JPH1178925A - Traveling vehicle for working - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an inconvenience that a steering angle varies largely from occurring when an untransmitting condition occurs during speed change by providing a steering transmission mechanism to change the speed of the input rotation of a power steering unit between a steering wheel and a power steering unit. SOLUTION: A traveling vehicle for working provided with a fully hydraulic steering mechanism is structured so that a steering transmission mechanism 29 is provided between a steering wheel and a power steering unit. Also the transmission mechanism 29 is provided with a differential mechanism 30 which meshes a pair of pinion gears 30c between a pair of side gears 30a and 30b and an input shaft 31 which transmits the rotation of a steering wheel to a pinion shaft 30d which rotatably supports the pair of pinion gears 30c. Then the input rotation of the power steering unit is doubled transmittable and, even if an untransmitting condition occurs during transmission, an inconvenience that steering angle varies largely can be avoided based on a kick back.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a working vehicle such as a tractor having a fully hydraulic steering mechanism.

[0002]

2. Description of the Related Art Generally, a working vehicle of this type is provided with a steering mechanism for steering a front wheel in accordance with a rotation operation of a steering wheel, and a front wheel steering amount (front wheel operation amount) with respect to an operation amount (operation speed) of the steering wheel. (Steering speed) is set to be substantially constant, so that in a headland turn or the like where a small turn is required, it is necessary to quickly operate the steering wheel.

[0003]

[Problems to be Solved by the Invention]
As disclosed in JP-A-43658, the front-wheel steering speed can be changed with respect to the operating speed of the steering wheel, or JP-A-8-26126 (or JP-A-8-31010).
No. 428) has already been proposed that automatically (or switches) steer the front wheels to the maximum turning angle when the body turns. However, the former is a mechanical steering mechanism in which kickback (rotational load transmitted from the steered wheels to the steering wheel) is likely to be generated, and a gear transmission mechanism is interposed between the mechanical steering mechanism and the kick generated during gear shifting (transmission blank state). The front wheel steering angle may change significantly based on the back, while the latter employs a fully hydraulic steering mechanism, but the steering wheel operation during the turning of the aircraft may be restricted.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been made for the purpose of solving these problems. In the present invention, the rotation of a steering wheel is input to a power steering unit. In a working vehicle equipped with a fully hydraulic steering mechanism that operates a hydraulic cylinder for steering with a discharge hydraulic pressure of a power steering unit according to an input rotation, an input rotation of the power steering unit is provided between the steering wheel and the power steering unit. This is provided with a steering transmission mechanism for shifting the speed. In other words, if the steering speed change mechanism is shifted to the speed increasing side, it is possible to make a small turn of the aircraft with a small amount of operation, but the steering speed change mechanism is provided in the operation path of the fully hydraulic steering mechanism with little kickback. Since it is interposed, there is no inconvenience that the steering angle greatly changes based on kickback even if the transmission blank state occurs during the provisional gear shift. Further, even during the turning of the body (in a speed-up state), the steering hydraulic cylinder is operated via the power steering unit, so that the disadvantage that the operation of the steering wheel is restricted during the turning of the body can be avoided. . Further, in the above, a turning operation judging means for judging a turning operation of the body during work traveling, and a steering automatic transmission means for automatically shifting the steering speed change mechanism to the speed increasing side based on the turning operation judgment. It is provided. In other words, there is no need to shift the steering transmission mechanism when turning the aircraft,
The operability at the time of turning the aircraft can be further improved by reducing the operation labor of the operator.

[0005]

Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of a tractor, and an elevating link mechanism 4 suspended by a lift arm 3 via a pair of left and right lift rods 2 is connected to a rear portion of the traveling body 1. A working machine 5 such as a rotary is detachably attached to a tip of the lifting link mechanism 4. The working machine 5 moves up and down with the hydraulic operation of the lift cylinder 6 for vertically swinging the lift arm 3, and also with the hydraulic operation of the lift rod cylinder 7 interposed between the left and right lift rods 2. All of these basic configurations are conventional.

