JPH08113136A - Plunger type master cylinder - Google Patents

Abstract

PURPOSE: To provide a technorogy to prevent a damage of the sealing surface of a seal ring which is made in a trouble following the screwing in of a plug member. CONSTITUTION: A seal ring 158a positioning at the outer periphery side of a sleeve 136 close to a plug member 146, and contacting elastically to the inner wall of a cylinder hole, so as to cut off a non-pressure chamber 118 from a hydraulic pressure chamber 112 or an opening, is installed to a circular groove 148a provided on the outer periphery of the sleeve 136 to guide a piston in the cylinder hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder provided in a hydraulic brake system of a vehicle or the like and generating hydraulic pressure by a driver's operation. Above all, this invention
The present invention relates to a plunger type master cylinder.

[0002]

BACKGROUND OF THE INVENTION Generally, one of the master cylinders included in a hydraulic brake system of a vehicle is a plunger type master cylinder. The plunger type master cylinder is equipped with a cup seal on the cylinder body side for sealing the hydraulic chamber, and for communicating the non-pressure chamber and the hydraulic chamber on the piston side sliding in the cylinder body. Equipped with a loosening hole. Then, in response to the movement of the piston toward the hydraulic chamber in the cylinder hole, the loosening hole passes over the cup seal, and the hydraulic chamber is shut off from the non-pressure chamber. In such a plunger type, when shutting off the hydraulic chamber, the cup seal may be pushed into the opening of the loosening hole due to the hydraulic pressure difference between the hydraulic chamber and the non-pressure chamber, so-called seal erosion may occur. It has the advantage that it is small. However, on the other hand, in addition to this cup seal, other seal members necessary for such a master cylinder have problems such as a defective seal and damage. In the following, such a problem will be described after introducing the technique prior to the present invention together with the drawings.

FIG. 6 is a sectional view in the cylinder axis direction of a plunger type master cylinder 10 prior to the present invention (see, for example, Japanese Utility Model Laid-Open No. 4-125967). The master cylinder 10 is of a tandem type that generates hydraulic pressure in two independent systems. First on both ends
The primary piston 25 and the secondary piston 26 are inserted into the cylinder hole 13 having the second openings 15 and 16. These pistons 25 and 26 are slidably guided by first and second sleeves 35 and 36, respectively, and form first and second hydraulic pressure chambers 11 and 12, respectively. The respective sleeves 35 and 36 are first screwed to both openings 15 and 16 of the cylinder hole 13.
The inner end portions of the second plug members 45 and 46 are positioned in the cylinder hole 13.

On the outer peripheral side of the first sleeve 35 near the first plug member 45 screwed to the first opening 15 at one end,
The first seal ring 57 is located. The first seal ring 57 is mounted in a first annular groove 47 provided on the outer circumference of the first plug member 45, and elastically contacts the inner wall of the cylinder hole 13 to communicate with the hydraulic fluid reservoir. Is blocked from the first opening 15.

A second seal ring 58a is located on the outer peripheral side of the second sleeve 36 near the second plug member 46 screwed to the second opening 16 at the other end. further,
The sealing ring 58b is located on the second opening 16 side with respect to the second sealing ring 58a. Between the second seal ring 58a and the seal ring 58b, a discharge port (not shown) of the second hydraulic chamber 12 that opens in the inner wall of the cylinder hole 13 and an annular shape that extends in the inner wall of the cylinder hole 13 in the circumferential direction. The groove portion 14 is provided. The discharge port is the groove 1
It is in fluid communication with the second hydraulic chamber 12 via 4. The former second seal ring 58a shuts off the second non-pressure chamber 18 from the second hydraulic chamber 12. On the other hand, the latter sealing ring 5
Reference numeral 8b serves to shut off the second hydraulic chamber 12 from the outside of the cylinder hole 13. These rings 58a and 58b are mounted on the second annular groove 48a and the third annular groove 48b provided on the outer periphery of the second plug member 46, and are in elastic contact with the inner wall of the cylinder hole 13.

