JP2009243578A - Driving force distribution device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving force distribution device enabling the magnetic permeability of an air gap of an electromagnet to be maintained constant without receiving influence of vibration and the like, enabling great reduction of drag torque, and enabling prevention of variation of clutch transmission torque characteristics. <P>SOLUTION: The driving force distribution device 1 is provided with; a clutch mechanism transmitting torque between a case-shaped input rotary member 20 rotatably supported in a case 2 and an output rotary member 4 relatively rotatably supported in the input rotary member 20; the electromagnet 70 provided at outside of a wall part 23a formed at an input side of the input rotary member 20 and moving toward the clutch mechanism by magnetic attraction force acting against the wall part 23a of the input rotary member 20 by electricity supply; and a spring member 31 put between the case 2 and the electromagnet 70 and energizing the electromagnet 70 toward the wall part 23a of the input rotary member 20. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a driving force distribution device including an electromagnetic friction clutch, and more particularly, to a driving force distribution device that achieves stabilization of a gap of an electromagnet that intermittently operates a clutch mechanism and improves clutch transmission torque characteristics.

  Conventionally, for example, various driving force distribution devices in a four-wheel drive vehicle including an electromagnetic friction clutch have been proposed (see, for example, Patent Document 1). In the conventional driving force distribution device described in Patent Document 1, the fastening of a main clutch that transmits torque between an input rotating member and an output rotating member is adjusted by a pilot clutch that is fastened by energization of an electromagnet. . The pilot clutch is provided in the front housing, and an armature is disposed on one side of the pilot clutch. A rear housing is disposed on the other side of the pilot clutch, and an electromagnet fitted in the yoke is disposed in the rear housing.

  According to this conventional driving force distribution device, a magnetic circuit that circulates between the yoke, the rear housing, the armature, the pilot clutch, the rear housing, and the yoke is formed by energizing the electromagnet. The pilot clutch is fastened by pressing. The cam mechanism that generates a thrust force by the engagement converts the pressing force to the main clutch, and transmits the pressing force to the main clutch, whereby the driving force is transmitted from the input rotating member to the output rotating member.

  The pressing force against the pilot clutch is generated when the magnetic flux excited by the electromagnet coil penetrates the pilot clutch and attracts the armature. For this reason, the pilot clutch requires a configuration that has both the characteristics of being easily magnetized and the friction characteristics of the clutch plate. As a result, the pilot clutch is made of iron, and the sliding surface of the iron clutch plate is subjected to a surface treatment that suppresses wear due to frictional engagement. A nonmagnetic material is embedded in a portion corresponding to the intermediate portion of the pilot clutch of the rear housing constituting a part of the magnetic circuit.

  As a surface treatment of the pilot clutch, a number of fine width grooves or a number of grid-like grooves are formed concentrically on the sliding surface of the clutch plate, and the composition of the sliding surface is nitrided. Alternatively, it is changed by quenching and tempering, or a diamond-like carbon thin film is applied to the sliding surface of the clutch plate. By this surface treatment, the sliding surface of the clutch plate is strengthened to reduce wear.

  Another example of this type of driving force distribution device is a driving force distribution device in which friction clutch paper that functions optimally when lubricated with oil is provided on the sliding surface of the clutch plate of the pilot clutch (for example, patents) Reference 2).

In the conventional driving force distribution device described in Patent Document 2, an electromagnet is fixed in a housing that rotatably supports an input rotation member. The pilot clutch is provided on the inner surface of the input rotation member, and the electromagnet is arranged to face the input rotation member. On the opposite side of the pilot clutch to the input rotation member, an armature (operating plate) connected to the plunger of the electromagnet is arranged oppositely.
JP 2003-28218 A JP 2005-61629 A

  By the way, when lubricated with oil, drag torque is generated by the viscous resistance of the oil interposed between the two surfaces where the clutch plates face each other. One cause of the large drag torque is that the clutch plate sliding surface (friction surface) is wide. That is, the drag torque due to oil viscosity is proportional to the area of the two surfaces where the clutch plates face each other.

