JP2009138798A - Electromagnetic clutch and driving force transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic clutch and a driving force transmission device having the electromagnetic clutch, capable of accurately controlling transmission torque, by maintaining an excellent torque transmission characteristic over a long period by a driving force transmission member with a simple constitution. <P>SOLUTION: In the electromagnetic clutch, an opposed surface opposed to a bottom 15 of an armature 25 has a sticking surface 41 stuck with a frictional material 26 frictionally engaging with the bottom 15 and a magnetic flux passing surface 42 formed in closer vicinity to the bottom 15 than the sticking surface 41 and passing a magnetic flux of magnetic flux density higher than the sticking surface 41. The frictional material 26 is formed in the thickness capable of making lubricating oil flow between the bottom 15 and the magnetic flux passing surface 42, by maintaining a gap between the bottom 15 and the magnetic flux passing surface 42, with the frictional material 26 frictionally engaged with the bottom 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic clutch and a driving force transmission device including the electromagnetic clutch.

  Conventionally, a first rotating member having a cylindrical portion, a second rotating member coaxially disposed in the first rotating member, and a drive for transmitting torque between the first rotating member and the second rotating member. A force transmission member, an electromagnetic coil that frictionally engages both driving force transmission members by generating magnetic flux in a magnetic path passing through these driving force transmission members, and a predetermined filling rate in the first rotating member. There are so-called wet electromagnetic clutches with lubricating oil. For example, an electromagnetic clutch used in a driving force transmission device described in Patent Document 1 includes an armature attracted by an electromagnetic coil, and a magnetic path forming member interposed between the armature and the electromagnetic coil, and includes a driving force transmission member The outer clutch plate and the inner clutch plate are provided between the armature and the magnetic path forming member. Then, when the armature is attracted by energizing the electromagnetic coil, the outer clutch plate and the inner clutch plate are frictionally engaged, and torque is transmitted between the first rotating member and the second rotating member. It has become.

By the way, in the said patent document 1, the film thickness of the oil film formed between sliding contact surfaces is maintained appropriately, for example by forming a fine groove in the sliding contact surface of an inner clutch plate. Accordingly, the μ-V characteristic indicating the relationship between the sliding speed V between the sliding contact surfaces and the friction coefficient μ is defined as a high friction positive gradient in which the friction coefficient μ increases as the sliding speed V increases. Vibration (judder) caused by stick-slip with the outer clutch plate is prevented, and good torque transmission characteristics are secured. Further, in Patent Document 1, the inner clutch plate is subjected to surface treatment such as quenching, and a DLC film (diamond-like carbon film) is formed on the sliding contact surface of the outer clutch plate to thereby wear between the clutch plates. And a good torque transmission characteristic is maintained over a long period of time.
JP 2003-28218 A

  By the way, in Patent Document 1, it is necessary to form a fine groove on the sliding contact surface of the clutch plate in order to prevent the judder by making the μ-V characteristic a positive gradient. In addition, in order to suppress wear between the clutch plates, it is necessary to apply a surface treatment such as DLC film formation or quenching to each clutch plate. Therefore, there is a problem that the manufacturing cost of each clutch plate (driving force transmission member) increases due to these surface treatments. In addition, a fine groove or a DLC film, which is a nonmagnetic material, is formed on the sliding contact surface of each clutch plate, which causes a problem that the amount of magnetic flux between the clutch plates is reduced.

  Therefore, it is conceivable to attach a paper-based friction material to the sliding contact surface of the clutch plate. This is because the paper-based friction material can maintain the film thickness of the oil film formed between the sliding contact surfaces by allowing the lubricating oil to permeate between the fiber base materials and is softer than the clutch plate. Therefore, the wear of the clutch plate can be suppressed, and good torque transmission characteristics with excellent judder resistance can be ensured over a long period of time. However, since the friction material is made of a non-magnetic material, it is difficult for the magnetic flux to pass through, and the gap between the clutch plates becomes large because there is a limit to reducing the thickness. For this reason, a decrease in the amount of magnetic flux between the clutch plates becomes large, and the armature cannot be sufficiently attracted, resulting in a problem that the torque capacity cannot be secured. Such a problem is not limited to the case where the clutch plate is used as the driving force transmission member, and other members that rotate integrally with the first rotating member and members that rotate integrally with the second rotating member are driven force transmitting members. It also occurs in the same way when used as.

  Further, in a wet type electromagnetic clutch in which lubricating oil is interposed between the driving force transmission members, even when the driving force transmission members are not engaged, the engaging force based on the viscosity of the lubricating oil interposed therebetween. This causes a so-called drag torque, which causes a problem that the transmission torque cannot be accurately controlled.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to maintain a good torque transmission characteristic over a long period of time with a simple structure driving force transmission member and to accurately transmit the transmission torque. An electromagnetic clutch that can be controlled and a driving force transmission device including the electromagnetic clutch.

