GB2268547A

GB2268547A - A hollow shaft

Info

Publication number: GB2268547A
Application number: GB9313391A
Authority: GB
Inventors: Gerhard Doll; Mario Murwald; Christoph Reckzugel
Original assignee: Daimler Benz AG; Mercedes Benz AG
Current assignee: Daimler Benz AG
Priority date: 1992-07-02
Filing date: 1993-06-29
Publication date: 1994-01-12
Anticipated expiration: 2013-06-29
Also published as: DE4221708C2; GB2268547B; DE4221708A1; GB9313391D0

Abstract

A hollow shaft 2 for the pivotable support of rocker arms for controlling gas-exchange valves of an internal combustion engine is subdivided into at least two fluid-carrying chambers 5, 6, 7 by an insert profile 4. The chambers are used, in particular, to guide lubricating oil to control valve clearance compensation elements and coupling elements of a valve lift control device. The profile may comprise a tubular outer section 8, or may consist of webs 9, 10 alone, which webs locate in grooves 15-17 in the shaft interior. <IMAGE>

Description

2268547 A hollow shaft The invention relates to a hollow shaft for the

pivotable support of valve actuation levers for controlling gasexchange valves of an internal combustion engine, which shaft is subdivided into at least two fluid- carrying chambers by at least one longitudinal web in the internal space of the shaft.

A shaft, in particular a rocker arm shaft, is known from German Offenlegungsschrift 37 35 156. In this, the longitudinal web is manufactured - together with the rocker arm shaft - from one piece by casting or extrusion, for example.

A disadvantage is that different rocker arm shafts have to be provided for different engine types. This makes the storekeeping more difficult and, in addition, it can easily lead to confusion during assembly. Furthermore, the known rocker arm shaft is not optimised with respect to weight.

The present invention seeks to create a shaft for the pivotable support of valve actuation levers for Controlling gas-exchange valves of an internal combustion engine, which only requires one standard design of shaft for different applications.

According to the present invention there is provided a hollow shaft for the pivotable support of valve actuation levers for controlling gasexchange valves of an internal combustion engine, which shaft is subdivided into at least two fluid-carrying chambers by at least one longitudinal web in the internal space of the shaft, the longitudinal web being manufactured separately from the shaft, wherein the longitudinal web, together with a tube body, forms a component which is inserted as an inner tube into the internal space of the shaft.

According to the invention the hollow shaft for supporting valve actuation levers, also referred to rocker arms, is simply manufactured by inserting a desired insert 2 profile into a conventional tube profile. In this case, it is possible to create rocker arm shaf ts with a dif f erent number of passages in accordance with the selection of the insert profile. In addition, a hollow shaft optimised with respect to weight can be achieved by an appropriate selection of material for the insert prof ile and the tube profile.

Preferably, the inner tube with the longitudinal webs is manufactured by extrusion, and the shaft and the inner tube may consist of different materials. The inner tube may be manufactured from a material with a higher thermal expansion coefficient than the material of the shaft.

The tube body may be provided with a cut-out configured approximately in a V shape and extending in the longitudinal direction in order to form a chamber.

The outer surface of the tube body may be provided with a projecting profiling. The longitudinal web may have an approximately cruciform profile in order to form three or more chambers.

various embadiments of the invention are now explained in more detail in the following description of the drawing, in which:-

Fig. 1 shows, in section, a hollow shaft for supporting valve actuation levers made from a tube profile with an inserted inner tube profiled with longitudinal webs to form chambers; Fig. 2 shows the hollow shaft of Fig. 1 but with a Vshaped cut-out on the inner tube; Fig. 3 shows, in section, a hollow shaft made from a tube profile with a Y-shaped profile inserted in grooves to form three chambers.

1V In the figures, a hollow shaft - for example a rocker arm shaft for supporting the rocker arms (not shown) of an internal combustion engine is indicated by 1. The rocker arm shaft 1 consists, in this case, of a tube profile 2, on which the rocker arms are directly supported, and an insert prof ile 4 inserted in the hollow space 3. In this case, the 3 hollow space 3 is subdivided by the insert profile 4 into, for example, three cnamberE 51 6 and 7, The chdnDer5 5 to 7 are used, in this case, to guide a control f luid, f or example lubricating oil to valve clearance compensation elements or pressurised oil to coupling elements of a variable valve control on the rocker arms.

