JP2003312302A - Vehicle driving force distribution control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle driving force distribution control system for inhibiting heat generation of a switching element at a lower cost. <P>SOLUTION: In the vehicle driving force distribution control system 90, the duty ratio of the pulse voltage generated as an FET71 is driven is lowered when an engine 10 is stopped, and the current running in the FET71 is reduced, and therefore, the quantity of heat generation of the FET71 is controlled. Accordingly, the heat generation of the FET can be inhibited at a low cost without upgrading the specification of the FET or adding a new cooling means as before. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel driving force distribution control system for changing the torque transmitted to wheels other than the constantly driving wheels of an automobile according to the situation.

[0002]

2. Description of the Related Art Recent four-wheel drive vehicles are equipped with a torque transmission device in the middle of a propeller shaft that connects an engine and rear wheels, for example, to drive the front wheels at all times and the rear wheels according to the situation. It has become. The torque transmission device can change the coupling strength between the input-side propeller shaft that interlocks with the front wheels and the output-side propeller shaft that interlocks with the rear wheels by the magnetic force of the electromagnetic coil. Then, the ECU provided in the automobile generates a pulse voltage by driving the switching element and applies it to the electromagnetic coil, and controls the transmission torque of the torque transmission device by the duty ratio of the pulse voltage.

[0003]

By the way,
It may be left for a long time with the ignition turned on while the engine is stopped. However, conventionally, even when the engine is stopped, the switching element is driven in the same manner as when the engine is operating.
When the accelerator is stepped on while the engine is stopped, the switching element is repeatedly turned on and off in response to this, and there is a concern that the switching element may generate heat over time. Therefore, conventionally, in order to suppress heat generation, the cost of the switching element has been increased, such as increasing the specifications of the switching element and strengthening the cooling function.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel driving force distribution control system that is less costly than conventional ones and that can suppress heat generation of switching elements.

[0005]

SUMMARY OF THE INVENTION A wheel driving force distribution control system according to the invention of claim 1 made to achieve the above object comprises an input section which rotates in conjunction with a constantly driving wheel of an automobile, and a continuously driven vehicle. It has an output unit that rotates in conjunction with wheels other than the wheels, and changes the connection strength between the input unit and the output unit by changing the electric current input to the connection strength control unit. A torque transmission means capable of changing the transmission torque, a transmission torque control means for generating a pulse voltage of a predetermined cycle by driving a switching element, and controlling the transmission torque of the torque transmission means by a duty ratio of the pulse voltage, and an engine of an automobile An engine stop determination means for determining whether or not the engine is stopped, and the transmission torque control means determines whether the engine has stopped based on the determination result of the engine stop determination means. In has a characteristic than that in the operation of the engine, to a location that the sleep mode having a reduced current input to the connection strength control unit.

The "always driven wheel" in the present invention means a wheel which is constantly driven by a driving force when the automobile is running.

According to a second aspect of the present invention, in the wheel driving force distribution control system according to the first aspect, the transmission torque control means holds the current input to the connection strength control unit at 0 in the idle mode. Have.

A wheel driving force distribution control system according to a third aspect of the present invention has an input section that rotates in conjunction with the constantly driving wheels of an automobile, and an output section that rotates in conjunction with wheels other than the constantly driving wheels. Then, the connection strength between the input section and the output section is changed, and the current input to the connection strength control section is changed to change the transfer torque from the input section to the output section. Transmission torque control means for generating a pulse voltage of a predetermined cycle by driving and controlling the transmission torque of the torque transmission means by the duty ratio of the pulse voltage, and engine stop determination for determining whether or not the engine of the automobile is stopped. The transmission torque control means, based on the determination result of the engine stop determination means, determines the frequency of the pulse voltage when the engine is stopped compared to when the engine is operating. Having the features in place to become a pause mode having a reduced number.

According to a fourth aspect of the present invention, in the wheel driving force distribution control system according to any one of the first to third aspects, the transmission torque control means has a predetermined time elapsed while the duty ratio is larger than a predetermined threshold value. It has a feature that it goes into sleep mode only occasionally.

According to a fifth aspect of the present invention, in the wheel driving force distribution control system according to any one of the first to third aspects, the transmission torque control means is such that the average current input to the connection strength control section is lower than a predetermined threshold value. The feature is that the sleep mode is set only when a predetermined time has passed in a large state.

