JPS6237547A - Band servo device for automatic transmission - Google Patents

Abstract

PURPOSE:To have an impact at the time of band brake clamping as well as to reduce a shift shock, by connecting a stem to a piston relatively slidable via a collar, and setting up a cushion spring between both of them. CONSTITUTION:When hydraulic fluid pressure is fed to a cylinder chamber 25, a piston 21 alone goes up, and upward pressing force of this piston 21 at this time is inputted into a collar 28 via a cushion spring 31, then further transmitted to a stem 20 by this collar 28, pressing this stem 20 upward. With this operation, a movable end 12b of a band 12 moves upward, whereby a diameter of the band 12 is contracted, and clamping operation of a brake drum 11 takes place. At this time, since the cushion spring 31 is set up between the piston 21 and the collar 28, an impact at a time when the band 12 is clamped tight is relieved with the cushion spring 31 contracted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a band servo device for engaging and releasing a band brake used in an automatic transmission.

Conventional technology In general, automatic transmissions have multiple sets of planetary gears in 0iR, and various gears can be obtained by appropriately combining and connecting each element of these planetary gears (sun gear, ring gear, pinion gear). The combination of the above-mentioned elements is coupled using hydraulically operated clutches, band brakes, and other fastening elements. The band brake in the back is tightened by the band servo device (
'1. The band servo device is configured to be released, and hydraulic pressure is supplied to the band servo device from a hydraulic pressure control circuit. That is, as shown in FIG. 2, the band servo device 1 has a stem 3 that is slidably attached to the housing 2 side, and a piston is connected to the stem 3 via a threaded portion 4 as a relative position adjustment mechanism. 5 is screwed on. This piston 5 is slidably and tightly fitted into a piston retainer 6 fixed to the housing 2,
By supplying hydraulic fluid into the nolinder chamber 7 formed between the piston retainer 6 and the piston 5,
The piston 5 moves -L in the figure 2 and presses the stem 3 to tighten the band (not shown). 8 is a piston return spring that is compressed between the housing 2 and the piston 5, and 9 is a nut that fixes the adjustment position between the stem 3 and the piston 5.

Problem to be Solved by the Invention (7)However, in the conventional band servo device 1, since the stem 3 is directly screwed onto the piston 5 via the threaded portion 4, Effect 4 - The pressing force is directly transmitted to the band via the stem 3. Therefore, if the pressing force of the piston 5 were to be transmitted directly to the band in this way, a large shock would occur when the band brake is engaged. This results in a shift shock and deteriorates the ride comfort of the vehicle.Therefore, in the past, a band servo device was used.
+,: An accumulator is installed in the passage of the working fluid ratio to be supplied (
In this case, the band servo device is There is a problem in that a shock to engage the band brake may occur in some cases due to a change in the rise of the hydraulic pressure supplied to the band servo device 1. Therefore, the present invention provides a shock mitigation function in the band servo device itself. It is therefore an object of the present invention to provide a hand servo device for an automatic transmission that prevents or significantly reduces band brake engagement shock.

Means for Solving the Problems In order to achieve the above object, the present invention includes a stem that is slidably attached to the housing and supports the movable end side of the hand at one end, and the other end of the stem. In a band servo device for an automatic transmission, the band servo device for an automatic transmission includes a piston for pressing the stem, and a relative position adjustment mechanism for adjusting the relative position between the piston and the stem. A collar is disposed on the stem, a threaded portion is formed between the collar and the stem as a relative position adjustment mechanism, and the collar and the piston are slidably fitted to form a threaded portion between the collar and the piston. It is constructed by arranging a cushion spring.

Operation With the above-described configuration, in the band servo device for an automatic transmission of the present invention, the suppressing force acting on the piston is once input to the collar via the cushion spring, and then is screwed into the collar. The signal is transmitted to the stem, which tightens the band. At this time, if the pressing force when the brake band is fastened exceeds a predetermined load determined by the biasing force of the cushion spring, the excess load will be absorbed by the collar and the piston as they move relative to each other. Absorbed by cushion spring. Therefore, the excessive impact generated when the band brake is engaged is alleviated by the cushion spring.

