GB879343A - Compressor unloader devices - Google Patents

Abstract

879,343. Regulating compressors. JOY MANUFACTURING CO. Sept. 21, 1959, No. 32029/59. Class 8(1). A compressor unloader 7, Fig. 1, is actuated by a high pressure hydraulic medium working in a control line 36 connected to the control means, comprising a casing 2, connected to the compressor housing 17, containing a reservoir 22 formed between casing 2 and barrel 26 in which moves a plunger 4, the said plunger being receiver pressure rotated and having helical control edges 74, Fig. 2, co-operable with ports 65 and an annular space 72 behind the head of said plunger whereby when the pressure in the barrel chamber is decreasing, plunger valve 54 opens releasing high pressure fluid from line 36, Y piece 56, channels 52, 60, 64, Fig. 7, (not shown), ports 65, relief space 72, holes 68 into the reservoir 22, said reservoir having a large volume relative to line 36. as the receiver pressure rises, the helical control edges are rotated causing the ports 65 to open later and later thereby maintaining the pressure in line 36 for a greater portion of the compressor's compression stroke. As the suction stroke of the compressor commences the plunger 4 is moved along the barrel 26, towards the cylindrical valve block, expelling fluid through the ports 66 until when the head of said plunger passes ports 66 the remaining fluid is compressed until at a predetermined pressure, check valve 44 opens, releasing the high pressure fluid to line 36 and the unloader 7 ; the stroke of the plunger reverses as the compressor piston reverses to commence its compression stroke.