JPS6347531A - Structure of disk brake - Google Patents

Abstract

PURPOSE:To obtain a highly accurate roundness by forming a piston driving oil chamber with the inner peripheral face of a brake case and the outer peripheral face of a piston member, and eliminating the machining of a groove. CONSTITUTION:A first inner peripheral face 6a and a second inner peripheral face 6b having a larger diameter than that of the first inner peripheral face 6a are concentrically provided while forming a stepped part in a brake case 6. And, a stepped outer peripheral face is provided on a piston member 13, and is oil sealedly fitted into the brake case 6, and cut-out parts provided in several places are engaged with engaging pins 12. And, an operating pressure oil is fed into an annular piston driving oil chamber S which is formed in between the stepped part between the first and second inner peripheral faces 6a, 6b of the brake case 6 and the piston member 13. Accordingly, the machining of a groove can be eliminated, obtaining a highly accurate roundness.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is configured such that a ring-shaped piston member arranged concentrically with a brake disc is driven and shifted to the brake disc pressing side by hydraulic pressure. Regarding disc brake structure.

[Conventional technology]

As shown in Fig. 2, the disc brake structure using the ring-shaped piston member as described above has an annular groove in the ring-shaped support seat (16) between the brake case (6) and the transmission case (1). At the same time, the annular leg of the piston member (13) is inserted into the annular groove, and pressure oil is sent into the annular oil chamber formed by the piston member (13) and the annular groove to form the Vinton member (13). ) is configured to press the brake disc (10) by shifting the drive.

[Problem that the invention seeks to solve]

With the above structure, the annular oil chamber formed by the legs of the piston member and the annular groove must be kept in a sufficiently oil-tight state. The inner and outer circumferential surfaces of the annular groove must be machined so that their roundness and concentricity are sufficiently accurate.

The leg part of the piston member is almost the same as machining the inner and outer surfaces of a cylinder, and high-precision machining is relatively easy, but high-precision groove machining has low work efficiency and tends to be expensive. Met.

SUMMARY OF THE INVENTION An object of the present invention is to provide a disc brake structure in which high oil tightness of an oil chamber for piston member drive shifting can be obtained relatively easily and at low cost.

[Means for solving problems]

The feature of the present invention is that, in an improved disc brake structure, a first inner circumferential surface and a second inner circumferential surface having different diameters are formed in a stepped and concentric manner on the inner wall surface of a brake case into which a brake disc is fitted. At the same time, the piston member is slidably fitted in an oil-tight manner over the first and second inner circumferential surfaces, and the piston is fitted between the stepped portion of the first and second inner circumferential surfaces and the piston member. The reason is that a driving oil chamber is formed, and its functions and effects are as follows.

[For production]

When configured as described above, the oil tightness of the piston driving oil chamber is determined by the accuracy of both contact sliding surfaces between the first and second inner circumferential surfaces of the brake case and the outer circumferential surface of the piston member, that is, the accuracy of the first and second inner circumferential surfaces of the brake case and the outer circumferential surface of the piston member. It is based on the circularity of the first and second inner circumferential surfaces, the circularity of the outer circumferential surface of the piston member, and the concentricity of each inner and outer circumferential surface.

The inner and outer circumferential surfaces described above are substantially the same as the machining of a normal cylinder, and it is relatively easy to obtain high precision in both roundness and concentricity compared to the case where groove machining is performed.

〔Effect of the invention〕

As described above, since the grooved part is eliminated and the oil chamber for driving the screws 1 to 1 is formed between the inner peripheral surface of the brake case and the outer peripheral surface of the piston member, the structure is relatively easy to process and the piston is driven. It has become possible to reduce manufacturing costs while maintaining the oil tightness of the oil chamber.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

Figure 1 is a longitudinal sectional front view of the vicinity of the rear wheel differential mechanism (2) of the transmission case (1) of a work vehicle such as an agricultural tractor. ) are arranged, and differential wheels (3) protrude left and right from the rear wheel differential mechanism (2). This rear wheel differential mechanism (2
) is supported via the case support (14),
The case support (14) supports the mission case (1) inside the recess formed on the outer surface (la) of the mission case (1).
1).

A differential lock shift member (4) is spline-fitted to the differential wheel (3), and a spring (1) is fitted to the differential wheel (3).
The shift member (4), which is biased toward the cutting side by the shifter (5), is slid in the axial direction by the shifter (5), and the differential case (2
Perform differential lock operation by engaging a).

A brake case (
6), the axle case (7) is connected, and the differential wheel (3)
The power is transmitted to the axle (9) via the planetary reduction mechanism (8) and drives the rear wheels (not shown).

Next, to explain in detail the wet type disc brake structure housed in the brake case (6), as shown in the figure, a brake disc (10) is spline-fitted to the differential shaft (3). This brake disc (10)
A ring-shaped plate (11) is inserted into the brake case (6) with a ring-shaped plate (11) sandwiched therebetween. and,
(11) Provide notches at multiple locations on the outer periphery, engage the locking pins (12) located at multiple locations within the brake case (6), and insert the differential wheels (3) and As the brake disc (10) rotates, the plate (
11) is structured so that it does not rotate together.

Next, the brake disc (10) and the plate (1
1) toward the mission case (1) side. The brake case (6) has a first inner circumferential surface (6a) and a second inner circumferential surface (6a) with a larger diameter. The inner circumferential surface (6b) is provided concentrically to form a stepped portion. And this first and second inner circumferential surfaces (6a)
, (6b), the piston member (13) is provided with a step-shaped outer circumferential surface that slides into contact with the brake case (6), and is fitted into the brake case (6) in an oil-tight manner. The provided notch is engaged with the locking pin (12).

Then, the first and second inner circumferential surfaces (
6a) and (6b) and the piston member (1
3) an annular piston drive oil chamber (S
) into the piston member (13).
by slidingly driving the brake disc (10) and plate (11) to the outer surface (1a) of the transmission case (1).
It applies pressure to brake.

[Brief explanation of drawings]

The drawings show an embodiment of the disc brake structure according to the present invention, in which FIG. 1 is a longitudinal sectional front view of the vicinity of the rear wheel differential mechanism, and FIG. 2 is a longitudinal sectional front view of the vicinity of the rear wheel differential mechanism in a conventional structure. (6)... Brake case, (6a)...
...First inner circumferential surface, (6b)...Second inner circumferential surface, (
10)...Brake disc, (13)...
... Piston member, (S) ... Piston drive oil chamber.

Claims (1)

[Claims] The disc brake structure is configured such that a ring-shaped piston member (13) arranged concentrically with the brake disc (10) is driven and shifted by hydraulic pressure toward the pressing side of the brake disc (10), A first inner circumferential surface (6a) and a second inner circumferential surface (6b) having different diameters are formed in a stepped and concentric manner on the inner wall surface of the brake case (6) into which the brake disc (10) is fitted. At the same time, the piston member (13) is attached to the first and second inner circumferential surfaces (6a).
, (6b), and is slidably fitted in an oil-tight manner over the first and second parts.
A disc brake structure in which a piston driving oil chamber (S) is formed between the stepped portion of the second inner peripheral surfaces (6a) and (6b) and the piston member (13).