WO2009034252A2

WO2009034252A2 - Method for powering an electromagnetic actuator according to two powering configurations and corresponding actuation device

Info

Publication number: WO2009034252A2
Application number: PCT/FR2008/000995
Authority: WO
Inventors: Boris Bouchez; Emmanuel Talon
Original assignee: Valeo Systemes De Controle Moteur
Priority date: 2007-07-13
Filing date: 2008-07-09
Publication date: 2009-03-19
Also published as: FR2918787B1; WO2009034252A3; FR2918787A1

Abstract

The invention relates to a method for powering an electromagnetic actuator (1) that comprises a fixed member (2) and a mobile member (6) having facing portions respectively provided with permanent magnets (7) and coils (4), wherein the method comprises the step, in a nominal powering configuration, of simultaneously powering all the coils at the same current intensity for moving the mobile member on a distance covering a stable balance position resulting from the nominal powering configuration, the method also comprising the step of powering a portion of the coils simultaneously at the same current intensity in a palliative powering configuration, to which corresponds a stable balance position different from the nominal operation configuration. The invention also relates to a corresponding device.

Description

Method of supplying an electromagnetic actuator according to two power supply configurations and corresponding actuating device

The present invention relates to a method of supplying an electromagnetic actuator and a corresponding actuating device.

BACKGROUND OF THE INVENTION Such an electromagnetic actuator is, for example, usable for the actuation of motor vehicle thermal engine valves.

It is known electromagnetic actuators comprising, firstly, a fixed member consisting of an armature provided with a plurality of coils and, secondly, a movable member or core provided with permanent magnets arranged opposite the coils . The coils are generally associated with a control unit arranged to feed the coils according to the desired displacement of the movable member. There are various types of actuators ¹ and especially linear actuators in which the moving member slides with respect to the fixed member, alternative circular actuators in which the moving member oscillates with an angular displacement with respect to the fixed member and rotary actuators, such as motors, in which the movable member pivots with respect to the fixed member.

There are also different ways of feeding the coils. The most advanced mode is based on an individualized supply of coils for successively feeding all or part of the coils according to the displacement to be made, efforts to implement, the speed to reach ... These modes of supply required - However, they try to use sophisticated and expensive control units.

In some applications that do not require the performance of this advanced mode of supply, a simpler mode of supply is used, in which all the coils are fed simultaneously with the same intensity of current in order to generate electromagnetic fields producing on the coils. the movable member of the forces which will be added in a resultant force capable of moving the movable member on a predetermined stroke. A disadvantage of this mode of supply is that, when the coils are all powered simultaneously, there will exist in the race of the movable member a stable equilibrium position in which the coils exert on the movable member a resultant force zero or low insufficient to move the movable member. If the movable member arrives in this stable equilibrium position with insufficient speed, it stops and it is no longer possible to move it by feeding the coils. This does not pose a problem as long as the speed of passage of the movable member in equilibrium stable position is sufficient and, when the movable member must have intermediate stopping positions in its race, if one makes sure these intermediate stop positions are sufficiently far from the stable equilibrium position.

However, in certain applications which have been envisaged for these actuators, and in particular the actuation of automobile engine thermal engine valves, and under certain circumstances, there is an increase in the resistance to displacement of the actuator. mobile. This is the case when the lubricant used to reduce the frictional resistance of the valve during its displacement has an increased viscosity due for example to a low ambient temperature. The lubricant viscosity introduces additional resistance to the movement of the valve, and therefore the movable member, which makes it more difficult to obtain an acceleration of the movable member which would allow it to reach a sufficient speed of passage in the stable equilibrium position.

The only solution considered is to increase the intensity of the current used to feed the coils. However, this results in an increase in the electrical consumption of the vehicle and a necessary resizing of the coils may increase the weight and bulk.

OBJECT OF THE INVENTION

An object of the invention is to provide a means to overcome this disadvantage.

SUMMARY OF THE INVENTION

For this purpose, there is provided, according to the invention, a method of supplying an electromagnetic actuator comprising a fixed member and a movable member which have facing parts provided respectively with permanent magnets and coils, the method comprising step, in a nominal power configuration, simultaneously supplying all the coils with the same current intensity to move the movable member on a path covering a stable equilibrium position resulting from the nominal power supply configuration, the method comprising the step of supplying a portion of the coils simultaneously with the same intensity of current in a palliative supply configuration to which corresponds a stable equilibrium position different from that of the nominal operating configuration.

