DE102004048070B4 - Method for operating a hydraulically operated device - Google Patents

Abstract

Method for operating a hydraulically operated camshaft adjusting device (1) or a hydraulically operated device for changing the timing of gas exchange valves of an internal combustion engine of a vehicle, wherein the internal combustion engine is controlled by vehicle electronics (2) and wherein the device comprises at least one electrically controlled hydraulic valve (3) for influencing the flow of hydraulic oil through the device (1), characterized in that the at least one valve (3) at start of the internal combustion engine before reaching the idle speed with a predetermined current (IA) acted upon is, wherein an oil pressure of the hydraulic oil is below the operating oil pressure that the camshaft adjusting device (1) needs to operate.

Description

Field of the invention

The invention relates to a method for operating a hydraulically actuated camshaft adjusting device or a hydraulically operated device for changing the timing of gas exchange valves of an internal combustion engine of a vehicle, wherein the internal combustion engine is controlled by a vehicle electrical system or electronics and wherein the device at least one electrically controlled Hydraulic valve for influencing the flow of hydraulic oil through the device.

Camshaft adjusting devices of this type are well known in the art, with the example of the DE 103 44 816 A1 is pointed out. In the device, an impeller is present in which wings are molded or arranged. The wings are located in hydraulic chambers, which are incorporated in an outer rotor. By appropriate action on the respective side of the hydraulic chambers with hydraulic fluid, an adjustment of the inner rotor relative to the outer rotor between an "early stop" and a "late stop" can take place. The flow of hydraulic oil is controlled by an electrically controlled directional control valve.

The valve has a housing into which a valve bore is introduced. A control piston can move in a direction of displacement relative to the housing, for which purpose an electromagnetically actuated linear displacement element is used.

During operation of the internal combustion engine, the linear displacement element of the valve is acted upon by the vehicle electrics or electronics with such a control current that - depending on the engine parameters - a desired camshaft adjustment or adjustment of the gas exchange valves is accomplished.

The commonly used hydraulic valves cause problems at very low temperatures. At low temperatures, the viscosity of the working medium is relatively high. The armature in the actuating magnet of the solenoid-operated linear displacement element of the valve can stick firmly at these environmental conditions by adhesion forces. The ability to move and the achievable speed of movement of the valve, which is lubricated by the still tough working fluid, are thereby very limited. The first movements of the valve after the start of the internal combustion engine are therefore delayed in a disadvantageous manner or they have a disturbing dead time. This leads to a deteriorated operation of the internal combustion engine, since the function of the camshaft adjusting device or the device for changing the valve timing is impaired.

The problems of low temperatures when starting internal combustion engines are known in the art. In the DE 101 27 168 A1 a valve adjustment adjusting device is described which variably controls the timing of opening or closing of either an intake valve or an exhaust valve. In order to be able to operate the internal combustion engine stable even when cold, when it has just begun to run, a locking element is provided in the adjusting device.

In the DE 101 45 160 A1 For accelerating the activation of a catalytic converter in an internal combustion engine in the cold operating mode for a valve timing control system, it is provided that the control accuracy is increased by learning a reference position of a cam angle.

Another system for controlling a valve mechanism of an internal combustion engine is known from DE 43 17 748 A1 known. There, a detector is provided to detect a cold engine condition. In the given case, a cold engine signal is generated, due to which the valve setting becomes effective to advance the opening timing of the exhaust valve and to reduce the opening angle of the intake valve.

The DE 199 29 394 A1 discloses a driving strategy for the actuator of a camshaft adjusting device, which is intended to prevent jamming of the locking device. Such jamming can be caused by the high, one-sided acting on a chamber oil pressure.

The DE 196 04 865 A1 discloses an auxiliary oil supply which is intended to ensure hydraulic clamping of the camshaft adjusting device before starting the engine in order to prevent oscillation of the camshaft adjusting device. For this purpose, an operating oil pressure is generated by a second oil pump before the actual engine start and thus supplies the camshaft adjusting device.

However, all the previously known measures are not suitable to remedy the above problems, which are caused by the temperature-induced inertia of the actuating magnets of the hydraulic valves.

The present invention is therefore based on the object to propose a method of the type mentioned, with or with which the existing disadvantages can be solved. It Thus, it should be possible to reach an operating state of the machine as quickly as possible, even at low temperatures at the start of the internal combustion engine, in which a precise actuation of the camshaft adjusting device or the device for changing the timing of the gas exchange valves is possible. The response of the hydraulic valves used is to be improved.

