Method for producing a roller tappet for a pump or valve train of an internal combustion engine

Abstract

The invention relates to a method for producing a roller tappet (44) for a pump or valve train of an internal combustion engine, comprising a cylindrical housing (43) which serves to guide the roller tappet (44) in a longitudinally movable manner in a bore in an internal combustion engine, characterized in that the housing (43) is produced as a cylindrical shell component (1) with at least one flattened portion (5, 6, 7, 8) on the outer diameter in a lightweight construction, and at least one edge (11 to 18) formed by the flattened portion (5, 6, 7, 8) in a central region on the outer diameter of the shell component (1) located between the axial ends of the shell component (1) is deburred by turning with low notch effect. The invention further relates to a forming tool (31, 34, 36) for producing a roller tappet (44) using such a method. The invention further relates to a roller tappet (44) which is produced in such a method in a lightweight construction.

Description

[0001] The invention relates to a method for producing a roller tappet for a pump or valve train of an internal combustion engine. The invention further relates to a mold for producing a roller tappet using such a method. The invention further relates to a roller tappet produced using such a method.

[0002] From DE 10 2017 107 100 B3 a multi-part roller tappet for a high-pressure fuel pump is known, which is guided in a housing receptacle in the direction of its longitudinal axis and is driven by cams of a camshaft so as to be displaceable in the longitudinal direction.

[0003] The invention is therefore based on the object of proposing a method, a molding tool and a roller tappet of the aforementioned type which enable simple and cost-effective production and ensure safe and efficient operation of the internal combustion engine.

[0004] The object is achieved by the features of claim 1 and alternatively by the features of claims 8 or 10. Further advantageous and claimed embodiments emerge from the respective subclaims, the description, and the drawings.

[0005] Thus, a method for producing a roller tappet for a pump or valve train of an internal combustion engine is proposed, comprising a housing that serves to movably guide the roller tappet in a bore in the internal combustion engine. The housing of the roller tappet is manufactured as a cylindrical, lightweight component with at least one flattened portion on the outer diameter, and at least one edge formed by the flattened portion in a central region located between the axial ends of the component on the outer diameter of the housing is deburred by turning with minimal stress on the notch.

[0006] As a result, the roller tappet with a reduced-mass, lightweight housing is easy to manufacture, increasing dynamics and efficiency during operation. Turning allows the sharp edges created during manufacturing in the aforementioned central area of ​​the outer diameter of the housing to be deburred quickly, easily, and cost-effectively, without creating sharp notches on the outer diameter of the non-flattened areas, which would impair the strength of the housing.

[0007] During operation, scraping of material in the bore for the ram guide caused by transverse forces caused by sharp edges on the housing and the resulting operational disruptions, in particular by chips being pushed up in the bore, can be reliably avoided and low-friction, efficient and safe operation can be ensured.

[0008] For low-stress deburring, a slightly concave curve is preferably created by turning on one or more edges. The rounded shape ensures a low-stress design on the outer diameter, particularly in the non-flattened areas of the housing, for example as a groove with a rounded cross-sectional profile and a shallow penetration depth on the outer diameter of the housing. Other low-stress deburring shapes with a continuous course and no abrupt change in direction are also conceivable, such as an arc, particularly a circular arc or an elliptical shape. In this way, one or more edges can be deburred by turning without weakening the component strength in the non-flattened areas of the raw component.

[0009] In a particularly preferred embodiment of the invention, one or more flattened portions are produced, each with a rectangular shape in a radial plan view, with two edges perpendicular to the cylinder axis of the blank, thus in the circumferential direction of the blank, and with two edges parallel to the cylinder axis on the outer diameter of the blank. This allows the respective flattened portion to be produced with two edges parallel to the longitudinal axis of the blank, i.e., in the direction of movement of the roller tappet during operation, so that they do not require deburring.

[0010] Preferably, the flats are produced with the longer edges perpendicular to the cylindrical axis of the blank in the radial plan view, and with the shorter edges parallel to it. This allows the longer longitudinal edges to be easily deburred by turning. Preferably, one or more flats are each produced by milling.

[0011] The lightweight construction of the roller tappet can be further improved if, in a next preferred embodiment of the invention, the shell component is manufactured with a plurality of arranged flattened portions.

[0012] Preferably, the raw component is manufactured with at least two axially and at least two circumferentially aligned flats arranged one behind the other. Several circumferential edges formed on the outer diameter in the central axial region by the production of the flats are deburred by turning in a single operation.