Reference numeral 8 denotes a transmission provided in the traveling body 1. The transmission 8 includes a main clutch mechanism 9 for intermittently inputting power input from an engine (not shown), and a static transmission for continuously changing input power. Hydraulic continuously variable transmission (HST) 10, PTO that changes the power not passing through continuously variable transmission 10 and transmits it to PTO shaft 11
A speed change mechanism 12, an auxiliary speed change mechanism 13 for shifting the speed of the traveling power output from the continuously variable speed change mechanism 10, and the like again are incorporated. The traveling power output from the auxiliary transmission mechanism 13 is directly transmitted to a rear wheel differential mechanism (not shown) in a rear axle case (not shown), and also passes through a front wheel transmission mechanism 14 described later. Power is transmitted to a front wheel differential mechanism (not shown) in a front axle case (not shown), and a transmission brake path from the rear wheel differential mechanism to the left and right rear wheels 15 is provided with a side brake mechanism (not shown). ), So-called brake turning that turns while braking the rear wheel 15 on the inner wheel side can be performed.

[0007] The front wheel transmission mechanism 14 includes a front wheel drive gear 1.
6 and a front wheel drive shaft 17, a ball clutch mechanism 18, a switching sleeve 20 for holding the ball clutch mechanism 18 in an engaged state by the urging force of an elastic machine 19, and a small diameter constantly meshing with the front wheel drive gear 16. A front-wheel transmission shaft 21 having a gear 21a; a front-wheel transmission gear 22 that always meshes with a large-diameter gear 21b of the front-wheel transmission shaft 21; a wet multi-plate interposed between the front-wheel transmission gear 22 and the front-wheel drive shaft 17 It is composed of a clutch mechanism 23 and the like. Normally, the power of the front wheel drive gear 16 is directly transmitted to the front wheel drive shaft 17 because the ball clutch mechanism 18 is in the engaged state. When the ball clutch mechanism 18 is switched to the disengaged state, the wet multi-plate clutch mechanism 23 is switched to the engaged state. The power of the gear 22 is transmitted to the front wheel drive shaft 17. That is, since the rotation of the front wheels can be changed to approximately double speed based on the hydraulic pressure switching operation of the switching sleeve 20, so-called front wheel double-speed turning, in which the front wheels 24 turn while increasing the speed, can be performed.

Reference numeral 25 denotes an all-hydraulic steering mechanism. The all-hydraulic steering mechanism 25 inputs the rotation of a steering wheel 26 to a power steering unit (orbit roll) 27 and outputs a power steering unit corresponding to the input rotation. The hydraulic oil for steering 28 is operated by the discharge oil 27. That is, the power steering unit 27 includes the hydraulic pump P
A control valve (rotary valve) 27a that switches an oil passage connecting the hydraulic cylinder 1 (or hydraulic tank) and the steering hydraulic cylinder 28 according to the input rotation direction and adjusts the flow rate according to the input rotation amount (rotation speed). Since it is incorporated, the front wheels 24 can be steered with a small operating force, and so-called kickback can be reduced as compared with a mechanical steering mechanism. Reference numeral 27b denotes a metering device incorporated in the power steering unit 27. The metering device 27b functions as a flow rate measuring hydraulic motor that constantly measures the flow rate and feeds it back to the control valve 27a. It functions as a manual hydraulic pump that supplies manual hydraulic oil supply to the steering hydraulic cylinder 28.

