EP3077656B1 - Fuel pump - Google Patents

Description

The present invention relates to a fuel pump, comprising at least: a pump piston, a camshaft having at least one cam, a roller tappet arranged between the pump piston and the cam, which has a tappet body and a roller rotatably supported thereon, wherein the pump piston and the tappet body with respect Movements are coupled in directions parallel to the piston longitudinal center line, wherein the roller is in contact with the cam, wherein a geometric reference line which extends the piston longitudinal center line rectilinearly intersects the geometric axis of rotation of the roller, and wherein the plunger body has a ram body longitudinal center line parallel to the reference line ,

Such fuel pumps are used, for example, as high-pressure fuel pumps for fuel injection systems of internal combustion engines. The role of the roller tappet abuts the peripheral surface of the cam. The plunger is movably received in its tappet body in directions parallel to the tappet body longitudinal centerline in a tappet body guide. In operation, as the camshaft rotates about its geometric (i.e., imaginary linear) axis of rotation, the roller tappet is reciprocated in directions opposite and parallel to its tappet body longitudinal centerline. The geometric axis of rotation of the camshaft is the imaginary line around which the camshaft rotates exclusively.

As long as during the rotation of the cam, the distance between the contact zone roller / cam and the geometric axis of rotation of the camshaft decreases, the pump piston, usually supported by a compression spring, during the so-called. Suction phase withdrawn from the pumping chamber, causing a so-called. Suction stroke executes. On the other hand, during the rotation of the cam, the distance between the contact zone roller / cam and the increased geometric axis of rotation of the camshaft, the pump piston is moved by means of the plunger body during the so-called. Pressure phase with its one longitudinal end first in the cylinder chamber of the pump piston into it, where he performs a so-called. Compression. In each case at the transition from a suction phase to a printing phase, the roller is in the so-called. Bottom dead center, while it is at each transition from a pressure phase to a suction phase in the so-called. Top dead center. This principle of a so-called. Radial piston pump is known per se, wherein in such known fuel pumps, the plunger body longitudinal center line and the reference line lie on a common geometric straight lines.

Between the roller and the cam acts in the contact zone a line load, which depends inter alia on the pressure force exerted by means of a supported against the housing of the fuel pump compression spring on the roller tappet. The line load acting on the roller in the contact zone is not always constant over the length of the contact zone during operation, but may, for example, be unevenly distributed due to small form and / or positional deviations with respect to the center of the roller. Then results in the middle of the roll, ie the position at half the roll length related unbalanced force introduction into the role. This can cause a torque about a torque axis perpendicular to the geometric axis of rotation of the roller. In the case of fuel pumps known in the state of the art, an asymmetrical introduction of force via the roller contact, in particular when rolling over top dead center, but also when rolling over bottom dead center, may under certain circumstances cause the tappet body to rotate about its tappet body longitudinal center line if no rotation lock is provided. Rotation of the plunger body may block and eventually destroy the pump drive. In the prior art, in order to prevent twisting of the tappet body, attempts were made to avoid any asymmetrical introduction of force, in particular by limiting the manufacturing tolerances. But this means a lot of effort and high costs. Therefore, fuel pumps are known which, in order to prevent a rotation of the plunger body, possess positive locking against rotation. For example, the plunger body has a rectangular cross-section. It is also known that the plunger body has a round basic shape in cross-section, but at the outer edge of a radial projection is formed which forms a positive rotation with a recess in the housing-fixed plunger body guide. Again, this is considered to be disadvantageous in terms of design effort and cost.

JP 2013 096328 A discloses a fuel pump including a pump piston, a camshaft having a cam and an intermediate pumping piston, and cam-mounted roller tappets having a tappet body and a roller rotatably supported therein. The pump piston and the plunger body are motion-coupled with respect to movements in a direction parallel to a piston longitudinal centerline. The roller is in contact with the cams, with a geometric reference line that extends the piston longitudinal centerline in a straight line intersecting a geometric axis of rotation of the roller.

Against this background, the invention has the object, advantageously further develop a fuel pump of the type mentioned. In particular, it is desirable to counteract a rotation of the plunger body in a simple and inexpensive manner.

