JP2003261020A - Plunger type master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the liquid supply property (the supply property of a working fluid from a reservoir 30 side to a liquid pressure chamber 1020) while performing the durability of a seal ring. <P>SOLUTION: A system to supply the working fluid through an aperture passage P is newly provided in addition to a system to supply the working fluid by collapsing an outer circumferential lip part 750, or a system to supply the working fluid through a through-hole 2302 penetrating a guide member 520. The aperture passage P is obtained by an end face projecting part 770 of a base part 700 of the seal ring 70. The new supply system through the aperture passage P can supply the liquid any time because it is constantly open compared with the system to, supply the liquid by collapsing the outer circumferential lip part 750, and also supply the liquid effectively because the flow resistance is relatively small. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger type master cylinder used in a hydraulic brake system of a vehicle, and more particularly to a brake control (for example, a vehicle attitude control) which is performed separately from a manual brake control by a driver. Of the master cylinder suitable for automatic brake control for vehicle or traction control for controlling the braking force of driving wheels during vehicle acceleration).

[0002]

BACKGROUND OF THE INVENTION This type of plunger type master cylinder has a relief port on the side of the moving piston and a seal ring for opening and closing the relief port on the side of the cylinder housing, contrary to the conventional type master cylinder. The piston defines a hydraulic chamber inside the cylinder hole of the cylinder housing, and the relief port of the piston communicates with the hydraulic fluid supply passage of the cylinder housing (that is, the communication passage communicating with the reservoir). . When the brake is not actuated without normal human brake control, the relief port is in communication with the reservoir through the open communication passage, and thus the hydraulic chamber is in the non-pressure state. On the other hand, when the brake is operated, the piston moves to the hydraulic pressure chamber side by the brake operation, the relief port of the piston is blocked by the seal ring on the cylinder housing side, and the master cylinder generates brake hydraulic pressure in the hydraulic pressure chamber. Compared to the conventional type, this type of master cylinder has less seal erosion (the phenomenon that the lip of the seal ring bites into the opening of the relief port) and the durability of the seal ring is higher. Be seen.

However, when the plunger type master cylinder is applied to automatic brake control or traction control which is performed separately from the driver's manual brake control, hydraulic fluid is supplied from the reservoir side to the hydraulic chamber. (Hereinafter, this is referred to as liquid replenishment or liquid replenishment property). In order to reduce the invalid stroke due to human brake operation,
The hole of the relief port on the piston side is very small, for example, about 2 mm, and when the brake is not operating, the end face of the base portion of the cup-type seal ring on the cylinder housing side faces the opening of the relief port on the piston side. The layout is such that it partially blocks the opening of the port. Therefore, the liquid passage area at the opening of the relief port, which originally has a small hole diameter, is substantially very small,
Poor liquid replenishment through the relief port. This liquid replenishment property is important for quick and smooth automatic brake control and traction control. This is because in automatic brake control, traction control, etc., the liquid supply through the relief port is used, and the brake fluid pressure is supplied to the brake operating device outside the master cylinder through the relief port and the hydraulic chamber.

[0004]

Therefore, it is required to increase the amount of hydraulic fluid on the reservoir side to the hydraulic chamber by expanding the passage area of the opening portion of the relief port. In this regard, until now, measures have been taken exclusively to improve the liquid replenishment property by increasing the clearance between the piston and the member that fits on the outer periphery of the piston (for example, the drawing in Japanese Patent Laid-Open No. 2000-71969). Two
reference). However, if the clearance of the outer peripheral portion of the piston becomes large, there is a risk that the inner peripheral side of the base portion of the cup-type seal ring will be eaten by the clearance portion.

On the other hand, in this type of master cylinder, in addition to the liquid replenishment through the relief port, the outer peripheral lip portion of the cup type seal ring is tilted (that is, opened).
The hydraulic fluid can be replenished from the outer circumference of the piston to the hydraulic chamber without passing through the relief port. Therefore, it is possible to adopt the idea of increasing the efficiency of liquid replenishment from such a peripheral lip portion. However, the latter method has a drawback that the liquid cannot be supplied unless the outer peripheral lip portion is opened. For example, even if an electric pump for automatic brake control is activated, unless the operating pressure (suction force to the hydraulic chamber side) reaches the valve opening pressure of the outer peripheral lip portion, the outer peripheral lip portion is sealed. The liquid will not be able to be replenished from the outer peripheral lip portion.

