JPS62140263A - Felt clutch mechanism - Google Patents

Abstract

PURPOSE:To stably drive a tape without a torque stick and torque fluctuation by forming the surface of a groove part facing the felt member of a clutch at an appropriate surface coarseness by etching. CONSTITUTION:The felt member 5 is stuck to the clutch 3, and thereon the clutch 6 is energized by a spring 8. And a torque generating groove part 6b is formed on the surface abutting on the felt member 5 of the clutch 6, and at an appropriate surface coarseness by chemical etching or a sand blast. In this constitution, power inputted to the clutch 3 being an input gear is transmitted to the clutch 6 through the felt member 5 and the groove part 6b. At that time, since the surface of the groove part has an appropriate coarseness, the tape can be stably driven without the torque stick and torque fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a felt clutch mechanism for generating torque in video tape recorders and the like, and particularly to a felt clutch mechanism suitable for torque stick and torque fluctuation countermeasures.

[Conventional technology]

A conventional felt clutch mechanism has a structure in which a felt member is interposed between two clutches. In addition, related to this type of mechanism is the Japanese Patent Publication No. 51-47605.
No. 55-29871.

[Problem that the invention seeks to solve]

In the conventional felt clutch mechanism, no particular consideration was given to the contact surface of the clutch with the seven-rut member. In general, the surface roughness of the groove of a torque-generating component (clutch) that comes into contact with a felt member is determined by the cutting tool and cutting conditions in the case of cutting, and is determined by the precision of the mold and molding conditions in the case of integrally molded products. Note that Figures 1, 175 and 176 are characteristic diagrams showing the friction coefficient and torque in these conventional cases.

Therefore, a stable torque mechanism for hunting has been used because it is technically impossible to deal with minute torque fluctuations. In this case, there was a problem of high cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a felt clutch mechanism for generating torque in a video tape recorder or the like that is stable and free from torque stick and torque fluctuations.

[Means for solving problems]

When torque is generated, the friction coefficient of the contact surface between the groove of the torque generating part and the felt member changes from static friction to dynamic friction. The roughness has been finished to reduce changes in the coefficient of friction.

[Effect]

In other words, we made sure that the torque and friction that occurs when rotating very slowly (less than 1 revolution per second) remains constant.

) [Example] An example of the present invention will be described with reference to FIGS. 1 and 2. 1st
The figure is a sectional view of essential parts of the felt clutch mechanism. In the figure, 1 indicates a chassis board, and a shaft 2 is installed on the board. The shaft 2 is provided with a groove 2α.

The clutch (L) 3 and the clutch presser 4 rotate together through press-fit engagement, and their height is regulated by a washer 9.

Clutch +r+ 3K has a felt member 5 attached. The clutch (O) 6 and the spring presser 7 are the clutch (O)
) The clutch (0) 6 and the spring 8° spring holder 7 rotate together, with the height being regulated by the outer periphery convex portion 4cL of the clutch holder 4 due to the biasing force of the spring 8. Clutch (0) B has a torque generating groove 6k formed on its surface facing the felt member 5. The groove surface is formed with appropriate roughness and irregularities by chemical etching, sandblasting, or other methods. (Second
figure·). Torque is determined by felt member 5 and clutch (0) 6
It has a predetermined torque value due to the biasing force of a spring 8, which is a compression spring. Torque is generated when power is transmitted to the input gear, the clutch 3, through the felt member 5 due to frictional transmission between the felt member 6b and the groove 6 of the clutch (0) 6, and then to the output gear, the clutch 06. During power transmission, the friction coefficient between the felt member 5 and the groove 6 changes from static friction utL to dynamic friction u+ as shown in FIG.
The groove surface of b is chemically etched or 3.

Since the appropriate roughness is formed by a method such as sandblasting, there is little change in the friction coefficient and it is effective in eliminating torque stick and torque fluctuation as shown in FIG. 4.

〔Effect of the invention〕

According to the present invention, the groove surface of the torque generating component and the groove surface of the contact surface of the felt member are formed with appropriate roughness by chemical etching, sandblasting, etc., thereby reducing torque stick and torque fluctuation. This eliminates the need for stable torque, eliminates performance deterioration such as image shaking, and enables tape drive suitable for video tape recorders. It is of great industrial value because torque management parts, which could only be made by other companies, can be made at a low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing an embodiment of the present invention, FIG. 2 is a detailed view of the torque generating groove surface of clutch 0 in FIG. 1, and FIG.
Figure 4 shows the relationship between the friction coefficient and speed, Figure 4 shows the torque change, Figure 5 shows the relationship between the friction coefficient and speed of the conventional method, and Figure 6 shows the torque change of the conventional method. It is. 1... Chassis board 2... Shaft 3... Clutch L 4... Clutch retainer 5... Felt member 6... Clutch 0 7... Spring retainer 8... Spring 9... washer

Claims (1)

[Claims] It consists of a torque-generating spring, a member pressed by the spring, a felt member that comes into contact with the member, and a member that adhesively fixes the felt member.The surface that comes into contact with the felt member has an appropriate surface roughness (unevenness). A felt clutch mechanism characterized by a structure that reduces torque fluctuation.