JPS5842664Y2 - It's hard to tell what's going on. - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an inwardly expanding brake for a vehicle in which a brake panel is provided with a pair of brake shoes that are mutually expanded outward by the hydraulic pressure of a wheel cylinder attached to the brake panel.
Brake operation gap adjustment with an alarm device that properly adjusts the brake gap that increases due to wear of the friction lining of the brake shoe, and also issues a warning to the vehicle operator when the wear of the friction lining reaches a certain limit. The present invention relates to a device, and an object of the present invention is to provide the device, which can appropriately adjust the warning timing depending on the thickness of the brake shoe, etc., has reliable operation, and has a simple structure.

Hereinafter, one embodiment of the present invention will be explained with reference to the drawings. In Fig. 1, reference numeral 1 denotes a brake panel fixed to a stationary part (not shown) of a vehicle, and a pair of left and right brake shoes 2, 2' are arranged inside the brake panel. The upper ends of these pistons are respectively connected to the outer ends of a pair of left and right hydraulic pistons 4, 4' in a known wheel cylinder 3 mounted on the upper part of the brake panel 1, and their lower ends are also mounted on the brake panel 1. These brake shoes 22' have friction linings 2a, 2a' on their outer circumferential surfaces.
It is equipped with

A brake drum that surrounds the brake shoes 2.degree. 2' and rotates together with the wheels is not shown.

A return spring 5 is stretched between the pair of brake shoes 2, 2', and an expander 7 is interposed between them, which communicates with one of the brake shoes 2' via a known interlocking mechanism 6.

As shown in detail in FIG. 2, the dilator T has a concave groove 8 that is open at one end and engaged with the brake shoe 2 at the other closed end.
The main body is a cylinder body 9 with a piston 10 slidably fitted inside the cylinder body 9.
One end is screwed into the lock nut 18, and the screwed part is
The other end of the screw rod 11 fixed by the screw rod 11 is made to protrude outward from the open end of the cylinder body 9, and the adjusting member 12 screwed onto the screw rod 11 is rotatably supported inside the open end of the cylinder body 9.

A groove 13 is formed at the outer end of the threaded rod 11 to engage with the brake shoe 2'.

The interlocking mechanism 6 is connected to an adjusting member 12, and each time the brake shoe 2' is expanded by a certain angle, the adjusting member 12 rotates by a certain angle so as to displace the threaded rod 11 outward in the axial direction. ing.

A position sensing switch 14 is attached to the cylinder body 9, and a sensor 15 of the switch engages with the outer peripheral surface of the piston 10 in order to sense the moving position of the piston 10.

The piston 10 has a small-diameter cylindrical portion 10a and a tapered switch actuating portion 10b continuous to the left end of the small-diameter cylindrical portion 10a.
5 normally engages with the outer circumferential surface of the small diameter cylindrical portion 10a, and at this time the position sensing switch 14 is kept open.

The position sensing switch 14 is connected to a circuit connecting a power source 17 to an alarm device 16 such as a lamp installed on the instrument panel of the vehicle.

Next, the operation of this embodiment will be explained. When pressure oil is supplied into the wheel cylinder 3 as the brake pedal is depressed, the hydraulic pistons 4 and 4' are pushed outward, and the brake shoes 2 and 2' is expanded, and the respective friction linings 2 a t 2 a' are brought into pressure contact with the inner surface of a brake drum (not shown), and braking is performed in the same manner as in the conventional case.

When the wear of the friction linings 2a and 2a' increases due to braking, and the expansion angle of the brake shoes 2' due to one braking operation reaches a value, the movement is transmitted to the adjustment member 12 via the interlocking mechanism 6. , rotate it by a certain angle in a predetermined direction.

As a result, since the cylinder body 9 and the threaded rod 11 are locked with the brake shoe 2.2' and are prevented from rotating, the threaded rod 11 is displaced axially outward, and thus the dilator 7
extends slightly to compensate for wear of the friction linings 2a, 2a'.

