Distributor for contactless ignition apparatus for internal combustion engine

Abstract

A distributor for a contactless ignition apparatus of an internal combustion engine is disclosed. An ignition control circuit unit of contactless type is comprised of a case containing the ignition control IC circuit and a mold resin of the pick-up coil integrally formed with the case. The distributor contains closed magnetic circuit-forming means comprising a distributor shaft rotatable in synchronism with the engine, a reluctor or rotor fixed on the shaft and having claws in the number corresponding to the number of engine cylinders, a stator having a pair of claws opposed to the claws of the reluctor and mounted on the movable base of the angle advancer for advancing the ignition timing in response to a negative vacuum pressure, and a permanent magnet for generating a closed magnetic circuit through the reluctor stator and shaft. The pick-up coil of the ignition control circuit unit is arranged to cross the closed magnetic circuit, which unit is fixed within the distributor.

Description

The present invention relates to a distributor for a contactless ignition apparatus for an internal combustion engine, or more in particular to a distributor for the contactless ignition apparatus for the internal combustion engine so constructed that the distributor contains a pick-up coil for detecting the ignition point and a semiconductor control circuit for amplifying an ignition signal and applying it to the igniton coil.

In the contactless ignition apparatus, a small voltage signal generated in the pick-up coil is amplified by an amplifier, the output of which is used to control a semiconductor switch for interrupting the primary current of the ignition coil. As disclosed in U.S. Pat. No. 3,882,840, and ignition control circuit comprising an amplifier circuit and a transistor circuit for detecting the small voltage signal generated from the pick-up coil and a circuit for energizing the switching element are driven by a very low voltage and current thanks to the introduction of integrated circuits.

The pick-up coil is contained within the distributor, while the ignition coil is disposed far away from the distributor, and therefore the pick-up coil, the control circuit and the ignition coil are connected by long wires.

In view of the above-mentioned fact that the control circuit including integrated circuits is driven by a low voltage or current signal, the problem is posed that the ignition timing is disturbed by such noise as a surge voltage of the high-voltage distribution cord and a stray magnetic field from the pick-up coil.

According to a well-known method for solving this problem of noise as disclosed in U.S. Pat. No. 3,888,225, the transistor circuit for detecting the ignition timing signal, the amplifier circuit, the semiconductor switching element and the energization circuit for the switching element are constructed as one electronic circuit unit of several integrated circuits and arranged in the distributor containing the pick-up coil, thus minimizing the wiring length from pick-up coil to the control circuit and within the control circuit.

In this construction with the control circuit incorporated within the distributor, the pick-up coil, the control circuit and the means for forming the closed magnetic circuit are required to be mounted in a limited space. This inconvenience must not lead to the bulkiness of the distributor nor to the difficulty of assembly work.

Another factor to be taken into consideration is the radiation of heat generated by the semiconductor switching circuit in the control circuit.

Accordingly, it is an object of the present invention to provide a distributor for the contactless ignition apparatus in which the pick-up coil, the control circuit unit and the means for forming the closed magnetic circuit are constructed in a simple way to minimize the size of the distributor on the one hand and to facilitate distributor assembly work on the other hand while at the same time taking into consideration sufficient heat radiation from the control circuit.

The feature of the present invention resides in that the IC control circuit of the contactless ignition apparatus is contained in the case formed integrally with the mold resin of the pick-up coil, that a closed magnetic circuit is formed within the distributor by a reluctor or rotor including a permanent magnet, a movable base, a stator and the distributor shaft, that the pick-up coil is arranged in a manner to cross the closed magnetic circuit, and that the case containing the control circuit integrated with the pick-up coil is arranged in a manner to contact a member high in thermal conductivity in the distributor.

According to one aspect of the present invention, there is provided a distributor for the contactless ignition apparatus of the internal combustion engine, comprising a distributor shaft adapted to rotate in synchronism with the engine, a distribution rotor mounted on the top of the shaft, an electrode for receiving power from the distribution rotor, a distributor cap to which the electrode is fixed, a housing combined with the cap to form the outline of the distributor and supporting the distributor shaft at the center thereof, a closed magnetic circuit formed by a permanent magnet in the housing, and means for changing the magnetic fluxes in the closed magnetic circuit at the time of ignition of the engine, the distributor further comprising a contactless ignition control circuit unit including an annular pick-up coil molded of resin, a case integrally coupled to the pick-up coil, and a control circuit module for the ignition control circuit which is contained in the case, the unit being fixedly arranged in such a manner that the pick-up coil crosses the closed magnetic circuit in the distributor and that the case is in contact with a heat conductive member in the distributor.

