JPH0756329B2 - Differential limiting device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a limited slip differential, and in particular, a plurality of friction plates are brought into contact with each other by an external operation to generate a frictional force, and the frictional force is utilized. And a device for limiting the differential.

(Prior Art) A first friction plate that engages one side gear with a differential generated by the action of a plurality of pinions and a pair of side gears respectively arranged in a differential case (hereinafter referred to as a case), a case or a case. As a device for limiting the frictional force based on the contact with the second friction plate engaged with the other side gear, a hydraulically actuated first piston is movably arranged on a differential carrier (hereinafter referred to as carrier), There is a case in which a second piston is movably arranged in a case, the second piston is engaged with a friction plate, and a thrust bearing is interposed between the two pistons (Japanese Patent Laid-Open No. 61-82048, actual opening). Sho 61-73430
Issue). In this limited slip differential device, the torque to be applied to the friction plate is determined by the magnitude of the hydraulic pressure applied to the first piston.

(Problems to be solved by the invention) Incidentally, the specifications of the friction plate are, for example, 70 kg at maximum with respect to the maximum torque determined by the tire diameter and the tire ground contact load.
Designed to add a hydraulic pressure of / cm ² . When trying to obtain a small torque such as when controlling the number of revolutions using this differential limiting device, a minute hydraulic pressure is naturally required, but the distance from the maximum hydraulic pressure to the minute hydraulic pressure is too large. ,
It is difficult to smoothly adjust the pressure of the pressure source.

An object of the present invention is to provide a differential limiting device capable of transmitting large torque and transmitting small torque without depending on pressure adjustment of a pressure source.

(Means for Solving the Problems) The present invention relates to a case and a first friction plate that engages one side gear with a differential generated by the action of a plurality of pinions and a pair of side gears respectively arranged in the case. Or a device for limiting by a frictional force based on contact with a second friction plate engaged with the other side gear, which is a piston chamber connected to an external pressure source and a hole opened in the axial direction from the piston chamber. And a liquid chamber connected to an external pressure source, the carrier having a pressure receiving area smaller than the pressure receiving area of the piston chamber, the carrier disposed surrounding the case, and the piston chamber of the carrier in the axial direction. A first piston movably disposed in the liquid chamber, the auxiliary piston being formed longer than the stroke of the piston and movably inserted in the liquid chamber in the axial direction. A first piston having an integral part, which is non-rotatable by the auxiliary piston part, a directional control valve which is switched to supply a pressure liquid from a pressure source to the piston chamber or the liquid chamber, the first piston A second piston rotatably arranged with the friction plate or the second friction plate and movable along the rotation axis of the case, and arranged between the first piston and the second piston. Including thrust bearings.

(Operation and effect) When the pressurized liquid is introduced into the piston chamber of the carrier from the outside, the first piston moves, and the second piston moves in accordance with this movement, so that the first friction plate and the second friction plate are separated. Apply pressing force. This limits the differential between the side gear and the case. When the supply of pressurized liquid to the piston chamber is stopped,
The first friction plate and the second friction plate can rotate relative to each other, and a differential operation is performed.

When the directional control valve is switched to introduce the pressurized liquid into the liquid chamber of the carrier, a small force is applied to the auxiliary piston portion of the first piston, and a small torque acts on the friction plate.

Since the carrier is provided with a piston chamber and a liquid chamber with a small pressure receiving area, a large torque and a small torque can be obtained only by switching the supply of the pressurized liquid by the directional control valve, and therefore pressure adjustment for that is not required. It is possible to eliminate the need for a highly accurate pressure control valve over a wide pressure range.

By absorbing the machining tolerance of the carrier and the machining tolerance of the first and second friction plates, the second piston, etc. by forming the piston chamber to a length that is larger than the first piston stroke. The adjustment shim, which is usually required when a large number of parts are stacked, can be omitted.

Since the piston slides in the piston chamber, its rigidity can be sufficiently increased.

Since the piston chamber connected to the external pressure source is provided in the carrier which is fixedly arranged, the seal for the rotating portion is not necessary.

Since the first piston integrally has the auxiliary piston, the number of parts does not increase. In addition, when the piston rotates relative to the carrier, wear of the sealing material disposed between the two poses a problem, but according to the present invention, the first piston is not rotatable by the auxiliary piston. Therefore, the above problem does not occur.

(Embodiment) The differential limiting device 10 applies to one side gear 16 a differential generated by the action of a plurality of pinions 14 and a pair of side gears 16 (each shown in the figure) arranged in the case 12. A plurality of first friction plates 18 that engage with each other, and a case
12 or the other side gear (case 1 in the illustrated embodiment
2) is limited by the frictional force based on the contact with the plurality of second friction plates 20 engaged with the first carrier 22.
And a second carrier 24, a first piston 26, a second piston 28, and a thrust bearing.
Including 30 and.

