JPH05248448A - Torque limiter - Google Patents

Abstract

PURPOSE:To improve the function of a torque limiter which races a member on the drive side when an overload is exerted on a member on the driven side and to save the number of parts and the number of assembly processes through simplification of structure. CONSTITUTION:A cylindrically protruded sleeve 10 is integrally formed on the under surface of an operation dial 6. A curved surface 10a is formed on the inner surface of the sleeve 10. A cam surface 8a wherein a plurality of cylindrical surfaces are rotationally symmetrically arranged is formed on the outer periphery of a cam 8. Rotation of the operation dial 6 is transmitted to the cam 8 in a state that the curved surface 10a is engaged with the cam surface 8a. When the operation dial 6 is rotated in a state that rotation of the cam 8 is prohibited, the sleeve 10 is resiliently deformed in such away that the curved surface 10a is moved over the cam surface 8a and the operation dial 6 is raced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque limiter in which, when an overload is applied to a driven member, the drive member and the driven member are disengaged from each other so that only the drive member idles.

[0002]

2. Description of the Related Art For example, when a drive gear is rotated by a motor and torque is transmitted to a driven gear meshed with the drive gear, if the motor is continuously driven while the rotation of the driven gear is blocked, The meshing part with the driven gear may be damaged,
Alternatively, a failure such as a burnout of the motor will occur. When such a failure may occur, a friction mechanism is generally provided in the drive transmission path from the motor to the drive gear to prevent an excessive torque from being transmitted to the drive gear. In particular, the drive member and the driven member have a common center of rotation, the rotation of the drive member is transmitted to the driven member as it is in the normal state, and when the driven member is overloaded, the drive member slips with respect to the driven member. A structure that rotates idly is called a torque limiter, and various forms are known.

A torque limiter, which is often used in general consumer equipment, is a torque of a driving member, which is formed by pressing a driving member and a driven member directly or by sandwiching a friction plate between these members by a biasing force of a spring. Is transmitted to the driven member by frictional engagement. When the drive member is rotated while the driven member is overloaded, only the drive member slips and spins idle. According to this structure,
By adjusting the biasing force of the spring to change the pressure-bonding force between the drive member and the driven member, the upper limit value of the torque to be transmitted to the driven member can be set arbitrarily.

[0004]

However, in the case of the conventional torque limiter as described above, in order to secure the frictional engagement between the driving member and the driven member during normal driving, these members are crimped with a predetermined force. A spring is required to make it work. Moreover, in order to keep the upper limit value of the torque transmitted to the driven member substantially constant, it is necessary to use a spring mounting structure that does not change the crimping force, and the number of parts is reduced. The number is increasing and assembly is troublesome. Furthermore, when only the drive member idles due to the torque limit function, the frictional engagement surfaces of the drive member and the driven member rub against each other while the crimping force of the spring is still applied. Each frictional engagement surface is subject to wear, and the driving member easily slips with respect to the driven member.

The present invention has been made to solve the problems of the prior art, and provides a torque limiter capable of reducing the number of parts and the number of assembling steps and obtaining a reliable torque limit function. The purpose is to do.

[0006]

In order to achieve the above object, the present invention comprises a drive member and a driven member which are integrally molded, and one of which is provided with a plurality of convex parts so as to be rotationally symmetrical with respect to the center of rotation. A cam having the parts arranged on the peripheral surface is integrally formed, and on the other side, a plurality of concave portions into which the convex portions are inserted are formed integrally with a cylindrical protruding portion provided on a surface facing the peripheral surface of the cam. This cylindrical protrusion is flexible in the direction away from the peripheral surface of the cam, and when the drive member is rotated while the driven member is overloaded, it receives a pressing force from the convex portion. Elastically deforms to allow the convex portion of the cam peripheral surface to escape from the concave portion of the cylindrical protruding portion. Therefore,
In this case, only the drive member runs idle. Further, when the load on the driven member is small, the engagement between the convex portion of the cam and the concave portion of the cylindrical protruding portion is maintained, and the rotation of the driving member can be transmitted to the driven member. Further, in the state where the cam and the cylindrical protruding portion are engaged with each other for transmitting the driving force, a contact portion and a non-contact portion are provided between them and the shape of the contact portion is made non-linear. Therefore, a smooth torque limit function can be obtained.

