JP3636576B2 - Master cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a master cylinder used for a hydraulic brake system for vehicles.
[0002]
[Prior art]
As this type of prior art, for example, Japanese Patent Application No. 8-354052 previously proposed by the applicant of the present application is known, and will be described below with reference to FIG.
[0003]
A conventional master cylinder is generally indicated by 1, and a first piston 4 on the primary side and a second piston 5 on the secondary side are slidable with respect to a cylinder hole 3 formed in the cylinder body 2. Has been inserted. A first hydraulic chamber 6 is defined between the first piston 4 and the second piston 5, and a second hydraulic chamber 7 is defined between the second piston 5 and the bottom of the cylinder hole 3. Formed on the upper portion of the cylinder body 2 are a first boss portion 8 and a second boss portion 9 into which the connecting portions 10 and 11 of the hydraulic fluid reservoir are fitted and fitted with grommet seals 12 and 13, respectively. The first piston 4 and the second piston 5 are provided with center valve portions 14 and 15, and the center valve portions 14 and 15 are opened and closed according to the movement of the pistons 4 and 5 as is well known. The hydraulic pressure generated in the first and second hydraulic pressure chambers 6 and 7 is supplied to the wheel cylinder of each wheel from an output port (not shown). A pipe 24 having a check device 23 provided on the discharge side of a pump device 22 that is an external actuator and a pump device 22 is connected between the inside of the second boss portion 9 and the first hydraulic pressure chamber 6. The pump device 22 is driven at the time of wheel drive slip, cornering oversteering and understeering, and the pump pressure is introduced into the first hydraulic pressure chamber 6 so that the second piston 5 is moved to the second hydraulic pressure chamber 7 side. An automatic brake control system is obtained which obtains a predetermined braking force by being moved.
[0004]
In the first piston 4, a pin member 16 that is a part of the components of the center valve portion 14 is supported by a cylindrical support member 17 mounted on the outer peripheral portion of the first piston 4, and this support member 17 is a cylinder body. The movement toward the opening 2a side is restricted by the annular ring 18 attached to the second opening 2a. That is, the movement of the first piston 4 on the opening 2 a side is restricted by the annular ring 18. The annular ring 18 is supported by an annular guide member 19 that is attached to the opening 2 a and guides the movement of the first piston 4 by sliding contact with the outer periphery of the first piston 4. The positioning is performed by the retaining ring 20 engaged with the annular groove 21 on the inner wall surface of the end of the opening 2a.
[0005]
[Problems to be solved by the invention]
However, in the configuration of the conventional master cylinder 1, the movement of the first piston 4 to the cylinder body opening 2a side, that is, the prevention of the first piston 4 from coming out of the opening 2a is prevented from engaging with the annular groove 21. Since the stop ring 20 is used, when the external device (pump device) 22 is driven and the hydraulic pressure is introduced into the first hydraulic pressure chamber 6 during the automatic brake control, the large hydraulic pressure cannot be endured. There is a problem that the retaining ring 20 may be damaged. The retaining ring 20 is made of a C-shaped ring member, and even if the axial thickness is increased to increase the pressure resistance, the force required for elastic deformation (diameter reduction) is on the contrary. As a result, the assembling property of the cylinder body 2 to the opening 2a is deteriorated.
[0006]
The present invention has been made in view of the above-described problem, and prevents the retaining member that restricts the movement of the primary-side piston from being damaged by the hydraulic pressure from the external actuator (pump device) to reliably restrict the movement. It is an object of the present invention to provide a master cylinder that can be used.
[0007]
[Means for Solving the Problems]
The above-described problems include a cylinder body having an opening at one end and having a cylinder hole therein, a piston that is slidably inserted into the cylinder hole and defines a hydraulic chamber in the cylinder hole, and the liquid A communication passage that communicates between the pressure chamber and the reservoir and is opened and closed according to the movement of the piston; a throttle hole formed in the communication passage; and a retaining member that prevents the piston from coming out of the opening. And a master cylinder capable of introducing hydraulic pressure generated by an external actuator into the hydraulic pressure chamber, wherein the retaining member is capable of restricting movement of the piston toward the opening. An engaging portion that engages and a cylindrical portion that is screwed directly to the cylinder body on the opening side are integrally formed, and the piston penetrates the inner peripheral side of the retaining member. This piston Guide members for guiding the movement of the piston is housed by sliding contact with the outer periphery, the master cylinder the engagement portion, characterized in that disposed in the hydraulic pressure chamber side of the guide member, by Solved.
