On-vehicle air-conditioning system

Abstract

To provide an on-vehicle air-conditioning system capable of reducing noise and electric power consumption.SOLUTION: An on-vehicle air-conditioning system 10 comprises: an air-conditioner 12 which is mounted on a vehicle and has a compressor 20 and a condenser 22; an electric fan 14 which sends air to the condenser 22; a pressure sensor 16 which detects an instantaneous value of pressure of a coolant discharged from the compressor 20 as an instantaneous pressure value Pi; and a controller 18 which controls output of the electric fan 14 according to detected pressure. The controller 18 calculates an average of the instantaneous pressure values Pi over a sampling period, ranging from the current time until a predetermined time as an average pressure value Pave, and drives the electric fan 14 at output larger than a specific standard output Lo when the average pressure value Pave exceeds a specific reference threshold Pth.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present specification discloses an on-board air conditioning system that is installed in a vehicle. [Background technology]

[0002] Conventionally, many vehicle air conditioning systems have been proposed for installation in vehicles. For example, Patent Document 1 discloses an vehicle air conditioning system having a compressor, a condenser, an electric fan, a pressure detection means, and a control means. In Patent Document 1, the detection means detects the pressure of the refrigerant discharged by the compressor. The control means controls the rotation speed of the electric fan according to the detected refrigerant pressure. Specifically, when the detected refrigerant pressure is equal to or greater than a predetermined value, the control means rotates the electric fan at a faster speed than when the detected refrigerant pressure is less than the predetermined value. According to this configuration, when the refrigerant pressure is high, the output of the electric fan is improved, thereby preventing the compressor from being overloaded. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 05-050847 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of the conventional technology such as Patent Document 1, the driving of the electric fan was controlled based on the instantaneous value of the refrigerant pressure, so that the electric fan frequently switched to high-power operation. That is, in order to secure the desired cooling and heating capacity, the rotation speed of the compressor usually increases and decreases in a short time. As the rotation speed of the compressor increases and decreases, the refrigerant pressure also increases and decreases in a short time. As a result, the refrigerant pressure often increases only momentarily. In the case of the conventional air conditioning system, the electric fan was switched to high-power operation even when the refrigerant pressure increased only momentarily. This resulted in an increase in noise and an increase in power consumption.

[0005] Therefore, this specification discloses an in-vehicle air conditioning system that can further reduce noise and power consumption. [Means for solving the problem]

[0006] The vehicle air conditioning system disclosed in this specification is equipped with an air conditioning device mounted on a vehicle and including a compressor and a condenser, an electric fan that blows air to the condenser, a detection device that detects the instantaneous value of the refrigerant pressure discharged by the compressor as an instantaneous pressure value, and a controller that controls the output of the electric fan in accordance with the detected pressure, wherein the controller calculates an average value of the previous instantaneous pressure values ​​during a sampling period from the present to the specified time ago as an average pressure value, and when the average pressure value exceeds a specified reference threshold value, drives the electric fan at a higher output than a specified standard output. Effect of the Invention

[0007] According to the vehicle air conditioning system disclosed in this specification, the output of the electric fan is switched based on the average pressure value, so the frequency of switching to high-output operation can be kept low, resulting in further reductions in noise and power consumption. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram showing the configuration of an air conditioning system. [Diagram 2] 2 is a graph showing the variation over time of several parameters related to an air conditioning system; [Diagram 3] 1 is a graph showing the variation over time of several parameters associated with a conventional air conditioning system; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The configuration of the air conditioning system 10 will be described below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of the air conditioning system 10. The air conditioning system 10 is mounted on a vehicle. The air conditioning system 10 includes an air conditioner 12, an electric fan 14, a pressure sensor 16, and a controller 18.

[0010] The air conditioner 12 conditions the interior of the vehicle in response to a request from a user. The air conditioner 12 includes a heat pump circuit that transfers heat by combining expansion and contraction of a refrigerant and heat exchange between the refrigerant and the outside. More specifically, the air conditioner 12 includes a compressor 20, a condenser 22, an evaporator 24, a blower fan 26, and a refrigerant flow path 28. The compressor 20 compresses and discharges the refrigerant flowing through the refrigerant flow path 28. The compression pressure, and therefore the rotation speed of the compressor 20, are increased or decreased according to the required cooling or heating capacity. A controller 18, which will be described later, feedback controls the rotation speed of the compressor 20 so as to maintain the required cooling or heating capacity, for example.

