JP2000050705A - Working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly operate a hydraulic cylinder without delay in control by sending a proper electric current to an electromagnetic solenoid of a control valve of electromagnetic proportional type. SOLUTION: In the lifting and lowering control of a rotary tilling apparatus, an electric current value Ir sent to the electromagnetic solenoid of a control valve for controlling a lift cylinder is measured. When the electric current value Ir is different from a target electric current value Io set based on the deviation of lifting and lowering control, a correction value C for correcting a driving signal is set. After the setting, a control mode is set so as to correct the driving signal by the correction value C and to output the electromagnetic solenoid and the correction value C is renewed at each set interval.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention includes a hydraulic drive system for supplying hydraulic oil from a hydraulic pump driven by an engine to a hydraulic actuator via an electromagnetic proportional control valve, and also sets an operation target of the hydraulic actuator. A control device to which a setting signal from a setting device to be set and a detection signal from a sensor for detecting an operation position of the hydraulic actuator are input;
And a power control means for supplying a current from a power supply to the electromagnetic solenoid of the control valve based on a drive signal from the control device, and a deviation between a setting signal from the setting device and a detection signal from the sensor. A work vehicle in which a control mode of the control device is set such that a target current value is set based on the target current value, and a drive signal set corresponding to the target current value is sent to the power control means.

[0002]

2. Description of the Related Art Conventionally, there is a work vehicle constructed as described above as disclosed in Japanese Patent Application Laid-Open No. 5-66802. In this conventional example, an electromagnetic proportional flow control is applied to a lifting and lowering control system of an agricultural tractor. Equipped with a type (electromagnetic proportional type) control valve,
At the time of position control, a current of a value for obtaining a target opening based on a deviation between a first potentiometer that sets the level of the tilling device with respect to the vehicle body and a second potentiometer that feedbacks the level of the cultivating device with respect to the vehicle body is used as a solenoid of the control valve. (Electromagnetic solenoid).
At the time of this supply, the deviation between the actual supply current actually flowing to the solenoid and the target current value is determined, and proportional integration control is performed.
The current value is adjusted until the actual supply current reaches the target current value.

[0003]

As in the above-mentioned prior art, a current actually flowing to an electromagnetic solenoid is measured, and the current value is corrected until the current value reaches a target current value. So, for example, when the voltage of the battery as a power supply is low, such as when starting work in cold regions,
It is necessary for the electromagnetic solenoid of the control valve even if an appropriate drive signal is sent to power control means such as a transistor, as in the case where the temperature of the electromagnetic solenoid changes during work and the electric resistance value of the electromagnetic solenoid changes. Even if the current is not supplied and the opening of the control valve does not reach the required value, by performing control to correct the target current value, the required current is supplied to the electromagnetic solenoid to perform the desired control. Can be easily performed. But,
In the case of performing feedback control every time a current is supplied to the electromagnetic solenoid as in this conventional example, not only leads to a control delay, but also a phenomenon in which only a small current flows at the beginning of a control requiring a large current, The opposite phenomenon may occur, and there is room for improvement in smoothing the operation of the hydraulic actuator. An object of the present invention is to rationally construct a work vehicle capable of smoothly operating a hydraulic actuator without causing a control delay while utilizing the effectiveness of control of supplying a required current to an electromagnetic solenoid. is there.

[0004]

According to a first feature of the present invention, as described at the outset, hydraulic oil from a hydraulic pump driven by an engine is supplied via an electromagnetic proportional control valve. A control device that includes a hydraulic drive system that supplies the hydraulic actuator, and receives a setting signal from a setting device that sets an operation target of the hydraulic actuator and a detection signal from a sensor that detects an operation position of the hydraulic actuator, and Power control means for supplying a current from a power supply to an electromagnetic solenoid of the control valve based on a drive signal from the control device, based on a deviation between a setting signal from the setting device and a detection signal from the sensor. Set the target current value,
In a work vehicle in which the control mode of the control device is set so as to send a drive signal set in accordance with the target current value to the power control means, a current value flowing through the electromagnetic solenoid of the control valve is measured. Measuring means, when there is a difference between the current value measured by the measuring means and the target current value, a correction value capable of compensating for the difference is set, and after setting the correction value, The control mode of the control device is set so as to correct the drive signal with the correction value. The operation and effect are as follows.

