JPH03244836A - Disk brake - Google Patents

Abstract

PURPOSE:To enhance the extent of braking torque at the initial stage by setting a piston at the inlet side in the disk rotational direction, out of two pistons set up around the disk, so as to press the disk earlier than the other, at the initial stage of braking. CONSTITUTION:When a brake fluid is taken into each of cylinders 12 and 13, two pistons 14, 15 move forward and thereby a friction pad 8 on one side is pressed by a disk 2. With this reaction, a part, where these cylinders 12, 13 of a caliper 6 are formed, is moved in the direction apart from the disk 2, and a claw part 20 presses a friction pad 9 to the disk 2. At this time, in order to make a sliding resistance of the inlet side piston 14 smaller than that of the outlet side piston 15, depth of a ring groove 21 at the inlet side is formed to be deeper than an outlet side ring groove 22. Therefore the inlet side piston 14 operates earlier than the other and an operating lag of a brake is shortened. In addition, since moment in the inlet side piston 14 is larger than that of the outlet side one, initial braking force becomes higher than the case that operates the outlet side piston 15 earlier.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hydraulic disc brake used in a brake system of a vehicle or the like.

(Prior art) Conventionally, vehicles with a large body weight or high output require a large braking force, so a plurality of pistons are arranged in the circumferential direction of a disk for one friction pad. Some brakes are equipped with a disc brake that increases the pressing area and evenly presses the friction pad against the disc to obtain a large braking torque.

However, with this type of disc brake, there is a delay in brake operation before the brake pedal is depressed and braking torque is generated due to friction in the sliding parts and gaps between the disc and the friction pad. In order to improve the grip feeling at the initial stage of braking to improve the pedal feel and to secure braking torque at the initial stage of braking, it is desirable to shorten this delay in brake operation as much as possible. Therefore, in the past, the amount of rollback (return amount of the piston) of each piston was reduced to narrow the gap between the disk and the friction pad, and the sliding resistance of each piston was reduced to reduce the piston's operating speed. We are dealing with this by speeding up the process.

(Problem to be solved by the invention) However, if the amount of rollback of each piston is made too small, the friction pad will easily cause a drag phenomenon that occurs when the friction pad comes into contact with the disk, which will accelerate the wear of the friction pad. There were some problems.

Additionally, if the sliding resistance is made too small in order to increase the operating speed of each piston, knock-hack (deflection of the disc due to twisting of the suspension) will cause the piston to return to its original position, increasing the gap between the disc and the friction pad. There was a problem in that there was a risk that the pedal feel link would worsen even further.

The present invention has been made in view of the above problems, and its purpose is to provide a disc rake that provides good brake pedal feeling and can secure braking torque at the initial stage of braking. It is in.

(Means for Solving the Problems) The disc brake of the present invention has a plurality of pistons arranged in the circumferential direction of the disc for pressing a friction pad against the disc, and when brake fluid pressure is supplied, the pistons Among the pistons, the piston arranged on the inlet side in the rotational direction of the disk is set to press the disk before the other pistons.

Further, a plurality of pistons for pressing the friction pad against the disk are arranged in the circumferential direction of the disk, and among the plurality of pistons, the amount of rollback or sliding of the piston arranged on the inlet side in the rotational direction of the disk is It is characterized in that the dynamic resistance is set smaller than the rollback amount or sliding resistance of other pistons.

(Operation) According to the above configuration, when brake fluid pressure is transmitted to the piston, the piston on the inlet side in the rotational direction of the disc first presses the friction pad, shortens the brake activation delay and generates braking torque. It becomes possible. Also, the part that receives the torque of the friction pad is located at the rear of the rotational direction of the disc, and with that part as a fulcrum, the moment applied to the piston or friction pad on the inlet side is greater than the moment applied to the piston or friction pad on the exit side. Therefore, the braking torque at the initial stage of braking can be increased compared to the case where the piston on the exit side first presses the friction pad.

In addition, if the rollback amount of the piston on the inlet side is set small, the gap between the disc and the friction pad is reduced by the piston, and the delay in brake operation can be shortened. The braking torque at the initial stage of braking can be increased by the moment. At this time, if the piston on the exit side is set to the normal rollback amount, an excessive dragging phenomenon will not occur.

