WO2007093692A1

WO2007093692A1 - Method for controlling start-up of an actuating member of a valve electromechanical actuator

Info

Publication number: WO2007093692A1
Application number: PCT/FR2007/000235
Authority: WO
Inventors: Emmanuel Talon; Nicolas Gelez
Original assignee: Valeo Systemes De Controle Moteur
Priority date: 2006-02-17
Filing date: 2007-02-09
Publication date: 2007-08-23
Also published as: FR2897716A1; FR2897716B1

Abstract

The invention concerns a method for controlling start-up of a mobile actuating member of a valve electromagnetic actuator, the actuating member (4, 5) being mobile between two extreme positions under the action of at least one electromagnet (6) opposite which extends a blade (5) secured to the actuating member to be selectively attracted towards one or the other of the extreme positions, and a spring member (7) defining a position for balancing the actuating member intermediate between the extreme positions; transitions of the actuating member from one of the extreme position constituting a starting position to the other of the extreme positions constituting an arrival position are provided, when the actuating member is maintained counter to the spring member by the electromagnet in starting position, by modulating a feeding current of said electromagnet to cause the actuating member to start under the action of the spring member towards the arrival position. According to the invention, the method includes a step of adapting the modulation of the feeding current such that the actuating member has a travelling speed (Vm) in one controlling position substantially equal to a nominal travelling speed (Vnom).

Description

Method for controlling the start of an actuating member of an electromechanical valve actuator

The invention relates to a method for controlling the departure of an actuating member of an electromagnetic valve actuator.

BACKGROUND OF THE INVENTION Electromagnetic valve actuators are known which comprise an actuating member of the valve which is movable between two extreme positions under the action of at least one electromagnet opposite which extends a solid pallet the actuating member to be attracted selectively towards one or the other of the extreme positions, and a spring member defining a position of equilibrium of the actuating member intermediate between the extreme positions.

Such actuators are powered to cause transitions of the actuating member of one of the extreme positions forming a starting position to the other end positions forming an arrival position by proceeding, while the body of The actuation is maintained against the spring member by one of the electromagnets in the starting position, at a modulation of a supply current of this electromagnet to cause a departure of the actuating member. under the action of the spring member to the position of arrival.

During such transitions, the actuator then moves the valve from an open position corresponding to one of the extreme positions of the actuating member to a closed position corresponding to the other of the extreme positions of the actuator member. actuation, and vice versa.

In general, the modulations of the supply current consist, for the electromagnets without permanent magnets for holding the pallet, to abruptly cancel the holding current of the pallet, or, for the electromagnets provided with permanent magnets, maintaining the pallet, to abruptly turn up the supply current of the electromagnet to a level for which the flow of one electromagnet against the flux of the permanent magnet so that the pallet is no longer maintained.

However, experience shows that these operating conditions can lead to impact speeds of the actuating member when it reaches one or the other of the extreme positions which may vary during the course of the operation. time .

The speed of arrival may be greater than expected, which may give rise to impact noises which, without being dangerous, may be unpleasant. On the contrary, the arrival speed may be lower than expected, which requires supercharging the electromagnet that attracts the actuating member to its position of arrival, generating excessive current consumption.

OBJECT OF THE INVENTION

The object of the invention is a method for managing the actuator that avoids the aforementioned drawbacks.

BRIEF DESCRIPTION OF THE INVENTION With a view to achieving this object, it is proposed according to the invention to adapt the modulation of the supply current during the departure of the actuating member so that the actuating member has a speed of passage in a control position substantially equal to a nominal passage speed.

Thus, by modifying the modulation of the power supply current of the electromagnet which holds the pallet, the work of electromagnetic forces acting on the pallet is modified substantially over the first half of the stroke of the actuating member. which makes it possible to compensate for the work of the elastic forces and the external forces to rebalance the latter and thus to match the speed of passage of the actuating member in the control position to the desired nominal passage speed. Thus, by calibrating the speed of passage of the actuating member in the control position, the mechanical energy of the actuating member is calibrated, which makes it possible to guarantee that the actuating member will reach in the end position with a speed close to a nominal impact speed, and thus to avoid at the same time unwanted impact noise and over-consumption of current.

