JP2003246275A - Wheel steering unit for towing type working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel steering unit for a towing type working machine in which a wheel steering angle of the machine is automatically operated so as to cancel the yawing of the machine when the machine is offset-towed by a tractor. <P>SOLUTION: When variable hitch angle towing is performed, a computer (11) of the wheel steering unit controls a draw bar sensor (5) for detecting a draw bar angle (θB) between a wheel axle and a hitch (4) of the tractor (1), a hitch sensor (6) for detecting a actual hitch angle (θA') between the hitch and the axle (7) of the working machine (2), and a steering mechanism (10) for calculating a hitch angle (θA) in calculation considering the offset and a deviated angle (θC) of the advancing direction of the tractor and the machine based on signals of a wheel sensor (9) for detecting the actual steering angle (θE) of the wheel (8) to set a target steering angle (θD) of the wheel (8) to bring the angle (θE) into coincidence with the target angle (θD). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel steering system for a working machine towed by a tractor, and more particularly,
The present invention relates to a wheel steering device suitable when a tractor offset-pulls a work implement.

[0002]

2. Description of the Related Art As a conventional wheel steering system for a towing type working machine, there are a steering mechanism for operating the wheels of the working machine, a computer for controlling the steering mechanism, a wheel axle of a tractor or a crossing angle between a drawbar and a hitch. A drawbar sensor for detecting a drawbar angle, a hitch sensor for detecting an actual hitch angle which is a crossing angle between a hitch and a wheel axle of a working machine, and a wheel sensor for detecting an actual steering angle of a wheel of a working machine,
The detection signals of the drawbar sensor and the hitch sensor are input to the computer, the deviation angle of the traveling direction of the working machine with respect to the traveling direction of the tractor is calculated, and the target steering angle of the wheel is set from that deviation angle, and the actual steering wheel of the working machine wheel is set. The one in which the computer controls the steering mechanism so that the angle becomes the target steering angle is disclosed in Japanese Patent Laid-Open No. 2001-301636.

Since the wheel steering system of the towed work machine does not control the steering angle of the work machine wheel in consideration of the effect of yawing due to the offset towing, when the offset amount between the tractor and the towed work machine becomes large, Depending on the situation, there was a problem that the tractor could not pull the work implement to go straight.

For example, when the tractor travels straight by offset-pulling the working machine at a variable hitch angle, the vehicle moves as shown in FIG.
As shown in (a), the center of gravity G of the working machine 2 is located at a position separated from the traction axis L of the tractor 1 by an offset amount H, but when the traveling is started, yawing that causes the working machine to swing around occurs, and the road surface If it is smooth, as shown in FIG. 4B, the working machine 2 finally moves to a position where the center of gravity G coincides with the traction axis L of the tractor 1. Actually, since there is a frictional resistance between the road surface and the work machine wheel, the state shown in FIG. 4 (b) is unlikely to occur, but depending on the road surface condition, for example, the road surface is a damp surface with a small frictional resistance, In the case of an inclined surface or the like, yawing appears remarkably. Although not shown, the same applies when pulling at a fixed hitch angle.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its object is to automatically cancel the yawing that occurs in a work machine in an offset towing state. Another object of the present invention is to provide a wheel steering device for a towing type work machine, which is capable of always advancing the towing type work machine according to a tractor by controlling the wheel steering angle of the working machine.

[0006]

In order to achieve the above object, the means adopted by the present invention are a steering mechanism for operating the wheels of a working machine, a computer for controlling the steering mechanism,
A drawbar sensor that detects the drawbar angle that is the intersection angle between the tractor wheel axle or drawbar and the hitch, a hitch sensor that detects the actual hitch angle that is the intersection angle between the hitch and the work equipment wheel axle, and the actual wheel of the work equipment. In a wheel steering system for a working machine towed by a variable hitch angle equipped with a wheel sensor that detects the steering angle, the detection signals of the drawbar sensor and the hitch sensor are input to a computer to consider the offset amount between the tractor and the working machine. The calculated hitch angle and the deviation angle between the advancing direction of the work implement and the advancing direction of the tractor are calculated, and the target steering angle of the wheels is set from the deviation angle. The computer controls the steering mechanism so that

A steering mechanism for operating the wheels of the working machine,
A fixed hitch equipped with a computer that controls the steering mechanism, a drawbar sensor that detects a drawbar angle that is a crossing angle between a wheel axle of a tractor or a drawbar and a hitch, and a wheel sensor that detects an actual steering angle of a work machine wheel. In a wheel steering system for a work machine that is towed by a corner, the detection signal of a drawbar sensor is input to a computer to calculate the deviation angle of the traveling direction of the work machine with respect to the traveling direction of the tractor, and the target wheel steering angle is calculated from that deviation angle. It is also a means of the present invention that the angle is set and the computer controls the steering mechanism so that the actual steering angle of the work machine wheel becomes the target steering angle.