  In order to achieve the above object, the invention according to claim 1 is a first rotating member having a cylindrical portion, a shaft-shaped second rotating member rotatably and coaxially disposed in the first rotating member, and A first driving force transmission member provided so as to be integrally rotatable with any one of the first rotating member and the second rotating member; and any one of the first rotating member and the second rotating member; A second driving force transmission member provided so as to be integrally rotatable, and an electromagnetic coil that frictionally engages both driving force transmission members by generating a magnetic flux in a magnetic path passing through the first and second driving force transmission members; An electromagnetic clutch provided with lubricating oil accommodated in the first rotating member at a predetermined filling rate, wherein a facing surface of the first driving force transmitting member facing the second driving force transmitting member is A friction material that is frictionally engaged with the second driving force transmission member is attached. The magnetic flux passage surface is formed closer to the second driving force transmitting member than the sticking surface, and the magnetic flux through which the magnetic flux density is higher than the sticking surface passes. And the friction material maintains a gap between the second driving force transmission member and the magnetic flux passage surface in a state where the friction material and the second driving force transmission member are frictionally engaged with each other. The gist of the present invention is that the lubricating oil is formed to a thickness allowing flow between the second driving force transmission member and the magnetic flux passage surface.

  According to the said structure, the opposing surface which opposes the said 2nd driving force transmission member of a 1st driving force transmission member is a 2nd driving force transmission rather than the sticking surface to which a friction material is stuck, and this sticking surface. A magnetic flux passage surface that is formed close to the member and through which a magnetic flux having a higher magnetic flux density than the sticking surface passes. For this reason, the gap between the magnetic flux passage surface and the second driving force transmission member can be made smaller than the thickness of the friction material, and the decrease in the amount of magnetic flux between the driving force transmission members is suppressed, and the armature is sufficiently It becomes possible to suck. Therefore, it is possible to frictionally engage the friction material and the driving force transmission member while ensuring the torque capacity, and a good torque can be obtained over a long period of time with a simple configuration of the driving force transmission member that does not require surface treatment. Transfer characteristics are maintained. In addition, since it is not necessary to perform surface treatment such as the formation of DLC film and fine grooves on each driving force transmission member, the manufacturing cost of the driving force transmission member can be reduced, and the decrease in the amount of magnetic flux accompanying the surface treatment can be prevented. Is done.

  Further, the friction material maintains a gap between the magnetic flux passage surface and the second driving force transmission member in a state where the first and second driving force transmission members are frictionally engaged, and the lubricating oil is used for the magnetic flux passage surface and the second driving force. It is formed in a thickness that allows flow between the transmission member. Therefore, the first driving force transmission member and the second driving force transmission member are separated from each other by the dynamic pressure of the lubricating oil, the drag torque is reduced, and the transmission torque is accurately controlled.

  According to a second aspect of the present invention, in the electromagnetic clutch according to the first aspect, the first driving force transmitting member can rotate integrally with any one of the first rotating member and the second rotating member. And the second driving force transmitting member is rotatable integrally with any one of the first rotating member and the second rotating member, and the armature and the armature are attached so as to be movable in the axial direction. The gist is that the magnetic path forming member is interposed between the electromagnetic coil and the magnetic coil.

  According to the above configuration, since the armature and the magnetic path forming member are directly frictionally engaged, it is not necessary to use a clutch plate as a driving force transmission member, and the number of parts is reduced. In addition, the magnetic path is shorter than when the clutch plate is provided between the armature and the magnetic path forming member, and the magnetic efficiency that passes through the clutch plate without passing through the armature and returns to the electromagnetic coil side is eliminated. Is improved.

  According to a third aspect of the present invention, in the electromagnetic clutch according to the first or second aspect, the magnetic flux passing surface is radially continuous from the radially inner end to the radially outer end of the first driving force transmission member. The gist is that it was formed.

  According to the above configuration, when the electromagnetic clutch rotates, the lubricating oil tends to flow from the radially inner side to the radially outer side of the first and second driving force transmission members by centrifugal force. The first driving force transmission member and the second driving force transmission member can be separated from each other, and the drag torque can be further reduced.

The gist of the invention described in claim 4 is the electromagnetic clutch according to any one of claims 1 to 3, wherein the friction material contains a soft magnetic material.
According to the above configuration, since the friction material contains the soft magnetic material, the magnetic permeability of the friction material is increased. Therefore, a decrease in the amount of magnetic flux between the driving force transmission members is further suppressed, and the armature is more sufficiently provided. It becomes possible to suck. The soft magnetic material refers to a magnetic material having a small coercive force and a high magnetic permeability.

