JPH02102935A - Brake cylinder in disk brake - Google Patents

Abstract

PURPOSE:To save an independent hydraulic pressure controller by accommodating a first hydraulic pressure control mechanism for reducing the supply of hydraulic pressure to a second liquid chamber with a constant rate when the pressure of a first liquid chamber reaches to a first given pressure and a first spring for energizing it to open. CONSTITUTION:When the hydraulic pressure of a fluid source is pressed, while the internal pressure of a first liquid chamber A and a second liquid chamber B is equally raised by opening the valve of a first hydraulic pressure control mechanism V1, a main piston 8 is pressed to start the operation of a service brake. When the hydraulic pressure of the fluid source is subsequently pressed, the hydraulic pressure is increased to make an operating force to a right outer peripheral direction of a plunger 16 higher than the spring force of a first spring 20. Then, a valve head 16a is seated on a valve seat 18 to temporarily close a flow passage to the second liquid chamber B, but from the relation of a pressure receiving effective diameter D larger than d, the first hydraulic pressure control mechanism V1 is intermittently operated.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a brake cylinder for a disc brake for a vehicle, and more particularly to a brake cylinder having a hydraulic pressure control function.

<Prior Art> Recently, disc brakes are increasingly being used for both the front and rear wheels of vehicles.

When disc brakes are used for both the front and rear wheels, as a means to prevent the rear wheels from locking up early, conventionally, an independent hydraulic pressure control is installed in the piping from the mask cylinder, which is the fluid source, to the rear wheel brakes. We are dealing with the situation by deploying equipment.

Problems to be Solved by the Present Invention The conventional type of providing an independent hydraulic pressure control device has the following problems.

(a) Not only is there a large number of parts required for the installation of the hydraulic pressure control device, but the hydraulic pressure control device is also expensive.

(b) Since there are many joints in the piping, a great deal of labor is required to join the pipes, and there are many dangerous points where fluid leaks may occur.

OBJECTS OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a brake cylinder for a disc brake as described below.

(a) A brake cylinder in a disc brake that can omit an independent hydraulic pressure control device and perform the same hydraulic pressure control function as before.

(b) A brake cylinder in a disc brake that can reduce the number of piping connections that can cause fluid leaks.

Configuration of the Present Invention> Examples of the present invention will be described below with reference to the drawings.

<A> Description of disc brake (Fig. 1) Fig. 1 shows a longitudinal section of a disc brake.

The structure of the disc brake shown in the figure will be explained below, and the structure other than the brake cylinder is the same as the known structure.

1 is a rotor that rotates together with the wheels, etc.; 2 is a carrier fixed to a stationary part of the vehicle body; 3 is a caliper that is slidably supported by the carrier 2 across the rotor 1; and 4 and 5 are rotors 1
A pair of pads placed on both sides of the

A brake cylinder 6 is provided on the caliper 3.

<Port> Brake Cylinder In this embodiment, a brake cylinder 6 of a type that incorporates a second hydraulic pressure control mechanism that directly transmits pressure from a fluid source to a brake action section when the hydraulic pressure is high will be described.

The brake cylinder 6 has three functions: a brake function, an automatic gap adjustment function that automatically adjusts the gap between the rotor 1 and the pad 4.5, and a hydraulic pressure control function due to the structure described later.

7 is the housing, and the large diameter cylinder hole 7 is sequentially inserted from the left side of the housing.
a, a medium-diameter cylinder hole 7b and a small-diameter cylinder hole 7c are drilled, and a bottomed hole 7d perpendicular to the bottom of the bag-shaped small-diameter cylinder hole 7c is bored.

A main piston 8 having a stepped hole 8a with a bottom is slidably fitted into the large diameter cylinder hole 7a.

A small diameter shaft portion 9a of a stepped sub-piston 9 is rotatably fitted into the bottomed stepped hole 8a of the main piston 8.

A nut member 10 with a flange is slidably but unrotatably fitted into the bottomed hole 9b of the sub-piston 9.

Furthermore, one side 11a of a bolt member 11 having a multi-thread thread is screwed into the nut member 10.

Further, in order to perform the parking brake function, a camshaft 13 having an eccentric groove 13a is fitted into the bottomed hole 7d of the housing 7.

The eccentric groove 13a of the camshaft 13 and the bolt member 11
A rod 12 is interposed between the rod 12 and the end of the head 11b of the camshaft 13, and is configured to non-rotationally link the operation of a remote control device connected to the end of the camshaft 13 to the bolt member 11. are doing.

14 is an adjustment spring, which is compressed between the nut member 10 and a retaining ring 15 fixed to the main piston 8;
The stepped surface 9c of the sub-piston 9 is connected to the stepped surface 8b of the main piston 8.
A friction clutch mechanism is formed between the two surfaces 9c and 8b.

Reference numeral 16 denotes a substantially cylindrical plunger, which has a valve head 16a on the outer periphery on the left side in the drawing, and a housing 7 on the outer periphery on the right side in the drawing.
It is slidably fitted into the small diameter cylinder hole 7c.

