Air conditioner for vehicle

Abstract

To provide an air conditioner for a vehicle which can improve measurement accuracy of an air temperature on the leeward side of a heater core without adding a sensor.SOLUTION: A control device 200 enabling control in a hot gas heating mode of flowing a part of a refrigerant having passed through a compressor 11 into a heater core 12 and flowing a residual refrigerant into a bypass passage calculates an air temperature Thp on the leeward side of the heater core 12, on the basis of a temperature Tcxin of a refrigerant flowing into an inlet side 12a of the heater core 12, a temperature Tci of a refrigerant flowing out from an outlet side of the heater core 12, an overheating degree of the refrigerant flowing out from the outlet side of the heater core 12, and SHout, in the hot gas heating mode.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an air conditioner for a vehicle. [Background technology]

[0002] 2. Description of the Related Art Air conditioners using a heat pump are known as air conditioners for electric vehicles (EVs) that do not have a combustion heat source such as an engine or for vehicles that have a small amount of heat from a combustion heat source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 672137 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an air conditioner for a vehicle that can improve the measurement accuracy of the air temperature on the downwind side of a heater core without adding an additional sensor. [Means for solving the problem]

[0005] According to one aspect of the present invention, a vehicle air conditioning system is configured so that a refrigerant circulates through a compressor, a heater core that heats air supplied to a vehicle cabin, a pressure reducing device, a low-temperature side heat exchanger that causes a refrigerant to absorb heat from a heat medium absorbed from an on-board heat-generating device, and an accumulator, and the vehicle air conditioning system is equipped with a refrigerant circuit including a bypass path in which the refrigerant that has passed through the compressor bypasses the heater core and flows into the suction side of the compressor, and a control device capable of control in a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor flows into the heater core and the remaining refrigerant flows into the bypass path, and in the hot gas heating mode, the control device calculates the air temperature on the downwind side of the heater core based on the temperature of the refrigerant flowing into the inlet side of the heater core, the temperature of the refrigerant flowing out from the outlet side of the heater core, and the degree of superheat of the refrigerant flowing out from the outlet side of the heater core. Effect of the Invention

[0006] According to the present invention, it is possible to provide a vehicle air conditioner that can improve the measurement accuracy of the air temperature on the downwind side of the heater core without adding an additional sensor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an outline of a configuration example of a vehicle air conditioner, and is a diagram showing an example of a state of the vehicle air conditioner when hot gas heating is performed. [Diagram 2] FIG. 2 is a block diagram showing an example of a control device in a vehicle air conditioner. [Diagram 3] FIG. 3 is a diagram showing an example of a flowchart illustrating a processing procedure for calculating the heating capacity when the hot gas heating mode is being executed in the vehicle air conditioner. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Configuration of vehicle air conditioning system] Overview of Vehicle Air Conditioning System The vehicle air conditioner of this embodiment is configured to be able to improve the measurement accuracy of the air temperature on the downwind side of the heater core without adding an additional sensor.

[0009] FIG. 1 is an explanatory diagram showing an outline of a configuration example of a vehicle air conditioner 1 according to this embodiment.

[0010] The vehicle air conditioner 1 includes a refrigerant circuit 10 configured to circulate a refrigerant. The refrigerant may be, but is not limited to, hydrofluoroolefin. The vehicle air conditioner 1 also includes a battery temperature control circuit 40 configured to circulate a heat transfer medium, such as a fluid such as a coolant.

[0011] The vehicle air conditioner 1 also includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 100. The vehicle air conditioner 1 also includes a control device 200 (see FIG. 2) that controls the operation of various sensors and each part of the vehicle air conditioner 1. The operation of the vehicle air conditioner 1 is controlled based on the detection values ​​of the various sensors, various requests, etc.

[0012] <Refrigerant circuit> The refrigerant circuit 10 includes a compressor 11 that compresses a gaseous refrigerant to a high temperature and high pressure and then discharges it, a heater core 12 that is housed in a case 110 of the HVAC unit 100 and heats the air to be supplied to the vehicle interior, pressure reducing devices 13a, 13b, 13c, and 13d such as expansion valves that expand the liquid refrigerant to a low pressure, a low-temperature side heat exchanger 14 that evaporates the low-temperature and low-pressure liquid refrigerant to absorb heat, an accumulator 15, a cooler core 16 that is housed in the case 110 of the HVAC unit 100 and cools the air to be supplied to the vehicle interior, and a radiator 17 as an exterior heat exchanger. The refrigerant circuit 10 is configured to function as a heat pump that circulates the refrigerant and repeats compression, condensation, expansion, and evaporation.

