1. A work machine comprising: a first vehicle body including: a prime mover, and a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover; and a second vehicle body including: wheels provided at both ends in the vehicle width direction, a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven, an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels, an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle, wherein the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted, and the second vehicle body includes an axle extension case disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.

2. The work machine according to claim 1, wherein the axle power transmission mechanism includes: a wheel axle that rotates integrally with the wheels coaxially, a gear that transmits an axle output of the second axle to the wheel axle, and a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear, and the axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.

3. The work machine according to claim 2, wherein the second axle includes: a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion, and the axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.

4. The work machine according to any one of claims 1 to 3, wherein the first vehicle body includes: a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover, and the vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.

5. An axle extension case applied to a work machine including: a first vehicle body including: a prime mover, and a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover, and a second vehicle body including: wheels provided at both ends in the vehicle width direction, a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven, an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels, an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle, the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted, and the axle extension case is included in the second vehicle body, disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.

6. The axle extension case according to claim 5, wherein the axle power transmission mechanism includes: a wheel axle that rotates integrally with the wheels coaxially, a gear that transmits an axle output of the second axle to the wheel axle, and a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear, and the axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.

7. The axle extension case according to claim 6, wherein the second axle includes: a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion, and the axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.

8. The axle extension case according to any one of claims 5 to 7, wherein the first vehicle body includes: a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover, and the vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.

Description:WORK MACHINE AND AXLE EXTENSION CASE OF WORK MACHINE

TECHNICAL FIELD
[0001]
The present invention relates to a work machine and an axle extension case configured to surround an axle included in the work machine.

BACKGROUND ART
[0002]
In the related art, as a work machine including a first vehicle body and a second vehicle body, for example, a work machine disclosed in WO 2014/059379 A (FIG. 1 and the like) is known. The work machine includes a tractor as a first vehicle body and a harvester as a second vehicle body. A tractor with wheels detached is mounted on an upper portion of the harvester. On the other hand, the harvester itself is provided with wheels. The axle output of the rear wheel axle of the tractor is transmitted toward the rear wheel of the harvester via a power transmission mechanism. When the wheels of the harvester are rotationally driven based on the axle output of the tractor, the tractor and the harvester integrally travel in a state where the tractor is mounted on the upper portion.

SUMMARY OF THE INVENTION
TECHNICAL PROBLEM
[0004]
In a state where the first vehicle body is mounted on the second vehicle body as in this type of work machine, the vehicle weight and the vehicle height increase by the amount of the first vehicle body as compared with a case where the second vehicle body is a single body. In order to perform stable traveling and work, it is effective to dispose the wheels of the second vehicle body at the further outer side in the vehicle width direction as compared with the case where the second vehicle body is a single body. In a case where the wheel is disposed at the further outer side, it is required to appropriately protect each component that transmits power to the wheel.
[0005]
Therefore, in view of the above, an object of the present invention is to provide a work machine including a first vehicle body and a second vehicle body and capable of appropriately protecting each component that transmits power to a wheel of the second vehicle body, and an axle extension case of the work machine.

SOLUTION TO PROBLEM
[0006]
A technical solution of the present invention for solving the above technical problem is characterized as follows. A work machine according to the present invention includes: a first vehicle body including: a prime mover, and a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover; and a second vehicle body including: wheels provided at both ends in the vehicle width direction, a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven, an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels, an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle, wherein the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted. The second vehicle body includes an axle extension case disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.
[0007]
In the work machine according to the present invention, the axle power transmission mechanism includes: a wheel axle that rotates integrally with the wheels coaxially, a gear that transmits an axle output of the second axle to the wheel axle, and a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear. The axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.
[0008]
In the work machine according to the present invention, the second axle includes: a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion. The axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.
[0009]
In the work machine according to the present invention, the first vehicle body includes: a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover. The vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.
[0010]
An axle extension case according to the present invention includes: a first vehicle body including: a prime mover, and a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover, and a second vehicle body including: wheels provided at both ends in the vehicle width direction, a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven, an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels, an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle, the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted. The axle extension case is included in the second vehicle body, disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.
[0011]
In the axle extension case according to the present invention, the axle power transmission mechanism includes: a wheel axle that rotates integrally with the wheels coaxially, a gear that transmits an axle output of the second axle to the wheel axle, and a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear. The axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.
[0012]
In the axle extension case according to the present invention, the second axle includes: a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion. The axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.
[0013]
In the axle extension case according to the present invention, the first vehicle body includes: a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover. The vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.

ADVANTAGEOUS EFFECTS OF THE INVENTION
[0014]
According to the present invention, even when the wheel is disposed at the further outer side, the second axle can be protected without being exposed to the outside. In addition, it is possible to suppress application of an excessive load to each component that transmits power to the wheel. As described above, each component that transmits power to the wheel can be appropriately protected.

BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
FIG. 1 is a side view of a work machine according to an embodiment of the present invention;
FIG. 2 is a plan view of the work machine illustrated in FIG. 1;
FIG. 3 is a diagram illustrating a power transmission system of the work machine illustrated in FIG. 1;
FIG. 4 is a perspective view of a rear wheel, an axle power transmission mechanism, and an axle case and an axle extension case surrounding a second rear axle included in the work machine illustrated in FIG. 1;
FIG. 5 is a perspective cross-sectional view of the rear wheel, the axle power transmission mechanism, and the axle case and the axle extension case surrounding the second rear axle included in the work machine illustrated in FIG. 1 taken along a second rear axle;
FIG. 6 is a cross-sectional view of the rear wheel, the axle power transmission mechanism, and the axle case and the axle extension case surrounding the second rear axle included in the work machine illustrated in FIG. 1, and is a partially enlarged view of one of the left and right sides in the vehicle width direction; and
FIG. 7 is a cross-sectional view of a rear wheel, an axle power transmission mechanism, and an extension hub in a comparative example, and is a partially enlarged view of one of the left and right sides in a vehicle width direction.

DESCRIPTION OF THE EMBODIMENTS
[0016]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view illustrating an entire work machine 100 according to an embodiment of the present invention. FIG. 2 is a plan view of the work machine 100. Left/right, upper/lower, front/rear of arrows appropriately shown in the respective drawings correspond to left/right directions, upper/lower directions, and front/rear directions, respectively. In the present embodiment, the vehicle width direction of the work machine 100 corresponds to the left direction and the right direction, and the vehicle length direction of the work machine 100 corresponds to the front direction and the rear direction.
[0017]

