Actuating device of a recirculation pump for a cooling circuit of an internal combustion engine

1. An actuating device for a recirculation pump of a cooling circuit of an internal combustion engine comprising a driving member having a rotation axis (A) and adapted to be rotatably driven by the internal combustion engine, a driven member for driving said pump and an electromagnetically controlled coupling interposed between the driving member and the driven member, in which the coupling comprises an electromagnet, a coupling mechanism controlled by said electromagnet and movable between an engagement position in which said driving member is connected to said driven member and a disengagement position, and an elastic member maintaining said coupling mechanism in said engagement position when said electromagnet is not energized.

2. The device according to claim 1 , wherein the electromagnet comprises a coil and a mobile armature.

3. The device according to claim 2 , wherein the elastic member acts on said mobile armature in opposition with said coil.

4. The device according to claim 2 , wherein the armature is rotationally rigidly connected to one of said driving member or driven member, said coupling member comprising a friction element rigidly connected to said armature and adapted to cooperate with the other of said driving member or driven member.

5. The device according to claim 4 , wherein said armature is rotationally rigidly connected to said driven member via said elastic member.

6. The device according to claim 5 , wherein said friction element is a friction disk carried by said armature and adapted to cooperate frontally with said driving member.

7. The device according to claim 6 , wherein said elastic member comprises a diaphragm spring connecting the armature to a supporting element rigidly connected to said driven member.

8. device according to claim 1 , wherein said coupling member comprises a band spring wound partially on a first element rigid with the driving member and partially on a second element rigid with said driven member, said band spring exerting an elastic tightening action such as to rotationally constrain said first and second element together.

9. The device according to claim 8 , wherein said elastic member comprises a second spring coaxial with said band spring and interposed between said armature and said second element, said band spring having one end fastened to said second element and one end fastened to said armature, so that the action of said coil on said armature produces a shift such as to deform the band spring and disengage it from said first element.

10. The device according to claim 8 , wherein said band spring has an end fastened to said second element and a second free end; said armature being movable between a position of disengagement of said second end of the band spring and a position of engagement with said second end of the band spring, the engagement between said armature and said second end of the band spring determining a torsional load on said band spring such as to disengage it from said first element.

11. The device according to claim 10 , wherein said armature is a diaphragm spring having an outer portion fastened to a support of said electromagnet and an inner portion forming an appendix adapted to cooperate with said second end of said band spring.

12. The device according to claim 6 , further comprising a hub element is rigidly connected to said driven member, and said armature is rotationally fixed to, but axiall slidable on, said hub element.

13. The device according to claim 12 , wherein said elastic member is carried by said hub element.

14. The device according to claim 13 , wherein said armature is coupled to said hub element by a spline.

15. The device according to claim 12 , wherein said hub element has front teeth, said armature having an internal spline defined by a plurality of radial projections spaced by cavities that are slidingly engaged by said front teeth of said hub element.

16. The device according to claim 15 , wherein said elastic member include a plurality of springs compressed between said hub element and said armature.

17. The device according to claim 16 , wherein said support element is cup shaped and has a cylindrical wall provided with said front teeth, said springs being located each between two adjacent teeth of said hub element and cooperating with a respective radial projection of said armature.

18. The device according to claim 17 , wherein said springs are partially housed within respective blind holes of said cylindrical wall of said hub element.

19. The device according to claim 1 , wherein said driving member is a pulley and that said coupling mechanism is contained in a cavity adjacent said pulley.

20. The device according to claim 1 , wherein said driven member is an input shaft of said pump.