Screw compressor comprising two helical rotors intermeshing one in the other and an axially movable control spool for the adjustment of the discharge rate and for the oil injection.

摘要

1,237,333. Screw compressors. GUTEHOFFNUNGSHUTTE STERKRADE A. G. Oct.15, 1969 [Oct. 24, 1968], No.50619/69. Heading F1F. To regulate the output of a screw compressor having main and auxiliary intermeshing screwed rotors 2, 3, Figs. 1, 4 driven by a worm 4 and worm wheel 5, an axially adjustable control slide 7 has a plurality of transverse bores 17 communicating with the compressor working chamber through bores 18 and with an elongate feed opening 19SP1/SP from a passage 19 supplied with lubricating oil under pressure. As the control slide 7 is adjusted rightwardly on rotation of a screwed shaft 9 either by a motor (not shown) or by means of a handwheel 10, the rightmost bore 17SP1/SP is moved out of communication with the opening 19SP1/SP whilst another bore 17SP11/SP is brought into communication with the opening 19SP1/SP so that the zone of the rotors receiving the oil is only insignificantly displaced with decrease in compressor output. As shown, the opening 19SP1/SP co-operates with five bores at any one time, the number may however be different and there may be more than one opening 19SP1/SP with associated bores. In an alternative embodiment, lubricant may be admitted to an annular chamber 21, Fig. 5, in a stationary piston 20 which is supplied through bores 22, 23 by a lubricating pump (not shown). On adjustment of a control slide 7SP1/SP, bores 18 are brought into and out of register with the chamber 21 in a similar manner to the bores 17 with respect to the opening 19SP1/SP.