Intermediate lever of a variable-stroke valve train of an internal combustion engine

Abstract

Proposed is an intermediate lever (1) of a variable-stroke valve train of an internal combustion engine, comprising two side walls (2) which protrude at one longitudinal end (3) from a lower part (4) connecting them and at the other longitudinal end (5) have two bores (6) with an axis (8) carrying a support roller (7). These side walls (2) have two receptacles (9) in their longitudinal center region, in which a bolt (12) is seated, which carries a roller (10) for starting a lifting cam from a front longitudinal end face (11) of the intermediate lever (1). The lower part (4) extends the intermediate lever (1) beyond its front and rear longitudinal end faces (11, 13) with a base piece (14, 15) each extending from the side walls (2) and has a guide track (16) on the outside for contact with a valve actuating lever.wherein at one longitudinal end (3) on the rear longitudinal end face (13) there is a contact surface (12) for a transversely acting spring finger (17) of a cam return spring (18) for the intermediate lever (1), which contact surface (12) is formed directly on longitudinal ends (19) of the side walls (2) located on the rear longitudinal end face (13), and wherein a positional fixation of the spring finger (17) of the cam return spring (18) in its axial direction is provided on outer or inner wall regions (20, 21) of the side walls (2).

Description

[0001] The invention relates to an intermediate lever of a variable-lift valve train of an internal combustion engine, with two side walls which protrude at one longitudinal end from a lower part connecting them and at the other longitudinal end have two bores, either with an axis carrying at least one support roller therein or for pivotally mounting on an axis fixed to the cylinder head, which side walls have two receptacles in their longitudinal center region in which a bolt is seated which carries a roller for starting a lifting cam from a front longitudinal end face of the intermediate lever,wherein the lower part extends the intermediate lever beyond its front and rear longitudinal end faces with a foot piece each extending from the side walls and has a guide track on the outside for contact with a valve actuating lever, and wherein at one longitudinal end on the rear longitudinal end face there is a contact surface for a transversely acting spring finger of a cam return spring for the intermediate lever, and wherein the foot piece of the lower part is closed at the rear longitudinal end face.

[0002] A generic intermediate lever, intended for a fully variable valve train, is described in DE 10 2016 223 088 A1. Its tab, positioned at one end on the base piece, serves to attach a transversely acting spring finger of a cam return spring. The guide track, applied to the outside of the base piece, is closed, with the spring finger extending the guide track.

[0003] The document DE 10 2016 220 401 A1 shows an intermediate lever with a transverse arrangement of a spring finger of a cam return spring.

[0004] Out of Fig. 3 of DE 10 2016 220 396 A1 discloses an intermediate lever, from whose guide track a tab is bent and raised. A transversely acting spring finger of a cam return spring is provided in specially prepared recesses in the rear longitudinal end faces of the side walls.

[0005] Another intermediate lever is described in DE 10 2020 123 364 A1. A tab is cut from the base of its lower part on the rear longitudinal end face and bent upwards. The tab serves as a contact surface for a transversely acting spring finger of a cam return spring, which is a torsion spring.

[0006] Document CN 2 06 889 038 U discloses an intermediate lever, which is provided at the other longitudinal end for pivoting support on an axle. The base of the lower part is open in a fork-like manner at the rear longitudinal end. A spring finger of a cam return spring engages longitudinally in the thus formed recess.

[0007] The task is to create a cost-optimized intermediate lever whose contact area for the spring finger of the cam return spring can withstand high loads, while at the same time providing good guidance of the spring finger.

[0008] According to the invention, this object is achieved in that the contact surface for the transversely acting spring finger of the cam return spring is formed, without additional component, directly on the longitudinal ends of the side walls located on the rear longitudinal end face, wherein a positional fixation of the transversely acting spring finger of the cam return spring in its axial direction is provided on outer or inner wall regions of the side walls, wherein the outer or inner wall regions of the side walls act as form-fitting contours in the longitudinal section at their contact surface and either a fixation of an end-face bent area or a countersunk area of ​​the spring finger is provided on inner wall regions of the side walls of the intermediate lever or outer wall regions of the side walls are provided for holding bent areas of a shaped bracket piece of the spring finger that overlaps the side walls.

[0009] This design is expressly intended for a transversely acting spring finger of the cam return spring, which cam return spring is particularly preferably a torsion spring. Alternatively, a transversely acting leaf spring or similar is also conceivable. The force of the spring finger is thus introduced by its direct transverse support on the longitudinal ends of the side walls immediately in front of / on an inner side of the base piece on the rear longitudinal end. A separate contact tab is not provided. By omitting the contact tab, the production of the intermediate lever is simplified and thus more cost-effective. On the other hand, a closed and therefore very robust base piece of the lower part on the rear longitudinal end is created. This also improves the counter-rotation of the roller of the valve actuating lever (rocker or rocker arm).The spring finger of the cam return spring is simply fixed in its axial direction on wall areas of the side walls. These wall areas do not require any special preparation for this purpose and act as positive-locking contours. A spring finger end offset or recess is either fixed on the inner wall areas of the side walls of the intermediate lever, or outer wall areas of the side walls can be provided for holding offset sections of the spring finger.

[0010] According to an expedient development of the invention, the contact surface on the longitudinal ends of the side walls is separately embossed and / or provided with a hard material coating. These measures serve to protect the contact area from wear.

