Front axle case and work vehicle

Abstract

To reduce manufacturing costs of a front axle case by allowing the front axle case mounted with a power steering cylinder to be used commonly among work vehicles having different structures.SOLUTION: A front axle case includes: a body case storing a drive shaft for transmitting power input from an input shaft to a front wheel; a power steering cylinder for steering the front wheel; and a cylinder support case that supports the power steering cylinder. The cylinder support case includes an insertion part which is fixed to the body case and to which the input shaft can be inserted. The power steering cylinder is located on a fixation side of the cylinder support case with respect to the body case. The body case includes a storage part capable of storing a distal end portion of the input shaft. The storage part is located on an opposite side to the fixation side of the cylinder support case with respect to the drive shaft in the body case.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a front axle case mounted on a work vehicle such as a tractor, and a work vehicle including the front axle case.

Background Art

[0002] As a front axle case mounted on a work vehicle or the like, the following configuration is known. An input case is attached to the center in the left-right direction of a main body case that houses a drive shaft extending in the left-right direction. An input shaft for transmitting power to the drive shaft is inserted into the input case from the rear side of the vehicle. A double-rod type power steering cylinder is supported by the input case. In the power steering cylinder, when both rods move left and right in conjunction with each other, the left and right front wheels that are rotationally driven by the drive shaft are steered. Patent Document 1 discloses an example of the above configuration.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the destination where the work vehicle is provided is a narrow land, work vehicles operating on such land are required to have workability (ease of work), and tend to select a small and small turning structure. For example, a work vehicle with a short wheelbase (the distance between the axles of the front and rear wheels) is desired. In terms of shortening the wheelbase, it is advantageous for the power steering cylinder, which is an important part for steering, to be located on the front side of the vehicle with respect to the main body case. In this case, for protection when the vehicle contacts or collides with an obstacle in front, it is desirable to arrange the power steering cylinder in a position surrounded by a guard component.

[0005] On the other hand, when the destination is a vast area of ​​land, a sense of stability is required for the work vehicle that works on such land. For this reason, there is a tendency for a large work vehicle with a long wheelbase to be desired. In a work vehicle with a long wheelbase, there is sufficient space to arrange the power steering cylinder on the rear side of the vehicle relative to the main body case, making it easy to arrange such a power steering cylinder. Furthermore, in the above arrangement, even if the vehicle comes into contact with or collides with an obstacle in front of the vehicle, the main body case acts as a guard to protect the power steering cylinder.

[0006] Thus, the desired structure of the work vehicle (particularly the wheelbase) differs depending on the destination, and the desired position of the power steering cylinder on the front axle case also differs. Conventionally, front axle cases with different positions of the power steering cylinder relative to the main body case (front and rear) were manufactured and prepared for each different destination. For this reason, it was necessary to procure different dedicated parts for each destination to manufacture the front axle case, which increased the manufacturing cost of the front axle case.

[0007] The present invention has been made to solve the above-mentioned problems, and its object is to provide a front axle case on which a power steering cylinder is mounted that can be shared (commonly used) between work vehicles with different structures (e.g. wheelbases), thereby reducing manufacturing costs, and a work vehicle equipped with such a front axle case. [Means for solving the problem]

[0008] The front axle case according to one aspect of the present invention is a front axle case including a main body case that houses a drive shaft for transmitting power input from an input shaft to a front wheel, and further includes a power steering cylinder for steering the front wheel and a cylinder support case for supporting the power steering cylinder. The cylinder support case is fixed to the main body case and has an insertion portion through which the input shaft can be inserted. The power steering cylinder is located on the fixed side of the cylinder support case with respect to the main body case. The main body case has a housing portion capable of housing the tip of the input shaft, and the housing portion is located on the side opposite to the fixed side of the cylinder support case with respect to the drive shaft in the main body case.

[0009] The work vehicle according to another aspect of the present invention includes the above-described front axle case and an input shaft that is housed in the insertion portion or the housing portion of the front axle case and transmits power to the drive shaft inside the main body case.

