EP2350442B1 - Adjusting system for camshafts of an internal combustion engine - Google Patents

Description

Adjustment system for camshafts of an internal combustion engine with emergency function, comprising a superposition gearbox with a driven by a crankshaft of the internal combustion engine drive element, a camshaft of the internal combustion engine driving output element and an actuating element, by means of a device for applying a variable braking torque for normal operation on the actuating element Can cause relative rotation between the drive element and the output element, wherein in case of failure of the device and / or its control by braking or setting of the actuating element emergency position of the camshaft can be reached and preserved.

Such an adjustment system is in the DE 102 20 687 A1 described. In this adjustment system, an adjusting motor is used, the stator is either fixed to the cylinder head, in which the camshaft is mounted, and whose rotor acts on the drive element of the superposition gear, or the stator is fixedly connected to the drive element, wherein the rotor also on the actuator of the superposition gear acts. The adjusting motor can be designed as a permanent magnet adjustment motor or as a separately excited DC motor. In an adjusting motor designed as a permanent magnet motor whose stator is rotatably connected to the cylinder head of the internal combustion engine, the rotor must be controlled so that it is in stationary operation, ie when a predetermined phase position of the drive element, which is driven by the crankshaft of the internal combustion engine, compared to Output element that drives the camshaft, has reached a predetermined value, at the same speed as the drive element rotates. To adjust the camshaft to "early" or "late", this rotor is momentarily slower or faster than the drive element in rotation, until the desired phase position is reached.

Such, designed as a permanent magnet motor adjusting motor has according to the DE 102 20 687 A1 a self-holding torque, which increases from a central position in both directions of rotation to a maximum and then drops again. The self-holding torque is the maximum torque with which you can statically load a non-energized variable motor without causing a non-uniform but continuous rotation. This self-holding torque may be sufficient to cause an adjustment of the actuating element in a Notlaufposition when the voltage application of the servomotor and / or its control fails. If this self-holding torque is insufficient to set the actuating element, an external braking torque must additionally be applied by a cylinder-head-resistant, mechanically or electrically acting brake. In a stator rotating with the drive element, this cylinder-head-resistant, mechanically or electrically acting brake is even absolutely necessary.

The structure of such as a permanent magnet motor or as a separately excited DC motor servomotor is complicated and requires a complex control. Due to the additionally required cylinder-head-proof, mechanically or electrically acting brake, this construction becomes even more complicated.

Next is from the DE 103 55 560 A1 an adjusting device for a camshaft is known, which has a driven by a crankshaft of the internal combustion engine drive element, a camshaft driving output element and an actuating element, which is acted upon by a brake with a braking force. By a variation of the braking torque on the adjusting element, a relative rotation between the drive element and the driven element can be achieved. The design of the adjusting device allows any phase angle between the drive element and the output element. The brake is considered a non-contact, electromagnetic Brake executed. Preferably, a hysteresis brake is used whose braking torque is independent of the speed.

Further adjusting devices for a camshaft of an internal combustion engine are known from DE 10 2004 043 548 A1 . DE 10 2004 033 522 A1 and DE 10 2006 011 806 A1 known. The adjusting device according to the DE 10 2006 011 806 A1 has a brake system as well as an output side connected to a camshaft on the output side and with the crankshaft of the engine drive side, wherein the superposition gear for adjusting the camshaft dissipates a part of the drive-side energy in the brake system. According to a further feature of this known adjusting device, the brake system is designed as a frictional braking system, wherein the required braking force is generated via a friction lining located in the long-term slip.

The DE 10 2005 037 158 A1 describes an adjustment system for camshafts of an internal combustion engine with emergency function according to the preamble of claim 1.

Against this background, the invention has the object to provide an adjustment system for camshafts of an internal combustion engine with emergency function, which is simple and easy to control.

