KR20070119062A - Reciprocating piston fuel pump and method for starting and operating an automotive heater - Google Patents

Abstract

The invention relates to a lifting piston fuel pump (16), especially for a motor vehicle heating system (10), that is electromagnetically driven and used to transport liquid fuel. Said fuel pump comprises a damping element (34) which is provided with an elastomer (36) and is used to damp pulsations generated by the lifting piston fuel pump (16). According to the invention, means (22, 46, 48, 50) are provided for heating the elastomer (36). The invention also relates to a method for starting and operating a motor vehicle heating system (10) operated by liquid fuel, said heating system comprising a burner (14) and a lifting piston fuel pump (16) provided with a damping element (34) which comprises an elastomer (36) and is used to damp pulsations generated by the lifting piston fuel pump (16). The elastomer (36) is heated before the ignition of the burner (14).

Description

How to start and operate a reciprocating piston fuel pump and car heater {RECIPROCATING PISTON FUEL PUMP AND METHOD FOR STARTING AND OPERATING AN AUTOMOTIVE HEATER}

The present invention relates to a reciprocating piston fuel pump, more particularly electromagnetically driven, provided for pumping liquid fuel, and having a damping member for reducing the pulsation generated by the reciprocating piston fuel pump, including an elastomer. It relates to a reciprocating piston fuel pump for an automobile heater.

The invention also provides for starting and operating an automobile heater comprising a reciprocating piston fuel pump having a burner and having a damping member including an elastomer to reduce pulsation generated by the reciprocating piston fuel pump. It is about a method.

Typical reciprocating piston fuel pumps are described, for example, in the paper Fahrzeung- und Verkehrstechnik, Technische Mitteilungen [Automotive and Traffic Engineering, Technical Report] 97 (2004), No. 1, 9-11, which is shown in schematic cross section in FIG.

A reciprocating piston fuel pump 16 ′ shown in FIG. 1 is provided for pumping liquid fuel from the fuel inlet 18 to the fuel outlet 20 in the direction indicated by the arrow. As soon as a suitable voltage is applied to the electrical terminal 42, electricity flows through the winding 22 to electromagnetically induce the movement of the reciprocating piston 24. First, fuel in the pump chamber 30 is discharged through the non-return valve 28 against the fluid resistance of the discharge pipe. Then, the current through the winding 22 is cut off. The return spring 26 pushes the reciprocating piston 24 to the left to the rest position. Liquid fuel is drawn through the intake valve 32 to fill the pump chamber 30. According to this pump principle, very precise fuel delivery in volumetric terms is also possible, and very low viscosity fuels are also possible. The carrying amount can be precisely adjusted via the frequency of the triggering voltage pulse.

However, unwanted pulsation occurs in the fuel system due to the forward and backward movement of the reciprocating piston 24. In order to at least partially suppress such pulsations, it is already known to provide a damping member 34 comprising a blower-shaped elastomer 36. When the liquid fuel passes through the borehole 40 and contacts the elastomer 36, the elastomer 36 extends into an adjacent chamber 38 provided inside the damper housing formed by the molded plastic portion 44. An essential condition for this is the specific back pressure in the fuel system which causes the elastomer 36 to "settle" in place.

One of the problems with the reciprocating piston fuel pump 16 ′ shown in FIG. 1 is that the damping member 34 does not function at an external cold, for example, below -23 ° C., which causes the elastomer 36 () Is the common elastomer point (glass transition point) of the elastomer 36, for example -23 ° C.) Because it is cured or undergo a glass transition. Another problem is the only fuel approved for use at diesel temperatures below -20 ° C for diesel burners, because of the low viscosity of the so-called Arctic diesel, temperatures below -20 ° C below the back pressure that winter diesel produces at room temperature. At much lower back pressure. Thus, the functionality of the damping member 34 is reduced even before reaching the elastomeric point of the elastomer 36. Occasionally, at " moderately " cold temperatures, such as temperatures above -20 ° C, pulsations in the fuel system may increase CO emissions by automotive heaters. At extremely low temperatures, such as below −30 ° C., pulsations in the fuel system sometimes lead to problems of stabilization of combustion operations. In such a case, it is possible to start the burner, but it is extinguished after the burner has destabilized after a certain time or after the glow plug has been switched off, ie when there is no energy supporting the base of the flame. Such unwanted flame extinction occurs, for example, within 0-5 minutes after the glow plug is turned off.

