Torque limiter

Abstract

To provide a new torque limiter capable of preventing a lubricant flowing out from an external apparatus from entering the inside of an outside member as much as possible.SOLUTION: A circular recessed part 10 or an annular recessed groove side 210b continuously extending in the peripheral direction is formed in the center of axial both side end surfaces of an inside member 4, and cylindrical preventive walls 42 and 48 entering the recessed part 10 or the recessed groove side 210b are formed in a pair of support walls 26 and 46.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a torque limiter. [Background technology]

[0002] An example of a torque limiter is disclosed in Patent Document 1 below. The torque limiter disclosed in Patent Document 1 below includes an inner member, an outer member that houses the inner member and shares a central axis with the inner member, and a braking member that is engaged with the outer member so as not to rotate relative to the inner member and is made of a coil spring that is in close contact with the outer peripheral surface of the inner member and applies a braking torque. The outer member is composed of a cylindrical main body and a shield that closes the open end of the main body. The main body and the shield each have an annular support wall that extends radially and supports the inner member from both axial sides. When a rotational torque about the central axis that rotates the inner member and the outer member relative to each other is applied, the braking torque is overcome and the inner member and the outer member rotate relative to each other if the rotational torque is greater than a predetermined value.

[0003] Torque limiters are generally used as components that protect a drive source, such as a motor, by disconnecting the load when the motor is overloaded, i.e., as a component that limits the transmitted torque. Furthermore, torque limiters are also used as devices for maintaining the angular position of a vehicle hatchback when the vehicle is rotated by a driving means such as an electric motor, and can fix the hatchback at a desired angle without using an electromagnetic brake, while simultaneously applying excess torque from the electric motor to allow the hatchback to swing open and close up and down. In either case, the torque limiter is a mechanical component that transmits / disconnects the rotational power of an external device, and is therefore arranged adjacent to the external device in the axial direction (i.e., in series). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-110739 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, torque limiters are mechanical components that transmit and interrupt the rotational power of external equipment. Therefore, lubricants such as grease and oil are applied to the interior of the torque limiter and the external equipment. Such lubricants can leak out due to vibrations and shocks during operation. Because the torque limiter is positioned axially adjacent to the external equipment, lubricants leaking from the external equipment tend to infiltrate the inside of the torque limiter from the axial end of the torque limiter. In the torque limiter disclosed in Patent Document 1, the support wall on the main body side and the support wall on the shield side are both annular. Therefore, lubricants leaking from the external equipment can easily infiltrate the inside of the torque limiter by simply passing through the inner circumferential surfaces of the support walls of the main body and the shield. If lubricants leaking from the external equipment infiltrate the inside of the torque limiter and mix with the lubricants originally applied to the inside of the torque limiter, the lubricants originally applied to the inside of the torque limiter may become abnormal, potentially preventing the torque limiter from performing its intended function.

[0006] The present invention has been made in consideration of the above facts, and its main technical object is to provide a new and improved torque limiter that can prevent as much as possible lubricant that has leaked from an external device from entering the inside of the outer member. [Means for solving the problem]

[0007] As a result of intensive research, the inventors have found that a circular recess or an annular groove extending continuously in the circumferential direction is formed in the center of both axial end faces of the inner member, and a cylindrical recess or an annular groove is formed in each of the pair of support walls so as to enter the recess or groove. Entry wall It has been found that the above-mentioned main technical problems can be solved by forming the above-mentioned

[0008] That is, according to the present invention, a torque limiter that solves the above-mentioned main technical problem comprises an inner member, an outer member that houses the inner member and has a common central axis with the inner member, and a braking member that is in close contact with an outer peripheral surface of the inner member and / or an inner peripheral surface of the outer member and applies a braking torque, the outer member is composed of a cylindrical main body and a shield that closes an open end of the main body, and the outer member has a pair of annular support walls that extend radially and support the inner member from both axial sides, a torque limiter configured such that, when a rotational torque about the central axis is applied to rotate the inner member and the outer member relative to each other, the rotational torque overcomes the braking torque and the inner member and the outer member rotate relatively if the rotational torque is greater than a predetermined value, A circular recess or a circular ring-shaped recessed groove extending continuously in the circumferential direction is formed in the center of each of the axial end faces of the inner member, and each of the pair of support walls has a cylindrical recess that enters the recess or the recessed groove. Entry wall is formed.

