Overload protection device

Abstract

To provide an overload protection device that has a simple structure, enables low processing cost, can increase transmission torque, can enhance accuracy of set allowable torque and can be used continuously if returning to normal toque even when becoming an overload state.SOLUTION: An overload protection device 100 can block transmission of torque greater than an allowable range of an inner rotary member 120 and an outer rotary member 110 that are provided coaxially to enable relative rotation. The overload protection device includes: an inner ring 130 having an inner peripheral transmission surface 133 coming into contact with an outer peripheral surface of the inner rotary member 120 and a first tapered surface 131; and an outer ring 140 having an outer peripheral transmission surface 143 coming into contact with an inner peripheral surface of the outer rotary member 110 and a second tapered surface 141 coming into contact with the first tapered surface 131 of the inner ring 130. The inner ring 130 and the outer ring 140 can be pressed so as to come close to each other in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inner rotating member and an outer rotating member that are coaxially arranged so as to be rotatable relative to each other, and to an overload protection device that transmits torque between the inner rotating member and the outer rotating member and can block the transmission of torque that exceeds an allowable limit. [Background technology]

[0002] 2. Description of the Related Art When torque is transmitted between two shafts, an overload protection device capable of cutting off transmission of torque in the event of a torque exceeding an allowable limit is well known. For example, a known device has a configuration similar to that of a friction plate type face clutch, which transmits torque by static friction force due to pressing pressure, and by appropriately setting the pressing pressure, it responds by slipping in the event of an overload.Also known is an overload protection device, as disclosed in Patent Document 1, which transmits torque between an inner rotating member and an outer rotating member that are coaxially arranged so as to be rotatable relative to each other, and can cut off the transmission of torque when the torque exceeds the allowable limit.

[0003] The overload protection device described in Patent Document 1 is configured such that a plurality of concave arc-shaped engaging portions (221) are provided on the inner peripheral surface of the outer rotating member (second main body 20), and torque is transmitted by forcing the driving member (30) from the inner rotating member (first main body 10) toward the outer peripheral side, thereby pressing it against the engaging portions (221), and when torque exceeds the allowable limit, the driving member (30) moves toward the inner rotating member against the forcing force, thereby blocking the transmission of torque. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7006664 Summary of the Invention [Problem to be solved by the invention]

[0005] Those with a similar configuration to well-known face clutches, etc., require a large pressing pressure to transmit torque, and when tightening with a bolt, etc., even a slight difference in tightening force can cause a large change in the torque at which slippage begins, making it difficult to set the exact breaking torque. Furthermore, the overload protection device described in Patent Document 1 is configured with a torque transmission mechanism between an inner rotating member and an outer rotating member, which allows for miniaturization, but there is a problem in that both the inner rotating member and the outer rotating member have complex shapes, which increases the processing costs. Furthermore, since there is only one torque transmission point on the circumference, it is not possible to provide a maximum of more torque transmission points than the number of the engagement portions (221), making it difficult to increase the transmission torque. Furthermore, there are limitations on the pressing force of the elastic member that biases the drive member (30), making it difficult to increase the transmitted torque. In addition, since the elastic member applies a large pressing pressure with a short stroke in a small space, there are problems in that it is difficult to set the allowable torque with high precision.

[0006] To obtain a large transmission torque, it is conceivable to use the limit of allowable torque of a typical cam-type one-way clutch as an overload protection device. However, when the cam clutch exceeds the limit of the allowable torque, the torque transmission remains cut off and it is not possible to return to a torque transmission state. Therefore, although it can be used as an overload protection device in an emergency, there is a problem in that it cannot be applied to applications where it can be used continuously once the torque returns to normal even after an overload state.

