JP2005282597A - Right and left drive force distributing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the cavitation from occurring in a hydraulic motor. <P>SOLUTION: The right and left drive force distributing device 1 is comprised of a planetary gear differential 20 to distribute and transmit power to right and left axle shafts 3, 4, the hydraulic motor 40 to impart relatively rotational force to the axle shafts 3, 4, and a hydraulic mechanism 60 to rotate and drive this. The hydraulic motor 40 is comprised of a cylinder block 43 connected to the front end of the axle shaft 3, and a cam ring 47 arranged outside there. The hydraulic mechanism 60 is comprised of an operating control valve 63 to control the supply and discharge of working fluid into the hydraulic motor 40, a pump oil passage 65, provided with a hydraulic pump 61 to communicate to a tank T and the operating control valve 63, a tank oil passage 67, provided with a second throttle 75, and communicated to the tank T and the operating control valve 63, a return oil passage 69, provided with a pressure control valve 77 and the first throttle 73, branched from the pump oil passage 65, and communicated to the tank T, and a bypass oil passage 71 to communicate the return oil passage 69 and the tank oil passage 67. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a left / right driving force distribution device that distributes driving force transmitted to left and right wheels.

  In such a right and left driving force distribution device 80, as shown in FIG. 3 (cross-sectional view), the rotational driving force of the propeller shaft 5 that rotates by receiving the driving force from the engine is transmitted via a gear such as a drive pinion 6. The differential case 10 transmitted to the differential case 10, the differential device 20 that distributes and transmits the driving force input to the differential case 10 to the left and right axles 3, 4 by the planetary gear mechanism, and the relative rotational force to the left and right axles 3, 4. There is a configuration including a hydraulic motor 40 to be applied and a hydraulic mechanism 81 that rotationally drives the hydraulic motor 40 by controlling supply and discharge of hydraulic oil discharged from the hydraulic pump 61 to the hydraulic motor 40 (Patent Document). 1).

  The hydraulic motor 40 provided in the left and right driving force distribution device 80 is of a radial plunger type, and holds a plurality of plungers 45 so as to be movable forward and backward in a radial manner, and is connected to the tip end portion of the left axle 3. 3 and a cam ring 47 which is disposed on the outer periphery of the cylinder block 43 and is engaged with the tip of the plunger 45 and connected via the planetary gear mechanism of the differential device 20. It becomes. The hydraulic motor 40 is formed with two supply / discharge oil passages 50 and 51 for allowing the hydraulic oil supplied and discharged from the hydraulic mechanism 81 to flow to the plurality of plungers 45, and the plurality of plungers 45 are divided into two groups. The supply / discharge oil passage 50 is connected to one set of plungers 45, and the supply / discharge oil passage 51 is connected to the other pair of plungers 45. The hydraulic oil discharged from the hydraulic pump 61 and supplied and discharged by the operation control valve 63 moves the plunger 45 forward and backward through the pair of supply and discharge oil passages 50 and 51, and moves the cam ring 47 relative to the cylinder block 43. Rotating force is applied to the axles 3 and 4 by rotating.

  The hydraulic mechanism 81 is an operation control valve 63 that communicates with the two supply / discharge oil passages 50 and 51, and a pump that communicates between the tank and the operation control valve 63 and supplies hydraulic oil discharged from the hydraulic pump to the operation control valve 63. An oil passage 65, a tank T communicating with the tank T and the operation control valve 63, a tank oil passage 67 for returning the hydraulic oil discharged from the hydraulic motor 40 to the tank T, and between the operation control valve 63 and the hydraulic pump 61. It has a relief oil passage 82 communicating with the pump oil passage 65 and the tank oil passage 67, and a relief valve 83 provided in the relief oil passage 82. When the operation control valve 63 is in the neutral state, the pair of oil supply / discharge oil passages 50 and 51 communicate with the tank T, and the cylinder block 43 and the cam ring 47 of the hydraulic motor 40 are in a free state. 4, an equal driving force is transmitted from the propeller shaft 5 through the differential device 20. Further, when the operation control valve 63 is alternately switched between the left side and the right side, the hydraulic oil discharged from the hydraulic pump 61 is controlled to be supplied to and discharged from the hydraulic motor 40, and the hydraulic motor 40 is rotationally driven.