Effects of the Invention

[0010] According to the above configuration, it is possible to share the front axle case on which the power steering cylinder is mounted among work vehicles having different structures. Thereby, the manufacturing cost of the front axle case can be reduced.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying out the Invention

[0012] Regarding the embodiments of the present invention, if described based on the drawings, it is as follows. In this embodiment, a tractor is taken as an example of the work vehicle for description, but as the work vehicle, in addition to the tractor, a rice transplanter, a combine harvester, a civil engineering and construction work device, etc. can also be considered.

[0013] Also, in this specification, the directions are defined as follows. First, the direction in which the tractor as the work vehicle advances during work is defined as "front", and the opposite direction is defined as "rear". Also, the right side facing the advancing direction of the tractor is defined as right, and the left side is defined as left. And the direction perpendicular to the front-rear direction and the left-right direction of the tractor is defined as the up-down direction. At this time, the downstream side in the direction of gravity is defined as down, and the opposite side (upstream side) is defined as up. In the drawings, the front direction is appropriately indicated by F, the rear direction by B, the left direction by L, the right direction by R, the up direction by U, and the down direction by D.

[0014] 〔1. Schematic Configuration of Tractor〕 FIG. 1 is a side view showing the schematic configuration of a tractor 1 which is an example of the work vehicle of this embodiment. In FIG. 1, for the purpose of clarifying the internal configuration of the tractor 1, the bonnet 4, the front wheels 6 and the rear wheels 7 are shown by a dashed line, and the rest are shown by a solid line.

[0015] The tractor 1 is provided with a vehicle body frame 2. In front of the vehicle body frame 2, a mounting portion 2a for a balance weight is provided. When a working machine is attached to the rear of the tractor 1, a balance weight is attached to the mounting portion 2a as necessary. Thereby, the front-rear weight balance of the tractor 1 is kept good.

[0016] The vehicle body frame 2 supports the engine 3. The engine 3 is constituted by, for example, a diesel engine, but is not limited thereto, and may be constituted by, for example, a gasoline engine. The engine 3 is covered by a bonnet 4.

[0017] On the vehicle body frame 2, the left and right front wheels 6 are supported so as to be drivable and steerable via a front axle case 5. Details of the front axle case 5 will be described later.

[0018] A transmission device T is attached to the rear of the vehicle body frame 2. On the rear side portion of the transmission device T, the left and right rear wheels 7 are attached so as to be drivable via a rear axle case. The transmission device T is constituted by having a plurality of rotating shafts, gears, etc., and transmits the rotational power of the engine 3 to the rear wheels 7. Further, when the drive mode of the tractor 1 is set to the 4WD (Four-Wheel Drive) mode, the rotational power of the engine 3 is also transmitted to a drive shaft 21 (see FIG. 6) in the front axle case 5 via the transmission device T and an input shaft 5a, and is transmitted from the drive shaft 21 to the front wheels 6. Thereby, the front wheels 6 are driven together with the rear wheels 7.

[0019] An hydraulic lift unit 8 is provided above the rear part of the transmission device T. The hydraulic lift unit 8 has a hydraulic device such as a lifting cylinder. A working machine is attached to the rear of the hydraulic lift unit 8 via a three-point link mechanism. By raising and lowering the three-point link mechanism by the hydraulic lift unit 8, the working machine can be raised and lowered.

[0020] Above the hydraulic lift unit 8, a driver's seat 9 is arranged via a seat mount (not shown). A steering wheel 10 is provided in front of the driver's seat 9. Also, an operation lever LV and pedals P are provided around the driver's seat 9. The operator (driver) can drive (operate) the tractor 1 by sitting on the driver's seat 9 and operating the steering wheel 10, the operation lever LV, and the pedals P.

[0021] The operation lever LV includes a forward / reverse shift lever, a main transmission lever, a sub-transmission lever, a PTO (Power Take Off) shift lever, a 4WD shift lever, etc. The 4WD shift lever is a lever for switching the drive mode of the tractor 1 between a 2WD mode that drives only the rear wheels 7 and a 4WD mode that drives the front wheels 6 and the rear wheels 7. Note that a part of the operation lever LV may be replaced with a button. The pedals P include an accelerator pedal, a brake pedal, and a clutch pedal.

