GB961380A - Dynamometer system - Google Patents

Abstract

961,380. Dynamometers. DE HAVILLAND ENGINE CO. Ltd. May 3, 1963 [July 30, 1962, No. 29269/62. Heading G1W. A dynamometer for measuring the horse power of a motive power source comprises a centrifugal pump for circulating liquid in a circuit containing a variable throttle, means for supplying cooling liquid at a controlled rate to mix with the circulating liquid and a thermometer to measure the temperature rise of the cooling liquid. This temperature increase is related to the horse power developed by an engine driving the pump. The engine to be tested is coupled to a shaft 11, (Fig. 1) carrying a four bladed impeller 12 which circulates water in a path 13 radially outwardly then through an annular passage 14 containing an adjustable throttle 15 (detailed in Fig. 2) and into a mixing chamber 16. The load imposed on the engine is dependent on the size of the throttle orifice. The energy developed by the impeller appears as a rise in temperature of the circulating water. This heat is removed by passing cooling water from a pipe 17 through the mixing chamber-16 and out through discharge 18 controlled by a valve 19. Once a steady temperature is attained the temperature rise between pipes 17 and 18, as communicated by thermometer bulbs 23, 24 to a differential thermometer 22, will give a measure of the horse power of the engine, the thermometer being calibrated in horse power units. The throttle valve may comprise a fixed slotted plate 25 (Fig. 2) and a movable slotted plate 26 which can be turned through an angle 27 so that corresponding slots on the plates overlap to a greater or lesser extent. A lever 32 on the plate 26 can be calibrated in terms of the load applied to the engine. In an alternative type of throttle valve (Fig. 3 not shown) there is an annular cylindrical ring surrounding and spaced from the circumferential periphery of the impeller and movable axially to vary the radial discharge from the impeller.