Electromagnetic control device, in particular for adjusting camshafts of an internal combustion engine

Abstract

The application relates to an electromagnetic control device, in particular for adjusting camshafts or a camshaft section of an internal combustion engine, comprising: an energizable coil unit, via which, in an energized state, an armature mounted for movement along a longitudinal axis of the control device can be moved relative to a pole core between a retracted position and an extended position; at least one tappet, which is mounted for movement along the longitudinal axis and, in an extended position, interacts with the camshaft via a free end in order to adjust the camshaft and is connected at an inner end to the armature, wherein the tappet has a first diameter in the region of the free end and has a second diameter in the region of the inner end, and the first diameter is greater than the second diameter.

Claims

1. An electromagnetic control device, comprising: an armature; an energizable coil unit, with which, in the energized state, the armature is mounted for movement along a longitudinal axis of the control device and is movable between a retracted position and an extended position; a tappet, which is mounted for movement along the longitudinal axis and, in the extended position, interacts with a camshaft via a tappet free end in order to adjust the camshaft and is connected at a tappet inner end to the armature; wherein the tappet has a first diameter in a region of the tappet free end and has a second diameter in a region of the tappet inner end; wherein the first diameter is greater than the second diameter; and further comprising an adapter with which the control device can be fastened to a component, wherein the adapter forms a first bearing section for rotatably mounting the tappet in the adapter, wherein the tappet, in the region of the tappet free end, has a bearing surface which interacts with the first bearing section, wherein the tappet, between the region of the tappet free end and the region of the tappet inner end, comprises another region having a third diameter, wherein the third diameter is smaller than the first diameter, wherein the tappet, between the tappet free end and the bearing surface, has a fourth diameter which is smaller than the first diameter.

2. The electromagnetic control device according to claim 1, wherein the tappet forms an offset at a transition from the first diameter to the fourth diameter.

3. The electromagnetic control device according to claim 1, further comprising a second bearing section for rotatably mounting the tappet outside the armature.

4. The electromagnetic control device according to claim 1, wherein the tappet is stainless steel.

5. A device, comprising: a housing having a longitudinal axis; a biasing spring that acts along the longitudinal axis; an energizable coil unit located in the housing; a tappet that extends along the longitudinal axis and comprises: a tappet free end for interaction with a camshaft; a tappet armature end that connects to an armature; a tappet adapter section located exterior to the housing, wherein the tappet adapter section has a first diameter; a tappet armature section located within the housing and having a second diameter; a tappet middle section located between the tappet adapter section and the tappet armature section, wherein the tappet middle section has a third diameter; a tappet offset section located proximate to the tappet adapter section, wherein the tappet offset section has a fourth diameter; wherein the first diameter is greater than the second diameter; and wherein the tappet is rotatably mounted such that rotation of the tappet is not transferred to the spring.

6. The device according to claim 5, wherein the third diameter is smaller than the first diameter.

7. The device according to claim 5, further comprising: an adapter extending from the housing and having a first bearing section for movably mounting the tappet, wherein the first bearing section is located in the adapter and outside of the housing, and wherein the first bearing section extends along the tappet adapter section.

8. The device according to claim 7, wherein the tappet offset section extends beyond the adapter.

9. An electromagnetic control device, comprising: an armature; an energizable coil unit, with which, in the energized state, the armature is mounted for movement along a longitudinal axis of the control device and is movable between a retracted position and an extended position; a tappet, which is mounted for movement along the longitudinal axis and, in the extended position, interacts with a camshaft via a tappet free end in order to adjust the camshaft and is connected at a tappet inner end to the armature; wherein the tappet has a first diameter in a region of the tappet free end and has a second diameter in a region of the tappet inner end, and wherein the first diameter is greater than the second diameter, further comprising an adapter with which the control device can be fastened to a component, wherein the adapter forms a first bearing section for rotatably mounting the tappet in the adapter, wherein the tappet, in the region of the tappet free end, has a bearing surface which interacts with the first bearing section, wherein the tappet, between the tappet free end and the bearing surface, has a fourth diameter which is smaller than the first diameter, further comprising a second bearing section for rotatably mounting the tappet outside the armature.

10. An electromagnetic control device, comprising: an armature; an energizable coil unit, with which, in the energized state, the armature is mounted for movement along a longitudinal axis of the control device and is movable between a retracted position and an extended position; a tappet, which is mounted for movement along the longitudinal axis and, in the extended position, interacts with a camshaft via a tappet free end in order to adjust the camshaft and is connected at a tappet inner end to the armature; wherein the tappet has a first diameter in a region of the tappet free end and has a second diameter in a region of the tappet inner end, and wherein the first diameter is greater than the second diameter, further comprising an adapter with which the control device can be fastened to a component, wherein the adapter forms a first bearing section for rotatably mounting the tappet in the adapter, wherein the tappet, in the region of the tappet free end, has a bearing surface which interacts with the first bearing section, wherein the tappet, between the tappet free end and the bearing surface, has a fourth diameter which is smaller than the first diameter, further comprising a second bearing section for rotatably mounting the tappet outside the armature, and a spring plate, which embraces the tappet in an annular configuration, has a clearance fit with respect to the tappet, and rests against the tappet in the region of a diameter enlargement of said tappet.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) An exemplary embodiment of the invention application will be described with reference to the enclosed figures below. Wherein:

(2) FIG. 1 is a schematic sectional view of an exemplary embodiment of an electromagnetic control device as proposed herein.

