JPH0662091B2 - Power steering device for work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides means for detecting an actual steering angle of a steerable wheel whose direction can be freely changed and means for instructing a target steering angle. Power steering of a work vehicle provided with steering control means for automatically operating a steering actuator for changing the direction of the steering wheel based on information from both means so that the steering angle approaches the target steering angle. Regarding the device.

[Conventional technology]

In such a work vehicle, when the target steering angle is designated, the steering actuator is operated so that the actual steering angle detected by the sensor provided on the vehicle body side corresponds to the target steering angle. Let them do it.

[Problems to be solved by the invention]

When such a working vehicle is used on a sloping ground, if the vehicle makes a sharp turn despite being on a steep slope, a large centrifugal force acts on the vehicle body, which may cause the vehicle body to fall over. And the danger becomes remarkable when a sharp turn is made when traveling down a slope.

The present invention has been made in view of the above circumstances, and an object thereof is to avoid the risk of tipping over when turning a vehicle body on a sloping ground.

[Means for solving problems]

According to a characteristic configuration of the present invention, a vehicle body inclination detecting means for detecting the inclination of the vehicle body is provided, and the maximum steerable steering angle is smaller when the vehicle body inclination is larger than when the vehicle body inclination is smaller. The maximum steering angle changing means for automatically changing the maximum steerable steering angle based on the information of the vehicle body inclination detecting means is provided, and the operation and effect thereof are as follows.

[Action]

That is, based on the vehicle body inclination detection information by the vehicle body inclination detecting means, the maximum steerable steering angle is automatically changed so that the vehicle body inclination becomes smaller than the vehicle body inclination becomes smaller. (Refer to FIG. 1) Further, as compared with a structure in which the steering operation force becomes larger as the steering angle becomes larger, in this structure, even if the steering operation force becomes large, the steering is further turned off. Since it is possible to operate the angle large alligator, there is no possibility that the vehicle body will fall due to steering on a sloping ground, and the risk of falling does not disappear, but in the present invention, the maximum steering angle itself is Since the vehicle body is regulated so as to prevent the vehicle body from tipping over, when the traveling place is a steep slope, the vehicle cannot fall down suddenly.

〔The invention's effect〕

Therefore, since the maximum steerable steering angle can be changed according to the inclination of the vehicle body, the vehicle body falls over when the vehicle body turns on a sloping ground, and particularly when the vehicle travels down a sloping ground. This makes it possible to avoid the problem that the vehicle body falls over when running on a sloping ground.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 4 and 5, the seat (2), the handle (H), and the transmission (M) are provided on the rear side of the body frame (1) below the vehicle body (V), and on the front side. An engine (E) is provided respectively, front and rear steering wheels (3F), (3R) are provided at the lower part of the machine body frame (1), and a disc type cutting blade is provided at an intermediate portion between the front and rear wheels (3F), (3R). A lawn mowing device (4) having an interior is suspended so that it can move up and down, and thus a four-wheel drive lawnmower working vehicle is configured.

A scanning sensor (5) for detecting the boundary (L) between the unprocessed work site (B) and the already processed work site (C) at the tip of the frame (6) fixed to the lawnmower (4). When the work vehicle is automatically controlled as will be described later, the lawnmower (4) is set to the unprocessed work site (B) and the unprocessed work site based on the detection information of the scanning sensor (5). The steering control is performed so as to move along the boundary (L) with (C). The scanning sensors (5) are provided on both lateral side portions and front and rear side portions of the vehicle body, and these sensors (5) are used to position the vehicle body (V) with respect to the traveling direction of the vehicle body and the boundary (L). It is configured so that it can be selectively used by.

A driven wheel (7A) that rotates with the traveling of the vehicle body (V) is provided at the rear part of the vehicle body (V), and a distance sensor (7) that generates a pulse signal each time the driven wheel (7A) rotates by a predetermined angle. Is provided, and the traveling distance can be detected based on the pulse signal. Further, on the upper part of the vehicle body, there is provided a geomagnetic sensor type azimuth sensor (8) for detecting the traveling direction (azimuth) of the vehicle body (V) by sensing a change in the intensity of the geomagnetism.

As shown in FIG. 3, the output of the engine (E) is transmitted to a hydraulic continuously variable transmission (9) for traveling speed change provided in the transmission section (M). The transmission (9) is manually operated by a speed change pedal (not shown), and
At the time of remote control or automatic control, gear shifting operation is performed by a motor with reduction gear (10) as a traveling gear shifting actuator. The output of the transmission (9) is the differentials (3a) and (3b) of the front and rear wheels (3F) and (3R).
And to the lawn mower (4),
Therefore, the front and rear wheels (3F), (3R) and the lawnmower (4) are configured to be simultaneously driven.

