EP2238319B1 - Device for variably adjusting the control times of gas exchange valves of an internal combustion engine - Google Patents

Abstract

A device for variably adjusting the control times of gas exchange valves of an internal combustion engine. The device has a driving element, an output element, at least one pressure chamber, at least one mechanism limiting the angle of rotation, and a pressure accumulator. A phase angle between the output and driving element is changed by delivering or discharging pressure medium to or from the pressure chambers. The mechanism limiting the angle of rotation has a receiving member and an engaging element to which a force is applied towards the receiving member. When locked, where the engaging element engages into the receiving member, the mechanism limiting the angle of rotation limits the phase angle of the output element relative to the driving element at least to an angular spread. The mechanism limiting the angle of rotation can be unlocked by applying pressure medium to the receiving member.

Description

Field of the invention

The invention relates to a device for variably setting the timing of gas exchange valves of an internal combustion engine with a drive element, an output element, at least one pressure chamber, at least one rotation angle limiting device and at least one pressure accumulator, wherein a phase position between the output element and the drive element by pressure medium supply to or pressure fluid removal from the Pressure chamber is variable within a maximum possible angular range, each rotational angle limiting device in a locked state, the phase angle at least an angular range, smaller than the maximum possible angular range limited, wherein the rotational angle limiting device can be transferred by pressurizing a control line in an unlocked state, and wherein the Pressure accumulator communicates at least temporarily with the control line during operation of the internal combustion engine.

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 relation between the crankshaft and camshaft in a defined angular range, between a maximum early and a maximum late position variable. For this purpose, the device is integrated in a drive train via which torque from the crankshaft to the Camshaft is transmitted. This drive train can be realized for example as a belt, chain or gear drive.

Such a device is for example from the US Pat. No. 6,450,137 B2 or US 2003/0188704 A1 known. The device comprises two mutually rotatable rotors, wherein an outer rotor is in driving connection with the crankshaft and the inner rotor is rotatably connected to the camshaft. The device comprises four pressure chambers, wherein each of the pressure chambers is subdivided by means of a wing into two counteracting pressure chambers. By pressure medium supply to the pressure chambers or pressure fluid discharge from the chambers, the wings are moved within the pressure chambers, whereby a targeted rotation of the rotors to each other and thus the camshaft is caused to the crankshaft.

The pressure medium inflow to, or the pressure drain from the pressure chambers is controlled by means of a control unit, usually a hydraulic directional control valve (control valve). Starting from the control valve pressure medium lines are provided, which open into the respective pressure chambers.
The control unit, in turn, is controlled by means of a regulator which, with the aid of sensors, determines the actual and desired position of the phase angle of the camshaft in the internal combustion engine and compares them with one another. If a difference is detected between the two positions, a signal is sent to the control unit, which adjusts the pressure medium flows to the pressure chambers to this signal.

In order to ensure the function of the device, the pressure in the pressure medium circuit of the internal combustion engine must exceed a certain value. Since the pressure medium is usually provided by the oil pump of the internal combustion engine and the pressure provided thus increases synchronously with the speed of the internal combustion engine, below a certain speed of the oil pressure is still too low to change the phase position of the rotors targeted or keep. This may for example be the case during the starting phase or idling phases of the internal combustion engine.

During these phases, the device would make uncontrolled oscillations, resulting in increased noise emissions, increased wear, choppy running, and increased raw engine emissions. To prevent this, a locking mechanism is provided which couples the two rotors mechanically non-rotatably during the critical operating phases of the internal combustion engine.

The locking mechanism comprises two rotational angle limiting devices, wherein a first rotational angle limiting device in the locked state allows an adjustment of the inner rotor to the outer rotor in an interval between a maximum late position and a defined center position (locking position). The second rotation angle limiting device allows in the locked state, a rotation of the inner rotor to the outer rotor in an interval between the center position and the maximum early position. If both rotational angle limits are in the locked state, the phase angle of the inner rotor to the outer rotor is limited to the middle position.
Each of the rotation angle limiting devices consists of a spring-loaded pin, which is arranged in a bore of the outer rotor. Each of the pins is acted upon by a spring in the direction of the inner rotor with a force. On the inner rotor per pin a receptacle is formed, which faces the corresponding pin in certain operating positions of the devices. In these operating positions, the spring-loaded pins can engage in the receptacle. In this case, the respective rotation angle limiting device moves from the ent to the locked state.

Each of the rotation angle limiting devices can be transferred by pressurizing the recording from the locked to the unlocked state. In this case, the pressure medium urges the pin back into its receptacle, whereby the mechanical coupling of the inner rotor to the outer rotor is canceled. In order to ensure the supply of pressure medium, each of the rotation angle limiting devices is in communication with one of the pressure medium lines. These run from the control valve to the respectively receiving one of the rotation angle limiting devices and from there into the corresponding pressure chamber.

wobei h die axiale Länge der Druckkammer, R der Abstand zwischen der Drehachse des Nockenwellenverstellers und der Innenmantelfläche der Druckkammer und r der Abstand zwischen der Drehachse des Nockenwellenverstellers und der Außenmantelfläche des Innenrotors neben den Flügeln ist.During the starting process and the idling phases of the internal combustion engine, the two rotors are mechanically coupled by means of the rotation angle limiting devices. However, the inner rotor performs a small amplitude oscillatory motion relative to the outer rotor. The cause of these oscillations is the locking play of the rotation angle limiting devices, which is necessary to allow a secure locking of the pins in the receptacles, in conjunction with the alternating torque, which acts on the camshaft during operation of the internal combustion engine. Due to the alternating moments of the inner rotor is first rotated relative to the outer rotor in a circumferential direction until this rotation is stopped by a rotational angle limiting device (first end position). Subsequently, a rotation takes place in the opposite circumferential direction until this rotation is stopped by the other rotation angle limiting device (second end position). The phase difference between these end positions corresponds to an angle φ, which is defined by the locking play. During a movement from the first to the second end position, the volume of one of the two counteracting pressure chambers decreases by the amount V, while the volume of the other pressure chamber increases by the amount V. Where: $$V=\frac{\phi }{360°}\cdot \pi \cdot H\cdot \left(R^2-{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\right).$$

where h is the axial length of the pressure chamber, R is the distance between the axis of rotation of the camshaft adjuster and the inner lateral surface of the pressure chamber and r is the distance between the axis of rotation of the camshaft adjuster and the outer circumferential surface of the inner rotor adjacent to the vanes.

