Hydraulic cylinder spool valve device

A hydraulic cylinder spool valve device, which extends and retracts a cylinder rod of a hydraulic cylinder by controlling a flow direction and a flow rate of a working fluid by moving spools in accordance with operation command values, the hydraulic cylinder spool valve device comprising:

• a first spool valve having a characteristic which includes a first dead band and a first opening characteristic in which an opening area of the working fluid, supplied in a direction in which the cylinder rod is extended, increases in accordance with a movement of a first spool;
• a second spool valve having a characteristic which includes a second dead band and a second opening characteristic in which the opening area of the working fluid, supplied in a direction in which the cylinder rod is retracted, increases in accordance with a movement of a second spool;
• and
• a controller configured to, when the working fluid is supplied in accordance with the first opening characteristic, perform communication with the hydraulic cylinder by using the first spool valve and position the second spool of the second spool valve within the second dead band, configured to, when the working fluid is supplied in accordance with the second opening characteristic, perform communication with the hydraulic cylinder by using the second spool valve and position the first spool of the first spool valve within the first dead band, and configured to, during switching between the first opening characteristic and the second opening characteristic, adjust a characteristic of a switching dead band between the first opening characteristic and the second opening characteristic,
• wherein
• the characteristic of the first spool valve further includes a third opening characteristic in which the opening area of the working fluid, supplied in the direction in which the cylinder rod is retracted, increases in accordance with the movement of the first spool from the first dead band,
• the characteristic of the second spool valve further includes a fourth opening characteristic in which the opening area of the working fluid, supplied in the direction in which the cylinder rod is extended, increases in accordance with the movement of the second spool from the second dead band, and
• the controller configured to, when the working fluid is supplied in accordance with the third opening characteristic, further perform communication with the hydraulic cylinder by using the first spool valve and position the second spool of the second spool valve within the second dead band, configured to, when the working fluid is supplied in accordance with the fourth opening characteristic, perform communication with the hydraulic cylinder by using the second spool valve and position the first spool of the first spool valve within the first dead band, and configured to, during switching between the third opening characteristic and the fourth opening characteristic, adjust a switching dead band between the third opening characteristic and the fourth opening characteristic.