JP2002223605A - Working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly actuate a hydraulic cylinder by supplying an electromagnetic solenoid of an electromagnetically proportional type control valve with an appropriate electric current to avoid a shock accompanied with individual differences of the control valves, etc. SOLUTION: This working vehicle has a mechanism comprising setting an amount of a hydraulic fluid charged into a soft cylinder to a rather smaller value to avoid the shock, etc., when controlling lifting and lowering of a rotary tiller apparatus, assuming a working distance of the soft cylinder based on the amount of the hydraulic fluid set to the rather small value, detecting the assumed working distance and the actually moved distance of the soft cylinder at the set amount of the hydraulic fluid each as detected values LS' and LS" by a soft arm sensor, comparing the detected values LS' and LS" and applying a corrected current value IO to the target current IO of the electromagnetically proportional control valve for correcting the initially set amount of the hydraulic fluid to redrive the soft cylinder when the actual working distance doesn't reach the assumed working distance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an oil amount-current characteristic in which the amount of hydraulic oil supplied to a hydraulic actuator for driving a working device is determined by a predetermined operating current. A control device which is adjusted by an electromagnetic proportional control valve and receives a setting signal from a setting device for setting a target operation amount for the hydraulic actuator and a detection signal from an operation position detection sensor for detecting an operation position of the hydraulic actuator. The operating oil value is set based on a target operating amount from the setter, and the operating current value of the electromagnetic proportional control valve is controlled by the control device based on the oil amount-current characteristic from the operating oil amount. A work vehicle configured to calculate.

[0002]

2. Description of the Related Art In an electromagnetic proportional control valve, the operating current value and the amount of hydraulic oil supplied through the electromagnetic proportional control valve are determined by individual differences in control valve, oil temperature, weight of working equipment, control current error of control unit, and the like. Thus, the electromagnetic proportional control valve has different characteristics. Therefore, as shown in FIG. 3, the oil amount-current characteristic has a hysteresis indicated by a characteristic line d forming a certain width with respect to a reference characteristic line c.

[0003]

Therefore, the operation oil amount is set based on the target operation amount from the setter, and the control device operates the electromagnetic proportional control valve based on the oil amount-current characteristic from the operation oil amount. When the current value is calculated, since the operating current value does not become a current value in consideration of the individual difference of the valve and the like, a difference occurs between the target flow rate and the actually flowing flow rate, and the actual flow rate is large. In such a case, a large shock occurs at the time of stoppage, and when the actual flow rate is small, the movement is slow and sometimes does not move. In particular, when the flow rate is a low flow rate of 5 liters or less, since the absolute amount of the required flow rate is small, the influence of hysteresis is likely to occur, and it has been difficult to set an appropriate flow rate. An object of the present invention is to provide a control structure capable of absorbing an individual difference or the like of a control valve, suppressing a stop shock, and supplying a flow rate capable of moving at an appropriate speed.

[0004]

[Means for Solving the Problems] [Configuration] A first feature (claim 1) of the present invention is that the operating speed of the hydraulic actuator is lower than the operating current value calculated based on the oil amount-current characteristic. Is selected as a target current value, an operation amount of the hydraulic actuator is assumed based on the target current value, and an operation amount of the hydraulic actuator driven by the target current value is actually operated. Detected by a sensor, comparing the assumed operation amount with the detected operation amount, and if the detected operation amount is smaller than the assumed operation amount, increases or decreases a correction current value with respect to the target current value. A correction means is provided for controlling the electromagnetic proportional control valve according to the corrected target current value. The operation and effect of the correction means are as follows.

[Operation] First, a target current value to be supplied to the electromagnetic proportional control valve when starting the control is set. This target current value is an operation in which the operating speed of the hydraulic actuator is slower within the hysteresis than the operating current value indicated by the solid line c in FIG. 3 indicating the oil amount-current characteristic of the electromagnetic proportional control valve. Refers to the current value. When the target current value is supplied, the electromagnetic proportional control valve causes the hydraulic actuator to flow the hydraulic oil amount based on the oil amount-current characteristic into the hydraulic actuator, and receives the flow of the hydraulic oil to estimate the operation amount of the hydraulic actuator. . On the other hand, the hydraulic actuator is actually driven based on the target current value, and the actual operation amount of the hydraulic actuator is detected by the operation position detection sensor. The actual operation amount is compared with the assumed operation amount, and if the actual operation amount does not reach the assumed operation amount, the corrected current value is added to the target current value, and then the corrected target current value is used. Perform control.
Next, based on the corrected target current value, the operation amount of the hydraulic actuator is again assumed and the actual operation amount is detected, the two are compared, and if necessary, the corrected current value is corrected by the corrected current value. The target current value is further corrected. By sequentially repeating the above procedure, the target current value is corrected.

