Vehicle air conditioner

Abstract

To provide a vehicle air conditioner which can inhibit erroneous judgment of frost formation to achieve high performance.SOLUTION: A vehicle air conditioner includes: an outdoor heat exchanger 11 which exchanges heat with outside air; a compressor 13 which compresses a refrigerant; an outside air temperature sensor 21 configured to detect an outside air temperature Ta; a refrigerant temperature sensor 22 configured to detect a refrigerant outlet temperature Tr which is an outlet temperature of the refrigerant in the outdoor heat exchanger 11; and a determination part 23 which determines whether or not frost is formed on the outdoor heat exchanger 11 based on a temperature difference ΔT between the detected outside air temperature Ta and the refrigerant outlet temperature Tr. The determination part 23 adds a correction value C set according to a rotation number R of the compressor 13 to the temperature difference ΔT to determine whether or not frost is formed.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses an in-vehicle air conditioning system that determines that frost has occurred on an outdoor heat exchanger based on the elapsed time during which the temperature difference between the refrigerant in the refrigerant flow path on the outlet side of the outdoor heat exchanger and the outside air is equal to or greater than the frost temperature difference at which frost may occur on the outdoor heat exchanger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-41521 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the refrigerant temperature at the outlet side of the outdoor heat exchanger also depends on the compressor rotation speed, in the vehicle air conditioning system described in Patent Document 1 above, a momentary increase in the compressor rotation speed may be mistakenly determined as frost formation, which may result in a reduction in heating capacity.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a vehicle air conditioner that can suppress erroneous determination of frost formation and exhibit high performance. [Means for solving the problem]

[0006] In order to achieve the above object, the vehicle air conditioning device of the present invention comprises: an outdoor heat exchanger that exchanges heat with outdoor air; A compressor that compresses a refrigerant; An outside air temperature sensor for detecting an outside air temperature; a refrigerant temperature sensor for detecting a refrigerant outlet temperature, which is an outlet temperature of the refrigerant in the outdoor heat exchanger; a determination unit that determines whether or not frost has formed on the outdoor heat exchanger based on a temperature difference between the detected outside air temperature and the detected refrigerant outlet temperature; Equipped with The determination unit determines the presence or absence of frost by adding a correction value corresponding to a rotation speed of the compressor to the temperature difference.

[0007] With a vehicle air conditioning system having this configuration, a correction value according to the compressor rotation speed is added to the temperature difference between the outside air temperature and the refrigerant outlet temperature, which is used to determine whether frost has formed, thereby preventing erroneous determination of frost formation due to momentary increases in the compressor rotation speed and suppressing a decrease in heating capacity. Effect of the Invention

[0008] According to the present invention, it is possible to provide a vehicle air conditioner that can suppress erroneous determination of frost formation and exhibit high performance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a vehicle air conditioner according to this embodiment. [Diagram 2] FIG. 2 is a graph for explaining a general determination of frost formation. [Diagram 3] FIG. 3 is a graph illustrating the determination of frost formation according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram of a vehicle air conditioner 10 according to this embodiment.

[0011] 1, a vehicle air conditioner 10 according to this embodiment includes, as an example, an exterior heat exchanger 11, an evaporator 12, a compressor 13, and an expansion valve 14. The exterior heat exchanger 11 and the evaporator 12 are connected by a pipe 15, and a refrigerant is circulated through the pipe 15. The compressor 13 is provided in one of the pipes 15, and the expansion valve 14 is provided in the other pipe 15.

[0012] The exterior heat exchanger 11 is a condenser disposed outside the vehicle, and the refrigerant exchanges heat with outside air by this exterior heat exchanger 11. The exterior heat exchanger 11 is equipped with a fan 11a, and the efficiency of heat exchange in the exterior heat exchanger 11 is increased by blowing outside air by this fan 11a. The evaporator 12 is disposed inside the vehicle, and the refrigerant exchanges heat with the air in the room by this evaporator 12. The evaporator 12 is equipped with a blower 12a, and the air that has been heat exchanged by the evaporator 12 is sent into the room by the blower 12a.

[0013] During cooling operation, in the vehicle air conditioner 10, the refrigerant compressed and liquefied by the compressor 13 is cooled by heat exchange with the outside air in the exterior heat exchanger 11. The refrigerant cooled in the exterior heat exchanger 11 is expanded and vaporized in the expansion valve 14 and sent to the evaporator 12. In this way, in the evaporator 12, the air in the vehicle is cooled by the latent heat generated when the refrigerant vaporizes, and cool air is sent into the vehicle by the blower 12a.

[0014] During heating operation, in the vehicle air conditioner 10, the refrigerant expanded by the expansion valve 14 to a low temperature is heated by heat exchange in the exterior heat exchanger 11. The refrigerant that has passed through the exterior heat exchanger 11 is compressed and liquefied by the compressor 13 to a high temperature, and is sent to the evaporator 12. As a result, the air is heated by the evaporator 12, and the air is sent into the vehicle interior as hot air by the blower 12a.

[0015] The vehicle air conditioner 10 having the above-mentioned configuration includes an outside air temperature sensor 21, a refrigerant temperature sensor 22, and a determination unit .

[0016] The outside air temperature sensor 21 detects the outside air temperature Ta and is disposed outside the vehicle. The refrigerant temperature sensor 22 detects the refrigerant outlet temperature Tr, which is the outlet temperature of the refrigerant in the exterior heat exchanger 11.

[0017] The determination unit 23 determines whether or not frost has formed in the exterior heat exchanger 11 of the vehicle air conditioner 10. The determination unit 23 is connected to an outside air temperature sensor 21, and a detection signal of an outside air temperature Ta is transmitted from the outside air temperature sensor 21. The determination unit 23 is also connected to a refrigerant temperature sensor 22, and a detection signal of a refrigerant outlet temperature Tr is transmitted from the refrigerant temperature sensor 22. The determination unit 23 is also connected to a compressor 13, and data of the rotation speed R of the compressor 13 is transmitted.

