EA044586B1 - AIR CONDITIONING DEVICE FOR VEHICLE - Google Patents

Description

Cross reference to related applications

This application represents a translation into the national phase of the International Patent Office

Application No. PCT/DE2020/100718 (filed August 18, 2020), the priority of which is claimed by the filing date (August 27, 2019) of German patent application No. 20 2019 104 698.8. The entire disclosure of these applications is incorporated herein by reference.

Prerequisites

Field of technology

The invention disclosed herein relates to an air conditioning apparatus for a rail vehicle, wherein said apparatus is suitable for flammable refrigerants and is configured as a compact piece of equipment for installation on the roof of the vehicle and at least includes sections for air handling and a compressor-liquefier unit and, optionally, air exhaust sections, electrical distribution box and/or muffler.

State of the art

Various refrigerants are known for air conditioning devices in vehicles, in which the use of synthetic refrigerants in particular is problematic from an environmental point of view. For this reason, R134a refrigerant is very widely used in motor vehicles as well as rail vehicles. However, this refrigerant, when released into the environment, acts as a greenhouse gas. Therefore, the use of R134a refrigerant for new passenger cars in the European Union was phased out on January 1, 2017.

As an alternative to R134a, the refrigerant currently predominantly used is R1234yf, which has a much lower greenhouse effect but is flammable and is classified as an A2L refrigerant. However, even the use of this refrigerant is currently criticized by experts. For example, when released at temperatures >250°C, highly toxic hydrofluoric acid (HF) is formed, and as a decomposition product that accumulates, in particular in water, persistent trifluoroacetic acid (TFA trifluoroacetic acid) is formed in the environment. Due to the associated risks, the use of hydrofluoroolefin (HFO) refrigerants such as R1234yf is also generally avoided.

An alternative is to use carbon dioxide (R744) as a natural refrigerant. However, the use of R744 results in relatively complex equipment processing solutions due to the high device pressure required compared to other refrigerants. Moreover, at high ambient temperatures there is a significant deterioration in the coefficient of performance (COP) and thus a significant increase in the energy requirement for air conditioning. In addition, as the ambient temperature rises, the cooling capacity is sharply reduced, which can be compensated for by a corresponding increase in the size of the components.

It is therefore clear that the refrigerants used today ultimately represent a compromise between different requirements in terms of functionality, ecology and safety. There is a need for the use of refrigerants for vehicle air conditioning devices, in particular for rail vehicles, which are environmentally non-critical when released into the environment, demonstrate high energy efficiency over the entire operating range and can benefit from the knowledge and experience of cold steam technology used until now. As for rail vehicles, these units are mainly designed as compact units for the roof of the vehicle. Regardless of the specific design, such compact air conditioning units typically contain an air handling section and a compressor-liquefaction section and may contain air exhaust equipment, an electrical distribution box, and/or muffler sections.

As a solution to the above requirements, flammable hydrocarbons such as propane (R290), propylene (R1270) or isobutane (R600a) are of interest as refrigerant alternatives. These refrigerants are widely used in direct expansion applications with limited charge quantities (<150 g or <500 g), particularly in stationary applications. If larger charge quantities are required to provide higher refrigeration capacity, the use of indirect expansion devices is preferred due to the ignition potential of these direct expansion devices.

For air conditioning in rail vehicles, virtually no flammable refrigerants are currently used, either in direct expansion or indirect expansion, due to the explosion and fire hazards associated with such refrigerants. The above risk is reduced in an indirect evaporation device if the air conditioning device is equipped with secondary circuit means. In this case, the required cooling (or heating) power is provided in the primary circuit using flammable refrigerants in conventional refrigerant compression circuits, with the primary circuit located outside the transport

- 1 044586 means and thus does not have a direct connection to the vehicle interior. This cooling power is transferred via heat exchangers (preferably plate heat exchangers) to a secondary circuit, which is designed, for example, as a brine circuit with water-glycol mixtures.

