JP3893575B2 - Hydraulic servo device for automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly carry out a position determination of a piston and realize a change to a piston having a different outer-diameter. SOLUTION: In a hydraulic servo device of an automatic transmission which is provided with a piston 6 slidably provided in a cylinder chamber 15 and having a piston shaft 5; a first hydraulic chamber 17 provided at one end side of the piston 6 and moving the piston 6 toward a direction of releasing a band brake 4 by supplying an oil pressure; a second hydraulic chamber 18 moving the piston 6 toward a direction of connecting the band brake 4 by supplying the oil pressure; a piston retainer 8 disposed opposed to the piston 6 and sealing the second hydraulic chamber 18; and a snap ring 10 disposed between the piston 6 and the piston retainer 8 and carrying out a position determination of the piston 6, an annular member 12 is provided between the snap ring 10 and the piston 6.

Description

[0001]
[Industrial application fields]
The present invention relates to a hydraulic servo device for an automatic transmission.
[0002]
[Prior art and problems]
2. Description of the Related Art Conventionally, a hydraulic servo device for an automatic transmission has a structure as shown in FIG. 2, and a band brake 4 is provided on the outer periphery of the clutch drum. The band brake 4 is engaged and released from the clutch drum. The hydraulic servo device to be performed includes a piston 6 having a piston shaft 5, a first hydraulic chamber 17 that is formed on one end side of the piston 6 and moves the piston 6 in the release direction of the band brake 4 by being supplied with hydraulic pressure. A piston that is formed on the other end side of the piston 6 and is provided with a second hydraulic chamber 18 that moves the piston 6 in the fastening direction of the band brake 4 by supplying hydraulic pressure, and seals the second hydraulic chamber 18. A retainer 8 is configured so as to be opposed to the piston 6.
[0003]
In the hydraulic servo apparatus having such a conventional structure, the piston 6 needs to be changed to one having a different outer diameter in order to obtain a predetermined operating force according to the displacement of the engine. Since the structure is locked, there is a problem that positioning by the snap ring 10 becomes difficult if the outer diameter of the piston 6 is changed to a small one corresponding to a small displacement engine. Therefore, it is conceivable to reduce the inner diameter of the snap ring 10 and to increase the length in the radial direction with which the piston 6 abuts, so that it can be used for various pistons 6. However, such a snap ring 10 is difficult to mount, When a force is applied to the inner diameter side, a new problem arises that it tends to come off from the ring groove.
[0004]
[Means for Solving the Problems]
The present invention has been devised in view of the above-mentioned conventional problems, and does not provide a hydraulic servo device for an automatic transmission that can position the piston well even when the piston is changed to one having a different diameter. An object of the present invention is to provide a hydraulic servo apparatus for an automatic transmission that engages and releases a band brake provided on an outer periphery of a clutch drum of an automatic transmission with respect to the clutch drum, and a cylinder provided on a case member. And a piston having a piston shaft and slidably provided in the cylinder chamber, and provided at one end of the piston, and is supplied with hydraulic pressure to move the piston in a band brake releasing direction. Provided in the hydraulic chamber and the other end of the piston, the hydraulic pressure is supplied to move the piston in the band brake fastening direction. A second hydraulic chamber for being disposed opposite to said piston, automatic said piston retainer to seal the second hydraulic chamber, fitted to the case member, and a snap ring for positioning of said piston In the hydraulic servo apparatus of the transmission, a retainer having one end axially locked to the inner wall of the case member and having an inner diameter corresponding to the outermost diameter of the piston, and an inner diameter that is smaller than the inner diameter of the retainer An annular member that locks the other end of the retainer in the axial direction and that is locked in the axial direction by the snap ring and that is in contact with the piston at a smaller diameter than the inner diameter of the retainer; It is to provide.
[0005]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is an enlarged sectional configuration diagram of a hydraulic servo device of an automatic transmission for operating a band brake. A band brake 4 is provided on the outer periphery of the direct clutch drum 3, and the direct clutch drum 3 of the band brake 4 is provided. The hydraulic servo device 16 that engages and releases the piston 6 includes a piston 6 slidably movable in a cylinder chamber 15 formed in the case member 11 of the automatic transmission, and a screw 6a formed on the inner periphery of the piston 6. A nut 7 is screwed onto the piston shaft 5 screwed to the piston shaft 5 so that the projecting dimension of the piston shaft 5 can be adjusted by the nut 7. One end of the piston 6 is supplied with hydraulic pressure. Thus, a first hydraulic chamber 17 for moving the piston 6 in the release direction of the band brake 4 is formed, and a return spring is formed in the first hydraulic chamber 17. 14 is provided, always piston 6 is urged to the illustrated left direction by the return spring 14, the piston shaft 5 is maintained in a state of being separated from the band brake 4. On the other hand, a second hydraulic chamber 18 for moving the piston 6 in the fastening direction of the band brake 4 by supplying hydraulic pressure is formed on the other end side of the piston 6, and a piston retainer for sealing the second hydraulic chamber 18. 8 is arranged to face the piston 6.
