WO2009062780A1

WO2009062780A1 - Electromechanical adjustment system

Info

Publication number: WO2009062780A1
Application number: PCT/EP2008/062817
Authority: WO
Inventors: Jens Schäfer; Falko Arnold
Original assignee: Schaeffler Kg
Priority date: 2007-11-15
Filing date: 2008-09-25
Publication date: 2009-05-22
Also published as: DE102007054546A1

Abstract

The invention relates to an electromechanical adjustment system for an internal combustion engine for adjusting the relative angular position of two shafts, comprising an actuator (05) with a rotor (11), a stator (12) and a driven shaft (06), an actuating member (07) and sealing means (18) for sealing the actuator (05). According to the invention, the sealing means (18) are used to seal the components of the actuator (05) that are stationary in relation to the cylinder head (09) of the internal combustion engine, at least with respect to the rotor (11) of the actuator (05).

Description

Name of the invention

Electromechanical adjustment system

description

The present invention relates to an electromechanical adjustment system for an internal combustion engine for adjusting the relative angular position of two shafts, comprising an actuator with a rotor, a stator and a Ab- drive shaft, an actuator and sealing means for sealing the actuator.

Electromechanical adjustment systems include phasing in internal combustion engines. Phaser in internal combustion engines are preferably used to adjust the opening and closing times of the gas exchange valves (camshaft adjuster) or as phasing for Aktuatorwel- len in variable valve trains. Phase adjusters are arranged in a shaft system. About the drive shaft - z. B. a Nockenwellenkettenrad - drive power is supplied to the shaft system, which by means of the output shaft - z. B. the camshaft - is withdrawn again. The phaser serves as a link between the drive shaft and the shaft to be driven. It allows, in addition to the drive power, to couple mechanical power into or out of the shaft system. As a result, the motion function of the shaft to be driven, which is forced by the drive wheel, can be changed, for example, a phase offset can be realized.

Phase adjusters can be subdivided into two main groups. The first main group include phaser with an actuator, ie a functional unit which engages in the mass flow or energy flow, which is formed for example hydraulically, electrically or mechanically, and rotates with transmission elements of the camshaft adjuster.

The second main group comprises phase adjusters with a separate actuator, ie a functional unit in which the controller output variable Control of the actuator required control variable is formed, and a separate actuator. The second main group has three types. The first design are phase adjuster with a co-rotating actuator and a co-rotating actuator, for example, a highly translational gear, whose actuating shaft can be advanced by a co-rotating hydraulic motor or centrifugal motor and can be reset by means of a spring. The second design includes phasing with a co-rotating actuator and a stationary, motor-fixed actuator, such as an electric motor or an electric or mechanical brake. Such phase adjusters are used in DE 100 38 354 A1, DE 102 05 034 A1 and EP 1 043 482 B2.

The third design includes phase adjuster with a directional combination of the solutions according to the first and second design, for example, a motor-mounted brake, in which a part of the braking power is used to tension a spring, which allows the return adjustment after switching off the brake. This design is used for example in DE 102 24 446 A1, WO 03 098010, DE 103 24 845 A1 and DE 103 17 607 A1.

In systems according to the aforementioned second main group actuator and actuator are connected to each other by means of a control shaft. The connection can be switchable or non-switchable, detachable or non-detachable, free of play or with play and soft or stiff. Irrespective of the design, the adjustment energy can take the form of a provision by means of a drive or a braking power and by utilizing power losses of the shaft system (eg friction) or of inertia or of centrifugal forces. Braking can also be done with full utilization or shared use of the friction of the camshaft. A phase adjuster can be equipped with or without a mechanical limitation of the adjustment range. As an actuating mechanism or actuator, one-stage or multi-stage three-shaft gearboxes or multi-joint or coupling gearboxes of the following types are used in a camshaft adjuster: swashplate gearboxes, Eccentric gearing, planetary gearing, corrugated gearing, cam disc gearing, multi-joint or coupling gearing or combinations of the individual construction types in a multi-stage design.

