JP3111334B2 - Center valve type hydraulic master cylinder for vehicles - 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 hydraulic master cylinder for hydraulically operating a disc brake of an automobile or a motorcycle, and more particularly to a knockback of a piston disposed inside a caliper body. To a structure that prevents the

[0002]

2. Description of the Related Art In a hydraulic disc brake for a vehicle, a disc rotor has a rotational runout or an axial manufacturing error, and a centrifugal force due to a curve running of a vehicle acts on a pin slide type caliper body. As a result, when the weight is moved in the axial direction of the disk, the piston accommodated in the cylinder hole of the caliper body is pushed back toward the bottom of the cylinder hole more than the normal retreat position, which causes a so-called knockback. There is.

When knock back occurs in this way,
Since the piston stroke is increased at the time of the next braking, the pedal stroke and the lever stroke may be longer than usual, which may cause a problem that the brake feeling is impaired. The indicated technique has been proposed.

According to this technique, one end of an adjusting bolt faces a hydraulic chamber at the bottom of a cylinder hole, and the other end of the bolt projects outside from the bottom wall of the cylinder hole, so that the adjusting bolt and the piston are located between the adjusting bolt and the piston. The coil spring is contracted with a set load smaller than the restoring force of the square seal fitted into the cylinder hole.

[0005]

In such a construction, as the lining of the friction pad wears, the retracted position of the piston moves toward the opening side of the cylinder hole, and the hydraulic pressure chamber is closed. As the length in the cylinder axis direction increases and the set load set on the coil spring gradually weakens,
There is a problem in that the adjusting bolt must be extended to the hydraulic chamber side to adjust the set load frequently.

The present inventor has focused on a hydraulic master cylinder that supplies pressurized hydraulic fluid to a disc brake, and utilizes this hydraulic master cylinder to perform knockback of the piston without performing any artificial adjustment. The purpose is to provide a structure that can be effectively prevented.

[0007]

According to the present invention, a piston is inserted into a cylinder hole formed in a cylinder body to form a boosting chamber between the piston and a bottom wall of the cylinder hole. A supply passage communicating with a reservoir is provided on a bottom wall of the cylinder hole, and a first flange and a second flange that slide through the cylinder hole are formed at front and rear portions of a small diameter shaft portion of the piston. A center valve type hydraulic master cylinder for a vehicle in which a center valve that closes the supply passage by advancing a piston and pressurizes the hydraulic fluid in the pressurizing chamber is attached to a front end of a valve stem protruding from the front end to the pressurizing chamber, The pressurizing chamber is used as a first pressurizing chamber, and a space around the small diameter shaft portion of the piston is used as a second pressurizing chamber, and both pressurizing chambers are connected through a communication passage.
An output port for discharging the pressurized hydraulic fluid to the outside is opened, and the first flange is set so as to be located on the output port when the non-operating piston is located at the retreat limit. Things.

[0008]

According to the above construction, an overload greater than the restoring force of the square seal acts on the piston accommodated in the cylinder hole of the caliper body, and is pushed toward the bottom of the cylinder hole from a predetermined retreat position. In this case, the first flange of the piston located at the opening of the output port hinders recirculation to the second boosting chamber and regulates the retraction of the piston.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

[0010] A disc brake 1 and a hydraulic master cylinder 2, which are disposed separately from each other around a wheel and an engine room (neither is shown), are connected by a brake hose 3, and a brake operation by a driver is performed. The hydraulic fluid pressurized by the hydraulic master cylinder 2 is supplied to the caliper body 6 through the brake hose 3, and the disc brake 1 is hydraulically operated.

The disk brake 1 includes a disk rotor 4 that rotates integrally with the wheels, a caliper bracket 5 fixed to the vehicle body at one side of the disk rotor 4, and a disk axially moving to the bracket 5. The disk rotor 4 is disposed between the pin-sliding type caliper body 6 which is supported so as to be able to move and the action portion 6a and the reaction portion 6b of the body 6.
And a pair of friction pads 7, 7 arranged opposite to each other.

A cup-shaped piston 9 is provided in a cylinder hole 8 provided in the action portion 6a so as to open the disk rotor 4 side.
Is inserted in a liquid-tight manner by a square seal 10 fitted in the cylinder hole 8, and the piston 9 and the bottom wall 6 c of the cylinder hole 8 are inserted.
And a hydraulic chamber 11 is defined. In the bottom wall 6c of the cylinder hole 8, a union hole 12 is formed.
Is connected to one end of a brake hose 3.

