EP2504535B1 - Device for variably adjusting the control times of gas exchange valves of an 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, there are high levels Phase adjustment speeds desirable. Furthermore, in the context of consumption reduction measures, an ever lower pressure medium requirement is required to be able to design the pressure medium pump of the internal combustion engine smaller or to be able to reduce the delivery 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 slowed the opening of the gas exchange valves and accelerated during closing. 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 having at least one drive means, at least one camshaft with cams, at least one hydraulically actuable adjusting device for adjusting the relative rotational angle, between the drive means and the camshaft, at least one hydraulic fluid supply means for acting on the adjusting device and at least a positive control device, by the hydraulic actuation of the adjusting device in response to the absolute angle of rotation of the camshaft and / or the cam is 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 of opposite camshaft moments.

The WO 2008/067935 A2 shows 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, with an adjusting means with working chambers, an adjusting device and a hydraulic system, wherein arranged in the pressure oil inlet of the hydraulic system, a first check valve and between the working chambers, a second check valve is.

The EP 1 783 334 A1 shows a camshaft adjuster, in which a first pair of working chambers by means of a CTA method and a second pair of working chambers are operated simultaneously by means of an OPA method.

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, wherein at a high Phasenverstellgeschwindigkeit a low oil consumption should be necessary.

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 with incoming cams late torques in the direction of later cylinder valve opening times and expiring cam opposite early torques in the direction early cylinder valve opening times react on the 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 pressure medium provided, said Control means comprises a valve housing arranged in a valve piston, wherein the valve piston relative to the valve housing is rotatable and axially displaceable, wherein axial relative displacement of the valve piston relative to the valve housing, the torque mode or the pump mode is adjustable, while relative rotation of the valve piston over the valve housing, the supply and removal of the pressure medium to the sub-chambers (A, B) is controllable.

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 recognition that respective advantages of the OPA and CTA methods depend on an operating state of the Combustion engine can be combined with each other favorably. In operating conditions in which a high pump pressure of the pressure medium pump is available, the pump mode, ie an OPA method is favorably chosen, while at low pump pressures but high camshaft torques, 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 valve housing arranged in a valve piston, wherein the valve piston relative to the valve housing is rotatable and axially displaceable, by axially relative displacement of the valve piston relative to the valve housing the torque mode or the pump mode is adjustable while by relative rotation of the Valve piston relative to the valve housing, the supply and removal of the pressure medium to the sub-chambers is controllable.

The switching positions for the pump or torque mode are thus realized in a structurally simple manner by an axial displacement of the valve piston relative to the valve housing. In a respective axial switching position then the actual regulation of the adjustment, ie the supply and removal of pressure medium to the sub-chambers by means of a rotation of the valve piston relative to the valve housing is possible. Advantageously, the valve piston is moved relative to a fixed cylinder head for the axial displacement, for example by means of a magnet and a return spring, while the relative rotation is implemented by the valve housing, which rotates approximately with the camshaft. This embodiment is particularly in a preferred central valve design used, in which the control valve of the control device formed from the valve piston and the valve housing is arranged centrally in the camshaft adjuster and this further preferably simultaneously connects as a screw with the camshaft. In a further preferred embodiment, the return spring of the valve piston is roller-mounted as a compression spring relative to the valve housing or connected as a tension spring directly or indirectly with the magnet.

Preferably, first openings and second openings are arranged distributed in the valve housing around the circumference of the valve housing, wherein the first openings with the second sub-chamber and the second openings correspond to the first sub-chamber and wherein an opening cover is formed by the surface of the valve piston, so that depending on axial position and angular position of the valve piston relative to the valve housing, the first openings and second openings are at least partially closed by the opening cover. The opening cover is thus e.g. a radially opposite to the rest of the valve piston body further outside surface which is adjacent to the valve housing.

