Railway vehicle air conditioning device, railway vehicle air conditioning system, and control method

Abstract

A railway vehicle air conditioning device according to the present disclosure comprises: a compressor; a condenser; an electronic expansion valve that has a valve body for adjusting the opening degree of a flow path through which a refrigerant flows in and a valve seat for adjusting the amount of the refrigerant flowing in by adjustment of the distance between the valve body and the valve seat and that reduces the pressure of the refrigerant flowing in from the condenser so as to lower the temperature of the refrigerant; an evaporator; and a control unit that adjusts the opening degree of the electronic expansion valve and an initialization process for fully closing the valve body and the valve seat of the electronic expansion valve when power has been supplied. The control unit totals the number of pulses during the initialization process performed when power has been supplied and the number of times a pulse signal for adjusting the opening degree of the electronic expansion valve has been supplied, so as to calculate an accumulated value and outputs a signal when the accumulated value exceeds a threshold value. A notification unit that reports an alarm in response to the signal from the control unit is provided.

Description

Air conditioning device for railway vehicles, air conditioning system for railway vehicles, and control method

[0001] The present disclosure relates to an air conditioning system for a railway vehicle.

[0002] Air conditioners use expansion valves to reduce the pressure of refrigerant and discharge it at low temperature and pressure. Because the refrigerant flow rate in the refrigeration cycle must be precisely adjusted, electronic expansion valves are used. The use of electronic expansion valves in air conditioners can improve the performance of the air conditioner.

[0003] The electronic expansion valve undergoes an initialization process as disclosed in Patent Document 1 when the air conditioner starts operating, etc. In the initialization process, the valve element of the electronic expansion valve is pressed against the valve seat. By performing the initialization process, the absolute angle of the electronic expansion valve can be accurately detected when the air conditioner starts operating, etc.

[0004] In recent years, the application of electronic expansion valves to air conditioning systems installed in railway vehicles has been considered. When initializing an electronic expansion valve while the railway vehicle is in operation, the electronic expansion valve is subjected to both a force pressing the valve disc against the valve seat due to vibrations during operation and a force due to the vibrations of the railway vehicle. Electronic expansion valves are susceptible to damage due to the force pressing the valve disc against the valve seat and the force due to vibrations of the railway vehicle, but conventional air conditioning systems do not take these factors into consideration.

[0005] JP 2020-133927 A

[0006] There was a problem that if the electronic expansion valve was damaged while the train was in operation, it would become impossible to regulate the temperature inside the train.

[0007] The present disclosure has been made to solve such problems, and aims to provide an air conditioning system for railway vehicles that can prevent damage to an electronic expansion valve while the railway vehicle is in operation.

[0008] The air conditioning system for railway vehicles according to the present disclosure has a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor through heat exchange, a valve body that adjusts the opening of a flow path through which the refrigerant flows in, and a valve seat whose distance from the valve body is adjusted to adjust the amount of refrigerant flowing in, and is equipped with an electronic expansion valve that reduces the pressure of the refrigerant flowing in from the condenser to reduce its temperature, an evaporator that evaporates the refrigerant and exchanges heat between the evaporated refrigerant and air, and a control unit that performs an initialization process to fully close the valve body and valve seat of the electronic expansion valve when power is turned on and adjusts the opening of the electronic expansion valve, and the control unit calculates an integrated value by integrating the number of pulse signals of the initialization process that is performed when power is turned on and the number of times a pulse signal is input to adjust the opening of the electronic expansion valve, and is equipped with an alarm unit that outputs a signal if the integrated value exceeds a threshold value and issues an alarm based on the signal from the control unit.

