JPH0226092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic gap adjustment device that always maintains a constant gap between a rotor and a friction pad in an air brake (air disk or air S-cam drum) when the brake is not being applied. .

In general, air brakes were developed when disc brakes, which were mostly hydraulically actuated, began to be used on large vehicles such as trucks, and were developed in air chambers. One type uses supplied air to press the push rod and rotates the shaft coming out of the caliper, which rotates the power screw built into the caliper to obtain pressure on the piston pad, and the other type has a wedge mechanism at the tip of the push rod. There is a known type in which a pad is provided and a pad pressing force piston is moved by its pushing and spreading force.

By the way, even in such an air disc brake, as is known in known hydraulically operated disc brakes, etc., as the lining wear of the friction pads progresses, the gap between the rotor and the friction pads during non-braking occurs. If the increase in the gap amount is left unaddressed, problems such as a delay in the initial brake operation or an increase in the stroke of the drive part of the brake drive mechanism (specifically, the air chamber in the case of an air disc brake) may become undesirable problems for the brake system. It will appear.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an automatic gap adjustment device that can automatically adjust such an increase in the gap in the air brake and keep the gap amount substantially constant at all times.

Regarding the configuration of such an automatic gap adjustment device, it is possible to apply one found in known hydraulically operated disc brakes, etc., but air disc brakes use pistons that press friction pads against the rotor. Since the drive mechanism of the brake is completely different from a hydraulically operated type, it is not possible to simply apply a known mechanism, and a suitable mechanism compatible with the structure of the air disc brake is desired. From this point of view, it is an object of the present invention to provide an automatic gap adjustment device suitable for the above-mentioned power screw type air disc brake and the like.

In other words, for example, in a power screw type air disc brake, the pad pressing piston is slidably fitted into the caliper cylinder in a state where it cannot rotate around the axis, and the rotation of the power screw that is screwed onto this piston. The piston is screwed in and out relatively, and the power screw is provided so that it cannot move in the axial direction, thereby allowing the piston to move forward and backward, and the rotation of the power screw (In other words, the rotation that causes the piston to move forward and backward relative to each other; hereinafter referred to as "screw-out rotation" and "screw-in rotation") is the rear end of the power screw protruding from the caliper (the front end that screws into the piston). This is achieved by reciprocating an arm connected to extend in the radial direction from the opposite side (opposite side) via a push rod that reciprocates by driving an air chamber.

Therefore, in an air disc brake with such a configuration, as the lining wear of the friction pad progresses, the piston rest position (return position when the brake is released) is repositioned forward toward the rotor as necessary. On the other hand, it is desirable that the reciprocating range of the air chamber and the arm is always kept constant regardless of the adjustment of the piston position.

The present invention has been made from this point of view, and includes a unidirectional structure that changes a slight amount of rotation of the power screw in addition to the arm rocking in the part that transmits the swing of the arm as the rotation of the power screw. A feeding mechanism is provided, and this one-way feeding mechanism synergistically causes the screw-out rotation of the power screw when the amount of advance of the piston during brake operation increases as the lining wear of the friction pad progresses. As a result, the amount of screw-in rotation of the power screw caused by the return swing of the arm is made relatively smaller than the amount of screw-out rotation, and the piston moves away from the rotor when the brake is released. The backward return position is repositioned to the rotor side. Incidentally, such an automatic gap adjustment device can be applied as is to the camshaft rotation drive mechanism of the existing air S-cam drum brake.

