JP2000320573A - Clutch piston for fluid-type transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To light a weight so as to ensure sufficient rigidity and durability by forming a cylindrical part guided on the annular inner wall surface of a clutch cylinder in large and small two steps, and integratedly and continuously disposing an annular plate part along a diameter direction on the axial end of the small diameter cylindrical part. SOLUTION: Seal lips 30, 31 are fitted to an inner cylindrical part 19 and an outer cylindrical part 20 of a clutch piston 11 to ensure oil pressure for operating the clutch piston 11. A fastening margin is controlled, so as to be brought in linear contact or brought in surface contact a tip end of the lip with an outer peripheral surface of an inner cylindrical part 9 of the clutch cylinder 3 and an inner circumferential surface of the outer cylindrical part 10. In the clutch piston 11, the outer cylindrical part 20 guided on an annular inner wall surface of the clutch cylinder 3 is formed into large and small shapes of two steps. Since a step difference size between a small diameter part 21 and a large diameter part 22 in the outer cylindrical part 20 is rationalized, weight can be lightened, using a thin wall plate material, so that rigidity and durability can be ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clutch piston for a hydraulic transmission mounted on, for example, an automobile.

[0002]

2. Description of the Related Art In a conventional hydraulic transmission, simply, when operating oil is supplied to a hydraulic chamber on one side of a clutch piston, the clutch piston is moved along a guide surface of the clutch cylinder. The drive plate on the drive shaft side and the driven plate on the driven shaft side are pressed against each other.

[0003] With respect to such a clutch piston,
It is necessary to secure sufficient rigidity so that the clutch piston does not bend when hydraulic pressure is applied. In order to secure this rigidity, the plate thickness of the clutch piston may be increased, but this is against the demand for weight reduction.

[0004]

On the other hand, the applicant of the present application has considered to increase the rigidity by bending the clutch piston stepwise. Specifically, in the clutch piston, the cylindrical portion guided by the annular inner wall surface of the clutch cylinder is formed in two stages, large and small, and the annular plate portion along the radial direction is integrally connected to the shaft end of the small-diameter cylindrical portion. I have. In addition, if the step is increased, the processing cost is increased, so that it cannot be increased.

In a clutch piston having such a shape,
Although the rigidity can be increased, it has been found that the durability is reduced unless the step size is properly managed. In other words, when a difference is generated between the stress acting on the connecting angle between the small-diameter tubular portion and the annular plate portion and the connecting angular portion between the large-diameter tubular portion and the annular step wall portion due to the application of the oil pressure, the stress is increased. The connection corners on the side where frustration is likely to be fatigued and damaged at an early stage.

In view of such circumstances, an object of the present invention is to provide a clutch piston of a fluid type transmission having a structure capable of securing sufficient rigidity and durability while reducing the weight.

[0007]

According to the first aspect of the present invention, a clutch piston of a hydraulic transmission is axially slidably accommodated in an annular space of a clutch cylinder and formed between the clutch piston and an inner wall surface of the clutch cylinder. A clutch piston of a hydraulic transmission that switches a multi-plate clutch between a power transmission state and a power transmission cutoff state by controlling the hydraulic pressure in a hydraulic chamber, and a tubular portion guided by an annular inner wall surface of the clutch cylinder is provided. Is formed in two stages, large and small, and has a shape in which an annular plate portion along the radial direction is integrally connected to the shaft end of the small-diameter cylindrical portion, and the radial position of the small-diameter cylindrical portion is set in accordance with hydraulic pressure application. It is specified at a position that satisfies the condition that each stress acting on the connecting corner between the small-diameter tubular portion and the annular plate portion and the connecting angular portion between the large-diameter tubular portion and the annular step wall portion is less than the allowable level.

According to a second aspect of the present invention, in the clutch for a hydraulic transmission according to the first aspect, the radial position of the small-diameter cylindrical portion is determined by the area of the annular plate portion and the area of the annular step wall portion. It is specified at a position where the ratio to the area is approximately 2: 1.

As described above, according to the present invention, in order to secure a sufficient rigidity after reducing the weight of the clutch piston by using a thin plate material, the cylindrical portion guided by the annular inner wall surface of the clutch cylinder has two stages, large and small. In order to ensure the durability of the stepped tubular portion, the step size between the small-diameter tubular portion and the large-diameter tubular portion of the tubular portion is optimized.

