JPH0366521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an accumulator used, for example, in a hydraulic circuit of an automatic transmission for an automobile, and particularly to a piston seal structure thereof.

(Prior Art) As a conventional hydraulic circuit accumulator, the one shown in FIG. 2 is known, which is in use in, for example, the 3N71B transmission manufactured by Nissan Motor Co., Ltd. This accumulator is used in the hydraulic circuit of an automobile transmission, and a piston 3 is accommodated in a retainer 2 that is integrally formed with a transmission case.
4 to seal. Further, the piston 3 is biased in one direction by the mechanical spring 6, and among the hydraulic chambers 7, 8, and 9 defined between the retainer 2 and the piston 3, the hydraulic chamber 7 is connected to the hydraulic chamber 7 through a hydraulic passage (not shown). Hydraulic chamber 8 supplies hydraulic pressure for the hydraulic actuator.
is connected to a drain, and the hydraulic chamber 9 supplies bias pressure to the hydraulic chamber 7.

(Problem to be Solved by the Invention) However, in such a conventional seal structure of an accumulator, since both large-diameter and small-diameter seals are provided on the piston side of the accumulator, there is no space for storing the seals on the piston side. This limits the diameter of the spring installed in the small diameter end of the piston, and limits the spring capacity.

An object of the present invention is to solve the above-mentioned problem by arranging the seal on the small diameter side on the retainer side instead of on the piston.

In this case, the span between the large-diameter side seal and the small-diameter side seal, the so-called seal span, changes as the piston strokes, and if the seal span is small when the mechanical spring seated on the piston is compressed, the spring will be biased. It is difficult to suppress the tilting of the piston due to force, resulting in galling between the piston and the seal.

The object of the present invention is to provide an accumulator seal structure that solves this problem.

(Means for Solving the Problems) For this purpose, the present invention provides a stepped piston whose outer periphery is composed of a large diameter part and a small diameter part, and a piston in which the large diameter part and the small diameter part are slidably fitted into each other. A retainer having a stepped inner peripheral surface having a large diameter portion and a small diameter portion that match each other, and a sealed chamber between the piston and the retainer by sealing the large diameter portions and the small diameter portions of the piston and the retainer. In the accumulator, the seal sealing between the large-diameter portions is provided with a mechanical spring that is arranged to penetrate through the small-diameter side end of the piston and urges the piston in the axial direction. A seal is placed on the outer periphery of the large-diameter side of the piston, and a seal that seals between the small-diameter portions is placed on the inner periphery of the small-diameter side of the retainer. It is arranged so that it is compressed as the piston strokes.

(Operation) A predetermined accumulation rate operation can be obtained by the stepped piston, which is applied with a spring, stroking between the retainers.

By the way, since the seal on the large-diameter side is arranged on the piston, and the seal on the small-diameter side is arranged inside the retainer, there is no need to secure a storage space for the latter seal in the small-diameter part of the piston. Therefore, the diameter of the spring disposed through the small diameter portion of the piston is not restricted, and the spring capacity can be kept large.

Also, because of this seal arrangement, even if the seal span changes with the piston stroke, the spring is arranged so that the mechanical spring is compressed as the piston stroke increases in the direction of increasing the seal span, so there is no large spring bias when the spring is compressed. A large seal span can reliably prevent the piston from tilting due to force, and galling between the piston and the retainer can be avoided.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing an embodiment of the accumulator seal structure of the present invention. This embodiment shows an accumulator incorporated in a band servo actuator of an automatic transmission. A servo retainer 40 and an accumulator retainer 41 are fitted into the hole 11 of the automatic transmission case 10, and a snap spring 42 prevents them from coming off. Servo retainer 40
has an outer circumferential groove 43 , and the accumulator retainer 41 has an outer circumferential groove 44 . O-rings 45, 46, 47 are arranged before and after the grooves 43, 44. The large outer diameter portion of the servo piston 48 is fitted into the inner diameter portion 40a of the servo retainer 40, and a seal ring 49 is disposed on the large outer diameter portion of the servo piston 48.