Therefore, an object of the present invention is to provide a plunger type master cylinder capable of effectively improving the liquid replenishment property while improving the durability of the seal ring. Another object of the present invention is to provide a plunger type master cylinder having a new liquid replenishing function that can coexist well with the liquid replenishment from the outer peripheral lip portion. Another object of the present invention is to provide a plunger type master cylinder capable of enhancing the liquid replenishment property to the hydraulic chamber without unnecessarily increasing the number of parts. Other objects of the present invention will be apparent from the following description.

[0007]

According to the present invention, a gap passage which is always open is provided between the end face of the base portion of the cup-shaped seal ring and the member on the cylinder housing side adjacent to the end face. Since the end surface of the base portion of the seal ring faces the relief port on the piston side, the clearance passage faces the relief port. Since the clearance passage is always open and faces the relief port, the working fluid can be smoothly supplied at any time when liquid replenishment is required. Here, "the end surface of the base portion of the seal ring faces the relief port on the piston side" means
This means a state in which the end face of the base portion faces the relief port in the axial direction of the cylinder hole (or piston). Preferably, the base portion partially closes the opening of the relief port and opens the remaining portion of the opening.
Because of the arrangement of the end faces of the base portion, the clearance passage defined by the end faces directly opens to the relief port, so that the flow resistance at that portion is small.

In this way, the relief port is attached to the end face of the base portion.
The idea of providing a normally open passage facing the room is a completely new idea of liquid replenishment. This new idea is
It matches well with the concept of replenishing the hydraulic fluid by tilting the outer lip of the seal ring. Because,
This is because the route from the bar side to the outer peripheral lip portion is common with the route to the clearance passage. Further, the new supply passage of the present invention coexists with another passage from the through hole of the guide member for guiding the piston to the relief port,
Liquid replenishment can be effectively performed as a whole. further,
In the present invention, since it is not necessary to increase the clearance between the piston and the member that fits in the piston, there is little risk of so-called seal erosion, and it is preferable from the viewpoint of the durability of the seal ring.

It is preferable to form a clearance passage in the end face of the base portion of the seal ring without increasing the number of parts and performing the extra processing as much as possible. From such a viewpoint, the form of the clearance passage is as follows. First
In addition, a clearance passage (that is, a clearance passage due to the protrusion) formed by integrally providing a protrusion on at least one of the end surface of the base portion of the seal ring and the member on the cylinder housing side adjacent thereto. Secondly, a clearance passage (that is, a clearance passage formed by a recess or a groove) by providing a recess on at least one of the end surface of the base portion of the seal ring and the member on the cylinder housing side adjacent thereto. Thirdly, a clearance passage (a clearance passage due to a combination of a projection and a recess is provided by combining a projection and a recess on an end surface of the base portion of the seal ring and / or a member adjacent to the cylinder housing side. ).

A plurality of protrusions are provided in the circumferential direction, for example, ten, and a plurality of recesses are provided in the circumferential direction, each of which is provided with a plurality of radially extending radially, for example, six. . The height or depth of the protrusions and recesses is at least smaller than the hole of the relief port, and preferably about half or less than the size of the open portion of the relief port. Is good. Further, by providing a recess in addition to the protrusion, it is possible to secure the required flow passage area while further reducing the distance between the end surface of the base portion and the adjacent member on the cylinder housing side. it can. In that case, it is also possible to provide one of the protrusions or recesses on either the end face of the base portion or the member adjacent to the cylinder housing side, and the other of the protrusions or recesses on the remaining side. Considering the alignment of the protrusion and the recess and further processing, both the protrusion and the recess (for example, the recess is placed between the protrusions are formed on the base portion of the seal ring that can be integrally processed by molding. It is better to provide (). From the processed surface, the same applies when providing either the protrusion or the recess,
It is preferable to utilize the molding process of the seal ring.

Further, in order to keep the cup-shaped seal ring in a stable state, it is preferable that the free end of the inner peripheral lip portion is brought into contact with the side of the cylinder housing so that the seal can be moved even when the piston moves. -It is advisable to prevent the ruling from moving axially. The form is also effective in preventing the variation or increase in the invalid stroke.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a tandem type plunger type master cylinder to which the present invention is applied. The tandem type master cylinder 10 includes a primary portion 101 and a secondary portion 102 that are independent of each other. In the embodiment shown in the figure, the idea according to the invention is applied to both parts 101 and 102, but both parts 101 and 10
Since the same applies to the second example, the secondary part 102 will be mainly described here. Of course, the present invention can be applied to only one of the two parts 101 and 102 by making one of the parts 101 and 102 a plunger type and the other one of the other types, for example, a center valve type. You can also

First, with reference to FIG. 1, the overall structure of a tandem type master cylinder 10 will be clarified.
Note that the entire configuration itself is the same as a known configuration except for a part thereof. Therefore, the description of similar parts is simplified or omitted.

