JP4309781B2 - Power transmission mechanism for four-wheel drive vehicles - Google Patents

Description

  In the present invention, a power unit having a prime mover and a transmission is arranged between a front wheel and a rear wheel, and a front end portion of a power take-off shaft of the transmission is linked to an input shaft of a front wheel differential through a front wheel propeller shaft. It relates to the power transmission mechanism of a four-wheel drive vehicle in which the rear end portion of the power take-off shaft is interlocked with the input shaft of the final reducer for rear wheels via the rear wheel propeller shaft. The present invention relates to a power transmission mechanism suitable for a suspension type four-wheel drive vehicle.

  FIG. 6 shows an example of a power transmission mechanism of a conventional four-wheel independent suspension type four-wheel drive vehicle (see Patent Document 1, etc.). In FIG. 6, a pair of left and right front wheels 101 and a pair of left and right rear wheels are shown. 102 are independently suspended by a suspension arm 103 and a shock absorber (not shown) that can swing vertically, and a power unit P comprising a transmission such as a prime mover and a torque converter is provided between the front wheel 101 and the rear wheel 102. Is installed.

  The front wheel differential 106 and the rear wheel final speed reducer 107 are arranged at the center of the vehicle width, and the power take-off shaft 110 connected to the output portion of the power unit P is displaced from the center of the vehicle width to the left and the center line of the vehicle width. It is arranged substantially parallel to C. The front end portion of the power take-out shaft 110 is connected to the input shaft 114 of the front wheel differential 106 through a front wheel propeller shaft 112 disposed substantially parallel to the vehicle width center line C, and the rear end portion of the power take-out shaft 110 is connected. Is connected to the input shaft 118 of the final reduction gear 107 for rear wheels via a rear wheel propeller shaft 115 inclined with respect to the vehicle width center line C.

  The power unit P is disposed rearward of the center between the front and rear wheels 101 and 102, so that the distance between the rear end portion of the power take-off shaft 110 and the rear wheel final speed reducer 107 is the same as that of the power take-out shaft 110. The distance between the front end and the front wheel differential 106 is shorter.

  The input shaft 118 of the rear wheel final reduction gear 107 is arranged in parallel to the vehicle width center line C, and the rear wheel propeller shaft 115 has front and rear end portions thereof via cardan joints (universal joints) 120 and 121, respectively. The power take-out shaft 110 and the input shaft 118 are connected to the rear end portion of the power take-out shaft 110 with a certain bending angle, and are arranged in a Z shape together with the power take-out shaft 110 and the input shaft 118 as viewed from above.

  The cardan joints 120 and 121 at the front and rear of the propeller shaft 115 for the rear wheel are individually non-constant joints, but are bent at substantially the same angle, so that the speed change cancels each other during one rotation, and the power is taken out. Transmission between the shaft 110 and the input shaft 118 is performed at a substantially constant speed.

In the four-wheel independent four-wheel drive vehicle, the front-wheel differential gear 106 and the rear-wheel final reduction gear 107 are arranged at the center of the vehicle width as described above, so that each suspension arm (A-shaped arm). 103 can be made equal in length to the left and right, and it is possible to prevent the vehicle width from becoming large, to secure a long suspension stroke while suppressing changes in the tread, and to improve the ride comfort.
Japanese Patent Application Laid-Open No. 2001-301477.

  The power transmission mechanism shown in FIG. 6 includes a power take-off shaft 110 arranged in parallel with the vehicle width center line C and an input shaft 118 of the rear-wheel final speed reducer 107 as one inclined rear-wheel propeller shaft. 115, the cardan joints 120 and 121 are bent in opposite directions to each other, so that the bending angles (intersection angles) of the joints 120 and 121 are increased, and the rotation of the cardan joints 120 and 121 is performed. As the fluctuation increases, the power loss to the rear wheel 102 increases, and it is necessary to take measures for improving the life of the cardan joints 120 and 121.

  Further, if the power unit P is disposed rearward of the central portion between the front and rear wheels 101 and 102, the distance between the front and rear for arranging the propeller shaft 115 for the rear wheel in the inclined posture is shortened, and the cardan joint This may be one of the factors that increase the bending angle of 120 and 121.

(Object of invention)
An object of the present invention is to provide a power transmission mechanism for a four-wheel drive vehicle capable of maintaining the compactness of the vehicle width and the ride comfort, and at the same time extending the life of the joint and reducing the power loss to the rear wheels. That is.

