JP3574756B2 - Magnetic path forming member of electromagnetic clutch - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic path forming member of an electromagnetic clutch.
[0002]
[Prior art]
Generally, an electromagnetic clutch is provided with a magnetic path forming member as shown in Japanese Utility Model Registration No. 2525611. The magnetic path forming member supports an electromagnet and is located on one side of a friction clutch. , A magnetic path is formed through the friction clutch and an armature located on the other side of the friction clutch. Thus, the magnetic path forming member is composed of a main body made of a magnetic material, and a cylindrical body made of a non-magnetic material fitted and welded at a radially intermediate portion of the main body. Leakage of magnetic flux between other components of the clutch is prevented.
[0003]
In the magnetic path forming member, for example, the main body is formed of iron, which is a magnetic material, and the cylindrical body is formed of stainless steel, which is a non-magnetic material. Is welded to the friction clutch contact surface. Further, in the magnetic path forming member configured as described above, the friction clutch contact surface is subjected to finishing by cutting to increase the smoothness of the contact surface, and the friction surface between the contact surface and the clutch plate is increased. The air gap formed in the middle of the magnetic path is made as small as possible to improve the clutch characteristics of the friction clutch.
[0004]
[Problems to be solved by the invention]
However, in the magnetic path forming member, stainless steel (tubular body) is a hard-to-cut material compared to iron (main body), and the welded portion between the main body and cylindrical body is hardened by the action of heat during welding. Therefore, the machinability differs between the main body and the welded portion of the cylindrical body. For this reason, as shown in FIG. 3, for example, the welding portions 1a and 1b and the distal end portions of the cylindrical body 2 protrude from the friction clutch contact surfaces 3a1 and 3b1 of the inner and outer rings 3a and 3b constituting the main body to form a magnetic path. The smoothness of the friction clutch contact surface of the member is impaired.
[0005]
When the smoothness of the friction clutch contact surface of the magnetic path forming member is low, the air gap L formed in the middle of the magnetic path between the friction clutch contact surface and the clutch plate 4 becomes large, and the clutch characteristics of the friction clutch deteriorate. At the same time, oil in the friction clutch enters the large air gap L to form an oil film, and the responsiveness of the clutch decreases. In addition, due to the effect of the poor cutting of the friction clutch contact surface of the magnetic path forming member, the cutting state varies, and the clutch characteristics of each product vary.
[0006]
Therefore, an object of the present invention is to form the welding part between the main body and the cylindrical body in the magnetic path forming member with a special structure, thereby forming the welding part in the middle of the magnetic path between the friction clutch contact surface of the magnetic path forming member and the clutch plate. The purpose of the present invention is to reduce the influence of the air gap on clutch characteristics and clutch responsiveness of the electromagnetic clutch.
[0007]
[Means for Solving the Problems]
The present invention relates to a magnetic path forming member of an electromagnetic clutch, wherein the magnetic path forming member is located on one side of a friction clutch, and has an armature located on the other side of the friction clutch and the other side of the friction clutch with an electromagnet as a base point. It forms a magnetic path that passes.
[0008]
Thus, the magnetic path forming member has a body made of a magnetic material, is constituted by comprising the cylindrical body of a non-magnetic material which is welded fitted at an intermediate portion in the radial direction of the body, wherein The main body has an annular recess on the friction clutch contact surface, and a tip of the tubular body is welded in the recess, and the friction clutch side tip of the tubular body with respect to the body is the main body. The present invention is characterized in that it is located backward from the friction clutch contact surface. In the magnetic path forming member according to the present invention, it is possible to adopt a configuration in which the friction clutch abutment surface before SL body is subjected to finishing machining.
[0009]
[Action and Effect of the Invention]
In the magnetic path forming member according to the present invention, the welding portion at the friction clutch side end of the cylindrical body with respect to the main body is located retreating from the friction clutch abutting surface of the main body. Only the surface constitutes the friction clutch contact surface of the magnetic path forming member, and the tip of the cylindrical body does not contribute to the configuration of the friction clutch contact surface. When the main body and the cylindrical body are joined by welding, the distal end of the cylindrical body is welded in a recess provided on the friction clutch contact surface of the main body, so that the welding portion between the cylindrical body and the main body is welded. Like the distal end portion of the cylindrical body, it does not contribute to the configuration of the friction clutch contact surface.
[0010]
In this case, in order to increase the smoothness of the friction clutch abutting surface of the magnetic path forming member, even if the friction clutch abutting surface is subjected to finishing by cutting means, a welding portion between the distal end portion of the cylindrical body and the cylindrical body and the main body is formed. Is located in the recess, so that the smoothness of the friction clutch contact surface does not decrease due to these differences in machinability.
