JP3169557B2 - Spring clutch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a spring in which a common spring is wound around the outer peripheral surfaces of a first member and a second member so that both members can rotate relatively in one direction but cannot rotate in the opposite direction. A part of the spring bites into the gap between the mutually opposing surfaces of the first member and the second member due to the diameter reduction of the spring when a strong rotational force is applied to one of the members in the non-rotatable direction, particularly regarding the clutch. The present invention relates to a spring clutch that has prevented the above.

[0002]

2. Description of the Related Art A spring clutch of this type is generally constructed as shown in FIG. In the figure, 2 is a shaft, 4 is a first member fixedly fitted to the outer periphery of the shaft 2, 6 is a second member with a gear rotatably inserted into the shaft portion 4b of the first member, 8 is Boss portions 4 of first and second members 4 and 6
The springs 10 wound so as to be in sliding contact with the outer peripheral surfaces of the a and 6a are covers 10 and 12 loosely fitted so as to cover the outer periphery of the spring 8, and the shafts of the first member for preventing the second member from being pulled out. It is a claw formed at the tip of the portion 4b.

[0003] One end of the spring 8 is fixed to the first member 4 and the second member 6 is allowed to rotate relative to the first member 4 in a direction opposite to the direction in which the spring 8 is wound. When a rotational force acts in the opposite direction, that is, in the winding direction of the spring 8, the spring 8 is twisted in the diameter-reducing direction by friction with the boss portion 6 a of the second member 6, and the boss portion 6 a of the second member 6 and the inside of the spring 8 are rotated. A strong frictional force acts on the peripheral surface to restrict the rotation of the second member 6.

[0004]

In the conventional spring clutch, when a strong force is applied to the second member 6 in a non-rotatable direction, the diameter of the spring 8 is reduced and a part of the spring 8 becomes the first member.
The member 4 and the second member 6 may bite into the gap C between the opposing surfaces of the boss portions 4a and 6a, and the members 4 and 6 may fall into a so-called locked state in which the members 4 and 6 cannot rotate in any direction. . This is because the wire diameter of the spring 8 is, for example, 0.5 m.
In the case of m, the gap C between the opposing surfaces of the boss portions 4a and 6a is set to a narrower value, usually 0.1 to 0.3 mm, to prevent the spring from biting.
However, if the angle C is slightly inclined with respect to the first member 4, the gap C may expand and exceed the wire diameter of the spring 8.

The reason why the second member 6 tilts is that there is a slight gap between the second member 6 and the shaft portion 4b of the first member 4 for smooth rotation. The gap C is formed around the retaining claw 12 at the tip of
Is relatively large, close to the wire diameter of the spring 8.

An object of the present invention is to provide a first member 4 and a second member 6
By suppressing as much as possible the gap C between the opposing surfaces of the boss portions 4a and 6a, the first member 4
Another object of the present invention is to provide a spring clutch in which the spring 8 does not bite into the gap C between the first member 4 and the second member 6 even when a strong rotational force is applied to the second member 6 in a non-rotatable direction.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a first member having a shaft portion at one end and a first boss portion having a larger diameter than the shaft portion; A second member rotatably fitted to the outer periphery of a shaft portion of the member and having a second boss portion having the same diameter as the first boss portion and adjacent to the first boss portion; A spring disposed over the outer peripheral surface of the two bosses, having a spring in sliding contact with the outer peripheral surfaces of the first boss and the second boss, and having one end fixed to the first or second member; In the clutch, an annular first engagement step is formed on the inner peripheral surface of the base of the boss of the second member, and the second engagement step is engaged on the outer peripheral surface of the shaft with the engagement step. The first member and the second member are relatively inclined about the first and second engagement steps, and The maximum gap generated between the first boss mutual facing surface of the second boss portion was set to smaller than the wire diameter of the spring.

Accordingly, even if the gap between the opposing surfaces of the first boss portion and the second boss portion is maximized, the spring does not bite into this gap, thereby preventing the spring clutch from falling into a so-called locked state. be able to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the spring clutch of the present invention has an annular first engagement step 14 formed on the inner peripheral surface of the base of the boss 6 a of the second member 6 and a shaft 4 b of the first member 4. A second engagement with the first engagement step 14 on the outer peripheral surface
It is characterized in that an engaging step 16 is formed and the second member 6 is prevented from being pulled out by mutual engagement of the engaging steps 14, 16, and the other parts have the same configuration as the conventional one. .

Specifically, as shown in FIGS. 1A and 1B,
A first member 4 made of resin is fitted to the metallic shaft 2, and the shaft 2 and the first member 4 are fixed to each other by a pin 3 penetrating in a diameter direction. At one end of the first member 4,
A hollow shaft portion 4b and a first boss portion 4a having a larger diameter than the shaft portion 4b are formed adjacently and concentrically. A second member 6 made of resin is rotatably fitted to the outer periphery of the shaft portion 4b of the first member 4. The second member 6 is adjacent to the gear portion 6b and the first boss portion 4a of the first member 4, and
It has a second boss 6a having the same diameter as the first boss 4a.

The first boss portion 4a and the second boss portion 6a are formed of a metallic ring in consideration of wear resistance, and are integrally fitted to the first member 4 and the second member 6, respectively. And
The spring 8 extends over the outer peripheral surfaces of the bosses 4a and 6a.
Is wound. The spring 8 is formed by winding a rectangular wire having a rectangular cross section in a coil shape, and the inner peripheral surface thereof is in sliding contact with the outer peripheral surfaces of the first boss portion 4a and the second boss portion 6a, and one end is as shown in FIG. It is inserted and fixed in a groove 18 formed in the first member 4. A cylindrical cover 10 is disposed outside the spring 8 with a slight gap from the outer peripheral surface of the spring 8. Both ends of the cover 10 are loosely fitted to the outer peripheral surfaces of the first member 4 and the second member 6. ing. A slit groove 20 is formed at one end of the cover 10, and the other end of the spring 8 is fitted into the slit groove 20.

The annular first engaging step 14 is formed on the inner peripheral surface of the base of the boss 6a of the second member 6, as described above. In addition, the first member 4 has a first outer surface on the outer surface of the shaft portion 4b.
A second engagement step portion 16 that engages with the engagement step portion 14 is formed. These engaging step portions 14 and 16 ensure a larger contact area than the conventional claw portion 12 in order to increase the rigidity of the second member 6 in the axial direction. In detail, as shown in FIG. 1A, the second engagement step 16 is formed on the outer surface of a pair of diametrical tongue pieces 24 formed by cutting a slit 22 from the tip of the shaft 4b. It is formed integrally. Tongue piece 2
Numeral 4 has a moderate elasticity in the radial direction, and is slightly displaced inward in the radial direction when the second member 6 is fitted to the shaft portion 4b so as to allow the insertion of the second member 6 into the shaft portion 4b. It has become.

The spring clutch of the present invention is constructed as described above. When the first member 4 is used as the fixed side and the second member 6 is used as the rotating side, the second member 6 is turned in the opposite direction to the winding direction of the spring 8. When the second member 6 is rotated, the spring 8 expands in diameter due to the friction between the outer peripheral surface of the boss portion 6a of the second member 6 and the inner peripheral surface of the spring 8, so that the rotation of the second member 6 is allowed. When the second member 6 is rotated in the same direction as the winding direction of the spring 8, the spring 8 is reduced in diameter by friction between the boss portion 6a of the second member 6 and the inner peripheral surface of the spring 8, so that the rotation of the second member 6a Is restrained.

Here, when the second member 6a is strongly rotated in the rotation restricting direction, the diameter of the spring 8 is reduced, and a part of the spring 8 is inserted into the gap C between the first boss portion 4a and the second boss portion 6a. Try to dig into it. In the conventional spring clutch, since the gap C is relatively easily opened, there is a problem that the rotation of the second member 6 is locked in any direction due to the bite of the spring 8 into the gap C. However, in the present invention, the inclination of the second member 6 with respect to the shaft portion 4b is determined by the engagement of the second member 6 with respect to the shaft portion 4b because the second member 6 is stopped and locked by the engagement of the first and second engagement step portions 14, 16. 1
4, 16 and the bosses 4a, 6a
The gap C between each other becomes zero on one side and becomes maximum on the other side. However, since the maximum gap C is set smaller than the wire diameter of the spring 8, the spring 8 does not bite into the gap C. For example, the wire diameter (axial direction width) of the spring 8 is 0.5 mm, and the size of the gap C in a normal state is 0.3 mm.
In the conventional spring clutch, the gap C may easily expand to almost the same as the wire diameter of the spring 8, but in the spring clutch of the present invention, the gap C
0.4m is much narrower than the diameter of the spring 8
It was found that it can be suppressed to m or less. Therefore, even if a strong rotational force is applied to the second member 6 in the rotation restricting direction, there is no risk of the spring 8 biting into the gap C. If the wire diameter of the spring 8 is set slightly larger, for example, about 0.8 mm, it is possible to more reliably prevent the spring 8 from biting into the gap C.

[0015]

As described above, according to the present invention, the step formed on the inner peripheral surface of the base of the boss of the second member is engaged with the step formed on the outer periphery of the shaft of the first member. Since the two members are prevented from coming off, the inclination angle of the second member is smaller than that of the conventional configuration in which the second member is locked by the claw at the tip of the shaft of the first member. In addition, it is possible to suppress the expansion of the gap generated between the second member and the second member, and it is possible to prevent a situation where a part of the spring bites into the gap.

[Brief description of the drawings]

FIG. 1A is an end view of a spring clutch of the present invention, and FIG. 1B is a sectional view of the spring clutch.

FIG. 2 is an enlarged sectional view of a spring clutch of the present invention.

FIG. 3A is an end view of a conventional spring clutch,
(B) is a sectional view of the spring clutch.

[Explanation of symbols]

 2 Shaft 4 First member 4a First boss 4b Shaft 6 Second member 6a Second boss 6b Gear 8 Spring 10 Cover 14 First engaging step 16 Second engaging step 18 Groove 20 Slit groove 22 Slit 24 Tongue piece

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16D 41/00-47/06 F16D 7/02

Claims (1)

(57) [Claims] A first member having a shaft portion and a first boss portion having a diameter larger than that of the shaft portion at one end thereof concentrically; a first member rotatably fitted to an outer periphery of the shaft portion; ,
A second member having the same diameter as the first boss portion and having a second boss portion adjacent to the first boss portion; and a second member disposed over an outer peripheral surface of the first boss portion and the second boss portion; Sliding contact with the outer peripheral surface of the first boss portion and the second boss portion,
And a spring having one end fixed to the first or second member, wherein an annular first engagement step is formed on an inner peripheral surface of a base of a boss of the second member, and A second engaging step that engages with the engaging step is formed on an outer peripheral surface of a shaft, and the first member and the second member are relatively positioned around the first and second engaging steps. A spring clutch, wherein a maximum gap generated between mutually opposing surfaces of the first boss portion and the second boss portion in an inclined state is set to be equal to or less than a wire diameter of the spring.