EP3234343B1 - Piston fuel pump for an internal combustion engine - Google Patents

Piston fuel pump for an internal combustion engine Download PDF

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Publication number
EP3234343B1
EP3234343B1 EP15805167.2A EP15805167A EP3234343B1 EP 3234343 B1 EP3234343 B1 EP 3234343B1 EP 15805167 A EP15805167 A EP 15805167A EP 3234343 B1 EP3234343 B1 EP 3234343B1
Authority
EP
European Patent Office
Prior art keywords
pump
piston
seal
working chamber
end section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
EP15805167.2A
Other languages
German (de)
French (fr)
Other versions
EP3234343A1 (en
Inventor
Jochen Kaesser
Bernd Beiermeister
Soeren Stritzel
Wolfgang Ochs
Ralf Assmann
Heiko Jahn
Christian Preissner
Achim LAUB
Peter Ropertz
Stefan ZAENSCH
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
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Publication of EP3234343A1 publication Critical patent/EP3234343A1/en
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Publication of EP3234343B1 publication Critical patent/EP3234343B1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
    • F02M59/44—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston
    • F02M59/442—Details, components parts, or accessories not provided for in, or of interest apart from, the apparatus of groups F02M59/02 - F02M59/42; Pumps having transducers, e.g. to measure displacement of pump rack or piston means preventing fuel leakage around pump plunger, e.g. fluid barriers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
    • F04B1/0404—Details or component parts
    • F04B1/0408—Pistons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/04—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinders in star- or fan-arrangement
    • F04B1/0404—Details or component parts
    • F04B1/0448—Sealing means, e.g. for shafts or housings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/14—Pistons, piston-rods or piston-rod connections
    • F04B53/143—Sealing provided on the piston
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/80—Fuel injection apparatus manufacture, repair or assembly
    • F02M2200/8046—Fuel injection apparatus manufacture, repair or assembly the manufacture involving injection moulding, e.g. of plastic or metal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
    • F02M2200/80—Fuel injection apparatus manufacture, repair or assembly
    • F02M2200/8061—Fuel injection apparatus manufacture, repair or assembly involving press-fit, i.e. interference or friction fit

