Power transmission device

Abstract

To make a power transmission device compact and less in electric power consumption.SOLUTION: In an excitation type power transmission device, a first clutch 10 and an electromagnetic type second clutch 20 which switch an outer ring 12 and an inner ring 11 between an engagement state and an engagement-released state are combined to attract an armature 22 to a field core 25 by energization to the second clutch 20, the first clutch 10 is engaged by frictional resistance of contact surfaces of the armature 22 and the field core 25, and disengagement of the first clutch 10 is controlled by non-energization to the second clutch 20. The power transmission device is provided with a gap w between an inner diameter of the field core 25 and an outer diameter of a shaft part 1 provided on the inner ring 11, and arranges a frictional lock material 40 in the gap w to control the rotation of the inner ring 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power transmission device in which the power of a rotationally driven input member is transmitted to a stationary member, thereby enabling the input member to be stopped at any desired timing. [Background technology]

[0002] A known power transmission device in which a rotationally driven input member can be stopped at any time uses a combination of an engagement type clutch and an electromagnetic clutch to switch between transmitting and cutting off power from the input member to a stationary member.

[0003] For example, the power transmission device disclosed in Patent Document 1, as shown in FIG. 5, comprises a shaft 51 as an input member, a case 52 as a stationary member that is stationary relative to the shaft 51, an engagement type clutch 60 provided between the shaft 51 and the case 52, and an electromagnetic clutch 70 that switches the engagement type clutch 60 between an engaged state and a disengaged state.

[0004] The engagement type clutch 60 is assembled between an inner ring 61 formed integrally with the shaft 51 and an outer ring 62 fixed to the case 52, with a plurality of rollers 63 as engagement elements held by a cage 64. The electromagnetic clutch 70 has an armature 72 that engages with the cage 64 of the engagement type clutch 60 in the circumferential direction via an intermediate plate 71, an electromagnet 73 that faces the armature 72 with a specified gap in the axial direction, and a separation spring 74 that urges the armature 72 in a direction away from the electromagnet 73.

[0005] The electromagnet 73 of the electromagnetic clutch 70 is formed by winding a solenoid coil 76 around an annular field core 75. The separation spring 74 is disposed such that one end of the separation spring 74 abuts against the surface of the field core 75 facing the armature 72, and the other end of the separation spring 74 is accommodated in an annular recess 72a formed in the surface of the armature 72 facing the field core 75.

[0006] When the electromagnet 73 is energized, the armature 72 is attracted to the field core 75, and the engagement type clutch 60 is engaged when power (rotational torque) is applied to the shaft 51, and power is transmitted from the shaft 51 to the case 52 via the engagement type clutch 60, stopping the rotation of the shaft 51. On the other hand, when the electromagnet 73 is not energized, the armature 72 moves away from the electromagnet 73, the engagement type clutch 60 is disengaged, the transmission of power from the shaft 51 to the case 52 is cut off, and the shaft 51 is allowed to rotate freely. In other words, this power transmission device is an excitation type that operates (transmits power) when current is applied to the electromagnetic clutch 70.

[0007] Patent document 2 discloses a non-excitation type power transmission device in which the transmission of power from shaft 51 to case 52 is cut off when current is applied to electromagnetic clutch 70, and which operates (transmits power) when current is removed from electromagnetic clutch 70. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2023-045468 A [Patent Document 1] JP 2023-055395 A Summary of the Invention [Problem to be solved by the invention]

[0009] Incidentally, the power transmission devices of Patent Documents 1 and 2 have a structure in which the engagement type clutch 60 fixes the rotation of the outer ring 62 and rotates the shaft 51. For this reason, when the input shaft 51 rotates at a high angular acceleration, it is necessary to increase the spring force (torque) of the centering spring 77 so that the inertial force (torque) acting on the cage 64, rollers 63, etc. does not exceed the biasing force of the centering spring 77. In this case, an electromagnet 73 that generates an attractive force (torque) stronger than this spring force (torque) is required, which causes problems such as an increase in the size of the device and an increase in current consumption.

