HYDRAULIC VALVE FOR A CAM PHASER

Abstract

A hydraulic valve, in particular for a phaser of a cam shaft, the hydraulic valve including a bushing including a piston that is displaceable in a bore hole along a longitudinal direction; a supply connection configured to supply a hydraulic fluid; at least a first operating connection and a second operating connection; and at least one tank drain configured to drain the hydraulic fluid, wherein the first operating connection and the second operating connection are alternatively connectable with each other and/or with the supply connection and/or with the at least one tank drain through at least one check valve by displacing the piston.

Claims

1. A hydraulic valve for a phaser of a cam shaft, the hydraulic valve comprising: a bushing including a piston that is displaceable in a bore hole along a longitudinal direction; a supply connection configured to supply a hydraulic fluid; at least a first operating connection and a second operating connection; and at least one tank drain configured to drain the hydraulic fluid, wherein the first operating connection and the second operating connection are alternatively connectable with each other or with the supply connection or with the at least one tank drain through at least one check valve by displacing the piston, wherein the at least one check valve is arranged in an inner portion of the piston, wherein the at least one check valve includes a band shaped flexible element and releases a connection between an outside of the piston and the inner portion of the piston in an open position of the at least one check valve, and wherein an inside of the piston includes an outer stop for the at least one check valve so that the band shaped flexible element is openable in an inward direction by a hydraulic pressure provided at the outside of the piston.

2. The hydraulic valve according to claim 1, wherein a first check valve of the at least one check valve is associated with the first operating connection and a second check valve of the at least one check valve is associated with the second operating connection, and wherein the first check valve and the second check valve are arranged in the inner portion of the piston.

3. The hydraulic valve according to claim 2, wherein a first operating position of the hydraulic valve is provided in which a first fluid path of the hydraulic fluid from the first operating connection through the first check valve associated with the first operating connection to the second operating connection is open, and wherein a second operating position is provided in which a second fluid path of the hydraulic fluid from the second operating connection through the second check valve associated with the second operating connection to the first operating connection is open.

4. The hydraulic valve according to claim 1, wherein a center position of the hydraulic valve is provided in which center position the first operating connection and the second operating connection are closed independently from the at least one check valve.

5. The hydraulic valve according to claim 1, wherein an additional fluid path of the hydraulic fluid is provided from the outside of the piston to the at least one check valve through bore holes in the piston.

6. The hydraulic valve according to claim 5, wherein a radial control groove at least partially extending on the outside of the piston is provided for supplying the bore holes with the hydraulic fluid.

7. The hydraulic valve according to claim 5, wherein the outside of the piston is respectively configured as a flat surface in a portion of the bore holes.

8. The hydraulic valve according to claim 1, wherein the band shaped flexible element is secured against a displacement in the longitudinal direction by a fixation element axially enveloping the band shaped flexible element.

9. The hydraulic valve according to claim 8, wherein the at least one check valve is configured with at least one sleeve as an integrated unit, wherein the integrated unit includes the band shaped flexible element and the fixation element, and wherein the band shaped flexible element contacts an inside of the sleeve with a preload.

10. The hydraulic valve according to claim 1, wherein the band shaped flexible element is arranged in a bore hole of the piston and secured against a displacement in the longitudinal direction by at least one annular fixation element.

11. The hydraulic valve according to claim 8, wherein the fixation element is configured cylindrical or hollow cylindrical and includes two axially offset portions with radially extending protrusions, and wherein the band shaped flexible element is arranged about the fixation element and between the two axially offset portions and is axially fixated on the fixation element by the protrusions.

12. The hydraulic valve according to one claim 8, wherein the fixation element forms a stop for the band shaped flexible element in the inward direction.

13. The hydraulic valve according to claim 9, wherein the radially extending protrusions are provided for supporting the at least one sleeve.

14. The hydraulic valve according to claim 1, wherein an additional check valve with a band shaped flexible element is provided at the supply connection within the piston, and wherein the additional check valve is openable in the inward direction by a hydraulic pressure provided at the supply connection.

