CENTRAL ACTUATOR FOR CAM PHASER

Abstract

A central actuator for a magnet valve of a cam phaser, the central actuator including a housing that envelops the central actuator; a pole tube and a pole core that are arranged within at least one coil that generates a magnetic field; an actuation plunger that is arranged at an armature that is axially movable in a direction in an armature cavity; a closure element that closes the armature cavity, wherein the closure element includes at least one pole core insert that includes a central bore hole and a support bushing that is arranged in the central bore hole of the pole core insert, wherein the actuation plunger is supported axially movable in the support bushing, and wherein the closure element includes a closure cover and is provided as a pre-assembled module.

Claims

1. A central actuator for a magnet valve of a cam phaser, the central actuator comprising: a housing that envelops the central actuator; a pole tube and a pole core that are arranged within at least one coil that generates a magnetic field; an actuation plunger that is arranged at an armature that is axially movable in a direction in an armature cavity; a closure element that closes the armature cavity, wherein the closure element includes at least one pole core insert that includes a central bore hole and a support bushing that is arranged in the central bore hole of the pole core insert, wherein the actuation plunger is supported axially movable in the support bushing, and wherein the closure element includes a closure cover and is provided as a pre-assembled module.

2. The central actuator according to claim 1, wherein the closure cover includes a central bore hole in which the support bushing is arranged.

3. The central actuator according to claim 2, wherein the support bushing is produced by a plastic injection molding method and the closure cover and the pole core insert are encased through injection molding by the material of the support bushing in a portion of the central bore hole of the pole core insert and in a portion of the central bore hole of the closure cover.

4. The central actuator according to claim 1, wherein the support bushing includes recesses that are arranged in the axial direction and provide a pressure compensation between the armature cavity and an outer space of the central actuator.

5. The central actuator according to claim 1, wherein the support bushing includes a shoulder on a side that is oriented towards the armature that provided a stop for the armature and limits an axial movement of the armature.

6. The central actuator according to claim 1, wherein the actuation plunger is pressable into a central bore hole of the armature.

7. The central actuator according to claim 1, wherein the actuation plunger is made from a soft magnetic material.

8. The central actuator according to claim 1, wherein the actuation plunger includes at least one transversal bore hole between the armature and the support bushing, wherein the at least one transversal bore hole provides a pressure compensation between a front side and a back side of the armature, and wherein the at least one transversal bore hole leads into a central longitudinal bore hole that leads into the central bore hole of the armature.

9. The central actuator according to claim 1, wherein the actuation plunger includes flat areas which extend on both sides beyond a press in portion of the central bore hole, and wherein the central bore hole is configured with at least one shoulder and includes an enlarged inner diameter that starts in the portion of the flat areas.

10. The central actuator according to claim 1, wherein the actuation plunger and the armature are provided integral in one piece.

11. The central actuator according to claim 1, wherein the armature is movably supported in a nonmagnetic sleeve in an axial direction oriented towards the pole core insert.

12. The central actuator according to claims 1, wherein the pole tube and the pole core are configured integral in one piece and the armature is supported axially movable in the pole tube and in the pole core in a direction oriented towards the pole core insert.

13. The central actuator according to claim 1, wherein the armature includes a diameter shoulder configured as a support surface at an end of the armature that is oriented towards the closure element, and wherein the support surface provides support in the armature cavity.

14. The central actuator according to claim 13, wherein the support surface of the armature is configured polygonal and includes flat areas that are uniformly spaced in a circumferential direction and provide pressure compensation between a front side and a back side of the armature.

15. The central actuator according to claim 13, wherein the support surface of the armature is provided as a cylindrical diameter shoulder with an enlarged exterior diameter.

16. The central actuator according to claim 1, wherein the housing is produced by a plastic injection molding method.

17. The central actuator according to claim 16, wherein the closure cover is attached at the housing by ultra sound riveting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further advantages of the invention can be derived from the subsequent drawing description. The drawing figures schematically illustrate an embodiments of the invention. The drawing figures, the description and the patent claims include numerous features in combination. A person skilled in the art will advantageously also view the features individually and combine them into useful additional combinations, wherein:

[0030] FIG. 1 illustrates a sectional view through a central actuator according to a first embodiment of the invention;

[0031] FIG. 2 illustrates a sectional view through the closure element of the central actuator according to FIG. 1;

[0032] FIG. 3 illustrates a sectional view of a central actuator according to a second embodiment of the invention;

[0033] FIG. 4 illustrates an armature according to the second embodiment according to FIG. 3;

[0034] FIG. 5 illustrates a sectional view through a central actuator according to a third embodiment of the invention; and

[0035] FIG. 6 illustrates an enlarged view of the armature with the actuation plunger according to the third embodiment according to FIG. 5 pressed in.

