JPH0226093B2 - - 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 push up 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 press friction pads against the rotor. Since the piston drive mechanism is completely different from a hydraulically actuated type, it is not possible to simply apply a known mechanism, and a suitable mechanism compatible with the structure of an 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 relatively screwed in and out, and the power screw is installed so that it cannot move in the axial direction, allowing the piston to move forward and backward.
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 caused by the rear end of the power screw protruding from the caliper (piston). This is achieved by reciprocating an arm connected to extend in the radial direction from the front end (opposite to the front end that is screwed into the front end) 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 was made from this point of view, and an intermittent drive type mechanism is provided in the part that transmits the swinging motion of the arm as rotation of the power screw, so that the amount of swinging of the arm when the brake is applied is predetermined. When the amount exceeds a small certain amount, the amount of return rotation of the work screw that occurs in conjunction with the return swing of the arm when the brake is released is reduced, thereby preventing the piston from moving backward relative to the power screw. By reducing the amount of piston, it is possible to reposition the piston forward toward the rotor.

Note that such an automatic gap adjustment device can also 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 cam shaft of a drum brake, in which the swinging of the arm is controlled by a mechanism built in the arm. The power is transmitted to the power screw or actuating cam through an engagement portion between a worm which is rotated and normally maintained in a non-rotating state and a worm wheel pivoted on the rear end of the power screw or actuating cam. a circular adjusting gear which is coaxial with the axis of the worm and has a one-way gear on its outer periphery; and an arm and an arm drive mechanism, which are capable of reciprocating the outer periphery of the adjusting gear in a tangential direction; The adjuster is swingably connected to a protrusion protruding from the arm of the clevis that connects the clevis to the side opposite to the arm drive mechanism, and the reciprocating movement of the clevis reciprocates the outer peripheral part of the adjuster steering gear in the tangential direction. and a steering member, and when the arm swing amount during braking exceeds a certain value, the adjuster steering member rotates the worm through the adjuster steering gear, which is the one-way gear, when the arm returns to swing, and the power screw is rotated. Alternatively, there is provided an automatic gap adjustment device for an air brake, characterized in that a one-way feed mechanism is configured to reduce the amount of screw-in rotation of an 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 the clutch transmission section to slip, and the condition of the clutch surface can be maintained.

The present invention will be explained below 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 intermittent drive mechanism for adjustment, which will be described later, to the power screw in addition to transmitting arm swing. , a worm 29 (see FIG. 3) built into the arm 20 and normally maintained in a non-rotating state, and a worm wheel 28 (spline engagement) that is pivoted to the rear end 16 of the power screw 13 (see FIG. 3). (See Figure 3)
The swinging motion of the arm is transmitted as rotation of the power screw through the engaging portion.

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 for the arm 20 and the intermittent drive 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 swing its extending tip in the clockwise direction in FIG. 3 (direction B in the figure), the built-in worm 29 also swings in the clockwise direction in FIG. The worm wheel 28 meshing with the worm wheel 28 is also rotated, causing rotation of the rear end 16 of the power screw (the aforementioned screw rotation). At this time, the worm 29 has a shaft 29
Since the rotational force around the axis about a does not act particularly, 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 this operation is for the case where no adjustment is performed, and when adjustment is performed, the worm 29 will rotate slightly around the axis when the arm returns and swings due to the operation of the intermittent drive mechanism, as described later. The position of the meshing engagement between the worm wheel 28 and the worm 29 can be changed by rotating the worm around its axis, so that the screw rotation applied to the power screw 13 by the return swing of the arm, As a result of synergistic rotation around the worm axis by the intermittent drive device, power screw 1 is activated during adjustment.
This means that the screw rotation shown in step 3 appears less than when no adjustment is made.