Further, the head 11b of the bolt member 11 is slidably inserted into the plunger 16.

17 is a substantially cylindrical stepped sleeve, the large diameter portion 17a of which is connected to the large diameter cylinder hole 7a of the housing 7, and the small diameter portion 17
b are slidably fitted into the medium diameter cylinder holes 7b, respectively.

The stepped sleeve 17 and the plunger 16 define a first liquid chamber A that communicates with the hydraulic pressure introduction lower e in the small diameter part 17b (Ill), and a second liquid chamber B in the large diameter part 17a.
is defined.

Further, the relationship between the pressure receiving outer diameter D' of the large diameter portion 17a and the pressure receiving outer diameter d' of the small diameter portion 17b is set as D'>d'.

18 is a valve seat attached to the protrusion 17c on the inner circumference of the stepped sleeve 17.

This valve seat 18 and the valve head 16a create a first liquid chamber A.
A first hydraulic pressure control mechanism V is configured to reduce the hydraulic pressure from the liquid chamber B to the second liquid chamber B at a constant rate.

Further, the relationship between the effective pressure receiving diameter of the valve head 16a and the effective pressure receiving diameter d of the right outer periphery of the plunger 16 is set as D>d.

Note that a valve seat 18 may be attached to the valve head 16a of the plunger 16, and the valve seat 18 and the protrusion 17c of the stepped sleeve 17 may constitute the first hydraulic pressure control mechanism v1.

The amount of movement of the plunger 16 and the stepped sleeve 17, that is, the distance ti e from the right end surface of the plunger 16 to the bottom surface of the small diameter cylinder hole 7c, and the distance from the right end surface of the stepped sleeve 17 to the bottom surface of the medium diameter cylinder hole 7b. By setting the distance relationship e<L, the stepped sleeve 17
A second hydraulic pressure control mechanism V2 is configured to keep the liquid chamber A and the second liquid chamber B normally open.

The plunger 16 is operated by a first spring 20 compressed between a retaining ring 19 attached to the inner circumference and the head 11b of the bolt member 11, and the stepped sleeve 17 is operated by a protrusion 17c and a medium diameter cylinder hole 7b. The first hydraulic pressure control is carried out by being pressed and biased by the second springs 21 contracted between the bottom surfaces, and by restricting leftward movement of both 16 and 17 by the retaining rings 22. Mechanism vI is open at low pressure.

<Effect> Next, the action of the brake cylinder 6 will be explained.

<B> Hydraulic pressure i control (Fig. 1.3) When the liquid pressure of the fluid source is increased, the first liquid chamber A and the second liquid chamber B are opened by opening the first liquid pressure control mechanism v1. The internal pressure increases equally and pushes the main piston 8 to start the service brake action.

The hydraulic characteristics at this time are shown by the straight line OX in FIG.

When the fluid pressure of the fluid source is subsequently increased, the fluid pressure rises and the force acting on the right outer periphery of the plunger 16 overcomes the spring force of the first spring 20, causing the valve! Although the FJ 16a sits on the valve seat 18 and temporarily closes the flow path to the second liquid chamber B, the first hydraulic pressure control mechanism V1 operates intermittently due to the effective pressure receiving diameter Dad. .

As shown in FIG. 3, the hydraulic pressure characteristics at this time are a straight line XY that is inclined from the broken line XZ because the pressure is reduced at a constant rate. Therefore, premature locking of the wheels will be prevented.

If one of the two piping systems fails for some reason, the braking force will decrease, so if the fluid pressure of the fluid source is suddenly increased, the large diameter portion 17a of the stepped sleeve 17 , due to the difference in force acting on the small diameter portion 17b, the second spring 21 is compressed and the second hydraulic pressure control mechanism V2 is activated.
operates to the right and maintains the first hydraulic pressure control mechanism v1 in an open state, so that the hydraulic characteristics obtain the straight line YZ and the following straight line ZZ' in FIG. 3, and the braking force is improved.

<Exposure> The automatic gap adjustment mechanism when the automatic gap adjustment pad 4.5 is worn out will be explained.

If the service brake is activated when the pad 4.5 is worn, the amount of relative movement between the nut member 10 and the bolt member 11 will exceed the amount of backlash of the multi-threaded thread, and the adjustment spring 14 will move at an initial low pressure. The nut member 10 and the sub-piston 9 are rotated as two bodies by the spring force, thereby extending the effective length of the nut member 10 and the bolt member 11, and automatically closing the gap between the rotor 1 and the pad 4.5.

In addition, when the hydraulic pressure gradually increases to the extent that the caliper 3 and the like begin to elastically deform, the axial force acting on the small diameter shaft portion 9a of the sub-piston 9 causes the stepped surface 9C and the stepped surface of the main piston 8 to 8b increases, the secondary piston 9
rotation is prevented and the adjustment spring 14 is deflected,
The self-regulating action is stopped.

