Lifting Piston Fuel Pump and Method for Starting and Operating a Motor Vehicle Heating System

Abstract

The invention relates to a reciprocating piston fuel pump (16), in particular for an automotive heater (10) which is driven electromagnetically and is provided for delivering liquid fuel, having a damping element (34) comprising an elastomer (36) for damping pulsations created by the reciprocating piston fuel pump (16). According to this invention, means (22, 46, 48, 50) for heating the elastomer (36) are provided. The invention also relates to a method for starting and operating an automotive heater (10) that is operated with liquid fuel and has a burner (14) and a reciprocating piston fuel pump (16) with a damping element (34) comprising an elastomer (36) for damping pulsations created by the reciprocating piston fuel pump (16). According to this invention, the elastomer (36) is already heated before ignition of the burner (14).

Description

The present invention relates to a reciprocating piston fuel pump, in particular for an automotive heater that is electromagnetically driven and is provided for pumping liquid fuel, having a damping element comprising an elastomer for damping pulsations generated by the reciprocating piston fuel pump.

The present invention also relates to a method for starting and operating an automotive heater operated with liquid fuel, having a burner and a reciprocating piston fuel pump having a damping element comprising an elastomer for damping pulsations generated by the reciprocating piston fuel pump.

A generic reciprocating piston fuel pump is disclosed, for example, in the publication Fahrzeug- und Verkehrstechnik, Technische Mitteilungen [Automotive and Traffic Engineering, Technical Reports] 97 (2004), No. 1, pp. 9-11 and shown as a schematic sectional view in FIG. 1.

The reciprocating piston fuel pump 16′ shown in FIG. 1 is provided for pumping liquid fuel in the direction represented by the arrows, namely from the fuel inlet 18 to a fuel outlet 20. As soon as a suitable voltage is applied to an electric terminal 42, electricity flows through a winding 22, thus electromagnetically inducing a movement of a reciprocating piston 24. First, fuel in a pump chamber 30 is ejected through a nonreturn valve 28 against the hydraulic resistance of the output line. Then the electric current passing through the winding 22 is terminated. A restoring spring 26 presses the reciprocating piston 24 toward the left into its resting position. Liquid fuel is drawn in through an intake valve 32, filling the pump chamber 30. With this pump principle, it is also possible to achieve conveyance of fuels that is very precise volumetrically, even those fuels having a very low viscosity. The delivery quantity can be controlled exactly through the frequency of the triggering voltage pulses.

However, unwanted pulsations occur in the fuel system due to the back-and-forth movement of the reciprocating piston 24. It is already known that to at least partially suppress these pulsations, a damping element 34 may be provided, comprising a bellows-like elastomer 36. When liquid fuel passes through a borehole 40 and comes in contact with the elastomer 36, the elastomer 36 expands into a neighboring 38, which is provided in a damper housing formed by a molded plastic part 44. The prerequisite for this is a certain backpressure in the fuel system which ensures that the elastomer 36 will be “secured” in place.

One problem with the reciprocating piston fuel pump 16′ shown in FIG. 1 is that the damping element 34 has little or no function in extreme ambient cold, e.g., at a temperature below −23° C., because the elastomer 36 hardens or undergoes a glass transition (a typical elastomer point [sic; glass transition point] of the elastomer 36 is −23° C., for example). Another problem is that so-called Arctic¹ diesel, which is the only fuel approved for use at temperatures below −20° C. for diesel burners, produces a much lower backpressure at temperatures below −20° C. than does winter diesel at room temperature, for example, due to the lower viscosity. The functionality of the damping element 34 is therefore reduced even before reaching the elastomer point [sic] of the elastomer 36. At “moderately” cold temperatures above −20° C., for example, this may under some circumstances result in an increase in CO emissions by the vehicle heater caused by pulsations in the fuel system. At extremely low temperatures of less than −30° C., for example, the problem may even occur that stabilization of combustion operation is prevented due to pulsations in the fuel system. Although it is possible to start the burner in such cases, the burner may become destabilized over a period of time or may even be extinguished after the glow plug goes out, i.e., when there is no supporting energy for the base of the flame. Such unwanted extinction of the flame may occur, for example, within 0 to 5 minutes after turning off the glow plug. ¹ TN: The source consistently uses “Artikdiesel” when the term is properly “Arctic diesel”—as done here without comment below.

The object of the present invention is to improve upon the generic reciprocating piston fuel pumps and the generic methods so that the problems described above are avoided and pulsation-free pumping of fuel is possible even at temperatures below −20° C., for example.

