Device for keeping a ventilation opening unobstructed

Abstract

According to the invention, the ventilation opening is provided with a heat exchanger, and a melting grating that is heat-conductingly connected to the heat exchanger is mounted in a space in front of the heat exchanger, said space being surrounded by a structure. The melting grating can be integrated into the heat exchanger or be retrofitted.

Description

[0001] Description

[0002] Device for keeping a ventilation opening clear

[0003] The invention relates to a device for keeping a ventilation opening free of snow and its use in a rail vehicle.

[0004] Many technical systems and devices have ventilation openings, for example, as air inlets for ventilation and cooling. Depending on their application, the systems and devices, and thus also the ventilation openings, can be exposed to different climatic conditions. In particular, they can be exposed to snow and ice, which poses the risk that the ventilation opening will be reduced in size or blocked. Despite low temperatures, such cases can lead to overheating and temperature-related shutdowns of the system or device because cooling air no longer reaches the cooling units in sufficient quantities.

[0005] This problem occurs, for example, in rail vehicles. Due to structural conditions, air inlets can be located in areas of the vehicle where snow drifts block these air inlets. To avoid this, especially in underfloor cooling systems, attempts are made to place the heat exchangers (often referred to as radiators) that need to be cooled on the outside of the rail vehicle so that the waste heat from these heat exchangers can be used to melt snow deposits. This works particularly well when the heat exchangers form the outer contour of the vehicle and therefore the surface to which ice and snow tend to adhere. The heat exchangers are attached to the ventilation opening and are designed, for example, as a grille, with the grille bars acting as channels through which a cooling medium (usually water) flows.The air is then drawn from the side of the vehicle through the heat exchanger and blown out downwards, with the air flow usually being supported by fans.

[0006] If a block of ice or snow adheres to the ventilation opening of a rail vehicle, it will be heated over a large area on the heat exchanger during operation. A melting surface is created between the heat exchanger and the snow block. Since this melting surface is large—namely, it is the size of the heat exchanger or the ventilation opening—and there are no other attachment points for the snow block, the snow block will fall off during operation of the heat exchanger.

[0007] In the case of many technical systems and devices, however, space requirements may make it necessary to arrange air inlets in enclosed areas which are nevertheless exposed to the outside climate. Enclosed means that the space in front of the ventilation opening is not completely free, but that there is a structure opposite and / or to the side at a greater or lesser distance which forms a boundary structure for the enclosed space. These boundary structures do not have to be continuous, i.e. the enclosed space does not have to be closed. Even if the heat-radiating heat exchanger is placed in front of the ventilation opening again in such a case, it is possible that a block of snow will settle in a different place, i.e. on a different boundary structure in the enclosed space which is not heated by the heat exchanger. The block of snow will not fall off this cold spot when the heat exchanger heats up.The heat exchanger may melt a small layer or area of ​​the snow block, but an insufficient channel is created to allow proper cooling air flow through the ventilation opening. This may lead to overheating or shutdown. Figures 1 and 2 illustrate this situation using the example of a rail vehicle, showing a bottom view of an underfloor area. In Figure 1, the enclosed area U is indicated by a line that is essentially determined by the boundary structures of the enclosed space. A ventilation opening 1 is provided with a heat exchanger 2a that is of grid-shaped design. The ventilation opening 1 is therefore not on the outside 3 of the vehicle.

[0008] Even if, in this case, the heat-radiating heat exchanger 2a is placed at the ventilation opening 1, a block of snow S can become trapped in several cold spots on the boundary structures of the enclosed space U in front of the heat exchanger 2a, as shown in Fig. 2. The snow block S is heated at most superficially by the heat exchanger, or the melting surface is too small for the snow block S to fall off due to this melted surface. The ice and snow block S therefore closes the heat exchanger 2a, and overheating can occur.

[0009] In order to solve the problem of such ice and snow accumulation in enclosed spaces, attempts have already been made to introduce aerodynamic protective measures such as cyclone separators, baffles, guide vanes, etc. Some of these have been optimized using CFD calculations (Computational Fluid Dynamics) and verified through tests in climate chambers. However, since ice and snow can occur in many different forms, both the CFD calculation and the verification in the climate chamber only illuminate very specific conditions of ice and snow. Under different weather conditions, different air humidity, etc., other, uninvestigated conditions arise which can again lead to problems. Under certain weather conditions, such ice and snow deposits have to be removed by hand using a shovel, pickaxe, etc., which leads to delays in rail traffic.