[0013] In the low-temperature side heat exchanger 14, the refrigerant exchanges heat with a heat medium circulating in the battery temperature control circuit 40. In the example shown in the figure, the low-temperature side heat exchanger 14 includes a refrigerant passage 14a through which the refrigerant circulating in the refrigerant circuit 10 passes, and a heat medium passage 14b through which the heat medium circulating in the battery temperature control circuit 40 passes.

[0014] The elements of the refrigerant circuit 10 are connected by refrigerant flow paths 10a, 10b, 10c, 10e, 10f, 10g, 10j, 10k, 10m, 10n, 10p, 10q, 10r, 10s, 10t, 10u, 10v, and 10w.

[0015] A discharge side 11a of the compressor 11 is connected to an inlet side 12a of a heater core 12 via a refrigerant flow path 10a connected thereto, a branch point 18a, and a refrigerant flow path 10b downstream of the branch point 18a.

[0016] The discharge side 11a of the compressor 11 is connected to the inlet side 15a of the accumulator 15 via the refrigerant flow path 10a, the branch point 18a, the refrigerant flow path 10c, the junction 19a, the refrigerant flow path 10e, the junction 19b, and the downstream refrigerant flow path 10f, which are connected to the discharge side 11a. A pressure reducing device 13a is installed on the path of the refrigerant flow path 10c.

[0017] An outlet side 15b of the accumulator 15 is connected to a suction side 11b of the compressor 11 via a refrigerant flow path 10g connected thereto.

[0018] The outlet side 12b of the heater core 12 is connected to the inlet side 16a of the cooler core 16 via the refrigerant flow path 10j, the branch point 18b, the refrigerant flow path 10k, the junction 19d, the refrigerant flow path 10m, the branch point 18c, and the downstream refrigerant flow path 10n. A flow path opening / closing valve 20a is provided on the path of the refrigerant flow path 10k. A pressure reducing device 13b is provided on the path of the refrigerant flow path 10n.

[0019] The outlet side 16b of the cooler core 16 is connected to the inlet side 15a of the accumulator 15 via the refrigerant flow paths 10p, the junction 19e, the refrigerant flow paths 10q, the junction 19a, the refrigerant flow paths 10e, the junction 19b, and the downstream refrigerant flow path 10f. A check valve 21b is provided on the path of the refrigerant flow path 10q to prevent the refrigerant from flowing back to the cooler core 16.

[0020] The outlet side 12b of the heater core 12 is connected to an inlet of a refrigerant passage 14a of the low-temperature side heat exchanger 14 via a refrigerant passage 10j, a branch point 18b, a refrigerant passage 10k, a junction 19d, a refrigerant passage 10m, a branch point 18c, and a downstream refrigerant passage 10r, which are connected to the outlet side 12b. A pressure reducing device 13c is installed on the path of the refrigerant passage 10r.

[0021] The outlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 is connected to the inlet side 15a of the accumulator 15 via a refrigerant passage 10s connected thereto, a junction 19b, and a refrigerant passage 10f downstream of the junction 19b. A passage opening / closing valve 20d is provided on the path of the refrigerant passage 10s.

[0022] An outlet side 12b of the heater core 12 is connected to an inlet side 17a of a radiator 17 via a refrigerant flow path 10j connected thereto, a branch point 18b, and a downstream refrigerant flow path 10t. A pressure reducing device 13d is installed on the path of the refrigerant flow path 10t.

[0023] The outlet side 17b of the radiator 17 is connected to the inlet side 15a of the accumulator 15 via the refrigerant flow path 10u, the branch point 18d, the refrigerant flow path 10v, the junction 19e, the refrigerant flow path 10q, the junction 19a, the refrigerant flow path 10e, the junction 19b, and the refrigerant flow path 10f downstream thereof. A flow path opening / closing valve 20b is provided on the path of the refrigerant flow path 10v.

[0024] The outlet side 17b of the radiator 17 is connected to the inlet side 16a of the cooler core 16 via the refrigerant flow path 10u, the branch point 18d, the refrigerant flow path 10w, the junction 19d, the refrigerant flow path 10m, the branch point 18c, and the downstream refrigerant flow path 10n. A check valve 21c is provided on the path of the refrigerant flow path 10w to prevent the refrigerant from flowing back to the radiator 17.

[0025] The outlet side 17b of the radiator 17 is connected to the inlet of the refrigerant passage 14a of the low-temperature side heat exchanger 14 via the refrigerant flow path 10u, branch point 18d, refrigerant flow path 10w, junction 19d, refrigerant flow path 10m, branch point 18c, and the downstream refrigerant flow path 10r connected thereto.

