JPH10236331A - Steering device of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the steering performance of a working vehicle by detecting the actuating operation of a brake pedal, and increasing the steering amount of a steering wheel to the operating amount of a steering handle by a steering device when the actuating operation is detected. SOLUTION: A brake pedal 2 for braking right and left rear wheels is provided below a handle post 15, and a brake switch 6 which is a means for detecting the actuating operation is provided on the right and left turning base parts of the brake pedal 2. When the actuating operation of the brake pedal 2 is detected by these brake switches 6, the steering amount of a steering wheel 4 to the operation amount of a steering handle 3 can be increased by the steering device. Thus, when the increase in the steering amount of the steering wheel 4 in large turning or after the end of turning is inconvenient, ordinary steering operation is enabled so as to improve the operability of a working vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a tractor or rice transplanter working vehicle.

[0002]

2. Description of the Related Art Conventionally, a working vehicle is provided with a steering wheel, such as a tractor disclosed in Japanese Patent Application Laid-Open No. 8-156812, in order to reduce a steering operation during a pillow turn in a tilling operation. There is known a steering device provided with a steering device capable of changing a turning angle of a front wheel with respect to the operation amount of the vehicle.

[0003]

However, the one disclosed in the above publication has a configuration in which the operation amount of the steering device is switched by a mode changeover switch, so that a small turning and a large turning can be performed depending on the shape of the field. If it is required repeatedly, it is necessary to switch the mode changeover switch every time the vehicle turns, to switch between increasing the steering amount of the front wheels or setting the steering amount as usual. For this reason, the operability of the tractor has been impaired.

[0004]

The present invention employs the following technical means in order to solve the above problems. That is, a work having brake pedals 2 and 2 for independently braking the left and right drive wheels 1 and 1 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. In the vehicle, a detecting means 6 for detecting a depression operation of the brake pedals 2, 2 is provided,
A steering device for a work vehicle, wherein when the depression operation of the brake pedal 2 is detected, the steering device 5 can increase the steering amount of the steered wheels 4 and 4 with respect to the operation amount of the steering handle 3.

[0005]

According to the present invention, it is determined that the operator makes a small turn by depressing the brake pedals 2 and 2, and only when this depressing operation is detected, the steering amount with respect to the operation amount of the steering wheel 3 is steered. The turning angle of the 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 after finishing the turn, normal steering operation can be performed. The operability of the work vehicle is improved.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to an agricultural tractor (hereinafter, tractor 10) as a working vehicle. 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 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 steered wheels, are provided below and to the left and right 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.

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 handle post 15, and a steering handle 3 is provided to protrude above the post 15. The front wheels 4 and 4 are steered by a rotation operation of the steering handle 3 via a power steering device 5 which is a steering device described later. The turning base of the forward / reverse switching lever 16 is provided with a forward switch 16F that is turned on when pushed forward to switch a switching control valve 51 described later, and is switched on when pulled backward to switch the control valve 51. 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 pedal 2,2
Brake switches 6 and 6, which are means for detecting this stepping operation, are provided on the left and right turning bases, respectively, and are turned on when the stepping is performed.

The vicinity of the cockpit 17 of the tractor 10 will be described. A control switch 8 for turning on / off the control for changing the amount of operation of the front wheels 4 and 4 during turning is provided on the side of the cockpit 17. A lever 18 and a position lever 19 which is an operation unit of the work machine 20 are provided. In addition, a PTO on / off switch 22 for turning on / 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 shift lever 18.
The operation of the lever is input to the controller 7 which is a control unit provided below the cockpit 17, and the transmission 33 in the transmission cases 13 and 14 is switched according to the shift operation. A potentiometer 19 is also provided at the rotation base of the position lever 19.
The controller 7 detects the operation angle of the lever 19, and accordingly, the solenoid 66s of the proportional pressure control valve for lifting and lowering the work implement, so that the setting angle of the lift arm angle sensor 23s described later matches in accordance with the operation angle. The structure is such that the cylinder 24 described later is driven by exciting 67 s.

The structure 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. This cylinder case 2
5 has a built-in work machine elevating cylinder 24, and lift arms 26, 26 supported on the left and right sides of a case 25 are vertically rotated by the expansion and contraction of a piston of the elevating cylinder 24. The lift base 26 of the lift arm 26 has a lift arm angle sensor 2 as work implement position detecting means.
3 s is provided to indirectly detect the vertical position of the work machine 20. A top link 27 and left and right lower links 28, 28 are provided at the rear of the rear transmission case 14.
A three-point link mechanism is provided, and the work machine 20 can be connected to the rear end.

A working machine 20 in the illustrated example is a rotary working machine, which takes out the rotational power of an engine 11 of a tractor 10 from a PTO shaft 21 on the rear surface of a rear transmission case 14.
The power is transmitted to the work machine 20 via the transmission shaft 29, and the cultivation shaft 31 having a plurality of cultivating claws 33 is rotated via the transmission mechanism on the work machine 20 to plow the field. .

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 has brake discs 37 on the left and right sides, respectively.
Is provided. 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 pressed against each other by depressing 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, so that adjacent turning is facilitated. The tractor 10
The rotational power of the engine 12 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 wheel differential device 39. , To the front wheel drive transmission device 60.

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 hydraulic cylinder 44 for steering the front wheels, throttles 46 and 4 for releasing a part of the pressure oil to the tank 45 are provided.
6 and a check valve 48 for stopping the reverse flow of the pressure oil sent from the switching control valve 47. The switching control valve 47 normally operates the throttle 46,
It is located on the side of the oil chamber 49 having 46, and is switched to an oil chamber 50 not provided with the throttles 46, 46 by a switching command from the controller 7, and the entire flow rate is sent to the cylinder 44. That is, the switching control valve 47 sets the throttles 46, 46
When it is switched to the hydraulic chamber 50 without the
The steering amount of the front wheels 4 and 4 can be increased with respect to the operation amount of the steering handle 3 as compared with the normal state.

