JP2005282599A - Right and left drive force distributing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the cavitation from occurring at high speed traveling. <P>SOLUTION: The right and left drive force distributing device 1 is comprised of a rotatably supported differential case 10, a differential 20 provided with a planetary gear mechanism to distribute the drive force input into it to right and left axle shafts 3, 4, a hydraulic motor 50 to impart relatively rotational force to the axle shafts 3, 4, and a hydraulic pump 70 to rotate and drive the hydraulic motor 50 by the rotation following the rotation of the differential case 10. The hydraulic motor 50 is comprised of an outer wheel 64 having an opening 28 in a housing 17 and rotatably supported, and a cylinder block 57 arranged inside to rotate an outer wheel 64 by the supply and discharge control of the working fluid from the hydraulic pump 70 to store the working fluid in the opening 28. The interval between a pump oil passage 55 and the opening 28 connected to the hydraulic pump 70 is linked with a communicating oil passage 54, and a plurality of impeller members 91 to flow and feed the working fluid in the opening 28 into the hydraulic pump 70 is installed in the outside of the outer wheel 64. <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.

  Such a left and right driving force distribution device includes a differential case to which the rotational driving force of a propeller shaft that is rotatably supported and connected to the engine side is transmitted via a gear, and the driving force that is input to the differential case. A differential device that distributes and transmits to the left and right axles by a planetary gear mechanism, a hydraulic motor that applies a relative rotational force to the left and right axles, and a hydraulic pump that rotationally drives the hydraulic motor (See Patent Document 1).

  The hydraulic motor provided in the left / right driving force distribution device is of a radial plunger type, and includes a cylinder block in which a plurality of plungers are radially held back and forth, and a distal end of the plunger arranged on the outer periphery of the cylinder block. And a cam ring connected via a planetary gear mechanism of the differential. The hydraulic motor is configured such that a plunger that is discharged from a hydraulic pump and moves forward and backward by hydraulic oil that is supplied and discharged by a direction switching valve urges a cam ring to apply a rotational force to an axle.

  Similar to the hydraulic motor, the hydraulic pump is of a radial plunger type, and includes a cylinder block that holds a plurality of plungers so as to be movable back and forth, and a cam ring that is disposed on the outer periphery of the hydraulic pump. In the cam ring, a gear formed on the outer periphery of the differential case rotates by transmitting a driving force to a driving gear provided on a pump shaft of the hydraulic pump via an idle gear. The pump shaft is integrally attached to the cylinder block. For this reason, when the pump shaft rotates, the cylinder block rotates, the plunger moves forward and backward, and the hydraulic pump operates as a pump.

  Thus, since the cylinder block of the hydraulic pump is connected to the propeller shaft via the idle gear and the differential case, when the vehicle travels at a low speed, the cylinder block also rotates at a low speed due to a decrease in the speed of the propeller shaft. become. For this reason, the discharge amount of the hydraulic pump is reduced, and there is a possibility that the hydraulic pump cannot supply the minimum flow rate required to operate the hydraulic motor to the hydraulic motor. Therefore, when the vehicle travels at a low speed, an idle gear having a predetermined gear ratio is used so that the rotational speed of the hydraulic pump becomes a rotational speed at which the minimum flow rate can be discharged.

JP 2001-199254 A

  In the hydraulic pump rotating in this way, when the vehicle travels at a high speed, the cylinder block may further rotate at a higher speed by the idle gear, and may exceed a limit rotational speed at which hydraulic oil can be drawn from the tank. As a result, the pressure in the pump oil passage, which is the oil passage on the suction side of the hydraulic pump, is reduced, gas dissolved in the oil is evaporated, and so-called cavitation occurs in which a void is formed in the pump oil passage. When cavitation occurs, the space in the oil passage connected to the hydraulic motor on the discharge side of the hydraulic pump is crushed at high pressure, reducing the amount of hydraulic fluid flowing in this oil passage, and abnormal noise is generated when the space disappears. If this occurs or if abnormal noise continues for a long time, the hydraulic mechanism or the like may be damaged.

