DE19850947A1 - Device for controlling opening and closing times of gas exchange valves of internal combustion engine comprises at least one drive device, at least one camshaft with at least one cam for operating at least one valve - Google Patents

Abstract

The opening and closing times of the gas exchange valves of an internal combustion engine are controlled by a device comprising at least one drive, at least one camshaft (28) with at least one cam (50) for the operation of at least one valve and at least one hydraulic adjustment device for the relative rotary angle between the drive device and the camshaft. The adjustment device has at least one movable component with at least one surface activatable with a hydraulic fluid. A hydraulic oil pressure source is provided together with a hydraulic oil outlet. At least one connecting device is incorporated which creates a timewise hydraulic connection of the pressure source with the at least one surface. The use of a forced control device causes the hydraulic activation of the adjustment device to be at least partly influenced dependent upon the absolute rotary angle of the camshaft.

Description

Field of application of the invention

The invention relates to a device for controlling the opening and Closing times of gas exchange valves of an internal combustion engine as well Process for the production of such.

Background of the Invention

Devices for controlling the opening and closing times of gas exchange Valves of an internal combustion engine have been known for some time. On Part of these devices is usually based on the principle that in Torque flow between a belt drive and the camshaft an axial displaceably mounted piston is arranged. This piston is with the Rie mentrieb or the camshaft coupled such that an axial displacement of the piston in a relative rotation angle adjustment of belt drive and Noc  kenwelle is converted, whereby gear pairs are often used, at least one of which has helical teeth. The controlled axial displacement Exercise of the piston is realized by means of a hydraulic arrangement. Here a chamber adjoins one or both end faces of the piston, which is connected to a pressure oil source, so that the respective end faces of the Pistons can be acted upon hydraulically.

Another variant of these devices is based on the principle that in Torque flow between a belt drive and the camshaft a Ra dial piston or vane cell adjuster is arranged. Such, e.g. B. in the Arrangements disclosed in DE 39 37 644 A1 or EP 0 777 037 A1 an impeller provided with radial vanes, which with a camshaft is rotatably coupled. These wings extend in several, in um cells extending in the longitudinal direction of a cellular wheel connected to the drive wheel is rotatably connected and surrounds the impeller radially on the outside. Here the cells from the wings came into a first and a second came more divided. These chambers are via hydraulic oil supply lines each can be loaded with hydraulic oil. With different loads these chambers - as a rule due to the pressure difference - a right sulting force on the wings. The Flü follow this resulting force gel in the circumferential direction, so that depending on the orientation of the resulting Force the angle of rotation of the camshaft in a first or second orientation adjusted with respect to the angle of rotation of the drive wheel.

With such devices, there is a requirement that the adjustment of the camshaft under all operating conditions accuracy and sufficient adjustment speed can. At high oil temperatures or low engine speeds or at Low pressures in the engine oil circuit or in the hydraulic system increase the Ge driving of inaccuracies in the adjustment of the camshaft Phase angle. This is primarily due to dynamic camshaft torques lead back, which in turn are caused in particular by the fact that the cam in the valve opening phase (running cam) additional stroke  has to work against the force of a valve spring while in the Ab running phase (closing the valve) a part of this stored in the spring Energy is given back to him. Since the camshaft is against the Piston or the wing and this or this in turn against the hydraulic oil supports in one of the chambers, this results in pressure fluctuations in the Chambers. These lead to an "early" adjustment (adjustment the camshaft in the direction of its direction of rotation) to a pressure increase in the pressurized chamber during the opening of the cam and to a decrease in pressure in this chamber as the Noc expires kens. The reverse applies for an adjustment in the "late" direction (opposite direction) tion regarding the chamber then pressurized. With an adjustment in In the "early" direction, this leads, for example, to the fact that during emergence of the cam oil due to the pressure increase in the pressure chamber can be pushed and thus the adjustment of the camshaft in the ange aspired direction is counteracted while in the expiry phase as a result of the reduced pressure the adjustment in the desired direction below is supported.

