JPH11351273A - Piston for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent clutch plates from being injured by a piston to smoothen the operation of the clutch by forming the annular contact part of a piston main body made of sheet metal so as to contact with the annular plate-like center of the clutch plates. SOLUTION: In a piston, a piston main body 1 made of sheet metal is integratedly provided with a rubber coating part 2 by heating deposition or the like. The piston main body 1 is provided with an inner circumferential wall part 6, a pressure chamber corresponding wall part 3, and an annular contact part 4 of U-section, and the diametral dimension D4 is set so that the annular contact part 4 is contacted with the center C1 of annular plate-like clutch plates 5,.... The outer circumferential end edge 8 of the annular contact part 4 is bent on the outer diameter side, an outer lip part 7 is integratedly provided along it, and constituted of a part of the rubber coating part 2 so as to slidably contact with the inner circumferential face 9a of a cylindrical space 9. Consequently, when the annular contact part 4 is pressed against the clutch plates 5, no partial load is applied thereto, and hence the clutch plates 5 can be smoothly moved in parallel without slanting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piston for an automatic transmission.

[0002]

2. Description of the Related Art Automatic transmissions used in automobiles and the like incorporate a hydraulically operated clutch device, in which an annular piston is disposed in a cylindrical space. Reciprocates with hydraulic pressure and springs.
That is, as shown in FIGS. 6 and 7, a conventional piston of this type is provided with an annular piston main body 31 manufactured by performing a cutting process on an aluminum die cast, and inner and outer peripheral sides of the piston main body 31. And a sealing material 32 (eg, rubber D-ring or O-ring), and a cylindrical space (drum housing).
Mounted in 34.

[0003] The piston body 31 has an annular plate-shaped wall 35 corresponding to a pressure chamber, an inner peripheral wall 36 protruding from the inner peripheral edge of the pressure chamber corresponding wall 35, and a protruding outer peripheral edge of the pressure chamber corresponding wall 35. And a seal member 32 is mounted on the outer peripheral wall 37, respectively.

A fluid supply passage 39 is connected to the pressure chamber 38, and fluid is supplied to the pressure chamber 38 through the passage 39 so that the piston 40 is pressed as shown in FIGS. As a result, the relatively thick outer peripheral wall 37 as the annular contact portion 41 is pressed against the annular clutch plates 42. That is, the clutch plates 42 are fastened and released by the reciprocating motion of the piston 40 in the axial direction, thereby changing the gear ratio of the automatic transmission. (Note that 43 is a spring for returning the piston 40.)

[0005] As is clear from FIGS. 6 and 7,
The annular contact portion 41 is made of the aluminum die-cast
Therefore, it is comparatively thick and is inside the clutch plate.
Heart C _lIs pressed. In other words, a relatively thick circle
The center line of the thickness of the annular contact part 41 is the center of the clutch plate.
C_lAlmost matches.

However, recently, the production cost has been reduced,
With the downsizing of the mounting space, a piston 40 made of a sheet metal press as shown in FIG. 8 has been studied. That is, as shown in FIG. 8, the piston 40 has a piston body 31 made of a sheet metal press, and a rubber coating portion 46 having lip portions 44 and 45 on the inner and outer peripheral sides of the piston body 31 and integrally baking and welding. , Is provided.

Since it is made of a sheet metal press, the outer peripheral wall 37 of the piston body 31 (the annular contact portion 41) is relatively thin, and the outer peripheral wall 37 has a cylindrical space (drum housing) 34. Is formed so as to approach the inner peripheral surface 34a.

[SUMMARY OF THE INVENTION Accordingly, in the conventional sealing-piece sheet metal piston 40 shown in FIG. 8, with respect to the center C _l of the clutch plate, presses the position quite eccentric, giving a biased load to the clutch plate 42 As a result, there is a fear that a defect such as damage may occur.

Namely, the annular abutment 41 hanging down close to the inner circumferential surface 34a of the drum housing 34, as shown in FIG. 8, the center C _l of the clutch plate, with considerable eccentricity epsilon, Since the clutch plate 42 is pressed against the outer diameter, the clutch plate 42 is in a posture of falling down, and is easily damaged.