  In the conventional driving force distribution device described in Patent Document 1, since the pilot clutch constitutes a part of the magnetic circuit, the cross-sectional area of the magnetic path of the pilot clutch is set to a predetermined size that facilitates magnetism. Must be set. Therefore, in addition to the sliding surface of the clutch plate, a magnetic passage cross section that is not required as the sliding surface of the clutch plate has to be formed, and the pilot clutch has to be formed large. As a result, there is a limit in reducing the drag torque, and there is a problem that it is difficult to reduce the drag torque. In particular, the strength of the differential and drive shaft must be designed on the premise of a large drag torque at low temperatures, and coupled with the increase in the size of the driving force distribution device, the weight of the vehicle body increases and the production cost increases. There was a problem. In addition, since the tight corner braking phenomenon cannot be avoided at low temperatures, there is a problem in that vehicle maneuverability is deteriorated.

  Also, in this conventional driving force distribution device, vibration and noise due to stick-slip are likely to occur because the pilot clutch is friction between irons. As countermeasures, various oil grooves are provided on the sliding surface of the clutch plate, and nitriding treatment or quenching and tempering treatment and diamond-like carbon thin film are applied to provide wear resistance. There was a problem that became high. Even when these treatments are performed, the wear characteristics (μ-V characteristics) of the pilot clutch deteriorate during use due to wear of oil grooves, etc., and there is a problem that vibration and noise of the vehicle occur. . In addition, this conventional driving force distribution device arranges an armature on the front housing side and an electromagnet on the rear housing side with a non-magnetic material embedded in a rear housing constituting a part of the magnetic circuit. There is a problem that the pilot clutch is arranged between the non-magnetic members, and the manufacturing cost of the joint structure with the non-magnetic member is increased.

  On the other hand, in the conventional driving force distribution device described in Patent Document 2, the gap between the electromagnet yoke and the armature (plunger) is maintained through a ball bearing that is largely deformed with respect to an axial load. Has been. Therefore, this conventional driving force distribution device is affected by the positional relationship between the electromagnetic coupling and the housing, the gap between the electromagnet yoke and the armature (plunger) becomes unstable, and the clutch transmission torque characteristics vary from product to product. There was a problem that it occurred.

  Therefore, the present invention has been made to solve the above-described conventional problems, and its specific purpose is to maintain the permeability of the air gap of the electromagnet without being affected by vibration or the like. Furthermore, another object of the present invention is to provide a driving force distribution device that can greatly reduce drag torque and can prevent variations in clutch transmission torque characteristics.

[1] The present invention includes a case having a first internal space, a case-shaped input rotation member rotatably supported in the first internal space of the case and having a second internal space, and the input An output rotating member supported in a relatively rotatable manner in the second internal space of the rotating member; and the second internal space between the input rotating member and the output rotating member, wherein the input rotating member and the output A main clutch that transmits torque between the rotating members, a pilot clutch that adjusts the transmission torque of the main clutch, a cam mechanism that converts the transmission torque of the pilot clutch into a pressing force against the main clutch, and an input rotating member The pilot clutch is provided by a magnetic attraction force provided between the wall portion of the input rotation member by energization and provided outside the wall portion formed on the input side. The driving force distribution device includes: an electromagnet that moves toward the wall; and a spring member that is interposed between the case and the electromagnet and biases the electromagnet toward the wall portion of the input rotation member. .
[2] In the invention described in [1] above, the pilot clutch includes a plurality of clutch plates that are frictionally engaged with each other, and is made of paper on a sliding surface of one of the plurality of clutch plates. It is characterized by the provision of facing.
[3] In the invention described in [1], the input rotating member includes a pressing member that is movably disposed inside the wall portion and presses the pilot clutch, and the pressing member includes the electromagnet The operating force of the pilot clutch is adjusted according to the movement of the pilot clutch.
[4] In the invention described in [3], a thrust needle bearing and a plate member are interposed between the electromagnet and the pressing member.
[5] In the invention described in [1], the electromagnet is supported on an inner peripheral surface of the case.
[6] In the invention described in [1], the electromagnet is supported so as to be relatively rotatable and axially movable with respect to the input rotating member, and is supported so as not to be rotatable with respect to the case. It is characterized by having.

