JP2007131194A - Drive force distribution device for four-wheel drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To retain large transmission torque at a friction clutch even if a motor current is cut off without using a large-sized and heavy motor of continuous rating with high cost. <P>SOLUTION: This drive force distribution device for a four-wheel drive vehicle is provided with a conversion mechanism 11 for converting rotation motion to linear motion by hydraulic driving by the motor 38 to press the friction clutch 16 and a torque control unit 35 controls the transmission torque of the friction clutch 16 according to the drive force of the motor 38. A reverse prevention mechanism suppresses the rotation of the motor 38 relative to an opposite input from the conversion mechanism 11 side and the drive force from the motor 38 side is transmitted to the conversion mechanism 11. For example, the reverse prevention mechanism is constituted of a selective brake mechanism freely rotated in the normal rotation direction of the motor 38 and an operating braking force in a reverse rotation direction. A braking force required for suppressing reverse rotation from the conversion mechanism 11 is made to act in a motor stopping state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a driving force distribution device for a four-wheel drive vehicle that performs a distribution control of driving force to a front wheel or a rear wheel with a friction clutch capable of slipping.

  2. Description of the Related Art Conventionally, various four-wheel drive vehicle driving force distribution devices have been proposed in which a rotational torque of a motor is converted into a linear motion and a transmission torque is controlled by pressing a friction clutch according to the driving force of the motor.

  FIG. 13 shows a conventional driving force distribution device for a four-wheel drive vehicle. A conversion mechanism 204a for converting the rotational motion of the motor 202 into linear motion drives the hydraulic pump 206 by the motor 202 to generate hydraulic pressure. Is supplied to the cylinder 208 to move the piston 210 in the axial direction, and the friction clutch 200 is pressed by the pressure member 211 to control the transmission torque.

  The hydraulic pressure generated by the hydraulic pump 206 is detected by the pressure sensor 214, and the motor 202 is PWM-controlled so that the torque control unit (TFCU) 212 becomes the command hydraulic pressure determined based on the vehicle state.

  FIG. 14 shows another example of a conventional driving force distribution device for a four-wheel drive vehicle, in which a ball cam mechanism is used as a conversion mechanism 204b that converts the rotational motion of the motor 202 into linear motion. The conversion mechanism 204 b drives the gear 218 after decelerating the rotation of the motor 202 with the speed reducer 216, rotates the cam plate 220 with the gear 218, and cams through the ball 224 disposed between the fixed cam plate 222. The plate 220 is moved in the axial direction, and the friction clutch 200 is pressed by the pressure plate 232 via the thrust bearing 230 to control the driving torque.

  The ball 224 is disposed between the cam grooves 226 and 228 formed on the relative surfaces of the cam plates 220 and 222. When the cam plate 220 rotates in the arrow A direction with respect to the fixed cam plate 222, the ball 224 moves. Then, the cam plate 220 is moved in the direction of arrow B.

  The pressing load of the conversion mechanism 204b due to the rotation of the motor 202 is estimated by a load estimation sensor 234 that estimates the load by detecting the rotation angle of the motor 202 so that the torque control unit 212 becomes a pressing load command value. 202 is PWM controlled.

  FIG. 15 shows an example of a conventional driving force distribution device for a four-wheel drive vehicle in which the distribution control of the driving force to the front wheels is controlled by a friction clutch using the ball cam mechanism shown in FIG. (Patent Document 1).

  15 and 16, an input shaft 242 that is driven from the engine via a transmission is provided in the case 241. The input shaft 242 is directly connected to the first output shaft 243 of the rear wheel, and the second output of the front wheel. The shaft 244 is connected via a friction clutch 250, a sprocket gear 256, a chain 257, and a sprocket gear 258. The fastening force of the friction clutch 250 is continuously controlled by driving the motor 262, and controls the driving force distribution of the front and rear wheels of the vehicle.

  The motor 262 opens the relative distance between the two ball cams facing each other, that is, by rotating the support ring 269 and the pressure ring 270 with the ball 271 interposed between the cam inclined grooves on the opposing surfaces, and the friction clutch. The pressing force of 250 is controlled.

That is, as shown in FIG. 16, the pressure ring 270 which is disposed so as to be rotatable with respect to the support ring 269 sleeve 268 and is opposed to the ball 271 has the pin 272 formed on the outer periphery inserted into the axial groove 273 of the case. When the rotation is restricted and the rotation of the motor 262 is decelerated and transmitted to the support ring 269 with which the gear 265 is engaged, the pressure ring 270 with the restricted rotation is rotated by the cam inclined groove with respect to the ball 271 so that the ball cams The relative distance changes and moves in the axial direction to control the pressing force of the friction clutch 250.
Japanese Patent No. 2715340 US Patent Publication 2003/0029690

  However, what is common to the mechanism of such a conventional driving force distribution device for a four-wheel drive vehicle is that it is necessary to keep current flowing through the motor in order to maintain the transmission torque of the friction clutch. Therefore, a motor with a large continuous rating is required, and there is a problem that the system is large, heavy, and expensive.

  In order to solve this problem, there is a motor that is always connected to the motor so that torque can be maintained without applying current to the motor. However, the electromagnetic brake has a large space and costs. There was also a problem. In addition, since it takes time to release the electromagnetic brake by passing an electric current, there is a problem that the torque of the friction clutch cannot be controlled quickly.

It is an object of the present invention to provide a driving force distribution device for a four-wheel drive vehicle that can maintain a large transmission torque in a friction clutch even when the motor current is cut off without using a large, heavy, and costly continuous rated motor. And

  The present invention includes a friction clutch, a motor, a conversion mechanism that converts the rotational motion of the motor into linear motion and presses the friction clutch, and a controller that controls the driving force of the motor. Provided is a driving force distribution device for a four-wheel drive vehicle that controls transmission torque of a clutch.