The above is the configuration of the arm swing drive mechanism, and in this embodiment, an intermittent drive 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 azimuth steering key 37, which is supported by a spring 38, is engaged with the outer circumferential teeth of the azimuth steering gear 30 so as to be able to reciprocate approximately in the circumferential direction. When the adjusting rod 35 operates the brake (when the arm swings in the direction B in FIG. 3), the adjusting rod 35 moves forward in the direction of escape with respect to the teeth of the adjusting staying gear 30, and when the brake is released (the arm swings in the direction B in FIG. 3). (during the return swing), it is provided so as to move back so as to engage the teeth of the adjuster steering gear 30 and rotate it. For this reason, Asia Sting Gear 30
may be rotated by the backward movement of the adjusting key 37, and when this rotation rotates the worm shaft 29a via the clutch portion in the connected state, the meshing engagement between the worm 29 and the worm wheel 28 is caused. The position is changed, and the relationship is such that the power screw 13 is rotated by that amount.

Here, the mechanism for reciprocating the adjuster steering key 37 is to slide the adjuster rod 35 into the hole 34 of the arm 20, and leave a predetermined clearance l between the inner end of the hole and the adjuster rod 35. The outer end of the hole is pivotally connected to the tip of the clevis 26 connected to the push rod 25 of the air chamber 24 by a shaft 36, so that the arm 20 is connected to the clevis 26 when the brake is applied. When the clevis 26 swings slightly, the adjusting rod 35 is pulled out from the hole 34, and when the brake is released, it is pushed into the hole 34 and returned to the return position. has been done. Therefore, when the amount of movement of the adjusting rod 35 in pulling out and returning due to the movement of the clevis 26 exceeds the play l, the adjusting key 37 also reciprocates in the same direction. constitutes one component of the invention. Note that 39 is a retainer and 40 is a boot.

FIG. 5 shows the teeth of the adjuster steering gear 30 and the engaging portion of the adjuster steering key 37 in the above configuration, and the adjuster steering key 37 moves forward in the D direction when the brake is applied, and in the E direction when the brake is released. to return to Therefore, the amount of movement of the adjuster steering key 37 at this time is λ, which approximately corresponds to the tooth pitch of the adjuster steering gear 30.
If this occurs, press the adjuster key 37.
Due to the backward movement of the gear, the adjusting gear 30 is advanced by one tooth. Therefore, in combination with the play l between the adjusting rod 35 and the adjusting key 37, the swinging of the arm 20 when the brake is applied is reduced. increases as the lining wear of the friction pad progresses, and for this reason, when the adjustment amount of the adjustment rod 35 pulled out by the clevis 26 exceeds a predetermined amount (l + λ), the adjustment key 37 closes one tooth of the adjustment gear 30. When the brake is released, the adjuster steering gear 30 is rotated by one tooth, and the worm 29 and the worm wheel 2 are rotated as described above.
8, the relationship is such that the power screw 13 is relatively rotated due to a change in the engagement position. In other words, with one tooth feed rotation of the adjuster steering gear 30, the power screw 1
3, the amount of screw-in rotation when the brake is released is slightly smaller than the amount of screw-out rotation when the brake is applied, and the gap is automatically adjusted by moving the piston 11 forward toward the rotor 1 side and resetting the position. It will become.

After this adjustment occurs, the amount of swing of the arm 20 during the next braking operation will be reduced by the amount of the adjustment, and therefore no adjustment will occur until the lining wear of the friction pad progresses further.

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.
This is a phenomenon in which the set gap becomes too small due to the restoration of the elastically deformed portion if this amount of piston advance is included in the adjustment operation when the brake is released.

Therefore, in this embodiment, the forward movement of the piston 11 that is accompanied by such elastic deformation is not included in the adjustment operation, and specifically, the adjustment is performed in a stationary state as described above. adjuster steering key 37 for adjuster steering gear 30
Therefore, when the piston 11 moves forward with elastic deformation, the reaction force of the forward movement of the piston is also extremely large. The clutch portion 29a is in a disconnected state, so that the adjuster steering gear 30 is rotated by the adjuster steering key 37 by frictional force.

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 31 pressing 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.

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. 32 is a disc spring 31
The plug 33, which also serves as a receptacle, is a plug having a penetration part for the worm shaft 29a, and the housing part for the worm etc. is sealed off from the outside air by these plugs.

