Vehicle air conditioner

Abstract

To realize a vehicle air conditioner which prevents the generation of coolant flow noise.SOLUTION: A vehicle air conditioner comprises: a control section 12 which controls air-conditioning in a vehicle; an evaporator 14; a compressor 16; a condenser 18; coolant piping 20 which serves as a flow passage for circulating coolant and connects the evaporator 14, the compressor 16, and the condenser 18; and an expansion valve 22 which is installed on a passage constituting the coolant piping 20 and connecting the condenser 18 and the evaporator 14. The control section 12 operates so as to concentrate air conditioning on a specific vehicle seat and to increase the number of air outlets that discharge conditioned air into the vehicle interior when an air-conditioning load is equal to or below a predetermined value.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] A vehicle is provided with an air conditioner that controls the environment inside the vehicle, such as the temperature inside the vehicle. Conventionally, various technologies related to the air conditioner have been proposed to meet various objectives, such as improving fuel efficiency and improving comfort inside the vehicle.

[0003] For example, the vehicle air conditioning system disclosed in Patent Document 1 is said to be able to reduce the load on the air conditioning system by controlling the air conditioning depending on the presence or absence of occupants other than the driver's seat, or to provide effective air conditioning for both occupants in the driver's seat and those in other seats when their temperature sensations differ.

[0004] Patent Document 2 discloses a vehicle air conditioner that aims to suppress the generation of noise. This vehicle air conditioner is said to be able to suppress the generation of refrigerant passing sounds in the refrigeration cycle device and compressor suction pulsation sounds by acquiring the load amount of the refrigeration cycle device and switching the control method of the compressor based on this load amount. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-47454 A [Patent Document 2] Patent Publication No. 2021-079827 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the load on the air conditioner is reduced, the refrigerant passing noise, which is the noise made by the refrigerant circulating inside the air conditioner, increases, and this can cause a loss of comfort in the vehicle cabin. This is thought to be because the evaporation of the refrigerant in the evaporator becomes insufficient when the load on the air conditioner is reduced.

[0007] Therefore, this specification provides a vehicle air conditioning device that suppresses the generation of refrigerant passing noise. [Means for solving the problem]

[0008] The vehicle air conditioning system disclosed in this specification comprises a control unit that controls the vehicle air conditioning, an evaporator, a compressor, a condenser, a refrigerant piping that is a flow path through which a refrigerant circulates and that connects the evaporator, the compressor, and the condenser, and an expansion valve that is provided on a path in the refrigerant piping that connects the condenser and the evaporator, and is characterized in that the control unit operates to concentrate the air conditioning on one seat in the vehicle cabin, and when the air conditioning load is below a predetermined value, controls to increase the number of air outlets for the conditioned air blown into the vehicle cabin. Effect of the Invention

[0009] According to the vehicle air conditioning system disclosed in this specification, the load on the air conditioning system is increased by increasing the number of outlets for the conditioned air to be blown into the vehicle cabin under certain conditions, which results in suppressing the generation of refrigerant passing noise that is likely to occur when the load on the air conditioning system is low. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of an air conditioning system for a vehicle; [Diagram 2] 4 is a graph showing the state of the refrigerant when the vehicle air conditioning device is under low load. [Diagram 3] 4 is a flowchart showing an example of a process in an air conditioning device of a vehicle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an air conditioner for a vehicle will be described with reference to the drawings.

[0012] FIG. 1 is a schematic diagram of an air conditioner for a vehicle. More specifically, FIG. 1 is a perspective view of the front of a vehicle, which is a schematic diagram of an example of the configuration of an air conditioner 10 for a vehicle disclosed in this specification. As shown in FIG. 1, the air conditioner 10 for a vehicle includes a control unit 12, an evaporator 14, a compressor 16, a condenser 18, a refrigerant pipe 20, and an expansion valve 22. Here, in this example, in the air conditioner 10 for a vehicle, sensors detect the presence or absence of occupants in each seat, such as the driver's seat and the passenger seat, the front seats and the rear seats, and control the air conditioning in the vehicle cabin. This airflow control technology is called S-Flow (Save energy + airflow control).

