DE102021112550A1 - Mobile heating device and method for operating a mobile heating device - Google Patents

Abstract

The invention relates to a mobile heating device (100), in particular a mobile vehicle heating device, comprising - a heater assembly (1) with a combustion chamber (9) and - a fuel supply line (4) for supplying liquid fuel to the heater assembly (1), the heater assembly (1) in particular an evaporator receptacle assembly for evaporating liquid fuel, comprising an evaporator receptacle body (2) for accommodating an evaporator element (2) for distributing and evaporating liquid fuel, the fuel supply line (4) comprising a supply pipe (5) with an inlet (14) for inputting fuel and an outlet (16) for discharging fuel to the combustion chamber (9), the fuel feed line (4) further having an emptying device (10) for partially or completely emptying the fuel feed line (4) through the outlet (16). the invention describes a method for operating a mobile heating device.

Description

The invention relates to a mobile heating device with a fuel supply line and a method for operating a mobile heating device.

Burners, in particular evaporator burners, are used in particular in auxiliary and/or auxiliary heaters operated with liquid fuel, in particular for vehicles. In such evaporative burners, liquid fuel is introduced into an evaporator via a fuel supply line. As an evaporator itself z. B. metal fiber fleeces can be used. In particular, the vaporizer imbibes liquid fuel via capillary action and disperses liquid fuel. Liquid fuel is vaporized and ignited by means of the heat provided by a glow plug or an ignition element, so that the fuel can be burned with the supply of air. For this purpose, air supply openings are arranged in a peripheral wall. Such an arrangement is, for example, from DE 10 2018 111 636 A1 known.

the DE 10 2018 104 517 discloses a combustion air fan, in particular for a side channel fan for a fuel-operated vehicle heater, comprising a fan housing, with an air flow space through which the combustion air to be transported is formed being formed in the fan housing and air flowing into the air flow space via an entry area flowing to a delivery area comprising a delivery wheel, with At least one hydrocarbon storage element for storing gaseous hydrocarbons present in the air flow space is arranged in the air flow space. The purpose of the hydrocarbon reservoir is to ensure that when the vehicle heating device and a correspondingly deactivated combustion air blower are deactivated, hydrocarbons are absorbed and thus do not escape to the outside as unburned fuel.

the DE 10 2004 041 202 C5 discloses a method for switching off a motor vehicle heater, which is intended to prevent the development of smoke and unpleasant odors when the vehicle heater is started. In this case, a fuel in the fuel line is heated when the metering pump is switched off and burned off during an early burn-out phase. A heating coil provided in the fuel supply is proposed for heating.

From the DE 10 2014 103 815 A1 an evaporator burner for a mobile heater is known. The evaporator has a carrier body made of a non-porous material, which comes into contact with liquid fuel on a side facing the combustion chamber. This page is a fuel preparation interface. The fuel processing surface has a surface structure. The surface structuring of the fuel processing surface can include, for example, elongated grooves and elevations as rib-like projections. The fuel processing surface can be arranged both perpendicularly and parallel to a bottom side of the evaporator receptacle.

the DE 8403269 U1 discloses using a wire-shaped throttle in a supply line of a heater with a combustion chamber. Such a throttle is formed by a smooth wire and serves in particular to reduce a remaining cross-section of the supply line and thus to increase the flow rate during operation and to avoid the formation of vapor bubbles.

The object of the invention is to specify an improved mobile, fuel-operated heating device and to specify a method for operating a mobile heating device. In particular, undefined states should be avoided during the operation and idle phase of the heating device.

The object of the invention is achieved by the features of claim 1 with regard to the mobile heating device and by the features of claim 14 with regard to the method. Appropriate configurations result from the respective dependent claims.

The mobile heating device according to the invention comprises a heater assembly with a combustion chamber and a fuel supply line. The fuel supply line is suitable for supplying fuel to the heater assembly, in particular to its combustion chamber. The fuel supply line includes a supply tube having an inlet for inputting fuel and an outlet for discharging fuel to the combustor. The fuel supply line also includes an emptying device for partially or completely emptying the fuel supply line through the outlet. The fuel supply line can be emptied by means of the emptying device, in particular at the end of the heating process when no more fuel is supplied through the inlet. Thus, the fuel supply line is put into a state in which uncontrolled emptying is avoided for a rest state. Thus, on the one hand, an evaporative emission, in particular an evaporative emission of hydrocarbons, is avoided and smoke development or odor nuisance when the heating device is started again is avoided. The supply pipe can be straight or curved or act with bends provided pipe. The emptying device is designed in particular in such a way that it has no function with a typical fuel flow during normal operation of the heating device and only develops a function when an upstream fuel flow is shut off.

The heating device can in particular be a heating device with an evaporator burner. In this embodiment, the heater assembly includes an evaporator receptacle assembly for evaporating liquid fuel. The evaporator receptacle assembly includes an evaporator receptacle body for accommodating an evaporator element for diffusing and evaporating liquid fuel.

The heating device can be a vehicle heating device.

An evaporator element can, for example, have or consist of a metal grid, a fleece made of metal and/or rock fibers and/or a porous material. Such materials effectively provide a large surface area for liquid fuel to vaporize. The evaporator receiving body has a bottom area and a peripheral wall with a plurality of air supply openings. In particular, the air supply openings can be arranged in one or more rows in a peripheral wall.