[0007] The present invention aims to solve these problems by providing an overload protection device that has a simple structure, requires low processing costs, can increase the transmission torque, has high accuracy in setting the allowable torque, and can be used continuously even if an overload occurs as long as the torque returns to normal. [Means for solving the problem]

[0008] The present invention provides an overload protection device that transmits torque between an inner rotating member and an outer rotating member that are arranged coaxially and rotatable relative to each other, and that can cut off the transmission of torque when the torque exceeds an allowable limit, the overload protection device comprising an inner ring, an outer ring, and a torque adjustment mechanism, wherein the inner ring has an inner peripheral transmission surface that contacts the outer peripheral surface of the inner rotating member and a first tapered surface on the outer peripheral side, the outer ring has an outer peripheral transmission surface that contacts the inner peripheral surface of the outer rotating member and a second tapered surface that contacts the first tapered surface of the inner ring, the inner ring and the outer ring are configured to be inserted between the inner rotating member and the outer rotating member with the first tapered surface and the second tapered surface in contact, and the torque adjustment mechanism is configured to be able to press the inner ring and the outer ring so as to bring them closer to each other in the axial direction, thereby solving the above-mentioned problem. [Effects of the Invention]

[0009] According to the invention of claim 1, the inner ring and the outer ring are inserted between the inner rotating member and the outer rotating member with the first tapered surface and the second tapered surface in contact, and the inner ring and the outer ring are configured to be able to be pressed together in the axial direction, thereby making it possible to transmit a large torque by the wedge effect. Furthermore, the structure is simple, the processing costs are low, and even if an overload occurs, it can be used continuously as long as the torque returns to normal, and a constant torque can be transmitted even during an overload. Furthermore, since a large axial pressing stroke can be secured, it is possible to increase the precision of the set allowable torque.

[0010] According to the configuration of claim 2, the torque adjustment mechanism includes a female threaded hole provided in the axial direction in the outer ring, a screw through hole provided in the inner link, and a screw member that passes through the screw through hole and screws into the female threaded hole, thereby reducing the number of components and resulting in a simpler structure. According to the configuration described in claim 3, by providing a pressing member that presses the inner ring and / or the outer ring toward the regulating portion, the gap between the inner rotating member and the outer rotating member can be reduced, and the inner ring and the outer ring can be made smaller, enabling miniaturization in the radial direction. According to the configuration described in claim 4, by setting the static friction force between the inner peripheral transmission surface of the inner ring and the outer peripheral surface of the inner rotating member to be smaller than the static friction force between the outer peripheral transmission surface of the outer ring and the inner peripheral surface of the outer rotating member, the slipping surface can be specified when the allowable torque is exceeded, and the allowable torque can be set more accurately. According to the configurations described in claims 5 - 7, it is possible to suppress the damage to each surface when slipping occurs beyond the allowable torque, and continuous use is possible even after returning to the normal torque. In addition, it is possible to suppress sticking in the long - term close - contact state (temporal change of the allowable torque) and the generation of noise when slipping.

Brief Description of the Drawings

[0011] [Figure 1] Partial cross - sectional side view of the overload protection device according to the first embodiment of the present invention. [Figure 2] Perspective view of the inner ring and the outer ring in FIG. 1. [Figure 3] Exploded perspective view of the inner ring and the outer ring in FIG. 1. [Figure 4] Partial cross - sectional side view of the overload protection device according to the second embodiment of the present invention. [Figure 5] Exploded perspective view of the inner ring and the outer ring in FIG. 4 (FIG. 6). [Figure 6] Partial cross - sectional side view of the overload protection device according to the third embodiment of the present invention.

Modes for Carrying Out the Invention

[0012] Examples of the present invention will be described with reference to FIGS. 1 to 6. However, the present invention is not limited to these embodiments.

Examples

[0013] As shown in Figure 1-3, the overload protection device 100 according to the first embodiment of the present invention comprises an inner rotating member 120 and an outer rotating member 110 that are coaxially arranged so as to be rotatable relative to each other, and an inner ring 130 and an outer ring 140 that transmit torque between the inner rotating member 120 and the outer rotating member 110. The outer peripheral surface of the inner rotating member 120, the inner peripheral surface of the outer rotating member 110, the inner peripheral surface of the inner ring 130, and the outer peripheral surface of the outer ring 140 are all cylindrical. The inner ring 130 has an inner peripheral transmission surface 133 that comes into contact with the outer peripheral surface of the inner rotating member 120, and a first tapered surface 131 on the outer peripheral side. The outer ring 140 has an outer peripheral transmission surface 143 that contacts the inner peripheral surface of the outer rotating member 110 , and a second tapered surface 141 that contacts the first tapered surface 131 of the inner ring 130 . The inner ring 130 and the outer ring 140 are configured to be inserted between the inner rotating member 120 and the outer rotating member 110 with the first tapered surface 131 and the second tapered surface 141 in contact with each other.

