DE102009053121A1 - Electromagnetic actuating device for controlling stroke-variable valve drive of internal-combustion engine, has locking pins subjected with force by magnetic circuit in electromagnet in extending direction for blocking latch - Google Patents

Abstract

The device (1) has actuator pins (8, 9) retracted into a housing (10) in rest position and extended out from the housing in working position. Locking pins (12, 13) act together with the actuator pins by a latch. A magnetic circuit is formed in an electromagnet (21) that stays in current-supplied condition, and moves the locking pins in retracting direction for releasing the latch. The locking pins are subjected with force by another magnetic circuit in the electromagnet in the extending direction for blocking the latch, where the electromagnet stays in current-unsupplied condition.

Description

Field of the invention

The invention relates to an electromagnetic actuator having a housing, an electromagnet, an actuator pin which is movably mounted in the housing between a retracted in the housing rest position and an extended from the housing working position and is subjected to force by a spring means in the extension, a detent and a with the Actuator pin cooperating by means of detent locking pin, which holds the actuator pin with locked detent in the rest position and is displaceable relative to this in the direction of travel of the actuator. In this case, an actuator pin facing away from the head portion of the locking pin is provided with a two-pole magnetized permanent magnet in the direction of travel, and a trained with energized electromagnet first magnetic circuit displaces the locking pin in the retraction direction to release the detent

Background of the invention

Such an actuator is not previously published DE 10 2009 010 949 A1 known and is particularly suitable for adjusting hubvariabler valve drives of internal combustion engines whose basic operation, for example, from the DE 10 2004 021 376 A1 evident. The stroke variability of this valve train is based on a cam piece with two cams arranged directly adjacent thereto, the different opening characteristics of which are selectively transferred to a gas exchange valve by means of a conventionally rigid cam follower. For operating point-dependent adjustment of these opening courses, the cam piece is non-rotatably, but arranged longitudinally displaceable on a support shaft and has two spiral and oppositely extending sliding grooves, in which the end portions of the actuator pins of two actuators (with only one Aktuatorstift) are alternately coupled. While the axial course of the sliding groove engaged with the associated actuator pin causes the cam piece to move from one cam position to the other camshaft in self-control and camshaft angle, the radial course of each slide groove is designed to increase toward the end of the shifting operation flatten and the currently engaged actuator pin from its working position shifted back to the rest position.

In the case of a valve train with three adjacent cams and - depending on the structural design of the sliding grooves - two or three arranged at a small distance actuator pins (see DE 196 11 641 C1 respectively. DE 10 2007 010 149 A1 ) appears an adjusting device expedient in which the actuator pins are integrated in a common housing (multiple actuator).

Electromagnetic actuators, in which the actuator pins or are held by means of the aforementioned locking pin detent in the retracted rest position, go not only from the erstzitierten DE 10 2009 010 949 A1 but also from the DE 10 2008 020 892 A1 and the DE 10 2008 020 893 A1 out. In all cases, a spring is provided which forces the locking pin in the extension direction to lock the detent.

Object of the invention

The present invention has for its object to simplify an adjusting device of the type mentioned manufacturing and assembly technology.

Summary of the invention

The solution to this problem arises from the features of claim 1, while advantageous developments and refinements the dependent claims are removed. Accordingly, the object is achieved in that a forming in the current-energized electromagnet second magnetic circuit force the locking pin in the extension direction to lock the detent. In other words, the well-known in the art spring and cooperating spring pads on locking pin and housing can be omitted and replaced by magnetic force, which acts on the locking pin in the de-energized state of the solenoid in the extension direction.

In a further development of the invention, it is provided that the head portion of the locking pin is provided on the side facing away from the electromagnet of the permanent magnet with a magnet armature. In this case, in the rest position of the actuator each of the armature so to the housing and the permanent magnet so spaced from the electromagnet, that when energized electromagnet acting in the extension magnetic attraction between armature and housing is greater than acting in the retraction magnetic attraction between permanent magnet and electromagnet , In this embodiment, it depends so much on what distances, ie magnetically active air gaps, the permanent magnet to the pole face of the electromagnet on the one hand and the armature to the housing on the other occupy the other when the detent is locked. These distances are to be matched to one another so that the locking pin is sufficient with both energized and energized electromagnet large magnetic force in the extension direction or in the retraction is acted upon.