A receptacle for a glow plug is expediently provided in the evaporator receptacle body, by means of which the vaporized fuel can be ignited. This glow plug or the heat release and heat conduction caused by the combustion process also serves as a heat source, which also heats the fuel flowing through the fuel feed line.

The emptying device expediently comprises a nucleation device which comprises at least one rough and/or structured nucleation surface for the formation of boiling bubbles. The rough and/or structured nucleation surface comprises, in particular, elevations and/or depressions with a height of at least 0.006 mm. The rough and/or structured nucleation surface causes gas bubbles to form heterogeneously from the liquid fuel, in particular from the low-boiling fuel fractions. This function is only achieved when the flow rate of the fuel is reduced compared to a functional state of the heating device due to a longer dwell time of the fuel on the nucleation surface (at a given temperature). Due to the longer residence time, the fuel heats up to a higher temperature than during normal operation, so that gas bubbles can form. For this purpose, in particular, a burnout can take place after the fuel flow has been shut off upstream, in which case a combustion air fan of the heater assembly continues to be operated and remaining fuel as well as fuel that is subsequently expelled continues to be burned. The gas bubbles also push liquid parts of the fuel out of the fuel feed line, so that the fuel feed line is at least partially emptied.

In one configuration, the nucleation device can be designed as a separate component which is interposed between two sections of the fuel supply line or is designed as an outlet of the fuel supply line. For example, the nucleation device can be a component which is arranged between two feed pipe sections.

In one embodiment, the nucleation surface is arranged on an inner lateral surface of the feed pipe and/or on an inner surface of a connecting piece arranged at the inlet of the feed pipe. The nucleation surface extends in particular over the entire inner lateral surface of the feed pipe. Alternatively, the nucleation surface can also be arranged only in a partial area of the inner lateral surface, for example in an area of the feed pipe close to the inlet. For this purpose, for example, ribs can also be placed on the inner lateral surface and/or jumps in the cross section of the feed pipe can be provided. The nucleation surface expediently extends at least over a length of at least 0.3 cm, in particular at least 0.5 cm, in particular at least 0.8 cm, along the flow direction of the fuel. The degree of emptying of the fuel supply line can be controlled via the positioning of the nucleation surface in the fuel supply line, in particular in the supply pipe or connecting piece, since the nucleation surface is used for emptying in the area of the nucleation surface and downstream of the nucleation surface. The nucleation surface expediently extends in sections or entirely along the entire circumference of the feed pipe in the circumferential direction. The nucleation surface can be formed as one or more disturbances, e.g.

The optionally provided connecting piece is in particular provided with a non-return valve, for example in the form of a pressure-limiting valve or overpressure relief valve, in order to prevent unintentional outflow of fuel. Continue a shut-off device and/or suck-back device can be provided in the fuel feed line, preferably upstream of the feed pipe

The nucleation surface is arranged, in particular, in a close-up area to the exit, with the close-up area being in particular a maximum of 1.10 m, in particular a maximum of 1 m, in particular a maximum of 0.9 m away from the exit. The outlet itself can be an area in which the fuel supply pipe is permanently or detachably connected to the actual heating device, in particular a wall of the combustion chamber or an evaporator receiving body. A fixed connection is in particular a welded connection. For an alternative detachable connection, a connecting piece, a quick-release fastener or a screw cap can be provided at the outlet of the fuel supply line.

In a further embodiment, a further element is arranged in the fuel feed line, in particular in the feed pipe, which element has the nucleation surface alternatively or additionally as a further nucleation surface. The further element is designed in particular as a displacement wire. Such a displacement wire is basically used to reduce a cross section of the fuel feed line and thus to increase a flow rate of the fuel when the heating device is switched on. Due to the nucleation surface on the displacer wire, at least partial emptying of the fuel supply line can be achieved upon completion of the heating process. In particular, the wire can be a flat wire, i.e. flattened round wire, roughened wire, wire with grooves or notches, knurled wire, polygonal wire, shaped wire, chemically or electrochemically treated wire, e.g., etched wire or coated wire.

The nucleation surface is expediently produced by means of mechanical deformation and/or by applying a coating and/or by means of milling and/or by means of an etching process. It is therefore, for example, a mechanically or chemically roughened surface. The nucleation surface can be provided with grooves or notches, which in particular have been introduced mechanically. The nucleation surface can be produced by direct treatment of the surface to be roughened or indirectly by deformation, in particular of the displacement wire, in which cracks are produced in a targeted manner on a lateral surface or surface. Furthermore, as described above, it can be a knurled wire or a polygonal wire, e.g. star-shaped wire. The structures can be regular or irregular structures.

In one configuration with a separate component which is connected to the fuel feed line, the component therefore has an input which is connected to a first section of the fuel feed line, in particular a first feed pipe. Furthermore, the component has an outlet which is connected to a second section of the fuel feed line, in particular a second feed pipe. The first and second sections of the feed pipe are thus fluidly connected by the component. The component can in particular be a shell-shaped housing which is preferably at least partially cylindrical. An inner surface of the component can serve as a nucleation surface. Alternatively or additionally, one or more bodies can be arranged in the component, which are preferably made of glass or ceramic and/or are present in the form of small plates, rods, sleeves, tubes, beads and/or stones. The nucleation surface can thus include the surface or lateral surface of the body. Alternatively or additionally, the bodies can be part of the further element described above.