[0026] <Battery temperature control circuit> The battery temperature control circuit 40 as an in-vehicle heat-generating device temperature control circuit includes the heat medium passage 14b of the low-temperature side heat exchanger 14 described above and a battery 41 as an in-vehicle heat-generating device. The battery 41 is provided with a battery temperature control unit for controlling the temperature of the battery 41. The battery temperature control circuit 40 can be used to adjust the temperature of the battery 41.

[0027] Note that a configuration similar to that of the battery temperature control circuit 40 can also be applied to other in-vehicle device temperature control circuits having an in-vehicle device temperature control unit for controlling the temperature of other in-vehicle devices that require temperature control in a similar manner, not limited to the battery.

[0028] In the example shown in the figure, the elements of the battery temperature control circuit 40 are connected by heat medium flow paths 40a, 40b. The inlet side 41a of the battery 41 is connected to the outlet of the heat medium passage 14b of the low-temperature side heat exchanger 14 by the heat medium flow path 40a. The outlet side 41b of the battery 41 is connected to the inlet of the heat medium passage 14b of the low-temperature side heat exchanger 14 by the heat medium flow path 40b.

[0029] On the path of the heat medium flow path 40b, a circulation pump P40 and a heat medium heater 42 are installed in this order from the upstream side. The heat medium can be circulated by the circulation pump P40, and the temperature of the battery 41 can be adjusted.

[0030] <HVAC unit> The heater core 12 and the cooler core 16 of the refrigerant circuit 10 are housed in a case 110 of the HVAC unit 100. The case 110 forms the outer shell of the HVAC unit 100, and also forms an air flow passage 120 therein.

[0031] The HVAC unit 100 also has an intake unit 130. The intake unit 130 closes either an outside air intake port that introduces outside air in the vehicle cabin or an inside air intake port that introduces inside air in the vehicle cabin, and switches the air introduced into the case 110 between outside air in the vehicle cabin (outside air intake) and inside air in the vehicle cabin (inside air circulation). The HVAC unit 100 also has a blower 140 installed adjacent to the intake unit 130 so that the air introduced into the case 110 is sent to the air flow passage 120. The blower 140 blows the air to be heat exchanged in the heater core 12 and the cooler core 16 into the vehicle cabin.

[0032] The cooler core 16 is installed at the upstream side of the air flow passage 120. A heater core passage 121 and a bypass passage 122 are formed in parallel at the downstream side of the air flow passage 120. The heater core 12 is provided in the heater core passage 121. Therefore, when the air introduced into the case 110 is guided to the heater core passage 121, the air is ventilated to the cooler core 16 and then ventilated to the heater core 12. On the other hand, when the air introduced into the case 110 is guided to the bypass passage 122, the air is ventilated to the cooler core 16 and then bypasses the heater core 12. The ratio of the air passing through the heater core passage 121 and the air passing through the bypass passage 122 is adjusted by the air mix damper 150.

[0033] Control Device FIG. 2 is an explanatory diagram showing an outline of a configuration example of the control device 200 of the vehicle air conditioner 1 according to this embodiment.

[0034] The control device 200 controls the operation of various sensors and each part of the vehicle air conditioner 1. The control device 200 is an air conditioning ECU (Electronic Control Unit) for executing various control modes of the vehicle air conditioner 1. The various control modes executed by the control device 200 include a hot gas heating mode that executes hot gas heating.

[0035] The control device 200 receives detection information from various sensors. In the hot gas heating mode, the control device 200 receives detection information from a blower temperature sensor 210, an outside air temperature sensor 220, a refrigerant temperature sensor 230, a refrigerant pressure sensor 240, and a vehicle interior temperature sensor 250. The refrigerant temperature sensor 230 is composed of a plurality of sensors that detect the refrigerant temperature at each point of the refrigerant circuit 10, and includes an inlet-side refrigerant temperature sensor 230a that detects the temperature of the refrigerant at the inlet side 12a of the heater core 12 and an outlet-side refrigerant temperature sensor 230b that detects the temperature of the refrigerant at the outlet side 12b of the heater core 12. The refrigerant pressure sensor 240 is composed of a plurality of sensors that detect the refrigerant pressure at each point of the refrigerant circuit 10, and includes an inlet-side refrigerant pressure sensor 240a that detects the pressure of the refrigerant at the inlet side 12a of the heater core 12 and an outlet-side refrigerant pressure sensor 240b that detects the pressure of the refrigerant at the outlet side 12b of the heater core 12.