  In order to solve the above problems, the present invention provides a power unit having a prime mover and a transmission between a front wheel and a rear wheel of a four-wheel independent suspension type, and a power take-off shaft of the transmission is substantially parallel to a vehicle width center line. The front end of the power take-off shaft is linked to the input shaft of the front wheel differential via the front wheel propeller shaft, and the rear end of the power take-off shaft is connected to the rear wheel via the rear wheel propeller shaft. In the power transmission mechanism of a four-wheel drive vehicle that is linked to the input shaft of the final reduction gear for the vehicle, the differential for the front wheel and the final reduction gear for the rear wheel are each arranged in the center of the vehicle width, and the power take-out shaft is in the center of the vehicle width The input shaft of the front wheel differential and the propeller shaft for the front wheel are arranged substantially parallel to the vehicle width center line and on the same axis as the power take-off shaft. The input shaft of the reducer is arranged in a posture in which the front end portion is inclined from the vehicle width center side to the power take-off shaft side, Propeller shaft for wheel, with respect to the vehicle width center line, are arranged at a small inclination angle than the input shaft of the rear wheel final reduction gear. In short, the rear end of the power take-off shaft of the transmission displaced to the left or right from the vehicle width center line and the rear wheel final speed reducer arranged on the vehicle width center line are in the same direction in two stages. The rear wheel propeller shaft inclined to the rear wheel and the rear wheel final reduction gear input shaft are connected. In other words, the rear wheel propeller shaft and the input shaft are "M-shaped".

  The front and rear end portions of the rear wheel propeller shaft are preferably connected to the power take-off shaft rear end portion of the transmission and the input shaft of the rear wheel final speed reducer by a cardan joint.

  The bending angle between the power take-off shaft and the rear wheel propeller shaft and the bending angle between the rear wheel propeller shaft and the input shaft of the rear wheel final speed reducer are preferably set to be equal.

  Preferably, the power unit is moved further forward than the center between the front and rear wheels so that the distance between the power take-off shaft and the rear wheel final reduction gear is longer than the distance between the power take-out shaft and the front wheel differential. Deploy.

  With regard to the structure of the final reduction gear for rear wheels, a brake device can be provided on the input shaft in an inclined posture, and the brake device is preferably a wet multi-plate brake device, and the casing of the wet multi-plate brake device Is preferably formed integrally with the casing of the rear wheel final reduction gear.

(1) By arranging the front wheel differential and the rear wheel final reduction gear at the center of the vehicle width, the suspension arms for the front and rear wheels can be set to be equal in length to the left and right, and the vehicle width is compact. As well as improving riding comfort, the following effects are also achieved.

(2) A rear-wheel propeller shaft is disposed between the rear end portion of the power take-off shaft of the transmission displaced from the vehicle width center line to one of the left and right sides, and the rear-wheel final speed reducer disposed on the vehicle width center line. And the input shaft of the rear wheel final reduction gear are connected in a two-stage inclined state in an M shape, so that the bending angle of the joint portion at the front and rear ends of the rear wheel propeller shaft is kept small, and the rear wheel propeller The rotational fluctuation of the shaft can be kept low, the life can be extended and the vibration can be reduced by suppressing the wear of the joint, and the reduction of the power loss to the rear wheel can also be suppressed.

(3) Especially when a cardan joint is used as the joint, it is possible to reduce the component cost while achieving the effects of the items (1) and (2).

(4) The bending angle between the power take-off shaft and the rear wheel propeller shaft is made equal to the bending angle between the rear wheel propeller shaft and the input shaft of the rear wheel final speed reducer. And offset the fluctuations in angular velocity that occur in both joints, and the rear axle can be rotated at a constant speed.

(5) If the power take-off shaft is arranged in front of the center between the front and rear wheels so that the distance to the rear wheel final reduction gear is longer than the distance to the front wheel final reduction gear, A large distance in the front-rear direction of the rear-wheel propeller shaft to be arranged can be secured, whereby the inclination angle of the rear-wheel propeller shaft can be further reduced, and power loss can be reduced.

(6) If the brake device is provided on the input shaft of the inclined posture of the rear wheel final reduction gear, the free space on the front side of the rear wheel final reduction gear can be used effectively for brake arrangement. In particular, in a structure in which the power unit is arranged closer to the front and the distance between the power unit and the rear wheel final reduction gear is large, a sufficient brake arrangement space can be secured. Moreover, the cooling effect can also be improved by using the traveling wind by being arranged on the front side of the rear wheel final reduction gear.

