Air conditioning systems for railway vehicles

Abstract

The objective is to provide an air conditioning system for railway vehicles that can adjust its cooling capacity according to the heat load of the indoor air conditioning and heat-generating elements, without using complex devices that are costly or prone to malfunction. [Solution] The air conditioning system for railway vehicles includes a compressor for compressing a refrigerant, a condenser for condensing the refrigerant from the compressor by heat exchange, a pressure reducing device for reducing the pressure of the refrigerant from the condenser, an evaporator for cooling the air inside the railway vehicle with the refrigerant from the pressure reducing device, and a battery cooling device connected in parallel with the evaporator for cooling the battery with the refrigerant from the pressure reducing device.

Description

Technical Field

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[0001] Embodiments of the present invention relate to an air conditioner for railway vehicles in railway vehicles.

Background Art

[0002] In recent years, railway vehicles may be equipped with a battery as a power source. Since the battery is a heat generating body and needs to be cooled, there are methods of cooling using a water-cooled heat sink and methods of cooling by diverting the refrigerant for air conditioning of the air conditioner. In the method of cooling by diverting the refrigerant for air conditioning of the air conditioner, since the heat load on the air conditioning side and the heat load on the battery side always change, it is necessary to appropriately adjust the cooling capacity.

[0003] For example, in Patent Document 1, the refrigerant flow rate is controlled by changing the rotation speed of the compressor to adjust the cooling capacity. In Patent Document 2, the cooling capacity is adjusted by providing a configuration capable of blocking the refrigerant flowing through the air conditioning side and the battery side respectively. Further, in Patent Document 3, the cooling capacity on the battery side is adjusted by increasing or decreasing the air volume on the air conditioning side.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional method of cooling by diverting the refrigerant for air conditioning, there are difficulties in adjusting the cooling capacity. For example, in Patent Document 1, the compressor rotation speed is changed, which alters the cooling capacity of the entire refrigeration cycle. Therefore, it is difficult to adjust the cooling capacity for each system, such as only the air conditioning side or only the battery side.

[0006] Furthermore, while Patent Document 2 describes how it is possible to adjust the cooling capacity for each system by shutting off the refrigerant flowing to the air conditioning side and the battery side, respectively, this requires a device to switch the pipelines in order to shut off the refrigerant, which presents challenges such as increased system complexity, potential for failures, and increased costs. Moreover, while Patent Document 3 describes how it is possible to adjust the cooling capacity by increasing or decreasing the airflow, the amount of cooling capacity that can be adjusted by airflow is not large, and there is a problem of a time delay in response to large instantaneous heat load fluctuations.

[0007] The present invention has been made in view of the above, and aims to provide a railway vehicle air conditioning system that uses refrigerant for air conditioning to cool a heat-generating element, which can adjust the cooling capacity according to the heat load of the indoor air conditioning and the heat-generating element without using complex devices that are costly or prone to failure. [Means for solving the problem]

[0008] The railway vehicle air conditioning system of this embodiment includes a compressor for compressing a refrigerant, a condenser for condensing the refrigerant from the compressor by heat exchange, a pressure reducing device for reducing the pressure of the refrigerant from the condenser, an evaporator for cooling the air inside the railway vehicle with the refrigerant from the pressure reducing device, and a battery cooling device connected in parallel with the evaporator for cooling the battery with the refrigerant from the pressure reducing device. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a diagram showing the configuration of an air conditioning system for a railway vehicle according to the first embodiment. [Figure 2] Figure 2 shows the changes in room temperature and battery temperature in response to thermal load fluctuations of the refrigeration cycle system in the first embodiment. [Figure 3]Figure 3 is a diagram showing the configuration of a railway vehicle air conditioning system according to the second embodiment. [Figure 4] Figure 4 shows the changes in room temperature and battery temperature in response to thermal load fluctuations of the refrigeration cycle system in the second embodiment. [Figure 5] Figure 5 is a diagram showing the configuration of a railway vehicle air conditioning system according to the third embodiment. [Figure 6] Figure 6 shows the changes in room temperature and battery temperature in response to thermal load fluctuations of the refrigeration cycle system in the third embodiment. [Figure 7] Figure 7 is a diagram showing a modified configuration of the railway vehicle air conditioning system according to the first embodiment. [Figure 8] Figure 8 is a diagram showing a modified configuration of the second embodiment of the air conditioning system for railway vehicles. [Figure 9] Figure 9 is a diagram showing a modified configuration of the third embodiment of the air conditioning system for railway vehicles. [Modes for carrying out the invention]

[0010] The embodiments will be described below with reference to the drawings. Figure 1 is a diagram showing the configuration of an air conditioning system for a railway vehicle according to the first embodiment. A railway vehicle air conditioning system comprises a compressor 1, a condenser 2, a pressure reducing device 3, an evaporator 4, and a battery cooling device 5, and these components constitute a refrigeration cycle system.

