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 Art

[0002] An example of a torque limiter is shown in Patent Document 1 below. The torque limiter shown in Patent Document 1 below includes 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 composed of a coil spring that is non-rotatably locked to the outer member and applies a braking torque in close contact with the outer peripheral surface of the inner member. 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 are each provided with one annular support wall that extends in the radial direction and supports the inner member from both axial sides. When a rotational torque around the central axis that relatively rotates the inner member and the outer member is applied, when the rotational torque is greater than a predetermined value, the inner member and the outer member rotate relative to each other by overcoming the braking torque.

[0003] A torque limiter is generally used as a component that disconnects the load to protect the motor when an overload is applied to a driving source such as a motor, that is, a component that limits the transmitted torque. Further, the torque limiter is also used as an angular position holding device when, for example, a hatchback of a vehicle is rotationally driven by a driving means such as an electric motor, and can fix the hatchback at an arbitrary angle without using an electromagnetic brake, and at the same time, can swing the hatchback up and down by adding an extra torque with the electric motor. In any usage form, since the torque limiter is a mechanical component that transmits / shuts off the rotational power of an external device, the torque limiter is arranged adjacent to the external device in the axial direction (that is, in series).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] As described above, a torque limiter is a mechanical component that transmits / blocks the rotational power of external equipment, and therefore, lubricants such as grease or oil are applied to the inside of the torque limiter and the external equipment. Such lubricants may leak out due to vibrations and shocks during operation, and since the torque limiter is positioned adjacent to the external equipment in the axial direction, the lubricant leaked from the external equipment will try to enter the inside of the torque limiter from its axial end. In the torque limiter shown in Patent Document 1, both the support wall on the main body side and the support wall on the shield side are annular, and the lubricant leaked from the external equipment can easily enter the inside of the torque limiter if it passes through the inner circumferential surface of the support walls of the main body and shield. When the lubricant leaked from the external equipment enters the inside of the torque limiter and mixes with the lubricant originally applied to the inside of the torque limiter, the properties of the lubricant originally applied to the inside of the torque limiter may become abnormal, and the torque limiter may not be able to perform as intended.

[0006] The present invention has been made in view of the above facts, and its main technical objective is to provide a novel and improved torque limiter that can prevent as much as possible the intrusion of lubricant leaking from external equipment into the inside of the outer member. [Means for solving the problem]

[0007] As a result of diligent study, the inventors have formed a circular recess or an annular groove extending continuously in the circumferential direction in the center of both axial end faces of the inner member, and each of the pair of support walls has a cylindrical shape that enters the recess or groove. blocking wall We found that the above-mentioned main technical challenges could be solved by forming [this structure].

[0008] In other words, according to the present invention, as a torque limiter that solves the above main technical problems, the present invention 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 the outer circumferential surface of the inner member and / or the inner circumferential surface of the outer member and applies braking torque, The outer member is composed of a cylindrical body and a shield that closes the open end of the body, and the outer member has a pair of annular support walls that extend radially and support the inner member from both axial sides. In a torque limiter in which, when a rotational torque is applied around the central axis causing the inner member and the outer member to rotate relative to each other, the rotational torque is greater than a predetermined value, and the inner member and the outer member rotate relative to each other, overcoming the braking torque, 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 each of the pair of support walls enters the recess or groove. This prevents lubricant leaking from connected external devices from entering the inside of the outer member. cylindrical shape blocking wall A torque limiter is provided, characterized in that it has a certain feature formed thereon.

[0009] Preferably, the above blocking wall The outer circumferential surface of the inner member supports the inner circumferential surface of the recess or groove in the inner member in the radial direction, and blocking wall The axial end face of the support wall axially supports the bottom surface of the recess or groove in the inner member. Preferably, each of the pair of support walls has an annular support groove into which the axial end of the inner member is fitted. . good 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 surface of the inner member. The outer member is fixed and the inner member is connected to an external device, and it can be used as an angular position holding device. [Effects of the Invention]

