Patent Application
20160003110
The present invention relates to a stator assembly for a camshaft adjuster, including a stator which preferably has a toothing on its outside for the purpose of absorbing torque provided by a crankshaft, the stator having a wall which preferably integrally forms the toothing and includes a cavity extending in the axial direction for accommodating a rotor, at least one integrally provided flange section of the stator, which protrudes radially inwardly, directly or indirectly forming an axial stop for the rotor.
Stator assemblies of this type are used in camshaft adjusters, which are part of a timing assembly of internal combustion engines. Timing assemblies of this type may include fraction mechanism drives, such as chain and belt drives, for both gasoline and diesel engines. Special camshaft adjusters, in which the stator unit is formed as a single piece from the stator and the cover, are known per se.
Established prior art is known, for example, from DE 10 2010 008 003 A1, in which a cell wheel of a device is described for variably setting the control times of gas exchange valves of an internal combustion engine, which includes a cylindrical peripheral wall. The device furthermore has a drive wheel which is situated on an outer lateral surface of the peripheral wall, a sealing cover, which extends radially inwardly from an inner lateral surface of the peripheral wall, and also has multiple projections, which extend radially inwardly from the inner lateral surface of the peripheral wall and in the axial direction from the sealing cover.
U.S. Pat. No. 6,457,447 B1 furthermore describes a sealing plate in a camshaft adjuster, which, however, abuts both the upper side of the rotor and one side of the stator and is thus in sealing contact with a gear wheel.
In the present prior art, the inner base surface of the stator pot is usually re-machined to meet the high evenness requirements of the axial bearing point. The better the evenness at this point, the more the axial bearing play and thus the leakage may be minimized.
However, processing this surface is complex and, in particular, problematic at the transition between the cover surface and the wall of the stator. Namely, a chamfer or a radius occurs here, due to the special tool geometry. This chamfer or the radius must be provided at the rotor and at the sealing strips, so that the rotor and the stator have a sufficient ease of movement and the adjusting process may be carried out. This inevitably results in a circumferential leakage point on the camshaft adjuster, which, however, should be avoided. A stator assembly should ultimately be provided, which avoids the known disadvantages.
It is an object of the present invention to eliminate the known disadvantages and to provide an economically manufacturable stator assembly, which, in turn, may be used in a hydraulic camshaft adjuster, a leakage simultaneously being effectively avoided.
Complex, re-machining steps of the stator base surface should be avoided.
In a generic stator assembly, this object is achieved by the fact that a spacing washer, which is separate from the stator and from the rotor, is present in the cavity, for example between the stator and the rotor, and is preferably situated in sealing contact with the flange section.
Due to the additional use of a spacing washer which is joined to the stator pot, a complex processing of the stator base surface may be avoided. The spacing washer makes it possible to provide a minimum axial play.
Advantageous specific embodiments are explained in greater detail below.
It is thus advantageous if the spacing washer has at least one recess which extends from the outside to the interior of the spacing washer and which extends approximately in the direction of the center of the spacing washer, the recess being dimensioned and/or provided to establish a form-locked fit with the stator, the stator having at least one inwardly projecting tab for this purpose. In this way, a relative rotation of the spacing washer, which may also be designed as a sealing disk, with the stator may be prevented by using a form-locked fit. A stator assembly which provides the requirements for a precision use may be created thereby. While the preferred connection of the spacing washer to the stator takes place with the aid of a form-locked fit, force-fitted and/or integral connections have other advantages.
If a plurality of approximately rectangular recesses is evenly distributed over the circumference, preferably if 2, 3, 4, 5, 6, 7 or 8 recesses are present, the anti-rotation protection is ensured to a particular extent.
To improve an elasticity of the spacing washer in the radial direction and/or the axial direction, it is advantageous if a central through-opening is provided in the spacing washer and multiple indentations extending in the axial direction are provided between the central through-opening and the outer circumference of the spacing washer.
It is advantageous if the indentations are designed as pockets and/or through-holes. In the case of through-holes, the weight of the spacing washer is also effectively reduced, while the pockets also have a targeted oil conducting effect if oil is used as the hydraulic medium. Other fluids are also conceivable as the hydraulic medium.
It has turned out to be particularly advantageous if the indentations are provided on the side of the spacing washer facing the flange section and/or the pockets are present on the side of the spacing washer facing away from the flange section.
If at least one nub extending in the axial direction, preferably a plurality of evenly distributed nubs, is/are provided in the indentation, the elasticity of the spacing washer, which may also be designed as a sealing disk, pronounced in the axial direction, may be improved. The spacing washer may be manufactured from metallic material, such as a light metal alloy, but also a steel alloy or a plastic material. In addition to the use of plastic or metal for the spacing washer, rubber has also turned out to be sufficiently resilient.
