DE102021120356A1 - Method for producing a base body for an intermediate lever and an intermediate lever, each for a variable-stroke valve train of an internal combustion engine - Google Patents

Abstract

Proposed is a method for producing a base body (1) of an intermediate lever (2) for a variable-stroke valve train of an internal combustion engine, which base body (1) is made in one piece from sheet metal with two spaced side walls (3) with an upper and a crossbar, the side walls (3) connecting lower part (4, 5), which lower part (5) widens the base body (1) with a base piece (11, 12) each and has a link track (13) on the outside for contact with a valve opener and on a base piece ( 11) a tab (19) acting as an abutment for a cam return spring is cut off in sections from the link track (13) and bent in the direction of the upper part (4). What is outstanding here is that after a blank (14) has been punched out of a circuit board, a central area (15) is formed into a U-profile piece (16) and the link track (13) is stamped and that the tab (19) is then cut and bent will.

Description

The invention relates to a method for producing a base body made of sheet metal for an intermediate lever for a variable-lift valve train of an internal combustion engine according to the features of the preamble of claim 1. The invention also relates to an intermediate lever with a base body made of sheet metal for a variable-lift valve train of an internal combustion engine according to the features of the subordinate claim 2.

In the EP 1 573 174 B1 described.

The shows another intermediate lever DE 10 2011 003 898 A1 . It goes out 2 the bent-up flap marked "21" emerges, which does not or hardly protrude beyond the base-like base body. The tab serves as a contact at the end of a leg of a torsion spring running along the intermediate lever as a cam return spring for the intermediate lever. The status here is that before deep-drawing and embossing a U-shaped, central profile piece in the board, the tab is cut and bent up to form the basic base-like contour.

Also goes out of the CN 206889038 U an intermediate lever emerges, here for pivotable mounting via its upper part on an axis.

The object of the invention is to create a base body made of sheet metal for an intermediate lever or an intermediate lever with a base body made of sheet metal with an optimized tab.

1. A) Stanzen eines Rohlings aus einer Platine, aufweisend ein mittiges Grundstück, von dessen Flanken lateral je ein flügelartiger Ansatz weg steht;
2. B) Tiefziehen des Grundstücks zu einem U-Profilstück zur Darstellung einer standfußartigen Grundkontur des Unterteils und Prägen der Kulissenbahn;
3. C) Einschneiden der Kontur der Lasche in die Kulissenbahn und Hochbiegen der Lasche von der Kulissenbahn weg, wobei einerseits Schnittlinien in der Kulissenbahn für die Lasche, in Kulissenrichtung zum anderen Fußstück hin gesehen, hinter einem Biegeradius der Lasche auslaufen und wobei andererseits die Lasche derartig lang ist, dass sie über das Unterteil hinaus in den für die Rolle vorgesehenen Längsmittenbereich ragt und
4. D) Aufbiegen der flügelartigen Ansätze zur Bildung der Seitenwände.

According to the invention, this object is achieved by the characterizing features of method claim 1:

1. A) Punching a blank from a circuit board, having a central property, from the flanks of which a wing-like attachment protrudes laterally;
2. B) Deep-drawing of the property to form a U-profile piece to represent a base-like base contour of the lower part and embossing of the link track;
3. C) Cutting the contour of the tab into the link track and bending the tab up away from the link track, with on the one hand cutting lines in the link track for the tab, seen in the direction of the link towards the other foot piece, running out behind a bending radius of the tab and on the other hand the tab being so long is that it protrudes beyond the lower part into the longitudinal center area provided for the roll and
4. D) Bending up the wing-like projections to form the side walls.

