JP2011122679A - Electromagnetic clutch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic clutch capable of equalizing a cam force which acts on a friction surface of an armature or making the cam force act mainly on the outer peripheral side from the end of the inner peripheral side of the friction surface of the armature. <P>SOLUTION: The electromagnetic clutch 1 includes: an electromagnetic coil 74, which generates a magnetic force; the armature 60, which is moved in the axial direction by the magnetic force of the electromagnetic coil 74; a rear housing 22, which contacts the armature 60 by the axial movement of the armature 60; a first cam member 61 whose relative rotation with the armature 60 is restrained; and a second cam member 62, which causes the first cam member 61 to generate the cam force that presses the armature 60 toward the rear housing 22 by the relative rotation with the first cam member 61. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electromagnetic clutch for controlling torque transmission between rotating members or controlling an action of a braking force on the rotating members.

  Conventionally, an armature in which a cam groove is formed is attracted by the magnetic force of an electromagnetic coil, the cam mechanism is operated by friction at a contact portion with other members generated by the attraction, and the cam member is made stronger by the cam force of the cam mechanism. 2. Description of the Related Art There is known an electromagnetic clutch that controls torque transmission between rotating members by a frictional force generated by pressing the member. (For example, refer to Patent Document 1).

  The electromagnetic clutch described in Patent Document 1 is applied to a drive system on the rear wheel side of a four-wheel drive vehicle configured to drive front wheels with an engine and drive rear wheels with an electric motor, and stop the electric motor. Sometimes it is arranged between the output shaft and the gears constituting the reduction gear train in order to cut off the connection between the differential device of the rear wheel and the electric motor to reduce the running resistance.

  This electromagnetic clutch includes an electromagnetic coil, an armature that is attracted to the electromagnetic coil side by the magnetic force of the electromagnetic coil and frictionally contacts a disk-shaped member that rotates integrally with the output shaft, and a cam follower that is interposed between the armature and the gear. I have. A cam groove is formed on each of the facing surfaces of the armature and the gear, and the armature and the gear constitute a cam mechanism together with the cam follower.

  This armature has a disc shape in which an insertion hole through which the output is inserted is formed at the center, and a friction surface that frictionally engages the disc-shaped member on the surface opposite to the surface on which the cam groove is formed. Is formed. This friction surface is formed on the outer peripheral side of the cam groove.

  When the electromagnetic coil is energized during traveling of the vehicle, the armature is attracted to the disk-shaped member and brought into frictional contact, and is rotated relative to the gear by the frictional force. This relative rotation causes the cam follower to roll in the cam groove, and the cam force of the cam mechanism causes the armature to be more strongly pressed against the disk-shaped member and frictionally engaged, so that the torque of the electric motor is transmitted to the differential side. .

  On the other hand, when the electric motor is stopped while the electromagnetic coil is not energized, the cam mechanism is neutralized (non-actuated) by the force of the return spring, and the frictional engagement of the cam member is released. As a result, the connection between the electric motor and the differential device is cut off.

JP 2004-17807 A

  The armature of the electromagnetic clutch configured as described above receives an axial cam force by a cam groove formed on the inner peripheral side of the friction surface, and the friction surface frictionally engages the friction counterpart member. Therefore, the armature is elastically deformed by the cam force so that the outer peripheral side is separated from the friction counterpart member with the inner peripheral side of the friction surface as a fulcrum. For this reason, the pressing force that frictionally engages the armature mainly acts on the end portion on the inner peripheral side of the friction surface, and in the extreme case, the outer peripheral side floats from the friction counterpart member. As is well known, the torque T is indicated by the product (T = F × r) of the force F applied to the object and the distance r to the point where the force is applied as seen from the axis of rotation, so that the armature is frictionally engaged. The part where the cam force acts is more effective on the outer peripheral side than on the inner peripheral side.

  However, in the armature of the electromagnetic clutch configured as described above, the cam force mainly acts on the inner peripheral end of the friction surface. Therefore, in order to prevent the friction surface from slipping during torque transmission, the armature diameter is reduced. It is necessary to increase the size or to reduce the angle of the cam surface relative to the circumferential direction of the armature. Increasing the armature diameter limits the size and weight of the device, and reducing the cam surface angle increases the relative rotation angle from the neutral position of the cam mechanism until cam force is generated on the cam member, resulting in a response. descend.

  Accordingly, the present invention provides an electromagnetic clutch capable of equalizing cam force acting on the friction surface of the armature or allowing the cam force to mainly act on the outer peripheral side of the inner peripheral side end of the armature friction surface. The purpose is to do.

  In order to achieve the above object, an electromagnetic clutch according to the present invention includes an electromagnetic coil that generates a magnetic force, an armature that moves in an axial direction by the magnetic force, a friction member that contacts the armature by the axial movement of the armature, and the armature The first cam member whose relative rotation with the first cam member and the first cam member relative to each other generate a cam force that presses the armature toward the friction member on the first cam member. And a cam member.

  According to this configuration, the armature receives the cam force via the first cam member that is separate from the armature.

  Moreover, the said armature is a cyclic | annular form by which the through-hole was formed in center part, and the said 1st cam member is good to press the said armature on the outer peripheral side rather than the inner peripheral side edge part of the said armature.

  According to this configuration, the pressing force by the first cam member does not concentrate on the inner peripheral side end portion of the armature.

  The friction member is frictionally engaged with one side surface of the armature by friction surfaces formed on the inner peripheral side and the outer peripheral side of the annular recess opened to the armature side, and the electromagnetic coil is placed in the annular recess. It is good that it is the yoke which accommodates.

  According to this configuration, a frictional force is generated in the armature by contacting the friction surfaces on the inner and outer peripheral sides of the yoke.

  Further, the first cam member generates a maximum load that presses the other side surface of the armature in a radial region between an inner peripheral side and an outer peripheral side friction surface of the annular recess of the yoke. Configure.

