JPH0226320A - Multiple disc clutch and multidisc type brake - Google Patents

Abstract

PURPOSE:To shorten a span of clamping time as well as to reduce a clamping shock by varying a sectional area of an oil passage, feeding a pressure chamber between a cylinder and a piston with oil pressure with the movement of the piston. CONSTITUTION:A cylinder side oil passage 32 is installed in an inner cylinder part 10b of a clutch drum 10. This cylinder side oil passage 32 is constituted of a ring groove 32a and a hole 32b, while a piston side oil passage 34 is installed in a piston 12, and this piston side oil passage 34 is composed of a casting hole 34a and a hole 34b. With this constitution, since a sectional area of the oil passage feeding a pressure chamber 30 between a cylinder 10 and the piston 12 with oil pressure is varied to some extent, this piston 12 is quickly moved immediately after movement of the piston 12, and this moving speed of the piston 12 is lowered at the final stage of clamping. Therefore clamping time is shortened, and a clamping shock is thus reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a multi-disc clutch and a multi-disc brake.

(B) Prior Art A conventional multi-disc clutch and multi-disc brake is disclosed in, for example, Japanese Patent Laid-Open No. 60-84428. The multi-disc clutch shown here includes a cylinder, a piston, and a friction plate. A pressure chamber is formed between the cylinder and the piston. When no hydraulic pressure is applied to the pressure chamber, no pressing force is applied to the friction plate.

When hydraulic pressure acts on the pressure chamber, the piston moves forward, and a pressing force acts on the friction plate, resulting in a fastened state.

(c) Problems to be solved by the invention However, the conventional multi-disc clutch as described above has
There is a problem in that a cushion mechanism is not provided to cushion the tightening shock.

That is, the hydraulic pressure supplied to the pressure chamber is supplied, for example, through a fixed orifice, and the hydraulic pressure supply speed at the start of engagement is the same as the hydraulic pressure supply speed at the end of engagement. For this reason, the fastening shock upon completion of fastening is large. Incidentally, if the cross-sectional area of the orifice in the middle of the oil passage is reduced, the fastening shock can be reduced, but in this case, a problem arises in that the fastening time becomes too long.

For example, Figure 4-21 on page 56 of "Hydraulic Textbook (Revised and Expanded Edition)" published by Nikkan Kogyo Shimbun on February 20, 1975 shows that the movement speed of the piston is reduced in the final movement stage. A mechanism for obtaining cushioning action is shown. That is, when the piston moves due to the action of the hydraulic pressure in the pressure chamber, the oil in the opposing chamber on the opposite side of the pressure chamber is discharged. When the piston moves to a predetermined position, the oil discharge passage in the opposing chamber is made smaller and the resistance to oil discharge is increased. This reduces the moving speed of the piston and provides a cushioning effect. However, such a mechanism
It cannot be applied to multi-disc clutches in automatic transmissions. This is because there is no opposing chamber in multi-disc clutches in automatic transmissions, and the piston moves forward only against the force of the return spring.

Note that, for example, as shown in Japanese Patent Application Laid-Open No. 62-62047, the clutch supply pressure is controlled by controlling the duty ratio of the solenoid valve, and the hydraulic pressure supply speed from the start of engagement to the completion of engagement is controlled. is also possible, but in this case a solenoid, computer, sensor, etc. would be required, which would significantly increase the price and also increase the size of the device.

The present invention aims to solve the above problems.

(d) Means for Solving the Problems The present invention solves the above problems by changing the cross-sectional area of the oil passage as the piston moves. That is,
The present invention comprises a rotatable cylinder (10), a piston (1
2), the cylinder has a return spring (14) and friction plates (16 and 18), and the cylinder has an inner cylindrical part (10
b) has an outer cylinder part (10a) and a side wall part (10c) connecting one end side of both cylinder parts, and the piston is fitted into an annular hole formed by the inner cylinder part and the outer cylinder part of the cylinder. The piston moves toward the friction plate against the force of the return spring by the hydraulic pressure acting on the pressure chamber (30) formed between the cylinder and the piston, so that the piston moves toward the friction plate. This target is a multi-disc clutch configured to apply a pressing force, and a cylinder-side oil passage (32) is provided in the inner cylindrical part of the cylinder to communicate the inside of the cylinder with the outside of the cylinder, and the piston A piston-side oil passage (34) that can connect the cylinder-side oil passage and the pressure chamber is provided on the inner circumferential part of , the piston is configured to be smaller when the piston moves toward the friction plate compression side than when the piston is pushed back to the stop position by the return spring. Note that the symbols in parentheses indicate corresponding members in the embodiments described later.

Note that the difference between a clutch and a brake is whether the cylinder rotates or is fixed, so the present invention can be similarly applied to the brake.