[0011] In the refrigeration cycle system, the discharge port of compressor 1 is connected to the inlet of condenser 2, the outlet of condenser 2 is connected to the inlet of pressure reducing device 3, the outlet of pressure reducing device 3 is connected in parallel to the inlet of evaporator 4 and the inlet of battery cooling device 5, and the outlets of evaporator 4 and battery cooling device 5 merge and are connected to the suction port of compressor 1.

[0012] The compressor 1 is, for example, a compressor that compresses the refrigerant drawn in from the compressor's inlet to make it a high-temperature, high-pressure gaseous refrigerant that is easily liquefied even at room temperature. The condenser 2 releases heat through heat exchange between the high-temperature and high-pressure gaseous refrigerant sent from the compressor, which is the compressor 1, and the cold air flowing in from the outside, and turns it into a normal-temperature and high-pressure liquid refrigerant.

[0013] The decompression device 3 is, for example, an expansion valve. It reduces the pressure and expands the normal-temperature and high-pressure liquid refrigerant sent from the condenser 2 so that it is likely to vaporize. By using an expansion valve, temperature control becomes possible, and it is possible to cope with large heat load fluctuations of the heat-generating battery.

[0014] The evaporator 4 cools the surrounding air by vaporizing through heat exchange between the low-temperature and low-pressure liquid refrigerant sent from the decompression device 3 and the surrounding air, and the interior of the vehicle is cooled by blowing this cold air into the vehicle.

[0015] The battery cooling device 5 has a battery and a heat sink, and cools the battery through heat exchange by allowing the low-temperature and low-pressure liquid refrigerant sent from the decompression device to flow into the heat sink in contact with the battery.

[0016] The evaporator 4 and the battery cooling device 5 are connected in parallel, and the gaseous refrigerant heated by the evaporator 4 and the battery cooling device 5 merges on the outlet side of each and returns to the compressor, which is the compressor 1.

[0017] Next, the flow of the refrigerant in the refrigeration cycle will be described. The refrigerant compressed by the compressor 1 flows to the condenser 2. In the condenser 2, the refrigerant is cooled through heat exchange with the cold air flowing in from the outside and flows to the decompression device (expansion valve) 3. In the decompression device (expansion valve) 3, the refrigerant is decompressed and flows to the evaporator 4 and the battery cooling device 5 connected in parallel. In the evaporator 4, the refrigerant is heated through heat exchange with the air inside the vehicle and flows to the compressor 1. In the battery cooling device 5, the refrigerant is heated through heat exchange with the battery and flows to the compressor 1. In the compressor 1, the refrigerant is compressed again and circulates in the same way.

[0018] Figure 2 shows the change in the interior temperature and the change in the battery temperature with respect to the heat load fluctuation of the refrigeration cycle system in the first embodiment. In Figure 2, when the battery's heat output is constant and the battery's thermal load fluctuation is 0%, changes in the room's thermal load, such as changes in the number of passengers, cause a change in the battery's temperature in accordance with the change in room temperature. In particular, the temperature change became larger when the room's thermal load decreased. Furthermore, when the battery's heat output changed, resulting in a thermal load fluctuation of -33% or 33%, the battery's temperature changed significantly, but the room temperature did not.

[0019] As described above, in the refrigeration cycle system of a railway vehicle air conditioning system, by connecting a battery cooling device in parallel with the evaporator, it becomes possible to cool the heat-generating battery with a simple system configuration. Furthermore, the temperature fluctuations inside the cabin due to fluctuations in the battery's thermal load are small, and the impact on passenger comfort can be minimized.

[0020] Next, a second embodiment will be described. Figure 3 is a diagram showing the configuration of the railway vehicle air conditioning system according to the second embodiment. The same reference numerals are used for parts that are the same as in the first embodiment, and their detailed descriptions are omitted.

