JP2879264B2 - Loader control device - 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 a loader such as a front loader mounted on a front part of a traveling machine such as a tractor for loading or excavating, backfilling, leveling a field, or removing snow from compost or hay.

[0002]

2. Description of the Related Art In a hydraulic circuit for controlling the operation of a loader of this type, a pilot-opellet type poppet valve is provided in a hydraulic supply line of a switching valve for adjusting the inclination and height of a bucket or a lift arm of the loader. There is a means using a closed center type constant pressure hydraulic circuit.

[0003]

However, in such a closed center type constant pressure type hydraulic circuit, if the pilot oil is constantly flowing in order to operate the poppet valve, the engine rotation speed is reduced. When the number becomes idling and the pump discharge amount decreases, the main circuit also has a shortcoming such that the flow rate becomes insufficient and cavitation occurs, and in the worst case, seizure occurs in the valve.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a closed center type constant pressure type hydraulic circuit for controlling the operation of a loader mounted on an airframe, wherein a poppet valve is provided in a hydraulic supply line of the closed center type hydraulic circuit. The shut-off valve for shutting off the supply of the hydraulic pressure is provided, and the opening of the shut-off valve is controlled only when the poppet valve is operated.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. 1 is a hydraulic circuit diagram of the front loader, FIG. 2 is a side view of the whole, FIG. 3 is a side view of the front loader, in which (1) is a tractor as a traveling body, and (2) and (3) are tractors ( 1) front and rear wheels, (4) a chassis that is a machine base on which the front wheels (2) are mounted, (5) an engine mounted on the chassis (4), and (6) connected to the engine (5). A power transmission case in which the rear wheel (3) is mounted, (7) is a driver's seat mounted on the rear upper surface of the case (6), (8) is a steering handle, and is an attachment of a front loader (9). A bucket (10) is mounted in front of the tractor (1) via a pair of left and right lift arms (11).
In the drawing, (12) is a rear mounting frame for supporting the lift arm (11), (13) is a horizontal mounting frame for integrally connecting the rear end to the rear mounting frame (12),
(14) is a front mounting frame integrally connected to the front end side of the horizontal mounting frame (13).
(13) A base stand (15) which is formed in a gate shape when viewed from the side and is fixed to the lower surface side of the power transmission case (6).
To the rear mounting frame (1) via the rear mounting base (16).
2) and a front mounting frame (14) on the front end side of the chassis (4) via a front mounting base (17), and gates on both sides of a hood (18) covering the engine (5). The frames (12), (13), and (14) of the shape are mounted symmetrically.

Further, the lift arm (1) is connected to the upper end of the front mounting frame (12) via a pivot pin (19).
A lifting member which connects and supports the base end of 1) and which is provided between the frame (12) and the fixed locking plate (20) in the middle of the lift arm (11) via pins (21) and (22). A loader elevating cylinder (23) is interposed, and the lift arm (11) is appropriately raised and lowered by the expansion and contraction operation of the cylinder (23).

A fixed bracket (24) (2) which is a fixed mounting plate between the middle and the front end of the lift arm (11).
5) support the base ends of the dump cylinder (28) and the dump arm (29) via the swinging pins (26) (27), and connect these cylinder (28) and the tip of the arm (29) to the pin ( 30), and the tip of the arm (29) is linked to the rear upper end of the bucket (10) via a pin (31), an upper hook arm (32) and a dump link (33). I have. Then, the lower rear end of the bucket (10) is connected to the lift arm (1).
1) The front end is supported via a pin (34) and a lower hook arm (35), and the tilt of the bucket (10) is appropriately changed by the expansion and contraction operation of the dump cylinder (28).

Further, a notch (3) having an obliquely upward opening is provided on the intermediate front side of the rear mounting base (16) via a hook arm (36).
7), a horizontal opening notch (38) is formed at the front upper end of the rear mounting base (16), and a pair of leg plates (39) (39) are integrally formed at the lower end of the rear mounting frame (12). The open legs (40) and (40) are formed at the lower ends of the leg plates (39) and (39), and are engaged with the notches (37) and (38). The locking pins (41) and (42) are integrally and horizontally fixed between the leg plates (39) and (39).

After the pin (41) is engaged with the notch (37) by the guide of the hook arm (36), the rear mounting frame (12) is displaced around the pin (41) to displace the notch (38). A pin (42) is engaged with the left and right mounting bases (16) (1) at the rear of the tractor (1).
6), the left and right rear mounting frames (12), whose upper ends are connected by a connecting pipe (43) from the front upper side, are configured to be engaged and fixed so as to be tiltable and disengageable only forward. .