  Therefore, a hydraulic pump having a large capacity capable of discharging a minimum amount of hydraulic fluid from the hydraulic motor when the vehicle is traveling at a low speed may be used. However, as the capacity increases, the hydraulic pump becomes larger and the hydraulic motor In addition, the oil passage for supplying and discharging the hydraulic oil becomes larger, resulting in a problem that the entire left and right driving force distribution device is enlarged.

  The present invention has been made in view of such problems, and does not increase the size of the entire device, and does not cause cavitation in an oil passage connected to a hydraulic pump when the vehicle travels at a high speed. An object is to provide a power distribution device.

  The invention according to claim 1 is a differential case that is rotatably supported and rotates by receiving the driving force of the engine, a differential device that distributes and transmits the driving force input to the differential case to the left and right axles, The hydraulic motor is driven to rotate through a hydraulic motor that applies a relative rotational force to the axle and a gear that rotates with the rotation of the differential case (for example, the idle gear 11 and the spur gear 71 in the embodiment). In the left and right driving force distribution device having a hydraulic pump to be driven, the hydraulic motor is discharged from the hydraulic pump supported inside the outer ring with a gap in the housing and supported rotatably inside the outer ring. It has an inner ring (for example, cylinder block 57 in the embodiment) that rotates the outer ring by hydraulic oil supply / discharge control, and hydraulic oil leaked from the hydraulic motor or the like is stored in the gap. A left and right driving force distribution device, which is provided with a communication oil passage that connects between a pump oil passage connected to the upstream side of the hydraulic pump and the clearance, and the hydraulic oil stored in the clearance is communicated in the clearance by a rotating outer ring. A hydraulic oil supply device is provided that flows through the oil passage and the pump oil passage to supply the hydraulic pump.

  According to a second aspect of the present invention, in the left / right driving force distribution device according to the first aspect, the hydraulic oil supply device is provided on the outer surface of the outer ring and protrudes into the gap (for example, the blade in the embodiment). A plurality of members 91) are provided.

  According to the left / right driving force distribution device according to claim 1, the pump oil connected to the upstream side of the hydraulic pump by disposing the outer ring of the hydraulic motor so as to form a gap with the housing and storing hydraulic oil in the gap. By connecting the road and the gap with a communication oil path, and by providing a hydraulic oil supply device that supplies hydraulic oil to the hydraulic pump by flowing the hydraulic oil in the gap to the communication oil path and the pump oil path by a rotating outer ring in the gap, When the vehicle travels, the hydraulic pump is pumped through the differential case and the gear, and the hydraulic oil is supplied to the hydraulic motor through the pump oil passage, and the hydraulic motor applies a relative rotational force to the left and right axles. . When the hydraulic motor rotates, the hydraulic oil stored in the gap by the hydraulic oil supply device is caused to flow through the communication oil passage and the pump oil passage and is supplied to the hydraulic pump. For this reason, when the vehicle travels at a high speed, even if the hydraulic pump rotates at a high speed and the hydraulic pressure in the pump oil path decreases, the hydraulic oil supply device that operates in conjunction with the rotating hydraulic motor rotates the pump oil path. The hydraulic oil in the gap is forcibly supplied. For this reason, pressure reduction of the pump oil passage can be prevented, and the occurrence of cavitation can be prevented in advance. For this reason, the operation of the hydraulic system is stabilized, and damage to the hydraulic mechanism and the like can be prevented in advance.

  According to the left and right driving force distribution device according to claim 2, the hydraulic oil supply device has a plurality of convex portions provided on the outer surface of the outer ring and projecting into the gap, so that when the outer ring rotates, The convex portion rotates in the gap and forcibly causes the hydraulic oil stored in the gap to flow into the communication oil passage. Therefore, it is possible to provide a left / right driving force distribution device that can prevent cavitation from occurring with a simple configuration.

