CN115366936A - Air conditioning system for railway vehicle, control method of air conditioning system and railway vehicle - Google Patents
Air conditioning system for railway vehicle, control method of air conditioning system and railway vehicle Download PDFInfo
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- CN115366936A CN115366936A CN202110540420.9A CN202110540420A CN115366936A CN 115366936 A CN115366936 A CN 115366936A CN 202110540420 A CN202110540420 A CN 202110540420A CN 115366936 A CN115366936 A CN 115366936A
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- heat exchanger
- bypass branch
- air conditioning
- compressor
- conditioning system
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61D—BODY DETAILS OR KINDS OF RAILWAY VEHICLES
- B61D27/00—Heating, cooling, ventilating, or air-conditioning
- B61D27/0018—Air-conditioning means, i.e. combining at least two of the following ways of treating or supplying air, namely heating, cooling or ventilating
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T30/00—Transportation of goods or passengers via railways, e.g. energy recovery or reducing air resistance
Abstract
The invention provides an air conditioning system for a railway vehicle, a control method of the air conditioning system and the railway vehicle, wherein the air conditioning system comprises a main loop and a first bypass branch, a compressor, an outdoor heat exchanger, a first throttling element and an indoor heat exchanger are sequentially connected to the main loop in series, and the first bypass branch is communicated with an exhaust port of the compressor and an inlet of the indoor heat exchanger, so that part of refrigerant discharged from the compressor is discharged into the indoor heat exchanger through the first bypass branch. According to the invention, part of the refrigerant is discharged into the indoor heat exchanger through the first bypass branch instead of passing through the outdoor heat exchanger, so that the part of the high-temperature refrigerant which does not pass through the heat exchange of the outdoor heat exchanger neutralizes the temperature of the indoor heat exchanger, the cold output of the indoor heat exchanger is effectively reduced, the cold regulation range of the air conditioning unit of the railway vehicle is widened, and the refrigerating capacity of the unit is reduced when the thermal load of the railway vehicle is lower, so that the condition that the thermal load of the railway vehicle is lower is better adapted. And the risk of frequent shutdown of the compressor is avoided, and the service life of the compressor is prolonged.
Description
Technical Field
The invention relates to the field of railway vehicles, in particular to an air conditioning system for a railway vehicle, the railway vehicle and a control method of the air conditioning system.
Background
For the air conditioning unit of the railway vehicle, the indoor heat load mainly comprises a personnel heat dissipation load, a vehicle body heat transfer load, a fresh air heat load and an in-vehicle equipment heat load, and for an overground operation line, the indoor heat load is also influenced by solar radiation heat load.
In different time periods, the environment temperature outside the automobile is different, and when the environment temperature outside the automobile is low, the heat transfer load of the automobile body is small;
when the solar water heater is in spring and autumn, the solar radiation intensity is weaker, and the solar radiation heat load is smaller;
in different stations, the personnel load changes greatly, and when the number of people is small, the heat dissipation load of the personnel is small.
The rated refrigerating capacity of the air conditioning unit of the railway vehicle is generally checked according to the conditions that the outdoor temperature is high, the solar radiation intensity is high and more indoor persons exist, and the deviation between the rated refrigerating capacity and the low-load refrigerating capacity required in the actual operation is large. If the refrigerating capacity of the air conditioning unit is far larger than the heat load in the vehicle, the compressor of the air conditioning unit is started and stopped frequently, and the indoor temperature fluctuates under the influence of the minimum starting and stopping interval of the compressor.
For a railway vehicle air conditioning unit, in order to meet the refrigeration requirement under high load, the rated refrigeration capacity is generally set to be larger. For the rail vehicle, the number of the people is different in different time periods and seasons; the range of variation of the refrigerating capacity required for maintaining the temperature in the vehicle is large.
Because the rated refrigerating capacity of the air conditioning unit is set to be higher, the lower limit of the regulating range of the refrigerating capacity is also higher, and under the rated working condition, the lower limit of the regulating range of the refrigerating capacity is generally 25% of the rated refrigerating capacity.
When the heat load in the railway vehicle is low, the refrigerating capacity output of the air conditioning unit is high, the air conditioning unit and the compressor are not matched, the compressor of the air conditioning unit is started and stopped frequently, and then the temperature in the compartment of the railway vehicle fluctuates up and down to influence the comfort of passengers.
The present invention has been made in view of this situation.
