Patent Grant
11001278
This application claims the benefit of FR Application No. 17 58158, filed Sep. 5, 2017, which is incorporated herein by reference in its entirety.
The present invention relates to a process for supervising an air conditioning system of a railway vehicle. The invention also relatives to a railway vehicle comprising an air conditioning system implementing this process.
In a known manner, modern railway vehicles intended to carry passengers are generally equipped with air conditioning systems in order to improve traveler comfort. These air conditioning systems, also known under the name HVAC, which stands for “Heating, Ventilation and Air Conditioning”, are typically based on a thermodynamic refrigeration cycle using a refrigerant.
US 2007/0163276 A1 discloses a process for evaluating the quantity of refrigerant circulating in an air conditioning system. The system traditionally includes an evaporator, a condenser, a compressor and an expander. This process is of the semi-empirical type, i.e., one uses data adjusted based on experimental results in order to simplify the calculations. Typically, paragraph [0034] of US 2007/0163276 A1 explains that certain parameters, in particular parameter kch, are calculated from an experimental model. This experimental model is established by varying, over several cycles, the mass of the refrigerant from 60 to 140% relative to a nominal mass, the air flow of the evaporator, also from 60 to 140% relative to a nominal air flow, the air flow of the condenser, from 32% to 100% of its nominal value, etc. It is therefore understood that this experimental model must be established for each air conditioner line, which is particularly costly.
US 2011/0036104 A1 discloses a substantially equivalent process, in which certain constants are established, in advance, from experimental results (see in particular paragraph [0168]).
The invention aims to resolve these drawbacks by proposing a new monitoring process allowing the real-time calculation of the mass of refrigerant contained in the system, without performing any test beforehand. Maintenance operations may therefore be planned intelligently, for example when the loss of mass exceeds a certain threshold, indicating the presence of a leak.
To that end, the invention relates to a process for monitoring an air conditioning system of a railway vehicle, this air conditioning system including several components, which include a compressor, a condenser, an evaporator, an expander and a refrigerant circuit, this air conditioning system being intended to provide air conditioning for a zone located inside the railway vehicle. This process comprises the following steps:
Owing to the invention, by calculating, in real-time, the mass of refrigerant present in the air conditioning system from physical properties measured during its operation, one has real-time information on the health of the air conditioning system. Additionally, the process is carried out noninvasively, during the operation of the system. This means that it is not necessary to open or disassemble the system to carry out the measurements of the physical properties. On the contrary, the sensors are integrated into the system. There is therefore no need to interrupt the refrigerant cycle, for example, or to deposit the system and make it unavailable in order to carry out the evaluation.
The process allows a quick detection of a loss of refrigerant mass, and therefore the presence of a leak. The calculation of the refrigerant mass does not require any test or other prior experimentation and is transposable to any type of air conditioning system, i.e., irrespective of the size of the system. Furthermore, maintenance operations may take place only when a loss of mass is detected, i.e., a leak. Thus, the maintenance cost of the air conditioning system is reduced, and the risk of untimely failure of the air conditioning system is limited.
According to advantageous but optional aspects of the invention, such a process may incorporate one or more of the following features, considered alone or according to any technically allowable combination:
According to another aspect, the invention relates to a railway vehicle comprising an air conditioning system for supplying air conditioning to a zone located inside the railway vehicle, this air conditioning system including several components, which include a compressor, a condenser, an evaporator, an expander and a refrigerant circuit, the air conditioning system further including sensors for measuring physical properties relative to the refrigerant after the air conditioning system is turned on. According to the invention, the railway vehicle comprises an electronic calculator intended to control the air conditioning system and programmed to carry out steps consisting of:
The invention will be better understood and other advantages thereof will appear more clearly in light of the following description of one embodiment of a monitoring process and an air conditioning system for a railway vehicle, provided solely as a non-limiting example and done in reference to the appended drawings.
In a known manner, the vehicle 3 is suitable for rolling on a railroad track 4 and to that end comprises railway wheels and at least one engine capable of propelling the vehicle 2.