[0010] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to reduce the size and power consumption of a power transmission device. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides a clutch mechanism comprising: an input side member that is rotationally driven; a stationary member that is stationary with respect to the input side member; a first clutch that is disposed between an inner ring fixed to the stationary member and an outer ring fixed to the input side member; and an electromagnetic second clutch that switches the first clutch between an engaged state and a disengaged state, the second clutch has an armature, an electromagnet having a solenoid coil wound around an annular field core facing the armature with a predetermined gap in the axial direction, and a separation spring that urges the armature in a direction away from the electromagnet, and when current is applied to the electromagnet, the armature is attracted to the field core, thereby bringing the first clutch into an engaged state, and when current is not applied to the electromagnet, the armature is separated from the electromagnet, thereby bringing the first clutch into a disengaged state; A gap is provided between the inner diameter of the field core and the outer diameter of the shaft portion provided on the inner ring, and a friction locking material is disposed in the gap to regulate the rotation of the inner ring, thereby forming a power transmission device (Configuration 1).

[0012] In order to solve the above problems, the present invention provides a clutch mechanism comprising: an input side member that is driven to rotate; a stationary member that is stationary relative to the input side member; a first clutch that is disposed between an inner ring that is fixed to the stationary member and an outer ring that is fixed to the input side member; and an electromagnetic second clutch that switches the first clutch between an engaged state and a disengaged state, The second clutch has an armature, an electromagnet having a solenoid coil wound around an annular field core facing the armature with a predetermined gap in the axial direction, and a separation spring that urges the armature in a direction away from the electromagnet, and when current is applied to the electromagnet, the armature is attracted to the field core, thereby disengaging the first clutch, and when current is not applied to the electromagnet, the armature is separated from the electromagnet, thereby engaging the first clutch, A gap is provided between the inner diameter of the field core and the outer diameter of the shaft portion provided on the inner ring, and a friction locking material is disposed in the gap to regulate the rotation of the inner ring, thereby forming a power transmission device (Configuration 2).

[0013] In an embodiment having configuration 1 or configuration 2, the first clutch can be incorporated with an engaging element held between the outer ring and the inner ring by a retainer, the retainer engaging with the armature in the circumferential direction, and the retainer moving the engaging element circumferentially relative to the inner ring and the outer ring, thereby switching between an engaged state in which the engaging element engages with the inner ring and the outer ring and a disengaged state in which the engaging element does not engage with the inner ring and the outer ring (configuration 3).

[0014] In an embodiment having configuration 1 or 2, or in an embodiment adding configuration 3 to either of them, a configuration can be adopted in which the electromagnet is provided with a flange separate from or integral with the field core, and the flange and the stationary member are fixed to regulate the rotation of the electromagnet (configuration 4).

[0015] In addition, in an embodiment having configuration 4, a configuration can be adopted in which the gap between the flange and the stationary member is sealed with a sealant (configuration 5).

[0016] In addition, in an embodiment having configuration 1 or 2, or in an embodiment having one or more configurations selected from configurations 3 to 5 added thereto, the friction locking material can be a ring-shaped member that applies a spring load to the inner diameter of the field core and the outer diameter of the shaft portion along the radial direction of the bearing (configuration 6).

[0017] In the embodiment having the configuration 1 or 2, or in the embodiment having one or more configurations selected from the configurations 3 to 6 added thereto, it is further preferable that the friction locking material is made of a non-magnetic material (configuration 7). Effect of the Invention

[0018] According to the present invention, the power transmission device can be made smaller and consume less power. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a vertical cross-sectional view of a power transmission device according to a first embodiment of the present invention. [Diagram 2] Cross-sectional view taken along line II-II in Figure 1. [Diagram 3] FIG. 11 is a vertical cross-sectional view of a power transmission device according to a second embodiment of the present invention. [Figure 4] FIG. 11 is a vertical cross-sectional view showing a modified example of the second embodiment. [Diagram 5] FIG. 1 is a vertical cross-sectional view of a conventional power transmission device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figures 1 and 2 show an excitation type power transmission device according to a first embodiment of the present invention. The basic configuration and operation of the power transmission device of the embodiment are the same as the conventional example shown in Figure 5 above, and the configuration and operation will be described in detail below, along with the differences from the conventional one.

