JPH0418173B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Field of Application The present invention relates to a disc brake device with a parking mechanism that can mechanically press a piston of a brake caliper, and in particular, to are slidably fitted to define a hydraulic chamber connected to the brake master cylinder, and the brake caliper supports a camshaft rotated by a parking lever, and a brake gap disposed in the hydraulic chamber is formed. The camshaft is connected to the inner end wall of the piston through an automatic adjustment device, and the automatic brake gap adjustment device includes a non-rotatable fixed clutch body that is pushed in the axial direction by rotation of the camshaft; an adjusting bolt integrally having a movable clutch body that frictionally engages with the fixed clutch body by the hydraulic pressure of the hydraulic chamber; and the adjusting bolt is screwed onto the adjusting bolt via a quick screw and abuts on the inner end wall of the piston so as to be able to separate. An adjustment nut, an overadjustment prevention spring that urges the adjustment nut in a direction of contact with the piston, and a rotation prevention means provided between the piston and the adjustment nut to prevent relative rotation between the two. related to things.

(2) Prior Art Conventionally, the rotation preventing means in this type of disc brake device has been provided on one of the opposing surfaces of the piston and the adjusting nut, as shown in, for example, Japanese Utility Model Application Publication No. 57-104026. It consists of a radial slit and a protrusion provided on the other side and engaged with the slit.

(3) Problems to be solved by the invention In the conventional structure described above, the slit needs to be formed deeply in order to engage the slit and the protrusion deeply enough to reliably prevent the piston and adjustment nut from rotating each other. In that case, the strength of the piston or the adjusting nut may be impaired due to the formation of the slit. Furthermore, due to the abutment between the inner end of the piston and the adjusting nut, and the engagement between the slit and the protrusion, the space facing the piston and the adjusting nut is cut off from the hydraulic chamber side. Due to this, it is difficult to smoothly release the bubbles generated in the hydraulic oil in the space, and furthermore, when trying to fill the empty hydraulic chamber with hydraulic oil during the assembly of a disc brake device, etc. However, there are drawbacks such as the fact that air existing in the space before the hydraulic oil is filled is trapped and it is difficult to vent the air.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple and effective disc brake device that eliminates these drawbacks.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides that the rotation preventing means is formed in a rectangular recess provided in the inner end wall of the piston and in the adjusting nut. and a rectangular flange that is integrally formed with the rectangular recess and loosely fitted into the rectangular recess, and is characterized in that the front surface of the rectangular flange is provided with an air relief groove substantially orthogonal to the sides of the rectangular shape.

(2) Action If the camshaft is rotated in the operating direction using the parking lever, the piston can be operated forward via the automatic brake gap adjustment device.

In this case, a large rotational torque acts on the adjustment nut due to the thrust load applied to the adjustment bolt from the camshaft, but the rotation of the adjustment nut is firmly prevented by the piston through the square flange and square recess that fit together. Therefore, the thrust load can be reliably transmitted to the piston via the adjustment nut.

Even if air bubbles are generated in the hydraulic oil in the space facing the piston and the adjustment nut due to overheating of the hydraulic oil due to braking, the air bubbles move to the outer circumferential side of the adjustment nut through the air relief groove. From there, it is further discharged to the reservoir tank side of the master cylinder through a hydraulic chamber and hydraulic piping. In addition, when an empty hydraulic chamber is filled with hydraulic oil during the assembly process of a disc brake device, the air in the space moves to the outer circumference of the adjustment nut through the air release groove, and from there the air bubbles It is discharged to the outside in the same manner as above or from the air discharge hole of the hydraulic chamber. In particular, since the air relief groove runs through the shortest distance substantially perpendicular to the sides of the rectangular flange, the bubbles or air move quickly and are easily discharged to the outside.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. These friction pads 2, 2' are slidably supported in the axial direction of the brake disc 1 on guide rails of a bracket 3 fixed to the vehicle body. Further, a brake caliper 4 is connected to the bracket 3 so as to be slidable in the axial direction of the brake disc 1, straddling both the friction pads 2, 2'.

The brake caliper 4 includes a first pinching arm 4a facing the back surface of the first friction pad 2, and a second pinching arm 4b contacting the back surface of the second friction pad 2'. The first pinching arm 4a has a cylinder 5 opening on its inner surface, into which a piston 6 that abuts the back surface of the first friction pad 2 is slidably fitted via a seal member 8. A hydraulic chamber 7 defined within the cylinder 5 by the piston 6 is communicated via a hydraulic conduit P with an output port of a master cylinder (not shown).

