EP2504534B1 - Valve phasing device for internal combustion engine - Google Patents

Description

Field of the invention

The invention relates to a device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine with a hydraulic phase adjusting device, wherein the phase adjusting device can be brought into driving connection with a crankshaft and a camshaft and at least one Frühverstellkammer and at least one Spätverstellkammer which supplied via pressure medium lines pressure medium or from this can be dissipated, with a phasing of the camshaft relative to the crankshaft can be adjusted by pressure medium supply to the adjustment.

Background of the invention

In modern internal combustion engines devices for variable adjustment of the timing of gas exchange valves are used to make the phase position of a camshaft relative to a crankshaft in a defined angular range, between a maximum early and a maximum late position variable. For this purpose, a hydraulic phase adjusting device of the device is integrated into a drive train, via which torque is transmitted from the crankshaft to the camshaft. This drive train can be realized for example as a belt, chain or gear drive. Essential characteristics of such devices are the Phasenverstellgeschwindigkeit and the need for pressure medium. In order to be able to optimally adapt the phase position to the different driving situations, high phase adjustment speeds are desirable. Furthermore, in the context of consumption reduction measures demanded an ever lower pressure medium requirement in order to design the pressure medium pump of the internal combustion engine smaller or to be able to reduce the flow rate when using regulated pressure medium pumps.

Such a device is for example from the EP 0 806 550 A1 known. The device comprises a vane-type phase-adjusting device with a drive element, which is in drive connection with the crankshaft, and an output element, which is non-rotatably connected to the camshaft. Within the phase adjusting device a plurality of pressure chambers are formed, wherein each of the pressure chambers is divided by means of a wing into two counteracting pressure chambers. By supplying pressure medium to or pressure medium discharge from the pressure chambers, the wings are displaced within the pressure chambers, whereby a change in the phase position between the output element and the drive element takes place. In this case, the pressure medium required for the phase adjustment is provided by a pressure medium pump of the internal combustion engine and directed by means of a control valve selectively to the early or late adjustment. The pressure medium flowing out of the phase adjusting device is directed into a pressure medium reservoir, the oil sump of the internal combustion engine. The phase adjustment thus takes place by means of the system pressure provided by the pressure medium pump of the internal combustion engine.

Another device is for example from the US 5,107,804 A known. In this embodiment, the phase adjusting device is also formed in Flügelzellenbauart and several early or late adjustment provided. Unlike the EP 0 806 550 A1 the phase adjustment is not done by pressurizing the pressure chambers by a pressure medium pump, but it is exploited alternating torques acting on the camshaft. The alternating moments are caused by the rolling of the cams on each biased with a valve spring gas exchange valves. The rotational movement of the camshaft during the opening of the gas exchange valves is braked and during closing accelerated. These alternating moments are transmitted to the phase adjusting device, so that the wings are periodically applied in the direction of the late and early attack with a force. As a result, pressure peaks are generated alternately in the advance chambers and the retard chambers. If the phase position is to be kept constant, then a flow of pressure medium from the pressure chambers is prevented. In the case of a phase adjustment in the direction of earlier control times, a drainage of pressure medium from the advance chambers is prevented, even at the times in which pressure peaks are generated in the advance chambers. Increases due to the alternating moments of the pressure in the retardation, so this pressure is used to direct pressure medium from the retardation under the pressure of the generated pressure peak in the advance chambers. Analog succeeds a phase adjustment in the direction of later timing. In addition, the pressure chambers are connected to a pressure medium pump, but only to compensate for leaks from the phase adjusting device. The phase adjustment is thus carried out by diverting pressure medium from the pressure chambers to be emptied into the pressure chambers to be filled under the pressure of the generated pressure peak.

Another device is from the US 2009/0133652 A1 known. In this embodiment, a phase adjustment takes place at low alternating torques, analogous to the device of the EP 0 806 550 A1 , By pressurizing the Frühverstellkammern or Spätverstellkammern by a pressure medium pump, at the same pressure medium discharge from the other pressure chambers to the oil sump of the internal combustion engine. At high alternating torques, analogous to the device from the US 5,107,804 A , These used to direct the pressure medium under high pressure from the Frühverstellkammern (Spätverstellkammern) in the Spätverstellkammern (Frühverstellkammern). In this case, the pressure medium ejected from the pressure chambers is returned to a control valve which controls the pressure medium supply to or the pressure medium discharge from the pressure chambers. This pressure medium passes via check valves within the control valve to the inlet connection, which is connected to the pressure medium pump, wherein a part of the pressure medium is ejected into the pressure medium reservoir of the internal combustion engine.

The EP 2 075 421 A1 discloses a valve for a phaser. The valve comprises a valve piston which is rotatably arranged in a valve housing. Inlets and outlets for pressure oil, are arranged so that by adjusting the valve piston pressure oil can be passed to the adjustment chambers and a locking mechanism. In this case, the locking mechanism can be activated not only in an end position of the camshaft adjuster, ie in a stop in the late or early position, but also in an intermediate position. As a result, a Mittenlagenverriegelung is possible, which may be useful depending on the engine application.

The DE 198 50 947 shows a device for controlling the timing of an internal combustion engine with at least one drive means, at least one camshaft with cam, at least one hydraulically actuated adjusting device for adjusting the relative angle of rotation between the drive means and the camshaft, at least one hydraulic fluid supply means for acting on the adjusting device and at least one Forced control device, by which the hydraulic actuation of the adjusting device in response to the absolute angle of rotation of the camshaft and / or the cam at least temporarily and / or at least partially influenced. In this case, a flow connection to the adjustment chambers is interrupted in a targeted manner when pressure fluctuations caused by torques occur which would react back on the adjustment chambers from the camshaft in the event of cams running up or down.

The US 6,186,104 B1 discloses a vane-type valve timing control apparatus for an internal combustion engine in which a pressure distribution device is interposed between the pressure cells and the control valve driving the same, thereby suppressing disturbing camshaft torques. For this purpose, for example, in a late-adjustment, the oil supply to the pressure cells is interrupted when an early torque occurs. Vice versa at an early adjustment, the supply of oil to the pressure cells is interrupted when a late torque occurs. Comparable with the DE 198 50 947 Thus, a return oscillation of the adjusting device is prevented due to the adjustment against set camshaft moments.

The WO 2008/067935 A2 discloses an adjusting device for phase adjustment of a camshaft relative to a crankshaft of an internal combustion engine having a hydraulic system for supplying the adjusting device, with an adjusting means with working chambers, which are acted upon by a control valve having a control device and connected to each other flow. The control device comprises a coaxial with the axis of rotation of the camshaft adjuster arranged control valve and a Vorschaltventil, which switching between a passive mode in which the adjusting device is adjusted by the alternating moments of the driven camshaft, and an active mode of the camshaft adjuster, wherein the adjusting device by the oil pressure the hydraulic fluid source is hydraulically actively adjusted.

Object of the invention

The invention has for its object to provide a device for variable adjustment of the timing of gas exchange valves of an internal combustion engine with a high Phasenverstellgeschwindigkeit.