[0010] In the torque limiter configured according to the present invention, 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 each of the pair of support walls has a cylindrical shape that enters the recess or groove. blocking wall Because of the formation, in order for lubricant leaking from external equipment to penetrate the inside of the outer member, the above blocking wall We need to overcome this. In other words, blocking wall Because it functions as a kind of weir, the torque limiter configured according to the present invention prevents as much as possible the lubricant leaking from the connected external device from entering the inside of the outer member. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing the configuration of a preferred embodiment of a torque limiter configured according to the present invention. [Figure 2] Figure 1 shows an exploded perspective view of the torque limiter. [Figure 3] Figure 1 shows a separate internal component of the torque limiter. [Figure 4] Figure 1 shows the main body and shield, which constitute the outer components of the torque limiter, as shown individually. [Figure 5] A diagram showing the configuration of a first modified example of a torque limiter configured according to the present invention. [Figure 6] Figure 5 is a perspective view showing the inner component of the torque limiter. [Figure 7] A diagram showing the configuration of a second modified example of a torque limiter configured according to the present invention. [Modes for carrying out the invention]

[0012] The following description will be made in more detail with reference to the accompanying drawings showing preferred embodiments of the torque limiter configured according to the present invention. In the following description, unless otherwise specified, "one side" and "the other side" in the axial direction refer to the left side and the right side, respectively, based on the state shown in the cross-section AA of Figure 1.

[0013] Referring to FIGS. 1 and 2, the torque limiter indicated as a whole by reference numeral 2 includes an inner member 4, an outer member 6, and a braking member 8. The inner member 4 and the outer member 6 have a common central axis o. As can be easily understood, in the cross-sectional view taken along the line A-A in FIG. 1, the braking member 8 is shown with light ink applied thereto (the same applies to FIGS. 5 and 7 described later).

[0014] The inner member 4 will be described with reference to FIG. 3 in both FIGS. 1 and 2. In the illustrated embodiment, the inner member 4 is a cylindrical shape integrally formed by powder metallurgy, and the cross-section of the outer peripheral surface of the inner member 4 is circular. Circular recesses 10 are formed at the centers of both end faces in the axial direction of the inner member 4. The diameters and depths of the two recesses 10 are equal. The inner diameter of the intermediate portion 14 defined between the end portions 12 on both sides in the axial direction 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 peripheral surface of the intermediate portion 14.

[0015] Next, the outer member 6 will be described with reference to FIGS. 4 together with FIGS. 1 and 2. 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, and both of them are formed of an appropriate synthetic resin. Mainly referring to FIG. 4(a), the main body 20 includes a cylindrical outer peripheral wall 24 that linearly extends in the axial direction and an annular one-sided support wall 26 that extends radially inward from the inner peripheral surface of the outer peripheral wall 24 at an intermediate portion in the axial direction of the outer peripheral wall 24. A one-sided holding portion 28 having a required shape is formed on the inner peripheral surface of one axial end portion of the outer peripheral wall 24. Four arc-shaped cutouts 30 that are locally displaced axially to one side are formed at equal angular intervals in the circumferential direction at the other axial end of the outer peripheral wall 24. At the circumferential center of the bottom surfaces (i.e., the surfaces facing the other axial side) of the four cutouts 30, a pair of slits 32a and 32b that linearly extend axially to one side and penetrate radially are respectively formed. A locking protrusion 34 that protrudes radially inward is formed at the other axial end of the inner peripheral surface of the outer peripheral wall 24 between the pair of slits 32a and 32b. On the inner peripheral surface of the outer peripheral wall 24, a pair of auxiliary walls 36a and 36b that extend from the other axial surface of the one-sided support wall 26 to the one axial end of each of the pair of slits 32a and 32b are provided. Each of the pair of auxiliary walls 36a and 36b has an arc shape and is arranged at equal angular intervals in the circumferential direction, and spaces 38a and 38b are defined between the pair of auxiliary walls 36a and 36b. Each of the pair of auxiliary walls 36a and 36b is provided with a relief portion 40 as appropriate. At the inner peripheral edge of the other axial surface of the one-sided support wall 26, a cylindrical one-sided blocking wall 42 is formed. On the other axial surface of the one-sided support wall 26, a one-sided blocking wall annular one-sided support groove 44 that surrounds the outer peripheral edge of 42 is also formed.

