| 摘要 |
<p>Electrohydraulic proportional valve comprising an electromagnetic force motor (10), a pilot actuator assembly (12), and a main spool and body assembly (14). The pilot actuator assembly (12) comprises a pilot spool (22) slidably received in a pilot sleeve (24) and a feedback spool (26) which has a camming surface (28) against which the pilot sleeve (24) rides. The camming surface (28) comprises a first portion (36) in which the position of the pilot sleeve (24) is a function of the axial position of the camming surface (28) and a second portion (38) immediately adjacent the first portion (36) in which the position of the pilot sleeve (24) is constant regardless of the axial position of the camming surface (28). The main spool and body assembly (14) comprises a main spool (88) connected to the pilot actuator assembly (12), first and second load holding check valves (120 and 122) slidably disposed in a bore (118), first means for communicating pilot supply pressure to a reduced diameter area (124) on the main spool (88) when it is in the float position, and second means for communicating pilot supply pressure from the reduced diameter area (124) on the main spool (88) to the bore (118) between the first and second load holding check valves (120 and 122) when the main spool (88) is in its float position. </p> |
