| 摘要 |
<p>1,050,181. Fluid-pressure servomotor systems. HYDRAULIC UNIT SPECIALTIES CO. March 16, 1965 [March 23, 1964], No.11128/65. Heading G3P. The connection of motor ports 24, 25 to either a supply pump 6 or a reservoir 8 is determined by a control valve 11 whilst the flow conditions are regulated by two identical valves 21 each in series with one of the ports 24, 25; each valve 21 consists of main and pilot closures 39, 40 the latter being interconnected by a piston 32 the ends of which are subjected to the pressure in the paths leading to the motor ports. With the control valve 11 in the neutral position both main closures 39 are seated by springs 49 to hydraulically lock the motor connected to the ports 24, 25. When the control valve 11 is moved to an operating position e. g. to connect a passage 19 to the pump and a passage 20 to the reservoir, the pressure in the passage 19 unseats the main closure 39 to connect the passage to the port 24, the fluid within the main valve being expelled in-. to the port 24 via passages in the valve. The pilot closure 40 remains seated. If the ports 24, 25 are connected to the lowering and lifting sides of a boom lift motor the valve 21 in the reservoir path remains closed until sufficient pressure has built up in passage 19 to move the piston 32 to the right so unseating the associated pilot valve 40 which opens the reservoir path for the fluid within the main valve 39 so that the latter may be opened by the pressure at port 25 whereupon the boom descends. In the event of cavitation the pressure in passage 19 falls and the right-hand pilot closes or tends to close as does the main valve thereby closing off or throttling the fluid flowing to the reservoir. A similar but reverse operation occurs when the control valve 11 is moved to its other position. Each pilot valve may be hydraulically balanced or slightly unbalanced into the seated position. A pair of series connected relief valves 73 are disposed between the ports 24, 25.</p> |
