JP5727843B2 - Hydraulic power supply device for driving force distribution device - Google Patents

Description

  The present invention provides a drive force distribution device for a four-wheel drive vehicle that distributes drive force from a prime mover to main drive wheels and sub drive wheels, and supplies hydraulic pressure for generating an engagement pressure in a clutch of the drive force distribution device. The present invention relates to a hydraulic pressure supply device.

  2. Description of the Related Art Conventionally, there are four-wheel drive vehicles equipped with a driving force distribution device for distributing driving force generated by a driving source such as an engine to main driving wheels and auxiliary driving wheels. In this type of four-wheel drive vehicle, for example, when the front wheels are main drive wheels and the rear wheels are sub drive wheels, the driving force generated by the drive source is transmitted to the front wheels via the front drive shaft and the front differential. And transmitted to a driving force distribution device having a multi-plate clutch through a propeller shaft. Then, the engagement pressure of the driving force distribution device is controlled by supplying hydraulic oil of a predetermined pressure from the hydraulic pressure supply device to the driving force distribution device. As a result, the driving force of the driving source is transmitted to the rear wheels at a predetermined distribution ratio.

  Conventionally, there are hydraulic pressure supply devices disclosed in Patent Documents 1 and 2 as hydraulic pressure supply devices for supplying hydraulic pressure to the multi-plate clutch of the driving force distribution device. The hydraulic pressure supply devices disclosed in Patent Documents 1 and 2 include an electric oil pump that supplies hydraulic oil to a piston chamber that generates hydraulic pressure for pressing a multi-plate clutch, and the electric oil pump and the piston chamber are connected by a hydraulic pressure supply path. This is the configuration. However, in the above-described hydraulic pressure supply apparatus, in a system that requires quick hydraulic response, the response can be ensured by increasing the hydraulic response gain. However, since the actual hydraulic pressure will exceed the target hydraulic pressure as a compensation, this may lead to a jerky feeling or abnormal noise in the drive control of the vehicle, or to fatigue breakdown of parts. . In order to cope with such a problem, an accumulator is provided for suppressing a rapid fluctuation in the oil pressure in the piston chamber caused by the hydraulic oil being pumped by the oil pump.

  Here, in the conventional hydraulic pressure supply devices as shown in Patent Documents 1 and 2, the influence of the oil path length between the piston chamber and the oil pump and the accumulator on the hydraulic pressure fluctuation suppressing action by the accumulator is particularly taken into consideration. Absent. In other words, in the conventional structure, the operation is almost the same regardless of where the accumulator is installed in the hydraulic circuit. However, in actuality, the accumulator as described above has different oil path lengths between the oil pump and the accumulator depending on the relative positional relationship between the oil pump and the piston chamber. It is thought that the inhibitory action of sucrose changes.

  Therefore, by properly setting the arrangement relationship between the oil pump and accumulator with respect to the piston chamber, it is possible to obtain the maximum effect of suppressing fluctuations in hydraulic pressure by the accumulator. It is desirable to adopt. In addition, if the accumulator can suppress fluctuations in hydraulic pressure to the maximum, the accumulator installed in the hydraulic circuit can be miniaturized as much as possible, so the hydraulic supply device can be reduced in size and weight. It becomes.

JP 2002-187446 A JP 2007-168506 A

  The present invention has been made in view of the above points, and an object of the present invention is to arrange an accumulator in a hydraulic power supply apparatus for a driving force distribution device including an accumulator for accumulating hydraulic pressure in a piston chamber for engaging a clutch. By optimizing the configuration, it is possible to obtain the maximum hydraulic pressure fluctuation suppressing action by the accumulator and to reduce the size of the accumulator.

  The present invention for solving the above problems includes a driving force transmission path (10) for transmitting the driving force from the driving source (3) to the main driving wheels (W1, W2) and the auxiliary driving wheels (W3, W4). In the four-wheel drive vehicle (1) comprising: a drive force distribution device (20) disposed between the drive source (3) and the sub drive wheels (W3, W4) in the drive force transmission path (10). The driving force distribution device (20) generates a hydraulic pressure for driving the plurality of laminated friction materials (23) and the piston (33) for pressing and engaging the friction materials (23) in the lamination direction. An oil pump (75) for supplying hydraulic oil to the piston chamber (32), and for storing the hydraulic pressure of the piston chamber (32). A hydraulic circuit (30) composed of an accumulator (83) In the hydraulic pressure supply device (60) of the power distribution device, the piston chamber (32) is a chamber that is disposed on the outer diameter side of the rotating shaft (42) and has a substantially circular cross section when viewed from the axial direction. 32) is connected to the first opening (85) connected to the first oil passage (80) leading to the oil pump (75) and the second oil passage (81) connected to the accumulator (83). 2 openings (86) are provided, and the first opening (85) and the second opening (86) are arranged on both sides of the center (M) in the cross section of the piston chamber (32). Thus, the first opening (85) and the second opening (86) are arranged to be separated from each other within the cross section of the piston chamber (32) as much as possible.