To compensate for these pressure fluctuations, it has therefore been proposed to place a check valve inside the pressure oil supply line. A such arrangement of a check valve causes an increase in Ver positioning accuracy, because the fluid columns protruding into the chambers on this can support. However, such an arrangement does not stop Optimum, so that further improvements are desirable. So be this additional component means both the risk of failure and the costs elevated. Furthermore, the valve means a flow that should not be neglected resistance that leads to pressure losses. In the worst case, the over critical excitation or the excitation in the range of the natural frequency can even to a significant decrease in impermeability towards the pressure source.

Object of the invention

The invention is therefore based on the object, a device and a Process for their preparation - to create, which with improved flow behavior more cost-effectively and with increased operational reliability of your Components allows a safe adjustment of the camshaft rotation angle.

Summary of the invention

The object is achieved by the subject matter of claim 1 solved. Preferred developments of the invention are the subject of the Un claims.

According to the invention, a device for controlling the opening is provided Opening and closing times of gas exchange valves of an internal combustion engine with at least one positive control device through which the hydrauli act on the adjusting device depending on the absolute th rotation angle of the camshaft and / or the cams at least temporarily and / or at least partially limited.

A device according to the invention has at least one drive means, such as a belt or a toothed belt wheel, and at least one camshaft on whose cams are used to actuate valves. The valves prove for example, a spring against the force of the cam ge the valve can be opened during the closing movement of the valves by the in the Spring stored energy is at least supported. Via a hydraulic actuatable and preferably axially displaceably mounted adjustment device, such as a piston device or a piston or a radial piston or Flü gel cell adjuster, the angle of rotation between the drive means and adjust the camshaft. For this purpose, e.g. B. the adjustment device or the Piston coupled to the drive means or the camshaft such that a Axial displacement of the piston in a relative angle adjustment of An propellant and camshaft is converted. For example, in  Torque flow between drive means and adjusting device or piston and between the piston and the camshaft at least one pair of gears arranged, at least one of which has helical teeth.

It is also preferred to use an adjusting device instead of the piston device Provide radial piston or vane adjustment device. These wings According to the invention, the cell adjusting device has a camshaft side Ordered impeller with blades that are essentially radial Extend direction. This impeller is non-rotatably coupled to the camshaft pelt. The blades of the impeller extend into the cells one around the Impeller extending around the cellular wheel. The wings divide the cells each in a first and a second chamber. These chambers stand each with a hydraulic oil supply line in connection. By correspond Filling processes of these chambers can be compared to the impeller adjust the cell wheel relatively in the circumferential direction. So that the angle of rotation between the drive device connected to the cellular wheel and the Camshaft changed.

A hydraulic fluid supply is provided for the adjustment of the adjustment device direction provided, the at least one hydraulic oil pressure source and / or Hydraulic oil discharge device and at least one connection Direction for at least temporarily hydraulic connection of the hydraulic oil Pressure source and / or hydraulic oil discharge device with the at least one Surface of the connecting device. This hydraulic fluid supplier supply device has, for example, hoses, bores or other Lines on.

For example, the positive control device orders at least two defined positions of a movably arranged component each be agreed, defined condition. These are preferred States generated purely mechanically. It preferably assigns at least two different angular positions of the camshaft or the cam each one Switching state of the hydraulic fluid supply device too. For example  point at least during an adjustment movement of the piston "early", i.e. a camshaft in the direction of rotation of the camshaft Angle of rotation adjustment, in the cam positions in which the cam has a Ven actuated the tappet in such a way that the distance between the tappet and the cam shaft axis enlarges a flow connection between a pressure source and a first chamber adjoining a piston is interrupted (first state) while ver at least one of this cam position different cam position is at least partially open. Is accordingly for example with an opposite adjustment the flow connection interrupted when the plunger acts under the action of the Force of the valve spring supported by the cam in the direction of the camshaft emotional. It is therefore preferred that the flow connection is then interrupted is when fluctuations - particularly preferred the desired adjustment movement opposite fluctuations - in force or torque course or load side act on the cam or the camshaft the pressure conditions in the chamber would (would) react. Especially before the flow connection is interrupted when (superimposed) Fluctuations in the camshaft torque curve cause an increase in pressure the chamber (would). It is also preferred that the flow connection at least during the mechanical interaction of cams and valve tappet is interrupted, with the underside going beyond Period for the different valves or cylinders at least partially is different. The states are preferably independent of the Compressibilities of the hydraulic oil and depend essentially only on that Position of the movably arranged component.

