An electrical speed control system for selectively connecting an accessory to a vehicle engine having a conventional alternator driven thereby, utilizes the voltage output of the alternator stator to determine the rotational speed of the engine, and permits the accessory to be connected to the engine when the shaft speed is at or below a maximum safe engagement speed, and disconnects the accessory when the speed is above a maximum safe speed for the accessory. The speed control system further prevents reengagement of the accessory after reaching and falling below the high-speed disengage point until the rotational speed of the engine has fallen below the maximum safe engagement speed level.
|
12. In combination with a system for driving an accessory from an engine wherein the accessory cannot be safely connected to the engine above a first engine speed and once connected, cannot be safely operated above a second engine speed, a speed control system having a first means for selectively connecting and disconnecting an accessory to and from the engine, the engine having a rotating shaft and a signal generating device for producing a speed signal indicative of the speed of rotation of the rotating shaft; said speed control system comprising:
second means establishing a first signal level indicative of said first engine speed, third means establishing a second signal level indicative of said second engine speed, said first means permitting connection of an accessory to the rotating shaft only when said speed signal is less than said first signal level and causing an accessory to be disconnected from said rotating shaft when said speed signal exceeds said second signal level, said first means permitting reconnection of an accessory to the rotating shaft after an accessory has been disconnected from the rotating shaft only when said speed signal is again less than said first signal level.
1. An electrical speed control system for selectively connecting an accessory to an engine having a rotating electric signal producing device and a rotating shaft, said speed control system comprising:
means connected to receive a signal from said signal producing device for producing a speed signal indicative of the rotational speed of said shaft; signal level sensing means connected to receive said speed signal for determining if said speed signal is indicative of a speed below a preselected first level and if said speed signal is indicative of a speed above a preselected second level, and for producing an energization signal whenever said speed signal is below said first preselected threshold level, for interrupting said energizing signal when said speed signal is above said second level for maintaining said interruption of said energization signal until said speed signal falls below said first preselected level and for reestablishing said energizing signal when said speed signal again falls below said first preselected level; and switch means connected to said accessory means, and a source of electrical power, said energization signal actuating said switch whenever said energization signal is present.
13. In combination with a system for driving an accessory from an engine wherein the accessory cannot be safely connected to the engine above a first engine speed and once connected, cannot be safely operated above a second engine speed, a speed control system having a means for selectively connecting the accessory to the engine, the engine having a rotating shaft and a signal generating device for producing a speed signal indicative of the speed of rotation of the rotating shaft; said speed control system comprising:
first means connected to receive said speed signal from said signal generating device, second means establishing a first signal level indicative of said first engine speed, third means establishing a second signal level indicative of said second engine speed, fourth means permitting connection of an accessory to the rotating shaft only when said speed signal is less than said first signal level, and fifth means causing an accessory to be disconnected from said rotating shaft when said speed signal exceeds said second signal level, said fourth means permitting reconnection of an accessory to the rotating shaft after an accessory has been disconnected by said fifth means only when said speed signal signal is again less than said first signal level.
11. An electronic speed control system for use in selectively controlling the driving of an accessory by a rotating shaft, said system comprising:
means connected to said rotating shaft for producing a speed signal which is a function of the rotational speed of said rotating shaft; first level detecting means connected to receive said speed signal for producing an output signal indicating that the speed is below a first preselected threshold level; second level detecting means connected to receive said speed signal for producing an output signal indicating that the speed is above below a second predetermined threshold level; latch means connected to receive said first and second level detecting means output signals and for producing an output signal only if said speed is: (1) remains below said first preselected threshold level, (2) has exceeded said first preselected threshold level and is but remains below said second preselected threshold level and, or (3) having exceeded said second level, thereafter falls below said first preselected threshold level; and switch means connected to receive said output signal of said latch means and connected to said accessory and an electric power source for actuating said accessory only upon the occurrence of said output signal from said latch means.
6. An electronic speed control system for use in selectively controlling the driving of an accessory by the rotating shaft of an engine of the type employing an alternator; said system comprising:
converter means electrically connected to said alternator for producing a rotational speed signal which is a function of the rotational speed of said rotating shaft; first level detecting means connected to receive said rotational speed signal for producing an output signal indicating that the speed is below a first preselected threshold level; second level detecting means connected to receive said rotational speed signal for producing an output signal indicating that the speed is below a second predetermined threshold level; latch means connected to receive said first and second level detecting means output signals and for producing an output signal only if said speed is: (1) remains below said first preselected threshold level, (2) has exceeded said first preselected threshold level and is but remains below said second preselected threshold level and, or (3) having exceeded said control level, thereafter falls below said first preselected threshold level; and switch means connected to receive said output signal of said latch means and connected to said accessory and an electric power source for actuating said accessory only upon the occurrence of said output signal from said latch means.