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

That is, FIG. 1 shows a band servo device 10 for an automatic transmission showing one embodiment of the present invention, in which 11 is a brake drum, 12 is a band that goes around the outer periphery of the brake drum 11, and these brake drums 11. Band brake 1 with band 12
3 is composed. A portion of the band 12 is separated so that the entire band 12 is urged away from the brake drum 11. Therefore, the band 12 expands in its natural state, and a gap δ is provided between it and the brake drum 11 over the entire circumference, and one end of the band i2 (upper part in the figure)
The locking piece 14 is fixedly installed with the fixed end 12a, and
A locking piece 14a is fixed to the other end (lower side in the figure) of the band 12 as a movable end 12b. The fixed end side locking piece 14 is locked to an anchor pin 16 installed in a housing 15 that houses the band brake 13, and the movable end side locking piece 14a is locked to the band servo device 10. It is now possible to do so.

That is, the band servo device 10 has the anchor pin 1
6, and a piston 21 that applies a pressing force to the stem 20. One end (the upper end in the figure) of the stem 20 is connected to the The movable end 12b is supported by being locked to the movable end side locking piece 14a, and the piston 21 is fitted to the other end (lower end in the figure) of the stem 20 via a collar 28, which will be described later. It has become.

Reference numeral 22 denotes a cylindrical piston retainer that is slidably fitted into the four parts 15a formed in the housing 15 via seal rings 23.23a in a liquid-tight manner. 22a and a small diameter portion 22b is formed with a step portion 22c provided below. Also,
The piston 21 is formed approximately along the inner shape of the piston retainer 22, and has a large diameter portion 21a of the piston 21.
is slidably fitted to the large diameter portion 22a of the piston retainer 22 via a seal ring 24, and the small diameter portion 21b of the piston 21 is fitted to the large diameter portion 22a of the piston retainer 22.
The cylinder chamber 25 is a space formed between the lower part of the piston 21 and the step part 22c of the piston retainer 22.

This cylinder chamber 25 is connected to the circumferential groove 25 of the piston retainer 22 through a passage 25a formed in the piston retainer 22.
b, and the hydraulic pressure from a hydraulic pressure control circuit (not shown) is supplied to the cylinder cylinder chamber 25 from the circumference dη25b. A return spring 26 is compressed between the piston 21 and the housing 15, and the return spring 26 presses the piston 21 downward in the figure.

Furthermore, 27 is a snap ring located at the lower end of the piston retainer 22 and fixed to the inner periphery of the recess 15a,
With this snap ring 27, the piston retainer 2
2 is prevented from falling downward. Further, the large diameter portion 21a of the piston 21 is brought into contact with the stepped portion 22c of the piston retainer 22, and the piston 21 is prevented from moving downward from this contact position.

Reference numeral 28 denotes a collar disposed between the stem 20 and the piston 21, and the inside of this collar 28 is connected to the stem 20.
is screwed through a threaded portion 29 formed between the
The collar 28 side is the center hole 2 of the piston 21.
1c in a slidable manner. The collar 28 further protrudes from the lower end of the piston 21, and a snap ring 30 is fixed to this protruding end at the lower end of the piston 21. When the snap ring 30 comes into contact with the piston 21, the collar 28 is prevented from being moved relative to the piston 21 in one direction from the illustrated position.

The center hole 21c of the piston 21 has an extending portion 21 erected upward with a gap δa between the center hole 21c and the inside of the small diameter portion 21b.
d, and the length Q of the center hole 21c is set to be longer. On the other hand, a flange 28a is formed at the upper end of the collar 28, and a cushion spring 31 is compressed between the flange 28a and the bottom surface 21e of the gap δa forming portion. and,
The cushion spring 31, the center hole 21c of the piston 21, and the collar 28 are arranged concentrically and overlapping each other in the axial direction.

32 is screwed into the lower end of the screw of the stem 20 and abuts against the lower end of the collar 28.
It performs the function of a double nut for the threaded part 29 of 8,
By tightening the nut 32, the screwed position of the collar 28 and stem 20 is fixed. Further, a non-circular portion 28b for locking a tool such as a spanner is formed at the lower end of the snap ring 30 of the collar 28, and a tool is inserted into the lower end of the stem 20 to tighten the stem 20. A square hole 20a for filtering is formed.