[Effect] Therefore, as a target current value before correction, a sufficiently small current value considering an individual difference is adopted as an operating current value, so that a shock at the time of stop can be reduced and the actual value of the hydraulic actuator can be reduced. Since the correction is performed while detecting the operation amount of the hydraulic actuator, it is possible to avoid that the operation speed is slow or the operation is not performed at all, and it is possible to expect a smooth operation of the hydraulic actuator. By adopting such a control form, the influence of the individual difference of the electromagnetic proportional control valve can be suppressed, which is effective for control in a low flow rate range.

[Structure] Second feature of the present invention (Claim 2)
In claim 1, the correction current value is obtained by multiplying the target current value selected from the oil amount-current characteristic by a proportionality constant, integrating a value obtained by the multiplication, and further proportional to the integrated value. It is a numerical value, and its operation and effect are as follows.

[Effect] Since the correction current value is calculated based on the target current value selected from the oil amount-current characteristics, the correction current value is an absolute value of the target current value, that is, the target current value. The correction current value can also be set to be large or small in accordance with the magnitude of the current value, and is maintained at a value appropriate for correcting the target current value. Therefore, by performing the correction, it is possible to suppress the occurrence of control hunting.

[Structure] Third feature of the present invention (claim 3)
In claim 1, the correction current value is selected such that the correction current value does not exceed a preset correction limit current such that as the target oil supply amount corresponding to the target current value increases, the correction current value conversely decreases. The operation and effect are as follows.

[Effects] The target current value used for correcting the target current value is calculated based on the oil amount-current characteristics. However, it is possible due to some inconvenience of the control system. Assuming that no correction current value may be calculated, the correction current value can be set within a range not exceeding the correction limit current. In addition, the correction limit current is set so that the correction current value decreases as the target supply oil amount corresponding to the target current value increases, so that the effect of the correction in the low flow rate region is remarkable. The operating characteristics of the hydraulic actuator in the low flow rate range are made smooth.

[0011]

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 (an example of a working device) 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. By suspending and supporting the lower link 4 and the lift arm 2 via the lift rod 6, the rotary tilling apparatus 5 can be moved up and down by the driving force of the lift cylinder 1.
The rolling operation of the rotary tilling apparatus 5 can be performed by the expansion and contraction operation of a double-acting rolling cylinder 7 interposed in the right lift rod 6.

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 1.
1 and an oil passage system for supplying the excess flow from the flow priority valve 10 to an electromagnetic proportional lift control valve V. 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 is
An ascending control valve 12 for supplying hydraulic oil to the lift cylinder 1, an ascending pilot valve 12P for opening and closing the ascending control valve 12 with pilot pressure, and a descending control valve 13 for discharging hydraulic oil from the lift cylinder 1. And a lowering pilot valve 13P for opening and closing the lowering control valve 13 with pilot pressure. The ascending pilot valve 12P and the descending pilot valve 13P change their opening in direct proportion to the current value supplied to the respective electromagnetic solenoids 12S, 13S to change the pilot pressure.
2. The opening of each of the descending control valves 13 is adjustable. That is, the elevation control valve V is configured as an electromagnetic proportional control valve.

Since the rotary tilling apparatus 5 is lifted, the pilot valve 1 for lifting 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 device 5 is lowered, a current is supplied to the electromagnetic solenoid 13S of the descending pilot valve 13P, and by adjusting the current value of this current, the opening of the descending pilot valve 13P is increased. 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 is discharged from the lift cylinder 1 in an amount proportional to the opening, and the lowering speed of the rotary tilling device 5 is determined. The characteristics of the elevating flow required for the elevating operation of the elevating control valve V related to the elevating operation of the rotary tillage device 5 and the operating current for setting the opening degree of the elevating control valve V required for flowing the elevating flow are described below. The diagram shown is listed as FIG.

