EP1302630B1 - Device for changing the timing of gas exchange valves of an internal combustion engine, especially a rotary piston phasing device for changing the angle of a camshaft relative to a crank shaft - Google Patents

Description

Name of the invention

Device for changing the timing of gas exchange valves of an internal combustion engine, in particular rotary piston adjusting device for adjusting the rotational angle of a camshaft relative to a crankshaft

description Field of the invention

The invention relates to a device for changing the timing of gas exchange valves of an internal combustion engine according to the preamble of forming features of claim 1, and it is particularly advantageous to rotary piston adjustment for rotational angle adjustment of a camshaft relative to a crankshaft realized.

Background of the invention

From the DE 196 23 818 A1 is a generic type valve timing control device known, which is attached to the drive end of a cylinder head mounted in an internal combustion engine camshaft and formed in principle as a function of various operating parameters of the internal combustion engine controllable hydraulic actuator. This device consists essentially of a standing with a crankshaft of the internal combustion engine in drive connection drive wheel and a rotatably connected to a camshaft the internal combustion engine associated impeller, which are in drive connection with each other and transmit the torque of the crankshaft to the camshaft of the internal combustion engine. In a preferred embodiment, the drive wheel has a hollow space formed by a hollow cylindrical peripheral wall and two side walls, in which two hydraulic working spaces are formed by two radial boundary walls extending to the longitudinal central axis of the device. Accordingly, the impeller has at the periphery of its hub two radially extending into the working space wings, which divide the working spaces in each case an A-pressure chamber and a B-pressure chamber, which in case of selective or simultaneous pressurization with a hydraulic pressure means pivotal movement or fixation of the impeller relative to the drive wheel and thus cause the camshaft relative to the crankshaft. In addition, the impeller when falling below a required for adjustment pressure fluid pressure, such as when switching off the engine by a separate locking element in a preferred base position within its adjustment range with the drive wheel mechanically coupled to, in particular when restarting the internal combustion engine to build up the required pressure medium pressure From the alternating torques of the camshaft resulting stop clatter of the impeller to avoid the boundary walls of the drive wheel. This, specifically designed as a stepped cylindrical locking pin locking element is arranged in a direction parallel to the longitudinal center axis of the device bore at the end of a blade of the impeller and displaceable by a spring element into a locking position within a receptacle in the camshaft side facing away from the drive wheel. In this case, the formed with a larger diameter portion of the locking pin is formed by the inner wall of the bore in the wing and the formed with a smaller diameter portion of the locking pin, the locking side for exact position determination between the impeller and drive wheel is additionally conical, through an inserted into the bore guide bushing guided. The inclusion of the locking pin is concretely incorporated as in the camshaft side facing away from the drive wheel elongated bore is formed, which extends in a direction transverse to the direction of rotation of the impeller and is connected via a groove with an A-pressure chamber of the device. In addition, the annular surface formed at the transition between the cylindrical portions of the locking pin is also connected via a radial bore to a B pressure chamber of the device so that both upon pressurization of the A pressure chambers of the device and upon pressurization of the B pressure chambers of the device, the locking pin is hydraulically actuated can be moved into a Entkoppelstellung within the bore in the wing of the impeller.

A disadvantage of this known device, however, is that the arrangement of the locking pin in a hole at the end of a wing of the impeller requires a massive construction of the wing and thus limits the number of possible hydraulic working spaces in the device to a maximum of three to four when with Device a conventional adjustment angle of about 30 ° NW should be feasible. In addition, the relatively large distance between the longitudinal axis of the bore in the impeller blade and the longitudinal center axis of the device is the cause that reduces the stiffness of the locked connection between the impeller and the drive wheel and that the locking pin is still subject to significant centrifugal forces in the engine operation related with the simultaneously increasing sensitivity to dirt of the lock by the rotationally attached at the end of the wings accumulating dirt particles in the hydraulic pressure medium, the function of the lock can adversely affect. Likewise, the embodiment of the lock with a stepped cylindrical locking pin, which is connected to the annular surface formed between the cylindrical sections and with its locking-side annular surface to both the A-pressure chambers and the B-pressure chambers of the device, has proven to be disadvantageous, that a lock when stopping the engine is not possible because at least one of the two surfaces is still acted on the locking pin with the pressure of the pressure medium and thus holds the locking pin in its Entkoppelstellung in the bore in the wing of the impeller. As a result, the device is not operable with a targeted locking and above all unsuitable for applications on SOHC engines or exhaust camshafts, in which a locking of the impeller or the camshaft in an "early" timing of the gas exchange valves of the internal combustion engine is necessary. The locking side conical design of the locking pin with a constant cone angle has also in connection with its elongated receiving bore in the camshaft side facing away from the drive wheel has the disadvantage that in the locking high component loads on the impeller and the drive wheel of the device occur and that there is a danger in the unlocking in that there is a jamming of the locking pin in the receiving bore. In addition, the increased space requirement and the relatively high production cost of the stepped locking pin is still to be mentioned as a disadvantage, since these are the cause of a limited applicability of the device in confined spaces in the engine compartment and relatively high production costs of the device.

