Camshaft adjuster

Abstract

A camshaft adjuster has multiple locking guide slots and multiple locking pins spring-loaded in the direction of engagement with the locking guide slots and which, by varying assignment to the rotor and to the stator, are arranged relative to one another such that the rotor can, under the action of fluctuating torques, be automatically locked into the predetermined center position relative to the stator proceeding from a first early or late stop position by a successive engagement of the locking pins into the locking guide slots. The locking pins and the locking guide slots are arranged so that, in the event of a rotation of the rotor in the direction of the center locking position proceeding from the respective other second early or late stop position, the locking pins lock into the locking guide slots in the reverse sequence from different directions.

Claims

1. A camshaft adjuster comprising: a stator and a rotor, the rotor being rotation angle adjustable in the stator between an advance stop position and a retard stop position, the rotor being actuated with the aid of a pressure medium; a locking device for locking the rotor with respect to the stator in a predetermined central locking position between the advance and retard stop positions, the locking device including multiple locking gates and multiple locking pins each being spring-loaded in an engagement direction to a corresponding one of the locking gates and moved relative to each other during a rotation of the rotor with respect to the stator, due to a variable assignment to the rotor and the stator, and are situated with respect to each other in such a way that the rotor is lockable with respect to the stator by rotation of the rotor with respect to the stator when alternating torques act upon the camshaft, the rotor being lockable with respect to the stator from the advance stop position into the predetermined central locking position by the locking pins each engaging with the corresponding locking gate in a first successive order during a rotation of the rotor such that each locking pin locks with the corresponding locking gate at a different rotational position of the rotor with respect to the stator, and the rotor being lockable with respect to the stator from the retard stop position into the predetermined central locking position by the locking pins each locking in the corresponding locking gate in a second successive order that is reverse of the first successive order during a rotation of the rotor such that each locking pin locks in the corresponding locking gate at a different rotational position of the rotor with respect to the stator.

2. The camshaft adjuster as recited in claim 1 wherein the locking gates are situated and shaped in such a way that the locking gate in which a first of the locking pins first locks or is locked during a rotation from the one of the advance or retard stop position is also the locking gate in which a last of the locking pin locks during a rotation of the rotor from the other of the advance or retard stop position into the central locking position.

3. The camshaft adjuster as recited in claim 2 wherein the locking gate in which the first locking pin locks or is locked during a rotation of the rotor in a first direction from the advance or retard stop position is shaped in such a way that the first locking pin locked therein comes to stop against the edge of the locking gate when the central locking position is reached and prevents the rotor from continuing to rotate in the first direction.

4. The camshaft adjuster as recited in claim 3 wherein the locking gate in which the last locking pin locks or is locked during a rotation of the rotor from the advance or retard stop position is situated and shaped in such a way that the locking pin locked therein blocks a rotation of the rotor in a second direction counter to the first direction.

5. The camshaft adjuster as recited in claim 1 wherein the multiple locking gates include at least three locking gates and the multiple locking pins include at least three locking pins, each of the at least three locking gates being paired with one of the at least three locking pins, and the at least three locking gates are formed by curved, ring segment-shaped recesses or indentations, a first of the at least three locking pins locking in a first of the at least three locking gates and a second of the at least three locking pins locking in a second of the at least three locking gates during a rotation of the rotor from one of the advance or retard stop positions, a circumferential distance between the first and second locking gates being identical to a circumferential distance between the first and second locking pins.

6. The camshaft adjuster as recited in claim 1 wherein a first of the pins locks in a first of the locking gates and a second of the pins locks in a second of the locking gates during a rotation of the rotor from the advance or retard stop position, the first and second locking gates being axisymmetric to each other about a middle axis.

7. The camshaft adjuster as recited in claim 1 wherein a base surface of the locking gates has at least one step in at least one edge section.

8. The camshaft adjuster as recited in claim 7 wherein a width of the step in the circumferential direction corresponds to the rotation angle of the rotor around which the latter is rotated with respect to the stator until the next locking pin locks into the adjacent locking gate.

9. The camshaft adjuster as recited in claim 7 wherein the locking gates, in which one of the locking pins first locks or is locked during a rotation of the rotor from the advance or retard stop position have one or multiple steps only on the edge section of the base surface against which the locking pin rests in the advance or retard stop position.

10. The camshaft adjuster as recited in claim 1 wherein the locking gates, in which the engaging locking pins lock after the first locking pin is locked, have at least one step on both edge sections of the base surface facing the adjacent locking gates.