As shown in FIGS. 1 and 13, a potentiometer for measuring an operation position of a position lever 17 (an example of a setting device for setting a target operation amount) provided on a vehicle body with respect to a control device 16 having a microprocessor. Type lever sensor 17S, a potentiometer type lift arm sensor 2S (an example of an operation position detection sensor for detecting the operation position of the hydraulic actuator) for measuring the swing amount of the lift arm 2, and the tillage depth of the rotary tillage device 5. Potentiometer type tillage depth setting device 18S operated by dial 18 to set (an example of a setting device for setting a target operation amount)
And a potentiometer type cover sensor 5S (an example of an operation position detection sensor that detects an operation position of a hydraulic actuator) that measures a swinging amount of a rear cover 5A of the rotary tillage device 5 to measure a tillage depth of the rotary tillage device 5. ) Is input through the A / D converter 19, and a current is supplied from the control device 16 to the electromagnetic solenoids 12S, 13S of the ascending pilot valve 12P and the descending pilot valve 13P, respectively. The power system for the operation is formed.

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. I do.

[0016] During these controls, as shown in FIGS. 5 and 6, first, so as not to cause actuation shock starts the control at the start flow rate Q _S characteristics sequential flow than zero state is increased, a constant flow rate until the supply is carried out the control at the start flow rate Q _S. From the middle of the control, when the deviation rate Q _H is decreased and the deviation rate Q _H to be described later and start flow rate Q _S is reversed, and controls at the deviation flow Q _H.
That is, a setting system including the lever sensor 17S and the tillage depth setting device 18S, the lift arm sensor 2S, and the cover sensor 5S
The larger the deviation from the feedback system, the higher or lower the rotary tilling device 5 (or plow working machine) at a speed (or a preset speed) proportional to the deviation (for example, proportional control or proportional integral control), and the setting system The basic control operation of the control device 16 is set so that the elevation of the rotary tilling device 5 is stopped when the measured value of the feedback system reaches the dead zone formed based on the set value of.

Next, a control mode for the elevation control valve V will be described. It has been stated that the relationship between the operating current supplied to the lift control valve V and the flow rate of the lift cylinder 1 is proportional. However, in the actual test results, as shown in FIG. Shows the oil amount-current characteristics of As shown in FIG. 3, the oil amount-current characteristic depends on the individual difference of the lift control valve V, the oil temperature, the difference in the internal pressure of the lift cylinder 1 due to the weight of the working device such as the rotary tilling device, etc. Has a hysteresis that fluctuates within a certain width surrounded by two rows of dotted lines d and d. Then, in the lift control valve V, the oil amount-current characteristic at the time of the raising operation for supplying the hydraulic oil to the lift cylinder 1 and the oil amount-current characteristic at the time of the lowering operation slightly shift as shown in FIG. I have. Oil amount as described above - the lift control valve V having a current characteristic, compares the start flow rate Q _S which is set in advance with the deviation rate Q _H based on the deviation as described above, lift cylinder the flow rate of the smaller 1 is supplied.

[0018] start the flow rate Q _S, as shown in FIG. 9,
It is selected along the characteristic line where the flow rate increases with time,
The deviation flow rate Q _H is, as shown in FIG.
Based on the setting signal in the setting system such as 8S and the detection signal of the feedback system including the lift arm sensor 2S and the like, the larger the deviation is, the larger the capacity is selected along the characteristic line. To perform a basic control these two flow rates, as shown in FIG. 6 an enlarged portion for the elevation control in FIG. 5, at the time of control start, the start flow rate Q _S at a slightly larger flow rate from zero value There, the deviation between the detected value of the set values, such as position lever 17 and the lift arm sensor 2S is because a large, will begin to control the start flow rate Q _S. Referring to FIG. 5, the operation time is plotted on the horizontal axis, and a deviation appears between the set value of the position lever sensor and the detection value of the lift arm sensor at 25 seconds and 50 seconds after the start of operation. FIG. 6 shows that the position control has been performed, and the control state at 25 seconds after the start of operation is enlarged.

[0019] That is, as shown in the flowchart of FIG. 5 and FIG. 7, position lever sensor 17S settings (signal value) detected value of L _o and the lift arm sensor 2S (signal value) difference between the L _S If produced, first, it starts the control at the start flow rate _{Q S (# 1~ # 4)} . And the start flow rate Q start flow rate starts controlling in the course of one second little over _S Q _S and deviation flow Q _H becomes the same flow rate, and thereafter would control Deviation flow Q _H is performed. When the set value of the position lever sensor 17S matches the detection value of the lift arm sensor 2S, the elevation control valve V stops supplying. Q _e in FIG. 5 and FIG. 6, the start flow rate Q _S
And indicating the last lift flow to be introduced either the smaller flow rate actually lift cylinder 1 and selected in the error to flow Q _H (# 5). As described above, although the above-described control is performed when the discrepancy comes into the detection value L _S of the set value L _o and the lift arm sensor 2S position lever sensor 17S, a phenomenon in which the discrepancy is out, the lift cylinder It is caused by oil spilling from inside 1 or by operating the position lever 17.

