Hydraulic circuit, and combination valve used in same hydraulic circuit

A hydraulic circuit comprising:

• a hydraulic power supplier including a tank configured to store hydraulic oil, and a hydraulic pump coupled to the tank and configured to feed hydraulic pressure oil;
• a stack valve coupled to the hydraulic power supplier, the stack valve including a direction switching valve configured to control supply/discharge of the hydraulic pressure oil from the hydraulic power supplier to a hydraulic device;
• a multifunction valve provided in the vicinity of the hydraulic device, the multifunction valve including (i) a first stop valve and a second stop valve which respectively open/close a first supply/discharge circuit and a second supply/discharge circuit for the hydraulic device, and (ii) a bypass circuit positioned closer to the stack valve than the first stop valve and the second stop valve, the bypass circuit including a third stop valve;
• and
• a composite valve coupled to the hydraulic power supplier, the stack valve, and the multifunction valve, wherein the composite valve includes:
• a multifunction valve-side first passage including a multifunction valve-side first stop valve configured to open/close communication between the multifunction valve and the stack valve;
• a multifunction valve-side second passage including a multifunction valve-side second stop valve configured to open/close communication between the multifunction valve and the stack valve;
• a pump-side passage including a pump-side stop valve configured to open/close communication between the hydraulic pump and the stack valve;
• a tank-side passage including a tank-side stop valve configured to open/close communication between the tank and the stack valve;
• a pump-side bypass circuit branching off from the pump-side passage at a position closer to the pump than the pump-side stop valve, the pump-side bypass circuit including a pump-side bypass stop valve configured to open/close communication with the multifunction valve-side second passage;
• and
• a tank-side bypass circuit branching off from the tank-side passage at a position closer to the tank than the tank-side stop valve, the tank-side bypass circuit including a tank-side stop valve configured to open/close communication with the multifunction valve-side first passage.

A hydraulic circuit comprising:

• a hydraulic power supplier including a tank configured to store hydraulic oil, and a hydraulic pump coupled to the tank and configured to feed hydraulic pressure oil;
• a stack valve coupled to the hydraulic power supplier, the stack valve including a direction switching valve configured to control supply/discharge of the hydraulic pressure oil from the hydraulic power supplier to a hydraulic device;
• a multifunction valve provided in the vicinity of the hydraulic device, the multifunction valve including (i) a first stop valve and a second stop valve which respectively open/close a first supply/discharge circuit and a second supply/discharge circuit for the hydraulic device, and (ii) a bypass circuit positioned closer to the stack valve than the first stop valve and the second stop valve, the bypass circuit including a third stop valve;
• and
• a composite valve coupled to the hydraulic power supplier, the stack valve, and the multifunction valve, wherein the composite valve includes:
• a multifunction valve-side first passage including a multifunction valve-side first stop valve configured to open/close communication between the multifunction valve and the stack valve;
• a multifunction valve-side second passage including a multifunction valve-side second stop valve configured to open/close communication between the multifunction valve and the stack valve;
• a pump-side passage including a pump-side stop valve configured to open/close communication between the hydraulic pump and the stack valve;
• a tank-side passage including a tank-side stop valve configured to open/close communication between the tank and the stack valve;
• and
• a direction switching valve configured to change a manner of communication of the pump-side passage and the tank-side passage with the multifunction valve-side first passage and the multifunction valve-side second passage.

A composite valve having a composite valve unit, the composite valve unit comprising:

• a P-port coupled to a hydraulic pump, a T-port coupled to a tank circuit, an A-port coupled to a first supply/discharge circuit, and a B-port coupled to a second supply/discharge circuit;
• and
• a P1-port connected with the P-port, a T1-port connected with the T-port, an A1-port connected with the A-port, and a B1-port connected with the B-port, wherein the composite valve unit 30a further comprises:
• a first section including
• (i) a first left passage structure connecting the P-port with the P1-port, the first left passage structure including a first left U-shape passage including a lower passage provided with a pump-side stop valve, and
• (ii) a first right passage structure connecting the T-port with the T1-port, the first right passage structure including (a) a first right U-shape passage including a lower passage which is positioned substantially coaxially with an upper passage of the first left U-shape passage and is provided with a tank-side stop valve, and (b) a first T-shape passage which is positioned substantially coaxially with the lower passage of the first left U-shape passage and is provided with a tank-side bypass stop valve;
• and
• a second section including
• (i) a second right passage structure connecting the A-port with the A1-port, the second right passage structure including a second right U-shape passage including a lower passage provided with a multifunction valve-side second stop valve, and
• (ii) a second left passage structure connecting the B-port with the B1-port, the second left passage structure including (a) a second left U-shape passage including a lower passage which is positioned substantially coaxially with an upper passage of the second right U-shape passage and is provided with a multifunction valve-side first stop valve, and (b) a second T-shape passage which is positioned coaxially with the lower passage of the second right U-shape passage and is provided with a pump-side bypass stop valve, and wherein the first left passage structure is substantially same as the second right passage structure while the first right passage structure is substantially same as the second left passage structure when either one of the first section and the second section is rotated 180 degrees in a horizontal direction, and a pump-side bypass circuit couples the lower passage of the first left passage structure of the first section with the second T-shape passage of the second section via the pump-side bypass stop valve, while a tank-side bypass circuit couples the lower passage of the second right passage structure of the second section with the first T-shape passage of the first section via the tank-side bypass stop valve.