JP7478352B2 - Vehicle air conditioning system - Google Patents

Description

The present invention relates to an air conditioning system for vehicles.

In recent vehicles (automobiles), there has been an increase in electric vehicles that do not have engines (internal combustion engines) and are driven only by motors.

Even in the electric vehicle described above, it is necessary to provide air conditioning for the vehicle interior. To provide air conditioning for the vehicle interior, it is desirable to use a heat pump system that can provide both heating and cooling using a refrigerant compressed by a compressor. For this reason, a heating heat exchanger, an external heat exchanger for exchanging heat between the outside air and the refrigerant, an expansion valve for cooling, and a cooling heat exchanger are required.

Electric vehicles are also equipped with large-capacity batteries to supply power to the motor that drives the vehicle. When the battery becomes hotter than a certain temperature due to charging and discharging, the battery needs to be cooled. If the battery is cooled using a refrigerant, a battery expansion valve and a battery heat exchanger are required to cool the battery.

Patent Document 1 discloses a system in which a refrigerant for air conditioning the vehicle interior and a refrigerant for cooling the battery are provided separately. Patent Document 2 discloses a system that does not cool the battery, but switches the refrigerant path when the refrigerant pressure drops.

JP 2019-130980 A JP 2019-26118 A

To simplify the system, it is conceivable to share (commonize) the same refrigerant between the vehicle interior air conditioning and battery cooling. In this case, since a large cooling capacity is required to cool the battery, it is important to prevent the refrigerant pressure from dropping too much. However, it has been found that when the same refrigerant is used both for vehicle interior air conditioning and for battery cooling, the refrigerant pressure can drop too much, resulting in a situation where the battery cannot be sufficiently cooled.

In particular, during heating, it is easy for the pressure of the refrigerant to drop significantly after passing through the external heat exchanger that exchanges heat with the outside air. In this case, there is a concern that after the refrigerant passes through the external heat exchanger that exchanges heat with the outside air and then passes through the expansion valve for cooling the battery, the drop in the high-pressure side pressure of the refrigerant will be excessive, resulting in an insufficient flow rate of the refrigerant. If an insufficient flow rate of the refrigerant occurs, the pressure (i.e., temperature) of the refrigerant cannot be sufficiently reduced, and the cooling capacity of the heat exchanger for cooling the battery will be insufficient.

It is also possible to provide a separate bypass system that allows the refrigerant to bypass the external heat exchanger when the refrigerant pressure drops below a certain pressure, but this is not recommended as it would complicate the system and increase costs.

The present invention was made in consideration of the above circumstances, and its purpose is to provide a vehicle air conditioner that can adequately cool the battery without complicating the system, even when a refrigerant is shared between the vehicle interior air conditioning and battery cooling.

In order to achieve the above object, the present invention adopts the following first solution. That is, as described in claim 1,
A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant; and a heating heat exchanger disposed in an air conditioning passage through which air conditioning air for the vehicle interior flows and for heating the vehicle interior.
a heating expansion valve provided between the external heat exchanger and the heating heat exchanger, through which a refrigerant passes during heating;
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
When heating and cooling the battery, the refrigerant from the compressor passes through the heating heat exchanger, the heating expansion valve , the external heat exchanger , the battery expansion valve, and the battery heat exchanger in this order;
the control unit controls the switching damper to perform the inside air circulation when the refrigerant pressure detected by the pressure sensor is equal to or lower than a predetermined pressure during the heating operation and when the battery is cooled.
It is set up like this.

According to the first solution, when the refrigerant pressure is equal to or lower than a predetermined pressure, the amount of heat exchange in the heating heat exchanger is reduced by circulating the internal air, and the drop in the refrigerant pressure is suppressed. This allows the battery to be sufficiently cooled when a request for battery cooling is made. This is also preferable in terms of simplifying the system and reducing costs, compared to a case where a separate bypass system is provided in which the refrigerant bypasses the external heat exchanger when the refrigerant pressure drops to or lower than a predetermined pressure. In addition, during heating, the pressure and temperature of the refrigerant are sufficiently reduced when the refrigerant passes through the heating expansion valve, and the external heat exchanger can sufficiently absorb heat from the outside air, which is preferable in terms of efficient heating. On the other hand, since the pressure of the refrigerant is reduced both when passing through the heating expansion valve and when passing through the external heat exchanger, the refrigerant pressure is likely to drop too much, causing a decrease in the cooling capacity of the battery heat exchanger. However, by controlling to reduce the amount of heat exchange in the heating heat exchanger, the refrigerant pressure is prevented from dropping too much.

In order to achieve the above object, the present invention adopts the following second solution. That is, as described in claim 2,
A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant; and a heating heat exchanger disposed in an air conditioning passage through which air conditioning air for the vehicle interior flows and for heating the vehicle interior.
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
A humidity sensor for detecting humidity in a vehicle interior;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
The control unit is configured to control the switching damper so as to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure,
the control unit controls the switching damper so that, when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than the predetermined pressure and the humidity detected by the humidity sensor is equal to or higher than a predetermined value, the outside air is introduced for a predetermined period of time and then the inside air is circulated.
According to the second solution, it is possible to obtain substantially the same effect as the first solution. In addition, when the humidity inside the vehicle is high, the humidity is reduced by introducing outside air before the internal air circulation is started, which is preferable in preventing the front windshield from fogging up due to the internal air circulation.