The vehicle 3 comprises one or several railway cars 6 intended to receive passengers. Each car 6 is equipped with an air conditioning system 8 that is configured to provide air conditioning to a space 10 inside the car 6. “Air condition” here means that the system 8 is capable of bringing the temperature of the air inside the space 10 to a predefined setpoint temperature.
In the illustrated example, each air conditioning system 8 is received in a dedicated equipment cabinet, here housed on the roof of the corresponding car 6. Other arrangements are, however, possible.
In this example, the space 10, also called zone 10, takes up all of the useful space of the car 6.
Alternatively, several air conditioning systems 8 can be associated with a same car 6, to provide air conditioning to several separate zones 10 within a same car 6, these zones 10 for example being associated with separate compartments of the car 6. In this case, the systems 8 can operate independently.
According to still another alternative, several systems 8 can be used to air condition a same zone 10. In this case, they operate jointly.
The compressor 12 comprises an electric motor that drives a mechanical member suitable for compressing the refrigerant. The compressor 12 is therefore suitable for supplying mechanical work to the refrigerant. The compressor 12 is for example a piston compressor, or a rotary compressor, or a compressor according to any other appropriate technology. The motor of the compressor 12 here is supplied with electricity by a power source outside the system 8, for example using an electricity supply system of the vehicle 3.
Here, the circuit 20 is formed by several pipes connected to the components of the system 8 sealably. A first pipe connects an outlet of the compressor 12 to an inlet of the condenser 14. A second pipe connects the outlet of the condenser 14 to an inlet of the expander 18. A third pipe connects an outlet of the expander 18 to an inlet of the evaporator 16. A fourth pipe connects an outlet of the evaporator 16 to an inlet of the compressor 12. The circuit 20 comprises a refrigerant, which circulates within the circuit 20.
The system 8 also includes an outside air inlet opening and a hot air outlet, not illustrated, which both emerge outside the vehicle 3.
The system 8 further includes a cool air outlet, not illustrated, which emerges inside the car 6 to supply cool air intended to provide air conditioning to the space 10. For example, the car 6 includes an air distribution circuit including pipes connected to said cool air outlet and emerging in the space 10 through aeration nozzles.
The system 8 here is suitable for operating according to a thermodynamic cooling cycle, for example according to a steam compression cycle of a refrigerant, known in itself.
In a normal operation of the system 8, the fluid flows in the circuit 20 in the circulation direction illustrated by arrow F, passing from the outlet of the compressor 12 toward the condenser 14, then toward the expansion expander 18 and the evaporator 16 before returning to the inlet of the compressor 12.
The air coming from outside the vehicle 3 forms an incoming air flow that circulates at the evaporator 16, outside the latter, between the outside air inlet and the cool air outlet. When the system 8 is operating and the refrigerant circulates in the evaporator 16, the fluid changes state and evaporates while absorbing a first quantity of heat QL during each cycle, which cools the incoming air flow during its passage at the evaporator 16, in particular owing to the heat exchanger. This air thus cooled is conveyed toward the inside of the car 6, via the cool air outlet, to provide air conditioning to the space 10.
The refrigerant next circulates to the compressor 12, then toward the condenser 14, where it again changes state, and condenses while giving off a second quantity of heat QH toward the outside during each cycle, which heats the outgoing air flow during its passage at the condenser 14. The air thus heated is discharged toward the outside of the vehicle 3, via a hot air outlet.
Advantageously, the system 8 includes monitoring means, which aim to conduct a real-time measurement of the health of the system 8, requiring a maintenance operation.
The system 8 also includes an electronic calculator 40 programmed to control system 8 and monitor the health of the system 8. This calculator 40 is for example on board the system 8, here inside the equipment cabinet in which the system 8 is housed.
The calculator 40 illustrated schematically in
Advantageously, and as shown in
The medium 44 comprises instructions executable to carry out the process according to the invention, in particular in order to monitor the operation of the system 8. These instructions are executed by the logic unit 42.
