JP2578685Y2 - Control device for electromagnetic proportional control valve in work vehicle - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electromagnetic proportional control valve in a working vehicle such as a tractor, a rice transplanter, a combine, or the like.

[0002]

2. Description of the Related Art
Some of these types of working vehicles include a descent of a working unit that descends from a non-working position in order to prevent a so-called dusting phenomenon in which the traveling body suddenly starts due to a reaction force (tiling reaction force or the like) that the working unit receives when touching down. Some include anti-dusting control means for reducing the speed near the ground contact position. However, in a hydraulic cylinder that raises and lowers the working unit, the operating speed is controlled using an electromagnetic proportional control valve that proportionally controls a flow rate based on a current value input to a solenoid unit.
Since the control flow rate of the electromagnetic proportional control valve fluctuates due to a change in coil resistance value due to a temperature change, a change in viscosity of hydraulic oil, and a change in engine speed , the hydraulic pressure is controlled based on anti-dusting control. When the operating speed of the cylinder is reduced, the operation may be too slow depending on the temperature at that time, or the speed may not be sufficiently reduced, which may cause inconveniences such as a decrease in accuracy and stability in the anti-dusting control. Was.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has been made to provide a control device for an electromagnetic proportional control valve in a working vehicle that can eliminate these disadvantages. The control of the operating speed of a hydraulic cylinder that raises and lowers the ground working unit is performed by an electromagnetic proportional control valve that proportionally controls a flow rate based on a current value input to a solenoid unit. Input current value control means for controlling the input current value based on pulse width modulation, and a control unit for controlling the input current value of the working unit to decrease the descending speed of the working unit descending from the non-working position near the ground position. In a working vehicle provided with anti-dusting control means for controlling a current value, the control unit determines whether or not the ground working unit has been raised to a non-working position. If it is determined to have been created, et
Measures the voltage fluctuation due to the change in the engine speed and the coil resistance of the solenoid that fluctuates according to the oil temperature change, and corrects the minimum ON time during anti-dusting control based on the measured coil resistance fluctuation. A minimum ON time correction means for performing the operation. And the present invention is
With this configuration, highly accurate and stable anti-dusting control can be performed regardless of a temperature change.

[0004]

Next, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling body of a tractor, and a rotary tilling type working unit 3 is connected to a rear portion of the traveling body 1 via a lifting link mechanism 2 so as to be able to move up and down. The lifting and lowering is performed based on the vertical swing of the lift arm 5 associated with the hydraulic operation of the single-acting lift cylinder 4, and all of these basic configurations are the same as in the related art.

Numeral 6 denotes an electromagnetic proportional control valve for controlling the extension operation (upward movement of the working unit) and the reduction operation (downward operation of the working unit) of the lift cylinder 4. The electromagnetic proportional control valve 6 is a solenoid for raising and lowering the solenoid. The expansion and contraction operation of the lift cylinder 4 is switched by piloting the ascending and descending main valves V ₁ and V ₂ based on the excitation operation of the ascending and descending solenoids 6 a and 6 b.
The operation speed of the lift cylinder 4 is controlled by proportionally controlling the flow rate on the basis of the current value input to the b. The input current value is adjusted based on the pulse width modulation control. The operating speed of the lift cylinder 4 is determined by the ratio (ON time ratio). Further, in the hydraulic circuit of the present embodiment, when a temperature change such as an oil temperature occurs, the hydraulic circuit shows a temperature characteristic as shown in FIG.
That is, in the ascending operation, the coil resistance of the ascending solenoid 6a increases as the temperature rises, and the flow rate decreases based on the decrease in the coil current value as the coil resistance increases. , increases the temperature rise coil resistance accompaniment with the lowering solenoid 6b is, although the flow rate is reduced based on the reduction of the coil current value with the increase of the coil resistance value, the throttle resistance of the descending speed control valve V ₃ Because of the decrease, the flow rate will increase.

On the other hand, an operation panel 8 is provided near the driver's seat 9 and has a position lever 10 (an operation signal is a lever angle sensor) for raising and lowering the working unit 3. 10a), an automatic control switching switch 11 for switching the automatic control, a tillage depth setting volume 12 for setting a target tillage depth of a tillage depth automatic control described later, and a starting position for the anti-dusting control described later. There are provided operation tools such as a position setting volume 13 for setting the operation mode and a mode switching switch 14 for switching the control mode. Operation signals of the operation tools are input to the control unit 15. ing.