  With respect to such a drive power distribution device for a four-wheel drive vehicle, the present invention provides a reverse rotation prevention mechanism that prevents rotation against reverse input from the conversion mechanism side and transmits drive force from the motor side to the conversion mechanism. It is provided.

  Here, the reverse rotation prevention mechanism is configured by a selective brake mechanism that freely rotates in the forward rotation direction of the motor and brake force in the reverse rotation direction, and prevents reverse rotation from the conversion mechanism when the motor is stopped. It is characterized by the necessary braking force.

The brake type reverse rotation prevention function
A one-way clutch that fixes the inner race to the motor drive shaft, freely rotates the inner race with the outer race in the forward rotation direction, and locks the inner race with the outer race in the reverse rotation direction;
A brake mechanism for applying a predetermined braking force to the outer race of the one-way clutch;
Is provided.

  In another form of the brake type reverse rotation prevention mechanism, a worm gear speed reducer is provided between the conversion mechanism and the motor so that a reaction force from the conversion mechanism acts in the axial direction of the motor, and an inner race is provided on the motor shaft. The motor is equipped with a one-way clutch that freely rotates the inner race with the outer race in the forward rotation direction and locks the inner race with the outer race in the reverse rotation direction. A brake mechanism for applying a braking force to the outer race of the one-way clutch in response to the acting axial reaction force is provided.

In other forms of the brake type reverse rotation prevention mechanism,
Inner race using motor drive shaft,
An outer race fixed to the case and having an inner race rotatably provided in the shaft hole;
A shoe storage portion that extends in a radial direction from the shaft hole of the outer race, and that has an inclined surface that is higher in the forward rotation direction of the drive shaft and lower in the reverse rotation direction at the peripheral end;
A brake shoe housed in the shoe storage part, forming an arcuate surface in sliding contact with the inner race on the inner periphery, and forming an inclined surface in sliding contact with the inclined surface of the shoe storage part on the outer periphery;
A spring for urging the brake shoe in a direction in which the inclined surface of the shoe storage portion is lowered;
The brake shoe is moved in the direction in which the inclined surface becomes higher with respect to the forward rotation direction, and the inner race of the drive shaft rotates freely with respect to the outer race, and the brake shoe is in the direction in which the inclined surface becomes lower in the reverse rotation direction To stop the inner race of the drive shaft against the outer race.

  The conversion mechanism is composed of a hydraulic pump driven by a motor and a piston that receives the hydraulic pressure discharged from the hydraulic pump and presses the friction clutch, and after driving the motor to raise the hydraulic pressure to the first threshold value When the motor is stopped and the hydraulic pressure drops to the second threshold value, the intermittent operation is performed every time the motor is driven again, thereby controlling the hydraulic pressure within the range of the first threshold value and the second threshold value.

The reverse rotation prevention mechanism
A lock mechanism that separates the motor output shaft and the drive shaft that drives the conversion mechanism, and locks the conversion mechanism drive shaft when the motor is stopped;
It is composed of means for releasing the lock mechanism when driving the motor and transmitting the driving force from the motor output shaft to the conversion mechanism driving shaft.
When the motor is driven, the conversion mechanism is driven, and when the motor is stopped, the conversion mechanism is locked.

  According to the present invention, without using a large, heavy, and costly continuous rated motor, the motor current is turned off in a state where the rotational motion of the motor is converted into a linear motion and the friction clutch is pressed to generate the transmission torque. However, the reverse rotation prevention mechanism prevents the reverse rotation due to the reaction force from the friction clutch, and can maintain a large transmission torque in the friction clutch.

  In addition, since it is not necessary to keep the current flowing to maintain the torque, the current capacity of the controller can be reduced, and the controller can be made smaller and cheaper.

Further, the energy for driving the motor can be saved as a vehicle. Further, a method of always applying an electromagnetic brake so that the motor does not reverse is conceivable. However, since the driving torque is smaller than that in that case, the motor can be reduced.

  FIG. 1 is a cross-sectional view showing an embodiment of a driving force distribution device for a four-wheel drive vehicle according to the present invention. As a conversion mechanism, a rotary motion is converted into a linear motion by a hydraulic drive by a motor to control transmission torque of a friction clutch. It is characterized by doing.

  In FIG. 1, the driving force distribution device for a four-wheel drive vehicle of the present invention has a case 10, and an input shaft 12 for inputting rotation from the engine via an automatic transmission or a manual transmission is provided on the left side of the case 10. The input shaft 12 is directly connected to the rear wheel output shaft 14 disposed coaxially.

  A friction clutch 16 is provided coaxially with the rear wheel output shaft 14. The friction clutch 16 has a clutch hub 44 fixed to the rear wheel output shaft 14, and a clutch drum 46 is connected to a sprocket gear 50 that is rotatably provided to the rear wheel output shaft 14. In parallel with the rear wheel output shaft 14, a front wheel output shaft 20 for extracting power to the opposite side is provided in the case 10, and a sprocket gear 52 is integrally formed on the front wheel output shaft 20, and the friction clutch 16 side. The chain belt 18 is connected to and connected to the sprocket gear 50.

  In such a four-wheel drive vehicle driving force distribution device, the clutch hub 44 and the clutch drum 46 of the friction clutch 16 are disconnected during two-wheel drive, and the rotation of the input shaft 12 is directly applied to the rear wheel output shaft 14. Communicated. During four-wheel drive, the friction clutch 16 is in a connected state, and rotation from the input shaft 12 is transmitted to the front wheel output shaft via the rear wheel output shaft 14, the friction clutch 16, the sprocket gear 50, the chain belt 18, and the sprocket gear 52. 20 is also transmitted.