  According to a fifth aspect of the present invention, there is provided a first rotating member having a cylindrical portion, a second rotating member coaxially disposed in the first rotating member, the first rotating member, and the second rotating member. A main clutch that transmits torque between the main clutch, an electromagnetic clutch juxtaposed in the axial direction of the main clutch, and the first clutch that is provided between the main clutch and the electromagnetic clutch and is transmitted via the electromagnetic clutch. A cam mechanism that presses the main clutch by converting a torque based on a rotational difference between the one rotating member and the second rotating member into an axial pressing force and moving the cam member in the axial direction; and the first rotating member And a lubricating oil contained at a predetermined filling rate, wherein the electromagnetic clutch is provided so as to be integrally rotatable with any one of the first rotating member and the second rotating member. Force transmission part A second driving force transmission member provided so as to be integrally rotatable with any one of the first rotating member and the second rotating member, and a magnetic path passing through the first and second driving force transmission members A driving force transmission device including an electromagnetic coil that frictionally engages both driving force transmission members by generating a magnetic flux in the first driving force transmission member opposite to the second driving force transmission member. The opposing surface is formed by adhering a friction material that frictionally engages with the second driving force transmission member, and being closer to the second driving force transmission member than the adhesion surface. A magnetic flux passage surface through which a magnetic flux having a higher magnetic flux density than the contact surface passes, and the friction material is in the state in which the friction material and the second driving force transmission member are frictionally engaged with each other. A gap between the force transmission member and the magnetic flux passage surface is maintained, and the lubricating oil is Wherein the driving force transmitting member is summarized in that formed in the thickness of the flowable between the magnetic flux passing surface.

  According to the above configuration, the friction material and the driving force transmission member can be frictionally engaged while securing the torque capacity, and the driving force transmission member with a simple configuration that does not require surface treatment can be used for a long period of time. And good torque transmission characteristics are maintained. Further, the first driving force transmission member and the second driving force transmission member are separated from each other by the dynamic pressure of the lubricating oil, the drag torque is reduced, and the transmission torque is accurately controlled.

  According to the present invention, an electromagnetic clutch capable of maintaining good torque transmission characteristics over a long period of time with a driving force transmission member having a simple configuration and capable of accurately controlling transmission torque, and a driving force including the electromagnetic clutch. A transmission device can be provided.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the electromagnetic clutch 11 includes a bottomed cylindrical outer housing 12 and a shaft-like inner shaft 13 that is coaxially arranged rotatably in a cylinder of the outer housing 12. The outer housing 12 is formed integrally with a cylindrical portion 14 as a first rotating member formed in a cylindrical shape and an inner shaft 13 side (left side in the figure) of the cylindrical portion 14 and is formed in an annular shape. It is comprised from the bottom part 15 as a 2nd driving force transmission member and a magnetic path formation member. A stainless annular member 16, which is a nonmagnetic material, is embedded in the radially intermediate portion of the bottom portion 15. An end housing 18 that closes the open end 17 of the cylindrical portion 14 is fixed to the outer housing 12. A flange portion 19 formed in a disk shape of the end housing 18 is screwed to the inner periphery of the opening end 17, and the flange portion 19 has a radial center in the opposite side of the outer housing 12 (in FIG. 1, A shaft-shaped shaft portion 20 protruding rightward) is formed. The inner shaft 13 as the second rotating member is rotatably supported by a ball bearing 21 provided at the inner periphery of the bottom portion 15 and a tapered roller bearing 22 provided at the center of the flange portion 19. The cylinder of the outer housing 12 is sealed by seal members 23 and 24 provided between the inner periphery of the bottom portion 15 and the inner shaft 13 and the fitting portion between the open end 17 and the end housing 18. Lubricating oil is contained in the cylinder. In the present embodiment, the inner shaft 13 is connected to an input shaft (not shown) connected to the drive source, and the shaft portion 20 is connected to the output shaft.

  Inside the cylindrical portion 14, an armature 25 as a first driving force transmission member formed in an annular shape is spline-fitted so as to be movable in the axial direction and integrally rotatable with the inner shaft 13. In the present embodiment, the armature 25 is provided with a friction material 26. In FIG. 1, the thickness of the friction material 26 is exaggerated for convenience of explanation. The friction material 26 is configured to frictionally engage with the bottom portion 15.

  Further, on the base end side (the left side in FIG. 1) of the inner shaft 13, a support member 29 and a yoke 30 screwed to the support member 29 through ball bearings 27 and 28 can rotate relative to the inner shaft 13. It is supported by. Then, the electromagnetic coil 31 surrounded by the yoke 30 is juxtaposed with the support member 29 in the axial direction of the armature 25 with the bottom 15 interposed therebetween. The support member 29 is provided with a power line 32 that is connected to the outside and supplies power to the electromagnetic coil 31.

Next, the structure of the armature 25 (driving force transmission member) will be described.
FIG. 2 shows a facing surface that faces the bottom 15 of the armature 25. An opposing surface of the armature 25 is formed with an adhesive surface 41 to which the friction material 26 that frictionally engages with the bottom portion 15 is attached, and closer to the bottom portion 15 than the adhesive surface 41. Has a magnetic flux passage surface 42 through which a magnetic flux having a high magnetic flux density passes. The friction material 26 maintains a gap between the bottom portion 15 and the magnetic flux passage surface 42 in a state where the friction material 26 and the bottom portion 15 are frictionally engaged, and lubricates the lubricant between the bottom portion 15 and the magnetic flux passage surface 42. It is formed to a thickness that allows fluid flow. In FIG. 2, the friction material 26 is hatched for convenience of explanation.

