JPH0619391Y2 - Work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a working vehicle.

(Prior Art) A vehicle in which front wheels and rear wheels are drive wheels and the rear wheels can be steered in conjunction with a steering wheel is a front-mounted type in which a work machine such as a mower is mounted on the front side of the vehicle body. Widely used.

(Problems to be solved by the invention) In this type of vehicle, since the turning radii of the front wheels and the rear wheels are different at the time of turning, the rear wheels serve as a brake for the front wheels,
Despite being a rear-wheel steering type, the turning radius could not be reduced. Further, since the rear wheel serves as a brake, there is a drawback that the rear wheel slips on the ground and damages the lawn if it is a lawn.

The present invention has been made in view of such conventional problems, and an object thereof is to enable turning with a small radius without causing wheel slippage or the like.

(Means for Solving Problems) The present invention is a vehicle body 1 having a pair of left and right front wheels 6 and rear wheels 9.
A control device 83 is provided on the upper portion of the vehicle 1 and a working machine 89
In the working vehicle in which the front wheel 6 and the rear wheel 9 are both driven and the rear wheel 9 is steerable, the following technical means are taken to achieve the above-mentioned object.

That is, according to the present invention, the control device 83 is arranged near the front wheel 6 in the front part of the vehicle body 1, a pair of left and right rear wheels 9 are provided near the substantially central portion between the front wheels 6, and between the rear wheels 9. A pair of left and right rear wheels 9 is steerably arranged around the central axis of the central portion, a front wheel clutch 33 is provided in the power transmission system of the front wheels 6, and a detection means 108 for detecting the steering angle of the rear wheels 9 is provided. , The front wheel clutch 33 is interlocked with the detection means 108 when the rear wheel 9 becomes equal to or larger than the predetermined steering angle α
It is characterized in that an interlocking means 111 for cutting off is provided.

(Operation) When the rear wheel 9 is steered by the steering wheel 83 at a predetermined steering angle α or more, the detection means 108 operates, and the clutch via the interlocking means 111.
Turn off 33 to cut off power transmission to the front wheels 6. Therefore, after that, the vehicle turns by the driving force of the rear wheels 9.

(Embodiment) The present invention will be described in detail below with reference to the illustrated embodiment.
1 to 3, a vehicle body 1 is a member 2 such as a square tubular member.
Is assembled into a rectangular frame shape. In the vehicle body 1, an engine 3 and a hydrostatic transmission 4 are arranged side by side in the front-rear center part, and a pair of left and right front wheels 6 are provided in the front part via a front axle 5.
And a pair of left and right rear wheels 9 are suspended in the rear through a rear axle 8 of the rear wheel drive device 7, the pair of left and right rear wheels 9 are close to each other, and a substantially central portion between the front wheels 6 is provided. It is located in. The engine 3 is supported by the vehicle body 1 via a vibration isolator, and the crankshaft protruding forward from the engine 3
A traveling pulley 11 and a PTO pulley 12 are provided at 10. A radiator 13, a cooling fan 14, and an oil cooler 15 are arranged behind the engine 3.

The transmission 4 is supported by the vehicle body 1 via a vibration-proof material, and a belt is attached to the input shaft 16 protruding forward from the transmission 4.
A pulley 18 that interlocks with the traveling pulley 11 of the crankshaft 10 via 17 and a cooling fan 19 that blows air to the transmission 4 are provided. On the rear side of the transmission 4, a deceleration case 21 having a reduction gear 20 incorporated therein is vertically mounted so as to project downward.

The speed reducer 20 is an output shaft of the transmission 4 as shown in FIG.
First to third shafts 23, 24, 25 arranged in parallel below 22
The first shaft 23 projects rearward from the reduction gear case 21 for driving rear wheels, and the third shaft 25 projects forward from the reduction gear case 21 for driving front wheels. First shaft 23 is gear 26,2
The output shaft 22 of the transmission 4 is decelerated through 7 and the second shaft 24 is connected to the first shaft 23 via the gears 28 and 29 and the third shaft 25.
Are decelerated and interlocked with the second shaft 24 via the gears 30 and 31, respectively. Therefore, as they are separated from the output shaft 22 in the downward direction, the rotational speeds thereof are slowed. Gear 28 on the first shaft 23
Is free to rotate and is a shifter clutch for the occlusal portion 32.
It can be interlocked with and released from the first shaft 23 by engaging / disengaging operation of 33. The shifter clutch 33 can be turned on and off by a switching lever 36 via a lever shaft 34 inserted into the deceleration case 21 and a shift fork 35 at its inner end.