Further, the left and right front mounting frames (14).
(14) A holding rod (44) which is a lock pin between lower ends.
And a rectangular tubular holding box (45) is integrally formed on the front mounting base (17), and the cam member (46) is detachably engaged with the box (45). 45) The rod-shaped body (44) is engaged with the cam member (46) from the lower side into the downward notch on the lower surface, and the front mounting frame (14) is engaged with the front mounting base (17) from the lower side. It is configured to be fixed together.

Further, as shown in FIGS. 2, 5 and 6,
A controller (47) for controlling the operation of the cylinders (23) and (28) is provided on the right side of the driver's seat (7) with a support arm (4).
The joystick type manual lever (4) which can be freely attached and detached via
9) and a neutral return type one-touch lever (50) that automatically raises and lowers the lift arm (11) to a set height.
A variable resistor type lift arm lower limit setting volume (51) for setting the automatic lowering height of the lift arm (11);
One-touch changeover switch (52) for turning on / off automatic raising / lowering control of one-touch lever (50), and turning on / off horizontal grounding control for making bucket (10) parallel to tractor (1) near the ground by lowering of lift arm (11). A horizontal ground switch (53), a bucket setting volume (54) for adjusting a horizontal (parallel) state of the bucket (10) with respect to the tractor (1) body, and the support arm (4).
8) a controller detachment switch (55) for detecting the attachment / detachment of the controller (47) to / from the controller (47) and the manual lever (4).
A lift arm potentiometer (56) for raising and lowering which is linked with the forward and backward tilting of (9), and a lock type floating switch () provided near the manual lever (49) to lower the lift arm (11) by its own weight at the time of lowering operation. 5
7) and a bucket pot for dumping and scooping (58) interlocked with the left and right inclination of the manual lever (49).
And an up / down switch (59) operated by the one-touch lever (50) for switching operation are provided in the controller (47).

Further, as shown in FIG. 7, a loader control circuit (60) constituted by a microcomputer is provided in the controller (47), and each of the volume (51) (5)
4), each switch (52) (53) (55) (57)
(59) and a potentiometer switch (61) for connecting the potentiometers (56) and (58) to the circuit (60) and applying a drive power to the circuit (60). (62), fuse (63)
The switch (61) is connected to the battery (64) via the like.
To connect.

A variable stroke capacitance lift arm position sensor (65) mounted in parallel to the loader lifting cylinder (23) via the pins (21) and (22), and via the pins (26) and (30). Dump cylinder (28)
And a variable stroke capacitance type bucket position sensor (66) mounted in parallel with the lift arm (11) and the supporting height of the bucket (10) by the sensors (65) and (66) connected to the circuit (60). A lift arm raising electromagnetic solenoid (67) and a lift arm lowering electromagnetic solenoid (68) for extending and retracting the loader elevating cylinder (23), and a bucket dump electromagnetic solenoid (68) for extending and retracting the dump cylinder (28). 69) and bucket rake electromagnetic solenoid (7
0), and each of the solenoids (67) to (70) is connected to the control circuit (60) for output.

A light emitting diode (71) for indicating runaway of the control circuit (60) by turning off the light is provided, and each volume (51) (54) and each potential (56) are provided.
(58) and the abnormal input of each sensor (65) (66) are displayed by lighting of the light emitting diode (71),
The normal state of each part is displayed by blinking the light emitting diode (71).

Further, as shown in FIG. 1, a closed center type constant pressure hydraulic circuit (72) for controlling the operation of the front loader (9) is provided. 73)
A dump rake valve (74) for controlling the operation of the dump cylinder (28) is provided, and high-pressure oil of the hydraulic pump (75) is supplied to each cylinder (23) via each valve (73) (74).
(28), and each valve (73) (7
4) Pilot operation cylinder (76) for switching operation
(77) and each solenoid (67) (68) (69)
Switching control by (70), each operating cylinder (76)
Pilot operated valves (78), (79), (8) for raising and lowering and dumping and rake actuating (77)
0) and (81), and the loader control circuit (6
0) pulse signal output of each solenoid (67)-
Each of the operation valves (78) to (81) is switched by pulse control for operating (70), and each of the operation cylinders (76) is switched.
(77) is operated to switch each control valve (73) (74), and each cylinder (23) (28) is operated, thereby lowering the front loader (9) and dumping while lowering. And a dumping operation performed at a constant height, a dumping operation while ascending, a lifting operation, a scooping operation while ascending, a scooping operation at a constant height, and a scooping operation while descending. It is configured to do so.

