JPS6224264Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a clutch mechanism for a camera sprocket.

The structure and operation of the conventional device will be explained with reference to FIGS. 1 to 3.

In FIG. 2, which is a partial cross-sectional view of FIG. 1 and a partially enlarged view of FIG. do. The engaging member 4 is fixed to the sprocket drive shaft 1 by a pin 5, and has a pair of grooves 4a, 4a' extending in the axial direction. The sprocket 6 is fitted and supported around the shaft 1,
It has internal teeth 6a on the inner periphery of the lower end. The intermediate member 7 is loosely fitted around the shaft 1 and has grooves 4a, 4a' and engaging portions 7a, 7a' for engaging with the internal teeth 6a. This intermediate member 7 is urged downward in the axial direction by a spring 8 applied between the member 7 and the engaging member 4, and thereby is brought into contact with the stepped portion 1a of the sprocket drive shaft 1.

On the other hand, a lever 9 is rotatably provided around a rotation shaft 9a, and when the R button 10 is pressed upward, it rotates to the left about the shaft 9a and moves the intermediate member 7 upward against the force of the spring 8. push up to At this time, the engaging portion 7
a, 7a' are disengaged from the internal teeth 6a, and the sprocket returns to a free state in which it can be rewound from the state shown in FIG.

These conventional clutch mechanisms have the following drawbacks.

FIG. 3 shows a cross section of the engaging member 4, and the grooves 4a, 4a' of the member 4 are formed at a symmetrical position with respect to the center of rotation O due to poor machining accuracy. In such a case, as shown in FIG. 3, which is a sectional view of the engaging member 4 and the intermediate member 7, when the sprocket drive shaft 1 and the engaging member 4 rotate, the intermediate member 7 becomes eccentric, and the two engaging parts 7a, Groove 4 at 7a'
engages with the side walls of a and 4a'. However, intermediate member 7
As shown in FIG. 3, the sprocket 6 and the sprocket 6 engage only at one engaging portion 7a and one internal tooth 6a. Therefore, the force transmitted from the intermediate member 7 to the sprocket 6 does not become a couple, but only one force. Therefore, a force other than the moment component of this one force acts on the sprocket drive shaft 1, and the bearings 2 and 3
increase the friction loss at That is, the efficiency of rotational force transmission deteriorates.

The object of the present invention is to obtain a sprocket clutch mechanism with good sprocket drive shaft efficiency even if the machining accuracy is somewhat poor.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

4 and 5 are views corresponding to FIG. 1 and FIG.
Corresponding codes such as 1 are attached to most items.

There is a sprocket drive shaft 21 supported by upper and lower bearings 22 and 23, and the rotational force applied to the hoisting lever 11 is applied to the hoisting gear 12, gear 13, a gear 21a etc. that meshes with the gear 13 and is integrated with the shaft 21, etc. is transmitted to the shaft 21 via. The sprocket drive shaft 21 has a pair of pins 2 integrally protruding from both sides.
5 and 25', which are axial grooves 27b and 7 of the intermediate member 27 loosely fitted around the shaft 21.
It fits loosely into b′. The intermediate member 27 also has a pair of pawls 27a, 27a' which engage internal teeth 26a, 26a' of a sprocket 26 fitted around and pivotally supported on the sprocket drive shaft 21. The pair of grooves 27b, 27b' and the pair of claws 27a, 27a' are respectively provided around the central axis of the intermediate member 27 at an offset of about 180 degrees, and
Groove 27b (or 27b') and claw 27a (or 27
a') are offset approximately 90 degrees around the central axis and spaced apart in the axial direction. Furthermore, intermediate member 2
7 is biased downward by a spring 28 applied between the member 27 and the flange portion 21b of the sprocket drive shaft 21, and is brought into contact with the pins 25, 25'. The lever 29 is rotatable around a rotation shaft 29a, and is rotated to the left by pressing the R button 30 slidably supported by the bottom force bar 14 to move the intermediate member 27 against the force of the spring 28. push upwards. At this time, the claws 27a, 2 of the intermediate member 27
7a' comes off from the inner teeth of the sprocket 26, and the sprocket 26 is in a state where it can be rewound.

The reason why this embodiment with the above configuration does not reduce the efficiency of the sprocket drive shaft even if the machining accuracy is somewhat poor will be explained below.