[0021] 1, the power transmission device includes an engagement type first clutch 10 provided between an input side member that is rotationally driven and a stationary member that is stationary relative to the input side member. Hereinafter, in the embodiment, the first clutch 10 will be referred to as an engagement type clutch 10.

[0022] The engagement type clutch 10 includes a plurality of engagement elements 13 between an inner ring 11 fixed to a stationary member and an outer ring 12 fixed to an input side member, and is assembled in a state in which the plurality of engagement elements 13 are held in the circumferential direction by a retainer 14. The engagement type clutch 10 is configured to be switched between an engaged state in which the engagement elements 13 engage with the inner ring 11 and the outer ring 12 and a disengaged state in which the engagement elements 13 do not engage with the inner ring 11 and the outer ring 12 by the retainer 14 moving the engagement elements 13 relative to the inner ring 11 and the outer ring 12 in the circumferential direction. The switching between the engaged state and the disengaged state of the engagement type clutch 10 is controlled by an electromagnetic second clutch 20. In the following embodiments, the second clutch 20 is referred to as the electromagnetic clutch 20.

[0023] Here, instead of the conventional outer ring fixed / inner ring rotating type clutch 60 (see FIG. 5), an inner ring fixed / outer ring rotating type clutch 10 is adopted. A cylindrical case 2 that houses the clutch 10 and the electromagnetic clutch 20 is fixed to a housing (not shown) or the like to form a stationary member. The inner ring 11 has a shaft portion 1 that protrudes in the axial direction at one axial end side (the right side in FIG. 1, hereinafter simply referred to as the one end side), and the shaft portion 1 is fixed to the case 2 via an electromagnet 23 provided in the electromagnetic clutch 20, so that the shaft portion 1 is immovable relative to the case 2, which is a stationary member. An input side member (not shown) is coupled by a spline or the like to a connection hole that opens into an end face of a shaft portion 12d provided at the other axial end side (the left side in FIG. 1, hereinafter simply referred to as the other end side) of the outer ring 12, and the input side member and the outer ring 12 rotate around the axis together.

[0024] A bearing 30 that rotatably supports the case 2 and the outer ring 12 is disposed between the inner periphery of the case 2 and the outer periphery of the outer ring 12. In addition, a bearing 31 that rotatably supports the inner ring 11 and the outer ring 12 is disposed between the outer periphery of the other end side of the inner ring 11 and the inner periphery of the outer ring 12.

[0025] The multiple engagement elements 13 of the engagement element type clutch 10 are held in the circumferential direction by a cage 14, and a centering spring 15 is engaged with the outer ring 12 and the cage 14 in a non-rotating state. In the embodiment, rollers are used as the engagement elements 13, and therefore, hereinafter, the engagement elements 13 will be referred to as rollers 13.

[0026] 2, a plurality of cam surfaces 12a are formed along the circumferential direction on the inner peripheral surface 12b of the outer ring 12, and each cam surface 12a faces radially the cylindrical surface of the outer peripheral surface 11a of the inner ring 11. As a result, a wedge-shaped space 18 that gradually narrows from the circumferential center toward both ends is formed between each cam surface 12a and the cylindrical surface of the outer peripheral surface 11a of the inner ring 11, and one roller 13 is disposed in each wedge-shaped space 18.

[0027] The cage 14 is an annular member with a number of pockets 14a arranged along the circumferential direction. Each pocket 14a accommodates one roller 13. The cage 14 is assembled to the outer ring 12 so that its axial movement is restricted and it is supported so as to be movable in the circumferential direction. The engagement type clutch 10 is switched between a disengaged state and an engaged state by changing the relative position of the rollers 13 held by the cage 14 with respect to the wedge-shaped space 18.