[0009] Preferably, the Entry wall The outer peripheral surface of the inner member supports the inner peripheral surface of the recess or the recessed groove in the radial direction, and Entry wall The axial end surfaces of the support walls support the bottom surfaces of the recesses or grooves in the inner member in the axial direction. Each of the pair of support walls preferably has an annular support groove formed therein into which the axial end portions of the inner member are fitted. The inner member comprises a connecting member made of synthetic resin or soft metal provided with a connecting portion for connecting to an external device, and a metal connecting member attached to the outer peripheral surface of the connecting member and unable to rotate relative to the connecting member. Mounted member Preferably, one of the pair of support walls is disposed on the main body and the other on the shield. The braking member is preferably a coil spring, which is locked to the outer member so as not to rotate relative to it and is in close contact with the outer circumferential surface of the inner member. The outer member is fixed and the inner member is connected to an external device, and the device can be used as an angular position maintaining device. [Effects of the Invention]

[0010] In the torque limiter constructed according to the present invention, a circular recess or a ring-shaped recessed groove extending continuously in the circumferential direction is formed in the center of both axial end faces of the inner member, and each of the pair of support walls has a cylindrical recess that enters the recess or recessed groove. Entry wall By forming the above, the lubricant flowing out from the external device cannot penetrate into the inside of the outer member. Entry wall It is necessary to overcome this. Entry wall functions as a dam, so that the torque limiter constructed according to the present invention prevents as much as possible the lubricant that has flowed out from the connected external device from entering the inside of the outer member. [Brief explanation of the drawings]

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0012] A torque limiter constructed according to the present invention will be described in further detail below with reference to the accompanying drawings showing preferred embodiments thereof. In the following description, unless otherwise specified, "one side" and "the other side" in the axial direction refer to the left side and "the other side" in the state shown in the AA cross section of Figure 1 as the reference.

[0013] 1 and 2, the torque limiter generally designated by the numeral 2 comprises an inner member 4, an outer member 6, and a braking member 8. The inner member 4 and the outer member 6 share a common central axis o. For ease of understanding, the braking member 8 is indicated by light ink in the cross-sectional view taken along line AA in FIG. 1 (the same applies to FIGS. 5 and 7, which will be described later).

[0014] The inner member 4 will be described with reference to Figures 1 and 2 as well as Figure 3. In the illustrated embodiment, the inner member 4 has a cylindrical shape that is integrally molded by powder metallurgy, and the cross section of the outer circumferential surface of the inner member 4 is circular. Circular recesses 10 are formed in the centers of both axial end faces of the inner member 4. The two recesses 10 have the same diameter and depth. The inner diameter of an intermediate portion 14 defined between both axial end portions 12 where the recesses 10 are formed is slightly smaller than the inner diameter of the end portions 12, and an annular bottom surface 16 perpendicular to the axial direction is defined at the bottom of the recess 10. Serrations 18 are formed on the inner circumferential surface of the intermediate portion 14.

