JP2009236176A - Drive force transmitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive force transmitting device capable of enhancing traction performance in an initial period of a wheel speed difference generation and capable of enhancing traveling stability of a vehicle. <P>SOLUTION: The drive force transmitting device 6 is provided with a piston 62 for axially pressing a main clutch 34 from an opposite side in an axial direction of a main cam 39 and an interlocking member 64 for reducing a pressing force which the piston 62 applies to the main clutch 34 based on increase of a pressing force generated by a cam mechanism 36. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a driving force transmission device.

  2. Description of the Related Art Conventionally, a cylindrical first rotating member and a shaft-shaped second rotating member that is coaxially arranged rotatably in the first rotating member are provided, and between the first rotating member and the second rotating member. There is a driving force transmission device in which a first rotating member and a second rotating member can be connected so as to transmit torque by a clutch mechanism provided. Such a driving force transmission device is provided in the middle of a drive transmission system in a four-wheel drive vehicle, and has a driving force distribution characteristic between main driving wheels (mainly front wheels) and auxiliary driving wheels (mainly rear wheels). It is supposed to change.

For example, Patent Document 1 discloses a pilot clutch that is juxtaposed in the axial direction of a clutch mechanism (main clutch), and a cam mechanism that is provided between the main clutch and the pilot clutch and presses the main clutch in the axial direction by the operation of the pilot clutch. A driving force transmission device having a pressing force generating means constituted by the following is disclosed. The cam mechanism includes a first cam member and a second cam member that can rotate relative to each other on the same rotation shaft, and a cam follower that is sandwiched between cam grooves formed on the respective opposing surfaces. The cam mechanism causes the cam follower to cam as a result of the first cam member and the second cam member rotating relative to each other by torque based on the rotational difference between the first rotating member and the second rotating member transmitted via the pilot clutch. The groove is rolled so that the first cam member and the second cam member are separated and the first cam member presses the main clutch.
JP 2002-61677 A

  By the way, in Patent Document 1, the clutch mechanism is frictionally engaged unless a relative rotation occurs between the first rotating member and the second rotating member, that is, if there is no wheel speed difference between the front wheel and the rear wheel. Torque is not transmitted. For this reason, for example, when a slip occurs at the start of the vehicle, there is a possibility that sufficient torque is not distributed to the auxiliary drive wheels at the initial stage of the difference in wheel speed, resulting in a large slip and a decrease in traction performance. . Such a problem is not limited to the case where the main clutch is pressed by the cam mechanism, but the clutch mechanism is pressed by the axial pressing force generated based on the rotation difference between the first rotating member and the second rotating member. The same occurs in the driving force transmission device having the configuration.

  Therefore, even when the axial pressing force generated based on the rotation difference between the first rotating member and the second rotating member does not act, the clutch mechanism is pressed, that is, the pre-torque is applied to the clutch mechanism, thereby assisting driving. It is conceivable to constantly transmit torque to the wheels to improve the traction performance in the initial stage of occurrence of a wheel speed difference such as when starting. However, when torque is always transmitted to the auxiliary drive wheels, for example, when the turning radius of the vehicle is small, the so-called tight corner braking phenomenon in which the difference in rotation between the front and rear wheels cannot be absorbed and the front and rear wheels are braked. There is a possibility that the running stability of the vehicle may be reduced.

  The present invention has been made to solve the above-described problems, and its object is to improve the traction performance at the initial stage of occurrence of the wheel speed difference and the driving force capable of improving the running stability of the vehicle. It is to provide a transmission device.

  In order to achieve the above object, the invention according to claim 1 includes a cylindrical first rotating member, a shaft-shaped second rotating member that is coaxially disposed in the first rotating member, and the first rotating member. A clutch mechanism in which an outer clutch plate that rotates integrally with one rotating member and an inner clutch plate that rotates integrally with the second rotating member are alternately arranged; a pressing force generating means for generating an axial pressing force; and the pressing force A first pressing member that moves in the axial direction according to the pressing force generated by the generating means and presses the clutch mechanism, and changes a torque transmission capacity between the first rotating member and the second rotating member. In the driving force transmission device configured to be possible, a second pressing member that presses the clutch mechanism in the axial direction from an axially opposite side of the first pressing member, and a pressing force generated by the pressing force generating means Increase Said second pressing member is summarized in that with a reduction means for reducing the pressing force applied to the clutch mechanism based on.