Alternatively or additionally, the emptying device can comprise a heat supply element which is arranged on an outer lateral surface of the feed pipe and/or on an outer surface of a connecting piece arranged at the inlet of the feed pipe. The temperature is increased by the supply of heat, and thus the heterogeneous and homogeneous nucleation of boiling bubbles is facilitated.

In an alternative, the heat supply element comprises an active heating element, for example in the form of a heating sleeve.

In a further embodiment, the fuel supply line for supplying fuel to the heating device is designed to run from a fuel source to the heating device and has a first and a second zone. The fuel feed line in the first zone has a suction device that includes a fuel reservoir, the suction device being designed to suck fuel from the second zone, in particular completely, back into the first zone by means of a change in volume of the fuel reservoir. In particular, the fuel feed pipe of the above embodiments is arranged exclusively in the second zone of the fuel feed line.

The fuel reservoir is suitably at least one cavity and min at least one movable piston is formed in such a way that the fuel sucked back from the second zone can be at least partially accommodated in the fuel reservoir. For this purpose, the suck-back device expediently has an actuator, in particular with a servomotor or binary switching device for changing the volume of the fuel reservoir.

Alternatively, the fuel reservoir is formed by at least one deformable feed line section, which is preferably arranged serially in the fuel feed line, such that the fuel sucked back from the second zone can be at least partially accommodated in the fuel reservoir. In this case, the deformable supply line section can comprise a shape memory device and/or a piezoelectric switching device.

In one embodiment, the suck-back device comprises a controller or is connected to one. The controller is particularly suitable for dampening or suppressing any overshooting of the system during fuel recirculation

In another or additional alternative, the heat supply element comprises a passive thermally conductive element, which conducts heat from a heat source to the outer jacket surface or outer surface. The passive thermally conductive element can in particular comprise or be a hose clamp.

The fuel feed line, in particular the fuel feed pipe, is connected to the evaporator receiving body, expediently welded to the evaporator receiving body.

1. a) Einleiten der Beendigung eines Heizvorgangs,
2. b) Beenden einer Brennstoffzufuhr durch den Eingang des Zuleitungsrohrs,
3. c) Nach Schritt b), Bildung von Siedeblasen im Brennstoff, insbesondere an einer Nukleationsoberfläche, und Überführen zumindest eines Teils des in der Brennstoffzuleitung befindlichen Brennstoffes mittels der Siedeblasen in die Brennkammer,
4. d) Abbrennen des überführten Teils des Brennstoffes in der Brennkammer.

The method according to the invention for operating a mobile heating device, in particular for a heating device with an evaporator-type combustor, in which a fuel supply line of the heating device is completely or partially emptied, the heating device having a supply pipe with an inlet for introducing fuel and an outlet for discharging fuel a combustor, the method comprising the steps of:

1. a) initiating the termination of a heating process,
2. b) terminating a fuel supply through the inlet of the supply tube,
3. c) After step b), formation of boiling bubbles in the fuel, in particular on a nucleation surface, and transfer of at least part of the fuel in the fuel feed line into the combustion chamber by means of the boiling bubbles,
4. d) Burning off the transferred part of the fuel in the combustion chamber.

The method is particularly usable with the above heating device.

• Rücksaugen von in einer zweiten Zone der Brennstoffzuleitung verbliebenem Brennstoff in eine erste Zone der Brennstoffzuleitung, durch eine Volumenänderung eines Brennstoffreservoirs, das in der ersten Zone der Brennstoffzuleitung angeordnet ist, sowie optional nach dem Rücksaugen
• Einleiten eines weiteren Heizvorgangs mit der Heizvorrichtung;
• Ausschieben des Brennstoffs aus dem Brennstoffreservoir in die Brennstoffzuleitung; und
• Abbrennen zumindest eines Teils des ausgeschobenen Brennstoffes, insbesondere des ganzen ausgeschobenen Brennstoffes.

The method can also include the following steps, in particular:

• sucking fuel remaining in a second zone of the fuel supply line back into a first zone of the fuel supply line, by a volume change of a fuel reservoir arranged in the first zone of the fuel supply line, and optionally after the sucking back
• initiating a further heating process with the heating device;
• expelling the fuel from the fuel reservoir into the fuel supply line; and
• Burning off at least part of the fuel that has been pushed out, in particular all of the fuel that has been pushed out.

