JPS6336703A - Steering control unit of working vehicle - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a work vehicle that is configured to be able to freely operate power steering on both front and rear wheels, and that is equipped with a main transmission device and an auxiliary transmission device for traveling transmission. The present invention relates to a steering control device.

[Conventional technology]

In this type of work vehicle, it is also possible to use a two-wheel steering type in which only the front wheels are steered, and a four-wheel steering type in which sharp turns can be made by steering the front and rear wheels in opposite directions. As such, both the front and rear wheels can be operated with power steering.

Also, when not working such as driving on the road, reduce the driving speed slightly.
P4 Although it is not necessary to flff, it is desirable to travel at high speed, and conversely, although it is not necessary to travel at high speed, it is desirable to finely adjust the travel speed during work. In addition to the main transmission for driving,
A sub-transmission is provided.

By the way, since it is troublesome to manually switch between the two-wheel steering type and the four-wheel steering type, conventionally, a traveling speed detection means for detecting the traveling speed changed by the main transmission and the auxiliary transmission has been used. provided, and when the traveling speed becomes higher than the set speed, the two-wheel steering type is activated, and
A steering type switching means is provided to automatically switch the steering type based on the detection information G of the traveling speed detecting means so that the four-wheel steering type is selected when the traveling speed is less than a set speed.

[Problem that the invention seeks to solve]

According to the above-mentioned conventional means, both when switching the sub-transmission to the low-speed side and when switching to the high-speed side, as the traveling speed changes due to the shift operation of the main transmission, 2.
Since the steering type is switched between the two-wheel steering type and the four-wheel steering type, and the switching operation of the steering type is difficult for the operator to understand, there is a disadvantage that it is difficult to perform steering operations well.

In other words, for example, if you want to make a sharp turn with 4-wheel steering while working, but the steering mode is switched to 2-wheel steering, you will not be able to make a sharp turn at the edge of a ridge, etc. If the steering type was changed depending on the driving speed, there was a risk of steering errors, such as the possibility of the vehicle hitting a ridge or the like.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to suppress steering errors even though the steering type is automatically switched.

Means for Solving Problem C] The characteristic configuration of the steering control device for a working vehicle according to the present invention is that it is provided with an auxiliary transmission position detection means for detecting a switching position of the auxiliary transmission, and that the auxiliary transmission is operated at high speed. When the sub-transmission is switched to the low-speed side, the steering operation is performed in a two-wheel steering type in which only the front wheels are steered, and when the sub-transmission is switched to the low-speed side, both the front and rear wheels are steered. In order to perform a steering operation in a wheel steering type, a steering type switching means is provided for automatically switching the steering type based on the detection information by the auxiliary shift position detection means, and its operation and effect are as follows. That's right.

[For production]

In other words, during work, a four-wheel steering type is strongly desired, as the end of each work stroke must be made to make sharp turns to drive the vehicle toward the start of the next work stroke. On the other hand, when the vehicle is not working, such as when stopping, the auxiliary transmission is operated to the lower speed side, focusing on the fact that two-wheel steering is highly desirable in order to avoid sharp turns while traveling at high speed. When working,
The steering type is automatically switched according to the operation of the auxiliary transmission so that it becomes a 4-wheel steering type and becomes a 2-wheel steering type when the auxiliary transmission is operated to the high speed side during non-work.

〔Effect of the invention〕

Therefore, it is now possible to automatically switch to a steering type suitable for both working and non-working situations, while suppressing steering errors caused by unnecessary switching of the steering type. As a result, it has become possible to perform appropriate steering operations while simplifying the operation.

C Example] Embodiments of the present invention will be described below based on the drawings.

As shown in Figure 3, a lawn mowing device (1) driven by the output of the engine (E) is mounted on the underbelly of the aircraft (V), which can be operated both remotely and on board. It consists of a work vehicle used for cutting grass, weeds, etc.

To explain the configuration of the aircraft (ν), as shown in FIGS. 2 and 3, a pair of left and right front wheels (2) and a pair of left and right rear wheels (3) can be freely steered. A steering hydraulic cylinder (4) serves as a steering actuator for separately operating the pair of front and rear wheels (2) and (3).

(5), and control valves (6), (7) for it
is provided. A hydraulic continuously variable transmission (8) as a main transmission that can freely switch forward and backward is coupled to the engine (E), and a speed change pedal (9) and a remote control as a speed change operation means for on-board operation are connected to the engine (E). A speed change motor (10) serving as a speed change actuator for steering is interlocked and connected to a speed change arm (11) of the speed change device (8) so that any speed can be changed freely. Further, the output of the transmission (8) is transmitted to the front and rear wheels (2) and (3) via an auxiliary transmission (13) configured to be able to freely switch between high speed and low speed using an auxiliary speed change lever (12). It is meant to be communicated.

Further, a steering handle (H) is provided as a means for indicating a target steering angle for boarding maneuver.

