JP4349718B2 - Center valve type master cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a center valve type master cylinder used in a hydraulic brake or clutch system of a vehicle or the like, and in particular, has a sufficient fluid passage for communication between a hydraulic chamber inside a cylinder body and a hydraulic fluid reservoir side. It relates to technology effective in securing.
[0002]
BACKGROUND OF THE INVENTION
In general, the master cylinder must have a valve mechanism for communicating and blocking between the hydraulic chamber inside the cylinder body and the external hydraulic fluid reservoir. In the center valve type master cylinder, there is a recess on one end of the piston facing the hydraulic chamber, and a cylindrical retainer is assembled in the recess, and the valve mechanism is located at the center of the space defined by the retainer and the recess. Is located. As shown in, for example, Japanese Patent Application Laid-Open No. 10-95328, the valve mechanism is generally located on the bottom side of the recess and the poppet valve body movable in the axial direction of the cylinder body, and the poppet valve body is separated and seated. A valve seat and a coil spring that urges the poppet valve body toward the valve seat are included. Here, the coil spring, which is a valve spring, has one end supported by the poppet valve body, while the other end is supported by a protruding portion protruding radially inward from the inner wall of the cylindrical retainer. Has been.
[0003]
By the way, when shortening the axial length of this type of master cylinder, each component of the center valve mechanism, which is an internal component, is inevitably downsized. As a result, when the pedal is suddenly released from the operating state of the master cylinder when the pedal is depressed and the master cylinder is deactivated, the problem of poor fluid replenishment from the hydraulic fluid reservoir to the hydraulic pressure chamber is a problem. May occur. Japanese Patent Application Laid-Open No. 10-226329 discloses that narrowing the space between windings of a coil spring, which is a valve spring, is one cause of the problem of liquid replenishment. In the operating state of the master cylinder, since the poppet valve body is seated on the valve seat, the coil spring is close to the natural length, and a relatively sufficient space is secured between the windings. However, since the negative pressure is generated in the hydraulic chamber at the time of releasing the pedal, the poppet valve body moves so as to compress the coil spring by the differential pressure between the negative pressure and the atmospheric pressure on the hydraulic fluid reservoir side. As a result, it is analyzed that the space between the windings of the coil spring, which is a part of the passage communicating the hydraulic pressure chamber and the hydraulic fluid reservoir side, is narrowed and the resistance of the fluid flow is increased. Based on this, the publication proposes a technique for providing a bypass passage for bypassing a passage between windings of a coil spring.
[0004]
[Problems to be solved]
Since the technology for providing the proposed bypass passage requires new processing for that purpose, a simpler solution is desired. Then, further investigations were made on the liquid replenishment property between the hydraulic chamber and the hydraulic fluid reservoir side, or the securing of the liquid passage, and a new matter was found. First, when the master cylinder is used in a low-temperature environment, the viscosity of the hydraulic fluid increases, so that such a problem of liquid replenishment is particularly remarkable, and it is important to ensure a sufficient liquid passage. That is. Secondly, with the compression of the coil spring, the space between the windings is narrowed, and there is a possibility that a situation occurs where the poppet valve element closes the liquid passage inside the retainer. I will explain the second item more specifically. In order to secure a larger liquid passage, there is a large central hole on the radially inner side of the protruding portion inside the retainer which is the other spring receiver of the coil spring. The end of the poppet valve element tends to enter the central hole, which may reduce the flow area of the central hole and impair the liquid flow.
[0005]
The present invention also provides a technique capable of ensuring a sufficiently large liquid passage for communication between the hydraulic pressure chamber and the hydraulic fluid reservoir side in consideration of the new findings as described above. For the purpose.
Another object of the present invention is to provide a technique capable of securing a fluid passage for communication between the fluid pressure chamber and the hydraulic fluid reservoir side by slightly modifying an existing one. .
Furthermore, the present invention further provides a technique capable of securing a fluid passage for communication between the fluid pressure chamber and the hydraulic fluid reservoir side by utilizing a coil spring itself that is a valve spring. Objective.
[0006]
Means of the Invention
In the present invention, the problem is solved by utilizing a specific form or shape of a coil spring that is a valve spring. By only changing the coil spring, it is possible to effectively secure a fluid passage for communication between the fluid pressure chamber and the hydraulic fluid reservoir.
A characteristic configuration according to the present invention is as follows.
A. A communication hole that communicates the hydraulic pressure chamber and the hydraulic fluid reservoir side is provided on the radially inner side of the protruding portion that supports the other end of the coil spring.
