HYDRAULIC VALVE FOR A CAM PHASER

Abstract

A hydraulic valve for a cam phaser and including a housing; a hollow cylindrical piston which is supported axially movable in a central opening extending along a longitudinal axis of the housing; a supply connection feeding a hydraulic fluid; and at least a first operating connection, a second operating connection and a tank connection, wherein one of the first operating connection or the second operating connection is connectable through an interior space of the piston with the supply connection and another of the first operating connection or the second operating connection is connectable with the tank connection as a function of a position of a position of the piston along the longitudinal axis of the housing, wherein the piston includes a first flow through opening and a second flow through opening connecting the interior space of the piston with the first operating connection and the second operating connection.

Claims

1. A hydraulic valve for a cam phaser, the hydraulic valve comprising: a housing; a hollow cylindrical piston which is supported axially movable in a central opening extending along a longitudinal axis of the housing; a supply connection feeding a hydraulic fluid; and at least a first operating connection, a second operating connection and a tank connection, wherein one of the first operating connection or the second operating connection is connectable through an interior space of the piston with the supply connection and another of the first operating connection or the second operating connection is connectable with the tank connection as a function of a position of a position of the piston along the longitudinal axis of the housing, wherein the piston includes a first flow through opening and a second flow through opening connecting the interior space of the piston with the first operating connection and the second operating connection, wherein the first flow through opening is associated with the first operating connection and the second flow through opening is associated with the second operating connection, wherein the piston includes a third flow through opening arranged between the first flow through opening and the second flow through opening, wherein the third flow through opening is configured for hydraulic fluid to flow from the first operating connection into the interior space of the piston and from the second operating connection into the interior space of the piston, and wherein the third flow through opening is closable by a check valve arranged in the interior space of the piston to stop a flow of the hydraulic fluid from the interior space of the piston to the first operating connection and the second operating connection.

2. The hydraulic valve according to claim 1, wherein the check valve is fixated by a fixation element.

3. The hydraulic valve according to one of the claim 1, wherein the check valve is configured band shaped.

4. The hydraulic valve according to claim 2, wherein the fixation element is configured disc shaped to provide a movement limitation for the check valve.

5. The hydraulic valve according to claim 2, wherein the fixation element is configured flowable.

6. The hydraulic valve according to claim 2, wherein the fixation element (70) is configured in two components, wherein a first component of the two components is configured to provide a movement limitation of the check valve and a second component of the two components is configured to securely position the first component.

7. The hydraulic valve according to claim 2, wherein the fixation element includes at least one contact surface that is in contact with an inner wall of the piston and which includes a beveled or outward cambered edge surface.

8. The hydraulic valve according to claim 2, wherein the fixation element includes at least one cambered outer surface which is flowable by the hydraulic fluid.

9. The hydraulic valve according to claim 2, wherein a height of a first portion of the fixation element which is provided for supporting the fixation element corresponds at least to a diameter of the interior space of the piston.

10. The hydraulic valve according to claim 9, wherein a portion of the fixation element which is provided for limiting a movement of the check valve has a partial height which is less than the height of the first portion.

11. The hydraulic valve according to claim 1, wherein the piston includes a flow out channel to establish a flow connection between the first operating connection, the second operating connection and a third connection opening provided in the housing, and wherein the third connection opening is flow connectable with the tank connection of the hydraulic valve.

12. The hydraulic valve according to claim 1, wherein the housing includes an flow out channel to establish a flow connection between the first operating connection, the second operating connection and the third connection opening provided in the housing, and wherein the third connection opening is flow connectable with the tank connection of the hydraulic valve.

13. The hydraulic valve according to claim 12, wherein the supply connection is arranged at an end of the tubular housing, and wherein the housing is configured tubular.

