Torque limiter

Abstract

To provide a novel torque limiter that prevents uneven wear on the outer peripheral surface 10 of an inner member 4 or the inner peripheral surface of an outer member 6 that is in close contact with the inner or outer surface of an action piece 44 of a braking torque applying means 8. The inclination angle of a plurality of action pieces (44) relative to the axial direction and / or the extension length from the base (42) are changed.

Description

[Technical Field]

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

[0002]

[0003] Conventionally, there has been a torque limiter, as shown in Patent Document 1, which includes an inner member that is rotatable relative to the outer member about a common central axis, an outer member that houses at least a portion of the inner member, and a braking torque applying means that is engaged with the outer member and is unrotatable relative to the outer member and applies a required braking torque to the relative rotation, wherein the braking torque applying means has an annular base whose inner peripheral surface faces the cylindrical outer peripheral surface of the inner member, and the inner peripheral edge of the base is provided with a plurality of acting pieces that are spaced apart in the circumferential direction and extend radially inward at an inclination toward one axial direction, with the inner surface of the extending end being in close contact with the outer peripheral surface of the inner member. Such a torque limiter may also be called a torque hinge, an angular position maintaining device, or the like, depending on the manner of use, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3912724 Summary of the Invention [Problem to be solved by the invention]

[0004] In the torque limiter disclosed in Patent Document 1, the braking torque applying means has a plurality of action pieces all of which have the same shape, and therefore the inner surfaces of the plurality of action pieces are all in close contact with the outer peripheral surface of the inner member at the same axial position. As a result, the axial position of the cylindrical outer peripheral surface of the inner member where the inner surfaces of the action pieces are in close contact is subject to localized uneven wear, shortening the service life of the product.

[0005] The present invention has been made in view of the above facts, and its main technical object is to provide a new and improved torque limiter that prevents uneven wear on the outer peripheral surface of the inner member or the inner peripheral surface of the outer member that is brought into close contact with the inner or outer surface of the action piece of the braking torque applying means. [Means for solving the problem]

[0006] As a result of extensive research, the inventors have found that the above-mentioned main technical problem can be solved by changing the inclination angle of the multiple action pieces relative to the axial direction and / or the extension length from the base portion.

[0007] That is, according to a first aspect of the present invention, a torque limiter that solves the above-mentioned main technical problem comprises an inner member that is rotatable relative to the outer member about a common central axis, an outer member that houses at least a part of the inner member, and braking torque applying means that is engaged with the outer member, is unrotatable relative to the outer member, and applies a required braking torque to the relative rotation, In a torque limiter, the braking torque applying means comprises an annular base portion whose inner peripheral surface faces the cylindrical outer peripheral surface of the inner member, and the inner peripheral edge of the base portion is provided with a plurality of action pieces spaced apart in the circumferential direction, the action pieces extending radially inward at an inclination in one axial direction, and the inner surface of the extending end portion being in close contact with the outer peripheral surface of the inner member, There is provided a torque limiter characterized in that the plurality of action pieces have different inclination angles with respect to the axial direction and / or different extension lengths from the base portion.

[0008] Preferably, the braking torque applying means is in the shape of a thin ring. A lubricant is preferably applied between the braking torque applying means and the inner member. Preferably, the inclination angles of the plurality of action pieces relative to the axial direction and / or the extension lengths from the base are different from one another.

[0009] According to a second aspect of the present invention, there is provided an apparatus for applying a braking torque to a bearing, comprising: an inner member rotatable relative to the inner member about a common central axis; an outer member accommodating at least a portion of the inner member; and braking torque applying means engaged with the inner member, non-rotatable relative to the inner member, and applying a required braking torque to the relative rotation, In a torque limiter, the braking torque applying means has an annular base portion whose outer peripheral surface faces the cylindrical inner peripheral surface of the outer member, and the outer peripheral edge of the base portion is provided with a plurality of action pieces spaced apart in the circumferential direction, the action pieces extending radially outward at an inclination in one axial direction, the outer surfaces of the extending ends of which are in close contact with the inner peripheral surface of the outer member, There is provided a torque limiter characterized in that the plurality of action pieces have different inclination angles with respect to the axial direction and / or different extension lengths from the base portion. [Effects of the Invention]

