integrated angular speed sensor device and production method thereof
6236177, Jun 05 1998 Milwaukee Electric Tool Corporation Braking and control circuit for electric power tools
6387725, Oct 23 1997 STMicroelectronics S.r.l. Production method for integrated angular speed sensor device
6408252, Aug 01 1997 Dynalog, Inc.; DYNALOG, INC Calibration system and displacement measurement device
6415875, Jan 12 1999 Robert Bosch GmbH Hand-held power tool
6479958, Jan 06 1995 Black & Decker Inc. Anti-kickback and breakthrough torque control for power tool
6516896, Jul 30 2001 The Stanley Works; STANLEY WORKS, THE Torque-applying tool and control therefor
6567068, Aug 05 1996 Sony Corporation Information processing device and method
6581714, Feb 24 1993 DEKA Products Limited Partnership Steering control of a personal transporter
6612034, Jan 24 2000 Koninklijke Philips Electronics N V Hand-held electrical appliance for personal care or for use as a tool
6640733, Dec 08 1999 HUFFMEYER, EDWARD H Inclinometer-controlled apparatus for varying the rate of seed population
6779952, Sep 20 2001 Stepless speed change bench drill
6796921, May 30 2003 Eastway Fair Company Limited Three speed rotary power tool
6834730, Apr 29 1999 Power tools
6836614, Jul 06 1993 Black & Decker Inc. Electrical power tool having a motor control circuit for providing control over the torque output of the power tool
6842991, Jul 31 2002 Honeywell International Inc Gyro aided magnetic compass
6843140, Aug 19 2002 Hilti Aktiengesellschaft Safety module for a multifunctional handheld tool
6871128, Apr 19 2001 Kawasaki Jukogyo Kabushiki Kaisha Speed change control method and speed change controller
6910540, Apr 25 2001 Torque control system for electrically driven rotating tools
6923268, Feb 28 2001 Electric rotational tool driving switch system
6965835, Sep 28 2001 SPX Corporation Torque angle sensing system and method with angle indication
6968908, Feb 05 2003 Makita Corporation Power tools
6983506, Nov 20 2001 KAIZEN SYSTEMS, INC Universal, interchangeable tool attachment system
7011165, May 02 2000 Hilti Aktiengesellschaft Rotating electric hand tool implement with safety routine
7036703, Jan 27 2003 Hilti Aktiengesellschaft Hand-held working tool
7055620, Apr 06 2001 Robert Bosch GmbH Hand-held machine tool
7055622, Nov 20 2001 Black & Decker Inc. Power tool having a handle and a pivotal tool body
7090030, Sep 03 2002 JERGENS, INC Tranducerized torque wrench
7121358, Apr 29 1999 Power tools
7121598, Jun 05 2003 Societe de Prospection et D Inventions Techniques Spit Pole for remote operation of a hand tool
7134364, Sep 29 2003 Robert Bosch GmbH Battery-driven screwdriver
7154406, Aug 10 2000 Black & Decker Inc. Power tool level indicator
7182148, Aug 11 2004 Tool with motion and orientation indicators
7197961, Sep 29 2003 Robert Bosch Tool Corporation Battery-driven screwdriver with a two-part motor housing and a separate, flanged gear unit
7225884, Oct 26 2004 Robert Bosch GmbH Hand power tool, in particular drilling screwdriver
7234536, Aug 04 2004 C. & E. FEIN GMBH Power screwdriver
7331406, Jun 21 2004 KYOCERA SENCO INDUSTRIAL TOOLS, INC Apparatus for controlling a fastener driving tool, with user-adjustable torque limiting control
7347158, Jan 22 2004 DEEPFLIGHT ASSIGNMENT FOR THE BENEFIT OF CREDITORS , LLC Safety system for scuba divers operating underwater propulsion devices