  More specifically, a plurality (8 in the present embodiment) of the sticking surfaces 41 are formed radially from the radially inner side to the radially outer side of the armature 25, and the magnetic flux passing surface 42 is radially inward of the armature 25. A plurality (in this embodiment, eight) are formed radially from the end to the radially outer end. In this embodiment, the sticking surface 41 and the magnetic flux passage surface 42 are formed at equal intervals along the circumferential direction. Then, the friction material 26 having a thickness larger than the axial depth of the adhesion surface 41 and having substantially the same shape as that of the adhesion surface 41 is adhered to the adhesion surface 41. The gap between the contact surface and the magnetic flux passing surface 42 is formed to have a predetermined value. The predetermined value refers to a gap in which the gap between the magnetic flux passage surface 42 and the bottom portion 15 is maintained during friction engagement in consideration of wear of the friction material, crushing allowance during friction engagement, and the like. Then, it is about 20 μm to 200 μm. Further, the outer housing 12 and the armature 25 are made of, for example, low carbon steel (S10C or the like), and the bottom 15 and the armature 25 are not subjected to surface treatment such as formation of a DLC film or a fine groove.

  In this embodiment, the friction material 26 is made of a paper-based wet friction material, and contains a soft magnetic material (a magnetic material characterized by a low coercive force and a high magnetic permeability). The friction material 26 is made by making a paper from a fiber base material such as wood pulp or aramid fiber, a friction modifier such as cashew dust, a filler such as calcium carbonate or diatomaceous earth filler, and a soft magnetic material. The paper body is impregnated with a resin binder made of a thermosetting resin, and then heat-cured by thermoforming. Further, as the soft magnetic material, for example, permalloy (iron-nickel alloy), pure iron or the like is used, and the soft magnetic material is formed into a powdery body or a needle-like body and contained in the friction material 26, for example. Further, the friction material 26 is formed so that the friction coefficient between the friction material 26 and the bottom 15 is larger than the friction coefficient between the low carbon steels on which the DLC film or the like is formed.

  In addition, since the friction material 26 can maintain appropriately the film thickness of the oil film formed between sliding contact surfaces because the lubricating oil permeates between the fiber base materials, the sliding speed between the armature 25 and the bottom portion 15 is maintained. The μ-V characteristic indicating the relationship between V and the friction coefficient μ is a high frictional positive gradient. As a result, vibration (judder) of the drive system caused by stick-slip between the armature 25 and the bottom portion 15 (behavior in which the transition from the static friction state to the dynamic friction state and vice versa) is suppressed. ing. Further, since the friction material 26 is a softer material than the outer housing 12 (low carbon steel), wear of the bottom portion 15 is suppressed. Accordingly, the friction material 26 is interposed between the armature 25 and the bottom portion 15 so as to be frictionally engaged, thereby ensuring a good torque transmission characteristic that is excellent in judder resistance over a long period of time.

  When a current is supplied to the electromagnetic coil 31, the annular member 16 prevents the magnetic flux from being short-circuited in the bottom portion 15, and circulates in the electromagnetic clutch 11 as indicated by a one-dot chain line as shown in FIG. 1. A magnetic path M1 is generated. That is, the magnetic path M <b> 1 that circulates through the yoke 30, the bottom portion 15, the armature 25, the bottom portion 15, and the yoke 30 is formed. Then, the armature 25 is attracted by the magnetic force of the electromagnetic coil 31, the bottom portion 15 and the armature 25 are frictionally engaged via the friction material 26, and the outer housing 12 and the inner shaft 13 are coupled so as to transmit torque. It has become.

  At this time, as shown in FIG. 3, the magnetic flux flowing into the armature 25 from the bottom portion 15 flows into the armature 25 via the gap G or the friction material 26 between the magnetic flux passage surface 42 and the bottom portion 15. In FIG. 3, the flow of magnetic flux is indicated by a white arrow, and the amount of magnetic flux is indicated by the size of the white arrow. Since the friction material 26 is adhered to the adhesion surface 41, the gap G becomes smaller than the thickness of the friction material 26, and a decrease in the amount of magnetic flux between the magnetic flux passage surface 42 and the bottom portion 15 is suppressed. Note that the magnetic flux flowing into the bottom 15 from the armature 25 is similarly suppressed from decreasing in the amount of magnetic flux. Therefore, the armature 25 is sufficiently attracted by the magnetic force generated by the electromagnetic coil 31, and the friction material 26 and the armature 25 are frictionally engaged while securing the torque capacity. Further, the magnetic path is shortened as compared with the case where the clutch plate is provided between the armature 25 and the bottom portion 15, and the magnetic flux passing through the clutch plate without passing through the armature 25 and returning to the electromagnetic coil 31 side is eliminated. Efficiency is improved.

  In addition, the gap between the magnetic flux passage surface 42 and the bottom portion 15 is maintained during the frictional engagement between the bottom portion 15 and the armature 25, and the lubricating oil can flow between the magnetic flux passage surface 42 and the bottom portion 15, The bottom 15 and the armature 25 can be separated from each other by the dynamic pressure of the lubricating oil, and the drag torque can be reduced. In the present embodiment, a plurality of magnetic flux passage surfaces 42 are formed radially from the radially inner side to the radially outer side of the armature 25, so that when the electromagnetic clutch 11 rotates, the lubricating oil is separated from the armature 25 and the armature 25 by centrifugal force. It becomes easy to flow from the radially inner side of the bottom portion 15 toward the radially outer side. Therefore, it is possible to efficiently separate the bottom portion 15 and the armature 25, and the drag torque can be further reduced.