A constant-pressure poppet valve (82) is interposed in the main hydraulic supply line (72a) of the hydraulic circuit (72), while a constant-pressure poppet valve (82) is always provided in front of the hydraulic supply inlet of the hydraulic circuit (72). Is a solenoid (8
3) An operation type 2-port 2-position shut-off valve (84) is provided, this solenoid (83) is connected to the control circuit (60) for output, and the solenoid (67) to (70) is energized by the solenoids. (73) Only when the (74) is switched from the neutral position and the poppet valve (82) is in the open start state, the solenoid (83) is excited to open the shut-off valve (84). Poppet valve (8
It is configured not to supply pilot oil for operating 2) to the hydraulic circuit (72).

This embodiment is configured as described above, and FIG.
9 is a flowchart showing a check operation. When the power switch (61) is turned on and the loader control circuit (60) runs away, the light emitting diode (71) is turned off. When there is an abnormality in the check, the light emitting diode (71) is turned on, and the LED (71) blinks when the respective parts are in a normal state. Is displayed.

FIG. 9 shows a bucket potentiometer (58).
It is a flowchart showing a check, when the input from the bucket potentiometer (58) is too large or too small than the dump or rake control range, the light emitting diode (71)
Is turned on to indicate an abnormal input, and the bucket potentiometer (5) operated by the manual lever (49) is turned on.
8) Bucket (10) manual operation based on input is prohibited.

FIG. 10 shows a bucket position sensor (6
6) is a flowchart showing a check. When the input from the bucket position sensor (66) is larger or smaller than the dump or rake control range, the light emitting diode (71) is used.
Is turned on to display an abnormal input, and the input from the bucket position sensor (66), the horizontal grounding operation shown in FIG. 18, and the parallel operation shown in FIG. 19 are prohibited, and the dump cylinder (28) is operated. Bucket (1) until the bucket position sensor (66) input is within the proper input range.
0) is automatically returned, and the prohibitions are released.

FIG. 11 is a flow chart showing a check of the lift arm potentiometer (56). When the input from the lift arm potentiometer (56) is larger or smaller than the range of raising or lowering the light emitting diode (7).
1) is turned on to display the abnormal input, and the manual operation of the lift arm (11) based on the input of the lift arm potentiometer (56) operated by the manual lever (49) is prohibited.

FIG. 12 is a flow chart showing the check of the lift arm position sensor (65). When the input from the lift arm position sensor (65) is larger or smaller than the range of control for raising or lowering the light emitting diode (7).
1) lights up to display an abnormal input, and inhibits input from the lift arm position sensor (65), horizontal grounding operation shown in FIG. 18, parallel operation shown in FIG. 19, and one-touch operation shown in FIG. 17, respectively. Then, the loader elevating cylinder (23) is operated to operate the lift arm position sensor (65).
The lift arm (11) is automatically returned until the input is within the proper input range, and the prohibitions are released.

FIG. 13 is a flowchart showing the check of the lower limit setting volume (51) of the lift arm.
When the input from the lift arm lower limit setting volume (51) is larger or smaller than the range of raising or lowering control, the light emitting diode (71) is turned on to display an abnormal input, and the lower limit of the lift arm lower limit setting volume (51) is displayed. A value intermediate between the set value and the maximum set value is automatically set as an input of the volume (51), and the output of the volume (51) is fixed to a neutral state.
Is returned to an intermediate position between the neutral position and the lowest position in the elevating range.

FIG. 14 is a flow chart showing the check of the bucket setting volume (54). When the input from the bucket setting volume (54) is larger or smaller than the dump or rake control range, the light emitting diode (71) is turned on. In addition to displaying the abnormal input, the intermediate value between the minimum set value and the maximum set value of the bucket setting volume (54) is automatically set as the input of the volume (54), and the output of the volume (54) is set to neutral. In a fixed state, the bucket (10) is returned to the dumping posture and supported.

FIG. 15 is a flowchart showing the manual operation of the bucket (10). When the manual lever (49) is dumped or scooped, the manual lever (49) is operated.
Solenoid (72) (7) in proportion to the difference between the bucket potentiometer (58) input interlocked with
3) The duty ratio of the dump or rake control pulse signal for driving is changed, and the speed of the dump cylinder (28) is controlled by adjusting the hydraulic flow rate by the pulse signal control. As the operation amount of the manual lever (49) increases, the cylinder ( 28) Pulse control (1)
0), a bucket potentiometer (58) input and a bucket position sensor (6).
6) Immediately before the bucket (10) stop position where the input matches, a cushion operation for gradually reducing the driving speed of the cylinder (28) is performed by pulse control, and the bucket (10) is stopped at a predetermined position.

