JP4477459B2 - Four-wheel drive vehicle - Google Patents

Description

  The present invention relates to a four-wheel drive vehicle, and more particularly, to a four-wheel drive vehicle suitable for traveling on rough terrain at low speed, such as an agricultural work vehicle or a transport vehicle.

  As a four-wheel drive vehicle for rough terrain, a vehicle that absorbs up and down vibrations due to unevenness of a running surface by supporting a rear axle by a swing arm method is widely used. In such a swing arm type four-wheel drive vehicle, the engine and the transmission are conventionally mounted on the vehicle body frame, and the transmission on the vehicle body frame, the front wheel speed reduction part between the front wheels, and the rear wheel on the swing arm. The speed reduction unit is connected to the front wheel driving propeller shaft and the rear wheel driving propeller shaft so that power can be transmitted.

In addition, although the applicant investigated patent documents etc. about the four-wheel drive vehicle for rough terrain, the prior art document in which the four-wheel drive vehicle related to this invention was not discovered. However, there is a known related publication regarding a rear wheel drive type four-wheel vehicle (Patent Document 1, etc.).
Japanese Patent No. 2694202.

  In a four-wheel drive vehicle that supports the rear axle by a swing arm system, when the engine and transmission are mounted on the body frame, the power unit consisting of the engine and transmission is placed in the front half of the vehicle, for example, below the seat In other words, the vibration of the engine is easily transmitted to the driver, and the space around the driver is also reduced, so that the ride comfort is reduced.

  Further, since the rear wheel drive propeller shaft that connects the transmission on the vehicle body frame and the rear wheel speed reduction unit on the swing arm is mounted so as to swing up and down together with the swing of the swing arm, the front wheel drive propeller is mounted. The power transmission loss is larger than that of the shaft, and when a heavy object is loaded on the rear part such as a transport vehicle, the load of the rear wheel is increased, so that economic efficiency such as fuel consumption is lowered.

(Object of invention)
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a four-wheel drive vehicle and reduce the width of the transmission in the vehicle width direction to achieve a reduction in the size and weight of the transmission and a reduction in the width of the vehicle. is there.

In order to achieve the above object, a four-wheel drive vehicle according to claim 1 of the present application is supported by a vehicle body frame so as to be swingable up and down, and an engine and a transmission are arranged in the above order on a swing arm provided with a rear axle. Mounted side by side, the output portion of the transmission is connected to the rear axle so that power can be transmitted, and the front wheel drive propeller is connected to the front wheel drive power take-out shaft in the front wheel drive power take-out portion provided in the transmission. A front wheel drive propeller shaft that extends forward through the lower side of the engine and is connected to a front wheel speed reduction portion disposed between the front wheels so as to be capable of transmitting power; and A belt converter that connects the transmission to the transmission so as to be able to transmit power is disposed on one side in the vehicle width direction of the engine and the transmission, and the front The front-wheel driving PTO unit, is characterized in that disposed on the opposite side of the belt converter side.

According to a second aspect of the invention, according to claim 1 four-wheel drive vehicle, wherein the front-wheel drive propeller shaft is characterized in that disposed between the engine and the swing arm when viewed from the side.

According to a third aspect of the present invention, in the four-wheel drive traveling vehicle according to the first or second aspect, the front wheel drive power take-off shaft and the front wheel drive propeller shaft are V-shaped upward as viewed from the side. It is characterized by being connected to open.

According to a fourth aspect of the present invention, in the four-wheel drive traveling vehicle according to any one of the first to third aspects, the front wheel driving propeller shaft includes a front propeller shaft member, a rear propeller shaft member, and front and rear An intermediate propeller shaft member that foldably connects the two propeller shaft members, and the front end portion of the rear propeller shaft member substantially overlaps the swing fulcrum of the swing arm when viewed from the side. It is characterized in that it is connected to the intermediate propeller shaft member so as to be movable in the front-rear direction.

(1) An engine and a transmission are mounted together with a rear axle on a swing arm supported to be swingable up and down by the body frame, and a propeller shaft for driving the front wheel is provided between the transmission and the front wheel speed reduction portion. Since it is connected so that power can be transmitted, the empty space in the rear half of the vehicle, such as the lower space of the loading platform, can be used effectively for the engine and transmission arrangement, so that the vehicle can be made compact and the area around the seat In addition, it is possible to maintain a comfortable riding state for the driver by securing a wide area around the operation device.