  Further, since the magnetic material is contained in the friction material 26, the magnetic permeability of the friction material 26 is increased, so that a decrease in the amount of magnetic flux flowing into the armature 25 through the friction material 26 is suppressed. Therefore, a decrease in the amount of magnetic flux between the bottom 15 and the armature 25 is further suppressed.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The facing surface facing the bottom 15 of the armature 25 is formed closer to the bottom 15 than the pasting surface 41 and the pasting surface 41 to which the friction material 26 frictionally engaging the bottom 15 is pasted. And a magnetic flux passage surface 42 through which a magnetic flux having a higher magnetic flux density than the sticking surface 41 passes. The friction material 26 maintains a gap between the bottom portion 15 and the magnetic flux passage surface 42 in a state where the friction material 26 and the bottom portion 15 are frictionally engaged, and lubricates the lubricant between the bottom portion 15 and the magnetic flux passage surface 42. To a thickness allowing flow. Therefore, the gap G between the magnetic flux passage surface 42 and the bottom portion 15 can be made smaller than the thickness of the friction material 26, and a decrease in the amount of magnetic flux between the armature 25 and the bottom portion 15 is suppressed, and the armature 25 is Sufficient suction is possible. Therefore, the friction material 26 and the bottom portion 15 can be frictionally engaged while securing a torque capacity, and good torque transmission characteristics can be maintained over a long period of time with a simple configuration that does not require surface treatment. In addition, since it is not necessary to perform surface treatment such as formation of a DLC film and fine grooves on each clutch plate, the manufacturing cost of the outer housing 12 and the armature 25 can be reduced, and the amount of magnetic flux associated with the surface treatment is reduced. Can be prevented.

  In addition, since the lubricating oil can flow between the magnetic flux passage surface 42 and the bottom portion 15 in a state where the bottom portion 15 and the armature 25 are frictionally engaged, the bottom portion 15 and the armature 25 are separated by the dynamic pressure of the lubricating oil. Thus, drag torque can be reduced, and transmission torque can be controlled with high accuracy.

  (2) Since the armature 25 is used as the first driving force transmission member and the bottom portion 15 is used as the second driving force transmission member, it is not necessary to use a clutch plate as the driving force transmission member, and the number of parts can be reduced. Further, the magnetic path is shortened as compared with the case where the clutch plate is provided between the armature 25 and the bottom portion 15, and the magnetic flux passing through the clutch plate without passing through the armature 25 and returning to the electromagnetic coil 31 side is eliminated. Efficiency can be improved.

  (3) The magnetic flux passage surface 42 is formed in a radial pattern that continues from the radially inner end of the armature 25 to the radially outer end. Therefore, when the electromagnetic clutch 11 rotates, the lubricating oil easily flows from the radially inner side to the radially outer side of the armature 25 and the bottom portion 15 by centrifugal force, and efficiently separates the armature 25 and the bottom portion 15. The drag torque can be further reduced.

  (4) Since a soft magnetic material is contained in the friction material 26, the magnetic permeability of the friction material 26 is increased, a decrease in the amount of magnetic flux between the armature 25 and the bottom portion 15 is further suppressed, and the armature 25 is made more fully. Can be aspirated.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 4, the driving force transmission device 51 is disposed coaxially with a bottomed cylindrical outer housing 53 rotatably accommodated in a coupling case 52 and within the outer housing 53 in a rotatable manner. And an axial inner shaft 54.

  The outer housing 53 as the first rotating member is rotatably supported by a ball bearing 55 with its bottom 53a (left side in the figure) exposed to the outside of the coupling case 52, and its open end 53b. A ring-shaped rear housing 56 is fitted into the housing. The inner shaft 54 as the second rotating member is rotatably supported by a needle bearing 57 provided on the inner periphery of the rear housing 56 and a ball bearing 58 provided in a cylinder of the outer housing 53. The cylinder of the outer housing 53 is formed by a fitting portion between the outer housing 53 and the rear housing 56 and seal members 59 and 60 provided between the inner periphery of the rear housing 56 and the outer periphery of the inner shaft 54. Sealed and lubricating oil is contained in the cylinder.

  The bottom 53a of the outer housing 53 is connected by a bolt 61 to a flange (not shown) provided on a propeller shaft (not shown). As a result, the outer housing 53 rotates in response to the input of driving force generated by an engine (not shown) as a driving source. A connecting portion (spline fitting portion) 62 (not shown) with a rear differential (not shown) is formed on the inner periphery of the shaft end (right side in the drawing) of the inner shaft 54 that is supported by the needle bearing 57. Yes. That is, when the vehicle is mounted on the driving force transmission device 51, the outer housing 53 is connected to the front wheel side that is the main driving wheel, and the inner shaft 54 is connected to the rear wheel side that is the auxiliary driving wheel.