According to another aspect of the present invention, there is provided a distributor for the contactless ignition apparatus of the internal combustion engine, comprising a reluctor adapted to rotate with the distributor shaft and having a plurality of claws as many as the cylinders, which are formed on the periphery thereof at regular spatial intervals, a stator opposed to the claws and having at least one claw, a movable base carrying the stator, a fixed base for rotatably supporting the movable base and having the periphery thereof fixed to the housing, and a permanent magnet fixed to andwhich, as shown in FIG. 7, includes a signal detection transistor circuit, amplifier circuit, and drive circuit, is actuated and the semiconductor switching element 90 is turned off, thus cutting off the current thus far supplied to the primary winding 107 of the ignition coil through the lead wire 34.

In the process, the high voltage generated at the secondary winding 108 of the ignition coil is introduced to the ignition plug 104 through the central electrode 105 fixed at the center of the cap 2 of the distributor, the rotor electrode of the distribution rotor 100 and the stationary electrodes 102 arranged at regular intervals around the central electrode 105 in the same manner as the engine cylinders. When the next signal is applied to the signal input terminal 81, the distribution rotor has rotated to the position of the next stationary electrode, and therefore the high voltage is introduced to another ignition plug. This operation is repeated as many times as the engine cylinders during the rotation of the shaft.

Upon actuation of an angle advancing mechanism, the timing of forming the gaps G1 and G2 by the claws of reluctor 4 and those of stator 29 occurs before the engine piston reaches the top dead center and therefore an ignition spark is generated before the piston reaches the top dead center. This operation is performed by actuation of either of the angle advancing mechanisms. When the two angle advancing mechanisms are actuated at the same time, the angle advancing effect is doubled.

The present invention may be modified as follows:

1. The pick-up coil and the case containing the control circuit module are formed separately and they are integrally fixed when incorporated in the distributor.

2. Instead of the centrifugal angle advancing mechanism, an electronic angle advancing mechanism is formed in the control circuit and the reluctor is fixed directly on the distributor shaft.

3. The control circuit is provided with an electronic angle delaying device.

The advantage of the present invention is that in spite of the pick-up coil, and the control circuit module being arranged within the distributor, the contactless ignition device made up of them is very simple in construction, so that the distributor is not increased in size nor is the assembly work made difficult.

Claims

1. A distributor for a contactless ignition apparatus of an internal combustion engine having a number of cylinders, comprising: a distributor shaft adapted to rotate in synchronism with the engine; a distribution rotor arranged to rotate together with said shaft; a fixed electrode for receiving power from said distribution rotor; a distributor cap to which said fixed electrode is fixed; a housing combined with said cap to form the outline of the distributor and supporting said distribution shaft at the center thereof; a reluctor arranged to rotate together with said shaft having a number of claws equal in number to the number of engine cylinders and mounted on the periphery of said reluctor at equal spatial intervals; a stator having at least one claw arranged to be opposite to said reluctor claws, a movable base having a semi-circular flange on which said stator is mounted; a fixed base for rotatably supporting said movable base and the periphery of said fixed base being fixed to said housing; a permanent magnet for forming a closed magnetic path in conjunction with said reluctor, said stator, said movable base, and said distributor shaft; an annular pick-up coil coaxially disposed around said distributor shaft and arranged so as to cross a portion of said magnetic path passing through said shaft; a case integrally coupled to said pick-up coil; ignition control means received to said case; and means for supporting, in a cantilever fashion, the pick-up coil, by way of said case, on a portion of said fixed base which is not covered by said movable base.

2. A distributor according to claim 1, wherein a mounting base is fixed on the uncovered portion of said fixed base and said case is fixed on said mounting base to fix said pick-up coil on said fixed base in said cantilever fashion.

3. A distributor according to claim 1, wherein said case is directly fixed on the uncovered portion of said fixed base to fix said pick-up coil to said fixed base in the cantilever fashion.

4. A distributor according to claim 1, wherein said movable base includes a cylindrical portion formed at a central part of a chord of said semi-circular flange, said cylindrical portion being loosely fitted to said shaft, and said permanent magnet, formed in a cylindrical formation, is fixed on the inner surface of said cylindrical portion of said movable base.

5. A distributor according to claim 1, wherein a sleeve is loosely fitted on said shaft, said reluctor being fixed on said sleeve, said sleeve being engaged with a centrifugal angle advancing mechanism, and said pick-up coil being arranged around said sleeve.

