JPH0213808Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealing device for a master cylinder used in a brake or clutch device of an automobile or the like.

The following master cylinders equipped with such a sealing device are known.

For example, FIG. 1 shows a side cross-section of a commonly known tandem master cylinder.

That is, the master cylinder 1 has a cylinder hole 3 bored in the cylinder body 2, a slave piston 4 and a main piston 5 are slidably inserted into the cylinder 3, and a slave pressure chamber is formed on the bottom side of the cylinder hole 3. 6. A main pressure chamber 7 is formed between both pistons 4 and 5.

On the front side of the main piston 5, a return spring 11 whose maximum extension amount is defined by the piston 10 is provided between the retainer 8 and the spring receiver 9, and is integrated with the main piston 5. A return spring 1 having a set tension smaller than the tension of the return spring 11 is provided on the front side of the piston 4 between it and the bottom of the cylinder hole 3.
2 is tensioned and connected to the slave piston 4 via the spring receiver 13.
is biased backwards.

Lip-type seal members 14, 15, 16, and 17 are attached to the front and rear of each piston 4, 5, respectively, to seal the necessary parts.
Replenishment chambers 18 and 19 are formed on the outer periphery of 5, respectively.

Each of the pressure chambers 6 and 7 is connected to two independent pipes via a discharge part (not shown), and each piston 4 and 5 is moved by the tension of a return spring 12.
The main piston 5 comes into contact with the stopper 20 provided at the open end of the cylinder hole 3, and the retainer 8 is displaced as far forward as possible with respect to the main piston 5 due to the tension of the return spring 11, and the displaced retainer 8 becomes the follower piston. When the pressure chambers 6 and 7 are in the so-called return position where the pistons 4 and 4 come into contact, each pressure chamber 6 and 7 has a loosening hole 21 that is located slightly forward of the seal members 14 and 16 on the front side of each piston 4 and 5. , 22 to the recesses 25, 26 of the boss portions 23, 24. Loosen holes 21, 2
2, each seal member 14, 16 is connected to this loosening hole 2.
In order to avoid damage even if the cylinder passes through the openings 1 and 22, the opening at the lower end, in other words, the opening relative to the cylinder hole 3 is made quite small. In addition, each supply room 18,
19 is a flange portion 27, 2 of each piston 4, 5;
It communicates with the rear side of each seal member 14, 16 through a large number of small holes 29, 30 drilled in 8, and communicates with the rear side of each seal member 14, 16 through a large number of small holes 29, 30 formed in
It communicates with recesses 25 and 26 of 24.

Although not shown in detail, the rear end surfaces of each seal member 14, 16 and each flange portion 2
Seal protectors 33 and 3 are provided between the holes 29 and 28 to prevent the small holes 29 and 30 from being bitten.
4 are arranged respectively.

The operation and structure of the master cylinder 1 are well known, but will be briefly explained.

When the brake pedal (not shown) is depressed to move the main piston 5 forward, the tension of the return spring 11 is slightly greater than the tension of the return spring 12, so the master and slave pistons 4 and 5 simultaneously move while compressing the return spring 12. Initially, each sealing member 14, 16 moves to close each loosening hole 21, 22. When each loosening hole 21, 22 closes each loosening hole 21, 22, each sealing member 14, 16 closes each loosening hole 21, 22, pressure starts to be generated in the slave pressure chamber 6, and the slave piston 4 also starts to be generated in the main pressure chamber 7. Pressure begins to be generated so that the pressures that occur before and after are the same, and as pressurized liquid is discharged to each piping system, pressure is generated.

Once the desired pressure is generated and the required brake is applied, stop pressing the brake pedal and remove your foot from the brake pedal.

Then, each piston 4, 5 returns to its initial return position due to the tension of each return spring 11, 12 in response to the release of the pressing force, and the pressurized liquid discharged into the piping system is
A reservoir (not shown) returns to each pressure chamber 6, 7 and is connected to the boss portions 23, 24 from the loosening holes 21, 22.
The pressure is released. At this time, each piston 4, 5 rapidly retreats under the tension of the return springs 11, 12, increasing the volume of each pressure chamber 6, 7, so that negative pressure is generated in each pressure chamber 6, 7. As a result, the outer peripheral lip of each seal member 14, 16 is largely deflected inward of each pressure chamber 6, 7, and the hydraulic fluid in supply chambers 18, 19 flows through small holes 29, 30,
It flows into each pressure chamber 6, 7 through the outer periphery of the seal protectors 33, 34 and the outer periphery of the seal members 14, 16. The total volume of the hydraulic fluid that has flowed in as a result and the hydraulic fluid that has returned from the piping system to each pressure chamber 6, 7 is larger than the volume of each pressure chamber 6, 7 when it is not in operation. Some flow into the reservoir through the holes 21 and 22.

