JP3658914B2 - Steering device for work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a steering device for a work vehicle of a tractor or a rice transplanter.
[0002]
[Prior art and problems]
Conventionally, in a work vehicle, like a tractor disclosed in Japanese Patent Laid-Open No. 8-156812, in order to reduce steering operation during pillow turn during tillage work, the front wheel breaks with respect to the steering handle operation amount. A device provided with a steering device capable of changing the angle is known.
[0003]
[Problems to be solved by the invention]
However, what is shown in the above publication is a configuration in which the operation amount of the steering device is switched by a mode changeover switch. Therefore, when the small turn and the large turn are repeatedly required depending on the shape of the field, the turn It was necessary to switch the mode changeover switch every time to increase the steering amount of the front wheels or to change it to normal. For this reason, the operability of the tractor is impaired.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has taken the following technical means. That is, an operation having brake pedals 2 and 2 that brake the left and right drive wheels 1 and 1 independently, and a steering device 5 that can change the operation amount of the steering wheels 4 and 4 with respect to the operation amount of the steering handle 3. In the vehicle, a detecting means 6 for detecting the depression operation of the brake pedals 2 and 2 and a means 19s (23s) for detecting the height of the work implement 20 are provided, and the depression operation of the brake pedal 2 is detected and the work implement is detected. When the height of 20 is equal to or greater than a certain level, the steering device 5 is configured to be able to increase the steering amount of the steering wheels 4 and 4 with respect to the operation amount of the steering handle 3, and the steering amount is increased . Is configured to be released in conjunction with the lowering operation of the work machine 20 .
[0005]
【The invention's effect】
As a result, it is determined by the depressing operation of the brake pedals 2 and 2 that the operator makes a small turn, and the operation of the steering handle 3 is performed only when the depressing operation is detected and the height of the work implement 20 is equal to or higher than a certain level. Since the turning angle of the steered wheels 4 and 4 can be increased with respect to the amount, when the amount of steered wheels 4 and 4 increases when the turning amount of the steered wheels 4 and 4 increases, such as when turning a large turn or after the turn is finished, Steering operation is possible and the operability of the work vehicle is improved.
Further, since the state in which the steering amount is increased is detected and released by detecting the lowering operation of the work implement 20, for example, the tractor or the like reverses the work implement 20 while raising the work implement 20 after turning. Even when steering to the heel, the steered wheels 4 and 4 can be steered with few steering operations, and the apparatus can be operated in a state suitable for farm work.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an agricultural tractor (hereinafter referred to as a tractor 10) which is a work vehicle will be described as an embodiment of the invention. The overall configuration of the tractor 10 will be described.
The tractor 10 is provided with an engine 12 inside a bonnet 11 at the front of the airframe, and a clutch housing, a transmission case 13, a rear transmission case 14 and the like are integrally connected from the engine 12 to constitute a main frame of the vehicle body. ing. Further, front wheels 4 and 4 that are steered wheels are provided on the lower left and right sides of the engine 12, and rear wheels 1 and 1 that are drive wheels are provided on the left and right sides of the rear mission case 13. The front wheels 1 and 1 are provided with a front wheel turning angle sensor 9 for detecting the steering angle, and the steering of the tractor 10 is detected.
[0007]
A handle post 15 is provided on the rear surface of the bonnet 11, a forward / reverse switching lever 16 is provided on the side of the bonnet 11, and the steering handle 3 protrudes above the post 15. Then, the front wheels 4 and 4 are steered via a power steering device 5 which is a steering device to be described later by rotating the steering handle 3. A forward switch 16F that is turned on when pushed forward and switches a switching control valve 51, which will be described later, is turned on the rotation base of the forward / reverse switching lever 16, and is switched on when switched backward to switch the control valve 51. A reverse switch 16R is provided. Brake pedals 2 and 2 for braking the left and right rear wheels 1 and 1 are provided below the handle post 15. Brake switches 6 and 6 as means for detecting the depression operation are provided on the left and right rotation bases of the brake pedals 2 and 2, respectively, and are turned on when the depression is performed.
[0008]
The vicinity of the cockpit 17 of the tractor 10 will be described. At the side of the cockpit 17, a control switch 8 for turning on and off the control for changing the operation amount of the front wheels 4 and 4 when turning, A position lever 19 that is an operation unit of the work machine 20 is provided. Further, a PTO on / off switch 22 for turning on and off the rotation of a PTO shaft 21 that drives a work machine 20 described later is provided. A potentiometer 18s is provided at the rotation base of the speed change lever 18, and the operator's lever operation is input to the controller 7 which is a control section provided below the cockpit 17. The transmission cases 13, 14 are controlled according to the speed change operation. The transmission 33 is switched. Further, a potentiometer 19s is also provided at the rotation base of the position lever 19, and the controller 7 detects an operation angle of the lever 19, and a set angle of a lift arm angle sensor 23s to be described later coincides accordingly. Further, solenoids 66s and 67s of a proportional pressure control valve for raising and lowering the work implement are excited to drive a cylinder 24 described later.
