JP3448765B2 - Center valve type master cylinder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center valve type master cylinder used for a hydraulic brake or clutch of a vehicle or the like, and more particularly to a technique for preventing an annular seal member made of an elastic material from being eaten.

[0002]

BACKGROUND OF THE INVENTION In general, a center valve type master cylinder has an advantage that a rubber-based seal member is less damaged than a conventional type cylinder having a valve on an outer peripheral portion of a piston. However, even with the center valve type, the tip of the seal member is located at the center of the piston when the fluid flows from the hydraulic chamber side to the hydraulic fluid reservoir side when the valve element is slightly separated from the valve seat. The so-called bite, which is sucked into the holes of, is likely to occur.

As a technique for preventing such a center valve from being eaten, there is a technique in which the inner peripheral side of an annular seal member made of an elastic material is supported by a cylindrical retainer made of a material having a rigidity higher than that of the elastic material of the seal member. Known (for example, JP-A-9-150728, JP-A-10-
95328 or JP-A-11-59393).
In these technologies, the front end of the annular seal member on the hydraulic chamber side is located closer to the hydraulic chamber than the front end of the retainer on the inner circumference in order to obtain an effective valve opening / closing function. . Further, by restraining the annular seal member from the inner and outer circumferences and the front and rear in the axial direction, the posture thereof is maintained in a constant state. Incidentally, JP-A-11
As shown in FIG. 2 of No. -59393, the restraint on the annular seal member from the front side, that is, the restraint from the hydraulic pressure chamber side is in the form of eliminating the restraint in order to avoid unnecessary deformation of the seal member. There is. In addition, JP-A-10
As shown in FIG. 3 of -95328, a bulging portion is provided on the outer periphery of the rear end portion of the annular seal member so as to seal between the seal member and the side wall of the recess of the piston.

[0004]

By the way, such a center valve type master cylinder is used as a hydraulic pressure generation source in a normal brake based on the pedal operation of the driver, and is not related to the pedal operation of the driver. Automatic braking, for example, it is also used in an automatic braking system that detects the posture of the vehicle and actuates a pressurizing means such as an external pump based on the detection result to supply the hydraulic fluid to the hydraulic chamber inside the cylinder. . Therefore, the annular seal member in the center valve is exposed to a wide range of hydraulic pressure. Therefore, depending on the hydraulic pressure generated in the hydraulic chamber, the hydraulic pressure propagates between the outer periphery of the distal end and the side wall of the recess of the piston, with respect to the distal end of the annular seal member facing the hydraulic chamber, It is conceivable that the propagated hydraulic pressure acts to incline the tip of the annular seal member inward in the radial direction. When the head portion of the valve body is seated on the annular seal member that receives such an acting force, a part of the annular seal member that serves as the valve seat may be caught and damaged.

A first object of the present invention is to consider the hydraulic pressure propagation to the outer periphery of the tip portion of such an annular seal member, minimize the hydraulic pressure propagation, and effectively prevent the annular seal member from being eaten. To prevent. A second object of the present invention is to firmly support the tip end portion of the annular seal member from inside and outside in the radial direction and eliminate the need to restrain the tip end portion from the hydraulic chamber side.

[0006]

According to the present invention, when a hydraulic seal for preventing hydraulic pressure from propagating from the hydraulic chamber to the bottom side of the recess is provided between the side peripheral wall of the recess of the piston and the annular seal member,
The hydraulic seal is provided in the vicinity of the front end of the annular seal member on the side of the hydraulic chamber, and particularly at a position closer to the hydraulic chamber than the thickness of the front end of the annular seal member. As a result, even though the tip of the annular seal member is protruded toward the hydraulic chamber side from the tip of the retainer, the tip of the annular seal member protruding toward the hydraulic chamber is It is effectively prevented from tilting inward in the radial direction due to the force caused by. This is because when the length to the support point is smaller than the thickness of the object, the object will tilt around the support point even if a force to tilt the object is applied to the tip of the object. Is usually not.