[0022] [2. About the front axle case] (2-1. Basic structure) FIG. 2 is a perspective view of the front axle case 5 from the rear. FIG. 3 is a rear view of the front axle case 5. FIG. 4 is a plan view of the front axle case 5. FIG. 5 is a vertical cross-sectional view of the front axle case 5. The front axle case 5 includes a main body case 11, a power steering cylinder 12, and a cylinder support case 13.

[0023] The main body case 11 is a case that is long in the left-right direction as a whole. The main body case 11 houses a drive shaft 21 (see FIG. 6) for transmitting the power input from the input shaft 5a to the front wheels 6. A pair of drive shafts 21 are provided corresponding to the left and right front wheels 6, and each extends in the left-right direction within the main body case 11.

[0024] The power steering cylinder 12 is an actuator for steering the left and right front wheels 6 and is positioned to extend in the left - right direction. In the present embodiment, the power steering cylinder 12 is composed of a double - rod hydraulic cylinder (double - acting cylinder). When hydraulic pressure is supplied to the power steering cylinder 12 in response to a steering operation, the piston within the power steering cylinder 12 moves in the left - right direction. As a result, a pair of left and right rods, that is, the first rod 12a and the second rod 12b, move simultaneously in the left or right direction. Consequently, the left and right front wheels 6 are steered in response to the steering operation and the steering is assisted. Details of the configuration for steering the left and right front wheels 6 by the power steering cylinder 12 will be described later.

[0025] The power steering cylinder 12 constitutes part of a hydraulic or electro - hydraulic power steering mechanism. Here, the hydraulic power steering mechanism assists the steering operation by driving a hydraulic pump that supplies hydraulic pressure to the power steering cylinder 12 with the engine 3. On the other hand, the electro - hydraulic power steering mechanism assists the steering operation by driving the above - mentioned hydraulic pump with a motor.

[0026] The cylinder support case 13 supports the power steering cylinder 12. The cylinder support case 13 is fixed to the main body case 11 from one side in the front - rear direction. In the examples of FIGS. 2 to 5, the cylinder support case 13 is fastened and fixed to the rear - side surface of the main body case 11 near the center in the left - right direction by bolts 14 (see FIG. 5) from the rear - side of the vehicle.

[0027] The cylinder support case 13 has an insertion portion 13a. The insertion portion 13a is located and extends in the front-rear direction, and has an insertion hole 13a1 through which the input shaft 5a can be inserted. The cylinder support case 13 supports the above-described power steering cylinder 12 that extends in the left-right direction at a position above the insertion portion 13a. As a result, the power steering cylinder 12 is located on the fixed side of the cylinder support case 13 with respect to the main body case 11. In the examples of FIGS. 2 to 5, the power steering cylinder 12 is located on the rear side of the vehicle with respect to the main body case 11 (see FIGS. 4 and 5 in particular).

[0028] (2-2. About the power transmission system) FIG. 6 is a skeleton diagram of the power transmission system in the front axle case 5. A bevel gear 5a1 is fixed to the tip of the above-described input shaft 5a (the end opposite to the transmission device T). The bevel gear 5a1 meshes with the ring gear 22 of the front-wheel final reduction mechanism 20 in the front axle case 5. The power transmitted from the transmission device T via the input shaft 5a is transmitted to the ring gear 22 via the bevel gear 5a1. The power transmitted to the ring gear 22 is transmitted to the left and right drive shafts 21 via the respective gears in the differential gear case 23 fixed to the ring gear 22. From the left and right drive shafts 21, the above-described power is transmitted to the left and right front axles 26 via the kingpin 24, the final gear 25, and the like. Thereby, on each of the left and right sides, the front wheels 6 attached to the front axle 26 are rotationally driven.