JP 2001-199254 A

  The differential device of the left and right driving force distribution device configured as described above is configured such that, for example, when the left wheel among left and right wheels slips and the load acting on the left axle is reduced, the load on the left side is reduced. Rotate the axle at high speed. Then, the cylinder block of the hydraulic motor connected to the left axle rotates at high speed in the same direction as the axle, and the hydraulic motor operates as a pump. The hydraulic motor normally operates so that the cam ring rotates with respect to the cylinder block. However, when the hydraulic motor operates as a pump, the cylinder block rotates with respect to the cam ring and operates in the direction opposite to the motor operation. As a result, the direction of the hydraulic oil flowing through the pair of supply / discharge oil passages is reversed. Here, since the supply / discharge oil passage is an oil passage for applying hydraulic pressure to the plunger, the diameter of the oil passage is small. For this reason, when the hydraulic motor operates as a pump, hydraulic oil must be sucked through the small oil supply / discharge oil passage. In addition, the pumped hydraulic motor has a small suction force. For this reason, the hydraulic oil is not sufficiently sucked by the hydraulic motor.

  As a result, cavitation tends to occur in the suction-side oil supply / discharge passage, and abnormal noise is generated in the discharge-side supply / discharge passage, and if this abnormal noise continues for a long time, the hydraulic motor, etc. is damaged. Problem occurs.

  Therefore, a hydraulic motor having a large capacity may be used to increase the suction force, or the diameter of the supply / discharge oil passage may be enlarged. However, there arises a problem that the entire right and left driving force distribution device is enlarged.

  The present invention has been made in view of such a problem, and does not increase the size of the entire apparatus, and the right and left driving force distribution in which cavitation does not occur in the supply / discharge oil passage when the axle on one side rotates at a high speed. An object is to provide an apparatus.

  The invention according to claim 1 includes a differential gear having a planetary gear mechanism that distributes and transmits the driving force transmitted from the engine to the left and right axles, and a hydraulic motor that applies a relative rotational force to the left and right axles. And a hydraulic mechanism for rotating and driving the hydraulic motor by controlling supply and discharge of the hydraulic oil discharged from the hydraulic pump to the hydraulic motor. The hydraulic motor has a first supply and discharge for flowing the hydraulic oil supplied and discharged from the hydraulic mechanism. In the left / right driving force distribution device in which the oil passage and the second supply / discharge oil passage are formed, the hydraulic mechanism communicates hydraulic oil discharged from the hydraulic pump in communication with the first supply / discharge oil passage and the second supply / discharge oil passage. An operation control valve that controls supply and discharge of the hydraulic motor, a pump oil passage that is provided with a hydraulic pump, communicates with the tank and the operation control valve, and flows hydraulic oil discharged from the hydraulic pump to the operation control valve; a tank and an operation control valve; Hydraulic fluid discharged from the hydraulic motor in communication with A tank oil passage that returns to the tank, a return oil passage that communicates with the pump oil passage between the hydraulic pump and the operation control valve and the tank, and discharges the hydraulic oil that is discharged from the hydraulic motor and flows back through the pump oil passage to the tank side, A bypass oil passage that communicates with the return oil passage and the tank oil passage and flows the hydraulic oil flowing through the return oil passage to the tank oil passage, and a return oil passage on the tank side from the position where the return oil passage and the bypass oil passage intersect The first flow rate control valve provided in the tank (for example, the first throttle 73 in the embodiment) and the second flow rate control valve provided in the tank oil passage on the tank side from the position where the tank oil passage and the bypass oil passage intersect. (For example, the second throttle 75 in the embodiment) and the oil pressure on the upstream side of the return oil passage exceeds the predetermined value provided in the return oil passage on the upstream side from the position where the return oil passage and the bypass oil passage intersect. Only allow the flow of hydraulic oil downstream And characterized by having a force control valve.

