MOTOR VEHICLE WITH TEMPERATURE-CONTROLLED DEVICE

Abstract

A motor vehicle has a passenger compartment (1) and a passenger compartment ventilation system for extracting air (12) from the passenger compartment, which is in thermal contact with a vehicle component (2) that absorbs heat during the operation of the vehicle.

Description

[0001] The present invention relates to a motor vehicle with a device whose temperature must be regulated or at least influenced during operation.

[0002] DE-OS 26 03 297 describes a motor vehicle with a passenger compartment and a passenger compartment ventilation for discharging air from the passenger cell, in which devices which heat up during operation due to solar radiation or waste heat from an internal combustion engine, in particular a tank or an exhaust system, are cooled by thermal contact with the passenger compartment ventilation.

[0003] An object of the invention is to provide a new application for such a motor vehicle with passenger compartment ventilation.

[0004] Since this document was published, vehicles with alternative drive systems have emerged in which components absorb rather than release heat during operation. And operating temperatures that are too low rather than too high can become a problem. For example, the fuel contained in the tanks of compressed gas-powered vehicles must first change from a liquid to a gaseous state before it can be extracted. The energy required for this process is extracted from the tank contents, causing them to cool. Adiabatic cooling also occurs when gas is siphoned from a high-pressure tank without changing its state. Hydrogen tanks used to supply fuel cells often contain a solid, typically granules made of a metal alloy, in which the hydrogen is soluble in large quantities. In order to release the hydrogen again, the tank must absorb heat energy.

[0005] Contrary to the teaching of DE-OS 26 03 297, in a motor vehicle with a passenger compartment and a passenger compartment ventilation for discharging air from the passenger cell, the passenger compartment ventilation can also be used to control the temperature of components which absorb heat during operation, in particular a tank containing a high-density gas such as an LPG tank or hydrogen tank, in which the release of the gas has a cooling effect during operation, which therefore does not require the cooling by exhaust air taught in the prior art.

[0006] A preferred application of the invention is a hydrogen tank for powering a fuel cell. If the tank contains a storage metal, the cooling that occurs when hydrogen is released from it also reduces the release rate, so that excessive cooling must be prevented to maintain fuel cell performance. Tanks that store gaseous hydrogen under high pressure often have a plastic composite shell to minimize weight. Here, too, heat input via the passenger compartment vent is useful to prevent cooling that could lead to embrittlement of the composite material.

[0007] The motor vehicle may have an air conditioning system for heating or cooling the passenger compartment. If the air conditioning system is in heating mode and the exhaust air from the passenger compartment is warmer than the ambient air, it is obvious that the component to be heated can be heated more effectively through thermal contact with the passenger compartment ventilation than through contact with ambient air.

[0008] In order to prevent the vehicle component from becoming too cold even when the vehicle is not in use and therefore no heat is normally available from the passenger compartment, a heater can be provided for the vehicle component that is automatically activated when the temperature falls below a switch-on temperature. This heater can be implemented by the air conditioning system mentioned above or another type of passenger compartment heater that is automatically activated when the vehicle is stationary in a cold environment, thus ensuring that warm air is available that can be supplied to the vehicle component via the passenger compartment ventilation. However, it is more efficient for the heater to act on the vehicle component without passing the passenger compartment, e.g. through a coolant circuit that transports waste heat from the fuel cell to the vehicle component, or through an electric heating element arranged in close thermal contact with the vehicle component.The latter can be operated with electrical energy from the fuel cell or from a source external to the vehicle, depending on availability.

[0009] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. They show: Fig. 1 is a schematic view of a motor vehicle according to the invention; and Fig. 2 a block diagram of thermal components in a vehicle according to the invention

[0010] Fig. 1 shows a motor vehicle with a passenger compartment 1 and with hydrogen tanks 2 arranged behind the passenger cell, which have a Fig. 2 feed the fuel cell designated 6, so that it supplies electrical energy for the operation of a drive motor of the vehicle.

[0011] The tanks can contain a storage metal filling in which the hydrogen is dissolved. The lower the temperature, the slower the hydrogen release. If, during periods of high consumption, the cooling can no longer be compensated by external heat, this leads to a weakening of the hydrogen flow and thus a reduction in available power.

[0012] This can become a problem when driving at low ambient temperatures, especially if, as here, the tanks 2 are still surrounded by a protective housing 3, the closed walls of which prevent close thermal contact between the tanks and the environment due to the wind flowing past the tanks 2.

[0013] According to another technique, the hydrogen is stored in the tank as a gas. The tank must therefore offer high pressure resistance while remaining lightweight. Composite plastic systems used for this purpose tend to become brittle at low temperatures. Fluctuating pressure loading at low temperatures can therefore affect the service life of such tanks. Therefore, it is important to prevent overcooling in such tanks as well.