[0006]

The problems that occur because the seal members of the first seal ring 57, the second seal ring 58a, and the seal ring 58b are provided on the first and second plug members 45 and 46, respectively. was there. The first problem is that each plug member 4 when assembled
This is a problem of seal failure and damage to the seal member due to the screw connection of Nos. 5 and 46. That is, due to the screw connection, these seal members are moved to respective predetermined positions while rotating while being in elastic contact with the inner wall of the cylinder hole 13. Therefore, there is a possibility that each seal member is dragged in the rotation direction thereof and is mounted in the cylinder hole 13 in a twisted state.
If these seal members are mounted in a twisted state, it may not be possible to obtain perfect sealability. Further, the rotation while being dragged causes damage to the respective sealing surfaces, which is not preferable.

Especially, in the second seal ring 58a, the damage of the seal surface is remarkable. This is because, in addition to the long rotational movement amount of the second seal ring 58a, the second seal ring 58a passes through the opening of the discharge port of the hydraulic chamber 12 located on the inner wall of the cylinder hole 13 during the rotational movement, and therefore, during the passage thereof. This is because the edge portion of the opening is strongly contacted so as to enter the opening of the ejection port. Further, as shown in the drawing, when the annular groove portion 14 communicating with the discharge port is provided, the second seal ring 58a extends in the same circumferential direction as the rotation direction as compared with the edge portion of the opening of the discharge port itself. It will pass through a rather long edge portion of the groove 14. Therefore, the risk of damage to the seal surface due to contact with the edge portion increases.

The second problem is a problem in the manufacturing process of each plug member 45, 46. Each plug member 45, 46
Is made of metal to maintain strength during screw connection. With respect to the annular grooves 47, 48a, 48b provided in the respective metal plug members 45, 46, the respective seal members 57, 5
In order to improve the sealing performance of 8a and 58b, highly accurate finishing is required. The number of steps in the manufacturing stage increases by the amount of this finishing process. This leads to an increase in cost and is not preferable.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above points, and an object of the present invention is to provide a sealing surface for each seal member of the first seal ring 57, the second seal ring 58a and the seal ring 58b when they are assembled. The purpose is to provide technology to prevent damage. Still another object of the present invention is to provide a technique capable of omitting the finishing process for the annular grooves 47, 48a, 48b in which the respective seal members are mounted.

[0010]

As means for solving the above-mentioned problems, according to the present invention, the non-pressure chamber is located at the outer peripheral side of the sleeve near the plug member and elastically contacts the inner wall of the cylinder hole to form the liquidless chamber. A seal ring that shuts off the pressure chamber or opening is mounted in an annular groove on the outer circumference of the sleeve that guides the piston in the cylinder bore. By thus providing the sleeve with the seal ring, it is possible to prevent defective sealing and damage to the sealing surface due to screw connection of the plug member during assembly. That is, the assembling of the seal ring is performed by inserting the sleeve toward the inside of the cylinder hole along the cylinder axis. Therefore, since the seal ring is moved into the cylinder hole together with the sleeve without rotating, it is possible to prevent the seal ring itself from being twisted. Further, the seal ring does not move along the edge portion of the groove portion that extends in the circumferential direction on the inner wall of the cylinder hole, and the moving distance in a state of being in contact with the opening of the discharge port and the edge portion of the groove portion also becomes short. Therefore, it is possible to prevent damage to the sealing surface due to contact with the edge portion.

The sleeve provided with the seal ring is preferably made of synthetic resin rather than metallic material. In this way, when the synthetic resin is used for molding, the surface thereof is already in a sufficiently smooth state at the time of molding, and the finishing process for forming the sealing surface with respect to the annular groove for mounting the seal ring becomes unnecessary. Therefore, since the finishing process can be omitted, the manufacturing process can be simplified as compared with the case of using the metal sleeve.

The above can be applied not only to the single type plunger type master cylinder but also to another tandem type master cylinder. In other words, of course, it can be applied to a tandem type master cylinder in which both the primary system part and the secondary system part are plunger type, and one of the two systems is a plunger type and the other is a separate type. Model (for example, conventional type or center valve type)
It can also be applied to the above.

