Rail vehicle air conditioning units

Abstract

The present invention discloses a rail vehicle air-conditioning unit, which belongs to the technical field of rail vehicle air-conditioning systems, and includes a refrigerant circuit, a condensing fan located in a condensing chamber, and an air supply fan located in an evaporating chamber. The refrigerant circuit includes a compressor, an exhaust check valve, a condenser, a liquid pipe solenoid valve, an electronic expansion valve, an evaporator, a low-pressure pressure sensor, and a return air solenoid valve. The key point is that the refrigerant in the refrigerant circuit is R290; the air-conditioning unit performs an evacuation cycle operation before each shutdown and power outage to store the refrigerant in the condenser; each time the compressor stops running, the liquid pipe solenoid valve and the return air solenoid valve are closed at the same time. The beneficial effects of the present invention are: 1. The refrigerant uses R290, which greatly reduces the pollution to the atmosphere. At the same time, with the advancement of the EU F-Gas requirements, the problem of subsequent refrigerant replacement is avoided; 2. After the air-conditioning unit is shut down, the condenser can be stored in the condenser to prevent the refrigerant from leaking in the evaporating chamber, thereby ensuring the safety of the unit.

Description

Technical Field

[0001] The present invention belongs to the technical field of rail vehicle air-conditioning systems, and in particular relates to an air-conditioning unit for a rail vehicle. Background Art

[0002] To meet the demands of economic development, resource conservation, and ecological protection, refrigerants must be environmentally friendly and energy-efficient. Therefore, refrigerants such as R134a and R407C currently used in rail vehicle air conditioning units will be gradually phased out, with R513A serving only as a short-term transitional refrigerant. R290, with a GWP of 3, not only meets cooling performance requirements but also complies with relevant regulations.

[0003] While R290 refrigerant is environmentally friendly, boasts a higher latent heat of vaporization, a lower molecular weight, higher operating pressure and density, and a smaller refrigerant charge than R513A, its safety rating is A3, making it flammable, and safety issues need to be addressed. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a rail vehicle air-conditioning unit, which uses R290 as refrigerant. The air-conditioning unit performs an evacuation cycle operation before each shutdown and power outage to store the refrigerant in the condenser, and each time the compressor stops running, the liquid pipe solenoid valve and the return air solenoid valve are closed at the same time to avoid refrigerant leakage in the evaporation chamber, thereby solving the safety problem of the refrigerant.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a rail vehicle air-conditioning unit, including a refrigerant circuit, a condensing fan located in the condensing chamber and a blower located in the evaporating chamber, the refrigerant circuit includes a compressor, an exhaust check valve, a condenser, a liquid pipe solenoid valve, an electronic expansion valve, an evaporator, a low-pressure pressure sensor and a return air solenoid valve. The key is that the refrigerant in the refrigerant circuit is R290; the air-conditioning unit performs an evacuation cycle operation before each shutdown and power outage to store the refrigerant in the condenser; each time the compressor stops running, the liquid pipe solenoid valve and the return air solenoid valve are closed at the same time.

[0006] Furthermore, the pump-down cycle operation includes the following steps: when the air-conditioning unit receives a shutdown command, the liquid pipe solenoid valve is first closed, and then when the low-pressure pressure sensor detects that the pressure is lower than 0.1MPa, the liquid pipe solenoid valve has been closed and lasts for 10s, or the low-pressure pressure switch is activated, the compressor stops.

[0007] Furthermore, after the compressor stops: if the compressor stops in automatic mode, the opening of the electronic expansion valve is restored to the default opening when the compressor is turned on; if the compressor stops in manual mode, the opening of the electronic expansion valve is restored to the default opening when the air-conditioning controller is normal or the control circuit has power, otherwise the current opening is maintained.

[0008] Furthermore, when it is detected that the air-conditioning unit needs to operate in cooling mode or heating mode, the liquid pipe solenoid valve and the return air solenoid valve are opened at the same time and a pressure switch fault detection is performed after 15 seconds. When the detection is normal, the compressor is allowed to start.