[0011] The pressure of the refrigerant discharged from the compressor 20 is detected by the pressure sensor 16. The pressure sensor 16 detects the refrigerant pressure at each predetermined detection period and outputs the detected pressure to the controller 18. The refrigerant pressure is an index representing the load on the compressor 20. The value of the refrigerant pressure detected by the pressure sensor 16 is the instantaneous pressure value at the detection timing. Therefore, hereinafter, the refrigerant pressure detected by the pressure sensor 16 is referred to as the "instantaneous pressure value Pi."

[0012] Condenser 22 is a heat exchanger that exchanges heat between the refrigerant discharged from compressor 20 and outside air. Condenser 22 is disposed, for example, at the front of the vehicle so as to receive wind generated while the vehicle is running. In addition, electric fan 14 is disposed behind condenser 22. Electric fan 14 draws in wind behind condenser 22 and sends the wind to the front of condenser 22. The rotation speed of electric fan 14 is controlled by controller 18 according to the load on compressor 20, and thus the refrigerant pressure, which will be described later.

[0013] During cooling operation, the refrigerant is depressurized and expanded by an expansion valve (not shown) and then supplied to the evaporator 24. The depressurized and expanded refrigerant evaporates in the evaporator 24. During this evaporation process, the air around the evaporator 24 is cooled. The blower fan 26 blows the cooled air into the vehicle cabin. Although not shown in FIG. 1, the air conditioner 12 further includes a heater core that heats the refrigerant. During heating operation, the refrigerant is sent to the heater core without passing through the evaporator 24 and is heated. The blower fan 26 blows the air around the heater core into the vehicle cabin. The heat source for the heater core can be, for example, exhaust heat from the engine.

[0014] 1 is an example, and other configurations may be changed as long as the air conditioner 12 has the compressor 20 and the condenser 22. For example, the air conditioner 12 may further have a second refrigerant circuit through which a refrigerant other than the air conditioning refrigerant flows in order to adjust the temperature of a battery or the like mounted on the vehicle. In this case, the air conditioner 12 may further have a chiller that exchanges heat between the second refrigerant circuit and the air conditioning refrigerant.

[0015] The controller 18 controls the operation of the compressor 20 and the blower fan 26 in accordance with the required heating / cooling capacity, and also controls the operation of the electric fan 14 based on the detection value of the pressure sensor 16. The controller 18 is physically a computer having a processor and a memory.

[0016] The drive control of the compressor 20 and the blower fan 26 by the controller 18 can be performed using known techniques, and therefore detailed description thereof will be omitted here. The controller 18 further controls the drive of the electric fan 14 based on the refrigerant pressure detected by the pressure sensor 16. The drive control of the electric fan 14 will be described below.

[0017] When the refrigerant pressure is high, it can be said that the load on the compressor 20 is high. If left in this state, the load on the compressor 20 will become excessive, leading to increased power consumption and breakdown of the compressor 20. For this reason, conventionally, when the pressure of the refrigerant discharged from the compressor 20 is high, the output of the electric fan 14 is increased to improve the heat exchange efficiency in the condenser 22.

[0018] However, conventionally, the controller 18 determines whether or not the output of the electric fan 14 needs to be changed based on a comparison between the instantaneous pressure value Pi detected by the pressure sensor 16 and a reference threshold value Pth. In this case, there is a risk that the electric fan 14 will be frequently switched to high output operation. This will be described with reference to FIG.

[0019] Fig. 3 is a graph showing the change over time of each parameter in a conventional air conditioning system. In Fig. 3, the first line shows the rotation speed of the compressor 20, the second line shows the heating and cooling capacity of the air conditioner 12, the third line shows the refrigerant pressure, and the fourth line shows the change in output of the electric fan 14.

[0020] As described above, the controller 18 feedback controls the rotation speed of the compressor 20 based on the output from the air conditioner 12 (i.e., the refrigerant capacity). Therefore, when the refrigerant capacity is below the target value, the controller 18 increases the rotation speed of the compressor 20, and when the refrigerant capacity is above the target value, the controller 18 decreases the rotation speed of the compressor 20. As a result, the rotation speed of the compressor 20 repeatedly increases and decreases within a short period of time, as shown in the first row of Fig. 3.

[0021] As the rotation speed of the compressor 20 increases and decreases, the instantaneous pressure value Pi detected by the pressure sensor 16 also repeatedly increases and decreases within a short period of time, as shown in the third row of Fig. 3. In conventional air conditioning systems, the controller 18 compares this instantaneous pressure value Pi with a predefined reference threshold value Pth, and when Pi>Pth, switches the output of the electric fan 14 from standard output Lo to high output Hi. As a result, in the example of Fig. 3, there are multiple periods during which the electric fan 14 is operated at high output Hi, even if only for a short period of time.

