JP2004001748A - Steering device of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the steering performance of a working vehicle by solving the difficulty in an accurate operation of the working vehicle such as an agricultural tractor having a steering device capable of changing the steering angle of a front wheel relating to the steering amount of a steering handle to reduce the steering operation at the time of ridge edge turning during cultivation work, but having problem of damaging operating performance because a vehicle body is steered by an large amount if not accurately operated when necessary. <P>SOLUTION: A tractor is provided with a front wheel steered angle sensor 9 for detecting a steering angle. When the detected value of the sensor 9 shows the angle supposed as turning, the steering amount of steering wheels 4 and 4 to the operating amount of a steering handle 3 is increased by a steering device 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD 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 Application Laid-Open No. 8-156812, in order to reduce the steering operation during pillow turning in a tilling operation, the turning of the front wheel with respect to the operation amount of a steering handle is reduced. A device provided with a steering device capable of changing an angle is known.
[0003]
[Problems to be solved by the invention]
However, since the operation disclosed in the above publication has a configuration in which the operation amount of the steering device is switched by a mode changeover switch, if the small-turn turning and the large-turn turning are repeatedly required depending on the shape of the field, the turning is performed. It is necessary to switch the mode changeover switch every time to increase the steering amount of the front wheels or to change the steering amount as usual. Therefore, the operability of the tractor has been impaired.
[0004]
[Means for Solving the Problems]
The present invention has taken the following technical measures in order to solve the above problems. That is, in a working vehicle having left and right drive wheels 1 and 1 and left and right steered wheels 4 and 4, and a steering device 5 capable of changing the amount of operation of the steered wheels 4 and 4 with respect to the amount of operation of the steering handle 3, The vehicle is provided with a sensor 9 for detecting a steering angle, and when the detection value of the sensor 9 detects an angle assumed to be turning, the steering device 5 controls the steering wheel 4, 4 is a steering apparatus for a working vehicle, wherein the steering amount is configured to be increased.
[0005]
【The invention's effect】
Thus, it is determined by the sensor 9 that detects the steering angle that the operator makes a small turn, and when the detection value of the sensor 9 detects the angle that is assumed to be a turn, the operation amount of the steering wheel 3 is determined. The steered angle of the steered wheels 4 and 4 can be increased, so that when the steering amount of the steered wheels 4 and 4 increases, such as when making a large turn or when the turning is completed, the normal steering operation can be performed. It becomes possible and the operability of the work vehicle is improved.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described for an agricultural tractor (hereinafter, tractor 10) as a work vehicle.
The overall configuration of the tractor 10 will be described. The tractor 10 is provided with an engine 12 inside a hood 11 at the front of the fuselage, 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. Front wheels 4, 4, which are steering wheels, are provided below and to the right and left of the engine 12, and rear wheels 1, 1, which are driving wheels, are provided on the left and right sides of the rear transmission case 13. The front wheels 1, 1 are provided with a front wheel turning angle sensor 9 for detecting the steering angle, and configured to detect the steering of the tractor 10.
[0007]
A handle post 15 is provided on a rear surface of the bonnet 11, a forward / reverse switching lever 16 is provided on a side of the handle post 15, and a steering handle 3 is provided to protrude above the post 15. The rotation of the steering handle 3 causes the front wheels 4, 4 to be steered via a power steering device 5, which is a steering device described later. A forward switch 16F that turns on when pushed forward and switches a switching control valve 51, which will be described later, and switches the control valve 51 when turned back when pulled backward, at the rotation base of the forward / reverse switching lever 16. A reverse switch 16R is provided. Brake pedals 2 and 2 for braking the right and left rear wheels 1 and 1 are provided below the handle post 15. Brake switches 6 and 6, which are means for detecting this stepping operation, are provided at the left and right turning bases of the brake pedals 2 and 2, respectively, and are turned on when the stepping is performed.
[0008]
Explaining the vicinity of the cockpit 17 of the tractor 10, a control switch 8 for turning on / off the control for changing the operation amount of the front wheels 4 and 4 at the time of turning; , A position lever 19 which is an operation unit of the working machine 20 is provided. Further, a PTO on / off switch 22 for turning on / off the rotation of a PTO shaft 21 for driving the work machine 20 described later is provided. A potentiometer 18 s is provided at the rotation base of the shift lever 18, and an operator's lever operation is input to the controller 7, which is a control unit provided below the cockpit 17, and the transmission cases 13 and 14 are operated in response to the shift operation. The configuration is such that the internal transmission 33 is switched. A potentiometer 19s is also provided at the rotation base of the position lever 19, and the controller 7 detects the operation angle of the lever 19, and the set angle of the lift arm angle sensor 23s described later coincides accordingly. The solenoids 66s and 67s of the 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 a rear upper portion of the rear transmission case 13. The cylinder case 25 has a built-in working machine elevating cylinder 24 built therein, and lift arms 26, 26 supported on the left and right sides of the case 25 are vertically rotated by the expansion and contraction of a piston of the elevating cylinder 24. A lift arm angle sensor 23s, which is a work implement position detecting means, is provided at the rotation base of the lift arm 26 to indirectly detect the elevation position of the work implement 20. Further, a three-point link mechanism including a top link 27 and left and right lower links 28, 28 is provided at a rear portion of the rear transmission case 14, and the working machine 20 can be connected to the rear end.
[0010]
The working machine 20 in the illustrated example is a rotary working machine, which takes out the rotational power of the engine 11 of the tractor 10 from the PTO shaft 21 on the rear surface of the rear transmission case 14 and transmits it to the working machine 20 via a transmission shaft 29. The tilling shaft 31 having a plurality of tilling claws 33... Is rotated via the transmission mechanism on the working machine 20 side to plow the field.