FIG. 16 is a flowchart showing the manual operation of the lift arm (11).
9) When the lowering or raising operation is performed, the manual lever (4
9) and the solenoid (6) in proportion to the difference between the input of the lift arm potentiometer (56) and the value of this neutral position.
7) The duty ratio of the lowering or raising control pulse signal for driving (68) is changed, and the speed of the loader lifting cylinder (23) is controlled by adjusting the hydraulic flow rate by pulse signal control. The lift or lowering operation of the lift arm (11) is performed by pulse control that makes the operation of the cylinder (23) faster as the size is larger.
Lift arm (11) whose lift arm potentiometer (56) input matches lift arm position sensor (65) input
A cushion operation for gradually reducing the driving speed of the cylinder (23) is performed by pulse control just before the stop position, and the lift arm (11) is stopped at a predetermined height position.

FIG. 17 is a flowchart showing a one-touch operation for automatically raising and lowering the lift arm (11) to the set height.
5) is ON to confirm the mounting of the controller (47), and in a state where the one-touch switch (52) is ON, the one-touch lever (50) is operated to raise and lower, and the raising and lowering switch (59) is raised or lowered. The lift arm (11) is automatically raised or lowered when it is switched to the lower limit. The lower limit of the lift arm lower limit setting volume (51) can be set to any height by lowering the one-touch lever (50). The lift arm (11) is moved up and down to the position by the speed control of the pulse control, while the lifting operation of the one-touch lever (50) moves the lift arm (11) to the fixed lifting position at a predetermined fixed height by the speed control of the pulse control. The arm (11) is moved up and down, and a cushioning operation that gradually decelerates before a predetermined stop position is pulsed. Notwithstanding et al lift arm done in your (1
1) is stopped, and the lift arm (11) is automatically raised and lowered to a lower limit setting position of the volume (51) or a fixed lifting position at a fixed height to support the same.

When the switches (52) and (55) are turned off, the one-touch operation is immediately stopped to stop the output, and when the power switch (61) is turned on from off, the one-touch operation is stopped. Even if the condition is satisfied, the one-touch operation is not performed. In this case, the operation condition is not satisfied, and the one-touch operation is performed by satisfying the operation condition again.

FIG. 18 is a flow chart showing a horizontal grounding operation for supporting the bucket (10) in a predetermined posture (parallel) with respect to the tractor (1) machine, wherein the controller grounding switch (55) is turned on and the horizontal grounding switch is turned on. (53)
Is turned on, the manual operation shown in FIG.
The bucket setting volume which adjusts the horizontal (parallel) state of the bucket (10) with respect to the body by not lowering the lift arm (11) by the one-touch operation of FIG. (5
4) The set value of 4) is input, and the bucket (10) is controlled to the horizontal grounding posture in cooperation with the lowering of the lift arm (11) based on the input of the volume (54) and the input of each sensor (65) (66). The tractor (1) is lowered while supporting the bucket (10) in a constant posture with respect to the body of the tractor (1).
The dump cylinder (28) is operated at the higher of the control speed proportional to the lowering speed of the lift arm (11) and the step driving speed of the ideal value, and either the calculation speed based on the speed of the lift arm (11) or the set speed is used. The bucket (10) is moved to the horizontal grounding posture by the quicker one, and even if the lift arm (11) descends and reaches a predetermined position, the bucket (10) is positioned on the rake side and is in the horizontal grounding posture. If not, the lowering of the lift arm (11) is stopped, the horizontal contact attitude control of the bucket (10) is continued, and only the horizontal contact operation of the bucket (10) is performed.
When the bucket (10) becomes horizontal (parallel),
The lowering operation of the lift arm (11) is started by the manual lowering operation shown in FIG. 16, and while the lowering of the lift arm (11) is performed, the bucket (10) is controlled to a horizontal contact position, and the cushion is gradually decelerated to a predetermined position to lift the lift. The arm (11) is stopped, and the bucket (10) is supported in a horizontal posture. The horizontal grounding is stopped by the manual operation of the bucket in FIG. 15, the horizontal grounding is resumed by the manual release, and the lift arm (11) of FIG.
When the manual ascent operation is performed, the horizontal grounding operation is stopped, and the parallel operation shown in FIG. 19 is controlled. When one of the switches (53) and (55) is turned off, the horizontal grounding operation is stopped after controlling the bucket (10) to the neutral posture.