Definitions

  • the invention relates to a piston fuel pump according to the preamble of claim 1.
  • piston fuel pump comprises a pump cylinder and a pump piston slidably received in the pump cylinder.
  • This piston fuel pump has a mounting and sealing arrangement for the pump piston, which comprises a guide area for axially guiding the pump piston in the pump cylinder and a sealing area having a sealing lip.
  • DE102013226062 A1 discloses another piston fuel pump.
  • a piston fuel pump according to claim 1 is provided.
  • the seal seals a gap between the pump piston and the pump cylinder.
  • direct application is understood in particular to mean that the material of the seal is applied to the piston in a liquid state and then solidifies on the piston, in particular solidifies as a result of cooling.
  • the direct application of the seal to the pump piston by means of an injection molding process has the advantage, on the one hand, that a separate production of the seal and subsequent handling and connection to the pump piston are not required, and production is thus simplified. Furthermore, diverse geometric configurations of the interface between the seal and the pump piston, in particular form-fitting connections, can easily be implemented in this way.
  • seal also seals off the end section of the pump piston on the working space side from the working space, in particular completely sealing it off.
  • the entire pump piston is located on the side of the seal facing away from the working chamber, that is to say in particular in a low-pressure region. In this way, leakage between the working space and the low-pressure area, which can occur in the pump known from the prior art along a path running between the pump piston and seal, is completely and reliably excluded.
  • the end section of the pump piston on the working chamber side is understood in particular to be a region which comprises the end face of the pump piston on the working chamber side and also an end portion of the pump piston pointing in the axial direction towards the working chamber.
  • the end section on the working space side can in particular be the tapered part of the stepped piston and / or the area of the pump piston on the working space side of the step.
  • the end section of the pump piston on the working chamber side can, for example, be formed only in the working chamber-side half of the pump piston in relation to the longitudinal extension of the pump piston, i.e. in the axial direction, or even only in the working chamber-side outer quarter of the pump piston in the axial direction.
  • the sealing of the working chamber-side end section of the pump piston against the working chamber by the seal can be realized in that the seal has a recess with an especially cylindrical basic shape, in which the working chamber-side end section of the pump piston is arranged and / or which is filled by the working chamber-side end section of the pump piston , in particular is filled in completely.
  • the seal covers, in particular, the end section of the pump piston on the working space side, both radially and on the end face of the pump piston facing the working space.
  • the seal has, in particular, a cup-shaped inner contour in which the end section of the pump piston on the working chamber side is arranged and / or which is filled, in particular completely filled, by the end portion of the pump piston on the working chamber side.
  • cup-shaped here implies in particular the presence of an end-face base, which can be designed as a round surface, for example, and a wall formed around the edge of the base, which can in particular extend perpendicular to the base.
  • cylindrical basic shape in particular also actually includes geometrically exact cylindrical shapes, but is basically to be understood broadly, in particular in the sense of “elongated” and does not represent any restriction with regard to surface structures that can be formed on the pump piston and on the seal and which will be discussed in more detail below.
  • the end section of the pump piston on the working space side and the seal can be connected to one another in a force-locking manner, In particular, the seal can rest under tension on the end section of the pump piston on the working space side.
  • the end section of the pump piston on the working space side has a first surface structure and the seal has a second surface structure and the first surface structure and the second surface structure are complementary to one another and / or engage in one another.
  • the first surface structure and the second surface structure can fill one another, in particular fill them completely.
  • a surface structure of the seal or the pump piston is understood to mean in particular geometric features that do not relate to the basic geometric shape of the seal or the pump piston already discussed above.
  • surface structures can only have features whose structure sizes are significantly smaller, for example not greater than 10%, than structure sizes of the seal and / or the end section of the pump piston on the working space side, for example the total length and / or the widest diameter of the seal and / or the pump piston and / or the end section of the pump piston on the working chamber side.
  • the surface structure of the seal is either a grooved structure and / or a wave structure, in particular with grooves and / or waves that run radially around the end section of the pump piston on the working space side, or a knurled structure, in particular a cross-knurled structure, which is simple and easy on a pump piston Way can be applied.
  • the term knurled structure is understood in particular with reference to DIN 82 from 1973. Structure sizes of geometrically regular surface structures in the axial and / or tangential direction are given in particular by their periodicity. Structure sizes of geometrically regular surface structures in the radial direction are given in particular by their amplitude.
  • surface structures with structure sizes in the radial direction in the range from 0.1 mm to 2 mm are advantageously possible.
  • Deep structures for example with structure sizes in the radial direction of 0.5 mm or more, have the advantage of being particularly effective Toothing between the end section of the pump piston on the working chamber side and the seal.
  • flat structures for example with structure sizes in the radial direction of 0.5 mm or less, have the advantage that they are particularly easy to manufacture.
  • the structure size in the radial direction ie the structure depth
  • the structure size in the axial and / or tangential direction is sufficiently large in comparison to the structure size in the axial and / or tangential direction, since this ensures the effect of a toothing.
  • the seal can in particular have a thermoplastic material or consist of a thermoplastic material.
  • the thermoplastic material can in particular be a thermoplastic polymer, for example a fiber-reinforced thermoplastic polymer. It can be, for example, polyetheretherketone (PEEK) reinforced with carbon fiber. One such is, for example, PEEK 150CA30. Another preferred thermoplastic material is PA66CF20.
  • the seal has a thickness in the range from 0.5mm to 1.8mm to ensure high strength, low mass and easy manufacture.
  • the fuel piston pump is, in particular, a pump that has a pump housing in which a working space delimited by the pump piston is formed.
  • the compression of the fuel takes place in particular in this working space, in particular by an axial movement of the pump piston that reduces the working space.
  • the fuel in the working chamber is compressed to a high pressure level, for example to 100 bar to 600 bar.
  • the seal according to the invention is formed in particular between the working space and a low-pressure area of the pump.
  • the pressure in the low pressure area is lower than the high pressure level that is generated in the working area of the pump.
  • the pressure level in the low pressure range can be, for example, 3 to 10 bar and can be generated by a separate backing pump.
  • the working space is connected in particular to a pump outlet via an outlet valve and in particular connected to a pump inlet via an electrically controllable inlet valve.
  • the electrically controllable inlet valve can in particular be designed as a quantity control valve.
  • a damping device for damping pulsations in the low-pressure region of the pump can also be provided between the pump inlet and the working chamber.
  • the damping device for damping pulsations in the low-pressure range can, for example, comprise a gas volume enclosed between two membranes; details regarding the damping device can be as in FIG DE10327408A1 be formed shown.
  • Another valve arranged between the pump outlet and the working chamber, which is arranged antiparallel to the outlet valve, can be provided and in particular act as a pressure limiting valve for a high-pressure accumulator that can be connected to the pump.
  • the outlet valve and / or the inlet valve and / or the pressure limiting valve are preferably fixed in a fixed position to the pump housing and, to this extent, also fixed in a fixed position to the pump cylinder. A fixation of these components on the pump piston is excluded in particular. There is the advantage that the mass of the pump piston is low and thus the dynamics or ease of movement of the pump is improved.
  • the pump piston is preferably designed as a solid body so that it can withstand the high pressures that act during fuel injection, in particular during gasoline direct injection, without deformation.
  • a permeability of the pump piston in the longitudinal direction is ruled out in this respect.
  • FIG DE102004013307A1 Further details of the arrangement of the working chamber, outlet valve and pressure relief valve to one another and in the pump body can be, for example, as in FIG DE102004013307A1 be formed shown.
  • the pump cylinder can be formed in a bushing fixed in the pump body. Alternatively, the pump cylinder can also be provided directly in the pump body.
  • the pump body, the pump piston, the pump cylinder and / or all pump parts that come into contact with the fuel are preferably only made of steel and plastic, so that the result is high resistance to fuels containing ethanol and / or other aggressive fuels .
  • the friction phenomena that occur can be divided into classes or phases according to DIN 50281, depending on the type of contact conditions between the friction partners, here the seal and the pump cylinder.
  • the friction partners are separated from one another by a liquid medium, for example by a continuous liquid film, in the present case for example by a continuous fuel film.
  • the frictional forces that occur are usually considerably lower than with solid body friction. The wear that occurs on the friction partners is correspondingly reduced.
  • mixed friction can also occur which, temporally and / or spatially, has proportions of solid body friction and proportions of liquid friction.
  • a radially outer surface of the seal which lies opposite an inner surface of the pump cylinder, is designed in an axial end region of the seal in such a way that it rests against the pump cylinder when the pump piston is stationary relative to the pump cylinder and that a relative movement between the pump cylinder and the pump piston in the axial direction favors a lifting of the seal from the pump piston in a radially inward direction.
  • a radially outer surface of the seal which is opposite an inner surface of the pump cylinder, is inclined radially inward in an axial end region of the seal at an angle of 10 ° to 60 ° to the inner wall of the pump cylinder.
  • the fuel to be compressed by the pump piston exerts, in particular, a radially inward force on the radially outer surface of the seal, so that it can in particular lift slightly from the pump cylinder and a fuel film can in particular form between the seal and the pump cylinder.
  • a fuel system of an internal combustion engine contributes to Figure 1 generally the reference numeral 10. It comprises a fuel tank 12, from which an electrical prefeed pump 14 conveys the fuel into a low-pressure line 16. This leads to a high pressure pump in the form of a piston fuel pump 18. From this a high pressure line 20 leads to a fuel rail 22. A plurality of injectors 24 are connected to this, which inject the fuel directly into combustion chambers (not shown) assigned to them.
  • the piston fuel pump 18 comprises a pump housing 26, only partially indicated, in which a pump piston 28 is displaceably guided or mounted. This can be set in a back and forth movement by a cam drive (not shown), which is indicated by a double arrow 30 drawn on the side.
  • the pump piston 28 is converted into an in Figure 1 applied to lower dead center.
  • the pump piston 28 and the pump housing 26 delimit a working space 34.
  • This working space 34 can be connected to the low-pressure line 16 via an inlet valve 36.
  • the working chamber 34 can be connected to the high-pressure line 20 via an outlet valve 38.
  • Both the inlet valve 36 and the outlet valve 38 are designed as check valves.
  • An embodiment of the inlet valve 36 as a quantity control valve is not shown, but possible.
  • the inlet valve 36 can be forcibly opened during a delivery stroke of the pump piston 28, so that the fuel is not delivered into the fuel rail 22, but back into the low-pressure line 16. In this way, the amount of fuel delivered by the piston fuel pump 18 into the fuel rail 22 can be adjusted.
  • the pump piston 28 is guided in a pump cylinder 40, which in this respect is part of the pump housing 26.
  • the pump piston 28 has an end facing the working chamber 34 in Figure 1 end portion 42 arranged above. In the vicinity of this end section 42 on the working space side, the pump piston 28 furthermore has an annular shoulder 44 in the manner of a radially protruding circumferential collar.
  • a seal 46 comes to rest on the pump piston 28 or on the shoulder 44 and surrounds the end section 42 of the pump piston 28 on the working space side axially and radially.
  • the end section 42 of the pump piston 28 on the work space side is completely sealed off from the work space 34, i.e. a medium located in the work space does not come into contact with the end section 42 of the pump piston 28 on the work space side and a hydraulic pressure effective in the work space thus acts on the end section 42 of the work space Pump piston 28 no longer or only indirectly via seal 46.
  • the pump piston 28 also has an in Figure 1 lower end portion 52.
  • a guide sleeve 54 is fixedly arranged on the pump housing 26.
  • An O-ring seal 56 is provided in a groove 58 between the guide sleeve 54 and the pump housing 26.
  • the guide sleeve 54 has a cylinder section 60 which extends coaxially to the pump piston 28 and through which the helical spring 32 is guided.
  • the helical spring 32 dips along a piston longitudinal axis 62, at least in sections, into a spring receiving groove 64 of the guide sleeve 54, where it is axially supported against the guide sleeve 54.
  • the guide sleeve 54 also has in the interior a circular cylindrical receiving section 66 which extends essentially through the inner peripheral wall of the cylinder portion 60 is formed.
  • an annular sealing element 68 is arranged in a stationary manner relative to the pump housing 26, the sealing element 68 having an H-shaped cross section.
  • a guide element 72 is also arranged in a stationary manner relative to the pump housing 26. This guide element 72, which is clearly spaced apart from the seal 46 in the axial direction of the pump piston 28, together provides the seal 46 with the guidance or two-point mounting of the pump piston 28.
  • Figure 2 shows a sectional view of a detail of the piston fuel pump 18, the working chamber-side end section 42 of the pump piston 28 and the seal 46 being shown enlarged.
  • the seal 46 has a recess 74 with a cylindrical shape, which is completely filled by the end section 42 of the pump piston 28 on the work space side, so that in cooperation with the sealing function existing between the seal 46 and the pump cylinder 40, the end section 42 of the pump piston 28 on the work space side completely against the work space 34 is sealed.
  • the seal 46 covers an end face 421 of the end section 42 of the pump piston 28 on the work space side and, in direct molding, a jacket surface 422 of the end section 42 of the pump piston 28 on the work space side, so that the end section 42 of the pump piston 28 on the work space side is completely covered by the seal 46.
  • a sealing lip 50 is provided radially on the outside of the seal 46 and cooperates in a sealing manner with the pump cylinder 40.
  • the seal 46 consists of the fiber-reinforced thermoplastic polymer PEEK 150CA30 or PA66CF20.
  • the seal 46 is produced by an injection molding process, in which the liquefied thermoplastic polymer in the axial injection direction, along the Piston longitudinal axis 62, is applied directly to the end section 42 of the pump piston 28 on the working chamber side.
  • a hot runner tool can be used for this, in which the melted thermoplastic polymer is introduced at a relatively high temperature into a cavity formed between the end section 42 of the pump piston 28 on the working space side and an injection mold.
  • the pump piston 28 with the seal 46 attached to it can be removed from the injection mold.
  • the seal 46 has a thickness d of one millimeter in order to ensure high strength, low mass and simple manufacture at the same time.
  • the end section 42 of the pump piston 28 on the working space side and the inner contour of the seal 46 have circumferential grooves.
  • the grooves have a depth t of 0.5 mm and a periodicity in the axial direction x of 1 mm. It can be a large number of grooves, each of which runs around in a closed manner.
  • the circumferential grooves can, however, also represent a single or multiple thread in their entirety.
  • the groove structure on the surface of the end section 42 of the pump piston 28 on the working space side is clearly complementary on the inner contour of the seal 46, that is, as a negative image, which in the present case results naturally in injection molding.
  • the grooves have a depth t of only 0.1 mm and a periodicity in the axial direction x of 1 mm.
  • the grooves have a depth t of 2 mm and a periodicity in the axial direction x of 9 mm. These grooves can also be designed as waves, see Figure 3c .
  • FIG Figures 3d and 3e Examples of end sections 42 of the pump piston 28 on the working space side with relatively large grooves which are further spaced apart are shown in FIG Figures 3d and 3e shown.
  • knurled structures or a cross-knurled structure can also be provided on the end section 42 of the pump piston 28 on the working space side and on the inner contour of the seal 46.
  • An example of such an end section 42 of a pump piston 28 on the working space side is shown in FIG Figure 3f shown.
  • irregular surface structures can of course also be provided on the end section 42 of the pump piston 28 on the working space side and on the inner contour of the seal 46, which in particular represent a roughness of the pump piston 28 and the seal 46.
  • the Pt value of a measurement of the surface of the pump piston is 0.2 mm and the wavelength at which the maximum of a spectral decomposition of the surface roughness (Ra spectrum) occurs is 1 mm.
  • An axial end region 464 of the seal 46 is formed in the present case on the working space side on the sealing lip 50. It is provided that a radially outer surface of the seal 46, which is opposite an inner surface of the pump cylinder 40, is inclined radially inward in an axial end region 464 of the seal 46 at an angle ⁇ of 10 ° to 60 ° to the inner wall of the pump cylinder 40 . This has the effect or alternatively it is provided that a relative movement between pump cylinder 40 and pump piston 28 in an axial direction Direction, in particular in the direction of the working chamber 34, favors a lifting of the seal 46 from the pump cylinder 28 in a radially inwardly pointing direction. In this case, a liquid film consisting of fuel is formed between the seal 46 and the pump cylinder 40, which, in the event of a slight leak, considerably reduces the wear on the piston fuel pump 18.
  • an outwardly facing, circumferential web 468 is integrally formed on or on the sealing lip 50, which has the shape of an isosceles triangle in cross section in the longitudinal direction, of which the two opposite pointed corners point in axial directions and the third is obtuse Corner on the pump cylinder 40 (static) rests. It is provided that only this web (statically) comes into contact with the pump cylinder 40, while the seal 46 or the sealing lip 50 is otherwise spaced apart from the pump cylinder 40 by a gap 77. A width s of the gap 77 is 20 ⁇ m, for example. In the event of a relative movement, as described above, a lifting of the web 468 from the pump cylinder 40 is also provided.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Details Of Reciprocating Pumps (AREA)
  • Fuel-Injection Apparatus (AREA)

Description

Stand der TechnikState of the art

Die Erfindung betrifft eine Kolben-Kraftstoffpumpe nach dem Oberbegriff des Anspruchs 1.The invention relates to a piston fuel pump according to the preamble of claim 1.