11. The camshaft adjuster as recited in claim 1 wherein the locking gate in which one of the locking pins is first locked in the advance stop position and the locking gate in which one of the locking pins is first locked in the retard stop position is shaped in the manner of a circular arc, and the length of the circular arc of the locking gates are dimensioned in such a way that the locking pins guided therein are movable from the advance or retard stop position into a central locking position in which rotor is locked with respect to stator in both directions of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is explained in greater detail below on the basis of one preferred exemplary embodiment. Specifically:

(2) FIGS. 1, 2 and 3 show a camshaft adjuster, including a rotor in different locking positions, starting from the retard stop position in the direction of rotation toward the central locking position;

(3) FIGS. 4, 5 and 6 show a camshaft adjuster, including a rotor in different locking positions, starting from the advance stop position in the direction of rotation toward the central locking position;

(4) FIG. 7 shows a camshaft adjuster, including a rotor which is locked in the central locking position; and

(5) FIG. 8 shows a sealing cover or the base surface of the stator, including multiple locking gates, and a sectional representation of a locking gate.

DETAILED DESCRIPTION

(6) A camshaft adjuster of an internal combustion engine according to the present invention, including a stator 1 and a rotor 2, is apparent in FIG. 1. Stator 1 has a cup-shaped design and is provided with a toothing 3 on its outside for the purpose of being driven by a crankshaft via a chain or toothed belt. Rotor 2 is connectable to a camshaft in the known manner, e.g., via a central screw, and is driven to a rotary motion with the aid of stator 1. Stator 1 furthermore includes a plurality of stator webs 20, 21, 22, and 23, including threaded bores 4 situated therein, which divide an annular space provided between stator 1 and rotor 2 into multiple pressure chambers I. Rotor 2 includes a plurality of vanes 14, 15, 16 and 17, which extend radially outwardly to the inner wall of stator 1 and divide each pressure chamber I into two working chambers A and B. A translucently represented sealing cover 5 is furthermore provided, which is screwed into threaded bores 4 of stator 1 with the aid of fastening screws and which includes four locking gates 6, 7, 8 and 9. Four locking pins 10, 11, 12, 13 are also provided in rotor 2, which are spring-loaded in the engagement direction of locking gates 6, 7, 8 and 9 and to which pressure medium may be applied via a common pressure medium channel 26 for the purpose of unlocking from locking gates 6, 7, 8 and 9. During operation of the internal combustion engine, pressure chambers I are filled with pressure medium at least after a certain start phase, whereby the rotary motion of stator 1 is transmitted to rotor 2.

(7) Locking gates 6, 7, 8 and 9 are ring segment-like or circular arc-shaped recesses or indentations in sealing cover 5, which are oriented and dimensioned in such a way that their center lines run on a common diameter.

(8) Upper left vane 14 in the illustration is designed to be wider than remaining vanes 15, 16 and 17 and is used as a stop for rotor 2 for the purpose of limiting the rotary motion of rotor 2 with respect to stator 1 in the advance and retard stop positions. In order for rotor 2 to rotate into the provided stop positions in a preferably controlled manner without it being blocked in its rotary motion, e.g., by existing production radii, recesses 18 and 19 are provided on vane 14 on its outer edge sides extending into the illustration plane. For the same reasons, recesses 24 and 25 are provided on the two stator webs 20 and 21, which delimit pressure chamber I in which vane 14 is situated, on the radially inner edge sides extending into the illustration plane.

(9) In the illustration in FIG. 1, rotor 2 is in the retard stop position, i.e., rotor 2 rests with vane 14 against the right side of stator web 20 delimiting pressure chamber I. In this position of rotor 2, working chamber A has the smallest volume and working chamber B to the right of vane 14 has the largest volume. In the event that the internal combustion engine is suddenly turned off in this position of rotor 2 or, e.g., if it suddenly shuts down due to stalling, problems may arise when the internal combustion engine is restarted, which are to be eliminated by the automatic reverse rotation of rotor 2, which is described below, into central locking position MVP apparent in FIG. 7. The alternating torques which act upon the camshaft when the camshaft adjuster is not yet completely filled with pressure medium, in connection with the design of locking gates 6, 7, 8 and 9, locking pins 10, 11, 12 and 13 proposed according to the present invention, are used for the automatic reverse rotation of rotor 2 into central locking position MVP as described below.

