JP2003205850A - Steering controller for mobile agricultural machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To operate a brake device and a front wheel acceleration device by a simple hydraulic circuit configuration. <P>SOLUTION: A steering controller for a tractor 10 is constituted in such a way that a solenoid selector valve 40 for switching and controlling a pair of right and left pipes 103R, 103L is arranged in a pair of right and left pipes 103R, 103L for supplying pressure oil into and discharging pressure oil from a pair of right and left brake cylinders 50R, 50L and a high pressure priority type shuttle valve 42 connected with a pair of right and left pipes 103R, 103L in parallel is provided between the solenoid selector valve 40 and the brake cylinders 50R, 50L to supply pressure oil to a QT piston 28 through the high pressure priority type shuttle valve 42 so that both of the brake cylinders 50R, 50L and the QT piston 28 can be operated by the simple hydraulic circuit configuration. <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 steering control device for a mobile agricultural machine, and more particularly to a mobile agricultural machine equipped with a hydraulic actuator for braking and a hydraulic actuator for accelerating front wheels, which are provided corresponding to the left and right rear wheels. The present invention relates to a steering control device.

[0002]

2. Description of the Related Art In a mobile agricultural machine such as a tractor, for example, when the steering angle of the front wheels exceeds a predetermined value in order to carry the vehicle around the ridge with a small turning radius, the front wheel speed increasing device is used. There is known a technique in which a sharp turning is made possible by making the rotational peripheral speed of the vehicle faster than the rotational peripheral speed of the rear wheel and automatically applying a braking action to the rear wheel on the inside of the turning by a brake device.

For example, as shown in FIG. 3, in a conventional tractor, a lift hydraulic circuit 180 and a brake device 146 are used.
And the like, and a hydraulic pump 156 ′ for supplying pressure oil to the hydraulic cylinder 130 of the power steering unit 152. The steering wheel 122 is operated to change the steering angle of the front wheels. Is equal to or greater than a predetermined value, pressure oil is supplied from the hydraulic pump 156 to the front wheel speed increasing device 126 via the flow dividing valve 134 to operate the front wheel speed increasing device 126, and the brake device via the direction control valve 170. Pressure oil is also supplied to 146, and a brake cylinder (150R or 150R) inside the turning is provided.
L) was designed to work automatically.

[0004]

However, according to the above-mentioned conventional example, in order to supply the pressure oil from the hydraulic pump 156 to the front wheel speed increasing device 126, the brake device 146, the hydraulic circuit 180 for the lift, and the like, The expensive shunt valve 1 mentioned above
34, the directional control valve 170, etc. had to be provided.

In particular, the diversion valve 134 is a valve for diverting the flow rate from the hydraulic pump 156 to each port by an electric signal from the outside, and its structure is a decompression for reducing the main circuit pressure to the piston side pressure. Valve 160 and solenoid type switching valve 136 for intermittently switching the piston side pressure
And the sequence valve 164 that secures the piston side pressure when the main circuit is unloaded. The diversion valve 134 and the direction control valve 170 complicate the hydraulic circuit and increase the manufacturing cost. There was a problem of becoming.

The present invention has been made to solve the above problems, and an object of the present invention is to enable a brake device and a front wheel speed increasing device to operate with a simple hydraulic circuit structure and to manufacture them. It is an object of the present invention to provide a steering control device for a mobile agricultural machine that can reduce costs and the like.

[0007]

In order to achieve the above object, the invention according to claim 1 is based on the fact that the steering angle of the front wheels (12) is equal to or more than a predetermined value, and the rear wheels (14) on the inside of the turn. ) To apply a braking action to the left and right rear wheels (14R, 14L) provided in correspondence with the pair of left and right hydraulic actuators for braking (50R, 50L) and the front wheels (12) to the rear wheel (12). A steering control device for a mobile agricultural machine (10) comprising a front wheel speed-increasing hydraulic actuator (28) that is faster than the rotational speed of (14).
L) a pair of left and right oil passages (103R, 10R) for supplying and discharging pressure oil.
3L) and the pair of left and right oil passages (103R, 10R)
3L) switching valve (40) for switching control, the switching valve (40) and the brake hydraulic actuator (50)
R, 50L), the pair of left and right oil passages (1
03R, 103L), and a high pressure selection valve (42) connected in parallel to the front wheel speed increasing hydraulic actuator (28) via the high pressure selection valve (42). And

According to a second aspect of the present invention, in the steering control device for a mobile agricultural machine according to the first aspect, the high pressure selection valve (4) in the pair of left and right oil passages (103R, 103L).
An on / off valve (44) for switching between communication and disconnection is provided between the branch portion (c, d) of 2) and the brake hydraulic actuator (50R, 50L).

