Abstract
A hydraulic camshaft adjuster has a stator, a rotor arranged movably with respect to the stator, and a central valve via which oil supply of working chambers of the hydraulic camshaft adjuster is controlled. A deformable sealing sleeve is arranged between the central valve and the rotor. The sealing sleeve has an initial length in an axial direction, and after assembly, has a deformation such that the length of the sealing sleeve changes from the initial length to an assembled length. The sealing sleeve bears at least partially in the radial direction against the central valve and against the rotor.
Claims
1. A hydraulic camshaft adjuster comprising: a stator; a rotor that can move in relation to the stator; a central valve configured to control oil supply to working chambers of the hydraulic camshaft adjuster; and a deformable sealing sleeve between the central valve and the rotor, wherein the sealing sleeve has an initial axial length when it is not subjected to forces, and is deformed after assembly such that the length of the sealing sleeve changes from the initial axial length to an assembled length, wherein the sealing sleeve bears radially, at least in sections, on the central valve and on the rotor, wherein a skin surface of the sealing sleeve forms a bellows; wherein the sealing sleeve has a plurality of openings on its skin surface for supplying hydraulic fluid to from the central valve to the working chambers, wherein the bellows includes ridges on the skin surface, and wherein at least one of the plurality of openings is located entirely on at least one of the ridges to facilitate flow of the hydraulic fluid from the central valve to the working chambers through the at least one of the ridges.
2. The hydraulic camshaft adjuster according to claim 1, wherein the sealing sleeve has a contour that deviates from a cylindrical shape.
3. The hydraulic camshaft adjuster according to claim 1, wherein the sealing sleeve has a first section with a first diameter, and at least one second section with a second diameter which is greater than the first diameter.
4. The hydraulic camshaft adjuster according to claim 1, wherein the ridges project in semicircles or ramps over a cylindrical body of the sealing sleeve.
5. The hydraulic camshaft adjuster of claim 1, wherein the initial length is less than the assembled length.
6. The hydraulic camshaft adjuster of claim 1, wherein the initial length is greater than the assembled length.
7. The hydraulic camshaft adjuster according to claim 1, wherein the ridges are semi-circular in shape.
8. A method of producing a hydraulic camshaft adjuster having a stator, a rotor moveable relative to the stator, and a central valve configured to control oil supply to working chambers of the hydraulic camshaft adjuster, comprising: providing a deformable sealing sleeve with a skin surface having a bellows and a plurality of openings on the skin surface for supplying hydraulic fluid to the working chambers, wherein the bellows includes ridges on the skin surface configured to seal against the rotor, and wherein at least one of the plurality of openings is located entirely on one of the ridges, to deliver the hydraulic fluid from an inner side of the sealing sleeve to an outer side of the sealing sleeve via the plurality of openings; and assembling the deformable sealing sleeve radially between the central valve and the rotor, wherein the assembling includes axially compressing the sealing sleeve from a pre-assembled length to an assembled length that is less than the pre-assembled length.
9. The method of claim 8, wherein the axially compressing causes radial expansion of the bellows.
10. The method of claim 8, wherein the step of providing includes forming the sealing sleeve to have the ridges on the skin surface which project in semicircles or ramps over a cylindrical body of the sealing sleeve.
11. A hydraulic camshaft adjuster comprising: a stator; a rotor that can move in relation to the stator; a central valve configured to control oil supply to working chambers of the hydraulic camshaft adjuster; and a deformable sealing sleeve assembled radially between the central valve and the rotor, the sealing sleeve having an axial end contacting the central valve, wherein the central valve supplies a compression force on the axial end of the sealing sleeve causing axial compression of the sealing sleeve such that the sealing sleeve has a first length when the sealing sleeve is not assembled to the central valve and a second length that is less than the first length when assembled; wherein the sealing sleeve have bellows including ridges formed thereon, wherein the ridges have openings formed therethrough, wherein at least one of the openings is located entirely on one of the ridges, and wherein the ridges are configured to seal against the rotor and also deliver fluid from an inner side of the sealing sleeve to an outer side of the sealing sleeve via the openings.
12. The hydraulic camshaft adjuster of claim 11, wherein the bellows is radially expanded based on the compression force supplied to the axial end of the sealing sleeve.