<C> Parking Brake Operation When a remote control device (not shown) connected to the end of the camshaft 13 is activated, the camshaft 13 rotates, pushes out the rod 12, and the bolt member 11 moves to the left in the drawing.

As the bolt member 11 moves, the nut member 10, the sub-piston 9 and the main piston 8 which are screwed onto the bolt member 11 are mechanically pushed out.

As a result, the pad 4 is pressed to the rotor 1, and the pad 5 is pressed to the rotor 1 by the reaction force, so that the parking brake is activated.

<Other Embodiments 1> (Fig. 2) Next, a type that incorporates a second hydraulic pressure control mechanism that causes the pressure reduction gradient of the first hydraulic pressure control mechanism to rise suddenly from the slope line when the hydraulic pressure is high will be explained. do.

Since this embodiment differs from the previous embodiment only in the second hydraulic pressure control mechanism, explanations of the various parts having substantially the same functions will be omitted.

In this embodiment, a second hydraulic pressure control mechanism v'2 is provided inside the bolt member 11'.

That is, the bolt member 11' is provided with a passage 11''d that communicates the first liquid chamber A and the second liquid chamber B through its axis, and the valve seat 11 is provided in the middle of this passage 11'd. 'C, and a second spring 21 which strengthens the ball valve 30 on this valve seat 11'c.
' to form a second hydraulic control mechanism v'2.

Furthermore, the operation of this embodiment is the same as the operation of the previously described embodiment when the piping system is normal, so a description thereof will be omitted.

In addition, if one of the two piping systems fails, if the fluid pressure of the fluid source is suddenly increased, the force acting on the ball valve 30 will overcome the spring force of the 492nd spring 21'. When the valve is opened, the hydraulic characteristic of the second hydraulic pressure control mechanism v'2 shows YY' in FIG. 3, and the braking force increases.

<Other Embodiments 2> Furthermore, although the embodiments described above have a parking brake function and an automatic clearance adjustment function, it is of course applicable to known disc brakes that do not have these functions.

Furthermore, the present invention may be applied to a type of disc brake in which brake cylinders are respectively disposed on the back surfaces of a pair of pads.

Effects of the Present Invention> Since the present invention is as described above, it has the following effects.

(A) By incorporating the hydraulic pressure control mechanism inside the disc brake, an independent hydraulic pressure control device can be omitted.

Therefore, the number of parts can be reduced as a whole, and it is also inexpensive.

<Exposure> There is no need to attach an independent hydraulic pressure control device to the vehicle body, and there is no longer a connection part to the hydraulic pressure control device in the middle of piping.

Therefore, not only can these assembly operations be reduced, but there are also fewer places to worry about fluid leakage.

In addition, air bleeding can be done using only disc brakes.

<C> Since both the first and second hydraulic pressure control mechanisms are provided coaxially with the axis of the brake cylinder, machining is easy and they can be arranged without being restricted by the piston diameter.

(2) Since the hydraulic pressure control mechanism is shared by the bolt member that serves both the parking brake mechanism and the automatic gap adjustment mechanism, the structure is simple.

[Brief explanation of drawings]

Fig. 1: A longitudinal sectional view of a disc brake showing an embodiment according to the present invention Fig. 2: A longitudinal sectional view of a disc brake showing another embodiment Fig. 3: A diagram showing hydraulic characteristics

Claims (2)

[Claims] (1) In a disc brake of the type that presses a pair of pads arranged on both sides of the rotor by the action of a brake cylinder of a caliper arranged straddling the rotor, a first fluid chamber communicating with a fluid source; , a second liquid chamber that operates the piston on the back side of the pad, and when the pressure in the first liquid chamber reaches a first predetermined pressure, a second liquid chamber
a first hydraulic pressure control mechanism that reduces the hydraulic pressure supplied to the liquid chamber at a constant rate; a first spring that biases the first hydraulic pressure control mechanism in the opening direction; and the first predetermined pressure. a second hydraulic pressure control mechanism that slides the stepped sleeve to maintain the first hydraulic pressure control mechanism in a normally open state when a second predetermined pressure set higher is reached; A brake cylinder for a disc brake, which includes a built-in second spring that is biased and held in a stationary state until a second predetermined pressure is reached. (2) In a disc brake of the type that presses a pair of pads arranged on both sides of the rotor by the action of a brake cylinder of a caliper arranged straddling the rotor, a first fluid chamber communicating with a fluid source; , a second liquid chamber that operates the piston on the back side of the pad, and when the pressure in the first liquid chamber reaches a first predetermined pressure, a second liquid chamber
a first hydraulic pressure control mechanism that reduces the hydraulic pressure supply to the liquid chamber at a constant rate; a first spring that biases the first hydraulic pressure control mechanism in the valve opening direction; and the first predetermined spring. a second hydraulic pressure control mechanism that raises the hydraulic pressure from the first liquid chamber to the second liquid chamber above the first pressure reduction gradient when a second predetermined pressure set higher than the pressure is reached; A brake cylinder for a disc brake that includes a second spring that biases a second hydraulic pressure control mechanism in a closing direction.