The controller 7 includes, as shown in FIG. 5, a CPU for processing information of various sensors and switches,
The configuration includes 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 angle sensor 9, the left and right brake switches 6, 6, and the speed change lever 18.
, A potentiometer 19s of the position lever 19, and a PTO on / off switch 22.
And the lift arm angle sensor 23 are connected to each other. The output unit includes a forward hydraulic clutch 52F, 5F.
2R forward and reverse solenoids 51F, 51R
And solenoids 59a and 5 of a switching control valve 59 for gradually opening an oil passage according to the PTO on / off switch 22.
9b, solenoids 66s and 67s of proportional pressure control valves for extending and retracting the piston of the lifting cylinder 24 are connected to solenoids 47s of a switching control valve 47 for switching the amount of pressurized oil to the steering cylinder 44.

The operation of the steering apparatus for the tractor 10 constructed as described above will be described with reference to the flowchart of FIG.

First, the power system of the tractor 10 is turned on.
And the engine 12 is started (STEP 1).
The controller 7 reads the setting state and connection state of switches and sensors such as the control switch 8 (STEP 7).
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 determines whether the height of the work implement 20 is equal to or greater than a predetermined value. Are determined, and these determinations (STEP
If all of 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).

With this, the operator can reach the edge of the field at the time of work and turn the brake pedal 2 when making a small turn.
By stepping down, the front wheels 4, 4 can be largely turned with a small steering wheel operation amount, so that labor can be saved. Also, during this turn, the front wheels 4, 4
The large steering is controlled by detecting the depression of the brake pedals 2 and 2 so that the control can be operated. Since the tractor 10 can be driven by the same steering operation as that described above, a stable steering operation can be performed.

As means for detecting the position of the work machine 20 in STEP 4, the rotation angle of the position lever 19 is detected irrespective of the lift arm angle, and the detected angle is used as the work machine 2
It may be detected that 0 has been raised to the non-working position.
By detecting the raising operation of the lever 19 and outputting the switching command from the controller 7, the delay in hydraulic operation of the lifting cylinder 24 can be eliminated, and a quick control operation can be performed. be able to.

The flowchart shown in FIG.
In another embodiment of the present invention, a condition for detecting the steering speed of the operator is added in STEP4. That is, the steering speed per unit time is detected by the front wheel turning angle sensor 9 of the tractor 10, and if this speed is equal to or higher than the operation speed assumed to be a small turn, the steering wheel is determined in accordance with other conditions. The steering amount of the front wheels 4 and 4 is increased with respect to the operation amount of 3.

In STEP 9, the operation of increasing the steering amount is detected by the potentiometer 19s of the position lever 19 detecting the "down" operation of the work machine 20, and the switching control valve 47 is turned off. As a result, as compared with the configuration in which the energization 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 steered to the ridge. Of the front wheels 4 and 4 can be steered by a small steering operation.

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 connected between the lowering position and the raising position near the cockpit 17. A switch for raising and lowering may be provided, and this switch may be used to detect a “down” operation. Also, STEP
4, instead of increasing the operation amount of the front wheels 4, 4, an angle (about 3
0 degree) may be detected.

Incidentally, the hydraulic clutches 52F, 52R and the PTO shaft 21 of the wet-type multi-plate type of the forward / reverse switching device 51 are provided.
Conventionally, the hydraulic clutch 54 of the same type for turning on and off the rotation of the motor requires a shock reduction device such as a booster valve and an accumulator in order to suppress a connection shock at the time of boosting. Therefore, if the hydraulic clutches 52 are provided in a large number, the number of the accumulators increases and the installation space is required, and the cost is high. Accordingly, here, among the plurality of hydraulic clutches, an oil passage communicating from the switching control valve 51 of the forward / reverse switching device 51 to the forward hydraulic clutch 52F, and an oil passage communicating from the control valve 51 to the reverse hydraulic clutch 52R. And a high-pressure hose 55 which is an elastic member.
5 is provided with a check valve 58 for urging a check ball 57 with springs 56 from both sides.

As described above, since the hydraulic clutches 52... Oil passages are connected to each other, it is possible to reduce the cost compared to providing a shock absorbing device such as an accumulator for each clutch. In addition, since the forward hydraulic clutch 52F and the reverse hydraulic clutch 52R of the forward / reverse switching device 51 are connected, when one of the pressures is increased, the pressure of the other clutch becomes 0 and the influence of the back pressure of each other can be eliminated. it can.

In the claims, the reference numerals of the members corresponding to the configuration of the embodiment are attached, but the present invention is not limited to the embodiment by the reference numerals.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a control operation at the time of turning 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 of another embodiment 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

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Yoshitaka Tani 1st person, Yachikura, Tobe-cho, Toyo-cho, Iyo-gun, Ehime Prefecture, Iseki Agricultural Machinery Co., Ltd. Nobuo (72) Inventor Nobuo Fujita No. 1 Hachikura, Tobe-cho, Iyo-gun, Ehime Prefecture Iseki Agricultural Machinery Co., Ltd.

Claims (1)

[Claims] 1. A brake pedal (2) for independently braking left and right drive wheels (1) and 1, a steering device (5) capable of changing an operation amount of steering wheels (4) with respect to an operation amount of a steering handle (3). In the working vehicle having the above, a detecting means 6 for detecting the depression operation of the brake pedals 2 and 2 is provided, and when the depression operation of the brake pedal 2 is detected, the steering device 5 controls the operation amount of the steering handle 3. A steering device for a work vehicle, wherein the steering amount of the steered wheels 4 and 4 is configured to be increased.