In the prior art, it is usually customary to arrange the camshaft, actuator and actuator, for example electric motor, in series. As a result, these adjustment systems require a relatively large amount of installation space, which is available only to a limited extent in the engine compartment. The sealing of the actuator relative to the environment is usually carried out by means of a radial shaft seal around the shaft. Alternatively, as described in DE 102 48 355 A1, only stator and PC board can be protected against engine oil by means of plastic extrusion coating or plastic cover film.

To save axial installation space, it is known to arrange the actuator on the rocker side. This has the additional advantage that on the side facing away from the camshaft still a vacuum pump or other unit can be driven. The camshaft-side arrangement of the actuator is possible because there is usually unused space between the actuator and the first camshaft bearing space from previous applications with hydraulic camshaft adjustment available. In hydraulic adjustment systems oil rotary joints and control valves would be placed at this point. An electromechanical adjustment system requires no control valve and no or now a much simplified rotary transmitter (a lubricating oil channel). The arrangement of the actuator on the side of the camshaft requires some changes to the actuator and the actuator. In a concentric actuator solution, the shaft of the actuator must be designed as a hollow shaft so that the camshaft can be performed. This inevitably increases the diameter of the entire actuator. Due to the diameter of the hollow shaft, which must be greater than the diameter of the camshaft to be performed, sliding seals, such as the radial shaft seals used hitherto, are unfavorable, since they bring about a high frictional torque. In addition, it is at a large shaft diameter and high speeds, the maximum at the camshaft adjuster Verstellgeschwindigkeit occur difficult to seal with radial shaft seals, as they have only a very limited life at high peripheral speeds.

If camshaft-side positioning of the actuator is not possible, the installation space length of the entire system can only be reduced by reducing the length of the individual components. This can be achieved, for example, if, as described in DE 10 2004 014 865, the radial flux machine - the roll runner - is replaced by an axial flow machine - a pancake. The disc rotor can be sealed by means of conventional radial shaft seals due to its smaller compared to the above-described hollow shaft diameter shaft diameter. However, even with the pancake an optimization in terms of friction and thus efficiency would be desirable.

The object of the present invention is thus to provide an electromechanical adjustment system with an improved seal of the actuator. The sealants used should have a good sealing effect, are distinguished by a comparatively low frictional torque, have a long service life, and can therefore also be used with camshaft-side arrangement of the actuator.

To solve the object of the invention is an electromechanical adjustment system according to appended claim 1. The electromechanical adjustment system according to the invention is characterized in that the sealing means are used to seal the stationary relative to the cylinder head of the engine components of the actuator. According to a preferred embodiment, the stationary with respect to the cylinder head components of the actuator at least the stator. The stator is defined here as a component which is arranged vertically with respect to the cylinder head and has at least one winding. If the actuator has a commutation serving electronics, this also belongs to the fixed with respect to the cylinder head components. If a so-called "Sensorless" comes for the commutation - Method used, this electronics can be omitted. In this case, only the stator would have to be sealed accordingly.

It has proved to be advantageous if the sealing means are guided through an air gap located between rotor and stator. In this embodiment, it has proven to be expedient if the sealing means have integrated sealing surfaces for sealing against the rest of the actuator housing. The seal can also be done via additional O-rings.

In a further advantageous embodiment, the sealing means can completely envelop the components of the actuator that are stationary in relation to the cylinder head. For example, according to a particularly preferred embodiment, the sealing means may be sprayed around these actuator components. Because the sealing means are part of the corresponding actuator components, a seal can be achieved in a particularly simple manner. In contrast to the former embodiment, it is no longer necessary to introduce a separate sealant over the air gap.

In an advantageous embodiment, the sealing means consist of a non-magnetic or paramagnetic and non-electrically conductive material. In addition, the material used for the sealants should be resistant to the surrounding media. This ensures that the sealant in the air gap between the stator and the rotor does not weaken the torque-generating magnetic field. When using an electrically conductive material, such as aluminum, losses due to eddy currents are to be expected.