Beispielsweise die aus der WO 2014095120 A1 bekannte Kolben-Kraftstoffpumpe umfasst einen Pumpenzylinder und einen im Pumpenzylinder verschiebbar aufgenommenen Pumpenkolben. Diese Kolben-Kraftstoffpumpe weist eine Lagerungs- und Dichtanordnung für den Pumpenkolben auf, die einen Führungsbereich zur axialen Führung des Pumpenkolbens im Pumpenzylinder und einen eine Dichtlippe aufweisenden Abdichtbereich umfasst.For example, from the WO 2014095120 A1 known piston fuel pump comprises a pump cylinder and a pump piston slidably received in the pump cylinder. This piston fuel pump has a mounting and sealing arrangement for the pump piston, which comprises a guide area for axially guiding the pump piston in the pump cylinder and a sealing area having a sealing lip.

DE102013226062 A1 offenbart eine weitere Kolben-Kraftstoffpumpe. DE102013226062 A1 discloses another piston fuel pump.

Offenbarung der ErfindungDisclosure of the invention

Erfindungsgemäß ist eine Kolben-Kraftstoffpumpe gemäß Anspruch 1 vorgesehen.According to the invention, a piston fuel pump according to claim 1 is provided.

Insbesondere dichtet die Dichtung einen zwischen Pumpenkolben und Pumpenzylinder vorhandenen Spalt ab.In particular, the seal seals a gap between the pump piston and the pump cylinder.

Unter unmittelbarem Aufbringen wird hierbei insbesondere verstanden, dass das Material der Dichtung in flüssigem Zustand auf den Kolben aufgebracht wird und sich anschließend auf diesem verfestigt, insbesondere in Folge einer Abkühlung erstarrt.In this context, direct application is understood in particular to mean that the material of the seal is applied to the piston in a liquid state and then solidifies on the piston, in particular solidifies as a result of cooling.

Das unmittelbare Aufbringen der Dichtung auf den Pumpenkolben mittels eines Spritzgussverfahrens hat zum einen den Vorteil, dass eine getrennte Herstellung der Dichtung und eine nachfolgende Handhabung und Verbindung mit dem Pumpenkolben entfällt und sich somit die Fertigung vereinfacht. Des Weiteren lassen sich auf diese Weise vielfältige geometrische Ausgestaltungen der Schnittstelle zwischen Dichtung und Pumpenkolben, insbesondere formschlüssige Verbindungen, leicht realisieren.The direct application of the seal to the pump piston by means of an injection molding process has the advantage, on the one hand, that a separate production of the seal and subsequent handling and connection to the pump piston are not required, and production is thus simplified. Furthermore, diverse geometric configurations of the interface between the seal and the pump piston, in particular form-fitting connections, can easily be implemented in this way.

Weiterbildungen der Erfindung sehen vor, dass die Dichtung auch den arbeitsraumseitigen Endabschnitt des Pumpenkolbens gegen den Arbeitsraum abdichtet, insbesondere vollständig abdichtet.Further developments of the invention provide that the seal also seals off the end section of the pump piston on the working space side from the working space, in particular completely sealing it off.

Dadurch, dass die Dichtung den arbeitsraumseitigen Endabschnitt des Pumpenkolbens gegen den Arbeitsraum abdichtet, befindet sich der gesamte Pumpenkolben auf der vom Arbeitsraum abgewandten Seite der Dichtung, also insbesondere in einem Niederdruckbereich. Auf diese Weise wird eine Leckage zwischen Arbeitsraum und Niederdruckbereich, die bei der aus dem Stand der Technik bekannten Pumpe entlang eines zwischen Pumpenkolben und Dichtung verlaufenden Pfades auftreten kann, vollständig und zuverlässig ausgeschlossen.Because the seal seals the end section of the pump piston on the working chamber side from the working chamber, the entire pump piston is located on the side of the seal facing away from the working chamber, that is to say in particular in a low-pressure region. In this way, leakage between the working space and the low-pressure area, which can occur in the pump known from the prior art along a path running between the pump piston and seal, is completely and reliably excluded.

Unter dem arbeitsraumseitigen Endabschnitt des Pumpenkolbens wird vorliegend insbesondere ein Bereich verstanden, der die arbeitsraumseitige Stirnseite des Pumpenkolbens umfasst und ferner einen in axialer Richtung zum Arbeitsraum weisenden Endabschnitt des Pumpenkolbens.In the present case, the end section of the pump piston on the working chamber side is understood in particular to be a region which comprises the end face of the pump piston on the working chamber side and also an end portion of the pump piston pointing in the axial direction towards the working chamber.

Bei einem Pumpenkolben, der als sich zum Arbeitsraum hin verjüngender Stufenkolben, insbesondere mit zylindrischen Teilabschnitten, ausgebildet ist, kann der arbeitsraumseitige Endabschnitt insbesondere der verjüngte Teil des Stufenkolbens und/oder der arbeitsraumseitig der Stufe liegende Bereich des Pumpenkolbens sein.In the case of a pump piston which is designed as a stepped piston tapering towards the working space, in particular with cylindrical sections, the end section on the working space side can in particular be the tapered part of the stepped piston and / or the area of the pump piston on the working space side of the step.

Der arbeitsraumseitige Endabschnitt des Pumpenkolbens kann beispielsweise bezogen auf die Längserstreckung des Pumpenkolbens, also in axialer Richtung, lediglich in der arbeitsraumseitigen Hälfte des Pumpenkolbens ausgebildet sein oder sogar lediglich in dem arbeitsraumseitigen in axialer Richtung äußeren Viertel des Pumpenkolbens.The end section of the pump piston on the working chamber side can, for example, be formed only in the working chamber-side half of the pump piston in relation to the longitudinal extension of the pump piston, i.e. in the axial direction, or even only in the working chamber-side outer quarter of the pump piston in the axial direction.

Das Abdichten des arbeitsraumseitigen Endabschnitts des Pumpenkolbens gegen den Arbeitsraum durch die Dichtung kann dadurch realisiert sein, dass die Dichtung eine Ausnehmung mit insbesondere zylindrischer Grundgestalt aufweist, in der der arbeitsraumseitige Endabschnitt des Pumpenkolbens angeordnet ist und/oder die durch den arbeitsraumseitigen Endabschnitt des Pumpenkolbens ausgefüllt wird, insbesondere vollständig ausgefüllt wird. Mit anderen Worten bedeckt die Dichtung also insbesondere den arbeitsraumseitigen Endabschnitt des Pumpenkolbens sowohl radial als auch auf der dem Arbeitsraum zugewandten Stirnseite des Pumpenkolbens. Die Dichtung hat also, mit nochmals anderen Worten, insbesondere eine becherförmige Innenkontur, in der der arbeitsraumseitige Endabschnitt des Pumpenkolbens angeordnet ist und/oder die durch den arbeitsraumseitigen Endabschnitt des Pumpenkolbens ausgefüllt wird, insbesondere vollständig ausgefüllt wird.The sealing of the working chamber-side end section of the pump piston against the working chamber by the seal can be realized in that the seal has a recess with an especially cylindrical basic shape, in which the working chamber-side end section of the pump piston is arranged and / or which is filled by the working chamber-side end section of the pump piston , in particular is filled in completely. In other words, the seal covers, in particular, the end section of the pump piston on the working space side, both radially and on the end face of the pump piston facing the working space. In other words, the seal has, in particular, a cup-shaped inner contour in which the end section of the pump piston on the working chamber side is arranged and / or which is filled, in particular completely filled, by the end portion of the pump piston on the working chamber side.

Der Begriff "becherförmig" impliziert hierbei insbesondere das Vorhandensein eines stirnseitigen Bodens, der beispielsweise als runde Fläche ausgebildet sein kann, und einer am Rand des Bodens umlaufend angeformten Wand, die insbesondere senkrecht zu dem Boden erstreckt sein kann.The term "cup-shaped" here implies in particular the presence of an end-face base, which can be designed as a round surface, for example, and a wall formed around the edge of the base, which can in particular extend perpendicular to the base.

Der Begriff "zylindrische Grundgestalt" umfasst zwar insbesondere auch tatsächlich geometrisch exakte zylindrische Formen, ist aber grundsätzlich weit, insbesondere im Sinne von "länglich" zu verstehen und stellt keine Einschränkung hinsichtlich von Oberflächenstrukturen dar, die an dem Pumpenkolben und an der Dichtung ausgebildet sein können und auf die weiter unten noch genauer eingegangen wird.The term "cylindrical basic shape" in particular also actually includes geometrically exact cylindrical shapes, but is basically to be understood broadly, in particular in the sense of "elongated" and does not represent any restriction with regard to surface structures that can be formed on the pump piston and on the seal and which will be discussed in more detail below.

Weiterbildungen der Erfindung sehen vor, dass der arbeitsraumseitige Endabschnitt des Pumpenkolbens und die Dichtung zueinander formschlüssig sind. Die Begriffe Formschluss und formschlüssige Verbindung werden dabei im Sinne der VDI 2232 verwendet; insbesondere sind der arbeitsraumseitige Endabschnitt des Pumpenkolben und die Dichtung zueinander formschlüssig, wenn sie aufgrund ihrer Form ineinander verhakt sind.Further developments of the invention provide that the end section of the pump piston on the working space side and the seal are interlocked with one another. The terms form fit and form fit connection are used in the sense of VDI 2232; In particular, the end section of the pump piston on the working space side and the seal are positively locked to one another if they are hooked into one another due to their shape.