[0008]
The present invention relates to a retaining member for preventing the piston from coming out of the opening of the cylinder body, an engaging portion for engaging the piston so that movement of the piston toward the opening can be restricted, and a cylinder on the opening side. By integrally forming the cylindrical portion that is directly screwed to the main body, the hydraulic pressure introduced from the external actuator to the hydraulic pressure chamber is received by the cylinder main body without passing through the guide member. ing. Eliminating the possibility of retaining member and the guide member is damaged by this, it is possible to reliably prevent leakage of the piston from the opening.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 shows a center valve type master cylinder according to an embodiment of the present invention, and shows only a peripheral portion of a first piston on the primary side. A piston (first piston) 34 having an annular seal member 35 mounted on the outer peripheral portion is slidably inserted into a cylinder hole 33 formed in the cylinder body 32, and a front portion thereof (in the drawing) A hydraulic chamber (first hydraulic chamber) 36 is defined on the left side. A valve chamber 39 is defined by a recess 37 formed in a front portion of the piston 34 and a retainer 45 that is screwed to the recess 37 and supports one end of a return spring 44 that is stretched in the hydraulic chamber 36. In the valve chamber 39, a rubber valve seat 48, a valve seat support member 51 for supporting the valve seat 48, a poppet valve body 47, and the poppet valve body 47 are urged toward the valve seat. A valve spring 52 is disposed. The shaft portion of the poppet valve body 47 faces the inside of a long hole 64 formed in the body portion of the piston 34 in a direction orthogonal to the axial direction, and in the state shown in the figure, a pin member that penetrates the long hole 64. 46 is in contact with the valve 46 and opened.
[0011]
The pin member 46 is supported by an annular collar member 54 slidably attached to the outer periphery of the piston 34. The collar member 54 includes a collar 63 and a guide 55, both end portions of the pin member 46 are supported by the guide 55, and the outer peripheral portion thereof is covered with the side peripheral portion of the collar 63. Therefore, in the present embodiment, semicircular cutouts 63a, 63a, 63a as pin member insertion portions as shown in FIG. 2 and FIG. That is, for example, the pin member 46 is prevented from coming off by being formed at intervals of 120 degrees (see FIG. 3). The collar 63 and the guide 55 can move relative to each other. When the pin member 46 is assembled, the collar 63 is moved against the spring force of the spring member 53 supported at one end by the flange portion 34a of the piston 34. The semicircular pin member insertion portion 63a and the pin insertion portion (hole) of the guide 55 are aligned. In the present embodiment, the pin member insertion portions 63a are formed at three equal intervals to improve the assembling property of the pin member 46.
[0012]
A retaining member 50 according to the present invention is provided in the opening 32 a of the cylinder body 32 via a seal ring 56. The retaining member 50 includes an engaging portion 50a that can restrict the movement of the piston 34 toward the opening 32a, and a cylindrical portion 50b that is directly screwed to the cylinder body 32 on the opening 32a side. The engaging portion 50a and the cylindrical portion 50b are integrally formed. In the present embodiment, the engaging portion 50a can be engaged with the piston 34 via the guide 55 of the collar member 54 described above. An annular guide member 49 through which the piston 34 penetrates is accommodated on the inner periphery of the retaining member 50 via a seal ring 59, and the inner periphery of the guide member 49 is brought into sliding contact with the outer periphery of the piston 34. The movement of the piston 34 is guided. As shown in FIG. 1, the engaging portion 50 a of the retaining member 50 is disposed closer to the hydraulic chamber 36 (left side in FIG. 1) than the guide member 49.