If the pressure chambers are empty or not completely filled with pressure medium during the idling phases or the starting phase, then the oscillation of the inner rotor relative to the outer rotor could cause a pumping effect. This pumping effect can promote pressure medium in one or more pressure chambers. Thereby For example, one or more pressure chambers can be completely filled with pressure medium without the pressure medium pump providing sufficient system pressure to operate the device functionally reliable, ie to keep phase positions securely or to adjust them in a targeted manner.

If the volume of a completely filled pressure chamber is reduced by the amount V due to the oscillations, pressure spikes in the pressure medium system are produced which are sufficient to displace one or both pins of the rotational angle limiting devices out of the receptacle into their bores. Thus, the mechanical coupling of the device is removed at a time when the system pressure is insufficient to fix or adjust the phase angle of the device (for example, in the start or idle phases). This leads to oscillations of large amplitude of the inner rotor relative to the outer rotor in the circumferential direction of the device, whereby the exhaust behavior of the internal combustion engine is adversely affected and in the worst case, their startability is not guaranteed.
Another device is from the US 6,684,835 B2 known. Deviation is provided here only one receptacle for the pins of both rotation angle limiting device. Furthermore, the recording is acted upon via a connecting line with pressure medium, which is formed separately from the pressure medium line, which connect the control valve with the pressure chambers. The connecting line communicates on the one hand with the receptacle, on the other hand with a connection of the control valve.

Also in this embodiment, pressure peaks are generated in the device, which can propagate through the control valve to the recording and lead to the same problems.

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 an unintentional unlocking a rotation angle limiting device during the idle periods and / or the start phase should be avoided.

The object is achieved in that a minimum response pressure of the rotational angle limiting device is greater than a minimum response pressure of the pressure accumulator.
In this case, the minimum response pressure is understood to be the system pressure at which a filling of the pressure accumulator begins, or the engagement element begins to lift off a stop of the receptacle.

The device is for example, as in the prior art, in the form of a Flügelradverstellers and has a drive element (outer rotor), which is driven for example by means of a Zugmittel- or gear drive from a crankshaft of the internal combustion engine. Furthermore, an output element (inner rotor) is provided, which has a constant phase position to a camshaft, for example, by means of a friction, schraub-, non-positive or cohesive connection rotatably connected thereto. Within the device a plurality of pressure chambers are formed, which are divided by a respective wing in two counteracting pressure chambers. The wings are connected to the output element or the drive element. The pressure chambers can be connected by means of a control valve with a pressure medium pump or a tank. By supplying pressure medium to or pressure fluid removal from the pressure chambers, the wings are moved within the pressure chambers, whereby the relative phase position of the output element to the drive element and thus the camshaft can be adjusted to the crankshaft changeable.
Alternatively, other embodiments of the device may be provided, for example devices in Axialverstellerbauweise, in which an axially displaceable by pressure medium piston cooperates by means of helical gears with the output element and the drive element.

The device has a locking mechanism which has a mechanical, for example positive, coupling of the output element to the drive element allows. In this case, the locking mechanism may consist of one or more rotational angle limiting devices. The rotational angle limiting devices can assume a locked state in which the possible phase positions of the output element to the drive element are limited to an angular interval that is smaller than the maximum permitted angular interval of the device. In this case, the rotation angle limiting device restrict the permitted phase range to a defined angular interval or a defined (gap-laden) angle. By pressurizing the rotational angle limiting devices, these can be converted into an unlocked state, in which the device has its entire angular interval available.
A conceivable embodiment of a rotation angle limiting device consists of an engagement element, for example a pin or a plate, and a receptacle for the engagement element. The receptacle can be designed, for example, as a long groove along a section of a circular line or a recess which is adapted to the engagement element. Also conceivable is an embodiment in the form of a stepped link, in which a recess adapted to the engagement element is additionally formed within a slot.

The recording of the rotation angle limiting device can be acted upon via a control line, for example with one of the pressure chambers or via the control valve and additional pressure medium lines with pressure medium.

In addition, an accumulator is provided, which communicates with the hydraulic fluid system, in particular with the recording of the rotational angle limiting device. This communication can be done directly or via the control line and / or a discharge line. The pressure accumulator may for example be arranged in the output element or the drive element and be connected via a discharge line with the receptacle or the control line permanently or only in certain phase positions of the output element relative to the drive element. The relief line may be formed, for example, as a recess on the output element or the drive element. Alternatively, the accumulator of the control line or the receptacle opposite, especially if the receptacle is formed as a long groove. Thus, the accumulator is permanently or in certain phases, directly connected to the control line or the recording.

If the pressure medium supply of the receptacle is not via one of the pressure chambers, but via a pressure medium line, which is connected, for example, with an additional control port which is formed on the control valve, the pressure accumulator can also be arranged outside the device, for example in a cylinder head or cylinder head cover. In this case, one or more pressure accumulators may be connected to one or more pressure medium lines connecting the control valve to the pressure chambers and / or the receptacle.

The pressure accumulator can be configured, for example, as a pressure spring accumulator, bladder accumulator or disc spring accumulator.