  According to the left and right driving force distribution device according to claim 1, the bypass oil communicating with the tank is provided in the pump oil passage between the hydraulic pump and the operation control valve, and the return oil passage is communicated with the tank oil passage. A first flow control valve is provided in the return oil path on the tank side from the position where the return oil path and the bypass oil path intersect, and the tank oil on the tank side from the position where the tank oil path and the bypass oil path intersect. A second flow control valve is provided on the road, and a pressure control valve is provided on the return oil path upstream from the position where the return oil path and the bypass oil path intersect, so that one of the axles rotates at a high speed and the hydraulic motor is pumped. As a result, the hydraulic oil discharged from the hydraulic motor flows back through the pump oil passage through the operation control valve and flows into the return oil passage. When the oil passage in the return oil passage exceeds a predetermined value, the pressure control valve is opened to bring the return oil passage into communication, and the backflowing hydraulic fluid flows in the return oil passage to the tank side. Then, most of the hydraulic oil that flows backward flows through the bypass oil passage and flows into the tank oil passage, and the remaining hydraulic oil is returned to the tank through the first flow control valve. And most of the hydraulic fluid that flows backward flows in the tank oil passage to the operation control valve side, and flows into the supply / discharge oil passage where the suction force is acting via the operation control valve. The remaining hydraulic oil is returned to the tank through the second flow control valve. As a result, hydraulic oil is supplied to the supply / exhaust oil passage where the hydraulic pressure is reduced, so that cavitation can be prevented from occurring in the hydraulic motor, and damage to the hydraulic motor and the like can be prevented. it can.

  According to the left and right driving force distribution device according to the present invention, a return oil passage communicating with the tank is provided in the pump oil passage between the hydraulic pump and the operation control valve, and the bypass oil passage communicating with the tank oil passage is provided in the return oil passage. A first flow rate control valve is provided in the return oil path on the tank side from the position where the return oil path and the bypass oil path intersect, and the tank oil path on the tank side from the position where the tank oil path and the bypass oil path intersect A second flow rate control valve is provided in the valve, and a pressure control valve is provided in the return oil path upstream from the position where the return oil path and the bypass oil path intersect, thereby discharging the hydraulic motor back to the pump oil path. Oil can be supplied to the return oil path, the bypass oil path, and the tank oil path to the supply / discharge oil path where the oil pressure is reduced. Therefore, cavitation can be prevented from occurring in the hydraulic motor, and damage to the hydraulic motor or the like can be prevented.

  A preferred embodiment of a left / right driving force distribution apparatus according to the present invention will be described below with reference to FIGS. In the present embodiment, a left and right driving force distribution device connected to a pair of rear axles disposed on the left and right sides of a vehicle such as an automobile will be described as an example. For convenience of explanation, the directions of arrows shown in FIG. 1 (cross-sectional view) and FIG. 2 (cross-sectional view) will be described below as the front-rear direction and the left-right direction.

  As shown in FIGS. 1 and 2, the left / right driving force distribution device 1 includes a differential case 10 that is rotatably supported and rotates by receiving the driving force of the engine, and the driving force input to the differential case 10 is converted to the left and right. A differential device 20 that distributes and transmits to the axles 3 and 4, a hydraulic motor 40 that applies relative rotational force to the left and right axles 3 and 4, and hydraulic oil discharged from the hydraulic pump 61 is supplied to and discharged from the hydraulic motor 40. And a hydraulic mechanism 60 that rotationally drives the hydraulic motor 40.

  The differential case 10 is rotatably supported via bearings 14 and 15 by a housing 13 coupled to a differential carrier 12 fixed to the vehicle body. The differential case 10 rotates as the power is transmitted from the drive shaft 5 connected to the engine via the drive pinion 6 and the gear 7.

  The differential device 20 is a so-called planetary gear type, and a plurality of planetary gears 23 and sun gears 24 are used to rotate the left and right axles 3 through ring gears 21 that are rotatably supported on the inner side of the differential case. 4 and the rotational difference between the left and right axles 3 and 4 are absorbed by the rotation of the planetary gear 23. The planetary gear 23 is supported by a planetary carrier 25 disposed on both sides via a support shaft 23a so as to revolve freely. The sun gear 24 meshed with the planetarial gear 23 is connected to the left axle 3. The planetary carrier 25 is connected to the right axle 4 via side covers 41 and 42 of a hydraulic motor 40 described later.

