DE102007049072B4 - Phase adjuster for an internal combustion engine with an Oldham clutch - Google Patents

Abstract

Phase adjuster for adjusting the relative angular position of two shafts, comprising an actuator (05) with an output shaft (19), an actuator (07) with an adjustment shaft (08), which is connected to one of the shafts via an adjustment gear, and one between the output shaft (19) and the adjusting shaft (08) arranged coupling, characterized in that the coupling is an Oldham coupling, the Oldham disc (12) is made of plastic and that the Oldham disc (12) offset four by 90 ° to each other Elongated holes or slots (13) that the ends of the output shaft (19) and the adjusting shaft (08) facing the Oldham disc (12) each have two opposing bolts (15, 16) with the elongated holes or slots (13) Oldham disc (12) are connected, either the bolts (15, 16) used to connect the output shaft (19) or the bolts (15, 16) used to connect the adjusting shaft (08) each have a head sen, through which the Oldham disc (12) is fixed axially.

Description

Field of the Invention

The present invention relates to a phase adjuster for adjusting a relative angular position of two shafts according to the preamble of claim 1.

Such phase adjusters are used in particular in internal combustion engines to adjust the relative angular position of a camshaft relative to a crankshaft and comprise an actuator with an output shaft, an actuator with an adjusting shaft which is connected to the shaft to be adjusted via an adjusting gear, and an arranged between the output shaft and adjusting shaft Coupling.

Phase adjusters in internal combustion engines are preferably used to adjust the opening and closing times of the gas exchange valves (camshaft adjusters) or as phase adjusters for actuator shafts with variable valve trains. Phase adjusters are arranged in a shaft system. About the drive shaft - z. B. a camshaft sprocket - drive power is supplied to the shaft system, which by means of the output shaft - z. B. the camshaft - is withdrawn again. The phase adjuster serves as a link between the drive shaft and the shaft to be driven. In addition to the drive power, it allows mechanical power to be coupled into or removed from the shaft system. As a result, the movement function of the shaft to be driven, which is forced by the drive wheel, can be changed, for example a phase shift can be realized.

Phase adjusters can be divided into two main groups. The first main group includes phase adjusters with an actuator, that is, a functional unit that intervenes in the mass flow or energy flow, which is designed, for example, hydraulically, electrically or mechanically, and rotates with gear elements of the camshaft adjuster. The second main group comprises phase adjusters with a separate actuator, that is, a functional unit in which the control variable required to control the actuator is formed from the controller output variable, and a separate actuator. The second main group has three designs. The first design are phase adjusters with a rotating actuator and a rotating actuator, for example a high-ratio gearbox, the actuating shaft of which can be pre-adjusted by a rotating hydraulic motor or centrifugal motor and can be reset by means of a spring. The second design includes phase adjusters with a rotating actuator and a stationary, motor-fixed actuator, for example an electric motor or an electrical or mechanical brake. In the DE 100 38 354 A1 , of the DE 102 05 034 A1 and the EP 1 043 482 B2 such phase adjusters are used. The third design comprises phase adjusters with a direction-dependent combination of the solutions according to the first and second designs, for example a motor-fixed brake, in which part of the braking power is used to tension a spring, which enables the readjustment after the brake has been switched off. This design is used, for example, by the DE 102 24 446 A1 , WO 2003/098 010 A1 , DE 103 24 845 A1 and DE 103 17 607 A1 used.

In systems according to the second main group, actuator and actuator are connected to one another by means of an actuating shaft. The connection can be switchable or non-switchable, detachable or non-detachable, free of play or with play and soft or stiff. Regardless of the design, the adjustment energy can take the form of provision by a drive or braking power and by utilizing power losses of the shaft system (e.g. friction) or inertia or centrifugal forces. Braking can also take place with full use or joint use of the friction power of the camshaft. A phase adjuster can be equipped with or without mechanical limitation of the adjustment range. Single or multi-stage three-shaft gearboxes or multi-link or coupling gearboxes of the following designs are used as actuating mechanisms or actuator in a camshaft adjuster: a multi-stage version.