This optimized process makes it possible to produce a base body for an intermediate lever in which there is comparatively little stress in the "connection area" of the link plate to the link track. There is no pre-damage to the sheet metal in this area due to torsion, warping, etc. When deep-drawing, the property fills out its counter-mold in the die as well as it should, which results in sharp-edged transitions from the link track to its side walls. The cut edges, which only come to an end "behind" the beginning of the bending radius for the tab, give the tab, which is visibly longer than in the prior art, additional elasticity because, simply put, there is a longer lever arm when the spring acts. The embossing process of the slotted link track can take place at the same time as or after the drawing process. If necessary, the link path can also be represented by another method, such as grinding or the like, for example only carried out after step D).

The highlight is therefore a reversal of the process steps used to date, in which the tab was first cut out of the plate and bent and then the property was pulled into a U-shaped profile piece, which led to high stresses in the edge area just described with material distortions etc.

Optionally, process step D) can also be carried out before step C). This has no influence on the quality of the above edge area.

Such an intermediate lever can be used universally because of the extended lug, which in a further development of the invention (both variants) intersects the contour of the central roller in the shoring. Although it is particularly suitable for a now transverse support of a leg of a torsion spring (keyword: "emigration"). Under certain circumstances, however, depending on the valve train layout, the leg can also lie on the tab in the direction in which it extends.

Alternatively, this object is achieved by the features of the characterizing part of independent claim 2. According to this, a transitional area of the link track to the bracket, which has an end area of the zero lift section, is provided with cutting lines which, seen in the link direction from one base piece to the other, end behind a bending radius of the bracket.

Thus, this transition area, which has an end piece of the zero lift area, seen from the one base piece, has a certain elasticity or spring property in the longitudinal direction of the lever. Sudden increases in force when the intermediate lever overruns with the zero lift section of the link track on the end-profiled roller of the valve opener, for example in the shut-off mode of the gas exchange valve in question, are thereby dramatically reduced or eliminated. Such increases in force can otherwise, due to a slight protrusion of the convex roller with its center between a free space created by the strap on one foot piece, when the roller overruns over the beginning of the "fixed" area of the link track (in the direction of the other area carrying the lifting curve ), lead to undesired loading of the valve spring of the respective (closed) gas exchange valve and/or to a slight "retraction" of the "stiff" hydraulic support element.

Further dependent claims relate to a width-graded design of the base body or intermediate lever with base body. Accordingly, this has its smallest width in the area of the supporting foot-like lower part. In contrast, the longitudinal central area of the roller, in which case a sliding surface is also conceivable and provided, can be “bulged out”. In addition, the section of the upper part can in turn be expanded compared to the longitudinal center area. The connection is made via cranked side wall sections.

Finally, it is proposed to stiffen the side walls in the area of the upper part by means of crossbars that are joined together. With regard to the installation space, it is expedient to provide this stiffening on a longitudinal side of the base body facing away from the lug.

A lever-type cam follower such as a rocker arm or rocker arm is particularly suitable as the valve opener to be acted upon by the intermediate lever, whose contact partner to the intermediate lever is, as usual, a roller. However, counter-rotation on a roller of a tappet is also conceivable and provided for.

• • 1 zeigt eine räumliche Seitenansicht auf einen fertig montierten Zwischenhebel mit Grundkörper;
• • 2 zeigt den Hebel wie vorgenannt kopfüber;
• • 3 zeigt den gestanzten Rohling;
• • 4 zeigt den Rohling mit tiefgezogenem Grundstück und angeschnittener Kulissenbahn und
• • 5 zeigt den Rohling mit abgebogener Lasche und aufgestellten Seitenwänden.

About the drawing:

• • 1 shows a three-dimensional side view of a fully assembled intermediate lever with base;
• • 2 shows the lever upside down as above;
• • 3 shows the stamped blank;
• • 4 shows the blank with a deep-drawn base and cut link track and
• • 5 shows the blank with a bent flap and erected side walls.

• Der Grundkörper 1 besteht aus Stahlblech. Er hat zwei beabstandete Seitenwände 3. Diese liegen bei seinem Oberteil 4 gabelartig offen vor. Im Abschnitt seines Unterteils 5 ist der Grundkörper 1 querbügelartig geschlossen ausgeführt.