  According to the present invention, it is possible to form a certain gap between the electromagnet and the coupling case without being affected by vibration or the like, and it is possible to prevent deterioration of clutch response. It becomes possible to directly apply a magnetic attractive force acting on the electromagnet to the pilot clutch, and to suppress variations in clutch transmission torque characteristics.

  Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

  The basic configuration of a four-wheel drive vehicle consists of an engine, a transmission, a front differential, a transfer, a pair of left and right front wheel axles, a pair of front wheels, a propeller shaft, a driving force distribution device, a rear differential, a pair of left and right rear wheel axles, and a pair of rear wheels. It is mainly composed. The driving force distribution device and the rear differential are housed and supported in the rear differential case, and are supported by the vehicle body via the rear differential case.

  In the four-wheel drive vehicle configured as described above, the driving force from the engine is transmitted to the front differential via the transmission, and is transmitted to the pair of front wheels via the pair of left and right front wheel axles. On the other hand, the driving force transmitted to the transfer is transmitted to the driving force distribution device via the propeller shaft. When the driving force distribution device is connected so as to be able to transmit torque, the driving force of the engine is transmitted to the rear differential via the drive pinion shaft of the driving force distribution device, and a pair of rear wheels via the left and right rear wheel axles. Is transmitted to.

  FIG. 1 is a cross-sectional view schematically showing an internal structure of a driving force distribution device according to a typical embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part on the front end side of the coupling case. is there.

(Configuration of driving force distribution device)
In FIG. 1, reference numeral 1 schematically shows an overall configuration of a driving force distribution device disposed between a propeller shaft and a rear differential of a four-wheel drive vehicle. The typical driving force transmission device 1 according to the first embodiment includes a coupling case 20 having a rotating shaft portion 21 that is an input rotating member. The coupling case 20 is covered with rear differential cases 2 and 2 which are a combination of a pair of cases extending in the rotation axis direction (vehicle longitudinal direction), and between the inner peripheral surface of the rear differential case 2 and the outer peripheral surface of the coupling case 20. Thus, the required first internal space 3 is formed. Inside the rear differential case 2, a drive pinion shaft 4, which is an output rotating member that rotationally drives the rear differential, is disposed on the same axis as the rotating shaft portion 21 of the coupling case 20.

  As shown in FIG. 1, the rotating shaft portion 21 of the coupling case 20 is fastened and fixed by a nut 6 in the cylindrical portion of the flange 5 on the propeller shaft side to which the driving force from the engine is transmitted. A flange attached integrally with the propeller shaft is connected and fixed to the flange 5.

(Rear differential case configuration)
As shown in FIG. 1, the inner peripheral surface of a cylindrical hub 27 is splined to the front end portion of the drive pinion shaft 4, and is supported by the coupling case 20 via a bearing 15 so as to be relatively rotatable. Yes. The rear end portion of the drive pinion shaft 4 is rotatably supported on the inner peripheral surface of the rear differential case 2 via a pair of tapered roller bearings 7 and 7 and is integrated by a spacer and a nut. A gear 8 that meshes with a rear differential gear mechanism is integrally formed at the front end of the rear end of the drive pinion shaft 4.

  As shown in FIG. 1, a cylindrical wall portion 9 serving as a bearing portion of the coupling case 20 extends toward the coupling side at the rear end portion of the rear differential case 2. An oil seal 10 is disposed between an opening formed at the front end portion of the rear differential case 2 and the outer peripheral surface of the flange 5 on the propeller shaft side. An oil seal 11 is disposed between the inner peripheral surface of the cylindrical wall portion 9 of the rear differential case 2 and the drive pinion shaft 4. The oil seals 10 and 11 partition the first internal space 3 of the rear differential case 2 and the third internal space 18 on the rear differential side, and the internal space 3 is sealed. A dust cover 12 is fixed to the flange 5 on the propeller shaft side to prevent dust and the like from entering the internal space 3 of the rear differential case 2.

(Composition of coupling case)
As shown in FIG. 1, the coupling case 20 includes a cylindrical portion 22 having a larger diameter than the rotating shaft portion 21, a first housing 23 having a larger diameter than the cylindrical portion 22, and the rear of the first housing 23. It has a multi-stage shape including an annular second housing 24 in which the end opening is fixed in a liquid-tight manner. A cylindrical opening tube portion 25 is formed on the rear end surface of the second housing 24. The rotating shaft portion 21 is rotatably supported in the rear differential case 2 via a bearing 13, and the opening cylindrical portion 25 of the second housing 24 is connected to the cylindrical wall portion 9 of the rear differential case 2 via a bearing 14 with a seal. It is rotatably supported on the inner peripheral surface.