In the prior art, it is generally customary to arrange the camshaft, actuator and actuator in series. The actuator is usually attached to the camshaft by means of a central screw. The actuator is attached to the cylinder head, i.e. on the side facing away from the camshaft. Due to the manufacturing tolerances, there is a radial, undesirable axis offset between the output shaft of the actuator and the adjusting shaft of the actuator.

A clutch arranged between the output shaft and the adjustment shaft is intended to transmit the torque from the actuator or the drive torque for the actuating gear and at the same time to compensate for the axial offset between the output shaft and the adjustment shaft.

From the DE 10 2004 041 751 A1 is known a camshaft adjuster, in which the The drive torque is transmitted from an actuating shaft driven by an actuating unit via an intermediate coupling to an adjusting gear. The coupling comprises a first coupling half with a radial extension, which rests against a second coupling half without play in the circumferential direction and is displaceable in the radial direction with respect to the second coupling half. In the DE 10 2004 041 751 A1 An embodiment is described in which the force flow between the extension and the second coupling half takes place via an element that is elastic in the circumferential direction, such as a metal spring or a polymer band. In addition to elasticity in the circumferential direction, the elastic element can also provide an axial elastic connection. As an alternative to using an elastic element, the extension itself can have its own elasticity, so that it itself forms the elastic element. By deforming the elastic element, small axis offsets between the adjusting shaft of the actuating unit and the adjusting gear shaft can be compensated. In addition, a low-noise function is ensured, even if alternating torques occur on the variable-speed gear shaft. However, the central screw cannot be mounted separately when using this known coupling. In addition, the maximum possible axis offsets that can be compensated for are limited. Another disadvantage is that deformations due to axial misalignment and the resulting tensions can destroy the elastic element.

From the DE 103 24 845 A1 a valve timing control device for an internal combustion engine is known. The angular position adjustment between the crankshaft and the camshaft is carried out by a rotary phase control mechanism with an intermediate rotary member, which is adjusted by a brake mechanism with a hysteresis brake. The hysteresis brake comprises a hysteresis ring which has a holding plate. The holding plate is connected to the intermediate rotating member. The intermediate rotating member or the holding plate is provided with a radial groove, while the holding plate or the intermediate rotating member has a projection which is slidably received in the groove in order to move the intermediate rotating member radially relative to the hysteresis ring. As a result, an axis offset of the hysteresis brake to the intermediate rotating element can be compensated. The coupling between the hysteresis brake and the intermediate rotating element works according to the well-known Oldham principle.

Oldham couplings are well known from the prior art, so that an explanation of their basic construction and mode of operation can be omitted here. An Oldham clutch, for example, goes out DE 938 814 B forth. DE 10 2005 018 956 A1 describes an Oldham clutch as part of a camshaft adjuster.

In the prior art, it has been customary to manufacture the Oldham disc from Oldham couplings from steel. However, the use of steel has the disadvantage that the coupling may only have a relatively small amount of play, since otherwise there would be problems in maintaining the required low noise level. In addition, steel has a high density and associated high moment of inertia. Last but not least, steel is also a comparatively expensive material.

The object of the present invention is therefore to provide a phase adjuster with an improved clutch, the clutch being characterized by a low-noise mode of operation and the lowest possible moment of inertia. As few components that can be manufactured inexpensively should be used for the coupling. In addition, the clutch should be able to compensate for comparatively large axial offsets between the output shaft of the actuator and the adjusting shaft of the actuator. Another object of the invention is to enable simple assembly of the camshaft adjuster.

The tasks according to the invention are achieved by phase adjusters according to claims 1 and 2.

The phase adjuster according to the invention is characterized in that the Oldham disc is made of plastic. Furthermore, the Oldham disc has four elongated holes or slots, each offset by 90 ° to one another. In addition, in this embodiment, the ends of the output shaft and the adjusting shaft facing the Oldham disk are connected to the elongated holes or slots of the Oldham disk via two opposing bolts. Either the bolts used to connect the output shaft or the bolts used to connect the adjusting shaft are provided with a head.

