JPH088930Y2 - Fluid actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Field of the Invention The present invention relates to a fluid actuator, and more particularly to a seal structure for a fluid actuator using a piston.

b. Prior Art FIGS. 8 to 9 show a part of a master cylinder as a main part of a fluid actuator using a piston.

In this master cylinder, the piston guide 2 is arranged in the housing 1, and the piston guide 2 is provided with a hole 3
When not in operation, a passage 4 communicating with an oil reservoir (not shown) through the hole 3 is opened in the pressure chamber 5 when not operating. Further, a through hole 7 is formed in the peripheral wall of the piston 6, and as shown in FIG. 8, with the through hole 7 and the hole 3 of the piston guide 2 aligned, an oil reservoir (not shown) is formed. And the pressure chamber 5 are communicated with each other. Therefore, when the oil in the pressure chamber 5 is insufficient, the oil is supplied from the oil reservoir to the pressure chamber 5.

Furthermore, in this master cylinder, the piston guide 2
An annular seal 8 is attached to the end surface of the pressure chamber 5 side (the left end surface in FIGS. 8 and 9). As shown in FIG. 10, the annular seal 8 has an annular recess 8a on one end surface thereof, an inner annular wall 8b, an outer annular wall 8c, and a flange portion connecting these walls 8b, 8c. 8d and the cross section are almost U-shaped. More specifically, as shown in FIG. 10, the inner annular wall 8b of the annular seal 8 has its tip inclined toward the axial center (toward the inner diameter side) and the flange portion.
8d is in contact with the piston guide 2 and the inner annular wall 8b
Is elastically bent around the root portion 8e of the flange portion 8d, only the tip projection 8f of the inner annular wall 8b is the piston 6
Is in sliding contact with.

Thus, when the piston 6 is pushed into the pressure chamber 5 and the through hole 7 of the piston 6 passes through the annular seal 8, the communication between the through hole 7 and the hole 3 of the piston guide 2 is cut off. Therefore, when the piston 6 is further pushed into the pressure chamber 5, the oil in the pressure chamber 5 is pressure-fed to an actuated device such as a wheel cylinder (not shown).

c. Problems to be Solved by the Invention In such a master cylinder, however, there is a loss stroke, in other words, when the through hole 7 of the piston 6 and the hole 3 of the piston guide 2 are completely blocked by the annular seal 8. It is preferable that each product is almost the same.

In the annular seal 8 of the master cylinder described above, as shown in FIG. 10, when the annular seal 8 is fitted to the piston 6, only the tip projection 8f of the inner annular wall 8b is crimp-engaged with the piston 6. Since it is slid and the portion between the tip projection 8f and the root 8e of the flange 8d is arranged in an inclined shape without contacting the piston 6, the following problems occur. There is.

That is, when the annular seal 8 in the oil swells (expands) when the piston 6 is in the position shown in FIG. 8 or 10, the inner annular wall 8b of the annular seal 8 is moved to the piston 6
There is a possibility that the through hole 7 may be unintentionally blocked by a portion other than the tip projection 8f of the inner annular wall 8b by being pressed against the outer peripheral surface of the. In such a state, residual pressure may be generated in the pressure chamber 5 and the actuated device may malfunction. Further, when the inner annular wall 8b is deformed due to the swelling of the annular seal 8, the timing at which the pressure chamber 5 and the oil reservoir are cut off from each other changes, which causes a change in so-called loss stroke, which causes inconvenience that the operating characteristics differ for each product. Cause

The present invention has been made in view of such an actual situation, and an object thereof is to avoid an inconvenience due to swelling of an annular seal, and to provide an accurate timing of disconnection between a pressure chamber and an oil reservoir, That is, it is to provide a fluid actuator having a constant loss stroke and not varying from product to product.

d. Means for Solving the Problems In order to achieve the above-mentioned object, in the present invention, the pressure chamber is communicated with a reservoir through a through hole formed in the circumferential surface of the piston, and the piston is inwardly of the pressure chamber. Fluid in the pressure chamber by moving the piston to the inside of the pressure chamber by cutting the communication between the pressure chamber and the reservoir by passing the through hole of the piston through the annular seal. In a fluid actuator for pumping to the actuated device, an annular protrusion is formed at one end of the piston sliding surface of the annular seal, and a lip piece extending along the outer peripheral direction of the piston is formed at the other end. ,
Moreover, a flow groove is provided in the lip piece.

e. Action The annular protrusion and the lip piece formed on the inner annular wall of the annular seal will be slidably contacted with the piston at locations separated in the axial direction of the piston, and the through hole of the piston due to the swelling of the annular seal The blockage is prevented and the loss stroke is prevented from changing. Further, the circulation groove formed in the lip piece secures the circulation of the fluid.