(E) When the working piston is pushed back to the stop position by the return spring, the connecting portions of the cylinder-side oil passage and the piston-side oil passage completely overlap each other and have a large cross-sectional area. When hydraulic pressure is supplied to the cylinder-side oil passage in this state, the oil pressure is relatively rapidly supplied to the pressure chamber through the piston-side oil passage. Therefore, the piston moves rapidly. When the piston moves toward the friction plate,
The cross-sectional area of the connection between the cylinder-side oil passage and the piston-side oil passage is reduced. Therefore, the hydraulic pressure supply speed decreases, and the piston movement speed also decreases accordingly. Therefore, the torque capacity of the friction plate increases gradually, and the fastening shock is alleviated.

(F) Example (First Example) A first example is shown in FIG. A piston 12, a return spring 14, a friction plate 16 (metallic clutch plate), a friction plate 18 (clutch plate with a facing), a retainer plate 20, and a snap ring 22 are contained in a clutch drum 10 rotatably supported by a fixed shaft 50. are arranged as shown. Note that the clutch drum 10 has an outer cylinder part 10a, an inner cylinder part 10b, and a side wall part 10c that connects one end side of both cylinder parts.

The splines on the outer diameter portion of the friction plate 16 are engaged with the splines on the outer cylindrical portion 10a of the clutch drum 10, and the friction plate 16 rotates together with the clutch drum 10. On the other hand, the splines on the inner diameter side of the friction plate 18 are engaged with the splines on the outer diameter side of the rotating member 24.
The friction plate 18 rotates together with the rotating member 24. The piston 12 is fitted into an annular hole formed by the outer cylindrical portion 10a and the inner cylindrical portion 10b of the clutch drum 10, with the inner and outer diameters thereof being sealed by seal members 26 and 28, respectively. As a result, the clutch drum 10
A pressure chamber 30 is formed between the piston 12 and the piston 12 .

A cylinder side oil passage 32 is provided in the inner cylindrical portion 10b of the clutch drum 10. The cylinder side oil passage 32 includes an annular groove 32a provided on the outer circumferential side of the inner cylindrical portion 10b over the entire circumference, and a hole 32b reaching the annular groove 32a from the inner periphery of the inner cylindrical portion 10b. Note that a plurality of holes 32b are provided. On the other hand, the piston 12 is provided with a piston-side oil passage 34. Piston side oil path 3
4 is a cast hole 34a extending in the axial direction and a piston 12.
A hole 3 extending radially from the inner peripheral side to the cast hole 34a.
4b. Note that a plurality of holes 34b are provided. The axial position of the six 34b is such that it coincides with the axial position of the annular groove 32a when the piston 12 is pushed back by the return spring 14 to the stop position (the position shown in FIG. 1). That is, in the state shown in FIG. 1, the entire cross section of the opening on the inner peripheral side of the hole 34b faces the annular groove 32a.

Next, the operation of this embodiment will be explained.

Since no oil pressure acts on the pressure chamber 30 when oil pressure is not supplied to the cylinder side oil passage 32, the piston 12 is pressed to the stop position by the return spring 14, and the friction plate 16 and the friction plate 18 are subjected to a pressing force. does not work. Therefore, the clutch is in a released state.

When oil pressure is supplied to the cylinder-side oil passage 32 from this state, it is supplied to the pressure chamber 30 through the piston-side oil passage 34. At this time, the oil flows into the pressure chamber 30 without receiving any resistance.
rapidly flowing into the interior. This is because the entire opening of the hole 34b faces the annular groove 32a, ensuring a sufficient flow path cross-sectional area. When hydraulic pressure acts on the pressure chamber 30, the piston 12 begins to stroke rightward in FIG. When the piston 12 strokes to the right in FIG. 1, the opening of the hole 34b is removed from the annular groove 32a,
A portion of the opening is now closed. The cross-sectional area of the opening of the hole 34b facing the groove 32a gradually becomes smaller as the piston 12 strokes. Therefore, an orifice effect occurs and the speed of oil flowing into the pressure chamber 30 decreases. As a result, the moving speed of the piston 12 decreases. As a result, the piston 12 moves forward gently when the friction plate 16 and the friction plate 18 are in the fastened state, so that the fastening shock is reduced. Piston 12 finally moves to the position shown in FIG. In this way, the piston 12 moves rapidly during the first stage of the idle stroke, and during the final stage of exerting a pressing force on the friction plates 16 and 18, the piston 12 moves slowly. Fastening shock can be reduced without extending the time.