There are three different versions for fastening the bolts or the execution of the bolts.

In the simplest design variant, two mutually opposite bores are made in the end faces of the output shaft and adjusting shaft facing the Oldham disk. The bolts are inserted into these holes.

The second design variant uses separate for fastening the bolts Connecting disks, which are attached to the ends of the output shaft and the adjusting shaft facing the Oldham disk. The connecting washers each have two opposite holes for fastening the bolts.

In a third embodiment variant, a drive element is arranged on the end of the output shaft facing the Oldham disk. The bolts used to engage the elongated holes or slots of the Oldham disk are designed as extensions of the drive element in this embodiment variant.

Common to all the design variants described is the use of simple, easy-to-manufacture components. Even the comparatively complex drive element of the third embodiment can be manufactured inexpensively. For example, it can be sintered or, like the Oldham disc, also made of plastic. The use of the drive element also has a positive effect on the moment of inertia.

A major advantage of the solution according to the invention is that the use of plastic for the Oldham disc can achieve a considerable reduction in the mass inertia on the adjusting shaft, since plastic has a significantly lower density than steel. Plastic also has very good damping properties, which ensures a low-noise function of the coupling. Compared to conventional clutches that use Oldham discs made of steel, the coupling according to the invention can have a considerably higher clearance due to the good damping properties of plastic, which not least also leads to a reduction in production costs.

The phase adjuster according to the invention according to claim 2 has an Oldham disc with a central opening through which the central screw can be mounted on the camshaft.

In an advantageous embodiment, the Oldham disc is made of a thermoplastic. Components made of thermoplastic materials can be manufactured extremely inexpensively and are characterized by good performance properties.

Semi-crystalline thermoplastics are suitable for the design of the Oldham pane according to the invention, particularly reinforced polyamides. The latter have high rigidity and strength, as well as extreme impact strength. This makes them extremely robust against mechanical stress. In addition, polyamides have very good sliding properties. For example, the use of glass fiber reinforced polyamide, such as PA 66 GF26, has proven to be expedient.

In a further advantageous embodiment, the Oldham disc has a wall thickness that is adapted to the expected stress. By adapting the Oldham disc thickness to the respective application, a further optimization with regard to the mass or inertia can take place.

Finally, it has also proven to be advantageous if the Oldham washer is provided with ribs. The ribbing enables the Oldham washer to have a high degree of rigidity even with a relatively small wall thickness, and optimization in terms of mass or inertia can be achieved.

• 1 einen Nockenwellenversteller nach dem Stand der Technik in einer vereinfachten Darstellung;
• 2 Bauteile einer bei einem erfindungsgemäßen Phasenwellenversteller verwendeten ersten Ausführungsform einer Kupplung in einer schematischen Darstellung;
• 3 die zusammengebaute Kupplung gemäß 2 in einer schematischen Schnittdarstellung;
• 4 eine zweite Ausführungsform der Kupplung in einer räumlichen Darstellung;
• 5 die Kupplung gemäß 4 in einer Explosionsdarstellung.

Further advantages, details and developments of the present invention result from the following description of preferred embodiments, with reference to the drawing. Show it:

• 1 a camshaft adjuster according to the prior art in a simplified representation;
• 2nd Components of a first embodiment of a clutch used in a phase wave adjuster according to the invention in a schematic representation;
• 3rd the assembled coupling according to 2nd in a schematic sectional view;
• 4th a second embodiment of the coupling in a spatial representation;
• 5 the clutch according to 4th in an exploded view.

1 shows a camshaft adjuster for an internal combustion engine according to the prior art in a simplified representation. The camshaft adjuster is used to adjust the relative angular position of a camshaft 01 versus one with a drive wheel 03 crankshaft in drive connection. The camshaft adjuster includes an actuator 05 with an output shaft (not shown) and an actuator 07 with an adjustment shaft 08 .

Between the output shaft and the adjusting shaft 08 a clutch (not shown) is arranged. How 1 can be seen are camshaft 01 , Actuator 07 and actuator 05 arranged in a row.

