JPH0343471Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a one-way clutch mechanism used in equipment such as cameras.

(Prior art) In cameras that have a built-in motor and use the motor's driving force to wind the film, charge the shutter, etc., power is transmitted only in one direction in order to distribute the motor's driving force appropriately. A one-way clutch is often required. In particular, in systems equipped with a film autoloading function (hereinafter referred to as AL), in which the sprocket only feeds the film during film loading, and then winds the film onto the spool, a one-way clutch is installed in the sprocket drive system. A mechanism is essential.
A one-way clutch used for this purpose requires the following conditions:

Small and space-efficient (actually, an outer diameter of φ6 to φ8 is required).

There is no slip in the driving direction, and a relatively large transmission force (several kgcm) can be obtained.

There should be almost no frictional force on the free side (if there is resistance on the free side, the sprocket will not become free, which will not only make winding heavier but also lead to perforation damage).

Manufacturing costs are low.

Various types of one-way clutch mechanisms are known to meet the above requirements, but among them, a so-called windmill type as shown in Figure 1 is often used due to its reliability of operation.

In FIG. 1, a drive cam 1 is coaxially fixed to a drive shaft 2 so that it can rotate together with the drive shaft 2. Reference numeral 3 denotes a drive ring which can rotate relatively coaxially with the drive shaft 2 and the drive cam 1, and the drive shaft 2 and the drive ring 3 each have a fitted outer diameter portion 2.
a and the fitting inner diameter portion 3a are fitted into each other. Reference numeral 4 denotes rollers, one each being arranged in three gaps between the drive cam 1 and the drive ring 3, and each roller is pressed against the cam surface of the drive cam 1 and the inner wall surface of the drive ring 3 by a preload spring 5. are in contact. A spring cover 6 is arranged to prevent the roller 4 and preload spring 5 from falling off. Now, when the drive shaft 2 and drive cam 1 rotate counterclockwise (in the direction of the arrow), the rollers 4 bite between the cam surface of the drive cam 1 and the inner wall surface of the drive ring 3, and the drive ring 3 Rotates integrally with 1. Further, when the drive shaft 2 and the drive cam 1 rotate clockwise, the rollers 4 slip, and no power is transmitted between the drive cam 1 and the drive ring 3. In this configuration, the preload spring 5 is an essential component for the one-way mechanism to operate accurately. That is, when the drive cam 1 is rotated in the direction of the arrow, the reason why the rollers 4 bite between the drive cam 1 and the drive ring 3 is due to the slight relative rotation between the drive cam 1 and the drive ring 3. Therefore, at the start of driving, unless all three rollers 4 are in contact with the drive cam 1 and the drive ring 3 in the same way, the three rollers will not bite at the same time, and only one roller 4 will bite first. Once this is done, the drive cam 1 and the drive ring 3 will no longer rotate relative to each other, so the remaining rollers 4 will not bite. Even in this state, power is transmitted, but since the transmitted force is concentrated on one roller 4, the drive ring 3 may be deformed, or unreasonable lateral pressure may be applied to the fitting parts 2a, 3a. The rotation is not smooth. Furthermore, if one roller 4 cannot absorb the transmission force, it will cause slippage, and after a while the remaining rollers will bite. These problems can be solved to some extent by incorporating the preload spring 5, but it is necessary to control the variation in the preload force at three locations, the part shape, surface roughness, etc., and the problem of high cost has also arisen. was desired.

(Purpose of the invention) The present invention was made in order to solve the above-mentioned conventional problems, and its purpose is to provide a one-way clutch mechanism that is small, highly reliable, and inexpensive.

In order to achieve the above object, the present invention is designed so that the drive ring and the drive cam can be moved relative to each other in the eccentric direction within a range where the maximum diameter part of the cam surface does not come into contact with the inner diameter surface of the drive ring. It features a one-way clutch mechanism that eliminates the preload spring required in the past.