[0009] Furthermore, when the propane sensor in the condensing chamber detects a refrigerant leak, the air conditioning unit performs the following steps:

[0010] Step a: Detect the current operating mode of the air-conditioning unit. If it is in cooling mode, execute step d; if it is in heating mode, execute step b.

[0011] Step b, the air supply fan and the condensing fan are running, and the liquid pipe solenoid valve and the return air solenoid valve are open;

[0012] Step c: The compressor starts running 5 seconds after the liquid pipe solenoid valve and the return air solenoid valve are opened;

[0013] Step d, check whether there is a refrigerant leakage alarm. If so, close the fresh air valve and liquid pipe solenoid valve and execute step e; otherwise, keep the compressor running;

[0014] Step e: Check whether the low-pressure switch is actuated. If the low-pressure switch is actuated or the low-pressure switch is inactive for 20 seconds, the compressor stops, the return air solenoid valve closes, and the blower and condenser fan keep running, and step f is executed.

[0015] Step f: Check whether there is a refrigerant leakage alarm. If so, keep the compressor stopped, the return air solenoid valve closed, and the condensing fan and the supply fan running. Otherwise, the air conditioning unit is shut down.

[0016] Furthermore, the condensing fan is an explosion-proof fan.

[0017] Furthermore, the compressor and the condensing fan are located in the middle of the condensing chamber, and condensers are provided on both sides of the middle of the condensing chamber.

[0018] Furthermore, a return air valve and a control panel are provided in the middle of the evaporation chamber, and a fresh air valve, a blower, an evaporator and an electric heater are provided on both sides of the middle of the evaporation chamber.

[0019] Furthermore, all components of the refrigerant circuit except the evaporator are located in the condensing chamber, and the welding joints between the evaporator and the supporting pipelines are located in the condensing chamber.

[0020] Furthermore, propane sensors are provided in both the evaporation chamber and the condensation chamber.

[0021] The beneficial effects of the present invention are: 1. The refrigerant uses R290, which greatly reduces pollution to the atmosphere. At the same time, with the advancement of EU F-Gas requirements, the problem of subsequent refrigerant replacement is avoided; 2. After the air-conditioning unit is shut down, the condensing agent can be stored in the condenser to prevent the refrigerant from leaking in the evaporation chamber, thereby ensuring the safety of the unit.

[0022] The present invention will be described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of the air-conditioning unit in the present invention;

[0024] Figure 2 It is a schematic diagram of the principle of the air-conditioning unit in the present invention;

[0025] Figure 3 This is a control flow chart of the air conditioning unit when refrigerant leaks in the present invention.

[0026] In the attached figure, 1. compressor, 2. high-pressure pressure switch, 3. exhaust check valve, 4. high-pressure pressure sensor, 5. condenser, 6. condensing fan, 7. low-pressure pressure switch, 8. drying filter, 9. sight glass, 10. needle valve, 11. liquid pipe solenoid valve, 12. electronic expansion valve, 13. evaporator, 14. electric heater, 15. blower, 16. low-pressure pressure sensor, 17. bypass solenoid valve, 18. return air solenoid valve, 19. return air valve, 20. control panel, 21. fresh air valve, a. condensing chamber, b. evaporating chamber. DETAILED DESCRIPTION

[0027] See attached Figure 1 and 2 The present invention provides a rail vehicle air-conditioning unit, comprising a box body having a condensing chamber a and an evaporating chamber b, a refrigerant circuit arranged in the box body, a condensing fan 6 located in the condensing chamber a, and a blower 15 located in the evaporating chamber b.