Solution of the task

The object is achieved by specifying a camshaft adjuster for a camshaft, are actuated by the cylinder valves of an internal combustion engine, with the camshaft at auflaufenden cam late torques in the direction of later Zylinderventilöffnungszeiten and expiring cam opposite early torques in the direction of early Zylinderventilöffnungszeiten on the Back camshaft adjuster, with a pressure chamber and an adjusting means arranged in the pressure chamber,
wherein the adjusting means divides the pressure chamber into a first sub-chamber and a second sub-chamber,
wherein the first and the second sub-chamber pressure medium can be supplied or discharged from the first sub-chamber and the second sub-chamber pressure medium,
so that the adjusting means is movable by a pressure difference between the first sub-chamber and the second sub-chamber, resulting in a rotation of the camshaft,
wherein, at a higher pressure in the first sub-chamber, a rotation of the camshaft toward early cylinder valve opening times and at a higher pressure in the second sub-chamber results in a rotation of the camshaft toward late cylinder valve opening times
and wherein the supply and removal of pressure medium is controllable by a control device,
wherein by means of the control device optionally a torque mode or a pump mode is adjustable,
wherein in the moment mode predominantly camshaft torques are used to build up pressure in the first sub-chamber or in the second sub-chamber, while in the pump mode, the pressure build-up in the first sub-chamber or in the second sub-chamber predominantly takes place by means of a pressure medium pump available pressure medium.

In the prior art, two strategies for a hydraulic camshaft adjustment have so far been pursued: on the one hand, provision of pressure medium via a pressure medium pump, usually an oil pump of an engine oil lubrication circuit or an exploitation of camshaft torques to generate the necessary adjustment pressure. The first strategy is also referred to as "Oil Pressure Actuated" (OPA) and the second as "Cam Torque Actuated" (CTA). The invention is based on the finding that respective advantages of the OPA and CTA methods can be combined with one another in a favorable manner depending on an operating state of the internal combustion engine. In operating conditions in which a high pump pressure of the pressure medium pump is available Conveniently, the pump mode, ie an OPA method is selected, while at low pump pressures but high camshaft moments, the torque mode, ie the CTA method is used. In this case, of course, an adjustment in the CTA method in addition to the utilization of the camshaft moments are quite supported by the pressure medium pump and vice versa.

The invention is not limited to a particular type of camshaft adjuster, so it can be e.g. a vane positioner are used, in which a plurality of pairs of sub-chambers are formed, wherein the adjusting means is a wing separating the sub-chambers, which is e.g. is integrally formed from a rotor or inserted into this.

According to the invention, the control device comprises a control valve and a rotary shaft arranged on the camshaft, wherein pressure medium via the control valve and the rotary transformer through first openings in the camshaft to the first sub-chamber and second openings in the camshaft to the second sub-chamber can be conducted or discharged, wherein an opening cover in Rotary transformer is arranged so that depending on the rotation angle of the camshaft, the first openings and second openings are enabled or blocked.

In this embodiment, therefore, the supply and discharge of pressure medium to and from the sub-chambers is accomplished by means of a control valve, a downstream rotary transformer and openings or oil passages in the camshaft. The supply and removal of pressure medium is dependent on a rotation angle of the camshaft. This in turn corresponds to the camshaft moments, so that an inflow and outflow of pressure fluid can be synchronized with the respective camshaft torques depending on the desired adjustment direction. Depending on the occurrence of the camshaft moments and the desired setting direction, the opening cover in the rotary transformer releases the first or second openings corresponding respectively to the partial chamber to be actuated. The first and second openings need not be in an integrally formed with the rest of the camshaft area lie, the camshaft is in this sense also an attached component, adapter or the like to be expected, which rotates with the camshaft. The opening cover may be an inside of a cylinder comprising the camshaft, wherein the recesses are formed for example by grooves. Preferably, in each case a groove corresponding to the first and second openings are provided and a further groove for the inlet of pressure medium. The grooves then extend in the circumferential direction along a pitch circle, preferably approximately along a quarter circle in a four-cylinder engine.

Preferably, the opening cover is formed by the inside of a bearing shell, in which the camshaft is mounted, wherein the opening cover is interrupted by recesses so that in the region of the recesses, the first openings and second openings are released, while they are blocked in the region of the opening cover ,

More preferably, the first openings and the second openings are each equally spaced circumferentially at an angular distance and with respect to the opening cover arranged in phase so that a relative rotation of the valve piston relative to the valve housing by the angular distance leads to a geometrically identical arrangement.

Preferably, the pump mode or the torque mode is adjustable by an axial displacement of a valve piston arranged in a valve housing of the control valve. More preferably, the valve housing has a pump opening, through which the supply of pressure medium to either the first sub-chamber or the second sub-chamber is adjustable, so that either the first sub-chamber or the second sub-chamber is under pressure, wherein the flow of pressure medium from the first sub-chamber or the second sub-chamber is adjustable via partial chamber openings in the valve housing.

It is therefore pursued the concept of effecting an adjustment by controlling the flow of pressure medium. Pressure medium is the sub-chambers on the Pump opening supplied in the valve housing, wherein depending on the position of the first openings or the second openings, the pump opening corresponds to the first sub-chamber or second sub-chamber. By releasing the sub-chamber, which is reduced in the desired adjustment, a flow of pressure medium from this sub-chamber is made possible, so that pushed out by the pressure in the other sub-chamber, the pressure medium and the adjustment is effected.

Preferably, five switch positions are adjustable for the relative axial position of the valve piston, wherein
in a first position the pump mode is set for an adjustment of the camshaft after late cylinder valve opening times,
in the second, axially following switching position, the torque mode is set for an adjustment of the camshaft after late cylinder valve opening times,
in the third, axially following switching position a camshaft adjustment is locked,
is set in the fourth, axially following switching position of the torque mode for an adjustment of the camshaft after early cylinder valve opening times and
in the fifth, axially following switching position the pump mode is adjusted for an adjustment of the camshaft after early cylinder valve opening times.

By means of these five switching positions, therefore, sufficient adjustment possibilities are usually already achieved, adapted to a respective engine operating state. For example: While at sufficient pressure of the pressure medium pump, a retardation of the camshaft in shift position one and an advance in shift position five takes place, at low pressure on utilization of the camshaft torques a late adjustment in shift position two and an advance in shift position four. The middle position, switch position three, can be used to block the adjustment.

Preferably, a locking mechanism is provided by which the camshaft adjuster is mechanically locked in a locking position against an adjustment, wherein the locking mechanism is hydraulically unlocked by the pressure means and wherein an inlet of pressure medium to the locking mechanism is switched so that only in an axial switching position of the valve piston, which corresponds to an adjustment after early cylinder valve opening times, the locking device unlocks.

