CAMSHAFT ADJUSTER

Abstract

A camshaft adjustment device for an internal combustion engine, having a stator (1) that can be driven by a crankshaft of the internal combustion engine, having a rotor (3) that can be connected rotationally conjointly to the camshaft, having working chambers which are arranged between the stator (1) and the rotor (3) and which are divided into first and second pressure chambers (A, B) by vanes (18) assigned to the rotor (3), wherein, in the rotor (3) there are provided first pressure medium ducts (5) which issue into the first pressure chambers (A) and second pressure medium ducts (6) which issue into the second pressure chambers (B), wherein the rotor (3) has an inner ring (15) and an outer ring (14) which are connected to one another by means of a disk-shaped web (9), and the first pressure medium ducts (5) are arranged on one side of the web (9) and the second pressure medium ducts (6) are arranged on the other side of the web (9), and the first and second pressure medium ducts (5,6) are formed by pressure medium guiding sleeves.

Description

The present invention relates to a camshaft adjuster.

BACKGROUND

Camshaft adjusters are used in modern internal combustion engines for optimizing the consumption and performance values and are used to change the opening and closing points in time of the gas exchange valves. For this purpose, the camshaft adjuster includes a stator which is drivable by the crankshaft and a rotor which is rotatably fixedly connectable to the camshaft. Working chambers, to which a pressure medium may be applied and which are divided into oppositely acting pressure chambers by vanes assigned to the rotor, are provided between the rotor and the stator. During the operation of the internal combustion engine, both pressure chambers are permanently filled with pressure medium, so that the rotor and the stator are connected to each other relatively rigidly. The control times of the gas exchange valves are then changed, in that the pressure is increased in one of the pressure chambers, while the pressure is reduced in the other pressure chamber. For this purpose, the pressure medium must be supplied to the one pressure chamber and removed from the other pressure chamber. To avoid causing the system to vibrate, the inflow of the pressure medium must, in principle, be controlled by the outflow of the pressure medium.

Pressure medium channels must furthermore be provided in the rotor, which empty from the hub of the rotor into the pressure chambers of the rotor. The pressure medium channels are fluidically connected in two groups each to two annular spaces, which are provided radially internally on the rotor, and are separated from each other pressure medium-tight and to which pressure medium may be applied with the aid of a central valve. For this purpose, the central valve includes a spring-loaded valve body, which is movably situated in a control sleeve and which is movable against the spring force with the aid of an actuator in the control sleeve. A complex geometry of control edges is provided in the control sleeve, with the aid of which the pressure medium flowing through the valve body flows out into the annular spaces, the pressure medium channels and finally into the pressure chambers. For this purpose, the valve body has a hollow design and closes and opens certain flow paths using different control edges as a function of its position, so that the pressure medium flows into the first pressure chambers in one position of the valve body and into the second pressure chambers in another position, while it flows out of the respective other pressure chambers into a tank.

The regulating speed of the camshaft adjuster as well as the vibration behavior of the moving parts is greatly dependent on the own weight of the parts, the rotor, in particular, as a particularly large mass, significantly influencing the control behavior. For reasons of use in vehicle manufacturing, it is, in principle, also desirable to use components having a low own weight. For this reason, recesses are already provided in the rotor to the extent permitted by the course of the pressure medium channels.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a camshaft adjuster having a preferably low own weight and a preferably simply structural design.

The present invention achieves the object with the aid of a camshaft adjuster;

The present invention provides that the rotor has an inner ring and an outer ring, which are connected to each other by a disk-shaped web, and the first pressure medium channels are situated on one side of the web and the second pressure medium channels are situated on the other side of the web.

The advantage of the provided camshaft adjuster is to be seen in that the rotor has a significantly lower weight, due to the provided design having the inner ring, the outer ring and the web connecting the inner ring and the outer ring. The pressure medium is supplied separately to the first and second pressure chambers and then through the web, so that the web has the function of separating the pressure medium flows in addition to connecting the outer ring and the inner ring. Furthermore, a prevolume is created for accommodating pressure medium due to the cavities created laterally to the webs, which may be introduced back into the pressure chambers, for example by utilizing the camshaft alternating torques.

