FR2834119A1 - ELECTROMAGNETIC ACTUATOR WITH TWO STABLE LIMIT POSITIONS, IN PARTICULAR FOR CONTROLLING AIR INLET DUCT VALVES FOR INTERNAL COMBUSTION ENGINES - Google Patents

Abstract

The invention relates to an electromagnetic actuator comprising a stator structure (2) consisting of two ferromagnetic circuits (3, 4) provided with at least one electrical excitation coil (5, 5A; 6, 6A) and between which is mounted movably , between two stable end-of-travel positions (8, 9) and against the action of elastic return means (10), an armature (7) in soft ferromagnetic material connected to a load to be controlled. This actuator is characterized by the fact that the armature (7) and the stator structure (2) are symmetrical with respect to an axis (12) corresponding, moreover, to the axis of rotation of the armature (7). The present invention will find an application more particularly in the context of the control of the combustion air intake duct valve of an internal combustion engine.

Description

internal combustion.

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  The invention relates to an electromagnetic actuator comprising a stator structure consisting of two ferromagnetic circuits for wsd 'at least one electric excitation coil and between which is mounted movable, between two stable end positions and against the action of means of resilient return a frame made of soft ferromagnetic material

connected to a load to be controlled.

  The present invention will find its application in the field of electromagnetic actuators more particularly intended to bring a load, simply, from a first in a second

position and vice versa.

  In many fields of application there is the problem of bringing a load, very often in the form of a flap or valve, into two stable end positions, one opening and one closing. It is. in particular, in the case of an internal combustion engine comprising a combustion air intake pipe which, under certain conditions, must be closed to prevent the entry of air into the engine or, conversely,

  completely open to allow free passage of airflow.

  In fact, this management of the combustion air inlet is generally effected by means of the control of the intake valves which comprises such an engine and it is known for these particular applications solenoid electromagnetic actuators or pallet. These solutions, however, remain very complex and have a direct implication on the constituent elements of such a motor.

internal combustion.

  If there are, moreover, electromagnetic actuators of rotary type for these same applications, they are considered, in most cases, as particularly bulky and / or complex with respect to the function they are asked to insure. In addition, they cause parasitic forces

at the level of the load commanded.

  It is still known from US-A.6.262.498, an electromagnetic actuator comprising two electromagnets arranged in opposition relative to each other and between which is able to move a frame of ferromagnetic material

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  maintained in an intermediate position by means of resilient return means, more particularly in the form of a torsion spring. Thus, depending on the electromagnet that is energized, the armature is pulled in one or other of its stable end positions against the action of these elastic return means. To this frame is connected a transmission rod located in the axial extension of a valve of an internal combustion engine,

  valve which it is secured.

  To return to the electromagnets, these comprise a substantially "U" shaped ferromagnetic circuit on which is mounted an electric excitation coil, this circuit defining two stator poles against which it is possible to be

  electromagnetically bonded said armature.

  In the context of a first inventive step, it has been found that the control in displacement of the armature under the impulse of one or the other electromagnet, generates parasitic forces on this frame and in particular of radial forces which deteriorate the efficiency of this actuator, in that they do not

  not allow to optimize the ratio torque / driving inertia.

  In addition, such parasitic forces make the management of the operation of the actuator somewhat more complex, taking into account that according to the intended applications, such as the control of an air intake valve for an internal combustion engine, the we often try to obtain a very fast displacement of the commanded load and it is therefore necessary to manage the inertia of this load, whether at the beginning of the order or at the end of the race where it is necessary, in particular, to control the impact speed of

the frame to the collage.

  In the end and in a second inventive step, it has been thought that the problem of parasitic forces at the level of such an actuator can be remedied by making it symmetrical with respect to the axis of pivoting of the armature, which is itself even symmetrical by

report to this axis.

  For this purpose, the invention relates to an electromagnetic actuator comprising a stator structure consisting of two ferromagnetic circuits provided with at least one coil

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  IEC 60050 - International Electrotechnical Vocabulary - Details for IEV number 841-21-21 Electromagnetic excitation and between which is mounted movable, between two stable end - of - stroke positions and against the action of resilient return means, an armature of soft ferromagnetic material connected to a load to be controlled, characterized in that the reinforcement and the stator structure are symmetrical with respect to an axis corresponding, moreover, to the axis of rotation of

the frame.

  According to an advantageous embodiment, the elastic return means are designed capable of acting on the axis of rotation of

the frame.

  In particular, the elastic return means are defined by a spiral spring acting on the axis of rotation of the armature and mounted in a plane parallel to the stator structure. The advantages that flow from the present invention consist in that, through the symmetry of the stator structure, an equilibrium of parasitic forces results in the control of the actuator, besides the fact that such a configuration makes it possible to optimize the ratio torque / driving inertia. Furthermore, this design, in combination with suitable resilient return means, leads to a compact actuator, thus reduced size for better integration in the environment where the load to be controlled. Another advantage resulting from the suppression of the radial forces consists in an increased longevity of the

  different parts making up this actuator.