Based on the above first or second solution, the following solution can be adopted. That is, as described in claim 3,
a temperature sensor for detecting a temperature of the battery;
When the temperature detected by the temperature sensor is equal to or higher than a predetermined temperature, the refrigerant flows from the battery expansion valve to the battery heat exchanger,
the control unit controls the switching damper to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure and the temperature detected by the temperature sensor is equal to or higher than the predetermined temperature.
In this case, the internal air circulation is performed only when battery cooling is required, which is preferable in terms of preventing a situation in which the ventilation volume at the heating heat exchanger is unnecessarily reduced.

In order to achieve the above object, the present invention adopts the following third solution. That is, as described in claim 4,
A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant;
a heating heat exchanger that is disposed in an air conditioning passage through which conditioned air for the vehicle interior flows and that serves to heat the vehicle interior;
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
The control unit is configured to control the switching damper so as to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure,
the passage of the refrigerant through the cooling expansion valve and the cooling heat exchanger, and the passage of the refrigerant through the battery expansion valve and the battery heat exchanger are each performed after the refrigerant has passed through the external heat exchanger;
A switching means is provided for switching a flow mode of the refrigerant after passing through the external heat exchanger among a first mode, a second mode, and a third mode,
In the first aspect, the refrigerant passes through the cooling expansion valve and the cooling heat exchanger, but does not pass through the battery expansion valve and the battery heat exchanger;
In the second aspect, the refrigerant passes through the battery expansion valve and the battery heat exchanger, but does not pass through the cooling expansion valve and the cooling heat exchanger;
In the third aspect, the refrigerant passes through the cooling expansion valve and the cooling heat exchanger, and also passes through the battery expansion valve and the battery heat exchanger,
The pressure sensor is adapted to detect a pressure of the refrigerant after passing through the external heat exchanger.
According to the third solution, it is possible to obtain substantially the same effect as the first solution. In addition, a specific path for the refrigerant is provided. The pressure sensor detects the pressure of the refrigerant after passing through the external heat exchanger, which is important for cooling the battery, and is therefore preferable for accurately determining whether or not the refrigerant pressure required for cooling the battery is sufficiently secured.

Based on the above-mentioned solutions, the following solutions can be adopted.
Further provided with an opening/closing grill shutter for changing the introduction state of the traveling wind to the external heat exchanger,
The control unit controls the grill shutter to be in a closed state when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure.
In this case, by closing the grill shutter, the amount of heat exchanged in the external heat exchanger is reduced, and the pressure drop caused when the refrigerant passes through the external heat exchanger is suppressed, so that the overall pressure drop of the refrigerant can be more sufficiently suppressed.

According to the present invention, even when the refrigerant is shared between the vehicle interior air conditioning and the battery cooling, the battery can be sufficiently cooled without complicating the system.

1 is a simplified plan view showing an example of a vehicle to which the present invention is applied; This shows an example of a refrigerant circulation system, with arrows indicating the flow of refrigerant during heating. In the example of the circulation system in FIG. 2, the flow of the refrigerant during cooling is indicated by arrows. In the example of the circulation system in FIG. 2, the flow of the refrigerant during defrosting is indicated by arrows. In the example of the circulation system in FIG. 2, the flow of the refrigerant during battery cooling is indicated by arrows. In the example of the circulation system in FIG. 2, the flow of the refrigerant when air conditioning and battery cooling are performed simultaneously is indicated by arrows. In the example of the circulation system in FIG. 2, the flow of the refrigerant when heating and cooling the battery are performed simultaneously is indicated by arrows. FIG. 2 is a diagram showing an example of a control system of the present invention. 4 is a flowchart showing a control example of the present invention. 10 is a flowchart showing a second control example of the present invention. 10 is a flowchart showing a third control example of the present invention.

Figure 1 shows an example of a vehicle V to which the present invention is applied. The vehicle V is an electric vehicle, as described below. In the figure, 1 indicates the left and right front wheels, and 2 indicates the left and right rear wheels. In Figure 1, the left side indicates the front of the vehicle.

The vehicle V has a dash panel 3 extending in the left-right direction immediately behind the front wheels 1. This dash panel 3 separates a motor storage compartment (corresponding to an engine room) 4 at the front from a passenger compartment 5 at the rear. Inside the passenger compartment 5, a driver's seat 6, a passenger seat 7, and a rear seat 8 are arranged. 9 is a steering wheel.

An instrument panel 10 extending in the left-right direction is disposed in the passenger compartment 5, positioned immediately behind the dash panel 3. An air conditioning unit 20, which will be described later, is disposed in this instrument panel 10. A large-capacity battery 21 is disposed below the floor surface of the passenger compartment 5. In this embodiment, the battery 21 is stored in a tunnel portion formed in the center of the floor panel in the vehicle width direction, but the location of the battery 21 is not particularly important.

A motor 22 is disposed in the motor storage chamber 4. The driving force of the motor 22 is transmitted to the left and right front wheels 1 via a transaxle 23 and a pair of left and right drive shafts 24. In this embodiment, the vehicle V is a FF vehicle in which the front wheels 1 are driving wheels and the rear wheels 2 are driven wheels.

