JPH0538255Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention relates to a disc brake mounted on various types of traveling vehicles such as automobiles and motorcycles. The present invention relates to a mechanical disc brake for a vehicle having a structure in which a cam lever and an adjusting nut are pushed by rotation of a cam lever pulled by a brake wire.

[Prior Art] A disc brake installed as a brake for the rear wheels of an automobile uses fluid generated in a hydraulic master cylinder when the brake pedal is pressed, as disclosed in, for example, Japanese Utility Model Application Publication No. 170729/1983. A so-called parking brake type is used, which combines a hydraulic actuation mechanism that is actuated by pressure and a mechanical actuation mechanism that is actuated by pulling the handbrake lever.

Of these, the mechanical operating mechanism has an adjustment bolt and adjustment nut that engage in the axial direction of the disk and automatically adjust the braking gap between the disk rotor and the friction pads, within a piston inserted into the cylinder bore of the caliper.

A push rod is interposed between the sleeve piston, which is disposed at the bottom of the cylinder hole in frictional engagement with the rear part of the adjustment bolt, and the camshaft, which is disposed at the rear of the bottom of the cylinder hole and perpendicular to the disk shaft. The rotational force of the camshaft is transmitted as thrust to the sleeve piston by this push rod. A cam lever is pivotally attached to one end of a camshaft that projects outside of the caliper, and this cam lever and the handbrake lever are connected by a brake wire.

The cam lever side end of the brake wire is connected to a connecting pin that is inserted into a pin hole made in the cam lever. When the handbrake lever is pulled and the brake wire rotates the cam lever and camshaft, the push rod moves. The sleeve piston is pushed to advance the adjusting bolt, adjusting nut, and piston together toward the opening of the cylinder hole, and the piston presses the friction pad against the disc rotor.

The adjustment bolt that meshes with the adjustment nut is urged toward the camshaft side opposite to the above-mentioned operating direction by the elastic force of a spring compressed between the inner wall of the cylinder hole. This fills the gap between the male and female threads of the adjusting bolt and nut to prevent rattling of the adjusting bolt and nut and at the same time provide a constant operating stroke.

[The problem that the idea aims to solve]

In such a configuration, the gap between the male and female threads is set in the operating direction of the adjustment bolt, and it takes the handbrake lever until the adjustment bolt fills this gap and pushes the adjustment nut. Since this results in stroke loss, quick operability with minimal stroke loss is desired.

By the way, when the handbrake lever is pulled and operated, if the distance between the camshaft, which is the fulcrum of rotation of the cam lever, and the connecting pin, which acts as a point of action on the camshaft, that is, the rotation radius of the connecting pin is small, the lever ratio to the camshaft will change. becomes small, and the camshaft rotates relatively large, causing the sleeve piston and adjustment bolt to move significantly. Conversely, when the rotation radius of the connecting pin is large, the lever ratio to the camshaft becomes large, producing a large rotational torque on the camshaft and increasing the clamping force acting on the friction pad.

The present invention was developed in view of these circumstances, and its purpose is to:
By filling the gap between the screws in a short period of time and quickly operating the adjuster nut, the stroke loss of the handbrake lever is kept to a minimum, while a large amount of quadrup force is applied to the friction pads after initial braking. There is a particular thing.

[Means to solve the problem]

In accordance with the above-mentioned purpose, the mechanical disc brake for a vehicle of the present invention has an adjustment bolt and an adjustment nut that automatically adjust the braking gap between the disc rotor and the friction pad engaged in the axial direction of the disc in the operating part of the caliper. a camshaft disposed behind the adjusting bolt, one end of which protrudes to the outside of the action part, a pin hole is formed in a cam lever pivotally attached to one end of the camshaft, and the cam lever is inserted into the pin hole. In a mechanical disc brake for a vehicle in which a brake wire for rotating a cam lever is connected to a connecting pin, the cam lever extends with the pin hole of the cam lever tilted toward the opposite direction of the brake wire and the inner circumferential direction of the cam lever, Further, the tip thereof is formed into a long hole bent toward the inner peripheral side of the cam lever, and the inner and outer ends of the pin hole are respectively connected to a first engaging part and a second engaging part in which the connecting pin is locked. In addition, the present invention is characterized in that a biasing means such as a spring is provided for biasing the connecting pin toward the first engaging portion when the brake is not activated.

[Effect]

When not in operation, the connecting pin is located in the first engaging part of the pin hole, and when the brake wire is pulled when the brake is activated, the connecting pin acts as a point of action on the first engaging part, and rotates the cam lever with the camshaft as a fulcrum. Rotate it in the operating direction, and then rotate the camshaft.

