JP2021095977A - Torque limiter - Google Patents

Abstract

To provide a new torque limiter in which a flange portion formed on an outer peripheral surface of an inner ring can sufficiently easily overcome an engaging portion formed on an inner peripheral surface of an outer ring, when inserting the inner ring in the inside of the outer ring.SOLUTION: An outer ring 8 is provided with an opening portion 38 corresponding to an engaging portion 34 and penetrating in a diametrical direction. On the inner side of the opening portion 38, a projecting piece 40 is arranged, which projects out in an axial direction from an inner peripheral edge of the outer ring 8 regulating the opening portion 38. The engaging portion 34 is provided on the projecting piece 40.SELECTED DRAWING: Figure 2

Description

The present invention relates to a torque limiter using a coil spring.

The following Patent Document 1 includes an inner ring, a coil spring mounted in contact with the outer peripheral surface of the inner ring, and a tubular outer ring into which the inner ring mounted with the coil spring is inserted. The outer ring has a common central axis, the inner ring is provided with an annular flange extending radially outward, and the outer ring is provided with a plurality of engaging portions extending radially inward. When the inner ring to which the coil spring is mounted is inserted inside the outer ring, the flange portion gets over the engaging portion and engages with the engaging portion in the axial direction, and the coil spring is attached to the outer ring. When a rotational torque around the central axis that irrevocably engages with the inner ring and relatively rotates the inner ring and the outer ring is applied, when the rotational torque is larger than a predetermined value, the coil spring and the coil spring A torque limiter is disclosed in which the outer ring and the inner ring rotate relative to each other by overcoming the frictional force between the inner ring.

Japanese Patent No. 46668706

However, in the torque limiter disclosed in Patent Document 1, when the inner ring is inserted inside the outer ring and the two are combined, a relatively large force is required for the flange portion to get over the engaging portion. , The assembleability was not good enough. Further, when a large force is applied when the flange portion gets over the engaging portion, one or both of the flange portion and the engaging portion is damaged, and the inner ring and the outer ring cannot be engaged in the axial direction. There is also a risk of becoming.

The present invention has been made in view of the above facts, and the main technical problem thereof is that when the inner ring is inserted into the inner ring, the flange portion formed on the outer peripheral surface of the inner ring is sufficiently easily formed on the inner circumference of the outer ring. It is to provide a new and improved torque limiter that can overcome the engagement portion formed on the surface.

As a result of diligent studies, the present inventor has provided an opening in the outer ring that penetrates in the radial direction corresponding to the engaging portion, and the inside of the opening projects axially from the inner peripheral edge of the outer ring that defines the opening. It has been found that the above-mentioned main technical problem can be solved by disposing the projecting piece to be provided and providing an engaging portion on the projecting piece.

That is, according to the present invention, as a torque limiter capable of solving the main technical problem, an inner ring, a coil spring mounted in contact with the outer peripheral surface of the inner ring, and the coil spring mounted. Equipped with a tubular outer ring into which the inner ring is inserted,
The inner ring and the outer ring have a common central axis, the inner ring is provided with an annular flange extending radially outward, and the outer ring is provided with a plurality of engaging portions extending radially inward. Be,
When the inner ring to which the coil spring is mounted is inserted inside the outer ring, the flange portion gets over the engaging portion and engages with the engaging portion in the axial direction, and the coil spring is attached to the outer ring. Engages non-rotatably against
When a rotational torque around the central axis that relatively rotates the inner ring and the outer ring is applied, when the rotational torque is larger than a predetermined value, the frictional force between the coil spring and the inner ring is applied. In a torque limiter in which the outer ring and the inner ring rotate relative to each other
The outer ring is provided with an opening that penetrates in the radial direction corresponding to the engaging portion, and inside the opening, a protruding piece that projects axially from the inner peripheral edge of the outer ring that defines the opening is provided. A torque limiter is provided, wherein the engaging portion is formed on the protruding piece.

Preferably, in the outer ring, a thin wall portion having a reduced radial wall thickness is formed in the circumferential angle region where the opening is formed. It is preferable that one or both of the flange portion and the engaging portion is provided with an overcoming guide means. Preferably, the outer ring is provided with a bearing portion that rotatably supports the axial end portion of the inner ring. It is preferable that a lubricant is sealed inside the outer ring.