(2) Since the engine, transmission, and rear axle are mounted on the same swing arm, even if the swing arm swings, the relative positional relationship between the transmission and the rear axle does not change, and power is transmitted to the rear axle. Loss can be reduced and economic efficiency such as fuel efficiency can be improved. It is particularly suitable for a vehicle such as a transport vehicle in which a large load is applied to the rear wheel.

(3) A front wheel drive power take-out portion is provided in a transmission disposed on the rear side of the engine, and a front wheel drive propeller shaft extending from the front wheel drive power take-out shaft in the front wheel drive power take-out portion to the front wheel speed reduction portion, Since it is arranged so as to pass under the engine, the dimension in the vehicle width direction of the transmission can be made smaller than the dimension in the vehicle width direction of the engine, and a small and lightweight vehicle transmission can be provided.

(4) Since the belt converter is arranged on one side in the vehicle width direction of the transmission and the propeller shaft for driving the front wheels is arranged on the side opposite to the belt converter side, both sides of the transmission in the vehicle width direction are respectively connected to the belt. It can be effectively used for the arrangement of the converter and the front wheel drive power take-off shaft, and the compactness in the vehicle width direction around the transmission can also be maintained.

(5) Since the front-wheel drive propeller shaft is disposed between the engine and the swing arm when viewed from the side, it is possible to avoid the front-wheel drive propeller shaft from coming into direct contact with the rough ground or an obstacle during traveling. it can.

(6) The front wheel drive power take-off shaft and the front wheel drive propeller shaft are connected so as to open upward in a V-shape when viewed from the side, so that the front wheel drive can be performed without increasing the mounting position of the engine. The propeller shaft for the engine can be arranged compactly on the lower side of the engine.

(7) The front-wheel drive propeller shaft includes a front-side propeller shaft member, a rear-side propeller shaft member, and an intermediate propeller shaft member that foldably connects both propeller-shaft members, and the rear-side propeller shaft member is Since the front end swing fulcrum is overlapped with the swing fulcrum of the swing arm when viewed from the side, it is connected to the intermediate propeller shaft member so as to be movable in the front-rear direction. The rear propeller shaft member swings around the swing fulcrum, absorbs the load applied to the front wheel drive propeller shaft during swinging, and can maintain smooth rotation of the front wheel drive propeller shaft.

  FIGS. 1-7 is embodiment of the four-wheel drive vehicle for rough terrain to which this invention is applied, and is mainly utilized for the agricultural transport vehicle etc. FIG.

[Body structure of a four-wheel drive vehicle]
FIG. 1 shows a left side surface (left side surface as viewed from the driver) of a four-wheel drive vehicle. A vehicle body frame 1 includes a pair of left and right square pipes 2 extending in the front-rear direction as a main frame portion. The square pipe 2 is integrally joined to the left and right by a plurality of cross pipes 5 arranged at intervals in the front-rear direction, and the central part in the front-rear direction is bent upward and the rear half is higher than the front half. It has become. A front frame portion 8 is integrally formed at the front end portion of the square pipe 2, and a steering handle 10, a shift shift lever 11, a two-wheel drive / four-wheel drive switching lever 12, and the like are disposed at the upper end portion of the front frame portion 8. In addition, a front cover 13 is attached. A seat support frame portion 14 is integrally formed at the center portion of the square pipe 2 in the front-rear direction, and a seat 15 is attached to the upper surface of the seat support frame portion 14.

  A front wheel speed reduction part (reduction gear case) 20 is provided at the lower end of the front frame part 8, and the front wheel speed reduction part 20 has a built-in differential gear mechanism and a front axle 21 protruding left and right. Each front axle 21 is elastically supported from above by a front wheel shock absorber 23 and is connected to the front wheel 22 via a steering mechanism such as a knuckle arm (not shown).

  A loading platform 24 and a rear fender 25 are provided on the upper side of the rear half of the square pipe 2. Further, a frame 26 that covers the driver is provided from the front end portion of the front frame portion 8 to the rear of the seat through the boarding space.

