JP2010007750A - Hydraulic power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic power transmission device having, in addition to a function of torque distribution between right and left wheels or front and rear wheels, a function of automatically setting a differential lock state when a rotation speed difference between the right and left wheels or the front and rear wheels exceeds a predetermined value. <P>SOLUTION: The hydraulic power transmission device is provided with a housing formed with a pair of cam surfaces, a pair of rotors formed with a plurality of piston chambers 128, a plurality of pistons driven by the cam surfaces during differential rotation, a rotary valve caught between opposed end surfaces of the pair of rotors to be rotatably in slide contact with them and formed in opposite faces with a plurality of intake ports and discharge ports, a high pressure chamber formed in the rotary valve, a shutoff valve providing an orifice between the high pressure chamber and a low pressure chamber in the housing, transmitting torque according to the rotation speed difference and shutting off the orifice when pressure of the high pressure chamber exceeds a predetermined value and a relief valve opening the high pressure chamber when the pressure further rises and exceeds a predetermined value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a hydraulic power transmission device that uses a pair of hydraulic power transmission joints and distributes torque according to a difference in rotational speed between front and rear wheels and left and right wheels.

  In a conventional differential device having a torque-sensitive differential limiting mechanism, as a mechanical device, a multi-plate clutch method, a helical gear method, a torque sensor method, a cam as disclosed in, for example, JP-A-2000-205375 The method is known.

  The multi-plate clutch system is composed of a differential case, a pinion, a pair of side gears and a multi-plate clutch arranged between the side gear and the differential case, and the driving force input to the differential case is differentially (differential case and side gear via the pinion). Alternatively, it is transmitted to both side gears while absorbing the difference in rotational speed between the side gears. Further, during differential operation, the differential limiting force is obtained by the side gear pressing the multi-plate clutch by the thrust load generated by the meshing reaction force between the pinion and the side gear.

  The helical gear system includes a differential case, a pinion made of a helical gear, and a pair of side gears, and the driving force input to the differential case is transmitted to both side gears while absorbing the differential via the pinion. Further, the pinion and the side gear are pressed against the differential case by the thrust load generated by the meshing reaction force between the pinion and the side gear during the differential operation, and the differential limiting force is obtained by the friction force.

  The Torsen system consists of a differential case, a plurality of pairs of element gears consisting of a combination of worm gears and spur gears, and a pair of side gears consisting of worm gears.The driving force input to the differential case absorbs the differential while absorbing the differential through the element gears. It is transmitted to the side gear. In addition, the side gear is pressed against the differential case by the thrust load generated by the meshing reaction force between the element gear and the side gear during the differential operation, and the differential limiting force is obtained by the friction force.

  The cam system includes a differential case, a cam follower, and a pair of face cams, and the driving force input to the differential case is transmitted to both face cams while absorbing the differential via the cam follower. Further, the differential limiting force is obtained by the frictional force generated between the cam follower and the face cam generated during the differential operation.

  As a conventional differential device having a torque-sensitive differential limiting mechanism, a twin coupling type power transmission device is proposed in Japanese Patent Application Laid-Open No. 5-44744, for example. This twin coupling type power transmission device is composed of a differential case and a pair of hydraulic couplings, and the hydraulic coupling is disposed between a rotor and a rotor provided with a cam and a plurality of plungers formed on the inner surface of the differential case. It is comprised with the rotary valve which has the orifice made.

  The driving force input to the differential case generates a torque corresponding to the rotational speed difference in the rotor that is differential with respect to the differential case. For example, in an FR (front engine-rear drive) -based four-wheel drive vehicle in which this power transmission device is disposed between the left and right front wheels, if the left and right rear wheels slip on a low μ road surface, the space between the rear wheels and the front wheels A difference in rotational speed is generated between the two couplings with respect to the differential case, and torque corresponding to the difference in rotational speed is generated and transmitted to the left and right front wheels.

Also, if the left front wheel loses grip on the low μ road surface at the same time as the left and right rear wheels slip, only the coupling on the right front wheel side that does not slip with respect to the differential case will differentially generate torque according to the rotational speed difference. To the right front wheel. That is, with this type of power transmission device, it is possible to perform torque distribution between the front and rear wheels and the left and right wheels.
JP 2000-205375 A Japanese Patent Laid-Open No. 5-44744

  However, in such a conventional differential device with a mechanical differential limiting mechanism, only the differential absorption function (differential function) and the differential limiting function (limited slip differential function) between the left and right wheels can be used in any method. In the case of switching the driving force between the front and rear wheels and performing the diff lock, there is a problem that another switching mechanism using a lever or an actuator has to be added.