The input interface 46 here is configured to receive measurement signals coming from various aforementioned sensors equipping the system 8. For example, the input interface 46 is connected to these sensors using wired connections and/or wireless data connections.
The output interface 48 is in particular configured to send data representative of the health of the system 8, such as a signal representative of the health of the system 8, or even an alert signal indicating a failure requiring an intervention. This data is for example sent to a remote computer server, for example installed within a maintenance center of the vehicle 3. The sending is done using a telecommunications link, such as a radio link, or via the Internet and/or a wireless telephony network and/or a satellite link. The data may also be stored within the medium 44 and/or within a computer on board the vehicle 3.
Thus, in this example, the sensors and the calculator 40 together form the aforementioned monitoring means.
An example operation of the monitoring process is now described. It is considered for the example that the air conditioning system is not new, i.e., that the process is carried out after the commissioning of the air conditioning system 8.
During a step a), the physical properties relative to the refrigerant are measured. Typically, the following physical properties are measured:
To that end, the system 8 comprises a first pressure sensor 22 and a second pressure sensor 24, suitable for measuring the pressures Psuc and Pdis, respectively. The system 8 also comprises a temperature sensor 26 for measuring the temperature “Tcond,in” of the refrigerant at the inlet of the condenser 14, a temperature sensor 28 for measuring the temperature “Tcond,out” of the refrigerant leaving the condenser 14, a temperature sensor 30 for measuring the temperature “Tevap,in” of the refrigerant at the inlet of the evaporator 16, a temperature sensor 32 for measuring the temperature “Tevap,out” of the refrigerant at the outlet of the evaporator 16, a temperature sensor 34 for measuring the temperature “Tsuc” of the refrigerant at the inlet of the compressor 12 and a temperature sensor 36 for measuring the temperature “Tdis” of the refrigerant at the outlet of the compressor 12.
Alternatively, one of the temperature sensors 32 and 34 can be omitted. Indeed, in the cases where the system 8 occupies a smaller volume and the evaporator 16 is close to the inlet of the compressor 12, the temperature variation of the refrigerant between the outlet of the evaporator 16 and the inlet of the compressor 12 is negligible, such that only one of the temperature sensors 32 and 34 is sufficient to measure the temperature of the refrigerant in these two locations. In other words, the temperature “Tsuc” and the temperature “Tevap,out” are then measured by a same temperature sensor 32 or 34.
The same is true for the temperature sensors 26 and 36, one of which can be omitted. In other words, the temperature “Tdis” and the temperature “Tcond,in” are then measured by a same temperature sensor 26 or 36.
During a subsequent step b), thermodynamic properties are calculated from the physical properties measured during step a). Typically, the thermodynamic properties include:
In the definitions above and below, the notation f( . . . ) generically indicates that a property depends on one or several measured and/or physical properties, according to a predefined relationship. This predefined relationship is not necessarily the same for all definitions, although the same notation f( . . . ) is used here. The formulas for calculating thermodynamic properties are well known from the literature on the subject, which is why they are not recalled in this document.
The calculations in this step b) are done automatically by the calculator 40.
During a later step c), one calculates, from the thermodynamic properties calculated during step b), the density, optionally averaged, of the refrigerant inside each component of the air conditioning system.
More specifically, the calculator 40 in particular calculates:
Optionally, the air conditioning system 8 also includes an accumulator (not shown) arranged between the condenser 14 and the detector 18. The accumulator makes it possible to store part of the refrigerant if all of the refrigerant is not used in the cooling cycle. In this case, the calculator is also used to calculate the average density of refrigerant inside the accumulator:
During a later step d), manufacturer data is used to calculate the passage volume of the refrigerant inside each component of the air conditioning system, i.e.:
The manufacturer data typically includes the dimensions of each component of the air conditioning system (length, width, height, section, etc.). This data is known, and will therefore simply be stored as input parameters in the information recording medium 44 of the calculator, i.e., in the memory.