[0021] In Figure 3, the difference from the first embodiment is that the expansion valve, which is the pressure reducing device 3, is provided in both the system where the evaporator 4 is installed and the system where the battery cooling device 5 is installed. In other words, the second embodiment makes it possible to independently control the temperature of the first expansion valve 3-1 in the system where the evaporator 4 is provided and the second expansion valve 3-2 in the system where the battery cooling device 5 is provided.

[0022] Next, we will explain the flow of refrigerant in the refrigeration cycle. The refrigerant compressed in compressor 1 flows to condenser 2. In condenser 2, the refrigerant is cooled by heat exchange with cold air flowing in from the outside and flows to the first pressure reducing device (expansion valve) 3-1 and the second pressure reducing device (expansion valve) 3-2. In the first pressure reducing device (expansion valve) 3-1, the refrigerant is depressurized and flows to evaporator 4. In the second pressure reducing device (expansion valve) 3-2, the refrigerant is depressurized and flows to battery cooling device 5. In evaporator 4, the refrigerant is heated by heat exchange with the air inside the vehicle and flows to compressor 1. In battery cooling device 5, the refrigerant is heated by heat exchange with the battery and flows to compressor 1. In compressor 1, the refrigerant is compressed again and circulates in the same manner.

[0023] Figure 4 shows the changes in room temperature and battery temperature in response to thermal load fluctuations of the refrigeration cycle system in the second embodiment. In Figure 4, when the heat output of the battery is constant and the battery's thermal load fluctuation is 0%, when the thermal load in the room fluctuates due to changes in the number of passengers, etc., the battery's temperature changes in accordance with the room temperature change. However, the temperature change is smaller compared to the first embodiment. Furthermore, when the battery's heat output changes, the battery's thermal load fluctuation is -33% or 33%, a temperature change occurs in the battery, but this temperature change is smaller compared to the first embodiment.

[0024] As described above, in a refrigeration cycle system for railway vehicle air conditioning, by providing a pressure reducing device in each system that connects a battery cooling device in parallel with the evaporator, it becomes possible to cool the battery, which is a heat-generating element. Furthermore, the temperature fluctuations inside the cabin due to fluctuations in the battery's thermal load are small, and the impact on passenger comfort can be minimized.

[0025] Next, a third embodiment will be described. Figure 5 is a diagram showing the configuration of the railway vehicle air conditioning system according to the third embodiment. The same reference numerals are used for parts that are the same as in the first embodiment, and their detailed descriptions are omitted.

[0026] In Figure 5, the difference from the first embodiment is that the evaporator 4 and the battery cooling device 5 are connected in series. In other words, in the third embodiment, an expansion valve 3 is provided in a system in which the evaporator 4 and the battery cooling device 5 are connected in series, and the temperature can be controlled by the expansion valve 3.

[0027] Next, we will explain the flow of refrigerant in the refrigeration cycle. The refrigerant compressed in compressor 1 flows to condenser 2. In condenser 2, the refrigerant is cooled by heat exchange with cold air flowing in from the outside and flows to pressure reducing device (expansion valve) 3. In pressure reducing device (expansion valve) 3, the refrigerant is depressurized and flows to evaporator 4 and battery cooling device 5. In evaporator 4, the refrigerant is heated by heat exchange with the air inside the vehicle, and further heated by heat exchange with the battery in battery cooling device 5 before flowing to compressor 1. In compressor 1, the refrigerant is compressed again and circulates in the same manner.

[0028] Figure 6 shows the changes in room temperature and battery temperature in response to thermal load fluctuations of the refrigeration cycle system in the second embodiment. In Figure 6, when the battery's heat output is constant and the battery's thermal load fluctuation is 0%, changes in the room's thermal load, such as changes in the number of passengers, cause a change in the battery's temperature in accordance with the change in room temperature. While the temperature change increases with a larger room thermal load, the temperature change is smaller compared to the first embodiment when considering the overall thermal load fluctuation, including when the thermal load is small. Furthermore, when the battery's heat output changes, the battery's thermal load fluctuation is -33% or 33%, a temperature change occurs in the battery, but this temperature change is smaller compared to the first embodiment.

[0029] As described above, in a refrigeration cycle system for railway vehicle air conditioning, by installing a pressure reducing device in a system where the evaporator and the battery cooling device are connected in series, it becomes possible to cool the heat-generating battery with a simple system configuration. Furthermore, the temperature fluctuations inside the cabin due to fluctuations in the battery's thermal load are small, minimizing the impact on passenger comfort.

