METHOD FOR PRODUCING A CAM PHASER AND CAM PHASER

Abstract

A method for producing a cam phaser for a cam shaft of an internal combustion engine, the cam phaser including a rotor, a stator and at least one cover, the method including arranging the at least one cover at the stator wherein the at least one cover is a flat circular piece of sheet metal and the stator including internal vanes and external drive tooth is integrally provided from one piece of metal; sealing the at least one cover at the stator by applying a ground axial face of the at least one cover to a ground contact surface of the stator; and after the sealing.

Claims

1. A method for producing a cam phaser for a cam shaft of an internal combustion engine, the cam phaser including a rotor, a stator and at least one cover, the method comprising: arranging the at least one cover at the stator wherein the at least one cover is a flat circular piece of sheet metal and the stator including internal vanes and external drive teeth is integrally provided from one piece of metal; contact sealing the at least one cover at the stator by applying a ground axial face of the at least one cover to a ground contact surface of the stator; and after the sealing; welding and externally sealing the at least one cover with the stator by a closed circumferential weld along an outer edge of the at least one cover and connecting the at least one cover to the one piece of metal including the internal vanes and the external drive teeth of the stator while maintaining the contact sealing of the at least one cover at the stator by continuing to apply the ground axial face of the at least one cover to the ground contact surface of the stator.

2. The method according to claim 1, further comprising: performing the welding by laser welding, applying a laser beam to a first joining portion of the at least one cover and melting the first joining portion of the at least one cover into a melted material, and melting a second joining portion of the stator by the melted material from the first joining portion of the at least one cover.

3. The method according to claim 1, wherein a circumferential groove is formed in the at least one cover or the stator before the welding.

4. The method according to claim, further comprising: compressing and condensing an axial face of the stator before grinding so that pore sizes of the ground contact surface of the stator are reduced.

5. A cam phaser for a cam shaft of an internal combustion engine, the cam phaser comprising: a rotor; a stator; and at least one cover, wherein the at least one cover and the stator are produced according to the method according to claim 1.

6. The cam phaser according to claim 4, wherein the at least one cover has a material thickness of less than 6 mm.

7. A cam phaser for a cam shaft of an internal combustion engine, the cam phaser comprising: a rotor; a stator including internal vanes and external drive teeth integrally provided in one piece of metal; and at least one flat circular cover, wherein pressure chambers defined between the stator, the internal vanes and the at least one cover are sealed by applying ground axial contact surfaces of the at least one flat circular cover to ground axial contact surfaces of the stator, and wherein the at least one flat circular cover is externally sealed at the stator by a closed circumferential weld along an outer edge of the at least one flat circular cover so that the closed circumferential weld bonds the at least one flat circular cover to the one piece of metal from which the internal vanes and the external drive teeth of the stator are formed.

8. The cam phaser according to claim 7, wherein the ground axial contact surfaces of the cover include a circumferential surface arranged radially inside the circumferential weld and faces of the internal vanes.

9. The cam phaser according to claim 7, wherein the axial contact surfaces of the stator are compressed and condensed before grinding so that pore sizes of the ground contact surface of the stator are reduced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Further advantages of the invention can be derived from the description and the drawing figures. The invention is subsequently described based on an embodiment with reference to drawing figures, wherein:

[0081] FIG. 1 illustrates a first embodiment of a cam phaser according to the invention produced according to a method according to the invention;

[0082] FIG. 2 illustrates a second embodiment of the cam phaser according to the invention produced according to the method according to the invention;

[0083] FIG. 3 illustrates a view of the cover of the cam phaser according to the second embodiment of FIG. 2;

[0084] FIG. 4 illustrates a view of the stator of the cam phaser of the first and second embodiment;

[0085] FIG. 5 illustrates a view of the cover of the cam phaser according to a third embodiment;

[0086] FIG. 6 illustrates a view of the stator of the cam phaser of the third embodiment;

DETAILED DESCRIPTION OF THE INVENTION

[0087] FIG. 1 illustrates a first embodiment of a cam phaser 100 according to the invention that is produced according to the method according to the invention.