As an actuator 05 For example, an electric motor or a brake can be used. Of the Actuator 05 is on the cylinder head 09 or another part of the internal combustion engine fixed to the engine. As an actuator 07 a gearbox with a high gear ratio is mostly used. The actuator 07 is on the camshaft 01 attached via a central screw, not shown.

Due to the motor-fixed mounting of the actuator 05 and the camshaft-fixed assembly of the actuator 07 Due to the manufacturing tolerances, an axis offset occurs between the output shaft of the actuator 05 and the adjusting shaft 08 of the actuator 07 . Furthermore, the camshaft is subject to radial operational vibrations when the internal combustion engine is operating. This misalignment must be compensated for by the clutch. The vibrations should not be transferred to the actuator, which must also be prevented by the clutch.

A first embodiment of a clutch used in the phase adjuster according to the invention should be based on 2nd and 3rd are explained. Here shows 2nd the individual components of the clutch and 3rd the assembled clutch in a schematic representation.

The clutch comprises two connecting plates 11 and an Oldham disc 12 . In the Oldham disc 12 are four slots or slots offset by 90 ° to each other 13 brought in. The Oldham disc 12 consists of plastic, preferably a thermoplastic such as PA 66 GF26. The connecting washers 11 are of the same design in the illustrated embodiment. In the connecting washers 11 are two holes each 14 introduced, which is used to hold bolts 15 , 16 serve. Bolts 15 , 16 differ in that the first bolt 15 are executed without a head and the second bolt 16 are provided with a head. One connecting washer each 11 is on the output shaft of the actuator 05 and the adjusting shaft 08 of the actuator 07 attached. The connecting washers 11 are about the bolts 15 , 16 with the Oldham disc 12 connected. The bolts engage here 15 , 16 in the slots or slots 13 the Oldham disc 12 a. The Oldham disc 12 has a central opening 17th through which the adjustment gear can be attached to the camshaft by means of the central screw. The transmission-side connecting disc 11 must have an opening at least as large for the central screw to pass through.

In 3rd are two sectional views of the coupling rotated by 90 °, so that in Fig. a) the connection of the Oldham disc 12 with the connecting washer 11 towards the output shaft of the actuator using the first bolts 15 and in Fig. b) the connection of the Oldham disc 12 with the connecting disk on the shaft side 11 using the second bolt 16 can be seen.

In the in 3rd illustrated embodiment serve the first bolt 15 to connect the on the output shaft of the actuator 05 arranged connecting disc 11 with the Oldham disc 12 . The second bolts 16 connect those on the adjustment shaft 08 of the actuator 07 arranged connecting disc 11 with the Oldham disc 12 . In that the second bolt 16 are with the head, is the Oldham disc 12 axially to the connecting disc 11 the adjusting shaft 08 bound. In other embodiments, the second bolts 16 also for coupling the connecting disc 11 the output shaft of the actuator 05 with the Oldham disc 12 serve. The Oldham disc 12 in this case would be on the connecting disc 11 the output shaft bound. One between the output shaft and the adjusting shaft 08 Axial misalignment can be caused by the play of the bolts 15 , 16 in the elongated holes or slots 13 the Oldham disc 12 be balanced.

When executing the on the actuator 07 connecting disc to be fastened 11 it should be noted that the inner diameter of the connecting washer 11 must be chosen so large that the central screw can be carried out. The on the output shaft of the actuator 05 connecting disc to be fastened 11 does not have to allow the central screw to be passed through and can therefore be optimized with regard to mass and inertia.

In the 4th and 5 a preferred embodiment of the invention is shown. The Oldham disc 12 is modified in such a way that the slots provided for receiving the connecting disk on the output shaft side 13 down to the central opening 17th the Oldham disc 12 extend. Therefore, instead of the connecting washer in this embodiment 11 also one on the output shaft 19th of the actuator 05 arranged drive element 18th are used. The drive element 18th has extensions 20th on that like the bolts described above 15 the engagement in the elongated holes or slots 13 the Oldham disc 12 serve. A further reduction in the moment of inertia can be achieved by using a comparatively small drive element. Alternatively, the drive element 18th also be made in one piece with the output shaft.