A camshaft 9 extending in a direction perpendicular to the axis of the piston 6 is rotatably supported at the outer end of the first pinching arm 4a of the brake caliper 4 via a needle bearing 10. It is connected to the piston 6 via an automatic brake gap adjustment device 11 disposed within the cylinder 5 .

In FIG. 2, a parking lever 12 is attached to the outer end of the camshaft 9 that projects outside the brake caliper 4, and is fixed with a nut 13. The parking lever 12 has a brake wire 14 connected to a parking operator (not shown), and a brake wire 14 connected to the parking lever 12.
A return spring 15 that urges the lever 2 in the backward direction is connected to the lever 12, and the backward limit of the lever 12 is regulated by a stopper pin 16 implanted in the first pinch arm 4a.

Referring again to FIG. 1, the automatic brake gap adjustment device 11 will be described in detail. A small cylinder 17 is connected to the rear wall of the cylinder 5, and a relay piston 1 is connected to the camshaft 9 via a push rod 18.
9 is slid onto this small cylinder 17 via a seal member 20. A fixed clutch body 21 facing the hydraulic chamber 7 is integrally connected to the inner end of the relay piston 19, and a fixed clutch body 21 is installed on the back side of the relay piston 19 so that the fixed clutch body 21 can move together with the piston 19 without rotating. The detent pin 23 is slid into the detent hole 24 of the first pinching arm 4a.

The fixed clutch body 21 has a frusto-conical clutch surface 21a on its front surface, and further has a small cylinder 25 opening at the center of the clutch surface 21a. A conical movable clutch body 22, which is integrated with an adjustment bolt 26, is engaged with the clutch surface 21a, and a small piston 27, which is also integrated with an adjustment bolt 26, is slid onto the small cylinder 25 via a seal member 28, and is movable. A clutch spring 29 presses the movable clutch body 22 against the clutch surface 21a.
and a retainer 30 secured to the inner circumferential wall of the hydraulic chamber 7.
The movable clutch body 22 is compressed between the clutch spring 29 and the movable clutch body 22.
A ball bearing 31 is interposed to facilitate smooth rotation. Further, the movable clutch body 22 is provided with a communication hole 32 that communicates between its front and rear end surfaces.

The adjustment bolt 26 is disposed on the axis of the piston 6 and is screwed into an adjustment nut 33 that abuts the inner end wall of the piston 6 via a quick screw 34. The adjustment nut 33 is, for example, a rectangular square flange 3.
5 at the front end (see FIGS. 3A, 3B, and 5), and this square flange 35 is connected to a similarly square square recess 36 formed on the inner end wall of the piston 6.
(See Figures 4A and 4B). In order to press and hold the square flange 35 against the bottom surface of the square recess 36, an over-adjustment prevention spring 37 is applied.
is compressed between the rectangular flange 35 and a retainer 38 secured to the inner circumferential wall of the piston 6. Adjusting nut 33 is thus prevented from rotating relative to piston 6.

The piston 6 also engages with the back plate of the first friction pad 2, which is slidably supported by the bracket 3, to prevent it from rotating around its own axis.

Front surfaces 35a of square flanges 35 that abut each other
And the bottom surface 36a of the rectangular recess 36 is connected to the adjustment nut 3.
The adjusting nut 33 is formed as a spherical surface with its center on the third side, and is adapted to provide the adjusting nut 33 with a self-centering effect on the piston 6.

Further, on the front surface 35a of the square flange 35, there are a plurality of air relief grooves 3 that are substantially orthogonal to each side of the square.
9, 39...... are provided.

Next, to explain the operation of this embodiment, in order to perform braking, if a brake master cylinder (not shown) is operated and its output hydraulic pressure is supplied to the hydraulic chamber 7 of the first pinching arm 4a, the piston receives the hydraulic pressure. 6 advances while applying shearing deformation to the seal member 8, and the first
The friction pad 2 is pressed against one side of the brake disc 1, and the reaction force moves the brake pad 4 in the opposite direction to the movement of the piston 6, and the second pinching arm 4b pushes the second friction pad 2' against the other side of the brake disc 1. Press it against the In this way a braking force can be applied to the brake disc 1 and thus to the wheels.