7359816, May 25 2005 Analog Devices, Inc Sensor calibration method and apparatus
7372226, Jan 28 2004 Robert Bosch GmbH Method for switching off a power tool
7395871, Apr 24 2003 Black & Decker Inc. Method for detecting a bit jam condition using a freely rotatable inertial mass
7400106, Nov 04 2005 Credo Technology Corporation; Robert Bosch GmbH Method and apparatus for providing torque limit feedback in a power drill
7410006, Oct 20 2004 Black & Decker Inc Power tool anti-kickback system with rotational rate sensor
7456603, Jul 19 2005 HITACHI ASTEMO, LTD Phase detection circuit, resolver/digital converter using the circuit, and control system using the converter
7463952, Oct 13 2004 Continental Automotive Systems US, Inc Method and device for processing measurement signals from a movement sensor on board a motor vehicle
7469753, Jun 01 2005 Milwaukee Electric Tool Corporation Power tool, drive assembly, and method of operating the same
7487844, Nov 04 2005 Credo Technology Corporation; Robert Bosch GmbH Drill with solid state speed control
7487845, Apr 24 2003 Black & Decker Inc. Safety mechanism for a rotary hammer
7504791, Jan 22 2004 Robert Bosch GmbH Electric power tool with optimized operating range
7506694, Sep 13 2002 Black & Decker Inc Rotary tool
7526398, Sep 21 2005 Samsung Electronics Co., Ltd.; SAMSUNG ELECTRONICS CO , LTD Method and apparatus for calibrating gyro-sensor
7546785, Aug 09 2004 Robert Bosch GmbH Battery-operated screwdriver
7551411, Oct 12 2005 Black & Decker Inc Control and protection methodologies for a motor control module
7552781, Oct 19 2005 Black & Decker Inc Power tool anti-kickback system with rotational rate sensor
7565844, Nov 28 2005 Snap-On Incorporated Torque-angle instrument
7642741, Apr 27 2005 Handheld platform stabilization system employing distributed rotation sensors
7650699, Jul 22 2005 Electric drill
7681659, Oct 20 2004 Black & Decker Inc. Power tool anti-kickback system with rotational rate sensor
7682035, Sep 01 2005 Robert Bosch GmbH Housing device for hand-held power tool
7688028, Oct 18 2004 Black & Decker Inc Cordless power system
7689378, Feb 15 2005 C LAN WIRELESS INC Motion sensing apparatus, systems and techniques
7708085, Nov 04 2005 Credo Technology Corporation; Robert Bosch GmbH Articulating drill with optical speed control and method of operation
7723953, May 04 2009 Robert Bosch GmbH Battery-operated screwdriver and charger shell therefor
7730963, Apr 24 2003 Black & Decker Inc. Safety mechanism for a rotary hammer
7774155, Mar 10 2006 NINTENDO CO , LTD Accelerometer-based controller
7832286, Apr 07 2005 Kyoto Tool Co., Ltd.; Hosiden Corporation Torque wrench
7861796, Nov 04 2005 Robert Bosch GmbH Method of operating drill with solid state speed control
7882899, Aug 29 2007 POSITEC POWER TOOLS SUZHOU CO , LTD Power tool having control system for changing rotational speed of output shaft
7882900, Aug 29 2007 POSITEC POWER TOOLS SUZHOU CO , LTD Power tool with signal generator
7900715, Jun 15 2007 POSITEC POWER TOOLS SUZHOU CO , LTD Variable speed tool and variable speed control method
7912664, Sep 11 2008 Northrop Grumman Guidance and Electronics Company, Inc. Self calibrating gyroscope system
7926585, Nov 04 2005 Credo Technology Corporation; Robert Bosch GmbH Method and apparatus for an articulating drill