This object is achieved by an adjustment system according to claim 1. This is in an adjustment system of the type mentioned, comprising a superposition gear with a driven by a crankshaft of the engine drive element, a camshaft of the internal combustion engine driving output element and an actuator, by means of a device for applying a variable braking torque for normal operation on the Actuator can cause a relative rotation between the drive element and the output element, in case of failure the device and / or its control by braking or setting the actuator an emergency position of the camshaft reachable and durable, provided that a lining carrier of the device is axially displaceable and non-rotatably mounted on a shaft supporting the actuator that the braking torque for normal operation means one on the pad carrier against the force of a spring and non-contact, fixed and acted upon with different voltage electromagnet is variable, and that the lining carrier in the failure of the voltage application of the electromagnet and / or its control by the force of the spring against a fixed Gegenreibfläche pressed and thereby the emergency position is adjustable.

In the adjustment system according to the invention therefore no servomotor is required, since the lining carrier, which is non-rotatably connected to the actuator but axially displaceable, is pressed against the fixed Gegenreibfläche in case of failure of the voltage application of the electromagnet and / or its control and thereby the emergency position is set.

In normal operation, the electromagnet is subjected to an electrical voltage which is variable in dependence on the predetermined phase angle between the crankshaft and the camshaft in height, whereby the contact pressure of the spring against the fixed Gegenreibfläche is more or less reduced, so that the actuator can rotate relative to the drive element until the predetermined phase angle is reached.

The superposition gearing according to the invention is designed as a planetary gearing, with an output element consisting of a ring gear, with a drive element consisting of a planetary carrier, with planetary gears and with an actuator consisting of a sun gear, wherein the planet carrier has at least one radially spaced recess, wherein the ring gear has at least one axially projecting, engaging in the recess control nose, and at the circumferentially spaced end faces of the at least one recess stops form for the at least one control nose and represent the extreme adjustment positions of the camshaft relative to the drive element.

These extreme adjustment positions correspond to the maximum phase angle in the "early" and "late" directions, and one of these extreme adjustment positions simultaneously corresponds to the emergency position that is reached when the voltage application and / or the control of the electromagnet fails and the lining carrier by spring force is pressed against a fixed counter friction surface, while the opposite position is reached when the lining carrier is completely by the corresponding voltage application of the electromagnet without contact with the fixed counter friction surface.

In the emergency running position of the lining carrier with the full spring force on the Gegenreibfläche, so that a corresponding braking torque is generated, which causes a constant friction and thus heating when the internal combustion engine in this emergency running position. In order to reduce this frictional heat and the associated wear, can be rotatably supported by the spring force axially opposite to the lining carrier displaceable thrust washer rotatably support the at least one axially aligned control cam in the recess formed in the planetary carrier drive element on the shaft engages and thereby rotatably but axially slidably coupled to the planet carrier, wherein an end portion of a cam surface of the control cam, which corresponds to the Notlaufposition, is formed lowered relative to the cam surface and the at least one control nose on the ring gear in the emergency position receives. By this arrangement, the force acting on the lining carrier spring force and thus the braking torque are reduced, so that upon reaching the emergency position, an overload of the friction lining is prevented by excessive heating.

If the lowered end portion of the cam surface is formed as a ramp, the cooperating control nose on the output element forming ring gear can accumulate upon application of the electromagnet with a corresponding electrical voltage and reversing the forces acting in the superposition gear moments on the ramp to reach the cam surface. As a result, the pressure plate is displaced axially, after which the phase angle between the drive element and the output element can be changed with a constant bias of the spring acting on the lining carrier.

The end region of the cam surface can also be formed as a locking pocket in which the control nose is held securely when reaching the emergency running position even when increased torques, for example breakaway torques, occur. In this case, it is necessary to move the thrust washer axially by external action when the locking of the control nose is to be lifted at the ring gear in the locking pocket.

In a second embodiment of the adjusting system according to the invention, the electromagnet is arranged with respect to the lining carrier and the counter friction surface, that in normal operation acting between the lining carrier and arranged on one side of the lining carrier Gegenreibfläche braking torque by applying the electromagnet with a variable voltage to the complete concerns of Pad carrier produced at the Gegenreibfläche against the force of the spring and the braking torque for the emergency position in case of failure of the voltage application of the electromagnet and / or its control by pressing the pad carrier through the spring force against a arranged on the other side of the lining carrier, fixed Gegenreibfläche is generated.

