Abstract
A camshaft adjusting device, including a vane cell adjuster having a stator connectable to a crankshaft and a rotor, which is rotatably supported in the stator and connectable to a camshaft. Webs on the stator, divide an annular space between the stator and the rotor into pressure chambers, wherein the rotor has a rotor hub and vanes extending radially outward from the rotor hub, which vanes divide the pressure chambers into two groups of working chambers having a different acting direction, into each of which working chambers pressure medium flowing in or out in a pressure-medium circuit can be admitted, and a central locking device for locking the rotor in relation to the stator. The central locking device has two spring-loaded locking pins in an accommodating space, and lockable in a locking slot secured to the stator and lock in the locking slot when the rotor rotates from the direction of an early or late stop position into the locking position from different directions, wherein the locking pin forms a valve device together with the particular accommodating space, wherein the locking pin is a step pin.
Claims
1. A camshaft adjusting device comprising: a vane cell adjuster including a stator connectable to a crankshaft of an internal combustion engine; and a rotor rotatably mounted in the stator connectable to a camshaft, multiple webs being provided on the stator, the multiple webs subdividing an annular space between the stator and the rotor into a plurality of pressure chambers, the rotor including a rotor hub and a plurality of vanes extending radially outwardly from the rotor hub, the plurality of vanes subdividing the plurality of pressure chambers into two groups of working chambers having a different operating direction, each of which may be acted upon by pressure medium flowing into or out of a pressure medium circuit, and a central locking device for locking the rotor in at least one locking position relative to the stator, the central locking device including at least two spring-loaded locking pins lockable in a locking slot secured to the stator in an accommodating space, the at least two spring-loaded locking pins locking in the locking slot when the rotor rotates from a direction of an early or late stop position into the at least one locking position from different directions, one of the at least two spring-loaded locking pins together with the accommodating space forming a valve device, the one of the at least two spring-loaded locking pins forming a valve pin, and the valve pin being a stepped pin, the valve device being fluidically connectable to a respective one of the working chambers via a first or a second outflow pressure medium line, an inflow pressure medium line being connected only to the second outflow pressure medium line in a first switching position of the valve device, and the first outflow pressure medium line and the second outflow pressure medium line being fluidically connected to the inflow pressure medium line in a second switching position.
2. The camshaft adjusting device as recited in claim 1 wherein in a first switching position of the valve device, the inflow pressure medium line is fluidically connected to the respective one of the working chambers exclusively via at least one check valve, and the valve device in a second switching position free flowingly connects at least one inflow pressure medium line to a respective one of the plurality of pressure chambers.
3. The camshaft adjusting device as recited in claim 2 wherein the check valve is situated in such a way that a flow through the check valve is possible only in the case of a through-flow from the inflow pressure medium line in the direction of the respective one of the plurality of pressure chambers.
4. The camshaft adjusting device as recited in claim 2 wherein the check valve is formed by a band check valve.
5. The camshaft adjusting device as recited in claim 4 wherein the band check valve is situated on the valve pin.
6. The camshaft adjusting device as recited in claim 4 wherein the band check valve in the first and in the second switching position is fluidically connected to the inflow pressure medium line and to the second outflow pressure medium line.
7. The camshaft adjusting device as recited in claim 4 wherein a band of the band check valve is pre-stressed radially outwardly.
8. The camshaft adjusting device as recited in claim 1 wherein a check valve is provided in the second outflow pressure medium line.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The present invention is described in greater detail below with reference to a preferred exemplary embodiment. In the individual figures, in particular:
(2) FIG. 1 schematically shows a representation of a camshaft adjusting device according to the present invention with a circuit diagram of a pressure medium circuit during an adjusting movement of the rotor from the direction late into the center locking position;
(3) FIG. 2 shows a sectional representation of a camshaft adjusting device, from which the arrangement of the valve device in the rotor and the course of the pressure medium lines is discernible;
(4) FIG. 3 shows a first specific embodiment of a valve device including a band check valve;
(5) FIG. 4 shows a valve pin including a band of a check valve;
(6) FIG. 5 shows a band of a check valve;
(7) FIG. 6 shows a second specific embodiment of the present invention including a check valve in the second outflow pressure medium line;
(8) FIG. 7 shows a third specific embodiment of the present invention including a check valve in the second outflow pressure medium line.
