JPH09101550A - Driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cover a gap formed between another member and a rotary shaft with a sleeve part and to prevent the entering of the end part of a torsion spring into the gap by inserting the sleeve part formed in another member between the rotary shaft and the torsion spring. SOLUTION: In the driving device provided with the rotary shaft 12 freely rotatably held by another member 11 on one end in an axial direction and the torsion spring 13 which is attached to the outer periphery of the rotary shaft 12 and restrained by another member 11 on one end and by the rotary shaft 12 on the other end, to energize the rotary shaft 12 in a rotational direction, another member 11 is provided with the sleeve part 11d inserted between the rotary shaft 12 and the torsion spring 13. In other words, the sleeve part 11d for covering the gap formed between another member 11 and the end part of the rotary shaft 12 is provided to prevent the end part of the torsion spring 13 arranged on the outer periphery of the sleeve part 11d from entering into the gap. Further, the length in the axial direction of the sleeve part 11d is about one-half of the length L of the torsion spring 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for transmitting a rotational driving force generated by a torsion spring.

[0002]

2. Description of the Related Art The above driving device is widely used for various power transmission mechanisms such as a shutter mechanism of a camera.
FIG. 2 shows an example of the driving device. In this figure, reference numeral 1 is a base plate, and the base plate 1 has fitting holes 1a and 1b.
Are formed on the same core. A locking rib 1c is formed near the fitting hole 1a in the upper portion of the base plate 1.

Reference numeral 2 is a rotary shaft, and both ends (upper and lower ends) in the axial direction.
By fitting the fitting shaft portions 2a and 2b formed in the fitting holes into the fitting holes 1a and 1b of the base plate 1, the base plate 1 is rotatably held. A gear portion 2c having an outer diameter larger than the outer diameter of the intermediate portion is formed on the lower portion of the rotary shaft 2. Further, a ring-shaped protrusion is formed at an intermediate position in the radial direction on the upper surface of the gear portion 2c, and a groove 2d is formed between the protrusion and the outer peripheral surface of the intermediate portion of the rotary shaft 2. Further, a part of the protrusion is cut out to form a spring locking portion 2e.

Reference numeral 3 is a torsion spring, and the coil-shaped portion 3c is arranged on the outer periphery of the axially intermediate portion of the rotary shaft 2. At one end (upper end) and the other end (lower end) of the coil-shaped portion 3c, hook portions 3a extending outward in the radial direction,
3b are formed, the upper hook portion 3a is locked to the locking rib 1c, and the lower hook portion 3b is a spring locking portion 2.
It is locked to e.

Therefore, when the torsion springs 3 attached to the outer circumference of the rotary shaft 2 are incorporated into the main plate 1 in a torsionally deformed state, the elastic force generated in the torsion springs 3 causes the rotary shaft 2 to rotate in the reverse direction. Rotation torque is generated. This rotational torque is transmitted to a gear or the like (not shown) that meshes with the gear portion 2c.

[0006]

However, in such a drive unit, if there is a gap between the main plate 1 and the upper end surface of the rotary shaft 2 as shown in FIG. 2, the torsion spring 3 is present in this gap. There is a problem in that the upper end of the shaft may bite and hinder the smooth rotation of the rotary shaft 2.

When the coil-shaped portion 3c is twisted and deformed, the inner periphery of the coil-shaped portion 3c and the outer periphery of the rotary shaft 2 often come into contact with each other. As a result, the driving force (loss) of the rotary shaft 2 may fluctuate significantly, and the operation of the rotary shaft 2 may become unstable.

Accordingly, a first object of the present invention is to provide a drive device capable of preventing the biting of the torsion spring. A second object of the present invention is to provide a drive device that suppresses fluctuations in the driving force due to friction between the torsion spring and the rotating shaft, etc., and enables stable rotation operation.

[0009]

In order to achieve the above object, in the first invention of the present application, a rotary shaft having at least one axial end rotatably held by a ground member and an outer periphery of the rotary shaft are attached. And a torsion spring that has one end locked to the ground member and the other end locked to the rotating shaft to bias the rotating shaft in the rotation direction. A sleeve portion is provided between the spring and the torsion spring. That is, a sleeve portion is provided to cover a gap formed between the ground member and the end portion of the rotary shaft so that the end portion of the torsion spring arranged on the outer circumference of the sleeve portion does not bite into the gap.