Accordingly, in both variants only one electromagnet which can be acted upon by a variable voltage is required in order to generate the braking torque which can be changed for the adjustment of the phase angle, while the braking torque required for reaching the emergency position is brought about by a spring force.

Fig. 1

eine schematische Schnittdarstellung eines erfindungsgemäßen Verstellsystems gemäß einer ersten Ausführungsform,

Fig. 2

eine perspektivische Ansicht eines als Planetenträger in einem Planetengetriebe ausgebildeten Antriebselements,

Fig. 3

eine perspektivische Ansicht eines als Hohlrad in einem Planetengetriebe ausgebildeten Abtriebselements,

Fig. 4

eine erste Ausführungsform einer Druckscheibe im Verstellsystem gemäß Fig. 1,

Fig. 5

eine zweite Ausführungsform einer Druckscheibe in einem Verstellsystem gemäß Fig. 1. und

Fig. 6

eine schematische Schnittansicht einer Ausführungsform eines nicht erfindungsgemäßen Verstellsystems.

The invention will be explained below with reference to two illustrated in the drawings embodiments. In the drawing shows

Fig. 1

FIG. 2 is a schematic sectional view of an adjustment system according to the invention according to a first embodiment, FIG.

Fig. 2

a perspective view of a trained as a planetary carrier in a planetary gear drive element,

Fig. 3

a perspective view of a trained as a ring gear in a planetary gear output element,

Fig. 4

a first embodiment of a pressure plate in the adjustment system according to Fig. 1 .

Fig. 5

a second embodiment of a pressure plate in an adjustment according to Fig. 1 , and

Fig. 6

a schematic sectional view of an embodiment of a non-inventive adjustment system.

The adjustment system according to Fig. 1 comprises a trained as a planetary gear superposition gear with a ring gear 1, which forms the output element, with a planet carrier 2 with a sprocket for connecting the same with a crankshaft of an internal combustion engine by means of a Roller or toothed chain, which forms the drive element, with planetary gears 3 rotatably mounted on bearing axles 23 and with a sun gear 4 mounted on a central shaft 5 as an actuating element. Via the output element 1, a camshaft 21 is driven in the cylinder head of the internal combustion engine. For this purpose, the output element 1 is rotatably connected to the camshaft 21 by means of a screw.

A stationary component 6 of the internal combustion engine, which may be part of the cylinder head, carries a counter friction surface 7 which cooperates with a lining carrier 8 provided with a friction lining 9. The lining carrier 8 is rotatably mounted on the shaft 5 against the force of a spring 10 which is formed in the illustrated embodiment as a plate spring, and mounted axially displaceable against a stop 28.

The axial displacement of the lining carrier 8 is effected by an electromagnet 11 which is fixedly arranged in the component 6. The formed on the shaft 5 stop 28 limits the axial movement of the pad carrier 8 upon application of the electromagnet 11 with a voltage such that no contact and thus no friction between the pad carrier 8 and the electromagnet 11 occurs.

A thrust washer 12 is rotatably supported by means of a rolling bearing 19 on a rotationally fixed sleeve 17, wherein the sleeve 17 is axially displaceable by the force of the spring 10 on the shaft 5. The thrust washer 12 engages with diametrically opposed control cam 13 in circular arc-shaped recesses 15 of the drive element 2 a. The extent of the control cam 13 in the circumferential direction corresponds to the extension of the recesses 15 in the circumferential direction, so that the pressure plate 12 rotates with the drive element 2 substantially free of play, but is axially displaceable.