As illustrated in FIGS. 1 and 2, the work machine 100 includes a first vehicle body 10 and a second vehicle body 20. In the present embodiment, the first vehicle body 10 is a vehicle body in which all the wheels are separated from the traveling vehicle body of the tractor. The second vehicle body 20 is a combine harvester. The first vehicle body 10 is mounted above the second vehicle body 20 so that the driver can visually recognize the front direction when the driver sits on a driver seat 15 of the first vehicle body 10. That is, the work machine 100 is a so-called tractor-on-top type combine harvester. The first vehicle body 10 and the second vehicle body 20 are not limited to the tractor and the combine harvester as long as the positional relationship at the time of mounting is similar to that described above.
[0018]
The tractor that is the first vehicle body 10 includes a prime mover 11, a first front axle 12, a first rear axle 13, and a transmission 14. The prime mover 11 is a diesel engine, an electric motor, or the like. The first front axle 12 is provided at the front of the first vehicle body 10 in the vehicle length direction. The first front axle 12 is disposed so as to extend in the left and right vehicle width directions, and is configured to be rotationally driven based on power of the prime mover 11. The first rear axle 13 is provided behind the first front axle 12 of the first vehicle body 10 in the vehicle length direction. The first rear axle 13 is disposed so as to extend in the left and right vehicle width directions, and is configured to be rotationally driven based on power of the prime mover 11. In the present embodiment, the traveling device such as wheels is not provided on the first front axle 12 and the first rear axle 13.
[0019]
The transmission 14 transmits the power of the prime mover 11 to the first front axle 12 and the first rear axle 13 while changing the speed. The transmission 14 can switch a gear position of transmission power and can switch forward rotation and reverse rotation of the first front axle 12 and the first rear axle 13 by a shift operation of a driver. In the vehicle length direction of the first vehicle body 10, the driver seat 15 is provided between the first front axle 12 and the first rear axle 13. A steering wheel 16 is provided at the front of the driver seat 15. The driver's steering using the steering wheel 16 is transmitted toward a rear wheel 22 of the second vehicle body 20 described later.
[0020]
The combine harvester, which is the second vehicle body 20, includes a work device such as a reel 20a and a cutting blade 20b at a front end portion, and is configured to be able to execute agricultural works such as harvest, threshing, and accommodation while traveling in a field. The second vehicle body 20 includes a front wheel 21, a rear wheel 22, a second front axle 23, a second rear axle 24, an axle case 25, an axle power transmission mechanism 26, a vehicle body power transmission mechanism 27, and an axle extension case 30.
[0021]
The front wheels 21 and the rear wheels 22 are each provided at both left and right ends in the vehicle width direction, respectively. The front wheel 21 is located at the front of the second vehicle body 20 and at the rear of the work device. The rear wheel 22 is positioned behind the front wheel 21 in the vehicle length direction of the second vehicle body 20. The second front axle 23 is disposed so as to extend in the vehicle width direction toward the left and right front wheels 21, and is configured to be rotationally driven. The second rear axle 24 is disposed so as to extend in the vehicle width direction toward the left and right rear wheels 22, and is configured to be rotationally driven. In the present embodiment, a total of four wheels including the front wheels 21 and the rear wheels 22 are provided as the traveling device.
[0022]
The axle case 25 is located at the rear bottom of the second vehicle body 20 so as to correspond to the second rear axle 24. The axle case 25 is disposed so as to extend in the vehicle width direction toward the left and right rear wheels 22. The axle case 25 is configured to partially surround the second rear axle 24, and accommodates the second rear axle 24 so as to be relatively rotatable (see FIGS. 4, 5, and 6). The axle extension cases 30 are disposed one by one left outside and right outside of the axle case 25 in the vehicle width direction and inside of the left and right axle power transmission mechanisms 26 in the vehicle width direction. The axle extension case 30 is configured to partially surround the second rear axle 24, and accommodates the second rear axle 24 in a relatively rotatable manner (see FIGS. 4, 5, and 6). That is, the axle extension case 30 is disposed so as to extend the axle case 25 left outside and right outside of the axle case 25 in the vehicle width direction. Therefore, the second rear axle 24 is surrounded by the axle extension cases 30 left outside and right outside of the axle case 25 in the vehicle width direction in addition to the axle case 25.
[0023]
One axle power transmission mechanism 26 is disposed inside of the rear wheel 22 and outside of the second rear axle 24 so as to correspond to each of the left and right rear wheels 22. The axle power transmission mechanism 26 incorporates a gear, a bearing, and the like, and is configured to receive the axle output of the second rear axle 24 that is rotationally driven to transmit power toward the rear wheels 22 (see FIGS. 4, 5, and 6). The axle case 25, the axle extension case 30, and the axle power transmission mechanism 26 will be described in detail later.
[0024]
The vehicle body power transmission mechanism 27 is configured to receive the axle output of the rotationally driven first front axle 12 to transmit power toward the second front axle 23 and the second rear axle 24. That is, the vehicle body power transmission mechanism 27 transmits the power generated by the first vehicle body 10 to the drive system of the second vehicle body 20. In the present embodiment, the vehicle body power transmission mechanism 27 is located at the left of the second vehicle body 20, and the axle output is input from the first front axle 12 at the left of the first vehicle body 10. The vehicle body power transmission mechanism 27 may be configured by, for example, incorporating a gear, a drive axle, a drive chain, and the like in a case. In this case, the vehicle body power transmission mechanism 27 may be formed in an elongated shape, and may transmit power from one end to the other end while bending between the one end and the other end.
[0025]