[0013] The control unit 12 is an electronic control unit having at least a CPU that performs various arithmetic processing, and a memory in which control programs and data are stored. For example, the control unit 12 controls the air conditioner 10, and controls the temperature of the conditioned air that is blown from the air conditioner 10 into the vehicle cabin, and the position of the air outlet for the conditioned air. The control unit 12 also controls the operation of each part of the air conditioner 10. In Fig. 1, each part that is the target of control by the control unit 12 is shown surrounded by a two-dot chain line.

[0014] The evaporator 14 is a device that changes the state of the refrigerant circulating inside the air conditioner 10 from a liquid state (hereinafter referred to as a "liquid-phase refrigerant") to a gas state (hereinafter referred to as a "gas-phase refrigerant"). In other words, the evaporator 14 is a heat exchanger that evaporates the refrigerant circulating inside the air conditioner 10 and removes heat from the surroundings.

[0015] The compressor 16 is a device connected to the evaporator 14 via a refrigerant pipe 20. The compressor 16 draws in low-pressure, low-temperature gas after evaporation in the evaporator 14, compresses it, and discharges it at high pressure and high temperature. The discharged gas-phase refrigerant is then sent to the condenser 18.

[0016] The condenser 18 is a device connected to the compressor 16 via a refrigerant pipe 20. The condenser 18 is a heat exchanger that is installed at the front of the vehicle and exchanges heat with the air outside the vehicle. The gas-phase refrigerant discharged from the compressor 16 is condensed and liquefied when passing through the condenser 18. More specifically, when the air conditioner 10 performs cooling operation, the condenser 18 condenses the gas-phase refrigerant into a liquid-phase refrigerant by releasing heat to the outside to reduce the energy of the refrigerant.

[0017] As shown in FIG. 1, the refrigerant piping 20 connects the evaporator 14, the compressor 16, the condenser 18, and an expansion valve 22, and is a piping through which a refrigerant circulates.

[0018] The expansion valve 22 is disposed on the passage of the refrigerant pipe 20 at a portion connecting the condenser 18 and the evaporator 14. More specifically, the expansion valve 22 is a pressure reducing device that reduces the pressure of the high-pressure refrigerant liquefied in the condenser 18 when the refrigerant is passed through the expansion valve 22. The pressure reduction in the expansion valve 22 is achieved by expanding the liquid phase refrigerant in one go and spraying it in a mist form from high pressure to low pressure. At this time, thermal energy is taken away by expanding the refrigerant in one go from high pressure to low pressure, and the boiling point of the refrigerant is lowered. In other words, the temperature of the refrigerant after passing through the expansion valve 22 drops sharply.

[0019] The refrigerant after passing through the expansion valve 22 is a low-pressure, low-temperature mist (in other words, a gas-liquid two-phase refrigerant). The gas-liquid two-phase refrigerant flows into the evaporator 14 and exchanges heat with the air in the vehicle cabin, causing the refrigerant circulating in the air conditioner 10 to evaporate, and the air in the vehicle cabin is cooled.

[0020] Next, the state of the refrigerant circulating inside an air conditioner 10 that employs S-Flow technology and the effect that state has on the vehicle's quietness will be described with reference to Fig. 2. Fig. 2 is a graph showing the state of the refrigerant when the vehicle's air conditioner is under low load. Here, "the air conditioner 10 is under low load" refers to a state in which S-Flow controls the air conditioning according to the number and positions of the vehicle's passengers, eliminating excessive operation of the air conditioner, resulting in a lower load on the air conditioner 10 and a smaller flow rate of the circulating refrigerant.

