JP3692679B2 - Turning control device for work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a configuration of a control device during turning of a work vehicle for agriculture, construction, or transportation.
[0002]
[Prior art and problems]
2. Description of the Related Art Conventionally, there has been a work vehicle that transmits a steering operation of an operator to a steering wheel via a power steering device and has steering amount change means that can change the steering amount of the steering wheel. For example, the agricultural tractor disclosed in Japanese Patent Application Laid-Open No. 7-323848 is provided with a transmission gear that changes the rotational speed of the shaft in the middle of the steering shaft that is input to the power steering device, and the transmission gear is switched by an operation lever. It has become. As a result, during work, the front gear can be greatly steered with a small steering handle operation by switching the transmission gear, thereby saving work.
[0003]
However, since the front wheels are always steered with a small amount of steering operation when performing farm work with the tractor, the tractor can be operated even if the steering operation is moderately performed at the time of finishing the turning or turning with a large turning radius. However, there was a problem that it was difficult to steer.
[0004]
[Means for Solving the Problems]
The present invention has taken the following measures for the above problems. That is, according to the first aspect of the present invention, in the work vehicle having the steering amount changing means 3 capable of changing the steering amount of the steering wheel 2 with respect to the steering operation amount of the operator, the steering operation of the operator or the steering wheel is provided. Control unit 20 for determining the steering amount and steering speed based on the steering operation of No. 2, switching means 3 L (3R) for switching the operating state of the steering amount changing means 3, and detecting whether or not the vehicle is in a high-speed traveling state When the sensor 28 detects that the vehicle is not in a high speed running state, and the control unit 20 determines that the steering amount and the steering speed exceed predetermined values, the switching means 3L ( 3R) to increase the steering amount of the steering wheel 2 with respect to the operation amount of the operator .
According to the second aspect of the present invention, when the vehicle turns, the hydraulic cylinder 40 that raises the work machine 22 connected to the vehicle body, and the steering amount changing means that can change the steering amount of the steering wheel 2 relative to the steering operation amount of the operator. In the work vehicle having 3, the control unit 20 for determining the steering amount and the steering speed based on the steering operation of the operator or the steering operation of the steering wheel 2 and the operating state of the steering amount changing means 3 are switched. A switching means 3L (3R) and a sensor 28 for detecting whether or not the vehicle is in a high speed running state are provided. The sensor 28 detects that the vehicle is not in a high speed running state, and the control unit 20 determines the steering amount. When it is determined that the amount is equal to or greater than the fixed amount, the work unit 22 is lifted by driving the cylinder 40, and it is further determined that the work unit 22 is further lifted and the steering speed exceeds a predetermined speed. Increasing the steering amount of the steering wheel 2 with respect to the switching means 3L (3R) by the operation amount of the operator to have the turn control system for a working vehicle according to claim.
[0005]
[Operation and effect of the invention]
The turning control device for a work vehicle according to claim 1 and claim 2 configured as described above discriminates a large turning and a small turning even during a turn based on a steering speed , and the steering operation speed is a predetermined speed. when exceeding, i.e. maneuverability during turning only, and changes the more the operating state of the steering amount changing means 3 to the switching means 3L (3R) increasing the steering amount of the steering wheel 2 for steering operation amount of the operator. As a result, it is not necessary to switch the steering amount changing means of the operator himself / herself every time the work vehicle requires a small turn or a large turn or when the traveling direction of the work vehicle is adjusted at the end of the turn. The operability can be improved and the working time can be shortened.
Further, in the turning control device for the work vehicle according to the second aspect, since the steering amount of the steered wheel 2 is increased under the condition that the work machine 22 is raised, a ground work machine such as the rotary work machine 22 is installed on the work vehicle. When they are connected, they do not make a small turn while in the landing state, and the operability of the vehicle is not impaired.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described with respect to an agricultural tractor (hereinafter referred to as tractor 10) which is a work vehicle.
The tractor 10 is provided with an engine 12 inside the bonnet 11, and a clutch housing, a transmission case 13, and a rear transmission case 14 are integrally connected from the engine 12 to constitute a main frame. Further, front wheels 2 and 2 which are steered wheels are provided on the front left and right of the vehicle body, and rear wheels 16 and 16 are provided on the left and right of the rear. Alternatively, it is configured to transmit to the front and rear wheels 2, 2, 16, 16.