With the CD configuration described above, in the band servo device 10 of the automatic transmission of this embodiment, the piston 21 is connected to the hydraulic pressure control circuit.
．． When hydraulic pressure is supplied to the cylinder chamber 25 between the piston retainers 22, the piston retainer 22 is raised while being engaged with the snap ring 27, with only the piston 21 compressing the return spring 26. At this time, The -L direction suppressing force of the piston 21 is applied to the collar 28 via the cushion spring 31, and the collar 28
1, which is transmitted to the stem 20 and presses the stem 90 upward. Then, the movement of the band 12 +, +, rn i
2b, when the locking piece 14a is pressed against the stet 20 in 11fj, the IY of the one-way IJ movement 1-, B/D 1; is compressed, and the brake drum 11 is tightened. As a result, the band brake 13 is engaged.

At this time, since a cushion spring 31 is disposed between the piston 21 and the collar 28, the band 12
The impact when it is tightened by Plagidrano 1.11 is,
It is relieved by compressing the cushion spring 31. Incidentally, this deformation of the cushion spring 31 is made possible by the collar 28 sliding downward relative to the piston 21. By the way, between one end of the extended center hole 21C of the screw I/N 21 and the lower end of the flange 28a of the collar 28, there is a space necessary for shock absorption.
'A M'j Deformation of spring 31 ζX
A gap δb corresponding to the above is set, and when the band 12 is tightened, the rear end spring link 31 is deformed, and the screw I/n 21 is further raised, and the upper end of the center hole 21c is tightened. After abutting against the lower end of the flange 28a, the piston 21
The stem 20 is pressed by the pressing force acting on the stem 20, so that the band brake 13 is securely fastened (-11).

In addition, when releasing the engagement of the brake throat 13,
By removing the hydraulic pressure from the chamber 25, the piston 2
1 is lowered by the biasing force of the return spring 26, the stem 20 is lowered accordingly, and the tightening of the band 12 is released.

By the way, when the band brake 13 is released from engagement,
The initial setting value of the gap δ between the brake drum 11 and the band 12 is a problem, but in this embodiment, the nut 32 screwed onto the stem 20 is first loosened, and the non-circular shape of the collar 28 is Insert tools into the section 28b and the square hole 20a of the stem 20, and rotate the stem 20 to raise it by 1.

After the band 12 is tightened to a specified torque, the stem 20 is returned to the opposite direction by a specified number of rotations. At this time, the resulting gap δ becomes the initial setting value, and in this state the relative position of the stem 20 and collar 28 is fixed by tightening the deaf nut 32.

In this embodiment, since the center hole 21c of the piston 21 is extended to increase its length Q, the piston 21
．． There is no strain caused by relative sliding between the collars 28, and smooth operation is always performed. In addition, since the cushion spring 31, the center hole 21c, and the collar 28 are arranged concentrically and overlapping each other in the axial direction, the length in the central axis direction of the band servo device IO can be shortened, and the device can be made smaller.

As described in detail, in the band servo device for an automatic transmission of the present invention, the stem and piston are connected via a collar so as to be able to slide relative to each other, and a spring is inserted between them. Because of this arrangement, the impact when the throat brake is engaged can be absorbed by the deformation of the cushion spring. Therefore, the shift shock can be significantly reduced, and the accu-z provided in the hydraulic pressure supply path,
, Chew for shock relief in combination with L-・-ta etc.
This has an excellent effect in that the cutting width can be expanded with ease.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a band servo device of the present invention, and FIG. 2 is a cross-sectional view of a main part of a band servo device of IIL Song Dynasty. 10... Band servo device, 11... Brake drum, 12... Band, 13... Band brake, 1
5... Housing, 20... Stem, 21... Piston, 28... Collar, 29... Threaded portion (relative position adjustment mechanism), 31... Cushion spring. 2 people outside

Claims (1)

[Claims] (1) A stem that is slidably attached to the housing and supports the movable end side of the band at one end, a piston that is provided at the other end of the stem and presses the stem, and a combination of the piston and the stem. In a band servo device for an automatic transmission having a relative position adjustment mechanism provided between the stem and the piston, a collar is disposed between the stem and the piston, and a relative position adjustment mechanism is provided between the collar and the stem. A band servo device for an automatic transmission, characterized in that a threaded portion is formed, the collar and the piston are slidably fitted, and a cushion spring is disposed between the collar and the piston.