An inverter 25 is attached to the motor 22. Electric power is exchanged between the battery 21 and the motor 22 via the inverter 25. That is, the motor 22 is driven to run by supplying power from the battery 21. During deceleration, the motor 22 functions as a generator to charge the battery 21 (regeneration). The vehicle V may be a rear-wheel drive vehicle or a four-wheel drive vehicle, and may have two or more drive motors, and may further use in-wheel motors.

An external heat exchanger 30 is disposed in front of the motor storage compartment 2. As described below, this external heat exchanger 30 exchanges heat between the refrigerant flowing inside it and the outside air. The external heat exchanger 30 receives the wind generated by running, enabling efficient heat exchange between the outside air and the refrigerant. In addition, a cooling fan 31 is disposed immediately behind the external heat exchanger 30. By operating this cooling fan 31, it is possible to introduce outside air into the external heat exchanger 30 even when the vehicle V is stopped.

An openable and closable grill shutter 32 is disposed immediately in front of the external heat exchanger 30 .
When the grill shutter 32 is opened, the traveling wind can be introduced into the external heat exchanger 30. When the grill shutter 32 is closed, the introduction of the traveling wind into the external heat exchanger 30 is restricted.

The grill shutter 32 basically improves the aerodynamic characteristics of the vehicle V. That is, when the grill shutter 32 is closed, the air resistance of the vehicle V is reduced. In the embodiment, the grill shutter 32 is basically closed when the vehicle speed is equal to or greater than a predetermined vehicle speed (e.g., 60 km/h), and is open when the vehicle speed is less than the predetermined vehicle speed (it is also open when the vehicle V is stopped). When the grill shutter 32 is open, the heat exchange function of the external heat exchanger 30 is improved.

The vehicle V does not have an engine (internal combustion engine) as a heat source. Therefore, the air conditioning unit 20 uses the power of the battery 21 to perform air conditioning. The air conditioning by the air conditioning unit 20 is of the heat pump type, as described below.

The battery 21 generates heat when it is charged and discharged. To protect the battery 21, it is necessary to appropriately cool the battery 21 so that its temperature does not exceed an upper limit temperature (e.g., 60°C). For this reason, the battery 21 is cooled when the temperature of the battery 21 reaches or exceeds a predetermined temperature (e.g., 50°C) that is set lower than the upper limit temperature. The battery 21 is cooled using the refrigerant (heat medium) used in the air conditioning unit 20, as described below (the refrigerant is used both for air conditioning and for cooling the battery 21).

Next, an example of a refrigerant circulation system set up for air conditioning and cooling of the battery 21 will be described with reference to FIG. 2. Note that, as the refrigerant, for example, HFC refrigerants such as R134a, HFO refrigerants such as R1234yf, and even carbon dioxide can be used.

First, the air conditioning unit 20 will be described. The air conditioning unit 20 has an air conditioning passage 41. A switching damper 42 is provided at the entrance of the air conditioning passage 41, allowing switching between introducing outside air and circulating inside air. A blower 43 is disposed in the air conditioning passage 41 near the switching damper 42. The blower 43 is driven by a motor 44. All of the various electrical devices described below are operated (driven) by receiving power from the battery 21.

In the air conditioning passage 41, a heat exchanger 45 for cooling is disposed downstream of the blower 43. The portion of the air conditioning passage 41 downstream of the heat exchanger 45 is branched into two branch passages 43A and 43B by a branch plate 46. In one branch passage 43A, a heat exchanger 47 for heating is disposed on the upstream side, and an electric heater (e.g., a PTC heater) 48 is disposed on the downstream side. The heater 47 is heated by passing electricity through it.

An air mix damper 49 is provided at the upstream end of each of the branch passages 43A and 43B. This air mix damper 49 changes the ratio between the amount of air flowing through the branch passage 43A and the amount of air flowing through the branch passage 43B (the ratio can be changed within the range of 0 to 100%).

The downstream side of each branch passage 43A and 43B is connected to the air mix chamber 50. The conditioned air in this air mix chamber is supplied to the vehicle interior from an outlet provided in the instrument panel 10, etc.

In FIG. 2, 60 is a compressor and 61 is an accumulator (gas-liquid separator). The compressor 60 draws in and compresses the refrigerant in the accumulator 61, and is an electric type that is driven by power supplied from the battery 21.

The refrigerant compressed by the compressor 60 to a high temperature and high pressure is supplied to the heating heat exchanger 47 via piping 62. The refrigerant that has passed through the heat exchanger 47 is supplied to the external heat exchanger 30 described above via piping 63. An orifice 64 that functions as an expansion valve is disposed midway along the piping 63. In addition, a bypass piping 65 that bypasses the orifice 64 is provided in the piping 63, and an electromagnetic on-off valve 66 is connected to the bypass piping 65. The orifice 64, bypass piping 65, and on-off valve 66 constitute a variable opening expansion valve that can be fully opened. The functions of the orifice 64, bypass piping 65, and on-off valve 66 can also be configured as a single valve device.

The refrigerant that has passed through the external heat exchanger 30 flows through a pipe 67 to an electromagnetic switching valve 68. Two pipes 69 and 70 are connected to the switching valve 68. The switching valve 68 selectively connects the pipe 67 to either the pipe 69 or the pipe 70.