During this braking, the hydraulic pressure in the hydraulic chamber 7 is controlled by the adjusting nut 3.
3, no thrust is exerted on the movable clutch body 22 because it acts equally on both end surfaces thereof, but a thrust corresponding to the value obtained by multiplying the cross-sectional area of the small piston 27 by the above-mentioned oil level is applied to the movable clutch body 22. This hydraulic thrust and the elastic force of the clutch spring 29 are applied toward the clutch surface 21a, and the movable clutch body 22
The frictional engagement force between the fixed clutch body 21 and the fixed clutch body 21 is determined.

By the way, in a normal braking state, the hydraulic pressure in the hydraulic chamber 7 is relatively low, so the movable clutch body 22
Since the frictional engagement force between the piston 6 and the fixed clutch body 21 is relatively small, when the piston 6 moves forward due to wear of the friction pads 2 and 2', the adjusting nut 33 is moved by the elastic force of the over-adjustment prevention spring 37. 6 and separates the movable clutch body 22 from the clutch surface 21a via the adjusting bolt 26 against the hydraulic thrust and the elastic force of the clutch spring 29. The movable clutch body 22 has a clutch surface 21
When separated from a, the adjusting nut 3 becomes unrotatable due to the hydraulic thrust and the elastic force of the clutch spring 29.
3, moves toward the clutch surface 21a and engages with the clutch surface 21a again. In this way, a self-adjusting effect takes place which compensates for the wear of the friction pads 2, 2'.

Here, when the pressure inside the hydraulic chamber 7 is reduced to release the brake, the piston 6 retreats due to the deformation restoring force of the seal member 8, but the retreating force is absorbed by the adjusting nut 33,
Via the adjusting bolt 26, the movable clutch body 22 is actuated as a thrust towards the clutch surface 21a, so that the movable clutch body 22 is moved against the fixed clutch body 2.
1, the adjustment bolt 26 is prevented from rotating. Therefore, the piston 6 can only move backward by a stroke corresponding to the backlash of the threaded portion of the adjustment nut 33 and adjustment bolt 26.
As a result, an appropriate gap is provided between the friction pads 2, 2' and the brake disk 1 to accommodate the above-mentioned backlash.

Further, when strong braking is performed, the automatic adjustment action as described above is performed until the hydraulic pressure in the hydraulic chamber 7 rises to a predetermined value that causes elastic deformation in the brake caliper 4. When the hydraulic pressure exceeds the predetermined value, the hydraulic thrust on the movable clutch body 22 increases to maintain the movable clutch body 22 in frictional engagement with the clutch surface 21a, so that the adjusting bolt 26 cannot rotate. Therefore, since the adjusting nut 33, which is originally non-rotatable, is fastened on the adjusting bolt 26, if the piston 6 moves further due to the elastic deformation of the brake caliper 4, it will resist the elastic force of the over-adjustment prevention spring 37. As a result, the piston 6 and the adjusting nut 33 are forced to be separated from each other in the axial direction. In this way, the automatic adjustment action is stopped and over-adjustment is prevented.

When parking, if the brake wire 14 is pulled by operating a parking operator (not shown) and the parking lever 12 is rotated against the force of the return spring 15, the camshaft 9 is rotated in the operating direction, and the push rod 18 and Brake gap automatic adjustment device 11
The piston 6 can be moved forward through the hydraulic pressure chamber 6, and therefore a braking force can be applied to the brake disc 1 in the same way as when hydraulic pressure is supplied to the hydraulic chamber 6.

In this case, the camshaft 9 is connected to the piston 6 without any play via the push rod 18 and the automatic brake clearance adjustment device 11, and as described above, the automatic brake clearance adjustment device 11 allows the camshaft 9 to connect with the brake disc 1 and the friction pads 2, 2. Since a certain gap is provided between the parking lever 12 and the parking lever 12, braking can be performed reliably by always rotating the parking lever 12 at a substantially constant angle. Further, due to the thrust load applied from the camshaft 9 to the adjustment bolt 26, a large rotational torque acts on the adjustment nut 33, but the rotation of the adjustment nut 33 is caused by the rotation of the adjustment nut 33 via the square flange 35 and the square recess 36 that fit together. Since it is firmly blocked by the piston 6, the thrust load can be reliably transmitted to the piston 6 via the adjustment nut 33.

