DE10230427A1 - Switching device for crank mechanism of IC engines has coil unit to generate magnetic field for selective switching of locking unit for eccentric device - Google Patents

Abstract

The device has an eccentric device (6,7,8) and a locking unit (10) to achieve a defined turning position of the device in a connecting rod eye (3). A coil unit to generate a magnetic field for selective switching of the locking unit, is located stationary in a crankcase. The magnetic field passes through the movement path of an actuating part, e.g. a locking bolt, of the locking unit. The coil unit has two coil elements, located on either side of a connecting rod area defined by a connecting rod shaft (1) or cover (4).

Description

The invention relates to a switching device for a Crank drive of an internal combustion engine, for setting different Dead center positions of a piston of the same.

Out DE 197 03 948 C1 an eccentric adjusting device is known, which has a arranged in the region of a crank pin bore of a connecting rod, eccentric bearing shell, wherein by pivoting the bearing shell within the crank pin bore the distance of a piston pin axis of the associated Hubzapfenachse the crankshaft within the eccentricity of the bearing shell, is variable. By changing the distance between the piston pin axis and the crank pin axis, it is possible, in particular the top dead center position of the piston - and thus to change the compression ratio. By providing different compression ratios, it becomes possible to better take into account the varying engine operating conditions during operation of a motor vehicle, in particular with regard to exhaust gas quality, efficiency - and in the high load range with regard to the prevention of engine knock.

In the aforementioned conventional Eccentric adjustment is that in terms of the arrangement their foreign and inner surfaces eccentrically formed bearing shell in the crank pin eye of the connecting rod lockable in two extreme positions. The definition of the bearing shell in the respectively desired Extreme position is done by a locking pin, which has a on the connecting rod cover arranged shift lever is actuated. The shifter is about one in the oil pan arranged switching channel in two different locking positions deflected. In a first latching position of the locking pin locks the bearing shell in a position that causes minimum compression ratios. In In a second position, the locking pin locks the bearing shell in a tilted by 180 ° Position providing maximum compression ratios. The pivoting of the bearing shell takes place by acting on the bearing shell Reaction and mass forces.

Out EP 0 438 121 A1 is also known an eccentric adjusting device for the crank mechanism of an internal combustion engine. Notwithstanding the above-described embodiment, an actuation of a locking cup provided for bearing shell fixing takes place here by pressure oil chambers, wherein the oil pressure selectively prevailing in these pressure oil chambers can be applied via separate oil bores provided on the crankshaft side.

The invention is based on the object Switching device for to create a crank mechanism, through which one to change the effective connecting rod length intended pivotal movement of an eccentric shell, on advantageous Way triggered is.

This object is achieved by a switching device for a crank mechanism for setting different dead center positions a piston of an internal combustion engine, with one in the region of a Pleuelauges - preferably the crankpin connecting rod eye - rotatable arranged eccentric and a locking device, which can selectively be brought into a switching state in which a rotation the eccentric is made possible in the connecting rod, wherein the Switching device according to the invention thereby characterized in that a coil device is provided for the selective generation of a magnetic field, for switching the locking device.

This will make it more advantageous Way possible, waiving production-technically complex pressure oil channels, a reliable Switching the locking trigger and thus selectively a Allow rotation of the eccentric in the connecting rod or to prevent.

According to a particularly preferred embodiment the invention, the coil means is arranged stationary in a crankcase. The coil device comprises preferably a plurality of windings dimensioned in such a way that the desired magnetic field sufficiently reliable with the vehicle side available standing supply voltage can be generated.

Preferably, the coil means in the crankcase arranged such that by This generated magnetic field the track area of an actuator the locking device detected. This will make it possible the actuator the locking device directly through the selectively by means of Coil device generatable magnetic field in the respective desired switching position to urge.

A particularly reliable switching of the actuator between two defined switch positions, can according to a particular aspect of the present invention in an advantageous manner be achieved in that the Coil device on both sides of a connecting rod shaft (or connecting rod cover) arranged, coil elements comprises. The coil elements are Preferably aligned such that the field lines the web area the locking device substantially perpendicular to the crank plane push through.