The third shaft 25 has a larger shaft diameter than the first shaft 23 and the second shaft 24, and extends forward through the lower part of the transmission device 4. At the front end thereof, the bevel gear of the front wheel differential device 37 is provided. Bite.
The front wheel differential device 37 is mounted on the lower side of the vehicle body 1 in front of the transmission 4 as shown in FIGS. 1 and 3.
It is provided so as to be largely deviated from one of the left and right central portions to one side. The front wheel differential device 37 is for driving the front wheel 6 with the power from the third shaft 25 via the pair of left and right front axles 5. Since the front wheel differential device 37 is laterally offset, the front axle 5 on the long axis side is supported by the vehicle body 1 via the bearing 40. A PTO shaft 41 is inserted in the front-rear direction in the case of the front wheel differential device 37, and a belt 42 is attached to the rear end of the PTO shaft 41.
A pulley 43 that is interlocked with the PTO pulley 12 is fixedly installed.

The rear wheel drive device 7 is supported by a frame-shaped rear frame 44 that projects rearward from the rear end of the vehicle body 1. As shown in FIGS. 5 and 6, the rear wheel drive system 7 has a gear transmission mechanism incorporated in an upper case 45, an inner cylinder 46, an outer cylinder 47 and a lower case 48. The upper case 45 is attached to the rear frame 44 via a pair of left and right mounting portions 49. The upper case 45 has an input shaft 50, a bevel pinion shaft 51, and a bevel gear that links these.
52,53 are assembled. The input shaft 50 is projected from the upper case 45 obliquely forward in the left-right direction, and is connected to the first shaft 23 via a universal joint 54 at the front end and a transmission shaft 55. A brake 57 is provided on the rear side of the first shaft 23.

The bevel pinion shaft 51 is provided in the vertical direction, and an inner cylinder 46 is attached to the lower side of the upper case 45 concentrically with the bevel pinion shaft 51 by a bolt 58 so as to project downward. The inner cylinder 46 has a large diameter portion 59 and a small diameter portion 60 vertically, and a bevel gear 53 is rotatably supported at the upper end of the large diameter portion 59 via a bearing 61. The outer cylinder 47 is rotatably fitted onto the inner cylinder 46 via a bush 62, a bearing 63 and the like, and is retained by a retaining ring 64 at the lower end of the inner cylinder 46 so as not to be pulled out downward.
The lower case 48 incorporates the rear wheel differential device 65, is attached to the lower end of the outer cylinder 47 with bolts 66, and the bearing cases 67 are attached to the left and right sides of the lower case 48 with bolts. The rear wheel differential device 65 is supported by a bearing case 67 via a bearing 68, and its bevel gear 69 is meshed with a bevel pinion 70 at the lower end of the bevel pinion shaft 51. The rear axle 8 protruding left and right from the rear wheel differential device 65 is
The rear wheel 9 is supported by a bearing case 67 via a bearing 71, and the rear wheel 9 is attached to the outer end of the rear axle case 67. In addition,
The rear wheel 9 is provided close to the lower case 48 so that the bearing case 67 fits substantially inside the tire rim 72. The tread between the left and right rear wheels 9 is about 1 / th of the tread between the left and right front wheels 6. It is about 3.

At the upper end of the outer cylinder 47, as shown in FIGS. 5 and 6,
A sprocket 74 for steering is provided near the upper portion of the rear wheel 9 via a flange portion 73 extending outward. The sprocket 74 is detachably attached to the flange portion 73 with a bolt 75.

Reference numeral 76 is a hydraulic cylinder for steering, which is attached to the lower rear of the rear frame 44, and both ends of a piston rod 77 protruding left and right from the hydraulic cylinder 76 are connected to both ends of a chain 78 wound around a sprocket 74. Has been done. Therefore, when the piston rod 77 of the hydraulic cylinder 76 reciprocates in the left-right direction, the outer cylinder 47 is inserted through the chain 78 and the sprocket 74.
By turning around 46, the rear wheel 9 can be steered within a range of approximately ± 90 degrees. In addition, 79 is a guide sprocket, a sprocket
It is supported on the rear frame 44 on both sides of the rear part of the sprocket 74 so as to secure the winding of the churn 78 on the 74.