[Operation] According to the steering control device for a mobile agricultural machine according to the present invention, a pair of left and right oil passages (103R, 103R, 50R, 50L) for supplying and discharging pressure oil to the pair of left and right hydraulic actuators for braking (50R, 50L). 103 L), the pair of left and right oil passages (103
A switching valve (40) for switching and controlling the R, 103L) is arranged, and the pair of left and right oil passages (103R) are provided between the switching valve (40) and the brake hydraulic actuator (50R, 50L). , 103L) is provided with a high pressure selection valve (42) connected in parallel, and the front wheel speed increasing hydraulic actuator (2) is provided via this high pressure selection valve (42).
Since the pressure oil is supplied to 8), the brake hydraulic actuators (50R, 50R) have a simple hydraulic circuit configuration.
Both L) and the front wheel speed increasing hydraulic actuator (28) can be operated.

The reference numerals in parentheses refer to the drawings and do not limit the present invention in any way.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of a steering control device for a tractor as a mobile agricultural machine to which the present invention is applied. In the figure, the tractor 10 includes a pair of left and right front wheels 12R,
12L and rear wheels 14R and 14L support the engine 18 at the front of the vehicle and the mission case 2 at the rear.
0, steering wheel 2 in the upper driver's seat in the center of the aircraft
It has 2 etc. The power of the engine 18 is transmitted to the left and right rear wheels 14R and 14L via a main transmission and an auxiliary transmission (not shown) in the transmission case 20, and the power branched from the front stage of the rear wheel differential mechanism (not shown). Are transmitted to the left and right front wheels 12R and 12L via the transmission shaft 16.

FIG. 2 shows a steering control device for a tractor according to the present embodiment. This steering control device includes a power steering cylinder 30 that applies a steering force to the front wheels 12 by hydraulic pressure, and a power steering hydraulic circuit 60. The power steering hydraulic circuit 60 is connected to a hydraulic pump 56. A switching valve 54 for switching the oil passage of the pipe 100, a metering pump 53 with servo feedback integrated with the switching valve 54, and a pipe for supplying pressure oil from the pipe 100 to the power steering cylinder 30 via the switching valve 54. 101R, 10
1L and. In the metering pump 53, when the rotation angle of the steering wheel 22 changes, the discharge pressure of the hydraulic pump 56 becomes the pilot pressure and the switching valve 54 operates.

That is, when the steering wheel 22 is turned to the left or right, the switching valve 54 is switched by the rotation of the steering wheel 22, and the hydraulic oil in the tank 57 is transferred from the pipe 100 to the pipe 101R ( Or 101L), the oil is supplied to the oil chamber on one side of the double-acting power steering cylinder 30, whereby the tie rod (not shown) of the front axle is hydraulically steered. At this time, the pressure oil (and surplus oil) discharged from the oil chamber on the other side of the power steering cylinder 30 is supplied to the pipe 102 side.

In the power steering system according to the present embodiment, even when the engine 18 is stopped, the pressure oil is circulated in the power steering hydraulic circuit 60 via the check valve 55, and the power steering cylinder 3 is operated.
An all-hydraulic power steering device is employed which is capable of steering the steering wheel 22 by hydraulic pressure when pressure oil is supplied toward zero.

Here, in the present embodiment, the pair of left and right oil passages 103R and 103L for supplying and discharging the pressure oil to and from the pair of left and right brake hydraulic actuators 50R and 50L are arranged,
A switching valve 40 for switching and controlling the pair of left and right oil passages, the switching valve 40 and a brake hydraulic actuator 50R,
Between 50 L, a high pressure selection valve 42 connected in parallel to the pair of left and right oil passages is provided.

