Camshaft adjuster

Abstract

A camshaft adjuster including a drive element, a first output element and a second output element all having a plurality of vanes; the two output elements can be braced relative to one another in the peripheral direction using an expanding spring located between the output elements; only the first output element is designed in such a way as to be connectable to a camshaft; a locking mechanism can lock the two output elements together and unlock same such that the two output elements are jointly or separately rotatable relative to the drive element; a vane of the second output element is in contact with a vane of the drive element, and the expanding spring puts a vane of the first output element at a distance from the vane of the drive element, so the first output element is in an angular position relative to the drive element which lies within the angle adjustment range between the first output element and the drive element.

Claims

1. A hydraulic camshaft adjuster comprising: a drive element; a first output element; and a second output element, the drive element and the first and second output elements each including multiple vanes, the first and second output elements bracing against one another in a circumferential direction via an expanding spring situated between the first and second output elements, only the first output element being configured to connect to a camshaft, and a locking mechanism for locking or unlocking the first and second output elements with respect to one another so that the first and second output elements rotate either jointly or separately relative to the drive element, a vane of the second output element contacting a vane of the drive element, and the expanding spring spacing a vane of the first output element apart from the vane of the drive element and the first output element thus being in an angular position relative to the drive element within an angular adjustment range between the first output element and the drive element.

2. The camshaft adjuster as recited in claim 1 wherein in a locked state, a vane of the first output element at least partially overlaps a vane of the second output element, and together with a vane of the drive element form a shared working chamber acted on by hydraulic medium pressure for displacing both the first and second output elements relative to the drive element.

3. The camshaft adjuster as recited in claim 2 the working chamber is delimited in the circumferential direction by the vanes of the drive element and of the first output element, and is delimited in an axial direction by the vane of the second output element and a cover element connected in a rotatably fixed manner to the drive element.

4. The camshaft adjuster as recited in claim 2 wherein in the locked state, the first and second output elements rotate together relative to the drive element via the hydraulic medium pressure.

5. The camshaft adjuster as recited in claim 2 wherein the first output element includes a hydraulic medium channel communicating with the working chamber delimited by a contact of the vane of the drive element with the vane of the second output element.

6. The camshaft adjuster as recited in claim 1 wherein the locking mechanism includes a locking piston and a locking slot with a partially circumferential groove, and when the locking piston is engaged in the groove the first output element rotates with respect to the second output element in a direction of a contact of the vanes of the drive element and the second output element.

7. The camshaft adjuster as recited in claim 6 wherein the locking slot has a borehole situated within the partially circumferential groove, no relative rotation between the first and second output elements being possible when the locking piston is engaged in the borehole.

8. The camshaft adjuster as recited in claim 6 wherein the locking slot is formed by the second output element, and the locking piston is accommodated by the first output element.

9. The camshaft adjuster as recited in claim 1 wherein the camshaft adjuster includes a second spring bracing the first output element or the second output element with respect to the drive element.

10. The camshaft adjuster as recited in claim 1 wherein the first and second output elements each have a depression which accommodates an expanding spring designed as a coil spring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Exemplary embodiments of the present invention are illustrated in the figures.

(2) FIG. 1 shows a camshaft adjuster according to the present invention in a section along its rotational axis;

(3) FIG. 2 shows a cross section of the camshaft adjuster according to FIG. 1 in a base position of the first output element;

(4) FIG. 3 shows a cross section of the camshaft adjuster according to FIG. 1 in a first end stop position of the first output element;

(5) FIG. 4 shows a cross section of the camshaft adjuster according to FIG. 1 in the center position; and

(6) FIG. 5 shows a cross section of the camshaft adjuster according to FIG. 1 in a second end stop position of the first output element.

DETAILED DESCRIPTION

(7) FIG. 1 shows a camshaft adjuster 1 according to the present invention in a section along its rotational axis 19. The section follows section line F-F in the figures described below. Camshaft adjuster 1 includes a first output element 3a, a second output element 3b, and a drive element 2. The two output elements 3a and 3b rest flatly with their end faces against one another, and are situated in succession along rotational axis 19. First output element 3a is situated on the side of camshaft adjuster 1 facing the camshaft, and is connected or designed to be connectable to the camshaft, not illustrated here. Second output element 3b is situated on the side of camshaft adjuster 1 facing away from the camshaft. Both output elements 3a and 3b are initially interlocked with one another in the circumferential direction 8, as discussed below with reference to the further figures.

(8) Camshaft adjuster 1 is axially delimited on the one hand by a cover element 10 which is situated on the side facing the camshaft and connected in a rotatably fixed manner to drive element 2, and which rests in a sealing manner against first output element 3a, and on the other hand by a sealing front cover 20 which is situated on the side of camshaft adjuster 1 facing away from the camshaft and likewise connected in a rotatably fixed manner to drive element 2. On their mutually facing end faces, output elements 3a and 3b each have a depression 16 in which an expanding spring 7 is accommodated. Expanding spring 7 presses the two output elements 3a and 3b apart in circumferential direction 8, so that vanes 5 and 6 of output elements 3a and 3b, respectively, overlap only partially in the axial direction, and the pressure surfaces of vanes 5 and 6, which are acted on by pressure from pressure oil in working chambers A, B, are spaced apart from one another in circumferential direction 8.