A technical solution of this type is known from the international publication WO 2018/137908 A1. According to this document, a rail vehicle has a primary refrigerant circuit that is located outside the vehicle and is structurally completely separate from the passenger compartment. The secondary coolant circuit is located at least partially inside the rail vehicle. Heat exchange between the primary refrigerant circuit and the secondary refrigerant circuit is ensured by an intermediate heat exchanger located under the floor in the outer area. As a result, the primary coolant circuit is completely removed from the passenger compartment of the rail vehicle. This design means that when flammable substances are used, the safety considerations that need to be taken into account mainly concern the outer zone, while the inner zone can be considered as safe as known devices. This means that it is also possible to use refrigerants that, for safety reasons, have so far been practically not used for air conditioning in passenger compartments. Thus, WO 2018/137908 A1 proposes the use of flammable refrigerants such as propane, which is well suited as a refrigerant from a functional point of view, but has so far been largely unused due to problems associated with fire and explosion hazards. which were mentioned above.

Taking into account the state of the art described in WO 2018/137 908 A1 and similar proposed solutions, it can be expected that the acceptance of flammable refrigerants in air conditioning devices for rail vehicles will increase significantly in the medium term. However, it should be noted that using an indirect loop will still result in disadvantages in energy use due to heat losses in the intermediate heat exchanger, as well as additional weight and the need for additional installation space. Thus, for the widespread use of flammable refrigerants, there is a need for a direct evaporation device that eliminates these disadvantages. To ensure a high level of fire and explosion safety, including in the event of possible operational malfunctions, in air conditioning devices of rail vehicles, additional design solutions are ultimately required, which lead to the need for special designs of various components.

A similar solution is known from patent document DE 19522099 A1, which describes an arrangement of fans and other components in pressure-tight chambers. In addition, patent document DE 9319874 U1 proposes a complete hermetic seal of several units in the refrigerant circuit of an air conditioning device in a pressure-tight structure to prevent uncontrolled refrigerant leaks. This approach is inherently of interest to those skilled in the art. However, none of the published documents contain any suggestions on how exactly the proposed idea might be implemented. In addition, the solutions described are not suitable for flammable refrigerants.

The essence of the invention

It is an object of the present invention to provide a direct expansion device in which conditioned air for a passenger area is contained within the air conditioning device so that in the event of a leak in the refrigerant transfer units, flammable refrigerant is prevented from entering the vehicle interior.

This problem is solved due to the fact that the units and components for transferring the refrigerant are located outside the zones of the comfortable ventilation channels, in a separate housing and open to the environment. Thus, the components of the ventilation unit, e.g. mixed air dampers for outdoor/ambient air, air filters, dampers, supply air fan, evaporator and heating control, as well as their boundaries for outdoor air intake and/or ambient air intake and for injecting fresh air are located within an airtight and/or pressuretight duct in the compact unit housing or, alternatively, in an air conditioning device so configured. All components outside said channel are designed to open to the environment, so that any possible leakage that may occur is diverted or vented to the outside.

Thus, the comfort ventilation channel, i.e. the air to be supplied to the passengers in the vehicle is separated in said device and sealed from a refrigerant circuit, in which the refrigerant technical parts are configured as a typical and known sealed refrigerant circuit. Therefore, in one aspect, the novelty of the present invention compared to the prior art is that all refrigerant transfer parts are located outside the comfort ventilation duct and are located in the housing so that they are protected from damage or accidental entry. In this case, the refrigerant transfer parts are arranged so that they are open to the environment to ensure that any leaks are vented to the outside through passive ventilation and to prevent flammable concentrations over an extended period of time. If there are no potential ignition sources, the refrigerant transfer parts may also be located in a separate, enclosed, airtight area. In addition, to prevent refrigerant from entering the comfort ventilation duct area, a suitable seal (technical seal) is installed between the two areas of the comfort ventilation duct and the housing with the refrigerant transfer components. Additional advantageous embodiments are indicated in the dependent claims, and their technical features are described in an exemplary embodiment.

According to the technical solution according to the present invention, the auxiliary components of an air conditioning device for a rail vehicle, which require air treatment, are insulated so that contact of these auxiliary components with flammable refrigerants resulting from leakage is prevented due to the airtight and/or pressuretight channel designs. In this case, the acceptability of using flammable refrigerants in air conditioning devices for rail vehicles is increased because it is now possible to provide fire and explosion protection to the interior zone even in the event of an uncontrolled release of flammable refrigerant to the exterior zone.

Brief description of drawings

An exemplary embodiment of the present invention will now be described in more detail with reference to the drawings.