In the torque limiter of the present invention, the outer ring is provided with an opening that penetrates in the radial direction corresponding to the engaging portion, and inside the opening, a protrusion that projects axially from the inner peripheral edge of the outer ring that defines the opening. A piece is provided, and the engaging portion is formed on a protruding piece. As a result, the engaging portion can be elastically displaced in the radial direction by bending the protruding piece, so that when the inner ring is inserted into the inner ring, the flange portion formed on the outer peripheral surface of the inner ring is sufficiently easy. It is possible to get over the engaging portion formed on the inner peripheral surface of the outer ring.

The figure which shows the whole structure of the torque limiter configured according to this invention. FIG. 1 is an exploded perspective view of the torque limiter shown in FIG. The figure which shows the inner ring of the torque limiter shown in FIG. 1 by itself. The outer ring of the torque limiter shown in FIG. 1 is shown as a single unit.

Hereinafter, the torque limiter configured according to the present invention will be described in more detail with reference to the accompanying drawings illustrating preferred embodiments of the torque limiter.

Explaining with reference to FIGS. 1 and 2, the torque limiter, which is configured according to the present invention and is indicated by No. 2 as a whole, includes an inner ring 4, a coil spring 6, and an outer ring 8.

Explaining with reference to FIG. 3 together with FIGS. 1 and 2, the inner ring 4 is made of metal and includes a cylindrical inner ring main portion 10. An annular flange portion 12 is provided in the axially intermediate portion of the inner ring main portion 10, and the inner ring main portion 10 has a connection region 14 on one side in the axial direction and the other side in the axial direction with respect to the flange portion 12. It is divided into a mounting area 16. Two notches 18 opened toward the outside in the axial direction are provided at one end in the axial direction of the inner ring 4 (that is, the outer end in the axial direction of the connection region 14) at an angular interval of 180 degrees. The inner ring 4 is connected to an external device on the input side via the notch 18. The flange portion 12 extends radially outward from the outer peripheral surface of the inner ring main portion 10 in a direction perpendicular to the axial direction. A chamfered portion 20 (overcoming guidance means) is provided in the circumferential direction on the outer peripheral edge of the flange portion 12 on the other side surface in the axial direction (that is, the surface opposite to the side on which the notch 18 is formed when viewed in the axial direction). It is continuously formed in.

As shown in FIG. 1, the coil spring 6 is mounted on the outer peripheral surface of the inner ring main portion 10 (more specifically, the mounting region 16 thereof). As understood by referring to FIG. 2 together with FIG. 1, the coil spring 6 is formed by spirally winding a metal wire, and its main portion is circular when viewed in the axial direction. At one end of the coil spring 6 in the axial direction, a hook portion 22 in which the wire rod is bent outward in the radial direction is provided. The inner diameter of the coil spring 6 in the free state is smaller than the outer diameter of the inner ring main portion 10 of the inner ring 4. Therefore, in order to mount the coil spring 6 on the outer peripheral surface of the inner ring 4, first, the hook portion 22 is pressed in the direction in which the coil spring 6 is loosened to expand the diameter of the coil spring 6, and then the diameter of the coil spring 6 is expanded. The inner ring 4 is inserted inside the coil spring 6 to arrange the mounting region 16 inside the coil spring 6, and then the diameter expansion of the coil spring 6 is released. Thus, the coil spring 6 comes into close contact with the outer peripheral surface of the inner ring main portion 10 in the mounting region 16 and is mounted on the inner ring 4.

As shown in FIG. 1, the outer ring 8 is arranged outside the inner ring 4 to which the coil spring 6 is mounted. Explaining with reference to FIG. 4 together with FIGS. 1 and 2, the outer ring 8 is made of synthetic resin and includes a cylindrical outer ring main portion 24. An annular end plate 26 extending inward in the radial direction is formed on the inner peripheral surface of one end of the outer ring main portion 24 in the axial direction. The end plate 26 extends linearly inward in the radial direction from the inner peripheral surface of the outer ring main portion 24, then linearly extends outward in the axial direction, and then straightly extends inward in the radial direction again. An annular bearing portion 28 that rotatably supports the axial end portion of the inner ring 4 is provided inside the end plate 26 in the radial direction. Two connecting pieces 30 straddling the outer ring main portion 24 and the end plate 26 in the axial direction and projecting outward in the axial direction are provided at an angular interval of 180 degrees in the circumferential direction. The outer ring 8 is connected to an external device on the output side via the connection piece 30. The hook portion 22 of the coil spring 6 is inserted into the other end of the outer ring main portion 24 in the axial direction (that is, the end portion on the side opposite to the side on which the end plate 26 is formed when viewed in the axial direction). The hook groove 32 is formed. The hook groove 32 penetrates in the radial direction and extends linearly in the axial direction. The other end of the hook groove 32 in the axial direction is open. At the other end of the outer ring main portion 24 in the axial direction, a plurality of engaging portions (three at equal angular intervals in the circumferential direction in the illustrated embodiment) projecting inward in the radial direction on the inner peripheral surface thereof. 34 is provided. A chamfered portion 36 (overcoming guide means) is continuously formed in the circumferential direction on the axially outer portion of the engaging portion 34.