FIG. 5 shows claws 27a, 27a' or internal teeth 26a,
This shows a case in which, for example, only the pawl 27a' and the internal tooth 26a' come into contact with one another as a result of the machining accuracy of the tooth 26a' being somewhat poor and the tooth 26a' being provided somewhat deviated from its original position.
However, even if it is on one side, when the sprocket drive shaft 21 tries to turn left, the pin 25 and groove 27
The intermediate member 27 also tries to rotate to the left through the engagement of the inner wall of the pin 25' and the inner wall of the groove 27b', so that the intermediate member 27 rotates in the axial direction of the pins 25, 25' and the shaft 21. It tilts around an axis extending at a substantially right angle, so that both the pawl 27a and the internal tooth 26a and the pawl 27a' and the internal tooth 29a' come into contact with each other.

In such a state, as shown in FIG.
5 and 25' are applied to the intermediate member 27, and _{the torque due to this reaction force is transmitted to the sprocket drive shaft 21, but since the forces F 1 and F 1} ' form a couple, This reaction force has no components other than moment components. Furthermore, the claws 27a and 27a' are subjected to forces F ₂ ,
F ₂ ' acts, and its reaction force is applied to the sprocket 26. However, since the forces F ₂ and F ₂ ' are also a couple, no force with a component other than the moment component is applied to the sprocket 26, and therefore the sprocket drive shaft 2
This kind of force does not work in 1 either. That is, in this embodiment, the efficiency of the bearing does not decrease.

Note that the effect of the above-mentioned inclination of the intermediate member 27 is that the engagement portions 25-27b of the drive shaft 21 and the intermediate member 27,
The larger the distance in the axial direction between 25'-27b' and the engaging portions 26a-27a and 26a'-27a' of the intermediate member 27 and the sprocket 26, the larger the distance. Also,
This inclination is determined by the sprocket drive shaft 21 and the intermediate member 2.
7 (i.e., the outer diameter of the shaft 21 and the member 27
The larger the difference in the inner diameter of the When the maximum inclination is increased, the allowable amount of eccentricity of each engaging portion from the desired position can also be increased. However, this requires a large space, so there is a limit. Therefore, in this embodiment, the engagement portion between the sprocket drive shaft 21 and the intermediate member 27 and the engagement portion of the sprocket 26 on the intermediate member 27 are provided at an angle (for example, about 90 degrees) shifted from each other, and the pawls 27a,
27a' or the internal teeth 26a, 26a' at the engagement part between the sprocket drive shaft 21 and the intermediate member 27. As the shaft 21 rotates, the intermediate member 27 is rotated against the pin 2.
5, 25' can also be absorbed by sliding in the protruding direction. That is, since the eccentricity of the engaging portion is absorbed by both the inclination of the intermediate member 27 with respect to the sprocket drive shaft 21 and the sliding movement in the direction of the pins 25 and 25', the space required to increase the maximum inclination can be kept small. It will be done.

As described above, according to the present invention, the clutch mechanism of a camera sprocket can be easily realized, in which all the transmitted force is a couple, and no force other than the moment component is transmitted to the sprocket drive shaft, thereby reducing friction loss in the bearing. It can be obtained through processing.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of the conventional example, FIG. 2 is a partially enlarged view of FIG. cross section,
FIG. 5 is a partially enlarged view of the embodiment of FIG. 4. Explanation of symbols of main parts, 21... Drive shaft, 26
... Sprocket, 25-27b, 25'-27
b'...First engaging part, 26a-27a, 26a'-2
7a'...second engaging portion, 27...intermediate member, 29...
...Release member.

Claims (1)

[Claims for Utility Model Registration] A drive shaft; a sprocket rotatably supported on the drive shaft; approximately relative to the center of rotation of the drive shaft;
A first member that engages with the drive shaft at two locations offset by 180°.
An idler is provided on the drive shaft, which transmits the rotational force of the drive shaft to the sprocket through an engagement portion and a second engagement portion that engages with the sprocket at two locations shifted approximately 180 degrees with respect to the center of rotation. A camera sprocket clutch mechanism comprising a fitted intermediate member; and a release member that disengages the second engagement portion by moving the intermediate member in the axial direction of the drive shaft, wherein the first engagement and the second engaging part are angularly offset from the rotation center and are sufficiently separated in the direction of the drive shaft, and the intermediate member is engaged with the first engaging part. A mechanism characterized in that it is slidable approximately along a line connecting two locations and tiltable around a line extending approximately perpendicular to both the line and the axial direction of the drive shaft.