BEAM-LIKE CROSSHEAD FOR A VALVE TRAIN OF A HEAVY-DUTY INTERNAL COMBUSTION ENGINE

Abstract

A beam-like crosshead for a valve train of an internal combustion engine is proposed for the transmission of a cam lift to two gas exchange valves. The crosshead has two side walls which are connected by a transverse wall, and, on an upper side of the transverse wall at its longitudinal center, a contact surface for a cam follower, and, on an underside of the transverse wall at each of its longitudinal ends, a valve contact surface. The crosshead is a reversed bowl-like hollow body which is produced from steel sheet using stamping/bending technology. From the transverse wall the side walls and, transversely at each longitudinal end, end walls hang in a finger-like manner. Cut edges between the side and end walls, starting from the transverse wall, form cut-outs.

Description

TECHNICAL FIELD

The disclosure relates to a beam-like crosshead for a valve train of a heavy-duty internal combustion engine for the transmission of a cam lift to two identically acting gas exchange valves.

BACKGROUND

A generic crosshead emerges from DE 10 2010 011 455 A1. This is designed as a solid part using casting or forging technology.

Another crosshead, here with hydraulic lash adjuster elements, is disclosed in DE 10 2015 211 124 A1.

A “heavy-duty internal combustion engine” is to be understood as a machine such as is used in particular to drive a truck, van, light transporter, agricultural implement, ship, mining or construction site equipment, etc.

SUMMARY

The object is to create a crosshead as mentioned above that is inexpensive and easy to build.

According to the disclosure, this object is achieved in that the crosshead is a reversed bowl-like hollow body which is produced from steel sheet using stamping/bending technology. From the transverse wall thereof, side walls and, transversely at each longitudinal end, end walls hang in a finger-like manner. The end walls either have a course which is planar or is bulged in a half ring-like manner. There are cut edges between the side and end walls, starting from the transverse wall, with the respective cut edges forming cut-outs.

Thus, there is a crosshead that can be achieved inexpensively by punching and bending, especially for an application in a valve train of a commercial vehicle internal combustion engine or another heavy-duty work machine, which has the required rigidity. Alternatively, the hollow crosshead body can also be extruded or embossed-extruded.

As the end walls are separated from the side walls, comparatively little stress can be expected in the bent material. Inner surfaces of the end walls, along with adjacent inner surfaces of the side walls, serve as a valve stem guide. By varying the cutting height between the side and end walls, differently spaced bending edges can be achieved for the end walls on the transverse wall, so that the crosshead can be adapted to different valve spacings with otherwise the same dimensions, or the end walls can have a different height than the area of the adjacent side walls.

According to a further development of the disclosure, the crosshead can have a wall thickness in the range from 2-10 mm. For a range between approximately 3 and 6 mm, thick sheet metal is used.

Compared to cast or forged variants according to the prior art, the necessary reworking of the contact surface on the upper side and the valve contact surfaces on the underside is no longer necessary or is noticeably reduced.

As already mentioned, the cold-formed crosshead can be installed without any further mechanical post-processing. Alternatively, at least one of their functional surfaces mentioned in the last paragraph can be coined, so that the surface quality is improved here and/or one of these surfaces can be slightly crowned so that edge loading or the like is avoided during use.

The inverted bowl-like structure of the crosshead according to the disclosure, which thus has an inverted U-profile in cross-section, gives it the necessary rigidity with comparatively little material usage. The crosshead itself, which is now comparatively intricate with regard to its specific use, and this is also an essential feature of the disclosure, rests “freely” on the valve stems without any further components. There are no cross-members connected to the cylinder head to guide them or anything similar.

According to a further development of the disclosure, the end walls of the crosshead can either be shaped like a half ring or also be smooth-walled and straight.

The “hollow” crosshead can be present as a simple rectangular or elongated hole cup, the raised cut edges of which are open and unconnected between the side and end walls, as explained. The middle section of the crosshead can also be raised in a roof-like manner, which under certain circumstances gives it more rigidity and/or is a requirement for the necessary installation conditions.

The crosshead has a simplified geometry when the “lower”, free edge of the side walls is completely flat. This also facilitates its handling and transport. Alternatively, this edge can be arched in the central area, which leads to greater side wall height and thus to improved rigidity.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a spatial view of the crosshead from above, and

FIG. 2 shows the crosshead as mentioned above in a view from below.

DETAILED DESCRIPTION

The figures disclose a beam-like crosshead 1 for a valve drive of a heavy-duty internal combustion engine, produced from thick-walled steel sheet (4-6 mm) using stamping/bending technology. The crosshead 1 is used to transmit a cam lift to two identically acting gas exchange valves that are located therebelow.

The inverted bowl-like, hollow crosshead 1 has two side walls 3 connected by an “overhead” transverse wall 2. On an upper side 4 of the transverse wall 2, at a longitudinal center of the crosshead 1, there is a flat and coined contact surface 5 for a rocker arm. On an underside 6 of the transverse wall 2, at each of its longitudinal ends 7, the crosshead 1 has a re-stamped or coined valve contact surface 8.

It can be seen that end walls 9 hang on the transverse wall 2 in a finger-like manner. These are designed separately from the side walls 3, wherein cut-outs 11 are present in the area of “upright” cut edges 10 between the side and end walls 3, 9, starting from the transverse wall 2. The end walls 9 have an approximately planar course and can be bent separately to form the side walls 3 when the final shape of the crosshead 1 is shown.