DETAILED DESCRIPTION OF THE INVENTION

[0036] In the drawing figures identical or like components are designated with identical reference numerals. The figures merely illustrate embodiments and do not limit the spirit and scope of the invention.

[0037] FIG. 1 illustrates a sectional view of a central actuator 10 according to a first embodiment of the invention. The central actuator 10, that is configured in particular for a magnet valve of a cam phaser thus includes a pole tube 12 that is arranged within a cylindrical coil 52 that forms a magnet field and a housing 46 which envelops the central actuator 10. The housing 46 is produced by a plastic injection molding method so that it can be produced in a cost effective manner by inserting the various components of a pole yoke 50 during the injection molding process to provide the closed magnetic flux.

[0038] Furthermore the central actuator 10 includes a closure element 18 that is illustrated in FIG. 2 in a blown up view and which closes the housing 46 wherein the closure element 18 includes a pole core insert 22 with a central bore hole 24 and a support bushing 26 that is arranged in the central bore hole 24 of the pole core insert 22.

[0039] Furthermore the closure element includes a closure plate 42 and the closure element is provided as a pre assemble able module.

[0040] The closure cover 42 is attached at the housing 46 for example by ultra sound riveting. For this purpose the housing 46 has an ultra sound geometry configured with plural protrusions 42 which penetrate through bore holes 64 of the closure cover 42, The protrusions 62 are melted and deformed by the ultra sound riveting so that the closure cover 42 is safely attached at the housing 46.

[0041] As evident in particular from FIG. 2 the closure cover 42 includes a central bore hole 43 in which the support bushing 26 is arranged.

[0042] Advantageously the support bushing 26 is produced by a plastic injection molding method and the closure cover 42 and the pole core insert 22 are provided as inserts which are inserted into the injection molding tool when producing the support bushing 26 and the inserts are encased through injection molding by the material of the support bushing in a portion of central bore holes 24, 43 of the inserts. This provides a permanent sealing of the support bushing 26 against the pole core insert 22 and the closure cover 42.

[0043] An actuation plunger 20 is arranged at an armature 28 which is movably supported in an axial direction L oriented towards the pole core insert 22 within an armature cavity 60. The actuation plunger is supported axially moveable in the support bushing 26 whereas the armature 28 is supported in a non-magnetic sleeve 29. The non-magnetic sleeve 29 is supported in the pole tube 12 and in a pole core 14. It is evident that the sleeve 29 extends up to an end of an armature cavity 60 that is closed by the closure cover 42 and has a continuous inner diameter in an entire operating range that is traveled by the armature 28 so that the armature 28 can be supported over its entire length. This assures furthermore that the armature 28 cannot wedge at a slant angle which would otherwise lead to high radial forces upon the armature 28 and thus to a high friction relative to the pole tube 12. Sealing the sleeve 29 is performed by an annular seal element 56 which is arranged between a shoulder 58 of the sleeve 29 and the housing 46 and which contacts the closure cover 42 and a portion of the pole yoke 50 in a sealing manner.

[0044] According to a non-illustrated embodiment the pole tube 12 and the pole core 14 can be produced integrally in one piece. Thus, the sleeve 29 can be omitted in this case and the armature 28 is configured axially movable in a direction oriented towards the pole core insert.

[0045] The support bushing 26 includes axially arranged recesses 32 to provide a pressure compensation between the armature cavity 60 and an outer space 54 of the central actuator 10. The pressure compensation provides a volume compensation of the enclosed hydraulic fluid or of the enclosed air between the armature cavity 60 and an exterior space of the central actuator 10. A pressure compensation of this type is important for dry operations, thus an air filled armature cavity 60 as well as for operations with hydraulic fluid in the armature cavity 60.

[0046] The support bushing 26 includes a shoulder 40 configured as a stop of the armature 28 at a side of the support bushing 26 that is oriented towards the armature 28 during an axial movement of the armature 28. A fixed stop of this type keeps the face of the armature 28 at a certain distance from the disc shaped pole core insert 22 and thus prevents a sticking of the armature 28 with the face of the armature 28 at the pole core insert 22. A sticking would change the movement properties of the armature 28 and significantly influence magnetic forces required to operate the armature 28 so that the entire dynamic properties of the central actuator 10 would thus be changed. Therefore the shoulder 40 configured as an anti-stick disc can positively influence the dynamic properties and the energy consumption of a central actuator 10 that is operated by magnetic forces.