13. The hydraulic camshaft adjuster of claim 11, wherein the ridges are semi-circular in shape.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The disclosure shall be explained in greater detail below based on embodiments, with reference to the attached drawings. Identical components or components that have the same function are indicated by the same reference symbols in the drawings. Therein:
(2) FIG. 1 shows a hydraulic camshaft adjuster according to an embodiment, which has a sealing sleeve between the central valve and the rotor;
(3) FIG. 2 shows a section through a sealing sleeve in the unloaded state, and when deformed by an assembly force;
(4) FIG. 3 shows another sectional view of a sealing sleeve;
(5) FIG. 4 shows a three dimensional illustration of a sealing sleeve, which is inserted between the rotor and the central valve;
(6) FIG. 5 Another exemplary embodiment of a sealing sleeve in a three dimensional illustration and in a sectional view; and
(7) FIG. 6 shows a schematic illustration of the deformation and change in length of the sealing sleeve during assembly.
DETAILED DESCRIPTION OF THE DRAWINGS
(8) A hydraulic camshaft adjuster 1 for adjusting the control times of the valves in an internal combustion engine is shown in FIG. 1. The hydraulic camshaft adjuster 1 has a stator 2 and a rotor 3. The rotor 3 and the stator 2 are arranged concentric to one another about a common central axis 17. The rotor 3 has a central opening in which a central valve 4 for the hydraulic control of the working chambers 6, 7 of the hydraulic camshaft adjuster 1 is located. Channels for supplying or discharging hydraulic fluid to or from the working chambers 6, 7 are formed in the stator 2 and/or the rotor 3. A gap 16 is formed between the rotor 3 and the central valve 4, into which a sealing sleeve 5 is inserted. The sealing sleeve 5 can be either inserted into the gap 16 with a certain amount of play, or it can be pressed into the opening in the rotor 3, or stretched onto the outer diameter of the central valve 4. It can be seen from the illustration in FIG. 1 that the clamping length L.sub.KR of the rotor 3 is shorter than the axial length L.sub.0 of the sealing sleeve 5 in the unassembled state prior to installing the hydraulic camshaft adjuster 1 on a camshaft, not shown, when it is not subjected to forces, by a length of ΔL. Because of the geometry of the sealing sleeve 5, an axial compression of the sealing sleeve 5 results in a radial expansion of the sealing sleeve 5. The central opening 15 in the rotor 3 can be in the form of a cylindrical bore hole, and requires no ledges in order to form channels for conducting oil, because these are formed by the first sections 9 of the sealing sleeve 5 between the sealing sleeve 5 and the rotor 3, and separated by the respective second sections 10 of the sealing sleeve 5.
(9) The sealing sleeve 5 is shown in FIG. 2 in a sectional view in the unloaded initial state and after assembly of the hydraulic cam shaft adjuster 1. The geometry of the sealing sleeve 5 is selected such that an axial compression of the sealing sleeve 5 from an initial length L.sub.0 to a length L.sub.1 by the length ΔL causes a radial expansion of the sleeve from X.sub.0 to X.sub.1. The precise relationship between the length change ΔL and the expansion ΔX can be determined by the geometry of the sealing sleeve 5. If ΔX is at least as much as the gap 16, the sealing sleeve 5 forms a seal between the rotor 3 and the central valve 4. Even if the expansion of the sealing sleeve 5 ΔX is smaller than the gap 16, the seal is improved over prior designs as long as X.sub.1 is smaller than the previously possible radial play between the central valve 4 and the rotor 3. The sealing sleeve 5 forms a seal between the central valve 4 and the rotor 3. The sealing sleeve 5 also serves as a sleeve for distributing oil into the working chambers 6, 7 of the hydraulic camshaft adjuster 1. For this, the sealing sleeve 5 has a first diameter D.sub.1 at a first section 9, Which may be the smallest diameter of the sealing sleeve 5, allowing the sealing sleeve to be slid onto the central valve 5. Starting from this first diameter D.sub.1, the sealing sleeve 5 has at least one second section 10 that has a larger diameter D.sub.2, wherein the second sections 10 each form bearing surfaces of the sealing sleeve 5 on the rotor 3. There are numerous openings 11 formed on a skin surface 8 of the sealing sleeve 5 that enable a hydraulic control medium of the hydraulic camshaft adjuster 1 to flow through the sealing sleeve 5 from the central valve 4 into the working chambers 6, 7 of the hydraulic camshaft adjuster 1. Starting from a cylindrical body 14, the sealing sleeve 5 has numerous ridges 13 that may extend radially in semicircles or ramps over the cylindrical body 14. Numerous ridges 13 can adjoin one another in the manner of a bellows 12 such that the sealing sleeve 5 can be deformed particularly easily in this region, and potentially form numerous successive sealing edge(s). In order to enable a particularly simple deformation in the region of the ridges 13, the material of sealing sleeve 5 where the ridges 13 are located can be thinner than that of the cylindrical body 14. The thickness of the material may be substantially constant, however, over the entire length of the sealing sleeve 5, in order to keep the production costs for the sealing sleeve 5 as low as possible. Differences in the diameters due to production conditions, coaxial tolerances and misalignments between the central valve 4 and the rotor 3, can be compensated for by the radial expansion of the sealing sleeve 5 by the value X.sub.1 and the elastic design of the sealing sleeve 5. Furthermore, the geometry of the rotor 3 in the region of the central opening 15 is simplified, because the inner diameter of the rotor 3 in which the central valve 4 is accommodated no longer needs ledges. The inner geometry of the rotor 3 can form a cylindrical surface. Furthermore, there is no longer need for a grinding of the outer diameter of the central valve 4, which had been necessary with the design known from the prior art in order to stay within the stipulations for tolerances and the leakage.
