EP1260698B1 - Fuel supply system - Google Patents

Description

State of the art

The invention relates to a fuel supply system according to the preamble of claim 1.

A fuel supply system of an internal combustion engine, preferably in a motor vehicle, usually comprises a plurality of units. In the fuel supply system, a fuel pump delivers fuel from a fuel supply from a fuel tank via various units until the fuel finally enters a combustion chamber of the internal combustion engine. One of the units is for example a pressure regulator, a fuel accumulator, a pressure damper, a fuel filter or a fuel injection valve.

It may be that one of the units, for example, the pressure regulator, itself or a component of this unit, is electrically conductive, but the electrically conductive member or the unit is arranged electrically isolated, for example, characterized in that the unit on a non-conductive Plastic existing body is arranged.

The German patent application DE 44 02 224 A1 shows such a unit downstream of a fuel pump. Here, a pressure regulator is integrated into a plastic body. The pressure regulator has a housing made of sheet metal. This housing part is an electrically conductive component which has no electrically conductive connection to an electrical conductor forming a defined electrical potential.

Underlying technical problem

In the aggregate with an electrically conductive component can be carried out by electrical charge separation, an electrostatic charge of the electrically conductive component. Since the electrostatic charging of the electrically conductive component usually does not cause any problems, in particular no malfunction, the electrostatic charging of the electrically conductive component is normally unnoticed or at least ignored. Because there are aggregates through which the fuel flows through a narrow gap, for example at a high flow rate, for example in a pressure regulator, the electrostatic charge of the electrically conductive component can be very strong.

Sometimes, fortunately very rarely, it could happen that a fuel supply system caused a fire or an explosion with unexplained cause. The present inventors believe that at least a portion of these unexplained fires have been caused by electrostatic charging of an electrically isolated component of an aggregate of the fueling system.

EP-A-0 754 852 shows a tank pump assembly having a fuel pump and a fuel filter. In the tank pump assembly, a resilient mail piece is provided between the housing of the fuel pump and the housing of the fuel filter. The resilient pole piece bridges a gap between the fuel filter and the fuel pump. The resilient pole piece is attached to the housing of the fuel filter. To attach the pole piece, the fuel filter must be prepared accordingly, which is why the fuel filter must have a special housing. Depending on the distance between the fuel pump and the filter, the pole piece must be adjusted accordingly.

US 3,289,200 shows a housing for a control light. At the existing plastic housing two pins are integrally formed. On the pins electrical connectors are attached. Between the pins and the electrical connecting elements, the connecting wires of a control bulb are clamped.

Advantages of the invention

The fuel supply system according to the invention with the features of claim 1 has the advantage that an electrostatic charge of the electrically conductive member is prevented and any source of danger caused thereby is eliminated, being achieved with the clamping spring in a very simple manner that one with the electrical potential connecting electrical connection can be very safe and reliable connected to the electrically conductive component. Frequently, no change or redesign of the electrically conductive component is required.

The measures listed in the dependent claims advantageous refinements and improvements of claim 1 fuel supply system are possible.

drawing

Preferably selected, particularly advantageous embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. FIGS. 1 to 5 show different exemplary embodiments or differently executed details.

Description of the embodiments

The inventively designed fuel supply system is used for supplying fuel in an internal combustion engine. As an internal combustion engine, for example, a gasoline engine come into question. The fuel is, for example, gasoline or diesel, wherein, because gasoline is particularly easily flammable, it is proposed to carry out the fuel supply system according to the invention at least when the fuel is gasoline.

1 shows an exemplary selected fuel supply system.

