JPH0439091Y2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field The invention relates to a fluid actuator.
Specifically, the present invention relates to a seal structure for a fluid actuator using a piston.

b. Prior Art FIGS. 4 and 5 show a part of a master cylinder as a main part of a fluid actuator using a piston.

In this master cylinder, a piston guide 2 is disposed in a housing 1, and a hole 3 is bored in the piston guide 2. A passage 4 communicates with an oil reservoir (not shown) through the hole 3 when not in operation.
is opened into the pressure chamber 5. Further, the piston 6 has a through hole 7 formed in its peripheral wall, and as shown in FIG. and the pressure chamber 5 are communicated with each other. Therefore,
When the oil in the pressure chamber 5 becomes insufficient, oil is supplied from the oil reservoir to the pressure chamber 5.

Furthermore, in this master cylinder, an annular seal 8 is attached to the end surface of the piston guide 2 on the pressure chamber 5 side (the left end surface in FIGS. 4 and 5). 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, 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 becomes
It is fed under pressure to an actuated device such as a wheel cylinder (not shown).

c. Problems to be solved by the invention By the way, in such a master cylinder, there is a loss stroke, in other words, when the passage hole 7 of the piston 6 and the hole 3 of the piston guide 2 are completely blocked by the annular seal 8. However, it is preferable that each product be substantially the same.

However, in the conventional master cylinder, as shown in FIG.
In particular, when passing through the middle thick part 8a of the annular seal 8, the oil increased in pressure within the pressure chamber 5 pushes the annular seal 8 wider as shown by the arrow, and widens the gap between the piston guide 2 and the piston 6. It may flow out into the hole 3 through the process. Inner annular portion 8b of annular seal 8
Since the pressure within the pressure chamber 5 acts on the outer periphery of the piston 6, when the through hole 7 of the piston 6 passes the intermediate thick portion 8a of the annular seal 8, the outflow of the oil is almost stopped. Therefore, in order to accurately set the loss stroke, the intermediate thick portion 8 of the annular seal 8 must be
It is possible to reduce the thickness of the annular seal 8, but this may weaken the annular seal 8 and reduce the sealing effect.

An object of the present invention is to provide an actuator in which the timing at which the pressure chamber and the reservoir are shut off is accurate, that is, the loss stroke is constant, and there is no variation from product to product.

d Means for Solving the Problems The fluid actuator of the present invention communicates a pressure chamber with a reservoir through a through hole formed on the circumferential surface of a piston, moves the piston inward of the pressure chamber,
The passage hole of the piston passes through the annular seal, thereby cutting off communication between the pressure chamber and the reservoir, and further moving the piston inward of the pressure chamber, thereby removing the fluid within the pressure chamber. A fluid actuator that pumps fluid to an actuated device, wherein the annular seal has an annular notch extending between an end surface of the annular seal opposite to the pressure chamber side end surface and a part of the sliding surface of the piston. and a ring having a cylindrical portion extending in the direction of movement of the piston and a flange-like portion extending in a direction perpendicular to the direction of movement of the piston, the cylindrical portion of the ring being inserted into the annular notch of the annular seal. The annular seal and the ring are arranged such that the annular seal is fitted into the annular seal and the flange of the ring is brought into contact with the opposite end surface of the annular seal.

e Effect: In other words, in the fluid actuator of the present invention, the sliding surface of the annular seal corresponding to the intermediate thick portion of the piston is cut out, and the cylindrical portion of the ring is interposed therebetween. The fluid in the pressure chamber is actively vented to the reservoir as the through hole passes through, eliminating unstable areas of the seal.

f Embodiment FIG. 1 shows a master cylinder as an actuator according to the present invention, FIG. 2 shows each part of its sealing part, and FIG. 3 shows the sealing action.

