JPH0578681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an accumulator in an automatic transmission mounted on an automobile, and more particularly to a fixing structure between a piston and a spring in the accumulator.

(B) Prior art Generally, an automatic transmission has a planetary speed change gear mechanism, and a clutch or a brake (frictional engagement element) engages or locks a predetermined element of the speed change gear mechanism to achieve a desired speed. It is configured to obtain the following gears. And these clutches or brakes are
It is controlled by a hydraulic servo that supplies or drains hydraulic pressure by switching the shift valve, but an accumulator is installed in parallel with the hydraulic servo, and based on the hydraulic characteristics of the accumulator, the servo pressure of the hydraulic servo The engagement characteristics of the clutch and brake are determined.

In addition, for a predetermined accumulator, for example, an accumulator for a second brake that operates in 2nd gear, a disc spring or a spring with a natural length shorter than the piston stroke is installed on the accumulator chamber side, and a disc spring is installed only at the piston stroke start portion. It is preferable to use a spring or a spring to obtain predetermined accumulator characteristics (see, for example, Japanese Utility Model Application No. 146101/1983).
In this case, if a disc spring is used, its stroke,
The degree of freedom in load capacity and elastic modulus is small, and it is extremely difficult to set the desired hydraulic characteristics.Furthermore, when a coil spring is used to fix the spring to the housing side, the spring tends to tilt, and in the tilted state. If the piston makes contact, the piston will not be able to move to the lower end of its stroke, and there is a risk that a large shift shock will occur.

(C) Problems to be Solved by the Invention Therefore, the present applicant has developed an accumulator in which a spring is fixed to a piston by caulking, a bolt, or a spring tightening margin, thereby preventing the spring from tilting and improving ease of assembly. has been proposed (published at the end of Patent Application No. 168058/1983).

Incidentally, in recent years, automatic transmissions have been used even in small-horsepower automobiles, and automatic transmissions themselves have been required to be downsized due to the shift to F/F (front engine/front drive). something is required.

In such devices, it is extremely difficult to fix the spring by caulking or bolts, etc., as the inner diameter of the spring is small, and the spring tends to tilt during fixation. In press-fitting using a spring tightening margin, the spring easily comes off, and if the tightening margin is increased to prevent the spring from coming off, it becomes difficult to press-fit the spring.

Furthermore, with the above-described fixing means such as caulking, bolts, press-fitting, etc., the fixed portion is relatively large, and it is necessary to form a large recess in the piston so that the fixed portion does not interfere with the housing. Then,
Normally, in an accumulator that is used with the piston facing upward, air accumulates in the above-mentioned piston recess located at the top of the accumulator chamber, and the air reservoir formed by the recess occupies a relatively large volume with respect to the accumulator chamber, so that the accumulator characteristics are desired. It deviates from the characteristics and changes significantly, causing a shift shock.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an accumulator that can easily and reliably fix a spring to a piston in a small space, thereby solving the above-mentioned problems.

(d) Means for solving the problem The present invention has been made in view of the above circumstances, and as shown in FIGS. 1 and 2, the piston 1 is
On the end surface 1a of the
A concave spring fixing portion 2 is formed.
Further, an expanded diameter portion 3a having a larger diameter than the small diameter portion 2a of the spring fixing portion 2 is formed at one end of the spring 3. Then, the enlarged diameter portion 3a is connected to the large diameter portion 2.
It is characterized in that the spring 3 is fixed to the piston 1 by fitting into the piston 1.

In particular, it is located in the accumulator chamber 5 and has a natural length shorter than the stroke of the piston 1,
It is preferable to apply this to the spring 3 that acts at the stroke start portion of the piston 1 in opposition to another spring 6 contracted at the other end of the piston.

