CONTROL VALVE FOR A CAMSHAFT ADJUSTER

Abstract

A control valve for a camshaft adjuster for an engine is provided. The control valve includes a valve sleeve having one or more inlet openings, two supply openings, and an outlet opening, and a control piston guided in the valve sleeve. The piston, together with the valve sleeve and control edges arranged on the control piston, form three annular ducts. A fluid-conducting connection between an inlet opening and a supply opening can be controlled via a first annular channel. A fluid-conducting connection between the inlet opening and another supply opening can be controlled via a second annular channel. The first annular channel and the second annular channels may enclose a central annular channel, via which a fluid-conducting connection between the supply opening and the outlet opening, as well as between the another supply opening and the outlet opening, can be controlled.

Claims

1. A control valve for a camshaft adjuster including a valve sleeve having one or more inlet openings, two supply openings and an outlet opening and a control piston guided in the valve sleeve, wherein the piston together with the valve sleeve and control edges arranged on the control piston, forms three annular ducts, wherein a first fluid-conducting connection between an inlet opening and a first supply opening can be controlled via a first annular channel, and a second fluid-conducting connection between the inlet opening or a further inlet opening axially spaced from the inlet opening, and a second supply opening can be controlled via a second annular channel, wherein the first annular channel and the second annular channel enclose a central annular channel, via which a fluid-conducting connection between the supply opening and the outlet opening, as well as between the supply opening and the outlet opening, can be controlled.

2. The control valve according to claim 1, wherein the control piston comprises a piston cavity, wherein the central annular channel can be directly connected with the outlet opening, the annular channel can be directly connected with the supply opening, and the annular channel can be directly connected with the supply opening, wherein one of the annular channels can be directly connected with the inlet opening, and wherein the other one of the annular channels can be indirectly connected via the piston cavity with the inlet opening.

3. The control valve according to claim 2, wherein the indirect connection is carried out via an annular supply channel formed in the piston cavity, which annular supply channel is directly connected with the annular channel and the annular channel, via the piston opening and the piston opening.

4. The control valve according to claim 3, wherein the annular supply channel is formed between an inside surface of the control piston and an outside surface of a tubular piston insert.

5. The control valve according to claim 4, wherein the piston insert seals the annular supply channel toward a surrounding area, wherein a space formed between valve sleeve and control piston is connected via a channel formed in the piston insert with the surrounding area.

6. The control valve according to claim 1, wherein the valve sleeve is designed in the form of a central screw.

7. The control valve according to claim 1, wherein the valve sleeve has a plastic injection molding.

8. The control valve according to claim 7, wherein the valve sleeve is arranged in a central screw.

9. The control valve according to claim 8, wherein the inlet opening is connected via an axial channel formed in the plastic injection molding with an inlet connection formed on the central screw.

10. (canceled)

11. A camshaft adjuster comprising: a valve housing extending along an axis and defining a valve inlet opening at one axial end thereof, a first housing supply opening, a second housing supply opening, and a housing outlet opening; a valve sleeve within the valve housing having a sleeve inlet opening, a first sleeve supply opening, a second sleeve supply opening, and a sleeve outlet opening; and a control piston slideable along the axis within the valve sleeve and guided by the valve sleeve, wherein the piston is slideable from a first axial position to a second axial position relative to the valve sleeve and valve housing, wherein the piston and the valve sleeve combine to form a first annular duct, a second annular duct, and a third annular duct; wherein when the control piston is slid from the first axial position to the second axial position: a first fluid connection is made between the housing inlet opening, the sleeve inlet opening, the first housing supply opening, the first sleeve supply opening, and the first annular duct, and a second fluid connection is made between the second housing supply opening, the second sleeve supply opening, the third annular duct, the sleeve outlet opening, and housing outlet opening.

12. The camshaft adjuster of claim 11, wherein the second housing supply opening and the housing outlet opening are on opposite axially sides of the first housing supply opening.