[0013] Preferably, the flattened portions are offset by 180° in the circumferential direction. This allows the raw component to be produced particularly cost-effectively with thin walls by extrusion.

[0014] Preferably, the shell is extruded hollow with a receptacle extending from one axial end, which is elongated in plan view, for accommodating a cam roller. The wall thickness of the shell on the longitudinal sides of the receptacle is greater than the wall thickness on the end faces of the receptacle. In this way, a material accumulation is achieved in the areas of greater wall thickness, ensuring good extrusion properties during the shell's production.

[0015] In this case, the flattenings are preferably applied in the respective area of ​​the larger wall thickness on the outer diameter of the raw component in such a way that the raw component is manufactured with thin walls.

[0016] Preferably, two flattenings are produced, each starting from the axial end of the raw component on the outer diameter, which serves to accommodate the cam roller in the holder.

[0017] The proposed method can also be used to manufacture a bucket tappet for a pump or valve train of an internal combustion engine. The roller tappet or bucket tappet produced by the proposed method is particularly advantageous for use in passenger cars or trucks.

[0018] The object of the invention is also achieved by a forming tool for producing a roller tappet for a pump or valve train of an internal combustion engine using a method as described above. In this case, the tool cutting edge has a shaped profile with at least one convex rounding for low-notch deburring by turning at least one edge produced on the outer diameter of the blank. This results in the advantages already described above.

[0019] The tool cutting edge preferably has a shaped profile with several convexly curved rounded edges for simultaneous, low-notch deburring of several edges by turning. This allows several edges to be deburred in a single work step with low notch impact.

[0020] Within the scope of a further aspect of the present invention, a roller tappet for a pump or valve train of an internal combustion engine is proposed, which is manufactured using the method described above in a lightweight construction. This results in the advantages already described above.

[0021] Further claimed features of the invention will become apparent from the following description and the drawings, which further explain the present invention. They show: Fig. 1 shows a perspective view of the housing of a roller tappet for a pump drive of an internal combustion engine, manufactured as a shell component in a method according to the invention, in a first manufacturing state, Fig. 2 the shell component at one axial end in an axial plan view, Fig. 3 the shell in a longitudinal section, Fig. 4 the shell component is rotated by 180° around its longitudinal axis in a longitudinal section, Fig. 5 the shell component in a second manufacturing state in a perspective view, Fig. 6 the shell from Fig. 5 at one axial end in an axial plan view, Fig. 7 the shell from Fig. 5 in engagement with a deburring forming tool according to the invention in a first embodiment, Fig. 8 the shell from Fig. 7 after deburring in a longitudinal section, Fig. 9 an enlarged section of Fig. 8 Fig. 10 the shell from Fig. 8 in a longitudinal section rotated by 180° around the longitudinal axis, Fig. 11 and Fig. 12 a perspective partial view of the shell component, Fig. 13 a perspective view of the raw component in engagement with the molding tool according to the invention for deburring from Fig. 7, Fig. 14 a perspective view of the raw component in engagement with a molding tool according to the invention for deburring in a second embodiment, Fig. 15 a perspective view of the raw component in engagement with a molding tool according to the invention for deburring in a third embodiment, Fig. 16 a schematic representation of the sequence of stages of the method according to the invention, Fig. 17 a roller tappet according to the invention in a side view, Fig. 18 the roller tappet according to the invention in a side view rotated by 180° around the longitudinal axis, Fig. 19 the roller tappet according to the invention in a perspective view.

[0022] The figures illustrate various manufacturing stages of a roller tappet for a pump drive of an internal combustion engine, produced using a method according to the invention. These illustrations also illustrate the molding tool and roller tappet according to the invention.

[0023] Fig. 1 to 4 show the shell 1 of the roller tappet housing to be produced, produced by extrusion in the inventive method as an elongated cylindrical shell, in a first manufacturing state. The housing serves to guide the roller tappet longitudinally along an imaginary cylindrical or longitudinal axis 2 thereof in a tappet guide (not shown), in particular a bore, in a stationary component in an internal combustion engine. The cylindrical or longitudinal axis 2 simultaneously forms the center axis of the shell 1.

[0024] Starting from a drive-side axial end, the shell 1 is designed with a slot-shaped receptacle 3 in an axial plan view for arranging a cam roller (not shown) in the housing to be produced. The cam roller serves to pick up a cam stroke movement of the roller tappet from a camshaft (not shown) of the internal combustion engine ( Fig. 1 and Fig. 2).