14. The hydraulic valve according to claim 1, wherein the hydraulic valve is configured as a central valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Further advantages and detail of the invention can be derived from the subsequent description of advantageous embodiments and from the drawing figures. The features and feature combinations recited supra in the description and recited in the subsequent figure description and/or features and feature combinations only shown in the drawings are not only usable in the respectively cited combination but also in other combinations or by themselves without departing from the spirit and scope of the invention. Identical or functionally equivalent elements are provided with identical reference numerals. For the purpose of clarity it is possible that the elements are not provided with reference numerals in all figures without losing their association, wherein:

[0031] FIG. 1 illustrates a longitudinal sectional view of a hydraulic valve according to the invention for a cam phaser in a first embodiment;

[0032] FIG. 2 illustrates a longitudinal sectional view of the hydraulic valve according to FIG. 1 in a first position;

[0033] FIG. 3 illustrates a longitudinal sectional view of the hydraulic valve according to the invention in a second embodiment in the first position;

[0034] FIG. 4 illustrates a longitudinal sectional view of the hydraulic valve according to FIG. 1 in a second position;

[0035] FIG. 5 illustrates a longitudinal sectional view of the hydraulic valve according to FIG. 1 in a third position;

[0036] FIG. 6 illustrates a symbolic view of the hydraulic valve;

[0037] FIG. 7 illustrates an exploded view of the piston according to the invention of the hydraulic valve according to FIG. 1;

[0038] FIG. 8 illustrates an exploded view of the hydraulic valve according to FIG. 1;

[0039] FIG. 9 illustrates a perspective view of a fixation element of the hydraulic valve according to the invention; and

[0040] FIG. 10 illustrates a perspective view of a piston cover of a hydraulic valve according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0041] A hydraulic valve 10 according to the invention for a phaser that is not illustrated in more detail of a cam shaft that is not illustrated in more detail is configured according to FIG. 1 in a first embodiment. The hydraulic valve 10 is configured to be received as a central valve in a rotor of the cam phaser that is not illustrated in more detail. This means put differently that the hydraulic valve 10 is received in a central opening of the cam phaser and at least partially enveloped by the cam phaser.

[0042] The hydraulic valve 10 includes a housing 12 which is configured flowable. In order to hydraulically supply the cam phaser plural connections A, B, P, T are provided at the housing 12. In the housing 12 a piston 16 that is axially movable in a central opening of the housing 12 is received and axially movable along a longitudinal axis of the hydraulic valve 10. The housing 12 is configured substantially tubular. The cam phaser facilitates a change of opening and closing times of the internal combustion engine during an operation of the internal combustion engine that is not shown in more detail. Thus, the cam phaser continuously adapts a relative angular position of a cam shaft of the internal combustion engine that is not illustrated in more detail relative to a crank shaft of the internal combustion engine that is not illustrated in more detail, wherein the cam shaft is rotated relative to the crank shaft. The relative rotation of the cam shaft moves the opening and closing times of the gas control valves so that the internal combustion engine delivers an optimum power at a respective speed.

[0043] A stator of the cam phaser that is not illustrated in more detail is connected torque proof with a drive gear of the cam shaft that is not illustrated in more detail. At insides of a stator base element radially inward extending bars are configured in uniform intervals so that an intermediary space is formed respectively between two adjacent bars. A blade that is not illustrated in more detail of a rotor hub of the rotor that is not illustrated in more detail is arranged so that it protrudes into the intermediary space. Corresponding to the number of the intermediary spaces the rotor hub has a number of blades, thus the blades divide each intermediary space into two pressure cavities. A pressure medium, typically a hydraulic fluid is introduced into these partial spaces in a controlled manner by the hydraulic valve 10.

[0044] A pressure cavity is associated with each operating connection A, B. Thus the first pressure cavity is associated with the first operating connection A and the second pressure cavity is associated with the second operating connection B. In order to connect with the pressure cavities the first operating connection A includes a first connection opening 66 configured in the housing 12 and the second operating connection B includes a second connection opening 68 configured in the housing 12. In order to change an angular position between the cam shaft and the crank shaft the pressure medium in the first pressure cavity or in the second pressure cavity is pressurized while the second pressure cavity or the first pressure cavity is unloaded. The unloading is performed through the tank connection T wherein the hydraulic fluid can drain through the tank connection T.