A device according to the invention offers various advantages. So enabled allows a defined opening and closing of the pressure supply line any point in time without an additional component, such as a back impact valve, is required or failure at certain pressure fluctuations frequency threatens. Furthermore, the invention also enables adjustment at low pressures - even those that are just about to adjust the Sufficient camshaft. Also an increase in the adjustment speed  Low pressures are made possible according to the invention. Also let through the invention always the pressure oil control times to the respective engine operation just adjust the stand.

The positive control device preferably has a switch device for at least temporarily diverting a fluid flow in the connection direction up. Here, for example, in a first component position, such as one determined cam position, a flow connection between a first Line that leads, for example, to a pressure chamber with a second Lei tion, for example, in a chamber located on the piston or on the wing leads, switched while it is interrupted with a third line, and at a second cam position the second line from the first under the same early connection of first and third line disconnected.

The positive control device particularly preferably has an underside chungseinrichtung on a fluid flow in the presence of a first component position interrupts and enables a second component position. It is particularly preferred that an element of the positive control device from the inlet and / or outlet line arrangement to the piston closing chamber is included.

According to a preferred embodiment of the invention, the increase or decrease Run line at least partially through the camshaft and / or by little least a cam interior and / or at least partially in one in the considerably led by the cam spanned level or is ent speaking line walling or limitation of a cam and / or camshaft surface formed. The line break preferably has chungs or the switch device on a movable area, the Movement or trajectory to the movement of the cams and / or the Camshaft is functionally coupled, for example by a mechanical cal positive coupling (with) is determined. This moving area is be a hydraulic line section is particularly preferred, that is to say a region of one Flow line.  

According to a particularly preferred embodiment of the invention, it opens into this movable hydraulic line section during a first time pe period at least a first line section and during a second time period at least a second line section, these two At least partially overlap periods of time, so that during at least a part-time period of a connection between the first and the second Line section is established during another part-time period or time period is interrupted.

The camshaft is particularly preferably at least partially as a hollow shaft is formed, the hydraulic oil flow at least partially by little at least part of the inside of the shaft is guided and being separated from the world at least one opening inside, for example a (radial) bore, extends outwards through the covering of the camshaft. Preferably this opening forms the aforementioned first or second line section.

According to a preferred embodiment of the invention, it leads to a Connecting line section that curves around the longitudinal axis of the Noc kenwelle winds and an angular range in the circumferential direction of the camshaft covers that is smaller than 360 ° and preferably a groove, one with one of the Chambers related line and one with the pressure source in Ver binding line, at least one of these lines at least be in the respective mouth area relative to the connecting line section is arranged movably. The groove particularly preferably extends in the Au Outer surface of the camshaft or in the inner surface of the Noc core shaft with a substantially cylindrical inner surface and at least temporarily and at least partially compared to the camshaft rotatably arranged adjacent component. One of the lines is for example in the component having the groove, while the other Lei tion extends into the other component.

A preferred embodiment of the invention has at least one slide ger for receiving the camshaft, in which part of the flow chamber  extends channels and / or at least from the positive control device is partially included. For example, this slide bearing extends upwards the above-mentioned groove over at least part of the inner circumference catch.

The sliding bearing is particularly preferably opened on the outside by a cylinder head taken. According to a particularly preferred embodiment according to the invention tion form is this plain bearing or this plain bearing bush compared to Cylinder head and movable with respect to the camshaft, preferably rotating movable, arranged. Fixing elements are preferably additionally provided hen. The movable arrangement enables adjustment of the Groove position, which preferably extends in the plain bearing bush. Such rotatable bearing enables by turning the bearing bush To completely block the pressure oil flow to the camshaft adjuster. This is ins Particularly advantageous in the engine start phase to reduce noise.