(e) Effect Based on the above configuration, pressure oil is supplied to the accumulator chamber 5 of the accumulator A via the oil passage 7 when pressure oil is supplied to a predetermined engagement element based on switching of the shift valve. Then, the engagement characteristics of a predetermined engagement element are adjusted according to the hydraulic pressure acting on the back pressure side spring 6, the back pressure chamber 9, the capacity of the accumulator chamber 5, the predetermined accumulator characteristics based on the spring 3, etc., and the engagement characteristic of the predetermined engagement element is adjusted smoothly. engage.
Similarly, when the predetermined engagement element is released, the pressure oil in the accumulator chamber 5 is drained from the oil passage 7, and the spring 3 contacts the valve body 10 at the lower end of the stroke of the piston 1, and the predetermined engagement is performed based on the accumulator characteristics. Adjust the release of elements.

Also, when assembling, for example, the spring 3
As shown in FIG. 3, the spring 3 can be easily attached to the end surface of the piston 1 by tilting the spring 3 and pushing it in the direction of the arrow based on the tapered surface 2c of the spring fixing part 2.

Further, even if air accumulates in the accumulator chamber 5 due to use, the concave portion serving as the spring fixing portion 2, which serves as the air reservoir, is relatively small and does not significantly affect the accumulator characteristics.

(F) Embodiments Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

The second brake accumulator A is the first
As shown in the figure, it has a housing 11 that forms a cylinder chamber 11a, and the housing 11 is attached to the valve body 10 by appropriate means. Also, the piston 1 is in the cylinder chamber 11a.
The rings 12 and 13 are slidably fitted in an oil-tight manner, and an accumulator chamber 5 is formed between the end surface 1a of the piston and the valve body 10. A back pressure chamber 9 is formed between the housing 11 and the housing 11 .
Further, an oil passage 7 via an orifice 15 is communicated with the accumulator chamber 5, and the oil passage 7
is in communication with the shift valve and the engagement element (second brake), and the back pressure chamber 9 is in communication with an oil passage 16 extending from the accumulator control valve. Further, a spring 6 is compressed between the other end of the piston 1 and the bottom surface of the housing 11, and the spring 6 always urges the piston 1 toward the accumulator chamber 5. Note that the hole 17 formed in the bottom surface of the housing is an air communication hole.

As shown in detail in FIG. 4, the end surface 1a of the piston 1 is formed with a concave spring fixing part 2, and the spring fixing part 2 has a tapered surface 2c whose diameter gradually becomes smaller from the end surface 1a. It consists of a small diameter portion 2a and a large diameter portion 2b that widens at the back side of the small diameter portion 2c. Further, the spring 3 fixed to the fixed part 2 is made of a coil spring whose natural length is shorter than the piston stroke, and has an expanded diameter part 3a whose diameter is expanded by one turn at one end. Then, if the diameters of the small diameter part 2a and the large diameter part 2b of the fixed part 2 are B and C, respectively, and the diameters of the normal diameter and expanded diameter part 3a of the spring 3 are D and E, respectively, then D<B<E Set the relationship such that <C.

Then, as shown in FIG. 3, the spring 3 is placed diagonally along the tapered surface 2c so that a part of the enlarged diameter part 3a enters the fixed part large diameter part 2b, and in this state is pressed from the direction of the arrow. Or, by slightly twisting and pressing, the enlarged diameter portion 3a passes over the small diameter portion 2a and fits into the large diameter portion 2b. Thereby, the spring 3 is attached to the fixed part 2 of the piston 1, and is reliably prevented from coming off once its expanded diameter part 3a is hooked on the fixed part small diameter part 2a.

Note that the diameter C of the large diameter portion 2b of the fixed portion is determined by the spring 3.
If the diameter is set to be equal to or slightly larger than the diameter E of the expanded diameter portion 3a (C≦E), the spring 3 will be fixed more reliably, and the inclination of the spring will be more reliably prevented, thereby preventing interference between the spring 3 and the housing 11. can be prevented.

In addition, the expanded diameter portion 3a of the spring 3 is shown in FIG.
As shown in FIG. 5, it is possible to simply configure one turn with a large diameter, but as shown in FIG. It may also be possible to prevent the end a of 3 from damaging the fixing part 2 and causing burrs or the like.

