Torque limiter

Abstract

To enable stable lubrication of a torque limiter while increasing space efficiency with suppression of cost increase.SOLUTION: A torque limiter limits torque, which is transmitted between a driving side and a driven side, to predetermined limit torque or below. The torque limiter includes: a hollow outside transmission member that is coaxially fixed to an inner peripheral surface of a rotor of an electric motor; a hollow inside transmission member that is coaxially arranged within the outside transmission member; a frictional engagement part that frictionally engages the outside and inside transmission members with each other within the rotor; an inside passage that is formed in the inside transmission member so as to guide a lubrication medium, supplied into the inside transmission member, to the frictional engagement part; and an outside passage that is formed in the outside transmission member so as to guide the lubrication medium, passing through the frictional engagement part, to the rotor side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a torque limiter that limits torque transmitted between a driving side and a driven side. [Background technology]

[0002] Conventionally, there is known an electric motor that includes a stator, a rotor, an output element for outputting torque from the rotor, and a slip clutch (torque limiter) that is provided between the rotor and the output element and limits the maximum transmittable torque (see, for example, Patent Document 1). The slip clutch of this electric motor has a spring element clamped between two opposite friction surfaces that are fixed in the axial direction, and the spring element presses two opposing friction surfaces that are spaced apart from each other against the corresponding opposite friction surfaces to bring them into frictional engagement. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 254562 Summary of the Invention [Problem to be solved by the invention]

[0004] In the torque limiter described above, there is a risk that the torque transmitted by the torque limiter may become unstable due to changes in the lubrication state between the opposite friction surfaces. Therefore, in order to stabilize the torque transmitted by the torque limiter, it is necessary to stably supply a lubricating medium to the torque limiter. However, Patent Document 1 does not disclose or suggest a lubrication structure for the torque limiter.

[0005] Therefore, a main object of the present disclosure is to enable stable lubrication of a torque limiter while suppressing increases in costs and improving space efficiency. [Means for solving the problem]

[0006] The torque limiter disclosed herein limits the torque transmitted between a driving side and a driven side to a predetermined limit torque or less, and includes a hollow outer transmission member fixed coaxially to the inner surface of the rotor of an electric motor, a hollow inner transmission member arranged coaxially inside the outer transmission member, a frictional engagement portion that frictionally engages the outer transmission member and the inner transmission member inside the rotor, an inner passage formed in the inner transmission member to guide a lubricating medium supplied inside the inner transmission member to the frictional engagement portion, and an outer passage formed in the outer transmission member to guide the lubricating medium that has passed through the frictional engagement portion toward the rotor.

[0007] The torque limiter disclosed herein includes a hollow outer transmission member coaxially fixed to the inner circumferential surface of the rotor of an electric motor, a hollow inner transmission member coaxially disposed within the outer transmission member, and a frictional engagement portion that frictionally engages the outer transmission member and the inner transmission member within the rotor. A lubricant is supplied to the inner transmission member and guided to the frictional engagement portion within the rotor through an inner passage formed in the inner transmission member. Furthermore, the lubricant that passes through the frictional engagement portion is guided to the rotor through an outer passage formed in the outer transmission member. As a result, the lubrication path for supplying the lubricant to the frictional engagement portion is included in the lubrication path for supplying the lubricant to the rotor of the electric motor, eliminating the need for a dedicated lubrication structure for supplying the lubricant to the frictional engagement portion. This enables stable lubrication of the torque limiter while suppressing cost increases and improving space efficiency. Furthermore, stable lubrication of the torque limiter, i.e., the frictional engagement portion, effectively suppresses variations in the static and dynamic friction coefficients and the generation of wear debris in the frictional engagement portion. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram illustrating a vehicle equipped with a drive unit including a torque limiter according to the present disclosure. [Figure 2] FIG. 1 is a cross-sectional view showing a torque limiter according to the present disclosure. [Figure 3] FIG. 10 is a cross-sectional view showing another torque limiter of the present disclosure. [Figure 4] FIG. 10 is a cross-sectional view showing yet another torque limiter of the present disclosure. [Figure 5] FIG. 10 is a cross-sectional view showing another torque limiter of the present disclosure. [Figure 6] FIG. 10 is a cross-sectional view showing yet another torque limiter of the present disclosure. [Figure 7] FIG. 10 is a cross-sectional view showing another torque limiter of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1 is a schematic diagram showing a vehicle V equipped with a drive unit 5 including a torque limiter 1 according to the present disclosure. The vehicle V is an electric vehicle using a motor generator (rotating electric machine) MG as a drive source, and the drive unit 5 outputs power from the motor generator MG to a pair of drive shafts (output shafts) DS connected to a pair of left and right drive wheels DW of the vehicle V. As shown in FIG. 1, the drive unit 5 includes, in addition to the motor generator MG, a gear train 6 that transmits power (torque) between the motor generator MG and the pair of drive shafts DS, and a case 7 that houses the motor generator MG and the gear train 6.

[0011] The motor generator MG is a synchronous generator motor (three-phase AC motor) including a stator S and a rotor R, and exchanges power with an electricity storage device (battery, not shown) via an inverter (not shown). The motor generator MG is driven by power from the electricity storage device to operate as an electric motor that generates drive torque, and also outputs regenerative braking torque when braking the vehicle V. The stator S includes an annular stator core and three (three-phase) stator coils wound around the stator core, and is fastened (fixed) to a case 7 via a plurality of bolts (not shown). The rotor R includes an annular rotor core and the like, and is coaxially connected to a hollow cylindrical input shaft IS via a torque limiter 1.

[0012] The gear train 6 includes a differential gear 65 having a counter drive gear 61, a counter driven gear 62, a drive pinion gear (final drive gear) 63, and a differential ring gear (final driven gear) 64. The counter drive gear 61 is an externally toothed gear that rotates integrally with the input shaft IS. The counter drive gear 61 may be molded integrally with the input shaft IS, or a separate counter drive gear 61 may be fixed to the input shaft IS.

[0013] The counter driven gear 62 is an external gear with a larger diameter than the counter drive gear 61 and meshes with the counter drive gear 61. The counter driven gear 62 rotates integrally with the counter shaft CS, which is supported by the case 7 so as to be rotatable parallel to the input shaft IS and the pair of drive shafts DS. The drive pinion gear 63 is an external gear with a smaller diameter than the counter driven gear 62 and is molded integrally with the counter shaft CS, for example, so as to be located on the opposite side of the counter driven gear 62. As a result, the drive pinion gear 63 is coaxial with the counter driven gear 62 and the counter shaft CS and rotates integrally with them. However, a drive pinion gear 63 separate from the counter shaft CS may be fixed to the counter shaft CS.

[0014] The differential ring gear 64 is an external gear that meshes with the drive pinion gear 63. The differential gear 65 includes a pair (two pieces) of pinion gears, a pair (two pieces) of side gears that are each fixed to the drive shaft DS and mesh with the pair of pinion gears, a pinion shaft that supports the pair of pinion gears, and a differential case (all of which are not shown) that houses the pair of pinion gears and the pair of side gears and to which the differential ring gear 64 is connected (fixed).

[0015] The case 7 is formed by fastening together, for example, a housing, a case body, and a cover. In this embodiment, the housing, case body, and cover are all cast aluminum alloy products. Oil (hydraulic oil) is supplied as a lubricating and cooling medium to the motor generator MG, gear train 6, bearings (not shown), and other components housed within the case 7. In other words, the interior of the case 7 is a space into which oil is supplied.

[0016] FIG. 2 is a cross-sectional view showing a torque limiter 1 of the present disclosure included in a drive device 5. In this embodiment, the torque limiter 1 is disposed between a rotor R (first rotating member) of a motor generator MG serving as a drive source and an input shaft IS (second rotating member) to which power is transmitted from the rotor R. The torque limiter 1 allows transmission of torque equal to or less than a predetermined limit torque (specified value) Tlim between the rotor R on the drive side and the input shaft IS on the driven side, and causes slippage between the rotor R and the input shaft IS in response to an increase in the torque transmitted to the rotor R or the input shaft IS. As shown in FIG. 2, the torque limiter 1 includes a hollow outer transmission member 10 coaxially fixed to the inner circumferential surface of the rotor R of the motor generator MG, and a hollow inner transmission member 20 coaxially disposed inside the outer transmission member 10 and coupled (fixed) to the input shaft IS so as to rotate integrally therewith.

[0017] As shown in the figure, the outer transmission member 10 includes a first transmission member (one-side transmission member) 11, a second transmission member (other-side transmission member) 12, and a tightening mechanism 15. The first transmission member 11 is a hollow tubular body made of metal such as steel, and includes a substantially cylindrical tubular portion 110 and an extending tubular portion 111 extending from the tubular portion 110. The end of the tubular portion 110 on the opposite side to the input shaft IS side (left side in FIG. 2) is rotatably supported by the case 7 via a bearing (not shown). In addition, an annular tapered surface (second annular tapered surface) 112 is formed on the inner circumferential surface of the end of the tubular portion 110 on the input shaft IS side (right side in FIG. 2). The annular tapered surface 112 is an inverted conical surface (inverted tapered surface) whose central axis is the axis of the first transmission member 11, i.e., the rotation axis of the rotor R (see dotted line in Figure 2), and which expands in diameter from the end opposite the extended cylindrical portion 111 side (left side in Figure 2) toward the extended cylindrical portion 111 side (right side in Figure 2).

