motor vehicle with a fuel cell system

Abstract

The invention relates to a motor vehicle with a fuel cell system (5) to which an intake system (3) is assigned, through which fresh air can be drawn in and supplied to the fuel cell system (5) under pressure, wherein the intake system (3) has a compressor (9) that draws in and compresses the fresh air and directs the compressed charge air (L) to the fuel cell system (5) via a charge air line (11) and an charge air cooler. According to the invention, the charge air line (11) is guided at least partially through a longitudinal body member (13) of the vehicle body in the longitudinal direction (x). The longitudinal body member (13) forms the charge air cooler.

Description

[0001] The invention relates to a motor vehicle with a fuel cell system and an associated intake system according to the preamble of claim 1.

[0002] In practice, a fuel cell system installed in a motor vehicle consists of a fuel cell to which hydrogen or a hydrogen-containing gas can be supplied as fuel on the anode side and fresh air as oxygen on the cathode side. The fuel cell system includes an intake system that supplies the fuel cell with charge air. This intake system comprises an air filter and a compressor that compresses the incoming charge air. The compressed charge air exiting the compressor has a comparatively high process temperature. This poses a risk that the hot, pressurized charge air could cause thermal damage to the fuel cell.To avoid such thermal damage to the fuel cell, a vehicle of the generic type with a fuel cell system is known from DE 10 2012 018 874 A1, the intake system of which additionally has a charge air cooler with which the pressurized charge air supplied to the fuel cell system can be cooled.

[0003] The fuel cell system is typically installed in the front of the vehicle. If the fuel cell system is installed in the vehicle floor instead, the following disadvantages arise: The floor-mounted arrangement of the fuel cell system can result in a positioning of the intake system that is structurally unfavorable for the overall vehicle package. Furthermore, all fluid lines (i.e., fresh air, coolant, and exhaust) must be routed through the entire vehicle. Such routing leads to adverse pressure losses. Due to space constraints within the vehicle, the associated intake system (air filter and compressor) for fresh air must be located in the rear of the vehicle.Due to such complex circumstances, it is very disadvantageous from the point of view of the overall vehicle package to install the charge air cooler required for charge air cooling in the intake path leading to the fuel cell system.

[0004] DE 10 37 870 A1 discloses a vehicle with a radiator for cooling the vehicle's internal combustion engine. DE 10 2016 203 890 A1 discloses a body structure element for a vehicle with an integrated humidifier for a fuel cell system.

[0005] The object of the invention is to provide a motor vehicle with a fuel cell system, the associated intake system of which can be installed in the motor vehicle in a space-saving manner.

[0006] The problem is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the dependent claims.

[0007] According to the invention, the charge air cooler is no longer installed in the vehicle as a separate, independent functional unit (i.e., a heat exchanger). Rather, according to the invention, a structural element of the vehicle body is used in a dual function, additionally as such a charge air cooler. Against this background, according to the characterizing part of claim 1, the charge air duct is routed at least partially through a longitudinal body member of the vehicle body in the longitudinal direction. The longitudinal body member thus acts not only as a structural element but also, in a dual function, as a charge air cooler.

[0008] According to the invention, instead of an additional heat exchanger (i.e., charge air cooler) for conditioning the heated charge air, the longitudinal member of the vehicle body can function as a heat exchanger. Because the air duct is integrated within the longitudinal member, it acts as a heat exchanger with the aid of additional cooling surfaces. The air transfers heat to the material of the longitudinal member, which in turn transfers it to the surrounding airflow, similar to an air-cooled combustion engine. In addition to heat dissipation, the cooling fins can simultaneously increase the rigidity of the longitudinal member structure, thereby improving its crash performance in terms of failure resistance through controlled folding. The cooling fins can be integrated directly into the manufacturing process of the longitudinal member, e.g., extrusion, or can be incorporated as an additional component during assembly.

[0009] Another alternative to air cooling is targeted heat exchange within the longitudinal beam structure by means of a cooling airflow circulating within the beam, which is directed into the beam via targeted intake points (e.g., NACA ducts). The cooling principle is similar to that of an air-to-air heat exchanger.

