JP4367761B2 - Torque limiter - Google Patents

Description

  The present invention relates to a torque limiter.

The torque limiter is installed in a power transmission mechanism to prevent transmission of excessive torque, or is incorporated in the hinge of the swing door to hold the swing door at an arbitrary opening degree. Widely used in applications.
Conventional torque limiters include, for example, a rotation input body, a rotation output body that rotates concentrically with the rotation input body, a friction plate that is disposed between the rotation input body and the rotation output body, and a friction plate that is rotated. For example, there is a coil spring configured to press contact between the body and the rotation output body and transmit torque between the rotation input body and the rotation output body (see, for example, Patent Document 1).
However, most of the torque limiters have a friction plate exposed to the outside, and dust is likely to enter the pressure contact area between the friction plate, the rotary input body, and the rotary output body, which is disadvantageous in improving durability. there were.
Therefore, in order to solve such a problem, the present applicant has already applied for a torque limiter having excellent durability (see Patent Document 2).
JP-A-7-127656 JP-A-10-213151

This earlier application is composed of an outer member, a shaft-shaped inner member housed in the outer member, a friction plate, and the like, and dust enters the press contact portion between the outer member, the inner member, and the friction plate. Although it is difficult to improve durability, a coil spring is used to press-contact the outer member, the inner member, and the friction plate, and the coil spring is disposed coaxially with the inner member and outside the inner member. In order to arrange the coil spring, a cylindrical space must be ensured coaxially with the inner member and outside the inner member, which is disadvantageous in reducing the size of the torque limiter.
The present invention has been devised in view of the above circumstances, and an object of the present invention is to provide a torque limiter that can enhance durability, and that can achieve downsizing and cost reduction.

In order to achieve the above object, the present invention limits the torque transmitted between the shaft and the member supporting the shaft or between the shaft and the member supported by the shaft to a predetermined upper limit value. A torque limiter, which includes a cylindrical body inserted into a hole formed in a member supporting the shaft or a member supported by the shaft, and an endless annular elastic member. The cylindrical body is made of synthetic resin, and a bearing surface that abuts the outer peripheral surface of the shaft is formed on the inner peripheral surface of the cylindrical body, and the outer peripheral surface of the cylindrical body extends in the circumferential direction of the cylindrical body. A concave groove is formed. A plurality of slits extending in the longitudinal direction of the cylindrical body are formed at intervals in the circumferential direction of the cylindrical body, thereby forming a plurality of pieces extending in the longitudinal direction of the cylindrical body. Adjacent pieces are interconnected at their ends. The bearing surface is divided in the circumferential direction of the cylindrical body by the plurality of slits, and individual portions of the divided bearing surface are formed in the plurality of pieces, respectively, whereby the shaft is The bearing surface is configured to expand in diameter by being inserted into the cylindrical body. The endless annular elastic member is fitted into the groove of the serial cylinder, are crushed in the radial direction of the tubular member by the inner peripheral surface of the hole and the bottom surface of the groove, the crushed The cylinder is crushed so that the groove is not completely filled with the crushed endless annular elastic member, and the cylinders pressed against each other by the elastic force exerted by the crushed endless annular elastic member The upper limit value of the torque transmitted between the shaft and the cylindrical body is determined by the frictional force acting between the bearing surface of the shaft and the outer peripheral surface of the shaft.

The present invention does not require a coil spring that cannot be disposed unless a large space is secured in the axial direction as in the prior art, and is composed of a cylindrical body made of synthetic resin and an endless annular elastic member. Since the endless annular elastic member has a simple structure and can be disposed in a small space, the durability of the torque limiter can be increased, and the size and cost can be reduced.
Further, the crushing margin of the endless annular elastic member can be easily changed, and the upper limit value of the transmission torque can be easily set to a desired value.

  In the present invention, a cylindrical body having a bearing surface is provided on the inner circumferential portion, and the bearing surface is formed by the elastic force of the endless annular elastic member exerted by crushing the endless annular elastic member fitted on the outer circumferential portion of the cylindrical body. The above-mentioned object was achieved by pinching the shaft through the gap.

