Air conditioning system

Abstract

To provide an air conditioning system which enables heating operation even during defrosting operation.SOLUTION: An air conditioning system includes a heat pump unit 1 which has an indoor heat exchanger 13 and an outdoor heat exchanger 15 and radiates heat in the indoor heat exchanger 13 and absorbs heat in the outdoor heat exchanger 15 during heating operation. The outdoor heat exchanger 15 is disposed facing a heat radiating heat exchanger 23 in a warming system unit 2 including the heat radiating heat exchanger 23. A blower fan 3 which may generate airflow in an area ranging from the heat radiating heat exchanger 23 to the outdoor heat exchanger 15 is disposed. When frost is formed in the outdoor heat exchanger 15, the blower fan 3 is operated on the condition that a temperature of the heat radiating heat exchanger 23 is higher than or equal to a predetermined temperature and provides heat of the heat radiating heat exchanger 23 to the outdoor heat exchanger 15 and thereby melt frost of the outdoor heat exchanger 15.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an air conditioning system mounted in, for example, a vehicle. [Background technology]

[0002] Conventionally, a heat pump type air conditioning system has been known as an air conditioning system mounted on, for example, a hybrid vehicle, an electric vehicle, etc. This heat pump type air conditioning system includes a heat medium circulation circuit in which a compressor, an indoor heat exchanger, an expansion valve, an outdoor heat exchanger, etc. are connected by heat medium piping.

[0003] During cooling operation, the heat medium circulates through the compressor, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger in that order, thereby cooling the air inside the vehicle cabin by absorbing heat due to evaporation of the heat medium in the indoor heat exchanger. On the other hand, during heating operation, the heat medium circulates through the compressor, the indoor heat exchanger, the expansion valve, and the outdoor heat exchanger in that order, thereby warming the air inside the vehicle cabin by dissipating heat due to condensation of the heat medium in the indoor heat exchanger. In addition, when frost forms on the outdoor heat exchanger during heating operation, a defrosting operation is performed. As an example of this defrosting operation, as disclosed in Patent Document 1, for example, the circulating direction of the heat medium is switched and the high-temperature heat medium discharged from the compressor is caused to flow into the outdoor heat exchanger to melt the frost. In addition, in an air conditioning system equipped with a heating circuit and a cooling circuit, there is also one in which the frost is melted by mixing the heat medium from the heating circuit to the cooling circuit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-507707 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the defrosting operation disclosed in Patent Document 1, the high-temperature heat medium discharged from the compressor flows through the outdoor heat exchanger, so that the heat medium cannot absorb heat by evaporation in the outdoor heat exchanger. In other words, heating operation cannot be performed during the defrosting operation, and as a result, there is a possibility that the comfort of the air-conditioned space (the passenger compartment space in the case of a vehicle) may be impaired. The same applies to the above-mentioned system in which the heat medium is mixed from the heating circuit to the cooling circuit.

[0006] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an air conditioning system that enables heating operation even during defrosting. [Means for solving the problem]

[0007] The solution of the present invention for achieving the above object is based on an air conditioning system including a heat pump unit that has an indoor heat exchanger and an outdoor heat exchanger and performs heat dissipation in the indoor heat exchanger and heat absorption in the outdoor heat exchanger during heating operation, the outdoor heat exchanger is disposed opposite to a heat dissipation heat exchanger in a heating unit that has a heat dissipation heat exchanger, a blower fan capable of generating an airflow from the heat dissipation heat exchanger to the outdoor heat exchanger is disposed, and the air conditioning system includes a temperature detection means capable of detecting a temperature of the heat dissipation heat exchanger or a temperature correlated to the temperature of the heat dissipation heat exchanger, and a blower fan control unit that operates the blower fan when frost forms on the outdoor heat exchanger and the temperature detected by the temperature detection means is equal to or higher than a predetermined temperature.