In FIG. 2, the amount of movement of the rod of the power steering cylinder 30 is detected by a steering angle sensor (not shown). The detection value at this time, that is, the steering steering angle of the front wheels 12 is detected. When reaches a constant value, the turning angle sensor outputs an ON signal,
Based on this ON signal, the electromagnetic switching valve 40 performs switching operation. As a result, pressure oil is supplied from the pipe 102 to the pair of left and right pipes 103R or 103L via the electromagnetic switching valve 40.

This pair of left and right pipes 103R or 103L
Are arranged to supply and discharge pressure oil to and from a pair of left and right brake cylinders (brake hydraulic actuators) 50R and 50L provided corresponding to the left and right rear wheels 14R and 14L. Further, a front wheel speed increasing device 26 operated by pressure oil is attached to the mission case 20. The front wheel speed increasing device 26 includes a QT piston (a front wheel speed increasing hydraulic actuator) 28 and a QT clutch 27, and QT is applied by pressure oil.
As the T-piston 28 moves, the QT clutch 27
Are connected and the front wheels 12 are accelerated.

That is, when the steering angle of the front wheels 12 exceeds a predetermined value, the electromagnetic switching valve 40 is switched, whereby pressure oil is supplied from the pipe 102 to the piping 103R or 103L side via the electromagnetic switching valve 40. To be done. The pressure oil causes the rear wheel 14R on the inside of the turn to rotate.
Brake cylinder 50R (or 50L) arranged corresponding to (or 14L) is operated by pressure oil, and a braking force is applied to rear wheel 14R (or 14L) on the inside of the turn. At approximately the same time as this, the front wheel speed increasing device 26 operates,
The rotational peripheral speed of the front wheels 12 is increased to be approximately double that of the rear wheels 14.

As shown in FIG. 1, the left and right rear wheels 14R, 14L are provided with a pair of left and right brakes 46R, 46L corresponding to these and independently operable. When the operation pedals 48R, 48L are depressed, a braking force is applied to the left and right rear wheels 14R, 14L by the brakes 46R, 46L mechanically connected via the brake rods 49R, 49L.

Further, the brakes 46R and 46L are also operated by hydraulic pressure, and are discharged from the power steering cylinder 30 side based on an ON signal from the turning angle sensor by turning operation of the steering wheel 22. The pressure oil is applied to the rear wheel 14R (or 14
L) is supplied to a brake cylinder 50R (or 50L) provided corresponding to the brake 46R (or 4).
6L) is automatically activated.

As described above, when the front wheels 12 are steered, pressure oil is supplied from the power steering hydraulic circuit 60 to the power steering cylinder 30, and the pressure oil discharged from the power steering cylinder 30 is supplied to the pipe 10.
It is supplied to the 2 side. Further, when the steering angle of the front wheels 12 exceeds a predetermined value, the solenoid of the electromagnetic switching valve 40 on the side corresponding to the rear wheel 14R (or 14L) on the inside of the turn is excited and switched by an ON signal from the angle sensor. .

Thus, the power steering cylinder 3
The pressure oil discharged from 0 to the pipe 102 side is provided through the pipe 102 and the electromagnetic switching valve 40 to the brake cylinder 50R provided corresponding to the rear wheel 14R (or 14L) on the inside of the turn.
It is supplied to the pipe 103R (or 103L) on the (or 50L) side. And this piping 103R (or 103L)
The brake cylinder 50R (or 50L) is supplied with pressure oil from the brake cylinder 50R to brake the rear wheel 14R (or 14L).

On the other hand, a pair of left and right pipes 103 is provided between the electromagnetic switching valve 40 and the brake cylinders 50R and 50L.
A high pressure priority type shuttle valve 42 connected in parallel to the R and 103L is provided. The high pressure priority type shuttle valve 42 is a valve that receives the pressure oil on the high pressure side of the pressure oil supplied from the pair of left and right pipes 103R and 103L.
Then, pressure oil is supplied from the high pressure priority type shuttle valve 42 to the front wheel speed increasing device 26, and the QT piston 28 is operated.

Therefore, when the steering angle of the front wheels 12 exceeds a predetermined value, the rear wheels 14R (or 1) on the inside of the turn are turned.
4L) corresponding to the brake cylinder 50R
(Or 50 L), the pressure oil is supplied to the front wheel speed increasing device 26 via the high pressure priority type shuttle valve 42.