13. The camshaft adjuster of claim 11, wherein the valve sleeve is a screw with a hollow interior.

14. The camshaft adjuster of claim 13, wherein the valve sleeve is a plastic injection-molded screw.

15. The camshaft adjuster of claim 11, wherein when the control piston is slid from the second axial position to the first axial position, the valve sleeve covers the first annular duct to disconnect the first fluid connection.

16. The camshaft adjuster of claim 11, wherein the control piston includes a plurality of protrusions extending radially outward and engaging an inner surface of the sleeve to at least partially define the annular ducts.

17. The camshaft adjuster of claim 16, wherein the plurality of protrusions includes a protrusion that passes along the first sleeve supply opening when the control pistons is slid from the first axial position to the second axial position to fluidly couple the first sleeve supply opening to the first annular duct.

18. The camshaft adjuster of claim 16, wherein the plurality of protrusions includes a protrusion that passes along the second sleeve supply opening when the control piston is slid from the first axial position to the second axial position to fluidly couple the second sleeve supply opening to the third annular duct.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various embodiments are now described in more detail with reference to the drawings. Functionally equivalent elements of the embodiments described are marked with the same reference signs.

[0021] FIG. 1 shows a longitudinal section of the control valve of the embodiment depicted;

[0022] FIG. 2 shows the control valve depicted in FIG. 1 in a second switching position;

[0023] FIG. 3 shows in an exemplary manner a camshaft adjuster having a volume accumulator and the control valve depicted in FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 shows a longitudinal section of an exemplary embodiment of a control valve 1. The control valve comprises a central screw as valve housing 3 and a hollow cylindrical control piston 4, which can be axially moved in a respective hollow space of the valve housing 3. The adjustment range of the control piston 4 is axially limited by a retaining ring 5 at the first end 6 and a closing element 7 at the second end 8. The valve housing 3 can be received by a hollow space of a camshaft and be used for controlling a camshaft adjuster (see FIG. 4). Together with an outer thread 10, a flange 9 serves the purpose of connecting the control valve 1 and the camshaft. On its outer circumference, the valve housing 3 has three connections: the connections form the supply port A, the further supply port B and the outlet connection C. An inlet connection P is located at the second end 8 of the valve housing. A filter 12 and a check valve 2 are arranged around the opening, which forms the inlet connection P.

[0025] The control piston 3 is guided inside a valve sleeve 13. The valve sleeve 13 comprises an internal component 14 and an external component 15. The internal component 14 is produced from a metallic material and is surrounded by an external plastic component. 15. Both components are designed in the form of a sleeve or hollow cylinder. The external sleeve-shaped component 15 is produced as an injection-molded part and the internal sleeve-shaped components 14 as an insert, which is overmolded during the injection molding process of the external component.

[0026] On its outside surface, the control piston 4 has four sections with expanded diameter, which include three sections with a reduced diameter. Together with the inside surface of the pressure medium guide insert 13, said sections form an annular channel A 16, an annular channel B 17 and a central annular channel 18. To control a camshaft adjuster, the control piston 4 can assume two switching positions, which are marked by the actual course of possible pressure medium paths.

[0027] A switching position is implemented via a setting device (not shown), which usually involves an electromagnetic actuator. A push rod connected to an anchor of the electric magnet is brought in contact with an actuation surface at the front end of the control piston 4. As a result, the force exerted on the anchor is transferred via the push rod to the control piston 4, thus causing an axial movement against the force of a spring 19: the annular channel A 16 can be moved into the axial position of the supply opening A 20. Therefore, the annular channel B 17 can be brought into the axial positions of the supply opening B 21 and the inlet opening P 22. The central annular channel 18 can be brought into the axial positions of the supply opening A 20 and the supply opening B 21.

[0028] In this way, the first switching position shown in FIG. 1 can be set. The setting device is not energized, which leaves the control piston 4 in a non-actuated position. In the first switching position, a pressure medium path is achieved between the inlet connection P and the supply port B. An additional pressure medium path is produced between the supply port A and the output connection C.