[0011]
A brake device for braking the rear wheels 1, 1 of the tractor 10 will be described with reference to FIG. A drive shaft 36 for driving the rear wheels 1, 1 provided inside the rear transmission case 14 is provided with brake disks 37,. The brake discs 37 are connected to the brake pedal 2 independently of the left and right via a link mechanism, and the discs are pressure-bonded by the depression operation of the brake pedal 2. As a result, in the work on the field, the rear wheel of the tractor 10 can be braked on only one side, and 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 from the auxiliary transmission 33B is transmitted to the rear wheels. It branches to a differential device 39 and a 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 a steering unit 41 via a steering shaft 40 or the like. The gerotor 42 is rotated in accordance with 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 passage 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 located 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 by a switching command from the controller 7, and the total flow rate is controlled by the cylinder 44. It is configured to be sent to That is, when the switching control valve 47 is switched to the hydraulic chamber 50 in which the throttles 46 and 46 are not provided, the steering amount of the front wheels 4 and 4 is increased with respect to the operation amount of the steering handle 3 as compared with the normal state. Can be.
[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 section 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, 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. The output unit includes solenoids 51F and 51R for moving forward and backward hydraulic clutches 52F and 52R, and a solenoid for a 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 proportional pressure control valves for extending and retracting the piston of the elevating cylinder 24, and solenoids 47s of a switching control valve 47 for switching the amount of pressurized oil to the steering cylinder 44 are connected and provided. I have.
[0014]
The operation of the steering device of the tractor 10 configured as described 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 the sensors (STEP 2). Next, it is determined whether one of the left and right brake switches 6 is turned on (STEP 3). If YES here, the lift arm angle sensor 23s then determines whether the height of the work implement 20 is equal to or greater than a predetermined value, and then determines whether the shift position is on 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. This output is stopped when the turning angles of the front wheels 4 and 4 are returned to the substantially neutral position (STEP 9).
[0016]
This allows the operator to turn the front wheels 4 and 4 largely with a small steering wheel operation amount by depressing the brake pedal 2 when making a small turn and approaching the field edge during work, so that labor can be saved. it can. In addition, since the control for largely steering the front wheels 4 and 4 at the time of this turning is made to be operable by detecting the depression of the brake pedals 2 and 2, it is possible to perform a large turning without turning on the brake pedals 2 and after the turning. When the tractor 10 is meandering, the tractor 10 can travel by the same steering operation as in the normal state, so that a stable steering operation can be performed.
[0017]
As means for detecting the position of the work machine 20 in STEP 4, the rotation angle of the position lever 19 is detected regardless of the lift arm angle, and this detection angle detects that the work machine 20 has been raised to the non-work position. May be. By detecting the raising operation of the lever 19 and outputting the switching command from the controller 7, it is possible to eliminate the hydraulic operation delay of the elevating cylinder 24, thereby enabling quick control operation. be able to.
[0018]
The flowchart shown in FIG. 6 is another embodiment of the present invention, in which a condition for detecting the steering speed of the operator is added in STEP4. That is, the steering speed is detected from the turning angle per unit time by the front wheel turning angle sensor 9 of the tractor 10, and if this speed is equal to or higher than the operating speed that is assumed to be a small turning, it is combined with the determination of other conditions. Thus, the steering amount of the front wheels 4 and 4 is increased with respect to the operation amount of the steering handle 3.
[0019]
In STEP 9, the state in which the steering amount is increased is detected by the potentiometer 19s of the position lever 19 detecting the "down" operation of the work implement 20, and the energization of the switching control valve 47 is turned off. As a result, compared to the configuration in which the power is turned off when the front wheels 4 and 4 return to neutral as described above, the tractor 10 can be moved backward to the ridge with the work machine 20 raised after turning and even steered to this ridge. Of the front wheels 4 and 4 can be steered by a small steering operation.
[0020]
As means for detecting this lowering operation, the angle of the lift arm 26 may be detected, or the work implement 20 may be continuously raised and lowered between the lowered position and the raised position near the cockpit 17. A switch may be provided, and the "down" operation may be detected by the switch. Further, as a condition for increasing the actuation amount of the front wheels 4 and 4 in STEP 4, a configuration may be adopted in which a time when the turning angle of the front wheels 4 and 4 reaches an angle (about 30 degrees) assumed to be a small turning is reached.
[0021]
In the claims, the reference numerals of the members corresponding to the configuration of the embodiment are attached, but the reference numerals do not limit the present invention to the embodiment.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a control operation at the time of turning of a tractor.
FIG. 2 is an overall side view of the tractor.
FIG. 3 is a view 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 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 9 Front wheel angle sensor

Claims (1)

A working vehicle comprising left and right drive wheels 1, 1 and left and right steered wheels 4, 4 and a steering device 5 capable of changing the amount of operation of the steered wheels 4, 4 with respect to the amount of operation of the steering handle 3. Is provided with a sensor 9 for detecting a steering angle, and when the detected value of the sensor 9 detects an angle assumed to be turning, the steering device 5 controls the steering wheels 4, 4 with respect to the operation amount of the steering handle 3. A steering device for a work vehicle, wherein the steering amount is configured to be increased.

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