If the response pressure of the pressure accumulator is chosen to be smaller than the response pressure of the rotational angle limiting device, initially the accumulator is filled before the rotational angle limiting device is transferred to an unlocked state. Thus, the pressure spikes that occur when the inner rotor is mechanically coupled to the outer rotor are trapped by the pressure accumulator. Thus, the device initially remains in the locked state and the starting capability and the idling behavior of the internal combustion engine are not adversely affected.

Furthermore, it can be provided that the minimum response pressure of the rotational angle limiting device is greater than a minimum filling pressure at which the pressure accumulator is filled to the maximum. Thus, the unlocking of the rotation angle limiting device begins only when the accumulator is completely filled.

wobei ϕ der durch das Verriegelungsspiel der Drehwinkelbegrenzungsvorrichtungen maximal mögliche Verdrehwinkel zwischen Innenrotor und Außenrotor, h die axiale Länge der Druckkammer, R der Abstand zwischen der Drehachse des Innenrotors und der Innenmantelfläche der Druckkammer und r der Abstand zwischen der Drehachse des Innenrotors und dessen Außenmantelfläche ist.
Dies ist besonders dann vorteilhaft, wenn die Aufnahme direkt mit einer der Druckkammern kommuniziert. Dabei entspricht V dem Volumen, welches während einer Oszillation, die auftritt, wenn der Innenrotor mechanisch mit dem Außenrotor gekoppelt ist, maximal in Richtung der Aufnahme einer Drehwinkelbegrenzungsvorrichtung gefördert werden kann. Somit wird Druckmittel, das während der Oszillation in Richtung der Aufnahme gefördert wird, vollständig von dem Druckspeicher aufgenommen und eine Entriegelung der Drehwinkelbegrenzungsvorrichtung verhindert.In a further development of the invention it is provided that the output element is fixed relative to the drive element with locked rotation angle limiting device or locked Drehwinkelbegrenzungsvorrichtungen in an angular interval about a defined phase position, wherein the angular interval is defined by the locking clearance, wherein in this locked state of the device, the pressure chamber can assume maximum and a minimum volume and wherein the volume of the pressure accumulator corresponds to at least the volume difference between the maximum and the minimum volume. For an embodiment of the device in impeller construction, the following results: $$V\ge \frac{\phi }{360°}\cdot \pi \cdot H\cdot \left(R^2-{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="imgf0001.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\right).$$

where φ is the maximum possible angle of rotation between inner rotor and outer rotor by the locking clearance of the rotational angle limiting devices, h is the axial length of the pressure chamber, R is the distance between the axis of rotation of the inner rotor and the inner lateral surface of the pressure chamber and r is the distance between the axis of rotation of the inner rotor and its outer circumferential surface.
This is particularly advantageous if the recording communicates directly with one of the pressure chambers. In this case, V corresponds to the volume which, during an oscillation which occurs when the inner rotor is mechanically coupled to the outer rotor, can be conveyed maximally in the direction of receiving a rotational angle limiting device. Thus, pressure medium, which is conveyed during the oscillation in the direction of the recording, completely absorbed by the pressure accumulator and prevents unlocking of the rotation angle limiting device.

In a development of the invention, it is provided that the volume of the pressure accumulator corresponds at least to the volume which is conveyed into one of the pressure chambers during the starting phase.
If the inertia of the pressure accumulator exceeds a certain value, there is the possibility that during the expansion of that pressure chamber which is connected to the receptacle, pressure medium does not return from the pressure accumulator is conveyed into the pressure chamber, but remains in this. Due to the pumping effect pressure medium can be replenished via the control valve in the pressure chamber in this case. Thus, a defined amount of pressure medium is introduced into the pressure accumulator in each period of the oscillation of the inner rotor relative to the outer rotor. Corresponds to the volume that can accommodate the pressure accumulator, the volume that can be supplied during the start-up phase in this pressure chamber, so this is absorbed by the pressure accumulator. Consequently, the rotation angle limiting devices remain in the locked state. The volume which can be supplied to the pressure chamber at the maximum during the start phase corresponds to the volume V of equation (1) multiplied by the number of oscillations which are carried out until the start phase has ended, for example idling speed is reached.

In a further development of the invention, it is provided that the rotation angle limiting device has at least one receptacle and at least one engagement element subjected to force in the direction of the receptacle, wherein the pressure reservoir communicates with the receptacle via a relief line. In this case, the relief line may be formed, for example, as a groove in a side cover of the device, the inner rotor or a bore in the inner rotor.
It can be provided that the recording can be acted upon via a control line with pressure medium and the pressure accumulator communicates with a discharge line, which opens downstream of the control line into the receptacle.

Alternatively it can be provided that the accumulator communicates directly with the recording. Directly here is to be understood that pressure medium can be supplied from the rotational angle limiting device to the pressure accumulator without the interposition of further pressure medium paths. It can be provided that the movement of a movable element of the pressure accumulator, for example a pressure piston of a spring piston accumulator, is partially covered by an edge of the receptacle. Thus, can be prevented that this emerges from the accumulator in the recording.

Alternatively, the pressure accumulator can be arranged within the engagement element of the rotation angle limiting device. This can be achieved, for example, by providing the engagement element, for example a pin, with a bore. This bore communicates with the receptacle of the rotational angle limiting device, for example via an opening of the pin on the end facing the receptacle. Within the bore, for example, a pressure piston is arranged axially displaceable against the force of a spring. For example, the spring may be supported on a radially inwardly extending collar formed at the open end of the bore of the pin. Alternatively, radially inwardly extending tabs can be provided, which are folded after insertion of the spring into the bore in its radially extending end position.