It has been found to be advantageous if the polarity of the permanent magnet is aligned so that face with energized electromagnet, the permanent magnet and the electromagnet with the same poles and acting in the retraction magnetic repulsion force between armature and housing greater than acting in the extension direction magnetic repulsion force between permanent magnet and electromagnet is.

The magnet armature should preferably have the shape of a truncated cone tapering in the extension direction, the outer shell of which, in the rest position of the actuator pin, extends around an air gap at a distance from a frustoconical inner shell section of the housing. In this case, the magnetic force component acting in the direction of travel can be adjusted both via the radial distance between magnet armature and housing and via the cone angle of the magnet armature. In this alternative embodiments, but also different shapes of magnet armature and the magnetically cooperating housing portion may be provided to produce a desired magnetic force characteristic. For example, the armature can be cylindrical and cooperate with an axial end face in the housing.

In the case of the multi-actuator mentioned above, two actuator pins and two locking pins are provided with polarized opposite to each other in the direction of travel permanent magnets. The electromagnet is assigned to the permanent magnet together and formed to form the first magnetic circuit with reversible effective direction such that the first magnetic circuit displaces the locking pin in the direction of insertion in one direction of action and the further locking pin in the extension direction kraftbeaufschlagt and that the first magnetic circuit in the other effective direction the force of the locking pin in the extension direction and displaced the further locking pin in the retraction direction.

The opposite polar alignment of the permanent magnets causes the same magnetic circuit to attract or repel the permanent magnets when the electromagnet is energized. In this case, the locking pin provided with the attracted permanent magnet is subjected to a force in the extension direction, since the attraction force between the armature and the housing is even greater than the force of attraction between the permanent magnet and the electromagnet. On the other hand, the locking pin provided with the repelled permanent magnet is displaced in the retraction direction, since the repulsive force between the armature and the housing is even greater than the repulsive force between the permanent magnet and the electromagnet. Consequently, only one actuator pin, which cooperates with the retracting locking pin, then extend in detent release in its working position. The reversing effective direction of the magnetic circuit can be generated by the fact that the electromagnet is energized with a correspondingly reversed polarity.

Alternatively, however, an adjusting device with rectified poled permanent magnets and only one direction of action of the first magnetic circuit (with energized electromagnet) may be provided. In this case, both actuator pins would be operated simultaneously, but only one actuator pin would face a sliding groove, while the other actuator pin would be obstructed by the cam piece being extended. Such operation of the actuator is basically from DE 10 2007 010 156 A1 known. The quoted in the above DE 10 2009 010 949 A1 disclosed adjusting device could be structurally simplified in terms of this operation, that the pressure springs proposed there for eliminating the force of the locking pins in the extension and omitted according to the present invention are replaced by magnetic forces.

• • eine im Aktuatorstift verlaufende Längsbohrung zur Aufnahme des Sperrstifts und eine oder mehrere die Längsbohrung schneidende Querbohrungen,
• • eine am Sperrstift ausgebildete erste Stützfläche und eine im Gehäuse ausgebildete zweite Stützfläche, wobei zumindest eine der Stützflächen gegenüber der Verfahrrichtung geneigt verläuft,
• • und Rastkörper, die in den Querbohrungen beweglich angeordnet und in der Ruheposition zwischen den Stützflächen eingespannt sind.

In structurally expedient embodiment, the detent should have the following features:

• A longitudinal bore extending in the actuator pin for receiving the locking pin and one or more transverse bores cutting the longitudinal bore,
• A first support surface formed on the locking pin and a second support surface formed in the housing, wherein at least one of the support surfaces is inclined with respect to the direction of travel,
• • and locking body, which are arranged movably in the transverse bores and clamped in the rest position between the support surfaces.

