JPH09196144A - Differential device - Google Patents

Abstract

(57) An object of the present invention is to prevent a tight corner break phenomenon with a slight loss of differential limiting force and facilitate assembly. SOLUTION: A differential gear mechanism 45 for differentially distributing the rotation of the differential case 3, a friction clutch 49 for limiting the differential of the mechanism 45, a pump 55 driven by the differential rotation of the mechanism 45, and its An actuator 53 that presses the clutch 49 via the piston 57 by receiving the discharge pressure, and an actuator.
An orifice 91 that allows the operating pressure of the actuator 53 to escape to the outside, an orifice 93 that is provided in the piston 57 and is closed when the clutch 49 is pressed, and has an opening area larger than the orifice 91, and an actuator while the mechanism 45 differentially rotates at a low speed. −
And a spring 95 that pushes the piston 57 back to the disengagement side of the clutch 49 against the pressing force of the clutch 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential device used for a vehicle.

[0002]

2. Description of the Related Art FIG. 8 is disclosed in JP-A-61-282645.
Such a differential device 201 is described.

[0003] The differential device 201 includes a pinion shaft 205 fixed to a differential case 203,
A differential mechanism 213 including a pinion gear 207 rotatably supported on a pinion shaft 205 and side gears 209 and 211 meshing with the pinion gear 207, a multi-disc clutch 215 for limiting a differential, and a multi-disc clutch 215.
It includes a hydraulic actuator 217 for fastening the gear, a gear pump 219, and a spring 221. Side gear 20
9 and 211 are spline-connected to the axles 223 and 225, respectively.

The gear pump 219 is driven by the differential rotation of the differential mechanism 213, and gives a hydraulic pressure to the hydraulic actuator 217. The hydraulic actuator 217 is the piston 22.
The multi-plate clutch 215 is pressed and fastened via 7 to limit the differential of the differential mechanism 213.

Further, the spring 221 is the hydraulic actuator 2
It acts in the direction opposite to the pressing force of 17, and urges the piston 227 in the disengagement direction of the multi-plate clutch 215.

[0006]

When the differential limiting force of the differential device is strong, for example, when the vehicle makes a sharp turn at a low speed, such as when putting in a garage, the tight corner blur due to the difference in turning radius between the drive wheels. A phenomenon occurs, which causes increased wear of the drive wheels that slip forcibly and reduced engine fuel consumption. Further, if the tire diameters differ during high-speed running, differential rotation occurs, which adversely affects fuel economy.

FIG. 9 is a performance diagram showing a change in the differential rotation speed of the differential device 201 and the differential limiting torque T (piston thrust force) generated at that time. A two-dot chain line graph 229 shows the spring 221. The characteristics when not used, and the solid line graph 231 is the characteristics when the spring 221 is used.

As shown in these graphs, the differential limiting torque Ts is generated without the spring 221 when the differential rotation speed is A1 when entering the garage, but when the spring 221 is used, the differential limiting torque is reduced. It becomes zero and the tight corner break phenomenon is prevented.

However, when the differential speed increases to A2, a large differential limiting torque Tn can be obtained without using the spring 221, but the use of the spring 221 weakens the pressing force of the hydraulic actuator 217. Differential limiting torque is T
n-Ts.

Thus, the spring 221 causes the piston 227 to move.
In a configuration in which the spring is simply pushed back, the spring 221 having a large spring force is provided in order to sufficiently prevent the tight corner break phenomenon.
Therefore, the strong spring 221 causes an excessive loss of the differential limiting force, and the strong spring force makes the assembling work difficult.

Further, in the structure of the differential device 201, there is little escape of oil from the hydraulic actuator 217 and oil is not drained well. Therefore, the differential limiting force disappears when the differential is stopped. Poor response.

Therefore, the present invention is a differential device in which a built-in pump is driven by differential rotation and a friction clutch for differential limiting is engaged by the oil pressure thereof, and a tight clutch is provided with a slight loss of differential limiting force. An object of the present invention is to provide a differential device which can sufficiently prevent the phenomenon of noise breakage, is easy to assemble, and has a good fall response of the differential limiting force when the differential is stopped.

