| 摘要 |
A hydraulic fuse or cut-off device divides fluid flow into: (i) a primary fluid stream; and (ii) a secondary fluid stream having a substantially constant, but small ratio of flow to said primary stream. The secondary stream exerts pressure on a timing piston (7) which thereby monitors the entire flow and causes the fuse to cut-off when a predetermined volume of fluid has passed through the device. The fuse includes a regulating piston (6) for building inlet pressure to a value sufficient to develop the power necessary to drive the timing piston. Greater simplicity of the component parts and decreased sensitivity to contamination results from the use of a small fluid orifice to control the secondary stream. This is achieved by fitting the regulating piston with an inwardly directed flange (9), just touching the peripheral surface of a slightly tapered, central pin (10) whereby the taper of the pin causes the orifice to be created as the regulating piston is caused to slide as a result of the primary fluid flow. |