On the electromagnet 11 facing end face of the ring gear trained output elements 1 diametrically opposite control lugs 16 are arranged, which also engage in the recesses 15. Die Abstützselements 1 sind in der Zeichnung dargestellt. The recesses 15 have end faces 27 which form stops for the control lugs 16, so that the driven element 1 can assume two extreme positions relative to the drive element 2 when the control lugs 16 abut the one or the other end face 27 of the recesses 15. These extreme positions correspond to the maximum displacement angle of the output element 1 relative to the drive element 2 between the positions "late" and "early". One of the extreme positions simultaneously forms an emergency running position.

In the embodiment of the pressure plate 12 according to Fig. 4 ends a cam surface 20 of the control cam 13 in a formed as a locking pocket 22 lowering, which receives a control cam 16 in the locking position, so that the output element 1 and the drive element 2 are coupled positively in the emergency position with each other.

In the embodiment according to Fig. 5 the lowering at the end of the cam surface 20 is formed as a ramp 14, each receiving a control cam 16 in the locking position and allows sliding out of the control cam 16 under certain conditions.

The output element 1 and the drive element 2 are mounted on the sun gear 4 by means of rolling bearings 18. The planet gears 3 mesh in a known manner with their teeth on the one hand with the outer toothing of the sun gear 4 and with the internal toothing of the ring gear first

• Solange der Elektromagnet 11 mit keiner elektrischen Spannung beaufschlagt ist oder die Spannungsbeaufschlagung des Elektromagneten 11 oder seine Steuerung ausgefallen sind, wird der Reibbelag 9 am Belagträger 8 durch die Feder 10 gegen die feststehende Gegenreibfläche 7 gepresst. Dreht sich dann das Antriebselement 2, so wird das Sonnenrad 4 auf der Welle 5 durch das Bremsmoment zwischen dem Reibbelag 9 und der Gegenreibfläche 7 festgehalten und die Nockenwelle 21 mit dem Antriebselement 2 gedreht, bis sich die Druckscheibe 12 unter dem Einfluss der Kraft der Feder 10 durch Verschieben der Muffe 17 axial verschieben kann und die Steuernasen 16 in die durch die Rampe 14 gebildete Absenkung oder die Verriegelungstasche 22 eingreifen. Durch die Axialbewegung der Druckscheibe 12 und der Muffe 17 wird die Vorspannung der Feder 10 vermindert und daraus folgt eine Reduzierung des Reibmoments zwischen der Gegenreibfläche 7 und dem Reibbelag 9, so dass bei der jetzt in der erreichten Notlaufposition laufenden Brennkraftmaschine eine verringerte Reibung und damit Abnutzung zwischen der Gegenreibfläche 7 und dem Reibbelag 9 auftritt.

The operation of the adjustment according to Fig. 1 is the following:

• As long as the electromagnet 11 is subjected to no electrical voltage or the voltage application of the electromagnet 11 or his control have failed, the friction lining 9 is pressed on the lining carrier 8 by the spring 10 against the fixed Gegenreibfläche 7. Then rotates the drive member 2, the sun gear 4 is held on the shaft 5 by the braking torque between the friction lining 9 and the Gegenreibfläche 7 and the camshaft 21 is rotated with the drive member 2 until the pressure plate 12 under the influence of the force of the spring 10 can move axially by moving the sleeve 17 and the control lugs 16 engage in the depression formed by the ramp 14 or the locking pocket 22. Due to the axial movement of the thrust washer 12 and the sleeve 17, the bias of the spring 10 is reduced and this results in a reduction of the friction torque between the counter friction surface 7 and the friction lining 9, so that in the now running in the emergency running position running engine reduced friction and thus wear between the counter friction surface 7 and the friction lining 9 occurs.

In order to return to normal operation, when the electromagnet 11 is subjected to a variable voltage, it is according to the embodiment according to Fig. 4 required to move the thrust washer 12 axially in the direction of the lining carrier 8 against the force of the spring 10. This can be done for example in a workshop by an intervention of the service personnel, or by a further coil, which serves only the unlocking.