[0028] The refrigerant circuit includes a compressor 1, a high-pressure switch 2, an exhaust check valve 3, a high-pressure pressure sensor 4, a condenser 5, a low-pressure switch 7, a filter drier 8, a sight glass 9, a needle valve 10, a liquid line solenoid valve 11, an electronic expansion valve 12, an evaporator 13, a low-pressure sensor 16, a bypass solenoid valve 17, a return air solenoid valve 18, and associated piping. The refrigerant in the refrigerant circuit is R290. All components of the refrigerant circuit, except the evaporator 13, are located within the condensing chamber a. The welded joints between the evaporator 13 and the associated piping are also located within this chamber a.

[0029] The return air solenoid valve 18 is disposed between the refrigerant outlet of the evaporator 13 and the refrigerant inlet of the compressor 1 to prevent the refrigerant in the compressor 1 from flowing back into the evaporator 13 .

[0030] To reduce safety risks, in the above-mentioned refrigerant circuit: the weld of the evaporator 13 is designed in the condensing chamber a to ensure that the evaporating chamber a located in the indoor part is completely filled with seamless copper tubes to avoid indoor leakage. Air-conditioning system components, such as high and low pressure switches, high and low pressure sensors, electronic expansion valve 12, solenoid valves, etc. are all installed in the condensing chamber a, and explosion-proof components are used to avoid explosions in the event of outdoor leakage. The condenser uses a microchannel heat exchanger to reduce the R290 charge to reduce risks. A solenoid valve is added between the outlet of the evaporator 13 and the return air port of the compressor to prevent the R290 in the compressor chamber from flowing back into the evaporator to reduce indoor risks.

[0031] Compressor 1 and condensing fan 6 are located in the center of condensing chamber a, with condensers 5 installed on both sides of the center. A return air valve 19 and control panel 20 are located in the center of evaporating chamber b. Fresh air valve 21, blower 15, evaporator 13, and electric heater 14 are located on both sides of the center of evaporating chamber b. Propane sensors are installed in both evaporating chamber b and condensing chamber a to monitor leaks within the air conditioning unit in real time.

[0032] The condenser fan uses an explosion-proof fan to ensure timely ventilation when a leak is detected to reduce the concentration of R290. The control panel and electric heater, which pose an ignition source risk, are installed inside the indoor cavity to avoid the risk of contact with R290 gas.

[0033] The present invention reduces the risks that may occur due to the use of R290 refrigerant through the following specific control measures.

[0034] 1.1 The air conditioning unit performs a pump-down cycle before each shutdown to store refrigerant in the condenser 5. When the air conditioning unit is operating normally before shutdown, the liquid pipe solenoid valve 11 and the return air solenoid valve 18 are closed simultaneously each time the compressor 1 stops running. Even though not all the refrigerant can be pumped into the condenser 5 as in a pump-down cycle, closing the solenoid valves can ensure that the refrigerant in the condenser 5 and the pipeline will not flow into the evaporator 13.

[0035] The pump-down cycle operation specifically includes the following steps: when the air-conditioning unit receives a shutdown command, the liquid pipe solenoid valve 11 is first closed, and then when the low-pressure pressure sensor 16 detects that the pressure is lower than 0.1 MPa, the liquid pipe solenoid valve 11 has been closed and maintained for 10 seconds, or the low-pressure pressure switch 7 is actuated, the compressor 1 is shut down.

[0036] 1.2 Control of the opening of the electronic expansion valve 12 after the compressor 1 stops:

[0037] If the compressor is shut down in automatic mode, the opening of the electronic expansion valve 12 is restored to the default opening when the compressor is turned on, in preparation for the next quick start;

[0038] If the compressor is shut down in manual mode, in order to quickly start the next time, the opening of the electronic expansion valve 12 will be restored to the default opening at startup when the air-conditioning controller is normal or the control circuit has power, otherwise the current opening will be maintained (that is, when the air-conditioning controller fails or the control circuit has no power, the electronic expansion valve maintains the current opening without adjustment).