[0010] According to one design variant, an air-water cooling system can be used, in which the compressed charge air is cooled by coolant. In this system, the charge air flow is cooled by a coolant flowing within the longitudinal member. For example, the main coolant circuit is routed into the longitudinal member, and the coolant cools the heated, compressed air from the compressor according to the principle of an air-to-water heat exchanger. The coolant is then fed back into the cooling circuit at the end of the longitudinal member and cooled accordingly via the main cooling circuit (air-to-water heat exchanger).

[0011] Another alternative involves air-water vapor cooling, i.e., cooling by enthalpy of vaporization. In this case, the charge air flow is cooled via enthalpy of vaporization. For this purpose, the water produced by the fuel cell is directed towards the longitudinal frame structure (exhaust gas flow) and sprayed onto the air duct within the frame. The evaporation of the cooling water on the surface of the air duct, due to the change of state from liquid to gaseous, extracts heat from the compressed air and thus cools it (a similar cooling principle is used in high-performance gasoline engines for internal mixture cooling).

[0012] The following aspects of the invention are highlighted in detail: In one technical implementation, the intake system can no longer be positioned in the front of the vehicle (as is usual in the prior art), but rather in the vehicle floor (in particular a sandwich floor structure). In this case, all media lines (fresh air, coolant, and exhaust gas) must be routed through the entire vehicle. With the above installation configuration, the fuel cell system can be arranged offset forward in the longitudinal direction of the vehicle relative to the intake system. The longitudinal offset between the rear intake system and the front fuel cell system is bridged by the charge air line routed within the longitudinal body member.

[0013] In a technical implementation, the body longitudinal member can be a hollow member with a closed cross-section. The charge air line can be routed through this hollow member. Preferably, an additional coolant line can also be routed through the body longitudinal member along with the charge air line. This coolant line is in thermal contact with the charge air line to ensure optimal heat transfer.

[0014] In a first embodiment, the charge air duct can be routed through the longitudinal body member with free clearance from the hollow frame wall, creating a gap between the charge air duct and the hollow frame wall. This gap can define the aforementioned coolant line. In this case, the cross-sectional area of ​​the coolant line is limited by the outer circumference of the charge air duct wall and the hollow frame wall.

[0015] In the above design variant, the cooling medium flows through the inside of the body longitudinal member. In contrast, in another design variant, the charge air duct running through the body longitudinal member can be in thermal contact with the hollow wall of the body longitudinal member. In this case, the body longitudinal member can be surrounded by the cooling medium on the outside.

[0016] The aforementioned thermal connection between the charge air duct and the hollow beam wall can preferably be achieved by thermal bridges, in particular by thermally conductive sheet metal webs, to ensure optimal heat transfer. The sheet metal webs can bridge the gap between the charge air duct and the hollow beam wall.

[0017] Alternatively and / or additionally, to increase cooling performance, the body's longitudinal members can be fitted with cooling fins on their outer surface, allowing ambient air to flow around them. These cooling fins also serve a dual function: stiffening the longitudinal member structure in the event of a crash (preventing the longitudinal member structure from folding up in a crash).

[0018] In another embodiment, the charge air line and the coolant line can be integrated into a double-pipe arrangement, which has a radially inner pipe wall and a radially outer pipe wall. The inner and outer walls are separated by a gap that forms the coolant line. The radially inner pipe wall, on the other hand, defines the charge air line. The outer wall can be separated from the hollow beam wall by a free gap to facilitate easy routing of the double-pipe arrangement within the vehicle body.

[0019] In another embodiment, a cooling system with a spray device can be integrated into the body's longitudinal member. Using this spray device, the cooling medium can be applied to the outer surface of the charge air duct, forming a film of cooling medium on this surface. The charge air duct is thus cooled by utilizing the enthalpy of vaporization generated when the cooling medium film evaporates, thereby increasing the cooling capacity compared to conventional flow-through cooling.

[0020] An embodiment of the invention is described below with reference to the accompanying figures.

[0021] They show: Fig. 1 in a roughly schematic top-down view of a vehicle with an integrated fuel cell system; Fig. 2 and Fig. 3 charge air and coolant lines, each guided in the longitudinal body member, according to a first embodiment; Fig. 4 and Fig. 5 a second embodiment of a body longitudinal member according to the invention; Fig. 6 and Fig. 7 a third embodiment of a body longitudinal member according to the invention; and Fig. 8 and Fig. 9 a fourth embodiment of a body longitudinal member according to the invention.

