A refrigeration system includes an evaporator configured to receive a flow of refrigerant and transfer heat into the refrigerant within the evaporator to provide cooling for a temperature-controlled space, an expansion valve operable to modulate the flow of refrigerant into the evaporator, a liquid level sensor configured to measure a level of liquid accumulated within a component of the refrigeration system, and a controller configured to operate the expansion valve to increase the flow of refrigerant into the evaporator or decrease the flow of refrigerant into the evaporator based on the level of liquid measured by the liquid level sensor.

A refrigeration cycle apparatus includes a plurality of outdoor units. Each of the plurality of outdoor units includes an outdoor heat exchanger, a compressor, and a sensor to detect the quantity of refrigeration oil in the outdoor unit. A controller has a first operation mode in which a part of the plurality of outdoor units is operated and another outdoor unit is stopped; and a second operation mode in which all of the plurality of outdoor units are operated. In the first operation mode, when the operating time of an operating outdoor unit exceeds a prescribed time and the quantity of refrigeration oil in the compressor of the operating outdoor unit is equal to or larger than a prescribed quantity, the controller stops the operating outdoor unit and makes a switch to bring a stopped outdoor unit of the plurality of outdoor units into operation.

A cooling system uses P-traps to address the oil return issues that result from a vertical separation between a compressor and a heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. T-connections are coupled to the P-traps to allow the oil to drain out of the P-traps. The oil may then be collected and returned to the compressor.

A cooling system uses P-traps to address the oil return issues that result from a vertical separation between the compressor and the high side heat exchanger. Generally, the vertical piping that carries the refrigerant from the compressor to the high side heat exchanger includes P-traps installed at various heights to capture oil in the refrigerant and to prevent that oil from flowing back to the compressor. As oil collects in the P-traps, the refrigerant begins to push the oil upwards until the oil reaches the high side heat exchanger. Multiple piping of different sizes may be used depending on a discharge pressure of the compressor. When the discharge pressure is higher, a larger piping may be used direct the oil and refrigerant to the high side heat exchanger.

A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

The present disclosure provides a compressor with an oil equalizing pipe, a parallel compressor set, and an oil equalizing method. The compressor includes at least one oil equalizing pipe, an opening at one end of the oil equalizing pipe is formed in a target oil level of an oil sump, and the opening at the other end of the oil equalizing pipe is formed in a suction port; and when the oil level of the oil sump of the compressor is higher than the target oil level, the extra oil enters the suction port through the oil equalizing pipe. Compared with the prior art, the present disclosure has the advantages that, when the compressor is running, the gas in the suction port flows, so that the pressure at the suction port is less than the pressure on the surface of the oil sump; when the oil level of the oil sump of the compressor is higher than the target oil level, the extra oil enters the suction port through the oil equalizing pipe under the action of the above pressure difference, a part of the oil enters vortex and is discharged from the compressor via the exhaust port, and the oil discharged from the compressor returns to the other compressor lack of oil through a pipeline, thereby achieving oil balance between different compressors.

A refrigerating cycle apparatus is equipped with a plurality of outdoor units, each of which includes at least one high-pressure type compressor with refrigerant and lubricating oil stored therein. A discharge pipe of the respective compressor is connected to a main discharge pipe for jointly discharging refrigerant and oil to the indoor unit. A suction pipe of the respective compressors is connected for returning the refrigerant and the oil from the indoor unit to the compressor. Each outdoor unit comprises a first oil balancing circuit connected between a side surface of the casing of the respective compressor and the main discharge pipe for allowing a flowing-in of the exceeding oil from the casing of the compressor. In another embodiment, each outdoor unit may include a second oil balancing circuit connected between a side surface of the casing of the respective compressor and the main suction pipe.

A cooling system drains oil from low side heat exchangers to vessels and then uses compressed refrigerant to push the oil in the vessels back towards a compressor. Generally, the cooling system operates in three different modes of operation: a normal mode, an oil drain mode, and an oil return mode. During the normal mode, a primary refrigerant is cycled to cool one or more secondary refrigerants. As the primary refrigerant is cycled, oil from a compressor may mix with the primary refrigerant and become stuck in a low side heat exchanger. During the oil drain mode, the oil in the low side heat exchanger is allowed to drain into a vessel. During the oil return mode, compressed refrigerant is directed to the vessel to push the oil in the vessel back towards a compressor.

The present disclosure relates to an oil flow switch, comprising a float device connected to a circulating oil passage and a floating liquid level switch element provided in the float device, wherein the float device comprises an oil inlet, an oil outlet, and a float chamber provided between the oil inlet and the oil outlet, the floating liquid level switch element is provided in the float chamber, and the float device is provided with a channel in communication with the float chamber. The oil flow switch according to the present disclosure may avoid a false alarm of the oil level switch and meanwhile mitigate disturbance to the float caused by liquid level fluctuation to reduce friction between the float and the sleeve rod. Further, a lubrication system with the above oil.

A method and device for adjusting an oil volume of a compressor of a multi-split system. The method comprises the following steps: (S1) during an operation of a multi-split system, detecting at a first pre-set time interval whether an oil volume of a compressor is insufficient; (S2) if the oil volume of the compressor is insufficient, controlling an oil volume adjusting unit to turn on for a second pre-set time and then turn off; (S3) acquiring a total turn-on time of the oil volume adjusting unit, and determining whether the total turn-on time exceeds a pre-set value; (S4) if the total turn-on time exceeds the pre-set value and it has not been detected over a continuous third pre-set time that the oil volume of the compressor is insufficient, recycling oil back to an oil storage tank by controlling a switch unit and the oil volume adjusting unit.