B. At the other end of the coil spring, there is a transverse portion where the end of the coil winding crosses in the radial direction of the coil spring.
C. When the end face of the poppet valve body facing the hydraulic pressure chamber bends the coil spring and hits the transverse part of the coil spring, a gap remains between the windings of the coil spring.
[0007]
One connecting hole in A is preferably provided at the center in order to facilitate processing. However, in addition to the central hole, a plurality of peripheral holes may be provided around the central hole. In addition, as the coil spring in B, various shapes such as a truncated cone shape, a cylindrical shape, and a sag shape can be applied. From the viewpoint that the poppet valve body moves stably, the hydraulic chamber side A frustoconical shape whose diameter increases toward is most preferable. The transverse part at the end of the winding of the coil preferably traverses the entire radial direction so as to completely traverse the end face of the poppet valve body. As long as it functions as a stopper for the poppet valve body to be moved to and does not adversely affect the spring characteristics of the valve spring, its end shape can be slightly shortened, or not only a straight line but also a curved line It can also be shaped.
Further, the crossing portion of the coil spring at C is sandwiched between the poppet valve body and the communication hole and functions as a spacer, and ensures a liquid flow path at the end face portion of the poppet valve body. In addition to such a spacer function, the crossing portion functions as a stopper for the poppet valve body, and ensures a necessary minimum gap (liquid flow path or space) between the windings of the coil spring.
[0008]
The present invention can be applied to various master cylinders including a center valve mechanism. The master cylinder may be a clutch, a brake, a single type, or a tandem type. In the case of the tandem type, the present invention can be applied to at least one of the primary side and the secondary side. Further, the present invention is not limited to such an automatic control brake as in, for example, Japanese Patent No. 3050805, that is, in addition to a normal brake operation in which the driver raises the hydraulic pressure in the hydraulic pressure chamber by operating the pedal. Needless to say, the present invention can be applied to an apparatus including an automatic brake operation in which the pump device automatically raises the hydraulic pressure in the hydraulic pressure chamber without a pedal operation.
[0009]
【Example】
FIG. 1 is an overall sectional view showing a tandem type brake master cylinder according to an embodiment of the present invention.
In the tandem master cylinder 10, the valve mechanisms of both the primary part 100 and the secondary part 200 are center valves. 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 the secondary piston return spring 162, the secondary piston 202, the primary piston return spring 161, and the primary piston 201 are sequentially arranged from the closed side, and a push (not shown) is arranged behind the primary piston 201. A rod is placed.
The primary and secondary pistons 201 and 202 have lip-type seal rings 31a and 31b; 32a and 32b, respectively, at locations separated in the front-rear direction. Each of these seal rings seals between the inner peripheral surface of the cylinder main body 14 and each of the pistons 201 and 202, so that the second hydraulic pressure chamber 42 and the primary piston 201 are placed in front of the secondary piston 202. A first pressure chamber 41 is partitioned forward.
[0010]
The primary-side valve mechanism 50 and the secondary-side valve mechanism 70 communicate and block between the first or second hydraulic chambers 41 and 42 and the hydraulic fluid reservoir (not shown) on the cylinder body 14. To do. Now, when the primary piston 201 is pushed through a push rod (not shown), the valve mechanism 50 of the primary piston 201 is cut off and a hydraulic pressure is generated in the first hydraulic chamber 41. Then, the secondary piston 202 is moved by the hydraulic pressure in the first hydraulic chamber 41, and hydraulic pressure is generated in the second hydraulic chamber 42 by the shut-off function of the secondary side valve mechanism 70.
[0011]
Both valve mechanisms 50, 70 are provided in a recess 300 provided at the end of each piston 201, 202 facing each hydraulic chamber 41, 42, and inside cylindrical retainers 91, 92 assembled in the recess 300. Inside. 2 clearly shows the primary side valve mechanism 50, and FIG. 3 clearly shows the secondary side valve mechanism 70. As can be seen from these figures, the configuration of each valve mechanism 50, 70 itself is substantially the same, so the corresponding components are assigned the same reference numerals. The primary side retainer 91 includes an outward flange 91f sandwiched between the primary piston 201 and the cage member 210, whereas the secondary side retainer 92 entirely enters the recess 300. Yes. Attention should be paid to the retainer 92 on the secondary side. The retainer 92 has a claw portion 92c on the outer peripheral portion corresponding to the plurality of grooves 300d near the opening of the recess 300. The retainer 92 is assembled to the secondary piston 202 when the claw portions 92c fit into the groove 300d. In particular, the end surface of the retainer 92 and the end surface of the secondary piston 202 are set to be flush with each other when the claw portions 92c are properly fitted in the grooves 300d. Therefore, even when the claw portion 92c is not properly fitted in the groove 300d during assembly, the claw portion 92c and the groove 92c are formed by bottoming the secondary piston 202 on the front end 14f of the cylinder body 14 after assembly. The fit with 300d can be optimized.