DETAILED DESCRIPTION
(9) A camshaft adjusting device is apparent in FIG. 1, having a known basic construction with a schematically depicted vane cell adjuster as the basic component, which includes a stator 16 drivable by a crankshaft not depicted and a rotor 17 rotatably fixedly connectable to a camshaft also not depicted having multiple vanes 11 and 12 extending radially outwardly therefrom. In the upper development drawing, the vane cell adjuster is apparent, whereas a detail of rotor 17 having a center locking device 26 is apparent at the bottom left and a switching device in the form of a selector switch valve 7 for controlling the pressure medium flow is apparent at the bottom right. Selector switch valve 7 includes an A-port, B-port and C-port, to which pressure medium lines 18, 27 and 28 are fluidically attached. In addition, selector switch valve 7 is fluidically connected to a pressure medium reservoir T and to a pressure medium pump P which, during an actuation of the camshaft adjusting device, conveys the pressure medium, once it is returned, again from pressure medium reservoir T in a pressure medium circuit.
(10) A pressure medium circuit is also apparent having a plurality of pressure medium lines 1, 3, 4, 6, 8, 13, 14, 14a, 14b, 15, 18, 27, 28, 29, 31, 32, 34 and 42, which are selectively fluidically connectable to pressure medium pump P or pressure medium reservoir T via selector switch valve 7.
(11) Stator 16 includes a plurality of stator webs, which subdivide an annular space between stator 16 and rotor 17 into pressure chambers 24 and 25. Pressure chambers 24 and 25, in turn, are subdivided by vanes 11 and 12 of rotor 17 into working chambers 20, 21, 22 and 23, into which pressure medium lines 1, 3, 4 and 6 open. Center locking device 26 includes two locking pins 2 and 5, which are used for locking rotor 17 with respect to stator 16 in a locking slot 19 secured to the stator. Locking slot 19 may be situated in a sealing cover securely screwed to stator 16.
(12) In principle, the rotation angle of the camshaft relative to the crankshaft during normal operation is adjusted in the direction late, for example, by applying pressure medium to working chambers 21 and 23 and thereby increasing their volume, while at the same time forcing the pressure medium from working chambers 20 and 22 and reducing their volume. The stop position early is marked in the depictions with an F, and the stop position late is marked with an S. Working chambers 20, 21, 22 and 23, the volume of which is increased each time in groups during this adjusting movement, are referred to within the meaning of the present invention as working chambers 20, 21, 22 and 23 of one operating direction, while working chambers 20, 21, 22 and 23, the volume of which at the same time decreases, are referred to as working chambers 20, 21, 22 and 23 of the opposite operating direction. The volume change of working chambers 20, 21, 22 and 23 then result in rotor 17 with vanes 11 and 12 rotating with respect to stator 16. In the upper development drawing of stator 16, the volume of working chambers 21 and 23 is increased by an application of pressure medium via the B-port of selector switch valve 7, whereas the volume of working chambers 20 and 22 at the same time is reduced by the backflow of the pressure medium via the A-port of selector switch valve 7. This volume change results in a rotation of rotor 17 with respect to stator 16 from the direction early to late.
(13) A valve function pin 35 is also provided, which is also linearly displaceable and spring-loaded. Valve function pin 35 is spring-loaded in the direction of the engagement position in locking slots 19 and is situated in rotor 17 in such a way that it does not hinder the rotational movement of rotor 17 with respect to stator 16 in any position of rotor 17. Valve function pin 35 is moved practically only concurrently. To enable the adjustment of rotor 17 with respect to stator 16, center locking device 26 is first released by applying pressure medium via pressure medium pump P to locking slot 19 via pressure medium line 18 from the C-port of selector switch valve 7. Due to the application of pressure medium to locking slot 19, locking pins 2 and 5, as well as valve function pin 35, are forced out of locking slot 19, so that rotor 17 may subsequently rotate freely with respect to stator 16.
(14) In FIG. 1, it is apparent that a check valve 9 and 10, respectively, is situated in a rotor hub 30 of rotor 17 in spatial proximity to locking pins 2 and 5. However, this depiction is understood to be schematic, so that in an alternative specific embodiment, check valves 9 and 10 may also be situated in locking pins 2 and 5.
