EP1880086B1 - Camshaft adjuster - Google Patents

Abstract

The invention relates to a locking unit of a camshaft adjuster (1) for an internal combustion engine, in which a locking pin (19) establishes a positive connection between an input element and an output element of the camshaft adjuster (1). The input element and/or the output element are formed by means of a plastic part. An insert (26) against which the locking pin (19) rests and which is supported relative to the plastic part in the area of an inner or outer contour is inserted into said plastic part. Providing large-area support of the contours makes it possible to use plastic as a material in spite of the great stress that occurs, particular attention being paid to a good introduction of force into the plastic part.

Description

The invention relates to a camshaft adjuster for an internal combustion engine. Such camshaft adjusters are used to adjust the relative angular position between a drive element such as a drive wheel, which is connected via a traction means such as a chain or a belt in drive connection with a crankshaft of the internal combustion engine, and an output member driving a camshaft. In this way, for example, for an improvement of the emission values, the fuel consumption and the power profile, control times of valve movements of the internal combustion engine can be changed. Such camshaft adjusters have a locking unit with a locking element, which produces a positive connection between the drive element and the output element in an interlocking operating position. As a result, an adjustment angle of the camshaft adjuster can be defined in partial operating ranges of the internal combustion engine, for example during a start of the internal combustion engine or a hydraulic pressure drop or constant power requirement.

For example, it may happen due to engine downtime that the camshaft adjuster is no longer completely filled with oil. After the restart of the engine it takes u. U. for a few seconds, until the adjuster is fully filled with oil again. In this transitional period, there may be problems of the phase reference between the crankshaft and the camshaft without a locking unit. This can cause degraded exhaust levels and / or power levels and have a negative impact on life and noise.

Background of the invention

From the publication DE 197 55 497 A1 is a vane-type camshaft position, in which the drive element is fixedly connected to the drive wheel, while the output element is fixedly connected to the camshaft. The output element carries a piston which is biased on one side by a spring and is acted upon hydraulically in the opposite direction. When the hydraulic pressure falls below a threshold value set by the spring, the spring moves the piston in the direction of the drive element, so that the piston with a projection in the circumferential direction positively enters a corresponding recess of the drive element, whereby a locking effect is achieved. The adjusting movement is oriented here in the axial direction of the camshaft adjuster.

From the publication DE 199 83 890 T1 a locking mechanism is known with which a rotational movement of an output element relative to a drive element can be limited. In this locking mechanism, a radial movement of a locking element takes place.

From the publication DE 197 24 989 A1 is a design of a camshaft adjuster known in which the drive element has an external helical gear and the output element has an internal helical gearing and in accordance with a hydraulic loading axially displaceable actuator with the two aforementioned helical gears for generating an actuating movement is engaged. The output element carries an axially displaceable, spring-loaded hydraulic piston, which has a spur toothing, which is introduced in the locking operating position in the axial direction in a corresponding toothing of the output element.

In an alternative embodiment of the document DE 195 41 769 a lock is not between the drive wheel and camshaft, but rather between the aforementioned actuator, which forms the output element in this case in the context of the invention, and the rotationally fixed to the drive wheel connected drive element. In this locking, the actuating element has a radially hydraulically displaceable projection which can enter into a corresponding recess of the drive element.

From the publication DE 196 23 818 A1 is a camshaft phaser in vane-type construction, in which in a wing formed with the drive element, a locking pin axially displaceable, spring-loaded and hydraulically acted upon in the axial direction. In the locking operating position, the locking element formed as a locking pin occurs in the axial direction with a cone in a corresponding recess of the output element. Between the drive element and locking element is loosely interposed a guide ring which is intended to influence the guiding and sliding properties between the locking element and the drive element.

Further prior art with regard to locking units is for example from the documents DE 196 30 662 A1 . DE 197 00 866 A1 . DE 197 23 945 A1 . DE 197 16 203 A1 . DE 197 00 866 A1 . DE 100 36 546 A1 . DE 199 61 193 A1 . DE 100 39 923 A1 . DE 100 31 974 A1 and DE 100 55 334 C2 known.