[0025] The shell component 1 comprises a rod-shaped pump contact 4 which is arranged centrally and radially inwardly and which projects axially at the output end for transmitting a stroke movement, in particular to a high-pressure pump piston (not shown) in a pump drive ( Fig. 3 and Fig. 4).

[0026] The slot-shaped receptacle 3 has two parallel longitudinal sides and is curved at the narrow end faces. On the shell 1, the wall thickness S on the opposite longitudinal sides of the slot-shaped receptacle 3 is greater than the wall thickness s on the end faces of the receptacle 3. This creates a material accumulation on the longitudinal sides of the receptacle 3, which, in addition to the receptacle 3 for the cam roller, ensures good extrusion properties for the outer ring area.

[0027] In the Fig. In the second manufacturing state illustrated in Figures 5 to 8, four flattened portions 5, 6 and 7, 8 are preferably produced, preferably by milling, in the areas of greater wall thickness S on the outer diameter of the raw component 1 to reduce its mass. These flattened portions are arranged in two rows, each with two flattened portions 5, 6 and 7, 8 arranged axially one behind the other in alignment. In each row, these flattened portions are arranged axially spaced from one another by a cylindrical intermediate portion 27 and 28, respectively, which protrudes radially in a web-like manner axially between the flattened portions 5, 6 and 7, 8, respectively.

[0028] The two rows of flats 5, 6 and 7, 8 are arranged diametrically opposite each other, corresponding to the areas of greater wall thickness S on the outer diameter of the shell 1, offset by 180° in the circumferential direction. In the circumferential direction, the flats 5, 7 and 6, 8 are arranged in alignment one behind the other. In this way, the shell 1 is produced essentially thin-walled with reduced mass in a lightweight construction by extrusion ( Fig. 8 and Fig. 10). Wall thicknesses of 1 to 1.5 mm are preferably achieved.

[0029] A first flattening 5 or 7 of each row is produced starting from the drive-side axial end of the raw component 1, which serves to accommodate the cam roller in the receptacle 3. In the area of ​​the first flattenings 5 ​​or 7, aligned through holes 9, 10 are formed to accommodate a cam roller pin on which the cam roller is rotatably mounted.

[0030] The flattenings 5, 6, 7, 8 each have a rectangular shape in radial plan view. They form on the outer diameter of the shell part 1 two edges 11, 12 or 13, 14 and 15, 16 or 17, 18 running perpendicular to the cylinder axis 2 of the shell part 1 in the circumferential direction and two edges 19, 20 or 21, 22 and 23, 24 or 25, 26 running parallel to the cylinder axis 2. The flattened portions 5, 6, 7, 8 are aligned with the longer edges 11, 12 or 13, 14 and 15, 16 or 17, 18 in the circumferential direction and with the shorter edges 19, 20 or 21, 22 and 23, 24 or 25, 26 parallel to the cylinder axis 2.

[0031] The burr created during the production of the flattened portions 5, 6, 7, 8 on the longitudinal edges 11, 12 or 13, 14 and 15, 16 or 17, 18, which run perpendicular to the cylinder axis 2 of the blank 1 and thus transverse to its direction of movement during operation, must be removed, as this can cause damage to the guide bore for the ram guide due to material scraping and malfunctions due to the accumulation of chips. The longitudinal edges 11, 15 and 12, 16 and 13, 17, as well as 14, 18, which are located one behind the other in the circumferential direction, are each deburred simultaneously by simply turning.

[0032] The shorter edges 19, 20 or 21, 22 and 23, 24 or 25, 26 created during the production of the flattened portions 5, 6, 7, 8 each run parallel to the direction of movement of the roller tappet during operation, so that they do not need to be deburred.

[0033] The circumferential edges 12, 13, 14 and 16, 17, 18 of the respective flattened portions 5, 6, 7, 8 located between the axial ends in a central region of the shell 1 must be deburred with minimal notch effect to prevent weakening of the non-flattened cylindrical portions due to notch effect when deburring the flattened portions by turning. The edge 11 located at the drive-side end of the shell 1 and the edge located at the output-side end can be deburred simply, for example, by means of a chamfer as shown, since there is no risk of notch effect there.