  Further, a main clutch 63 capable of connecting the outer housing 53 and the inner shaft 54 so as to transmit torque is provided in the cylinder of the outer housing 53, and an electromagnetic clutch is provided in the axial direction of the main clutch 63 and on the rear housing 56 side. 64 are juxtaposed. A cam mechanism 65 is provided between the main clutch 63 and the electromagnetic clutch 64.

  The main clutch 63 employs a multi-plate friction clutch in which a plurality of outer clutch plates 66 and inner clutch plates 67 that are movably provided in the axial direction are alternately arranged. Specifically, each outer clutch plate 66 is spline-fitted to the inner periphery of the outer housing 53 and each inner clutch plate 67 is spline-fitted to the outer periphery of the inner shaft 54, so that each outer clutch plate 66 can move in the axial direction and has a corresponding outer The housing 53 or the inner shaft 54 is provided so as to be rotatable together. The main clutch 63 connects the outer housing 53 and the inner shaft 54 so that torque can be transmitted by the outer clutch plates 66 and the inner clutch plates 67 being pressed in the axial direction and frictionally engaged with each other. It has become.

  The cam mechanism 65 is provided with a first cam 68 rotatably supported on the inner shaft 54 and a spline fit on the outer periphery of the inner shaft 54 so that the cam mechanism 65 can rotate integrally with the inner shaft 54 and move in the axial direction. The second cam 69 and a cam follower 70 interposed between the first cam 68 and the second cam 69 are provided. Both the first cam 68 and the second cam 69 as a cam member are formed in an annular shape, and the first cam 68 is disposed on the rear housing 56 side, and the second cam 69 is disposed on the main clutch 63 side. The first cam 68 is in contact with a needle bearing 71 provided between the first housing 68 and the rear housing 56, and is supported so as to be relatively rotatable with a certain distance from the rear housing 56. The second cam 69 is spline-fitted to the electromagnetic clutch 64 side of the spline groove of the inner shaft 54 to which the inner clutch plate 67 is fitted.

  A plurality of V-shaped grooves inclined with respect to the circumferential direction are formed on the opposing surfaces of the first cam 68 and the second cam 69 so as to oppose each other, and the cam follower 70 is provided with each of the opposing V-shaped grooves. It is clamped by the first cam 68 and the second cam 69 in a state of being disposed inside. In the cam mechanism 65, when the first cam 68 and the second cam 69 rotate relative to each other, the first cam 68 and the second cam 69 are separated from each other, that is, the first cam 68 is on the main clutch 63 side. The main clutch 63 is pressed in the axial direction.

  The electromagnetic clutch 64 includes a rear housing 56 as a second driving force transmission member and a magnetic path forming member, and an armature 73 as a first driving force transmission member that is attracted by the magnetic force generated by the electromagnetic coil 72. Specifically, the rear housing 56 is formed with an annular groove 74 that opens to the outside of the outer housing 53 (on the side opposite to the outer housing 53, the right side in FIG. 4). The armature 73 is surrounded and accommodated therein, and is arranged in parallel with the rear housing 56 interposed in the axial direction of the armature 73. The rear housing 56 is provided with a cylindrical portion 56a extending axially from the inner peripheral portion thereof to the side opposite to the outer housing 53. The yoke 75 is supported by a ball bearing 76 provided on the cylindrical portion 56a. 56 (and the outer housing 53) are rotatably supported. Further, a stainless steel annular member 77 (see FIG. 5), which is a non-magnetic material, is embedded in a radially intermediate portion of the rear housing 56.

  The armature 73 formed in an annular shape is provided so as to be slidable in the axial direction and rotatable integrally with the first cam 68 by being spline fitted to the outer periphery of the first cam 68. As shown in FIG. 5, in this embodiment, the armature 73 is provided with a friction material 78. 4 and 5, the thickness of the friction material 78 is exaggerated for convenience of explanation. The electromagnetic clutch 64 is connected to the outer housing 53 and the first cam 68 so that torque can be transmitted when the armature 73 is attracted to the electromagnetic coil 72 and the friction material 78 and the rear housing 56 are frictionally engaged. It has become.

  That is, the first cam 68 having the cam follower 70 sandwiched between the second cam 69 and the second cam 69, that is, the inner shaft 54, is integrally rotated when the electromagnetic clutch 64 is not operated. A rotation difference corresponding to the rotation difference between the outer housing 53 and the inner shaft 54 is generated between the housing 53 and the first cam 68. The electromagnetic clutch 64 is connected to the outer housing 53 and the first cam 68 so that torque can be transmitted by the operation thereof, so that the torque based on the rotational difference between the outer housing 53 and the inner shaft 54 (first cam 68). Is transmitted to the cam mechanism 65.