A locking of a camshaft adjuster is required in particular when the engine is switched off, so that no rattling of the freely movable adjusting elements occurs during a restart when there is still no sufficient oil pressure in the adjuster. When switching off the engine is thus generally carried out an adjustment to late and a locking by means of a locking pin. In a conventional embodiment of the locking pin corresponds to one of the sub-chambers, so that after a sufficient pressure build-up after an engine start pressure medium from the sub-chambers of the hydraulically unlockable locking pin pushed back against a spring and the adjuster is unlocked. In the above-described concept it is now provided that a separate inlet of pressure medium to the locking device is switched so that during a state of an adjustment corresponds to late, no pressure fluid passes through the control valve to the locking pin. This ensures that after an engine start the locking mechanism is not already unlocked by a pressure pulse, for example by air, which is inserted by the penetrating pressure medium. Since the basic position is set to late, the adjuster must be unlocked only when the rotational position of the camshaft is to be changed, ie in an adjustment to early. For this purpose, the valve piston is moved axially from the basic position. The fact that the inlet preferably corresponds with locking openings in the camshaft, which are arranged in the axial direction at the same height as the second openings but circumferentially spaced from the second openings, can now be achieved that the inlet only in a switching position to the early released and thus pressure medium reaches the locking pin. Further preferably, two locking openings are arranged in the circumferential direction between each two second openings.

Brief description of the drawings

Figur 1

nur sehr schematisch ein Verbrennungsmotor,

Figur 2

eine schematische Darstellung eines Steuerventils,

Figur 3

ein Ventilkolben und ein Ventilgehäuse,

Figur 4

eine Darstellung der Nockenwellenmomente in Abhängigkeit vom Drehwinkel der Nockenwelle,

Fig. 5-14

eine schematische Darstellung der verschiedenen Schaltstellungen bei OPA Verfahren

Figur 15

eine Darstellung der Änderung der Durchflussmengen an verschiedenen Steuerkanten in Abhängigkeit von der Schaltstellung beim OPA Verfahren,

Figur 16

eine Darstellung der Öffnung der Steuerkanten in Abhängigkeit von der Schaltstellung beim OPA Verfahren,

Fig. 17-20

eine schematische Darstellung der verschiedenen Schaltstellungen bei CTA Verfahren.

Figur 21

eine Darstellung der Änderung der Durchflussmengen an verschiedenen Steuerkanten in Abhängigkeit von der Schaltstellung beim CTA Verfahren,

Figur 22

eine Darstellung der Öffnung der Steuerkanten in Abhängigkeit von der Schaltstellung beim CTA Verfahren

Figur 23

eine erste Variante Steuereinrichtung mit Drehübertrager, Steuerventil und Nockenwelle

Figur 24-28

eine schematische Darstellung der Steuerung von Druckmittel in Abhängigkeit vom Nockenwellenmoment mittels Drehübertrager, Nockenwelle und Steuerventil bei der ersten Variante

Figur 29-29c

eine zweite Variante Steuereinrichtung mit Drehübertrager, Steuerventil und Nockenwelle mit einem Verriegelungsmechanismus

Figur 30-35

eine schematische Darstellung der Steuerung von Druckmittel in Abhängigkeit vom Nockenwellenmoment mittels Drehübertrager, Nockenwelle und Steuerventil bei der zweiten Variante

Figur 36

Ein schematischer hydraulischer Schaltplan für die fünf Schaltstellungen

Further features of the invention will become apparent from the following description and from the drawings in which embodiments of the invention are shown in simplified form. Show it:

FIG. 1

only very schematically an internal combustion engine,

FIG. 2

a schematic representation of a control valve,

FIG. 3

a valve piston and a valve housing,

FIG. 4

a representation of the camshaft torques as a function of the angle of rotation of the camshaft,

Fig. 5-14

a schematic representation of the various switching positions in OPA method

FIG. 15

a representation of the change in the flow rates at different control edges as a function of the switching position in the OPA method,

FIG. 16

a representation of the opening of the control edges as a function of the switching position in the OPA method,

Fig. 17-20

a schematic representation of the various switching positions in CTA method.

FIG. 21

a representation of the change in the flow rates at different control edges as a function of the switching position in the CTA method,

FIG. 22

a representation of the opening of the control edges as a function of the switching position in the CTA method

FIG. 23

a first variant control device with rotary transformer, control valve and camshaft

Figure 24-28

a schematic representation of the control of pressure medium as a function of the camshaft torque by means of rotary transformer, camshaft and control valve in the first variant

Figure 29-29c

a second variant control device with rotary transformer, control valve and camshaft with a locking mechanism

Figure 30-35

a schematic representation of the control of pressure medium as a function of the camshaft torque by means of rotary transformer, camshaft and control valve in the second variant

FIG. 36

A schematic hydraulic circuit diagram for the five switching positions

Detailed description of the drawings

In FIG. 1 an internal combustion engine 1 is sketched, wherein a seated on a crankshaft 2 piston 3 is indicated in a cylinder 4. The crankshaft 2 is in the illustrated embodiment via a respective traction drive 5 with an intake camshaft 6 and exhaust camshaft 7 in combination, with a first and a second camshaft adjuster 11 for variable adjustment of the timing of gas exchange valves 9,10 an internal combustion engine 1 for a relative rotation between the crankshaft 2 and the camshafts 6, 7 can provide. Cams 8 of the camshafts 6, 7 actuate one or more inlet gas exchange valves 9 or one or more exhaust gas exchange valves 10. The inlet gas exchange valves 9 and the exhaust gas exchange valves 10 are referred to below as cylinder valves 12. It can also be provided to equip only one of the camshafts 6, 7 with a device 11, or to provide only one camshaft 6, 7, which is provided with a camshaft adjuster 11. Inlet camshaft 6 and exhaust camshaft 7 are summarized below under the term camshaft 35.

In FIG. 2 a control device 20 is shown in a schematic representation. The control device 20 comprises a valve housing 29 and a valve piston 27 arranged therein. In the example shown, the control valve 20 is arranged with one end in a camshaft 35. There, a return spring 31 acts on the valve piston 27. The return spring 31 is mounted on a thrust bearing 33, designed as a rolling bearing. The valve piston 27 is connected on its end facing away from the camshaft 35 with a magnetic piston 23 which is axially movable by an electromagnet 21. An anti-rotation device 25 connects the magnetic piston 23 with the valve piston 27 so that it can not rotate. Of course, it is also conceivable that an axial movement takes place through the valve housing 29 and a rotational movement through the valve piston 27 with a correspondingly changed environmental configuration.

FIG. 3 shows the valve piston 27 and the valve housing 29 in a perspective view. The valve housing 29 has distributed around its circumference first openings 41. Axially offset to the first openings 41 approximately in the middle of the valve housing 29 are distributed around the circumference third openings 45 are arranged. Again axially displaced then follow second openings 43, which are arranged in the circumferential direction at the same position as the first openings 41. In the hollow valve housing 29, the valve piston 27 is inserted in a rotationally appropriate manner. The valve piston 27 has on its surface 53 an opening cover 51 which is formed by a radially elevated part of the surface 53. The opening cover has at an axial end of the valve piston 27th a first sub-cover 51A and at the opposite end a second sub-cover 51 B on. Both partial covers 51A, 51B are crown-shaped, ie they form a ring around the surface 53 with a respective outer edge BT, AT. The outer edge BT of the first partial cover 51A simultaneously forms the one axial end of the valve piston 27, while the outer edge AT of the second partial cover 51 B simultaneously forms the other axial end of the valve piston 27. The respective axially directed to the center of the surface 53 inner edge PB, PA of the partial covers 51A, 51 B is jagged rectangular. In each case, a crown 52 of a partial cover 51A, 51B in the circumferential direction is oriented so that it lies between two crown prongs 52 of the other partial cover 51 B, 51 A, but with an axial distance between the inner edges PB, PA is.