In the torque limiter of the present invention, the outer ring 8 includes an opening 38 that penetrates in the radial direction corresponding to the engaging portion 34. In the illustrated embodiment, three openings 38 are formed at equal angular intervals in the circumferential direction, and the other end portion of the outer ring main portion 24 in the axial direction (that is, the end plate 26 when viewed in the axial direction) is formed. It is arranged at the end opposite to the formed side). The opening 38 has a rectangular shape in a side view, and the other end in the axial direction is open. Inside the opening 38, a protruding piece 40 that projects axially from the inner peripheral edge of the outer ring 8 that defines the opening 38 is provided. The protruding piece 40 projects linearly from the inner peripheral edge of the outer ring 8 that defines the opening 38 toward the outside in the axial direction (that is, the other side in the axial direction), and the circumferential edges of the protruding piece 40 define the opening 38. It is separated from the inner peripheral edge of the outer ring 8. That is, the protruding piece 40 is a cantilever plate piece having a fixed end on one side in the axial direction and a free end on the other side in the axial direction.
It can be elastically displaced in the radial direction with the fixed end as the base end. In the illustrated embodiment, the other end of the opening 38 in the axial direction was open, but this may be closed. In this case, the protruding piece is closed from the other end in the axial direction to the inside in the axial direction (in this case). That is, it can be made to protrude toward one side in the axial direction). In either case, one of the protruding pieces in the axial direction is a fixed end, while the other in the axial direction is a free end, and both sides in the circumferential direction are separated from the inner peripheral edge of the outer ring that defines the opening. An engaging portion 34 is formed on the inner peripheral surface of the axial tip portion of the protruding piece 40. In the illustrated embodiment, in the outer ring 8, a thin wall portion 42 having a reduced radial wall thickness is formed in the circumferential angle region where the opening 38 is formed. The thin-walled portion 42 is formed by locally increasing the inner diameter of the outer ring main portion 24, and is provided over the entire region between the end plate 26 and the engaging portion 34 when viewed in the axial direction. Therefore, the protruding piece 40 is also made thin.

In order to combine the outer ring 8 and the inner ring 4 to which the coil spring 6 is mounted, the inner ring to which the coil spring 6 is mounted is in a state where the hook portion 22 of the coil spring 6 and the hook groove 32 of the outer ring 8 are aligned. 4 is inserted inside the outer ring 8. The inner ring 4 is made to enter the inside of the outer ring 8 from the side where the mounting area 16 is partitioned. At that time, it is preferable to enclose an appropriate lubricating material such as grease inside the outer ring 8. When the inner ring 4 to which the coil spring 6 is mounted is inserted inside the outer ring 8, the flange portion 12 gets over the engaging portion 34 and engages with the engaging portion 34 in the axial direction, and the coil spring 6 with respect to the outer ring 8. Engage non-rotatably.

In the torque limiter of the present invention, the outer ring 8 is provided with an opening 38 that penetrates in the radial direction corresponding to the engaging portion 34, and the inside of the opening 38 is from the inner peripheral edge of the outer ring 8 that defines the opening 38. A protruding piece 40 projecting in the axial direction is provided, and the engaging portion 34 is formed on the protruding piece 40. As a result, the engaging portion 34 can be elastically displaced in the radial direction by bending the protruding piece 40, so that the engaging portion 34 is formed on the outer peripheral surface of the inner ring 4 when the inner ring 4 is inserted inside the outer ring 8. The flange portion 12 can easily get over the engaging portion 34 formed on the inner peripheral surface of the outer ring 8. In the illustrated embodiment, the flange portion 12 and the engaging portion 34 are provided with the overcoming guide means (chamfered portions 20 and 36), so that the flange portion 12 is more smoothly engaged. You can get over 34. Further, in the illustrated embodiment, the outer ring 8 is further formed with a thin wall portion 42 having a reduced radial wall thickness in the circumferential angle region where the opening 38 is formed. In the circumferential angle region where the engaging portion 34 is formed, the rigidity is reduced, and the flange portion 12 can get over the engaging portion 34 more smoothly.