[0021] The graph in Fig. 2 shows the refrigeration cycle of the air conditioner when the air conditioner 10 is under low load, based on the known Mollier diagram, which shows the refrigeration cycle of the air conditioner in which the refrigerant changes pressure and temperature as well as the gas-liquid transition. In the mountain-shaped curve shown in the center of the graph in Fig. 2, the left solid line is the saturated liquid line, and the right dashed line is the saturated vapor line. As shown in Fig. 2, in the region to the left of the saturated liquid line, the refrigerant exists as a liquid, and in the region to the right of the saturated vapor line, the refrigerant exists as a gas. In the central region surrounded by the saturated liquid line and the saturated vapor line, the refrigerant exists in a two-phase gas-liquid state.

[0022] As shown in FIG. 2, when the air conditioner 10 is in a low-load state, the line connecting the condenser 18 and the expansion valve 22 is mostly included in the central region surrounded by the saturated liquid line and the saturated vapor line. This indicates that the refrigerant discharged from the condenser 18 exists in a gas-liquid two-phase state. Here, the graph surrounded by the two-dot chain line at the bottom of FIG. 2 is a graph for comparison, and is a Mollier diagram showing the refrigeration cycle of the air conditioner 10 when the air conditioner 10 is in a normal state (i.e., a state other than a low-load state). In the graph of the normal state surrounded by the two-dot chain line shown at the bottom, the line connecting the condenser 18 and the expansion valve 22 is located in the region to the left of the saturated liquid line. This indicates that the refrigerant discharged from the condenser 18 exists in a liquid state. That is, as is clear from the two graphs shown in FIG. 2, the state of the refrigerant after passing through the condenser 18 differs depending on whether the air conditioner 10 is in a low-load state or a normal state. The difference in the state of the refrigerant is also indicated in FIG. 2 by the length of the double-headed arrow SC. The double-headed arrow SC indicates the subcooling, which is the difference between the saturation temperature of the refrigerant in the condenser 18 and the actual temperature of the refrigerant from the condenser 18. In other words, the subcooling indicates how many degrees the refrigerant has dropped from the saturation temperature. As shown in FIG. 2, when the air conditioner 10 is in a low-load state, the subcooling, which indicates the amount of further cooling from the saturated liquid line, is not achieved (in FIG. 2, this is represented by the short length of the subcooling arrow represented by the double-headed arrow SC). In such a case, the refrigerant is not sufficiently cooled by the condenser 18. As a result, while it is originally desirable for the refrigerant after passing through the condenser 18 to be condensed into a liquid-phase refrigerant, when the air conditioner 10 is in a low-load state, gas refrigerant remains and the refrigerant is in a gas-liquid two-phase state. On the other hand, in the graph for comparison surrounded by the two-dot chain line at the bottom of FIG. 2, the subcooling is achieved (in FIG. 2, this is represented by the long length of the subcooling arrow represented by the double-headed arrow SC). That is, when the air conditioner 10 is in a normal state (that is, a state other than a low load state), the refrigerant that has passed through the condenser 18 is sufficiently cooled by the condenser 18 and is condensed into a liquid-phase refrigerant.

[0023] The above will be further explained, including the function of each part constituting the air conditioner 10 of the vehicle. First, since the S-Flow control is working in the air conditioner 10, the load of the air conditioner 10 is low, and the amount of refrigerant circulating in the air conditioner 10 is likely to be small. When the amount of refrigerant circulating is small, the evaporator 14, which functions as a heat exchanger, receives less heat than usual from the inside of the vehicle cabin. That is, when the refrigerant passes through the evaporator 14, it cannot evaporate completely, and the refrigerant flowing from the evaporator 14 to the compressor 16 becomes a two-phase gas-liquid refrigerant. Originally, the compressor 16 sucks in low-pressure and low-temperature gas after evaporation in the evaporator 14. However, as described above, when the two-phase gas-liquid refrigerant flows in instead of gas, liquid pools are generated at the intake port of the compressor 16. Then, the liquid pools reduce the capacity of the compressor 16. As a result, the amount of refrigerant discharged from the compressor 16 becomes smaller than usual.