According to a preferred embodiment, the use of plastic has proven to be particularly favorable for the sealant. Plastics have all of the required properties described. Plastic elements can also be manufactured inexpensively. As suitable plastics, for example PA66, PPA or PPS can be used. However, it should not be limited to the plastics mentioned. The Ver- Use of other, suitable plastics is quite possible. Furthermore, it is advantageous if the plastic used is glass fiber reinforced. Glass-fiber reinforced plastics have a comparatively low weight with simultaneously high mechanical strength, corrosion and temperature resistance and good wear behavior.

In a further advantageous embodiment, the material thickness of the sealing means in the air gap is between 0.01 mm and 1 mm. In this context, a material thickness between 0.2 mm and 0.5 mm has proven to be particularly useful. A thinnest possible embodiment of the sealing means located in the air gap is advantageous, since in this case, the air gap between the rotor and stator can be correspondingly smaller, which in turn advantageously affects the maximum torque generated by the actuator.

According to an advantageous embodiment, the inventive electromechanical adjustment system serves to adjust the relative angular position of a camshaft and a crankshaft of an internal combustion engine. The actuator can be arranged on the camshaft side according to a further developed embodiment. In this context, an embodiment of the output shaft of the actuator has proved to be favorable as a hollow shaft. By means of the sealing means used according to the invention, even with the comparatively large diameter of the hollow shaft, through which the camshaft must be guided, a seal optimized with respect to friction and thus also with regard to the efficiency can be obtained.

Finally, it has also proven to be advantageous if the actuator is an electric motor. The electric motor may be designed as a pancake motor. In comparison to a use of radial shaft sealing rings as a sealant, less friction occurs in the sealant used according to the invention, which does not ultimately have an advantageous effect on the wear behavior. Further advantages, details and developments of the present invention will become apparent from the following description of preferred embodiments, with reference to the drawings. Show it:

1 shows an electromechanical adjustment system according to the prior art, with an actuator which is arranged on the side facing away from a camshaft of an actuator, in a simplified representation;

2 shows an electromechanical adjustment system according to the prior art, with an actuator which is arranged on the camshaft side facing the actuator, in a simplified representation;

3 shows a sectional view of an actuator used in a first embodiment of the electromechanical adjustment system according to the invention;

Fig. 4 is a view of the detail z of Figure 3;

5 shows the actuator used in a second embodiment of the electromechanical adjustment system according to the invention in a sectional illustration;

Fig.6 is a view of the detail z of Figure 5;

7 shows the actuator used in a third embodiment of the electromechanical adjustment system according to the invention in a sectional representation;

FIG. 8 is a view of the detail z of FIG. 7; FIG. FIG. 9 is a sectional view of the actuator used in a fourth embodiment of the electromechanical adjustment system according to the invention; FIG.

10 is a view of the detail z of FIG. 9th

1 shows an electromechanical adjustment system according to the prior art with an actuator, which is arranged on the side facing away from a camshaft 01 side of an actuator. The electromechanical adjustment system serves as a camshaft adjuster for adjusting the relative angular position of the camshaft 01 with respect to a crankshaft in drive connection with a drive wheel 03. The camshaft adjuster comprises an actuator 05 with an output shaft (not shown) and an actuator 07 with an adjusting shaft 08. As can be seen from FIG. 1, the camshaft 01, the actuator 07 and the actuator 05 are arranged in series. As an actuator 05, for example, an electric motor or a brake can be used. The actuator 05 is mounted on the cylinder head 09 or another engine-fixed part of the internal combustion engine. As actuator 07 is usually a transmission with high translation used. The actuator 07 is attached to the camshaft 01 via a central screw. To seal the actuator relative to the environment mostly radial shaft seals are used.

