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 the 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; a tappet which interacts with the armature and is mounted for movement along the longitudinal axis, having a free end, via which the tappet interacts with the camshaft in the extended position in order to adjust the camshaft; and an adapter, via which the control device can be fastened to a component, in particular to cylinder head cover, wherein the armature and the tappet are connected to each other for conjoint rotation, and the control device has a first bearing section inside the adapter for rotatable mounting of the tappet and a second bearing section outside of the adapter for rotatable mounting of the tappet and/or the armature.

Claims

1. An electromagnetic control device, comprising: an armature; an energizable coil unit, with which the armature is mounted to be movable along a longitudinal axis of the control device in an energized condition and is movable between a retracted position and an extended position relative to a pole core; a tappet which interacts with the armature and is mounted for movement along the longitudinal axis and has a free end by which the tappet interacts with a camshaft in the extended position for adjusting the camshaft; an adapter to a cylinder head cover; a first bearing section within the adapter for rotational bearing of the tappet; a second bearing section outside of the adapter for rotatable mounting of the tappet and/or the armature; and wherein the armature and the tappet are connected to one another for conjoint rotation.

2. The control device according to claim 1, wherein the second bearing section is made of a nonmagnetic or nonmagnetizable material.

3. The control device according to claim 1, wherein the second bearing section comprises a friction bearing or is formed by the friction bearing.

4. The control device according to claim 3, wherein the friction bearing is made of plastic or a nonmagnetic or a nonmagnetizable stainless steel.

5. The control device according to claim 3, wherein the friction bearing is arranged in a tubular body.

6. The control device according to claim 1, further comprising: a spring element having a first end and a second end, the spring element being supported on the first end by a spring plate on the tappet or on the armature and being supported at the second end on the second bearing section.

7. The control device according to claim 5, wherein the adapter has a stop against which the spring plate is stopped in the extended position.

8. The control device according to claim 1, further comprising: a permanent magnet, with which the armature in an unenergized condition of the coil unit is held in the retracted position.

9. A device, comprising: a housing having a longitudinal axis; an energizable coil unit located in the housing; a tappet that extends along the longitudinal axis and having a free end for interaction with a camshaft; an armature fixed to the tappet and extending along the longitudinal axis; an adapter extending from the housing and having a first bearing section for rotational bearing of the tappet, wherein the first bearing section is located in the adapter and outside of the housing; a second bearing section located in the housing for rotational bearing of the tappet, the armature, or both the tappet and armature; wherein the tappet is rotatably mounted in the first bearing section, and the armature, the tappet, or both the armature and tappet, are rotatably mounted in the second bearing section; and wherein the tappet and armature conjointly rotate and move longitudinally along the longitudinal axis between a retracted position and an extended position without rotation of the tappet and armature relative to each other.

10. The device according to claim 9, further comprising: a spring having a spring first end and a spring second end; a spring plate; wherein the spring first end is supported by the spring plate on the tappet or on the armature and the spring second end is supported on the second bearing section.

11. The device according to claim 10, wherein the adapter has a stop against which the spring plate is stopped when the tappet and armature are in the extended position.

Description

[0019] Examples of embodiments of the invention are described in greater detail below with reference to the accompanying drawings, in which:

[0020] FIG. 1 shows a basic sectional diagram through one embodiment of a proposed electromagnetic control device.

[0021] FIG. 1 shows an embodiment of an inventive electromagnetic control device 10 on the basis of a basic sectional diagram. FIG. 1 shows that the control device 10 has two components of identical design. For reasons of clarity, essentially only one of the components is described below, but the description also applies to the other component.

[0022] The control device 10 has a housing 12 which is designed essentially in the form of a pipe in the embodiment illustrated here. With respect to the diagram shown in FIG. 1, the housing 12 is closed with a flange 16 at the lower end and with a cover 14 at the upper end. The control device 10 has an adapter 18 attached to the flange 16. With this adapter 18, the control device 10 can be attached to a cylinder head cover of an internal combustion engine, for example (not shown). The adapter 18 has recesses 20 into which gaskets (not shown) can be inserted to seal the control device 10 with respect to the cylinder head cover.

[0023] The adapter 18 forms a first bearing section 22 for a tappet 24 that is displaceable along a longitudinal axis L of the control device 10. The first bearing section 22 may be provided, for example, by the fact that the outer surface of the tappet 24 is provided with a corresponding surface quality just like the inner surface of the adapter 18, which comes in contact with the outer surface of the tappet 24. The first bearing section 22 is lubricated by the motor oil of the internal combustion engine. To be able to reliably absorb the high axial forces acting on the tappet 24 during operation, the adapter 18 is made of a hardened stainless steel.

[0024] The tappet 24 in the embodiment illustrated here is produced with an armature 26 by compression molding and is therefore connected to it for conjoint rotation. The conjoint rotation connection may also be implemented by some other method, for example, by welding. To achieve good compression molding, the armature 26 has a recess, in which the tappet 24 engages over a lengthy section. The tappet 24 has a free end 28 which protrudes beyond the adapter 18.

