Method for manufacturing main body of intermediate arm of variable stroke valve mechanism of internal combustion engine

Abstract

The invention relates to a method for producing a body of an intermediate arm of a variable-lift valve train of an internal combustion engine, which body (1) is formed in one piece from sheet metal and has two spaced-apart side walls (3) with upper portions (4) and lower portions (5) which connect the side walls (3) in a transverse yoke-like manner, which lower portions (5) extend the body (1) with a leg (11, 12) each and have a runner rail (13) on the outside for contact with a valve opener, and in which, on one leg (11), a tongue (19) is sectionally detached from the runner rail (13) and bent upward toward the upper portion (4) as an abutment for a cam return spring. The invention is distinguished in that, after the blank (14) has been punched from a sheet blank, a central base section (15) is formed inwardly as a U-profile section (16) and an embossed runner rail (13) is produced, and subsequently the tongue (19) is cut out and bent.

Description

Technical Field

[0001] The invention relates to a method for manufacturing the main body of an intermediate arm of a variable-stroke valve mechanism of an internal combustion engine, the main body being formed in one piece from sheet metal and having two spaced-apart side walls, the side walls having an open upper portion and a lower portion connecting the side walls in a transverse yoke-like manner, the side walls having two holes in the upper portion, which are either used for a shaft carrying at least one supporting roller or for a swingable support on a shaft fixed relative to a cylinder head, wherein the longitudinal center area of ​​the main body is configured to arrange rollers for at least indirect relative movement with respect to a cam, wherein, viewed in the swinging direction of the arm, the lower portion extends the main body to form legs on both sides and has a sliding groove rail on the outer side for contacting a valve opener, and wherein, on one of the legs, a tongue is sectionally separated from the sliding groove rail and bent upward as a contact portion for a cam return spring. Background Art

[0002] EP 1 573 174 B1 describes an intermediate arm which is provided for an unthrottled, load-controlled, fully variable valve train and a method for producing its main body from a sheet metal blank.

[0003] DE 10 2011 003 898 A1 shows another intermediate arm. Figure 2 A bent-up tongue, designated "21," protrudes little or not beyond the foot-shaped body. This tongue is used for contact with the end of a leg of a torsion spring, which serves as a cam return spring for the intermediate arm and extends along the intermediate arm. In this prior art, the upright tongue is cut out and bent to form the essentially foot-shaped basic contour before deep drawing and stamping the U-shaped central profile section from the sheet metal.

[0004] CN 206889038 U also discloses an intermediate arm which is used for pivotably mounting the intermediate arm on the shaft via its upper part. Summary of the Invention

[0005] The object of the present invention is to provide a method for the uncomplicated production of a body of a central arm with an optimized tongue.

[0006] According to the invention, this object is achieved as follows:

[0007] A) punching out a blank from a sheet metal blank, the blank comprising a central base section, with wing-shaped projections each protruding laterally from the flanks of the base section;

[0008] B) deep drawing the base section into a U-shaped profile section to present a lower foot-shaped base contour and emboss the slide rail;

[0009] C) cutting out the contour of the tongue in the guide rail and bending the tongue away from the guide rail, wherein, on the one hand, the cutting line for the tongue in the guide rail ends after the bending radius of the tongue, as seen in the direction of the guide rail toward the other leg, and wherein, on the other hand, the length of the tongue is such that it projects beyond the bottom into the longitudinal center region provided for the roller, and

[0010] D) Bend the wing-shaped protrusions to form the side walls.

[0011] This optimized method enables the production of a main body for the central arm, with relatively low stresses in the "connection area" between the tongue and the gate rail. Premature damage to the sheet metal in this area due to twisting, warping, etc. is not to be expected. During deep drawing of the base section, it ideally assumes its corresponding shape in the mold, resulting in a sharp-edged transition from the gate rail to its side walls. The cutting edge, which ends "after" the start of the tongue's bending radius, imparts additional elasticity to the tongue, which is significantly longer than in the prior art. Simply put, a longer lever arm is present when the spring is applied. The gate rail can be embossed simultaneously or after the drawing process. If necessary, the gate rail can also be formed using other methods, such as grinding, performed after step D).