Alternatively it can be provided that the pressure accumulator communicates directly or via a discharge line with the control line. In this case, the recording can be acted upon with pressure medium via the control line. The control line may for example be formed as a groove in a side cover of the device, the inner rotor or a bore in the inner rotor. Likewise, the relief line, for example, take one of these forms. In this case, the control line can communicate with one or more of the pressure chambers, for example. Alternatively, the control line can communicate with a pressure medium line, which is connected on the one hand to a connection of the control valve and on the other hand to one of the pressure chambers. It would also be conceivable that this pressure medium line is connected on the one hand to a connection of the control valve and communicates exclusively with the control line. Thus, the discharge line or the accumulator itself opens between the place of origin of the pressure peaks and the rotation angle limiting device in the control line, so that the pressure peaks first meet the accumulator before they act on the rotation angle limiting device.
In a further embodiment, a control valve and at least two pressure medium lines, which communicate with the control valve, are provided, wherein one of the pressure medium lines communicates with the pressure chamber and the other pressure medium line with the control line and wherein the pressure accumulator communicates directly or via a discharge line with one of these pressure medium lines.
It can be provided that the discharge line opens into the pressure medium line, which communicates with the pressure chamber or the control line. Thus, the arrangement of the pressure accumulator can be made flexible within the internal combustion engine and respond flexibly to space limitations

In an embodiment of the invention it can be provided that the pressure accumulator is arranged in the output element. Thus, no additional space is needed, but exploited the unused area of the inner rotor. Furthermore, the functional reliability is increased by the spatial proximity to the rotation angle limiting device.

The control line may be formed as a recess on the output element or the drive element. Likewise it can be provided that the control line on the one hand opens into the pressure chamber and on the other hand communicates with the rotation angle limiting device.

Brief description of the drawings

Figur 1

nur sehr schematisch eine Brennkraftmaschine,

Figur 2a

eine Draufsicht auf eine erste erfindungsgemäße Ausführungsform einer Vorrichtung zur Veränderung der Steuerzeiten von Gaswechselventilen einer Brennkraftmaschine incl. einem angeschlossenen Hydraulikkreislauf,

Figur 2b

einen Längsschnitt durch die Vorrichtung aus Figur 2a entlang der Linie IIB-IIB,

Figur 3

eine Draufsicht auf eine zweite erfindungsgemäße Ausführungsform einer Vorrichtung zur Veränderung der Steuerzeiten von Gaswechselventilen einer Brennkraftmaschine incl. einem angeschlossenen Hydraulikkreislauf,

Figur 4a

eine Draufsicht auf eine dritte erfindungsgemäße Ausführungsform einer Vorrichtung zur Veränderung der Steuerzeiten von Gaswechselventilen einer Brennkraftmaschine incl. einem angeschlossenen Hydraulikkreislauf,

Figur 4b

einen Längsschnitt durch die Vorrichtung aus Figur 4a entlang der Linie IVB-IVB,

Figur 5

eine Draufsicht auf eine vierte erfindungsgemäße Ausführungsform einer Vorrichtung zur Veränderung der Steuerzeiten von Gaswechselventilen einer Brennkraftmaschine.

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

FIG. 1

only very schematically an internal combustion engine,

FIG. 2a

a plan view of a first embodiment according to the invention of a device for changing the timing of Gas exchange valves of an internal combustion engine including a connected hydraulic circuit,

FIG. 2b

a longitudinal section through the device FIG. 2a along the line IIB-IIB,

FIG. 3

a plan view of a second embodiment of the invention an apparatus for changing the timing of gas exchange valves of an internal combustion engine incl. An attached hydraulic circuit,

FIG. 4a

a plan view of a third embodiment according to the invention of a device for changing the timing of gas exchange valves of an internal combustion engine including a connected hydraulic circuit,

FIG. 4b

a longitudinal section through the device FIG. 4a along the line IVB-IVB,

FIG. 5

a plan view of a fourth embodiment of the invention an apparatus for changing the timing of gas exchange valves of an internal combustion engine.

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 device 10 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 intake gas exchange valves 9a or one or more exhaust gas exchange valves 9b. Likewise, it can be provided to equip only one of the camshafts 6, 7 with a device 10, or to provide only a camshaft 6, 7, which is provided with a device 10.

The FIGS. 2a and 2 B show a first embodiment of a device 10 according to the invention in longitudinal section and in a lateral plan view.
The device 10 has a drive element designed as an outer rotor 22 and an output element designed as an inner rotor 23. The outer rotor 22 has a housing 22a and two side covers 24, 25 disposed on the axial side surfaces of the housing 22a. The inner rotor 23 is designed in the form of an impeller and has a substantially cylindrically designed hub member 26, extend from the outer cylindrical surface in the illustrated embodiment, five wings 27 in the radial direction outwards. In this case, the wings 27 may be integrally formed with the hub member 26. Alternatively, the wings 27, as in FIG. 2a shown separately formed and arranged in axially extending vane grooves 28 which are formed on the hub member 26. The wings 27 are acted upon by means of winged springs 27a, which are arranged between the Nutgründen the vane grooves 28 and the wings 27, radially outwardly with a force.

Starting from an outer peripheral wall 29 of the housing 22a, a plurality of projections 30 extend radially inwardly. In the illustrated embodiment, the projections 30 are formed integrally with the peripheral wall 29. However, embodiments are also conceivable in which, instead of the projections 30, additional wings are provided which are attached to the peripheral wall 29 and extend radially inwards. The outer rotor 22 is mounted by means of radially inner circumferential walls of the projections 30 relative to the inner rotor 23 rotatably mounted on this.

On an outer circumferential surface of the peripheral wall 29, a sprocket 21 is arranged, by means of which, via a chain drive, not shown, torque can be transmitted from the crankshaft 2 to the outer rotor 22.

The sprocket 21 may be formed as a separate component and rotatably connected to the outer rotor 23 or formed integrally therewith. Alternatively, a belt or gear drive can be provided.

Depending on one of the side covers 24, 25 is arranged on one of the axial side surfaces of the housing 22a and rotatably fixed thereto. In each of the projections 30, an axial opening is provided for this purpose, wherein each axial opening is penetrated by a fastening element 32, for example a bolt or a screw, which serves for the rotationally fixed fixing of the side covers 24, 25 on the housing 22a.