[0045] The hydraulic valve 10 according to the invention is depicted in FIG. 1 in a longitudinal sectional view. The piston 16 is configured hollow cylindrical and includes a first flow through opening 20, a second flow through opening 22 and a third flow through opening 24. Each flow through opening 20, 22 and 24 includes at least one, advantageously two radial piston bore holes. The first flow through opening 20 is associated with the first operating connection A, the second flow through opening 22 is associated with the second operating connection B and the third flow through opening 24 is configured as a function of a positioning of the piston 16 to provide a flow connection of the first operating connection A or the second operating connection B with the inner space 26 in order to use cam shaft torques from the pressure cavity that is to be emptied to fill the pressure cavity that is to be filled more quickly as will be described infra.

[0046] In order for the hydraulic fluid to flow out of the hydraulic valve 10 through the tank connection T into a provided tank that is not illustrated in more detail the hydraulic valve 10 includes a flow out channel 28 which extends in the first embodiment substantially in a direction of the longitudinal axis 14 in the piston 16.

[0047] A return flow of the fluid into the supply connection P is prevented by a first check valve 30 which is arranged in a portion of a first end 32 of the housing 12 at which the central opening 18 is flow connected with the supply connection P downstream of a fluid filter that is positioned in the housing 12 using a safety element 34 to secure the fluid filter in position. Between the first check valve 30 which is configured as an annular check valve and the fluid filter 36 a flow disc 38 is received in the housing 12 whose disc opening 40 are closeable by the first check valve 30 and through which hydraulic fluid moves from the supply connection P into the hydraulic valve 10.

[0048] The first check valve 30 is pressure loaded by the first tension element 42 in a direction towards the flow disc 38. This means put differently the check valve is pressed against the flow disc 38 by the first preload element 42 in order to close the disc openings 40. As soon as the hydraulic fluid flowing through the supply connection P has a pressure which is greater than a preload force of the first preload element 42 the first check valve 30 lifts off from the flow disc 38 and the hydraulic fluid enters through the disc openings 40 into an inlet channel 44 of the piston 16 that is flow connected with the inner cavity 26.

[0049] In order to arrest and support the piston 16 the piston includes a pinion shaped support element 48 at a first piston end 46 which pinion shaped support element at least partially includes the inlet channel 44. The support element 48 engages an arresting cover 50 and is received therein, wherein the arresting cover is used for calibrating the hydraulic valve 10 in addition to arresting and supporting the guide element 48. Furthermore the arresting cover 50 is used for supporting the first preload element 42 at a side that is oriented away from the first check valve 30. The support element 48 is arranged so that it engages a central cover opening 42 of the arresting cover 50.

[0050] The piston 16 is operatively connected with an actuator that is not illustrated in more detail at a second piston end 54 that is oriented away from the first piston end 46. At the second piston end 54 a piston cover 56 is positioned which closes the inner cavity 26 against an outflow of the fluid. Furthermore an actuator plunger that is not illustrated in more detail can engage the piston cover 56 at a cover surface 58 that is configured oriented away from the inner cavity 26 so that the piston 16 is positioned in the central opening 18 using the actuator 16. The piston cover 56 is fixated in the housing 12 using an additional safety element 60.

[0051] In order to safely position the piston 16 a second preload element 62 is provided which is arranged between the piston 16 and the arrester cover 50 in the central opening 18.

[0052] The hydraulic valve 10 according to the invention includes a second check valve 64 to secure the third flow through opening 24 against an outflow of hydraulic fluid from the inner space 26 in a direction towards the operating connections A, B.

[0053] In order to direct the fluid and secure the position of the second check valve 64 a fixation element 70 is arranged in the housing 12 so that it fixates the second check valve 64.