  According to the left / right driving force distribution device according to the present invention, the outer ring of the hydraulic motor is disposed with a gap formed between the housing, the hydraulic oil is stored in the gap, and the pump oil passage and the gap are connected to the communication oil passage. The hydraulic fluid is connected to the hydraulic fluid pump and the hydraulic fluid pump and the hydraulic fluid is supplied to the hydraulic pump by supplying the hydraulic fluid in the gap to the hydraulic fluid pump and the hydraulic fluid pump. Even if the hydraulic pressure of the pump is reduced, hydraulic oil in the gap is forcibly supplied to the pump oil passage by the hydraulic oil supply device, so that the pressure reduction of the pump oil passage is prevented and cavitation is prevented in advance. be able to. As a result, the operation of the hydraulic system can be stabilized and damage to the hydraulic mechanism and the like can be prevented beforehand.

  Further, the hydraulic oil supply device includes a plurality of convex portions provided on the outer surface of the outer ring and protruding into the gap, thereby forcibly connecting the hydraulic oil stored in the gap with a simple configuration. It is possible to provide a hydraulic oil supply device that can be flowed into the tank.

  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) will be described below as the front-rear direction and the left-right direction.

  As shown in FIGS. 1 and 2 (schematic diagram), the left / right driving force distribution device 1 is supported rotatably and receives a driving force of the engine to rotate, and a drive input to the differential case 10. A differential 20 that distributes and transmits force to the left and right axles 3 and 4, a hydraulic motor 50 that applies a relative rotational force to the left and right axles 3 and 4, and an idle gear that rotates as the differential case 10 rotates. And a hydraulic pump 70 that rotates and drives the hydraulic motor 50 through 11.

  The differential case 10 is rotatably supported by bearings 13 and 14 on a housing 17 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 21.

  The differential device 20 is a so-called planetary gear type, and a plurality of planetary gears 23 and sun gears 24 via a ring gear 22 that rotatably supports the rotational force transmitted to the differential case 10 inside the differential case 10. 4 and the rotation 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 51 and 52 of a hydraulic motor 50 described later.

  A hydraulic motor 50 is disposed on the right side in the axial direction of the differential device 20 in the housing 17, and the first supply / discharge oil passage 15 and the second supply / discharge oil for supplying / discharging hydraulic oil to / from the hydraulic motor 50. A passage 16 (hereinafter, these are collectively referred to as “supply / discharge oil passages 15, 16”) is formed. In addition, a hydraulic pump 70 that supplies and discharges hydraulic oil to and from the hydraulic motor 50 through the supply and discharge oil passages 15 and 16 is disposed on the left rear side of the housing 17, and hydraulic oil discharged from the hydraulic pump 70 is supplied. An operation control valve 80 for controlling the operation of the hydraulic motor 50 by controlling the exhaust is provided.

  The hydraulic motor 50 is of a radial plunger type and communicates with the hydraulic pump 70 via the supply / discharge oil passages 15 and 16 and communicates with a pump oil passage 55 that connects the tank T and the hydraulic pump 70. It is connected to the hydraulic pump 70 through 54. Details of the operation of the communication oil passage 54 will be described later. The hydraulic motor 50 includes a cylinder block 57 in which a plunger 59 is inserted into each of a plurality of radially extending cylinder holes 58 so as to be capable of moving forward and backward, and is disposed outside the cylinder block 57 so as to surround the cylinder block 57. It has a cam ring 61 in contact with the tip. The cylinder block 57 is slidably fitted to the right end of the axle 3 extending in the left-right direction. On the left and right sides of the cam ring 61, the above-described side covers 51 and 52 having boss portions 51a extending in the axle direction are coupled. The cylinder block 57 and the side covers 51 and 52 are supported via bearings 62 and 63 so as to be relatively rotatable.

  A boss portion 51 a of the side cover 51 disposed on the left side is splined to the planetary carrier 25. For this reason, the outer ring 64 of the hydraulic motor 50 including the cam ring 61 and the side covers 51 and 52 rotates integrally with the differential case 10.