[0010] According to the torque limiter of the present invention, since the inclination angles of the multiple acting pieces relative to the axial direction and / or the extension lengths from the base are different, the inner or outer surfaces of the multiple acting pieces are brought into close contact with the outer peripheral surface of the inner member or the inner peripheral surface of the outer member at different axial positions, respectively. This prevents uneven wear on the outer peripheral surface of the inner member or the inner peripheral surface of the outer member, and extends the service life of the product. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing the overall configuration of a preferred embodiment of a torque limiter constructed according to the present invention; [Figure 2] 2 is a view showing an inner member of the torque limiter shown in FIG. 1 alone. FIG. [Figure 3] 2 is a view showing an outer member of the torque limiter shown in FIG. 1 alone. FIG. [Figure 4] 2 is a view showing a braking torque application means in the torque limiter shown in FIG. 1 alone. FIG. [Figure 5-1] 2 is a left side view of the torque limiter shown in FIG. 1 with a shield member removed. [Figure 5-2] 5-1. FIG. 5-2 is a cross-sectional view taken along each cutting line shown in FIG. [Figure 6] 2 is a diagram showing a schematic view of the inner circumferential surface of the laminated braking torque application means in the torque limiter shown in FIG. 1 in a developed state. DETAILED DESCRIPTION OF THE INVENTION

[0012] A torque limiter constructed according to a preferred embodiment of the present invention will be described in further detail below with reference to the accompanying drawings. In the following description, "one side" and "the other side" in the axial direction refer to the left side and the right side in the AA cross-sectional view of Figure 1, unless otherwise specified.

[0013] Referring to FIG. 1, the torque limiter generally designated by the numeral 2 comprises an inner member 4, an outer member 6, and braking torque applying means 8.

[0014] 1 and 2, the inner member 4 is a cylindrical metallic member that penetrates in the axial direction and has a cylindrical outer peripheral surface 10. A pair of approximately rectangular recesses 12 are formed on both diametrical sides of the inner peripheral edge of one axial side of the inner member 4, and the inner member 4 is connected via these pair of recesses 12 to either a driving side or a driven side external device (not shown) in a state where it cannot rotate relative to the device.

[0015] Referring to FIG. 1 and FIG. 3, the outer member 6 is formed by combining a main body 14 (shown in FIG. 3(a)) and a shield body 16 (shown in FIG. 3(b)). Both the main body 14 and the shield body 16 can be molded from an appropriate synthetic resin. Referring primarily to FIG. 3(a), the main body 14 includes an annular end plate 18 arranged perpendicular to the axial direction and a cylindrical outer wall 20 extending axially from the outer periphery of the end plate 18. The other axial side of the end plate 18 is provided with a cylindrical connecting portion 24 that surrounds the inner periphery and extends axially to the other axial side. The outer periphery of the connecting portion 24 is formed with a pair of flat surfaces 26 that are parallel to each other when viewed axially. The outer member 6 is connected to either a driving or driven external device (not shown) via these flat surfaces 26 in a manner that prevents relative rotation. A recess 28 is formed on one axial side of the end plate 18. The recess 28 has an annular portion 28a extending circumferentially along the inner peripheral edge of one axial side surface of the end plate 18, and four radial portions 28b extending radially outward from the annular portion 28a. The four radial portions 28b are arranged at equal angular intervals in the circumferential direction and are connected to the inner surface of the outer peripheral wall 20.

[0016] On the inner peripheral surface of the outer peripheral wall 20, a plurality of (12 in the illustrated embodiment) approximately rectangular parallelepiped engaging ridges 30 are arranged at equal angular intervals in the circumferential direction. The engaging ridges 30 protrude radially inward and extend linearly in the axial direction from one axial side surface of the end plate 18 to one axial end. An engaging recess 31 is defined between each pair of circumferentially adjacent engaging ridges 30. Therefore, a plurality of (12 in the illustrated embodiment) engaging recesses 31 are also arranged at equal angular intervals in the circumferential direction. When viewed from the axial direction, the radial portions 28b of the recesses 28 described above are connected to the inner surface of the outer peripheral wall 20 by the engaging recesses 31. Four axial locking projections 32 protruding radially inward are formed at one axial end of the inner peripheral surface of the outer peripheral wall 20 at equal angular intervals in the circumferential direction. When viewed from the axial direction, the axial locking projection 32 is aligned in the circumferential direction with the radial portion 28b of the recess 28, and as shown in the AA cross-sectional view of Figure 3(a), the axial locking projection 32 is arranged on one side of the engaging rib 30 in the axial direction. A single circumferential locking projection 34 that protrudes radially inward is also formed on one axial end of the inner peripheral surface of the outer circumferential wall 20. The circumferential locking projection 34 is also connected to one axial end face of one engaging rib 30.