Disclosure of Invention
In order to solve the above technical problems, an object of the present invention is to provide an air conditioning system for a rail vehicle, a rail vehicle and a control method of the air conditioning system, in which a refrigerant is branched by a first bypass branch, so as to reduce the cooling capacity of an indoor heat exchanger, thereby meeting a low-load condition.
In order to solve the technical problems, the invention adopts the technical scheme that:
the invention provides an air conditioning system for a railway vehicle, which comprises a main loop and a first bypass branch, wherein a compressor, an outdoor heat exchanger, a first throttling element and an indoor heat exchanger are sequentially connected to the main loop in series, and the first bypass branch is communicated with an exhaust port of the compressor and an inlet of the indoor heat exchanger, so that part of refrigerant discharged from the compressor is discharged into the indoor heat exchanger through the first bypass branch.
In the above technical solution, one end of the first bypass branch is communicated with the exhaust port of the compressor, and the other end is communicated with any pipeline between the outdoor heat exchanger and the inlet of the indoor heat exchanger;
in the above technical solution, a second throttling element is disposed on the first bypass branch, and the other end of the first bypass branch is communicated with a pipeline from the first throttling element to an inlet of the indoor heat exchanger.
In any one of the above technical solutions, the first bypass branch is provided with a first control valve for controlling the on-off of the first bypass branch.
In any of the above technical solutions, the method further includes:
a first valve port of the reversing valve is communicated with an exhaust port of the compressor, a third valve port of the reversing valve is communicated with an air inlet of the compressor, a second valve port of the reversing valve is communicated with an outlet of the indoor heat exchanger, a fourth valve port of the reversing valve is communicated with an inlet of the outdoor heat exchanger,
the reversing valve is provided with a first working position and a second working position, the first valve port is communicated with the fourth valve port, the second valve port is communicated with the third valve port when the reversing valve is in the first working position, the first valve port is communicated with the second valve port, and the third valve port is communicated with the fourth valve port when the reversing valve is in the second working position, wherein the first bypass branch can be conducted when the reversing valve is in the first working position, and the first bypass branch is kept disconnected when the reversing valve is in the second working position.
In any one of the above technical solutions, one end of the first bypass branch is communicated with the fourth valve port, or one end of the first bypass branch is communicated with a pipeline between the fourth valve port and an inlet of the outdoor heat exchanger.
In any of the above technical solutions, the method further includes: and the second bypass branch is communicated with the exhaust port of the compressor and the inlet of the outdoor heat exchanger, wherein when the reversing valve is at the first working position, the second bypass branch is kept disconnected, and when the reversing valve is at the second working position, the second bypass branch can be conducted to enable part of refrigerant discharged from the compressor to be discharged into the outdoor heat exchanger through the second bypass branch.
The invention further provides a railway vehicle, which comprises the air conditioning system for the railway vehicle.
The invention also provides a control method of the air conditioning system for the railway vehicle, which is suitable for the air conditioning system for the railway vehicle in any technical scheme and comprises the following steps:
detecting the running frequency of the compressor in the refrigeration working condition;
and when the compressor runs at the lowest frequency and the time interval from the shutdown to the restart of the compressor is less than the preset time, controlling the first bypass branch of the air conditioning system to be conducted to enter a low-frequency cold quantity control mode.
In the above technical solution, the low-frequency cold control mode includes:
detecting the ambient temperature;
and judging whether the ambient temperature reaches a preset temperature threshold value, if so, controlling a second throttling element of the first bypass branch to keep the current opening degree, otherwise, judging whether the ambient temperature is lower than the preset temperature threshold value, if so, controlling the second throttling element to increase the opening degree, otherwise, controlling the second throttling element to decrease the opening degree.
According to the air conditioning system for the railway vehicle, the first bypass branch is connected with the outdoor heat exchanger in parallel, the other part of the refrigerant is not transmitted to the first bypass branch through the outdoor heat exchanger but is discharged into the indoor heat exchanger through the first bypass branch, so that the part of the high-temperature refrigerant which is not subjected to heat exchange by the outdoor heat exchanger neutralizes the temperature of the indoor heat exchanger, compared with the condition that all the refrigerants are transmitted to the main loop, the cold output of the indoor heat exchanger is effectively reduced, the cold regulation range of the air conditioning unit for the railway vehicle is widened, and the refrigerating capacity of the air conditioning unit for the railway vehicle is reduced when the heat load of the railway vehicle is low, so that the condition that the heat load of the railway vehicle is low is better adapted. And the risk of frequent shutdown of the compressor is avoided, and the service life of the compressor is prolonged.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a schematic diagram of an air conditioning system for a rail vehicle according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating a control method of an air conditioning system according to an embodiment of the present invention.