Zusätzlich oder alternativ können der arbeitsraumseitige Endabschnitt des Pumpenkolbens und die Dichtung kraftschlüssig miteinander verbunden sein, insbesondere kann die Dichtung unter Spannung auf dem arbeitsraumseitigen Endabschnitt des Pumpenkolbens aufliegen.Additionally or alternatively, the end section of the pump piston on the working space side and the seal can be connected to one another in a force-locking manner, In particular, the seal can rest under tension on the end section of the pump piston on the working space side.

Erfindungsgemäß ist vorgesehen, dass der arbeitsraumseitige Endabschnitt des Pumpenkolbens eine erste Oberflächenstruktur aufweist und die Dichtung eine zweite Oberflächenstruktur aufweist und die erste Oberflächenstruktur und die zweite Oberflächenstruktur zueinander komplementär sind und/oder ineinander eingreifen. Die erste Oberflächenstruktur und die zweite Oberflächenstruktur können sich dabei gegenseitig ausfüllen, insbesondere vollständig ausfüllen.According to the invention, it is provided that the end section of the pump piston on the working space side has a first surface structure and the seal has a second surface structure and the first surface structure and the second surface structure are complementary to one another and / or engage in one another. The first surface structure and the second surface structure can fill one another, in particular fill them completely.

Unter einer Oberflächenstruktur der Dichtung oder des Pumpenkolbens werden hierbei insbesondere geometrische Merkmale verstanden, die nicht die oben bereits diskutierte geometrische Grundgestalt der Dichtung oder des Pumpenkolbens betreffen. Beispielsweise können Oberflächenstrukturen lediglich Merkmale aufweisen, deren Strukturgrößen deutlich kleiner sind, zum Beispiel nicht größer als 10% sind, als Strukturgrößen der Dichtung und/oder des arbeitsraumseitigen Endabschnitts des Pumpenkolbens, zum Beispiel die Gesamtlänge, und/oder der weiteste Durchmesser der Dichtung und/oder des Pumpenkolbens und/oder des arbeitsraumseitigen Endabschnitts des Pumpenkolbens.A surface structure of the seal or the pump piston is understood to mean in particular geometric features that do not relate to the basic geometric shape of the seal or the pump piston already discussed above. For example, surface structures can only have features whose structure sizes are significantly smaller, for example not greater than 10%, than structure sizes of the seal and / or the end section of the pump piston on the working space side, for example the total length and / or the widest diameter of the seal and / or the pump piston and / or the end section of the pump piston on the working chamber side.

Die Oberflächenstruktur der Dichtung ist erfindungsgemäß entweder eine Rillenstruktur und/oder um eine Wellenstruktur, insbesondere mit Rillen und/oder Wellen, die radial um den arbeitsraumseitigen Endabschnitt des Pumpenkolbens umlaufen, oder eine Rändelstruktur, insbesondere eine Kreuzrändelstruktur, die auf einem Pumpenkolben in einfacher Art und Weise aufgebracht werden kann. Der Begriff Rändelstruktur wird insbesondere mit Hinblick auf die DIN 82 von 1973 verstanden. Strukturgrößen von geometrisch regelmäßigen Oberflächenstrukturen in axialer und/oder tangentialer Richtung sind insbesondere durch ihre Periodizität gegeben. Strukturgrößen von geometrisch regelmäßigen Oberflächenstrukturen in radialer Richtung sind insbesondere durch ihre Amplitude gegeben.According to the invention, the surface structure of the seal is either a grooved structure and / or a wave structure, in particular with grooves and / or waves that run radially around the end section of the pump piston on the working space side, or a knurled structure, in particular a cross-knurled structure, which is simple and easy on a pump piston Way can be applied. The term knurled structure is understood in particular with reference to DIN 82 from 1973. Structure sizes of geometrically regular surface structures in the axial and / or tangential direction are given in particular by their periodicity. Structure sizes of geometrically regular surface structures in the radial direction are given in particular by their amplitude.

Insbesondere sind grundsätzlich Oberflächenstrukturen mit Strukturgrößen in radialer Richtung im Bereich von 0,1 mm bis 2 mm vorteilhafterweise möglich. Dabei haben tiefe Strukturen, beispielsweise mit Strukturgrößen in radialer Richtung von 0,5 mm oder mehr, den Vorteil einer besonders wirksamen Verzahnung zwischen dem arbeitsraumseitigen Endabschnitt des Pumpenkolbens und der Dichtung. Flache Strukturen, beispielsweise mit Strukturgrößen in radialer Richtung von 0,5 mm oder weniger, haben dabei hingegen den Vorteil, dass Sie besonders einfach herstellbar sind.In particular, surface structures with structure sizes in the radial direction in the range from 0.1 mm to 2 mm are advantageously possible. Deep structures, for example with structure sizes in the radial direction of 0.5 mm or more, have the advantage of being particularly effective Toothing between the end section of the pump piston on the working chamber side and the seal. On the other hand, flat structures, for example with structure sizes in the radial direction of 0.5 mm or less, have the advantage that they are particularly easy to manufacture.

Besonders vorteilhaft ist es, wenn die Strukturgröße in radialer Richtung, also die Strukturtiefe, im Vergleich zu der Strukturgröße in axialer und/oder tangentialer Richtung ausreichend groß ist, da dies den Effekt einer Verzahnung sicherstellt.It is particularly advantageous if the structure size in the radial direction, ie the structure depth, is sufficiently large in comparison to the structure size in the axial and / or tangential direction, since this ensures the effect of a toothing.

Dies ist insbesondere der Fall, wenn der arbeitsraumseitige Endabschnitt des Pumpenkolbens eine erste Oberflächenstruktur aufweist und die Dichtung eine zweite Oberflächenstruktur aufweist und die erste Oberflächenstruktur und/oder die zweite Oberflächenstruktur eine in radialer Richtung gemessene Strukturtiefe aufweist und eine in tangentialer und/oder axialer Richtung gemessene Strukturgröße aufweist und die in tangentialer und/oder axialer Richtung gemessene Strukturgröße nicht mehr als das 10-fache der Strukturtiefe ist, vorzugsweise sogar nicht mehr als das 5-fache der Strukturtiefe ist.This is particularly the case when the end section of the pump piston on the working space side has a first surface structure and the seal has a second surface structure and the first surface structure and / or the second surface structure has a structure depth measured in the radial direction and one measured in the tangential and / or axial direction Has structure size and the structure size measured in the tangential and / or axial direction is not more than 10 times the structure depth, preferably even not more than 5 times the structure depth.

Die Dichtung kann insbesondere ein thermoplastisches Material aufweisen oder aus einem thermoplastischen Material bestehen. Das thermoplastische Material kann insbesondere ein thermoplastisches Polymer sein, beispielsweise ein faserverstärktes thermoplastisches Polymer. Es kann sich beispielsweise um mit Carbonfaser verstärktes Polyetheretherketon (PEEK) handeln. Ein solches ist beispielsweise PEEK 150CA30. Ein weiteres bevorzugtes thermoplastisches Material ist PA66CF20.The seal can in particular have a thermoplastic material or consist of a thermoplastic material. The thermoplastic material can in particular be a thermoplastic polymer, for example a fiber-reinforced thermoplastic polymer. It can be, for example, polyetheretherketone (PEEK) reinforced with carbon fiber. One such is, for example, PEEK 150CA30. Another preferred thermoplastic material is PA66CF20.

Die Dichtung hat eine Dicke im Bereich von 0,5mm bis 1,8mm um eine hohe Festigkeit, eine geringe Masse und eine einfache Fertigbarkeit gleichermaßen zu gewährleisten.The seal has a thickness in the range from 0.5mm to 1.8mm to ensure high strength, low mass and easy manufacture.

Bei der Kraftstoff-Kolbenpumpe handelt es sich insbesondere um eine Pumpe, die ein Pumpengehäuse aufweist, in dem ein von dem Pumpenkolben begrenzter Arbeitsraum ausgebildet ist. Die Verdichtung des Kraftstoffs erfolgt insbesondere in diesem Arbeitsraum, insbesondere durch eine den Arbeitsraum verkleinernde axiale Bewegung des Pumpenkolbens. Es erfolgt insbesondere eine Verdichtung des Kraftstoff im Arbeitsraum auf ein hohes Druckniveau, beispielsweise auf 100bar bis 600bar.The fuel piston pump is, in particular, a pump that has a pump housing in which a working space delimited by the pump piston is formed. The compression of the fuel takes place in particular in this working space, in particular by an axial movement of the pump piston that reduces the working space. In particular, the fuel in the working chamber is compressed to a high pressure level, for example to 100 bar to 600 bar.

Die erfindungsgemäße Dichtung ist insbesondere zwischen dem Arbeitsraum und einem Niederdruckbereich der Pumpe ausgebildet. Der Druck im Niederdruckbereich ist geringer als das hohe Druckniveau, das im Arbeitsraum der Pumpe generiert wird. Das Druckniveau im Niederdruckbereich kann beispielsweise bei 3bar bis 10bar liegen und durch eine separate Vorpumpe generiert sein.The seal according to the invention is formed in particular between the working space and a low-pressure area of the pump. The pressure in the low pressure area is lower than the high pressure level that is generated in the working area of the pump. The pressure level in the low pressure range can be, for example, 3 to 10 bar and can be generated by a separate backing pump.