In such, based on form or frictional engagement detent only small effective areas are required to the. Actuator pin against the force of the spring means to keep safe in its rest position. In contrast to the holding forces which can be generated in this way, the forces required to release the detent are many times lower, since only the frictional forces acting between the detent bodies and the supporting surfaces have to be overcome.

The one or more locking bodies are preferably formed as balls, as they are removable as an extremely cost-effective mass product of a rolling element. In this case, three balls and three evenly distributed over the circumference of the actuator pin transverse bores may be provided. These Arrangement is compared to only one catch body insofar advantageous as either greater holding forces can be generated with identical dimensioning of the locking body or smaller dimensioning of the locking body - according to a further reduced space requirements of the detent - which may already sufficient holding force only a detent body can be generated. On the other hand, the arrangement of circumferentially distributed by 120 ° balls leads to a mechanically favorable, centered support of the locking pin in the longitudinal bore of the actuator pin. Nevertheless, of course, arrangements with only one, two, four or more balls are possible.

In addition, the balls may be self-locking clamped between the support surfaces, wherein the support surfaces have a constant or a decreasing in the retraction distance from each other. For example, the second support surface may be parallel to the direction of travel of the actuator pin and be part of a production-wise continuous cylindrical guide for the Aktuatorstift. It may also be expedient that the first support surface on the locking pin tapers radially in the extension direction and that the support surfaces extend parallel to one another. In the case of rotationally symmetrical support surfaces then the support surfaces are formed kreisflgelstumpfförmig. This embodiment allows a particularly low-wear sliding or rolling contact between the balls and the support surfaces when the actuator pin leaves the rest position and reached again.

In the structural design of the support surfaces, of course, both the forces of the spring means and the friction conditions on the ball support surface contacts must be considered in order not to leave the necessary for proper function of the detent region of self-locking at these contacts.

Short description of the drawing

Further features of the invention will become apparent from the following description and from the figures, in which an embodiment of an adjusting device according to the invention is shown. Unless otherwise stated, the same or functionally identical features or components are provided with the same reference numbers. Show it:

1 an electromagnetic actuator with two actuator pins in longitudinal section,

2 the detail X out 1 .

3 the detail Y out 1 .

4 a known embodiment of a cooperating with an actuator stroke variable valve train of an internal combustion engine,

5 the detail Z out 2 with no-current electromagnet,

6 one 5 corresponding force-displacement diagram,

7 the detail Z out 2 with energized electromagnet and

8th one 7 corresponding force-displacement diagram.

Detailed description of the drawing

1 discloses an embodiment of an adjusting device according to the invention 1 , which is used to control a basically known variable-stroke valve drive of an internal combustion engine. The basic operating principle of such a valve train is in 4 represented and summarized to the effect that instead of a conventionally rigid camshaft, a carrier shaft 2 with a non-rotatably and longitudinally displaceable cam piece 3 is provided. The cam piece 3 has two groups of axially adjacent cams 4 and 5 with different opening gradients, the operating point-dependent actuation of gas exchange valves 6 serve. The for selective activation of the respective cam 4 or 5 required displacement of the cam piece 3 on the carrier shaft 2 via helical sliding grooves 7 on the cam piece 3 , Which differ according to the direction of displacement in their orientation and in, depending on the instantaneous position of the cam piece 3 , one actuator pin each 8th or 9 can be coupled.

An adjusting device according to the present invention 1 can, as in 4 illustrated, as a single actuator with only one actuator pin or as a multiple actuator, which in the embodiment according to 1 two actuator pins 8th and 9 having. The actuator pins spaced apart by a cam width 8th . 9 are suitable, for example, for controlling a three-stage variable stroke valve train according to the cited above DE 196 11 641 C1 , At the actuator 1 it is a unit which can be mounted in the cylinder head of the internal combustion engine and has a housing 10 and the two arranged therein, hollow cylindrical actuator pins 8th . 9 , The trained as equal parts actuator pins 8th . 9 are in longitudinal guides of the housing 10 stored and can independently between one in the housing 10 retracted rest position (as shown) and one out of the housing 10 extended working position back and forth. As explained above, the actuator pins are 8th . 9 in the working position (not shown) with a corresponding sliding groove of a cam piece to move the cam piece axially on a support shaft.

