Patent Application
20160312667
The present invention relates to a multipart rotor for a hydraulic camshaft adjuster, which includes a rotor main body that is connected to at least one first rotor secondary body in a rotatably fixed and axially fixed manner, the rotor secondary body defining or determining, at least in sections or completely, a contour of a hydraulic medium-conducting channel.
The rotor main body could also be referred to as a central body or cup-shaped body. The hydraulic medium-conducting channel could also be referred to as an oil channel when pressure oil/oil is used as the hydraulic medium.
Multipart rotors for hydraulic camshaft adjusters of the vane cell type are already known from the prior art. Thus, for example, rotor halves are joined with pins and/or sintered. It is known to mount two plastic rotor parts on a steel support, and to additionally glue two rotor parts which are joined thereto. In addition, rotor parts may ensure a connection by nested geometries that are adapted to one another. Furthermore, it is possible to provide two rotor halves which seal off oil channels via sintered facets. It is also known to design the rotor as a composite system in which a rotor core in addition to a cover forms oil channels. The use of a form fit and a press fit in oil channels is likewise known in principle.
Thus, for example, DE 10 2009 031 934 A1 provides a camshaft adjuster which includes a stator and a rotor, situated in the stator, which includes vanes, each of which is situated in a chamber formed between the stator and the rotor, the vanes dividing their respective chamber into two subchambers, and pressure oil being suppliable to and dischargeable from each subchamber via oil channels, so that the pressure oil may exert a torque on the rotor. Due to this configuration, the rotor is rotatable and adjustable for the camshaft adjustment, the rotor being made of a metallic base structure which includes a plastic liner, axially adjacent thereto, in which at least one of the oil channels is formed.
A two-part rotor is also known from WO 2010/128976 A1 which includes a sleeve part that is concentric with respect to a main body which forms a vane, the hydraulic medium-conducting channels formed as oil channels being present in the sleeve part.
Another hydraulic camshaft adjuster is known from DE 10 2008 028 640 A1. The cited publication describes a hydraulic camshaft adjuster which includes a drivable outer body having at least one hydraulic chamber, and an inner body which is situated internally with respect to the outer body and fixedly connectable to a camshaft, and which includes at least one swivel vane which extends radially into the hydraulic chamber, thus dividing the hydraulic chamber into a first and a second working chamber. The inner body also includes at least one oil supply line and one oil discharge line which extend from a casing interior to a casing exterior of the inner body, up to one of the two working chambers. The inner body is made up of at least one first element and one second element, each of the two elements at mutually facing front sides having a geometry which, together with the respective other element, forms the oil supply line and the oil discharge line of the inner part.
A multipart joined rotor for hydraulic camshaft adjusters having joint sealing profiles is also known from DE 10 2011 117 856 A1. The described camshaft adjusting device for internal combustion engines and a method for manufacturing same relate to a stator wheel and a rotor wheel which cooperates with the stator wheel. The stator wheel is driven in rotation about a rotation axis, the rotor wheel being connectable to a camshaft of the internal combustion engine, and in addition the stator wheel including radially inwardly facing stator vanes, between which radially outwardly facing rotor vanes (which define the vane cells) situated on the rotor wheel extend, so that fluid chambers/working chambers A and B are formed between the stator vanes and the rotor vanes, and which may be acted on with a pressure fluid via fluid channels, the rotor wheel including a first partial body and a second partial body, a joining surface of the first partial body and a joining surface of the second partial body being joined together, and depressions being introduced into at least one of the two joining surfaces in order to form the fluid channels, at least at spaced intervals. To provide a camshaft adjusting device which includes a rotor wheel that is formed from two partial bodies which are joined together, in the cited publication it is provided that the fluid channels are sealed off, and that a defined contact of the brought-together joining surfaces is created.
A camshaft adjuster which operates according to the swivel motor principle, which means that it is able to move back and forth at a certain angle, generally includes a stator and a rotor, as also provided in EP 1 731 722 A1, for example. The rotor itself is provided as a composite system made up of at least two components. One of the components is a cover. The other component of the composite system may be referred to as a rotor core. The cover is placed on the rotor.
Another hydraulic camshaft adjuster is known from WO 2009/1252987 A1.