The refrigerant flowing through one of the pipes 69 flows to the accumulator 61 via pipe 71, which serves as the return pipe. The refrigerant flowing through the other pipe 70 is supplied to the heat exchanger 45 for cooling. The refrigerant that passes through this heat exchanger 45 flows to the accumulator 61 via pipe 72 and the aforementioned pipe 71.

An electromagnetic variable opening expansion valve 73 is connected to the other pipe 70 near the heat exchanger 45. The expansion valve 73 can be switched between a completely closed state and an open state in which it is slightly opened to expand the refrigerant. The expansion valve 73 can also be made to have an opening that can be changed within a range that allows the expansion of the refrigerant.

A bypass pipe 80 is led out from the other pipe 70 at a position between the switching valve 68 and the expansion valve 73. The refrigerant flowing through this pipe 80 is supplied to a heat exchanger 81 for cooling the battery 21. The refrigerant that passes through this heat exchanger 81 flows to the accumulator 61 via a pipe 82 and the aforementioned pipe 71. The heat exchanger 81 is disposed in the vehicle body as a battery pack integrated with the battery 21.

An electromagnetic expansion valve 83 with variable opening is connected to the piping 80. The expansion valve 83 can be switched between a completely closed state and an open state in which it is slightly opened to expand the refrigerant. The expansion valve 83 can also be made to have a variable opening within a range that allows the expansion of the refrigerant.

The refrigerant circulation path is switched by appropriately switching the operating states of the aforementioned on-off valve 66, switching valve 68, and expansion valves 73 and 83. Below, the refrigerant circulation path is explained for the following cases: heating, cooling, defrosting, battery cooling, cooling + battery cooling, and heating + battery cooling.

(1) During heating, the on-off valve 66 is closed and the switching valve 68 is set to a state where it selects the pipe 69. The air mix damper 49 is set to a position where more conditioned air flows through the heat exchanger 47 for heating. Although the expansion valves 73 and 83 are closed, since no refrigerant flows through the pipes 70 and 80, the open/closed state of the expansion valves 73 and 83 does not matter.

During heating, the refrigerant flows as shown by the arrows in FIG. 2. That is, the refrigerant, which has been compressed by the compressor 60 to a high temperature and pressure, passes through the heat exchanger 47, whereby the conditioned air is heated. The refrigerant that has passed through the heat exchanger 47 is reduced in pressure and temperature by passing through the orifice 64. The reduced-pressure and cooled refrigerant exchanges heat with the outside air as it passes through the external heat exchanger 30, and is heated (heat absorption by the refrigerant). The heated refrigerant passes through the pipes 67, 69, and 71 and is returned to the accumulator 61.

(2) During cooling, the on-off valve 66 is open, the switching valve 68 selects the pipe 70, the expansion valve 73 is open, and the expansion valve 83 is closed. In addition, the air mix damper 49 is set to a position where less conditioned air flows through the heat exchanger 47 for heating.

During cooling, the refrigerant flows as shown by the arrows in FIG. 3. That is, the refrigerant compressed by the compressor 60 passes through the heat exchanger 47, but the amount of conditioned air flowing through the heat exchanger 47 is small (there may be no flow rate), and the conditioned air is hardly heated at all. The refrigerant that passes through the heat exchanger 47 bypasses the orifice 64 and flows to the external heat exchanger 30. The external heat exchanger 30 cools the refrigerant with outside air (heat release from the refrigerant).

The refrigerant that has passed through the external heat exchanger 30 passes through the switching valve 68, piping 70, and the expansion valve 73. The expansion valve 73 reduces the pressure and temperature of the refrigerant. The cooled refrigerant flows through the cooling heat exchanger 45, cooling the air-conditioned air. The refrigerant that has passed through the heat exchanger 45 is returned to the accumulator 61 via piping 72 and 71.

(3) Defrosting is when frost adhering to the external heat exchanger 30 is removed. The flow of refrigerant during defrosting is shown in FIG. 4, and is the same as during heating shown in FIG. 2, except that the refrigerant passes through the on-off valve 66, which is in an open state. Because the refrigerant bypasses the orifice 64, the temperature of the refrigerant introduced into the external heat exchanger 30 becomes significantly higher than during heating, thereby defrosting the external heat exchanger 30.

Defrosting begins when it is detected that frost has formed on the external heat exchanger 30. The sensor that detects frost can be, for example, a sensor that directly detects frost, but it can also be performed by a sensor that detects the temperature of the refrigerant. That is, for example, when operation in the heating cycle continues and the temperature of the refrigerant immediately before being introduced into the external heat exchanger 30 becomes, for example, -20°C or lower, it can be determined that frost has formed on the external heat exchanger 30. In this way, the frost formation detection sensor can detect frost directly or by estimation.

(4) When cooling the battery, the on-off valve 66 is open, the switching valve 68 selects the pipe 70, the expansion valve 73 is closed, and the expansion valve 83 is open. Battery cooling is performed when the battery temperature is equal to or higher than a predetermined temperature (e.g., 50°C).

When cooling the battery, the refrigerant flows as shown by the arrows in Figure 5. That is, the refrigerant from the compressor 60 passes through the heat exchanger 47, the on-off valve 66, the external heat exchanger 30, the switching valve 68, the pipes 70 and 80, and the expansion valve 83. The expansion valve 83 reduces the pressure and temperature of the refrigerant. The cooled refrigerant flows through the heat exchanger 81 for cooling the battery, thereby cooling the battery 21. The refrigerant that has passed through the heat exchanger 81 is returned to the accumulator 61 via the pipes 82 and 71.