[0005] A second feature of the present invention (claim 2) is that in claim 1, a coefficient obtained by dividing the target current value by a current value measured by the measuring means is set as the correction value. At the same time, when controlling the hydraulic actuator, the control mode of the control device is set so as to correct the drive signal by multiplying the drive signal set corresponding to the target current value by a correction value. , Its operation and effect are as follows.

A third feature of the present invention (claim 3) resides in that in claim 1, the control mode of the control device is set so that the correction value is updated every set time. The effects are as follows.

A fourth feature of the present invention (claim 4) is that, in claim 1, the engine is operated by an on operation, electric power is supplied to an electric device of the vehicle body, and the engine is stopped by an off operation to stop the engine. A switch for stopping power supply to the electric device is provided, and the correction value is set only when the switch is in an ON state, and the correction value set by turning off the switch is erased. The operation and effect are as follows.

According to the first feature, when controlling the hydraulic actuator, the control means determines the target current value for the electromagnetic solenoid of the control valve based on the deviation between the setting signal from the setter and the signal from the sensor. Then, a drive signal corresponding to the target current value is sent to the power control means, and the current from the power supply is supplied from the power control means to the electromagnetic solenoid. When supplying this current, the measuring means measures the current value actually flowing to the electromagnetic solenoid, compares this current value with the target current value, and sets a correction value if there is a difference, If a value is set,
Thereafter, the current of the value corrected by this correction value is supplied to the electromagnetic solenoid, so that the current is temporarily supplied and then corrected as in the conventional example. An appropriate current value is supplied to the electromagnetic solenoid from the start of current supply, and the hydraulic actuator can be driven at a desired speed without greatly changing the current flowing through the electromagnetic solenoid.

According to the second feature, since the correction value is set in the form of a coefficient, a target current value is obtained in accordance with the deviation between the setter and the sensor, and only the calculation of multiplying the target current value by the correction value is performed. Thus, the above control can be performed by accurately obtaining the required current value.

According to the third feature, since the correction value is updated every set time, for example, when the electric resistance value of the electromagnetic solenoid is different from the assumed value due to the temperature,
As in the case where the voltage of the battery as the power supply is low, after the current value supplied to the electromagnetic solenoid is corrected at the beginning of the control, the temperature changes over time, or the battery voltage increases. Even if it is necessary to change the correction value, the correction value is updated every set time, so that the time wasted in the processing as in the case of performing the correction every time the current is supplied to the electromagnetic solenoid as in the conventional example. A current of an appropriate value can be supplied to the electromagnetic solenoid without consuming power.

According to the fourth feature, for example, when the temperature at the time of the operation before the switch is turned off and the temperature at the start of the operation after the switch is turned on are greatly different from each other, for example, Even when the correction value in the situation is greatly different and the difference in the operating speed of the hydraulic actuator is large, when the switch is turned off, the correction value is deleted, and the current value supplied to the electromagnetic solenoid is excessively large. Avoids the phenomenon of being too small and enables a reasonable operation.

[Effects of the Invention] Accordingly, a current of an appropriate value required for an electromagnetic solenoid is passed to avoid a delay in operation and a disadvantage that the hydraulic actuator operates at an excessively high speed at the start of control. The work vehicle capable of operating the vehicle is rationally configured (claim 1).
In addition, a current of a required value can be supplied to the electromagnetic solenoid by a simple calculation based on the correction value (claim 2). By updating the correction value every set time, control can be performed quickly without delay. Thus, when the engine is started and work is started, useless operation of the hydraulic actuator can be avoided and smooth operation can be performed (claim 3). Item 4).

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the rear part of an agricultural tractor as a working vehicle. A pair of left and right lift arms 2 which are moved up and down by the driving force of a lift cylinder 1 (an example of a hydraulic actuator) are provided at the rear of the body of the agricultural tractor.
And a rotary tilling device 5 is connected and supported via a three-point link mechanism including a single top link 3 and a pair of left and right lower links 4. The lower link 4 and the lift arm 2 are connected to a lift rod 6. The rotary tilling device 5 can be moved up and down by the driving force of the lift cylinder 1 by being suspended and supported by the lift cylinder 1. Also, the double-acting rolling cylinder 7 interposed in the right lift rod 6 can be expanded and contracted. The operation is such that the rolling operation of the rotary tillage device 5 can be performed.