1 shows a fuel tank 2. The fuel tank 2 has in its upper wall an opening 4. The opening 4 is closed with a plastic cover 6 existing. The lid 6 is screwed by means not shown screws on the upper wall of the fuel tank 2. In order to produce the cover 6 despite its non-simple design with reasonable effort and weight reasons, the cover 6 is made of plastic. In the lid 6, a pressure regulator 8 is functional and formal firmly integrated. The pressure regulator 8 has a housing 10. In the illustrated embodiment, the housing 10 consists of a first housing part 11 and a second housing part 12. In the housing 10, there is a membrane unit 14. In the illustrated embodiment, the membrane unit 14 comprises a membrane 15, a first plate 16, a second plate 17 and a closing body 18. The plates 16 and 17 are fixedly connected to the membrane 15 in the middle region of the membrane 15. At its outer periphery, the membrane 15 is installed between the first housing part 11 and the second housing part 12. The first plate 16 holds the closing body 18, which is for example a flattened ball. The membrane 15 consists of one or more, preferably two layers of flexible plastic plates.

The membrane 15 of the membrane unit 14 separates a first space 21 from a second space 22. The first space 21 is located substantially within the first housing portion 11, and the second space 22 is located substantially within the second housing portion 12. Within the lid. 6 There is a channel 24 and a return channel 26. In the illustrated embodiment, the channel 24 has an inlet side 24a and a secondary side 24b. The first housing part 11 has a bottom portion with a central recess 27 on the side offset the bottom portion of the housing part 11 has a passage 28. On the cover 6 a protruding through the central recess 27 nozzle is formed. At one of the closing body 18 of the membrane unit 14 facing the front end of the neck of the plastic cover 6, a valve seat 29 is provided. The return passage 26 extends through the lid 6 from the valve seat 29 in the fuel reservoir second

Because of the non-electrically conductive cover 6, the electrically conductive housing 10 of the pressure regulator 8 is electrically isolated from other conductive bodies representing a defined electrical potential. It may also be that the lid 6 is made of electrically conductive material, but for example by an electrically non-conductive intermediate plate, the lid 6 is electrically isolated from other electrically conductive components of the motor vehicle. This results in an electrically insulating body 30, which is formed in the illustrated embodiment in the form of the lid 6.

A provided in the interior of the fuel tank 2 fuel pump 32 sucks fuel from an existing in the fuel tank 2 fuel supply 34 and delivers the fuel through a pressure line 36 via the inlet side 24a in the channel 24. Through the channel 24 of the fuel passes to the secondary side 24b and then For example, to injectors, not shown in the figure 1. Through the passage 24, the fuel also passes through the passage 28 in the first space 21. If the pressure in the first space 21 is smaller than a certain opening pressure, then the closing body 18 abuts against the valve seat 29, and the first space 21 is opposite the return channel 26 completed. When the pressure in the first space 21 exceeds the predetermined opening pressure, the closing body 18 of the diaphragm unit 14 lifts from the valve seat 29, and excess fuel can escape from the passage 24, through the first space 21, through the gap between the valve seat 29 and the closing body 18 and then pass through the return passage 26 back into the fuel tank 2. A closing spring 38 acts on the plate 17 and thus the closing body 18 against the valve seat 29. Instead of the closing spring 38 or in addition to the closing spring 38, a prevailing in the second space 22 pressure to produce the serve the closing body 18 against the valve seat 29 acting on the closing force. In the illustrated embodiment, the housing part 12 for the purpose of pressure equalization frontally an opening 39th

If the fuel flows through the plastic cover 6 or electrically insulating body 30, then this can lead to a charge separation and thus to an electrostatic charge, for example, of the housing 10. The risk of charge separation and thus the electrostatic charge is increased because the fuel flows through the narrow gap between the valve seat 29 and the valve body 18 at high flow velocity from the first chamber 21 in the return passage 26. If the electrostatic charge of the housing 10 has reached a critical value, for example a few 1000 V (several thousand volts), then it can happen that an electrical flashover occurs in which the electrostatic charge is partially or completely degraded. Because the housing 10 is made of metal and thus is a good electrically conductive component, the charge built up on the entire housing 10 discharges in a concentrated manner in a short time, because the charge of the entire housing 10 flows in place of the flashover. As a result, the risk is not excluded that the electrical flashover reaches a size that leads to ignition of a fuel-air mixture. A certain ignitable mixture inside or outside of the fuel tank 2 in the area of the fuel supply system can not always be completely avoided.

