Camshaft adjuster

Abstract

A camshaft adjuster including a stator, a rotor and a pressure medium supply, at least one chamber being formed on the stator, which is divided into two working chambers by at least one vane formed on the rotor or rotatably fixedly connected to the rotor is provided. A pressure medium is applicable to each of the two working chambers via the pressure medium supply in such a way that a pressure of the pressure medium may be increased in each of the working chambers to the extent that the pressure increase results in a rotation of the rotor. A switchable valve is formed in the vane of the rotor, which, in a first switching position of the valve, allows a flow of the pressure medium from a first working chamber through the vane into a second working chamber, in a second switching position the valve hydraulically separating the working chambers from each other. A locking element, which fixes the vane in a defined position with respect to the chamber, is designed to control an inflow or outflow of the pressure medium into or out of a working chamber. The pressure medium supply includes an oil pump, a supply line connecting the oil pump to at least one of the working chambers and a hydraulic accumulator, which differs from the oil pump and the supply line.

Claims

1. A camshaft adjuster comprising: a stator; a rotor; a pressure medium supply; at least one chamber being formed on the stator, the at least one chamber being divided into two working chambers by at least one vane formed on the rotor or rotatably fixedly connected to the rotor; a pressure medium being applicable to each of the two working chambers via the pressure medium supply in such a way that a pressure of the pressure medium in a particular working chamber of the two working chambers is increasable so that a pressure increase results in a rotation of the rotor, the pressure medium supply including an oil pump, a supply line connecting the oil pump to at least one of the two working chambers, and a hydraulic accumulator different from the oil pump and the supply line; a switchable valve being formed in the rotor, the switchable valve, in a first switching position of the valve, permitting the pressure medium to flow from a first working chamber of the two working chambers, through the rotor and the switchable valve into a second working chamber of the two working chambers without passing through the oil pump and the hydraulic accumulator, the valve hydraulically separating the first and second working chambers from each other in a second switching position; and a locking element fixing the vane in a defined position with respect to the at least one chamber, the locking element being designed to control an inflow or an outflow of pressure medium into or out of one of the two working chambers.

2. The camshaft adjuster as recited in claim 1 wherein an oil supply of the at least one chamber from the hydraulic accumulator takes place in the second switching position of the valve.

3. The camshaft adjuster as recited in claim 1 wherein the pressure medium in the hydraulic accumulator is stored under a higher pressure with respect to an ambient pressure.

4. The camshaft adjuster as recited in claim 1 wherein, in the second switching position of the valve, the first working chamber is connected to the hydraulic accumulator in such a way that the first working chamber is filled from the hydraulic accumulator via a line in a first operating state.

5. The camshaft adjuster as recited in claim 1 wherein, in the second switching position of the valve, the second working chamber is connected to the hydraulic accumulator in such a way that the second working chamber is filled from the hydraulic accumulator in a second operating state.

6. The camshaft adjuster as recited in claim 1 wherein at least first and second chambers of the at least one chamber, are formed on the stator, the first chamber being divided into the first and second working chambers by a first vane of the at least one vane, and the second chamber being divided into third and fourth working chambers by a second vane of the at least one vane; the hydraulic accumulator being connected to the first and second chambers via a shared line, the shared line branching in such a way that a first branch of the line is connected to the first chamber by the valve, and a second branch of the line is connected to the second chamber by a further valve.

7. The camshaft adjuster as recited in claim 6 wherein the at least one chamber includes a third chamber.

8. The camshaft adjuster as recited in claim 6 wherein, in the second switching position of the valves, the first working chamber of the first chamber is hydraulically connected to the hydraulic accumulator, the pressure medium flowing out of the hydraulic accumulator into the first working chamber of the first chamber in a first operating state.

9. The camshaft adjuster as recited in claim 6 wherein, in the second switching position of the valve or a second switching position of the further valve, the fourth working chamber of the second chamber is connected to the hydraulic accumulator in such a way that the pressure medium flows out of the hydraulic accumulator into the fourth working chamber of the second chamber in a second operating state.

10. The camshaft adjuster as recited in claim 1 further comprising a check valve is situated in the rotor.

11. The camshaft adjuster as recited in claim 10 wherein the check valve is situated in the vane of the rotor.

12. The camshaft adjuster as recited in claim 1 further comprising a line between the hydraulic accumulator and the at least one chamber is situated in parallel to the supply line between the oil pump and the chambers.