[0034] After Fig. 7 to 9, a slightly concave, preferably circular-arc-shaped rounding 29 is produced by turning on the edges 12 to 18 for deburring. The rounded shape ensures a low-notch design on the outer diameter, particularly on the non-flattened areas of the raw component 1, preferably as a groove 30 indicated by dashed lines with a concave, rounded cross-sectional profile and a low penetration depth on the outer diameter of the raw component 1, as in the Fig. 10 to 15. Other shapes for deburring that exhibit a continuous course and no abrupt change in direction and have a low notch effect are also conceivable, such as a non-circular arc with variable curvature, particularly in the form of an ellipse.

[0035] In Fig. 7 and 13 to 15 show various designs of forming tools 31, 34, 36, each designed as a turning tool, in engagement with the raw component 1 for deburring by turning with low notch effect.

[0036] The Fig. 7 and Fig. The forming tool 31 shown in Figure 13 in a first exemplary embodiment has a tool cutting edge 32 with a shaped profile for the simultaneous deburring of all edges 12, 13, 14 and 16, 17, 18 located in the central region in a single work step. For this purpose, the shaped profile is designed with three convex curves 33, which correspond as a negative to the low-notch deburring shape to be produced on the edges 12, 13, 14 and 16, 17, 18. In this way, the forming tool 31 forms a profile plate tool that only needs to be applied once for the low-notch deburring of all six edges 12, 13, 14 and 16, 17, 18 running in the circumferential direction in the central axial region of the raw component 1.

[0037] In a second embodiment, the molding tool 34 has Fig. 14 has a tool cutting edge 35 with a shaped profile with two convex curves 33, which corresponds as a negative to the shape to be produced at the edges 12, 13 and 16, 17 in the intermediate regions 27, 28 for low-notch deburring. With this double forming tool 35, the four edges formed at the intermediate regions 27, 28 can be deburred in a single step with low-notch deburring.

[0038] In a third embodiment according to Fig. 15 shows a single-forming tool 36 having a tool cutting edge 37 with a convex rounding 33 for deburring. Accordingly, with the single-forming tool 36, one of the edges 12, 13, 14 and 16, 17, 18 can be deburred with minimal notch effect by applying it once.

[0039] Fig. Figure 16 schematically shows the sequence of stages during the production of the proposed roller tappet. In a first stage, the raw component 1 of the roller tappet housing to be produced is preferably cold extruded ( Fig. 1 to 4). Machining then takes place on the raw component 1. This includes, in particular, the production of the flats 5 to 8 by milling and the production of the through holes 9, 10 for receiving the cam roller bolt by drilling, as well as turning to deburr the edges 12, 13, 14 and 16, 17, 18, ( Fig. 5 to 13). In a third stage, an anti-twist opening 38 is punched out on the shell component 1 to accommodate an anti-twist element 39 ( Fig. 17 and Fig. 18). This is followed by heat treatment for hardening and fine grinding of the raw component 1. In a final stage, the cam roller 40 is mounted in the holder 3 and the cam roller bolt 41 is mounted in the through holes 9, 10 on the finished housing 42 ( Fig. 17 to 19). The proposed roller tappet is thus completely manufactured according to the process described above and is ready for use in the internal combustion engine.

[0040] In the Fig.Figures 17 to 19 show the roller tappet 44 manufactured according to the proposed method. The elongated cylindrical housing 42 of the roller tappet 44 serves to guide the roller tappet on its outer diameter along the longitudinal axis 2 in a bore of the internal combustion engine. At the drive-side end of the housing 42, the cam roller 41 is arranged in the receptacle 3 in the housing 42, rotatably mounted on the cam roller pin 41. The cam roller 41 protrudes slightly from the housing 42 for cam contact with the camshaft. At the output-side end of the housing 42, the pump contact 4, which is designed as a single piece with the housing, protrudes centrally. The housing 42 is significantly reduced in mass due to the four flattened areas 5 to 8 on the outer diameter and at the same time has a thin-walled, lightweight construction. The lightweight construction increases the dynamics of the roller tappet during operation.The housing 42 is completely cylindrical at the output-side end section 43 and at the intermediate region 27, 28 on the outer circumference. The circumferential edges 12 to 18 created by the manufacture of the flattened portions 5 to 8 on the outer diameter of the housing 42 are deburred by turning concave roundings 29 to minimize stress concentrations and each form a low-stress groove 30 with a rounded cross-sectional profile and shallow penetration depth on the cylindrical outer circumference of the housing 42. The anti-twist element 39 arranged in the anti-twist opening 38 on the shell 1 serves to secure the roller tappet against rotation during operation in the bore (not shown) for tappet guidance in the internal combustion engine. List of reference symbols 1 shell component 2 cylinder axis, longitudinal axis 3 Recording 4 Pump contact 5 Flattening 6 Flattening 7 Flattening 8 Flattening 9 Through hole 10 through hole 11 circumferential edge, longer edge 12 circumferential edge, longer edge 13 circumferential edge, longer edge 14 circumferential edge, longer edge 15 circumferential edge, longer edge 16 circumferential edge, longer edge 17 circumferential edge, longer edge 18 circumferential edge, longer edge 19 axial edge, shorter edge 20 axial edge, shorter edge 21 axial edge, shorter edge 22 axial edge, shorter edge 23 axial edge, shorter edge 24 axial edge, shorter edge 25 axial edge, shorter edge 26 axial edge, shorter edge 27 Intermediate area 28 Intermediate area 29 Deburring, concave rounding 30 grooves 31 Forming tool, turning tool 32 tool cutting edge 33 convex curve 34 Forming tool, turning tool 35 tool cutting edge 36 Forming tool, turning tool 37 Tool cutting edge 38 Anti-twist opening 39 Anti-rotation element 40 cam roller 41 cam roller bolts 42 housings 43 final section 44 roller tappets S wall thickness s wall thickness QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 107 100 B3