[0013]

According to another aspect of the present invention, there is provided a differential device in which any one of three members, that is, a differential case and a pair of side gears, is rotationally driven by a driving force of an engine, and the remaining three members are connected via a pinion gear. Differential gear mechanism that outputs from two members, a friction clutch that limits the differential of the differential gear mechanism, a pump that is driven by differential rotation of the differential gear mechanism, and a piston that receives the discharge pressure of the pump. An actuator that presses and engages the friction clutch via a first orifice, a first orifice that releases the operating pressure of the actuator to the outside, and a piston provided on the piston that is closed by the friction clutch when the piston presses the friction clutch. When the discharge pressure of the pump is lower than the specified value due to the differential rotation of the other orifices and the differential gear mechanism at a low speed, the piecing force is applied against the pressing force of the actuator. Characterized in that a spring which pushes back the on to unfastening side of the friction clutch.

The pump is driven by the differential rotation of the differential gear mechanism, operates the actuator, and engages the friction clutch to limit the differential of the differential gear mechanism.

The actuator is provided with a first orifice for releasing the working pressure to the outside. Also, the piston is provided with one or more other orifices,
These are closed by the friction clutch when the piston pushes it. When the differential gear mechanism differentially rotates at a low speed and the discharge pressure of the pump becomes lower than a predetermined value, the piston is pushed back by the spring, the friction clutch is opened, and other orifices are opened.

Thus, at the time of rapid rotation at a low speed where the tight corner break phenomenon is likely to occur, the other orifices are opened, and all the orifices including the first orifice greatly reduce the working pressure of the actuator. Therefore, even if a spring having a weak spring force is used, the differential limitation is stopped and the tight corner break phenomenon is prevented.

When the differential rotation speed increases and a large differential limiting force is required, the discharge pressure of the pump exceeds a predetermined value due to the increase in the differential rotation speed, and other orifices are closed against the spring force. As a result, the operating pressure of the actuator is restored and a large differential limiting force is obtained.

As described above, when a large differential limiting force is required, a sufficient differential limiting force is obtained, and when it is desired to greatly reduce the differential limiting force, the differential limiting force is reduced at once.
The tight corner brake phenomenon is suppressed, and the increase in wear of the drive wheels and the decrease in engine fuel consumption are prevented.

In this way, since a weak spring can be used, the loss of the differential limiting force due to the spring force is greatly reduced and the assembling work is facilitated as compared with the conventional example.

In addition to this, the operating pressure of the actuator is released from the first orifice provided in the actuator during high speed differential rotation, and from all the orifices during low speed differential rotation. The differential limiting force disappears when the differential is stopped. The falling response of the differential limiting force is extremely good.

Further, the friction clutch is sufficiently lubricated by the oil discharged from each orifice, and the durability is greatly improved.

A differential device according to a second aspect is the differential device according to the first aspect, in which the opening area of the other orifice is made larger than the opening area of the first orifice, and like the differential apparatus of the first aspect, Since a weak spring can be used, the loss of the differential limiting force due to the spring force is significantly reduced, and a sufficient differential limiting force can be obtained when the differential limiting force is required. The phenomenon can be effectively prevented, the assembling work is easy, and the falling response of the differential limiting force is extremely good.

In addition to this, since the opening areas of the other orifices are made larger than the opening areas of the first orifices, the opening areas of all the orifices at the time of low speed differential rotation become wider, and the spring force can be further weakened. The loss of the differential limiting force due to the spring force can be greatly reduced, and the workability of assembly can be further improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. This embodiment has the features of claims 1 and 2, and FIG. 1 shows a differential device 1 of this embodiment. In addition, members and the like without reference numerals are not shown.

As shown in FIG. 1, the differential case 3 of the differential device 1 is constructed by fixing a casing body 5 and a cover 7 with bolts 9. The differential case 3 is arranged inside the differential carrier, and an oil reservoir is formed in the differential carrier.