(7) When the wet multi-plate brake device is provided as the brake device, the radial dimension of the brake device, particularly the vertical dimension, can be arranged compactly, and a wide space is ensured between the brake device and the ground. The minimum ground clearance can be maintained.

(8) When the casing of the wet multi-plate brake device is integrally formed with the casing of the final reduction gear for rear wheels, the casing of the brake device can be simplified, and the lubricating oil and the wet multi-plate of the final reduction gear It can be used in common with the lubricating oil of the mold brake, eliminating the need for trouble in the maintenance of the lubricating oil system. In addition, while the rear wheel final reduction gear is centrally arranged, the height of the rear wheel final reduction gear from the ground can be maintained high.

  1 to 5 show four-wheel drive vehicles for riding on rough terrain to which the present invention is applied. Embodiments of the present invention will be described below with reference to the drawings.

[Overall layout of a four-wheel drive vehicle]
In FIG. 2 showing the right side view of the entire four-wheel drive vehicle, a pair of left and right front wheels 1 arranged at the front end of a frame F extending in the front-rear direction is a pair of upper and lower suspension arms (only the lower A-shaped arm is shown). 3 and the shock absorber 5 are suspended so as to be independently swingable in the vertical direction.

  A pair of left and right rear wheels 2 arranged at the rear end of the frame F is also a suspension mechanism comprising a pair of upper and lower suspension arms (only the lower A-shaped arm is shown) 7 and a shock absorber 8, similar to the front wheel 1. Thus, each is suspended so as to be independently swingable in the vertical direction.

  Between the front wheel 1 and the rear wheel 2, a power unit P including a prime mover 10, a V-belt type automatic transmission 11, a gear type auxiliary transmission 12, and the like is disposed. The power unit P includes front, rear wheels 1, It is located closer to the front than the center between the two. On the upper part of the frame F, a riding-type seat 14, a bar-type handle device 15 and the like are arranged.

  FIG. 1 is a plan view of a power transmission mechanism of a four-wheel drive vehicle. A front wheel differential 20 is arranged between the left and right front wheels 1 at the center of the vehicle width, and left and right outputs in the front wheel differential 20 are shown. The shaft portion is connected to one end portion of the left and right front wheel drive shafts 23 via a constant velocity joint 22, and the other end portion of each front wheel drive shaft 23 is connected to the front axle of each front wheel 1 via a constant velocity joint 24. It is connected. The left and right front wheel drive shafts 23 are formed to be equal in length and are arranged substantially symmetrically with respect to the vehicle width center line C. The left and right front wheel suspension arms 3 are also formed to be equal in length to the left and right. The vehicle width center line C is arranged substantially symmetrically. The input shaft 25 of the front wheel differential 20 is provided in parallel to the vehicle width center line C at a position displaced on the right side from the vehicle width center by a distance d (on the horizontal axis O1).

  Between the left and right rear wheels 2, a rear wheel final reduction gear 30 is disposed in the center of the vehicle width, and the left and right rear wheel output shaft portions 31 of the rear wheel final reduction gear 30 have constant velocity joints 32 respectively. The other end of each rear wheel drive shaft 33 is connected to the rear axle of each rear wheel 2 via a constant velocity joint 34. The left and right rear wheel drive shafts 33 are formed to be equal in length and are arranged symmetrically with respect to the vehicle width center line C, and the left and right suspension arms 7 are also formed to be equal in length to the left and right. It is arranged symmetrically with respect to the vehicle width center line C. The input shaft 35 of the rear wheel final reduction gear 30 is inclined so that the rear end small bevel gear (pinion gear) 37 is slightly displaced to the left with respect to the vehicle width center line C, and the front end portion comes to the right. ing.

[V-belt type automatic transmission]
The V-belt type automatic transmission 11 is provided on the right side of the prime mover 10, and is connected to a drive train 47 connected to a lateral crankshaft of the prime mover 10 and a transmission input shaft of the gear type sub-transmission 12. It consists of a driven adjustment gear 48 and a V-belt 49 wound around both adjustment gears 47, 48, and automatically increases from the low state (maximum reduction ratio state) at the start of operation as the engine speed increases. The gear ratio is shifted to the side (high speed side), and the reduction ratio can be automatically increased by increasing the load from the wheel side.