[0011]
Therefore, in the main body and the cylindrical body constituting the magnetic path forming member, the distal end portion of the cylindrical body and the welded portion between the cylindrical body and the main body contribute to the friction clutch contact surface and affect the smoothness of the friction clutch contact surface. Without affecting, the air gap formed in the middle of the magnetic path between the friction clutch contact surface of the magnetic path forming member and the clutch plate can be reduced, the clutch characteristics of the electromagnetic clutch by the air gap, and The formation of the oil film in the air gap can be suppressed, and the influence of the oil film in the air gap on the clutch characteristics and the clutch responsiveness of the electromagnetic clutch due to the oil film in the air gap can be suppressed.
[0012]
In addition, the clutch characteristics and clutch responsiveness of the electromagnetic clutch also affect the torque characteristics and torque responsiveness of the driving force transmission device that uses the electromagnetic clutch as an actuator, improving the torque characteristics and torque responsiveness of the driving force transmission device. And variations in torque characteristics among products can be suppressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows a driving force transmission device 10 using an electromagnetic clutch employing a magnetic path forming member according to the present invention as a pilot clutch mechanism. As shown in FIG. 4, the driving force transmission device 10 is mounted on a driving force transmission path to a rear wheel side in a four-wheel drive vehicle. In addition, since the main part of the driving force transmission device 10 has a substantially symmetrical configuration with respect to the axis, FIG. 1 shows a substantially half portion of the driving force transmission device 10 and omits the other approximately half portion. are doing.
[0014]
In the four-wheel drive vehicle, the transaxle 21 integrally includes a transmission, a transfer, and a front differential, and outputs the driving force of the engine 22 to both axle shafts 24a, 24a via the front differential 23 of the transaxle 21. To drive the left and right front wheels 24b, 24b, and output to the first propeller shaft 25 side. The first propeller shaft 25 is connected to the second propeller shaft 26 via the driving force transmission device 10, and when the first propeller shaft 25 and the second propeller shaft 26 are connected to transmit torque, the first propeller shaft 25 is driven. The force is transmitted to the rear differential 27 and output from the rear differential 27 to both axle shafts 28a to drive the left and right rear wheels 28b.
[0015]
The driving force transmission device 10 is disposed between the first propeller shaft 25 and the second propeller shaft 26. As shown in FIG. 1, the outer case 10a, the inner shaft 10b, the main clutch mechanism 10c, the pilot clutch A mechanism 10d and a cam mechanism 10e are provided. An electromagnetic clutch according to one example of the present invention is employed as a pilot clutch mechanism 10d.
[0016]
The outer case 10a constituting the driving force transmission device 10 is formed by a bottomed cylindrical housing 11a and a rear cover 11b fitted to the rear end opening of the housing 11a to cover the opening. The housing 11a is formed of an aluminum alloy which is a non-magnetic material. The rear cover 11b corresponds to the magnetic path forming member according to the present invention, and includes a cover body made of iron as a magnetic material and a cylindrical body made of stainless steel as a non-magnetic material. The cover body is equivalent to the inner ring 11b1 and the outer ring 11b2, and the tubular body 11b3 is welded in a state fitted between the inner and outer rings 11b1 and 11b2 of the cover body.
[0017]
The inner shaft 10b penetrates the center of the rear cover 11b in a liquid-tight manner and is coaxially inserted into the outer case 10a. The inner shaft 10b is rotatably supported by the housing 11a and the rear cover 11b in a state where the axial direction is restricted. Have been. The distal end of the second propeller shaft 26 is inserted into the inner shaft 10b, and is connected so as to be able to transmit torque. A first propeller shaft 25 is connected to a front end portion of the housing 11a constituting the outer case 10a so as to be able to transmit torque.
[0018]
The main clutch mechanism 10c is a wet multi-plate type friction clutch, has a number of clutch plates (inner clutch plate 12a, outer clutch plate 12b), and is disposed in the housing 11a. Each inner clutch plate 12a constituting the friction clutch is spline-fitted to the outer periphery of the inner shaft 10b and is assembled so as to be movable in the axial direction, and each outer clutch plate 12b is spline-fitted to the inner periphery of the housing 11a. And can be moved in the axial direction. The respective inner clutch plates 12a and the respective outer clutch plates 12b are alternately positioned, are in contact with each other and frictionally engage with each other, and are separated from each other to be in a free state.
[0019]
The pilot clutch mechanism 10d is an electromagnetic clutch, and includes a rear cover 11b as a magnetic path forming member, an electromagnet 13, a friction clutch 14, an armature 15, and a yoke 16. The electromagnet 13 has an annular shape, and is fitted to the annular recess 11c of the rear cover 11b while being fitted to the yoke 16. The yoke 16 is fixed to the vehicle body while being rotatably supported on the outer periphery of the rear end of the rear cover 11b.