As a steering mechanism, an electric type or a hydraulic type,
Alternatively, an electro-hydraulic actuator is used, and as the sensor, a rotary potentiometer, a linear potentiometer, a rotary encoder, or the like is used.

Since the yawing increases in proportion to the offset amount, in order to set the steering angle of the working machine wheel that cancels the yawing, in the case of variable hitch angle traction, the working machine center of gravity is on the traction axis. Based on the hitch angle at 0, it is necessary to correct the actual hitch angle to a calculated hitch angle in consideration of the offset amount between the tractor and the work implement. The actual hitch angle is θA '(clockwise) and the calculated hitch angle is θ
When A and the angle correction are α, the following equation is obtained.

ΘA = θA '+ α

The angle correction α is in the range of the actual hitch angle θA '± 20%. Here, if θF is a hitch angle in a state where the work machine center of gravity is located on the tractor pulling axis, and k is a constant determined by mechanical characteristics and use conditions, for example, a constant value of 5 to 10, the angle correction α is given by the following equation. You can ask.

Α = (θA'-θF) / k

When the drawbar angle (counterclockwise) is θB, θA = θB when the tractor advancing direction coincides with the advancing direction of the working machine, and θA> θB when the working machine deviates to the right with respect to the advancing direction. When the work implement shifts to the left with respect to the traveling direction, θA <θB.

The deviation angle between the traveling direction of the tractor and the working machine is θ
If C, then θC = θA−θB. This deviation angle is θ
The steering angle of the wheel with respect to the axle for setting D is θD = θR−θC, where θR (normally right angle) is the neutral angle of the wheel. The computer determines the actual steering angle θ of the signal from the wheel sensor.
The steering mechanism is controlled so that E matches the target steering angle θD.

In the case of a trailer vehicle having a long working machine, θ
With the target steering angle calculated by D = θR−θC, sufficient turning performance may not be obtained during a sharp turn. Therefore, the angle correction β is inserted to make θD = θR−βθC. In a normal turning state, for example, a turning angle of ± 10 degrees or less, β = 1,
In a sharp turning state, for example, when the turning angle is ± 11 degrees or more,
When β> 1, for example, β = 2, even a long trailer vehicle can carry out smooth sharp turns with stepless control.

For fixed hitch angle traction, the hitch angle is typically square. When the hitch is fixed to the working machine so that the center of gravity of the working machine is located in the vertical plane including the centerline of the hitch, and when the hitch is pivotally supported on the drawbar so that the pivot point can slide in the drawbar axial direction, Set θC = -θB and set θ
Let D = θR−θC = θR + θB.

Further, a hitch is provided on the work machine such that a vertical plane including the center line of the hitch is movable in the axle direction of the work machine, and the hitch is pivotally supported on the draw bar so that the pivot point is located at the center of the draw bar. Also at this time, θC = −θB can be set by moving the hitch so that the center of gravity of the working machine is located in the vertical plane including the center line of the hitch.

By the above means, the wheel steering system for a towed work machine according to the present invention automatically controls the wheel steering angle of the work machine so as to always cancel the yawing that occurs in the work machine in the offset towing state. The tractor can reliably tow and advance the work implement even if the offset amount is large and the road surface friction resistance is small.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described based on the embodiment shown in FIG. FIG. 1 shows a tractor 1 for variable hitch angle traction.
FIG. 3 is a plan view of the working machine 2, in which a solid line indicates offset traction and a chain line indicates non-offset traction.

The tractor 1 moves straight in the direction of the arrow, and in the case of offset towing indicated by the solid line, the center of gravity G of the towed work machine 2 is at a position separated from the towing axis L by a predetermined offset amount. In the case of zero-offset traction without offset indicated by the chain line, the center of gravity of the towed work machine is located on the traction axis L.

A drawbar sensor 5 is provided at a connecting portion between the drawbar 3 and the hitch 4 arranged parallel to the wheel axle of the tractor 1, and a hitch sensor 6 is provided at a connecting portion between the hitch and the working machine 2. A wheel rudder angle sensor 9 is provided at a mounting portion of one wheel 8 of an axle 7 of the work machine 2, and the wheel 8 is steered by a hydraulic cylinder 10 provided at the work machine 2. A hitch cylinder 12 that adjusts an actual hitch angle that determines an offset amount is provided between the work machine 2 and the hitch 4.

A computer 11 for controlling the hydraulic cylinder 10 is arranged on the tractor 1, and a drawbar sensor 5 is provided.
Is a signal of a drawbar angle θB which is an intersection angle between the drawbar 3 and the hitch 4, and a hitch sensor 6 is a signal of an actual hitch angle θA ′ which is an intersection angle between the hitch and the axle 7 of the working machine 2,
The wheel sensor 9 measures the actual steering angle θE of the wheel 8 with respect to the axle 7.
The respective signals are input to the computer 11. Hitch angle θF during normal towing with zero offset indicated by chain line
Is programmed in the computer 11.