The control section 15 is constructed using a so-called microcomputer (including a CPU, ROM, RAM, etc.). Signals are input from an arm angle sensor 16 for detecting a swing angle, a tillage depth detection sensor 18 for detecting a tillage depth based on a vertical swing angle of a rear cover 17, an engine rotation sensor 19 for detecting an engine speed, and the like. According to the determination based on these input signals, an operation pulse signal is output to the ascending solenoid 6a and the descending solenoid 6b of the electromagnetic proportional control valve 6 via the driving transistors Tr1 and Tr2.
Inputs the ground current value of the ascending solenoid 6a via the amplifier circuit 20. That is, the ground current of the ascending solenoid 6a is divided by the resistor R, and the divided current is amplified by the amplifier circuit 20, and then the A / D converter (analog-digital conversion circuit)
22 to be input to the control unit 15 via
For this reason, the control unit 15 can measure the temperature of the electromagnetic proportional control valve 6 based on the coil resistance value of the ascending solenoid 6a that fluctuates with a change in temperature.

Next, control in which a control procedure is stored in the control unit 15 in advance, that is, measurement reference data correction control executed in a factory inspection line, an operation position of the position lever 10 and a detection position of the lift arm 5 are determined. Position control for raising and lowering the working unit 3 so as to match them, and automatic tillage depth control for raising and lowering the working unit 3 so as to match the set tillage depth of the tillage depth setting volume 12 and the tillage depth detected by the tillage depth sensor 18; Dusting prevention control for gradually lowering the descending speed of the working unit 3 descending from the non-working position from the set position of the position setting volume 13 will be described.

The measurement reference data correction control is executed when the mode switching switch 14 is set to the check mode position and a predetermined operation is performed. When the control is executed, the control is kept constant. The temperature of the hydraulic oil is measured in advance using a measuring device, and the temperature range to which the measured temperature belongs is input to the control unit 15 based on the switching operation of the automatic control switching switch 11. Shall be kept. When the measurement reference data correction control is executed after the completion of these preparations, the control
Ascending solenoid 6 for repeatedly raising and lowering working unit 3
a, and outputs an operation pulse to the descending solenoid 6b, samples a plurality of temperature measured values based on the coil resistance value during the ascending operation, averages the sampled temperature measured values, and then based on the average value. Thus, the measurement reference data stored in the memory (with a backup) is corrected. That is, the inconvenience of causing a measurement error due to the quality variation in the amplifier circuit 20 and the electromagnetic proportional control valve 6 is prevented.

On the other hand, in the position control, the operation position of the position lever 10 is compared with the detection position of the lift arm 5, and when the operation position of the position lever 10 is higher than the detection position of the lift arm 5, When the operation position of the position lever 10 is lower than the detection position of the lift arm 5, a decrease operation pulse of the duty ratio corresponding to the difference is output. When the operation position of the position lever 10 coincides with the detection position of the lift arm 5, the output of the operation pulse is stopped, but the operation position of the position lever 10 is changed to the detection position of the lift arm 5. If it is higher than the threshold value and the difference is large, the ascending operation pulse having the maximum duty ratio within the set range is output. In this state, a plurality of temperature measurement values are sampled based on the coil resistance value, the sampled temperature measurement values are averaged, and then the duty ratio of the operation pulse is corrected based on the average value. . That is, the duty ratio is corrected every time when the working unit 3 is lifted to the non-working position, and the ON time of the operation pulse, that is, the temperature measurement time is secured as long as possible. In this embodiment, the measurement value is corrected based on the engine speed, so that the inconvenience that a measurement error occurs due to the voltage fluctuation due to the change in the engine speed is eliminated. You can do it.

In the above-described automatic plowing depth control, it is first determined whether or not the automatic plowing depth control is ON based on the operating states of the automatic control switching switch 11 and the position lever 10. That is, while the automatic control switching switch 11 is set to the automatic cultivation depth position and the position lever 10 is operated to the lower limit position, the automatic cultivation depth control is executed. The setting state of the work start flag which is set when the lever 10 is raised to the non-work position is determined. When the work start flag is in the reset state, the working unit 3 is controlled to move up and down at a normal speed so that the set plowing depth of the plowing depth setting volume 12 and the plowing depth detected by the plowing depth detection sensor 18 are made to match. When the work start flag is in the set state, the work start flag is reset when the work unit 3 reaches the vicinity of the set plowing depth after executing the above-described anti-dusting control. In the plowing depth automatic control, an operation pulse whose duty ratio is corrected based on the temperature measurement is used. In the anti-dusting control, more precise pulse correction is performed. That is, in the deceleration range of the anti-dusting control,
The ON time of the operation pulse is sequentially reduced (decrease width = Δt) until a preset minimum ON time t ₀ is reached.
The minimum ON time is corrected on the basis of the above-mentioned temperature measurement value. Therefore, it is possible to eliminate inconveniences such as a descent speed during the anti-dusting control becoming too slow or not being sufficiently decelerated due to a temperature change. You can do it.