[0018] The extending tubular portion 111 extends in the axial direction from the outer periphery of the end face of the tubular portion 110 on the input shaft IS side (right side in FIG. 2 ), and has an inner diameter larger than the inner diameter of the tubular portion 110. In addition, at least one outflow passage (outer passage) 115 is formed in the extending tubular portion 111 of the first transmission member 11. The outflow passage 115 is a through hole (oil hole) that penetrates the extending tubular portion 111 in the radial direction, and opens at the inner circumferential surface of the extending tubular portion 111 near the end face of the tubular portion 110 on the input shaft IS side, and also opens at the outer circumferential surface of the extending tubular portion 111. A plurality of outflow passages 115 may be formed in the extending tubular portion 111 at intervals in the circumferential direction of the outer transmission member 10, or only one outflow passage 115 may be formed in the extending tubular portion 111. Furthermore, at least one groove (recess) 117 that communicates with the outflow passage 115 and extends in the axial direction is formed on the outer peripheral surfaces of the cylindrical portion 110 and the extending cylindrical portion 111. The outer transmission member 10 has an abutment portion that abuts against one axial end portion (the left end portion in FIG. 2) of the rotor R, and a key (not shown) that fits into a key groove formed in the rotor R, and is fixed to the inner peripheral surface of the rotor R by shrink fitting.

[0019] The second transmission member 12 is a tubular body made of metal such as steel, and as shown in FIG. 2, includes a substantially cylindrical tubular portion 120 and an extending tubular portion 121 extending from the tubular portion 120. The tubular portion 120 of the second transmission member 12 has an inner diameter that is the same as the inner diameter of the tubular portion 110 of the first transmission member 11 and an outer diameter that is slightly smaller than the inner diameter of the extending tubular portion 111 of the first transmission member 11. The extending tubular portion 121 of the second transmission member 12 has an inner diameter that is the same as the inner diameter of the tubular portion 120 and an outer diameter that is smaller than the outer diameter of the tubular portion 120. In addition, an annular tapered surface (third annular tapered surface) 123 is formed on the inner circumferential surface of the end of the tubular portion 120 on the side opposite to the input shaft IS side (left side in FIG. 2). The annular tapered surface 123 is an inverted conical surface (inverted tapered surface) with its central axis being the axis of the second transmission member 12, i.e., the rotation axis of the rotor R, and its diameter decreases as it moves from the end opposite the extending cylindrical portion 121 side (left side in Figure 2) toward the end on the extending cylindrical portion 121 side (right side in Figure 2).

[0020] The second transmission member 12 is fitted (inserted) into the extending tubular portion 111 of the first transmission member 11, and the first and second transmission members 11, 12 are tightened in the axial direction by a tightening mechanism 15. As shown in FIG. 2 , the tightening mechanism 15 includes an annular disc spring 151 as an elastic member, an annular pressing member 152, and a plurality of bolts 155. The disc spring 151 is disposed around the extending tubular portion 121 of the second transmission member 12 and radially inside the extending tubular portion 111 of the first transmission member 11 so as to abut against the end surface of the tubular portion 120 of the second transmission member 12. The pressing member 152 is disposed around the extending tubular portion 121 of the second transmission member 12 so as to abut against the end surface of the extending tubular portion 111 of the first transmission member 11 and the disc spring 151. That is, the disc spring 151 is disposed between the second transmission member 12 and the pressing member 152 so as to be located radially inside the abutting portion between the pressing member 152 and the extending cylindrical portion 111 of the first transmission member 11.

[0021] The plurality of bolts 155 are inserted into corresponding through holes formed in the pressing member 152 so that their heads abut against the pressing member 152, and are screwed into corresponding screw holes formed in the extending tubular portion 111 of the first transmission member 11. As a result, the first and second transmission members 11, 12 are fastened by the axial force of the plurality of bolts 155 via the disc spring 151 and the pressing member 152, and the second transmission member 12 is biased by the disc spring 151. In addition, in this embodiment, as shown in FIG. 2 , the pressing member 152 abuts against the axial end face of the rotor R on the input shaft IS side, and restricts axial movement of the rotor R relative to the outer transmission member 10 (movement toward the input shaft IS side).

[0022] The inner transmission member 20 is a tubular body made of metal such as steel, and includes, as shown in Fig. 2, a substantially cylindrical tubular portion 200 and an annular protrusion 201 protruding radially outward from the outer circumferential surface of the tubular portion 200. A spline is formed on the outer circumferential surface of one end (the end on the right side in Fig. 2) of the tubular portion 200, and the inner transmission member 20 is coupled to the input shaft IS via the spline so as to rotate integrally therewith. In addition, a pair of annular tapered surfaces (first annular tapered surfaces) 201a, 201b are formed on the protrusion 201 of the inner transmission member 20 so as to be inclined in opposite directions to each other in the extension direction of the rotation axis of the inner transmission member 20.

[0023] The annular tapered surface 201a is a conical surface whose central axis is the rotation axis of the rotor R or the like, and whose diameter increases from the end opposite the input shaft IS side (left side in FIG. 4) toward the end opposite the input shaft IS side (right side in FIG. 2). The annular tapered surface 201b is a conical surface whose central axis is the rotation axis of the rotor R or the like, and whose diameter decreases from the end opposite the input shaft IS side (left side in FIG. 2) toward the end opposite the input shaft IS side (right side in FIG. 4). In this embodiment, the annular tapered surfaces 201a and 201b are formed symmetrically with respect to a plane that passes through the center of the protrusion 201 in the axial direction and is perpendicular to the rotation axis of the rotor R. That is, the axial length of the annular tapered surface 201a is the same as the axial length of the annular tapered surface 201b, and the apex angle of the cone that defines the annular tapered surface 201a is the same as the apex angle of the cone that defines the annular tapered surface 201b. Furthermore, the apex angle of the cone defining the annular tapered surface 201a is the same as the apex angle of the cone defining the annular tapered surface 112 of the first transmission member 11, and the apex angle of the cone defining the annular tapered surface 201b is the same as the apex angle of the cone defining the annular tapered surface 123 of the second transmission member 12.

[0024] In this embodiment, the axial length of the annular tapered surface 201a is shorter than the axial length of the annular tapered surface 112 of the first transmitting member 11, and the axial length of the annular tapered surface 201b is shorter than the axial length of the annular tapered surface 123 of the second transmitting member 12. That is, the area of ​​the annular tapered surface 201a is smaller than the area of ​​the annular tapered surface 112, and the area of ​​the annular tapered surface 201b is smaller than the area of ​​the annular tapered surface 123. In addition, in this embodiment, the hardness of the pair of annular tapered surfaces 201a and 201b is set lower than the hardness of the annular tapered surfaces 112 and 123 by changing the heat treatments performed on the annular tapered surfaces 112 and 123 and the annular tapered surfaces 201a and 201b, or by using different materials for the first and second transmitting members 11 and 12 and the inner transmitting member 20. In this embodiment, each of the annular tapered surfaces 201a and 201b has a plurality of grooves (not shown) formed at intervals in the circumferential direction and extending in the direction of the generatrix of the annular tapered surface 201a or 201b. However, instead of the plurality of grooves, a plurality of friction materials may be attached to each of the annular tapered surfaces 201a and 201b at intervals in the circumferential direction, or a friction material having a plurality of grooves may be attached.

[0025] Furthermore, two annular recesses 202a and 202b are formed on the outer peripheral surface of the inner transmission member 20 (cylindrical portion 200). The annular recess 202a extends along the inner peripheral portion (inner peripheral edge) 201i of the annular tapered surface 201a, and the annular recess 202b extends along the inner peripheral portion (inner peripheral edge) 201i of the annular tapered surface 201b. In addition, a first inner passage 205a and a second inner passage 205b are formed in the inner transmission member 20 (cylindrical portion 200). The first inner passage 205a is a through-hole (oil hole) that extends in the radial direction of the cylindrical portion 200 and penetrates the cylindrical portion 200, and opens at the inner peripheral surface of the cylindrical portion 200 and at the bottom surface of the annular recess 202a. The second inner passage 205b is a through-hole (oil hole) that extends radially of the cylindrical portion 200 and penetrates the cylindrical portion 200, and opens at the inner circumferential surface of the cylindrical portion 200 and at the bottom surface of the annular recess 202b. A plurality of the first and second inner passages 205a, 205b may be formed in the cylindrical portion 200 at intervals in the circumferential direction of the inner transmission member 20, or one of each may be formed in the cylindrical portion 200.

[0026] 2, the end of the inner transmission member 20 on the opposite side to the input shaft IS side (the left side in FIG. 2) is fitted (inserted) into the first transmission member 11 of the outer transmission member 10 so that the annular tapered surface 201a of the protrusion 201 abuts against the annular tapered surface 112 and the annular tapered surface 201b of the protrusion 201 is surrounded by the extending tubular portion 111. Furthermore, the second transmission member 12 of the outer transmission member 10 is fitted (inserted) into the extending tubular portion 111 of the first transmission member 11 so that the annular tapered surface 123 abuts against the annular tapered surface 201b of the protrusion 201. Furthermore, the tubular portion 120 of the second transmission member 12 engages with the key 14 held by the extending tubular portion 111 as a rotation stopper.

[0027] As a result, the key 14 restricts rotation of the second transmission member 12 relative to the first transmission member 11, and the second transmission member 12 is supported by the first transmission member 11 so as to rotate integrally therewith, and is connected to the input shaft IS via the first transmission member 11 so as to rotate integrally therewith. However, the first transmission member 11 and the second transmission member 12 may be connected so as to rotate integrally via a spline. The first and second transmission members 11, 12 are then tightened by the tightening mechanism 15 so that the annular tapered surface 112 comes into close contact with the annular tapered surface 201a of the inner transmission member 20, and so that the annular tapered surface 123 comes into close contact with the annular tapered surface 201b. As a result, the protrusion 201, i.e., the annular tapered surfaces 201a, 201b, of the inner transmission member 20 is surrounded by the outer transmission member 10, i.e., the first and second transmission members 11, 12, inside the rotor R, and the end of the inner transmission member 20 on the input shaft IS side (right side in Figure 2) protrudes from the outer transmission member 10.