15. A phaser for a cam shaft, the phaser comprising the hydraulic valve according to claim 1, wherein the first operating connection is connected with the first pressure chamber of the phaser and the second operating connection is connected with the second pressure chamber of the phaser, wherein the first operating connection and the second operating connection are alternatively connectable with each other or with the supply connection or with the at least one tank drain through at least one check valve by displacing the piston, wherein the at least one check valve is arranged in an inner portion of the piston, wherein the at least one check valve includes a band shaped flexible element and releases a connection between an outside of the piston and an inner portion of the piston in an open position of the at least one check valve, and wherein an inside of the piston includes an outer stop for the at least one check valve so that the band shaped flexible element is openable in an inward direction by a hydraulic pressure provided at the outside of the piston.

16. A hydraulic valve for a phaser of a cam shaft, the hydraulic valve comprising: a bushing including a piston that is displaceable in a bore hole along a longitudinal direction; a supply connection configured to supply a hydraulic fluid; at least a first operating connection and a second operating connection; and at least one tank drain configured to drain the hydraulic fluid, wherein the first operating connection and the second operating connection are alternatively connectable with each other and with the supply connection and with the at least one tank drain through at least one check valve by displacing the piston, wherein the at least one check valve is arranged in an inner portion of the piston, wherein the at least one check valve includes a band shaped flexible element and releases a connection between an outside of the piston and the inner portion of the piston in an open position of the at least one check valve, and wherein an inside of the piston includes an outer stop for the at least one check valve so that the band shaped flexible element is openable in an inward direction by a hydraulic pressure provided at the outside of the piston.

17. A phaser for a cam shaft, the phaser comprising the hydraulic valve according to claim 16, wherein the first operating connection is connected with the first pressure chamber of the phaser and the second operating connection is connected with the second pressure chamber of the phaser, wherein the first operating connection and the second operating connection are alternatively connectable with each other and with the supply connection and with the at least one tank drain through at least one check valve by displacing the piston, wherein the at least one check valve is arranged in an inner portion of the piston, wherein the at least one check valve includes a band shaped flexible element and releases a connection between an outside of the piston and an inner portion of the piston in an open position of the at least one check valve, and wherein an inside of the piston includes an outer stop for the at least one check valve so that the band shaped flexible element is openable in an inward direction by a hydraulic pressure provided at the outside of the piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Further advantages can be derived from the subsequent drawing description. The drawings illustrate embodiments of the invention. The drawings, the description and the claims include several features in combination. A person skilled in the art will advantageously view the features individually and combine them into additional useful combinations, wherein:

[0033] FIG. 1 illustrates a hydraulic valve for adjusting a cam phaser according to an embodiment of the invention in a first operating position in a longitudinal sectional view;

[0034] FIG. 2 illustrates the hydraulic valve according to FIG. 1 in a center position;

[0035] FIG. 3 illustrates the hydraulic valve according to FIG. 1 in a second operating position;

[0036] FIG. 4 illustrates the check valve according to an embodiment of the invention in a closed position in a longitudinal sectional view;

[0037] FIG. 5 illustrates the check valve according to FIG. 4 in an exploded view;

[0038] FIG. 6 illustrates the check valve according to FIG. 4 in an open position depicted in a longitudinal sectional view;

[0039] FIG. 7 illustrates the hydraulic valve according to another embodiment of the invention in a longitudinal sectional view;

[0040] FIG. 8 illustrates the hydraulic valve according to another embodiment of the invention in a longitudinal sectional view;

[0041] FIG. 9 illustrates a piston of a hydraulic valve according to an embodiment of the invention in an isometric view;

[0042] FIG. 10 illustrates a piston of a hydraulic valve according to another embodiment of the invention in an isometric view; and

[0043] FIG. 11 illustrates a cam phaser according to an embodiment of the invention in a cross sectional view.

DETAILED DESCRIPTION OF THE INVENTION

[0044] In the figures identical or like components are designated with identical reference numerals. The figures only illustrate exemplary embodiments and do not limit the scope and spirit of the invention.

[0045] FIG. 1 illustrates a hydraulic valve 12 for adjusting a cam phaser 14 according to an embodiment of the invention in a first operating position 54 in a longitudinal sectional view. The hydraulic valve 12 includes a bushing 15 with a piston 44 that is arranged in a bore hole 42 so that it is moveable in a longitudinal direction L. The piston 44 is supported at the bushing 15 by a compression coil spring 24.