This object is achieved through the features of the independent claims.

Advantageous embodiments and refinements of the invention are derived from the dependent claims.

The inventive reciprocating piston fuel pump is based on the generic state of the art in that means are provided for heating the elastomer. Heating of the elastomer by Δx° C. until reaching the full-load point corresponds to a direct expansion/reduction of the effective operating range of the damping element and thus in particular the characteristics map of the burner of the automotive heater by the same number Δx° C. into the negative temperature range. Due to this inventive approach, operation of an automotive heater with Arctic diesel at −30° C., for example, is possible. Due to the heated elastomer, which is therefore softer, the pulsation intensity in the fuel system is lower, so that the burner of an automotive heater can be operated under more stable conditions and thus with a more uniform and quieter combustion noise at moderately low temperatures of more than −20° C., for example (pulsations generate a “rough” combustion noise). In conjunction with automotive heaters, for example, the tendency to flame separation when the temperature falls below a certain limit temperature of −25° C., for example, is shifted toward lower temperatures due to the lower pulsations. At “higher” temperatures of 0° C. of −20° C., for example, a reduction in CO emissions can be achieved with automotive heaters using both Arctic diesel and winter diesel due to the lower pulsations.

The inventive reciprocating piston fuel pump has been improved upon advantageously due to the fact that the means for heating the elastomer comprise an electric heater. The electric heater may be operated both directly and indirectly. For example, a heating wire introduced into the elastomer material may be provided, such as that known for heating windshields of vehicles as well as for ski equipment and other equipment. Before the start of the actual pumping of fuel, the heating wire preferably receives an electric current so that the limit temperature for the required minimum elasticity is exceeded at the start of fuel pumping. The actual heating, however, may also include heating elements, e.g., PTC heating elements, which are provided for heating liquid fuel inside the reciprocating piston fuel pump. One or more such heating elements may be connected in parallel with the winding of the electromagnet, for example. Separate triggering is of course also possible. For example, PTC heating elements have a very high resistance-temperature coefficient. Therefore, in a cold start, the small amount of fuel in the pump is rapidly heated to a maximum temperature of 50° C., for example. At such a temperature level, the resistance of the heating conductor is so great that no mentionable heating output is delivered. The heated fuel then heats up the elastomer and consequently increases its elasticity. Additionally or alternatively, it is also possible for corresponding heating elements to be provided in proximity to the elastomer in order to heat it.

In addition, with the inventive reciprocating piston fuel pump, it is possible for the means for heating the elastomer to include a winding of the electromagnetic drive of the reciprocating piston fuel pump. The windings and/or magnetic coils of known reciprocating piston fuel pumps consume up to eight watts of power, for example, at low temperatures. This power is converted primarily to heat, and the heat can advantageously be utilized to heat the elastomer.

In this context, an advantageous embodiment of the inventive reciprocating piston fuel pump provides for a material having a low thermal conductivity to be provided in an area between the elastomer and the environment. In principle, any thermal insulation material with which those skilled in the art are familiar may be used as the material having a low thermal conductivity, e.g., foamed plastic and/or expanded metals. Due to such thermal insulation with respect to the environment, exhaust heat from the reciprocating piston fuel pump can advantageously be utilized to heat the elastomer. It is preferable here that not the entire reciprocating piston fuel pump but instead only the area of the damping element is insulated to avoid overheating other components of the reciprocating piston fuel pump.

Additionally or alternatively, with the inventive reciprocating piston fuel pump, it is possible for a material having a high thermal conductivity to be provided in an area between the winding and the elastomer. Metals in particular, e.g., aluminum, may be considered as the material having a high thermal conductivity. It is possible here for metal ribs or metal housing components in contact with the damping element to form one or more heat bridges.

The inventive method is based on the generic state of the art in that the elastomer is heated even before the burner is ignited. The time horizon of the starting phase of the automotive heater with glow plug support may amount to 2 minutes, for example. This period of time is minimally usable to achieve heating of the elastomer and in many cases is sufficient to achieve heating of the metering pump and then the elastomer due to the uptake of power by the heating elements which are provided. If the waste heat of the reciprocating piston fuel pump is used to heat the elastomer, overheating of the reciprocating piston fuel pump at higher temperatures is avoided because the power uptake is lower at higher temperatures.