According to a sixth aspect of the present invention, in the wheel driving force distribution control system according to any one of the first to third aspects, the engine stop determination means is a vehicle speed detection means for detecting a vehicle speed of the vehicle and a throttle opening of the vehicle. The engine is stopped when a predetermined time has elapsed while the vehicle speed is 0 and the throttle opening is equal to or more than a predetermined threshold value. There is a feature in doing.

According to a seventh aspect of the present invention, in the wheel driving force distribution control system according to any of the first to third aspects, the engine stop determination means detects whether or not the engine is stopped by detecting the engine speed. It has a feature in that it distinguishes.

[0013]

<Invention of Claim 1><Invention of Claim 1> According to the wheel driving force distribution control system of Claim 1, when the engine is stopped, compared to when the engine is operating, the current flowing through the coupling strength control unit and the switching element are applied. Since the flowing current is reduced, heat generation of the switching element is suppressed. That is, according to the present invention, since heat is not generated without increasing the specifications of the switching element or adding a new cooling means as in the conventional case, a low-cost switching element can be used.

<Invention of Claim 2> According to the wheel driving force distribution control system of Claim 2, in the engine stopped state, the switching element is stopped in order to keep the current flowing through the coupling strength control unit at zero. Heat generation of the switching element is suppressed.

<Invention of Claim 3> According to the wheel driving force distribution control system of Claim 3, the frequency of the pulse voltage is reduced when the engine is stopped as compared with when the engine is operating. Therefore, the amount of heat generation is suppressed. That is, according to the present invention, it is possible to suppress heat generation of the switching element at low cost without increasing the specifications of the switching element and adding new cooling means as in the conventional case.

<Invention of Claim 4> According to the wheel driving force distribution control system of Claim 4, the predetermined time does not elapse in a state where the duty ratio is larger than the predetermined threshold value.
Thereby, heat generation of the switching element can be suppressed.

<Invention of Claim 5> According to the wheel driving force distribution control system of Claim 5, a predetermined time may elapse in a state in which the average current flowing through the coupling strength control unit and the switching element is larger than a predetermined threshold value. As a result, heat generation of the switching element can be suppressed.

<Invention of Claim 6> According to the configuration of Claim 6, the engine is stopped when the vehicle speed is 0 and the throttle opening is equal to or greater than a predetermined threshold value for a predetermined time. Since the determination is made, it is not necessary to provide a means for directly detecting the presence or absence of engine rotation.

<Invention of Claim 7> According to the configuration of Claim 7, since it is determined that the engine is stopped when the engine speed is 0, it is possible to reliably detect the engine stop.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION <First Embodiment> A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a main part of a drive system of an automobile. On the front side (left side in FIG. 1) of this automobile, a trans-ask 11 is provided adjacent to the engine 10. The trans-ask 11 is integrally assembled with a transmission, a transfer, and a front differential 12. . Then, the driving force of the engine 10 is transmitted to the front wheel driven shafts 13, 13 via the transmission of the trans-ask 11 and the front differential 12, and the front wheels 14, 14 are driven. That is, in the present embodiment, the front wheels 14 and 14 correspond to the “always-driving wheels” of the present invention which are driven by receiving the driving force when the vehicle is running.

The transmission of the transfer axle 11 gear-connects the transmission with the front end portion of the front propeller shaft 20. A rear end portion of the front propeller shaft 20 is located at an intermediate portion in the front-rear direction of the automobile and serves as an input portion 31 (see FIG. 2) of the torque transmission device 30 (corresponding to “torque transmission means” of the present invention). It is fixed. As a result, the input unit 31 of the torque transmission device 30 constantly rotates in association with the front wheels 14 and 14 as driving wheels.

A rear propeller shaft 21 extends on an extension line of the front propeller shaft 20 with the torque transmission device 30 interposed therebetween, and a front end portion of the rear propeller shaft 21 has an output portion 32 ( (See FIG. 2). Further, the rear end portion of the rear propeller shaft 21 is connected to the rear differential 17, and the rear wheel driven shafts 16, 16 extending from the rear differential 17 in both the left and right directions are attached to the rear wheel 1.
5, 15 are attached. As a result, the output unit 32 of the torque transmission device 30 rotates in conjunction with the rear wheels 15, 15 as "wheels other than the constantly driven wheels" of the present invention.