The object is achieved by the invention initially and essentially in conjunction with the features that the ram body longitudinal center line in a projection oriented parallel to the geometric axis of rotation of the roller projection view at a lateral distance from the geometric reference line. The invention proposes to offset in contrast to the prior art, the plunger body longitudinal center line and thus the, preferably circular, cross-sectional outer contour of the plunger body in or against the direction of rotation of the cam or the drive shaft (in the direction perpendicular to the reference line). Preferably, neither the roller nor the camshaft are added to the pump piston. It was found that in such a Basically changed position of the plunger body relative to the reference line of rotation of the plunger body counteracts a counter torque that can partially or even completely cancel the caused by an undesirable asymmetric external force introduction torque. If the ram body longitudinal center line is offset by a distance laterally from the reference line extending in the extension of the piston longitudinal centerline, a counterforce acting in parallel with the line of contact of the roller and the cam acts by means of a frictional connection at the contact line between roller and cam Distance between an opposing torque forms. This counteracts an undesirable torque generated by an external asymmetrical introduction of force, as a result of which rotation of the tappet body can be prevented.

In this way, the desired rotational position of the plunger body, in which the geometric axis of rotation of the roller and the geometric axis of rotation of the cam shaft parallel to each other, stabilized. As a result, rotation of the roller tappet from this desired rotational position can be prevented or at least made more difficult during operation in the upper and lower dead center of the roller. The invention is based on the fundamentally novel idea to replace the known positive rotation of the plunger body by a non-positive rotation. The invention advantageously makes it possible that manufacturing tolerances need not be unnecessarily restricted. Another advantage is seen in the fact that the cost of a geometric, positive rotation on the roller tappet can be omitted. For example, a cylindrical bore is sufficient as a longitudinal guide for the tappet body without additional, elaborate groove or other devices. It has also been found that the desired rotational position of the tappet body is stabilized in positions of the roller between the two dead centers by then acting on the roller at the contact zone to the cam a also directed transversely to the contact normal direction of line load.

There are numerous possibilities for the preferred development of a fuel pump according to the invention.

In a preferred embodiment it is provided that, at least at top dead center and in particular at bottom dead center of the roller in the said projection consideration, the contact zone between the cam and roller is laterally spaced from the ram body longitudinal centerline. At top dead center, the distance between the roller and the geometric axis of rotation of the camshaft is maximum. At bottom dead center, this distance is minimal. The contact zone comprises the geometric contact line between the roller and the cam and in particular a narrow zone of Hertzian pressure enclosing the geometric contact line. In a preferred embodiment, the so-called geometric reference line intersects the geometric axis of rotation of the camshaft. Appropriately (that is not necessary), the geometric axis of rotation of the roller is perpendicular to the reference line. Also preferably, the geometric axis of rotation of the camshaft is perpendicular to the reference line. The pump piston and the plunger body can be coupled in any desired manner, in particular by means of additional components of the fuel pump, in the directions parallel to the piston longitudinal center line and opposite to each other. As a result of the movement coupling, the pump piston and the tappet body execute synchronous movements parallel to the piston longitudinal center line.

There is a possibility that the slide body longitudinal center line in the projection view is on the side of the reference line which is in front of the reference line with respect to the circumferential direction of movement of the cam selected in the contact area of cam and roller for operation. In this case, in other words, the ram body longitudinal center line, starting from the reference line extending the piston longitudinal center line, is offset laterally against the direction of rotation of the roller and cam relative to its contact area. Alternatively, in the projection view, the ram body longitudinal centerline may be on the side of the datum line that is behind the datum line with respect to the circumferential direction of travel of the cam selected in the contact area of the cam and roller for operation.

Preferably, the fuel pump comprises a cylinder space into which the pump piston projects and relative to which the pump piston can be reciprocated in a direction parallel to the piston longitudinal center line when the camshaft is rotated by means of the roller tappet. It is considered appropriate that the pump piston in the cylinder chamber in this Directions is longitudinally displaceable. It is preferred that the plunger body is movably guided in directions parallel to the plunger body longitudinal center line in a plunger body guide. It is considered to be advantageous for a guide surface formed on the plunger to lie on or radially within an inner cylindrical envelope surface, that a guide surface of the plunger body guide formed in a recess of the plunger body guide lies on or radially outside an outer cylindrical envelope surface and that the diameter of the inner envelope surface is smaller than the diameter of the outer envelope surface. The cylindrical envelope surface of the guide surface of the ram is concentric with the ram body longitudinal centerline. It is preferred that the guide surface of the tappet body and / or that the guide surface of the tappet body guide extend at least in sections or as a whole cylindrically. As appropriate (ie, as not necessary), it is considered that the diameter of the inner envelope surface and the diameter of the outer envelope surface are matched to achieve a clearance fit or a transition fit between the tappet body and the tappet guide.