(Example) Next, a one-way mechanism according to the present invention will be explained.
FIG. 2 shows a one-way mechanism according to the present invention. In the figure, reference numeral 8 denotes a drive cam having a cam surface 8a whose outer diameter is gently displaced, and is fixed to the drive shaft 9 so as to be able to rotate integrally therewith. Reference numeral 10 denotes a drive ring, which is sandwiched between the drive cam 8 and the flange portion 9a of the drive shaft 9, is rotatable around the drive shaft 9, and has an inner diameter that is Eccentricity is possible because a gap e (e'+e') is provided between the two. The gap e is set within a range where the maximum diameter portion of the cam surface 8a of the drive cam 8 does not come into contact with the inner diameter surface of the drive ring 10 even if the drive ring 10 is eccentric to the maximum. A ball 11 is disposed in the gap between the drive cam 8 and the drive ring 10. 12 is a coupler for transmission, which is coaxial with the drive shaft 9 or can be rotated independently, and includes a notch 12a and a drive ring 10.
The engagement protrusion 10a of the drive ring 10 is engaged with the engagement protrusion 10a to transmit the rotational force of the drive ring 10. In this embodiment, since there is no preload spring, the ball 11 moves freely within the gap between the cam surface 8a of the drive cam 8 and the drive ring 10. Therefore, the position at which the ball 11 waits with respect to the drive cam 8 is not constant. but,
Since the drive ring 10 has no restriction in the radial direction with respect to the drive shaft 9, the position of the drive ring 10 is always determined only via the three balls 11. In this state, when the drive cam 8 is rotated counterclockwise, if all three balls 11 are in contact with the drive cam 8 and the drive ring 10, they immediately bite and power is transmitted. At this time, since there is no preload spring, all three balls 11 are not necessarily in contact with the drive cam 8 and the drive ring 10. Even in this case, when any one of the balls 11 comes into contact, the drive cam 8 first applies side pressure to the drive via the ball 11 at that part. Accordingly, the drive ring 10 moves eccentrically in that direction, so that the remaining opposing balls 11 come into contact with the drive cam 8 and the drive ring 10. That is, if at least one of the three balls 11 is not in contact at the start of driving, the drive cam 8 moves in the direction in which the three balls 11 come into contact and bite. Therefore, the rotational force is not transmitted to the drive ring 10 until even one ball 11 is bitten, and when all three balls 11 are bitten,
It will transmit rotational force. Therefore, stress is not concentrated on any one of the three balls 11, and since the three balls 11 are always bitten at the same time, there is almost no slippage. Furthermore, since the drive ring 10 moves in a direction that equalizes the biting force of the balls 11 at three locations to some extent, the dimensional accuracy of the cam shape of the cam surface 8a of the drive cam 8 is not required to be highly accurate, and it is difficult to manufacture parts. You can also measure cost reduction.
Furthermore, since there is no need to incorporate a preload spring during assembly, assembly is easy.

Furthermore, the gap e set between the drive shaft 9 and the drive ring 10 is such that the drive ring 1 is
Even if the drive ring 10 is eccentric to the maximum, the maximum diameter of the cam surface 8a of the cam 8 is set in a range where it does not touch the inner diameter surface of the ring 10, so the drive ring 10 will always keep the ball in contact with the drive cam 8. Since the position is determined only through the ball 11, all three balls are connected to the drive cam 8 through contact with the ball 11, and problems such as stress concentration and slipping do not occur.

(Effect of the invention) As explained above, the invention allows the drive ring and the drive cam to be moved relative to each other in the eccentric direction within the range where the maximum diameter part of the cam surface does not come into contact with the inner diameter surface of the drive ring. Because it is supported so that the preload spring that is conventionally required can be removed, the overall size can be easily achieved, the cost can be reduced and the number of assembly steps can be reduced, and stress can be concentrated in one place. Therefore, it is possible to provide a one-way clutch mechanism that can prevent slippage and prevent unauthorized slippage.

[Brief explanation of the drawing]

FIG. 1 shows a conventional one-way clutch mechanism, with FIG. 1a being a perspective view and FIG. 1b being a sectional view.
Fig. 2 shows a one-way clutch mechanism according to an embodiment of the present invention, Fig. 2a is a perspective view, and Fig. 2b is a sectional view. 8... Drive cam, 10... Drive ring, e'...
Gap, 11...Ball.

Claims (1)

[Scope of utility model registration request] A drive cam having cam surfaces formed at multiple locations on its outer peripheral surface, a drive ring that surrounds the outer periphery of the cam surface and has an inner diameter larger than the maximum diameter of the cam surface, and a cam surface of the drive cam and the drive ring. In a one-way clutch mechanism in which a rotating member such as a ball or roller is disposed between the drive ring and the drive cam, the drive ring and the drive cam are arranged within a range where the maximum diameter part of the cam surface does not come into contact with the inner diameter surface of the drive ring. A one-way clutch mechanism is characterized in that the clutch is supported so as to be relatively movable in an eccentric direction.