From the DE 199 29 393 A1 another valve timing control device is known. Here, the mechanical coupling is effected by a pin-like locking element movably arranged in an axial bore in the wheel hub of the impeller, which is movable by a spring element into a coupling position within a complementary receptacle in the side wall of the drive wheel. The complementary recording of the locking element is disposed within the pressure medium guide to a volume-minimized A-pressure chamber of a hydraulic working space of the device, so that at the same time the recording of the locking element is pressurized at the start of the internal combustion engine by the pressurization of the A-pressure chambers of the hydraulic working chambers and this against the force its spring element hydraulically moved into its Entkoppelstellung in the axial bore in the wheel hub of the impeller.

Object of the invention

The invention is therefore based on the object to design a device for changing the timing of gas exchange valves of an internal combustion engine, in particular rotary piston adjustment for rotational angle adjustment of a camshaft relative to a crankshaft, which between its impeller and its drive wheel a simple and inexpensive to produce lock with a has low space requirements, which is largely unaffected by centrifugal forces and insensitive to dirt and which is arranged or designed so that the locked connection between impeller and drive wheel has a high rigidity and that universal use of the device is also possible on SOHC engines or exhaust camshafts ,

Summary of the invention

In a first embodiment of the device according to the preamble of claim 1, the object is achieved in that the inclusion of the locking element in one of the side walls of the drive wheel has a quadrangular and formed in its surface by a defined all-sided game greater than the cross-sectional area of the locking element contour and is formed with an opening worm groove for supplying pressure medium, which is connected exclusively to a pressure-free in the locking position of the impeller A-pressure chamber of the device and via which the recording of the locking element can be acted upon only by pressurization of the A-pressure chambers with the pressure of the hydraulic pressure medium.

In a further embodiment of the device according to the preamble of claim 1, the object is achieved in that the locking element is formed with a chamfer and a rounding of its front edge and a hollow end, while in its rear end face a blind hole for fixing the an end of the preferably designed as a compression coil spring spring element whose other end is supported on an inserted into the axial bore and formed with a centering counter-holder with a Y-shaped profile cross-section, in which the longitudinal grooves formed between its profile legs are also provided for pressure fluid venting the axial bore.

In a further embodiment of the device according to the preamble of claim 1, the object is achieved in that the receptacle of the locking element is preferably incorporated in the camshaft side facing away from the drive wheel and positioned so that their square-shaped contour with mounted device below the radial end of one of the boundary walls the drive wheel is arranged, wherein its preferably with a quarter-circle course extending to the level of the stop surface of an adjacent boundary wall of the drive wheel worm groove is arranged opening from a lying in the direction of rotation of the impeller in the contour of the recording.

According to the invention, this object is achieved in a device according to the preamble of claim 1 such that the locking element is formed as uniform over its entire length locking pin and disposed in an axial bore in the wheel hub of the impeller whose longitudinal axis has a minimum possible distance from the longitudinal central axis of the device ,

In an expedient development of the device according to the invention, the receptacle of the locking pin arranged in one of the sidewalls of the drive wheel has a quadrangular contour formed in its surface around a defined all-sided clearance greater than the cross-sectional area of the locking pin and is formed with an opening worm groove for supplying pressure medium is connected to a pressure-free in the locking position of the impeller A-pressure chamber of the device and thus causes the inclusion of the locking pin only when pressurized the pressure chambers of the device with the necessary for unlocking the locking pin pressure of the hydraulic pressure medium can be acted upon.