[0022] In the Fig. Figure 1 shows the outline of a vehicle in a top view, indicated by a dashed line. The vehicle's drive system is a fuel cell system. 5 up, which in the Fig. 1 is only shown to the extent necessary for understanding the invention. The fuel cell system 5 is an intake system 3 assigned to the rear of the vehicle 1is located in the vehicle. The intake system 3 is in the Fig. 1. It is constructed in two parts, namely from an air filter. 7 and a compressor downstream in the direction of flow 9 . By means of the intake system 3 Fresh air is drawn in from the vehicle's surroundings and compressed in the compressor. 9 compressed. The compressor 9 is on its pressure side via a charge air line 11 with the fuel cell system 5 fluidically connected. According to the Fig. 1 is the fuel cell system 5 via a longitudinal offset Δx in front of the intake system 3 Installed in the vehicle, for example in the vehicle floor. The longitudinal offset Δx will be in the Fig. 1 from the charge air pipe 11 bridged.

[0023] As from the Fig. As can be seen further in section 1, the charge air line runs 11space-saving installation within a body longitudinal member designed as a hollow beam 13 The body longitudinal member 13 limited on the inside in the cross-section yz considered ( Fig. 2) an outwardly closed hollow profile through which the charge air line 11 has been relocated.

[0024] In the Fig. 2 or Fig. 3 is the charge air line 11 with distance a to the hollow beam wall through the body longitudinal member 13 guided, specifically forming a flow gap 15 ( Fig. 2 or Fig. 3), which acts as a cooling medium line. In the Fig. 2 or Fig. 3 the flow gap 15 (that is, the coolant line) through the body longitudinal member 13 guided and permeated by ambient air. The body longitudinal member provides for this purpose. 13 in the Fig. 3 a streamlined air intake 17as well as an air outlet that is also arranged in an aerodynamically favorable manner 19 on, between which the ambient air during a vehicle journey in the direction of travel FR is introduced as a cooling medium K.

[0025] In the Fig. 2 or Fig. 3 is the one through the body longitudinal member 13 guided charge air line 11 except for thermal connection with the hollow beam wall of the body longitudinal member 13 and is the body longitudinal member 13 The cooling medium (ambient air) flows through it internally. This results in a [condition] within the longitudinal body member. 13 an air-to-air cooling system.

[0026] In contrast, in the Fig. 4 and Fig. 5 of the body longitudinal members 13 The cooling medium K (ambient air) no longer flows through the interior, but rather around the exterior. With regard to good cooling performance, the body longitudinal member features... 13 Cooling fins on the outside21 on, which are exposed to airflow during driving. To increase heat transfer between the hollow beam wall of the body longitudinal member. 13 and the one in the body longitudinal member 13 relocated charge air line 11 are in the Fig. 4 and Fig. 5 as thermal bridges sheet metal webs 23 provided for, which the free passage gap 15 in the body longitudinal member 13 bridge.

[0027] In the Fig. 6 and Fig. Figure 7 shows another embodiment in which the charge air line 11 and the cooling medium line in a double pipe arrangement 26 are integrated. The double-pipe arrangement 26 has a radial inner pipe wall 25 on, which the charge air line 11 limited, and a radially outer pipe wall 27 , which span an annular gap 29 from the radial inner pipe wall 25is spaced apart. The annular gap 29 forms the cooling medium line. An example is shown in the Fig. 6 and Fig. 7 the cooling medium K cooling water, which enters the annular gap via connections 29 the double-pipe arrangement 26 It is introduced and exited.

[0028] With regard to the ease of laying the double pipe arrangement 26 is between the radially outer pipe wall 27 and the hollow beam wall still has a gap through it 15 present, so that the double pipe arrangement 26 loosely through the hollow profile of the body longitudinal member 13 It can be relocated.