[0028] Furthermore, when the cylindrical portion 110 of the first transmission member 11 and the cylindrical portion 120 of the second transmission member 12 are fastened by the fastening mechanism 15, an annular passage (outer passage) 105 is defined radially outward from an outer periphery (outer peripheral edge) 112o of the annular tapered surface 112 and an outer periphery 123o of the annular tapered surface 123. As shown in Fig. 2, the annular passage 105 communicates with an outflow passage 115 formed in the extending cylindrical portion 111, and also communicates with the gap between the annular tapered surfaces 201a and 112, the gap between the annular tapered surfaces 201b and 123, and the plurality of grooves formed in the annular tapered surfaces 201a and 201b. Furthermore, when the first transmission member 11 and the second transmission member 12 are tightened by the tightening mechanism 15, as shown in FIG. 2, the annular recess 202a of the inner transmission member 20, the inner circumferential surface of the first transmission member 11 (cylindrical portion 110), and a portion of the annular tapered surface 112 define an annular space, and the annular recess 202b of the inner transmission member 20, the inner circumferential surface of the second transmission member 12 (cylindrical portion 120), and a portion of the annular tapered surface 123 also define an annular space.

[0029] While the vehicle V including the torque limiter 1 configured as described above is traveling, if the torque output from the motor generator MG to the rotor R and the outer transmission member 10 or the torque transmitted from the drive wheels DW to the input shaft IS becomes equal to or less than the limit torque Tlim, the annular tapered surface 201a and the annular tapered surface 112 frictionally engage with each other without slipping, and the annular tapered surface 201b and the annular tapered surface 123 also frictionally engage with each other without slipping. That is, the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123 form a frictional engagement portion that frictionally engages the outer transmission member 10 and the inner transmission member 20 inside the rotor R. This causes the outer transmission member 10, i.e., the first and second transmission members 11, 12, and the inner transmission member 20, to rotate integrally, allowing transmission of torque equal to or less than the limit torque Tlim between the rotor R and the input shaft IS. In this embodiment, the limit torque Tlim is determined by the tightening torque of the bolt 155, the rigidity of the disc spring 151, the contact area and friction coefficient between the annular tapered surface 201a and the annular tapered surface 112, the contact area and friction coefficient between the annular tapered surface 201b and the annular tapered surface 123, etc.

[0030] In contrast, when the torque output from motor generator MG to rotor R and outer transmission member 10 or the torque transmitted from the drive wheels DW side to input shaft IS exceeds the limit torque Tlim, slippage occurs between annular tapered surface 201a and annular tapered surface 112, and between annular tapered surface 201b and annular tapered surface 123, which serve as frictional engagement portions. This makes it possible to effectively prevent excessive torque from being transmitted from motor generator MG to input shaft IS, or excessive torque from being transmitted from drive wheels DW to motor generator MG.

[0031] The torque limiter 1 can ensure a sufficient contact area between the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123 while suppressing an increase in the outer diameter of the outer transmission member 10, i.e., the first and second transmission members 11, 12, and the inner transmission member 20. Therefore, by applying a sufficient tightening force to the first and second transmission members 11, 12 by the tightening mechanism 15, it is possible to sufficiently ensure the limit torque Tlim, which is the upper limit of torque that does not cause slippage between the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123. As a result, the torque limiter 1 can sufficiently ensure the limit torque Tlim while suppressing an increase in size of the torque limiter 1 and, ultimately, the drive unit 5 including it.

[0032] Furthermore, while the vehicle V including the torque limiter 1 is traveling, oil as a lubricating / cooling medium that has flowed down into the case 7 is scooped up by the differential ring gear 64 and the like, and is guided into the hollow input shaft IS by a guide portion (not shown) formed in the case 7. The oil that has been guided into the input shaft IS flows into the inner transmission member 20, and is guided to the friction engagement portions, i.e., the gap between the annular tapered surfaces 201a and 112 and the gap between the annular tapered surfaces 201b and 123, via first and second inner passages 205a, 205b formed in the inner transmission member 20 (cylindrical portion 200). Furthermore, the oil passes through the gap between the annular tapered surfaces 201a and 112, the gap between the annular tapered surfaces 201b and 123, and the multiple grooves formed in the annular tapered surfaces 201a and 201b, and is guided to the rotor R via the annular passage 105 between the first and second transmission members 11 and 12 in the axial direction, and the outflow passage 115 and groove 117 of the first transmission member 11.

[0033] That is, in torque limiter 1, a lubrication path for supplying oil as a lubricating / cooling medium to the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123 that form the friction engagement portion is included midway in a lubrication path for supplying oil as a lubricating / cooling medium to the rotor R of motor generator MG. This eliminates the need for a dedicated lubrication structure for supplying oil to the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123. As a result, it is possible to stably lubricate and cool torque limiter 1 while suppressing costs and improving space efficiency. Furthermore, by stably lubricating the torque limiter 1, i.e., the pair of annular tapered surfaces 201a, 201b and the annular tapered surfaces 112, 123, it is possible to effectively suppress variations in the static and dynamic friction coefficients between the annular tapered surface 201a and the annular tapered surface 112, and between the annular tapered surface 201b and the annular tapered surface 123, as well as the generation of wear debris.

[0034] Furthermore, in the torque limiter 1, the first inner passage 205a of the inner transmission member 20 guides oil to the inner circumferential portion 201i of one annular tapered surface 201a, and the second inner passage 205b guides oil to the inner circumferential portion 201i of the other annular tapered surface 201b. This allows the oil supplied to the first and second inner passages 205a, 205b to be well distributed throughout the gap between the annular tapered surfaces 201a and 112 and the gap between the annular tapered surfaces 201b and 123 due to centrifugal force generated in response to rotation of the rotor R, the outer transmission member 10, and the inner transmission member 20.

[0035] Furthermore, the first and second inner passages 205a, 205b each extend in the radial direction of the inner transmission member 20. This allows the oil supplied to the inside of the inner transmission member 20 to be smoothly supplied by the gap between the annular tapered surfaces 201a and 112 and the gap between the annular tapered surfaces 201b and 123. However, the first and second inner passages 205a, 205b may be formed in the inner transmission member 20 so as to be inclined with respect to the radial direction of the inner transmission member 20.

[0036] Furthermore, in the torque limiter 1, the first and second transmission members 11, 12 define an annular passage 105 as an outer passage radially outward from the outer circumferential portion 112o of the annular tapered surface 112 and the outer circumferential portion 123o of the annular tapered surface 123, and the outflow passage 115 of the first transmission member 11 communicates with the annular passage 105 and extends in the radial direction of the outer transmission member 10 (rotor R). This allows oil that has flowed out from the gap between the annular tapered surfaces 201a and 112 and the gap between the annular tapered surfaces 201b and 123 to be collected in the annular passage 105 and supplied to the rotor R via the outflow passage 115 by centrifugal force.

[0037] Furthermore, in torque limiter 1, wear powder generated between annular tapered surfaces 201a and 112 is collected in a radially inner annular recess (annular space) 202a to prevent it from being discharged to the outside, and wear powder generated between annular tapered surfaces 201b and 123 is collected in a radially inner annular recess (annular space) 202b to prevent it from being discharged to the outside. In addition, in torque limiter 1, wear powder can be collected in annular passage 105 between first and second transmission members 11 and 12 in the axial direction to prevent it from being discharged to the outside.

[0038] Furthermore, in the torque limiter 1, the hardness of the pair of annular tapered surfaces 201a, 201b is set to be lower than the hardness of the annular tapered surfaces 112, 123. Furthermore, the area of ​​the annular tapered surface 201a is set to be smaller than the area of ​​the annular tapered surface 112, and the area of ​​the annular tapered surface 201b is set to be smaller than the area of ​​the annular tapered surface 123. As a result, since the annular tapered surfaces 201a, 201b, which have smaller areas, wear due to contact with the annular tapered surfaces 112, 123, depressions are formed at the contact portion between the annular tapered surface 112, which has a larger area, and the annular tapered surface 201a, and at the contact portion between the annular tapered surface 123, which has a larger area, and the annular tapered surface 201b, and this effectively prevents wear powder from accumulating in the depressions. However, the hardness of the annular tapered surfaces 112 and 123 may be set lower than the hardness of the pair of annular tapered surfaces 201a and 201b in the torque limiter 1. In this case, it is preferable that the area of ​​the annular tapered surface 112 is set smaller than the area of ​​the annular tapered surface 201a, and the area of ​​the annular tapered surface 123 is set smaller than the area of ​​the annular tapered surface 201b.

[0039] Furthermore, in the torque limiter 1, the pressing member 152 of the tightening mechanism 15 abuts against the axial end face of the rotor R on the input shaft IS side, restricting axial movement of the rotor R (movement toward the input shaft IS side) relative to the outer transmission member 10. This eliminates the need to separately prepare an end plate that restricts axial movement of the rotor R relative to the outer transmission member 10, making it possible to suppress an increase in the number of parts in the drive device 5 including the motor generator MG and the torque limiter 1.

[0040] 3 is a cross-sectional view showing another torque limiter 1B of the present disclosure. Note that, among the components of the torque limiter 1B, the same elements as those of the torque limiter 1 described above are given the same reference numerals, and redundant explanations will be omitted.

[0041] 3 includes a hollow outer transmission member 10 that is coaxially fixed to the inner circumferential surface of the rotor R, and a hollow inner transmission member 20B that is coaxially disposed inside the outer transmission member 10 and is coupled (fixed) to the input shaft IS so as to rotate integrally therewith. Furthermore, the outer transmission member 10 of the torque limiter 1B includes a first transmission member (one-side transmission member) 11 that has an annular tapered surface (second annular tapered surface) 112, a second transmission member (other-side transmission member) 12 that has an annular tapered surface (third annular tapered surface) 123, and a tightening mechanism 15.