[0013]

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a cross-sectional view in the cylinder axis direction of a tandem type plunger master cylinder 100 that generates independent hydraulic pressure in two systems. (In FIG. 1, the members equivalent to the members in FIG. 6 are shown by adding 100 to the reference numerals given in FIG. 6.)

The outer shell is formed by the first openings 1 at both ends.
Cylinder hole 113 having 15 and second opening 116
It is the cylinder body 110 that forms the. Cylinder hole 11
In FIG. 3, a primary piston 125 is inserted near the first opening 115, and a secondary piston 126 is inserted near the second opening 116. Each such piston 1
25 and 126 are the first inserted into the cylinder hole 113.
The sleeve 135 and the second sleeve 136 are slidably fitted in the cylinder axial direction. Each sleeve 13
5, 136 are the first non-pressure chamber 117 and the second non-pressure chamber 1 which are connected to a hydraulic fluid reservoir (not shown) on the outer peripheral side thereof.
18 is formed. Each of these sleeves 135, 13
Reference numeral 6 denotes a first plug member 145 and a second plug member 146, which are molded of a synthetic resin (for example, Bakelite) and are screwed to the first and second openings 115 and 116.
It is positioned in the cylinder hole 113 by the inner end of the.
The first plug member 145 has a primary piston 125.
A through hole is formed so that the can can be received from the outside. On the other hand, the second plug member 146 is formed so as to cover the second opening 116.

The primary piston 125 and the secondary piston 126 define a first hydraulic chamber 111 in the cylinder hole 113. Further, the secondary piston 126 defines the second hydraulic chamber 112 in the cylinder hole 113 with the second plug member 146. In this way, a primary system portion is formed, which is mainly composed of the primary piston 125 and is operated by receiving an operation force from an external brake pedal. Further, a secondary system portion is formed mainly by the secondary piston 126, which is driven by the primary system portion.

The cylinder body 110 includes a first hydraulic chamber 111.
And a second discharge port (not shown) for discharging the hydraulic pressure of the second hydraulic chamber 112 to the outside. Particularly, between the second hydraulic chamber 112 and the second discharge port, an annular groove 114 formed on the inner circumference of the cylinder hole 113 and a communication passage extending in the radial direction at the inner end of the second plug member 146. 144 and the two are in fluid communication therethrough. A second seal ring 158a and a seal ring 158b are located on both sides of the groove 114 in the cylinder axis direction. Second seal ring 158
a and the sealing ring 158b both have cylinder holes 1
It makes elastic contact with the inner circumference of 13 to seal the second hydraulic chamber 112. A second seal ring 158 a located on the inner side of the cylinder hole 113 with respect to the groove 114 shuts off the second hydraulic chamber 112 from the second non-pressure chamber 118. On the other hand, the sealing ring 158b located on the second opening 116 side with respect to the groove 114
Shuts off the second hydraulic chamber 112 from the second opening 116.

As described above, the second seal ring 158a positioned on the inner side of the groove 114 is more damaged on the sealing surface than other seal members.
Therefore, here, a structure capable of particularly preventing damage to the seal surface of the second seal ring 158a is shown.

The second seal ring 158a is mounted in the second annular groove 148a provided on the outer circumference of the second sleeve 136. By mounting on the second sleeve 136 in this way, the assembly can be performed by inserting the cylinder sleeve in a fixed direction. Therefore, it is possible to prevent defective sealing and damage to the sealing surface due to the conventional rotational movement. Further, since the second seal ring 158a at the time of assembly passes over the second discharge port and the groove portion 114 along the cylinder axial direction, sealing by contact with the edge portion of the second discharge port and the groove portion 114 is performed. Surface damage can also be prevented. Therefore,
It is possible to reliably prevent the damage to the sealing surface, which has been remarkable until now. Further, the second sleeve 136 to which the second seal ring 158a is attached is made of synthetic resin, so that the step of highly accurate finishing process for the second annular groove 148b which has been necessary until now can be omitted.

