CAMSHAFT ADJUSTER WITH A CENTRAL VALVE AND WITHOUT A T BRANCH

Abstract

A hydraulic camshaft adjuster having: a stator with a radially inwardly opening working chamber a rotor arranged radially within the stator, wherein the rotor receives a vane dividing the working chamber into two part chambers, and rotatable relative to the stator about a rotational axis dependent on a hydraulic pressure set in the part chambers . A central valve controls the hydraulic pressure and is configured for selectively connecting individual hydraulic lines which open into the part chambers among one another and/or to a supply line.A check valve device is integrated per part chamber into a first hydraulic line configured in the vane, which check valve device is arranged to act in a permanently closing manner in a first hydraulic flow direction from the central valve into the respective part chamber and can be opened dependent on the hydraulic pressure in a second hydraulic flow direction which is opposed to the first hydraulic flow direction.

Claims

1-10. (canceled)

11. A vane cell hydraulic camshaft adjuster comprising: a stator with a radially inwardly opening working chamber; a rotor situated radially within the stator, the rotor accommodating a vane extending into the working chamber dividing the working chamber into first and second subchambers, the rotor being rotatable relative to the stator about a rotation axis as a function of a hydraulic pressure set in the first and second subchambers, and a central valve controlling the hydraulic pressure and designed for selectively connecting individual hydraulic lines, opening into the first and second subchambers to one another or to a supply line; for each of the first and second subchambers, a respective check valve device being integrated into a first hydraulic line provided in the vane so as to define first and second check valve devices, the first and second check valve devices being situated to act in a permanently blocking manner in a first hydraulic flow direction from the central valve into the respective first or second subchamber, and openable in a second hydraulic flow direction opposite the first hydraulic flow direction.

12. The camshaft adjuster as recited in claim 11 wherein first check valve device is situated in the first hydraulic line toward one side of the first subchamber.

13. The camshaft adjuster as recited in claim 11 wherein the second check valve device is situated in the first hydraulic line toward one side of the second subchamber.

14. The camshaft adjuster as recited in claim 11 wherein the first and second check valve devices are inserted into an inner cavity of the vane.

15. The camshaft adjuster as recited in claim 11 wherein each of the first and second check valve devices is designed as a sheet metal part, a sheet metal section of the particular first or second check valve device being elastically bendable in the second hydraulic flow direction.

16. The camshaft adjuster as recited in claim 11 wherein the first hydraulic line is connected to the central valve, passing radially inwardly from the vane through the rotor.

17. The camshaft adjuster as recited in claim 11 wherein a second hydraulic line directly connects the first subchamber to the central valve.

18. The camshaft adjuster as recited in claim 11 wherein a third hydraulic line directly connects the second subchamber to the central valve.

19. The camshaft adjuster as recited in claim 11 wherein the supply line is connectable to a pump conveying a hydraulic medium in the direction of the central valve, a third check valve device being integrated into the supply line.

20. The camshaft adjuster as recited in claim 11 wherein the camshaft adjuster is adjustable as a function of a torque applied to the rotor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention is explained in greater detail below with reference to the figures, in conjunction with which various specific embodiments are also explained.

[0020] FIG. 1 shows a cross-sectional illustration of a camshaft adjuster according to the present invention according to a first specific embodiment, in particular the configuration and the design of the first hydraulic line in the vane and in the rotor being apparent, and the pressure fluid flowing in a second hydraulic flow direction being denoted by an arrow;

[0021] FIG. 2 shows the same cross-sectional illustration of the camshaft adjuster illustrated in FIG. 1, but with the hydraulic medium now being depicted as flowing or pushing in the first hydraulic flow direction;

[0022] FIG. 3 shows a longitudinal section illustration of the camshaft adjuster according to the present invention according to FIG. 1, in which the arrangement of the camshaft adjuster at one end of a camshaft is particularly clearly apparent, and an adjustment actuator that acts on the central valve is apparent, the section plane extending along the rotation axis of the camshaft adjuster;

[0023] FIG. 4 shows a longitudinal section illustration of the camshaft adjuster according to the first specific embodiment, the illustration being similar to FIG. 3, except that the camshaft adjuster together with the camshaft are now sectioned in a plane that is rotated with respect to the section plane in FIG. 3;

[0024] FIG. 5 shows a detailed view of the camshaft adjuster according to the present invention in the section according to FIG. 3, the various flow directions that are settable by the central valve inside the camshaft adjuster being denoted by arrows for better clarity;