The boss portions 11 and 13 of the differential case 3 are supported by the differential carrier via bearings. Def-key
A ring gear is fixed to the space 3 with bolts, and the ring gear meshes with the drive gear of the drive force transmission system. Thus, the differential case 3 is rotationally driven by the driving force of the engine via this driving force transmission system.

Inside the differential casing 3, a plurality of pinion shafts 17 are radially arranged around the boss portion 15, and the chamfered portion 19 formed on the outer end portion of each pinion shaft 17 is a differential casing. -Engage in the groove 21 of the sleeve 3,
It is connected so that it can move in the axial direction. A pinion gear 23 is rotatably supported on each pinion shaft 17.

Inside the differential case 3, a pair of output side gears 25 and 27 are arranged. These side gears 25 and 27 are integrally formed with the respective boss portions 29 and 31, and the side gears 25 and 27 are connected to the pinion gear 2 respectively.
It is supported from the outside in the radial direction by meshing with 3. A spherical washer 33 is arranged between the pinion gear 23 and the differential case 3, and bears the centrifugal force of the pinion gear 23 and the meshing reaction force that the pinion gear 23 receives by meshing with the side gears 25 and 27. .

The boss portion 29 of the side gear 25 is rotatably supported by the support portion 35 of the differential case 3 and the inner periphery of a pump housing 37 described later, and the boss portion 31 of the side gear 27 is the boss portion 15 of the pinion shaft 17. It is rotatably supported by the inner periphery and the support portion 39 of the differential case 3.
A washer 41 is arranged between the side gear 25 and the pump housing 37, and the side gear 27 and the differential gear are arranged.
A washer 43 is arranged between the shoe 3 and the shoe 3. The side gears 25 and 27 are spline-connected to the output shaft via the boss portions 29 and 31, respectively.

Thus, the bevel gear type differential gear mechanism 4
5 are configured. The pinion shaft 17, the pinion gear 23, and the side gears 25, 27 of the differential gear mechanism 45.
Are axially movable on the groove 21.

The driving force of the engine for rotating the differential case 3 is distributed from the pinion shaft 17 to the side gears 25 and 27 via the pinion gear 23 and transmitted to the wheel side via each output shaft. Further, for example, when a driving resistance difference is generated between the wheels during traveling on a rough road, the driving force of the engine is differentially distributed to each wheel side by the rotation of each pinion gear 23.

The top 47 of the side gear 25 and the differential case 3
A multi-plate clutch 49 (friction clutch) is disposed between and. A back ring 51 is arranged between the multi-plate clutch 49 and the differential case 3, and bears a pressing force from the multi-plate clutch 49 between the multi-plate clutch 49 and the differential case 3. A hydraulic actuator 53 (actuator) is arranged on the left side of the multi-plate clutch 49, and an external gear pump 55 (pump) is arranged on the left side of the hydraulic actuator 53.

The piston 57 of the hydraulic actuator 53 is axially movable between the differential case 3 and the pump housing 37 via seals 59 and 61, respectively. The cylinder 63 of the hydraulic actuator 53 is formed between the piston 57, the pump housing 37 and the differential case 3.

The gear pump 55 has a pump housing 37.
And a sun gear 65, a plurality of pinion gears 67, check valve mechanisms 69, 71 and the like.

The outer circumference of the pump housing 37 is press-fitted into the differential case 3 and further fixed to the differential case 3 with bolts 73. The pump housing 37 has a large-diameter storage hole concentric with the sun gear 65 and a small-diameter storage hole arranged on the outer periphery of the sun gear 65. The storage holes communicate with each other to form a pump chamber.

The sun gear 65 is slidably and rotatably housed in a large-diameter housing hole, and its inner circumference is spline-connected to the outer circumference of the boss portion 29 of the side gear 25. Each pinion gear 67 is slidably and rotatably housed in a small-diameter housing hole. Each pinion gear 67 is supported on a pinion shaft 75, and both ends of the pinion shaft 75 are supported by the differential case 3 and the pump housing 37.