From the publication WO 03/076771 A1 It is known to produce components of the camshaft adjuster made of a heavy-duty, non-metallic material with at least one heavy duty plastic, which cost advantages and energy advantages in the production to be achieved. The heavy-duty non-metallic materials are to be manufactured for parts of the control unit, a drive wheel, a stator, covers, sealing rings from one part or integrally. Insert parts such as screws, nuts, bushings and seals u. Like. Can be injected into the heavy-duty plastic, which also thread should be cut or injected directly into the plastic.

Object of the invention

• der Herstellungskosten,
• des Gewichts,
• des eingesetzten Materials,
• des Massenträgheitsmoments,
• der (Dauer-)Festigkeit,
• der Übertragungssteifigkeit und/oder
• der Montage

verbessert ist.The invention has for its object to propose a camshaft adjuster, with respect to

• the production costs,
• of weight,
• the material used,
• the moment of inertia,
• the (permanent) strength,
• the transmission stiffness and / or
• the assembly

is improved.

Summary of the invention

According to the invention the object is solved by the features of independent claim 1. Further embodiments of the invention will become apparent from the dependent claims 2-8.

The present invention is based on the finding that - for example, according to the document WO 03/076771 A1 - The use of a plastic part for the drive element and / or the output element is advantageous. However, according to the prior art, such plastic parts are used exclusively for camshaft adjusters which have no locking unit. Such known non-lockable camshaft adjusters with plastic parts are based on the prejudice of the experts that the forces occurring in the region of a locking unit can not be absorbed by a plastic part, as these, for example due to excessive surface pressures or stresses, to cracks in the plastic part or a failure of the same being able to lead. It should be noted that the plastic parts must have the required mechanical properties in a wide temperature range. For a locking unit is a reduction occurring stresses and surface pressures not or only made possible by the fact that the contact surfaces between locking element and drive element or driven element are increased, since the locking unit and the locking element should have relatively small dimensions, thus resulting in a compact-build camshaft adjuster.

The solution on which the invention is based is based on the use of at least one insert, on which the locking element comes into positive contact with the locking operating position at least in a direction of adjustment. Thus, for the insert, which forms the contact surface with the locking element, specifically a suitable material can be selected, for example an iron, steel, aluminum or a high-strength plastic. The insert can be prepared for the required stress in the area of the mentioned contact surfaces with suitable machining methods. Thus, the insert can be optimally prepared for the contact and the transmission of the locking force between locking element and insert. Furthermore, in the region of an outer surface of the insert, the locking force can be transmitted to the plastic part. In this case, the outer surface of the insert can be designed arbitrarily in order to ensure optimum transmission of the locking force. For example, the outer surface can be increased almost arbitrarily, so that increases a contact area between the insert and plastic part. Furthermore, the contour of the outer surface can be made suitable for the transmission of the locking force.

The drive element according to the invention is a component of the camshaft adjuster whose movement correlates with the drive movement of the crankshaft of the internal combustion engine, while the movement of the output element correlates with the movement of the camshaft of the internal combustion engine. Here, drive and / or output element can be firmly connected to the drive wheel or the camshaft of the camshaft adjuster and thus perform the same rotational angular movements as the drive wheel or the camshaft. Alternatively, drive and / or Output element to be connected to the drive wheel or the camshaft via a geared connection with a suitable transmission or reduction. In the course of an adjusting movement of the camshaft adjuster, the relative angular position between the drive element and output element is changed.

The locking unit according to the invention can completely set in its locking operating position drive and driven element in both directions, specify a game, accomplish a determination only in a direction of adjustment or represent a stop for limiting an actuating movement.

An improved connection and transmission of the locking force results according to a further embodiment of the camshaft adjuster according to the invention, when the insert has an enlarged extension in the direction of the locking force, which may be a rectilinear extent or an extension in a circumferential direction of the camshaft adjuster. In this way, the transmission length and the transfer surface of the locking force can be increased without requiring a special installation space is required transversely to the locking force. By an enlarged extent, for example, an extension is understood in this sense, which is longer than the diameter or a transverse extent of the locking element or a dimension of a contact surface between locking element and insert. The enlarged extent is in particular at least twice, three times or four times the transverse extent of the locking element or its diameter.