The gist of the present invention is to provide an air brake having an arm drive mechanism for rotating a power screw shaft of a disc brake or an operating camshaft of a drum brake, in which the swing of the arm is normally controlled by a built-in mechanism. is provided so as to be transmitted to the power screw or the actuating cam through an engagement portion between a worm maintained in a non-rotating state and a worm wheel pivoted on the rear end of the power screw or the actuating cam, a circular adjusting gear that is coaxial with the axis of the worm and has a one-way gear on its outer periphery; and a circular adjusting gear that is capable of reciprocating the outer periphery of the adjusting gear in a substantially tangential direction, and between the arm and the arm drive mechanism. and an adjuster steering member swingably connected to the connecting portion of the controller, and when the arm swing amount during braking exceeds a predetermined constant value, the adjuster steering member adjusts the adjuster steering gear, which is the one-way gear. The automatic gap adjustment device for an air brake is characterized in that it comprises a one-way feed mechanism that rotates the power screw or the operating cam in a direction to provide screw rotation to the power screw or the operating cam.

Furthermore, the present invention provides a clutch section between the worm and the adjusting gear in the above-mentioned device, and this clutch section is used, for example, when the resistance to rotation of the power screw increases (i.e., when the friction pads are pressed against the rotor). If the caliper reaction pawl elastically deforms and causes the piston to move forward after the caliper is closed, it is possible to prevent the so-called gap adjustment from becoming disconnected.

Furthermore, manual adjustment can be carried out without causing slippage of the clutch transmission section, and the condition of the clutch surface can be maintained.

Hereinafter, the present invention will be explained based on an embodiment of the air disc brake shown in the drawings.

In the figure, 1 is the rotor, 2 is a fixed support (hereinafter referred to as support) fixedly installed so as to straddle a part of the green part of the rotor, and an arm that straddles the rotor at two positions spaced apart in the circumferential direction of the rotor. Part 3,
3.

4 is an arm 3 that supports the edge of this rotor 1;
It is a caliper arranged so as to straddle between 3,
A leg 5 on one side of the rotor 1 incorporates a pad pressing mechanism, and a leg 6 on the other side of the rotor 1 forms a reaction claw.

The caliper 4 is supported so as to be movable in the axial direction of the rotor with respect to the support 2 via pin slide type sliding support devices 7, 7 each including a slide pin attached to both sides in the circumferential direction of the rotor.

Reference numerals 8 and 9 designate a pair of friction pads that are arranged to face each other with the rotor 1 in between, and are provided so that the torque during braking is directly received by the arm portions 3 and 3 on both sides of the support 2. The side friction pad 8 is supported by the support 2, and the outer side friction pad 9 is supported by a slide pin so as to be slidable in the axial direction of the rotor.

A cylinder 10 is formed on one side 5 of the caliper 4, and a cylindrical pad pressing piston 11 is slidably fitted thereto. A threaded portion 12 is formed in the inner cylindrical portion of the piston 11 and is threaded into the front end of a power screw 13, which will be described later. The power screw 13 is slidably fitted through a through cylinder 18 of a housing 17 bolted to the rear part of the cylinder 10 of the caliper leg 5 (on the opposite side from the rotor), and the piston 11 is screwed into the front end of the housing 17. Part 1
A large-diameter flange 15 is formed in the axially intermediate portion of the housing 17 so that the axial force can be supported by the housing 17 via a thrust bearing 19. The rear end 1 inserted to the outside through the
6 is connected to an arm 20 via a push rod from the air chamber.

The connection structure between the rear end of the power screw 13 and the arm 20 extending in its radial direction is used to transmit the movement of the one-way feed mechanism for adjustment, which will be described later, to the power screw in addition to transmitting arm swing. To,
A worm 29 (see FIG. 3) built into the arm 20 and normally maintained in a non-rotating state, and a worm wheel 28 (a third The swinging motion of the arm is transmitted as rotation of the power screw through the engaging portion (see figure).

The cylinder 18 of the housing 17 is slidably connected to the power screw 13 via a bush. Note that the inner space 21 of the cylinder 10 that accommodates the piston 11 is filled with lubricant (grease). 22 is a bracket for mounting the air chamber.

Reference numeral 23 denotes a load distribution plate, which is disposed so as to be engaged with the distal end surface of the piston 11 in a convex-concave manner, and inserted into the back surface of the inner friction pad 8 in a concave-convex manner to prevent the piston 11 from rotating. This is to effectively transmit the pressing force of the piston 11 to the friction pad 8.