In conjunction with the inventive method it is also possible in an advantageous manner for the elastomer to be heated by an electric heating device. The electric heating device may comprise in particular the components which have already been explained in conjunction with the electric heating device for the inventive reciprocating piston fuel pump. Reference is made to the respective discussion in order to avoid repetition here.

The same thing is also logically applicable to the case when in the inventive method the elastomer is heated by a winding of an electromagnetic drive of the reciprocating piston fuel pump.

Preferred embodiments of the invention are described in greater detail below as an example on the basis of drawings.

FIG. 1 shows a schematic sectional view of a known reciprocating piston fuel pump, which was already explained in the introduction;

FIG. 2 shows a schematic block diagram illustrating a vehicle heater comprising the inventive reciprocating piston fuel pump;

FIG. 3 shows a schematic sectional view of a first embodiment of an inventive reciprocating piston fuel pump;

FIG. 4 shows a schematic sectional view of a second embodiment of an inventive reciprocating piston fuel pump;

FIG. 5 shows a schematic sectional view of a third embodiment of an inventive reciprocating piston fuel pump;

FIG. 6 shows a schematic sectional view of a first embodiment of a fuel valve which may be part of the automotive heater from FIG. 2;

FIG. 7 shows a schematic sectional view of a second embodiment of a fuel valve which may be part of the automotive heater from FIG. 2;

FIG. 8 shows a schematic sectional view of a third embodiment of a fuel valve which may be part of the automotive heater from FIG. 2 and

FIG. 9 shows a schematic sectional view of a fourth embodiment of a fuel valve which may be part of the automotive heater from FIG. 2.

In the drawings the same or similar reference numerals are used to refer to the same or similar components which are explained only once in some cases to avoid repetition.

FIG. 2 shows a schematic block diagram illustrating a vehicle heater comprising the inventive reciprocating piston fuel pump. The automotive heater illustrated here may be an additional heater or an auxiliary heater, for example. The automotive heater 10 illustrated here includes the inventive reciprocating piston fuel pump 16 with the help of which liquid fuel can be pumped from a fuel tank 12 to a burner/heat exchanger unit 14. Depending on whether it is air heating or water heating, the burner/heat exchanger unit 14 is connected to other air and/or water lines (not shown), as those skilled in the art will be well aware. The burner/heat exchanger unit 14 also includes a fuel valve 52 and/or 84 with which the fuel supply may be shut down entirely or partially. This fuel valve 52 and/or 84 need not necessarily be integrated into the burner/heat exchanger unit 14 but instead may also be arranged between the reciprocating piston fuel pump 16 and the burner/heat exchanger 14.

The reciprocating piston fuel pump 16 illustrated in FIG. 3 is intended for pumping liquid fuel in the direction represented by the arrows, namely from a fuel inlet 18 to a fuel outlet 20. As soon as a suitable voltage is applied to an electric terminal 42, electricity flows through a winding 22 so that movement of a reciprocating piston 24 is electromagnetically induced. First liquid fuel in a pump chamber 30 is ejected through a nonreturn valve 28 against the hydraulic resistance of the output line. Thereafter, the electric current through the winding 22 is terminated. A restoring spring 26 forces the reciprocating piston 24 toward the left into its resting position. In doing so, liquid fuel is drawn in through an intake valve 32 and the pump chamber 30, thereby filling the pump chamber. With this pump delivery principle, it is also possible to convey even fuels having a very low viscosity but to do so with precision volumetrically, as mentioned in the introduction, so that the delivery rate can be controlled accurately via the frequency of the triggering voltage pulses.

To at least partially suppress the pulsations that occur during operation of the reciprocating piston fuel pump, the damping element 34 mentioned in the introduction is provided, comprising a bellows-like elastomer 36. When liquid fuel passes through a borehole 40 and comes in contact with the elastomer 36, the elastomer 36 expands into a neighboring chamber 38 which is provided in a damper housing formed by a molded plastic part 44. The prerequisite for this is a certain backpressure in the fuel system which ensures that the elastomer 36 will be “secured” in place. To this extent the reciprocating piston fuel pump shown in FIG. 3 corresponds to the known reciprocating piston fuel pump illustrated on the basis of FIG. 1.