f. Embodiment FIG. 1 shows a master cylinder as an actuator according to the present invention. A cylinder housing 11 of the master cylinder 10 includes a body body 12 and a body body.
It is composed of a cap 13 screwed to 12.
Ring-shaped piston guides 14 and 15 are arranged in the cylinder housing 11, and pistons 16 and 17 are inserted into the piston guides 14 and 15, respectively.
The interior of the cylinder housing 11 is divided into two pressure chambers 18 and 19 by the piston guide 15 and the piston 17. The pistons 16 and 17 are guided by sleeves 20 arranged in the pressure chamber 18, respectively. This sleeve 20 is to secure a space as the pressure chamber 18,
The inner peripheral surface is formed in a spline shape, and the pistons 16 and 17 are guided by the protrusions thereof. Further, the pistons 16 and 17 are the pistons 16 and
Springs 21 and 22 arranged between the pistons 17 and between the piston 17 and the body 12 are constantly urged to the right in FIG. Each of these pistons 16 and 17 has a concave portion that opens at the tip, and through holes 23 and 24 are formed in the peripheral walls that form the concave portion, respectively. Holes 25 and 26 are formed in the piston guides 14 and 15 in the radial direction thereof. One end of each of the holes 25 and 26 is opened to a sliding contact surface of the piston 16 and 17, and the other end is a cylinder housing. Passage 2 formed in 11
It is connected to 7,28.

Further, annular seals 29, 30 are attached to the end surfaces of the piston guides 14, 15 on the pressure chambers 18, 19 side. These annular seals 29, 30 have annular recesses 29a, 30a on one end surface thereof as shown in an enlarged view in FIGS. 2 and 3, and the inner annular wall forming these recesses 29a, 30a. 29b and 30b have their tips inclined toward the axial center, and annular protrusions 29d and 30d that extend along the entire circumference along the annulus are integrally formed on the piston sliding contact surface at the tip ends. Further, the recesses 29a, 3
On the inner peripheral surface (piston sliding surface) of the inner annular wall 29b, 30b corresponding to the thick portion of the flange portion 29c, 30c forming the bottom wall of 0a, lip piece portions 29e, 30e extending along the annulus are provided. It is integrally molded. As shown in FIG. 3, the lip pieces 29e and 30e are not formed continuously over the entire circumference of the tip portions of the inner annular walls 29b and 30b, but are formed intermittently at a predetermined interval. ing. That is, a plurality of arc-shaped lip pieces 31 and 32 are integrally formed at the tip ends of the inner annular walls 29b and 30b, and flow grooves 33 and 34 are formed between the lip pieces adjacent to each other. Thus, these annular seals 2
As shown in FIG. 1, FIG. 4 and FIG. 5, 9,30 have annular recesses 29a, 30a directed toward the pressure chambers 18, 19 and flanges 29c, 30c having piston guides 14, 30. It is mounted on the cylinder housing 11 while being in contact with 15.

In this mounted state, as clearly shown in FIG. 4, the annular protruding portion 29d of the annular seal 29 and the lip piece 29e are the pistons.
The outer peripheral surface of the piston 16 is pressed against the outer peripheral surface of the piston 16 at positions separated from each other along the axial direction (stroke direction) of the piston 16, and the inner annular walls 29b are arranged to face each other in a substantially parallel manner apart from the outer peripheral surface of the piston 16. Thus, the inner annular wall 29b, the annular protrusion 29d, the lip piece 29e, and the piston 16 form a chamber 36 that extends in an annular shape. Furthermore, as shown in FIG. 3, with respect to the radial cross section of the piston 6 and the annular seal 29, an opening 37 is formed by the piston 16 and the flow groove 33 of the annular seal 29. And a passage for fluid such as oil is formed.

Although not shown, the annular seal 30 also has the same configuration as described above.

Next, the operation of the master cylinder 10 described above will be described with reference to FIGS. 6 and 7. However, in FIG. 6, only the one piston 16, the piston guide 14, the annular seal 29, etc. are shown, but the other piston 17, the piston guide 15, the annular seal 30, etc. also perform the same operation. Then, the description is omitted.

FIG. 6 shows the non-operating state of the piston 16, that is, the standby state. In this state, the through hole 23 of the piston 16
Is located at the center of the hole 25 of the piston guide 14, and the pressure chamber 18 is communicated with an oil reservoir (not shown) through the through hole 23, the hole 25, and the passage 27. Therefore, in this state, hydraulic pressure is not acting on the actuated device (not shown).