Since this first engaging part is located on the inner circumferential side of the cam lever, which is closer to the pivot point than the second engaging part, the lever ratio to the camshaft becomes smaller, allowing the adjustment bolt to move significantly. To quickly operate an adjusting nut by quickly filling a screw gap in a nut.

Next, when the cam lever rotates further, the pin hole moves toward the brake wire and the first engaging part changes its direction, causing the connecting pin to disengage from the first engaging part. The connecting pin then slides toward the outer circumferential side on the inclined surface of the pin hole and reaches the second engaging portion, and thereafter the connecting pin pushes the second engaging portion and rotates the cam lever.

Since the connecting pin of the second engaging part is located on the outside of the cam lever, which is farther from the rotational fulcrum than the first engaging part, the lever ratio to the camshaft is large, and a large rotational torque is obtained to the camshaft, and the adjustment bolt and It acts as a large clamping force on the friction pad through the nut.

Also, when this brake operation is released, the cam lever rotates in the counter-actuation direction and returns to its initial position.
Along with this, the connecting pin is pulled back from the pin hole toward the first engaging part by the urging means, and is locked by the first engaging part.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Disc brake 1 used for the rear wheel of a car
is equipped with a parking brake that combines a hydraulic actuation mechanism 2 and a mechanical actuation mechanism 3. A bracket 5 fixed to the vehicle body on one side of the disc rotor 4 has a caliper 6 attached to a pair of sliding pins 7. , 7 so as to be movable in the axial direction of the disk.

Linings 8a are provided on both sides of the disc rotor 4.
A pair of friction pads 8, 8 consisting of a and a back plate 8b are arranged facing each other, and the action part 6a and reaction part 6b of the caliper 6, which are arranged with both the friction pads 8, 8 in between, engage in friction with the disc rotor 4. Padded 8,8
They are connected at a bridge portion 6c that straddles the two.

The action part 6a has a large diameter hole 9a and a small diameter communication hole 9.
A cylinder hole 9 is formed in the disk axial direction, and a small-tip piston 10 is fluid-tightly and movably inserted into the large-diameter hole 9a that opens toward the disk rotor 4 side. An inlet port 12 is formed in the hydraulic pressure chamber 11 defined between the bottom of the large diameter hole 9a and the piston 10, and the hydraulic pressure generated by a known hydraulic master cylinder (not shown) is transferred to this hydraulic pressure chamber 11. It is designed to be introduced into the hydraulic pressure chamber 11 through an inlet port 12.

The above-mentioned hydraulic actuation mechanism 2 includes a piston 10,
The hydraulic master cylinder is composed of a hydraulic pressure chamber 11 formed in the large diameter hole 9a and an inlet port 12, and the hydraulic pressure of the hydraulic master cylinder supplied to the hydraulic pressure chamber 11 from the inlet port 12 is transferred to the piston of the large diameter hole 9a. 10, an adjuster 13 and a sleeve piston 14 of the mechanical actuation mechanism 3, which will be described later, are integrally pushed toward the disc rotor 4 side.

The piston 10, which moves forward through the large diameter hole 9a with this supply fluid pressure, moves one friction pad 8 to the disc rotor 4.
Then, due to this reaction, the caliper 6 moves toward the acting part 6a, and the reaction part 6b
The other friction pad 8 is pressed against the other side of the disc rotor 4, and the disc rotor 4 is pressed against both friction pads 8,
8 to perform a braking action.

On the other hand, the mechanical actuation mechanism 3 is used for a parking brake that performs a braking action when the driver pulls the handbrake lever.
These include an adjuster 13 in which an adjuster bolt 15 and an adjuster nut 16 are screwed together in the disk axial direction within the cylinder hole 9, a sleeve piston 14 located at the bottom of the large diameter hole 9a, and a sleeve piston 14 located at the rear of the cylinder hole 9. It has a camshaft 17 and a push rod 18 interposed between the camshaft 17 and the sleeve piston 14.

The sleeve piston 14 has a large diameter shaft portion 14a disposed at the bottom of the large diameter hole 9a prevented from rotating by a pin 19, and a rear small diameter shaft portion 14b inserted into the communication hole 9b to move in the disk axial direction. A tapered clutch surface 14c and a small diameter shaft hole 14d are continuously formed in the large diameter shaft portion 14a.

Further, the adjustment bolt 15 has a male thread 15a at the tip thereof screwed into a female thread 16a of an adjustment nut 16 which is prevented from rotating on the piston 10 by a pin 20, and a rear end shaft 15b is connected to the shaft hole of the sleeve piston 14. 14d, and is attached by frictionally engaging the clutch surface 15d on the outer periphery of the intermediate flange 15c with the clutch surface 14c of the sleeve piston 14 by the elastic force of the spring 21.