[0022] Naturally, operating the electric fan 14 at high power Hi results in increased power consumption and increased noise. Of course, if the load on the compressor 20 is continuously high, it is necessary to operate the electric fan 14 at high power Hi, even if this increases power consumption. However, as shown in Figure 3, in a situation where the high load state of the compressor 20 occurs only for a short period of time, there is little need to operate the electric fan 14 at high power Hi.

[0023] Therefore, in this example, the need to switch the output of the electric fan 14 is determined based not on the instantaneous pressure value Pi but on the average value of the instantaneous pressure values ​​Pi obtained within a period from the present to a predetermined time ago (hereinafter referred to as the "average pressure value Pave"). This will be described with reference to Fig. 2. Fig. 2 is a graph showing the changes over time of each parameter in the air-conditioning system 10 disclosed in this specification. In the third graph in Fig. 2, the solid line indicates the average pressure value Pave, and the dashed dotted line indicates the instantaneous pressure value Pi.

[0024] The behavior of the rotation speed (first stage) and the heating / cooling capacity (second stage) of the compressor 20 shown in Fig. 2 is the same as that in Fig. 3, and therefore a description thereof will be omitted. In this example, as described above, the necessity of switching the output of the electric fan 14 is determined based on the average pressure value Pave.

[0025] As described above, the pressure average value Pave is the average value of the pressure instantaneous values ​​Pi obtained during a period from the present to a predetermined period ago (hereinafter referred to as the "sampling period"). In other words, the pressure average value Pave is a moving average value of the pressure instantaneous values ​​Pi. The length of the sampling period when calculating the pressure average value Pave is not particularly limited. For example, when the fluctuation period Ts of the compressor rotation speed is determined to a certain extent, the sampling period may be longer than the fluctuation period Ts.

[0026] 2, the pressure average value Pave has a smaller fluctuation amplitude than the pressure instantaneous value Pi. As a result, even if the pressure instantaneous value Pi momentarily exceeds the reference threshold value Pth, the pressure average value Pave is less likely to exceed the reference threshold value Pth.

[0027] The controller 18 compares this average pressure value Pave with the reference threshold value Pth. If Pave>Pth, the controller 18 sets the output of the electric fan 14 to high output Hi. In the example of Fig. 2, the instantaneous pressure value Pi exceeds the reference threshold value Pth, but the average pressure value Pave does not exceed the reference threshold value Pth. Therefore, the controller 18 does not switch the output of the electric fan 14 to high output Hi, but keeps it at standard output Lo.

[0028] In this way, by determining whether to switch the output of the electric fan 14 based on the average pressure value Pave, it is possible to effectively prevent the output from being switched to high output Hi in the short term, thereby preventing an increase in power consumption and noise.

[0029] In this example, the reference threshold value Pth is a single value, but the reference threshold value Pth may have a certain range. For example, a first reference threshold value Pth1 and a second reference threshold value Pth2 higher than the first reference threshold value Pth1 may be set. In this case, when the pressure average value Pave exceeds the second reference threshold value Pth2 in the increasing process, the output may be switched from the standard output Lo to the high output Hi, and when the pressure average value Pave falls below the first reference threshold value Pth1 in the decreasing process, the output may be switched from the high output Hi to the standard output Lo. With this configuration, the frequency of switching the output of the electric fan 14 can be further reduced.

[0030] In the above description, the output of the electric fan 14 is switched in two stages, but it may be switched in more stages. For example, when the pressure average value Pave is equal to or less than the first reference threshold value Pth1, the standard output Lo may be adopted, when the pressure average value Pave exceeds the first reference threshold value Pth1 and is less than the second reference threshold value Pth2, the medium output Md may be adopted, and when the pressure average value Pave exceeds the second reference threshold value Pth2, the high output Hi may be adopted. In this case, the medium output Md may be Lo, <Md<Hiである。 [Explanation of symbols]

[0031] 10 air conditioning system, 12 air conditioning unit, 14 electric fan, 16 pressure sensor, 18 controller, 20 compressor, 22 condenser, 24 evaporator, 26 blower fan, 28 refrigerant flow path.

Claims

[Claim 1] an air conditioning device mounted on a vehicle and including a compressor and a condenser; An electric fan for blowing air into the condenser; a detection device that detects an instantaneous value of the pressure of the refrigerant discharged from the compressor as an instantaneous pressure value; a controller for controlling the output of the electric fan in response to the detected pressure; the controller calculates an average value of the instantaneous pressure values ​​during a sampling period from the present time until the predetermined time ago as an average pressure value, and drives the electric fan at a higher output than a specified standard output when the average pressure value exceeds a specified reference threshold value. The vehicle air conditioning system is characterized by the above.

Images