| 摘要 |
<p>PCT No. PCT/EP86/00352 Sec. 371 Date Feb. 12, 1987 Sec. 102(e) Date Feb. 12, 1987 PCT Filed Jun. 13, 1986 PCT Pub. No. WO86/07475 PCT Pub. Date Dec. 18, 1986.A control valve for regulating and maintaining the pressure ratio between two pressures (p1 and p2) associated, respectively, with two separate pressure systems at a constant value. In particular, the pressure (p2), prevailing in hydraulic cylinders which serve to press one press roll against a counter roll in a roll press, is controlled as a function of the pressure (p1) of the fluid which transfers the contact pressure in a deflection adjusting roll of the roll press. The control valve includes a piston, movably disposed in the housing of the control valve, and provided with a first end face area (A1) at one end thereof and a second end face area (A2) at the opposite end thereof. The end face area (A1) is subjected to the first pressure (p1) in a first pressure chamber (1a) and the second end face area (A2) is subjected to the second pressure (p2) in a second pressure chamber (2a). The piston and the housing form between themselves a first overflow gap (S2) which connects the second pressure chamber (2a) to a low-pressure chamber (4a), enabling fluid to flow controllably from the second pressure chamber at a rate which maintains the desired pressure ratio. The piston and the housing define an additional overflow gap (S1) which connects the first pressure chamber (1a) to another low-pressure chamber (3a). Whenever the second pressure (p2) falls below a given pressure value, the additional overflow gap (S1) opens and the first pressure (p1) drops so as to maintain the desired pressure ratio.</p> |