In particular, in connection with the measure described above, the actuating member is preferably arranged so movable in the connecting rod shank, that this depending on the activation state of the two Spulenele ments in the respective desired switching position can be brought.

A particularly long effect of the by the coil means selectively applied magnetic field on the actuator can according to the invention thereby be achieved that the Coil means (in particular a coil core thereof) in such a way bent is formed that itself this extends along the path of movement of the actuator.

The actuator is according to a particularly preferred embodiment of the invention designed as a locking pin. This locking bolt is preferably displaceable substantially parallel to a crank pin axis in the connecting rod shaft or a corresponding portion of the connecting rod cover added. In such an orientation of the locking bolt have the acting as a result of the oscillation of the connecting rod in the locking bolt ground forces no directed in the direction of movement of the locking bolt force components.

The actuator, in particular in its configuration as a locking pin is preferably such trained that this includes permanent magnetic or soft magnetic sections. hereby will it be possible the actuator directly by the action of the selectively generated magnetic field to move. It is possible, both attraction effects and - especially in conjunction with permanent magnetic structures - to use repulsive effects.

The actuator, in particular in one embodiment as a locking pin is, according to a particularly preferred embodiment the invention with an engagement portion of the eccentric engageable. The intended by the eccentric Engagement portion, for example, as a semi-cylindrical recess be formed in an annular flange portion of the eccentric bushing.

It is possible to interact with the actuator Reverse rotation blocking devices to realize the rotational movement of the eccentric allow only in a preferred direction of rotation or at least impermissibly strong Reversing movements prevent the eccentric device.

Advantageously, the coil device dependent on from the current engine operating state or under consideration activated a special operating strategy. Activation of the Coil means can by applying a DC voltage to the corresponding end portions of the winding wires of the coil device take place. Alternatively, it is also possible, the Coil means to apply alternating current, wherein in this Case, the locking device is preferably designed such that this up Based inductive interaction effects the respectively desired switching position occupies. It is possible, Also provide coil arrangements in the area of the connecting rod.

The switching device according to the invention is suitable in particular for the selective rotation of an eccentric bush, the For example, as a crank pin bearing shell in a crank pin connecting rod eye is included.

Further details of the invention will be apparent from the following description in conjunction with the drawing.

Show it:

1 A perspective view of a connecting rod with a arranged in the region of the crank pin bearing, selectively lockable eccentric bushing;

2a An axial section through the arresting device arranged in the connecting rod cover, to explain the locking state in a first full locking position;

2 B A sectional view similar 2a however, with an engaging member placed in a release position;

2e A section through the locking device in a second locking position;

3 A schematic view for explaining the trajectory of the locking device and the arrangement of a bobbin;

4a A schematic representation for explaining the arrangement of a pair of coils with respect to the passing therethrough actuating member of the locking device.

4b A schematic view similar 4a however, with permanent magnetic structures in the area of the locking pin arrangement.

This in 1 shown connecting rod comprises a connecting rod shank 1 , a trained here in trapezoidal design piston pin eye 2 and one of a crankpin side end portion of the connecting rod shaft 1 and a connecting rod cover 4 limited crank pin eye 3 ,

In the piston pin eye 2 is a made of a bearing material piston pin bushing 5 anchored rotatably.

In the crank pin eye 3 is an axially split eccentric bush 6 so pivotally received, that the eccentric bushing 6 selectively around the central axis of the crankpin eye 3 is pivotable.

The eccentric bush 6 forms a on the crank pin of a crankshaft not shown here, usually sitting on a hydrodynamic lubricant film, made of a bearing material, tread 6a , The provision of the lubricant required to form the hydrodynamic lubricant film takes place via oil bores 30 , which depends on the rotational position of the eccentric bushing 6 in the crank pin eye 3 with the connecting rod side provided pressure oil channels are in fluid communication.

The eccentric bush 6 is formed such that the cylindrical crank pin surface formed by this 6a , eccentric to the also by the eccentric bushing 6 formed in the crank pin eye 3 seated eccentric bush outer surface is arranged.