  According to the above configuration, even when the pressing force generating means is not in operation, the clutch mechanism is frictionally engaged by being pressed by the second pressing member, so that a predetermined torque can be transmitted to the auxiliary driving wheel. For example, even when slip occurs at the start of the vehicle, a predetermined torque is distributed to the auxiliary drive wheels even in the early stage of occurrence of the wheel speed difference to prevent the slip from increasing and improve the traction performance. Can do. Further, the reducing means reduces the frictional engagement force of the clutch mechanism by reducing the pressing force applied to the clutch mechanism by the second pressing member based on the increase of the pressing force generated by the pressing force generating means, For example, when the turning radius of the vehicle is small, the occurrence of a tight corner braking phenomenon can be prevented, and the running stability of the vehicle can be improved.

  According to a second aspect of the present invention, in the driving force transmission device according to the first aspect, the inner clutch plate penetrates into an inner peripheral side of a sliding portion that slides with the outer clutch plate in the inner clutch plate. A hole is formed, and the reducing means is inserted into the through hole, and the first pressing member and the second pressing member are moved in the axial direction of either the first pressing member or the second pressing member. The gist of the invention is that it is an interlocking member that interlocks and moves either one of the pressing members. According to the above configuration, since the first pressing member and the second pressing member move in conjunction with each other by the interlocking member, the first pressing member moves in the axial direction toward the clutch mechanism, whereby the second pressing member. The pressing force applied to the clutch mechanism can be reduced. Further, since the interlocking member is inserted into the through hole formed in the inner clutch plate, the apparatus can be prevented from being enlarged.

  According to a third aspect of the present invention, in the driving force transmission device according to the first or second aspect, the first rotating member is formed in a bottomed cylindrical shape, and an outer peripheral edge of the bottom portion of the first rotating member is An abutting portion with which the clutch mechanism pressed against the first pressing member abuts is formed extending in the axial direction, and the second pressing member is disposed on an inner peripheral side of the abutting portion, The gist is that the clutch mechanism is biased by an elastic member provided between the two pressing members and the bottom. According to the said structure, since the 2nd press member is arrange | positioned in the inner peripheral side of the contact part which the clutch mechanism pressed by the 1st press member contact | abuts, the enlargement of an apparatus can be prevented. Moreover, since the 2nd press member is pressed by the elastic member provided between the bottom parts, it can press a 2nd press member by simple structure.

  According to a fourth aspect of the present invention, there is provided the driving force transmission device according to the third aspect, wherein the first pressing member and the clutch mechanism are not in contact with each other when the pressing force generating means is inactive. A gap is formed between the contact portion and the clutch mechanism, a second gap that is equal to or smaller than the first gap is formed, and between the second pressing member and the bottom portion, A third gap that is equal to or greater than the first gap is formed, and the elastic member is configured to be elastically deformable beyond the first gap. According to the above configuration, the axial movement of the first pressing member causes the second pressing member to move to the opposite side in the axial direction of the clutch mechanism beyond the second gap, that is, the second pressing member becomes the clutch mechanism. Since the applied pressing force can be reduced to 0, the tight corner braking phenomenon can be reliably prevented.

  The gist of a fifth aspect of the present invention is the driving force transmission device according to any one of the second to fourth aspects, wherein the interlocking member is made of a rigid body. According to the above configuration, since the interlocking member is made of a rigid body, the first pressing member and the second pressing member are not deformed even when pressed by the first pressing member or the second pressing member, and the first pressing member and the second pressing member are in the axial direction. Move in the axial direction without changing the relative distance. Therefore, it is possible to efficiently reduce the pressing force applied by the second pressing member to the clutch mechanism in accordance with the axial movement of the first pressing member. Accordingly, in order to reduce the pressing force applied to the clutch mechanism by the second pressing member, for example, compared with the case where the interlocking member is made of an elastic material, the distance that the first pressing member moves in the axial direction is shortened. Therefore, it is possible to prevent an increase in the size of the apparatus in the axial direction.

  ADVANTAGE OF THE INVENTION According to this invention, the driving force transmission device which can aim at the improvement of the traction performance in the generation | occurrence | production initial stage of a wheel speed difference and can improve the driving | running | working stability of a vehicle can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the vehicle 1 is a four-wheel drive vehicle based on a front-wheel drive vehicle, and an engine 2 is mounted on the front portion (left side in FIG. 1) of the vehicle 1 and assembled to the engine 2. A pair of front axles 4 are connected to the transaxle 3. A propeller shaft 5 is connected to the transaxle 3 together with the front axles 4, and the propeller shaft 5 can be connected to a pinion shaft (drive pinion shaft) 7 via a driving force transmission device 6. ing. The pinion shaft 7 is connected to a pair of rear axles 9 via a rear differential gear 8. Accordingly, the torque of the engine 2 is transmitted from the transaxle 3 to the front wheel 10f through the front axle 4, and from the transaxle 3, the propeller shaft 5, the driving force transmission device 6, the pinion shaft 7, the rear differential gear 8, and the various It is transmitted to the rear wheel 10r via the rear axle 9. In addition, the ECU 11 is connected to the driving force transmission device 6. The ECU 11 supplies a driving current to the driving force transmission device 6 in accordance with the running state of the vehicle, and controls the operation of the driving force transmission device 6 through this current supply, whereby a torque capacity that can be transmitted to the rear wheel 10r, that is, a torque. The transmission capacity is controlled. The driving force transmission device 6 is housed in the differential carrier 12 together with the rear differential gear 8.