Preferably, the control position is in the vicinity of the equilibrium position defined by the springs. In this position, the mechanical energy of the actuating member comprises only kinetic energy and is therefore directly proportional to the square of the speed of passage of the actuating member in the control position, so it is possible to directly calibrate the mechanical energy of the actuator without taking into account the potential energy developed by the springs.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood in the light of the description which follows with reference to the figures of the appended drawings among which:

- Figure 1 is a schematic sectional view of an electromagnetic valve actuator known per se;

FIG. 2 is a graph showing the supply current modulation of the electromagnet holding the pallet in one of the extreme positions as a function of time; - Figure 3 is a graph showing a block diagram of a servo implementing the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, an electromagnetic actuator 1 known per se is mounted on a cylinder head 2 combustion engine for operating a valve 3 mounted movably on the yoke 2 along the X axis between an open position and a closed position.

The actuator comprises a member of ^one actuator, here a movably mounted plunger 4 along the axis X. The pusher 4 is secured to a pallet 5 which extends between two electromagnets 6.

Springs 7 recall the ends facing the pusher 4 and the valve 3 towards each other and define an equilibrium position of the valve / pusher / pallet assembly (hereinafter referred to as a moving assembly) in which the pallet 5 extends substantially midway electromagnets 6 (as shown here).

Each of the electromagnets 6 comprises a core 8 for channeling an electromagnetic flux generated by an associated coil 9 so that the flow closes in the pallet 5 and attracts it towards the end face 10 of the corresponding core 8. The stop of the pallet 5 against the end faces 10 of the cores 8 defines extreme positions respectively corresponding, for the upper electromagnet 6, to the closed position of the valve 3, and for the lower electromagnet 6, in the open position of the valve 3.

Here, the electromagnets 6 are equipped with permanent magnets 11 to hold the pallet 5 in abutment against the end face 10 of the associated core 8 without the associated coil 9 being energized. For this purpose, the permanent magnets 11 are arranged in the core 8 so that the flow of the permanent magnets 11 can be channeled through the core to close in the pallet 5.

The actuator is controlled by a computer 50 which supplies the coils 9 of the electromagnets β to cause transitions of the valve between the closed position and the open position, and vice versa. Starting for example from the closed position in which the pallet 5 is held in abutment against the end face 10 of the core of the upper electromagnet 6, which will be called for the electromagnet starting sequence, the computer 50 performs a modulation of the feed current of the coil 9 of the starting electromagnet so that the coil 9 generates a magnetic flux that against the magnetic flux of the permanent magnets 11, so that the magnetic force exerted on the pallet 5 by the starting electromagnet is not enough impor - both to hold the moving assembly against the springs 7.

The pallet 5 is then released, and the springs 7 propel the movable assembly 3/4/5 to the lower electromagnet, or incoming electromagnet. The pallet then arrives on the end face 10 of the core of the incoming electromagnet with a certain impact velocity Vi, so that the impact gives rise to an impact noise.

FIG. 2 illustrates, by curve 100, the nominal modulation of the feed current of the coil of the starting electromagnet performed by the computer 50. This modulation consists, starting from a zero level, in increasing abruptly. the supply current at a nominal level. The supply current is maintained at the nominal level for a time substantially equivalent to the duration of the pallet to travel half a race between the extreme positions. Then the feed stream is suddenly reduced to zero level.

For various reasons, the impact velocity of the pallet on the core of the incoming electromagnet may vary and be out of an acceptable impact velocity range. If the impact speed is too great, it gives rise to an unwanted impact noise. If, on the other hand, the speed of impact is too low, the arrival electromagnet must develop a greater effort, which leads to over-consumption of current.