[0013]
One connection portion 40 of a hydraulic fluid reservoir (not shown) is fitted to a boss portion 38 formed on the upper portion of the cylinder body 32 via a grommet seal 42, and the inside of the hydraulic fluid reservoir (liquid storage chamber) is liquid-filled. Communication with the pressure chamber 36 is possible. That is, in the illustrated brake non-operating state, the center valve mechanism is open, so that the inside of the hydraulic fluid reservoir includes the replenishment chamber 68, the long hole 64, the periphery of the shaft portion of the poppet valve body 47, the valve chamber 39 and Although it is possible to communicate with the hydraulic pressure chamber 36 via a communication passage formed by a throttle hole 45a formed in the retainer 45, when the brake is actuated by the driver's brake operation, the piston 34 moves toward the hydraulic pressure chamber 36. The center valve mechanism is closed by the movement so that the communication passage is blocked. Also, during predetermined automatic brake control that is performed during wheel drive slip, cornering, oversteering, or understeering, hydraulic fluid in the hydraulic fluid reservoir is pressurized by a pump device (not shown) that is an external actuator. Supply to the chamber 36 is possible.
[0014]
A negative pressure type brake booster 70 indicated by a one-dot chain line in the drawing is connected to the opening 32a side of the cylinder body 32. At this time, the space between the negative pressure chamber (not shown) of the negative pressure type brake booster 70 and the atmosphere (external) is sealed by the seal ring 66 attached to the outer peripheral portion of the retaining member 50. Further, the space between the replenishment chamber 68 and the atmosphere is sealed by an annular first sealing member 57 that is mounted adjacent to the guide member 49 on the inner periphery of the retaining member 50, and is mounted on the step portion of the guide member 49. The annular second sealing member 58 seals between the negative pressure chamber of the negative pressure brake booster 70 and the atmosphere. The first and second sealing members 57 and 58 communicate with each other through a through hole 71 formed in the guide member 49 and a through hole 72 formed in the retaining member 50. Further, the guide member 49 and the second sealing member 58 are positioned by the annular member 61 and the ring member 62.
[0015]
This embodiment is configured as described above. Next, this operation will be described.
[0016]
When the brake control by the driver's brake operation, that is, the human brake control is performed from the illustrated brake non-operating state, the piston 34 is moved to the hydraulic pressure chamber 36 side. At this time, the collar member 54 that supports the pin member 46 moves relative to the piston 34 by the biasing force of the spring member 53 while the piston 34 moves by a predetermined distance, so that the poppet valve body 47 is securely attached to the valve seat 48. The brake fluid pressure is generated in the hydraulic pressure chamber 36 as is known. Further, the second piston (not shown) is also moved by the movement of the piston 34 to generate the brake hydraulic pressure in the second hydraulic pressure chamber.
[0017]
When the braking force is released by releasing the brake operation by the driver, the piston 34 is moved to the replenishment chamber 68 side by the spring force of the return spring 44. At this time, first, the collar member 54 contacts the engaging portion 50 a of the retaining member 50, and then the shaft portion (end portion) of the poppet valve body 47 contacts the pin member 46. As a result, the poppet valve body 47 is separated from the valve seat 48 and the center valve mechanism is opened. The movement of the piston 34 is restricted by the engaging portion 50 a of the retaining member 50 through the guide 55 of the collar member 54 after the peripheral wall portion of the long hole 64 and the pin member 46 are in contact with each other.
[0018]
During over-steering or under-steering during wheel drive slip or cornering, brake fluid pressure is introduced into the fluid pressure chamber 36 by a pump device (not shown) as an external actuator, and predetermined automatic brake control is performed. At this time, the center valve mechanism of the piston 34 is in an open state, but the flow of the pump pressure introduced into the hydraulic chamber 36 to the supply chamber 68 side is restricted by the throttle hole 45a. The two pistons are moved, and the brake fluid pressure is generated in the second fluid pressure chamber.