Therefore, the braking is released and both brake shoes 2, 2'
When each friction lining 2a retreats inward due to the restoring force of the return spring 5 and is received at the bottom of each groove 8, 13 of the cylinder body 9 and threaded rod 11.

2a' and the brake drum clearance, that is, the brake operation clearance, is kept approximately constant, and this action is caused by the friction linings 2a, 2.
This process is repeated each time a' wears out.

When the wear of the friction lining 2a92a' reaches a certain limit, the large diameter part of the switch actuating part 10b of the piston 10, which moves together with the threaded rod 11, causes the sensor 15 of the position sensing switch 14 to stand by as shown by the chain line in FIG. When the position is reached and the sensor 15 is pushed up, the position sensing switch 14 is closed, activating the alarm 16 and issuing a warning to the operator of the vehicle.

Therefore, the operator can know when to replace the brake shoes 2, 2' with new parts while driving.

In addition, in such a state, the front end of the piston 10 comes into contact with the inner end of the adjustment member 12, and the threaded rod 11 cannot move outward any further, so the adjustment effect of the brake operation gap as described above is no longer possible. Stop.

In the illustrated example, the adjustment member 12 is automatically rotated by a known interlocking mechanism 6 interposed between it and one brake shoe 2', but it can be manually operated using an appropriate tool. It may also be rotated at any time.

As described above, according to the present invention, the wheel cylinder 3 and the pair of brake shoes 2, 2' which are expanded outward by the operation of the wheel cylinder 3 are attached to the brake panel 1, and the brake shoes 2, 2' are spaced between the wheel cylinder 3 and the pair of brake shoes 2, 2'. Their friction lining 2a
Dilator 1 expandable to compensate for wear at t2a'
In the internal expansion type brake equipped with a cylinder body 9, one end of which is open and the other end of which is closed to engage one brake shoe 2, the cylinder body 9 is slidably fitted into the cylinder body 9. A piston 10, a threaded rod 11 whose one end is screwed into the piston 10 and whose other end projects outward from the open end of the cylinder body 9 and engages with the other brake shoe 2'; A lock nut 18 that can fix the threaded portion with the piston 10 is screwed onto the threaded rod 11 to close the open end of the cylinder body 9, and locks the threaded rod 11 against the cylinder body 9 during rotation. The expander T is composed of an adjustment member 12 that is moved in the axial direction, and a position sensing switch 14 is attached to the cylinder body 9, which activates an external alarm 16 when activated, and a sensor 15 of the switch 14 is attached to the cylinder body 9. The sensor 15 is inserted into the cylinder body 9 and is detected by the piston 10 when the piston 10 moves axially by a predetermined amount toward the other brake shoe 2'.
Since the switch actuator 10b is provided to operate the switch, if the piston 10 is moved in the axial direction by a predetermined amount with respect to the cylinder body 9 by automatic or manual rotation of the adjustment member 12,
The switch actuating portion 10b of the piston 10 actuates the sensor 15, thereby causing the switch 14 to actuate the alarm 16.
can be activated to warn of a certain wear limit of the friction linings 'la, 2a'.

Moreover, since the switch actuating part 10b and the sensor 15 are housed and isolated in a closed space inside the cylinder body 9, it is possible to reliably prevent external dirt, etc. from adhering and accumulating on them. There is no possibility that the sensor 15 will malfunction due to accumulation, and the friction lining la
, 2a' can always be accurately warned about the wear limit.

