Fuel-operated heating appliance and method for operating a fuel-operated heating appliance, in particular for a vehicle

Abstract

Fuel-operated heating appliance (10), in particular for a vehicle, comprising a burner section (12) with a combustion chamber (20), a combustion air supply arrangement (14) for supplying combustion air (L) to the combustion chamber (20), a fuel supply arrangement (16) for supplying fuel (B) to the combustion chamber (20), a control arrangement (26) for controlling the combustion air supply arrangement (14) and the fuel supply arrangement (16), and a spatial orientation sensor arrangement (34) for providing spatial orientation information related to the spatial orientation of the fuel supply arrangement (16) and / or the spatial orientation of the burner section (12) and / or the spatial orientation of the control arrangement (26), characterized in that the control arrangement (26) is configured toto control the combustion air supply arrangement (14) and / or the fuel supply arrangement (16) based on a change in the spatial orientation of the fuel supply arrangement (16) and / or the burner area (12) and / or the control arrangement (26) detected on the basis of the spatial orientation information during combustion operation in order to carry out the combustion operation of the heating appliance (10).

Description

The present invention relates to a fuel-operated heating device, in particular for a vehicle, comprising a burner area with a combustion chamber, a combustion air supply arrangement for supplying combustion air to the combustion chamber, a fuel supply arrangement for supplying fuel to the combustion chamber, a control arrangement for controlling the combustion air supply arrangement and the fuel supply arrangement, and a spatial orientation sensor arrangement for providing spatial orientation information related to the spatial orientation of the fuel supply arrangement and / or the spatial orientation of the burner area and / or the spatial orientation of the control arrangement. The combustion characteristics of such a fuel-powered heater are strongly influenced by external factors, such as the altitude of the vehicle equipped with such a heater and the ambient air pressure. A change in altitude or air pressure leads to a shift in the air / fuel ratio and thus affects pollutant emissions and the heating output achievable with a given amount of fuel. EP 1 752 323 A1 discloses a fuel-operated heater for a vehicle, comprising a burner section, a combustion air supply arrangement, and a fuel supply arrangement, wherein fuel is supplied to the burner section from the fuel supply arrangement via at least two nozzles provided on its housing. The fuel supply arrangement is controlled by a control arrangement such that a different quantity of fuel is introduced into the nozzles depending on the installation position of the burner section, a start-up operation, and / or a desired heating output. From DE 101 25 591 C1, a fuel-operated heating device for a vehicle according to the preamble of claim 1 is known, comprising a burner section, a combustion air supply arrangement, and a fuel supply arrangement, which are controlled by a control arrangement. If a sensor arrangement, comprising a position sensor, provides spatial orientation information indicating a safety-critical condition of the vehicle, the control arrangement controls the combustion air supply arrangement and / or the fuel supply arrangement in such a way that the combustion air supply or the fuel supply is interrupted in order to extinguish the flame of the heating device. The object of the present invention is to provide a fuel-operated heating device, in particular for a vehicle, and a method for operating a fuel-operated heating device, with which an improved heating characteristic can be achieved. According to the invention, this problem is solved by a fuel-operated heating appliance of the type mentioned at the outset, having the features of the characterizing part of claim 1. It has been recognized that the spatial orientation of a fuel conveying system has a significant influence on its conveying characteristics. For example, if such a fuel conveying system is positioned so that the fuel is conveyed upwards, then generally less fuel will be delivered under the same conveying conditions than with a spatial orientation in which the fuel is conveyed downwards, i.e., with the assistance of gravity.Variations in the spatial orientation of the fuel delivery system, with unchanged control characteristics, result in a changing fuel quantity being delivered in relation to an unchanged combustion air quantity. This influences the composition of the air / fuel mixture and consequently improves the efficiency of the heating appliance as well as the pollutant composition of the exhaust gases emitted from the appliance. Providing spatial orientation information makes it possible to detect changes in the spatial orientation of the fuel delivery system, for example, during driving, or to detect that parking the vehicle on steep terrain also results in a corresponding positioning of the fuel delivery system.According to the invention, this can be used to adapt the control characteristics of the fuel delivery arrangement and / or the combustion air delivery arrangement in order to take account of an influence on the delivery behavior of the fuel delivery arrangement induced by a change in spatial orientation or a detected spatial orientation. The spatial orientation of a fuel-fed section of the heating appliance, i.e., the burner section containing the combustion chamber, can also influence the combustion characteristics. In particular, when the burner section is designed as a vaporizing burner with a