[0009] The control method according to the present disclosure includes the steps of counting the number of initialization processes that fully close the valve body and valve seat of an electronic expansion valve that is performed when power is turned on and that has a valve body that adjusts the opening of a flow path through which refrigerant flows in and a valve seat in which the amount of refrigerant flowing in is adjusted by adjusting the distance between the valve body, and that reduces the pressure of the refrigerant flowing in from a condenser to reduce its temperature, counting the number of pulse signals that adjust the opening of the electronic expansion valve, calculating an integrated value by accumulating the number of pulse signals of the initialization process that is performed when power is turned on and the number of pulse signals that adjust the opening of the electronic expansion valve, and outputting a signal to an alarm unit if the integrated value exceeds a threshold value.

[0010] According to the railway vehicle air conditioning device of the present disclosure, by notifying that the number of pulse signal inputs exceeds a threshold before the electronic expansion valve is damaged, it is possible to prevent breakdown of the railway vehicle air conditioning device during operation.

[0011] FIG. 1 is a schematic diagram showing the overall configuration of a railway vehicle air conditioning system according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view showing the structure of an electronic expansion valve of the railway vehicle air conditioning system according to the first embodiment of the present disclosure. FIG. 3 is a cross-sectional view showing a refrigerant flow path in an electronic expansion valve of the railway vehicle air conditioning system according to the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view showing the position of a valve body during an initialization process of the railway vehicle air conditioning system according to the first embodiment of the present disclosure. FIG. 5 is a flowchart showing the initialization process of the railway vehicle air conditioning system according to the first embodiment of the present disclosure. FIG. 6 is a schematic diagram showing the overall configuration of a railway vehicle air conditioning system according to the first embodiment of the present disclosure. FIG. 7 is a cross-sectional view showing the structure of an electronic expansion valve of the railway vehicle air conditioning system according to the second embodiment of the present disclosure. FIG. 8 is a cross-sectional view showing the position of a valve body during an initialization process of the railway vehicle air conditioning system according to the second embodiment of the present disclosure. FIG. 9 is a top view showing a stopper of the railway vehicle air conditioning system according to the second embodiment of the present disclosure. FIG. 10 is a cross-sectional view showing another configuration of the stopper of the railway vehicle air conditioning system according to the second embodiment of the present disclosure. 11 is a schematic diagram showing another configuration of a capillary tube of a railway vehicle air conditioning device according to a third embodiment of the present disclosure. FIG.

[0012] Hereinafter, a railway vehicle air conditioning system according to a first embodiment of the present disclosure will be described with reference to the drawings.

[0013] Embodiment 1. FIG. 1 is a schematic diagram showing the overall configuration of a railway vehicle air conditioning system according to embodiment 1 of the present disclosure. As shown in FIG. 1, the railway vehicle air conditioning system 100 includes a compressor 1, a condenser 2, an electronic expansion valve 3, an evaporator 4, a control unit 5, and a notification unit 6. The compressor 1 compresses a refrigerant. The compressor 1 may be driven at a constant speed, but because fine control is required, it is preferably an inverter-driven compressor capable of varying its rotational speed. The condenser 2 condenses the refrigerant compressed by the compressor 1 through heat exchange. The electronic expansion valve 3 reduces the pressure of the refrigerant flowing in from the condenser 2 to a low temperature. The evaporator 4 evaporates the refrigerant and exchanges heat between the evaporated refrigerant and air. The compressor 1, the condenser 2, the electronic expansion valve 3, and the evaporator 4 are connected to each other by piping to form a refrigerant circuit. The control unit 5 controls the compressor 1, the condenser 2, the electronic expansion valve 3, and the evaporator 4. The control unit 5 performs an initialization process and adjusts the opening degree of the electronic expansion valve 3. The initialization process is a process of fully closing the valve body and valve seat of the electronic expansion valve 3 when power is turned on to start operation of the air conditioner. By performing the initialization process, the opening degree of the electronic expansion valve 3 can be determined when operation of the air conditioner starts. The notification unit 6 issues an alarm based on a signal from the control unit 5. Note that the signal issued from the control unit 5 will be described later. The notification unit 6 may output an alarm using light, sound, highlighted text, or the like, and this alarm may be output to a monitor installed on the railway vehicle or to a device installed in a ground-side control facility. Furthermore, this alarm may be output to indicate, for example, that the electronic expansion valve 3 is degraded.