[0002]

Claims

[1] Method for manufacturing a roller tappet (44) for a pump or valve train of an internal combustion engine, comprising a cylindrical housing (42) which serves to guide the roller tappet (44) longitudinally in a bore in an internal combustion engine, characterized by , that the housing (42) is manufactured as a cylindrical raw component (1) with at least one flattening (5, 6, 7, 8) on the outer diameter in a lightweight construction and that at least one edge (11 to 18) formed by the flattening (5, 6, 7, 8) in a central area located between the axial ends of the raw component (1) on the outer diameter of the raw component (1) is deburred by turning with minimal notch effect. [2] Method according to claim 1, characterized by , that for deburring with low notch effect on one or more edges (11 to 18) a slightly concave curved rounding (29) is produced by turning. [3] Method according to one of claims 1 or 2, characterized by, that one or more flattened surfaces (5, 6, 7, 8) are each produced in a radial top view in a rectangular shape with two edges (11 to 18) perpendicular to the cylinder axis (2) of the raw component (1) extending in the circumferential direction and two edges (19 to 26) extending parallel to the cylinder axis (2). [4] Method according to any one of claims 1 to 3, characterized by , that the raw component (1) is manufactured with at least two axially and at least two circumferentially aligned flattened surfaces (5, 6, 7, 8) on the outer diameter and the circumferentially extending edges (12 to 18) formed on these are deburred in one operation by turning. [5] Method according to claim 4, characterized by , that the flattened surfaces (5, 7 and 6, 8) are produced offset from each other by 180° in the circumferential direction. [6] Method according to any one of claims 1 to 5, characterized by, that the raw component (1) is hollow with a recess (3) extending from an axial end and having an elongated hole-shaped receptacle in plan view for the arrangement of a cam roller (41), such that the wall thickness (S) on the longitudinal sides of the recess (3) on the raw component (1) is greater than the wall thickness (s) on the end faces of the recess (3), wherein the flattened areas () are produced in the respective area of ​​the greater wall thickness (S) on the outer diameter of the raw component (1), such that the raw component (1) is produced with thin walls. [7] Method according to one of claim 6, characterized by , that at least a flattening (5, 7) is produced starting from the axial end of the raw component (1) which serves to receive the cam roller (41) in the receptacle (3). [8] Forming tool (31, 34, 36) for manufacturing a roller tappet (44) for a pump or valve train of an internal combustion engine in a method according to one of claims 1 to 7, characterized by, that the tool cutting edge (32, 35, 37) has a profile shape with at least one convex rounding (33) for deburring with low notch effect by turning at least one edge (12 to 18) produced by at least one flattening (5, 6, 7, 8) on the outer diameter of the raw component (1) of the housing (42) of the roller tappet (44). [9] Forming tool (31, 34) according to claim 8, characterized by , that the tool cutting edge (32, 35) has a profile with several convexly curved radii (33) for the simultaneous, low-notch deburring of several edges (12 to 18) produced by turning on the outer diameter of the raw component (1) of the housing (42). [10] Roller tappet (44) for a pump or valve train of an internal combustion engine, which is manufactured in a lightweight construction using a method according to any one of claims 1 to 7.

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