In Fig. 1, the insert prof ile 4 consists of an inner tube 8 of circular cross-section, whose internal cross-section is subdivided into the three chambers 5, 6 and 7 by a longitudinal web 9, extending within the shell of the inner tube 8, and a longitudinal web 10, branching off from the longitudinal web 9. Knob-type elevations or profiling 11 are provided on the outer periphery of the inner tube 8 and these secure the insert profile 4 pressed into the hollow space 3. In this case, the inner tube with the longitudinal webs 9 and 10 is manufactured by, for example, extrusion and is preferably formed of a material having a greater coefficient of expansion than the tube 2.

In Fig. 2, the insert profile 4 consists of an inner tube 12 with two longitudinal webs 13 and 14 corresponding to Fig. 1, the profile of the inner tube 12 being formed with a channel open towards the outside and bounded by the longitudinal webs 13, 14 in order to form the chamber 7. After the inner tube 12 has been pressed into the tube profile 2, the channel is closed towards the outside by a shell section of the tube profile 2.

The insert profile 4 increases the bending strength, in particular, of the hollow rocker arm shaft 1. Taking account of a specified bending stress, it is therefore possible to reduce the wall thickness of the tube profile 2 so that, despite the insert profile 4, a saving in weight is achieved. This saving in weight is particularly optimum where the insert profile -4 is manufactured from a lightmetal material. It is, of course, also possible to reverse the material combination, i.e. the tube profile 2 consists of a light-metal material and the insert profile 4 consists of an iron or steel material. or both profiles consist of a 4 light-metal material.

According to another aspect of the invention, illustrated in Fig. 3, the insert prof ile 4 consists of a strip which only includes the longitudinal webs 9 and 10 and is directly pressed into the tube prof ile 2. In order to achieve positive positional locking of the strip in this case, grooves 15 to 17 are provided which start from the inner wall of the tube profile and the outer edges of the webs 9 and 10 are held in these grooves.

Claims

Claims

1. A hollow shaft f or the pivotable support of valve actuation levers for controlling gas-exchange valves of an internal combustion engine, which shaft is subdivided into at least two fluid-carrying chambers by at least one longitudinal web in the internal space of the shaft, the longitudinal web being manufactured separately from the shaft, wherein the longitudinal webl together with a tube body, forms a component which is inserted as an inner tube into the internal spacd of the shaft.

2. A hollow shaft according to Claim 1J. wherein the inner tube with the longitudinal webs is manufactured by extrusion.

3. A hollow shaft according to Claim 1, wherein the shaft and the inner tube consist of different materials.

4. A hollow shaft according to Claim 1 or 3, wherein the inner tube is manufactured from a material with a higher thermal expansion coefficient than the material of the shaft.

5. A hollow shaft according to Claim 1, wherein the tube body is provided with a cut-out configured approximately in a V shape and extending in the longitudinal direction in order to form a chamber.

6. A hollow shaft according to Claim 1 and 5, wherein the outer surf ace of the tube body is provided with a projecting profiling.

7. A hollow shaft according to Claim 1, wherein the longitudinal web has an approximately cruciform profile in order to form three or more chambers.

6 A hollow shaft f or the pivotable support of valve actuation levers substantially as described herein with reference to and as illustrated in the accompanying drawings.

-9. A hollow shaft for the pivotable support of valve actuation levers for controlling gas-exchange valves of an internal combustion engine, which shaft is subdivided into at least two fluid-carrying chambers by at least one longitudinal web in the internal space of the shaft, the longitudinal web being manufactured separately from the shaft and being inserted with a force fit into the internal space of the shaft.

10. A hollow shaft according to claim 9, wherein peripheral longitudinal edges of the longitudinal web are located in corresponding grooves in the inner surf ace of the shaft.