More specifically, one end 27a of the vehicle body power transmission mechanism 27 is disposed at a position corresponding to the first front axle 12 and is mechanically connected to the left first front axle 12. The vehicle body power transmission mechanism 27 extends substantially horizontally rearward from the one end 27a, and is bent downward at a substantially center portion of the first vehicle body 10 in the vehicle length direction. When reaching the bottom portion of the second vehicle body 20, the vehicle body power transmission mechanism 27 directed downward is bent toward the right in the vehicle width direction, and the other end 27b of the vehicle body power transmission mechanism 27 reaches substantially the center portion in the vehicle width direction. The other end 27b of the vehicle body power transmission mechanism 27 is mechanically connected to a four-wheel drive assembly 28 of the second vehicle body 20.
[0026]
As a result, the axle output of the first front axle 12 on the left side can be input to the one end 27a of the vehicle body power transmission mechanism 27, transmitted to the other end 27b, and then input to the four-wheel drive assembly 28 of the second vehicle body 20. The four-wheel drive assembly 28 of the second vehicle body 20 transmits the input power so as to rotationally drive the second front axle 23 and the second rear axle 24. The second vehicle body 20 travels integrally with the first vehicle body 10 by rotationally driving the front wheel 21 and the rear wheel 22 based on the power transmitted via the vehicle body power transmission mechanism 27 in a state where the first vehicle body 10 is mounted.
[0027]
As illustrated in FIG. 3, the transmission 14 of the first vehicle body 10 includes a propulsion axle 14a, a main transmission unit 14b, an auxiliary transmission unit 14c, a shuttle unit 14d, and a front transmission unit 14e. The propulsion axle 14a is rotatably supported by a housing case (transmission case) of the transmission 14, and power from a crankshaft of the prime mover 11 is transmitted to the propulsion axle 14a. The main transmission unit 14b includes a plurality of gears and a shifter that changes connection of the gears. The main transmission unit 14b changes and outputs (shifts) the rotation input from the propulsion axle 14a by appropriately changing connection (meshing) of the plurality of gears with the shifter.
[0028]
Similar to the main transmission unit 14b, the auxiliary transmission unit 14c includes a plurality of gears and a shifter that changes connection of the gears. The auxiliary transmission unit 14c changes and outputs (shifts) the rotation input from the main transmission unit 14b by appropriately changing connection (meshing) of the plurality of gears with a shifter. The shuttle unit 14d includes a shuttle axle 14d1 and a forward/backward switching unit 14d2. The power output from the auxiliary transmission unit 14c is transmitted to the shuttle axle 14d1 via a gear or the like. The forward/backward switching unit 14d2 is configured by, for example, a hydraulic clutch, and switches a rotation direction of the shuttle axle 14d1, that is, a rotation direction of the first front axle 12 and the first rear axle 13 by turning on/off the hydraulic clutch. The shuttle axle 14d1 is connected to a rear differential device 13a. The rear differential device 13a rotatably supports the first rear axle 13.
[0029]
The front transmission unit 14e includes a first clutch 14e1 and a second clutch 14e2. The first clutch 14e1 and the second clutch 14e2 can transmit power from the propulsion axle 14a, and for example, the power of the shuttle axle 14d1 is transmitted via a gear and a transmission axle. The power from the first clutch 14e1 and the second clutch 14e2 can be transmitted to the first front axle 12 via a front transmission axle 14e3. Specifically, the front transmission axle 14e3 is connected to a front differential 12a, and the front differential 12a rotatably supports the first front axle 12.
[0030]
The first clutch 14e1 and the second clutch 14e2 are configured by a hydraulic clutch or the like. An oil passage is connected to the first clutch 14e1, and the oil passage is connected to a first operation valve (not illustrated) to which the hydraulic oil discharged from the hydraulic pump is supplied. The first clutch 14e1 is switched between the connected state and the disconnected state depending on the opening degree of the first operation valve. An oil passage is connected to the second clutch 14e2, and a second operation valve (not illustrated) is connected to the oil passage. The second clutch 14e2 is switched between the connected state and the disconnected state depending on the opening degree of the second operation valve. The first operation valve and the second operation valve are, for example, solenoid valve equipped two-position switching valves, and are switched to a connected state or a disconnected state by exciting or demagnetizing a solenoid of the solenoid valve.
[0031]
When the first clutch 14e1 is in the disconnected state and the second clutch 14e2 is in the connected state, power of the shuttle axle 14d1 is transmitted to the first front axle 12 through the second clutch 14e2. As a result, the first front axle 12 and the first rear axle 13 are brought into a four-wheel drive state (4WD) in which they are rotationally driven by power, and the rotational speeds of the first front axle 12 and the first rear axle 13 are substantially the same (4WD constant speed state). On the other hand, when the first clutch 14e1 is in the connected state and the second clutch 14e2 is in the disconnected state, the four-wheel drive state is established, and the rotational speed of the first front axle 12 is faster than the rotational speed of the first rear axle 13 (4WD acceleration state). When the first clutch 14e1 and the second clutch 14e2 are in the disconnection state, the power of the shuttle axle 14d1 is not transmitted to the first front axle 12, and a two-wheel drive state (2WD) is established.
[0032]
When the work machine 100 is caused to travel, the transmission 14 of the first vehicle body 10 is operated to be in a four-wheel drive state in order to transmit power from the first vehicle body 10 to the second vehicle body 20. The vehicle body power transmission mechanism 27 outputs the rotational power input from the first front axle 12 to the four-wheel drive assembly 28 of the second vehicle body 20. Power is transmitted to a front propulsion axle 28a and a rear propulsion axle 28b of the second vehicle body 20 via a gear or the like of the four-wheel drive assembly 28.
[0033]
The front propulsion axle 28a transmits power from the four-wheel drive assembly 28 to the second front axle 23 rotatably supported by a differential 23a. The transmitted power rotationally drives the front wheels 21 provided at the left and right ends of the second front axle 23. The rear propulsion axle 28b transmits power from the four-wheel drive assembly 28 to the second rear axle 24 rotatably supported by a differential device 24a. The transmitted power rotationally drives the rear wheels 22 at the left and right ends via the axle power transmission mechanism 26 left outside and right outside of the second rear axle 24.
[0034]