[0009]
The configuration of the rear part of the tractor 10 will be described. A cylinder case 25 is provided at the rear upper part of the rear mission case 13. The cylinder case 25 has a built-in working machine elevating cylinder 24 and is configured to vertically rotate lift arms 26, 26 supported on the left and right of the case 25 by the expansion and contraction of the piston of the elevating cylinder 24. A lift arm angle sensor 23 s serving as a work implement position detecting means is provided at the rotation base of the lift arm 26 so that the lift position of the work implement 20 is indirectly detected. Further, a three-point link mechanism comprising a top link 27 and left and right lower links 28, 28 is provided at the rear part of the rear mission case 14, and the work machine 20 is configured to be connectable to the rear end part.
[0010]
The illustrated working machine 20 is a rotary working machine, and extracts the rotational power of the engine 11 of the tractor 10 from the PTO shaft 21 on the rear surface of the rear mission case 14 and transmits it to the working machine 20 side via the transmission shaft 29. The tillage shaft 31 having a plurality of tilling claws 33... Is rotated through the conduction mechanism on the working machine 20 side to plow the farm field.
[0011]
A brake device for braking the rear wheels 1 and 1 of the tractor 10 will be described with reference to FIG. The drive shaft 36 for driving the rear wheels 1 and 1 provided in the rear mission case 14 is provided with brake discs 37. The brake discs 37 are connected to the brake pedal 2 independently from each other via a link mechanism, and the discs are pressure-bonded to each other when the brake pedal 2 is depressed. Thereby, in the work in the field, the rear wheel of the tractor 10 can be braked only on one side, and the adjacent turning is facilitated. The rotational power of the engine 12 of the tractor 10 is transmitted to the main clutch 32, the forward / reverse switching device 34, the main transmission 33A, and the auxiliary transmission 33B, and the rotational power output by the auxiliary transmission 33B is transmitted to the rear wheels. Branching to the differential device 39 and the front wheel drive transmission device 60.
[0012]
The power steering device 5 of the tractor 10 will be described with reference to FIG. The power steering device 5 inputs a rotation operation of the steering handle 3 to the steering unit 41 via the steering shaft 40 and the like. The gerotor 42 is rotated according to the rotation of the steering shaft 40, and the hydraulic pressure of the pump 43 is output from the steering unit 41. In the oil path between the steering unit 41 and the front-wheel steering hydraulic cylinder 44, a switching control valve 47 having throttles 46, 46 for allowing a part of the pressure oil to escape to the tank 45, and delivery of the switching control valve 47 A check valve 48 for stopping the backflow of the pressurized oil is provided. The switching control valve 47 is normally positioned on the side of the oil chamber 49 having the throttles 46, 46, and is switched to the oil chamber 50 without the throttles 46, 46 according to a switching command from the controller 7. It is configured to send to. That is, when the switching control valve 47 is switched to the hydraulic chamber 50 where the throttles 46 and 46 are not provided, the steering amount of the front wheels 4 and 4 is increased relative to the operation amount of the steering handle 3 as compared with the normal time. Can do.
[0013]
As shown in FIG. 5, the controller 7 has a CPU for processing information of various sensors and switches, a RAM for temporarily storing this information, a ROM for setting this control program, and the like. . The input unit includes the control switch 8, the forward switch 16F, the reverse switch 16R, the front wheel turning angle sensor 9, the left and right brake switches 6 and 6, the potentiometer 18s of the shift lever 18, and the position lever 19 A potentiometer 19s, a PTO on / off switch 22, and a lift arm angle sensor 23 are connected to each other. Further, the output portion includes forward and backward solenoids 51F and 51R of the forward hydraulic clutches 52F and 52R, and a solenoid of the switching control valve 59 that opens the oil passage in a stepwise manner according to the PTO on / off switch 22. 59a and 59b, solenoids 66s and 67s of a proportional pressure control valve that expands and contracts the piston of the elevating cylinder 24, and a solenoid 47s of a switching control valve 47 that switches the amount of pressure oil to the steering cylinder 44 are connected to each other. Yes.
[0014]
For the action of the steering system of the configured tractor 10 as above will be described with reference to the flowchart of FIG.