  In addition, such a conventional hydraulic power transmission device has a differential absorption function and a differential limiting function not only between the left and right wheels but also between the front and rear wheels. It was necessary to add another switching mechanism by levers and actuators.

The present invention has been made in view of such problems. In addition to the torque distribution function between the left and right wheels and between the front and rear wheels, the rotational speed difference between the left and right wheels or between the front and rear wheels has exceeded a predetermined value. It is an object of the present invention to provide a hydraulic power transmission device having a function of automatically making a differential lock state sometimes.

  In order to achieve this object, the present invention is configured as follows. First, the present invention provides a housing that is provided between three shafts that can rotate relative to each other, is connected to a first shaft, and has a pair of cam surfaces having two or more cam ridges on both inner surfaces, a second shaft, A pair of rotors that are coupled to the third shaft and that are rotatably accommodated in the housing and formed in the axial direction with the plurality of piston chambers facing the cam surface, and each of the plurality of piston chambers A plurality of pistons that are received by the return spring to be reciprocally moved and that are driven by the cam surface during relative rotation between the first shaft and the second shaft or between the first shaft and the third shaft; Plural sandwiched between the opposing end surfaces of the pair of rotors so as to be slidably rotatable and positioned so as to be rotatable at a predetermined angle with the housing, and acting as a suction valve and a discharge valve depending on the positional relationship with the cam crest Inhalation port, It is formed between one valve body having outlet ports formed on both sides, a high pressure chamber formed by communicating all discharge ports of the valve body, a high pressure chamber, a housing inner wall, a valve body, a rotor, and a piston. An object of the present invention is to provide a hydraulic power transmission device in which an orifice is provided between a low-pressure chamber formed of a space and transmits torque according to a rotational speed difference between the first shaft, the second shaft, and / or the third shaft. To do.

  The present invention is characterized in that in such a hydraulic power transmission device, there is provided a closing valve for closing the orifice when the pressure in the high pressure chamber exceeds a predetermined value.

In addition, a relief valve is provided for opening the high pressure chamber when the pressure in the high pressure chamber exceeds a predetermined value.

  According to the present invention, by providing a shut-off valve that closes the orifice when the pressure in the high pressure chamber exceeds a predetermined value, the differential lock state is automatically set when the rotational speed difference between the left and right wheels and between the front and rear wheels increases. It is possible to improve the rough road running performance as compared with a conventional power transmission device with only differential restriction.

In addition, by providing a relief valve that opens the high-pressure chamber when the pressure in the high-pressure chamber exceeds a specified value, the device can be damaged by limiting the load by suppressing the occurrence of abnormal high torque in the diff lock state. Can be prevented.

  FIG. 1 is an explanatory diagram showing a case where a hydraulic power transmission device according to the present invention is applied to an FR-based four-wheel drive vehicle. In FIG. 1, a hydraulic power transmission device 10 according to this embodiment is provided in a four-wheel drive vehicle 12, and includes a left front wheel axle shaft 32, a right front wheel axle shaft 34 (second or third shaft), and a front wheel propeller shaft 30 ( It is arranged between three axes (first axis).

  The driving force from the engine 14 is shifted by the transmission 16 and transmitted to the rear wheel differential device 20 and the hydraulic power transmission device 10 through the rear wheel propeller shaft 18 and the front wheel propeller shaft 30, respectively. The driving force transmitted to the rear wheel differential device 20 drives the left rear wheel 26 and the right rear wheel 28 via the left rear wheel axle shaft 22 and the right rear wheel axle shaft 24, respectively, to the hydraulic power transmission device 10. The transmitted driving force drives the left front wheel 36 and the right front wheel 38 via the left front wheel axle shaft 32 and the right front wheel axle shaft 34, respectively.

  FIG. 2 is an explanatory view showing a case where the hydraulic power transmission device according to the present invention is applied to an FF (front engine-front drive) based four-wheel drive vehicle. In FIG. 2, a hydraulic power transmission device 40 is provided in a four-wheel drive vehicle 42, and includes a left rear wheel axle shaft 60, a right rear wheel axle shaft 62 (second or third axis), and a propeller shaft 58 (first axis). ) Between the three axes.