  For the friction clutch 16, a conversion mechanism for controlling the clutch fastening force of the multi-plate clutch 48 provided between the clutch hub 44 and the clutch drum 46 is provided. In this conversion mechanism, the hydraulic pump 62 is driven by the motor 38, and high pressure oil from the hydraulic pump 62 is supplied to a piston 64 slidably provided in a cylinder 63 disposed on the right side of the friction clutch 16, and the piston 64 is moved to the left side. The multi-plate clutch 48 is pushed by the pressing member 42 through the thrust bearing 56, the clutch fastening force is increased, and the transmission torque is controlled.

  In contrast to such a conversion mechanism that controls clutch transmission torque, the present invention further includes a reverse rotation prevention mechanism 60 between the motor 38 and the hydraulic pump 62. The reverse rotation prevention mechanism 60 transmits the rotation as it is to the hydraulic pump 62 (conversion mechanism side) in response to the driving force from the motor 38, and against the reverse rotation driving force from the hydraulic pump 62 side (conversion mechanism side). Prevents rotation.

  In this embodiment, the reverse rotation prevention mechanism 60 uses a brake type reverse rotation prevention mechanism, and includes a one-way clutch 78 and a brake shoe 80.

  A torque control unit (TFCU) 35 is provided for the motor 38, and the engagement force of the friction clutch 16 is increased by driving the motor 38 in the forward direction by the output signal E1 of the torque control unit 35, and the motor 38 is reversely rotated. By driving, the fastening force of the friction clutch 16 is released.

  The torque control unit 35 further receives a hydraulic pressure detection signal E2 of the hydraulic pump 62 detected by the pressure sensor 61. Therefore, the torque control unit 35 performs feedback control using the detected hydraulic pressure signal E2 of the pressure sensor 61 so that the predetermined hydraulic pressure corresponding to the fastening force of the friction clutch 16 set as the control target is obtained. The torque control unit 35 controls the engagement force of the friction clutch 16 by controlling the motor 38 in accordance with switching from 2WD to 4WD or switching settings of high and low transmission torque in the state of switching to 4WD. become.

  FIG. 2 is an explanatory view of a conversion mechanism according to the present invention for controlling the torque transmitted by the friction clutch by converting the rotary motion into a linear motion by hydraulic drive by the motor used in the embodiment of FIG.

  In FIG. 2, the conversion mechanism 11 drives the hydraulic pump 62 by the motor 38, applies the hydraulic pressure generated by the hydraulic pump 62 to the piston 64 slidably provided with respect to the cylinder 63 in the conversion mechanism 11, and moves the piston 64 to the left. By pushing the pressing member 42 through the thrust bearing 56, the engagement force of the multi-plate clutch 48 provided between the clutch hub 44 and the clutch drum 46 in the friction clutch 16 is increased, and the clutch transmission torque is increased. I have control.

  With regard to such a conversion mechanism 11, the present invention further includes a reverse rotation prevention mechanism 60 between the motor 38 and the hydraulic pump 62. The hydraulic pressure applied to the piston 64 by the hydraulic pump 62 is detected by the pressure sensor 61 and input to the torque control unit 35 as a hydraulic pressure detection signal E2.

  FIG. 3 is an explanatory diagram of the first embodiment of the reverse rotation prevention mechanism 60 used in the present invention. The first embodiment is characterized by a brake-type reverse rotation prevention mechanism.

  FIG. 3A is a schematic configuration of a brake type reverse rotation prevention mechanism 60A. A one-way clutch 78 is provided on the motor output shaft 39 for driving the hydraulic pump 62 of the motor 38, and the brake shoe is pressed against the one-way clutch 78 by a spring 82. 80 is provided. The one-way clutch 78 includes an inner race 78a fixed to the motor output shaft 39, and an outer race 78b provided to the inner race 78a so as to be rotatable in one direction via a roller 78c.

  FIG. 3B is an explanatory diagram viewed from the axial direction of the brake type reverse rotation preventing mechanism 60A. The brake shoe 80 is brought into contact with the outer race 78b located on the outer periphery of the one-way clutch 78 by the spring 82, thereby increasing the braking force. Is added.

  FIG. 4 is an explanatory diagram of the one-way clutch 78 used in the brake-type reverse rotation prevention mechanism 60A shown in FIGS. The one-way clutch 78 is formed integrally with an inner race 78a fixed to the motor output shaft 39, an outer race 78b that is rotatably arranged in one direction via a roller 78c on the outer side of the inner race 78a, and an outer race 78b. It comprises a plurality of rollers 78c that are held and arranged by a roller holding portion 78d.

  The surface of the outer race 78b with which the roller 78c abuts forms an inclined cam surface 78e. The cam surface 78e rotates counterclockwise as indicated by arrow A of the inner race 78a that rotates integrally with the motor output shaft 39 when the outer race 78b that is braked and stopped by the brake shoe 80 (see FIG. 3) is fixed. Is free, and the clockwise rotation indicated by the broken-line arrow B is locked.

  Referring again to FIG. 3, by providing such a brake type reverse rotation prevention mechanism 60 </ b> A between the motor 38 and the hydraulic pump 62, the motor output shaft 39 of the motor 38 increases the fastening force of the friction clutch 16. When the motor rotates forward in the direction in which the clutch is pressed, the rotation is free, and the reverse rotation is applied with the reaction force from the friction clutch when the motor 38 is stopped when the specified pressing force (clutch engagement force) is obtained for the friction clutch. At times, the brake shoe 80 is pressed against the outer race 78b by the spring 82 to apply the brake, so that the brake acts against the reverse rotation from the hydraulic pump 62 to prevent reverse rotation.