[0036] The control device 200 selects a path in the refrigerant circuit 10 by opening and closing the pressure reducing devices 13a-13d and the flow passage opening and closing valves 20a, 20b based on detection information from various sensors. While selecting the path, the control device 200 controls the operation of the compressor 11, the blower 140, the air mix damper 150, the circulation pump P40, and the pressure reducing devices 13a-13d to control the amount of heat released from the refrigerant. The control device 200 also calculates the actual heating capacity value and the target heating capacity in the hot gas heating mode by appropriately using detection information from the blower temperature sensor 210, the vehicle interior temperature sensor 250, the inlet side refrigerant temperature sensor 230a, the inlet side refrigerant pressure sensor 240a, the outlet side refrigerant temperature sensor 230b, and the inlet side refrigerant pressure sensor 240a.

[0037] [Operation of vehicle air conditioning system] A specific operation of the vehicle air conditioner 1 according to this embodiment will be described.

[0038] <Hot gas heating mode> 1 shows the state of the vehicle air conditioner 1 when the outside temperature is extremely low. At this time, the vehicle interior is heated by executing the hot gas heating mode.

[0039] In the hot gas heating mode, the control device 200 fully closes the pressure reducing devices 13b and 13d and opens the flow passage opening / closing valves 20a and 20b.

[0040] As a result, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10a and 10b and passes through the heater core 12. The refrigerant that has passed through the heater core 12 flows into the refrigerant flow paths 10j, 10k, 10m, and 10r and passes through the refrigerant passage 14a of the low-temperature side heat exchanger 14. The refrigerant that has passed through the refrigerant passage 14a of the low-temperature side heat exchanger 14 flows into the refrigerant flow paths 10s and 10f and flows into the accumulator 15. The refrigerant that has flowed into the accumulator 15 flows into the refrigerant flow path 10g and then flows into the compressor 11. In other words, the refrigerant flow paths 10a, 10b, 10j, 10k, 10m, 10r, 10s, 10f, and 10g form a circulation path through which the refrigerant that has passed through the compressor 11 passes through the heater core 12.

[0041] In addition, the refrigerant discharged from the compressor 11 flows into the refrigerant flow paths 10a, 10c, 10e, and 10f and then flows into the accumulator 15. The refrigerant that flows into the accumulator 15 flows into the refrigerant flow path 10g and then flows into the compressor 11. In other words, the refrigerant flow paths 10a, 10c, 10d, 10e, 10f, and 10g form a bypass path through which the refrigerant that has passed through the compressor 11 detours without passing through the heater core 12.

[0042] The control device 200 adjusts the throttling amount of the pressure reducing device 13a to cause a portion of the refrigerant discharged from the compressor 11 to flow to the heater core 12 and the remaining refrigerant to flow to the bypass path. As a result, the vehicle interior is heated by the heat of the refrigerant dissipated in the heater core 12. Also, the refrigerant flowing through the bypass path has a higher temperature when it returns to the suction side 11b of the compressor 11 than the refrigerant passing through the heater core 12. As a result, in the hot gas heating mode, even if the outside air is extremely low temperature, the temperature of the refrigerant discharged from the compressor 11 can be increased to maintain the heating capacity.

[0043] [Control of vehicle air conditioners] Next, the control process performed by the control device 200 in the vehicle air conditioner 1 will be described with reference to FIG.

[0044] In the hot gas heating mode, the control device 200 calculates the target heating capacity TGQh, which is the heating capacity required to achieve the interior temperature set by the occupant, using the following calculation formula (1), while calculating the actual heating capacity, the measured heating capacity value Qhp, using the following calculation formula (2).

[0045] The control device 200 then compares the two to determine whether the heating capacity actual measurement value Qhp achieves the target heating capacity TGQh. If the heating capacity actual measurement value Qhp does not achieve the target heating capacity TGQh, the control device 200 controls each component of the vehicle air conditioner 1 to vary each numerical value for calculating the heating capacity actual measurement value Qhp so as to achieve the target heating capacity TGQh.

[0046] TGQh = (THO-Te) × Ga (1) TGQh: Target heating capacity (kW) THO: Target heater core downwind air temperature (℃) Te: Air temperature upwind of heater core (℃) Ga: Volume of air passing through the air flow passage 120 (m3 / s)

[0047] Qhp = (Thp - Te) × Ga (2) Qhp: Actual heating capacity (kW) Thp: Air temperature downwind of heater core (℃) Te: Air temperature upwind of heater core (℃) Ga: Volume of air passing through the air flow passage 120 (m3 / s)

[0048] The target heater core downwind air temperature THO is calculated based on the difference between the set temperature in the vehicle interior and the actual temperature measured when the target heating capacity is calculated. The air volume Ga is estimated from the blower voltage BLV of the blower 140, etc.