  According to the hydraulic pressure supply device of the driving force distribution device according to the present invention, the first opening connected to the first oil passage leading to the oil pump, and the second opening connected to the second oil passage leading to the accumulator. Are arranged on both sides of the center of the circular cross section of the piston chamber so that the first opening and the second opening are spaced apart from each other within the cross section of the piston chamber as much as possible. ing. Thereby, compared with the case where the 1st opening and the 2nd opening are arrange | positioned in the position close | similar to each other in the cross section of a piston chamber, the oil_pressure | hydraulic of a piston chamber is influenced by the dynamic pressure by the drive of an oil pump. Since it becomes difficult, the deviation of the hydraulic pressure from the target hydraulic pressure can be kept small. Therefore, the effect of suppressing the hydraulic pressure fluctuation by the accumulator can be obtained to the maximum extent. In addition, since the hydraulic pressure fluctuation suppressing action by the accumulator can be obtained to the maximum, the accumulator installed in the hydraulic circuit can be downsized. Thereby, size reduction and weight reduction of a hydraulic pressure supply apparatus can be achieved.

  In the above hydraulic pressure supply device, the hydraulic oil sealing valve (76) for sealing the first oil passage (80) and sealing the hydraulic oil in the first oil passage (80), and the hydraulic oil sealing valve An on-off valve (78) for opening and closing the first oil passage (80) sealed at (76), and driving of the oil pump (75) by the motor (77) and opening / closing of the on-off valve (78) are controlled. Control means (50) for controlling the hydraulic pressure supplied to the piston chamber (32), and the control means (50) closes the open / close valve (78) and pressurizes the motor when pressurizing the piston chamber (32). By driving the oil pump (75) in (77), the piston chamber (32) is controlled to reach the target hydraulic pressure, and when the piston chamber (32) is decompressed, the oil pump by the motor (77) is used. By prohibiting the drive of (75) and opening the on-off valve (78), the piston Down chamber (32) may be controlled to be a target pressure.

In the hydraulic pressure supply device according to the present invention, the first opening and the second opening are arranged so as to be maximally separated from each other within the cross section of the piston chamber, so that the hydraulic pressure in the piston chamber drives the oil pump. It becomes difficult to be affected by dynamic pressure due to. For this reason, even when the hydraulic pressure is controlled by driving the oil pump or opening / closing the on-off valve with the hydraulic oil sealed in the first oil passage as described above, the deviation of the hydraulic pressure from the target hydraulic pressure is kept small. Is possible. Thereby, it is possible to perform quick and accurate hydraulic control. Therefore, it is possible to improve the accuracy of hydraulic control by the hydraulic supply device.
In addition, the reference code | symbol described in the parenthesis above has illustrated the code | symbol attached | subjected to the corresponding component in embodiment mentioned later for reference.

  According to the hydraulic pressure supply device of the driving force distribution device according to the present invention, by optimizing the arrangement configuration of the accumulator, it is possible to obtain the maximum effect of suppressing the hydraulic pressure fluctuation of the piston chamber by the accumulator, and to reduce the size of the accumulator. Can be planned.