[0014] The outer ring 140 has a female threaded hole 142 in the axial direction, and the inner link 130 has a screw through hole 132. When the screw member 150 is passed through the screw through hole 132 and screwed into the female threaded hole 142 and tightened, the inner ring 130 and the outer ring 140 are pressed toward each other in the axial direction, and a force is applied by the first tapered surface 131 and the second tapered surface 141 in a direction that spreads the gap between the outer peripheral surface of the inner rotating member 120 and the inner peripheral surface of the outer rotating member 110, making it possible to transmit torque by the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120 and the static friction force between the outer peripheral transmission surface 143 and the inner peripheral surface of the outer rotating member 110.

[0015] In this embodiment, when the screw member 150 is tightened, the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120 is smaller than the static friction force between the outer peripheral transmission surface 143 of the outer ring 140 and the inner peripheral surface of the outer rotating member 110. In addition, in this embodiment, the surface of the inner peripheral transmission surface 133 of the inner ring 130 is coated with a high-hardness material such as VC, CrN, DLC, etc., which provides excellent wear resistance and durability, and the hard and smooth surface provides a stable coefficient of friction. As a result, when the rotation transmission is interrupted by torque exceeding the allowable limit, the inner peripheral transmission surface 133 of the inner ring 130, which has excellent wear resistance and durability, always slips, making it possible to stably maintain the allowable torque even if the number of operations increases. In addition, the relationship between the tightening amount of the screw member 150 and the allowable torque (the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120) is also stabilized, making it possible to accurately set the allowable torque. The surface hardness is preferably HV1500 or more.

[0016] As shown in Figures 4 and 5, the overload protection device 100b according to the second embodiment of the present invention comprises an inner rotating member 120 and an outer rotating member 110b that are coaxially arranged so as to be rotatable relative to each other, an inner ring 130b and an outer ring 140b that transmit torque between the inner rotating member 120 and the outer rotating member 110b, and a pressure member 160 that presses the outer ring 140b in the axial direction. The outer peripheral surface of the inner rotating member 120, the inner peripheral surface of the outer rotating member 110b, the inner peripheral surface of the inner ring 130b, and the outer peripheral surface of the outer ring 140b are all cylindrical. Further, a restricting portion 112 that restricts the axial movement of the inner ring 130b is provided on the inner periphery of the outer rotating member 110b. The inner ring 130b has an inner peripheral transmission surface 133 that comes into contact with the outer peripheral surface of the inner rotating member 120, and a first tapered surface 131 on the outer peripheral side. The outer ring 140b has an outer peripheral transmission surface 143 that contacts the inner peripheral surface of the outer rotating member 110b, and a second tapered surface 141 that contacts the first tapered surface 131 of the inner ring 130b. The inner ring 130b and the outer ring 140b are configured to be inserted between the inner rotating member 120 and the outer rotating member 110b with the first tapered surface 131 and the second tapered surface 141 in contact with each other.

[0017] The pressure member 160 is provided with a screw through hole 161 and is configured to be able to axially press the outer ring 140b inserted between the inner rotation member 120 and the outer rotation member 110b by loosely fitting the inner rotation member 120. The outer rotating member 110b has a female threaded hole 111 in the axial direction, and when the screw member 150 is passed through the screw through hole 161 of the pressure member 160 and screwed into the female threaded hole 111 and tightened, the pressure member 160 and the regulating portion 112 of the outer rotating member 110b press the inner ring 130b and the outer ring 140b so that they approach each other in the axial direction, and the first tapered surface 131 and the second tapered surface 141 apply a force in a direction that spreads the gap between the outer peripheral surface of the inner rotating member 120 and the inner peripheral surface of the outer rotating member 110, making it possible to transmit torque by the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120b, the static friction force between the first tapered surface 131 and the second tapered surface 141, and the static friction force between the outer peripheral transmission surface 143 and the inner peripheral surface of the outer rotating member 110b.