In the embodiment according to Fig. 5 it is sufficient to act on the electromagnet 11 with a sufficiently high voltage to completely lift the friction lining 9 on the lining carrier 8 of the Gegenreibfläche 7. Due to the resistance torque of the camshaft 21, the output element 1 has the tendency to move relative to the drive element 2 in an angular position, which is opposite to the ramp or the locking pocket 22. This means according to the embodiment Fig. 5 in that the control lugs 16 slide up the ramps 14 and on the cam surface 20 up to the end stop 27 in the recesses 27 of the planetary carrier 2 can move. Intermediate positions can be adjusted by reducing the voltage applied to the electromagnet 11 until a friction torque corresponding to the respective angular position is set between the counter friction surface 7 and the friction lining 9 on the lining carrier 8, which is in equilibrium with the resistance moment of the internal combustion engine Camshaft 21 is located.

The axial displacement of the pressure plate 12 in the emergency position results in a reduced friction torque between the friction lining 9 on the lining carrier 8 and the counter friction surface 7, whereby an overload of the friction lining 9 is prevented by excessive heating. Conversely, the axial movement of the lining carrier 8 is limited by the stop 28 so that it does not come to rest on the pad carrier 8 on the electromagnet 11 when it is acted upon by the maximum electrical voltage and the friction lining 9 is completely lifted off the counter friction surface 7 on the lining carrier 8 , so that no unwanted friction between the lining carrier 8 and the electromagnet 11 may occur. The lining carrier 8 and the spring 10 are mounted directly on the shaft 5, without additional support on the electromagnet 11, which can be further storage between the electromagnet 11 and the shaft 5 can save.

The embodiment according to Fig. 6 has, instead of the pressure plate 12, an additional counter friction surface 24 on the stationary component 6, which is arranged with respect to the counter friction surface 7 on the other side of the lining carrier 8, which carries a friction lining 9 on one axial side and an emergency friction lining 26 on the opposite side ,

The electromagnet 11 is arranged in this embodiment on the side of the counter-friction surface 7 and pulls the lining carrier 8 against the force of the spring 10, which is supported on a stop 25 on the sun gear 4, against the counter-friction surface 7. Also in this case limits a stop 29 on the sun gear 4, the axial displaceability of the lining carrier 8, so that it does not come into contact with the electromagnet 11.

If the electromagnet 11 is de-energized, the spring 10 presses the lining carrier 8 with the emergency friction lining 26 against the stationary counter-friction surface 24, so that the emergency running position of the ring gear 1 or the camshaft 21 is assumed upon rotation of the drive element 2 due to the friction torque occurring thereby. By applying the electromagnet 11 with an adjustable electrical voltage, the friction lining 9 of the lining carrier 8 is pressed more or less strongly against the counter-friction surface 7, whereby, as in the embodiment according to FIG Fig. 1 , a friction torque tuned for adjusting the phase angle of the camshaft 21 to the respective desired phase angle is generated and this phase angle is maintained. The extreme positions of the output element 1 with respect to the drive element 2 are also determined here by recesses 15 in the drive element 2 and control lugs 16 on the output element 1, while intermediate positions by the adjustable by means of the electromagnet 11 braking torque between the friction lining 9 on the lining carrier 8 and the counter friction surface. 7 be determined.

The embodiments according to the FIGS. 1 and 6 to the effect that in case of failure of the voltage application of the electromagnet 11 or its control, a braking torque is generated by the force of the spring 10 with respect to the fixed component 6 of the internal combustion engine, which adjusts the camshaft 21 via the output member 1 in the emergency position. Even if initially an intermediate position of the camshaft 21 is still given by stalling the internal combustion engine, the emergency running position is achieved in a short time when turning the engine by the starter motor, and it is a temporary operation of the internal combustion engine in this emergency position possible.

The invention is not limited to the illustrated embodiments, but extends to all variants of the invention defined by the claims.