[0008] With this specification, when frost forms on the outdoor heat exchanger during heating operation by the heat pump unit, if the temperature of the heat dissipation heat exchanger of the warming unit detected by the temperature detection means or a temperature correlated to the temperature of the heat dissipation heat exchanger is equal to or higher than a predetermined temperature, the blower fan operates under this condition. The operation of the blower fan generates an airflow from the heat dissipation heat exchanger to the outdoor heat exchanger of the heat pump unit, and the heat of the heat dissipation heat exchanger is given to the outdoor heat exchanger, melting the frost on the outdoor heat exchanger. In other words, since there is no need to switch the circulation direction of the heat medium and flow the high-temperature heat medium discharged from the compressor to the outdoor heat exchanger to melt the frost, the outdoor heat exchanger can be defrosted while continuing the heating operation. As a result, the comfort of the air-conditioned space can be maintained. Effect of the Invention

[0009] In the present invention, when frost forms on the outdoor heat exchanger of the heat pump unit, the blower fan operates on the condition that the temperature of the heat dissipation heat exchanger of the heating unit or a temperature correlated to the temperature of the heat dissipation heat exchanger is equal to or higher than a predetermined temperature, generating an airflow from the heat dissipation heat exchanger to the outdoor heat exchanger. This makes it possible to defrost the outdoor heat exchanger while continuing heating operation, thereby maintaining the comfort of the air-conditioned space. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a circuit diagram showing a schematic configuration of a heat pump unit and a heating unit. [Diagram 2] 2 is a block diagram showing an outline of a control system of the heat pump unit. FIG. [Diagram 3] FIG. 4 is a flowchart showing a procedure of defrosting control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention is applied to an air conditioning system mounted on a hybrid vehicle.

[0012] -Outline of air conditioning system configuration- Fig. 1 is a circuit diagram showing a schematic configuration of a heat pump unit 1 and a heating unit 2 according to this embodiment. In Fig. 1, the right side of the dashed dotted line is the inside of the vehicle compartment, and the left side is the outside of the vehicle compartment.

[0013] As shown in Fig. 1, the heat pump unit 1 includes a heat medium circulation circuit 11 through which a heat medium circulates. The heat medium circulation circuit 11 includes a compressor 12, an indoor heat exchanger 13, an expansion valve 14, and an outdoor heat exchanger 15, etc., which are connected by heat medium piping. In addition to these devices, the heat medium circulation circuit 11 also includes a switching valve (not shown) that switches the circulation direction of the heat medium in the heat medium circulation circuit 11, a receiver, etc.

[0014] As a result, during cooling operation, the heat pump unit 1 cools the air inside the vehicle cabin by absorbing heat associated with evaporation of the heat medium in the indoor heat exchanger 13, as the heat medium circulates through the compressor 12, the outdoor heat exchanger 15, the expansion valve 14, and the indoor heat exchanger 13 in that order. On the other hand, during heating operation, the heat pump unit 1 warms the air inside the vehicle cabin by releasing heat associated with condensation of the heat medium in the indoor heat exchanger 13, as the heat medium circulates through the compressor 12, the indoor heat exchanger 13, the expansion valve 14, and the outdoor heat exchanger 15 in that order.

[0015] The compressor 12 compresses and discharges the drawn heat medium, and is configured as an electric compressor driven by an electric motor (not shown).

[0016] The indoor heat exchanger 13 is disposed in an air conditioning duct that forms an air passage for guiding conditioned air into the vehicle cabin, and exchanges heat between the air flowing through the air conditioning duct and the heat medium. That is, during cooling operation, the air flowing through the air conditioning duct is cooled by the heat absorption associated with the evaporation of the heat medium in the indoor heat exchanger 13. On the other hand, during heating operation, the air flowing through the air conditioning duct is heated by the heat release associated with the condensation of the heat medium in the indoor heat exchanger 13.