Furthermore, even if such an alarm is issued but the driver or maintenance worker does not notice it, or even if the alarm 16 itself is malfunctioning, the amount of movement of the piston 10, that is, the extension of the expander 7 When the amount reaches a certain amount, the Rock Knight 18 or the piston 5 comes into contact with the inner end of the adjustment member 12 and the extension of the expander 7 is suppressed, so that the adjustment member 12 is automatically adjusted by rotation. In the brake of the above type, the wear compensation function of the friction lining 23t2a' by adjusting its rotation stops at the same time as the expansion device 7 stops extending, and thereafter the friction lining 2a,
As the brake 2a' wear progresses, the brake operation gap expands and changes, and this change allows the driver to sense that the expander I has reached its extension limit, and also allows the driver to manually adjust the rotation of the adjustment member 12. In the brake of the above type, the maintenance worker can also sense that the expander 7 has reached its extension limit by not being able to rotate the adjustment member 12 during the rotation operation, and therefore In any of the above-mentioned types of brakes, the driver or maintenance worker must wear the friction lining 2a.

2a/ has reached its wear limit by a means other than the alarm 16, and the time to replace the friction linings 2a, 2a' is not missed.

Further, by adjusting the respective relative screwing positions of the threaded rod 11 with respect to the piston 10 and the adjusting member 12, for example, the distance between the switch actuator 10b and the sensor 15 can be adjusted while keeping the initial length of the dilator 7 constant. By adjusting the axial distance, the limit wear amount of the friction linings 2a, 28' before the sensor 15 starts operating can be changed as appropriate, or conversely, the limit wear amount can be kept at a constant value. The initial length of the expander 4 can be expanded or contracted as needed while maintaining the setting, and as a result, it is possible to adjust the initial length of the expander 4 to suit other models of brake equipment with different thicknesses of the friction linings 2a, 2a' and spacing between the brake shoes 2, 2'. It is possible to commonly incorporate the expander 7 into the brake system, and there is no need to prepare a dedicated expander 7 for each type of brake device, thereby reducing manufacturing costs.

Furthermore, since the adjustment member 12 serves as a lid for closing the open end of the cylinder body 9 and a stopper for regulating the limit of movement of the piston 10, it can also be used as means for fixing the threaded position of the threaded rod 11 with respect to the piston 10. Coupled with the use of the lock nut 18, which has a simple structure, the overall structure can be significantly simplified, which can greatly contribute to cost reduction.

[Brief explanation of drawings]

FIG. 1 is a vertically sectional front view of the upper half of a brake equipped with the device of the present invention, and FIG. 2 is an enlarged longitudinal sectional side view of the main part of a dilator therein. 1 is the brake panel, 2.2' is the brake shoe, 2a
t2a' is the friction lining, 3 is the wheel cylinder, 7
1 is an expander, 9 is a cylinder body, 10 is a piston, 10b is a switch actuator, 14 is a position sensing switch, 15 is a sensor, 16 is an alarm, and 18 is a lock nut.

Claims (1)

[Scope of utility model registration request] A wheel cylinder 3 and a pair of brake shoes 2, 2' which are expanded outwardly by the operation of the wheel cylinder 3 are attached to the brake panel 1, and wear of the friction linings 2a, 2a' is prevented between the two brake shoes 2, 2'. In an internally expanding brake equipped with an expander 7 that can be expanded to compensate for A piston 10 is slidably fitted inside the cylinder body, and one end is screwed into the piston 10, and the other end projects outward from the open end of the cylinder body 9 and engages with the other brake shoe 2'. A lock nut 18 that can fix the threaded portion of the threaded rod 11 and the piston 10, and a lock nut 18 that is screwed onto the threaded rod 11 to close the open end of the cylinder body 9 and lock when rotating. The expander 7 is constituted by an adjustment member 12 that moves the threaded rod 11 in the axial direction with respect to the cylinder body 9, and the cylinder body 9 is equipped with a position sensing switch 14 that activates an alarm 16 on the hand when activated. At the same time, the sensor 15 of the switch 14 is thrust into the silling body 9, and when the piston 10 moves axially by a predetermined amount toward the other brake shoe 2', the sensor 15 A brake operation gap adjustment device with an alarm device for an internal expansion type brake for a vehicle, characterized in that a switch operation part 10b for operating the brake is provided.