The valve piston 27 is now rotationally arranged in the valve housing 29, so that the opening cover 51 for each correct phase position, the first openings 41 and second openings 43 releases or blocks. For a pressure medium supply to sub-chambers of a pressure chamber and thus the adjustment of the phase angle of the camshaft is controlled. This will be explained later in detail.

FIG. 4 shows the course of the camshaft moments using the example of a four-cylinder engine, plotted in the y-direction against the rotational position of the camshaft, plotted in the x direction. A following from the friction of the camshaft, at the same speed constant torque is not considered here. Camshaft torques greater than zero correspond to a moment in the direction of an early adjustment, ie in a direction in which an earlier opening of the cylinder valves 12 occurs. Camshaft moments smaller than zero correspond to a moment in the direction of a late adjustment, ie in a direction in which there is a later opening of the cylinder valves 12. It can be seen that the camshaft torques have an approximately sinusoidal course depending on the rotational position of the camshaft. At fixed angular positions, premature torques occur alternately with late torques. This is now utilized specifically in the adjustment of the camshaft.

In FIG. 5 schematically a switching position for adjusting the camshaft is plotted so that the opening cover 51 of the valve piston 27 is shown unwound in a plane. Thus, a rectangular profile with the inner edge PB and a straight outer edge BT results for the first partial covering 51A. Opposite, the second partial cover 51 B is then shown with the inner edge PA and the outer edge AT. At the outer edge AT of the valve piston 27 is connected to the return spring 31, which presses the valve piston 27 against a magnet 21, not shown here.

Also shown schematically are the first openings 41 and the second openings 43, as they are arranged according to the axial position and rotational position of the valve housing 29 relative to the valve piston 27 to the opening cover 51. The first openings 41 correspond to a second sub-chamber B and the second openings 43 correspond to a first sub-chamber A. The sub-chambers A, B are separated by a wing 67 forming an adjusting means 67, which subdivides a pressure chamber 69 into the sub-chambers A, B. The wing 67 is connected to a rotor 65 of a camshaft adjuster 11. The pressure chamber 69 is formed in a stator 63 of the camshaft adjuster 11. A first oil channel 71 leads to the first sub-chamber A, a second oil channel 73 leads to the second sub-chamber B. Shown here is only a section of the camshaft adjuster 11. The camshaft adjuster 11 is designed as Flügelzellenversteller and has a plurality of pressure chambers, sub-chambers, wings and supply channels, the not shown here for the sake of clarity.

An adjustment of the camshaft takes place according to the example of FIG. 5 in the direction of later opening times of the cylinder valves 12 instead: pressurized oil is the second sub-chamber B supplied and discharged from the first sub-chamber A. In the switching position shown here, the first part of the cover 51A, the first openings 41 on the inner edge PB largely free, so that pressurized oil from a pump P via the third openings 45 in the valve housing 29 for second sub-chamber B passes. At the same time, the second openings 43 B are slightly opened by the outer edge AT of the second partial cover 51 B, so that oil from the first sub-chamber A can be discharged into a tank T. The resulting pressure difference between the sub-chambers A, B leads to a force on the wing 67 and thus on the rotor 65 in a rotational direction to the left. The rotor 65 is connected to the camshaft 35. Thus, there is a rotation of the camshaft 35 in the direction of "late".

By the wide release of the first openings 41 a strong Entdrosselung is achieved, whereby the risk of air suction is greatly reduced. With the lower release of the second openings 43 to the tank, a flow control is set.

FIG. 5 to the right of the schematic representation of the valve piston 27 and the first and second openings 41, 43 of the valve housing to the FIG. 4 known profile of the camshaft torques as a function of the rotational angle of the camshaft 35. The valve housing 29 and thus the first and second openings 41, 43 now rotate defined relative to this camshaft profile, as shown by the comparison. Thus, the first and second openings are in FIG. 5 just in sync with a late-cam torque. As a result, the second openings 43 receive a pressure peak in the direction of retardation, as a result of which the oil in the first sub-chamber A can be rapidly ejected. In addition, the oil pressure of the pump P acts on the wide open, as strongly dethrottled first openings 41 in the second sub-chamber B. As a result, there is a very fast adjustment of the camshaft 35. In a similar manner, a rapid adjustment is effected in the direction early.

FIG. 6 shows one of FIG. 5 corresponding image, but now the first and second openings 41, 43 are rotated relative to the opening cover 51. In time, this corresponds to the occurrence of an early camshaft torque. The first openings 41 are only slightly released by the first part cover 51A, while the second openings 43 are released to the pressure supply from the pump P are wide open. The pump P acts on both partial chambers A, B. In sub-chamber B, it now acts against an early torque, which essentially leads to a compensation and no adjustment takes place. The sub-chamber A is flowed through by pressure medium and emptied into the tank T.

The Figures 5 and 6 show a switching position for an adjustment to "late", in which an adjustment to the "Oil Pressure Actuated" - principle, short OPA, is realized and in a direction of adjustment late. This switching position, which thus predominantly utilizes the adjusting force of the pump and where camshaft moments are only supportive, is realized by the illustrated axial position of the valve piston 27. The axial switching position is adjusted by means of the magnet 21. In the example shown, this is the basic position, without energizing the electromagnet 21. As explained, different rotational positions of the valve piston 27 relative to the valve housing 29 are realized in the axial shift position and, in addition, the corresponding camshaft torques are utilized. The FIGS. 7 and 8th show the corresponding representation for an adjustment to "early". Here, the effects for the subchambers A, B are reversed, but otherwise the explanations to the Figures 5 and 6 analogous.

FIG. 9 shows a middle position in which the occurrence of a late-torque, the second openings 43 are completely locked. This blocks an adjustment. Accordingly, in FIG. 10 shown a complete blocking of the first openings 41 upon the occurrence of an early torque. The Figures 9 and 10 thus give an axial switching position of the valve piston 27 again, in which prevents an adjustment of the camshaft 35, so this is to be kept at a given relative angular position to the crankshaft.

In the FIGS. 5 to 10 Switch positions are described in which a high pressure of the pump P is available, that is usually an operating state of the internal combustion engine at high speeds. But should the available pressure of the pump P not be high, especially clearly lower than the pressure exerted by camshaft torques, an adjusted OPA method can be set by selecting further shift positions. This is based on the Figures 11-14 described.