[0014] The railcar air conditioning system 100 also includes a power supply, a pressure sensor 9, and a temperature sensor 10. The power supplies are a main power supply 7 and an auxiliary power supply 8. The main power supply 7 supplies power to the compressor 1, the electronic expansion valve 3, and the control unit 5. The main power supply 7 is configured to receive power from, for example, the overhead lines of the railcar. The auxiliary power supply 8 is a power supply, such as a battery, that supplies power to the control unit 5 when the power supply from the main power supply 7 is cut off due to a momentary power outage or when the main power supply 7 is turned off. The auxiliary power supply 8 is controlled to be turned on when the railcar main body starts operating and turned off when the railcar stops operating. Therefore, the control unit 5 can always operate while the railcar is operating, thanks to the main power supply 7 and the auxiliary power supply 8.

[0015] The pressure sensor 9 is a sensor that detects the pressure of the refrigerant flowing into the compressor 1. The temperature sensor 10 is a sensor that detects the pressure of the refrigerant flowing into the compressor 1. When the control unit 5 receives a signal to change the temperature inside the railway vehicle, it controls the compressor 1 and the electronic expansion valve 3 based on the values ​​of the pressure sensor 9 and the temperature sensor 10.

[0016] In the railcar air conditioning system 100, refrigerant flows through a refrigerant circuit that connects a compressor 1, a condenser 2, an electronic expansion valve 3, and an evaporator 4 with piping. The refrigerant is first compressed by the compressor 1 to become a high-temperature, high-pressure gas. The gaseous refrigerant is condensed and liquefied by the condenser 2, and then expanded and decompressed by the electronic expansion valve 3 to become a low-temperature, low-pressure two-phase refrigerant. The railcar air conditioning system 100 uses a cycle in which the two-phase refrigerant is evaporated into a gas by the evaporator and returned to the compressor.

[0017] The rotation speed of the compressor 1 and the opening degree of the electronic expansion valve 3 are controlled by the control unit 5. In order to adjust the opening degree of the electronic expansion valve 3, the control unit 5 outputs a pulse signal to the electronic expansion valve 3. At this time, the opening degree of the electronic expansion valve 3 is adjusted by the width and number of pulse signals.

[0018] The rotation speed of the compressor 1 is adjusted so that the deviation between the interior temperature detected by a temperature sensor in the interior of the railcar and the set temperature of the railcar air conditioner 100 falls within a predetermined temperature range. The opening degree of the electronic expansion valve 3 is controlled by the degree of superheat. The degree of superheat is an index calculated by subtracting the evaporation temperature of the refrigerant in the evaporator 4 from the intake temperature of the refrigerant in the compressor 1, and is used to adjust the temperature in the interior of the railcar. The control unit 5 acquires the refrigerant pressure from the pressure sensor 9 and calculates the evaporation temperature, and adjusts the opening degree of the electronic expansion valve 3 so that the degree of superheat, calculated by acquiring the refrigerant intake temperature from the temperature sensor 10, is equal to or greater than a predetermined value. The control unit 5 adjusts the rotation speed of the compressor 1 so that the deviation between the interior temperature detected by the temperature sensor in the interior of the railcar and the set temperature of the railcar air conditioner 10 falls within a predetermined temperature range. However, because the degree of superheat changes when the rotation speed of the compressor 1 changes, the opening degree of the electronic expansion valve 3 changes depending on the degree of superheat. The control unit 5 controls the equipment of the railway vehicle air conditioning system 100 in accordance with commands from a controller that instructs, for example, temperature change, heating operation, cooling operation, ventilation operation, and the like.