(15) Locking pins 2 and 5 are spring-loaded in the direction of a first switching position, in which they engage in locking slots 19 as is apparent based on locking pin 2 in FIG. 1. In this case, second outflow pressure medium line 8 is situated with check valve 9 situated therein in rotor hub 30 in such a way that in the first position of locking pin 2, it fluidically connects inflow pressure medium line 14 to second outflow pressure medium line 8 which, in turn, opens into working chamber 20 via first pressure medium line 1. Pressure medium line 27 is fluidically connected to pressure medium line 4 opening into working chamber 22 and, at the same time, opens into the A-port of selector valve 7. Check valve 9 is aligned in such a way that an inflow of the pressure medium into working chamber 20 is possible, whereas an outflow of pressure medium from working chamber 20 is prevented. Rotor 17 in this position is not locked once the internal combustion engine is turned off and is rotated in the direction of the stop position late, which may occur, for example, in the event of a stall of the internal combustion engine. Locking pin 5 does not engage in locking slot 19 and is shifted into a second switching position against the acting spring force, in which freely flowable first outflow pressure medium line 32 is fluidically connected by locking pin 5 in the second switching position to inflow pressure medium line 29. Pressure medium line 29 is fluidically connected to pressure medium line 6 and attached to the B-port of selector switch valve 7 via pressure medium line 28. To enable the free run and, therefore, the movement of the camshaft adjuster into the center locking position, working chambers 20 and 21 of pressure chamber 24, and working chambers 22 and 23 of pressure chamber 25 must be fluidically short-circuited. This occurs via valve function pin 35, which is moved from a first switching position into a second switching position as a result of the application of pressure medium on locking slot 19, and thereby fluidically connecting pressure medium line 15 to pressure medium line 34 via pressure medium line 42. This allows an overflow of the pressure medium between two oppositely functioning working chambers 20, 21, 22 and 23, which takes place as a function of the relative angle of stator 16 with respect to rotor 17 via a check valve 9 and 10 or via freely flowable pressure medium lines 13 and 32.
(16) During the start phase of the internal combustion engine, alternating torques act on the camshaft and, therefore, on rotor 17. The torques acting on rotor 17 in the direction of the arrow result in the pressure medium being forced out of working chambers 21 and 23 via pressure medium lines 3 and 6, see FIG. 1. With a movement of rotor 17 from the direction late into the center locking position, locking pin 5 is in the second switching position, as a result of which first outflow pressure medium line 32 is fluidically connected to inflow pressure medium line 29. In this way, the pressure medium may flow from pressure medium line 3 via pressure medium lines 32, 15, 42, 34, 27, 14, 8 and 1 into working chamber 20; thus, the flow takes place via check valve 9. In addition, the pressure medium may flow from working chamber 21 also via pressure medium lines 3, 32, 15, 42, 34, 27 and 4 into working chamber 22. The pressure medium from working chamber 23 flows via pressure medium lines 6, 29, 15, 42, 34, 27, and 4 into working chamber 22, and via pressure medium lines 6, 29, 15, 42, 34, 27, 14, 8 and 1 into working chamber 20; the flow in this case also takes place via check valve 9.
(17) Working chambers 20, 21, 22 and 23 are therefore short-circuited in the direction of the arrow in FIG. 1 when torques occur. In the event, however, that torques act counter to the direction of the arrow, the pressure medium is unable to exit working chamber 20 due to the alignment of check valve 9, rotor 17 being supported in this rotational direction via the pressure medium at check valve 9. A kind of free run is practically implemented as a result, by which rotor 17 is rotated automatically in pulses into the center locking position while utilizing the acting camshaft alternating torques, until locking pin 2 abuts the side of a stop of locking slot 19 and locking pin 5 is also locked in locking slot 19 supported by spring force.
(18) FIG. 2 shows a sectional representation of a camshaft adjusting device according to the present invention. A first valve device 36 is apparent, which is formed essentially by an accommodating space 43 and locking pin 2 guided therein. Locking pin 2 in this case forms a valve pin 40. Valve device 36 is situated in such a way that the axial movement of locking pin 2 occurs in the direction of the rotational axis of the camshaft adjusting device, the rotational axis of the camshaft adjusting device extending perpendicular to the drawing plane. First valve device 36 shown on the left side schematically represents the two possible switching positions, the flow of pressure medium in the first switching position occurring via check valve 9. It is schematically shown that in the second switching position of first valve device 36, pressure medium line 1 is fluidically freely connectable to pressure medium line 3 and 6, and in a first switching position, the fluidic connection between pressure medium line 1 and pressure medium line 3 and 6 is established via check valve 9. It is also apparent in FIG. 1 that working chambers 20 and 22, which have the same operating direction, are fluidically connectable to pressure medium pump P via selector switch valve 27.