The spring means - here helical compression springs 11 - In the extension direction kraftbeaufschlagten actuator pins 8th . 9 be held by detents in the retracted rest position. A release of the detents is done by controllable locking pins 12 and 13 , which are also designed as identical parts and relative to the Aktuatorstiften 8th . 9 are displaced in the direction of travel.

As in 3 clarified, the mutually identical detents are each by a in Aktuatorstift 8th . 9 extending longitudinal bore 14 and these cutting cross holes 15 , one at the locking pin 12 . 13 trained first support surface 16 and one in the housing 10 trained second support surface 17 and three locking bodies in the form of balls 18 educated. The in the evenly on the circumference of the Aktuatorstifts 8th . 9 distributed transverse bores 15 movably arranged balls 18 are in the rest position of the actuator pin 8th . 9 between the support surfaces 16 . 17 clamped. For this purpose, the tapered in the longitudinal bore 14 extending end portion of the locking pin 12 . 13 tapered in the extension direction, leaving the first support surface 16 forms the outer circumferential surface of a circular truncated cone. The second support surface 17 in the case 10 runs at a constant distance to and thus forms the inner circumferential surface of a circular truncated cone. The angle of inclination of the supporting surfaces 16 . 17 opposite to the direction of travel, taking into account the on the locking pin 12 . 13 and the actuator pin 8th . 9 acting forces and the friction conditions on the ball-support surface contacts chosen so that the balls 18 self-locking between the support surfaces 16 . 17 are clamped and so the actuator pin 8th . 9 secure in the rest position. The inclination angle is presently about 5 °.

The locking pins 12 . 13 are at theirs the actuator pins 8th . 9 remote head portions with permanent magnets attached thereto 19 respectively. 20 provided (see 2 ). These are magnetized bipolar axially, in the direction of travel with respect to their designated N and S north and south poles aligned opposite to each other and together a single electromagnet 21 assigned. Furthermore, the head portions are at the electromagnet 21 opposite sides each with a magnet armature 22 provided in the form of a tapered in the extension direction truncated cone, the outer shell in the rest position of the Aktuatorstifts 8th . 9 around an air gap r (see 5 ) spaced apart to a frusto-conical inner shell portion of the housing 10 runs.

The electromagnet 21 comprises as essential components a magnetic coil 23 , a stationary core area 24 and a connector 25 as DC connection for the solenoid coil 23 , The coaxial in the solenoid 23 extending core area 24 points on the part of the permanent magnets 19 . 20 a shoulder on which has a flat contact surface 26 for the locking pins 12 . 13 forms. An adhesive system of the permanent magnets 19 . 20 at the contact surface 26 This avoids the locking pins 12 . 13 opposite the permanent magnets 19 . 20 to survive the measure s1.

The 5 and 6 illustrate the magnetic force relationships on the locking pins 12 . 13 with de-energized magnetic coil 23 and here as an example for the locking pin 13 , In the rest position of the actuator pin 9 are the permanent magnet 20 and the core area 24 spaced apart by the dimension s2, while the armature 22 and the case 10 Radially around the air gap r and axially spaced by the dimension s3 from each other. A self-energized electromagnet 21 forming second magnetic circuit - with energized electromagnet 21 A first magnetic circuit, which will be explained later, forms - flows through the air gap r, wherein the cone angle α of the magnet armature 22 generates a force acting in the extension direction magnetic force component Fa2 of the normal magnetic force Fmag. From the core area 24 generates the permanent magnet 20 a magnetic force Fa1 acting in the retraction direction.