As described above, the ordinary master cylinder 1 is constructed and functions, and the seal members 14, 1
6 especially uses a lip seal, so the pressure chambers 6, 7 are largely moved inward due to the above-mentioned negative pressure or friction with the inner peripheral surface of the cylinder hole 3 when the pistons 4, 5 return. Because of the deformation, at the return position of each piston 4, 5, as shown in FIG. The outer circumferential lip portion deforms forward to form a gap with the flange portions 27, 28 or the seal protectors 33, 34 behind it.

Therefore, in order to prevent the loosening holes 21 and 22 from being closed by the outer peripheral lip portions of the seal members 14 and 16 at the return position, the seal members 14 and 16 are moved forward more than necessary, taking into consideration the deformation of the seal members 14 and 16 at the return position. I try to form it on the side.

This phenomenon also occurs with the seal protector 33,
This will become more noticeable if the outer periphery of the seal member 34 is made to have elasticity and the outer periphery lip side portion of each seal member 14, 16 is positively pressed forward.

In this way, the positions of the loosening holes 21 and 22 for each seal member 14 and 16 may be set to positions that are moved forward more than necessary, or each seal member 1
The formation of a gap on the rear side or the low pressure side of the master cylinder 1 increases the operating play in the master cylinder 1 and increases the length to provide an unnecessary margin. That is, the loosening holes 21 and 22 are connected to each seal member 14 and 16.
Since pressure cannot be generated in both pressure chambers 6 and 7 unless both are closed by
The stroke of each piston 4, 5 until pressure is generated in both pressure chambers 6, 7 becomes operational play. Displacing the seal member 1 more to the front side increases the stroke required to close each loosening hole 21 and 22, and also
4 and 16 on the low pressure side are the respective loosening holes 21 and 22.
Even if the holes 21 and 22 are closed, it is wasted, and the stroke until each loosening hole 21, 22 is substantially closed is increased.

In order to solve the above problem, a coil having a diameter smaller than the inner diameter of the outer lip portion of the seal members 14, 16 and larger than the outer diameter of the inner circumferential portion that fits around the outer circumference of the pistons 4, 5 of the seal members 14, 16 is used. It is conceivable that a spring urges the base portion connecting the outer peripheral lip portion and the inner peripheral portion toward the flange portions 27 and 28 to prevent deformation of the seal members 14 and 16. However, in such a device, there is a risk that the coil spring will be displaced in the radial direction and eccentricity with respect to the base portion. If the coil spring is eccentric with respect to the base part, the seal members 14, 16
, there is a part where the inner circumferential side of the base part is biased, and in such a part, the outer circumferential lip part and the base part are affected by the negative pressure in the pressure chambers 6 and 7 and the inner circumferential surface of the cylinder hole 3. Since the pressure chambers 6 and 7 are deformed inward due to friction, the operating play of the master cylinder also increases.

The present invention has been made in view of these problems, and provides a sealing device for a master cylinder that can reliably prevent the sealing member from deforming inward to the pressure chamber over the entire circumference, thereby reducing the operational play of the master cylinder. In order to achieve this purpose, a cylinder is installed in an annular recess formed in one side of a main body in which a cylinder hole of a master cylinder is formed or a piston that is movably fitted into the cylinder hole. The sealing device for a master cylinder seals a liquid chamber formed, the sealing device comprising: a base portion whose back surface is supported by the side surface of the annular recess; and a bottom surface of the annular recess formed integrally from a part of the base portion. a fitting portion that fits into the base portion and extends toward the liquid chamber; and a lip portion that is integrally formed from the other end of the base portion, extends toward the liquid chamber, and comes into elastic contact with the other of the cylinder hole or the piston. In the master cylinder sealing device, an elastic pressing portion extends in a radial direction along the liquid chamber side of the base portion and presses the base portion toward a side surface of the annular recess;
An auxiliary body is provided which has a cylindrical part that is joined to the fitting part and supports the pressing part.

In other words, even if the base part of the sealing device is deformed toward the liquid chamber due to friction or negative pressure in the liquid chamber, the deformation is prevented by the pressing force of the pressing part of the auxiliary body, and even if it is deformed, the pressing part of the pressing part will not be able to press. Pressure forces it back into place. Furthermore, since the pressing part is supported by the cylindrical part of the auxiliary body joined to the fitting part, it is positioned with respect to the base part. Therefore, the pressing part does not become eccentric with respect to the base part, so
The entire circumference of the base portion is reliably pressed by the pressing portion to prevent deformation and to reduce play during operation of the master cylinder. In addition, even when used to close a loosening hole, the base part is pressed by the pressing part supported by the cylindrical part and deformation is prevented over the entire circumference, so that the lip part is also kept in a predetermined position over the entire circumference. Since the loosening hole does not need to be located at a position more distant from the tip of the lip portion than necessary, the master cylinder can be shortened.