As is known per se, the differential device 32 includes the case 12, a plurality of pinions 14 arranged in the case 12, and a pair of side gears 26 arranged in the case 12 and meshing with the pinion 14. The case 12 is housed in the first carrier 22 and rotatably supported by the rolling bearing 34.

The shaft 36 is supported by the case 12 and the bearing 38. In the illustrated embodiment, the shaft is spline 37
The side gear 16 is fitted to the spline 37a. As a result, the shaft 36 can rotate around the axis of the case 12 together with the side gear 16. The shaft 36 extends from the first carrier 22 to the outside through a transmission member described later.

The shaft 36 has a spline 37b in its middle portion.
The ring 40 is fitted to the spline 37b, and is held by the retaining ring 42 and the race of the bearing 38. ring
40 has a spline 41, and a plurality of disc-shaped first friction plates
18 is fitted to the spline 41 and is supported so as to be movable in the axial direction and non-rotatable relative to the ring 40. ring
40 functions as a spacer, and absorbs a difference in the radial direction between the shaft 36 and a transmission member described later.

The transmission member 44 includes a hollow first transmission portion 45a and an enlarged second transmission portion 45b. First transmission portion 45a
Has a spline 45c, and this spline 45c has a case 12
Are fitted together, and the clamp ring 46 is arranged between them. As a result, the first transmission portion 45a is
Relative rotation is impossible and movement in the axial direction is impossible. The shaft 36 is arranged inside the first transmission portion 45a.

The second transmission portion 45b includes a disc-shaped holding portion 48 and a cylindrical support portion 49 that is press-fitted or welded to the holding portion 48 and extends in the axial direction of the shaft 36. A thrust washer 50 is arranged on the carrier 22 side of the holding section 48. Spline on support 49
49a is provided, a plurality of disc-shaped second friction plates 20 are fitted to the splines 49a, and the second friction plates 20 are supported by the support portion 49 so that they cannot rotate relative to each other and are movable in the axial direction. It

The first carrier 22 has a flange 54 attached by bolts 52. Thrust washers 56 on this flange 54
And a thrust bearing 58 is located between the thrust washers 50, 56.

The second carrier 24 has a hollow hole 25a and a flange 25b each having a size that surrounds the second transmission portion 45b of the transmission member 44. A bolt 60 is screwed into the flange 25b of the second carrier 24 and the flange 54 of the first carrier 22, and the second carrier 24 is attached to the first carrier 22. As a result, the transmission member
The second transmission portion 45b of 44 is surrounded by the second carrier 24, and the shaft 36 projects outward from the second carrier 24.

The second carrier 24 has a piston chamber 62 formed in an annular shape,
The liquid chamber 64 has a pressure receiving area smaller than the pressure receiving area of the piston chamber 62. Piston chamber 62 has passage 66 and passage
An external pressure source (secondary via a tube 68 connected to 66)
Communication). In the illustrated embodiment, the liquid chamber 64 comprises a plurality of holes opened in the axial direction from the piston chamber 62 at equal intervals in the circumferential direction of the piston chamber 62, and a passage 70 is formed in each hole.
Communicate with each other. A tube 72 is connected to the passage 70, and the liquid chamber 64 communicates with an external pressure source.

The first piston 26 is formed in an annular shape and is movably arranged in the piston chamber 62. The piston 26 is held liquid-tight by a seal ring 74 mounted in the piston chamber 62 and a seal ring 76 mounted on the outer peripheral surface. The first piston 26 has the same number of auxiliary piston portions 27 as the holes that form the liquid chamber 64 and project in the axial direction at equal intervals in the circumferential direction, and these auxiliary piston portions 27 are provided in the second carrier 24. It is inserted into the liquid chamber 64 of. The auxiliary piston portion 27 is held in a liquid-tight manner by a seal ring 78 mounted on its outer peripheral surface. The length of the auxiliary piston portion 27 that engages with the liquid chamber 64 is formed longer than the stroke of the piston 26, so that the piston 26 is supported so as not to rotate relative to the second carrier 24. That is, the auxiliary piston portion 27 is
It has a function of receiving pressure from and a function of stopping rotation of the piston 26.

Multiple coil springs 80 (one shown in the figure)
62 are arranged at equal intervals in the circumferential direction. The coil spring 80 is a compression spring and provides the minimum preload required to prevent the friction plates 18, 20 and the second piston 28 from axial rattling or tilting with respect to the axis. As a result, uneven wear and abnormal noise due to partial contact of the friction plates 18, 20 and the second piston 28 are prevented.

The second piston 28 is formed in an annular shape and is fitted in a spline 41 provided on the ring 40. As a result, the second piston 28 is supported so as not to rotate relative to the ring 40, and thus to the shaft 36, but movable in the axial direction thereof, and rotates together with the first friction plate 18. The second piston 28 may be supported by the second transmission portion 45b of the transmission member 44 such that it cannot rotate relative to the second transmission portion 45b but is movable in the axial direction.