The arrows show the order of the phase transformations. Between points A and B, the fluid undergoes an expansion in the expander 18 and goes from the liquid state to the diphasic state. Between points B and C, the fluid passes through the evaporator 16 and goes from the diphasic state to the vapor state (a single phase change). Thus, the evaporator includes a segment 16a, along which the fluid is in the diphasic state, and a segment 16b, along which the fluid is in the vapor state. Between points C and D, the fluid is compressed by the compressor 12. Between points D and A, the fluid passes through the condenser 14. Through the condenser 14, the fluid goes from the gaseous state to a diphasic state, then from the diphasic state to the liquid state (two phase changes). Thus, the condenser 14 includes a segment 14a, along which the fluid is in the gaseous state, a segment 14b along which the fluid is in the diphasic state, and a segment 14c, along which the fluid is in the liquid state.
In the case where the fluid is in the diphasic state, a coefficient α is applied to calculate the densities. This coefficient α is better known as volume fraction, or void fraction. This is the ratio between the volume occupied by the gas and the volume occupied by the liquid. In a manner well known in the literature, it is calculated from thermodynamic properties according to semi-empirical correlations.
Typically, the volumes of the segments 14b and 16a are weighted with this coefficient α.
During a later step e), the values calculated in steps c) and d) are next used to calculate the total mass M of refrigerant contained within the air conditioning system, using the following formula:
M=
One next compares, during a step f), the total mass M of refrigerant calculated in step e) with the total mass of refrigerant originally contained within the air conditioning system.
More specifically, step f) advantageously consists of determining a health index HIcharge of the air conditioning system 8, by obtaining the quotient of the total mass M of refrigerant calculated in step e) over the total mass of refrigerant originally contained in the air conditioning system. Typically, the total mass M of refrigerant is calculated in step e) by the calculator 40, which also copulate the health index HIcharge of the air conditioning system 8. To that end, the mass of refrigerant originally contained in the air conditioning system 8, i.e., in new condition, is stored as an input parameter in the information recording medium 44 of the calculator, i.e., in the memory.
Typically, the health index HIcharge is compared with a reference value, for example of about 80%, the air conditioning system then being considered no longer to work in a satisfactory manner if the health index is below the reference value, and otherwise being considered to work in a satisfactory manner.
Preferably, the process includes a step g) consisting of automatically emitting an alert signal if, at the end of step f), the air conditioning system is determined as no longer working in a satisfactory manner. This alert signal may for example take the form of an illuminated indicator lighting up on the driver's dashboard.
Advantageously, steps a) to f) are reiterated over time during the operation of the air conditioning system 8, preferably regularly with a predefined frequency. Typically, steps b) to f) are carried out automatically by the electronic calculator 40.
Alternatively, the air conditioning system 8 according to the invention is also applicable to railway vehicles not intended to carry passengers, for example locomotives, maneuvering vehicles such as light rail motor tractors, or railway maintenance vehicles. The air conditioning system 8 is then advantageously used to supply air conditioning to a space 10 received inside this vehicle, for example associated with a driver cabin or a merchandise transportation space.
The features of the embodiment and various considered alternatives that are not shown may be combined with one another to create new embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1758158 | Sep 2017 | FR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2089372 | Henney | Aug 1937 | A |
| 7631508 | Braun et al. | Dec 2009 | B2 |
| 9239180 | Ochiai | Jan 2016 | B2 |
| 9261542 | West | Feb 2016 | B1 |
| 20070163276 | Braun et al. | Jul 2007 | A1 |
| 20110036104 | Toyoshima et al. | Feb 2011 | A1 |
| Number | Date | Country |
|---|---|---|
| 2034261 | Mar 2009 | EP |
| 2472203 | Jul 2012 | EP |
| 2546588 | Jan 2013 | EP |
| Entry |
|---|
| Search Report for FR Application 1758158 dated Jan. 10, 2018. |
| Number | Date | Country | |
|---|---|---|---|
| 20190071103 A1 | Mar 2019 | US |