The hydraulic seal can be obtained in the following several forms by changing the shape of the annular seal member, the shape of the retainer or the material. Of course, one of those forms can be applied alone, or a plurality of forms can be applied together. Compared to the annular seal member made of rubber material, the retainer made of metal material with higher rigidity is easier to process,
In practice, the form in which the retainer is processed is preferable. a. A configuration in which a bulged portion having an outer shape larger than the inner diameter of the side peripheral wall of the recess on the piston side in the free state is provided on the outer periphery of the annular seal member b. Form in which a lip is provided at the tip of the annular seal member c. A configuration in which the tip portion of the retainer, which faces the hydraulic chamber, is configured to generate a biasing force outward in the radial direction with respect to the annular seal member located on the outer periphery of the retainer. This can be done by making the diameter partly larger than the part adjacent to it, or by making the retainer of a spring material and preloading the tip of the retainer. Also in the form of c, from the viewpoint of cost, the former in which the shape of the retainer is changed is preferable.

The present invention can also be understood as a concept of supporting the vicinity of the tip of the annular seal member located on the outer periphery of the retainer so as to be sandwiched from inside and outside in the radial direction. According to this support mode, it is possible to firmly hold the tip portion of the annular seal member that protrudes more toward the hydraulic chamber than the tip portion of the retainer. Therefore, it is not necessary to restrain the end surface of the tip portion of the annular seal member from the hydraulic chamber side. Therefore, the assembly of the center valve is facilitated, and a problem associated with restraint, for example, the problem that the position of the valve seat on the annular seal member side changes depending on the degree of restraint can be avoided.

The center valve type master cylinder of the present invention is a single or tandem type and further various braking systems such as front and rear type or X type piping, and anti-lock and anti-slip brake control devices. It can be applied to a wide range of things including or not including.

[0010]

[First Embodiment] FIG. 1 is an overall sectional view showing a tandem type brake master cylinder according to a first embodiment of the present invention. Further, FIG. 2 is an enlarged cross-sectional view showing an enlarged part of the center valve, and FIG. 3 is a component diagram of the annular seal member. Note that FIG. 1 shows the brake non-operating state and the center valve is open, whereas FIG. 2 shows the brake operating state, and the center valve is closed.

First, referring to FIG. 1, let us look at the overall structure of a tandem brake master cylinder 10.
The master cylinder 10 includes, along the axial direction, a primary portion 10P including a first center valve and a secondary portion 10S including a second center valve having the same configuration as the first center valve. The primary portion 10P is for the front wheel braking device, and the secondary portion 1
0S is for a rear wheel brake device with an antilock brake function. The master cylinder 10 includes a cylinder body 14 in which a cylinder hole 12 having a uniform inner diameter is formed. The front end 14f of the cylinder body 14 is closed, and a return spring 162 for a secondary piston, a secondary piston 202, a return spring 161 for a primary piston, and a primary piston 201 are sequentially arranged from the closed side. A push rod (not shown) is arranged behind the.

The primary and secondary pistons 201 and 202 have lip seal members 31a and 31b; 32a and 32b, respectively, which are separated in the front-rear direction. Each of these lip seal members includes a cylinder body 14
The inner peripheral surface of each of the pistons 201 and 202 is sealed, whereby the second hydraulic chamber 42 is provided in front of the secondary piston 202 and the first hydraulic fluid chamber 42 is provided between the secondary piston 202 and the primary piston 201. The hydraulic chamber 41 is partitioned. Each of the center valves 50 on the primary side and the secondary side includes the first or second center valve 50 inside the cylinder hole 12.
The fluid pressure chambers 41, 42 and the hydraulic fluid reservoir (not shown) in the upper part of the cylinder body 14 are communicated with and cut off from each other.

Next, referring to FIG. 2 in addition to FIG. 1, let's look at the portion of the center valve 50. Each hydraulic chamber 41,
There is a recess 300 at the end of each piston 201, 202 facing 42. The recess 300 is formed in each hydraulic chamber 41, 4
2, and extends from the opened portion to the inside of each piston 201, 202 along the axis of the cylinder body 14. The recess 300 has a diameter slightly larger on the side closer to the opening than on the inner side. The bottom of the recess 300 is the piston 2
01, 202 through the central hole 302, the piston guide hole 304 following the central hole 302, the side holes 306 on the outer periphery of the pistons 201, 202, etc., and the inside of a working fluid reservoir (not shown) in the upper portion of the cylinder body 14. The piston guide hole 304 is a hole for receiving the stopper member 308 as a valve opening means, and penetrates the pistons 201 and 202 by itself.