The pressurized hydraulic fluid of the hydraulic master cylinder 2 is supplied from the brake hose 3 to the hydraulic chamber 11 and the piston 9
Is pushed out of the cylinder hole 8 toward the opening while the square seal 10 is bent by the pressurized hydraulic fluid. The friction pad 7 on the action portion 6a side is pressed against one side surface of the disk rotor 4 by the piston 9, and the friction pad 7 on the reaction portion 6b side reacts in the direction of the action portion of the caliper body 6 by the reaction. At 6b, the disk rotor 4 is pressed against the other side.

When the above-mentioned braking is released, the piston 9 is returned to the retracted position by the square seal 10 restoring the original shape, and at the same time, the caliper body 6 moves toward the reaction portion and returns to the non-operation state.

The side surface of the disk rotor 4 and the friction pad 7
When the braking gap between the linings 7a is a predetermined amount, the movement of the piston 9 is performed within the deformation amount of the square seal 10. Also, when the lining 7a of the friction pad 7 is worn and the above-mentioned braking gap expands beyond a predetermined amount, the piston 9 is extended to the disk rotor side beyond the deformation amount of the square seal 10, and when the braking is released. Is restored by the restoration amount of the corner seal 10. As a result, the wear of the lining 7a of the piston 9 is adjusted toward the disk rotor, and the braking gap between the disk rotor 4 and the lining 7a is set to a predetermined amount.

The hydraulic master cylinder 2 is of a center valve type in which a supply valve 14 communicating with a supply reservoir 13 is closed by a center valve 16 of a piston 15 and pressurizes hydraulic fluid. The above-described piston 15 is inserted into the provided cylinder hole 18, and the above-mentioned reservoir 13 is integrally formed on the front upper surface of the body 17.

The piston 15 and the bottom wall 17 of the cylinder hole 18
a first pressurizing chamber 19 is defined between the piston 1
The return spring 22 is contracted between the tip of the spring 5 and the spring retainers 20 and 21 disposed on the bottom wall 17a. The piston 15 is repelled by the resilient force of the return spring 22 toward the opening of the cylinder hole 18, and its retreat limit is regulated by a circlip 23 fitted in the opening of the cylinder hole 18. I have.

The first flange 15a and the second flange 1 which slide in the cylinder
5b are integrally formed, and both flanges 15a, 15
The portion between b is a small diameter shaft portion 15c. Small diameter shaft 15
The space on the outer periphery of c serves as a second booster chamber 24,
The pressurizing chamber 19 and the second pressurizing chamber 24 are
Are communicated with each other through a communication passage 25 formed in the upper part of the communication path. A primary cup 26 is provided on the first flange 15a on the front side.
However, a second cup 15 is fitted on the second flange 15b on the rear side, and the first and second pressurizing chambers 19 and 24 are liquid-tightly defined by the two cups 26 and 27. ing.

An output port 28 communicating with the second boosting chamber 24 is formed at the lower portion of the cylinder body 17, and outside the output port 28 formed by a large-diameter female screw hole,
The other end of the brake hose 3 is connected. Further, the inside of the output port 28 is narrowed to a small diameter, so that the pressure of the working fluid inside is easily increased. The first flange 15a of the piston 15 is set so as to be located inside the output port 28 when the piston 15 moves to the retreat limit as described above. Communication is interrupted.

The supply passage 14 includes a valve hole 14a and a horizontal hole 14b formed on the central axis of the cylinder hole 18, and a vertical hole 14c extending from the tip of the horizontal hole 14b to the bottom of the reservoir 13. The working fluid stored in the reservoir 13 can be supplied to the first pressure increasing chamber 19 at any time. Valve hole 14a opening to first pressurizing chamber 19
Is formed to have a larger diameter than the horizontal hole 14b and the vertical hole 14c, and has a front end portion 29a of the valve stem 29 protruding from the front portion of the piston 15 to the first pressurizing chamber 19;
And the above-mentioned center valve 16 mounted on the main body.

A rear end portion 29b of the valve stem 29 is accommodated in a guide hole 15d provided on the central axis of the piston 15 so as to open to the first pressurizing chamber 19.
9b is a spring retainer 21 on the piston 15 side,
Further, the distal end portions 29a are respectively prevented from coming off by the spring retainers 20 on the bottom wall 17a side. Tip 29
A is formed with a flange 29c that slides in the valve hole 14a, and a plurality of liquid holes 30 are formed in the flange 29c. Flange 29c and spring retainer 20
A small-diameter coil spring 31 is contracted with a lower set load than the return spring 22 of the first boosting chamber 19.
The repulsive force acts in the opposite direction.

