JP2006002819A - Power supply driving circuit for rotation transmitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply driving circuit for a rotation transmitting device of the electromagnetic clutch type provided on a power transmission path or a wheel of a vehicle to supply sufficient voltage and current enough to switch current carrying and shutting-off in a short time freely. <P>SOLUTION: In this power supply driving circuit for the rotation transmitting device, an electromagnetic clutch controls engagement and shutting-off of a clutch provided with an engaging piece and an elastic member for releasing engagement by the engaging piece between both members using a rear wheel shaft 7 end as an inward member and a hub wheel 18 as an outward member by an electromagnet and the elastic member at a joint position of the rear wheel shaft 7 end and the hub wheel 18 of the vehicle, a power cable P<SB>2</SB>of a feeder circuit for supplying power to the electromagnet through a driver 21 is connected with a battery 22 having high voltage power supply of 36 V above voltage of a battery for starting an engine, and this battery 22 is a battery power supply having capacity for supplying voltage above feeding voltage by which engaging operation from start of engagement to completion of engagement of the electromagnetic clutch is performed within predetermined time and supplying current required for complete engagement to perform engagement and shutting-off operation of the electromagnetic clutch freely at high speed required for a mechanism provided with the rotation transmitting device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  According to the present invention, a rotation transmission device for switching to a 2WD / 4WD on a power transmission path of a vehicle or coupling a wheel such as a free wheel hub and an axle according to a driving state of the vehicle or a driver's intention. The present invention relates to a power transmission circuit for a rotation transmission device for switching with good response.

  As a means for switching between transmission and interruption of power in a vehicle power transmission path or the like, a rotation transmission device using an engagement type electromagnetic clutch is used. As an example, a “rotation transmission device” using an electromagnetic roller clutch according to Patent Document 1 is known. This rotation transmission device switches the engagement and disengagement of the roller clutch with the magnetic force of the electromagnet so that the switching between 4WD and 2WD can be performed smoothly and reliably in the power transmission path of the four-wheel drive vehicle. It is designed to shut off. In this rotation transmission device, a cam surface is formed on one of the opposing surfaces of the shaft end of the input shaft and the outer ring fitted to the input shaft, and a cage having a roller in a pocket is disposed between the opposing surfaces. An electromagnet that engages a switch spring at the end of the cage and attaches a cage and a non-rotatable armature that can move in the axial direction to adsorb the friction member and the armature between the outer ring and the shaft end. Is built in.

  The electromagnetic clutch of the rotation transmission device configured as described above transmits and interrupts power by controlling on / off of energization to the electromagnet. In such a normal usage mode, a switching element such as an FET transistor is inserted as a driver in a circuit that feeds power from an in-vehicle engine starting battery 12V to an electromagnet coil, and switching from a manual switch or a control circuit is performed. A control signal is sent to the switching element to turn on and off the electromagnet. For such a rotation transmission device, it is required to make the rotation transmission device controllable in a short time in order to switch instantaneously to either 2WD / 4WD according to the road surface condition during traveling.

  In addition, the mechanical power transmission mechanism, which has a coupling on the propeller shaft that transmits the engine driving force to the rear wheels, which was essential for the conventional four-wheel drive vehicle 4WD, has been abolished. Non-Patent Document 1 proposes an electric four-wheel drive system that connects a wheel drive motor and drives the rear wheel drive motor with electric power from a generator attached to the engine. This electric four-wheel drive system includes a rear wheel drive unit that amplifies the drive torque of the rear wheel drive motor with a reduction gear and transmits it to the rear wheel axle via a wet multi-plate clutch and a differential gear. The wet multi-plate clutch is of an electromagnetic type and is configured to generate a pressing force of the multi-plate clutch by moving the clutch and the cam mechanism.

  Such an electric four-wheel drive system does not have a function of controlling power distribution to the left and right rear wheels, and power distribution is always performed with equal torque, and the drag resistance of the wet multi-plate clutch cannot be eliminated. There is. Therefore, as means for solving such a problem, the wet multi-plate clutch and the differential gear included in the rear wheel drive unit described above are eliminated, and the rotation transmission device according to Patent Document 1 is installed at both ends of the rear wheel shaft at the left and right rear wheels. It is conceivable to control the driving force distribution by incorporating it into the.