Based on these signals, the computer 11 calculates the calculated hitch angle θA in consideration of the offset amount between the tractor and the working machine and the deviation angle θC of the working machine 2 with respect to the traveling direction of the tractor 1, and The target steering angle θD of the wheel 8 for correcting the deviation angle is set, and the actual steering angle θE is set to the target steering angle θD.
The hydraulic cylinder 10 is operated so as to attain D.

The control of the computer 11 is executed in the automatic steering mode, as shown in the flow chart of FIG. In the mode switching operation in step 1, if it is not switched to OFF, in step 2,
The neutral angle θR of the wheel with respect to the axle is set, and in steps 3, 4 and 5, the hitch angle θA, the drawbar angle θB,
The actual steering angle θE of the wheel is input and averaged in step 6 to remove noise.

Next, in step 7, the actual hitch angle (clockwise) θA 'is corrected to the actual hitch angle θA' in order to correct the calculated hitch angle in consideration of the offset amount between the tractor and the working machine to θA '. Add. As described above, if θF is a hitch angle in a state where the work machine center of gravity is located on the tractor pulling axis, and k is a constant determined by mechanical characteristics and use conditions, for example, a constant value of 5 to 10, the angle correction α Can be calculated by the following equation. α = (θA'-θ
F) / k

In the next step 8, θC = θA−θ
By B, the deviation angle θ of the working machine with respect to the traveling direction of the tractor
C is calculated, and in step 9, θD = θR−βθ
The target steering angle θD of the wheel is determined by C, and step 1
At 0, the difference S between the actual steering angle of the wheel and the target steering angle is calculated by S = θE−θD, and at step 11, if S is within the dead zone, return to step 1, otherwise go to step 1. , Positive or negative is determined in step 12, and if positive, a right steering signal is output to the hydraulic cylinder in step 13, and if negative, a left steering signal is output to the hydraulic cylinder in step 14, and the wheels are steered to the right or left. Cut off. Then, the process returns to step 1 and the process is repeated again, so that the yawing of the working machine 2 is automatically corrected and the traveling direction of the working machine coincides with the traveling direction of the tractor and goes straight.

[0027]

EXAMPLE Another example will be described based on the example shown in FIG. FIG. 3 is a plan view schematically showing a work machine that is offset towed by a tractor and a fixed hitch angle.

In the embodiment shown in FIG. 3 (a), the hitch 4 is fixed to the working machine 2 at a right angle to the axle 7 so that the center of gravity of the working machine 2 is located in a vertical plane including the center line of the hitch 4. The hitch 4 is connected to the drawbar 3 via the pin 13, and the pin is moved by an offset amount H in the axial direction of the drawbar 4 via the offset cylinder 14 provided in the drawbar 3 to enable offset towing of the working machine. And
It does not have a hitch sensor.

In the embodiment shown in FIG. 3 (b), the hitch 4 is provided on the working machine 2 so that the vertical plane including the center line of the hitch 4 can be moved in parallel with the axle 7 of the working machine 2, and the axis fulcrum is The hitch 4 is pivotally supported on the drawbar 3 so as to be located at the center of the drawbar 3. Hitch 4 supported by work implement 2 at right angles to axle 7.
Is moved by an offset amount H in the axial direction of the axle 7 via an offset cylinder 15 provided in the working machine 2 so that the working machine can be offset towed without a hitch sensor. The configuration other than the above is the same as the embodiment of FIG.

The computer 11 has a drawbar sensor 5
Based on the drawbar angle θB signal of the tractor 1, the deviation angle θC with respect to the neutral angle θR (normally right angle) of the work machine 2 wheel 8 with respect to the traveling direction of the tractor 1 is calculated, and the target steering angle θD of the wheel 8 for correcting the deviation angle is calculated. With the equation θD = θR−θC = θR
It is set by + θB, and the hydraulic cylinder 10 is operated so that the actual steering angle θE becomes the target steering angle. As a result, the working machine 2
Yawing is automatically corrected, and the traveling direction of the work machine coincides with the traveling direction of the tractor 1.

[0031]

As described above, the wheel steering system according to the present invention is different from the conventional yaw generated on the working machine in the offset towed state, which is different from the yaw generated on the working machine in the offset towed state. Since the wheel steering angle of the work machine is automatically controlled so that
The tractor has an excellent effect that the working machine can be reliably towed and advanced in the traveling direction of the tractor even if the offset amount is large or the frictional resistance of the road surface is small.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a work machine equipped with a wheel steering system according to an embodiment of the present invention and offset towed by a tractor and a variable hitch angle;

2 is a flowchart of the wheel steering system of FIG. 1,

FIG. 3 is a plan view schematically showing a working machine equipped with a wheel steering system of another embodiment and offset towed by a tractor and a fixed hitch angle, an offset cylinder, (a) a drawbar, and (b). Is installed on the work machine.