It is a figure showing a schematic structure of a four-wheel drive vehicle provided with a hydraulic pressure supply device of a driving force distribution device concerning an embodiment of the present invention. It is a figure which shows the hydraulic circuit of a hydraulic supply apparatus. It is a sectional side view which shows the driving force transmission mechanism of the vehicle containing a clutch. It is a partial expanded sectional view which shows the detailed structure of a clutch. It is a figure which shows the structure of a piston chamber and its periphery, (a) is the side view (P arrow sectional drawing of FIG. 3) which looked at the piston chamber from the axial direction, (b) is A of (a). It is a figure which shows -O-A 'cross section. It is a figure which shows the external appearance structure of a piston chamber and its periphery, (a) is the side view (figure corresponding to Q arrow of FIG. 3) which looked at the piston housing from the axial direction, (b) is (a It is a figure which shows the X arrow of (). It is a graph which shows the relationship between the oil pressure change at the time of pressurization of a piston chamber by the effect | action of an accumulator, and target oil pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a four-wheel drive vehicle including a hydraulic pressure supply device for a driving force distribution device according to an embodiment of the present invention. A four-wheel drive vehicle 1 shown in the figure has an engine (drive source) 3 mounted horizontally in the front portion of the vehicle, an automatic transmission 4 installed integrally with the engine 3, and a driving force from the engine 3. A driving force transmission path 10 for transmitting to the front wheels W1, W2 and the rear wheels W3, W4 is provided.

  The output shaft (not shown) of the engine 3 includes an automatic transmission 4, a front differential (hereinafter referred to as "front differential") 5, left and right front drive shafts 6 and 6, and left and right front wheels W1 as main drive wheels. , W2. Further, the output shaft of the engine 3 is an auxiliary drive wheel via an automatic transmission 4, a front differential 5, a propeller shaft 7, a rear differential unit (hereinafter referred to as “rear differential unit”) 8, and left and right rear drive shafts 9, 9. It is connected to certain left and right rear wheels W3, W4.

  The rear differential unit 8 is connected to a rear differential (hereinafter referred to as “rear differential”) 19 for distributing driving force to the left and right rear drive shafts 9 and 9 and a driving force transmission path from the propeller shaft 7 to the rear differential 19. A front-rear torque distribution clutch 20 for cutting is provided. The front-rear torque distribution clutch 20 is a hydraulic clutch and is a driving force distribution device for controlling the driving force distributed to the rear wheels W3, W4 in the driving force transmission path 10. In addition, a hydraulic pressure supply device 60 including a hydraulic circuit 30 for supplying hydraulic oil to the front-rear torque distribution clutch 20 and a 4WD • ECU 50 as a control means for controlling the hydraulic pressure supplied by the hydraulic circuit 30 is installed. ing. The 4WD • ECU 50 is configured by a microcomputer or the like.

  The 4WD • ECU (hereinafter simply referred to as “ECU”) 50 controls the hydraulic pressure supplied by the hydraulic circuit 30 so that the front / rear torque distribution clutch (hereinafter simply referred to as “clutch”) 20 and the rear wheel W3. , W4 is controlled. Thus, drive control is performed with the front wheels W1 and W2 as main drive wheels and the rear wheels W3 and W4 as auxiliary drive wheels.

  That is, the ECU 50 detects the driving force distributed to the rear wheels W3 and W4 and the corresponding hydraulic pressure supply amount to the clutch 20 based on detection by various detection means (not shown) for detecting the traveling state of the vehicle. And a drive signal based on the calculation result is output to the clutch 20. Thus, when the clutch 20 is released (disconnected), the rotation of the propeller shaft 7 is not transmitted to the rear differential 19 side, and all the torque of the engine 3 is transmitted to the front wheels W1, W2, thereby driving the front wheels (2WD). ) State. On the other hand, when the clutch 20 is connected, the rotation of the propeller shaft 7 is transmitted to the rear differential 19 so that the torque of the engine 3 is distributed to both the front wheels W1, W2 and the rear wheels W3, W4. It becomes a drive (4WD) state. At this time, the driving force distributed to the rear wheels W3 and W4 is controlled by appropriately controlling the fastening force of the clutch 20.

  FIG. 2 is a hydraulic circuit diagram showing a detailed configuration of the hydraulic circuit 30 provided in the hydraulic pressure supply device 60. The hydraulic circuit 30 shown in the figure includes an oil pump 75 that sucks and pressures hydraulic oil stored in the oil tank 71 via a strainer 73, a motor 77 that drives the oil pump 75, and an oil pump 75 to a clutch 20. And an oil passage 70 communicating with the piston chamber 32.

  The clutch 20 includes a friction engagement portion 23 having a plurality of friction members 23 a and 23 b (see FIG. 4), a piston housing 31, and a cylinder piston that presses the friction engagement portion 23 by moving forward and backward within the piston housing 31. 33. A piston chamber 32 into which hydraulic oil is introduced is defined between the piston housing 31 and the cylinder piston 33. The cylinder piston 33 is disposed opposite to one end in the stacking direction of the plurality of friction materials 23 a and 23 b of the friction engagement portion 23. Accordingly, the cylinder piston 33 presses the friction engagement portion 23 in the stacking direction of the friction materials 23a and 23b with the hydraulic pressure of the hydraulic oil supplied to the piston chamber 32, thereby engaging the clutch 20 with a predetermined engagement pressure. It is like that.