To explain the configuration of the steering control means, the control valves (6) of the steering hydraulic cylinders (4) and (5)
, (7), and a control device (14) constituting a steering control means for giving operation commands to each of the variable speed motors (10).
, a receiver (16) is provided which receives instruction information from a remote control transmitter (15) and transmits it to the control device (14).

Further, a target steering position detection potentiometer (Ro) that detects a target steering position during boarding maneuver that detects the operating position of the steering handle (I);
A front wheel steering position detection potentiometer (R9) that detects the steering position of the front wheel (2), a rear wheel steering position detection potentiometer (R2) that detects the steering position of the rear wheel (3), and Shift position detection potentiometers (R3) are provided to detect the position of the shift arm (11), that is, the shift position, and these potentiometers (Ro) to (R3) are provided.
) is input to the control device (14), and the control device (14) detects the transmitter (
15) or a steering control means for power steering the front and rear wheels (2) and (3) as steering wheels based on the target steering position instructed by the steering handle (11).

When operating the front and rear wheels (2) and (3) with power steering, there is a parallel steering type that changes the direction of the front and rear wheels (2) and (3) in the same direction, and a four-wheel steering type that changes the direction of the front and rear wheels (2) and (3) in the same direction and turns sharply. Type and front wheel (2)
This allows for the use of a two-wheel steering type that only changes direction. The configuration is such that the parallel steering type and the four-wheel steering type can be selected both during remote control and on-board operation. However, when the above-mentioned 4-wheel steering type is selected during boarding and maneuvering, the auxiliary transmission (13) changes between high-speed and low-speed so that the 4-wheel steering type is used at high speeds and the 4-wheel steering type is used at low speeds. It is configured to automatically switch the steering type in conjunction with the switching.

To explain the configuration of the transmitter (15), the transmission lever (17) instructs the shift position of the transmission (8) by its longitudinal movement, and the transmission lever (17) which instructs the shift position of the transmission (8) by its longitudinal movement, and controls the front wheel (2) or the rear wheel (3) by its horizontal movement. Instructs the target steering position, and
In addition to providing a steering lever (18) that instructs the steering type by moving forward and backward, each of the levers (17)
, (18) for detecting the operating position, and a transmitting device for transmitting information detected by the sensors as instruction information to the receiver (16).

That is, during remote control, the target shift position indicated by the shift lever (17) provided with the transmitter (15) matches the shift position detected by the shift position detection potentiometer (R3). Variable speed motor (10)
The target steering position indicated by the steering lever (18) and the steering position detection potentiometer (R+) are configured to control the operation of the steering lever (18).
- configured to control the operation of the control valves (6) and (7) of the steering hydraulic cylinders (4) and (5) so that the detection position by (Rz) coincides with the detection position,
The vehicle (V) automatically travels at the designated vehicle speed, and remotely controls the vehicle (V) so that the steering positions of the front and rear wheels (2) and (3) are in the designated steering position using the designated steering type. It is designed so that it can be operated.

To explain the configuration of boarding control, there is a control mode switch (19) that switches between boarding control and remote control.
information, a steering type selection switch (20) that selects the steering type during boarding operation, an auxiliary gear shift position detection switch (21) that detects the operating position of the auxiliary gear shift lever (13), and the steering handle (H ), that is, the detection information of the potentiometer (Ro) for detecting the target steering position during boarding maneuvers, is input into the control device (14), and based on the information, the steering hydraulic cylinder (4) .

(5) by controlling the operation of the control valves (6) and (7),
This allows power steering to be operated.

However, the shift position of the transmission (8) during boarding maneuvers, that is, the adjustment of the vehicle speed, is performed by directly operating the shift arm (11) with the shift pedal (9). The sub-shift lever (12) can be used to switch between high speed and low speed without having to operate the speed change lever (12).

and the steering type selection switch (20).
When the 4-wheel steering type is selected, as the sub-shift lever (12) is switched to the high speed side, the mode becomes the 2-wheel steering type, and as the sub-shift lever (12) is switched to the low speed side, the mode becomes the 4-wheel steering type. , the steering type will be automatically switched.

Next, the configuration of the steering type switching means (100) that switches the steering type in conjunction with the switching between high speed and low speed of the sub-transmission device (13) during the boarding operation will be explained.

As shown in FIG. 1, the steering handle (H)
A front wheel control valve drive circuit (22) that drives a front wheel control valve (6) based on an output voltage (Vi) from a target steering position detection potentiometer (Ro) that detects a target steering position indicated by ) and a rear wheel control drive circuit (23). Each control flight drive circuit (23), (23) receives a target voltage (Va), which is input based on the output voltage (Vi) from the target steering position detection potentiometer (Ro).
(Vb) and the front and rear wheels (2).

(3) The steering hydraulic cylinder (4) until the detected voltages of the respective steering position detection potentiometers (R1) and (Rg) match within the set dead zone.
, (5).

However, the front wheel control valve drive circuit (22) does not control the target steering position detection potentiometer (22) because the front wheels (2) are always steered regardless of the steering type. Output voltage from Ro) (
Vi) is input as is as the target voltage (Va).