  As shown in FIG. 2, the driving force transmission device 6 includes a bottomed cylindrical front housing 22 rotatably accommodated in a coupling case 21 of a differential carrier 12, and is rotatable within the cylinder of the front housing 22. And an axial inner shaft 23 arranged coaxially therewith.

  The front housing 22 as a first rotating member is rotatably supported by a ball bearing 25 with its bottom 24 (left side in the figure) exposed to the outside of the coupling case 21 and its open end 26. A ring-shaped rear housing 27 is fitted into the housing. The inner shaft 23 as the second rotating member is rotatably supported by a needle bearing 28 provided on the inner periphery of the rear housing 27 and a ball bearing 29 provided in a cylinder of the front housing 22. The cylinder of the front housing 22 is fitted by a fitting portion between the front housing 22 and the rear housing 27 and seal members 30 and 31 provided between the inner periphery of the rear housing 27 and the outer periphery of the inner shaft 23. Sealed and lubricating oil is contained in the cylinder.

  The bottom portion 24 of the front housing 22 is connected to a flange portion (not shown) provided on the propeller shaft 5 by a bolt 32. Thereby, the front housing 22 rotates by the input of the torque which the engine 2 which is a drive source generate | occur | produces. Further, a connecting portion (spline fitting portion) 33 with the pinion shaft 7 is formed on the inner periphery of the shaft end (right side in the figure) of the inner shaft 23 supported by the needle bearing 28. . Therefore, when the driving force transmission device 6 is mounted on the vehicle 1, the front housing 22 is connected to the front wheel 10f side which is the main driving wheel, and the inner shaft 23 is connected to the rear wheel 10r side which is the auxiliary driving wheel. It is like that.

  A main clutch 34 is provided in the cylinder of the front housing 22 so that the front housing 22 and the inner shaft 23 can be connected to transmit torque, and a pilot clutch 35 is provided on the axial rear housing 27 side of the main clutch 34. Are juxtaposed. A cam mechanism 36 is provided between the main clutch 34 and the pilot clutch 35.

  The main clutch 34 as a clutch mechanism employs a multi-plate friction clutch in which a plurality of outer clutch plates 37 and inner clutch plates 38 provided so as to be movable in the axial direction are alternately arranged. Specifically, each outer clutch plate 37 is spline-fitted to the inner periphery of the front housing 22, and each inner clutch plate 38 is spline-fitted to the outer periphery of the inner shaft 23 to be movable in the axial direction. And it is provided so as to be able to rotate integrally with the corresponding front housing 22 or inner shaft 23. In the main clutch 34, the outer clutch plate 37 and the inner clutch plate 38 are pressed in the axial direction and frictionally engaged with each other, thereby connecting the front housing 22 and the inner shaft 23 so as to transmit torque. Yes. The transmission torque between the front housing 22 and the inner shaft 23 changes according to the frictional engagement force between the outer clutch plates 37 and the inner clutch plates 38, that is, the axial pressing force. In the present embodiment, the main clutch 34 is configured by disposing outer clutch plates 37 on both ends in the axial direction.

  The cam mechanism 36 is rotatably supported by the inner shaft 23 and the main cam 39 provided so as to be integrally rotatable with the inner shaft 23 by being spline fitted to the outer periphery of the inner shaft 23 and to be movable in the axial direction. A pilot cam 40 and a cam follower 41 interposed between the pilot cam 40 and the main cam 39 are provided. Both the main cam 39 and the pilot cam 40 as the first pressing member are formed in an annular shape. The main cam 39 is disposed on the main clutch 34 side, and the pilot cam 40 is disposed on the rear housing 27 side. The main cam 39 is spline-fitted to the pilot clutch 35 side of the spline groove of the inner shaft 23. Further, the pilot cam 40 is in contact with a needle bearing 42 provided between the pilot cam 40 and the rear cam 27, and is supported so as to be relatively rotatable with a predetermined distance from the rear housing 27.