As an advantageous embodiment of the device according to the invention, it is also proposed that the locking pin is formed at its end facing the receiving end with a phase and a rounding of its front edge and a hollow end, while in its rear end face a blind hole for fixing the having an end of the spring element preferably designed as a compression coil spring. The other end of the spring element is supported by a counter-holder inserted into the axial bore for the locking pin and formed with a centering tip, which preferably has a Y-shaped profile cross-section and in which the longitudinal grooves formed between its profile limbs simultaneously provide the pressure medium venting of the axial bore are.
The formation of the receiving end of the locking pin with the described defined contour serves to ensure that the entering during the unlocking process from a certain point torque load of the locking pin does not jamming of the same causes or allows a safe and accelerated unlocking of the locking pin. At this, shortly after the beginning of pressurizing the A-pressure chambers of the device and the corresponding associated with this recording of the locking pin point of the locking pin has not yet completely shifted into its unlocked position, in the game by the constantly increasing pressure of the hydraulic pressure means a relative rotation relative to the game inserted between the impeller and the drive wheel of the device and thereby exerts a shear force or torque on the locking pin occurring on the lateral surface of the locking pin contour edge of its recording. Since the receiving end of the locking pin at this point, however, the mentioned phase and the subsequent rounding of the front edge, thus on the one hand jamming of the locking pin is avoided and on the other hand creates an additional roll-induced catapult effect, in which the acting torque is converted into an axial force and used to accelerate the axial movement of the locking pin in its unlocked position.

The hollow design of the receiving side end face of the locking pin, however, has proved to reduce the adhesion forces between the face of this end face and the stop surface in the receptacle of the locking pin to be advantageous and thereby contributes that only the adhesion forces between the resulting annular surface on the end face of the locking pin and the stop surface must be overcome in the recording, to a shortening of the unlocking at.

With regard to the arranged in the rear end face of the locking pin bottom hole in which one end of the spring coil formed as a compression spring element is fixed, alternatively there is also the possibility to completely omit them, if the compression coil spring used not smaller than intended in diameter smaller than the locking pin but approximate has the same diameter or if instead of the compression coil spring, for example, a one-sided the diameter of the locking pin having conical spring is used. It is also possible to support the other end of the spring element instead of the centering of the described counter-holder on a used as a socket or other suitable counter-holder, which has a central and / or more concentric bores for pressure medium venting of the axial bore, or form the axial bore as a stepped bore, in which the resulting shoulder of the bore is used to support the other end of the spring element and the pressure medium venting takes place through the diameter-reduced part of the axial bore. The pressure fluid venting takes place regardless of their execution advantageously always against the existing atmospheric pressure and is executable in the same way both chain-driven and belt-driven devices, the vented pressure medium in a chain drive is discharged directly into the cylinder head and belt drives via an additional flange seal on the camshaft-facing side wall of the device in a tank line in the camshaft.

As a further expedient development of the device according to the invention, it is also proposed with respect to the recording of the locking pin to incorporate this in the camshaft side facing away from the drive wheel and position such that the square-shaped contour is arranged at mounted device below the radial end of one of the boundary walls of the drive wheel and their with a quarter-circle course reaching up to the level of the stop surface of an adjacent boundary wall of the drive wheel worm groove opens from a direction of rotation of the impeller into the contour. The side of the opening worm groove opposite side of the contour of the recording is additionally formed with a hardened inlet radius to facilitate the engagement of the locking pin in the recording, while the corners of the contour are rounded with a diameter of the locking pin adapted radius. The reason of the recording also has two different depth levels, of which the upper level is formed as a stop surface for the receiving side end face of the locking pin. The incorporated into the upper level lower level of the receiving ground, however, has a transition to the inflowing worm groove and is provided for supplying the hydraulic pressure medium to the end face of the locking pin. In this case, the entering worm groove preferably has a square or approximately square cross-section and is incorporated with a smaller depth than the receptacle in the side wall of the drive wheel. However, other suitable cross-sections for the worm groove and / or an equal or uniform depth of the worm groove that merges into the lower plane of the receptacle are also conceivable here.