  The V-belt type automatic transmission 11 is covered with a belt cover 13, a cooling air inflow hole 16 is formed at the front end of the belt cover 13, and a cooling air discharge hole 17 is formed at the rear end of the belt cover 13. A suction fan provided on the rear surface of the vehicle 47 sucks external air from the cooling air inlet hole 16, cools the V-belt type automatic transmission 11, and discharges it from the rear cooling air outlet hole 17. .

[Power transmission system from the power unit to the front wheel differential and the rear wheel final reduction gear]
A power take-out shaft 39 extending in the front-rear direction and parallel to the vehicle width center line C is supported at the lower end of the power unit P. The power take-out shaft 39 is displaced to the right from the vehicle width center line C, It is disposed on the same axis O1 as the input shaft 25 of the front wheel differential 20 and is linked to the shift output shaft 43 of the gear-type auxiliary transmission 12 via a reduction mechanism comprising large and small bevel gears 41 and 42. Yes.

  The front end portion of the power take-out shaft 39 projects forward from the front end of the power unit P (the front end of the prime mover 10), and the input shaft 25 of the front wheel differential 20 and the front end portion of the power take-out shaft 39 are in the vehicle width center line. Parallel to C, the shafts 25 and 39 are connected to the front wheel propeller shaft 26 disposed on the coaxial core O1. The connecting portion between the front and rear end portions of the propeller shaft 26 for the front wheel and the shafts 25 and 39 is not a cardan joint because the three shafts 25, 26 and 39 are aligned on the same axis O 1. Are connected by simple coaxial spline joints 27 and 28.

  FIG. 3 is an enlarged horizontal cross-sectional view of the rear wheel power transmission system. The rear end portion of the power take-out shaft 39 protrudes rearward from the rear end of the power unit P (rear end of the auxiliary transmission 12), and is inclined. The rear wheel propeller shaft 36 is connected to the input shaft 35 of the rear wheel final speed reducer 30 in the inclined posture. The longitudinal distance between the rear end portion of the power take-out shaft 39 and the rear wheel final reduction gear 30 is set to be longer than the front-rear direction distance between the front end portion of the power take-out shaft 39 and the front wheel differential 20 (FIG. 1). ing. Particularly in this embodiment, the distance in the front-rear direction between the rear end portion of the power take-out shaft 39 and the input shaft 35 of the rear wheel final reduction gear 30 is also the same as that of the front end portion of the power take-out shaft 39 and the front wheel differential 20 (FIG. 1). ) Is set to be longer than the distance in the front-rear direction from the input shaft 25.

  As described above, the input shaft 35 of the rear wheel final reduction gear 30 has the rear end small bevel gear 37 slightly displaced to the left with respect to the vehicle width center line C, and the front end portion of the input shaft 35 has a vehicle width. It inclines so that it may come to the right with respect to the center line C. The inclination angle θ1 to the right with respect to the vehicle width center line C is set to 11 degrees, for example. In other words, the input shaft 35 is inclined at an angle of θ2 = 79 degrees with respect to the axis O3 of the rear wheel hollow shaft 61 to which the large bevel gear 38 is fixed.

  The front end portion of the rear wheel propeller shaft 36 is connected to the rear end portion of the power take-off shaft 39 via a cardan joint (universal joint) 40, and the rear end portion of the rear wheel propeller shaft 36 is connected to the rear wheel via a cardan joint 46. It is connected to the input shaft 35 of the final reduction gear 30 for use. The rear wheel propeller shaft 36 is inclined with respect to the vehicle width center line C so that the front end portion of the rear wheel propeller shaft 36 comes to the right, that is, in the same direction as the inclination direction of the input shaft 35. The inclination angle θ3 of the rear wheel propeller shaft 36 with respect to the vehicle width center line C is set smaller than the inclination angle θ1 of the input shaft 35. That is, the power take-out shaft 39 of the transmission 12 and the inclined input shaft 35 are bent in two steps in the same direction at the center portions A1 and A2 of the front and rear cardan joints 40 and 46, so-called M It has a configuration of shape. The inclination angle θ3 of the rear wheel propeller shaft 36 with respect to the vehicle width center line C is set to a half (for example, 5.5 °) of the inclination angle θ1 of the input shaft 35, and therefore, the front bending center portion A1 is set. The bending angle θ3 at is the same as the bending angle (θ1−θ3) at the rear bending center portion A2, which is 5.5 degrees.