FIG. 11 equals to FIG. 5 , So it should be adjusted in the direction of "late". Here is the late-torque benefit of the adjustment. In FIG. 12 , when an early torque occurs, it becomes clear that due to the now opposite FIG. 6 changed axial position of the valve piston 27 there is a complete coverage of the first openings 41. So while in FIG. 6 was still a high pump pressure to compensate for the early torque at slightly opened first openings 41 was available, at low pump pressure, the early torque is hidden by a complete blocking of the first openings 41. The Figures 13 and 14 again show the corresponding representation in an adjustment to "early".

• Schaltstellung I: Hoher Pumpendruck, Verstellung nach spät, Fig. 5, 6
• Schaltstellung II: Niedriger Pumpendruck, Verstellung nach spät, Fig 11, 12
• Schaltstellung III: Gesperrte Verstellung Fig. 9, 10
• Schaltstellung IV: Niedriger Pumpendruck, Verstellung nach früh, Fig 13, 14
• Schaltstellung V: Hoher Pumpendruck, Verstellung nach früh, Fig 7, 8

The switching positions shown so far can thus be summarized as follows: There are two OPA adjustment provided, one at low and one at high pump pressure. The axial shift positions can be abbreviated as follows:

• Switch position I: high pump pressure, late adjustment, Fig. 5 . 6
• Switch position II: Low pump pressure, late adjustment, Fig. 11 . 12
• Switch position III: locked adjustment Fig. 9 . 10
• Shift position IV: Low pump pressure, early adjustment, Fig. 13 . 14
• Switch position V: High pump pressure, adjustment to early, Fig. 7 . 8th

The advantage of this adjustability is, in particular, that the inlet orifices 41 and 43 to the respective partial chambers A, B are not completely closed due to the counteracting at high pump pressure and one of the desired setting direction momentum, whereby the pumping power compared to the weaker camshaft torque despite opposite acting camshaft torque can still be used for adjustment. So there are also the times in which opposing acting camshaft moments occur, exploitable for the adjustment, resulting in a quick adjustment. But if the pump power is less than the camshaft moments, the oppositely acting moments are hidden by means of the fully closed openings 41 and 43, so that no return adjustment occurs.

In FIG. 15 shows how the flow of pressure fluid at the respective inner and outer edges PA, PB, BT, AT changes depending on the switching position. Shown dashed are courses at times with a camshaft torque to early and solid at camshaft moments late. By way of example, the line for the inner edge of the first partial cover 51A, PB is explained: For late-cycle camshaft, the flow at the inner edge PB is high to all axial positions, while at moments early on from the switching position I to the switching position II and following switching positions quickly drops to zero.

FIG. 16 shows for the switching positions IV schematically the opening degree of the openings 41, 43 viewed from the respective inner edges PB, PA and outer edges BT, AT in dependence of the switching positions IV and the direction of adjustment. Fully shaded boxes correspond to a fully closed aperture 41, 43, wholly white panels correspond to a fully opened aperture 41, 43 and partially hatched panels correspond to a partially blocked aperture 41, 43.

The previous embodiments related to adjusting method, in which is adjusted predominantly by means of the pressure supplied by the pump P and at the pressure which is generated by camshaft moments, supporting acts in suitable switching positions. In the following, in addition to such a pump mode, a torque mode will now be described in which predominantly the pressure peaks generated by camshaft torques are used for the adjustment, while the pressure provided by the pump P possibly supports the adjustment.

In FIG. 17 is one of the representations of the Figures 5-14 corresponding representation selected to explain an adjustment to late by the use of late-torque. The opening cover 51 is here adjusted by means of the axial position of the valve piston 27 so that upon the occurrence of a late-torque connection of the two sub-chambers A and B on the first and second openings 41, 43 results. In this case, the first openings 41 are wide open, so that again results in a strong Entdrosselung and thus a low risk of air intake. The second openings 43 are opened slightly to set a flow control from the first sub-chamber A. By the late-rotating camshaft torque now a pressure peak is built up, which generates a higher pressure on the different opening ratios of the first and second openings 41, 43 in the first sub-chamber A, as in the second sub-chamber B and thus with displacement of oil from the first Part chamber A in the second sub-chamber B causes a displacement of the wing 67 and thus an adjustment of the camshaft 35 to late. Oil from the pump P, which enters via the third openings 45, supports this adjustment and compensates for leakage losses.

FIG. 18 shows the same axial switching position as FIG. 17 , only here the relative rotational position between the valve piston 27 and the valve housing 29 is changed, since now the camshaft 35 is in a rotational position in which an early torque occurs. Since an adjustment should continue to be late (unchanged axial position of the valve piston 27), this early torque must be hidden in terms of its adjustment. For this purpose, the first partial cover 51A completely blocks the first openings 41. Oil can thus not escape from the second sub-chamber B and there is no adjustment. The complete shut-off prevents a return swing. About fully open second openings 43 and thus greatly de-throttled pump pumped P neutral neutral oil in the first sub-chamber A. This prevents air suction.

The Figures 19 and 20 show the the Figures 18 and 19 corresponding settings, only for the reverse direction to early.

• Schaltstellung I: Pumpen-Modus (OPA), Verstellung nach spät, Fig. 5, 6
• Schaltstellung II: Moment-Modus (CTA), Verstellung nach früh, Fig 19, 20
• Schaltstellung III: Gesperrte Verstellung Fig. 9, 10
• Schaltstellung IV: Moment-Modus (CTA), Verstellung nach spät, Fig 17, 18
• Schaltstellung V: Pumpenmodus (OPA), Verstellung nach früh, Fig 7, 8

A particularly favorable sequence of switching positions can now be constructed by selecting axially successive switching positions as follows:

• Switch position I: pump mode (OPA), adjustment after late, Fig. 5 . 6
• Shift position II: torque mode (CTA), shift to early, Fig. 19 . 20
• Switch position III: locked adjustment Fig. 9 . 10
• Shift position IV: torque mode (CTA), shift to late, Fig. 17 . 18
• Switching position V: pump mode (OPA), adjustment to early, Fig. 7 . 8th

Thus, it is possible to set either a pump mode or a torque mode, depending on the presence of either a dominant pressure of the pump P or dominant camshaft moments for the camshaft adjustment. In FIG. 21 is again shown for this sequence of switching positions, such as the flow of pressure medium at the respective control edges, ie inner and outer edges PA, PB, AT, BT depending on the axial position of the valve piston 27 and the valve housing 29, so the switching positions IV changes.

FIG. 22 shows for the switching positions IV schematically the opening degree of the openings 41, 43 viewed from the respective inner edges PB, PA and outer edges BT, AT in dependence of the switching positions IV and the direction of adjustment. Fully shaded boxes correspond to a fully closed aperture 41, 43, wholly white panels correspond to a fully opened aperture 41, 43 and partially hatched panels correspond to a partially blocked aperture 41, 43.