FIG. 2 shows the basic structure of the torque transmission device 30. The input unit 31 of the torque transmission device 30 is
A cylindrical outer case 33 having a bottom with one end having a bottom wall 33T on the front side (that is, the front side of the automobile) is provided, and at the tip of a shaft portion 33J extending from the center of the bottom wall 33T to the front side, The front propeller shaft 20 (see FIG. 1) is fixed. On the other hand, a rear cover 35 is fitted and screwed to the inside of the open end of the outer case 33, and an inner shaft 34 that constitutes the output portion 32 is liquid-tight in a through hole 35A formed in the center of the rear cover 35. Has penetrated into the state.

The inner shaft 34 is rotatably supported with respect to the outer case 33 with its axial movement restricted, and one end of the inner shaft 34 extends to the inner depth of the outer case 33. The other end projects outward from the outer case 33 and is fixed to the rear propeller shaft 21 (see FIG. 1).

At a position near the rear cover 35 in the outer case 33, a first cam disk 36 is provided with an inner shaft 34.
Is rotatably fitted to the inner pilot clutch plate 37.
Are spline fitted. Also, the outer case 3
A plurality of outer pilot clutch plates 38 are spline-fitted to a position near the rear cover 35 on the inner peripheral surface of 3,
Each inner and outer pilot clutch plate 3
7, 38 are alternately arranged and face each other in the axial direction. Further, a disc-shaped armature 49 is spline-fitted to the inner peripheral surface of the outer case 33 at a position where the group of pilot clutch plates 37 and 38 are sandwiched between the rear cover 35 and the rear cover 35. Further, always, between the armature 49 and the rear cover 35, the inner and outer pilot clutch plates 37, 38 are separated from each other and can freely rotate with respect to each other.

An electromagnetic coil 39 (corresponding to a "coupling strength control section" according to the present invention) is arranged outside the outer case 33, behind the rear cover 35. The electromagnetic coil 39 is housed inside an annular groove formed in the front surface of an annular yoke 39A, and the yoke 39A is rotatably supported by the rear cover 35 by a bearing (not shown). Then, by exciting the electromagnetic coil 39, the pilot clutch plates 37 and 38 are pulled together with the armature 49 toward the rear cover 35, and the inner and outer pilot clutch plates 37 and 38 are frictionally engaged with each other. Further, as the magnetic force of the electromagnetic coil 39 is increased, the engagement of both pilot clutch plates 37, 38 deepens, and when the engagement is deepest, the pilot clutch plates 37, 38 are integrally connected, that is, a so-called direct connection state. . Due to the frictional engagement or direct connection between the two pilot clutch plates 37 and 38, the first cam disc 36 receives the rotational torque from the outer case 33 and rotates.

V-shaped recesses 40 are formed on the front surface of the first cam disk 36 at a plurality of locations along the circumferential direction. Figure 3
A cross-sectional view of the V-shaped recess 40 as viewed from the radial direction of the first cam disk 36 is shown in (A). As shown in FIG.
The shaped recess 40 is recessed in a V shape so as to become gradually deeper toward the center in the width direction (the vertical direction in FIG. 3A).
Further, the second cam disc 41 is provided on the front side of the first cam disc 36 (the left side in FIGS. 2 and 3 (A)) with the inner shaft 34.
Is spline-fitted to the outer surface of the second cam disk 41, and the second cam disk 41 has a V-shaped recess 40 symmetrical to the V-shaped recess 40 of the first cam disk 36.
A shaped recess 42 is formed. Then, when the cam ball 43 is held by being sandwiched between the both V-shaped recesses 40 and 42, and the first cam disc 36 rotates, FIG.
As shown in FIG. 5, the cam ball 43 moves to a shallow position in the V-shaped recesses 40 and 42, and the first and second cam discs 3
A force is generated in the direction in which the parts 6 and 41 are separated from each other. Further, the first cam disc 36 is restricted from moving in the axial direction by an abutting portion (not shown), so that when the first cam disc 36 rotates, the second cam disc 41 moves forward. Pressed to move.