[0039] 1.3 When it is detected that the air conditioning unit needs to operate in cooling mode or heating mode, the liquid pipe solenoid valve 11 and the return air solenoid valve 18 are opened at the same time and a pressure switch fault detection is performed after 15 seconds. If the detection is normal, compressor 1 is allowed to start to reduce the risk of explosion caused by excessive low pressure during compressor startup and repeated startup causing compressor overheating.

[0040] 1.4 As attached Figure 3 As shown, when the propane sensor in the condensing chamber a detects refrigerant leakage, the air conditioning unit performs the following steps.

[0041] Step a: Detect the current operating mode of the air-conditioning unit. If it is running in cooling mode, directly adjust it to the highest cooling level cooling mode and execute step d after the blower 15 and the condensing fan 6 are running at high speed. If it is running in heating mode, execute step b.

[0042] This step ensures that the cooling mode is running so that the pump-down cycle can be performed to seal all the refrigerant into the condenser.

[0043] Step b: The blower 15 and the condensing blower 6 are operated at high speed, and then the liquid pipe solenoid valve 11 and the return air solenoid valve 18 are opened.

[0044] The concentration of the leaked refrigerant can be diluted by running the blower 15 and the condensing fan 6 at high speed, and the liquid pipe solenoid valve 11 and the return air solenoid valve 18 are opened to ensure that the compressor 1 can start normally.

[0045] Step c: After the liquid line solenoid valve 11 and the return air solenoid valve 18 are opened for 5 seconds, the compressor 1 is operated at high speed. At this time, the air conditioning unit is operating in the highest level cooling mode. This step ensures that the liquid line solenoid valve 11 and the return air solenoid valve 18 are opened before starting the compressor 1.

[0046] Step d: Check for refrigerant leaks (at a frequency of 1 second). If so, close fresh air valve 21 and liquid pipe solenoid valve 11, report to the backend, and proceed to step e. Otherwise, maintain high-speed operation of compressor 1. This step closes fresh air valve 21 to prevent refrigerant from entering the vehicle through the fresh air inlet and simultaneously closes liquid pipe solenoid valve 11 to pump down the refrigeration system.

[0047] Step e: Check whether low-pressure switch 7 is actuated. If it is detected that low-pressure switch 7 is actuated or if it is inactive for 20 seconds, compressor 1 stops, return air solenoid valve 18 closes, and blower 15 and condenser fan 6 maintain high-speed operation. Then, step f is executed. This step is a pump-down cycle operation in cooling mode, in which compressor 1 is stopped according to the low-pressure level of the refrigeration system.

[0048] Step f: Check for refrigerant leakage alarms (at a frequency of 1 second). If so, compressor 1 is stopped, return air solenoid valve 18 is closed, and condensing fan 6 and blower 15 continue to operate at high speed. Otherwise, the air conditioning unit shuts down. After the pump-down cycle is complete, this step dilutes the leaked refrigerant by operating blower 15 and condensing fan 6 at high speed until the refrigerant leakage alarm ceases and the air conditioning unit shuts down.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solutions of the present invention. They should all be included in the scope of the technical solutions claimed for protection by the present invention.