[0007]
A steering post 17 is provided behind the engine 12, and a steering handle 18 is provided so as to protrude therefrom. And it is the structure which steers the front wheels 2 and 2 via the power steering apparatus 1 mentioned later by rotation operation of the steering handle 18. Further, the front wheels 2 and 2 are provided with a front wheel turning angle sensor 4 to detect the steering amount of the operator as an angle, and the controller 20 which is a control unit described later detects a steering angle per unit time. The steering operation speed is calculated.
[0008]
A control seat 21 is provided behind the steering handle 18, and a position lever 23 for changing the raising / lowering position of the work implement 22 and a shift lever 24 for switching the transmission device are provided protruding from the side of the control seat 21. Yes. A potentiometer 25 that detects the operation position of the operator is provided at the rotation base of the position lever 23, and the lift arms 42 and 42 are rotated in accordance with the operation angle of the lever 23 to raise and lower the work machine 22. ing. Further, a high speed position detection switch 28 that is turned “ON” when the speed change lever 24 is operated to a high speed position is provided at the rotation base of the speed change lever 24.
[0009]
Further, a control switch 26 for turning on / off the operation of the turning control device of the present invention is provided on the side of the cockpit 21, and the rear mission case 14 below the cockpit 21 is tilted in the front / rear / right / left directions of the vehicle body. A slope sensor 27 is provided as an inclination detecting means for detecting. The sensors 25 and the switches 26 and 28 are connected to a controller 20 provided below the cockpit 21.
[0010]
The rear part of the tractor 10 will be described. A cylinder case 41 containing a working machine lifting / lowering cylinder 40 is provided at the rear upper part of the rear mission case 14, and lift arms 42, 42 provided on both sides of the case 41 by expanding and contracting the piston of the cylinder 40. It is configured to rotate up and down. In addition, a three-point link mechanism including a top link 43 and left and right lower links 44, 44 is provided at the rear part of the rear mission case 14, and the work machine 22 is connected to this.
[0011]
The working machine 22 shown in the figure is a rotary working machine, and transmits power to the working machine 22 side from a PTO shaft 45 projecting from the rear surface of the tractor 10 via a universal joint 46, and has a tilling shaft 48 having tilling claws 47. It is the structure which plows a farm field by rotating.
The power steering device 1 includes a power steering cylinder 32 that steers the front wheels 2 and 2 and a hydraulic circuit that drives the cylinder. More specifically, the rotation operation of the steering handle 18 is input to the steering unit 30 via the steering shaft 19. Then, according to the rotation of the steering shaft 19, the oil pressure of the pump 31 is input to the steering unit 30 via the diversion valve 9, and the oil pressure of the pump 31 is transmitted to the power steering cylinder 32. . The piston tip of the power steering cylinder 32 is connected to the knuckle arm 33 of the right front wheel 2, and the knuckle arm 33 and the knuckle arm 34 of the left front wheel 2 are connected by a tie rod 35 to connect the left and right front wheels 2. 2 is steered. The circuit branched by the diversion valve 9 is connected to a switching control valve 3 which is a steering amount changing means, and an output side circuit of the switching control valve 3 is connected between the steering unit 31 and the power steering cylinder 32. Connected to the hydraulic circuit between. When the solenoid 3L of the switching control valve 3 is energized, it switches to the hydraulic chamber 36L and the cutting angle of the front wheels 2 and 2 is cut to the left, and when the coil 3R of the switching control valve 3 is energized, the front wheel 2 is switched to the hydraulic chamber 36R. The angle of 2 is cut to the right.
[0012]
As described above, the pressure oil discharged from the pump 31 is branched by the diverter valve 9 and provided in parallel to the steering unit 30 and the switching control valve 3 so as to be able to flow into the power steering cylinder 32. The steering operation is always transmitted to the power steering cylinder 32, and when the switching control valve 3 is switched, the steering amount of the front wheels 2 and 2 is steered so as to be increased with respect to the operation amount of the operator. ing.