  A plurality of cam grooves 43 and 44 (see FIG. 3) inclined with respect to the circumferential direction are formed on the opposing surfaces of the main cam 39 and the pilot cam 40 so as to oppose each other, and the cam follower 41 opposes each other. It is sandwiched between the main cam 39 and the pilot cam 40 in a state of being arranged in each cam groove 43, 44. The cam grooves 43 and 44 are formed in a U-shaped cross section, and are formed so that the depth becomes shallower from the center in the circumferential direction toward both ends in the circumferential direction. In the cam mechanism 36, when the main cam 39 and the pilot cam 40 rotate relative to each other, the cam follower 41 rolls in the cam grooves 43 and 44 so that the main cam 39 and the pilot cam 40 are separated, that is, the main cam 39 is the main cam 39. It moves in the axial direction toward the clutch 34.

  In the present embodiment, a step portion 39a is formed on the radially outer side of the surface of the main cam 39 facing the main clutch 34, and is thinner than the radially inner side. A thrust bearing 45 is provided at the stepped portion 39 a, and the main cam 39 presses the outer clutch plate 37 through the thrust bearing 45. Thus, the main cam 39 presses the outer clutch plate 37 while allowing relative rotation between the main cam 39 and the outer clutch plate 37. When the main clutch 34 is pressed by the main cam 39, the outer clutch plate 37 disposed on the bottom 24 side comes into contact with a contact portion 46 formed to extend from the outer peripheral edge of the bottom 24 in the axial direction, It is sandwiched between the main cam 39 and the contact portion 46 so as to be frictionally engaged.

  Like the main clutch 34, the pilot clutch 35 employs a multi-plate friction clutch in which a plurality of outer clutch plates 48 and inner clutch plates 49 that are provided so as to be movable in the axial direction are alternately arranged. Yes. Specifically, each outer clutch plate 48 is spline-fitted to the inner periphery of the front housing 22, and the inner clutch plate 49 is spline-fitted to the outer periphery of the pilot cam 40, thereby moving in the axial direction. And it is provided so as to be able to rotate integrally with the corresponding front housing 22 or pilot cam 40. The pilot clutch 35 is configured such that the outer clutch plate 48 and the inner clutch plate 49 are pressed in the axial direction and frictionally engaged with each other, thereby connecting the front housing 22 and the pilot cam 40 so as to transmit torque. It has become.

  That is, the pilot cam 40 with the cam follower 41 sandwiched between the main cam 39 rotates together with the main cam 39, that is, the inner shaft 23, when the pilot clutch 35 is not in operation, and between the front housing 22 and the pilot cam 40. A rotation difference corresponding to the rotation difference between the front housing 22 and the inner shaft 23 is generated. The pilot clutch 35 is operated to connect the front housing 22 and the pilot cam 40 so as to be able to transmit torque, thereby camming torque based on the rotational difference between the front housing 22 and the inner shaft 23 (pilot cam 40). It is transmitted to the mechanism 36.

  That is, in the driving force transmission device 6, the torque based on the rotational difference between the front housing 22 and the inner shaft 23 is transmitted to the cam mechanism 36 by the operation of the pilot clutch 35, and the cam mechanism 36 is connected to the main cam 39 generated by the torque. Based on the rotational difference from the pilot cam 40, the main cam 39 is moved to the axial main clutch 34 side. That is, the cam mechanism 36 converts the torque based on the rotational difference between the front housing 22 and the inner shaft 23 transmitted through the pilot clutch 35 into an axial pressing force and amplifies it. When the main cam 39 presses the main clutch 34, the main clutch 34 is sandwiched between the bottom portion 24 and frictionally engaged, that is, the front housing 22 and the inner shaft 23 are coupled so as to transmit torque. It has become so. Therefore, in the present embodiment, the pilot clutch 35 and the cam mechanism 36 constitute a pressing force generating means.

  The pilot clutch 35 is configured as an electromagnetic clutch using the electromagnet 50 as a drive source. Specifically, the rear housing 27 is formed with an annular groove 51 that opens to the outside of the front housing 22 (on the side opposite to the front housing 22, the right side in FIG. 2). Is housed in. A driving current is supplied to the electromagnet 50 from the ECU 11 provided outside the driving force transmission device 6 through the power line 52. The rear housing 27 is provided with a cylindrical portion 27a extending axially from the inner peripheral portion thereof toward the front housing 22 side. The electromagnet 50 is connected to the rear housing by a ball bearing 53 provided on the cylindrical portion 27a. 27 (and the front housing 22) are rotatably supported.