In a preferred embodiment, it is provided that the outer guide surface of the plunger and the inner guide surface of the plunger body guide each extend continuously cylindrical along its entire circumference around the plunger body longitudinal centerline. This allows a particularly simple production. The inwardly facing guide surface can be created by inserting a cylindrical bore in the plunger body. The outwardly facing guide surface can be made on the plunger body by means of simple turning.

It is preferred that the piston longitudinal center line rectilinearly extending reference line and the plunger body longitudinal centerline lie in a common geometric plane that extends perpendicular to the geometric axis of rotation of the camshaft.

In order to allow the pump piston and the plunger body to be rotationally coupled with respect to movements in directions parallel to the piston longitudinal center line, the preferred possibility is that the plunger body is supported by a compression spring against the housing of the fuel pump adjacent to a cylinder space cooperating with the pump piston and the pump piston in leading away from the cylinder chamber, is supported parallel to the piston longitudinal center line direction against the plunger body.

It is preferably contemplated that the fuel pump is a high-pressure fuel pump that is suitable and in particular adapted for this, fuel at a pressure of more than 100 bar, in particular at a pressure between 150 and 250 bar, or at a pressure of more than 1000 bar, in particular to compress pressure between 1500 and 2500 bar. For example, it may be a gasoline injection pump or a diesel injection pump for the engine of a motor vehicle. It is understood, however, that fuel pumps according to the invention can also be used for other purposes.

It is considered appropriate that the pump piston has an outer guide surface which forms a longitudinal guide with an inner guide surface of a pump piston guide in the direction of the piston longitudinal centerline. For easy and inexpensive manufacture, it is preferred that the outer guide surface of the pump piston and the inner guide surface of the pump piston guide extend concentrically and cylindrically about the piston longitudinal centerline along their respective entire circumference.

• Fig. 1: in einem Längsschnitt schematisch vereinfacht Komponenten und deren Anordnung bei einer bekannten Kraftstoffpumpe;
• Fig. 1a: in einer Schnittansicht entlang Schnittlinie Ia-Ia gemäß Fig. 1 eine erste bekannte formschlüssige Verdrehsicherung für den Stößelkörper;
• Fig. 1b: in einer Fig. 1a vergleichbaren Schnittansicht eine zu Figs. 1, 1a alternative zweite bekannte formschlüssige Verdrehsicherung für den Stößelkörper;
• Fig. 2: in einem Längsschnitt schematisch vereinfacht Komponenten und deren Anordnung bei einer erfindungsgemäßen Kraftstoffpumpe gemäß einem bevorzugten Ausführungsbeispiel;
• Fig. 2a: eine Schnittansicht entlang Schnittebene IIa-IIa gemäß Fig. 2, unter Fortlassung der Druckfeder und in von Fig. 2a abweichendem Maßstab;
• Fig. 2b: schematisch und im Vergleich zu Fig. 2a in etwas anderer Größe eine Draufsicht auf die Rolle mit einer an ihrer gestrichelt angedeuteten Kontaktlinie zu dem Nocken auf sie einwirkenden symmetrischen Streckenlast;
• Fig. 2c: schematisch und im Vergleich zu Fig. 2a in etwas anderer Größe eine Draufsicht auf die Rolle mit einer an ihrer gestrichelt angedeuteten Kontaktlinie zu dem Nocken auf sie einwirkenden unsymmetrischen Streckenlast und
• Fig. 2d: schematisch eine Draufsicht auf einen Längenabschnitt der Rolle mit die Rolle in ihrer Drehlage stabilisierender Gegenkraft und daraus resultierendem Gegendrehmoment.