  The plunger 59 inserted into the cylinder hole 58 is always urged toward the cam ring by a spring. At the bottom of each of the plurality of cylinder holes 58, there is formed an internal oil passage 57a having one end opened to the cylinder hole bottom, the other end extending to the differential mechanism side, and the other end opened to the outer periphery. The oil passages 15 and 16 communicate with each other. The internal oil passages 57a are arranged in pairs in the circumferential direction, and when hydraulic oil is supplied to one set, the hydraulic oil is discharged from the other set. Yes. The inner peripheral surface of the cam ring 61 gives a continuous rotational motion from the plunger 59 to the cam ring 61 when hydraulic oil is alternately supplied to and discharged from one set and the other set of the internal oil passage 57a. It is formed into a shape.

  A gap 28 is formed between the outer ring 64 of the hydraulic motor 50 and the housing 17 so that the outer ring 64 can rotate. The clearance 28 is formed on the outer side of the radial end of the outer ring 64, and hydraulic fluid leaking from the hydraulic motor 50 or the like is stored in the clearance 28. The stored hydraulic fluid is sealed so as not to leak out from the housing 17. A communication hole 30 is opened at a lower portion of the housing 17 that accommodates the hydraulic motor 50, and the communication oil passage 54 described above is connected to the communication hole 30. Accordingly, the gap 28 communicates with the communication oil passage 54 through the communication hole 30.

  On both side surfaces of the pair of side covers 51, 52 forming the outer ring 64, as shown in FIG. 3A, a hydraulic oil supply device 90 for flowing hydraulic oil stored in the gap 28 to the communication oil passage 54 side is provided. Is provided. The hydraulic oil supply device 90 includes a plurality of convex blade members 91 that are attached to the side surfaces of the pair of side covers 51 and 52 and project into the gap 28. The blade member 91 is disposed at a predetermined interval from another adjacent blade member 91, and the front side in the rotational direction is curved in a concave shape. Therefore, when the outer ring 64 rotates in the direction of arrow A, the hydraulic oil stored in the gap 28 is urged and flows by the plurality of blade members 91 and flows into the communication oil passage 54 through the communication hole 30. To do. As shown in FIG. 3B, the blade member 91 may be additionally provided on the outer peripheral surface of the outer ring 64 so as to protrude into the gap 28, or may be provided only on the outer peripheral surface of the outer ring 64. .

  As shown in FIGS. 1 and 2 again, the hydraulic pump 70 is of a radial plunger type and is disposed on the rear side of the housing 17 substantially in parallel with the axles 3 and 4, and as the differential case 10 rotates. The pump is driven to rotate. That is, a spur gear 71 is integrally formed on the outer periphery of the differential case 10, and the spur gear 71 is connected to the pump shaft of the hydraulic pump 70 via the idle gear 11 disposed between the housing 17 and the hydraulic pump 70. The rotational force is transmitted to a drive gear 72 a provided at 72. The spur gear 71 and the idle gear 11 are configured to have a predetermined gear ratio in order to increase the rotational speed of the hydraulic pump 70 with respect to the rotational speed of the differential case 10.

  The hydraulic pump 70 is rotatably supported in a pump casing 73 extending substantially parallel to the housing 17, and a cylinder block 74 in which a plurality of plungers 75 are inserted into a cylinder hole 76 so as to be movable back and forth, and the cylinder block 74. And a cam ring 77 disposed on the outside of 74. The cylinder block 74 is formed with a first communication oil passage 78 that opens to the bottom of each cylinder hole 76 and a second communication oil passage 79 that communicates with the tip opening of each cylinder hole 76. The first communication oil path 78 and the second communication oil path 79 supply and discharge hydraulic oil to and from the hydraulic motor 50 via the supply / discharge oil paths 15 and 16. Each cylinder hole 76 communicates with the tank T via a first communication oil passage 78, a second communication oil passage 79, and an intake pipe 69.