100. An air conditioning system 1 for a rail vehicle; 101. a main loop; 102. a first bypass branch; 103. a second bypass branch;
110. a compressor; 111. an exhaust port of the compressor; 112. an air inlet of the compressor; 120. an outdoor heat exchanger; 121. an inlet of the outdoor heat exchanger; 130. a first throttling element; 140. an indoor heat exchanger; 141. an inlet of the indoor heat exchanger; 150. a second throttling element; 160. a first control valve; 170. a diverter valve; 171. a first valve port; 172. a second valve port; 173. a third valve port; 174. a fourth valve port; 180. a third throttling element.
It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but rather to illustrate it for those skilled in the art by reference to specific embodiments.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
An air conditioning system 100 for a rail vehicle and a rail vehicle according to some embodiments of the present invention will be described with reference to the drawings.
According to a first embodiment of the present invention, an air conditioning system 100 for a rail vehicle is provided, and the air conditioning system 100 for a rail vehicle includes at least a main circuit 101 and a first bypass branch 102.
Specifically, as shown in fig. 1, a compressor 110, an outdoor heat exchanger 120, a first throttling element 130, and an indoor heat exchanger 140 are connected in series to the main circuit 101 in this order. The outdoor heat exchanger 120 is a heat exchanger that is placed on a rail vehicle and can exchange heat with the environment outside the vehicle, and the indoor heat exchanger 140 is a heat exchanger that is placed on a rail vehicle and can exchange heat with the environment inside the vehicle. It is understood that the outdoor heat exchanger 120 and the indoor heat exchanger 140 are respectively provided with a fan to drive the gas to exchange heat.
The first bypass branch 102 communicates with the discharge port 111 of the compressor and the inlet 141 of the indoor heat exchanger, so that a portion of the refrigerant discharged from the compressor 110 is discharged to the indoor heat exchanger 140 through the first bypass branch 102.
The refrigeration working process of the air conditioning system is as follows:
the compressor 110 compresses the gaseous refrigerant into a high-temperature high-pressure gaseous state, wherein a part of the refrigerant is sent to the outdoor heat exchanger 120 for cooling, at this time, the outdoor heat exchanger 120 serves as a condenser, the refrigerant is cooled by the condenser and then becomes a medium-temperature high-pressure liquid refrigerant, the medium-temperature high-pressure liquid refrigerant is throttled and depressurized by the first throttling element 130 to become a low-temperature low-pressure gas-liquid mixture (more liquid), the low-temperature low-pressure gas-liquid mixture (more liquid) passes through the indoor heat exchanger 140, at this time, the indoor heat exchanger 140 serves as an evaporator, and the evaporator absorbs heat in air to vaporize the refrigerant, so that the refrigerant becomes a gaseous state, and then returns to the compressor 110 to continue to compress, and the circulation refrigeration of the main loop 101 continues.
Because the first bypass branch 102 is connected in parallel with the outdoor heat exchanger 120, another part of the refrigerant is sent to the first bypass branch 102 without passing through the outdoor heat exchanger 120 and is discharged into the indoor heat exchanger 140 through the first bypass branch 102, so that the part of the high-temperature refrigerant which does not pass through the outdoor heat exchanger 120 for heat exchange neutralizes the temperature of the indoor heat exchanger 140, compared with the whole refrigerant main loop 101, the cold output of the indoor heat exchanger 140 is effectively reduced, the cold regulation range of the rail vehicle air conditioning unit is widened, and when the heat load of the rail vehicle is low, the refrigerating capacity of the rail vehicle air conditioning unit is reduced, so that the condition that the heat load of the rail vehicle is low is better adapted. And the risk of frequent shutdown of the compressor 110 is avoided, and the service life of the compressor 110 is prolonged.
Further, in order to avoid a liquid impact on the compressor 110 caused by incomplete vaporization of the refrigerant at the side of the indoor heat exchanger 140, protect the compressor 110 from damage, and prolong the service life of the air conditioning system, a drying filter is disposed on the main circuit 101 and/or the first bypass branch 102.
