JPS6348743B2 - - Google Patents

Abstract

PURPOSE:To obtain a braking power at a fixed enlarged power rate in a large- sized autocycle by using a staged-piston which permits the escape at a connecting port according to a grasping power for controlling a nonreturn valve of a brake hydrostatic pressure generator. CONSTITUTION:When a brake lever is grasped, a manual hydrostatic pressure is transmitted to a brake cylinder via a connecting port 22. By this braking, a calliper 8 is swayed to generate a hydrostatic pressure in a servo hydrostatic pressure generating chamber 16 via a push rod 35, but, at the initial stage of the braking, a nonreturn valve 29 is closed, and the hydrostatic pressure cannot be transmitted. When the grasping power is increased, the manual hydrostatic pressure is increased to shift a staged-piston 17 to the right against the force of a spring, and the nonreturn valve 29 is opened to increase the braking force. When the servo hydrostatic pressure surpasses a certain value, the piston 17 is shifted to the left, and the nonreturn valve is closed to cut the servo work. When a sudden braking is given, a valve body 23 escapes, and a valve seat 28 is closed to transmit the manual high hydrostatic pressure directly.

Description

[Detailed description of the invention] The present invention relates to a servo brake system.

Recently, in large motorcycles, etc., it has become possible to obtain large braking force with a small brake operation force.
Several servo brake systems have been proposed that utilize the torque generated during braking to double the brake fluid pressure, and examples of this type of prior art include, for example, Japanese Patent Laid-Open Nos. 54-30362 and 1983- 30363, JP 54-31867, JP 54-31868
There are those shown in Japanese Patent Application Laid-Open No. 54-33957.

However, in the conventional brake system, after the initial brake fluid pressure is artificially applied, a large braking force is suddenly generated due to the servo action, which has the disadvantage that wheels are likely to lock. In particular, this phenomenon is undesirable because it is caused by a servo action and cannot be controlled by the driver's will.

The present invention solves the above-mentioned drawbacks by automatically controlling the servo action as appropriate depending on the braking force applied by the driver, thereby preventing the servo action from working indefinitely during braking. In addition, it is an object of the present invention to provide a servo brake system that prevents a shortage of hydraulic pressure supplied to a brake cylinder during sudden braking, and that also prevents an unnatural feeling when operating the brake immediately after braking.

The configuration of the present invention for achieving the above object includes: a brake fluid pressure generation source that generates fluid pressure by human operation; a brake device that receives brake fluid pressure and applies braking force to a vehicle; an on-off valve provided in a connection line between the servo brake fluid pressure generation source and the brake device and communicating and blocking the connection line; a stepped piston that is slidably inserted and has a pressure receiving area on the upstream side that is larger than the pressure receiving area on the downstream side and has a communication port that allows the flow of brake fluid; , the communicating port is closed when the stepped piston is pressed downstream in response to hydraulic pressure from the brake hydraulic pressure generation source, and in the closed state, escape movement toward the downstream side is allowed with respect to the stepped piston. The valve mechanism includes a valve mechanism including a valve body that can communicate between the upstream side and the downstream side, and means for opening and closing the on-off valve in accordance with the displacement of the stepped piston.

According to this configuration, when the hydraulic pressure generated by the brake hydraulic pressure generation source increases, the stepped piston is displaced due to the difference in pressure receiving area, and the valve body of the valve mechanism closes the communication port. At the same time, an opening/closing valve provided in a connection line between the servo brake fluid pressure generation source and the brake device is opened, and large hydraulic pressure is transmitted from the servo brake fluid pressure generation source to the brake device to perform a servo action. Then, depending on the magnitude of the hydraulic pressure from the brake fluid pressure source, the stepped piston is displaced by the hydraulic pressure from the servo brake fluid pressure source and closes the on-off valve, so the driver's brake operation force is Therefore, the servo action can be controlled appropriately.