[0054] FIG. 2 illustrates a longitudinal sectional view of the hydraulic valve 10 according to FIG. 1 in a first position wherein flow through directions of the hydraulic fluid are indicated by flow lines 72, 74, and 76 in this first position. The second opening connection B is connected through the inner cavity 26, the second flow through opening 22 and the second connection opening 68 with the supply connection P as illustrated by the second flow line 74. Additionally pressure is feedable under the occurring cam shaft torques in the pressure cavity associated with the first operating connection A starting from the first operating connection A through the third flow through opening 24 and the inner space 26 in the second operating connection B, as soon as the second check valve 64 is opened due to the pressure of the cam shaft torques as illustrated by the first flow line 72.

[0055] Since the hydraulic fluid can flow from the first operating connection A at least partially into the second operating connection B a reaction time of filling the pressure cavity associated with the operating connection B can be significantly reduced. Furthermore starting from the first operating connection A, hydraulic fluid flows through the flow out channel 28 into a third connection opening 78 configured in the housing 12 which is flow connected with the tank connection T as illustrated by the third flow line 76.

[0056] The flow through openings 20, 22 and 24 are respectively configured in a ring groove 21, 23 and 25, wherein the first flow through opening 20 is associated with the first ring groove 21, the second flow through opening 22 is associated with the second ring groove 23 and the third flow through opening 24 is associated with the third ring groove 25. The ring grooves 21, 23 and 25 form control edges which cause an opening and/or closing of the connection openings 66, 67, and 68.

[0057] The flow out channel 28 is flow connected with the third ring groove 25 which includes a first control edge 82 and a second control edge 84. The first control edge 82 releases the first connection opening 66 whereas the second control edge 84 blocks the second connection opening 68. Thus, hydraulic fluid can flow from the first operating connection A through the third ring groove 25 into the flow out channel 28 which is flow connected with the third connection opening 78.

[0058] FIG. 3 illustrates a longitudinal sectional view of the hydraulic valve 10 according to the invention in a second embodiment in the first position. The second embodiment differs from the first embodiment through the arrangement of the flow out channel 28 which is flow connected with the third connection opening 78 which is arranged in the second embodiment at a second end 80 of the housing 12 which is configured oriented away from the first end.

[0059] The flow out channel 28 is configured in the second embodiment of the hydraulic valve 10 according to the invention in the housing 12. Between the first connection opening 66 and the second connection opening 68 the flow out channel 28 branches off in the housing 12 so that like in the first embodiment hydraulic fluid can run through the third ring groove 25 into the flow out channel 28. This means put differently that the channel entry 29 of the flow out channel 28 is configured between the first connection opening 66 and the second connection opening 68. Compared therewith the channel entry 29 of the hydraulic valve 10 is configured according to the first embodiment in the piston 16 in the third ring groove 25.

[0060] In FIGS. 4 and 5, the hydraulic valve 10 according to the first embodiment is illustrated in two additional positions, a second position and a third position. In FIG. 4 the first connection opening 66 and the second connection opening 68 are closed through respective positioning of the piston 16 and thus using the control edges 82, 84 of the third ring groove.

[0061] FIG. 5 illustrates the piston 16 in the third position in which the first operating connection A is connected through the inner space 26, the first flow through opening 20 and the first connection opening 66 with the supply connection P. Additionally hydraulic fluid is feedable at prevailing cam torques in the pressure cavity associated with the second operating connection B starting from the second operating connection B through the third flow through opening 24 and the inner space 26 into the first operating connection A as soon as the second check valve 64 is opened due to the pressure of the cam torques. Furthermore the second operating connection B is connected through the first ring groove 25 with the flow out channel 28 and thus with the tank drain T.

[0062] FIG. 6 illustrates the hydraulic valve 10 according to the invention in a symbolic representation. The left switching position corresponds to the first position of the piston 16 in which hydraulic fluid flows from the first operating connection A into the second operating connection B which is filled with the hydraulic fluid from the supply connection P. The right switching piston corresponds to the third position of the piston 16 in which hydraulic fluid flows from the second operating connection B into the first operating connection A and the first operating connection A is filled with hydraulic fluid from the supply connection P. Also in this third position a reaction time for filling the first pressure cavity associated with the operating connection A is substantially reduced since hydraulic fluid can flow from the second operating connection B at least partially into the first operating connection A.