A thrust bearing 30 is arranged between the first piston 26 and the second piston 28.

The supply of the pressure fluid from the external pressure source is automatically performed by a CPU or a computer as shown in FIG. In the embodiment shown in FIG. 2, tube 68 and tube 72 are connected to a directional control valve 82,
The directional control valve 82 is connected to a pump 86 via a constant pressure generation source 84. The constant pressure generation source 84 includes an unload relief valve 88, an accumulator 90, and a pressure reducing valve 92, and the pressure generated by the pump 86 is held in the accumulator 90 at a constant pressure.

When the directional control valve 82 is located in the neutral position in the drawing, the piston chamber 62 and the liquid chamber 64 are both opened to the reservoir tank 94, and when the first envelope 83a faces each tube, the piston chamber 62 is a constant pressure generation source 84. Fluid chamber 64 opens to reservoir tank 94 and second envelope 83b faces each tube, fluid chamber 64 communicates with constant pressure source 84 while piston chamber 62 opens to reservoir tank 94. Is formed so that Switching of direction control valve 82 and pressure reducing valve
The pressure setting of 92 is controlled by the CPU or computer 96.

In the illustrated embodiment, a first friction plate having a differential limiting action is provided.
18, the second friction plate 20 and the second piston 28 are arranged in the second carrier 24, and their shapes can be arbitrarily selected regardless of the size of the case 12, and the second piston 28 penetrates the case 12. Therefore, the contact area between the second piston 28 and the first friction plate 18 or the second friction plate 20 can be made sufficiently large due to the fact that it is not necessary to extend. This allows
A sufficient contact surface pressure can be secured and the device can be downsized.

(Operation of Embodiment) The ring gear 98 is attached to the case 12 of the differential gear 32,
A drive gear (not shown) meshes with the ring gear 98. When the propeller shaft (not shown) rotates, the case 12 of the differential device 32 rotates via the drive gear and the ring gear 98, and the rotation is extracted to the shaft 36 and another shaft (not shown).

When the CPU 96 determines that the differential should be limited with a large torque, the directional control valve 82 is switched to the first envelope 83a.
Faces tubes 68, 72. Then, the pressure liquid is supplied to the piston chamber 62 through the tube 68, and the first piston
26 is moved and the second piston 28 is moved. The movement of the second piston 28 causes the first friction plate 18 and the second friction plate 20 to move to the second piston 28 and the second transmission portion 45 of the transmission member 44.
It is clamped by b and a differential limiting torque is generated between the shaft 36 and another shaft (not shown). The pressing force at this time is transmitted from the thrust washer 50 to the thrust washer 56 via the thrust bearing 58, and is received by the first carrier 22.

When the CPU 96 determines that the differential should be limited with a small torque, the directional control valve 82 is switched to the second envelope 83b.
Faces tubes 68, 72. Then, the pressurized liquid is supplied to the liquid chamber 64 via the tube 72, and the first friction plate 18 and the second friction plate 20 are held with a small force.

When the supply of the pressure fluid from the pressure source is stopped, the pressing action of the second piston 26 disappears and the differential limiting torque disappears. This allows the differential device 32 to perform normal differential.

[Brief description of drawings]

FIG. 1 is a sectional view of a differential limiting device, the differential device shows the left half, and FIG. 2 is a circuit diagram of a hydraulic pressure source. 10: Differential limiting device, 12: Case, 14: Pinion, 16: Side gear, 18: First friction plate, 20: Second friction plate, 22: First carrier, 24: Second carrier, 26: Second 1 piston, 27: auxiliary piston part, 28: second piston, 30: thrust bearing, 30: thrust bearing, 36: shaft, 44: transmission member, 62: piston chamber, 64: liquid chamber, 82: direction control valve.

Claims (1)

[Claims] 1. A first friction plate engaged with one side gear and a differential case or the other side gear, and a differential generated by the action of a plurality of pinions and a pair of side gears respectively arranged in the differential case. And a piston chamber connected to an external pressure source, and a hole opened in the axial direction from the piston chamber, the piston chamber being limited by a frictional force based on contact with the second friction plate. A differential carrier having a pressure receiving area smaller than the pressure receiving area connected to an external pressure source, the differential carrier being arranged to surround the differential case, and movable in the axial direction into the piston chamber of the differential carrier. The first piston arranged in the A first piston that is integrally formed with the liquid chamber and is inserted into the liquid chamber so as to be movable in the axial direction, and is not rotatable by the auxiliary piston portion; and a pressure liquid from the pressure source. A directional control valve switched to supply to the piston chamber or the liquid chamber, and rotatable with the first friction plate or the second friction plate,
And a differential limit including a second piston movably arranged along the rotation axis of the differential case and a thrust bearing arranged between the first piston and the second piston. apparatus.