At the rear of the communication hole 9b, a bearing hole 22 that is perpendicular to the disk shaft is provided and opens in one side wall of the operating portion 6a.
is inserted. The camshaft 17 has a bearing hole 22
A base end of a cam lever 24, which is rotatably supported by a bearing 23 inside and bent into a crank shape at one end protruding from the bearing hole 22, is attached to a washer 25.
and is pivoted with a nut 26.

A coil-shaped return spring 27 is disposed around the outer periphery of the nut 26 to bias the cam lever 24 in the non-braking direction (clockwise in FIG. 1), and the cam lever 24 is connected to a handbrake lever inside the vehicle. The brake wire 28 is connected to the wire end 29
and are connected via a connecting pin 30.

A pin hole 31 for connecting the brake wire 28 is provided on the tip side of the cam lever 24. This pin hole 31 extends obliquely from the outer circumferential side of the cam lever 24 toward the anti-brake wire direction and the inner circumferential direction, and has a bent tip toward the inner circumferential side of the cam lever. The inner and outer ends of the pin hole 31 are
They are respectively a first engaging portion 31a and a second engaging portion 31b. Both engaging parts 31a and 31b are such that the distance from the rotation fulcrum O of the camshaft 17 and the cam lever 24 is l ₁ at the first engaging part 31a, and at l 1 at the second engaging part 31b. l ₂ longer than l ₁
It is becoming.

The brake wire 28 holds the tip side of the cam lever 24 between two forked pieces 29a, 29a of a wire end 29 fixed to the end, and these two forked pieces 29
A connecting pin 30 is inserted through the pin hole 31 and the connecting pin 30 to be connected to the cam lever 24. When inactive, the connecting pin 30 is pulled by the pulling force of the spring 32 stretched between it and the return spring 27.
It is biased by the first engaging portion 31a of the pin hole 31.

The present embodiment is constructed as described above, and when the camshaft 17 and the cam lever 24 are in an inactive state in which the handbrake lever inside the vehicle is not pulled or operated, the locking protrusion 24a of the cam lever 24 is held by the return spring 27. , a connecting pin 30 that is biased to a position where it comes into contact with a locking pin 33 protruding from the action portion 6a and biased by a spring 32;
is also engaged with the first engaging portion 31a of the pin hole 31 (both are shown in solid line positions in FIG. 1).

In addition, the adjustment bolt 15 in the cylinder hole 9
is due to the elastic force of the spring 21, and the clutch surface 1
5d is the clutch surface 14 of the sleeve piston 14
The adjustment bolt 15 is elastically pushed toward the bottom of the cylinder hole 9 so as to frictionally engage with the adjustment nut 16, and the gap between the male thread 15a and the female thread 16a of the adjustment nut 16 is set in the operating direction of the adjustment bolt 15.

Next, when the brake wire 28 is pulled by pulling the handbrake lever, the connecting pin 30 acts as a point of action on the first engaging portion 29a, and the cam lever 24 and the camshaft 17 act as a rotation fulcrum. It rotates counterclockwise in FIG. 1 about O.

The first engaging portion 31a that the connecting pin 30 engages with is
Since the distance l ₁ from the rotation fulcrum O is shorter than the distance l ₂ of the second engaging portion 31b, the lever ratio with respect to the camshaft 17 becomes small. As a result, the amount of rotation of the camshaft 17 increases, moving the sleeve piston 14 and the adjusting bolt 15 by a large amount, filling the screw gap between the adjusting bolt 15 and the nut 16 in a short time, and tightening the adjusting nut 16.
operate quickly.

Then, when the cam lever 24 further rotates, the pin hole 31 moves toward the brake wire, and the first
As the engaging portion 31a changes its direction, the connecting pin 30 disengages from the first engaging portion 31a and connects the inclined surface 31c of the pin hole 31 to the cam lever 24.
The connecting pin 30 then pushes the second engaging portion 31b and rotates the cam lever 24.

On the other hand, the rotational force transmitted to the camshaft 17 is converted into a thrust force by the push rod 18, which moves the piston 10 together with the sleeve piston 14, adjustment bolt 15, and adjustment nut 16 toward the disc rotor 4, and moves both friction pads together. 8, 8 are pressed against the disc rotor 4 in the same manner as in the hydraulic pressure operation described above to effect a braking operation.

When the lining 8a of the friction pad 8 wears out due to repeated braking operations, and the braking gap between the disc rotor 4 and the lining 8a widens beyond the set value,
During hydraulic or mechanical operation, the frictional engagement between the clutch surface 15d of the adjusting bolt 15 and the clutch surface 14c of the sleeve piston 14 is disengaged.
The adjustment bolt 15 is paid out from the adjustment nut 16, and restricts the retraction limit of the advanced piston 10, thereby compensating for wear by the braking gap.