Embodiments of the present invention will be described below with reference to the drawings.
1A is a front view of the torque limiter of the first embodiment, FIG. 1B is a sectional side view of the torque limiter, FIG. 2A is a front view of the cylinder, and FIG. 1B is a sectional side view of the cylinder. (C) has shown the side view of a cylinder.
The torque limiter 10 according to the first embodiment is interposed between the shaft 12 and the hole 16 of the case 14 through which the shaft 12 is inserted to support the shaft 12 in a non-rotatable manner. Slips between the shaft 12 and the case 14 when acting from the case 14 to the case 14 or from the case 14 to the shaft 12, allowing relative rotation between the shaft 12 and the case 14. The upper limit value of the torque transmitted between the case 12 and the case 14 is determined.
The torque limiter 10 includes a cylinder (bush) 20 inserted into the hole 16 of the case 14 and an endless annular elastic member 30.

The cylindrical body 20 is made of synthetic resin, has excellent wear resistance, has an appropriate coefficient of friction with respect to the shaft 12 so as to obtain a desired torque characteristic, and has a predetermined flexibility and rigidity and thermal expansion and contraction. Specifically, when the material of the shaft 12 is a metal such as stainless steel, a synthetic resin containing at least one of a polyamide resin, a polyolefin resin, a fluororesin, and a polyacetal resin can be used. .
The cylindrical body 20 has a bearing surface 22 formed on the inner peripheral surface. The bearing surface 22 is formed so as to be able to expand and contract in the radial direction of the cylindrical body 20, and the bearing surface 22 contacts the outer peripheral surface of the shaft 12. The shaft 12 is fitted so as to be in contact.

More specifically, as shown in FIG. 2, the outer peripheral surface excluding the middle portion (center portion) in the longitudinal direction of the cylindrical body 20 is formed as a small-diameter outer peripheral surface 2001 having a uniform diameter. Two flange portions 2002 are bulged and formed at an intermediate portion (central portion) in the longitudinal direction of the cylindrical body 20 with an interval in the longitudinal direction of the cylindrical body 20. A concave groove 2004 is formed between the two flange portions 2002, and an outer peripheral surface portion of the cylindrical body 20 located between the two flange portions 2002 is a bottom surface 2006 of the concave groove 2004. Accordingly, the cylindrical body 20 is formed with a concave groove 2004 extending on the outer peripheral surface thereof in the circumferential direction of the cylindrical body 20.
The endless annular elastic member 30 is fitted in the concave groove 2004. As will be described later, the endless annular elastic member 30 has a radius of the cylindrical body 20 between the bottom surface 2006 of the concave groove 2004 and the small-diameter inner peripheral surface 1404 of the hole 16. The endless annular elastic member 30 does not completely fill the concave groove 2004 even if the cross section is crushed into a flat shape in the longitudinal direction of the cylindrical body 20.
In addition, a large-diameter inner peripheral surface 2012 having an equal inner diameter larger than the outer diameter of the shaft 12 is formed at a location near the end in the longitudinal direction of the cylindrical body 20 on the inner peripheral surface of the cylindrical body 20, Furthermore, a conical tapered surface 2014 whose inner diameter gradually decreases from the back end of each large-diameter inner peripheral surface 2012 to the longitudinal center of the cylindrical body 20, and the bearing surface 22 has tapered surfaces on both sides thereof. It is formed between 2014. In the present embodiment, the inner peripheral surface portion of the cylindrical body 20 located on the radially inner side of the bottom surface of the concave groove 2004 is the bearing surface 22.
As shown in FIGS. 1 (A) and 2 (A), the bearing surface 22 is formed of six flat surfaces that form the sides of a regular hexagonal column when viewed from the longitudinal direction of the cylindrical body 20, and each of the bearing surfaces 22 is formed on the outer peripheral surface of the shaft 12. It is formed with a dimension that the central portion of the flat surface comes into contact with.

Further, six slits 2030 having the same shape are formed in the cylindrical body 20 at equal intervals in the circumferential direction.
Six pieces 2040 extending in the longitudinal direction of the cylindrical body 20 are formed in the cylindrical body 20 by the slits 2030, and each piece 2040 is separated at equal intervals in the circumferential direction by the slits 2030. Two flange portions 2002, a concave groove 2004, a large-diameter inner peripheral surface 2012, a tapered surface 2014, and a bearing surface 22 are formed. Therefore, the bearing surface 22 of the cylindrical body 20 is divided by the slit 2030 in the circumferential direction of the cylindrical body 20, and individual portions of the divided bearing surface 22 are formed in the plurality of pieces 2040, respectively.
These slits 2030 extend from one end in the longitudinal direction of the cylindrical body 20 to the front of the other end in the longitudinal direction, and adjacent ones 2040 are interconnected at their ends, particularly in this embodiment, The individual pieces 2040 are connected to each other at the connecting portion 2008 at the other end in the longitudinal direction of the cylindrical body 20, and the six pieces 2040 are expanded and contracted in the radial direction of the cylindrical body 20 except for the other end where the connecting portion 2008 is located. Therefore, the bearing surface 22 can be expanded and contracted in the radial direction of the cylindrical body 20.