  According to the illustrated example, in the driving force distribution device 1, the second inner portion of the coupling case 20 is formed by the oil seal 11 interposed between the inner peripheral surface of the cylindrical wall portion 9 of the rear differential case 2 and the drive pinion shaft 4. A space 26 and a third inner space 18 on the rear differential side are partitioned. By forming the annular installation space by the oil seal 11 and the bearing 14 with the seal, an oil reservoir 80 for storing the lubricating oil repelled from the inner space 3 of the rear differential case 2 by the rotation of the driving force distribution device 1 is provided. It is configured.

  Between the outer peripheral surface of the cylindrical portion 22 of the coupling case 20 and the inner peripheral surface of the rear differential case 2, an annular arrangement space 28 in which the electromagnet 70 is arranged is formed. On the input side of the first housing 23, an annular step wall 23 a that forms a step surface facing the electromagnet 70 is provided. An annular recess 23b is formed in the step wall portion 23a. A plurality of through holes 23c,..., 23c are formed in the bottom surface of the annular recess 23b in the axial direction with a predetermined phase difference on the same circumference around the rotation axis of the coupling case 20. . A pressing member 53 for adjusting the pressing force of the pilot clutch 50 is accommodated in each of the through holes 23c so as to be movable in the axial direction.

(Configuration of clutch mechanism)
As shown in FIG. 1, the driving force distribution device 1 has a clutch mechanism that controls torque transmission between the coupling case 20 and the drive pinion shaft 4 arranged in the coupling case 20 on the same axis as the rotary shaft portion 21. is doing. In this clutch mechanism, by applying current to the electromagnet 70, the magnetic attractive force acting on the electromagnet 70 between the stepping wall portion 23 a of the coupling case 20 and the operating force that moves the electromagnet 70 toward the pilot clutch 50 It has the feature. The basic structure of this clutch mechanism includes a main clutch 40, an electromagnetic pilot clutch 50 that adjusts the transmission torque of the main clutch 40, and a cam mechanism 60 that converts the transmission torque of the pilot clutch 50 into a pressing force against the main clutch 40. It is mainly configured by. The driving force distribution device 1 further includes an electromagnet 70 that intermittently operates the clutch mechanism, and a pressing member 53 that presses the pilot clutch 50 with a magnetic attractive force acting on the electromagnet 70.

(Configuration of main clutch)
As shown in FIG. 1, the main clutch 40 is splined to a plurality of annular outer clutch plates 41 splined to the inner circumferential surface of the first housing 23 of the coupling case 20 and the outer circumferential surface of the hub 27. And a plurality of annular inner clutch plates 42. Between the main clutch 40 and the second housing 24, an annular spacer 43 that regulates the clearance of the clutch is disposed. A plurality of circular oil holes 44,..., 44 having a predetermined phase difference are formed on the same circumference around the rotation axis of the coupling case 20 at portions other than the friction engagement surface of the inner clutch plate 42. Has been. The main clutch 40 is fastened via a pressure ring 61 of a cam mechanism 60 that moves to the main clutch 40 side when the pilot clutch 50 is fastened. When the main clutch 40 is engaged, the first housing 23 and the hub 27 are connected, so that driving force is transmitted from the coupling case 20 to the drive pinion shaft 4.

(Configuration of pilot clutch)
As shown in FIG. 1, the pilot clutch 50 includes two annular outer clutch plates 51, 51 and one annular inner clutch plate 52. The outer clutch plate 51 is splined to the inner peripheral surface of the first housing 23. One inner clutch plate 52 is splined to a cam ring 62 of the cam mechanism 60. A plurality of circular oil holes 54,..., 54 are formed on the same circumference around the rotation axis of the coupling case 20 at a portion other than the friction engagement surface of the inner clutch plate 52 with a predetermined phase difference. Has been. It is preferable to use paper facing on one clutch plate sliding surface of the clutch plates 51 and 52 of the pilot clutch 50. The drag torque of the pilot clutch 50 is greatly reduced, and stable and good friction characteristics and durability are maintained over a long period of time without expensive oil groove processing or surface treatment. Note that a paper facing may be attached to one of the sliding surfaces of the outer clutch plate 41 and the inner clutch plate 42 of the main clutch 40.