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. More preferably, the port cover may be configured to be adjusted for asymmetric displacement of camshaft torques relative to the zero line. Such asymmetric displacement occurs in particular by a friction torque, which acts on the camshaft in the direction of late regardless of the angle. As a result, the approximately sinusoidal curve of the camshaft profile is thus shifted by an amount corresponding to the friction torque as a whole. Thus, it may be advantageous to adapt the respective local widths of the opening cover to the now shortened or extended effective times of an early or late torque. For example, would then an opening coverage shown "unwound" no longer correspond to a symmetrical rectangular curve with the same length maxima and minima phases, but for the maxima and minimum phases would each result in different lengths.

This arrangement makes it possible in particular, without further constructive measures such. Check valves alone from the geometric arrangement of valve body and valve piston to perform a tuned to the camshaft moments adjustment. Since the camshaft moments occur over the arrangement of the cams in a fixed geometric phase position, by the corresponding arrangement of the openings and opening cover, for example. be achieved that in a CTA process mode verstellrichtige moments exploited via shared openings and false adjustment moments on locked openings are hidden.

The opening cover is preferably formed from a first partial cover for the first openings and a second partial cover for the second openings, wherein the first partial cover and the second partial cover each have an outer edge lying axially on the valve piston and an inner inner edge lying inside, wherein the inner edges are in the circumferential direction have an approximately crown-like profile with circumferentially changing axial position.

The inner edges thus extend in the circumferential direction, for example, zigzag-like, crown-like or in the form of a rectangular curve, ie the inner edges extend in sections at a first axial position and in further sections in an axially spaced position. This makes it possible, with the opening cover depending on the relative rotation of the valve piston and the valve housing, the openings in the valve body to release or block completely or partially. This release or blocking is, as stated above, geometrically coupled to the phase position of the camshaft moments.

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 early 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 late 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 moments, a retardation in shift position two and an advance in shift position four. The middle position, switch position three, can be used to block the adjustment.

• Vorzugsweise ist in der ersten Schaltstellung bei Auftreten von Spät-Drehmomenten eine relative Winkellage von Ventilgehäuse und Ventilkolben so eingestellt, dass die ersten Öffnungen durch die Öffnungsabdeckung überwiegend für einen Zulauf von Druckmittel von der Druckmittelpumpe freigegeben sind,
• während die zweiten Öffnungen für einen Ablauf von Druckmittel geöffnet sind wobei bei Auftreten von Früh-Drehmomenten eine relative Winkellage von Ventilgehäuse und Ventilkolben so eingestellt ist, dass die ersten Öffnungen durch die Öffnungsabdeckung für einen Zulauf von Druckmittel von der Druckmittelpumpe freigegeben sind, während die zweiten Öffnungen für einen Zulauf von Druckmittel von der Druckmittelpumpe und gleichzeitig für einen Ablauf von Druckmittel freigegeben sind.

These five switch positions are preferably to be realized as follows:

• Preferably, in the first switching position when late torques occur, a relative angular position of the valve housing and the valve piston is adjusted such that the first openings through the opening cover are released predominantly for an inflow of pressure medium from the pressure medium pump,
• while the second openings are open for a discharge of pressure medium, wherein upon occurrence of early torques, a relative angular position of the valve housing and the valve piston is adjusted so that the first openings are released through the opening cover for a supply of pressure medium from the pressure medium pump, while the second Openings for an inlet of pressure medium from the pressure medium pump and are released at the same time for a drain of pressure medium.

Preferably, in the second switching position at the occurrence of early torques, a relative angular position of the valve housing and valve piston adjusted so that the second openings released by the opening cover mainly for an inlet of pressure medium from the first sub-chamber and the first openings for a drain of pressure medium the first sub-chamber are open in the second sub-chamber, wherein at late torque occurrence a relative angular position of the valve housing and the valve piston is adjusted so that the second openings are blocked by the opening cover, while the first openings for an inlet of pressure medium from the pressure medium pump are largely open

Preferably, in the third switching position, a relative angular position of the valve housing and the valve piston is adjusted so that the first openings are blocked by the opening cover in the occurrence of early torques and the second openings through the opening cover when late torques occur.