(10) Another illustration of a sealing sleeve 5 is shown in FIG. 3. It can be seen therein that the openings 11 are each formed in just one side 18 of the respective ridges 13, such that the crest of the respective ridge 13 forms a seal with the rotor 3, which hydraulically separates the individual oil supply channels from one another. FIG. 4 shows a three dimensional illustration of such a sealing sleeve 5, which has numerous ridges that hydraulically separate the channels conducting oil from the central valve 4 to the working chambers 6, 7.
(11) Alternatively, the sealing sleeve 5 can also be expanded axially by a radial compression. For this, the sealing sleeve shown in FIG. 5 and FIG. 6 is produced such that it has an axial length L.sub.0 in the uninstalled state, when it is not subjected to forces, which is axially shorter than the clamping length L.sub.KR of the rotor 3 by ΔL. The radial dimension X.sub.1 of the sealing sleeve 5 in the initial state is greater than the gap 16 between the central valve 4 and the rotor 3. When the sealing sleeve 5 is inserted into the central opening 15 in the rotor 3, and the central valve 4 is installed, the sealing sleeve 5 is compressed radially from the initial height X.sub.1 to the width of the gap 16, i.e. the height X.sub.0. This assembly process and the associated deformation of the sealing sleeve 5 is illustrated schematically in FIG. 6. For the sealing sleeve 5 to be able to be installed, an unobstructed axial expansion of the sealing sleeve 5 must be possible for this radial compression. The sealing sleeve 5 can only be lengthened axially by ΔL, such that in the assembled state, the sealing sleeve can only be lengthened to the clamping length L.sub.KR of the rotor 3. Such a sealing sleeve is shown in FIG. 5.
(12) FIG. 5 shows that it makes sense or the design of the sealing sleeve 5 to have ramp-shaped or semicircular ridges 13 that project over the cylindrical body 14 of the sealing sleeve 5, which flatten out during the assembly, resulting in an axial expansion of the sealing sleeve 5. Each of the ridges 13 has a first and second side 18, which may be symmetrical to one another, reflected over the crest of the ridge 13. When a sealing sleeve 5 shown in FIG. 5 is inserted into the hydraulic camshaft adjuster 1 and tensioned with the central screw 4, it can be seen that oil conducting channels are formed between each of the ridges 13, by means of which the pressure chambers 6, 7 can be supplied with hydraulic fluid from the central valve 4. The number of ridges 13 may be different than that is shown in FIGS. 2-5, and is determined by the respective hydraulic design of the hydraulic camshaft adjuster 1.
REFERENCE LIST
(13) 1 camshaft adjuster 2 stator 3 rotor 4 central valve 5 sealing sleeve 6 first working chamber 7 second working chamber 8 skin surface 9 first section 10 second section 11 opening 12 bellows 13 ridge 14 basic structure body 15 opening 16 gap 17 central axis 18 sides ΔL change in length caused by deformation L.sub.0 length of the sealing sleeve in the initial state L.sub.1 length of the sealing sleeve in the deformed state L.sub.KR clamping length of the rotor ΔX change in the radial height caused by the deformation X.sub.0 radial height of the sealing sleeve in the initial state X.sub.1 radial height of the sealing sleeve in the deformed state