  According to this configuration, the load of the first cam member is distributed to the inner and outer friction surfaces of the annular recess.

  According to the present invention, the cam force acting on the friction surface of the armature can be equalized, or the cam force can be mainly applied to the outer peripheral side of the inner peripheral side end portion of the armature friction surface.

FIG. 1 is a schematic diagram showing a configuration of a driving force transmission system of a four-wheel drive vehicle to which an electromagnetic clutch according to a first embodiment of the present invention is applied. FIG. 2 is a cross-sectional view showing the configuration of the driving force transmission device according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram showing an operating state and a non-operating state of the cam mechanism according to the first embodiment of the present invention. FIG. 4 is an explanatory view showing an operating state and a non-operating state of an armature cam as a comparative example. FIG. 5 is a schematic diagram showing a configuration of an electromagnetic clutch according to a second embodiment of the present invention. FIG. 6 is an explanatory view showing an armature of an electromagnetic clutch according to a second embodiment of the present invention. FIG. 7 is a schematic diagram showing a configuration of an electromagnetic clutch according to a third embodiment of the present invention.

[First Embodiment]
FIG. 1 shows a schematic configuration of a driving force transmission system of a four-wheel drive vehicle to which an electromagnetic clutch according to a first embodiment of the present invention is applied. As shown in FIG. 1, a four-wheel drive vehicle 101 includes an engine 102 as a drive source, a transaxle 103 that distributes the output of the engine 102 to a pair of front axle shafts 104 and a propeller shaft 106, and a pair of front axle shafts 104. A driving force transmission device 1 for transmitting the torque of a pair of front wheels 105 and a propeller shaft 106 connected to each to a drive pinion shaft 108, and a rear differential 109 for distributing the torque transmitted to the drive pinion shaft 108 to a pair of rear axle shafts 110. , And a pair of rear wheels 111 connected to each of the pair of rear axle shafts 110.

  The driving force transmission device 1 is supported inside a differential carrier 107 fixed to a vehicle body (not shown) of the four-wheel drive vehicle 101, and can control torque transmission between the propeller shaft 106 and the drive pinion shaft 108. It is configured. When the driving force transmission device 1 connects the propeller shaft 106 and the drive pinion shaft 108 so that torque can be transmitted, the four-wheel drive vehicle 101 enters a four-wheel drive state, and when this connection is released, the four-wheel drive vehicle 101 enters a two-wheel drive state. Become.

  The four-wheel drive vehicle 101 is equipped with a controller 112 that controls the driving force transmission device 1. The controller 112 supplies current to the driving force transmission device 1 based on the rotational speeds of the pair of front wheels 104 and the pair of rear wheels 105, the accelerator opening degree, and the like, and controls torque transmission of the driving force transmission device 1.

(Overall configuration of the driving force transmission device 1)
FIG. 2 is a cross-sectional view illustrating a configuration of the driving force transmission device 1. The driving force transmission device 1 includes a housing 2 that can rotate with respect to a differential carrier 107 (shown in FIG. 1), an inner shaft 3 that is coaxial with and relative to the housing 2, and a housing 2 and an inner shaft. 3 is operated by energization of the main coil 4, the electromagnetic coil 5 that is non-rotatably held with respect to the differential carrier 107, and the electromagnetic coil 5, and generates a pressing force that presses the main clutch 4. The cam mechanism 6 is generally configured. The electromagnetic coil 5, the cam mechanism 6, and the rear housing 22 described later constitute the electromagnetic clutch 10.

(Configuration of housing 2)
The housing 2 includes a front housing 21 and a rear housing 22 coupled so as to rotate integrally with the front housing 21, and is supported inside the differential carrier 107 via a bearing (not shown).

  The front housing 21 is made of, for example, an aluminum alloy that is a nonmagnetic material, and includes a housing space 21a that opens to the rear housing 22 side, and a straight spline fitting portion 21b that is formed on the inner surface of the housing space 21a. The shaft 106 (shown in FIG. 1) is connected to rotate integrally. The accommodating space 21a is filled with lubricating oil at a filling rate of about 80%.

  The rear housing 22 is integrally coupled to the outer member 221 made of a magnetic material such as carbon steel (for example, S35C, S10C) screwed to the inner peripheral surface of the opening of the front housing 21 and the inner side of the outer member 221 by welding or the like. An intermediate member 222 made of a non-magnetic material such as stainless steel, and an inner member 223 made of a magnetic material such as carbon steel integrally joined to the inside of the intermediate member 222 by welding or the like.

  The rear housing 22 is formed with an annular housing space 22 a that opens in the same direction as the opening direction of the housing space 21 a of the front housing 21. Further, a friction surface 22b that frictionally engages an armature 60 described later is formed on the side surface of the rear housing 22 opposite to the accommodation space 22a.

(Configuration of inner shaft 3)
The inner shaft 3 is supported inside the housing 2 by a ball bearing 210 interposed between the front housing 21 and a needle bearing 220 interposed between the rear housing 22.

  The inner shaft 3 is formed with a first hollow portion 3b extending in the axial direction from the end surface 3a on the rear housing 22 side, and a straight spline fitting portion 3c is provided on the inner surface of the first hollow portion 3b. The first hollow portion 3b is inserted with the tip of a drive pinion shaft 108 (shown in FIG. 1), and a straight spline fitting portion (not shown) formed at the tip of the drive pinion shaft 108 is the first. It fits into the straight spline fitting part 3c of the hollow part 3b.

  Further, the inner shaft 3 is formed with a second hollow portion 3e extending in the axial direction from the end surface 3d on the front housing 21 side, and lubricating oil is accommodated in the second hollow portion 3e. The first hollow portion 3b and the second hollow portion 3e are separated by a wall portion 3f.