Groove portion 11 with respect to second seal ring 158a
Sealing ring 1 located on the side of the second opening 116 across 4
58b is mounted in a third annular groove 148b provided on the outer circumference of the second plug member 146. The sealing ring 158b is the second
In order to avoid damage to the sealing surface when the plug member 146 is screwed together, the plug member 146 can be provided at a position 158f that is sandwiched between the second opening 116 and the flange portion of the second plug member 146. However, at this position 158f,
The shavings generated during screw connection may enter the second hydraulic chamber 112. Therefore, in consideration of the removal of the shavings, although there is a slight rotational movement, the moving distance is relatively short, and the groove 114 is not passed. Sealing ring 1
58b is mounted in the annular groove 148b of the second plug member 146.

As a seal member for sealing the second hydraulic pressure chamber 112, in addition to these rings 158a and 158b, a second hydraulic pressure chamber 112 is located on the second hydraulic pressure chamber 112 side with respect to the second sleeve 136.
There is a cup seal 186. Second cup seal 186
Is a loosening hole 17 formed in the secondary piston 126.
Due to the change in the relative positional relationship with the second hydraulic chamber 11,
The second and the second pressureless chambers 118 are communicated / interrupted.

The second cup seal 186 has a pair of lip portions 186a, 186c extending toward the second hydraulic chamber 112 on the inner and outer circumferences thereof, and a pair of these lip portions 186.
a, 186c, and the second hydraulic chamber 112, and a base portion 186b connecting the remote end portions. Second cup seal 18
6 is mounted in an annular recess 136d formed on the inner circumference of the second sleeve 136. That is, of the pair of lip portions, the inner lip 186 a located on the inner peripheral side thereof elastically contacts the outer periphery of the secondary piston 126, and the outer lip 186 c located on the outer peripheral surface thereof elastically contacts the inner periphery of the second sleeve 136. In the prior art up to now (see FIG. 6), the second
The outer lip 86c of the cup seal 86 was in elastic contact with the inner circumference of the second plug member 46. On the other hand, here, the outer lip 186c is provided so as to elastically contact the second sleeve 136 made of synthetic resin whose surface is already smooth at the time of molding. Therefore, it is possible to omit the highly accurate finishing process for the second plug member 146, which has been necessary to obtain a good sealing property.

FIG. 4 is a partially enlarged view of the second cup seal 186 and its periphery. This second cup seal 18
The second sleeve 136 made of synthetic resin that supports 6 is formed with a communication hole 136e that allows the opposite side of each lip of the base portion 186b to communicate with the second pressureless chamber 118 at all times. For example, when the second hydraulic chamber 112 is in a negative pressure state, such as when the secondary piston 126 returns to the non-operating position on the first opening 115 side after the hydraulic pressure is generated in the second hydraulic chamber 112, the secondary In order to promote the returning movement of the piston 126, it is necessary to supply the hydraulic fluid from the second non-pressure chamber 118 to the second hydraulic chamber 112. The communication hole 136e has a function of supplying the working fluid. In other words, due to the pressure difference between the second hydraulic chamber 112 in the negative pressure state and the second non-pressure chamber 118 kept at the atmospheric pressure, the hydraulic fluid on the second non-pressure chamber 118 side passes through the communication hole 136e and becomes 2 cup seal 186
The second hydraulic chamber 1 while inclining the outer peripheral lip 186c of the inner side.
I'm trying to run into 12. In addition, in order to prevent the second cup seal 186 from biting into the opening portion of the communication hole 136e, an annular thin disc cup spacer 136s is arranged between the two.