However, the embodiment of the inventive reciprocating piston fuel pump 16 shown in FIG. 3 has an electric heater 16 to heat the elastomer 36. In the case presented here, the electric heater 46 includes a plurality of PTC heating elements 46a arranged near the elastomer 36, at least one heating wire 46b which is integrated into the elastomer 36, and two PTC heating elements 46c arranged in the vicinity of pump chamber 30. It is clear that not all the heating elements 46a, 46b and 46c presented here need necessarily be present but instead it may optionally be sufficient to provide only one type of heating element 46a, 46b or 46c to heat the elastomer 36 suitably. To optimize the effect of the PTC heating element 46a and 46c, it is advantageous if a material having a high thermal conductivity, e.g., a metal is provided between the area to be heated, i.e., the elastomer 36 and/or the pump chamber 30 and the respective PTC heating element. The most direct heating of the elastomer 36 is achieved by the heating wire(s) 46b. Heating of the fuel by the PTC heating element 46c is advantageous not only for heating of the elastomer 36 but also preheating of the fuel allows better combustion. The PTC heating elements 46a represent a compromise inasmuch as they heat the material that comes in contact with the elastomer 36 as well as the material that comes in contact with the liquid fuel. Some or all of the heating elements 46a, 46b, 46c presented here may be connected to the winding 22 in parallel or triggered separately. Separate triggering is more complex but it allows preheating to be performed independently of pump operation.

The embodiment of the inventive reciprocating piston fuel pump 16 shown in FIG. 4 differs from the embodiment according to FIG. 3 in that no heating elements are provided there but instead the elastomer 36 is heated by the waste heat of the reciprocating piston fuel pump 16. To permit this heating and/or to optimize it, the area of the damping element 36 is surrounded by a material 50 having a low thermal conductivity, i.e., is surrounded by thermal insulation. Although this is not shown here, the material 50 having a low thermal conductivity may optionally have a layered structure. In any case it is preferable for the reciprocating piston fuel pump 16 not to be surrounded entirely with insulation material because this could result in overheating of the reciprocating piston fuel pump in particular at higher outside temperatures.

The embodiment of the reciprocating piston fuel pump 16 shown in FIG. 5 differs from the embodiment according to FIG. 3 in that no heating elements are provided there but instead the heating of the elastomer 36 is accomplished by the heat generated in the winding 22. To this end, a material 48 having a high thermal conductivity is provided between the winding 22 and the elastomer 36. The material 48 having a high thermal conductivity may be a metal such as aluminum in particular, in which case the metal may be shaped in the form of ribs, for example, to create a suitable heat bridge. Although this is not shown here, it may also be advantageous to place the heat bridge in areas that come in contact with the liquid fuel so as to heat the fuel. However, in the case illustrated here, the material 48 having a high thermal conductivity is integrated in the form of metal ribs into the molded plastic part 44 and heats only the elastomer 36.

It will be clear to those skilled in the art that the embodiments of the inventive reciprocating piston fuel pump explained with reference to FIGS. 3 through 5 may be combined with one another in any desired manner and all of these possible combinations are herewith disclosed.

It will be also be clear that the inventive method for starting and operating an automotive heater that is operated with liquid fuel, e.g., the automotive heater 10 shown in FIG. 2, may be performed with all the embodiments of the inventive reciprocating piston fuel pump described above by heating the elastomer 36 already before the ignition of the burner 14 (FIG. 2). If heat generated via the winding 22 is used for heating the elastomer 36, it may be appropriate to apply only a comparatively weak electric current to the winding 22 prior to ignition of the burner, namely so that a quantity of heat sufficient to heat the elastomer 36 is generated without starting the movement of reciprocating piston 24.

FIG. 6 shows a schematic sectional view of a first embodiment of a fuel valve 52 which may be part of the automotive heater 10 from FIG. 2. The fuel valve 52 is an electromagnetically operated coaxial valve which has a fuel inlet 54 and a fuel outlet 56. As soon as a suitable voltage is applied to an electric terminal 74, electricity flows through a winding 58 so that a valve piston 60 is set in motion to the right based on the diagram in FIG. 6 so that the fuel valve 52 is opened and fuel can flow from the fuel inlet 54 to the fuel outlet 56. In the currentless state of the winding 58, a restoring spring 62 presses the valve piston 60 to the left based on a diagram in FIG. 6 so that the valve piston 60 cooperates with a valve seat 64 to close the fuel valve 52.

Although in many cases it is sufficient to equip the reciprocating piston fuel pump itself with a damping element, the fuel valve 52 shown in FIG. 6 has an additional damping element 66 which also contributes toward suppressing pulsations in the fuel system. The damping element 66 also includes a bellows-like elastomer 68 in this case. When liquid fuel passes through a borehole 72 and comes in contact with the elastomer 68, the elastomer 68 expands into a neighboring chamber 70 which is provided in a damper housing formed by a molded plastic part 76. The prerequisite for this is a certain backpressure in the fuel system which ensures that the elastomer 68 will be “secured” in place.