  The driving force from the engine 44 is shifted by the transmission 46 and transmitted to the hydraulic power transmission device 40 via the front wheel differential 48 and the propeller shaft 58. The driving force transmitted to the front wheel differential device 48 drives the left front wheel 54 and the right front wheel 56 via the left front wheel axle shaft 50 and the right front wheel axle shaft 52, respectively, and is transmitted to the hydraulic power transmission device 40. The force drives the left rear wheel 64 and the right rear wheel 66 through the left rear wheel axle shaft 60 and the right rear wheel axle shaft 62, respectively.

  FIG. 3 is a cross-sectional view showing an embodiment of the hydraulic power transmission device according to the present invention, which is applied to the FR-based four-wheel drive vehicle of FIG. In FIG. 3, the hydraulic power transmission device 10 houses a differential case 102, a ring gear 104, and a drive pinion 106 in a main body case 100.

  A differential case 102 in which oil is enclosed and a pair of left and right hydraulic couplings is incorporated is fixed integrally with the ring gear 104 by a bolt 108 (housing), and is rotatably supported by the body case 100 by ball bearings 110 and 112. The In addition, the ring gear 104 may be integrally formed with the differential case 102 to form a housing.

  The drive pinion 106 that meshes with the ring gear 104 is rotatably supported by the ball bearing 114 and the roller bearing 116 with respect to the main body case 100, and the connecting hole 106a that opens to the lower outer side of the main body case 100 of the drive pinion 106 has a universal joint. It is connected to the front wheel propeller shaft 30 via.

  4 is an enlarged cross-sectional view of the differential case 102, the ring gear 104, and the inside of the hydraulic power transmission device 10 of FIG. In FIG. 4, a cam 118 having a cam surface 118 a is fixed to the inner side surface of the differential case 102 by a set screw 120, and a cam surface 104 a is formed on the inner side surface of the ring gear 104 on the right side facing the cam 118. The

  The cam surface 118a and the cam surface 104a are arranged so that two or more peaks and valleys face each other, and the inner side of the cam surface 118a and the cam surface 104a is coaxial with the differential case 102 and the ring gear 104 and is rotatable. Incorporated.

  The left rotor 122 and the right rotor 124 are formed with piston chambers 126 and 128 that are opened outward. The pistons 130 and 132 are slidably accommodated in the piston chambers 126 and 128, and the central portions of the left rotor 122 and the right rotor 124. Are provided with connecting holes 122a and 124a for connecting the left front wheel axle shaft 32 and the right front wheel axle shaft 34 by splines, respectively.

  Balls 134 and 136 are interposed between the pistons 130 and 132 and the cam surfaces 118a and 104a so that the left rotor 122 and the right rotor 124 can smoothly rotate relative to the cam surfaces 118a and 104a. In addition, return springs 138 and 140 are incorporated in the piston chambers 126 and 128, and the pistons 130 and 132 are pressed against the cam surfaces 118a and 104a via the balls 134 and 136, respectively.

  Here, if four cam crests are formed on the cam surfaces 118a and 104a, the sum of the crests and troughs is 8. Therefore, there are seven pistons 130 and 132 to be driven in the rotors 122 and 124, respectively. Although it is possible to reduce the pulsation of torque transmission by installing an odd number such as nine, the number of cam ridges and the number of pistons can be determined as needed.

  In FIG. 4, for convenience of explanation, the upper part has a cam surface 118a, 104a in a mountain state and the pistons 130, 132 have a discharge stroke, and the lower part has a cam surface 118a, 104a in a valley state, and the piston 130, 132 has a suction stroke. In other words, the inside of the differential case 102 and the ring gear 104 is not shown in a single plane.

  A plurality of suction and discharge holes 142 and 144 are formed in the left rotor 122 and the right rotor 124 so as to communicate with the piston chambers 126 and 128, respectively, and slidably contact with each other between the opposing end surfaces of the left rotor 122 and the right rotor 124. One rotary valve 146 (valve element) is provided.

  5A and 5B are explanatory views showing the rotary valve 146. FIG. 5A is a cross-sectional view, FIG. 5B is an end surface, as viewed from the axial direction of the differential case 102 shown in FIG. It is.

