JPS5939224Y2 - Auto track adjuster - Google Patents

Description

[Detailed description of the invention] (Technical field) This invention always maintains the gap between the brake lining of an automobile brake and the inner peripheral surface of the drum (in the case of a disc brake, both sides of the rotor) within a certain range, and This invention relates to an auto slack adjuster for maintaining good operation.

(Background Art) Automobile brakes are widely used in which a brake lining is pressed against the inner peripheral surface of a drum on both sides of a rotor, and the friction between the two brakes a wheel connected to the drum or rotor. As the number of braking increases, the brake lining wears out, the gap between it and the friction surface of the drum or rotor (brake gap) widens, and the amount of depression of the brake pedal increases.

Therefore, if this brake clearance becomes large, an adjustment must be made to reduce the brake clearance.

In the past, this gap adjustment was done manually at a factory, etc., but recently, when the brake gap widens to a certain size, the gap is automatically adjusted in conjunction with the depression of the brake pedal. Auto slack adjusters have come into use, and various mechanisms have been devised.

(Purpose of the present invention) The present invention, as an auto slack adjuster, prevents so-called over-adjustment, which causes the lining to come into sliding contact with the inner peripheral surface of the drum or the friction surface of the rotor even when not braking due to the narrowing of the gap too much. Therefore, it is an object of the present invention to provide an auto slack adjuster that can perform effective and safe gap adjustment.

(Misappropriation of the present invention) The auto slack adjuster of the present invention is alternately attached and detached in relation to the movement of the brake shoe during braking and when braking is released.

Two sets of clutch devices are provided inside a cylindrical body and a cylindrical member, and a rod and a sleeve nut whose rotation is alternately restrained by each clutch device and which are screwed together and whose overall length changes due to the relative rotation of the two. This was taken over to adjust the brake clearance.

(Embodiments of the present invention) The present invention will be described in more detail below with reference to drawings showing embodiments.

FIG. 1 shows a first embodiment of the present invention, in which the auto slack adjuster of the present invention is incorporated into a foil cylinder for a drum brake.

1 is a cylinder body with a cylinder chamber 2 formed therein, 3 is a cylindrical member fixed by press fitting or the like into the left end of the cylinder chamber 2, and 4 is a circular hole 3a bored in the end wall of the member 3. The rod 4 is a loose rod, and the front half (right side in FIG. 1) is a threaded portion 4a, and the rear end is integrally formed with a stopper 4b having an abacus-bead-shaped inclined surface 4c.

The threaded portion 4a at the tip of the rod 4 has a threaded hole 5b at the center of the sleeve nut 5, which has a conical inclined surface 5a on the outer surface of the tip.
A stopper 4b at the rear end, which is loosely screwed together, is always pressed rightward in FIG. 1 by a spring 6 via a seat plate 7.

The elasticity of the spring 6 is slightly stronger than the elasticity of a return spring (not shown) that pulls the left and right brake shoes 9.9a back toward the center.

For this reason, the inclined surface 4c of the stopper 4b is normally pressed against the inclined surface 8 formed on the inner surface of the end of the cylindrical member 3, and the rod 4 is prevented from rotating due to the frictional force between the inclined surfaces. The sleeve nut 5, which constitutes the first clutch device, is connected to the rear end (
It is rotatably engaged with a bottomed circular hole 10a coaxially drilled from the left end in Fig. 1).

The circular hole 10a has a bottom surface (right end surface) with an inclined surface 10b that matches the inclined surface 5a of the sleeve nut 5, and a stopper ring 11 fixed to the inner peripheral surface near the opening of the circular hole 10a and the rear end surface of the sleeve nut 5. A leaf spring 12 is interposed between the
A second clutch device is constructed in which the sloped surface 5a at the tip of the nut 5 is pressed against the sloped surface 10b, and normally the sleeve nut 5 is prevented from rotating within the circular hole 10a due to the frictional force between the sloped surfaces. ing.

13 is a dust boot for preventing dust, water, etc. from adhering to the sliding surface between the cylindrical body 10 and the cylinder chamber 2.

Next, the function of this auto slack adjuster will be described.

When braking, pressure oil is supplied into the cylinder chamber 2 from the oil supply hole 14 drilled in the side surface of the cylinder body 1.
Move 0 to the right.

There is a normal brake gap between the threaded portion 4a of the rod 4 and the threaded hole 5b of the sleeve nut 5 (011 to 0.2 m/m in the case of a disc brake, and slightly larger than this in the case of a drum brake).

), and when the cylindrical body 10 moves to the right, the cylindrical body 10 causes the sleeve nut 5 to follow the sleeve nut 5 to the right by the leaf spring 12 within the range of this play.