  The front and rear boss members 40a and 40b constituting the front cardan joint 40 are spline-coupled to the rear end portion of the power take-out shaft 39 and the front end portion of the rear wheel propeller shaft 36, respectively. The front and rear boss members 46a and 46b constituting the rear-side cardan joint 46 are spline-coupled to the rear wheel propeller shaft 36 and the input shaft 35, respectively, but the front boss member 46a extends forward and extends rearward. The propeller shaft 36 is fitted to the rear end of the propeller shaft 36 so as to be movable in the axial direction, and a coil spring 44 is contracted in the front boss member 46a so as to be extendable in the axial direction. Due to the elastic force of the coil spring 44, the shafts 36 and 35 are always urged away from each other to prevent the rear wheel propeller shaft 36 from playing in the axial direction, and the rear wheel final speed reducer. The rear wheel propeller shaft 36 can be attached and detached without removing the 30 from the frame F.

[Rear wheel final reduction gear and brake device]
In FIG. 3, the rear wheel final reduction gear 30 is composed of the small bevel gear (pinion gear) 37 and a large bevel gear (ring gear) 38 that meshes with the small bevel gear 37. As described above, the wet multi-plate friction brake device 50 is provided on the input shaft 35 that protrudes obliquely forward to the right. The casing of the rear wheel final reduction gear 30 and the casing of the brake device 50 are integrally formed, and are attached to and detached from the housing 51 and the right side cover 52 that surround both the bevel gears 37 and 38, and the front end portion of the housing 51. The front end brake cover 53 is freely attached. The large bevel gear 38 is set to an acute angle (for example, about 79 °) corresponding to the input shaft 35 being disposed in an inclined state.

  The input shaft 35 is rotatably supported by the front end brake cover 53 and the housing 51 by front and rear bearings 58 disposed in the brake chamber 55, and the small bevel gear 37 protrudes into the speed reducer chamber 56 and the rear end thereof is A boss 51 a formed in the housing 51 is supported via a bearing 59. That is, the small bevel gear 37 is supported at both front and rear ends.

  The large bevel gear 38 is disposed on the right side with respect to the small bevel gear 37 and is fixed (screwed) to the outer periphery of the hollow shaft 61 extending in the left-right direction. The large bevel gear 38 and the hollow shaft 61 are rotatably supported by the housing 51 and the right side cover 52 via a pair of left and right bearings 62. A pair of left and right rear wheel output shaft portions 31 are spline-fitted to the inner peripheral spline of the hollow shaft 61, and both rear wheel output shaft portions 31 protrude from the housing 51 and the right side cover 52 to the left and right, respectively. As described above, it is connected to the left and right rear wheel drive shafts 33 via the constant velocity joint 32.

  As described above, the brake device 50 corresponds to the input shaft 35 of the rear wheel final reduction gear 30 being inclined to the right side by an angle θ1 (11 degrees) with respect to the vehicle width center line C. The front and rear end walls are formed in a posture inclined by θ1 (11 degrees) in the same direction (right direction) as the input shaft 35 with respect to a plane M perpendicular to the vehicle width center line C.

  The wet multi-plate brake device 50 is alternately arranged in the axial direction with respect to each friction plate 64 and a plurality of friction plates 64 that are spline-fitted to the outer peripheral spline of the input shaft 35 so as to be movable in the input axial direction. And a plurality of separate plates 66 engaged with the inner peripheral groove 65 of the front end brake cover 53 so as to be movable in the axial direction, and an annular member disposed between the foremost separate plate 66 and the rear surface of the front end brake cover 53. It comprises a pressure plate 67, a steel ball 68 of a brake operation cam mechanism, and the like. The pressure plate 67 is rotatably supported by a boss formed on the front end brake cover 53, and a plurality of wedge grooves 69 are formed on the front end surface at equal intervals in the circumferential direction. A steel ball 68 that extends in a circular arc shape in the circumferential direction and has a groove depth that becomes shallower toward one side in the circumferential direction is engaged with the wedge groove 69 and embedded in the rear recess 70 of the front end brake cover 53. By combining them, a brake operation cam mechanism is formed.