As illustrated in FIGS. 4 and 5, the axle case 25 and the axle extension case 30 of the second vehicle body 20 are tubular housings. In the axle extension case 30, one end portion 31 and the other end portion 32 are defined in the left and right vehicle width directions, and the one end portion 31 and the other end portion 32 are opening ends. The axle case 25 is connected to the one end portion 31 of the axle extension case 30 at an opening end portion 25a at each outer end thereof in the left-right direction. The one end portion 31 is attachable to and detachable from the axle case 25 by bolt fastening or the like. The axle case 25 is provided with a tie rod guard 25b covering a tie rod disposed substantially parallel to the axle case 25.
[0035]
The axle power transmission mechanism 26 of the second vehicle body 20 includes a gear case 26a incorporating a plurality of gears and a wheel axle 26b. The gear case 26a is connected to the other end portion 32 of the axle extension case 30 at its inner end portion in the left-right direction. The other end portion 32 is attachable to and detachable from the gear case 26a by bolt fastening or the like. The rear wheel 22 is directly and coaxially fixed to (a flange portion 26b1 of) the wheel axle 26b each of left outside of the axle power transmission mechanism 26 and right outside of the axle power transmission mechanism 26.
[0036]
As illustrated in FIGS. 5 and 6, the second rear axle 24 includes a second axle base portion 24b and a second axle extension portion 24c. The second axle base portion 24b is a yoke axle and is surrounded by the axle case 25. The differential device 24a is included in substantially the center portion of the axle case 25 in the left and right vehicle width direction, and is mechanically connected to the rear end of the rear propulsion axle 28b. The rear propulsion axle 28b is pivotally supported so as to penetrate the axle case 25 from the outer face of the axle case 25 toward the differential device 24a inside. The second axle base portion 24b is mechanically connected to the differential device 24a, and extends outward in the left and right vehicle width directions from the differential device 24a as a starting point. As a result, the second axle base portion 24b rotates based on the power transmitted via the vehicle body power transmission mechanism 27.
[0037]
In the second axle base portion 24b, an outer end portion 24b1 in each of the left and right vehicle width direction are exposed from outer ends of the axle case 25. The outer end portion 24b1 enters an internal space of the axle extension case 30 from the one end portion 31. The second axle extension portion 24c is an exterior yoke and is connected to the second axle base portion 24b. More specifically, an inner end portion 24c1 of the second axle extension portion 24c is integrally connected to the outer end portion 24b1 of the second axle base portion 24b by a coupling 24d. The coupling 24d allows the second axle extension portion 24c to integrally rotate coaxially with the second axle base portion 24b.
[0038]
The axle extension case 30 in the mounted state surrounds the exposed portion of the second axle base portion 24b, the coupling 24d, and the second axle extension portion 24c of the second rear axle 24. That is, the connection portion of the second axle base portion 24b and the second axle extension portion 24c is located in the internal space of the axle extension case 30 and surrounded by the axle extension case 30. In the second axle extension portion 24c, an outer end portion 24c2 in each of the left and right vehicle width direction is exposed from the other end portion 32 of the axle extension case 30. The outer end portion 24c2 is configured by a bevel gear, and enters an internal space of the gear case 26a. The second axle extension portion 24c is rotatably and axially supported inside the gear case 26a via a bearing. Accordingly, the second axle extension portion 24c integrally rotates coaxially with the second axle base portion 24b to input power to the gear of the axle power transmission mechanism 26.
[0039]
FIG. 6 is a cross-sectional view of the second rear axle 24, the axle power transmission mechanism 26, the axle case 25, and the axle extension case 30, and illustrates one of portions in the left-right direction. The configuration of the other of portions in the left-right direction is also similar to that illustrated in FIG. 6. As illustrated in FIG. 6, the axle power transmission mechanism 26 includes a bearing 26c, a ring gear 26d, and a gear shaft 26e in addition to the gear case 26a and the wheel axle 26b described above. The wheel axle 26b is an axle, and includes a circular flange portion 26b1 and an axle portion 26b2. The flange portion 26b1 is coaxially fixed to the axle portion 26b2 and is disposed outside the gear case 26a in the vehicle width direction. The circular end face of the flange portion 26b1 faces the inside of the rear wheel 22. The wheel portion of the rear wheel 22 can be directly attached to and detached from the circular end face of the flange portion 26b1 by bolt fastening or the like. Here, “can be directly attached to and detached from” means that the rear wheel 22 can be directly attached to and detached from in a state where an intervening member such as an extension hub does not exist between the wheel portion of the rear wheel 22 and the circular end face of the flange portion 26b1.
[0040]
The axle portion 26b2 extends inward in the vehicle width direction from the flange portion 26b1 and is incorporated in the gear case 26a. The axle portion 26b2 is rotatably and axially supported inside the gear case 26a via the bearing 26c which is a bearing. The axle portion 26b2 is disposed so as to have a different axle from and be parallel to the second rear axle 24. Two bearings 26c may be provided so as to be away from each other in the axial direction of the axle portion 26b2. Thus, the wheel axle 26b integrally rotates coaxially with the rear wheel 22.
[0041]
The ring gear 26d has an outer diameter larger than the diameter of the axle portion 26b2, and is incorporated in the gear case 26a. Gear teeth are formed on the outer periphery of the ring gear 26d. The ring gear 26d is fixed between the two bearings 26c coaxially with the axle portion 26b2, and is disposed such that gear teeth face inward. Accordingly, the ring gear 26d integrally rotates coaxially with the wheel axle 26b.
[0042]
The gear shaft 26e is configured such that both ends are bevel gears, and is incorporated in the gear case 26a. The gear shaft 26e is rotatably and axially supported inside the gear case 26a via a bearing which is a bearing. The gear shaft 26e is interposed between the ring gear 26d and the outer end portion 24c2 of the second axle extension portion 24c. The gear shaft 26e is disposed such that the axis of the gear shaft 26e is inclined with respect to each of the second rear axle 24 and the axle portion 26b2. The bevel gear of the gear shaft 26e at one end meshes with the ring gear 26d. The bevel gear of the gear shaft 26e at the other end meshes with the bevel gear at the outer end portion 24c2 of the second axle extension portion 24c. Accordingly, the gear shaft 26e receives power from the second axle extension portion 24c to output the received power to the ring gear 26d.
[0043]
With the above configuration, when the prime mover 11 of the first vehicle body 10 is driven, the power of the prime mover 11 is output from the first front axle 12 and the first rear axle 13 via the transmission 14 in the four-wheel drive state. In the present embodiment, the axle output of the left first front axle 12 is input to the four-wheel drive assembly 28 of the second vehicle body 20 via the vehicle body power transmission mechanism 27 (see FIG. 3). The input power integrally rotates the second axle base portion 24b and the second axle extension portion 24c via the rear propulsion axle 28b and the differential device 24a. As a result, the rotational power is input from the second axle extension portion 24c to the axle power transmission mechanism 26.
[0044]
In the axle power transmission mechanism 26, the gear shaft 26e and the ring gear 26d rotate in accordance with rotation of the bevel gear at the outer end portion 24c2 of the second axle extension portion 24c. The wheel axle 26b pivotally supported by the bearing 26c also rotates integrally with the rotating ring gear 26d, and the rear wheel 22 rotates. As described above, the power of the prime mover 11 of the first vehicle body 10 is transmitted to the rear wheels 22 of the second vehicle body 20 through various transmission mechanisms, and the rear wheels 22 are rotationally driven, whereby the traveling of the work machine 100 is achieved.
[0045]