[0017] Explaining this mainly with reference to FIG. 3(b), the shield body 16 has an overall thin, annular shape, and its outer peripheral surface is provided with a circumferential locking recess 36 consisting of a locally formed notch. A chamfered portion 38 having an arc-shaped vertical cross section and extending circumferentially is formed on one axial side of the outer peripheral surface of the shield body 16, except for the portion where the circumferential locking recess 36 is formed. A plurality of recesses 40 corresponding to the cross-sectional shape of the engaging ridges 30 of the main body 14 are formed at equal angular intervals in the circumferential direction on the outer peripheral edge of the other axial side of the shield body 16; more specifically, the same number as the number of engaging ridges 30 formed on the main body 14 (12 in the illustrated embodiment). A ring-shaped recess 41 extending circumferentially is formed on the inner peripheral edge of the other axial side of the shield body 16.

[0018] The shield body 16 is assembled to the main body 14 by forcing it axially relative to the main body 14. Specifically, the shield body 16 is first placed on one axial side of the main body 14. At this time, the circumferential positions of the circumferential locking recess 36 of the shield body 16 and the circumferential locking protrusion 34 of the main body 14 are aligned. Next, the shield body 16 is forced axially to the other side relative to the main body 14. In this manner, the outer peripheral edge of the shield body 16 elastically overcomes the axial locking protrusion 32 of the main body 14, and the chamfered portion 38 faces the axial locking protrusion 32, thereby locking the shield body 16 axially to the main body 14. Furthermore, the circumferential locking protrusion 34 of the main body 14 fits into the circumferential locking recess 36 of the shield body 16, and one axial end of the engaging ridge 30 of the main body 14 fits into the recess 40 of the shield body 16, thereby locking the shield body 16 circumferentially to the main body 14. Thus, the shield body 16 is assembled to the main body 14 .

[0019] The outer member 6 accommodates at least a portion of the inner member 4, and the outer member 6 and the inner member 4 are relatively rotatable about a common central axis o. As shown in the AA cross-sectional view in Fig. 1 , in the illustrated embodiment, the outer member 6 accommodates the entire inner member 4, and one axial end of the inner member 4 is fitted into the recess 41 of the shield body 16, while the other axial end of the inner member 4 is fitted into the annular portion 28a of the recess 28 of the main body 14, so that the inner member 4 is held by the outer member 6 so as to be relatively rotatable.

[0020] In the illustrated embodiment, the braking torque application means 8 is engaged with the outer member 6, is unable to rotate relative to the outer member 6, and applies a required braking torque to the relative rotation. Continuing the explanation with reference to FIG. 4 together with FIG. 1, in the illustrated embodiment, the braking torque application means 8 is in the shape of a thin ring. The braking torque application means 8 is made of metal and has an annular base 42 whose inner circumferential surface faces the outer circumferential surface 10 of the inner member 4. The base 42 is in the shape of a thin ring, and a plurality of action pieces 44 are provided at intervals in the circumferential direction on the inner circumferential edge of the base 42. The action pieces 44 extend radially inward and inclined toward one axial direction (one axial direction in the illustrated embodiment). In the illustrated embodiment, six action pieces 44 are provided, and each is designated by the reference numerals 44b to 44g. Here, in a preferred embodiment of the present invention, it is important that the inclination angle of the multiple action pieces 44 with respect to the axial direction and / or the extension length from the base 42 are different. In the illustrated embodiment, the action pieces 44b to 44g have different inclination angles with respect to the axial direction and different extension lengths from the base 42, with the extension lengths being 44b, 44d, 44f, 44e, 44c, and 44g in the order of longest. The arrangement of the action pieces 44b to 44g will be described later. The inner peripheral edge of the base 42 is further provided with a support piece 46 that extends axially beyond the action pieces 44b to 44g to one side in the axial direction (one axial side in the illustrated embodiment) and a receiving piece 48 that extends radially inward at a circumferential position where no action piece 44 is provided. Three support pieces 46 and three receiving pieces 48 are provided, and the action pieces 44, support pieces 46, and receiving pieces 48 are arranged at equal angular intervals in the circumferential direction. As shown in Figure 6, for example, in the braking torque applying means designated by reference numeral 8-1 in the figure, these are arranged in the following order from bottom to top on the page in the figure: action piece 44b, support piece 46, receiving piece 48, action piece 44e, action piece 44f, support piece 46, receiving piece 48, action piece 44c, action piece 44d, support piece 46, receiving piece 48, and action piece 44g (when comparing Figures 4, 5-1 and 5-2 with Figure 6, please note that in Figures 4, 5-1 and 5-2, the top and bottom of the pages of the FF cross section and GG cross section are reversed from the top and bottom of the pages of the BB cross section to EE cross section).That is, a pair of action pieces 44, 44 arranged adjacent to each other in the circumferential direction and a pair of support pieces 46 and receiving pieces 48 arranged adjacent to each other in the circumferential direction are alternately arranged in the circumferential direction. The pair of action pieces 44, 44 is configured by combining pieces with relatively short and long extension lengths. Therefore, the shortest action piece 44b and the longest action piece 44g, the second shortest action piece 44d and the second longest action piece 44c, and the third shortest action piece 44f and the third longest action piece 44e are arranged adjacent to each other in the circumferential direction. As a result, when the braking torque application means 8 is press-fitted into the inner member 4 and combined therewith, as described below, the press-fit load is dispersed in the circumferential direction, and rotation of the inner member 4 relative to the braking torque application means 8 is stabilized. Furthermore, the pair of support pieces 46 and receiving pieces 48 are arranged adjacent to each other in the circumferential direction.