The sun gear 65 and each pinion gear 67 mesh with each other in the pump chamber to form the gear pump 55.

The cover 7 is provided with a suction port 77 through which the gear pump 55 sucks oil and another suction port. The pump housing 37 has a gear pump 55.
Is provided with a discharge port 79 for discharging oil to the cylinder 63 of the hydraulic actuator 53 and another discharge port.

The check valve mechanism 69 includes a valve seat 81,
Disc-shaped intake valve body 8 in which the valve seat 81 is arranged to be openable and closable
And 3. A plate ring 85 is attached to the cover 7 to prevent the valve body 83 from falling off.

The valve seat 81 faces the gear pump 55 side, and the check valve mechanism 69 has the valve seat 81 formed by the valve body 81.
By opening and closing 3, the oil is sucked into the gear pump 55 from the suction port on the opening side and the gear pump 55
To shut off the return oil from the intake port to the suction port on the block side.

The check valve mechanism 71 has a valve seat 8
7 and a disc-shaped discharge side valve body 89 in which the valve seat 87 is openably and closably arranged. These valve bodies 89 are prevented from falling off by a plate ring mounted in the pump housing 37. There is.

The valve seat 87 faces the hydraulic actuator 53 side, and the check valve mechanism 71 opens and closes the valve seat 87 by the valve body 89, so that the check valve mechanism 71 opens the valve seat 87 through the discharge port on the open side. The oil is discharged to the hydraulic actuator 53 and the return oil from the hydraulic actuator 53 and the discharge port on the closed side is shut off.

When differential rotation occurs in the differential gear mechanism 45,
The pinion gear 67 on the side of the pump housing 37 and the sun gear 65 on the side of the side gear 25, which are fixed to the differential case 3, rotate relative to each other, and the gear pump 55 is driven.

As shown in FIGS. 2 and 3, a hydraulic actuator.
The piston 57 of the rotor 53 has a first orifice 91 and a second orifice 91.
(Other) orifice 93 is provided. As shown in FIG. 2, two of these are provided at equal intervals in the circumferential direction, the first orifice 91 is provided inside in the radial direction, and the second orifice 93 is provided outside in the radial direction.

The opening area of the second orifice 93 is larger than that of the first orifice 91, and
As shown in FIGS. 1, 4, and 5, the first orifice 91 is arranged at a position not facing the multi-plate clutch 49, and the second orifice 93 is arranged at a position facing the multi-plate clutch 49.

A coil spring 95 (spring) is arranged between the side gear 25 and the piston 57, and the piston 5
7 is urged in the direction of releasing the engagement of the multi-plate clutch 49.

An oil pocket 97 is attached to the side surface of the cover 7. The oil pocket 97 includes a partition member 99 and a seal member 10 which is lined with the partition member 99 to be liquid-tight.
1 and a ring 103, an oil chamber 105 is formed between the cover 1 and the ring 7. Oil pocket 97 is a cover
It is slidable and rotatable with respect to 7, and the oil chamber 105 is connected to the oil reservoir of the differential carrier via an oil pipe.

When the gear pump 55 is operated, the oil in the oil sump is sucked up into the oil chamber 105 through the oil pipe, further pressurized by the gear pump 55, and given to the cylinder 63 of the hydraulic actuator 53.

When oil pressure is applied to the cylinder 63, the hydraulic actuator 53 presses and engages the multi-plate clutch 49 via the piston 57, and the frictional resistance of the multi-plate clutch 49 and the pump work of the gear pump 55 cause it. The differential of the differential gear mechanism 45 is limited. Since the frictional resistance of the multi-plate clutch 49 and the pump work of the gear pump 55 increase as the differential rotation speed increases, a differential limiting function sensitive to the differential rotation speed can be obtained.

When the differential rotation speed becomes lower than a certain value, the check valve mechanisms 69 and 71 close the respective ports to stop the pump function of the gear pump 55 and release the differential limitation.