[0028] As shown in Fig. 2, the centering spring 15 is composed of a C-shaped annular portion 15a and a pair of hooks 15b protruding in the outer radial direction, the C-shaped annular portion 15a is fitted into an annular groove 14b formed on the inner circumference of the axial center portion of the cage 14, and the pair of hooks 15b is fitted into a cage groove 14c penetrating the cage 14 in the radial direction and a radial groove 12c formed on one axial end face of the outer ring 12. The cage groove 14c and the radial groove 12c of the outer ring 12 are formed to have the same circumferential width, and the hooks 15b are in contact with the inner groove surfaces at both circumferential ends of the cage groove 14c and the inner groove surfaces at both circumferential ends of the radial groove 12c of the outer ring 12, respectively. As a result, the centering spring 15 is prevented from rotating by the outer ring 12, and the cage 14 is elastically held in a position where the rollers 13 do not engage with the inner ring 11 and the outer ring 12.

[0029] The electromagnetic clutch 20 comprises a disk-shaped armature 22 fitted onto the outer periphery of the shaft portion 1 at one end of the engagement type clutch 10, an electromagnet 23 facing the armature 22 at one end with a specified gap therebetween, and a separation spring 24 that biases the armature 22 in a direction away from the electromagnet 23. The armature 22 is composed of a plate-like member made of a magnetic material (iron, silicon steel, etc.), and is fitted onto the outer periphery of the shaft portion 1 in a state in which it can rotate freely and move axially.

[0030] The electromagnet 23 has an annular field core 25 with a C-shaped cross section that opens axially toward the armature 22, and a solenoid coil 27 wound around the field core 25, and is fixed inside the case 2. The solenoid coil 27 is adapted to receive power from the outside through a lead wire 28 that passes through a through hole formed at one end of the case 2.

[0031] The recoil spring 24 is made of an annular elastic member such as a wave washer, and one end of the spring is accommodated in an annular recess 26 formed on the surface of the field core 25 facing the armature 22, and the other end of the spring is disposed in contact with the surface of the armature 22 facing the electromagnet 23.

[0032] The opening of one end of the case 2 is closed by a flange 5 (referred to as a lid 5 in the embodiment) fixed to a field core 25 of the electromagnet 23. The field core 25 and the lid 5 can be fixed by, for example, welding. The lid 5 has a through hole 5a through which a lead wire 28 of the electromagnet 23 passes, and a grommet 29 is attached between the through hole 5a of the lid 5 and the through hole of the case 2 and the lead wire 28 inserted therethrough. The lid 5 is fixed to a flange portion 4 provided at an end portion on one end side of the case 2 by a screw 7. The screw 7 is screwed into a through hole provided in the lid 5 and a screw hole 4a formed in the flange portion 4. The gap between the end face of the flange portion 4 and the end face of the lid 5 is liquid-tightly sealed by a seal material 6.

[0033] In the electromagnetic clutch 20, an engaging protrusion 14d formed on one end of the cage 14 is inserted into an axial hole 22a formed in the armature 22 so as to penetrate the armature 22 from front to back without any gap in the circumferential direction, thereby directly engaging the armature 22 with the cage 14 in the circumferential direction. In addition, a field core 25 of the electromagnet 23 is fixed to the shaft 1 via a friction locking member 40 described later, so that the shaft 1 and the inner ring 11 are stationary with respect to the outer ring 12.

[0034] In this electromagnetic clutch 20, when the electromagnet 23 is not energized and in a non-excited state, the biasing force of the separation spring 24 supports the armature 22 at a position axially spaced from the electromagnet 23, thereby enabling the armature 22 to rotate, and the cage 14 engaged with the armature 22 in the circumferential direction also becomes rotatable. For this reason, when in a non-excited state, even if the outer ring 12, which is the input side, rotates, the engagement type clutch 10 maintains a disengaged state, and power is not transmitted from the outer ring 12 to the inner ring 11 and shaft portion 1, and the outer ring 12 is in an idling state.

[0035] In other words, when in a non-excited state, regardless of whether the outer ring 12 rotates forward or backward, the retainer 14 is rotated by the centering spring 15, so that the disengaged state of the engagement type clutch 10 is maintained and no power is transmitted from the outer ring 12 to the inner ring 11, shaft portion 1, or case 2, and the outer ring 12 is in an idling state in which it can rotate freely.