As shown in FIG. 2, a hydraulic system for the lift cylinder 1 and the rolling cylinder 7 is formed. That is, the hydraulic oil from the hydraulic pump P driven by the engine E is diverted through the flow priority valve 10 and a fixed amount of control flow is supplied to the electromagnetically operated rolling control valve 11.
An oil passage system for supplying an excess flow from 0 to the electromagnetic proportional lift control valve V is configured. The rolling control valve 11 is configured to be switchable between a contracted position for contracting the rolling cylinder 7 based on an electric signal, an extended position for extended operation, and a neutral position for preventing extension and contraction. The lift control valve V includes a lift control valve 12 that supplies hydraulic oil to the lift cylinder 1, a lift pilot valve 12P that opens and closes the lift control valve 12 with pilot pressure, and hydraulic oil from the lift cylinder 1. And a lowering pilot valve 13P that opens and closes the lowering control valve with pilot pressure. The ascending pilot valve 12P and the lowering pilot valve 13P are each provided with an electromagnetic solenoid. The opening is changed in direct proportion to the current value supplied to 12S and 13S to change the pilot pressure, so that the opening of each of the ascending control valve 12 and the descending control valve 13 can be adjusted.

Since the rotary tilling apparatus 5 is lifted because of such a configuration, the lifting pilot valve 1 is used.
A current is supplied to the 2P electromagnetic solenoid 12S, and by adjusting the current value of this current, the ascending pilot valve 1S is increased.
The opening of 2P changes in direct proportion to the current value, and the pilot pressure acting on the rising control valve 12 from this rising pilot valve 12P changes to make the opening of the rising control valve 12 proportional to the current value. As a result, the hydraulic cylinder is supplied to the lift cylinder 1 in an amount proportional to the opening, and the ascent speed of the rotary tilling device 5 is determined. Similarly, when the rotary tilling apparatus 5 is lowered, a current is supplied to the electromagnetic solenoid 13S of the lowering pilot valve 13P, and the opening of the lowering pilot valve 13P is adjusted by adjusting the current value of the current. As a result, the pilot pressure acting on the descending control valve 13 changes from the descending pilot valve 13P and the opening of the descending control valve 13 is set to a value proportional to the current value. Hydraulic oil in an amount proportional to the opening is discharged from the lift cylinder 1, and the lowering speed of the rotary tilling device 5 is determined.

As shown in FIG. 3, a potentiometer type lever sensor 17S for measuring an operation position of a position lever 17 provided on the vehicle body to a control device 16 having a microprocessor, and a swing amount of the lift arm 2 are measured. Potentiometer type lift arm sensor 2S for measuring
And a potentiometer-type tillage setting device 18 operated by a dial 18 to set the tillage depth of the rotary tillage device 5.
The signal from the S and the potentiometer type cover sensor 5S which measures the swinging amount of the rear cover 5A of the rotary tillage device 5 to measure the tillage depth of the rotary tillage device 5 is A / A.
A system for inputting through the D converter 19 is formed, and a system for outputting a drive signal from the control device 16 to the transistors 20 and 20 as power supply means is formed. A power system for supplying a current to the electromagnetic solenoids 12S and 13S of the pilot valve 12P and the descending pilot valve 13P, respectively, is formed.

In this control system, the control device 16 and the A / D
A switch 2 for supplying power from the battery 21 as a power source to the converter 19, the respective transistors 20 and the like, and supplying power to the ignition plug of the engine E
2 (a system for starting the starter motor is not shown), and a resistor R for converting a current actually flowing to the electromagnetic solenoids 12S and 13S into a voltage value. The resistor R converts the current into a voltage. A signal system for sending a voltage signal to the A / D converter 19 and feeding back the voltage signal to the control device 16 via the A / D converter 19 is formed. The measuring means is constituted by a system that feeds back the voltage signal from the resistor R via the A / D converter 19 to the control device 16.