The differential casing 3 is provided with openings 107 and 109. From these openings 107 and 109, the oil in the oil sump and the oil splashed up by the rotation of the ring gear and bounced off the inner wall of the differential carrier are deflected. 3, the gears of the differential gear mechanism 45 and the multi-plate clutch 49 are lubricated to enhance durability.

When oil pressure is applied to the cylinder-63, a proper amount of oil is supplied to the orifice 9 of the piston 57.
The oil discharged from Nos. 1 and 93 lubricates the multi-plate clutch 49, the meshing parts of the gears, the sliding parts between the pinion gear 23 and the pinion shaft 17 and the spherical washer 33, and the centrifugal forces from the openings 107 and 109. Is discharged to the outside and returns to the oil reservoir of the differential carrier.

4 and 5 show the position of the piston 57 and the open and closed states of the orifice 93 when the differential gear mechanism 45 is differentially rotating at high speed and differentially rotating at low speed, respectively. Is shown.

When the differential gear mechanism 45 differentially rotates at a low speed and the discharge pressure of the gear pump 55 is lower than a predetermined value, the coil spring 95 resists the pressing force of the actuator 53 and causes the piston 57 to move the multi-plate clutch 49. Push back to the side to release the connection to eliminate the differential limiting force.

FIG. 5 shows a case where the thrust force of the piston 57 does not exceed the force of the coil spring 95 as described above, and in this state, both the orifices 91 and 93 are opened. Therefore, the oil flowing out from both orifices 91 and 93 causes a large pressure leak, and the discharge pressure of the gear pump 55 decreases, so that the pressing force of the actuator 53 becomes smaller than the spring force of the coil spring 95. (State 2) When the differential gear mechanism 45 differentially rotates at high speed and the discharge pressure of the gear pump 55 exceeds a predetermined value, the coil spring 95 is bent and the piston 57 presses the multi-plate clutch 49. Tighten and generate differential limiting force.

FIGS. 1 and 4 show the case where the thrust force of the piston 57 exceeds the force of the coil spring 95 as described above. In this state, the piston 57 is pressed against the multi-plate clutch 49 and the orifice 93 is opened. It is closed and only the orifice 91 is opened. In this way, the pressure leakage from the piston 57 is reduced and the discharge pressure of the gear pump 55 is increased, so that the pressing force of the actuator 53 becomes larger than the spring force of the coil spring 95. (State 1) FIG. 6 is a performance diagram showing changes in the differential rotation speed of the differential device 1 and the differential limiting torque T (piston thrust force) generated at that time. A two-dot chain line graph 111 is the characteristic when the coil spring 95 is not used, and corresponds to the graph 229 in FIG. 9. Further, the solid line graph 113 is the characteristic corresponding to the state 1 in FIG. 4, and the two-dot chain line graph 1
Reference numeral 15 is a characteristic corresponding to the state 2 in FIG. Where A
1 is a differential rotation speed at which the discharge pressure of the hydraulic actuator 53 becomes a predetermined value, and the differential limiting characteristic shifts from one of the states 1 and 2 to the other.

Therefore, while the vehicle makes a sharp turn at a low speed such as when entering the garage and the differential gear mechanism 45 is differentially rotating at a differential rotation speed of A1 or less, as in the state 2 described above, a large number of rotations are generated. The plate clutch 49 is released, and the differential limiting torque T becomes zero as indicated by an arrow 117 in FIG. In this way, the tight corner break phenomenon is prevented, and the wear of the drive wheels and the deterioration of engine fuel consumption are prevented.

When the differential rotation speed exceeds A1, the differential limiting characteristic shifts to the state 1, and the differential limiting torque T changes on the graph 113 according to the change in the differential rotational speed. At this time, as described above, a large differential limiting force is obtained by reducing the pressure leakage from the piston 57 due to the closing of the orifice 93 and increasing the discharge pressure of the gear pump 55.