[0036] On the other hand, when the electromagnet 23 is energized, the electromagnet 23 enters an excited state that generates a magnetic circuit passing through the field core 25 and the armature 22, and attracts the armature 22 toward the field core 25 against the elastic force of the separation spring 24, and the armature 22 compresses the separation spring 24 in the axial direction and presses it against the end face of the field core 25. At this time, the armature 22 and the cage 14 enter a non-rotatable state due to the frictional resistance of the contact surfaces of the armature 22 and the field core 25. Therefore, in the excited state, when the outer ring 12 rotates slightly, the engagement type clutch 10 enters an engaged state, and power is transmitted from the outer ring 12 to the inner ring 11 and the shaft portion 1 via the engagement type clutch 10, and the rotation of the outer ring 12 is stopped (rotation stopped state).

[0037] That is, in the excited state, when the outer ring 12 rotates in either the forward or reverse direction, a braking force due to frictional resistance between the armature 22 and the field core 25 acts on the cage 14, pushing one of the pair of hooks 15b of the centering spring 15 in the circumferential direction and bending it, causing relative rotation with the cage 14. As a result, the roller 13 held by the cage 14 moves relatively toward the narrow portion of the wedge-shaped space, the engagement type clutch 10 enters an engaged state, and the outer ring 12 stops rotating.

[0038] This power transmission device can switch between transmitting and cutting off power from the input member to the stationary member (case 2) by combining the operations of the above-mentioned engagement clutch 10 and electromagnetic clutch 20, thereby stopping the rotationally driven input member at any timing.

[0039] Here, the inner ring 11 is prevented from rotating with respect to the electromagnet 23 by inserting the shaft portion 1 into the inner diameter of the field core 25. That is, the inner ring 11 is immobile in the circumferential and axial directions with respect to the case 2. In the embodiment, a gap w is set between the inner diameter of the field core 25 and the outer diameter of the shaft portion 1 of the inner ring 11, and a friction locking material 40 is arranged in the gap w to restrict the relative rotation of the inner ring 11 with respect to the electromagnet 23. At this time, for example, it is possible to restrict the rotation of the inner ring 11 by directly press-fitting the shaft portion 1 into the field core 25, but in this case, magnetic leakage from the electromagnet 23 to the inner ring 11 is unavoidable. For this reason, a space (gap w) is provided between the inner diameter of the field core 25 and the outer diameter of the shaft portion 1, and a friction locking material 40 made of a separate member is arranged in the space, thereby suppressing magnetic leakage. This makes it possible to reduce the size of the electromagnet. In addition, the friction locking material 40 can be interposed to restrict the relative rotation of the inner ring 11 around the axis with respect to the field core 25.

[0040] The friction locking material 40 preferably covers the entire circumference of the shaft portion 1, and also preferably covers as long as possible of the insertion length (axial insertion length) of the shaft portion 1 into the inner diameter of the field core 25. It is more preferable that the friction locking material 40 is made of a non-magnetic material. Examples of non-magnetic materials that can be used include non-magnetic metals such as non-magnetic steel, and non-magnetic resins.

[0041] Here, the friction locking member 40 may be, for example, a ring-shaped member that applies a spring load to the inner diameter of the field core 25 and the outer diameter of the shaft portion 1 along the radial direction of the bearing. An example of a ring-shaped member that applies a spring load is an annular member such as a tolerance ring. Depending on the spring load of the tolerance ring, it is possible to make it function as a limiter that allows rotation above a certain torque, and setting it in this way also reduces the burden on the device caused by excessive torque.

[0042] The lid 5 is fixed to one end side (opposite the armature 22 side) of the field core 25 of the electromagnet 23 by a method such as welding. The lid 5 may be a member separate from the field core 25 that is fixed to the field core 25, or may be molded as a member integral with the field core 25.

