FUEL PUMP AND FUEL DELIVERY UNIT

Description

[0001] The invention relates to a fuel pump and a fuel delivery unit comprising such a fuel pump for use in a fuel tank of a vehicle for delivering fuel to an internal combustion engine. A vehicle is understood to mean any type of vehicle that requires a liquid and / or gaseous fuel for operation, but in particular passenger cars and / or commercial vehicles.

[0002] Such a fuel pump and fuel delivery unit are widely known from the prior art. The fuel pump comprises a pump stage and an electric motor that drives the pump stage. The electric motor and pump stage are rolled together in a sheet metal casing or cylinder, which essentially encapsulates both the electric motor and the pump stage, thereby sealing them.

[0003] In automotive engineering, electrically conductive or antistatic plastic fuel lines have long been used in series production to dissipate static charges generated during fuel delivery to ground potential. These prevent static charging at high flow rates, which in the worst case can lead to flying sparks and spontaneous combustion of a vehicle. To be electrically conductive, these plastic lines are either made entirely of an electrically conductive plastic or are coated with at least one electrically conductive layer so that the static charge can be dissipated to ground potential.

[0004] The document DE 10 2008 004845 A1 discloses a fluid pump with an electric motor housing made of sheet metal and a pump housing for accommodating a pump stage, wherein the pump housing is made of a plastic.

[0005] The document WO 00 / 60231 A1 discloses a fuel pump with an electric motor housing made of sheet metal and a pump housing for accommodating a pump stage, wherein the pump housing is made of an electrically conductive plastic.

[0006] EP 0 754 483 A1 discloses a fuel filter holder comprising a fuel filter and a fuel pump arranged in the fuel filter holder, which is driven by an electric motor. The electric motor has a metal housing, which interacts with a lower part of the fuel filter holder, which is made of a conductive plastic, to dissipate an electrical charge.

[0007] One object underlying the invention is to improve such a dissipation of static charges to a ground potential.

[0008] This object is achieved by claim 1, which protects a fuel pump. Advantageous embodiments of the invention are the subject of the dependent claims.

[0009] A fuel pump is proposed, comprising an electric motor, a pump stage driven by the electric motor and a fuel pump housing accommodating the electric motor and the pump stage.

[0010] It is proposed that the fuel pump housing has a first housing part for accommodating the electric motor and a second housing part for accommodating the pump stage, wherein the first housing part is made of a conductive plastic for discharging static charges to a ground potential.

[0011] Such a plastic-conductive design of the first housing part supports the use of electrically conductive or antistatic fuel lines made of plastic, as described above and known from the state of the art.

[0012] An embodiment of the invention is characterized in that the second housing part is made of a conductive plastic for discharging static charges to a ground potential.

[0013] Such a plastic-conductive design of the first housing part and the second housing part supports the use of electrically conductive or antistatic fuel lines made of plastic, as described above and known from the prior art.

[0014] According to a further aspect of the present invention, the plastic used for the plastics-technical production of the first housing part and / or the second housing part can be provided with graphite powder, which ensures the conductivity of the plastic.

[0015] According to a further aspect of the present invention, the plastic used for the plastics-technical production of the first housing part and / or the second housing part can additionally or alternatively be provided with carbon fibers, which ensures the conductivity of the plastic.

[0016] According to a further aspect of the present invention, the plastic used for the plastics-technical production of the first housing part and / or the second housing part can additionally or alternatively be provided with metal fibers, which ensures the conductivity of the plastic.

[0017] Furthermore, a fuel delivery unit with a fuel pump of the type described above is proposed.

[0018] The invention will be explained in detail below with reference to the figures. Further advantageous developments of the invention will become apparent from the dependent claims and the following description of preferred embodiments. These are shown in: Fig.1 a plan view of a proposed fuel pump, Fig.2 a first side view of the Fig.1 shown fuel pump and Fig.3 a second side view of the Fig.1 shown fuel pump

[0019] A fuel pump 2 is proposed, comprising an electric motor 4, a pump stage 6 driven by the electric motor 4, for example in the form of a screw pump stage, and a fuel pump housing 8, 9, 10 accommodating the electric motor 4 and the screw pump stage 6. The fuel pump housing 8, 9, 10 comprises a first housing part 10 made of plastic with a receptacle 16 in which the electric motor 4 is arranged, and a second housing part 8 made of plastic, which accommodates the screw pump stage 6. The screw pump stage 6 comprises a pump housing 9, which is joined to a pump cover 8. The pump cover 8 forms the second housing part described above.

[0020] The pump cover 8 is joined to a corresponding section 10 F of the housing part 10, which protrudes in the axial direction X - X of the fuel pump 2, via a section 8 F projecting circumferentially in the axial direction X - X. At the joint, the pump cover 8 is also integrally connected to the housing part 10. The integral connection can be embodied as an adhesive and / or welded joint. This connection acts as a seal with respect to the pumped fuel.

[0021] On the pressure side D of the pump housing 9, a stepped section 9A is formed, which acts as a stop. This section is provided with a flat stop surface and abuts against an associated flat stop section 10A of the housing part 10. The pump cover 8, in turn, abuts flatly against the stop section 9A with its pressure-side end, which is provided with a flat stop surface.

[0022] Between the pump housing 9 and the pump cover 8, a radial seal in the form of an O-ring is arranged, which on the one hand acts as a seal with respect to the pumped fuel and on the other hand centers the pump cover 8 in a floating manner relative to the pump housing 9.

[0023] Alternatively, a design of a screw pump stage that does not require such a pump cover is also conceivable. In such a coverless screw pump stage, the pump housing 9 forms the second housing part 8, which is joined and materially connected to the first housing part 10.