Der Arbeitsraum ist insbesondere über ein Auslassventil mit einem Pumpenauslass verbunden und insbesondere über ein elektrisch ansteuerbares Einlassventil mit einem Pumpeneinlass verbunden. Das elektrisch ansteuerbare Einlassventil kann insbesondere als Mengensteuerventil ausgebildet sein. Optional kann zusätzlich zwischen Pumpeneinlass und Arbeitsraum ferner eine Dämpfungseinrichtung zur Dämpfung von Pulsationen im Niederdruckbereich der Pumpe vorgesehen sein.The working space is connected in particular to a pump outlet via an outlet valve and in particular connected to a pump inlet via an electrically controllable inlet valve. The electrically controllable inlet valve can in particular be designed as a quantity control valve. Optionally, a damping device for damping pulsations in the low-pressure region of the pump can also be provided between the pump inlet and the working chamber.

Die Dämpfungseinrichtung zur Dämpfung von Pulsationen im Niederdruckbereich kann beispielsweise ein zwischen zwei Membranen eingeschlossenes Gasvolumen umfassen, Details hinsichtlich der Dämpfungseinrichtung können wie in der DE10327408A1 gezeigt ausgebildet sein.The damping device for damping pulsations in the low-pressure range can, for example, comprise a gas volume enclosed between two membranes; details regarding the damping device can be as in FIG DE10327408A1 be formed shown.

Ein weiteres zwischen Pumpenauslass und Arbeitsraum angeordnetes Ventil, das antiparallel zum Auslassventil angeordnet ist, kann vorgesehen sein und insbesondere als Druckbegrenzungsventil für einen mit der Pumpe verbindbaren Hochdruckspeicher wirken.Another valve arranged between the pump outlet and the working chamber, which is arranged antiparallel to the outlet valve, can be provided and in particular act as a pressure limiting valve for a high-pressure accumulator that can be connected to the pump.

Vorzugsweise sind das Auslassventil und/oder das Einlassventil und/oder das Druckbegrenzungsventil ortsfest zu dem Pumpengehäuse und insofern auch ortsfest zu dem Pumpenzylinder fixiert. Eine Fixierung dieser Komponenten an dem Pumpenkolben scheidet insofern insbesondere aus. Es ergibt sich der Vorteil, dass die Masse des Pumpenkolbens gering ist und somit die Dynamik bzw. Leichtgängigkeit der Pumpe verbessert ist.The outlet valve and / or the inlet valve and / or the pressure limiting valve are preferably fixed in a fixed position to the pump housing and, to this extent, also fixed in a fixed position to the pump cylinder. A fixation of these components on the pump piston is excluded in particular. There is the advantage that the mass of the pump piston is low and thus the dynamics or ease of movement of the pump is improved.

Vorzugsweise ist zusätzlich oder alternativ der Pumpenkolben als Vollkörper ausgebildet, sodass er den bei der Kraftstoffeinspritzung, insbesondere bei der Benzindirekteinspritzung, hohen wirkenden Drücken ohne Verformung standhalten kann. Eine Durchströmbarkeit des Pumpenkolbens in Längsrichtung scheidet insofern aus.In addition or as an alternative, the pump piston is preferably designed as a solid body so that it can withstand the high pressures that act during fuel injection, in particular during gasoline direct injection, without deformation. A permeability of the pump piston in the longitudinal direction is ruled out in this respect.

Weitere Details der Anordnung von Arbeitsraum, Auslassventil und Druckbegrenzungsventil zueinander und im Pumpenkörper können beispielsweise wie in der DE102004013307A1 gezeigt ausgebildet sein.Further details of the arrangement of the working chamber, outlet valve and pressure relief valve to one another and in the pump body can be, for example, as in FIG DE102004013307A1 be formed shown.

Der Pumpenzylinder kann in einer im Pumpenkörper fixierten Buchse ausgebildet sein. Alternativ kann der Pumpenzylinder auch unmittelbar im Pumpenkörper vorgesehen sein.The pump cylinder can be formed in a bushing fixed in the pump body. Alternatively, the pump cylinder can also be provided directly in the pump body.

Der Pumpenkörper, der Pumpenkolben, der Pumpenzylinder, und/oder alle Pumpenteile, die mit dem Kraftstoff in Berührung kommen, bestehen bevorzugt lediglich aus Stählen und aus Kunstoffen, sodass im Ergebnis eine hohe Beständigkeit auch gegenüber ethanolhaltigen Kraftstoffen und/oder anderen aggressiven Kraftstoffen gegeben ist.The pump body, the pump piston, the pump cylinder and / or all pump parts that come into contact with the fuel are preferably only made of steel and plastic, so that the result is high resistance to fuels containing ethanol and / or other aggressive fuels .

Anderen Weiterbildungen der Erfindung liegt die Zielsetzung zugrunde, die Lebensdauer der Kolben-Kraftstoffpumpe zu maximieren. Ferner wurde erkannt, dass ein im Bereich der Dichtung auftretender Verschleiß maßgeblich durch die zwischen der Dichtung und dem Pumpenzylinder auftretende Reibung verursacht wird.Other developments of the invention are based on the objective of maximizing the service life of the piston fuel pump. It was also recognized that wear that occurs in the area of the seal is largely caused by the friction that occurs between the seal and the pump cylinder.

Die dabei auftretenden Reibphänomene lassen sich je nach Art der auftretenden Kontaktzustände der Reibpartner, hier der Dichtung und des Pumpenzylinders, gemäß der DIN 50281 in Klassen bzw. Phasen einteilen.The friction phenomena that occur can be divided into classes or phases according to DIN 50281, depending on the type of contact conditions between the friction partners, here the seal and the pump cylinder.

So tritt bei der sogenannten Festkörperreibung ein unmittelbarer Kontakt zwischen den Reibpartnern auf. Die auftretenden Reibkräfte und der resultierende Verschleiß sind entsprechend hoch.In so-called solid body friction, there is direct contact between the friction partners. The frictional forces that occur and the resulting wear are correspondingly high.

Bei der Flüssigkeitsreibung hingegen tritt ein unmittelbarer Kontakt zwischen den Reibpartnern nicht mehr auf. Die Reibpartner sind durch ein flüssiges Medium voneinander getrennt, beispielsweise durch einen durchgängigen Flüssigkeitsfilm, vorliegend beispielsweise durch einen durchgängigen Kraftstofffilm. Die auftretenden Reibkräfte sind hierbei in der Regel erheblich geringer als bei der Festkörperreibung. Entsprechend ist auch der auftretende Verschleiß an den Reibungspartnern entsprechend vermindert.With fluid friction, however, there is no longer any direct contact between the friction partners. The friction partners are separated from one another by a liquid medium, for example by a continuous liquid film, in the present case for example by a continuous fuel film. The frictional forces that occur are usually considerably lower than with solid body friction. The wear that occurs on the friction partners is correspondingly reduced.

Ferner kann auch Mischreibung auftreten, die zeitlich und/oder räumlich nebeneinander Anteile der Festkörperreibung und Anteile der Flüssigkeitsreibung aufweist.Furthermore, mixed friction can also occur which, temporally and / or spatially, has proportions of solid body friction and proportions of liquid friction.

In der Regel ist davon auszugehen, dass die Dichtung an dem Pumpenzylinder zur Anlage kommt, wenn sie relativ zu dem Pumpenzylinder in Ruhe ist, beispielsweise in den Umkehrpunkten des Pumpenkolbens. Zu Beginn einer Relativbewegung zwischen Pumpenkolben und Pumpenzylinder ist daher das zumindest kurzfristige Auftreten von Festkörperreibung zwischen Dichtung und Pumpenzylinder kaum vermeidbar.As a rule, it can be assumed that the seal comes to rest on the pump cylinder when it is at rest relative to the pump cylinder, for example at the reversal points of the pump piston. At the beginning of a relative movement between the pump piston and the pump cylinder, the occurrence of solid-state friction between the seal and the pump cylinder, at least for a short time, can hardly be avoided.

Diese Weiterbildungen basieren weiterhin auf der Erkenntnis, dass die Phasen, in denen Festkörperreibung zwischen der Dichtung und dem Pumpenzylinder auftritt, minimiert werden sollten.These developments are also based on the knowledge that the phases in which solid-state friction occurs between the seal and the pump cylinder should be minimized.

Insbesondere wird dies dadurch gelöst, dass eine radial außen liegende Fläche der Dichtung, die einer Innenfläche des Pumpenzylinders gegenüberliegt, in einem axialen Endbereich der Dichtung so ausgebildet ist, dass sie bei relativ zum Pumpenzylinder ruhendem Pumpenkolben an dem Pumpenzylinder anliegt und dass eine Relativbewegung zwischen Pumpenzylinder und Pumpenkolben in axialer Richtung ein Abheben der Dichtung von dem Pumpenkolben in eine radial nach innen weisende Richtung begünstigt.In particular, this is achieved in that a radially outer surface of the seal, which lies opposite an inner surface of the pump cylinder, is designed in an axial end region of the seal in such a way that it rests against the pump cylinder when the pump piston is stationary relative to the pump cylinder and that a relative movement between the pump cylinder and the pump piston in the axial direction favors a lifting of the seal from the pump piston in a radially inward direction.

Dies lässt sich insbesondere durch die Maßnahme erreichen, dass eine radial außen liegende Fläche der Dichtung, die einer Innenfläche des Pumpenzylinders gegenüberliegt, in einem axialen Endbereich der Dichtung unter einem Winkel von 10° bis 60° zur Innenwand des Pumpenzylinders radial nach innen geneigt ist. Der von dem Pumpenkolben zu verdichtende Kraftstoff übt hierbei insbesondere eine nach radial innen wirkende Kraft auf die radial außen liegende Fläche der Dichtung aus, sodass diese von dem Pumpenzylinder insbesondere etwas abheben kann und sich ein Kraftstofffilm zwischen Dichtung und Pumpenzylinder insbesondere ausbilden kann.This can be achieved in particular by the measure that a radially outer surface of the seal, which is opposite an inner surface of the pump cylinder, is inclined radially inward in an axial end region of the seal at an angle of 10 ° to 60 ° to the inner wall of the pump cylinder. The fuel to be compressed by the pump piston exerts, in particular, a radially inward force on the radially outer surface of the seal, so that it can in particular lift slightly from the pump cylinder and a fuel film can in particular form between the seal and the pump cylinder.