[0047] The actuation plunger 20 is pressable into a central bore hole 30 of the armature 28. When the actuation plunger 20 is made from a different material than the armature 28 this provides an advantageous solution for connecting both components. The pole yoke 50 which can be configured from plural plates and/or tubes envelops the coil 52 on its outsides wherein the coil 52 is completely enveloped by magnetic material since the pole tube 12 is configured in an interior of the coil 52. Thus, the magnetic flux generated by the coil 52 is advantageously focused upon the volume portion in which the armature 28 can move.

[0048] This facilitates a pressure compensation between a front side and a back side of the armature 28 in that the actuation plunger 20 includes one or plural transversal bore holes 71 which lead into a central longitudinal bore hole 72 leading into the bore hole 30 of the armature 28 so that the armature 28 is loaded with the same hydraulic pressure on both sides.

[0049] The armature 28 can furthermore be supported by a two point support as will be described with reference to a subsequent embodiment.

[0050] FIG. 3 illustrates a sectional view through a central actuator 10 according to a second embodiment of the invention. This differs from the first embodiment only in that the armature 28′ and the actuation plunger 20′ are produced integrally in one piece. The two components illustrated in FIG. 4 are thus made from the same material and the actuation plunger 20′ can be made from a soft magnetic material like the armature 28′. Thus, a central actuator 10′ can be constructed that is very compact.

[0051] A support surface 66 at an end of the armature 28′ that is oriented away from the closure element 18 can be configured polygonal as a diameter shoulder 75 and includes flat areas 68 that are uniformly spaced in a circumferential direction wherein the flat areas facilitate a pressure compensation between the front side and back side of the armature 28′.

[0052] The diameter shoulder 75 operating as a support surface 66 forms a first bearing location of the armature 28′. The support of the actuation pin 20′ in a stepped recess 70 of the support bushing 26 is used as a second support for the armature 28′ which is illustrated in particular in FIG. 2. This two point support with large bearing distance facilitates good support for the armature 28′ since small coaxial errors from an outer diameter of the pole core insert 22 to an inner diameter of the support bushing 26 and from an armature outer diameter and a plunger outer diameter can be compensated.

[0053] FIGS. 5 and 6 illustrate another embodiment of the invention which differs from the first embodiment essentially by a configuration of the pressure compensation between the front side and the back side of the armature 28″.

[0054] As also described with respect to the first embodiment the actuation plunger 20″ is pressed into a central bore hole 30″ of the armature 28″. Differently therefrom the essentially cylindrical actuation plunger 20″ includes flat areas 73 in the press in portion wherein the flat areas are for example milled or fabricated through eccentrical turning in order to provide a volume or pressure compensation between a front side and a back side of the armature 28″. The illustrated embodiment includes three flat areas 73 that are distributed over the circumference.

[0055] As illustrated in particular from FIG. 6 which illustrates the armature 28″ with the pressed in actuation plunger 20″ in a blown up sectional view the flat areas 73 extend on both sides beyond the press in portion of the bore hole 30″.

[0056] In order to configure the actuation plunger 20″ without points and thus facilitate a cost effective production the flat areas 73 do not extend to an end 74 of the actuation plunger 20″. The bore hole 30″ is configured with shoulders and includes an inner diameter that is increased and starts in a portion of the flat areas 73 in order to facilitate a volume compensation through the flat spots 73 and the end 74. This allows omitting axial bore holes in the armature 28″ or longitudinal flat spots at the outside of the armature 28″ which would be expensive to fabricate at the armature and which impact the magnetic force negatively.

[0057] In order to provide the described advantageous two point support the armature 28″ includes a cylindrical diameter shoulder 75″ in an end portion wherein the diameter shoulder forms the support surface 66″ with an enlarged outer diameter.

REFERENCE NUMERALS AND DESIGNATIONS

[0058] 10, 10′, 10″ central actuator

[0059] 12 pole tube

[0060] 14 pole core

[0061] 18 closure element

[0062] 20, 20′, 20″ actuation plunger

[0063] 22 pole core insert

[0064] 24 bore hole

[0065] 26 support bushing

[0066] 28, 28′, 28″ armature

[0067] 29 sleeve

[0068] 30, 30″ bore hole

[0069] 32 recess

[0070] 40 shoulder

[0071] 42 closure cover

[0072] 43 bore hole

[0073] 46 housing

[0074] 50 pole yoke

[0075] 52 coil

[0076] 54 outer space

[0077] 56 seal element

[0078] 58 shoulder

[0079] 60 armature cavity

[0080] 62 protrusion

[0081] 64 bore hole

[0082] 66, 60″ support surface

[0083] 68 flat area

[0084] 70 recess

[0085] 71 transversal bore hole

[0086] 72 longitudinal bore hole

[0087] 73 flat area

[0088] 74 end

[0089] 75, 75″ diameter shoulder

[0090] L direction