Intermediate lever made of sheet metal for a variable-stroke valve train of an internal combustion engine

Abstract

Intermediate lever (1) made of sheet metal for a variable-stroke valve train of an internal combustion engine, with two side walls (2) which emerge from a base-like lower part (3) connecting them in a cross-brace-like manner and terminate in an open upper part (4), which side walls (2) in the upper part (4) have either at least one support roller (5) for a cam disc counter-rotation or a pivoting surface for mounting on an axis fixed to the cylinder head, wherein the side walls (2) carry a roller (7) serving at least for an indirect counter-rotation of a cam in their longitudinal center region (6), wherein the lower part (3) widens the intermediate lever (1) on both sides, viewed in its pivoting direction, with a base piece (8, 9) each and has a guide track (10) on the outside for contact with a valve opener, and wherein one base piece (8) has two fork-like open arms (11),from whose base (12) a tab (13) serving as a cam return spring mounting projects upward in the direction of the upper part (4) beyond the outer ends (14) of the side walls (2), which tab (13) is so long that it projects up to the longitudinal mid-region (6) of the side walls (2), at least partially overlapping the contour of the roller (7), characterized in that transition regions (15) of the arms (11) of one foot piece (8) to the side walls (2) are present as stepped sections, between which longitudinal sides (16) of the tab (13) are fixed by a clamping (17) such that the longitudinal sides (16) are only engaged with a partial region of their thickness.,

Description

[0001] The invention relates to an intermediate lever made of sheet metal for a variable-stroke valve train of an internal combustion engine, with two side walls which emerge from a base-like lower part connecting them in a cross-brace-like manner and which terminate in an open upper part, which side walls in the upper part have either at least one support roller for a cam disc counter-rotation or a pivoting surface for mounting on an axis fixed to the cylinder head, wherein the side walls carry a roller in their longitudinal center region which serves at least for an indirect counter-rotation of a cam, wherein the lower part widens the intermediate lever on both sides with a base piece each, viewed in its pivoting direction, and has a guide track on the outside for contact with a valve opener, wherein one base piece has two fork-like open arms,from the base of which a tab serving as a support for a cam return spring projects upwards in the direction of the upper part in front of the outer ends of the side walls and which tab is so long that it projects up into the longitudinal center region of the side walls, overlapping a contour of the roller at least in sections.

[0002] The general design of a sheet metal intermediate lever, intended for a fully variable valve train for throttle-free load control, is described in EP 1 573 174 B1.

[0003] DE 10 2017 110 171 A1 shows in Fig. 2 an intermediate lever, between whose fork-like open arms, near their end faces, an upright pin is clamped on one foot piece as a support for a leg of a cam return spring.

[0004] The document DE 10 2016 223 088 A1 discloses an intermediate lever with closed base pieces, wherein a tab is bent from the end face of one of the base pieces in the longitudinal direction of the lever, which tab serves for the external attachment of a leg of a torsion spring.

[0005] The document CN 206 889 038 U discloses an intermediate lever with a base piece arranged only on one side, from which a tab protrudes approximately in a longitudinal center region as a torsion spring system.

[0006] In CN 1 09 519 245 A, an intermediate lever with a fork-like open base piece with a T-shaped tab for the transverse attachment of an end leg of a torsion spring is shown (see e.g. Fig. 2), which extends to the roller in the longitudinal center area. The tab rests with its cross member on the outer ends of the side walls.

[0007] Another intermediate lever is shown in DE 10 2011 003 898 A1. Fig. 2, the short, bent-up tab, labeled "21," protrudes slightly or not at all beyond the base-like body. The tab serves as a terminal support for a leg of a torsion spring running lengthwise to the intermediate lever, serving as a cam return spring for the intermediate lever.

[0008] It is an object of the invention to provide an intermediate lever whose tab is suitable for a comparatively large excursion of the leg of the cam return spring or for a comparatively "high" engagement of the cam return spring thereon and which intermediate lever is at the same time particularly stiff.

[0009] According to the invention, this object is achieved in that transition regions of the arms of one foot piece to the side walls are present as step sections, between which longitudinal sides of the tab are fixed by means of a clamp in such a way that the longitudinal sides are only gripped with a partial area of ​​their thickness.

[0010] The intermediate lever is ideally suited for a transverse support of an end leg of the cam return spring, which is a torsion spring, although longitudinal systems or other types of springs can of course also be used for the return.

[0011] Thanks to the inventively cleverly designed stepped lateral transition areas, the lower section of the link plate is supported laterally and stiffened. On the other hand, the link plate is additionally held / clamped in this lower section, so that its lever arm is shortened when the spring engages. This also has advantages during a hardening process towards the end of the intermediate lever manufacturing process, as less warping, etc. can be expected. According to the invention, the link plate protrudes slightly from its “frame” at the transition areas. This makes spring contact possible over almost its entire length without side wall contact occurring when the spring end leg is curved. The innovative intermediate lever has a support roller / support roller package in its upper section for counter-rotation on a curved track. Alternatively, it can be used, for example.also have two holes in this section, via which it can be pivotally mounted on an axis of the cylinder head.

[0012] To secure the tab, a further development of the invention proposes a squeezing process applied laterally to the transition areas, e.g., in a die. In other words, this can also be referred to as embossing, clinching, or caulking.

[0013] Further subclaims relate to practical designs of the side wall area of ​​the intermediate lever. Accordingly, it is proposed to provide the intermediate lever with a smallest clear width in its base area, a wider width in its longitudinal center area, and a largest clear width in the upper part.

[0014] Due to the box-like geometry of the other foot piece (U-shaped cross-section) proposed in the specification, there is a further contribution for a particularly stiff intermediate lever.