The previous illustrations and examples related to a variant which is particularly suitable as a so-called central valve design, ie, a control valve for controlling the supply and discharge of pressure medium to the sub-chambers is arranged centrally in a camshaft. In the following, a variant is shown in which the control valve is arranged outside the camshaft is and cooperates with a rotary transformer, which controls together with the control valve and the camshaft, a control device 20 for controlling the supply and removal of pressure medium to the sub-chambers. In this case, the rotary transformer assumes the function of adaptation to the respective camshaft moments, while the setting for an advance, retard or hold is adjusted by the control valve. This can be realized, for example, via the following designs:

FIG. 23 shows in a split state, a camshaft 35 and designed as a bearing shell for the camshaft 35 rotary transformer in a perspective view. In addition, a control valve 101 is shown in a longitudinal section. The camshaft 35 has concentric inner channels which, as indicated, correspond once to the first sub-chamber A and once to the second sub-chamber B. To the inner channels lead through the camshaft wall from the outside first openings 41, which correspond to the first sub-chamber A and second openings 43, which correspond to the second sub-chamber B. In the installed state, the rotary transformer 103 surrounds the camshaft 35 in the region of the dashed lines. On the inside of the rotary transformer 103, an opening cover 51 is arranged, which forms an interrupted, radially inner bearing surface. It is interrupted by recesses 105. The opening cover 51 could for example be milled or be formed by an example soldered insert. Depending on a rotation angle of the rotary camshaft 35 and the non-rotating rotary transformer 103, the first openings 41 and second openings 43 are now covered or released by the opening cover 51. Since the rotational position of the camshaft 35 is synchronous with the camshaft moments, thereby an inflow or outflow of pressure medium through the first openings 41 and second openings 43 and thus the inflow and outflow of pressure medium in the sub-chambers A, B in response to the acting camshaft torque be set.

The illustration of the control valve 101 in longitudinal section illustrates the assignment to a pump opening 109P and to the partial chamber openings 109A, 109B in the valve housing 29. These openings are released or closed by the arranged in the valve housing 29, axially displaceable valve piston 27 via the control edges KAT, KPA, KBT, KPB at the Teilkammeröffnungen 109A, 109B and the control edges P1, P2, P3, P4 at the pump port 109P. These control edges are formed by projections or noses on a cylindrical surface of the valve piston 27, wherein each have a projection or nose a pair of control edges. Compared with valve designs in the prior art, by a conventional hydraulic control of a camshaft adjustment, the present embodiment, in particular the peculiarity of the additional control edges P1, P2, P3, P4. In cooperation with the first and second openings 41, 43 in the camshaft 35 and the opening cover 51 in the rotary transformer 103 now various switch positions depending on the engine operating condition, in particular the engine oil pressure and the strength of the camshaft torques can be adjusted. This will be explained in more detail in the following figures.

The Figures 24-28 show for the in FIG. 23 shown variant of the rotary transformer 103 is a schematic representation of the control of pressure medium as a function of the camshaft torque by means of rotary transformer, camshaft and control valve. In the upper area, the control valve 101 is again shown in a longitudinal section. The valve piston 27 of the control valve 101 is determined in its axial position by a magnet 21. A percentage here shows the degree of energization of the electromagnet 21 and thus the degree of axial displacement of the valve piston 27. There are 5 switch positions shown below, at 100%, 75%, 50%, 25% and 0% current. Of course, other values for the energization can be possible here. Under the control valve 101, stator and rotor of a camshaft adjuster 11 with partial chambers A, B are shown schematically on the left as in earlier figures. To the right is shown a longitudinal section through part of the camshaft 35 and the rotary transmitter 103 arranged thereabove, which leads through the first and second openings 41, 43. Below this area is shown schematically in the circumferential direction unwound form, so the overlap of the opening cover 51 with the first and second openings 41, 43 is recognizable. To this end, to the right of it, the output of the camshaft torques and their orientation to early or late is shown in synchronous representation.

FIG. 24 shows now a first switching position at 100% energization of the electromagnet 21 and thus at a first axial position of the valve piston 27. This switching position corresponds to an adjustment in the late direction, according to the relative rotational position of the rotary transformer 103 and the camshaft 35 an angular position for a camshaft torque to is set late. The dashed and dotted lines schematically show the flow directions of the pressure medium. Pressure fluid passes via the pump opening 109P in the valve housing 29 via the second openings 43 into the second sub-chamber B. At the same time, pressure medium is discharged from the first sub-chamber A via the first openings 41 and the sub-chamber opening 109A to the tank. The cross sections of the apertures released via the control edges P1, P2 and KAT are large, that is, there is a strong Entdrosselung. On the one hand, this prevents harmful air intake and, on the other hand, allows quick adjustment. In FIG. 25 is the corresponding picture as in FIG. 24 shown, only the rotational position of the camshaft 35 has now changed so that an early torque occurs. Unlike the late-torque, which in FIG. 24 the adjustment direction supported late, the early torque leads to a desired adjustment opposing force and thus to a delay. This is prevented by the fact that the flow from the second sub-chamber B is now closed via the control edge P4 and thus no adjustment can take place, since no pressure medium from the sub-chamber B can be displaced.

The switching position of Figures 24 and 25 Thus corresponds to a retardation and that in the pump mode, since mainly the pressure of the pressure medium supplied by a pump P is used for adjustment. However, should an operating condition be present in which the pressure is low and insufficient for rapid adjustment, the valve piston 27 can move into its next axial position Position are moved, in which the torque mode is set for an adjustment to late. This is based on the Figures 26 and 27 explained.
The Figures 26 and 27 show the one Figures 24 and 25 corresponding image, now only 75% of the electromagnet is energized and the valve piston 27 thus assumes a new axial switching position in the direction of the magnet 21. This switching position also causes a retardation. Now, however, results in the occurrence of a late-torque connection of the sub-chambers A, B, so that is built by the late-torque pressure in the first sub-chamber A, whereby pressure medium from the first sub-chamber A is pushed into the second sub-chamber B this leads to the desired adjustment. When an early torque occurs, however, again the flow from the second sub-chamber B is blocked, so that no adjustment can take place.

In FIG. 28 is a switching position at 50% energization of the electromagnet 21 shown. In this switching position, the angular position of the camshaft 35 is held, ie there is no adjustment. This is achieved in that, when a late-torque occurs, an outflow from the first sub-chamber A is blocked, as in FIG FIG. 28 shown. If an early torque, not shown, the first and second openings 41, 43 would come to rest again so that a flow from the second sub-chamber B would be blocked, so that no adjustment is possible in this case.

According to the Figures 24-27 is in a switching position of 25% energization a torque mode for an early adjustment and a switching position of 0%, a pump mode for an early adjustment adjustable, with correspondingly interchangeable release or blocking of the openings. By simply selecting the axial position of the valve piston 27, it is thus possible for the first time to set a pump mode or a torque mode, that is, to select an OPA method or a CTA method for the adjustment, depending on the operating state of the internal combustion engine. This adaptability thus achieves a particularly fast adjustment overall. in addition comes the strong de-throttling, which also ensures rapid adjustment and additionally prevents air intake.