Based on 1 , 2 the structure of the completed intermediate lever 2 with base body 1 is described:

• The base body 1 consists of sheet steel. It has two spaced side walls 3. These are open in the form of a fork at its upper part 4. In the section of its lower part 5, the base body 1 is closed in the manner of a crossbar.

The base body 1 has two bores 6 in the upper part 4, in which an axle 8 is seated, which carries a support roller 7, more precisely a support roller set. A longitudinal central area 9 of the base body 1 accommodates a roller 10 for counter-running a lifting cam. The roller 10 runs on a bolt 21 which is accommodated in bores 22 of the longitudinal central area 9 .

How from the 1 , 2 removable, the lower part 5 of the base body 1 is widened on both sides with a foot piece 11, 12 in the lever pivoting direction. The section of the lower part 5 thus has a shape similar to a base. -Possibly. at least one of the foot pieces 11, 12 can also be present only in rudimentary form.

The lower part 5 has on its free outer side a sliding track 13, also called a working curve, for contact with a roller of a rocker arm with an end profile. from the in 1 Drawn on the left foot piece 11 is a tab 19 from the slide track 13 high. This protrudes into a height section of the longitudinal central area 9 and cuts how 1 shows the contour of the roller 10. A free outside of the tab 19 acts as a transverse contact of a leg of a torsion spring as a cam return spring for the intermediate lever 2. The arrow indication in 1 to reference number "10" shows the direction of attack of the lifting cam.

The side walls 3 are reinforced in the upper part 4, on the long side of the central cam attack, by transverse brackets 18 which extend from these in one piece and are welded to one another.

• Zunächst wird ein Rohling 14 aus einem Blechstreifen gestanzt. Dieser Rohling 14 (s. 3) hat ein mittiges Grundstück 15, von dessen Flanken lateral je ein flügelartiger Ansatz 20 (die späteren Seitenwände 3) weg steht. Danach wird das Grundstück 15 im Gesenk zu einem U-Profilstück 16 tiefgezogen, sodass es zur Ausbildung der standfußartigen Grundkontur des Unterteils 5 kommt. Zugleich oder in einem folgenden Arbeitsschritt wird die Kontur der Kulissenbahn 13 geprägt.

Based on 3 until 5 the manufacturing process of the base body 1 is explained:

• First, a blank 14 is stamped from a metal strip. This blank 14 (p. 3 ) has a central plot 15, from the flanks of which a wing-like extension 20 (the later side walls 3) protrudes laterally. Thereafter, the site 15 is deep-drawn in the die to form a U-profile piece 16, so that it forms the pedestal-like Grundkon door of the lower part 5 comes. At the same time or in a subsequent work step, the contour of the link path 13 is embossed.

how 4 shows, the tab 19, which is still to be bent over, protrudes like a finger from the profile piece 16, more precisely from its link track 13. Two incisions 17 in the link track 13 prepare a subsequent final bending process of the tab 13 from the finished profile piece 16 “down” (see arrow).

5 discloses the state of the base body 1 with the tab 19 already bent over. 2 shows in this context that the cutting lines 17 in the link track 13 run out “behind” the start of a bending radius R _B of the tab 19 . The arrow indication in 5 stands for the subsequent step of bending up the wing-like projections 20 to form the side walls 3.

The aforementioned incisions 17, which are clearly visible in the drawing, impart a certain resilient resilience to the link track 13 in the transition area on the lug 19, which has one end area of the zero lift section (see also the information on the advantages of the independent claim 2). Force peaks (loading of the gas exchange valve) when the intermediate lever 2 overruns on the end-profiled roller of the rocker arm are greatly reduced or eliminated.