  A hydraulic motor 40 is disposed on the right side of the differential device 20 in the housing 13 in the axial direction. The hydraulic motor 40 is of a radial plunger type, and includes a cylinder block 43 in which a plunger 45 is inserted into each of a plurality of radially extending cylinder holes 44 so as to be capable of moving forward and backward, and the cylinder block 43 is surrounded by the cylinder block 43. The cam ring 47 is arranged so as to come into contact with and contact with the tip of the plunger 45.

  The cylinder block 43 is coupled to the right end of the left axle 3 that extends in the left-right direction, and rotates together with the axle 3. The plunger 45 inserted into the cylinder hole 44 is always urged toward the cam ring by a spring 46. At the bottom of each of the plurality of cylinder holes 44, there is formed an internal oil passage 48 having one end opened to the cylinder hole bottom, the other end extended to the differential mechanism side, and the other end opened to the outer periphery. The other internal oil passages 48 are arranged in pairs in the circumferential direction and communicate with each other. When hydraulic oil is supplied to one set, the hydraulic oil is discharged from the other set. It has become. One set of internal oil passages 48 is referred to as a first supply / discharge oil passage 50, and the other set of internal oil passages 48 is referred to as a second supply / discharge oil passage 51.

  The cylinder block 43 and the side covers 41 and 42 are supported via bearings 53 and 54 so as to be relatively rotatable. The side cover 41 disposed on the left side forms a boss portion 41 a extending in the left direction of the axle, and the boss portion 41 a is splined to the planetary carrier 25. Therefore, the outer ring of the hydraulic motor 40 constituted by the cam ring 47 and the side covers 41 and 42 rotates integrally with the differential case 10.

  The first supply / discharge oil passage 50 and the second supply / discharge oil passage 51 have a first communication oil passage 57 that communicates with the first supply / discharge oil passage 50 and a second communication oil passage that communicates with the second supply / discharge oil passage 51. A hydraulic mechanism 60 is connected via 58. The hydraulic mechanism 60 includes an operation control valve 63 that controls supply and discharge of hydraulic oil discharged from the hydraulic pump 61 to the hydraulic motor 40 via the first communication oil passage 57 and the second communication oil passage 57, and the hydraulic pump 61. The hydraulic oil discharged from the hydraulic pump 61 in communication with the tank T and the operation control valve 63 is discharged from the hydraulic motor 40 in communication with the pump oil passage 65 that flows to the operation control valve 63 and the tank T and the operation control valve 63. The hydraulic oil is discharged from the hydraulic motor 40 and flows backward through the pump oil passage 65 in communication with the tank oil passage 67 for returning the hydraulic oil to the tank T, the pump oil passage 65 between the hydraulic pump 61 and the operation control valve 63, and the tank T. A return oil passage 69 for flowing hydraulic oil to the tank T side, a bypass oil passage 71 for communicating the return oil passage 69 and the tank oil passage 67 and flowing the hydraulic oil flowing through the return oil passage 69 to the tank oil passage 67, and a return Oilway 69 and Viper A first throttle 73 provided in the return oil passage 69 on the tank side from the position P1 where the oil passage 71 intersects, and a tank oil passage 67 on the tank side from the position P2 where the tank oil passage 67 and the bypass oil passage 71 intersect. Is provided in the return oil passage 69 upstream from the position P1 where the return oil passage 69 and the bypass oil passage 71 intersect, and the oil pressure upstream of the return oil passage 69 has a predetermined value. And a pressure control valve 77 that permits the flow of hydraulic oil to the downstream side only when the pressure is exceeded.

  The operation control valve 63 is a two-position, four-port electromagnetic direction switching valve. In the neutral state, the first supply / discharge oil passage 50 and the second supply / discharge oil passage 51 are connected to the first communication oil passage 57 and the second communication oil passage. 58, the first oil supply / discharge oil passage 50 and the pump oil passage 65 communicate with each other, and the second oil supply / discharge oil passage 51 and the tank oil passage 67 communicate with each other. When switched to the other side, the second supply / discharge oil passage 51 and the pump oil passage 65 communicate with each other, and the first supply / discharge oil passage 50 and the tank oil passage 67 communicate with each other. The operation of the operation control valve 63 is controlled by a controller (not shown).