[0046] The bushing 15 includes a supply connection 30 for feeding a hydraulic fluid, a first operating connection 34, a second operating connection 36, and two tank drains 38, 40 for draining the hydraulic fluid. The first operating connection 34 and the second operating connection 36 are alternatively connectable with one another and/or with the supply connection 30 and/or with the at least one tank drain 38, 40 through at least one check valve 46, 48 by moving the piston 44. The two check valves 46, 48 are arranged in an inner portion 64 of the piston 44. The check valves 46, 48 include a band shaped flexible element 80 which releases a connection between the outside 66 of the piston 44 and its inner portion 64 in an open position. The inside 65 of the piston 44 includes an outer stop for the check valves 46, 48 so that the element 80 is openable towards an inside by a hydraulic pressure provided at an outside 66 of the piston 44, in particular a pulsating hydraulic pressure. A respective check valve 46, 48 is associated with the first operating connection 34 and the second operating connection 36 in the inner portion 64 of the piston 44. At the supply connection 30 another check valve 32 with a band shaped flexible element 94 is provided within the piston 44. Also this check valve 32 is openable in inward direction by a hydraulic pressure provided at the supply connection 30. The band shaped flexible element 94 contacts an inner wall 20 of the bushing 15 when this check valve 32 is without pressure in a closed condition of the check valve 32.

[0047] The check valve 46, 48 includes a fixation element 82 which is configured as a hollow cylinder with laterally extending protrusions 92. The band shaped flexible element 80 is axially fixated between the protrusions 92 and can only move in a radial direction. Two sleeves 84 envelop the fixation element 82 from both ends and are supported by the protrusions 92, wherein the band shaped flexible element 80 is preloaded and partially contacts an inside 88 of the sleeve 84 and thus closes the check valve 46, 48 in a condition without pressure. Thus, the check valve 46, 48 is configured as a preassembled integrated unit 86 which can be advantageously mounted in the inner portion 64 of the piston 44 in its entirety.

[0048] In FIG. 1 the hydraulic valve 12 is illustrated in a first operating position 54 in which a first fluid path 52 of the hydraulic fluid from the first operating connection 34 through the hydraulic valve 46 associated with the first operating connection 34 to the second operating connection 36 is open. The check valve 46 can be opened by the hydraulic pressure provided at the first operating connection 34. In the drawing of FIG. 1 the check valve 46 itself, however, is illustrated in the closed condition with the contacting band shaped flexible element 80. Also the fluid path 74 from the supply connection 30 through the inner portion 64 of the piston 44 to the second operating connection 36 is open.

[0049] FIG. 2 illustrates the hydraulic valve 12 according to FIG. 1 in a center position 57 in which the first operating connection 54 and the second operating connection 36 are closed independently from the check valves 46, 48. Both operating connections 34, 36 are closed by the control piston 44 so that no connection is provided between the two operating connection 34, 36 and the check valves 46, 48.

[0050] FIG. 3 illustrates the hydraulic valve 12 according to FIG. 1 in a second operating position 56 in which a second fluid path 72 of the hydraulic fluid from the second operating connection 36 through the check valve 48 associated with the second operating connection 36 to the first operating connection 3 is open. The check valve 48 can be opened by a hydraulic pressure provided at the second operating connection 36. FIG. 3 illustrates the check valve 48 in a closed condition with a contacting band shaped flexible element 80. Also the fluid path 74 from the supply connection 30 through the inner portion 64 of the piston 44 to the first operating connection is open.

[0051] FIG. 4 illustrates a check valve 46 according to an embodiment of the invention in a closed position in a longitudinal sectional view. The check valve 46 includes the fixation element 82 which can be configured cylindrical or hollow cylindrical (in FIG. 4 it is configured hollow cylindrical) and includes two axially offset portions with radially extending protrusions 92. The band shaped flexible element 80 is arranged about the fixation element 82 and between the two portions and axially fixated by the two protrusions 92 on the fixation element 82. The band shaped flexible element 80 is secured against displacement in the longitudinal direction L by the fixation element 82 axially enveloping the band shaped flexible element 80.