As shown in FIGS. 5 and 6, the sprocket 74 is formed with a long hole 103 centered on the bevel pinion shaft 51, and the pin 105 at one end of the detection rod 104 is slidable in the long hole 103. Has been inserted. The other end of the detection rod 104 is connected to the vehicle body 1
Is connected to a lever 107 that is pivotally supported by a pivot 106. The elongated hole 103, the detection rod 104, the pin 105, and the lever 107
A detector 108 for detecting the steering angle of the rear wheels 9 is constituted by the above. The lever 107 is a lever 109 fixed to the pivot 106.
It is connected to the lever 36 through the interlocking means 111 composed of the rod 110 and the rod 110, and when the detecting means 108 exceeds the predetermined steering angle α, the shifter clutch 33 is disengaged to disconnect the power of the power transmission system to the front wheels 6. It has become. The predetermined steering angle α
Is set to a steering angle when the turning radius L outside the rear wheel 9 is slightly larger than the turning radius 1 from the turning center O outside the front wheel 6, as shown in FIG.

Reference numeral 80 is a step support frame projecting forward from the vehicle body 1, 81 is a step plate mounted on the step support frame 80, 82 is a handle post, and 83 is a steering handle. A control unit 84 for steering controls the hydraulic cylinder 76 in conjunction with the handle 83. Reference numeral 85 is a floor cover mounted on the vehicle body 1 and covers the pulleys 11, 12 and the like. 86 is a driver's seat, 87 is a front wheel fender, and 88 is a safety frame.

89 is the front mower, below the mower deck 90, the vertical axis
Three discs 92 that rotate about 91 are provided, and a cutter 93 is pivotally attached to each of the discs 92 so that the discs 92 can rotate to cut grass. The mower deck 90 has a gauge wheel 94 for adjusting the cutting height and other limit gauges 95, and is attached to the vehicle body 1 by two links 96 extending forward from the vehicle body 1 and can be lifted and lowered by expanding and contracting a hydraulic cylinder 97. Is. Each disk 92 is a PT
It is rotationally driven by the power transmitted from the O shaft 41 through the universal joint shaft 98.

Reference numeral 99 denotes a grass container, which is arranged on the rear frame 44. The grass container 99 is attached to a column 100 standing on the rear portion of the vehicle body 1. The grass container 99 is made of punching metal, steel, or the like. Reference numeral 101 is a duct for feeding the grass cut by the mower 89 to the grass container 99. The duct 101 is connected to the center of the rear part of the mower deck 90, and is connected to the grass container 99 from below the front axle 5 and behind one front wheel 6. 102 is a fuel tank.

In the above configuration, during the mowing work, the PTO pulley 12 and the belt 4 are driven by the power from the crankshaft 10 of the engine 3.
2, each disk 92 of the mower 89 is rotationally driven through the PTO shaft 41 and the universal joint shaft 98, and is cut by the cutter 93. Then, the cut grass is sent to the grass collecting container 99 through the duct 101 and collected in the grass collecting container 99.

At the time of traveling, after shifting the power from the engine 3 to an appropriate speed by the transmission 4, the front wheel 6 is driven from the third shaft 25 of the reduction gear 20 through the front wheel differential device 37 and the front axle 5.
Transmission from the first shaft 23 of the reduction gear 20 to the input shaft 50 of the rear wheel drive device 7 via the transmission shaft 55 and the universal joint 54, and the rear wheel drive device 7 drives the rear wheel 9. In this case, since the wheel diameter of the front wheel 6 is larger than the wheel diameter of the rear wheel 9, the front wheel 6 side decelerates sufficiently through the gears 26, 27, 28, 29, 30, 31 of the reduction gear 20 to reduce the rotation speed. High torque power is transmitted from the third shaft 25 to the front wheel differential device 37, and the shaft diameter of the third shaft 25 is large. On the other hand, on the rear wheel 9 side, power is transmitted from the first shaft 23 as high-speed low-torque power only by decelerating with the gears 26, 27, and therefore, the shaft diameter of the first shaft 23 is small.

In the rear wheel drive device 7, the input shaft 50, the bevel gears 52, 53,
Bevel pinion shaft 51, bevel pinion 70, bevel gear
Power is transmitted to the rear wheel differential device 65 via 69, and the rear wheels 9 are driven via the rear axle 8. When traveling straight ahead, the rotation speed of the rear wheel 9 is large by the difference in wheel diameter between the front wheel 6 and the rear wheel 9, and the peripheral speeds of both are substantially the same.

When the steering wheel 83 is operated during steering, the hydraulic cylinder 76 operates in the left-right direction via the control unit 84, and the piston rod 77 rotates the outer cylinder 47 side around the inner cylinder 46 via the chain 78 and sprocket 74, The rear wheels 9 rotate in the steering direction while still in the driving state. By steering the rear wheels 9 in this manner, it is possible to steer the vehicle at a small steering angle, and therefore it is very convenient for work around trees and the like.