The eccentric bush 6 is in this embodiment in the region of its axial ends each with an annular flange 7 . 8th provided, wherein each pointing in the axial direction outward end face of the annular flange 7 . 8th forms a side guide device in interaction with a crank pin cheek.

The axially divided formed eccentric bushing 6 is through the connecting rod cover 4 in the crank pin eye 3 held together to a bearing bush element.

The ring flanges 7 . 8th are in the region of diametrically opposite circumferential positions with an engagement structure 9a provided with a locking pin arrangement 10 is selectively engageable.

The locking pin arrangement 10 is in this embodiment in an approach 11 of the connecting rod cover 4 added.

The eccentric bush 6 is in this embodiment by the eccentric bushing 6 acting bearing reaction forces in the direction indicated by the arrow symbol P ₁ , pivoting. A pivoting movement of the eccentric bush in the direction indicated by the arrow symbol P ₂ , is immediately after unlocking the eccentric bushing 6 , Prevented by an activated in connection with the release of the eccentric locking mechanism.

Details of the unlocking of the eccentric bush according to the invention 6 in the crank pin eye 3 will be described below with reference to the 2a ; 2 B and 2c described, which are sectional views at the level of in 1 sectional plane A is shown.

In the 2a Locking device shown 12 comprises a locking pin assembly with selectively engageable in a locking position or a release position engaging elements 13 . 14 ,

The engaging elements 13 . 14 are formed as spring-loaded cylinder pin and each have an engagement end portion which selectively with one on the adjacent annular flange 7 . 8th the eccentric bush 6 trained engagement structure 9a can be brought into engagement. In the embodiment shown here, the eccentric bushing side provided engagement structure is substantially semi-cylindrical in the respective annular flange 7 . 8th formed from the outer circumference, radially bulging bulge.

The engaging elements 13 . 14 are by spring devices 15 . 16 biased. The spring devices 15 . 16 are based in this embodiment between the engagement elements 13 . 14 and a central bearing body 17 from. The central bearing body 17 sits in a sliding bush 18 , Which via an electromagnetic actuating mechanism not shown here between the first switching position shown here and in the 2 B and 2c indicated second switching position, is displaceable.

The sliding bush 18 is through one in the connecting rod cover 4 integrated holding device 19 can be fixed in the respective switching position. The holding device 19 includes this holding pin 20 by holding springs 21 radially against a circumferential groove portion of the sliding bushing 18 are crowded. In the Umfangsnutabschnitt two deeper grooves are formed, in which those spring-loaded retaining elements 20 can dip and thus the sliding bushing 18 fix in the axial direction.

The operation of the previously described Arretiereinrichtung carried out by electromagnetic means.

In the in 2a shown switching position is the engagement element 13 with the first ring flange 7 , or with the engaging structure formed therein 9a positively engaged. That over the central body 17 with the first engagement element 13 coupled second engagement element 14 dives so far into the connecting rod cover in this switching position 4 in from that this second engagement element 14 no locking caused. The eccentric bush 6 is in this switch position in the circumferential direction non-rotatable in the crank pin eye 3 locked.

For switching the eccentric bush 6 in a rotated by 180 ° active position is initially the slide bushing 18 in the in the 2 shown shifted position. This is done on the sliding bushing 18 applied by a selectively energized by a coil arrangement magnetic field, a magnetic force, wherein the retaining fingers 20 When a sufficient magnetic force is achieved, in the radial direction, from the circumferential groove of the circumferential bush of the sliding bush, which is lower in this illustration 18 be crowded out. After the sliding bush 18 , which has reached the end position shown here, dip the holding fingers 20 in the upper circumferential groove and fix the slide bushing 18 in the position shown. In this switching position gets the first engagement element 13 out of engagement with the engagement structure 9a in the first ring flange 7 is trained.