Reference List

1)

body

2)

intermediate lever

3)

Side wall

4)

top

5)

lower part

6)

drilling

7)

support roller

8th)

axis

9)

Longitudinal center area

10)

role

11)

base

12)

base

13)

slide track

14)

blank

15)

property

16)

profile piece

17)

cutting line

18)

crossbar

19)

tab

20)

approach

21)

bolt

22)

drilling

RB)

Bending radius tab

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1573174 B1 [0002]
• DE 102011003898 A1 [0003]
• CN 206889038 U [0004]

Claims (6)

Base body (1) of an intermediate lever (2) for a variable-stroke valve train of an internal combustion engine, which base body (1) is made in one piece from sheet metal with two spaced side walls (3) with an open upper part and a lower part (4, 5) connecting the side walls (3) like a crossbar ) is shaped, which side walls (3) have two bores (6) in the upper part (4), either for an axle (8) carrying at least one support roller (7) or for pivoting mounting on an axle fixed to the cylinder head, with a longitudinal central region ( 9) of the base body (1) for arranging a roller (10) for at least indirect counter-rotation of a cam, with the lower part (5) widening the base body (1) on both sides with a base piece (11, 12), viewed in the lever pivoting direction and on the outside has a sliding track (13) for contact with a valve opener and wherein on one of the foot pieces (11) there is a lug (19) acting as an abutment for a cam return spring of the link track (13) is cut off in sections and bent in the direction of the upper part (4), characterized by the following steps for production: A) Punching a blank (14) from a circuit board, having a central property (15), from whose flanks each a wing-like extension (20) stands away; B) deep-drawing of the piece of land (15) to form a U-shaped profile piece (16) to produce a basic contour of the lower part (5) in the manner of a pedestal and embossing of the link track (13); C) Cutting the contour of the tab (19) into the link track (13) and bending the tab (19) up away from the link track (13), on the one hand cutting lines (17) in the link track (13) for the tab (19), viewed in the link direction towards the other foot piece (12), run out behind a bending radius (R _B ) of the bracket (19) and on the other hand the bracket (19) is so long that it extends beyond the lower part (5) into the for the role (10) provided longitudinal center area (9) and D) bending open the wing-like extensions (20) to form the side walls (3). Intermediate lever (2) for a variable-stroke valve drive of an internal combustion engine, the base body (1) of which is formed in one piece from sheet metal with two spaced side walls (3) with an open upper part and a lower part (4, 5) connecting the side walls (3) like a crossbar, which Side walls (3) in the upper part (4) have two bores (6), either with an axle (8) carrying at least one support roller (7) or for pivotable mounting on an axle fixed to the cylinder head, with a longitudinal central area (9) of the base body ( 1) has a roller (10) for at least indirect counter-rotation of a cam, with the lower part (5) widening the base body (1) on both sides with a foot piece (11, 12) as seen in the direction of lever pivoting and on the outside a link track (13) for one has contact with an end-profiled roller of a valve opener, and from the one foot piece (11) whose section of the link track (13) has a zero lift section, one as a support for an N tab (19), which acts as a cam return spring, is cut off in sections from the link track (13) and bent in the direction of the upper part (4), characterized in that a transition area of the link track (13) to the tab (19), which has an end area of the zero lift section, with Cutting lines (17) are provided which, viewed in the link direction from one base piece (11, 12) to the other, end behind a bending radius (R _B ) of the tab (19). Basic body of an intermediate lever claim 1 or intermediate lever claim 2 , characterized in that the side walls (3) in the longitudinal central area (9) compared to the lower part (5) have a larger clear width. Basic body of an intermediate lever claim 1 or intermediate lever claim 2 , characterized in that the side walls (3) in the section of the upper part (4) have a greater clear width than in their longitudinal central area (9). Basic body of an intermediate lever claim 1 or intermediate lever claim 2 , characterized in that the tab (19) extends so far into the longitudinal central region (9) that it partially overlaps a contour of the roller (10). Basic body of an intermediate lever claim 1 or intermediate lever claim 2 , characterized in that the side walls (3) of the upper part (4) are reinforced by transverse brackets (18) which extend from them in one piece and are welded to one another.

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