  A check valve 76, a relief valve 74, a solenoid valve (open / close valve) 78, and a hydraulic sensor 79 are installed in this order in the oil passage 70 that communicates from the oil pump 75 to the piston chamber 32. The check valve 76 circulates hydraulic oil from the oil pump 75 side toward the piston chamber 32 side, but is configured to prevent the hydraulic oil from flowing in the opposite direction. Accordingly, the hydraulic oil sent to the downstream side of the check valve 76 by driving the oil pump 75 is referred to as an oil passage (hereinafter referred to as “enclosed oil passage”) between the check valve 76 and the piston chamber 32. Yes, it can be contained in 80. As described above, the check valve 76 is a hydraulic oil sealing valve for sealing the hydraulic oil into the oil passage 80 that leads from the oil pump 75 to the piston chamber 32. An enclosed hydraulic circuit is configured by the oil passage 80 provided with the check valve 76 and the oil pump 75.

  The relief valve 74 is opened when the pressure of the oil passage 80 between the check valve 76 and the piston chamber 32 exceeds a predetermined threshold and abnormally rises, thereby discharging hydraulic oil and increasing the oil pressure of the oil passage 80. A valve configured to release. The hydraulic oil discharged from the relief valve 74 is returned to the oil tank 71. The solenoid valve 78 is an on / off type on-off valve, and can control the opening and closing of the oil passage 80 by PWM control (duty control) based on a command from the ECU 50. Thereby, the hydraulic pressure of the piston chamber 32 can be controlled. The hydraulic oil discharged from the oil passage 80 when the solenoid valve 78 is opened is returned to the oil tank 71. The oil pressure sensor 79 is oil pressure detecting means for detecting the oil pressure of the oil passage 80 and the piston chamber 32, and the detected value is sent to the ECU 50. Further, the piston chamber 32 communicates with the accumulator 83. The accumulator 83 has an action of suppressing changes in hydraulic pressure in the piston chamber 32 and the oil passage 80. In the oil tank 71, an oil temperature sensor 72 for detecting the temperature of the hydraulic oil is provided. The detection value of the oil temperature sensor 72 is sent to the ECU 50.

  The hydraulic pressure supply device 60 of this embodiment is for sealing the hydraulic oil in an oil pump 75 that is driven by a motor 77 for supplying hydraulic oil to the piston chamber 32 and an oil passage 80 that leads from the oil pump 75 to the piston chamber 32. Check valve (hydraulic oil sealing valve) 39, a solenoid valve 78 for opening and closing an oil passage 80 between the check valve 76 and the piston chamber 32, and an accumulator 83 communicating with the piston chamber 32. The hydraulic circuit 30 and an ECU 50 that controls the driving of the oil pump 75 by the motor 77 and the opening and closing of the solenoid valve 78 to supply a desired hydraulic pressure to the piston chamber 32. When pressurizing the piston chamber 32 in order to engage the clutch 20, the solenoid valve 78 is closed and the oil pump 75 is driven to feed the hydraulic oil into the sealed oil passage 80 and pressurize it. Thereby, it controls so that the piston chamber 32 becomes target hydraulic pressure. On the other hand, when the pressure in the piston chamber 32 is reduced in order to release the engagement of the clutch 20, the drive of the oil pump 75 is prohibited (stopped) and the solenoid valve 78 is opened so that the hydraulic oil in the oil passage 80 is discharged. Discharge into the oil tank 71. As a result, the piston chamber 32 is controlled to reach the target hydraulic pressure.

  FIG. 3 is a side sectional view showing the driving force transmission mechanism 2 of the vehicle 1 including the clutch 20. FIG. 4 is a partially enlarged cross-sectional view showing a detailed configuration of the clutch 20. In the following description, as indicated by arrows in FIG. 3, the left-right direction in FIG. 3, which is the front-rear direction of the vehicle 1 on which the driving force transmission mechanism 2 is mounted, is referred to as front and rear. Further, the axial direction refers to the axial direction of first and second rotating shafts 41 and 42 to be described later.

