Patent GB-941831-A (GB)
Title: Improvements in pressure-fluid motors
Inventor: BARR JOHN CHARLES
IPC: F01B25/00
Filed: 1958-12-04
Abstract: 941,831. Turbines. TURBOMACHINES Ltd. Dec. 3, 1959 [Dec. 4, 1958; May 12, 1959], Nos. 39198/58 and 16236/59. Heading FIT. A turbine comprises a casing and a hollow rotor disposed therein, fluid under pressure being supplied to the space within the rotor and discharging thereform through nozzles formed in the rotor, the nozzles being so shaped that the rotor is caused to rotate by the reaction of the issuing fluid jets. The supply of pressure fluid to the rotor nozzles is controlled by a device which is urged towards its cut-off position in response to the speed of rotation of the rotor, the control device being loaded in the opening direction by pressure derived from the working fluid. The turbine may be operated by a gas, for example air, or by a liquid, for example oil, and is particularly suitable for portable use for example for driving portable tools. The turbine shown in Figs. 1 and 2 comprises a hollow rotor formed by a cup-shaped member 1 and a cover plate 2, fluid discharge nozzles 3 being formed in the side wall of the cup member 1. The rotor is mounted on a shaft 4 having a blind bore 7 to which fluid under pressure is supplied, the fluid passing into the hollow rotor through radial bores 10 in the shaft. The rotor shaft is rotatably supported within a casing 6 by means of bearings 5, one on either side of the rotor. A driving shaft 12 is also rotatably mounted in the casing in a bearing 11 and is connected to the rotor shaft by a universal joint 13. The supply of fluid into the rotor is controlled by means of a sleeve valve 26 co-operating with the bores 10, the sleeve 26 being moved towards the closing position by means of the centrifugal governor device 14, the centrifugal force being opposed by the pressure of the working fluid acting on the face 28. The sleeve 26 is provided with an annular recess 27 to which fluid flows from the openings 10, the pressure of the fluid then acting on the face 28 of the sleeve so as to oppose closing movement of the sleeve. The face 28 is shaped so that as the rim 32 approaches the face of the rotor, the fluid supply acting on the face 28 is restricted so that the centrifugal load on the sleeve can effect a positive closing action. The side wall of the rotor is also formed with hollow plug members 17 which have a weakened section at 18 so that in the event of excessive speed, the end portion of the plug becomes detached and fluid by-passes the reaction nozzles 3. The bores in which the plugs are mounted may be directed so that a retarding torque is produced. In Fig 3, a ball is disposed within a radial passage 20 in the rotor and acts as a valve to control flow of fluid from the openings 10 through the passage 21 to the nozzles 3. Centrifugal force tends to move the ball outwardly against the pressure of the fluid, the ball cutting off the supply of fluid at a predetermined speed of rotation. The passage 20 is vented to atmosphere through duct 25. Plug members 23 are utilized in the rotor shown in Fig. 4 in place of the ball 19 shown in Fig. 3, the plugs 23 controlling flow of fluid through passages 21 which lead to transverse passages 24 and thence to chambers which commiuncate with the reaction nozzles 3. The radial movement of the plugs 23 is limited so that the opening 21 is never completely closed, whereby pressure fluid always acts on the plug so as to oppose radially outward movement thereof due to centrifugal force.