[0019] 2 is a cross-sectional view showing the structure of an electronic expansion valve of a railway vehicle air conditioning system according to the first embodiment of the present disclosure. As shown in Fig. 2, the electronic expansion valve 3 includes a valve element 14, a valve seat 15, a spring 16, a screw 17, an output shaft 18, a gear 19, a rotor 20, a coil 21, a holder 22, and a support member 23. The valve element 14 adjusts the opening degree of the electronic expansion valve 3. The amount of refrigerant flowing into the valve seat 15 is adjusted by adjusting the distance between the valve element 14 and the valve seat 15.

[0020] 3 is a cross-sectional view showing the refrigerant flow path within the electronic expansion valve of the railway vehicle air conditioner according to the first embodiment of the present disclosure. After the refrigerant flows into the electronic expansion valve 3 through the inlet, the refrigerant moves in the direction of the arrow in FIG. 3. The refrigerant then passes through the valve seat 15 and flows out of the electronic expansion valve 3 through the outlet.

[0021] In the electronic expansion valve 3, a rotating magnetic field is generated when a current flows through the coil 21, and the rotor 20 rotates due to electromagnetic force. The rotation of the rotor 20 also rotates the gear 19, and the rotation of the gear 19 also rotates the output shaft 18. When the output shaft 18 rotates, the internal thread (not shown) of the output shaft 18 rotates relative to the screw 17. As a result, the valve element 14 fixed to the screw 17 and the output shaft 18 advances and retreats inside the flow path 27. At this time, the advance and retreat of the valve element 14 can also be adjusted by adjusting the positive and negative amplitude of the pulse signal input to the electronic expansion valve 3.

[0022] FIG. 4 is a cross-sectional view showing the position of the valve disc during an initialization process of the railway vehicle air conditioning device according to the first embodiment of the present disclosure. In the railway vehicle air conditioning device according to the present disclosure, an initialization process is performed to determine the position of the valve disc 14 when power is supplied to the control unit 5 from the main power supply 7. As shown in FIG. 4 , when the initialization process is performed, the valve disc 14 is pressed against the valve seat 15, blocking the flow path 27. In the initialization process, a pulse signal is output in which the number of pulse signals required to tighten the electronic expansion valve 3 is increased from the upper limit opening, which is the number of pulse signals required to change the opening of the electronic expansion valve 3 from fully open to fully closed. By inputting such a pulse signal to the electronic expansion valve 3, the valve disc 14 can be reliably pressed against the valve seat 15 regardless of the position in which it was stopped during the previous operation shutdown.

[0023] 5 is a flowchart showing the initialization process of the railway vehicle air conditioner according to the first embodiment of the present disclosure. First, in step S1, when power is applied to the control unit 5 by the auxiliary power supply 8, the control unit 5 counts the number of initialization processes for fully closing the valve body and valve seat of the electronic expansion valve. In the equation shown in FIG. 5, N1 on the left side is the most recent number of power initialization processes, and N2 on the right side is the number of initialization processes up to the immediately preceding time. When power is applied, 1 is added to N2 to calculate the most recent number of power-on times.

[0024] In the event of a momentary power outage, if the auxiliary power supply 8 and the main power supply 7 are on different systems (the control unit 5 is connected to a battery), the valve disc position 14 is unlikely to become unknown, so initialization processing is not performed. This is because, even if only the main power supply 7 is cut off, the period during which the power supply is cut off is short, so the position of the valve disc 14 is unlikely to become unknown. This processing makes it possible to prevent initialization processing from being performed every time there is a momentary power outage. However, if the auxiliary power supply 8 and the main power supply 7 are on the same system, initialization processing is necessary because both the main power supply 7 and the control power supply 8 will be cut off in the event of a momentary power outage.

[0025] In step S2, an initialization process is performed for the electronic expansion valve 3. In step S3, in order to adjust the temperature inside the railway vehicle, the control unit 5 calculates the degree of superheat from the refrigerant intake temperature and evaporation temperature measured by the pressure sensor 9 and the temperature sensor 10, and outputs a pulse signal according to this degree of superheat to the electronic expansion valve 3. As a result, when the control unit 5 receives a signal to change the temperature inside the railway vehicle, it becomes possible to adjust the temperature by adjusting the opening of the electronic expansion valve 3.