  4 and 5A, the rotary valve 146 includes a common suction port 148 and a common discharge port 150 that can communicate with the suction and discharge holes 142 and 144 of the left rotor 122 and the right rotor 124, respectively. A plurality of 146 are formed penetrating between both end faces of 146. In this embodiment, the cam surfaces 118a and 104a have four cam crests, and four suction ports 148 and four discharge ports 150 are formed.

  Inside the rotary valve 146, a suction path 152 is formed on the outer peripheral surface from each suction port 148, and a communication path 154 is formed on the inner peripheral surface. The suction path 152 includes the inner wall of the differential case 102, the rotary valve 146, and the left and right rotors 122, 124. The suction port 148 communicates with the low-pressure chamber 156 formed of a space formed between the pistons 130 and 132 and the balls 134 and 136.

  The communication path 154 communicates with the accumulator chamber 158 provided in the center of the rotary valve 146 and the suction port 148. The accumulator 158 chamber is formed by an accumulator piston 160 and a spring 162, and the accumulator piston 160 moves in accordance with the volume change accompanying the temperature change of the enclosed oil to change the volume of the accumulator chamber 158, and the low pressure side (low pressure chamber 156 In addition, the pressure in the accumulator chamber 158) can always be maintained at the spring adjustment pressure.

  In FIG. 4 and FIG. 5 (B), in order to keep the pressure of each suction port 148 (low pressure side) and the pressure of each discharge port 150 (high pressure side) constant at both end faces of the rotary valve 146, A communication groove 164 that communicates with the port 148 and a communication groove 166 that communicates with each discharge port 150 are formed. Further, a suction groove 168 communicates from the communication groove 164 to the outer peripheral surface of the rotary valve 146, and the suction port 148 and the low pressure chamber 156 are communicated with each other.

  In FIG. 5A, an orifice (flow resistance generating means) communicating with the low pressure chamber 156 through a communication hole 170 at one portion (lower side) of the discharge port 150 provided in the rotary valve 146, and the high pressure chamber An auto-lock mechanism 174 is provided that includes a shut-off valve that closes the orifice and puts the diff-locked state when the pressure exceeds a predetermined value.

  In addition, when the pressure in the high pressure chamber further rises and exceeds a predetermined value via the communication hole 172 to the other part (upper side) of the discharge port 150, the high pressure chamber and the low pressure chamber are communicated abnormally. A torque limiter mechanism 176 composed of a relief valve that suppresses generation of a high torque is provided.

  4 and 5, the rotary valve 146 constitutes a timing member that determines the opening and closing timing of the suction and discharge holes 142 and 144, and when the pistons 130 and 132 are in the suction stroke, the rotary valve 146 has a suction port 148. The suction and discharge holes 142 and 144 of the left rotor 122 and the right rotor 124 are in communication with each other, and oil is supplied from the low pressure chamber 156 to the piston chambers 126 and 128 through the suction path 152, the suction groove 168, the suction port 148, and the suction and discharge holes 142 and 144. Can be inhaled.

  When the pistons 130 and 132 are in the discharge stroke, the relationship is opposite to the suction stroke, and the suction discharge holes 142 and 144 of the left rotor 122 and the right rotor 124 communicate with the communication groove 166 via the discharge port 150 of the rotary valve 146. .

  FIG. 6 is an explanatory diagram showing the positional relationship between the rotary valve 146 and the differential case 102, and shows a state in which the cross section of the differential case 102 and the end face of the rotary valve 146 are viewed from the axial direction of the differential case 102, for example, from the right direction.

  In FIG. 6, the protrusions 146 a and 146 b formed on the outer periphery of the rotary valve 146 engage with the positioning protrusions 102 a formed on the inner periphery of the differential case 102, thereby positioning that regulates the phase relationship between the differential case 102 and the rotary valve 146. The mechanism is configured.

  The differential rotation of the left rotor 122 and the right rotor 124 with respect to the differential case 102 causes the rotary valve 146 to rotate in the R direction as shown in FIG. 6A, and in the L direction as shown in FIG. 6B. In the case of rotation, the positional relationship between the peaks and valleys of the cam surfaces 118a and 104a and the suction port 148 and the discharge port 150 is shifted by a half phase at the maximum.