  A protrusion 67a for operation is formed on the outer peripheral surface of the pressure plate 67, and a brake operating lever 71 is engaged with the protrusion 67a. The brake operating lever 71 is fixed to a lever shaft 72. The lever shaft 72 has a front end. A brake operation such as a brake operation pedal or a brake operation lever is supported by the brake cover 53 and the housing 51 while projecting forward from the front end brake cover 53 and via an operation force transmission mechanism such as a wire transmission mechanism (not shown). It is linked to the department.

  That is, when the lever shaft 72 and the brake operating lever 71 are rotated through the wire transmission mechanism by the brake operation of the brake operation unit, the pressure plate 67 is rotated from the state of FIG. The pressure plate 67 is moved rearward by the cam action between the pressure groove 67 and the wedge groove 69, and both the plates 64 and 66 are clamped between the pressure plate 67 and the front end surface of the housing 51 to brake the input shaft 35. ing.

[Brake cooling and lubrication system]
As a device for cooling the wet type multi-plate brake device 50, basically, a method of circulating the lubricating oil stored in the final reduction gear chamber 56 and the brake chamber 55 is employed. In order to promote heat dissipation from the oil, the traveling wind and the exhausted air from the V-belt type automatic transmission 11 can be actively used.

  4 shows a longitudinal side view (IV-IV cross section of FIG. 3) of the rear wheel final reduction gear 30 and the wet multi-plate brake device 50. The friction plate 64 and the separate plate 66 are outside the large bevel gear 38. The diameter is smaller than the diameter. The lower end of the front end brake cover 53 and the lower end of the front end of the housing 51 are formed with recesses 77 and 78 that extend in the vehicle width direction, and these recesses 77 and 78 provide capacity to the lower end of the brake chamber 55. A large oil reservoir 79 is formed. The oil reservoir 79 communicates with the lower portion of the final reduction gear chamber 56 via a lower oil passage 76.

  On the other hand, the shape of the rear half of the housing 51 is formed in an arc shape so as to surround the outer peripheral end of the large bevel gear 38 with a slight gap therebetween, thereby increasing the ground height of the lower end of the housing 31. Secured. In addition, an oil passage 80 is formed at the upper end portion of the front half of the housing 51 to communicate the upper end portion of the final reduction gear chamber 56 and the upper end inner peripheral groove portion 65 in the brake chamber 55.

  Between the front surface of the pressure plate 67 and the rear surface of the front end brake cover 53, an oil passage 81 communicating with the inner circumferential groove portion 65 and communicating with the space portion on the inner circumferential side from the separate plate 66 is formed. Oil holes 83 are formed in the inner peripheral side portions of 64.

  FIG. 5 is a cross-sectional view taken along the line VV of FIG. 4. A plurality of oil holes 83 of each friction plate 64 are formed at equal intervals in the circumferential direction, and the oil reservoir 79 at the lower end is wide in the vehicle width direction. It is formed to ensure a large storage capacity.

[Brake cooling device using exhaust air from V-belt type automatic transmission]
In FIG. 2, an exhaust air guide 85 is connected to the cooling air exhaust hole 17 formed at the rear end of the belt cover 13. The exhaust air guide 85 extends rearward and rises upward, and then continues to the frame. While entering F, the vehicle descends and reaches the vicinity of the front end brake cover 53 of the wet multi-plate brake device 50 as shown in FIG.

  In FIG. 3, the rear end portion of the wind exhaust guide (pipe) 85 opens obliquely from the right front toward the front end brake cover 53, and a choke portion (throttle portion) 86 is formed to increase the wind exhaust speed. Furthermore, an air ejector is configured by providing a tapered cylindrical mixing tube 87 with a gap in the radial direction on the outer periphery of the choke portion 86, thereby taking in the surrounding air and increasing the air volume. The temperature is reduced.

[Transmission of driving power]
In FIG. 1, the power output from the crankshaft of the prime mover 10 is transmitted to the gear-type auxiliary transmission 12 via the V-belt type automatic transmission 11, and the power is output from the transmission output shaft 43 via the bevel gears 41 and 42. It is transmitted to the take-out shaft 39.

  The power take-out shaft 39 is transmitted from the front end portion to the front wheel propeller shaft 26 through the joint 28, and the power take-out shaft 39 is transmitted from the rear end portion to the rear wheel propeller shaft 36 through the cardan joint 40.