Hereinafter, with reference to the attached Figures 1, 1a and 1b a known fuel pump and with reference to the attached Figures 2 . 2a, 2b, 2c and 2d an embodiment of a fuel pump according to the invention explained. In detail shows:

• Fig. 1 in a longitudinal section schematically simplified components and their arrangement in a known fuel pump;
• Fig. 1a in a sectional view along section line Ia-Ia according to Fig. 1 a first known positive locking rotation for the plunger body;
• Fig. 1b : in a Fig. 1a comparable sectional view one to Figs. 1, 1a alternative second known form-locking rotation for the ram body;
• Fig. 2 in a longitudinal section schematically simplified components and their arrangement in a fuel pump according to the invention according to a preferred embodiment;
• Fig. 2a FIG. 3: a sectional view along section plane IIa-IIa according to FIG Fig. 2 , omitting the compression spring and in from Fig. 2a different scale;
• Fig. 2b : schematic and compared to Fig. 2a in somewhat different size, a plan view of the roller with a symmetrical line load acting on it at its dashed line of contact with the cam;
• Fig. 2c : schematic and compared to Fig. 2a in somewhat different size a plan view of the role with an indicated at dashed lines line of contact with the cam acting on them unbalanced line load and
• Fig. 2d schematically a plan view of a longitudinal portion of the roller with the role in their rotational position stabilizing counterforce and the resulting counter torque.

First, with respect to the Figures 1, 1a and 1b to a known fuel pump 1 'components and their relative position to each other described. The fuel pump 1 'comprises a pump piston 2', whose longitudinal direction in the direction of the upper end 3 ' a cylinder room protrudes. A camshaft 4 'comprises a central shaft 5' and at least one cam 6 'rotatably mounted thereon (ie, not rotatable relative to the shaft 5'). The fuel pump 1 'comprises a roller tappet 7'. This has a plunger body 8 'and a manner not shown in detail about a central geometric (ie imaginary linear) axis of rotation 11' rotatably supported roller 9 'on. The roller tappet 7 'is arranged between the pump piston 2' and the cam 6 '. The roller tappet 7 'is connected to the pump piston 2' on in FIG. 1 not shown manner coupled so that both components parallel to the piston longitudinal centerline 10 'perform the same movements. The roller 9 'rolls on an outer edge 12' of the cam 6 'from. Through the pump piston 2 'in the longitudinal direction centrally a piston longitudinal center line 10'. The plunger body 8 'extends along a central plunger body longitudinal center line 13' that is central to it. In the known fuel pump 1 ', the plunger body longitudinal centerline 13' is located on a geometric reference line 20 'which extends the piston longitudinal centerline 10' in a straight line. In the known fuel pump 1 'thus extend the piston longitudinal centerline 10' and the plunger body longitudinal centerline 13 'on a common line. The plunger body 8 'is in parallel to the plunger body longitudinal centerline 13' parallel directions, ie in FIG. 1 up and down, movably received in a tappet body guide 14 '. This may be part of a housing 15 'of the fuel pump 1'. In order to prevent unwanted rotation of the plunger body 8 'about its ram body longitudinal center line 13', the plunger body 8 'and the plunger body guide 14' together form a positive rotation about the ram body longitudinal centerline 13 'from. In the example of Figures 1 and 1a For this purpose, the plunger body 8 ', which otherwise has a radial projection 16' on its outer cross-section, extends into a groove 17 'in the plunger body guide 14' extending parallel to the plunger body longitudinal center line 13 'with respect to the assumed direction of rotation of the roller 9', designated by 18 '. rotationally locking engages. The 18 'matching direction of rotation of the cam 6' is denoted by 19 '. FIG. 1b shows a known in the prior art variant FIG. 1a , A Positive rotation is formed there by the fact that in the plunger body guide 14 'radially inwardly projecting pin 21' in a parallel to the longitudinal direction Plunger body longitudinal line 13 'extending groove 22' in the plunger body 8 'protrudes.

With reference to the FIGS. 2 to 2d is schematically simplified a preferred embodiment of a fuel pump 1 according to the invention presented. For a better overview are for components that from those FIGS. 1 to 1b numerically the same reference numerals are chosen, but in order to distinguish the in the FIGS. 1 to 1b the numbers trailing the numbers (') in the FIGS. 2 to 2d eliminated.

The fuel pump 1 comprises a pump piston 2, the upper end 3 of which projects in the direction of the direction into a cylinder space 23. The boundary wall 24 of the cylinder chamber 23 may be, for example, part of the housing 15 of the fuel pump 1 or be firmly connected to the housing 15. In the vicinity of the front end opens into the cylinder chamber 23 a fluidically connected to a fuel tank 25 inlet line 26 for fuel, in which an intake valve 27 is arranged as an inlet valve. This is open when the pressure in the cylinder chamber 23 during the suction phases, the pressure in the fuel tank 25 by a certain pressure difference below. Also in the vicinity of the front end of the cylinder chamber 23 is an outlet 28 of which, for example, to a (in FIG. 2 not shown) high-pressure accumulator an injection system for an internal combustion engine leads. In the outlet line 28, a pressure valve 29 is arranged as an outlet valve. This is open during pressure phases when the fuel pressure in the cylinder chamber 23 exceeds a certain pressure.