As shown in FIG. 2, a plurality of inner main clutch plates 44 are spline-fitted to the outer peripheral surface of the inner shaft 34 on the front side of the second cam disc 41 in the outer case 33, and a plurality of inner main clutch plates 44 are also provided. The outer main clutch plate 45 is spline-fitted to the inner peripheral surface of the outer case 33. The inner and outer main clutch plates 44, 45 are alternately arranged and face each other in the axial direction, and the inner and outer main clutch plates 44, 45 are always separated from each other and freely rotatable. It is in a state of. Then, as described above, the inner and outer main clutch plates 44 and 45 are pushed toward the bottom wall 33T side of the outer case 33 by the second cam disc 41 that has moved forward due to the magnetic force of the electromagnetic coil 39. Frictionally engage with each other, and these main clutch plates 44,
Torque is transmitted from the outer case 33 to the inner shaft 34 via 45. Further, due to the increase in the magnetic force of the electromagnetic coil 39, the pressing force of the second cam disc 41 increases, and the frictional engagement between the main clutch plates 44 and 45 deepens. When the engagement is deepest, the main clutch plates 44, 45 are in a so-called direct connection state in which they are integrally connected.

To summarize the above, in the torque transmission device 30, the input section 31 and the output section 32 allow a freely rotatable mutual disconnection state and a rotation difference between the input section 31 and the output section 32. Meanwhile, it is possible to change to a state in which a predetermined torque is transmitted from the input unit 31 to the output unit 32, and further to a direct connection state in which the input unit 31 and the output unit 32 are completely connected.

The electromagnetic coil 39 is driven by the ECU.
50 (corresponding to the “transmission torque control means” of the present invention), and the ECU 50 and the torque transmission device 30.
Therefore, the wheel driving force distribution control system 90 according to the present invention
(See FIG. 1).

As shown in FIG. 4, the ECU 50 is provided with a drive circuit 74 connected to the microcomputer 70. Also, the ECU
Reference numeral 50 denotes, for example, a power MOS- for power switching.
A switching circuit using an N-channel FET 71 (hereinafter, simply referred to as “FET 71”) is provided. The gate terminal of the FET 71 is connected to the output of the drive circuit 74, the source terminal of the FET 71 is connected to the ground (for example, the negative electrode of the battery 75), and the FET 71 is connected.
The drain terminal of is connected to one terminal of the electromagnetic coil 39 provided in the torque transmission device 30. The other terminal of the electromagnetic coil 39 is connected to the positive electrode of the battery 75, so that when the FET 71 is turned on in the drive circuit 74, a current flows from the battery 75 to the electromagnetic coil 39, and Be excited.

A relay 73 is provided between the electromagnetic coil 39 and the battery 75 together with the noise filter 72. The relay 73 is opened / closed when the ignition is turned on / off, for example. Further, a diode 78 for opening back electromotive force when the FET 71 is turned off is connected between both terminals of the electromagnetic coil 39, and a current sensor 76 is provided at one terminal of the electromagnetic coil 39. There is. Then, the detection result of the current sensor 76 is taken into the microcomputer 70 through the A / D converter 77.

The ECU 50 generates a pulse voltage by driving the above-mentioned FET 71 and applies it to the electromagnetic coil 39,
By changing the duty ratio of the pulse voltage,
By changing the current flowing through the electromagnetic coil 39, the transmission torque of the torque transmission device 30 is controlled. Here, the “duty ratio” means the ratio of the pulse width to one cycle (= 1 / frequency) of the pulse voltage.

The ECU 50 determines the torque command value of the torque transmission device 30 according to various situations. In order to determine the various situations, the ECU 50 has a throttle opening m detected by the throttle sensor 60 as shown in FIG.
And the engine rotational speed EN detected by the tachometer 62 and the front wheels 14, 1 detected by the rotational speed sensor 61.
The rotational speeds N1 and N2 of 4 and the rotational speeds N3 and N4 of the rear wheels 15 and 15 are taken in. And each sensor 6
In order to determine the torque command value from the detection signals of 0, 61, and 62, the ECU 50 reads the main program M from a ROM (not shown) at a predetermined cycle and runs it, and at the same time, outputs the output program K1 to the ROM. Read from and run.