[0049] <Calculation process of measured heating capacity Qhp> Fig. 3 is a flowchart showing an example of a calculation process of the heating capacity actual measurement value Qhp by the control device 200. By executing the process shown in Fig. 3, the control device 200 calculates the heater core downwind side air temperature Thp by the method according to the present invention, and then calculates the heating capacity actual measurement value Qhp using the above calculation formula (2). The process will be described in detail below with reference to Fig. 3.

[0050] As shown in FIG. 3, the control device 200 calculates the degree of superheat SHout of the refrigerant flowing out from the outlet side 12b of the heater core 12 based on the temperature and pressure of the outlet side 12b of the heater core 12 (S1).

[0051] The degree of superheat SHout is calculated, for example, by determining the saturation temperature based on the pressure of the outlet side 12b of the heater core 12 and subtracting the saturation temperature from the temperature of the outlet side 12b of the heater core 12. The control device 200 holds a data table in which the pressure of the outlet side 12b of the heater core 12 and the saturation temperature correspond to each other based on the data of the ph diagram, and the saturation temperature can be determined from the pressure of the outlet side 12b of the heater core 12 by searching the data table. The saturation temperature may be calculated using a formula based on the data of the ph diagram. The degree of superheat SHout of the refrigerant at the outlet side 12b of the heater core 12 may also be calculated based on the pressure of the inlet side 12a of the heater core 12 and the temperature of the outlet side 12b of the heater core 12.

[0052] Next, the control device 200 determines whether the calculated degree of superheat SHout is equal to or greater than a predetermined value α (α>0) (S2).

[0053] Here, due to detection errors by the outlet side refrigerant temperature sensor 230b and the outlet side refrigerant pressure sensor 240b, it is difficult to accurately detect that the superheat degree SHout is 0. Therefore, due to detection errors of the sensors, even if the superheat degree SHout is 0 or more, the refrigerant inside the heater core 12 may contain a portion that dissipates latent heat. That is, even if the superheat degree SHout is 0 or more, the refrigerant inside the heater core 12 may contain a two-phase refrigerant. Therefore, it is difficult to accurately determine whether the refrigerant inside the heater core 12 contains a two-phase refrigerant by determining whether the superheat degree SHout is 0 or more. For this reason, in this embodiment, taking into consideration the detection errors of the sensors, a predetermined value α (α>0) that is estimated to be certain that the refrigerant inside the heater core 12 does not contain a two-phase refrigerant is set as a judgment value of the superheat degree SHout for determining whether the refrigerant inside the heater core 12 contains a two-phase refrigerant. The degree of superheat SHin of the refrigerant flowing into the inlet side 12a of the heater core 12 is also set to a predetermined value α or more, and by determining whether the degree of superheat SHout is a predetermined value α (α>0) or more, it is estimated whether the refrigerant inside the heater core 12 contains two-phase refrigerant. Specifically, if the degree of superheat SHout is the predetermined value α or more, it does not contain two-phase refrigerant, but if the degree of superheat SHout is below the predetermined value α, it is estimated that the refrigerant contains two-phase refrigerant even if it is superheated. Note that the two-phase refrigerant is a refrigerant consisting of a gas refrigerant that is not superheated and a liquid phase refrigerant. The gas refrigerant can also be called a gas phase refrigerant.

[0054] Incidentally, whether or not the refrigerant in the heater core 12 contains a two-phase refrigerant may be estimated by determining whether or not the degree of superheat SHout exceeds 0.

[0055] When the control device 200 determines that the degree of superheat SHout is equal to or greater than the predetermined value α (S2: Yes), it estimates that the refrigerant inside the heater core 12 is all dissipating sensible heat and is only gas refrigerant. In other words, it estimates that the refrigerant inside the heater core 12 does not include two-phase refrigerant. Therefore, the control device 200 estimates that the two-phase refrigerant ratio MO_rate, which is the ratio of the two-phase refrigerant to the refrigerant inside the heater core 12, is 0 (S3).

[0056] Furthermore, when the control device 200 determines that the degree of superheat SHout falls below the predetermined value α (S2: No), it estimates that the refrigerant inside the heater core 12 includes a portion that is dissipating latent heat and includes two-phase refrigerant. Therefore, the control device 200 estimates the two-phase refrigerant ratio MO_rate based on the value of the degree of superheat SHout (S4).