According to a preferred embodiment of the invention, those of Override device controlled interruption periods during the pressurization of the first chamber and during the pressurization striking the second chamber and / or depending on the act striking valve each different. The invention particularly preferably comprises device according to the invention an adjusting device for adjusting the positively controlled interruption periods and / or interruption lengths and / or for adjusting the position of the positively controlled interruption lengths to the absolute angle of rotation of the camshaft. Even if the terms Un Breaking periods or interruption lengths simplify syn To be used onym is strictly to be distinguished: So be under an interruption length understood a structurally determined size, such as for example the length of a groove-free section along which a line section is passed by when a connection between a chamber and the Pressurized oil source is only made when the line section on the groove is led along. The actual time is below the interruption period to understand who lapses when the connection is broken, which is  for example as a product of the slot length and the relative speed between the groove and the line section results. The adjustment device is an example as a sleeve, such as a bearing bushing in the circumferential direction and / or is axially displaceable. It is preferably in (individual) positions fixable. With an axial displacement, for example, from a first groove with defined length and position of the groove to the absolute angle of rotation of the Noc on a second groove with a different defined length and / or position of one Groove to the absolute angle of rotation of the camshaft can be switched.

According to a particularly preferred embodiment of the invention a symmetrical adjustment curve of the temporal adjustment angle curve with regard to the adjustment specifications "early" - "late" - "early" or - "late" - "early" - "late" enabled. For example, ver different interruption times or periods are provided. Here or there through, for example, by appropriate design of the oil supply Timing the adjustment towards "early", d. H. towards the opposite the slower adjustment direction acting on the camshaft friction torque accelerates while the adjustment towards "late", d. H. towards the with the faster adjustment direction acting on the camshaft friction torque slows down.

This allows the additional arrangement of a spring without great effort avoided in known arrangements to avoid in particular asymmetries in the course of the adjustment curve caused by the friction torque to be brought. Also springs that are known for reducing noise Arrangements can be used, can be by the inventive front save direction without a device of the invention emits greater noise pollution.

It should be noted that the interaction of the individual invented features according to the invention in any combination is preferred. Ins special are also those disclosed by the independent claims Characteristic combinations with omission of one or more characteristics  preferred in each case. Any combination of the claims is also preferred. For the One skilled in the art can see that the exemplary embodiments shown here the invention also a variety of other modifications and designs are conceivable, which are covered by the invention. The invention is limited especially not only to the embodiments shown here.

Brief description of the drawings

The invention will be explained in the following on the basis of exemplary, non-restrictive Embodiments explained in more detail. Show in the accompanying drawings included:

Figure 1 is occurring on a camshaft friction torque-curve over the crank angle, in a schematic and exemplary form.

Fig. 2 in qualitative form, the effects of fluctuations in the Noc kenwellenmoment on the oil pressure in a chamber;

Fig. 3 shows a first exemplary, partially sectioned embodiment of the inven tion;

Fig. 4 shows a second exemplary embodiment of the invention; and

Fig. 5 qualitatively different generatable with the invention symmetrical Verstellwinkelverläufe 90, 92, 94 compared to a rule asymmetri Verstellwinkelverlauf 98th

Detailed description of the drawings

Fig. 1 shows the friction moment normally occurring on a camshaft profile over the crank angle. This experiences an increase 4 when the cam runs up and a decrease 6 when the cam runs down, with the direction of action of the friction torque being reversed.

FIG. 2 shows in qualitative form the oil pressure curve associated with the phenomenon described with reference to FIG. 1 in the adjusting chamber above the crank angle.

Fig. 3 shows an exemplary embodiment of the invention partially sectioned. The pulley 10 is rotatably coupled to the housing cover 12 and the first inter mediate element 14 . The intermediate element 14 has radially on the inside a toothing 16 which meshes the counter toothing 20 arranged on the axially displaceably gela piston device 18 . The piston device 18 has a second toothing 22 which engages in a second counter toothing 26 arranged on the second intermediate element 24 . At least one gear pair 16 , 20 or 22 , 26 is helically toothed. The second intermediate element 24 is rotationally fixed to the camshaft 28 in connec tion and is clamped against the screw 30 against this. The Kolbeneinrich device 18 separates a first chamber 32 from a second chamber 34 . For the axial adjustment of the piston device 18 , these chambers 32 , 34 can each be filled in a controlled manner with pressure oil via the partially shown lines 36 and 38 .

