JPH0618482B2 - Lifting control device for work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention aims at a working device based on height detection means for detecting a height above ground of the working device and detection information of the height detection means. In order to maintain the height, a lifting control means for operating the lifting actuator of the working device is provided, and the height detection means is a transmitter that periodically transmits an ultrasonic wave toward the ground, A receiver that outputs a reception signal having a level corresponding to the intensity of reflected ultrasonic waves, a reception detection unit that detects the reception time based on the level of the reception signal being a set value or more, and the time when the ultrasonic wave is transmitted. From the measuring means for measuring the time from the reception of the ultrasonic wave,
The present invention relates to a lift control device for a work vehicle, wherein the transmitter and the receiver are attached to the work device so as to move up and down as the work device moves up and down.

[Conventional technology]

Such a work vehicle lift control device detects the time from the transmission of ultrasonic waves to the reception of ultrasonic waves as the ground height of the work device, and based on the detection result, maintains the work device at the target height. It is designed to be controlled to move up and down.

Incidentally, the reception time is detected based on the level of the received signal being equal to or higher than the set value as described above. At that time, the set value is generally changed automatically. ing. That is, since the level of the received signal is attenuated in inverse proportion to the square of the distance (height) to the ground, means for gradually lowering the set value with the passage of time from the time of reception has been conventionally used. Has been. (See, for example, JP-A-59-68685).

Further, in place of the above means, the applicant of the present invention lowers the set value to a value lower than the current value when the reception detecting means does not detect the reception of reflected ultrasonic waves, and Has previously proposed a means for resetting a set value in accordance with the measured distance upon detection of reception of the. (See Japanese Patent Application No. 62-10743).

By the way, in the past, even if the time measured with the current ultrasonic wave transmission was significantly larger than the time measured with the previous ultrasonic wave transmission, the work device was immediately lowered based on the current measured time. I was trying to let it. (See Japanese Patent Application No. 62-10743 mentioned above).

[Problems to be solved by the invention]

As shown in FIG. 8, the ground has a recess (U), and when detecting the height with respect to the location where such a recess (U) exists, the recess (U) is erroneously detected. There is a disadvantage that the working device is unnecessarily lowered by detecting the height with respect to the bottom surface of).

In other words, the reception level of reflected ultrasonic waves from the ground surface
Due to (U), it becomes smaller than the set value, while the concave (U)
The reception level of the reflected ultrasonic waves from the bottom surface of the recess may become higher than the set value, and as a result, the height of the recess (U) relative to the bottom may be erroneously detected.

Then, as a result of unnecessary lowering of the work device due to the erroneous detection, not only the work device cannot be maintained at a desired target height, but also the work device may be deformed and damaged due to collision with the ground. there were. By the way, this trouble becomes noticeable when the target height is set low.

The present invention has been made in view of the above situation, and an object thereof is to suppress the occurrence of troubles due to erroneous detection of height detecting means.

[Means for solving problems]

The characteristic configuration of the work vehicle lift control device according to the present invention is a measurement for detecting that the time measured with this ultrasonic transmission is greater than the time measured with the previous ultrasonic transmission by a set time or more. The time monitoring means is provided, and the safety means that operates based on the detection information of the measurement time monitoring means is provided, and the action and effect thereof are as follows.

[Action]

That is, when the measurement time monitoring unit detects that the time measured with the current ultrasonic transmission is longer than the time measured with the previous ultrasonic transmission by the set time or more, for example, The safety means is operated such as stopping the lifting control based on the measurement time to prevent the working device from being lowered unnecessarily.

〔The invention's effect〕

Therefore, it is possible to suppress the work device from unnecessarily lowering due to an erroneous detection caused by the concave portion existing on the ground.

〔Example〕

Hereinafter, the case where the embodiment of the present invention is applied to the elevation control of the combine harvester will be described.

As shown in FIG. 2, the combine is a crawler traveling device.
(1) is provided with a traveling vehicle body (W), and a mowing section (2) which is connected to a front portion of the vehicle body so as to be able to move up and down, and the mowing section (2) is a single-acting hydraulic cylinder (3 ).

Height detecting means for detecting the height of the reaper (2) above the ground is provided. As shown in FIG. 1, the height detecting means is so arranged that it moves up and down as the cutting unit (2) moves up and down.
The sensor main body (4) attached to the main body and a control device (H) using a microcomputer are mainly configured.

The sensor body (4) receives the reflected ultrasonic waves from the ground and the transmitter (4a) that transmits the ultrasonic waves toward the ground intermittently at a set cycle (for example, 50 mS), and the intensity of the reflected ultrasonic waves. And a receiver (4b) that outputs a reception signal (P) of a level according to the.

The control device (H) gives a transmission command to the transmitter (4a) at a set cycle, and from the time of transmitting the ultrasonic wave, the level of the reception signal (P) of the receiver (4b) is a set value. It is configured to measure the time until reception at (Vn) or more as the ground height.

That is, the control device (H) is provided with a reception detection means (100) for detecting the reception time based on the level of the reception signal (P) of the receiver (4b) being equal to or higher than a set value. ,
Using the control device (H), a measuring means (101) is configured to measure the time from the time of transmitting the ultrasonic wave to the time of receiving the ultrasonic wave.