With this configuration, when the arm 20 swings (swings when the brake is applied), the power screw 13 is screwed out and rotated accordingly, so that the piston 11 moves forward without rotating (relative to the power screw). (relative forward rotation) to press the friction pad 8 against the rotor 1.

Therefore, the caliper 4 slides to the right in FIG. 1 due to the reaction force while being supported by the sliding support devices 7, 7, and presses the outer side friction pads 9 against the rotor 1. Braking force is generated by clamping pressure.

Next, the structure of the swing drive mechanism of the arm 20 and the one-way feed mechanism for gap adjustment will be explained.

Figure 3 is a front view of the air disc brake (second
The air chamber 24 is assembled to the bracket 22 fixed to the caliper 6.
At the tip of the push rod 25 extended from the
A clevis 26 is attached and connected in a swingable manner,
The clevis 26 is pivotally connected to the extending end of the arm 20 via a pivot pin 27.

A worm 29 is attached to the connecting portion of the arm 20 to the rear end 16 of the power screw by a shaft 29a.
is rotatably supported and built-in, and this worm 29 meshes and engages with the worm wheel 28 that is pivotally attached to the rear end 16 of the power screw, as described above. Therefore, when a force is applied to the arm 20 by the air chamber 24 to cause its extended end to swing clockwise in the figure 3 (direction B in the figure), the built-in worm 29 also swings clockwise in the figure 3. The worm wheel 28 meshing with the worm wheel 28 is rotated in the same direction, causing the rotation of the rear end 16 of the power screw (the above-mentioned screw rotation).
Since the rotational force around the axis about 9a does not particularly act, the worm wheel 28 and the power screw 1
The magnitude of the screw-out rotation of No. 3 is the same as the amount of swing of the arm 20.

20a, 20a are holes that slidably support the worm shaft 29a.

Furthermore, when the brake is released, the air chamber 24 returns to its initial state, so the arm 20 also swings back to its initial position (the state shown in FIG. 3), and due to the engagement relationship between the worm 29 and the worm wheel 28, the arm The power screw 13 also returns to its initial position and rotates (the above-mentioned screw-in rotation) in an operation completely opposite to that during swinging (when the brake is applied), and the amount of rotation is the same as the amount of arm return swinging.

Note that the movement of the worm 29 macroscopically ignoring the rotation around the axis 29a (microscopically there is some rotation, but this point will be discussed later) is as follows:
This is based on the assumption that no adjustment is made to reposition the piston 11 forward in the direction of the rotor 1,
Actually, by causing the rotation of the worm 29 around the axis 29a by the one-way feeding mechanism described later,
The power screw 13 is given rotation around the axis of the worm 29 in addition to the rotation due to the swing of the arm 20, and on the other hand, when the brake is released, the power screw 13 is screwed into rotation only by the return swing of the arm 20. As a result, the return position of the piston 11 is repositioned to the rotor 1 side by an amount corresponding to (screw-out rotation) - (screw-in rotation) = Δ.

The above is the configuration of the arm swing drive mechanism, and in this embodiment, a one-way feed mechanism for rotating the worm 29 in this mechanism is provided as follows.
That is, the adjusting gear 30, which is provided so as to be able to rotate integrally with the worm shaft 29a via a clutch portion, is normally configured to perform stationary and rotational motion consistent with the worm 29 by the clutch portion in the connected state. It's getting old. An adjuster steering key 31 is engaged with the outer peripheral teeth of the adjuster steering gear 30 so that the adjuster steering gear 30 can be rotated during brake operation.

That is, the adjust key 31 is the fourth
As shown in the figure, it is assembled to a key holding member 32, and this key holding member 32 is attached to a return spring 33.
It is normally secured to a stopper 34 which also serves as a retainer, and is provided so as to move to the right in FIG. 4 when receiving the pressing force of the adjusting rod 35. Therefore, the adjusting key 3 is inserted through the key holding member 32.
1 moves to the right in FIG. 4, the adjusting gear 30 is provided to rotate clockwise in FIG. 4. Note that 36 is a hole for housing the adjuster steering key 31 and the like formed in the arm 20, and 37 is a boot.