  A one-way clutch is provided between the left side of the pump shaft 72 in the pump casing 73 and the drive gear 72a to allow the hydraulic pump 70 to operate during forward travel of the vehicle and to restrict the operation of the hydraulic pump 70 during reverse travel. Yes. Accordingly, when the vehicle travels forward, the pump shaft 72 rotates and the cylinder block 74 rotates, and the plungers 75 move forward and backward to pump the hydraulic pump 70.

  The operation control valve 80 disposed on the rear side of the hydraulic pump 70 is a two-position, four-port electromagnetic directional control valve. In the neutral state, the first supply / discharge oil passage 15 and the second supply / discharge oil passage 16 are tanks. When connected to the tank oil passage 83 connected to T and switched to one side, the first supply / discharge oil passage 15 and the pump oil passage 55 are connected, and the second supply / discharge oil passage 16 and the tank oil passage 83 are connected. When switched to the other side, the second supply / discharge oil passage 16 and the pump oil passage 55 communicate with each other, and the first supply / discharge oil passage 15 and the tank oil passage 83 communicate with each other. The operation of the operation control valve 80 is controlled by a controller (not shown).

  Next, the operation of the left / right driving force distribution device 1 according to the present invention will be described for the case where the vehicle travels at a low speed and the case where the vehicle travels at a high speed. First, a case where the vehicle travels at a low speed will be described. When the operation control valve 80 is in the neutral state, the pair of oil supply / discharge oil passages 15 and 16 communicate with the tank T, so that the cylinder block 57 of the hydraulic motor 50 is in a free state. Therefore, an equal driving force is transmitted from the propeller shaft 5 to the left and right axles 3 and 4 via the differential device 20.

  From this state, when the operation control valve 80 is switched to, for example, one side by the controller, the first supply / discharge oil passage 15 and the pump oil passage 55 communicate with each other, and the second supply / discharge oil passage 16 and the tank oil passage 83. And the high-pressure hydraulic oil is supplied to the half internal oil passages 57a of the cylinder block 57 through the first supply / discharge oil passage 15, and the hydraulic oil is supplied from the remaining half internal oil passages 57a to the second. The oil is returned to the tank T through the supply / discharge oil passage 16. Here, when the vehicle is traveling at a low speed, the rotational speed of the propeller shaft 5 is small, and the rotational speed of the differential case 10 connected to the propeller shaft 5 is also small. However, as described above, the hydraulic pump 70 is rotated at a high speed via the spur gear 71 and the idle gear 11 formed in the differential case 10, so that when the vehicle is traveling at a low speed, the hydraulic pump 70 is connected to the left and right axles. It is possible to ensure the discharge flow rate of the hydraulic oil necessary for causing a rotation difference between 3 and 4. For this reason, the cam ring 61 can be relatively rotated to one side by the plunger 59 in the cylinder block 57 of the hydraulic motor 50. When the cam ring 61 rotates, the blade member 91 shown in FIG. 3A also rotates in the same direction as the rotation direction of the cam ring 61, and the hydraulic oil in the gap 28 flows into the communication oil passage 54. However, even if the hydraulic pump 70 is rotated at a high speed, the hydraulic oil 70 does not rotate at a rotation speed enough to make the pump oil passage 55 have a large negative pressure, so the flow rate of the hydraulic oil flowing into the communication oil passage 54 is small. That is, when the vehicle is traveling at a low speed, the amount of hydraulic oil supplied from the communication oil passage 54 to the hydraulic pump 70 is small.

  For this reason, the differential cover 10 and the sun gear 24 rotate in the same direction via the planetary carrier 25 splined to the boss portion 51a of the side cover 51, and a rotational force is applied to the left axle 3. As a result, the rotational force of the hydraulic motor 50 acts directly between the left and right axles 3 and 4 to cause a rotational difference. On the other hand, since the operation when the operation control valve 80 is switched to the other side is the same as the case of the one side, the description thereof is omitted. When the operation control valve 80 is switched to the other side, a rotational force is applied to the right axle 4.