[0029] (2-3. About the steering mechanism) As shown in FIGS. 2 to 5, the front axle case 5 of the present embodiment further includes a pair of a fixed gear case 31, a rotating gear case 32, and an outer cover body 33 on the left and right. That is, the fixed gear case 31 includes a left fixed gear case 31L and a right fixed gear case 31R. The rotating gear case 32 includes a left rotating gear case 32L and a right rotating gear case 32R. The outer cover body 33 includes a left outer cover body 33L and a right outer cover body 33R.

[0030] The left fixed gear case 31L is detachably connected to one end portion 11a of the main body case 11 in the axial direction (left - right direction) in which the drive shaft 21 extends, and houses the kingpin 24 (see FIG. 6 on the left side). The left rotating gear case 32L is rotatably connected to the left fixed gear case 31L with the above - mentioned kingpin 24 as the rotation axis. The left outer cover body 33L is fixed to the left rotating gear case 32L and supports the front axle 26 to which the left front wheel 6 is attached.

[0031] The right fixed gear case 31R is detachably connected to the other end portion 11b of the main body case 11 in the axial direction (left - right direction) in which the drive shaft 21 extends, and houses the kingpin 24 (on the right side). The right rotating gear case 32R is rotatably connected to the right fixed gear case 31R with the above - mentioned kingpin 24 as the rotation axis. The right outer cover body 33R is fixed to the right rotating gear case 32R and supports the front axle 26 to which the right front wheel 6 is attached.

[0032] The front axle case 5 of the present embodiment further includes a pair of knuckle arms 34, ball joints 35, and tie rods 36. That is, the knuckle arm 34 includes a first knuckle arm 34a and a second knuckle arm 34b. The ball joint 35 includes a first ball joint 35a and a second ball joint 35b. The tie rod 36 includes a first tie rod 36a and a second tie rod 36b.

[0033] The first knuckle arm 34a is fixed to one of the rotating gear cases 32. And the first knuckle arm 34a rotates with the kingpin 24 housed in the fixed gear case 31 that is rotatably connected to the above - mentioned one rotating gear case 32 as the rotation axis. In the examples of FIGS. 2 to 5, the first knuckle arm 34a is fixed to the left rotating gear case 32L and rotates with the kingpin 24 housed in the left fixed gear case 31L as the rotation axis.

[0034] The second knuckle arm 34b is fixed to the other rotation gear case 32. And the second knuckle arm 34b rotates about the kingpin 24 accommodated in the fixed gear case 31 that is rotatably connected to the other rotation gear case 32. In the examples of FIGS. 2 to 5, the second knuckle arm 34b is fixed to the right rotation gear case 32R and rotates about the kingpin 24 accommodated in the right fixed gear case 31R.

[0035] The ball joints 35 are respectively connected to both ends of the power steering cylinder 12. More specifically, the first ball joint 35a is connected to one end of the power steering cylinder 12, that is, the tip end of the first rod 12a (the end opposite to the piston). The second ball joint 35b is connected to the other end of the power steering cylinder 12, that is, the tip end of the second rod 12b (the end opposite to the piston).

[0036] The tie rod 36 connects the knuckle arm 34 and the ball joint 35. More specifically, the first tie rod 36a connects the first knuckle arm 34a and the first ball joint 35a. The second tie rod 36b connects the second knuckle arm 34b and the second ball joint 35b.

[0037] Therefore, for example, in the states shown in FIGS. 2 and 3, when the piston in the power steering cylinder 12 moves in the left-right direction, and as a result, the first rod 12a and the second rod 12b move in the left-right direction, the first knuckle arm 34a connected to the first ball joint 35a and the first tie rod 36a via the first rod 12a rotates in one direction about the kingpin 24. At the same time, the second knuckle arm 34b connected to the second ball joint 35b and the second tie rod 36b via the second rod 12b rotates in the same direction as above. As a result, the left rotation gear case 32L to which the first knuckle arm 34a is fixed rotates in the same direction as above integrally with the left outer cover body 33L. Also, the right rotation gear case 32R to which the second knuckle arm 34b is fixed rotates in the same direction as above integrally with the right outer cover body 33R. As a result, the left front wheel 6 and the right front wheel 6 attached to the respective front axles 26 of the left outer cover body 33L and the right outer cover body 33R are steered.