[0018] The judgment unit 23 judges whether or not frost has formed during heating operation based on the detection signals of the outside air temperature Ta, the detection signal of the refrigerant outlet temperature Tr, and the rotation speed R of the compressor 13 transmitted from the outside air temperature sensor 21, the refrigerant temperature sensor 22, and the compressor 13.

[0019] Incidentally, frost formation during heating operation occurs due to an increase in the temperature difference ΔT (ΔT=Ta-Tr) between the outside air temperature Ta and the refrigerant outlet temperature Tr. In other words, it is considered that frost formation is progressing as the temperature difference ΔT increases. Therefore, the temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr can be monitored to determine whether frost formation has occurred.

[0020] FIG. 2 is a graph illustrating a typical determination of frost formation based on a temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr.

[0021] In a typical determination of the presence or absence of frost based on the outside air temperature Ta and the refrigerant outlet temperature Tr, it is determined that frost has formed when the temperature difference ΔT between the outside air temperature Ta obtained from the outside air temperature sensor 22 and the refrigerant outlet temperature Tr obtained from the refrigerant temperature sensor 22 exceeds a preset threshold value Th (see the graph of ΔT in Figure 2).

[0022] Incidentally, the temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr varies depending on the operating state of the compressor 13 (see the graph of the compressor rotation speed R in FIG. 2). Specifically, the refrigerant outlet temperature Tr also varies with the variation in the rotation speed R of the compressor 13, and the temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr also varies in a similar manner. For this reason, when the rotation speed R of the compressor 13 increases and the refrigerant outlet temperature Tr decreases, and the temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr temporarily increases and exceeds the threshold value Th (at the time of timing t in FIG. 2), it may be erroneously determined that frost has formed on the outdoor heat exchanger 11, even though frost has not actually formed.

[0023] After the occurrence of frost is erroneously determined, the rotation speed R of the compressor 13 is reduced in order to suppress the progress of frost (see the graph of the compressor rotation speed R in FIG. 2). As a result, by reducing the rotation speed R of the compressor 13, the heating capacity after the timing t at which the occurrence of frost is determined is reduced (see the graph of the heating capacity in FIG. 2). Note that, with the reduction in the rotation speed R of the compressor 13, the frost ratio after the timing t at which the occurrence of frost is determined is reduced more than necessary (see the graph of the frost ratio in FIG. 2).

[0024] In order to avoid such an erroneous determination of frost formation, in the present invention, the determination unit 23 performs the determination as follows. FIG. 3 is a graph illustrating the determination of frost formation according to the present invention.

[0025] First, a temperature difference ΔT between the outside air temperature Ta acquired from the outside air temperature sensor 22 and the refrigerant outlet temperature Tr acquired from the refrigerant temperature sensor 22 is calculated.

[0026] Furthermore, a correction value C for correcting this temperature difference ΔT is obtained. This correction value C is derived from the rotation speed R of the compressor 13, and is calculated by the following formula (1) in which A is a fixed constant.

[0027] C = A × R … (1)

[0028] Then, the correction value C is added to the temperature difference ΔT to obtain a judgment value ΔT+C, and this judgment value ΔT+C is compared with a preset threshold value Th (see the graph of ΔT+C in FIG. 3). When this sum ΔT+C exceeds the preset threshold value Th, it is determined that frost has formed on the outdoor heat exchanger 11.

[0029] In this way, by determining whether frost has formed by taking into account the correction value C derived from the rotation speed R of the compressor 13, even if the rotation speed R of the compressor 13 fluctuates (see the graph of the compressor rotation speed R in FIG. 3), fluctuations in the judgment value ΔT+C for determining whether frost has formed can be suppressed (see the graph of ΔT+C in FIG. 3).

[0030] Therefore, erroneous determination of frost formation due to a momentary increase in the rotation speed R of the compressor 13 is suppressed, and a decrease in the heating capacity can be suppressed (see the graph of heating capacity in FIG. 3). In this case, since the heating capacity is maintained, the frost ratio gradually increases until the determination value ΔT+C exceeds the threshold value Th (see the graph of frost ratio in FIG. 3).

[0031] As described above, according to the vehicle air conditioning device 10 of this embodiment, by adding a correction value C corresponding to the rotation speed R of the compressor 13 to the temperature difference ΔT between the outside air temperature Ta and the refrigerant outlet temperature Tr, which are used to determine the presence or absence of frost, it is possible to suppress erroneous determination of frost due to a momentary increase in the rotation speed R of the compressor 13 and suppress a decrease in heating capacity. [Explanation of symbols]

[0032] 10. Air conditioning system for vehicles 11 Outdoor heat exchanger 13 Compressor 21 Outside air temperature sensor 22 Refrigerant temperature sensor 23 Judgment section C Correction Value R Rotational Speed Ta Outside temperature Tr Refrigerant outlet temperature ΔT temperature difference

Claims

[Claim 1] an outdoor heat exchanger that exchanges heat with outdoor air; A compressor that compresses a refrigerant; An outside air temperature sensor for detecting an outside air temperature; a refrigerant temperature sensor for detecting a refrigerant outlet temperature, which is an outlet temperature of the refrigerant in the outdoor heat exchanger; a determination unit that determines whether or not frost has formed on the outdoor heat exchanger based on a temperature difference between the detected outside air temperature and the detected refrigerant outlet temperature; Equipped with The determination unit determines whether or not frost has formed by adding a correction value corresponding to the rotation speed of the compressor to the temperature difference. Vehicle air conditioning system.

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