Furthermore, as shown in FIG. 5c, the spring enlarged diameter portion 3a is configured in an elliptical shape in which the minor diameter portion has approximately the same diameter as the normal coil diameter, and the elliptical elliptical portions (protruding portions) b, b. ' may be fitted into the fixed part large diameter part 2b, or as shown in FIG.
Constructed in a triangular shape that protrudes radially outward at certain points,
The protrusions c, c', c'' may be fitted into the large diameter portion 2b of the fixed part. In this case, one of the protrusions b or c,
c' is inserted into the large diameter part 2b first, and the remaining protruding part b' or b'' of the remaining cylinder is pushed into the large diameter part 2b, so that the remaining protruding part b' or c'' can be easily removed. Due to the radially inward bending, the spring can be installed very easily.

(G) Effects of the Invention As explained above, according to the present invention, the enlarged diameter portion 3a of the spring 3 having a larger diameter than the small diameter portion 2a of the spring fixing portion 2 is located further back than the small diameter portion 2a. Since the spring 3 is fixed to the end face of the piston by fitting into the large diameter portion 2b, it is extremely easy to install, but once installed, it will not come off, and the fixing part 2 for installation is extremely easy. It has a simple structure and requires only a small amount of space.

Furthermore, if the spring 3 is located in the accumulator chamber 5 and has a natural length shorter than the stroke of the piston 1, the spring 3
The spring 3 prevents the housing 11 from tilting.
It is possible to maintain smooth movement of the piston 1 by eliminating interference with the piston 1, and the concave part of the spring fixing part 2 that serves as an air reservoir can be made small, so that even if air accumulates during use, the air It is possible to always maintain the set accumulator characteristics by reducing the influence of

Further, by bending the enlarged diameter side end a of the spring 3 in the radially inward direction, it is possible to prevent scratches and burrs from occurring when the spring is attached.

Further, by forming a tapered surface 2c between the piston end surface 1a and the small diameter portion 2a, the diameter of which gradually decreases from the piston end surface toward the small diameter portion, attachment of the spring 3 becomes extremely easy.

Further, if the expanded diameter portion 3a of the spring is composed of a plurality of protrusions b and c that protrude radially outward, the spring 3 can be more easily attached and difficult to come off.

[Brief explanation of drawings]

FIG. 1 is a diagram showing different left and right states of the accumulator according to the present invention along the center line, FIG. 2 is an enlarged sectional view showing a spring fixing part, and FIG. 3 is an enlarged sectional view showing a state in which a spring is attached. .
FIG. 4 is an exploded view showing the spring and piston, and FIGS. 5 a to 5 d are plan views showing the enlarged diameter portion of the spring, respectively, showing different embodiments. DESCRIPTION OF SYMBOLS 1... Piston, 1a... End surface, 2... Spring fixing part, 2a... Small diameter part, 2b... Large diameter part,
2c...Tapered portion, 3...Spring, 3a...
Expanded diameter section, 5... Accumulator chamber, A... Accumulator, B... Small diameter section diameter, E... Expanded diameter section diameter, a
... end, b, c... protrusion.

Claims (1)

[Scope of Claims] 1. In an accumulator comprising a piston that is slidably inserted into a cylinder chamber and a spring that biases the piston, an end surface of the piston is provided with a small-diameter portion and a rear side with a large diameter portion. forming a concave spring fixing part that serves as the spring fixing part, and forming an enlarged diameter part having a larger diameter than the small diameter part of the spring fixing part at one end of the spring;
An accumulator configured by fitting the expanded diameter portion into the large diameter portion and fixing the spring to the piston. 2. The accumulator according to claim 1, wherein the spring is located in the accumulator chamber and has a natural length shorter than the stroke of the piston. 3. The accumulator according to claim 1, wherein the space between the piston end face and the small diameter part in the spring fixing part is formed by a tapered surface whose diameter gradually becomes smaller from the piston end face toward the small diameter part. 4. The accumulator according to claim 1, wherein the expanded end of the spring is bent in a radially inward direction. 5. The accumulator according to claim 1, wherein the expanded diameter portion of the spring comprises a plurality of protrusions that protrude in a radially outward direction.