The rotor in DE 10 2009 053 600 A1 has also proven to be easy to manufacture and robust under load. The cited publication provides a rotor, in particular for a camshaft adjuster, which includes a rotor base body having a hub part with a central oil supply line. At least one vane which is radially situated in the hub part, and an oil channel which extends through the hub part on both sides of a vane and which is fluidically connected to the central oil supply line, is provided in the hub part. The manufacture of the rotor base body is greatly simplified by dividing the rotor base body along a parting line so that it is made up of two base body parts. Journals or pins are inserted for joining the two rotor halves together. The journals are provided at one of the two rotor halves, and engage with recesses in the other rotor half.
However, the previous approaches have disadvantages with regard to costs, for example due to the provision of connecting pins or the need for keeping adhesives on hand which are additionally or exclusively used. In addition, hazardous materials are frequently involved which should be avoided. Furthermore, the connection obtained is often not robust enough for the requirements of the customer. In addition, when longitudinal press fits, heretofore common at certain locations, are used, component deformations occur which should be avoided. Also, there is always a risk of the rotor jamming in the stator. The previous approaches are also not sufficiently secured against leaks. Furthermore, cracks or other component damage may occur during operation which result(s) in failure of the hydraulic camshaft adjuster.
One object of the present invention is to eliminate or at least minimize the stated disadvantages. In particular, one aim is to provide a rotor variant that is cost-effective and easy to manufacture, and also particularly long-lasting.
Caulking is understood to mean a force-fit and form-fit connection which is achieved by plastic deformation, in which, for example, a section of one or the other connection partner or of both connection partners is introduced into a contour, provided for this purpose, of the respective other connection partner, with a plastic deformation step in between.
It is advantageous when rolling is used as caulking.
A novel design principle is thus achievable which allows versatile use of a split rotor in hydraulic camshaft adjusters.
It is advantageous when the rotor main body is caulked to a second rotor secondary body, or the two rotor secondary bodies are caulked to one another. Of course, it is also possible to caulk the two rotor secondary bodies to one another and also to the rotor main body. Corresponding caulking connections are then present. The individual parts are then permanently, nondetachably connected to one another. The quality of the connection is also easily verifiable, resulting in a low failure rate during operation. The load-bearing capacity of the rotor is therefore very easily predictable. The service life of the hydraulic camshaft adjuster is therefore precisely predictable.
Potential cost savings may be increased in particular when sintered materials are utilized for one or more of the rotor components, such as the rotor main body and/or one or more of the rotor secondary bodies.
A particularly compact multipart rotor may be created when the rotor main body and the two rotor secondary bodies are designed as mutually concentric components, and preferably have a closed, essentially circular cross section in which an approximately circular hub area is recessed. A central screw may then also engage in a known manner with the rotor, in particular the rotor main body and the two rotor secondary bodies, so that hydraulic medium channels A or B may be supplied with hydraulic medium, such as oil, from the lateral fluid outlets A and B that are present in a central screw, which acts as a central valve, in order to selectively supply working chambers A or B of a vane cell with the hydraulic medium/oil.
It is also advantageous when the rotor main body is situated in the manner of a sandwich, for example axially nested/layered/mounted between the plate-like first rotor secondary body and the plate-like second rotor secondary body, or the rotor main body, the first rotor secondary body, and the second rotor secondary body are situated relative to one another in the manner of an onion skin, for example predominantly radially nested/layered. Two- or three-part rotors having a design according to a sandwich principle or according to an onion skin principle may then be implemented. It is also possible for more than three parts to form the rotor. The individual parts are axially and radially joined together by a form-fit, force-fit, and/or integral bond connection.
When the first sleeve-like rotor hub body is inserted into a groove in the shell-like rotor main body in such a way that the first rotor secondary body adjoins or rests against the rotor main body on three sides, at least in sections, precise positioning of the individual parts relative to one another is possible, and shifting of the individual parts with respect to one another, even at high pressures, is precluded.
In the onion skin principle, axial caulking or rolling at the front side of the rotor, for example the rotor main body, may be used for interior parts.
In the sandwich principle, segment rims at one part may be connected to segment recesses in a further/adjoining/adjacent part. It is thus possible for tabs near the circumferential surfaces to engage with pockets which are diametrically opposed or which have a similar geometry, the tabs being present with interruptions or present circumferentially on the rotor main body, and engaging with an (interrupted or circumferential) pocket or multiple pockets of the first or second rotor secondary body. The tab may also be formed on the particular rotor secondary body, engaging with a corresponding pocket on the rotor main body.
The caulked connection may then be established by plastic deformation of the rims or tabs, radially inwardly and/or in the axial direction.
