DE102021112549A1 - PORTABLE HEATING DEVICE WITH A FUEL LINE AND METHOD OF OPERATING A PORTABLE HEATING DEVICE - Google Patents

Abstract

The present invention relates to a mobile heating device, in particular a vehicle heating device, comprising a heater assembly with a combustion chamber and a fuel supply line for supplying liquid fuel to the heater assembly, the heater assembly in particular having an evaporator receptacle arrangement for evaporating liquid fuel, comprising an evaporator receptacle body for accommodating an evaporator element for distributing and evaporating liquid fuel, wherein the fuel supply line has a first and a second zone, wherein the fuel supply line has a suction device in the first zone, which includes a fuel reservoir (ΔV), wherein the suction device is designed to do so by means of a change in volume of the fuel reservoir (ΔV) to suck fuel from the second zone, in particular completely, back into the first zone.

Description

The invention relates to a mobile heating device, preferably a vehicle heating device, and a method for operating a mobile heating device.

Fuel-operated heating devices and corresponding fuel supply lines to the corresponding heating device are known. Such heating devices and fuel supply lines can be used in (motor) vehicles, in particular in fuel-powered or electrically powered vehicles, for example as auxiliary and/or auxiliary heating. For example, in evaporator burners, liquid fuel is introduced into an evaporator via a fuel feed 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 fundamental problem with (vehicle) heating devices and corresponding fuel supply lines of the above-mentioned type is that, for example after the end of a heating process, the fuel supply line is in an undefined (filling) state. The degree of the (filling) state or line emptying of the fuel supply line after the end of a heating process is difficult or impossible to predict, since it is to a certain extent random or arbitrary and in particular also dependent on the (installation) positions of the fuel supply line or the Heating device or a tank or a corresponding vehicle varies.

In the DE 10 2008 057 636 A1 a fluid supply system for a vehicle heater is described that is intended to optimize delivery conditions of fuel in a feed line to the heater. However, this system is perceived as comparatively complex, since many different fluid lines are coupled and some of these have to be networked by means of a switching valve to form a branched line system. Under certain circumstances, this can lead to undesired side effects such as the formation of bubbles in the fuel of the fluid system. Furthermore, due to the complexity, the system is comparatively expensive and complex to implement. In addition, it is also disclosed here that, in order to avoid gumming up of the fuel pump or the switching valve in the event of a longer standstill, the fuel pump can be operated briefly after predetermined time intervals, so that at least the first fluid line up to the switching valve and a part of the second fluid line ( line to the heater) is filled with fuel. Therefore, the above-mentioned disadvantages of the (filling) states of a supply line to a heating device that is at least partially filled with fuel, which are difficult or impossible to predict, also arise here.

These (filling) states of a fuel supply line, which are difficult or impossible to predict, are therefore problematic, since daily or location-dependent temperature fluctuations or vehicle-specific and/or system-specific waste heat can result in fuel remaining (or present) in the fuel supply line being released through the heating device into the environment escape, in particular evaporate, can.

On the one hand, this is disadvantageous from an ecological point of view and, on the other hand, it is also undesirable from the point of view of consumers and/or manufacturers, since in this way fuel consumption is unnecessarily increased. In addition, the undefined states in a fuel supply line result in non-optimal conditions for starting up a heating device.

It is therefore the object of the present invention to provide an improved mobile heating device comprising the fuel feed line and an improved method for operating a mobile heating device. In particular, undefined (filling) states of the fuel supply line should be avoided during or after operation and a rest 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 17 with regard to the method. Appropriate configurations result from the respective dependent claims.

In particular, the object is achieved by a mobile heating device, in particular a vehicle heating device, which comprises a heater assembly with a combustion chamber and a fuel supply line for supplying liquid fuel to the heater assembly, the fuel supply line having a first and a second zone, the fuel supply line being in the first Zone has a sucking-back device, which comprises a fuel reservoir, wherein the sucking-back device is 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. The fuel supply line is designed for connection to a fuel source.