FIG. 2 best shows that the crosshead 1, seen in a side view and starting from both longitudinal ends 7, consists of a plateau 12 on each transverse wall 2, on the respective underside 6 of which the valve contact surface 8 is located. In the direction of the longitudinal center, the plateaus 12 each continue in a roof-like rising section 13, which sections 13 end in front of the longitudinal center and are connected via a flat piece 14 having the contact surface 5 on the upper side 4.

As finally shown in FIG. 1, a free edge 16 of the side walls 3 facing away from the transverse wall 4 is provided with a stiffness-increasing elevation 17 in the region of the longitudinal center. Areas of the edge 16 opposite the plateaus 12, on the other hand, are planar and run approximately parallel to the plateaus 12.

LIST OF REFERENCE CHARACTERS

1) Crosshead

2) Transverse wall

3) Side wall

4) Upper side

5) Contact surface

6) Underside

7) Longitudinal end

8) Valve contact surface

9) End wall

10) Cut edge

11) Cut-out

12) Plateau

13) Section

14) Flat piece

15) Embossing

16) Edge

17) Elevation

Claims

1. A crosshead for a valve train of an internal combustion engine for a transmission of a cam lift to two gas exchange valves, the crosshead comprising: a body forming an inverted U-shape cross-sectional profile via bending of steel sheet, the body having: a first side wall connected to a second side wall via a transverse wall,a contact surface configured to engage a rocker arm or a camshaft, the contact surface formed on an upper side of the transverse wall, anda first valve contact surface and a second valve contact surface formed on an underside of the transverse wall,a first end wall configured as a first finger extending from a first longitudinal end of the transverse wall, and a second end wall configured as a second finger extending from a second longitudinal end of the transverse wall, andthe first end wall is cut and separated from the first and second side walls such that first respective cut edges of the first end wall and the first and second side walls form first and second cut-outs, andthe second end wall cut and separated from the first and second side walls such that respective second cut edges of the second end wall and the first and second side walls form third and fourth cut-outs.

2. The crosshead of claim 1, wherein the crosshead has a wall thickness of 2-10 mm.

3. The crosshead of claim 1, wherein the transverse wall includes a first plateau, a second plateau, a first rising section, a second rising section, and a longitudinal center section, and the first valve contact surface is formed on the first plateau,the second valve contact surface is formed on the second plateau,the contact surface is formed on the longitudinal center section,the first plateau is connected to the longitudinal center section via the first rising section such that a first elevation of the first plateau is different than an elevation of the longitudinal center section, andthe second plateau is connected to the longitudinal center section via the second rising section such that a second elevation of the second plateau is different than the elevation of the longitudinal center section.

4. The crosshead of claim 1, wherein at least one of the contact surface or the first and second valve contact surfaces are formed via a coining process.

5. The crosshead of claim 1, wherein the first and second side walls each define a respective first free edge and a second free edge, the first and second free edges facing away from the transverse wall, and at least a portion of the first and second free edges has a constant elevation.

6. The crosshead of claim 5, wherein the first, second, third, and fourth cut-outs extend from the transverse wall.

7. The crosshead of claim 1, wherein the first and second end walls are formed via bending of sheet steel.

8. The crosshead of claim 1, wherein the first and second end walls, the first and second side walls, and the transverse wall form an inverted bowl.

9. The crosshead of claim 8, wherein the first end wall is arranged directly adjacent to the first valve contact surface, and the second end wall is arranged directly adjacent to the second valve contact surface.

10. The crosshead of claim 8, wherein the first and second end walls extend orthogonally relative to the contact surface.

11. The crosshead of claim 3, wherein the first and second end walls extend orthogonally relative to the longitudinal center section.

12. A crosshead for a valve train of an internal combustion engine for a transmission of cam lift to two gas exchange valves, the crosshead comprising: a body forming an inverted U-shape cross-sectional profile via cutting and bending of a single piece of sheet steel, the body having:a transverse wall having: an upper side formed with a contact surface configured to engage a rocker arm or a camshaft,an underside formed with a first valve contact surface and a second valve contact surface,a first side wall extending in a first direction from a first longitudinal side of the transverse wall,a second side wall extending in the first direction from a second longitudinal side of the transverse wall,a first end wall cut and separated from the first and second side walls, the first end wall extending in the first direction from a first longitudinal end of the transverse wall, anda second end wall cut and separated from the first and second side walls, the second end wall extending in the first direction from a second longitudinal end of the transverse wall.

13. The crosshead of claim 12, wherein the first end wall is directly adjacent to the first valve contact surface, and the second end wall is directly adjacent to the second valve contact surface.

14. The crosshead of claim 12, wherein first respective cut edges of the first end wall and the first and second side walls form first and second cut-outs, and second respective cut edges of the second end wall and the first and second side walls form third and fourth cut-outs.

15. The crosshead of claim 14, wherein the first, second, third, and fourth cut-outs extend from the transverse wall.

16. The crosshead of claim 12, wherein the transverse wall further comprises a first plateau and a second plateau, and the first valve contact surface is formed on the first plateau, and the second valve contact surface is formed on the second plateau.

17. The crosshead of claim 16, wherein the transverse wall further comprises a longitudinal center section, and the contact surface is formed on the longitudinal center section.

18. The crosshead of claim 17, wherein the transverse wall further comprises a first rising section and a second rising section and, the first plateau is connected to the longitudinal center section via the first rising section such that a first elevation of the first plateau is different than an elevation of the longitudinal center section, andthe second plateau is connected to the longitudinal center section via the second rising section such that a second elevation of the second plateau is different than the elevation of the longitudinal center section.