[0024] As described above, when the amount of refrigerant discharged from the compressor 16 becomes smaller than the amount of refrigerant passing through the expansion valve 22, a part of the gas-phase refrigerant is easily passed through the condenser 18, and the refrigerant flows into the expansion valve 22 without being sufficiently cooled by the condenser 18 (i.e., in a gas-liquid two-phase state). At this time, bubbles are easily generated between the condenser 18 and the expansion valve 22, and as a result, two-phase refrigerant with bubbles flows into the expansion valve 22. Here, when the two-phase refrigerant with bubbles passes through the expansion valve 22, vibrations are generated. Then, the vibrations are transmitted to the evaporator 14 on the passenger compartment side through the refrigerant piping 20, and the sound is transmitted to the outlet of the air-conditioned air blown into the passenger compartment. As described above, in the air conditioner 10 employing the S-Flow technology, the load on the air conditioner 10 is reduced, and the state of the refrigerant circulating in the air conditioner 10 changes from the normal state, which results in an increase in the refrigerant passing sound, which may adversely affect the quietness of the vehicle.

[0025] Therefore, in the vehicle air conditioner disclosed in this specification, taking into consideration the above characteristics, in order to suppress the generation of refrigerant passing noise, even the air conditioner 10 that employs S-Flow technology is controlled to increase the air conditioning load by increasing the number of outlets for the conditioned air blown into the vehicle cabin under certain conditions. This control will be specifically described with reference to FIG.

[0026] 3 is a flowchart showing an example of processing in a vehicle air conditioner. The control unit 12 judges whether the air conditioning is automatically concentrated in one seat by S-Flow (S10). If the air conditioning is automatically concentrated in one seat (Yes in S10), the processing proceeds to step S12. On the other hand, if the air conditioning is not automatically concentrated in one seat (No in S10), the processing proceeds to step S20. Here, if there is no passenger in any seat other than the driver's seat and the air conditioning is only operating in the driver's seat (for example, the conditioned air blown into the vehicle cabin is only blown out from the outlet on the driver's seat side), the load on the air conditioner 10 is low.

[0027] Next, the control unit 12 judges whether the outside air temperature is 8°C or higher (S12). If the outside air temperature is 8°C or higher (Yes in S12), the process proceeds to step S14. On the other hand, if the outside air temperature is less than 8°C (No in S12), the process proceeds to step S30. In general, when the outside air temperature is high, the load of the cooling function of the air conditioner increases. On the other hand, when the outside air temperature is less than 8°C, the load of the air conditioner 10 increases in order to maintain the dehumidification function. In other words, when the outside air temperature is between 8°C and 30°C, the load on the air conditioner 10 decreases. Therefore, in S12 of this example, 8°C is used as the judgment criterion, and cases where the load of the dehumidification function increases are excluded.

[0028] Next, the control unit 12 determines whether the vehicle is stopped (S14). If the vehicle is stopped (Yes in S14), the process proceeds to step S16, and if the vehicle is not stopped (No in S14), the process proceeds to step S30. Here, when the vehicle is stopped, the background noise is quiet, so the refrigerant passing sound can be clearer.

[0029] Next, the control unit 12 judges whether the target temperature after passing through the evaporator 14 is 5°C or more (S16). If the target temperature after passing through the evaporator 14 is 5°C or more (Yes in S16), the process proceeds to step S18, and if it is less than 5°C (No in S16), the process proceeds to step S30. The expansion valve 22 has a function of controlling the flow rate of the refrigerant in addition to the function as a pressure reducing device, and generally controls the flow rate of the refrigerant so that the target temperature after passing through the evaporator 14 is maintained at 5°C to 10°C. That is, if the target temperature after passing through the evaporator 14 is less than 5°C, the load on the cooling function is high, but if it is 5°C or more, the load on the air conditioner 10 is low. Therefore, in this example, 5°C is used as the judgment criterion.