Next, a portion corresponding to the present invention will be described. As described above, since the elevation control valve V has a hysteresis of a certain width in the elevation flow supplied by the individual difference or the like even when the same operating current is applied, it is possible to avoid the occurrence of a shock due to the excessive elevation flow. From a viewpoint, when supplying hydraulic oil to the lift cylinder 1, control is started by inputting an oil amount (a vertical flow rate) that does not easily cause a shock. In this case, the amount of operating current that indicates the ascending / descending flow rate is indicated by a solid line c 'in FIG. Next, the lift arm 2 assumes a lift amount of lifting by the lifting flow hardly out shock clogging start flow Q _S. That is,
The target current value I _o is selected from FIG. 3 based on the starting flow rate Q _S, determines the duty ratio D for driving the lift control valve V (# 6).

Start flow rate Q_SElevation control valve V required for
As the drive current value I, the target current value I_ogive,
The target current value I_oOf the lift arm 2 corresponding to the
Is assumed. The estimated amount of expansion and contraction is calculated using the lift arm sensor 2S.
Detection value (signal value) L_SPredicted value L of the amount of change in_S'
(# 7), and the predicted value L_S'And lifters
Value detected by the load sensor 2S, that is, the lift arm
Signal value L of sensor 2s _SActual change L_S''
The amount of movement of the lift arm 2 (actual change amount L_S'') Is assumed
Quantity (predicted value L_S') If the value is less than
(# 9).

[0022] subjected to correction, multiplied by a proportional constant k to lift flow value initially charged, further, by integrating the lift flow kQ _S multiplied by the proportional constant k, further integrated over the integration value ∫KQ _S The value α∫kQ _S multiplied by the constant α is corrected current value I
_o '. When the correction current value I _o ′ is determined, the correction drive current I is calculated by adding the target current value I _o to the current value. Driving is performed with the corrected driving current I (# 10). The correction current value I _o 'is as shown in FIG. 8, an elevation rate Q has a correlation, elevating flow 5 l and the maximum correction current I _o' '
It is set to a value that does not exceed the value shown on the flow rate-maximum correction current characteristic line connecting 150 mA. The maximum correction current I _o ″ is one of the correction limit currents that limit the correction current value I _o ′. Further, the correction current value I _o ′ is always added to the target current value I _o , and is not subtracted. This eliminates an increase or decrease in the amount of oil supply due to an increase or decrease in the current value,
The shock of the working device can be reduced.

If the movement amount (actual change amount L _S ″) of the lift arm 2 is the same as the assumed amount (predicted value L _S ′), the drive current I is set to the target current value I _o (# 14 to # 14). # 1
5). When the error to flow Q _H is large relative to the start flow rate Q _S, the flow chart # 6, as described in # 7, and sets the target current value I _o and the drive duty ratio D on the basis of a deviation rate Q _H (# 11 ), The predicted movement value L _S ′ of the lift arm 2 is calculated (# 12), and the process shifts to comparison with the detected value L _S ″ of the actual movement amount of the lift arm 2 (# 8).

[0024] As described above, shows the state of operation by adding a correction to the target current value I _o is 11 and 12, the correction current value I _o relative to the target current value I _o ', the correction current An example of a possible value I _o ″ of the maximum correction current with respect to the value I _o ′ is shown, and the elevation control valve V is driven by the total current value of the target current value I _o and the correction current value I _o ′. You. Referring to FIG. 11, the operation time is indicated on the horizontal axis, which indicates that the control was started when the detection value of the lift arm sensor deviated from the target value at 40 seconds and 85 seconds after the start of operation. FIG. 12 is an enlarged view of a portion at 40 seconds after the start of operation.