The reception detecting means (100) is a comparator (K) for comparing the set value (Vn) set by the set value setting means (105) with the level of the received signal (P), and an oscillator (4a ), A flip-flop (F) that is set by the output signal of the comparator (K).

By the way, the set value setting means (105) is a plurality of resistors (R) connected between the power supply and the ground point, and a plurality of diodes for switching each connection point between adjacent resistors to the ground state ( Do) and, by selecting which one of the ground points is switched to the grounded state,
As shown in the figure, the set value (Vn) can be changed in 6 steps (V _{1 to} V ₆ ).

However, when ultrasonic waves are transmitted from the transmitter (4a), there is a possibility that some ultrasonic waves will be directly received by the receiver (4b). Therefore, after transmitting ultrasonic waves from the transmitter (4a),
Keep the maximum setting value (V ₆ ) until (1ms) elapses.
After that, the target set value (Vn) instructed at the present time is maintained. That is, of the 6-stage setting values (V _{1 to} V ₆ ), the maximum setting value (V ₆ ) is used to prevent direct waves of ultrasonic waves from being received, and the remaining 5 setting values (V ₆ V ₁
~ V ₅ ) will be used for detection on reception. Then, the maximum value (V ₅ ) of the set values (V _{1 to} V ₅ ) in 5 steps is set to a voltage higher than the maximum value (saturation voltage value) of the level of the reception signal (P) of the receiver (4b). Is set to.

The instruction of the target setting value (Vn) will be described later.

The measuring means (101) measures the time from when the ultrasonic wave is emitted until the flip-flop (F) is set, and stores the measured time.

By the way, the time until the flip-flop (F) is set, and the storage process that accompanies it is performed as so-called interrupt processing while inputting the output signal as the flip-flop (F) is set as an interrupt signal. It is done.

By the way, the control device (H) maintains the mowing unit (2) at a target height (also referred to as a target mowing height),
It also functions as an ascending / descending control means (102) for ascending / descending the cutting unit (2) based on the detection information of the height detection means.

That is, the information of the target height setting device (5) that can be manually adjusted is input to the control device (H), so that the measured height above ground is maintained at the target height.
The control device (H) gives an operation command to the control valve (6) of (3).

However, (7) in FIG. 1 is a switch for instructing the control device (H) whether or not to perform the lifting control.

In addition, using the control device (H), a measuring time monitoring means (10
3) and safety means (104) that operates based on the detection information of the means (103) are configured.

The measurement time monitoring means (103) is configured such that the time (D _t ) measured with the current ultrasonic transmission is a set time (α) rather than the time (D _t-1 ) measured with the previous ultrasonic transmission. It is to detect that it is larger than the above.

Further, the safety means (104) is configured to replace the previous measurement time (D _t-1 ) with the current measurement time (D _t ).

Therefore, if the current measurement time (D _t ) is longer than the previous measurement time (D _t-1 ) by the set time (α) or more due to the presence of a recess in the ground, Since the ascending / descending control is performed based on (D _t-1 ), unnecessary descending is not performed.

However, if the current measurement time (D _t ) is longer than the previous measurement time (D _t-1 ), if the set number of times (β) continues (for example, 5 times), the safety means (104) is activated. Instead, the ascending / descending control is performed based on the measured time (D _t ) of this time.

Next, while explaining the operation of the control device (H), various means will be described.

As shown in FIG. 3, when the control device (H) is activated, it first executes initialization processing, and then checks the time for executing the control program described below every 1 ms.

After that, the operating state of the switch (7) is checked. Then, when it is in the ON state, the time for transmitting ultrasonic waves is checked every 50 ms, and the processing for transmitting ultrasonic waves is executed if necessary. By the way, the process of resetting the flip-flop (F) is also programmed in this transmission process.

Next, only during the set time (1 ms) after the call is made, the set value (Vn) for detection at reception is set to the maximum (V ₆ ), and then, the set value (Vn) of the target currently instructed is maintained. Execute the set value setting process.

Next, after the ultrasonic wave is transmitted, when 6 ms elapses beyond the maximum measurement time, the ground height determination process and the set value change process that determines the target set value (Vn) in the receiving time detection means (100) are executed. To do. It should be noted that these processes are programmed to be executed only once for each transmission.

After that, an output process is performed in which the control valve (6) is operated based on the determination result of the ground height.

The ground height determination processing will be further described. First, as shown in FIG. 4, it is checked whether or not the signal is received based on the output signal of the flip-flop (F). This measurement time (D _t ) and the previous measurement time (D _t
Check whether the difference with _t-1 ) is more than the set value (α) or not.

If it is not equal to or larger than the set value (α), the count value (M) of the abnormality counter is reset to zero, and then the current measurement time (D _t ) is substituted as the measurement value (D).

On the other hand, if it is equal to or greater than the set value (α), whether the count value (M) is larger than the set value (β) after the count value (M) of the abnormality counting counter is added Check. And if it is not large, the measured value of this time
As (D), the process of substituting the previous measurement time (D _t-1 ) is executed, while if it is large, the process of resetting the count value (M) to zero and the measurement value (D ), The process of substituting the measurement time (D _t ) of this time is executed.

