JPS6383419A - Disk brake with booster - Google Patents

Abstract

PURPOSE:To increase braking force without using a vacuum servo by mounting both a differential piston functioning as a hydraulic booster and a limiting valve used to supply additional liquid and circulate it. CONSTITUTION:A staged differential piston 25 is inserted in a staged bore 27 to provide liquid tightness between both a primary input chamber 30 on which liquid pressure works and a primary output chamber 30 which is communicated with a cylinder 6. A valve seat 39, a limiting valve body 42 which has a valve head part 42a and shuts off liquid communication between a secondary input chamber 40 and a secondary output chamber 41 at the valve seating time, and a spring 43 are mounted inside a bore 38 which communicates a pipe passage 37 reaching the cylinder 6 with the primary input chamber 30. Air mixed in working liquid in the pipe passages 35 and 37 is discharged via the cylinder 6. Without a pressure amplifying source, input liquid pressure can be increased to increase in braking force of a brake and the brake can poccess high response and high effectiveness in cost and space.

Description

[Detailed Description of the Invention] [Industrial Application Field] As a means for increasing the braking force in a specific disc brake, it is possible to increase the braking force by increasing the friction coefficient of the friction pad, the effective braking radius of the disc rotor (disk), or the hydraulic pressure. It is effective to increase the
It is customary to use a vacuum servo as the actuator.

This invention relates to a disc brake in which a hydraulic pressure booster is built into the caliper body, which eliminates the need for a special booster such as a vacuum servo.

[Conventional technology and its problems]

The design space C for the brake, which is stored inside the wheel around the vehicle's suspension, is an annular front space surrounded by the inner diameter of the wheel and the outer diameter of the hub.

By the way, disc brakes installed in such spaces are often specified by the effective braking radius of the disc and the friction coefficient of the friction pad.

When it is required to increase the output (braking force), the cylinder area must be increased or the input hydraulic pressure must be increased.

On the other hand, when increasing the cylinder area, there is a method of increasing the diameter of a single cylinder, but since this method is limited by the annular space, it requires arranging multiple cylinders in the circumferential direction. As a result, a problem arises in which the amount of fluid in the master cylinder is insufficient.

Further, when increasing the input hydraulic pressure, if the pedal depression force of the master cylinder is specified and considered, the two-pedal ratio will be increased, but there are restrictions on the pedal stroke. For this reason, a vacuum servo or the like is required, which not only increases cost but also requires additional space for assembly.

This invention is a disc brake developed with the aim of solving these problems.

Means for Solving Problem C] In order to solve the above problems, the present invention provides a caliper body with a differential piston as a hydraulic pressure booster and a limiting valve for replenishing the fluid volume and circulating the fluid. It is something.

The differential piston uses the large diameter end of the pressure receiving area A1 as the input hydraulic pressure P, and the small diameter end of the pressure receiving area A2 as the output hydraulic pressure P'.
The input chambers are exposed to each other and are biased toward the input chamber by a first spring.

On the other hand, the limiting valve receives the input hydraulic pressure in the valve closing direction and the output hydraulic pressure and the second spring force in the valve opening direction, and when the input hydraulic pressure reaches a predetermined value, the input/output chamber of the differential piston is closed. The communication path that was made open is now cut off.

In addition, the set load of the first spring is set to be approximately equal to the value obtained by the formula P (A, -A2) when the limiting valve is closed, and the differential piston is applied immediately after the limiting valve closes the communication path. A width-enhancing action is now taking place.

In this way, even if the diameter of the cylinder that applies hydraulic pressure to the brake piston is determined based on the discharge volume of the master cylinder, the limited hydraulic pressure that can be obtained by specifying the pedal depression force can be freely controlled by the operation of the differential piston. The hydraulic pressure can be increased, and braking force can be increased without using a vacuum servo or the like.

〔Example〕

Hereinafter, the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an enlarged sectional view of a hydraulic booster portion, which characterizes the present invention, taken along line II in FIG. 2. Moreover, FIGS. 2 to 4 show a floating type disc brake with a parking brake to which the present invention is applied.

The floating type disc brake is provided with an actuator including a brake piston 3 (FIG. 3) for suppressing the friction material 1 on one side of the caliper body 2 as means for pressing the disc D from both sides with the friction materials 1 and 1'. , in order to transmit the pressing force from the caliper to the friction material 1' using reaction force, and to move the caliper body in the disk axial direction in accordance with wear and tear of the friction material, on both the rotation side and the rotation side of the disk. It is common to provide the slide portion 4 on only one side (sometimes only on one side).

On the other hand, many parking brakes use a friction material for service brakes to generate braking force, and the brake shown in this example is no exception. The inner bottom of the brake is pressed by a drive nut (described later) supported by a cylinder or bar 5, and the structure is slightly different from that of a general built-in type brake. Therefore, before describing the main parts of the present invention, these points will be further explained.