As described above, the work machine 100 according to the embodiment of the present invention includes the first vehicle body 10 and the second vehicle body 20. The first vehicle body 10 includes the prime mover 11 and the first front axle 12. The first front axle 12 is disposed so as to extend in the vehicle width direction, and is configured to be rotationally driven based on the power of the prime mover 11. The second vehicle body 20 includes the rear wheel 22, the second rear axle 24, the axle power transmission mechanism 26, the vehicle body power transmission mechanism 27, and the axle case 25. The rear wheels 22 are provided at both ends in the vehicle width direction. The second rear axle 24 is disposed so as to extend in the vehicle width direction toward the rear wheels 22, and is configured to be rotationally driven. The axle power transmission mechanism 26 is interposed between the rear wheel 22 and the second rear axle 24, and is configured to receive an axle output of the second rear axle 24 that is rotationally driven to transmit power toward the rear wheel 22. The vehicle body power transmission mechanism 27 is configured to receive the axle output of the rotationally driven first front axle 12 to transmit power toward the second rear axle 24. The axle case 25 is disposed so as to extend in the vehicle width direction toward the rear wheels 22 and is configured to surround the second rear axle 24. The second vehicle body 20 travels integrally with the first vehicle body 10 by rotationally driving the rear wheel 22 based on the power transmitted via the vehicle body power transmission mechanism 27 in a state where the first vehicle body 10 is mounted.
[0046]
The second vehicle body 20 further includes the axle extension case 30. The axle extension case 30 is disposed outside of the axle case 25 in the vehicle width direction and inside of the axle power transmission mechanism 26 in the vehicle width direction, and is configured to surround the second rear axle 24.
[0047]
In a state where the first vehicle body 10 is mounted on the second vehicle body 20, the vehicle weight and the vehicle height are increased by the first vehicle body 10 as compared with a case where the second vehicle body 20 is a single body. In order to perform stable traveling and work, it is effective to dispose the wheels of the second vehicle body 20 at the further outer side in the vehicle width direction as compared with the case where the second vehicle body 20 is a single body. In a case where the wheel is disposed at the further outer side, it is required to appropriately protect each component that transmits power to the wheel.
[0048]
According to the above configuration, when the second rear axle 24 is extended in the vehicle width direction and the rear wheel 22 is disposed at the further outer side together with the axle power transmission mechanism 26, the second rear axle 24 can be surrounded by the axle extension case 30. Therefore, even when the rear wheel 22 is disposed at the further outer side, the second rear axle 24 can be protected without being exposed to the outside. When the rear wheel 22 is disposed at the further outer side, for example, it is conceivable to interpose an extension hub or the like between the rear wheel 22 and the axle power transmission mechanism 26. When an extension hub or the like is interposed, an excessive load is applied to the axle power transmission mechanism 26 or the like when the rear wheel 22 is rotationally driven, and it is difficult to protect each component from the load. On the other hand, according to the above configuration, the rear wheel 22 can be disposed at the further outer side together with the axle power transmission mechanism 26 without interposing the extension hub or the like between the rear wheel 22 and the axle power transmission mechanism 26. Therefore, it is possible to suppress application of an excessive load to each component. As described above, each component that transmits power to the wheel can be appropriately protected.
[0049]
In the present embodiment, the axle power transmission mechanism 26 includes the wheel axle 26b, the gear (ring gear 26d, gear shaft 26e), and the gear case 26a. The wheel axle 26b rotates integrally with the rear wheel 22 coaxially. The gear transmits the axle output of the second rear axle 24 to the wheel axle 26b. The gear case 26a pivotally supports the wheel axle 26b inside via the bearing 26c, and incorporates the gear. The axle extension case 30 is configured such that one end portion 31 in the vehicle width direction is connected to the axle case 25, and the other end portion 32 in the vehicle width direction is connected to the gear case 26a.
[0050]
As in the comparative example illustrated in FIG. 7, for example, when the rear wheel 22 is disposed at the further outer side in the vehicle width direction with an extension hub EH interposed between the rear wheel 22 and the wheel axle 26b, a load is likely to be applied to each component of the axle power transmission mechanism 26 according to the rotational drive. In this case, in particular, an excessive load is applied to the wheel axle 26b, the durability of the bearing 26c supporting the wheel axle 26b decreases, and the replacement frequency tends to increase.
[0051]
On the other hand, according to the above configuration, the rear wheel 22 can be disposed at the further outer side together with the axle power transmission mechanism 26 without interposing the extension hub EH or the like between the rear wheel 22 and the wheel axle 26b. Therefore, in particular, the load on the wheel axle 26b can be suppressed, and the durability of the bearing 26c supporting the wheel axle 26b can be improved, so that the replacement frequency can be reduced. In addition, the wheel axle 26b can be disposed to have a different axle from the second rear axle 24, and the position of the wheel can be easily adjusted. The reduction ratio can be easily adjusted according to the number of teeth of the gear incorporated in the gear case 26a. Further, by configuring the one end portion 31 and/or the other end portion 32 of the axle extension case 30 to be detachable by, for example, bolt fastening or the like, attachment and detachment can be easily performed.
[0052]
In the present embodiment, the second rear axle 24 includes the second axle base portion 24b and the second axle extension portion 24c. The second axle base portion 24b is disposed such that the outer end portion 24b1 in the vehicle width direction is exposed from the axle case 25, and the second axle base portion 24b rotates based on the power transmitted via the vehicle body power transmission mechanism 27. The second axle extension portion 24c is connected to the outer end portion 24b1 of the second axle base portion 24b, and integrally rotates coaxially with the second axle base portion 24b to input power to the gear of the axle power transmission mechanism 26. The axle extension case 30 is configured to surround the connection portion of the second axle base portion 24b and the second axle extension portion 24c.
[0053]
According to the above configuration, the wheel position can be disposed at a desired position by adjusting the length of the second axle extension portion 24c and connecting the second axle extension portion 24c to the second axle base portion 24b. In a state where the outer end portion 24b1 of the second axle base portion 24b is exposed from the axle case 25, the second axle extension portion 24c can be connected before the axle extension case 30 is attached. Therefore, the second axle extension portion 24c can be easily connected to the second axle base portion 24b.
[0054]
In the present embodiment, the first vehicle body 10 includes the first front axle 12 and the first rear axle 13. The first front axle 12 is provided at the front in the vehicle length direction, and is configured to be rotationally driven based on the power of the prime mover 11. The first rear axle 13 is provided behind the first front axle 12 in the vehicle length direction, and is configured to be rotationally driven simultaneously with the first front axle 12 based on the power of the prime mover 11. The vehicle body power transmission mechanism 27 is configured to receive an axle output of at least one of the first front axle 12 that is rotationally driven and the first rear axle 13 that is rotationally driven to transmit power toward the second axle.
[0055]
According to the above configuration, one selected from among the first front axle 12 and the first rear axle 13 can be connected to the vehicle body power transmission mechanism 27. That is, a portion, of the vehicle body power transmission mechanism 27, to which the axle output is input can be selected. Therefore, design variations such as the arrangement position, handling, and mechanism design of the vehicle body power transmission mechanism 27 can be expanded with respect to various aspects of the first vehicle body 10 and the second vehicle body 20, and it is possible to reliably transmit power between the vehicle bodies.
[0056]