The fuel pump has a camshaft 4, which has a central shaft 5 and at least the one, in FIG. 2 shown, rotatably on it (ie, not rotatable relative to the shaft 5) mounted cam 6 has. The fuel pump 1 comprises a roller tappet 7. This has a plunger body 8 and a manner not shown in detail about a central geometric (ie imaginary linear) axis of rotation 11 rotatably held roller 9. The plunger body 8 has on its side facing away from the pump piston 2, that is in the view of FIG. 1 lower, side a recess 30 for captive and thereby about its cross-sectional center or about its geometric axis of rotation 11 rotatable recording of the roller 9. The recess 30 has a radially inwardly facing bearing surface 31, which in the in FIG. 1 visible cross section along a circular contour, namely, to prevent falling out of the roller 9 down, extends along a circumferential angle of more than 180 degrees. The diameter of said circular contour is slightly larger than the outer diameter of the roller 9, so that the roller 9 is rotatably supported. In the example, the diameters are chosen so that a lower, in FIG. 2 simplified only shown as a simple line gap 32 results, penetrates into the fuel during operation and one, in particular hydrodynamic, lubrication or sliding bearing of the roller 9 causes.

The roller tappet 7 is arranged between the pump piston 2 and the cam 6. The roller tappet 7 is rotationally coupled to the pump piston 2 so that both components perform synchronous (thus, equal) movements with respect to the two directions (back and forth) parallel to the piston longitudinal centerline 10. The pump piston is also in the cutting plane of FIG. 2 , but is shown without hatching. In the exemplary embodiment shown, the plunger body 8 is supported against a compression spring 33 in the direction parallel to the plunger body longitudinal center line away from the cam 5. This is supported in the same direction against the cylinder chamber 23 adjacent housing 15 of the fuel pump 1. The compression spring 33 is dimensioned so that it is in any possible position of the plunger body 8 under a spring pressure force and thus pushes the plunger body 8 in the direction of the cam 6. In the example, the plunger body 8 is supported by means of a spring plate 34 on the compression spring 33. The spring plate 34 is disposed between the compression spring 33 and a front bottom of a bore 35 formed in the plunger body 8. He engages with the inner edge of its central opening axially positive fit in a groove 36 in the pump piston 2, so that a positive connection results for both mutually opposite, parallel to a piston longitudinal center line 10 axial directions.

The roller 9 rolls on an outer edge 12 of the cam 6 from. The piston longitudinal center line 10 extends centrally through the pump piston 2. The plunger body 8 extends along its central longitudinal body center line 13 plunger body. He is in parallel to the ram body longitudinal centerline 13 'parallel directions, ie in FIG. 2 up and down, movably received in a tappet body guide 14. This is in FIG. 2 shown only partially and in the example also part of the housing 15 of the fuel pump 1, in which the cylinder chamber 23 is formed.

FIG. 2 shows a geometric or imaginary reference line 20, which extends the piston longitudinal center line 10 in a straight line to the cam 6 and which intersects the geometric axis of rotation 11 of the roller 9. In the chosen Ausführungs¬ example, the reference line 20 also intersects the geometric axis of rotation 38 of the cam 6. In the example, it is provided that the ram body longitudinal center line 13 and the reference line 20 in a common, the drawing plane of FIG. 2 corresponding and perpendicular to the geometric axis of rotation 38 of the camshaft 4 geometric plane lie (see. FIG. 2a ). This corresponds to the desired non-rotated orientation of the roller tappet 7. The plane in which the ram body longitudinal center line 13 and the reference line 20 lie, is also perpendicular to the geometric axis of rotation 11 of the roller. 9