[0057] The control device 200 holds a data table in which the value of the degree of superheat SHout corresponds to the two-phase refrigerant ratio MO_rate. In the data table, when the degree of superheat SHout indicates a lower limit value, the two-phase refrigerant ratio MO_rate indicates a maximum value, that is, a two-phase refrigerant maximum ratio MO_max_rom. As the degree of superheat SHout increases, the two-phase refrigerant ratio MO_rate decreases at a constant rate, and when the degree of superheat SHout indicates a value equal to or greater than a predetermined value α, the two-phase refrigerant ratio MO_rate indicates a minimum value of 0. This is because, as the degree of superheat SHout increases, the ratio of gas refrigerant increases and the ratio of two-phase refrigerant decreases in the heater core 12, and when the degree of superheat SHout becomes equal to or greater than the predetermined value α, the refrigerant in the heater core 12 becomes only gas refrigerant. The control device 200 can estimate the two-phase refrigerant ratio MO_rate by searching the data table based on the value of the degree of superheat SHout.

[0058] Next, the control device 200 estimates the two-phase refrigerant ratio MO_rate, and then calculates the heater core downwind air temperature Thp by the following equation (3) (S5).

[0059] Thp=(1-MO_rate)×Tci+MO_rate×(Tcxin+Tci) / 2···(3) Thp: Air temperature downwind of heater core (℃) MO_rate: Two-phase refrigerant rate Tci: Temperature of the refrigerant flowing out from the heater core outlet (℃) Tcxin: Temperature of the refrigerant flowing into the heater core inlet (℃)

[0060] According to the above formula (3), the part (1-MO_rate)×Tci is the part for calculating the heater core downwind air temperature Thp based on the proportion of gas refrigerant. Also, the part MO_rate×(Tcxin+Tci) / 2 is the part for calculating the heater core downwind air temperature Thp based on the proportion of two-phase refrigerant. Therefore, according to the above formula (3), the heater core downwind air temperature Thp can be calculated according to the proportion of gas refrigerant and the proportion of two-phase refrigerant.

[0061] Therefore, compared to a case where the heater core downwind air temperature Thp is calculated using only one of the calculation formulas corresponding to a gas refrigerant or the calculation formula corresponding to a two-phase refrigerant, the calculation accuracy of the heater core downwind air temperature Thp can be improved by using the above calculation formula (3).

[0062] Then, when the refrigerant in the heater core 12 is only gas refrigerant and the two-phase refrigerant ratio MO_rate=0, the temperature Tci of the refrigerant flowing out from the outlet side 12b of the heater core 12 is estimated as the heater core downwind air temperature Thp. When the ratio of the two-phase refrigerant in the refrigerant in the heater core 12 reaches a maximum and the two-phase refrigerant ratio MO_rate=the maximum two-phase refrigerant ratio MO_max_rom, the heater core downwind air temperature Thp is estimated taking into account the maximum two-phase refrigerant ratio.

[0063] Next, the control device 200 calculates the actual heating capacity Qhp according to the equation (2) above using the heater core downwind side air temperature Thp calculated according to the equation (3) above (S6).

[0064] As described above, by estimating whether the refrigerant inside the heater core 12 is in a state where it is radiating sensible heat and is only gas refrigerant, or whether the refrigerant inside the heater core 12 is in a state where it is radiating latent heat and is two-phase refrigerant, based on the degree of superheat SHout of the outlet side 12b of the heater core 12, it becomes possible to calculate the air temperature on the downwind side of the heater core 12 taking into account the state of the refrigerant inside the heater core 12, and the measurement accuracy of the air temperature on the downwind side of the heater core 12 can be improved without adding an additional sensor for measuring the air temperature on the downwind side of the heater core 12.

[0065] In addition, by estimating the proportion of two-phase refrigerant inside the heater core 12 based on the superheat SHout at the outlet side 12b of the heater core 12, the accuracy of calculating the air temperature on the downwind side of the heater core 12 can be improved without adding a dedicated sensor.

[0066] The present invention is preferably implemented, for example, at the start of the hot gas heating mode. For example, the start of the hot gas heating mode can be divided into three stages.

[0067] In the first stage, the blower 140 does not blow air, and the refrigerant flows through the heater core 12. At this time, the heater core 12 is completely cooled, so the blower 140 does not blow air, but a part of the refrigerant condenses. Therefore, the refrigerant in the heater core 12 includes a gas refrigerant and a two-phase refrigerant. In other words, the refrigerant in the heater core 12 includes a part that dissipates sensible heat and a part that dissipates latent heat. At this time, the degree of superheat SHin at the inlet side 12a of the heater core 12 is equal to or greater than a predetermined value α, but the degree of superheat SHout at the outlet side 12b of the heater core 12 is below the predetermined value α. Therefore, the two-phase refrigerant ratio is estimated based on the degree of superheat SHout, and the heater core leeward air temperature Thp is calculated by the above formula (3).