Within the device 10, a pressure space 33 is formed between each two circumferentially adjacent projections 30. Each of the pressure chambers 33 is circumferentially bounded by opposing, substantially radially extending boundary walls 34 of adjacent projections 30, in the axial direction of the side covers 24, 25, radially inwardly of the hub member 26 and radially outwardly of the peripheral wall 29. In each of the pressure chambers 33 projects a wing 27, wherein the wings 27 are formed such that they rest against both the side covers 24, 25, and on the peripheral wall 29. Each wing 27 thus divides the respective pressure chamber 33 into two oppositely acting pressure chambers 35, 36.

The inner rotor 23 is rotatable in a defined Winkelbreich to the outer rotor 22. The angular range is limited in a rotational direction of the inner rotor 23 in that each wing 27 comes to rest on one of the boundary walls 34 (early stop 34a) of the pressure chambers 33. Similarly, the angular range in the other direction of rotation is limited by the fact that the wings 27 come to rest on the other boundary walls 34 of the pressure chambers 33, which serve as a late stop 34b. The angle range thus defined represents the maximum possible angular range within which the phase angle between the outer rotor 22 and the inner rotor 23 can be varied. Likewise conceivable are embodiments in which only one or some of the wings 27 come into contact with the end stops 34a, b. alternative a rotation limiting device may be provided which limits the maximum possible rotation angle range of the inner rotor 23 to the outer rotor 22.

By pressurizing a group of pressure chambers 35, 36 and pressure relief of the other group, the phase angle of the outer rotor 22 to the inner rotor 23 can be varied. By pressurizing both groups of pressure chambers 35, 36, the phase position of the two rotors 22, 23 are kept constant to each other. Alternatively it can be provided to pressurize none of the pressure chambers 35, 36 during phases of constant phase position with pressure medium. As hydraulic pressure medium usually the lubricating oil of the internal combustion engine 1 is used.

For the supply of pressure medium to or pressure medium removal from the pressure chambers 35, 36, a pressure medium system is provided, which comprises a pressure medium pump, not shown, a likewise not shown tank, a control valve 37 and a plurality of pressure medium lines 38a, b, p, s. The control valve 37 has a pressure medium connection P, a tank connection T, two working connections A, B and a control connection S. The first pressure medium line 38a connects the first working port A to the first pressure chambers 35. The second pressure medium line 38b connects the second working port B to the second pressure chambers 36. The third pressure medium line 38p connects the pressure medium pump to the pressure medium port P. In the case of a control valve 37, which in the axial opening 31 of the device 10 is arranged, the pressure medium lines 38a, b, s in the inner rotor 23 extend. These may be formed, for example, as bores or radially extending grooves in the axial side surfaces. In the case of control valves 37 which are accommodated in a receptacle outside the device 10, for example a cylinder head, the pressure medium line 38a, b, s include additional hydraulic fluid paths which connect the control valve 37 with the bores or grooves formed on the inner rotor 23.

Pressure medium conveyed by the pressure medium pump is supplied to the control valve 37 via the third pressure medium line 38p. Depending on the control state of the Control valve 37, the third pressure medium line 38p connected to the first pressure medium line 38a, the second pressure medium line 38b or with both or none of the pressure medium lines 38a, 38b.

In order to shift the control times (opening and closing times) of the gas exchange valves 9a, 9b in the direction early, the pressure medium supplied to the control valve 37 via the third pressure medium line 38p is conducted via the first pressure medium line 38a to the first pressure chambers 35. At the same time, pressure medium from the second pressure chambers 36 reaches the control valve 37 via the second pressure medium line 38b and is ejected into the tank. As a result, the wings 27 are displaced in the direction of the early stop 34a, whereby a rotary movement of the inner rotor 23 to the outer rotor 22 in the direction of rotation of the device 10 is achieved.
In order to shift the timing of the gas exchange valves 9a, 9b in the direction of late, the pressure medium supplied to the control valve 37 via the third pressure medium line 38p is conducted via the second pressure medium line 38b to the second pressure chambers 36. At the same time, pressure fluid from the first pressure chambers 35 reaches the control valve 37 via the first pressure medium line 38a and is ejected into the tank. As a result, the wings 27 are displaced in the direction of the late stop 34b, whereby a rotational movement of the inner rotor 23 to the outer rotor 22 opposite to the direction of rotation of the device 10 is achieved.
In order to keep the control times constant, the pressure medium supply to all pressure chambers 35, 36 is either prevented or permitted. As a result, the wings 27 are hydraulically clamped within the respective pressure chambers 33, and thus prevents a rotational movement of the inner rotor 23 to the outer rotor 22.

During the start of the internal combustion engine 1, the system pressure increases with the rotational speed of the crankshaft 2. Thus, initially there is not enough system pressure to ensure the hydraulic clamping of the vanes 27 within the pressure chambers 33. In order to prevent uncontrolled swinging of the inner rotor 23 to the outer rotor 22 is a locking mechanism 41st provided, which establishes a mechanical connection between the two rotors 22, 23. In some applications, the system pressure is too low even during idle periods to ensure safe operation of the device. In these cases, the mechanical coupling is also provided during the idling phases.

In the in the FIGS. 2a . 2 B illustrated embodiment of the device 10, the locking position is selected such that the wings 27 are in the locked state of the device 10 in a position between the early stop 34a and the late stop 34b.