In order to avoid the dangerous electrostatic charge of the electrically insulated in itself arranged housing 10, it is proposed that the housing 10 via an electrical Connection 40 with a defined electrical potential 41 to connect. For example, in the selected embodiment, the electrical conductor 44 represents the defined electrical potential 41.

The electrical conductor 44 is used to power the fuel pump 32. The fuel pump 32 is connected via the electrical conductor 44 and a second electrical conductor 44 'to a power supply, not shown. The electrical conductor 44 is for example a negative pole and the second electrical conductor 44 'is for example a positive pole. The electrical conductor 44 and thus the negative terminal is connected, for example, with the electrical ground of the motor vehicle, in which the fuel supply system is installed, for example. It is also possible that the electrical conductor 44 is the positive pole and the second electrical conductor 44 'is the negative pole. Depending on requirements, the positive pole or the negative pole can be connected to the electrical ground of the motor vehicle. To derive the electrostatic charge of the electrically conductive housing 10, this may in principle be connected to the negative pole 44 or to the positive pole 44 ', wherein it is not essential for the dissipation of the electrostatic charge, whether the electrical conductor 44 or the second electrical conductor 44th 'is connected to the electrical ground of the motor vehicle. However, it is proposed to connect the housing 10 via the electrical connection 40, preferably with the negative pole forming electrical conductor 44, wherein usually the negative terminal is connected to the electrical ground of the motor vehicle, so that the electrical mass of the motor vehicle, the defined electrical potential 41st ., to which the metal housing 10 is connected.

The electrical connection 40 comprises, for example, a simple, relatively thin, insulated strand or a flexible, thin, metallic wire 42 coated with insulating material. The electrical conductors 44 and 44 'open into a plug 46, which leads into a housing of the fuel pump 32 provided mating connector is inserted. Inside the plug 46, the wire 42 of the electrical connection 40 is electrically connected to the electrical conductor 44. The insertion of the wire 42 of the electrical connection 40 next to the conductors 44, 44 'in the plug 46, is easily possible without significant additional effort. The two electrical conductors 44, 44 'can also be replaced by a two-core cable, for example.

The electrical connection 40 is connected at a connection point via a connection 50 to the housing 10. The terminal connection 50 can be made, for example, by soldering or welding a stripped end of the wire 42 of the electrical connection 40 to the housing 10 or to a tab projecting on the housing 10. To facilitate the assembly of the fuel supply system, it is proposed to form the connection connection 50 so that the electrical connection 40 can be connected to the housing 10 of the pressure regulator 8. The following figures show details of differently designed connection connections 50.

FIG. 2 shows a non-inventive example.

In all figures, identical or equivalent parts are provided with the same reference numerals. Unless otherwise stated or illustrated in the drawing, that also applies with reference to one of the figures mentioned and illustrated in the other embodiments. Unless otherwise stated in the explanations, the details of the various embodiments can be combined with one another.

FIG. 2 shows by way of example the region of the connection connection 50 as a detail. 2 shows the second housing part 12 of the housing 10 of the pressure regulator 8. The housing part 12 is made of formed sheet metal.

In the exemplary embodiment illustrated in FIG. 2, a clamping spring 74 is attached to the end of the wire 42 facing the pressure regulator 8. The clamping spring 74 has an end into which the wire 42 is clamped. The wire 42 is clamped at this end, as is common in plugs in automotive engineering. The made of electrically conductive, resilient sheet clamping spring 74 is punched out of a thin, resilient sheet metal plate. The clamping spring 74 has an area forming a ring 74a. At the ring 74 a tabs 74 b are formed. Before attaching the clamping spring 74 on the housing part 12, the tabs 74b protrude radially inward. The tabs 74b protrude so far inward that after attaching the clamping spring 74 on the housing part 12, the tabs are bent approximately by 10 ° to 80 °. As a result, the clamping spring 74 hooks with the housing 10, so that a slight insertion of the clamping spring 74 is possible, but accidental slippage of the clamping spring 74 is prevented from the housing part 12 with certainty.

FIG. 3 shows a further exemplary embodiment according to the invention.