[0007]

FIG. 2 shows the outer appearance of a waterproof case for a film unit with a lens in which the torque limiter of the present invention is applied to a winding operation section. As shown in FIG. 3, the lens-fitted film unit 3 is housed inside the waterproof case 2 made of transparent resin, and the bottom cover 4 is fitted on the bottom surface to keep the inside of the waterproof case 2 watertight. To be done. The waterproof case 2 is provided with a release operation lever 5 and an operation dial 6 for winding a film, which allows the lens-fitted film unit 3 to be operated from outside the waterproof case 2.

The operation dial 6 is rotatably attached to the upper surface of the waterproof case 2 together with the cam 8 by a split pin 7 serving as a rotary shaft. Operation dial 6 which is a member on the drive side
Is an integrally molded product of resin.
As shown in (A), a flexible sleeve 10 is integrally formed in the recess 6a while being hollowed out. As shown in FIG. 2B, the petal-shaped cam surface 8 of the cam 8 is formed on the inner wall of the sleeve 10.
When a curved surface 10a is formed following the shape of a and the operation dial 6 and the cam 8 are fixed to the upper surface of the waterproof case 10 with the split pin 7, the cam surface 8a fits into the curved surface 10a. Cam surface 8
The a and the curved surface 10a are configured by arranging eight cylindrical surfaces having substantially the same curvature so as to be rotationally symmetrical about the split pin 7. Then, the cam 8 serves as a driven member driven by the operation dial 6.

A gear 12 is integrally formed on the lower surface of the cam 8 and meshes with an interlocking gear 13 pivotally mounted on the waterproof case 2. As shown in FIG. 3, the interlocking gear 13 further includes a shaft 15
A winding gear 14 is also provided integrally therewith and meshes with a winding dial 16 of the lens-fitted film unit 3. The winding dial 16 operates a film winding mechanism and a shutter setting mechanism built in the lens-fitted film unit 3. Like the general camera, the lens-fitted film unit 3 also has a built-in winding stop mechanism. When the film is fed by one frame by rotating the winding dial 16, the winding stop is applied to rotate the winding dial 16. To lock.

When a photograph is taken by operating the release operation lever 5, the winding dial 16 is unlocked and the film can be wound. To wind the film from the outside of the waterproof case 2, the operation dial 6 may be rotated in the film winding direction indicated by the arrow in FIG. When the operation dial 6 rotates in the film winding direction and the sleeve 10 rotates together with it, the curved surface 10a and the cam surface 8 are rotated.
The cam 8 also rotates in the same direction by the engagement with a. Cam 8
Is transmitted to the interlocking gear 13 via the integrated gear 12 to rotate the winding gear 14. During the film winding period, a large load is not applied to the winding dial 16 of the lens-fitted film unit 3, so that the winding gear 1
The winding dial 16 is rotated by the rotation of 4, so that the film is wound as the operation dial 6 is rotated. When the film has been wound up for just one frame, the winding stop mechanism of the lens-fitted film unit 3 is activated to lock the winding dial 16.

When the winding dial 16 is locked, the rotation of the cam 8 is also prohibited. When the operation dial 6 is further rotated in this state, the sleeve 10 formed on the lower surface of the operation dial 6 is pressed from the inner surface side by the cam surface 8a and is curved outward as shown by the broken line in FIG. 1 (A). As a result, as shown in FIG. 4, the curved surface 10a of the sleeve 10 slides on the cam surface 8a, and only the operation dial 6 idles by this sliding. Therefore, the driving force applied to the operation dial 6 is not transmitted to the winding dial 16 of the lens-fitted film unit 3 and an extra load is not applied to the winding mechanism of the lens-fitted film unit. Further, the lens-fitted film unit 3 is provided with a reverse rotation preventing mechanism so as to prevent the winding dial 16 from being reversed inadvertently, but the cam surface 8a and the curved surface 10a have a shape with no difference in the rotational direction. Therefore, when the operation dial 6 is rotated in the reverse direction, the torque limit function works in exactly the same manner.