Fig. 1 shows in a simplified manner the basic structure of an air conditioning device for a rail vehicle, which is suitable for the use of flammable refrigerants and is designed as a compact unit of equipment capable of being installed on the roof of a vehicle, wherein the housing of the air conditioning device is not shown,

Fig. 2 shows in a simplified manner the first variant of the arrangement of the components of the air conditioning device in an airtight duct,

Fig. 3 shows in a simplified manner a second variant of the arrangement of air conditioning device components in a pressure-tight duct,

Fig. 4 shows in a simplified way the third option for arranging components of an air conditioning device in an airtight duct,

Fig. 5 simplifies the fourth embodiment of the arrangement of the air conditioning device components in a pressure-tight duct, and

Fig. 6 is a simplified example of a specific embodiment of evaporator refrigerant transfer line sections for airtight or pressuretight duct designs.

Detailed description

In fig. 1 shows the basic structure of an air conditioning device for a rail vehicle (not shown), which is suitable for the use of flammable refrigerants of categories A2, A2L and A3 and is designed as a compact unit of equipment for installation on the roof of a rail vehicle. Only the main air handling components are shown, and the air conditioning unit housing is not illustrated. Accordingly, the air conditioning device contains an additional exhaust air section A, an air treatment section B, an additional electrical distribution box C and a compressor-liquefier unit D. Sections B and A may contain, as main components, pressure surge valves 1, mixed air dampers 2 , intended for outdoor/ambient air, air filter 3, supply air fan 4, evaporator 5, heating control means 6, supply air dampers 7 and exhaust fan 8, as shown in the drawing. In addition, the boundaries for fresh air inlet a, ambient air inlet b, exhaust air inlet c, exhaust air inlet d, fresh air outlet el and fresh air outlet e2 are shown.

In fig. 2 shows an arrangement of several nodes shown in FIG. 1, inside an airtight duct in the housing of the air conditioning device. This airtight channel is simplistically shown with a slightly thicker dotted outline. Accordingly, dampers 2 for mixed air intended for outside/ambient air, air filter 3, dampers 7 for supply air, supply air fan 4, evaporator 5 and heating control means 6 of section B for air treatment, as well as their boundaries relative to The fresh air inlet a and/or the ambient air inlet b and relative to the fresh air outlets e1 and/or e2 are located inside an airtight channel in the housing of the air conditioning device, which is designed as a compact unit of equipment. In this case, the designation AB means the external environment visible from said duct, and the designation IB means the internal air handling area visible from the said duct, wherein the area AB is open to the environment and possible potential leakage can be diverted or vented to the outside. , and zone IB is a protected internal zone in which leakage is not expected since the evaporator is designed as a protected evaporator.

In fig. 3 shows a modified design of the device shown in FIG. 2. In this embodiment, section A for the outgoing air together with the pressure surge valve 1 and its boundaries with the inlet d of the outgoing air and with the opening c for the outgoing air are also located inside a pressure-tight channel in the housing of the air conditioning unit. In this drawing, the pressure-tight channel is also conventionally shown with a slightly thicker dotted contour line. Likewise, the designation AB denotes the external environment visible from said duct, and the designation IB denotes the internal air handling area visible from said duct.

In fig. 4 shows a modified version of the arrangement shown in FIG. 2. In this embodiment, the electrical junction box C is also located inside an airtight duct in the housing of the air conditioning device. In this drawing, the airtight channel is also conventionally shown with a slightly thicker dotted contour line. Similarly, the designation AB represents the external environment visible from said duct, and the designation IB represents the internal air handling area visible from said duct, wherein the AB area is open to the environment and possible leakage can be diverted or vented to the outside, and the IB area represents This is a protected internal zone in which no leaks are expected, since the evaporator is designed as a protected evaporator.

In fig. 5 shows an embodiment that is further modified compared to the embodiment in FIG. 4, and in this case (similar to the variant in Fig. 3) section A of the device for outgoing air together with the pressure surge valve 1 and its boundaries with the inlet d of outgoing air and with the opening c for outgoing air are also located inside an airtight and pressure-tight channel in the housing of the air conditioning unit. In this case, the airtight and pressuretight channel is also conventionally shown with a slightly thicker dotted contour line. Similarly, the designation AB represents the external environment visible from said duct, and the designation IB represents the internal air handling area visible from said duct, wherein the AB area is open to the environment and possible leakage can be diverted or vented to the outside, and the IB area represents is a protected internal area in which no leaks are expected, since the evaporator is designed as a protected evaporator.