The outer contour of the master cylinder 10 is a cylinder housing body 22 made of an aluminum alloy. The cylinder housing main body 22 has a boss portion 22s for supporting the reservoir 30 at an upper portion, and an internal hole 220 having a diameter gradually increasing from one closed end inside thereof. The small-diameter hole portion 2201 at the inner side of the inner hole 220 has a resin sleeve 40, and
The metal cylindrical piston guide 50 extends from the small-diameter hole portion 2201 to the medium-diameter hole portion 2202 and further near the large-diameter opening of the internal hole 220. Regarding the piston guide 50, in consideration of assembling a sealing ring or assembling itself into the internal hole 220,
The entire body is divided into three parts, which are composed of a piston guide main body 500, and secondary side guide members 520 and primary side guide members 510 located at both ends of the piston guide main body 500. The guide member 520 on the secondary side is integrated with the piston guide body 500 by the positioning pin 530, whereas the guide member 510 on the primary side is the piston guide body 5.
Separated from 00.

A metallic cylindrical cap member 60 is screwed to the large-diameter opening of the inner hole 220. The cylinder housing main body 22, the sleeve 40, the piston guide 50, and the cap member 60 cooperate with each other to form the cylinder housing 20, and define a cylinder hole 200 in which one end is closed and the other end is opened and extends in the axial direction. Further, the cylinder housing 20 has the boss portion 2
A communication passage 23 for connecting the inside of the reservoir 30 and the hydraulic chamber inside the cylinder hole 200 through the inner circumference of 2s.
I have 0. The communication passage 230 includes the primary portion 1
Both 01 and the secondary part 102 are in the components of the cylinder housing 20. For example, looking at the secondary portion 102, from the bottom of the boss portion 22s of the cylinder housing main body 22 to the cylinder housing main body 2
The outer passage portion 2301 penetrating the second wall and the hole passing through the guide member 520.
The inner passage portion 2302 communicating with 01 is the communication passage 2
Make up thirty.

Further, the cylinder housing 20 defining the cylinder hole 200 supports a seal ring composed of a cup-shaped seal in both the primary portion 101 and the secondary portion 102. That is, the sleeve 40 and the guide member 520 on the secondary side support the seal ring 70 of the secondary portion 102 between the ends facing each other, and are separated from each other.
0 and the guide member 510 on the primary side support the seal ring 70 of the primary portion 101 between the portions facing each other. In this embodiment, by partially changing the seal ring 70 as described above,
Establish a new gap passage for liquid replenishment. That point,
More on this later.

On the other hand, inside the cylinder hole 200, the secondary return spring 8 is provided from the back toward the opening.
2, secondary piston 92, caged spring 8
1 and the primary piston 91 are sequentially inserted. As a result, the secondary piston 92 cooperates with the seal ring 70 of the secondary portion 102, the second hydraulic chamber 1020 is provided deep inside the cylinder hole 200, and the primary piston 91 is connected to the seal ring 70 of the primary portion 101. Together, the first hydraulic chamber 1010 is partitioned between the primary piston 91 and the secondary piston 92.

Further, the secondary piston 92 and the primary piston 91 have a cylindrical portion 92 having an internal space.
It contains 0,910. Each of the cylindrical portions 920 and 910 has a plurality of relief ports 900 penetrating the wall of the cylinder. The cross-sectional shape of each relief port 900 is a circle, and the diameter thereof is, for example, 2 mm. The number of relief ports 900 is, for example, four for each piston 92, 91. The four relief ports 900 are located equidistantly from each other along the circumference of the piston 92, 91 that is orthogonal to the axis. Each relief port 900 is
In the non-operating state of the normal brake shown in FIG. 1, the second and first hydraulic pressure chambers 1020 and 1010 and the reservoir 3
It communicates with each of the communication passages 230 communicating with the 0 side. When the driver performs a brake operation with the brake pedal from such a state, the pistons 91 and 92 move toward the inside of the cylinder hole 200, and the seal rings 70 on the cylinder housing 20 side cause the hydraulic chambers 1010 to move. , 1
Brake fluid pressure is generated at 020. Such normal human braking is basically the same as before. In addition, the master cylinder 10 according to the present invention has a specific clearance passage (described later) on the end surface of the base portion of each seal ring 70, so that liquid replenishment during pumping break can be effectively performed. it can.

