JPH0942213A - Hydraulic control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute control while setting a sensor valve to a neutral reference value at the start of operation by setting a preset standard value to the neutral reference value if a position is determined to be inappropriate. SOLUTION: An operating transformer 51 is used for detecting the spool position of a lift cylinder switching valve 42, and feedback control of the spool position is performed based on the detected value; at the start of operation, the spool position of the lift cylinder switching valve 42 is determined in accordance with a detection signal of the operating transformer 51 and, if the spool position is within the proper range, the current detected value of the current position of the operating transformer 51 is set to a neutral reference value. When the spool position is out of the proper range, a preset standard value is set to the neutral reference value and therefore the detected value other than neutral can be prevented from being set to the neutral reference value by mistake, with the result that the inconvenience of control being executed on the basis of the neutral reference value set by mistake can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of hydraulic control devices provided in agricultural machines, construction machines and the like.

[0002]

2. Description of the Related Art Generally, some hydraulic control devices of this type detect a spool position of a hydraulic valve with a sensor and feedback-control the spool position based on a value detected by the sensor.

[0003]

By the way, in such a system, it is general to compare the detected value of the sensor with the neutral reference value and judge the current spool position based on the deviation. If a deviation occurs between the neutral reference value and the actual neutral detection value, the control accuracy cannot be reduced, and the hydraulic actuator may malfunction. Therefore, it has been proposed to set the sensor value detected at the beginning of operation to the neutral reference value, paying attention to the fact that the spool is positioned at the beginning of the operation. Even if the vehicle is located at a position other than neutral for the reason, there is a possibility that the sensor value at the start of operation will be set to the neutral reference value and control will be executed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made with the object of providing a hydraulic control device capable of solving these problems in view of the above circumstances, and is a spool of a hydraulic valve. A hydraulic control device that detects a position with a sensor and feedback-controls the spool position based on the detection value of the sensor, wherein the hydraulic control device determines the spool position at the start of operation based on the detection value of the sensor. If the determined position is appropriate, the current sensor value is set to the neutral reference value, while if the determined position is incorrect, a preset standard value is set to the neutral reference value. The neutral reference value setting means is provided. In other words, paying attention to the fact that the spool is in the neutral position at the start of operation, and correcting the neutral reference value based on the sensor value detected at the start of operation, but when the spool position at the start of operation is incorrect, , Since the preset standard value is set to the neutral reference value, it is possible to prevent the detection value other than neutral from being erroneously set to the neutral reference value. As a result, based on the erroneously set neutral reference value, It is possible to avoid the disadvantage that the control is executed.

Further, when the hydraulic control device has a proper judgment position, a predetermined notification device is operated in the first pattern, while when the judgment position is not proper,
In the one provided with the spool position notification means for operating the notification device in the second pattern, whether the neutral reference value has been corrected can be recognized based on the notification of the first pattern, or based on the notification of the second pattern. There is an advantage that an abnormality of the hydraulic valve can be recognized.

[0006]

Next, one embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a traveling machine body of a tractor including a crawler traveling device 2, and a rear working machine 4 such as a rotary tiller is movably connected to a rear portion of the traveling machine body 1 via an elevating link mechanism 3. ing. Then, the rear working machine 4 includes the lift arm cylinder 5
While lifting and lowering is performed based on the vertical swing of the lift arm 6 associated with the expansion and contraction operation of the lift arm 6, the lift rod cylinder 7 that is interposed between the lift arm 6 and the elevating and lowering link mechanism 3 is tilted to the left and right. All of the basic configurations are the same as conventional ones.

Reference numeral 8 denotes a pair of left and right support arms pivotally supported on the front portion of the traveling machine body 1 so as to be vertically swingable. The front end portions of the support arms 8 are used to perform work such as leveling and leveling. Blade 9 is provided. And the blade 9
A lift operation (elevating operation) associated with the extension / contraction operation of the lift cylinder 10, an angle operation associated with the extension / contraction operation of the angle cylinder 11 (an operation of displacing either left or right of the blade 9 back and forth), and a tilt operation associated with the extension / contraction operation of the tilt cylinder 12. (Operation of displacing either left or right of the blade 9 up and down) or the like is possible, but since the blade 9 employed in the present embodiment has a plurality of holes 9a formed in proper places, the blade 9
The earth pressure acting on the cylinders can be released to reduce the working load on each of the cylinders 10 to 12.

