JPH0223875Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an air disc brake, and more specifically to an air disc brake that minimizes the stroke cross during braking.

[Background of the idea]

Conventionally, general air disc brakes have screwed together the rotational force of a power screw rotated by driving force using an air chamber, etc., and are slidably fitted into a caliper cylinder so as to be unable to rotate around the axis. Usually, the forward force of the piston is used to press the friction pad against the rotor.

This operates in such a way that when the power screw rotates in the brake application direction, the screwed piston moves forward, and when the power screw rotates in the brake release direction, the screwed piston moves backward.

By the way, in such an air disc brake, the rotation around the axis of the piston is usually provided by the engagement of the piston with the radial inner surface of the rotor of the caliper, and Fig. 4 shows such an example. It shows. That is, both shoulder portions 35 and 36 of the front end rectangular pressing portion 34 of the piston 33 are made engageable with the inner surfaces 31 and 32 of the caliper 30, and this engagement prevents the piston body from rotating. There is.

However, in the case of such a configuration, it is difficult to avoid some play between the two engaging parts due to variations between products, etc., and this causes a stroke cross of the input drive mechanism when the brake is applied. I had a problem connecting. In other words, if the engagement between the inner surface 31 of the caliper and the shoulder 34 of the piston occurs when the brake is applied, a gap will be created between the inner surface 31 on the opposite side and the shoulder 35, and when the brake is released, it will take a long time to fill this gap. Since the piston is allowed to rotate along with the piston, this causes the above-mentioned stroke loss.

[Purpose of the invention] The present invention was made based on this point of view, and its purpose is to eliminate the entrainment of the piston caused by the power screw when the brake is released, and thereby reduce the input power when the next brake is applied. This is because the stroke cross of the drive mechanism has been eliminated.

[Summary of the idea]

The air disc brake according to the present invention, which was developed for this purpose, is characterized by the fact that rotation around the axis is restricted in the caliper cylinder, and the friction pads are pressed against the rotor by advancing and retracting in the axial direction. a power screw that is screwed together with the piston so that it can be screwed out and rotated relative to the piston, and whose movement in the axial direction is restricted; and a power screw that applies rotational force around the axis to the power screw. In the air disc brake equipped with a drive mechanism, the piston is provided with an engaging portion with the caliper that restricts the rotation when the piston moves forward, at a front end portion extending outside the caliper cylinder, and A spring is inserted between a portion of the piston to maintain constant contact with the engaging portion.

[Example of idea]

The present invention will be explained below based on a floating type air disc brake shown in the drawings.

In FIG. 1, 1 is a rotor, and 2 is a caliper arranged so as to straddle a part of the edge of the rotor 1, and is supported by a sliding support device (not shown) so as to be movable in the axial direction of the rotor.

The caliper 2 is also formed to have a cylinder leg 3 on one side of the rotor 1 and a reaction leg 4 on the other side of the rotor. 5 is cylinder leg 3
A rear bracket is integrated with the rear part of the axially penetrating cylinder 3a by a bolt (not shown),
Inside is the large diameter flange part 8 of the power screw 8.
A thrust bearing mechanism 9 is built in to support the smooth rotation of the shaft around the axis.

A piston 6 is slidably housed in the cylinder 4 so as to be slidable in the axial direction, and has a cylindrical shape, the front end of which is closed by an expansion plug 7, and a multi-striped female piston inside the cylinder. A screw 6a is formed. Further, the piston 6 is provided so that it cannot rotate around the axis because a projection (not shown) engages with an axial groove of the caliper.

Reference numeral 8 designates a power screw, the front end of which has a multi-threaded male threaded portion 8a on the outer periphery and is screwed into a multi-threaded female threaded portion 6a of the piston inner cylinder, and the rear end surface of the central large-diameter flange portion 8b is connected to the thrust bear mechanism 9. Further, the rear end portion 8c extends to the rear of the rear bracket 5, and has a spline formed on its outer circumferential portion, so that it cannot rotate around the axis of the rotational force transmission arm 11 connected to a drive source mechanism such as an air chamber. connected. 10 is a retaining washer.