For example, the first throttling element 130 may be a capillary tube, an expansion valve, or the like.
Example one
In this embodiment, on the basis of any of the foregoing embodiments, the first bypass branch 102 is further provided with one end communicating with the discharge port 111 of the compressor and the other end communicating with any pipe from the outdoor heat exchanger 120 to the inlet 141 of the indoor heat exchanger.
It is understood that the first throttling element 130 is arranged between the outdoor heat exchanger 120 and the inlet 141 of the indoor heat exchanger in series with the outdoor heat exchanger 120 and the indoor heat exchanger 140, and any pipeline communication between the other end of the first bypass branch 102 and the inlet 141 of the outdoor heat exchanger 120 and the indoor heat exchanger described in the embodiment includes the following embodiments:
implementation mode one
The other end of the first bypass branch 102 is communicated with a pipeline between the outdoor heat exchanger 120 and the first throttling element 130, so that the other part of the refrigerant which does not pass through the outdoor heat exchanger 120 but is sent to the first bypass branch 102 is throttled by the first throttling element 130 to reduce the temperature and pressure, thereby ensuring that the refrigerant flowing through the first bypass branch 102 can be completely vaporized, and avoiding the liquid impact of the compressor 110.
Second embodiment
The other end of the first bypass branch 102 is communicated with a pipeline from the first throttling element 130 to an inlet 141 of the indoor heat exchanger, so that the other part of the refrigerant which does not pass through the outdoor heat exchanger 120 but is sent to the first bypass branch 102 is not throttled by the first throttling element 130 to reduce the temperature and reduce the pressure, in order to avoid the situation that the refrigerant at the side of the indoor heat exchanger 140 is not completely vaporized to cause liquid impact on the compressor 110, the first bypass branch 102 is provided with the second throttling element 150, and the refrigerant of the first bypass branch 102 is throttled by the second throttling element 150 to reduce the temperature and reduce the pressure, thereby ensuring the reliability of the product.
Further, the air conditioning system is provided with a liquid separator, wherein the first bypass branch 102 bypasses to the rear of the first throttling element 130 and before the liquid separator.
It can be understood that, the above two embodiments make the refrigerant flowing through the first bypass branch 102 and the refrigerant of the main loop 101 join together and then flow to the indoor heat exchanger 140, so that the two portions of the refrigerants are fully mixed and exchange heat, the temperature of the mixed refrigerant is more uniform, not only the temperature of the refrigerant in the main loop 101 is effectively raised, but also the temperature of the refrigerant flowing into the indoor heat exchanger 140 is raised, the refrigerating capacity of the air conditioning unit of the rail vehicle is reduced, thereby better adapting to the condition that the heat load in the rail vehicle is lower, the condition that the temperature at the side of the indoor heat exchanger 140 is uneven and the outlet air temperature is uneven is caused, and the condition that the indoor heat exchanger 140 generates condensation due to uneven temperature is caused, the generation of condensed water at the side of the indoor heat exchanger 140 is reduced, the outlet air temperature of the air conditioning system is even and soft, and the use experience of products is improved.
Example two
The present embodiment is different from the first embodiment in that the second throttling element 150 is provided on the first bypass branch 102, the indoor heat exchanger 140 has a first flow path and a second flow path connected in parallel, the main circuit 101 includes the first flow path, and the first bypass branch 102 communicates with the second flow path. That is, in the present embodiment, the refrigerants in the main circuit 101 and the bypass branch circuit do not converge before the indoor heat exchanger 140, but flow into the indoor heat exchanger 140 through the respective first and second flow paths. The outlets of the first and second flow paths may be communicated with each other so that the refrigerant having exchanged heat with the indoor heat exchanger 140 may flow into the compressor 110 after merging, or the outlets of the first and second flow paths may be separately communicated with the compressor 110.
Furthermore, the first flow path and the second flow path are respectively provided with a plurality of pipelines, and the pipelines of the first flow path and the pipelines of the second flow path are distributed in a crossed manner.
The pipelines of the first flow path and the pipelines of the second flow path are distributed in a crossed mode, uneven temperature in the indoor heat exchanger 140 is avoided, the generation of condensed water on the side of the indoor heat exchanger 140 is reduced, the air outlet temperature of the air conditioning system is even and soft, and the use experience of products is improved.