[0015] Next, the outer member 6 will be described with reference to Figures 1, 2, and 4. The outer member 6 is composed of a cylindrical main body 20 and a shield 22 that closes the open end of the main body 20. In the illustrated embodiment, the outer member 6 includes one main body 20 and one shield 22, both of which are molded from an appropriate synthetic resin. Mainly referring to Figure 4(a), the main body 20 includes a cylindrical outer wall 24 that extends linearly in the axial direction and a ring-shaped one-side support wall 26 that extends radially inward from the inner circumferential surface of the outer wall 24 at an axially intermediate portion of the outer wall 24. A one-side retaining portion 28 of a required shape is formed on the inner circumferential surface of one axial end of the outer wall 24. Four arc-shaped notches 30 that are locally displaced axially to one side are formed at equiangular intervals in the circumferential direction on the other axial end of the outer wall 24. A pair of slits 32a and 32b extending linearly toward one axial side and penetrating radially are formed in the circumferential center of each of the bottom surfaces (i.e., the surfaces facing the other axial side) of the four notches 30. A locking projection 34 protruding radially inward is formed at the other axial end of the inner circumferential surface of the outer peripheral wall 24 between the pair of slits 32a and 32b. The inner circumferential surface of the outer peripheral wall 24 is further provided with a pair of auxiliary walls 36a and 36b extending from the other axial side of the one-side support wall 26 to each axial end of the pair of slits 32a and 32b. Each of the pair of auxiliary walls 36a and 36b has an arc shape and is disposed at equal angular intervals in the circumferential direction, defining spaces 38a and 38b between the pair of auxiliary walls 36a and 36b. A lightening portion 40 is appropriately provided in each of the pair of auxiliary walls 36a and 36b. The inner peripheral edge of the other axial side of the one-side support wall 26 is provided with a cylindrical one-side Entry wall On the other side of the one-side support wall 26 in the axial direction, a one-side Entry wall A circular one-sided support groove 44 is also formed around the outer periphery of the support 42.

[0016] 4(b), the shield 22 is provided with a circular ring-shaped other-side support wall 46 extending perpendicular to the axial direction and therefore in the radial direction. Entry wallA cylindrical auxiliary wall 50 is also formed on one axial side of the other-side support wall 46. Entry wall A circular other-side support groove 52 is defined between the other support wall 46 and the other axial side surface of the other support wall 46. A required shape other-side retaining portion 54 is formed on the other axial side of the outer peripheral surface of the other support wall 46. Four arc-shaped engagement pieces 56 are arranged at equal angular intervals in the circumferential direction on the other axial side of the outer peripheral surface of the other support wall 46, extending beyond the other axial end edge of the other support wall 46 to the other axial side. The inner diameter of each of the four engagement pieces 56 is locally increased at the circumferential center of the inner peripheral surface to form a recess 58 penetrating in the axial direction. A recess 60 is formed in the outer peripheral surface of the other support wall 46 facing the recess 58 when viewed in the axial direction. Referring to the AA cross-sectional view of FIG. 4(b), the recess 60 extends from the other axial end surface of the other support wall 46 to one axial end, and a locking projection 62 is provided at this one axial end.

[0017] The main body 20 and the shield 22 are combined by fitting the engagement piece 56 of the shield 22 into the notch 30 of the main body 20, and the locking protrusion 34 of the main body 20 elastically climbing over the locked protrusion 62 of the shield 22 and being locked thereto. Prior to combining the main body 20 and the shield 22, the inner member 4 is housed inside the outer member 6. At this time, as can be understood by referring to the AA cross section of FIG. 1, one side of the main body 20 is Entry wall 42 enters the recess 10 formed on one axial end surface of the inner member 4 and Entry wall 48 enters the recess 10 formed on the other axial end surface of the inner member 4. Entry wall 42 and other sides Entry wall 48 are both cylindrical, and in the illustrated embodiment, Entry wall 42 and other sides Entry wall The outer peripheral surface of the inner member 4 supports the inner peripheral surface of the recess 10 of the inner member 4 in the radial direction, and Entry wall 42 and other sides Entry wallThe axial end surface of the inner member 4 is fitted into the one-side support groove 44 of the main body 20, and the other axial end is fitted into the other-side support groove 52 of the shield 22. Thus, the outer member 6 supports the inner member 4 so as to be rotatable about the central axis o.

