Shaft, particularly a partly tubular camshaft

Abstract

The invention relates to a shaft, particularly a cam shaft (1), comprising a hollow shaft section (10) with at least one radial inlet opening (11a, 11b) for evacuating a gas through said hollow shaft section (10), and comprising a splash-guard device (4) arranged in the region of the radial inlet opening (11a, 11b) on the hollow shaft section (10). According to the invention, the splash-guard device (4) has a radially exposed cover with radial passage openings (8) and protrusions between said passage openings (8). The protrusions can, in particular, be in the form of ribs (9).

Claims

1. A camshaft comprising: a tubular part extending along and rotatable about an axis and formed with a radial intake port for conducting a gas radially into the radial intake port and axially through the tubular part; a plurality of cams spaced along the tubular part; and a splash guard mounted on the tubular part at the radial intake port between adjacent cams for joint rotation with the tubular part and having a radially outwardly exposed and tubular center section coaxially surrounding the tubular part between the cams and formed with radially throughgoing holes and radially and axially extending ribs between and offset from the holes, the center section of the splash guard and the tubular shaft part forming a radial gap at the intake port, the holes being offset axially or angularly on the tubular shaft part from the intake port for gas flow into the openings, then axially or angularly along the gap around the tubular part, and then radially into the intake port and into the tubular part.

2. The shaft defined in claim 1, wherein the tubular part has a predetermined forward rotation direction, and the ribs are angled and have free ends that extend rearward relative to the predetermined forward rotation direction.

3. The shaft defined in claim 1, wherein the tubular part has a predetermined rotation direction, and a respective one of the ribs is provided upstream of each hole in the rotation direction.

4. The shaft defined in claim 1, wherein the holes are axial slots.

5. The shaft defined in claim 1, wherein the splash guard has radially enlarged ends as viewed axially of the shaft.

6. The shaft defined in claim 5, wherein each of the radially enlarged ends is juxtaposed with a respective one of the cams and the tubular center section extends between the radially enlarged ends.

7. The shaft defined in claim 1, wherein the ribs and the radially throughgoing holes are distributed in a uniform arrangement pair-wise angularly of the center section.

8. The shaft defined in claim 1, further comprising: a bypass valve inside the tubular shaft part.

9. The shaft defined in claim 1, wherein the splash guard is composed of two axially joined segments.

10. The shaft defined in claim 1, wherein the splash guard is bonded with adhesive to the tubular shaft part.

11. The shaft defined in claim 1, wherein the splash guard and the tubular part include interfitting positive-locking elements.

12. The shaft defined in claim 1, wherein the tubular center section is spaced radially outward by the gap from the tubular part.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The following describes the invention based on a drawing that shows only one exemplary embodiment. Therein:

(2) FIG. 1 shows an installation-ready camshaft assembly comprising a camshaft, which module is provided with splash guard;

(3) FIG. 2 is a top view of a section along line A-A in FIG. 1;

(4) FIG. 3 is a perspective view of the section shown in FIG. 2;

(5) FIG. 4 is an axial section through the camshaft at the splash guard.

SPECIFIC DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows an installation-ready camshaft assembly comprising a camshaft 1 with a plurality of cams 2 of typical is construction and mounted in bearing or pillow blocks 3. A splash guard 4 is provided between adjacent cams 2, the function of the splash guard being explained in more detail below.

(7) FIG. 1 shows here that the splash guard 4 is formed by two segments joined at an interface 5. Also shown is the fact that the splash guard 4 has flange-like widened ends 6a and 6b and a tubular, essentially cylindrical center section 7 therebetween. Holes 8 formed as axially extending slots, as well as projections formed as ribs 9 are seen that run axially of the shaft.

(8) The purpose of the splash guard 4 and the exact configuration of the camshaft 1 is shown in FIGS. 2 through 4. FIGS. 2 and 3 are similar cross-sections, the precise orientation of the ribs 9 and of the holes 8 being shown in the end cross-sectional view of FIG. 2. The perspective view of FIG. 3, on the other hand, taken together with FIG. 1, better shows the shape of the ribs 9 and the holes 8 extending axially of the shaft.

(9) The sections first show that the camshaft 1 has a tubular shaft part 10 with at least one intake port—here a total of six radial intake ports 11a and 11b—for conducting blowby gas B through the tubular shaft part 10. The splash guard 4 here prevents large oil droplets or oil streams from being drawn directly into the radial intake ports 11a and 11b.

(10) The ribs 9 and the holes 8 are provided for this purpose. As the camshaft 1 rotates in a predetermined rotation direction D, an angular flow of gas is generated that prevents large oil droplets or even a stream of oil from being drawn in. The blowby gas B, however, can follow the rotation of the camshaft 1 in response to a corresponding overpressure and enter the intake ports 11a and 11b. The path of the blowby gas B is indicated in the cutaway diagrams of FIGS. 2 through 4 by dot-dash lines.

(11) In addition to the fact that a flow of gas is generated by the ribs 9, another factor here is that rotation of the splash guard 4 causes relatively large particles or streams to be deposited on the ribs 9 due to their inertia. FIG. 2 shows in this regard that one rib 9 is provided upstream of each hole 8 as viewed in the rotation direction D. Large oil droplets, splashed oil, and oil streams deposit on the ribs 9 before they can reach the holes 8.

(12) FIG. 2 also shows that the ribs are angled relative to the predetermined rotation direction D so that their free ends point back in the predetermined rotation direction D. The angling can measure, for example, between 10° and 40°, in particular, between 15° and 30° relative to an orientation that runs exactly radially. The angle here measures approximately 25°. The described angle of the ribs 9 first of all enables the hole 8 to be even better protected as its opening is set slightly back from the respective rib 9. In addition, oil that has deposited on the rib 9 is also effectively driven radially outward and finally expelled by centrifugal forces.

(13) The precise construction of the tubular shaft part 10 is seen in FIG. 4. Accordingly, the tubular shaft part 10 has different intake ports 11a and 11b. A radial gap 12 is created between the center section 7 of the splash guard 4 and the tubular shaft part 10, and the blowby gas B flows through this gap 12. Three intake ports 11a lead to an annular region within the tubular shaft part 10 that delivers blowby gas B to an unillustrated swirl generator for oil separation. A bypass valve 13 including a bypass passage 14 connected thereto is provided at the center of the tubular shaft part 10 to allow for rapid removal of the blowby gas in response to excessive overpressure even without cleaning. Blowby gas B from the gap 12 can also reach the bypass valve 13 through the additional intake ports 11b.

(14) FIG. 4 shows that an axial offset is provided between the holes 8 of the splash guard 4 and the first intake ports 11a. Blowby gas B is thus deflected, thereby enabling even larger oil droplets to be separated during their deflection. In particular, there is no straight path along which oil droplets can reach the intake ports 11a.

(15) As indicated in FIG. 2, at least one angular offset is provided for the additional intake ports 11b through which blowby gas B can reach the bypass valve 13. This is achieved by providing the holes 8 and the ribs 9 in groups that each include two of the holes 8 and two of the ribs 9. These six groups are then positioned such that intake ports 11b leading to the bypass valve 13 are exactly between two adjacent groups.

(16) As explained above with reference to FIG. 1, the splash guard 4 is formed by segments, here two axially divided segments here. The interface 5 is seen between the two segments in FIGS. 2 and 3, where the segments can be joined by an adhesive, in particular, a two-component adhesive.

(17) An adhesive can also attach the splash guard 4 to the camshaft 1. Additionally or alternatively, it is also possible to provide interacting positive-locking elements 15 on the splash guard 4 and the tubular shaft part 10, examples of which elements are shown in FIG. 4.