The valve stem 29 is moved to the rear end portion 29b by the piston 15 resiliently pushed by the return spring 22.
The spring retainer 21 engaging with the cylinder hole 18
And the retraction limit is restricted by the engagement between the tip portion 29a and the spring retainer 20.
The center valve 16 at the distal end portion 29a separates the hydraulic fluid stored in the reservoir 13 from the bottom wall of the valve hole 14a,
Through the supply passage 14 and the liquid passage 30, the liquid can be supplied to the first pressure increasing chamber 19.

Further, the piston 1 is moved by the brake operation.
5 is pushed in the direction of the first pressurizing chamber 19, and when the traction of the spring retainer 21 is released, the valve stem 29
The coil spring 31 is pushed in the direction opposite to the opening of the cylinder hole 18, and the center valve 16 is seated on the bottom wall of the valve hole 14 a to cut off the communication between the reservoir 13 and the first boosting chamber 19.

A push rod 32 pushes the piston 15 of the hydraulic master cylinder 2.
2 is connected to the brake pedal of the driver's seat.

Next, the operation of the present embodiment configured as described above will be described.

In the non-operating hydraulic master cylinder 2, the piston 15 and the valve stem 29 are in the retreat limit positions shown in FIGS.
Means that the communication is cut off by the first flange 15a of the piston 15 closing the output port 28,
The reservoir 13 communicates with the supply passage 14 through a communication hole 30 of the valve stem 29.

When the driver depresses the brake pedal from the above-described state, the piston 15 of the hydraulic master cylinder 2 presses the return spring 22 while pressing the push rod 32 to push the cylinder hole 18 toward the bottom. Go forward to First flange 15 of piston 15
a is formed from the inner opening of the output port 28 to the cylinder hole 18.
Moves to the bottom, and the second pressurizing chamber 24 and the brake hose 3 communicate with each other. Then, the center valve 16 at the tip of the valve stem 29 is seated on the bottom wall of the valve hole 14a, and
Communication between the boosting chamber 19 and the reservoir 13 is cut off.

The hydraulic fluid inside the first pressurizing chamber 19 is gradually pressurized as the piston 15 advances, and the hydraulic fluid in the communication passage 25 and the second pressurizing chamber 24 is also pressurized. The pressurized hydraulic fluid in both the pressurizing chambers 19 and 24 and the inside of the communication passage 25 flows from the output port 28 through the brake hose 3 to the caliper body 6.
And the disc brake 1 is hydraulically operated as described above.

When the brake operation is released,
The piston 15 of the hydraulic master cylinder 2 is pushed back by the return spring 22 through the cylinder hole 18 toward the opening. On the other hand, in the caliper body 6 of the disc brake 1, the piston 9 retreats from the cylinder hole 8 by the square seal 10 which is restored to the original shape, and the hydraulic chamber 11 is reduced. The hydraulic fluid flows back to the second pressurizing chamber 24 through the brake hose 3.

Next, in the hydraulic master cylinder 2, the spring retainer 21 on the piston 15 side
9 comes into contact with the rear end portion 29 b, and the stem 29 is pulled toward the opening of the cylinder hole 18 against the elastic force of the coil spring 31. The center valve 16 is separated from the bottom wall of the valve hole 14 a by the retreat of the valve stem 29, and the hydraulic fluid flowing to the reservoir 13 before the valve 16 shuts off the supply path 14 is returned to the first pressure increasing chamber 19. Go.

The piston 9 of the disc brake 1
Reaches a predetermined retreat position, and the piston 15 of the hydraulic master cylinder 2 is retracted by the circlip 23 in accordance with the return of the appropriate hydraulic fluid from the hydraulic chamber 11 to the second boosting chamber 24. And the first flange 15a is located inside the output port 28 to cut off the communication between the second pressurizing chamber 24 and the brake hose 3.

The disk rotor 4 has a rotational runout or an axial manufacturing error, or a centrifugal force due to the curve running of the vehicle acts on the caliper body 6, causing a weight movement in the disk axial direction and causing the piston 9 to move. When a pushing force greater than the restoring force of the square seal 10 is applied, the piston 9
The first flange 15 a of the piston 15 located inside the output port 28 of the hydraulic pressure master cylinder 2 allows the flow from the brake hose 3 to the second pressure increasing chamber 24 even if the In order to cut off, the piston 9 is prevented from retreating.