It is an object of the present invention to avoid the above problems and to improve the general reciprocating piston fuel pump and its method, for example, to enable pumping of fuel without pulsation even at temperatures below -20 ° C.

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

Preferred embodiments and detailed description of the invention are derived from the dependent claims.

The novel reciprocating piston fuel pump conforms to the general state of the art in that means are provided for heating the elastomer. Heating the elastomer to Δx ° C. until reaching the highest load point corresponds to a direct extension / reduction of the effective operating range of the damping member, thus in particular the characteristic map of the burner of the automobile heater to a negative temperature range of the same value Δx ° C. corresponds to expansion / contraction in the negative temperature range. Thanks to this novel approach, it is possible for automotive heaters to be operated with arctic diesel at -30 ° C. Due to the heated softer elastomer, the pulsation intensity in the fuel system is lowered so that the burner of the car heater can be operated under more stable conditions, so that the pulsation produces "noisy" combustion noise, for example -20 ° C. At moderately low temperatures, the combustion noise becomes more constant and calmer. In an automobile heater, when the temperature is below a predetermined limit temperature, for example, -25 ° C, the flame separation tends to move toward a lower temperature because of the lower pulsation. For example, at " higher " temperatures of 0 to -20 [deg.] C., CO emissions can be reduced with automotive heaters using both polar and winter diesels due to lower pulsations.

The novel reciprocating piston fuel pump has been advantageously improved due to the fact that the means for heating the elastomer comprises an electric heater. The electric heater can be operated both directly and indirectly. For example, heating wires introduced into the elastomeric material, such as ski equipment and other equipment, as well as heating wires known for heating the windshield of an automobile can be provided. Prior to actually pumping the fuel, it is desirable that the heating wire receive current so that the limit temperature for the minimum required elasticity is exceeded at the start of fuel pumping. In actual heating, however, it is also possible to include a heating element, for example a PTC heating element provided for heating liquid fuel in a reciprocating piston fuel pump. One or more such heating elements can be connected, for example, in parallel with the winding of the electromagnet. Of course, individual triggering is also possible. For example, PTC heating means have a very high resistance-temperature coefficient. Thus, when starting at cold temperatures, a small amount of fuel in the pump is heated up to a maximum temperature of, for example, 50 ° C. At this temperature level, the resistance of the heating conductors is so great that no heating output worth mentioning is carried. The heated fuel then heats up the elastomer, thereby increasing its elasticity. Additionally or alternatively, the heating element may be provided in close proximity to the elastomer to heat the elastomer.

Thus, in the novel reciprocating piston fuel pump, it is possible that the means for heating the elastomer comprises a winding of an electromagnetically driven reciprocating piston fuel pump. The windings and / or magnetic coils of known reciprocating piston fuel pumps consume power at low temperatures, for example up to 8 watts. This power source is mainly converted to heat, which heat can advantageously be used to heat the elastomer.

In such a situation, a preferred embodiment of the novel reciprocating piston fuel pump provides a material having a low thermal conductivity to be provided in the region between the elastomer and the external environment. Primarily, thermal insulation materials well known to those skilled in the art can use materials having low thermal conductivity, such as foamed plastics and / or expanded metals. Due to this thermal insulation to the external environment, exhaust heat from the reciprocating piston fuel pump can be advantageously used to heat the elastomer. Here, it is preferable to prevent the overheating of other elements of the reciprocating piston fuel pump by insulating only the region of the damping member instead of the entire reciprocating piston fuel pump.

Additionally or alternatively, in the novel reciprocating piston fuel pump, a material with high thermal conductivity can be provided in the region between the winding and the elastomer. Metals, in particular materials with high thermal conductivity, such as aluminum, can be considered. Here, it is possible for a metal rib or metal housing element in contact with the damping member to form one or more heat bridges.