[0026] In step S4, the control unit 5 counts the number of pulse signals for adjusting the opening degree of the electronic expansion valve 3 in accordance with the degree of superheat. At this time, the control unit 5 counts the number of all pulse signals required to move the electronic expansion valve 3 forward and backward.

[0027] In step S5, the number of pulse signals for the initialization process performed when the power is turned on and the number of pulse signals for adjusting the opening of the electronic expansion valve 3 are integrated to calculate an integrated value, and a signal is output if the integrated value exceeds a threshold. In step S5, if the integrated value does not exceed the threshold, the process returns to step S3, and if the integrated value exceeds the threshold, the process proceeds to step S6. At this time, this threshold may be set based on the number of pulse signals that the electronic expansion valve 3 can withstand, or may be set low in consideration of deterioration of the electronic expansion valve 3 due to vibrations of the railway vehicle.

[0028] In step S6, the notification unit 6, which has received the signal from the control unit 5, outputs an alarm. This alarm indicates that the integrated value obtained by integrating the number of pulses during the initialization process performed when the power is turned on and the number of times a pulse signal is input to adjust the opening of the electronic expansion valve 3 exceeds a threshold. The railway vehicle air conditioning device 100 according to the first embodiment of the present disclosure can detect deterioration or signs of deterioration of the electronic expansion valve by setting a threshold for the integrated value. Setting this threshold high may indicate that the electronic expansion valve has deteriorated and needs to be replaced immediately. Setting this threshold low may also indicate that there is a sign that the electronic expansion valve may be deteriorating.

[0029] Therefore, the control method for a railway vehicle air conditioning device according to the first embodiment of the present disclosure includes a step of counting the number of initialization processes that fully close the valve element 14 and the valve seat 15 of the electronic expansion valve 3, which has a valve element 14 that adjusts the opening of the flow path 27 through which the refrigerant flows in and a valve seat 15 for adjusting the distance between the valve element 14, and which is performed when power is applied to the electronic expansion valve 3, which reduces the pressure of the refrigerant flowing in from the condenser 2 to reduce its temperature; a step of counting the number of pulse signals that adjust the opening of the electronic expansion valve 3; a step of calculating an integrated value by accumulating the number of pulse signals of the initialization process that is performed when power is applied and the number of pulse signals that adjust the opening of the electronic expansion valve 3; and a step of outputting a signal to the alarm unit 6 if the integrated value exceeds a threshold value.

[0030] 6 is a schematic diagram showing the overall configuration of a railway vehicle air conditioning system according to the first embodiment of the present disclosure. As shown in Fig. 6, a railway vehicle air conditioning system 200 according to the present disclosure includes a railway vehicle air conditioner 100 and an air conditioning control device 24 that is connected to a power supply system separate from the railway vehicle air conditioner 100 and controls the railway vehicle air conditioner 100 to control the temperature inside the railway vehicle. The air conditioning control device 24 is a controller that issues instructions for, for example, temperature change, heating operation, cooling operation, ventilation operation, etc.

[0031] As described above, the railway vehicle air conditioning device 100 according to the first embodiment of the present disclosure includes a compressor 1 that compresses a refrigerant, a condenser 2 that condenses the refrigerant compressed by the compressor 1 through heat exchange, a valve element 14 that adjusts the opening of a flow path through which the refrigerant flows in, and a valve seat 15 whose amount of inflowing refrigerant is adjusted by adjusting the distance from the valve element 14. The air conditioning device 100 also includes an electronic expansion valve 3 that reduces the pressure of the refrigerant flowing in from the condenser 2 to a low temperature, an evaporator 4 that evaporates the refrigerant and exchanges heat between the evaporated refrigerant and air, and a control unit 5 that performs an initialization process to fully close the valve element 14 and the valve seat 15 of the electronic expansion valve 3 when power is applied and adjusts the opening of the electronic expansion valve 3. The control unit 5 calculates an integrated value by integrating the number of pulse signals of the initialization process that is performed when power is applied and the number of times a pulse signal is input to adjust the opening of the electronic expansion valve 3. If the integrated value exceeds a threshold value, the control unit 6 outputs a signal and issues an alarm based on the signal from the control unit 5.