Furthermore, when large hydraulic pressure is generated from the brake hydraulic pressure generation source during sudden braking, the valve body of the valve mechanism provided in the stepped piston escapes to the downstream side and opens the communication port. Large hydraulic pressure from the brake hydraulic pressure source is directly transmitted to the brake device.

The present invention is described below as having a disc brake.
An example in which the present invention is applied to a motorcycle will be described.

In FIG. 1, reference numeral 1 indicates a front fork 2 of a motorcycle connected to the front fork 1 via a support shaft 3.
The front wheels are held in place, and a disc brake 4 is used for braking the front wheels. As shown in FIG. 2, the disc brake 4 includes a brake disc 5 that rotates integrally with the front wheel 2, and a pair of friction pads 6 and 7 arranged to sandwich the disc 5.
A caliper 8 is provided that straddles the outer periphery of the disk 5 and is movable in the axial direction.

This caliper 8 is held via an arm 9 in such a manner that it is allowed to swing slightly around the support shaft 3 (clockwise and counterclockwise swings in FIG. 1). A brake cylinder 10 is provided on one side. When fluid pressure is supplied to the fluid chamber 11 of the brake cylinder 10, one of the friction pads 6 is moved through the piston 12.
is pressed toward one side of the disk 5, and the caliper 8 receiving this reaction force is displaced to the left in FIG.
It is pressed against the other side, thereby performing a braking action.

The front fork 1 is provided with a servo control mechanism 13 located near the caliper 8. This servo control mechanism 13 will be described in detail with reference to FIG. 2. Reference numeral 14 denotes a cylindrical main body, which is fixed to the front fork 1. Inside the main body 14, a valve chamber 15 having a larger diameter on the left side in the figure, and a servo brake fluid pressure generation chamber 16, which will be described later, are defined on the right side of the valve chamber. A stepped piston 17 having a large diameter portion 17a on the left end side and a small diameter portion 17b on the right end side in the figure is slidably inserted into the valve chamber 15. An inlet side (upstream side) liquid chamber 18 is defined on the right side, and an outlet side (downstream side) liquid chamber 19 is defined on the right side.

The liquid chamber 18 has an inlet 20 formed in the main body 14, and the liquid chamber 19 has an outlet 21 formed in the main body 14. They are communicated through a communication port 22 formed in the attached piston 17. The above communication port 22
Inside, there is a valve body 2 which is freely displaceable in the left and right direction as shown in FIG.
3, which is pushed leftward in the figure by a weak spring 24 and comes into contact with a stopper 25 that substantially constitutes a part of the main body 14, and is prevented from being displaced to the left beyond a predetermined value. ing. In addition, the stepped piston 17
is also pressed toward the left side in the figure by the spring 26, and its leftward movement beyond a predetermined value is regulated by the plug body 25. A valve seat 27 is formed on the stepped piston 17 on which the valve body 23 seats and leaves in response to displacement of the stepped piston 17 in the left-right direction in the figure.
The communication port 22 is opened and closed according to the seating and separation of the elements 17 and 27, and in the illustrated state in which both elements 17 and 23 are in contact with the stopper 25, the communication port 22 is opened. be done. The valve body 23 is allowed to move away from the valve seat 27 from the position where it is seated on the valve seat 27 against the force of the spring.

Next, to explain the servo brake fluid pressure generation source for generating the hydraulic pressure for exerting the servo action, the servo brake fluid pressure generation chamber 16 is connected to the outlet through the communication passage 28 formed in the main body 14. A check valve 29 communicated with the side liquid chamber 19 and provided here.
This allows only flow from chamber 19 to chamber 16. This check valve 29 is
A ball-shaped valve body 30 and a valve seat 3 formed on the main body 14
1 and a weak spring 32 that urges the valve body 30 toward the valve seat 31.
A valve rod 33 extends from the stepped piston 17 so as to face the tip end surface of a tapered stopper 17c protruding from the stepped piston 17.