A cylinder housing 11 of this master cylinder 10 is composed of a body body 12 and a cap 13 screwed onto the body body 12. Inside the cylinder housing 11, ring-shaped piston guides 14 and 15 are arranged. Pistons 16 and 17 are inserted through these piston guides 14 and 15, respectively. The piston guide 15 and the piston 17 create two pressure chambers 1 inside the cylinder housing 11.
8 and 19. the piston 16,
17 is a sleeve 20 disposed within the pressure chamber 18
They are also guided by. This sleeve 20 has an inner circumferential surface formed in a spline shape in order to secure a space for the pressure chamber 18, and the pistons 16, 17 are guided by the protrusion 20a. Furthermore, an annular notch 20b is formed on the inner circumferential surface of the end of the sleeve 20, and an annular seal, which will be described later, is held by this notch. The pistons 16 and 17 are urged to the right in FIG. 1 by springs 21 and 22 disposed between the pistons 16 and 17 and between the piston 17 and the body main body 12 . These pistons 16 and 17 have a recess opening at the tip, and a through hole 2 is formed in the peripheral wall forming the recess.
3 and 24 are drilled respectively. The piston guides 14 and 15 have holes 2 in their radial direction.
5, 26 are drilled, and those holes 25, 2
One end of the cylinder 6 is open to the sliding surfaces of the pistons 16 and 17, and the other end is communicated with passages 27 and 28 formed in the cylinder housing 11. Seal assemblies 29 and 30 are attached to the end faces of these piston guides 14 and 15 on the pressure chambers 18 and 19 side. These seal assemblies 29, 30
As shown in an enlarged view in FIG. 2, it is composed of annular seals 31 and 32 and rings 33 and 34 made of hard synthetic resin, metal, or the like.
The annular seals 31 and 32 have an annular recess 31 on one end surface.
a, 32a, and the inner circumferential surfaces (piston sliding surfaces) of the inner annular portions 31b, 32b forming the recessed portions are provided with a notch 3 in which a part of the inner circumferential surface is cut out.
1c and 32c are formed. This notch 31
c, 32c reach the other end surface, and the notch 31
The axial length of c, 32c is the annular recess 31a, 3
The thickness is larger than that of the intermediate thick portions 31d and 32d forming the portion 2a. On the other hand, ring 33,
34 has an L-shaped cross section, that is, cylindrical portions 33a and 34a.
and brim-shaped parts 33b, 34b, and cutouts 33c, 34c extending in the axial direction are formed on the inner peripheral surfaces thereof. As shown in FIG. 1, such seal assemblies 29, 30,
The rings 33 and 34 are installed so that their other end surfaces are in contact with the end surfaces of the piston guides 14 and 15, and the annular seals 31 and 32 are provided with their notches 31c and 34, respectively.
32c to the cylindrical parts 33a, 34 of the rings 33, 34.
It is installed to match a. In FIG. 1, reference numeral 35 indicates an oil reservoir, and the oil reservoir 35 is fixedly installed in the cylinder housing 11, and passages 36 and 37 bored at the bottom of the oil reservoir 35 are connected to the cylinder housing 11. They communicate with passages 27 and 28, respectively. Further, symbols 38 and 39 are holes bored in the cylinder housing 11, and these holes 38,
The pressure chambers 18 and 19 are communicated with an actuated device (not shown), for example, a wheel cylinder, through the pressure chamber 39.

The operation of the master cylinder 10 described above will be explained below with reference to FIG. However, in FIG. 3, one piston 16, the piston guide 14,
Only the seal assembly 29 etc. are shown, but the other piston 17 and piston guide 1
5. The seal assembly 30 and the like perform the same function, so their explanation will be omitted here.

FIG. 3a shows the piston 16 in its inactive or standby state. In this state, the through hole 23 of the piston 16 and the hole 25 of the piston guide 14 communicate with each other, and the pressure chamber 18 communicates with the oil reservoir 35 via the through hole 23, the hole 25, and the passage 27. Therefore, in this state, no hydraulic pressure is acting on the actuated device (not shown).