The brake cylinder 50R (or 5)
0L) pressure oil supplied to the rear wheel 14R on the inside of the turn.
(Or 14 L) is applied with the braking force, and the pressure oil supplied to the front wheel speed increasing device 26 causes the QT piston 2
8 operates to connect the QT clutch 27, and the rotational peripheral speed of the front wheels 12 rotates at about twice the rotational peripheral speed of the rear wheels 14. In this way, the front wheels 12 are rotated at a higher speed than the rear wheels 14, and the machine body rotates around the rear wheels 14 on the inside of the turning, so that the machine body can make a turn with a small turning radius.

Further, according to the present embodiment, one electromagnetic switching valve 40 is provided in the pair of left and right pipes 103R and 103L for supplying and discharging the pressure oil to and from the brake cylinders 50R and 50L. Both of the brake cylinders 50R and 50L and the QT piston 28 can be operated by the hydraulic circuit configuration.

Next, in the present embodiment, between the branch hydraulic pressure actuator 50 and the branch portions c and d of the high pressure selection valve 42 in the pair of left and right pipes 103R and 103L.
An on / off valve 52 for switching between communication and shutoff is provided.

That is, a pair of left and right pipes 103R, 10
3L is a brake cylinder 50 via branch parts c and d.
R, 50L and the high pressure priority type shuttle valve 42 are connected to each other, and the branch parts c, d and the brake cylinders 50R,
Manual switching valves 52R and 52L are provided between the switch 50L and 50L. Then, by manually operating the manual switching valves 52R, 52L, the brake cylinders 50R, 5L
The supply of pressure oil to 0L can be connected or cut off.

Therefore, the manual switching valves 52R, 52
If L is switched to the shut-off side, the front wheel speed increasing device 26 will be activated when the steering angle of the front wheels 12 exceeds a predetermined value.
And only the manual switching valves 52R, 5 become operable.
If 2L is switched to the communication side, the brake 46R (or 46L) on the side corresponding to the rear wheel 14 on the inside of the turn and the front wheel speed increasing device 26 are operated when the steering angle of the front wheel 12 exceeds a predetermined value. Both are operational. This allows
The operator can arbitrarily adjust the turning performance of the machine body according to the road surface condition of the field.

A relief valve 44 is communicated with the pipe 102, and the relief valve 44 serves to keep the pressure in the pipe 102 substantially constant.

Next, the operation of this embodiment will be described.

In FIG. 2, for example, when the steering wheel 22 is turned to the right, the switching valve 54 in the power steering hydraulic circuit 60 is switched to the p side, and the pressure oil in the pipe 100 connected to the hydraulic pump 56 is discharged. After being supplied to the oil chamber on the right side of the power steering cylinder 30 through the metering pump 53 and the pipe 101R, the rod in the cylinder moves to move the steering wheel 22.
The steering force by hydraulic pressure is applied to.

Further, during this turning operation, the pressure oil (and the surplus oil) discharged from the oil chamber on the left side of the power steering cylinder 30 is supplied to the pipe 102 side, but the cutting angle of the front wheel 12 is increased. When the value exceeds a predetermined value (for example, an angle of 40 degrees), the solenoid b of the electromagnetic switching valve 40 is energized by an electric signal from the cut angle sensor to switch the valve. As a result, the pressure oil from the pipe 102 is supplied to the pipe 103R via the electromagnetic switching valve 40, further passes through the manual switching valve 52R, and is supplied to the brake cylinder 50R of the right rear wheel 14R to operate the brake. The pressure control of the pressure oil flowing through the pipes 102, 103R, 103L is performed by the relief valve 44.

Further, the pressure oil supplied to the pipe 103R is
The QT piston 28 of the front wheel speed increasing device 26 moves via the high-pressure priority type shuttle valve 42 and the QT clutch 27 is connected, whereby the peripheral speed of the front wheel 12 is approximately twice that of the rear wheel 14. Rotate at the speed of. Thus, the front wheels 12
Is rotated at an increased speed and the rear wheel 1
Since the braking force acts on the 4R, the airframe can turn with a small radius around the rear wheel 14R on the inside of the turn as a substantial center.

Next, when the steering wheel 22 is returned to the original neutral position side, the solenoid b of the electromagnetic switching valve 40 is returned.
Is turned off, the electromagnetic switching valve 40 returns to the neutral position, and the pressure oil in the pipe 103R is returned to the tank 57 '.