When the operation dial 6 idles, in the case of the illustrated embodiment, the cam surface 8a and the curved surface 10a return to the original engaged state each time the operation dial 6 is rotated by 45 °, and a click feeling is obtained. The photographer can easily identify that the operation state is different from the normal film winding. Further, the torque required to cause slip between the cam surface 8a and the curved surface 10a is determined by the winding gear 1
4 and the winding dial 16 or the strength of the winding mechanism of the lens-fitted film unit 3, the elastic force of the resin material forming the sleeve 10 and the thickness of the sleeve 10, Cam surface 8a
It can be set appropriately by changing the number of petal-shaped protrusions constituting the. Further, it is also possible to adjust the engagement strength between the cam 8 and the sleeve 10 by adjusting either the outer diameter of the cam 8 or the inner diameter of the sleeve 10 to set the torque. 5 kg
It is suitable as a torque limiter where the torque limit function works in the range of -cm.

In the above embodiment, the cam surface 8a and the curved surface 1
The space 18 is formed at the boundary of each cylindrical surface forming the cam surface 8a in the state of being engaged with the cam surface 8a. The space 18 serves to prevent the operation force when the operation dial 6 is idling from becoming too large. Moreover, since the cam surface 8a and the curved surface 10a are cylindrical surfaces, not only the torque limit function can be obtained by idling the operation dial 6 even with relatively weak torque, but also when the two slide against each other. It is also effective in preventing abrasion. Further, since such a torque limit function can be obtained without pressing the winding dial 6 and the cam 8 from the axial direction, only a simple split pin 7 can be used to axially attach both.

FIG. 5 shows another embodiment of the present invention. In this embodiment, the cam 20 is formed with a linear cam surface 20a,
On the inner surface of the sleeve 22 integrated with the operation dial 21, a linear engagement surface 22a is formed corresponding to the cam surface 20a. Even if the cam surface 20a and the engagement surface 22a are used, the same torque limiting function as in the above-described embodiment can be obtained. In the case of this embodiment, the cam surface 2
One angle α of the polygonal shape forming 0a is preferably 90 ° or more. Further, as shown in FIG. 6, for example, when the cam surface 25a of the cam 25 is hexagonal, the sleeve 2
The inner surface of 6 may be provided with twelve recesses 26a as shown in the drawing, and these may form the engaging surface.

FIG. 7 shows an example in which the torque limit mechanism of the present invention is incorporated after the winding dial of the lens-fitted film unit. In the figure, the winding dial 30 is rotatably incorporated in the main body 31 of the lens-fitted film unit, and is operated by the photographer during film winding. Further, the cam 8 shown in FIG. 1 is integrally provided on the lower surface of the winding dial 30. Winding dial 30
A winding stop plate 32 is rotatably incorporated under the. Teeth are engraved on the outer circumference of the winding stop plate 32, and rotation of the clockwise direction is prohibited by engagement of a check claw (not shown). A winding stop claw (not shown) is further engaged with and disengaged from the tooth cut on the outer circumference of the winding stop plate 32.
The winding stop claw engages with the winding stop plate 32 to prevent its rotation when the film is wound up one frame, and is disengaged at the time of shutter release to enable the winding operation. The sleeve 10 shown in FIG. 1 is integrally provided on the upper surface of the winding stop plate 32, and is engaged with the cam surface 8a. Further, the winding stop plate 32
A fork 33 is integrally provided on the lower surface of the cartridge, and is engaged with a cartridge shaft 35 of a cartridge 34 previously built in the main body 31 of the lens-fitted film unit.