2 shows an electromechanical adjustment system according to the prior art with an actuator which is arranged on the camshaft 01 facing side of the actuator. The camshaft adjuster in turn comprises the actuator 05 with the output shaft 06 and the actuator 07. An output shaft 06 of the actuator 05 is designed as a hollow shaft. The camshaft 01 is passed through the output shaft 06. By the camshaft side arrangement of the actuator 05 axial space length can be saved. At the same time, the diameter of the entire actuator 05 increases since the output shaft 06 has a larger diameter than in the case of the one shown in FIG. must have written arrangement so that the camshaft 01 can be passed.

FIG. 3 shows a sectional view of an actuator used in a first embodiment of the electromechanical adjustment system according to the invention, wherein only the sections of the individual components lying above a line of symmetry are drawn. In this embodiment, the actuator 05 is arranged on the camshaft side, as also described with reference to FIG. 2. As an actuator 05 is used in the illustrated embodiment, a brushless hollow shaft motor. The hollow shaft motor comprises a rotor 11, a stator 12, as well as an at least for commutation electronics 14 on a circuit board, which are arranged together in a housing 15. The electronics 14 can be dispensed with if the commutation takes place by means of a "sensorless" method The hollow shaft motor is arranged on the output shaft 06 designed as a hollow shaft The output shaft 06 is designed to pass through a camshaft (not shown).

The fixed with respect to the cylinder head components of the hollow shaft motor, in this case the stator 12 and the electronics 14 are sealed by sealing means 18 to be protected from contamination. The sealing means 18 are passed through the air gap located between the rotor 11 and stator 12. A view of the detail z showing the embodiment of the seal can be seen in FIG. It can be seen that the sealing means 18 extends in the axial direction through the air gap and rests against the stator 12. There remains a mechanical air gap between the sealant and the rotor 11, so that the mobility is not disturbed. The sealing means 18 may for example be designed in the form of a plastic sleeve. As plastics, for example, PA66, PPA or PPS can be used. The plastic used should be as glass fiber reinforced as possible. Alternatively, other materials can be used. The materials used should be non-magnetic or paramagnetic, non-electrically conductive and resistant to the surrounding media. The sealing means 18 are sealing elements 20, for example O-rings or in the sealing means 18 integrated sealing surfaces sealed to the housing 15 of the hollow shaft motor 05. Alternatively, the sealing means 18 and the sealing elements 20 can also be produced in a common production step via a plastic 2-component injection molding technique. The sealing element 20 can be designed, for example, as a thermoplastic elastomer.

5 shows the actuator used in a second embodiment of the electromechanical adjustment system according to the invention in a sectional illustration. This embodiment differs from the embodiment shown in FIG. 3 only in that the sealing means 18 are not designed as a separate component, but enclose the stator 12 and the electronics 14 completely, for example in the form of a plastic sheath. The plastic may, for example, be sprayed or poured around the stator 12 and the electronics 14. Instead of plastic, in turn, another suitable material can be used. A view of the detail z, which shows the execution of the seal, can be seen in Fig. 6, wherein the conditions in the air gap evidently do not differ from those in the embodiment of FIG. 3.

7 shows the actuator used in a third embodiment of the electromechanical adjustment system according to the invention in a sectional illustration. In this embodiment, the actuator 05 is arranged on the side facing away from the camshaft of the actuator, as also described with reference to FIG. 1. As an actuator 05 is used in this case, a brushless pancake motor. The pancake motor comprises a rotor 11, a stator 12, as well as the at least commutation electronics 14, which are arranged together in a housing 15.

The stator 12 and the electronics 14 are sealed by sealing means 18. The sealing means 18 are passed through the air gap located between the rotor 11 and stator 12. A view of the detail z showing the embodiment of the seal can be seen in FIG. Again, the sealing means 18 is preferably flat on the stator 12, so that the necessary me- chanical movement gap to the rotor 11 remains. The sealing means 18 may in turn be designed in the form of a plastic sleeve. The sealing means 18 are sealed via sealing elements 20, for example O-rings or sealing surfaces integrated into the sealing means 18, to the housing 15 of the pancake motor. Alternatively, the sealing means 18 and the sealing elements 20 can in turn also be produced in a common production step via a plastic 2-component injection molding technique. The sealing element 20 may be embodied, for example, as a thermoplastic elastomer.