The locking mechanism 41 consists in this embodiment of a first and a second rotational angle limiting device 42, 43. In the illustrated embodiment, each of the rotational angle limiting devices 42, 43 comprises an axially displaceable engagement element, which is formed in the specific embodiment as a pin 44. Each of the pins 44 is received in a bore of the inner rotor 23. In addition to pins 44, other engagement elements can be used, such as plates.
Furthermore, two receptacles 45 in the form of circumferentially extending grooves are formed in the first side cover 24. These are in FIG. 2a indicated in the form of broken lines. Each of the pins 44 is acted upon by means of a spring element 46 with a force in the direction of the first side cover 24. If the inner rotor 23 to the outer rotor 22 a position in which a pin 44 in the axial direction of the associated receptacle 45 facing, so this is urged into the receptacle 45 and the respective rotation angle limiting device 42, 43 transferred from an unlocked to a locked state. In this case, the receptacle 45 of the first rotational angle limiting device 42 is designed such that the phase position of the inner rotor 23 is limited to the outer rotor 22, with locked first rotational angle limiting device 42 to a range between a maximum early and the locking position. When the inner rotor 23 is in the locking position relative to the outer rotor 22, the pin 44 of the first rotational angle limiting device 42 is located at a circumferential direction formed by the receptacle 45 stop, thereby preventing further adjustment in the direction of later control times.
Similarly, the receptacle 45 of the second rotation angle limiting device 43 is designed such that, when the second rotation angle limiting device 43 is locked, the phase angle of the inner rotor 23 to the outer rotor 22 is limited to a region between a maximum retarded position and the locking position.

In order to transfer the rotational angle limiting devices 42, 43 from the locked to the unlocked state, it is provided that pressure is applied to the respective receptacle 45. As a result, the respective pin 44 is pushed back against the force of the spring element 46 into the bore and thus eliminates the rotation angle limitation.
In the illustrated embodiment, it is provided to supply the receptacle 45 of the first rotation angle limiting device 42 from one of the second pressure chambers 36 via a control line 48 with pressure medium. The control line 48 extends between the second pressure chamber 36 and the receptacle 45.
For pressurizing the receptacle 45 of the second rotation angle limiting device 43, a control line 48 is also provided. This communicates on the one hand with the receptacle 45 and on the other hand with a channel 49 which is formed within the inner rotor 23. The channel 49 communicates with the fourth pressure medium line 38s, which is connected to the control terminal S.
The control lines 48 are formed as grooves in the first side cover 24. Alternatively, they may also be formed in the side surface of the inner rotor 23.

The different embodiments of pressurizing the various rotational angle limiting devices 42, 43 are chosen for illustrative purposes only to illustrate various embodiments of the invention. Of course, both Drehwinkeibegrenzungsvorrichtungen 42, 43 are acted upon by the pressure chambers 35, 36 or the control valve 37 with pressure medium.

During the starting phase, the hydraulic clamping of the wings 27 within the pressure chambers 33 due to low system pressure is generally not guaranteed. For this reason, the inner rotor 23 performs oscillatory movements with respect to the outer rotor 22 in the circumferential direction. These oscillations are caused by the alternating torques acting on the camshaft 6, 7, the oscillations occurring even in the locked state of the device 10. Their angle amplitude φ is determined by the locking game. The oscillations result in a pumping action whereby residual oil present in the pressure medium lines 38a, b can be conveyed into the pressure chambers 35, 36. This is especially true when the pressure chambers 35, 36 are not connected to the tank port T, but, for example, with the pressure medium line 38p. Negative effects can also occur if one of the working ports A, B is closed. In this case, pressure medium, due to leakage within the control valve 37 to the pressure chambers 35, 36 are promoted. If in this way the second pressure chamber 36, which is connected to the receptacle 45 of the first rotation angle limiting device 42, completely filled with pressure medium, the pressure peaks generated in the pressure chamber 35 propagate to the pin 44 of the first rotation angle limiting device 42. This can lead to an undesired, premature unlocking of the first rotation angle limiting device 42, at a point in time in which the system pressure is still too low to ensure hydraulic clamping of the vanes 27. This effect can also occur during the idling phases of the internal combustion engine 1.
Analogously, the pressure peaks can even propagate via the first or second pressure medium line 38a, b, the control valve 37, the fourth pressure medium line 38s, the channel 49 and the control line 48 to the receptacle 45 of the second rotation angle limiting device 43 and also convert this prematurely in the unlocked state , As a consequence, eliminates the mechanical coupling between the inner rotor 23 and the outer rotor 22, whereby the Device 10 performs uncontrolled high amplitude oscillations until the system oil pressure has reached a level sufficient to control device 10.

To counteract this process, two pressure accumulators 50a, b are provided. Both accumulators 50a, b are integrated in the illustrated embodiment in the inner rotor 23. It may, for example, as in FIG. 2b shown to act a compression spring memory. This pressure accumulator 50a, b has a pressure piston 51, which is arranged within a bore of the inner rotor 23 and is urged by a spring 52 against the first side cover 24. In contrast to the rotational angle limiting device 42, 43, the pressure piston 51 does not produce a positive connection between the inner rotor 23 and the outer rotor 22, but provides only an additional volume for the pressure medium. The pressure piston 51 abuts on the first side cover 24 in the illustrated embodiment when the pressure accumulator 50a is completely emptied. This has the advantage that during the first revolutions of the camshaft 6, 7 due to the oscillations of the inner rotor 23 relative to the outer rotor 22 acts on the pressure piston 51, a force that loosens this, if this example, due to residual pressure on the wall of the bore sticks. Alternatively, a stop can be provided within the bore, which prevents the pressure piston 51 comes to rest on the first side cover 24. Alternatively, other types of pressure accumulators, for example bladder accumulator or disc spring accumulator, can be used.

The first pressure accumulator 50 a communicates via a first relief line 54 with the receptacle 45 of the first rotation angle limiting device 42. The relief line 54 is formed as a groove in the first side cover 24 and designed such that it communicates with the first pressure accumulator 50 a, as long as the inner rotor 23 a relative Phase position to the outer rotor 22 assumes that lies between the locking position and the maximum early position. For this purpose, this extends along a circular line, the first pressure accumulator 50a departs during an adjustment from the maximum early position to the locking position.