When the amount of movement of the cylindrical body 10 exceeds the amount of play between the threaded portion 4a of the rod 4 and the threaded hole 5b of the sleeve nut 5 due to wear of the brake shoes, the slope of the slope 5a of the sleeve nut 5 and the slope of the circular hole The surface 10b separates and the frictional engagement between the two surfaces is released, and along with this, the sleeve nut l-5 is pushed by the leaf spring 12, which had been compressed until now, and rotates a little within the circular hole 10a according to the threaded portion 4a. While doing so, move slightly to the right with respect to rod 4.

Therefore, the braking is released and the left and right brake shoes 9, 9
a is returned to its original position by the return spring, since the sleeve nut 5 has moved to the right compared to before the operation, the inclined surface 5a of the nut 5 and the circular hole 1 of the piston
It comes into contact with the inclined surface 10b of 0a at a position closer to the right, and the brake gap is adjusted to a constant value.

When braking with a drum brake, the brake shoes are strongly pressed against the brake drum by hydraulic pressure, so the brake shoes and drum are elastically deformed and return to their original shape when the brake is released, a phenomenon that is repeated every time the brake is applied. .

Therefore, if the brake gap adjustment mechanism is activated to hold the brake shoe in that state when the brake seat 1- is strongly pressed against the drum, this elastic deformation will tend to recover even after the brake is released. The repulsive force causes the lining of the brake shoe to remain pressed against the drum, causing a so-called dragging phenomenon, which is inconvenient and causes vapor lock.

In general, an auto slack adjuster automatically adjusts when the piston stroke of the foil cylinder that pushes the brake shoe apart using hydraulic pressure reaches a certain size, for example, when it comes to drum brakes. If this is done when the elastic deformation of the brake shoes or drum becomes large, over-adjustment may occur, resulting in a so-called dragging condition in which the brake shoes slide against the drum even when not braking.

The present invention is designed to prevent such over-adjustment from occurring.

Next, referring to FIG. 1, a state in which brake gap adjustment is performed while avoiding over-adjustment will be explained.

Pressure oil is supplied to the cylinder body 1 to forcefully push out the cylindrical body 10 from the cylinder body 1 and press the brake shoes 9°9a against the brake drum. ) means that elastic deformation occurs due to this strong hydraulic pressure, and when the brake is released? The sum of the strong repulsive force (stronger than the force of the return spring) resulting from restoration of this deformation and the return force of the return spring acts to push the cylindrical body 10 back into the cylinder body 1.

For this reason, the rod 4 is connected to the cylindrical body 10 through the sleeve nut 5.
is pressed to the left, the rod 4 moves slightly to the left against the spring 6, and the third clutch device is activated by frictional engagement between the inclined surface 4c of the rod 4 and the inclined surface 8 of the cylindrical member 3. is removed, and the rod 4 becomes freely rotatable.

At this time, the sleeve nut 5 is pushed by the cylindrical body 10, so
Since the second clutch device using the inclined surfaces 5a and 10b is in a connected state, the sleeve nut 5 does not rotate, and the rod 4, which is rotatable while being supported by the seat plate 7, is pushed by the spring 6 and the threaded portion 4a and the threaded hole 5b of the sleeve nut 5, the sleeve nut 5 relatively enters the sleeve nut 5 while rotating and corrects the overadjustment.

When the overadjustment caused by the deformation of the brake shoe and the drum is corrected in this way, the first clutch device is connected by the spring 6, and automatic brake gap adjustment is performed as described above.

In addition, in order to smoothly perform the above operation, that is, the operation of converting the force in the axial direction of the rod into the force in the rotational direction of the sleeve nut 5 by screwing the threaded portion 4a of the rod and the screw hole 5b of the sleeve nut 5. , it is effective to use a large pitch multi-thread screw for the screw in this part.

FIG. 2 shows the cylindrical body part of the second embodiment of the present invention, in which the sleeve nut 5 and the cylindrical body 10 are connected and disconnected by a friction spring 15 instead of the frictional engagement between the conical surfaces.
This was done using a second clutch device using

A coiled friction spring 15 that lightly contacts the side surface of the sleeve nut 5 is fitted onto the sleeve nut 5. One end of this friction spring is locked to the cylindrical body 10, and the other end is free.

When braking is performed when the brake gap becomes large, the rod 4 remains immobile due to the engagement of the first clutch device by the spring 6 and the inclined surfaces 4c and 8, so the sleeve nut 5, which moves to the right together with the cylindrical body 10, engages the rod. 4, the total length of the rod 4 and sleeve nut 5 is increased.

The diameter of the friction spring is increased so that the winding direction of the coil can be determined so as not to hinder the rotation of the sleeve nut 5.