  Further, in the cylinder of the front housing 22, an annular armature 54 is arranged in the axial direction at a position where the outer clutch plate 48 and the inner clutch plate 49 are sandwiched between the armature 54 and the rear housing 27. The spline is slidably fitted. The pilot clutch 35 is attracted to the electromagnetic force of the electromagnet 50 and moves so that the outer clutch plates 48 and the inner clutch plates 49 are sandwiched between the armature 54 and the rear housing 27, thereby The clutch plate 48 and the inner clutch plate 49 are frictionally engaged.

  As described above, the driving force transmission device 6 can control the operation of the pilot clutch 35 through the current supply to the electromagnet 50. The operation of the main clutch 34, that is, the torque that can be transmitted between the front housing 22 and the inner shaft 23 can be freely controlled through the operation of the pilot clutch 35.

Next, a pre-torque mechanism that frictionally engages the main clutch 34 when the pilot clutch 35 is not operated will be described.
The driving force transmission device 6 applies a pressing force to the main clutch 34 and frictionally engages the pilot clutch 35 when the pilot clutch 35 is not operated, and reduces the pressing force applied to the main clutch 34 as the main cam 39 approaches the main clutch 34. A pre-torque mechanism 61 is provided. In the present embodiment, as shown in FIG. 3, the pre-torque mechanism 61 includes a piston 62 as a second pressing member that presses the main clutch 34 from the axially opposite side of the main cam 39, and an elastic member that biases the piston 62. 63, and an interlocking member 64 that moves the main cam 39 and the piston 62 in an interlocking manner.

  More specifically, the piston 62 is formed in an annular shape and is disposed on the inner peripheral side of the contact portion 46. The elastic member 63 is provided between the bottom 24 and the piston 62. In the present embodiment, the elastic member 63 is formed of, for example, a coil spring, and a plurality (for example, four) of elastic members 63 are provided at equal intervals in the circumferential direction. A retaining ring 65 is provided on the inner periphery of the front housing 22 with the main clutch 34 interposed between the piston 62 and the piston 62. The main clutch 34 is pressed by the piston 62 so as to be sandwiched between the piston 62 and the retaining ring 65 to be frictionally engaged.

  In addition, the interlocking member 64 as a reducing means is configured such that either the main cam 39 or the piston 62 moves in conjunction with the axial movement of either the main cam 39 or the piston 62. Are linked. Specifically, the inner clutch plate 38 is formed with a through-hole 66 along the axial direction on the inner peripheral side of the sliding portion 38 a that slides with the outer clutch plate 37 in each inner clutch plate 38. A plurality of through holes 66 are formed at equal intervals in the circumferential direction (four in this embodiment), and each inner clutch plate 38 is disposed so that each through hole 66 is coaxially positioned. . The interlocking member 64 is formed in a columnar shape, and its base end (right side in FIG. 3) is embedded and fixed at a position corresponding to the through hole 66 in the main cam 39. The interlocking member 64 is inserted into each through hole 66, and the tip thereof is in contact with the piston 62 via the thrust bearing 67. As a result, the interlocking member 64 (main cam 39) presses the piston 62 while allowing relative rotation with the piston 62. Furthermore, in this embodiment, the interlocking member 64 is made of a rigid body such as iron, stainless steel, or resin, and is not deformed even when pressed by the main cam 39 or the piston.

  When the pilot clutch 35 is not operated, a first gap D1 is formed between the main cam 39 and the outer clutch plate 37 (main clutch 34) disposed on the cam mechanism 36 side. Yes. That is, the axial movement distance required until the main cam 39 applies a pressing force to the main clutch 34 is the first gap D1. Further, when the pilot clutch 35 is not in operation, a second clearance smaller than the first clearance D1 is provided between the outer clutch plate 37 (main clutch 34) disposed on the bottom 24 side and the contact portion 46. D2 is formed. That is, the moving distance of the main clutch 34 required until the pressing force of the main cam 39 acts on the contact portion 46 via the main clutch 34 is the second gap D2. Further, a third gap D3 larger than the first gap D1 is formed between the piston 62 and the bottom 24. That is, the axial distance until the piston 62 contacts the bottom 24 is the third gap D3. The elastic member 63 is elastically deformable to be larger than the first gap D1.

Next, the operation of the pre-torque mechanism 61 will be described.
As described above, when the pilot clutch 35 is not in operation, the main clutch 34 is pressed and frictionally engaged with the piston 62 so that a predetermined torque can be transmitted from the front housing 22 to the inner shaft.