That is, by specifying the step size of the stepped cylindrical portion of the clutch piston as described above,
Since the respective stresses acting on the two connecting corners existing in the stepped cylindrical portion can be suppressed to below an allowable level, sufficient rigidity and durability can be ensured while using a thin plate material for weight reduction. become.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described with reference to embodiments shown in the drawings.

1 to 3 show an embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a main part of a hydraulic transmission,
FIG. 2 is a sectional view of the upper half of the clutch piston alone, and FIG.
3 is a graph showing a relationship between a radial dimension of a small-diameter cylindrical portion of a clutch piston and a stress acting on each connection corner.

In FIG. 1, reference numeral 1 denotes a driving shaft, and 2 denotes a driven shaft. A clutch cylinder 3 is connected to the drive shaft 1, a clutch hub 4 is connected to the driven shaft 2, and a plurality of driven plates 5 and one retainer plate 6 are provided on the inner peripheral surface of the clutch cylinder 3. A plurality of drive plates 7 are respectively attached to the outer peripheral surface of the hub 4. These plates 5 to 7 constitute a multi-plate clutch.

The clutch cylinder 3 has an inner cylindrical portion 9 and an outer cylindrical portion 10 which are concentric with the inner and outer circumferences of an annular plate portion 8 extending in the radial direction.
The clutch piston 11 is housed in an annular space formed between the inner cylindrical portion 9 and the outer cylindrical portion 10 so as to be slidable in the axial direction. A coil spring 14 is interposed in a compressed state between the clutch piston 11 and a spring receiving plate 13 retained by a snap ring 12 locked to the inner cylinder portion 9 of the clutch cylinder 3. The coil piston 14 elastically urges the clutch piston 11 toward the annular plate portion 8.

A hydraulic chamber 15 formed of an annular space is formed between one side surface of the clutch piston 11 and the inner surface of the clutch cylinder 3. Through hole 16 provided in
Is connected to an oil supply passage 17 provided in the drive shaft 1 through the shaft. That is, by controlling the supply or recovery of the operating oil to the hydraulic chamber 15, the clutch piston 11 is slid to the right or left in FIG. 1 to bring the driven plate 5 and the drive plate 7 into a pressed state or a separated state, and Power is transmitted from the shaft 1 to the driven shaft 2 or power is cut off.

Next, the clutch piston 11 will be described in detail. The clutch piston 11 has a shape in which an inner cylindrical portion 19 and an outer cylindrical portion 20 are provided concentrically on the inner and outer circumferences of an annular plate portion 18 extending in the radial direction.

The outer cylindrical portion 20 is formed in two steps, a large diameter portion 21 and a small diameter portion 22, and the small diameter portion 21 is located on the annular plate portion 18 side. The reason why the outer cylindrical portion 20 is formed in two stages, large and small, is to increase rigidity without increasing the plate thickness.
The radial position of the connecting portion A between the small-diameter cylindrical portion 21 and the annular plate portion 18 and the large-diameter cylindrical portion 22
It is preferable to specify a position that satisfies the condition for making the stresses concentrated on the connection corner B between the and the annular step wall 23 substantially the same. This is because, depending on the position of the small-diameter cylindrical portion 21 in the radial direction, the stress concentrated on one of the two connecting corners A and B becomes excessively large, so that the portion is easily damaged by fatigue. Therefore, the stress acting on the two connecting corners A and B was examined by variously changing the radial position of the small-diameter cylindrical portion 21, and the stress is described with reference to the graph of FIG.

That is, the position of the small-diameter cylindrical portion 21 in the radial direction,
That is, as the radius r3 of the small-diameter cylindrical portion 21 is increased, the stress acting on the connecting corner portion A gradually increases, while the stress acting on the connecting corner portion B gradually decreases.

As can be seen from the graph of FIG. 3, if the stress acting on both connecting corners A and B is substantially the same as a guide, the optimum position of the small-diameter cylindrical portion 21 in the radial direction is determined. Can be specified.

The optimum position of the small-diameter cylindrical portion 21 in the radial direction is determined by the donut-shaped front projection area of the annular plate portion having the radial width H1 from the inner cylindrical portion 19 to the small-diameter cylindrical portion 21 and the small-diameter cylindrical portion 21. It can be said that this is a position where the ratio of the annular step wall portion having the radial width H2 (step size) from the to the large-diameter cylindrical portion 22 to the donut-shaped front projected area is approximately 2: 1.

Incidentally, the radius r3 of the small-diameter cylindrical portion 21 for satisfying the condition that the stresses acting on the two connecting corner portions A and B are the same can be obtained by the following formula.