The second engagement element 14 is characterized by the between this second engagement element 14 and the central bearing body 17 provided spring device 16 , against a track section 22 urged, in a the connecting rod shank facing the inside of the second annular flange 8th is trained. This raceway section extends over a circumferential angle of about 180 °, starting from an axial projection of the engagement structure 9a to a, relative to the crank pin axis, diametrically opposite circumferential position. At this circumferential position is the in 2c sichtba re, in the second ring flange 8th trained, intervention structure 9b , The spring device 16 is formed such that the spring force applied by these is weaker than that by the retaining fingers 20 on the sliding bush 18 applied axial holding forces. The engagement element 14 sits in this switch position spring loaded on the Laufrababitt 22 on.

At the end of the race track section 22 there is a career level 23 Here's one with the engaging element 14 engaging stop surface forms, and a pivoting movement of the eccentric bushing 6 only in the direction indicated by the arrow symbol P ₁ allows direction of rotation.

Will the eccentric bush 6 rotated by the bearing reaction forces attacking it by 180 °, it can until reaching this position on the raceway section 22 sliding end face portion of the engagement member 14 into the intervention structure 9b to enter, as in 2c is shown.

Once the engagement element 14 into the intervention structure 9b dips is the second ring flange 8th , and over this the entire eccentric bushing 6 in the crank pin eye 3 fixed in the circumferential direction.

To the in 2c must first cancel the slide bushing 18 again in the as in 2a indicated axial position to be moved. This is, as previously in 2 B for the engagement element 14 described, now the engagement element 13 by a magnetic field, under load of the spring devices 15 against a track section 24 urged in the area of a conical shaft facing inner surface of the first annular flange 7 located. This runway section 24 extends from the recognizable here, the engagement element 13 adjacent peripheral portion, up to the in 2a illustrated engagement structure 9a , An inadmissible rotation of the eccentric bush against the in 2 B by the arrow symbol P ₁ indicated direction of rotation is in this case by the at the end of the raceway section 24 analogous to the raceway section 22 trained career level 25 prevented.

It is possible the track section 24 such that this at least one additional career stage 23 forms, in conjunction with the respectively running on it spring-loaded engagement element 14 forms a backstop, by which an inadmissibly wide pivoting back of the eccentric bushing is avoided.

In 3 is the trajectory of the previously described, by the locking pin arrangement 10 formed locking device relative to a bobbin 26 a coil device shown. The bobbin 26 is formed curved so that this the trajectory of the locking pin arrangement 10 sufficiently follows.

In this embodiment, the locking device or the locking pin arrangement emerges 10 over a circumferential angle of more than 120 ° in the through the bobbin 26 selectively generated magnetic field and is thus brought by the magnetic field in the respective desired switching state.

The bobbin 26 is designed as an oil-resistant component and arranged in the lower region of a crankcase or on the side facing away from the combustion chamber of the crank mechanism. The bobbin 26 can be arranged at corresponding sections, for example, the crankshaft bearing caps or an oil pan structure in the lower region of the crankcase via here not shown. The bobbin 26 preferably comprises a soft iron core and is provided with a winding formed from an insulating conductor, so that over the bobbin selectively a magnetic field can be generated, the field lines at least in that of the locking device (locking pin arrangement 10 ) traversed track space aligned substantially perpendicular to the connecting rod pivot plane.

By so struck arrangement, it becomes possible, the locking pin arrangement 10 by activation of the bobbin 26 to this activated bobbin 26 to relocate.

4a shows in the form of a schematic representation by the bobbin 26 caused force on the, here also as a locking pin arrangement 10 trained, locking device. In this embodiment, the left bobbin 26 activated by applying a voltage to the windings and thereby pulls the locking pin arrangement 10 to the left.

To the locking pin arrangement 10 To bring into another operative position of the second bobbin shown in this illustration 27 to be activated.

By appropriate activation of the two bobbin 26 . 27 the arranged in the web region of the locking device coil arrangement, it is possible, for example, in the 2a to 2c shown to bring locking device in the respective blocking position.

Depending on the switching state the locking device can Rotary positions of the eccentric are brought about, the different top dead center and thus different compression ratios to lead.