  On the other hand, when current supply from the ECU 11 to the electromagnet 50 is started, the pilot clutch 35 is operated, and torque based on the rotational difference between the front housing 22 and the inner shaft 23 is applied to the cam mechanism 36 according to the frictional engagement force of the pilot clutch 35. Then, the main cam 39 starts to move in the axial direction. When the amount of axial movement of the main cam 39 increases as the current supplied to the electromagnet 50 increases, the main cam 39 moves only the piston 62 via the interlocking member 64 until the first gap D1 disappears. The elastic member 63 is pressed in the direction opposite to the urging direction. Therefore, the pressing force applied by the piston 62 to the main clutch 34 is reduced, the friction engagement force of the main clutch 34 is reduced, and the torque transmission capacity of the main clutch 34 is reduced.

  In a state where the main cam 39 is moved in the axial direction by not less than the second gap D2 and not more than the first gap D1 (see FIG. 4), the main clutch 34 is not pressed by the piston 62 and is not pressed by the main cam 39. Therefore, the torque transmission capacity of the main clutch 34 becomes zero. FIG. 4 shows a state in which the main cam 39 is moved in the axial direction by the first gap D1 or less. Accordingly, the torque transmission capacity of the driving force transmission device 6 is a value corresponding to the torque transmission capacity of the pilot clutch 35. When the current supplied to the electromagnet 50 is further increased from the state shown in FIG. 4, the main clutch 34 is pressed by the main cam 39 and frictionally engaged again, as shown in FIG. Accordingly, the torque transmission capacity of the main clutch 34 increases.

  Therefore, the driving force transmission device 6 of the present embodiment is configured to be able to change the torque transmission capacity in accordance with the current supplied to the electromagnet 50, as shown in FIG. Specifically, the torque transmission capacity of the main clutch 34 temporarily decreases as the current increases, and then increases, as indicated by the alternate long and short dash line. Further, the torque transmission capacity of the pilot clutch 35 monotonously increases as the current increases, as indicated by a two-dot chain line. Therefore, the torque transmission capacity of the driving force transmission device 6 is once lowered and increased thereafter as the current increases, as shown by the thick line. For this reason, pre-torque is applied to the main clutch 34 by the piston 62 even at the initial stage of occurrence of the wheel speed difference between the front wheel 10f and the rear wheel 10r, for example, when slip occurs when the vehicle 1 starts. A predetermined torque is distributed to the rear wheel 10r, and an increase in slip can be prevented to improve traction performance. Further, when the turning radius of the vehicle 1 is small, the current is supplied so that the main cam 39 moves in the axial direction by the second gap D2 or more and the first gap D1 or less, so that the driving force transmission device 6 For example, when the torque transmission capacity is reduced and, for example, the turning radius of the vehicle 1 is small, the tight corner braking phenomenon can be prevented and the running stability of the vehicle 1 can be improved.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The driving force transmission device 6 includes a piston 62 that presses the main clutch 34 in the axial direction from the opposite side of the main cam 39 in the axial direction, and the piston 62 that is connected to the main clutch 34 based on an increase in pressing force generated by the cam mechanism 36. And an interlocking member 64 that reduces the pressing force applied to the. Therefore, when the pilot clutch 35 is not operated, the main clutch 34 is frictionally engaged by being pressed by the piston 62 and can transmit a predetermined torque. Therefore, for example, when a slip occurs when the vehicle 1 starts, a predetermined torque is distributed to the rear wheel 10r even in the initial generation of the wheel speed difference, thereby preventing the slip from increasing and improving the traction performance. Can be achieved. In addition, the interlocking member 64 reduces the frictional force of the main clutch 34 by reducing the pressing force applied to the main clutch 34 by the piston 62 based on the increase in the pressing force generated by the cam mechanism 36. For example, when the turning radius of the vehicle 1 is small, the occurrence of a tight corner braking phenomenon can be prevented and the running stability of the vehicle 1 can be improved.

  (2) A through hole 66 is formed on the inner peripheral side of the sliding portion 38a in the inner clutch plate 38. The interlocking member 64 has a base end fixed at a position corresponding to the through hole 66 in the main cam 39, and is inserted into each through hole 66 so that a tip thereof contacts the piston 62 via a thrust bearing 67. . Accordingly, the main cam 39 moves in the axial direction toward the main clutch 34, whereby the pressing force applied by the piston 62 to the main clutch 34 can be reduced.