13. The camshaft adjuster as recited in claim 1 wherein the switchable valve is formed in the vane of the rotor, the switchable valve in the first switching position of the valve permitting the pressure medium to flow from the first working chamber through the vane into the second working chamber.

14. A camshaft adjuster comprising: a stator; a rotor; a pressure medium supply; at least one chamber being formed on the stator, the at least one chamber being divided into two working chambers by at least one vane formed on the rotor or rotatably fixedly connected to the rotor; a pressure medium being applicable to each of the two working chambers via the pressure medium supply in such a way that a pressure of the pressure medium in a particular working chamber of the two working chambers is increasable so that a pressure increase results in a rotation of the rotor; a switchable valve being formed in the vane of the rotor, the switchable valve, in a first switching position of the valve, permitting the pressure medium to flow from a first working chamber of the two working chambers, through the rotor into a second working chamber of the two working chambers, the valve hydraulically separating the first and second working chambers from each other in a second switching position; and a locking element fixing the vane in a defined position with respect to the at least one chamber, the locking element being designed to control an inflow or an outflow of pressure medium into or out of one of the two working chambers; the pressure medium supply including an oil pump, a supply line connecting the oil pump to at least one of the two working chambers, and a hydraulic accumulator different from the oil pump and the supply line, wherein at least first and second chambers of the at least one chamber, are formed on the stator, the first chamber being divided into the first and second working chambers by a first vane of the at least one vane, and the second chamber being divided into third and fourth working chambers by a second vane of the at least one vane; the hydraulic accumulator being connected to the first and second chambers via a shared line, the shared line branching in such a way that a first branch of the line is connected to the first chamber by the valve, and a second branch of the line is connected to the second chamber by a further valve.

15. The camshaft adjuster as recited in claim 14 wherein the at least one chamber includes a third chamber.

16. The camshaft adjuster as recited in claim 14 wherein, in the second switching position of the valves, the first working chamber of the first chamber is hydraulically connected to the hydraulic accumulator, the pressure medium flowing out of the hydraulic accumulator into the first working chamber of the first chamber in a first operating state.

17. The camshaft adjuster as recited in claim 14 wherein, in the second switching position of the valve or a second switching position of the further valve, the fourth working chamber of the second chamber is connected to the hydraulic accumulator in such a way that the pressure medium flows out of the hydraulic accumulator into the fourth working chamber of the second chamber in a second operating state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained below on the basis of preferred specific embodiments with reference to the appended figures. In the figures, the same components or components having the same function are identified by the same reference numerals.

(2) FIG. 1 shows a schematic function representation of a hydraulic camshaft adjuster according to the present invention;

(3) FIG. 2 shows the schematic function representation of the hydraulic camshaft adjuster according to the present invention in a second switching position; and

(4) FIG. 3 shows the schematic function representation of the hydraulic camshaft adjuster according to the present invention in the second switching position in a different flow of the pressure medium.

DETAILED DESCRIPTION

(5) A camshaft adjuster 1 according to the present invention, including a stator 2 and a rotor 3, is illustrated in FIG. 1. Webs 17 are formed on stator 2, which divide an annular space between stator 2 and rotor 3 into chambers 5, 51, 52, 53. In principle, a rotor 3 having only one chamber 5 is possible, however three or more chambers 5, 51, 52, 53 are preferably formed on rotor 3, as illustrated in FIG. 1. Chambers 5, 51, 52, 53 between stator 2 and rotor 3 are each divided into two working chambers 6, 7 by a vane 4, 41, 42, 43 of rotor 3, particular working chambers 6 on the left of vane 4 of rotor 3 in the figures being referred to as first working chambers 6, 61, 62, and the working chambers on the right of vane 4 in the figures being referred to as second working chambers 7, 71, 72. Switchable valves 8, 81, 82 are formed in each of vanes 4, 41, 42, 43 of rotor 3, valves 8, 81, 82 each being adjustable between at least two switching positions. In a first switching position of valves 8, 81, 82, working chambers 6, 61, 62, 7, 71, 72 are each hydraulically short-circuited, the pressure medium being able to flow through valves 8, 81, 82 or via one of locking elements 9 in vanes 4, 41, 42, 43 for the purpose of pressure compensation.