  When the electromagnet 70 is energized, the electromagnet 70 is attracted and moved to the pilot clutch 50 side. The pressing member 53 is moved to the pilot clutch 50 side by the pressing force, and the pilot clutch 50 is fastened by the pressing force. At this time, a rotational torque is generated between the cam ring 62 and the pressure ring 61, so that a thrust force is generated in the cam mechanism 60. In the illustrated example, the number of inner clutch plates 52 of the pilot clutch 50 is set to one, but is not limited to this. In the first embodiment, for example, the number of inner clutch plates 52 may be set to two or three or more.

(Composition of cam mechanism)
As shown in FIG. 1, the cam mechanism 60 includes a pressure ring 61, a cam ring 62, and a cam ball 63 disposed between the pressure ring 61 and the cam ring 62. The cam mechanism 60 is received on the inner peripheral surface of the step wall portion 23 a of the first housing 23 of the coupling case 20 by a thrust bearing 64 and is disposed on the outer peripheral surface of the hub 27. A circular oil passage 65 is formed through the pressure ring 61 so as to correspond to the oil hole 44 of the outer clutch plate 41 of the main clutch 40. The oil passage 65 is disposed at a position facing the oil hole 44 of the inner clutch plate 42 of the main clutch 40.

  As shown in FIG. 1, the cam mechanism 60 controls the fastening force of the main clutch 40 steplessly. When the pilot clutch 50 is engaged by energization of the electromagnet 70, rotational torque is generated between the cam ring 62 and the pressure ring 61 connected to the pilot clutch 50. Due to the thrust force that the cam ball 63 presses the cam ring 62 and the pressure ring 61 away from each other, the pressure ring 61 moves toward the main clutch 40 and the main clutch 40 is fastened.

(Configuration of electromagnet)
As shown in FIG. 1, the electromagnet 70 is formed in an annular shape by a yoke 71 and a coil 72. The yoke 71 has an annular recess 73 having a U-shaped cross section that is open to the main clutch 40 side. In the recess 73, an annular coil 72 held concentrically is sealed in a liquid-tight manner. An annular nonmagnetic member 74 made of stainless steel or the like is embedded in a portion facing the coil 72. The nonmagnetic member 74 prevents a short circuit of the magnetic flux of the electromagnet 70. The electromagnet 70 has a predetermined space between the stepped wall portion 23 a of the coupling case 20 in an annular arrangement space 28 formed between the outer peripheral surface of the cylindrical portion 22 of the coupling case 20 and the inner peripheral surface of the rear differential case 2. A gap G is supported on the inner peripheral surface of the rear differential case 2 so that it cannot rotate but can move in the axial direction.

  The electromagnet 70 is connected to the rear differential case 2 via a grommet 75 and lead wires 76 drawn to the outside. When the electromagnet 70 is energized via the lead wire 76, a magnetic path L that circulates between the yoke 71 and the step wall portion 23a of the coupling case 20 without passing magnetism through the pilot clutch 50 is formed. A load attracted to the stepped wall portion 23 a of the coupling case 20 (magnetic attraction acting on the electromagnet 70) is directly applied to the pilot clutch 50. The pressing force to the pilot clutch 50 can be adjusted by adjusting the energization power to the electromagnet 70. The electromagnet 70 and the stepped wall portion 23a of the coupling case 20 are arranged close to each other, so that magnetic flux leakage can be reduced and magnetic force can be used efficiently.

  In this embodiment, the configuration in which the electromagnet 70 is supported on the inner peripheral surface of the rear differential case 2 is exemplified, but the present invention is not limited to this. Instead of this configuration, for example, the electromagnet 70 can be supported on the cylindrical portion 22 of the coupling case 20. The electromagnet 70 is supported on the outer peripheral surface of the cylindrical portion 22 of the coupling case 20 so as to be relatively rotatable via a bearing, and is supported so as to be movable in the axial direction, thereby rotating relative to the inner peripheral surface of the rear differential case 2. It can be set as the structure which cannot be supported.