When the rear wheel 9 is within the predetermined steering angle α, only the pin 105 slides in the elongated hole 103 of the sprocket 74, and the detection rod
104 etc. do not detect. When the rear wheel 9 becomes a predetermined steering angle α or more, the pin 105 engages with one end of the long hole 103 and the detection rod 104 is pulled, so that the levers 107 and 109 rotate around the pivot 106 in the direction indicated by the arrow a in FIG. The lever 36 and the shift fork 35 rotate about the lever shaft 34 in the direction of arrow b in FIG. 4 via the rod 110. Therefore, the shift clutch 33 is disengaged from the meshing portion 32 of the gear 28, so that the transmission of power to the front wheels 6 is interrupted and the rear wheels 9 are driven to make a turn, and both the front wheels 6 and the rear wheels 9 slip. Without turning, you can swivel quickly and smoothly. In particular, since the power on the front wheel 6 side is cut off, the front wheel 6 side does not advance greatly. Therefore, if the steering angle of the rear wheel 9 is increased, the turning center is near the inner front wheel 6 or between the left and right front wheels 6. Thus, it is possible to make a sharp turn with a small turning radius.

The detecting means 108 and the interlocking means 111 may be electrically configured.

The steering mechanism has an outer cylinder as shown in FIGS. 8 and 9.
Two upper and lower sprockets 113 and 114 are fixed to the upper end of 47, and two chains 115 and 116 are wound around this,
The end opposite to the piston rod 77 may be fixed to the sprockets 113 and 114 with metal fittings 117 and 118.

Alternatively, an arm may be provided at the upper end of the outer cylinder 47, and the outer cylinder 47 can be rotated by the hydraulic cylinder 76 via this arm.

The upper case 45 and the inner cylinder 46, and the lower case 48 and the outer cylinder 47 may be integrally formed.

(Effect of the Invention) According to the present invention, the detecting means 108 operates when the rear wheel 9 becomes the predetermined steering angle α or more, and the clutch 33 is operated via the interlocking means 111.
Since the power is cut off and the power transmission to the front wheels 6 is cut off, the operation at the time of turning is smooth and the wheels do not slip. Further, at the time of this turning, the front wheels 6 are in the non-driving state and the rear wheels 9 are in the driving state. Further, since the rear wheels 9 are arranged close to the substantially central portion between the front wheels 6, it is possible to make a sharp turning with a small radius. .

Further, when making a sharp turn, the state of the front-mounted work machine 89 is such that the operation device 83 is provided near the front wheel 6 in the front part of the vehicle body 1, so that a stable turn can be made by visually recognizing the work situation and maneuverability. There is an advantage that can be improved.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is an overall plan view, FIG. 2 is a side view of the same, FIG. 3 is a sectional front view thereof, and FIG. 4 is a sectional view of a speed reducer. FIG. 5 is a sectional side view of a rear wheel suspension portion, FIG. 6 is a sectional view of a rear wheel drive device, FIG. 7 is an operation explanatory view, FIG. 8 is a sectional side view of another steering mechanism, and FIG.
The figure is a schematic perspective view of the same. 1 ... Body, 3 ... Engine, 4 ... Transmission, 6 ...
Front wheels, 7 ... rear wheel drive device, 9 ... rear wheels, 20 ... reduction gear, 21 ... reduction gear case, 33 ... shifter clutch, 37 ...
Front wheel differential device. 83 …… Handle, 108 …… Detecting means, 111
…… Interlocking means.

Claims (1)

[Scope of utility model registration request] 1. A control device (83) is provided on a vehicle body (1) having a pair of left and right front wheels (6) and rear wheels (9), and a working machine (89) is provided at a front end portion of the vehicle body (1). In a working vehicle in which both the front wheels (6) and the rear wheels (9) are driven, and the rear wheels (9) are steerable, the control device (83) is attached to the front wheels of the front part of the vehicle body (1) ( 6) Placed in the vicinity, close to the center of the front wheels (6), the pair of left and right rear wheels (9)
And a pair of left and right rear wheels (9) are steerably arranged around the longitudinal center of the substantially central portion between the rear wheels (9), and the front clutch (33) is provided in the power transmission system of the front wheels (6). ) Is provided, and detection means (108) for detecting the steering angle of the rear wheel (9) is provided, and the rear wheel (9) has a predetermined steering angle (α).
A working vehicle characterized by comprising an interlocking means (111) for disengaging the front wheel clutch (33) in association with the detecting means (108) when the above is reached.