[0015] As further suggested, the two arms flanking the tab of one of the foot pieces should have a rod-like design. This saves material and creates space.

[0016] A lever-like cam follower such as a rocker arm or rocker arm is particularly suitable as the valve opener to be actuated by the intermediate lever. However, a counter-rotating mechanism on a tappet roller is also conceivable and intended.

[0017] About the drawing: • Fig. 1 shows a spatial side view of the intermediate lever and • Fig. 2 shows a side view of the intermediate lever after Fig. 1 “from behind”.

[0018] The figures show an intermediate lever 1 for a variable-stroke valve train of an internal combustion engine. The intermediate lever 1 consists of a base made of sheet steel. It has two side walls 2. These emerge from a single-piece base-like lower part 3, on the free outer side of which a guide track 10 is formed for contact with a rocker arm.

[0019] The side walls 2 terminate in an open upper part 4 and, in this section, carry a support roller assembly 5 for counter-rotation on a curved track. At the same time, the side walls 2 are stiffened at the upper part 4 by a cross bar 20. In their longitudinal center region 6, the side walls 2 carry a roller 7, which serves for counter-rotation of a cam, which counter-rotation according to Fig. 1 “from the left” is provided.

[0020] The side walls 2 are stepped in width, starting from the lower part 3. The lower part 3 has the smallest clear width. The longitudinal center section 6, in contrast, is widened. The upper part 4 has the largest clear width.

[0021] The above-mentioned lower part 3 widens the intermediate lever 1 in its pivoting direction on both sides with a foot piece 8, 9. The Fig. 1 shown on the left is a base piece 8 with two fork-like open arms 11. From a base 12 of these arms 11, a tab 13 projects upwards towards the upper part 4 in front of the outer ends 14 of the side walls 2. The comparatively long tab 13 serves to attach a transverse leg of a torsion spring as a cam return spring for the intermediate lever 1. The tab 13, as best seen from Fig. 1 can be removed, up to the longitudinal center area 6 of the side walls 2 with the roller 7.

[0022] The tab 13 is, as both figures show, additionally clamped in its lower section. For this purpose, transition areas 15 of the arms 11 of one foot piece 8 to the side walls 2 are deliberately designed as stepped sections, so that this edge area is not "grooved". The clamping / fixing is achieved by applying force to the transition areas 15 on the outside via a stamping tool, so that the long sides 16 of the tab 13 are "clamped". This is clearly visible from Fig. 2, that the longitudinal sides 16 of the tab 13 are not covered in their entire thickness.

[0023] For additional stiffening of the structure, the intermediate lever 1 has a box-like geometry (U-shaped cross-section) on the side of the other foot piece 9. The side surfaces 18 of the other foot piece 9 rise in a wedge-like manner, starting from its outer end 19. As can be seen from Fig.1, the two arms 11 of the opposite foot piece 8 have a largely rod-like, flat course. List of reference numbers 1 intermediate lever 2 side wall 3 Lower part 4 Top 5 support roller 6 Longitudinal center area 7 roll 8 of a foot piece 9 other foot piece 10 slide track 11 Arm 12 Reason 13 tab 14 Outer forehead 15 Transition area 16 long sides 17 Clamping 18 side surface 19 Outer forehead 20 cross bars

Claims

[1] Intermediate lever (1) made of sheet metal for a variable-stroke valve train of an internal combustion engine, with two side walls (2) which emerge from a base-like lower part (3) connecting them in the manner of a crossbar and which terminate in an open upper part (4), which side walls (2) in the upper part (4) have either at least one support roller (5) for a cam disc counter-rotation or a pivoting surface for mounting on an axis fixed to the cylinder head, wherein the side walls (2) carry a roller (7) serving at least for an indirect counter-rotation of a cam in their longitudinal center region (6), wherein the lower part (3) widens the intermediate lever (1) on both sides, viewed in its pivoting direction, with a base piece (8, 9) and has on the outside a guide track (10) for contact with a valve opener, and wherein one base piece (8) has two fork-like open arms (11),from the base (12) of which a tab (13) serving as a support for a cam return spring projects upwards in the direction of the upper part (4) in front of the outer ends (14) of the side walls (2), which tab (13) is so long that it projects upwards into the longitudinal center region (6) of the side walls (2), overlapping a contour of the roller (7) at least in sections, , characterized by that transition areas (15) of the arms (11) of one foot piece (8) to the side walls (2) are present as step sections, between which longitudinal sides (16) of the tab (13) are fixed by means of a clamp (17) in such a way that the longitudinal sides (16) are only gripped with a partial area of ​​their thickness. [2] Intermediate lever according to claim 1, characterized by that the clamping (17) of the transition areas (15) on the long sides (16) of the tab (13) is represented by embossing, clinching or caulking applied on the outside. [3] Intermediate lever according to claim 1, characterized bythat the side walls (2) of the lower part (3) have an inherently drawn-in profile compared to the longitudinal center region (6). [4] Intermediate lever according to claim 1 or 3, characterized by that the side walls (2) have a retracted course in their longitudinal center region (6) compared to the upper part (4). [5] Intermediate lever according to claim 1, characterized by that the intermediate lever (1) has a box-like geometry on the side of the other foot piece (9), with side surfaces (18) of this foot piece (9) merging into the side walls (2) in a wedge-like manner, starting from its outer end (19). [6] Intermediate lever according to claim 1, characterized by that the two arms (11) of one foot piece (8) have a rod-like, flat course. [7] Intermediate lever according to one of the preceding claims, characterized by that the tab (13) is provided for a transverse contact of an end leg of a cam return spring designed as a torsion spring.

Images