EXAMPLE III
In this embodiment, on the basis of any one of the above embodiments, the first bypass branch 102 is provided with a first control valve 160 for controlling on/off of the first bypass branch 102.
The first control valve 160 controls the first bypass branch 102 to be conducted and blocked, so that the variable use scenes of products can be better adapted, under the refrigeration requirement under high load, the first control valve 160 controls the first bypass branch 102 to be blocked, the refrigerant can completely flow through the main loop 101, the refrigeration requirement is guaranteed, under the refrigeration requirement under low load, the first control valve 160 controls the first bypass branch 102 to be conducted, part of the refrigerant can flow through the main loop 101, the other part of the refrigerant can flow through the first bypass branch 102, and the temperature in the vehicle is suitable.
Further, the opening degree of the first control valve 160 may be adjustable, or the second throttling element 150 may be an electronic expansion valve with an adjustable opening degree.
The refrigerant distribution amounts of the main circuit 101 and the first bypass circuit are adjusted by controlling the opening degree of the first control valve 160 or the opening degree of the second throttling element 150.
In some air conditioning systems, where an indoor temperature sensor is provided, the control logic of the present embodiment is as follows:
the compressor 110 operates at the lowest frequency, and if the interval between two continuous start-stops is less than the preset time, the heat load is judged to be too small, and the low-frequency cold quantity control mode is entered.
For example, the preset time period is 3min to 10min, and preferably, the preset time period is 5min.
The second throttling element 150 is controlled to open to 50% opening.
When the temperature in the automobile is reduced, the opening degree of the bypass electronic expansion valve is increased by 10 percent, the bypass flux is increased, and the cold output of the evaporator is reduced.
When the temperature in the passenger room rises, the opening of the bypass electronic expansion valve is reduced by 10 percent, the bypass flux is reduced, and the cold output of the evaporator is increased.
The temperature in the passenger compartment is stabilized within +/-1 ℃ of the set temperature, and meanwhile, the compressor 110 is kept in a low-frequency stable operation state, so that impact on a vehicle power grid is avoided.
Example four
In this embodiment, on the basis of any of the above embodiments, the air conditioning system 100 for a rail vehicle further includes a reversing valve 170.
The direction change valve 170 is a four-way valve, a first port 171 of the direction change valve 170 communicates with the discharge port 111 of the compressor, a third port 173 of the direction change valve 170 communicates with the intake port 112 of the compressor, a second port 172 of the direction change valve 170 communicates with the outlet of the indoor heat exchanger 140, and a fourth port 174 of the direction change valve 170 communicates with the inlet 121 of the outdoor heat exchanger.
The direction valve 170 has a first operating position in which the first port 171 and the fourth port 174 are in communication, the second port 172 and the third port 173 are in communication, and a second operating position in which the direction valve 170 is in communication with the first port 171 and the second port 172, and the third port 173 and the fourth port 174, wherein the first bypass branch 102 is capable of being opened when the direction valve 170 is in the first operating position, and the first bypass branch 102 remains open when the direction valve 170 is in the second operating position.
Switching of the cooling and heating modes of the air conditioning system is achieved by the reversing valve 170, while the first bypass branch 102 is kept open in the heating mode, i.e. when the reversing valve 170 is in the second operating position, in order not to affect the operation of the heating mode.
Further, one end of the first bypass branch 102 is communicated with the fourth valve port 174, or one end of the first bypass branch 102 is communicated with a pipeline between the fourth valve port 174 and the inlet 121 of the outdoor heat exchanger.
In some embodiments, the air conditioning system 100 for a rail vehicle further includes a second bypass branch 103, and the second bypass branch 103 is communicated with the discharge port 111 of the compressor and the inlet 121 of the outdoor heat exchanger, wherein the second bypass branch 103 is kept disconnected when the direction switching valve 170 is at the first operation position, and the second bypass branch 103 is capable of conducting a portion of the refrigerant discharged from the compressor 110 to be discharged to the outdoor heat exchanger 120 through the second bypass branch 103 when the direction switching valve 170 is at the second operation position.