And Asia Steingrod 35 is the third
As shown in FIG. 4, the clevis 26 is pivotally attached to a portion of the clevis 26 close to the push rod 25 side, so that when the brake is applied, the air chamber 24 is activated and the clevis 26 swings the arm 20. In this case, the adjusting rod 35 is pushed into the housing hole 36 and pulled out when the brake is released. Further, a predetermined clearance l is set between the adjusting rod 35 and the key holding member 32, which constitutes one structure of the present invention.

FIG. 5 shows an enlarged view of the engagement portion between the adjuster steering key 31 and the adjuster steering gear 30, and shows the case where the adjuster steering key 31 is moved to the right in FIGS. 4 and 5 (brake operation). Time)
When the adjuster steering gear 30 rotates clockwise as shown in the figure and moves back in the opposite direction (when the brake is released), the adjuster steering key 31 becomes free from the teeth of the adjuster steering gear 30 and rotates the adjuster. No counterclockwise rotation of the staying gear 30 in the figure will occur.

The operation based on the above configuration will be generally explained in relation to brake activation and brake release operations.

First, the non-brake (brake release) shown in the figure
When the air chamber 24 is driven to operate the brake from this state, the arm 20 is swung by the clevis 26 in the direction B in FIG.
pushed inside.

The swinging motion of the arm 20 is transmitted as rotation to the power screw 13 through the engagement portion between the worm 29 and the worm wheel 28, and the piston 11 moves forward due to the screwing rotation, and the friction pad is caused to slide along with the sliding of the caliper 4. As mentioned above, the braking force can be obtained by the pressure of one rotor of 8 and 9.

At this time, if the forward movement of the piston 11 includes a stage accompanied by elastic deformation of the caliper reaction claw portion 6, etc., the aforementioned worm shaft 29a and the clutch portion of the adjusting gear 30 are disconnected. This prevents over-adjustment, which will be discussed later.

When the brake is released, this operation occurs in complete reverse order and returns to the initial position.

The above brake operation is basic, but as the lining wear of the friction pad progresses, the amount of swing of the arm 20 increases.
When the amount of forward movement of the adjusting rod 35 exceeds l+λ, the adjusting gear 30 rotates by one tooth, and the position of meshing engagement between the worm 29 and the worm wheel 28 is changed via the worm 29. This will cause the power screw 13 to rotate accordingly.

Let me explain this. Assuming that there is no lining wear, the amount of gap between the rotor 1 and the friction pad 8 is determined by the above-mentioned play l between the key holding member 32 and the adjusting rod 35, and the approximate tooth pitch λ of the adjusting gear 30. The sum of l+λ
During the above-described brake activation and brake release operations, the azimuth steering key 31 is in the azimuth steering range from a stationary state until a braking force is generated by the swinging of the arm 20. The adjusting gear 30 only reciprocates between one pitch of teeth (range λ in FIG. 5), and the adjusting gear 30 does not rotate.

However, in reality, the wear of the linings of the friction pads 8 and 9 progresses, and the amount of swing of the arm 20 increases accordingly. Therefore, the adjuster steering key 31 rotates the teeth of the adjuster steering gear 30 by a very small amount corresponding to the increased amount, and when the brake is released, the adjuster steering gear 30 does not return to rotation, so that Staying key 31 is Asia staying gear 30
It passes over one of the teeth, engages with the next pitch, and comes to rest (the state shown by the dotted line in Figure 5).

Then, when the brake is applied again, the adjuster steering key 31 moves the adjuster steering gear 30 to the fourth position.
Rotate in the clockwise direction as shown in Figure 5. Therefore, the rotation of the adjusting gear 30 is transmitted to the worm 29 via the clutch portion, and the screwing rotation of the power screw 13, that is, the rotation that advances the piston 11, is (swinging of the arm 20) + (swinging of the worm 29). appears as the number of rotations).