[0088] The cam phaser 100 includes a rotor 110 wherein FIGS. 1 and 2 illustrate only an inner portion of the rotor. The rotor 110 is configured rotatable relative to a stator 120 of the cam phaser 100. The stator 120 of the cam phaser 100 is shown in detail in FIG. 4 and is described in detail with reference to FIG. 4.

[0089] A cover 130 is arranged at the stator 120. The cover 130 is configured disc shaped or circular segment shaped. The cover 130 is configured to cover pressure chambers between the stator 120 and the rotor 110. Thus, a high pressure impacts the cover 130. This pressure can have the effect that surface portions of the cover 130 bulge outward. In order to prevent this the cover 130 is welded with the stator 120 in a special manner. In particular the cover 130 is welded on a small radius 133 and on a large radius 134 with the stator 120 wherein the term radius relates to the cover 130. Thus, a circumferential weld 140 is not only formed at an outer radius of the cover 130 but also further inside.

[0090] The circumferential weld 140 thus includes welds 142 at the small radius 133 and welds 141 at the large radius 134. The large radius 134 corresponds to the outer radius of the cover 130.

[0091] The weld 140 furthermore includes radial weld portions 143 between the welds 141 and the welds 142 wherein the radial weld portions respectively connect a weld 141 on the large radius 134 and a weld 142 on the small radius 133. The radial weld portions 133 thus bridge the radial offset between the welds 141 and the welds 142. Thus, the radial weld portions 143 do not have to be configured exactly in the radial direction. It is sufficient that the radial weld portions facilitate the radius change of the circumferential weld 140.

[0092] Thus, the circumferential weld 140 is configured continuous in FIG. 1, thus without interruption.

[0093] The stator 120 includes plural vanes 121. The vanes 121 extend from an annular body 125 of the stator 120 radially inward. Therefore the vanes 121 are particularly suitable to form the welds 142 on the small radius 133 on the vanes 121. Accordingly the welds 142 in FIG. 1 on the small radius 133 are arranged on the vanes 121.

[0094] FIGS. 1, 2, and 4 illustrate a stator 120 with four vanes 121. The stator 120, however, can also have a different number of vanes 121, for example three or five vanes. Accordingly also another number of welds is conceivable on the small radius 133. Thus, the four welds 142 are formed on the small radius 133. Thus each of the welds 142 is associated with one of the vanes 121. Thus, four welds 141 are also arranged in the portion between the vanes 121.

[0095] The circumferential weld 140 that includes the welds 141, 142 and 143 is configured essentially clover shaped in a radial axial direction of the rotor R. In particular the weld 140 is configured as a four leaf clover. Thus, each individual clover is formed by one of the welds at the large radius 134 and by two adjacent weld portions 143. The individual clover leafs are then connected by one of the welds 142 on the small radius 133.

[0096] FIG. 2 illustrates a second embodiment of the cam phaser 100 according to the invention. The second embodiment has common features with the first embodiment in FIG. 1. These features are not being repeated, however, they are transferable to FIG. 2. In particular the rotor 110 and the stator 120 are configured identical. The description of FIG. 2 therefore does not focus on aspects that differ from the embodiment illustrated in FIG. 1.

[0097] The cover 130 in FIG. 2 is also configured disc shaped, however, not clover shaped. The cover 130 is rather formed annular disc shaped and includes plural recesses 131. The cover 130 is arranged above the stator 120 so that the recesses 131 are respectively arranged above one of the vanes 121. Corresponding to the number of the vanes 121 four recesses 131 are also formed here. It is appreciated that also here another number of vanes 121 and recesses 131 can be formed. In an exemplary manner three, five or six elements can be arranged.