  For example, when the left rotor 122 and the right rotor 124 are differentially rotated in the R direction and the rotary valve 146 is restricted to the position shown in FIG. 6A, the position of the discharge port 150 is the discharge stroke of the pistons 130 and 132. Which coincides with the climbing slope from the bottom of the cam surfaces 118a, 104a to the summit.

  When the cam surfaces 118a and 104a are in this state and the left rotor 122 and the right rotor 124 are differentially rotated in the L direction, the pistons 130 and 132 move downhill from the top of the cam surfaces 118a and 104a to the bottom of the valley. As shown in FIG. 6B, the rotary valve 146 is also regulated by being rotated by a half phase in the L direction, so that the suction port 150 in FIG. Port 148 is coming, and oil can be sucked from suction port 148.

  7A and 7B are cross-sectional views showing details and operation of the auto-lock mechanism 174 in FIG. 5A, FIG. 7A in the unlocked state, and FIG. 7B in the locked state. It is an AA arrow directional view.

  In FIG. 7A, a storage hole 178 communicating with the communication hole 170 is formed at one location of the discharge port 150 provided in the rotary valve 146, and a material harder than the rotary valve 146 is formed in the storage hole 178. The collar member 180 is accommodated. The collar member 180 is fixed by screws with a plug 182.

  The collar member 180 is formed with a high-pressure chamber 186 in which the ball 184 is movably accommodated. The high-pressure chamber 186 communicates with the communication hole 170 through the upper opening 180a and through the right opening 180b. The communication hole 188 communicates. The communication hole 188 communicates with the storage hole 190, and the needle member 192 is slidably stored in the storage hole 190.

  The needle member 192 includes a small-diameter needle portion 192a, a large-diameter guide portion 192b, and a stopper portion 192c, and the position of the ball 184 is controlled by the needle member 192. A spring 196 is inserted between the large-diameter guide portion 192b and a plug 194 that is screwed to the side opposite to the communication hole 188 of the storage hole 190, and the gap between the needle portion 192a and the opening portion 180b is a flow resistance. The orifice 198 is used as a generating means.

  When the ball 184 is held by the needle member 192, the orifice 198 is open. However, when the holding of the ball 184 is released and becomes free, the ball 184 is formed in the valve seat formed in the opening 180b of the collar member 180. It becomes possible to close the orifice 198 by sitting on 180c.

  The needle member 192 housed in the housing hole 190 is urged by the spring 196 to hold the ball 184 on the left wall surface of the housing hole 178 and in this state flows from the discharge port 150 into the high pressure chamber 186 through the communication hole 170. The oil generates a flow resistance at the orifice 198, is decompressed, and is discharged from the drain hole 200 to the low pressure chamber 156.

  When the differential rotation (transmission torque) of the left rotor 122 and the right rotor 124 with respect to the differential case 102 increases and the hydraulic pressure in the high pressure chamber 186 that houses the ball 184 rises to a predetermined value or more, as shown in FIG. The needle member 192 moves to the right against the bias of the spring 196 and releases the holding of the ball 184.

  When the ball 184 becomes free from the holding of the needle member 192, the ball 184 is seated on the valve seat 180c by the flow of oil from the opening 180a to the opening 180b, and closes the opening 180b (orifice 198). The stopper portion 192c abuts against the plug 194, thereby preventing the needle member 192 from moving beyond a predetermined distance.

  The hydraulic pressure (transmission torque) at the time of unlocking is determined by the biasing force of the spring 196 with respect to the product of the contact area of the valve seat 180c and the ball 184 and the internal pressure, so the contact area is changed by the inclination angle of the contact surface of the valve seat 180c. In order to prevent hunting, it can be released after the pressure is slightly lower than the hydraulic pressure at the time of locking.

  FIG. 8 is a cross-sectional view showing details and operation of the torque limiter mechanism 176 of FIG. 5, FIG. 8A is in a non-operating state, FIG. 8B is in an operating state, and B in FIG. FIG.

  In FIG. 8A, a storage hole 202 communicating with the communication hole 172 is formed at one location of the discharge port 150 provided in the rotary valve 146, and the storage hole 202 is made of a material harder than the rotary valve 146. The collar member 204 is stored. The collar member 204 is fixed by screws with a plug 206.