By the way, in the second plug member 146 for supporting the second sleeve 136 from the second opening 116 side, a communication groove 146h extending in the radial direction of the cylinder shaft is formed at the inner end portion thereof.
Are formed. The communication groove 146h is provided in the second sleeve 1
The second hydraulic chamber 112 and the groove 114 together with the end face of 36.
And a communication passage 144 communicating with and. FIG. 5 is an enlarged configuration diagram of the second plug member 146 including the communication groove 146h. In the prior art up to now (see FIG. 6), the communication between the second hydraulic chamber 12 and the groove portion 14 utilizes a hole located on the inner end side of the second plug member 46 and extending in the radial direction of the cylinder shaft. It was In this case, after the second plug member 46 was formed in the forging step, mechanization for forming the hole was required. On the other hand, here, instead of the hole, the connecting groove 146h is used. The outer end of the second plug member 146 is formed with a two-sided width 146k for rotating itself by using a tool at the time of screw connection, but the connecting groove 146h is formed when the second plug member 146 is formed. , And can be formed at the same time by utilizing the forging process when forming the width across flats 146k. Therefore, it is possible to omit the machining process which has been necessary until now, and it is possible to simplify the manufacturing process. This connecting groove 146h may be the second groove in the second sleeve 136.
You may provide in the edge part by the side of the plug member 146. Even in this case, the manufacturing process can be simplified.

[0024]

[Second Embodiment] FIG. 2 is a sectional view of a tandem type plunger type master cylinder 200 according to a second embodiment of the present invention. (In FIG. 2, members equivalent to the members in FIG. 6 described above are denoted by the reference numeral 200 in FIG.
It is shown using a sum of. Although the structure is almost the same as that shown in the first embodiment, the master cylinder 200 also has a feature on the primary system side. That is, the first annular groove 247 is provided on the outer circumference of the first sleeve 235 that guides the primary piston 225, and the first seal ring 257 is provided in the first annular groove 247.
I am wearing. The first seal ring 257 makes elastic contact with the inner wall of the cylinder hole 213, and shuts off the first pressureless chamber 217 from the first opening 215. According to such a configuration, the first seal ring 257 will not be assembled while rotating as before. That is, the first sleeve 2
Together with the assembly of No. 35, it is assembled in a fixed direction along the cylinder axis. Therefore, it is possible to prevent defective sealing and damage to the sealing surface due to the rotational movement.

Further, pay attention to the first sealing member 251 located on the first plug member 245 side of the first sleeve 235. The first sealing member 251 is mounted in an annular recess provided in the inner circumference of the first sleeve 235 on the first plug member 245 side. The first sealing member 251 makes elastic contact with the outer circumference of the primary piston 125 and the inner circumference of the first sleeve 235, and isolates the first pressureless chamber 217 from the outside of the cylinder hole 213. In the prior art up to now (see FIG. 6), such a first sealing member 51 has a metal first plug member 45.
It was in contact with the inner circumference of. However, if it is elastically contacted with the first sleeve 235 made of synthetic resin as in the second embodiment, the first sealing member 25 can be provided in the same manner as described above.
It is possible to omit a highly accurate finishing process for forming the first sealing surface.

[0026]

[Third Embodiment] FIG. 3 is a sectional view of a tandem type plunger type master cylinder 300 according to a third embodiment of the present invention. (In FIG. 3, members equivalent to the members in FIG. 6 described above are denoted by the reference numeral 300 in FIG.
It is shown using a sum of. ) This master cylinder 300 is characterized by the side of the secondary system portion. The second sleeve 336 is provided with the second hydraulic chamber 311 on the second hydraulic chamber 311 side.
A cup-shaped second sealing member 352 is located on the inner peripheral side of the sleeve 336, and an O-ring 354 having a circular cross section is located on the outer peripheral side thereof. The second sealing member 352 is
The second piston 336 is mounted in an annular recess formed in the inner circumference of the end of the second sleeve 336 on the first hydraulic chamber 311 side.
6 and the inner circumference of the second sleeve 336. On the other hand, the O-ring 354 is mounted in an annular groove formed on the outer circumference of the second sleeve 336 and elastically contacts the inner circumference of the cylinder hole 313. These second sealing members 352 and O-
The first hydraulic chamber 311 is isolated from the second non-pressure chamber 318 by the ring 354.