[0042] Furthermore, the inner transmission member 20B of the torque limiter 1B includes a pair of annular tapered surfaces (first annular tapered surfaces) 201a, 201b, at least one first inner passage 205a, and at least one second inner passage 205b. The first inner passage 205a is a through-hole (oil hole) that extends in the radial direction of the inner transmission member 20 and passes through the cylindrical portion 200, and opens at the inner circumferential surface of the cylindrical portion 200 and also opens at the annular tapered surface 201a. The second inner passage 205b is a through-hole (oil hole) that extends in the radial direction of the rotor R (cylindrical portion 200) and passes through the cylindrical portion 200, and opens at the inner circumferential surface of the cylindrical portion 200 and also opens at the annular tapered surface 201b.

[0043] In this torque limiter 1B as well, it is possible to ensure that the oil (lubricating / cooling medium) supplied to the first and second inner passages 205a, 205b is adequately distributed throughout the gap between the annular tapered surfaces 201a and 112, which serve as frictional engagement parts, and the gap between the annular tapered surfaces 201b and 123. However, in the torque limiter 1B as well, the first and second inner passages 205a, 205b may be formed in the inner transmission member 20 so as to be inclined with respect to the radial direction of the inner transmission member 20.

[0044] 4 is a cross-sectional view showing still another torque limiter 1C of the present disclosure. Note that, among the components of the torque limiter 1C, the same elements as those of the torque limiter 1 described above are given the same reference numerals, and redundant explanations will be omitted.

[0045] 4 includes a hollow outer transmission member 10C that is coaxially fixed to the inner circumferential surface of the rotor R, and a hollow inner transmission member 20C that is coaxially disposed inside the outer transmission member 10C and is coupled (fixed) to the input shaft IS so as to rotate integrally therewith. Furthermore, the outer transmission member 10C of the torque limiter 1C includes a first transmission member (one-side transmission member) 11C having an annular tapered surface (second annular tapered surface) 112, a second transmission member (other-side transmission member) 12 having an annular tapered surface (third annular tapered surface) 123, and a tightening mechanism 15.

[0046] The inner transmission member 20C of the torque limiter 1C includes a pair of annular tapered surfaces (first annular tapered surfaces) 201a, 201b, at least one first inner passage 205a, and at least one second inner passage 205b. The first inner passage 205a is a through-hole (oil hole) that extends in a direction intersecting the annular tapered surface 201a (in the example of FIG. 4, a direction perpendicular to the annular tapered surface 201a) and penetrates the cylindrical portion 200 and the protruding portion 201, and opens at the inner circumferential surface of the cylindrical portion 200 and at the annular tapered surface 201a. The second inner passage 205b extends in a direction intersecting the annular tapered surface 201b (in the example of FIG. 4, a direction perpendicular to the annular tapered surface 201b) and opens at the annular tapered surface 201a and at the first inner passage 205a.

[0047] Furthermore, a second outflow passage 115C is formed in the first transmission member 11C of the outer transmission member 10C in addition to the outflow passage 115. The second outflow passage 115C is a through-hole (oil hole) that extends in a direction intersecting the annular tapered surface 112 (in the example of FIG. 4, a direction perpendicular to the annular tapered surface 112) and penetrates the tubular portion 110, and communicates with the groove 117. The second outflow passage 115C opens at the annular tapered surface 112 so as to face the opening end of the first inner passage 205a in the annular tapered surface 201a.

[0048] In this torque limiter 1C as well, it is possible to ensure that the oil (lubricating / cooling medium) supplied to the first and second inner passages 205a, 205b is adequately distributed throughout the gap between the annular tapered surfaces 201a and 112 and the gap between the annular tapered surfaces 201b and 123, which serve as frictional engagement parts. Furthermore, by forming the second outflow passage 115C in the outer transmission member 10C, it is possible to increase the amount of oil supplied as a lubricating / cooling medium to the rotor R. Furthermore, by making the first and second inner passages 205a, 205b and the second outflow passage 115C intersect (orthogonal to) the annular tapered surfaces 201a, 201b or 112, it is possible to further improve the workability when forming the first and second inner passages 205a, 205b and the second outflow passage 115C in the inner transmission member 20C (the cylindrical portion 200 and the protruding portion 201) or the first transmission member 11C (the cylindrical portion 110).

[0049] 5 is a cross-sectional view showing another torque limiter 1D of the present disclosure. Note that, among the components of the torque limiter 1D, the same elements as those of the torque limiter 1 described above are given the same reference numerals, and redundant explanations will be omitted.

[0050] 5 includes a hollow outer transmission member 10D that is coaxially fixed to the inner circumferential surface of the rotor R, and a hollow inner transmission member 20D that is coaxially disposed inside the outer transmission member 10D and is coupled (fixed) to the input shaft IS so as to rotate integrally therewith. Furthermore, the outer transmission member 10D of the torque limiter 1D includes a first transmission member (one-side transmission member) 11D having an annular tapered surface (second annular tapered surface) 112, a second transmission member (other-side transmission member) 12D having an annular tapered surface (third annular tapered surface) 123, and a tightening mechanism 15 that tightens the first and second transmission members 11D, 12D in the axial direction.

[0051] The inner transmission member 20D of the torque limiter 1D includes a substantially cylindrical tubular portion (tubular body) 200D having at least one first inner passage 205a and at least one second inner passage 205b, and an annular member 201D having a pair of annular tapered surfaces (first annular tapered surfaces) 201a, 201b and fixed to the tubular portion 200D so as to rotate integrally with the tubular portion 200D. The annular member 201D corresponds to the protrusion 201 of the inner transmission member 20 or the like separated from the tubular portion 200, and has splines formed on its inner circumferential surface. The tubular portion 200D, which has splines formed on its outer circumferential surface, is spline-fitted with the annular member 201D.

[0052] The first inner passage 205a of the cylindrical portion 200D extends in the radial direction of the inner transmission member 20D so as to guide oil to the inner circumferential portion 201i of the annular tapered surface 201a, and the second inner passage 205b extends in the radial direction of the inner transmission member 20D so as to guide oil to the inner circumferential portion 201i of the annular tapered surface 201b. Furthermore, an annular recess 114 for collecting wear powder is formed on the inner circumferential surface of the first transmission member 11D (cylindrical portion 110) of the torque limiter 1D, extending along the inner circumferential portion 201i of the annular tapered surface 201a and the inner circumferential portion of the annular tapered surface 112. Furthermore, an annular recess 124 for collecting wear powder is formed on the inner circumferential surface of the second transmission member 12D of the torque limiter 1D, extending along the inner circumferential portion 201i of the annular tapered surface 201b and the inner circumferential portion of the annular tapered surface 123.

[0053] The torque limiter 1D can also achieve the same effects as the torque limiter 1 described above. Furthermore, in the torque limiter 1D, the first transmission member 11D and the second transmission member 12D of the outer transmission member 10D are fastened by the fastening mechanism 15 to hold the annular member 201D between the annular tapered surfaces 112 and 123, and then the cylindrical portion 200D can be fitted to the annular member 201D. This can further improve the ease of assembly of the torque limiter 1D. Note that, in the torque limiter 1D, the first and second inner passages 205a, 205b may be formed in the cylindrical portion 200D and the annular member 201D so as to open at the annular tapered surface 201a or 201b and extend in a direction intersecting (orthogonal to) the generatrix of the annular tapered surface 201a or 201b.

[0054] 6 is a cross-sectional view showing yet another torque limiter 1E of the present disclosure. Note that, among the components of the torque limiter 1E, the same elements as those of the torque limiter 1 described above are given the same reference numerals, and redundant explanations will be omitted.

[0055] As shown in FIG. 6, the torque limiter 1E includes a hollow outer transmission member 10E that is coaxially fixed to the inner circumferential surface of the rotor R, and a hollow inner transmission member 20E that is coaxially disposed inside the outer transmission member 10E and is coupled (fixed) to the input shaft IS so as to rotate integrally therewith. The outer transmission member 10E is a cylindrical body made of a metal such as steel, and includes an annular protrusion 101 that protrudes radially inward from the inner circumferential surface. The protrusion 101 is formed with a pair of annular tapered surfaces (first annular tapered surfaces) 101a, 101b that are inclined in opposite directions in the extension direction of the rotation axis of the outer transmission member 10E (rotor R) (see the dashed-dotted line in FIG. 6). The annular tapered surface 101a is an inverted conical surface (inverted tapered surface) whose diameter decreases from one end (left end in FIG. 6) to the other end (right end in FIG. 6) in the axial direction of the rotor R, with the rotation axis of the rotor R as its center axis. In addition, the annular tapered surface 101b is an inverted conical surface with the rotation axis of the rotor R, etc. as its central axis, which increases in diameter from one end (left end in Figure 6) of the rotor R in the axial direction to the other end (right end in Figure 6).

[0056] The pair of annular tapered surfaces 101a, 101b are formed symmetrically with respect to a plane that passes through the center of the protrusion 101 in the axial direction and is perpendicular to the rotation axis. That is, the axial length of the annular tapered surface 101a is the same as the axial length of the annular tapered surface 101b, and the apex angle of the cone that defines the annular tapered surface 101a is the same as the apex angle of the cone that defines the annular tapered surface 101b. Furthermore, two annular recesses 102a, 102b are formed in the outer transmission member 10E. The annular recess 102a extends along the outer periphery (outer periphery edge) 101o of the annular tapered surface 101a, and the annular recess 102b extends along the outer periphery 101o of the annular tapered surface 101b.

[0057] Furthermore, a first outer passage 115a and a second outer passage 115b are formed in the outer transmission member 10E. The first outer passage 115a is a through-hole (oil hole) that extends in the radial direction of the rotor R (cylindrical portion 110) and penetrates the outer transmission member 10E, communicates with the groove 117 on the outer peripheral surface of the outer transmission member 10E, and opens at the bottom surface of the annular recess 102a so as to correspond to the outer peripheral portion 101o of the annular tapered surface 101a. The second outer passage 115b is a through-hole (oil hole) that extends in the radial direction of the rotor R (cylindrical portion 110) and penetrates the outer transmission member 10E, opens at the outer peripheral surface of the outer transmission member 10E and communicates with the groove 117, and opens at the bottom surface of the annular recess 102b so as to correspond to the outer peripheral portion 101o of the annular tapered surface 101b. The first and second outer passages 115a, 115b may be formed in plurality in the outer transmission member 10E at intervals in the circumferential direction of the outer transmission member 10E, or each may be formed one by one in the outer transmission member 10E.