Now, when the piston 16 is pushed into the pressure chamber 18, the through hole 23 moves leftward in FIG. Along with this, the through hole 23 passes through the lip piece portion 29e of the annular seal 29 and moves toward the protruding portion 29d of the inner annular wall 29b, but the through hole 23 reaches the protruding portion 29d. Up to, the pressure chamber 18 is connected to an oil reservoir (not shown). That is, in the initial stage, the pressure chamber 18 has a through hole 23, as shown in FIG.
It is communicated with the oil reservoir through the hole 25 and the passage 27, and thereafter, as shown in FIG. 7, the through hole 23, the chamber 36, the flow groove 31 and the gap 50 (the first gap between the inner peripheral surface of the piston guide 14 and the piston 16). 5
(See FIG. 6 and FIG. 6) It is in a state of communicating with the oil reservoir through the hole 25 and the passage 27. Therefore, under such a condition, the oil in the pressure chamber 18 is released to the oil reservoir.

Further, when the piston is pushed into the pressure chamber 18, the through hole
23 reaches the protruding portion 29d of the annular seal 29, and thereafter, the through hole 2
The pressure chamber 18 and the oil reservoir via 3 are disconnected. As a result, the oil in the pressure chamber 18 is sent under pressure to an actuated device such as a wheel cylinder (not shown).

In the above-described master cylinder 10, the protrusion 29d and the lip piece 29e are provided on the inner annular wall 29b of the annular seal 29 so as to serve as a tightening margin for the piston 16. Is held in contact with the piston 16 at a position spaced apart in the axial direction of the piston 16, and even if swelling occurs in a fluid such as oil, the inner annular wall 29b of the annular seal 29 is deformed to form the through hole 23. There is no risk of blockage or variation in lost stroke. On the other hand, the lip piece
Since the flow groove 33 is provided in 29e, the fluid passage is secured.

Although the master cylinder 10 is shown as the actuator in the above embodiment, the present invention is not limited to the master cylinder. An actuator to which the present invention is applied connects a pressure chamber to a reservoir through a through hole formed in a peripheral surface of a piston, moves the piston inward of the pressure chamber, and the through hole of the piston has an annular seal. By disconnecting the communication between the pressure chamber and the reservoir,
Further, the piston is moved inward of the pressure chamber.

g. Effect of the Invention As described above, according to the present invention, the annular protrusion is formed at one end of the piston sliding surface of the annular seal, and the lip piece extending along the outer peripheral direction of the piston is formed at the other end. Since the circulation groove is provided in the lip piece portion, the annular protrusion and the lip piece portion are slidably contacted with the piston. Therefore, even if the annular seal swells, there is no possibility that the annular seal may unintentionally close the through hole of the piston or cause the loss stroke to fluctuate. As a result, it is possible to prevent a situation in which residual pressure is generated in the pressure chambers, and it is possible to obtain a uniform loss stroke between products.

[Brief description of drawings]

1 to 7 show an embodiment of the present invention. FIG. 1 is a sectional view showing a master cylinder as a fluid actuator according to the present invention, and FIG. 2 is a sectional view of an annular seal. FIG. 3 is a side view showing the shape of the inner peripheral portion of the annular seal, FIGS. 4 and 5 are enlarged cross-sectional views of the main parts showing the mounting state of the annular seal, and FIGS. 6 and 7 are master cylinders. Main part enlarged cross section for explaining the action, FIGS.
FIG. 10 shows a conventional master cylinder,
FIG. 9 is a sectional view of a main part of the master cylinder, FIG. 9 is an enlarged sectional view of a main part of the master cylinder, and FIG. 10 is an enlarged sectional view showing a mounting state of an annular seal. 10 ... Master cylinder, 16, 17 ... Piston, 18, 19 ... Pressure chamber, 23, 24 ... Through hole, 29, 30 ... Annular seal, 29a, 30d ... Annular recess, 29b, 30b ... Inner annular part, 29c, 30c … Flange, 20
d, 30d ... Annular protrusion, 29e, 30e ... Lip piece portion, 31, 32 ... Lip piece.

Claims (1)

[Scope of utility model registration request] 1. A pressure chamber is communicated with a reservoir through a through hole formed in a peripheral surface of the piston, the piston is moved inward of the pressure chamber, and the through hole of the piston passes through an annular seal. In the fluid actuator for sending the fluid in the pressure chamber to the actuated device by moving the piston inward of the pressure chamber by disconnecting the communication between the pressure chamber and the reservoir by the piston slide of the annular seal. While forming an annular protrusion on one end of the moving surface,
A fluid actuator characterized in that a lip piece portion extending along the outer peripheral direction of the piston is formed at the other end portion, and a flow groove is provided in the lip piece portion.