Preferably, in the fourth switching position when late torques occur, a relative angular position of the valve housing and valve piston is set such that the first openings through the opening cover release predominantly for an inlet of pressure medium from the second sub-chamber and the second openings for a discharge of pressure medium the second sub-chamber are opened in the first sub-chamber, wherein upon occurrence of early torques, a relative angular position of the valve housing and the valve piston is adjusted so that the first openings through the opening cover are locked while the second openings are largely opened for an inlet of pressure medium from the pressure medium pump.

Preferably, in the fifth switching position at the occurrence of early torques, a relative angular position of the valve housing and the valve piston is adjusted so that the second openings are released by the opening cover mainly for an inlet of pressure medium from the pressure medium pump, while the first openings for a drain of pressure medium wherein, when late torques occur, a relative angular position of the valve housing and the valve piston is adjusted so that the first openings are released through the port cover for an inlet of pressure medium from the pressure medium pump and at the same time for a drain of pressure medium, while the second openings are open for an inlet of pressure medium from the pressure medium pump.

The characteristic given for the above switching positions that an opening is largely released means that its predominant cross-section is not blocked by the opening cover. This corresponds to a strong dethrottling. This embodiment is not absolutely necessary but merely a preferred embodiment, in particular with the advantage that due to the largely unimpeded pressure medium passage does not exist the risk of air suction. As a result, a hydraulic rigidity is ensured and prevents the generation of disturbing noises. Unlike conventional systems in which usually an axial displacement of a control piston an opening steadily increasing in accordance with the axial actuating movement is released, allows the rotation of the opening cover on or from a relatively large opening in the valve housing, the sudden release of a large cross section and thus the desired de-throttling.

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

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

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 variably setting the timing of gas exchange valves 9,10 of 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 a first partial cover 51A at one axial end of the valve piston 27 and a second partial cover 51B at the opposite end. Both partial covers 51 A, 51 B are crown-like, 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 51 A 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 51 A, 51 B is jagged rectangular. In each case, a crown 52 of a partial cover 51A, 51 B is oriented in the circumferential direction 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 moments greater than zero correspond to a moment in the direction an early adjustment, ie in a direction in which there is an earlier opening of the cylinder valves 12. 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, Wing and supply channels, which are not shown here for 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 partial cover 51A largely releases the first openings 41 via the inner edge PB, so that pressurized oil from a pump P passes through the third openings 45 in the valve housing 29 to the second partial chamber B. 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 camshaft moment. 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 via the wide-open, as strongly dethrottled first Öffnunegn 41 in the second sub-chamber B. As a result a very fast adjustment of the camshaft 35. In a similar manner, a quick adjustment in the direction of early causes ..

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 released by the first part of the cover 51 A little, while the second openings 43 are wide open to the pressure supply from the pump P. 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 thereby additionally utilized the corresponding camshaft torques. 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 characters 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. If, however, the available pressure of the pump P is not high, in particular significantly lower than the pressure exerted by camshaft torques, an adapted OPA method can be set by selecting further switching 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 it is also the times in which counteracting 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. As an example, the line for the inner edge of the first part of the cover 51 A, PB is explained: When the camshaft moments late, the flow at the inner edge PB is high to all axial positions, while at moments early from the shift position I to the shift position II and following Switch 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 the first sub-cover 51 A completely closes off 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 are completely locked Opening 41, 43, completely white fields correspond to a fully opened opening 41, 43 and partially hatched areas correspond to a partially blocked opening 41, 43rd

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

A

first compartment

B

second sub-chamber

P

Hydraulic pump

T

tank

PA

Inner edge of the second partial cover 51 B

PB

Inner edge of the first partial cover 51A

AT

Outer edge of the second partial cover 51 B

BT

Outer edge of the first sub-cover 51A

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),

   • 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 a pressure medium provided by a pressure medium pump (P),