During battery cooling, the refrigerant receives heat released from the battery 21 through the heat exchanger 21 for battery cooling, and releases this heat in the heat exchanger 47, thereby enabling heating of the vehicle interior. At this time, as described above, when the grille shutter 32 is open, the heat exchange function of the external heat exchanger 30 is improved, while the degree of pressure drop of the refrigerant increases. After passing through the external heat exchanger 30, the refrigerant passes through the battery expansion valve 83 and then flows to the battery heat exchanger 81, where the battery 21 is cooled. If the pressure of the refrigerant after passing through the external heat exchanger 30 is too low, the refrigerant will not be sufficiently expanded by the battery expansion valve 83, and there is a risk that the battery 21 will not be sufficiently cooled. In this way, when the refrigerant pressure immediately after passing through the external heat exchanger 30 is equal to or lower than a predetermined pressure set in advance, the grille shutter 32 is closed regardless of the vehicle speed (regardless of the basic opening and closing conditions of the grille shutter 32), and the heat exchange function of the external heat exchanger 30 is reduced. This prevents the refrigerant pressure from dropping too low, allowing the battery 21 to be cooled sufficiently.

(5) During air conditioning and battery cooling, the on-off valve 66 is open, the switching valve 68 selects the pipe 70, and the expansion valves 73 and 83 are open.

During cooling and battery cooling, the refrigerant flows as shown by the arrows in FIG. 6. That is, the refrigerant from the compressor 60 flows through the heat exchanger 47, the on-off valve 66, the external heat exchanger 30, the switching valve 68, and the piping 70. The refrigerant that flows through the piping 70 passes through the expansion valve 73, and also through the expansion valve 83 via the piping 80. The refrigerant is decompressed and cooled by the expansion valve 73. The refrigerant that has been cooled flows through the heat exchanger 45 for cooling, thereby cooling the air-conditioned air. At the same time, the refrigerant is decompressed and cooled by the expansion valve 83. The refrigerant that has been cooled flows through the heat exchanger 81 for battery cooling, thereby cooling the battery 21. The ratio of the flow rate of the refrigerant that flows through the heat exchanger 45 and the flow rate of the refrigerant that flows through the heat exchanger 81 can be changed by adjusting the opening degree of the expansion valves 73 and 83. In addition, a valve device that changes the ratio of the amount of refrigerant that flows through the expansion valve 73 and the amount of refrigerant that flows through the expansion valve 83 can be provided separately.

(6) When heating and cooling the battery, the switching valve 68 is changed from the heating state in FIG. 2 to a state in which the piping 70 is selected. Also, the expansion valve 83 is opened, while the expansion valve 73 is closed. As a result, the refrigerant, which has been cooled by passing through the expansion valve 83, passes through the heat exchanger 81 to cool the battery 21.

During heating and battery cooling, the refrigerant flow is as shown by the arrows in Figure 7. That is, compared to the heating mode shown in Figure 2, the refrigerant that has passed through the external heat exchanger 30 flows from the expansion valve 83 to the heat exchanger 81 for cooling the battery.

In this case, the refrigerant passes through the orifice 64, which functions as an expansion valve, and so it is expected that the refrigerant pressure will drop too much. That is, the refrigerant, whose pressure has been significantly reduced by the heating heat exchanger 47 and the orifice 64, will have its pressure further reduced by the external heat exchanger 30, so it is expected that the refrigerant pressure immediately after passing through the external heat exchanger 30 (i.e., the refrigerant pressure immediately upstream of the expansion valve 83) will become too small. If the refrigerant pressure drops too much in this way, it will not be possible to ensure a sufficient flow rate of the refrigerant passing through the expansion valve 83, and it will become impossible for the heat exchanger 81 to adequately cool the battery 21.

For this reason, when the refrigerant pressure (the refrigerant pressure immediately after passing through the external heat exchanger 30) is equal to or lower than a preset pressure, the amount of heat exchanged in the heating heat exchanger 47 is reduced to suppress a drop in the refrigerant pressure in the heating heat exchanger 47, as described below. Specifically, the amount of heat exchanged in the heating heat exchanger 47 is reduced by performing at least one of the following controls: control to circulate the inside air and control to reduce the volume of air-conditioned air blown by the blower 43. When heating is insufficient, the electric heater 48 can be operated.

As mentioned above, the grill shutter 32 is basically opened and closed according to the vehicle speed. However, when the refrigerant pressure is below the predetermined pressure, the grill shutter 32 can be forcibly closed, taking priority over the basic opening and closing conditions according to the vehicle speed.

When the refrigerant does not pass through the orifice 64, the pressure of the refrigerant immediately before it is introduced into the external heat exchanger 30 is sufficiently large. As a result, even if sufficient heat exchange occurs between the outside air and the refrigerant in the external heat exchanger 30, the pressure of the refrigerant immediately after passing through the external heat exchanger 30 is sufficiently secured, and no problems arise in terms of cooling the battery 21.