In the main program M, as shown in FIG. 4, first, the throttle opening m and the wheels 14, 14, 1 are set.
The rotational speeds N1 to N4 of 5, 15 are taken into the ECU 50 (S1). Then, the vehicle speed V and the rotational speed difference ΔN between the front and rear wheels 14, 15 are calculated and obtained (S2, S3). Here, the vehicle speed V is obtained as an average value of the rotational speeds of the rear wheels 15 and 15 which are driven wheels, for example, as shown in the following formula (S2).

V = (N3 + N4) / 2

On the other hand, the rotational speed difference ΔN is obtained by subtracting the sum of the rotational speeds of the two rear wheels 15 and 15 from the sum of the rotational speeds of the two front wheels 14 and 14 and dividing the result into two as shown in the following equation. Required (S3).

ΔN = (N1 + N2-N3-N4) / 2

Next, the pre-torque Tp is calculated (S
4). Specifically, the pre-torque Tp is obtained from the throttle opening m and the vehicle speed V based on a map stored in a ROM (not shown) provided in the ECU 50.

Next, the rotational difference torque Tn is calculated (S
5). Specifically, the rotation difference torque Tn is obtained from the rotation speed difference ΔN and the vehicle speed V based on a map stored in a ROM (not shown).

Next, a torque command value Ta (= Tp + Tn) which is the sum of the pre-torque Tp and the rotation difference torque Tn.
And the map stored in the ROM (not shown), the command value I of the current flowing through the electromagnetic coil 39 is determined, and the main program M is exited.

The output program K1 which runs next to the main program M is shown in FIG. In the output program K1, first, based on the output of the tachometer 62, it is checked whether or not the rotation speed of the engine 10 is larger than 0 (S11: corresponds to "engine stop determination means" according to the present invention). That is, it is checked whether the engine 10 is operating or stopped. Then, when the engine 10 is operating (Yes in S11), normal output control is performed (S15).

That is, the duty ratio of the pulse voltage applied to the electromagnetic coil 39 is determined and applied to the drive circuit 74 so that the current according to the current command value I obtained by the main program M is passed through the electromagnetic coil 39. Then, the drive circuit 7
4 is a FET for generating a pulse signal of the duty ratio
It outputs to the gate terminal of 71. Thereby, the pulse voltage is applied to the electromagnetic coil 39, and at this time, the electromagnetic coil 39
The average value of the currents flowing in the area becomes the magnitude corresponding to the current command value I, and the transmission torque corresponding to the torque command value Ta is transmitted from the input unit 31 of the torque transmission device 30 to the output unit 32.

On the other hand, when the engine 10 is stopped (No in S11), it is checked whether the duty ratio determined based on the current command value I is equal to or more than a predetermined threshold value (S12). If the duty ratio is smaller than the threshold value (No in S12), the load on the FET 71 is also small, and thus normal output control is performed (S15). If the duty ratio is equal to or greater than the threshold value (Yes in S12), it is checked whether the predetermined time T has elapsed. Specifically, first, when it is detected that the duty ratio is equal to or greater than the threshold value, the timer on the program is started, and each time the output program K1 runs at a predetermined cycle, the time for that cycle is incremented and elapsed. Time is measured. Then, it is checked whether or not this elapsed time exceeds the predetermined time T.

Here, even when the duty ratio is equal to or more than the threshold value, when the predetermined time T has not elapsed (S1
No in 3), and since the load on the FET 71 is small, the normal output control described above is performed (S15). On the other hand, when the predetermined time T elapses in the state where the duty ratio is equal to or higher than the threshold value (Yes in S13), the FET 71 may generate heat, so the duty ratio is reduced to, for example, the threshold value or lower (S1).
4). That is, the ECU 50 enters the "pause mode" according to the present invention.

The configuration of this embodiment is as described above. Next, the operation and effect of this embodiment will be described. The ignition may be turned on while the engine 10 of the automobile is stopped. In this state, for example, when a person sitting in the driver's seat steps on the accelerator, the throttle opens. Then, the torque command value Ta corresponding to the throttle opening m is determined, and the drive circuit 7
4, the FET 71 is turned on and off at a predetermined frequency and a predetermined duty ratio, a current flows through the electromagnetic coil 39 of the torque transmission device 30, and the current also flows between the drain and source of the FET 71. For this reason, when the time passes with the accelerator depressed, there is a concern that the FET 71 may generate heat due to energization.

