Internal lever for a switchable rocker arm

Abstract

Inner lever (1) for a switchable rocker arm (2) of a valve train of an internal combustion engine, which can be arranged in a relatively pivotable manner in a longitudinal recess (4) of an outer lever (3) of the switchable rocker arm (2), which inner lever (1) consists of a box-like main part (5) with two opposing, upright and thin-walled side walls (6), between which a cam contact surface (16) can be provided, wherein the side walls (6) are connected at one end (7) by an upright and thin-walled crossbar (8), which has a drive surface (9) applied to its underside (18) for a coupling slide that can be brought forward longitudinally by the outer lever (3), which side walls (6), facing away from this end (7), transition into two strongly cranked, upright and thin-walled arms (10), characterized in that the inner lever (1) is manufactured from sheet steel by stamping and bending.wherein the arms (10) extend towards the other end (11) of the inner lever (1) in each upright and thin-walled longitudinal beam (12) with mutually aligned openings (13) for an axis (14) for pivotally movable connection with the outer lever (3), wherein the longitudinal beams lie against each other with their inner surfaces (15) and wherein the longitudinal beams (12) are spot-welded together or along a line, and wherein a projection (21) for centrally guiding the inner lever (1) in the longitudinal recess (4) of the outer lever (3) projects from the outer surfaces (20) of the side walls (6) of the box-like main part (5), which projections (21) are formed from the side walls (6) by stamping and extrusion.

Description

The invention relates to an inner lever for a switchable rocker arm of a valve drive of an internal combustion engine, which can be arranged in a relatively pivotable manner in a longitudinal recess of an outer lever of the switchable rocker arm, which inner lever comprises a box-like main part with two mutually opposite, upright and thin-walled side walls, between which a cam contact surface can be provided, wherein the side walls are connected at one end by an upright and thin-walled crossbar, which has a driver surface applied to its underside for a coupling slider which can be guided longitudinally by the outer lever, which side walls, facing away from this end, merge into two upright and thin-walled arms which are cranked strongly towards one another.Such an inner lever is known from FIGS. 2, 3 of U.S. Pat. No. 5,544,626. It has a box-like main part with two side walls. At one end, the side walls are connected by a cross beam, the entire underside of which is provided for contact with a coupling slide of an outer lever. At the other end of the inner lever, the side walls terminate in a common, one-piece longitudinal beam. The lever is a complex and expensive solid part to produce, which has a considerable disadvantageous effect in mass production.U.S. Pat. No. 6,199,527 B1 discloses a rocker arm of a standard valve drive made of sheet steel with two upright side walls and a crossbar with a spherical cap and a valve system. The side walls are bent from the cross beam.DE 198 17 849 A1 shows a roller rocker arm of a standard valve drive comprising two steel sheet plates bent together. At the bending center of the two plates, a valve contact screw is arranged.A further rocker arm made of steel sheet, here for a standard valve drive of a two-wheeler, is disclosed in DE 10 2005 046 897 A1. The rocker arm has a generally U-shaped cross section. Its side walls extend in the bore region for a cam follower roller in the same direction at right angles.A steel plate lever for a pump-nozzle drive of a fuel injection device, the side walls of which are connected by a central bushing, is disclosed in DE 102 37 448 A1.It is an object of the invention to provide an inner lever for a switchable rocker arm which is light-weight, stable and inexpensive.According to the invention, this object is achieved in that the inner lever is manufactured from sheet steel by punching and bending, wherein the arms are each continued in the direction of the other end of the inner lever in an upright and thin-walled longitudinal beam with mutually aligned openings for an axis for pivotally movable connection to the outer lever, wherein the longitudinal beams lie with their inner sides against one another and wherein the longitudinal beams are welded to one another in a punctiform or linear manner and wherein a protrusion for the central [aligned] guidance of the inner lever in the longitudinal recess of the outer lever projects from outer surfaces of the side walls of the box-like main part, wherein the protrusions are shaped from the side walls by embossing and extrusion.Thus, an inner lever for a switchable rocker arm is present, in which the disadvantages cited at the beginning are eliminated.By forming the inner lever from sheet steel, the latter can be produced economically overall. The inner lever can be produced, for example, from sheet metal strip on a punching and bending press which comprises a plurality of drawing and bending stages, the longitudinal beams of which are connected to one another at the other end by welding. Alternatively, outside the invention, gluing, soldering, snapping or the like is suitable. At the same time, a projection for guiding the inner lever in the longitudinal recess of the outer lever should project from outer surfaces of the side walls. The two projections are produced without machining by "stamping". The inner lever can run aligned on inner surfaces of the arms of the outer lever via outer sides of the projections. Thus, there is always an exact assignment of the coupling means to its driver surface in the cross beam.According to expedient developments of the invention, the openings for the axle and the roller bolt in the inner lever are to be punched out as well, so that complicated drilling, rubbing, etc. according to the prior art are dispensed with.The contour of the driver surface on the underside of the crossbar at one end is embossed according to a concrete embodiment of the invention. It is expediently designed to be complementary to an outer jacket of the coupling means that can be guided on by the outer lever. If the coupling means is formed, for example, in the manner of a piston, the driver surface can be formed in the manner of a half shell.Finally, it is provided that the longitudinal beams, viewed from one end to the other end behind their openings, run out in a finger-like projection which is reduced in height by flattening. The blanking may be performed during the punching and bending of the inner lever, or before, at one end of its "rough" contour cut. The shoulder serves for bearing a lost motion spring, such as a torsion leg spring, which runs in the region of the axis. Alternatively, it is also conceivable to punch out the height-reduced finger-like projection.The invention is expediently explained in more detail with reference to the drawings. The following are shown: FIG. 1 is a top view of a cam follower with an installed inner lever; and FIG. 2 shows a three-dimensional view of the inner lever according to the invention.The figures disclose a box-like inner lever 1 made of thin-walled steel sheet. The inner lever 1 is provided for installation in a switchable cam follower 2 of a valve drive of an internal combustion engine, which is designed as a "deactivation lever" according to FIG. 1. An outer lever 3 of the tow lever 2 has a longitudinal recess 4, in which the inner lever 1 can be arranged or is arranged. In the region of another end 11, the levers 1, 2 are traversed by an axle 14, so that they are relatively pivotable relative to one another.Referring to FIG. 2, the inner lever 1 comprises a box-like main part 5 with two thin-walled side walls 6 lying opposite one another. At one end 7, the side walls 6 are integrally connected to one another by a thin-walled transverse beam 8 which has on its underside 18 a driver surface 9, indicated here, for a coupling means (slide or the like) which can be guided longitudinally out of the outer lever 3 (from the direction from the one end 7) for the coupling situation.In the direction of the other end 11, the side walls 6 merge into thin-walled arms 10 which are greatly cranked toward one another and which are continued in thin-walled longitudinal beams 12 which lie against one another with their inner sides 15 or are welded, for example. The longitudinal beams 12 run out directly at the end side in height-reduced extensions 19 which, as can be seen from FIG. 1, serve for bearing a lost motion spring and are generated, for example, by flattening.Furthermore, it can be seen from FIG. 2 that the side walls 5 each have a circular cylindrical opening 17 which is stamped here and serves to receive a bolt for mounting a roller as a cam contact surface 16.As explained, the inner lever 1 (optionally also the outer lever 3) should consist of thin-walled steel sheet. In this case, it is produced in a punching and bending process, for example, from sheet metal strip having a thickness of approximately 2.5 mm. A bending line for the sheet metal blank after punching out its raw contour and the flattening of the projections 19 and the punching of the openings 13, 17 runs centrally in the region of the cross beam 8, virtually on a longitudinal central plane through the inner lever 1.It is advantageous if, in the assembled state, the outer lever 3 follows the inner lever 1 at least to the greatest possible extent with its contour.If necessary, it is conceivable and provided to form the region of the longitudinal beams 12 separately at the other end 11 and to connect them to the box-like main part 5 by suitable connecting measures such as welding.As can also be seen from FIG. 2, a projection 21 protrudes from each outer surface 20 of the corresponding side wall 6. This serves for an aligned guidance of the inner lever 2 on inner sides of the outer lever 3 in the event of installation.If the roller that can be seen from FIG. 1 is not provided as a cam contact surface 16, a separate contact plate can also be applied, which then connects upper sides of the side walls 6 and is likewise welded to them, for example.List of Reference Numbers1 Inner lever 2 Cam follower 3 Outer lever 4 Longitudinal recess 5 Main part 6 Side wall 7 of one end 8 Cross beam 9 Driver surface 10 Arm 11 Other end 12 Longitudinal beam 13 Opening 14 Axle 15 Inner side 16 Cam contact surface 17 Opening 18 Lower side 19 Projection 20 Outer surface 21 Projection