The second pressure accumulator 50b communicates via a second relief line 54 with the channel 49. The relief line 54 is formed in this case as a groove in the side surface of the inner rotor 23 and extends from the channel 49 to the second pressure accumulator 50b. Thus, the second pressure accumulator 50b communicates in each position of the inner rotor 23 to the outer rotor 22 with the channel 49. In contrast to the first pressure accumulator 50a, a front-side recess 53 of the pressure piston 51 of the second pressure accumulator 50b is provided. This is designed as a radially outer annular surface. Thus, the pressure medium, which is supplied to the second pressure accumulator 50b, enough effective area available to move the plunger 51 against the force of the spring 52, even if it rests against the first side cover 24.

Pressure peaks generated in the pressure chambers 35, 36 are applied both to the pressure piston 51 and to the pins 44. If the pressure of the pressure peaks exceeds a certain first pressure (first response pressure), the pressure pistons 51 are moved counter to the force of the spring 52, thereby providing an additional volume for the pressure medium.
If the pressure of the pressure peaks exceeds a certain second pressure (second response pressure), the pins 44 of the rotational angle limiting devices 42, 43 are moved against the force of the spring elements 46, whereby the mechanical coupling of the inner rotor 23 to the outer rotor 22 is canceled. The pressure accumulators 50a, b and the rotational angle limiting devices 42, 43 are designed such that the second response pressure is higher than the first response pressure. This can be done for example by suitable design of the springs 52 and spring elements 46, taking into account the surfaces on which the pressure medium acts. Thus, first, a filling of the pressure accumulator 50a, b, before the pin 44 of the corresponding rotation angle limiting device 42,43 is pushed back into the bore.

In addition, the second response pressure may be selected to be greater than the pressure that is at least necessary to completely fill the corresponding pressure accumulator 50a, b (minimum inflation pressure). Thus, an unlocking takes place only when the corresponding pressure accumulator 50a, b is completely filled.
Thus, during the starting phase and the idling phases of the engine 1, it can be prevented that the rotational angle limiting devices 42, 43 are unintentionally transferred to the unlocked state. Instead of the pins 44, the pressure pistons 51 are displaced under the action of the pressure peaks. The pressure accumulators 50a, b relax during the operating phases which follow the pressure peaks, ie the pressure pistons 51 move back in the direction of their rest positions in which the pressure accumulators 50a, b are emptied. In internal combustion engines 1, in which the dynamics of the pressure piston 51 is insufficient to return between two pressure peaks in their rest position, the pressure accumulators 50a, b act, especially during the start phases. Although the pressure accumulator 50a, b fill with each pressure peak, but unlocking of the rotational angle limiting devices 42, 43 is prevented until complete filling of the pressure accumulator 50a, b. If the volume of the pressure accumulator 50a, b is designed such that it corresponds at least to the volume which is conveyed into one of the pressure chambers 33 during the staring process up to the point in time at which sufficient system pressure is built up, an unwanted unlocking during the starting process can take place reliably avoided.
Furthermore, the time in which the device 10 can be operated at idle, without an unwanted unlocking of a rotational angle limiting device 42, 43 occurs extended.

In FIG. 3 a second embodiment of a device 10 is shown. This embodiment is substantially identical to the first embodiment. In contrast to the first embodiment, the receptacles 45 of both rotational angle limiting devices 42, 43 communicate via a respective control line 48 with the third pressure medium line 38s, which is connected to the control port S of the control valve 37. The control valve 37 regulates in In this embodiment, therefore, there is no direct connection between the pressure chambers 35, 36 and the receptacles 45 of the rotational angle limiting devices 42, 43. Pressure peaks can thus occur only propagate along the pressure medium line 38a, b via the control valve 37, the third pressure medium line 38s, the channels 49 and the control lines 48 to the receptacles 45.
The pressure accumulators 50a, b are not integrated in the inner rotor 23 in this embodiment. In a first embodiment, a pressure accumulator 50a communicates permanently with the control line 48. The pressure accumulator 50a is thus arranged between the point of origin of the pressure peaks, the pressure chambers 35, 36, and the receptacles 45.
Alternatively or additionally, pressure accumulator 50b may be provided, which communicate with the pressure medium lines 38a, b. In embodiments in which one of the two pressure medium lines 38a, b communicates with the tank during the critical start or idle phase, it is possible to dispense with the pressure reservoir 50b which communicates with this pressure medium line 38a, b, since any resulting pressure peaks are diverted to the tank and thus can not reproduce in the pressure medium system. The one or more pressure accumulator 50b communicate temporarily via the first and second pressure medium line 38a, b, the control valve 37, the third pressure medium line 38s, the channels 49 and the control lines 48 with the receptacles 45. This is always the case when both the third Pressure medium line 38s and one of the pressure chambers 35, 36 connected to the pressure medium line 38a, b are not connected to the tank.
The pressure accumulators 50a, b are designed to be identical to those described in the first embodiment.

The FIGS. 4a and 4b show a further embodiment of the invention. The pressure accumulator 50b is disposed within the pin 44 of the second rotational angle limiting device 43 in this embodiment. The pressure accumulator 50b consists of a pressure piston 51 which is arranged inside the hollow pin 44. The pressure piston 51 can against the Force of a spring 52 are displaced within the pin 44 in the axial direction. The spring 52 is supported on tabs 47, which are integrally formed with the pin 44 and, for example, after inserting the pressure piston 51 and the spring 52 are folded into the bore of the pin 44 in the radial direction. Alternatively, an annular circumferential collar can serve to support the spring 52.
The pressure medium loading of the pressure piston 51 from the receptacle 45 can be effected by means of an opening 40 which is formed in the front-side side surface of the pin 44, which points in the direction of the receptacle 45.