To prevent the elastomer 68 which is made of the material FKN², for example, from undergoing a glass transition even at the very low temperatures of less than −23° C., for example, the damping element 66 is provided with an electric heater 78. In the case presented here, the electric heater 78 includes a plurality of PTC heating elements 78a which are arranged near the elastomer 68 and at least one heating wire 78b which is integrated into the elastomer 68. It is clear that not all the heating elements 78a and 78b illustrated here need be present but instead optionally only one type of heating element 78a or 78b may be sufficient to suitably heat the elastomer 68. To optimize the effect of the PTC heating elements 78a, it is advantageous if a material having a high thermal conductivity, e.g., a metal is provided between the area to be heated, i.e., the elastomer 36 and the respective PTC heating element. Direct heating of the elastomer 68 is achieved by the heating wires 78b. The PTC heating elements 78a heat up both the material that comes in contact with the elastomer 68 and the material that comes in contact with the liquid fuel. Preheating of fuel serves to provide indirect heating of the elastomer 68 and leads to better combustion. Other heating elements (not shown) may optionally also be provided, serving exclusively to heat the liquid fuel. Some or all of the heating elements 78a and 78b shown here may be connected in parallel to the winding 58 or may be triggered separately. Separate triggering is more complex but it allows reheating independently of the valve setting. ² TN: abbreviation of unknown expansion (“F” likely stands for “Faser” (fiber) and “K” for “Kunststoff” (plastic)).

The fuel valve 52 shown in FIG. 7 differs from the embodiment according to FIG. 6 in that no heating elements are provided there but instead the elastomer 68 is heated by the waste heat from the fuel valve 52. To permit this heating and/or to optimize it, the area of the damping element 66 is surrounded by a material 82 having a low thermal conductivity, i.e., thermal insulation. Although this is not shown here, the material 82 having the low thermal conductivity may optionally have a layered design. It is clear that when the fuel valve 52 is open, sufficient waste heat is generated due to the corresponding electric current applied to the winding 58 to heat the elastomer 68. However, the fuel valve 52d may also be designed in such a way that a low level of electric current through the winding 58 which is not sufficient to open the fuel valve 52d is sufficient to heat the elastomer 68.

The embodiment of the fuel valve 52 shown in FIG. 8 differs from the embodiment according to FIG. 6 in that no heating elements are provided there but instead the heating of the elastomer is accomplished by the heat generated in the winding 58 and by the heat carried over at least one heat bridge to the elastomer 68. To this end a material 80 having a high thermal conductivity is provided between the winding 58 and the elastomer 68. The material 80 having a high thermal conductivity may be in particular a metal such as aluminum, in which case the shaping may be in the form of ribs, for example, to create a suitable heat bridge. Although this is not shown here, it may also be advantageous to place the heat bridge in areas that come in contact with the liquid fuel in order to heat the fuel. In the case depicted here, the material 80 having a high thermal conductivity is integrated in the form of metal ribs into the molded plastic part 76 and heats at least primarily only the elastomer 68.

It will be cleared to those skilled in the art that the embodiment of the fuel valve 52 explained with reference to FIGS. 6 through 8 may also be combined with one another in any manner and all of these possible combinations are also disclosed here.

FIG. 9 shows a schematic sectional view of another embodiment of a fuel valve 84 which may be part of the automotive heater 10 from FIG. 2 instead of the fuel valve 52 explained above. In the case of the fuel valve 84, it is an electromagnetically operated coaxial valve that has a fuel inlet 86 and a fuel outlet 88. As soon as a suitable voltage is applied to an electric terminal 98, electricity flows through a winding 90, so that a valve piston 92 is set in motion toward the right based on the diagram in FIG. 9 so that the fuel valve 84 opens and fuel can flow from the fuel inlet 86 to the fuel outlet 88. In the currentless state of the winding 90 a restoring spring 94 presses the valve piston 92 to the left based on the diagram in FIG. 9 so that the valve piston 92 cooperates with a valve seat 96 to close the fuel valve 84.