Next, when the brake is released and the cylindrical body 10 is pushed back to the left by a strong repulsive force from a brake shoe, etc., the sleeve nut 5 also moves to the left, and the threaded portion of the immovable rod 4 is used as the first clutch device. Accordingly, the sleeve tries to rotate in the opposite direction to that during braking, but at this time, the friction spring 15 reduces its diameter and tightens the sleeve nut, instantly blocking its rotation.

That is, the sleeve nut 5 and the cylindrical body 10 are brought into a connected state, and the rod 4 is pushed to the left along with the cylindrical body 10 and the sleeve nut 5 moving to the left, releasing the inclined surfaces 4c and 8 and disengaging the first clutch device. .

Other structures and functions are similar to those of the first embodiment shown in FIG.

FIG. 3 shows a third embodiment of the present invention, in which the auto slack adjuster of the present invention uses a second clutch device using the friction spring 15 of FIG. 2 on the strut 16 connecting the left and right brake shoes 9, 9a. It has been incorporated.

The strut 16 is provided separately from the wheel cylinder 17, and its left and right ends are connected to brake shoes 9, 9, respectively.
A, and an adjuster mechanism incorporated in the middle adjusts the distance between the left and right brake shoes, thereby adjusting the gap between both brake shoes 9.9a and the inner circumferential surface of the drum.

In the first embodiment shown in FIG. 1, hydraulic pressure is sent to the cylinder chamber 2 to move the cylindrical body 10 to the right and push open the brake shoes 9° 9a, while pulling the rod 4 to open the inclined surface 4c.

8 is frictionally connected to integrate the functions of the foil cylinder and the auto slack adjuster, whereas in this third embodiment, the foil cylinder and the auto slack adjuster are provided separately.

The function of the auto slack adjuster is similar to that shown in FIG.

FIG. 4 shows a fourth embodiment of the present invention, in which the auto slack adjuster of the present invention is incorporated into a disc brake cylinder. A clutch device is installed.

In order to incorporate it into a disc brake, the cylindrical member 3 is made into a piston 18 which is a modification thereof, and a compression spring 1 is installed inside it.
A first device is constructed by elastically attaching a ring body 20 having an inclined surface 8 via a spring 6, and the initial tension of the parking fluke wire (acting in the direction of the arrow a in FIG. 4) is applied instead of the spring 6. The difference from the first to third embodiments is that rod 4.
The over-adjustment prevention effect by the sleeve nut 5, first and second clutch devices is the same.

(Effects of the present invention) Since the auto slack adjuster of the present invention is constructed and operates as follows, there is no need for over-adjustment, and it is a highly versatile auto slack that can be applied to various types of brakes. It is practically effective as an adjuster.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a cross-sectional side view showing the overall configuration of the first embodiment, and FIG. FIGS. 3 and 4 are vertical side views showing the overall structure of the third to fourth embodiments, respectively. 1 cylinder body, 2 cylinder chamber, 3: cylindrical member, 3a
: circular hole, 4: rod, 4a: threaded part, 4b varnish I/flange,
4c: Inclined surface, 5 Nisleeve nut, 5a: Inclined surface, 5
b: Screw hole, 6: Spring, 7: Seat plate, 8: Inclined surface, 9.
9a Nibrake shoe, 10: Cylindrical body, 10a: Circular hole,
10b: Inclined surface, 11: Stopper ring, 12: Leaf spring, 13: Dust boot, 14: Oil supply hole, 15: Friction spring, 16: Stock I, 17: Foil cylinder, 18:
Piston, 19: compression spring, 20: ring body.

Claims (1)

[Scope of utility model registration request] A bottomed circular hole 10a is bored at one end of the cylindrical body 10,
A sleeve nut 5 which is movable and rotatable in the axial direction relative to the cylindrical body 10 is installed in the circular hole 10a, and a screw hole 5b is bored in the center of the sleeve nut 5. A rod 4, which has a threaded portion 4a loosely screwed into the cylinder 5b at one end and a stopper 4b at the other end protruding from the circular hole 10a of the cylinder 10, is inserted into the cylinder 3 and attached to the cylinder member 3. The cylindrical member 3 is designed to be relatively movable and rotatable in the axial direction to a certain extent, so that when a strong force is applied to the cylindrical member 10 in the opposite direction to that during braking when the cylindrical member 10 is not braking, there is a space between the stopper 4b of the rod 4 and the cylindrical member 3. A first clutch device is provided that allows rotation of the rod 4, and a second clutch device is provided between the sleeve nut 5 and the cylindrical body 10 that allows the rotation of the sleeve nut 5 only when the cylindrical body 10 moves to the braking state position. Auto slack adjuster equipped with a clutch device.