3 shows an embodiment with a clamping spring 74 ', wherein the clamping spring 74' (FIG. 3) is designed substantially the same as the clamping spring 74th (Figure 2). The tabs 74b of the clamp spring 74 'are approximately as wide and thick as to mate with the plug 54 attached to the wire 42. One of the tabs 74b of the clamping spring 74 'is slightly more outwardly bent, and the plug 54 is attached to this more bent tab 74b.

At the housing 10 facing the end of the wire 42, a plug 54 is attached. The plug 54 has a shape which is common as a simple-shaped plug in the automotive industry. The tab 74b is shaped so that the plug 54 can be plugged directly onto the tab 74b. The tab 74b is located in the region of the cylindrical jacket surface of the housing part 12 of the housing 10.

In the tab 74b, a hole is provided. The hole corresponds to a survey in the plug 54, so that slipping of the plug 54 is prevented by the tab 74b with certainty.

FIG. 4 shows another fuel supply system selected by way of example.

In the case of the fuel supply system shown in FIG. 1, the unit comprising the electrically conductive component forms the pressure regulator 8. In the exemplary embodiment shown in FIG. 4, the electrically insulating body 30, the housing 10, the membrane unit 14 and a stop 29 provided on the body 30 'the essential parts of a memory 8'. Depending on whether the memory 8 'relatively little or relatively little fuel absorbs or gives off pressure changes in the channel 24, the memory 8' is used only for smoothing sharp pressure pulsations in the channel 24, or the memory 8 'can with increasing pressure larger amounts of fuel record, which he then gives off at pressure drop, so that the memory 8 'as effective as a fuel tank can work. In the embodiment illustrated in FIG. 4, the valve seat 29 (FIG. 1) is omitted. For this, the membrane unit 14 comes into abutment against the stop 29 'provided on the body 30, and it is omitted. The return channel 26 shown in FIG.

In the embodiment shown in Figure 4, the electrical connection 40 is connected directly to the electrical ground 76, for example by connecting to the body of the motor vehicle. Here, the electrical ground 76 of the motor vehicle forms the defined electrical potential 41, to which the electrically conductive housing 10 of the memory 8 'is connected. Of course, the memory 8 'shown in FIG. 4, such as the pressure regulator 8 shown in FIG. 1, can also be connected to the conductor 44 or 44' leading to the fuel pump 32 (FIG. 1).

FIG. 5 shows a further, selected, particularly advantageous exemplary embodiment.

In the embodiment shown in Figure 5, a circumferential groove groove 62 is provided in the recess 58. In the groove grove 62, a snap ring 64 is inserted. The snap ring 64 holds a by radially flaring, circumferential bead formed by crimping the two housing parts 11, 12 on the housing 10 against a shoulder 66 of the recess 58 in the electrically insulating body 30th

In this embodiment, the pressure regulator 8 is not on the cover 6 (FIG. 1), but the pressure regulator 8 is attached to a fuel distribution pipe 78 made of plastic. On the continuing side 24b of the channel 24 leading through the fuel distributor tube 78 in this exemplary embodiment, an injection valve 80 is provided connected. Depending on the number of cylinders of the internal combustion engine, the fuel distributor tube 78 has a plurality of secondary sides 24b branching off from the channel 24, to each of which an injection valve is connected, wherein for better clarity, only one of the injection valves 80 is shown. All injectors can be the same design and connected the same.

In the housing part 82 there is a bore 84 through which, controlled by a valve body 86, fuel from the channel 24 of the Kraftstoffverteilrohrs 78 in an existing example of plastic, not shown suction pipe of the internal combustion engine can flow with high flow velocity.

In this embodiment, the existing plastic fuel distribution pipe 78 forms the electrically insulating body 30. Also on the suction pipe, an electrostatic charge of the injection valve 80 can not be prevented if the suction pipe, as is common, made of electrically non-conductive material, eg. As plastic.