6. A distributor according to claim 1, wherein said movable base is movable by a vacuum angle advance mechanism.

7. A distributor according to claim 1, said case being integrally formed by resin for molding said pick-up coil.

8. A distributor according to claim 1, wherein said stator includes a base for fixing said stator on the semicircular flange of said movable base, a pair of arms extending in parallel to said shaft and above a surface of the semi-circular flange of said movable base, and wherein said at least one claw is a pair of claws formed at respective top end portions of said arms arranged to be opposed to the claws of said reluctor, said pair of claws being located on an imaginary line crossing the center point of said shaft.

9. A distributor for a contactless ignition apparatus of an internal combustion engine, comprising a distributor shaft arranged to rotate in synchronism with the engine, a distribution rotor arranged to rotate together with said shaft, an electrode for receiving power from said distributor rotor, a distributor cap to which said electrode is fixed, a housing combined with said cap to form the outline of the distributor and supporting said distribution shaft at the center thereof, a pick-up coil coaxially disposed around said distributor shaft, means for forming a magnetic path crossing to said pick-up coil through said shaft, means for inducing a signal voltage on said pick-up coil by changing the magnetic flux in the magnetic path at an ignition timing, an ignition control circuit for shaping the waveform of the signal voltage, a switching element for switching the current flowing into a primary coil of an ignition coil in accordance with the output of said ignition control circuit, a control circuit module including said ignition control circuit and said switching element which are mounted on a metal base, a resin case integrally connected to said pick-up coil, means for fixing said control circuit module on said resin case such that the metal base forms a portion of an outer wall of said resin case, a heat-dispersion path for dispersing the heat being produced by said switching element to a heat-conductive material within said distributor through said metal base, and means for fixing a contactless ignition device including said resin case having said control circuit module and said pick-up coil to a fixing member within said distributor in such a manner that said contactless ignition device does not touch to any movable member within said distributor.

10. A distributor for a contactless ignition apparatus of an internal combustion engine, comprising a distributor shaft arranged to rotate in synchronism with the engine, a distribution rotor mounted on the top of said shaft, an electrode for receiving power from said distributor rotor, a distributor cap to which said electrode is fixed, a housing combined with said cap to form the outline of the distributor and supporting said distribution shaft at the center thereof, a pick-up coil coaxially disposed around said distributor shaft, means for forming a magnetic path crossing to said pick-up coil through said shaft, means for inducing a signal voltage on said pick-up coil by changing the magnetic flux in the magnetic path at an ignition timing, an ignition control circuit for shaping the waveform of the signal voltage, a power transistor for switching the current flowing into a primary coil of an ignition coil in accordance with the output of said ignition control circuit, a supporting member integrally connected to said pick-up coil for supporting said pick-up coil, said control circuit and said power transistor, a heat-dispersion plate forming a portion of an outer wall of said supporting member, means for connecting said power transistor to an inner wall of said heat-dispersion plate, a heat-conductive member attached to the outer surface of said heat-dispersion plate for forming a heat-dispersion path dispersing the heat produced by said power transistor, means for fixing said heat-conductive member to said housing, and means for fixing a contactless ignition device including said pick-up coil and said supporting member to said heat-conductive member in such a manner that said contactless ignition device does not touch to any movable member within said distributor.

11. A distributor aaccording to claim 10, wherein said supporting member includes terminal plates connected to said ignition control circuit, terminal plates connected to said pick-up coil, means for combining said pick-up coil with said supporting member into an assembly so that contact is made between said terminal plates of said ignition circuit and said terminal plates of said pick-up coil, and means for fixing said assembly of said supporting member and said pick-up coil to a fixing member within said distributor in such a manner that said contactless ignition device does not touch to any movable member within said distributor.

12. A distributor according to claim 11, wherein said assembly includes an output terminal plate for supplying electric current to the primary coil of the ignition coil from said power transistor and a power supply terminal for supplying power to said ignition control circuit and said power transistor.

13. A distributor according to claim 10, wherein a heat-conductive member is fixed on a portion of a fixed base within said distributor and said heat-dispersion plate is in contact with said heat-conductive member to disperse the heat produced by said power transistor to a heat-conductive material within said distributor through said heat-dispersion plate.

14. A distributor according to claim 10, wherein said heat-dispersion plate is indirectly contacted with a fixed base within said distributor.