In this agricultural tractor, the lever sensor 17S
Position control for raising and lowering the rotary tilling device 5 until the height of the rotary tilling device 5 with respect to the vehicle body set by the above is substantially equal to the height of the rotary tilling device 5 with respect to the vehicle body measured by the lift arm sensor 2S; Two types of feedback control: automatic plowing control for raising and lowering the rotary tillage device 5 so that the tillage depth set by the setting device 18S substantially matches the tillage depth of the rotary tillage device 5 measured by the cover sensor 5S. During this control, a setting system consisting of a lever sensor 17S and a tillage depth setting device 18S, and a lift arm sensor 2
S, the larger the deviation from the feedback system composed of the cover sensor 5S, the greater the deviation from the feedback system.
(For example, proportional control or proportional integral control), and when the measured value of the feedback system reaches a dead zone formed based on the set value of the setting system, the control device stops the elevation of the rotary tillage device 5. Sixteen basic control operations are set.

As described above, when setting the elevating speed of the rotary tilling apparatus 5 based on the deviation, a target current value supplied to the electromagnetic solenoids 12S and 13S is set in accordance with the deviation. The intermittent signal (drive signal) of the duty ratio corresponding to the value is controlled to be transmitted to the base terminal of the transistor 20.
1 is low, or a current corresponding to the drive signal is a current corresponding to the drive signal, such as when the electric resistance of the electromagnetic solenoids 12S and 13S changes due to the effect of temperature.
13S, the duty ratio of the drive current is corrected, and the current that becomes the target current value is supplied to the electromagnetic solenoid 12S.
Control to flow to S and 13S is performed, and the details of the control will be described below by taking position control as an example.

That is, as shown in the flowchart of FIG. 5, the signal value (Lo) of the lever sensor 17S and the signal value (Ls) of the lift arm sensor 2S are input,
If the absolute value (| Lo−Ls |) of the deviation of each signal value is larger than the preset dead zone (E), (L
o, Ls), a target current value (Io) to be supplied to one of the electromagnetic solenoids 12S, 13S based on preset table data or a predetermined calculation formula. The duty ratio (D) of the drive signal for driving the transistor 20 is determined and set based on preset table data or a predetermined formula based on the duty ratio. Like a DRAM type memory, the correction is performed by multiplying by a correction value (C) held in a storage unit in which data disappears when the supply of current is stopped, and a drive signal having a duty ratio corrected in this way is required. Output to the transistor 20 on the solenoid side (# 101 to # 106)
Steps).

The driving signal has a period T as shown in FIG.
Is output as an intermittent signal that switches between the ON state and the OFF state, and the ratio of the ON state time to the period T is called a duty ratio (usually expressed as a percentage), and the ON time ratio is increased. When this is done, the current value supplied from the battery 21 to the electromagnetic solenoid via the transistor 20 increases, and when the ON time is reduced, the current value supplied from the battery 21 via the transistor 20 to the electromagnetic solenoid 12
The current value supplied to S and 13S decreases.

Next, the control current value (Ir) actually flowing to the electromagnetic solenoid is input to the control device 16 based on the signal converted into the voltage signal by the resistor R, and the control current value (Ir) and And (Io / Ir) only when the absolute value (| Io-Ir |) of the deviation of each signal value from the target current value (Io) is larger than a preset dead zone (E).
r), the result of the calculation is set as an adjustment coefficient (K), the adjustment coefficient (K) and the correction value (C) are multiplied by a duty ratio (D) of the drive signal, and the multiplied value is obtained. Is output to the transistor 20 (steps # 107 to # 110).

Further, when the interval timer has reached the ON state, the adjustment coefficient (K) is updated to the correction value (C), and this correction value (C) is used in the subsequent control.
Is used to determine the value of the duty ratio (D). Then, the signal value (Lo) of the lever sensor 17S and the signal value (L) of the lift arm sensor 2S are controlled by this control.
When the absolute value (| Lo-Ls |) of the deviation from (s) becomes smaller than a preset dead zone (E), the supply of current to the electromagnetic solenoid is cut off (# 1).
11 to # 113 steps). The interval timer is configured by software and is in the ON state at the start of the control. After the correction value is set in the ON state, the interval timer is set to the ON state again after a set time of about several minutes elapses. Although not described in detail, when the correction value (C) is not set after reaching the ON state, the ON state is maintained.

