Seal device for hydraulic circuit

A device for a hydraulic circuit comprising:

• a supply passage configured to supply hydraulic oil to a hydraulic actuator operated by hydraulic pressure, and formed over at least two members that relatively move;
• a discharge passage configured to discharge the hydraulic oil from the hydraulic actuator, and formed over the at least two members;
• a seal member that seals a gap between the at least two members in a liquid-tight manner is disposed in an interior of a groove section that is formed in at least one of the at least two members;
• a supply communication section that allows the groove section to communicate with the supply passage at a position midstream of the supply passage;
• and
• a discharge communication section that allows the groove section to communicate with the discharge passage at a position midstream of the discharge passage,
• wherein the seal member continuously seals the gap,
• wherein the at least two members includes a shaft member and a rotating member that is fitted on an outer peripheral side of the shaft member and has the hydraulic actuator,
• the supply passage is formed to pass through an interior of the shaft member, to include an opening that opens on an outer peripheral surface of the shaft member, and further to pass through a section of the rotating member so as to allow communication between the opening of the supply passage and the hydraulic actuator,
• the discharge passage is formed to pass through the interior of the shaft member, to include an opening that opens in a position offset from the opening of the supply passage in a circumferential direction, and to pass through a section of the rotating member so as to allow communication between the opening of the discharge passage and the hydraulic actuator, and
• the seal member is disposed between the shaft member and the rotating member.

A device for a hydraulic circuit comprising:

• a supply passage configured to supply hydraulic oil to a hydraulic actuator operated by hydraulic pressure, and formed over at least two members that relatively move;
• a discharge passage configured to discharge the hydraulic oil from the hydraulic actuator, and formed over the at least two members;
• a seal member that seals a gap between the at least two members in a liquid-tight manner is disposed in an interior of a groove section that is formed in at least one of the at least two members;
• a supply communication section that allows the groove section to communicate with the supply passage at a position midstream of the supply passage;
• a discharge communication section that allows the groove section to communicate with the discharge passage at a position midstream of the discharge passage;
• a pressure increase valve that selectively allows communication between the supply passage and a hydraulic pressure source;
• and
• a pressure reduction valve that selectively allows communication between the discharge passage and a prescribed chain portion,
• wherein the seal member continuously seals the gap, and
• wherein the device is configured such that when an estimation that a temperature of the hydraulic oil contacting the seal member increases to a prescribed value or higher is made, at least either one of the pressure increase valve and the pressure reduction valve is opened, and flow of the hydraulic oil is caused in the supply passage, discharge passage, and the groove section that communicates via the supply communication section and the discharge communication section.