It is furthermore provided that the first and second pressure medium channels are formed by pressure medium guiding sleeves. The pressure medium guiding sleeves are much lighter than the solid material previously used, including the pressure medium channels situated therein. Moreover, due to the provided arrangement of the pressure medium guiding sleeves on different sides of the web, a simpler basic structure is achieved, which has a very high rigidity of the rotor, since the web may be preferably situated in the middle between the inner ring and the outer ring. A sufficient clearance for situating the pressure medium guiding sleeves thus remains on both sides of the web, so that they may be situated laterally offset from each other, and annular spaces which are spaced axially apart and are separated from each other pressure-medium-tight may be connected to the pressure medium system. The pressure medium guiding sleeves are furthermore separated from each other by the web, due to the provided arrangement, so that a hydraulic short circuit between pressure chambers A and B may be prevented in the event of possible leakage of the connecting points of the pressure medium guiding sleeves into the openings of the inner ring and the outer ring.

It is furthermore provided that the inner ring and the outer ring are situated concentrically to each other, so that a preferably uniform distribution of mass results with preferably little imbalance. Since the rotor rotates together with the camshaft at a relatively high rotational speed, an imbalance is particularly disadvantageous for the operating life of the camshaft adjuster itself and the operating life of the entire internal combustion engine.

According to another preferred specific embodiment of the present invention, it is provided that the first pressure medium guiding sleeves are situated in a first plane and the second pressure medium guiding sleeves are situated in a second plane. Due to the provided arrangement of the pressure medium guiding sleeves, they may be connected to the pressure medium system with the aid of preferably narrow, annular spaces which are separated from each other pressure medium-tight, a mass compensation being furthermore particularly easy to implement, due to the provided arrangement.

The structure and the mass compensation may be further simplified in that the first plane is situated in parallel to the second plane, and/or the first and second pressure medium guiding sleeves are situated equidistantly from each other in the planes in the circumferential direction.

It is furthermore provided that the first and second pressure medium guiding sleeves are formed by straight tube sections. Due to the provided design of the pressure medium guiding sleeves, the mass distribution may be further simplified. In addition, cost-effective series-production parts may be used.

It is furthermore provided that the first and second pressure medium guiding sleeves have identical masses, whereby the mass compensation may be further simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is explained in greater detail below on the basis of one exemplary embodiment. The following are shown in detail in the figures:

FIG. 1 shows the stator and rotor of a camshaft adjuster according to the present invention;

FIG. 2 shows the rotor in sectional direction A-A; and

FIG. 3 shows an oblique view of the rotor.

DETAILED DESCRIPTION

Apparent in FIG. 1 are a stator 1 and a rotor 3 of a camshaft adjuster according to the present invention, which has a basic structure known from the related art, including stator 1, which is drivable by a crankshaft, and rotor 3, which is rotatably fixedly connected to a camshaft, which is not illustrated. Stator 1 includes a toothing 2 on its outside, with which a drive chain engages, which transmits the rotary motion of the crankshaft in rotation direction “D.” Stator 1 is provided with inwardly directed projections 4, which divide the cavity between stator 1 and rotor 3 into working chambers. The working chambers are further divided into pressure chambers A and B by vanes 18 situated on rotor 3, vanes 18 being supported on stator 1 with their radial outsides with the aid of seals 8. Pressure medium channels 5 and 6 are provided in rotor 3, to which pressure medium is applied by an oil pump with the aid of a central valve, which is not illustrated, or which remove the pressure medium to a tank with the aid of the central valve. Pressure medium channels 5 and 6 empty into pressure chambers A and B, the pressure medium being removed into a tank from pressure chamber A or B to which pressure medium is not applied when pressure is applied to one of pressure chambers A or B by the oil pump.

Pressure medium channels 5 and 6 are each designed as pressure medium guiding sleeves in the form of short, straight tube pieces of equal length and mass. First pressure medium channels 5 empty into first pressure chambers A, and second pressure medium channels 6 empty into second pressure chambers B. In the illustrated exemplary embodiment, rotor 3 includes four vanes 18 and correspondingly four first pressure chambers A and four second pressure chambers B, which are separated from each other by vanes 18. First pressure chambers A and second pressure chambers B differ from each other in that they are situated in groups on the same side of vanes 18, so that rotor 3 is rotated clockwise with respect to stator 1 when pressure is applied, for example to first pressure chambers A.