The fuel valve 84 shown in FIG. 9 is designed to preheat fuel. For preheating the fuel, heat generated by the winding 90 is used, with a material 88 having a high thermal conductivity being provided between the winding 90 and the area with which the fuel comes in contact. The material 88 having a high thermal conductivity may be in particular a metal such as aluminum. Heating of the fuel is optimized by providing a material 100 which has a low thermal conductivity, i.e., a thermal insulator, in the outside area of the fuel valve 84. The material 100 having a low thermal conductivity may in principle be formed by any insulation material with which those skilled in the art are familiar, e.g., expanded metal and/or plastic foam. Although this is not shown here, the material 100 having a low thermal conductivity may also have a layered structure. It is clear that when the fuel valve 84 is open, sufficient waste heat is generated due to the corresponding electricity flowing through the winding 90 to preheat the fuel. However, the fuel valve 84 may also be designed so that, even if a lower current flow through the winding 90 is not sufficient to open the fuel valve 84, it is still sufficient to preheat the fuel.

Due to the use of the fuel valve 84 shown in FIG. 9, it may optionally be possible to omit a heating cartridge which is generally used. Such heating cartridges often have a high power consumption of 40 watts, for example, and therefore do not receive electric power during the entire burning operation of the automotive heater but instead only during the startup phase. In contrast with that, the fuel may be preheated during the entire burner operation with fuel valve 84, and fuel valve 84 may have an increased electric power consumption, if necessary. The fuel heating results in an increase in the enthalpy of the fuel and a reduction in viscosity, which has a positive effect on combustion operation.

The features of the present invention disclosed in the preceding description and in the drawings and claims may be essential to the embodiment of the invention either individually or in any combination.

LIST OF REFERENCE NUMERALS

• 10 Automotive heater
• 12 Fuel tank
• 14 Burner/heat exchanger unit
• 16 Reciprocating piston fuel pump
• 18 Fuel inlet
• 20 Fuel outlet
• 22 Winding
• 24 Reciprocating piston
• 26 Restoring spring
• 28 Nonreturn valve
• 30 Pump chamber
• 32 Intake valve
• 34 Damping element
• 36 Elastomer
• 38 Chamber
• 40 Bore
• 42 Electric terminal
• 44 Molded plastic part
• 46 Heating element
• 48 Material having a high thermal conductivity/metal rib
• 50 Material having a low thermal conductivity/insulator
• 52 Fuel valve
• 54 Fuel inlet
• 56 Fuel outlet
• 58 Winding
• 60 Valve piston
• 62 Restoring spring
• 64 Valve seat
• 66 Damping element
• 68 Elastomer
• 70 Chamber
• 72 Bore
• 74 Electric terminal
• 76 Molded plastic part
• 78 Heating element
• 80 Material having a high thermal conductivity/metal rib
• 82 Material having a low thermal conductivity/insulator
• 84 Fuel valve
• 86 Fuel inlet
• 88 Fuel outlet
• 90 Winding
• 92 Valve piston
• 94 Restoring spring
• 96 Valve seat
• 98 Electric terminal
• 100 Molded plastic part/insulator

Claims

1. Reciprocating piston fuel pump (16), in particular for an automotive heater (10) which is driven electromagnetically and is provided for delivering liquid fuel, having a damping element (34) comprising an elastomer (36) for damping pulsations created by the reciprocating piston fuel pump (16), characterized in that means (22, 46, 48, 50) are provided for heating the elastomer (36).

2. Reciprocating piston fuel pump according to claim 1, characterized in that means (22, 46, 48, 50) for heating the elastomer comprise and electric heater (46).

3. Reciprocating piston fuel pump according to claim 1 or 2, characterized in that the means (22, 46, 48, 50) for heating the elastomer comprise a winding (22) of the electromagnetic drive of the reciprocating piston fuel pump (16).

4. Reciprocating piston fuel pump according to any one of the preceding claims, characterized in that a material (50) having a low thermal conductivity is provided in an area between the elastomer (36) and the environment.

5. Reciprocating piston fuel pump according to claim 3, characterized in that material (48) having a high thermal conductivity is provided in an area between the winding (22) and the elastomer (36).

6. Method for starting and operating an automotive heater (10) that is operated with liquid fuel and has a burner (14) and a reciprocating piston fuel pump (16) with a damping element (34) comprising an elastomer (36) for damping pulsations created by the reciprocating piston fuel pump (16), characterized in that the elastomer (36) is already heated before ignition of the burner (14).

7. Method according to claim 6, characterized in that the elastomer (36) is heated by an electric heating device (46).

8. Method according to claim 6 or 7, characterized in that the elastomer (36) is heated by a winding (22) of an electromagnetic drive of the reciprocating piston fuel pump (16).