  Other objects and advantages of the present invention

  will appear in the following description relating to

  to embodiments given as indicative examples and

non-limiting.

  The understanding of this description will be facilitated by

  with reference to the accompanying drawings in which: - Figure 1 is a schematic representation and a plan view of an electromagnetic actuator according to the invention; FIG. 2 is a representation similar to FIG. 1 illustrating this same actuator equipped with resilient return means in the form of a spiral spring;

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  FIG. 3 is a schematic and perspective representation of this spiral spring; FIG. 4 is a schematic and plan view of the actuator without its support structure; FIG. 5 is a schematic and plan representation of an actuator according to a second embodiment; - Figure 6 is a schematic and elevational representation of an electromagnetic actuator according to the invention which is associated with a position sensor of the armature; FIGS. 7 and 8 schematically illustrate two types of valve valves provided capable of being controlled through an electromagnetic actuator, in accordance with FIG.

the invention.

  The present invention relates to an electromagnetic actuator 1, a first embodiment of which is illustrated in the figures

  1 to 4 and a second in Figure 5.

  More particularly, this actuator 1 comprises a stator structure 2 constituted by two ferromagnetic circuits 3, 4, each comprising at least one electrical excitation coil 5,

AT; 6, 6A.

  Between these two ferromagnetic circuits, arranged opposite one another, is mounted a frame 7 of soft ferromagnetic material. This is caused to move between two stable end positions 8, 9, under the influence of the magnetic flux generated through one and / or the other circuits

ferromagnetic 3, 4.

  In the end, this armature 7 moves in this position 8 or 9 against the action of resilient biasing means 10 tending, in the absence of magnetic flux, to maintain it in an intermediate position, between these positions of ends. 8, 9. According to the invention, said armature 7 is rotatably mounted about an axis 12 corresponding to its axis of symmetry, knowing, moreover, that the stator structure 2 and, in particular, the

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  ferromagnetic circuits 3, 4 adopt, themselves, a provision

  symmetrical with respect to this axis 12.

  Thus, each of these ferromagnetic circuits 3; 4 have four stator poles P1, P2, P3, P4; P'1, P'2, P'3, P'4 with which is cooperated two by two (P1, P2, P'3, P'4, P'1, P'2, P3, P4) the frame 7 in one of its stable positions

end of stroke 8, 9.

  In sum, each ferromagnetic circuit 3, 4 is moreover

  symmetrical with respect to a median plane 13 passing through the axis 12.

  More particularly, a ferromagnetic circuit 3, 4 has a W-shaped configuration whose, according to the embodiment corresponding to FIGS. 1 to 4, the two lateral branches 14, 15, defining the stator poles of ends P1, P4; P'1, P'4

  each carrying an electric excitation coil 5, 5A; 6, 6A.

  While the median branch 16 of this W structure, it detaches the two central stator poles P2, P3; P'2, P'3 respecting, between them, an angle at least equal to the amplitude of rotation of the frame 7, plus 180. Finally, this angle a is the one respected by the two planes in which are inscribed the stator poles, respectively, P1, P2; P'1, P'2 and P3, P4;

  P'3, P'4 of these ferromagnetic circuits 3, 4.

  It will be noted that, for better circulation of the magnetic fluxes, the median branch 16 adopts a V-shaped structure and, consequently, subdivides itself into two branches 16 ',

  16 '' for the definition of the poles P2, P3; P'2, P'3.

  As for the armature 7, in the form of a blade, it comprises, at its axis of rotation 12, a cylindrical blister 17 in the manner of a sleeve for the passage of an axis 18, which may or may not be a ferromagnetic material, the ends 19, 20 are maintained in rotation through a support structure 21, preferably non-magnetic. This is. more particularly,

visible in Figure 6.

  On this structure 21 are still fixed circuits

  ferromagnetic 3, 4 via appropriate means.

  The elastic return means 10 are constituted, preferably, by at least one spiral spring 22, 22 'mounted on

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  at least one of the ends 19, 20 of the axis 18 corresponding to

the frame 7.

  Thus, as can be seen in FIG. 3, this spiral spring 22, 22 'may be provided with one or more spiral-shaped arms, this S depending on the desired stiffness and / or the available space, so the

section of this spring 22, 22 '.