  A swing arm 30 extending rearward is supported on the cross pipe 5 disposed almost immediately below the seat 15 so as to be swingable up and down around a swing fulcrum M1, and a rear axle 31 is supported on the swing arm 30. In addition, the engine 33 and the transmission 34 are mounted so as to be lined up and down in the above order. A rear wheel speed reduction part (deceleration case part) 36 incorporating the rear axle 31 is provided at the rear lower end of the transmission 34, and the rear wheels 32 are connected to the left and right rear axles 31, respectively.

[Swing arm structure]
FIG. 2 is a plan view of the vehicle body frame 1 and the power transmission device. The swing arm 30 is made of a pipe member, and the front end portion is formed in a mountain shape. ). A support bracket 38 that protrudes forward is provided at the front end of the swing arm 30, while a support bracket 39 that protrudes rearward is provided at the center in the vehicle width direction (left-right direction) of the cross pipe 5 immediately below the seat. The support bracket 38 of the swing arm 30 is supported on the support bracket 39 of the cross pipe 5 by a spherical joint (pillow ball joint) 40. As a result, the swing arm 30 can be tilted left and right and swinged left and right within a certain range in addition to swinging up and down.

  FIG. 5 is a rear view of the swing arm 30 and the like. The rear end portion of the swing arm 30 is elastically supported from above by a pair of left and right rear shock absorbers 42 and is shaken in the left and right directions by the restriction link 43. It is regulated within a certain range. That is, a mountain-shaped pipe 44 having a top portion displaced leftward is provided at the rear end portion of the swing arm 30, and the top portion of the mountain-shaped pipe 44 and the right corner pipe 2 are connected by the restriction link 43 and pivot pins at both ends. It is pivotally connected. As a result, the swinging and tilting of the swing arm 30 is restricted within a predetermined range.

  FIG. 3 is an enlarged left side view of the swing arm 30 and the like, and the swing arm 30 is opened upward and slightly bent into a V shape (or a dogleg shape). That is, the swing arm 30 is bent so that the substantially center in the front-rear direction protrudes downward, whereby the first half of the swing arm 30 is inclined downward and the latter half is inclined downward.

[Overall configuration of power source and power transmission device]
In FIG. 3, as described above, the engine 33 and the transmission 34 are arranged on the swing arm 30 side by side in the above order, and the engine 33 is, for example, a single-cylinder general-purpose engine. A cooling fan case portion 66 is provided at the left end portion of the engine 33. The cooling fan case portion 66 is provided at the left end portion of the engine 33. A front wheel drive power take-out portion 50 is provided at the lower left end of the transmission 34, and a front wheel drive power take-out shaft 51 is provided in the front wheel drive power take-out portion 50 so as to protrude forward.

  In FIG. 2 which is a plan view, the engine 33 and the transmission 34 are arranged such that the center of the left and right widths of both 33 and 34 is displaced to the left side with respect to the vehicle width center line C1, and the right side of both 33 and 34. The surface is substantially aligned in a vertical plane parallel to the vehicle width center line C1, and a belt converter 45 is provided on the right side of both 33 and 34. In other words, the belt converter 45 is arranged on the side (left side) opposite to the arrangement side (left side) of the front wheel drive power take-out unit 50, and the belt converter 45 transmits engine power to the transmission 34. It has become.

  The lateral width (dimension in the vehicle width direction) W2 of the transmission 34 including the front wheel drive power take-out portion 50 is smaller than the lateral width W1 of the engine 33. As described above, the right side surface of the engine 33 and the transmission Since the right side surface of 34 is disposed in substantially the same vertical plane, the left end surface of the front wheel drive power take-out portion 50 is located closer to the vehicle width center line C1 than the left end surface of the engine 33. The front wheel drive power take-out shaft 51 that projects forward from the front wheel drive power take-out portion 50 has a front wheel drive propeller shaft 52 (53, 54, 55) that extends in the front-rear direction. Is connected to the input shaft 57 so that power can be transmitted.

[Detailed structure of propeller shaft for front wheel drive]
In FIG. 2, the front-wheel drive propeller shaft 52 includes three propeller shaft members 53, 54, and 55 on the front side, the middle side, and the rear side. The rear propeller shaft member 55 is connected to the front wheel drive power take-off shaft 51 via a universal joint 58 at the rear end, and extends slightly forward to the right in the lower space of the fan case portion 66 of the engine 33. The portion is connected to the rear end portion of the intermediate propeller shaft member 54 via a universal joint 62. The intermediate propeller shaft member 54 is rotatably supported in a bearing housing 60 provided in the cross pipe 5 immediately below the seat, and the front end portion is connected to the rear end portion of the front propeller shaft member 53 via the universal joint 61. It is connected. The front propeller shaft member 53 extends obliquely forward so as to approach the vehicle width center line C <b> 1, and the front end portion is connected to the input shaft 57 of the front wheel speed reduction unit 20 via the universal joint 56. The bearing housing 60 of the intermediate propeller shaft member 54 is provided at a position displaced to the left of the vehicle width center line C1.