[0068] In the second stage, although the blower 140 finally starts blowing air, the blower 140 does not blow air for most of the time, and the refrigerant flows through the heater core 12. At this time, the heater core 12 is in a state where it is warmed by the refrigerant, so condensation of the refrigerant does not occur in the heater core 12. Therefore, only gas refrigerant exists as the refrigerant in the heater core 12. In other words, the refrigerant in the heater core 12 is only a portion that dissipates sensible heat. At this time, the superheat degree SHin of the inlet side 12a of the heater core 12 exceeds a predetermined value α, and the superheat degree SHout of the outlet side 12b of the heater core 12 is also equal to or greater than the predetermined value α. Therefore, the two-phase refrigerant ratio is estimated to be 0, and the heater core leeward air temperature Thp is calculated by the above calculation formula (3).

[0069] In the third stage, the blower 140 blows air, and the refrigerant flows through the heater core 12. At this time, a part of the refrigerant is condensed by the blower 140. Therefore, the refrigerant in the heater core 12 includes a gas refrigerant and a two-phase refrigerant. In other words, the refrigerant in the heater core 12 includes a part that dissipates sensible heat and a part that dissipates latent heat. At this time, the degree of superheat SHin at the inlet side 12a of the heater core 12 is equal to or greater than a predetermined value α, but the degree of superheat SHout at the outlet side 12b of the heater core 12 is below the predetermined value α. Therefore, the two-phase refrigerant ratio is estimated based on the degree of superheat SHout, and the heater core leeward air temperature Thp is calculated by the above formula (3).

[0070] In this way, the start of the hot gas heating mode can be distinguished into three stages, and the refrigerant in the heater core 12 contains two-phase refrigerant in the first and third stages, but only gas refrigerant in the second stage. That is, the refrigerant in the heater core 12 transitions between a state in which it contains two-phase refrigerant and a state in which it does not contain two-phase refrigerant. Therefore, in the hot gas heating mode, whether or not the refrigerant contains two-phase refrigerant is estimated based on the superheat SHout of the outlet side 12b of the heater core 12, and the heater core downwind side air temperature Thp is calculated according to the estimated result, thereby improving the accuracy of the calculation of the heater core downwind side air temperature Thp. Accordingly, the accuracy of the calculation of the actual measured value Qhp of the heating capacity can be improved.

[0071] As described above, the control device 200 controls each condition for calculating the heating capacity actual value Qhp so that the heating capacity actual value Qhp achieves the target heating capacity TGQh.

[0072] In other words, when the heater core downwind air temperature Thp becomes high, the air flow rate of the blower 140 is increased to reduce the pressure and temperature of the refrigerant flowing through the heater core 12, and the actual heating capacity value Qhp (kW) is maintained so that the actual heating capacity value Qhp (kW) achieves the target heating capacity TGQh (kW).

[0073] In addition, when the heater core downwind air temperature Thp becomes low, the air flow rate of the blower 140 is reduced to increase the pressure and temperature of the refrigerant flowing through the heater core 12, and the actual heating capacity value Qhp (kW) is maintained so that the actual heating capacity value Qhp (kW) achieves the target heating capacity TGQh (kW).

[0074] However, if the heater core downwind air temperature Thp is calculated with low accuracy, that is, if the actual heating capacity measured value Qhp is calculated with low accuracy, the following problem occurs.

[0075] If the heater core downwind air temperature Thp is calculated to be higher than the actual temperature, the amount of air sent by the blower 140 increases, slowing down the increase in pressure and temperature of the refrigerant flowing through the heater core 12. This increases the time it takes for the actual heating capacity Qhp to reach the target heating capacity TGQh, resulting in a deterioration in the quick heating of the vehicle interior.

[0076] On the other hand, if a heater core downstream air temperature Thp that is lower than the actual temperature is detected, the amount of air sent by the blower 140 is reduced, causing an excessive increase in the pressure of the refrigerant flowing through the heater core 12. This can cause the temperature inside the vehicle cabin to become higher than the target temperature, deteriorating the controllability of the temperature inside the vehicle cabin.