Nachfolgend werden Beispiele der vorliegenden Erfindung unter Bezugnahme auf die beiliegenden Zeichnungen näher erläutert.Examples of the present invention are explained in more detail below with reference to the accompanying drawings.

In den Zeichnungen zeigen:

Figur 1
eine schematische Darstellung eines Kraftstoffsystems einer Brennkraftmaschine mit einem Ausschnitt einer erfindungsgemäßen Kolben-Kraftstoffpumpe
Figur 2
eine vergrößerte Schnittdarstellung des Ausschnitts der Kolben-Kraftstoffpumpe gemäß Figur 1
Figur 3a
eine Ausführungsform der Kolben-Kraftstoffpumpe
Figur 3b - f
erfindungsgemäße Ausführungsform der Kolben-Kraftstoffpumpe
In the drawings show:
Figure 1
a schematic representation of a fuel system of an internal combustion engine with a section of a piston fuel pump according to the invention
Figure 2
an enlarged sectional view of the detail of the piston fuel pump according to Figure 1
Figure 3a
an embodiment of the piston fuel pump
Figure 3b - f
embodiment of the piston fuel pump according to the invention

In der Figur 4 ist eine Dichtlippe der Dichtung vergrößert dargestellt.In the Figure 4 a sealing lip of the seal is shown enlarged.

AusführungsformenEmbodiments

Ein Kraftstoffsystem einer Brennkraftmaschine trägt in Figur 1 insgesamt das Bezugszeichen 10. Es umfasst einen Kraftstoffbehälter 12, aus dem eine elektrische Vorförderpumpe 14 den Kraftstoff in eine Niederdruckleitung 16 fördert. Diese führt zu einer Hochdruckpumpe in Form einer Kolben-Kraftstoffpumpe 18. Von dieser führt eine Hochdruckleitung 20 zu einem Kraftstoffrail 22. An dieses sind mehrere Injektoren 24 angeschlossen, die den Kraftstoff direkt in ihnen jeweils zugeordnete Brennräume (nicht dargestellt) einspritzen.A fuel system of an internal combustion engine contributes to Figure 1 generally the reference numeral 10. It comprises a fuel tank 12, from which an electrical prefeed pump 14 conveys the fuel into a low-pressure line 16. This leads to a high pressure pump in the form of a piston fuel pump 18. From this a high pressure line 20 leads to a fuel rail 22. A plurality of injectors 24 are connected to this, which inject the fuel directly into combustion chambers (not shown) assigned to them.

Die Kolben-Kraftstoffpumpe 18 umfasst ein nur bereichsweise angedeutetes Pumpengehäuse 26, in dem ein Pumpenkolben 28 verschiebbar geführt bzw. gelagert ist. Dieser kann von einem nicht dargestellten Nockenantrieb in eine Hin- und Herbewegung versetzt werden, was durch einen seitlich gezeichneten Doppelpfeil 30 angedeutet ist. Der Pumpenkolben 28 wird von einer Schraubenfeder 32 in einen in Figur 1 unteren Totpunkt beaufschlagt. Der Pumpenkolben 28 und das Pumpengehäuse 26 begrenzen einen Arbeitsraum 34. Dieser Arbeitsraum 34 ist über ein Einlassventil 36 mit der Niederdruckleitung 16 verbindbar. Ferner ist der Arbeitsraum 34 über ein Auslassventil 38 mit der Hochdruckleitung 20 verbindbar.The piston fuel pump 18 comprises a pump housing 26, only partially indicated, in which a pump piston 28 is displaceably guided or mounted. This can be set in a back and forth movement by a cam drive (not shown), which is indicated by a double arrow 30 drawn on the side. The pump piston 28 is converted into an in Figure 1 applied to lower dead center. The pump piston 28 and the pump housing 26 delimit a working space 34. This working space 34 can be connected to the low-pressure line 16 via an inlet valve 36. Furthermore, the working chamber 34 can be connected to the high-pressure line 20 via an outlet valve 38.

Sowohl das Einlassventil 36 als auch das Auslassventil 38 sind als Rückschlagventile ausgeführt. Nicht dargestellt, aber möglich ist dabei eine Ausführung des Einlassventils 36 als Mengensteuerventil. Bei einem solchen kann das Einlassventil 36 während eines Förderhubs des Pumpenkolbens 28 zwangsweise geöffnet werden, so dass der Kraftstoff nicht in das Kraftstoffrail 22, sondern zurück in die Niederdruckleitung 16 gefördert wird. Hierdurch kann die von der Kolben-Kraftstoffpumpe 18 in das Kraftstoffrail 22 geförderte Kraftstoffmenge eingestellt werden.Both the inlet valve 36 and the outlet valve 38 are designed as check valves. An embodiment of the inlet valve 36 as a quantity control valve is not shown, but possible. In such a case, the inlet valve 36 can be forcibly opened during a delivery stroke of the pump piston 28, so that the fuel is not delivered into the fuel rail 22, but back into the low-pressure line 16. In this way, the amount of fuel delivered by the piston fuel pump 18 into the fuel rail 22 can be adjusted.

Der Pumpenkolben 28 ist in einem Pumpenzylinder 40 geführt, der insoweit Teil des Pumpengehäuses 26 ist. Der Pumpenkolben 28 weist an einem dem Arbeitsraum 34 zugewandten Ende einen in Figur 1 oben angeordneten Endabschnitt 42 auf. In der Umgebung dieses arbeitsraumseitigen Endabschnitts 42 weist der Pumpenkolben 28 ferner einen kreisringartigen Absatz 44 in der Art eines radial abstehenden umlaufenden Kragens auf. Eine Dichtung 46 kommt an dem Pumpenkolben 28 bzw. an dem Absatz 44 zur Anlage und umschließt den arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 axial und radial. Dadurch wird der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28, vollständig gegen den Arbeitsraum 34 abgedichtet, ein im Arbeitsraum befindliches Medium kommt also mit dem arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 nicht in Berührung und ein im Arbeitsraum wirksamer hydraulischer Druck wirkt also auf den arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 nicht mehr oder nur noch mittelbar über die Dichtung 46 ein.The pump piston 28 is guided in a pump cylinder 40, which in this respect is part of the pump housing 26. The pump piston 28 has an end facing the working chamber 34 in Figure 1 end portion 42 arranged above. In the vicinity of this end section 42 on the working space side, the pump piston 28 furthermore has an annular shoulder 44 in the manner of a radially protruding circumferential collar. A seal 46 comes to rest on the pump piston 28 or on the shoulder 44 and surrounds the end section 42 of the pump piston 28 on the working space side axially and radially. As a result, the end section 42 of the pump piston 28 on the work space side is completely sealed off from the work space 34, i.e. a medium located in the work space does not come into contact with the end section 42 of the pump piston 28 on the work space side and a hydraulic pressure effective in the work space thus acts on the end section 42 of the work space Pump piston 28 no longer or only indirectly via seal 46.

An seinem vom Arbeitsraum 34 abgewandten Ende weist der Pumpenkolben 28 ferner einen in Figur 1 unteren Endabschnitt 52 auf. In der Umgebung dieses unteren Endabschnitts 52 ist eine Führungshülse 54 am Pumpengehäuse 26 fest angeordnet. Zwischen der Führungshülse 54 und dem Pumpengehäuse 26 ist eine O-Ring-Dichtung 56 in einer Nut 58 vorgesehen. Die Führungshülse 54 weist einen Zylinderabschnitt 60 auf, der sich koaxial zum Pumpenkolben28 erstreckt und durch welchen die Schraubenfeder 32 geführt ist. Die Schraubenfeder 32 taucht entlang einer Kolbenlängsachse 62 zumindest abschnittsweise in eine Federaufnahmenut 64 der Führungshülse 54 ein, wo sie sich gegen die Führungshülse 54 axial abstützt.At its end facing away from the working chamber 34, the pump piston 28 also has an in Figure 1 lower end portion 52. In the vicinity of this lower end section 52, a guide sleeve 54 is fixedly arranged on the pump housing 26. An O-ring seal 56 is provided in a groove 58 between the guide sleeve 54 and the pump housing 26. The guide sleeve 54 has a cylinder section 60 which extends coaxially to the pump piston 28 and through which the helical spring 32 is guided. The helical spring 32 dips along a piston longitudinal axis 62, at least in sections, into a spring receiving groove 64 of the guide sleeve 54, where it is axially supported against the guide sleeve 54.

Die Führungshülse 54 weist ferner im Inneren einen kreiszylindrischen Aufnahmeabschnitt 66 auf, der im Wesentlichen durch die innere Umfangswand des Zylinderabschnitts 60 gebildet wird. In diesem Aufnahmeabschnitt 66 ist ein ringförmiges Dichtelement 68 relativ zum Pumpengehäuse 26 ortsfest angeordnet, wobei das Dichtelement 68 einen H-förmigen Querschnitt hat. In einem sich am abragenden Ende des Zylinderabschnitts nach radial einwärts erstreckenden Kragenabschnitt 70 ist ferner ein Führungselement 72 ebenfalls relativ zum Pumpengehäuse 26 ortsfest angeordnet. Dieses somit in axialer Richtung des Pumpenkolbens 28 gesehen von der Dichtung 46 deutlich beabstandete Führungselement 72 stellt zusammen der Dichtung 46 die Führung bzw. Zweipunktlagerung des Pumpenkolbens 28 bereit.The guide sleeve 54 also has in the interior a circular cylindrical receiving section 66 which extends essentially through the inner peripheral wall of the cylinder portion 60 is formed. In this receiving section 66, an annular sealing element 68 is arranged in a stationary manner relative to the pump housing 26, the sealing element 68 having an H-shaped cross section. In a collar section 70 extending radially inward at the protruding end of the cylinder section, a guide element 72 is also arranged in a stationary manner relative to the pump housing 26. This guide element 72, which is clearly spaced apart from the seal 46 in the axial direction of the pump piston 28, together provides the seal 46 with the guidance or two-point mounting of the pump piston 28.