[0018] In this embodiment, when the screw member 150 is tightened, the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120 is smaller than the static friction force between the outer peripheral transmission surface 143 of the outer ring 140b and the inner peripheral surface of the outer rotating member 110b and the static friction force between the first tapered surface 131 and the second tapered surface 141. Also in this embodiment, the surface of the inner peripheral transmission surface 133 of the inner ring 130b is coated with a high-hardness material such as VC, CrN, or DLC, which provides excellent wear resistance and durability, and the hard and smooth surface provides a stable coefficient of friction. As a result, when the rotation transmission is interrupted by torque exceeding the allowable limit, the inner peripheral transmission surface 133 of the inner ring 130b, which has excellent wear resistance and durability, always slips, making it possible to stably maintain the allowable torque even if the number of operations increases. In addition, the relationship between the tightening amount of the screw member 150 and the allowable torque (the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120) is also stabilized, making it possible to accurately set the allowable torque. In this embodiment, since both the inner ring 130b and the outer ring 140b can be made thin, no slits are provided for deformation, but a slit may be provided at one location on the circumference, as with the inner ring 130 and outer ring 140 in the first embodiment.

[0019] As shown in Figures 5 and 6, the overload protection device 100c according to the third embodiment of the present invention comprises an inner rotating member 120c and an outer rotating member 110c that are coaxially arranged so as to be rotatable relative to each other, an inner ring 130c and an outer ring 140c that transmit torque between the inner rotating member 120c and the outer rotating member 110c, and a pressure member 160c that presses the outer ring 140c in the axial direction. The outer peripheral surface of the inner rotating member 120c, the inner peripheral surface of the outer rotating member 110c, the inner peripheral surface of the inner ring 130c, and the outer peripheral surface of the outer ring 140c are all cylindrical. In addition, a restricting portion 112 that restricts axial movement of the outer ring 140c is provided on the inner circumference of the outer rotating member 110c, and the movement of the outer rotating member 110c relative to the inner rotating member 120c in the pressing direction of the pressure member 160c, which will be described later, is restricted. The inner ring 130c has an inner peripheral transmission surface 133 with which the inner rotating member 120c comes into contact with the outer peripheral surface, and a first tapered surface 131 on the outer peripheral side. The outer ring 140c has an outer peripheral transmission surface 143 that contacts the inner peripheral surface of the outer rotating member 110c, and a second tapered surface 141 that contacts the first tapered surface 131 of the inner ring 130c. The inner ring 130c and the outer ring 140c are configured to be inserted between the inner rotating member 120c and the outer rotating member 110c with the first tapered surface 131 and the second tapered surface 141 in contact with each other.

[0020] The pressure member 160c is provided with a screw through hole 161, and is configured to be able to axially press the outer ring 140c inserted between the inner rotation member 120c and the outer rotation member 110c by loosely fitting the inner rotation member 120c. The inner rotation member 120c is provided with a female screw hole 121 in the axial direction, and by passing a screw member 150 through a screw through-hole 161 of the pressure member 160c and screwing it into the female screw hole 121 and tightening it, the inner ring 130c and the outer ring 140c are pressed so as to approach each other in the axial direction by a restricting portion 112 of the outer rotation member 110c, which restricts the movement of the pressure member 160c in the pressing direction relative to the pressure member 160c and the inner rotation member 120c. When the inner circumferential surface of the inner rotating member 120c is compressed, a force is applied by the first tapered surface 131 and the second tapered surface 141 in a direction that pushes apart the gap between the outer circumferential surface of the inner rotating member 120c and the inner circumferential surface of the outer rotating member 110c, and torque can be transmitted by static friction forces between the inner circumferential transmission surface 133 and the outer circumferential surface of the inner rotating member 120c, static friction forces between the first tapered surface 131 and the second tapered surface 141, and static friction forces between the outer circumferential transmission surface 143 and the inner circumferential surface of the outer rotating member 110b.