  Further, on the outer surface of the inner shaft 3, a straight spline fitting portion 3g is formed at a portion facing the straight spline fitting portion 21b of the front housing 21.

(Configuration of main clutch 4)
The main clutch 4 has a plurality of outer clutch plates 41 and a plurality of inner clutch plates 42 arranged alternately with the outer clutch plates 41, and both the clutch plates slide in an accommodation space 21a filled with lubricating oil. It is configured as a wet multi-plate clutch.

  The outer clutch plate 41 has a spline fitting portion 41 a on the outer periphery thereof, and the spline fitting portion 41 a is fitted to the straight spline fitting portion 21 b of the front housing 21. As a result, the outer clutch plate 41 is axially movable with respect to the housing 2 and is connected to rotate integrally with the housing 2.

  The inner clutch plate 42 has a spline fitting portion 42 a on its inner peripheral portion, and the spline fitting portion 42 a is fitted to the straight spline fitting portion 3 g of the inner shaft 3. Thereby, the inner clutch plate 42 is axially movable with respect to the inner shaft 3 and is connected so as to rotate integrally with the inner shaft 3. Further, the inner clutch plate 42 has holes 42b through which lubricating oil is circulated at a plurality of locations in the circumferential direction.

(Configuration of electromagnetic coil 5)
The electromagnetic coil 5 is held by a yoke 51 made of a magnetic material such as carbon steel fixed to a differential carrier 107 (shown in FIG. 1), and is disposed in a housing space 22 a of the rear housing 22. The yoke 51 is provided between the inner member 223 with an air gap 51a interposed between the yoke 51 and the inner peripheral surface of the outer member 221 of the rear housing 22 and an air gap 51b between the inner member 223 and the inner member 223. The rear housing 22 is supported via a seal bearing 52.

  The yoke 51 is formed with an annular housing space 51c that opens toward the bottom in the axial direction of the housing space 22a, and the electromagnetic coil 5 is held in the housing space 51c. A current supplied from an electric wire 5 a inserted through a hole 51 d formed in the yoke 51 is energized in the winding of the electromagnetic coil 5.

(Configuration of cam mechanism 6)
The cam mechanism 6 is disposed between the main clutch 4 and the rear housing 22, and relative rotation between the armature 60 attracted to the rear housing 22 side by the magnetic force generated by energization of the electromagnetic coil 5 and the armature 60 is restricted. The first cam member 61, the second cam member 62 that generates a cam force by the relative rotation of the first cam member 61, and the spherical cam follower 63 that is interposed between the first cam member 61 and the second cam member 62. And is configured.

  The first cam member 61 is disposed closer to the rear housing 22 than the cam follower 63, and the armature 60 is disposed between the first cam member 61 and the rear housing 22. Further, the second cam member 62 is disposed on the main clutch 4 side with respect to the cam follower 63. The armature 60, the first cam member 61, and the second cam member 62 are disposed coaxially with the rotation axis O of the inner shaft 3.

(Configuration of armature 60)
The armature 60 is a plate-like member made of a magnetic material such as carbon steel (for example, S35C, S10C), and is formed in an annular shape in which a through hole 601 is formed at the center. A spline fitting portion 602 extending in the axial direction is provided on the inner periphery of the through hole 601. An annular friction surface 60 a that contacts the friction surface 22 b is formed on the surface of the armature 60 that faces the rear housing 22. An annular pressed surface 60b that is pressed by the first cam member 61 is formed on the side surface opposite to the side on which the friction surface 60a is formed.

  Among the surfaces of the armature 60, at least the friction surface 60a can reduce wear due to friction or suppress the occurrence of stick-slip phenomenon (a phenomenon in which chatter vibration occurs due to repeated relative slip and catch). The target surface treatment is performed to improve the friction characteristics. Examples of such surface treatment include diamond-like carbon (DLC) film formation treatment and nitrogen tech treatment (treatment for forming an oxide film on the surface in succession to gas soft nitriding treatment (Nitrotech is a registered trademark)). Can be mentioned.

  The armature 60 is biased toward the first cam member 61 by a disc spring 64. The disc spring 64 is restricted in axial movement by one end in the axial direction coming into contact with the snap ring 31 fitted on the outer peripheral surface of the inner shaft 3, and the other end in the axial direction is located inside the friction surface 60 a of the armature 60. It is in contact with the circumferential side surface 60c.

(Configuration of the first cam member 61)
The first cam member 61 is an annular member made of a metal material such as carbon steel, and is subjected to hardening treatment such as quenching and tempering and gas soft nitriding, and is externally fitted to the inner shaft 3. The first cam member 61 is provided on the outer peripheral side of the cam portion 611, the spline fitting portion 612 provided on one side (rear housing 22 side) in the axial direction of the cam portion 611, and the cam portion 611. The pressing part 613 is integrally formed.

  The cam portion 611 is formed with a plurality of cam grooves 611a on which the cam follower 63 rolls. The cam groove 611a extends in the circumferential direction of the first cam member 61, and is formed such that the axial depth is the deepest at the center and becomes shallower toward the end in the circumferential direction.

  The spline fitting portion 612 has a plurality of spline teeth extending in the axial direction on the outer peripheral surface thereof, and is fitted with the spline fitting portion 602 of the armature 60. For this reason, the relative rotation of the armature 60 and the first cam member 61 is restricted, and the armature 60 can move in the axial direction with respect to the first cam member 61.

  The pressing portion 613 includes an annular portion 614 provided on the outer peripheral side of the cam portion 611, and a flange portion 615 formed so as to protrude from the outer peripheral end portion of the annular portion 614 toward the armature 60 side in the axial direction. A pressing surface 615 a that abuts against the pressed surface 60 b of the armature 60 is formed at the distal end in the axial direction of the flange portion 615.