In fig. 6 shows an example of the specific arrangement and design of the refrigerant transfer line sections of the evaporator 5. FIG. Figure 6 shows two sections of the refrigerant circuit, section BP (tube bundle inside the evaporator) and section BR (zone of the refrigerant circuit pipes in the air handling section), as well as the electrical distribution box C and the compressor-liquefier unit D. The boundaries f1 and f2 are made for closed refrigerant lines in sections BR and C, and dividing walls g1 and g2 are designed to provide a seal to the evaporator. In addition, evaporator 5, compressor 9, liquefier 10, inlet pressure sensor 11, solenoid valve liquid line 12, solenoid valve inlet line 13, auxiliary solenoid valve bypass line 14, inlet line 15, liquid line 16, and auxiliary bypass line 17 are shown as the main components for each refrigerant circuit.

The straight evaporator tubes 5, which are delimited by walls g1 and g2 and located in zone IB, are the only components of the refrigerant circuit that are located in the airtight and pressuretight duct zone and can be closed in the event of damage or a significant sudden drop in pressure (major leak). refrigerant outside or inside). In this case, the risk is further minimized. Shutdown occurs by closing solenoid valve fluid line 12, as well as solenoid valves 13 and 14 on inlet line 15 and bypass line 17. Additionally, this shutoff zone can be emptied using the pump out function before shutting off the refrigerant circuit. This pumping is accomplished by closing the solenoid valve fluid line 12 and the solenoid valve bypass line 14 while the compressor 9 is running. In this case, the entire piping connection from the solenoid valve fluid line 12 to the inlet side of the compressor 9 is emptied. More specifically, this refers to the line 16 for fluid downstream of solenoid valve fluid line 12, through zones f1 and f2, and then through the evaporator tube stack (EP) back through inlet line 15 and bypass line 17 through zones f1 and f2. When a certain suction pressure is reached, the compressor 9 is turned off and the solenoid valve 13 of the inlet line 15 is closed. The location of the solenoid valves 12, 13 and 14 is given as an example only and can, for example, be provided next to the evaporator 5. Due to this, even after the refrigerant circuit has been switched off and emptied, additional monitoring of the emptied section can be ensured using the inlet pressure sensor 11, located in the section to be emptied, and pumping is repeated when the specified pressure is reached in the section to be emptied. In this case, the increase in pressure is due to the presence of refrigerant in the section being emptied. This provides the possibility of additional monitoring of the emptying progress of the section being switched off.

Claims (4)

CLAIM 1. An air conditioning device for a rail vehicle, wherein said device is suitable for the use of flammable refrigerants of categories A2, A2L and A3 and is designed for installation on the roof of the vehicle, wherein said device at least contains sections of equipment for section B of air treatment, compressor- liquefaction equipment D and an outlet air section A, wherein the outlet air section A at least has first boundaries with an outlet air inlet and an outlet air opening, and the air treatment section B at least has second boundaries with an outside air inlet and with ambient air inlet, as well as fresh air outlet, air filter, evaporator and fresh air fan, with a mixed air damper for fresh or ambient air, fresh air dampers and a heating control, with assemblies and components for transferring the refrigerant of the device air conditioning units are located outside the areas of the ventilation ducts through which air is supplied to passengers in the vehicle, in a separate housing and open to the environment, with at least a mixed air damper (2) intended for fresh or ambient air, an air filter ( 3), dampers (7) for supply air, supply air fan (4), evaporator (5) and means (6) for controlling the heating of the air treatment section (B), as well as second boundaries with the inlet (a) of outside air or with the inlet (b) ambient air, and the supply air outlets (e1 and/or e2) are located within an airtight or pressuretight duct in the housing of said air conditioning device. 2. The device according to claim 1, in which the valve (1) of pressure surges of the section (A) of the exhaust air and the first boundaries with the inlet (d) of the exhaust air and with the hole (c) for the exhaust air are also located inside a pressure-tight channel in the housing the specified air conditioning device. 3. The apparatus of claim 2, wherein the electrical junction box (C) is also located within an airtight or pressuretight duct in the housing of said air conditioning apparatus. 4. The apparatus of claim 1, wherein the sections of the evaporator refrigerant transfer line (5) are located as a single component of the refrigerant circuit in the area of an airtight or pressuretight duct, and are configured to be disconnected, emptied in an expandable manner, and emptied in an expandable and in a traceable manner.