[0052] Two sleeves 84 envelop the fixation element 82 from both sides and are supported by the protrusions 92, wherein the band shaped flexible element 80 is preloaded and partially contacts the inside 88 of the sleeve 84 and thus closes the check valve 46, 48 in a condition where no pressure is provided. The check valve 46, 48 is thus configured as a preassembled integrated unit 86 which can be advantageously mounted as a whole in the inner portion 64 of the piston 44. The band shaped flexible element 80 is preloaded and contacts the inside 88 of the sleeves 84 and can be opened from the outside by a hydraulic pressure. The fixation element 82 thus forms a stop for the band shaped flexible element 80 in an inward direction.

[0053] FIG. 5 illustrates the check valve 46 according to FIG. 4 in an exploded view. Thus the individual components of the check valve 46 are separately illustrated in an assembly sequence: the fixation element 82 is illustrated as a center component of the check valve 46, the band shaped flexible element 80 which is positioned between the protrusions 92 of the fixation element 82 and the two sleeves 84 which are subsequently slid onto the protrusions 92 of the fixation element 82 from both ends. The band shaped flexible element 80 is thus moved slightly inward so that the element 80 contacts an inside 88 of the sleeves 84 with a preload and closes the check valve 46 in a condition without pressure. In the embodiment in FIG. 5, three protrusions 92 are illustrated respectively evenly distributed over the circumference of the fixation element 82, however also four or more protrusions 92 can be provided. Less than three protrusions 92 are also possible as long as the sleeves 84 can thus be supported on the fixation element 82.

[0054] In FIG. 6 the check valve 46 is illustrated according to FIG. 4 in an open position in a longitudinal sectional view. The band shaped flexible element 80 is pressed inward by a hydraulic pressure applied on the outside and contacts the inner stop of the fixation element 82. The fluid paths 52 thus opened are illustrated in FIG. 6. The two upper fluid paths 52 are illustrated in dashed lines in the drawing since they extend in front or behind the drawing plane since the protrusions 92 are cut in the drawing plane.

[0055] FIG. 7 illustrates a hydraulic valve 12 according to another embodiment of the invention in a longitudinal sectional view. In this hydraulic valve 12 two check vales 46, 48 are inserted which merely include one band shaped flexible element 80 which is arranged in the bore hole 50 of the piston 44 and secured with at least one annular fixation element 90 against a movement in the longitudinal direction L. The band shaped flexible element 80 in this embodiment contacts in unpressurized thus closed condition of the check valve 46, 48 with a preload directly at the inside 65 of the inner portion 64 of the piston 44 on one side at a stop of the bore hole 50 and is secured by the annular fixation element 90 which is pressed for example into the bore hole 50 against a movement in the longitudinal direction L.

[0056] FIG. 8 illustrates a hydraulic valve 12 according to another embodiment of the invention in a longitudinal sectional view. The check valves 46, 48 include fixation elements 82 similar to the check valve 46 illustrated in FIGS. 4 through 6, wherein the band shaped flexible element 80 is arranged between axially offset protrusions 92. In this embodiment, however, no sleeves 84 are being used, the fixation element 82 is pressed directly into the bore hole 50 of the inner portion 64 of the piston 44 so that the band shaped flexible element 80 in non-pressurized, thus closed condition of the check valves 46, 48 directly contacts the inside 65 of the inner portion 64 with a preload.

[0057] FIG. 9 illustrates a piston 94 of a hydraulic valve 12 according to an embodiment of the invention in an isometric view. The piston 44 includes bore holes 62 for hydraulically connecting the outside 66 of the piston 44 with the inner portion 64. The piston 44 furthermore includes bore holes 60 which provide another fluid path 75 of the hydraulic fluid from the outside 66 of the piston 44 to the check valves 46, 48 in the piston 44. Through these bore holes 60 the check valves 46, 48 arranged in an inner portion 64 of the piston 44 are loaded with hydraulic pressure. Since the piston 44 runs with a fit in the bore hole 42 of the bushing 15 of the hydraulic valve 12 a control groove 68 at least partially extending on an outside 66 of the piston 44 in a radial circumferential direction is provided for supplying the bore hole 60 with the hydraulic fluid so that the hydraulic fluid can penetrate on an outside 66 of the piston 44 through the control groove 68 into the bore holes 60.