[0032] According to the railway vehicle air conditioning device 100 of the present disclosure, by notifying that the number of pulse signals input exceeds a threshold before the electronic expansion valve 3 is damaged, it is possible to prevent breakdowns of the railway vehicle air conditioning device 100 during operation.

[0033] Furthermore, according to the railway vehicle air conditioning device 100 according to the first embodiment of the present disclosure, when the main power supply 7 and the auxiliary power supply 8 are separate systems, the initialization process is performed only when the control unit 5 is powered on, thereby preventing accelerated deterioration of the electronic expansion valve 3. Furthermore, the railway vehicle air conditioning device 100 according to the first embodiment of the present disclosure outputs an alarm when the number of pulse signals exceeds a threshold value, thereby making it possible to appropriately detect deterioration or signs of deterioration of the electronic expansion valve 3.

[0034] Furthermore, the railcar air conditioning device 100 according to the present disclosure may be provided with a storage unit that stores the number of pulse signals of the initialization process so that the number can be checked by a railcar safety officer. In this way, the safety officer can select an appropriate maintenance method depending on the number of times the initialization process is performed.

[0035] Furthermore, railway vehicles may experience a temporary power outage or other cause that causes the power supply to the railway vehicle air conditioning device 100 to be temporarily cut off and then restarted. The initialization process presses the valve disc 14 against the valve seat 15, which places a mechanical load on the electronic expansion valve 3. Therefore, performing the initialization process every time the vehicle is restarted accelerates deterioration of the electronic expansion valve 3. Therefore, if the main power supply 7 and the auxiliary power supply 8 are separate systems, the control unit 5 may control the system so that the initialization process is not performed when the air conditioning system is started but the control unit 5 is not started. If the control unit 5 receives power from a system different from the main power supply 7, even if a momentary power outage occurs in the main power supply 7, power is still supplied to the control unit 5, allowing the position of the valve disc to be determined. Therefore, there is no need to perform the initialization process, and the initialization process can be prevented from being performed even in such cases.

[0036] Second Embodiment In a second embodiment, the same components as those in the first embodiment of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted. Hereinafter, a railway vehicle air conditioning device 101 according to the second embodiment will be described with reference to the drawings.

[0037] FIG. 7 is a cross-sectional view showing the structure of an electronic expansion valve of a railway vehicle air conditioning system according to a second embodiment of the present disclosure. The railway vehicle air conditioning system 101 according to the second embodiment of the present disclosure includes an electronic expansion valve 3a in addition to the configuration of the electronic expansion valve of the first embodiment. As shown in FIG. 7, the electronic expansion valve 3a includes a stopper 11 in addition to the configuration of the electronic expansion valve of the first embodiment. This stopper 11 prevents contact between the valve seat 14 and the valve element 15 when the initialization process is performed. Note that although the stopper 11 is provided on the valve seat 15 in FIG. 7, it may also be provided on the tip of the valve element 14.

[0038] 8 is a cross-sectional view showing the position of the valve disc during the initialization process of the railway vehicle air conditioning system according to the second embodiment of the present disclosure. As shown in FIG. 8 , even if the initialization process moves the electronic expansion valve 3 a so as to press the valve disc 14 against the valve seat 15, the stopper 11 comes into contact with the valve disc 14, preventing the valve seat 15 from being blocked. As a result, the refrigerant flow path 27 is not completely blocked, allowing refrigerant to flow in even if, for example, the valve disc 14 stops operating due to the initialization process. Therefore, in addition to the effects of the first embodiment, the railway vehicle air conditioning system 101 according to the second embodiment of the present disclosure allows the railway vehicle air conditioning system 101 to continue operating even if the valve disc 14 stops operating due to the initialization process.