According to a further proposal of the invention, the insert transmits the locking force at least partially frictionally on the plastic part. A normal force for such a frictional connection can be achieved, for example, by pressing the insert into the plastic part, in particular under radial compression, via a cross-sectional widening as a result of the locking force occurring, an elastic deformation of insert or plastic part for insertion of the insert into the plastic part and / or movement of the camshaft adjuster be generated. It is also conceivable that the insert via a clamping or fastening element, such as the central screw for producing a compound of the camshaft adjuster with the camshaft, is clamped against the plastic part, whereby the normal force of the frictional engagement is specified. Such a friction, for example, has advantages in a mounting, since the locking position is sensitively adjustable during assembly.

Alternatively or additionally, it is possible that the insert transmits the locking force at least partially positively to the plastic part. By means of such a positive connection, the relative position of the insert with respect to the plastic part can first of all be determined constructively, whereby sensitive adjustments during assembly can be avoided. Furthermore, a positive transmission of the locking force between the insert and plastic part a particularly stiff, u. U. safe and reliable transmission of the locking force safe.

The insert may be releasably connected to the plastic part to a drive or driven element. An integral drive or driven element can be formed in that the insert and the plastic part are materially connected to one another. The material bond can be produced in the form of an adhesive. Alternatively, the plastic part can be sprayed onto the insert, whereby a cost-effective and simple manufacturing process is given at the same time good connection between the insert and plastic part.

Preferably, the insert has outer teeth, projections, ribs or recesses, which positively enter into corresponding counter teeth, projections, ribs or recesses of the plastic part. As a result, power transmission surfaces are created, which are preferably oriented transversely to the direction of the locking force and ensure good power transmission with low surface pressures. In the event that the insert has a large extension in the direction of the locking force or circumferential direction, in a compact design several Teeth of the teeth, projections, ribs or recesses are arranged in the direction of the locking force connected in series.

It may also be advantageous if the insert extends over a circumferential angle of 50 ° to 300 °. In this way, the active surfaces of positive connections can be further increased and / or the surface of frictional contacts can be extended over the circumferential angle. For such large circumferential angle and a design of the insert and the plastic part with corresponding teeth is in principle a toothing of the insert initially due to the finite manufacturing accuracies only in the range of one tooth or fewer teeth on the corresponding counter-toothing of the plastic part. The invention is in this respect based on the finding that plastic has a relatively low modulus of elasticity, so that with a small locking force, the number of contacting teeth increases, so that the force is divided over a large contact area and many teeth, which increases the life expectancy the teeth of plastic can be significantly increased. For a formation of a frictional connection between the insert and the plastic part, the transmittable frictional force can be significantly increased in accordance with the angle of wrap and the elastic deformation of the insert.

According to a particular proposal of the invention, the insert is formed as a circular disk, which in itself is already a rigid, closed ring structure. The annular disc has an axial or radial projection, a toothing o. Ä. Or a recess which cooperates positively at least in a circumferential direction with a projection or a corresponding recess of the plastic part. Due to the positive connection, firstly the assembly of the insert with respect to the plastic part can be predetermined, so that incorrect assembly is ruled out. Furthermore, a reliable transmission of the locking force is ensured by the contact between the projection and the recess. Of this embodiment is also a non-circular outer geometry of the annular disc-shaped Inserts, which can be used in a corresponding internal geometry of the plastic part.

The plastic may be, for example, a thermoset. However, the use of other types of plastic is also conceivable.

Brief description of the drawings

Figur 1

einen Nockenwellenversteller gemäß dem Stand der Technik in einem Längsschnitt;

Figur 2

einen erfindungsgemäßen Nockenwellenversteller mit einem In- sert in einem Querschnitt;

Figur 3

das Insert des Nockenwellenverstellers gemäß Figur 2;

Figur 4

eine alternative Ausgestaltung eines Inserts für einen erfindungs- gemäßen Nockenwellenversteller;

Figur 5

einen Nockenwellenversteller mit einer weiteren Ausführungsform eines Inserts, welches sich über einen Umfangswinkel von unge- fähr 270° erstreckt;

Figur 6

das Insert des Nockenwellenverstellers gemäß Figur 5;

Figur 7

einen Nockenwellenversteller mit einem kreisringscheibenförmi- gen Insert im Querschnitt;

Figur 8

den Nockenwellenversteller gemäß Figur 7 im Halbschnitt in räumlicher Darstellung;

Figur 9

das kreisringscheibenförmige Insert gemäß Figuren 7 und 8 in räumlicher Darstellung;

Figur 10

einen geschnittenen Nockenwellenversteller in räumlicher Dar- stellung und

Figur 11

den Nockenwellenversteller gemäß Figur 10 in einem Halbquer- schnitt.