[0029] FIG. 3 shows the control valve in its second switching position. The setting device is energized and therefore the control piston is in an actuated position. In the second switching position, a pressure medium path 4 is produced between the supply port B and the outlet connection C. A further pressure medium path is produced between the inlet connection B and the supply port A: the pressure medium flows via the inlet connection P into the control valve 1 and flows along an axial channel 23 in the inlet opening P, which is overmolded with plastic, into the inlet opening P. From there, the pressure medium path runs via the piston opening B 24 into the annular supply channel 26 formed via a piston insert 25 in the piston cavity. The piston opening A 27, which adjoins the annular supply channel 26, opens the way into the annular channel A 16, and which in the second switching position a connection is available to the supply opening A 20 and to the supply port A.

[0030] Therefore, the annular supply channel 26 is formed between the inside surface of the control piston 4 and the outside surface of a tubular piston insert 25. In this way, it is possible to produce an indirect connection via an annular supply channel 26 formed in the piston cavity 28. The annular supply channel 26 is directly connected via the piston openings A and B 27, 24 with the annular channel A 16 and the annular channel B 17. In addition, the piston insert 27 basically seals the annular supply channel 26 toward the surrounding area, wherein a space 28 formed between valve sleeve and control piston is connected with the surrounding area via a channel 29 formed in the piston insert 27.

[0031] FIG. 3 shows a hydraulic camshaft adjuster 30 having a stator 31 and a rotor 32. It displays two pressure chambers 34 enclosed by stator and rotor and separated from one another by chamber walls 33. Via a wing 35, said pressure chambers 34 are respectively divided into two working chambers A and B, or 36, 37, which are hydraulically working against each other. The hydraulic camshaft adjuster also has a volume accumulator 38. In the center, a receptacle 39 for a control valve of the embodiment described above is arranged. Each of the working chambers A 36 can be brought into fluid-conducting connection with supply port A, and each of the working chambers B 37 can be brought in fluid-conducting connection with the supply port B 29. The volume accumulator 38 can be brought in fluid-conducting connection with the output connection C.

[0032] In addition, the volume accumulator 38 can be brought in fluid-conducting connection with the working chamber A 36 and the working chamber B 37. For this purpose, hydraulic channels are located in the camber walls 33 of the stator. Check valves are used to prevent pressure medium from flowing from one of the working chambers 36, 37 to the volume accumulator. The volume accumulator 38 also has an outlet, which has the purpose of supplying hydraulic fluid to a reservoir (tank).

LIST OF REFERENCE SIGNS

[0033] 1 control valve [0034] 2 check valve [0035] 3 central screw, valve housing [0036] 4 control piston [0037] 5 retaining ring [0038] 6 first end [0039] 7 closing element [0040] 8 second end [0041] 9 flange [0042] 10 outer thread [0043] 11 outlet opening C [0044] 12 filter [0045] 13 valve sleeve [0046] 14 internal component [0047] 15 external component, plastic injection molding [0048] 16 annular channel A [0049] 17 annular channel B [0050] 18 central annular channel [0051] 19 spring [0052] 20 supply opening A [0053] 21 supply opening B [0054] 22 inlet opening P [0055] 23 axial channel [0056] 24 piston opening B [0057] 25 piston insert [0058] 26 annular supply channel [0059] 27 piston opening A [0060] 28 space formed between valve sleeve and control piston [0061] 29 channel [0062] 30 camshaft adjuster [0063] 31 stator [0064] 32 rotor [0065] 33 chamber wall [0066] 34 pressure chamber [0067] 35 wing [0068] 36 working chamber A [0069] 37 working chamber B [0070] 38 volume accumulator [0071] 39 receptacle [0072] 40 check valve [0073] 41 piston cavity [0074] A supply port A [0075] B supply port B [0076] P inlet connection P [0077] C outlet connection C [0078] T outlet connection T