  In the brake type reverse rotation prevention mechanism 60A shown in FIGS. 3A and 3B, it is necessary to overcome the reaction force of the friction clutch 16 and rotate the motor 38 at the time of forward rotation to increase the transmission torque of the friction clutch. Need. FIG. 3C is a characteristic graph showing the relationship of the pressing force F in the friction clutch 16 with respect to the motor rotational displacement θ of the motor 38 in an ideal state where there is no internal leakage of the hydraulic pump, and the friction according to the motor rotational displacement θ. The pressing force F of the clutch 16 increases in a substantially linear manner.

  The characteristic diagram of FIG. 3C shows an example in which the set rotational displacements of the motor rotational displacement are set in two stages of θ1 and θ2, and the pressing force of the friction clutch 16 corresponding to these set rotational displacements θ1 and θ2. F1 and F2 are obtained. The set rotational displacements θ1 and θ2 of the two-stage motor 38 correspond to the high and low switching of the transmission torque in the 4WD switching state in the friction clutch 16.

  As shown in FIG. 3C, when the clutch engagement force is controlled by applying the pressing force F2 to the friction clutch 16 by controlling the rotational displacement of the motor 38 to, for example, the set rotational displacement θ2, the set value is reached. The current of the motor 38 is cut off, and the reaction force from the friction clutch 16 side acts in the direction of reversing the motor 38 with the interruption of the current of the motor 38.

If the reaction force from the friction clutch side is larger than the friction of the entire mechanism, the motor 38 is reversed and the transmission torque in the friction clutch 16 cannot be maintained. Therefore, in the present invention, the brake type reverse rotation prevention mechanism 60A is provided, and the braking force is applied to the reaction force from the friction clutch side to prevent the reverse rotation of the motor 38 and the transmission torque of the friction clutch 16 is maintained. The braking force for preventing this reverse rotation may be as strong as the following formula.

(Brake force)> {(reaction force from friction clutch)-(mechanism friction)} (1)

On the other hand, at the time of reverse rotation in which the transmission torque is reduced after holding the transmission torque by pressing the friction clutch 16, it is necessary to overcome the brake force of the brake type reverse rotation prevention mechanism 60A and reverse the motor 38. Since the force acts in the reverse direction, a larger driving force of the motor 38 is not required. The motor driving force at the time of reverse rotation when lowering the transmission torque is given by the following relational expression.

(Motor driving force)>
{(Brake force) + (Mechanism friction)-(Reaction force from friction clutch)} (2)

  FIG. 5 is a time chart of motor control for holding the pressing force of the friction clutch in the hydraulic drive of FIG. In the conversion mechanism 11 using the hydraulic pump 62 of FIG. 2, the motor 38 is operated in a state where a predetermined clutch transmission torque is generated in the friction clutch 16 by the hydraulic pressure generated by driving the hydraulic pump 62 by the normal rotation of the motor 38. Even if the motor is stopped and reverse rotation due to the reaction force from the friction clutch 16 is blocked by the braking action of the brake type reverse rotation prevention mechanism 60A, the pressing force to the friction clutch 16 gradually decreases due to internal leakage of the hydraulic pump 62.

  In FIG. 5, the hydraulic pump 62 is driven by the forward rotation of the motor 38 to increase the hydraulic pressure, and the transmission torque of the friction clutch 16 is increased to the set torque T1 by pressing by the piston 64, and when the set torque T1 is reached. When the forward rotation of the motor 38 is stopped, the transmission torque gradually decreases with the passage of time as the internal leakage of the hydraulic pump 62 occurs.

  Therefore, a lower set torque T2 is set with respect to the set torque T1, and when the transmitted torque is reduced to the set torque T2, the motor 38 is rotated forward again to restore the transmitted torque to T1, and control is repeated.

  In the on / off driving of the motor 38 for holding the transmission torque T1, since the off cycle that is stopped with respect to the on cycle is sufficiently long, a current for holding the transmission torque T1 is continuously supplied to the motor 38. The power consumption of the motor 38 can be sufficiently reduced as compared with the case where the motor 38 is provided, and the heat generation of the motor 38 can be suppressed to the minimum necessary.

  In the detection of the transmission torques T1 and T2 in FIG. 5, since there is a certain relationship between the hydraulic pressure applied to the piston 64 by the hydraulic pump 62 and the transmission torque due to the pressing force of the friction clutch 16, the pressure sensor 61 is actually used. Detects the hydraulic pressure generated by the hydraulic pump 62 and compares it with the set pressures P1 and P2 corresponding to the set torques T1 and T2 of the transfer torque, thereby turning on and off the motor 38 for holding the transfer torque at the set torque T1. Control becomes possible.

  FIG. 6 is an explanatory view of a second embodiment of the reverse rotation prevention mechanism used in the present invention, and is characterized in that a brake type reverse rotation prevention mechanism is formed as in FIG. In FIG. 6, the brake type reverse rotation preventing mechanism 60B includes an inner race 84 using the motor output shaft 39 of the motor 38, an outer race 86 fixed to the case side and provided with an inner race 84 rotatably provided in the shaft hole, and an outer race 86. The shoe housing part 88 is provided at three positions by opening the shaft hole, the brake shoe 90 housed in the shoe housing part 88, and a spring 92 for pressing the brake shoe.

  The shoe storage portion 88 formed in the shaft hole of the outer race 86 forms a storage portion in the radial direction from the shaft hole, and becomes higher in the forward rotation direction indicated by the arrow A of the inner race 84 and lower in the reverse rotation direction at the outer end. An inclined surface 88a is formed. The brake shoe 90 housed in the shoe housing part 88 forms an arcuate surface that is in contact with the inner race 84 on the inner periphery, and an inclined surface that is in contact with the inclined surface 88a of the shoe storage part 88 on the outer periphery.

