JP2001010477A - Master cylinder internal hydraulic pressure detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To omit the space for mounting a hydraulic sensor by mounting a displacement sensor for detecting the axial displacement of an operating member on the operating member for generating a hydraulic pressure in a master cylinder, and detecting the hydraulic pressure generated in the master cylinder from the displacement of the operating member. SOLUTION: A push rod 3 is moved forward while deflecting a disc spring 25 and return springs 22, 23. To detect the brake hydraulic pressure by a differential transformer 24, the voltage in the differential transformer 24 is detected according to the stroke of the push rod 3, and the brake hydraulic pressure conformed to the stroke of the push rod 3 is determined from the relation between the predetermined voltage of the differential transformer and the brake hydraulic pressure. Since the hydraulic pressure in a master cylinder can be detected by detecting the displacement of the push rod 3, the space for mounting a hydraulic sensor can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder hydraulic pressure detecting device capable of detecting a change in hydraulic pressure in a master cylinder without using a pressure sensor. An operation member (push rod) for generating pressure is provided with a displacement sensor capable of detecting a displacement amount of an operation member (hereinafter referred to as a push rod), and a displacement sensor in the master cylinder capable of detecting a change in hydraulic pressure in the master cylinder. The present invention relates to a hydraulic pressure detection device.

[0002]

2. Description of the Related Art Conventionally, a vehicle brake device that obtains a braking force by using a brake fluid pressure is well known, and such a device includes a brake circuit in a brake circuit for performing various types of brake control and evaluation. A fluid pressure sensor that detects fluid pressure is used. For example, Japanese Patent Application Laid-Open No. HEI 10-181575 discloses a system in which a hydraulic pressure sensor is provided in each of two brake pipe lines.

[0003]

However, when a hydraulic pressure sensor is installed in the piping, the number of parts on the piping requiring sealing means increases, the cost increases, and a space for mounting the hydraulic pressure sensor is required. Become. In addition, it is necessary to secure a considerable space for mounting the hydraulic pressure sensor in a narrow vehicle (especially, in an engine room), and there is a problem that the mountability of the hydraulic pressure sensor is poor. Therefore, the present invention provides a master cylinder which can largely eliminate a mounting space for mounting a hydraulic pressure sensor by attaching a hydraulic pressure detecting means capable of detecting a hydraulic pressure generated in the master cylinder to a push rod as an operating member of the master cylinder. It is an object of the present invention to provide an in-cylinder hydraulic pressure detecting device and to solve the above problem.

[0004]

Means for Solving the Problems To achieve the above object, the technical solution adopted by the present invention is to provide an operating member for generating a hydraulic pressure in a master cylinder with an axial displacement of the operating member. A hydraulic pressure detecting device in the master cylinder, which is provided with a displacement sensor for detecting, and detects a hydraulic pressure generated in the master cylinder based on a displacement amount of the operating member. A hydraulic pressure detecting device in the master cylinder, wherein an elastic body that increases the displacement of the operating member is disposed between the operating member that presses the hydraulic pressure generating piston of the master cylinder. A master cylinder hydraulic pressure detecting device in which an elastic body to be enlarged is disposed, wherein the displacement sensor is a differential transformer. A master cylinder hydraulic pressure detecting device, wherein the displacement sensor is a capacitor voltage converting device that detects an axial displacement of an operating member, wherein the capacitor voltage converting device is a master cylinder hydraulic pressure detecting device. Is a hydraulic pressure detecting device in the master cylinder, which is provided in the axial direction of the operating member and is provided with electrodes on both sides of the insulating elastic member.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the master cylinder hydraulic pressure detecting device according to the first embodiment of the present invention. In the figure,
1 is a rod connected to a brake pedal, 2 is a brake booster, 3 is a push rod as a master cylinder operating member provided in the brake booster 2, 4 is a master cylinder as brake fluid pressure generating means described later,
When the brake pedal is depressed, a hydraulic pressure is generated in the master cylinder 4 via the rod 1, the brake booster 2, and the push rod 3, and the hydraulic pressure can be supplied to a brake device (not shown). Since the structure of the brake booster 2 is the same as that of the conventional brake booster, a description of its operation and structure will be omitted.