For a particularly precise rotor design, it is advantageous when the caulking is followed by a calibration process, i.e., calibration of the combined rotor product. This results in a reduction in porosity, in particular at the surface. The tabs, which may also be referred to as rims, have a partial cross section, and the partial cross sections are oriented in the same direction. In other words, the orientation of partial cross sections of the rims is in the same direction for multiple parts in the assembly.
The rims/tabs are deformed in the same direction in a separate/same process step via a calibration tool.
Calibration of the sintered parts is a local re-compaction of sintered pore surfaces, with the aim of compensating for distortions in the sintering process, i.e., increasing the dimensional accuracy as well as the surface density, surface hardness, surface quality of the relevant functional surfaces or functional elements, and the strength of the component.
The sintered part is re-compacted in a calibration tool similar to a pressing tool. For wall thicknesses of approximately 3 mm, the degree of pressing is usually several tenths of a millimeter (approximately 0.1-0.3 mm). The local overpressing of the sintered surfaces may thus be up to 12% maximum of the wall thickness.
Depending on the density and material of the parts, improvements in the dimensional accuracy by approximately two tolerance classes may be achieved (for example, from ISO/IT 8-9 to ISO/IT 6-7). However, for high densities and strengths of the sintered material, the achievable improvements in the dimensional accuracy are limited.
Depending on the pore density and pore size in the starting material, the compaction process (deformation in the pressing tool or rolling), and the degree of deformation, the re-compaction may be increased by up to 100% maximum of the possible spatial filling. The calibrated surfaces are thus virtually pore-free, and the material density in the surface region is essentially comparable to the density of the solid base material (for steel, for example, approximately 7.8 g/cm3).
To allow easier penetration of the rims into fairly soft material, it is advantageous when at least the rims/tabs have a higher density and/or greater hardness than the material in the area of the pocket/recess into which the rims are caulked; however, there may also be a difference in the density/hardness in such a way that the rims penetrate into fairly hard material. A reversal of the penetration principles is thus possible.
It is advantageous when the radial oversize of the wedge-like rims/tabs with respect to the rotor (nominal) diameter is 0.01 mm to 1 mm prior to the calibration. The rims may also be radially deformed to be less than the rotor diameter; i.e., the rims may be deformed radially farther inwardly than specified by the rotor (nominal) outer diameter.
Stamping may therefore be provided, the stamping preferably having a minimal width to avoid a hydraulic short circuit between channels A and B. As an alternative to or in addition to the form-fit connection, a force-fit connection may be used, for example via a longitudinal press fit or screw connection. An inner part which is concentrically situated in the rotor main body, for example a rotor secondary body such as the second rotor secondary body, may then be connected to the particular mating piece via a press fit connection, such as a thermal press fit connection, a longitudinal press fit, or a screw connection. When screws are used, it has proven to be advantageous to use at least three, four, or five screws. In one variant, the screws may be manufactured from the same sintered material as the rotor main body or one of the rotor secondary bodies.
As an alternative to or in addition to the form-fit connection and/or the force-fit connection, an integral bond connection may also be used which is effectuated by laser, resistance, or friction welding, for example. In addition, sintering in a parting line between the individual components, in particular between the rotor layers after the assembly or joining operation, is possible.
The individual parts of the assembly may be provided with different densities, hardnesses, and/or pore sizes. It is advantageous when the rotor main body or a middle part has a low density, since this part is then easier to calibrate and the costs may be reduced. The exterior parts, in particular when the sandwich principle is used, may then have a high density in order to provide more strength.
The individual parts may also be manufactured from different materials, for example sintered steel-plastic or preferably steel-sintered steel.
In the sandwich principle, the rotor main body, which is centrally situated between the two rotor secondary bodies, may be made of sintered steel to allow easy calibration and cost-effective manufacture. The rotor secondary bodies, which also function as outer parts, may be designed as stamped or shaped parts in order to provide greater strength.
One advantageous exemplary embodiment is also characterized in that the second rotor secondary body is designed as a ring, for example as a bearing ring or support ring. The second rotor secondary body comes into contact, for example front-side contact, with the camshaft during subsequent use, and may then provide sufficient strength in the event of impacts, for example. The load-bearing capacity of the rotor and thus of the hydraulic camshaft adjuster is increased.
The rotor may be further optimized with regard to weight and cost if there are differences in material and/or density and/or hardness, such as differences in surface hardness and/or differences in porosity, between one component and the two other components, or between all components of the group made up of the rotor main body, the first rotor secondary body, and/or the second rotor secondary body.