The second bypass branch 103 is used for a heating mode, in the heating mode, the indoor heat exchanger 140 serves as a condenser, the outdoor heat exchanger 120 serves as an evaporator, part of the refrigerant sequentially passes through the compressor 110, the indoor heat exchanger 140, the first throttling element 130 and the outdoor heat exchanger 120 in the main loop 101, and the other part of the refrigerant directly flows to the outdoor heat exchanger 120 through the second bypass branch 103 after being discharged by the compressor 110 without passing through the indoor heat exchanger 140, so that part of the refrigerant is branched by the second bypass branch 103, the amount of the refrigerant entering the indoor heat exchanger 140 is reduced, compared with the case that all the refrigerant passes through the main loop 101, the heat output of the indoor heat exchanger 140 is effectively reduced, the heat regulation range of the air conditioning unit of the rail vehicle is widened, and when the heat load of the rail vehicle is low, the heating amount of the air conditioning unit of the rail vehicle is reduced, so that the condition that the heat load of the rail vehicle is low is better adapted. And the risk of frequent shutdown of the compressor 110 is avoided, and the service life of the compressor 110 is prolonged.
In addition, the second bypass branch 103 also has a defrosting function, and after the high-temperature refrigerant which has not undergone heat exchange by the indoor heat exchanger 140 is discharged into the outdoor heat exchanger 120, the temperature of the outdoor heat exchanger 120 is effectively adjusted, so that frosting caused by too low temperature of the outdoor heat exchanger 120 is prevented, the heat exchange efficiency of the outdoor heat exchanger 120 is further ensured, and the reliability of product operation is ensured.
Further, a second bypass branch 103 is provided having one end communicating with the discharge port 111 of the compressor and the other end communicating with any pipe between the indoor heat exchanger 140 and the outlet of the outdoor heat exchanger 120. It can be understood that the first throttling element 130 is arranged between the outlets of the indoor heat exchanger 140 and the outdoor heat exchanger 120 and is connected in series with the outlets of the outdoor heat exchanger 120 and the indoor heat exchanger 140, and any pipeline communication between the other end of the second bypass branch 103 and the outlets of the indoor heat exchanger 140 and the outdoor heat exchanger 120 described in this embodiment includes the following modes:
the other end of the second bypass branch 103 is communicated with a pipeline between the indoor heat exchanger 140 and the first throttling element 130, so that the other part of the refrigerant which does not pass through the indoor heat exchanger 140 but is sent to the second bypass branch 103 is throttled by the first throttling element 130 to reduce the temperature and pressure, thereby ensuring that the refrigerant flowing through the first bypass branch 102 can be completely vaporized, and avoiding the liquid impact of the compressor 110.
Or, one end of the second bypass branch 103 is communicated with the exhaust port 111 of the compressor, and the other end is communicated with the pipeline between the first throttling element 130 and the inlet 121 of the outdoor heat exchanger, so that the other part of the refrigerant which does not pass through the indoor heat exchanger 140 but is sent to the second bypass branch 103 is not throttled by the first throttling element 130 to reduce the temperature and the pressure, in order to avoid the situation that the refrigerant at the side of the indoor heat exchanger 140 is not completely vaporized to cause liquid slugging of the compressor 110, the second bypass branch 103 is provided with the third throttling element, and the refrigerant of the second bypass branch 103 is throttled by the third throttling element to reduce the temperature and the pressure, thereby ensuring the reliability of the product.
It can be understood that, the refrigerant that flows through the second bypass branch 103 and the refrigerant of the main loop 101 are converged and then flow to the outdoor heat exchanger 120 by the two embodiments, so that the two parts of the refrigerants are fully mixed and exchange heat, the temperature of the mixed refrigerant is more uniform, the temperature of the refrigerant in the main loop 101 is effectively reduced, the temperature of the refrigerant flowing into the indoor heat exchanger 140 is reduced, the heating capacity of the air conditioning unit of the rail vehicle is reduced, the condition that the heat load in the rail vehicle is lower is better adapted, the condition that frost is condensed at the side of the outdoor heat exchanger 120 is avoided, the air outlet temperature of the air conditioning system is uniform and soft, and the use experience of products is improved.
Unlike the above embodiment, it is also possible to provide the outdoor heat exchanger 120 with a third flow path and a fourth flow path connected in parallel, the main circuit 101 including the third flow path, and the second bypass branch 103 communicating with the fourth flow path. That is, in the present embodiment, the refrigerants in the main circuit 101 and the second bypass branch 103 do not converge before the outdoor heat exchanger 120, but flow into the outdoor heat exchanger 120 through the respective third and fourth flow paths. The outlets of the third and fourth flow paths may be communicated with each other so that the refrigerant after heat exchange with the outdoor heat exchanger 120 merges and flows into the compressor 110, or the outlets of the third and fourth flow paths may be separately communicated with the compressor 110.