  However, when such a mechanism is realized, the following problem occurs only by incorporating the rotation transmission device of Patent Document 1 into the left and right rear wheels. That is, in order to eliminate the differential gear, it is necessary to absorb the difference in the rotational speed between the left and right rear wheels by each rotation transmission device, and to distribute the driving force by controlling the rotation transmission device on and off. Become. For this reason, energization and disconnection of the rotation transmission device to the electromagnetic clutch are repeated in a short time, and naturally, the transient response time until the electromagnetic clutch is engaged needs to be as short as possible.

However, as described above, in the rotation transmission device of Patent Document 1, a 12V power source is normally used from the engine starting battery, so even if the switching element is turned on and the circuit is closed, the transient response immediately after that is Since the rising speed of the current is slow, it takes a long response time until it is completely engaged, and this is an electromagnetic clutch for applications where energization and shutoff are repeated in a short time like an electric four-wheel drive system. The rotation transmission device cannot be used as it is.
JP 11-336799 A "Automotive Engineering", Railway Japan Co., Ltd., November 2002, pages 46-48

  In consideration of the above problems, the present invention makes it possible to switch between energization and interruption in a rotation transmission device of an electromagnetic clutch type provided on a power transmission path of a vehicle or a wheel in a short time, and to provide a voltage and current with sufficient responsiveness. It is an object to provide a power transmission circuit for a rotation transmission device that can be supplied. In this case, when the rotation transmission device is engaged by the power supply driving circuit, when the engagement is held, on / off control of the circuit prevents heat generation of the electromagnetic clutch and excessive power consumption, thereby saving power. To be able to.

  As a means for solving the above-mentioned problems, the present invention uses both the elastic force of the elastic member and the electromagnetic force of the electromagnet to engage and release the two members by the engagement member fitted between the inner member and the outer member. In a rotation transmission device composed of an electromagnetic clutch to be controlled, a high-voltage power source for driving an electromagnet is connected to a coil of an electromagnet by a power feeding circuit that feeds power through a driver, and a current necessary for complete engagement is obtained from the start of engagement. A battery power source having a capacity capable of supplying a voltage exceeding the engagement time required at the time of repeated operation of engagement and disengagement of the electromagnetic clutch and a current required for the complete engagement. Since the control signal for operating the electromagnetic clutch is input to the drive circuit, the power transmission drive circuit for the rotation transmission device is characterized in that the electromagnetic clutch can be engaged and disconnected freely. That.

  The power transmission drive circuit for the rotation transmission device of the present invention having the above-described configuration is provided in the rotation transmission device in response to a change in the driving state or the driver's intention in the rotation transmission device provided on the power transmission path of the vehicle or on the wheel. Even when the quick engagement of the clutch in a short time required for the engagement or the subsequent engagement and disengagement are repeated in a short time, it is possible to sufficiently secure the engagement and disengagement functions as the clutch. .

  Energization of the electromagnet is performed by connecting a battery power supply having a capacity capable of supplying a voltage and current that are equal to or higher than the voltage of the battery power supply for starting the engine of the vehicle and the transient operation time is within the engagement time. This high-voltage power supply can supply a current necessary for overcoming the elasticity of the elastic member at a high voltage as described above, and can operate in a short time required for the engagement of the rotation transmission device. It is a battery power source with suitable capacity.

  Therefore, this battery power supply is preferably provided independently of the engine starter, but the engine starter may be boosted to the high voltage as described above using a booster circuit. In addition, once the clutch is engaged, it can be maintained even if the attractive force by the electromagnet required to maintain the engaged state is slightly reduced. It is preferable to apply a voltage whose average voltage is smaller by a predetermined percentage than at the time of startup, or to suppress power consumption by PWM control or the like. And by such control, the heat_generation | fever of an electromagnetic coil and excessive power consumption are prevented.

  When a rotation transmission device driven by such a power supply circuit is provided on the rear wheel of the vehicle, the output shaft of the constant velocity universal joint at the rear wheel shaft end is used as an inner member, and the rotation shaft directly connected to the wheel hub is used. The outer member is provided at the fitting position. An engaging member and an elastic member are interposed between the inner member and the outer member so as to release the engagement by the engaging member, and the engaging member engages between both members against the elastic force of the elastic member. In this way, the electromagnet is energized and the attraction force is applied to engage the electromagnetic clutch. When the electromagnet is de-energized, the elastic member elastically returns the clutch to the non-engaged state and is blocked.

  When the above rotation transmission device and its power supply drive circuit are directly incorporated into the rear wheels of the electric four-wheel drive system, the clutch engagement and disengagement can be controlled by sending a control signal from an external control unit. Even if the rear wheel shaft does not have a differential gear by absorbing the difference between the rotational speeds of the left and right rear wheels, traveling by four-wheel drive is possible.