[0098] An inward oriented edge of the recess 131 is arranged on the small radius 133 so that the welds 142 are arranged on the small radius. Also on the opposite edge, thus on the outward oriented edge welds are arranged. Furthermore welds are also formed at radial weld portions 143 between the two edges. Overall also the inner circumference of the recess 131 is connected by a continuous weld with the stator 120. Thus the continuous weld has the shape of the recess 131 in the cross section, this means in the rotation axis direction of the rotor 110. The welds 141 formed on the large radius 134 and the welds 142 formed on the small radius 133 are separate from each other in this embodiment.

[0099] The welds 141 on the large radius 134 are configured in FIG. 2 as a circumferential weld 140. The weld 140 runs along the outer radius of the circular cover 130.

[0100] In an advantageous embodiment shown in FIGS. 5 and 6 the weld 140 is configured as a continuous circumferential weld exclusively on the large radius 134. The vanes 121 are not welded together with the cover 130 in this embodiment. The cover 130 is a flat disk without cut-outs. The sealing of the vales 121 is only provided by applying ground contact surfaces of the cover 130 to ground contact surfaces of the stator 120. The ground contact surfaces of the stator include axial faces of the vanes 121 and a circumferential surface 126 of the stator that is in contact with a ground surface 128 of the cover 130 and arranged radially inside of a circumferential groove 123. Therefore, the cam phaser has a double seal. Externally the cam phaser is sealed by the continuous circumferential weld 140. Internally the pressure chambers defined by the vanes 121 are sealed by the ground axial contact surfaces of the vanes 121, the ground circumferential surface 126 of the stator 120, and the ground contact surface 128 of the cover the cover 130. This provides considerable cost reduction in fabrication since the cover 130 is circular without cut-outs and attached to the stator 120 by a circular weld. Minimal oil seepage between the ground axial contact surfaces of the vanes 121 and the ground surface 128 of the cover 130 is tolerable in view of the fast change of pressure cycles in the cam phaser.

[0101] In an advantageous embodiment the contact surfaces of the stator are compressed end condensed before grinding to reduce pore size.

[0102] Advantageously it is also conceivable to provide a weld 142 exclusively on the small radius 133 or to weld exclusively about the recesses 131.

[0103] FIGS. 1 and 2 illustrate the cam phaser 100 from a side that is oriented away from the cam shaft. A cover 130 configured as described supra can also be arranged from the side oriented towards the cam shaft. Thus, the cover 130 is advantageously configured as a locking plate or locking disc on a side oriented towards the cam shaft, e.g. with a closure flap, whereas the cover 130 is configured as a simple cover plate on a side oriented away from the cam shaft.

[0104] FIG. 3 illustrates the cover 130 of the cam phaser 100 of the second embodiment of FIG. 2. The cover 130 shows the recesses 131 that are configured as openings. Furthermore the cover 130 includes a circumferential groove 132. The circumferential groove 132 runs on a radius adjacent to the large radius 134. Accordingly the groove 132 can support the welding, in particular gasses can be vented.

[0105] FIG. 4 illustrates the stator 120 of the cam phaser 100 in the first and second embodiment. The stator 120 includes four vanes 121 that extend inward from an annular element 125. A continuous opening or bore hole 122 is arranged in each vane 121.

[0106] A circumferential groove 123 is configured at the stator 120. The circumferential groove 123 is formed on the same radius as the circumferential groove 132. Consequently also the radius of the circumferential groove 123 is smaller than the large radius 134. The bore holes 122 are connected through radial grooves 124 with the circumferential groove 123. Thus, gasses can be vented particularly easily. Melted material from the cover 130 can run into the radial groove 124 during welding so that the connection is particularly good.

[0107] All features described and illustrated in a context with individual embodiments of the invention can be provided according to the invention in different combinations while still bringing their advantages to bear. The spirit and scope of the invention is defined by the appended claims and is not limited to the features described in the description or illustrated in the drawing figure.