[0012] The highlight is therefore that the method steps used previously are reversed, in which the tongue is first cut out of the sheet metal and bent, and the base section is subsequently drawn into a U-profile section, which would lead to high stresses in the edge region just described due to material warping, etc.

[0013] If necessary, method step D) can also be carried out before step C). This has no influence on the quality of the above-mentioned edge region.

[0014] Due to the extended tongue, which intersects the contour of the central roller in a further embodiment of the invention, this intermediate arm can be used universally. It is particularly suitable for laterally bracing the legs of the torsion spring (keyword: "deflection"). However, in some cases, depending on the layout of the valve train, the legs can also rest on the tongue in its extension direction.

[0015] The present invention also relates to a stepped width design of the body. Thus, the body has its smallest width in the foot-shaped lower region. The longitudinal center region can be correspondingly "bulged" at the rollers (where sliding surfaces are conceivable and provided, if necessary). Furthermore, the upper section can be widened again relative to the longitudinal center region. The connections are each realized via curved side wall sections.

[0016] Finally, it is proposed that the side walls are reinforced in the upper region by means of transverse yokes that engage with one another. In terms of installation space, it is expedient here if the reinforcement is arranged on the longitudinal side of the main body facing away from the tongue.

[0017] The cam follower of the arm shape such as rocker arm or swing arm is particularly suitable as the valve opener loaded by the intermediate arm.Yet, also can think of and be provided with the relative movement on the roller of tappet. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] in:

[0019] Figure 1 A spatial side view showing the middle arm with the main body after completion of assembly;

[0020] Figure 2 The arm as described above is shown inverted;

[0021] Figure 3 The stamped blank is shown;

[0022] Figure 4 shows a blank with a deep-drawn base section and a cut-out gate rail; and

[0023] and

[0024] Figure 5 A blank is shown with a bent tongue and upright side walls. DETAILED DESCRIPTION

[0025] Reference Figure 1 、 Figure 2 The complete structure with the main body 1 and the intermediate arm 2 is depicted.

[0026] The main body 1 is made of sheet steel and has two spaced-apart side walls 3. These side walls are open in a fork-like manner in their upper part 4. The main body 1 is designed to be closed transversely in the section of its lower part 5 in the manner of a yoke.

[0027] In the upper part 4, the body 1 has two holes 6 in which shafts 8 are mounted, carrying support rollers 7, or more precisely, support roller assemblies. The longitudinal center region 9 of the body 1 houses rollers 10 that rotate relative to the travel cam. The rollers 10 run on pins 21 that are received in holes 22 in the longitudinal center region 9.

[0028] As from Figure 1 、 2 It can be seen that the lower part 5 of the main body 1 is expanded on both sides in the direction of arm swing to form support feet 11 and 12. The section of the lower part 5 thus has a shape similar to a support foot. (If necessary, at least one of the support feet 11 and 12 can also only be preliminarily present.)

[0029] The lower part 5 has on its free outer side a guide rail 13, also called a working curve, which serves to contact the rollers of the rocker arm. Figure 1 From the foot 11 shown on the left side of the drawing, a tongue 19 protrudes from the guide rail 13. The tongue extends until it enters a certain height section of the longitudinal center region 9 and is as shown in FIG. Figure 1 As shown, it intersects the contour of the roller 10. The free outer side of the tongue 19 acts as a transverse abutment for the leg of a torsion spring, which serves as a cam return spring for the intermediate arm 2. Figure 1 The arrows indicated by reference numeral 10 in FIG. 1 show the direction of application of the stroke cam.

[0030] The side walls 3 are reinforced in the upper part 4 on the longitudinal sides of the central cam application part by transverse yokes 18 which are welded to one another and originate in one piece from the side walls.

[0031] Reference Figures 3 to 5 The manufacturing method of the main body 1 is described:

[0032] First, a blank 14 is punched out of a sheet metal strip. Figure 3 ) has a central base section 15, from whose flanks a wing-shaped projection 20 (later side walls 3) protrudes laterally. The base section 15 is then deep-drawn in a die to form a U-shaped profile section 16, thereby forming the foot-shaped basic contour of the lower part 5. Simultaneously or in a subsequent working step, the contour of the gate rail 13 is embossed.