  A driving force transmission mechanism 2 shown in FIG. 3 includes a first rotating shaft 41 connected to the propeller shaft 7 (see FIG. 1), a second rotating shaft 42 arranged coaxially with the first rotating shaft 41, A clutch 20 for detachably connecting the first rotating shaft 41 and the second rotating shaft 42 is provided. Further, a final reduction drive pinion 44 integrally formed at the rear end of the second rotating shaft 42, a final reduction driven gear 45 meshing with the final reduction drive pinion 44, and a rear wheel disposed in the final reduction driven gear 45 The differential mechanism 46 is provided. The driving force transmission mechanism 2 includes a front casing 51 that houses the first rotating shaft 41, a middle casing 52 that is connected to the rear end of the front casing 51 and houses the clutch 20, a rear end of the middle casing 52, and a later description. And a rear casing 53 that is connected to the rear end of the piston housing 31 and accommodates the second rotating shaft 42.

  As shown in FIG. 4, the clutch 20 includes a substantially cylindrical clutch housing 21 coupled to the rear end of the first rotation shaft 41 and a spline connection to the front end of the second rotation shaft 42 on the inner peripheral side of the clutch housing 21. And a pressure plate 23a and a friction plate 23b, which are friction materials obtained by alternately laminating a plurality of clutch hubs 22 along the axial direction in the clutch housing 21. The outer peripheral end of the pressure plate 23 a is locked to the clutch housing 21, and the inner peripheral end of the friction plate 23 b is locked to the clutch hub 22. The plurality of pressure plates 23a and the friction plates 23b constitute a friction engagement portion 23. An end plate 24 is installed at the rear end in the stacking direction of the pressure plate 23a and the friction plate 23b.

  The clutch housing 21 has an opening 21a at an end on the rear side in the axial direction, and an end cap 25 is attached to the opening 21a. The end cap 25 is a substantially circular plate-like member, and the plurality of pressure plates 23 a and the friction plates 23 b constituting the friction engagement portion 23 are locked in the clutch housing 21 by the end cap 25.

  The pressure piston 26 installed on the rear side of the end cap 25 is a substantially circular plate-like member having a substantially circular through hole at the center. The pressure piston 26 is supported by an inlay on the outer diameter side of the flange portion 25 c of the end cap 25. Thereby, the pressure piston 26 is engaged with the end cap 25 in a state of rotating integrally with the end cap 25 and being relatively movable only in the axial direction with respect to the end cap 25.

  Further, on the surface of the pressure piston 26 on the side of the clutch housing 21, a protruding pressing portion 26 d that protrudes in the axial direction is formed. On the other hand, a through hole 25d is formed at a position corresponding to the pressing portion 26d in the end cap 25. In addition, although illustration is abbreviate | omitted, the some press part 26d and 25 d of through-holes are provided in the circumferential direction of the pressure piston 26 and the end cap 25 at equal intervals. As shown in FIG. 4, the pressing portion 26 d of the pressure piston 26 passes through the through hole 25 d of the end cap 25 and protrudes into the clutch housing 21, and the tip of the pressing portion 26 d comes into contact with the end plate 24. It is like that.

  On the other hand, a piston housing 31 is installed behind the end cap 25 and the pressure piston 26. The piston housing 31 is provided with a substantially circular opening 31a at the center thereof, and a cylindrical flange 31c protruding forward in the axial direction is provided at the front end of the opening 31a. Is formed. A cylinder piston 33 is installed on the outer diameter side of the flange portion 31c. A thrust needle bearing 29 is interposed between the cylinder piston 33 and the pressure piston 26, and the cylinder piston 33 and the pressure piston 26 are capable of relative rotation and movable integrally in the axial direction. In the gap between the piston housing 31 and the cylinder piston 33, a piston chamber (oil chamber) 32 for generating hydraulic pressure by hydraulic oil is defined. The cylinder piston 33 is installed so as to be movable relative to the piston housing 31 along the axial direction. A seal member 34 for sealing the piston chamber 32 is installed between the outer periphery of the cylinder piston 33 and the piston housing 31. Has been.

  Further, an oil passage 80 through which hydraulic oil from the oil pump 35 (see FIG. 1) is introduced communicates with the piston chamber 32 of the piston housing 31. The oil passage 80 is provided with a hydraulic sensor 79 for detecting the hydraulic pressure of the hydraulic oil.

