Hydraulic system for working machine and control method of the hydraulic system

1. A hydraulic system for a working machine, comprising:

a boom cylinder to move a boom upward and downward;

a working tool cylinder to move a working tool attached to the boom;

a boom control valve to control the boom cylinder;

a working tool control valve to control the working tool cylinder;

a horizontal control valve including a switching valve having:

an activating position to allow a horizontalizing operation of the working tool; and

a stopping position to stop the horizontalizing operation; and

a controller device having:

a first information obtaining portion to obtain permission and non-permission to the horizontalizing operation by the horizontal control valve;

a second information obtaining portion to obtain at least either one of upward operation of the boom and upward movement of the boom; and

a horizontal controller to set the switching valve from the activating position to the stopping position when the first information obtaining portion obtains the non-permission and the second information obtaining portion obtains either one of the upward operation of the boom and the upward movement of the boom, wherein

the horizontal controller holds the switching valve at the activating position when the first information obtaining portion has obtained the non-permission and the second information obtaining portion has not obtained at least either one of the upward operation of the boom and the upward movement of the boom.

2. The hydraulic system according to claim 1 , comprising

a start switch to allow at least the controller device to be activated,

wherein the horizontal controller holds the switching valve at the activating position when the start switch allows the controller device to be activated.

3. A control method of a hydraulic system for a working machine including: a boom cylinder to move a boom upward and downward; a working tool cylinder to move a working tool attached to the boom; a boom control valve to control the boom cylinder; a working tool control valve to control the working tool cylinder; a horizontal control valve including a switching valve having an activating position to allow a horizontalizing operation of the working tool and a stopping position to stop the horizontalizing operation; and a controller device to control the horizontal control valve, comprising:

obtaining permission and non-permission to a horizontalizing operation by the horizontal control valve;

setting the switching valve from the activating position to the stopping position upon obtaining either one of an upward operation of the boom and an upward movement of the boom under the non-permission to the horizontalizing operation; and

holding the switching valve at the activating position upon having not obtained at least either one of the upward operation and the upward movement under the non-permission to the horizontalizing operation.

4. The hydraulic system according to claim 1 ,

wherein the horizontal controller sets the switching valve from the stopping position to the activating position when the second information obtaining portion finishes obtaining either one of the upward operation and the upward movement, after the second information obtaining portion obtains either one of the upward operation and the upward movement and the switching valve is set from the activating position to the stopping position.

5. The hydraulic system according to claim 1 ,

wherein the horizontal controller sets the switching valve to the activating position under the permission to the horizontalizing operation regardless of the upward operation and the upward movement.

6. The hydraulic system according to claim 1 ,

wherein the horizontal controller sets the switching valve from the activating position to the stopping position when the first information obtaining portion obtains the non-permission and the second information obtaining portion obtains either one of the upward operation and the upward movement under the permission to the horizontalizing operation.

7. The hydraulic system according to claim 1 ,

wherein the horizontal controller continuously holds the switching valve at the activating position when the first information obtaining portion has not obtained the non-permission under the permission to the horizontalizing operation and/or when the second information obtaining portion has not obtained either one of the upward operation and the upward movement under the permission to the horizontalizing operation.

8. The hydraulic system according to claim 1 , comprising

a ride controller device to perform a damping operation to suppress pressure fluctuation of the boom cylinder,

wherein the controller device has

a third information obtaining portion to obtain permission and non-permission to the damping operation of the ride controller device,

and wherein the horizontal controller holds the switching valve at the stopping position when the third information obtaining portion obtains the permission of the damping operation, and holds the switching valve at the activating position when the third information obtaining portion obtains the non-permission of the damping operation.

9. The control method according to claim 3 , comprising

setting the switching valve from the stopping position to the activating position upon finishing obtaining either one of the upward operation and the upward movement, after obtaining either one of the upward operation and the upward movement and setting the switching valve from the activating position to the stopping position.

10. The hydraulic system according to claim 2 ,

wherein the horizontal controller sets the switching valve from the stopping position to the activating position when the second information obtaining portion finishes obtaining either one of the upward operation and the upward movement, after the second information obtaining portion obtains either one of the upward operation and the upward movement and the switching valve is set from the activating position to the stopping position.

11. The hydraulic system according to claim 4 ,

wherein the horizontal controller sets the switching valve from the activating position to the stopping position when the first information obtaining portion obtains the non-permission and the second information obtaining portion obtains either one of the upward operation and the upward movement under the permission to the horizontalizing operation.

12. The hydraulic system according to claim 2 ,

wherein the horizontal controller sets the switching valve to the activating position under the permission to the horizontalizing operation regardless of the upward operation and the upward movement.

13. The hydraulic system according to claim 2 ,

wherein the horizontal controller sets the switching valve from the activating position to the stopping position when the first information obtaining portion obtains the non-permission and the second information obtaining portion obtains either one of the upward operation and the upward movement under the permission to the horizontalizing operation.

14. The hydraulic system according to claim 4 ,

wherein the horizontal controller sets the switching valve to the activating position under the permission to the horizontalizing operation regardless of the upward operation and the upward movement.