In FIG. 29 a second variant is shown, the representation of FIG. 23 However, the opening cover 51 is now limited by three groove-like recesses 105. In addition, a locking mechanism 121 is provided in the rotor 65 of the camshaft adjuster 11, which can be designed as a locking pin lock in a manner not shown in a locking link of the stator 63 by pressure of a spring. This locks an adjustment. An unlocking is effected by a hydraulic pressure against the spring, wherein the locking mechanism 121 pressure medium is supplied. This pressure medium is now supplied via a separate locking feed line 125, which corresponds to locking openings 123 in the camshaft 35. The locking openings 123 are arranged in the axial direction at the same height as the second openings 43 but circumferentially spaced from the second openings 43. Furthermore, two locking openings 123 are arranged in the circumferential direction between each two second openings 43. The first openings 41 and the second openings 43 are formed in this variant as axially extending slots. The following figures explain the function.

The Figures 30-35 show the various switching positions of the valve piston 27 and the relative orientation of the first and second openings 41, 43 and the locking holes 123 to the opening cover 51. The illustration corresponds to the illustration of Figures 24-28 However, wherein the described second variant of the first and second openings 41, 43 and the opening cover 51 and the additional locking mechanism 121 is shown. The second openings 43 are in this embodiment now left and the first openings 41 right.

FIG. 30 shows a switching state with 0% energization of the magnet 21, so that the valve piston 27 is set in its axial normal position. This is the case, for example, when the internal combustion engine is turned off and the subchambers A, B are not under pressure. The wing 67 of the rotor 65 would have to strike in the figure on the left of the stator, ie in an adjustment maximum late. For the sake of simplicity and to illustrate the partial chambers A, B, however, the same position of the wing 67 is always shown in each of the figures regardless of the adjustment state. The switching position corresponds to a retardation, wherein in FIG. 30 the case of the occurrence of a late torque is mapped. In this rotational position, one of the second openings 43 corresponds to one of the recesses 105, which is supplied with pressure medium from the pump P via the pump opening 109P of the valve housing 29. Thus, the second sub-chamber B is supplied with pressure medium. A discharge of pressure medium from the first sub-chamber A is possible via one of the first openings 41, which corresponds to the recess 105, which is connected to the partial chamber opening A of the valve housing. About the released by the valve piston 27 in this axial position partial chamber opening A, the pressure medium is then passed to the tank. An adjustment does not take place in spite of these settings in this case, because yes, the wing 67 is already on the late stop.

In this basic position, the locking mechanism 121 is locked, so that it does not cause a disturbing rattling at an engine start because of the then occurring camshaft moments and the lack of pressure in the sub-chambers A, B, because the wing 67 alternately strikes the stator 63 alternately left and right.

One of the locking openings 123 corresponds to one of the recesses 105, which corresponds to the partial chamber opening 109B of the valve housing 29. Due to the position of the valve piston 27, however, this partial chamber opening 109B is not supplied with pressure or is shut off. Thus, also a pressure increase, which after engine start e.g. occurs through an air column pushed by the oil, do not reach the locking mechanism 121. Unintentional unlocking is not possible.

FIG. 31 shows one of FIG. 30 corresponding picture, only that has changed the rotational position of the camshaft 35 and now an early torque occurs.

During operation with filled sub-chambers A, B now this early torque would not be able to effect an adjustment in the direction of early, since the flow from the sub-chamber B is locked. So it does not come to a return swing. In the non-pressurized, locked basic position, the adjustment position is also retained due to the lock. The lock does not solve either, since the locking mechanism 121 remains unpressurized.

FIG. 32 now shows a switching position in which the valve piston 27 has moved axially in accordance with an energization of the magnet 21 with 25% of the maximum current. The case of the occurrence of a late-torque is shown. This switching position corresponds to the moment mode while the to the Figures 30 and 31 discussed switch position corresponds to the pump mode. The valve piston 27 now releases a connection of the partial chamber opening 109A with the pump opening 109P. The pump port 109P corresponds to the second sub-chamber B, while the sub-chamber port 109A corresponds to the first sub-chamber A. Thus, a connection of the sub-chambers A, B, in a sense a short circuit, made.

During operation, in filled sub-chambers A, B the following applies: When a late-torque, so a moment in the desired adjustment direction, the wing 67 exerts pressure on the first sub-chamber A and is by shifting pressure medium from the first sub-chamber A. moved into the second sub-chamber B towards late. In FIG. 33 the rotational position is shown when an early torque occurs. The second sub-chamber B is blocked by the position of the valve piston 27, so that no pressure medium can be ejected. The acting on the second sub-chamber B pressure of the early torque thus does not lead to an adjustment.

Shortly after the engine start, with still unfilled sub-chamber A, B, the locking mechanism 12 is still locked and is also kept unpressurized by a lock as in the 0% switching position, ie it remains locked and an adjustment remains locked.

FIG. 34 now shows a den Figures 30-33 corresponding image, wherein now an axial switching position of the valve piston 27 is set at 75%. This is again an adjustment of the moment mode, but now for an adjustment towards early. It applies, with appropriate permutation, the same mechanism for adjustment by taking advantage of the camshaft moments as to Figures 32 and 33 described, except for the fact that now receives the locking mechanism 121 pressure, since the Teilkammeröffnung 109 B of the valve housing 29 is now released from the valve piston 27 and thus pressure medium to the locking mechanism 121 passes. As a result, he is pushed back against his pen and unlocked. An adjustment is now possible when an early torque occurs in what FIG. 35 is shown. The release of the locking mechanism 121 happens after an engine start but only when sufficient pressure is present so that it does not come to an unwanted unlocking.

Not shown in detail is the axial switching position at 100% current, which corresponds to the pump mode for an early adjustment and similar to the late-adjustment of the pump mode as with the Figures 30 and 31 described works. The five axial shift positions and the camshaft torque-dependent rotational position can be summarized in a hydraulic circuit diagram, which in FIG. 36 is shown. Schematically, the control valve 101 is shown, wherein in five juxtaposed squares, the five switching positions of the valve piston 27 are shown, the 0%, 25%, 50%, 75% and 100% energization of the magnet 21 correspond. The partial chamber openings 109A, 109B, pump opening 109P, and outflow to the tank T of the valve housing 29 are fixed and can by the various compounds, shown as an arrow, and closures, shown as "T", occupied by the corresponding square of the desired switching position is moved to the terminals. The relative rotational position of the camshaft 35 and the Drehübertragers 103 are also schematically represented by an axial positional shift, wherein the coupling is imaged to the camshaft torques by guiding a guide pin 127 in a rectangular wave guide groove 129 and the guide pin 127 each after occurrence of an early torque or late torque, the first or second rotational position D1, D2 activated. Guide pin 127 and guide groove 129 are therefore only fictitious for illustration. The two rotational positions D1, D2 are shown in two juxtaposed rectangles and, as stated, transformed into an axial displacement, in order to better map the circuit logic. Here, too, arrows then show the interconnected connections. The picture thus shows just an occurrence of an early torque (guide pin 127 in a right-hand groove portion of the guide groove 129) and a retardation in the pump mode. The second sub-chamber B is blocked for an expiry, so it is not adjusted. With the occurrence of a late-torque, the rotational position D2 would be activated, whereby pressure is applied to the second sub-chamber B and at the same time the first sub-chamber A is opened to the tank. It then takes an adjustment to late.