Further, as described above, the piston body 31 made of a sheet metal press often reduces the thickness of the sheet metal to a necessary minimum in order to reduce the cost and make the piston compact, so that the contact area with the clutch plate 42 is reduced. As a result, there is a problem that the clutch plate 42 is further damaged.

An object of the present invention is to prevent the clutch plate 42 from being damaged when the seal-integrated sheet metal piston presses the clutch plates 42.
And to realize smooth operation of the clutch plates 42 for a long period of time.

[0011]

In order to achieve the above-mentioned object, a piston for an automatic transmission according to the present invention is provided with a sheet metal having an annular contact portion formed in a protruding shape so as to contact and press an annular clutch plate. In the piston for an automatic transmission provided with a piston body made of a piston, the diameter of the annular contact portion is set so that the annular contact portion comes into contact with the center of the annular plate-shaped clutch plate. .

Further, the cross-sectional shape of the annular contact portion is formed in a U-shape so as to protrude toward the clutch plate. Further, the outer peripheral edge of the pressure chamber-corresponding wall portion of the sheet metal piston body is bent in a U-shaped cross section to be continuous with the annular contact portion, and the annular contact portion has a single-piece outer peripheral wall. Consisting of parts.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 and 2 show a piston P for an automatic transmission according to the present invention, which is used as a hydraulically operated piston in an automatic transmission used in an automobile or the like. That is, a clutch device operated by hydraulic pressure is provided inside the automatic transmission, and is used as a clutch piston or a cancel piston.

As shown in FIG. 1, an annular piston body 1 made of sheet metal, which is viewed from a direction parallel to the axis A, and a rubber coating 2 provided integrally with the piston body by heat welding or the like. . The piston body 1 includes an inner peripheral wall portion 6, a pressure chamber corresponding wall portion 3 (in a direction orthogonal to the axis A), and a pressure chamber corresponding wall portion 3.
And an annular abutting portion 4 protruding from an outer peripheral edge of the outer ring. The cross-sectional shape of the annular contact portion 4 is U-shaped, and the bottom wall portion 4a is formed in a flat surface so as to directly contact and press the annular plate-like clutch plates 5. You.

In addition, the annular plate-like clutch plate 5.
The center C _l of annular abutment 4 (bottom wall 4a of) are in contact, setting the diameter D ₄ of the annular abutment 4. Incidentally, At a present invention, the clutch plate 5 ... center C _l of alternately a plurality of held on the outer diameter side and inner diameter side are arranged in layers clutch plates 5 ... of (pressure extrusion pressure state ) Is defined to indicate a radial position near the center in the width direction of the annular belt-shaped contact portions that come into contact with each other.

An annular contact portion 4 having a U-shaped cross section
The outer peripheral edge 8 is bent toward the outer diameter side, and the outer lip portion 7 is integrally provided. The outer lip 7 slidably contacts the inner peripheral surface 9 a of the cylindrical space (drum housing) 9, and the outer lip 7 has a part of the rubber coating 2. Note that the outer peripheral edge 8 does not have to be bent toward the outer diameter side (in some cases).

In FIG. 1, the rubber coating 2 is provided on the inner peripheral wall 6.
And a pressure chamber 11 of the wall section 3 corresponding to the pressure chamber.
The outer lip portion 7 is integrally formed with a flat coating film portion 12 covering the side, a groove filling portion 13 buried in a concave groove of the annular contact portion 4 having a U-shaped cross section, and the outer lip portion 7. ing. (Although not shown, the rubber coating 2 may not be integrally formed, but may have a structure in which the inner lip and the outer lip are separated from each other.)

In FIG. 1, the other configuration and operation are the same as those in FIG. 8 (or FIG. 6, FIG. 7), and the description is omitted. Next, FIG. 3 is different from FIG. 2 in that the thickness of the rubber coating film in the concave groove 14 (on the pressure chamber side) of the annular contact portion 4 having a U-shaped cross section is changed. This is substantially the same as the portion (particularly, the flat coating film portion 12). This figure 3
There is an advantage of weight reduction. When rubber is filled in the concave groove (on the pressure chamber side) of the annular contact portion 4 having a U-shaped cross section as shown in FIG. 2, there is an advantage that the volume of the pressure chamber is reduced and the operation response is improved.