The endless annular elastic member 30 is preferably formed of a material having elasticity and exhibiting a relatively large frictional force, such as natural rubber or synthetic rubber, and the cross-sectional shape thereof is circular, elliptical, A flat oval shape is preferable, but other cross-sectional shapes are also possible. A commercially available O-ring can be used as the endless annular elastic member 30.
The endless annular elastic member 30 is wound around the outer periphery of the cylindrical body 20 by being fitted into the concave groove 2004.
In this embodiment, the inner diameter of the endless annular elastic member 30 is smaller than the outer diameter of the bottom surface 2006 of the concave groove 2004.
In addition, the endless annular elastic member 30 is formed with a larger outer diameter than the outer diameter of the flange 2002 when fitted in the concave groove 2004.

In this embodiment, the case 14 has a cylindrical shape and is made of metal or synthetic resin.
The inner peripheral portion of the case 14 includes a large-diameter inner peripheral surface 1402, a small-diameter inner peripheral surface 1404 having a smaller inner diameter than the large-diameter inner peripheral surface 1402, and an end inner peripheral surface 1406 having a smaller inner diameter than the small-diameter inner peripheral surface 1404. Are arranged in this order in the longitudinal direction of the case 14, and the hole 16 is constituted by these inner peripheral surfaces 1402, 1404, 1406.
The small-diameter inner peripheral surface 1404 has an inner diameter that is larger than the outer diameter of the flange portion 2002 and is smaller than the outer diameter of the endless annular elastic member 30 fitted in the concave groove 2004. When the cylindrical body 20 fitted with the elastic member 30 is inserted into the hole 16, the endless annular elastic member 30 is compressed by the small diameter inner peripheral surface 1404 radially inward of the small diameter inner peripheral surface 1404. ing.
The inner circumferential surface 1406 of the end is formed with a size that the inner diameter is larger than the small-diameter outer circumferential surface 2001 of the cylindrical body 20.

The cylindrical body 20 in which the endless annular elastic member 30 is fitted in the concave groove 2004 of the cylindrical body 20 has one end of the cylindrical body 20 on the inner side of the end inner peripheral surface 1406, and the two flanges 2002 and the endless annular elastic member 30. The cylindrical body 20 is inserted into the hole 16 so that the other end of the cylinder 20 is positioned inside the large-diameter inner peripheral surface 1402 inside the small-diameter inner peripheral surface 1404, and then the cylindrical cap member 40 is inserted into the large-diameter inner peripheral surface. 1402 is fitted. And the end surface which makes the boundary of the small diameter inner peripheral surface 1404 and the edge part inner peripheral surface 1406, and the inner end surface of the cap member 40 face each outer side of the two collar parts 2002, Therefore Dropout is prevented. The cap member 40 is made of synthetic resin, and the inner peripheral surface of the cap member 40 is formed with a size larger than the small-diameter outer peripheral surface 2001 of the cylindrical body 20.
When the shaft 12 is inserted into the hole 16 of the case 14 through the bearing surface 22 of the cylindrical body 20, the shaft 12 is inserted into the cylindrical body 20 while expanding the diameter of the bearing surface 22, and the endless annular elastic member 30 has a small diameter. The tube 20 is compressed in the radial direction between the inner peripheral surface 1404 and the bottom surface 2006 of the concave groove 2004, and the cross section thereof is crushed into a flat shape in the longitudinal direction of the tube 20.