(19) Specific embodiments for first valve device 36 are described below. These specific embodiments may be applied analogously to a second valve device 37, which is formed essentially by an accommodating space 44 and locking pin 5 mounted therein.
(20) FIG. 3 shows a specific embodiment of first valve device 36, in which check valve 9 is provided in locking pin 2. Valve pin 40 is formed by locking pin 2, valve pin 40 being a stepped pin. Valve pin 40 therefore includes two projections 38 and at least one annular groove 39. The adjoining inflow pressure medium line 14 and first and second outflow pressure medium lines 13 and 8 may be fluidically blocked with respect to accommodating space 43 via projections 38. A fluidic connection to accommodating space 43 is established between the adjoining inflow pressure medium line and first and second outflow pressure medium lines 13 and 8 by annular groove 39. Inflow pressure medium line 14 may be fluidically connected in various combinations to first and second outflow pressure medium lines 13 and 8 as a function of the position of valve pin 40, which thereby also determines the switching position of first valve device 36.
(21) In the specific embodiment from FIG. 3, check valve 9 is formed by a band check valve 46. Band check valve 46 in this case is situated in an annular groove 39 between two projections 38 of valve pin 40. One band 33 is preferably pre-stressed outwardly, i.e., in the case of a flow, band 33 is acted upon radially from the outside by pressure medium and compressed against the pre-stressing force, thereby unblocking a fluidic connection. In the case of a flow in the blocking direction, band 33 is acted upon radially from the inside by pressure medium and thus pressed against an inflow opening in such a way that this opening is fluidically blocked. This ensures that the pressure medium is able to flow from inflow pressure medium line 14 via band check valve 33 into second outflow pressure medium line 8; a backflow of the pressure medium from second outflow pressure medium line 8 into inflow pressure medium line 14 is prevented by band check valve 46. In an alternative specific embodiment, band 33 may also be pre-stressed radially inwardly.
(22) FIG. 4 shows valve pin 40 with band 33. It is apparent that two radii are provided at a transition between valve pin 40 and band 33. A homogeneous transition is thereby achieved between valve pin 40 and band 33. It is also apparent in FIG. 4 that band 33 is firmly connected to valve pin 40 so that in the case of an adjusting movement, valve pin 40 is moved concurrently.
(23) FIG. 5 shows a preferred geometry of band 33 having an enclosure of more than 360. The band check valve is essentially circular, a partial section 41 of band 33 protruding radially inwardly. In addition, alternative geometries for band 33 are also conceivable.
(24) The left image in FIG. 3 shows first valve device 36 in a second switching position, in which locking slot 19 is acted upon by pressure medium and valve pin 40 is therefore moved against the spring force. In the second switching position, a fluidic connection between inflow pressure medium line 14 and first outflow pressure medium line 13 is established by annular groove 39. A fluidic connection also exists between inflow pressure medium line 14 and second outflow pressure medium line 8. Thus, in the first switching position, the pressure medium may flow from inflow pressure medium line 14 into working chamber 20 via the two outflow pressure medium lines 13 and 8 fluidically connected in parallel. First valve device 36 is depicted on the right side of FIG. 3 in a first switching position. Locking slot 19 is de-pressurized, so that valve pin 40 is pushed by the spring force into the first switching position. In this position of valve pin 40, projection 38 blocks the fluidic connection between accommodating space 43 and first outflow pressure medium line 13. Despite the movement of valve pin 40 into the first switching position, a fluidic connection via band check valve 33 exists between inflow pressure medium line 14 and second outflow pressure medium line 8, i.e., the fluidic connection between inflow pressure medium line 14 and second outflow pressure medium line 8 is independent of the switching position. The axial extension of band check valve 46 is so great that inflow pressure medium line 14 and outflow pressure medium line 8 are connected in both switching positions. Also provided on band check valve 46 are flow openings 45, which are fluidically connected to outflow pressure medium line 8 regardless of the switching position of the valve pin. Flow openings 45 lead into the interior of band check valve 46, so that band 33 is acted upon radially from the inside by pressure medium when pressure medium flows from the direction of second outflow pressure medium line 8; a flow through the check valve is impossible from this direction. If the pressure medium flows from the direction of inflow pressure medium line 14, the band is then compressed and a fluidic connection to flow openings 45 is unblocked. At least one flow opening 45 is provided on band check valve 46, preferably, however, multiple flow openings 45 are provided radially on the outside lateral surface of band check valve 46. Flow openings 45 open into a circumferential annular channel 47, the axial extension of annular channel 48 being so great that the fluidic connection between flow opening 45 and outflow pressure medium line 8 is maintained regardless of the switching position. The fluidic connection between band check valve 46 and inflow pressure medium line 14 is likewise maintained regardless of the switching position of valve pin 40. First valve device 36 in this specific embodiment forms a 3/2-way valve. Alternatively, the specific embodiment with the band check valve 46 may also be implemented via a 4/2-way valve. For this purpose, inflow pressure medium 14 splits into two inflow pressure medium lines 14a and 14b upstream from accommodating space 43.