• 1 Verdampferaufnahmeanordnung in einer ersten Ausgestaltung,
• 2 Explosionszeichnung einer Verdampferaufnahmeanordnung,
• 3 Querschnitt durch ein Rohr mit einer Nukleationsfläche an der Mantelinnenfläche,
• 4a Querschnitt durch ein Rohr mit einer Nukleationsfläche an einem zusätzlichen Element,
• 4b Querschnitt durch ein Rohr mit einem zwischengeschalteten Bauteil mit Nukleationsoberfläche,
• 5 Beispiele von Oberflächenmodifikationen,
• 6 Verdampferaufnahmeanordnung in einer zweiten Ausgestaltung,
• 7 Verdampferaufnahmeanordnung in einer dritten Ausgestaltung,
• 8 Heizvorrichtung, und
• 9 Verfahrensablauf
• 10 ein Ausführungsbeispiel einer Brennstoffzuleitung mit einer Rücksaugvorrichtung,
• 11 das Ausführungsbeispiel gemäß 1, mit vergrößertem Brennstoffreservoir der Rücksaugvorrichtung und entleerter zweiter Zone der Brennstoffzuleitung,
• 12 ein weiteres Ausführungsbeispiel einer Brennstoffzuleitung mit einer seriell bzw. in-line angeordneten Rücksaugvorrichtung,
• 13 das Ausführungsbeispiel gemäß 12, mit vergrößertem Brennstoffreservoir der seriell angeordneten Rücksaugvorrichtung und entleerter zweiter Zone der Brennstoffzuleitung, und
• 14 ein Ausführungsbeispiel eines Systems umfassend eine Brennstoffzuleitung mit einem Hochtemperaturbereich und einem Niedertemperaturbereich.

The invention is explained in more detail below, also with regard to further features and advantages, on the basis of the description of exemplary embodiments and with reference to the accompanying drawings. They each show in a principle sketch:

• 1 Evaporator receiving arrangement in a first embodiment,
• 2 Exploded view of an evaporator pickup assembly,
• 3 Cross-section through a tube with a nucleation surface on the inner surface of the shell,
• 4a cross-section through a tube with a nucleation surface on an additional element,
• 4b Cross-section through a pipe with an intermediate component with a nucleating surface,
• 5 examples of surface modifications,
• 6 Evaporator receiving arrangement in a second embodiment,
• 7 Evaporator receiving arrangement in a third embodiment,
• 8th heater, and
• 9 procedure
• 10 an embodiment of a fuel supply line with a suction device,
• 11 the embodiment according to 1 , with enlarged rear fuel reservoir suction device and emptied second zone of the fuel supply line,
• 12 a further exemplary embodiment of a fuel supply line with a serially or in-line arranged suck-back device,
• 13 the embodiment according to 12 , with enlarged fuel reservoir of the serially arranged suction device and emptied second zone of the fuel feed line, and
• 14 an embodiment of a system comprising a fuel supply line with a high-temperature area and a low-temperature area.

1 12 shows an evaporator receiving arrangement as part of a heating device 100 in a first embodiment. The evaporator receiving arrangement comprises an evaporator receiving body 2 and a section of the fuel supply line 4. The evaporator receiving body 2 is designed to receive an evaporator element 3 for distributing and evaporating liquid fuel. An evaporator element 3 can be formed of, for example, a metal mesh or a porous material with a large surface area. The evaporator receiving body 2 has a base area 6 and a peripheral wall 8 with a plurality of air supply openings 41 . The air supply openings 41 can be arranged in particular in a peripheral wall 8 in one or more rows.

The evaporator element 3 can, as shown in the exploded view in 2 shown, are inserted and fastened into the evaporator receiving body 2 by means of a fastening element 40 .

A recess 42 for a glow plug is also provided in a peripheral wall 8 of the evaporator receiving body 2 .

The fuel feed line 4 comprises a feed pipe 5. In this case, the fuel feed line 4 and the feed pipe 5 can be integrally or cohesively connected to one another in one exemplary embodiment. In an alternative exemplary embodiment, fuel feed line 4 and feed pipe 5 can (initially) represent separate modules which are connected to one another (during assembly). For example, the feed pipe 5 and the fuel feed line 4 can be inserted (inserted) into one another at least in sections and connected in a sealing manner. The feed pipe 5 has an inlet 14 and an outlet 16 . The inlet 14 is provided with a connecting piece 18 and the outlet 16 of the feed pipe 5 opens centrally into the bottom area 6 of the evaporator holding body 2 . In the illustrated embodiment, the feed pipe 5 is welded to the evaporator holding body 2 .

The fuel feed line 4, in particular the fuel feed pipe 5, is provided with a nucleation device 20. 3 shows a first embodiment of a nucleation device 20. The fuel supply pipe 5 has an inner lateral surface 11 and an outer lateral surface 12. FIG. The inner lateral surface 11 has a nucleation surface 22 . In the representation shown here, the nucleation surface 22 extends in the circumferential direction over the entire surface of the inner lateral surface. Such a nucleation surface 22 has projections and/or depressions which serve as nucleation sites for the heterogeneous nucleation of gas bubbles, in particular from low-boiling components of the fuel. The nucleation surface 22 is in particular one as in 5 a to f rough or structured surface shown as an example. while showing 5a a surface that is provided with regular structures. This structure essentially has edged structures with points. In particular, it can be a knurled surface. 5b show a first corrugated surface with a first amplitude and wavelength. 5c shows another surface provided with regular structures, which in contrast to 5a has flattened tips. However, due to the flattening on the surface, the number of nucleation points of each structural unit increases. 5d shows a surface similar to the surface in 5b , but with a lower wavelength and amplitude.

5e and 5f show irregular surface structures, which 5e essentially with pips and in 5f are shown essentially with rounded structures.