Next, referring to FIGS. 2 and 3, the secondary piston 92 (or the primary piston 9)
Pay attention to the seal ring 70 that slides on the outer peripheral surface of 1). The seal ring 70 is of a cup type, for example, 1
A base portion 700 having a thickness of about mm, an inner peripheral lip portion 730 that abuts the secondary piston 92 (or the primary piston 91), and an outer peripheral lip portion 750 that abuts the inner periphery of the cylinder hole 200 are provided. The cup-type seal ring 70 is a molded product of ethylene-propylene rubber, and the outer peripheral lip portion 750 and the inner peripheral lip portion 730 are
It is integrated with the base part 700. The seal ring 70 has the base portion 700 with the inner and outer peripheral lip portions 730 and 750 directed toward the hydraulic chamber 1020 (or the hydraulic chamber 1010).
Are arranged so as to partially cover the opening of the relief port 900. The opening portion of the released relief port 900 is
Although it corresponds to the ineffective stroke of the master cylinder 10, in order to secure the liquid replenishment through the relief port 900, the release port 900 of the base portion 700 is opened to a size larger than the block size. It is preferable to make the size larger.

FIG. 4 clarifies the shape and structure of the cup-shaped seal ring 70. The ring-shaped seal ring 70 is integrally provided with ten protrusions 770 on the end surface of the base portion 700 in a scattered manner along the circumferential direction.
The protrusions 770 are adjacent to each other and are spaced apart from each other at equal intervals, and each protrusion 770 is shaped like a part of a sphere having a height of about 0.4 mm and a size of 4 to 5 mm. The seal ring 70 is
The tops of the protrusions 770 are applied to the adjacent members (each guide member 520, 510), whereby the base portion 700 is formed.
And an end surface of the guide member 520 (510) forms a clearance passage P. The clearance passage P is a passage that communicates with the inside and outside in the radial direction of the seal ring 70 and is always open. The inside of the clearance passage P in the radial direction is a relief port 90.
It is located on the opening 0, and the outer side in the radial direction communicates with the passage C provided on the outer periphery of the guide member 520 (510). The passage C is a clearance on the outer circumference of the guide member 520 (510). Therefore, the passage C not only serves as a relay point for a replenishment system that passes through the clearance passage P and the relief port 900, but also serves as a relay point for another replenishment system that tilts the outer peripheral lip portion 750 to replenish. . The clearance on the inner peripheral side of the guide member 520 (510) is smaller than the clearance of the passage C, so that the original piston guide function of the guide member 520 (510) can be smoothly performed.

The master cylinder 10 is normally operated in a non-brake state from the reservoir 30 side to the hydraulic chamber 1020.
As a system for replenishing the working fluid with respect to (1010), in addition to a system for reclining the outer peripheral lip portion 750 to replenish the working fluid, or a system for replenishing the working fluid through a through hole 2302 penetrating the guide member 520 (510), , A system for replenishing the working fluid through the clearance passage P is newly provided. Clearance passage P
The new replenishment system that passes through is always open, so it is possible to replenish the liquid at any time as compared with the system that tilts the outer peripheral lip portion 750 to replenish the liquid, and also because the flow resistance is relatively small. The liquid can be effectively replenished. Therefore, when performing a brake control (for example, an automatic brake control for controlling the attitude of the vehicle or a traction control for controlling the braking force of the driving wheels at the time of vehicle acceleration) other than the normal human braking operation, the relief control is performed. Through the port 900, liquid can be effectively replenished to the brake operating device outside the master cylinder. By applying the tip of the inner peripheral lip portion 730 of the seal ring 70 to an adjacent member (for example, the sleeve 40), the seal ring 70 is not displaced in the axial direction due to the reciprocating movement of the piston. Can be

Further, in the embodiment shown in FIGS. 1 to 4, in order to obtain the clearance passage P, the base portion 700 of the seal ring 70 is formed.
Although the protrusion 770 is provided on the end surface of the, the recess may be provided instead of the protrusion. As the recess, for example, FIG.
It is possible to apply six grooves 780 arranged at equal intervals as shown in FIG. The groove 780 as a recess is shown in FIG.
As shown in FIG. 5, the guide member 520 adjacent to the end surface of the base portion 700 can be processed. When the clearance passage is obtained by the concave portion, the end face of the base portion 700 can be brought into contact with the end faces of the adjacent guide members 520, so that the ineffective stroke can be made smaller than when the protrusion portion is used.