If the sliding resistance of the piston on the inlet side is set to a small value, the operating speed of the piston on the inlet side will become faster, which will shorten the delay in brake activation and, as mentioned above, reduce the braking torque at the initial stage of braking. It is possible to increase At this time, if the knock-hack is suppressed by the sliding resistance of the piston on the exit side, the piston will not return significantly.

(Example) Next, embodiments of the present invention will be described based on the drawings.

The disc rake of this embodiment is a caliper floating type disc rake. First, the overall configuration will be explained based on FIG. 1. A carrier 1 is fixed to the non-rotating portion of the vehicle, and a disk 2 is attached to an axle (not shown) on the rotating portion side. Legs 3.4 formed at both ends of the carrier 1 in the rotational direction of the disk 2 are each provided with a bottle hole (only one is shown) in the axial direction of the disk 2.
A caliper support pin 7 fixed to the caliper 6 is slidably fitted into the pin hole 5. Therefore, the caliper 6 is supported by the carrier l so as to be movable in the axial direction of the disk 2.

A pair of friction pads 8 and 9 are arranged on both sides of the disc 2, and the friction pads 8 and 9 are attached to the legs 3.4 of the carrier l.
The torque receiver formed in is held in the carrier l so as to be slidable in the axial direction of the disk 2 along a surface 10.11 (shown in FIG. 4). The friction pad 8.9 is
It consists of linings 8a, 9a that press against the disk 2, and back metals 8b, 9b that support the linings 8a, 9a.

Said carrier l has two cylinders 12. l:1 is provided along the circumferential direction of the disc 2, and a piston 14.15 is slidably provided in the cylinder 12.13, and when the piston 14.15 receives brake fluid pressure, One of the friction pads 8 is connected to the disc 2 from the back metal side 8b.
to press.

A seal ring 16 is provided on the inner circumference of the cylinder 22.13 to prevent oil leakage by slidingly contacting the outer circumference of the piston 14.15.
．． 17 cylinders are provided, and cylinders 12.1: ]
A boot 1 is provided between the opening of the piston 14.15 and the outer periphery of the piston 14.15 to prevent water and dust from entering the cylinder 12.13.
8.19 is installed.

The caliper 6 has a cylinder 12.1 across the disc 2.
A claw portion 20 extending on the opposite side of the claw portion 2 is provided.
0 is in contact with the back metal 9b side of the other friction pad 9.

According to the above configuration, when brake fluid pressure is introduced into the cylinder 12.13, the piston 14. Is moves forward and presses one of the friction pads 8 against the disc 2, and as the reaction force moves the part of the caliper 6 away from the disc 2 where the cylinders 12 and 13 are formed, the pawl 20 or the other friction pad 9 is pressed against the disk 2,
- Braking torque is generated by sandwiching the disc 2 between the pair of friction pads 8 and 9.

Next, the main parts of the present invention will be explained.

First, in the first embodiment, the amount of rollback of the piston 14 on the inlet side in the rotation direction R of the disk 2 (rotation when the vehicle moves forward) is made smaller than the amount of rollback of the piston 15 on the exit side.

The amount of rollback is determined by the seal links 16.17 formed on the inner circumference of the cylinder 12.13 (the seal links 16.17 have the same shape), as shown in FIGS. 2(a) and (b).
A chamfered portion 23.24 is formed over the entire circumference at the edge of the annular groove 2, 22 on the cylinder opening side, and the size of the chamfered portion 23.24 can be arbitrarily set. Therefore, in order to reduce the amount of rollback of the piston 14 on the inlet side in the rotational direction of the disk 2, an annular groove 21 formed in the cylinder 12 on the inlet side
The chamfered portion 23 is made smaller than the chamfered portion 24 of the annular groove 22 formed in the cylinder 13 on the outlet side.

As a result, the gap between the disk 2 and the friction pad 8 is narrowed by the amount of rollback of the piston 14 on the inlet side. Therefore, when brake fluid pressure is supplied to the cylinders 12 and 13 and the piston 14 on the inlet side first presses the friction pad 8 to generate braking torque, the narrower gap causes the brake to operate more than before. You can shorten the delay. At this time, since the rollback amount of the piston 15 on the exit side is the same as before, both pistons 14.
15 will not cause excessive dragging of the friction pad 8.