Further, the servo hydraulic pressure generation chamber 16 is defined within the main body 14 by the main body 14 and a servo piston 34 slidably fitted into the main body 14.
A spherical tip 35a of a push rod 35 fits into a hemispherical recess 34a that opens on the right end surface of the piston 34 in the figure, and a base end 35b of the push rod 35 is connected to the main body as shown in FIG. 14
It extends outward and is connected to the front end surface side of the caliper 8. The piston 34 and therefore the push rod 35 are biased toward the right side in FIG. 2 by the return spring 36. A retaining ring 37 restricts the displacement of the piston 34 to the right in FIG. 2 beyond a predetermined value.

In addition, when the caliper 8 is not braking (when the piston 34 is located at the rightward stroke end in FIG. 2), the caliper 8 is restricted from swinging clockwise in FIG. 1 while connected to the push rod 35. . Further, in FIG. 2, reference numeral 38 is a locking member that cooperates with a retaining ring 39 to prevent the push rod 35 from coming off from the piston 34, and 40 is a locking member that prevents the push rod 35 from coming off from the piston 34.
This is an atmosphere release port for releasing the chamber portion formed between the large and small diameter portions of the stepped piston 17 to the atmosphere.

Here, the hydraulic system connection relationship of the servo control mechanism 13 will be explained with reference to FIG. In the figure, reference numeral 41 denotes a master cylinder as a brake fluid pressure generation source, which is fixed to a bar handle 42, and hydraulic pressure is artificially generated by gripping a brake lever 43. This master cylinder 41 is connected by the inlet 20 and the brake pipe 44,
Further, the inlet 21 and the brake cylinder 10 (liquid chamber 11) of the disc brake 4 are connected to the brake pipe 4.
5.

Next, the operation of the above configuration will be explained. When the motorcycle is traveling forward and the brakes are not applied, the servo control mechanism 13 maintains the state shown in FIG. 2. When the brake lever 43 is squeezed to decelerate or stop the running motorcycle, the hydraulic pressure generated in the master cylinder 41 is transferred to the piping 44,
Inflow port 20, liquid chamber 18, communication port 22, liquid chamber 19,
It is transmitted to the brake cylinder 10 of the disc brake 4 through the outlet 21 and the piping 45, thereby causing the pair of friction pads 6 and 8 to move against the brake disc 5.
Braking is performed by pressing from both sides.

When the pair of friction pads 6, 7 press the disk 5, the friction force between the two friction pads 6, 7 and 5 causes the calibar 8 to swing counterclockwise in FIG. 1 about the support shaft 3. be done. This rocking motion of the caliper 8 is transmitted to the servo piston 34 via the push rod 35, which moves to the left in FIG. This generated hydraulic pressure is not transmitted to the outlet side liquid chamber 19 because of the check valve 29 .

As the gripping force of the brake lever 43 is increased, the hydraulic pressure generated in the master cylinder 41 also increases accordingly, and the stepped piston 17 is forced to act on the spring 26 due to the difference in pressure receiving area between the two fluid chambers 18 and 19. It moves to the right in Figure 2 against the resistance, and eventually the valve seat 27
The valve body 23 is seated against. After the valve body 23 is seated on the valve seat 27, the stepped piston 17 and the valve body 23 integrally move to the right in FIG. 30 is pressed to open the check valve 29. When the check valve 29 is opened, the large hydraulic pressure generated in the servo hydraulic pressure generating chamber 16 is transferred to the brake of the disc brake 4 via the outlet side liquid chamber 19, the outlet 21, and the piping 45. The braking force is transmitted to the cylinder 10, further increasing the braking force.

In this way, the braking force increases due to the servo action, but when the fluid pressure in the servo fluid pressure generation chamber 16 and the outlet side fluid chamber 19 exceeds a certain level, the communication port 22 closes. Due to the relationship between the hydraulic pressures acting on both sides of the stepped piston 17 when
The stepped piston 17 moves to the left in FIG. 2, and accordingly, the valve body 23 also moves to the left in FIG. 2 to open the check valve 29 again.
is closed, thereby cutting off the servo action, that is, the transmission of hydraulic pressure from the servo hydraulic pressure generation chamber 16 to the brake cylinder 10 of the disc brake 4.