Various sensors S1 to S14 are provided on the refrigerant circulation path described above. Sensor S1 is a temperature sensor provided on pipe 62 to detect the temperature of the refrigerant discharged from compressor 60. Sensor S2 is a pressure sensor provided on pipe 63 to detect the pressure of the refrigerant (high pressure sensor). Sensor S3 is a temperature sensor provided near grill shutter 32 to detect the temperature of the outside air. Sensor S4 is a temperature sensor provided on pipe 67 to detect the temperature of the refrigerant immediately after passing through external heat exchanger 30. Sensor S5 is a pressure sensor provided on pipe 67 to detect the pressure of the refrigerant immediately after passing through external heat exchanger 30 (low pressure sensor).

Sensor S6 is a temperature sensor provided in the battery 21 to detect the temperature of the battery 21. Sensor S7 is a temperature sensor provided in the pipe 82 to detect the temperature of the refrigerant immediately after it has passed through the heat exchanger 81. Sensor S8 is a pressure sensor provided in the pipe 82 to detect the pressure of the refrigerant immediately after it has passed through the heat exchanger 81 for cooling the battery.

Sensor S9 is a temperature sensor provided in the cooling heat exchanger 45 to detect the temperature of the heat exchanger 45. Sensor S10 is a temperature sensor provided in the pipe 72 to detect the temperature of the refrigerant immediately after it has passed through the heat exchanger 45. Sensor S11 is a temperature sensor provided immediately downstream of the electric heater 48 to detect the temperature of the conditioned air immediately after it has passed through the heater 48.

Figure 8 shows an example of a control system for controlling air conditioning, including battery cooling. In the figure, U is a control unit configured using a microcomputer. The control unit U is equipped with a CPU as a control means, ROM as a storage means, RAM, and an interface.

In addition to the various sensors S1 to S11 described above, signals from sensors S12 to S15 are input to the control unit U. Sensor S12 is a temperature sensor that detects the temperature inside the vehicle cabin. Sensor S13 is a humidity sensor that detects the humidity inside the vehicle cabin. Sensor S14 is a solar radiation sensor installed inside the vehicle cabin that detects the amount of solar radiation. Sensor S15 is a vehicle speed sensor that detects the vehicle speed.

The control unit U also receives signals from an air conditioning operation device S16 that is operated by the occupant. The air conditioning operation device S16 is configured in the same manner as in the past, and includes, for example, an air conditioning ON/OFF switch, a temperature setting switch, an air volume change switch, an air outlet change switch, a switch for selecting either automatic mode or manual mode, and the like.

The control unit U controls the various devices shown in FIG. 8 for battery cooling and air conditioning control, and also controls the air outlet switching damper 50 for selecting the air outlet.

The control unit U appropriately controls the air conditioning, such as heating and cooling, in response to the operation of the air conditioning operating device S16. Note that the air conditioning control itself is no different from general air conditioning control, so further explanation is omitted.

The control unit U executes control to prevent the refrigerant pressure from dropping too low when battery cooling is required. An example of this control will be described with reference to the flowchart shown in Figure 9. In the following description, Q indicates a step.

First, in Q1 of FIG. 9, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is equal to or higher than a predetermined value (a predetermined temperature, for example, 50°C). If the determination in Q1 is NO, this means that battery cooling is not required, and the process is terminated.

If the answer to Q1 is YES, battery cooling is performed in Q2. That is, the refrigerant flows through the expansion valve 83 and the battery heat exchanger 81 to cool the battery 21.

After Q2, in Q3, it is determined whether the refrigerant pressure detected by the pressure sensor S5 is equal to or lower than a predetermined pressure. If the determination in Q3 is NO, it is determined in Q5 whether the temperature of the battery 21 detected by the temperature sensor S6 is lower than a predetermined value. If the determination in Q5 is NO, the process returns to Q2 (continuing battery cooling).

If the answer to Q5 above is YES, then in Q6, battery cooling is terminated (the state is changed so that refrigerant does not flow through the battery heat exchanger 81).

If the answer to Q3 is YES, the refrigerant pressure has dropped too low, causing the battery heat exchanger 81 to lack the cooling capacity (heat receiving capacity). In this case, in Q4, the rotation speed of the blower 43 is reduced to reduce the volume of air conditioning air. This reduces the amount of heat exchanged between the refrigerant and the air conditioning air in the heating heat exchanger 47, preventing the refrigerant pressure from dropping. In other words, sufficient cooling capacity is ensured in the battery heat exchanger 81, making it possible to sufficiently cool the battery 21.

In addition, in Q4, the electric heater 48 is turned on (operated) to heat the conditioned air. In other words, the lack of heating caused by the reduction in the volume of the conditioned air is compensated for by operating the electric heater 48. After Q4, the process moves to Q5.

Figure 10 shows a second control example of the present invention. The control example of Figure 10 will be described below. First, in Q11, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is equal to or higher than a predetermined value (a predetermined temperature, for example, 50°C). If the determination in Q11 is NO, this means that battery cooling is not required, and the process is terminated.

If the answer to Q11 is YES, then in Q12 it is determined whether the refrigerant pressure detected by the pressure sensor S5 is equal to or lower than a predetermined pressure. If the answer to Q12 is NO, then in Q13 battery cooling is performed. That is, the refrigerant flows through the expansion valve 83 and the battery heat exchanger 81 to cool the battery 21.

After Q13, in Q14, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is less than the predetermined value. If the result of the determination in Q14 is NO, the process returns to Q13 (continuing battery cooling).

If the answer to Q14 above is YES, then in Q15, battery cooling is terminated (the state is changed so that refrigerant does not flow through the battery heat exchanger 81).

