JP5316776B2 - Piston for automatic transmission - Google Patents

Description

  The present invention relates to a piston for an automatic transmission that is incorporated in an automatic transmission such as an AT or a CVT of a vehicle such as an automobile and used for switching a clutch by being displaced in the axial direction.

  Automatic transmissions such as ATs and CVTs in automobiles have recently tended to be multistage, and the FF system has space limitations in the axial direction, so the piston (BPS) has a larger diameter especially in large capacity ATs. There is a tendency. For this reason, if the piston is manufactured as it is, a great number of man-hours are inevitable, and in order to avoid this, the piston body and the seal ring are separately manufactured and fitted. The seal ring seals pressure (pressure oil) that operates the piston body.

  FIG. 5 shows a conventional example of this type of separate fitting type (also referred to as a separate fitting type) piston (see Patent Document 1), which is configured as follows. FIG. 5B is a partially enlarged view of FIG.

  That is, as shown in FIG. 5 (A), a ring is partially incorporated in the clutch housing 1 of the automatic transmission shown in the figure, and is displaced in the axial direction (left and right in the figure) by hydraulic pressure to switch the clutch (not shown). The piston 11 has an annular piston main body 21 and a seal ring 31 fitted to the piston main body 21.

  As shown in an enlarged view in FIG. 5B, the piston main body 21 has an annular shoulder step portion 22 having an axial end surface 23 and a cylindrical peripheral surface 24 continuous thereto, and the shoulder step portion 22. The seal ring 31 is fitted to the front.

  The seal ring 31 includes a press-molded metal ring 32 and a rubber-like elastic body 41 attached to the metal ring 32. The metal ring 32 is a ring-shaped portion 33 that is fitted to the cylindrical peripheral surface 24 of the shoulder step portion 22, and an annular shape that is integrally formed with one end of the tubular portion 33 and faces the axial end surface 23 of the shoulder step portion 22. The flat portion 34 is integrally formed. The rubber-like elastic body 41 attached to the metal ring 32 is provided with a seal lip 42 slidably in close contact with the peripheral surface of the housing 1, and the piston body to seal between the piston body 21 and the seal ring 31. A seal bead 43 that is in close contact with the axial end surface 23 of the shoulder step portion 22 is provided. The seal lip 42 and the seal bead 43 are integrally formed with each other, and a film portion 44 made of a rubber-like elastic body is attached to the outer end surface 34a of the flat portion 34 of the metal ring 32 so as to make the both 42 and 43 continuous. .

  However, in the above prior art, when the piston 11 is assembled, when the seal ring 31 is fitted to the piston main body 21, the rubber-like elastic body film portion 44 of the seal ring 31 is attached to the jig (see FIG. (Not shown). Accordingly, the rubber-like elastic body film portion 44 may be damaged such as tearing or peeling at the time of pressing, and the seal lip 42, which is a key element as a seal, may be damaged.

Japanese Patent No. 3869248

  In view of the above, the present invention is a piston of a type in which a piston body and a seal ring are separately manufactured and fitted, and when the piston is assembled, a rubber-like elastic body is fitted when the seal ring is fitted to the piston body. An object of the present invention is to provide a piston for an automatic transmission that is devised so as not to be damaged.

  In order to achieve the above object, a piston according to the present invention is an automatic transmission piston that is incorporated in an automatic transmission and that is displaced in the axial direction to switch a clutch, and has an axial end surface and a cylindrical peripheral surface continuous therewith. A seal ring that is fitted to a shoulder step of a piston main body, and the seal ring includes a press-molded metal ring and a rubber-like elastic body attached to the metal ring, The metal ring includes a cylindrical portion that is fitted to the cylindrical peripheral surface of the shoulder step portion, and an annular flat portion that is integrally formed with the cylindrical portion and faces the axial end surface of the shoulder step portion. In the piston having, an annular metal claw that is in close contact with the axial end surface of the shoulder step portion of the piston main body is integrally formed at the radial end portion of the planar portion of the metal ring, and a rubber-like shape is formed on the outer end surface of the planar portion. Pressed part when assembling a metal exposed surface that is not covered with an elastic body It is characterized in that provided Te.

  In the prior art of FIG. 5 above, when the piston 11 is assembled, when the seal ring 31 is fitted to the piston main body 21, the rubber-like elastic film portion 44 of the seal ring 31 is pressed with a jig. This is because the outer end surface 34a of the flat portion 34 of the metal ring 32 is entirely covered with the rubber-like elastic body 41 and there is no portion that directly presses the metal ring 32. The outer end surface 34a of the flat portion 34 of the metal ring 32 is rubber. The flat elastic body 41 is entirely covered with a seal lip 42 provided on the outer peripheral portion of the flat portion 34 and a seal bead 43 provided on the inner peripheral portion of the flat portion 34, so This is because it is integrally formed through the connector 44.