The first hydraulic chamber 311 and the second non-pressure chamber 318
In the prior art up to now (see FIG. 6),
The single cup seal 52 elastically contacts the inner circumference of the cylinder hole 13 and the outer circumference of the secondary piston 26. However, as in the third embodiment, the second sealing member 352 and the O-ring 354 make up the O-ring 3 although the number of parts is increased as compared with the prior art.
The surface roughness of the portion of 54 that is in elastic contact with the inner circumference of the cylinder hole 313 may be rough. Therefore, the highly accurate finish machining of the inner circumference of the cylinder hole 313 is not required as much as when the single cup seal 52 is elastically contacted until now, and the cylinder hole 31 is correspondingly required.
The processing step 3 can be simplified. In the third embodiment, in order to limit the movement stroke of the secondary piston 326 toward the primary system portion side, a stopper bolt 319 screwed from the outside of the cylinder is provided.

As described above, the tandem type is shown as the embodiment of the present invention. However, the present invention is not limited to such a tandem type, but it is a plunger type master cylinder, which is screwed to the opening of the end of the cylinder hole and is closer to the plug member that positions the sleeve in the cylinder hole, and the inner wall of the cylinder hole. It can be widely applied as long as it is provided with a seal ring which elastically contacts with and which shuts off between the liquid chamber via the outer peripheral side of the sleeve or between the liquid chamber and the outside of the hole.

[0029]

As described above, in the present invention, the non-pressure chamber is elastically contacted with the inner wall of the cylinder hole at a position close to the plug member screwed to the opening of the cylinder hole, and the non-pressure chamber is opened from the hydraulic chamber or the opening. By mounting the seal ring for blocking in the annular groove formed on the outer circumference of the sleeve positioned by the plug member, the seal ring is prevented from rotating and twisting due to the screw connection of the plug member, thereby preventing a seal failure and a seal. It is possible to prevent damage to the ring itself.
According to the present invention, the seal ring has a discharge port that opens on the inner wall of the cylinder hole, or the discharge port-
In those located on the cylinder hole inner side than the annular groove that connects between the hydraulic chambers, it is possible to avoid strong contact with the opening of the discharge port or the edge of the groove while the seal ring rotates. Damage to the seal ring due to rotational contact with its edge can also be effectively prevented. Further, in the present invention, by forming an annular groove for mounting the seal ring on the sleeve made of synthetic resin, mechanical finishing of the plug member and the sleeve for forming the sealing surface for the seal ring becomes unnecessary. Thus, the manufacturing process can be simplified.

[Brief description of drawings]

FIG. 1 is a sectional view of a plunger type master cylinder 100 according to a first embodiment.

FIG. 2 is a sectional view of a plunger type master cylinder 200 according to a second embodiment.

FIG. 3 is a sectional view of a plunger type master cylinder 300 according to a third embodiment.

FIG. 4 is an enlarged view of a portion around a second cup seal 186 mounting portion in FIG.

5 is an enlarged configuration diagram of a first plug member 145 shown in FIG.

FIG. 6 is a prior art plunger type master cylinder 1
0 cross section

[Explanation of symbols]

10, 100, 200, 300 Plunger type master cylinder 10, 110, 210, 310 Cylinder body 11, 111, 211, 311 First hydraulic chamber 12, 112, 212, 312 Second hydraulic chamber 14, 114 Groove portion 17, 117,217 1st non-pressure chamber 18,118,318 2nd non-pressure chamber 25,125,225,325 Primary piston 26,126,226,326 Secondary piston 35,235 1st sleeve 36,136,336 2nd sleeve 45,245 first plug member 46,146 second plug member 47,147,247 first annular groove 48a, 148a second annular groove 48b, 148b third annular groove 57,157,257 first seal ring 58a, 158a 2 seal ring 58b, 158b seal ring 186 2nd cup Le

Claims (10)