[0012]
The recess 300 is along the axis of the cylinder body 14, and the inner diameter of the recess 300 is large at a part of the opening and the others are almost uniform. The bottom of the recess 300 communicates with the inside of the hydraulic fluid reservoir through the center hole 301 of the pistons 201 and 202, the intermediate hole 303 following the center hole 301, and the side peripheral hole 305 on the outer periphery of the pistons 201 and 202. The intermediate hole 303 is a hole for receiving a shaft member as valve opening means, and itself penetrates the pistons 201 and 202. The secondary-side shaft member 3072 is fixed to the cylinder body 14, whereas the primary-side shaft member 3071 is supported by the piston 201 via a guide member. Needless to say, the shaft members 3071 and 3072 function as stoppers for holding the valve mechanisms 50 and 70 in the valve-opened state when the master cylinder 10 is inactive.
[0013]
Now, attention is focused on the portions of the center valve mechanisms 50 and 70 located in the recess 300. The poppet valve body 52 includes a head portion 52h and a rod portion 52r extending from the head portion 52h. The rod portion 52r fits in the center hole 301 of the pistons 201 and 202 and is movable in the direction along the axis. The head portion 52h of the poppet valve body 52 has a conical coil spring 53 that is a valve spring, and pushes the poppet valve body 52 toward the shaft members 3071 and 3072. A portion surrounding the opening of the central hole 301 of the pistons 201 and 202 constitutes a valve seat 60 on which the poppet valve body 52 is seated. The valve seat 60 is located at one end on the inner peripheral side of the valve seat sleeve 630 made of rubber. The valve seat sleeve 630 is mounted on the outer periphery of an inner peripheral retainer 610 made of, for example, metal, which has higher rigidity than rubber.
[0014]
When the poppet valve body 52 is pushed by the coil spring 53, the movement of the rear end of the rod portion 52r is restricted by the shaft members 3071 and 3072 and the head portion 52h is separated from the valve seat and kept in a valve-open state in a normal state without a brake operation. . Further, when the pistons 201 and 202 move to the front end 14 f side of the cylinder body 14 in accordance with the brake operation, the poppet valve body 52 is released from the restriction from the shaft members 3071 and 3072 and is seated on the valve seat 60. It will be closed by it. When the poppet valve body 52 is seated and separated, the valve body 52 moves 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 enters the center portion, and a liquid passage hole 84 serving as a flow path for the hydraulic fluid on the radially outer side of the guide hole 82. Accordingly, around the rod portion 52 r of the poppet valve body 52, there is a liquid passage having a sufficient flow passage area such as an annular passage between the inner peripheral retainer 610 and the liquid passage hole 84 of the guide member 80. Therefore, the hydraulic fluid can always flow smoothly between the end of the rod portion 52r of the poppet valve body 52 and the head portion 52h. That is, when the poppet valve body 52 is in a valve open state (state shown in the figure) in which the head portion 52r is separated from the valve seat 60, in a valve closed state in which the head portion 52r is seated on the valve seat 60, or As described above, the same applies to any case where the poppet valve body 52 compresses the coil spring 53 in response to sudden release of the pedal that has been depressed.
[0015]
On the other hand, there is another story between the stepped portion of the head portion 52 h that supports one end of the coil spring 53 and the protruding portion 93 of the retainers 91 and 92 that supports the other end of the coil spring 53. The coil spring 53 changes the space between the windings according to the movement of the poppet valve body 52. If the movement of the poppet valve body 52 in the axial direction is not limited as in the past, adjacent windings may be brought into close contact with each other, and the space between them may be zero. In this regard, in the present invention, as shown in FIG. 4, a transverse portion 538 that traverses in the radial direction of the coil spring 53 is provided at the end of the coil winding on the side supported by the retainers 91 and 92, and the transverse portion By 538, the maximum movement amount of the poppet valve body 52 to the hydraulic pressure chamber side is regulated. As a result, when the end surface 528 of the poppet valve body 52 on the head portion 52r side hits the crossing portion 538, a predetermined space or more is secured between the windings of the coil spring 53.