At the same time as or immediately after the flange portion 12 of the inner ring 4 gets over the engaging portion 34 of the outer ring 8, the axial tip portion of the inner ring 4 enters the bearing portion 28 provided on the outer ring 8 to enter the bearing portion 28 of the inner ring 4. The axial tip comes into contact with the end plate 26 of the outer ring 8. Then, the axial tip portion of the inner ring 4 is rotatably supported by the bearing portion 28. As a result, the inner ring 4 is positioned in the axial direction inside the outer ring 8 in a rotatable state with respect to the inner ring 8.

Subsequently, the operation of the torque limiter 2 will be described with reference to FIG.
When a rotational torque larger than a predetermined value, that is, idling torque, is applied around the axis of the central axis o that relatively rotates the inner ring 4 and the outer ring 8 in a direction that loosens the winding of the coil spring 6 around the inner ring 4. The frictional force between the coil spring 6 and the inner ring 4 due to the tightening force of the coil spring 6 is overcome, and the outer ring 8 and the inner ring 4 rotate relatively. At this time, as understood by referring to the BB cross section of FIG. 1, the thin-walled portion 42 also acts as a so-called grease pocket, and the lubricant sealed inside the outer ring 8 is efficiently supplied to the coil spring 6. Will be done. On the other hand, if it is equal to or less than the idling torque, relative rotation does not occur due to the frictional force between the inner ring 4 and the coil spring 6.

Although the torque limiter 2 of the present invention has been described in detail with reference to the drawings attached above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the present invention. .. For example, in the torque limiter 2 described above, the coil spring 6 has a single hook portion 22, and the loosening direction of the coil spring 6 is limited to only one of the circumferential directions. Therefore, the torque limiter 2 is a so-called unidirectional torque. Although it was a limiter, the present invention is not limited to this form, and the present invention can be applied to, for example, Japanese Patent No. 3315603, which has been previously patented by the applicant of the present application, and the same application of the present application. It can also be applied to the bidirectional torque limiter disclosed in Japanese Patent Application Laid-Open No. 2002-155973, which was previously applied for a patent by a person. Further, in the illustrated embodiment, the inner ring 4 is connected to the external device on the input side and the outer ring 8 is connected to the external device on the output side, respectively, but the input / output relationship may be opposite.

2: Torque limiter 4: Inner ring 6: Coil spring 8: Outer ring 12: Flange part 34: Engagement part 38: Opening 40: Protruding piece 42: Thin wall part

Claims (5)

It includes an inner ring, a coil spring mounted in contact with the outer peripheral surface of the inner ring, and a tubular outer ring into which the inner ring mounted with the coil spring is inserted.
The inner ring and the outer ring have a common central axis, the inner ring is provided with an annular flange extending radially outward, and the outer ring is provided with a plurality of engaging portions extending radially inward. Be,
When the inner ring to which the coil spring is mounted is inserted inside the outer ring, the flange portion gets over the engaging portion and engages with the engaging portion in the axial direction, and the coil spring is attached to the outer ring. Engages non-rotatably against
When a rotational torque around the central axis that relatively rotates the inner ring and the outer ring is applied, when the rotational torque is larger than a predetermined value, the frictional force between the coil spring and the inner ring is applied. In a torque limiter in which the outer ring and the inner ring rotate relative to each other
The outer ring is provided with an opening that penetrates in the radial direction corresponding to the engaging portion, and inside the opening, a protruding piece that projects axially from the inner peripheral edge of the outer ring that defines the opening is provided. The torque limiter is characterized in that the engaging portion is formed on the protruding piece. The torque limiter according to claim 1, wherein a thin wall portion having a reduced radial wall thickness is formed in the circumferential angle region where the opening is formed in the outer ring. The torque limiter according to claim 1 or 2, wherein an overcoming guide means is provided on either one or both of the flange portion and the engaging portion. The torque limiter according to any one of claims 1 to 3, wherein the outer ring is provided with a bearing portion that rotatably supports the axial end portion of the inner ring. The torque limiter according to any one of claims 1 to 4, wherein a lubricant is sealed inside the outer ring.

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