[0038] (2-3. Details of the main body case) As shown in FIG. 5, the main body case 11 of the front axle case 5 has a housing portion 40. The housing portion 40 is formed in a size capable of housing the tip portion (bevel gear 5a1) of the input shaft 5a. In the state of FIG. 5, the input shaft 5a is inserted into the insertion portion 13a of the cylinder support case 13, and the tip portion of the input shaft 5a is not housed in the housing portion 40. As a result, the inside of the housing portion 40 is simply in a hollow state.

[0039] The housing portion 40 is located on the side of the main body case 11 opposite to the fixed side of the cylinder support case 13 with respect to the drive shaft 21. In the example of FIG. 5, since the cylinder support case 13 is fixed to the rear side of the vehicle of the main body case 11 and is located on the rear side of the vehicle with respect to the drive shaft 21, the housing portion 40 is located on the front side of the vehicle with respect to the drive shaft 21.

[0040] Note that when the input shaft 5a is inserted into the insertion portion 13a as shown in FIG. 5, processing according to the size and shape of the input shaft 5a, assembly of bearings, etc. are appropriately performed on the inner surface of the insertion portion 13a.

[0041] In a configuration where, as in the present embodiment, the cylinder support case 13 has the insertion portion 13a and the main body case 11 has the accommodation portion 40, as a configuration for transmitting power from the input shaft 5a to the front wheels 6 via the drive shaft 21, either of the following two configurations can be selected. The first configuration is a configuration in which the input shaft 5a is inserted into the insertion hole 13a1 of the insertion portion 13a of the cylinder support case 13 and power is transmitted to the front wheels 6, as shown in FIGS. 2 to 5. Note that the posture of the front axle case 5 at this time is defined as the first posture. On the other hand, the second configuration is a configuration in which the tip portion (bevel gear 5a1) of the input shaft 5a is accommodated in the accommodation portion 40 of the main body case 11 and power is transmitted to the front wheels 6. Note that the posture of the front axle case 5 at this time is defined as the second posture.

[0042] The second configuration can be realized by rotating the portion shown by the solid line by 180° about the axis AX passing through the center in the left-right direction in the up-down direction in the front axle case 5 shown in FIG. 7. Specifically, the portion shown by the solid line is the main body case 11, the power steering cylinder 12, the cylinder support case 13, the knuckle arm 34, the ball joint 35, and the tie rod 36.

[0043] FIG. 8 is a perspective view from the rear of the front axle case 5 in the second posture. FIG. 9 is a rear view of the front axle case 5 in the second posture. FIG. 10 is a plan view of the front axle case 5 in the second posture. FIG. 11 is a vertical sectional view of the front axle case 5 in the second posture. In FIG. 11, since the tip portion of the input shaft 5a is located in the accommodation portion of the main body case 11, the inside of the insertion portion 13a of the cylinder support case 13 is simply in a hollow state.

[0044] Note that FIG. 11 shows the front axle case 5 having the cylinder support case 13 before processing the insertion hole 13a1 (see FIG. 5) in the insertion portion 13a. If the insertion hole 13a1 has been processed in the insertion portion 13a, the above-described insertion hole 13a1 may be closed with a lid portion (plug). In this case, entry of foreign matter (sand, stones, gravel, dust, etc.) into the inside of the main body case 11 through the insertion hole 13a1 is reduced.

[0045] On the other hand, on the inner surface 40a of the housing portion 40, processing according to the size and shape of the input shaft 5a, assembly of bearings, etc. are appropriately performed. Note that the above processing also includes the formation of a hole for inserting the input shaft 5a into the housing portion 40.

