Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/06—Electromagnets; Actuators including electromagnets
  • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
  • H01F7/14—Pivoting armatures
  • H01F7/145—Rotary electromagnets with variable gap

Definitions

• the present invention relates to a single phase rotary electromagnetic actuator.
• the actuator In certain applications, in particular for controlling the recirculation or air intake valve, it is desirable for the actuator to return to a determined rest position.
• the torque actuators due to the constant current of the state of the art are generally coupled in their applications with a return spring which allows, in the event of a cut in the electrical supply to the actuator, close the air intake valve to cut off the air supply to the heat engine.
• a return spring is bulky, presents risks of rupture and its return torque must be adjusted relative to the position of the valve.
• the object of the invention is to remedy these drawbacks by proposing an actuator comprising means for returning to the simple rest position, inexpensive, and requiring no adjustment.
• the actuator comprises a fixed member constituted by a stator circuit excited by at least one electric coil, and a member movable in rotation comprising a thin magnet having 2N pairs of magnetic poles magnetized in alternating directions.
• the actuator further comprises return means for bringing the movable member to a predetermined angular rest position constituted by a thin auxiliary return magnet disposed in the air gap, having 2N pairs of magnetic poles magnetized in an alternating direction and integral with the stator poles.
• the rotor poles and the magnetic poles of the auxiliary return magnet are in the form of thin annular sectors.
• the rotor poles and the magnetic poles of the auxiliary return magnet are of tubular shape.
• the auxiliary return magnet is bonded to the stator poles in a position such that the equilibrium position without current of the rotor corresponds to the position without current sought.
• the rotor cooperates with the fixed member by means of a ball stop limiting the movement of the rotor in the direction of the fixed organ.
• the ball bearing is substantially coplanar with the plane passing through the end of the stator poles.
• the 2N-pole magnetic disc constituting the auxiliary magnet has a central recess with a section at least equal to the section of the ball bearing.
• the rotor magnet is integral with a cylinder head made of a soft magnetic material.
• the stator further comprises a fixed closing yoke made of a soft magnetic material.
• the invention also relates to a valve, in particular an air intake valve for an internal combustion engine, driven by such an actuator.
• the auxiliary return magnet will be arranged so that the rest position corresponding to a partial opening of the air intake.
• FIG. 1 shows an exploded view of an actuator according to the invention
• FIG. 3 represents a view in median section of an actuator according to the invention
• - Figure 4 shows a top view of one actuator
• - Figure 5 shows a cross-sectional view of an alternative embodiment.
• FIG. 1 represents an exploded view of a first embodiment of an actuator according to the invention.
• the actuator is made up of a fixed part (1) and a mobile part in rotation (2).
• the fixed part (1) has 4 stator poles (3 to 6) in the form of annular sectors each excited by an electric coil (7 to 10).
• the stator poles (3 to 6) are extended by cores surrounded by the electric coil (7 to 10), these cores being integral with a base (11).
• the statori ⁇ ue structure is known and is not explained in more detail.
• the rotor part (2) has 4 magnetic poles formed by thin magnets (12 to 15) in the form of annular sectors magnetized in alternating directions, perpendicular to the transverse plane of the annular sectors.
• the magnetized sectors (12 to 15) are bonded to a yoke (16). This cylinder head is mounted on an axis not shown.
• the actuator comprises a second series of magnetized annular sectors (17 to 20) in alternating directions. These magnetized annular sectors (17 to 20) form an auxiliary return magnet bonded to the stator poles (3 to 6).
• FIG. 2 represents the torque curves as a function of the angular position of such an actuator.
• the curves (70 to 72) correspond to the torque as a function of the position, for a current of 1.5, 1 and 0.5 amps respectively.
• the curve (31) represents the torque in the absence of current, for a displacement of the rotary member (2) in the trigonometric direction.
• the curve (32) represents the torque in the absence of current, for a displacement of the rotary member (2) in the anti-direction trigonometric
• the curves (74 to 76) correspond to the torque as a function of the position, for a current of respectively - 1.5, - 1 and - 0.5 amps.
• the cylinder head (35) has a cylindrical housing (38) provided with a bearing (39).
• the stato ⁇ que part (1) has a bearing (36).
• the positioning and guiding of the cylinder head (35) is ensured by a ball bearing (37) interposed between the two bearings (36, 39)
• the cylinder head (35) is integral with an axis (40) passing through an orifice provided in the base (41).
• This orifice (42) has a section greater than the section of the axis (40) so that this axis is never guided by the staton ⁇ ue part.
• the positioning, and in particular the centering of the axis results solely from the magnetic positioning. by the magnetic cooperation of the main magnet (43) with the stator poles (44), and the limitation of the axial displacement due to the ball bearing (37) the stator poles are excited in known manner by coils (50, 51 ).
• the auxiliary return magnet (45) is bonded to the stator poles.
• Figure 4 shows a top view of 1 actuator previously described.
• the magnetization transitions (52, 53) of the main magnet are angularly offset, in the rest position, relative to the magnetization transitions (54 to 57) of the main magnet.
• FIG. 5 represents another alternative embodiment relating to an actuator with a tubular rotor.
• the actuator is composed of a stator (60) excited by two electric coils (61, 62) defining a cylindrical cavity inside which is placed a rotor (63) having two semi-tubular magnets (64, 65) magnet radially in opposite directions. These magnets (64, 65) are bonded to a yoke (66).
• the stator comprises two semi-tubular auxiliary magnets (66, 67) magnetized radially in opposite directions housed in the central cavity, in the tubular air gap

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)
• Electrically Driven Valve-Operating Means (AREA)
• Valve-Gear Or Valve Arrangements (AREA)
• Indication Of The Valve Opening Or Closing Status (AREA)
• Magnetically Actuated Valves (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9488188

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (3)

Family Cites Families (6)

• 1996
  • 1996-01-17 FR FR9600496A patent/FR2744559B1/fr not_active Expired - Fee Related
• 1997
  • 1997-01-16 DE DE69738708T patent/DE69738708D1/de not_active Expired - Lifetime
  • 1997-01-16 JP JP9508717A patent/JP2000503165A/ja active Pending
  • 1997-01-16 WO PCT/FR1997/000080 patent/WO1997026667A1/fr active IP Right Grant
  • 1997-01-16 AT AT97900660T patent/ATE396486T1/de not_active IP Right Cessation
  • 1997-01-16 EP EP97900660A patent/EP0886875B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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