As shown in FIG. 3, the caliper body 2 is provided with a cylinder 6 that houses the piston 3, and within the cylinder is a well-known piston seal that has both a liquid sealing function for the cylinder chamber and a piston glide tract function. 7 is inserted into the square groove. Further, the caliper body is provided with a hydraulic pressure introduction hole 8 (see FIGS. 1 and 2) communicating with the liquid seal chamber of the cylinder 6. 9 is a retractable dustproof boot that seals the entrance of the cylinder 6.

As shown in FIG. 3, the parking brake has a cylinder cover 5 bolted to the caliper body with a protruding cylindrical boss portion 1° facing into the cavity of the cup-shaped piston 3. A flat part 1 having a drive nut 11 formed on the outer periphery of the drive nut 11 whose tip abuts against the inner bottom of the piston 3.
Roll pin 1 supported on the inner surface of boss portion 10 with respect to 2
The cylinder cover 5 is inserted so that it can be moved in the axial direction of the disk while being prevented from rotating by bringing the cylinder cover 5 into contact with the cylinder cover 5.
In this case, the reaction force receiver that is fixed to the cover has a shoulder part 14, and the threaded part on the tip side passes through the drive screw 15 that is screwed into the drive nut 11 by sealing it with an O-ring 16. The input lever 18 is detachably attached to the end of the screw 15 protruding from the cover 5 via a serration groove 17. This parking brake
Connect the inner cable end of the wire cable (not shown) extending from the brake lever to the outer end of the input lever.
The outer cable ends are connected to the cable brackets 19 shown in FIGS. 2 and 4, respectively, and are activated by input from the wire cable. That is, when the lever 18 is pulled by the wire cable and rotates in the direction of the arrow in FIG. A pressing force is generated. In addition, lever 1 due to wear of the friction material
The increase in the rotation angle of 8 is absorbed by changing the attachment of the lever 18 to the drive screw 15.

As shown in FIG. 4, the slide portion 4 of the caliper has a pin hole 21 bored at the tip of the arm of the torque member 20, and a slide pin 23 fixed to the caliper body with a bolt 22 is inserted into this hole. In some cases, a metal sleeve or a rubber bushing may be interposed between the pin hole 21 and the slide pin 23. 24 is the dustproof pin hole 21,
These are retractable pin boots designed for waterproofing.

Next, returning to FIG. 1, the main parts of the present invention will be explained in detail.

As shown in the figure, a differential piston 25 and a limiting valve 26 are provided between the hydraulic pressure introduction hole 8 and the cylinder 6.

The differential piston 25 is a stepped piston having a large diameter at one end and a small diameter at the other end, and is inserted into the stepped bore 27. Additionally, O-rings 28 and 29 are attached to the large diameter part and the small diameter part of this piston, respectively, and input hydraulic pressure is applied to the large diameter end with a cross-sectional area A1.%1 Manual blade chamber 0 and the small diameter end with a cross-sectional area A2 A liquid seal is formed between the first output chambers 31 that apply output hydraulic pressure to the first output chamber 31 .

Further, the open end side of the first output chamber 31 is liquid-sealed by holding the plug 33 fitted with the O-ring 32 with a C-shaped retaining ring 34. be communicated with. 36 is a return spring of the differential piston.

On the other hand, the limiting valve 26 has a valve seat 39 in a bore 38 that communicates the first output chamber 31 with a conduit 37 leading to the cylinder 6, and a valve seat 39 extending from the second blade chamber 40 to the second output chamber 41. Insert the valve body 42 and the limiting spring 43 and connect the open end of the second blade chamber 40 with the plug 45 fitted with the O-ring 44.
The open end of the plug 1 is sealed with an O-ring 46 and a plug 48 fitted with a cup seal 47.

49 is a C-shaped retaining ring that prevents the plug 44 from being removed; 50 is a C-shaped ring that prevents the plug 48 from being removed; 51 is a retainer that holds the valve seat 39; 52 is a retainer that holds the cup seal 47 and also serves as a spring receiver. It is.

The valve body 42 has a valve head 421 facing the second output chamber 41.
The small diameter end side of the cross-sectional area 3 has its outer periphery sealed by a cup seal 47 and is slidably received by a plug 48. In addition, a bore 3 is located in the middle of this valve body 42.
A hexagonal stem guide 42b through which liquid can flow is formed and partially contacts the inner surface of the intermediate small diameter portion of the valve 8. A spring 43 is compressed between this guide and the retainer 52, and its urging force causes the valve body 42 to move. It is held in the valve open position shown in the figure, which is separated from the valve seat 39.

The liquid chambers of the bores 27 and 38 are connected to the cylinder 6 placed above during use via pipes 35 and 37, and
Since the cylinder 6 is connected to a conduit 54 which is closed to a bleed valve 53 shown in FIG. 2, all air mixed in the working fluid can be discharged from the bleed valve 52.

The operating principle of the above-mentioned hydraulic booster section will be described below.

The brake fluid supplied from the master cylinder (not shown) to the hydraulic pressure introduction hole 8 is transferred from the first blade chamber 3o to the second output chamber 41.
and reaches the C cylinder 6 via a conduit 37. When the supply liquid pressure increases, a force p-a is generated to the right, where P is the supply liquid pressure acting on the small cross-sectional area 1 of the valve body 42.