As shown in fig. 2, the present invention further provides a rail vehicle, including the air conditioning system 100 for a rail vehicle according to any of the above embodiments.
The first bypass branch 102 of the variable frequency air conditioning unit for the railway vehicle adopts a programmable electronic expansion valve as a bypass control device. The inlet of the electronic expansion valve is connected with the exhaust pipe of the compressor 110, and the outlet of the electronic expansion valve is connected to the main loop 101 behind the electronic expansion valve and in front of the liquid distributor.
The invention further provides a control method of the air conditioning system for the railway vehicle, which is suitable for the air conditioning system 100 for the railway vehicle in any embodiment, and comprises the following steps:
in the refrigeration working condition, detecting the running frequency of the compressor 110;
when the compressor 110 is operated at the lowest frequency and the compressor is started again from the stop for a time period less than a preset time period, the first bypass branch 102 of the air conditioning system is controlled to be turned on to enter the low frequency cooling capacity control mode.
Whether the current working condition is a low-load working condition is judged by detecting the operating frequency of the compressor and the time from the stop to the restart of the compressor, whether the low-frequency cold quantity control mode is entered or not is determined by the judging result, and the practice system is automatically controlled.
Further, the low-frequency cold-energy control mode includes:
detecting the ambient temperature;
and judging whether the ambient temperature reaches a preset temperature threshold, if so, controlling the second throttling element 150 of the first bypass branch 102 to keep the current opening, otherwise, judging whether the ambient temperature is lower than the preset temperature threshold, more specifically, judging whether the ambient temperature is lower than the minimum value of the preset temperature threshold, if so, controlling the second throttling element 150 to increase the opening, and otherwise, controlling the second throttling element 150 to decrease the opening.
In more detail, the control method of the air conditioning system for the rail vehicle includes the steps of:
it is determined whether the compressor is operating at the lowest frequency and the time interval from shutdown to restart of the compressor is less than a preset time period, for example, 5 minutes.
If not, controlling the frequency of the conventional compressor, otherwise, opening the bypass electronic expansion valve to 50%.
After the bypass electronic expansion valve is opened to 50%, detecting the ambient temperature, and determining whether the ambient temperature reaches a preset temperature threshold, for example, if the target ambient temperature is a, the preset temperature threshold is a ± 1 ℃.
If so, controlling the bypass electronic expansion valve to maintain the original opening, otherwise, judging whether the ambient temperature is lower than a lower limit value in a preset temperature threshold value, if so, controlling the opening of the bypass electronic expansion valve to increase by 10 percent, otherwise, controlling the opening of the bypass electronic expansion valve to decrease by 10 percent.
After the opening degree of the bypass electronic expansion valve is controlled to be increased by 10%, whether the opening degree of the bypass electronic expansion valve is smaller than 90% is judged, and if not, the compressor is stopped.
After the opening degree of the bypass electronic expansion valve is controlled to be reduced by 10%, whether the opening degree of the bypass electronic expansion valve is larger than 10% is judged, and if not, the bypass electronic expansion valve is closed.
The control method of the air conditioning system for the railway vehicle under the refrigeration working condition is the control method, and the control method of the heating working condition can be controlled according to the control method.
The invention has the following advantages
1. The invention can effectively reduce the lower limit value of the refrigerating output of the variable-frequency air conditioning unit of the railway vehicle, so that the variable-frequency air conditioning unit is matched with the low heat load of the railway vehicle, and the stability of the temperature in the vehicle is maintained.
2. The bypass is connected to the inlet end of the evaporator knockout drum, the heat exchange area of the evaporator can be fully utilized, the air outlet temperature of the evaporator is uniform, and the risk of condensation is avoided.
3. The refrigerant is bypassed to the inlet of the evaporator liquid separator, and the flow of the refrigerant entering the evaporator is still large, which is beneficial to the oil return of the compressor 110.
Although the present invention has been described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present invention.
Claims (10)
1. The air conditioning system for the railway vehicle is characterized by comprising a main loop and a first bypass branch, wherein a compressor, an outdoor heat exchanger, a first throttling element and an indoor heat exchanger are sequentially connected to the main loop in series, and the first bypass branch is communicated with an exhaust port of the compressor and an inlet of the indoor heat exchanger, so that part of refrigerant discharged from the compressor is discharged into the indoor heat exchanger through the first bypass branch.