porous vaporizing medium that absorbs liquid fuel and distributes it through capillary action and also under the influence of gravity, the spatial orientation of the burner section affects the distribution characteristics of the liquid fuel within the internal volume of the porous vaporizing medium and thus also the evaporation of the fuel from the porous vaporizing medium to the combustion chamber. By providing spatial orientation information, especially for the burner section, or...According to the invention, the control arrangement, which is generally combined with the burner area to form a single unit, is also made possible to take this spatial position into account when controlling various system areas of the heating device, in particular the fuel supply arrangement and the combustion air supply arrangement, in order to achieve optimized combustion behavior. Not only does the spatial orientation of the fuel delivery system, which changes with the vehicle's position during operation, influence its delivery characteristics, but so too does the positioning of the fuel delivery system itself, for example, within a vehicle. Manufacturers generally specify target installation positions, but it is not guaranteed that these target positions will actually be adhered to when installing such a heating device or fuel delivery system. Since the control of the fuel delivery system...The combustion air supply arrangement, designed to provide high efficiency and low emissions from the heater, is based on the intended installation positions. However, installation in a position that deviates from these positions can lead to the heater not operating at its intended efficiency, thus failing to deliver the required heating output, and also resulting in excessively high emissions. The heater design according to the invention addresses this problem because, even if a vehicle heater or its fuel supply arrangement is not installed correctly, the spatial orientation is detected. This allows for the detection of deviations from the intended installation position, enabling compensation through appropriately adjusted control. For example, the spatial orientation sensor arrangement may include at least one spatial orientation sensor, preferably a three-axis accelerometer or a three-axis gyroscope. Such three-axis sensors make it possible to provide spatial orientation information that accurately represents the position of the fuel conveying arrangement. Since, as explained above, the positioning of the fuel delivery assembly or one of its fuel pumps is particularly critical with regard to the delivery behavior of a fuel-operated heating appliance, it is further proposed that the fuel delivery assembly include a fuel pump, wherein at least one position sensor detects the position of the fuel pump. In particular, it can be provided that the at least one position sensor is located on the fuel pump, for example, on or in a housing of the fuel pump. This design is particularly suitable when the fuel delivery assembly and, for example, the burner area or the control assembly do not form a single unit, but are, for example, integrated separately into a vehicle, so that a defined relative position of the fuel delivery assembly with respect to, for example, the burner area or the control assembly is not ensured. Particularly in an embodiment where the fuel supply arrangement forms a single unit with the burner area and, in particular, also with the control arrangement, i.e., the relative position of these assemblies to each other is fixed, the invention provides that at least one spatial orientation sensor detects the spatial orientation of the control arrangement and / or the burner area, wherein the at least one spatial orientation sensor can be provided on the control arrangement. By providing the spatial orientation information in relation to the control arrangement on the one hand, and because the control arrangement and the fuel supply arrangement have a defined relative position to each other, the spatial orientation of the fuel supply arrangement can also be inferred based on this spatial orientation information. Even with regard to the burner area or the control arrangement, the spatial orientation of the fuel supply arrangement can be determined.With a fuel supply arrangement positioned separately from the control arrangement, such a design creates the possibility of taking into account the spatial position of the burner area or the control arrangement when supplying the burner area with fuel. The present invention further relates to a method for operating a fuel-operated heating device, in particular for a vehicle with the inventive structure, according to claim 7. The present invention is described in detail below with reference to the accompanying figures. Figure 1 shows a basic representation of a fuel-operated heating appliance; Figure 2, in its representations a) and b), shows a relationship between the CO2 content and the CO content in the exhaust gases of a fuel-operated heating appliance at different installation positions of the heating appliance. In Fig. 1, a fuel-operated heating appliance is generally designated by 10. The heating appliance 10 comprises a burner section 12, into which combustion air L is supplied by a combustion air supply arrangement 14, for example, a side-channel blower. Liquid fuel B is conveyed from a reservoir 18 into a combustion chamber of the burner section 12, generally designated by 20, by a fuel supply arrangement 16, for example, a metering pump. If the burner section 12 is configured as a vaporizing burner, it is lined, at least partially, with a porous vaporizing medium. This medium absorbs the liquid fuel B, distributes it within its internal volume by capillary