  Returning to FIG. 3, the front wheel drive power take-out shaft 51 is disposed in a front-lowering posture substantially parallel to the rear half of the swing arm 30, and projects into the lower space of the fan case portion 66. The propeller shaft member 55 is disposed in a rearwardly lowered posture substantially parallel to the front half of the swing arm 30 and passes through the lower space of the cooling fan case 66 as described above. That is, the power take-out shaft 51 for driving the front wheels and the rear propeller shaft member 55 are arranged in a state of opening upward in a V shape with the universal joint 58 as a bottom point, and the fan of the engine 33 is placed in the V shape space. The lower end portion of the case portion 66 is arranged. The rear propeller shaft member 55 and the front wheel drive power take-out shaft 51 are both positioned between the swing arm 30 and the lower end of the engine 33 as viewed from the side. Further, the front end swing fulcrum (center of the universal joint 62) M2 of the rear propeller shaft member 55 is located at substantially the same height as the swing fulcrum M1 of the swing arm 30 and at substantially the same longitudinal position. ing.

[Construction of belt converter]
FIG. 4 is an enlarged plan view of the swing arm 30, the engine 33, the transmission 34, and the belt converter 45. The engine 33 is indicated by a virtual line. In FIG. 4, a belt converter 45 attached to the right side surface of the engine 33 and the transmission 34 is, for example, a V-belt continuously variable transmission, and a drive pulley attached to an output shaft (drive shaft) 33a of the engine 33. 68, a driven pulley 69 attached to the first shaft 81 on the input side of the transmission 34, and a V belt 70 wound around both pulleys 68, 69. Automatic shifting is performed according to the increase or decrease of the load.

[Transmission structure]
FIG. 6 shows the internal structure of the transmission 34. FIG. 6 is a developed sectional view taken along a plane passing through the shafts O1, O2, O3, O4 of the shafts 81, 82, 83 for shifting and the rear axle 31. It is. In FIG. 6, a transmission case 35 constituting the outline of the transmission 34 is formed by connecting a pair of left and right transmission case members 72 a and 72 b at a central mating surface. A case portion 74 constituting the outer case of the wheel speed reducing portion 36 is integrally formed, and a right half case of the case portion 75 constituting the outer shape of the front wheel drive power take-out portion 50 is formed at the lower left end portion of the transmission case 35. A portion 75b is integrally formed, and a left half case portion 75a, which is a separate member from the transmission case 35, is coupled to the left end mating surface L1 of the right half case portion 75b. A mating surface L1 of both the half case portions 75b and 75a is a vertical surface including the axis O5 of the power take-out shaft 51 for driving the front wheels.

  The transmission 34 is configured to be switchable to, for example, two forward speeds (low and high) and reverse, and the transmission case 35 includes a first transmission shaft 81 on the input side in order from the top as a transmission shaft, The second shaft 82 and the third shaft (output unit) 83 on the output side are disposed, and the rear axle 31 is disposed on the rear side of the third shaft 83.

  A drive-side forward low gear 85, a forward high gear 86, and a reverse sprocket 87 are integrally formed on the first shaft 81 on the input side. The second shaft 82 is rotatably fitted with a driven low gear 90 and a high gear 91, which are engaged with the driving low gear 85 and the high gear 86, respectively, via a bearing. The driven reverse sprocket 92 connected to the reverse reverse sprocket 87 via a chain 93 is rotatably fitted via a bearing, and the shift sleeve 95 is spline fitted to be axially slidable. The intermediate output gear 96 is integrally formed. A gear 97 that meshes with the intermediate output gear 96 is fixed to the third shaft 83, and an output gear 98 is integrally formed. The left end portion of the third shaft 83 projects into the front wheel drive power take-out portion 50, and a first bevel gear (primary bevel gear) 99 for driving the front wheels is fixed thereto.