At the in 4th and 5 Version shown shows the Oldham disc 12 Ribs on. Due to these ribs, the mass of the Oldham washer can 12 can be further reduced and a high level of rigidity can be achieved.

Alternatively, the clutch can also be used without connecting plates 11 being constructed. In this case, they are used to fasten the bolts 15 , 16 serving holes in the end faces of the ends of the output shaft of the actuator 05 and adjusting shaft 08 of the actuator 07 brought directly.

Reference symbol list

01

camshaft

02

-

03

drive wheel

04

-

05

Actuator

06

-

07

Actuator

08

Adjustment shaft

09

Cylinder head

10th

-

11

Connecting washers

12

Oldham disc

13

Elongated holes / slots in the Oldham disc

14

Bores in the connecting washers

15

first bolt without a head

16

second bolt with head

17th

central opening in Oldham disc

18th

Drive element

19th

Output shaft

20th

Extensions to the drive element

Claims (14)

Phase adjuster for adjusting the relative angular position of two shafts, comprising an actuator (05) with an output shaft (19), an actuator (07) with an adjustment shaft (08) which is connected to one of the shafts via an adjustment gear, and one between the output shaft (19) and the adjusting shaft (08) arranged clutch, characterized in that the clutch is an Oldham clutch, the Oldham disc (12) is made of plastic and that the Oldham disc (12) offset four by 90 ° to each other Elongated holes or slots (13) that the ends of the output shaft (19) and the adjusting shaft (08) facing the Oldham disc (12) each have two opposing bolts (15, 16) with the elongated holes or slots (13) Oldham disc (12) are connected, either the bolts (15, 16) used to connect the output shaft (19) or the bolts (15, 16) used to connect the adjusting shaft (08) each have a head by which the Oldham disc (12) is fixed axially. Phase adjuster according to the generic term of Claim 1 , characterized in that the shafts are a camshaft (01) and a crankshaft of an internal combustion engine, the adjustment gear being connected to the camshaft (01) via a central screw and in that the Oldham disc (12) has a central opening (17), through which the central screw can be mounted on the camshaft (01). Phase adjuster after Claim 1 or 2nd , characterized in that the actuator (05) is a drive or a braking device. Phase adjuster after Claim 3 , characterized in that the actuator (05) is an electric motor. Phase adjuster according to one of the Claims 1 to 4th , characterized in that the Oldham disc (12) consists of a thermoplastic. Phase adjuster after Claim 5 , characterized in that the thermoplastic is a partially crystalline thermoplastic. Phase adjuster after Claim 6 , characterized in that the thermoplastic is polyamide. Phase adjuster after Claim 7 , characterized in that the thermoplastic is PA 66 GF26. Phase adjuster after Claim 1 or 8th , characterized in that the output shaft (19) and the adjusting shaft (08) each have two mutually opposite bores on their end faces facing the Oldham disc (12), the bolts (15, 16) being inserted into this bore. Phase adjuster after Claim 1 , 8th or 9 , characterized in that a connecting disc (11) is fastened to the ends of the output shaft (19) and the adjusting shaft (08) facing the Oldham disc (12), said connecting discs (11) each having two mutually opposite bores (14) have, the bolts (15, 16) being inserted into these bores (14). Phase adjuster according to one of the Claims 1 or 8th to 10th , characterized in that the output shaft (19) on its the Oldham Disc (12) facing end has a drive element (18), the bolts (15, 16) serving to engage the slots (13) of the Oldham disc (12) being designed as extensions (20) of the drive element (18). Phase adjuster after Claim 11 , characterized in that the extensions (20) are integrally formed on the drive element (18). Phase adjuster according to one of the preceding claims, characterized in that the Oldham disc (12) has a wall thickness which is adapted to the expected stress. Phase adjuster according to one of the preceding claims, characterized in that the Oldham disc (12) has ribs.

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