[0017] An air conditioning blower that generates an air flow in the air conditioning duct is disposed in the air conditioning duct, and the air is passed through the indoor heat exchanger 13 by the operation of the air conditioning blower, where the temperature of the air is adjusted and supplied to the vehicle interior. An inside air intake port that takes in the air inside the vehicle interior (inside air) and an outside air intake port that takes in the air outside the vehicle interior (outside air) are disposed on the most upstream side (windward side) of the air conditioning duct. An inside / outside air switching door is rotatably attached inside the inside air intake port and the outside air intake port. The operation of the inside / outside air switching door switches the intake port mode between the inside air circulation mode and the outside air introduction mode. A defroster outlet, a face outlet, and a foot outlet are disposed on the most downstream side (downwind side) of the air conditioning duct. An outlet switching door is rotatably attached inside the inside of these outlets. The blowing mode of the conditioned air is switched by the operation of the outlet switching door.

[0018] The expansion valve 14 reduces the pressure of the heat medium discharged from the compressor 12 and condensed. That is, during cooling operation, the heat medium condensed by the outdoor heat exchanger 15 is reduced in pressure by the expansion valve 14. On the other hand, during heating operation, the heat medium condensed by the indoor heat exchanger 13 is reduced in pressure by the expansion valve 14.

[0019] The outdoor heat exchanger 15 exchanges heat between the heat medium and the outside air. That is, during cooling operation, the heat medium discharged from the compressor 12 is condensed by the outdoor heat exchanger 15. On the other hand, during heating operation, the heat medium decompressed by the expansion valve 14 is evaporated by the outdoor heat exchanger 15.

[0020] The warming unit 2 includes a unit circuit 21 through which a heat medium circulates. The unit circuit 21 includes an HV unit 22 and a heat dissipation heat exchanger 23 connected by a heat medium pipe.

[0021] The HV unit 22 includes various motors (such as a motor for driving) and inverters (such as an inverter for controlling a motor). For this reason, each device that constitutes the HV unit 22 generates heat during operation.

[0022] The heat dissipation heat exchanger 23 dissipates heat from the heat medium by exchanging heat between the heat medium circulating in the unit circuit 21 and the outside air. In other words, heat from each device constituting the HV unit 22 is dissipated from the heat dissipation heat exchanger 23 via the heat medium.

[0023] One of the features of this embodiment is that the heat dissipation heat exchanger 23 of the heating unit 2 and the outdoor heat exchanger 15 of the heat pump unit 1 are arranged to face each other. In other words, they are arranged so that the air that has passed through the heat dissipation heat exchanger 23 passes directly through the outdoor heat exchanger 15.

[0024] An electric blower fan 3 is disposed facing the outdoor heat exchanger 15. The extending direction of the rotation shaft of the blower fan 3 coincides with the opposing direction of the heat dissipation heat exchanger 23 and the outdoor heat exchanger 15. When the blower fan 3 operates to generate an airflow, the air passes from the heat dissipation heat exchanger 23 to the outdoor heat exchanger 15 (see the arrow indicated by the dashed line in FIG. 1).

[0025] As sensors provided in the heat pump unit 1 and the heating unit 2, a first temperature sensor 16 (see FIG. 2 showing an outline of the control system of the heat pump unit 1) is attached to the indoor heat exchanger 13 of the heat pump unit 1. This first temperature sensor 16 is a sensor for detecting the occurrence of frost in the outdoor heat exchanger 15. In other words, when frost occurs in the outdoor heat exchanger 15 during heating operation, the amount of heat absorbed by the evaporation of the heat medium in the outdoor heat exchanger 15 rapidly decreases, and the temperature of the indoor heat exchanger 13 also rapidly decreases. By detecting this change with the first temperature sensor 16, it is possible to detect the occurrence of frost in the outdoor heat exchanger 15. As shown in FIG. 2, information on the temperature of the indoor heat exchanger 13 detected by this first temperature sensor 16 is transmitted to the air conditioner ECU 4 as a temperature detection signal. Furthermore, the first temperature sensor 16 may be attached to the fins or piping of the indoor heat exchanger 13, or may be disposed inside the piping of the indoor heat exchanger 13 so as to detect the temperature of the heat medium flowing inside the indoor heat exchanger 13.