An essential idea of the invention is to provide a simple (if possible unbranched) and cost-effective heating device with a fuel supply line that can be emptied in a controlled manner (after a heating process of the heating device has ended) without fuel residues remaining in the fuel supply line. This prevents fuel from evaporating from the fuel supply line via the heating device (into an area surrounding the heating device) (evaporative emission). According to the invention, an ambient temperature in the vicinity of the fuel feed line is taken into account in particular, since said vaporization of the fuel could occur specifically in areas where an ambient temperature is close to or above a boiling point of the fuel. In order to avoid this, the fuel is sucked back into a (first) zone with a lower temperature (below a boiling point of the fuel) in a controlled manner according to the invention. This takes place via corresponding line lengths of the fuel supply line and a corresponding arrangement of the suck-back device in such a (first) zone. For example, when using the fuel line and a corresponding heater in a vehicle, the high temperatures near or above a boiling point of the fuel can be caused by a proximity (of the fuel in the fuel line) to a vehicle engine or to the heater itself, by the respective heat radiation at or after Plant, surrendered (second zone). Alternatively, such a (second) zone can also be a zone that heats up comparatively strongly as a result of solar radiation. A (first) zone with a lower temperature (below a boiling point of the fuel) in which the suck-back device is arranged can be, for example, a vehicle underbody area. Fuel that is temporarily stored in a suck-back device arranged in this way or in a corresponding fuel reservoir (for example until the next heating process) cannot evaporate through the heating device. For the purposes of this invention, a boiling point of the fuel denotes the specific boiling point in the case of fuels composed of only one component and, in the case of fuels composed of several components, the start of boiling or minimum temperature of the boiling range.

In one embodiment, the fuel reservoir is formed by at least one cavity and at least one movable piston, such that the fuel sucked back from the second zone can be at least partially accommodated in the fuel reservoir.

Such a suck-back device, which is formed by (at least) one cavity and (at least) one corresponding plunger (for example similar to a syringe), can be used comparatively easily and inexpensively. In addition, it has surprisingly been shown that such a comparatively simply constructed suck-back device works particularly effectively (with regard to the fuel suck-back). In this way it can be ensured that the fuel in the second zone of the fuel line can be emptied completely and in a defined (controllable and predictable and reproducible) manner and thus an evaporative emission of fuel from the heating device can be reduced to a minimum.

In one embodiment, the suck-back device has at least one actuator, in particular at least one servomotor and/or a binary switching device, for changing the volume of the fuel reservoir.

This makes it possible for the fuel reservoir to be able to be controlled, for example, via a control unit (for example of a vehicle or the heating device). As a result, the second zone of the fuel supply line can be checked after a heating process and emptied in a defined state. Thus, the evaporative emission of fuel from the heater is reduced to a minimum. At the same time, the controllable fuel reservoir at the start of a heating process by pushing the fuel out of the fuel reservoir into the fuel supply line makes it possible for fuel to be available comparatively quickly in the heating device, for example in a corresponding evaporator. In this way, a quick, controlled and defined start-up of the heating device is also made possible.

In an alternative embodiment, 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 way, the fuel supply line can be designed to be completely unbranched. Branches, for example through several T-connectors, always represent areas in a fluid line or in a fuel line that are prone to failure. For example, bubbles increasingly form in these branch areas, which can have a negative effect on efficient operation of the heating device. By designing the fuel supply line with a serial fuel reservoir, the risk of disruptions within the line is reduced for example through the formation of bubbles, reduced to a minimum.

In one embodiment, the deformable feed line section comprises a shape memory device and/or a piezoelectric switching device.

A serial or in-line fuel reservoir can be implemented (directly) in the fuel supply line with a shape memory device, such as a shape memory alloy, and/or a piezoelectric switching device within the fuel supply line. On the one hand, as a result, branches in the fuel supply line are avoided (as described above), on the other hand, a fuel reservoir design is particularly space-saving and low-maintenance.

In one embodiment, the suck-back device comprises at least one control device or is connected to a control device. In particular, a suck-back speed can be adjusted and/or a suck-back speed profile can be set by means of the control device. In particular, a suck-back speed at the beginning of the suck-back and/or at the end of the suck-back can be reduced, e.g. by a deformation of the deformable section or a stroke speed of a piston being adjusted accordingly. Alternatively, a correspondingly slow speed can also be selected for the suck-back process. In an analogous manner, the fuel reservoir can also be emptied again.

As a result, an oscillating system is avoided or at least dampened and it can be ensured that essentially all of the fuel is sucked out of the second zone in a controlled and defined manner. In this way, evaporative fuel emission from the heater is reduced to a minimum.