The solution of this problem by the invention according to the method is characterized in that the at least one electrically actuated hydraulic valve is acted upon start or during starting of the internal combustion engine before reaching the idle speed with a predetermined current, wherein an oil pressure of the hydraulic oil is below the operating oil pressure that the camshaft adjusting device ( 1 ) needs to operate. Preferably, the valve from the time of switching on the vehicle electrics or electronics, ie from the "ignition", or immediately after this time applied to the predetermined current.

The valve current can be constant over time.

It can also be variable over time. It is considered as a preferred possibility that the time course of the predetermined current corresponds to that in later operation during the adjustment of the camshaft or when changing the timing of the gas exchange valves. It is also possible that the time course of the predetermined current corresponds to that of a PWM signal (pulse width modulation); This time course, a time-variable current can be superimposed with a second frequency.

The loading of the valve with the predetermined current can be terminated as soon as the internal combustion engine has reached a predetermined speed, in which case the valve is acted upon from this point on the operating current during the adjustment of the camshaft or when changing the timing of the gas exchange valves.

Alternatively or additionally, it can be provided that the admission of the valve with the predetermined current is terminated as soon as a predetermined time has elapsed, and that the valve is acted upon by the operating current from this point in time.

Finally, another possibility is that the admission of the valve with the predetermined current is terminated as soon as a predetermined oil pressure is reached in the internal combustion engine; also then shoots again to the admission of the operating current.

A further improvement in the warming of the valve and thus the production of a good performance can be achieved if further training, but also isolated considered, the valve at least in predetermined periods whenever an end position of the camshaft adjusting device or the device for changing the timing of the Gas exchange valves is reached, with a predetermined additional current is applied. The additional flow heats the valve without - due to the reached end position - producing a mechanical effect. The predetermined additional current can consist of short current pulses. The current pulses of the predetermined additional flow are therefore preferably chosen so that the camshaft adjusting device or the device for changing the timing of the gas exchange valves causes no adjustment.

The hydraulically actuated camshaft adjusting device associated with the method according to the invention or the hydraulically operated device for varying the valve timing is characterized in that it comprises means for applying a predetermined current at the start of the internal combustion engine to at least one electrically controlled hydraulic valve before the idling speed is reached comprising the flow of hydraulic oil through the device.

The proposed invention ensures that the hydraulic valve is already actuated for the first time when the engine is not yet started or while it is in the start-up and the subsequent speed-up phase.

The first movements of the armature in the actuating magnet of the solenoid-operated linear displacement element of the valve are already caused before it comes to a precise actuation of the armature for the control of the camshaft adjusting device or the device for varying the valve timing. This movement generates a breakaway effect of the component still in the viscous working medium, so that the particularly long dead time in the valve mechanism is present at a time when no oil pressure is built up in any case due to the not yet completely filled oil system by the engine oil pump is that the camshaft adjuster or the valve adjuster needs to operate. The Vorab actuation of the valve therefore has no adverse effect on the running of the internal combustion engine.

Furthermore, it is advantageously carried out by the early energization of the valve Vorab-heating of the magnetic part of the valve. As a result of this heating, the working medium (oil) lubricating the armature is also heated, as a result of which its viscosity decreases. As a result, it is less tough, which makes the anchor easier and faster to move.

Brief description of the drawings

In the drawing, an embodiment of the invention is shown. Show it:

1 a device shown only very schematically for the camshaft adjustment of an internal combustion engine including control electrics or electronics and

2 schematically the course of the flow in the directional control valve (solid curve) and the course of the engine speed (dashed curve) over time.

Detailed description of the drawings

In 1 is very schematically a phaser 1 to see an inner rotor 5 and an outer rotor 6 has, which can be adjusted relative to each other by means of the schematically outlined hydraulic adjustment mechanism to each other between two end position. The adjusting mechanism has, inter alia, at least one electrically controlled, hydraulic directional control valve 3 , a high pressure pump 7 and corresponding hydraulic lines 8th . 9 , To the functioning of the camshaft adjuster is on the DE 101 35 146 A1 pointed out, where the usual mode of action is explained.

The measures provided for the control or regulation of the internal combustion engine vehicle electrics or electronics is with 2 designated. The engine speed n at which the crankshaft of the engine rotates is determined by a speed sensor 10 determined and the vehicle electrical system or electronics 2 fed.

So that optimum operation is achieved as quickly as possible in the cold state of the internal combustion engine, the following procedure is provided:
In 2 the course of the engine speed n is shown over the time t. Until time t _I is the vehicle electrics and electronics 2 completely switched off. At t _I it is turned on, ie the "ignition" is turned on. As 2 can be seen, is up to the time t _I and no energization of the hydraulic valve 3 before (because the "ignition" is off). From t _I is the valve 3 However, applied to a predetermined current I _A , which has a constant value in the embodiment. So even though the engine is not turning yet, the valve is turning 3 already energized, whereby the armature, not shown, of the electromagnetically actuated linear displacement element of the valve 3 moved and so a detachment from the adhesion is accomplished, which causes the still highly viscous working medium (oil). Furthermore, the oil surrounding the armature by the energization of the valve 3 heat. The viscosity of the oil is thereby lowered, so that within a short time a precise operation of the camshaft adjuster can be achieved.