  The rear wheel speed reduction unit 36 includes an input gear 100 that meshes with the output gear 98 of the third shaft 83 and a differential gear mechanism 102 that transmits power from the input gear 100 to the rear axle 31.

  The front wheel drive power take-out shaft 51 is disposed so as to extend in the front-rear direction in a posture perpendicular to each of the speed change shafts 81, 82, 83 in a plan view, and is provided in the case 75 by the front and rear bearings 110, 111. A second bevel gear (secondary bevel gear) 103 that meshes with the first bevel gear 99 of the third shaft 83 is provided on the outer peripheral surface of the front wheel drive power take-off shaft 51. The two-wheel drive / four-wheel-drive switching sleeve 104 is spline-fitted so as to be axially slidable while being fitted to the shaft 51 so as to be rotatable relative to each other. Dog claws 105 and 106 that can mesh with each other are formed on end faces facing each other in the axial direction. A switching arm 107 is engaged with an annular groove 108 formed in the 2WD 4WD switching sleeve 104, and the 2WD 4WD switching sleeve 104 is slid in the axial direction by the switching arm 107, so that the 2WD 4WD is to be switched.

  That is, in the case of four-wheel drive, the dog claws 105 and 106 are engaged with each other by moving the two-wheel drive and four-wheel drive switching sleeve 104 rearward, whereby both bevel gears 99 and 103 and two A state is assumed in which power is transmitted to the front wheel drive power take-out shaft 51 via the drive / wheel drive switching sleeve 104. On the other hand, in the case of two-wheel drive (rear wheel drive), the dog claws 105 and 106 are disengaged from each other by moving the two-wheel drive / four-wheel drive switching sleeve 104 forward, whereby the front wheel is moved from the third shaft 83. The power transmission to the drive power take-out shaft 51 is cut off. The switching arm 107 is linked to a two-wheel drive / four-wheel drive switching lever 109 shown in FIG. 4, and the two-wheel drive / four-wheel drive switching lever 109 is operated by a two-wheel drive / four-wheel drive switching operation shown in FIG. Linked to the lever 12.

[Detailed structure of intermediate propeller shaft member]
FIG. 7 is an enlarged horizontal cross-sectional view of the intermediate propeller shaft member 54 and the bearing housing 60. The bearing housing 60 is inserted into the mounting hole 113 formed in the cross pipe 5, and the bolt 114 inserted into the flange portion 60a. It is fixed to the cross pipe 5 by the above. A pair of bearings 115 and 116 are fitted on the inner peripheral surface of the bearing housing 60 at intervals in the front-rear direction, and the intermediate propeller shaft member 54 is rotatably supported by the bearings 115 and 116. The intermediate propeller shaft member 54 has spline teeth 117 formed on the outer peripheral surface of the portion protruding rearward from the rear bearing 116, and the cylindrical shaft 118 having the inner peripheral spline teeth 118 a is axially disposed on the spline teeth 117. (Fore-and-aft direction) It is spline-fitted so as to be slidable and to be rotatable integrally with the intermediate propeller shaft member 54. A yoke portion 62a of the universal joint 62 is integrally formed at the rear end portion of the cylindrical shaft 118, whereby the universal joint 62 is movable in the front-rear direction. That is, the rear propeller shaft member 55 is linked to the intermediate propeller shaft member 54 via the universal joint 62 and the cylindrical shaft 118 so that the swing fulcrum M2 at the front end can move in the front-rear direction. A spring seat (plug) 120 is fitted to the rear end portion of the cylindrical shaft 118, and a coil spring 121 is contracted between the spring seat 120 and the rear end portion of the intermediate propeller shaft member 54. Thus, the cylindrical shaft 118 is always urged backward.

  The rear portion of the intermediate propeller shaft member 54 is sealed by a double seal mechanism including a rotation seal 125 disposed on the rear side of the rear bearing 116 and a sliding seal 126 disposed on the rear side thereof. Is sealed by a single rotating seal 127 disposed on the front side of the front bearing 115. Grease is filled between the front and rear bearings 115 and 116.