In one embodiment, the fuel feed line has an inner diameter of 0.5 mm to 4 mm, preferably 1 mm to 4 mm, more preferably 1 mm to 3 mm.

The inner diameter of the fuel feed line can vary depending on the type of fuel, for example. For example, an inner diameter of 1 mm to 3 mm is commonly used for petrol and a comparatively larger inner diameter for diesel than for petrol. A flow rate of the fuel (when the heating device is in operation) can be increased and the formation of vapor bubbles can be avoided by means of an overall comparatively small inner diameter of the fuel feed line. Under certain circumstances, the inside diameter of the fuel feed line can be additionally reduced further by introducing a displacement wire into the fuel feed line or by introducing it in sections.

In one embodiment, the length of the fuel supply line between the suction device, in particular the fuel reservoir of the suction device, and the heating device is at most 1 m, preferably at most 0.8 m, more preferably at most 0.6 m.

In this way, a line volume to be emptied can be kept comparatively small. This enables the line or the second zone to be emptied easily and in a controlled manner with little expenditure of energy.

In one embodiment, the second zone of the fuel feed line has a smaller line volume than the first zone of the fuel feed line.

Due to the fact that the length of the fuel supply line between the suction device and the heating device is kept comparatively small or short (compared to a total length of the fuel supply line of typically at least 2 m), (only) a relatively small amount of fuel has to be sucked back in order to to empty the second zone of the fuel supply line. As a result, the suck-back device can be operated in an energy-saving manner, so that overall efficient operation of the fuel suck-back is made possible.

In one embodiment, a maximum change in volume of the fuel reservoir of the suck-back device is at least 6 ml, preferably at least 8 ml, more preferably at least 10 ml.

A maximum change in volume of the fuel reservoir is to be understood as meaning a fuel or fluid volume that the suck-back device can take up or suck back as a maximum (without taking into account any dead volume that may be present due to the design). Such a dimensioned maximum change in volume of the fuel reservoir makes it possible to completely or almost completely empty the second zone of the fuel supply line by sucking or absorbing the remaining fuel in the second zone into the fuel reservoir. This reduces evaporative emissions from the fuel to a minimum.

In one embodiment, the fuel supply line is designed as a substantially unbranched line, preferably comprising at most one T-connector.

An unbranched line is to be understood here as meaning that the line has no further fluid-transporting branches or arms (branches) or merely consists of a (single) continuous line arm. In particular such that the fuel supply line (precisely) has a (fuel) input (source side) and (precisely) a (fuel) output (heating device side) and preferably has no further inflows or outflows from or into the fuel supply line. In particular, the fuel reservoir is designed as a (partial) volume of the fuel supply line. However, the fuel supply line can be designed to be quite flexible and, for example, run in a curved or meandering manner at least in sections. The unbranched design of the fuel supply line enables operation that is particularly not susceptible to faults, in particular with little formation of vapor bubbles in the fuel. Likewise, the unbranched or almost (at most a single T-connector) unbranched design of the fuel supply line results in a particularly simple and uncomplicated fluid control system, so that the fuel can always be sucked back under well-defined conditions, so that evaporative emissions can be reduced to a minimum. At the same time, the fuel supply line can be implemented in a particularly cost-effective and low-maintenance manner in this simple manner.

In one embodiment, the fuel supply line comprises a supply tube having an inlet for inputting fuel and an outlet for discharging to a combustion chamber of the heating device, the fuel supply line further having a drain device for partially or completely draining the fuel supply line through the outlet.

The fuel supply line can be additionally 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 either a straight pipe or a bent pipe or pipe provided with bends. 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.

In one embodiment, the emptying device comprises a nucleation device which comprises at least one rough and/or structured nucleation surface for the formation of boiling bubbles.

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

In one configuration, the heating device comprises a high-temperature area and a low-temperature area, with the heating assembly and optionally a heat supply element and a second zone of the fuel feed line being arranged within the high-temperature area, with the first zone of the fuel feed line being arranged in the low-temperature area.

This results in the same advantages as have already been described in connection with the fuel supply line. An essential idea of the system is that the fuel can be sucked back into the first zone or correspondingly behind an (imagined) thermal boundary between the high-temperature area and the low-temperature area in order to prevent the remaining fuel from evaporating.