[0026] A second temperature sensor (temperature detection means in the present invention) 24 (see FIG. 2) is attached to the heat dissipation heat exchanger 23. This second temperature sensor 24 is a sensor for detecting the temperature of the heat dissipation heat exchanger 23. As shown in FIG. 2, information on the temperature of the heat dissipation heat exchanger 23 detected by this second temperature sensor 24 is transmitted to the air conditioner ECU 4 as a temperature detection signal. The second temperature sensor 24 may be attached to the fins or piping of the heat dissipation heat exchanger 23, or may be disposed inside the piping of the heat dissipation heat exchanger 23 so as to detect the temperature of the heat medium flowing inside the heat dissipation heat exchanger 23.

[0027] As shown in FIG. 2, the air conditioner ECU 4 includes a frost formation determination unit 41 and a blower fan control unit 42 as functional units realized by the control program.

[0028] The frost determination unit 41 is a functional unit that receives a temperature detection signal from the first temperature sensor 16 and determines whether or not frost has formed in the outdoor heat exchanger 15 based on a change in the temperature of the indoor heat exchanger 13. The change in temperature of the indoor heat exchanger 13 for determining that frost has formed in the outdoor heat exchanger 15 is set in advance by experiment or simulation.

[0029] The blower fan control unit 42 is a functional unit that receives a temperature detection signal from the second temperature sensor 24, and when it is determined by the frost determination unit 41 that frost has formed on the outdoor heat exchanger 15, outputs an operation command signal to the blower fan 3 on condition that the temperature of the heat dissipation heat exchanger 23 (the temperature detected by the second temperature sensor 24) is equal to or higher than a predetermined temperature. Here, the predetermined temperature (the temperature of the heat dissipation heat exchanger 23), which is the condition for outputting the operation command signal to the blower fan 3, is set in advance by experiment or simulation as a temperature at which the frost adhering to the outdoor heat exchanger 15 can be melted within a short period of time.

[0030] -Defrost control- Next, defrosting control in the air conditioning system configured as described above will be described with reference to the flowchart of Fig. 3. This flowchart is repeatedly performed at predetermined time intervals during heating operation of the heat pump unit 1.

[0031] First, in step ST1, it is determined whether or not frost has formed on the outdoor heat exchanger 15 of the heat pump unit 1. This determination is made by the frost determination unit 41 as described above, which receives a temperature detection signal from the first temperature sensor 16 and determines whether or not frost has formed on the outdoor heat exchanger 15 based on a change in the temperature of the indoor heat exchanger 13.

[0032] If no frost has formed on the outdoor heat exchanger 15 and the result of step ST1 is NO, the process proceeds to step ST2, where it is determined that no defrosting operation (operation of the blower fan 3) is necessary, and the heating operation of the heat pump unit 1 continues.

[0033] On the other hand, if frost has formed on the outdoor heat exchanger 15 and the determination in step ST1 is YES, the process proceeds to step ST3, in which it is determined whether the temperature of the heat dissipation heat exchanger 23 of the heating unit 2 is equal to or higher than the predetermined value T1. This determination is made by the blower fan control unit 42 as described above, by receiving a temperature detection signal from the second temperature sensor 24.

[0034] If the temperature of the heat dissipation heat exchanger 23 of the heating unit 2 is lower than the predetermined value T1 and the result of step ST3 is NO, a conventional defrosting operation is started by switching the circulation direction of the heat medium. That is, the heat medium circulates in the order of the compressor 12, the outdoor heat exchanger 15, the expansion valve 14, and the indoor heat exchanger 13, and the high-temperature heat medium is caused to flow through the outdoor heat exchanger 15 to melt the frost.