A material exhibiting a relatively large frictional force is used as the endless annular elastic member 30. Therefore, when the endless annular elastic member 30 is in a crushed state, the endless annular elastic member 30 rotates with respect to the case 14 by the frictional force acting between the endless annular elastic member 30 and the hole 16 of the case 14. The cylindrical body 20 is fixed so as not to rotate with respect to the endless annular elastic member 30 by a frictional force acting between the endless annular elastic member 30 and the concave groove 2004 of the cylindrical body 20. .
On the other hand, compared with these frictional forces, the frictional force acting between the bearing surface 22 of the cylindrical body 20 and the outer peripheral surface of the shaft 12 is relatively small. Therefore, the shaft 12 and the cylindrical body 20 are caused by the frictional force that acts between the bearing surface 22 of the cylindrical body 20 and the outer peripheral surface of the shaft 12 that are pressed against each other by the elastic force exerted by the crushed endless annular elastic member 30. The upper limit value of torque transmitted between the two is determined.
Accordingly, the crushing margin of the endless annular elastic member 20 is a crushing margin of an appropriate size such that the frictional force acting between the shaft 12 and the cylindrical body 20 becomes a desired size. The dimension of each part is designed so that the appropriate crushing allowance is obtained.

According to the first embodiment, the coil spring 20 and the endless annular elastic member 30 that are disposed inside the case 14 are not required without using a coil spring that cannot be disposed unless a large space is ensured in the axial direction as in the prior art. Since the cylindrical body 20 and the endless annular elastic member 30 are simple in structure and can be arranged in a small space, it is a matter of course that the durability of the torque limiter 10 can be improved, and the size and cost can be reduced. This is extremely advantageous.
Further, by changing the inner diameter of the endless annular elastic member 30 without changing the outer diameter of the bottom surface 2006 of the concave groove 2004, or by changing the outer diameter of the bottom surface 2006 of the concave groove 2004 without changing the inner diameter of the endless annular elastic member 30. By changing both the outer diameter of the bottom surface 2006 of the concave groove 2004 and the inner diameter of the endless annular elastic member 30, or without changing the inner diameter of the small-diameter inner peripheral surface 1404, By changing the diameter, or by changing the inner diameter of the small-diameter inner peripheral surface 1404 without changing the outer diameter of the endless annular elastic member 30, or by the inner diameter of the small-diameter inner peripheral surface 1404 and the outer diameter of the endless annular elastic member 30 By changing, the crushing margin of the endless annular elastic member 20 can be easily changed, and the upper limit value of the transmission torque can be easily set to a desired value.

Further, since the inner peripheral surface portion of the cylindrical body 20 located on the radially inner side of the bottom surface 2006 of the concave groove 2004 is the bearing surface 22, the elastic force of the endless annular elastic member 30 is transmitted through the bearing surface 22 to the shaft 12. It is advantageous for efficiently obtaining the clamping force by the endless annular elastic member 30.
Further, since the tapered surfaces 2014 are provided on both sides of the bearing surface 22, it is advantageous in smoothly inserting the shaft 12 into the bearing surface 22.
Further, while the outer peripheral surface of the shaft 12 is a cylindrical surface, the bearing surface 22 is formed of six flat surfaces forming the side faces of regular hexagonal columns as described above, and the center of each flat surface is formed on the outer peripheral surface of the shaft 12. Since the portions are in contact with each other, the contact state between the outer peripheral surface of the shaft 12 and the bearing surface 22 is stabilized, so the upper limit value of the transmission torque is set to a desired value without causing large variations. This is extremely advantageous.

In the first embodiment, the shaft 12 is supported coaxially with the small-diameter inner peripheral surface 1404 by the endless annular elastic member 30. When a large force is applied in the radial direction of the shaft 12, the endless annular elastic member 30 is used. After the member 30 is further elastically deformed, the outer peripheral surface of the flange portion 2002 hits the small-diameter inner peripheral surface 1404 and rigidly restricts the displacement of the shaft 12 in the radial direction. In this case, the shaft 12 can be obtained by applying the small-diameter outer peripheral surface 2001 of the cylindrical body 20 to the end inner peripheral surface 1406 of the hole 16, or by applying the small-diameter outer peripheral surface 2001 of the cylindrical body 20 to the inner peripheral surface of the cap member 40. The displacement in the radial direction may be rigidly restricted.
Further, in the first embodiment, the end surface that forms the boundary between the small-diameter inner peripheral surface 1404 and the end inner peripheral surface 1406 and the inner end surface of the cap member 40 face the outer sides of the two flange portions 2002, so that Although the cylindrical body 20 is prevented from dropping out of the case 12, various configurations known in the art can be adopted for such a configuration that prevents the cylindrical body 20 from dropping out of the case 12 in the axial direction. .