Different causes are responsible for the variation of the impact velocity. For example, it may be that the equilibrium position is not strictly midway between the extreme positions defined by the electro-magnets, so that the pallet arrives more quickly on the electromagnet whose corresponding extreme position is closer to the equilibrium position. It is also possible that disturbances such as thermal expansion, friction, affect the operation of the actuator and vary the speed of impact. These disturbances evolve little from one transition to another so that they can be considered, over a period of a few transitions, as constants.

Other disturbances have a much faster evolution. This may be for example the back pressure exerted on the valve head and varies greatly during the same transition. According to the invention, the first part of the stroke of the moving assembly 3/4/5 is acted upon by adapting the current modulation 100 of the starting electromagnet so that, in view of the foreseeable disturbances, the speed of the impact remains within a range of acceptable speeds.

For this purpose, the computer 50 measures the speed Vm of the moving assembly when it moves into a control position substantially at halfway, that is to say in the vicinity of the equilibrium position defined by Springs. The computer 50 receives the signal from a displacement sensor 12 (visible in FIG. 1) which measures the position of the pusher 4, for example a hall effect sensor cooperating with a small magnet placed on the pusher 4, the drifting computer 50 the signal of the displacement sensor 12 according to digital techniques known per se to obtain an estimate of the passage velocity Vm in the control position halfway.

Consider the case where the half-travel speed Vm thus estimated is greater than a nominal passage speed Vnom, the computer 50 is programmed, according to the invention, to estimate a correction 102 of the current modulation. supplying the coil 9 to the electromagnet 6 starting in a direction tending to reduce the speed of impact to come. As can be seen in FIG. 2, the correction 102 consists in reducing the level of the supply current of the coil 9 by passing it from the nominal level to a corrected level lower than the nominal level, as illustrated in FIG. by the curve 101 in dashed lines. The decrease in the supply current causes a decrease in the flux of the coil 9 (which nevertheless remains sufficient to counteract the flux of the permanent magnets 11 so that the pallet 5 can take off from the starting electromagnet under the action of the springs 7 ).

The sum of the fluxes of the coil 9 and the permanent magnets 11 is thus greater than during the nominal power supply, this sum of flux therefore generates on the pallet 5 an additional magnetic force which produces a supplementary work resistant which has the effect of slowing the pallet 5 so that it arrives against the core 8 of the incoming electromagnet with a reduced impact speed.

On the contrary, when the measured velocity in the control position is lower than the nominal velocity Vnom, the computer 50 is programmed to correct the modulation of the supply current of the coil 9 to the starting electromagnet 6 in a meaning tending to increase the speed of impact to come. The correction then consists of increasing the level of the power supply tation of the coil 9 from the nominal level to a corrected level higher than the nominal level.

With reference to FIG. 3, the correction is carried out according to the invention by the implementation of a servo-control of the PID type 51 which, starting from a difference ε _v between the measured speed Vm and the nominal speed Vnom deduces a correction to be made to the nominal current modulation. This type of servocontrol is very well adapted to take account of slow disturbances. To take account of the faster disturbances, the computer implements a predictor 52 which, by means of a numerical model which estimates the rapid disturbances (in particular the backpressure acting on the valve 3), makes it possible to modify the correction determined by PID 51 to account for the effect of these rapid disturbances on the future transition.

By adding the correction 102 thus determined to the nominal modulation 100, the computer 50 determines the supply current i. corrected to provide to the starting electromagnet.

Of course, the correction thus determined takes into account only repeatable disturbances, that is to say the disturbances that are predictable. It has been considered here that non-repeatable disturbances are negligible. However, if this is not the case, it is then possible to take into account at least partially the effect of the non-repeatable disturbances by the following means: the computer 50 is programmed to record the behavior of the moving assembly 3 / 4/5 during a previous transition, for example by keeping in memory samples of the signal of the displacement sensor 12 during the previous transition.