The novel method follows the general state of the art in that the elastomer is heated before the burner is ignited. The time range of the start-up phase of the motor vehicle heater with the glow plug support can be for example two minutes. This time range is the minimum time that can be used to heat the elastomer, and in most cases is sufficient time to heat the metering pump and then the elastomer due to absorption of power by the heating element 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 prevented because power absorption is lower at higher temperatures.

In the novel process, an advantageous manner is also possible in which the elastomer is heated by an electric heating device. The electric heating device may comprise elements which have already been described, in particular with respect to the electric heating device for the novel reciprocating piston fuel pump. Each element refers to the foregoing description in order to avoid duplication.

In principle, the same can also be applied to the case in which the elastomer is heated by the winding of an electromagnetically driven reciprocating piston fuel pump.

Preferred embodiments of the invention are described in detail below by way of example on the basis of the drawings.

1 is a schematic cross-sectional view of a known reciprocating piston fuel pump, already described herein.

2 is a schematic block diagram illustrating a motor vehicle heater including the novel reciprocating piston fuel pump.

3 is a schematic cross-sectional view showing a first embodiment of the novel reciprocating piston fuel pump.

4 is a schematic cross-sectional view showing a second embodiment of the novel reciprocating piston fuel pump.

5 is a schematic cross-sectional view showing a third embodiment of the novel reciprocating piston fuel pump.

6 is a schematic cross-sectional view showing a first embodiment of a fuel valve that is part of the automobile heater of FIG. 2.

FIG. 7 is a schematic cross-sectional view illustrating a second embodiment of a fuel valve that is part of the automobile heater of FIG. 2.

8 is a schematic cross-sectional view showing a third embodiment of a fuel valve that is part of the automobile heater of FIG. 2.

9 is a schematic cross-sectional view showing a fourth embodiment of a fuel valve that is part of the automobile heater of FIG. 2.

In the drawings, the same or similar reference numerals are used to refer to the same or similar components already mentioned once in order to avoid duplication.

2 is a schematic block diagram illustrating a motor vehicle heater including the novel reciprocating piston fuel pump. The motor vehicle heater shown in this figure may be, for example, an additional heater or an auxiliary heater. The automotive heater shown in this figure includes a novel reciprocating piston fuel pump 16 that helps liquid fuel to be pumped from the fuel tank 12 to the burner / heat exchange device 14. As is well known to those skilled in the art, upon warm air heating or hydrothermal, the burner / heat exchange device 14 is connected with other air lines and / or water lines (not shown). Burner / heat exchange device 14 also includes a fuel valve 52 and / or 84 that blocks the fuel supply in whole or in part. Such fuel valves 52 and / or 84 need not necessarily be integrally formed with burner / heat exchanger 14, but instead between reciprocating piston fuel pump 16 and burner / heat exchanger 14. It may be arranged.

The reciprocating piston fuel pump 16 shown in FIG. 3 is for pumping liquid fuel from the fuel inlet 18 to the fuel outlet 20 in the direction indicated by the arrow. As soon as a suitable voltage is applied to the electrical terminal 42, electricity flows through the winding 22 to electromagnetically induce the movement of the reciprocating piston 24. First, the first liquid fuel in the pump chamber 30 is discharged through the non-return valve 28 against the fluid resistance of the output line. Then, the current through the winding 22 is cut off. The return spring 26 forces the reciprocating piston 24 to the left to the rest position. By doing so, the liquid fuel is drawn through the intake valve 32 and the pump chamber 30 to fill the pump chamber. According to this pump principle, as described above, it is also possible not only to carry fuel with very low viscosity, but also to carry it in a volumetric and precise manner, wherein the carrying ratio can be precisely adjusted through the frequency of the starting voltage pulses. Can be.