The gear shift operation position of the motor (10) is detected by a potentiometer (R ₃ ) that is interlocked with the rotation of the gear shift operation shaft (11) of the gear shift device (9), and the detection information is fed back to the control device (12). I am doing it.

Both the front wheels (3F) and the rear wheels (3R) are configured to be steerable, and the front and rear wheels (3F) and (3R) are steered in the same direction to operate the vehicle body (V). Parallel steering type that moves in parallel without changing the direction of the front and rear wheels (3F), (3
One of a turning steering type in which R) is steered in a relatively opposite direction to turn with a small turning radius and a normal two-wheel steering type in which only the front wheels (3F) are steered like a car will be described later. It is configured so that it can be selected as follows.

The steering operation of the front and rear wheels (3F), (3R) is
This is done by so-called power steering operation.

That is, as shown in FIG. 3, a pair of front and rear double-acting hydraulic cylinders (13F) and (13R) are provided so as to be movable in the lateral direction of the vehicle body (V), and the cylinders (13F) and (13R ) Each of the front and rear wheels (3F), (3R) through the steering tie rods (14).
It is connected to each separately. Then, the hydraulic cylinder (1
3F) and (13R) are separately provided with a pair of electromagnetic valves (15F) and (15R), respectively, and a microcomputer (17) is provided for a target steering angle indicated by the handle (H) or automatic control.
And a target steering angle instructed by remote control, which will be described later, and a potentiometer (R) as an actual steering angle angle detecting means provided in each of the front and rear wheels (3F) and (3R). ₁ ) and (R ₂ ) so that the detected values match,
The electromagnetic valves (15F) and (15R) are connected to the control device (1
It is configured to be driven by the command of 2).

To construct the scanning sensor (5), two so-called photo interrupter type optical sensors (S) and (S), which are arranged in a state where a light emitting element and a light receiving element face each other, are attached to a vehicle body (V). It is fixed to the front end of a frame (6) whose base end is fixed to the lawnmower (4) so as to be lined up in the left-right direction. Then, by detecting the presence or absence of turf passing between the light emitting element and the light receiving element, it is possible to detect whether the grass is located on the unprocessed work site (B) or the processed work site (C). Therefore, the optical sensor (S) on the outer side of the vehicle body (V) detects the processed work site (C), and the optical sensor (S) on the inner side of the vehicle body (V) detects the unprocessed work site (B). The positional relationship between the boundary (L) and the vehicle body (V) in the left-right direction is determined by regarding the operating state as the state along the boundary (L). In addition, the detection information of the scanning sensor (5) is that the left and right scanning sensors (5), (5) on the front side in the traveling direction detect the processed work site (C), and the traveling distance detected by the distance sensor (7). Reaches the reference distance of one stroke set in advance,
It is also used as a control parameter for activating the direction change control for moving to the next stroke after the traveling of one stroke is completed.

Further, the work site condition detection signal obtained from the optical sensor (S) having the above-mentioned configuration becomes a discontinuous pulse-shaped signal due to the grass passing intermittently, and therefore, as shown in FIG. The waveform processing circuit (16) is configured to be integrated and then input to the control device (12). The integration time constant of the waveform processing circuit (16) is set by the output pulse signal from the distance sensor (7) so as to automatically become the optimum value corresponding to the traveling speed. By performing all the processing digitally, it is configured to function as a digital filter.

Hereinafter, the configuration of the control device (12) will be described based on the circuit diagram shown in FIG.

The output pulse signal from the distance sensor (7) is sent via the CTC to the microcomputer (17) (hereinafter, CPU).
(Abbreviated as (17)) and generates an interrupt signal for each unit traveled distance, so that the waveform processing circuit (1
6) output from the optical sensor (S) ... to the work site situation determination signal by the I / O port (18) (hereinafter, input P
IO (18) will be taken in and arithmetic processing will be performed to determine which of the vehicle body (V) with respect to the boundary (L), and a control signal for steering the front and rear wheels (3F), (3R) is output. The output is made from the PIO (24).

Manual operation in which the vehicle is operated by manual operation, and traveling around the outer periphery of the planned work area in advance by manual operation before performing automatic travel control, thereby setting the surroundings as the processed work site (C), and the travel distance and the azimuth between them. Sensor (8)
The control device (12) is operated in either of a teaching mode in which the work range is taught by sampling the detected azimuth according to the above, and a reproduction mode in which the work site is automatically traveled in a predetermined range set by the teaching mode. The signal from the operation mode selection switch (SW ₃ ) for selecting whether or not and the signal from the start switch (SW ₄ ) for instructing the start of the operation in the reproduction mode are also sent to the CPU via the input side PIO (18).
The input is made in (17).