7936148, Aug 09 2004 Robert Bosch GmbH Battery-operated screwdriver and charger shell therefor
7942084, Dec 06 2006 SIEMENS INDUSTRY, INC Powered driver and methods for reliable repeated securement of threaded connectors to a correct tightness
8025106, Apr 12 2006 Robert Bosch GmbH Method for tightening a screw connection and screw driving tool
8136382, May 07 2010 Northrop Grumman Guidance and Electronics Company, Inc. Self-calibration of scale factor for dual resonator class II Coriolis vibratory gyros
8179069, Aug 24 2007 Makita Corporation Electric power tool, control unit and recording medium
20010042630,
20020033267,
20020053892,
20020066632,
20020170754,
20030000651,
20030037423,
20030042859,
20030116332,
20030196824,
20040011632,
20040069511,
20040104034,
20040182175,
20040211573,
20040226424,
20040226728,
20050000998,
20050217874,
20060081368,
20060081386,
20060103733,
20060124331,
20060243469,
20070068480,
20070084613,
20070095634,
20070144270,
20070256914,
20070281274,
20080011102,
20080110653,
20080276760,
20090051306,
20090065225,
20090078057,
20090120657,
20090139738,
20090211774,
20090295313,
20100188245,
20100189887,
20100245086,
20100247754,
20100256939,
20100263591,
20100263891,
20110079406,
20110153081,
20110160903,
20110202175,
20110301900,
20120000682,
20120090863,
D279254, May 31 1983 Alterra Holdings Corporation Hand grip for hand tools
D326043, May 19 1989 Hitachi Koki Company, Limited Electric screw driver
D339279, Jan 08 1992 WILLI HAHN GMBH & CO KG Handle for a screwdriver
D378727, Jul 25 1995 One World Technologies Limited Rotary tool
D387964, Oct 02 1995 MECCANO S N Screwdriver
D392532, Nov 27 1996 Driving assembly of a screwdriver
D392535, May 15 1997 Team Fair Holdings Limited Tool handle
D485737, Jan 10 2003 Toolovation, LLC Battery powered screwdriver
D493888, Feb 04 2003 Covidien AG; TYCO HEALTHCARE GROUP AG Electrosurgical pencil with pistol grip
D494829, May 19 2003 Handle for screwdriver
D513160, Sep 17 2004 HBC FQ LLC Cordless drill
D517634, Sep 22 2004 TAYLOR MADE GOLF COMPANY, INC Golf club wrench
D534651, Apr 01 2004 Kinamed, Inc. Powered surgical screwdriver
D565380, Jul 19 2006 Screwdriver T-handle
D606827, Jun 18 2009 3M Innovative Properties Company Small, portable power tool
D613144, Oct 08 2008 Hand tool
D618527, Mar 22 2010 IBT Holdings LLC T tool handle
DE10117121,
DE102006016441,
DE102007048052,
DE102007062727,
DE102009001298,
DE102009007977,
DE10309414,
DE10318798,
DE10340710,
DE10348756,
DE19540718,
DE19620124,
DE19632363,
DE19651124,
DE19726006,
DE19900882,
DE2442260,
DE3239847,
DE3400124,
DE3938787,
DE4204420,
DE4243317,
DE4334933,
EP18603,
EP199883,
EP303651,
EP345655,
EP666148,
EP771619,
EP773854,
EP841126,
EP841127,
EP1008422,
EP1151828,
EP1188521,
EP1201373,
EP1379362,
EP1391271,
EP1398119,
EP1447177,
EP1452278,
EP1470898,
EP1524084,
EP1670134,
EP1711308,
EP1878541,
EP1900484,
GB1261479,
GB2086277,
GB2306356,
GB2347100,
GB2400811,
GB2420843,
GB2436959,
JP10156739,
JP2005144625,
JP4065677,
JP4226869,
JP60252213,
JP7270444,
JP8128825,
JP8197445,
JP9038815,
RE33379, Mar 23 1984 Black & Decker Inc. Microprocessor based motor control
RU2103156,
WO2004024398,
WO2005095061,
WO2006045072,
WO2009032314,
WO2009083306,
WO2009136840,
WO8806508,
/
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