FIG. 4 shows another embodiment, in which the concave groove 14 of the contact portion 4 having a U-shaped cross section in FIG. 3 is narrowed (reduced) or completely closed, and The width dimension W of the wall portion 4a is set to be smaller (than FIG. 3). At this time, a slightly large outer flange portion (flange portion) is formed on the outer peripheral edge 8 to which the outer lip portion 7 is attached.

FIG. 5 shows still another embodiment, in which the annular contact portion 4 is formed of a single hanging wall. That is, in the piston body 1 made of sheet metal press, the wall 3 corresponding to the pressure chamber is provided.
Is stretched as it is in the form of a flat plate or through a slight step 15 to the vicinity of the inner peripheral surface 9a of the drum housing 9, and the outer peripheral edge 3a is once bent 180 ° in a laterally inverted U-shape, and further 90 °.
The outer peripheral wall portion (of a single-sheet structure) is formed by bending downward by an angle of °, and the outer peripheral wall portion constitutes the contact portion 4.
The diameter D _4, the (indicated by two-dot chain line) clutch plates 5 ... diameter of the center C _l a, thereby substantially coincide.
(Thus, the outer peripheral edge 3a of the pressure chamber corresponding wall portion 3 is
It is bent in a letter shape and continues to the annular contact portion 4. )

As described above, the contact portion 4 composed of a single-piece outer peripheral wall portion comes into contact with the center _Cl of the clutch plates 5. An outer lip 7 is attached to the outer peripheral edge 3a, and an inner peripheral surface 9 of a cylindrical space (drum housing) 9 is provided.
a is slidably in close contact with a.

[0023]

According to the present invention, the following significant effects can be obtained by the above-described structure.

According to the first aspect, when the annular contact portion 4 presses the clutch plate 5, the clutch plate maintains a planar state perpendicular to the axis A (falls) without giving an eccentric load. Without translation). As a result, no unreasonable external force acts on the clutch plate 5 and damage or the like can be prevented, and a failure can be prevented.

According to the second aspect, (in addition to the effect of the first aspect), a sufficient contact area with the clutch plate 5 can be secured (even though it is made of sheet metal). Further, even if the sheet metal thickness is reduced to the minimum necessary, there is no reduction in the contact area, so that the degree of freedom in design increases. According to claim 3, (the above claim 1)
The overall structure can be simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing a pressure receiving (pressing) state of a piston for an automatic transmission according to the present invention.

FIG. 2 is a sectional view of a main part of a piston.

FIG. 3 is a sectional view of a main part according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part showing another embodiment.

FIG. 5 is a cross-sectional view of a main part showing still another embodiment.

FIG. 6 is a sectional view of a main part showing a conventional example.

FIG. 7 is a sectional view of a main part of a conventional example showing a pressure receiving (pressing) state.

FIG. 8 is a sectional view of a main part showing another conventional example.

[Explanation of symbols]

Reference Signs List 1 piston body 3 wall corresponding to pressure chamber 3a outer peripheral edge 4 annular contact part 5 clutch plate C ₁ center of clutch plate D ₄ diameter

Claims (3)

[Claims] 1. An automatic transmission piston comprising a sheet metal piston body having a protruding annular contact portion for contacting and pressing a toroidal clutch plate. A piston for an automatic transmission, wherein the diameter of the annular contact portion is set so that the annular contact portion comes into contact with the center of the plate. 2. A sectional shape of the annular contact portion is formed as a U-shape so as to protrude toward the clutch plate.
The piston for an automatic transmission according to the above. 3. An outer peripheral edge of a wall portion corresponding to a pressure chamber of a piston body made of a sheet metal is bent into a U-shaped cross section and is continuous with an annular contact portion, and the annular contact portion has a single structure. The piston for an automatic transmission according to claim 1, comprising an outer peripheral wall portion of the piston.