In the recess 300, the respective constituent parts of the center valves 50 on the primary side and the secondary side are located. The poppet type valve body 52 at the center includes a head portion 52h and a rod portion 52r extending from the head portion 52h.
It fits in the central hole 302 of 202 and is movable in the direction along the axis. The valve spring 53 contacts the head portion 52h of the valve body 52 and pushes the valve body 52 toward the stopper member 308. One spring bearing of the valve spring 53 is the head portion 52h itself of the valve body 52, and the other spring bearing of the valve spring 53 is a stopper ring 70 fitted in the opening of the recess 300. The stopper ring 70 itself is the C-shaped ring 7
It is positioned closer to the opening of the recess 300 than the C-shaped ring 72 while being prevented from coming off by 2. When the stopper ring 70 is assembled in the recess 300,
The insertion position is regulated by the step portion 300s in the middle of the recess 300, and the position is regulated by the C-shaped ring 72 after the assembly.

In the valve body 52 pushed by the valve spring 53, the movement of the rear end of the rod portion 52r is restricted by the stopper member 308 at a normal time when the brake operation is not performed, and the head portion 5 is moved.
Keep 2h away from the valve seat to keep the valve open. In addition, the pistons 201 and 202 are connected to the cylinder body 1 in accordance with the brake operation.
When moving to the side of the front end 14f of No. 4, the valve body 52 is released from the restriction from the stopper member 308 and seats on the valve seat, whereby the valve body is closed. When the poppet-type valve body 52 is seated on and off, the valve body 52 moves slightly in the axial direction, so that a guide member 80 for guiding the rod portion 52r is provided at the innermost part of the recess 300. The guide member 80 has an annular shape, and includes a guide hole 82 into which the rod portion 52r is inserted in the central portion, and a liquid passage 84, which serves as a flow path for the working liquid, on the radial outside of the guide hole 82.

A component for forming a valve seat on which the head portion 52h of the valve body 52 is seated / separated is a step portion 3 in the middle of the recess 300.
It is located in a portion deeper than 00s, that is, in a small diameter portion in the recess 300. The components of the valve seat are the guide member 80.
And a tubular retainer 90 adjacent to each other, and an annular seal member 100 located on the outer periphery of the retainer 90.

The tubular retainer 90 is made of metal, and has a large-diameter flange 9 that is outwardly attached to a rear end that contacts the guide member 80.
2, on the front end farthest from the guide member 80,
The thick wall portion 94 having a slightly thicker outer diameter than the adjacent portions, and the thick wall portion 9 further.
4 and a large-diameter flange 92 between the small-diameter flange 96 facing outward
Including each. The large-diameter flange 92 has a size that substantially fits the inner circumference of the recess 300. The retainer 92 retains its posture in the recess 300 while the outer periphery of the large-diameter flange 92 fits into the inner periphery of the recess 300, and the rear end face thereof is supported by the guide member 80. You can The retainer 90 is a component for integrally supporting the annular seal member 100 and holding it at a predetermined position in the recess 300. Large diameter flange 92 and small diameter flange 9
6 is a ring-shaped seal member 1 between them in cooperation with each other.
The mounting groove 926 for mounting the rear part 110 of 00 is defined. The thick portion 94 at the tip of the retainer 92 supports the front portion 120 of the annular seal member 100 by pressing the front portion 120 against the side peripheral wall of the recess 300. In addition, the end surface of the tip portion of the retainer 92 projects toward the hydraulic chambers 41 and 42 on the outer peripheral side as compared with the inner peripheral side, whereby the inner peripheral edge 90i of the retainer 90 constitutes the second valve seat. The second valve seat 90i on the retainer 90 side is
The poppet-type valve body 52 is a valve seat that is seated immediately after seated on the first valve seat 100i at the tip of the annular seal member 100. The second valve seat 90i stabilizes the seated posture of the poppet-type valve body 52, thereby ensuring the blocking function of the first valve seat 100i.