(Configuration of pressing member)
In the through hole 23c of the annular recess 23b formed in the step wall portion 23a of the coupling case 20, as shown in FIG. The pressing member 53 is constituted by a circular block body having a circular flange at one end. A thrust needle bearing 55 facing the nonmagnetic member 74 of the electromagnet 70 and a ring plate 56 facing the pressing member 53 are juxtaposed in the annular recess 23b of the step wall 23a. The magnetic attractive force acting on the electromagnet 70 is transmitted to the nonmagnetic member 74, the thrust needle bearing 55, the ring plate 56, and the pressing member 53, and becomes a pressing force to the pilot clutch 50.

  In the clutch mechanism configured as described above, the magnetic attraction force acting on the electromagnet 70 with the coupling case 20 is used as the operating force for the pilot clutch 50, so the pilot clutch 50 is configured as a part of the magnetic path L. There is no need to do. In addition to the clutch plate sliding surface of the pilot clutch 50, the magnetic path cross section that is not required as the clutch plate sliding surface is not formed, so that the pilot clutch 50 can be configured compactly with a small current. A large torque can be controlled.

(Electromagnet position restriction means)
FIG. 2 is an enlarged cross-sectional view of a main part on the front end side of the coupling case. In the figure, an electromagnet 70 is supported between the outer ring end surface 13 a of the coupling case supporting bearing 13 and the stepped wall portion 23 a of the coupling case 20. The yoke 71 of the electromagnet 70 has a contact portion when it contacts the outer ring end surface 13 a of the bearing 13. An annular convex portion 71b that is narrower than the width of the outer ring end surface 13a of the bearing 13 is formed on the contact portion over the entire circumference of the outer ring end surface 13a of the bearing 13 via the annular concave portion 71a. By bringing the yoke 71 into contact with the outer ring end surface 13a of the bearing 13, the retracted position of the electromagnet 70 can be regulated and the permeability of the gap G can be kept constant.

  When the coil 72 of the electromagnet 70 is energized, a magnetic path L that circulates between the yoke 71 of the electromagnet 70 and the step wall portion 23a of the coupling case 20 is formed. However, since the yoke 71 and the bearing 13 are made of a magnetic material, Magnetic flux leaks from the path L through the yoke 71 and the bearing 13. In this embodiment, leakage of magnetic flux is prevented by reducing the contact surfaces of the yoke 71 and the bearing 13. Since the magnetic attractive force acting on the electromagnet 70 is stabilized, the control of the engagement / disengagement of the pilot clutch 50 is facilitated, and the driving force transmission function of the driving force distribution device 1 can be improved. An annular concavo-convex portion that is narrower than the width of the outer ring end surface 13 a of the bearing 13 may be formed in the contact portion that contacts the outer ring end surface 13 a of the bearing 13 of the yoke 71 of the electromagnet 70.

  Between the electromagnet 70 and the rear differential case 2, a breather chamber 30 is provided in the rear differential case 2 to release the increased internal pressure to the atmosphere. The electromagnet 70 forms a partition wall that covers the breather chamber 30, and partitions the breather chamber 30 and the internal space 3 of the rear differential case 2. Between the yoke 71 of the electromagnet 70 and the end surface of the rear differential case 2 that forms the peripheral surface of the breather chamber 30, an annular disc spring 31 that is a spring member is interposed via an outer ring of the bearing 13. The electromagnet 70 is biased toward the step wall portion 23 a of the coupling case 20 by the elastic force of the disc spring 31. The breather chamber 30 is liquid-tightly sealed by the disc spring 31.

  Since the disc spring 31 is urged toward the electromagnet 70, a constant gap G can be formed between the electromagnet 70 and the coupling case 20 even when vibration is applied to the electromagnet 70, and the clutch response. Can be prevented. Even when the current applied to the electromagnet 70 is a low current, it becomes possible to prevent the coupling case 20 from rattling in the direction of the rotation axis, thereby preventing poor suction to the coupling case 20 due to variations in the gap G. can do. In the illustrated example, the yoke 71 of the electromagnet 70 is in contact with the outer ring end surface 13a of the bearing 13 via the disc spring 31. However, the present invention is not limited to the illustrated example, and for example, via a coil spring. The yoke 71 of the electromagnet 70 may be in contact with the outer ring end surface 13a of the bearing 13.