  On the other hand, in the piston of the present invention having the above-described configuration, an annular metal claw is integrally formed at the radial end portion of the flat portion of the metal ring, and this metal claw is the axial end surface of the shoulder step portion of the piston body. Since this metal claw seals between the piston body and the seal ring in place of the seal bead, it is possible to omit the seal bead and the coating part from the above prior art configuration. It is said that. Therefore, in the present invention, a metal exposed surface in which the outer end surface of the flat portion of the metal ring is not covered with a rubber-like elastic body is newly set as a pressed portion at the time of assembly, and this metal exposed surface is set during assembly fitting. Pressed.

  Therefore, according to the present invention, when the piston is assembled, when the seal ring is fitted to the piston body, the metal ring is pressed instead of the rubber-like elastic body. It is possible to prevent damage from occurring. Further, since the metal claw is in close contact with the piston body and performs a sealing action, the sealing fluid does not leak between the piston body and the seal ring.

Sectional drawing of the principal part of the piston for automatic transmission which concerns on the Example of this invention. (A) is an expanded sectional view of the metal claw in the piston, (B) and (C) are sectional views showing other examples of the metal claw, respectively. (A) is principal part sectional drawing of the piston for automatic transmission which concerns on the other Example of this invention, (B) is an expanded sectional view of the metal nail | claw in the piston. Sectional drawing of the principal part of the piston for automatic transmission which concerns on the other Example of this invention. (A) is a half sectional view showing an assembled state of a piston for an automatic transmission according to a conventional example, and (B) is an enlarged sectional view of a main part of the piston.

The present invention includes the following embodiments.
(1) A metal claw having a thin wall and spring characteristics is provided at a contact portion of the seal ring (seal ring) with the piston body.
(2) The metal claws that are elastically deformed as described in (1) above are provided with a bead portion of an elastic body to further improve the sealing performance.
(3) In the seal portion ring, a thin metal pawl having a spring characteristic is provided at a contact point with the piston main body, and the elastically deformed metal pawl seals oil from the gap with the piston main body.
(4) A metal ring exposed part is provided in the seal part ring to improve the assemblability when fitted to the piston body.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a cross section of a main part of a piston 11 for an automatic transmission according to an embodiment of the present invention. The piston 11 according to the embodiment is incorporated in an automatic transmission such as an AT or CVT of a vehicle such as an automobile, and is used for switching a clutch by axial displacement by hydraulic pressure, and has the following configuration. Has been. In FIG. 1, the vertical direction in the figure is the axial direction, the left direction is the outer peripheral direction, and the right direction is the inner peripheral direction.

  In other words, a part of the ring is incorporated in the clutch housing 1 of the automatic transmission shown in the figure, and is displaced in the axial direction by hydraulic pressure to switch a clutch (not shown, generally a multi-plate clutch is used). A piston (BPS) 11 is provided. The piston 11 has an annular piston main body 21 and a seal ring 31 which is a separate part fitted to the piston main body 21.

  The piston body 21 is formed of a press-molded metal ring, and has an annular shoulder step portion 22 having an axial end surface 23 and a cylindrical peripheral surface 24 continuous thereto, and is separately manufactured on the shoulder step portion 22. The seal ring 31 is fitted.

  The seal ring 31 includes a press-molded metal ring 32 and a rubber-like elastic body 41 attached to the metal ring 32. The metal ring 32 is formed integrally with one end of the cylindrical portion 33 that is fitted to the cylindrical peripheral surface 24 of the shoulder step portion 22, and faces the axial end surface 23 of the shoulder step portion 22. An annular flat surface portion 34 is integrally provided. As the rubber-like elastic body 41 attached to the metal ring 32, a seal lip 42 that is slidably in close contact with the peripheral surface of the housing 1 is provided, and the rubber-like elastic body 41 is formed on the cylindrical portion 33 of the metal ring 32. It is attached only to the peripheral surface (outer peripheral surface).

  An annular metal claw 36 that is in close contact with the axial end surface 23 of the shoulder step portion 22 of the piston main body 21 is integrally formed at the inner peripheral end portion of the flat portion 34 of the metal ring 32. The metal claw 36 is thinner than the flat portion 34 and is provided obliquely toward the axial end surface 23 of the shoulder step portion 22, and when the assembly is completed, the distal end portion 36 a is elastic to the axial end surface 23. Has close spring characteristics.

  On the outer peripheral side of the metal claw 36, an annular metal exposed surface 37 not covered with the rubber-like elastic body 41 is provided on the outer end surface 34 a of the flat portion 34 of the metal ring 32. Since the flat elastic member 41 is not attached to the inner end surface 34b of the flat surface portion 34, both the axial surfaces 34a and 34b are exposed metal surfaces.

  In the piston 11 having the above configuration, when the seal ring 31 is fitted to the piston main body 21 when the piston 11 is assembled, as shown by the arrow D, the outer end surface 34a of the flat portion 34 of the metal ring 32 in the seal ring 31 is provided. The provided metal exposed surface 37 is pressed with a jig (not shown), and there is no rubber-like elastic body that is compressively deformed in this fitting process. The fitting process is completed when the inner end surface 34b of the flat surface portion 34 of the metal ring 32 abuts against the axial end surface 23 of the shoulder step portion 22, so that the fitting depth is always kept constant. Therefore, it is possible to prevent inadequate fitting from occurring.