[0039] 9 is a top view showing stoppers of a railway vehicle air conditioning system according to a second embodiment of the present disclosure. As shown in FIG. 9, by arranging the stoppers 11 at intervals, a gap is created between the valve disc 14 and the valve seat 15 even when the valve disc 14 is pressed against the valve seat 15. Therefore, the refrigerant inside the flow path 27 can pass through the valve seat 15 even when an initialization process is performed. Note that while FIG. 9 shows a case where three stoppers 11 are provided on the valve seat 15, the number may be three or more.

[0040] Fig. 10 is a cross-sectional view showing another configuration of a stopper of the railway vehicle air conditioning device according to the second embodiment of the present disclosure. As shown in Fig. 10, in the railway vehicle air conditioning device 101 according to the second embodiment of the present disclosure, the stopper 25 may be provided on the output shaft 18 of the electronic expansion valve 3b. In this way, the stopper 25 is provided at a location other than the refrigerant flow path 27. Therefore, the electronic expansion valve 3b of Fig. 10 can prevent the stopper 11 from falling off due to the flow pressure of the refrigerant, in addition to the effect of the first embodiment.

[0041] 11 is a cross-sectional view showing an initialization process in the case of another configuration of the stopper of the railway vehicle air conditioner according to the second embodiment of the present disclosure. As shown in Fig. 11, when the valve element 14 of the electronic expansion valve 3b moves toward the valve seat 15 during the initialization process, the stopper 25 comes into contact with the support member 23. As a result, a gap is created between the valve element 14 and the valve seat 15, as with the electronic expansion valve 3a, and therefore the refrigerant inside the flow path 27 can pass through the valve seat 15 even when the initialization process is performed.

[0042] Embodiment 3 In embodiment 3, the same components as those in embodiment 1 of the present disclosure are designated by the same reference numerals, and descriptions of the same or corresponding parts will be omitted. Hereinafter, a railway vehicle air conditioning device 102 according to embodiment 3 will be described with reference to the drawings.

[0043] FIG. 12 is a schematic diagram showing the overall configuration of a railway vehicle air conditioning system according to a third embodiment of the present disclosure. A railway vehicle air conditioning system 102 according to the third embodiment of the present disclosure further includes a capillary tube 12, a branch pipe 13, and a distribution mechanism 26 in addition to the configuration of the first embodiment. Here, FIG. 12 does not illustrate the control unit 5, the notification unit 6, the main power supply 7, the auxiliary power supply 8, the pressure sensor 9, and the temperature sensor 10. The capillary tube 12 is a thin capillary tube with a small diameter, and reduces the pressure of the refrigerant flowing through the refrigerant circuit. The branch pipe 13 and the distribution mechanism 26 branch the refrigerant and send it to the evaporator 4.

[0044] In the railway vehicle air conditioning device 102 according to the third embodiment of the present disclosure, the capillary tube 12 is provided, and thus the refrigerant can be decompressed by the capillary tube 12 in addition to the electronic expansion valve 3. Even if the electronic expansion valve 3 fails, the refrigerant can be decompressed to a low temperature, and therefore the railway vehicle air conditioning device 102 has improved redundancy in addition to the effect of the first embodiment. In particular, with the electronic expansion valve of the present disclosure, it is important to prevent the valve body 14 and the valve seat 15 from sticking together as shown in the second embodiment, and therefore the use of the capillary tube 12 can maintain the function of the refrigerant circuit.