15. A distributor according to claim 10, wherein said heat-conductive member is a portion of said housing.

16. A distributor for a contactless ignition apparatus, the distributor comprising a housing means, a distributor shaft means rotatably mounted in the housing means, means including a stator means for forming a closed magnetic loop, means for mounting the stator means so as to be adjustably displaceable, a base member fixed to said housing means for rotatably supporting the mounting means for the stator means, an annular pick-up coil means coaxially disposed around said distributor shaft means and arranged to cross a portion of the magnetic loop so as to enable a detecting of changes in the magnetic fluxes occurring in the magnetic loop, an ignition control circuit means operatively connected to said pick-up coil means for interrupting a primary current of an ignition coil means in response to a detection signal generated in the pick-up coil means, and means for mounting the pick-up coil means and said ignition control circuit means of a portion of the fixed base member so as to prevent a relative rotation between the ignition control circuit means and the pick-up coil means. 17. A contactless ignition apparatus comprising a distributor shaft means, an annular pick-up coil means adapted to be coaxially disposed around the distributor shaft means for detecting magnetic fluxes in a magnetic circuit of a distributor, an ignition control circuit module operatively connected to said pick-up coil means for interrupting a primary current of an ignition coil means in response to a detection signal generated in the pick-up coil means, and means for mounting said annular pick-up coil means to the ignition control circuit module so as to enable the annular pick-up coil means to be mounted to a fixed member in the distributor in a cantilevered manner.

18. An apparatus according to claim 17, wherein said means for mounting said annular pick-up coil means includes a case means for accommodating the ignition control circuit means connected to said annular pick-up coil means. 19. An apparatus according to claim 18, wherein said case means is integrally formed of a resin for molding the annular pick-up coil means. 20. An apparatus according to claim 18, wherein said ignition control circuit means includes an ignition signal generator circuit including a signal detection transistor, an amplifier circuit, and a drive circuit means for an output transistor. 21. A distributor for a contactless ignition apparatus of an internal combustion engine having a plurality of cylinders, the distributor comprising: a distributor shaft adapted to be rotated in synchronism with the engine; a distributor rotor arranged to rotate together with said shaft; a fixed electrode for receiving power from said distributor rotors; a distributor cap to which said fixed electrode is fixed; a housing combined with said cap to form the outline of the distributor and supporting said distribution shaft at the center thereof; a reluctor arranged to rotate together with said shaft having a number of claws equal in number to an engine cylinders and mounted on a periphery of said reluctor at equal spatial intervals; a stator having at least one claw arranged in opposition to said reluctor claws; a movable base rotatably supported relative to said housing for mounting said stator; a permanent magnet for forming a closed magnetic path in conjunction with said reluctor, said stator, and continuous metal members existing between said reluctor and said stator; an annular pick-up coil coaxially disposed around said distributor shaft and arranged so as to cross a portion of said magnetic path; a case coupled to said pick-up coil; ignition control means connected to said case; and means for supporting, in a cantilever fashion, the pick-up coil, by way of said case relative to said housing. 22. A distributor for a contactless ignition apparatus, the distributor comprising a housing means, a distributor shaft means rotatably mounted in the housing means, means including a stator means for forming a closed magnetic loop, means for mounting the stator means so as to be adjustably displaceable, a base member fixed to said housing means for supporting the mounting means for the stator means, an annular pick-up coil means coaxially disposed around said distributor shaft means and arranged to cross a portion of the magnetic loop so as to enable a detecting of the changes in the magnetic fluxes occurring in the magnetic loop, an emission control circuit means operatively connected to said pick-up coil means for interrupting a primary current of an ignition coil means in response to a detection signal generated in the pick-up coil means, and means for mounting the pick-up coil means and said ignition control circuit means on a portion of the fixed base member so as to prevent a relative rotation between the ignition control circuit means and the pick-up coil means. 23. A distributor for a contactless ignition apparatus, the distributor comprising a housing means, a distributor shaft means rotatably mounted in the housing means, means including a stator means for forming a closed magnetic loop, means for mounting the stator means so as to be adjustably displaceable, a base member fixed to said housing means for supporting the mounting means for the stator means, and annular pick-up coil means coaxially disposed around said distributor shaft means and arranged to corss a portion of the magnetic loop so as to enable a detecting of changes in the magnetic flux occurring in the magnetic loop, an ignition control circuit means operatively connected to said pick-up coil means for interrupting a primary current of an ignition coil means in response to a detection signal generated in the pick-up coil means, and means for mounting the annular pick-up coil means and said ignition control circuit means on a portion of the fixed base member including a case means for accommodating the ignition control circuit means connected

to said annular pick-up coil means. 24. An apparatus according to claim 23, wherein said case means is integrally formed with a resin for molding the annular pick-up coil means. 25. An apparatus according to claim 23, wherein said ignition control circuit means includes an ignition signal generator circuit including a signal detection transistor, an amplifier circuit, and a drive circuit means for an output transistor.