Further, in the second aspect of the present invention, the axial length of the sleeve portion is set to be approximately 1/2 of the axial length of the torsion spring.

That is, the fluctuation of the driving force (loss) due to the fluctuation of the friction between the torsion spring and the sleeve portion and the fluctuation of the driving force due to the fluctuation of the friction between the torsion spring and the rotating shaft. The total is kept to a minimum to ensure stable rotation motion.

In the second aspect of the invention, the outer diameter of the sleeve portion and the outer diameter of a portion of the rotating shaft axially adjacent to the sleeve portion are made substantially equal to each other so that the sleeve portion and the rotating shaft are adjacent to each other. It is desirable to eliminate a step from the portion so that the torsion spring can be smoothly deformed in the axial direction due to the rotation of the rotating shaft.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a drive unit according to a first embodiment of the present invention. This drive device is used for a part of a shutter mechanism of a camera (not shown). In this figure, 11 is a base plate, and the base plate 11 has fitting holes 11a and 11b formed concentrically. In addition, in the vicinity of the fitting hole 11a in the upper portion of the main plate 11,
A locking rib 11c is formed. Further, a cylindrical sleeve portion 11d is formed around the fitting hole 11a in the upper portion of the main plate 11. Here, the outer diameter of the sleeve portion 11d is D1, and the axial length is L / 2.
It is.

Reference numeral 12 denotes a rotating shaft, which is rotated on the main plate 11 by fitting the fitting shaft portions 12a and 12b formed at both ends (upper and lower ends) in the axial direction into the fitting holes 11a and 11b of the main plate 11, respectively. It is held freely. This rotating shaft 12
The upper side (hereinafter, referred to as the first cylindrical portion) of the axially intermediate portion has an outer diameter that can be rotatably inserted into the sleeve portion 11d, and the lower side (hereinafter, referred to as the second cylindrical portion) is of the sleeve portion 11d. It has an outer diameter D2 which is approximately equal to the outer diameter D1.

A gear portion 12c having an outer diameter larger than the outer diameter (D2) of the second cylindrical portion is formed below the second cylindrical portion of the rotary shaft 12. Further, a ring-shaped projection is formed at a radial intermediate position on the upper surface of the gear portion 12c, and a groove 12d is formed between the projection and the outer peripheral surface of the second cylindrical portion. Further, a part of the protrusion is cut out to form a spring locking portion 12e.

Reference numeral 13 is a torsion spring, which has a coil-shaped portion 13c having a length L in the axial direction. The upper half of the coil-shaped portion 13c is arranged on the outer circumference of the sleeve portion 11d, and the lower half is arranged on the outer circumference of the second cylindrical portion of the rotary shaft 2. The upper and lower ends of the coil-shaped portion 13c have hook portions 13a and 13b extending outward in the radial direction, respectively.
The upper hook portion 13a is locked to the locking rib 11c, and the lower hook portion 13b is locked to the spring locking portion 2e.

For this reason, when the torsion springs 3 attached to the outer periphery of the rotary shaft 12 are assembled into the main plate 11 while being twisted and deformed, the torsion springs 3
Rotation torque in the reverse rotation direction is generated on the rotating shaft 12 by the elastic force generated in the. This rotation torque is
It is transmitted to a coupling gear (not shown) that meshes with c.

When the torsion spring 3 is twisted and deformed, the inner circumference of the upper half of the coil-shaped portion 13c contacts the outer circumference of the sleeve portion 11d, and friction is generated between them. The frictional force increases the loss of the driving force for the connecting gear to which the driving force should be transmitted, as the relative speed between the two increases. Therefore, the lower the relative velocity V1 is, the lower the sleeve portion 11d is, and the larger the loss of the driving force is.

Similarly, the inner periphery of the lower half of the coil-shaped portion 13c contacts the outer periphery of the second cylindrical portion of the rotary shaft 12, and friction is also generated between them. The frictional force also increases the loss of the driving force as the relative speed between the two increases. Therefore, the loss of the driving force becomes larger toward the upper part of the second cylindrical portion where the relative speed V2 is large.

By the way, the loss of the driving force fluctuates due to the change of the friction coefficient, but in order to minimize this fluctuation, it is necessary to suppress the maximum value of the relative speed. In other words, it is necessary that the relative velocities V1 and V2 be substantially equal.