2. Air conditioning system for rail vehicles according to claim 1,
one end of the first bypass branch is communicated with an exhaust port of the compressor, and the other end of the first bypass branch is communicated with any pipeline between the outdoor heat exchanger and an inlet of the indoor heat exchanger.
3. Air conditioning system for rail vehicles according to claim 2,
and a second throttling element is arranged on the first bypass branch, and the other end of the first bypass branch is communicated with a pipeline from the first throttling element to an inlet of the indoor heat exchanger.
4. Air conditioning system for rail vehicles according to any of claims 1 to 3,
and the first bypass branch is provided with a first control valve for controlling the on-off of the first bypass branch.
5. The air conditioning system for a rail vehicle according to any one of claims 1 to 3, characterized by further comprising:
a first valve port of the reversing valve is communicated with an exhaust port of the compressor, a third valve port of the reversing valve is communicated with an air inlet of the compressor, a second valve port of the reversing valve is communicated with an outlet of the indoor heat exchanger, a fourth valve port of the reversing valve is communicated with an inlet of the outdoor heat exchanger,
the reversing valve is provided with a first working position and a second working position, the first valve port and the fourth valve port are communicated, the second valve port and the third valve port are communicated when the reversing valve is in the first working position, the first valve port and the second valve port are communicated, and the third valve port and the fourth valve port are communicated when the reversing valve is in the second working position, wherein the first bypass branch can be conducted when the reversing valve is in the first working position, and the first bypass branch is kept disconnected when the reversing valve is in the second working position.
6. Air conditioning system for rail vehicles according to claim 5,
one end of the first bypass branch is communicated with the fourth valve port, or one end of the first bypass branch is communicated with a pipeline between the fourth valve port and an inlet of the outdoor heat exchanger.
7. The air conditioning system for a rail vehicle of claim 5, further comprising:
and the second bypass branch is communicated with the exhaust port of the compressor and the inlet of the outdoor heat exchanger, when the reversing valve is at the first working position, the second bypass branch is kept disconnected, and when the reversing valve is at the second working position, the second bypass branch can be conducted to enable part of refrigerant discharged from the compressor to be discharged into the outdoor heat exchanger through the second bypass branch.
8. A rail vehicle, characterized in that it comprises an air conditioning system for rail vehicles according to any one of claims 1 to 7.
9. A control method of an air conditioning system for a railway vehicle, which is applied to the air conditioning system for a railway vehicle of any one of claims 1 to 7, characterized by comprising the steps of:
detecting the running frequency of the compressor under the refrigeration working condition;
and when the compressor runs at the lowest frequency and the time interval from the shutdown to the restart of the compressor is less than the preset time, controlling the first bypass branch of the air conditioning system to be conducted to enter a low-frequency cold quantity control mode.
10. The control method of an air conditioning system for a rail vehicle according to claim 9, wherein the low frequency cooling control mode includes:
detecting the ambient temperature;
and judging whether the ambient temperature reaches a preset temperature threshold value, if so, controlling a second throttling element of the first bypass branch to keep the current opening degree, otherwise, judging whether the ambient temperature is lower than the preset temperature threshold value, if so, controlling the second throttling element to increase the opening degree, otherwise, controlling the second throttling element to decrease the opening degree.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110540420.9A CN115366936A (en) | 2021-05-18 | 2021-05-18 | Air conditioning system for railway vehicle, control method of air conditioning system and railway vehicle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110540420.9A CN115366936A (en) | 2021-05-18 | 2021-05-18 | Air conditioning system for railway vehicle, control method of air conditioning system and railway vehicle |
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| Publication Number | Publication Date |
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| CN115366936A true CN115366936A (en) | 2022-11-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202110540420.9A Pending CN115366936A (en) | 2021-05-18 | 2021-05-18 | Air conditioning system for railway vehicle, control method of air conditioning system and railway vehicle |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116620339A (en) * | 2023-04-18 | 2023-08-22 | 中车青岛四方机车车辆股份有限公司 | Rail vehicle and low vacuum rail vehicle system |
-
2021
- 2021-05-18 CN CN202110540420.9A patent/CN115366936A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116620339A (en) * | 2023-04-18 | 2023-08-22 | 中车青岛四方机车车辆股份有限公司 | Rail vehicle and low vacuum rail vehicle system |
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