As is clear from the above explanation, the servo action is automatically cut off depending on the gripping force of the brake lever 43, but when this cut is made, the brake cylinder 10 (liquid chamber 11), that is, the liquid on the outlet side Hydraulic pressure Pw in chamber 19 and master cylinder 41
The relationship with the hydraulic pressure, that is, the hydraulic pressure Pm of the inlet side liquid chamber 18, will be explained. Now, stepped piston 17
If the pressure receiving area of the large diameter portion 17a is A (πr ² when the radius of the large diameter portion 17a is r) and the pressure receiving area of the small diameter portion 17b is a, then the stepped piston 17 is in the state where the communication port 22 is closed. The springs 26 and 24 are stationary.
Ignoring the spring force, the following relationship holds: PmA=Pwa...(1). In other words, when the relationship PW=A/aPm (A/a>1) (2) is established and the brake cylinder hydraulic pressure Pw becomes A/a times the master cylinder hydraulic pressure Pm, the servo action is activated. It is cut. Such characteristics of the present invention are shown in FIG. 3, in which the broken line represents the characteristics without servo utilization, and the solid line represents the characteristics of the present invention.

Here, as can be easily understood from the explanation so far, to simply obtain the above equation (2) without servo action,
The stepped piston 17 has no communication port 22, and the brake fluid on the master cylinder 41 side and the brake fluid on the brake cylinder 10 side are connected to the stepped piston 1.
It is sufficient to completely shut it off at step 7, but in this case, the amount of operation of the brake lever 43 has to be A/a times larger than that without boosting. However, in the present invention, since fluid is replenished from the servo hydraulic pressure generation chamber 16 to the brake cylinder 10 by the servo action, the brake lever 3
The amount of operation in step 9 is so small that it is almost the same as that without the boosting effect.

Now, when braking suddenly, that is, the brake lever 43
If you suddenly grasp and operate with great force,
The stepped piston 17 is rapidly displaced to its downstream side (right side in FIG. 2) to its stroke end, opening the check valve 29. In this state, the valve body 23 is
7, the communication port 22 is closed, and at the beginning of braking, the servo hydraulic pressure generation chamber 1 is closed.
No large hydraulic pressure was generated in 6. However, at this initial stage of braking, a large hydraulic pressure Pm is generated in the master cylinder 41, so
Due to this large hydraulic pressure Pm, the valve body 23 is weakened by the weak spring 2.
4 and is separated from the valve seat 27 against the large hydraulic pressure.
Pm is supplied to the brake cylinder 10 without escaping to the servo hydraulic pressure generation chamber 16.
Of course, after the middle period of braking, the servo hydraulic pressure generation chamber 16
The large hydraulic pressure generated flows into the outlet side liquid chamber 19, and thereafter braking is performed by the same servo action as during normal brake operation.

Immediately after the motorcycle stops due to braking,
The hydraulic pressure in the servo hydraulic pressure generating chamber 16 suddenly decreases. For this reason, the high hydraulic pressure within the brake cylinder 10 attempts to be reversely transmitted into the hydraulic pressure generation chamber 16, but immediately after this stop, the stepped piston 17 rapidly moves to the downstream stroke end and its stopper. Part 17c
The communication path 28 is closed by this. Therefore, immediately after stopping, an extra grip operation (an additional operation amount) of the brake lever 43 to compensate for the reverse transmission is unnecessary.

Although the embodiments have been described above, the present invention is not limited thereto, and includes, for example, the following cases.