Now, when the piston 16 is pushed into the pressure chamber 18, the through hole 23 also moves to the left in FIG.
However, until the through hole 23 reaches the sliding surface of the annular seal 31 with the piston 16, as shown in FIG.
c, inner peripheral surface of piston guide 14 and piston 16
It communicates with the hole 25 through a gap between the two. Therefore, the oil in the pressure chamber 18 is reliably released to the hole 25 as shown by the arrow.

Further, when the piston 16 is pushed into the pressure chamber 18 , the through hole 23 opens the piston 1 of the annular seal 31 .
It reaches the sliding surface with 6. In such a state, the pressure within the pressure chamber 18 acts to expand the annular seal 31 through the through hole 23;
Since the internal pressure also acts on the outer peripheral surface of the inner annular portion 31b of the annular seal 31, the through hole 23 is almost certainly closed.

Then, the piston 16 is further pushed in, and the third
As shown in Figure c, the through hole 23 is connected to the annular seal 31.
When passing through, the through hole 23 and the hole 25 are completely blocked off. Therefore, from then on, the piston 16
An amount of oil corresponding to the pushing amount is supplied from the pressure chamber 18 to an actuated device (not shown).

In addition, although the master cylinder 10 was shown as an actuator in the said Example, this invention is not limited to a master cylinder. An actuator to which the present invention is applied communicates a pressure chamber with a reservoir through a through hole formed on the circumferential surface of a piston, moves the piston inward of the pressure chamber, and connects the through hole of the piston with an annular seal. A fluid actuator that cuts off communication between the pressure chamber and the reservoir by passing through the pressure chamber, and further moves the piston inward of the pressure chamber to forcefully feed the fluid in the pressure chamber to the actuated device. That's fine.

g. Effects of the Invention As described above, in the fluid actuator according to the present invention, by holding the annular seal with a ring, the area where the sealing action is unstable is reduced.

Therefore, in the fluid actuator according to the present invention, uniform loss stroke can be obtained between products.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a master cylinder as a fluid actuator according to the present invention, Fig. 2 is an exploded cross-sectional perspective view of parts constituting the seal portion of the master cylinder, and Fig. 3 is a cross-sectional view of the master cylinder. 4 is a sectional view showing a seal portion of a conventional fluid actuator, and FIG. 5 is an enlarged sectional view of a main part of the seal portion. 10... Master cylinder, 11... Cylinder housing, 14, 15... Piston guide, 1
6, 17... Piston, 18, 19... Pressure chamber,
23, 24... through hole, 25, 26... hole, 27,
28... Passage, 29, 30... Seal assembly, 31, 32... Annular seal, 31a, 32a
...Annular recessed part, 31b, 32b...Inner annular part,
31c, 32c...notch, 31d, 32d...
Intermediate thick part, 33, 34...Ring, 33a, 3
4a... Cylindrical part, 33b, 34b... Flange-shaped part, 3
3c, 34c... Notch, 35... Oil reservoir, 36, 37... Passage, 38, 39... Hole.

Claims (1)

[Scope of utility model registration request] The pressure chamber is communicated with the reservoir through a through hole formed in the circumferential 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, thereby reducing the pressure. In the fluid actuator, the fluid in the pressure chamber is pressurized to the actuated device by cutting off communication between the chamber and the reservoir and further moving the piston inward into the pressure chamber, the annular seal having an annular An annular notch is formed that spans the end surface of the seal opposite to the pressure chamber side end surface and a part of the sliding surface of the piston, and a cylindrical part that extends in the direction of movement of the piston and a part that extends in the direction of movement of the piston. a ring having a flange-like part extending in a direction perpendicular to the annular seal, the cylindrical part of the ring is fitted into the annular notch of the annular seal, and the opposite end face of the annular seal is provided with the ring. A fluid actuator characterized in that the annular seal and the ring are arranged so that the brim portion is in contact with the ring.