R3 = {(r1 ² + 2r2 ² ) / 3} In the above formula, r1 is the radius of the inner cylinder 19, r
Reference numeral 2 denotes a radius of the large-diameter cylindrical portion 22.

FIG. 3 shows that r1 = 20 mm and r2 = 35 mm
The results obtained by measuring the stress acting on the connection corners A and B when r3 is variously changed in the sample No. 3 are shown. In this case, the stress values acting on both connecting corners A and B are the same when r3 = 26 mm, which is almost the same as the result of the above formula. At this time, the stress applied to both connecting corners A and B is about 500 MPa.

However, it is most preferable that the respective stresses acting on the two connecting corners A and B are controlled to be the same. If the allowable level is defined in relation to the above, it can be said that there is no problem even if the stress acting on the two connecting corners A and B has a slight deviation. Assuming that the allowable level of each stress is defined by a dashed line in the graph of FIG. 3, the position of the small-diameter cylindrical portion 21 in the radial direction, that is, the radial dimension r3 is within the range of x1 (24 mm) to x2 (27 mm). And the degree of freedom in design can be increased.

By the way, seal lips 30 and 31 are respectively attached to the inner cylindrical portion 19 and the outer cylindrical portion 20 of the clutch piston 11, so that a hydraulic pressure for operating the clutch piston 11 is ensured. ing.

The seal lips 30 and 31 are respectively
The interference is controlled so that the tip of the lip makes line contact with or close to line contact with the outer peripheral surface of the inner cylinder portion 9 and the inner peripheral surface of the outer cylinder portion 10 of the clutch cylinder 3.

As described above, the clutch piston 1
Regarding 1, the outer cylindrical portion 20 guided by the annular inner wall surface of the clutch cylinder 3 has a large and small stepped shape, and the step size between the small-diameter cylindrical portion 21 and the large-diameter cylindrical portion 22 in the outer cylindrical portion 20 is appropriately adjusted. Therefore, it is possible to secure sufficient rigidity and durability after reducing the weight by using a thin plate material.

[0028]

According to the first and second aspects of the present invention, it is possible to secure sufficient rigidity and durability while reducing the weight of the clutch piston by using a thin plate material.
Therefore, since the bending of the clutch piston during the operation of the clutch of the fluid type transmission can be prevented, the operation of the clutch piston can be stabilized, and the life can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a hydraulic transmission according to an embodiment of the present invention.

FIG. 2 is a sectional view of the upper half of the clutch piston of FIG. 1;

FIG. 3 is a graph showing a relationship between a radial dimension of a small-diameter cylindrical portion of a clutch piston and a stress acting on each connecting corner portion.

[Explanation of symbols]

 Reference Signs List 3 clutch cylinder 4 clutch hub 5 driven plate 7 drive plate 8 annular plate portion of clutch cylinder 9 inner cylinder portion of clutch cylinder 10 outer cylinder portion of clutch cylinder 11 clutch piston 15 hydraulic chamber 18 annular plate portion of clutch piston 20 clutch piston Outer cylinder part 21 Small diameter cylinder part of outer cylinder part 22 Large diameter cylinder part of outer cylinder part 23 Annular stepped wall part

Claims (2)

[Claims] 1. A power transmission state and a power transmission cutoff of a multi-plate clutch by controlling a hydraulic pressure of a hydraulic chamber formed in an annular space of a clutch cylinder so as to be slidable in an axial direction and formed between the clutch cylinder and an inner wall surface thereof. A clutch piston of a hydraulic transmission that is operated to switch between a state and a state, wherein a cylindrical portion guided by an annular inner wall surface of the clutch cylinder is formed in two stages, large and small, and extends radially along a shaft end of the small-diameter cylindrical portion. The annular plate portion is integrally connected, and the radial position of the small-diameter tube portion is changed by the application of oil pressure to the connection angle portion between the small-diameter tube portion and the annular plate portion and the large-diameter tube portion and the annular step. A clutch piston for a hydraulic transmission, which is specified at a position that satisfies a condition that makes each stress acting on a joint angle portion with a wall surface portion less than an allowable level. 2. A clutch piston for a hydraulic transmission according to claim 1, wherein a ratio of an area of said annular plate portion to an area of said annular stepped wall portion is approximately 2 in a radial direction of said small-diameter cylindrical portion. A clutch piston for a hydraulic transmission, wherein the clutch piston is specified in a position to be paired.