[0025] In the embodiment shown here, the control device 10 has a second bearing section 30, which is arranged behind the first bearing section 22, as seen from the free end 28 and is designed as a friction bearing 32. The friction bearing 32, which is manufactured from a plastic, for example, or a nonmagnetic stainless steel, is arranged in a tubular body 34 and is connected to the tubular body 34 by means of a shrink fit, for example. In the example shown here, the friction bearing 32 is arranged so that only the armature 26 is supported with the friction bearing 32. Consequently, the second bearing section 30 is situated inside the housing 12. Both the first bearing section 22 and the second bearing section 30 are designed so that the tappet 24 and the armature 26 are mounted to rotate about the longitudinal axis L as well as to be displaceable along the longitudinal axis L. The friction bearing 32 protrudes radially inward somewhat beyond the tubular body 34 so that a narrow gap is formed between the tubular body 34 and the armature 26. The tubular body 34 and the armature 26 are therefore not in contact with one another.

[0026] Furthermore, the control device 10 has a spring plate 36 which extends around the tappet 24 in the form of a ring and has a loose fit with respect to the tappet 24 and is contact with the tappet 24 in the area of an enlarged diameter 38 thereof. In addition the spring plate 36 is secured axially by means of the armature 26. Consequently, the spring plate 36 executes the same axial movements along the longitudinal axis L as the armature 26 and the tappet 24. As shown in FIG. 1, the spring plate 36 is enclosed radially by the tubular body 34. In the axial movements of the spring plate 36, the spring plate 36 is guided by the tubular body 34.

[0027] In addition a spring element 40 having a first end 42 and a second end 44 is provided. The spring element 40 may supply a prestressing force that acts essentially along the longitudinal axis L. The spring element 40 is supported with the first end 42 on the spring plate 36 and with its second end 44 on the friction bearing 32. Because of the loose fit of the spring plate 36 with respect to the tappet 34, rotational movements of the tappet 24 are then transferred to the spring plate 36 only when the prestressing force with which the spring plate 36 is pressed against the area of enlarged diameter 38 exceeds a certain level.

[0028] To move the armature 26, the control device 10 includes a coil unit 46 enclosing the armature 26 and forming an annular gap. In addition, a pole core 48 which is provided is arranged above the armature 26 based on the diagram shown in FIG. 1. Furthermore, the control device 10 has a permanent magnet 50 which is attached to the cover 14 and is arranged above the pole core 48.

[0029] Due to the fact that the armature 26 and the tappet 24 are produced together by compression molding, they always execute the same movements. Consequently, the tappet 24 and the armature 26 do not execute any movements relative to one another so that there are no wear spots caused by the relative movements between the armature 26 and the tappet 24. The left tappet 24 and the left armature 26 are in a retracted position, whereas the right tappet 24 and the right armature 26 are in an extended position.

[0030] The control device 10 is operated in the following manner: the permanent magnet 50 exerts an attractive force on the armature 26 acting along the longitudinal axis L, so that the armature 26 is pulled by the permanent magnet 50 in the retracted condition and is in contact with the pole core 48. The spring element 40 is compressed in this way, so that the spring element 40 supplies a prestressing force, which, however, is lower than the attractive force of the permanent magnet 50. Consequently, the armature 26 and the tappet 24 assume the retracted position.

[0031] If the coil unit 46 is now energized, a magnetic field is built up, inducing a magnetic force on the armature 26, causing an action in the same direction as the prestressing force supplied by the spring element 40, and consequently, against the attractive force of the permanent magnet 50. The sum of the magnetic force and the prestressing force is greater than the attractive force of the permanent magnet 50, so that the armature 26, and consequently, the tappet 24 are moved away from the permanent magnet 50 along the longitudinal axis L until the spring plate 36 strikes against a stop 52 on the adapter 18, so that the tappet 24 and the armature 26 have reached the same extended position. In this extended position, the tappet 24 engages at its free end 28 in a groove in a camshaft (not shown) or a camshaft section (also not shown). The groove has a helical shape, based on the axis of rotation of the camshaft, so that engagement of the tappet 24 in the groove causes a longitudinal adjustment along the axis of rotation of the camshaft about its own axis of rotation in combination with the rotation of the camshaft. To transfer the corresponding axial forces, the tappet 24 is in contact with one of the side walls of the groove on which it rolls, so that the tappet 24 is rotated at a very high rotational speed on engagement in the groove. Because of the compression molding of the armature 26 with the tappet 24, the rotational movement of the tappet 24 is also transferred to the armature 26. The stop 52 of the adapter 18 and the depth of the groove are selected so that the tappet 24 in the extended position does not at its free end 28 contact the bottom surface of the groove. However, the depth of the groove decreases toward the end, so that beyond a certain angle of rotation of the camshaft, the free end 28 of the tappet 24 comes in contact with the bottom surface of the groove, so that the tappet 24 is again displaced in the direction of the permanent magnet 50. Then at the latest, energization of the coil unit 46 is interrupted, so that the attractive force exerted by the permanent magnet 50 on the armature 26 is again greater than the sum of the prestressing force supplied by the spring element 40 and the magnetic force, which is no longer in effect due to the lack of energization of the coil unit 46. Consequently, the tappet 24 and the armature 26 again assume the retracted position until the coil unit 46 is again energized.

LIST OF REFERENCE NUMERALS

[0032] 10 Control device [0033] 12 Housing [0034] 14 Cover [0035] 16 Flange [0036] 18 Adapter [0037] 20 Recesses [0038] 22 First bearing section [0039] 24 Tappet [0040] 26 Armature [0041] 28 Free end [0042] 30 Second bearing section [0043] 32 Friction bearing [0044] 34 Tubular body [0045] 36 Spring plate [0046] 38 Area of enlarged diameter [0047] 40 Spring element [0048] 42 First end [0049] 44 Second end [0050] 46 Coil unit [0051] 48 Pole core [0052] 50 Permanent magnet [0053] 52 Stop [0054] Longitudinal axis