[0043] The lid 5 is provided with one or more holes 5b, and the case 2 is provided with a screw hole 4a at a position facing the holes. The screw hole 4a is provided in a flange portion 4 provided at one end of the case 2. By inserting and tightening a fixing screw 7 into the hole 5b of the lid 5 and the screw hole 4a of the case 2, the electromagnet 23 can be fixed to the case 2 so that it cannot rotate. Because the electromagnet 23 can be fixed to the case 2, the inner ring 11 and the shaft portion 1 can be indirectly fixed to the case 2.

[0044] The gap between the lid 5 and the case 2 is sealed with a sealant 6. As the sealant 6, an O-ring or the like that seals the gap between the case 2 and the lid 5 all around the axis is preferable. The presence of the sealant 6 can prevent foreign matter from entering the inside of the case 2.

[0045] The fixing structure of the electromagnet 23 to the case 2 is not limited to the fixing structure via the lid 5, and other structures may be adopted.

[0046] Fig. 3 shows a power transmission device of a second embodiment. This second embodiment is based on the excitation type power transmission device of the first embodiment, but is modified to a non-excitation type. Differences from the first embodiment will be described below. The engagement type clutch 10 of the second embodiment has an inner ring fixed and an outer ring rotating, like the first embodiment, but the basic structure for switching between a disengaged state and an engaged state is similar to that of the first embodiment.

[0047] That is, first, the cage 14 is assembled so that its axial movement is restricted with respect to the inner ring 11 and it is supported so as to be movable in the circumferential direction. Although not shown, a plurality of cam surfaces are formed on the outer peripheral surface 11a of the inner ring 11, the inner peripheral surface 12b of the outer ring 12 is a cylindrical surface, and the rollers 13 are arranged one by one in the wedge-shaped spaces formed between each cam surface and the cylindrical surface of the inner peripheral surface 12b of the outer ring 12. The centering spring 15 has a C-shaped annular portion 15a fitted into an annular groove 11b formed on an end face of a step portion of the inner ring 11, and a pair of hooks 15b inserted into the radial groove 11c of the inner ring 11 and the cage groove 14c of the cage 14, and is in contact with the inner surfaces of the radial groove 11c at both ends in the circumferential direction and the inner surfaces of the cage groove 14c at both ends in the circumferential direction, respectively.

[0048] Also, unlike the first embodiment, the electromagnetic clutch 20 employs a disk-shaped intermediate plate 21 fitted to the outer periphery of the shaft portion 1 at one end side of the engagement type clutch 10. The intermediate plate 21 is fitted to the outer periphery of the shaft portion 1 in a state in which it can rotate freely but cannot move in the axial direction, and also plays a role in preventing the centering spring 15 of the engagement type clutch 10 from slipping out of the inner ring 11. An engagement protrusion 21a having an L-shaped cross section formed on the outer periphery of the intermediate plate 21 is inserted into both an engagement recess 14e formed in the retainer 14 and an axial hole 22a formed in the armature 22 without any circumferential gap. That is, the retainer 14 and the armature 22 are engaged in the circumferential direction via the intermediate plate 21. The separation spring 24 presses the armature 22 against the outer ring 12, which is the rotating ring of the engagement type clutch 10.

[0049] When the electromagnetic clutch 20 is in an unexcited state with no current passing through it, the armature 22 is pressed against the outer ring 12. Therefore, when the outer ring 12 rotates slightly, the retainer 14, which is engaged with the armature 22 circumferentially, also rotates slightly, causing the engagement type clutch 10 to enter an engaged state. Power is then transmitted from the outer ring 12 via the engagement type clutch 10 to the inner ring 11 and shaft portion 1, and the rotation of the outer ring 12 is stopped.

[0050] When current is applied to the electromagnetic clutch 20 to place it in an excited state, the armature 22 is attracted to the field core 25 and moves away from the outer ring 12, so that the engagement type clutch 10 enters a disengaged state, power is not transmitted from the outer ring 12 to the inner ring 11 and the shaft portion 1, and the outer ring 12 enters a free-spinning state.