In one embodiment, the high-temperature region essentially has a temperature above a boiling point of the fuel and/or the low-temperature region has a temperature below the boiling point of the fuel, in the case of a multi-component fuel below a minimum temperature of the boiling range.

In this way, the fuel can be sucked back into the first zone and is thus (only) exposed to a temperature below its boiling point or boiling range. For example, in this way the fuel is physically far (enough) from the heater assembly (which will of course have some residual heat after heating) or other heat radiating devices (such as a vehicle engine). This effectively prevents fuel from evaporating in the fuel feed line after a heating process has ended.

1. a) Beenden eines Heizvorgangs mit der Heizvorrichtung und/oder Beenden einer Brennstoffzufuhr von der Brennstoffquelle zu der Heizvorrichtung;
2. b) 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.

The object according to the invention is also achieved by a method for operating a mobile heating device, in particular a vehicle heating device, the method comprising the following steps:

1. a) ending a heating process with the heating device and/or ending a fuel supply from the fuel source to the heating device;
2. b) fuel remaining in a second zone of the fuel feed line is sucked back into a first zone of the fuel feed line by a change in volume of a fuel reservoir arranged in the first zone of the fuel feed line.

This results in the same advantages as have already been described in connection with the heating device.

Features of the heating device can be transferred to the method according to the invention. Features of the method according to the invention can also be transferred to the heating device according to the invention by configuring the corresponding device in such a way that it is suitable for carrying out the corresponding method features.

Step b) can begin at the same time as step a), or during step a), or after step a) has ended.

• c) Einleiten eines Heizvorgangs mit der Heizvorrichtung;
• d) Ausschieben des Brennstoffs aus dem Brennstoffreservoir in die Brennstoffzuleitung;
• e) Abbrennen zumindest eines Teils des ausgeschobenen Brennstoffes, insbesondere des ganzen ausgeschobenen Brennstoffes.

In one embodiment, the method after step b) comprises the following steps:

• c) initiating a heating process with the heating device;
• d) ejecting the fuel from the fuel reservoir into the fuel feed line;
• e) Burning off at least part of the ejected fuel, in particular all of the ejected fuel.

In one embodiment, the change in volume of the fuel reservoir for pushing out and/or sucking back the fuel takes place in a damped manner in a time window of at least 0.3 s, preferably at least 0.5 s, more preferably at least 1 s.

The fuel can be sucked back in a controlled manner by appropriately controlling the sucking-back device. This avoids an oscillating system and it can be ensured that essentially all of the fuel is sucked out of the second zone in a controlled and defined manner. In this way, evaporative fuel emission from the heater is reduced to a minimum.

• f) Bildung von Siedeblasen im Brennstoff, insbesondere an einer Nukleationsoberfläche, und Überführen zumindest eines Teils des in der Brennstoffzuleitung befindlichen Brennstoffes mittels der Siedeblasen in eine Brennkammer der Heizvorrichtung,
• g) Abbrennen des überführten Teils des Brennstoffes in der Brennkammer .

In one embodiment, the method after step a) comprises the following steps:

• f) formation of boiling bubbles in the fuel, in particular on a nucleation surface, and transferring at least part of the fuel in the fuel feed line into a combustion chamber of the heating device by means of the boiling bubbles,
• g) burning off the transferred part of the fuel in the combustion chamber.

The invention is also described below with regard to further details, features and advantages, which are explained in more detail with reference to the figures. The features and feature combinations described below, as shown below in the figures of the drawing and described with reference to the drawing, can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the invention.

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

This shows:

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

In 1 an exemplary embodiment of a heating device 100 with a fuel feed line 4 with a suction device 60 is shown. The heating device 100 comprises a heater assembly 1 and a fuel supply line 4. The fuel supply line 4 is connected to a fuel source 50 here.

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 heater assembly 1 in order to supply the heating device 100 with fuel B from the fuel source 50.

In principle, the heating device 100 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 fed from the fuel tank 51 with the metering pump 52 to the fuel feed line 4 in order to be conveyed via the fuel feed line 4 to the heating device 1 .

In this exemplary embodiment, the fuel feed line 4 has a first zone 4a and a second zone 4b. In the 1 until 5 a separation of the two zones 4a, 4b is illustrated by a thick dashed black line.