The exemplary embodiment in the area of the cams 40 , 42 is described in more detail below with reference to FIG. 4. The cam 50, which is connected in a rotationally fixed manner to the camshaft 28, is used to act on a valve with (Tas sen) tappet 52 and valve spring 54 . Camshaft 28 rotates in the direction of arrow 56 during operation. Compared to the camshaft 28 and ge compared to the cylinder head 74 , the bearing bush 58 is movably arranged in the arrow directions of the double arrow 60 , so that the position of the circumferential groove 64 arranged on the cylindrical inner surface 62 to the cam 50 or to the point 66 at which the Cam 50 in the direction of rotation 56 touches the plunger 52 for the first time, can be adjusted. So that the flow connection continuing via the line 68 in the direction of the chamber 32 , not shown, is not interrupted by a rotation of the bearing bush 58 , a second circumferential groove 70 adjoins the outside of the bore 72 which extends outward from the circumferential groove 64 and which is in the cylinder head 74 is arranged. The hydraulic oil discharged via line 68 for piston adjustment is supplied from the pressure source (not shown) via the interior 76 of the camshaft 28 designed as a hollow shaft. If from the interior 76 through the wall 78 of the camshaft 28 outward radial Ölver supply bore 80 passes over the circumferential groove 64 with its outer end portion 82 , a flow connection between the interior 76 and the line 68 is made, which is otherwise interrupted. This connec tion is also independent of the position of the oil supply bore 80 to the circumferential groove 64 interruptible by the bore 72 is rotated with the bearing bush 58 such that the bore 72 with its outer end 84 is no longer in contact with the circumferential groove 70 .

It should be noted that fixing elements, not shown, preferably fix the bearing bush 58 outside the adjustment relative to the cylinder head 74 . It should also be noted that with correspondingly rearranged grooves and channels, the bearing bush 58 can also be fixed to the camshaft 28 , the outer casing of the bearing bush 58 being rotatable relative to the cylinder head 74 .

FIG. 5 shows qualitatively different symmetrical displacement angle curves 90 , 92 , 94 that can be generated with the invention in comparison to an asymmetrical displacement angle curve 98 .

Reference list

4th

rise

6

waste

10th

Pulley

12th

Housing cover

14

first intermediate element

16

Gearing of

14

18th

Piston device

20th

Counter toothing

22

second toothing

24th

second intermediate element

26

second counter toothing

28

camshaft

30th

screw

32

first chamber

34

second chamber

36

Line to

32

38

Line to

34

40

cam

42

cam

50

cam

52

Tappet

54

Valve spring

56

arrow

58

Bearing bush

60

Double arrow

62

Inner surface

64

Circumferential groove

66

Point

68

management

70

second circumferential groove

72

Drilling in

58

74

Cylinder head

76

Interior of

28

78

Covering

78

of

28

80

Oil supply hole in

28

respectively.

78

82

End range of

80

84

End of

72

90

symmetrical Verstellwinkelver course

92

symmetrical Verstellwinkelver course

94

symmetrical Verstellwinkelver course

98

asymmetrical adjustment angle curve

Claims (34)

1. Device for controlling the opening and closing times of gas exchange valves of an internal combustion engine

• 1. at least one drive means;
• 2. at least one camshaft ( 28 ) with at least one cam ( 40 , 42 , 50 ) for actuating at least one valve;
• 3. at least one hydraulically actuated adjusting device for adjusting the relative angle of rotation between the drive means and the camshaft ( 28 ), the adjusting device having at least one movably arranged device with at least one surface which can be acted upon by a hydraulic fluid;
• 4. at least one hydraulic fluid supply device having at least one hydraulic oil pressure source and at least one hydraulic oil discharge device;
• 5. at least one connecting device for at least temporarily hy draulic connection of the hydraulic oil pressure source with the at least one surface; and
• 6. at least one positive control device through which the hydraulic loading of the adjusting device as a function of the absolute angle of rotation of the camshaft ( 28 ) can be at least partially influenced.