The as mentioned above in its surface by a defined game larger than the cross-sectional area of the locking pin formed contour of the recording serves, moreover, on the one hand the balance of the radial bearing clearance between the On the radial end faces of the boundary walls of the drive wheel mounted impeller and the drive wheel and on the other hand, the compensation of production-related position tolerances between the locking pin in the wheel hub of the impeller and its inclusion in the side wall of the drive wheel both in the radial and in the circumferential direction of the device. In addition, it allows the enlarged trained recording to adjust during assembly of the device optimal clearance for the locking pin to avoid jamming of the locking pin in the recording. The sealing of the enlarged receptacle and the entering worm groove against internal pressure medium leaks takes place through the side of the wheel hub of the impeller facing away from the camshaft, which rests against the inner surface of the camshaft side wall of the drive wheel when the device is mounted.

The inventively designed device for changing the timing of gas exchange valves of an internal combustion engine, in particular rotary piston adjustment for rotational adjustment of a camshaft relative to a crankshaft thus has over the known from the prior art devices has the advantage that by the displacement of the locking of a wing of the impeller in the hub of the impeller or by the significant shortening of the distance between the longitudinal axis of the lock and the longitudinal center axis of the device on the one hand substantially increases the rigidity of the locked connection between the impeller and the drive wheel and on the other hand significantly reduces the forces acting on the locking pin during engine operation centrifugal forces become. Since the lock is thus no longer located in the area of the pressure chambers of the device and outside of the pressure medium lines to these pressure chambers, both centrifugal force as well as by accumulating dirt particles in the hydraulic pressure fluid related malfunction of the lock are almost impossible. Likewise, it is thereby possible to form the wings of the impeller less massive, for example in plate form and thus to reduce the manufacturing cost of the device and to increase the number of possible work spaces in the device.

In addition, the inventively designed device has the advantage that the uniformly formed on its entire length locking pin is easy and inexpensive to produce and has a low space requirement, so that the manufacturing cost of the device are further reduced and the device even in confined spaces in the engine compartment is universally applicable. The special design of the recording of the locking pin and standing with the recording operatively connected end face of the locking pin are the cause that no more component loads between the impeller and the drive wheel of the device occur during locking and that when unlocking a jamming of the locking pin in the Recording is no longer possible.

In addition, the connection of the recording of the locking pin exclusively with one of the A-pressure chambers of the device has the particular advantage that a targeted locking of the device when stopping the engine is possible. Since when switching off the internal combustion engine and thus in de-energized control valve of the device, the pressure medium pressure applied to the B-pressure chambers of the device, the impeller is usually rotated under volume minimization of the respective A-pressure chambers of the device in the Necessary for the start of the engine base position in which the Locking pin then locks reliably. In compliance with such a logic for the control valve, that is, always switch the pressure medium pressure when the internal combustion engine to the pressure chambers of the device, which still rotate the impeller in the desired base position, the inventively designed device is thus both on intake camshafts with locking in "later "Timing of the gas exchange valves as well as exhaust camshafts and SOHC engines with locking in 'early' timing of the gas exchange valves used.

When using the inventively designed device on exhaust camshafts or on SOHC engines, it still has more than beneficial proven that in the direction of "late", so in the direction of the base position away acting drag torque of the cam to compensate for the adjustment of the device and to support the rotational movement of the impeller in the base position of the internal combustion engine by an additional spring element compensate for that on the drive wheel and the impeller attacks and generates a preload torque between them. In the case of the device designed according to the invention, this can be realized in a particularly advantageous manner by a flat strip coil spring arranged outside the camshaft side wall of the drive wheel whose outer suspension point is formed by an elongated fastening screw for the side walls and whose inner suspension point is connected to the central screw of the device.

