Patent ID: 9377013
Filing Date: 2016-06-28
CPC Classification: F04B,F04C

Claim Text:
1. An oil injection device for a variable-speed scroll refrigeration compressor, the oil injection device comprising: an oil displacement pump designed to be rotationally coupled to a rotor of an electric motor of the compressor, the oil displacement pump comprising an oil inlet port designed to be connected to an oil sump of the compressor and a first oil outlet port; at least one oil injection duct connected to the first oil outlet port of the oil displacement pump and designed to supply a compression stage of the compressor with oil; an oil return duct connected to the first oil outlet port of the oil displacement pump and designed to return oil into the oil sump of the compressor; and a connector configured to be positioned inside a sealed enclosure of the compressor, the connector having (1) at least oil inlet port supplied with oil through a supply duct connected to the first outlet port of the oil displacement pump, (2) a first oil outlet port connected to the oil injection duct, and (3) a second oil outlet port connected to the oil return duct, wherein the oil injection duct and the oil return duct are configured such that (i) pressure losses in the oil injection duct are primarily singular pressure losses proportional to a square of an oil flow rate passing through the oil injection duct, and such that pressure losses in the oil return duct are primarily pressure losses due to friction proportional to an oil flow rate passing through the oil return duct, (ii) the pressure losses in the oil injection duct are lower than the pressure losses in the oil return duct when a speed of rotation of the oil displacement pump is lower than a first predetermined value, and (iii) the pressure losses in the oil injection duct are greater than the pressure losses in the oil return duct when the speed of rotation of the oil displacement pump is above a second predetermined value, the second predetermined value being greater than or equal to the first predetermined value, and wherein the oil injection device is configured to monitor injection of oil in the compression stage without a solenoid valve.