(9) Output element 3a has a borehole 21 which is aligned with borehole 14 in locking slot 12, and which accommodates locking piston 11, a cartridge 18, and a locking spring 17 of locking mechanism 9. Locking spring 17, which is designed as a compression spring, presses locking piston 11 into locking slot 12, provided that no oil pressure is present at locking piston 11. Due to the overlap of locking piston 11 with borehole 21 and borehole 14, both output elements 3a and 3b are rotatably fixed with respect to one another. Locking spring 17 is supported on the one hand on a cartridge 18 situated in borehole 21 in first output element 3a, and on the other hand on locking piston 11. Locking piston 11 strikes against front cover 20 in the axial direction. Cartridge 18 strikes against cover element 10 in the axial direction. Locking slot 12 is formed by second output element 3b, and includes borehole 21 and a groove 13 which extends in the circumferential direction. Borehole 21 is situated within groove 13. Since locking piston 11 is not completely countersinkable in borehole 21, and therefore is not engaged with locking slot 12, uncontrolled twisting between the two output elements 3a and 3b is prevented, thus also ensuring that working chambers A and B maintain a pressure-tight design, and vanes 5 and 6 are not spread wide enough apart that a hydraulic short circuit may occur between working chambers A and B.

(10) FIG. 2 shows a cross section of camshaft adjuster 1 according to FIG. 1 in a base position of first output element 3a. The first quadrant is considered for explaining the mode of functioning of the mechanism. Clearly, vanes 4, 5, 6, working chambers A, B, and the pressure medium supply channels are repeated in the circumferential direction in the other quadrants.

(11) Vane 6, designed as one part with second output element 3b, is in contact with vane 4, designed as one part, of drive element 2. Expanding spring 7 interlocks first output element 3a with second output element 3b in such a way that vane 5 of first output element 3a partially overlaps vane 6 and delimits a working chamber A in circumferential direction 8. Working chamber A is delimited in the axial direction by vane 6 of second output element 3b and front cover 20 on the side facing away from the camshaft, and by cover element 10 on the side facing the camshaft.

(12) The contour of groove 13 in locking slot 12 which is formed in a stepped manner by groove 13 and borehole 14 is clearly apparent. Locking piston 11 is engaged with borehole 14. Due to the contact between vanes 4 and 6, engaged locking piston 11 prevents an adjustment that would result in a reduction in the size of working chamber A. An adjustment that would result in a reduction in the size of working chamber B may take place by supplying pressure medium (pressure oil) via hydraulic medium channel a. Working chamber A may be filled and pressurized, and both output elements 3a and 3b may move in the clockwise direction without locking piston 11 becoming disengaged from borehole 14. Hydraulic medium channel a may hereby advantageously introduce pressure oil virtually free of coverings of its opening into working chamber A.

(13) FIG. 3 shows a cross section of camshaft adjuster 1 according to FIG. 1 in a first end stop position of first output element 3a.

(14) When pressure oil is supplied to locking piston 11, the locking piston moves out of borehole 14 until its front side is aligned with the base of groove 13. Working chamber A may now be reduced in size by pressurizing working chamber B and/or due to the camshaft frictional torque and vane 5 may be moved toward vane 4 until the two vanes contact one another and form the first end stop position. The first end stop position of first output element 3a may be formed by the contact of vanes 5 and 6 of the two output elements 3a and 3b together with vane 4 of drive element 2, or by groove 13.

(15) Locking piston 11 moves within groove 13 during this adjustment process. Groove 13 may form the first end stop position, in which the adjustment range made possible by groove 13 is selected to be smaller than the possible adjustment range between vanes 4 and 6. In this case, locking piston 11 strikes against the end of groove 13 before vanes 4 and 6 contact one another.

(16) The expanding spring is tensioned during this operation, so that first output element 3a may arrive back at the base position when the oil pressure in working chamber B falls away. In the process, locking piston 11 is guided in groove 13 and aligns the groove with borehole 14 and may engage in same, or strikes against the other end of groove 13.

(17) FIG. 4 shows a cross section of camshaft adjuster 1 according to FIG. 1 in the center position of first output element 3a.

(18) In this angular position of first output element 3a, although the volumes of working chambers A and B are not equal, vane 5 of first output element 3a in each case has virtually the same spacing in each case from vanes 4 in circumferential direction 8. Accordingly, vane 5 would cover virtually the same path (angle) to the first or second end stop position in the clockwise direction or in the counterclockwise direction. In this state of camshaft adjuster 1, expanding spring 7 has the same pretension as in FIG. 2. Locking mechanism 9 likewise remains locked, as in the state in FIG. 2.

(19) FIG. 5 shows a cross section of camshaft adjuster 1 according to FIG. 1 in a second end stop position of first output element 3a.

(20) The configuration of camshaft adjuster 1 largely corresponds to that from FIGS. 2 and 4. However, vane 5 of first output element 3a now has contact with vane 4 of drive element 2, successively situated in the circumferential direction, from FIG. 3. Vane 6 of second output element 3b is now spaced apart from this vane 4 in FIG. 5 in circumferential direction 8. Thus, working chamber B is delimited by vanes 6 and 4 in circumferential direction 8, and in the axial direction on the side facing the camshaft is delimited by vane 5 and cover element 10, and on the side facing away from the camshaft is delimited by front cover 20, which has a sealing design. Due to the spacing of vane 6 from vane 4 and the resulting connected design of working chamber B, working chamber B may easily be filled with pressure oil. A hydraulic medium channel may hereby advantageously introduce a pressure oil virtually free of coverings of its opening into working chamber B.

LIST OF REFERENCE SYMBOLS

(21) 1 camshaft adjuster 2 drive element 3a first output element 3b second output element 4 vane 5 vane 6 vane 7 expanding spring 8 circumferential direction 9 locking mechanism 10 cover element 11 locking piston 12 locking slot 13 groove 14 borehole 15 16 depression a hydraulic medium channel A working chamber B working chamber 17 locking spring 18 cartridge 19 rotational axis 20 front cover