Therefore, in this embodiment, the axial length L of the sleeve portion 11d is different from the axial length L of the coil-shaped portion 13c when the torsion spring 13 is torsionally deformed and a predetermined rotational torque is generated on the rotating shaft 12. The length in the direction and the length in the axial direction of the second cylindrical portion of the rotary shaft 12 are set to L / 2 so that the relative velocities V1 and V2 are substantially equal. As a result, the torsion spring 13 and the sleeve portion 11d
The sum of the fluctuation of the driving force (the loss of the driving force) caused by the fluctuation of the friction between and the fluctuation of the driving force loss caused by the fluctuation of the friction between the torsion spring 13 and the rotating shaft (second cylindrical portion) 12. Is minimized, and the operation of the rotary shaft 12 can be stabilized.

The axial length of the coil-shaped portion 13c changes in accordance with the change in the amount of torsional deformation (that is, the change in the amount of rotation of the rotating shaft 12). If a step is formed between the cylindrical portion, that is, the portion that is adjacent to the sleeve portion 11d in the axial direction, the coil-shaped portion 13c may be caught here, or the coil-shaped portion 13c may bite into the gap between the two. 13c
There is a possibility that the change in the axial length of the rotary shaft 12 may be hindered and the operation of the rotary shaft 12 may become unstable.

Therefore, in the present embodiment, the sleeve portion 11
The outer diameter D1 of d and the outer diameter D2 of the second cylindrical portion are made substantially equal to each other so that there is no step between them.

Although the sleeve portion is formed in a cylindrical shape in the above embodiment, the present invention is not limited to such a shape, and a plurality of sleeve pieces having an arcuate outer peripheral surface may be used.

Further, the present invention may be used by combining the above-described embodiments and modified examples, or the technical elements thereof as needed.

(Relationship Between Embodiments and Claims) In the above-described embodiments, the base plate 11 serves as a base member as claimed, the rotary shaft 12 as a rotary shaft as claimed, and the sleeve portion 11d. The torsion spring 13 corresponds to the sleeve portion in the claims, and corresponds to the torsion spring in the claims.

The above is the correspondence relationship between each configuration of the present invention and each configuration of the embodiment, but the present invention is not limited to the configuration of these embodiments, and the mechanism or the embodiment shown in the claims is not limited. Any structure may be used as long as the function of the structure can be achieved.

[0028]

As described above, in the first invention of the present application, the sleeve portion formed in the ground member is inserted between the rotary shaft and the torsion spring. Therefore, according to the present invention, the gap formed between the base member and the end of the rotary shaft can be covered with the sleeve, and the end of the torsion spring can be prevented from cutting into the gap.

Further, in the second aspect of the present invention, the axial length of the sleeve portion is approximately ½ of the axial length of the torsion spring. Therefore, according to the present invention, the total of the fluctuation of the driving force due to the fluctuation of the friction between the torsion spring and the sleeve and the fluctuation of the driving force due to the fluctuation of the friction between the torsion spring and the rotating shaft is minimized. Therefore, stable rotation operation can be obtained.

If the outer diameter of the sleeve portion and the outer diameter of the portion of the rotating shaft axially adjacent to the sleeve portion are made substantially equal, there is no step between the sleeve portion and the adjacent portion of the rotating shaft, and rotation The axial deformation of the torsion spring due to the rotation of the shaft can be smoothly performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a drive device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional drive device.

[Explanation of symbols]

 1,11 Ground plate 1d, 11d Sleeve part 2,12 Rotating shaft 3,13 Torsion spring 3a, 3b, 13a, 13b Hook part

Claims (3)

[Claims] 1. A rotary shaft having at least one axial end rotatably held by a ground member, and a rotary shaft attached to the outer periphery of the rotary shaft, one end of which is locked to the ground member and the other end of which is attached to the rotary shaft. In a drive device having a torsion spring that is locked and biases the rotation shaft in the rotation direction, the base member is provided with a sleeve portion that is inserted between the rotation shaft and the torsion spring. A drive device characterized by the above. 2. The drive device according to claim 1, wherein an axial length of the sleeve portion is approximately ½ of an axial length of the torsion spring. 3. The drive device according to claim 1, wherein an outer diameter of the sleeve portion and an outer diameter of a portion of the rotating shaft that is adjacent to the sleeve portion in the axial direction are substantially equal to each other. .