   characterized in that
   the control device (20) comprises a valve piston (27) which is arranged in a valve housing (29), wherein the valve piston (27) is rotatable and axially displaceable relative to the valve housing (29), wherein the torque mode or the pump mode can be set by means of axial relative displacement of the valve piston (27) with respect to the valve housing (29), whereas the supply and discharge of pressure medium to and from the chamber parts (A, B) can be controlled by means of relative rotation of the valve piston (27) with respect to the valve housing (29).
2. Camshaft adjuster (11) according to Claim 1, in which first orifices (41) and second orifices (43) are arranged in the valve housing (29) so as to be distributed over the circumference of the valve housing, wherein the first orifices (41) correspond with the second chamber part (B) and the second orifices (43) correspond with the first chamber part (A), and wherein the surface (53) of the valve piston (27) forms an orifice cover (51) such that the first orifices (41) and second orifices (43) can be at least partially closed off by the orifice cover (51) in accordance with the axial position and angular position of the valve piston (27) relative to the valve housing (29).
3. Camshaft adjuster (11) according to Claim 2, in which the first orifices (41) and the second orifices (43) are arranged relative to one another on the circumference at an angular interval, in each case spaced apart uniformly, and arranged in the correct phase with respect to the orifice cover (51), such that a relative rotation of the valve piston (27) with respect to the valve housing (29) by the angular interval leads to a geometrically identical arrangement.
4. Camshaft adjuster (11) according to Claim 2, in which the orifice cover (51) is formed from a first cover part (51A) for the first orifices (41) and a second cover part (51B) for the second orifices (43), wherein the first cover part (51A) and the second cover part (51B) have in each case an edge (AT, BT) situated axially at the outside on the valve piston (27) and an axially inner edge (PA, PB), wherein the inner edges have an approximately crown-like profile in the circumferential direction with an axial position which alternates along the circumference.
5. 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 advanced 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 retarded 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.
6. Camshaft adjuster (11) according to Claim 4 and 5, in which,

   • in the first switching position, upon the occurrence of retardation torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the first orifices (41) are predominantly opened up by the orifice cover (51) for a supply of pressure medium from the pressure medium pump (P),

   • while the second orifices (43) are open for a discharge of pressure medium, wherein,

   • upon the occurrence of advance torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the first orifices (41) are opened up by the orifice cover (51) for a supply of pressure medium from the pressure medium pump (P),

   • while the second orifices (43) are opened up for a supply of pressure medium from the pressure medium pump (P) and simultaneously for a discharge of pressure medium.
7. Camshaft adjuster (11) according to Claim 4 and 5, in which,

   • in the fourth switching position, upon the occurrence of retardation torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the first orifices (41) are predominantly opened up by the orifice cover (51) for a supply of pressure medium from the second chamber part (B) and,

   • the second orifices (43) are open for a discharge of pressure medium from the second chamber part (B) into the first chamber part (A),

   • wherein, upon the occurrence of advance torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the first orifices (41) are blocked by the orifice cover (51),

   • while the second orifices (43) are substantially opened up for a supply of pressure medium from the pressure medium pump (P).
8. Camshaft adjuster (11) according to Claim 4 and 5, in which,

   • in the second switching position, upon the occurrence of advance torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the second orifices (43) are predominantly opened up by the orifice cover (51) for a supply of pressure medium from the first chamber part (A) and

   • the first orifices (41) are open for a discharge of pressure medium from the first chamber part (A) into the second chamber part (B),

   • wherein, upon the occurrence of retardation torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the second orifices (43) are blocked by the orifice cover (51),

   • while the first orifices (41) are substantially opened up for a supply of pressure medium from the pressure medium pump (P).
9. Camshaft adjuster (11) according to Claim 4 and 5, in which,

   • in the fifth switching position, upon the occurrence of advance torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the second orifices (43) are predominantly opened up by the orifice cover (51) for a supply of pressure medium from the pressure medium pump (P),

   • while the first orifices (41) are open for a discharge of pressure medium, wherein,

   • upon the occurrence of retardation torques, a relative angular position of the valve housing (29) and valve piston (27) is set such that the first orifices (41) are opened up by the orifice cover (51) for a supply of pressure medium from the pressure medium pump (P) and simultaneously for a discharge of pressure medium,

   • while the second orifices (43) are opened up for a supply of pressure medium from the pressure medium pump (P).

Images