  The pressing portion 613 presses the armature 60 on the outer peripheral side with respect to the end portion 600 a on the inner peripheral side of the friction surface 60 a of the armature 60. The pressing portion 613 presses the armature 60 in a radial region including at least the radial center 600b of the friction surface 60a of the armature 60.

(Configuration of the second cam member 62)
The second cam member 62 is an annular member made of a metal material such as carbon steel, and is externally fitted to the inner shaft 3. The second cam member 62 is provided on the cam portion 621, the spline fitting portion 622 provided on one side (main clutch 4 side) of the cam portion 621, and the outer peripheral side of the spline fitting portion 622. The pressed portion 623 is integrally formed.

  The cam portion 621 is formed with a plurality of cam grooves 621a on which the cam follower 63 rolls. The cam groove 621a extends in the circumferential direction of the second cam member 62, and is formed so that the axial depth at the center thereof is the deepest and becomes shallower toward the end in the circumferential direction.

  The spline fitting portion 622 has a plurality of spline teeth extending in the axial direction on the inner peripheral surface thereof, and is fitted to one end of the straight spline fitting portion 3 g of the inner shaft 3. For this reason, the second cam member 62 is axially movable with the inner shaft 3 and is connected to rotate integrally with the inner shaft 3.

  The pressing portion 623 is formed with a pressing surface 623 a that faces the inner clutch plate 42 that is positioned closest to the cam mechanism 6 among the plurality of inner clutch plates 42 of the main clutch 4.

  A disc spring 65 is disposed between the stepped portion 3 h formed on the inner side of the spline fitting portion 622 and on the rear housing 22 side of the straight spline fitting portion 3 g of the inner shaft 3 and the cam portion 621. Has been. The disc spring 65 biases the second cam member 62 toward the first cam member 61.

  The cam follower 63 is made of a metal material such as carbon steel, and is sandwiched between the cam groove 611 a of the first cam member 61 and the cam groove 621 a of the second cam member 62. When the first cam member 61 and the second cam member 62 rotate relative to each other and the cam follower 63 rolls in the circumferential direction from the position (neutral position) of the cam groove 611a and the cam groove 621a in the circumferential direction, the first cam member A cam force that separates 61 and the second cam member 62 in the axial direction is generated.

(Operation of the driving force transmission device 1)
Next, the operation of the driving force transmission device 1 will be described. When the engine 102 of the four-wheel drive vehicle 101 is not started, the electromagnetic coil 5 is not energized, the armature 60 is not in contact with the rear housing 22 by the biasing force of the disc spring 64, and the cam mechanism 6 is operated. Not done.

  When the engine 102 is started and the four-wheel drive vehicle 101 starts, the controller 112 supplies a current to the electromagnetic coil 5 of the driving force transmission device 1 so that the front wheel 105 and the rear wheel 111 are driven. Supply and energize. This energization generates a magnetic flux M in a magnetic path formed by the yoke 51, the outer member 221 of the rear housing 22, the armature 60, and the inner member 223 of the rear housing 22, as indicated by a dotted line in FIG. 2. Due to the magnetic force of the magnetic flux M, the armature 60 moves in the axial direction so as to be attracted to the rear housing 22 against the biasing force of the disc spring 64, and the friction surface 60 a of the armature 60 rubs against the friction surface 22 b of the rear housing 22. Contact.

  As described above, the relative rotation of the armature 60 and the first cam member 61 is restricted by spline fitting, and the second cam member is configured to rotate integrally with the inner shaft 3. When the housing 2 and the inner shaft 3 are differentially rotated while the housing 22 is in frictional contact, the cam follower 63 rolls on the cam groove 611a and the cam groove 621a, and the cam mechanism 6 operates. Then, the first cam member 61 presses the armature 60 toward the rear housing 22 by the cam force of the cam mechanism 6. Thereby, the armature 60 is pressed against the rear housing 22 more strongly than when it is attracted to the rear housing 22 by a magnetic force, and is frictionally engaged.

  On the other hand, the second cam member 62 presses the main clutch 4 by the cam force of the cam mechanism 6 and frictionally engages the outer clutch plate 41 and the inner clutch plate 42 so that torque can be transmitted. As a result, the torque of the engine 102 transmitted through the propeller shaft 106 is transmitted to the drive pinion shaft 108, resulting in a four-wheel drive state.

  Further, for example, when the four-wheel drive vehicle 101 is in a steady running state in which the four-wheel drive vehicle 101 goes straight at a constant vehicle speed, the controller 112 supplies the electromagnetic coil 5 to a two-wheel drive state in which only the pair of front wheels 105 are driven to improve fuel efficiency. Shut off the power of the.

  When the energization of the electromagnetic coil 5 is interrupted, the armature 60 is separated from the rear housing 22 by the biasing force of the disc spring 64. Then, there is no force to relatively rotate the first cam member 61 and the second cam member 62, the cam follower 63 rolls to the neutral position, and the cam mechanism 6 becomes inoperative. Then, the second cam member 62 is returned to a position where the main clutch 4 is not pressed by the biasing force of the disc spring 65. As a result, the frictional engagement between the outer clutch plate 41 and the inner clutch plate 42 is released, and a two-wheel drive state is established.

  FIG. 3 is a diagram showing the relative positions and shapes of the armature 60 and the first cam member 61 in outline. When the cam mechanism 6 is operated, the first cam member 61 is shown by a solid line, and the cam mechanism 6 is not shown. The first cam member 61 at the time of operation is indicated by a two-dot chain line. As shown in this figure, when the cam mechanism 6 is actuated, the first cam member 61 moves to the pressing portion 613 due to the displacement in the radial direction between the cam groove 611a of the cam portion 611 and the pressing surface 615a of the pressing portion 613. On the other hand, the cam portion 611 bends so as to be displaced toward the armature 60, but this bend hardly affects the posture of the armature 60.