  Next, the operation of the left / right driving force distribution apparatus 1 according to the present invention will be described. When the operation control valve 63 is in the neutral state, as described above, the first supply / discharge oil passage 50 and the second supply / discharge oil passage 51 (hereinafter, these are collectively referred to as “supply / discharge oil passages 50, 51”). ) Communicates with the tank T, the cylinder block 43 of the hydraulic motor 40 is in a free state. Therefore, the driving force transmitted from the engine to the differential case 10 via the propeller shaft 5 is transmitted to the left and right axles 3 and 4 by the differential device 20.

  From this state, when the operation control valve 63 is switched to one side by the controller, the first supply / discharge oil passage 50 and the pump oil passage 65 communicate with each other, and the second supply / discharge oil passage 51 and the tank oil passage 67, high pressure hydraulic oil is supplied to half of the internal oil passages 48 of the cylinder block 43 through the first supply / discharge oil passage 50, and hydraulic oil is supplied from the remaining half of the internal oil passages 48. 2 is returned to the tank T through the supply / discharge oil passage 51. For this reason, the cam ring 47 is relatively rotated to one side by the plunger 45 in the cylinder block 43 of the hydraulic motor 40. When the operation control valve 63 is switched to the other side, the second supply / discharge oil passage 51 and the pump oil passage 65 communicate with each other, and the first supply / discharge oil passage 50 and the tank oil passage 67 communicate with each other, High-pressure hydraulic oil is supplied to half of the internal oil passages 48 of the cylinder block 43 through the second supply / discharge oil passage 51, and hydraulic oil passes through the first supply / discharge oil passage 50 from the remaining half of the internal oil passages 48. Through this, the tank T is returned to the tank T, and the relative rotation operation on one side of the cam ring 47 is continued.

  As a result, the differential case 10 and the sun gear 24 rotate in the same direction via the planetary carrier 25 splined to the boss portion 41 a of the side cover 41, and a rotational force is applied to the left axle 3. Directly acts between the left and right axles 3 and 4 to cause a rotational difference.

  Here, when a wheel acting on the left axle 3 of the left and right axles 3 and 4 slips or the like and the load acting on the axle 3 is reduced, the differential device 20 has the left side where the load is reduced. The axle 3 is rotated at high speed. Then, the cylinder block 43 of the hydraulic motor 40 connected to the left axle 3 rotates at high speed in the same direction as the axle 3, and the hydraulic motor 40 operates as a pump. That is, the hydraulic motor 40 operates so that the cam ring 47 rotates with respect to the cylinder block 43 when operating as a motor, but when the cylinder block 43 rotates with respect to the cam ring 47, that is, the hydraulic motor 40 operates as a motor. When operating in the opposite direction, it operates as a pump.

  For this reason, the hydraulic motor 40 discharges the hydraulic oil to one of the supply / discharge oil passages 50 and 51 and sucks the hydraulic oil from the other of the supply / discharge oil passages 50 and 51. Here, when the hydraulic motor 40 performs a pump operation, the hydraulic motor 40 performs pumping operation using a negative pressure generated in the motor as a suction source, but the generated negative pressure is a small pressure of about 0.06 MP. The suction power of hydraulic oil is weak. Further, the diameters of the supply / discharge oil passages 50 and 51 are small. For this reason, there exists a possibility that cavitation may generate | occur | produce easily in the supply / discharge oil path 50 and 51 of the side which attracts | sucks hydraulic fluid. However, the left / right driving force distribution device 1 according to the present invention causes the hydraulic oil discharged from the hydraulic motor 40 to flow back into the pump oil passage 65 via the operation control valve 63 and flow into the return oil passage 69. When the oil pressure in the return oil passage 69 exceeds a predetermined pressure, the pressure control valve 77 is opened to bring the return oil passage 69 into communication, and the high-pressure hydraulic oil that flows backward flows to the tank side and enters the bypass oil passage 71. Inflow. Since the first throttle 73 is provided on the downstream side of the return oil passage 69, the hydraulic oil that flows backward flows into the bypass oil passage 71 in a high pressure state.