The annular seal member 100 including the first valve seat 100i is made of rubber that is elastically deformable, and when it is assembled in the recess 300, it is attached to the retainer 90 in advance, and is integrated with the retainer 90 into the recess 300. Is inserted. The ring-shaped seal member 100 has a total length of about 6 mm, and has a groove 102 extending over the entire circumference in the middle portion of the inner circumference, and the groove 102 is divided into a front portion 120 and a rear portion 110 substantially in front and back. Front portion 12 with first valve seat 100i
0 and a bulge 112 of about 0.2 to 0.3 mm on the outer circumference
The thickness of each of the rear portions 110 provided with is almost 2 mm, which is almost the same, but the inner diameters of the respective portions 120 and 110 are slightly different from each other in accordance with the diameters of the corresponding portions of the retainer 90. However, the front and rear parts 120,
The inner diameter of 110 is uniform in the axial direction. The annular seal member 100 includes a rear portion 1 provided with a bulging portion 112.
10 is placed in the mounting groove 926 of the retainer 90, and therefore, the small diameter flange 96 of the retainer 90 is placed in its own groove 102 and is set on the outer periphery of the retainer 90. The rear portion 110 of the annular seal member 100 has the recess 3
The size of the gap between the side peripheral wall of 00 and the outer periphery of the mounting groove 926 of the retainer 90 is thicker by the amount of the bulging portion 112. Therefore, when the annular seal member 100 set in the retainer 90 is assembled in the recess 300, as can be seen from FIG. 2, the rear portion 110 of the annular seal member 100 elastically deforms the bulging portion 112 to attach the mounting groove. It is firmly held at 926. Also, the front portion 120 of the annular seal member 100 is not pressed from the retainer 90 in the portion close to the groove 102, but the portion fitted in the thick portion 94 receives the urging force from the retainer 90 side toward the radial outside. It is held as firmly as the rear portion 110.

[0019] Now, before lateral portion of the annular seal member 100 1
Attention should be paid to the end portion of 20, that is, the front end portion facing each of the hydraulic chambers 41 and 42. The tip portion projects about 1 mm toward the respective hydraulic chambers 41, 42 from the thick portion 94 at the end of the retainer 90, and is free from the retainer 90. Length of the protruding portion is smaller than the thickness of the front side portion 120 of the annular seal member 100. In such a tip portion, there is a portion 114 having an arc-shaped cross section inward in the radial direction,
A part of the portion 114 becomes the first valve seat 100i. On the other hand, a lip 116 extending toward the hydraulic chambers 41, 42 is provided radially outward of the tip portion. The length of the lip 116 is 1 mm
It is weak and before insertion into the recess 300 (state shown in broken lines in FIG. 2 and state shown in FIG. 3) the front portion 120.
Similar to the bulging portion 112, the outer diameter is larger than the other portions of the annular seal member 100. However, inside the recess 300, the diameter is the same as that of the other portion of the annular seal member 100, and the side peripheral wall of the recess 300 is sealed. That is, the lip 116 constitutes a hydraulic seal that prevents hydraulic pressure from propagating from the hydraulic chambers 41, 42 to the bottom side of the recess 300. Since the lip 116 receives the pressing force by the hydraulic pressure of the hydraulic chambers 41 and 42 in addition to the force associated with its own elastic deformation, the lip 116 surely exhibits the sealing function. Therefore, the tip portion of the annular seal member 100 exhibits a constant posture even if the hydraulic pressure in the hydraulic chambers 41 and 42 changes, and the center valve 50 is effectively prevented from being eaten. .