Due to the high flow rate of the fuel between the housing part 82 and the valve body 86, a charge separation may occur, which can lead to an electrostatic charge of the housing part 82 when the housing part 82 is not connected to a defined electrical potential. In order to prevent the electrostatic charge of the housing part 82, the housing part 82 is connected via an electrical connection 40 'to the defined electrical potential 41. The wire 42 'of the electrical connection 40' is For example, connected to a wire of a cable 88, via which the injection valve 80 is electrically connected to a control unit, not shown. In this embodiment, one of the wires in the cable 88 defines the defined electrical potential 41. Also connected to the same electrically conductive wire of the cable 88 to which the wire 42 'of the electrical connection 40' is connected is the wire 42 of the electrical connection 40 be connected. Which of the wires is used in the defined electric potential cable 88 does not matter in principle. The cable 88 is connected via a plug 90 to the injection valve 80. It requires no significant additional effort, along with the cable 88 and the wires 42 and 42 'to connect to the plug 90. In addition, there is the advantage that a short overall length is sufficient for the wires 42 and 42 ', because the plug 90 is located in the region of the components to be protected from electrostatic charge.

The wire 42 'of the electrical connection 40' is connected via a connection connection 50 'to the electrically conductive housing part 82 of the injection valve 80. The connection connection 50 'can be designed the same, as shown with respect to the connection connection 50.anhand of several figures.

The pressure regulator 8 (Figure 1, 5), the memory 8 '(Figure 4), the injection valve 80 (Figure 5) and optionally other components of the fuel supply system, such as a fuel filter, are units of the fuel supply system, an electrically conductive component or have a plurality of electrically conductive components, such as the housing parts 11, 12 (Figure 1, 4, 5) or the housing part 82 (Figure 5), because of the electrically insulating body 30, for example, the lid. 6 (Figure 1, 4) or the Kraftstoffverteilrohr 78 (Figure 5) or other of non-conductive material existing electrically insulating body, opposite an electrical conductor, which could represent the defined electrical potential 41, are electrically isolated.

The pressure regulator 8 and the memory 8 'are hydraulically operating units that do not require any electrical connection. The electrical connection 40 serves only to connect the component of the pressure regulator 8 or the accumulator 8 'made of electrically conductive material with the defined electrical potential 41.

Claims (5)

1. Fuel supply system having a fuel pump which feeds fuel from a fuel supply via an assembly (8, 8', 80), the assembly (8, 8', 80) comprising at least one electrically conductive component (10, 11, 12, 82) which is secured in an electrically insulating arrangement (6, 30, 78), the electrically insulating arrangement (6, 30, 78) disconnecting the electrically conductive component (10, 11, 12, 82) from an electrical potential of an electrical conductor, and the electrically conductive component (10, 11, 12, 82) being connected via an electrical line (40, 40', 42, 42') to the electrical potential (41) of the electrical conductor (44, 44', 76, 88), characterized in that a clamping spring (74, 74') is provided, and the clamping spring (74, 74') has a ring (74a) on which clips (74b) which point radially inwards are provided, the clips (74b) projecting so far inwards that after plugging onto the component (10, 11, 12, 82) the clips (74b) are bent over, as a result of which the clamping spring (74, 74') is interlocked with the component (10, 11, 12, 82) and the electrical connection is formed between the clips (74b) and the component (10, 11, 12, 82) which holds the clamping spring (74, 74'), and in that the electrical connection (40, 40', 42, 42') is connected to the clamping spring (74, 74') via a plug-type connection to a plug (54), a clip (74b) which protrudes from the component (10, 11, 12, 82) being provided on the ring (74a), and the clip (74b) is shaped in such a way that the plug (54) can be plugged onto the clip (74b) which protrudes from the component (10, 11, 12, 82).
2. Fuel supply system according to Claim 1, characterized in that the component (10, 11, 12, 82) is a housing part (10, 11, 12, 82) of the assembly (8, 8', 80).
3. Fuel supply system according to Claim 1 or 2, characterized in that the component (10, 11, 12) is part of a pressure regulator (8).
4. Fuel supply system according to Claim 1 or 2, characterized in that the component (10, 11, 12) is part of an accumulator (8').
5. Fuel supply system according to Claim 1 or 2, characterized in that the component (82) is part of an injection valve (80).

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