  Then, the backward flowing hydraulic oil flowing through the bypass oil passage 71 flows into the tank oil passage 67 and flows toward the operation control valve 63 side. That is, since the second throttle 75 is provided on the tank side of the tank oil passage 67, the flow rate of the hydraulic oil flowing into the tank oil passage 67 to the tank side is limited by the second throttle 75. For this reason, most of the hydraulic fluid that has flowed into the tank oil passage 67 can flow to the operation control valve 63 side in a high-pressure state. As a result, the hydraulic oil that has flowed back flows into the first supply / discharge oil passage 50 or the second supply / discharge oil passage 51 on the suction side through the operation control valve 63 to increase the oil pressure in the oil passage. For this reason, while being able to improve the suction | inhalation property of the hydraulic fluid by the hydraulic motor 40, generation | occurrence | production of the cavitation in the supply / discharge oil path 50 and 51 can be prevented.

  As described above, in the left / right driving force distribution device 1 according to the present invention, when the hydraulic motor 40 performs a pump operation, the hydraulic oil discharged from the hydraulic motor 40 is increased in pressure to communicate with the suction side of the hydraulic motor 40. Since the oil is supplied to the passage 50 or the second oil supply / discharge passage 51, the occurrence of cavitation in the oil supply / discharge oil passages 50, 51 can be prevented. For this reason, it is not necessary to increase the size of the hydraulic motor 40 or increase the supply / discharge oil passages 50 and 51 in order to increase the suction force of the hydraulic oil, and to prevent the left and right driving force distribution device 1 from increasing in size. Can do. Further, the left / right driving force distribution device 1 according to the present invention has a simple configuration because the return oil passage 69, the bypass oil passage 71, the first throttle 73 and the second throttle 75 are only added compared to the conventional configuration. Thus, an increase in the cost of the apparatus can be suppressed.

1 is a cross-sectional view of a left / right driving force distribution device according to an embodiment of the present invention. The partial enlarged view of this right-and-left driving force distribution apparatus is shown. Sectional drawing of the conventional left-right driving force distribution apparatus is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Left-right drive force distribution device 3, 4 Axle 20 Differential device 40 Hydraulic motor 50 1st supply / discharge oil path 51 2nd supply / discharge oil path 60 Hydraulic mechanism 61 Hydraulic pump 63 Actuation control valve 65 Pump oil path 67 Tank oil path 69 Return oil passage 71 Bypass oil passage 73 First throttle (first flow control valve)
75 Second throttle (second flow control valve)
77 Pressure control valve P1, P2 Position T Tank

Claims (1)

A differential device having a planetary gear mechanism that distributes and transmits the driving force transmitted from the engine to the left and right axles, a hydraulic motor that applies a relative rotational force to the left and right axles, and a hydraulic pump And a hydraulic mechanism that rotationally drives the hydraulic motor by controlling the supply and discharge of the hydraulic oil to the hydraulic motor, and the hydraulic motor includes a first supply / discharge oil path through which the hydraulic oil supplied and discharged from the hydraulic mechanism flows. In the left / right driving force distribution device in which the second supply / discharge oil passage is formed,
The hydraulic mechanism is
An operation control valve that communicates with the first supply / discharge oil passage and the second supply / discharge oil passage and controls supply / discharge of the hydraulic oil discharged from the hydraulic pump to the hydraulic motor;
A pump oil passage which is provided with the hydraulic pump and communicates with the tank and the operation control valve to flow the hydraulic oil discharged from the hydraulic pump to the operation control valve;
A tank oil passage communicating with the tank and the operation control valve to return the hydraulic oil discharged from the hydraulic motor to the tank;
A return oil passage that communicates with the pump oil passage between the hydraulic pump and the operation control valve and the tank and is discharged from the hydraulic motor and flows back to the tank with the hydraulic oil that flows back through the pump oil passage;
A bypass oil passage that communicates with the return oil passage and the tank oil passage and flows the working oil flowing through the return oil passage to the tank oil passage;
A first flow rate control valve provided in the return oil path on the tank side from a position where the return oil path and the bypass oil path intersect;
A second flow rate control valve provided in the tank oil passage on the tank side from a position where the tank oil passage and the bypass oil passage intersect;
It is provided in the return oil path upstream from the position where the return oil path and the bypass oil path intersect, and only when the hydraulic pressure on the upstream side of the return oil path exceeds a predetermined value, A right / left driving force distribution device comprising a pressure control valve that allows flow.

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