In FIG. 1, a master cylinder body 11
A primary piston 12 and a secondary piston 13 are disposed in the inside, and a first hydraulic chamber 14 is provided between the primary piston 12 and the secondary piston 13.
However, a second hydraulic chamber 15 is formed between the secondary piston 13 and the main body. The first hydraulic chamber 14 has a first inlet port 16 communicating with the reservoir 10 and a first outlet port 17 connected to a brake pipe, and the first inlet port 16 and the first outlet port 17 are not operated by a brake. In some cases, the communication is performed as shown in the drawing, and when the brake is operated, the communication is not performed by the seal member 12 a provided on the primary piston 12. A liquid chamber 18 is formed around the primary piston 12 to allow the inflow of brake fluid when the brake is operated.

The second hydraulic chamber 15 has a second inlet port 19 communicating with the reservoir 10 and a second outlet port 20 connected to the brake pipe. The second inlet port 19 and the second outlet port 20 are connected to each other. When the brake is not operated, the communication is performed as shown in the figure. When the brake is operated, the seal is provided by the seal member 13a provided on the secondary piston 13. A liquid chamber 21 is formed around the secondary piston 13 to allow the flow of brake fluid when the brake is operated. First outlet port 17, second
Two systems of brake pipes are connected to the outlet port 20, and the primary piston 12 and the secondary piston 13 are maintained in the illustrated state by the urging forces of the first return spring 22 and the second return spring 23 when not operating. The structure and operation of this master cylinder are the same as those of the conventional master cylinder.

The primary piston 12 has a tip 3a of a push rod 3 projecting from the brake booster 2.
Are arranged to face each other, and a predetermined gap S is formed between the push rod tip 3a and the primary piston 12 as shown in the figure. This gap S is formed as a distance where the tip 3a of the push rod and the primary piston 12 do not come into contact with each other during normal brake operation. A displacement sensor 24 composed of a conventionally known differential transformer or the like is attached to the periphery of the push rod 3 on the side of the brake booster 2. Further, a flange 3c is formed on the push rod 3, and the flange 3c is formed. A plurality of disc springs 25 are arranged between the main piston 12 and the primary piston 12 as shown in the figure. The disc spring 25 is provided for the purpose of improving the sensitivity of the displacement sensor (differential transformer) 24.

Here, the configuration of the differential transformer that constitutes the displacement sensor 24 will be described. This transformer is a pusher corresponding to the connection between the primary coil 24a, the secondary coil 24b, the primary coil, and the secondary coil. The step portion 3b is formed on the rod side, and the displacement of the push rod 3 can be detected by detecting a change in the AC voltage generated when the step portion 3b moves to the secondary coil 24b side. Therefore, the sensitivity increases as the displacement amount increases (the movement amount of the step portion 3b increases). A conventionally known differential transformer can be used.

By the way, the above-mentioned disc spring load is applied to the inside of the master cylinder 4 in order to secure the invalid stroke a (described later) in the master cylinder portion shown in the detailed view of the portion A in FIG. The load is set to be lower than the loads of the return springs 22 and 23 for urging the primary piston 12 and the secondary piston 13. The invalid stroke is a stroke until the seal members 12a and 13a provided around the primary piston 12 and the secondary piston 13 close the ports 16 and 19, as shown in the partial view of FIG. But is eventually part of the brake pedal play.