Die Ausgestaltung der Dichtung 46 und ihrer Montage auf dem Pumpenkolben ist vorliegend von besonderer Bedeutung. Auf diese Aspekte wird daher unter Bezugnahme auf die nachfolgenden Figuren 2 - 4 im Detail eingegangen.The configuration of the seal 46 and its assembly on the pump piston is of particular importance here. Reference is therefore made to these aspects with reference to the following Figures 2 - 4 received in detail.

Figur 2 zeigt eine Schnittdarstellung eines Ausschnitts der Kolben-Kraftstoffpumpe 18, wobei der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28 und die Dichtung 46 vergrößert zu erkennen sind. Figure 2 shows a sectional view of a detail of the piston fuel pump 18, the working chamber-side end section 42 of the pump piston 28 and the seal 46 being shown enlarged.

Die Dichtung 46 weist eine Ausnehmung 74 mit zylindrischer Gestalt auf, die durch den arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 vollständig ausgefüllt wird, sodass in Zusammenwirken mit der zwischen Dichtung 46 und Pumpenzylinder 40 bestehenden Dichtfunktion der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28, vollständig gegen den Arbeitsraum 34 abgedichtet ist. Dabei bedeckt die Dichtung 46 eine Stirnseite 421 des arbeitsraumseitigen Endabschnitts 42 des Pumpenkolbens 28 und in unmittelbarer Anformung eine Mantelfläche 422 des arbeitsraumseitigen Endabschnitts 42 des Pumpenkolbens 28, sodass der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28 durch die Dichtung 46 vollständig bedeckt ist.The seal 46 has a recess 74 with a cylindrical shape, which is completely filled by the end section 42 of the pump piston 28 on the work space side, so that in cooperation with the sealing function existing between the seal 46 and the pump cylinder 40, the end section 42 of the pump piston 28 on the work space side completely against the work space 34 is sealed. In this case, the seal 46 covers an end face 421 of the end section 42 of the pump piston 28 on the work space side and, in direct molding, a jacket surface 422 of the end section 42 of the pump piston 28 on the work space side, so that the end section 42 of the pump piston 28 on the work space side is completely covered by the seal 46.

Radial außen an der Dichtung 46 ist eine Dichtlippe 50 vorgesehen, die mit dem Pumpenzylinder 40 dichtend zusammenwirkt.A sealing lip 50 is provided radially on the outside of the seal 46 and cooperates in a sealing manner with the pump cylinder 40.

Die Dichtung 46 besteht in diesem Beispiel aus dem faserverstärkten thermoplastischen Polymer PEEK 150CA30 oder PA66CF20. Die Dichtung 46 ist durch ein Spritzgussverfahren hergestellt, bei dem das verflüssigte thermoplastische Polymer in axialer Anspritzrichtung, entlang der Kolbenlängsachse 62, auf den arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 unmittelbar aufgebracht wird. Es kann hierfür beispielsweise ein Heißkanal-Werkzeug verwendet werden, bei dem das geschmolzene thermoplastische Polymer in eine zwischen dem arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 und einer Spritzgussform ausgebildete Kavität mit relativ hoher Temperatur eingebracht wird. Im Anschluss an die Abkühlung und Erstarrung des thermoplastischen Polymers kann der Spritzgussform der Pumpenkolben 28 mit der an ihm festgelegten Dichtung 46 entnommen werden. Die Dichtung 46 hat eine Dicke d von einem Millimeter, um eine hohe Festigkeit, eine geringe Masse und eine einfache Fertigbarkeit gleichermaßen zu gewährleisten.In this example, the seal 46 consists of the fiber-reinforced thermoplastic polymer PEEK 150CA30 or PA66CF20. The seal 46 is produced by an injection molding process, in which the liquefied thermoplastic polymer in the axial injection direction, along the Piston longitudinal axis 62, is applied directly to the end section 42 of the pump piston 28 on the working chamber side. For example, a hot runner tool can be used for this, in which the melted thermoplastic polymer is introduced at a relatively high temperature into a cavity formed between the end section 42 of the pump piston 28 on the working space side and an injection mold. After the thermoplastic polymer has cooled and solidified, the pump piston 28 with the seal 46 attached to it can be removed from the injection mold. The seal 46 has a thickness d of one millimeter in order to ensure high strength, low mass and simple manufacture at the same time.

In diesem Beispiel weisen der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28 und die mit diesem in Kontakt stehende Innenkontur der Ausnehmung 74 der Dichtung 46 eine weitgehend glatte Oberfläche auf. In Figur 3a, die den Ausschnitt X aus Figur 2 wiedergibt, ist dies nochmals vergrößert dargestellt.In this example, the end section 42 of the pump piston 28 on the working space side and the inner contour of the recess 74 of the seal 46 that is in contact therewith have a largely smooth surface. In Figure 3a showing the section X from Figure 2 reproduces, this is shown enlarged again.

Die nachfolgenden Ausführungsbeispiele der Erfindung unterscheiden sich von dem Vorangehenden durch modifizierte Oberflächenstrukturen auf dem arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 und auf der Innenkontur der Dichtung 46.The following exemplary embodiments of the invention differ from the preceding in the modified surface structures on the end section 42 of the pump piston 28 on the working space side and on the inner contour of the seal 46.

In Figur 3b weisen der arbeitsraumseitige Endabschnitt 42 des Pumpenkolbens 28 und die Innenkontur der Dichtung 46 umlaufende Rillen auf. Die Rillen haben eine Tiefe t von 0,5mm und eine Periodizität in axialer Richtung x von 1mm. Es kann sich um eine Vielzahl von Rillen handeln, die jeweils in sich selbst geschlossen umlaufen. Die umlaufenden Rillen können aber auch in ihrer Gesamtheit ein ein- oder mehrgängiges Gewinde darstellen. Die auf der Oberfläche des auf dem arbeitsraumseitigen Endabschnitts 42 des Pumpenkolbens 28 ausgebildete Rillenstruktur ist auf der Innenkontur der Dichtung 46 ersichtlich komplementär, also als Negativbild, ausgebildet, was sich vorliegend im Spritzguss auf natürliche Art und Weise ergibt.In Figure 3b the end section 42 of the pump piston 28 on the working space side and the inner contour of the seal 46 have circumferential grooves. The grooves have a depth t of 0.5 mm and a periodicity in the axial direction x of 1 mm. It can be a large number of grooves, each of which runs around in a closed manner. The circumferential grooves can, however, also represent a single or multiple thread in their entirety. The groove structure on the surface of the end section 42 of the pump piston 28 on the working space side is clearly complementary on the inner contour of the seal 46, that is, as a negative image, which in the present case results naturally in injection molding.

In einer andere Ausführungsform, die besonders einfach herzustellen ist, haben die Rillen eine Tiefe t von nur 0,1mm und eine Periodizität in axialer Richtung x von 1mm.In another embodiment, which is particularly easy to manufacture, the grooves have a depth t of only 0.1 mm and a periodicity in the axial direction x of 1 mm.

Bei einer wiederum anderen Ausführungsform, die eine besonders gute Verzahnung zwischen dem arbeitsraumseitigen Endabschnitts 42 des Pumpenkolbens 28 und der Dichtung 46 gewährleistet, haben die Rillen eine Tiefe t von 2mm und eine Periodizität in axialer Richtung x von 9mm. Diese Rillen können auch als Wellen ausgebildet sein, siehe Figur 3c.In yet another embodiment, which ensures particularly good interlocking between the end section 42 of the pump piston 28 on the working space side and the seal 46, the grooves have a depth t of 2 mm and a periodicity in the axial direction x of 9 mm. These grooves can also be designed as waves, see Figure 3c .

Beispiele arbeitsraumseitiger Endabschnitte 42 von Pumpenkolben 28 mit relativ großen Rillen, die voneinander weiter beabstandet sind, sind in den Figuren 3d und 3e gezeigt.Examples of end sections 42 of the pump piston 28 on the working space side with relatively large grooves which are further spaced apart are shown in FIG Figures 3d and 3e shown.

Alternativ zu Rillenstrukturen können auf dem arbeitsraumseitigen Endabschnitt 42 des Pumpenkolbens 28 und auf der Innenkontur der Dichtung 46 auch Rändelstrukturen oder eine Kreuzrändelstrukturen vorgesehen sein. Ein Beispiel eines solchen arbeitsraumseitigen Endabschnitts 42 eines Pumpenkolbens 28 ist in der Figur 3f gezeigt.As an alternative to groove structures, knurled structures or a cross-knurled structure can also be provided on the end section 42 of the pump piston 28 on the working space side and on the inner contour of the seal 46. An example of such an end section 42 of a pump piston 28 on the working space side is shown in FIG Figure 3f shown.