As described above, since the piston 57 is provided with the orifice 93 and the orifice 93 is opened during the low speed differential rotation to reduce the pressing force of the actuator 53, the spring force of the coil spring 95 is reduced. Can be made that much weaker. Therefore, as shown in FIG. 6, when the differential rotation speed is reduced to A1, conventionally, a strong spring force equivalent to Ts was required, whereas the differential device 1
Then, a weak spring force equivalent to Ts' is enough.

Further, when the differential rotation speed rises to A2, the differential limiting torque has conventionally decreased to Tn-Ts due to the strong spring force, whereas in the differential device 1, the difference in Tn-Ts' which is larger than that has decreased. Dynamic limiting torque can be obtained.
As described above, the loss of the differential limiting force due to the spring force is significantly reduced as compared with the conventional example.

In this way, the differential limiting is stopped by the coil spring 95 at the time of rapid rotation at a low speed where the tight-corner-break phenomenon is likely to occur, and the tight-corner-break phenomenon is effectively prevented. At the same time, when the differential rotation speed increases and a large differential limiting force is required, the orifice 93 is closed against the coil spring 95, the operating pressure of the actuator 53 is restored, and a sufficient differential limiting force is provided. can get.

Further, since the coil spring 95 having a weak spring force can be used, the assembling work becomes easier.

In addition to this, the operating pressure of the actuator 53 is released from the first orifice 91 during the high speed differential rotation, and from both orifices 91 and 93 during the low speed differential rotation, so that the differential pressure is generated. The falling response of the differential limiting force when stopped is extremely good.

Further, the multi-plate clutch 49 has each orifice 9
It is sufficiently lubricated by the oil discharged from Nos. 1 and 93, and the durability is greatly improved.

A vehicle using the differential device 1 is
Its large speed-sensitive differential limiting function improves maneuverability and stability, and the driving performance is sent to the other driving wheel when one driving wheel spins on a bad road. The running performance is greatly improved.

In addition to this, by making the opening area of the second orifice 93 larger than the opening area of the first orifice 91, both orifices 91, 9 during low speed differential rotation are provided.
Since the opening area of 3 becomes wider and the spring force of the coil spring 95 can be further weakened accordingly, the loss (Ts ′) of the differential limiting torque due to the spring force is greatly reduced.

In the present invention, the method of making the opening area of the other orifices larger than the opening area of the first orifice is such that the opening area of the second orifice 93 is larger than that of the first orifice 91 as in the differential device 1. It is not limited to the method of enlarging.

FIG. 7 shows a piston 119 used in the second embodiment of the present invention. The opening areas of the first and second (other) orifices 121 and 123 are the same, and two first orifices 121 are provided. By providing four second orifices 123, the opening areas of the other orifices are made larger than the opening areas of the first orifices.

Therefore, similarly to the differential device 1, the operating pressure of the actuator at the time of low speed rotation is greatly reduced, and the spring can be weakened accordingly, so that the loss (Ts') of the differential limiting torque due to the spring force is greatly reduced. Along with
Assembly work becomes easy.

As described above, the number and opening area of other orifices that are closed when the friction clutch is engaged may be arbitrarily selected. Further, other orifices may be combined with orifices having different opening areas.

The first and second embodiments described above show the differential gear mechanism 45 in which the driving force of the engine is input to the differential case 3 and output from the pair of side gears 25 and 27 via the pinion gear 23. However, unlike this, for example, a differential gear mechanism in which the driving force of the engine is input to one side gear and is output from the differential case and the other side gear may be used.

Further, the differential gear mechanism is not limited to the bevel gear type, and for example, friction resistance between gears and gear and differential gear can be used.
A helical gear type differential gear mechanism that obtains a torque-sensitive differential limiting function by using the friction resistance with the gear, or a torque-sensitive differential limiting function that uses the tooth surface friction resistance of the worm gear. It may be a differential gear mechanism or the like. By using such a differential gear mechanism, it is possible to obtain a differential device having not only the torque-sensitive differential limiting function but also the speed-sensitive differential limiting function by the friction clutch and the pump.

The clutch for limiting the differential is not limited to the multi-plate clutch, but may be another friction clutch such as a cone clutch.