[0058] As shown in FIG. 6, the inner transmission member 20E includes a first transmission member (one-side transmission member) 21, a second transmission member 22 (the other-side transmission member), and a tightening mechanism 15E. The first transmission member 21 is a tubular body formed of a metal such as steel, and includes a substantially cylindrical tubular portion 210 and a reduced-diameter portion 211 formed at an end of the tubular portion 210 and having a smaller diameter than the tubular portion 210. A spline (not shown) is formed on the outer periphery of the end of the tubular portion 210 opposite the reduced-diameter portion 211, and the first transmission member 21 is configured to rotate integrally with (connected to or integrally formed with) the input shaft IS via the spline. In addition, a through-hole 211h extending in the axial direction is formed in the reduced-diameter portion 211. Furthermore, an annular tapered surface (second annular tapered surface) 212 is formed on the outer periphery of the end of the tubular portion 210 opposite the input shaft IS side (left side in FIG. 6).

[0059] The annular tapered surface 212 is a conical surface whose central axis is the rotation axis of the first transmission member 21 (see the dashed line in FIG. 6 ), and whose diameter increases from the end on the reduced diameter portion 211 side (the left side in FIG. 6 ) toward the end on the input shaft IS side (the right side in FIG. 6 ). The apex angle of the cone defining the annular tapered surface 212 is the same as the apex angle of the cone defining the annular tapered surface 101 a of the outer transmission member 10E. Furthermore, as shown in FIG. 6 , the axial length of the annular tapered surface 212 is longer than the axial length of the annular tapered surface 101 a of the outer transmission member 10E, and the area of ​​the annular tapered surface 212 is larger than the area of ​​the annular tapered surface 101 a.

[0060] Furthermore, in the torque limiter 1E, the hardness of the annular tapered surface 212 is made higher than the hardness of the annular tapered surface 101a by varying the heat treatment performed on the annular tapered surface 101a and the annular tapered surface 212, or by using a different material for the outer transmitting member 10E and the first transmitting member 21. In addition, a seal groove in which a seal member 118 such as a seal ring or an O-ring is disposed is formed on the outer peripheral surface of the cylindrical portion 210 of the first transmitting member 21 so as to be positioned closer to the input shaft IS than the annular tapered surface 212 (to the right in FIG. 6).

[0061] The second transmission member 22 is a tubular body made of metal such as steel, and includes, as shown in Fig. 6, a substantially cylindrical tubular portion 220 and an extending tubular portion 221 extending in the axial direction from the outer periphery of the end face of the tubular portion 220 on the side opposite to the input shaft IS side (the left side in Fig. 6). The tubular portion 220 of the second transmission member 22 has an inner diameter that is slightly larger than the outer diameter of the reduced diameter portion 211 of the first transmission member 21. The extending tubular portion 221 has an outer diameter that is the same as the outer diameter of the tubular portion 220, and an inner diameter that is larger than the inner diameter of the tubular portion 220.

[0062] Furthermore, an annular tapered surface (third annular tapered surface) 223 is formed on the outer peripheral surface of the end portion of the cylindrical portion 220 on the input shaft IS side (right side in FIG. 6). The annular tapered surface 223 is a conical surface whose central axis is the rotation axis of the second transmission member 22 (see the dashed line in FIG. 6) and whose diameter decreases from the end portion on the extended cylindrical portion 221 side (left side in FIG. 6) toward the end portion on the input shaft IS side (right side in FIG. 6). The apex angle of the cone defining the annular tapered surface 223 is the same as the apex angle of the cone defining the annular tapered surface 101b of the outer transmission member 10E. Furthermore, as shown in FIG. 6, the axial length of the annular tapered surface 223 is longer than the axial length of the annular tapered surface 101b of the outer transmission member 10E, and the area of ​​the annular tapered surface 223 is larger than the area of ​​the annular tapered surface 101b.

[0063] Furthermore, in the torque limiter 1E, the hardness of the annular tapered surface 223 is made higher than the hardness of the annular tapered surface 101b by varying the heat treatment performed on the annular tapered surface 101b and the annular tapered surface 223, or by using a different material for the outer transmission member 10E and the second transmission member 22. In addition, a seal groove in which a seal member 118 such as a seal ring or an O-ring is disposed is formed on the outer peripheral surface of the cylindrical portion 220 of the second transmission member 22 so as to be positioned closer to the extending cylindrical portion 221 side (left side in FIG. 6) than the annular tapered surface 223.

[0064] 6, the end of the first transmission member 21 on the reduced diameter portion 211 side is fitted (inserted) into the outer transmission member 10E so that the annular tapered surface 212 abuts against the annular tapered surface 101a of the protrusion 101 and the reduced diameter portion 211 is located radially inside the annular tapered surface 101b of the protrusion 101. Furthermore, the end of the second transmission member 22 on the annular tapered surface 223 side is inserted into the outer transmission member 10E so that the annular tapered surface 223 abuts against the annular tapered surface 101b of the protrusion 101. As a result, the outer transmission member 10E surrounds a portion of the first transmission member 21 and the second transmission member 22.

[0065] Furthermore, the reduced-diameter portion 211 of the first transmission member 21 is fitted (inserted) into the cylindrical portion 220 of the second transmission member 22, and the cylindrical portion 220 engages with a key (not shown) held by the reduced-diameter portion 211 as a rotation stopper. This restricts rotation of the second transmission member 22 relative to the first transmission member 21, and the second transmission member 22 is supported by the first transmission member 21 so as to rotate integrally therewith, and is coupled to the input shaft IS so as to rotate integrally therewith. However, the first transmission member 21 and the second transmission member 22 may be coupled to rotate integrally via a spline. The first and second transmission members 21 and 22 are then tightened by the tightening mechanism 15E so that the annular tapered surface 212 comes into close contact with the annular tapered surface 101a of the outer transmission member 10E, and the annular tapered surface 223 comes into close contact with the annular tapered surface 101b of the outer transmission member 10E. As a result, the pair of annular tapered surfaces 101a, 101b of the outer transmission member 10E and the annular tapered surfaces 212, 223 of the inner transmission member 20E form a frictional engagement portion that frictionally engages the outer transmission member 10E and the inner transmission member 20E inside the rotor R.

[0066] 6, the tightening mechanism 15E includes an annular disc spring 151 as an elastic member, an annular pressing member 152, a bolt 155, and a nut 157. The disc spring 151 is disposed within the extending cylindrical portion 221 of the second transmission member 22 so as to surround the tip of the reduced diameter portion 211 of the first transmission member 21 and abut against the end surface of the cylindrical portion 220 of the second transmission member 22. Furthermore, a pressing member 152 is disposed within the extending cylindrical portion 221 so as to abut against the disc spring 151. The tip of the reduced diameter portion 211 of the first transmission member 21 has a reduced diameter so as not to interfere with the disc spring 151, and the pressing member 152 abuts against the tip surface of the reduced diameter portion 211. That is, the disc spring 151 is disposed between the second transmission member 22 and the pressing member 152 so as to be located radially outside the abutting portion between the pressing member 152 and the reduced diameter portion 211 of the first transmission member 21.

[0067] The bolt 155 is inserted through the through hole 211h of the reduced diameter portion 211 via the inside of the cylindrical portion 210 of the first transmission member 21, and the head of the bolt 155 is pressed against the end surface of the reduced diameter portion 211 surrounding the through hole 211h on the input shaft IS side (the right side in FIG. 6) via a washer. The tip of the bolt 155 protrudes from the reduced diameter portion 211 and the pressing member 152 to the side opposite the input shaft IS side (the left side in FIG. 6). Furthermore, a washer is passed through the tip of the bolt 155 so as to abut against the pressing member 152, and a nut 157 is screwed onto it. As a result, the first and second transmission members 21 and 22 are tightened by the axial force of the bolt 155 via the disc spring 151 and the pressing member 152, and the second transmission member 22 is biased by the disc spring 151.

[0068] Furthermore, when the cylindrical portion 210 of the first transmission member 21 and the cylindrical portion 220 of the second transmission member 22 are fastened by the fastening mechanism 15E, an annular inner passage 205 is defined radially inside an inner circumferential portion (inner peripheral edge) 212i of the annular tapered surface 212 and an inner circumferential portion (inner circumferential edge) 223i of the annular tapered surface 223. As shown in FIG. 6 , the inner passage 205 communicates with the interior of the cylindrical portion 210 of the first transmission member 21 via at least one axial passage 207 formed in the first transmission member 21.

[0069] Furthermore, when the first transmission member 21 and the second transmission member 22 are fastened by the fastening mechanism 15E, the annular recess 102a of the outer transmission member 10E, the outer peripheral surface of the first transmission member 21 (the cylindrical portion 210), and a portion of the annular tapered surface 212 define an annular space for collecting wear debris. Furthermore, the seal member 118 disposed in the seal groove of the first transmission member 21 seals the gap between the outer transmission member 10E and the cylindrical portion 210 of the first transmission member 21 on the input shaft IS side (the right side in FIG. 6 ) of the annular space. Furthermore, the annular recess 102b of the outer transmission member 10E, the outer peripheral surface of the second transmission member 22 (the cylindrical portion 220), and a portion of the annular tapered surface 223 define an annular space for collecting wear debris. In addition, the seal member 118 arranged in the seal groove of the second transmission member 22 seals the gap between the outer transmission member 10E and the cylindrical portion 220 of the second transmission member 22 on the side opposite to the input shaft IS side of the annular space (the left side in Figure 6).