The connecting pin 30 that has engaged with the second engaging portion is located on the outer circumferential side of the cam lever 24 that is further away from the rotational fulcrum O than the first engaging portion 31a, so that the camshaft 17
The lever ratio to the camshaft 17 is increased, and a large rotational torque is obtained for the camshaft 17. Therefore, after the initial braking after filling the thread gap between the adjusting bolt 15 and the nut 16, this torque acts as a large clamping force on the friction pads 8, 8.

Furthermore, when this brake operation is released, the camshaft 17 and the cam lever 24 are rotated in the counteracting direction by the biasing force of the return spring 27 and returned to the initial position, and the connecting pin 30 is also
2, the second engaging portion 31b is pulled back to the first engaging portion 31a.

In this way, in this embodiment, the adjusting bolt 15
Since the screw gap of the nut 16 is filled in a short time and the adjusting nut 16 is quickly raised, the loss stroke of the handbrake lever can be kept extremely small. Further, after the initial braking, the friction pads 8, 8 are clamped with a large clamping force, so that reliable braking can be performed with a light pulling operation. Furthermore, by moving the connecting pin 30, a good operating feeling of the handbrake lever can be obtained.

Note that the length, inclination angle, and distance between the pivot point and the first engaging portion of the pin hole formed in the cam lever can be changed as appropriate depending on design conditions.

In addition, in the above embodiment, the disc brake for the rear wheel combined with a hydraulic type was explained, but the present invention
It is applicable to purely mechanical disc brakes.

[Effect of idea]

In the mechanical disc brake for a vehicle of the present invention, the pin hole of the cam lever is inclined to extend toward the opposite direction of the brake wire and the inner circumferential direction of the cam lever, and the tip thereof is further bent toward the inner circumferential side of the cam lever. The pin hole is formed into an elongated hole, and the inner and outer ends of the pin hole are used as a first engaging part and a second engaging part to which the connecting pin is locked, respectively, and the connecting pin is held in the second engaging part when the brake is not activated. 1. Since a biasing means such as a spring is provided to bias the engaging part, in the initial stage of braking, the screw gap between the adjustment bolt and nut is filled in a short time and the adjustment nut is activated quickly, thereby reducing stroke loss of the handbrake lever. After the initial braking, the lever ratio of the cam lever to the camshaft increases, clamping the friction pad with a large clamping force, allowing reliable braking with a light pulling operation. Furthermore, a natural and good operating feeling of the handbrake lever can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a sectional front view of essential parts of a disc brake, FIG. 2 is a sectional plan view of the disc brake, and FIG. 3 is a sectional view taken from FIG. 1. 1... Disc brake, 3... Mechanical operating mechanism, 6... Caliper, 8... Friction pad, 9...
Cylinder hole, 9a... Large diameter hole, 9b... Communication hole,
10... Piston, 13... Adjuster, 14...
... Sleeve piston, 15 ... Adjustment bolt, 15a ... Male thread, 16 ... Adjustment nut, 16a ... Female thread, 17 ... Camshaft,
18... Push rod, 24... Cam lever,
27... Return spring, 28... Brake wire, 29... Wire end, 30... Connection pin, 31... Pin hole, 31a... First engaging portion, 3
1b...second engaging portion, 31c...slanted surface, 32...
...Spring serving as the biasing means of the present invention, O... Rotating fulcrum of the camshaft 17 and cam lever 24, l ₁
...Distance between the rotation fulcrum O and the first engaging part, l ₂ ...Distance between the rotation fulcrum O and the second engagement part.

Claims (1)

[Scope of utility model registration request] An adjustment bolt and an adjustment nut that automatically adjust the braking gap between the disc rotor and the friction pad are provided in the action part of the caliper and mesh with each other in the axial direction of the disc, and one end of the camshaft is disposed behind the adjustment bolt. A mechanical type in which a pin hole is formed in the cam lever which is pivoted to one end of the camshaft, and a brake wire that rotates the cam lever is connected to a connecting pin that is inserted through the pin hole. In a disc brake for a vehicle, the pin hole of the cam lever is formed into a long hole that extends with the cam lever inclined toward the direction opposite to the brake wire and the inner circumferential direction of the cam lever, and further bends its tip toward the inner circumferential side of the cam lever. and forming an inner end and an outer end of the pin hole as a first engaging part and a second engaging part to which the connecting pin is locked, respectively,
A mechanical disc brake for a vehicle, characterized in that a biasing means such as a spring is provided for biasing the connecting pin toward the first engaging portion when the brake is not activated.