FIG. 19 is a flow chart showing a parallel operation for raising and lowering the bucket (10) in a substantially constant posture. When the controller detachable switch (55) is turned on, FIG.
By lifting and lowering the lift arm (11) by the manual operation of FIG. 6 or the one-touch operation of FIG. 17, immediately before the lift arm (11) is raised or lowered in a state where the bucket (10) of FIG. Of the bucket (10) with respect to the tractor (1) or the position of the bucket (10) immediately after stopping when the bucket (10) is operated while the lift arm (11) is moving up and down. The speed of the dump cylinder (28) for operating the bucket (10) is changed by pulse control in proportion to the elevating speed of the lift arm (11), and the scooping speed is compared with the dump speed of the bucket (10). And the lift arm (11) is stopped at a predetermined position by a cushion operation of gradually decelerating. The parallel operation is stopped by the manual operation of the bucket in FIG. 15, and the parallel operation is resumed by the manual release. When the switch (55) is turned off during the parallel operation, the bucket (10) is moved to the ideal position. After that, the parallel motion is stopped after being supported in the neutral posture.

FIG. 20 shows each solenoid (67)-
FIG. 20 is a flowchart showing a continuous operation restriction for restricting the operation of (70) and preventing the power supply circuits from being thermally destroyed, wherein the same operation of FIG. 15 to FIG. Has elapsed, the lift arm (1
1) and the control output of the bucket (10) are stopped, the power supply circuits of the solenoids (67) to (70) are turned off, and all the loader control circuits (60) are reset. Control is resumed by continuous operation (pulse signal output OFF), and when a certain period of time elapses, each solenoid (67) to (70) is operated by a pulse signal to adjust the control speed of the cylinders (23) and (28); Each operation of FIGS. 15 to 19 is performed.

FIGS. 21 to 23 are flow charts showing a floating operation for freely lowering the lift arm (11) by its own weight. The floating switch (57) and the horizontal grounding switch (53) are turned on and the manual lever ( 49) lift arm potentiometer (5
When the lift arm (11) is lowered by operating 6), the lift arm (11) is lowered by the horizontal grounding operation shown in FIG. 18, and the lift arm position sensor (65) detects that the lift arm (11) is below a certain height. At this time, the descending solenoid (68) is operated continuously, and the elevating control valve (73) is continuously driven to the descending side to enter the floating operation. When the switches (57) and (53) are on and the one-touch changeover switch (52) is on and a one-touch lowering operation is performed, the lowering is performed by the one-touch and horizontal grounding operation shown in FIGS. 17 and 18, and the lift arm position sensor ( When the state (65) detects that the lift arm (11) is below a certain height, the descending solenoid (68) is continuously operated to continuously drive the elevating control valve (73) to the descending side, and the floating operation is performed. I have.

On the other hand, when the floating switch (57) is on, the horizontal grounding switch (53) is off, and the lift arm (11) is lowered by operating the lift arm potentiometer (56) by the manual lever (49). ,
When the lift arm is lowered by manual operation of the lift arm shown in FIG. 16 and the position sensor (65) is in a state where the height of the lift arm (11) is detected below a certain height, the valve (73) is continuously driven to the lower side as described above. Enter floating operation. When the floating switch (57) is on, the horizontal ground switch (53) is off, and the one-touch switch (5
When 2) is on and a one-touch descent operation is performed, FIG.
Of the position sensor (6)
When 5) detects a state in which the height of the lift arm 11 is equal to or less than a certain height, the operation enters the floating operation as described above.

During such a floating operation, the manual lever (49) or the one-touch lever (5)
0), when the lift arm (11) is operated to the ascending side, this ascending operation is given priority.
When the height is detected to be equal to or less than the predetermined height, the operation enters the floating operation. When the bucket (10) is manually operated during such a floating operation, the control valve (73) of the lift arm (11) is continuously driven downward and the bucket valve (74) is operated. Driving is also performed. In the horizontal grounding operation in a state where the lift arm position sensor (65) detects the height of the lift arm (11) below a certain height, the target value on the assumption that the detection value of the position sensor (65) is fixed is assumed. The operation of the bucket (10) is controlled by the value.