On the other hand, the return and backward movement of the piston 11 (arm 20
Since only the oscillation of

After this, the amount of swing of the arm 20 gradually increases as the lining wear of the friction pad progresses, and when the adjuster staying key 31 again passes over one tooth of the adjuster staying gear 30, the above-mentioned state is reached, and eventually the adjuster staying gear The piston 11 is repositioned to the rotor 1 side while the rotation of the piston 30 is carried out minutely at a time.

From the above explanation, the basic structure of the automatic gap adjustment device according to the present invention can be understood, but in this embodiment, further measures have been taken to prevent over-adjustment of the gap, and this point will be explained below. .

In other words, the so-called over-adjustment is caused by the fact that when the friction pad is clamped by the rotor, the caliper reaction claw 6 or the like is elastically deformed, causing the piston 11 to move forward by that amount.
If this amount of piston advance is included in the adjustment operation, this is a phenomenon in which the set gap becomes too small due to the restoration of the elastically deformed portion.

Therefore, in this embodiment, the forward movement of the piston 11 accompanied by such elastic deformation is not included in the adjustment operation, and the forward movement of the piston 11 accompanied by elastic deformation is not included. Sometimes, taking advantage of the fact that the reaction force of the piston's forward movement is extremely large, the clutch portions of the adjuster steering gear 30 and the worm shaft 29a are disconnected, whereby the adjuster steering gear 30 is moved by the adjuster steering key 31. I made it so that it would be passed around.

In this way, the swinging of the arm 20 after the piston forward reaction force increases will not be involved in the adjustment, and over-adjustment can be effectively prevented.

A specific configuration for this purpose in this embodiment is a cone portion 30 formed on the adjusting gear 30.
a and the cone portion 29b of the worm shaft 29a constitute a clutch portion, and normally the worm shaft 2
The clutch portion is kept in the connected state by the disc spring 38 that presses the disc spring 9a, but when the piston forward reaction force is transmitted from the worm wheel 28 as a force in the direction C in FIG. This is achieved by disengaging the clutch portion by moving against the force.

It will be understood that the rotation of the adjuster steering gear 30 by the adjuster steering key 31 occurs in the same way because there is a reaction force not only when the brake is applied but also when the brake is released, and therefore does not adversely affect the adjustment. .

The gap indicated by δ in the figure is a gap that allows movement of the worm shaft 29a in order to disconnect the clutch portion. 39 is a disc spring 38
40 is the worm shaft 29a.
These plugs have a penetrating portion, and these plugs seal the accommodating portion for a worm or the like from the outside air.

The end of the worm shaft 29a that protrudes outside through the plug 40 is provided with a hole 29c for manual rotation of the shaft.A tool can be inserted into the hole 29c to rotate the shaft 29a and the worm. 29
By rotating the manual, the power screw 13 can be screwed out, and the position of the piston 11 can be adjusted by rotating the worm 29 while pressing and screwing it in. It is.

As described above, the automatic gap adjustment device for air disc brakes according to the present invention utilizes the increase in the amount of swing of the arm swung by the air chamber to adjust the amount of piston advance when the brake is applied as necessary. On the other hand, by setting the amount of backward movement of the piston to a certain amount, the return resting position of the piston is repositioned to the rotor side, and reliable and stable automatic gap adjustment can be obtained. Its usefulness as a product is great. That is, according to the present invention, the adjustment mechanism is such that the adjuster steering gear that rotates the worm for adjustment has teeth formed on the circular outer periphery, so that the shape of the circular member can be effectively used. It has the effect of being able to be used for. Specifically, the amount of adjustment is determined by the rotation angle of the worm, and if this angle is set small in order to increase the adjustment sensitivity, the pitch of the gear must be formed correspondingly small. In this case, as described above, the present invention uses an adjuster steering gear in which a gear is formed on the outer periphery of a circular gear, and employs a configuration in which this gear is rotated by an adjuster steering key that moves in the tangential direction of the outer periphery. Even if the amount of adjustment is set at a small pitch (that is, angle), the amount of movement of the adjusting key for adjustment can be larger compared to a configuration in which a gear is formed on the axial side of a circular member. , there is an effect that improvement in adjustment sensitivity can be achieved mechanically without difficulty.

