Cam shaft for a cam shaft arrangement

Abstract

A cam phaser for a cam shaft arrangement including an inner cam shaft and an outer cam shaft arranged concentrical relative to the inner cam shaft, the cam phaser including at least one rotor; at least one stator; and at least one compensation element configured to compensate axial and/or radial and/or angular tolerances, wherein the stator is connectable torque proof at least indirectly through a drive gear with the outer cam shaft and the rotor is connectable torque proof with the inner cam shaft, wherein the drive gear is separate from the stator and attachable torque proof at the outer cam shaft, wherein the stator is rotatably supportable on the inner cam shaft, wherein plural compensation elements are provided which are arranged evenly distributed in a circumferential direction, wherein the compensation elements are configured torsion stiff in the circumferential direction and attached between the stator and the drive gear.

Claims

1. A cam phaser for a cam shaft arrangement including an inner cam shaft and an outer cam shaft arranged concentrical relative to the inner cam shaft, the cam phaser comprising: at least one rotor; at least one stator; and at least one compensation element configured to compensate axial or radial or angular tolerances, wherein the at least one stator is connectable torque proof at least indirectly through a drive gear with the outer cam shaft and the at least one rotor is connectable torque proof with the inner cam shaft, wherein the drive gear is separate from the at least one stator and attachable torque proof at the outer cam shaft, wherein the at least one stator is rotatably supportable on the inner cam shaft, wherein plural compensation elements are provided which are arranged evenly distributed in a circumferential direction, wherein the compensation elements are configured torsion stiff in the circumferential direction and arranged and attached between the at least one stator and the drive gear that is axially offset from the at least one stator, and wherein the compensation elements are connected form locked or bonded with the at least one stator and the drive gear.

2. A cam phaser for a cam shaft arrangement including an inner cam shaft and an outer cam shaft arranged concentrical relative to the inner cam shaft, the cam phaser comprising: at least one rotor; at least one stator; and at least one compensation element configured to compensate axial or radial or angular tolerances, wherein the at least one stator is connectable torque proof at least indirectly through a drive gear with the outer cam shaft and the at least one rotor is connectable torque proof with the inner cam shaft, wherein the drive gear is separate from the at least one stator and attachable torque proof at the outer cam shaft, wherein the at least one stator is rotatably supportable on the inner cam shaft, wherein plural compensation elements are provided which are arranged evenly distributed in a circumferential direction, wherein the compensation elements are configured torsion stiff in the circumferential direction and arranged and attached between the at least one stator and the drive gear that is axially offset from the at least one stator, and wherein the compensation elements are configured from spring steel.

3. A cam phaser for a cam shaft arrangement including an inner cam shaft and an outer cam shaft arranged concentrical relative to the inner cam shaft, the cam phaser comprising: at least one rotor; at least one stator; and at least one compensation element configured to compensate axial or radial or angular tolerances, wherein the at least one stator is connectable torque proof at least indirectly through a drive gear with the outer cam shaft and the at least one rotor is connectable torque proof with the inner cam shaft, wherein the drive gear is separate from the at least one stator and attachable tome proof at the outer cam shaft, wherein the at least one stator is rotatable supportable on the inner cam shaft, wherein plural compensation elements are provided which are arranged evenly distributed in a circumferential direction, wherein the compensation elements are configured torsion stiff in the circumferential direction and arranged and attached between the at least one stator and the drive gear that is axially offset from the at least one stator, and wherein the compensation elements respectively include a center attachment section provided for attachment at the stator, and wherein the center attachment section is adjoined at an end by a respective outer attachment section for attachment at the drive gear.

4. The cam phaser according to claim 3, the compensation elements are respectively attached at the at least one stator and at the drive gear by a threaded connection.

5. The cam phaser according to claim 3, wherein a respective wave shaped intermediary section is arranged between the center attachment section and the respective outer attachment section.

6. The cam phaser according to claim 3, wherein the center attachment section is attached at a cover element of the stator, and wherein the cover element includes radially configured attachment protrusions configured to arrange the center attachment section.

7. The cam phaser according to claim 6, wherein the attachment protrusions respectively include two first bore holes for attaching the center attachment section, and wherein the two first bore holes are arranged on a first reference circle about the center axis of the cam phaser.

8. The cam phaser according to claim 7, wherein the center attachment section includes two second bore holes for attachment at the cover element and a third bore hole is provided at the respective outer attachment section for attachment at the drive gear, wherein the two second bore holes of the center attachment section and the third borehole of the respective outer attachment section are arranged on a common second reference circle which is identical with the first reference circle.