(Second Embodiment) A second embodiment is shown in FIGS. 3 and 4. In this second embodiment, the cylinder-side oil passage 32 is a hole, and the piston-side oil passage 34 is an annular groove provided in the inner peripheral portion of the piston 12. As shown in FIG. 4, a throttle wall 35 is provided at a position in the circumferential direction of the annular groove 34 corresponding to the cylinder side oil passage 32. When the piston 12 moves in the direction of pressing the friction plates 16 and 18, the throttling wall 35 partially closes the opening of the cylinder side oil passage 32, producing a throttling effect. Thereby, the same functions and effects as in the first embodiment can be obtained. Note that the throttle wall 35 needs to be arranged at the same circumferential position as the cylinder side oil passage 32. For this purpose, the piston 12 is positioned in the circumferential direction by fitting a pin 40 fixed to the clutch drum 10 into a hole in the piston 12.

(g) As described in detail, according to the present invention, the cross-sectional area of the oil passage that supplies hydraulic pressure to the pressure chamber between the cylinder and the piston changes as the piston moves. Therefore, the piston can be moved relatively quickly immediately after the piston starts moving, and the moving speed of the piston can be reduced in the final stage of fastening. Furthermore, since the necessary structures for this purpose are grooves, holes, etc. provided in the piston and cylinder, the structure is extremely simple and can be realized at low cost.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the first embodiment of the present invention, Fig. 2 is a diagram showing the state in which the piston of the first embodiment has moved, and Fig. 3 is a diagram showing the state in which the piston of the first embodiment has moved.
FIG. 4, a diagram showing the embodiment, is a view taken along the line IV-IV in FIG. 3. . 10...Cylinder, 12...Piston, 16.18
...Friction plate, 30...Pressure chamber, 32...Cylinder side oil passage, 34...Piston side oil passage. Fig. Fig. Fig. ■” Fig.

Claims (1)

[Claims] 1. It has a rotatable cylinder, a piston, a return spring, and a friction plate, and the cylinder has an inner cylinder part, an outer cylinder part, and a side wall part connecting one end side of both cylinder parts. , the piston is fitted into an annular hole formed by the inner cylinder part and the outer cylinder part of the cylinder and is movable in the axial direction, and the piston is returned by the hydraulic pressure acting on the pressure chamber formed between the cylinder and the piston. In a multi-disc clutch configured to apply a pressing force to the friction plate by moving forward toward the friction plate against the force of a spring, the cylinder side communicates the inside of the cylinder with the outside of the cylinder through the inner cylindrical part of the cylinder. An oil passage is provided on the inner circumference of the piston, and the piston side oil passage is provided on the inner circumference of the piston to connect the cylinder side oil passage and the pressure chamber. The cross-sectional area of the overlapping portion is configured to be smaller when the piston moves toward the friction plate compression side than when the piston is pushed back to the stop position by the return spring. plate clutch. 2. The cylinder side passage is a groove provided in the circumferential direction in the inner cylindrical part of the cylinder, and the piston side passage is a hole that opens on the inner circumference of the piston, and when the piston is at the stop position, the above hole of the piston 2. The multi-function device according to claim 1, wherein the opening is aligned in the axial direction with the groove of the cylinder, and when the piston moves toward the compression side of the friction plate, the opening of the hole of the piston is partially out of alignment with the groove in the cylinder in the axial direction. plate clutch. 3. The cylinder side passage is a hole provided so as to open into the inner cylindrical part of the cylinder, and the piston side passage is a groove provided in the circumferential direction in the inner periphery of the piston, and on the piston side, the piston 2. A multi-disc clutch according to claim 1, further comprising a throttling wall which opens said bore in the cylinder when in the stop position and partially closes said bore in the cylinder when the piston moves toward the friction plate compression side. 4. It has a fixed cylinder, a piston, a return spring, and a friction plate, and the cylinder has an inner cylindrical part, an outer cylindrical part, and a side wall part that connects one end side of both cylindrical parts, and the piston is attached to the inside of the cylinder. It is fitted into an annular hole formed by the cylindrical part and the outer cylindrical part and is movable in the axial direction, and the piston resists the force of the return spring by the hydraulic pressure acting on the pressure chamber formed between the cylinder and the piston. In a multi-disc brake configured such that a pressing force is applied to the friction plate by moving forward toward the friction plate, a cylinder-side oil passage that communicates between the inside of the cylinder and the outside of the cylinder is provided in an inner cylindrical portion or an outer cylindrical portion of the cylinder. A piston-side oil passage is provided on the inner or outer periphery of the piston to connect the cylinder-side oil passage and the pressure chamber.
The cross-sectional area of the overlapping part of the cylinder-side oil passage and the piston-side oil passage is larger when the piston moves toward the friction plate compression side than when the piston is pushed back to the stop position by the return spring. A multi-disc brake characterized by being configured to be small.