Reference numeral 13 denotes a tilt sensor for detecting the tilt angle (left and right inclination angle) of the blade 9. The tilt sensor 13 is located substantially at the left-right center of the blade 9 and behind the upper end of the blade 9. It is arranged to do.
That is, since it is the position where the swaying width is the smallest and is not easily affected by the pressed soil, stable detection cannot be performed, and damage due to the effect of the pressed soil can be prevented. Since the hydraulic hoses of each of the cylinders 10 to 12 are piped from the right and left central portions of the blade 9 to the machine body side, the wiring of the tilt sensor 13 can be arranged along the hydraulic hoses.

Reference numeral 14 is a mast which is erected on the blade 9, and a light receiver 15 having a predetermined light receiving width in the vertical direction is provided at an upper end portion of the mast 14. on the other hand,
A light projector 16 for rotating and projecting a laser beam in a horizontal direction or an arbitrary tilt direction is installed at a predetermined location of a work site or a field, and the laser beam projected from the light projector 16 is received by the light receiver 15. In addition, the blade 9 with the laser light as a reference based on the detection of the height of light received by the light receiver 15
The height of the photodetector 15 is detected, that is, the absolute height is detected.
The vertical position can be freely adjusted with respect to the mast 14, and the control height (set height) of the blade control described later is changed based on the vertical position adjustment.

Reference numeral 17 denotes a pendulum body provided in the middle portion of the mast 14 so as to be swingable left and right.
Is overlapped with the mast 14 when the tilt angle (absolute right and left inclination angle) of the blade 9 is horizontal, while it swings left and right with respect to the mast 14 when the tilt angle is inclined left or right. By visually observing this, the tilt angle of the blade 9 can be easily confirmed.
Moreover, since the pendulum body 17 is supported by the mast 14 via the ball joint 17a, swinging in the front-rear direction is also allowed within a predetermined range. That is, when the mast 14 is tilted in the front-rear direction, it is possible to prevent a large moment load from being applied to the base end portion of the pendulum body 17.

A mast bracket 18 is integrally provided on the upper end of the central portion of the blade 9.
The mast 14 is detachably attached to a pipe 18a welded to the mast bracket 18 in the left-right direction using a pair of U-shaped bolts 19. And U
Since the front and rear inclination of the mast 14 is allowed when the character bolt 19 is loosened, the front and rear mounting angle of the mast 14 can be freely set, and the mast 14 can be attached to the pipe portion 4a of the rear working machine 4 described above. Then, the absolute height of the rear working machine 4 can also be detected.

Reference numeral 20 is a display provided near the driver's seat 21, and the display 20 displays the height of the blade 9 based on the laser light based on the detection signal input from the light receiver 15. It is something to do. That is, in the case where a plurality of light emitting display units 20a to 20e are arranged in parallel on the display surface of the display device 20 and the deviation amount with respect to the laser light is within the fourth area (for example, −5 mm to +5 mm). Is
The green light emitting display unit 20a located in the center of the display surface is operated to blink, and the deviation amount is within the third or fifth area (for example, -5 mm to -30 mm, +5 mm to +30 mm).
In the case of, the one of the yellow light emitting display portions 20b and 20c adjacent to the upper and lower sides of the green light emitting display portion 20a, which corresponds to the shift direction, is operated to blink, and the shift amount is within the second or sixth area. (For example, -30 mm to -95 m
m, +30 mm to +95 mm), one of the yellow light emitting display portions 20b and 20c corresponding to the shift direction is turned on, and the shift amount is outside the laser light detection range. Seven areas (for example, -9
5 mm or less, +95 mm or more), the LED light emitting display units 20d, 2 located at the upper and lower ends of the display surface.
Of 0e, one corresponding to the shift direction is configured to be turned on, but the detection signal of the light receiver 15 input to the display device 20 is a first control unit described later via a predetermined interface circuit. 22 is also input.

Reference numeral 23 denotes a side panel arranged on the side of the driver's seat 21, and a position lever 24 for raising and lowering the rear working machine 4 is arranged at a front portion of the side panel 23. On the other hand, in the rear part, an automatic plowing depth switch 2 for ON-OFF operation of the automatic plowing depth control described later is provided.
5. An operation tool such as an automatic tilt switch 26 for ON-OFF operation of automatic tilt control, which will be described later, and a tilt setting volume 27 for setting a target tilt of the automatic tilt control is covered by a transparent cover 28 which can be opened and closed. In the middle of the side panel 23, an elevating and lowering operation switch 29 for elevating and lowering the rear working unit 4 by a one-touch operation, and a knob that is larger than other operating tools are further provided. The plowing depth setting volume 30 is provided. And
The operation signal of each operation tool is input to the second control unit 31 that controls the rear working machine 4, but regarding the configuration and function of the side panel 23 described above, the actual operation flat 4-4242.
No. 5 gazette is used.

