| 摘要 |
<p>A pressure regulator comprises a housing (12), a metering spool (13) movable within the housing (12) to control the degree of opening of a metering orifice (23, 24) of the regulator, a first inlet (23) through which hydraulic fluid at high pressure is supplied to said metering orifice (23, 24), a first pressure chamber (22) within the housing (12) and containing hydraulic fluid at a reference pressure (P ref ) to which one end of said metering spool (13) is exposed, compression spring means (15) within said first pressure chamber (22) and acting at one end against said one end of said metering spool (13), an outlet (27) from the housing (12) downstream of said metering orifice (23, 24), for hydraulic fluid at regulated pressure (P reg ) from said metering orifice (23, 24), a second pressure chamber (28) containing hydraulic fluid at said regulated pressure P reg to which the opposite end of said metering spool (13) is exposed, such that the metering position of the metering spool (13) relative to the housing (12) is a position of equilibrium between the force of the spring (15) and P ref acting on one end of said metering spool (13) and P reg acting on the other end of the metering spool (13), said equilibrium position changing to maintain a predetermined pressure difference (P diff ) between P ref and P reg , and the regulator further including an abutment (14) against which the opposite end of said compression spring means (15) reacts and a third pressure chamber (19) containing hydraulic fluid at a control pressure (P con ) acting on said abutment (14), whereby the value of P con can be changed to adjust the position of said abutment (14) relative to the housing (12) of the regulator to change the pre-load of said compression spring means (15) thereby to adjust the value of P diff .</p> |