[0063] In the center switching position which corresponds to the second position of the piston 16 as illustrated in FIG. 4 the operating connections A, B are blocked against flow through.

[0064] To further illustrate the invention FIG. 7 depicts the piston 16 according to the invention of the first embodiment in an exploded view and FIG. 8 depicts the hydraulic valve 10 according to the invention according to the first embodiment also in the exploded view.

[0065] The piston 16 according to the invention and accordingly the hydraulic valve 10 according to the invention includes a second check valve 64 in the portion of the third flow through opening 24 in order to prevent a reverse flow of the hydraulic fluid. Put differently this means that the second check valve 64 facilitates a flow of hydraulic fluid from the consumer connections A, B through the third flow through opening 24 into the inner cavity 26 but not vice versa, since the hydraulic fluid presses the second check valve 64 against the third flow through opening 24.

[0066] The second check valve 64 is positioned by the fixation element 70 in the interior space 26 of the piston 16. The fixation element 70 is illustrated in FIG. 9 in a perspective view. The fixation element is configured to prevent a flow deviation or flow separation of the hydraulic fluid flowing through the piston 16 so that a reaction time of the piston 16 and thus of the cam phaser is not influenced unfavorably.

[0067] The fixation element 70 which is configured disc shaped includes a support frame 86 which limits a contraction of the second check valve 64 which is configured band shaped. Thus, it suffices to configure the boundary in a single plane which is achieved by the support frame 86. In order for the flow of the hydraulic fluid to remain unimpeded, the support frame 86 is flowable which is facilitated by a frame opening 88.

[0068] The support frame 86 is configured rounded at its outer surfaces 90, so that turbulence of the hydraulic fluid is prevented. In order to safely position the support frame 86 the fixation element 70 includes a double T shaped handle 91 which supports the support frame 86.

[0069] The fixation element 70 is supported on one side at a first element end 92 which is oriented towards the first end 32 of the housing 12 at a shoulder 94 formed in an interior 26 of the piston 16, so that the shoulder 94 provides an axial stop during assembly. On the other side the fixation element 70 is supported at its second element end 93 at the piston cover 56 wherein closing the inner space 26 with the piston cover 56 which is illustrated in FIG. 10 in a perspective view wedges and positions the fixation element 70 in the interior space 26. This means put differently that the fixation element 70 is configured in two components, wherein the support frame 86 is provided as a first component for movement limitation of the second check valve 64 and the handle 91 is provided as a second component to safely position the support frame 86.

[0070] The handle 91 includes a first transversal beam 96 which is used for support at the piston cover 56 and a second transversal beam 98 connected by a connecting rod 100 of the handle 91 with the first transversal beam 96. The second transversal beam 98 is permanently connected with the support frame 86.

[0071] The two transversal beams 96, 98 include a height H extending in a radial direction of the cylindrical inner space 26 wherein the height H corresponds to a diameter D of the section of the inner space 26 in which the fixation element 70 is received.

[0072] In order to simplify assembly which includes inserting the fixation element 70 into the inner space 26 starting from the second end 80 of the housing 12 the transversal beams 96, 98 include edge surfaces 106 at contact surfaces 104 oriented towards an inner wall 102 of the piston 16, wherein the edge surfaces are outward cambered and thus convex. By the same token the edge surfaces 106 can also be configured as a bevel.

[0073] The edge surfaces 104 are configured complementary to the inner wall 102. This means put differently that the contact surfaces 104 are configured adapted to a camber of the inner wall 102. Thus, the fixation element 70 can be safely inserted into the piston 16 without wedging.

[0074] In order to provide mobility for the second check valve 64 a support frame height h is configured smaller than the height H. Thus, a movement space 108 between the support frame 106 and the inner wall 102 is provided in which the second check valve 64 can contract or expand unimpeded.

[0075] Overall the fixation element 70 is configured flow optimized by the edge surfaces 106, the cambered contact surfaces 104 and by radii R configured in the frame opening 88 and at transitions between the transversal beams 96, 98 and the connection rod 100 so that a flow separation that is typical at sharp edges is prevented.