However, in the present embodiment, if the duty ratio continues to be equal to or more than the predetermined threshold value, the ECU 50 enters the sleep mode and the duty ratio is lowered after a predetermined time elapses. As a result, the current flowing between the drain and the source of the FET 71 also decreases, the load on the FET 71 decreases, and heat generation is suppressed.

As described above, according to the wheel driving force distribution control system 90 of the present embodiment, when the engine 10 is stopped, the current flowing through the FET 71 is lower than when the engine 10 is operating, and the heat generation amount of the FET 71 is suppressed. As a result, it is possible to suppress heat generation of the FET at low cost without increasing the specifications of the FET and adding new cooling means as in the conventional case.

<Second Embodiment> This embodiment is shown in FIG. 7, and is different from the first embodiment only in the configuration of the output program. Hereinafter, steps different from those in the first embodiment will be described, and steps having the same content will be denoted by the same step numbers and redundant description will be omitted. That is, in the output program K2 of the present embodiment, as shown in the figure, when the engine 10 is stopped (No in S11), the average current flowing through the electromagnetic coil 39 becomes equal to or higher than the predetermined threshold value. Check whether or not (S
16). Then, in a state where the average current flowing through the electromagnetic coil 39 is equal to or higher than the threshold value (Yes in S16), the predetermined time T
If the time has passed (Yes in S13), the electromagnetic coil 3
The current flowing through 9 is reduced (S17). Even with such a configuration, the same operational effect as that of the first embodiment can be obtained.

<Third Embodiment> This embodiment is shown in FIG. 8 and is different from the first embodiment only in the structure of the output program. As shown in the figure, in the output program K3 of the present embodiment, when the engine 10 is operating (Yes in S11), normal output control is performed (S15) while the engine 10 is stopped. If so (No in S11), the current command value I of the current passed through the electromagnetic coil 39 is held at 0 (S18). That is, FET
Hold 71 off. As a result, the engine 10
In this stopped state, heat generation of the FET 71 can be prevented and the driving sound of the FET 71 can be suppressed.

<Fourth Embodiment> The present embodiment is shown in FIG. 9, and is different from the first embodiment only in the configuration of the output program. As shown in the figure, in the output program K4 of the present embodiment, first, four wheels (front and rear wheels 14,
It is checked whether or not the vehicle speed (rotational speed) of 14, 15, 15) is 0 (S41). Then, when the vehicle speed is not 0 (No in S41), that is, when the automobile is moving, it is determined that the engine is not stopped, and normal output control is performed (S15).

On the other hand, when the vehicle speed is 0 (Yes in S41), it is checked whether or not the throttle opening m is equal to or more than a predetermined threshold value (S42). When the throttle opening m is smaller than the threshold value (No in S42), normal output control is performed (S15). When the throttle opening m is equal to or larger than the threshold value (Yes in S42), it is checked whether the predetermined time T has elapsed (S13). Here, even if the throttle opening m is equal to or more than the threshold value, when the predetermined time T has not elapsed (No in S13), normal output control is performed (S15). On the other hand, when the throttle opening m is equal to or greater than the threshold value and the predetermined time T has elapsed (S1
3), the frequency of the pulse voltage applied to the electromagnetic coil 39 is lowered.

As described above, according to this embodiment, it is possible to determine whether or not the engine is stopped by the vehicle speed, the throttle opening m, and the timer without taking in the signal from the tachometer 62 to the ECU 50. By lowering the frequency of the pulse voltage, the frequency of on / off of the FET 71 is reduced, and the amount of heat generation is suppressed.

<Other Embodiments> The present invention is not limited to the above-described embodiments. For example, the embodiments described below are also included in the technical scope of the present invention.
The present invention can be implemented by making various changes other than the following without departing from the scope of the invention. (1) In each of the above-described embodiments, the front wheel 14 is the "always-driving wheel" according to the present invention and the rear wheel 15 is the "wheel other than the always-driving wheel" according to the present invention. Good.

(2) In each of the above embodiments, the FET 71 is used as the switching element, but the switching element may be an element other than the FET.