Thus, each power configuration corresponds to a different stable equilibrium position so that it is possible to use one or the other of these configurations depending on the position and speed of the movable member in its race.

According to a particular embodiment, in order to move the movable member over its travel, the coils are first supplied in the nominal supply configuration to the corresponding stable equilibrium position, then in the palliative configuration. supply to pass said stable equilibrium position, then in the nominal power configuration to finish the move.

The simultaneous supply of all the coils makes it possible to obtain the greatest acceleration of the movable member, the palliative feed configuration being used only to facilitate the passage of the movable member in the equilibrium position. stable corresponding to the nominal power supply configuration.

The invention also relates to an actuating device for implementing this method. The actuating device comprises an electromagnetic actuator comprising a fixed member and a movable member which have facing parts provided respectively with permanent magnets and coils, the coils being associated with a control unit having:

a nominal supply configuration in which the control unit simultaneously supplies all the coils with the same intensity of current in order to move the movable member over a race extending on either side of an equilibrium position; of the movable member resulting from the nominal supply configuration, a palliative supply configuration in which the control unit simultaneously feeds a portion of the coils with the same current intensity to move the movable member on at least one part of the race, and to which corresponds a position of equi- stable free of the movable member different from that resulting from the nominal power supply configuration.

Preferably, the device comprises a deactivating element of at least one of the coils, connected to the control unit for deactivating said at least one of the coils when the control unit is in the palliative supply configuration.

Thus, the control unit controls the deactivation element to obtain the deactivation of the coil or coils that will not be powered in the palliative supply configuration. This embodiment is particularly simple and requires an inexpensive deactivation element such as a relay or a transistor. Other features and advantages of the invention will become apparent from reading the following description of particular non-limiting embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made to the appended drawings, among which:

FIG. 1 is a diagrammatic sectional view of a linear actuation device according to a first embodiment of the invention,

FIG. 2 is a diagram showing the evolution of the resulting force exerted by the coils on the movable member during its displacement,

FIG. 3 is a schematic sectional view of an alternative circular actuating device according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, the actuator according to the first embodiment of the invention comprises an electromagnetic actuator generally designated 1. The electromagnetic actuator 1 comprises an armature comprising a frame 2 having two opposite sides from which extend, projecting towards the inside of the frame 2, branches 3, namely a central branch and two external branches arranged on either side of the branch Central. Coils 4 extend around the outer branches 3.

The branches 3 of the two opposite sides have free ends facing each other in pairs and enlarged, defining between them a passage for a movable member to know a core 6. The core 6 is formed of a plate incorporating permanent magnets 7 which extend parallel to the free ends of the legs 3 and which are spaced by non-magnetic portions 8. The core 6 is connected to a valve stem 9 by means known per se in such a way that a displacement of the core 6 in its sliding direction causes a corresponding displacement of the valve.

The coils 4 are connected to a source of electrical power supply 10 controlled by a control unit 11 arranged to control the supply of the coils 4 in current and adjust the intensity delivered. Two of the coils 4 facing each other, here the coils 4 carrying the index "a" in FIG. 1, are connected to the supply source 10 via an actuating element 12. here constituted by a relay or a transistor and connected to the control unit 11. The control unit 11 is also connected to a position sensor 13 of the valve which indirectly supplies the position of the core 6. control unit 11 is thus arranged to control the supply of the coils 4 according to two power supply configurations:

a nominal supply configuration in which the four coils 4 are activated and are supplied with the same intensity of current, a palliative supply configuration in which the coils 4.a are deactivated and only the coils 4.b are activated and fed by the same intensity of current.

In Figure 2, there is shown the race of the core 6 and the stable equilibrium positions Pl, P2 respectively corresponding to the nominal configuration and the palliative configuration.

In normal operation, the control unit 11 is in nominal power configuration. In the case of a cold start, detected for example by measuring the outside temperature, a measurement of the viscosity or temperature of the lubricant of the valve, the control unit 11 is in the nominal feed configuration up to the pallet arrives in the vicinity of the position Pl and then in the palliative feed configuration so that the core 6 passes the position Pl. Once the core 6 is sufficiently far from the position Pl, the control unit 11 returns at the nominal power supply configuration. If it is necessary to stop the core 6 in an intermediate position close to the stable equilibrium position P1, the nominal supply configuration is used to bring the core 6 to the intermediate position and stop it there and the configuration palliative to initiate a new core movement 6. Once the core is sufficiently far away from the stable equilibrium position P1, the nominal power configuration is again used.