  The power transmitted to the front-wheel propeller shaft 26 is decelerated in the front-wheel differential 20 and passes through the differential mechanism, and the left and right constant velocity joints 22, the front wheel drive shaft 23, and the constant velocity joint 24 Is transmitted to the front wheel (front axle) 1.

  In FIG. 3, the rear end portion of the power take-out shaft 39 is transmitted to the rear wheel propeller shaft 36 in an inclined posture via the front cardan joint 40, and the rear end portion of the rear wheel propeller shaft 36 is rearward from the rear end portion. It is transmitted to the input shaft 35 in the inclined posture of the rear wheel final reduction gear 30 via the rear cardan joint 46, and the direction is changed at the same time between the small bevel gear 37 and the large bevel gear 38, and the speed is reduced. It is transmitted from the shaft 61 to the left and right output shaft portions 31, and is transmitted to the left and right rear wheel drive shafts 33 via the constant velocity joint 32.

  As shown in FIG. 3, in the power transmission path from the power take-out shaft 39 to the rear wheel final reduction gear 30, an angular velocity change occurs in the front cardan joint 40, and the rear wheel propeller shaft 36 varies in rotation. The change in angular velocity caused by the front cardan joint 40 is canceled by the rear cardan joint 46 bent at the same bending angle as the joint 40, and the input shaft 35 rotates at a constant speed. In addition, the inclination angle θ1 of the input shaft 35 with respect to the power take-out shaft 39 is equally distributed in the two bent portions A1 and A2 that are bent in the same direction, whereby the bent portions A1 and A2 are bent. Since the bending angle is kept small (5.5 degrees), changes in angular velocity and rotational fluctuations at the bent portions A1 and A2 can be kept small, and generation of wear and mechanical noise can be reduced.

[Brake cooling]
In FIG. 4, the lubricating oil in the oil reservoir 79 formed below the wet multi-plate brake device 50 is swept upward in the direction of arrow R by the rotation of the large bevel gear 38, and passes through the oil passage 80 at the upper end. It passes through the front groove portion 65 and cools the outer peripheral side of the separation plate 66. Subsequently, the pressure plate 67 passes through the oil passage 81 on the front side of the pressure plate 67, cools the pressure plate 67, enters the inner peripheral side of the separate plate 66, and cools the friction plate 64 while passing through the oil holes 83 of the friction plate 64. Return to reservoir 79.

  Thus, since the lubricating oil circulates in the final reduction gear chamber 56 and the entire brake chamber 55, a wide heat radiation area can be secured for the final reduction gear 30 and the brake device 50 as a whole, and the cooling effect of the brake device 50 is improved. To do. Further, since the oil reservoir 79 is formed in the brake chamber 55 disposed on the front side of the rear wheel final reduction gear 30, the lubricating oil in the brake chamber 55 and the lubricating oil in the oil reservoir 79 are caused by the traveling wind from the front. To effectively cool.

  Further, in FIG. 3, the exhaust air sent from the belt cover 13 through the exhaust air guide 85 increases the speed at the choke portion 86 and sucks outside air through the mixing pipe 87 to increase the speed and air volume in the front end. It is applied to the brake cover 53, thereby promoting the heat dissipation action.

  Further, since the front end brake cover 53 is inclined with respect to the plane M perpendicular to the vehicle width center line C, the traveling wind from the front smoothly flows from the left to the right on the front surface of the front end brake cover 53, This also increases the cooling effect.

  The exhaust air guide 85 has a rising portion formed between the cooling air exhaust hole 17 of the belt cover 13 and the rear end choke portion 86 as shown in FIG. 2, so that the choke portion 86 enters the belt cover 13. Water can be prevented from entering.

[Other Embodiments of the Invention]
(1) In the above embodiment, as shown in FIG. 2, the power take-out shaft 39 and the input shaft 35 of the rear-wheel final reduction gear 30 are arranged in substantially the same horizontal plane. The present invention can be applied even when the input shaft 35 of the final reduction gear 30 has a height difference. For example, when the power take-out shaft 39 in FIG. 2 is arranged at a position higher than the input shaft 35 of the rear wheel final reduction gear 30, the rear wheel propeller shaft 36 and the input shaft 35 are viewed from above. The input shaft 35 is inclined so as to be lifted forward when viewed from the side, and the rear wheel propeller shaft 36 is also lifted up from the input shaft 35. Inclined forward at a half angle.

  As a result, even when the power take-out shaft 39 and the input shaft 35 of the rear wheel final reduction gear 30 have a height difference, the same effect as in the above embodiment can be obtained.