2. Apparatus according to claim 1, wherein the positive control device device an interruption device, such as a line interruption Device for at least temporarily interrupting the fluid flow in the connecting device. 3. The apparatus of claim 1, wherein the positive control A switch device for at least occasional diversion of the fluid flow in the connecting device. 4. The device according to claim 1, wherein the adjusting device

• 1. has at least one hydraulically actuated and axially displaceably gela piston device ( 18 ) with at least one active surface for receiving a hydraulic fluid;
• 2. has at least one first torque transmission means for transmitting a torque from the drive means to the piston device ( 18 ); and
• 3. has at least one second torque transmission means for transmitting a torque from the piston device ( 18 ) to the camshaft ( 28 );
• 4. wherein at least one torque transmission means has a device for converting an essentially translatory movement into a movement with at least one rotary component.

5. The device according to claim 1, wherein the adjusting device

• 1. an impeller with substantially radially outwardly extending blades and
• 2. has a cellular wheel with cells arranged essentially in the circumferential direction, wherein
• 3. The wings protrude into the cells such that the cells are each divided into a first and a second at least partially by a wing of the separate chamber;
• 4. the vanes are at least temporarily and at least partially movably arranged with respect to the impeller; and
• 5. the chambers are each connected to an oil supply device.

6. The device according to claim 1, wherein the inlet or outlet line we at least partially through the camshaft ( 28 ) is guided. 7. The device according to claim 1, wherein the inlet or outlet line we is at least partially guided through at least one cam interior. 8. The device according to claim 1, wherein the inlet or outlet line we at least partially in a substantially through the cams ( 40 , 42 , 50 ) spanned plane. 9. The device according to claim 2, wherein the line interruption device has a movable area, the movement of which is functionally coupled to the movement of the cams ( 40 , 42 , 50 ). 10. The device according to claim 3, wherein the switch device has a movable area, the movement of which is functionally coupled to the movement of the cams ( 40 , 42 , 50 ). 11. The apparatus of claim 9, wherein the movable area is a Hy draulikleitungsabschnitt is. 12. The apparatus of claim 11, wherein

• 1. the movable hydraulic line section is connected to at least one first line section during a first time period, the first line section opening into the hydraulic line section;
• 2. the movable hydraulic line section is connected to at least one second line section during a second time period, the second line section opening into the hydraulic line section; and
• 3. These first and second time periods overlap at least during a part-time period.

13. The apparatus of claim 1, wherein the camshaft ( 28 ) is at least partially designed as a hollow shaft, wherein

• 1. at least a portion of the hollow portion ( 76 ) of the hydraulic oil supply device is included; and
• 2. at least one opening extends outwards from this hollow area ( 76 ) through the wall ( 78 ) of the camshaft ( 28 ).

14. The device according to claim 11, which has a connecting line section into which at least temporarily at least one feed line section opens and into which at least temporarily at least one discharge line section opens,

• 1. wherein the supply line section is in flow connection with a pressure source and wherein the discharge line section is in flow connection with a chamber ( 32 , 34 ) comprised by the adjusting device ( 18 ); and
• 2. wherein at least the discharge line section relative to the connec tion line section is movably arranged, so that this movably arranged section is at least temporarily separable from the connec tion line section.

15. The apparatus of claim 14, wherein the connecting line section is a curved around the longitudinal axis of the camshaft ( 28 ) he extending groove ( 64 ) which in the circumferential direction of the camshaft ( 28 ) covers a circumferential area which is less than 360 °. 16. The apparatus of claim 15, wherein the groove ( 64 )

• 1. in the outer surface of the camshaft ( 28 ); or
• 2. in the inner surface ( 62 ) of a camshaft ( 28 ) with a substantially cylindrical inner surface ( 62 ) encasing and with respect to the camshaft ( 28 ) at least temporarily and partially rotatably arranged adjacent component extends.