6 shows the course of the magnetic forces Fa1 and Fa2 as a function of the Sperrstiftweges, ie the distance s between the permanent magnet 20 and core area 24 , Due to the supernatant 51 is the force acting in the extension direction of the magnetic force Fa2 always greater than the force acting in the retraction magnetic force Fa1, so that the locking pin 13 It is always acted upon by a total force Fr acting in the extension direction, which holds the detent locked.

The 7 and 8th illustrate with energized magnetic coil 23 the magnetic force conditions on the locking pin 13 , starting with its displacement in the retraction direction at the time of the path coordinate s = s2. The at the magnetic coil 23 applied voltage is polarized (+/-), that the first magnetic circuit at the core area 24 a north pole N and the inner shell portion of the housing 10 a south pole S is formed. The polarity of the permanent magnet 20 is oriented so that the north pole N and the south pole S face each magnetically repulsive. As in 8th shown, are due to this repelling effect, the two magnetic forces Fa1 and Fa2 negative, ie they act against the in 7 Plotted arrow direction. And since the magnetic force Fa2 is always larger in magnitude than the magnetic force Fa1, the lock pin becomes 13 with a force acting in the retraction total magnet force Fres applied to the locking pin 13 to the plant at the core area 24 , ie displaced to the path coordinate s = s1, while the detent is released and the actuator pin 9 extending. The energization of the magnetic coil 23 can be turned off about this time, so the locking pin 13 to return to the illustrated starting position (s = s2) and the actuator pin shifted back from the outgoing sliding groove of the cam piece to its rest position 9 can engage.

The at the polarized energization of the solenoid 23 forming effective direction of the first magnetic circuit generated at the further locking pin 12 a total magnetic force Fres, which is the further locking pin 12 acted upon in the extension direction and keeps the detent locked. Reason is the opposite polarity of the permanent magnets 19 . 20 leading to the following (not shown) magnetic force conditions at the further locking pin 12 leads. The magnetic forces Fa1 and Fa2 are one 8th identical course, with only their sign positive according to the in 7 is indicated arrow direction. Consequently, in an associated force-displacement diagram, only the ordinate F would be in the opposite direction, ie in 8th have downward, so that the force acting in the extension direction of the magnetic force Fa2 is greater than the force acting in the retraction magnetic force Fa1.

An extension of the other actuator pin 8th from its rest position is in an analogous manner by reverse polarity (- / +) of the magnetic coil 23 applied voltage corresponding to the reverse direction of action of the first magnetic circuit causes.

LIST OF REFERENCE NUMBERS

1

locking device

2

carrier wave

3

cam piece

4

cam

5

cam

6

Gas exchange valve

7

shift groove

8th

actuator pin

9

actuator pin

10

casing

11

Spring means / helical compression spring

12

locking pin

13

locking pin

14

longitudinal bore

15

cross hole

16

first support surface

17

second support surface

18

Catch body / ball

19

permanent magnet

20

permanent magnet

21

electromagnet

22

armature

23

solenoid

24

core area

25

Connectors

26

Contact surface at the core area

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102009010949 A1 [0002, 0004, 0012]
• DE 102004021376 A1 [0002]
• DE 19611641 C1 [0003, 0028]
• DE 102007010149 A1 [0003]
• DE 102008020892 A1 [0004]
• DE 102008020893 A1 [0004]
• DE 102007010156 A1 [0012]

Claims (10)