  In addition, as shown in the graph of FIG. 3, the radial distribution of the load in which the first cam member 61 presses the armature 60 has the largest load at the end portion on the inner peripheral side of the pressing portion 613 and moves toward the outer peripheral side. As it gets smaller. In this figure, the amount of deformation of the first cam member 61 is exaggerated.

  FIG. 4 is a diagram showing an outline of a radial sectional shape of an annular armature cam 200 having a cam groove and a friction surface formed as one member as a comparative example. In this figure, the outline of the armature cam 200 when the cam force is applied is indicated by a solid line, and the outline of the armature cam 200 when the cam force is not applied is indicated by a two-dot chain line.

  The armature cam 200 is an annular member made of a metal material such as carbon steel in which the cam portion 201 and the pressing portion 202 are integrally formed. The cam portion 201 has a cam groove 201a, and the pressing portion 202 has no illustration. Friction surfaces 202a that frictionally engage with a friction counterpart member (for example, the rear housing 22) are formed. The pressing portion 202 is provided on the outer peripheral side of the cam portion 201, and the cam groove 201a and the friction surface 202a are respectively formed on opposite surfaces in the axial direction.

  When the armature cam 200 receives an axial cam force F from a cam follower (not shown) that rolls in the cam groove 201a, the armature cam 200 rotates with the inner peripheral end 202b of the friction surface 202a as a fulcrum. Deform. Due to this deformation, the outer peripheral side of the friction surface 202a is separated from the friction counterpart member in the axial direction, and the cam force F is concentrated on the inner peripheral side of the friction surface 202a and is pressed against the friction counterpart member on the outer periphery side. The force is weaker than the inner circumference.

(Effects of the first embodiment)
According to the first embodiment of the present invention described above, the following effects can be obtained.

(1) Since the armature 60 and the first cam member 61 are separate bodies, heat treatment and surface treatment suitable for each can be performed. For example, the armature 60 is subjected to a surface treatment for improving the friction characteristics, and the first cam member 61 is subjected to a curing process, so that both the improvement of the friction characteristics and the strength can be achieved.

(2) Since the armature 60 and the first cam member 61 are separate bodies, the influence of the bending of the first cam member 61 upon the operation of the cam mechanism 6 on the posture of the armature 60 is reduced. Compared to a case where the cam mechanism is constituted by an integral cam member having a friction surface that frictionally engages with the rear housing 22, the friction surface 60 a of the armature 60 abuts in parallel with the friction surface 22 a of the rear housing 22. Thus, the load distribution of the cam force acting on the friction surface 60a of the armature 60 is equalized.

(3) The pressing portion 613 of the first cam member 61 presses the armature 60 on the outer peripheral side with respect to the inner peripheral side end portion 600a of the friction surface 60a of the armature 60. For example, the pressing portion 613 includes the inner portion of the friction surface 60a. Compared with the case where the armature 60 is pressed in a radial region including the peripheral end 600a, the cam force of the cam mechanism 6 is concentrated on the inner peripheral end of the friction surface 60a. Can be suppressed.

(4) Further, when the pressing portion 613 of the first cam member 61 is configured to press the armature 60 in a region including at least the radial center 600b of the friction surface 60a of the armature 60, the cam of the cam mechanism 6 is further increased. It can suppress that force concentrates and acts on the inner peripheral side edge part of the friction surface 60a.

[Second Embodiment]
FIG. 5 shows a schematic configuration of the electromagnetic clutch 11 and its peripheral portion according to the second embodiment of the present invention, where (a) shows the operating state of the electromagnetic clutch 11 and (b) shows the non-operating state of the electromagnetic clutch 11. Each state is shown. The electromagnetic clutch 11 functions as a brake device for preventing the cylindrical rotating member 8 from rotating relative to the casing 9 that is a non-rotating member, and is used, for example, to switch a torque transmission path by a planetary gear mechanism. .

  The electromagnetic clutch 11 includes a rotating member 8, a spherical cam follower 71 that rolls on a cam groove 81a formed in a flange 81 of the rotating member 8, and a cam having a cam groove 72a formed on a surface facing the cam groove 81a. A member 72, an armature 73 that is prevented from rotating around the cam member 72, an electromagnetic coil 74 that generates a magnetic force that moves the armature 73 in the axial direction, and a yoke 75 made of a magnetic material that holds the electromagnetic coil 74 are configured. ing. The cam member 72 is an example of the first cam member of the present invention, and the rotating member 8 is an example of the second cam member of the present invention.

(Configuration of Rotating Member 8)
The rotating member 8 includes a cylindrical portion 80 in which a through-hole through which a shaft (not shown) is inserted is formed on the inner surface, and an annular flange portion that protrudes radially outward from one axial end of the cylindrical portion 80. 81 is integrally formed. A straight spline fitting portion 80 a formed along the rotation axis O ₂ for restricting relative rotation between the shaft and the rotating member 8 is provided on one side in the axial direction of the inner peripheral surface of the cylindrical portion 80. Yes. An inner ring 771 of a ball bearing 77 is fitted to the outer peripheral surface of the cylindrical portion 80 corresponding to the outside of the straight spline fitting portion 80a.

  A cam groove 81a formed on one side surface of the flange portion 81 in the axial direction (the side on which the straight spline fitting portion 80a is formed) extends in the circumferential direction of the rotating member 8, and has an axial depth at the center portion thereof. Is deepest and becomes shallower toward the end in the circumferential direction.

(Configuration of cam member 72)
The cam member 72 is an annular member made of a metal material such as carbon steel, is subjected to hardening treatment such as quenching and tempering and gas soft nitriding, and is externally fitted to the cylindrical portion 80 of the rotating member 8.

  The cam member 72 has the same shape as the first cam member 61 in the first embodiment, and includes a cam portion 721 having a cam groove 72a formed on a surface facing the cam groove 81a, and a shaft of the cam portion 721. A spline fitting portion 722 provided on one side in the direction and having a plurality of spline teeth extending in the axial direction on the outer peripheral portion and a pressing portion 723 provided on the outer peripheral side of the cam portion 721 are integrally formed.