17. The apparatus of claim 13, wherein the through the wall of the camshaft ( 28 ) extending outwardly opening is a supply line section. 18. The apparatus of claim 1, wherein the camshaft ( 28 ) is mounted in little least a plain bearing bush ( 58 ), which is at least partially encompassed by the Zwangssteue device. 19. The apparatus of claim 14, wherein the discharge line section in the plain bearing bush ( 58 ) of the camshaft ( 28 ) is at least partially inte grated. 20. The apparatus of claim 14, wherein the Verbindungsleitungsab section in the plain bearing bush ( 58 ) of the camshaft ( 28 ) is at least partially integrated. 21. The apparatus of claim 19, wherein the plain bearing bush ( 58 ) from a bushing device, such as a cylinder head ( 74 ), is taken up. 22. The apparatus of claim 20, wherein the plain bearing bushing ( 58 ) is arranged to be movable relative to the bushing receiving device and with respect to the cam shaft ( 28 ). 23. The device according to claim 1, wherein the positive control means the connection between the pressure oil source and a first chamber ( 32 ) of the adjusting device for adjusting the angle of rotation of the camshaft ( 28 ) in the direction of the direction of rotation of the camshaft ( 28 ) with pressure oil can be acted upon, at least temporarily interrupted when a deceleration torque superimposed on a constant torque is exerted on the camshaft ( 28 ) on the load side. 24. The apparatus of claim 1, wherein the direction of the force control device, the connection between the pressure oil source and a second chamber ( 34 ) of the adjusting device, which is opposed to the direction of rotation of the camshaft ( 28 ) in the direction of rotation of the camshaft ( 28 ) Direction (opposite direction) can be pressurized with oil, is at least temporarily interrupted when an acceleration torque superimposed on a constant torque is exerted on the camshaft ( 28 ) on the load side. 25. The apparatus of claim 23, wherein the cam ( 40 , 42 , 50 ) passes through a run-up phase when the valve is actuated, while the cam ( 40 , 42 , 50 ) pushes a valve tappet ( 52 ) substantially away from the camshaft ( 28 ), and passes through an operational phase during which the valve tappet ( 52 ) approaches the camshaft ( 28 ) again, and the connection between the pressure oil source and the first chamber ( 32 ) is interrupted by the positive control device when the cam ( 40 , 42 , 50 ) is essentially in the run-up phase. 26. The apparatus of claim 23, wherein the cam ( 40 , 42 , 50 ) undergoes an overrun phase when the valve is actuated, while the cam ( 40 , 42 , 50 ) pushes a valve lifter 52 substantially away from the camshaft ( 28 ), and one Runs through the phase, during which the valve tappet 52 approaches the camshaft ( 28 ) again, and the connection between the pressure oil source and the second chamber ( 34 ) is interrupted by the positive control device when the cam ( 40 , 42 , 50 ) in is essentially in the process phase. 27. The apparatus of claim 1, wherein the positive control means, the connection between the pressure oil source and the first chamber ( 32 ) during the run-up phase and during the run-down phase of the cam ( 40 , 42 , 50 ) is substantially interrupted. 28. The apparatus of claim 1, wherein from the positive control device, the connection between the pressure oil source and the second chamber ( 34 ) is substantially interrupted during the run-up phase and during the run-down phase of the cam ( 40 , 42 , 50 ). 29. The apparatus of claim 2, wherein the periods of interruption during the pressurization of the first chamber ( 32 ) and during the pressurization of the second chamber ( 34 ) are different. 30. The device according to claim 2, which an adjusting device for adjusting tion of the positively controlled interruption periods. 31. The device according to claim 2, which an adjusting device for adjusting has the interruption lengths. 32. Apparatus according to claim 2, which has an adjusting device for adjusting the position of the positively controlled interruption lengths to a fi x reference point such as the absolute angle of rotation of the camshaft ( 28 ). 33. The apparatus of claim 1, wherein the positive control device tion per cylinder of the engine, the timing of which differs from all timing  distinguishes ten of the other cylinders, a corresponding characteristic having. 34. The apparatus of claim 1, which has a positive control device from which a symmetrical adjustment curve can be generated, the adjustment curve being the time profile of the adjustment angle of the camshaft ( 28 ) during the adjustment

• 1. from the direction "late" in the direction of "early" and after the elapse after a certain period of time subsequent readjustment in the direction of "late" or
• 2. from the "early" direction to the "late" direction and the subsequent readjustment after the elapse of a certain period of time in the "early" direction

is.