Further, the end of the worm shaft 29a that penetrates the plug 33 and projects to the outside 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 worm 29, the manual can be used to rotate the power screw 13 without causing the cone to slip.
By rotating and performing screw rotation,
It is possible to adjust the position of the piston 11.

To summarize the operations of the air disc brake configuration explained above and describe the state in which automatic clearance adjustment is performed, first, from the non-brake (brake released) state shown in the figure, to the state in which the brake is activated. When the air chamber 24 is driven, the arm 20 is moved by the clevis 26 as shown in FIG. 3B.
The adjusting rod 3
5 is pulled out from the hole 34.

This swinging motion of the arm 20 is transmitted as rotation to the workpiece 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, causing the friction pads 8, The braking force is obtained by the pressure of one rotor of 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 worm shaft 29a and the clutch portion of the adjusting gear 30 become disconnected as described above. However, the transmission of the oscillation is carried out regardless of the movement of the clutch portion.

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

Further, the above-described brake operation is caused by the arm 20 as the lining wear of the friction pad progresses.
When the amount of forward movement of the adjusting rod 35 exceeds l + λ, the adjusting gear 30 rotates by one tooth when the brake is released. means to reduce the screw rotation of the power screw when the brake is released,
Since the amount of backward movement of the piston is correspondingly smaller, the rest position of the piston is repositioned to the rotor 1 side, and the gap adjustment is completed.

By repeating this operation, the range of swing of the arm 20 is always maintained at a substantially constant amount, and the gap between the friction pad and the rotor during non-braking times is also automatically adjusted to a substantially constant amount.

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 control the amount of backward movement of the piston when the brake is released. It has the characteristic that the gap decreases as the lining wear progresses, and reliable and stable automatic gap adjustment can be obtained, making it extremely useful. That is, according to the present invention, among the adjustment mechanisms, the adjuster steering gear that rotates the worm for adjustment has teeth formed on the circular outer periphery. It has the effect of being able to be used effectively. 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 adjustment amount is set at a small pitch (angle), the amount of movement of the adjuster steering key for adjustment can be increased compared to a configuration in which a gear is formed on the axial side of a circular member. This has the effect of making it possible to improve the adjustment sensitivity mechanically and without difficulty.

Furthermore, according to the configuration of the present invention, a mechanism that transmits the movement of the arm drive mechanism to an adjuster steering key that is a driving member that moves an adjuster steering gear;
Another advantage is that the relational structure between the adjuster steering gear and the adjuster key can be easily configured. That is, in the present invention, the reciprocating motion of 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. Therefore, the configuration for transmitting the driving force is simple and simple, and the movement of each component is also simplified.
Another advantage is that there is excellent freedom in processing and designing parts.

This proposal is explained using an air disc brake as an example.The proposed automatic gap adjustment is applied to the camshaft end of an S-cam drum brake, which rotates a camshaft corresponding to the power screw shaft of a disc brake to expand the shoe. It will be clear that the provision of the device allows the gap between the shoe and the drum to 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 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 part, 15: Large diameter flange part, 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) ,
29b: Cone portion, 29c: Hole portion, 30: Asia steering gear, 30a: Cone portion, 31: Belleville spring, 32: Plug, 33: Plug, 34: Hole, 3
5: Asia Staining Rod, 36: Axis, 37:
Asia stay key, 38: spring, 39: retainer, 40: boot.

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 clevis that is capable of reciprocating the outer periphery of the adjusting gear in a tangential direction and that connects the arm and the arm drive mechanism. an adjuster steering member that is swingably connected to a protrusion projecting from the arm on a side opposite to the arm drive mechanism, and that reciprocates the outer circumferential portion of the adjuster steering gear in a tangential direction by reciprocating motion of the clevis. When the amount of arm swinging during braking exceeds a certain value, the adjuster steering member rotates the worm through the adjuster steering gear, which is the one-way gear, when the arm swings back, and the screw of the power screw or operating cam is rotated. An air brake automatic gap adjustment device characterized by comprising a one-way feed mechanism that reduces input rotation amount.