action, and releases the fuel in vapor form from its surface exposed to the combustion chamber 20. This creates a fuel / air mixture that can be ignited in the combustion chamber 20 by an ignition device 22, for example, a glow plug, and thus combusted.The combustion gases A leave the combustion chamber in the direction of an exhaust gas routing system. The heat generated in burner section 12 can be transferred to a medium M to be heated, for example water or air, in a heat exchanger section 24. The medium M flows through the heat exchanger section 24 and absorbs heat from the combustion gases A generated in burner section 20. The combustion air supply arrangement 14 and the fuel supply arrangement 16 are controlled by a control arrangement generally designated 26. Depending on the required heating operation, in particular the required heating output or a set heating output stage, the control arrangement 26 controls the combustion air blower 14 to supply a predetermined quantity of combustion air L, for example, such that a rotational speed of a conveying wheel 28 of the combustion air supply arrangement 14, which is assigned to a heating output stage, is reached. Similarly, the control arrangement 26 controls the fuel supply arrangement 16 to operate it to supply a quantity of fuel B, which is assigned to a set heating output stage.The fuel delivery arrangement 16, for example when configured as a metering pump, can comprise an intermittently reciprocating pump piston that is movable within a pump chamber and, with each stroke, expels a specific volume of fuel B, which has been taken up in the pump chamber, towards the combustion chamber 20. The fuel delivery arrangement 16, i.e., the metering pump, takes in the fuel from the reservoir 18 at a fuel inlet 30 and discharges it towards the combustion chamber 20 at a fuel outlet 32. The fuel inlet 30 and the fuel outlet 32 ​​can, for example, be configured as coaxially arranged connection ports that can be connected to the reservoir 18 on the one hand and the burner area 12 on the other via pipe connections. Figure 1 shows that, for example, the ignition element 22 is also connected to the control arrangement 26, so that during start-up operation, combustion can be initiated by excitation of the ignition element 22 when an ignitable mixture of combustion air L and fuel B is generated. Furthermore, an electrically excitable heating device can be provided in the burner area 12, which can heat the aforementioned porous evaporator medium to support fuel vaporization, particularly during the start-up phase. Such a heating arrangement can be controlled by the control arrangement 26. The fuel delivery characteristics of the fuel delivery assembly 16 are highly dependent on its installation position, for example, in the heater 10 or in a vehicle. If, for instance, the fuel delivery assembly 16 is configured as described, i.e., with a coaxial fuel inlet 30 and fuel outlet 32, and a pump piston that moves intermittently back and forth between them in a pump chamber, then at the same operating frequency, this fuel delivery assembly 16 will discharge more fuel when the fuel outlet 32 ​​is oriented downwards in the direction of gravity. If the fuel outlet is oriented upwards or inclined upwards, the fuel delivery assembly 16 will discharge against the force of gravity and will discharge a smaller quantity of fuel at the same operating frequency. To account for variations in the amount of fuel delivered by the fuel delivery assembly 16 that depend on the installation position and thus the spatial orientation, a defined installation position is generally provided for the fuel delivery assembly 16, for example, such that the fuel outlet 32 ​​is inclined upwards at an angle of 15° to 35° with respect to a horizontal line. While installation positions with an angle of inclination greater than 35° are also permissible in principle, the installation position or inclination of the fuel outlet 32 ​​should ideally be within the aforementioned angle range of 15° to 35°, as this ensures that the amount of fuel intended for a given heating output level is actually delivered when the fuel delivery assembly is activated to operate, for example, at a specific operating cycle frequency. In principle, when integrating a vehicle heater 10 or its fuel supply assembly 16 into a vehicle, it cannot be assumed that the manufacturer's specified installation position, particularly for the fuel supply assembly 16, will be adhered to. The risk of deviations is especially high if the fuel supply assembly 16 is not integrated into the vehicle as a single unit with the remaining system components of the heater 10, but rather separately and, for example, installed in a different position within the engine compartment. Even if the fuel supply assembly 16 is integrated into the vehicle as a single unit with the other system components of the heater 10, it cannot be ruled out that the entire heater 10 will be installed in such a way that it, and in particular the fuel supply assembly 16, assumes an installation position that deviates significantly from the specified position.Even during vehicle operation, it is generally possible that the fuel supply arrangement 16 may deviate from its intended installation position due to the vehicle's tilt. This intended installation position is defined by a coordinate system in which, for example, a vertical direction (i.e., the direction of gravity) is specified, and a horizontal direction is orthogonal to it. For instance, when installed in a camper van, if the vehicle is parked on a steep slope and the heater 10 is used as a parking heater, the fuel supply arrangement 16 may operate in such a spatial position, deviating from its intended installation