The output signal of the direction sensor (8) is a bandpass filter (1
9) and a buffer (A ₀ ) are input to a multiplexer (20) together with signals from the potentiometers (R ₀ ) to (R ₃ ) and digitized by an A / D converter (21) to It is input to the CPU (17).

A pilot type selection switch (SW ₂ ) is provided to select between a manual operation mode in which the operator rides on the vehicle body to operate and a remote control (radio control) mode in which the pilot remotely operates from outside the aircraft.
Then, in the manual operation mode, the parallel steering,
A steering type selection switch (SW ₁ ) for selecting the steering type of turning steering or two-wheel steering is provided, and a transmitter (22a) and a receiver (2) for remote control are provided.
Each of 2b) is provided.

The receiver (22b) is a first for steering type selection.
Each of the channels (CH ₁ ), the second steering operation channel (CH ₂ ), and the shift operation channel (CH ₃ ) is provided, and signals from these channels (CH _{1 to} CH ₃ ) are supplied to the F / V converter (23 ), Each converted into a voltage signal, and each of the converted signals is input via the analog switch (G ₀ ) only when the remote control switch (SW ₂ ) is turned on. ing. The signal from the CPU (17) is I / O.
It is output to the 3-state buffer (G ₁ ) via a port (hereinafter, abbreviated as output PIO).

The 3-state buffer (G ₁ ) is used for the front and rear wheel electromagnetic valve drive circuits (26F), (26R) and the drive circuit (27) for the speed change motor (10) in the manual mode or the remote control mode. This is for switching between the state in which the control signal is output and the state in which the control signal is output in the reproduction mode during automatic control. Further, (25) in FIG. 2 is a control solenoid valve for an actuator (not shown) for switching to the differential lock state in which the operation of the rear wheel differential device (36) is blocked.

As shown in FIG. 5, an inclination detection sensor (D) is provided as vehicle body inclination detection means for detecting the inclination of the vehicle body (V). That is, the weight (28) is suspended and supported so as to be swingable around the longitudinal axis of the vehicle body, and a potentiometer (R ₄ ) for detecting the swing position of the weight (28) is provided.
It is configured to detect the inclination of the vehicle body in the left-right direction.

Then, based on the detection information of the tilt detection sensor (D), the maximum operable steering angle is automatically changed as follows.

The maximum steering angle changing means will be described below with reference to FIG. In the following, the right maximum value of the target steering angle (θ) is + 40 °, the left maximum value is −40 °, and the output voltage (E) from the F / V converter (23) is An example will be described in which the target steering angle (θ) changes to 0 to 12 V (see FIG. 6).

A pair of first comparators (29a), (29b) for judging whether the tilt detection value in the left-right direction of the vehicle body (V) by the potentiometer (R ₄ ) in the tilt detection sensor (D) is larger or smaller than a set value. The target steering angle (θ) instructed by the transmitter (11a), that is, F
The steering angle instruction voltage (E) output from the / V converter (23) is a set voltage (for example, 9 V or 3).
A pair of second comparators (31a) and (31b) for discriminating whether it is larger or smaller than V) is provided, and a difference between the instruction voltage (E) and the set voltage (for example, 9V or 3V) is calculated and output. A pair of first operational amplifiers (30a), (30
b) is provided, and the second comparators (31a), (31
b) output signal from the first comparator (29
a) and the signal output from the OR circuit (35) connected to (29b), and two AND circuits (34a) and (3
4b). Then, the analog switches (33a) and (33b) which are always returned to the ground side are
Output signals from the first operational amplifiers (30a) and (30b) are output from the AND circuits (34a) and (34b), respectively, and the output signals from the first operational amplifiers (30a) and (30b) are inverted or non-inverted to the second operational amplifier (32). The vehicle body inclination is set to be equal to or greater than a set value and the target steering angle (θ) is set to be greater than or equal to the set angle (20 °) in either the left or right direction of the vehicle body (V). In this case, the output voltage from the first operational amplifier (30a), (30b)
The maximum steering angle is changed by outputting to the operational amplifier (32) and adding or subtracting the output voltage to the voltage (E) corresponding to the target steering angle (θ).

That is, as shown in FIG. 6, the target steering angle (θ) instructed by the transmitter (22a) exceeds a predetermined angle range (for example, −20 ° <θ <20 °), and the inclination sensor (θ). Only when the angle detected by the potentiometer (R ₄ ) in D) exceeds the set angle, the voltage (E) corresponding to the target steering angle (θ) is gradually increased or decreased as indicated by the chain double-dashed line. Therefore, the maximum steerable steering angle is limited. In addition, (N) in the figure is a neutral angle corresponding to straight ahead.