Next, the operation of the master cylinder will be described. When a brake pedal (not shown) is depressed, the brake booster is activated, and the push rod 3 advances by an invalid stroke a while bending the disc spring 25 and the return springs 22 and 23, and the first inlet port 16 and the first outlet port 17 Are disconnected from each other by a seal member 12a provided on the primary piston 12, and the first hydraulic chamber 14 is shut off from the reservoir. At the same time, the second inlet port 19 and the second outlet port 20 are connected to the secondary piston 1.
The second hydraulic chamber 15 is shut off from the reservoir 10 by the seal member 13 a provided in the third valve 3. Thereafter, the push rod 3 moves forward while bending the disc spring 25 and the return springs 22 and 23 to move the first and second hydraulic chambers 1.
When hydraulic pressure is generated in the push rods 4 and 15, and the push rod 3 moves forward, the pistons 12 and 13 move against the urging forces of the return springs 22 and 23, and the first and second hydraulic pressures in the master cylinder are moved. A predetermined hydraulic pressure is generated in the chambers 14, 15, and the brake device is operated.

FIG. 2 shows the relationship between the stroke of the push rod 3 and the brake fluid pressure at this time. In the figure, the point (a) is a hydraulic pressure generating point at which the actual brake hydraulic pressure is generated after the end of the invalid stroke.
This is caused by moving forward while bending the second and the second 23. In this embodiment, the push rod is advanced while bending the disc spring 25 and the return springs 22 and 23. Therefore, in order to obtain a normal brake fluid pressure, the push rod is advanced as shown in FIG. As shown, the stroke L of the push rod increases, and as a result, the sensitivity of the differential transformer can be improved. Here, a method of detecting the brake fluid pressure by the differential transformer 24 will be described with reference to FIG. 3. In FIG. 3A, the voltage V in the differential transformer is detected corresponding to the stroke of the push rod. Then, in FIG. 3B, the brake fluid pressure corresponding to the stroke of the push rod can be determined from the predetermined relationship between the voltage V of the differential transformer and the brake fluid pressure. The movement of the primary piston 12 and the secondary piston 13 causes the brake fluid from the reservoir to flow into and out of the fluid chambers 18 and 21 formed around each piston. As described above, in the present embodiment, since the displacement of the push rod 3 can be detected and the hydraulic pressure in the master cylinder can be detected, the hydraulic pressure sensor is mounted as in the case where the hydraulic pressure sensor is disposed in a conventional pipe. Space is not required, and space can be saved.

Next, a master cylinder hydraulic pressure detecting device according to a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a push rod is separated into two members 3A and 3B instead of the disc spring of the first embodiment, and a spring 25A is arranged between the push rods. The step portion is also configured as a spring seat. By employing this configuration, the outer diameter can be reduced as compared with the configuration in which the disc spring is arranged around the push rod. Note that the operation of the second embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

Next, a master cylinder hydraulic pressure detecting device according to a third embodiment will be described with reference to FIG. Note that the same members as those in FIG. 1 are described using the same reference numerals. The third embodiment is different from the first embodiment in that a CV conversion circuit is used as a unit for detecting the displacement of the push rod 3, and therefore, the description will be focused on its characteristic points.
In FIG. 5, the push rod 3 is composed of two members 3A and 3B as in the second embodiment, and a CV conversion circuit for converting a change in the capacitance of the capacitor into a voltage is provided between the two members. . This CV conversion circuit will be described.
The push rod 3 is cut at an appropriate position, electrodes 31 and 32 are attached to respective cut portions, and an insulator 33 made of an elastic member is disposed between the electrodes 31 and 32. Further, the push rod 3A is attached in a state where its tip is in contact with the primary piston 12 as shown in the figure.