[0016] Mainly referring to FIG. 4(b), the shield 22 includes an annular other-sided support wall 46 that extends radially perpendicular to the axial direction. At the inner peripheral edge of the one axial surface of the other-sided support wall 46, a cylindrical other-sided blocking wall48 is formed. A cylindrical auxiliary wall 50 is also formed on one axial side of the other side support wall 46, and the auxiliary wall 50 and the other side blocking wall A ring-shaped other-side support groove 52 is defined between 48 and the other side support wall 46. A required-shaped other-side holding portion 54 is formed on the other axial side of the other-side support wall 46. On the other axial side of the outer circumferential surface of the other-side support wall 46, four arc-shaped engaging pieces 56 are arranged at equal angular intervals in the circumferential direction, extending axially beyond the other axial end edge of the other-side support wall 46. At the circumferential center of the inner circumferential surface of each of the four engaging pieces 56, a recess 58 is formed that penetrates axially, with the inner diameter locally increased. A recess 60 is formed on the outer circumferential surface of the other-side support wall 46 that faces the recess 58 when viewed in the axial direction. Referring to the AA cross-sectional view in Figure 4(b), the recess 60 extends from the other axial end face to the axial end of the other-side support wall 46, and a locking projection 62 is provided at this axial end.

[0017] The main body 20 and the shield 22 are joined together when the engaging piece 56 of the shield 22 is fitted into the notch 30 of the main body 20, and the locking projection 34 of the main body 20 elastically overcomes and locks onto the locking projection 62 of the shield 22. Prior to the joining of 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 cross-sectional view AA in Figure 1, one side of the main body 20 blocking wall 42 enters the recess 10 formed on one axial end face of the inner member 4, and the other side of the shield 22 blocking wall 48 enters the recess 10 formed on the axial end face of the inner member 4. One side blocking wall 42 and the other side blocking wall Both 48 are cylindrical in shape, and in the illustrated embodiment, one side blocking wall 42 and the other side blocking wall The outer surface of 48 radially supports the inner surface of the recess 10 of the inner member 4, and on one side blocking wall 42 and the other side blocking wallThe axial end face of 48 supports the bottom surface 16 of the recess 10 of the inner member 4 in the axial direction. In the illustrated embodiment, one axial end of the inner member 4 is further fitted into the one-sided support groove 44 of the main body 20, and the other axial end is fitted into the other-sided support groove 52 of the shield 22. Thus, the outer member 6 supports the inner member 4 so that it can rotate around 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 comprises 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 extends linearly radially outward at both axial ends of the wound portion 64. The cross-section of the wire is rectangular. In the free state, that is, when 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 circumferential surface of the inner member 4 with the wound portion 64 elastically expanded in diameter, and the inner circumferential surface of the wound portion 64 is in close contact with the outer circumferential 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 cross-sectional views AA and BB of Figure 1, the outer circumferential surface of the winding portion 64 is in close proximity to and facing the inner circumferential surfaces of the auxiliary walls 36a and 36b on the main body 20 of the outer member 6. As shown in the cross-sectional view BB, the pair of hook portions 66a and 66b are both positioned in the space 38a of the main body 20. As a result, when the braking member 8 is rotated relative to the outer member 6 together with the inner member 4, either the pair of hook portions 66a or 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 circumferential surface of the inner member 4, applying the required braking torque by friction. Since the braking member 8 slides against the inner member 4, a fluorine-based lubricant such as grease or oil is applied to the braking member 8.