[0018] The braking member 8 will be described with reference to Figures 1 and 2. In the illustrated embodiment, the braking member 8 is a coil spring made of a metal wire, and includes a wound portion 64 in which the wire is wound in a spiral shape, and a pair of hook portions 66a and 66b in which the wire is linearly extended radially outward at both axial ends of the wound portion 64. The cross section of the wire is rectangular. In a free state, that is, in a state in which no external force is applied to the pair of hook portions 66a and 66b, the inner diameter of the wound portion 64 is smaller than the outer diameter of the inner member 4, and the braking member 8 is attached to the outer peripheral surface of the inner member 4 with the wound portion 64 elastically expanded in diameter, and the inner peripheral surface of the wound portion 64 is in close contact with the outer peripheral surface of the inner member 4. The braking member 8 is housed inside the outer member 6 together with the inner member 4. As shown in the AA and BB cross-sectional views of FIG. 1 , the outer peripheral surface of the wound portion 64 closely faces the inner peripheral surfaces of the auxiliary walls 36a and 36b of the main body 20 of the outer member 6. As shown in the BB cross-sectional view, the pair of hook portions 66a and 66b are both disposed in the space 38a of the main body 20. As a result, when the braking member 8 is rotated together with the inner member 4 relative to the outer member 6, one of the pair of hook portions 66a and 66b abuts against the circumferential end surface of the auxiliary wall 36a or 36b in the space 38a of the outer member 6. Thus, the braking member 8 is locked to the outer member 6 so as not to rotate relative to it, and is in close contact with the outer peripheral surface of the inner member 4, applying the required braking torque by frictional force. Because the braking member 8 slides relative to the inner member 4, a fluorine-based lubricant such as grease or oil is applied to the braking member 8.

[0019] Explaining with reference to FIG. 1, in the illustrated embodiment, the torque limiter 2 is used as an angular position maintaining device for a hatchback. To this end, the outer member 6 is fixed to a vehicle (not shown) by a one-side retaining portion 28 provided on the main body 20 and a other-side retaining portion 54 provided on the shield 22, and the inner member 4 is connected to a drive shaft S (shown by a two-dot chain line) inserted inside by serrations 18. When the drive shaft S is rotated by a drive source such as an electric motor, the inner member 4 rotates integrally with the drive shaft S relative to the outer member 6, causing the hook portion 66a or 66b of the coil spring (brake member 8) attached to the inner member 4 to abut against the circumferential end surface of the auxiliary wall 36a or 36b of the outer member 6, thereby pushing the spring in a direction that loosens it. Which of the two hook portions 66a or 66b is pushed depends on the rotational direction of the drive shaft S. When the rotational torque applied to the drive shaft S is greater than a predetermined value, the inner member 4 and the outer member 6 rotate relative to each other, overcoming the required braking torque from the braking member 8. In the illustrated embodiment, one axial end of the inner member 4 is fitted into the one-side support groove 44 formed in the main body 20 of the outer member 6, and the other axial end is fitted into the other-side support groove 52 formed in the shield 22 of the outer member 6, so that the inner member 4 can rotate stably with respect to the outer member 6. Because the drive shaft S can rotate in both forward and reverse directions, the torque limiter 2 in the illustrated embodiment functions as a so-called bidirectional torque limiter.

[0020] Here, external devices such as a gearbox and a spindle are connected to both ends of the drive shaft S, and these external devices are arranged axially adjacent to the torque limiter 2. Because the gearbox, spindle, etc. are mechanical components that transmit rotational power, lubricants such as grease and oil are applied to their interiors. Such lubricants may leak out due to vibrations, shocks, etc. during operation. Since the torque limiter 2 is arranged axially adjacent to the external devices, the lubricant leaked from the external devices tends to infiltrate into the inside of the torque limiter 2, i.e., the inside of the outer member 6, from the axial end of the torque limiter 2. In the illustrated embodiment, the lubricant can move axially along the outer peripheral surface of the drive shaft S, and therefore tends to infiltrate into the inside of the outer member 6 from the inner peripheral surfaces of the one-side support wall 26 and the other-side support wall 46. However, in the torque limiter constructed according to the present invention, a circular recess 10 is formed in the center of both axial end faces of the inner member 4, and one side support wall 26 and the other side support wall 46 each have a cylindrical one side recess 10 that enters the recess 10. Entry wall 42 and other sides Entry wall Since the lubricant flowing out from the external device has to penetrate into the inside of the outer member 6 through the above-mentioned one side. Entry wall 42 and other sides Entry wall You need to get over 48. That is, one side Entry wall 42 and other sides Entry wall Since the lubricant 48 functions as a weir, the torque limiter constructed according to the present invention prevents as much as possible the lubricant flowing out from the connected external device from entering the inside of the outer member 6. Entry wall 42 and other sides Entry wall 48 are both cylindrical, and in the illustrated embodiment, Entry wall 42 and other sides Entry wall The outer peripheral surface of the inner member 4 supports the inner peripheral surface of the recess 10 of the inner member 4 in the radial direction, and Entry wall 42 and other sides Entry wall Since the axial end face of 48 supports the bottom surface 16 of the recess 10 of the inner member 4 in the axial direction, runout between the inner member 4 and the outer member 6 is also prevented.