  The power transmission drive circuit for a rotation transmission device according to the present invention is an electromagnetic clutch in which an electromagnetic coil is incorporated in a clutch with an elastic member interposed therebetween, and a large-capacity power source is connected to the electromagnetic coil and repeatedly engaged and disconnected in a short time. Since power is supplied at a current and voltage suitable for the above, the necessary and sufficient clutch switching operation is performed even when switching from two wheels to four wheels or when there is a difference in rotational speed between the left and right wheels during driving. be able to. Moreover, in the engagement holding state after complete engagement, the current and voltage are controlled on and off to prevent the electromagnetic coil from generating heat and preventing excessive power.

A power transmission drive circuit for a rotation transmission device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic block diagram of a power transmission drive circuit for a rotation transmission device. As shown in FIG. 1, the rotation transmission device 10 to be driven according to this embodiment is incorporated in the rear wheels W _RR and W _RL of an FF-based four-wheel drive vehicle (4WD vehicle) A. The 4WD vehicle A is an electric four-wheel drive vehicle and is a junction box (hereinafter abbreviated as TJ / B) for supplying electric power from the generator 3 to the rear-wheel drive motor 4 under the control of the control unit (ECU) 1 of the 4WD. ), And the output is transmitted to the left and right rear wheel shafts 7 and 7 through the speed reducer 6 to drive the rear wheel shafts 7 and 7. The rear wheel shafts 7, 7 are a single shaft that passes through the central gear. 8 is a constant velocity universal joint.

The generator 3 generates power by the power of the engine 9 when the 4WD vehicle A travels, and sends the electric power to the drive motor 4 via the power cable P ₁ via the TJ / B5 to switch between 4WD and 2WD. When 4WD is selected by the switch signal from the 4WD switch 2, electric power is supplied to the motor 4 via TJ / B5. C _F is a line for controlling the field current of each of the generator 3 and the drive motor 4. The energizing current is monitored by an armature, a current sensor and a motor field current sensor (not shown) built in the drive motor 4, and the generator 3 and the motor field current are controlled to respond to the wheel speed difference between the front and rear wheels. Control by the control unit 1 is performed so as to generate the necessary rear wheel drive motor torque.

In the illustrated 4WD vehicle, the differential gear that is normally provided between the gear of the speed reducer 6 and the rear wheel shafts 7 and 7 is omitted. Instead, the rotation transmission device 10 is provided to the left and right rear wheels W _RR and W _RL , respectively. Is provided independently to absorb the difference in rotation speed between the left and right wheels. As shown in FIG. 2, the rotation transmission device 10 is provided independently between the constant velocity universal joints 8 and 8 at the ends of the rear wheel shafts 7 and 7 and the hub wheels 18 and 18, as will be described later. It consists of an electromagnetic clutch that engages and disengages a clutch including a roller as an engagement element by an electromagnet. The structure of the rotation transmission device 10 will be described with reference to FIG. Hereinafter, the one-side rotation transmission device 10 will be described. 2A is a main cross-sectional view of the rotation transmission device 10, and FIG. 2B is a cross-sectional view taken along line BB in FIG.

  The rotation transmission device 10 has the same basic configuration as that disclosed in Patent Document 1, but is completely different in use state. As shown in the figure, this rotation transmission device 10 uses a stem portion 8a of the constant velocity universal joint 8 as an inner member, and a plurality of rollers 12 corresponding to a plurality of pockets of a cage 11 fitted to the outer periphery thereof. And a clutch 10 a in which the outer member 13 is fitted to the outside of the roller 12, and an electromagnet 16 provided on the outer periphery of the outer member 13. At one end of the retainer 11 (the left end in FIG. 2A), an armature 14 is integrated with the retainer 11 in the circumferential direction, and is provided so as to be slightly movable relative to the retainer 11 in the axial direction. The armature 14 is disposed to face the flange portion 13a at one end (left end) of the outer member 13.

  A separation spring 15 made of an elastic member such as a disc spring is provided between the armature 14 and the flange portion 13a, and both are always biased in a direction away from each other. A plurality of cam surfaces 8 c are provided on the outer periphery of the stem portion 8 a of the inner member corresponding to each roller 12, and based on a wedge-shaped space formed between each cam surface 8 c and the inner peripheral surface of the outer member 13. When the roller 12 is positioned at the center of the cam surface 8c, a slight gap is generated between the roller 12 and the inner peripheral surface of the outer member 13, and the roller 12 is moved to either end of the cam surface 8c. The rotation of the stem portion 8 a of the inner member is transmitted to the outer member 13 through the roller 12.