DETAILED DESCRIPTION

(3) FIG. 1 shows a schematic sectional view of an exemplary embodiment of an electromagnetic control device 10 according to the application. It is visible in FIG. 1 that the control device 10 comprises two identical structural units. The following description is of only one of the structural units for clarity reasons, wherein this description applies likewise to the other structural unit.

(4) The control device 10 comprises a housing 12, which has a substantially tube-shaped design in the exemplary embodiment shown. With reference to the view selected in FIG. 1, the housing 12 is closed with a lid 14 at its top end and with a flange 16 at its bottom end. The control device 10 comprises an adapter 18 that can be attached to the flange 16. This adapter 18 can be used to fasten the control device 10 to a cylinder head cover of an internal combustion engine, for example (not shown). The adapter 18 comprises recesses 20 into which seals not shown can be inserted to seal the control device 10 from the cylinder head cover.

(5) The adapter 18 forms a first bearing section 22 for a tappet 24 which can be moved along a longitudinal axis L of the control device 10. The tappet 24 has a free end 26, which projects from the adapter 18. The tappet 24 has a first diameter D1 in the region of the free end 26. In the first bearing section 22, the inner surface of the adapter 18, which interacts with the tappet 24, has a respective surface finish.

(6) In the region of the free end 26, the tappet 24 has a bearing surface 28 which interacts with the bearing section 22. The bearing surface 28 also has a respective surface finish. Between the bearing surface 28 and the free end 26, the tappet 24 has a fourth diameter D4, which is only slightly smaller than the first diameter D1. The tappet 24 forms an offset 30 at the transition from the first diameter D1 to the fourth diameter D4.

(7) The first bearing section 22 is lubricated by means of the engine oil of the internal combustion engine. For safe absorption of the great axial forces which act on the tappet 24 during operation, both the tappet 24 and the adapter 18 are made of a hardened stainless steel.

(8) Furthermore, the tappet 24 has an inner end 32. In the region of the inner end 32, the tappet 24 has a second diameter D2, which is smaller than the first diameter D1 and the fourth diameter D4. Furthermore, the inner end 32 of the tappet 24 is pressed together with an armature 34 and connected to it in a rotationally fixed manner. The rotationally fixed connection can also be implemented in a different manner, for example by welding. To achieve good compression, the armature 34 has a recess into which the tappet 24 engages.

(9) The control device 10 has a second bearing section 36, which in the exemplary embodiment shown is arranged behind the first bearing section 22, starting from the free end 26, and formed by a tube-shaped body 38. In the example shown, the second bearing section 36 is arranged such that only the tappet 24 is mounted in the second bearing section 36. Consequently, the second bearing section 36 is inside the housing 12, while the first bearing section 22 is in the adapter 18 and thus located outside the housing 12. Both the first bearing section 22 and the second bearing section 36 are configured such that the tappet 24 and the armature 34 are mounted for rotation about the longitudinal axis L and for movement along the longitudinal axis L. In the exemplary embodiment shown, the tappet 24 has the second diameter D2 where it interacts with the second bearing section 36.

(10) Furthermore, the control device 10 comprises a spring plate 40, which embraces the tappet 24 in an annular configuration, has a clearance fit with respect to the tappet 24, and rests against the tappet 24 in the region of a diameter enlargement 42 of said tappet. In the extended position, the diameter enlargement 42 of the tappet 24 rests against the adapter 18. The diameter enlargement 42 thus acts as a stop. The diameter enlargement 42 is dimensioned such that it gives the tappet 24 the necessary stability. At the same time, the diameter enlargement 42 is used as a support for the spring plate 40, which is attracted by a permanent magnet 41 and holds the tappet 24 in the extended position, such that the tappet 24 is not inadvertently moved towards the retracted position, for example by viscous oil.

(11) In addition, a spring element 43 is provided, which has a first end 44 and a second end 45. The spring element 43 can provide a biasing force which substantially acts along the longitudinal axis L. At its first end 44, the spring element 43 is supported by the spring plate 40; at its second end 45, it is supported by the tube-shaped body 38. The spring plate 40 thus performs the same axial movements along the longitudinal axis L as the armature 34 and the tappet 24. Due to the clearance fit of the spring plate 36 with respect to the tappet 24, the rotational movements of the tappet 24 are only transmitted to the spring plate 40 when the biasing force with which the spring plate 40 is pressed against the diameter enlargement 42 exceeds a specific value.