Table 1 shows the experimental results of the torque limiter 10 of Example 1.
In this experiment, a stainless steel shaft 12 having an outer diameter of 18.7 mm was used, and the material of the cylindrical body 20 was a polyacetal resin. Then, using an endless annular elastic member 30 having a circular cross-sectional diameter of 2.4 mm, the relationship between the crushing margin of the endless annular elastic member 30 and the rotational torque when slipping occurred was examined. Here, the crushing allowance means that when the crushing allowance is Δt, the endless annular elastic member 30 is crushed by Δt over the entire circumference, and the outer diameter of the endless annular elastic member 30 is reduced by 2 × Δt. (Or the inner diameter of the endless annular elastic member 30 is increased by 2 × Δt).
The endless annular elastic member 30 was made of two types, one made of NBR (nitrile butadiene rubber) and the other made of silicon rubber.
As is apparent from Table 1, the upper limit value of torque at the time of causing slippage, that is, the transmission torque is desired by changing the crushing margin of the endless annular elastic member 30 or by selecting the material of the endless annular elastic member 30. It is clear that the value can be set.

Next, Example 2 will be described.
3 is a cross-sectional side view of the torque limiter according to the second embodiment, FIG. 4A is a front view of the cylindrical body, and FIG. 3B is a cross-sectional side view of the cylindrical body.
The second embodiment is different from the first embodiment in that two endless annular elastic members 30 are used and the slits 2030 are alternately extended in opposite directions. The different points will be described mainly with the same reference numerals.
Similar to the first embodiment, the torque limiter 10A according to the second embodiment determines an upper limit value of the torque transmitted between the shaft 12 and the case 14A. The torque limiter 10A is disposed in the hole 16 of the case 14A. A cylindrical body 20A made of synthetic resin and two endless annular elastic members 30 are provided.
The cylindrical body 20A has a bearing surface 22 formed on the inner peripheral surface. The bearing surface 22 is formed so as to be expandable / contractable in the radial direction of the cylindrical body 20A, and the bearing surface 22 contacts the outer peripheral surface of the shaft 12. The shaft 12 is fitted so as to be in contact.

As shown in FIG. 4, the outer peripheral surface of the cylindrical body 20 </ b> A is formed as a small-diameter outer peripheral surface 2001 having a uniform diameter except for the intermediate portion (central portion) in the longitudinal direction, and the longitudinal intermediate portion of the cylindrical body 20 </ b> A. At the (center) portion, three flanges 2002 are bulged and formed at intervals in the longitudinal direction of the cylindrical body 20A. Two concave grooves 2004 are formed between the three flange portions 2002, and an outer peripheral surface portion of the cylindrical body 20 </ b> A located between the three flange portions 2002 is a bottom surface 2006 of the concave groove 2004. In addition, the outer diameter of the collar part 2002 located in the center among the three collar parts 2002 is smaller than the outer diameter of the collar part 2002 located on both sides. Accordingly, the cylindrical body 20A is formed with two concave grooves 2004 extending on the outer peripheral surface thereof in the circumferential direction of the cylindrical body 20A.
The two endless annular elastic members 30 are fitted in the respective concave grooves 2004, and the endless annular elastic member 30 is disposed between the bottom surface 2006 of the concave groove 2004 and the small-diameter inner peripheral surface 1404 of the hole portion 16 in the radial direction of the cylindrical body 20A. The endless annular elastic member 30 does not completely fill the concave groove 2004 even if the cross section is compressed and flattened into a flat shape in the longitudinal direction of the cylindrical body 20A.
Further, the inner peripheral surface of the cylindrical body 20A is formed with a large-diameter inner peripheral surface 2012 having an equal inner diameter larger than the outer diameter of the shaft 12 at a location near the end in the longitudinal direction. A conical tapered surface 2014 whose inner diameter gradually decreases from the back end of the large-diameter inner peripheral surface 2012 to the central portion in the longitudinal direction of the cylindrical body 20A is formed, and the bearing surface 22 is between the tapered surfaces 2014 on both sides. Is formed. In the present embodiment, the inner peripheral surface portion of the cylindrical body 20 </ b> A located on the radially inner side of the bottom surface of each concave groove 2004 is the bearing surface 22.
As shown in FIG. 4A, the bearing surface 22 is formed of six flat surfaces that form the side surfaces of a regular hexagonal column when viewed from the longitudinal direction of the cylinder 20A, and the central portion of each flat surface is formed on the outer peripheral surface of the shaft 12. It is formed with the dimension which contacts.