The energization of the valve 3 is indicated by means only schematically indicated 4 for applying the predetermined current I _A causes the part of the vehicle electrical system or electronics 2 are.

At time t _C of starting the engine is still the constant current I _A at the valve 3 at. The engine speed n gradually increases from this point in time to reach the operating idling speed at time t _B ; this corresponds to a predetermined speed n ₀ . The actual speed is determined by the speed sensor 10 registered and to the vehicle electrics or electronics 2 forwarded. This detects at the time t _B that the intended speed is present and causes the funds 4 for applying the current to the valve 3 from now on the operating current I _B abandon, ie the time variables and in 2 indicated current, the operation of the camshaft adjuster 1 is required (it should be noted that the current waveform shown is only to be understood schematically).

Preferably, the admission of the valve takes place 3 with the current I _A - like out 2 apparent - between the times t _I and t _B , ie in the period between "ignition on" and reaching the idle speed n ₀ , in any case before reaching the idle speed. It can further be provided that with the passage of a predetermined time, the switching from predetermined current I _A to operating current I _B takes place. Finally, the changeover from one to the other can also take place as a function of the achievement of a predetermined oil pressure in the engine.

In 2 is a constant given current I _A sketched. It can also be provided that this current acting to time t _B, is time-variable, different ways may be provided. For example, the operating current I _B can already be applied from the time t _I.

A special, in 2 However, not shown procedure is that the valve 3 whenever an end position of the camshaft adjusting device 1 is reached, with a defined additional current I _{Z is} applied. This additional current may consist of short pulses of current, which are selected by the frequency and the amplitude forth so that the camshaft adjusting device or the device for changing the valve timing causes no adjustment. Accordingly, the valve is energized whenever the controlled end stop of the camshaft adjuster or the device for changing the valve timing is energized with the short current pulses, so that the device does not react mechanically, but the energy input is higher than in normal operation in the controlled end position would be the case. Even so, the desired additional heating can be achieved.

• 1. Die Zündung wird eingeschaltet,
• 2. gleichzeitig beginnt die Beauschlagung mit vorgegebenem Strom I_A;
• 3. Der Anlasser wird betätigt und
• 4. der Motor wird gestartet (cranking);
• 5 Es erfolgt der Drehzahlhochlauf des Motors;
• 6. Nach Erreichen einer vorgegebenen Drehzahl und/oder einer vorgegebenen Zeit und/oder eines vorgegebenen Öldruckschwellwerts wird der vorgegebene Strom I_A abgeschaltet;
• 7. Der Motor wird in normalem Betrieb mit Nockenwellenversteller und/oder Vorrichtung zum Verändern der Steuerzeiten betrieben, d. h. der übliche Betriebsstrom I_B wird dem Ventil aufgegeben.

A first example of the sequence according to the method of the individual steps when starting up an internal combustion engine is as follows:

• 1. The ignition is switched on,
• 2. at the same time the Beauschlagung begins with predetermined current I _A ;
• 3. The starter is actuated and
• 4. the engine is started (cranking);
• 5 The speed of the engine starts up;
• 6. After reaching a predetermined speed and / or a predetermined time and / or a predetermined oil pressure threshold, the predetermined current I _{A is} turned off;
• 7. The engine is operated in normal operation with camshaft adjuster and / or means for varying the timing, ie the usual operating current I _B is given to the valve.

• 1. Die Zündung wird eingeschaltet,
• 2. gleichzeitig beginnt die Beauschlagung mit vorgegebenem Strom I_A;
• 3. Der Anlasser wird betätigt und
• 4. der Motor wird gestartet (cranking);
• 5. Es erfolgt der Drehzahlhochlauf des Motors;
• 6. Nach Erreichen einer vorgegebenen Drehzahl und/oder einer vorgegebenen Zeit und/oder eines vorgegebenen Öldruckschwellwerts wird der vorgegebene Strom I_A abgeschaltet;
• 7. Der Betrieb des Motors wird noch ohne Nockenwellenversteller und/oder Vorrichtung zum Verändern der Steuerzeiten betrieben;
• 8. Es erfolgt eine Impulsbestromung mit Zusatzstrom I_Z, der so gewählt ist, dass er keinen Einfluss auf die mechanische Bewegung des Nockenwellenverstellers und/oder der Vorrichtung zum Verändern der Steuerzeiten hat;
• 9. Der Motor wird in normalem Betrieb mit Nockenwellenversteller und/oder Vorrichtung zum Verändern der Steuerzeiten betrieben, d. h. der übliche Betriebsstrom I_B wird dem Ventil aufgegeben.