It is advantageous when the rotor main body, the first rotor secondary body, and/or the second rotor secondary body is/are made of a metallic and/or ceramic sintered material, a steel alloy, a light metal alloy, or a plastic. Mixtures of these materials are also possible. Designing the rotor to withstand load is thus facilitated.
Assembly is facilitated when the caulking is achieved by the engagement of a tab, which may also be referred to as a rim, of a first component with a pocket or recess in a second component, the contour of the pocket or recess being adapted to the contour of the tab or differing from same.
For component strength, it is advantageous when an angle α is defined between a surface extending in the circumferential direction and a surface, oriented in the radial direction, of the pocket in a radially inner area of the pocket, in which α=90°, or 90°<α<100°, or α<90°. A particularly good specific embodiment may be achieved in particular when α<90°, for example is in a range of 80° to 89°.
One advantageous exemplary embodiment is also characterized in that the tab in the caulked state is in flush alignment with an outer circumferential surface, for example of the rotor main body and/or one or both rotor secondary bodies, which extends in the axial direction and radially outwardly delimits the pocket. It is advantageous when the tab is leveled, without cutting, by a calibration tool in such a way that the surface of the component which forms the tab is different from its interior with regard to the density, and has lower porosity/porosities.
One advantageous exemplary embodiment is also characterized in that multiple hydraulic medium-conducting channels are provided, for example as oil channels, for filling working chambers A and B with oil.
It is also advantageous when all hydraulic medium-conducting channels extend, at least in sections, in a shared plane, for example a reference plane oriented perpendicularly with respect to the axial direction, or when the hydraulic medium-conducting channels connected to one working chamber extend in the first reference plane, and the hydraulic medium-conducting channels connected to the other working chamber extend in a second reference plane in parallel to and situated at an axial distance from the first reference plane. In the present patent application, the reference planes are understood to mean transverse planes, and do not extend along a center axis, and include the center axis only at certain points, namely, where the center axis of the rotor perpendicularly intersects the reference plane.
The second rotor secondary body, designed as a ring and situated within the first rotor secondary body and the rotor main body, may have a hydraulic medium-conducting contour, preferably only on one side, for example in the manner of a bulging, curved, or concave indentation, in order to supply hydraulic medium such as oil in a particularly efficient and targeted manner to the particular hydraulic medium-conducting channel, and thus, to the particular working chamber A or B.
The present invention is explained in greater detail below with the aid of the drawings, which illustrate various exemplary embodiments and variants.
The figures are merely schematic, and are used only for an understanding of the present invention. Identical elements are provided with the same reference numerals. Features of the individual exemplary embodiments may also be implemented in other exemplary embodiments, i.e., are interchangeable.
Rotor 1 from
A hydraulic medium-conducting channel 5 which may supply working chamber B with oil is formed in the manner of an oil channel in the first separating plane. This hydraulic medium-conducting channel 5 is referred to as channel B.
A hydraulic medium-conducting channel 5 is likewise formed in the other separating plane, between rotor main body 2 and second rotor secondary body 4. This hydraulic medium-conducting channel is referred to as channel A, since it fills working chamber A. Working chambers A and B, which are delimited by a radially inwardly protruding projection of a stator (not illustrated), together define a vane cell which is present between two vanes 6. Grooves 7 are provided at the radial ends of vanes 6, into which sealing elements, such as sealing lips, are insertable.
It is clearly apparent in
However, as is clearly apparent in
In the onion skin principle, rotor main body 2 may also be referred to as a rotor shell, into which first rotor hub body 3, which may also be referred to as an inner rotor sleeve, is concentrically inserted, the second rotor secondary body, acting as a support ring or bearing ring, being concentrically inserted into rotor main body 2 and also into first rotor secondary body 3. All three components are situated concentrically with respect to one another, and have a circular recess for accommodating a central valve or some other cylindrical component, such as a camshaft. However, the front side of the camshaft is supported on second rotor secondary body 4, for which reason second rotor secondary body 4 is made of a steel alloy.
As is apparent in
In turn, caulking 10 is used in
In particular, the geometry variants illustrated in
Thus, the component which forms pocket 12 has an angle α which may be 90°, or which may be between 90° and 100°, or which may be less than 90°. In particular the variant in which α is less than 90° is preferred. To ensure the radial protrusion of tab/rim 11, an angle β may be provided which may be between 60° and 88°. Values of 10° to 60°, in particular 30°, 33°, 40°, 45°, and 57°, are also conceivable.
The caulked approach is apparent in the detail in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 226 466.6 | Dec 2013 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2014/200583 | 10/22/2014 | WO | 00 |