The sealing effect may be improved if a hydraulic medium conducting hole, such as a bore, is provided in the pocket.
It is also advantageous if each pocket is surrounded by a planarly designed, raised edge of the spacing washer/sealing disk, since this also improves the sealing effect.
The present invention also relates to a vane-type hydraulic camshaft adjuster, which includes a rotor and a stator assembly according to the present invention.
It is also advantageous if the spacing washer has a chamfer or rounding (concavity) on its outside, which is adapted to a chamfer or rounding (concavity) existing between the wall of the stator and the transition area between the wall and the flange section. In this way, a manufacturing-related, circumferential chamfer or a corresponding radius on the stator pot may be accepted without requiring any re-machining The stator pot is the integral combination/one-piece design of the stator wall and the flange section(s) of the stator.
The elastic design of the spacing washer in the radial direction for the purpose of adaptation to the stator contour is also advantageous to ensure a circumferentially high sealing function.
It is also effective if the underside of the spacing washer is provided with an elastic profiling, which adapts to the surface and evenness errors of the stator base surface when an axial force is applied.
It is furthermore possible to implement oil channels in the spacing washer for the purpose of supplying the pressure chambers and the locking unit.
The design of the spacing washer with recesses on the underside of the spacing washer for the purpose of implementing a contact force via the oil pressure and thus a minimum axial play during operation is also advantageous.
In other words, a spacing washer is inserted into the stator pot for the purpose of avoiding a complex re-machining of the stator base surface. Due to the separate processing of the spacing washer or also a large number of spacing washers, for example by machining only the spacing washer(s), i.e., with the aid of grinding, a high accuracy of the evenness or the parallelism of the surface may be achieved.
If this spacing washer, which may also be referred to as the sealing disk, is inserted into the stator pot, the evenness errors of the unprocessed stator base are compensated for. The manufacturing-related chamfer at the stator cover transition is caught by a corresponding chamfer on the spacing washer closest thereto. A sharp-edged edge design between the rotor and stator may furthermore be implemented, which results in fewer internal leaks.
The spacing washer may be provided with an elastic design on its outer diameter by removing material. As a result, the spacing washer adapts to the vane running diameter on the stator pot and forms an optimal seal here. Likewise, the circumferential leakage point on a radial bearing may be sealed. Due to the elastic adaptation of the disk to the stator diameter, more approximate manufacturing tolerances of the two individual parts may be allowed, which minimizes the cost pressure.
To compensate for major surface or evenness errors in the stator base, an elastic, finely structured/profiled disk underside surface may be designed. During assembly, the disk is pressed onto the base surface with the aid of a stamp. The profiling is deformed and optimally adapted in the process to the base surface. Due to the elastic resilience of the base structure, a minimum axial play may be implemented. This has a positive effect on leaks.
One additional option of limiting the axial bearing play is to provide the washer with recesses on its back, which fill with oil during operation and thus press the disk against the rotor.
Oil channels for supplying the pressure chambers or the locking unit may also be implemented via the disk.
The present invention is also explained in greater detail below with the aid of a drawing. Different specific embodiments are illustrated.
The figures are only schematic and are used only for the sake of understanding the present invention. Identical elements are provided with identical reference numerals.
Torque is transmitted from a crankshaft to stator 3 via toothing 4, with the aid of a traction mechanism drive, which is not illustrated, such as a chain or belt drive. Toothing 4 is an integral part of wall 6 of stator 3, which is in the form of a stator pot.
Stator 3 has a cavity 7, which extends in the axial direction, flange sections 8 projecting from wall 6 of stator 3 radially inwardly into cavity 7 for the purpose of forming a stop for a rotor 9 and also has a spacing washer 10 connected therebetween. Spacing washer 10 may also be referred to as a sealing disk. Flange sections 8 thus form the base of the stator pot and have a central passage.
The state of contact between rotor 9 and flange sections 8 of stator 3 is also understood to be the intermediate connection of another object.
Spacing washer 10 is situated axially between rotor 9 and stator 3. On its side facing flange sections 8 in the circumferential direction, spacing washer 10 has a chamfer 11, which is adapted to a chamfer 12 of stator 3. The two chamfers 11 and 12 may also be designed as roundings.
Spacing washer 10 is preferably manufactured from plastic and inserted into the stator to minimize the axial play.
Another specific embodiment of a spacing washer is provided in
In another modification, another exemplary embodiment is represented in
As a sealing disk, spacing washer 10 forms a seal to the outside, i.e., so that a loss of hydraulic medium from the interior of stator assembly 1, due to leaks, is prevented.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 203 245.5 | Feb 2013 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2013/200296 | 11/11/2013 | WO | 00 |