The following description will be made based on the illustrated example. Note that the same reference numerals are given to parts and members having the same functions as in the conventional example, and explanations thereof will be omitted.

FIG. 3 is a partial diagram showing an embodiment of the present invention.

The example shown in FIG. 3 shows an example in which the present invention is applied to a sealing member 14 for sealing the slave pressure chamber 6 of the tandem master cylinder 1 shown in FIGS. 1 and 2.

In FIG. 3, the seal member 40 has the same shape as the previous seal member 14, but has an inner circumferential portion 41 that serves as a fitting portion that tightly fits into the piston 4, and elastically contacts the inner circumferential surface of the cylinder hole 3. a sliding lip portion 42;
It has a base part 43 that connects these inner peripheral parts 41 and the lip part 42 and is supported in contact with the flange part 27 via a seal protector 33. 41 and lip part 42
A recess 44 is formed between the two.

An auxiliary body 45 whose left end is supported by the spring receiver 13 is disposed in this recess 44, and this auxiliary body 45 is located in a part between it and the inner peripheral part 41 (on the left side in the figure).
A cylindrical part 46 has a conical shape that extends along the inner peripheral part 41 and has a slightly larger diameter on the right side while having a gap in the remaining part and is in light elastic contact with the other part. It has a large number of protrusions 47 as pressing parts extending in the radial direction, and these protrusions 47 urge the base part 43 toward the flange part 27 so as to press it with a predetermined preload. The end of the protrusion 47 extends to the extent of the connection between the lip portion 42 and the base portion 43, and is bent leftward from there to prevent damage. This protrusion 47 has a cylindrical portion 4 that comes into elastic contact with the inner peripheral portion 41.
6, the protrusion 47 is positioned relative to the base portion 43.

These protrusions 47 urge the base portion 43 toward the flange portion 27 side, but when the negative pressure generated in the subordinate pressure chamber 6 exceeds 100 to 150 mmHg, the force causes the base portion 43 to move forward and backward. The biasing force is such that the base portion 43 can be deformed toward the pressure chamber 6 by the applied pressure difference, so that hydraulic fluid can be replenished from the replenishment chamber 18 to the pressure chamber 6 side. However, base part 4
The lower half or inner circumferential portion of 3 is prevented from floating by an auxiliary body 45.

Therefore, in the embodiment shown in FIG. 3, the protrusion 47 is positioned with respect to the base part 43 by the cylindrical part 46, so that the sealing member 40 is not eccentric with respect to the base part. Part 43
is reliably pressed against the flange portion 27 by the protrusion 47 over the entire circumference. Therefore, no gap is created over the entire circumference of the low-pressure side of the base portion 43, and a part of the stroke of the piston 6 is not wasted to eliminate this gap, and play can be reduced.
Furthermore, since the base portion 43 is in a position where it contacts the flange portion 27 over the entire circumference, the lip portion 43
2 also does not unnecessarily deform to the left over the entire circumference, and there is no need to unnecessarily move the position of the loosening hole 21 to the left.
By reducing the distance between the master cylinder and the master cylinder, it is possible to shorten the master cylinder and reduce play.

As is clear from the above description, the present invention has the effect of reducing play in the master cylinder, but it is of course possible to implement the invention without being limited to the illustrated example.

That is, for example, instead of a conventional master cylinder, a portless type, inclined valve type, two-stage actuation type master cylinder, etc., or one using a lip type sealing member regardless of whether it is for a clutch or a brake. Even in the case of a tandem master cylinder, it can be applied to all or some of the many sealing members, and the sealing member or auxiliary body can be installed on the cylinder body side, and both can be fitted into the groove. You may also wear them.

The auxiliary body 45 may be made of metal or synthetic resin, but the former is preferable in terms of thermal effects and durability.

[Brief explanation of drawings]

1 and 2 are views showing a conventional example, FIG. 3 is a view showing an embodiment of the present invention, and FIG. 4 is a partially omitted front view of the auxiliary body shown in FIG. 3. 40... Seal member, 43... Base portion, 45
...Auxiliary body.

Claims (1)

[Scope of utility model registration request] A seal for the master cylinder that is attached to an annular recess formed in one side of the main body with a cylinder hole of the master cylinder or a piston movably fitted into the cylinder hole, and seals the liquid chamber formed in the cylinder hole. The apparatus includes: a base portion whose back surface is supported by the side surface of the annular recess; and a fitting portion that is integrally formed from one end of the base portion, fits into the bottom surface of the annular recess, and extends toward the liquid chamber. and a lip portion that is integrally formed from the other end side of the base portion, extends toward the liquid chamber, and comes into elastic contact with the other side of the cylinder hole or the piston, wherein the liquid chamber of the base portion an auxiliary member having an elastic pressing part extending in the radial direction along the side and pressing the base part toward the side surface of the annular recess; and a cylindrical part joining the fitting part and supporting the pressing part. A sealing device for a master cylinder consisting of a body.