The operation of the third embodiment will be described. When an axial force acts on the push rod 3B, the insulator 33 made of an elastic member is compressed, the distance between the electrodes 31, 32 is reduced, and the capacitance of the capacitor is reduced. And this capacitance change is taken out as a voltage change. Here, a method of detecting the brake fluid pressure by the CV conversion circuit will be described with reference to FIG.
The distance between 1 and 32 decreases, and the capacitance of the capacitor changes.
In FIG. 6A, the change in the capacitance of the capacitor corresponding to the stroke of the push rod at this time is obtained.
In (b), a voltage V corresponding to the capacitor capacity is obtained from the relationship between the predetermined capacitor capacity and the voltage V. Further, in FIG.
And the brake fluid pressure P, the brake fluid pressure P corresponding to the voltage V is obtained. As described above, in the present embodiment, the displacement of the push rod 3 is detected by the CV conversion circuit, and the hydraulic pressure in the master cylinder can be detected. Space for mounting a hydraulic pressure sensor is not required, and space can be saved. Further, in this embodiment, a disc spring is not required, the configuration is simplified, and the mounting space can be further reduced as compared with the hydraulic pressure sensor of the first embodiment.

[0016]

As described in detail above, according to the present invention,
Since the displacement of the push rod 3 of the master cylinder is measured and the brake fluid pressure can be detected based on the displacement, the size of the device can be reduced. In addition, it is not necessary to install a hydraulic pressure sensor in the pipe, and the number of parts on the pipe that require a tight means is reduced, so that excellent effects such as cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a brake fluid pressure generation unit according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a stroke of a push rod and a brake fluid pressure in the first embodiment.

FIG. 3 is an explanatory diagram for obtaining a brake fluid pressure from a stroke of a push rod in the first embodiment.

FIG. 4 is an enlarged sectional view of a push rod portion according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a brake fluid pressure generation unit according to a third embodiment of the present invention.

FIG. 6 is an explanatory diagram for obtaining a stroke of a push rod and a brake fluid pressure in a third embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rod 2 brake booster 3 push rod 3b step 3c flange 4 master cylinder 11 master cylinder body 12 primary piston 13 secondary piston 14 first hydraulic chamber 15 second hydraulic chamber 16 first inlet port 17 first outlet port 18 Liquid chamber 19 Second inlet port 20 Second outlet port 21 Liquid chamber 22 First return spring 23 Second return spring 24 Displacement sensor 24a Primary coil 24b Secondary coil 25 Disc spring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Kunimi 195-1 Nihonbashi Koamicho, Chuo-ku, Tokyo Inside Akebono Brake Industry Co., Ltd. (72) Inventor Kazuo Murata 1-1-1 Daihatsucho, Ikeda-shi, Osaka Daihatsu Industry Co., Ltd. (72) Katsuyuki Nakagawa 1-1, Daihatsu-cho, Ikeda-shi, Osaka Daihatsu Industry Co., Ltd. (72) Hiroo Yakushijin 1-1, Daihatsu-cho, Ikeda-shi, Osaka Daihatsu Industrial Co., Ltd. F term (reference) 3D047 BB41 CC07 FF15 FF22 HH10 HH13

Claims (6)

[Claims] An operation member for generating a hydraulic pressure in a master cylinder is provided with a displacement sensor for detecting an axial displacement of the operation member, and a hydraulic pressure generated in the master cylinder based on a displacement amount of the operation member. A master cylinder hydraulic pressure detecting device for detecting. 2. The master cylinder hydraulic pressure detecting device according to claim 1, wherein an elastic body for increasing the displacement of the operating member is arranged between the hydraulic pressure generating piston of the master cylinder and the operating member. 3. The master cylinder hydraulic pressure detecting device according to claim 1, wherein an elastic member for increasing the displacement of the operating member is disposed in the operating member for pressing the hydraulic pressure generating piston of the master cylinder. . 4. The master cylinder hydraulic pressure detecting device according to claim 1, wherein said displacement sensor is a differential transformer. 5. The master cylinder hydraulic pressure detecting device according to claim 1, wherein said displacement sensor is a capacitor voltage converting means for detecting an axial displacement of the operating member. 6. The hydraulic pressure in a master cylinder according to claim 5, wherein said condenser voltage converting means is provided in the axial direction of the operating member, and is provided with electrodes on both sides of the insulating elastic member. Detection device.