  The pressing portion 723 includes an annular portion 724 provided on the outer peripheral side of the cam portion 721, and a flange portion 725 formed so as to protrude from the outer peripheral end portion of the annular portion 724 toward the armature 73 in the axial direction. A pressing surface 725 a that presses the armature 73 is formed at the axial end of the collar portion 725.

  Cam grooves 81 a are formed in the circumferential portion 81 of the rotating member 8 in at least three locations in the circumferential direction, and the same number of cam grooves 72 a are also formed in the cam portion 721 of the cam member 72. The cam follower 71 is interposed between each cam groove 81 a and the corresponding cam groove 72 a and is held by a retainer 710 disposed between the flange 81 and the cam member 72. The cam member 72 can rotate relative to the rotating member 8 in a range in which the cam follower 71 rolls in the cam groove 72 a and the cam groove 81 a of the rotating member 8.

(Configuration of armature 73)
The armature 73 is a plate-like member made of a magnetic material such as carbon steel (for example, S35C, S10C). The armature 73 has the same shape as the armature 60 in the first embodiment, and has a through hole 731 formed at the center and a plurality of spline teeth extending in the axial direction provided on the inner periphery of the through hole 731. A spline fitting portion 732 is provided. The spline fitting portion 732 is fitted with the spline fitting portion 722 of the cam member 72. Thereby, the relative rotation of the armature 73 and the cam member 72 is restricted, and relative movement in the axial direction is possible.

  Of the both side surfaces of the armature 73 in the axial direction, a pressed surface 73c with which the pressing surface 725a of the pressing portion 723 abuts is formed on the side surface facing the pressing portion 723 of the cam member 72. Further, an inner peripheral friction surface 73a and an outer peripheral friction surface 73b that are frictionally engaged with an inner peripheral friction surface 75a and an outer peripheral friction surface 75b of a yoke 75, which will be described later, are formed on the opposite side surface. . Of the surface of the armature 73, at least the inner peripheral friction surface 73a and the outer peripheral friction surface 73b are subjected to a surface treatment for improving the friction characteristics.

  The armature 73 is urged toward the cam member 72 by a disc spring 76. The disc spring 76 is restricted from moving in the axial direction by a spacer 78 disposed between the disc bearing 76 and the inner ring 771 of the ball bearing 77.

(Configuration of yoke 75)
The yoke 75 is made of a magnetic material such as carbon steel, is disposed so as to face the armature 73 in the axial direction, and is fixed to the casing 9 by a bolt 91 so as not to be relatively rotatable and axially movable. The yoke 75 is formed with an annular recess 750 having a U-shaped cross section that is open toward the armature 73 in the axial direction, and the electromagnetic coil 74 is held in the annular recess 750. An annular inner peripheral friction surface 75a is formed on the inner surface of the annular recess 750 facing the armature 73, and an annular outer friction surface 75b is formed on the outer surface of the annular recess 750 facing the armature 73. Has been.

  An outer ring 772 of a ball bearing 77 is fitted to the inner peripheral surface of the yoke 75, and the yoke 75 supports the rotating member 8 in a rotatable manner. The ball bearing 77 is provided on the inner peripheral surface of the yoke 75 with the axial position of the inner ring 771 fixed by the stepped portion 80 b provided on the outer peripheral surface of the cylindrical portion 80 of the rotating member 8 and the snap ring 773. The axial position of the outer ring 772 is fixed by the stepped portion 75c and the snap ring 774.

  The electromagnetic coil 74 is held in the annular recess 750 of the yoke 75 and is prevented from coming off by a snap ring 751. A current is supplied to the electromagnetic coil 74 by an unillustrated electric wire.

(Pressure structure of the armature 73 by the cam member 72)
FIG. 6 is a diagram showing a state in which the armature 73 is viewed from the side of the yoke 75 in the axial direction. In this figure, the outer circumference circle 73d and the inner circumference circle 73e of the pressed surface 73c corresponding to the back surface of the armature 73 are indicated by broken lines.

  As shown in this figure, the pressed surface 73c of the armature 73 is formed in an annular shape in a radial region between the inner peripheral friction surface 73a and the outer peripheral friction surface 73b. That is, the cam member 72 presses the armature 73 in the axial direction in a radial region between the inner peripheral friction surface 75a and the outer peripheral friction surface 75b of the yoke 75. As a result, the cam force received by the cam member 72 is distributed to the inner peripheral friction surface 73 a and the outer peripheral friction surface 73 b of the armature 73.

  Similarly to the case shown in FIG. 3, the radial distribution of the load in which the cam member 72 presses the armature 73 is the largest at the inner peripheral end of the pressing portion 723. A maximum load for pressing the pressed surface 73c of the armature 73 is generated in a radial region between the inner peripheral friction surface 75a and the outer peripheral friction surface 75b of the yoke 75.

(Operation of electromagnetic clutch 11)
When the electromagnetic coil 74 is energized, a magnetic flux M ₂ is generated in a magnetic path formed by the yoke 75 and the armature 73 as shown by a broken line in FIG. 5A, and the armature 73 is attracted to the yoke 75 side. The inner peripheral friction surface 73a of the armature 73 is in frictional contact with the inner peripheral friction surface 75a of the yoke 75, and the outer peripheral friction surface 73b of the armature 73 is in frictional contact with the outer peripheral friction surface 75b of the yoke 75.

  When the rotating member 8 rotates in this state, the cam follower 71 rolls on the cam groove 81a and the cam groove 72a, and a cam force is generated that separates the cam member 72 in the axial direction with respect to the flange 81 of the rotating member 8. In response to this cam force, the cam member 72 presses the pressed surface 73c of the armature 73 via the pressing surface 725a.