(2) The vehicle to which the present invention is applied is not limited to a four-wheel drive vehicle for running on rough terrain, and can also be applied to other four-wheel drive vehicles.

(3) It is also possible to apply the present invention to a four-wheel drive vehicle equipped with a two-wheel drive / four-wheel drive switching mechanism by dividing the power take-off shaft into two front and rear.

The present invention can be applied not only to the riding type rough terrain four-wheeled vehicle but also to other four-wheel independently suspended four-wheeled vehicles such as work vehicles.

It is a top view of the power transmission mechanism of the four-wheel drive vehicle to which this invention is applied. It is a right view of the four-wheel drive vehicle of FIG. It is a horizontal cross-section enlarged view of the final reduction gear for rear wheels and the wet multi-plate brake device. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is VV sectional drawing of FIG. It is a top view of the power transmission mechanism of the conventional four-wheel independent suspension type four-wheel drive vehicle.

Explanation of symbols

1 Front Wheel 2 Rear Wheel 3 Front Wheel Suspension Arm 5 Front Wheel Shock Absorber 7 Rear Wheel Suspension Arm 10 Motor 11 V-belt Automatic Transmission 12 Gear Auxiliary Transmission 13 Belt Cover 20 Front Wheel Differential 23 Front Wheel Drive Shaft 25 Front Wheel Input shaft 26 for front wheel Propeller shaft 30 for rear wheels Final reduction gear 31 for rear wheels Output shaft 33 for rear wheels Rear wheel drive shaft 35 Input shaft 36 for final reduction gears for rear wheels Rear wheel propeller shafts 37 and 38 Rear wheels Bevel gear 39 for final reducer for power supply Power take-off shaft 40, 46 Cardan joint 50 Wet multi-plate brake device P Power unit

Claims (7)

A power unit having a prime mover and a transmission is arranged between the front and rear wheels of the four-wheel independent suspension type, the power take-off shaft of the transmission is arranged substantially parallel to the vehicle width center line, and the front end of the power take-off shaft is The front wheel propeller shaft is linked to the input shaft of the front wheel differential, and the rear end of the power take-off shaft is linked to the rear wheel propeller shaft via the rear wheel propeller shaft. In the power transmission mechanism of a four-wheel drive vehicle,
A differential for front wheels and a final reduction gear for rear wheels are arranged in the center of the vehicle width,
Displace the power take-off shaft from the vehicle width center line to the left or right side,
The input shaft of the front wheel differential and the propeller shaft for the front wheel are arranged substantially parallel to the vehicle width center line and on the same axis as the power take-off shaft,
The rear wheel final reduction gear input shaft and the rear wheel propeller shaft are both arranged in a posture in which the front end portion is inclined from the vehicle width center side to the power take-off shaft side,
The four-wheel drive vehicle characterized in that the inclination angle θ3 of the rear wheel propeller shaft with respect to the vehicle width center line is set smaller than the inclination angle θ1 of the input shaft of the rear wheel final speed reducer with respect to the vehicle width center line Power transmission mechanism.   The front end and the rear end of the rear-wheel propeller shaft are connected to a power take-off shaft of the transmission and an input shaft of the rear-wheel final speed reducer by a cardan joint, respectively. Power transmission mechanism for four-wheel drive vehicles.   The bending angle between the power take-out shaft and the rear wheel propeller shaft is equal to the bending angle between the rear wheel propeller shaft and the input shaft of the rear wheel final speed reducer. A power transmission mechanism for a four-wheel drive vehicle according to claim 1 or 2.   The power unit is arranged closer to the front than the center between the front and rear wheels so that the distance between the power take-off shaft and the rear wheel final reduction gear is longer than the distance between the power take-out shaft and the front wheel differential. A power transmission mechanism for a four-wheel drive vehicle according to any one of claims 1 to 3.   The power transmission mechanism for a four-wheel drive vehicle according to any one of claims 1 to 4, wherein a brake device is provided on the input shaft of the inclined posture of the rear wheel final reduction gear.   6. The power transmission mechanism for a four-wheel drive vehicle according to claim 5, wherein the brake device is a wet multi-plate brake device. 6. The power transmission mechanism for a four-wheel drive vehicle according to claim 5, wherein the casing of the wet multi-plate brake device is formed integrally with the casing of the rear wheel final reduction gear.

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