Reference numeral 32 denotes a blade operation panel. On the blade operation panel 32, a blade lift lever 33 for raising and lowering the blade 9 and a laser control (a blade control and a rotary laser control described later) are turned ON-O.
Laser automatic switch 34 for FF operation, first monitor lamp 34 incorporated in the laser automatic switch 34
a, a tilt automatic switch 35 for ON / OFF operation of tilt automatic control described later, and the tilt automatic switch 3
5 is provided with a second monitor lamp 35a incorporated therein, and operation tools such as a working machine changeover switch 36 for switching a laser control target (the blade 9 or the rear working machine 4). The first and second monitor lamps 34a are provided. , 35a
Is arranged near the rear of the blade lift lever 33, so that it can be easily viewed from the driver's seat 21 located laterally rear of the blade operation panel 32.

Numerals 37 to 40 are switches for performing the above-mentioned angle operation and tilt operation, and each switch 3
Since 7 to 40 are provided at the grip portion of the blade lift lever 33, the lift operation, the angle operation and the tilt operation of the blade 9 can be performed by the single blade lift lever 33.

Reference numeral 41 denotes a hydraulic valve assembly for operating the lift cylinder 10, the angle cylinder 11 and the tilt cylinder 12, and the hydraulic valve assembly 41
The switching valves 42, 43, 4 corresponding to each cylinder.
4, the positioner cylinders 42a, 43a, 44 are attached to the spools of the respective switching valves 42, 43, 44.
a is connected. And each positioner cylinder 4
2a, 43a, and 44a operate based on the switching of the electromagnetic valves 45 to 50 provided in the pilot operation oil passage to control the spool position, but the spool position of the lift cylinder switching valve 42 is changed. The dynamic transformer (differential transformer) 51 detects the detected signal and feeds back the detected signal to the first controller 22 via the differential transformer detection circuit and the A / D converter.

The second control section 31 is an existing one which is constructed by using a so-called microcomputer, but this one is based on the ground swing angle of the rear cover 4b and the plowing depth (ground level) of the rear working machine 4 is determined. Height sensor 54 for detecting the depth, an arm angle sensor 55 for detecting the vertical swing angle of the lift arm 6, a rod length sensor 56 for detecting the rod length of the lift rod cylinder 7, and a lateral tilt of the machine body. A signal is input from a tilt sensor 57 that detects the position of the lift lever, a position sensor 58 that detects the lever angle of the position lever 24, and further operation tools provided on the side panel 23. The operation signals of the cylinder 5, the lift rod cylinder 7, the automatic tilling depth monitor lamp 59 and the like are output. That is, in the second control unit 31, the position lever 24
Position control for controlling the rear working machine 4 up and down based on the detection signal of the arm angle sensor 42 (to control the height of the machine) so that the set working depth set by the working depth setting volume 30 is maintained. The plowing depth automatic control (ground height control) for automatically raising and lowering the rear working unit 4 based on the detection signal of the plowing depth sensor 41, and the inclination sensor for maintaining the set inclination set by the inclination setting volume 27. Based on the detection signal of 57, control such as automatic tilt control for automatically controlling the tilt of the rear working machine 4 is executed.

On the other hand, the first control unit 22 is also constructed by using a microcomputer, but this one has a lift angle for detecting the lift angle of the tilt angle sensor 13 and the light receiver 15 and the blade 9 described above. Signals are input from the sensor 60, the lever angle sensor 61 that detects the lever angle of the blade lift lever 33, the operation tools provided on the blade operation panel 32, and the lift cylinder 10 and the angle are determined based on these input signals. The operation signals of the cylinder 11, the tilt cylinder 12, etc. are output. That is, the first controller 22 controls the neutral reference value correction control for correcting the neutral reference value of the lift cylinder switching valve 42, the manual raising / lowering control for raising / lowering the blade based on the operation of the blade lift lever 33, the laser of the light receiver 15. Laser automatic control (absolute height control) that automatically raises and lowers the blade 9 to keep the detection height constant, and automatically moves the blade 9 based on the detection signal of the tilt angle sensor 13 to maintain the horizontal posture. Although the automatic tilt control for performing the tilt control is executed, as described above, the light receiver 15
Is mounted on the rear working machine 4 and the first control unit 22 is connected to the second control unit 31, the rear working machine 4 is automatically lifted and lowered by using the first control unit 22 and the second control unit 31 together. (Rotary laser control based on the detection signal of the light receiver 15,
Alternatively, it is possible to perform combined plunge depth control by using both rotary laser control and plowing depth automatic control).
The procedure of each control will be described based on a flowchart.