[0020]

[Second Embodiment] FIG. 4 shows a second embodiment of the present invention and is a partially enlarged sectional view corresponding to FIG. 2 of the first embodiment. In the first embodiment, the lip 116 provided on the end surface of the tip of the annular seal member 100 constitutes the hydraulic seal, but in the second embodiment, the outer periphery of the front portion 120 of the annular seal member 100 is formed. To
Bulging part 1 similar to the bulging part 112 in the rear part 110
22 is provided, and the bulging portion 122 constitutes a hydraulic seal. Bulging portion 122 of front portion 120
Is smaller than the bulging portion 112 of the rear portion 110,
Since the retainer 90 is located just outside the thick portion 94 in the radial direction, the force due to the elastic deformation of the bulging portion 122 itself and the pressing force generated by the thick portion 94 are combined to generate a reliable sealing function. .

[Brief description of drawings]

FIG. 1 is an overall cross-sectional structural diagram of a master cylinder showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a center valve portion of the master cylinder of the first embodiment in an enlarged manner.

FIG. 3 is a sectional view of an annular seal member used in the first embodiment.

FIG. 4 is a view showing a second embodiment of the present invention and is an enlarged sectional view showing a center valve portion in an enlarged manner.

[Explanation of symbols]

10 Master cylinder 14 Cylinder body 201,202 piston 300 recess 41,42 Hydraulic chamber 50 center valve 52 valve body 80 Guide member 90 retainer 100 annular seal member 116 lip 122 bulge

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-95328 (JP, A) JP-A-11-208446 (JP, A) JP-A-11-59393 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B60T 11/00-11/34

Claims (7)

(57) [Claims] 1. A cylinder body having a cylinder hole, a piston which slidably fits in the cylinder hole and defines a hydraulic chamber therein, and a piston which slides in the cylinder hole. A center valve type master cylinder having a center valve that connects and disconnects the fluid pressure chamber and the working fluid reservoir side, the center valve having a penetrating passage that allows the fluid pressure chamber to communicate with the working fluid reservoir side. An annular seal member that includes a hole and is disposed in a recess defined at the end of the piston on the hydraulic chamber side, and an annular seal member formed of an elastic material and supported by the outer periphery of the retainer and the side peripheral wall of the recess. A head portion that is attached to and detached from an end portion of the annular seal member that is located closer to the hydraulic chamber than the hydraulic chamber-side tip portion of the retainer, and is integrated with the head portion, In a master cylinder having a valve body that includes a rod portion that fits with a gap in a through hole, between the side peripheral wall of the recess and the annular seal member, from the hydraulic chamber to the bottom side of the recess. There is a hydraulic seal that blocks the propagation of hydraulic pressure, and the hydraulic seal is located near the tip of the annular seal member on the hydraulic chamber side , and
From the position of the pressure seal, the end of the annular seal member on the hydraulic chamber side
The distance to the end of the part is the diameter of the tip of the annular seal member.
A center valve type master cylinder characterized by being smaller than the thickness of the wall in the direction . 2. The hydraulic seal is configured by providing a bulge portion having an outer diameter larger than an inner diameter of a side peripheral wall of the recess in a free state on an outer periphery of the annular seal member.
The master cylinder according to claim 1. 3. The master cylinder according to claim 1, wherein the hydraulic seal is constituted by a lip provided at a tip portion of the annular seal member. 4. The tip end portion of the retainer, which faces the hydraulic chamber, is configured to generate a biasing force outward in the radial direction with respect to the annular seal member located on the outer periphery of the retainer. 3 master cylinders. 5. The master cylinder according to claim 1, wherein, when the head portion of the valve body is seated on the end portion of the annular seal member, the head portion is also seated on the inner peripheral edge of the hydraulic chamber side end portion of the retainer. 6. The end surface of the end portion of the annular seal member on the hydraulic pressure chamber side has an inner peripheral side protruding toward the hydraulic pressure chamber side as compared to an outer peripheral side, whereas the retainer side on the hydraulic pressure chamber side. The master cylinder according to claim 1, wherein an outer peripheral side of the end surface of the tip portion is protruded toward the hydraulic chamber side as compared with an inner peripheral side. 7. A guide member for guiding the rod portion of the valve body is provided on the bottom side of the recess, the guide member is annular, and a guide hole into which the rod portion is inserted in the central portion, and a guide hole thereof. 2. The master cylinder according to claim 1, further comprising a liquid passage serving as a flow passage for the working liquid, on a radially outer side of the master cylinder.