Further, six slits 2030 having the same shape are formed in the cylindrical body 20A at equal intervals in the circumferential direction.
The slits 2030 extend from one end in the longitudinal direction of the cylinder 20A to the front of the other end in the longitudinal direction, and extend from the other end in the longitudinal direction of the cylinder 20 to the front of one end in the longitudinal direction. Are provided alternately in the circumferential direction, and six pieces 2040 extending in the longitudinal direction of the cylinder 20A are formed in the cylinder 20A by the slits 2030, and each piece 2040 is provided by the slit 2030. Two flange portions 2002, two concave grooves 2004, a large-diameter inner peripheral surface 2012, a tapered surface 2014, and a bearing surface 22 that are separated at equal intervals in the circumferential direction are formed, respectively. The body 20A can be enlarged or reduced in the radial direction. Accordingly, the bearing surface 22 of the cylindrical body 20A is divided in the circumferential direction of the cylindrical body 20A by the slits 2030, and individual portions of the divided bearing surface 22 are formed in the plurality of pieces 2040, respectively. Adjacent pieces 2040 are interconnected at their ends, and particularly in this embodiment, the plurality of pieces 2040 are alternately interconnected at one end and the other end in the longitudinal direction of the cylinder 20A. is doing.

The two endless annular elastic members 30 are the same, and are wound around the outer circumference of the cylindrical body 20A by being fitted into the respective concave grooves 2004.
In this embodiment, the inner diameter of the endless annular elastic member 30 is smaller than the outer diameter of the bottom surface 2006 of the concave groove 2004.
In addition, the endless annular elastic member 30 is formed with a larger outer diameter than the outer diameter of the flange 2002 when fitted in the concave groove 2004.

The case 14 </ b> A has a cylindrical shape, and an inner peripheral portion thereof has a large-diameter inner peripheral surface 1402, a small-diameter inner peripheral surface 1404 having an inner diameter smaller than that of the large-diameter inner peripheral surface 1402, and an inner diameter larger than that of the small-diameter inner peripheral surface 1404. A small end inner peripheral surface 1406 is formed by being arranged in this order in the longitudinal direction of the case 14 </ b> A, and the hole 16 is constituted by these inner peripheral surfaces 1402, 1404, 1406.
The small-diameter inner peripheral surface 1404 is formed with a size whose inner diameter is larger than the outer diameter of the flange portion 2002 and smaller than the outer diameter of the endless annular elastic member 30 fitted in each concave groove 2004, When the cylindrical body 20A fitted with the two endless annular elastic members 30 is inserted into the holes 16, the endless annular elastic members 30 are compressed radially inward of the small diameter inner peripheral surface 1404 by the small diameter inner peripheral surface 1404. It is formed to do.
The end inner peripheral surface 1406 has an inner diameter larger than that of the small-diameter outer peripheral surface 2001 of the cylindrical body 20A.

The cylindrical body 20A in which the endless annular elastic member 30 is fitted in the concave groove 2004 of the cylindrical body 20A is inserted into the hole 16, and then the cap member 40A is fitted into the large-diameter inner peripheral surface 1402. The cap member 40 </ b> A includes an annular plate portion 4002 that closes an end surface of the large-diameter inner peripheral surface 1402 and a cylindrical portion 4004 that is fitted to the large-diameter inner peripheral surface 1402. Then, the end surface that forms the boundary between the small-diameter inner peripheral surface 1404 and the end inner peripheral surface 1406 and the end surface of the cylindrical portion 4004 of the cap member 40A face the outer sides of the flange portions 2002 on both sides. The dropout of the body 20A is prevented.
When the shaft 12 is inserted into the hole 16 of the case 14A through the bearing surface 22 of the cylindrical body 20A, the shaft 12 is inserted into the cylindrical body 20A while expanding the diameter of the bearing surface 22, and the two endless annular elastic members 30 are inserted. Is compressed in the radial direction of the cylindrical body 20A between the small-diameter inner peripheral surface 1404 and the bottom surface 2006 of each concave groove 2004, and the cross section thereof is crushed into a flat shape in the longitudinal direction of the cylindrical body 20A.