[Claims] 1. A cylinder body having a cylinder hole having an opening at at least one end, a sleeve which is inserted into the cylinder hole and which forms an unpressurized chamber communicating with a hydraulic fluid reservoir on the outer peripheral side, and a sleeve of the sleeve. A piston that slidably fits on the inner periphery to partition the hydraulic chamber in the cylinder hole; and a plug member that is screwed to the opening and that positions the sleeve in the cylinder hole by the inner end. A pair of sealing members, which are respectively disposed on the stepped portions formed by the respective end portions of the sleeve and through which the piston slidably penetrates, and an inner wall of the cylinder hole, which is located on the outer peripheral side of the sleeve near the plug member. A seal ring that elastically contacts to isolate the non-pressure chamber from the hydraulic chamber or the opening, and one of the pair of sealing members is provided to move the piston toward the hydraulic chamber. Accordingly, in the plunger type master cylinder that is a cup seal that blocks the fluid communication between the hydraulic chamber and the non-pressure chamber via the loosening hole provided in the piston, the seal ring is formed on the outer circumference of the sleeve. Plunger type master cylinder that is mounted in the annular groove. 2. A primary system part that operates by receiving an operating force from a brake pedal by inserting two pistons into a cylinder hole formed in a cylinder body, and a secondary system that follows this primary system part. A sleeve that forms a non-pressure chamber that is inserted into the cylinder hole and is connected to the hydraulic fluid reservoir on the outer peripheral side, and an internal end that is screwed to the opening of the cylinder hole. A plug member that positions the sleeve in the cylinder hole, a piston that slidably fits the inner circumference of the sleeve to partition a hydraulic chamber between the plug member, and each end of the sleeve. And a pair of sealing members, which are respectively disposed on the stepped portions formed by the piston and slidably penetrate the piston, and are located on the outer peripheral side of the sleeve near the plug member. A seal ring that elastically contacts the inner wall of the cylinder hole to shut off the non-pressure chamber from the liquid pressure chamber, and the liquid pressure chamber is provided between the plug member and the inner wall of the cylinder hole. And a discharge port that opens to the inner wall of the cylinder hole between the seal ring and the seal ring and communicates with the hydraulic chamber, and one of the pair of seal members is In a plunger type master cylinder that is a cup seal that blocks fluid communication between the hydraulic chamber and the non-pressure chamber via a loosening hole provided in the piston in response to movement of the piston toward the hydraulic chamber. The plunger type master cylinder, wherein the seal ring is mounted in an annular groove formed on the outer circumference of the sleeve. 3. The plug member is made of metal, and
The sleeve according to claim 1 or 2, wherein the sleeve is made of synthetic resin.
Plunger type master cylinder. 4. The plunger type master cylinder according to claim 1, wherein at least the cup seal of the pair of sealing members is mounted in an annular recess formed on the inner peripheral side of the end portion of the sleeve. 5. The cup seal has a pair of lip portions extending from the base portion on the inner and outer peripheries, and the tip end side of the pair of lip portions is directed toward the hydraulic chamber side, and the inner peripheral side of the end portion of the sleeve. The plunger according to claims 1 to 3, wherein the sleeve is mounted in an annular recess formed in, and the sleeve is formed with a communication hole for always communicating the side of the base section opposite to the lip section with the pressureless chamber. Type master cylinder. 6. The inner wall of the plug member and the cylinder hole, wherein the hydraulic chamber is formed between the piston and the plug member, and a sealing ring for blocking the hydraulic chamber from the outside of the cylinder hole is provided. The plunger type master cylinder according to claim 1 or 3-5, which is provided between the master cylinder and the plunger. 7. The sealing ring is mounted in an annular groove formed on the outer circumference of the plug member.
Plunger type master cylinder. 8. A notch extending in the radial direction of the cylinder hole is formed on an inner end surface of the plug member or at least one end surface of an end surface of the sleeve engaging with the plug member, and the hydraulic chamber includes: The plunger type master cylinder according to any one of claims 2, 6 and 7, wherein the plunger type master cylinder is connected via a notch to a discharge port that is opened on the inner wall of the cylinder hole between the seal ring and the sealing ring. 9. An annular groove portion, which is located between the seal ring and the sealing ring and extends in the circumferential direction of the cylinder hole to connect the hydraulic chamber and the discharge port, on the inner wall of the cylinder hole. Is formed, claim 2 or 6 to
8 plunger type master cylinder. 10. The plug member has an inner end portion that engages with an end portion of the sleeve opposite to the hydraulic chamber side, and the piston can receive an operating force from the outside of the cylinder hole. Through hole is formed to fit
The plunger type master cylinder according to claim 1, or 3 to 5.