Further, the guide member 510 on the primary side is provided.
With respect to, the cap member 60 may be integrally formed with the inner circumference. 7 and 8 are specific examples thereof,
The cap member 60 ′ has a portion 51 corresponding to a guide member.
It is provided with 0'and a portion 230 'constituting a communication passage.

[Brief description of drawings]

FIG. 1 is a cross-sectional view taken along the axis of a tandem type plunger master cylinder that is an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion surrounded by a circle 2 in FIG.

FIG. 3 is an enlarged sectional view of a portion surrounded by a circle 3 in FIG.

FIG. 4 shows an example of a seal ring used in the present invention, (4a) is a front view, and (4b) is a sectional view taken along the line A-A of 4a.

FIG. 5 shows another example of the seal ring used in the present invention, (5a) is a front view, and (5b) is a sectional view taken along the line EE of 5a.

FIG. 6 is a front view of a guide member including a recess (groove).

FIG. 7 is a partial cross-sectional view showing a modification of the primary side.

8 is an enlarged cross-sectional view of a portion surrounded by a circle 8 in FIG.

[Explanation of symbols]

10 Tandem type plunger master cylinder 101 Primary part 102 secondary part 1010 First hydraulic chamber 1020 Second hydraulic chamber 20 cylinder housing 22 Cylinder housing body 200 cylinder holes 230 communication passage 50 Piston guide 500 piston guide body 510, 520 guide member 70 seal ring 700 base 730 Inner peripheral lip 750 outer peripheral lip 770 protrusion 780 groove (recess) 91 Primary piston 92 Secondary piston 900 relief port

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhisa Hira             5293 Urago-cho, Yokosuka City, Kanagawa Prefecture             Bosch Brake System Co., Ltd. (72) Inventor Tetsuya Masuda             5293 Urago-cho, Yokosuka City, Kanagawa Prefecture             Bosch Brake System Co., Ltd. F term (reference) 3D047 BB27 CC11 CC13 CC20 KK03                       LL01

Claims (7)

[Claims] 1. A cylinder housing having a cylinder hole, one end of which is closed and the other end of which is open, and which extends in the axial direction, and a communication passage communicating with a reservoir, and a cylinder housing of the cylinder housing, which is fitted into the cylinder hole, A piston that moves in the axial direction by defining a hydraulic chamber on the side and a cylinder housing side that seals the outer circumference of the piston, and a base portion and an inner circumference that is integral with the base portion. A cup-shaped seal ring having a lip portion and an outer peripheral lip portion, the inner and outer peripheral lip portions of which face the hydraulic chamber side, and the piston side, which communicates the communication passage and the hydraulic chamber. A plunger type master cylinder having a relief port, characterized by the following points. A When the master cylinder is in a non-operating state, the end surface of the base portion of the cup-shaped seal ring faces the opening of the relief port in the axial direction. B In addition to the first passage for feeding the working fluid from the reservoir through the communication passage to the hydraulic chamber, the first passage for tilting the outer peripheral lip portion of the cup-shaped seal ring to supply the working fluid, Between the end surface of the base portion of the cup-shaped seal ring and the member on the cylinder housing side adjacent to the end surface, there is a clearance passage that is always open to the relief port, and passes through the clearance passage, A second passage is provided for supplying hydraulic fluid through the relief port facing the clearance passage. 2. The gap passage is formed by integrally providing a protrusion on an end surface of a base portion of the cup-shaped seal ring or on at least one of the adjacent members on the cylinder housing side. Master cylinder. 3. The master cylinder according to claim 1, wherein the clearance passage is formed by providing a recess in at least one of an end surface of a base portion of the cup-shaped seal ring and a member adjacent to the cylinder housing side. . 4. The gap passage is formed by combining a projection and a recess on an end surface of a base portion of the cup-shaped seal ring or / and a member adjacent to the base surface on the cylinder housing side. The master cylinder according to claim 1. 5. The adjacent member on the cylinder housing side is a guide member for guiding the piston, and the guide member has a through hole penetrating radially inward and outward, and the inner peripheral side of the guide member through the through hole. For supplying hydraulic fluid to the hydraulic chamber side from the third through the relief port
The master cylinder of claim 1, further comprising: 6. The cup-shaped seal ring is such that the free end of the inner peripheral lip contacts the side of the cylinder housing so that it does not move in the axial direction when the piston moves. The master cylinder according to any one of claims 1 to 5. 7. The end surface of the base portion of the cup-shaped seal ring when the master cylinder is in a non-operating state,
The master cylinder according to claim 1, wherein the opening of the relief port is partially closed in the axial direction, and the remaining portion of the opening is opened to face the relief port.