| 摘要 |
<p>1,207,027. Hydraulic relief valve. DANFOSS A.S. Oct. 2, 1968 [Oct.17, 1967], No.46805/68. Heading F1P. A double acting piston device (13) Fig.1 (not shown) has two parallel one way valves (18 and 19, 20 and 21) across each side and a fluid return pipe one operative to relieve excess pressure to this pipe, the other allowing fluid to flow into the cylinder if cavitation take place. An additional valve (22, 23, 24) vents the cylinder only if the combined pressure in each end exceeds a maximum set lower than the over pressure relief limit. A combination drive is symmetrically arranged, the pressure pipes from each side of the cylinder communicating at 15, 16 respectively and the return pipe to the reservoir joining at 17. On excess pressure piston 27 or 28 respectively retracts to a stop 29 and further pressure causes valve 32 or 33 to open against a strong spring 34 or 35. Low-pressure causes ball 42 or 43 to lift off its seating and admit fluid to the cylinder. If the combined pressure of the two parts of the cylinders exceeds the set maximum, both pistons 27, 28 will retract and eventually push rod 49 will engage balls 42, 43 and push them off their seating thus venting the system to the return pipe.</p> |