  As a result, the armature 73 is more strongly pressed against the yoke 75, and the frictional forces of the inner peripheral friction surface 73a and the inner peripheral friction surface 75a, and the outer peripheral friction surface 73b and the outer peripheral friction surface 75b increase. Since the yoke 75 cannot rotate relative to the casing 9 as described above, the rotating member 8 is prevented from rotating with respect to the casing 9.

  On the other hand, when the energization to the electromagnetic coil 74 is interrupted, the armature 73 is separated from the yoke 75 by the biasing force of the disc spring 76 as shown in FIG. 5B, and the armature 73 and the yoke 75 are frictionally engaged. Is released. Then, the cam follower 71 moves to the deepest part (neutral position) of the cam groove 72a and the cam groove 81a, and the cam force disappears. Thereby, the rotating member 8 can rotate together with the cam follower 71, the cam member 72, the armature 73, and the disc spring 76.

(Effect of the second embodiment)
According to the second embodiment of the present invention described above, since the armature 73 is directly frictionally engaged with the yoke 75 in addition to the effects (1) to (3) of the first embodiment. The electromagnetic clutch 11 can be configured with a small number of parts. Further, since the cam member 72 presses the armature 73 in the radial direction between the inner peripheral friction surface 75a and the outer peripheral friction surface 75b of the yoke 75, the cam force received by the cam member 72 is The armature 73 acts almost uniformly on the inner peripheral friction surface 73a and the outer peripheral friction surface 73b.

[Third Embodiment]
FIG. 7 shows a schematic configuration of the electromagnetic clutch 12 according to the third embodiment of the present invention. In the second embodiment, the relative rotation between the armature 73 and the cam member 72 is restricted by spline fitting. However, in the electromagnetic clutch 12 according to the present embodiment, the armature 73A and the cam are fixed by a pin 79 described later. Relative rotation with the member 72A is restricted. Since other components are common to the electromagnetic clutch 11 according to the second embodiment, the same reference numerals as those in FIG.

  The cam member 72 </ b> A is an annular member made of a metal material such as carbon steel, is subjected to hardening treatment such as quenching and tempering and gas soft nitriding, and is externally fitted to the cylindrical portion 80 of the rotating member 8.

  The cam member 72A includes a cam portion 721A having a cam groove 72b formed on a surface facing the cam groove 81a formed in the flange portion 81 of the rotating member 8, and a press provided on the outer peripheral side of the cam portion 721A. The part 722A is integrally formed. The pressing portion 722A has an annular portion 723A provided on the outer peripheral side of the cam portion 721A, and a flange portion 724A formed so as to project from the end portion on the outer peripheral side of the annular portion 723A toward the armature 73A in the axial direction. And the pressing surface 724b which presses the armature 73A is formed in the axial direction front-end | tip part of the collar part 724A.

  The pressing portion 722A is provided with an axial hole 724c formed in the axial direction from the pressing surface 724b, and a pin 79 is press-fitted and fixed to the axial hole 724c.

  The armature 73A is a plate-like member made of a magnetic material such as carbon steel (for example, S35C, S10C), and is molded in an annular shape with a through hole 731A formed in the center. On the surface of the armature 73A facing the yoke 75, an inner peripheral friction surface 73f that frictionally engages with the inner peripheral friction surface 75a of the yoke 75, and an outer peripheral friction that frictionally engages with the outer peripheral friction surface 75b of the yoke 75. A surface 73g is formed.

  A through hole 73h penetrating in the axial direction is provided between the inner peripheral friction surface 73f and the outer peripheral friction surface 73g of the armature 73A, and the through hole 73h is fixed to the axial hole 724c of the cam member 72A. A pin 79 is inserted. With this configuration, the relative rotation between the armature 73A and the cam member 72A is restricted, and the armature 73A can move in the axial direction with respect to the cam member 72A.

  Further, the armature 73A is urged in the axial direction toward the cam member 72A by a disc spring 76 in contact with the inner peripheral end portion thereof.

A radius r ₁ from the rotation axis O ₂ of the radial center 724 d of the pressing surface 724 b of the cam member 72 A is larger than a radius r ₂ from the rotation axis O ₂ of the radial center 750 a of the annular recess 750 of the yoke 75. That is, the cam member 72 </ b> A presses the armature 73 </ b> A at a position that is biased toward the outer peripheral friction surface 75 b rather than the inner peripheral friction surface 75 a of the yoke 75. Thus, the cam force received by the cam member 72A acts more strongly between the outer peripheral friction surface 75b and the outer peripheral friction surface 75b than between the inner peripheral friction surface 75a and the inner peripheral friction surface 73f.

(Effect of the third embodiment)
According to the third embodiment of the present invention described above, there are the same effects as the effects of the second embodiment. Further, since the cam force received by the cam member 72A mainly acts between the outer peripheral friction surface 73g and the outer peripheral friction surface 75b, the friction torque between the armature 73A and the yoke 75 can be increased.

[Other embodiments]
As mentioned above, although the electromagnetic clutch of this invention was demonstrated based on said embodiment, this invention is not limited to said embodiment, It implements in a various aspect in the range which does not deviate from the summary. For example, the following modifications are possible.

(1) In each of the above embodiments, a spherical cam follower is interposed between the first cam member and the second cam member, or between the flange portion of the rotating member and the cam member. An inclined surface inclined with respect to the axial direction is formed between the first cam member and the second cam member or between the flange portion of the rotating member and the cam member, and the cam force is generated by sliding between the inclined surfaces. May be generated.

(2) In each of the above embodiments, the armature is frictionally engaged with the rear housing or the yoke when the electromagnetic coil is energized, and the frictional engagement is released by the biasing force of the disc spring when deenergized. On the contrary, the armature is frictionally engaged with other members by the biasing force of an elastic member such as a disc spring when the electromagnetic coil is not energized, and the frictional engagement is released by the magnetic force when the electromagnetic coil is energized. You may comprise.