[0030] As described above, when the answer to each of the branches from S10 to S14 is Yes, the load on the air conditioner 10 is low and the refrigerant passing sound becomes louder, or the refrigerant passing sound becomes clearer because other sounds are simply quieter. Therefore, when prioritizing reducing the refrigerant passing sound, the control unit 12 performs control in S-Flow control to change the target of air conditioning from only the driver's seat to the front seats (S18). More specifically, the control unit 12 performs control so that the conditioned air blown into the vehicle cabin is blown out from both the air outlets on the driver's seat and passenger's seat sides, which are the front seats.

[0031] The control unit 12 also determines whether or not the air conditioning is automatically concentrated in the front seats (S20). If the air conditioning is automatically concentrated in the front seats (Yes in S20), the process proceeds to step S22. On the other hand, if the air conditioning is not automatically concentrated in the front seats (No in S20), the process proceeds to step S30. Next, the control unit 12 determines whether or not the outside air temperature is 8°C or higher (S22). If the outside air temperature is 8°C or higher (Yes in S22), the process proceeds to step S24. On the other hand, if the outside air temperature is less than 8°C (No in S22), the process proceeds to step S30. Next, the control unit 12 determines whether or not the vehicle is stopped (S24). If the vehicle is stopped (Yes in S24), the process proceeds to step S26, and if the vehicle is not stopped (No in S24), the process proceeds to step S30. Next, the control unit 12 judges whether or not the target temperature after passing through the evaporator 14 is 8°C or higher (S26). If the target temperature after passing through the evaporator 14 is 8°C or higher (Yes in S26), the process proceeds to step S28, and if it is less than 8°C (No in S16), the process proceeds to step S30. Here, in this example, 8°C is used as the judgment criterion, but is not particularly limited. Note that the judgments in S20 to S24 above correspond to the judgments in S10 to S14, respectively.

[0032] As described above, when the answer to each of the branches of S20 to S24 is Yes, the load on the air conditioner 10 is low and the refrigerant passing sound becomes louder, or the refrigerant passing sound becomes clearer because other sounds are simply quieter. Therefore, when it is desired to prioritize reducing the refrigerant passing sound, the control unit 12 controls the S-Flow control to change the target of air conditioning from the front seats to all seats (S28). More specifically, the control unit 12 controls the conditioned air to be blown into the vehicle cabin to be blown from all seats. On the other hand, when the answer to each of the branches of the above steps is No, the state does not correspond to one in which the refrigerant passing sound becomes louder, so the control unit 12 continues the normal S-Flow control (S30).

[0033] The above description is merely an example, and in the vehicle air conditioning device disclosed in this specification, it is sufficient to increase the load on the air conditioning device 10 and suppress the generation of refrigerant passing noise by increasing the number of air outlets for blowing conditioned air into the vehicle cabin under certain conditions. Therefore, the numerical values ​​of the judgment criteria in the flowchart of FIG. 3 may be changed as appropriate. [Explanation of symbols]

[0034] 10 vehicle air conditioning system, 12 control unit, 14 evaporator, 16 compressor, 18 condenser, 20 refrigerant piping, 22 expansion valve.

Claims

1. A control unit that controls an air conditioning of a vehicle; An evaporator; A compressor and A capacitor; a refrigerant pipe that is a flow path through which a refrigerant circulates and that connects the evaporator, the compressor, and the condenser; an expansion valve provided on a path connecting the condenser and the evaporator in the refrigerant piping; Equipped with the control unit operates to concentrate the air conditioning on one seat in the vehicle interior, and controls to increase the number of air outlets for conditioned air blown into the vehicle interior when the air conditioning load is equal to or lower than a predetermined value.

1. A vehicle air conditioning system comprising:

Images