  Now, when the vehicle is traveling at high speed, the rotational speed of the differential cover 10 is high, and the hydraulic pump 70 also rotates at high speed. Here, if the rotational speed of the hydraulic pump 70 exceeds the suction limit rotational speed at which hydraulic oil can be sucked from the tank T, the degree of negative pressure in the pump oil passage 55 increases, and cavitation may occur. However, in the left / right driving force distribution device 1 according to the present invention, when the degree of the negative pressure of the pump oil passage 55 increases, the communicating oil is provided by the blade member 91 provided on the outer ring 64 of the hydraulic motor 50 shown in FIG. The hydraulic oil that has flowed into the passage 54 flows into the pump oil passage 55 through the communication oil passage 54 and is supplied to the hydraulic pump 70. For this reason, the pressure reduction of the pump oil passage 55 is suppressed, and the occurrence of cavitation can be prevented in advance. Further, since the hydraulic oil is forcibly supplied from the communication oil passage 54 to the pump oil passage 55 even when the hydraulic pump 70 exceeds the suction limit rotational speed, it is possible to suppress a decrease in the discharge amount of the hydraulic oil, The rotational difference between the left and right axles 3 and 4 at high speed can be surely set to a desired rotational difference.

  As described above, the left / right driving force distribution device 1 according to the present invention can prevent the pump oil passage 55 from being lowered even when the hydraulic pump 70 is rotated at a high speed. Occurrence can be prevented. In addition, since the hydraulic pump 70 having a small capacity can suppress a decrease in the discharge amount of the hydraulic oil at a high speed, the hydraulic pump 70 having a small capacity can be used, and the left and right driving force distribution device 1 can be downsized. Is possible.

  In the above-described embodiment, the hydraulic oil supply device 90 is configured by the plurality of blade members 91 provided on the outer ring 64 of the hydraulic motor 50. However, the blade member 91 is formed by forming irregularities on the outer surface of the outer ring 64. May be used instead.

1 is a cross-sectional view of a left / right driving force distribution device according to an embodiment of the present invention. The schematic diagram of this right-and-left driving force distribution apparatus is shown. The side view of the hydraulic-oil supply apparatus with which this right-and-left driving force distribution apparatus was equipped is shown.

Explanation of symbols

1 Left / right driving force distribution device 3, 4 Axle 10 Differential case 11 Idle gear (gear)
17 Housing 20 Differential device 28 Clearance 50 Hydraulic motor 54 Communication oil passage 55 Pump oil passage 57 Cylinder block (inner ring)
64 Outer ring 70 Hydraulic pump 71 Spur gear (gear)
90 Hydraulic oil supply device 91 Blade member (convex part)

Claims (2)

A differential case that is rotatably supported and rotates by receiving the driving force of the engine, a differential device that distributes and transmits the driving force input to the differential case to the left and right axles, and a relative rotation to the left and right axles In the left-right driving force distribution device, comprising: a hydraulic motor that applies force; and a hydraulic pump that rotationally drives the hydraulic motor by rotating through a gear that rotates as the differential case rotates. The motor includes an outer ring that is rotatably supported with a gap in the housing, and an inner ring that is supported on the inner side of the outer ring and that rotates the outer ring by supplying and discharging hydraulic oil discharged from the hydraulic pump. A right and left driving force distribution device that stores hydraulic oil leaked from the hydraulic motor or the like in the gap,
Providing a communication oil passage connecting the pump oil passage connected to the upstream side of the hydraulic pump and the gap;
A hydraulic oil supply device is provided in the gap for supplying hydraulic oil stored in the gap by the rotating outer ring to the communication oil passage and the pump oil passage to supply the hydraulic pump. Driving force distribution device.   The left and right driving force distribution device according to claim 1, wherein the hydraulic oil supply device includes a plurality of convex portions provided on an outer surface of the outer ring and projecting into the gap.

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