In response to this, the spring 43 urges the main body 42 to the left with a force of F, but when the equilibrium state of F=p-a (1) is reached, the valve The main body 42 compresses the spring 43 and
The valve head 421 moves to the right and comes into contact with the valve seat 39, cutting off liquid communication from the second output chamber 41 to the second output chamber 41. Therefore, from then on, as shown in B and C in FIG. 5, the output hydraulic pressure increases less through the limiting valve.

However, when the limiting valve 26 closes, the first valve facing the small diameter end of the differential piston 25
The hydraulic pressure P' in the output chamber 31 is set equal to the value obtained by the equation (2), and the cutoff pressure P of the limiting valve 26 is expressed by the equation (1) above. (2)
If the working pressure P' of the differential piston 25 shown by the formula is matched, the pressure increase pattern in the first and second output chambers becomes the state shown in FIG. 6, and the hydraulic pressure increased in the brake piston 3 is loaded. Furthermore, when the brake is released, the limiting valve 26 opens and the brake fluid flows back to the master cylinder, and the differential piston 25 returns to its original position by the force of the spring 36.

The set load f of the spring 36 is −(A, −A
2) It may be slightly larger than 2), but the valve body 4
The area of each part of 2 and the force of the spring 43 are determined by the force increase due to the compression of the spring 43, where b is the cross-sectional area of the mouth of the valve seat 39, in order to prevent the limiting valve 26 from opening during braking due to an increase in hydraulic pressure. When ignoring Pmax"≧P'maX (""-")10F, it is decided to maintain the power relationship.

〔effect〕

According to the invention described above, the effects listed below can be obtained.

(1) Due to the operation of the differential piston,
Since the limited input hydraulic pressure can be increased to any desired hydraulic pressure without using a special boosting pressure source such as vacuum pressure, the cylinder area and master cylinder cover are limited and C also increases braking force. It can be done.

(The operation of the 211J Mitsuting Valve automatically replenishes the fluid volume in the output hydraulic pressure sealing part, which expands in volume as the friction material wears, so the width is always constant regardless of the progress of friction material wear.) A width ratio can be obtained.Furthermore, since the brake fluid is returned by opening the valve or passing it through a fitting valve, sufficient responsiveness in releasing the brake can be ensured.

(Until the 311J Mitsuting Valve closes, the input fluid pressure flows directly to the cylinder, consuming the fluid amount equivalent to the minimum necessary cylinder diameter, and the AI/A2
Since the required wave meter is doubled, there is no wastage of fluid volume and does not lead to an increase in pedal stroke.

(4) Since a booster such as a vacuum servo is not required, it is advantageous in terms of cost and installation space.

(5) Since the input hydraulic pressure section and the output hydraulic pressure section are in communication while the IJ fitting valve is open, air mixed in the brake fluid can be easily discharged.

The present invention can also be applied to a general floating type disc brake without a parking brake, a piston opposed type disc brake in which a pair of friction brakes is pressed by a brake piston, and the like.

[Brief explanation of the drawing]

FIG. 1 shows the characteristic parts of the disc brake of the present invention in a second
2 is a front view showing an example of a disc brake to which the present invention is applied, and FIG. 3 is a sectional view taken along line [-11I in FIG. Figure 4 is a side view of the slide section broken away. FIG. 5 is a diagram showing a pattern of increase in hydraulic pressure via the limiting valve, and FIG. 6 is a diagram showing a pattern of increase in hydraulic pressure on the output chamber side of the differential piston. 1.1'...Friction material, 2...Caliper body, 3...
・Brake piston, 4...Slide part, 5...Cylinder force/N#, 6...Cylinder, 7...Piston seal, 8...Hydraulic pressure introduction hole, 11...Drive nut, 15... Drive screw, 18... Input lever, 2o... Torque member, 25... Differential piston, 26... Limiting valve, 30... First power room, 31... No. 1 output room, 3
5.37...Pipe line, 36.43...Spring, 3
9...Valve seat, 40...Second human power room, 41.
...Second output chamber, 42...Valve body, patent applicant
Sumitomo Electric Industries Co., Ltd. Agent Kama 1) Text - Figure 1 Figure 2 Hair

Claims (1)

[Claims] In a disc brake that generates braking force by pressing both sides of a disc rotor with a friction material that directly or indirectly receives the pushing force of an actuator including a brake piston, there is a hydraulic pressure introduction hole provided in the caliper body. In between the cylinder chamber and
The large diameter end of the pressure receiving area A_1 is the input hydraulic pressure P, and the pressure receiving area A_
A differential piston whose small diameter end is exposed to the output hydraulic pressure P', and a first spring which biases the piston toward the input chamber are provided. When the input hydraulic pressure reaches a predetermined value by receiving the output hydraulic pressure in the valve closing direction and the second spring force in the valve opening direction, the pressure receiving area of the input hydraulic pressure is the receiving pressure of the output hydraulic pressure. A limiting valve larger than the area is provided, and the set load of the first spring is set to P・(A_1-
A disc brake with a booster, characterized in that the value is set approximately equal to the value determined by the formula A_2).