In the neutral reference value correction control, it is first judged whether or not the operation is started, and if the judgment is YES,
The spool position of the lift cylinder switching valve 42 is determined based on the detection signal of the operation transformer 51. And
When the spool position is within the proper range, the current detection value of the operating transformer 51 is set to the neutral reference value, while when the spool position is outside the proper range, the preset standard value is set to the neutral reference value. Is set to.
That is, paying attention to the fact that the spool is in the neutral position at the start of operation, the neutral reference value is corrected based on the spool position detection value at the start of operation, but the spool position detection value at the start of operation is improper (other than neutral). In this case, since the preset standard value is set as the neutral reference value, it is possible to prevent a detection value other than neutral from being erroneously set as the neutral reference value.

Further, in the neutral reference value correction control, when the spool position at the start of operation is proper, the first monitor lamp 34a is turned on in the first pattern while the spool position is not proper. In the above, the first monitor lamp 34a is operated to light in the second pattern. Therefore, it is possible to recognize that the neutral reference value has been corrected based on the lighting of the lamp in the first pattern.
The abnormality of the lift cylinder switching valve 42 can be recognized based on the lighting of the second pattern lamp.

In the manual elevating control, the operation angle of the blade lift lever 33 is set to which operation area (U1 to U3, D1 to D1).
D3 or dead zone). Then, in the case of the operation area U1 (rear and small operation angle), the blade 9 is raised at a low speed, and in the operation area U2 (rear and inside the operation angle), the blade 9 is raised at a medium speed,
In the case of (rear and large operation angle), the blade 9 is raised at high speed,
In the operation area D1 (front and small operation angle), the blade 9 is lowered at a low speed, in the operation area D2 (forward and operation angle is small), the blade 9 is lowered at a medium speed, and in the operation area D3 (front and large operation angle). In such a case, the blade 9 is subjected to processing such as high-speed lowering, but the operating area is set so that the range becomes narrower as the operating angle increases. That is, since the low-speed operation area is widened, delicate operation can be facilitated, or the possibility that the blade 9 operates at high speed when the blade lift lever 33 is accidentally moved is reduced as much as possible. ing.

In the automatic laser control (blade), it is determined which area includes the above-mentioned laser light detection area. Then, in the first area, the blade 9 rises at a high speed, in the second area, the blade 9 rises at a medium speed, in the third area, the blade 9 rises at a low speed, and in the fourth area, the blade 9 moves up and down. Stop the blade 9 in the fifth area at a low speed, and in the sixth area, the blade 9
Is performed at a medium speed, and in the case of the seventh area, the blade 9 is lowered at a high speed, but in the case of the first area or the seventh area, it passes through the adjacent area (second area or sixth area). It is determined whether or not it has been done, and if the determination is NO, the lifting operation of the blade 9 is stopped. That is, when the laser light detected in the middle portion of the light receiver 15 suddenly disappears without being vertically displaced, it is determined that the laser light is blocked by an obstacle or the projector / receiver has a failure, and the blade The lifting and lowering operation of 9 is stopped.

On the other hand, when it is judged that the blade 9 has passed through the adjacent area (the second area or the sixth area), the blade 9 is raised or lowered at a high speed, but the predetermined time T1 has passed (or some place). If the second area to the sixth area do not move even after a fixed amount of movement), the raising / lowering operation of the blade 9 is stopped. That is, when the light receiver 15 does not receive the laser beam even when the blade 9 is moved up and down at a high speed, it is determined that some trouble has occurred, and the lifting operation of the blade 9 is stopped.