4A and 4B are plan views schematically showing yawing of a tractor and a working machine in an offset towing state in a conventional example, FIG. 4A showing a state before starting, and FIG. 4B showing a yawing state.

[Explanation of symbols]

1: Tractor 2: Work implement 3: Drawbar 4: Hitch 5: Drawbar sensor 6: Hitch sensor 7: Axle 8: Wheel 9: Wheel sensor 10: Hydraulic cylinder 11: Computer 12: Hitch cylinder 13: Pins 14, 15: Offset Cylinders α, β: Angle correction θA: Calculated hitch angle θA ′: Actual hitch angle θB: Drawbar angle θC: Deviation angle θD: Target rudder angle θE: Actual rudder angle θF: Hitch angle (the work center of gravity is pulled by the tractor Positioned on the axis) θR: Neutral angle G: Center of gravity (working machine) H: Offset amount L: Traction axis S: Angle difference

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideyasu Okada             Obihiro City West Article 22 North 1-2-5 Toyo Agricultural Machinery             Within the corporation (72) Inventor Yukio Miyashita             Obihiro City West Article 22 North 1-2-5 Toyo Agricultural Machinery             Within the corporation (72) Inventor Toshinobu Ohashi             Obihiro City West Article 22 North 1-2-5 Toyo Agricultural Machinery             Within the corporation (72) Inventor Shinobu Murase             Obihiro City West Article 22 North 1-2-5 Toyo Agricultural Machinery             Within the corporation F term (reference) 2B043 AA04 AB06 BA02 BB01 DA04                       DA15 DC03 EA16 EC13 EC14                       ED02 ED13                 3D032 CC01 DA03 DB11 DD02 EA10                       EB04 EC01 GG05 GG12

Claims (3)

[Claims] 1. A steering mechanism (10) for operating wheels (8) of a working machine (2), a computer (11) for controlling the steering mechanism, a wheel axle of a tractor (1) or a drawbar (3). A drawbar sensor (5) for detecting a drawbar angle (θB) which is an intersection angle of the hitch (4), and a hitch sensor for detecting an actual hitch angle (θA ′) which is an intersection angle of the hitch and the wheel axle of the working machine. (6) and a wheel sensor (9) for detecting the actual steering angle (θE) of the wheels of the working machine, the wheel steering apparatus for the working machine,
When the signals of the drawbar sensor and the hitch sensor are input, the computer calculates a hitch angle (θ) in consideration of an offset amount between the tractor and the working machine.
A) is calculated, and then a deviation angle (θC) in the traveling direction of the tractor and the working machine is calculated to set a target steering angle (θD) of the wheels, and the actual steering angle matches the target steering angle. A steering device for a towing type work machine, comprising: 2. The target rudder angle is as follows: θR: neutral angle of work machine wheel θF: hitch angle k in a state where the work machine center of gravity is located on the tractor traction axis: constant (1 to 5: depending on use conditions) β: Angle correction (normal turn: β = 1, sudden turn: β>
The wheel of the towed work machine according to claim 1, wherein the following equation is set: (1) where θA = θA ′ + (θA′−θF) / k θC = θA−θB θD = θR−βθC. Steering device. 3. A drawbar sensor (5) for detecting a drawbar angle (θB) between a hitch (4) and a wheel axle or a drawbar (3) of a tractor (1) that pulls a work machine (2) at a fixed hitch angle. And the actual steering angle of the wheels of the working machine (θ
E), a wheel sensor (9), a hydraulic mechanism (10) that steers the wheels, and a signal from the drawbar sensor, the shift angle (θC) between the tractor and the working machine in the traveling direction is input. Wheel steering of a towed work machine comprising a computer (11) that calculates and sets a target steering angle (θD) of the wheels and controls the hydraulic mechanism so that the actual steering angle matches the target steering angle. In the device, the hitch is fixed to the working machine so that the center of gravity of the working machine is located in a vertical plane including the center line of the hitch, and the hitch is pivotally supported on the drawbar in the axial direction of the drawbar. When the slidable shaft is supported, or the vertical plane including the center line of the hitch is movable in the axial direction of the working machine, the hitch is provided on the working machine, and the hitch is pivotally supported on the drawbar. Drawbar When the shaft is supported so as to be located at the center of the wheel, the target rudder angle is set by the formula θC = −θB θD = θR−θC, where θR is the neutral angle of the work machine wheel. Wheel steering device for towed work machines.