2. The system of
3. The system of
4. The system of
5. The system of
first comparator means connected to receive said speed signal for producing an output signal indicating when said speed signal is below said first preselected level; second comparator means connected to receive said speed signal for producing an output signal indicating when said speed signal is below said second preselected level; and latch means connected to receive said first and second comparator output signals for producing said energization signal when said first comparator means output signal is present, for interrupting said energization signal when said second comparator means output signal is absent, and for maintaining said interruption until both first and second comparator means output signals are present simultaneously.
7. The system of
8. The system of
9. The system of
10. The system of
14. The system of
said accessory being characterized in that it is unsafe to connect it to said rotating shaft when said speed signal is above said preselected first level, said engine running continuously while the speed signal falls from above said second level to below said first level. 15. In the combination of claim 13: said engine being capable of running while the accessory is disconnected from said shaft.
|
|||||||||||||||||
FIG. 2 is a detailed circuit diagram of the inventive system of FIG. 1; and The adjustment means in each of blocks 22 and 24 may be a potentiometer with a wiper arm.
The operating curve of the latch is illustrated in block 28; wherein the input and output signals are the abscissa and ordinate. respectively. When signals are produced by comparators 18 and 20, the input signal achieves level C and the output current rises along Curve A. Loss of the signal from comparator 18 only causes the input signal to drop to between levels B and C and the output current stays high. Loss of signal from both comparators causes the input signal to fall below level B and the current output falls along line D to its original level.
The latch circuit, when activated, provides an energization signal on line 30 which, in this embodiment, is fed to a relay 32 and serves to energize its relay coil 34. The relay 32 is connected to a current source 36 and, in a situation where the inventive device is used on an internal combustion engine, the voltage source 36 may be the battery of the engine. The relay 32 has associated with it a normally open terminal 38 and a normally closed terminal 40. The battery or voltage source 36 is connected to the actuator arm 42 of the relay. Accordingly, it may be seen that as the relay coil 34 is energized, the normally open terminal 38 is connected to the voltage source 36 through the actuator arm 42. It is contemplated that the accessory or accessory-engine interface will be connected to the normally open terminal 38 for actuation in response to the application of voltage thereto.
Referring now to the circuit diagram of the system illustrated in FIG. 2, the frequency variable signal from the engine-associated alternator 10 is supplied on line 12 and is passed through a rectifier network consisting of capacitor 50 and resistors 51 and 53, diode or rectifier 52 and resistor 54 to an input circuit of a first operational amplifier 56. The operational amplifier 56 is provided with a feedback circuit consisting of resistors 61 and 63 so that it operates as an integrator and integrates the rectified input signal to produce an output signal having a DC level that is a function of the frequency of the input signal appearing on lead 12.
The operational amplifier 56 has its minus input terminal connected through a voltage divider nework comprising resistors 100 106, 84 and 102 to the low side of battery 36.
The output signal on line 62 from the operational amplifier 56 is fed through a diode 64 and resistor 66 via lead 16 to the input resistor 68 and input resistor 70 of second and third operational amplifiers 72 and 74, respectively.
Operational amplifier 74 corresponds to the lower level comparator, 18 of FIG. 1, and is connected as an integrator by means of capacitor 76. The low level adjustment means of comparator 74 is provided by a potentiometer comprising the resistor 84 having a wiper 75 connected via lead 82 and resistor 80 to the negative terminal of the comparator. Access to this potentiometer is externally available to the operator of the equipment.
The output of the operational amplifier 74 is fed on line 86 through a resistor 88 via line 90 to the negative output terminal of a fourth operational amplifier 92.
The DC speed signal, on lead 16 is also fed to a third integrator amplifier 72 and is compared with a voltage on its negative terminal. This reference voltage is derived through a first resistor 94, connected via line 96 to wiper 97 of a second potentiometer 98. Potentiometer 98 is connected in parallel with the first potentiometer 84 and is placed across a voltage by way of line 100 through resistor 102 to the one side of the battery 36 and to the return side by way of line 104, resistor 106, line 108, parallel diode 110 and resistor 109, lead 111, resistor 122 and diode 124. The ground connection is via diode 112 to point 114.