[0021] A cylindrical reinforcing wall 50 is provided on the outer peripheral edge of the base 42, extending in one axial direction (one axial direction in the illustrated embodiment) and then extending radially outward. The height, i.e., the axial width, of the reinforcing wall 50 is equal to the height of the support piece 46, i.e., the axial extension length from the base 42. Twelve engaging pieces 52 projecting radially outward are arranged at equal angular intervals around the circumferential direction on the outer peripheral surface of the annular portion extending radially in the reinforcing wall 50. When viewed from the axial direction, the engaging piece 52 has a substantially rectangular shape, and the circumferential width of the engaging piece 52 corresponds to, i.e., is the same as or slightly narrower than, the circumferential width of the engaging recess 31 defined on the inner peripheral surface of the main body 14 of the outer member 6. A notch 54 used for positioning is formed on the outer surface of one of the twelve engaging pieces 52.

[0022] Such braking torque applying means 8 is press-fitted into the inner member 4 and assembled therewith before or after the inner member 4 is assembled with the outer member 6, and the inner surfaces of the extending ends of the action pieces 44 come into close contact with the outer peripheral surface 10 of the inner member 4. Here, in the torque limiter 2 which is a preferred embodiment of the present invention, as can be understood by referring to FIGS. 5-1, 5-2 and 6, the inclination angles of the multiple action pieces 44 with respect to the axial direction and / or the extension lengths from the base 42 of the multiple action pieces 44 are different, so that the inner surfaces of the multiple action pieces 44 are brought into close contact with the outer peripheral surface 10 of the inner member 4 at different axial positions. In the illustrated embodiment, the support pieces 46 and the receiving pieces 48 do not abut against the outer peripheral surface 10 of the inner member 4 but are separated therefrom. A lubricant such as grease is applied between the braking torque applying means 8 and the inner member 4.

[0023] The braking torque applying means 8 is further combined with the outer member 6 in a state where it cannot rotate relatively around the common central axis o by fitting the engagement pieces 52 into the above-mentioned engagement recesses 31 (of the outer member 6). As a result, when the inner member 4 and the outer member 6 rotate relatively around the common central axis o, the braking torque applying means 8 can apply a required braking torque to the relative rotation between the inner member 4 and the outer member 6 due to the close contact.

[0024] In the illustrated embodiment, three braking torque application means 8 are arranged stacked in the axial direction and are respectively indicated by the reference numerals 8-1 to 8-3. As can be understood by referring to Figures 5-1, 5-2 and 6, the three braking torque application means 8-1 to 8-3 are respectively combined with the outer member 6 with each being shifted in phase with the outer member 6, whereby the support piece 46 of one of the two braking torque application means 8 (i.e., braking torque application means 8-1 and 8-2, 8-2 and 8-3) arranged stacked in the axial direction and the receiving piece 48 of the other are arranged to be aligned in the circumferential direction. The braking torque applying means 8 and the outer member 6 are combined by fitting the engaging pieces 52 of the braking torque applying means 8 into the engaging recesses 31 of the outer member 6, and since both the engaging pieces 52 and the engaging recesses 31 are provided in multiple numbers (12 of each in the illustrated embodiment) at equal angular intervals in the circumferential direction, the phases of the three braking torque applying means 8-1 to 8-3 relative to the outer member 6 can be shifted by one by shifting the engaging recesses 31 into which the same engaging piece 52 is fitted in the circumferential direction.