[0025] FIG. 6 shows a detailed view of the camshaft adjuster according to the present invention in the section according to FIG. 4, in this case the rotor being sectioned in an angular range in which the first hydraulic line is situated, and once again a flow arrow being illustrated which depicts a push of hydraulic medium from the supply line, via the central valve, toward the check valve;

[0026] FIG. 7 shows a detailed view of the central valve in a section area as illustrated in FIG. 6, the various flow directions and flow conditions within the central valve being particularly clearly apparent, and the supply line on the side of the pump being connected to the interior of the central valve; and

[0027] FIG. 8 shows a detailed view of the central valve in a section area as illustrated in FIG. 5, the central valve being in that position in which the first subchamber is connected to the central valve, but the second subchamber is blocked with respect to the first subchamber, so that the two subchambers are also decoupled from one another.

DETAILED DESCRIPTION

[0028] 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.

[0029] The basic design of hydraulic camshaft adjuster 1 according to the present invention is particularly clearly apparent in conjunction with FIGS. 1 through 4. Hydraulic camshaft adjuster 1 has a design of the vane cell construction/vane cell type. Camshaft adjuster 1 according to the present invention has essentially the same design and function as the camshaft adjuster in DE 10 2010 019 530 A1 so that this publication is considered to be incorporated by reference herein.

[0030] As is customary, hydraulic camshaft adjuster 1 includes a stator 2 with means, namely, external teeth, which are designed for connection to a traction mechanism drive in a rotatably fixed manner. In the operating state of an internal combustion engine, this stator 2 is thus connected to an output shaft of the internal combustion engine in a rotatably fixed manner. Stator 2 has a radially inwardly opening working chamber 3. Upon further inspection, it is apparent that stator 2 has not just one working chamber 3, but, rather, has four working chambers 3, which are spaced apart from one another along the circumference (of stator 2). A vane 7 connected to a rotor 6 is accommodated within each of these geometrically separated working chambers 3. Rotor 6 is in turn radially supported so that it is rotatable within stator 2. Vane 7, which is situated on an outer side/outer circumferential side of rotor 6 in a rotatably fixed manner, in turn extends into working chamber 3 in the radial direction. Vane 7 protrudes into working chamber 3 associated with it in such a way that vane 7 divides working chamber 3 into two partial working chambers/subchambers 4 and 5 that are independently hydraulically controllable.

[0031] In the operating state of the internal combustion engine/camshaft adjuster 1, rotor 6 is in turn connected to a camshaft 23 of the internal combustion engine in a rotatably fixed manner, as is customary. Upon further inspection, it is apparent that rotor 6 has one vane 7 for each working chamber 3 of stator 2, with only one vane 7 being inserted/protruding into each working chamber 3. Vane 7 is in sealing contact with stator 2, so that in the operating state, the two partial working chambers 4 and 5 of a working chamber 3 are sealed and fillable with hydraulic medium independently of one another. Camshaft adjuster 1 is thus adjusted/set as a function of the set hydraulic pressure in subchambers 4 and 5. Rotor 6 is set in the desired rotary position relative to stator 2 about a rotation axis 8 (FIG. 3) as a function of the hydraulic pressure.

[0032] In addition, camshaft adjuster 1 includes a central valve 9 which is designed for selectively connecting the individual hydraulic lines 10, 11, 12, opening into subchambers 4 and 5, to one another or to a supply line 13. Central valve 9 controls the relative rotary position that is to be achieved between rotor 6 and stator 2, as a function of the position of the central valve/the position of its piston 16 which is displaceable in the axial direction, and allows the desired hydraulic pressure to be set in the particular subchamber 4 or 5.

[0033] A first hydraulic line 10 is introduced into each vane 7; in the discussion below, only one vane 7, one working chamber 3 associated with this vane 7, and the two subchambers 4 and 5 associated with this working chamber 3 are described by way of example. First hydraulic line 10 extends within vane 7 essentially in a straight line in the radial direction. First hydraulic line 10 merges into rotor 6 at a radial inner side of vane 7 in the area where vane 7 is connected to rotor 6. First hydraulic line 10 is therefore introduced with a first (radially outer) section into vane 7, and is introduced with a second (radially inner) section into rotor 6. First hydraulic line 10 extends through rotor 6 in the radial direction, and is open at an inner side of rotor 6 facing central valve 9. When central valve 9 is installed, it is therefore connected to this first hydraulic line 10.

[0034] First hydraulic line 10 is divided into two line portions 18 and 19 in vane 7. A line portion 18 or 19 opens into a subchamber 4 or 5, respectively. In FIG. 1, first hydraulic line 10 opens into first subchamber 4 with a first line portion 18 extending along the circumference in the counterclockwise direction, and opens into second subchamber 5 with a second line portion 19 extending along the circumference in the clockwise direction.