[0045] Fig. 13 is a schematic diagram showing another configuration of a capillary tube in a railway vehicle air conditioner according to a third embodiment of the present disclosure. In Fig. 12, the capillary tube 12 is connected to the evaporator 4, but in Fig. 13, the capillary tube 12 is connected to the electronic expansion valve 3. Even in this case, it is possible to reduce the pressure of the refrigerant and lower its temperature even if the electronic expansion valve 3 fails as shown in Fig. 12. Therefore, it is sufficient that the capillary tube 12 is provided between the condenser 2 and the evaporator 4.

[0046] The configurations described in the above embodiments are merely examples of the contents of the present disclosure, and may be combined with other known techniques. Furthermore, parts of the configurations may be omitted or modified without departing from the scope of the present disclosure.

[0047] REFERENCE SIGNS LIST 1 Compressor, 2 Condenser, 3 3a 3b Electronic expansion valve, 4 Evaporator, 5 Control unit, 6 Notification unit, 7 Main power supply, 8 Auxiliary power supply, 9 Pressure sensor, 10 Temperature sensor, 11 25 Stopper, 12 Capillary tube, 13 Branch pipe, 14 Valve body, 15 Valve seat, 16 Spring, 17 Screw, 18 Output shaft, 19 Gear, 20 Rotor, 21 Coil, 22 Holder, 23 Support member, 24 Air conditioning control device, 26 Distribution mechanism, 27 Flow path, 100 101 102 Railway vehicle air conditioning device, 200 Railway vehicle air conditioning system

Claims

1. An air conditioning system for a railway vehicle comprising: a compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the compressor through heat exchange; an electronic expansion valve that has a valve body that adjusts the opening of a flow path through which the refrigerant flows in and a valve seat whose distance from the valve body is adjusted to adjust the amount of the refrigerant flowing in, and that reduces the pressure of the refrigerant flowing in from the condenser to reduce its temperature; an evaporator that evaporates the refrigerant and exchanges heat between the evaporated refrigerant and air; and a control unit that performs an initialization process to fully close the valve body and the valve seat of the electronic expansion valve when power is turned on and adjusts the opening of the electronic expansion valve, wherein the control unit calculates an integrated value by integrating the number of pulse signals of the initialization process that is performed when power is turned on and the number of times a pulse signal is input to adjust the opening of the electronic expansion valve, and outputs a signal if the integrated value exceeds a threshold value; and an alarm unit that issues an alarm in response to the signal from the control unit.

2. The air conditioning system for railway vehicles according to claim 1, wherein the control unit does not execute the initialization process when the air conditioning system is starting up but when the control unit is not starting up.

3. A railway vehicle air conditioning system according to claim 1 or 2, wherein the electronic expansion valve has a stopper that prevents contact between the valve seat and the valve body when the initialization process is being performed.

4. An air conditioning system for a railway vehicle as described in any one of claims 1 to 3, further comprising a capillary tube provided between the condenser and the evaporator, connected in series with the electronic expansion valve, and configured to reduce the pressure of the refrigerant.

5. A railway vehicle air conditioning system comprising: an air conditioning device for railway vehicles according to any one of claims 1 to 4; and an air conditioning control device that is connected to a power supply system separate from the air conditioning device for railway vehicles and that controls the temperature inside the railway vehicle by controlling the air conditioning device for railway vehicles.

6. A control method comprising: a valve body that adjusts the opening of a flow path through which a refrigerant flows in; and a valve seat whose distance from the valve body is adjusted to adjust the amount of the refrigerant flowing in; the control method comprising the steps of: counting the number of pulse signals of an initialization process that fully closes the valve body and the valve seat of an electronic expansion valve that is carried out when power is turned on to reduce the pressure of the refrigerant flowing in from a condenser to reduce its temperature; counting the number of pulse signals that adjust the opening of the electronic expansion valve; calculating an integrated value by integrating the number of pulses during the initialization process and the number of pulse signals that adjust the opening of the electronic expansion valve; and outputting a signal to an alarm unit if the integrated value exceeds a threshold value.

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