  That is, in the driving force transmission device 51, the torque based on the rotational difference between the outer housing 53 and the inner shaft 54 is transmitted to the cam mechanism 65 by the operation of the electromagnetic clutch 64, and the cam mechanism 65 generates the second cam generated by the torque. Based on the rotation difference between the first cam 68 and the first cam 68, the second cam 69 is moved to the axial main clutch 63 side. That is, the cam mechanism 65 converts the torque based on the rotational difference between the outer housing 53 and the inner shaft 54 transmitted through the electromagnetic clutch 64 into axial thrust and amplifies it. When the second cam 69 presses the main clutch 63, the main clutch 63 is operated, that is, the outer housing 53 and the inner shaft 54 are connected so as to transmit torque. As described above, the driving force transmission device 51 can control the operation of the electromagnetic clutch 64 through the power supply to the electromagnetic coil 72. The operation of the main clutch 63, that is, the torque that can be transmitted between the outer housing 53 and the inner shaft 54 can be freely controlled through the operation of the electromagnetic clutch 64.

  In the present embodiment, the armature 73 and the friction material 78 are formed in the same manner as in the first embodiment. When a current is supplied to the electromagnetic coil 72, the annular member 77 prevents the magnetic flux from being short-circuited in the rear housing 56, and the driving force transmission device 51 has a magnetic path M2 that circulates as shown by a one-dot chain line. appear. That is, the magnetic path M2 that circulates through the yoke 75, the rear housing 56, the armature 73, the rear housing 56, and the yoke 75 is formed. At this time, similarly to the first embodiment, the armature 73 and the rear housing 56 are frictionally engaged via the friction material 78 while ensuring the torque capacity.

As mentioned above, according to this embodiment, there exists an effect similar to the effect described in 1st Embodiment.
In addition, you may implement each said embodiment in the following aspects.
In each of the above embodiments, the magnetic flux passage surface 42 is formed in a radial pattern that continues from the radially inner end of the armatures 25 and 73 to the radially outer end. However, the present invention is not limited to this. For example, as shown in FIG. 6A, the sticking surface 91 is formed in a spiral shape, and the magnetic flux passage surface 92 is extended from the radially inner end of the armatures 25 and 73 to the radially outer end. Alternatively, the friction material 93 may be attached to the attaching surface 91. Further, the magnetic flux passing surface may not be continuously formed from the radially inner end to the radially outer end of the armatures 25 and 73. For example, as shown in FIG. The passage surface 95 may be formed so as to alternate between the radially outer side and the radially inner side, and the friction material 96 may be attached to the attaching surface 94. Further, the magnetic flux passing surface may not be connected to the radially inner end and the radially outer end of the armatures 25 and 73. For example, as shown in FIG. May be formed concentrically, and the friction material 99 may be attached to the attachment surface 97. 6A to 6C, the friction materials 93, 96, and 99 are hatched for convenience of explanation.

  In each of the above embodiments, the armatures 25 and 73 are used as the first driving force transmission member, and the magnetic flux passage surface 42 and the sticking surface 41 are formed on the armatures 25 and 73. However, the present invention is not limited thereto, and the bottom 15 and the rear housing 56 As a first driving force transmission member, a magnetic flux passage surface and a sticking surface may be formed on the bottom portion 15 or the rear housing 56.

  In each of the above embodiments, an oil groove that guides the lubricating oil from the radially inner ends of the armatures 25 and 73 to the radially outer ends of the magnetic flux passage surface 42 may be formed. The lubricating oil is guided from the radially inner end of the bottom 15 and the rear housing 56 to the radially outer end of the bottom 15 facing the armature 25 and the facing surface of the rear housing 56 facing the armature 73. An oil groove may be formed. By doing so, the lubricating oil introduced between the armatures 25 and 73 and the bottom 15 or the rear housing 56 can be increased, and the drag torque can be further reduced.

In each of the above embodiments, the soft magnetic material is included in the friction materials 26 and 78, but the soft magnetic material may not be included.
In the first embodiment, the electromagnetic coil 31 is juxtaposed with the bottom portion 15 interposed in the axial direction of the armature 25. In the second embodiment, the electromagnetic coil 72 is interposed in the axial direction of the armature 73. And juxtaposed. However, the present invention is not limited to this, and if the armature 25 and the bottom portion 15 are frictionally engaged by the magnetic flux generated by the electromagnetic coil 31, the electromagnetic coil 31 may not be juxtaposed in the axial direction of the armature 25. 72 need not be juxtaposed in the axial direction of the armature 73.

  In the first embodiment, the bottom 15 rotates integrally with the cylindrical portion 14 and the armature 25 rotates integrally with the inner shaft 13. However, the present invention is not limited to this, and the bottom 15 rotates integrally with the inner shaft 13. At the same time, the armature 25 may rotate integrally with the cylindrical portion 14. In the second embodiment, the rear housing 56 rotates integrally with the outer housing 53 and the armature 73 rotates integrally with the inner shaft 54. However, the present invention is not limited thereto, and the rear housing 56 and the inner shaft 54 rotate. The armature 73 may rotate integrally with the outer housing 53 while rotating integrally.

  In the first embodiment, the armature 25 is used as the first driving force transmission member, and the bottom 15 is used as the second driving force transmission member. In the second embodiment, the armature 73 is used as the first driving force transmission member, and the rear housing 56 is used as the second driving force transmission member. However, the present invention is not limited to this, and a plurality of outer clutch plates and inner clutch plates arranged between the armature and the magnetic path forming member are used as the first and second driving force transmission members, and these outer clutch plates and inner clutches are used. A magnetic flux passage surface and a sticking surface may be formed on either one of the plates.