[0021] In this embodiment, as in the second embodiment, when the screw member 150 is tightened, the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120c is smaller than the static friction force between the outer peripheral transmission surface 143 of the outer ring 140c and the inner peripheral surface of the outer rotating member 110c and the static friction force between the first tapered surface 131 and the second tapered surface 141. Also in this embodiment, the surface of the inner peripheral transmission surface 133 of the inner ring 130c is coated with a high-hardness material such as VC, CrN, DLC, etc., which provides excellent wear resistance and durability, and the hard and smooth surface provides a stable coefficient of friction. As a result, when the rotation transmission is interrupted by torque exceeding the allowable limit, the inner peripheral transmission surface 133 of the inner ring 130c, which has excellent wear resistance and durability, always slips, making it possible to stably maintain the allowable torque even if the number of operations increases. In addition, the relationship between the tightening amount of the screw member 150 and the allowable torque (the static friction force between the inner peripheral transmission surface 133 and the outer peripheral surface of the inner rotating member 120c) is also stabilized, making it possible to accurately set the allowable torque. In this embodiment, if the allowable torque is exceeded, the contact area between the outer ring 140c and the pressure member 160 will also slip. However, since the axial pressing force at this contact area is smaller than the radial pressing force on other surfaces and the static friction force is small, this does not pose a problem in setting the allowable torque.

[0022] In each of the above embodiments, the allowable torque during use may be set by using a torque wrench or the like to set the tightening torque. In addition, the allowable torque during use may be controlled by the rotation angle of the screw member 150, and if there is a gap between the pressure member 160 and the outer rotating member 110b, and between the pressure member 160c and the inner rotating member 120c as in the second and third embodiments, it may be controlled by this gap, or the specified allowable torque may be set by tightening until the gap disappears.

[0023] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design modifications can be made without departing from the present invention as set forth in the claims. For example, instead of the screw hole in each embodiment, a screw shaft may be protruded and a nut member may be screwed onto it. Furthermore, as a mechanism for moving the pressure member in the pressing direction, the pressure member itself may be directly threadedly engaged with the inner or outer rotating member so as to be movable in the axial direction. [Explanation of symbols]

[0024] 100... Overload protection device 110... Outer rotating member 111 Female thread hole 112 Regulatory Department 120 Inner rotating member 121 Female thread hole 130 Inner ring 131 First tapered surface 132 Screw through hole 133 Inner peripheral transmission surface 140 Outer ring 141 Second tapered surface 142 Female thread hole 143 Peripheral transmission surface 150 ··· Screw member 160 Pressure member 161 Screw through hole

Claims

1. An overload protection device that transmits torque between an inner rotating member and an outer rotating member that are coaxially arranged so as to be rotatable relative to each other, and that can block the transmission of torque when torque exceeds an allowable limit, The torque adjusting mechanism includes an inner ring, an outer ring, and a torque adjusting mechanism. the inner ring has an inner peripheral transmission surface that contacts the outer peripheral surface of the inner rotating member, and a first tapered surface on the outer peripheral side, the outer ring has an outer peripheral transmission surface that contacts the inner peripheral surface of the outer rotating member, and a second tapered surface that contacts the first tapered surface of the inner ring, the inner ring and the outer ring are configured to be inserted between the inner rotating member and the outer rotating member with the first tapered surface and the second tapered surface in contact with each other, The overload protection device is characterized in that the torque adjustment mechanism is configured to be able to press the inner ring and the outer ring so as to bring them closer to each other in the axial direction.

2. 2. The overload protection device according to claim 1, wherein the torque adjustment mechanism includes a female threaded hole axially provided in the outer ring, a threaded through hole provided in the inner link, and a screw member that passes through the threaded through hole and screws into the female threaded hole.

3. 2. The overload protection device according to claim 1, wherein the torque adjustment mechanism includes a regulating portion provided on the inner rotating member and / or the outer rotating member to regulate axial movement of the inner ring and / or the outer ring, a pressure member that presses the inner ring and / or the outer ring toward the regulating portion, a female threaded hole provided in the axial direction of the inner rotating member or the outer rotating member, a screw through hole provided in the pressure member, and a screw member that passes through the screw through hole and screws into the female threaded hole.

4. 2. The overload protection device according to claim 1, wherein the static friction force between the inner peripheral transmission surface and the outer peripheral surface of the inner rotating member is smaller than the static friction force between the outer peripheral transmission surface and the inner peripheral surface of the outer rotating member.

5. 2. The overload protection device according to claim 1, wherein the inner peripheral transmission surface is a surface-treated surface.

6. 6. The overload protection device according to claim 5, wherein the surface treatment of the inner peripheral transmission surface is a coating treatment using a high-hardness material.

7. 7. The overload protection device according to claim 6, wherein the inner peripheral transmission surface has a surface hardness of HV 1500 or more.

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