  The double seal mechanism will be described in detail. Between the inner peripheral surface of the rear bearing 116 and the outer peripheral surface of the intermediate propeller shaft member 54, a cylindrical seal holding cylinder 130 that rotates integrally with the intermediate propeller shaft member 54 is press-fitted. The holding cylinder 130 extends rearward and gradually increases in diameter in two stages, and the stepped portion 130c between the first-stage expanded portion 130a and the second-stage expanded portion 130b has a radially outward portion. A flange portion 130d that protrudes in the direction is formed integrally. The rotation seal 125 is inserted between the outer peripheral surface of the first-stage enlarged diameter portion 130 a and the inner peripheral surface of the bearing housing 60, and the front end edge of the rotation seal 125 is the inner peripheral surface of the bearing housing 60. It is latched in the axial direction by a step portion 122 formed on the surface. The sliding seal 126 is inserted between the inner peripheral surface of the second-stage enlarged diameter portion 130b and the outer peripheral surface of the cylindrical shaft 118, which is larger in diameter than the first-stage enlarged diameter portion 130a. 126 is locked in the axial direction by the stepped portion 130 c and a circlip 123 fitted to the seal holding cylinder 130. A plurality of communication holes 131 are formed in the first-stage enlarged diameter portion 130a so as to allow air to pass through the inside and outside in the radial direction of the enlarged diameter portion 130a.

  A main seal lip portion 133 is formed on the inner peripheral surface of the rotation seal 125 so as to be in pressure contact with the first enlarged diameter portion 130a. The main seal lip portion 133 protrudes rearward and inwardly into the first enlarged diameter portion 130a. In addition to the lip portions 133 and 134, a pressure-contacting dust strip portion 134 is formed, and in addition to the lip portions 133 and 134, the rear end surface of the rotation seal 125 protrudes in a U-shape outwardly and presses against the front end surface of the collar portion 130d. A side dust strip portion 135 is formed. A pair of seal lip portions 126 a are formed on the inner peripheral surface of the sliding seal 126 so as to extend in the shape of a letter C in front and back and press-contact with the outer peripheral surface of the cylindrical shaft 118.

  The front rotation seal 127 is inserted between the inner peripheral surface of the bearing housing 60 and the outer peripheral surface of the intermediate propeller shaft member 54 and is axially moved by a circlip 124 fitted to the inner peripheral surface of the bearing housing 60. It is locked to. The basic structure of the front rotation seal 127 is the same as that of the rear rotation seal 125, and the inner peripheral surface has a seal lip portion 140 that is in pressure contact with the outer peripheral surface of the intermediate propeller shaft member 54 and a bifurcated double seal. A strip portion 141 is formed, and a side dust strip portion 142 is formed on the front end surface so as to protrude forward and outward in a U-shape. An annular slinger 143 made of a sheet metal is pressed against the side dust strip 142 from the front, and the slinger 143 is formed in an L-shaped cross section, and the nut 61b of the yoke 61a of the universal joint 61 is formed. It is press-fitted and fixed to the outer periphery. The nut portion 61 b is screwed to the front end male screw portion 54 b of the intermediate propeller shaft member 54. Further, the front end edge of the slinger 143 has a shape that slightly expands in a trumpet shape so that it can be easily press-fitted into the nut portion 61b.

[Two-wheel-drive]
In the case of the two-wheel drive traveling, the two-wheel drive / four-wheel drive switching sleeve 104 is moved to the front two-wheel drive position (the position of FIG. 6) by the switching arm 107 of FIG. The power to the front wheel drive power take-off shaft 51 is cut off.

  In the two-wheel drive state, in FIG. 2, the power of the engine 33 is transmitted to the transmission 34 via the belt converter 45, and in FIG. 6, from the first shaft 81 on the input side in the transmission 34, on the driving side and the driven side. The gears 96 and 97 are transmitted from the second shaft 82 to the intermediate second shaft 82 through the low gears 85 and 90 (or high gears 86 and 91) or the sprockets 87 and 92 for reverse travel at a desired speed ratio. To the third shaft 83 on the output side. Power is transmitted from the third shaft 83 on the output side to the left and right rear axles 31 via the output gear 98, the input gear 100 of the rear wheel reduction unit 36, and the differential gear mechanism 102.

[4WD]
In the case of four-wheel drive, the two-wheel drive / four-wheel drive switching sleeve 104 is moved to the rear four-wheel drive position by the two-wheel drive / four-wheel drive switching arm 107 in FIG. 6, thereby the third shaft 83 on the output side of the transmission 34 and the front wheels. The drive power take-out shaft 51 is switched to the connected state.