[0019] Referring to Figure 1, in the illustrated embodiment, the torque limiter 2 is used as an angular position holding device for a hatchback. Therefore, the outer member 6 is fixed to a vehicle (not shown) by a one-sided holding portion 28 provided on the main body 20 and a other-sided holding portion 54 provided on the shield 22, and the inner member 4 is connected to a drive shaft S (dash-dot line) inserted through the 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 together with the drive shaft S relative to the outer member 6, and the hook portion 66a or 66b of the coil spring (braking member 8) attached to the inner member 4 comes into contact with the circumferential end face of the auxiliary wall 36a or 36b of the outer member 6, thereby pushing the spring in a loosening direction. Which of the two hook portions 66a and 66b is pushed depends on the direction of rotation 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 applied by the braking member 8. In the illustrated embodiment, one axial end of the inner member 4 is fitted into a one-sided support groove 44 formed in the main body 20 of the outer member 6, and the other axial end is fitted into a other-sided support groove 52 formed in the shield 22 of the outer member 6. As a result, the inner member 4 can rotate stably relative to the outer member 6. Since 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] In this configuration, external devices such as gearboxes and spindles are connected to both ends of the drive shaft S, and these external devices are positioned adjacent to the torque limiter 2 in the axial direction. Since gearboxes and spindles are mechanical components that transmit rotational power, they are coated with lubricants such as grease or oil. Such lubricants may leak out due to vibrations and shocks during operation, and since the torque limiter 2 is positioned adjacent to the external devices in the axial direction, the lubricants leaking out from the external devices will try to enter the inside of the torque limiter 2, that is, the inside of the outer member 6, from the axial end of the torque limiter 2. In the illustrated embodiment, since the lubricants can move axially along the outer circumferential surface of the drive shaft S, the lubricants will try to enter the inside of the outer member 6 from the inner circumferential surface side of the one-sided support wall 26 and the other-sided support wall 46. However, in the torque limiter configured 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 a cylindrical part is provided on one side of the support wall 26 and the other side of the support wall 46 that enters the recess 10. blocking wall 42 and the other side blocking wall Since 48 is formed, in order for lubricant leaking from the external device to penetrate the inside of the outer member 6, the above one side blocking wall 42 and the other side blocking wall You need to get past 48. That is, one side. blocking wall 42 and the other side blocking wall Since 48 functions as a kind of weir, the torque limiter configured according to the present invention prevents as much as possible the lubricant leaking from the connected external device from entering the inside of the outer member 6. Furthermore, one side blocking wall 42 and the other side blocking wall Both 48 are cylindrical in shape, and in the illustrated embodiment, one side blocking wall 42 and the other side blocking wall The outer surface of 48 radially supports the inner surface of the recess 10 of the inner member 4, and on one side blocking wall 42 and the other side blocking 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 configured according to the present invention. Comparing the torque limiter shown in Figure 5 with the torque limiter shown in Figure 1, the only difference between the two is the configuration of the inner members; the other configurations are substantially identical. Therefore, in the following description, only the above-mentioned differences will be explained, and for identical configurations, the same number will be assigned 100, and detailed explanations will be omitted.

[0022] In the torque limiter 102 shown in Figure 5, the inner member 104 consists of a connecting member 104a made of synthetic resin or soft metal, which is provided with a connecting portion (serration 118) for connecting to an external device, and a metal part that is mounted on the outer surface of the connecting member 104a and is not rotatable relative to the connecting member 104a. Operating member It consists of 104b and 104a. Referring also to Figure 6, the connecting member 104a is integrally molded from a relatively high-strength synthetic resin such as PPS and has an overall cylindrical shape. The recesses 110 are formed on both axial end faces of the connecting member 104a. Multiple engagement protrusions 168, with a circular arc cross-section and extending linearly in the axial direction, are arranged on the outer circumferential surface of the connecting member 104a at equal angular intervals. On the other hand, Operating member 104b is integrally molded by powder metallurgy and has an overall cylindrical shape. Operating member The outer surface of 104b has a circular cross-section, and the braking member 108 is attached to this outer surface. Operating member Multiple engagement grooves 170, each with a circular arc cross-section and extending linearly in the axial direction, are arranged at equal angular intervals in the circumferential direction on the inner surface of 104b, corresponding to multiple engagement protrusions 168 arranged on the outer surface of the connecting member 104a. The engagement protrusions 168 are fitted into the engagement grooves 170, thereby connecting the connecting member 104a and Operating member It is engaged with 104b in a way that prevents relative rotation.