[0025] When a rotational torque is applied to the inner member 4 and the outer member 6 from an external device connected to each of the inner member 4 and the outer member 6, causing them to rotate relatively around the central axis o, if the rotational torque is greater than the braking torque, the rotation is transmitted, but if the rotational torque is equal to or less than the braking torque, the rotation is not transmitted.

[0026]

[0033] Here, in the torque limiter 2 according to the preferred embodiment of the present invention, the inclination angles of the plurality of action pieces 44 relative to the axial direction and / or the extension lengths from the base 42 are different, so that the inner surfaces of the plurality of action pieces 44 are brought into close contact with the outer peripheral surface 10 of the inner member 4 at different axial positions, thereby preventing uneven wear of the outer peripheral surface 10 of the inner member 4 and extending the service life of the product. In the illustrated embodiment, a lubricant is further applied between the braking torque applying means 8 and the inner member 4, and the lubricant present in the sliding portion (in the illustrated embodiment, between the inner peripheral surfaces of the extending ends of the action pieces 44 and the outer peripheral surface of the inner member 4) may be repelled by the relative rotation. However, even if the lubricant is repelled by one sliding portion, it can transfer to another sliding portion, so that the lubricant is prevented from running out, thereby improving the wear resistance of the outer peripheral surface of the inner member 4.

[0027] 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 without departing from the spirit and scope of the present invention. For example, in the illustrated embodiment, the outer member 6 is provided with the engagement recess 31, and the braking torque application means 8 and the outer member 6 are combined in a state where they cannot rotate relative to each other. However, if desired, the inner member may be provided with the engagement recess, and the braking torque application means and the inner member may be combined in a state where they cannot rotate relative to each other. In this case, the braking torque application means has an annular base whose outer peripheral surface faces the cylindrical inner peripheral surface of the outer member. The outer peripheral edge of the base has a plurality of action pieces that extend radially outward at an inclination in one axial direction, and whose outer surfaces are in close contact with the inner peripheral surface of the outer member, and are spaced apart circumferentially. The materials of each component can be freely changed as appropriate. Furthermore, in the illustrated embodiment, the inclination angle of the multiple action pieces 44 relative to the axial direction and the extension length from the base 42 are changed, but if desired, only one of the inclination angle of the multiple action pieces 44 relative to the axial direction and the extension length from the base 42 may be changed. [Explanation of symbols]

[0028] 2: Torque limiter 4: Inner member 6:Outer member 8: Braking torque applying means 10: (Inner part) outer surface 42: Base 44: Working piece

Claims

1. The apparatus comprises an inner member that is rotatable relative to the outer member about a common central axis, an outer member that houses at least a portion of the inner member, and braking torque applying means that is engaged with the outer member, is unrotatable relative to the outer member, and applies a required braking torque to the relative rotation, In a torque limiter, the braking torque applying means comprises an annular base portion whose inner peripheral surface faces the cylindrical outer peripheral surface of the inner member, and the inner peripheral edge of the base portion is provided with a plurality of action pieces spaced apart in the circumferential direction, the action pieces extending radially inward at an inclination in one axial direction, and the inner surface of the extending end portion being in close contact with the outer peripheral surface of the inner member, A torque limiter characterized in that the plurality of action pieces have different inclination angles with respect to the axial direction and / or different extension lengths from the base.

2. 2. The torque limiter according to claim 1, wherein said braking torque applying means is in the form of a thin annular plate.

3. 2. The torque limiter according to claim 1, wherein a lubricant is applied between said braking torque applying means and said inner member.

4. 2. The torque limiter according to claim 1, wherein the plurality of action pieces have different inclination angles with respect to the axial direction and / or different extension lengths from the base portion.

5. the inner member is rotatable relative to the outer member about a common central axis, the outer member houses at least a portion of the inner member, and a braking torque applying means is engaged with the inner member, is unrotatable relative to the inner member, and applies a required braking torque to the relative rotation; In a torque limiter, the braking torque applying means has an annular base portion whose outer peripheral surface faces the cylindrical inner peripheral surface of the outer member, and the outer peripheral edge of the base portion is provided with a plurality of action pieces spaced apart in the circumferential direction, the action pieces extending radially outward at an inclination in one axial direction, the outer surfaces of the extending ends of which are in close contact with the inner peripheral surface of the outer member, A torque limiter characterized in that the plurality of action pieces have different inclination angles with respect to the axial direction and / or different extension lengths from the base.

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