[0011] Finally, it is proposed that the intermediate lever be made of sheet metal. If necessary, it can also be solid or manufactured using a primary forming process such as metal injection molding.

[0012] About the drawing: • The Fig. 1 - 3 show the intermediate lever with different designs of the spring finger of the cam return spring, which rests directly transversely on the side walls.

[0013] The intermediate lever 1 is positioned using the Fig. 1. It is made of sheet steel and has two side walls 2, which protrude at one longitudinal end 3 from a base-like lower part 4 connecting them in one piece, thus forming a U-shaped profile. The lower part 4 is extended beyond its front and rear longitudinal end faces 11, 13 by a base piece 14, 15 extending from the side walls 2. On an outer side 27 of the lower part 4, a continuous guide track 16 is formed for contact with a roller of a valve actuating lever, such as a rocker arm.

[0014] In their longitudinal center region 26, the side walls 2 have two receptacles 9. A bolt 29 is seated in these receptacles, which carries a roller 10 for the engagement of a lifting cam from a front longitudinal end face 11 of the intermediate lever 1 (here acting from below). At the other longitudinal end 5, the side walls 2 taper open like a fork and are stiffened at the front longitudinal end face 11 by a cross bar 25. In the section of this other longitudinal end 5, the side walls 2 have two further bores 6 with an axis 8 therein. The latter carries a support roller 7, or more precisely, a support roller assembly. In this area, contact between eccentric and guide means for the intermediate lever 1 is provided.

[0015] The intermediate lever 1 has a contact surface 12 for a transversely engaging spring finger 17 of a cam return spring 18 at one longitudinal end 3 on the rear longitudinal end face 13 (shown here at the top). This contact surface 12 is formed directly on the longitudinal ends 19 of the side walls 2, adjacent to the inner sides of the closed base piece 15. These longitudinal ends 19 can also be embossed / widened in the contact area for improved wear protection. An additional contact part such as an upwardly projecting tab or the like is not provided for the spring finger 17.

[0016] Examples of different axial guidance options for the spring finger 17 of the cam return spring 18 are shown in the figures. Fig. 1 inner wall areas 21 of the side walls 2 a non-specially prepared form-fitting contour for a recessed area 22 of the spring finger 17. After Fig. 3, the spring finger 17 is also axially mounted on the inner wall areas 21 of the side walls 2. The spring finger 17 has a bent end face area 24. According to Fig. 2, outer wall areas 20 of the side walls 2 act as a form-fitting contour for the spring finger 17. The latter engages over the side walls 2 with a shaped bracket piece 28. It can be seen that opposite bent areas 23 of the bracket piece 28 rest against the outer wall areas 20 of the side walls 2. List of reference numbers 1 intermediate lever 2 side wall 3 Longitudinal end 4 Lower part 5 Longitudinal end 6 Hole 7 Support roller 8 axis 9 Recording 10 rolls 11 Longitudinal front side 12 Contact surface 13 Longitudinal front side 14 Foot piece 15 Foot piece 16 Slide track 17 spring fingers 18 Cam return spring 19 Longitudinal forehead 20 exterior wall area 21 Interior wall area 22 Area 23 Area 24 area 25 cross bars 26 Longitudinal center area 27 Outside 28 bracket pieces 29 bolts

Claims

[1] Intermediate lever (1) of a variable-stroke valve train of an internal combustion engine, with two side walls (2) which protrude at one longitudinal end (3) from a lower part (4) connecting them and at the other longitudinal end (5) have two bores (6), either with an axis (8) carrying at least one support roller (7) therein or for pivotally movable mounting on an axis fixed to the cylinder head, which side walls (2) have in their longitudinal center region (26) two receptacles (9) in which a bolt (29) is seated which carries a roller (10) for starting a lifting cam from a front longitudinal end face (11) of the intermediate lever (1), wherein the lower part (4) extends the intermediate lever (1) beyond its front and rear longitudinal end faces (11, 13) with a foot piece (14, 15) each extending from the side walls (2) and on the outside a guide track (16) for contact with a valve operating lever,wherein at one longitudinal end (3) on the rear longitudinal end face (13) there is a contact surface (12) for a transversely acting spring finger (17) of a cam return spring (18) for the intermediate lever (1) and wherein the foot piece (15) of the lower part (4) is closed at the rear longitudinal end face (13), , characterized bythat the contact surface (12) for the transversely acting spring finger (17) of the cam return spring (18) is formed, without additional component, directly on longitudinal ends (19) of the side walls (2) located on the rear longitudinal end face (13), wherein a positional fixing of the transversely acting spring finger (17) of the cam return spring (18) in its axial direction is provided on outer or inner wall regions (20, 21) of the side walls (2), wherein the outer or inner wall regions (20,21) of the side walls (2) in the longitudinal section at their contact surface (12) act as positive-locking contours and either on inner wall areas (21) of the side walls (2) of the intermediate lever (1) a fixation of a bent-over area (24) or a countersunk area (22) of the spring finger (17) is provided or outer wall areas (20) of the side walls (2) are provided for holding bent areas (23) of a shaped bracket piece (28) of the spring finger (17) that overlaps the side walls (2). [2] Intermediate lever according to claim 1, characterized by that the contact surface (12) for the spring finger (17) of the cam return spring (18) on the longitudinal ends (19) of the side walls (2) is designed as an embossed surface and / or is provided with an applied hard material layer. [3] Intermediate lever according to claim 1, characterized by that the intermediate lever (1) is made of sheet metal.

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