[0033] like Figure 4 As shown, the tongue 19 that still needs to be bent protrudes like a finger from the profile section 16, more precisely from its sliding guide rail 13. Two cutouts 17 in the sliding guide rail 13 are prepared for the final bending process of the tongue 19 from the finished profile section 16 "downward" (see arrows).

[0034] Figure 5 The state of the body 1 with the tongue 19 having completed bending is disclosed. In this case, Figure 2 The bending radius R of the cutting line 17 in the sliding channel rail 13 at the tongue 19 is shown. B The starting point "after" ends. Figure 5 The arrow in FIG. 1 indicates the subsequent step of lifting the wing-shaped protrusion 20 to form the side wall 3 .

[0035] Reference Signs List

[0036] 1 Main body

[0037] 2 Intermediate arm

[0038] 3 Sidewalls

[0039] 4 upper part

[0040] 5 lower part

[0041] 6 holes

[0042] 7 Support rollers

[0043] 8-axis

[0044] 9 Vertical center area

[0045] 10 Scroll Wheel

[0046] 11 legs

[0047] 12 legs

[0048] 13 slide rail

[0049] 14 blanks

[0050] 15 Basic section

[0051] 16 profile sections

[0052] 17 Cutting Line

[0053] 18 Transverse yoke

[0054] 19 tongue

[0055] 20 bulge

[0056] 21 pins

[0057] 22 holes

[0058] R B Tongue bending radius

Claims

1. A method for manufacturing a main body (1) of an intermediate arm (2) of a variable stroke valve mechanism of an internal combustion engine, wherein the main body (1) is formed in one piece from a sheet material, characterized in that There are the following steps for manufacturing: A) punching out a blank (14) from a sheet metal blank, the blank comprising a central base section (15) with wing-shaped projections (20) protruding laterally from the flanks of the base section; B) deep drawing the base section (15) into a U-shaped profile section (16) to present a foot-shaped base contour of the lower part (5) and embossing the slide rail (13); C) cutting out the outline of the tongue (19) in the chute rail (13) and bending the tongue (19) away from the chute rail (13) and raising it upright, wherein on one hand, the lower part (5) causes the main body (1) to extend the legs (11, 12) on both sides, and when viewed in the direction of the chute toward the other leg (12), the cutting line (17) for the tongue (19) in the chute rail (13) is within the bending radius (R B ) and wherein, on the other hand, the tongue (19) is of such length that it extends beyond the lower portion (5) into a longitudinal central region (9) provided for the roller (10); D) The wing-shaped protrusion (20) is lifted up to form the side wall (3).

2. A body (1) of an intermediate arm (2) of a variable stroke valve mechanism of an internal combustion engine, the body being manufactured by the manufacturing method according to claim 1, the side wall having an open upper part (4) and a lower part (5) connecting the side walls (3) in a transverse yoke-like manner, the side wall (3) having two holes (6) in the upper part (4), the holes being used either for a shaft (8) carrying at least one supporting roller (7) or for a swingable support on a shaft fixed relative to the cylinder head, wherein The longitudinal center region (9) of the body (1) is configured to arrange a roller (10) for at least indirect relative movement with respect to a cam, wherein, viewed in the direction of arm swing, the lower part (5) extends the body (1) on both sides with legs (11, 12) and has a guide rail (13) on the outside for contacting a valve opener, and wherein, on one of the legs (11), a tongue (19) is sectionally separated from the guide rail (13) and bent toward the upper part (4) as an abutment for a cam return spring.

3. The main body of the intermediate arm according to claim 2, characterized in that: The body (1) has a greater width in the longitudinal central region (9) relative to the lower portion (5).

4. The main body of the intermediate arm according to claim 3, characterized in that: The body (1) has a greater width in the section of the upper part (4) than in its longitudinal center region (9).

5. The main body of the intermediate arm according to claim 2, characterized in that: The tongue (19) extends into the longitudinal center region (9) such that it overlaps with the contour of the roller (10) in sections.

6. The main body of the intermediate arm according to claim 2, characterized in that: The side walls (3) are reinforced in the upper part (4) by transverse yokes (18) which extend in one piece from the side walls and are welded to one another.

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