Electromagnetic actuator ( 1 ) with a housing ( 10 ), an electromagnet ( 21 ), an actuator pin ( 8th . 9 ) between one in the housing ( 10 ) retracted rest position and one from the housing ( 10 ) extended working position movable in the housing ( 10 ) and a spring means ( 11 ) is subjected to force in the extension direction, a detent and with the Aktuatorstift ( 8th . 9 ) cooperating by means of detent locking pin ( 12 . 13 ), the actuator pin ( 8th . 9 ) holds in the rest position with locked detent and in the direction of movement of the actuator pin ( 8th . 9 ) is displaceable relative to this, wherein a the Aktuatorstift ( 8th . 9 ) facing away from the head portion of the locking pin ( 12 . 13 ) with a two-pole magnetized in the direction of travel permanent magnet ( 19 . 20 ) is provided and when energized electromagnet ( 21 ) forming the first magnetic circuit the locking pin ( 12 . 13 ) is displaced in the retraction direction in order to release the detent, characterized in that, when the electromagnet is de-energized ( 21 ) forming the second magnetic circuit the locking pin ( 12 . 13 ) is subjected to force in the extension direction to lock the detent. Adjusting device according to claim 1, characterized in that the head portion of the locking pin ( 12 . 13 ) at the electromagnet ( 21 ) facing away from the permanent magnet ( 19 . 20 ) with a magnet armature ( 22 ), wherein in the rest position of the Aktuatorstifts ( 8th . 9 ) the magnet armature ( 22 ) so to the housing ( 10 ) and the permanent magnet ( 19 . 20 ) so to the electromagnet ( 21 ) spaced apart that when energized electromagnet ( 21 ) acting in the extension direction magnetic attraction between armature ( 22 ) and housing ( 10 ) greater than the force acting in the retraction magnetic attraction between the permanent magnet ( 19 . 20 ) and electromagnet ( 21 ). Adjusting device according to claim 2, characterized in that the magnet armature ( 22 ) has the shape of a truncated cone tapering in the extension direction, the outer jacket of which in the rest position of the actuator pin ( 8th . 9 ) spaced by an air gap to a frusto-conical inner shell portion of the housing ( 10 ) runs. Adjusting device according to claim 2, characterized in that the polarity of the permanent magnet ( 19 . 20 ) is aligned so that when energized electromagnet ( 21 ) the permanent magnet ( 19 . 20 ) and the electromagnet ( 21 ) with the same poles, wherein the force acting in the retraction magnetic repulsive force between armature ( 22 ) and housing ( 10 ) greater than the force acting in the extension direction magnetic repulsive force between the permanent magnet ( 19 . 20 ) and electromagnet ( 21 ). Adjusting device according to claim 4, characterized in that two actuator pins ( 8th . 9 ) and two locking pins ( 12 . 13 ) with opposite polarity in the direction opposite polarity aligned permanent magnets ( 19 . 20 ) are provided and the electromagnet ( 21 ) the permanent magnet ( 19 . 20 Assigned together and formed to form the first magnetic circuit with reversible direction of action is such that the first magnetic circuit in one direction of action the locking pin ( 13 ) in the retraction direction and the further locking pin ( 12 ) in the extension direction and that the first magnetic circuit in the other effective direction of the locking pin ( 13 ) in the extension direction and the further locking pin ( 12 ) moved in the retraction direction. Adjusting device according to claim 1, characterized in that the detent has the following features: • one in Aktuatorstift ( 8th . 9 ) extending longitudinal bore ( 14 ) for receiving the locking pin ( 12 . 13 ) and one or more of the longitudinal bore ( 14 ) intersecting transverse bores ( 15 ), • one on the locking pin ( 12 . 13 ) formed first support surface ( 16 ) and one in the housing ( 10 ) formed second support surface ( 17 ), wherein at least one of the support surfaces ( 16 . 17 ) inclined relative to the direction of travel, and • latching body ( 18 ) in the transverse bores ( 15 ) and in the rest position between the support surfaces ( 16 . 17 ) are clamped. Adjusting device according to claim 6, characterized in that three locking bodies designed as balls ( 18 ) and three evenly over the circumference of the Aktuatorstifts ( 12 . 13 ) distributed transverse bores ( 15 ) are provided. Adjusting device according to claim 7, characterized in that the balls ( 18 ) self-locking between the support surfaces ( 16 . 17 ) are clamped, wherein the support surfaces ( 16 . 17 ) have a constant or decreasing in the retraction distance from each other. Adjusting device according to claim 8, characterized in that the first support surface ( 16 ) radially tapered in the extension direction and that the support surfaces ( 16 . 17 ) parallel to each other. Adjusting device according to claim 9, characterized in that the support surfaces ( 16 . 17 ) are formed truncated circular.

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