[0019]
In addition, during the automatic brake control, the piston 34 in the non-actuated state shown in the drawing receives the hydraulic pressure introduced into the hydraulic pressure chamber 36, that is, the discharge pressure of the pump device. At this time, the piston 34 receives a force acting on the cylinder body opening portion 32a side, and this acting force is brought into contact with the peripheral wall portion of the elongated hole 64 and the pin member 46, and the retaining member 50 as described above. It replaces with the contact force of the engaging part 50a and the guide 55 of the collar member 54. Therefore, in the present embodiment, the retaining member 50 (exactly its cylindrical portion) is screwed directly to the cylinder body 32, so that the abutting force can be reliably supported. In other words, a large discharge pressure of the pump device acting on the piston 34 during the automatic brake control is received by the cylinder body 32 without the guide member 49 being interposed .
[0020]
Therefore, according to the present embodiment, even during automatic brake control in which a large pump pressure acts on the piston 34, there is no risk of damage to the retaining member 50 and the guide member 49 , and the piston from the opening 32 a of the cylinder body 32 is eliminated. It is possible to reliably prevent the piston 34 from being pulled out and to reliably restrict the movement of the piston 34.
[0021]
The embodiment of the present invention has been described above. Of course, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.
[0022]
For example, in the above embodiment, the center valve type master cylinder in which the valve body 47 is arranged on the central axis of the piston 34 is applied. Instead, for example, the center cylinder type master cylinder is provided on the cylinder body side as the piston moves. The present invention is also applicable to a conventional master cylinder that opens and closes the communication hole.
[0023]
Further, in the above embodiment, the annular collar member 54 that supports both ends of the pin member 46 that is one component of the center valve mechanism is constituted by the two members of the collar 63 and the guide 55. It is also possible to configure with these members. Furthermore, it is of course possible to increase or decrease the number of pin member insertion portions 63a.
[0024]
【The invention's effect】
As described above, according to the master cylinder of the present invention, the retaining member that prevents the piston from coming off from the opening of the cylinder body engages with the piston so that the movement of the piston toward the opening can be restricted. Since the engaging portion and the cylindrical portion that is directly screwed to the cylinder main body on the opening side are integrally formed, the hydraulic pressure introduced from the external actuator to the hydraulic pressure chamber is received by the cylinder main body. can be, by eliminating the possibility of this by retaining member and the guide member is damaged, it can be prevented reliably escape of the piston from the opening.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a main part of a master cylinder according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing one component of a collar member according to the present invention.
3 is a view taken in the direction of arrow [3]-[3] in FIG. 2;
FIG. 4 is a cross-sectional view showing the whole of a conventional master cylinder.
[Explanation of symbols]
32 Cylinder body 32a Opening portion 33 Cylinder hole 34 Piston 36 Hydraulic chamber 45a Restriction hole 46 Pin member 49 Guide member 50 Retaining member 50a Engaging portion 50b Tubular portion 54 Color member 63a Pin member insertion portion

Claims (4)

A cylinder body having an opening at one end and having a cylinder hole therein; a piston that is slidably inserted into the cylinder hole and defines a hydraulic chamber in the cylinder hole; the hydraulic chamber and a reservoir; A communication passage that opens and closes according to the movement of the piston, a throttle hole formed in the communication passage, and a retaining member that prevents the piston from coming off from the opening, In the master cylinder that can introduce the hydraulic pressure generated by the external actuator to the hydraulic chamber,
The retaining member includes an engaging portion that engages with the piston so that movement of the piston toward the opening side can be restricted, and a cylindrical portion that is directly screwed to the cylinder body on the opening side. Formed integrally ,
A guide member that guides the movement of the piston by sliding in contact with the outer periphery of the piston is housed on the inner peripheral side of the retaining member, and the engaging portion is the guide member. The master cylinder is arranged closer to the hydraulic pressure chamber . The master cylinder is a center valve type master cylinder, and a pin member that is a part of the constituent elements of the center valve passes through the piston in a direction perpendicular to the axis of the piston. end of the member is supported by the collar annular member which is fitted on the outer periphery of the piston, to claim 1, wherein the engaging portion and the piston is adapted to be engaged through said collar member The master cylinder described. The master cylinder according to claim 2 , wherein a plurality of pin member insertion portions are formed in the annular collar member, and the pin member insertion portions are formed at positions other than on the same diameter. The master cylinder according to claim 3 , wherein the pin member insertion portion is formed by a semicircular cutout on one end side of the annular collar member.

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