[0023] In this embodiment, the inner member 104 consists of a connecting member 104a made of synthetic resin and a metal Operating member The connecting member 104a, which is composed of 104b and has serrations 118 formed on it that serve as a connecting portion, and the braking member 108 act on it. Operating member104b is molded separately. This is advantageous compared to the case where the inner member is integrally molded by powder metallurgy in the following respects. Since the braking member 108 is in close contact with the outer circumferential surface of the inner member and applies the required braking torque, barrel polishing is performed on the outer circumferential surface of the inner member that is in close contact with the braking member 108 after centerless polishing so that the required braking torque is stably generated. Here, if a connecting part such as serrations is formed when barrel polishing is performed, it is undesirable because the connecting part will be damaged by barrel polishing. However, in this embodiment, barrel polishing should be performed. Operating member Since 104b and the connecting member 104a, which has serrations 118 forming a connection portion, are molded separately, Operating member By applying barrel polishing only to 104b, damage to the serration 118, which is the connecting part, can be avoided. Furthermore, if the connecting member 104a is made of synthetic resin, resin molding can be performed with higher precision than powder metallurgy, allowing the connecting part to be molded with high precision. Even if the connecting member 104a is made of a soft metal such as aluminum or zinc, die casting can be used to mold the connecting part with high precision.

[0024] Figure 7 shows a second modified example of a torque limiter configured according to the present invention. Comparing the torque limiter shown in Figure 7 with the torque limiter shown in Figure 1, the only difference between the two is the configuration of the internal components; the other configurations are substantially identical. Therefore, in the following description, only the above-mentioned differences will be explained, and for identical components, the same number will be assigned 200, and detailed explanations will be omitted.

[0025] In the torque limiter 202 shown in Figure 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 side in the axial direction (therefore the shaft portion 270 extends along the central axis o), and serrations 218, which are connection portions, are formed on the outer circumferential surface of the shaft portion 270. In this embodiment, a circular recess 210a is formed in the center of one end face in the axial direction of the inner member 204, while an annular groove 210b is formed on the other end face in the axial direction, surrounding the outer circumferential edge of the base end of the shaft portion 270. blocking wall Vehicle 248 is entering groove 210b.

[0026] Although a torque limiter configured according to the present invention has been described in detail above with reference to the attached drawings, the present invention is not limited to the embodiments described above, and appropriate modifications and changes are possible without departing from the present invention. For example, in the illustrated embodiment, the braking member 8 is a coil spring and has a pair of hook portions 66a and 66b, but the hook portion may be single. If the coil spring has only a single hook portion, the torque limiter functions as a unidirectional torque limiter. The coil spring may be locked to the inner member so as not to rotate relative to it and 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, but may be a leaf spring, ring spring, tolerance ring, etc. In addition, the body of the outer member may penetrate in the axial direction, and both axial ends of the body may be closed with a pair of shields. In this case, the support walls are provided on each of the pair of shields arranged on both sides in the axial direction. The torque limiter of the present invention is not limited to use as an angular position holding device, but can be applied to various applications. [Explanation of Symbols]

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

Claims

1. The device 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 the outer circumferential surface of the inner member and / or the inner circumferential surface of the outer member and applies braking torque. The outer member is composed of a cylindrical body and a shield that closes the open end of the body, and the outer member has a pair of annular support walls that extend radially and support the inner member from both axial sides. In a torque limiter in which, when a rotational torque is applied around the central axis causing the inner member and the outer member to rotate relative to each other, the rotational torque is greater than a predetermined value, and the inner member and the outer member rotate relative to each other, overcoming the braking torque, A torque limiter characterized in 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 blocking wall is formed on each of the pair of support walls to prevent lubricant flowing out from an external device connected to the recess or groove from entering the inside of the outer member.

2. The torque limiter according to claim 1, wherein the outer circumferential surface of the blocking wall radially supports the inner circumferential surface of the recess or groove in the inner member, and the axial end surface of the blocking wall axially supports the bottom surface of the recess or 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 into which the axial end of the inner member is fitted.

4. 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.

5. The torque limiter according to claim 1, wherein the braking member is a coil spring that 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.

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

Images