GB1164863A - Refrigeration control apparatus. - Google Patents

Abstract

1,164,863. Refrigerating. REFRIGERATING SPECIALTIES CO. 25 Nov., 1966, No. 53006/66. Heading F4H. [Also in Division G3] The flow of refrigerant in a compressor controlled refrigerator is controlled by a normally closed valve 20, Fig. 1, connected in a first pressure line 51 and linked to a pressure responsive element 35 which is movable by a control pressure to open the control valve, a main pressure regulator 38 consisting of a regulating valve 45 connecting a second pressure line 37 to a control pressure line 55 leading to the element 35, and a pressure responsive member to which the valve 45 is linked, the member 42 being subjected to pressure from the line 55 to effect closing of the valve 45 and to combined pressure from the first pressure line and a spring 47 to effect opening of the valve 45 to an extent at which a pressure differential between the control pressure and a pressure including the pressure from the first pressure line 51 acting normally to close the valve 20 is maintained at a predetermined amount. The valve 20 regulates the flow from an evaporator 19 to a compressor 10 and has its pressure responsive element 35 connected to the outlet of the main regulator 38 through a pilot regulator 56 set at, say, 5 p.s.i. above evaporator pressure. The differential between lines 51 and 55 necessary to open the valve 38 is also set at 5 p.s.i. so that if the evaporator pressure increases the pilot regulator and valve 20 open until the evaporator pressure is lowered to the desired level. During start-up when the evaporator pressure is higher than that in the compressor, check valves 67 and 66 are open and closed, respectively, to permit the main regulator 38 to open. A solenoid shut-off valve 68 can be provided in the connection from the compressor output to the main pressure regulator 38 or a similar valve responsive to pressure or temperature may be used in place of the pilot regulator 56. To avoid overloading the compressor during a warm evaporation or hot gas defrost period an orifice having a flow capacity of about three times that of an orifice 65 in the pressure responsive member 35 is provided in the line 55. The invention may also be applied to a two-stage system with two compressors and an intercooler. Two evaporators may also be employed and the pilot regulators may be replaced by solenoid or thermally responsive valves. Fig. 5 illustrates a modification in which a flow control valve 80 may be located in any portion of the system at condensing pressure and an air or evaporative cooled condenser 82 has a separate receiver 13a for high pressure liquid storage. To avoid excess leakage and damage which might result from using the full difference between condensing pressure and suction pressure to operate the valve 80 the pressure at the inlet 84 of the main regulator is maintained at about 2 to 10 p.s.i. below the pressure at the exit 94 of the valve 80. A spring 89 adjusted by screw 92 hermetically sealed by a cap 93 varies the amount by which pressure at inlet 84 must be less than the pressure in a conduit 102 communicating with the inlet of the flow control valve to open valve 91. The valve 80 may be positioned at 80a, 80b or 80c or combinations of these positions may be used.