[Another Embodiment] a. The present invention can be applied to, for example, automatic tillage depth control and rolling control in addition to the above-described embodiment, and can also be applied to draft control for raising and lowering a working device such as a plow. . When performing this draft control, a draft sensor 9 provided on the lower link 4 is provided in order to detect a setting value of a potentiometer type draft setting device 8 provided in the control section and a working resistance acting on a working device such as a plow. Is controlled to move the plow operating device up and down so that the detected value of the plow working device coincides with the detected value. B. In the above embodiment, the flow rate of the hydraulic oil supplied to the lift cylinder 1, the start flow rate Q _S and deviation flow Q _H
Had to adopt the smaller one flow with, it may be carried out only by controlling the error to flow Q _H. C. When calculating the correction current value I _o ′, the correction current value I _o ′ was calculated based on the target current value I _o calculated from the oil amount-current characteristic line shown in FIG. A target flow rate corresponding to the value _Io may be used. two. As a sensor for detecting the operating position of the hydraulic actuator 1, the movement of the lift arm 2 driven by the actuator 1 is detected, but a stroke sensor or the like for detecting the movement of the hydraulic actuator 1 itself may be used. .

[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 diagram showing a hysteresis state in an oil amount-current characteristic in a current proportional control valve.

FIG. 4 is a diagram showing an oil amount-current characteristic in an electromagnetic proportional control valve.

FIG. 5 is a diagram showing an amount of oil supplied to a lift arm in position control when a deviation occurs between a position lever sensor and a lift arm sensor.

FIG. 6 is an enlarged view of a control part in FIG. 5;

FIG. 7 is a flowchart showing a correction state of an operating current supplied to the electromagnetic proportional control valve in the position control.

FIG. 8 is a diagram showing a relationship between a correction limiting current for limiting a correction current and an ascending and descending flow rate.

FIG. 9 is a diagram showing a temporal change of a start flow rate.

FIG. 10 is a diagram showing a relationship between a deviation flow rate and a deviation.

FIG. 11 is a diagram showing a correction current value for the electromagnetic proportional control valve in the position control when a deviation occurs between the position lever sensor and the lift arm sensor.

FIG. 12 is an enlarged view of a control part in FIG. 11;

FIG. 13 is a control block diagram.

[Explanation of symbols]

Reference Signs List 1 hydraulic actuator 2S, 5S operating position detection sensor 16 controller 17S, 18S setting unit V control valve _Io target current value _Io 'correction current value _Io ''correction limit current

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2B304 KA14 LA02 LA06 LB05 LB15 MA03 MA04 MB02 MC08 MD02 MD03 MD04 PD19 QA03 QA08 QA12 QB02 QB13 QB15 QC03 QC14 QC17 RA28 3H089 AA50 AA50 AA67 BB06 CC01 DA02 DB12 EE31 EE31 EE31 FE31 DA05 EE04 EE07 EE27 EE48 FB07 FB27 FB46 KK03 KK17

Claims (3)

[Claims] 1. An electromagnetic proportional control valve having an oil amount-current characteristic that determines an oil amount that can be supplied by a predetermined operating current to a hydraulic oil supply amount to a hydraulic actuator that drives a working device. A control device to which a setting signal from a setting device for setting a target operation amount for the hydraulic actuator and a detection signal from an operation position detection sensor for detecting an operation position of the hydraulic actuator are provided, A hydraulic oil amount is set based on a target operating amount from the hydraulic oil amount, and the control device calculates an operating current value of the electromagnetic proportional control valve from the hydraulic oil amount based on the oil amount-current characteristic. A working vehicle, wherein the operating speed of the hydraulic actuator is lower than the operating current value calculated based on the oil amount-current characteristic. Is selected as a target current value, an operation amount of the hydraulic actuator is assumed by the target current value, and an operation amount of the hydraulic actuator actually driven by the target current value is detected by the operation position detection sensor. Comparing the assumed amount of operation with the detected amount of operation, if the detected amount of operation is smaller than the assumed amount of operation, increase or decrease a correction current value with respect to the target current value to perform correction. A work vehicle including a correction unit that controls an electromagnetic proportional control valve according to a corrected and corrected target current value. 2. A corrected current value is obtained by multiplying a target current value selected from an oil amount-current characteristic by a proportional constant, integrating a value obtained by the multiplication, and further calculating a numerical value proportional to the integrated value. The work vehicle according to claim 1, wherein 3. The correction current value is selected such that the correction current value does not exceed a preset correction limit current so that the correction current value decreases as the target oil supply amount corresponding to the target current value increases. The work vehicle according to claim 1.