[0046] As shown in FIGS. 8 to 11, in the second posture of the front axle case 5, one end portion 11a of the main body case 11 is connected to the right fixed gear case 31R, and the other end portion 11b is connected to the left fixed gear case 31L. Further, the first knuckle arm 34a is fixed to the right rotating gear case 32R, and the second knuckle arm 34b is fixed to the left rotating gear case 32L.

[0047] In the first configuration (first posture) of the front axle case 5 shown in FIGS. 2 to 5, since the input shaft 5a is inserted into the insertion portion 13a of the cylinder support case 13, the fixed side of the cylinder support case 13 with respect to the main body case 11 is on the rear side of the vehicle. Therefore, the power steering cylinder 12 supported by the cylinder support case 13 is also located on the rear side of the vehicle with respect to the main body case 11. Such an arrangement of the power steering cylinder 12 is easy to apply to a vehicle model with a long wheelbase. Further, the above arrangement is also effective from the viewpoint of protecting the power steering cylinder 12 from contact with an obstacle in front. For this reason, the first configuration is suitable for the tractor 1 whose destination is a vast land and which operates on such land.

[0048] On the other hand, in the second configuration (second posture) of the front axle case 5 shown in FIGS. 8 to 11, in the main body case 11, since the tip end portion of the input shaft 5a is accommodated in the accommodation portion 40 (see FIG. 11) located on the side opposite to the fixed side of the cylinder support case 13, the fixed side of the cylinder support case 13 with respect to the main body case 11 is on the front side of the vehicle. Therefore, the power steering cylinder 12 supported by the cylinder support case 13 is also located on the front side of the vehicle with respect to the main body case 11. In such an arrangement of the power steering cylinder 12, it becomes easy to shorten the wheelbase, and thus it is particularly effective when the destination is a narrow area where workability (ease of work) is required.

[0049] Thus, in the front axle case 5 of this embodiment, a part (main body case 11, power steering cylinder 12, cylinder support case 13, knuckle arm 34, ball joint 35, and tie rod 36) can be integrally turned forward and backward for use. Thereby, among vehicle models with different wheelbases, the above-mentioned part of the front axle case 5 can be shared (used interchangeably). In other words, it is not necessary to prepare front axle cases in which the position of the power steering cylinder is different in the front-back direction with respect to the main body case for each vehicle model with a different wheelbase. Therefore, by sharing the above-mentioned parts of the front axle case 5, the manufacturing cost of the front axle case 5 can be reduced.

[0050] In particular, in this embodiment, each rod (first rod 12a, second rod 12b) of the power steering cylinder 12 is connected to the tie rod 36 via the ball joint 35. For this reason, the angle formed by each rod of the power steering cylinder 12 and the tie rod 36 is changed (adjusted) between the first posture and the second posture of the front axle case 5, and the knuckle arm 34 can be fixed to the rotation gear case 32. Thereby, as shown in FIGS. 5 and 11, even when the contact surface (mounting surface) S between the rotation gear case 32 and the knuckle arm 34 is inclined, for example, upward in the front, according to the forward-backward interchange (reversal) of the main body case 11 and the like, the mounting position of the knuckle arm 34 with respect to the rotation gear case 32 is changed, and the knuckle arm 34 can be attached to the rotation gear case 32.

[0051] That is, from the perspective of enabling the knuckle arm 34 to be attached to the rotating gear case 32 by integrally reversing only the remaining parts (main body case 11, power steering cylinder 12, cylinder support case 13, knuckle arm 34, ball joint 35, and tie rod 36) without swapping the fixed gear case 31, rotating gear case 32, and outer cover body 33 left and right, it is desirable that the front axle case 5 has the following configuration. That is, it is desirable that the rods (first rod 12a and second rod 12b) at both ends of the power steering cylinder 12 are connected to the knuckle arm 34 via the ball joint 35 and the tie rod 36, respectively.

[0052] (2-5. Regarding the covering part) As shown in FIGS. 5 and 11 etc., the front axle case 5 further includes a covering part 15. The covering part 15 covers the insertion part 13a and the accommodating part 40 and is attached to the vehicle body frame 2 (see FIG. 1) from below. Therefore, the front axle case 5 is supported by the covering part 15.