That is, this operation is canceled by a manual ascent operation or an automatic ascent operation, even if the floating switch (57) is turned off or the floating switch (57) is kept on, and the height exceeds the set height. Sometimes, the floating operation is not canceled even if the height of the arm (11) exceeds the set height due to an external factor due to a floating state. Also, the scooping and dumping operation by the manual lever (49) can be performed even during the floating operation. Further, when the floating operation starts during the horizontal grounding operation, the bucket (10) angle calculated from the angle of the arm (11) is not operated as in the normal horizontal grounding operation, but the bucket (10) angle is set. Make it work. This is the arm (1
This is because the angle of the bucket (10) is constantly changed due to the free movement of 1), thereby preventing a hunting state from occurring.

FIG. 24 further shows each valve (73).
16 is a flowchart for energizing the solenoid (83) to open the shut-off valve (84) only while (74) is operated by pulse control, and the bucket manual operation of FIG. 15 and the lift arm manual operation of FIG. 17, one-touch operation of FIG. 17, horizontal grounding operation of FIG. 18, and parallel operation of FIG.
When the poppet valve (82) is turned on when any one of 7) to (70) is excited and the operation of the valve (73) or (74) is started, the solenoid (83) of the shut-off valve (84) is excited. Then, while the poppet valve (82) is driven to open, the shut valve (84) is controlled to open.
When the poppet valve (82) is closed after this operation is completed, that is, when the pulse operation signal for the solenoids (67) to (70) is stopped, the shutoff valve (84) after a certain off delay time (T) as shown in FIG. Solenoid (8
3) The excitation for the hydraulic circuit (72) is released.
The supply of hydraulic pressure to the valve is shut off by the shut-off valve (84). In this case, a minute on-delay time may be provided to the shut-off valve (84).

[0036]

As is clear from the above embodiments, the present invention provides a hydraulic pressure supply line (72a) of a closed center type constant pressure hydraulic circuit (72) for controlling the operation of a loader (9) mounted on an airframe. And a shut-off valve (84) for shutting off hydraulic pressure supply to the hydraulic circuit (72), wherein the poppet valve (82) is provided.
Since the shut-off valve (84) is controlled to be opened only when the valve (84) is operated, the shut-off valve (84) is controlled only when the poppet valve (82) that needs to drive various hydraulic operating units is opened.
The hydraulic drive work can be performed by opening the hydraulic pump, so that the hydraulic pump (75) or the hydraulic circuit (72) is not damaged by the continuous supply of the hydraulic pressure to the hydraulic circuit (72) as in the related art. It has remarkable effects such as prevention.

[Brief description of the drawings]

FIG. 1 is a loader hydraulic circuit diagram.

FIG. 2 is an overall side view.

FIG. 3 is a side view of the loader.

FIG. 4 is a plan view of the loader.

FIG. 5 is a front view of the controller.

FIG. 6 is a side view of the controller.

FIG. 7 is an electric control circuit diagram of the loader.

FIG. 8 is a flowchart.

FIG. 9 is a flowchart.

FIG. 10 is a flowchart.

FIG. 11 is a flowchart.

FIG. 12 is a flowchart.

FIG. 13 is a flowchart.

FIG. 14 is a flowchart.

FIG. 15 is a flowchart.

FIG. 16 is a flowchart.

FIG. 17 is a flowchart.

FIG. 18 is a flowchart.

FIG. 19 is a flowchart.

FIG. 20 is a flowchart.

FIG. 21 is a flowchart.

FIG. 22 is a flowchart.

FIG. 23 is a flowchart.

FIG. 24 is a flowchart.

FIG. 25 is a time chart.

[Explanation of symbols]

 (9) Loader (72) Hydraulic circuit (72a) Hydraulic supply line (82) Poppet valve (84) Shut valve

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Shibata 2-181-1, Inaji, Amagasaki City, Hyogo Prefecture Inside Kanzaki High-Tech Koki Works Ltd. (72) Inventor Kazumasa Kitagawa Inaji, Amagasaki City, Hyogo Prefecture No. 2-18-1 Kanzaki High-Tech Koki Manufacturing Co., Ltd. (56) References JP-A-2-243835 (JP, A) JP-A-2-300502 (JP, A) JP-A-3-244718 (JP) , A) (58) Field surveyed (Int.Cl. ⁶ , DB name) E02F 3/43

Claims (1)

(57) [Claims] In a structure in which a poppet valve is provided in a hydraulic supply line of a closed-center constant-pressure hydraulic circuit that controls the operation of a loader mounted on an airframe, a shut-off valve that shuts off hydraulic supply to the hydraulic circuit is provided. A control device for the loader, wherein the shut-off valve is controlled to be opened only when the poppet valve is operated.