[0077] However, by improving the accuracy of calculating the heater core downwind air temperature Thp, and thereby improving the accuracy of calculating the actual heating capacity value Qhp, it is possible to improve the speed at which the passenger compartment is heated and also improve the controllability of the temperature inside the passenger compartment.

[0078] [Effects of this embodiment] (1) A vehicle air conditioning device 1 including a refrigerant circuit 10 configured to circulate through a compressor 11, a heater core 12 that heats the air supplied to the vehicle cabin, pressure reducing devices 13a to 13e, a low-temperature side heat exchanger 14 that causes the refrigerant to absorb heat from the heat medium absorbed from a battery 41 as an on-board heat generating device, and an accumulator 15, the refrigerant circuit 10 including a bypass path in which the refrigerant that has passed through the compressor 11 bypasses the heater core 12 and flows into the suction side 11b of the compressor 11, and a control device 200 capable of control in a hot gas heating mode in which a portion of the refrigerant that has passed through the compressor 11 flows into the heater core 12 and the remaining refrigerant flows into the bypass path, and the control device 200 calculates the air temperature Thp on the downwind side of the heater core 12 in the hot gas heating mode based on the temperature Tcxin of the refrigerant flowing into the inlet side 12a of the heater core 12, the temperature Tci of the refrigerant flowing out from the outlet side of the heater core 12, and the degree of superheat SHout of the refrigerant flowing out from the outlet side of the heater core 12. Therefore, by estimating based on the degree of superheat SHout of the outlet side 12b of the heater core 12 whether the refrigerant inside the heater core 12 is a gas refrigerant and is in a state where it is radiating sensible heat, or whether the refrigerant inside the heater core 12 is a refrigerant containing two-phase refrigerant and includes a portion where it is radiating latent heat, it becomes possible to calculate the air temperature Thp on the downwind side of the heater core 12 taking into account the state of the refrigerant inside the heater core 12, and the measurement accuracy of the air temperature Thp on the downwind side of the heater core 12 can be improved without adding an additional sensor to measure the air temperature Thp on the downwind side of the heater core 12.

[0079] (2) The control device 200 estimates the proportion of two-phase refrigerant in the refrigerant in the heater core 12 based on the superheat SHout of the refrigerant flowing out from the outlet side 12b of the heater core 12, and calculates the air temperature on the downwind side of the heater core 12 based on the proportion of two-phase refrigerant, the temperature of the refrigerant flowing into the inlet side 12a of the heater core 12, and the temperature of the refrigerant flowing out from the outlet side 12b of the heater core 12. Therefore, by estimating the proportion of two-phase refrigerant inside the heater core 12 based on the superheat SHout at the outlet side 12b of the heater core 12, the accuracy of calculating the air temperature on the downwind side of the heater core 12 can be improved without adding a dedicated sensor.

[0080] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0081] 1: Vehicle air conditioning system 10: refrigerant circuit, 11: compressor, 12: heater core, 13a, 13b, 13c, 13d: pressure reducing device, 14: low-temperature side heat exchanger, 15: accumulator, 16: cooler core, 17: radiator 40: Battery temperature control circuit, 41: Battery, P40: Circulation pump 100: HVAC unit, 110: case, 120: air flow passage, 121: heater core passage, 122: bypass passage, 150: air mix damper

Claims

1. a refrigerant circuit including a compressor, a heater core that heats air to be supplied into a vehicle cabin, a pressure reducing device, a low-temperature side heat exchanger that causes a refrigerant to absorb heat of a heat medium absorbed from an on-board heat generating device, and an accumulator, the refrigerant circulating through the compressor, the refrigerant bypassing the heater core and flowing into a suction side of the compressor; a control device capable of controlling in a hot gas heating mode in which a part of the refrigerant that has passed through the compressor is caused to flow to the heater core and the remaining refrigerant is caused to flow to the bypass path, The control device includes: In the hot gas heating mode, the air temperature on the leeward side of the heater core is calculated based on the temperature of the refrigerant flowing into the inlet side of the heater core, the temperature of the refrigerant flowing out from the outlet side of the heater core, and the degree of superheat of the refrigerant flowing out from the outlet side of the heater core.

1. A vehicle air conditioning system comprising:

2. The control device includes: A ratio of two-phase refrigerant to the refrigerant in the heater core is estimated based on the degree of superheat of the refrigerant flowing out from the outlet side of the heater core, and an air temperature on the leeward side of the heater core is calculated based on the ratio of two-phase refrigerant, the temperature of the refrigerant flowing into the inlet side of the heater core, and the temperature of the refrigerant flowing out from the outlet side of the heater core.

2. The vehicle air conditioning system according to claim 1.

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