Electromagnetic actuating mechanism

Abstract

An electromagnetic actuating mechanism comprising an armature unit (10) which can be moved by a certain armature excursion along an axial direction of travel as a result of stationary coil means being energized, plunger means (16) which are associated with the armature unit, are designed such that the end thereof cooperates with an external actuating partner, and can be moved by a certain plunger excursion along the direction of travel from a starting position into an engagement position, and spring means (22) which bias the plunger means in the direction of travel.

Claims

1. An electromagnetic actuating device having an armature unit (10) able to be driven by energizing of stationary coil means by an armature stroke along an axial movement direction, plunger means (16) associated with the armature unit, constructed on the end side for interaction with an external actuation partner and movable by a plunger stroke from a starting position into an engagement position along the movement direction and spring means (22) prestressing the plunger means in the movement direction, wherein the plunger means are movably guided relative to the armature unit and have, on the shell side, a ramp- and/or taper portion (28) between a plunger portion of larger diameter (26), on the armature side, and a plunger portion (30) with a smaller diameter, a pressure body (32), contained under prestressing in a housing section (18) guiding the plunger means, wherein the pressure body (32) interacts on the shell side with the ramp- or respectively taper portion and the ramp- or respectively taper portion is provided on the plunger means so that the pressure body, with a non-energized coil unit and/or with a non-driven armature unit through application of force on the shell side onto the ramp- or respectively taper portion returns the plunger means against the prestressing of the spring means in the direction of the starting position, wherein the armature stroke is smaller than the plunger stroke.

2. The device according to claim 1, wherein the pressure body is constructed as a ball or a body having a spherical segment.

3. The device according to claim 2, wherein the pressure body is provided in the form of a plurality of pressure bodies arranged distributed around a circumference of the plunger means.

4. The device according to claim 1 wherein the ramp- or respectively taper portion (28) has an extent along the axial movement direction which is greater than a diameter or an axial extent of the pressure body and/or is between 50% and 150% of the armature stroke.

5. The device according to claim 4, wherein the ramp- or respectively taper portion (28) has an extent along the axial movement direction which is greater than a diameter or an axial extent of the pressure body and/or is between 80% and 120% of the armature stroke.

6. The device according to claim 1, wherein the ramp- or respectively taper portion (28) is inclined in longitudinal section by an angle (a) between 20° and 60° to the longitudinal axis of the movement direction.

7. The device according to claim 6, wherein the angle (a) is between 30° and 40°.

8. The device according to claim 1, wherein the plunger stroke is at least 1.5 times the armature stroke.

9. The device according to claim 8, wherein the plunger stroke is at least 2.5 times the armature stroke.

10. The device according to claim 1, wherein the plunger means (16), realized radially symmetrically about the movement longitudinal axis of the movement direction have an internal widening to accommodate the spring means, constructed as a spiral spring, and/or have an inner shoulder offering a stop (20) for the spring means.

11. The device according to claim 10, wherein the spring means, constructed as compression- and/or spiral spring (22), rest at one end against the plunger means (16), at the other end against a portion (24) of the housing (18) guiding the plunger means.

12. The device according to claim 10, wherein the inner shoulder is an annular shoulder.

13. The device according to claim 1, wherein the armature unit is constructed in a monostable manner so that after a termination of the energizing, the armature unit reverts into an armature starting position.

14. The device according to claim 13, wherein the armature unit is dimensioned and arranged so that in the armature starting position no mechanical contact with the plunger means exists.

15. The device according to claim 1, wherein the plunger means are constructed for interaction with an actuation groove (36) as actuation partner so that a change in position and/or depth of the actuation groove can bring about a moving of the plunger means in a restoring direction opposed to the movement direction.

16. The device according to claim 1, wherein the armature unit has permanent magnet means, which are constructed for interacting with means for detecting the position, movement and/or restoration of the armature unit.

17. A camshaft adjustment system having the electromagnetic actuating device according to claim 1, and an adjustment groove as actuation partner for engaging by the camshaft adjustment unit of an internal combustion engine, offering plunger means, wherein the actuation groove and the plunger means are constructed and aligned axially to one another so that the actuation groove can carry out a first restoring stroke on the plunger means contrary to the movement direction, and the first restoring stroke can move the pressure body against the ramp- or respectively taper portion to bring about an axially aligned second restoring stroke through the application force on the shell side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features and details of the present invention will emerge from the following description of preferred example embodiments and with the aid of the single figure; this shows in:

(2) FIG. 1 a diagrammatic longitudinal section illustration of the electromagnetic actuating device according to a first preferred embodiment of the invention, symbolically divided along the vertical symmetry- and movement axis into a withdrawn starting position (on the right) and an engagement state (on the left) relative to a camshaft switching link as engagement partner.

DETAILED DESCRIPTION

(3) In the longitudinal groove illustration of FIG. 1, reference number 10 shows symbolically an armature unit with an elongated armature plunger 12 and a widened armature body 14 relative thereto. By the energizable coil means (not shown in the FIGURE) the armature unit 10 is movable in another otherwise known manner relative to a stationary core unit (not shown) between an armature starting position (FIG. 1, right) and an armature advance position (FIG. 1, left half). In a practical realization, a typical armature stroke lies in the range between 1 and 1.5 mm with an effective stroke of the plunger means of approximately 4 mm.