[0053] Specifically, the covering part 15 has a front covering member 15a and a rear covering member 15b. In the first posture of the front axle case 5 shown in FIGS. 2 to 5, the front covering member 15a covers the accommodating part 40 of the front axle case 5 and supports the main body case 11, while the rear covering member 15b covers the insertion part 13a and supports the cylinder support case 13. In the second posture of the front axle case 5 shown in FIGS. 8 to 11, the front covering member 15a covers the insertion part 13a and supports the cylinder support case 13, while the rear covering member 15b covers the accommodating part 40 and supports the main body case 11.

[0054] The outer peripheral surfaces of the insertion portion 13a and the housing portion 40 described above are both formed in a cylindrical shape centered on the axis C (see FIGS. 5 and 11) extending in the front-rear direction. Therefore, when the covering portion 15 (front covering member 15a, rear covering member 15b) covers the insertion portion 13a and the housing portion 40, the front axle case 5 can rotate (roll) left and right about the axis C as the rotation center. That is, the covering portion 15 also serves as an axle case support portion 16 that supports the front axle case 5 so as to be rollable left and right with respect to the vehicle body frame 2. By supporting the front axle case 5 so as to be rollable, when the left and right front wheels 6 are supported by the front axle case 5, even if there is a difference in the ground contact pressure between the left and right front wheels 6, the left and right front wheels 6 move up and down in opposite directions due to the rotation of the front axle case 5. As a result, the ground contact pressures of the left and right front wheels 6 are maintained substantially equal.

[0055] Further, in order for the axle case support portion 16 to support the front axle case 5, a high rigidity is originally required for the portion supported by the axle case support portion 16. In the present embodiment, the insertion portion 13a and the housing portion 40 are formed in a portion where such high rigidity is originally required. That is, the portion where high rigidity is required in the support of the front axle case 5 is used as the portion (insertion portion 13a, housing portion 40) through which the input shaft 5a is inserted or housed.

[0056] Thus, from the viewpoint of effectively using the portion that requires high rigidity in the front axle case 5 as the insertion portion 13a or the housing portion 40, it is desirable that the covering portion 15 that covers the insertion portion 13a and the housing portion 40 also serves as the axle case support portion 16 as in the present embodiment.

[0057] The tractor 1 as the work vehicle of the present embodiment described above includes the above-described front axle case 5 and an input shaft 5a. The input shaft 5a is accommodated in the insertion portion 13a or the accommodation portion 40 of the front axle case 5 and transmits power to the drive shaft 21 inside the main body case 11. With this configuration, when realizing a work vehicle according to the destination (work vehicles with different wheelbases), it is not necessary to prepare different front axle cases 5 for each destination, so it is expected to realize a work vehicle according to the destination at low cost.

[0058] 〔3. Others〕 When a part of the front axle case 5 is reversed front and back, the front covering member 15a and the rear covering member 15b may also be reversed front and back together.

[0059] In the present embodiment, the power steering cylinder 12 is configured as a hydraulic cylinder, but it may be configured as an electric cylinder.

[0060] 〔4. Supplementary Note〕 The front axle case 5 and the tractor 1 (work vehicle) described in the present embodiment can be expressed as follows.

[0061] The front axle case of Supplementary Note (1) is a front axle case including a main body case that houses a drive shaft for transmitting power input from an input shaft to the front wheels, a power steering cylinder for steering the front wheels, and a cylinder support case that supports the power steering cylinder, and further includes the cylinder support case is fixed to the side surface of the main body case and has an insertion portion through which the input shaft can be inserted, the power steering cylinder is located on the fixed side of the cylinder support case with respect to the main body case, the main body case has an accommodation portion capable of accommodating the tip of the input shaft, the accommodation portion is located on the side of the main body case opposite to the fixed side of the cylinder support case with respect to the drive shaft.