[0029] In the Fig. 8 and Fig. Figure 9 shows a further embodiment in which air-to-air cooling is used instead of air-to-air cooling. For this purpose, the longitudinal body member is... 13 a cooling system with a spray device 29assigned. The spray device points in the longitudinal direction of the vehicle. x Spacing spray nozzles 31 which are supplied with cooling medium (i.e., water) by the cooling system. By means of the spray nozzles. 31 is applied to an outer circumferential surface of the charge air pipe 11 A film of cooling medium is sprayed on. Cooling thus takes place by utilizing the enthalpy of vaporization resulting from the evaporation of the cooling medium film.

[0030] To increase the cooling effect, it is preferable if the free passage gap 15 between the charge air line 13 and the hollow beam wall of the body longitudinal member 13 Additionally, it is permeated with another cooling medium (i.e., ambient air), as shown in the preceding exemplary embodiments. Reference symbol list 1 Rear axle 3 Intake system 5 Fuel cell system 7 air filters 9 compressors 11 Charge air pipe 13 body longitudinal members 15 Passage gap 17 Cooling air intake 19 Cooling air outlet 21 cooling fins 23 sheet metal walkways 25 radial inner pipe wall 26 Twin-pipe arrangement 27 radial outer pipe wall 29 annular gap 30 Spray device 31 spray nozzles Δx longitudinal offset a distance QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 102012018874 A1

[0002] DE 1037870 A1

[0004] DE 102016203890 A1

[0004]

Claims

[1] Motor vehicle with a fuel cell system (5) to which an intake system (3) is associated, through which fresh air can be drawn in and supplied to the fuel cell system (5) under pressure, wherein the intake system (3) has a compressor (9) which draws in and compresses the fresh air and which directs the compressed charge air (L) to the fuel cell system (5) via a charge air line (11) and a charge air cooler, characterized by , that the charge air line (11) is guided at least partially through a body longitudinal member (13) of the vehicle body in the longitudinal direction (x), and that the body longitudinal member (13) forms the charge air cooler. [2] Motor vehicle according to claim 1, characterized by, that the intake system (3) is located in the rear of the motor vehicle (1), and / or that the fuel cell system (5) is located offset forward by a longitudinal offset (Δx) to the intake system (3), and that in particular the longitudinal offset (Δx) is bridged by the charge air line (11). [3] Motor vehicle according to claim 1 or 2, characterized by , that the body longitudinal member (13) is a hollow member which has a hollow profile with a cross-section (yz) closed through which the charge air line (11) is at least partially guided, and / or that a cooling medium line is additionally guided through the body longitudinal member (13) which is in thermal contact with the charge air line (11). [4] Motor vehicle according to claim 1, 2 or 3, characterized by , that the charge air line (11) is guided through the body longitudinal member (13) at a distance (a) from the hollow support wall, forming a passage gap (15) which preferably forms a cooling medium line. [5] Motor vehicle according to claim 4, characterized by , that the charge air line (11) passing through the body longitudinal member (13) is in thermal contact with the hollow member wall of the body longitudinal member (13), and that the body longitudinal member (13) is surrounded on the outside by cooling medium (K). [6] Motor vehicle according to claim 5, characterized by , that the charge air duct (11) is in thermal contact with the hollow beam wall via thermal bridges, in particular heat-conducting sheet metal webs (23), and that in particular the sheet metal webs (13) bridge the passage gap (15) between the charge air duct (11) and the hollow beam wall. [7] Motor vehicle according to claim 6, characterized by , that the body longitudinal member (13) has cooling fins (21) on the outside. [8] Motor vehicle according to any of the preceding claims, characterized by, that the charge air line (11) and the cooling medium line are integrated in a double pipe arrangement (26) in which the charge air line (11) runs radially inside and in which the charge air line (11) is radially outside bounded by the cooling medium line, and that the cooling medium line is formed as an annular gap (29) formed between a radially inner pipe wall (25) and a radially outer pipe wall (27). [9] Motor vehicle according to any one of the preceding claims, characterized by , that the body longitudinal member (13) is associated with a cooling system with a spray device (30) by means of which the cooling medium is sprayed onto the outer circumferential surface of the charge air line (11), forming a cooling medium film on the outer circumferential surface of the charge air line (11), and that the cooling takes place using the enthalpy of vaporization resulting from the evaporation of the cooling medium film.

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