  In such a brake type reverse rotation prevention mechanism 60B, when the motor 38 rotates the motor output shaft 39, that is, the inner race 84, in the direction of arrow A by the motor 38, the brake shoe 90 is The spring 92 is pressed in the direction in which the gap is widened by the gradient of the inclined surface 88a, and the inner race 84 can be freely rotated with respect to the outer race 86 on the fixed side.

  On the other hand, the inner race 84 rotates counterclockwise at the time of reverse rotation that receives a reaction force from the friction clutch 16 side, and the brake shoe 90 moves along the downward direction of the inclined surface 88a of the shoe storage portion 88 along with this. The brakes 90 move together with the pressing, and the brake force is applied to the inner race 84 by the brake shoe 90, so that the reverse rotation of the inner race 84 can be prevented.

  In this case, the braking force for preventing the reverse rotation with respect to the reaction force applied to the friction clutch 16 when the current of the motor 38 is cut off may be the same condition as the above-described equation (1) shown in FIG. The motor driving force for overcoming the braking force at the time of reverse rotation for lowering the transmission torque of the clutch 16 to reverse the motor 38 may also be the condition of the above-described equation (2) shown in FIG.

  FIG. 7 is an explanatory view of a third embodiment of the reverse rotation prevention mechanism used in the present invention. Like FIG. 3, a brake type reverse rotation prevention mechanism is used.

  In FIG. 7, the motor 38 includes a stator 96 and a rotor 98, the stator 96 is fixed inside the motor case 94, the stator 96 is fixed to the motor rotation shaft 39, and the motor rotation shaft 39 faces the case 10 on the left side. The bearing 104 is rotatably supported, and the left side is rotatably supported on the end side of the motor case 94 by a bearing 106.

  A worm 100 is formed on the left side of the motor rotating shaft 39, and a worm gear 102 having a rotating shaft orthogonal to the worm gear is engaged with each other to constitute a worm gear mechanism. When the worm gear 102 receives a reaction force in the direction of arrow A from the friction clutch device side, the worm gear mechanism transmits the reaction force indicated by the arrow B in the axial direction of the motor rotation shaft 39 when rotating the worm 100.

  A brake-type reverse rotation prevention mechanism 60 </ b> C is provided at the right end of the motor rotation shaft 39. The brake-type reverse rotation prevention mechanism 60 </ b> C includes a one-way clutch 108, and an inner race 110 is fixed to the shaft end of the motor drive shaft 28, and an outer race 112 is incorporated in the end portion of the motor case 94. The outer race 112 is not fixed in the motor 94, and can rotate if a rotational force exceeding the braking force is applied.

  The one-way clutch 108 freely rotates the inner race 110 with the outer race 112 with respect to the normal rotation of the motor rotation shaft 39, and locks the inner race 110 with the outer race 112 with respect to the reverse rotation direction. Receives axial reaction force.

  The inner end surface of the motor case is formed as a friction surface 114 relative to the side end of the outer race 112 of the one-way clutch 108, and generates a braking force when the outer race 112 is pressed by receiving an axial reaction force. Prevent reversal.

  In this case, the braking force for preventing the reverse rotation with respect to the reaction force applied to the friction surface 114 when the current of the motor 38 is interrupted may be the same as the above-described equation (1) shown in FIG. The motor driving force for overcoming the braking force at the time of reverse rotation for lowering the transmission torque of the clutch 16 to reverse the motor 38 may also be the condition of the above-described equation (2) shown in FIG.

  FIG. 8 is a cross-sectional view showing another embodiment of the driving force distribution device for a four-wheel drive vehicle according to the present invention. It is characterized by controlling.

  In FIG. 8, the driving force distribution device for a four-wheel drive vehicle of the present invention has a case 10, and an input shaft 12 for inputting rotation from the engine via an automatic transmission or a manual transmission is provided on the left side of the case 10. The input shaft 12 is directly connected to the rear wheel output shaft 14 disposed coaxially.

  A friction clutch 16 is provided coaxially with the rear wheel output shaft 14. The friction clutch 16 has a clutch hub 44 fixed to the rear wheel output shaft 14, and a clutch drum 46 is connected to a sprocket gear 50 that is rotatably provided to the rear wheel output shaft 14. In parallel with the rear wheel output shaft 14, a front wheel output shaft 20 for extracting power to the opposite side is provided in the case 10, and a sprocket gear 52 is integrally formed on the front wheel output shaft 20, and the friction clutch 16 side. The chain belt 18 is connected to and connected to the sprocket gear 50.

  In such a four-wheel drive vehicle driving force distribution device, the clutch hub 44 and the clutch drum 46 of the friction clutch 16 are disconnected during two-wheel drive, and the rotation of the input shaft 12 is directly applied to the rear wheel output shaft 14. Communicated. During four-wheel drive, the friction clutch 16 is in a connected state, and rotation from the input shaft 12 is transmitted to the front wheel output shaft via the rear wheel output shaft 14, the friction clutch 16, the sprocket gear 50, the chain belt 18, and the sprocket gear 52. 20 is also transmitted.

  For the friction clutch 16, a conversion mechanism for controlling the clutch fastening force of the multi-plate clutch 48 provided between the clutch hub 44 and the clutch drum 46 is provided. This conversion mechanism includes an arm from a ball 26 and a ball cam 22 that are sandwiched and held by one inclined groove portion of the opposing cam surfaces of a pair of ball cams 22 and 24 provided coaxially with the rear wheel output shaft 14 so as to be relatively rotatable. An external gear 30 that is extended by a portion and formed on the front end side, and an arm portion that extends from the ball cam 24 and is formed at a position of a spatially overlapping rotating surface facing the external gear 30 inside the front end side. The tooth gear 34, the drive gear 36 that is arranged between the external gear 30 and the internal gear 34 and meshes with both, the motor 38 that rotationally drives the drive gear 36 via the speed reducer 40, and the ball cams 22 and 24 are arranged on both sides. Thrust bearings 54, 56, a fixed member 58 disposed outside the thrust bearing 54 and fixed to the rear wheel output shaft 14, and a rear wheel output shaft disposed on the thrust bearing 56 side. Member 42 pressing movable in the axial and rotational directions relative to 4, further comprised of an anti-reverse mechanism 60 for controlling the motor 38.