9. The cam phaser according to claim 3, wherein the at least one rotor is connectable with the inner cam shaft by a central bolt.

10. The cam phaser according to claim 9, wherein the at least one rotor is connectable with the inner cam shaft through a connector by the central bolt.

11. A cam shaft arrangement, comprising: an inner cam shaft; an outer cam shaft arranged concentric to the inner cam shaft; a drive gear attached at the outer cam shaft; and a cam phaser according to claim 3.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages can be derived from the subsequent drawing description. The drawing illustrates embodiments of the invention. The drawing, the description and the claims include numerous features in combination. A person skilled in the art will also view the features the features individually and combine them into additional useful combinations, wherein:

(2) FIG. 1 illustrates a cam shaft arrangement with two coaxial cam shafts, a cam phaser, a drive gear and a compensation element in a sectional view;

(3) FIG. 2 illustrates another embodiment of a cam phaser with a compensation element in a first perspective view;

(4) FIG. 3 illustrates a rear view of the cam phaser according to FIG. 2 in a second perspective view;

(5) FIG. 4 illustrates a rear view of the cam phaser according to FIG. 2;

(6) FIG. 5 illustrates a side view of the cam phaser according to FIG. 2;

(7) FIG. 6 illustrates a front view of the cam phaser according to FIG. 2;

(8) FIG. 7 illustrates a cross section C-C of the cam phaser according to FIG. 2;

(9) FIG. 8 illustrates an exploded view of the cam phaser according to FIG. 2;

(10) FIG. 9 illustrates an enlarged perspective view of the compensation element of the cam phaser according to FIG. 2.

(11) FIG. 10 illustrates a front view of the compensation element according to FIG. 9; and

(12) FIG. 11 illustrates a sectional view along the line A-A of the compensation element according to FIG. 10.

DETAILED DESCRIPTION OF THE INVENTION

(13) FIG. 1 illustrates a detail of a cam shaft arrangement 1 with two coaxial cam shafts 2, 3 a cam phaser 4 and plural compensation elements 5 in a sectional view. The cam shaft arrangement 1 includes an inner cam shaft 2 and an outer cam shaft 3, wherein the inner cam shaft 2 is a solid shaft and the outer cam shaft 3 is a hollow shaft. The inner cam shaft 2 is arranged within the outer cam shaft 3 so that the cam shafts 2, 3 are arranged concentric and coaxial with each other. The cam shafts 2, 3 which can form a central cam shaft for an internal combustion engine respectively include cams and are rotatable relative to each other within limits. The cam shafts 2, 3 can form a central cam shaft for an internal combustion engine. A rotation of the cam shafts 2, 3 relative to each other in this case causes a movement of inlet and outlet timing between early and late. By the same token the cam shafts 2, 3 can form one of two cam shafts for an internal combustion engine. A rotation of the am shafts 2, 3 relative to each other that causes an extension or a shortening of the inlet or outlet control timing.

(14) The cam shafts 2, 3 respectively include an end 6, 7 that is oriented towards the cam phaser 4, wherein the end 6 of the inner cam shaft 2 protrudes towards the cam phaser 4 relative to an end of the outer cam shaft 7.

(15) The cam phaser 4 which is configured as a vane phaser includes a rotor 8 and a stator 9 which are rotatable relative to each other within limits. In the illustrated embodiment the stator 9 includes a cylindrical stator base element 10 and two cover elements 11, 12 that are sealed on the stator base element and attached by bolt elements 34. The stator 9 is at least indirectly connected through a drive gear 13 with the outer cam shaft 3. The drive gear 13 is connected with a non-illustrated crank shaft which forms the drive shaft of the internal combustion engine. For this purpose the drive gear includes an external teething 14. Alternatively the drive gear can be configured as a cog wheel or a sprocket gear. As evident from FIG. 1 the drive gear 13 is connected torque proof with the outer cam shaft 3.

(16) The rotor 8 of the cam phaser 4, however, is connected torque proof with the inner cam shaft 2 which as described supra extends beyond the outer cam shaft 3. In order to connect the rotor 8 with the inner cam shaft 2 a central bolt 15 is provided which is threaded into a bore hole 16 of the inner cam shaft 2. A bolt head 17 of the central bolt 15 thus clamps the rotor 8 with a connection element 18 clamped there between in the axial direction against the end 6 of the inner cam shaft 2. The connector 18 that is rotatably supported in a housing 19 and sealed includes indicated hydraulic channels 20, 21 for controlling the cam phaser 4.

