An embodiment heat pump system for a vehicle includes a compressor that compresses a refrigerant, a condenser connected to the compressor through a refrigerant line that condenses the refrigerant by heat-exchanging the refrigerant with a coolant, an evaporator connected to the condenser through the refrigerant line that evaporates the refrigerant, a gas injection device that selectively expands and flows the refrigerant and selectively supplies a portion of the supplied refrigerant to the compressor, a first refrigerant connection line having a first end connected to the refrigerant line and a second end connected to the gas injection device, a chiller that adjusts a temperature of the coolant by heat-exchanging the refrigerant introduced through the first refrigerant connection line with the coolant, and a second refrigerant connection line having a first end connected to the refrigerant line and a second end connected to the gas injection device.

A heat treatment module for a heat treatment system of a vehicle is disclosed. The heat treatment module includes a first heat exchanger, a second heater, and an internal heat exchanger. The first heat exchanger and the second heat exchanger both are configured to create an exchange of heat between a refrigerant and a heat transfer liquid. The internal heat exchanger is configured to create an exchange of heat within the refrigerant, which in heat treatment system is subjected to two different temperature levels. The heat treatment module includes an expansion member that is at least secured to the first heat exchanger and/or the second heat exchanger.

A first expansion valve is provided in a first refrigerant circulation passage through which the refrigerant discharged from a compressor is able to circulate by passing sequentially through an external heat exchanger and an evaporator and returning to the compressor. A second expansion valve is provided in a second refrigerant circulation passage through which the refrigerant discharged from the compressor is able to circulate by passing sequentially through an auxiliary condenser and the external heat exchanger and returning to the compressor. The second expansion valve regulates the valve opening degree such that the refrigerant state at an inlet side of the compressor during a heating operation is in a range where the dryness of refrigerant is greater than or equal to 0.9 and the superheat of refrigerant is less than or equal to 5 C.

Provided is a combination valve unit having an improved structure and capable of performing both a pressure relief function for cooling and a pressure relief function for dehumidification. In addition, disclosed is a vehicle heat pump system capable of improving dehumidification performance by actively controlling the refrigerant flow distribution. The combination valve unit serves as a refrigerant throttling means in a vehicle heat pump system, and forms the inlet for a cooling pressure relief unit for performing indoor cooling and the inlet for a dehumidification pressure relief unit for performing indoor dehumidification, respectively.

A refrigerant circulation system which circulates CO.sub.2-containing refrigerant therethrough includes a compressor which compresses the refrigerant, a motor, a motor speed sensor which detects a rotational speed of the motor, and a control device which controls at least the motor. The motor includes a rotor, a stator, a rotation shaft coupled to the rotor, and slide bearings supporting the rotation shaft and being lubricated using the refrigerant compressed by the compressor, and is configured so that the refrigerant passing through the motor expands after flowing out of the slide bearings and is used for cooling one of the rotor and the stator. The motor further includes a flow rate adjustment mechanism which adjusts a flow rate of the refrigerant. The control device controls the flow rate adjustment mechanism to adjust the flow rate of the refrigerant according to the rotational speed detected by the motor speed sensor.

An embodiment thermal management system of a vehicle includes an air supply device that draws and supplies ambient air. An air cycle apparatus connected to the air supply device that compresses or expands the air to be changed to a high or low temperature air. An air distribution device is connected to the air cycle apparatus and a cabin room connected to the air distribution device that receives the high or low temperature air. A first heat-exchanger connected to the air cycle apparatus performs heat-exchange on the high temperature air and a second heat-exchanger connected to the first heat-exchanger and the air cycle apparatus performs heat-exchange on the air. The second heat-exchanger and the air distribution device are selectively connected and the air having heat-exchanged while passing through the second heat-exchanger is selectively supplied to the air distribution device.

The present invention provides a vapor injection module having a first expansion device that either stops or expands the flow of condensed refrigerant and sends it to a gas-liquid separator. The gas-liquid separator then separates the refrigerant into gas and liquid parts. A second expansion device allows the condensed refrigerant to pass through, expand it, or expand the liquid refrigerant from the separator.

A heat pump system for a vehicle improves cooling and heating performance by applying a gas injection device that selectively operates in an air conditioning mode of vehicle interior to increase the flow rate of the refrigerant. The heat pump system is provided to minimize the cooling and heating load and simultaneously improve the overall performance and efficiency of the system by controlling the flow direction of the refrigerant introduced into the gas injection device according to the cooling and heating load.