  FIG. 9 shows the conversion mechanism of the friction clutch 16 shown in FIG. In FIG. 9, a pair of ball cams 22, 24 are rotatably provided on the rear wheel output shaft 14, and a plurality of balls 26 are held between a plurality of inclined grooves provided on one of the relative surfaces of the ball cams 22, 24. Has been. In the ball cam mechanism composed of the ball cams 22 and 24 and the ball 26, the relative distance between the ball cams 22 and 24 changes the axial distance between the two depending on the depth of the inclined groove portion where the ball 26 is located.

  An arm portion 28 extends from the ball cam 22, and an external gear 30 is formed in an L-shaped portion formed upward at the tip of the arm portion 28. Further, an internal gear 34 is formed opposite to the external gear 30 inside an L-shaped portion formed downward at the tip of the arm portion 32 extending from the ball cam 24. For this reason, the external gear 30 and the internal gear 34 are located on the same gear rotation surface with respect to the rotation center, and have a structure sharing the rotation surface.

  A drive gear 36 is disposed between the external gear 30 and the internal gear 34 so as to mesh with both, and the drive gear 36 is connected to an output shaft of a speed reducer 40 that decelerates and outputs the rotation of the motor 38. Here, when the speed reducer 40 is rotated in the direction of arrow A by the motor, the external gear 30 meshed with the drive gear 36 rotates in the direction of arrow B, and at the same time, the internal gear 34 rotates in the direction of arrow C. The relative rotation of the ball cams 22 and 24 accompanying the rotation of the tooth gear 30 and the internal gear 34 in the opposite directions changes the interval between the ball cam 22 and the ball cam 24.

  Here, in the mechanism of the present invention for controlling the clutch fastening force, the external gear 30 and the internal gear 34 integrally formed at the tips of the arm portions 28 and 32 extending from the pair of ball cams 22 and 24 are provided. Due to the spatially overlapping structure, the space inside the device is shared, the installation space in the device can be reduced, and the driving force distribution device for a four-wheel drive vehicle can be reduced in size and weight.

  Referring to FIG. 8 again, a reverse rotation prevention mechanism 60 is disposed between the motor 38 that drives the conversion mechanism using the ball cam mechanism and the speed reducer 40. The reverse rotation prevention mechanism 60 prevents rotation with respect to the reverse input from the conversion mechanism side, and transmits rotation to the conversion mechanism as it is with respect to the driving force from the motor 38 side.

  FIG. 10 is an explanatory diagram of a conversion mechanism according to the present invention that presses the friction clutch by converting rotational motion into linear motion by direct drive by the motor shown in FIG. In FIG. 10, the conversion mechanism 11 decelerates the rotational force of the motor 38 by the speed reducer 40, applies it to the drive gear 36, converts it into linear motion by the ball cam mechanism shown in FIG. 9, and presses the friction clutch 16. .

  A ball 26 is disposed between the ball cams 22 and 24 in the ball cam mechanism, and as shown on the right side, cam grooves 22a and 24a are formed on the relative surfaces of the ball cams 22 and 24, and the cam grooves 22a and 24a For example, when the ball cam 24 rotates relative to the ball cam 22 in the direction of arrow A, the ball 26 moves on the cam grooves 22a and 24a, and the ball cam 24 moves in the direction of arrow B. Then, the friction clutch 16 is pressed.

  A reverse rotation prevention mechanism 60 is arranged between the motor 38 and the speed reducer 40 in the conversion mechanism 11, and the forward rotation for pressing the friction clutch 16 of the motor 38 is transmitted to the speed reducer 40 as it is, and the current of the motor 38 is reduced. The reverse rotation applied via the speed reducer 40 is prevented by the reaction force of the friction clutch 16 when shut off. As the reverse rotation prevention mechanism 60, any of the brake type reverse rotation prevention mechanism 60A in FIG. 3, the brake type reverse rotation prevention mechanism 60B in FIG. 6, or the brake type reverse rotation prevention mechanism 60C in FIG. 7 may be used.

  The motor 38 is controlled to rotate forward or reversely by an output signal E1 from the torque control unit 35. Further, the pressing load applied to the friction clutch 16 is detected by the load estimation sensor 41 based on the drive current of the motor 38 and is input to the torque control unit 35 as the load estimation signal E3. By driving the motor 38 by feedback control using the load estimation signal E3 from the load estimation sensor 41, the pressing load on the friction clutch 16 can be controlled to a set load for obtaining a predetermined transmission torque.

  FIG. 11 is an explanatory view of a fourth embodiment of the reverse rotation preventing mechanism used in the present invention. The fourth embodiment is characterized in that a lock type reverse rotation prevention mechanism that mechanically prevents reverse rotation with respect to the brake type shown in FIGS. 3, 6, and 7 is used.

  FIG. 11A is a cross-sectional view of the lock-type reverse rotation prevention mechanism as the fourth embodiment of the reverse rotation prevention mechanism cut in the radial direction, and FIG. 11B is a cross-sectional view cut in the axial direction. Show.