The pump may be other than the gear pump,
The gear pump may be of the inscribed type.

The differential apparatus according to the present invention includes a front differential (a differential apparatus arranged on the axle of the front wheels), a rear differential (a differential apparatus arranged on the axle of the rear wheels), and a center differential (the driving force of the engine is applied to the front wheels). And a differential device for distributing to the rear wheels).

[0076]

As described above, in the differential device according to the first aspect of the present invention, the actuator is provided with the first orifice for releasing the working pressure to the outside, and when the piston is pressed by the friction clutch, it is closed by the friction clutch. An orifice is provided, and a spring for returning the piston to the disengaged side of the friction clutch is arranged against the pressing force of the actuator while the differential gear mechanism differentially rotates at low speed.

Therefore, at the time of rapid rotation at a low speed where the tight corner break phenomenon is likely to occur, the other orifices are opened, the operating pressure of the actuator is greatly reduced by all the orifices, and the differential pressure is generated by the spring. The restriction stops and the tight corner break phenomenon is prevented.

When the differential rotation speed increases and a large differential limiting force is required, other orifices are closed against the spring force, and the operating pressure of the actuator is restored, so that a large differential limiting force is obtained. Is obtained.

Since the other orifices can be opened and closed in this way, a spring having a weak spring force can be used, and the loss of the differential limiting force due to the spring force is greatly reduced as compared with the conventional example. Assembly work becomes easy.

Furthermore, the operating pressure of the actuator is released from the first orifice during high-speed differential rotation, and from all orifices during low-speed differential rotation, so the differential limiting force when the differential is stopped. The falling response is extremely good.

Further, the friction clutch is sufficiently lubricated by the oil discharged from each orifice, and the durability is greatly improved.

The differential device according to claim 2 has the same effect as that of the differential device according to claim 1, and the opening area of the other orifice is made larger than the opening area of the first orifice so that the differential rotation speed is low. Since the opening area of all the orifices is widened and the spring force can be further weakened, the loss of the differential limiting force due to the spring force is significantly reduced, and the workability of assembly is further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a front view of a piston used in the first embodiment.

FIG. 3 is a vertical cross-sectional view of a piston used in the first embodiment.

FIG. 4 is an enlarged cross-sectional view of a main part when the differential device according to the first embodiment is differentially rotating at high speed.

FIG. 5 is an enlarged cross-sectional view of a main part when the differential gear of the first embodiment is differentially rotating at a low speed.

FIG. 6 is a performance diagram of the differential device according to the first embodiment.

FIG. 7 is a front view of a piston used in the second embodiment.

FIG. 8 is a sectional view of a conventional example.

FIG. 9 is a performance diagram of a conventional example.

[Explanation of symbols]

 1 Differential Device 3 Differential Case 23 Pinion Gear 25, 27 Output Side Gear 45 Differential Gear Mechanism 49 Multiple Disc Clutch (Friction Clutch) 53 Hydraulic Actuator (Actuator) 55 Gear Pump (Pump) 57 Piston 91 First Orifice 93 second orifice (other orifice) 95 coil spring (spring)

Claims (2)

[Claims] 1. A differential gear mechanism in which any one of three members of a differential case and a pair of side gears is rotationally driven by a driving force of an engine and outputs from the remaining two members of the three members via a pinion gear, A friction clutch that limits the differential of the differential gear mechanism, a pump that is driven by the differential rotation of the differential gear mechanism, and the friction clutch is pressed and engaged via a piston that receives the discharge pressure of the pump. Actuator and the first to let the working pressure of the actuator escape to the outside
And another orifice provided on the piston and closed by the friction clutch when the piston presses the friction clutch, and an actuator when the differential gear mechanism differentially rotates at a low speed and the discharge pressure of the pump is lower than a predetermined value. And a spring that pushes the piston back to the disengagement side of the friction clutch against the pressing force of the clutch. 2. The differential device according to claim 1, wherein the opening area of the other orifice is larger than the opening area of the first orifice.