9 shows the actuator used in a fourth embodiment of the electromechanical adjustment system according to the invention in a sectional representation. This embodiment differs from the embodiment shown in FIG. 7 only in that the sealing means 18 are not designed as a separate component, but completely encase the stator 12 and the electronics 14, for example in the form of a plastic encapsulation. Again, instead of plastic another suitable material can be used. A view of the detail z, which shows the execution of the seal, Fig. 10 can be seen.

LIST OF REFERENCE NUMBERS

01 camshaft

02 -

03 drive wheel

04 -

05 actuator

06 output shaft

07 actuator

08 adjusting shaft

09 cylinder head

10 -

11 rotor

12 stators

13 magnet

14 electronics

15 housing

16 -

17 bearings

18 sealants

19 -

20 sealing element

Claims

claims

1. Electromechanical adjustment system for adjusting the relative angular position of two shafts, in particular for an internal combustion engine, comprising an actuator (05) having a rotor (11), a stator (12) and an output shaft (06), an actuator (07) and sealing means ( 18) for sealing the actuator (05), characterized in that the sealing means (18) in relation to the cylinder head (09) of the internal combustion engine fixed components of the actuator (05) against the rotor (11) seal.

2. Electromechanical adjustment system according to claim 1, characterized in that the sealing means (18) are guided by an air gap located between rotor (11) and stator (12).

3. Electromechanical adjustment system according to claim 2, characterized in that the sealing means (18) sealing elements (20), such as O-rings or integrated sealing surfaces, which effect a seal against a housing (15) of the actuator (05).

4. Electromechanical adjustment system according to claim 1 or 2, characterized in that the sealing means (18) in relation to the cylinder head (09) fixed components of the actuator (05) completely envelop.

5. Electromechanical adjustment system according to claim 4, characterized in that the sealing means (18) around the relative to the cylinder head (09) fixed components of the actuator (05) are splashed or poured around.

6. Electromechanical adjustment system according to one of claims 1 to 5, characterized in that the sealing means (18) consist of a non-magnetic or paramagnetic and non-electrically conductive material, and that the material is resistant to the surrounding media.

7. Electromechanical adjustment system according to one of claims 1 to 6, characterized in that the sealing means (18) consist of plastic.

8. Electromechanical adjustment system according to claim 7, characterized in that the plastic is PA66, PPA or PPS.

9. Electromechanical adjustment system according to claim 7 or 8, characterized in that the plastic is glass fiber reinforced.

10. Electromechanical adjustment system according to one of claims 2 to 9, characterized in that the material thickness of the sealing means (18) in the air gap between 0.01 mm and 1 mm.

11. Electromechanical adjustment system according to claim 10, characterized in that the material thickness of the sealing means (18) in the air gap between 0.2 mm and 0.5 mm.

12. Electromechanical adjustment system according to one of claims 1 to 11, characterized in that the waves whose relative angular position from

Adjustment system is affected, a camshaft (01) and a crankshaft of an internal combustion engine are.

13. Electromechanical adjustment system according to claim 12, characterized in that the actuator (05) is arranged on the camshaft side.

14. Electromechanical adjustment system according to claim 13, characterized in that the output shaft (06) of the actuator (05) is a hollow shaft.

15. Electromechanical adjustment system according to one of claims 1 to 14, characterized in that the actuator (05) is a drive or a braking device.

16. Electromechanical adjustment system according to claim 15, characterized in that the actuator (05) is an electric motor.

17. Electromechanical adjustment system according to claim 16, characterized in that the electric motor is a pancake motor.

18. Electromechanical adjustment system according to one of claims 1 to 17, characterized in that in relation to the cylinder head (09) fixed components of the actuator (05) comprise at least the stator (12).