The servo piston 48 is fitted into the stem 53 so as to be able to stroke between a washer 50 attached to the stem 53 and a spring retainer 52, and the servo piston 48 is pressed against the washer 50 by a cushion spring 51 seated on the spring retainer 52. A return spring 54 is further applied to the servo piston 48, thereby urging the servo piston 48 to the right in FIG. The large outer diameter part of the accumulator piston 55 is fitted into the inner diameter part 41a of the accumulator retainer 41, and a seal ring 56 fitted to the large outer diameter part of the accumulator piston 55 is used to connect these parts. Seal.
The small outer diameter part of the servo piston 48 is fitted into the inner diameter part of the accumulator piston 55, and the space between them is sealed by a seal ring 57. Further, the small outer diameter portion of the accumulator piston 55 fits into the inner diameter portion 41b of the accumulator retainer 41, and the space between them is sealed by a seal ring 58 fitted to the inner diameter portion 41b of the retainer.

Incidentally, the accumulator piston 55 is biased to the right in FIG. The accumulator spring is arranged so as to be compressed to a greater extent as the piston 55 strokes to the left in the figure, as the seal span between the seals 56 and 58 increases.

Three oil passages 10a, 10b and 10c are formed in the case 10, the oil passage 10a communicates with an oil chamber 62 defined between the case 10 and the servo piston 48, and the oil passage 10b communicates with the servo retainer 40. groove 43
The oil passage 10c communicates with the oil chamber 63 between the servo piston 48 and the accumulator piston 55 through the oil hole 40b.
The oil chamber 64 between the accumulator retainer 41 and the accumulator piston 55 is communicated through the groove 44 and the oil hole 41c.

The tip of the stem 53 is engaged with a brake band disposed around the outer periphery of a drum of a brake (not shown) so as to apply a fastening force to the brake band.

Next, the action of the accumulator in this band servo actuator will be explained. Oil road 1
0a is connected to a servo release pressure circuit in a shift control device of an automatic transmission, oil passage 10b is connected to a servo apply pressure circuit, and oil passage 10c is connected to a line pressure circuit, so that line pressure is always used as accumulator back pressure. supply

Assuming that the band brake operated by this actuator is to be engaged in the second gear of the automatic transmission, the oil path 1 is closed in the first gear.
Hydraulic pressure is not supplied to 0a and oil passage 10b, and line pressure is supplied only to oil passage 10c. Therefore, in this case, the line pressure in the oil chamber 64 pushes the accumulator piston 55 to the left in FIG. 1 against the spring force of the accumulator springs 60 and 61, and the servo piston 48 is pushed to the right in FIG. 1 to the limit by the return sprick 54. This state is shown in the upper half of FIG.

When the transmission control device switches from this state to the second speed selection state and servo apply pressure is supplied to the oil passage 10b, this oil pressure passes from the groove 43 through the oil hole 40b and acts on the oil chamber 63. Therefore, a force acts on the accumulator piston 55 in the right direction in FIG.
On the other hand, the oil chamber 64 is located in the accumulator piston 55.
A force is applied to the left in Fig. 1 due to the hydraulic pressure acting on the accumulator springs 60, 6.
1 to the right in FIG. 1, and because the pressure receiving area of the oil chamber 63 is larger than the pressure receiving area of the oil chamber 64, the accumulator piston 55 moves toward the right in FIG. Move while extending 60 and 61. Accumulator piston 5
While the accumulator piston 55 is moving, the oil pressure in the oil chamber 63 gradually increases, and after the accumulator piston 55 completes its full stroke, the oil pressure in the oil chamber 63 increases rapidly.

The oil pressure in the oil chamber 63 also acts on the servo piston 48, and the servo piston 48 receives a force to the left in FIG. Since the leftward force acting on the servo piston 48 also changes depending on the oil pressure in the oil chamber 63, the force acting on the band brake (not shown) through the stem 53 also increases gradually at first, and the accumulator piston 55 After finishing the stroke, it increases rapidly. Therefore, the band brake is gradually engaged, and the shift shock during the 1st-2nd shift is alleviated. The force applied to the stem 53 as the accumulator piston 55 moves to the left in FIG.
1, the shock is transmitted while being buffered, and this also makes it possible to further reduce the shift shock.