(6) Camshaft adjuster 1 according to the present invention furthermore includes a pressure medium supply 10, which includes an oil pump 11, a supply line 12 and a hydraulic accumulator 13, which differs from oil pump 11 and supply line 12. When valves 8, 81, 82 are in the first switching position, supply line 12 may be connected to either working chambers 6, 61, 62 or working chambers 7, 71, 72. The connection to working chambers 7, 71, 72 is illustrated. Hydraulic accumulator 13 may be supplied with pressure medium via oil pump 11. Alternatively or additionally, it is provided that hydraulic accumulator 13 is filled with pressure medium flowing out of working chambers 6, 61, 62, 7, 71, 72 of camshaft adjuster 1 or with leakage oil. Hydraulic accumulator 13 is designed in a simple structure as a pressure medium reservoir, which is under ambient pressure. Alternatively, however, it is also conceivable that hydraulic accumulator 13 stores the pressure medium at a pressure which is higher than the ambient pressure to thereby facilitate a faster pressure medium supply of working chambers 6, 61, 62, 7, 71, 72. Hydraulic accumulator 13 may be integrated into the housing of camshaft adjuster 1 or be designed as a separate element. In the first switching position of valves 8, 81, 82, working chambers 6, 61, 62, 7, 71, 72 are separated from hydraulic accumulator 13, so that, in this switching position, hydraulic accumulator 13 does not influence the function of the hydraulic free flow between working chambers 6, 61, 62, 7, 71, 72. The connections between working chambers 6, 61, 7, 72 and hydraulic accumulator 13 may be opened and closed via valves 8, 81, 82.

(7) Camshaft adjuster 1 from FIG. 1 is illustrated in a second switching position in FIG. 2. The design is basically identical, and only the differences are discussed below. Hydraulic accumulator 13 is connected to chambers 5, 51, 52 of camshaft adjuster 1 via a line 14, a first branch 15 of line 14 including first chamber 51 being connected to valve 81 on a side facing second working chamber 71 of first chamber 51, and a second branch 16 of line 14 including second chamber 52 being connected to valve 82 on a side facing first working chamber 62. An adjustment of rotor 3 in the advance direction induces an enlargement of particular first working chambers 6, 61, 62 and a reduction in the size of particular second working chambers 7, 71, 72. The pressure in first working chambers 6, 61, 62 is increased in such a way that a rotation of rotor 3 in the desired direction takes place due to the pressure. By adjusting valves 8, 81, 82 into a second switching position, working chambers 61 and 72 are now connected to hydraulic accumulator 13 via branches 15, 16 of line 14. Due to the oscillating torques acting upon the camshaft and/or due to an activation of pressure medium supply 10 via a central valve, which is not illustrated, camshaft adjuster 1 is adjusted in the advance direction. First working chambers 6, 61, 62 increase in size, so that an underpressure is able to form in particular working chambers 6, 61, 62 if insufficient pressure medium is supplied. Due to the pressure difference between hydraulic accumulator 13 and working chamber 61, pressure medium flows out of hydraulic accumulator 13 into working chamber 61 via line 14, in particular via first branch 15 of line 14, and valve 81. This prevents air from being sucked in by oil pump 11 if working chamber 61 is insufficiently supplied, which impairs the functionality of camshaft adjuster 1. To prevent pressure medium from flowing out of working chambers 6, 61, 62, 7, 71, 72, a check valve 18 is situated in particular vanes 4, 41, 42 of rotor 3. Check valve 18 in vane 42 prevents the pressure medium from flowing back out of working chamber 72, while check valve 18 in vane 41 is opened, due to the pressure difference between hydraulic accumulator 13 and working chamber 61, and enables the pressure medium to flow into working chamber 61.

(8) FIG. 3 shows camshaft adjuster 1 from FIG. 1 in a second switching position and in another operating state, which differs from the operating state illustrated in FIG. 2. If camshaft adjuster 1 is adjusted in the retard direction, the volume of second working chambers 7, 71, 72 is increased, and the volume of first working chambers 6, 61, 62 is reduced, so that pressure medium must be supplied to second working chambers 7, 71, 72. In an adjustment in the retard direction, pressure medium flows out of hydraulic accumulator 13 into working chamber 72 via second branch 16 of line 14 and through valve 82, while working chambers 7, 71, which are increasing in size in parallel, are filled by oil pump 11 and supply line 12.

LIST OF REFERENCE NUMERALS

(9) 1 camshaft adjuster 2 stator 3 rotor 4 vane 5 chamber 6 first working chamber 7 second working chamber 8 valve 9 locking element 10 pressure medium supply 11 oil pump 12 supply line 13 hydraulic accumulator 14 line 15 first branch 16 second branch 17 web 18 check valve 41 first vane 42 second vane 51 first chamber 52 second chamber 53 third chamber 61 first working chamber 62 first working chamber 71 second working chamber 72 second working chamber 81 first valve 82 second valve