[0035] On the other hand, if the temperature of the heat dissipation heat exchanger 23 of the heating unit 2 is equal to or higher than the predetermined value T1 and the determination in step ST3 is YES, the process proceeds to step ST5, where an operation command signal is output to the blower fan 3 to operate the blower fan 3. This generates an airflow from the heat dissipation heat exchanger 23 of the heating unit 2 to the outdoor heat exchanger 15 of the heat pump unit 1 (see the dashed arrow in FIG. 1), and the heat of the heat dissipation heat exchanger 23 is given to the outdoor heat exchanger 15, causing the frost on the outdoor heat exchanger 15 to melt.

[0036] The above operations are repeated.

[0037] -Effects of the embodiment- As described above, in this embodiment, when frost forms on the exterior heat exchanger 15 of the heat pump unit 1, the blower fan 3 operates on condition that the temperature of the heat dissipation heat exchanger 23 of the heating unit 2 is equal to or higher than the predetermined value T1, and air is blown from the heat dissipation heat exchanger 23 to the exterior heat exchanger 15. This makes it possible to defrost the exterior heat exchanger 15 while continuing the heating operation, thereby maintaining the comfort of the vehicle interior space (air-conditioned space).

[0038] In addition, in this embodiment, it is possible to suppress an increase in costs because there is no need to add a new device for defrosting the outdoor heat exchanger 15. Also, since the heat of the heat dissipation heat exchanger 23, which was conventionally wasted (discharged into the atmosphere), is effectively utilized to defrost the outdoor heat exchanger 15, it is possible to achieve significant energy savings.

[0039] -Other embodiments- The present invention is not limited to the above-described embodiment, and all modifications and applications within the scope of the claims and equivalents thereto are possible.

[0040] For example, in the above embodiment, the present invention has been described as being applied to an air conditioning system mounted on a hybrid vehicle, but the present invention is not limited to this, and may also be applied to an air conditioning system mounted on an electric vehicle or a plug-in hybrid vehicle.

[0041] Furthermore, in the above embodiment, the occurrence of frost on the outdoor heat exchanger 15 is determined based on the temperature of the indoor heat exchanger 13. However, the present invention is not limited to this, and the occurrence of frost on the outdoor heat exchanger 15 may be determined optically. For example, a light-projecting element may be disposed on one side of the outdoor heat exchanger 15 and a light-receiving element may be disposed on the other side, and the occurrence of frost on the outdoor heat exchanger 15 may be determined based on a change in the amount of light received by the light-receiving element.

[0042] In the above embodiment, the second temperature sensor 24 directly detects the temperature of the heat dissipation heat exchanger 23. However, the present invention is not limited to this, and a temperature correlated with the temperature of the heat dissipation heat exchanger 23 may be detected. For example, the temperature of the heat medium flowing into the heat dissipation heat exchanger 23 or the temperature of the HV unit 22 may be detected. [Industrial Applicability]

[0043] The present invention is applicable to heat pump type air conditioning systems mounted on hybrid vehicles, electric vehicles, and the like. [Explanation of symbols]

[0044] 1... Heat pump unit 13... Indoor heat exchanger 15... Outdoor heat exchanger 2... Heating unit 23... Heat exchanger for heat dissipation 3... Blower fan 24... second temperature sensor (temperature detection means) 42... blower fan control section

Claims

[Claim 1] An air conditioning system including a heat pump unit having an indoor heat exchanger and an outdoor heat exchanger, the heat pump unit releasing heat in the indoor heat exchanger and absorbing heat in the outdoor heat exchanger during heating operation, The outdoor heat exchanger is disposed opposite a heat dissipation heat exchanger in a heating unit having a heat dissipation heat exchanger, a blower fan capable of generating an airflow from the heat dissipation heat exchanger to the outdoor heat exchanger is provided; a temperature detection means capable of detecting a temperature of the heat dissipation heat exchanger or a temperature correlated to the temperature of the heat dissipation heat exchanger; and a blower fan control unit that operates the blower fan when frost forms on the outdoor heat exchanger, on the condition that the temperature detected by the temperature detection means is equal to or higher than a predetermined temperature.

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