  In the second embodiment, the driving force transmission device 51 is provided on the driving force transmission path to the auxiliary driving wheel side in the four-wheel drive vehicle, and the torque transmitted to the auxiliary driving wheel is controlled. You may use for the differential apparatus etc. which have a function as a right-and-left driving force distribution apparatus.

  In the second embodiment, the electromagnetic clutch is used in the driving force transmission device that changes the driving force distribution between the front wheels and the rear wheels in the four-wheel drive vehicle. You may apply to the apparatus which uses this electromagnetic clutch.

Sectional drawing which shows schematic structure of an electromagnetic clutch. The top view of an armature. The schematic diagram which shows the flow of the magnetic flux between an armature and a bottom part. Sectional drawing which shows schematic structure of a driving force transmission apparatus. The partial expanded sectional view which shows schematic structure of a driving force transmission apparatus. (A)-(c) The top view of another armature.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11,64 ... Electromagnetic clutch, 13,54 ... Inner shaft, 14 ... Cylindrical part, 15 ... Bottom part, 25, 73 ... Armature, 26, 78, 93, 96, 99 ... Friction material, 31, 72 ... Electromagnetic coil, 41 91, 94, 97 ... sticking surface, 42, 92, 95, 98 ... magnetic flux passing surface, 51 ... driving force transmission device, 53 ... outer housing, 56 ... rear housing, 63 ... main clutch, 65 ... cam mechanism, 69 ... second cam, G ... gap, M1, M2 ... magnetic path.

Claims (5)

One of a first rotating member having a cylindrical portion, a shaft-shaped second rotating member coaxially disposed in the first rotating member, and the first rotating member and the second rotating member. A first driving force transmission member provided so as to be integrally rotatable with the first driving force transmission member, a second driving force transmission member provided so as to be integrally rotatable with any one of the first rotating member and the second rotating member, An electromagnetic coil that frictionally engages both driving force transmission members by generating magnetic flux in a magnetic path that passes through the first and second driving force transmission members, and is housed in the first rotating member at a predetermined filling rate. An electromagnetic clutch comprising lubricating oil,
The opposing surface of the first driving force transmission member that faces the second driving force transmission member includes an adhesion surface to which a friction material that frictionally engages with the second driving force transmission member is adhered, and the adhesion surface A magnetic flux passage surface that is formed closer to the second driving force transmission member and through which a magnetic flux having a higher magnetic flux density than the sticking surface passes,
The friction material maintains a gap between the second driving force transmission member and the magnetic flux passage surface in a state where the friction material and the second driving force transmission member are frictionally engaged with each other, and the lubricating oil is supplied to the friction material. 2. An electromagnetic clutch formed to a thickness allowing flow between the driving force transmission member and the magnetic flux passage surface. The first driving force transmission member is an armature that can be integrally rotated with any one of the first rotating member and the second rotating member, and can be moved in the axial direction.
The second driving force transmission member is a magnetic path forming member that can rotate integrally with one of the first rotating member and the second rotating member, and is interposed between the armature and the electromagnetic coil. The electromagnetic clutch according to claim 1, wherein the electromagnetic clutch is provided.   3. The electromagnetic clutch according to claim 1, wherein the magnetic flux passage surface is formed radially from the radially inner end to the radially outer end of the first driving force transmission member.   The electromagnetic clutch according to claim 1, wherein the friction material contains a soft magnetic material. A first rotating member having a cylindrical portion, a second rotating member coaxially disposed in the first rotating member, and a main that transmits torque between the first rotating member and the second rotating member. A clutch, an electromagnetic clutch juxtaposed in the axial direction of the main clutch, and the first rotating member and the second rotating member that are provided between the main clutch and the electromagnetic clutch and are transmitted via the electromagnetic clutch. And a cam mechanism that presses the main clutch by converting the torque based on the rotation difference to an axial pressing force and moving the cam member in the axial direction, and is accommodated in the first rotating member at a predetermined filling rate. A first driving force transmitting member provided so as to be integrally rotatable with any one of the first rotating member and the second rotating member, and the first rotation. Material By generating a magnetic flux in a second driving force transmission member provided so as to be integrally rotatable with either one of the second rotating members, and in a magnetic path passing through the first and second driving force transmission members, both are generated. A driving force transmission device composed of an electromagnetic coil that frictionally engages the driving force transmission member;
The opposing surface of the first driving force transmission member that faces the second driving force transmission member includes an adhesion surface to which a friction material that frictionally engages with the second driving force transmission member is adhered, and the adhesion surface A magnetic flux passage surface that is formed closer to the second driving force transmission member and through which a magnetic flux having a higher magnetic flux density than the sticking surface passes,
The friction material maintains a gap between the second driving force transmission member and the magnetic flux passage surface in a state where the friction material and the second driving force transmission member are frictionally engaged with each other, and the lubricating oil is supplied to the friction material. (2) A driving force transmission device having a thickness allowing flow between the driving force transmission member and the magnetic flux passage surface.

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