If the answer to Q12 is YES, then in Q16 it is determined whether the humidity inside the vehicle cabin detected by the humidity sensor S13 is equal to or higher than a predetermined value (predetermined humidity, for example 70%). If the answer to Q16 is YES, then there is a high possibility that fogging will occur on the windshield, etc. In this case, in Q17 the switching damper 42 is controlled to introduce outside air. This reduces the humidity inside the cabin. After Q17, the determination in Q16 is made again.

If the answer to Q16 is NO, the humidity inside the vehicle cabin is low enough that the windshield or other surfaces do not fog up. In this case, the switching damper 42 is controlled to recirculate the air in the vehicle interior in Q18. In other words, the amount of heat exchanged in the heating heat exchanger 47 is reduced because the conditioned air introduced into the air conditioning passage 41 is relatively warmer than the outside air introduced. This prevents the refrigerant pressure from dropping.

After Q18, battery cooling is performed in Q19. That is, the refrigerant flows through the expansion valve 83 and the battery heat exchanger 81 to cool the battery 21. At this time, because the internal air is circulated, the amount of heat exchanged between the refrigerant and the air conditioning air in the heating heat exchanger 47 is reduced, and the drop in refrigerant pressure is suppressed. That is, the cooling capacity of the battery heat exchanger 81 is sufficiently ensured, making it possible to sufficiently cool the battery 21.

After Q19, in Q20, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is less than the predetermined value. If the result of the determination in Q20 is NO, the process returns to Q18 (continuing battery cooling in the internal air recirculation state). If the result of the determination in Q20 is YES, the process proceeds to Q15, where battery cooling is terminated.

Figure 11 shows a third control example of the present invention. The control example of Figure 11 will be described below. First, in Q31, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is equal to or higher than a predetermined value (a predetermined temperature, for example, 50°C). If the determination in Q31 is NO, this means that battery cooling is not required, and the process is terminated.

If the answer to Q31 is YES, then Q32 determines whether the heating mode is currently in operation. This Q32 determines whether the refrigerant pressure is likely to drop significantly.

If the answer to Q32 is NO, then in Q33, battery cooling is performed. That is, the refrigerant flows through the expansion valve 83 and the battery heat exchanger 81 to cool the battery 21.

After Q33, in Q34, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is less than the predetermined value. If the result of this determination in Q34 is NO, the process returns to Q33 (continuing battery cooling).

If the answer to Q34 above is YES, then in Q35, battery cooling is terminated (the state is changed so that refrigerant does not flow through the battery heat exchanger 81).

When the answer to Q32 is YES, that is, when there is a high possibility that the refrigerant pressure will become too low, the process proceeds to Q36. That is, in Q36, the internal air circulation is selected (corresponding to Q18 in FIG. 10), and in Q37, the blower volume is reduced and the electric heater 48 is activated (corresponding to Q4 in FIG. 9). Furthermore, in Q38, the grill shutter 32 is closed. Since the processes in Q36 to Q38 are each controls to suppress a drop in the refrigerant pressure, by executing all of these, it is possible to sufficiently suppress a drop in the refrigerant pressure, which is extremely desirable in terms of ensuring sufficient cooling capacity in the battery heat exchanger 81.

After Q39, in Q40, it is determined whether the temperature of the battery 21 detected by the temperature sensor S6 is less than the predetermined value. If the result of Q40 is NO, the process returns to Q36 (continues to cool the battery).

If the answer to the question in Q40 above is YES, then in Q35, battery cooling is terminated (the state is changed so that refrigerant does not flow through the battery heat exchanger 81).

Although the embodiment has been described above, the present invention is not limited to the embodiment, and appropriate modifications are possible within the scope of the claims. When the grill shutter 32 is closed in priority to the basic opening and closing conditions of the grill shutter 32 for battery cooling, the rotation speed (compression capacity) of the compressor 60 can be increased (for example, increased to the upper limit rotation speed) to ensure as sufficient pressure as possible for the refrigerant immediately after passing through the external heat exchanger 30.

When the grill shutter 32 is forcibly closed in priority to the basic opening and closing conditions, the pressure sensor that detects the refrigerant pressure can be, for example, pressure sensor S8 or S2 instead of pressure sensor S5. Note that it is preferable to use a pressure sensor that detects the refrigerant pressure after it has passed through the external heat exchanger 30 (pressure sensor S5 or S8 is preferable).

When both air conditioning and battery cooling are performed, it is also possible to change the cooling ratio between the air conditioning heat exchanger 45 and the battery heat exchanger 81. For example, the opening ratio between the expansion valves 73 and 83 can be changed, or a separate flow rate adjustment valve can be provided (for example, an adjustment valve for changing the distribution ratio can be provided at the junction (branch) of the pipes 70 and 80).

The basic opening and closing conditions of the grill shutter 32 may be set according to the outside air temperature instead of the vehicle speed, or may be set according to both the vehicle speed and the outside air temperature. For example, when setting according to the outside air temperature, the grill shutter 32 can be set to be closed when the outside air temperature is a low temperature below a predetermined temperature, and to be open when the outside air temperature is a high temperature above the predetermined temperature. In addition, while the grill shutter 32 is set to be closed when the vehicle speed is above a predetermined vehicle speed, this predetermined vehicle speed can be changed according to the outside air temperature. In this case, the lower the outside air temperature, the lower the predetermined vehicle speed is, and the grill shutter can be set to be fully closed when the outside air temperature is a low temperature below a predetermined temperature. In addition, the grill shutter 32 is not limited to two types, a fully closed state and a fully open state, and the opening degree can be changed in three or more stages based on at least one of the vehicle speed and the outside air temperature, and the opening degree can also be changed in a continuously variable manner.