position and thus its intended spatial orientation, for an extended period of time.A quantity of fuel B that deviates significantly from the target quantity in relation to the quantity of combustion air L supplied to the combustion chamber 20 leads to the combustion no longer being able to take place at the optimal ratio of air to fuel, with the risk of excessive pollutant emissions or also the risk of deposits forming in the area of ​​the combustion chamber 20 or the burner area 12 in general. Figures 2a and 2b show the ratio of CO2 content to CO content in the combustion gases for different installation positions of a vehicle heater and thus also different spatial orientations of the fuel supply assembly associated with this heater. In these different installation positions, the vehicle heater in Figure 2a, which is integrated with the fuel supply assembly, was oriented horizontally, while in Figure 2b, the orientation was vertical, i.e., at an angle of 90° to the installation position in Figure 2a. It is clearly evident that the minimum CO content is approximately 200 ppm in the case of horizontal installation, while it is approximately 260 ppm in the case of vertical installation. Since the CO content in the exhaust gas should generally be minimized, the installation position in Figure 2b, and the resulting spatial orientation of the fuel supply assembly, would be unsuitable for minimizing the CO content.The spatial orientation of the heating unit 10, or more specifically its burner section 12, also has a similar influence on the combustion behavior and thus the exhaust gas composition. The installation position, particularly of the burner section 12, affects the fuel feed into it and the fuel distribution within its combustion chamber. Especially when the burner section 12 is designed as a vaporizing burner with a porous vaporizing medium that absorbs the liquid fuel, a variation in its installation position leads to a change in the influence of gravity on the distribution behavior, which in turn results in a corresponding change in the evaporation rate and the surface areas where evaporation primarily occurs. To counteract the problem of variations in the spatial orientation of the heating device 10 or a fuel supply arrangement 16, for example due to an installation position or a spatial orientation that changes during the operation of a vehicle, a spatial orientation sensor arrangement, generally designated 34, is provided in the inventive design of a heating device 10. This includes, for example, a spatial orientation sensor 36, which can be configured, for example, as a three-axis accelerometer or a three-axis gyroscope. Such a spatial orientation sensor emits a sensor signal indicating its spatial orientation.If, for example, the position sensor 36 is arranged such that it can detect the position of the fuel conveying assembly 36, for example by integration onto or into a housing of the fuel conveying assembly 16, then the output signal of the position sensor 36 directly provides position information which also indicates the position of the fuel conveying assembly 16. If, as also indicated in Fig. 1, a position sensor 36' is provided alternatively or additionally in association with the control assembly 26, for example integrated into it, and if, furthermore, the fuel conveying assembly 16 is provided as a unit with the heating device 10 and, in particular, also with the control assembly 26, then the position of the heating device 12, which is installed with it in a defined manner, and thus also the position of the fuel conveying assembly 16, can be inferred from the position of the control assembly 26 detected by the position sensor 36' and thus also the position of the fuel conveying assembly 16.This means that providing a spatial orientation sensor 36' in association with the control arrangement 26 is particularly advantageous when the control arrangement 26, together with the fuel supply arrangement 16 and, for example, other components of the heater 10, is designed as a single unit with a defined relative positioning. If the fuel supply arrangement 16 is separate from the remaining system areas of the heater 10, for example, to be installed in a different position within a vehicle, then assigning a spatial orientation sensor 36 directly to the fuel supply arrangement 16 is advantageous. Regardless of whether the fuel supply arrangement 16 is combined with the heater 10 or the burner area 12 to form a single unit, assigning the spatial orientation sensor 36' to the control arrangement 26 has the advantage that influences on the combustion behavior caused by the spatial orientation of the heater 10 are also detected.The pollutant composition can be compensated for, since the spatial orientation of the control arrangement 26 also reveals the spatial orientation of the other components of the heating device 10, which are combined into a single unit, particularly the burner section 12. Assigning the spatial orientation sensor 36' to the control arrangement 26 is particularly advantageous, as it eliminates the need for additional wiring connections. However, such a spatial orientation sensor 36' could also be located elsewhere, especially within the burner section 12. Based on the spatial orientation information of the fuel supply arrangement 16 represented by the output signal of such a spatial orientation sensor 36 or 36', the control arrangement 26 can, during combustion operation of the heating appliance 10, control the fuel supply arrangement 16 and / or the combustion air supply arrangement 14 in such a way that, for a given combustion operation, i.e., a given heating output level, an optimal fuel / combustion air mixture can actually be provided with regard to the energy