[0020]
The friction clutch 14 is a wet-type, multi-plate friction clutch composed of a plurality of outer clutch plates 14a and inner plates 14b. Each outer clutch plate 14a is spline-fitted to the inner periphery of the housing 11a so as to be movable in the axial direction. The inner clutch plates 14b are assembled and spline-fitted to the outer periphery of a first cam member 17 constituting a cam mechanism 10e described later so as to be movable in the axial direction.
[0021]
The armature 15 has an annular shape, is spline-fitted to the inner periphery of the housing 11a, and is mounted so as to be movable in the axial direction.
[0022]
In the pilot clutch mechanism 10d having the above configuration, a magnetic path through which the magnetic flux circulating through the yoke 16, the rear cover 11b, the friction clutch 14, and the armature 15 is formed with the electromagnet 13 as a base point by energizing the electromagnetic coil of the electromagnet 13. .
[0023]
The energization of the electromagnetic coil of the electromagnet 13 is switched on and off by a switch operation, so that three drive modes described later can be selected. The switch is disposed near the driver's seat in the passenger compartment so that the driver can easily operate the switch. If the driving force transmission device 10 is configured to have only a second driving mode described later, the switch can be omitted.
[0024]
The cam mechanism 10e includes a first cam member 17, a second cam member 18, and a cam follower 19. The first cam member 17 is rotatably fitted to the outer periphery of the inner shaft 10b, and is rotatably supported by the rear cover 11b, and the inner clutch plate 14b of the friction clutch 14 is spline-fitted to the outer periphery. I have. The second cam member 18 is spline-fitted to the outer periphery of the inner shaft 10b and is assembled so as to be integrally rotatable, and is located opposite the rear side of the inner clutch plate 12a of the main clutch mechanism 10c. A ball-shaped cam follower 19 is interposed between the opposing cam grooves of the first cam member 17 and the second cam member 18.
[0025]
In the driving force transmission device 10 having such a configuration, when the electromagnetic coil of the electromagnet 13 constituting the pilot clutch mechanism 10d is in a non-energized state, no magnetic path is formed, and the friction clutch 14 is in an unengaged state. For this reason, the pilot clutch mechanism 10d is in a non-operating state, the first cam member 17 constituting the cam mechanism 10e can rotate integrally with the second cam member 18 via the cam follower 19, and the main clutch mechanism 10c Is inactive. For this reason, the vehicle constitutes a first drive mode that is a two-wheel drive.
[0026]
On the other hand, when the electromagnetic coil of the electromagnet 13 is energized, a magnetic path in which the magnetic flux circulates is formed in the pilot clutch mechanism 10 d starting from the electromagnet 13, and the electromagnet 13 attracts the armature 15. For this reason, the armature 15 presses the friction clutch 14 to cause frictional engagement, connects the first cam member 17 of the cam mechanism 10e to the outer case 10a side, and causes relative rotation between the arm member 15 and the second cam member 18. Let it. As a result, in the cam mechanism 10e, the cam follower 19 presses the two cam members 17, 18 in a direction away from each other.
[0027]
For this reason, the second cam member 18 is pressed toward the main clutch mechanism 10c to cause the main clutch mechanism 10c to frictionally engage in accordance with the frictional engagement force of the friction clutch 14, thereby transmitting torque between the outer case 10a and the inner shaft 10b. Occurs. Thereby, the vehicle constitutes a second drive mode in which the first propeller shaft 25 and the second propeller shaft 26 are four-wheel drive between the non-directly connected state and the directly connected state. In this drive mode, the driving force distribution ratio between the front and rear wheels can be controlled in a range of 100: 0 (two-wheel drive state) to 50:50 (direct connection state) according to the running state of the vehicle.
[0028]
When the current flowing through the electromagnetic coil of the electromagnet 13 is increased to a predetermined value, the attraction force of the electromagnet 13 to the armature 15 is increased, and the armature 15 is strongly attracted to increase the frictional engagement force of the friction clutch 14. Increase the relative rotation between members 17,18. As a result, the cam follower 19 increases the pressing force on the second cam member 18 to bring the main clutch mechanism 10c into the connected state. For this reason, the vehicle constitutes a third drive mode in which the first propeller shaft 25 and the second propeller shaft 26 are four-wheel drive in a directly connected state.