[0010] The object of the invention is to provide an improved device for keeping a ventilation opening free of snow, as well as a corresponding method. These devices are intended to be particularly suitable for use in a rail vehicle.

[0011] This object is achieved by a device having the features of patent claim 1, by a device having the features of patent claim 4 and by a method according to patent claim 9.

[0012] Advantageous embodiments of the invention are specified in the subclaims.

[0013] The invention is based on the idea of ​​equipping the ventilation opening with a heat exchanger and installing a grille in an enclosed space in front of the heat exchanger, which grille is thermally connected to the heat exchanger. Due to the thermal contact, the grille is heated during operation of the heat exchanger, melting snow and ice in the enclosed space in front of the ventilation opening. The grille is therefore referred to as a melting grille. The term melting grille covers any geometric construction that ensures air flow to the heat exchanger or the ventilation opening.

[0014] In a first variant, the heat exchanger and melt grid are integrated. The heat exchanger has an inlet and an outlet for a cooling medium, the heat exchanger having cooling channels for receiving the cooling medium, which are connected to the inlet and the outlet. The cooling medium therefore flows from the inlet into the cooling channels of the heat exchanger and on to the outlet. The melt grid is arranged in front of the heat exchanger and comprises channels for the cooling medium, which are connected to the inlet and the outlet. The cooling medium can therefore flow through the channels of the melt grid; in other words, the melt grid and the inlet and outlet are fluidically connected. When the device is installed in the ventilation opening and is in operation, the cooling medium is heated and also heats the melt grid.

[0015] The heat exchanger can be designed with any geometry; for example, the cooling channels can be grid-shaped or mesh-shaped. Two collecting tanks, in particular water collecting tanks, are preferably provided as inlet and outlet. The channels of the melt grid, which are formed, for example, by grid bars designed as hollow rods, are also connected to the two collecting tanks, so that the heat exchanger and the channels of the melt grid are hydrodynamically connected in parallel.

[0016] It is advantageous if the header boxes are extended forwards so that, when installed, they protrude into the enclosed space. In other words, the header boxes preferably extend in the direction of the surface normal of the heat exchanger (or the associated ventilation opening) such that, when the device is installed in the ventilation opening, the header boxes protrude into the enclosed space, i.e., they are not flush with the edge of the ventilation opening. Preferably, the channels of the melting grid open into the projecting part (i.e., the part protruding into the enclosed space) of the header boxes. This achieves an improved melting effect. In one embodiment, the channels of the melting grid run or are arranged three-dimensionally. The channels can also each have a three-dimensional (i.e., non-linear) geometry.Particularly preferably, they are designed linearly and arranged in at least two planes, which can be essentially parallel to the surface of the heat exchanger. When installed, a larger volume in front of the ventilation opening is heated more evenly, thus improving the melting process.

[0017] The cooling medium is preferably circulated using a coolant pump. The device with heat exchanger and melting grid is preferably aerodynamically and hydrodynamically dimensioned so that the total pressure loss—both for the flowing air and the flowing cooling medium—is at the operating point of the cooling water pump, as well as at the operating point of any fan that supports cooling. The melting grid is thus taken into account in the design of the entire cooling arrangement (in particular the heat exchanger, pump, and fan), also known as the cooling unit.

[0018] The melting grid is dimensioned so that the melted volume releases a sufficiently large flow cross-section to enable proper operation at these temperatures, even if the cooling unit is only operated periodically. Should ice and snow form again when the unit is shut down, they will be melted away when the cooling unit is reactivated.

[0019] With the melting grid according to the first variant, the melting of snow and ice is achieved with particularly high reliability, since the melting grid is flowed through by the cooling medium and is thus heated up well. In a second variant, the melting grid is designed as a mountable grid. The device comprises at least one fastening part, with the aid of which the melting grid can be mounted in front of the ventilation opening provided with a heat exchanger. In this case, thermal contact is formed between the melting grid and the heat exchanger. The fastening part is designed to mount the melting grid on an edge of the ventilation opening and / or on an inlet and / or outlet of the heat exchanger, in such a way that the melting grid projects into an enclosed space in front of the ventilation opening. After installation, the melting grid is therefore arranged in front of the ventilation opening.