Potentiometer 98 corresponds to the upper level adjusting means 24 of FIG. 1 and is also made externally available to the operator of the inventive unit, so that no disassembly is required in order to adjust the upper threshold level.
The operational amplifier 92 corresponds to the latching circuit 28 of FIG. 1 and has its positive input connected via lead 116 and resistor 118 to lead 111. The amplifier is operated in the current mode with feedback to the bias input provided via resistor 117. If current appears on both of leads 86 and 128, indicating that the signal on lead 16 is below both thresholds, the comparator 92 is rendered conductive. Current flow through the feedback, i.e., resistor 117, reduces the bias on lead 116 so that the signal on lead 128 is sufficient to sustain conduction of the comparator.
Conduction of the comparator 92, energizes the relay 34 closing contact 42 to contact 38 which is connected to the engine-accessory interface.
The four operational amplifiers comprising this preferred embodiment can be discrete components, or they can be formed on a single I C chip, which is commercially available, for example, National Semiconductor device LM 3900.
With reference to the above-described circuit diagram, the The operation of the present invention is now described with reference to the graphs of FIG. 3. FIG. 3 represents a plot of the voltage at four separate points in the circuit diagram of FIG. 2 and the system diagram of FIG. 1, plotted against continuous time on the abscissa.
Curve A represents the output voltage from the frequency to voltage converter, as represented by the voltage on line 16, and it may be seen that as the driving engine is speeded up and slowed down, the level of the signal varies accordingly. An upper threshold level, the overspeed level, is represented by the dashed line at 142, and the lower threshold level, the engage point, is represented by the dashed line at 144.
Wave form C represents the output signal on line 86 from the engage operational amplifier 74. It may be seen that when the input signal at terminal 71 of operational amplifier 74 is less than the reference voltage appearing on line 78, obtained by adjusting the wiper arm of potentiometer 84, operational amplifier 74 lower level comparator. Lower level comparator 18 produces an output signal and continues to maintain this output signal until the speed curve A crosses the engage level 144, whereupon operational amplifier 74 lower level comparator 18 ceases to produce an output signal. Operational amplifier 74 Lower level comparator 18 remains in this mode until the speed signal A falls below the engage level 144, whereupon at time T4 the engage operational amplifier 74 lower level comparator 18 again produces an output signal until the curve A again crosses the engage level 144 at time T5, when the output ceases. Upon reaching time T8, the curve A drops below the engage level 144 and operational amplifier 74 lower level comparator 18 again produces an output signal.
Wave form D represents the output of the disengage operational amplifier 72 as represented at 128 in FIG. 2. An output is produced by operational amplifier 72 when the reference voltage at line 95 obtained from potentiometer 98 is greater than the voltage on the input at 69. upper level comparator 20. Accordingly, operational amplifier 72 upper level comparator 20 produces a signal at time T0 and continues thus until the speed curve A crosses the overspeed threshold level 142 at time T2, whereupon the operational amplifier 72 upper level comparator 20 output at 128 ceases until the speed curve A drops below the overspeed threshold 142, which occurs at time T3. The disengage operational amplifier has then sensed that the engine speed has dropped below the upper threshold level and, accordingly, an output signal is produced until the engine speed again rises above that threshold level, which occurs at time T6. Similarly, at time T7 when the speed drops below the overspeed 142, the disengage operational amplifier again produces an output signal.
Wave form B represents the output signal or energization signal from the latch circuit, appearing on line 30 of FIGS. FIG. 1 and 2. The rise time of this latch output signal is delayed for approximately two seconds due to the action of capacitor 126 in FIG. 2. This is shown by the relatively slow rise time of wave form B compared with the other wave forms. The two-second delay is to prevent chatter in the interface. As indicated in FIG. 2, the reference voltage of the latch operational amplifier 92 is selected so that operational amplifier 92 changes states only if the output from the engage operational amplifier 74 and the disengage operational amplifier 72 are present at line 90. Accordingly, it It is seen that at time T0 both wave forms C and D are high and accordingly, the output wave form B of the latch circuit is also high and remains high until both signals on line 90 are removed voltage 140 exceeds overspeed threshold 142. This latter occurs at time T2 at which time the latch is turned off and the energization signal discontinued. The latch remains off or interrupted until both operational amplifiers, 72 and 74, are again producing an output signal on line 90 voltage 140 dips below engage threshold 144. This condition occurs at time T4.