[0029]
Thus, in the rear cover 11b which is a magnetic path forming member of the pilot clutch mechanism 10d, the cylindrical body 11b3 axially penetrates the cover main body formed by the inner and outer rings 11b1 and 11b2, as shown in FIG. The distal end faces an annular recess 11e provided on the distal end face 11d of the cover body. The front end surface 11d of the cover body is a contact surface that comes into contact with the outer clutch plate 14a that constitutes the friction clutch 14. In the recess 11e provided on the front end surface 11d, the front end of the cylindrical body 11b3 connects the cover body. The inner and outer rings 11b1 and 11b2 are welded to each other. The two welded portions 11f exhibit annular projections slightly projecting toward the distal end, and are located within the recess 11e so as to retreat from the distal end surface 11d. In the rear cover 11b, the projection at the welding portion 11f is 5 μm to 30 μm, and the depth of the recess 11e is 30 μm or more. Finishing processing by cutting means is performed on the front end surface 11d of the cover main body, and its smoothness is enhanced.
[0030]
In the rear cover 11b configured as described above, the welding portion 11f of the distal end portion of the cylindrical body 11b3 with respect to the cover main body (both the inner and outer rings 11b1 and 11b2) is located retreated from the distal end surface 11d of the cover main body. Only the front end surface 11d constitutes the friction clutch contact surface of the rear cover 11b, and the front end portion of the cylindrical body 11b3 and the welded portion 11f between the cylindrical body 11b3 and the cover main body come into contact with the outer clutch plate 14a of the friction clutch 14. Does not participate in the composition of
[0031]
In this case, in order to increase the smoothness of the friction clutch contact surface of the rear cover 11b, even if the front end surface 11d of the cover main body is subjected to finish processing by cutting means, the front end of the cylindrical body 11b3 and the cylindrical body 11b3 and the cover main body may be formed. Since the welded portion 11f is located in the recess 11e, there is no possibility that the smoothness of the friction clutch contact surface of the rear cover 11b is reduced due to these differences in machinability.
[0032]
As described above, the welded portion 11f of the cover body (both the inner and outer rings 11b1 and 11b2) and the cylindrical body 11b3 constituting the rear cover 11b, which is the magnetic path forming member, contributes to the friction clutch contact surface and the friction clutch contact surface is smoothed. Since the air gap L does not affect the air gap L, the air gap L formed in the middle of the magnetic path between the friction clutch contact surface of the rear cover 11b and the outer clutch plate 14a is reduced. The formation of the oil film can be suppressed, and the effect of the air gap L on the clutch characteristics of the pilot clutch mechanism 10d and the effect of the oil film in the air gap L on the clutch responsiveness of the pilot clutch mechanism 10d can be suppressed.
[0033]
Therefore, the torque characteristics and torque responsiveness of the driving force transmission device 10 using the pilot clutch mechanism 10d as an actuator can be improved, and variations in the torque characteristics among products can be suppressed.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a driving force transmission device using an electromagnetic clutch employing a magnetic path forming member according to an example of the present invention as a pilot clutch mechanism.
FIG. 2 is an enlarged partial cross-sectional view of a welding portion of a rear cover as the magnetic path forming member.
FIG. 3 is an enlarged partial sectional view of a welding portion in a conventional rear cover.
FIG. 4 is a schematic configuration diagram of a four-wheel drive vehicle equipped with the driving force transmission device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Drive force transmission device, 10a ... Outer case, 10b ... Inner shout, 10c ... Main clutch mechanism, 10d ... Pilot clutch mechanism, 10e ... Cam mechanism, 11a ... Housing, 11b ... Rear cover, 11b1, 11b2 ... Inner / outer ring (cover) 11b3 cylindrical body, 11c concave part, 11d distal end face, 11e concave part, 11f welded part, 12a inner clutch plate, 12b outer clutch plate, 13 electromagnet, 14 friction clutch, 14a ... outer clutch plate, 14b ... inner clutch plate, 15 ... armature, 16 ... yoke, 17 ... first cam member, 18 ... second cam member, 19 ... cam follower, 21 ... transaxle, 22 ... engine, 23 ... front Differential, 24a ... axle shaft, 4b: front wheel, 25, 26: propeller shaft, 27: rear differential, 28a: axle shaft, 28b: rear wheel, 1a, 1b: welded portion, 2: cylinder, 3: body, 3a: friction clutch contact surface, 4: Clutch plate, L: Air gap.

Claims (2)

A magnetic path forming member that is located on one side of the friction clutch and forms a magnetic path that passes through the friction clutch and an armature that is located on the other side of the friction clutch with an electromagnet as a base point. And a cylindrical body made of a non-magnetic material fitted and welded at a radially intermediate portion of the main body , wherein the main body has an annular recess on the friction clutch contact surface. A tip of the tubular body is welded in the recess, and a tip of the tubular body on the friction clutch side with respect to the main body is retracted from the friction clutch contact surface of the main body. A magnetic path forming member for an electromagnetic clutch. In the magnetic path forming member according to claim 1, the magnetic path forming member of the electromagnetic clutch, wherein the friction clutch contact surface is subjected to finishing machining of the body.

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