[0006]
The piston retainer 8 is positioned and fixed to a case member 11 via a snap ring 9, and the piston 6 has an annular member 12 interposed inside a snap ring 10 fixed to the case member 11. Thus, the annular member 12 is positioned by contacting the outer peripheral end surface of the piston 6. Further, a retainer 13 is interposed in sliding contact with the outer periphery of the piston 6 on the side surface of the annular member 12, and a plurality of types of retainers 13 are set according to the engine displacement. Can be made common. The annular member 12 is composed of one type having a predetermined inner diameter and thickness regardless of the engine displacement.
[0007]
For example, when the piston 6 is changed to one having a short outer diameter, if only the snap ring 10 is used, the outer periphery of the piston 6 is not brought into contact with the snap ring 10 and positioning of the piston 6 is difficult. However, since the annular member 12 is interposed in this example, the piston 6 can be positioned by reliably contacting the annular member 12 even when the outer diameter of the piston 6 is short, The piston can be changed to one having a different outer diameter.
The projecting dimension of the piston shaft 5 is adjusted after the retainer 13, the piston 6, the annular member 12, and the snap ring 10 are assembled.
[0008]
【The invention's effect】
The present invention is a hydraulic servo device for an automatic transmission for fastening and releasing a band brake provided on an outer periphery of a clutch drum of an automatic transmission with respect to the clutch drum, and a cylinder chamber provided in a case member; A piston slidably provided in the cylinder chamber and having a piston shaft; a first hydraulic chamber provided on one end side of the piston for moving the piston in a release direction of the band brake by being supplied with hydraulic pressure; A second hydraulic chamber that is provided on the other end side of the piston and is moved in the band brake fastening direction when hydraulic pressure is supplied; and is disposed opposite the piston, and the second hydraulic chamber is a piston retainer for sealing fitted on the case member, oil of an automatic transmission and a snap ring for positioning of said piston In servo device, the locked to one axial end to the inner wall of the case member, wherein a retainer which is an inner diameter corresponding to the outermost diameter of the piston, the diameter and the internal diameter than the inner diameter of the retainer, By locking the other end of the retainer in the axial direction, and an annular member that is locked in the axial direction by the snap ring and that comes into contact with the piston at a smaller diameter than the inner diameter of the retainer. Even when the piston is changed to one having a smaller outer diameter, the annular member can reliably contact the outer periphery of the piston for positioning, and the piston can be positioned reliably. Adjustment is easy, and the piston can be changed to one having a different outer diameter.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional configuration diagram of a hydraulic servo device that operates a band brake.
FIG. 2 is a cross-sectional configuration diagram of a conventional hydraulic servo device.
[Explanation of symbols]
3 Direct clutch drum 4 Band brake 5 Piston shaft 6 Piston 7 Nut 8 Piston retainer 9, 10 Snap ring 11 Case member 12 Annular member 13 Retainer 14 Return spring 15 Cylinder chamber 16 Hydraulic servo device 17 First hydraulic chamber 18 Second hydraulic pressure Room

Claims (1)

A hydraulic servo device for an automatic transmission that engages and releases a band brake provided on an outer periphery of a clutch drum of an automatic transmission with respect to the clutch drum,
A cylinder chamber provided in the case member;
A piston slidably provided in the cylinder chamber and having a piston shaft;
A first hydraulic chamber that is provided on one end of the piston and moves the piston in a band brake release direction when hydraulic pressure is supplied;
A second hydraulic chamber provided on the other end side of the piston and moving the piston in the direction of fastening the band brake by supplying hydraulic pressure;
A piston retainer disposed opposite to the piston and sealing the second hydraulic chamber;
In a hydraulic servo apparatus for an automatic transmission , which is fitted to the case member and includes a snap ring for positioning the piston,
One end of the axial direction is locked to the inner wall of the case member, and the retainer has an inner diameter corresponding to the outermost diameter of the piston,
The retainer has an inner diameter that is smaller than the inner diameter of the retainer, engages the other end of the retainer in the axial direction, and is retained in the axial direction by the snap ring, and has a smaller diameter than the inner diameter of the retainer. A hydraulic servo apparatus for an automatic transmission , comprising: an annular member that contacts the piston at a portion .

Images