  A high pressure chamber 208 is formed in the collar member 204. The high pressure chamber 208 communicates with the communication hole 172 via the lower opening 204a, and communicates with the communication hole 210 via the left opening 204b. Yes. The communication hole 210 communicates with the storage hole 212, and the retainer 214 is slidably stored in the storage hole 212.

  The retainer 214 has a large-diameter guide portion 214b having a concave portion 214a formed at the tip and a small-diameter stopper portion 214c. A ball 216 is formed on the end surface of the storage hole 212 on the communication hole 210 side by the concave portion 214a of the retainer 214. It is seated and held on the valve seat 212a. A spring 218 is interposed between the large-diameter guide portion 214b and a plug 220 that is screwed to the side opposite to the communication hole 210 of the storage hole 212.

  When the ball 216 is held on the valve seat 212 a by the retainer 214, the communication hole 210 is closed. However, when the holding of the ball 216 is released, the ball 216 moves between the recess 214 a of the retainer 214 and the storage hole 212. It can move freely between the valve seat 212a.

  In a normal state, the retainer 214 housed in the housing hole 212 is urged by the spring 218 to hold the ball 216 on the valve seat 212a, and flows into the high pressure chamber 208 from the discharge port 150 through the communication hole 172 in this state. The oil is not discharged from the drain hole 222 to the low pressure chamber 156 because the communication hole 210 is closed by the ball 216.

  Depending on the traveling state of the four-wheel drive vehicle 12, the auto-lock mechanism 174 may be activated to lock the differential between the left rotor 122, the right rotor 124, and the differential case 102, and thus a higher torque may be generated.

  In such a case, when the hydraulic pressure in the high pressure chamber 208 rises to a predetermined value or more and exceeds the urging force of the spring 218, the ball 216 and the retainer 214 resist the spring 218 as shown in FIG. Move to the left and release the ball 216.

  The ball 216 is free from restraint on the valve seat 212a, but is held by being pressed against the recess 214a by the flow of oil from the communication hole 210, and the oil from the communication hole 210 enters the low pressure chamber 156 from the drain hole 222. It is discharged and suppresses an increase in hydraulic pressure in the high pressure chamber 208. The stopper 214c abuts against the plug 220, thereby preventing the retainer 214 from moving beyond a predetermined distance.

  By suppressing the hydraulic pressure in the high pressure chamber 208 to a predetermined value, generation of excessive torque is suppressed, and the load applied to the left rotor 212 and the right rotor 214 and the left front wheel axle shaft 32 and the right front wheel axle shaft 34 respectively connected thereto is limited. In addition, the apparatus can be prevented from being destroyed.

  In the present embodiment, the storage holes 178, 190, 202, 212 and the plugs 182, 194, 206, 220 of the auto-lock mechanism 174 and the torque limiter mechanism 176 are made common, and for that purpose, the torque limiter mechanism 176 is used. Although the collar member 204 is also provided on the side, the collar member 204 may be omitted.

  FIG. 9 is an explanatory view showing the operation according to the differential rotation direction. FIG. 9A shows the case where the differential directions of the left rotor 122 and the right rotor 124 are the same, and FIG. 9B shows the left rotor 122. And the differential direction of the right rotor 124 is different.

  When there is no rotational speed difference between the differential case 102 and the left rotor 122 and the right rotor 124, the pistons 130 and 132 do not operate and torque is not transmitted, but as shown in FIG. When the same rotational speed difference in the rotational direction C is generated between the left rotor 122 and the right rotor 124, the pistons 130-1 and 132-1 in the discharge stroke are pushed in the arrow direction by the cam surfaces 118a and 104a.

  At this time, since the suction / discharge holes 142-1 and 144-1 communicate with the discharge port 150 of the rotary valve 146, the pistons 130-1 and 132-1 suck the oil in the piston chambers 126-1 and 128-1. It pushes out to the discharge port 150 from the discharge holes 142-1, 144-1. The oil pushed out to the discharge port 150 passes through the communication groove 166, the communication hole 170 and the orifice 198, and is supplied from the suction path 152 to the suction port 148 through the low pressure chamber 156.

  At this time, the oil flow resistance through the orifice 198 increases the hydraulic pressure in the high pressure chamber 186, the communication hole 170, the communication groove 166, the discharge port 150, and the piston chambers 126-1, 128-1, and the pistons 130-1, 132- 1 generates a reaction force.