[0021] Figure 5 shows a first modified example of a torque limiter constructed in accordance with the present invention. Comparing the torque limiter shown in Figure 5 with the torque limiter shown in Figure 1, the only difference is the configuration of the inner member, and the other configurations are substantially the same. Therefore, in the following explanation, only the above differences will be explained, and the same configurations will be designated by the same reference numerals with the number 100 and will not be explained in detail.

[0022] In the torque limiter 102 shown in FIG. 5, the inner member 104 is made of a connecting member 104a made of synthetic resin or soft metal and provided with a connecting portion (serrations 118) for connecting to an external device, and a metal connecting member 104b attached to the outer circumferential surface of the connecting member 104a and unable to rotate relative to the connecting member 104a. Mounted member 6, the connecting member 104a is integrally molded from a synthetic resin having a relatively high strength such as PPS, and has an overall cylindrical shape. The recesses 110 are formed on both axial end surfaces of the connecting member 104a. On the outer peripheral surface of the connecting member 104a, a plurality of engaging ridges 168 having an arc-shaped cross section and extending linearly in the axial direction are arranged at equal angular intervals in the circumferential direction. Mounted member The member 104b is integrally formed by powder metallurgy and has an overall cylindrical shape. Mounted member The cross section of the outer peripheral surface of 104b is circular, and a braking member 108 is attached to this outer peripheral surface. Mounted member On the inner peripheral surface of the connecting member 104b, a plurality of engaging grooves 170, each having an arc-shaped cross section and extending linearly in the axial direction, are arranged at equal angular intervals in the circumferential direction in correspondence with the plurality of engaging ridges 168 arranged on the outer peripheral surface of the connecting member 104a. Mounted member 104b are engaged with each other so as not to rotate relative to each other.

[0023] In this embodiment, the inner member 104 is made of a synthetic resin connecting member 104a and a metal connecting member 104b. Mounted member The connecting member 104a is formed with serrations 118, which are the connecting portions, and the braking member 108 acts on the connecting member 104a. Mounted member104b. This is more advantageous than when the inner member is integrally molded by powder metallurgy in the following respects. The braking member 108 is in close contact with the outer peripheral surface of the inner member to apply the required braking torque, so that the outer peripheral surface of the inner member that is in close contact with the braking member 108 is subjected to barrel polishing after centerless polishing so that the required braking torque is stably generated. Here, if a connecting portion such as a serration is formed when barrel polishing is performed, the connecting portion will be damaged by the barrel polishing, which is not preferable. However, in this embodiment, the outer peripheral surface of the inner member that is to be subjected to barrel polishing is Mounted member 104b and the connecting member 104a on which the serrations 118 are formed, which are the connecting portions, are molded separately. Mounted member By performing barrel polishing only on 104b, it is possible to avoid damage to the serrations 118, which are the connecting portion. Furthermore, when the connecting member 104a is made of synthetic resin, the connecting portion can be formed with high precision because resin molding allows for higher precision molding than powder metallurgy. Even when the connecting member 104a is made of a soft metal such as aluminum or zinc, the connecting portion can be formed with high precision by die casting.

[0024] Figure 7 shows a second modified example of a torque limiter constructed in accordance with the present invention. Comparing the torque limiter shown in Figure 7 with the torque limiter shown in Figure 1, the only difference is the configuration of the inner member, and the other configurations are substantially the same. Therefore, in the following explanation, only the above differences will be explained, and the same configurations will be designated by the same reference numerals with the number 200 and will not be explained in detail.