In 4b an embodiment of the switching device according to the invention is shown, in which the connecting rod associated assembly of the locking or switching device, one with permanent magnetic structures 31 . 32 provided locking pin arrangement 10 includes. By using permanent magnetic structures 31 . 32 It is possible, in addition to tensile and compressive forces on the locking pin arrangement 10 - In particular locking bolts - exercise. In such an embodiment, it becomes possible according to a particular aspect of the present invention to realize particularly high switching forces, since the effective magnet vice versa quadratically decreases with the gap distance and the required switching forces in this embodiment can be provided with a 8 to 16 times weaker bobbin than at the initiation of the magnetic field in a soft magnetic structure. ( 4a ) When using permanent magnetic structures 31 . 32 It is possible to build up through the coils 26 . 27 Built-magnetic field with respect to its time course, as well as to control the orientation of the magnetic field such that the locking pin arrangement 10 is slowed down before reaching the desired effective position. The voltage supply of the coil arrangement can take place in this case, the two coils 26 . 27 are initially activated so that the magnetic fields constructed in this case rectified forces on the locking pin arrangement 10 - Or another switching device - exercise, wherein after the elapse of a matched to the acceleration behavior of the locking pin arrangement, or otherwise on the response of the switching device time, the voltage applied to one of the coils voltage is reduced, and the polarity is reversed (temporary braking magnetic field). After elapse of a further period of time, the coil thus operated can first be completely switched off, and then activated again so that the desired switching state is achieved with sufficient certainty.

1

connecting rod shaft

2

Piston pin boss

3

Crank pin eye

4

connecting rod

5

Piston pin bushing

6

eccentric

6a

Crankpin tread

7

annular flange

8th

annular flange

9a

engagement structure

9b

engagement structure

10

Locking pin arrangement

11

approach

13

engaging member

14

engaging member

15

spring means

16

spring means

17

centrally bearing body

18

bush

19

holder

20

holding body

21

retaining springs

22

Race section

23

Career Level

24

Race section

25

Career Level

26

Bobbin (first)

27

Bobbin (second)

30

oil drilling

31

permanent magnetic structure

32

permanent magnetic structure

Claims (10)

Switching device for a crank mechanism for setting different dead center positions of a piston of an internal combustion engine with - one in the region of a connecting rod eye ( 3 ) rotatably arranged eccentric device ( 6 . 7 . 8th ) and - a locking device ( 10 . 13 . 14 . 18 ) which is selectively switchable into a locking state by which a defined rotational position of the eccentric device ( 6 . 7 . 8th ) in the connecting rod eye ( 3 ) can be brought, characterized by a coil device ( 26 . 27 ) for generating a magnetic field, for selectively switching the locking device ( 10 . 13 . 14 . 18 ). Switching device according to Claim 1, characterized in that the coil device ( 26 . 27 ) is arranged stationary in a crankcase. Switching device according to Claim 2, characterized in that the coil device ( 26 . 27 ) is arranged in the crankcase such that the selectively generated by this magnetic field the track area of an actuator of the locking device ( 10 . 13 . 14 . 18 ) detected. Switching device according to at least one of Claims 1 to 3, characterized in that the coil device ( 26 . 27 ) at least two coil elements ( 26 ; 27 ), on either side of one of a connecting rod ( 1 ) or connecting rod cover ( 4 ) interspersed connecting rod track space are arranged. Switching device according to at least one of Claims 1 to 4, characterized in that the actuating member is actuated by the part of the coil device ( 26 . 27 ) Generated magnetic field can be brought into different switching positions. Switching device according to at least one of Claims 1 to 5, characterized in that the coil device ( 26 . 27 ) extends along the path of movement of the actuator. Switching device according to at least one of claims 1 to 6, characterized in that the actuating member is designed as a locking pin. Switching device according to at least one of Claims 1 to 7, characterized in that the actuating member is displaceable substantially parallel to a crank pin axis in the connecting rod shaft or the connecting rod cover (11). 4 ) is recorded. Switching device according to at least one of claims 1 to 8, characterized in that the actuating member permanent magnetic (31, 32) or soft magnetic sections includes. Switching device according to at least one of Claims 1 to 9, characterized in that the actuating member is provided with a latching engagement portion ( 9a . 9b ) of the eccentric is engageable.