4a shows a further embodiment of a fuel supply line. In this embodiment, a further element 24 in the form of a displacement wire 26 is arranged in the feed pipe 5 . Such a displacement wire extends over part or all of the supply pipe 5 and is fixed in place in it. This further element 24 is provided with a nucleation surface 22, which in particular has a surface as in 5 a through f is the rough or textured surface exemplified. The nucleation surface can be formed exclusively on the further element 24, or further nucleation surfaces 22, as in 3 shown. The nucleation surface 22 can be arranged on all surfaces of the displacement wire 26 that extend parallel to a longitudinal axis of the displacement wire, or only on part of it, in particular on one side or two sides.

4b shows a further embodiment of a fuel supply line. In this embodiment, the fuel feed line 4 comprises a first feed pipe 5a and a second feed pipe 5b. A component 32 is connected to the fuel feed line. The device has a cylindrical interior. An inner diameter is shown here smaller than that of the first and second lead pipes. However, this is optional and could also be the same or larger. On an interior surface of device 32 is a nucleation surface 22, as in the previously described embodiments. Alternatively or additionally, one or more bodies can be arranged in the component, which are preferably made of glass or ceramic and/or are present in the form of small plates, rods, sleeves, tubes, beads and/or stones.

6 shows schematically an embodiment of an evaporator receiving device. The evaporator receiving body 2 has a central opening on the bottom, which is covered by the evaporator element 3 . The feed pipe 5 of the fuel feed line 4 is in 6 welded directly to the bottom area 6 of the evaporator receiving body 2 at the outlet 16 of the feed pipe 5 .

7 shows an example of an embodiment in which a heat supply element 28 is arranged on an outer lateral surface 12 of the feed pipe 4 . The heat supply element 28 is designed in particular as a passive element or active heating element 30 . Alternatively, a heat supply element 28 can also be attached to the in 1 shown outer surface 19 of the connecting piece 18 can be arranged. In addition to the one-piece configuration of evaporator receiving body 2 and feed pipe 5 shown, the feed pipe 5 can also be connected to the evaporator receiving body 2 in a known manner. For this purpose, the evaporator receiving body 2 can in particular have a pipe connection piece with a connecting device.

8th shows a heating device 100 according to the invention with a heater assembly 1 with an evaporator burner. Reference number 50 designates a fuel source, in particular a metering pump connected to a fuel tank. The fuel supply line 4 is arranged between the fuel source 50 and the heating device. A connecting piece 18 is arranged at an inlet 14 of a feed pipe 5 . The connecting piece 18 is also connected to a flexible line 48 or to a rigid line. The emptying device 10 is arranged in the supply pipe 5 , which here, for example, comprises a component 32 which is connected into the supply pipe 5 . The component 32 can include the nucleation device 20, as also in 4b shown. If no component 32 is provided as a separate component, the nucleation device 20 can also be provided by nucleation surfaces 22 arranged in the supply pipe 5, such as in FIGS 3 or 4a shown, be provided. The emptying device 10 can also include a heat supply element 28 which is arranged in particular on the feed pipe 5 , for example also as an alternative to the component 32 .

At the outlet 16 of the feed pipe 5, the evaporator receiving body 2 connects. The evaporator holding body 2 has a base region 6 and a peripheral wall 8. In the evaporator holding body 2, an evaporator element 3 is arranged. Air supply openings 41 are arranged downstream in the peripheral wall 8 and are used to direct combustion air into the combustion chamber 9 . The combustion air can be conducted, for example, in an area around the feed pipe 5 into an antechamber 43 and then via a further chamber 44 to the air supply openings 41 and further into the combustion chamber 9 . Heat exchangers and an exhaust gas duct are not shown.

The proportions and pipe lengths shown are not limiting, but can be adapted to the actual lengths and proportions. In particular, the pipes can also have bends, which may be necessary when laying them in the vehicle, for example.

9 represents the course of the method according to the invention. In step a), a termination of a heating process is initiated. This can be done, for example, by a user input command or time-controlled.

In step b), the supply of fuel through the inlet 14 of the feed pipe 5 is terminated. For this purpose, in particular, an upstream metering pump can be switched off or an upstream shut-off valve can be closed. Thus, a flow rate of the fuel is reduced.

After step b), in step c) boiling bubbles are formed in the fuel, in particular on a nucleation surface 22, and at least part of the fuel in the fuel feed line is transferred into the combustion chamber 9 by means of the boiling bubbles. In this case, boiling bubbles are formed homogeneously by supplying heat, for example via the waste heat from the burner and possibly one or more heat supply elements 28 and/or heterogeneously on the rough or structured nucleation surface 22 . This heating of the fuel only occurs at the lower flow rate of fuel to carry. The formation of boiling bubbles leads to an increase in volume of the fuel in the fuel feed line 4, in particular the feed pipe 5, so that fuel is pressed through the outlet of the feed pipe 5, in particular into an evaporator element. In step d) the transferred part of the fuel is burned in the combustion chamber 9 of the heating device. The fuel supply line is thus at least partially emptied.

In 10 an exemplary embodiment of a fuel supply line 4 of a heating device 100 with a suck-back device 60 is shown. The heater is here connected to a fuel source.