[0013]
The controller 20 includes a CPU that processes signals from various sensors and switches, a RAM that temporarily stores the signals, a ROM that stores a control program for the turning control device of the present invention, and the like. The control switch 26, the front wheel turning angle sensor 4, the potentiometer 25, the high-speed position detection switch 28, and the slope sensor 27 are connected. Further, solenoids 50 and 51 of switching control valves for raising and lowering the lift arms 42 and 42 and solenoids 3L and 3R of the switching control valve 3 for sending the oil amount to the power steering cylinder 32 are connected to the output unit. .
[0014]
Next, the operation of the turning control device of the present invention will be described based on the flowcharts of FIGS.
First, the operable conditions of the turning control device will be described with reference to FIG. When the power supply system of the tractor 10 is set to “ON”, the controller 20 reads connection states and setting states of various sensors and switches (STEP 1). Then, it is determined whether the control switch 26 is “ON” (STEP 2), then it is determined whether the high-speed position detection switch 28 is “OFF” (STEP 3), and the detection angle of the slope sensor 27 is constant. It is determined whether the inclination angle is equal to or less than the above inclination angle (STEP 4), and when all these determinations are YES, the turning control device can be operated. Thereby, the operation of the turning control is performed in a high-speed traveling state or a steep slope so that the tractor 10 does not fall down.
[0015]
In addition, as another form of the speed detection switch 28 in STEP3, it is good also as a structure which detects a high-speed driving | running state by rotation of a Doppler type ground sensor or the drive shaft of a wheel. As a result, it is possible to detect a state in which the shift position is at a low speed and the vehicle is traveling at a high speed due to a descending slope or an increase in the engine speed.
Next, the operation of the turning control device will be described with reference to FIG.
[0016]
First, in STEP 1, it is determined whether or not the steering direction of the front wheels 2 and 2 is equal to or greater than a certain angle, that is, whether or not the tractor 10 has entered a turning state. If “YES” here, the process proceeds to STEP 2, energization output is performed to the solenoid 50 of the switching control valve, and the work implement 22 is raised. At the same time, the steering speed of the front wheels 2 and 2 is calculated, and it is determined whether this speed is equal to or higher than a set speed assumed to be a small turn, that is, a sudden turn (STEP 3). If YES here, the oil chamber 36R or the oil chamber is energized so that the solenoid 3R or the solenoid 3L of the switching control valve 3 is energized to further cut the front wheels 2 and 2 being steered in the same direction. Switch to 36L.
[0017]
At this time, the correspondence relationship between the turning angle (θw) of the front wheels 2 and 2 and the operation angle (θs) of the steering wheel 18 is set as shown in the graph (solid line) of FIG. 6, for example. Here, the steering speed is calculated up to the front wheel break angle corresponding to one rotation (angle 2π) of the steering handle 18, and when a detection result exceeding the predetermined speed is detected during this time, the steering handle 18 is operated thereafter. Is configured to steer the front wheels 2 and 2 to the locked position at about 1.5 rotations (angle 3π). As a result, the front wheels 2 and 2 can be largely cut with less steering operation than during normal steering operation (one-dot chain line), so that the steering operation time and the amount of operation during turning are reduced. In addition, even when working in a field that requires a small turn and a large turn at random, the turning control device operates only during a small turn, so the front wheels 2 and 2 are steered excessively when not required. The operability of 10 is not impaired.
[0018]
Further, the state in which the turning angle of the front wheels 2 and 2 has increased in STEP 4 is when the steering wheel 18 is returned to the straight traveling state after turning and when the front wheel turning angle sensor 4 detects the return to the neutral range (in FIG. (Position corresponding to 2π) The energization of the solenoid 3L (3R) serving as the switching means of the switching control valve 3 is stopped, and the normal power steering operation state is restored.
[0019]
When detecting the operation speed of the operator, a steering angle sensor is provided on the rotating shaft 19 of the steering handle 18 so that the operation angle is detected and the operation speed is calculated by the controller. Further, a proportional pressure control valve or a variable orifice may be provided in place of the switching control valve 3, and the turning angle of the front wheels 2 and 2 during turning may be increased steplessly as shown in the graph of FIG. As a result, the operability of the tractor 10 can be improved by reducing the impact when the switching control valve 3 is switched and the front wheels 2 and 2 are suddenly turned off, and the uncomfortable feeling during operation.