  As shown in FIG. 2B, the switch spring 17 described above is held in a groove provided on the end surface of the retainer 11 opposite to the armature 14, and is formed on the shoulder portion of the stem portion 8a. The tip of the switch spring 17 is inserted into a notch formed in a part in the circumferential direction on both the peripheral wall of the groove and the retainer 11. As long as the electromagnet 16 is not energized, the switch spring 17 acts so that the roller 12 is positioned at the center of the cam surface 8c by the elastic force. When the electromagnet 16 is energized, the armature 14 is attracted by the attraction force, and the armature 14 is integrated with the cage 11 with respect to the rotation, and is frictionally engaged with the flange portion 13 a of the outer member 13.

  When the stem portion 8a of the inner member rotates in any direction, the rotational force is transmitted from the retainer 11 and the armature 14 to the flange portion 13a of the outer member 13 by the friction engagement. Therefore, the rotation of the retainer 11 is slightly delayed with respect to the rotation of the stem portion 8a, whereby the phase of the notch of the shoulder portion of the retainer 11 and the stem portion 8a is slightly shifted, and the tip of the switch spring 17 is pushed, The roller 12 approaches the end of the wedge space opposite to the direction in which the stem portion 8a advances. For this reason, the stem portion 8 a is engaged with the roller 12, and the rotation is directly transmitted to the outer member 13 through the roller 12. When the energization of the electromagnet 16 is interrupted, the armature 14 is separated from the retainer 11 and the flange portion 13a, and the roller 12 is returned to the neutral position by the elastic force of the switch spring 17, and the rotation is interrupted.

With respect to the electromagnet 16 of the rotation transmission device 10, as shown in FIG. 1, in this embodiment, a required current at a high voltage is supplied from a dedicated battery 22, which is a high voltage power source, via a driver 21 through a power cable P ₂ of a power feeding circuit. Are connected to be supplied with power. In the illustrated example, the battery 22 is a battery that can supply a large current of 20 A at a voltage of 36 V, and is provided separately from a 12 V battery for a normal vehicle that starts the engine 9 and drives other auxiliary machines. It is. For the driver 21, for example, a switching element such as an FET transistor is used.

  FIG. 3 shows an example of a circuit for supplying power to the coil 23 of the electromagnet 16 of the electromagnetic clutch. The driver 21 is provided on the cathode side of the coil 23, but may be provided on the anode side. Reference numeral 24 denotes a free-wheeling diode for a counter electromotive voltage discharge circuit. Further, since the coil is represented by a series equivalent circuit of a resistance R and an inductance L, the necessary electromagnetic force is set by setting the value to an appropriate value. In the illustrated example, the resistance value R = 3.25Ω and the inductance value 0.09H.

The control unit 1 of the 4WD, as described in FIG. 1, the generator 3, by controlling the field current of the drive motor 4, the rear wheel shaft and turn on the TJ / B5 by the control line C ₅ under 4WD control 7 and 7 are driven to rotate, and when the rotational speed difference between the left and right rear wheels W _RL and W _RR occurs during traveling, the electromagnetic clutches of the rotation transmission devices 10 and 10 for the left and right rear wheels are independently turned on to absorb this difference. The control line C ₂₁ is connected to the drivers 21 and ₂₁ so as to perform the off control. Further, in the control unit 1, each electromagnetic clutch is connected and energized for a certain time when the engagement is started in the transient response, and then PWM control unit for performing PWM (Pulse Width Modulation) control in order to suppress power consumption in the engagement holding. As a built-in program.

  In the power transmission drive circuit for the rotation transmission device of the embodiment configured as described above, the rotation transmission device is driven as follows by controlling the electromagnetic clutch as necessary during traveling of the vehicle. When 4WD control is started by a switch signal from the 4WD switch 2, the electromagnetic clutch is turned on by a signal for engaging the electromagnetic clutch. At this time, the engaging operation as the electromagnetic clutch is performed in the following order. That is, the switching element of the driver 21 is turned on, a current flows through the electromagnet, and the electromagnet generates an attractive force (electromagnetic force). The suction force overcomes the elastic force of the separation spring 15 and the armature 14 comes into contact with the flange portion 13a of the outer member 13 which is a rotor.