The fuel supply line 4 runs from a fuel source 50 to a heater assembly 1 . The fuel supply line 4 is designed as a fuel supply for the heater assembly 1 running from the fuel source 50 to the heating assembly 1 in order to supply the heating device 100 with fuel B from the fuel source 50 .

In principle, the heater assembly 1 and the fuel feed line 4 are designed as described above in the exemplary embodiments.

The fuel source 50 includes a fuel tank 51 and a metering pump 52.

The fuel tank 51 is filled or can be filled with fuel B. This fuel B can be supplied from the fuel tank 51 with the metering pump 52 to the fuel supply line 4 in order to be conveyed to the heater assembly 1 via the fuel supply line 4 .

In this exemplary embodiment, the fuel feed line 4 has a first zone 4a and a second zone 4b. In the 10 until 14 a separation of the two zones 4a, 4b is illustrated by a thick dashed black line. In particular, the feed pipe with a nucleating device is located in zone 4b.

The fuel suck-back device 60, which has a fuel reservoir ΔV, is arranged in the first zone 4a of the fuel feed line.

Suck-back device 60 is designed to suck back fuel B from the second zone 4b, by means of a change in volume or an increase in volume of the fuel reservoir ΔV, into the first zone 4a - in particular at least for the most part into the fuel reservoir ΔV - in order to fill the second zone 4b in the Substantially completely empty (of fuel B).

In the embodiment according to 10 the fuel return device 60 or its fuel reservoir ΔV is formed by a cavity 61 and a piston 62 movably mounted therein.

For example, the cavity 61 and the plunger 62 form a device that essentially resembles the principle of a syringe.

The fuel B can be sucked out of the second zone 4b via a change in volume or an increase in volume of the fuel reservoir ΔV by moving the piston 62 in order to essentially completely empty the second zone 4b.

In order to move the piston 62 or to change the volume of the fuel reservoir ΔV, the fuel suck-back device 60 can have at least one (electric) actuator—for example a servomotor.

Alternatively or additionally, the fuel suck-back device 60 can have an (electrical) binary switching device--for example a magnetic switch--for moving the piston 62 or for changing the volume of the fuel reservoir ΔV.

The fuel B can be pushed out of the fuel reservoir ΔV back into the fuel feed line 4 and into the second zone 4b (towards the heater assembly 1) by means of an opposite volume change or reduction in volume of the fuel reservoir ΔV via a corresponding movement of the piston 62 .

The change in volume of the fuel reservoir ΔV can optionally be controlled, e.g. by means of a control device, in such a way that an oscillating system is avoided and it can be ensured that essentially all of the fuel is sucked out of (or introduced into) the second zone 4b in a controlled and defined manner and/or that no bubbles can form in fuel B when fuel B is sucked back or pushed out. For this purpose, according to the exemplary embodiment, the fuel B is pushed out and/or sucked back in a time window of at least 0.3 s, preferably at least 0.5 s, more preferably at least 1 s.

Depending on the fuel B used, an inner diameter of the fuel feed line 4 can vary. For example, an inner diameter of the fuel feed lines 4 can be between 0.5 mm and 4 mm, preferably from 1 mm to 4 mm, more preferably from 1 mm to 3 mm.

In the exemplary embodiment shown, a distance or line length between the suck-back device 60 and the heater assembly 1 is at most 1 m, preferably at most 0.8 m, more preferably at most 0.6 m Line volume than the first zone 4a.

Overall, in this exemplary embodiment, this results in a maximum change in volume of the fuel reservoir ΔV of the suck-back device 60 of at least 6 ml, preferably at least 8 ml, more preferably at least 10 ml.

In any case, the maximum change in volume of the fuel reservoir ΔV is dimensioned such that it holds at least the line volume of the second zone 4b.

In the exemplary embodiment shown, the fuel suck-back device 60 is connected to the fuel feed line 4 via a single T-connector, for example, in such a way that the fuel reservoir ΔV forms a partial volume of the fuel feed line 4 .

In an alternative exemplary embodiment, the fuel suck-back device 60 can be formed integrally on the fuel feed line 4 .

11 shows that previously in connection with 10 described embodiment of the fuel supply line 4 with a suction device 60 in a different state. In 2 a state of the fuel feed line 4 is shown in which all of the fuel B has been sucked out of the second zone 4b of the fuel feed line 4 back into the first zone 4a. The major part of the sucked-back fuel B is taken up in the fuel reservoir ΔV of the suck-back device 60 . A significant proportion of the sucked-back fuel B means at least 80%, preferably at least 90%, more preferably at least 95% of the line volume of the second section 4b.

By reducing the volume of the fuel reservoir ΔV, the fuel B can be pushed back into the second zone 4b of the fuel feed line 4 in order to start a heating process with the heater assembly 1 .

In an alternative embodiment, the fuel recirculation device 60 may be located near a connection to the fuel source 50, particularly near the metering pump 52. In this way, the second zone 4b of the fuel feed line 4 is formed by an entire line section between the heater assembly 1 and the metering pump 52 . In this way, an entire line section between the heater assembly 1 and the metering pump 52 can be emptied essentially completely by means of the fuel suck-back device 60 .

12 shows a further exemplary embodiment of a fuel supply line 4 with an alternative configuration of a suck-back device 60.