Even if air bubbles are generated in the hydraulic oil in the space facing the piston 6 and the adjusting nut 33 due to overheating of the hydraulic oil due to braking, the air bubbles will pass through the air relief groove 39 to the outer peripheral side of the adjusting nut 33. From there, it is further discharged to the reservoir tank side of the master cylinder through the hydraulic chamber 7 and hydraulic piping. Furthermore, when filling the empty hydraulic chamber 7 with hydraulic oil in the process of assembling the disc brake device, etc., the air in the space moves through the air relief groove 39 to the outer circumferential side of the adjustment nut 33, and from there It is discharged to the outside in the same way as air bubbles or from the air discharge hole of the hydraulic chamber 7. In particular, since each air relief groove 39 passes through the shortest distance substantially orthogonal to the side of the rectangular flange 35, the bubbles or air move quickly and are easily discharged to the outside.

C. Effects of the Invention As described above, according to the present invention, the rotation preventing means for preventing mutual rotation of the piston and the adjusting nut is provided.
Since it is composed of a rectangular recess provided on the inner end wall of the piston and a rectangular flange that is formed integrally with the adjustment nut and is loosely fitted into the rectangular recess, the piston can be mounted without sacrificing the strength of either the piston or the adjustment nut. , it is possible to firmly prevent relative rotation between the two, and therefore, the thrust load caused by the operation of the parking lever can be reliably transmitted to the piston via the automatic adjustment device, and parking braking can be performed.

In addition, an air relief groove is provided on the front surface of the square flange, which is approximately perpendicular to the sides of the square. Air bubbles generated in the hydraulic oil in the space and air existing in the same space before the hydraulic oil is filled into the hydraulic chamber can be quickly moved to the outer periphery of the adjustment nut. Discharge to the outside of the brake caliper can be quickly and easily increased. Moreover, since the air relief groove does not need to function as a locking recess for preventing rotation between the piston and the adjusting nut, there is no need to form the groove particularly deep to ensure its function. Even with the special provision of the groove, there is no problem of a decrease in the strength of the adjusting nut.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a longitudinal sectional front view of the whole, FIG. 2 is a front view of a part thereof, FIG. 3A is a front view of an adjustment nut, and FIG. 3B is a front view of a part of the adjustment nut. 4A is a back view of the piston, FIG. 4B is a sectional view taken along the line - 4A in FIG. 4, and FIG. 5 is a perspective view of the adjustment nut. 4... Brake caliper, 4a, 4b... First and second pinch arms, 5... Cylinder, 6... Piston, 7... Hydraulic chamber, 9... Camshaft, 11... Brake gap automatic adjustment device , 12... Parking lever, 18... Push rod, 19... Relay piston, 21... Fixed clutch body, 21a... Clutch surface, 22... Movable clutch body, 25... Small cylinder, 26... Adjustment bolt, 27... Small piston, 29... Clutch spring, 33... Adjusting nut, 34... Quick screw, 35... Square flange, 3
5a...Front surface, 36...Square recess, 36a...Bottom surface, 37...Overadjustment prevention spring, 39...
...Air release groove.

Claims (1)

[Claims] 1 A piston 6 is slidably fitted into the brake caliper 4 to define a hydraulic chamber 7 connected to the brake master cylinder, and the brake caliper 4 supports a camshaft 9 rotated by a parking lever 12. The camshaft 9 is connected to the inner end wall of the piston 6 via an automatic brake gap adjustment device 11 disposed in the hydraulic chamber 7. Non-rotatable fixed clutch body 21 that is pushed in the axial direction by rotation
, an adjusting bolt 26 integrally having a movable clutch body 22 that frictionally engages with the fixed clutch body 21 by the hydraulic pressure of the hydraulic chamber 7;
an adjustment nut 33 that is screwed together via a quick screw 34 and abuts the inner end wall of the piston 6 in a separable manner; and an overadjustment prevention spring that biases the adjustment nut 33 in the direction of contact with the piston 6. 37, and a rotation prevention means provided between the piston 6 and the adjusting nut 33 to prevent relative rotation between the two, in which the rotation prevention means is provided between the piston 6 and the adjustment nut 33.
a square recess 36 provided on the inner end wall of the adjustment nut 33; and a square recess 36 formed integrally with the adjustment nut 33.
A disc brake device with a parking mechanism, comprising a rectangular flange 35 which is loosely fitted into the flange 35, and an air relief groove 39 is provided on the front surface of the rectangular flange 35, which is substantially perpendicular to the sides of the rectangular shape.