[0030] Next, modifications of the above embodiments will be described. Figure 7 is a configuration diagram of a modified version of the railway vehicle air conditioning system according to the first embodiment. Figure 8 is a configuration diagram of a modified version of the railway vehicle air conditioning system according to the second embodiment. Figure 9 is a configuration diagram of a modified version of the railway vehicle air conditioning system according to the third embodiment. The same reference numerals are used for parts that are the same as in each embodiment, and their detailed descriptions are omitted.

[0031] In Figures 7 to 9, the difference from each embodiment is that a heat-generating element is provided in the battery cooling device. In other words, in the first to third embodiments, it can be confirmed that fluctuations in the thermal load of one battery or one room affect the temperature of the other battery or room. Therefore, by installing a heat-generating element 6 in conjunction with the battery cooling device 5, the heat-generating element 6 is controlled to reduce fluctuations in the thermal load in response to changes in the heat generated by the battery.

[0032] As the heating element 6, for example, a hot wire type heater is used, and the amount of heat generated by the heater is controlled to increase or decrease in response to changes in the battery temperature. When the battery temperature is low, the amount of heat generated by the heater is controlled to increase, and when the battery temperature is high, the amount of heat generated by the heater is controlled to decrease.

[0033] For example, by controlling the combined heat output from the battery and the heater to remain constant, the heat output from the battery cooling system can be kept constant, simplifying temperature control for railway vehicle air conditioning systems.

[0034] Furthermore, although the temperature response will be lower compared to a heater, the amount of heat generated on the battery cooling device can be kept constant by utilizing the waste heat installed in the railway vehicle. For example, it is possible to utilize the waste heat from the motor and inverter. When utilizing the waste heat from the motor and inverter, it is possible to configure the system to guide heat to the battery cooling device 5 by heat conduction using a heat transfer plate, or by switching the path of the waste heat to guide heat to the battery cooling device 5.

[0035] Furthermore, the temperature information used for temperature control can be simplified by performing temperature control based on the output of a temperature sensor that detects the battery temperature. As described above, by providing a heat-generating element in the battery cooling device of a refrigeration cycle system for railway vehicle air conditioning, temperature fluctuations can be reduced, and temperature control of the railway vehicle air conditioning system can be simplified.

[0036] Although embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0037] 1. Compressor 2. Condenser 3. Pressure reducing device 4. Evaporator 5...Storage battery cooling device 6. Heat-generating components

Claims

1. A compressor that compresses the refrigerant, A condenser that condenses the refrigerant from the compressor by heat exchange, A pressure reducing device for reducing the pressure of the refrigerant from the condenser, An evaporator that cools the air inside the railway vehicle with a refrigerant from the aforementioned pressure reducing device, An air conditioning system for a railway vehicle, comprising a battery cooling device connected in parallel with the evaporator and cooling the battery with a refrigerant from the pressure reducing device.

2. A compressor that compresses the refrigerant, A condenser that condenses the refrigerant from the compressor by heat exchange, A first pressure reducing device for reducing the pressure of the refrigerant from the condenser, A second pressure reducing device for reducing the pressure of the refrigerant from the condenser, An evaporator that cools the air inside the railway vehicle with a refrigerant from the first pressure reducing device, An air conditioning system for a railway vehicle, comprising a battery cooling device connected in parallel with the evaporator and cooling the battery with a refrigerant from the second pressure reducing device.

3. A compressor that compresses the refrigerant, A condenser that condenses the refrigerant from the compressor by heat exchange, A pressure reducing device for reducing the pressure of the refrigerant from the condenser, An evaporator that cools the air inside the railway vehicle with a refrigerant from the aforementioned pressure reducing device, An air conditioning system for a railway vehicle, comprising a battery cooling device connected in series with the evaporator, which cools the battery with a refrigerant from the evaporator.

4. The aforementioned battery cooling device has a heat-generating element, The air conditioning system for railway vehicles according to any one of claims 1 to 3, wherein the heating element is controlled so that the amount of heat generated by the battery and the amount of heat generated by the heating element are equal to a predetermined value.

5. The air conditioning system for railway vehicles according to claim 4, wherein the heat-generating member is a heater.

6. The heating element guides the exhaust heat from onboard equipment mounted on the railway vehicle to the battery cooling device, as described in claim 4.

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