[0051] 4 shows a modification of the second embodiment. In this modification, a friction plate 32 that engages with the intermediate plate 21 in the circumferential direction is fixed to the surface on the other end side of the armature 22 of the electromagnetic clutch 20 by adhesion or the like, and the axial hole 22a of the armature 22 is eliminated. That is, the engagement protrusion 21a having an L-shaped cross section formed on the outer periphery of the intermediate plate 21 is inserted into both the engagement recess 14e formed in the cage 14 and the axial hole 32a formed in the friction plate 32 without any circumferential gap. As a result, the armature 22 is pressed against the outer ring 12 via the friction plate 32, and is engaged with the cage 14 in the circumferential direction via the friction plate 32 and the intermediate plate 21. By using a friction plate 32 that has a larger friction resistance with the outer ring 12 than the armature 22, the stopping operation of the outer ring 12 due to the power transmission from the outer ring 12 to the inner ring 11 and the shaft portion 1 can be more reliably performed in the non-excited state.

[0052] In each of the above embodiments, the first clutch 10 is an engagement type clutch using rollers as engagement elements, but the configuration of the first clutch 10 is not limited to these embodiments. The first clutch 10 may be any clutch that can be switched between an engaged state and a disengaged state by the electromagnetic second clutch 20, and may be, for example, an engagement type clutch using engagement elements other than rollers, or may be a friction clutch such as a wet clutch (for example, a wet multi-plate clutch) or a dry clutch (for example, a dry single-plate clutch), or may be a dog clutch. When a friction clutch is used as the first clutch 10, for example, a ball cam may be used as a mechanism for engaging and disengaging the clutch.

[0053] The operation of a friction clutch using a ball cam will be explained by taking an excitation type power transmission device as an example. In the following, a friction clutch will be used instead of the engagement type clutch in the embodiment shown in Figures 1, 3 and 4, and members having the same functions as those shown in Figures 1, 3 and 4 will be assigned the same reference numerals.

[0054] An outer ring 12 as an input member and an inner ring 11 as a fixed member are assembled in the housing. An input clutch plate is attached to the outer ring 12, and an output clutch plate is attached to the inner ring 11, and they are arranged alternately along the axial direction. A pressure plate is provided between the input clutch plate and the output clutch plate and the armature 22, and the pressure plate is prevented from rotating on the outer ring 12 and is supported by the outer ring 12 so as to be movable in the axial direction. A ball cam is also provided between the opposing surfaces of the pressure plate and the armature 22. The ball cam is configured to have an arc-shaped cam groove extending in the direction around the axis on each of the opposing surfaces of the pressure plate and the armature 22, and a ball is assembled between the cam grooves. The cam grooves are gradually shallower from the center in the arc direction to both ends.

[0055] When the electromagnetic clutch 20 is energized and in an excited state, the armature 22 is attracted to the field core 25. When the outer ring 12, which is the input side, rotates relative to the armature 22, the pressure plate moves in the axial direction due to the function of the ball cam, pushing the input side clutch plate and the output side clutch plate in a direction to approach each other, and the first clutch 10 is engaged. At this time, when the outer ring 12 rotates, power is transmitted from the outer ring 12 via the first clutch 10 to the inner ring 11 and shaft portion 1, and the rotation of the outer ring 12 is stopped.

[0056] When the electromagnetic clutch 20 is de-energized, the adhesion between the field core 25 and the armature 22 is released. With the release of adhesion, the recoil spring 24 presses the armature 22 toward the pressure plate, and the pressure plate is also pressed from the clutch plate side. As a result, the cam groove presses the ball, causing the armature 22 and the pressure plate to rotate relative to each other, and the ball is returned to the neutral position located in the center of the cam groove. Therefore, the axial force load on the clutch plate is released and the first clutch 10 is in a disengaged state. At this time, even if the outer ring 12 rotates, the rotation is not transmitted to the inner ring 11 and the shaft 1, and only the outer ring 12 rotates idly.

[0057] In the above example in which a friction clutch is used as the first clutch 10, a gap w is set between the inner diameter of the field core 25 and the outer diameter of the shaft portion 1 of the inner ring 11, and a friction locking material 40 is disposed in the gap w to regulate the relative rotation of the inner ring 11 with respect to the electromagnet 23, in the same manner.