Reference numeral 29 denotes a steering transmission mechanism interposed between the steering wheel 26 and the power steering unit 27. A case 29a of the steering transmission mechanism 29 has a pair of pinion gears between a pair of side gears 30a and 30b. Differential mechanism 3 meshed with 30c
0, an input shaft 31 for transmitting the rotation of the steering wheel 26 to a pinion shaft 30d rotatably supporting a pair of pinion gears 30c, a clutch pawl 31a formed on the input shaft 31, and a power steering unit for transmitting the power of one side gear 30a. 27, a cylindrical shaft 30e formed integrally with the other side gear 30b, a switching sleeve 33 spline-fitted to the outer periphery of the cylindrical shaft 30e, and a clutch formed on the switching sleeve 33. Nail 3
3a, the clutch pawl 33a is connected to the clutch pawl 3 of the input shaft 31.
An ammunition device 34 for urging the switching sleeve 33 in the direction of meshing with 1a, a wet multi-plate brake mechanism 35 interposed between the case 29a and the cylindrical shaft 30e, and the like are incorporated. Normally, the cylindrical shaft 30e rotates integrally with the input shaft 31 based on the engagement of the clutch claws 31a, 33a, so that the pinion gear 30c rotates integrally with the input shaft 31 in a non-rotating state to rotate the output shaft 32 into the input shaft. While rotating at the same speed as 31,
When the switching sleeve 33 is slid downward by hydraulic pressure against the ram 34, the engagement of the clutch claws 31a, 33a is released, and the wet multi-plate brake mechanism 35 brakes the rotation of the cylindrical shaft 30c. The pinion gear 30c
Are rotated integrally with the input shaft 31 in the rotation state, and the output shaft 32 is rotated.
Is rotated at twice the speed of the input shaft 31. That is,
Since the input rotation of the power steering unit 27 can be shifted to double speed based on the hydraulic pressure switching operation of the switching sleeve 33, the aircraft can be turned slightly with a small amount of operation. Since the back is provided on the operation path of the all-hydraulic steering mechanism 25 with a small amount of back, even if a transmission blank state occurs during the provisional gear shifting, it is possible to avoid a disadvantage that the steering angle largely changes based on the kick back. It has become.

Reference numeral 36 denotes a steering speed increasing electromagnetic valve for operating the wet multi-plate brake mechanism 35 (switching spool 33).
From the hydraulic pump P1 to the power steering unit 2
7 is interposed in a diverting oil passage connecting the oil passage to the wet multi-plate brake mechanism 35, and further shunts the oil passage from the steering speed increasing electromagnetic valve 36 to the wet multi-plate brake mechanism 35. The wet multi-disc clutch mechanism 23 is connected to the front end, and a front wheel speed increasing electromagnetic valve 37 is interposed in the connection oil passage. In the drawings, P2 is a hydraulic pump for supplying hydraulic pressure to the lift cylinder 6 and the lift rod cylinder 7, 38 is a lift cylinder electromagnetic valve unit for switching the operation of the lift cylinder 6, and 39 is a lift for switching the operation of the lift rod cylinder 7. Electromagnetic valve for rod cylinder.

Further, reference numeral 40 denotes a control unit constituted by using a microcomputer, and on the input side of the control unit 40, a lift arm sensor 41 for detecting a swing angle of the lift arm 3, left and right side brakes A pair of left and right brake detection switches 42L, 42R for detecting operation, respectively.
A pair of left and right turn detection switches 43L and 43R for detecting the turning operation of the body based on the front wheel steering angle, an auxiliary shift detection switch 44 for detecting the high speed shift state of the auxiliary transmission mechanism 13, a steering mode switch 45 for switching the steering mode, and the like. On the other hand, the output side is connected to the steering speed increasing electromagnetic valve 36, the front wheel speed increasing electromagnetic valve 37, the steering speed increasing lamp 46 for notifying the steering speed increasing state, and the like. In other words, the control unit 40 performs “front wheel speed-up control” for shifting the front wheel transmission mechanism 14 based on the determination of the turning operation during non-high-speed running, and “steering speed-up” for shifting the steering transmission mechanism 29 according to the steering mode. The control procedure of “steering speed increase control”, which is a main part of the present invention, will be described below with reference to flowcharts.

In the "steering speed-up control", it is first determined whether or not the sub-transmission mechanism 13 is in a high-speed shifting state. If the determination is YES, regardless of the subsequent steps, the steering speed-up electromagnetic is determined. While turning off the valve 36,
If the determination is NO, the switching position of the steering mode switch 45 is determined. When the steering mode is the fixed speed increasing mode, the steering speed increasing electromagnetic valve 36 and the steering speed increasing lamp 46 are always turned on regardless of whether or not the vehicle is turning. In some cases, a one-brake operation (a brake turning state in which only one of the left and right side brakes is operated) is determined, and only when the determination is YES, the steering speed increasing electromagnetic valve 36 and the steering speed increasing lamp 46 are turned ON. It is designed to switch.
Further, in the case of the front wheel speed increase interlocking mode, the front wheel speed increase determination (turn detection switch 43) of the “front wheel speed increase control” is performed.
L, 43R), the steering speed increasing electromagnetic valve 36 and the steering speed increasing lamp 46 are switched ON only when the judgment is YES. In the state (working state), the steering speed increasing electromagnetic valve 36 is maintained in the OFF state.