  (3) The front housing 22 is formed in a bottomed cylindrical shape, and an abutting portion 46 is formed in the outer peripheral edge of the bottom portion 24 of the front housing 22 so as to abut the main clutch 34 pressed by the main cam 39 in the axial direction. did. The piston 62 is disposed on the inner peripheral side of the contact portion 46 and is urged toward the main clutch 34 by an elastic member 63 provided between the piston 62 and the bottom portion 24. Therefore, since the piston 62 is disposed on the inner peripheral side of the contact portion 46, the driving force transmission device 6 can be prevented from being enlarged. Moreover, since the piston 62 is pressed by the elastic member 63 provided between the bottom part 24, the piston 62 can be pressed with a simple configuration.

  (4) When the pilot clutch 35 is not operated, the first gap D1 is formed between the main cam 39 and the main clutch 34, and is smaller than the first gap D1 between the contact portion 46 and the main clutch 34. A second gap D2 was formed. Further, a third gap D3 larger than the first gap D1 is formed between the piston 62 and the bottom 24, and the elastic member 63 is configured to be elastically deformable larger than the first gap D1. Therefore, the axial force of the main cam 39 can reduce the pressing force applied by the piston 62 to the main clutch 34, so that the tight corner braking phenomenon can be reliably prevented.

  (5) Since the interlocking member 64 is composed of a rigid body, it does not deform even when pressed by the main cam 39 or the piston 62, and the main cam 39 and the piston 62 move in the axial direction without changing the relative distance in the axial direction. Therefore, the pressing force applied by the piston 62 to the main clutch 34 in accordance with the axial movement of the main cam 39 can be reduced more efficiently than when the interlocking member 64 is made of an elastic material, for example. Accordingly, it is possible to reduce the distance that the main cam 39 moves in the axial direction in order to reduce the pressing force applied by the piston 62 to the main clutch 34, and it is possible to prevent the driving force transmission device 6 from being enlarged in the axial direction. .

In addition, you may implement the said embodiment in the following aspects.
In the above embodiment, the interlocking member 64 is embedded and fixed in the main cam 39. However, the interlocking member 64 is not limited thereto, and may be fixed to the main cam 39. For example, the main cam 39 and the interlocking member 64 are integrally formed. May be.

  In the above embodiment, the interlocking member 64 is fixed to the main cam 39 and is brought into contact with the piston 62 via the thrust bearing 67. However, the present invention is not limited to this, and the interlocking member 64 is fixed to the piston 62 and the thrust. You may make it contact | abut to the main cam 39 via the bearing 67. FIG.

In the above embodiment, a plurality of elastic members 63 are provided at equal intervals in the circumferential direction. However, the present invention is not limited to this, and one coil spring having substantially the same diameter as the piston 62 may be provided.
In the above embodiment, when the pilot clutch 35 is not in operation, the second gap D2 is made smaller than the first gap D1, the third gap D3 is made larger than the first gap D1, and the piston 62 By moving the main cam 39 in the axial direction, the main cam 39 is moved to the side opposite to the main clutch 34 in the axial direction larger than the first gap D1. However, the present invention is not limited to this, and the second gap D2 is equal to or smaller than the first gap D1 and the third gap D3 is equal to or larger than the first gap D1. What is necessary is just to make it move to the direction opposite to the main clutch 34 in the axial direction by the same distance as the axial distance of the gap D1. Even in this case, the torque transmission capacity of the main clutch 34 can be reduced to zero.

  Further, the second gap D2 is made larger than the first gap D1, and the piston 62 is moved in the axial direction of the main cam 39, so that the distance between the second gap D2 and the anti-main clutch 34 is smaller than the axial distance of the second gap D2. It may not be moved to the side. Even in this case, the torque transmission capacity of the main clutch 34 can be reduced.

  In the above embodiment, the outer clutch plates 37 are disposed at both axial ends of the main clutch 34. However, the present invention is not limited thereto, and inner clutch plates may be disposed at both axial ends. In this case, it is desirable to interpose a thrust bearing between the inner clutch plate 38 disposed on the bottom 24 side, the contact portion 46 and the piston 62, and the thrust bearing 45 may not be provided.

  In the above embodiment, the piston 62 and the elastic member 63 are provided on the bottom 24. However, the present invention is not limited to this, and a flange portion extending radially outward is formed at the end of the inner shaft 23 on the bottom 24 side. A piston 62 and an elastic member 63 may be provided. In this case, it is desirable to interpose a thrust bearing between the outer clutch plate 37 and the piston 62 disposed on the bottom 24 side.

  In the above-described embodiment, the torque transmission capacity of the driving force transmission device 6 is once decreased and then increased as the current supplied to the electromagnet 50 increases. The torque transmission capacity of the driving force transmission device 6 may be maximized during operation, and the torque transmission capacity may be decreased only by increasing the current.

