JPH0353056Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a noise prevention device for a center brake of a vehicle.

(Prior Art) A center brake that brakes a drum connected to a propeller shaft to keep a vehicle from moving is constructed, for example, as shown in FIG. 5.

A brake drum 3 is connected between the output shaft 2 of the transmission 1 and a propeller shaft (not shown).
When the brake operating force swings the lever 4 via the wire 5 and turns a cam (not shown), the brake shoe 6 opens and brakes the drum 3.

(Problem to be solved by the invention) By the way, in such a center brake, the back plate 7 which functions as a dust cover for the brake drum 3 is made of a thin steel plate, and is attached to the bearing retainer 8 of the transmission 1. Because they are coupled together, transmission of engine and transmission vibrations causes membrane vibrations, creating noise.

Therefore, the purpose of this invention is to reduce the noise generated from the back plate.

As a related technique, a sound insulating cover mounting structure has been proposed in Japanese Utility Model Application Publication No. 1099/1983.

(Means for solving the problem) Therefore, in this invention, in the center brake interposed between the output shaft of the transmission and the propeller shaft, the outer periphery of the bearing retainer of the transmission output shaft is attached to the outer periphery of the transmission case after the transmission case. The recessed space formed between the end face and the back plate of the brake drum is sealed with a sound insulating cover. In addition, this sound insulation cover supports the transmission case and the back plate via an elastic material, and the lever is inserted into a long hole formed in the part where the lever that transmits the operating force to the brake shoe passes through the sound insulation cover. A thin plate-like elastic material having a notch for sliding contact is provided.

(Function) The sound insulating cover confines the noise generated by the back plate inside and suppresses noise radiation to the outside.
Further, since the sound insulation cover itself is supported by the transmission case and the back plate via the elastic material, no noise is generated due to vibration of the sound insulation cover itself. Furthermore, even in the part of the elongated hole where the lever for operating the brake passes through the sound insulation cover, the gap between the elongated hole and the lever is covered by an elastic material with a notch that allows the lever to slide. Noise will not leak through this long hole.

(Example) In Fig. 1, 1 is a transmission, 8 is a bearing retainer of its output shaft (not shown),
3 is a brake drum connected between a propeller shaft (not shown) and the output shaft of transmission 1, 7 is a back plate as a dust cover for drum 3, and the back plate 7 is made of thin steel plate as before. As will be described later, the inner peripheral edge thereof is fixed to the end surface of the bearing retainer 8.

A sound insulating cover 11 is attached between the back plate 7 and the rear end surface 10 of the transmission case. In this case, one end of the sound insulating cover 11 is connected to the outer peripheral edge of the back plate 7, and the other end is bent inward along the case rear end surface 10 so as to abut thereon. and bearing retainer 8
The recessed space 12 formed by the outer periphery is hermetically sealed.

Then, a space 12 sealed with a sound insulating cover 11
A sound absorbing material 13 is filled inside.

Based on this configuration, the noise generated by the back plate 7 is confined inside by the sound insulating cover 11 and further absorbed by the sound absorbing material 13, so that noise radiation to the outside is reliably suppressed.

Figure 2 shows the details of the part where the lever 4 for transmitting the braking operation force to the brake shoe side passes through the sound insulation cover 11. A thin plate-like elastic member 22 with a cut 21 is attached to the elongated hole 20 so that the lever 4 can slide thereon. The lever 4 is movable along the notch 21 while deforming the elastic material 22. At this time, the notch 21 is elastically closed except for the portion through which the lever 4 passes. Therefore, noise from inside the sound insulating cover 11 will not leak through the elongated hole 20.

Figures 3 and 4 show the details of the mounting parts of the back plate 7 and the sound insulation cover 11, in which the back plate 7 is interposed with an elastic material 15 between it and the bearing retainer 8, and bolts 16 are tightened. Accordingly, the sound insulating cover 11 is attached to the back plate 7 and the rear end surface 10 of the transmission case by interposing elastic members 17 and 18, respectively, and tightening them with a belt 19. As a result, transmission of engine vibrations to the back plate 7 and the sound insulating cover 11 is also prevented by the elastic material 15.
17 and 18, an even better noise prevention effect can be obtained.

(Effects of the invention) In summary, according to this invention, the sound insulation cover is supported via an elastic material between the back plate and the rear end surface of the transmission case, and the lever that transmits the operating force penetrates the sound insulation cover. A thin plate-like elastic material with a notch that allows the lever to operate is also provided in the back plate to prevent noise from leaking from the lever penetration part, so the noise generated by the back plate is confined within the sound insulating cover and released to the outside. This results in the effect that center brake noise can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention, Figure 2 is a sectional view showing an embodiment of this invention.
The figure is a cross-sectional perspective view of the lever penetrating portion of the above embodiment;
FIG. 3 is a detailed sectional view of the mounting portion of the back plate, and FIG. 4 is a detailed sectional view of the mounting portion of the sound insulating cover. FIG. 5 is a sectional view showing a conventional technique. 1...Transmission, 2...Transmission output shaft, 3...Brake drum, 4...
Lever, 7... Back plate, 8... Bearing retainer, 10... Transmission case rear end surface, 11... Sound insulation cover, 12... Recessed space, 13... Sound absorbing material, 14, 17, 18... Elasticity Material, 20... Long hole, 21... Notch, 22...
Thin elastic material.

Claims (1)

[Scope of utility model registration request] In a center brake installed between the transmission output shaft and the propeller shaft, a recess is formed on the outer periphery of the transmission output shaft bearing retainer between the rear end surface of the transmission case and the back plate of the brake drum. The space is sealed with a sound insulation cover, and this sound insulation cover is supported through an elastic material to the transmission case and back plate, and a lever that transmits operating force to the brake shoe is formed in a portion that passes through the sound insulation cover. 1. A noise prevention device for a center brake, characterized in that a thin plate-like elastic material is provided with a notch in which the lever slides into a long hole.