GB496351A - Improvements in and relating to rotary compressors - Google Patents

Abstract

496,351. Rotary compressors. DEMAG AKT.-GES. Feb. 16, 1938, No. 4848. Convention date, Feb. 16, 1937. [Class 110 (ii)] A rotary compressor is shifted over to no-load running condition in the event of failure of the supply of driving medium to the motor driving the compressor. An electromagnet 4 is energized when current is being supplied to the electric driving motor, and holds closed a valve 6, and a valve 7 open, against the weight 8, or a spring. When the current fails, the valve 6 opens, valve 7 closes, and fluid under pressure flows from a tank 9 to force down a piston 10 and close a valve 1, thus closing the suction pipe to the compressor. The compressor runs idle driving gas out past a valve 2, to the atmosphere. The compressor is loaded only when its operating speed is reached, by means of an auxiliary relay 11 which controls the magnet 4 in combination with a retarding device. When the motor is stopped, the retarding device acts by first causing the relay 11 to fall and thus break the circuit of the magnet to set the compressor to idle running. After a time lapse the main switch falls out. Fig. 2 shows a plant with low and high pressure compressors N, H, respectively, and an intercooler Z and a condensate receiver K. The compressed gas in the parts Z, K, drives the compressor H forward when the. regulator R has closed the shut-off valve in the suction pipe of the compressor N. A pressure switch 16 under the influence of pressure fluid in the tank 9, breaks the circuit to the magnet 4 when a pre-determined allowable pressure is reached. In the device shown in Fig. 3, the pressure in the tank 9 acts through a pipe 19 to raise a valve 18 and connect pipes 19 and 27, and close the outlets to atmosphere 28. Balls 21 are thrust aside when the valve 18 is lifted against the load of a ball 20. In its lowest position the valve 18 connects a pipe 27, leading to the space above the valve 10, to the air outlets 28.