[0020] In one embodiment, the melting grid is provided with connecting rods, which are preferably arranged between two fastening parts. The connecting rods can also each have a three-dimensional (i.e. non-linear) geometry. In particular with a linear geometry, the connecting rods can be arranged in one or more planes. It is particularly advantageous if the connecting rods are arranged in at least two planes, which, after installation, can lie essentially parallel to the surface of the heat exchanger. When installed, a larger volume in front of the ventilation opening is then heated more evenly, and the melting process is thereby improved.

[0021] The melt grid is particularly advantageous for use in a heat exchanger whose inlet and outlet are designed as header boxes, between which the cooling channels of the heat exchanger run. Such header boxes enable surface contact between the fastening part and the header box when the melt grid is installed, and thus good thermal contact between the melt grid and the heat exchanger by means of the fastening part. Since the coolant does not flow through the melt grid in this second variant, heating occurs exclusively through thermal conduction. The heat is conducted from the fastening part into the melt grid, so that the intake area of ​​the heat exchanger is also heated. The melt grid is suitable for a variety of heat exchangers; sufficient thermal contact must be established.The melting grid is aerodynamically designed so that the cooling airflow meets the cooling capacity requirement. It is also dimensioned so that a block of snow surrounding the melting grid is melted away over a sufficiently large cross-sectional area when the cooling unit is activated. The resulting air channel must be large enough to meet the cooling capacity requirement of the cooling unit at these temperatures.

[0022] The melt grid according to the second variant can be retrofitted and does not require any changes to the heat exchanger system, i.e. the heat exchanger and / or its inlet and outlet. In many applications, for example in rail vehicles, the heat exchangers used for cooling units are optimized and highly adapted to the prevailing boundary conditions to ensure their reliable function in all operating situations. A structural modification of the heat exchanger system is therefore only possible to a limited extent and is complex. Retrofitting with the melt grid of the second variant is possible without changing the heat exchanger; if necessary, a minor adjustment of the dimensioning of a fan or a coolant pump may be useful. The invention is explained in more detail below using exemplary embodiments. They show a schematic representation

[0023] Fig. 1 and 2 show a plan view of an underfloor area of ​​a rail vehicle according to the prior art to explain the problem underlying the invention

[0024] Fig. 3 is a simplified representation of a device according to the first variant

[0025] Fig. 4 is a plan view of an underfloor area of ​​a rail vehicle with a built-in device according to the first variant

[0026] Fig. 5 is a plan view of an underfloor area of ​​a rail vehicle with a built-in device according to the second variant.

[0027] Fig. 3 shows an exemplary embodiment of the first variant with a grid-shaped heat exchanger 2a, which has parallel cooling channels between an inlet and an outlet. The cooling medium used is, for example, water with an antifreeze agent, and the inlet and outlet are designed as collecting tanks 2b.

[0028] A melting grid 4 is arranged in front of the heat exchanger. It is grid-shaped and comprises parallel channels that also extend between the water collection boxes 2b and are connected to them. During operation, the cooling water also flows through the channels and is arranged in one plane.

[0029] The depth of the collecting boxes 2b (i.e., perpendicular to the plane of the heat exchanger, in this case the heat exchanger channels) is designed such that the channels of the melting grid 4 can open into the collecting boxes 2b at a distance from the channels of the heat exchanger 2a. When the device is installed in a ventilation opening of a rail vehicle, the collecting boxes 2b protrude forward from the surface of the ventilation opening, i.e., into an enclosed space. As a result, the melting grid 4 protrudes into the space, where ice and snow can accumulate.

[0030] The melting grid 4 is aerodynamically designed in such a way that the functioning of the heat exchanger is not or only slightly influenced, which in this case means that the grid bars or the associated channels are thinner and have a greater distance between them than the grid bars or cooling channels of the heat exchanger.

[0031] Fig. 4 shows another embodiment of the first variant after installation in a rail vehicle, with an underfloor view corresponding to Figure 2 being shown. The collecting boxes 2b are installed in the ventilation opening 1 in such a way that they protrude into the enclosed space. The channels of the melt grid 4 connect the two collecting boxes 2b and are arranged in three levels 4a, 4b, 4c in front of the heat exchanger 2a in the enclosed space. A cooling water pump (not shown) builds up a pressure difference between the two water collecting boxes 2b, whereby the cooling water can flow both through the channels of the melt grid 4 and through the heat exchanger. The channels of the melt grid 4 and the channels of the heat exchanger 2a are now hydrodynamically connected in parallel via the water collecting boxes 2b.The cooling water is still cooled primarily in the heat exchanger—the function of the heat exchanger is thus practically unchanged—but heat exchange also occurs via the channels of the melting grid 4 as the cooling air flows past them. A fan 7 of the cooling unit supports the cooling.