In contrast to the known fuel pump 1 'runs in the inventive fuel pump 1, the plunger body longitudinal center line 13 at a lateral distance a from the geometric reference line 20. Such consideration with respect to a lateral distance in the sense of claim 1 would also be possible if the plunger body longitudinal center line thirteenth (deviating from the one in FIG. 2 and 2a shown example) is outside of the geometric axis of rotation 38 of the camshaft 4 perpendicular and leading through the reference line 20 level. Be there the ram body longitudinal center line 13 different from that in the Figures 2 and 2a example shown, for example, positionally starting from the in FIG. 2 shown position behind the plane of FIG. 2 shifted, would result in a parallel to one of the axis of rotation 38, ie in the direction of FIG. 2 , projection oriented projection in turn that the ram body longitudinal center line 13 at a lateral distance a from the geometric reference line 20 extends. In such projection viewing, the two lines 13 and 20 are projected into a common viewing plane. At the in FIG. 2 In the embodiment shown, it is provided that the ram body longitudinal center line 13 in the projection view lies on that side of the reference line 20 which is relative to the circumferential direction of movement selected in the contact zone 37 of cams 6 and 9 for operation FIG. 2 at the same time indicated by the direction of rotation arrow 19) of the cam 6 in front of the reference line 20.

In the embodiment shown, the plunger body 8 on the outside has a guide surface 41, which extends generally cylindrical. In the region of the housing 15 of the fuel pump 1 which forms the tappet body guide 14, there is a bore 43 whose radially inwardly facing surface forms a guide surface 42 of the tappet body guide 14. The guide surface 42 is also generally cylindrical. Consequently, the plunger body 8 and the plunger body guide 14 do not form a positive connection with each other in the rotational direction about the plunger body longitudinal center line 13. The pump piston 2 and formed to its longitudinally displaceable guide in the housing 15 pump piston guide (in the example is the wall of the cylinder chamber 23) each have cylindrical guide surfaces, so that the pump piston 2 and the housing 15 no positive connection in the direction of rotation around the piston longitudinal centerline 10.

The FIGS. 2b and 2c show schematically and in comparison to Fig. 2a in a slightly different size, a respective plan view of the roller 9, in an imaginary operating condition, in which the Roller 9 abuts against the cam 6 in the edge region of its greatest eccentricity with respect to the geometric axis of rotation 38 of the camshaft 4. This situation is also called top dead center. The FIGS. 2a and 2b indicate schematically comparative exemplary two different distributions of the force acting on the roller 9 in the contact zone to the cam 6 line load along the length of the contact zone 37 at. In the example of FIG. 2b acts along the contact zone with respect to the roller center 39 of the roller 9 symmetrical line load 40. At a symmetrical line load 40 causes this in the two dead centers of the roller 9 no rotation of the plunger body 8. Deviating shows Figure 2c If these are replaced on each side of the roller center 39 by a resultant force F1 or F2, they show parallel spaced in the same direction, but are, as schematically indicated by the unequal arrow lengths of different amount. The unequal forces F1 and F2 present as a result of an asymmetrical force application each act with a lever arm of equal length around the roller center 39, so that the in Figure 2d schematically registered torque M12 results around the ram body longitudinal center line 13. The torque M12 could cause undesirable rotation of the plunger body 8 about the plunger body longitudinal centerline 13 without countermeasure at the top and bottom dead centers of the roller 9. As Figure 2d shows, according to the lateral distance a between the reference line 20 and the plunger body longitudinal center line 13 in the fuel pump 1 according to the invention an oriented in the arrow direction of M12 rotation of the roller 9 but cause a counter to the torque M12 counter torque M3. The simplified graphic in Figure 2d shows that in this case a caused by the frictional connection at the line contact of the contact zone 37 counterforce F3 acts with a lever arm of the length of the lateral distance a to the ram, Körperlängsmittellinie 13, whereby the counter torque M3 results. This acts in opposite to the torque M12 rotation about the ram body longitudinal center line 13, so that both torques proportionately or even completely compensate, whereby the roller 9 and the plunger body. 8 be stabilized in a desired orientation in which the axes of rotation of the cam 6 and the roller 9 are parallel. LIST OF REFERENCE NUMBERS 1, 1 ' Fuel pump 25 Fuel tank 2, 2 ' pump pistons 26 inlet line 3, 3 ' longitudinal end 27 intake valve 4, 4 ' camshaft 28 outlet pipe 5, 5 ' wave 29 pressure valve 6, 6 ' cam 30 recess 7, 7 ' roller plunger 31 bearing surface 8, 8 ' tappet body 32 gap 9, 9 ' role 33 compression spring 10, 10 ' Piston longitudinal center line 34 spring plate 11, 11 ' geometric axis of rotation 35 drilling 12, 12 ' outer edge 36 groove 13, 13 ' Tappet body longitudinal center line 37 contact zone 14, 14 ' Tappet body guide 38 geometric axis of rotation 15, 15 ' casing 39 role center 16 ' head Start 40 line load 17 ' groove 41 guide surface 18, 18 ' direction of rotation 42 guide surface 19, 19 ' direction of rotation 43 drilling 20, 20 ' geometric reference line a lateral distance 21 ' spigot F ₁ force 22 ' groove F ₂ force 23 cylinder space F ₃ counterforce 24 boundary wall M ₁₂ torque M ₃ counter torque