Further features of the invention will become apparent from the following description and the accompanying drawings in which embodiments of the invention are shown schematically. Show it:

FIG. 1

a phaser according to the prior art in a longitudinal section;

FIG. 2

a camshaft adjuster according to the invention with an insert in a cross section;

FIG. 3

the insert of the camshaft adjuster according to FIG. 2 ;

FIG. 4

an alternative embodiment of an insert for a camshaft adjuster according to the invention;

FIG. 5

a camshaft adjuster with a further embodiment of an insert, which extends over a circumferential angle of approximately 270 °;

FIG. 6

the insert of the camshaft adjuster according to FIG. 5 ;

FIG. 7

a camshaft adjuster with a circular ring-shaped insert in cross section;

FIG. 8

the camshaft adjuster according to FIG. 7 in half section in spatial representation;

FIG. 9

the circular ring-shaped insert according to FIGS. 7 and 8 in spatial representation;

FIG. 10

a sectional camshaft adjuster in spatial representation and

FIG. 11

the camshaft adjuster according to FIG. 10 in a half-section.

Detailed description of the invention

The invention relates to a camshaft adjuster of any type, for example in vane type, axial piston or with a three-shaft or as an eccentric, wherein the adjusting movement is preferably brought about on the basis of a hydraulic actuator or an electric actuator. In the figures, a camshaft adjuster in vane-type construction is shown by way of example only.

A camshaft adjuster 1 has a drive wheel 2, which is connected via a traction means in drive connection with a crankshaft of an internal combustion engine. A housing 3 of the camshaft adjuster 1 is firmly connected to the drive wheel 2 and has a substantially U-shaped half cross section with a base leg 4, which forms a radially outwardly closed lateral surface and two parallel, extending from the base leg 4 radially inwardly extending side legs. 5 6. Radially inwardly formed in the housing 3 with the U-shaped half-section chambers 7, which are bounded in the circumferential direction by radially inwardly projecting extensions or wings 8 of the housing 3, radially outwardly through the base leg 4 and in the axial direction 10th -10 through the side legs 5, 6. The side legs 5 or the housing 3 with the rigidly connected to this drive wheel 2 forms a drive element. 9

Relative to the drive element 9, an output element 11 is rotatably mounted in the housing 3 so as to be limited in terms of rotation about a longitudinal axis 10-10. The output member 11 is connected through a central, axially oriented bore 12 with a camshaft associated with intake and / or exhaust valves. The output element 11 has a cylindrical base body 13, from which radially outwardly into the chambers 7 wings 14 extend. In the circumferential direction on both sides of the wing 14 pressure chambers 15, 16 are formed, which are each assigned to different actuating directions of the camshaft adjuster. The pressure chambers 15, 16 are closed in the axial direction by the side legs 5, 6 and in the in FIG. 2 represented cross section through the inner surface of the housing formed with the base leg 4, the outer surface of the base body 13, the wing 14 and the wing 8. The volume of the pressure chambers 15, 16 is characterized in the course of the adjusting movement of the camshaft adjuster 1 characterized variable that the distance the wings 8, 14 changed in the circumferential direction.