Brief description of the drawings

Figur 1

einen Längsschnitt B-B nach Figur 2 durch eine erfindungsgemäß ausgebildete Vorrichtung;

Figur 2

einen Querschnitt A-A nach Figur 1 durch eine erfindungsgemäß ausgebildete Vorrichtung;

Figur 3

eine vergrößerte Ansicht der Einzelheit X gemäß Figur 1 auf den Verriegelungsstift der erfindungsgemäß ausgebildeten Vorrichtung;

Figur 4

eine Draufsicht auf die Innenseite der nockenwellenabgewandten Seitenwand des Antriebsrades der erfindungsgemäß ausgebildeten Vorrichtung;

Figur 5

eine vergrößerte Ansicht der Einzelheit V gemäß Figur 4 auf die Aufnahme des Verriegelungsstiftes der erfindungsgemäß ausgebildeten Vorrichtung;

Figur 6

einen Querschnitt VI-VI nach Figur 5 durch die Aufnahme des Verriegelungsstiftes der erfindungsgemäß ausgerichteten Vorrichtung.

The invention will be explained in more detail with reference to an embodiment and is shown schematically in the accompanying drawings. Showing:

FIG. 1

a longitudinal section BB after FIG. 2 by a device designed according to the invention;

FIG. 2

a cross section AA after FIG. 1 by a device designed according to the invention;

FIG. 3

an enlarged view of the detail X according to FIG. 1 on the locking pin of the device according to the invention;

FIG. 4

a plan view of the inside of the camshaft side facing away from the drive wheel of the inventive device;

FIG. 5

an enlarged view of the detail V according to FIG. 4 to the inclusion of the locking pin of the inventively designed device;

FIG. 6

a cross-section VI-VI after FIG. 5 by receiving the locking pin of the device according to the invention.

Detailed description of the drawings

From the FIGS. 1 and 2 clearly shows a device 1 for changing the timing of gas exchange valves of an internal combustion engine, which is a rotary piston adjusting device for adjusting the rotational angle of a not shown Camshaft with respect to a likewise not shown crankshaft of an internal combustion engine is formed. This device 1 is attached to the drive-side end of a camshaft mounted in the cylinder head of the engine and designed in principle as a hydraulic actuator, which in dependence on various operating parameters of the internal combustion engine by the in FIG. 1 33 is controlled hydraulic valve.

Furthermore, in the FIGS. 1 and 2 to see that the device 1 consists essentially of a standing with the crankshaft of the engine drivingly connected drive wheel 2 and a rotatably connected to the camshaft of the engine impeller 3, wherein the impeller 3 is pivotally mounted in the drive wheel 2 and with this in drive connection stands. The drive wheel 2 in this case has a cavity formed by a hollow cylindrical peripheral wall 4 and two side walls 5, 6, in which five equally circumferentially distributed hydraulic working chambers 9 are formed by five directed to the longitudinal center axis of the device 1 radial boundary walls. The impeller 3 of the device 1 accordingly has on the circumference of its hub 10 five uniformly circumferentially distributed and each radially into a working space 9 of the drive wheel 2 extending wings 11, which divide the working spaces 9 in each case an A-pressure chamber 12 and a B-pressure chamber 13 that cause a pivotal movement or fixation of the impeller 3 with respect to the drive wheel 2 and thus a rotational angle adjustment or hydraulic clamping of the camshaft relative to the crankshaft with selective or simultaneous pressurization with a hydraulic pressure means.

Furthermore, in particular FIG. 1 It can be seen that the device 1 to avoid a resulting from the alternating torques of the camshaft stop clatter of the impeller 3 at start of the internal combustion engine has a separate locking element 14, with the impeller 3 falls below a required for adjustment pressure medium pressure in a preferred base position within its adjustment range with the Drive wheel 2 is mechanically coupled. This locking element 14 is in arranged parallel to the longitudinal center axis of the device 1 bore in the impeller 3 and displaceable by a spring element 15 in a locking position within a receptacle 16 in the side wall 5 of the drive wheel 2. By connecting the receptacle 16 of the locking element 14 with at least one pressure chamber 12 or 13 within the device 1, it is possible to hydraulically move the locking element 14 in pressurizing the pressure chambers 12, 13 again in its unlocked position within the bore in the impeller 3.

