JPS5986723A - Disc brake equipped with parking brake mechanism - Google Patents

Abstract

PURPOSE:To keep a parking brake in satisfactory state even when thermal contraction occurs due to the cooling of a high temperature brake disc by a structure wherein a play permitting a relative rotational interlocking in a coupling part between a rotating shaft and an actuating lever, both of which consists of the interlocking mechanism of camshaft and the like, in the range of a predetermined rotational angle is provided. CONSTITUTION:Parking brake is performed as follows: when an actuating lever 19 and a camshaft 14, which is integral with the actuating lever 19, are rotated by actuating a hand brake lever, an auxiliary piston 5 is moved rightward through a strut 17 and a push rod 12 and at the same time a main piston 3 is pushed through a protruded part 6 in order to press a brake pad 29 against a disc (not shown). In this case, a play with a certain fixed rotational angle alpha in provided in a coupling part between the camshaft 14 and the lever 19. Said play consists in forming a non-circular cross-sectional form on the camshaft 14 while a similar non-circular slot of the fitting hole on the lever 19 and at the same time providing sectoral gaps 37 and 37 at the corners of the slot. Due to said play, the thermal contraction of the disc and the like is rendered to be able to absorb.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to a disc brake incorporating a parking brake mechanism.

(b) Did you incorporate a conventional parking brake mechanism? 2. Description of the Related Art Disc brakes, so-called built-in parking brake mechanisms, have been known for a long time.

Figure 1 shows part 1+MI, and this disc brake has a main piston 3 inside a cylinder 2 provided in a caliper 1.
The inside of the main piston 3 has a tabular surface 4. The auxiliary piston 5 is inserted concentrically into the main piston 3.

A protrusion 11 (0) is provided on the outer periphery of the auxiliary screw I/N 5 that contacts the tapered surface 4 of the month IJ record, and a thrust bearing 'r is applied to the protrusion 6, and between the retainer 8 and the bearing r. The bearing r is pressed against the protrusion with a wave washer 9 interposed.

Further, on the inner circumferential surface of the bore 10 provided in the auxiliary piston 5, a multi-thread screw 1 that engages with a multi-thread screw 11 with a large lead is provided.
3, and the bushing rod 12 is screwed to the auxiliary piston 5.

The rear end of the bushing rod 12 faces the camshaft 14 inserted into the caliper 1 in a direction perpendicular thereto, and a recess 15 provided in the end face of the bushing rod 12 and a cam surface 16 of the camshaft 14 are connected to each other. Strut 1 between
7 is intervening.

The above-mentioned camshaft 14 is rotatably supported by a needle bearing 1B which has an open portion where the strut 17 passes, and an operating lever 1 is attached to the protruding end of the camshaft 14.
It combines 9.

In addition, a push-back spring 20 is inserted around the C bushing rod 12 inside the cylinder 2, and a spring holder that supports one end of the push-back spring 20 is used as a key plate 21.
A holder 23 is attached to the inner periphery of the cylinder 2 by a snap ring 24, and the bushing rod 12 is non-rotatably engaged with the stepped portion 22 of the bushing rod 12, and the other end thereof is engaged and supported.

In addition, as shown in Fig. 1, 2-J, 29 is a brake pad, 3O+; I piston seal, 31 is a fixed part 4A,
33 is a support bracket for the brake wire.

The disc brake described above rotates the actuating lever 19 and the camshaft 14 integrated therewith by operating the brake lever, thereby pushing the butt rod 12 through the strut 17.

By pushing the bushing rod 12, the auxiliary piston 5
pushes the main piston 3 through the protrusion 6 and the main piston 3
The brake/mud 29 is brought into pressure contact with a disc (not shown).

The caliper 1 is pulled inward by this [JE contact force, and the caliper 1 is brought into H-contact with the outer brake pad 29' or disc.
t, braking force is applied.

Further, when the handbrake lever is returned to its original position, the bushing rod 12 is pushed back by the spring force of the spring 20. At this time, the auxiliary piston 5 and the main piston 3 are retracted together by the retracting action of the piston seal 30.

Incidentally, during normal service brake operation, the hydraulic pressure acting within the main piston 3 and the cylinder 2 causes f'F.

(C) Problems to be Solved by the Invention In the above disc brake device, the garrison brake is operated when the disc or brake pads 29, 29' are at a high temperature;
If left as is, the T-isk or brake pads 29, 29', which had been thermally expanded at high temperatures, will gradually contract as they cool. Therefore, the brake pad 29,
The pressing force against the disc 29' is reduced, and there is a risk that the automatic vehicle will start moving by itself, for example, when the vehicle is parked on a slope.

(2) Means for Solving the Problems In order to solve the above problems, the present invention provides a method for applying relative rotational movement within a predetermined rotational angle range to the connecting portion between the rotating shaft of an interlocking mechanism such as a camshaft and the operating lever. Provide permissible play,
Use one end of the coil spring fitted to the rotating shaft as the operating lever, etc.

The ends are respectively engaged with the rotating shaft, and the spring force at the time of engagement is set to a predetermined value, and the rotational torque of the rotating shaft is less than the predetermined value.
When the rotary shaft and the actuating lever rotate together through the coil spring, and the rotational torque of the rotary shaft exceeds the predetermined value, the spring is twisted and the lever and the rotary shaft rotate.
It is configured to perform relative rotation within a predetermined rotation angle range.