FIG. 1 shows a locking unit 17 which locks in the illustrated locking operating position, the relative rotational angular position between the drive element 9 and driven element 11 about the longitudinal axis 10-10 or sets. For this purpose, the locking unit 17 has a locking element 18, which is designed as a pin 19 in the present case. The pin 19 is guided along an axis which is oriented parallel to the longitudinal axis 10-10, displaceably in a bore 20 of the driven element 11. While in the unlocked operating position of the locking unit 17, the pin is arranged completely in the driven element, in the in FIG. 1 illustrated locking operating position of the pin 19 is extended in the axial direction of the output member 11 so that it extends with a front portion 21 in a corresponding blind hole 22 of the drive element 9, in particular of the side leg 5. The bore 20 is closed in the blind hole 22 opposite end region. The pin 19 has a central bore 23 which extends from the blind hole 22 opposite end of the pin 19 centrally in this.

Via a hydraulic connection 24, a pressure chamber 16 is hydraulically connected to the end face of the front portion 21 of the pin 19, so that a hydraulic pressure in the pressure chamber 16 acts on the pin 19 in the direction of the non-locking operating position. In the blind hole 23 of the pin 19 extends a compression spring 25 which is supported in an end region on the pin 19 and is supported in the opposite end region at the bottom of the bore 20. For a pressure drop in the pressure chamber 16 and thus the hydraulic connection and in the region of the end face of the front portion 21, the compression spring 25 acts on the pin 19 in the direction of the locking operating position in which the pin 19 enters the blind hole 22.

Further details on the basic operation of a camshaft adjuster 1 are the document WO 01/02703 A1 to be taken from the applicant.

According to FIG. 2 an insert 26 is arranged in the drive element 9, inserted or inserted into this, which in detail in FIG. 3 is shown.

The insert 26 has an approximately annular segment-shaped geometry with a circular segment-shaped or partially cylindrical inner contour 27, a concentric part-circular or partially cylindrical outer contour 28 and radially oriented or transverse to the contours 27, 28 oriented end faces 29, 30. The outer contour 28 is with a toothing 31 provided with teeth with any of the known tooth geometries, here Trapezzähnen provided. The insert 26 is in the viewing direction according to FIG. 2 inserted into the output element 11 and extends in the circumferential direction about the longitudinal axis 10-10. For such insertion, the output element 11 has a recess 33, whose cross section is formed corresponding to the inner contour 27, outer contour 28 and end face 30. The toothing 31 is in engagement with a corresponding toothing of the output element 11. In the circumferential direction, the locking element 18 is supported on the end face 29 of the insert 26, wherein the lateral surface of the front portion 21 of the pin 19 comes to rest against the end face 30.

Notwithstanding the embodiment of the insert 26 according to FIG. 3 the end face 29 can be designed to increase the contact surface with the front region 21 in accordance with the locking element, for example, curved. Alternatively, the insert in the area of the end face via a bore vertically to the plane according to FIG. 3 such that an "eye" is formed into which the pin 19 enters, so that the bore completely surrounds the pin 19 and provides a contact surface in several directions. The insert 26 is arranged in the circumferential direction opposite to the hydraulic connection 24.

FIG. 4 shows an alternative embodiment of the insert 26a, for which the inner contour 27 is also provided with a toothing 32 which can come into engagement with a suitable counter-toothing of the output element 11. For the in FIGS. 3 and 4 illustrated embodiments, the insert 26, 26a extends over a circumferential angle of between 45 ° and 90 °, in particular between 50 ° and 70 °.

An alternative embodiment of the insert 26b is in the FIGS. 5 and 6 shown. The insert 26b extends in this case over a circumferential angle of about 270 °. Such an insert 26b may also have a toothing 31b, 32b in the area of the inner and / or outer contour 27b, 28b. In the FIGS. 5 and 6 However, an insert 26b is formed without such a toothing. In the end region 29b opposite the end face 29b has the insert 26b in the region of the inner contour 27b, a radial recess 34 into which a corresponding projection of the output element 11 enters to secure the insert 26b against displacement in the circumferential direction. If the insert 26b is acted on by a locking force by the pin 19, it may in an elastic embodiment of the insert 26b and / or the output element 11 to a conditioning of the insert 26b in the area the outer contour 28b and / or come in the region of the inner contour 27b to the boundary of the recess 33, whereby the backup of the insert 26 is supported by frictional forces occurring.