Instead of a suction device 60 with a cavity 61 and piston 62 movable therein, the fuel supply line 4 according to this exemplary embodiment has a suction device 60 which is formed by a (reversibly) deformable supply line section 63 in the fuel supply line 4 .

For the basic functionality and other features of the fuel supply line, reference is made explicitly to the previous 10 and 11 referenced embodiment described.

The deformable lead portion 63 has a shape memory device, such as a shape memory alloy, on a corresponding jacket portion of the fuel lead 4 . Alternatively, the corresponding casing section of the fuel feed line 4 (directly) can consist of or be formed from the shape memory device.

Alternatively or additionally, the deformable feed line section 63 has at least one piezoelectric switching device for changing the volume of the fuel reservoir.

In general, the deformable lead portion 63 is configured to change its shape (based on a received electrical signal) and thus its volume.

In particular, the deformable feed line section 63 can thus form or enlarge or reduce a fuel reservoir ΔV (serially in the fuel feed line 4).

In the embodiment according to 12 a possible enlargement of the deformable feed line section 63 or of the corresponding fuel reservoir ΔV is indicated with dashed lines.

A change in volume or an enlargement of the deformable feed line section 63 or its fuel reservoir ΔV can fuel B from the second zone 4b of the fuel feed line 4 into the first zone 4a (in particular the largest partially sucked back into the fuel reservoir ΔV).

In this way, the fuel supply line 4 can be designed with a suction device 60 as a single, unbranched fluid line.

In 13 is the fuel supply line 4 according to the embodiment 12 shown in a state with an enlarged fuel reservoir or enlarged deformable feed line section 63 .

In this way, all of the fuel B from the second zone 4b of the fuel feed line 4 is sucked back into the first zone 4a. The major part of the sucked-back fuel B is taken up in the fuel reservoir ΔV of the suck-back device 60 . A significant proportion of the sucked-back fuel B means at least 80%, preferably at least 90%, more preferably at least 95% of the line volume of the second section 4b.

By reducing the volume of the fuel reservoir ΔV, the fuel B can be pushed back into the second zone 4b of the fuel feed line 4 in order to start a heating process with the heater assembly 1 .

In 14 an embodiment of a heating device with a heater assembly 1 and a fuel supply line 4 is shown, which are arranged in a system.

The system can be part of a (motor) vehicle, for example.

The heater as well as the system has a high temperature area HT and a low temperature area NT. The high-temperature area HT is characterized in that those devices or devices that produce waste heat are arranged in this high-temperature area. In particular, such that a temperature in the high-temperature range HT is above a boiling point of the fuel B used. For example, the heater assembly 1 is arranged in the high-temperature area HT. In addition, the high-temperature area HT can have further heat-radiating devices 70, 80, such as a vehicle engine.

The low-temperature range NT is characterized in that a temperature predominantly prevailing therein is below a boiling point in the boiling range of the fuel B used.

The second zone 4b of the fuel supply line is thus long enough for a boiling point or boiling range of the fuel B used to be able to be reached at least temporarily during operation of the heater assembly 1 . The first zone 4a is at such a distance from the heater assembly 1 and possibly other heat sources that a temperature predominantly prevailing therein is below a boiling point or boiling range of the fuel B used. The fuel feed line 4 includes a suction device 60 in the first zone 4a.

Suck-back device 60 is designed to suck back fuel B from the second zone 4b, by means of a change in volume or an increase in volume of the fuel reservoir ΔV, into the first zone 4a - in particular at least for the most part into the fuel reservoir ΔV - in order to fill the second zone 4b in the Substantially completely empty (of fuel B).

In this way, the suck-back device 60 can suck the fuel B back from a high-temperature area HT into a low-temperature area NT.

This makes it possible to prevent fuel 4 remaining in the fuel supply line 4 from evaporating (for example after a heating process has ended).

Although in 15 the fuel source 50 is arranged in the low-temperature area NT, it can alternatively also be outside of the low-temperature area NT. What is (only) decisive is the arrangement of the suck-back device 60 in the/a low-temperature area NT.

At this point it should be pointed out that all the parts described above, viewed individually and in any combination, in particular the details shown in the drawings, are claimed to be essential to the invention.

Reference List

1

heater assembly

2

evaporator receiver body

3

evaporator element

4

fuel supply line

5

supply pipe

6

floor area

8th

peripheral wall

9

combustion chamber

10

emptying device

11

inner surface

12

outer surface

14

Entry

16

Exit

18

connecting piece

19

Outer surface of the connecting piece

20

nucleation facility

22

nucleation surface

24

another item

26

displacement wire

28

heat supply element

30

heating element

32

component

40

fastener

41

air supply opening

42

recess

43

antechamber

44

another chamber

B

fuel

50

fuel source

51

fuel tank

52

dosing pump

60

suction device

ΔV

fuel reservoir

61

cavity

62

Pistons

63

deformable lead section

70.80

heat radiating device(s)

100

heating device

HT

high temperature area

N.T

low temperature range

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102018111636 A1 [0002]
• DE 102018104517 [0003]
• DE 102004041202 C5 [0004]
• DE 102014103815 A1 [0005]
• DE 8403269 U1 [0006]

Claims (16)