[0035] In the transition area between first hydraulic line 10 and first subchamber 4, i.e., in first line portion 18, a first check valve device 14 is situated/installed/inserted in vane 7, and in the transition area between first hydraulic line 10 and second subchamber 5, i.e., in second line portion 19, a second check valve device 15 is situated/installed/inserted in vane 7.

[0036] Each check valve device 14 and 15 acts as a check valve. Each check valve device 14 and 15 is formed by a sheet metal section 20 or 21. Both sheet metal sections 20 and 21 are an integral part of a sheet metal part which essentially has a bracket/pear/Ω shape. Each of sheet metal sections 20 and 21 is designed as a strip-shaped sheet metal section 20 or 21 that is elastically deformable/bendable. Sheet metal sections 20 and 21 are situated and configured in such a way that they open only beginning at a certain pressure difference between first hydraulic line 10 and the particular subchamber 4 and 5, when a hydraulic fluid is pushed from the particular subchamber 4 and 5 into first hydraulic line 10. This direction is referred to as the second hydraulic flow direction. In turn, during operation of camshaft adjuster 1, sheet metal sections 20 and 21 have a continuously blocking action in a first hydraulic flow direction that is opposite this second hydraulic flow direction. In other words, check valve devices 14 and 15 are designed in the form of a sheet metal part that is configured essentially as a sheet metal bracket. This sheet metal part is inserted into a cavity 22 inside vane 7, namely, snapped in place/locked in place, for example, and is therefore held in a form-fit and/or force-fit manner.

[0037] First sheet metal section 20 is thus designed as first check valve device 14, and is situated in such a way that it elastically deforms and allows a hydraulic medium flow from first subchamber 4 into first hydraulic line 10 when the pressure within first subchamber 4 is greater than in first hydraulic line 10. The hydraulic medium then flows from first subchamber 4, via first sheet metal strip 20 which is then deformed, into first hydraulic line 10 and thus to central valve 9. If the hydraulic pressure within second subchamber 5 is higher than in first hydraulic line 10 in another position of camshaft adjuster 1, as illustrated in FIG. 1, second sheet metal section 21 is elastically deformed in such a way that it allows a hydraulic medium flow from second subchamber 5 into first hydraulic line 10 and thus toward central valve 9. In this additional position, hydraulic medium may thus flow from second subchamber 5 into central valve 9, from where it is then fed into first subchamber 4. The two sheet metal sections 20 and 21 thus directly take on the function of the check valve.

[0038] In the first hydraulic flow direction, as is clearly apparent in FIG. 2, these two sheet metal sections 20 and 21 then act once again in such a way that they are positioned so that they close/seal off the particular line portions 18 and 19 and prevent/block flow of a hydraulic medium from first hydraulic line 10 into the particular subchamber 4 or 5.

[0039] As is also particularly clearly apparent in FIG. 4, first hydraulic line 10 extends essentially centrally, i.e., centrally in the axial direction of the rotor. First hydraulic line 10 is designed as a linear borehole that extends from vane 7 toward central valve 9. For each subchamber 4 and 5, an additional hydraulic line 11 or 12 extends from central valve 9 into subchamber 4 or 5, respectively, next to first hydraulic line 10. First subchamber 4 is connected directly to central valve 9 with the aid of a second hydraulic line 11 that extends inwardly in the radial direction, and second subchamber 5 is connected directly to central valve 9 with the aid of a further, third hydraulic line 12 that extends inwardly in the radial direction. The various hydraulic lines 10, 11, and 12 are particularly clearly apparent in FIG. 5; their directions of extension are provided with the associated reference arrows. A first reference arrow denoted by reference numeral 24 depicts the direction of extension of first hydraulic line 10. A second reference arrow denoted by reference numeral 25 depicts the direction of extension of second hydraulic line 11. A third reference arrow denoted by reference numeral 26 depicts the direction of extension of third hydraulic line 12.

