| 摘要 |
<p>This hydraulic brake prevents overspeeding of pump or drive rotor of a central heating pump (2) if a pipe should burst. The braking is applied progressively and automatically. An extension (9) of the drive motor (3) shaft passes through a seal (26) into a chamber (8) and carries a number of vanes (23). These vanes rotate with small clearance within a ring of stator vanes (18) in the chamber. Braking fluid (11) under pressure from an air bottle (15) passes via a valve (24) to the chamber if the control valve (16) to the bottle is activated by a device (17) signalling a burst pipe by loss of pressure. As the chamber fills, the viscous friction between the vanes causes a progressive increase of braking torque on the motor shaft. To reduce power loss when the system is working normally, the chamber may be evacuated or filled with a light gas such as hydrogen, making use of an overflow and vent pipe (27). In either case, it is arranged that the burst pipe signal also operates the discharge valve (24).</p> |