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 1 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.

Via a change in volume or an increase in volume of the fuel reservoir ΔV by moving the piston 62, the fuel B can be sucked out of the second zone 4b 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.

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 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 heating device 1).

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 3 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 heating device 1 is at most 1 m, preferably at most 0.8 m, more preferably at most 0.6 m. In addition, the second zone 4b of the fuel feed line 4 preferably has a smaller 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 .

2 shows that previously in connection with 1 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 heating device 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 heating device 1 and the metering pump 52 . In this way, an entire line section between heating device 1 and metering pump 52 can be emptied essentially completely by means of fuel return device 60 .

3 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 1 and 2 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 3 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 increase in the deformable feed line section 63 or its fuel reservoir ΔV allows fuel B to be sucked back from the second zone 4b of the fuel feed line 4 into the first zone 4a (in particular largely 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 4 is the fuel supply line 4 according to the embodiment 3 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 heating device 1 .

In 5 an exemplary embodiment of a heating device 100 with a heater assembly 1 and a fuel feed 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. In one embodiment, a heat-radiating device 70, 80 can be connected to the fuel supply line 4 via a heat supply element 28.

The low-temperature range NT is characterized in that a temperature predominantly prevailing therein is below a boiling point or 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 5 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.

The heating device 100 and a connection between the fuel supply line 4 and the heater assembly 1 are described in more detail below.

6 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 7 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. 8th 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 . 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 10 a) to f) rough or structured surface shown as an example.

9 shows an alternative 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 10 a) to f) is the rough or structured surface shown as an example. 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.

In an embodiment that is not shown, 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 leads pipe. However, this is optional and could also be the same or larger. On an inner surface of the 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.

11 shows schematically an embodiment of an evaporator receiving device. The evaporator receiving body 2 has a central opening on the bottom, which is overlaid by the evaporator element 3 . The feed pipe 5 of the fuel feed line 4 is in 11 welded directly to the bottom area 6 of the evaporator receiving body 2 at the outlet 16 of the feed pipe 5 .

12 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 6 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.

13 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 . The emptying device 10 is arranged in the supply pipe 5 , which here, for example, comprises a component 32 connected into the supply pipe 5 . The component 32 can comprise the nucleation device 20 . 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 8th or 9 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.

14 represents the course of the method according to the invention, the sequential order representing the beginning of the respective steps (a), b), c), ...) In step a), a heating process is ended and/or a fuel supply from the fuel source 50 of the heater ended. This can be done, for example, by a user input command or time-controlled.

In step b), residual/remaining fuel is sucked back from a second zone 4b of the fuel feed line 4 into a first zone 4a of the fuel feed line 4 by a volume change of a fuel reservoir ΔV arranged in the first zone 4a of the fuel feed line 4. For this purpose, a return suction device 60 is controlled accordingly. Step b) can be carried out at least partially overlapping with step a).

Optionally, a heating process with the heating device 100 can be initiated again in a subsequent step c). For example (again) by a corresponding user input command or time-controlled.

In a step d), the fuel B can then be ejected from the fuel reservoir ΔV back into the fuel feed line 4, so that in a step e) at least part of the ejected fuel (B) can be burned off.

A corresponding change in volume of the fuel reservoir ΔV for pushing out and/o The sucking back of the fuel B preferably takes place in a damped manner in a time window of at least 0.3 s, preferably at least 0.5 s, more preferably at least 1 s.

Alternatively or additionally, steps f) and g) can be carried out after step a) (in 14 not shown).

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.

In step f), boiling bubbles are formed in the fuel B, 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, e.g. 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 comes into play at the lower flow rate of the fuel. 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 g) 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.