Further, as shown in FIG. 4, the braking torque of the friction pad 8 is received by the torque receiving surface II on the exit side, and the moment Mr, 4 (
FPrHX 11x) is the moment Mour (FPoutXρ
Since the amount of rollback of the piston 15 on the exit side is set smaller, the braking torque at the initial stage of braking can be increased.

Here, using FIGS. 5 and 6, the braking torque T and the brake fluid pressure (
To explain the relationship with P (input hydraulic pressure), with conventional disc brakes, there is a delay in brake operation, so the hydraulic pressure
Braking torque starts to be generated when the hydraulic pressure reaches 22, or if the operation delay is shortened as in this embodiment, the braking torque starts to generate when the hydraulic pressure reaches 22. Therefore, as shown by the solid line in FIG. 6, the braking torque can be increased compared to the conventional system shown by the broken line.

In the second embodiment, the sliding resistance of the piston 14 on the inlet side in the rotational direction of the disk 2 is made smaller than the sliding resistance of the piston 15 on the exit side.

As shown in FIGS. 3(a) and 3(b), the sliding resistance is set by varying the depth of the annular groove 21.22 into which the sealing link 16.17 is inserted. Therefore, disk 2
In order to reduce the sliding resistance of the piston 14 on the inlet side in the rotation direction of the piston 14, the depth of the annular groove 21 provided on the inner periphery of the cylinder 12 on the inlet side is made deeper than the depth of the annular groove 22 on the outlet side. ing. In this way, seal ring 1
By lowering the elastic force of 6, the sliding resistance is reduced.

As a result, the piston 14 on the inlet side moves faster, brake fluid pressure is supplied to the cylinder 12.13, and when the piston 14 on the inlet side presses the friction pad 8 and generates braking torque, The brake activation delay can be made shorter than before. In addition, even if a knock pack occurs, it is suppressed by the piston 15 on the exit side, so each piston 14, 15 does not return much. Therefore, the braking torque at the initial stage of braking can be increased compared to the case where the sliding resistance of the piston 15 on the exit side is set small.

In addition, although this embodiment shows an example in which the present invention is applied to a caliper floating type disc brake, the present invention is not limited to this. For example, a caliper fixed type disc with pistons facing each other on both sides of the disc The present invention may be applied to a tree. In addition, in this embodiment, the present invention is applied to a case in which two pistons 14.15 are provided for one friction pad 8, or is applied to a case in which three or more pistons are provided for one friction pad. You may.

Further, the setting of the rollback amount and the setting of the sliding resistance of the present invention are not limited to the above configurations; for example,
The elastic modulus of the seal ring may be changed.

(Effects of the Invention) As explained in detail above, the present invention reduces the amount of rollback of the piston provided on the inlet side of the disc pulp and reduces the sliding resistance. Since the piston pushes the friction pad against the disc first, the delay in brake activation can be shortened.

Therefore, it is possible to improve the feeling of bite at the initial stage of braking and improve the pedal feel link, and also to increase the braking torque at the early stage of braking.

Further, since the present invention has a simple configuration, the manufacturing cost does not increase, and it can be applied to conventional disc brakes without major changes.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the disc brake of the present invention, FIGS. 2(a) and (b) are enlarged sectional views of essential parts showing an example of rollback settings, and FIG. 3(a) ), (b) are enlarged cross-sectional views of essential parts showing an example of setting the sliding resistance, Figure 4 is a schematic diagram showing the moment applied to each piston or friction pad, and Figure 5 is shown in Figure 1. Figure 86 is a diagram showing the relationship between disc brake braking torque and input brake fluid pressure. It is an enlarged view of part A in FIG. 5. 2...Disk 8...Friction ballad 14...Piston on the inlet side 15...Piston on the outlet side

Claims (2)

[Claims] (1) A plurality of pistons for pressing friction pads against the disk are arranged in the circumferential direction of the disk, and when brake fluid pressure is supplied, one of the plurality of pistons is placed on the inlet side in the rotational direction of the disk. A disc brake characterized in that a piston placed in the disc presses the disc before other pistons. (2) A plurality of pistons for pressing the friction pad against the disk are arranged in the circumferential direction of the disk, and among the plurality of pistons, the amount of rollback of the piston arranged on the inlet side in the rotational direction of the disk or A disc brake characterized in that sliding resistance is set smaller than the rollback amount or sliding resistance of other pistons.