Claims (10)

1. Fuel pump (1), at least comprising: a pump piston (2), a camshaft (4) which has at least one cam (6), a roller tappet (7) which is arranged between the pump piston (2) and the cam (6) and which has a tappet body (8) and a roller (9) rotatably held thereon, wherein the pump piston (2) and the tappet body (8) are movement-coupled with regard to movements in directions parallel to the piston longitudinal centerline (10), wherein the roller (9) is in contact with the cam (6), wherein a geometric reference line (20) which forms a rectilinear elongation of the piston longitudinal centerline (10) intersects the geometric axis of rotation (11) of the roller (9), and wherein the tappet body (8) has a tappet body longitudinal centerline (13) which is parallel to the reference line (20), characterized in that the tappet body longitudinal centerline (13), in a projected view oriented parallel to the geometric axis of rotation (11) of the roller (9), runs with a lateral spacing (a) to the geometric reference line (20).
2. Fuel pump (1) according to Claim 1, characterized in that, at least at top dead center and in particular at bottom dead center of the roller (9), in the projected view, the contact zone (37) between cam (6) and roller (9) is situated so as to be laterally spaced apart from the tappet body longitudinal centerline (13).
3. Fuel pump (1) according to one of the preceding claims, characterized in that the geometric reference line (20) intersects the geometric axis of rotation (38) of the camshaft (4) .
4. Fuel pump (1) according to one of the preceding claims, characterized in that, in the projected view, the tappet body longitudinal centerline (13) is situated on that side of the reference line (20) which, with regard to the direction of circumferential movement of the cam (6), selected for operation, in the contact zone of cam (6) and roller (9), is situated in front of the reference line (20) or which, with regard to the direction of circumferential movement of the cam (6), selected for operation, in the contact zone of cam (6) and roller (9), is situated behind the reference line (20).
5. Fuel pump (1) according to one of the preceding claims, characterized in that the tappet body (8) is guided in a tappet body guide (14) so as to be movable in directions parallel to the tappet body longitudinal centerline (13), in that a guide surface (41) of the tappet body (8) lies on or within an inner cylindrical envelope, in that a guide surface (42) of the tappet body guide (14) lies on or outside an outer cylindrical envelope, and in that the diameter of the inner envelope is smaller than the diameter of the outer envelope.
6. Fuel pump (1) according to Claim 5, characterized in that the outer guide surface (41) of the tappet body (8) and the inner guide surface (42) of the tappet body guide (14) run in each case in continuously cylindrical fashion along their entire respective circumference around the tappet body longitudinal centerline (13).
7. Fuel pump (1) according to one of the preceding claims, characterized in that the reference line (20) and the tappet body longitudinal centerline (13) lie in a common geometrical plane which extends perpendicular to the geometric axis of rotation (38) of the camshaft (4).
8. Fuel pump (1) according to one of the preceding claims, characterized in that the tappet body (8) is supported by way of a compression spring (33) against that region of the housing (15) of the fuel pump (1) which is adjacent to a cylinder chamber (23) which interacts with the pump piston (2), and/or in that the pump piston (2) is supported against the tappet body (8) in a direction which leads away from the cylinder chamber (23) and which is parallel to the piston longitudinal centerline (10).
9. Fuel pump (1) according to one of the preceding claims, characterized in that the fuel pump (1) is a high-pressure fuel pump which is suitable, and in particular designed, for compressing fuel to a pressure of over 100 bar, in particular to a pressure of between 150 and 250 bar, or to a pressure of over 1000 bar, in particular to a pressure of between 1500 and 2500 bar.
10. Fuel pump (1) according to one of the preceding claims, characterized in that the pump piston (2) has an outer guide surface which, with an inner guide surface of a pump piston guide, forms a longitudinal guide in the direction of the piston longitudinal centerline (10), and in that the outer guide surface of the pump piston (2) and the inner guide surface of the pump piston guide run, along their entire respective circumference, concentrically and cylindrically around the piston longitudinal centerline (10).

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