[0015]
First, the power supply system of the tractor 10 is turned “ON” and the engine 12 is started (STEP 1), and the controller 7 reads the setting state and connection state of the switches such as the control switch 8 and sensors (STEP 2). Next, it is determined whether one of the left and right brake switches 6 is turned on (STEP 3). If “YES” is determined here, the lift arm angle sensor 23s subsequently determines whether or not the height of the work implement 20 is equal to or greater than a certain level, and subsequently determines whether the shift position is at the low speed side and the PTO ON / OFF switch 22 is ON. If all of these determinations (STEPs 4, 5, and 6) are YES, an energization command is output to the solenoid 47s of the switching control valve 47. The output is deenergized when the cutting angle of the front wheels 4 and 4 is returned to the substantially neutral position (STEP 9).
[0016]
As a result, the operator can cut the front wheels 4 and 4 with a small amount of steering handle operation by depressing the brake pedal 2 when approaching the end of the field and making a small turn at the time of work, so that labor saving can be achieved. it can. In addition, since the control for greatly steering the front wheels 4 and 4 at the time of turning is made possible by detecting the depression of the brake pedals 2 and 2, after the large turn without turning on the brake pedals 2 and 2, During the meandering, the tractor 10 can be driven by the same steering operation as in the normal state, so that a stable steering operation can be performed.
[0017]
As a means for detecting the position of the work implement 20 in STEP 4, the rotation angle of the position lever 19 is detected regardless of the lift arm angle, and the detected angle is detected to raise the work implement 20 to the non-work position. May be. Thus, if the raising operation of the lever 19 is detected and a switching command is output from the controller 7, the hydraulic operation delay of the elevating cylinder 24 can be eliminated and a quick control operation can be realized. be able to.
[0018]
The flowchart shown in FIG. 6 is a flowchart showing the present invention. In STEP 4, a condition for detecting the steering speed of the operator is added. That is, if the steering speed is detected from the turning angle per unit time from the front wheel turning angle sensor 9 of the tractor 10 and this speed is equal to or higher than the operation speed assumed to be a small turn, it is combined with the determination of other conditions. Thus, the steering amount of the front wheels 4, 4 is increased with respect to the operation amount of the steering handle 3.
[0019]
Further, in STEP 9, the state in which the steering amount is increased is configured to detect the “down” operation of the work machine 20 by the potentiometer 19 s of the position lever 19 and turn off the switching control valve 47. As a result, compared to the configuration in which the power is turned off when the front wheels 4 and 4 are neutrally restored, the tractor 10 is moved backward to the heel while the work implement 20 is raised after turning and is steered to the heel. The front wheels 4 and 4 can be steered with few steering operations.
[0020]
As a means for detecting this lowering operation, the angle of the lift arm 26 may be detected, and the work machine 20 continuously moves up and down between the lowered position and the raised position in the vicinity of the cockpit 17. A switch may be provided, and the “down” operation may be detected by this switch. Further, in place of the condition for increasing the operation amount of the front wheels 4 and 4 in STEP 4, it is possible to detect when the turning angle of the front wheels 4 and 4 has reached an angle (about 30 degrees) assumed to be a small turn. good.
[0021]
[0022]
[0023]
In addition, although the code | symbol of the member corresponding to the structure of embodiment is attached | subjected to a claim, this invention is not limited to this embodiment by this code | symbol.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a control operation during turning of a tractor.
FIG. 2 is an overall side view of the tractor.
FIG. 3 is a diagram showing power transmission of a tractor.
FIG. 4 is a partial hydraulic circuit diagram of the tractor.
FIG. 5 is a block diagram showing a connection state of a controller.
FIG. 6 is a flowchart showing the control operation of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Drive wheel 2 Brake pedal 3 Steering handle 4 Front wheel 5 Power steering device 6 Brake switch
19 Position lever
19s Potentiometer at position lever base
20 working machines
23 Lift arm
23s Lift arm angle sensor

Claims (1)

In a work vehicle having brake pedals 2 and 2 that brake the left and right drive wheels 1 and 1 independently, and a steering device 5 that can change the operation amount of the steering wheels 4 and 4 with respect to the operation amount of the steering handle 3. , A detecting means 6 for detecting the depression operation of the brake pedals 2 and 2 and a means 19s (23s) for detecting the height of the work implement 20 are provided, and the depression operation of the brake pedal 2 is detected and the work implement 20 sometimes height is constant over the with increases configured to be capable of steering amount of the steering wheel 4 and 4 with respect to the operation amount of the steering wheel 3, a state in which increasing the steering amount by the steering device 5 A steering device for a work vehicle, wherein the steering device is released in conjunction with a lowering operation of the work machine 20 .

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