On the other hand, the rear wheel control drive circuit (23) directs the rear wheels (3) in the same direction as the front wheels (2) when the parallel steering type is selected as the steering type is switched. For steering operation, the output voltage (Vi) from the target steering position detection potentiometer (Ro) is input as the target voltage (Vb), and when the four-wheel steering type is selected, the rear wheel (3) the front wheel (
2), the output voltage (Vi) from the target steering position detection potentiometer (Ro) is adjusted to a neutral voltage (Vn) set in advance corresponding to the neutral steering position. ) is input as the target voltage (Vb), and when the two-wheel steering type is selected, the neutral voltage (Vn) becomes the target voltage (Vb).
).

That is, the steering type selection switch (20)
and three analogs for switching the steering type, only one of which is maintained in the ON state depending on the operating state of the auxiliary shift position detection switch (21) that detects the operating position of the auxiliary shift lever (12). Switch (S, (S)
z), (S3), so that when the steering type selection switch (20) is switched to the parallel steering type side, the parallel steering type will be used regardless of the operating position of the auxiliary gear shift lever (12). Then, the output voltage (Vi) from the target steering position detection potentiometer (Ro) is applied to the rear wheel control valve drive circuit (23).
Only the first analog switch (S+) input to the switch is turned on.

Then, with the steering type selection switch (20) switched to the four-wheel steering type side, as the auxiliary gear shift lever (12) is switched to the low speed side, the auxiliary gear shift position detection switch (21) is turned off, and as the sub-shift lever (12) is switched to the high speed side, the sub-shift position detection switch (
21) is configured to operate ON, and outputs an "H" level switching signal when the sub-transmission position detection switch (21) is OFF, that is, when the sub-transmission (13) is on the low speed side. 1 inverter (G,), this first
A second inverter (G2) inverts the output logic of the inverter (Gl), and the output of the second inverter (G2) is “H”.
" level and when the steering type selection switch (20) is switched to the four-wheel steering type side, the neutral voltage (
The voltage whose polarity is inverted with respect to Vn) is set as the target voltage (Vb
), a second AND gate (G, ) that turns on only the second analog switch (G2) input to the rear wheel control valve drive circuit (23), and the first inverter (
G1) is at the "H" level and the steering type selection switch (20) is switched to the four-wheel steering type side, the neutral voltage (Vn
) as the target voltage (Vb) and inputs the third analog switch (G3) to the rear wheel control valve drive circuit (23).
A second AND gate (G4) is provided.

In other words, the steering type selection switch (20)
When the sub-shift lever (12) is switched to the low speed side while the auxiliary gear shift lever (12) is switched to the 4-wheel steering type side, only the second analog switch (G2) is turned ON, and the output of the inverting amplifier (80) is turned ON. The target voltage (Vb) is input to the rear wheel control valve drive circuit (23), resulting in a four-wheel steering system.Meanwhile, as the sub-shift lever (12) is switched to the high speed side, Only the third analog switch (G3) is turned on, and the
1-Tralumi pressure (Vn) is the rear wheel control valve drive circuit (
23) as a target voltage (Vb), and the rear wheel (3
) is maintained in a neutral steering state, resulting in a two-wheel steering system in which only the front wheels (2) are operated.

[Another example]

In the above embodiment, the configuration is such that the parallel steering type and the four-wheel steering type can be selectively used both during on-board operation and remote control, and the four-wheel steering type and the two-wheel steering type are used only during the on-board operation. Although a case has been exemplified in which the system is configured to be automatically switched in conjunction with the height change of the sub-transmission device, the two-wheel steering type may be selectively used regardless of the height change of the sub-transmission device. Further, the specific configuration of each part of the working vehicle can be changed in various ways depending on the form and purpose of use of the working vehicle to which the present invention is applied, and the present invention is not limited to the above embodiments. .

[Brief explanation of drawings]

The drawings show an embodiment of the steering control device for a working vehicle according to the present invention, FIG. 1 is a circuit diagram showing a specific configuration of the steering type switching means, FIG. 2 is a block diagram showing the overall configuration of the control system, and FIG. Figure 3 is an overall side view of the work vehicle. (2), (3)... Front and rear wheels, (8)...
...Main transmission, (13)...Sub-transmission,
(21)...Sub-shift position detection means, (100)
...Steering type switching means.

Claims (1)

[Claims] Both the front and rear wheels (2) and (3) can be operated with power steering, and a main transmission (
8) and an auxiliary transmission (13), the steering control device includes an auxiliary transmission position detection means (21) for detecting a switching position of the auxiliary transmission (13),
When the auxiliary transmission (13) is switched to the high speed side, a two-wheel steering operation is performed in which only the front wheels (2) are steered, and the auxiliary transmission (13) is switched to the low speed side. When switched, the front and rear wheels (2) and (3)
), the steering type switching means (100) automatically switches the steering type based on the detection information by the sub-shift position detection means (21). Steering control device for the installed work vehicle.