FIGS. 7 to 9 show an insert 26c, which is formed substantially in the form of a circular disk with an approximately rectangular half-section 35. In this case, the insert 26c has the hydraulic connection 24c, which opens into the pressure chamber 16 and acts on the pin 19 in the opposite end region. The insert 26c completely surrounds the front portion 21 of the pin 19 in the locking operative position. Furthermore, the insert 26c may have a depression or recess 37 in the region of the outer circumferential surface 36, which engages in a corresponding lug of the driven element 11 for preventing rotation of the insert 26c and / or for guaranteeing faultless installation of the insert 26c.

FIGS. 10 and 11 show the application of the pin 19 with a hydraulic means via a central bore 38 of the camshaft adjuster 1 and a radially oriented side channel 39 which connects the bore 38 hydraulically with the end face of the pin 19.

According to the in FIG. 1 illustrated embodiment, the side legs 5, which forms the drive element 9, not integrally formed with other components of the housing 3, but formed as a kind of sealing lid, which consists in the present case of plastic and the insert 26 receives. The output element 11 is preferably a metal component. It is beneficial to use a material which has a lower coefficient of expansion than the plastic used. By means of such a material, in particular in the case of a plastic unit consisting of a drive wheel, a stator, a cover in the shape of the lateral leg 5, favorable compressive internal stresses are obtained at higher operating temperatures in the transition region between the stator and the cover. This is important because plastics allow only very low tensile strength compared to compressive strength, especially when using a thermoset. You can feel that way make use of apparently negative coefficients of expansion.

Alternatively or additionally, the compressive residual stresses can be generated by a distortion of the components during assembly.

The insert is preferably made of a steel part, a sintered part, a hard metal part or a ceramic component. In the event that the insert is formed as a circular disk, it is possible that this is pulled over the central screw of the camshaft adjuster or via another connecting element such as a screw on the plastic part. This application is suitable for high loads and uses for uniform load application of the locking element, the contact surface and the coefficient of friction between plastic and insert. The efficiency of this combination is enhanced by the bond between screw plug and connector and insert, in which the plastic is sandwiched between the two friction partners.

LIST OF REFERENCE NUMBERS

1

Phaser

2

drive wheel

3

casing

4

base leg

5

side leg

6

side leg

7

chamber

8th

wing

9

driving element

10

longitudinal axis

11

output element

12

drilling

13

body

14

wing

15

pressure chamber

16

pressure chamber

17

locking unit

18

locking element

19

pen

20

drilling

21

Front area

22

Blind hole

23

Blind hole

24

Hydraulic connection

25

compression spring

26

insert

27

inner contour

28

outer contour

29

face

30

face

31

gearing

32

gearing

33

Recess output element

34

Recess insert

35

Hemisection

36

lateral surface

37

recess

38

drilling

39

side channel

Claims (4)

1. Camshaft adjuster (1) for an internal combustion engine, having a locking unit (17) which, in its locking operating position, fixes an adjustment angle of the camshaft adjuster (1) by virtue of a locking element (18) producing, at least in one adjusting direction, a positively locking connection between a drive input element (9), which is drive-connected to a crankshaft of the internal combustion engine, and a drive output element (11), which is drive-connected to a camshaft of the internal combustion engine, characterized in that the drive input element (9) and/or the drive output element (11) is formed with a plastic part and has an insert (26) with which the locking element (18) comes into contact at least in one adjusting direction in the locking operating position and whose outer surface (outer contour 28, inner contour 27) transmits the locking force to the plastic part, the insert (26) transmits the locking force at least partially in a non-positively locking fashion or at least partially in a positively locking fashion to the plastic part, with the insert (26) extending over a circumferential angle of between 50° and 300°.
2. Camshaft adjuster (1) according to Claim 1, characterized in that the insert (26) has an enlarged extent in the direction of the locking force.
3. Camshaft adjuster (1) according to one of Claims 1 or 2, characterized in that the insert (26) has external toothings (31; 32), projections, ribs or recesses which engage in a positively locking fashion into corresponding mating toothings, projections, ribs or recesses of the plastic part.
4. Camshaft adjuster according to one of Claims 1 to 3, characterized in that the insert (26) is designed as an annular disc with a projection or a recess (37) which interacts in a positively locking fashion in at least one circumferential direction with a projection or a depression of the plastic part.

Images