  Against this reaction force, torque is generated by rotating the differential case 102 via the cam surfaces 118a and 104a, and torque is transmitted between the differential case 102, the left rotor 122, and the right rotor 124. In addition, since each discharge port 150 is connected by the communication groove | channel 166, the hydraulic pressure of all the piston chambers 126 and 128 in a discharge stroke becomes equal.

  Further, when the left rotor 122 and the right rotor 124 rotate with respect to the differential case 102, a suction stroke is started. The suction and discharge holes 142-2 and 144-2 communicate with the suction port 148, and the pistons 130-2 and 132-2 have return springs 138 and 138, respectively. The oil in the suction passage 152 is sucked into the piston chambers 126-2 and 128-2 through the suction port 148 and the suction / discharge holes 142-2 and 144-2, because the oil is pushed by 140 and returns along the cam surfaces 118a and 104a. Is done.

  The flow rate of the oil passing through the orifice 198 by this series of operations is the sum of the discharge amounts of the pistons 130 and 132 of the left rotor 122 and the right rotor 124, and all the discharge ports 150 connected to the communication groove 166 are used. Since the pressures are equal, when the differential directions of the left and right front wheels 36 and 38 with respect to the differential case 102 are the same, equal torque is transmitted to the left and right front wheels 36 and 38 according to the differential rotational speed.

  Therefore, during normal driving with low differential, the transmitted torque is small, so that the drive loss is small, and the occurrence of the tight corner braking phenomenon is also suppressed. Since the transmission torque is large at the time of high differential, the running performance on rough roads can be improved.

  When the differential rotation directions of the left rotor 122 and the right rotor 124 are opposite, for example, as shown in FIG. 9B, the rotation direction of the right rotor 124 is indicated by the direction D, and the right rotor 124 The suction and discharge timing is reversed from that of the left rotor 122, and the oil in the piston chamber 128-2 is discharged to the suction port 148, so that almost no torque is generated.

  Further, since the oil discharged from the piston chamber 126-1 is also sucked into the piston chamber 128-1 of the right rotor 124 via the discharge port 150, the flow rate of the oil passing through the orifice 198 is reduced. As a result, the transmission torque is reduced.

  Accordingly, during cornering of a paved road where the differential directions of the inner ring and the outer ring differ with respect to the differential case 102, the torque transmission action of the left rotor 122 and the right rotor 124 becomes weak, and the tight corner braking phenomenon hardly occurs.

  FIG. 10 is a graph showing the characteristics of the transmission torque with respect to the differential rotation speed, where the vertical axis represents the transmission torque T and the horizontal axis represents the differential rotation speed ΔN. In FIG. 10, the normal torque characteristic is indicated by E, T2 is the lock torque at which the auto-lock mechanism 174 operates, and N2 is the differential rotational speed at that time. The torque characteristic at the time of locking is indicated by G, and T3 is a limit torque at which the torque limiter mechanism 176 operates.

  When traveling on a rough road or the like, the hydraulic power transmission device 10 includes a differential case 102 that is driven by the front wheel propeller shaft 30 and a differential rotational speed of the left rotor 122 and the right rotor 124 that connect the left axle shaft 32 and the right axle shaft 34. Increases, the torque characteristic E is shown. When the differential rotational speed reaches N2, the pressure in the high pressure chamber 186 exceeds a predetermined value and the auto-lock mechanism 174 is activated. As shown by the torque characteristic F, the differential rotational speed is It decreases at a stretch to N1.

  Thereafter, the transmission torque increases, but changes with a torque characteristic G slightly inclined in the direction in which the differential rotation speed increases due to pressure leak of the auto-lock mechanism 174 or the like. When the transmission torque decreases, unlocking is performed with a torque T1 slightly lower than the torque T2, and the torque characteristic I returns to the normal torque characteristic E.

  When the torque characteristic G reaches the limit torque T3, the pressure in the high pressure chamber 208 exceeds a predetermined value, and the torque limiter mechanism 176 is operated to suppress the pressure increase and prevent the device from being destroyed. When the torque limiter mechanism 176 is operated, the left rotor 122 and the right rotor 124 are temporarily idled, and the differential rotational speed increases at a stretch as indicated by the torque characteristic H.