  11A, the lock type reverse rotation prevention mechanism 60D includes an input member 68 fixed to the input shaft 65, an output member 70 fixed to the output shaft 66, a lock ring 72 fixed to the case, and an inner side of the lock ring 72. The roller holder 74 is arranged with a predetermined friction, and the roller 76 is rotatably held by the roller holder 74 and is arranged with respect to the output member 70 through a predetermined gap at a neutral position shown in the drawing. .

  The output member 70 is formed with three radiating arm portions 70a in the outer peripheral direction from the center portion where the output shaft 66 is mounted, and a linear cam surface 70b in a direction perpendicular to the radiating axis is formed at the tip of the radiating arm portion 70a. The roller holder 74 is rotatably held on the inner diameter portion of the lock ring 72 with a slight friction, and has a shape extending radially with respect to the radiation arm portion 70a of the output member 70 through a predetermined gap. The part 74a is formed in the inner peripheral part.

  Each roller 76 is rotatably supported at the center of the overhanging portion 74a of the roller retainer 74, and the inner end of the roller 76 is formed at a neutral position shown in the figure from a straight surface facing the straight cam surface 70b of the overhanging portion 74a. A predetermined gap is formed between the output member 70 and the straight cam surface 70b.

  The input member 68 has claw portions 68a arranged in three spaces partitioned by the radiation arm portion 70a of the output member 70 and the protruding portion 74a of the roller retainer 74. The claw portion 68a is shown in FIG. As shown in the cross section, a radial shape having a radial length from the radiation arm portion 70a of the output member 70 to the overhanging portion 74a of the roller retainer 74 is provided.

  FIG. 12 is an explanatory diagram of operations during forward rotation and reverse rotation according to the fourth embodiment of FIG. FIG. 12 shows the reverse rotation prevention operation when the output member 70 is reversely rotated in the direction of the arrow in response to the reaction force from the friction clutch 16 side.

  When a driving force in the reverse rotation direction is applied to the output member 70 by the reaction force from the friction clutch side, there is a slight friction between the lock ring 72 and the roller retainer 74, so that the output member 70 moves against the roller 76. It rotates in the direction of the arrow ahead.

  As a result, the neutral relationship between the roller 76 and the output member 70 is lost, and there is no gap between the roller 76 and the linear cam surface 70b of the output member 70. The roller 76 is opposite to the rotation direction of the linear cam surface 70b of the output member 70. The cam surface comes into contact and is locked. At this time, the input member 68 may be slightly rotated by the output member 70, but the input member 68 also stops at the position where the output member 70 is locked. This prevents reverse rotation due to the reaction force of the friction clutch 16 applied from the output shaft 66, and prevents reverse rotation due to the reaction force from being applied to the motor even when the current of the motor 38 is turned off.

  FIG. 12B shows the operation when the motor 38 is rotated forward. When the input member 68 is driven in the direction of the arrow by the rotation of the motor 38, the side surface on the rotation side of the claw portion 68 a of the input member 68 is the side surface of the radiation arm portion 70 a of the input member 68 and the overhanging portion 74 a of the roller retainer 74. In this case, both are aligned at the neutral position, and the driving force from the input member 68 is directly transmitted to the output member 70 while the roller 76 and the output member 70 are held at the neutral position.

  In this case, a gap is formed between the output member 70 and the roller 76, and the roller 76 is idled in the lock ring 72 integrally with the roller holder 74 and is not locked.

  11 and 12 can also be used for the reverse rotation prevention mechanism 60 in the conversion mechanism 11 shown in FIG. 2 or the reverse rotation prevention mechanism 60 provided in the conversion mechanism 11 in FIG. .

  Here, the brake type reverse rotation prevention mechanism 60A, 60B, 60C shown in FIGS. 3, 6 and 7 and the reverse rotation prevention mechanism 60D shown in FIGS. In the reverse rotation prevention mechanism 60D, there is a slight backlash from the neutral position to the locking or free rotation in both the reverse rotation of FIG. 12A and the forward rotation of FIG. 12B. Therefore, the lock type reverse rotation prevention mechanism 60D is suitable when only switching between 2WD and 4WD is performed.

  In contrast, the brake type reverse rotation prevention mechanisms 60A, 60B, 60C have almost no backlash when locked from the neutral position by reverse rotation and free rotation by forward rotation. It is suitable for the case of changing in steps or continuously.

The present invention includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited by the numerical values shown in the above embodiments.

Sectional drawing which showed embodiment of the driving force distribution apparatus for four-wheel drive vehicles by this invention Explanatory drawing of the conversion mechanism by this invention which converts a rotational motion into a linear motion and presses a friction clutch by the hydraulic drive by a motor Explanatory drawing of 1st Embodiment of the reverse rotation prevention mechanism used by this invention Explanatory drawing of the one-way clutch of FIG. FIG. 2 is a time chart of motor control for holding the pressing force of the friction clutch in the hydraulic drive of FIG. Explanatory drawing of 2nd Embodiment of the reverse rotation prevention mechanism used by this invention Explanatory drawing of 3rd Embodiment of the reverse rotation prevention mechanism used by this invention Sectional drawing which showed other embodiment of the driving force distribution apparatus for four-wheel drive vehicles by this invention Explanatory drawing of the conversion mechanism of FIG. Explanatory drawing of the conversion mechanism by this invention which converts a rotational motion into a linear motion by the direct drive by a motor, and presses a friction clutch Explanatory drawing of 4th Embodiment of the reverse rotation prevention mechanism used by this invention Explanatory drawing of the operation | movement at the time of forward rotation and reverse rotation by 4th Embodiment of FIG. Explanatory drawing of a conventional conversion mechanism that converts rotational motion into linear motion and presses the friction clutch by direct drive by a motor Explanatory drawing of a conventional conversion mechanism that converts a rotary motion into a linear motion and presses the friction clutch by hydraulic drive by a motor Sectional drawing of the conventional driving force distribution apparatus for four-wheel drive vehicles provided with the conversion mechanism of FIG. Explanatory drawing which took out and showed the conversion mechanism which controls the fastening force of the friction clutch of FIG.