Further, in the automatic laser control, if it is determined that the area is the third area or the fifth area, whether or not the fifth area is transferred to the third area without passing through the fourth area, or From the fourth area to the fifth area without passing through the fourth area, the judgment is Y
In the case of ES, the raising / lowering operation of the blade 9 is stopped for a predetermined time T2. That is, the light receiver 15
If the detection position of fluctuates within a very small range across the fourth area, the lift cylinder operation may be delayed and so-called hunting may occur. It is supposed to stabilize.

In the automatic tilt control, first, it is judged whether the tilt switches 39 and 40 are OFF. If the judgment is NO, the tilt cylinder 12 is operated in the corresponding direction, and if the judgment is YES. Is the tilt sensor 1
The tilt cylinder 12 is automatically operated based on the detected angle of 3. However, when the tilt cylinder 12 is automatically controlled, the laser automatic control is ON and the light receiver 1
When the detection area 5 is the seventh area, the control flow rate of the tilt cylinder 12 is reduced to slowly perform the tilting operation of the blade 9. That is, in the state where the blade 9 is located in the work area (first to sixth areas), the tilting operation is quickly performed to give priority to the control accuracy, while the blade 9 is raised in the non-work area (seventh area).
In the state of being located at, the tilting operation is performed slowly to give priority to the stability of the airframe.

On the other hand, in the mode switching control executed when the photodetector 15 is mounted on the rear working machine 4, is the laser automatic switch 34 turned ON and the working machine switching switch 36 set to the rear working machine position? If both determinations are YES, it is further determined whether the plowing depth automatic switch 25 is ON or OFF. When the automatic plowing depth switch 25 is OFF, the rotary laser control based on the detection signal of the light receiver 15 is executed, while when the automatic plowing depth switch 25 is ON, the rotary laser control and the plowing are performed. Combined tillage depth control is performed by using it in combination with deep automatic control. That is, since the rotary laser control and the compound plowing depth control are switched using the existing plowing depth automatic switch 25, it is not necessary to add a dedicated switch, or the switching operation is intuitively recognized. It becomes easy to do.

In the automatic plowing depth monitor control for controlling the automatic plowing depth monitor lamp 59, first, the control mode of the rear working machine 4 (rotary laser control, combined plowing depth control or existing automatic plowing depth control) is determined. At the same time, the automatic working depth monitor lamp 59 is turned on in a pattern (first to third) corresponding to the control mode. Therefore, the control mode of the rear work implement 4 can be easily recognized based on the lighting pattern of the automatic working depth monitoring lamp 59. However, the composite working depth control using the detection signal of the working depth sensor 54 or the existing working depth is used. When it is determined to be automatic control, it is further determined whether or not the working depth sensor 54 is in the connected state, and when the determination is NO, the working depth automatic monitor lamp 59 is set to the fourth pattern. The lighting operation is performed to notify that the tilling depth sensor 54 has been forgotten to be connected.

In the rotary laser control, first,
After confirming that the laser automatic switch 34 is ON and the work implement switch 36 is set to the rear work implement position, a work start flag (default is set state)
It is determined whether or not it is the start of work based on. And
If this determination is YES, it is determined whether or not the detection value of the position sensor 58 and the detection value of the arm angle sensor 55 match, and the height of the rear working unit 4 (light receiver 15) is detected by the laser beam. It is determined whether or not it is within the range, and the automatic lifting control of the rear work implement 4 is restricted until both determinations are YES. That is, at the beginning of the work, the position work lever 24 is required to lower the rear work implement 4, and the automatic raising / lowering control is executed from the time when the photodetector 15 detects the laser beam. The rear working machine 4 can be prevented from moving up and down based on the control.

If both of the above judgments are YES, the work start flag is reset and the rear working machine 4 is automatically lifted and lowered based on the laser light. When 24 is operated, the above-mentioned position control is executed in preference to the automatic raising / lowering control, and when the laser light detection area enters the seventh area based on the raising operation of the position lever 24,
The work start flag is set when it is judged that the work is interrupted due to the turning of the machine body or the like.