According to the second embodiment, as in the first embodiment, it is obvious that the durability of the torque limiter 10 can be increased, which is extremely advantageous in terms of downsizing and cost reduction. Further, the crushing allowance of the endless annular elastic member 20 can be easily changed, and the upper limit value of the transmission torque can be easily set to a desired value. Further, since the inner peripheral surface portion of the cylindrical body 20 located on the inner side in the radial direction of the bottom surface 2006 of the two concave grooves 2004 is the bearing surface 22, the elastic force of the endless annular elastic member 30 is passed through the bearing surface 22. This is directly transmitted to the shaft 12 and is advantageous in efficiently obtaining the clamping force by the endless annular elastic member 30. Further, since the tapered surfaces 2014 are provided on both sides of the bearing surface 22, it is advantageous in smoothly inserting the shaft 12 into the bearing surface 22. Further, since the central portion of each bearing surface 22 that is a flat surface comes into contact with the outer peripheral surface that is the cylindrical surface of the shaft 12, the contact state between the outer peripheral surface of the shaft 12 and the bearing surface 22 is stabilized, and the transmission torque This is extremely advantageous in setting the upper limit value to a desired value without causing a large variation.
Further, in the second embodiment, since the two endless annular elastic members 20 are disposed so as to be located radially outward on both sides of the bearing surface 22 along the longitudinal direction of the shaft 12A, the elasticity of the two endless annular elastic members 20 is determined. The force is uniformly transmitted along the longitudinal direction of the shaft 12A with respect to the bearing surface 22. Therefore, the shaft 12A can be clamped more stably, which is advantageous in obtaining a stable upper limit value of the transmission torque.

Next, Example 3 will be described.
FIG. 5A shows a front view of a cylindrical body constituting the torque limiter of the third embodiment.
In the third embodiment, only the shape of the bearing surface 22B in the cylindrical body 20B is different from the second embodiment.
In the second embodiment, the bearing surface 22 is a flat surface, whereas in the third embodiment, the bearing surface 22B is formed as a convex cylindrical surface on the radially inner side of the cylindrical body 20B.
Even with such a cylindrical bearing surface 22B, the contact state between the outer peripheral surface of the shaft 12 and the bearing surface 22B is stable, and the upper limit value of the transmission torque is set to a desired value without causing large variations. This is extremely advantageous.

Next, Example 4 will be described.
FIG. 5B shows a front view of a cylinder constituting the torque limiter of the fourth embodiment.
Also in the fourth embodiment, only the shape of the bearing surface 22C in the cylindrical body 20C is different from the second embodiment.
In the fourth embodiment, the bearing surface 22 </ b> C is formed as a cylindrical surface convex outward in the radial direction of the cylindrical body 20 </ b> C, and the radius of the cylindrical surface is larger than the radius of the shaft 12.
Even with such a cylindrical bearing surface 22C, the contact state between the outer peripheral surface of the shaft 12 and the bearing surface 22C is stable, and the upper limit value of the transmission torque is set to a desired value without causing large variations. This is extremely advantageous.

Next, Example 5 will be described.
FIG. 5C shows a front view of a cylinder constituting the torque limiter of the fifth embodiment.
Also in the fifth embodiment, only the shape of the bearing surface 22D in the cylindrical body 20D is different from the second embodiment.
In the fifth embodiment, the bearing surface 22D is formed as a cylindrical surface convex outward in the radial direction of the cylindrical body 20D, and the radius of this cylindrical surface is formed with a dimension substantially the same as the radius of the shaft 12.
Also with such a cylindrical bearing surface 22D, the upper limit value of the transmission torque can be set to a desired value.

In addition, although the above example demonstrated the case where the bearing surface 22 was formed only in the center part of the longitudinal direction of the cylinder 20, the formation location of the bearing surface 22 is the cylinder 20 on the internal peripheral surface of the cylinder 20. The bearing surface 22 may be formed over the entire length in the longitudinal direction of the cylindrical body 20 at the inner peripheral portion of the cylindrical body 20. In this case, a concave portion that is continuous in the circumferential direction is provided at 22 locations on the bearing surface 22 of the cylindrical body 20 at the center in the longitudinal direction of the cylindrical body 20 so that the bearing surface 22 is divided in the longitudinal direction of the cylindrical body 20. Good .