Incidentally, in FIG. 2, (A ₃ ) is a differential amplifier,
(A ₁ ) is a comparator for comparing the output voltage from the differential amplifier (A ₃ ) with a reference voltage. Further, (F) in the figure is a solenoid valve for diff lock control when the steering type is a parallel steering type, or when the front wheel (3F) is near the neutral position (N) in the turning steering type and the two-wheel steering type. It is a circuit for activating (25) so as to be in an ON state.

[Another embodiment]

In the above embodiment, to change the maximum steering angle,
Although the target steering angle (θ) is changed by operating the transmitter (11a), the potentiometer (R
_The detected steering angle may be changed according to ₁ ) and (R ₂ ).

In the above embodiment, the target steering angle (θ) is changed only in the remote control mode, but it may be changed in the manual operation mode or the automatic control.

Further, in the above-mentioned embodiment, when the maximum steering angle is changed, the target steering angle (θ) is gradually increased or decreased when the value exceeds the set value, but as shown in FIG. The voltage (E) with respect to the target steering angle (θ) in value may be kept constant and the change of the target steering angle (θ) may be stopped. In the figure, the set angle is -30
It is set at 30 and 30 degrees.

The vehicle body inclination detecting means (D) of the above-described embodiment detects the inclination of the vehicle body (V) in the left-right direction, and detects both the front-back direction and the left-right direction of the vehicle body (V), whichever is larger. The inclination may be the inclination of the vehicle body (V). An example will be described for that purpose, as shown in FIG. 8, a weight (41) is hung and supported so as to be swingable in the front-rear direction and the left-right direction of a vehicle body, and is inserted into a support rod (42) supporting the weight (41). U-shaped plate bodies (43a) and (43b) having long holes
Each of them is provided in a state of oscillating about a perpendicular axis, and potentiometers (40a) and (40b) for detecting the rotation angles of the plate bodies (43a) and (43b) are provided. Plates (43a), (43b) accompanying the swing
Rotate, and the rotation angle is adjusted by the potentiometer (40
It is detected by a) and (40b), and the larger detected value of the detected values is set as the inclination of the vehicle body (V).

The power steering device of the present invention is, in addition to a lawnmower,
It can be applied to various work vehicles such as transport vehicles.

[Brief description of drawings]

1 is a block diagram showing the configuration of the present invention, FIG. 2 is a circuit diagram showing the configuration of a control device, and FIG. 3 is a control system. FIG. 4 is a plan view of the lawnmower vehicle, FIG. 5 is a side view thereof, and FIG. 6 is a graph showing the relationship between the target steering angle and the voltage. FIG. 7 is a graph showing another embodiment of the relationship between the target steering angle and the voltage, and FIG. 8 is a perspective view showing another embodiment of the vehicle body tilt detection sensor. (3F), (3R) ... Steering wheels, (13F), (13
R) ... Steering actuator, (D) ... Vehicle tilt detection means.

Continuation of the front page (56) References JP-A-60-67275 (JP, A) JP-A-49-118126 (JP, A) JP-A-56-95768 (JP, A) JP-A-46-5263 (JP , A) JP 52-77329 (JP, A) JP 59-227567 (JP, A) JP 59-146311 (JP, A) JP 61-108064 (JP, A) 61-127079 (JP, U)

Claims (3)

[Claims] 1. Steering wheels (3F), (3) whose directions can be freely changed.
R) means for detecting the actual steering angle, and
Steering actuators (13F) and (13R) for changing the steering wheels (3F) and (3R) so as to bring the actual steering angle closer to the target steering angle. ) Is a power steering device for a working vehicle, which is provided with a steering control means for automatically operating based on the information of the both means, the vehicle body tilt detecting means (D) for detecting the tilt of the vehicle body is provided, and the operation is performed. The maximum steerable steering angle is automatically set based on the information of the vehicle body inclination detecting means (D) so that the maximum possible steering angle is smaller when the vehicle body inclination is larger than when it is smaller. A power steering device for a work vehicle, which is provided with means for changing the maximum steering angle. 2. The power steering apparatus for a work vehicle according to claim 1, wherein the maximum steering angle changing means is means for changing the target steering angle based on the vehicle body tilt detection information. 3. A power steering apparatus for a work vehicle according to claim 1 or 2, wherein the vehicle body inclination detecting means (D) is means for detecting an inclination of the vehicle body in the front-rear direction.