In order to at least partially suppress the pulsation occurring during operation of the reciprocating piston fuel pump, the damping member 34 described above is provided at the beginning including the blower-shaped elastomer 36. When the liquid fuel passes through the borehole 40 and contacts the elastomer 36, the elastomer 36 extends into an adjacent chamber 38 provided inside the damper housing formed by the molded plastic portion 44. An essential condition for this is the specific back pressure in the fuel system which causes the elastomer 36 to "settle" in place. In this respect, the reciprocating piston fuel pump shown in FIG. 3 is similar to the known reciprocating piston fuel pump, shown based on FIG. 1.

However, the embodiment of the novel reciprocating piston fuel pump 16 shown in FIG. 3 has an electric heater 46 that heats the elastomer 36. In the case described in this embodiment, the electric heater 46 includes a plurality of PTC heating elements 46a disposed in the vicinity of the elastomer 36, at least one heating wire 46b integrally formed with the elastomer 36, and Two PTC heating elements 46c disposed near the pump chamber 30. It is not necessary to include all of the heating elements 46a, 46b and 46c described in this embodiment, but instead of selectively including any one of the heating elements 46a, 46b and 46c, the elastomer 36 It will be appreciated that it may be sufficient to adequately heat the. In order to optimize the effect of the PTC heating elements 46a and 46c, a material having a high thermal conductivity, ie the area where the metal is to be heated, such as the elastomer 36 and / or the pump chamber 30 and the respective PTC heating element It is advantageous if it is provided between. The most direct heating of the elastomer 36 is by heating wire (s) 46b. The heating of the fuel by the PTC heating element 46c is advantageous not only for the heating of the elastomer 36 but also for preheating of the fuel, which enables better combustion. PTC heating element 46a represents an intermediate as long as it heats the material in contact with the elastomer 36 as well as the material in contact with the liquid fuel. Some or all of the heating elements 46a, 46b, 46c shown in this figure are connected in parallel with the winding 22 or triggered separately. Individual triggers are more complex but allow preheating separately from pump operation.

The embodiment of the novel reciprocating piston fuel pump 16 shown in FIG. 4 is according to FIG. 3 in that no heating element is provided but instead the elastomer 36 is heated by the waste heat of the reciprocating piston fuel pump 16. It differs from an Example. In order to permit and / or optimize this heating, the area of the damping member 36 is surrounded by a material having low thermal conductivity, ie surrounded by a thermal insulating material. Although not shown in this figure, the material 50 with low thermal conductivity optionally has a layer structure. In any case, the reciprocating piston fuel pump 16 is preferably not completely surrounded by insulating material, since this leads to overheating of the reciprocating piston fuel pump, especially at higher external temperatures.

The embodiment of the reciprocating piston fuel pump 16 shown in FIG. 5 does not provide a heating element but instead heats the elastomer 36 by means of heat generated in the winding 22. Is different from For this reason, 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 this case the metal may be formed in the form of a rib to make a suitable thermal bridge. Although not shown in FIG. 5, it may also be advantageous to locate the thermal bridges in contact with the liquid fuel to heat the fuel. However, in the case shown in this figure, the material 48 having high thermal conductivity is integrally formed in the form of metal ribs in the molded plastic portion 44 and only the elastomer 36 is heated.

It will be apparent to one skilled in the art that the embodiments of the novel reciprocating piston fuel pump described with reference to FIGS. 3 to 5 can be mutually coupled in a desired manner and all such possible combinations are disclosed herein.

A novel method of starting and operating a car heater operated with liquid fuel, such as the car heater shown in FIG. 2, is the novel reciprocation described above by preheating the elastomer 36 before ignition of the burner 14 (FIG. 2). It is also apparent that all embodiments of the piston fuel pump can be implemented. If the heat generated through the windings 22 is used to heat the elastomer 36, then enough heat to occur before ignition of the burner, ie without heating, commences the movement of the reciprocating piston 24. It may be appropriate to apply only a relatively weak current to the winding 22.