The pressure accumulator 50a is arranged in this embodiment such that it communicates directly with the receptacle 45 of the first rotation angle limiting device 42. In the illustrated case of a spring piston accumulator, this opens directly into the receptacle 45. In this case, the pressure accumulator 50a is arranged offset in the radial direction to the pin 44, so that the pressure piston 51 is partially covered by an edge of the receptacle 45. This ensures that the pressure piston 51 can be acted upon by the receptacle 45 with pressure medium, but 45 does not engage in this unpressurized recording. Alternatively, the pressure accumulator 50a may also have stops for the pressure piston 51 in order to retain it. In this embodiment, the pressure accumulator 50a can be arbitrarily arranged as long as it communicates with the receptacle 45.

FIG. 5 shows a further embodiment of a device 10. In contrast to the first two embodiments only one rotation angle limiting device 42 is provided here, which can couple the inner rotor 23 in a defined phase position (plus locking clearance) with the outer rotor 22. For this purpose, the receptacle 45 is not formed here as a groove in the circumferential direction, but as a recess which is adapted to the pin 44. Preferred locking phase positions are in the maximum early or maximum retarded position of the inner rotor 23 to the outer rotor 22. However, also middle positions are conceivable.

In the illustrated embodiment, the accumulator 50a and receptacle 45 communicate with one of the pressure chambers 35, 36 via the control line 48 and relief line 54 formed on the inner rotor 23 (solid lines). Alternatively, the lines may also be in the first side cover 24 be formed (dashed lines).

reference numeral

1

Internal combustion engine

2

crankshaft

3

piston

4

cylinder

5

traction drive

6

intake camshaft

7

exhaust

8th

cam

9a

Inlet gas exchange valve

9b

Auslassgaswechselventil

10

contraption

21

Sprocket

22

outer rotor

22a

casing

23

inner rotor

24

side cover

25

side cover

26

hub element

27

wing

27a

wing feather

28

vane

29

peripheral wall

30

head Start

31

axial opening

32

fastener

33

pressure chamber

34

boundary wall

34a

early stop

34b

late stop

35

first pressure chamber

36

second pressure chamber

37

control valve

38a

first pressure medium line

38b

second pressure medium line

38p

third pressure medium line

38s

fourth pressure medium line

40

opening

41

locking mechanism

42

Rotational angle limiting device

43

Rotational angle limiting device

44

pen

45

admission

46

spring element

47

flap

48

control line

49

channel

50a

accumulator

50b

accumulator

51

pressure piston

52

feather

53

deepening

54

relief line

A

first work connection

B

second work connection

P

inflow connection

T

drain connection

S

control connection

Claims (10)

1. Device (10) for variably adjusting the control times of gas exchange valves (9a, b) of an internal combustion engine (1), with

   - a driving element (22), an output element (23), at least one pressure chamber (35, 36), at least one mechanism (42, 43) limiting the angle of rotation, and at least one pressure accumulator (50a, b),

   - wherein a phase angle between the output element (23) and the driving element (22) can be changed within a maximum possible angular spread by delivering or discharging pressure medium to or from the pressure chamber (35, 36),

   - wherein each mechanism (42, 43) limiting the angle of rotation, in a locked state, limits the phase angle at least to an angular spread which is less than the maximum possible angular spread,

   - wherein the mechanism (42, 43) limiting the angle of rotation can be transferred into an unlocked state through the application of pressure medium via a control line (48), and

   - whereby the pressure accumulator (50a,b) communicates at least temporarily with the control line (48) during the operation of the internal combustion engine (1), characterized in that

   - a minimum response pressure of the mechanism (42, 43) limiting the angle of rotation is greater than a minimum response pressure for filling the pressure accumulator (50a,b).
2. Device (10) according to Claim 1, characterized in that the mechanism (42, 43) limiting the angle of rotation has at least one receiving member (45) and at least one engaging element (44) to which force is applied in the direction of the receiving member (45), whereby the pressure accumulator (50a,b) communicates directly or via a relief line (54) with the receiving member (45).
3. Device (10) according to Claim 1, characterized in that the pressure accumulator (50a,b) communicates directly or via a relief line (54) with the control line (48).
4. Device (10) according to Claim 1, characterized in that a control valve (37) and at least two pressure medium lines (38a,b,s) which communicate with the control valve (37) are provided, whereby one of the pressure medium lines (38a,b) communicates with the pressure chamber (35, 36) and the other pressure medium line (38s) communicates with the control line (48), and whereby the pressure accumulator (50a,b) communicates directly or via a relief line (54) with one of these pressure medium lines (38a,b,s).
5. Device (10) according to Claim 1, characterized in that the minimum response pressure of the mechanism (42, 43) limiting the angle of rotation is greater than a minimum filling pressure at which the pressure accumulator (50a, b) is filled to the maximum level.
6. Device (10) according to Claim 1, characterized in that the pressure accumulator (50a,b) is disposed in the output element (23).
7. Device (10) according to Claim 1, characterized in that the control line (48) is designed as a recess on the output element (23) or the driving element (22).
8. Device (10) according to Claim 1, characterized in that the control line (48) on the one hand opens out into the pressure chamber (35, 36) and, on the other hand, communicates with the mechanism (42, 43) limiting the angle of rotation.
9. Device (10) according to Claim 1, characterized in that the output element (23) is fixed relative to the driving element (22), when the mechanism(s) (42, 43) limiting the angle of rotation is/are locked, at an angular interval through a defined phase angle, whereby the angular interval is defined by the locking clearance, whereby, in this locked state of the device (10), the pressure chamber can assume a maximum and a minimum volume and whereby the volume of the pressure accumulator (50a,b) corresponds at least to the volume difference between the maximum and the minimum volume.
10. Device (10) according to Claim 1, characterized in that the mechanism (42, 43) limiting the angle of rotation has at least one receiving member (45) and at least one engaging element (44) to which force is applied in the direction of the receiving member (45), whereby the pressure accumulator (50a,b) is disposed within the engaging element (44).

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