When shifting to third speed, the band brake is released, and this release is performed as follows. That is, in this case, the servo psi pressure is kept supplied to the oil passage 10b, and in addition, the servo release pressure is supplied to the oil passage 10a. The servo release pressure in the oil passage 10a reaches the oil chamber 62, and the servo piston 4
8, a force is applied to the right side in FIG. Since the oil pressure in the oil chamber 62 acts on the entire surface of the servo piston 48, the servo piston 48 moves to the right in FIG. 1 and the band brake is released, regardless of the servo apply pressure acting on the oil chamber 63. Ru.

In this embodiment, a seal ring 56 provided on the side of the accumulator piston 55 is used to seal the large diameter portion of the accumulator piston 55 as a seal between the accumulator piston 55 and the accumulator retainer 41. By using the seal ring 58 provided on the accumulator retainer 41 side to seal the small diameter portion of the accumulator piston 55, there is no need to secure a storage space for the small diameter portion seal 58 in the small diameter portion of the piston 55.
The inner diameter of the small diameter portion of the piston 55 can be increased accordingly. Therefore, the diameters of the accumulator springs 60 and 61 disposed to penetrate into the small diameter portion of the piston 55 can be increased, and the spring capacity can be increased.

In this seal structure, although the seal span between the seals 56 and 58 changes as the piston 55 strokes, the springs 60 and 61 change as the piston 55 strokes leftward in FIG. 1 in the direction in which the seal span increases. Since these springs are arranged so as to be compressed, a large seal span reliably prevents the piston 55 from tilting due to a large biased spring force when the springs 60 and 61 are compressed, thereby avoiding galling between the piston 55 and the retainer 41. be able to.

(Effects of the Invention) Thus, in the accumulator seal structure of the present invention, as described above, the seal that seals the large diameter parts of the piston and the retainer is on the piston side, and the tail that seals between the small diameter parts is on the retainer side. Since the structure is such that the inner diameter of the small diameter part of the accumulator piston can be increased by the seal space, the diameter of the accumulator spring that is arranged to pass through this small diameter part can also be increased, and the spring capacity can be increased. .

Also, since the spring is arranged so that the accumulator spring is compressed as the piston strokes in the direction of increasing the span between both seals, the compressed state of the accumulator spring changes even when the seal span changes with the piston stroke. It is possible to prevent the piston from tilting by absorbing the large spring bias force in the large seal span, and it is possible to avoid galling between the piston and the retainer.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a band servo actuator to which the accumulator seal structure of the present invention is applied, and FIG. 2 is a sectional view of an accumulator showing a conventional seal structure. 10... Automatic transmission case, 10a, 10
b, 10c...oil path, 40...servo retainer,
41...Accumulator retainer, 45, 46,
47...O ring, 48...Servo piston, 4
9... Seal ring, 50... Washer, 51...
...Cushion spring, 52 ... Spring retainer, 53 ... Stem, 54 ... Return spring, 55 ... Accumulator piston, 5
6, 57, 58... Seal ring, 59... Spring retainer, 60, 61... Mechanical accumulator spring, 62, 63, 64... Oil chamber.

Claims (1)

[Scope of Claims] 1. A piston with a stepped shape whose outer periphery is composed of a large diameter part and a small diameter part, and a large diameter part and a small diameter part in which the large diameter part and the small diameter part are slidably fitted, respectively. a retainer having a stepped inner circumferential surface; a seal that seals between the large diameter portions and between the small diameter portions of the piston and the retainer to form a sealed chamber between the piston and the retainer; In the accumulator, the seal that seals between the large-diameter portions is provided on the outer periphery of the large-diameter portion of the piston. a seal for sealing between the small diameter parts is arranged on the inner periphery of the small diameter part of the retainer, and the spring is arranged so as to be compressed as the piston strokes in a direction in which the span between the two seals increases. The accumulator seal structure is characterized by: