JP2023073604A - torque limiter - Google Patents

Abstract

To provide a torque limiter equipped with an inner ring member of low costs, capable of improving durability (wear resistance) and sliding characteristics.SOLUTION: A torque limiter 1 is equipped with an inner ring member 10 around which a coil spring is wound on an outer peripheral surface, and an outer ring member 30 which is arranged so as to cover the inner ring member 10 and to which an end portion of the coil spring is fixed. The inner ring member 10 has a peripheral wall 10a around which the coil spring is wound and slid. The peripheral wall 10a includes a first layer 10aa formed by resin, and a second layer 10ab that is located on the first layer 10aa to form a surface of the peripheral wall 10a, and is made by containing a filler in a base material. The second layer 10ab is provided at a part around which the coil spring is wound.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque limiter that limits load torque associated with rotation transmitted in one direction or rotation transmitted in both directions to a predetermined value or less, and more particularly to a torque limiter characterized by an inner ring member.

In general, a torque limiter interrupts transmission of torque when a large torque exceeding a certain value acts on a rotation transmission mechanism. It is installed in the roller portion of the transport mechanism (paper feeding mechanism). Such torque limiters include contact type torque limiters that obtain rotational torque by mechanical friction. and an outer ring member (also called a case member or housing) that fixes one end of the coil spring and covers the inner ring member.

In addition to limiting the load torque accompanying the rotation transmitted in one direction, the torque limiter also limits the load torque accompanying the rotation transmitted bidirectionally, as disclosed in Patent Document 2, for example. Limitations are known.

JP 2014-145380 Patent No. 3315603

In recent years, demands for small size, high torque, high durability, and high quality have been increasing for such torque limiters. Therefore, the material for forming the inner ring member around which the coil spring is wound is important in order to improve the quality.

Therefore, the inner ring member is generally molded from sintered metal or resin such as polyphenylene sulfide (PPS), polyetheretherketone (PEEK), and polyeximethylene resin (POM). It is conceivable that durability (abrasion resistance) and sliding properties are improved by incorporating carbon fiber as a filler into the base material such as resin.

However, composite materials containing fillers in the base material are expensive, and therefore, the material cost is increasing more and more in recent years when the inner ring member is becoming larger in order to cope with high torque. In addition, when the functions of a gear are integrated (when the gear and the inner ring member are integrated), the size of the inner ring member increases, and there is a possibility that the mating gear part will wear out.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a torque limiter having a low-cost inner ring member capable of improving durability (wear resistance) and sliding characteristics. do.

In order to achieve the above object, the present invention provides an inner ring member having a coil spring wound around its outer peripheral surface and an outer ring member arranged to cover the inner ring member and to which the end of the coil spring is fixed. and a torque limiter for generating a predetermined torque between the inner ring member and the outer ring member by the frictional force between the inner ring member and the coil spring while limiting the torque to a predetermined value or less, wherein the inner ring member has a peripheral wall around which the coil spring is wound and which is in sliding contact, the peripheral wall forming a first layer formed of resin, and a surface of the peripheral wall positioned on the first layer, and a second layer comprising a base material containing a filler, wherein the second layer is provided at a portion around which the coil spring is wound.

According to the above configuration, the surface of the peripheral wall of the inner ring member on which the coil spring is wound and is in sliding contact is formed of the second layer containing the filler in the base material. Therefore, the base material and the filler are appropriately selected. This makes it possible to improve the durability (wear resistance) and sliding properties of the inner ring member. In addition, although the second layer of such a composite material, which is made of a base material containing a filler, is generally expensive, in the above configuration, the second layer is formed on the peripheral wall of the inner ring member around which the coil spring is wound and held. Since the first layer, which is the lower layer, is formed of resin only on the surface, it is possible to reduce the cost of the entire inner ring member by using an inexpensive resin as the material for forming the first layer. It becomes possible.

That is, the inner ring member of the torque limiter having the above configuration according to the present invention uses an expensive composite material for improving its durability (abrasion resistance) and sliding characteristics only on the surface layer of the peripheral wall around which the coil spring is wound and held. , The peripheral wall is composed of two separate layers so that the other materials can be formed from inexpensive resin materials, so durability (abrasion resistance) and sliding characteristics are improved, and low cost is achieved at the same time. can. In this case, the thickness of the second layer is preferably thinner than that of the first layer, and may be in the range of 0.4 to 1.0 mm.

Examples of the resin material forming the first layer include resin materials such as POM and PA (nylon). For the second layer, for example, polyether ether ketone or polyphenylene sulfide as a base material to which a filler containing carbon fiber, polytetrafluoroethylene, or graphite is added can be used. According to this, the durability (wear resistance) and sliding characteristics of the inner ring member can be improved, and the wear of the outer ring member in sliding contact with the inner ring member can be suppressed.

Here, among the materials to be added, carbon fiber mainly contributes to improvement in strength and wear resistance (improvement in durability), and can also contribute to improvement in sliding properties. In addition, among the added materials, polytetrafluoroethylene and graphite contribute to the improvement of slidability. It has good heat resistance, load resistance, and wear resistance against the increase in pressure of the coil spring, and these complement the functions and stabilize the performance. As the base material, other materials such as polyimide can be used, but polyetheretherketone can exhibit the most excellent properties as the base material. For this reason, if the inner ring member is formed of a composite material having such a base material and the above-described filler, the torque limiter can be made smaller, and even if it is constructed as a high-torque type, the torque is excellent in durability and sliding characteristics. It is possible to configure a limiter.

Moreover, in the above configuration, the first layer and the second layer may be integrally formed. Such integral molding can be realized, for example, by a two-color molding technique. Moreover, in the above configuration, the first layer and the second layer may be separate bodies. In that case, for example, the second layer is formed in the shape of a thin sleeve, the first layer is integrally formed with other parts of the inner ring member, and the sleeve is the inner ring member (the first layer integrated with the inner ring member). layer) so as to be non-rotatable (for example, detachable).

According to the torque limiter of the present invention, it is possible to provide a torque limiter including a low-cost inner ring member capable of improving durability (wear resistance) and sliding characteristics.

1 is a sectional view showing one configuration example of a torque limiter according to the present invention; FIG. FIG. 2 shows a configuration of the torque limiter in FIG. 1 with the coil spring removed, and schematically shows the structure of the peripheral wall of the inner ring member.

A torque limiter according to an embodiment of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 shows one configuration example of a torque limiter according to the present invention. As shown in the figure, this torque limiter 1 includes a cylindrical inner ring member (also called a bobbin) 10 and a cap-shaped outer ring member (case) mounted to cover the inner ring member 10 . (also referred to as a member or housing) 30 and a coil spring 40 mounted on the outer peripheral surface of the inner ring member 10 .

The illustrated coil spring 40 is a one-way coil spring (for example, left-handed), and one end 40 a is fixed to the outer ring member 30 . Therefore, when a predetermined rotational torque is generated from the outer ring member 30 in one direction, the inner ring member 10 and the outer ring member 30 perform a function of causing them to slide (turning off power transmission between the inner ring member 10 and the outer ring member 30). Specifically, when the outer ring member 30 rotates in the direction of arrow D1 in FIG. When the one-way coil spring 40 rotates in the direction of the arrow D2, the one-way coil spring 40 expands (relaxes) in the radial direction. A slip occurs between 10a and the inner surface of the one-way coil spring 40 mounted thereon, and power transmission is turned off. That is, such a torque limiter 1 is always in a state of power transmission for rotation in one direction, and for rotation in the opposite direction, slippage between the inner ring portion 10 material and the outer ring member 30 does not occur when a predetermined torque acts. and the power transmission is turned off.

Note that the torque for turning off the power transmission can be adjusted by the tightening force of the one-way coil spring 40 . Further, it is possible to wind a clockwise unidirectional coil spring having a similar structure around the inner ring member 10, and in this case, the effect opposite to that described above can be obtained. Furthermore, it is possible to wind a bidirectional coil spring around the inner ring member 10. In this case, when a predetermined torque is applied to rotation in both directions, slip occurs and power transmission is turned off. becomes. That is, when the load torque in any rotational direction is equal to or less than the torque limit value, the torque is transmitted (ON state), and when the load torque exceeding the torque limit value is applied, the torque transmission is blocked (OFF state). situation).

The inner ring member 10 is formed in a hollow and substantially cylindrical shape, and a shaft (not shown) is inserted through an internal passage 10A. A locking pin (not shown) is provided on the shaft in a direction orthogonal to the axial direction, and a cutout recess 11 that engages with the locking pin is formed radially on one end side of the inner ring member 10 . there is Thereby, the shaft and the inner ring member 10 are rotationally fixed.

The inner ring member 10 has the aforementioned circumferential wall (surrounding wall) 10a, and the one-way coil spring 40 or the two-way coil spring is wound and held on the surface (outer peripheral surface) thereof. A peripheral wall 10b having a diameter smaller than that of the peripheral wall 10a is formed on the other end side of the inner ring member 10, and this portion is fitted into a circular opening 31 formed in the top plate wall 30a of the outer ring member 30, thereby forming an outer ring member. The top plate wall 30a side of 30 is positioned. A flange 12 is integrally formed on the circumferential wall 10a via a plurality of base portions protruding radially at predetermined intervals along the circumferential direction. A coil spring is wound and held on the surface of the circumferential wall 10a. 40 movements are restricted. At the outer peripheral end of the flange 12, a pair of projections 30c are formed at two locations (two locations at 180° intervals) on the inner peripheral surface of the circular opening 30A of the outer ring member 30 when the outer ring member 30 is attached. The inner ring member 10 is prevented from coming off from the outer ring member 30 . The number of projections to be formed is not limited, and for example, three projections may be formed at intervals of 120°.

As described above, the outer ring member 30 is formed like a cap, and includes a top plate wall 30 a and a circumferential wall 30 b that covers the circumferential wall 10 a of the inner ring member 10 . A circular opening 31 into which the circumferential wall 10b of the inner ring member 10 is fitted is formed in the center region of the top plate wall 30a. As described above, the inner peripheral surface of the end portion of the peripheral wall 30b located on the circular opening 31 side is engaged with the flange 12 of the inner ring member 10 to prevent the inner ring member 10 from coming off the outer ring member 30. A plurality of preventing projections 30c are provided.

FIG. 2 shows a configuration from which the coil spring 40 is removed, and is a diagram schematically showing the inner ring member.
Circumferential wall 10a of inner ring member 10, on which coil spring 40 is wound and slidably contacted, is formed of first layer 10aa made of resin, and is positioned on first layer 10aa to form the surface of circumferential wall 10a. , and a second layer 10ab comprising a base material containing a filler. In this embodiment, the circumferential wall 10a consists of only two layers 10aa and 10ab, but may include other layers.

In this case, the thickness of the second layer 10ab is preferably thinner than that of the first layer 10aa so as to reduce the weight and cost of the entire device. For example, the thickness of the second layer 10ab is preferably 0.4-1.0 mm. As the resin forming the first layer 10aa, resin materials such as POM and PA (nylon) can be used. The second layer 10ab, which is in contact with the coil spring, is made of polyetheretherketone or polyphenylene sulfide as a base material to which a filler including carbon fiber, polytetrafluoroethylene, and graphite is added. As a result, the durability (wear resistance) and sliding characteristics of the inner ring member 10 can be improved.

Here, among the materials added to the second layer 10ab, carbon fiber mainly contributes to improvement in strength and wear resistance (improvement in durability), and also contributes to improvement in sliding characteristics. obtain. In addition, among the added materials, polytetrafluoroethylene and graphite contribute to the improvement of slidability. It has good heat resistance, load resistance, and wear resistance against the increase in pressure of the coil spring, and these complement the functions and stabilize the performance. As the base material, other materials such as polyimide can be used, but polyetheretherketone can exhibit the most excellent properties as the base material. For this reason, when the inner ring member 10 is formed of a composite material including such a base material and the above-mentioned filler, the torque limiter can be made smaller, and even if it is constructed as a high-torque type, it has excellent durability and sliding characteristics. It is possible to configure a torque limiter.

Also, the second layer 10ab may be made of other composite materials capable of improving the durability (wear resistance) and sliding properties of the inner ring member 10, such as POM and PA.

The two-layer structure as described above can be formed by integrally molding the first layer 10aa and the second layer 10ab using, for example, a two-color molding technique. The layer 10ab may be configured as a separate body. In that case, for example, the second layer 10ab is formed in a thin sleeve shape, the first layer 10aa is integrally formed with other parts of the inner ring member 10, and the sleeve-shaped second layer 10ab is formed in the inner ring member 10 (inner ring member 10). It may be non-rotatably (for example, detachably) locked to the first layer 10aa) integral with the member 10. FIG.

As described above, according to the present embodiment, the surface of the circumferential wall 10a of the inner ring member 10, on which the coil spring 40 is wound and slidably contacted, is formed of the second layer 10ab made of the base material containing the filler. Therefore, it is possible to improve the durability (wear resistance) and sliding characteristics of the inner ring member 10 by appropriately selecting the base material and filler. In addition, the second layer 10ab of such a composite material, which is made of a base material containing a filler, is generally expensive. Only the surface of the circumferential wall 10a of the member 10 is limited, and the first layer 10aa, which is the lower layer, is formed of resin. The cost of the entire inner ring member 10 can be suppressed.

That is, the inner ring member 10 of the torque limiter 1 of the present embodiment is made of an expensive composite material that improves its durability (wear resistance) and sliding characteristics only on the surface layer of the circumferential wall 10a around which the coil spring 40 is wound and held. Circumferential wall 10a is composed of two separate layers 10aa and 10ab so that other materials can be formed from inexpensive resin materials, improving durability (abrasion resistance) and sliding characteristics. and low cost can be realized at the same time.

1 torque limiter 10 inner ring member 10a peripheral wall 10aa first layer 10ab second layer 30 outer ring member 40 coil spring

Claims (4)

An inner ring member around which a coil spring is wound and held, and an outer ring member disposed so as to cover the inner ring member and to which an end of the coil spring is fixed, wherein the inner ring member and the coil spring are connected together. A torque limiter that generates a predetermined torque between the inner ring member and the outer ring member by frictional force and limits the torque to a predetermined value or less,
The inner ring member has a peripheral wall around which the coil spring is wound and slidably contacted,
The peripheral wall includes a first layer formed of a resin, and a second layer positioned on the first layer to form the surface of the peripheral wall and having a base material containing a filler. ,
The torque limiter, wherein the second layer is provided at a portion around which the coil spring is wound. 4. The second layer is composed of polyether ether ketone or polyphenylene sulfide as a base material, to which a filler including carbon fiber, polytetrafluoroethylene, and graphite is added. 1. The torque limiter according to 1. 3. The torque limiter according to claim 1, wherein said first layer and said second layer are formed integrally. 3. The torque limiter according to claim 1, wherein said first layer and said second layer are separate bodies.

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