  The above embodiment is an example in which the hydraulic power transmission device of the present invention is provided on the front wheel side for an FR-based four-wheel drive vehicle as shown in FIG. 1, but as shown in FIG. The FF-based four-wheel drive vehicle can be applied in exactly the same manner by providing the hydraulic power transmission device of the present invention on the rear wheel side.

In addition, the present invention is not limited to the above-described embodiments, and includes appropriate modifications that do not impair the objects and advantages thereof.

Explanatory drawing which shows the case where the hydraulic power transmission device of the present invention is applied to an FR-based four-wheel drive vehicle Explanatory drawing which shows the case where the hydraulic power transmission device of the present invention is applied to an FF-based four-wheel drive vehicle Sectional drawing which shows one Embodiment of the hydraulic power transmission device by this invention FIG. 3 is an enlarged cross-sectional view of the differential case, the ring gear, and the inside thereof. Explanatory drawing showing a rotary valve Explanatory drawing showing the positional relationship between the rotary valve and differential case Sectional drawing which shows the detail and operation | movement of the auto-lock mechanism of FIG. Sectional drawing which shows the detail and operation | movement of the torque limiter mechanism of FIG. Explanatory diagram showing the effect of differential rotation direction Graph showing characteristics of transmission torque with respect to differential rotation speed

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 40: Hydraulic power transmission device 12, 42: Four-wheel drive vehicle 14, 44: Engine 16, 46: Transmission 18: Rear-wheel propeller shaft 20: Rear-wheel differential gear 22, 60: Left rear-wheel axle shaft 24, 62: Right rear wheel axle shaft 26, 64: Left rear wheel 28, 66: Right rear wheel 30: Front wheel propeller shaft 32, 50: Left front wheel axle shaft 34, 52: Right front wheel axle shaft 36, 54: Left front wheel 38, 56: Right front wheel 48: Front wheel differential 58: Propeller shaft 100: Main body case 102: Differential case 104: Ring gear 106: Drive pinion 108: Bolts 110, 112, 114: Ball bearing 116: Roller bearing 118: Cam 120 : Set screw 122: Left rotor 124: Right rotor 126 and 128: Piston chambers 130 and 132 Piston 134, 136: Ball 138, 140: Return spring 142, 144: Suction / discharge hole 146: Rotary valve 148: Suction port 150: Discharge port 152: Suction path 154: Communication path 156: Low pressure chamber 158: Accumulator chamber 160: Accumulator Piston 162: Spring 164, 166: Communication groove 168: Suction groove 170, 172, 188, 210: Communication hole 174: Auto lock mechanism 176: Torque limiter mechanism 178, 190, 202, 212: Storage hole 180, 204: Collar member 182, 194, 206, 220: Plug 184, 216: Ball 186, 208: High pressure chamber 192: Needle member 196, 218: Spring 198: Orifice 200, 222: Drain hole 214: Retainer

Claims (2)

A housing provided between three shafts that can rotate relative to each other, coupled to the first shaft, and having a pair of cam surfaces having two or more cam ridges on both inner surfaces;
A pair of rotors coupled to the second shaft and the third shaft and accommodated rotatably and opposed to each other in the housing, and having a plurality of piston chambers facing the cam surface and formed in the axial direction;
In each of the plurality of piston chambers, the cam surface is received in a reciprocating manner under the pressure of a return spring and at the time of relative rotation between the first shaft and the second shaft or between the first shaft and the third shaft. A plurality of pistons driven by
It is sandwiched between the opposed end faces of the pair of rotors and is slidably contacted with each other, and is positioned so as to be able to rotate at a predetermined angle with the housing, and functions of the intake valve and the discharge valve depending on the positional relationship with the cam crest A plurality of suction ports, a single valve body having discharge ports formed on both sides,
A high pressure chamber formed by communicating all the discharge ports of the valve body;
An orifice between the high pressure chamber, the inner wall of the housing, and the low pressure chamber formed of a space formed between the valve body, the rotor and the piston;
In the hydraulic power transmission device that transmits torque according to the rotational speed difference between the first shaft, the second shaft, and / or the third shaft,
A hydraulic power transmission device comprising: a shut-off valve for closing the orifice when the pressure in the high pressure chamber exceeds a predetermined value.
In the hydraulic power transmission device according to claim 1,
A hydraulic power transmission device comprising a relief valve that opens the high pressure chamber when the pressure in the high pressure chamber exceeds a predetermined value.

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