[0024] Two counter-rotating screw spindles 18, 20 arranged in the pump housing 9 form, together with the pump housing 9, delivery chambers 22, which move from a suction side S to a pressure side D of the pump stage 6 as a result of a rotation of the screw spindles 18, 20. Or, to put it another way, the delivery chambers 22 move in the direction of the pressure side D as a result of a rotation of the screw spindles 18, 20.

[0025] A pump housing section 24, which has a centering effect relative to the first housing part 10, projects into the receptacle 16 to join the pump housing 9 to the housing part 10 and thereby provides a bearing point 26 for the rotor 12 of the electric motor 4, into which the associated shaft end of the rotor 12 extends. This shaft end engages, for connection to the screw spindle 18 acting as the drive spindle, via a projecting section in a coupling 29, which as such sits positively on the drive spindle 18. The other bearing point 27, however, into which the other shaft end of the rotor 12 extends, is provided by the housing part 10 itself. The bearing point 27 is formed onto the receptacle 16 at a cover-side end of the housing part 10. This means that the bearing point 27 is formed during the plastics production of the housing part 10.

[0026] The pump housing 9 is circumferentially aligned with the housing part 10. For this purpose, a rib section (not shown in the figures) is formed on the pressure side of the pump housing 9 in the radial direction and is inserted into a corresponding recess in the housing part 10.

[0027] Furthermore, permanent magnets 14 are arranged buried in the housing part 10 and distributed over the circumference, which interact with a laminated core of the rotor 12, which carries the windings and forms the poles and is also referred to as the armature core.

[0028] A third plastic housing part 11 is also provided, which functions as a cover. This plastic housing part is joined to the housing part 10 at a joint 13 and is integrally connected. This connection also acts as a seal with respect to the pumped fuel. This integral connection can also be formed as an adhesive and / or welded joint. Alternatively, such a cover 11 can also be omitted. If the cover 11 were omitted, the corresponding closing section of the housing part 10 would be formed during the plastics-based production of the housing part 10.

[0029] Both a connecting piece 28 for connecting to a fuel line and a connecting socket 30 for electrically connecting the electric motor 4 are led away from the housing part 10 transversely - and in this exemplary embodiment orthogonally - to a longitudinal direction X - X of the fuel pump 2. The connecting socket 30 comprises a section 32 formed on the housing part 10 with contacts 33 which are connected to lines 34, wherein the lines 34 lead away transversely or orthogonally to the longitudinal direction X - X. Such orthogonality is to be understood only as an example and is not absolutely necessary, because even a routing of the connecting piece 20 and the connecting socket 18 from the housing part 10 in the transverse direction that deviates from a right angle to the longitudinal direction X - X contributes to saving installation space in the longitudinal direction X - X.

[0030] The arrangement of the pump housing 9 to the housing part 10 is such that the pump housing 9 and the housing part 10 form a fuel channel KK opening into the connection piece 28, which functions as a hydraulic outlet. This fuel channel KK is in flow connection or fluidic communication not only with the connection piece 28, but also with the receptacle 16, in which the rotor 12 is arranged, in order to enable flow around the rotor 12 for cooling purposes. This means that the fuel channel KK guides the pumped fuel both transversely to the longitudinal direction X - X of the fuel pump 2 into the connection piece 28 and in the longitudinal direction X - X of the fuel pump 2 into the receptacle 16.

[0031] To dissipate static charges resulting from fuel delivery to a ground potential, it is proposed to construct the housing part 10 and / or the housing parts 8, 9 from a conductive plastic. Such a conductive plastic could, for example, be provided with graphite powder, carbon fibers, and / or metal fibers to ensure the conductivity of the plastic.

[0032] Such a plastic-conductive design of the housing part 10 and / or the housing part 8, 9 supports the use of electrically conductive or antistatic fuel lines made of plastic, which is known from the prior art.

[0033] The delivery of fuel by the fuel pump 2, which as such is also referred to as a fuel delivery unit, is as follows: The fuel pump 2 sucks the fuel into the delivery chambers 22 via an inlet opening 2E on the suction side on the pump cover 8, via which the fuel is then delivered to at least one outlet opening on the pressure side of the pump housing section 24, through which it then flows both into the receptacle 16 for flow around the rotor 12 and into the flow channel KK and then on to the outlet nozzle 28, via whose outlet opening 2A it finally exits the fuel pump or the fuel delivery unit 2. The said at least one pressure-side outlet opening of the pump housing section 24 is therefore in flow connection or fluidic communication connection to both the fuel channel KK and the receptacle 16.

[0034] Although exemplary embodiments have been explained in the foregoing description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the foregoing description provides the skilled person with a guide for implementing at least one exemplary embodiment, whereby various modifications, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as defined by the claims.

Claims

1. Fuel pump comprising an electric motor (4), a pump stage (6), which is able to be driven by the electric motor (4), and a fuel-pump housing (8, 9, 10), which accommodates the electric motor (4) and the pump stage (6), wherein the fuel-pump housing (8, 9, 10) has a first housing part (10) for accommodating the electric motor (4) and has a second housing part (8, 9) for accommodating the pump stage (6), characterized in that the first housing part (10) is formed from a conductive plastic for dissipating static charges to an earth potential.

2. Fuel pump according to Claim 1, characterized in that the second housing part (8, 9) is formed from a conductive plastic for dissipating static charges to an earth potential.

3. Fuel pump according to Claim 1 or 2, characterized in that the plastic is provided with graphite powder, which ensures the conductivity of the plastic.

4. Fuel pump according to one of the preceding claims, characterized in that the plastic is provided with carbon fibres, which ensure the conductivity of the plastic.

5. Fuel pump according to one of the preceding claims, characterized in that the plastic is provided with metal fibres, which ensure the conductivity of the plastic.

6. Fuel-delivery unit having a fuel pump (2) according to one of Claims 1 to 5.