[0070] In this torque limiter 1E, oil as a lubricating / cooling medium guided into the hollow input shaft IS flows into the annular inner passage 205 through the inside of the first transmission member 21 (cylindrical portion 210) of the inner transmission member 20E and through axial passages 207 formed in the first transmission member 21. The oil that has flowed into the inner passage 205 is guided to the frictional engagement portions, i.e., the gap between the annular tapered surfaces 101a and 212 and the gap between the annular tapered surfaces 101b and 223, by centrifugal force generated in response to rotation of the rotor R, the outer transmission member 10E, and the inner transmission member 20E. This makes it possible for the oil supplied to the inner passage 205 to be well distributed throughout the gap between the annular tapered surfaces 101a and 212 and the gap between the annular tapered surfaces 101b and 223. Furthermore, the oil passes through the gaps between the annular tapered surfaces 101a and 212, the gaps between the annular tapered surfaces 101b and 223, and the multiple grooves formed in the annular tapered surfaces 101a and 101b, and is supplied to the rotor R by centrifugal force via the first and second outer passages 115a and 115b and groove 117 of the outer transmission member 10E.

[0071] As described above, in the torque limiter 1E, the lubrication path for supplying oil as a lubricating / cooling medium to the pair of annular tapered surfaces 101a, 101b and the annular tapered surfaces 212, 223 that form the frictional engagement portion is included midway in the lubrication path for supplying oil as a lubricating / cooling medium to the rotor R of the motor-generator MG. This eliminates the need for a dedicated lubrication structure for supplying oil to the pair of annular tapered surfaces 101a, 101b and the annular tapered surfaces 212, 223 in the torque limiter 1E. As a result, it is possible to stably lubricate and cool the torque limiter 1E while suppressing costs and improving space efficiency. Furthermore, stably lubricating the pair of annular tapered surfaces 101a, 101b and the annular tapered surfaces 212, 223 effectively suppresses variations in the static and dynamic friction coefficients between the annular tapered surfaces 101a and 212, and between the annular tapered surfaces 101b and 223, and the generation of wear debris. In addition, the outer transmission member 10E of the torque limiter 1E may include a substantially cylindrical tubular portion (tubular body) having at least one first outer passage 115a and at least one second outer passage 115b, and an annular member having a pair of annular tapered surfaces (first annular tapered surfaces) 101a, 101b and spline-engaged with the tubular portion so that the tubular portion rotates integrally.

[0072] 7 is a cross-sectional view showing another torque limiter 1F of the present disclosure. Note that, among the components of the torque limiter 1F, the same elements as those of the torque limiter 1 described above are given the same reference numerals, and redundant explanations will be omitted.

[0073] As shown in Fig. 7, the torque limiter 1F includes a hollow outer transmission member 10F coaxially fixed to the inner circumferential surface of the rotor R, a hollow inner transmission member 20F coaxially disposed inside the outer transmission member 10F and coupled (fixed) to the input shaft IS so as to rotate integrally therewith, and a friction engagement mechanism 30 having a multi-plate structure as a friction engagement part. The outer transmission member 10F is a tubular body formed from a metal such as steel, and includes a substantially cylindrical tubular portion 100 and an extending tubular portion 109 extending from the tubular portion 100. The extending tubular portion 109 extends in the axial direction from the outer periphery of the end face of the tubular portion 100 on the input shaft IS side (right side in Fig. 7), and has an inner diameter larger than the inner diameter of the tubular portion 100.

[0074] Furthermore, splines SP1 are formed on the inner peripheral surface of the extending cylindrical portion 109. Furthermore, a plurality of outflow passages 115 are formed (radially) at intervals in the circumferential direction in the extending cylindrical portion 109. Each outflow passage 115 opens at the tooth bottom of the splines SP1 of the extending cylindrical portion 109 and also opens on the outer peripheral surface of the extending cylindrical portion 109. Furthermore, a plurality of grooves (recesses) 117 that communicate with each outflow passage 115 and extend in the axial direction are formed on the outer peripheral surfaces of the cylindrical portion 100 and the extending cylindrical portion 109.

[0075] The inner transmission member 20F of the torque limiter 1F is a cylindrical body made of metal such as steel, and is connected to the input shaft IS via a spline (not shown) formed on one end (the right end in FIG. 2) of the inner transmission member 20F so as to rotate integrally therewith. A spline SP2 is formed on the outer peripheral surface of the other end (the left end in FIG. 2) of the inner transmission member 20F. Furthermore, a plurality of inner passages 205 are formed at intervals in the axial and circumferential directions on the other end of the inner transmission member 20F. Each inner passage 205 is a through-hole (oil hole) that extends radially of the inner transmission member 20F and penetrates the inner transmission member 20F, and opens at the inner peripheral surface of the inner transmission member 20F and at the tooth bottom of the spline SP2.

[0076] The friction engagement mechanism 30 includes a plurality of separator plates 31 (first friction engagement plates) and backing plates 32, a plurality of friction plates (second friction engagement plates) 33, and a fastening mechanism 15F that fastens these plates 31, 32, and 33. The separator plates 31 and the backing plates 32 are annular plates with smooth surfaces on both sides, and the outer peripheries of each are fitted into splines SP1 of the outer transmission member 10F. The friction plates 33 include an annular plate and friction materials attached to both sides of the plate, and the inner peripheries of each friction plate 33 are fitted into splines SP2 of the inner transmission member 20F so that the separator plates 31 and friction plates 33 are arranged alternately.

[0077] The tightening mechanism 15F includes an annular disc spring 151 as an elastic member, an annular pressing member 152, and a plurality of bolts 155. The disc spring 151 is disposed within the extending tubular portion 109 of the outer transmission member 10F so as to abut against the backing plate 32 of the friction engagement mechanism 30. The pressing member 152 is disposed so as to abut against the end face of the extending tubular portion 109 of the outer transmission member 10F and the disc spring 151. The plurality of bolts 155 are inserted into corresponding through holes formed in the pressing member 152 so that their heads abut against the pressing member 152, and are screwed into corresponding screw holes formed in the extending tubular portion 109 of the outer transmission member 10F. As a result, the plurality of separator plates 31 and the plurality of friction plates 33 are tightened by the axial force of the plurality of bolts 155 via the backing plate 32, the disc spring 151, and the pressing member 152. That is, the plurality of separator plates 31, the backing plates 32, the plurality of friction plates 33, and the tightening mechanism 15F form a friction engagement portion that frictionally engages the outer transmission member 10 and the inner transmission member 20 inside the rotor R.

[0078] In this torque limiter 1F, oil serving as a lubricating / cooling medium is guided into the hollow input shaft IS and flows into the inner transmission member 20F. The oil that has flowed into the inner transmission member 20F is guided through the multiple inner passages 205 to the gaps between the separator plates 31 and the friction plates 33, which serve as frictional engagement parts, by centrifugal force generated in response to rotation of the rotor R, outer transmission member 10E, and inner transmission member 20E. This allows the oil supplied to the inner transmission member 20F to be well distributed throughout the gaps between the separator plates 31 and the friction plates 33. The oil then passes through the gaps between the separator plates 31 and the friction plates 33 and is supplied to the rotor R by centrifugal force via the outflow passages 115 and grooves 117 of the outer transmission member 10E.

[0079] As described above, in the torque limiter 1F, the lubrication path for supplying oil as a lubricating / cooling medium to the separator plates 31, friction plates 33, etc., which form the friction engagement parts, is included midway in the lubrication path for supplying oil as a lubricating / cooling medium to the rotor R of the motor-generator MG. As a result, the torque limiter 1E also does not require a dedicated lubrication structure for supplying oil to the separator plates 31, friction plates 33, etc. As a result, it is possible to stably lubricate and cool the torque limiter 1E while suppressing costs and improving space efficiency. Furthermore, by stably lubricating the separator plates 31, friction plates 33, etc., it is possible to effectively suppress variations in the static and dynamic friction coefficients and the generation of wear powder between the separator plates 31, friction plates 33, etc.

[0080] Furthermore, in the torque limiter 1F, the pressing member 152 of the tightening mechanism 15F abuts against the axial end face of the rotor R on the input shaft IS side, restricting axial movement of the rotor R relative to the outer transmission member 10F (movement toward the input shaft IS side). This eliminates the need to provide a separate end plate that restricts axial movement of the rotor R relative to the outer transmission member 10F, making it possible to suppress an increase in the number of parts in the drive device including the motor generator MG and the torque limiter 1F.

[0081] In the torque limiters 1, 1B, 1C, 1D, 1E, and 1F, the disc spring 151 may be omitted from the tightening mechanism 15 and the like. Furthermore, in the torque limiters 1, 1B, 1C, 1D, 1E, and 1F, the outer transmission member 10, 10C, 10D, 10E, and 10F and the inner transmission member 20, 20B, 20C, 20D, 20E, and 20F may be formed of a material other than metal, such as resin, that enables frictional engagement between the two members. Furthermore, in the drive unit 5, the countershaft CS may be divided into two, and the torque limiters 1, 1B, 1C, 1D, 1E, and 1F may be disposed between the counter driven gear 62 and the drive pinion gear 63. In addition, a mechanical stepped or continuously variable transmission may be disposed between the input shaft IS of the drive unit 5 and the differential 65 instead of the gear train 6.

[0082] Furthermore, the torque limiters 1, 1B, 1C, 1D, 1E, and 1F may be applied to a hybrid vehicle including an engine (internal combustion engine), first and second electric motors, and a planetary gear (see, for example, Japanese Patent Application Laid-Open No. 2003-191760 and Japanese Patent No. 5252122). In this case, the torque limiters 1, 1B, 1C, 1D, 1E, and 1F may be disposed in at least one of the following locations: between the engine and the damper mechanism, between the engine and the damper mechanism and the planetary gear (carrier), between the first electric motor and the planetary gear (sun gear), between the counter drive gear and the counter driven gear, and between the second electric motor and the drive gear (counter driven gear).