In order to generate the mechanical displacement that occurs during braking, that is, the hydraulic pressure in the servo hydraulic pressure generation chamber 16, for example, one of the friction pads 5 and 7 is made freely displaceable in the rotational direction or tangential direction of the brake pad 5, and a caliper is used. 8, and the displacement of the displaceable friction pad may be utilized. Further, instead of using the disc brake 4 itself, for example, the nose dive phenomenon during braking may be used as a mechanical displacement, etc., as appropriate.

It can also be applied to the rear wheel of a motorcycle, and in this case, the displacement of the rear isog arm supporting the rear wheel can be used as the mechanical displacement mentioned above.

It can also be applied to other vehicles other than motorcycles.

The brake device includes, for example, two brake cylinders (in the case of the one in Fig. 2, the caliper 8 is provided with a separate brake cylinder for pressing the friction pad 7), and one brake cylinder is provided on the outflow port side. The fluid chamber 19 may be connected to the other brake cylinder, and the servo fluid pressure generating chamber 16 may be connected to the other brake cylinder via a check valve 29. In short, when servo action is performed,
It is sufficient that the hydraulic pressure in the servo hydraulic pressure generating chamber 16 substantially acts (directly or indirectly) on the outlet side liquid chamber 19.

It can be applied not only to disc brakes but also to drum brakes. In this case, for example, the brake shoe is displaced when it receives frictional force from the drum, and this displacement is transferred to a machine for generating hydraulic pressure for the servo. It can be used as a target displacement.

The servo action may be configured to be performed even when the vehicle is moving backward. In this case, for example, when the caliper 8 swings clockwise in FIG. 1, the servo hydraulic pressure may be generated in response to this swing displacement force.

A check valve 29 for sucking fluid from the brake cylinder 10 into the servo fluid pressure generation chamber 16
is forcibly opened by the stepped piston 17, but an on-off valve that is opened by the stepped piston 17 may be provided separately in parallel with the check valve 29.

As is clear from the above description, the present invention has the following features:
The braking force can be obtained at a constant boost ratio by the appropriate servo action according to the brake operating force, which is very preferable in terms of brake control.

Further, the amount of brake operation (stroke amount) can be small, which is preferable from the standpoint of reducing fatigue associated with brake operation.

Furthermore, even during sudden braking, there is no shortage of hydraulic pressure supplied to the brake cylinder.

Furthermore, there is almost no variation in the amount of brake operation immediately after the vehicle stops, and no discomfort occurs when operating the brakes.

[Brief explanation of drawings]

Fig. 1 is a side view showing an embodiment in which the present invention is applied to the front wheel of a motorcycle, Fig. 2 is a system diagram of the present invention, Fig. 3 is an enlarged sectional view of the main part of Fig. 2, and Fig. 4 is a characteristic diagram of the present invention. 4...Disc brake (brake device), 1
0...Brake cylinder, 16...Brake fluid pressure generation chamber for servo, 17...Stepped piston, 17a
...Large diameter part, 17b...Small diameter part, 22...Communication port, 23...Valve body, 24...Spring (valve mechanism), 2
7...Valve seat, 29...Check valve (on/off valve), 41...
...Mass cylinder (brake fluid pressure generation source).

Claims (1)

[Scope of Claims] 1. A brake fluid pressure generation source that generates fluid pressure by human operation; A brake device that receives brake fluid pressure and applies braking force to a vehicle; A servo brake fluid pressure generation source; provided in a connection path with the brake device, communicating the connection path;
an on-off valve that shuts off, and is slidably inserted in a connection line between the brake fluid pressure generation source and the brake device, and has an upstream pressure-receiving area larger than a downstream pressure-receiving area; a stepped piston having a communication port that allows the flow of brake fluid; and a stepped piston that is provided on the stepped piston and closes the communication port when the stepped piston is pushed downstream in response to hydraulic pressure from the brake fluid pressure generation source. and a valve mechanism including a valve body that allows escape movement toward the downstream side with respect to the stepped piston in the closed state and allows communication between the upstream side and the downstream side, and a displacement of the stepped piston. A servo brake system comprising: means for opening and closing the on-off valve according to the above.