(4) As FIG. 1 further illustrates diagrammatically, the armature plunger portion 12 engages internally onto a plunger unit (plunger means) 16, which is guided in a surrounding plunger housing 18. As the longitudinal section illustration of FIG. 1 shows, the plunger unit 16 is open on the base side, in the direction of the armature unit 10, for accommodating the armature plunger portion 12; the latter is dimensioned so that in the armature starting position (FIG. 1, right half) it maintains a—small—distance from the plunger and only with an advance then entrains the plunger 16 along the movement direction (downwards in the FIGURE plane of FIG. 1).

(5) In addition, a spiral spring 22 is shown, engaging onto a base or respectively onto an annular shoulder 20 of the plunger unit 16, which spiral spring is supported at the other end by an annular base 24 of the plunger housing 18. In the right-hand half of FIG. 1, in this respect corresponding to the starting position of the plunger means 16, the spiral spring 22 is accordingly compressed and exerts a maximum prestressing on the plunger unit 16 in a downwardly-directed movement direction.

(6) The plunger unit 16 has, in the direction of the armature unit 10, a plunger portion 26 of greater external diameter; over a taper portion 28 this (larger) external diameter narrows in a front plunger portion 30, on the engagement side, of reduced external diameter. As the longitudinal section view shows, the taper portion 28 extends over an axial length of approximately 1.2 mm with an angle in relation to the vertical movement axis of approximately 25°. In this respect, the axial extent (axial length) of the taper portion 28 corresponds to the armature stroke, plus the distance (with play) between an engagement end 34 of the plunger unit and the actuation partner in the non-engagement state.

(7) As FIG. 1 additionally shows, pressure bodies 32 in the form of balls arranged distributed around the circumference of the plunger unit 16 engage onto the surface shell of the plunger unit; these pressure bodies 32 in the form of balls are prestressed by their own compression springs 33 extending horizontally (and therefore radially to the movement longitudinal axis).

(8) On the engagement side, i.e. opposed to the armature unit 10, the plunger unit 16 forms the engagement portion (engagement end) 34, which is dimensioned to interact with an actuation groove 36 of a switching link, shown by way of example as an actuation partner 38, of a camshaft adjustment system; the double arrow 40 illustrates the groove depth, in the example shown, of approximately 3.7 mm, which is covered by the plunger stroke (here approximately 4 mm).

(9) The operation of the device shown in FIG. 1 is as follows:

(10) From the starting position of the armature unit (right half of FIG. 1), by energizing of the coil means (not shown), firstly a movement takes place of the armature unit (consisting of the armature body 14 and the armature plunger 12 sitting directly and securely thereon, alternatively sitting thereon in a (permanent-)magnetically adhering manner) along the movement direction, therefore downwards in FIG. 1; the armature stroke lies in the range between approximately 1 and 1.5 mm. On reaching the abutment 20 of the plunger unit 16, the latter is entrained along the movement direction; at the same time the taper portion 28 moves in downward direction along the horizontally stationary spherical pressure bodies 32, until these lie on the (upper) cylindrical shell portion 26 of the plunger unit. Whilst the relaxing compression spring 22 has already assisted the armature movement and in this respect has exerted an additional, downward-directed actuating force onto the plunger unit 16, the compression spring 22 completely undertakes the further, downward-directed advance of the plunger unit 16, as soon as the armature unit reaches its stop state against the housing 18 (FIG. 1, left-hand region for the armature stop); whilst the spring 22 guides the plunger unit further downward, the armature plunger portion 12 separates from the plunger unit 10.

(11) The left-hand region of FIG. 1 shows the completely pushed-out state of the armature plunger 16 from the housing 18. The plunger unit 16 has carried out a total stroke of approximately 4 mm and engages in this state into the groove 36 of the actuation partner 38. On rotation of the assembly, the camshaft adjustment takes place in an otherwise known manner.

(12) The actuation groove 36 also brings about the restoring of the plunger 16 along a first restoring stroke portion; in practice, a reducing groove depth (on rotation of the actuation partner 38) leads to the plunger unit 16 being pushed in the restoring direction (i.e. upwards in the FIGURE plane of FIG. 1). The device which is shown is dimensioned here so that this restoring takes place axially along the first restoring stroke until the pressure bodies 32 in the form of balls, engaging onto the cylindrical shell surface 26, reach the start of the taper portion 28 (acting as a ramp). At this moment the radial application of force of the balls as pressure bodies 32 leads to the restoring movement being continued along the taper surface in the direction toward the starting position, wherein the taper in this respect determines a second restoring stroke, following the first restoring stroke of the groove, until into the starting position, shown on the right in FIG. 1. As the armature unit 10 is embodied so as to be monostable in the previously described manner, the plunger unit 16 does not have to additionally also restore the armature unit 10 in this restoring process (for instance by entrainment of the portion 12), rather immediately after the end of energizing already on guiding out of the plunger 16 a reverting of the armature unit 10 into its monostable end position (FIG. 1, right) took place. Alternatively, a bistable configuration, for instance by means of an armature body 14 realized permanent-magnetically, can also be expedient, in particular also with regard to a (magnetic field-detected) position-, movement- and/or restoration detection able to be realized thereby.