In addition, in the above-mentioned check, when it is determined that it has not been received, the previous measurement value (D _t-1 ) is set as the measurement value (D).
Execute the process of substituting.

To explain the output process further, as shown in FIG. 6, first, it is checked whether or not the measured value (D) is within the target range obtained by adding the tolerance to the target value. , The operation of the control valve (6) is stopped, and the process of stopping the elevation is executed.

If the measured value (D) is not within the target range, it is checked whether the measured value (D) is larger than the target value. If it is large, the control valve (V) is used to lower the mowing part (2).
Is performed, and if it is not large, a raising process for activating the control valve (6) to raise the reaper (2) is performed.

In the setting value changing process, basically, when the reflected ultrasonic waves are not received, the setting value (Vn) is lowered to a value (Vn-1) lower than the current value by one step. Then, when it is received, the set value (Vn) is changed and set according to the measurement time (D _t ). When changing and setting, the measurement time (D _t ) is divided into 5 stages according to the set values (V _{1 to} V ₅ ) of 5 stages, and is suitable for the measurement time (D _t ) of this time. While determining the set value (Vn), the setting is changed based on the determination result.

To add a description based on the flowchart of FIG. 5, first, it is checked whether or not the signal is being received based on the output signal of the flip-flop (F).

Then, if received, the discrimination data (R ₂ ) is set to any of 5 levels (V _{1 to} V ₅ ) based on the measurement time (D _t ) and then the setting data (R It is checked whether ₁ ) matches the discrimination data (R ₂ ).

If they match, the set value (Vn) is set based on the current set data (R ₁ ).

On the other hand, if they do not match, a process of adding the count value (S) of the mismatch count counter is executed, and then it is determined whether or not the count value (S) has reached the set value (γ) (for example, 5). To check.

If it has not reached, the current setting data (R
Based on ₁ ), the process of setting the set value (Vn) is executed.
On the other hand, if reached, after resetting the count value (S) to zero, by substituting the sets of identification data (R ₂₎ data (R _1), the setting data after the assignment (R ₁₎ Based on the set value
Set (Vn).

In addition, in the above-mentioned check, when it is determined that the setting data (R ₁ ) is not received, the processing corresponding to the setting data (R ₁ ) at the present time is lowered by one step, and the setting data (R
Set the set value (Vn) based on ₁ ).

[Another embodiment]

INDUSTRIAL APPLICABILITY The present invention can be applied not only to the lifting control of the harvesting section (2) of the combine, but also to the lifting control of the working device of various work vehicles.

As the safety means (104), any means can be used as long as it is useful for suppressing unnecessary lowering of the working device (2), and means for stopping the lifting control, an alarm means, or the like can be applied. In the case of the alarm means, the operator performs an operation such as stopping the lifting control.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

The drawings show an embodiment of an operator lifting / lowering control device according to the present invention. FIG. 1 is a schematic view showing a control configuration, FIG. 2 is a side view of a combine front portion, and FIGS. 3 to 6 are control operations. FIG. 7 is a diagram showing the relationship between the received signal and the set value, and FIG. 8 is a schematic diagram of the detection state of the location where the recess is present. (2) …… Working device, (3) …… Lift actuator, (4a)
...... Transmitter, (4b) …… Receiver, (100) …… Reception detection means, (101) …… Measurement means, (102) …… Elevation control means, (10
3) …… Measuring time monitoring means, (104) …… Safety means, (P) ……
Received signal, (Vn) ... Set value.

Claims (4)

[Claims] 1. A height detecting means for detecting a height of the working device (2) above ground, and the working device (2) is maintained at a target height based on detection information of the height detecting means. In order to
Elevating control means (102) for operating the elevating actuator (3) of the working device (2) is provided, and the height detecting means is a transmitter (4a) that periodically emits ultrasonic waves toward the ground.
And a receiver (4b) that outputs a reception signal (P) at a level corresponding to the intensity of reflected ultrasonic waves, and when receiving based on the level of the reception signal (P) being a set value (Vn) or more. The detection means (100) for detecting the, and the measuring means (101) for measuring the time from the time of transmitting the ultrasonic wave to the time of receiving the ultrasonic wave, the transmitter (4a) and the receiver ( 4b), so that the working device (2) so as to move up and down with the lifting of the working device (2)
It is an elevator control device for a work vehicle that is attached to and detects that the time measured with this ultrasonic transmission is longer than the time measured with the previous ultrasonic transmission by a set time or more. An elevator control device for a work vehicle, which is provided with a measurement time monitoring means (103) and is provided with a safety means (104) which operates based on detection information of the measurement time monitoring means (103). 2. The lift control device for a work vehicle according to claim 1, wherein the safety means (104) is a means for replacing the previously measured time with the currently measured time. 3. The lift control device for a work vehicle according to claim 1, wherein the safety means (104) is means for stopping the lift control based on the current measurement time. 4. The lift control device for a work vehicle according to claim 1, wherein the safety means (104) is an alarm means.