An expanded second example of the procedural sequence is as follows:

• 1. The ignition is switched on,
• 2. at the same time the Beauschlagung begins with predetermined current I _A ;
• 3. The starter is actuated and
• 4. the engine is started (cranking);
• 5. The speed start-up of the motor takes place;
• 6. After reaching a predetermined speed and / or a predetermined time and / or a predetermined oil pressure threshold, the predetermined current I _{A is} turned off;
• 7. The operation of the engine is still operated without camshaft adjuster and / or device for varying the timing;
• 8. There is a pulse current with additional current I _Z , which is chosen so that it has no influence on the mechanical movement of the camshaft adjuster and / or the device for changing the timing;
• 9. The engine is operated in normal operation with camshaft adjuster and / or means for varying the timing, ie the usual operating current I _B is given to the valve.

LIST OF REFERENCE NUMBERS

1

Camshaft adjusting device

2

Vehicle electrics or electronics

3

hydraulic directional valve

4

Means for applying the predetermined current

5

inner rotor

6

outer rotor

7

high pressure pump

8th

hydraulic line

9

hydraulic line

10

Speed sensor

I

electricity

I _A

given current

I _B

operating current

I _Z

additional power

t

Time

t _i

Time of switching on (ignition on)

t _C

Timing of cranking

t _B

Time of normal operation

n

Engine speed

n ₀

specified speed

Claims (13)

Method for operating a hydraulically operated camshaft adjusting device ( 1 ) or a hydraulically operated device for changing the timing of gas exchange valves of an internal combustion engine of a vehicle, wherein the internal combustion engine by a vehicle electrical or electronic ( 2 ) and wherein the device comprises at least one electrically actuated hydraulic valve ( 3 ) for influencing the flow of hydraulic oil through the device ( 1 ), characterized in that the at least one valve ( 3 ) at the start of the internal combustion engine before reaching the idle speed with a predetermined current (I _A ) is applied, wherein an oil pressure of the hydraulic oil is below the operating oil pressure, the camshaft adjusting ( 1 ) needs to operate. Method according to claim 1, characterized in that the at least one valve ( 3 ) from the time (t _I ) of switching on the Fahrzeu dielektrik or electronics ( 2 ) or directly after this time with the predetermined current (I _A ) is applied. A method according to claim 1, characterized in that the predetermined current (I _A ) is constant over time. A method according to claim 1, characterized in that the predetermined current (I _A ) is variable over time. A method according to claim 4, characterized in that the time course of the predetermined current (I _A ) corresponds to that in the later operation (I _B ) during the adjustment of the camshaft or when changing the timing of the gas exchange valves. A method according to claim 4, characterized in that the time course of the predetermined Current (I _A) to that of a PWM signal (pulse width modulation) corresponds. A method according to claim 6, characterized in that the time profile of the predetermined current (I _A ) according to a PWM signal (pulse width modulation), a time-variable current is superimposed with a second frequency. Method according to claim 1, characterized in that the admission of the valve ( 3 ) is terminated with the predetermined current (I _A ) as soon as the internal combustion engine has reached a predetermined speed (n ₀ ), and that the valve ( 3 ) from this time on with the operating current ( 18 ) is applied during the adjustment of the camshaft or when changing the timing of the gas exchange valves. Method according to claim 1, characterized in that the admission of the valve ( 3 ) is terminated with the predetermined current (I _A ), as soon as a predetermined time has elapsed, and that the valve ( 3 ) from this time on with the operating current ( 18 ) is applied during the adjustment of the camshaft or when changing the timing of the gas exchange valves. Method according to claim 1, characterized in that the admission of the valve ( 3 ) is terminated with the predetermined current (I _A ), as soon as a predetermined oil pressure is reached in the internal combustion engine, and that the valve ( 3 ) is acted upon from this point on the operating current (I _B ) during the adjustment of the camshaft or when changing the timing of the gas exchange valves. Method according to claim 1, characterized in that the valve ( 3 ) at least in predetermined time intervals whenever an end position of the camshaft adjusting device ( 1 ) or the device for changing the timing of the gas exchange valves is reached, with a predetermined additional current (I _Z ) is applied. A method according to claim 11, characterized in that the predetermined additional current (I _Z ) consists of short current pulses. A method according to claim 12, characterized in that the current pulses of the predetermined additional current (I _Z ) are selected so that the camshaft adjusting device or the device for changing the timing of the gas exchange valves causes no adjustment.

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