  As a result, a frictional force is generated between the armature 14 and the flange portion 13a. At the same time, the armature 14 is integrated with the cage 11 by the movement of the armature 14 in the axial direction, and the rotation of the stem portion 8 a of the inner member is transmitted to the armature 14 through the cage 11. For this reason, the armature 14 and the outer member 13 are out of phase and press the switch spring 17, and the friction torque overcomes the switch spring 17. As a result, the roller 12 moves to the engagement position of the wedge space with a phase delay, and the rotation of the inner member is directly transmitted to the outer member 13.

Therefore, the time required for engaging the electromagnetic clutch depends on the rise time t _A until the attraction force to the armature 14 reaches a predetermined current required to overcome the separation spring 15 and the switch spring 17 and the phase shift of the armature 14. This is the total (clutch engagement time) with the movement time t _B of the roller 12 to the engagement position. Since the movement time t _B depends on the relative rotational speed of the inner member and the outer member 13, it is irrelevant to the current of the electromagnet, but the rise time t _A becomes shorter as the current increases.

FIG. 4 shows the relationship between the rise time t _A and the voltage and current values. FIG. 4 shows an example using battery power supplies of 12V and 36V, and shows that the operating time is shorter at 12V than at 36V. This figure also shows the change in current value when the electromagnet is further energized after the clutch is completely engaged. Therefore, for example, when the current is 20A and the necessary and sufficient suction force is generated and fully engaged, about 5 ms is sufficient for the 36V power supply, while 20 ms is required for the conventional 12V battery for engine starting. You can see what it takes.

  As shown in the example, when the rotation transmission device 10 provided on the rear wheel without a differential gear repeatedly energizes and shuts off the electromagnetic clutch for distributing the driving force, in order to realize the operation smoothly. In general, it is considered that the transient response time until the clutch is fully engaged should be 10 ms or less. However, from the conclusion shown in FIG. 4, the rated voltage 12 V of the conventional battery power source for starting the engine is not sufficient. It is understood that the voltage should be higher or more than several times.

  Actually, for example, after reaching 20 A, the control signal is temporarily turned OFF so that no excessive current flows any more, and thereafter, as shown in FIG. PWM control that repeats ON and OFF is performed. The necessity for such PWM control is as follows. That is, the amount of current required for the initial armature 14 suction (proportional to the suction force) is as described above, but the amount of current required after the suction is reduced below that (FIG. 5B). reference).

  The pulling force of the separation spring 15 for releasing the engagement increases proportionally as the distance is shortened according to the Hooke's law. However, the attracting force by the electromagnet increases as the position of the armature 14 approaches the electromagnet (according to Coulomb's law). On the basis of the square of the distance, i.e., at a rate greater than the increase in the separating force of the separating spring). Therefore, the attraction force of the electromagnet required after the armature 14 is attracted may be smaller than the attracting force necessary at the start of the attraction.

  As described above, since the attractive force may be reduced after the armature 14 is attracted, when the voltage is suppressed by PWM control, the switching element is repeatedly turned on and off at a time equal to or less than the time constant obtained from the resistance and inductance of the coil. If the time is set, the voltage can be controlled according to the ON time. Also, if a continuous energization state is maintained without PWM control, a large amount of power consumption is required, so that the power consumption is directly converted into thermal energy and the electromagnet generates heat to avoid shortening the durability of the electromagnet. It is preferable to suppress the power to the minimum necessary. Therefore, in the engagement holding state after the electromagnetic clutch is engaged, the power is suppressed to the minimum to prevent heat generation.

  In the illustrated example, the battery 22 is described as a 36V power source and a power source independent of the engine starting battery is used. However, the rated output voltage 12V of the engine starting battery is used as the power source, and its output terminal and driver are used. A voltage boosting circuit for boosting a voltage such as a DC-DC converter may be inserted between the voltage 21 and the high voltage such as 36V. In addition, it has been shown that a 36V high-voltage power supply is suitable for an application in which the rear wheel of the illustrated four-wheel drive vehicle is repeatedly engaged and disconnected at high speed as an independent battery power supply. In general, the time allowed for complete engagement of the electromagnetic clutch is 10 ms (0.01 seconds) or less, and the current value (for example, 20 A) required for complete engagement is within this allowable time. The possible high voltage is at least 30V or more, and if possible, it may be 36V or more. In addition, when a high voltage power source such as a 36V rated output voltage of the battery for starting the engine is used as the power source, the battery 22 may be shared.