[0062] The front axle case of Supplementary Note (2) is the front axle case described in Supplementary Note (1), where it is detachably connected to one end and the other end of the main body case in the axial direction in which the drive shaft extends, and a fixed gear case that houses a kingpin, a rotating gear case that is rotatably connected to each of the fixed gear cases with the kingpin as a rotation axis, an outer cover body that is fixed to each of the rotating gear cases and supports a front axle to which the front wheels are attached, a knuckle arm that is fixed to each of the rotating gear cases and rotates with the kingpin as a rotation axis, ball joints that are respectively connected to both ends of the power steering cylinder, and a tie rod that connects the knuckle arm and the ball joint.

[0063] The front axle case of Supplementary Note (3) is the front axle case described in Supplementary Note (1) or (2), where it further includes a covering portion that covers the insertion portion and the housing portion, and the covering portion also serves as an axle case support member that supports the front axle case so as to be rollable left and right with respect to the vehicle body frame.

[0064] The work vehicle of Supplementary Note (4) includes the front axle case described in any one of Supplementary Notes (1) to (3), and an input shaft that is housed in the insertion portion or the housing portion of the front axle case and transmits power to the drive shaft inside the main body case.

[0065] As described above, the embodiments of the present invention have been explained. However, the scope of the present invention is not limited thereto, and it can be implemented with expansion or modification without departing from the gist of the invention.

Industrial Applicability

[0066] The front axle case of the present invention can be used in a working vehicle such as a tractor.

Explanation of Signs

[0067] 1 Tractor (working vehicle) 2 Vehicle body frame 5 Front axle case 5a Input shaft 5a1 Bevel gear (tip portion) 6 Front wheel 11 Main body case 11a One end portion 11b The other end portion 12 Power steering cylinder 12a First rod 12b Second rod 13 Cylinder support case 13a Insertion portion 13a1 Insertion hole 15 Cover portion 15a Front cover member 15b Rear cover member 16 Axle case support portion 21 Drive shaft 24 Kingpin 26 Front axle 31 Fixed gear case 31L Left fixed gear case 31R Right fixed gear case 32 Rotating gear case 32L Left rotating gear case 32R Right rotating gear case 33 Outer cover body 33L Left outer cover body 33R Right outer cover body 34 Knuckle arm 34a First knuckle arm 34b Second knuckle arm 35 Ball joint 35a First ball joint 35b Second ball joint 36 Tie rod 36a First tie rod 36b Second tie rod 40 Receiving part

Claims

1. A front axle case comprising a main body case that houses a drive shaft for transmitting power input from an input shaft to a front wheel, a power steering cylinder for steering the front wheel, and a cylinder support case that supports the power steering cylinder. The cylinder support case is fixed to the main body case and has an insertion portion through which the input shaft can be inserted. The power steering cylinder is located on the fixed side of the cylinder support case with respect to the main body case. The main body case has a housing portion that can house the tip of the input shaft. The housing portion is located on the side of the main body case opposite to the fixed side of the cylinder support case with respect to the drive shaft. Front axle case.

2. A fixed gear case that is detachably connected to one end and the other end of the main body case in the axial direction in which the drive shaft extends and houses a kingpin, A rotating gear case that is rotatably connected to each of the fixed gear cases with the kingpin as a rotation axis, An outer cover body that is fixed to each of the rotating gear cases and supports a front axle to which the front wheel is attached, A knuckle arm that is fixed to each of the rotating gear cases and rotates with the kingpin as a rotation axis, Ball joints that are respectively connected to both ends of the power steering cylinder, And a tie rod that connects the knuckle arm and the ball joint. The front axle case according to claim 1.

3. Further comprising a covering portion that covers the insertion portion and the housing portion, The covering portion also serves as an axle case support member that supports the front axle case to be rollable left and right with respect to the vehicle body frame. The front axle case according to claim 1.

4. The front axle case according to any one of claims 1 to 3, and an input shaft that is accommodated in the insertion portion or the accommodation portion of the front axle case and transmits power to the drive shaft inside the main body case, the work vehicle comprising the input shaft.

Images