Since the rotary tilling apparatus 5 is moved up and down by operating the position lever 17 as described above, the processing using the correction value (C) and the adjustment coefficient (K) are used as described above. Lever sensor 17S
Is supplied to the electromagnetic solenoid corresponding to the difference between the signal value of the lift arm sensor 2S and the signal value of the lift arm sensor 2S, and ascends and descends at a speed corresponding to the difference. Lifting is stopped. In particular,
Since the correction value (C) is updated at predetermined intervals by comparing the current value actually flowing to the electromagnetic solenoid with the target current value, the correction value is always updated based on the current value flowing to the electromagnetic solenoid. The processing time can be reduced as compared with the setting, and the drive signal having the duty ratio corrected by the correction value (C) is set from the start of the output of the drive signal. There is almost no change in the amount of hydraulic oil as compared with the case where the correction process is performed after this, and thus, there is no occurrence of a control delay or a disadvantage that the operating speed of the lift cylinder 1 changes.
The operation can be performed quickly and smoothly. And
Since the correction value (C) disappears due to the interruption of the power to the control device 16, even when the same control is performed again after the engine E is stopped, the correction value (C) is always set to the initial value "1". Since the correction process is performed using this value, the output of the drive signal whose duty ratio is set by the incorrect correction value (C) is avoided.

[Another Embodiment] The present invention can be applied to, for example, the automatic plowing depth control and the rolling control in addition to the above-described embodiment. It is also possible to apply the present invention to load control for raising and lowering.

[Brief description of the drawings]

FIG. 1 is a perspective view of the rear part of an agricultural tractor.

FIG. 2 is a hydraulic circuit diagram

FIG. 3 is a block circuit diagram of a control system.

FIG. 4 is a diagram showing a duty ratio of an intermittent signal.

FIG. 5 is a flowchart of position control.

[Explanation of symbols]

 Reference Signs List 1 hydraulic actuator 2S, 5S sensor 12S, 13S electromagnetic solenoid 17S, 18S setting device 16 control device 20 power control means 21 power supply 22 switch E engine P hydraulic pump V control valve C correction value Io target current value Ir current value

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2B304 KA12 LA02 LA06 LB05 LB15 MA03 MA04 MA08 MB02 MC08 MC11 MD02 MD04 PB06 PC15 PD06 PD18 PD28 PD33 QA14 QA16 QB06 QB27 3H002 BA01 BB01 BC05 BD04 BE05 5H004 GA13 GA15 GB12 HA14 JB14 MA02 MA06 MA42

Claims (4)

[Claims] 1. A hydraulic drive system for supplying hydraulic oil from a hydraulic pump driven by an engine to a hydraulic actuator via an electromagnetic proportional control valve, and a setting device for setting an operation target of the hydraulic actuator. Setting signal,
A control device to which a detection signal from a sensor for detecting an operation position of the hydraulic actuator is input, and power control means for supplying a current from a power supply to an electromagnetic solenoid of the control valve based on a drive signal from the control device. A target current value is set based on a deviation between a setting signal from the setting device and a detection signal from the sensor, and a drive signal set in accordance with the target current value is sent to the power control means. A work vehicle in which the control mode of the control device is set, comprising a measuring unit that measures a current value flowing to an electromagnetic solenoid of the control valve, and a current value measured by the measuring unit.
If there is a difference from the target current value, a correction value capable of compensating for the difference is set, and after setting the correction value, the control mode of the control device is configured to correct the drive signal with the correction value. Work vehicle set. 2. A coefficient obtained by dividing the target current value by a current value measured by the measuring means is set to the correction value, and the coefficient corresponding to the target current value is controlled when the hydraulic actuator is controlled. The work vehicle according to claim 1, wherein the control mode of the control device is set to correct the drive signal by multiplying the set drive signal by a correction value. 3. The work vehicle according to claim 1, wherein a control mode of the control device is set such that the correction value is updated every set time. 4. A switch for operating the engine by an on operation, supplying electric power to electric equipment of a vehicle body, stopping the engine by an off operation, and stopping power supply to electric equipment of the vehicle body, wherein the switch is provided. 2. The work vehicle according to claim 1, wherein the correction value is set only when the vehicle is in an on state, and the correction value set by a switch-off operation is deleted.