(3) The position where the first cam member or the cam member presses the armature is not limited to that shown in the above embodiments. Even if the electromagnetic clutch is configured such that the first cam member or the cam member presses the region including the inner peripheral end of the armature, the bending of the first cam member or the cam member due to the cam force does not directly affect the armature. The effects of the present invention are exhibited.

(4) The structure for preventing the first cam member or the cam member and the armature from rotating is not limited to those shown in the above embodiments, and various rotation preventing structures can be applied.

(5) The surface treatment or heat treatment applied to the first cam member or the cam member and the armature is not limited to those shown in the above embodiments, and the surface treatment or heat treatment may not be performed.

(6) The first cam member or the cam member is not limited to directly pressing the armature, and may be configured to press the armature via another member.

(7) There are no particular restrictions on the use and application object of the electromagnetic clutch.

DESCRIPTION OF SYMBOLS 1 ... Driving force transmission device, 2 ... Housing, 3 ... Inner shaft, 3a ... End surface, 3b ... Hollow part, 3c ... Straight spline fitting part, 3d ... End surface, 3e ... Hollow part, 3f ... Wall part, 3g ... Straight Spline fitting part, 3h ... step part, 4 ... main clutch, 5 ... electromagnetic coil, 5a ... electric wire, 6 ... cam mechanism, 8 ... rotating member, 8a ... end, 9 ... casing, 9a ... recess, 10,11 12 ... Electromagnetic clutch, 21 ... Front housing, 21a ... Housing space, 21b ... Straight spline fitting part, 22 ... Rear housing, 22a ... Housing space, 22b ... Friction surface, 31 ... Snap ring, 41 ... Outer clutch plate, 41a ... Spline fitting portion, 42 ... Inner clutch plate, 42a ... Spline fitting portion, 42b ... Hole, 51 ... Yoke, 51a, 51b ... Air Cap, 51c ... Accommodating space, 51d ... Hole, 52 ... Seal bearing, 60 ... Armature, 60a ... Friction surface, 60b ... Pressed surface, 60c ... Side surface, 61 ... First cam member, 62 ... Second cam member, 63 ... cam followers, 64, 65 ... disc springs, 71 ... cam followers, 72, 72A ... cam members, 72a, 72b ... cam grooves, 73, 73A ... armatures, 73a ... inner peripheral friction surfaces, 73b ... outer peripheral friction surfaces, 73c ... pressed surface, 73d ... outer circumference circle, 73e ... inner circumference circle, 73f ... inner circumference friction surface, 73g ... outer circumference friction surface, 73h ... through hole, 74 ... electromagnetic coil, 75 ... yoke, 75a ... inner circumference side Friction surface, 75b ... outer peripheral side friction surface, 75c ... stepped portion, 76 ... disc spring, 77 ... ball bearing, 78 ... spacer, 79 ... pin, 80 ... cylindrical portion, 80a ... straight spline fitting portion, 80b ... Difference part, 81 ... collar part, 81a ... cam groove, 91 ... bolt, 101 ... four-wheel drive vehicle, 102 ... engine, 103 ... transaxle, 104 ... front axle shaft, 105 ... front wheel, 106 ... propeller shaft, 107 ... Differential carrier 108 ... Drive pinion shaft 109 ... Rear differential 110 ... Rear axle shaft 111 ... Rear wheel 112 ... Controller ... 200 Armature cam 201 ... Cam part 201a ... Cam groove 202 ... Pressing part 202a ... friction surface, 210 ... ball bearing, 220 ... needle bearing, 221 ... outer member, 222 ... intermediate member, 223 ... inner member, 600a ... end, 600b ... center, 601 ... through hole, 602 ... spline fitting part, 611 ... Cam portion, 611a ... Cam groove, 612 ... Sp Line fitting portion, 612a ... cam groove, 613 ... pressing portion, 614 ... annular portion, 615 ... collar portion, 615a ... pressing surface, 621 ... cam portion, 621a ... cam groove, 621a ... pressing surface, 622 ... spline fitting Part, 622a ... cam groove, 623 ... pressing part, 711 ... retainer, 721, 721A ... cam part, 722 ... spline fitting part, 722A, 723A ... annular part, 724 ... annular part, 724A ... collar part, 724b ... pressing part Surface, 724c ... axial hole, 724d ... radial center, 725 ... collar, 725a ... pressing surface, 731, 731A ... through hole, 732 ... spline fitting part, 750 ... annular recess, 750a ... radial center, 751 ... Snap ring, 771 ... Inner ring, 772 ... Outer ring, 773, 774 ... Snap ring, M, M ₂ ... Magnetic flux, O, O ₂ ... Rotating shaft, r1, r2 ... Radius

Claims (4)

An electromagnetic coil that generates magnetic force;
An armature that moves axially by the magnetic force;
A friction member that contacts the armature by axial movement of the armature;
A first cam member in which relative rotation with the armature is restricted;
A second cam member that generates a cam force that presses the armature toward the friction member on the first cam member by relative rotation with the first cam member;
With electromagnetic clutch. The armature is a ring with a through hole formed in the center,
2. The electromagnetic clutch according to claim 1, wherein the first cam member presses the armature on an outer peripheral side with respect to an inner peripheral side end portion of the armature.   The friction member is frictionally engaged with one side surface of the armature by a friction surface formed on an inner peripheral side and an outer peripheral side of an annular recess opened to the armature side, and the electromagnetic coil is accommodated in the annular recess. The electromagnetic clutch according to claim 1, wherein the electromagnetic clutch is a yoke.   The said 1st cam member produces | generates the maximum load which presses the other side surface of the said armature in the area | region of the radial direction between the inner peripheral side of the said annular recess of the said yoke, and the outer peripheral side friction surface. The electromagnetic clutch described.

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