A method and apparatus are disclosed for cooling a compressor that pressurizes a working fluid comprising a gas and optionally a liquid. A cooling fluid having a composition different from the working fluid is injected into the compression chamber of the compressor. The cooling fluid injection can occur during an intake stroke, while the working fluid is being drawn in to the compression chamber, or during a compression stroke, while the working fluid is pressurized in the first compression chamber. This produces a first pressurized mixture comprising the working fluid and the cooling fluid in the compression chamber. The pressurized mixture can be discharged from the compression chamber in response to the pressurized mixture satisfying a discharge condition. The delivery of the cooling fluid injected into the compression chamber can be automatically controlled for a successive intake stroke or a successive compression stroke in response to a control condition of the first pressurized mixture.

A compressor includes a cylinder block having a first bore and a cylinder head overlapping the cylinder block. The cylinder head has a second bore aligned with the first bore. The second bore is separated into a plurality of distinct regions including a suction region and an economizer region. A plurality of valves includes a suction valve selectively operable to fluidly couple the suction region and the first bore, and an economizer valve selectively operable to fluidly couple the economizer region and the first bore.

A method for controlling a first reference temperature in a device (1) for compressing gas, the device (1) including an oil-injected element (2) for compressing the gas; an oil injection pipe network (6) for injecting oil into the oil-injected element (2), including: an apportioning means (8) for apportioning the oil into a first part and into a second part; an oil cooler (10) cooled by a fan (9), for cooling the first part; and a bypass (11) for diverting the second part past the oil cooler (10). An apportioning proportion of the first part is controlled to a required apportioning proportion, and subsequently a speed of the fan (9) is controlled to a required speed optionally on the basis of the apportioning proportion, wherein the apportioning proportion is controlled by a control unit (15) on the basis of a non-fuzzy logic algorithm.

A compressor includes a cylinder block having a first bore and a cylinder head overlapping the cylinder block. The cylinder head has a second bore aligned with the first bore. The second bore is separated into a plurality of distinct regions including a suction region and an economizer region. A plurality of valves includes a suction valve selectively operable to fluidly couple the suction region and the first bore, and an economizer valve selectively operable to fluidly couple the economizer region and the first bore.

A method for cooling an assembly (1) for compressing a gas containing a housing (2) having a plurality of elements for compressing gas, the method comprising: allowing a cooling air flow (21) to flow from an environment into a first section 3 of a housing (2); passing the cooling air flow (21) through a plurality of coolers (14, 16, 18) that are arranged in a central section (5) of the housing (2), the cooling air flow (21) being passed from the first section (3) to a second section (4) of the housing (2); allowing the cooling air flow (21) to flow out from the second section (4) of the housing (2) into the environment.

A working fluid circuit includes a compressor, an oil sump, and an oil injection system. The compressor compresses working fluid into a compressed working fluid. The oil injection system has an oil pathway that is connected to the oil sump and to a suction pathway of the compressor. The oil pathway injects the oil from the oil sump into the suction pathway to cool the working fluid in the suction pathway. A method of controlling a working fluid circuit includes suctioning working fluid into a compressor, compressing the working fluid, and discharging the working fluid from the compressor. The method also includes separating oil from the working fluid and supplying and injecting, via an oil pathway, the oil into a suction pathway of the compressor. Gaseous refrigerant dissolved in the oil is liberated from the oil to provide cooling to the working fluid in the suction pathway.