It is apparent that once the speed has reached the overspeed threshold level, 142, the energization signal to the relay is not produced until the driving engine speed falls below the engage level 144. The energization signal remains on until both of the comparators lose their output voltage, which occurs at point T6, where the speed curve A exceeds the overspeed threshold 142. At this point, exemplary curve A shows a severe and sudden drop in engine speed and at time T8 both of the operational amplifiers 72 and 74 produce an output the voltage on line 26 rises along curve A to operate latch 28.
The circuit of FIG. 2 employs, for example, circuit values as set forth below:
| ______________________________________ |
| Battery 36: |
| 12 VDC Supply from vehicle Electrical System |
| Capacitors: |
| 50 & 60 = .0022 mfd. 16 v |
| 101,125,126 = 8.2 mfd. Electrolytic (TIM 825) 15 v |
| 76-.022 mfd. 100 v |
| Diodes: |
| 52 = 100 v 20 ma |
| 127 = 20 v 200 ma |
| 153 = 100 v 20 ma |
| 115 = 20 v 200 ma |
| 64 = 20 v 200 ma |
| 112 = 20 v 200 ma |
| 132 = 100 v 20 ma |
| 110 = 100 v 20 ma |
| 124 = 20 v 200 ma |
| 129 = 400 v 30 a (IN4004) |
| Relay: |
| 34 = 65FP1A Sigma |
| Resistors: |
| 51 = 470 119 = 3.3 M 118 = 1.8 M |
| 53 = 10K 66 = 1K 117 = 680K |
| 54 = 2.2 M |
| 130 = 100K 109 = 220K |
| 63 = 100K 131 = 18 M 88 = 1 M |
| 61 = 820K 94 = 689K 70 = 1 M |
| 65 = 1 M 68 = 1 M 80 = 820K |
| 106 = 4.7K 103 = 10K 84 = 10K (Adjustable) |
| 100 = 2.2 M |
| 102 = 8.2K 98 = 10K (Adjustable) |
| 107 = 100K 122 = 1K |
| ______________________________________ |
The foregoing description is presented by way of example only and is not intended to limit the scope of the present invention, except as set forth in the appended claims. For example, the relay could be replaced by a solid-state switch, such as a silicon controlled rectifier, connected in the conventional manner.
| Patent | Priority | Assignee | Title |
| 6970075, | Jun 19 2001 | Electronic programmable speed limiter | |
| 7042347, | Jun 19 2001 | Electronic programmable speed limiter |
| Patent | Priority | Assignee | Title |
| 1884951, | |||
| 2753030, | |||
| 3666065, | |||
| 3767972, | |||
| 3789269, | |||
| 3828742, | |||
| 3866584, | |||
| 3875463, | |||
| 3878915, | |||
| 3893108, | |||
| 3993038, | Aug 29 1975 | General Motors Corporation | System for preventing drive train start of a motor vehicle internal combustion engine |
| 4078631, | Apr 02 1976 | Toyota Jidosha Kogyo Kabushiki Kaisha | Apparatus for controlling acceleration and deceleration of motor vehicles |
| 4086647, | Oct 15 1976 | Synchro-Start Products, Inc. | Amplitude responsive speed switch control |
| 4168516, | Oct 15 1976 | Synchro-Start Products, Inc. | Precision speed switch control |
| 4211193, | Feb 10 1977 | Associated Engineering Limited | Speed regulating systems |
| DE2514404, |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Mar 09 1987 | Muncie Power Products, Inc. | (assignment on the face of the patent) | / |
| Date | Maintenance Fee Events |
| Nov 17 1992 | REM: Maintenance Fee Reminder Mailed. |
| Apr 18 1993 | EXP: Patent Expired for Failure to Pay Maintenance Fees. |
| Date | Maintenance Schedule |
| Jun 20 1992 | 4 years fee payment window open |
| Dec 20 1992 | 6 months grace period start (w surcharge) |
| Jun 20 1993 | patent expiry (for year 4) |
| Jun 20 1995 | 2 years to revive unintentionally abandoned end. (for year 4) |
| Jun 20 1996 | 8 years fee payment window open |
| Dec 20 1996 | 6 months grace period start (w surcharge) |
| Jun 20 1997 | patent expiry (for year 8) |
| Jun 20 1999 | 2 years to revive unintentionally abandoned end. (for year 8) |
| Jun 20 2000 | 12 years fee payment window open |
| Dec 20 2000 | 6 months grace period start (w surcharge) |
| Jun 20 2001 | patent expiry (for year 12) |
| Jun 20 2003 | 2 years to revive unintentionally abandoned end. (for year 12) |