With the aid of the numerical model mentioned above, the calculator 50 estimates the repetitive disturbances (in particular the against the pressure acting on the valve 3) having influenced the previous transition, and removes the effect of these repetitive disturbances from the previous recorded transition. The residual difference between the transition thus treated and the transition recorded is then due to the non-repeatable disturbances that were not taken into account in the model.

It is then assumed that for the upcoming transition, the effect of the non-repeatable disturbances will be identical, and this effect is taken into account to adjust the correction 102 to be applied to the current modulation 100.

The invention is not limited to what has just been described, but on the contrary encompasses any variant falling within the scope defined by the claims.

In particular, although we have taken the example of a transition of the moving assembly from the extreme position associated with the upper electromagnet towards the extreme position associated with the lower electromagnet, it goes without saying that the The invention also applies to inverse transitions.

In addition, although by way of example, the modulation of the feed stream illustrated here consists of a simple change from a zero level to a non-zero and constant nominal level, the modulation may take any other form. Similarly, although the correction contemplated here takes the form of an addition to the nominal ^• level of a current increment (positive or negative), the correction may take any other form.

Although in order to determine the correction to be applied to the modulation of the supply current of the starting electromagnet, the speed of passage of the preceding transition is used, it will of course be possible to use the speeds of passages of several other transitions pre- for example by averaging the speeds of passage of the five or ten previous transitions. In addition, although the control position in which the speed is measured here is a position in the vicinity of the equilibrium position defined by the springs, we can take any other control position on the stroke of the moving assembly.

Although the invention has been illustrated in connection with an actuator whose electromagnets comprise permanent magnets, the invention also applies to an actuator whose electromagnets do not include permanent magnets. In this case, the modulation generally consists in causing the feed current of the starting electromagnet to suddenly switch from a maintenance level to a zero level. In this case, the correction may consist of changing the supply current from the maintenance level to a non-zero level.

Finally, although the invention has been illustrated in connection with an actuator with two permanent electromagnets, the invention applies to a single electromagnet actuator adapted to draw the pallet selectively towards one or other of the electromagnets. extreme positions.

Claims

1. A method of managing the departure of a movable actuating member of an electromagnetic valve actuator, the actuating member (4, 5) being movable between two extreme positions under the action of at least an electromagnet (6) facing which extends a pallet (5) integral with the actuating member to be attracted selectively towards one or other of the extreme positions, and a spring member (7). ) defining an equilibrium position of the member of ^one actuating intermediate between the extreme positions; transitions from the actuating member of one of the extreme positions forming a position of de- part in the other extreme position forming an inlet positions being caused by following, while the actuating member is d ¹ maintained against the spring member by the electromagnet in the starting position, a modulation (100) of a supply current of the electromagnet to cause a departure of the actuating member under the action the spring member to the arrival position; said modulation of the supply current being adapted so that the actuating organ ¹ has a passage speed (Vm) in a control position substantially equal to a nominal speed of passage (Vnom), characterized in that the position of control is taken in the vicinity of the equilibrium position defined by the spring member.

2. The method of claim 1 wherein, to adapt the modulation of the supply current for the upcoming transition, is added to a nominal modulation (100) a correction (102) depending on a difference (ε _v ) between the nominal speed (Vnom) and a measured velocity (Vm) of passage in the control position from to least a previous transition.

3. The management method as claimed in claim 2, in which, to estimate the correction (102), it is predicted (52) an effect of repetitive disturbances which are capable of disturbing the speed of the actuator during the coming transition.

The management method according to claim 3, wherein, to estimate the correction (102), a non-repeatable disturbance effect which affected at least one previous transition is taken into account.

5. The management method as claimed in claim 4, in which, in order to estimate the effect of the non-repeatable disturbances, the effect of the repetitive disturbances which affected this transition is removed from the preceding transition.