[0014] For this purpose, a passage 4 to the housing 3 is provided in a lower area of ​​a rear wall of the passenger compartment 1, through which warm exhaust air from the passenger compartment 1 is guided into the housing. On its way to an outlet 5 at the upper end of the housing 3, the warm air passes the tanks 2 and transfers its heat to them.

[0015] Fig. 2 shows components of a motor vehicle relevant for the temperature control of the hydrogen tanks 2 according to a further developed embodiment in a block diagram, wherein already with reference to Fig. 1 described components in Fig. 2 are provided with the same reference numerals and will not be described again.

[0016] A heater 7 is provided in a manner known per se to heat a fresh air stream 8 to a desired temperature before it enters the passenger compartment 1. The heater 7 here comprises a cooler 9, which receives waste heat from the fuel cell 6 via a cooling water circuit driven by a pump 10 and releases it to the ambient air, and a passage 11 with a controlled cross-section, through which a portion of the air heated at the cooler 9 enters the passenger compartment 1 as a fresh air stream 8. As fresh air flows in via the heater 7, exhaust air 12 flows through the passage 4 to the housing 3 and heats the tanks 2.

[0017] A control unit 13 is connected to a temperature sensor 14 on one of the tanks 2 to detect any heat demand and control the fresh air flow 8 accordingly. If the tank is a high-pressure tank made of composite plastic as described above, the control unit 13 can be configured to detect the heat demand when a threshold temperature below 0°C is exceeded, below which the plastic is at risk of becoming brittle, and impacts to which the tank is exposed during travel could lead to premature aging of the material.

[0018] A further temperature sensor 12 is conventionally provided on the fuel cell 6 to control the pump 10 based on the temperature of the fuel cell 6. Here, the temperature sensor 12 of the control unit 13 also serves to assess, when the vehicle is stationary, whether residual heat is still present in the fuel cell 6 and, if necessary, to operate the pump 10 and the heater 7 to supply this heat to the passenger compartment 1 and ultimately to the tanks 2.

[0019] Alternatively, a branch of the cooling water circuit could be led through the housing 3 and the control unit 13 could be configured to supply this branch with cooling water from the fuel cell in order to heat the tanks 2 while bypassing the passenger compartment.

[0020] If there is a heat requirement at the tank 2, but no residual heat is available in the fuel cell 6, the control unit 13 can be configured to start up the fuel cell 6 when the vehicle is stationary, to store the electrical energy generated in a battery 16 and to use the waste heat to keep the tanks 2 warm as described above.

[0021] Such a mode of operation becomes inefficient at the latest when the storage capacity of the battery 16 is exhausted. Therefore, an electrical heating element is provided as an additional heating means 17 for the tanks 2. The heating element can be Fig. 2, in order to heat the tanks 2 with minimal losses. When the control unit 13 operates the heater 17 with power from the battery 16, the battery is gradually discharged again, and, if necessary, a further phase can follow in which the fuel cell 6 is operated while the vehicle is stationary.

[0022] The stationary vehicle can, of course, be connected to an external charging station to charge the battery 16 without using the fuel cell 6. If this is the case, the control unit 13 can satisfy a heat demand of the tanks 2 by connecting the heater 17 to the charging station via a switch 18.

[0023] The control unit 13 may be connected to a warning signal generator to remind a user to connect the vehicle to a charging station when the ambient temperature is low, to ensure that no hydrogen from the tanks needs to be used to keep the tanks 2 warm. Reference symbol 1 passenger compartment 2 tanks 3 housings 4th round 5 Outlet 6 Fuel cell 7 Heating 8 Fresh air flow 9 coolers 10 Pump 11 controlled passage 12 Exhaust air 13 Control unit 14 Temperature sensor 15 Temperature sensor 16 Battery 17 Heating 18 switches QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE-OS 26 03 297 [0002, 0005]

Claims

[1] Motor vehicle with a passenger compartment (1) and a passenger compartment ventilation for discharging air from the passenger cell, characterized by that the passenger compartment ventilation is in thermal contact with a vehicle component that absorbs heat during vehicle operation. [2] Motor vehicle according to claim 1, wherein the vehicle component which absorbs heat during operation is a fuel tank (2) which contains a high-density gas as fuel. [3] Motor vehicle according to claim 2, wherein the fuel tank (2) has a shell made of plastic composite material. [4] Motor vehicle according to claim 2 or 3, further comprising a fuel cell (6) fed by the fuel. [5] Motor vehicle according to one of the preceding claims, further comprising an air conditioning system for heating or cooling the passenger compartment. [6] Motor vehicle according to one of the preceding claims, further comprising a heater (7, 17) for the vehicle component which is automatically activated when a switch-on temperature is undershot, wherein the switch-on temperature is optionally below 0°C. [7] Motor vehicle according to claim 6, wherein the heater (7, 17) is fed by at least two energy sources selected from externally supplied electrical energy, electrical energy generated by the fuel cell (6) and waste heat generated by the fuel cell (6).

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