FIG. 6 shows a schematic cross-sectional view of a first embodiment of a fuel valve 52 that is part of the motor vehicle heater 10 of FIG. 2. The fuel valve 52 is an electromagnetically actuated coaxial valve having a fuel inlet 54 and a fuel outlet 56. When an appropriate voltage is applied to the electrical terminal 74, electricity flows through the windings 58 so that the valve piston 60 is set in motion to the right based on the diagram of FIG. 6, whereby the fuel valve 52 is opened and the fuel is fueled. It may flow from the inlet 54 to the fuel outlet 56. In the non-current state of the winding 58, the restoring spring 62 presses the valve piston 60 to the left based on the diagram of FIG. 6 so that the valve piston 60 works with the valve seat 64 to produce a fuel valve. Lock (52).

In many cases, the reciprocating piston fuel pump itself is sufficient to have one damping member, but the fuel valve 52 shown in FIG. 6 has an additional damping member that also contributes to suppressing pulsations in the fuel system. . In this case, the damping member 66 also includes a blower shaped elastomer 68. As the liquid fuel passes through the borehole 72 and contacts the elastomer 68, the elastomer 68 extends into an adjacent chamber 70 provided in a damper housing formed by the molded plastic portion 76. An essential condition for this is the specific back pressure in the fuel system which causes the elastomer 36 to "settle" in place.

For example, FKN ² The elastomer 68 made of material is provided with an electric heater 78 on the damping member 66, for example, to prevent it from undergoing a glass transition at very low temperatures below -23 ° C. In the case described in this embodiment, the electric heater 78 includes a plurality of PTC heating elements 78a arranged near the elastomer 68 and at least one heating line 78b integrally formed in the elastomer 68. Include. It is apparent that not all of the heating elements 78a and 78b shown in this figure need to be present, but instead, only one of the heating elements 78a or 78b is sufficient to adequately heat the elastomer. In order to optimize the effect of the PTC heating element 78a, it is advantageous if a material having a high thermal conductivity, such as a metal, is provided between the region to be heated, ie the elastomer 36 and each PTC heating element. Direct heating of the elastomer 68 is achieved by heating wire 78b. The PTC heating element 78a heats both the material in contact with the elastomer 36 and the material in contact with the liquid fuel. Preheating of the fuel provides indirect heating of the elastomer 68 and leads to better combustion. Other heating elements (not shown) may optionally be provided for dedicated liquid fuel heating. Some or all of the heating elements 78a and 78b shown in this figure are connected in parallel with the winding 58 or triggered separately. Individual triggers are more complex but allow reheating independently of valve setting.

The fuel valve 52 shown in FIG. 7 differs from the embodiment according to FIG. 6 in that no heating element is provided but instead the elastomer 68 is heated by waste heat from the fuel valve 52. In order to permit and / or optimize this heating, the area of damping member 66 is surrounded by a material 82 having low thermal conductivity, ie a thermal insulating material. Although not shown in this figure, the material 82 having low thermal conductivity may optionally have a layer structure. When the fuel valve 52 is opened, it is obvious that sufficient waste heat is generated to heat the elastomer 68 due to the corresponding current applied to the windings 58. However, fuel valve 52 may also be designed such that a low level of current, which is not sufficient to open fuel valve 52, through winding 58 is sufficient to heat elastomer 68.

The embodiment of the fuel valve 52 shown in FIG. 8 is provided in that the heating element is not provided but instead is heated by the heat generated in the windings 58 and the heat transferred to the elastomer 68 in at least one thermal bridge. Different from the embodiment according to FIG. 6. Because of this, a material 80 having high thermal conductivity is provided between the winding 58 and the elastomer 68. The material 80 having high thermal conductivity may be a metal in particular, such as aluminum, in which case it may be formed in the form of a rib, for example, to make a suitable thermal bridge. Although not shown in this figure, it may also be advantageous to locate the thermal bridges in areas that are in contact with the liquid fuel to heat the fuel. In the case described in this embodiment, the material 80 having high thermal conductivity is integrally formed in the form of metal ribs in the molded plastic portion 76 and at least mainly heats the elastomer 68.

It will be apparent to one skilled in the art that the embodiments of the fuel valve 52 described with reference to FIGS. 6 to 8 may also be interconnected in any way, all such possible combinations are disclosed herein.