  Referring now to FIG. 5, there is shown a second embodiment of an electromagnetic actuator 1 according to the invention. In fact, it differs from the embodiment described above in that the ferromagnetic circuits 3, 4, while being arranged symmetrically about the axis of rotation 12 of the frame 7 and while having, moreover, a symmetry with respect to a transverse median plane passing through this axis 12, each comprises only one electric excitation coil 5, 6. This is mounted on the middle branch 16 of these ferromagnetic circuits 3, 4 in the form of W. However, it will be observed that in this particular case this median branch 16 terminates in a point through two inclined planes corresponding to the central poles P2, P3; P'2, P'3 and respecting an angle at least equal to the amplitude of rotation of the frame 7, plus 180. In these conditions and to ensure proper circulation of the magnetic flux through the frame

  7, it is mounted on an axis 18 of ferromagnetic material.

  For example, on either side of the blade, defining this armature 7, can extend axis sections held in rotation through the support structure 21 of material

non-magnetic actuator 1.

  FIG. 6 is intended to illustrate that on one of the ends 19 of the axis of rotation 18 corresponding to the frame 7 may be mounted a position sensor 23, preterentially a non-contact sensor with a hall effect, or potentiometer or other type, to know the position of this armature 7 at any time, to control, via an electronic control control unit 24, the switching of the current in the coils and of

  to minimize the impact speed at the end of the stroke of this armature 7.

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  In this respect, if we come back to the embodiment corresponding to FIGS. 1 to 4, the coils 5 and 6A, as well as 5A and 6, ferromagnetic circuits 3 and 4 are connected in series or in parallel, allowing when the bonding of the armature 7 is performed, that is to say when this armature 7 is called in one or other of its end positions 8, 9, of

  to balance the radial forces applied on the axis of rotation 18.

  Thus, the balance of forces applied to this axis is zero.

  Moreover, it will be noted that this axis of rotation 18 corresponding to the armature 7 is held at its ends 19, 20 by bearings or, ideally, by ball or needle bearings which the support structure 21 comprises to limit the friction. In this connection, thanks to the suppression of the radial forces on the axis of rotation 18, as mentioned above, it

  resulting in increased longevity of these bearings or bearings.

  To return to the power supply of the electric excitation coils in the embodiment corresponding to these figures 1 to 4 and starting from the intermediate position 11 occupied by the armature 7 of the actuator 1 at rest, the activation alternatively of the two sets of coils 5, 6A and 5A respectively, 6 makes it possible, in a first step, to bring the armature 7 into a ferromagnetic material when bonded with the stator poles P1, P2, P'3, P'4; P'1, P'2, P3, P4 in an end position 8, 9 predetermined by the selected electrical control. Note that the alternative activation of the coils according to the resonance mode of the system makes it possible to perform this operation in a time dependent on the

current used.

  In a second step, this alternative activation of the two sets of coils 5, 6A; 5A, 6 allows the passage of a position of

end of race to another.

  It should be noted that in these end - of - travel positions 8, 9 the armature 7 does not necessarily come to the physical bonding on the stator poles, as the case may be, P1, P2, P'3, P'4 or P ' 1

  P'2, P3, P4, especially in the presence of external mechanical stops.

  These stops may correspond, for example, to the arrival at the end of the mechanical stroke of the controlled load. By avoiding, therefore,

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  impacts of the armature 7 on these stator poles is limited wear of the electromagnetic actuator 1, besides that it avoids the noise resulting from such impacts. In addition damping means may be associated with the load itself to limit the noise resulting from mechanical stops. In the context of the embodiment corresponding to the figure, that is to say when the electromagnetic actuator comprises only two coils 5, 6, they are connected in series or in parallel and their activation according to the position of the armature 7 allows the passage of a stable end-of-travel position to another depending on the electrical control envisaged. Note, however, that in an intermediate position of the frame 7 no magnetic element is preferred so that this frame 7 can not be driven. Also and according to the invention, an asymmetry is introduced at the level of the resulting actuator, according to a first example of embodiment, of an asymmetric shape of the armature 7 or else by an adapted preload of the spring or springs defining the elastic return means 10 so that this armature 7, in the rest position of these elastic return means 10 and in the absence of supply of the coils 5, 6, occupy an intermediate equilibrium position 11 which is asymmetrical by relative to the median plane 25 of the structure

  stator of this electromagnetic actuator 1.

  Figures 7 and 8 schematically illustrate two types of valves or flaps 26, 26A corresponding to charges that can be controlled by the electromagnetic actuator 1 according to the invention. In fact, it will find a particular application for controlling the opening and closing of the valve of a valve, such as a valve for combustion air intake duct in an internal combustion engine. Thus, Figure 7 shows a first variant having an axis of rotation 27 of the valve 26 which is offset from its plane. This has the consequence of substantially increasing the inertia of the load to be actuated with respect to any other valve, in particular of the butterfly type corresponding to FIG. 8, whose axis of rotation 28 is

located in the plane of the valve 26A.

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  Although the invention has been described with respect to a particular embodiment, it is understood that it is in no way limited and that various modifications of shapes, materials and combinations thereof may be made. various elements without departing from the scope and spirit of the invention.