In the above embodiment, the vehicle body power transmission mechanism 27 receives the axle output of the first front axle 12 to transmit power toward both the second front axle 23 and the second rear axle 24. Alternatively, for example, the vehicle body power transmission mechanism 27 may receive the axle output of the first rear axle 13 to transmit power toward both the second front axle 23 and the second rear axle 24. In addition, the vehicle body power transmission mechanism 27 may receive the axle output of any one of the first front axle 12 and the first rear axle 13 to transmit power toward any one of the second front axle 23 and the second rear axle 24. When the vehicle body power transmission mechanism 27 receives the axle output of the first front axle 12 to transmit power toward the second rear axle 24, the axle output of the first rear axle 13 transmits power toward the second front axle 23 by, for example, a chain.
[0057]
In the above embodiment, the vehicle body power transmission mechanism 27 is configured to receive the axle output of the first front axle 12 that is rotationally driven to transmit power toward the second front axle 23 and the second rear axle 24. Alternatively, the vehicle body power transmission mechanism 27 may be configured to receive the axle output of the front transmission axle 14e3 to transmit power toward the second rear axle 24. In this case, the axle output of the front transmission axle 14e3 is input to the vehicle body power transmission mechanism 27 at the front of the first vehicle body, and the power is transmitted to the left side of the first vehicle body using a chain or the like. The axle output of the first rear axle 13 may be transmitted to the second front axle 23, or the power of the vehicle body power transmission mechanism 27 may be transmitted.
[0058]
In the above embodiment, the axle case 25 and the axle extension case 30 are provided in the second vehicle body 20 so as to surround the second rear axle 24. Alternatively, for example, the front wheel 21 of the second vehicle body 20 may be steerable, and the axle case 25 and the axle extension case 30 may be configured to surround the second front axle 23.
[0059]
It should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is indicated not by the above description but by the claims, and it is intended that meanings equivalent to the claims and all modifications within the scope are included.