  With the above configuration, when hydraulic oil is introduced into the piston chamber 32 in the piston housing 31 by the operation of the oil pump 75, the cylinder piston 33 receiving pressure from the piston chamber 32 moves forward along the axial direction. The pressure piston 26 moves in the same direction. As a result, the end plate 24 at the end of the friction engagement portion 23 is pressed by the pressing portion 26d of the pressure piston 26, and the pressure plate 23a and the friction plate 23b are pressed against each other so that the clutch 20 is fastened. It has become.

  5A and 5B are diagrams showing the configuration of the piston chamber 32 and its surroundings. FIG. 5A is a side view of the piston chamber 32 viewed from the axial direction (a cross-sectional view taken along arrow P in FIG. 3), and FIG. It is a figure which shows the AA-A 'cross section of (a). FIG. 6 is a view showing the external configuration of the piston chamber 32 and its surroundings, and FIG. 6A is a side view of the piston housing 31 viewed from the axial direction (a view corresponding to the arrow Q in FIG. 3). (B) is a figure which shows the X arrow view of (a). In FIG. 5A, for convenience of explanation, a portion corresponding to the cross section of the piston chamber 32 is hatched. As shown in these drawings, in the hydraulic circuit 30 provided in the hydraulic pressure supply device 60 of the present embodiment, a small accumulator 83 is installed on the back side of the piston chamber 32 (on the side opposite to the cylinder piston 33 in the axial direction). .

  The piston chamber 32 is disposed on the outer diameter side of the second rotating shaft 42, and is a chamber having a substantially circular cross-sectional shape when viewed from the axial direction. The piston chamber 32 is provided with a first opening 85 connected to a first oil passage 80 leading to an oil pump 75 and a second opening 86 connected to a second oil passage 81 leading to an accumulator 83. ing. As shown in FIGS. 5A and 6A, the first opening 85 and the second opening 86 are the center in the circular cross section of the piston chamber 32 (the axis of the second rotating shaft 42). By being arranged on both sides of the M, they are arranged so as to be located at a maximum distance in the cross section. The first opening 85 and the second opening 86 may be installed at substantially opposite positions (positions separated from the center M of the piston chamber 32 by approximately 180 °) across the center M of the piston chamber 32. desirable.

  Thus, in the present embodiment, in the cross section of the piston chamber 32, the second oil passage 81 leading to the accumulator 83 is connected to the first opening 85 connected to the first oil passage 80 leading to the oil pump 75. By arranging the connected second openings 86 to be as far away as possible, the effect of suppressing hydraulic pressure fluctuations by the accumulator 83 can be obtained to the maximum. As a result, the hydraulic pressure change in the piston chamber 32 is less affected by the dynamic pressure due to the drive of the oil pump 75, and the stability of the hydraulic control of the piston chamber 32 is obtained.

  FIG. 7 is a graph showing a change in hydraulic pressure when the piston chamber 32 is pressurized depending on the installation position of the accumulator 83. In the graph of the figure, the horizontal axis is the elapsed time, and the vertical axis is the hydraulic pressure of the piston chamber 32. The change indicated by the solid line is the target hydraulic pressure of the piston chamber 32, and the change indicated by the dotted line is the first opening 85 and the second opening 86 provided in the piston chamber 32 in the hydraulic pressure supply device 60 of the present embodiment. In the cross section of the piston chamber 32, and the change indicated by the alternate long and short dash line is a change in the hydraulic pressure supply device of the conventional configuration in which the first opening and the second opening are connected to the piston. This is a change in hydraulic pressure when placed close to each other in the cross section of the chamber.

  As shown in the graph of FIG. 7, in the hydraulic circuit 30 having the enclosed oil passage 80 as in the present embodiment, the first opening 85 and the accumulator 83 communicating with the oil pump 75 within the cross section of the piston chamber 32. When the second opening 86 that communicates with the second opening 86 is arranged so as to be maximally separated (change indicated by a dotted line), the change when the first opening 85 and the second opening 86 are arranged close to each other (one point) Compared with the change indicated by the chain line), the hydraulic pressure in the piston chamber 32 is less affected by the dynamic pressure due to the drive of the oil pump 75, so the deviation ΔP of the hydraulic pressure with respect to the target hydraulic pressure (change shown in practice) is a smaller value. It becomes possible to suppress to.