[0083] Furthermore, the torque limiters 1, 1B, 1C, 1D, 1E, and 1F may be applied to a hybrid vehicle including an engine (internal combustion engine), an electric motor connected to the engine (crankshaft) directly or via a clutch, and a mechanical stepped or continuously variable transmission connected to the electric motor (rotor) directly or via a clutch. In this case, the torque limiters 1, 1B, 1C, 1D, 1E, and 1F may be disposed between the output member of the engine crankshaft or clutch and the input member of the transmission.

[0084] As described above, the torque limiter of the present disclosure is a torque limiter (1, 1B, 1C, 1D, 1E, 1F) that limits the torque transmitted between the drive side and the driven side to a predetermined limit torque (Tlim) or less, and includes a hollow outer transmission member (10, 10C, 10D, 10E, 10F) that is coaxially fixed to the inner circumferential surface of the rotor (R) of the electric motor (MG), and the outer transmission member ( a hollow inner transmission member (20, 20B, 20C, 20D, 20E, 20F) disposed coaxially inside the rotor (R); and frictional engagement portions (201a, 201b, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 200, 123, 101a, 101b, 212, 223, 31, 33), and formed on the inner transmission member (20, 20B, 20C, 20D, 20E, 20F) so as to guide the lubricating medium supplied inside the inner transmission member (20, 20B, 20C, 20D, 20E, 20F) to the friction engagement portions (201a, 201b, 112, 123, 101a, 101b, 212, 223, 31, 33). and outer passages (105, 115, 115a, 115b) formed in the outer transmission member (10, 10C, 10D, 10E, 10F) so as to guide the lubricating medium that has passed through the friction engagement portions (201a, 201b, 112, 123, 101a, 101b, 212, 223, 31, 33) to the rotor (R).

[0085] The torque limiter disclosed herein includes a hollow outer transmission member coaxially fixed to the inner circumferential surface of the rotor of an electric motor, a hollow inner transmission member coaxially disposed within the outer transmission member, and a frictional engagement portion that frictionally engages the outer transmission member and the inner transmission member within the rotor. A lubricant is supplied to the inner transmission member and guided to the frictional engagement portion within the rotor through an inner passage formed in the inner transmission member. Furthermore, the lubricant that passes through the frictional engagement portion is guided to the rotor through an outer passage formed in the outer transmission member. As a result, the lubrication path for supplying the lubricant to the frictional engagement portion is included in the lubrication path for supplying the lubricant to the rotor of the electric motor, eliminating the need for a dedicated lubrication structure for supplying the lubricant to the frictional engagement portion. This enables stable lubrication of the torque limiter while suppressing cost increases and improving space efficiency. Furthermore, stable lubrication of the torque limiter, i.e., the frictional engagement portion, effectively suppresses variations in the static and dynamic friction coefficients and the generation of wear debris in the frictional engagement portion.

[0086] In addition, one of the outer transmission member (10, 10C, 10D, 10E) and the inner transmission member (20, 20B, 20C, 20D, 20E) may include a pair of first annular tapered surfaces (201a, 201b, 101a, 101b) inclined in opposite directions to each other in the axial direction of the rotor (R), and The other of the transmission members (20, 20B, 20C, 20D, 20E) includes a one-side transmission member (11, 11C, 11D, 21) having a second annular tapered surface (112, 212) that can abut against one of the pair of first annular tapered surfaces (201a, 201b, 101a, 101b), and a third annular tapered surface (112, 212) that can abut against the other of the pair of first annular tapered surfaces (201a, 201b, 101a, 101b). the second annular tapered surface (112, 212) abuts against one of the pair of first annular tapered surfaces (201a, 201b, 101a, 101b), and the third annular tapered surface (123, 223) abuts against the other of the pair of first annular tapered surfaces (201a, 201b, 101a, 101b). The transmission mechanism may include a tightening mechanism (15, 15E) that tightens the one-side transmission member (11, 11C, 11D, 21) and the other-side transmission member (12, 12D, 22) in the axial direction, and the frictional engagement portion may be formed by the first, second and third annular tapered surfaces (201a, 201b, 112, 123, 101a, 101b, 212, 223).

[0087] In this torque limiter, it is possible to ensure a sufficient contact area between the pair of first annular tapered surfaces and the second and third annular tapered surfaces while suppressing an increase in the outer diameters of the outer and inner transmission members. Therefore, by applying a sufficient tightening force to the one-side transmission member and the other-side transmission member, it is possible to ensure a sufficient limit torque, which is the upper limit of torque that does not cause slippage between the pair of first annular tapered surfaces and the second and third annular tapered surfaces. Furthermore, by applying the above-mentioned lubrication structure including the inner and outer passages to this torque limiter, it is possible to suppress an increase in cost, improve space efficiency, and stably and sufficiently ensure the limit torque.

[0088] Furthermore, the friction engagement portion may include a first friction engagement plate (31, 32) fitted to one of the outer transmission member (10F) and the inner transmission member (20F), a second friction engagement plate (33) fitted to the other of the outer transmission member (10F) and the inner transmission member (20F), and a tightening mechanism (15F) that tightens the first and second friction engagement plates (31, 32, 33).

[0089] That is, the friction engagement portion of the torque limiter of the present disclosure may have a so-called multi-plate structure.

[0090] Furthermore, the pair of first annular tapered surfaces (201a, 201b) may be conical surfaces formed on the inner transmission member (20, 20D) so as to be inclined in opposite directions to each other, and the second and third annular tapered surfaces (112, 123) may be inverted conical surfaces formed on the one side transmission member (11, 11D) or the other side transmission member (12, 12D) of the outer transmission member (10, 10D), and the inner passage may include a first inner passage (205a) that guides the lubricating medium to the inner peripheral portion (201i) of one of the first annular tapered surfaces (201a) and a second inner passage (205b) that guides the lubricating medium to the inner peripheral portion (201i) of the other first annular tapered surface (201b).

[0091] This allows the centrifugal force generated in response to the rotation of the rotor, the outer transmission member, and the inner transmission member to ensure that the lubricating medium supplied to the first and second inner passages is distributed effectively throughout the gap between one side of the first annular tapered surface and the second annular tapered surface, and the gap between the other side of the first annular tapered surface and the third annular tapered surface.

[0092] Furthermore, the pair of first annular tapered surfaces (201a, 201b) may be conical surfaces formed on the inner transmission member (20C) so as to be inclined in opposite directions to each other, the second and third annular tapered surfaces (112, 123) may be inverted conical surfaces formed on the one side transmission member (11C) or the other side transmission member (12) of the outer transmission member (10C), and the inner passage may include a first inner passage (205a) opening at one side (201a) of the first annular tapered surfaces and a second inner passage (205b) opening at the other side (201b) of the first annular tapered surfaces.

[0093] In such a torque limiter, the lubricating medium supplied to the first and second inner passages can be effectively distributed to the gap between one side of the first annular tapered surface and the second annular tapered surface, and the gap between the other side of the first annular tapered surface and the third annular tapered surface.

[0094] The outer passage may also include an annular passage (105) defined by the one-side transmission member (11, 11C, 11D) and the other-side transmission member (12, 12D) radially outward from the outer circumferential portion (112o) of the second annular tapered surface (112) and the outer circumferential portion (123o) of the third annular tapered surface (123), and an outflow passage (115) formed in either the one-side transmission member (11, 11C, 11D) or the other-side transmission member (12, 12D) so as to communicate with the annular passage (105) and extend radially of the rotor (R).

[0095] This allows the lubricating medium that flows out from the frictional engagement portion, i.e., the gap between one side of the first annular tapered surface and the second annular tapered surface and the gap between the other side of the first annular tapered surface and the third annular tapered surface, to be collected in the annular passage and supplied to the rotor via the outflow passage by centrifugal force.

[0096] Furthermore, the inner passages (205a, 205b) may extend in the radial direction of the rotor (R).

[0097] This allows the lubricating medium supplied to the inside of the inner transmission member to be smoothly supplied through the gap between one side of the first annular tapered surface and the second annular tapered surface, and the gap between the other side of the first annular tapered surface and the third annular tapered surface.

[0098] Furthermore, the first and second inner passages (205a, 205b) may extend in a direction intersecting the one or the other of the first annular tapered surfaces (201a, 201b), respectively.

[0099] This makes it possible to further improve the workability when forming the first and second inner passages in the inner transmission member.

[0100] Furthermore, the outer passage may include a passage (115C) that opens at the second or third annular tapered surface (201a) so as to face the opening end of the first or second inner passage (205a) and extends in a direction intersecting the second or third annular tapered surface (201a).

[0101] This makes it possible to increase the amount of lubricant supplied to the rotor.

[0102] Furthermore, one of the outer transmission member and the inner transmission member (20D, 10E) may include a cylindrical body (200D) and an annular member (201D) having the pair of first annular tapered surfaces (201a, 201b, 101a, 101b) and spline-engaged with the cylindrical body (200D) so that the cylindrical body (200D) rotates integrally.

[0103] This makes it possible to further improve the ease of assembly of the torque limiter.

[0104] Furthermore, the pair of first annular tapered surfaces (101a, 101b) may be inverted conical surfaces formed on the outer transmission member (10E) so as to be inclined in opposite directions to each other, and the second and third annular tapered surfaces (212, 223) may be conical surfaces formed on the one-side transmission member or the other-side transmission member (21, 22) of the inner transmission member (20E), and the one-side transmission member (21) and the other-side transmission member (22) are connected to the second annular tapered surfaces (212, 223). The annular inner passage (205) may be defined radially inward of the inner peripheral portion (212i, 223i) of the first annular tapered surface (212) and the third annular tapered surface (223), and the outer passage may include a first outer passage (115a) corresponding to the outer peripheral portion (101o) of one (101a) of the pair of first annular tapered surfaces and a second outer passage (115b) corresponding to the outer peripheral portion (101o) of the other (101b) of the pair of first annular tapered surfaces.