When performing defogging, the refrigerant flow is basically the same as when performing heating, and when the humidity is high, the refrigerant can be made to pass through the cooling heat exchanger 45 as well (dehumidification). The compressor 60 is not limited to being driven by an electric motor powered by the battery 21, and may be driven using part of the power of the driving source for traveling. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferable or expressed as an advantage.

The present invention is suitable as an air conditioning system for electric vehicles that do not have engines.

V: vehicle 20: air conditioning unit 21: battery 22: motor 30: external heat exchanger 31: cooling fan 32: grille shutter 40 air conditioning unit 41: air conditioning passage 42: switching damper (for switching between internal air circulation and external air introduction)
43: Blower (for changing air volume)
45: Heat exchanger (for cooling)
47: Heat exchanger (for heating)
60: Compressor 64: Orifice (expansion valve)
65: Bypass piping 66: On-off valve 68: Switching valve 73: Expansion valve (for cooling)
81: Heat exchanger (for cooling batteries)
83: Expansion valve (for cooling batteries)

Claims (5)

A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant; and a heating heat exchanger disposed in an air conditioning passage through which air conditioning air for the vehicle interior flows and for heating the vehicle interior.
a heating expansion valve provided between the external heat exchanger and the heating heat exchanger, through which a refrigerant passes during heating;
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
When heating and cooling the battery, the refrigerant from the compressor passes through the heating heat exchanger, the heating expansion valve, the external heat exchanger , the battery expansion valve, and the battery heat exchanger in this order;
the control unit controls the switching damper to perform the inside air circulation when the refrigerant pressure detected by the pressure sensor is equal to or lower than a predetermined pressure during the heating operation and when the battery is cooled.
1. A vehicle air conditioning system comprising:
A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant; and a heating heat exchanger disposed in an air conditioning passage through which air conditioning air for the vehicle interior flows and for heating the vehicle interior.
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
A humidity sensor for detecting humidity in a vehicle interior;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
The control unit is configured to control the switching damper so as to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure,
the control unit controls the switching damper so that, when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than the predetermined pressure and the humidity detected by the humidity sensor is equal to or higher than a predetermined value, the outside air is introduced for a predetermined period of time and then the inside air is circulated.
1. A vehicle air conditioning system comprising: In claim 1 or 2,
a temperature sensor for detecting a temperature of the battery;
When the temperature detected by the temperature sensor is equal to or higher than a predetermined temperature, the refrigerant flows from the battery expansion valve to the battery heat exchanger,
the control unit controls the switching damper to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure and the temperature detected by the temperature sensor is equal to or higher than the predetermined temperature.
1. A vehicle air conditioning system comprising: A battery that serves as a power supply source for a motor for driving the vehicle;
A compressor that compresses a refrigerant;
an external heat exchanger capable of introducing airflow while the vehicle is running and for exchanging heat between the outside air and the refrigerant;
a heating heat exchanger that is disposed in an air conditioning passage through which conditioned air for the vehicle interior flows and that serves to heat the vehicle interior;
a cooling expansion valve for cooling the interior of a vehicle and a cooling heat exchanger disposed in the air conditioning passage;
a battery expansion valve and a battery heat exchanger for cooling the battery;
a switching damper for switching the introduction of conditioned air into the air conditioning passage between an outside air introduction and an inside air circulation;
A control unit;
a pressure sensor for detecting the pressure of the refrigerant;
Equipped with
a refrigerant is shared among the external heat exchanger, the heating heat exchanger, the cooling heat exchanger, and the battery heat exchanger;
The control unit is configured to control the switching damper so as to perform the inside air circulation when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure,
the passage of the refrigerant through the cooling expansion valve and the cooling heat exchanger, and the passage of the refrigerant through the battery expansion valve and the battery heat exchanger are each performed after the refrigerant has passed through the external heat exchanger;
A switching means is provided for switching a flow mode of the refrigerant after passing through the external heat exchanger among a first mode, a second mode, and a third mode,
In the first aspect, the refrigerant passes through the cooling expansion valve and the cooling heat exchanger, but does not pass through the battery expansion valve and the battery heat exchanger;
In the second aspect, the refrigerant passes through the battery expansion valve and the battery heat exchanger, but does not pass through the cooling expansion valve and the cooling heat exchanger,
In the third aspect, the refrigerant passes through the cooling expansion valve and the cooling heat exchanger, and also passes through the battery expansion valve and the battery heat exchanger,
The pressure sensor is adapted to detect the pressure of the refrigerant after passing through the external heat exchanger.
1. A vehicle air conditioning system comprising: In any one of claims 1 to 4 ,
Further provided with an opening/closing grill shutter for changing the introduction state of the traveling wind to the external heat exchanger,
The control unit controls the grill shutter to be in a closed state when the pressure of the refrigerant detected by the pressure sensor is equal to or lower than a predetermined pressure.
1. A vehicle air conditioning system comprising:

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