Furthermore, according to the configuration of the present invention, there is provided a mechanism for transmitting the movement of the arm drive mechanism to an adjuster steering key as a driving member that moves an adjuster steering gear that is a driven member for adjustment, and a mechanism for transmitting the movement of the arm drive mechanism to an adjuster steering key as a driving member that moves an adjuster steering gear as a driven member for adjustment, and a mechanism in which the adjuster steering gear and the adjuster steering key are connected to each other. Another effect is that relational configurations can be easily configured. That is, in the present invention, the reciprocating motion of, for example, the clevis of the arm drive mechanism is converted into the reciprocating motion of the adjuster steering key, and by making this reciprocating motion tangential to the adjuster steering gear, rotation of the adjuster steering gear, which is a driven member, is obtained. Because of this structure, the structure for transmitting the driving force is simple and simple, and the movement of each component member is also simplified, which has the effect of providing excellent freedom in processing and designing the members.

Although this proposal is explained using an air disc brake as an example, the present invention is applied to the camshaft end of an S-cam drum brake that rotates the camshaft and expands the shoe, which corresponds to the power screw shaft of a disc brake. It will be obvious that if an automatic gap adjustment device is provided, the gap between the shoe and the drum can be kept substantially constant.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal side view of an air disc brake, and FIG.
The figure is a plan view including the same partial cross section, and Figure 3 is Figure 3A.
FIG. 4 is a partial plan cross-sectional view of FIG. 3, and FIG. 5 is a diagram showing an engaged state of the adjusting gear and the adjusting key. 1: Rotor, 2: Support, 3: Arm, 4:
Caliper, 5: Leg, 6: Leg (reaction claw),
7: Sliding support device, 8, 9: Friction pad, 10:
Cylinder, 11: Piston, 12: Thread part, 1
3: Power screw, 14: Thread portion, 15: Large diameter flange portion, 16: Power screw rear end, 1
7: Housing, 18: Cylinder, 19: Thrust bearing, 20: Arm, 21: Inner space, 2
0a: hole, 22: bracket, 23: load distribution plate, 24: air chamber, 25: push rod, 26: clevis,
27: Pivot pin, 28: Worm wheel,
29: Worm, 29a: Worm shaft (shaft), 2
9b: Cone portion, 29c: Hole portion, 30: Adjusting steering gear, 30a: Cone portion, 31: Adjusting steering key, 32: Key holding member, 33: Return spring, 34: Stopper, 35: Adjusting rod, 36 : Accommodation hole part, 37:
Boot, 38: Belleville spring, 39: Plug, 40: Plug.

Claims (1)

[Scope of Claims] 1. In an air brake having an arm drive mechanism that rotates a power screw shaft of a disc brake or an operating camshaft of a drum brake, the swing of the arm is caused by a mechanism built into the arm that is normally non-operational. A worm that is maintained in a rotating state is provided so as to be transmitted to the power screw or the actuating cam via an engagement portion with a worm wheel pivoted on the rear end of the power screw or the actuating cam, a circular adjusting gear that is coaxial with the axis of the gear and has a one-way gear on its outer periphery, and a connecting portion between the arm and the arm drive mechanism, which is capable of reciprocating the outer periphery of the adjusting gear in a substantially tangential direction; and an adjuster steering member swingably connected to the adjuster, and the adjuster steering member rotates the adjuster steering gear, which is the one-way gear, in one direction when the arm swing amount during braking exceeds a predetermined constant value. An automatic gap adjustment device for an air brake, characterized in that a one-way feed mechanism is configured to give screw rotation to the power screw or the operating cam.