(Configuration of oil circulation path)
The driving force distribution device 1 provided with this clutch mechanism is used in a state accompanied by slipping of a plurality of clutch plates that are frictionally engaged or separated from each other. For this reason, overheating due to frictional heat between the clutch plates, wear of the clutch plates, running out of oil, and the like occur, so that lubricating oil for lubricating and cooling the clutch plates is supplied into the coupling case 20.

  According to the illustrated example, the oil seal 11 interposed between the inner peripheral surface of the cylindrical wall portion 9 of the rear differential case 2 and the drive pinion shaft 4 causes the second inner space 26 of the coupling case 20 and the rear differential-side 3 internal spaces 18 are partitioned. By forming an annular installation space on the main clutch fastening side of the coupling case 20 by the oil seal 11 and the bearing 14 with the seal, the drive force distribution device 1 is repelled from the internal space 3 of the rear differential case 2 by rotation. An oil reservoir 80 is provided for storing lubricating oil. The splashed lubricating oil is collected in an oil garter (not shown). The collected lubricating oil flows toward the downstream side of the oil garter and is temporarily stored in the oil reservoir 80.

  The lubricating oil stored in the oil reservoir 80 agitates the internal space 26 of the coupling case 20 by centrifugal force generated by the rotation of the coupling case 20. The stirred lubricating oil receives a centrifugal force due to the rotation of the coupling case 20, is captured in the discharge hole 29 of the coupling case 20, and is discharged into the inner space 3 of the rear differential case 2. The lubricating oil is used again for lubricating and cooling the clutch mechanism. This makes it possible to effectively lubricate and cool the clutch mechanism with a small flow rate of lubricating oil.

(Effect of embodiment)
According to the driving force distribution device 1 according to the embodiment, the following various effects can be obtained.
(1) Since the disc spring 31 is urged to the electromagnet 70, a constant gap G can be formed between the electromagnet 70 and the coupling case 20 even when vibration is applied to the electromagnet 70. It is possible to obtain the improved clutch response.
(2) Even when the applied current to the electromagnet 70 is a low current, it is possible to prevent the generation of abnormal noise due to rattling or vibration in the rotational axis direction of the coupling case 20, and the gap G varies. It is possible to prevent a suction failure with respect to the coupling case 20 due to the above.
(3) Since the oil pilot machining is not required for the iron pilot clutch 50 and an expensive surface treatment is not required, the machining cost can be reduced, and good friction characteristics and durability stable over a long period of time can be achieved. Can be maintained.
(4) The drag torque at low temperatures due to the viscosity of the oil can be greatly reduced, and it is possible to achieve a reduction in size and weight by avoiding an increase in the strength of the differential and the drive shaft, and manufacturing at low cost. be able to.
(5) Since the electromagnet 70 is brought into contact with the outer ring end surface 13a of the bearing 13 for supporting the coupling case, the retracted position of the electromagnet 70 can be restricted, and the electromagnet 70 and the coupling case 20 can be regulated. The gap G is stabilized, and variations in clutch transmission torque characteristics can be reduced.
(6) Since the leakage of magnetic flux from the magnetic path L can be greatly reduced by reducing the contact surfaces of the electromagnet 70 and the bearing 13, a large torque can be generated with a small current.
(7) Since a large torque can be controlled with a small current, the cost of the controller is also low.
(8) It is not necessary to provide the coupling case 20 with a non-magnetic bonding structure for blocking magnetism, and the manufacturing cost can be reduced.
(9) Since the load attracted to the coupling case 20 of the electromagnet 70 is directly applied to the pilot clutch 50, a paper facing can be used for the pilot clutch 50, and the clutch plate 51 can be used. , 52 can reduce the area of the sliding surface. As a result, the drag torque due to the viscosity of the oil can be greatly reduced, and the fuel consumption can be improved.
(10) The armature disposed in the coupling case 20 is eliminated, and the magnetic attractive force acting on the electromagnet 70 between the coupling case 20 and the electromagnet 70 moves toward the pilot clutch 50. Therefore, the installation structure of the pilot clutch mechanism can be simplified and the installation space in the coupling case 20 can be used effectively.
(11) Since the pilot clutch mechanism can be configured in a compact manner, it is possible to reduce the weight and size of the entire device and improve the on-vehicle performance.