(10) In the retard stop position illustrated in FIG. 1, first locking pin 10 already engages with locking gate 6, while the other locking pins 11, 12 and 13 still rest against the side wall of sealing cover 5 outside locking gates 7, 8 and 9. It is important that first locking pin 10 engages with locking gate 6 in such a way that rotor 2 is able to rotate relative to stator 1 at least clockwise in the direction of central locking position MVP. In the event that a torque acts upon rotor 2 in the clockwise direction in this position of rotor 2, rotor 2 is rotated clockwise with respect to stator 1 into the position in FIG. 2, in which second locking pin 13 locks into adjacent locking gate 9. If a subsequent torque occurs in the opposite direction, rotor 2 can no longer rotate back into the retard stop position. The next time a torque oriented in the clockwise direction acts upon the camshaft and thus on rotor 2, the latter continues to be rotated in the clockwise direction into the position illustrated in FIG. 3, in which second locking pin 13 locks into locking gate 9. Locking pin 10 is also moved into locking gate 6, so that it no longer rests against the radially oriented edge section of locking gate 6. The reverse rotation of rotor 2 back to the retard stop position is blocked in this position of rotor 2 by locking pin 13, which rests against the radial edge section of locking gate 9. During another rotation of rotor 2, locking pin 12 finally locks into locking gate 8 (see FIG. 3) in a next step, and last locking pin 11 finally locks into locking gate 7 in the central locking position MVP illustrated in FIG. 7.

(11) In central locking position MVP illustrated in FIG. 7, locking pins 10 and 11 rest against the radial edge sections of locking gates 6 and 7, so that rotor 2 is locked with respect to stator 1 in both directions of rotation.

(12) The same camshaft adjuster having rotor 2 situated in the advance stop position is apparent in FIG. 4, in which rotor 2 rests with vane 14 against stator web 21, which delimits pressure chamber I on the other side. Locking pin 11 is already locked into locking gate 7. If the internal combustion engine is started with the aid of a rotor 2 in this position, rotor 2 is gradually rotated counterclockwise into the position shown in FIG. 5 and FIG. 6, based on the same principle of the active alternating torques, locking pins 12 and 13 consecutively locking until last locking pin 10 finally locks into locking gate 6, and rotor 2 is blocked with respect to stator 1 in central locking position MVP illustrated in FIG. 7. The automatic reverse rotation of rotor 2 from the advance and retard stop positions is based on the same principle, with the difference that, during a rotation of rotor 2 from the advance stop position, locking pins 10, 11, 12 and 13 lock into locking gates 6, 7, 8 and 9 in the reverse order and from different directions than during a reverse rotation of rotor 2 from the retard stop position. The automatic reverse rotation of rotor 2 is thus implemented using the same locking pins 10, 11, 12, 13 and locking gates 6, 7, 8 and 9, so that no additional costs arise compared to the approach known from the prior art.

(13) FIG. 8 shows two locking gates 6, 7, 8, 9 in which the first and second locking pins 10, 11, 12, 13 lock during a rotation of the rotor 2 from the advance or retard stop position are situated axisymmetrically to a middle axis X.

(14) Sealing cover 5, including locking gates 6, 7, 8 and 9, is apparent in FIG. 8. A sectional representation along section line F-F of locking gate 8 is shown in the illustration on the right. Locking gates 8 and 9, in which second or third locking pin 12 or 13 locks during a rotation of rotor 2 from the advance and retard stop positions, are each provided with steps 27 on their edge sections of the base surface oriented in the circumferential direction, while locking gates 6 and 7, into which first or last locking pin 10 or 11 locks, are provided with steps 27 only on their edge sections of the base surfaces facing each other. This is due to the fact that locking pins 10 and 11 always lock into locking gates 6 and 7 only from one side during the automatic reverse rotary motion, since one of locking pins 10 and 11 already engages with locking gate 6 or 7 in the advance and retard stop positions.

(15) Steps 27 each form stop surfaces in the manner of a grid pattern, against which locking pins 10, 11, 12 and 13 rest in the circumferential direction in the intermediate positions between the advance and retard stop positions and central locking position MVP. As a result, the reverse rotation of rotor 2 is blocked in the direction of the advance and retard stop positions, and a continued rotation of rotor 2 in the direction of central locking position MVP is simultaneously facilitated.

LIST OF REFERENCE NUMERALS

(16) 1 stator 2 rotor 3 toothing 4 threaded bore 5 sealing cover 6 locking gate 7 locking gate 8 locking gate 9 locking gate 10 locking pin 11 locking pin 12 locking pin 13 locking pin 14 vane 15 vane 16 vane 17 vane 18 recess 19 recess 20 stator web 21 stator web 22 stator web 23 stator web 24 recess 25 recess 26 pressure medium channel 27 step