[0105] In this torque limiter, centrifugal force generated in response to rotation of the rotor, outer transmission member, and inner transmission member can effectively distribute the lubricating medium supplied to the annular inner passage through the gap between one side of the first annular tapered surface and the second annular tapered surface and the gap between the other side of the first annular tapered surface and the third annular tapered surface. Furthermore, the lubricating medium flowing out from the gap between one side of the first annular tapered surface and the second annular tapered surface can be supplied to the rotor via the first outer passage by centrifugal force, and the lubricating medium flowing out from the gap between the other side of the first annular tapered surface and the third annular tapered surface can be supplied to the rotor via the second outer passage by centrifugal force.

[0106] The tightening mechanism (15, 15F) may restrict movement of the rotor (R) in the axial direction relative to the outer transmission member (10, 10C, 10D, 10F).

[0107] This eliminates the need for a separate member to restrict the axial movement of the rotor relative to the outer transmission member, making it possible to suppress an increase in the number of parts in the drive device including the electric motor and torque limiter.

[0108] It should be noted that the invention of the present disclosure is not limited to the above-described embodiment, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely one specific form of the invention described in the Summary of the Invention section, and does not limit the elements of the invention described in the Summary of the Invention section. [Industrial Applicability]

[0109] The invention of the present disclosure can be used in the torque limiter manufacturing industry and the like. [Explanation of symbols]

[0110] 1, 1B, 1C, 1D, 1E, 1F Torque limiter, 5 Drive device, 6 Gear train, 7 Case, 10, 10C, 10D, 10E, 10F Outer transmission member, 100 Cylindrical portion, 101 Protrusion portion, 101a Annular tapered surface, 101b Annular tapered surface, 101o Outer peripheral portion, 102a, 102b Annular recessed portion, 105 Annular passage (outer passage), 109 Extended cylindrical portion, 11, 11C, 11D First transmission member, 110 Cylindrical portion, 111 Extended cylindrical portion, 112 Annular tapered surface, 112o Outer peripheral portion, 114 Annular recessed portion, 115, 115C Outlet passage (outer passage), 115a First outer passage, 115b Second outer passage, 117 Groove, 118 Seal member, 12, 12D Second transmission member, 120 Cylindrical portion, 121 Extended cylindrical portion, 123 Annular tapered surface, 123o Outer periphery, 124 Annular recess, 14 Key, 15, 15E, 15F Tightening mechanism, 151 Disc spring, 152 Pressing member, 155 Bolt, 157 Nut, 20, 20B, 20C, 20D, 20E, 20F Inner transmission member, 200, 200D Cylindrical portion, 201 Protrusion, 201D Annular member, 201a, 201b Annular tapered surface, 201i, 212i, 223i Inner periphery, 202a, 202b Annular recess, 205 Inner passage, 205a First inner passage, 205b Second inner passage, 207 Axial passage, 21 First transmission member, 210 cylindrical portion, 211 reduced diameter portion, 211h through hole, 212 annular tapered surface, 22 second transmission member, 220 cylindrical portion, 221 extended cylindrical portion, 223 annular tapered surface, 30 friction engagement mechanism, 31 separator plate, 32 backing plate, 33 friction plate, 61 counter drive gear, 62 counter driven gear, 63 drive pinion gear, 64 differential ring gear, 65 differential gear, CS counter shaft, IS input shaft, DS drive shaft, DW drive wheel, MG motor generator, R rotor, S stator, SP1, SP2 splines, V vehicle.

Claims

1. A torque limiter that limits torque transmitted between a driving side and a driven side to a predetermined limit torque or less, a hollow outer transmission member coaxially fixed to the inner circumferential surface of the rotor of the electric motor; a hollow inner transmission member disposed coaxially inside the outer transmission member; a friction engagement portion that frictionally engages the outer transmission member and the inner transmission member inside the rotor; an inner passage formed in the inner transmission member to guide a lubricating medium supplied to the inside of the inner transmission member to the friction engagement portion; an outer passage formed in the outer transmission member so as to guide the lubricating medium that has passed through the frictional engagement portion toward the rotor; Equipped with one of the outer transmission member and the inner transmission member includes a pair of first annular tapered surfaces inclined in opposite directions to each other in the axial direction of the rotor, the other of the outer transmission member and the inner transmission member includes a one-side transmission member having a second annular tapered surface abuttable against one of the pair of first annular tapered surfaces, an other-side transmission member having a third annular tapered surface abuttable against the other of the pair of first annular tapered surfaces, and a tightening mechanism that tightens the one-side transmission member and the other-side transmission member in the axial direction so that the second annular tapered surface abuts against the one of the pair of first annular tapered surfaces and the third annular tapered surface abuts against the other of the pair of first annular tapered surfaces, the frictional engagement portion is formed by the first, second, and third annular tapered surfaces, the pair of first annular tapered surfaces are conical surfaces formed on the inner transmission member so as to be inclined in opposite directions to each other, the second and third annular tapered surfaces are inverted conical surfaces formed on the one transmission member or the other transmission member of the outer transmission member, The torque limiter includes a first inner passage that guides the lubricating medium to one of the inner circumferential portions of the first annular tapered surface, and a second inner passage that guides the lubricating medium to the other inner circumferential portion of the first annular tapered surface.

2. A torque limiter that limits the torque transmitted between a drive side and a driven side to a predetermined limit torque or less, a hollow outer transmission member coaxially fixed to the inner circumferential surface of the rotor of the electric motor; a hollow inner transmission member disposed coaxially inside the outer transmission member; a friction engagement portion that frictionally engages the outer transmission member and the inner transmission member inside the rotor; an inner passage formed in the inner transmission member to guide a lubricating medium supplied to the inside of the inner transmission member to the friction engagement portion; an outer passage formed in the outer transmission member so as to guide the lubricating medium that has passed through the frictional engagement portion toward the rotor; Equipped with one of the outer transmission member and the inner transmission member includes a pair of first annular tapered surfaces inclined in opposite directions to each other in the axial direction of the rotor, the other of the outer transmission member and the inner transmission member includes a one-side transmission member having a second annular tapered surface abuttable against one of the pair of first annular tapered surfaces, an other-side transmission member having a third annular tapered surface abuttable against the other of the pair of first annular tapered surfaces, and a tightening mechanism that tightens the one-side transmission member and the other-side transmission member in the axial direction so that the second annular tapered surface abuts against the one of the pair of first annular tapered surfaces and the third annular tapered surface abuts against the other of the pair of first annular tapered surfaces, the frictional engagement portion is formed by the first, second, and third annular tapered surfaces, the pair of first annular tapered surfaces are conical surfaces formed on the inner transmission member so as to be inclined in opposite directions to each other, the second and third annular tapered surfaces are inverted conical surfaces formed on the one transmission member or the other transmission member of the outer transmission member, The torque limiter includes a first inner passage that opens onto the one side of the first annular tapered surface, and a second inner passage that opens onto the other side of the first annular tapered surface.

3. 3. The torque limiter according to claim 1, The outer passage of the torque limiter includes: an annular passage defined by the one-side transmission member and the other-side transmission member radially outward from the outer periphery of the second annular tapered surface and the outer periphery of the third annular tapered surface; and an outflow passage formed in either the one-side transmission member or the other-side transmission member so as to communicate with the annular passage and extend in the radial direction of the rotor.

4. 3. The torque limiter according to claim 1, The inner passage is a torque limiter extending radially of the rotor.

5. 3. The torque limiter according to claim 2, The first and second inner passages extend in a direction intersecting the one or the other of the first annular tapered surfaces, respectively.

6. The torque limiter according to claim 5, a torque limiter including a passage that opens at the second or third annular tapered surface so as to face an opening end of the first or second inner passage and extends in a direction intersecting the second or third annular tapered surface.

7. 3. The torque limiter according to claim 1, A torque limiter in which one of the outer transmission member and the inner transmission member includes a cylindrical body and an annular member having the pair of first annular tapered surfaces and splined to the cylindrical body so as to rotate integrally.

8. A torque limiter that limits the torque transmitted between a drive side and a driven side to a predetermined limit torque or less, a hollow outer transmission member coaxially fixed to the inner circumferential surface of the rotor of the electric motor; a hollow inner transmission member disposed coaxially inside the outer transmission member; a friction engagement portion that frictionally engages the outer transmission member and the inner transmission member inside the rotor; an inner passage formed in the inner transmission member to guide a lubricating medium supplied to the inside of the inner transmission member to the friction engagement portion; an outer passage formed in the outer transmission member so as to guide the lubricating medium that has passed through the frictional engagement portion toward the rotor; Equipped with one of the outer transmission member and the inner transmission member includes a pair of first annular tapered surfaces inclined in opposite directions to each other in the axial direction of the rotor, the other of the outer transmission member and the inner transmission member includes a one-side transmission member having a second annular tapered surface abuttable against one of the pair of first annular tapered surfaces, an other-side transmission member having a third annular tapered surface abuttable against the other of the pair of first annular tapered surfaces, and a tightening mechanism that tightens the one-side transmission member and the other-side transmission member in the axial direction so that the second annular tapered surface abuts against the one of the pair of first annular tapered surfaces and the third annular tapered surface abuts against the other of the pair of first annular tapered surfaces, the frictional engagement portion is formed by the first, second, and third annular tapered surfaces, the pair of first annular tapered surfaces are inverted conical surfaces formed on the outer transmission member so as to be inclined in opposite directions to each other, the second and third annular tapered surfaces are conical surfaces formed on the one transmission member or the other transmission member of the inner transmission member, the one-side transmission member and the other-side transmission member define an annular inner passage radially inward of inner circumferential portions of the second annular tapered surface and the third annular tapered surface, The torque limiter includes a first outer passage corresponding to an outer periphery of one of the pair of first annular tapered surfaces, and a second outer passage corresponding to an outer periphery of the other of the pair of first annular tapered surfaces.

9. 3. The torque limiter according to claim 1, The tightening mechanism is a torque limiter that restricts movement of the rotor relative to the outer transmission member in the axial direction.

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