9 shows a schematic cross-sectional view of another embodiment of a fuel valve 84 that is part of the automotive heater 10 of FIG. 2 instead of the fuel valve 52. The fuel valve 84 is an electromagnetically actuated coaxial valve having a fuel inlet 86 and a fuel outlet 88. When an appropriate voltage is applied to the electrical terminal 98, electricity flows through the winding 90 so that the valve piston 92 is set to move to the right based on the diagram of FIG. 9 so that the fuel valve 84 is opened and the fuel is It may flow from the fuel inlet 86 to the fuel outlet 88. In the non-current state of the winding 90, the restoring spring 94 urges the valve piston 92 to the left based on the diagram of FIG. 9 so that the valve piston 92 operates with the valve seat 96 to provide a fuel valve. Lock (84).

The fuel valve 84 shown in FIG. 9 is designed to preheat the fuel. In order to preheat the fuel, a material 88 of high thermal conductivity is provided between the winding 90 and the area where the fuel is in contact and the heat generated by the winding 90 is used. The material 88 having high thermal conductivity may be a metal in particular, such as aluminum. The heating of the fuel is optimized by providing a low thermal conductivity material 100, ie a thermal insulation material, to the outer region of the fuel valve 84. The material 100 having low thermal conductivity may be formed mainly by insulating materials, such as expanded metal and / or foamed plastics, which are well known to those skilled in the art. Although not shown in this figure, the material 100 with low thermal conductivity may also have a layered structure. When the fuel valve 84 is open, it is apparent that the corresponding electricity flowing through the winding 90 generates sufficient waste heat to preheat the fuel. However, the fuel valve 84 can be designed to be sufficient to preheat the fuel even if the lower current flow through the winding 90 is not sufficient to open the fuel valve 84.

Thanks to the use of the fuel valve 84 shown in FIG. 9, it is alternatively possible to omit a commonly used heating cartridge. Such heating cartridges usually have a high power consumption, for example 40 watts, and therefore do not receive power during the ignition operation of the car heater and instead receive power only during the startup phase. In contrast, fuel may be preheated to fuel valve 84 throughout burner operation, and if desired, fuel valve 84 may have increased power consumption. Heating of the fuel results in an increase in enthalpy and a decrease in viscosity of the fuel, which has a positive effect on the combustion operation.

The features of the invention disclosed in the foregoing description, as well as the drawings and claims, are alone or in combination and are very important to the completion of the invention.

Claims (8)

A reciprocating piston fuel pump (16), which is electromagnetically driven and provided for carrying liquid fuel, in particular a reciprocating piston fuel pump (16) for an automotive heater (10), comprising an elastomer (36) including the reciprocating piston fuel pump ( In a reciprocating piston fuel pump (16) having a damping member (34) that reduces the pulsation generated by 16, means (22, 46, 48, and 50) are provided to heat the elastomer (36). Reciprocating piston fuel pump, characterized in that 16. The method of claim 1, Reciprocating piston fuel pump, characterized in that the means (22, 46, 48 and 50) for heating the elastomer comprise an electric heater (46). The method according to claim 1 or 2, Reciprocating piston fuel pump, characterized in that the means (22, 46, 48 and 50) for heating the elastomer comprise a winding (22) of the reciprocating piston fuel pump (16) which is electromagnetically driven. The method of claim 1, wherein A low thermal conductivity material (50) is provided in the region between the elastomer (36) and the external environment. The method of claim 3, A high thermal conductivity material (48) is provided in the region between the winding (22) and the elastomer (36). In a method of starting and operating an automotive heater (10) powered by liquid fuel and having a burner (14) and a reciprocating piston fuel pump (16), the reciprocating piston fuel pump (16) comprises an elastomer (36) And a damping member (34) for reducing pulsation generated by the reciprocating piston fuel pump (16), wherein the method preheats the elastomer before ignition of the burner (14). ) How to start up and work. The method of claim 6, The elastomer (36) is heated by an electric heating device (46). The method according to claim 6 or 7, The elastomer (36) is heated by a winding (22) of the reciprocating piston fuel pump (16) which is electromagnetically driven.

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