In the configuration as described above, the spool position of the lift cylinder switching valve 42 is detected by the operating transformer 51, and the spool position is feedback-controlled based on the detected value.
The spool position of the lift cylinder switching valve 42 is determined based on the detection signal of the operating transformer 51, and if the spool position is within the proper range, the current detected value of the operating transformer 51 is set to the neutral reference value. If the spool position is out of the proper range, the preset standard value is set as the neutral reference value. That is, focusing on the fact that the spool is in the neutral position at the start of operation, the neutral reference value is corrected based on the spool position detection value at the start of operation, but the spool position detection value at the start of operation is improper (other than neutral). In this case, the preset standard value is set to the neutral reference value, so it is possible to prevent detection values other than neutral from being set incorrectly to the neutral reference value. It is possible to avoid the inconvenience that the control is executed based on

In addition, when the spool position at the start of operation is proper, the first monitor lamp 34a is turned on in the first pattern, while when the spool position is incorrect, the first monitor lamp 34a is activated. Since the lighting operation is performed in the second pattern, it is possible to recognize that the neutral reference value has been corrected based on the lighting of the first pattern of the lamp, while the abnormality of the lift cylinder switching valve 42 is detected based on the lighting of the second pattern of the lamp. There is an advantage that can be recognized.

When the light receiver 15 is mounted on the rear working machine 4 and laser control is executed, the laser automatic switch 34 is turned on and the working machine changeover switch 36 is set to the rear working machine position. , Plowing depth automatic switch 25
Is OFF, the rotary laser control based on the detection signal of the light receiver 15 is executed, while when the plowing depth automatic switch 25 is ON, the rotary laser control and the plowing depth automatic control are used in combination. Combined tilling depth control will be executed. That is, since the switch between the rotary laser control and the compound plowing depth control is performed by using the existing automatic plowing depth switch 25, it is not necessary to add a dedicated switch, or the shifting operation is intuitively recognized. It is easy to operate and can contribute to improvement of operability.

In executing the rotary laser control, at the beginning of the work, the position lever 24 is required to lower the rear work implement 4, and the automatic light-emission control is started from the time when the light receiver 15 detects the laser beam. Therefore, it is possible to prevent the rear working unit 4 from moving up and down based on the automatic lifting control at the same time when the engine is started, and the laser light detection area enters the seventh area based on the lifting operation of the position lever 24. In this case, since the work start flag is set when it is judged that the work is interrupted due to the turning of the machine body, the rotary laser control can be interrupted only by raising the position lever 24, while the position lever 24 is lowered to the work position. There is an advantage that the rotary laser control can be restarted only by operating.

[Brief description of drawings]

FIG. 1 is a side view of a tractor.

FIG. 2 is a plan view of the same.

FIG. 3 is a perspective view of a main part of a blade.

FIG. 4 is a perspective view of a main part of a rear working machine.

FIG. 5 is a front view of the tractor showing the action of the pendulum body (tilt horizontal state).

FIG. 6 is a front view of the tractor showing the action of the pendulum body (tilt upper left position).

FIG. 7 is a front view of a pendulum body.

FIG. 8 is a partially cutaway side view of the same.

FIG. 9 is a perspective view of a display device.

FIG. 10 is a perspective view showing a side panel and a blade operation panel.

FIG. 11 is a plan view of a blade operation panel.

FIG. 12 is a side view of the same.

FIG. 13 is a hydraulic circuit diagram of a hydraulic valve assembly.

FIG. 14 is a block diagram showing inputs and outputs of first and second control units.

FIG. 15 is a flowchart of neutral reference value correction control.

FIG. 16 is a flowchart of manual lifting control.

FIG. 17 is a flowchart of laser automatic control.

FIG. 18 is a flowchart of tilt automatic control.

FIG. 19 is a flowchart of mode switching control.

FIG. 20 is a flow chart of automatic plowing depth monitor control.

FIG. 21 is a flowchart of rotary laser control.

[Explanation of symbols]

 1 Traveling Machine Body 4 Rear Working Machine 9 Blade 15 Light Receiver 16 Projector 22 First Control Section 32 Second Control Section 41 Hydraulic Valve Assembly 42 Lift Cylinder Switching Valve 42a Positioner Cylinder 51 Differential Transformer

Claims (2)

[Claims] 1. A hydraulic control device for detecting a spool position of a hydraulic valve with a sensor, and feedback-controlling the spool position based on a detection value of the sensor, wherein the hydraulic control device sets a spool position at the start of operation. Judging based on the detection value of the sensor, if the judgment position is appropriate, while setting the current sensor value to the neutral reference value,
A hydraulic control device provided with a neutral reference value setting means for setting a preset standard value to the neutral reference value when the determination position is inappropriate. 2. The hydraulic control device according to claim 1, when the judgment position is appropriate, the predetermined notification device is operated in the first pattern, while when the judgment position is incorrect,
A hydraulic control device provided with spool position notification means for operating the notification device in a second pattern.