Claims

1. A rail vehicle air conditioning unit, comprising a refrigerant circuit, a condensing fan (6) located in a condensing chamber (a), and a blower (15) located in an evaporating chamber (b), wherein the refrigerant circuit comprises a compressor (1), an exhaust check valve (3), a condenser (5), a liquid pipe solenoid valve (11), an electronic expansion valve (12), an evaporator (13), a low-pressure pressure sensor (16), and a return air solenoid valve (18), and is characterized in that: The refrigerant in the refrigerant circuit is R290; the return air solenoid valve (18) is arranged between the refrigerant outlet of the evaporator (13) and the refrigerant inlet of the compressor (1); a low-pressure switch (7) is provided on the air inlet side of the compressor (1) in the refrigerant circuit; The air conditioning unit performs a pump-down cycle operation before each shutdown to store the refrigerant in the condenser (5); Each time the compressor (1) stops running, the liquid pipe solenoid valve (11) and the return air solenoid valve (18) are closed simultaneously; When the propane sensor in the condensing chamber (a) detects a refrigerant leak, the air conditioning unit performs the following steps: Step a: Detect the current operating mode of the air-conditioning unit. If it is in cooling mode, execute step d; if it is in heating mode, execute step b. Step b, the air supply fan (15) and the condensing fan (6) are running, then the liquid pipe solenoid valve (11) and the return air solenoid valve (18) are opened, and then step c is performed; Step c, after the liquid pipe solenoid valve (11) and the return air solenoid valve (18) are opened for 5 seconds, the compressor (1) is operated, and then step d is performed; Step d, detecting whether there is a refrigerant leakage alarm, if so, closing the fresh air valve (21) and the liquid pipe solenoid valve (11) and executing step e, otherwise keeping the compressor (1) running; Step e, detecting whether the low-pressure switch (7) is actuated. If the low-pressure switch (7) is actuated or the low-pressure switch (7) is not actuated and remains actuated for 20 seconds, the compressor (1) stops running, the return air solenoid valve (18) is closed, and the blower (15) and the condensing fan (6) remain in operation and step f is executed; Step f: Check whether there is a refrigerant leakage alarm. If so, the compressor (1) is stopped, the return air solenoid valve (18) is closed, and the condensing fan (6) and the air supply fan (15) are in operation. Otherwise, the air conditioning unit is shut down.

2. The rail vehicle air conditioning unit according to claim 1, characterized in that: The pump-down cycle operation comprises the following steps: When the air-conditioning unit receives a shutdown command, it first closes the liquid pipe solenoid valve (11), and then when the low-pressure pressure sensor (16) detects that the pressure is lower than 0.1 MPa, the liquid pipe solenoid valve (11) has been closed for 10 seconds, or the low-pressure pressure switch (7) is actuated, the compressor (1) stops.

3. The rail vehicle air conditioning unit according to claim 1, characterized in that: After the compressor stops: If the compressor is stopped in automatic mode, the opening of the electronic expansion valve (12) is restored to the default opening when the compressor is turned on; If the compressor is stopped in manual mode, the opening of the electronic expansion valve (12) is restored to the default opening when the air conditioner controller is normal or the control circuit has power, otherwise the current opening is maintained.

4. The rail vehicle air conditioning unit according to claim 1, characterized in that: When it is detected that the air conditioning unit needs to operate in cooling mode or heating mode, the liquid pipe solenoid valve (11) and the return air solenoid valve (18) are opened at the same time and a pressure switch fault detection is performed after 15 seconds. When the detection is normal, the compressor (1) is allowed to start.

5. The rail vehicle air conditioning unit according to claim 1, characterized in that: The condensing fan (6) is an explosion-proof fan.

6. The rail vehicle air conditioning unit according to any one of claims 1 to 5, characterized in that: The compressor (1) and the condensing fan (6) are located in the middle of the condensing chamber (a), and condensers (5) are provided on both sides of the middle of the condensing chamber (a).

7. The rail vehicle air conditioning unit according to any one of claims 1 to 5, characterized in that: A return air valve (19) and a control panel (20) are provided in the middle of the evaporation chamber (b), and a fresh air valve (21), a blower (15), an evaporator (13), and an electric heater (14) are provided on both sides of the middle of the evaporation chamber (b).

8. The rail vehicle air conditioning unit according to any one of claims 1 to 5, characterized in that: All components of the refrigerant circuit except the evaporator (13) are located in the condensing chamber (a), and the welding joint between the evaporator (13) and the matching pipeline is located in the condensing chamber (a).

9. The rail vehicle air conditioning unit according to any one of claims 1 to 5, characterized in that: Propane sensors are provided in both the evaporation chamber (b) and the condensation chamber (a).

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