[0016]
The transverse portion 538 of the coil spring 53 has a form in which one end of the coil spring 53 is extended. It is preferable that the crossing portion 538 completely crosses the end surface 528 of the poppet valve body 52 on the head portion 52r side, and both end portions 538a and 538b are placed on the protruding portions 93 of the retainers 91 and 92. . Thereby, when receiving a force from the poppet valve body 52, the posture of the transverse portion 538 can be always maintained in a state orthogonal to the axial direction. Even if the end surface 528 of the poppet valve body 52 on the head portion 52r side hits the crossing portion 538, the coil spring 53 is interposed between the end surface 528 on the head portion 52r side and the protruding portion 93 of the retainers 91 and 92. There is a distance of the wire diameter. Therefore, the head portion 52 r of the poppet valve body 52 does not block the central hole 95 on the inner periphery of the protruding portion 53, and a liquid flow path through the central hole 95 is ensured from the space between the windings of the coil spring 53. Can do.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing an example of a master cylinder according to an embodiment of the present invention.
FIG. 2 is an enlarged view showing a portion surrounded by a circle 2 in FIG.
FIG. 3 is a partially enlarged view of a secondary part in FIG. 1;
4 is a cross-sectional view taken along line 4-4 of FIG.
[Explanation of symbols]
10 master cylinder 12 cylinder hole 14 cylinder body 201, 202 piston 300 recess 300d groove 41, 42 hydraulic chamber 50, 70 valve mechanism 52 poppet valve body 53 coil spring (valve spring)
538 Crossing part 60 Valve seat 91, 92 Retainer 92c Claw part 93 Projection part 95 Center hole (communication hole)

Claims (6)

A cylinder main body having a cylinder hole along the axial direction inside, a piston which is slidably inserted into the cylinder hole and divides the hydraulic chamber in the cylinder hole together with the cylinder main body, and the piston And a valve mechanism that communicates and shuts off the hydraulic pressure chamber and the hydraulic fluid reservoir side in response to movement in the axial direction, and the piston has one end side facing the hydraulic pressure chamber in the axial direction. A center valve type master cylinder in which a cylindrical retainer is assembled in the recess, and the valve mechanism is located in the center of a space defined by the retainer and the recess,
The valve mechanism is a poppet valve body movable in the axial direction of the cylinder body, a valve seat on the bottom side of the recess, the poppet valve body is separated and seated, and the poppet valve body is moved to the valve seat And one end of the coil spring is supported by the poppet valve body, and the other end is supported by a protrusion that protrudes radially inward from the inner wall of the retainer. In
A center valve type master cylinder characterized in that a fluid passage for communication between the fluid pressure chamber and the hydraulic fluid reservoir side is secured by each of the following configurations.
A. A communication hole that communicates the hydraulic pressure chamber and the hydraulic fluid reservoir side is provided on the radially inner side of the protruding portion that supports the other end of the coil spring.
B. The other end of the coil spring, transverse section there the end of the winding of the coil is traversed in a radial direction of the coil spring is, its cross section is positioned in the axial direction of the end of the coil spring, on which The end face of the poppet valve body on the side supporting one end of the coil spring is completely traversed, and both ends in the radial direction of the transverse part are placed on the projecting part. .
C. When the end face of the poppet valve body facing the hydraulic pressure chamber bends the coil spring and hits the transverse part of the coil spring, a gap remains between the windings of the coil spring. The master cylinder according to claim 1, wherein the coil spring itself limits a maximum movement amount in a direction in which the poppet valve body is separated from the valve seat. When the end surface of the poppet valve body hits the crossing portion of the coil spring, a distance of a distance corresponding to the wire diameter of the coil spring constituting the crossing portion is provided between the end surface of the poppet valve body and the communication hole. The master cylinder of claim 2, wherein The communication hole is only one of the central portions, and when the poppet valve body side is viewed from the hydraulic chamber side through the communication hole, the crossing portion completely crosses the end face of the poppet valve body. Item 1. Master cylinder. Near the opening of the recess of the piston, and on one of the outer circumferences of the retainer that fits into the recess, there are grooves in a plurality of circumferential portions, and on the other side, there are claw portions that fit into the grooves. 2. The master cylinder according to claim 1, wherein the retainer is assembled to the recess of the piston by fitting the claw portion and the groove. The master cylinder according to claim 5, wherein when the groove and the claw portion fit properly, an end surface of the piston located at an opening end of the recess and an end surface of the retainer are flush with each other.

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