(17) Double cam shaft systems with an inner and outer cam shaft 2, 3 requires improved tolerance compensation compared to systems with a single cam shaft since imprecisions during fabrication and assembly of the two cam shafts 2, 3 relative to each other can lead to binding or increased friction. The cam phaser 4 thus requires small gap tolerances so that tolerance, shape and position deviations can lead to a substantial impairment of the function of the cam shaft arrangements.

(18) In order to compensate for axial and angular tolerances the cam shaft arrangement 1 includes at least plural compensation elements 5 that are evenly distributed in the circumferential direction.

(19) The compensation elements 5 are configured torsion stiff in the circumferential direction and arranged in the axial direction between the drive gear 5 and the cover element 12 of the stator 9 which cover element is arranged on a left side in the drawing figure. Thus, a form locking or bonded attachment (e.g. bolting or welding) is conceivable. An exemplary threaded connection is illustrated between the compensation element 5 and the cover element 12 or the drive gear 13. Thus, the compensation element 5 respectively includes a bolting grommet 22, 23 at its ends wherein the bolting grommet is respectively attached by a bolt element 24, 25 at the cover element 12 or the drive gear 13.

(20) The compensation element 5 is advantageously configured from spring steel which is particularly suitable for providing a flexible connection which allows for the necessary tolerance compensation. By the same token a torque can be safely transmitted without clearance between the drive gear 13 and the cover element 12.

(21) The bolting grommets 22, 23 of the compensation element 5 are connected by a bar 26 whose shape facilitates a separation of the drive gear 13 and the cover element 12 in the axial direction. This separation of cam phaser 4 and drive gear 12 facilitates decoupling the components so that a variable interface is provided which only requires an adaptation of the cover element 5 while the cam phaser 4 remains identical otherwise. The illustrated embodiment includes a bar 26 with a shoulder.

(22) Another embodiment of the invention is illustrated in more detail in FIGS. 2-11. Identical or like components are provided with identical reference numerals. With respect to the general description of the configuration reference is made to the description of the first embodiment.

(23) FIGS. 9-11 thus illustrate one of the identically configured compensation elements 5 in an enlarged representation and partially in a sectional view. It is evident that the compensation element 5 includes a center attachment section that is provided for attachment at the stator 9 and which is respectively adjoined at one end by an outer attachment section 28 for attachment at the drive gear 13. The attachment sections 27, 28 are thus advantageously separated from each other which significantly simplifies assembly.

(24) Between the center attachment section 27 and the outer attachment sections 28 a respective wave shaped intermediary section 29 is provided which has the option to adapt a flexibility of the compensation element 5 to the predetermined properties of a cam phaser 4 by adaptation of the shaft profile.

(25) As evident in particular from FIGS. 2, 3 and 6 the center attachment section is attached at the cover element 12 of the stator 9, the so called locking disc, wherein the cover element 12 includes radially configured attachment protrusions 30 for arranging the center attachment section 27. The attachment protrusions 30 facilitate simple assembly of the compensation elements 5. This applies in particular for the attachment of the compensation elements 5 at the locking disc and for the attachment at the non-illustrated drive gear 13. The intermediate sections 29 and the outer attachment sections extend beyond the attachment protrusions 30 and respectively extend in different circumferential directions after being mounted at the stator 9 which is evident in particular from FIG. 6.

(26) In order to compensate axial and angular tolerances the cam phaser 4 according to the second embodiment includes three compensation elements 5 that are evenly distributed in the circumferential direction. An even distribution of only two or more than more than three compensation elements 5 is also conceivable. Thus, the arrangement of the compensation elements 5 influences force flow during torque transmission.

(27) The attachment protrusions 30 of the locking disc respectively include 2 bore holes 31 for attaching the center attachment sections 27 which are arranged on a first reference circle K1 about the center axis M of the cam phaser 4 illustrated in FIG. 4.

(28) By the same token the center attachment section 27 respectively includes two corresponding bore holes 32 for attachment at the cover element 12 and a respective bore hole 33 is attached at the outer attachment section 28 for attachment at the drive gear 13 wherein the bore holes 32 of the center attachment section 27 and the bore holes 33 of the outer attachment section 28 are arranged on a common second reference circle K2 which is identical with the first reference circle K1. Thus force flow can be optimized during torque transmission between the drive gear 13 and the stator 9.