(3) In each of the above embodiments, the electromagnetic coil 39 is used as the connection strength control unit, but the connection strength control unit may be a motor other than the electromagnetic coil.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a drive system of an automobile according to a first embodiment of the present invention.

FIG. 2 is a side sectional view showing the basic configuration of the torque transmission device.

FIG. 3 is a sectional view of a V-shaped recess.

FIG. 4 is a block diagram showing a configuration of an ECU.

FIG. 5: Flow chart of the main program

FIG. 6 is a flowchart of an output program.

FIG. 7 is a flowchart of an output program according to the second embodiment.

FIG. 8 is a flowchart of an output program according to the third embodiment.

FIG. 9 is a flowchart of an output program of the fourth embodiment.

[Explanation of symbols]

14 ... Front wheels (continuously driven wheels) 15 ... rear wheels (wheels other than constantly driven wheels) 30 ... Torque transmission device (torque transmission means) 31 ... Input section 32 ... Output unit 39 ... Electromagnetic coil (connection strength control unit) 50 ... ECU (transmission torque control means) 60 ... Throttle sensor (throttle opening detection means) 61 ... Rotational speed sensor (vehicle speed detecting means) 90 ... Wheel driving force distribution control system m ... Throttle opening Tp ... Pre-torque (first torque command value) Tn ... Rotational difference torque (second torque command value)

Continued front page    (72) Inventor Kiyonari Kato             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. F term (reference) 3D036 GA16 GB03 GD08 GE05 GG24                       GG37 GG40 GH09 GJ17

Claims (7)

[Claims] 1. A connection strength between an input section and an output section, the input section rotating in conjunction with a constantly driving wheel of an automobile, and an output section rotating in association with a wheel other than the constantly driving wheel. , A torque transmission means capable of changing the transmission torque from the input section to the output section by changing the current input to the connection strength control section, and a pulse voltage of a predetermined cycle is generated by driving the switching element. However, the transmission torque control means for controlling the transmission torque of the torque transmission means by the duty ratio of the pulse voltage, and the engine stop determination means for determining whether the engine of the vehicle is stopped, The transmission torque control means, based on the determination result of the engine stop determination means, when the engine is stopped, the coupling strength control is performed as compared with when the engine is operating. A wheel driving force distribution control system, characterized by being in a rest mode in which a current input to the control unit is reduced. 2. The wheel driving force distribution control system according to claim 1, wherein the transmission torque control means holds the current input to the coupling strength control unit at 0 in the rest mode. 3. A connecting strength between the input section and the output section, the input section rotating in conjunction with the constantly driving wheels of an automobile and the output section rotating in association with wheels other than the constantly driving wheels. , A torque transmission means capable of changing the transmission torque from the input section to the output section by changing the current input to the connection strength control section, and a pulse voltage of a predetermined cycle is generated by driving the switching element. However, the transmission torque control means for controlling the transmission torque of the torque transmission means by the duty ratio of the pulse voltage, and the engine stop determination means for determining whether the engine of the vehicle is stopped, The transmission torque control means, based on the determination result of the engine stop determination means, when the engine is stopped, the pulse voltage is higher than that when the engine is operating. The wheel driving force distribution control system is characterized in that it enters a rest mode in which the frequency of the wheel is lowered. 4. The transmission torque control means is in the sleep mode only when a predetermined time has elapsed in a state where the duty ratio is larger than a predetermined threshold value. A wheel driving force distribution control system according to item 1. 5. The transmission torque control means is in the rest mode only when a predetermined time has elapsed in a state where the average current input to the coupling strength control section is larger than a predetermined threshold value. The wheel driving force distribution control system according to any one of claims 1 to 3. 6. The engine stop determination means includes a vehicle speed detection means for detecting a vehicle speed of the vehicle, a throttle opening degree detection means for detecting a throttle opening degree of the vehicle, and a timer. The wheel according to any one of claims 1 to 3, wherein the engine is determined to be stopped when a predetermined time has elapsed while the throttle opening is 0 and the throttle opening is equal to or greater than a predetermined threshold value. Driving force distribution control system. 7. The wheel drive according to claim 1, wherein the engine stop determination means detects the engine speed to determine whether the engine is stopped. Power distribution control system.