As described above, according to the present embodiment, the left and right sides for supplying and discharging the pressure oil to and from the brake cylinders 50R and 50L.
An electromagnetic switching valve 40 is arranged in the pair of pipes 103R and 103L, and the electromagnetic switching valve 40 and the brake cylinder 50R,
Between 50L, a pair of left and right pipes 103R, 10
Since the high pressure priority type shuttle valve 42 is connected in parallel to the 3L, one electromagnetic switching valve 40 is provided in the pair of left and right pipes 103R and 103L. Both the piston 28 can be activated.

[0038]

According to the first aspect of the present invention, there is provided a switching valve disposed in a pair of left and right oil passages for supplying and discharging pressure oil to and from the braking hydraulic actuator, and the switching valve and the braking hydraulic actuator. Between the left and right oil passages, a high pressure selection valve connected in parallel is provided, and the pressure oil is supplied to the front wheel speed increasing hydraulic actuator via the high pressure selection valve. With the configuration, the brake hydraulic actuator and the front wheel speed increasing hydraulic actuator can be operated, and an expensive switching valve is provided.
Since only one piece is required, it is possible to reduce the manufacturing cost and the mounting space.

According to a second aspect of the present invention, in the steering control device for a mobile agricultural machine according to the first aspect, there is provided between the pair of left and right oil passages between the branch portion of the high pressure selection valve and the brake hydraulic actuator. Since a shut-off valve is provided, by operating this on-off valve, it is possible to operate only the front wheel speed-increasing hydraulic actuator or both the front wheel speed-increasing hydraulic actuator and the brake hydraulic actuator. Therefore, the operator can arbitrarily adjust the turning performance of the machine body according to the road surface condition of the field and the like.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a steering control device for a mobile agricultural machine according to the present invention.

FIG. 2 is a diagram showing an embodiment of the hydraulic circuit of the above.

FIG. 3 is a diagram showing an embodiment of a conventional hydraulic circuit.

[Explanation of symbols]

10 Tractor 12 Front Wheel 14 Rear Wheel 22 Steering Wheel 26 Front Wheel Accelerator 27 QT Clutch 28 QT Piston (Front Wheel Accelerator Hydraulic Actuator) 30 Power Steering Cylinder 40 Electromagnetic Switching Valve (Switching Valve) 42 High Pressure Priority Shuttle Valve (High Pressure Selection) Valve) 46R, 46L Brake 50R, 50L Brake cylinder (hydraulic actuator for brake) 52R, 52L Manual switching valve (on / off valve) 56 Hydraulic pump 57, 57 'Tank 60 Hydraulic circuit for power steering 103R, 103L Piping (oil passage)

Continued front page    F-term (reference) 3D043 AA03 AA06 AB12 AB17 EA02                       EA12 EA16 EA44 EB02 EB06                       EB09 EB14 EE09 EE12 EE16                       EF16 EF19                 3D052 AA02 BB08 DD03 EE02 FF02                       FF05 GG03 HH02 JJ17 JJ23                 3H089 AA73 BB27 CC01 CC12 DA02                       DA07 DB37 DB44 DB48 EE31                       FF03 GG02 JJ17

Claims (2)

[Claims] 1. A pair of left and right brakes provided corresponding to the left and right rear wheels to apply a braking action to the rear wheels on the inside of the turn, based on the steering angle of the front wheels exceeding a predetermined value. In a steering control device for a mobile agricultural machine, which includes a hydraulic actuator and a front wheel speed increasing hydraulic actuator that increases the rotation speed of the front wheels more than the rotation speed of the rear wheels, pressure oil is supplied to the pair of left and right brake hydraulic actuators. A switching valve disposed in a pair of left and right oil passages for supplying and discharging, and a switching valve for switching control of the left and right pair of oil passages, and the pair of left and right oil passages between the switching valve and the brake hydraulic actuator. And a high pressure selection valve connected in parallel with each other, wherein pressure oil is supplied to the front wheel speed increasing hydraulic actuator via the high pressure selection valve. 2. An on / off valve for switching between communication and disconnection is provided between a branch portion of the high pressure selection valve and the brake hydraulic actuator in the pair of left and right oil passages. 1. A steering control device for a mobile agricultural machine according to 1.