With the above configuration, when the power screw 8 is rotated in the brake activation direction by the rotational force transmission arm, the piston 6 moves forward in the direction of the rotor 1 without rotating as the power screw 8 rotates. , the inner butt 12 is brought into pressure contact with the rotor 1. This pressure reaction force causes the caliper to slide to the right in the drawing, and the reaction leg 4 presses the outer butt 13 against the rotor 1, thereby producing a braking force of rotor clamping pressure.

The feature of this example is that in the air disc brake having the above structure, as shown in FIG. A rotation preventing engagement portion 6c that engages with the inner surface 2a of the straddle portion of the caliper 2 is provided on the side to prevent rotation,
On the opposite side of the piston front end rectangular portion 6b in the rotor circumferential direction, a spring force (a spring force) for maintaining the engagement between the inner surface 2a and the detent engaging portion 6c with respect to the piston 6 is provided between the piston front end rectangular portion 6b and the caliper 2. This is where a leaf spring 15 is provided which biases the counterclockwise spring force (as shown in Figure 2). The leaf spring 15 of this example is fixed to the caliper 2 with a bolt (not shown), and has a structure in which the bent and extended elastic tip snaps into engagement with the piston, and the spring force is applied to the power screw when the brake is released. Needless to say, the load is set to be sufficient to prevent the piston 6 from being rotated by the piston 8.

According to such a configuration, the piston 6 moves forward and backward within the cylinder 3a without causing any rotation around the axis, and therefore the piston does not rotate with respect to the power screw, so the power is reduced. There is no loss in the stroke of applying external force to the screw 8 due to the air chamber, etc.
In addition to being able to shorten the length of the air chamber in the stroke direction, there is also the advantage of eliminating the delay in the initial stage of brake operation.

In addition, in a type of device that incorporates an automatic gap adjustment device that adjusts the gap between the friction pad and the rotor in the drive force transmission arm etc. as the lining wears, it is possible to operate the brake without delay due to the adjustment. There is also the advantage that it can be obtained more favorably.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the plate spring 15 is replaced by a concave hole 6d formed in the rectangular portion 6b of the front end of the piston 6.
Using a coiled spring 16 fitted inside,
The engagement between the inner surface 2a of the caliper and the detent engaging portion 6c is maintained. Also in this example,
In addition to the advantage that the same effect as the above example can be obtained, there is also the advantage that a spring fixing screw is not required.

[Effect of idea]

According to the present invention described above, in the air disc brake, rotational restraint of the piston screwed with the power screw is preferably achieved, and as a result, the piston does not rotate together when the brake is released, so that the input drive mechanism is This has the effect of eliminating stroke crosses, and has great practical benefits.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a general configuration of an air disc brake to which the present invention is applied, Fig. 2 is a schematic diagram showing a structure for preventing rotation in one embodiment, and Fig. 3 is a diagram of another embodiment. FIG. 4 is a schematic diagram of the conventional example. 1... Rotor, 2... Caliper, 3... Cylinder leg, 3a... Cylinder, 4... Reaction leg,
5... Rear bracket, 6... Piston, 6a...
...Multi-thread female thread part, 6b... Front end rectangular part, 6c...
... Anti-rotation engaging portion, 6d... Recessed hole, 8... Power screw, 8a... Multi-threaded male thread portion, 8b... Large diameter flange portion, 8c... Extending rear part, 8d, 8e,
8f... Grease filling channel (channel), 9... Thrust bearing mechanism, 15... Leaf spring, 16...
coil spring.

Claims (1)

[Scope of utility model registration request] The piston is slidably fitted in the caliper cylinder with restricted rotation around the axis, and presses the friction pad against the rotor by advancing and retracting in the axial direction, and the piston is screwed together to allow relative screwing and rotation with this piston. In an air disc brake equipped with a power screw whose movement in the axial direction is restricted and a drive mechanism that applies rotational force around the axis to the power screw, the piston has a An engaging portion with a caliper that restricts the rotation when the piston moves forward is provided at the extended front end, and a spring is provided between the caliper and a portion of the piston to keep the engaging portion in constant contact. An air disc brake characterized by an interposed air disc brake.