[0032] If a block of ice and snow builds up in front of heat exchanger 2a in winter, the channels of melting grid 4 are embedded in this block of ice and snow. As soon as the cooling unit is activated, the channels of melting grid 4 are heated by the cooling water and melt the block of ice and snow to the size of melting grid 4.

[0033] Fig. 5 shows an embodiment of the second variant after installation in a rail vehicle, with an underfloor view corresponding to Fig. 4 being shown.

[0034] The melting grid 4 is attached flat to the header boxes of the heat exchanger 2a so that there is good heat transfer between the header box 2b and the melting grid 4. For this purpose, the melting grid has heat-conducting angles 6 to which the grid bars 4 of the melting grid are attached so that thermal contact is formed. Since the header boxes do not protrude from the ventilation opening and are located behind the angles, they cannot be seen in Figure 5. The angle 6 can be connected to the header box 2b using weld bolts on the header box and screws 6a or using other suitable fastening structures between the housing of the cooling unit and the melting grid 4, as long as it is ensured that the melting grid is sufficiently heated by this fastening structure or the fastening parts when the cooling unit is in operation. In the latter case in particular, no modifications to the heat exchanger are necessary.In this design, the melting grid bars are arranged in four levels (4a-4d). The advantage of both variants is that accumulating snow is continuously melted away using waste heat, as the critical areas are heated. As soon as a cooling unit is operating, this waste heat is available and used for the melting process. This technology works with all types of snow and under all aerodynamic conditions.

Claims

Patent claims 1. Device for keeping a ventilation opening free of snow - with a heat exchanger (2a) for installation in the ventilation opening (1), - with an inlet (2b) and an outlet (2b) of the heat exchanger for a cooling medium, wherein the heat exchanger has cooling channels for the cooling medium which are connected to the inlet (2b) and the outlet (2b) of the heat exchanger (2a), - with a melting grid (4) which is arranged in front of the heat exchanger (2a) and comprises channels for the cooling medium which are connected to the inlet (2b) and the outlet (2b).

2. Device according to the preceding claim, characterized in that the inlet (2b) and the outlet (2b) of the heat exchanger (2a) are each designed as a collecting tank for the cooling medium.

3. Device according to one of the preceding claims, characterized in that the channels of the melting grid (4) are arranged in one or more planes (4a - 4c), wherein the plane or planes are arranged substantially parallel to a surface of the heat exchanger (2a).

4. Device for keeping a ventilation opening free of snow, wherein the ventilation opening (1) is provided with a heat exchanger (2a) with an inlet (2b) and an outlet (2b) for a cooling medium, - with at least one fastening part (6, 6a) for mounting the device on the heat exchanger (2a) and / or on the inlet (2b) and / or on the outlet (2b) and / or at an edge of the ventilation opening (1) in front of the ventilation opening, forming a thermal contact, - with a melting grid (4) which is fastened to the fastening part (6, 6a) of the device to form a thermal contact in such a way that it is arranged in front of the heat exchanger (2a) after the device has been mounted on the ventilation opening.

5. Device according to the preceding claim, characterized in that the melting grid comprises heat-conducting rods arranged in one or more planes, the plane or planes being arranged substantially parallel to a surface of the heat exchanger after mounting the device on the ventilation opening by means of the fastening means.

6. Use of a device according to one of the preceding claims in a rail vehicle, in particular for a ventilation opening (1) in an enclosed space.

7. Use of a device according to one of claims 1 - 3 in a rail vehicle, characterized in that the melting grid (4) and the collecting box protrude into an enclosed space after assembly at the ventilation opening.

8. Rail vehicle with a device according to one of claims 1 - 5.

9. Method for keeping a ventilation opening clear of Snow, in which the ventilation opening is provided with a heat exchanger (2a) and a melting grid (4), wherein the melting grid is connected to the heat exchanger in a heat-conducting manner, in which heat is transferred from the heat exchanger (2a), in particular from its collecting box, to the melting grid (4).

10. Method according to the preceding claim, characterized in that a coolant is passed through channels of the melting grid (4).

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