  In the four-wheel drive state, power is transmitted to the rear axle 31 through the same power transmission path as in the two-wheel drive state, and in addition, the bevel gears 99 and 103, the dog claws 16 and 105, and the two Power is also transmitted to the front wheel drive power take-out shaft 51 via the four-wheel drive switching sleeve 104, and the rear propeller shaft member 55, the intermediate propeller shaft member 54 and the front propeller shown in FIG. Power is transmitted to the front wheel speed reduction unit 20 via the shaft member 53 to drive the front axle 21.

[Effect of the embodiment]
(1) In FIG. 1, during traveling, the engine 33, the transmission 34, the rear axle 31 and the rear wheel 32 swing up and down together with the swing arm 30 about the swing fulcrum M1, and the rear propeller shaft accordingly. The member 55 also swings up and down, but the fulcrum M2 of the front end universal joint 62, which is the swing fulcrum of the rear propeller shaft member 64, is movable in the front-rear direction, and the swing fulcrum of the swing arm 36 Since the height substantially coincides with the height of M1, and the positions in the front-rear direction are also substantially aligned, no excessive force is applied to the rear propeller shaft member 55 during swinging, thereby improving the power transmission efficiency to the front wheels 22. It is possible to prevent the deterioration and maintain the buffer performance.

(2) In the above embodiment, as shown in FIG. 4, the front wheel drive power take-out unit 50 is provided in the transmission 34 arranged on the rear side of the engine 33, and the front wheel drive power take-out unit 50 takes out the power for driving the front wheels. Since the rear propeller shaft member 55 connected to the shaft 51 and extending forward is disposed so as to pass under the engine 33, the left and right width W2 of the transmission 34 is easily made smaller than the left and right width W1 of the engine 33. A small and lightweight transmission 34 can be provided. In addition, since the front wheel drive power take-out portion 50 is arranged on the left side of the transmission 34 and the belt converter 45 is arranged on the opposite side (right side), the left and right side space portions of the transmission 34 are respectively connected to the front wheel drive power take-out portion 50. The belt converter 45 can be effectively used for the arrangement of the belt converter 45, and the compactness of the lateral width around the transmission can be maintained.

(3) As shown in FIG. 1, an engine 33 and a transmission 34 are mounted on a swing arm 30 together with a rear axle 31, and a front-wheel drive propeller is disposed between the transmission 34 and the front-wheel reduction unit 20 at the front of the vehicle. Since the shaft 52 is connected so as to be able to transmit power, an empty space in the rear half of the vehicle, for example, the lower space of the loading platform 24 can be effectively used for the arrangement of the engine 33 and the transmission 34, thereby reducing the size of the vehicle. In addition, it is possible to maintain a comfortable riding state for the driver by securing a wide area around the seat and around the operation device.

(4) Since the engine 33, the transmission 34, and the rear axle 31 are mounted on the same swing arm 30, even if the swing arm 30 swings, the relative positional relationship between the transmission 34 and the rear axle 31 does not change. Thus, it is possible to reduce power transmission loss to the rear axle 31 and improve economic efficiency such as fuel consumption. It is particularly suitable for a vehicle such as a transport vehicle in which a large load is applied to the rear wheel.

(5) Since the rear propeller shaft member 55 of the front wheel drive propeller shaft 52 is disposed between the engine 33 and the swing arm 30 as viewed from the side as shown in FIG. It is possible to avoid the lower rear propeller shaft member 55 from coming into direct contact with uneven ground or an obstacle.

(6) As shown in FIG. 3, the front wheel drive power take-out shaft 51 and the rear propeller shaft member 55 are connected so as to open upward in a V shape, so that the mounting position of the engine 33 is not increased. The rear propeller shaft member 55 can be disposed compactly below the engine 33.

(7) As shown in FIG. 1, the front propeller shaft 52 is connected to the front propeller shaft member 53, the rear propeller shaft member 55, and the front and rear propeller shaft members 53, 55 so as to be bent. 3, the rear propeller shaft member 55 is connected by a universal joint 62 at a position where the front end swing fulcrum M2 substantially overlaps with the swing fulcrum M1 of the swing arm 30 as viewed from the side as shown in FIG. Since it is connected to the intermediate propeller shaft member 54 so as to be movable in the front-rear direction, the rear side around the swing fulcrum M2 at the same position as the swing fulcrum M1 of the swing arm 30 when viewed from the side as the swing arm 30 swings. The propeller member 55 swings, and the load applied to the rear propeller shaft member 55 during the swinging is absorbed, so that smooth rotation of the entire front wheel driving propeller shaft 52 can be maintained.