that can be released on the one hand and with regard to minimizing pollutant emissions on the other. Here, for example, a characteristic map can be generated based on mathematical models or laboratory tests, which can be assigned to different heating outputs or...The heating output levels and, in relation to different spatial positions of the fuel supply assembly 16, contain information on how the fuel supply assembly 16 is to be controlled and / or how the combustion air supply assembly 16 is to be controlled. For example, a basic value for the fuel supply rate or the supply operation, i.e., the operating cycle frequency, of the fuel supply assembly 16 can be specified for a target installation position and thus a target spatial position. Depending on the deviation from this target spatial position, a correction is made, for example, increasing the fuel supply rate (i.e., increasing the operating cycle frequency) or decreasing it. For example, deviation ranges can be defined, and a correction of the control measure specified for the target range can be assigned to each of these deviation ranges.Corresponding corrective measures can also be provided for the combustion air supply arrangement 14. According to the invention, a change in the supply characteristics of the fuel supply arrangement 16 due to its spatial orientation can also be compensated for by appropriately adjusting the quantity of combustion air supplied. Furthermore, according to the invention, it is also possible to adjust both the control of the combustion air supply arrangement 14, for example to provide an adapted rotational speed of the impeller 28, and the control of the fuel supply arrangement 16, for example to provide an adapted operating cycle frequency of an intermittently reciprocating pump piston. Finally, it should be noted that, for the purposes of the present invention, the spatial orientation of the fuel delivery arrangement is defined by its orientation at a specific location, for example, in a Cartesian coordinate system. This is independent of the fact that, for example, moving a vehicle to different altitudes also changes the altitude of the metering pump, which, however, does not necessarily entail a change in the spatial orientation of the metering pump. For example, if the roadway is positioned at different altitudes on a horizontal surface, a metering pump provided in such a vehicle will indeed have different altitudes or positions, but will have the same spatial orientation at each respective altitude.

Claims

Fuel-operated heating appliance (10), in particular for a vehicle, comprising a burner section (12) with a combustion chamber (20), a combustion air supply arrangement (14) for supplying combustion air (L) to the combustion chamber (20), a fuel supply arrangement (16) for supplying fuel (B) to the combustion chamber (20), a control arrangement (26) for controlling the combustion air supply arrangement (14) and the fuel supply arrangement (16), and a spatial orientation sensor arrangement (34) for providing spatial orientation information related to the spatial orientation of the fuel supply arrangement (16) and / or the spatial orientation of the burner section (12) and / or the spatial orientation of the control arrangement (26), characterized in that the control arrangement (26) is configured toto control the combustion air supply arrangement (14) and / or the fuel supply arrangement (16) based on a change in the spatial orientation of the fuel supply arrangement (16) and / or the burner area (12) and / or the control arrangement (26) detected on the basis of the spatial orientation information during combustion operation in order to carry out the combustion operation of the heating appliance (10). Heating device (10) according to claim 1, characterized in that the spatial orientation sensor arrangement (34) comprises at least one spatial orientation sensor (36, 36'), preferably a three-axis accelerometer or three-axis gyroscope sensor. Heating appliance (10) according to claim 2, characterized in that the fuel supply arrangement (16) comprises a fuel pump, wherein at least one spatial orientation sensor (36) detects the spatial orientation of the fuel pump. Heating device (10) according to claim 3, characterized in that the at least one room position sensor (36) is provided on the fuel pump. Heating device (10) according to one of claims 2 to 4, characterized in that at least one spatial orientation sensor (36') detects the spatial orientation of the control arrangement (26) and / or the spatial orientation of the burner area (12). Heating device (10) according to claim 5, characterized in that the at least one room position sensor (36') is provided on the control arrangement (26). Method for operating a fuel-operated heating appliance (10), in particular for a vehicle, according to one of the preceding claims, wherein the fuel supply arrangement (16) is controlled to adjust the amount of fuel supplied to the combustion chamber (20) based on a change in the spatial orientation of the fuel supply arrangement (16) and / or the burner area (12) and / or the control arrangement (26) detected during combustion operation on the basis of spatial orientation information, or / and wherein the combustion air supply arrangement (14) is controlled to adjust the amount of combustion air supplied to the combustion chamber (20) based on a change in the spatial orientation of the fuel supply arrangement (16) and / or the burner area (12) and / or the control arrangement (26) detected during combustion operation on the basis of spatial orientation information, for the purpose of carrying out the combustion operation of the heating appliance (10).

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