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Claims (15)

claims   Electromagnetic actuator comprising a stator structure t2) consisting of two ferromagnetic circuits (3, 4) for ws of at least one electric excitation coil (5, 5A, 6, 6A) and between which is mounted movably, between two stable end - of - travel positions (8, 9) and against the action of resilient return means (10), an armature (7) made of a soft ferromagnetic material connected to a load to be controlled, characterized in that the armature ( 7) and the stator structure (2) are symmetrical about an axis (12) corresponding, moreover, to the axis of rotation of the frame (7).   2. Electromagnetic actuator according to claim 1, characterized in that each ferromagnetic circuit (3, 4) comprises four stator poles (P1, P2, P3, P4, P'1, P'2, P'3, P'4 ) with which is cooperated two by two (P1, P2, P'3, P'4, P'1, P'2, P3, P4) the armature (7) in one or other of its   stable end positions (8, 9).   3. Electromagnetic actuator according to any one of   preceding claims, characterized in that a circuit   ferromagnetic (3, 4) is symmetrical with respect to a median plane   (13) passing through the axis of symmetry (12).   4. Electromagnetic actuator according to any one of   preceding claims, characterized in that the poles   stator (P1, P2; P'1, P'2), on the one hand, and the stator poles (P3, P4; P'3, P'4), on the other hand, register, for each circuit ferromagnetic (3, 4), in planes respecting each other an angle (") at least equal to the amplitude of rotation of the frame (7) plus 180.   5. Electromagnetic actuator according to any one of   preceding claims, characterized in that a circuit   ferromagnetic (3, 4) has a W-shaped configuration, the two lateral branches (14, 15) detinating end stator poles (P1, P4, P'1, P'4) each carrying a coil electrical excitation (5, 5A, 6, 6A) while the branch 11 283411 9   median (16) detinits two central stator poles (P2, P3, P'2, P'3). 6. Electromagnetic actuator according to claim 5, characterized in that the middle branch (16) adopts a V-shaped structure and is divided into two branches (16 ', 16' ') for the definition of the central stator poles (P2 , P3, P'2, P'3). 7. Electromagnetic actuator according to any one of   Claims 4 to 6, characterized in that the coils   electrical excitation circuits (5, 6) and (5A and 6A) of the ferromagnetic circuits (3, 4) are connected in series or in parallel in order to symmetrize the radial forces applied on the axis of rotation of the armature ( 7) when the latter is called in one or   the other of these limit positions (8, 9).   8. Electromagnetic actuator according to any one of   Claims 1 to 4, characterized in that a circuit   ferromagnetic (3, 4) has a W-shaped configuration with two lateral branches (14, 15) and a middle branch (16) carrying an electrical excitation coil (5; 6), the middle branch (16) ending at a point through two inclined planes corresponding to the central poles (P2, P3; P'2, P'3) respecting an angle (a) at least equal to the amplitude of   rotation of the frame (7) plus 180.   9. Electromagnetic actuator according to claim 8, characterized in that the electric excitation coils (5, 6) of the ferromagnetic circuit (3, 4) are connected in series or in parallel. 10. Electromagnetic actuator according to claim 8 or 9, characterized in that the armature (7) has an asymmetrical shape with respect to its axis of rotation (12) or the elastic return means (10) have a suitable preload for conferring on said armature (7) a position in intermediate equilibrium (11), in the rest position of these elastic return means (10) and in the absence of supply of the coils (5, 6), 283411 9   which is asymmetrical with respect to the median plane (25) of the stator structure t2).   11. Electromagnetic actuator according to any one of   preceding claims, characterized in that the armature   (7) is in the form of a blade rotatably mounted on an axis (8) of ferromagnetic material or not, the ends (19, 20) of which are held in rotation through a non-magnetic support structure (21) on which are still fixed circuits   ferromagnetic (3, 4) via appropriate means.   12. Electromagnetic actuator according to any one of   preceding claims, characterized in that the means   resilient recalls (10) are designed to act on the axis of rotation (12) of the armature (7).   Electromagnetic actuator according to claims 11   and 12, characterized in that the elastic return means (10) consist of at least one spiral spring (22, 22 ') mounted on at least one of the ends (19, 20) of the spindle (18). ) corresponding to the frame (7).   14. Electromagnetic actuator according to any one of   claims 11 to 13, characterized in that on one of the   ends (19) of the axis of rotation (18) corresponding to the armature (7) is mounted a position sensor (23), more particularly a non-contact sensor with hall effect or other, for controlling, via a electronic control control unit (24), switching on the current in the coils (5, 5A; 6, 6A) and minimize the speed   end of stroke impact of the armature (7).   15. Application of the electromagnetic actuator according to one   any of the preceding claims, at the control of a flapper   of combustion air intake duct valve of a combustion engine.