(8) As shown in FIG. 7, in the intermediate propeller shaft member 54, which is disposed at a position where water or mud is likely to be applied, and in which the cylindrical shaft 118 is slidably fitted, it is sealed with the bearing housing 60. Since the sliding seal 126 dedicated to sliding in the axial direction and the rotational seal 125 dedicated to rotation are provided as a structure, the seal life can be extended, and the rotational seal 125 and the sliding seal 126 can be combined. Since the position is shifted in the axial direction, the radial dimension of the bearing housing 60 can be kept compact.
[Other Embodiments of the Invention]

(1) The four-wheel-drive traveling vehicle to which the present invention can be applied is not limited to a farm vehicle, but can be used for various swing-type four-wheel-drive traveling vehicles such as agricultural or civil engineering work vehicles. Applicable.

(2) In the above-described embodiment, the belt converter 45 is disposed on the right side of the transmission 34 and the front wheel drive power take-out unit 50 is disposed on the left side.

(3) The arrangement structure of the shafts and gears in the transmission shown in FIG. 6 is merely an example, and in the transmissions other than the structure as shown in FIG. If it is provided, the invention of the present application can be applied.

It is a left view of a four-wheel drive traveling vehicle (embodiment) to which the present invention is applied. It is a top view of the vehicle body frame and power transmission device of the four-wheel drive traveling vehicle of FIG. FIG. 2 is an enlarged left side view of the swing arm, engine, and transmission of FIG. 1. FIG. 4 is a plan view of FIG. 3 with the engine removed. It is a rear view of the swing arm part of FIG. FIG. 4 is a developed sectional view of the transmission cut along a plane that passes through each shaft for speed change. It is a horizontal cross-sectional enlarged view of an intermediate | middle propeller shaft member and a bearing housing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Body frame 20 Front wheel reduction part 21 Front axle 22 Front wheel 30 Swing arm 31 Rear axle 32 Rear wheel 33 Engine 34 Transmission 35 Transmission case 36 Rear wheel reduction part 45 Belt converter 50 Front wheel drive power takeout part 51 Front wheel drive power 51 Extraction shaft 52 Propeller shaft for front wheel drive 53 Front propeller shaft member 54 Intermediate propeller shaft member 55 Rear propeller shaft member 58, 61, 62 Universal joint 66 Fan case for cooling

Claims (4)

On the swing arm supported by the body frame so as to be able to swing up and down and having a rear axle, the engine and the transmission are mounted side by side in the above order,
The output portion of the transmission is coupled to the rear axle so as to be able to transmit power, and can transmit power to the front wheel drive propeller shaft via the front wheel drive power take-off shaft in the front wheel drive power take-out portion provided in the transmission. Concatenate,
The front wheel drive propeller shaft extends forward through the lower side of the engine, and is coupled to a front wheel speed reduction unit disposed between the front wheels so as to transmit power.
A belt converter that connects the engine and the transmission so as to be able to transmit power is disposed on one side in the vehicle width direction of the engine and the transmission,
A four-wheel drive traveling vehicle characterized in that the front wheel drive power take-out section is disposed on the side opposite to the belt converter side . The four-wheel drive traveling vehicle according to claim 1, wherein the front-wheel drive propeller shaft is disposed between the engine and the swing arm as viewed from the side. The four-wheel drive traveling according to claim 1 or 2, wherein the front wheel drive power take-off shaft and the front wheel drive propeller shaft are coupled so as to open upward in a V shape when viewed from the side. car. The front wheel drive propeller shaft includes a front propeller shaft member, a rear propeller shaft member, and an intermediate propeller shaft member that foldably connects the front and rear propeller shaft members,
The front end of the rear propeller shaft member claims, characterized in that at a position substantially overlapping with the swing fulcrum of the swing arm when viewed from the side, and ligated in the longitudinal direction movable in the intermediate propeller shaft member by a universal joint The four-wheel drive vehicle as described in any one of 1-3 .

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