[0040] Supply line 13 adjoining central valve 9 extends further to a pump, not illustrated here for the sake of clarity, and into the interior of central valve 9. With the aid of a third check valve device 17 which likewise is designed as a check valve, the first section of supply line 13, which extends outside of central valve 9, may be blocked with respect to a second section of supply line 13 that extends within central valve 9. Supply line 13 thus connects the pump/supply pump directly to the interior of central valve 9 as a function of the position of third check valve device 17. Third check valve device 17 acts in such a way that from the pump, it opens in a first flow direction of hydraulic medium (denoted by fourth reference arrow 27) into central valve 9 and into the particular hydraulic lines 10, 11, 12, beginning at a certain, higher hydraulic pressure in the first section with respect to the interior of central valve 9/the second section (FIGS. 6 and 7). Third check valve device 17 permanently blocks in a second flow direction opposite this first flow direction, i.e., out of the central valve and toward the pump (FIGS. 5 and 8). As illustrated in FIG. 7, in a first operating position/a first operating state it is thus possible to always supply the interior of central valve 9 with the desired operating pressure, and to use camshaft adjuster 1 as an OPA camshaft adjuster. On the other hand, as is particularly clearly apparent in FIG. 8, in a second operating position/a second operating state it is possible to decouple the interior of central valve 9 from the pump, and via second and third hydraulic lines 11 and 12 to control subchambers 4 and 5 independently of the operating pressure specified by the pump, in which case camshaft adjuster 1 is then used as a CTA camshaft adjuster.

[0041] In other words, unlike the case for the adjusters known thus far, at least one rotor vane (vane 7) is provided with a check valve 14, 15 in the interior of camshaft adjuster 1 of the type according to the present invention. Two check valves 14, 15 are integrated into each vane 7. Check valve 14, 15 is situated in vane 7, and may open and close in both directions (from first subchamber 4 into first hydraulic line 10 and from second subchamber 5 into first hydraulic line 10), depending on the pressure difference. Check valve 14, 15 radially conducts the transmitted oil/hydraulic medium from chamber A (first subchamber 4) or chamber B (second subchamber 5) into central valve 9, and is thus connected to oil channel P (supply channel/pressure channel/supply line 13). Rotor 6 includes a third oil channel (first hydraulic line 10, a so-called R channel). The third oil channel is situated in the axial center, but may also be situated outside, i.e., not in the axial center. Adjuster 1 does not include a T branch (tank outlet). The mode of operation may be explained as follows: Adjuster 1 and central valve 9 are initially filled at a fairly low oil pressure, so that no air is in the system. No T branch is present in the system; i.e., for the oil filling it is sufficient when the oil expels the air that is present, via leakage. If an excess pressure, which arises due to alternating torques, occurs in chamber A or B, check valves 14, 15 become active and allow excess pressure to escape through central valve 9 to the P channel (supply line 13) in central valve 9. Since the pressure is not able to flow back out of central valve 9, namely, toward the pump, on account of the central valve check valve (third check valve device 17), excess pressure is introduced into chamber A or B (subchamber 14 and 15). If an excess pressure should arise in chambers A (14) or B (15) due to an alternating torque, and which is not intended to be adjusted, the excess pressure may be introduced via oil channel A (11) or oil channel B (12) back into central valve 9, and there may be introduced into P chamber (13) or R chamber (10). This results in equal pressures everywhere, and check valve 14, 15 is no longer able to open, also due to the elastic pretension. Hydraulic support is thus provided, and adjuster 1 is no longer able to move in an unintended direction. Central valve 9 is provided with additional channel R (first hydraulic line 10), which is connected directly to P channel (supply line 13/first section of supply line 13). Since oil migration between the A chamber and B chamber develops and no oil exits the tank, adjuster system 1 requires no additional supply pressures. This is necessary only for the supply pressure that has been lost to the outside due to leakage. There would be no oil loss if an even more leak-proof adjuster system were implemented. In turn, this saves additional effort for the engine design. The T branch is not necessary in the design of central valve 9. This dispenses with, for example, a large number of boreholes on the piston head (valve slide). It is sufficient to provide a fairly small opening/borehole in order to vent the clearance space behind the piston. At the same time, the third and fourth control windows are dispensed with. Two control edges on the piston and two control edges on the housing are no longer required. This in turn saves on costs in manufacturing the individual parts.

LIST OF REFERENCE NUMERALS

[0042] 1 camshaft adjuster [0043] 2 stator [0044] 3 working chamber [0045] 4 first subchamber [0046] 5 second subchamber [0047] 6 rotor [0048] 7 vane [0049] 8 rotation axis [0050] 9 central valve [0051] 10 first hydraulic line [0052] 11 second hydraulic line [0053] 12 third hydraulic line [0054] 13 supply line [0055] 14 first check valve device [0056] 15 second check valve device [0057] 16 piston [0058] 17 third check valve device [0059] 18 first line portion [0060] 19 second line portion [0061] 20 first sheet metal section [0062] 21 second sheet metal section [0063] 22 cavity [0064] 23 camshaft [0065] 24 first reference arrow [0066] 25 second reference arrow [0067] 26 third reference arrow [0068] 27 fourth reference arrow