According to the above construction, when the winding dial 30 is rotated counterclockwise after photographing, the cam 8 and the sleeve 10 are engaged with each other, the winding stop plate 32 is rotated in the same direction, and the fork 33 is moved. Since the Patrone shaft 35 rotates through the film, film winding can be performed. When the film is wound up by just one frame, the winding stop claw engages with the winding stop plate 32 to prevent its rotation. Therefore, when the winding dial 30 is rotated thereafter, the sleeve 10 is rotated.
Is deformed by the pressing force from the cam surface 8a, the rotation of the cam 8 is not transmitted to the winding stop plate 32, and the winding dial 30 idles to obtain the same function as that of the embodiment described above.

The above description has been made according to the illustrated embodiment. For example, in FIG.
May be integrally formed, and the sleeve 10 may be integrated on the gear 12 side. Further, instead of forming the cam surface 8a on the outer periphery of the cam 8 and engaging the sleeve 10 on the outer side thereof, for example, an inner peripheral cam having a cam surface on the inner side is integrated with the lower surface of the operation dial 6, and the upper surface of the gear 14 is integrated. In addition, a sleeve that bends inward by pressing the inner peripheral cam may be integrated. Also,
The present invention can be applied not only to the waterproof case and the lens-fitted film unit described above, but also to a general driving force transmission mechanism.

[0018]

As described above, according to the present invention, the driving member and the driven member, which are integrally molded, are integrally molded with the cam or the cylindrical protrusion, respectively. And are engaged with each other from the circumferential direction orthogonal to the center of rotation to transmit the driving force, and when the driven side is overloaded, the driving side rotates to disconnect the engagement between the two. It becomes unnecessary to crimp the member and the driven member from the axial direction, and it is possible to obtain a torque limiter having a simple structure and a small number of parts. Further, since it is only necessary to integrally form the cam and the cylindrical protruding portion on the driving member and the driven member respectively, it is possible to obtain a torque limiting function that is reliable and has excellent durability without cost. Furthermore, a smoother torque limit function can be obtained by providing a contact portion and a non-contact portion between the cam and the cylindrical protruding portion, or by forming the contact portion in a non-linear shape. You can

[Brief description of drawings]

FIG. 1 is a vertical sectional view and a horizontal sectional view of a torque limiter using the present invention.

FIG. 2 is an exploded perspective view of a waterproof case incorporating the torque limiter of FIG.

FIG. 3 is a side view showing a state in which a lens-fitted film unit is housed in the waterproof case of FIG.

FIG. 4 is an operation explanatory view of the torque limiter of FIG. 1.

FIG. 5 is a cross-sectional view showing another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing still another embodiment of the present invention.

FIG. 7 is a schematic view showing an example in which the present invention is applied to a film unit with a lens.

[Explanation of symbols]

 2 Waterproof case 3 Film unit with lens 6 Operation dial 7 Split pin 8 Cam 8a Cam surface 10 Sleeve 10a Curved surface 12 Gear 13 Interlocking gear 14 Winding gear 16,30 Winding dial 32 Winding stop plate

Claims (3)

[Claims] 1. A drive member, which is provided between a drive member and a driven member having a common rotation center, transmits torque of the drive member to the driven member, and the drive member rotates in a state where the driven member is overloaded. In a torque limiter that disengages the drive member and the driven member from each other and idles the drive member, the drive member and the driven member are integrally formed, and one of them is rotationally symmetrical with respect to the rotation center. A cam having a peripheral surface in which a plurality of convex portions are arranged is integrally formed so that the other surface of the member has a plurality of concave portions into which the convex portions are respectively inserted on the surface facing the peripheral surface. A cylindrical protruding portion having flexibility in a direction away from the surface is integrally formed, and the rotation of the driving member is transmitted to the driven member by the engagement of the convex portion and the concave portion, and the driven member is overloaded. Driving member in the state Torque limiter for causing idling the driving member by escape the protrusion from the recess by the elastic deformation of the tubular projection when rotated. 2. The torque limiter according to claim 1, wherein a contact portion and a non-contact portion are formed between the cam and the cylindrical protruding portion in a state of being engaged with each other. 3. The torque limiter according to claim 2, wherein the contact portion has a non-linear shape.