[0025] In the torque limiter 202 shown in Fig. 7, the inner member 204 is integrally molded by powder metallurgy. The inner member 204 has a shaft portion 270 that penetrates the center of the shield 222 and extends to the other axial side (therefore, the shaft portion 270 extends along the central axis o), and serrations 218, which serve as connecting portions, are formed on the outer peripheral surface of the shaft portion 270. In this embodiment, a circular recess 210a is formed in the center of one axial end face of the inner member 204, and an annular recessed groove 210b is formed on the other axial end face that surrounds the outer peripheral edge of the base end of the shaft portion 270. Entry wall 248 extends into the recessed groove 210b.

[0026] Although the torque limiter constructed according to the present invention has been described above in detail with reference to the accompanying drawings, the present invention is not limited to the above-described embodiment, and appropriate modifications and variations are possible within the scope of the present invention. For example, in the illustrated embodiment, the braking member 8 is a coil spring having a pair of hook portions 66a and 66b. However, the braking member 8 may have only a single hook portion. If the coil spring has only a single hook portion, the torque limiter functions as a one-way torque limiter. The coil spring may be locked to the inner member so as not to rotate relative to the inner member and be in close contact with the inner circumferential surface of the outer member. Furthermore, the braking member does not necessarily have to be a coil spring; it may be a leaf spring, annular spring, tolerance ring, or the like. Furthermore, the main body of the outer member may penetrate axially, and both axial ends of the main body may be closed by a pair of shields. In this case, a support wall is provided on each of the pair of shields located on both axial sides. The torque limiter of the present invention is not limited to use as an angular position maintaining device and can be used for various purposes. [Explanation of symbols]

[0027] 2: Torque limiter 4: Inner member 6:Outer member 8: Braking member 10: Recess 20: (outer member) main body 22: Shield (of outer member) 26: One-sided support wall 42:One side Entry wall 46:Other side support wall 48: Other side Entry wall

Claims

1. the brake system comprises an inner member, an outer member that houses the inner member and has a common central axis with the inner member, and a braking member that is in close contact with an outer peripheral surface of the inner member and / or an inner peripheral surface of the outer member and applies a braking torque, the outer member is composed of a cylindrical main body and a shield that closes an open end of the main body, and the outer member has a pair of annular support walls that extend radially and support the inner member from both axial sides, a torque limiter configured such that, when a rotational torque about the central axis is applied to rotate the inner member and the outer member relative to each other, the rotational torque overcomes the braking torque and the inner member and the outer member rotate relatively if the rotational torque is greater than a predetermined value, a circular recess or a ring-shaped groove extending continuously in the circumferential direction is formed in the center of both axial end faces of the inner member, and a cylindrical blocking wall that enters the recess or groove is formed in each of the pair of support walls.

2. 2. The torque limiter according to claim 1, wherein an outer peripheral surface of the blocking wall radially supports an inner peripheral surface of the recess or the groove in the inner member, and an axial end surface of the blocking wall axially supports a bottom surface of the recess or the groove in the inner member.

3. The torque limiter according to claim 1 , wherein each of the pair of support walls has an annular support groove formed therein, into which an axial end of the inner member is fitted.

4. 2. The torque limiter according to claim 1, wherein the inner member is composed of a connecting member made of synthetic resin or soft metal and provided with a connecting portion for connecting to an external device, and a metal acting member attached to the outer peripheral surface of the connecting member and unable to rotate relative to the connecting member.

5. 2. The torque limiter according to claim 1, wherein one of the pair of support walls is disposed on the main body and the other is disposed on the shield.

6. 2. The torque limiter according to claim 1, wherein said braking member is a coil spring that is locked to said outer member so as not to rotate relative to said outer member and that is in close contact with the outer peripheral surface of said inner member.

7. 2. The torque limiter according to claim 1, wherein the outer member is fixed and the inner member is connected to an external device, and the torque limiter is used as an angular position maintaining device.

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