Claims

An inner lever (1) for a switchable rocker arm (2) of a valve drive of an internal combustion engine, which can be arranged in a relatively pivotable manner in a longitudinal recess (4) of an outer lever (3) of the switchable rocker arm (2), which inner lever (1) comprises a box-like main part (5) with two opposite, upright and thin-walled side walls (6), between which a cam contact surface (16) can be provided, wherein the side walls (6) are connected at one end (7) by an upright and thin-walled crossbar (8) which has a driver surface (9) applied to its underside (18) for a coupling slide which can be guided longitudinally by the outer lever (3), which side walls (6), facing away from this end (7), merge into two arms (10) which are strongly cranked towards one another, upright and thin-walled, the inner lever (1) being manufactured by punching and bending from steel sheet, wherein the arms (10) are each continued in the direction of the other end (11) of the inner lever (1) in an upright and thin-walled longitudinal beam (12) with mutually aligned openings (13) for an axle (14) for pivotably movable connection to the outer lever (3), wherein the longitudinal beams lie against one another with their inner sides (15), and wherein the longitudinal beams (12) are welded to one another in a point-shaped or line-shaped manner, and wherein projecting from outer surfaces (20) of the side walls (6) of the box-like main part (5) is in each case one projection (21) for centrally guiding the inner lever (1) in the longitudinal recess (4) of the outer lever (3), which projections (21) are formed by embossing and extrusion from the side walls (6).Inner lever according to Claim 1, characterized in that the openings (13) for the axle (14) are stamped at the other end (11).Inner lever according to Claim 1, characterized in that the side walls (6) are provided with mutually aligned openings (17) for arranging a bolt for a roller as a cam contact surface (16), which openings (17) are stamped.Inner lever according to Claim 1, characterized in that the driver surface (9) is stamped on the underside (18) of the crossbar (8) and is designed as a lens-like or rectangular-like indentation.Inner lever according to Claim 1, characterized in that the longitudinal beams (12), viewed in the direction from one end to the other (7, 11) behind their openings (13), run out in a finger-like shoulder (19) which is reduced in height by flattening.

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