GB1288820A - - Google Patents

Abstract

1288820 Electric correspondence control GRUNDIG E M V ELEKTRO-MECHANISCHE VERSUCHSANSTALT INH MAX GRUNDIG 23 Dec 1970 [23 Dec 1969] 61234/70 Heading G1N [Also in Division F1] Apparatus for controlling the positions of the lower and upper working pistons 1, 2 enclosing combustion space 3 in an opposed piston engine having hydrostatic movement converters with hydraulic pistons 6, 7, rotary converter 10, driving shaft 11 and fluid control valves 12, 16 acting on fluid columns 8, 9 comprises transducers 18, 19 providing from respective synchronous rectifiers 20o, 20u, correspondence error signals, related to the difference between piston position and driving shaft angular position for each working piston, which are fed to change-over switch 25 which, at a predetermined engine speed, changes to receive piston dead-point error signals from a differential transformer, 28-34, thereby to control the fluidpressure in columns 8, 9 in accordance with deadpoint error, that for the upper piston being corrected in accordance with that for the lower piston. Transducers 18, 19 are A.C. resolvers and engine speed is measured by comparing the time between two dead-point signals from transducer 21 with a calibrated timing circuit or with the signal from a reference oscillator 24 so that when a predetermined speed is reached switch 25 is actuated. The signal from the lower piston deadpoint transducer 21u is fed to a mixer 27 where it is inverted and added to the signal from the upper piston dead-point transducer. Further details of the control circuits are given in Figs. 5-7 (not shown) and it is stated that by superimposing an appropriate direct voltage upon the output voltage from the differential transformer the compression ratio in the cylinder may be varied at will.