In particular the FIGS. 1 to 3 is in this respect still be removed that the locking element 14 is formed according to the invention as uniform over its entire length locking pin, which is arranged in a continuous axial bore 17 in the hub 10 of the impeller 3. In FIG. 2 It can clearly be seen that the longitudinal axis of this axial bore 17 has the smallest possible distance from the longitudinal central axis of the device 1, in order to minimize the centrifugal force influences on the locking element 14 that arise during engine operation. In addition, the locking element 14, as shown FIG. 3 emerges on the receiving side formed with a phase 19 and a rounding 20 of its front edge, which accelerate the axial movement of the locking element 14 in its unlocked position while avoiding it in jamming. Adhesion forces of the locking element 14 in the receptacle 16 are additionally avoided by the hollow formation of the front end 21 of the locking element 14, which is also visible in FIG. 3. On its rear end face 22, however, the locking element 14 has a blind bore 23 in which, as well as from FIG. 3 can be removed, which is fixed one end of the compression spring designed as a spring element 15. The other end of this spring element 15 is supported on an inserted into the axial bore 17 and formed with a centering tip 24 abutment 15, which has a Y-shaped profile cross-section and in which the longitudinal grooves formed between its profile legs 26 at the same time for pressure fluid venting the axial bore 17 are provided.

In the FIG. 4 recognizable receptacle 16 of the locking element 14 further has according to the invention a quadrangular and in its surface by a defined all-sided game greater than the cross-sectional area of the locking member 14 formed contour and is formed with an opening worm groove 18, which only with an unpressurized in locking position A-pressure chamber 12 of the device 1 is connected. This ensures that the receptacle 16 of the locking element 14 is acted upon only upon pressurization of the A-pressure chambers 12 of the device 1 via the worm groove 18 with the pressure of the hydraulic pressure medium and thus the locking member 14 is moved to its unlocked position.

In addition, is off FIG. 4 It can be seen that the receptacle 16 of the locking element 14 is incorporated into the side wall 5 of the drive wheel 2 facing away from the camshaft and is positioned such that its quadrangular contour is arranged below the radial end face 27 of a limiting wall 7 of the drive wheel 2, indicated by dashed lines in the drawing. In this case, the worm groove 18 has a quarter-circle course up to the level of the stop surface 28 of an adjacent boundary wall 8, also shown in phantom, and opens into the contour of the receptacle 16 from a side lying in the direction of rotation of the impeller 3. The side of the worm groove 18 opposite side of the contour of the receptacle 16, however, as the magnifications of FIGS. 5 and 6 show, formed with a hardened inlet radius 29, which facilitates the engagement of the locking element 14 in the receptacle 16. Likewise, in the FIGS. 5 and 6 shown that the unspecified corners of the contour with a diameter of the locking pin 14 corresponding radius are rounded and that the bottom of the receptacle 16 has two different depths levels 30, 31. The upper level 30 is formed as a stop surface of the locking pin 14 in the receptacle 16, while the incorporated into the upper level 30 lower level 31 has a transition 32 to the opening worm groove 18 and is provided for supplying the hydraulic pressure medium to the end 21 of the locking element 14 ,

LIST OF REFERENCE NUMBERS

1

contraption

2

drive wheel

3

impeller

4

peripheral wall

5

Side wall

6

Side wall

7

boundary wall

8th

boundary wall

9

working space

10

wheel hub

11

wing

12

A pressure chamber

13

B-pressure chamber

14

locking element

15

spring element

16

admission

17

axial bore

18

worm groove

19

phase

20

rounding

21

hollow front side

22

back end face

23

blind hole

24

centering

25

backstop

26

longitudinal grooves

27

Radial front end

28

stop surface

29

entry radius

30

upper level

31

lower level

32

crossing

33

hydraulic valve

Claims (4)

1. Device for varying the control times of gas exchange valves of an internal combustion engine, in particular a rotary-piston adjustment device for adjusting the angle of rotation of a camshaft with respect to a crankshaft, having the following features:

   ■ the device (1) is attached to the drive-side end of a camshaft mounted in the cylinder head of the internal combustion engine and is designed in principle as a hydraulic actuator which can be controlled as a function of various operating parameters of the internal combustion engine;

   ■ the device (1) is composed substantially of a drive wheel (2), which is drive-connected to a crankshaft of the internal combustion engine, and a vane wheel (3) which is rotationally fixedly connected to a camshaft of the internal combustion engine;

   ■ the drive wheel (2) has a cavity formed by a hollow cylindrical peripheral wall (4) and two side walls (5, 6), in which cavity at least one hydraulic working chamber (9) is formed by at least two radial boundary walls (7, 8);