In the construction as described above, the rotation of the steering wheel 26 is input to the power steering unit 27, and the hydraulic cylinder 28 for steering is operated by the discharge hydraulic pressure of the power steering unit 27 according to the input rotation.
And a steering transmission mechanism 2 for shifting the input rotation of the power steering unit 27 between the steering wheel 26 and the power steering unit 27.
9, it is possible to make a small turn of the body with a small amount of operation by operating the steering transmission mechanism 29 to increase the speed, and the all-hydraulic steering transmission mechanism 25 is a so-called kickback. Therefore, even if a temporary command transmission blank state occurs during the steering shift, there is no inconvenience that the steering angle greatly changes based on kickback. In addition, even when the vehicle is turning (in a speed increasing state), the steering hydraulic cylinder 28 is operated via the power steering unit 27, so that the inconvenience of restricting the operation of the steering wheel 26 during the vehicle turning is also avoided. be able to.

Further, the turning operation (brake turning or the front wheel speed-up turning) of the machine body during work traveling (non-road running) is determined, and the steering transmission mechanism 29 is automatically shifted to the speed increasing side based on the determination. Therefore, there is no need to perform a shift operation of the steering transmission mechanism 29 during the turning of the body, and as a result, the operation labor of the operator can be reduced and the operability during the turning of the body can be further improved.

In automatically shifting the steering transmission mechanism 29 in conjunction with the front wheel speed increase, if the work implement 5 is lowered, it is determined that work is being performed (tiling) and the automatic shift is stopped. Therefore, it is possible to avoid a disadvantage that the working accuracy is reduced based on the automatic shifting operation of the steering shift mechanism 29.

In the present embodiment, a plurality of steering modes (fixed speed increase, brake turning interlock, front wheel speed interlock) are set, and the mode is switched by the steering mode changeover switch 45. There is an advantage that can be handled.

Further, since the steering speed change mechanism 29 performs a speed change based on the rotational braking of the wet multi-plate brake 35, a smooth speed change with less shock can be performed. Since the power transmission is performed via the clutch claws 31a and 33a that maintain the meshing state, the rotation of the steering wheel 26 is input to the power steering unit 27 even when the wet multi-plate brake 35 does not operate due to some abnormality. be able to.

The present invention is, of course, not limited to the above-described embodiment. For example, each speed ratio (normal speed ratio, speed-up speed ratio) of the steering speed change mechanism 29 may be freely set. Can be. Further, in the steering mode, a speed-up OFF mode without shifting to a speed-up side, P
A PTO interlocking mode or the like in which the steering speed change mechanism 29 is automatically shifted to the speed increasing side based on the TO power OFF determination (work interruption determination) may be added.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a sectional view of a transmission.

FIG. 3A is a cross-sectional view illustrating a non-speed-up state of the front wheel transmission mechanism, and FIG. 3B is a cross-sectional view illustrating a speed-up state.

FIG. 4 is a schematic view of a fully hydraulic steering mechanism.

FIG. 5 is a sectional view of a steering transmission mechanism.

FIG. 6 is a hydraulic circuit diagram showing the entire hydraulic mechanism.

FIG. 7 is a block diagram showing input and output of a control unit.

FIG. 8 is a flowchart of “steering speed increase control”.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 25 Full hydraulic steering mechanism 26 Steering wheel 27 Power steering unit 28 Hydraulic cylinder for steering 29 Steering speed change mechanism 36 Electromagnetic valve for increasing steering speed 40 Control unit

Claims (2)

[Claims] 1. A work vehicle having a full hydraulic steering mechanism for inputting rotation of a steering wheel to a power steering unit and operating a hydraulic cylinder for steering with a discharge hydraulic pressure of the power steering unit according to the input rotation. A work vehicle having a steering transmission mechanism interposed between the steering wheel and the power steering unit for shifting the input rotation of the power steering unit. 2. A steering automatic transmission according to claim 1, further comprising: a turning operation judging means for judging a turning operation of the vehicle body during work traveling; and a steering automatic shifting operation for automatically shifting a steering speed change mechanism to a speed increasing side based on the turning operation judgment. Work vehicle provided with means.