In the above embodiment, the interlocking member 64 is made of a rigid material. However, the present invention is not limited to this, and the interlocking member 64 may be made of an elastic member such as a coil spring.
In the above embodiment, the pilot clutch 35 is configured as an electromagnetic clutch and current is supplied to the electromagnet 50. However, the present invention is not limited to this, and the pilot clutch 35 is operated by hydraulic pressure to control the current supplied to the hydraulic valve. The transmission torque may be controlled.

  In the above embodiment, the pressing force generating means is configured by the pilot cam 40 and the cam mechanism 36. However, the present invention is not limited to this, and for example, a driving force transmission for driving the main clutch 34 using a piston operated by hydraulic pressure as the first pressing member. The present invention may be applied to an apparatus.

  In the above embodiment, the interlocking member 64 is used as the reducing means. However, the present invention is not limited to this, and the pressing force applied to the main clutch 34 by the piston 62 based on the increase in the pressing force generated by the cam mechanism 36 is reduced. That's fine. For example, an electromagnet may be provided on the bottom 24 of the front housing 22 and the piston 62 may be attracted according to the supplied current.

  In the above embodiment, the driving force transmission device 6 is mounted on the vehicle 1 having the front wheel 10f as the main driving wheel.

The schematic block diagram of the vehicle provided with the driving force transmission apparatus. Sectional drawing of a driving force transmission device. The expanded sectional view of the driving force transmission device at the time of non-operation of a pilot clutch. The expanded sectional view of the driving force transmission device in the state where the pressing force is not acting on the main clutch by the operation of the pilot clutch. The expanded sectional view of the driving force transmission device in the state where the main clutch was pressed by the main cam by the operation of the pilot clutch. The wave form diagram which shows the relationship between the electric current supplied to an electromagnet, and torque transmission capacity.

Explanation of symbols

  6 ... Driving force transmission device, 22 ... Front housing, 23 ... Inner shaft, 24 ... Bottom, 34 ... Main clutch, 35 ... Pilot clutch, 36 ... Cam mechanism, 37 ... Outer clutch plate, 38 ... Inner clutch plate, 38a ... Sliding part 39 ... main cam 46 ... abutting part 62 ... piston 63 ... elastic member 64 ... interlocking member 66 ... through hole D1 ... first gap D2 ... second gap D3 ... first 3 gaps.

Claims (5)

A cylindrical first rotating member, a shaft-like second rotating member coaxially disposed in the first rotating member, an outer clutch plate that rotates integrally with the first rotating member, and the second rotating member And clutch mechanisms in which inner clutch plates that rotate integrally with each other, pressing force generating means for generating axial pressing force, and axial movement according to the pressing force generated by the pressing force generating means A driving force transmission device including a first pressing member that presses the clutch mechanism, and configured to be able to change a torque transmission capacity between the first rotating member and the second rotating member;
A second pressing member that axially presses the clutch mechanism from an axially opposite side of the first pressing member;
A driving force transmission device comprising: a reducing means for reducing the pressing force applied to the clutch mechanism by the second pressing member based on an increase in the pressing force generated by the pressing force generating means. In the inner clutch plate, a through hole is formed on an inner peripheral side of a sliding portion that slides with the outer clutch plate in the inner clutch plate,
The reducing means is inserted through the through-hole, and any one of the first pressing member and the second pressing member is moved in the axial direction of either the first pressing member or the second pressing member. The driving force transmission device according to claim 1, wherein the driving force transmission device is an interlocking member that moves the other interlockingly. The first rotating member is formed in a bottomed cylindrical shape,
On the outer peripheral edge of the bottom portion of the first rotating member, an abutting portion with which the clutch mechanism pressed against the first pressing member abuts is formed extending in the axial direction.
The second pressing member is disposed on the inner peripheral side of the contact portion, and is biased toward the clutch mechanism by an elastic member provided between the second pressing member and the bottom portion. The driving force transmission device according to claim 1 or 2, characterized in that When the pressing force generating means is not in operation,
A first gap is formed between the first pressing member and the clutch mechanism,
A second gap that is equal to or smaller than the first gap is formed between the contact portion and the clutch mechanism,
Between the second pressing member and the bottom, a third gap that is equal to or greater than the first gap is formed,
The driving force transmission device according to claim 3, wherein the elastic member is configured to be elastically deformable beyond the first gap.   The driving force transmission device according to claim 2, wherein the interlocking member is made of a rigid body.

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