Neben den vorangehend gezeigten regelmäßigen Oberflächenstrukturen können selbstverständlich auch unregelmäßige Oberflächenstrukturen auf dem arbeitsraumseitigen Endabschnitts 42 des Pumpenkolbens 28 und auf der Innenkontur der Dichtung 46 vorgesehen sein, die insbesondere eine Rauigkeit des Pumpenkolbens 28 und der Dichtung 46 darstellen. In einem Beispiel beträgt der Pt-Wert einer Vermessung der Oberfläche des Pumpenkolbens 0,2mm und die Wellenlänge, bei der das Maximum einer spektralen Zerlegung der Oberflächenrauigkeit (Ra-Spektrum) auftritt, liegt bei 1mm.In addition to the regular surface structures shown above, irregular surface structures can of course also be provided on the end section 42 of the pump piston 28 on the working space side and on the inner contour of the seal 46, which in particular represent a roughness of the pump piston 28 and the seal 46. In one example, the Pt value of a measurement of the surface of the pump piston is 0.2 mm and the wavelength at which the maximum of a spectral decomposition of the surface roughness (Ra spectrum) occurs is 1 mm.

Mit Bezug auf Figur 4 wird nun noch auf die Feingeometrie der Dichtlippe 50 der in den vorangehenden Ausführungsformen dargestellten Dichtungen eingegangen.Regarding Figure 4 the fine geometry of the sealing lip 50 of the seals shown in the previous embodiments will now be discussed.

Ein axialer Endbereich 464 der Dichtung 46 ist vorliegend arbeitsraumseitig an der Dichtlippe 50 ausgebildet. Es ist vorgesehen, dass eine radial außen liegende Fläche der Dichtung 46, die einer Innenfläche des Pumpenzylinder 40 gegenüberliegt, in einem axialen Endbereich 464 der Dichtung 46 unter einem Winkel α von 10° bis 60° zur Innenwand des Pumpenzylinders 40 radial nach innen geneigt ist. Dies hat zur Wirkung oder alternativ ist vorgesehen, dass eine Relativbewegung zwischen Pumpenzylinder 40 und Pumpenkolben 28 in axialer Richtung, insbesondere in Richtung auf den Arbeitsraum 34 zu, ein Abheben der Dichtung 46 von dem Pumpenzylinder 28 in eine radial nach innen weisende Richtung begünstigt. In diesem Fall bildet sich zwischen Dichtung 46 und Pumpenzylinder 40 ein aus Kraftstoff bestehender Flüssigkeitsfilm aus, der bei geringfügiger Leckage den Verschleiß der Kolben-Kraftstoffpumpe 18 erheblich vermindert.An axial end region 464 of the seal 46 is formed in the present case on the working space side on the sealing lip 50. It is provided that a radially outer surface of the seal 46, which is opposite an inner surface of the pump cylinder 40, is inclined radially inward in an axial end region 464 of the seal 46 at an angle α of 10 ° to 60 ° to the inner wall of the pump cylinder 40 . This has the effect or alternatively it is provided that a relative movement between pump cylinder 40 and pump piston 28 in an axial direction Direction, in particular in the direction of the working chamber 34, favors a lifting of the seal 46 from the pump cylinder 28 in a radially inwardly pointing direction. In this case, a liquid film consisting of fuel is formed between the seal 46 and the pump cylinder 40, which, in the event of a slight leak, considerably reduces the wear on the piston fuel pump 18.

Zu diesem Zweck ist an bzw. auf der Dichtlippe 50 ein nach außen weisender, umlaufender Steg 468 einstückig angeformt, der im Querschnitt in Längsrichtung etwa die Form eines gleichschenkligen Dreiecks aufweist, von dem die zwei gegenüberliegenden spitze Ecken in axiale Richtungen weisen und dessen dritte stumpfe Ecke an dem Pumpenzylinder 40 (statisch) anliegt. Es ist vorgesehen, dass lediglich dieser Steg (statisch) an dem Pumpenzylinder 40 zur Anlage kommt, während die Dichtung 46 bzw. die Dichtlippe 50 im Übrigen durch einen Spalt 77 von dem Pumpenzylinder 40 beabstandet ist. Eine Breite s des Spalts 77 beträgt beispielsweise 20µm. Bei Relativbewegung ist, wie oben geschildert, ferner auch ein Abheben des Stegs 468 von dem Pumpenzylinder 40 vorgesehen.For this purpose, an outwardly facing, circumferential web 468 is integrally formed on or on the sealing lip 50, which has the shape of an isosceles triangle in cross section in the longitudinal direction, of which the two opposite pointed corners point in axial directions and the third is obtuse Corner on the pump cylinder 40 (static) rests. It is provided that only this web (statically) comes into contact with the pump cylinder 40, while the seal 46 or the sealing lip 50 is otherwise spaced apart from the pump cylinder 40 by a gap 77. A width s of the gap 77 is 20 μm, for example. In the event of a relative movement, as described above, a lifting of the web 468 from the pump cylinder 40 is also provided.

Claims (13)

  1. Piston fuel pump (18) for an internal combustion engine having a pump cylinder (40) and a pump piston (28), which can be moved axially in the pump cylinder (40), and having a working chamber (34) delimited by the pump piston (28), wherein there is a seal (46) on the pump piston (28), which seals the working chamber (34) off from a low-pressure region, characterized in that the seal (46) is applied directly to the pump piston (28) by means of an injection moulding method, and in that the end section (42) of the pump piston (28) adjacent to the working chamber has a first surface structure (68) and the seal (46) has a second surface structure (86), and the first surface structure (68) and the second surface structure (86) are complementary to one another and/or engage in one another; and in that the first surface structure (68) is a knurled structure or in that the first surface structure (68) is a groove or wave structure running radially around the end section (42) of the pump piston (28).
  2. Piston fuel pump (18) according to Claim 1, characterized in that the seal (46) seals off the end region (42) of the pump piston (28) adjacent to the working chamber completely from the working chamber (34).
  3. Piston fuel pump (18) according to Claim 1 or 2, characterized in that the end section (42) of the pump piston (28) adjacent to the working chamber has a cylindrical basic shape, and the seal (46) has a recess (72) with a cylindrical basic structure, in which the end section (42) of the pump piston (28) adjacent to the working chamber is arranged.
  4. Piston fuel pump (18) according to Claim 1 or 2, characterized in that the end section (42) of the pump piston (28) adjacent to the working chamber has a cylindrical basic shape, and the seal (46) has a recess (72) with a cylindrical basic structure, which is filled by the end section (42) of the pump piston (28) adjacent to the working chamber.
  5. Piston fuel pump (18) according to one of the preceding claims, characterized in that the end section (42) of the pump piston (28) adjacent to the working chamber and the seal (46) are in positive engagement with one another.
  6. Piston fuel pump (18) according to one of the preceding claims, characterized in that the first surface structure (68) and the second surface structure (86) fill each other.
  7. Piston fuel pump (18) according to one of the preceding claims, characterized in that the first surface structure (68) and the second surface structure (86) have a structure depth (t) in a range of from 0.1 mm to 2 mm, measured in a radial direction.
  8. Piston fuel pump (18) according to one of the preceding claims, characterized in that the first surface structure (68) and the second surface structure (86) have a periodicity in a range of from 0.4 mm to 8 mm.
  9. Piston fuel pump (18) according to one of the preceding claims, characterized in that the first surface structure (68) and the second surface structure (86) have a structure depth (t), measured in a radial direction, and have a periodicity, and the periodicity is a multiple (v) of the structure depth (t), measured in a radial direction, wherein the multiple is a factor of two to ten.
  10. Piston fuel pump (18) according to one of the preceding claims, characterized in that the seal (46) is held nonpositively on the end section (42) of the pump piston (28) adjacent to the working chamber.
  11. Piston fuel pump (18) according to one of the preceding claims, characterized in that the seal (46) comprises a thermoplastic material, in particular a fibre-reinforced thermoplastic material, e.g. a polyetheretherketone reinforced with carbon fibres.
  12. Piston fuel pump (18) according to one of the preceding claims, characterized in that the seal (46) has an annular basic structure and is moulded directly onto the end section (42) of the pump piston (28) adjacent to the working chamber by means of injection moulding in an axial moulding direction.
  13. Piston fuel pump (18) according to one of the preceding claims, characterized in that a radially outer surface of the seal (46), which is situated opposite an inner surface of the pump cylinder (40), is designed in such a way in an axial end region (464) of the seal (46) that it rests on the pump cylinder (40) when the pump piston (28) is at rest relative to the pump cylinder (40) and that a relative movement between the pump cylinder (40) and the pump piston (28) in an axial direction promotes liftoff of the seal (46) from the pump cylinder (40) in a radially inward direction, in particular promoting it by virtue of the fact that a radially outer surface of the seal (46), which is situated opposite an inner surface of the pump cylinder (40), slopes radially inward at an angle α of 10° to 60° to the inner wall of the pump cylinder (40) in an axial end region (464) of the seal (46).
EP15805167.2A 2014-12-17 2015-12-04 Piston fuel pump for an internal combustion engine Active EP3234343B1 (en)

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DE102014226304.2A DE102014226304A1 (en) 2014-12-17 2014-12-17 Piston fuel pump for an internal combustion engine
PCT/EP2015/078694 WO2016096483A1 (en) 2014-12-17 2015-12-04 Piston fuel pump for an internal combustion engine

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EP (1) EP3234343B1 (en)
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DE102020214632A1 (en) * 2020-11-20 2022-05-25 Robert Bosch Gesellschaft mit beschränkter Haftung Piston pump, in particular high-pressure fuel pump for an internal combustion engine

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US10400727B2 (en) 2019-09-03
WO2016096483A1 (en) 2016-06-23
JP6472522B2 (en) 2019-02-20
EP3234343A1 (en) 2017-10-25
KR20170093854A (en) 2017-08-16
US20170306912A1 (en) 2017-10-26
DE102014226304A1 (en) 2016-06-23
CN107110096A (en) 2017-08-29
JP2017538891A (en) 2017-12-28

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