As a variant, it is possible to provide for the control unit 11 to be placed in a palliative feed configuration if the speed of the core 6 (obtained by derivation of the position signal) is insufficient to safely pass the stable equilibrium position. Pl or alternate configurations in a systematic way as long as the cold start conditions remain. According to a second embodiment, shown in Figure 3, the actuating device ¹ according to the invention comprises an oscillating circular actuator generally designated 21 having an armature 22 in an arc inside which are mounted the reels 23. A movable member, namely a rotating core 24 having an outer surface provided with permanent magnets 25, is mounted to pivot in the armature opposite the coils 23. The coils 23 are connected to a power supply 26 in electrical energy itself connected to a control unit 27. Some coils 23, marked with the index "a" are connected to the power source 26 via a deactivation element 28 itself connected to the control unit 27 to be controlled by it.

The control unit 27 comprises two power supply configurations, namely:

a nominal supply configuration in which all the coils 27 are supplied with the same intensity of current,

a palliative supply configuration in which the coils 23. connected to the deactivation element 28 have been deactivated and only the other coils, marked by the index "b", are supplied with the same current intensity.

At the nominal configuration and the palliative supply configuration correspond two stable equilibrium positions angularly offset with respect to each other. The operation of the control unit is identical to that of the first embodiment.

Of course, the invention is not limited to the embodiment described and variants can be made without departing from the scope of the invention as defined by the claims. In particular, the invention is applicable to actuators having a structure different from that described and for example to rotary motors.

The control unit may be the Valve Control Unit (VCU) or the Engine Control Unit (ECU).

Alternatively, the control unit may have one or more power supply configurations and one or more power supply configurations.

The mode of transition between the nominal supply configuration and the palliative supply configuration may be different from that described.

Other applications of the invention are conceivable.

Claims

A method of supplying an electromagnetic actuator (1; 21) comprising a fixed member (2; 22) and a movable member (6; 24) which have facing portions provided respectively with permanent magnets (7; ) and coils (4; 23), the method comprising the step, in a nominal power supply configuration, of simultaneously supplying all the coils with the same intensity of current to move the movable member over a path covering a position stable equilibrium resulting from the nominal supply configuration, characterized in that the method comprises the step of supplying a part of the coils simultaneously with the same intensity of current in a palliative supply configuration to which corresponds a position of stable equilibrium different from that of the nominal operating configuration.

The method according to claim 1, wherein, to move the movable member (6; 24) over its travel, the coils (4; 23) are first fed in the nominal power supply configuration to the position corresponding stable equilibrium, then in the palliative feed configuration to pass said stable equilibrium position, and then in the nominal feed configuration to complete the displacement.

3. The device of ^one actuator comprising an electromagnetic actuator (1; 21) comprising a fixed member (2; 22) and a movable member (6; 24) which have facing portions provided with respective permanent magnets (7; 25) and coils (4; 23), the coils being connected to a control unit (11; 27) having a nominal power configuration in which the control unit simultaneously supplies all the coils with the same current intensity. to move the movable member on a stroke extending on either side of a stable equilibrium position of the movable member resulting from the nominal feed configuration, characterized in that the control unit has a configuration palliative feeding:

in which the control unit simultaneously feeds a part of the coils with the same intensity of current to move the movable member over at least a part of the race, and to which corresponds a stable equilibrium position of the organ different from that resulting from the nominal power supply configuration.

4. Device according to claim 3, comprising a deactivating element (12; 28) of at least one of the coils (4.a, 23. a), connected to the control unit (11; 27) for deactivating said at least one of the coils when the control unit is in the palliative supply configuration.

5. Device according to claim 4, in which the deactivation element (12; 28) is a relay.

6. Device according to claim 4, wherein the deactivation element (12; 28) is a transistor.

7. Device according to claim 3, in which the permanent magnets (7; 25) are carried by the movable member (2; 22).

8. Device according to claim 3, wherein the movable member (6; 24) is slidably mounted relative to the fixed member (2; 22).

9. Device according to claim 3, wherein the movable member (6; 24) is mounted to pivot relative to the fixed member (2; 22).

10. Device according to claim 3, comprising a position sensor (13) of the movable member (6) connected to the control unit (11).