  Further, in the fitting process, since the jig does not press the rubber-like elastic body 41 attached to the peripheral surface of the cylindrical portion 33 of the metal ring 32 at all, the rubber-like elastic body 41 is damaged due to breakage or peeling. Can be prevented from occurring.

  Further, since the metal claw 36 is in close contact with the axial end surface 23 of the shoulder step portion 22 and performs a sealing action, it is possible to prevent the pressure oil, which is a sealing fluid, from leaking between the piston body 21 and the seal ring 31. You can also.

  It is conceivable that the piston 11 according to the above embodiment is added / changed as follows.

(1) In the above embodiment, the cross-sectional shape of the metal claw 36 is a straight shape with a constant width from the base end portion 36b to the tip end portion 36a as shown in an enlarged view in FIG. Instead of this, a tapered shape with a taper as shown in FIG. Alternatively, as shown in FIG. 2C, a tapered stepped shape is used. In the latter case, the stepped portion 36 c is provided on the lower surface side of the metal claw 36.

(2) In the above embodiment, when the piston 11 is assembled, when the seal ring 31 is fitted to the piston body 21, the inner end surface 34 b of the flat portion 34 of the metal ring 32 is formed on the axial end surface 23 of the shoulder step portion 22. The fitting process is supposed to be completed by abutting, but instead, the tip end portion 33a of the cylindrical portion 33 of the metal ring 32 abuts on the end surface portion 26 provided in the piston main body 21. The fitting process will be completed. That is, the positioning reference surface for fitting is set not at the inner end surface 34 b of the flat portion 34 of the metal ring 32 but at the tip end portion 33 a of the cylindrical portion 33 of the metal ring 32. In this case, the metal claw 36 is in close contact with the axial end surface 23 of the shoulder step portion 22 of the piston main body 21 as in the above embodiment, but the inner end surface 34b of the flat portion 34 of the metal ring 32 is not a positioning reference surface, so the shoulder. Without contacting the axial end surface 23 of the stepped portion 22, an axial gap is formed between the both 34 b and 23. The distal end portion 33a of the cylindrical portion 33 of the metal ring 32 is preferably bent outward (provided with an outward flange portion 38) so that the thickness surface thereof does not become a contact surface.

(3) In addition to the configuration of the above embodiment, as shown in FIG. 3A, a rubber-like elastic body 44 is attached to the metal claw 36, and this rubber-like elastic body 44 is attached to the end face in the axial direction of the shoulder step portion 22. By making it closely contact with 23, a sealing performance is improved. As shown in an enlarged view in FIG. 3B, the rubber-like elastic body 44 is attached so as to cover the entire metal claw 36, but is attached only to the contact portion with respect to the axial end face 23. There may be. Further, as shown in the figure, a sealing bead 45 may be provided on the rubber-like elastic body 44 to further improve the sealing performance. The rubber-like elastic body 44 is separate from the rubber-like elastic body 41 in the above embodiment.

(4) In the example of the above (3), the rubber-like elastic bodies 41 and 44 are separate from each other. However, as shown in FIG. In this case, in order to secure the metal exposed surface 37, a protruding metal exposed portion 39 is provided on the flat portion 34 of the metal ring 32. A plurality of protruding metal exposed portions 39 are provided at regular intervals on the circumference.

DESCRIPTION OF SYMBOLS 1 Housing 11 Piston 21 Piston main body 22 Shoulder step part 23 Axial end surface 24 Cylindrical peripheral surface 26 End surface part 31 Seal ring 32 Metal ring 33 Cylindrical part 33a, 36a Tip part 34 Planar part 34a Outer end face 34b Inner end face 36 Metal nail 36b Base end portion 36c Stepped portion 37 Metal exposed surface 38 Flange portion 39 Metal exposed portion 41, 44 Rubber elastic body 42 Seal lip 45 Seal bead

Claims (1)

A piston for an automatic transmission that is incorporated in an automatic transmission and switches a clutch by axial displacement and is fitted to a shoulder step portion of a piston body having an axial end surface and a cylindrical peripheral surface continuous thereto. The seal ring has a press-molded metal ring and a rubber-like elastic body attached to the metal ring, and the metal ring has a cylindrical periphery of the shoulder step portion. In a piston having a cylindrical part fitted to a surface, and an annular flat part integrally formed with the cylindrical part and facing an axial end surface of the shoulder step part,
An annular metal claw that is in close contact with the axial end surface of the shoulder step portion of the piston body is integrally formed at the radial end portion of the flat portion of the metal ring, and a rubber-like elastic body is coated on the outer end surface of the flat portion. A piston for an automatic transmission, wherein an exposed metal exposed surface is provided as a pressed portion during assembly.

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