Further, when the friction pad 7 changes its retreat position toward the disk rotor 4 due to the wear of the lining 7a, the amount of hydraulic fluid in the hydraulic chamber 11 is increased by an enlarged area. Only by this, the first flange 15a of the piston 15 cuts the recirculation of a predetermined amount or more from the hydraulic pressure chamber 11 and the brake hose 3 to the second pressurizing chamber 24, and effectively prevents the piston 9 from retreating.

The communication passage connecting the two boosting chambers may be routed outside the cylinder body by piping. In the hydraulic master cylinder of the present invention, it is not always necessary to completely close the output port. For example, even if the first flange is made smaller in diameter than the cylinder hole, or the first flange is shifted from the output port in the cylinder axis direction, even if there is a slight gap between the first flange and the output port, the first flange is not moved from the brake hose. (2) Since the recirculation to the boosting chamber is restricted over time, knockback of the piston is not easily permitted.

[0035]

As described above, in the center valve type hydraulic master cylinder of the present invention, the first pressure rising chamber is formed between the piston and the bottom wall of the cylinder hole, and the first flange and the second flange of the piston are formed. An output port for discharging the pressurized hydraulic fluid to the outside to the second pressurizing chamber by forming a space around the outer periphery of the small-diameter shaft portion between the flange and the flange as a second pressurizing chamber, connecting the two pressurizing chambers through a communication passage. And the first flange is set to be located on the output port when the piston is located at the retreat limit, so that knockback of the piston disposed on the disc brake is effectively prevented. In particular, even when the lining of the friction pad is worn, it does not need to be artificially adjusted, so that the function is excellent. Further, also in terms of structure, the communication passage connecting the first and second pressurizing chambers is formed, and a simple structure in which the communication passage is located on the first flange of the piston and the output port is sufficient, and it is inexpensive and easy. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a connection diagram of a hydraulic master cylinder and a disc brake showing one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the hydraulic master cylinder shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Disc brake 2 ... Hydraulic master cylinder 3 ... Brake hose connecting disc brake 1 and hydraulic master cylinder 2 4 ... Disc rotor 6 ... Caliper body 6c ... Bottom wall of hydraulic chamber 11 7 ... Friction pad 7a ... Lining 8 ... Cylinder hole of the disc brake 1 9 ... Piston of the disc brake 1 10 ... Square seal 11 ... Hydraulic chamber 12 ... Union hole 13 ... Reservoir 14 ... Supply path connecting the first pressure increasing chamber 19 and the reservoir 13 14a ... Valve hole 15: Piston of hydraulic master cylinder 2 15a: First flange of piston 15 15b: Second flange of piston 15 15c: Small diameter shaft portion of piston 15 15d: Guide hole 16: Center valve 17: Cylinder of hydraulic master cylinder 2 Body 17a: bottom wall of cylinder hole 18 ... hydraulic master cylinder 2 Cylinder hole 19: first pressurizing chamber 20, 21 ... spring retainer 22 ... return spring 23 ... circlip 25 ... communication path for communicating the first pressurizing chamber 19 and second pressurizing chamber 24 26 ... primary cup 27 ... secondary cup 28 … Output port 29… Valve stem 32… Push rod

Claims (1)

(57) [Claims] 1. A piston is inserted into a cylinder hole formed in a cylinder body to define a boosting chamber between the piston and a bottom wall of the cylinder hole, and the bottom wall of the cylinder hole communicates with a reservoir. A first flange and a second flange that slide in a cylinder hole at front and rear portions of a small diameter shaft portion of the piston, and a distal end of a valve stem protruding from the distal end of the piston to the pressurizing chamber. In a center valve type hydraulic master cylinder for a vehicle equipped with a center valve that closes the supply path by advancing a piston and pressurizes hydraulic fluid in a pressurizing chamber, the pressurizing chamber is formed as a first pressurizing chamber, A space around the small-diameter shaft portion of the piston is used as a second pressurizing chamber, the two pressurizing chambers are connected by a communication passage, and an output port for discharging the pressurized hydraulic fluid to the outside is opened in the second pressurizing chamber. , When not operating When Ston is in the retreat limit,
A center valve type hydraulic master cylinder for a vehicle, wherein the first flange is set to be located on the output port.