  In the above embodiment, the power supply drive circuit of the example in which the rotation transmission device 10 is applied to the rear wheels of the four-wheel drive vehicle has been described. However, the rotation transmission device 10 is mounted on the propeller shaft that transmits the engine driving force to the rear wheels in a conventional vehicle. The rotation transmission device 10 can also be provided for various other purposes. In each case, the above-mentioned power supply drive circuit is provided and the electromagnetic clutch is installed in an application where it is necessary to repeatedly engage and disengage the electromagnetic clutch. It is effective to control.

  The power transmission drive circuit for a rotation transmission device according to the present invention can supply a power supply voltage capable of operating the engagement and disengagement of the electromagnetic clutch at a high speed. Can be widely used for mechanisms that need to be operated at high speed.

Whole schematic block diagram of application example of power transmission drive circuit for rotation transmission device to electric four-wheel drive vehicle of embodiment (A) Main sectional view of structural drawing of rotation transmission device of embodiment, (b) Cross sectional view of arrow BB Detailed view of power transmission drive circuit for rotation transmission device of FIG. Explanatory drawing of the relationship between the engagement rise time of the electromagnetic clutch and the current Illustration of relationship between electromagnetic clutch engagement and PWM control

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 4WD switch 3 Generator 4 Drive motor 5 Junction box 6 Reducer 7 Rear-wheel shaft 8 Constant velocity universal joint 9 Engine 10 Rotation transmission apparatus 11 Cage 12 Roller 13 Outer member 14 Armature 15 Retraction spring 16 Electromagnet 17 Switch Spring 18 Hub wheel 21 Driver 22 Battery 23 Coil

Claims (8)

  In a rotation transmission device including an electromagnetic clutch that controls engagement and release of both members by an engagement member fitted between an inner member and an outer member by an elastic force of an elastic member and an electromagnetic force of an electromagnet. A high-voltage power source for driving is connected to the coil of the electromagnet by a power feeding circuit that feeds power through a driver, and the transient operation time from the start of engagement to the current required for complete engagement is at least engaged with the electromagnetic clutch, A control signal for operating the electromagnetic clutch is input to the driver using a battery power source with a capacity capable of supplying the voltage exceeding the engagement time required for repeated disconnection operations and the current required for complete engagement. Thus, the power transmission drive circuit for the rotation transmission device can freely engage and disengage the electromagnetic clutch.   2. The rotation transmission device according to claim 1, wherein the high-voltage power supply is a battery for starting an engine of a vehicle, and its output voltage is boosted to a required voltage by a booster circuit provided in a power feeding circuit. Power supply drive circuit.   The power supply for a rotation transmission device according to claim 1 or 2, wherein a control unit for controlling the electromagnetic clutch is provided, and a control signal is sent to a driver to control engagement and disconnection of the electromagnetic clutch. Driving circuit.   4. The control unit according to claim 3, wherein a control signal is sent to a driver to control energization on and off at predetermined time intervals when maintaining the engagement after the electromagnetic clutch is completely engaged. A power supply drive circuit for a rotation transmission device according to 1.   5. The power transmission drive circuit for a rotation transmission device according to claim 4, wherein on / off control in the engagement holding state of the rotation transmission device by the control unit is PWM controlled via the PWM control unit.   The rotation transmission device is provided between the axle end of the vehicle and the wheel hub, and each electromagnetic clutch is controlled to be turned on and off by a control signal from the control unit to absorb the difference in rotational speed between the left and right ends. 6. The power transmission circuit for a rotation transmission device according to claim 3, wherein the power transmission circuit is adjustable.   The rotation transmission device is provided between the axle end of the rear wheel of the vehicle and the wheel hub, and is connected to the control unit so as to input a signal of a changeover switch of 4WD and 2WD. 7. The power transmission drive circuit for a rotation transmission device according to claim 6, wherein the drive is free.   An electromagnetic clutch of the rotation transmission device includes a roller clutch in which a plurality of engaging rollers are inserted in a pocket of a cage provided between an outer member and an inner member having a plurality of cam surfaces on an outer peripheral surface thereof, It consists of an electromagnet on the outside, an armature provided at the end of the cage, and an electromagnetic unit having a switch spring provided at the end opposite to the armature of the inner member. The armature is integrated with the inner member in the rotational direction. 8. The switch spring according to claim 1, wherein the switch spring is provided so as to be movable in an axial direction, and the retainer is provided so as to apply an elastic force so that the roller is positioned at the center of the cam surface. A power supply drive circuit for a rotation transmission device according to claim 1.

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