In the embodiment of the present invention configured as described above, in the deceleration range of the anti-dashing control, the ON time of the operation pulse input to the electromagnetic proportional control valve 6 is set to a predetermined minimum ON time t0. The control unit 15 that outputs the operation pulse sequentially measures the temperature of the electromagnetic proportional control valve 6 based on the coil resistance value of the ascending solenoid 6a, and determines the minimum value of the operation pulse based on the measured temperature value. The ON time t0 is corrected, and therefore, the inconvenience such as the descent prevention speed becoming too slow or not being sufficiently decelerated during the anti-dusting control due to the temperature change is eliminated, thereby improving the accuracy and stability of the anti-dusting control. Can be improved .

The present invention is, of course, not limited to the above-described embodiment. For example, correction of measurement reference data in a factory inspection line is performed as in the second embodiment shown in FIG. Can also. That is, in the second embodiment,
When inputting the operating oil temperature measured using the measuring device to the control unit 15, the input temperature is set and input in a stepless manner based on the operation of the tillage depth setting volume 12, so that the temperature range is set. than that of the first embodiment to input a correction metric data can be performed with high accuracy.

[0014]

[Effects] In summary, the present invention is constructed as described above, so that the hydraulic cylinder for raising and lowering the working unit is controlled to prevent dusting based on the flow rate control of the electromagnetic proportional control valve, and the temperature is controlled. The coil resistance value of the solenoid portion which fluctuates according to the change is measured, and the correction of the minimum ON time at the time of the anti-dusting control, which is performed based on the measured coil resistance value, is accompanied by a change in the engine speed.
Automatically taking into account voltage fluctuations, the oil
Inconvenience that the minimum ON time fluctuates due to the temperature change and the current change can be prevented. Accordance connexion, or too slow lowering speed of the working unit in Datsushingu prevention control time based on the temperature change and the like of the hydraulic oil, the accuracy and stability of reliably eliminated to Datsushingu prevention control problems such that not sufficiently decelerated kill at improvement.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a plan view of an operation panel.

FIG. 3 is a block circuit diagram showing a schematic configuration of a control mechanism.

FIG. 4 is a flowchart of measurement reference value setting control.

FIG. 5 is a flowchart of position control.

FIG. 6 is a timing chart showing the operation of the position control.

FIG. 7 is a graph showing a correction range.

FIG. 8 is a flow chart of automatic plowing control.

FIG. 9 is a flow chart of anti-dusting control.

FIG. 10 is a timing chart showing the operation of anti-dusting control.

FIG. 11 is a flowchart of measurement reference value setting control according to the second embodiment.

FIG. 12 is a hydraulic circuit diagram including an electromagnetic proportional control valve.

FIG. 13 is a graph showing temperature characteristics of the electromagnetic proportional control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Traveling body 3 Working part 4 Lift cylinder 6 Electromagnetic proportional control valve 6a Elevating solenoid 6b Descent solenoid 10 Positioning lever 15 Control part 20 Amplifier circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. An electromagnetic proportional control valve for controlling an operating speed of a hydraulic cylinder for raising and lowering a ground working unit by proportionally controlling a flow rate based on a current value input to a solenoid unit. Input current value control means for controlling the input current value based on pulse width modulation, and a control unit for controlling the input current value of the working unit to decrease the descending speed of the working unit descending from the non-working position near the ground position. In a working vehicle provided with anti-dusting control means for controlling a current value, the control unit determines whether or not the ground working unit has been raised to a non-working position, and determines that the lifting operation has been performed. When the engine speed changes
The minimum ON which measures the coil resistance of the solenoid portion which fluctuates according to the voltage fluctuation and the oil temperature change, and corrects the minimum ON time at the time of the anti-dusting control based on the measured coil resistance fluctuation. A control device for an electromagnetic proportional control valve in a working vehicle, comprising a time correcting means.