Explanation of symbols

10: Case 11: Conversion mechanism 12: Input shaft 14: Rear wheel output shaft 16: Friction clutch 18: Chain belt 20: Front wheel output shaft 22, 24: Ball cam 26: Ball 28, 32: Arm portion 30: External gear 34 : Internal gear 35: Torque control unit (TFCU)
36: drive gear 38: motor 39: motor output shaft 40: speed reducer 41: load estimation sensor 42: pressing member 44: clutch hub 46: clutch drum 48: multi-plate clutch 50, 52: sprocket gears 54, 56: thrust Bearing 58: Fixed member 60: Reverse rotation prevention mechanism 60A, 60B: Brake type reverse rotation prevention mechanism 60C: Lock type reverse rotation prevention mechanism 61: Pressure sensor 62: Hydraulic pump 63: Cylinder 64: Piston 65: Input shaft 66: Output shaft 68: Input member 68a: Claw portion 70: Output member 70a: Radiating arm portion 70b: Linear cam surface 72: Lock ring 74: Roller retainer 74a: Overhang portion 76: Roller 78, 108: One-way clutch 78a, 84, 110: Inner Race 78b, 86, 112: Outer race 78c: Roller 78d: Roller Holding portion 78e: cam surface 80, 90: brake shoe 82, 92: spring 88: shoe storage portion 94: motor case 94a: motor case end 96: stator 98: rotor 100: worm 102: worm gear 104, 106: bearing 114 : Friction surface

Claims (7)

Friction clutch,
A motor,
A conversion mechanism for converting the rotational motion of the motor into a linear motion and pressing the friction clutch;
A controller for controlling the driving force of the motor;
A drive force distribution device for a four-wheel drive vehicle that controls transmission torque of the friction clutch according to the drive force of the motor,
Driving force distribution for a four-wheel drive vehicle provided with a reverse rotation preventing mechanism that prevents rotation against reverse input from the conversion mechanism side and transmits driving force from the motor side to the conversion mechanism apparatus.
2. The drive force distribution device for a four-wheel drive vehicle according to claim 1, wherein the reverse rotation prevention mechanism rotates freely in a forward rotation direction of the motor and a brake force acts in the reverse rotation direction. A driving force distribution device for a four-wheel drive vehicle, characterized in that a braking force necessary to prevent reverse rotation from the conversion mechanism works when the motor is stopped.
The drive force distribution device for a four-wheel drive vehicle according to claim 2, wherein the reverse rotation prevention mechanism includes:
A one-way clutch that fixes an inner race to a motor drive shaft, freely rotates the inner race with an outer race in the forward rotation direction, and locks the inner race with an outer race in a reverse rotation direction;
A brake mechanism for applying a predetermined braking force to the outer race of the one-way clutch;
A driving force distribution device for a four-wheel drive vehicle.
The driving force distribution device for a four-wheel drive vehicle according to claim 2,
A worm gear reducer is provided between the conversion mechanism and the motor so that a reaction force from the conversion mechanism acts in the axial direction of the motor, and an inner race is fixed on the motor shaft, and A one-way clutch that freely rotates the inner race with the outer race and locks the inner race with the outer race in the reverse rotation direction, and receives the axial reaction force acting on the motor to receive the one-way clutch A driving force distribution device for a four-wheel drive vehicle, comprising a brake mechanism for applying a brake force to an outer race of the vehicle.
The drive force distribution device for a four-wheel drive vehicle according to claim 2, wherein the reverse rotation prevention mechanism includes:
Inner race using motor drive shaft,
An outer race fixed to the case and rotatably provided with the inner race in the shaft hole;
A shoe storage portion that extends in a radial direction from the shaft hole of the outer race, and that has an inclined surface that is high in the forward rotation direction of the drive shaft and lower in the reverse rotation direction at the peripheral end;
A brake shoe housed in the shoe housing portion, forming an arc surface in sliding contact with the inner race on the inner periphery, and forming an inclined surface sliding in contact with the inclined surface of the shoe storage portion on the outer periphery;
A spring for urging the brake shoe in a direction in which the inclined surface of the shoe storage portion is lowered; and moving the brake shoe in a direction in which the inclined surface is increased with respect to the forward rotation direction to disengage the inner race of the drive shaft. Driving force distribution device for a four-wheel drive vehicle that rotates freely with respect to the race and moves the brake shoe in a direction with a lower inclined surface in the reverse rotation direction to stop the inner race of the drive shaft against the outer race. .
In the driving force distribution device for a four-wheel drive vehicle according to claim 1,
The conversion mechanism includes a hydraulic pump driven by the motor and a piston that receives the hydraulic pressure discharged from the hydraulic pump and presses the friction clutch, and drives the motor to increase the hydraulic pressure to the first threshold value. After stopping the motor, the hydraulic pressure is controlled within the range of the first threshold value and the second threshold value by performing intermittent operation every time the motor is driven again when the hydraulic pressure drops to the second threshold value. Characteristic driving force distribution device for four-wheel drive vehicles
In the driving force distribution device for a four-wheel drive vehicle according to claim 1,
The reverse rotation prevention mechanism separates a motor output shaft and a drive shaft that drives the conversion mechanism, and a lock mechanism that locks the conversion mechanism drive shaft when the motor is stopped;
When the motor is driven, the lock mechanism is released and the driving force from the motor output shaft is transmitted to the conversion mechanism drive shaft.
A driving force distribution device for a four-wheel drive vehicle, wherein the conversion mechanism is driven when the motor is driven, and the conversion mechanism is locked when the motor is stopped.

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