GB784676A - Improvements relating to dynamometers - Google Patents

Abstract

784,676. Air-brake dynamometers. SOC. PER AZIONI ASPERA. May 4, 1956, No. 13846/56. Class 106 (2). A dynamometer for measuring engine power output comprises a multi-stage axial flow air compressor operating in a closed cycle. The input shaft 6, Fig. 2, is connected through interchangeable gears in a housing 40b with a shaft 11 coupled to and driving a drum 49. The drum 49 carries a plurality of blades subdivided into four sets 13a, 13b, 13c, 13d, each blade being mounted on a spindle rotatable in the drum 49. The blades of sets 13a, 13b give an axial air flow opposite to the air flow set up by the blades of sets 13c, 13d. If the shaft 6 is rotated in a direction causing the air flows set up to collect in a central annular chamber 50, this air thus flows in the direction denoted by arrow a to a foundation 41, then outwardly in opposite directions, and finally upwards as denoted by arrows b back to the suction side of the blades. The angular setting of the blades 13a, 13b, 13c, 13d can be varied simultaneously by means of a handle (not shown in Fig. 1) that can be turned to cause a common axial displacement of a number of radial arms 15a, 15b, 15c and 15d rotating with the drum 49. These arms are coupled through pin-and-socket means with spindles 12a, 12b, 12c, 12d extending from the blades 13a, 13b, 13c, 13d and axial movement of said arms turns the spindles 12a, 12b carrying the blades 13a, 13b in one direction and the spindles 12c, 12d carrying the blades 13c and 13d in the opposite direction. The braking torque set up can thus be varied. Flow deflectors 27b, Fig. 6, are interposed between each pair of blade sets such as 13c, 13d and comprise flat discs in which slots are provided to deflect the flow from a set of blades, for instance the blades 13d, to oppose the rotation of the other set of blades, such as 13c. Measuring the torque. A rocking frame or cradle associated with the gears in the housing 40b has an arm 9, Fig. 7, acting on a piston 31 in a cylinder 32 filled with liquid at one end 35. When the cradle tends to rock, the resulting torque causes the liquid in the cylinder to be compressed and actuate a pressure gauge. Between the piston 31 and the cylinder 32 are a number of coaxial sleeves 65, 66 and one or more of these sleeves can, by means of a handle 33a and arm 67, be caused to rise with the piston 31 to vary the measuring range. Torque measurements can be made on engines rotating in either direction. For rotation in one direction the arm 9 tends to rise and causes the piston 31 and any sleeve coupled therewith to rise, the reaction being taken up by the plate 61. For rotation in the other direction, the spherical portion 9c of the arm 9 abuts the bottom 32c of the cylinder 32 which is thereby lowered by virtue of a slip coupling between the cylindrical boss 63a and a hole in the plate 61. Reaction is then taken up by a bracket 2 fast with the brake shell, abutted by the piston 31 through the arm 33 for the handle 33a.