  As is clear from the above description, the driving force distribution device according to the present invention is applied to the driving force distribution between the front and rear wheels, so that only the front wheels or only the rear wheels are driven in the 2WD mode, depending on the vehicle state. An auto mode that automatically controls the driving force between the front and rear wheels and a lock mode that maintains the maximum driving force can be provided. The present invention is not limited to the above-described embodiments and modifications, and various design changes can be made within the scope described in each claim.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used for a driving force distribution device in various vehicles such as work vehicles such as agricultural machines, construction engineering machines, and transport machines, buggy cars, and automobiles.

It is sectional drawing which shows roughly the internal structure of the driving force distribution apparatus which is typical embodiment of this invention. It is a principal part cross-sectional enlarged view of the front-end part side of a coupling case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drive force distribution apparatus 2 Rear differential case 3 1st interior space 4 Drive pinion shaft 5 Flange 6 Nut 7 Tapered roller bearing 8 Gear 9 Cylindrical wall part 10, 11 Oil seal 12 Dust cover 13, 15 Bearing 13a Outer ring end surface 14 With a seal Bearing 18 Third inner space 20 Coupling case 21 Rotating shaft portion 22 Cylindrical portion 23 First housing 23a Stepped wall portion 23b Annular recess 23c Through hole 24 Second housing 25 Open cylindrical portion 26 Second inner space 27 Hub 28 Arrangement space 29 Discharge hole 30 Breather chamber 31 Belleville spring 40 Main clutch 41 Outer clutch plate 42 Inner clutch plate 43 Spacer 44, 54 Oil hole 50 Pilot clutch 51 Outer clutch plate 52 Inner clutch plate 53 Pressing member 55 Thrust needle bearing 56 Ring plate 60 Cam mechanism 61 Pressure ring 62 Cam ring 63 Cam ball 64 Thrust bearing 65 Oil path 70 Electromagnet 71 Yoke 71a, 73 Recess 71b Protrusion 72 Coil 74 Nonmagnetic member 75 Grommet 76 Lead wire 80 Oil reservoir G Gap L Magnetic path

Claims (6)

A case having a first internal space;
A case-shaped input rotation member rotatably supported in the first internal space of the case and having a second internal space;
An output rotating member supported in a relatively rotatable manner in the second internal space of the input rotating member;
A main clutch that is in the second internal space between the input rotating member and the output rotating member and transmits torque between the input rotating member and the output rotating member;
A pilot clutch for adjusting the transmission torque of the main clutch;
A cam mechanism for converting the transmission torque of the pilot clutch into a pressing force against the main clutch;
An electromagnet which is provided outside the wall portion formed on the input side of the input rotation member and moves toward the pilot clutch by a magnetic attractive force acting between the wall portion of the input rotation member by energization;
A driving force distribution device comprising: a spring member interposed between the case and the electromagnet and biasing the electromagnet toward the wall of the input rotation member. The pilot clutch has a plurality of clutch plates frictionally engaged with each other,
2. The driving force distribution device according to claim 1, wherein a paper facing is provided on a sliding surface of one of the plurality of clutch plates. It is arranged to be movable inside the wall portion of the input rotation member, and has a pressing member that presses the pilot clutch,
The driving force distribution device according to claim 1, wherein the pressing member adjusts the operating force of the pilot clutch according to the movement of the electromagnet.   4. A driving force distribution device according to claim 3, wherein a thrust needle bearing and a plate member are interposed between the electromagnet and the pressing member.   The driving force distribution device according to claim 1, wherein the electromagnet is supported on an inner peripheral surface of the case.   2. The driving force according to claim 1, wherein the electromagnet is supported so as to be relatively rotatable and axially movable with respect to the input rotating member, and is supported so as not to rotate with respect to the case. Distribution device.

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