Mobile heating device (100), in particular mobile vehicle heating device, comprising - a heater assembly (1) with a combustion chamber (9) and - a fuel supply line (4) for supplying liquid fuel to the heater assembly (1), wherein the heater assembly (1) comprises, in particular, an evaporator receptacle arrangement for evaporating liquid fuel, comprising an evaporator receptacle body (2) for accommodating an evaporator element (2) for distributing and evaporating liquid fuel, wherein the fuel feed line (4) comprises a feed pipe (5) with an inlet (14) for inputting fuel and an outlet (16) for discharging fuel to the combustion chamber (9), the fuel feed line (4) also having an emptying device (10) for partially or completely emptying the fuel feed line (4) through the outlet (16). heater (100) after claim 1 , wherein the emptying device (10) comprises a nucleation device (20) which comprises at least one rough and/or structured nucleation surface (22) for the formation of boiling bubbles. heater (100) after claim 2 , wherein the nucleation surface (22) is arranged on an inner lateral surface (11) of the feed pipe (5) and/or on an inner surface of a connecting piece (18) arranged at the inlet (14) of the feed pipe (5) and/or in an in the component (32) connected to the fuel feed line (4) is arranged, with the nucleation surface (22) extending in particular over the entire inner lateral surface (11) of the feed pipe (5). heater (100) after claim 2 or 3 A further element (24) having the nucleation surface (22) is arranged in the fuel feed line (4), in particular in the feed pipe (5), the further element (24) being designed in particular as a displacement wire (26). Heating device (100) according to one of claims 2 until 4 , wherein the nucleation surface (22) has been produced by means of mechanical deformation and/or by applying a coating and/or by means of milling and/or by means of an etching process. heater (100) after claim 3 , wherein the feed pipe (5) comprises a first feed pipe (5a) and a second feed pipe (5b) and the component (32) is arranged between the first feed pipe (5a) and the second feed pipe (5b) and/or wherein the component has a or a plurality of bodies arranged therein, in particular bodies made of glass or ceramics, one surface of the body or bodies being part of the nucleation surface (22). Heating device (100) according to one of the preceding claims, wherein the emptying device (10) comprises a heat supply element (28) which is attached to an outer lateral surface (12) of the feed pipe (5) and/or to an outer surface (19) of one at the inlet (14 ) of the supply pipe (5) arranged connecting piece (18) is arranged. heater (100) after claim 7 , wherein the heat supply element (28) comprises an active heating element. heater (100) after claim 7 or 8th , wherein the heat supply element comprises a passive thermally conductive element which conducts heat from a heat source to the outer lateral surface (12) or outer surface (19), wherein the passive thermally conductive element, in particular a hose clamp, comprises. Heating device (100) according to one of the preceding claims, wherein the fuel supply line (4) is designed to run as a fuel supply for the heating device (100) from a fuel source (50) to the heating device (100) and has a first (4a) and a second zone (4b ), wherein the fuel supply line (4) in the first zone (4a) has a suction device (60) which includes a fuel reservoir (ΔV), wherein the suction device (60) is designed to, by means of a change in volume of the fuel reservoir (ΔV), To suck fuel (B) from the second zone (4b), in particular completely, back into the first zone (4a). heater (100) after claim 10 , wherein the fuel reservoir (ΔV) is formed by at least one cavity (61) and at least one movable piston (62), such that the fuel (B) sucked back from the second zone (4b) can be at least partially accommodated in the fuel reservoir (ΔV). or wherein the fuel reservoir (ΔV) is formed by at least one deformable feed line section (63), which is preferably arranged in series in the fuel feed line (4), such that the fuel (B) sucked back from the second zone (4b) is at least partially can be accommodated in the fuel reservoir (ΔV). Heating device (100) according to one of claims 9 or 10 , wherein the Rücksaugvorrich device (60) comprises or is connected to a controller. Heating device (100) according to one of the preceding claims, wherein the fuel supply line (4) is welded to the evaporator receiving body (2). Method for operating a mobile heating device (100), in particular for a heating device with an evaporator burner, in particular a heating device according to one of the preceding claims, in which a complete or partial emptying of a fuel supply line (4) of the heating device (100) takes place, the heating device ( 100) a feed pipe (5) having an inlet (14) for inputting fuel and an outlet (16) for discharging fuel to a combustion chamber (9), the method comprising the following steps: a) initiating the termination of a heating process, b) ending a fuel feed through the inlet (14) of the feed pipe (5), c) After step b), formation of boiling bubbles in the fuel, in particular on a nucleation surface (22), and transferring at least part of the fuel in the fuel feed line (4) into the combustion chamber (9) by means of the boiling bubbles, d) burning off the transferred part of the fuel in the combustion chamber (9). procedure after Claim 14 , further comprising: sucking back fuel (B) remaining in a second zone (4b) of the fuel feed line (4) into a first zone (4a) of the fuel feed line (4), by a change in volume of a fuel reservoir (ΔV) in the first zone (4a) of the fuel supply line (4) is arranged. procedure after claim 15 , wherein the method after sucking back comprises the steps of: e) initiating a further heating process with the heating device (100); f) ejecting the fuel (B) from the fuel reservoir (ΔV) into the fuel feed line (4); g) ejecting at least part of the fuel (B) that has been ejected, in particular all of the fuel (B) that has been ejected.

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