Rotor 3 is formed from an outer ring 14 and an inner ring 15, which are connected in the middle with the aid of a web 9 in the form of a disk. The disk has a constant width in the radial direction, so that inner ring 15 and outer ring 14 are situated concentrically with respect to each other, as is also apparent in FIG. 3. Radially outwardly directed vanes 18, which divide the working chambers into pressure chambers A and B, are provided on outer ring 14. The disk connects outer ring 14 and inner ring 15 in the middle, so that clearances 7 are present laterally to the disk, as is apparent in FIG. 2. First openings 11 and 13 are furthermore provided in inner ring 15 and in outer ring 14, respectively, laterally to the disk on one side, and second openings 10 and 12 are provided on the other side, into which the pressure medium guiding sleeves are inserted. First openings 13 in outer ring 14 empty into first pressure chambers A, and second openings 12 in outer ring 14 empty into second pressure chambers B in an edge section of outer ring 14 adjacent to vanes 18. First openings 11 and 10 in inner ring 15 empty into annular spaces 17 and 16 provided radially on the inside of inner ring 15, to which pressure medium may be applied with the aid of the central valve, which is not illustrated.

The pressure medium guiding sleeves may preferably be made of steel. Alternatively, pressure medium guiding sleeves made of aluminum or plastic could also be used. The pressure medium guiding sleeves may preferably have a round cross section, but alternatively also an oval, polygonal or even square cross section. The fastening of the pressure medium guiding sleeves on inner ring 15 and on outer ring 14 may take place, e.g., with the aid of a thread, an integral fit, a form-locked fit or a force fit. The pressure medium guiding sleeves preferably all have the same mass and identical dimensions, so that rotor 3 has a preferably minor imbalance, due to an identical arrangement of the pressure medium guiding sleeves in the radial direction and an equidistant arrangement in the circumferential direction.

It is furthermore important that first pressure medium channels 5 and second pressure medium channels 6 formed by the pressure medium guiding sleeves are situated in groups on different sides of web 9, so that a hydraulic short circuit between pressure chambers A and B may be prevented by web 9, even in the event of a possible leak of the connecting points of the pressure medium guiding sleeves in openings 10, 11, 12, 13 of inner ring 15 and/or outer ring 14. Surprisingly, it has furthermore turned out that, due to the laterally offset arrangement of first and second pressure medium channels 5 and 6, it may be ensured that a small remnant of pressure medium always remains in pressure chambers A and B and in the prevolume between outer ring 14 and inner ring 15 or in the pressure medium guiding sleeves, even in the “advance” and “retard” stop positions, so that a small amount of pressure medium is present in the camshaft adjuster even during the cold start phase, which at least reduces uncontrolled movements of rotor 3 with respect to stator 1.

LIST OF REFERENCE NUMERALS

• 1 Stator
• 2 Toothing
• 3 Rotor
• 4 Projections
• 5 First pressure medium channels
• 6 Second pressure medium channels
• 7 Clearances
• 8 Seals
• 9 Web
• 10 First opening
• 11 First opening
• 12 Second opening
• 13 Second opening
• 14 Outer ring
• 15 Inner ring
• 16 Annular space
• 17 Annular space
• 18 Vanes
• A, B Pressure chambers
• D Rotation direction

Claims

1-8. (canceled)

9. A camshaft adjuster comprising:

a stator drivable by a crankshaft;

a rotor rotatably fixedly connectable to the camshaft;

working chambers situated between the stator and the rotor, the working chambers divided into first and second pressure chambers by vanes assigned to the rotor;

first pressure medium channels being provided in the rotor, the first pressure medium channels emptying into the first pressure chambers, and second pressure medium channels emptying into the second pressure chambers;

the rotor including an inner ring and an outer ring connected to each other by a disk-shaped web; and

the first pressure medium channels being situated on one side of the web, and the second pressure medium channels being situated on an other side of the web.

10. The camshaft adjuster as recited in claim 9 wherein the first and second pressure medium channels are formed by pressure medium guiding sleeves.

11. The camshaft adjuster as recited in claim 9 wherein the inner ring and the outer ring are situated concentrically with respect to each other.

12. The camshaft adjuster as recited in claim 10 wherein first pressure medium guiding sleeves of the pressure medium guiding sleeves are situated in a first plane, and second pressure medium guiding sleeves of the pressure medium guiding sleeves are situated in a second plane.

13. The camshaft adjuster as recited in claim 12 wherein the first plane is situated in parallel to the second plane.

14. The camshaft adjuster as recited in claim 12 wherein the first and second pressure medium guiding sleeves are situated equidistantly from each other in the first and second planes in the circumferential direction.

15. The camshaft adjuster as recited in claim 10 wherein the pressure medium guiding sleeves are formed by straight tube sections.

16. The camshaft adjuster as recited in claim 10 wherein the first and second pressure medium guiding sleeves have identical masses.