[0020]
Further, instead of the steering amount changing means using the hydraulic mechanism such as the switching control valve 3 as described above, a gear type steering amount changing means as shown in FIG. 8 may be used. Here, a synchromesh gear type transmission 3 'for changing the rotational speed of the coaxial 19 is provided between the steering shaft 19 and the steering unit 30, and a synchromesh clutch 56 having a high speed gear 54 and a low speed gear 55 is used as a switching means. The electric motor 5 ′ is slid in the direction of the same axis 16 to change the rotation of the steering shaft 19 and input it to the steering unit 30. That is, during normal steering, the synchro clutch 56 is slid downward in the figure, and the rotation of the steering shaft 19 is transmitted to the gear set 54 -input shaft 57 and input to the steering unit 30. Further, when the controller 20 detects an operation speed that is equal to or higher than a predetermined speed assumed to be a sudden turn, the synchro clutch 56 is slid upward in the figure to rotate the steering shaft 19 so that the gear set 55-speed increasing shaft 58 is rotated. -It transmits with the input shaft 57, and inputs into the steering unit 30.
[0021]
As a result, when turning slightly, the front wheels 2 and 2 can be largely turned with less steering operation than during normal steering operation, thereby reducing the operation time and the operation amount. In addition, even when working in a field that requires small turning and large turning at random, the turning control device operates only during small turning, so the front wheels 2 and 2 are steered excessively when not required. The operability of 10 is not impaired. In addition, the gear-type turning control device can be configured with a compact component installation space, and the production cost can be reduced by reducing the number of components, as compared with a configuration using a hydraulic mechanism.
[0022]
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 hydraulic circuit diagram of a power steering.
FIG. 2 is a flowchart showing a power steering operable state.
FIG. 3 is a flowchart showing the operation of power steering.
FIG. 4 is a block diagram showing connection of a controller.
FIG. 5 is an overall side view of the tractor.
FIG. 6 is a diagram showing a relationship between a steering operation angle and a front wheel turning angle according to the present invention.
FIG. 7 is a diagram showing a relationship between a steering operation angle and a front wheel turning angle when a switching unit is configured in a stepless manner.
FIG. 8 is a block diagram showing connection of a controller when the operation ratio changing means is configured as a gear type and is switched by an electric motor.
[Explanation of symbols]
1 Power steering device 2 Front wheel 3 Switching control valve 4 Front wheel turning angle sensor

Claims (2)

In working vehicle having an operator's steering operation quantity steering amount changing means 3 capable of changing the steering amount of the steering wheel 2 with respect to, steering operation, or the steering amount based on the steering operation of the steering wheel 2 of the operator and a control unit 20 determines steering speed, the switching means 3 L (3R) for switching the operating state of the steering amount changing means 3, the sensor 28 that the vehicle detects whether high-speed running state is provided, the sensor 28 When the state where the vehicle is not in the high speed running state is detected by the control unit 20 and the steering amount and the steering speed are determined to exceed predetermined values by the control unit 20 , the switching means 3L (3R) controls the operation amount for the operator. A turning control device for a work vehicle, characterized in that the steering amount of the steering wheel 2 is increased.   In a work vehicle having a hydraulic cylinder 40 that raises the work machine 22 connected to the vehicle body when turning the vehicle, and a steering amount changing means 3 that can change the steering amount of the steering wheel 2 with respect to the steering operation amount of the operator, A control unit 20 for determining a steering amount and a steering speed based on a steering operation of the operator or a steering operation of the steering wheel 2; a switching unit 3L (3R) for switching an operating state of the steering amount changing unit 3; A sensor 28 is provided for detecting whether or not the vehicle is in a high speed running state. The sensor 28 detects that the vehicle is not in a high speed running state, and the control unit 20 determines that the steering amount has reached a predetermined amount or more. When the cylinder 40 is driven to raise the work machine 22 and the work machine 22 is further driven to rise and the steering speed exceeds a predetermined speed, the switching means 3L (3 ) The turn control system for a working vehicle, characterized by increasing the steering amount of the steering wheel 2 with respect to the operation amount of the operator.

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