[0058] FIG. 10 illustrates a piston 44 of a hydraulic valve 12 according to another embodiment of the invention wherein the hydraulic supply of the bore holes 60 is provided in another manner. In this embodiment the outside 66 of the piston 44 in the portion of the bore holes 60 is configured as a flat surface 70 in particular portions. The flat surfaces 70 are respectively provided with identical surfaces so that pressure loading does not cause any undesirable movement of the piston 44.

[0059] FIG. 11 illustrates a cam phaser 14 of a cam shaft 18 in a cross sectional view. The cam phaser 14 is provided to cooperate with a hydraulic valve 12 illustrated e.g. in FIGS. 1-3, wherein a first operating connection 34 is connected with a first pressure chamber 9 of the cam phaser 14 and a second operating connection is connected with a second pressure chamber 10 of the cam phaser 14. Thus, the first operating connection 34 and the second operating connection 36 are connectable by moving the piston 44 through at least one check valve 46, 48 as illustrated in FIGS. 4-6 alternatively with one another and/or with the supply connection 30 and/or with the at least one tank drain 48, 40. The at least one check valve 46, 48 is arranged in an inner portion of the piston 44. The check valve 46, 48 includes a band shaped flexible element 80 and releases a connection between an outside 66 and the piston 44 and an inner portion 64 of the piston 44 in an open position of the check valve 46, 48, wherein an inside 65 of the piston 44 includes an outer stop for the check valve 46, 48, so that the element 80 is openable in an inward direction by a hydraulic pressure provided at an outside 66 of the piston 44, in particular a pulsating hydraulic pressure.

[0060] A cam phaser 14 according to FIG. 11 is used to continuously adjust an angular position of the cam shaft 18 relative to the drive wheel 2 during operation of the internal combustion engine. Rotating the cam shaft 18 moves the opening and closing times of the gas control valves so that the internal combustion engine delivers optimum power at a respective speed. The cam phaser 14 includes a cylindrical stator 1 which is connected torque proof with the drive wheel 2. In the embodiment the drive wheel 2 is a chain sprocket over which a chain is run that is not illustrated in more detail. The drive sprocket 2 however can also be a drive belt that is used as a drive element. The stator 1 is operatively connected with the crank shaft through this drive element and the drive wheel 2.

[0061] The stator 1 includes a cylindrical stator base element 3 with bars 4 protruding from the stator base element 3 at an inside in a radially inward direction with uniform spacing. Intermediary spaces 5 are formed between adjacent bars 4 wherein a hydraulic fluid is introduced into the intermediary spaces for example through a hydraulic valve 12 that is illustrated in more detail in FIGS. 1-3. The hydraulic valve 12 is thus configured as a non-central valve but it can also be configured as a central valve in a particular embodiment. Between adjacent bars 4 blades 6 protrude which extend in a radially outward direction from a cylindrical rotor hub 7 of a rotor 8. The blades 6 divide the intermediary spaces 5 between the bars 4 respectively into two respective pressure chambers 9 and 10.

[0062] The bars 4 contact an outer enveloping surface of the rotor hub 7 with their faces in a sealing manner. The blades 6 contact in turn a cylindrical wall of the stator base element 3 with faces of the blades in a sealing manner.

[0063] The rotor 8 is connected torque proof with the cam shaft 18. In order to change an angular position between the cam shaft 18 and the drive wheel 2 the rotor 8 is rotated relative to the stator 1. Thus, hydraulic fluid in the pressure chambers 9 or 10 is pressurized as a function of a desired direction of rotation, whereas the other pressure chambers 10 or 9 are released towards the tank of the hydraulic fluid. In order to pivot the rotor 8 relative to the stator 1 counter clockwise into the illustrated position the hydraulic valve 12 pressurizes an annular first rotor channel in the rotor hub 7. From this first rotor channel additional channels 11 lead into the pressure chambers 10. This first rotor channel is associated with the first operating connection 34. In order to pivot the rotor 8 clockwise the hydraulic valve 12 pressurizes a second annular rotor channel in the rotor hub 7. This second rotor channel is associated with the second operating connection 36. The two rotor channels are axially offset from each other relative to a center axis 22.

[0064] The cam phaser 14 is placed onto the cam shaft 18 configured as a hollow tube 16. Thus, the rotor 8 is placed onto the cam shaft 18. The phaser 14 is pivotable by the hydraulic valve 12 illustrated in FIG. 2.