reference numeral

1

internal combustion engine

2

crankshaft

3

piston

4

cylinder

5

traction drive

6

intake camshaft

7

exhaust

8th

cam

9

Inlet gas exchange valve

10

Auslassgaswechselventil

11

Phaser

12

Rotary valve

20

control device

21

magnet

23

magnetic piston

25

twist

27

plunger

29

valve housing

31

Return spring

33

axial bearing

35

camshaft

41

first openings

43

second openings

45

third openings

51

opening cover

51A

first part cover

51B

second part cover

52

crown pips

53

Valve piston surface

63

stator

65

rotor

67

wing

69

pressure chamber

71

first oil channel

73

second oil channel

101

control valve

103

Rotary joint

105

recesses

109P

pump port

109A

Partial chamber opening to the partial chamber A

109B

Partial chamber opening to partial chamber B

121

locking mechanism

123

locking opening

125

locking feed

127

guide pin

129

guide

A

first compartment

B

second sub-chamber

P

Hydraulic pump

T

tank

PA

Inner edge of the second sub-cover 51B

PB

Inner edge of the first partial cover 51A

AT

Outer edge of the second sub-cover 51B

BT

Outer edge of the first sub-cover 51A

P1, P2, P3, P4

Pump control edges

KAT, KPA, KBT, KBA

Sub-chamber control edges

D1, D2

rotational positions

Claims (9)

1. Camshaft adjuster (11) for a camshaft (35) which serves to actuate cylinder valves (12) of an internal combustion engine, wherein retardation torques in the direction of retarded cylinder valve opening times are imparted back to the camshaft adjuster (11) by the camshaft (35) when cams are running on, and oppositely directed advance torques in the direction of advanced cylinder valve opening times are imparted back to the camshaft adjuster (11) by the camshaft (35) when cams are running off,

   • having a pressure chamber (69) and having an adjusting means (67) arranged in the pressure chamber (69),

   • wherein the adjusting means (67) divides the pressure chamber (69) into a first chamber part (A) and a second chamber part (B),

   • wherein pressure medium can be supplied to the first and the second chamber part (A, B) and pressure medium can be discharged from the first chamber part (A) and second chamber part (B),

   • such that the adjusting means (67) can be moved by a pressure difference between the first chamber part (A) and second chamber part (B), resulting in a rotation of the camshaft (35),

   • wherein, when a relatively high pressure prevails in the first chamber part (A), the camshaft (35) is rotated in the direction of advanced cylinder valve opening times, and when a relatively high pressure prevails in the second chamber part (B), the camshaft (35) is rotated in the direction of retarded cylinder valve opening times,

   • and wherein the supply and discharge of pressure medium can be controlled by means of a control device (20),

   • wherein a torque mode or a pump mode can be selectively set by means of the control device (20),

   • wherein in the torque mode, predominantly camshaft torques are utilized to build up pressure in the first chamber part (A) or in the second chamber part (B),

   • whereas in the pump mode, the pressure build-up in the first chamber part (A) or in the second chamber part (B) is realized predominantly by means of pressure medium provided by a pressure medium pump (P).
   characterized in that

   • the control device (20) comprises a control valve (101) and a rotary transmitter (103) arranged on the camshaft (35), wherein pressure medium can be conducted to and discharged from the first chamber part (A) through first orifices (41) in the camshaft (35), and pressure medium can be conducted to and discharged from the second chamber part (B) through second orifices (43) in the camshaft (35), by means of the control valve (101) and the rotary transmitter (103), wherein an orifice cover (51) is arranged in the rotary transmitter (103) such that the first orifices (41) and second orifices (43) are opened up or blocked as a function of the rotary angle of the camshaft (35).
2. Camshaft adjuster (11) according to Claim 1, in which the orifice cover (51) is formed by the inner side of a bearing shell in which the camshaft (35) is mounted, wherein the orifice cover (51) is made discontinuous by recesses (105) such that the first orifices (41) and second orifices (43) are opened up in the region of the recesses (105), whereas said orifices are blocked in the region of the orifice cover (51).
3. Camshaft adjuster (11) according to Claim 1, in which the pump mode or the torque mode can be set by means of an axial displacement of a valve piston (27) arranged in a valve housing (29) of the control valve (101).
4. Camshaft adjuster (11) according to Claim 3, in which the valve housing (29) has a pump orifice (109P) by means of which the supply of pressure medium either to the first chamber part (A) or to the second chamber part (B) can be set such that in each case either the first chamber part (A) or the second chamber part (B) is pressurized, wherein the flow of pressure medium out of the first chamber part (A) or the second chamber part (B) can be set by means of chamber part orifices (109A, 109B) in the valve housing (29).
5. Camshaft adjuster (11) according to Claim 4, in which the valve piston (27) has, axially spaced apart from one another, two pairs of chamber part control edges (KAT, KPA, KBT, KPB) such that, by means of said chamber part control edges (KAT, KPA, KBT, KPB), the chamber part orifices (109A, 109B) can be opened up and closed off by means of the axial position of the valve piston (27), wherein furthermore, two pairs of pump control edges (P1, P2, P3, P4) are formed axially between the chamber part control edges (KAT, KPA, KBT, KPB), by means of which pump control edges the inflow of pressure medium from a pressure medium pump (P) via the pump orifice (109P) can be controlled.
6. Camshaft adjuster (11) according to Claim 1, in which, for the relative axial position of the valve piston (27), five switching positions can be set, wherein

   • in a first position, the pump mode is set for an adjustment of the camshaft (35) in the direction of retarded cylinder valve opening times,

   • in the second, axially subsequent switching position, the torque mode is set for an adjustment of the camshaft (35) in the direction of retarded cylinder valve opening times,

   • in the third, axially subsequent switching position, a camshaft adjustment is blocked,

   • in the fourth, axially subsequent switching position, the torque mode is set for an adjustment of the camshaft (35) in the direction of advanced cylinder valve opening times, and

   • in the fifth, axially subsequent switching position, the pump mode is set for an adjustment of the camshaft (35) in the direction of advanced cylinder valve opening times.
7. Camshaft adjuster (11) according to Claim 3, in which a locking mechanism (121) is provided by means of which the camshaft adjuster (11) is mechanically blocked in a locking position so as to be prevented from being adjusted, wherein the locking mechanism (121) can be hydraulically unlocked by the pressure medium, and wherein a supply of pressure medium to the locking mechanism (121) is connected such that the locking mechanism (121) unlocks only when the valve piston (27) is in an axial switching position which corresponds to an adjustment in the direction of advanced cylinder valve opening times.
8. Camshaft adjuster (11) according to Claim 6, in which the supply corresponds to locking orifices (123) in the camshaft (35), which locking orifices are arranged at the same level as the second orifices (43) in the axial direction but spaced apart from the second orifices (43) in the circumferential direction.
9. Camshaft adjuster (11) according to Claim 7, in which two locking orifices (123) are arranged between in each case two second orifices (43).

Images