REFERENCE SIGNS LIST
[0060]
10 first vehicle body
11 prime mover
12 first front axle
13 first rear axle
14 transmission
20 second vehicle body
21 front wheel
22 rear wheel
23 second front axle
24 second rear axle
24b second axle base portion
24b1 outer end portion
24c second axle extension portion
24d coupling
25 axle case
26 axle power transmission mechanism
26a gear case
26b wheel axle
26b1 flange portion
26b2 axle portion
26c bearing
26d ring gear
26e gear shaft
27 vehicle body power transmission mechanism
30 axle extension case
31 one end portion
32 the other end portion
, Claims:WE CLAIM:

1. A work machine comprising:
a first vehicle body including:
a prime mover, and
a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover; and
a second vehicle body including:
wheels provided at both ends in the vehicle width direction,
a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven,
an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels,
an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and
a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle, wherein
the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted, and
the second vehicle body includes an axle extension case disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.

2. The work machine according to claim 1, wherein
the axle power transmission mechanism includes:
a wheel axle that rotates integrally with the wheels coaxially,
a gear that transmits an axle output of the second axle to the wheel axle, and
a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear, and
the axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.

3. The work machine according to claim 2, wherein
the second axle includes:
a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and
a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion, and
the axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.

4. The work machine according to any one of claims 1 to 3, wherein
the first vehicle body includes:
a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and
a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover, and
the vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.

5. An axle extension case applied to a work machine including:
a first vehicle body including:
a prime mover, and
a first axle disposed to extend in a vehicle width direction and configured to be rotationally driven based on power of the prime mover, and
a second vehicle body including:
wheels provided at both ends in the vehicle width direction,
a second axle disposed to extend in the vehicle width direction toward the wheels and configured to be rotationally driven,
an axle power transmission mechanism interposed between the each wheel and the second axle and configured to receive an axle output of the second axle that is rotationally driven to transmit power toward the wheels,
an axle case disposed to extend in the vehicle width direction toward the wheels and configured to surround the second axle, and
a vehicle body power transmission mechanism configured to receive an axle output of the first axle that is rotationally driven to transmit power toward the second axle,
the second vehicle body travels integrally with the first vehicle body by rotationally driving the wheels based on power transmitted via the vehicle body power transmission mechanism in a state where the first vehicle body is mounted, and
the axle extension case is included in the second vehicle body, disposed outside of the axle case in the vehicle width direction and inside of the axle power transmission mechanism in the vehicle width direction and configured to surround the second axle.

6. The axle extension case according to claim 5, wherein
the axle power transmission mechanism includes:
a wheel axle that rotates integrally with the wheels coaxially,
a gear that transmits an axle output of the second axle to the wheel axle, and
a gear case that pivotally supports the wheel axle via a bearing inside and incorporates the gear, and
the axle extension case has one end portion in the vehicle width direction connected to the axle case, and the other end portion in the vehicle width direction connected to the gear case.

7. The axle extension case according to claim 6, wherein
the second axle includes:
a second axle base portion disposed such that an outer end portion in the vehicle width direction is exposed from the axle case, the second axle base portion rotating based on power transmitted via the vehicle body power transmission mechanism, and
a second axle extension portion connected to the outer end portion of the second axle base portion and configured to input power to the gear of the axle power transmission mechanism by integrally rotating coaxially with the second axle base portion, and
the axle extension case is configured to surround a connection portion of the second axle base portion and the second axle extension portion.

8. The axle extension case according to any one of claims 5 to 7, wherein
the first vehicle body includes:
a first front axle provided as the first axle at a front in a vehicle length direction and configured to be rotationally driven based on power of the prime mover, and
a first rear axle provided as the first axle behind the first front axle in the vehicle length direction and configured to be rotationally driven simultaneously with the first front axle based on power of the prime mover, and
the vehicle body power transmission mechanism is configured to receive an axle output of at least one of the first front axle that is rotationally driven and the first rear axle that is rotationally driven to transmit power toward the second axle.