(12) The tappet 24 comprises another region 46 between the region of the free end 26 and the region of the inner end 32 in which the tappet has a third diameter D3. In the exemplary embodiment shown, the third diameter D3 is smaller than the first diameter D1 and the fourth diameter D4 but greater than the second diameter D2.

(13) For moving the armature 34, the control device 10 includes a coil unit 48, which encloses the armature 34 in an annular configuration, thereby forming a gap. In addition, a pole core 50 is provided, which is arranged above the armature 34 with respect to the view selected in FIG. 1. Furthermore, the control device 10 comprises another permanent magnet 52, which is fastened to the lid 14 and arranged above the pole core 50.

(14) Since the armature 34 and the tappet 24 are pressed together, they perform the same movements. The tappet 24 and the armature 34 thus do not perform any movements relative to each other, which means that there are no wear points due to relative movements between the armature 34 and the tappet 24.

(15) The control device 10 is operated as follows: The other permanent magnet 52 applies an attractive force acting along the longitudinal axis L to the armature 34, such that, in the retracted state, the armature 34 is attracted by the other permanent magnet 52 and rests against the pole core 50. This compresses the spring element 43, such that the spring element 43 provides a biasing force, which however is smaller than the attractive force of the other permanent magnet 52. As a result, the armature 34 and the tappet 24 adopt a retracted position (see FIG. 1).

(16) If the coil unit 48 is energized, a magnetic field is built which induces a magnetic force that acts in the same direction on the armature 34 as the biasing force provided by the spring element 43 and therefore counteracts the attractive force of the other permanent magnet 52. The sum total of the magnetic force and the biasing force is greater than the attractive force of the other permanent magnet 52, such that the armature 34 and consequently the tappet 24 are moved away from the other permanent magnet 52 along the longitudinal axis L until the spring plate 40 contacts a stop 54, in which way the tappet 24 and the armature 34 have reached an extended position (not shown). In this extended position, the free end 26 of the tappet 24 engages in a groove of a camshaft not shown or a camshaft section not shown. The groove has a helical course relative to the rotational axis of the camshaft, such that engagement of the tappet 24 in the groove in combination with the rotation of the camshaft about its own rotational axis causes a longitudinal adjustment along the rotational axis of the camshaft. To transmit the respective axial forces, the tappet 24 is in contact with one of the side walls of the groove and rolls along it, such that the tappet 24 is rotated at a high rotational speed when engaging in the groove. The rotational movement of the tappet 24 is also transmitted to the armature 34 since the armature 34 and the tappet 24 are pressed together. The stop 54 of the adapter 18 and the depth of the groove are selected such that the free end 26 of the tappet 24 does not contact the bottom surface of the groove in the extended position. To prevent the tappet 24 from being moved back into the retracted position, for example by viscous oil which accumulates under the tappet 24, the tappet 24 is held in its extended position by the permanent magnet 41 in the diameter enlargement 42. But the depth of the groove declines towards the end, such that the free end 26 of the tappet 24 contacts the bottom surface of the groove from a specific angle of rotation, whereby the tappet 24 is once again moved towards the other permanent magnet 52, whereby the holding force of the permanent magnet 41, which gets smaller as the distance of the diameter enlargement 42 from the permanent magnet 41 increases, is overcome. As soon as the tappet 24 is moved from the groove towards the retracted position, energization of the coil unit 48 is interrupted, such that the attractive force applied by the other permanent magnet 52 to the armature 34 is once again greater than the sum total of the biasing force provided by the spring element 43 and the magnetic force which is no longer active due to lack of energization of the coil unit 48. As a result, the tappet 24 and the armature 34 once again adopt the retracted position until the coil unit 48 is energized again.

(17) Since the tappet 24 comprises in the region of its free end 26 the first diameter D1, which is greater than the second diameter D2 in the region of the inner end 32, the tappet 24 has a high bending stiffness compared to known tappets, such that high bending moments can be absorbed without causing bending of the tappet 24 and any resulting jamming in the two bearing sections 22, 36. The other region 46 with the third diameter D3 is designed such that, on the one hand, the weight of the tappet 24 increases just slightly or not at all compared to known tappets, but increased bending stiffness is maintained.

(18) The offset 30 causes dirt which accumulates between the adapter 18 and the tappet 24 in the region of the free end 26 is pushed out of the adapter 18 when the tappet 24 is moved by from the retracted position into the extended position. This prevents blockage of the tappet 24 or damage to the first bearing section 22 due to ingression of dirt particles.

LIST OF REFERENCE SYMBOLS

(19) 10 Control device 12 Housing 14 Lid 16 Flange 18 Adapter 20 Recess 22 First bearing section 24 Tappet 26 Free end 28 Bearing surface 30 Offset 32 Inner end 34 Armature 36 Second bearing section 38 Tube-shaped body 40 Spring plate 41 Permanent magnet 42 Diameter enlargement 43 Spring element 44 First end 45 Second end 46 Other region 48 Coil unit 50 Pole core 52 Other permanent magnet 54 Stop D1 First diameter D2 Second diameter D3 Third diameter D4 Fourth diameter L Longitudinal axis