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

4a

first zone

4b

second zone

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 device

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 102008057636 A1 [0004]

Claims (20)

Mobile heating device (100), in particular 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 receiving arrangement for evaporating liquid fuel, comprising an evaporator receiving body (2) for receiving an evaporator element (2) for distribution and evaporation liquid fuel, wherein the fuel feed line (4) has a first (4a) and a second zone (4b), wherein the fuel feed line (4) in the first zone (4a) has a suction device (60) which has a fuel reservoir (ΔV) comprises, wherein the suck-back device (60) is designed to suck fuel (B) from the second zone (4b), in particular completely, back into the first zone (4a) by means of a volume change in the fuel reservoir (ΔV). heater (100) after claim 1 , 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). is. heater (100) after claim 2 , wherein the suck-back device (60) has at least one actuator, in particular at least one servomotor and/or a binary switching device, for changing the volume of the fuel reservoir (ΔV). heater (100) after claim 1 , 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 in the fuel reservoir (ΔV) can be accommodated. heater (100) after claim 4 , wherein the deformable feed line section (63) comprises a shape memory device and/or a piezoelectric switching device. Heating device (100) according to any one of the preceding claims, wherein the suck-back device (60) comprises a controller or is connected to a controller. Heating device (100) according to one of the preceding claims, wherein the fuel supply line (4) has an inner diameter of 0.5 mm to 4 mm, preferably 1 mm to 4 mm, more preferably 1 mm to 3 mm. Heating device (100) according to one of the preceding claims, wherein a line length of the fuel supply line (4) between the suction device (60), in particular the fuel reservoir (ΔV) of the suction device (60), and the heater assembly (1), at most 1 m, preferably at most 0.8 m, more preferably at most 0.6 m. Heating device (100) according to one of the preceding claims, wherein the second zone (4b) of the fuel feed line (4) has a smaller line volume than the first zone (4a) of the fuel feed line (4). Heating device (100) according to one of the preceding claims, wherein a maximum change in volume of the fuel reservoir (ΔV) of the suck-back device (60) is at least 6 ml, preferably at least 8 ml, more preferably at least 10 ml. Heating device (100) according to one of the preceding claims, wherein the fuel supply line (4) is designed as a substantially unbranched line, preferably comprising at most one T-connector. Heating device (100) according to any one of the preceding claims, comprising a supply pipe (5) having an inlet (14) for inputting fuel and an output (16) for discharging to a combustion chamber (9) of the heating device (100), the fuel supply line ( 4) furthermore has an emptying device (10) for partially or completely emptying the fuel supply line (4) through the outlet (16). heater (100) after claim 12 , 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 13 , wherein the emptying device (10) comprises a heat supply element (28) which is arranged on an outer lateral surface (12) of the feed pipe (5) and/or on an outer surface (19) of a connecting piece ( 18) is arranged. Heating device (100) according to one of the preceding claims, comprising a high-temperature area (HT) and a low-temperature area (NT), the heater assembly (1) having a second zone (4b) of the fuel feed line and optionally a heat supply element (28) are arranged within the high-temperature area (HT), the first zone (4a) of the fuel feed line (4) being arranged in the low-temperature area (NT). heater (100) after claim 15 , wherein the high-temperature region (HT) essentially has a temperature above a boiling point or above a minimum temperature of a boiling range of the fuel (B) and/or wherein the low-temperature region (LT) has a temperature below the boiling point or below a boiling range of the fuel (B). . Method for operating a mobile heating device, in particular for a heating device with an evaporator burner, in particular 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), comprising the following steps: a) ending a heating process with the heating device (100) and/or ending a fuel supply from a fuel source (50) to the heating device (100); b) Fuel (B) remaining in a second zone (4b) of the fuel feed line (4) is sucked back into a first zone (4a) of the fuel feed line (4) by a change in volume of a fuel reservoir (ΔV) located in the first zone (4a ) of the fuel supply line (4) is arranged. procedure after Claim 17 , wherein the method according to step b) comprises the following steps: c) initiating a heating process with the heating device (100); d) pushing out the fuel (B) from the fuel reservoir (ΔV) into the fuel feed line (4); e) Burning off at least part of the fuel (B) that has been pushed out, in particular all of the fuel (B) that has been pushed out. procedure after Claim 17 or 18 , the change in volume of the fuel reservoir (ΔV) for pushing out and/or sucking back the fuel (B) in a time window of at least 0.3 s, preferably at least 0.5 s, more preferably at least 1 s. Procedure according to one of claims 17 until 19 , wherein the method after step a) comprises the following steps: f) formation of boiling bubbles in the fuel, in particular on a nucleation surface (22), and transferring at least part of the fuel located in the fuel feed line into a combustion chamber (9) of the heating device by means of the boiling bubbles (100), g) burning off the transferred part of the fuel in the combustion chamber (9)

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