Claims (5)

1. Adjusting system for camshafts of an internal combustion engine with emergency running function, comprising a superposition gearing (1, 2, 3, 4) with a drive input element (2) driven by a crankshaft of the internal combustion engine, with a drive output element (1) which drives a camshaft (21) of the internal combustion engine, and with a positioning element (4) by means of which a relative rotation between the drive input element (2) and the drive output element (1) can be effected by means of a device (7, 8, 9, 10, 11) for imparting a braking torque, which is variable for normal operation, to the positioning element (4), wherein in the event of failure of the device (7, 8, 9, 10, 11) and/or of the control thereof, an emergency running position of the camshaft (21) can be attained and held by braking or arresting of the positioning element (4), and a pad carrier (8) of the device (7, 8, 9, 10, 11) is arranged in an axially displaceable and rotationally conjoint manner on a shaft (5) which bears the positioning element (4), and the braking torque for normal operation can be varied by means of a static electromagnet (11) which acts on the pad carrier (8) counter to the force of a spring (10) and contactlessly and which can have a variable voltage supplied to it, and, in the event of failure of the voltage supply to the electromagnet (11) and/or of the control thereof, the pad carrier (8) can be pressed by the force of the spring (10) against a static counterpart friction surface (7; 24) and thus the emergency running position can be set, wherein the superposition gearing (1, 2, 3, 4) is in the form of a planetary gear set with a drive output element (1) composed of an internal gear, with a drive input element (2) composed of a planet carrier, with planet gears (3) and with a positioning element (4) composed of a sun gear, wherein the planet carrier (2) has at least one recess (15) spaced apart radially from an axis of rotation (5), characterized in that
   the internal gear (1) has at least one axially projecting control lug (16) which engages into the recess (15), and wherein end surfaces (27), which are spaced apart in a circumferential direction, of the at least one recess (15) form stops for the at least one control lug (16) and constitute the extreme adjustment positions of the camshaft (21) relative to the drive input element (2), and on the shaft (5) there is rotatably mounted a thrust washer (12) which can be displaced axially oppositely to the pad carrier (8) by the force of the spring (10), the at least one control cam (13) of which thrust washer engages into the recess (15) of the planet carrier (2) and is thereby coupled in a rotationally conjoint but axially displaceable manner to the planet carrier (2), wherein an end region in circumferential terms of a cam surface (20) of the control cam (13), which end region corresponds to the emergency running position, is formed so as to be lowered in relation to the cam surface (20) and receives the at least one control lug (16) on the internal gear (1) in the emergency running position.
2. Adjusting system according to Claim 1, characterized in that the lowered end region is in the form of a ramp (14).
3. Adjusting system according to Claim 1, characterized in that the lowered end region is in the form of a locking pocket (22).
4. Adjusting system according to Claim 1, characterized in that the electromagnet (11) is arranged relative to the pad carrier (8) and the counterpart friction surface (7) in such a way that, during normal operation, the braking torque generated between the pad carrier (8) and the counterpart friction surface (7) by the force of the spring (10) can be varied as far as zero by the supply of a variable voltage to the electromagnet (11) to the point of full lift-off of the pad carrier (8) from the counterpart friction surface (7), and in that, in the event of failure of the voltage supply to the electromagnet (11) and/or of the control thereof, the pad carrier (8) is pressed against the counterpart friction surface (7) by the force of the spring (10), and thus the emergency running position is set.
5. Adjusting system according to Claim 1, characterized in that the electromagnet (11) is arranged relative to the pad carrier (8) and the counterpart friction surface (7) in such a way that, during normal operation, the braking torque that acts between the pad carrier (8) and the counterpart friction surface (7) arranged on one side of the pad carrier (8) is generated by the supply of a variable voltage to the electromagnet (11) to the point of full abutment of the pad carrier (8) against the counterpart friction surface (7) counter to the force of the spring (10), and in that, in the event of failure of the voltage supply to the electromagnet (11) and/or of the control thereof, the braking torque for the emergency running position is generated by virtue of the pad carrier (8) being pressed by the force of the spring (10) against a static counterpart friction surface (24) arranged on the other side of the pad carrier (8).

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