   ■ the vane wheel (3) has, on the periphery of its wheel hub (10), at least one vane (11) which extends radially into a working chamber (9) of the drive wheel (2) and which divides said working chamber (9) respectively into an A pressure chamber (12) and a B pressure chamber (13);

   ■ the pressure chambers (12, 13), upon being pressurized selectively or simultaneously with a hydraulic pressure medium, effect a pivoting movement or a fixing of the vane wheel (3) with respect to the drive wheel (2), and therefore of the camshaft with respect to the crankshaft;

   ■ if the pressure of the pressure medium falls below a pressure required for adjustment, the vane wheel (3) can be mechanically coupled, in a preferred base position within its range of adjustment, to the drive wheel (2) by a separate locking element (14);

   ■ the locking element (14) is arranged in a bore, which is parallel to the longitudinal central axis of the device (1), in the vane wheel (3) and can be moved by a spring element (15) into a locked position within a receptacle (16) in one of the side walls (5, 6) of the drive wheel (2);

   ■ the receptacle (16) of the locking element (14) is connected to at least one pressure chamber (12 or 13) within the device (1), such that, upon pressurization of said pressure chamber (12 or 13), the locking element (14) can be moved hydraulically into an unlocked position within the bore in the vane wheel (3);

   ■ with the locking element (14) being designed as a locking pin which is uniformly cylindrical along its entire length, and being arranged in an axial bore (17) in the wheel hub (10) of the vane wheel (3), the longitudinal axis of which axial bore (17) is at the smallest possible distance from the longitudinal central axis of the device (1),

   characterized in that

   ■ the receptacle (16) of the locking element (14) has, in one of the side walls (5, 6) of the drive wheel (2), a tetragonal contour which is designed so as to be larger in terms of area, by a defined play on all sides, than the cross-sectional area of the locking element (14), and said receptacle (16) is formed with an opening-in worm groove (18) for the supply of pressure medium,

   ■ which worm groove (18) is connected exclusively to an A pressure chamber (12), which is unpressurized in the locked position of the vane wheel (3), of the device (1) and via which the receptacle (16) of the locking element (14) can be acted on with the pressure of the hydraulic pressure medium only upon pressurization of the A pressure chambers (12).
2. Device according to the preamble of Claim 1, characterized in that

   ■ the locking element (14) is formed with a chamfer (19) and with a rounding (20) of its end-side edge and also with a hollow end side (21), while said locking element (14) has, in its rear end side (22), a base bore (23) for fixing the one end of the spring element (15) which is preferably designed as a coil pressure spring,

   ■ the other end of which spring element (15) is supported on a counter bracket (25), which is inserted into the axial bore (17) and is formed with a centring tip (24) and has a Y-shaped profile cross section, in which the longitudinal grooves (26) which are formed between the profile limbs of said Y-shaped profile cross section are simultaneously provided for pressure medium ventilation of the axial bore (17).
3. Device according to the preamble of Claim 1, characterized in that

   ■ the receptacle (16) of the locking element (14) is preferably formed into that side wall (5) of the drive wheel (2) which faces away from the camshaft, and said receptacle (16) is preferably positioned such that, when the device (1) is assembled, the tetragonal contour of said receptacle (16) is arranged below the radial end side (27) of one of the boundary walls (7 or 8) of the drive wheel (2),

   ■ with the worm groove (18), which preferably extends with a profile in the shape of a quadrant of a circle up to the level of the stop surface (28) of an adjacent boundary wall (8 or 7) of the drive wheel (2), of said receptacle (16) being arranged so as to open out into the contour of the receptacle (16) from a side situated in the rotational direction of the vane wheel (3).
4. Device according to Claim 3, characterized in that

   ■ that side of the contour of the receptacle (16) which is situated opposite the side with the worm groove (18) is formed with a surface-hardened run-in radius (29), while the corners of the contour are rounded with a radius which is adapted to the locking element (14), and the base of the receptacle (16) has two planes (30, 31) of different depths,

   ■ of which planes (30, 31) the upper plane (30) is designed as a stop surface of the locking element (14) while the lower plane (31), which is formed into the upper plane (30), has a transition (32) to the opening-in worm groove (18) and is provided for conducting the hydraulic pressure medium to the end side (21) of the locking element (14).

Images