With the above configuration, the handbrake lever is exposed and the rotation axis of the interlocking mechanism is rotated once through the operating lever.
After 1jh, the bushing rod is pushed out and presses the brake pad against the disc, but when the rotational torque of the rotating shaft gradually increases and exceeds a predetermined value, the actuating lever compresses the spring and increases the play described above in 11 with respect to the rotating shaft. Rotate within the range. As a result, a spring force in one direction acts on the rotating shaft to push out the bushing rod, so even if the disc or brake pad heat shrinks due to cooling, the shrinkage plastic will be absorbed by the above spring force. . In other words, the low pressing force F is compensated for by the spring force.

This is applied to a disc brake with a city brake mechanism, and Figures 2 and 3 show the structure of the improved part.

FIG. 2 shows the mounting portion of the above-mentioned operating lever 519, in which the operating lever 19 is attached to the protruding end of the camshaft 14, and the bracket 33 of the brake wire 34 is attached near the operating lever 19 with the mounting bolt 35. Shown is installed.

Further, the lever 19 is engaged with a coil spring 36 wound around the camshaft 14 for lever return, and the other end thereof is engaged with the mounting bolt 35. Further, FIG. 3 shows that the above-mentioned operating lever 19 is constructed by stacking two metal plates.

The above structure is that of the prior art, but in the case of the present invention, play of a constant rotational angle α is created at the joint portion of the camshaft 14 and the lever 19 as shown in Fig. In other words, in the conventional case, the fitting part between the camshaft 14 and the lever 19 is formed into a non-circular shape jl<I+'I
In the present invention, the cross section of the camshaft 14) has a linear shape. (4
As shown in the figure, the lever has a non-circular shape 119 consisting of opposing flat surfaces and opposing circular arc surfaces in both river directions.
The fitting hole 19 is inserted into the sector-shaped cavity 37 above the centrally symmetrical core of the non-circular F1-1, which has the same shape as the L-marked camshaft I.14.
．． 37, and the relative rotation of the cam/shaft 14 and lever 19 causes the camshaft 14 to move into the gap 37.
．． It is now possible to enter a-r.

Additionally, an auxiliary coil spring 348 is provided around the camshaft 14, and as shown in FIG.
'Q is engaged with the lever 19, and the other end is engaged with the camshaft 14. The spring force of this coil spring 3tJ is determined as follows.

That is, the relationship between the stroke S of the operating lever 19 and the pressing force F of the piston 3 is shown in No. 7c1.1.

As can be seen from this figure, at the beginning of the operation of the actuating lever 19, while the pressing force is smaller than the predetermined value F2, the actuating lever 19 and the camshaft 14 rotate together via the spring 38. When the pressing force reaches a predetermined value F2, the spring 38 is bent and the actuating lever 19 is moved toward the camshaft 1.
4 by an allowable rotation angle, and during this time the pressing force increases as the spring 38 comes out to a shallow depth determined by the spring constant and deflection of the spring 38. When the lever 19 and camshaft 14 rotate once by the allowable rotation angle (that is, when the pressing force reaches F3), the lever 19 and camshaft 14 rotate together again, and the pressing force increases in accordance with the lever rotation torque (see Figure 7-1)-C. ).

In addition, in FIG. 7, the dotted line b-e indicates the auxiliary spring 3.
8 is the case when pressed. In addition, l in the figure is the amount of play generated by thermal contraction, and in the case of a device equipped with an auxiliary spring of 3 days as in the present invention, the piston pressing force when a gap l occurs is Fa, but this What is not possible is Fb, and Fl3 (Fa) is Fb (
Fp.

Fa ) Fp (Fl) is l11 @ ability limit value) Teal.

Further, in the above embodiment, the lever 19 and the camshaft 1
The one bamboo strip between 4 and 4 is formed by providing a gap 37. The camshaft 14 may be formed into a C shape by cutting out a centrally symmetrical corner portion of the camshaft 14.

(F) Effect Since the present invention has the above-described configuration, when the parking brake is applied with the disc or brake pad heated to a high temperature, even if the disc or brake pad thermally shrinks due to cooling, the spring of the auxiliary spring Since a pushing force can be applied to the bushing rod through the H rotation axis of the interlocking groove of the C camshaft or the like, gaps caused by heat shrinkage can be absorbed and a predetermined braking force can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a sectional view of an improved part according to the present invention, FIG. 3 is a sectional view of FIG. 2, and FIGS. FIG. 47 is a graph showing the relationship between lever stroke S and piston pressing force F. DESCRIPTION OF SYMBOLS 1... Caliper, 2... Cylinder, 3... Main piston, 5... Auxiliary 111+ piston, 12... Bushing rod, 14... Camshaft, 11... Strut, 19... Made by “Auxiliary lever, 3r...Gap, 3B
... Sode suke spring. Patent applicant: Sumitomo Electric Industries, Ltd. Agent: Kama 1) Bun 2

Claims (1)

[Claims] A parking brake machine +R (;, +28 In the disc brake, a play is provided at the connecting portion between the rotating shaft of the interlocking mechanism and the operating lever to allow relative rotational movement within a predetermined rotational angle range, and one end of the coil spring fitted to the disposed rotating shaft is actuated. Engage the other jilifs on the L/bar and the rotating shaft respectively, set the spring force at the time of engagement to be a predetermined value, and when the rotational torque of the 49-axis is greater than the predetermined value F-, the rotating shaft and The operating lever rotates together through a coil spring of ε, and when the rotational torque of the rotating shaft exceeds the predetermined value, the spring is twisted and the lever and rotating shaft rotate relative to each other within a predetermined rotation angle range. A disc brake with a one-way brake mechanism that features a cylindrical surface.