It is explanatory drawing of the torque limiter of Example 1. FIG. It is explanatory drawing of the cylinder which comprises the torque limiter of Example 1. FIG. It is a cross-sectional side view of the torque limiter of the second embodiment. It is explanatory drawing of the cylinder which comprises the torque limiter of Example 2. FIG. It is explanatory drawing of the cylinder which comprises the torque limiter of Example 3,4,5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10A ... Torque limiter, 12 ... Shaft, 14, 14A ... Case, 20, 20A, 20B, 20C, 20D ... Cylindrical body, 22 ... Bearing surface, 30 ... Endless annular elastic member.

Claims (9)

A torque limiter for limiting a torque transmitted between a shaft and a member supporting the shaft or between a shaft and a member supported by the shaft to a predetermined upper limit;
A cylindrical body inserted into a hole formed in a member that supports the shaft or a member supported by the shaft, and an endless annular elastic member;
The cylindrical body is made of synthetic resin, and a bearing surface that abuts the outer peripheral surface of the shaft is formed on the inner peripheral surface of the cylindrical body, and the outer peripheral surface of the cylindrical body extends in the circumferential direction of the cylindrical body. A concave groove is formed,
A plurality of slits extending in the longitudinal direction of the cylindrical body are formed at intervals in the circumferential direction of the cylindrical body, thereby forming a plurality of pieces extending in the longitudinal direction of the cylindrical body. The adjacent halves are interconnected at their ends,
The bearing surface is divided in the circumferential direction of the cylindrical body by the plurality of slits, and individual portions of the divided bearing surface are formed in the plurality of pieces, respectively, whereby the shaft is The bearing surface is configured to expand in diameter by being inserted into the cylindrical body,
The endless annular elastic member is fitted into the groove of the cylindrical body, are crushed in the radial direction of the tubular member by the inner peripheral surface of the hole and the bottom surface of the groove, the crushed The cylinder is crushed so that the groove is not completely filled with the crushed endless annular elastic member, and the cylinders pressed against each other by the elastic force exerted by the crushed endless annular elastic member The upper limit value of the torque transmitted between the shaft and the cylindrical body is determined by the frictional force acting between the bearing surface of the shaft and the outer peripheral surface of the shaft.
Torque limiter characterized by that. The plurality of slits of the cylindrical body are formed so as to extend from one end in the longitudinal direction of the cylindrical body to the front of the other end, and the plurality of pieces of the cylindrical body are formed in a longitudinal direction of the cylindrical body. The torque limiter according to claim 1, wherein the torque limiter is interconnected at the other end in the direction. The plurality of slits of the cylindrical body include a slit extending from one end in the longitudinal direction of the cylindrical body to the front of the other end, and a slit extending from the other end in the longitudinal direction of the cylindrical body to the front of the one end. 2. The torque limiter according to claim 1, wherein the plurality of pieces of the cylindrical body are alternately formed and are interconnected alternately at one end and the other end in the longitudinal direction of the cylindrical body. . Individual parts of the bearing surface which is divided by the plurality of slits, flat surface, or a convex cylindrical surface radially inwardly of the cylindrical body, or, in a radius of a dimension greater than the radius of said shaft The torque limiter according to any one of claims 1 to 3, wherein the torque limiter is formed of a cylindrical surface convex outward in the radial direction of the cylindrical body. The bearing surface of the inner peripheral surface of the cylindrical body, the torque limiter according to claim 4, wherein it has been found provided in an intermediate portion in the longitudinal direction of the tubular member. The inner peripheral surface of the cylindrical body, on both sides of the bearing surface in the longitudinal direction of the tubular body, wherein, wherein the gradually tapered surface whose inner diameter increases with increasing distance from the bearing surface are formed Item 6. The torque limiter according to Item 5 . A large-diameter inner peripheral surface having an inner diameter larger than the outer diameter of the shaft is formed on the inner peripheral surface of the cylindrical body on the outer side of the tapered surface in the longitudinal direction of the cylindrical body. The torque limiter according to claim 6 . The endless annular elastic member and any one torque limiter according to claims 1 to 7 wherein the groove is characterized by being plurality et al. 9. The shaft according to claim 1, wherein the shaft is made of metal, and the cylindrical body is made of a synthetic resin selected from the group consisting of polyamide resin, polyolefin resin, fluororesin, and polyacetal resin. The torque limiter described in the item.

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