  As described above, in the hydraulic pressure supply device 60 according to the present embodiment, the first opening 85 connected to the first oil passage 80 connected to the oil pump 75 and the second oil passage 81 connected to the accumulator 83 are connected. Since the second opening 86 is disposed on each of both sides of the center M in the cross section of the piston chamber 32, the first opening 85 and the second opening 86 are mutually within the cross section of the piston chamber 32. It is arranged to be separated as much as possible. Thereby, compared with the case where the 1st opening part 85 and the 2nd opening part 86 are arrange | positioned in the position close | similar to each other in the cross section of the piston chamber 32, the oil_pressure | hydraulic of the piston pump 32 and the solenoid of the oil pump 75 are driven. Since it becomes difficult to be affected by the dynamic pressure due to the opening and closing of the valve 78, the deviation of the hydraulic pressure from the target hydraulic pressure can be kept small. Therefore, the effect of suppressing the hydraulic pressure fluctuation by the accumulator 83 can be maximized.

  Further, since the hydraulic pressure fluctuation suppressing action by the accumulator 83 can be obtained to the maximum, the accumulator 83 installed in the hydraulic circuit 30 can be downsized. Therefore, it is possible to install a small accumulator 83 on the back side of the piston chamber 32 as in this embodiment. As a result, the hydraulic pressure supply device 60 can be reduced in size and weight.

  Further, in the hydraulic pressure supply device 60 of the present embodiment, the first opening 85 and the second opening 86 are disposed so as to be maximally separated from each other within the cross section of the piston chamber 32, so that the piston chamber 32. Is less susceptible to the dynamic pressure due to the drive of the oil pump 75, so that the oil pump 75 is driven and the solenoid valve 78 is opened and closed with the hydraulic oil sealed in the first oil passage 80 as in this embodiment. Even when the hydraulic pressure is controlled by performing the above, the deviation of the hydraulic pressure from the target hydraulic pressure can be suppressed small. Thereby, it is possible to perform quick and accurate hydraulic control. Therefore, the accuracy of hydraulic control by the hydraulic supply device 60 can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible.

DESCRIPTION OF SYMBOLS 1 Four-wheel drive vehicle 2 Driving force transmission mechanism 10 Driving force transmission path 20 Front / rear torque distribution clutch (clutch)
30 Hydraulic circuit 31 Piston housing 32 Piston chamber 50 4WD • ECU (control means)
60 Hydraulic supply device 75 Oil pump 76 Check valve 77 Motor 78 Solenoid valve 79 Hydraulic sensor 80 First oil passage 81 Second oil passage 83 Accumulator 85 First opening 86 Second opening

Claims (1)

A driving force transmission path for transmitting the driving force from the driving source to the main driving wheel and the sub driving wheel;
In a four-wheel drive vehicle comprising: a drive force distribution device disposed between the drive source and the auxiliary drive wheel in the drive force transmission path;
The driving force distribution device includes a friction engagement element having a plurality of laminated friction materials and a piston chamber that generates hydraulic pressure for driving a piston for pressing and engaging the friction materials in the lamination direction. Has been
In the hydraulic pressure supply device of the driving force distribution device provided with a hydraulic circuit composed of an oil pump for supplying hydraulic oil to the piston chamber and an accumulator for storing the hydraulic pressure of the piston chamber,
The piston chamber is a chamber that is disposed on the outer diameter side of the rotating shaft and has a substantially circular cross section viewed from the axial direction,
The piston chamber is provided with a first opening connected to a first oil passage leading to the oil pump, and a second opening connected to a second oil passage leading to the accumulator,
A hydraulic oil sealing valve for sealing the first oil path and sealing the hydraulic oil in the first oil path;
An on-off valve for opening and closing the first oil passage sealed with the hydraulic oil enclosure valve;
Control means for controlling oil pressure supplied to the piston chamber by controlling driving of the oil pump by a motor and opening / closing of the on-off valve;
When pressurizing the piston chamber, the control means closes the on-off valve and drives the oil pump with the motor to control the piston chamber to a target hydraulic pressure,
When depressurizing the piston chamber, the oil pump is prohibited from being driven by the motor and the on-off valve is opened to control the piston chamber to have a target hydraulic pressure.
The first opening and the second opening are arranged on both sides of the piston chamber in the cross section, so that the first opening and the second opening are mutually connected to the piston. A hydraulic pressure supply device for a driving force distribution device, wherein the hydraulic pressure supply device is arranged so as to be maximally separated within the cross section of the chamber.

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