[0058] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0059] The power transmission device of the present invention can be widely used in drive parts, steering devices, etc. of vehicles (including multipurpose vehicles), ships, construction machines, etc. [Explanation of symbols]

[0060] 1 Shaft 2 Cases 5 Lid (flange) 10 Engagement type clutch (first clutch) 11. Inner Circle 12 Outer ring 13 Roller (engagement element) 14 Cage 20 Electromagnetic clutch (second clutch) 22 Armature 23 Electromagnet 24 Breakup spring 25 Field Core 27 Solenoid coil 40 Friction locking material

Claims

1. the first clutch (10) is disposed between an input side member that is driven to rotate, a stationary member that is stationary relative to the input side member, an inner ring (11) that is fixed to the stationary member, and an outer ring (12) that is fixed to the input side member, and an electromagnetic second clutch (20) that switches the first clutch (10) between an engaged state and a disengaged state; The second clutch (20) has an armature (22), an electromagnet (23) having a solenoid coil (27) wound around an annular field core (25) facing the armature (22) with a predetermined gap in the axial direction, and a separation spring (24) that urges the armature (22) in a direction away from the electromagnet (23), and when current is applied to the electromagnet (23), the armature (22) is attracted to the field core (25) to bring the first clutch (10) into an engaged state, and when current is not applied to the electromagnet (23), the armature (22) is separated from the electromagnet (23) to bring the first clutch (10) into a disengaged state; A gap (w) is provided between the inner diameter of the field core (25) and the outer diameter of the shaft portion (1) provided on the inner ring (11), and a friction locking material (40) is disposed in the gap (w) to regulate the rotation of the inner ring (11).

2. the first clutch (10) is disposed between an input side member that is driven to rotate, a stationary member that is stationary relative to the input side member, an inner ring (11) that is fixed to the stationary member, and an outer ring (12) that is fixed to the input side member, and an electromagnetic second clutch (20) that switches the first clutch (10) between an engaged state and a disengaged state; The second clutch (20) has an armature (22), an electromagnet (23) having a solenoid coil (27) wound around an annular field core (25) facing the armature (22) with a predetermined gap in the axial direction, and a separation spring (24) that urges the armature (22) in a direction away from the electromagnet (23), and when current is applied to the electromagnet (23), the armature (22) is attracted to the field core (25) to disengage the first clutch (10), and when current is not applied to the electromagnet (23), the armature (22) is separated from the electromagnet (23) to engage the first clutch (10), in a non-excitation type power transmission device, A gap (w) is provided between the inner diameter of the field core (25) and the outer diameter of the shaft portion (1) provided on the inner ring (11), and a friction locking material (40) is disposed in the gap (w) to regulate the rotation of the inner ring (11).

3. 3. The power transmission device according to claim 1 or 2, wherein the first clutch (10) is an engagement-type clutch assembled between the outer ring (11) and the inner ring (12) with an engagement element (13) held by a retainer (14), the retainer (14) engaging with the armature (22) in the circumferential direction, and the retainer (14) moving the engagement element (13) relative to the inner ring (11) and the outer ring (12) in the circumferential direction, thereby switching between an engaged state in which the engagement element (13) engages with the inner ring (11) and the outer ring (12) and a disengaged state in which the engagement element (13) does not engage with the inner ring (11) and the outer ring (12).

4. 3. A power transmission device according to claim 1 or 2, wherein the electromagnet (23) is provided with a flange (5) separate from or integral with the field core (25), and the rotation of the electromagnet (23) is regulated by fixing the flange (5) to the stationary member.

5. 5. The power transmission device according to claim 4, wherein a gap between the flange (5) and the stationary member is sealed with a seal material (6).

6. 3. The power transmission device according to claim 1, wherein the friction locking member (40) is a ring-shaped member that applies a spring load to the inner diameter of the field core (25) and the outer diameter of the shaft portion (1) along the radial direction of the bearing.

7. 3. The power transmission device according to claim 1, wherein the frictional engaging member (4) is made of a non-magnetic material.

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