(25) A second specific embodiment of the present invention is shown in FIG. 6. Check valve 9 is situated here in second outflow pressure medium line 8. The left image in FIG. 6 shows valve pin 40 in a second switching position. Inflow pressure medium line 14 in this case is fluidically connected to first outflow pressure medium line 13; at the same time, inflow pressure medium line 14 is connected to second outflow pressure medium line 8, in which check valve 9 is situated. In the right image in FIG. 6, valve pin 40 is in the first switching position, as a result of which projection 38 blocks the fluidic connection between accommodating space 43 and first outflow pressure medium line 13. The fluidic connection between inflow pressure medium line 14 and second outflow pressure medium line 8 exists here as well. Thus, the valve device, as in the first exemplary embodiment in FIG. 3, is formed by a 3/2-way valve. However, check valve 9 in the specific embodiment from FIG. 8 is situated in second outflow pressure medium line 8. Check valve 9 is preferably a ball check valve. Alternatively, other check valves are also conceivable, however.
(26) FIG. 7 shows a third specific embodiment of the present invention, which differs from the second specific embodiment from FIG. 6 in that inflow pressure medium line 14 splits into two inflow pressure medium lines 14a and 14b before it opens into accommodating space 43; thus, a 4/2-way valve is formed. In the second switching position (see FIG. 7, left), inflow pressure medium line 14b is fluidically connected by groove 39 to first outflow pressure medium line 13. In this switching position, the fluidic connection between inflow pressure medium line 14a and second outflow pressure medium line 8 is blocked by projection 38. A fluidic connection exists in the first switching position (see FIG. 7, right) between inflow pressure medium line 14a and second outflow pressure medium line 8; the fluidic connection between inflow pressure medium line 14b and outflow pressure medium line 13 is fluidically blocked. In this exemplary embodiment, the fluidic connection between inflow pressure medium 14a and outflow pressure medium line 8, in which check valve 9 is situated, is a function of the switching position of valve pin 40.
LIST OF REFERENCE NUMERALS
(27) 1 pressure medium line 2 locking pin 3 pressure medium line 4 pressure medium line 5 locking pin 6 pressure medium line 7 selector switch valve 8 second outflow pressure medium line 9 check valve 10 check valve 11 vane 12 vane 13 first outflow pressure medium line 14 inflow pressure medium line 14a inflow pressure medium line 14b inflow pressure medium line 15 pressure medium line 16 stator 17 rotor 18 pressure medium line 19 locking slot 20 working chamber 21 working chamber 22 working chamber 23 working chamber 24 pressure chamber 25 pressure chamber 26 center locking device 27 pressure medium line 28 pressure medium line 29 inflow pressure medium line 30 rotor hub 31 first outflow pressure medium line 32 second outflow pressure medium line 33 band 34 pressure medium line 35 valve function pin 36 first valve device 37 second valve device 38 projection 39 groove 40 valve pin 41 partial section 42 pressure medium line 43 accommodating space 44 accommodating space 45 flow opening 46 band check valve 47 annular channel
