Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
  • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
  • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
  • F01L9/21—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by solenoids
  • F01L2009/2132—Biasing means
  • F01L2009/2134—Helical springs
  • F01L2009/2136—Two opposed springs for intermediate resting position of the armature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
  • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
  • F01L9/21—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by solenoids
  • F01L2009/2146—Latching means
  • F01L2009/2148—Latching means using permanent magnet

Definitions

• the invention relates to an electromagnetic permanent magnet valve actuator.
• An electromagnetic valve actuator is known, for example from document JP-A-08 004546, comprising a movable actuator under the effect of an elastic member and at least one coil. , and at least one permanent magnet arranged so as to retain the actuating member in at least one of the extreme positions against the elastic member when the coil is not energized.
• the coil is associated with a core comprising two parts having first surface portions in contact with the permanent magnet.
• One of the core parts has a protrusion which extends parallel to the magnetization direction of the magnet towards the other core part so as to define on the two core parts second surface portions spaced apart by an air gap having a dimension much less than the thickness of the permanent magnet.
• This outgrowth forms a bypass which channels most of the coil flux, only a residual flux passing through the permanent magnet, which protects it from the risk of demagnetization.
• the second portions of surfaces extend adjacent to the sides of the permanent magnet, in a direction parallel to the first portions of surface, so that the air gap extends parallel to the direction of magnetization of 1 permanent magnet.
• This arrangement has the drawback of imposing an increase in the size of the actuator in a direction perpendicular to the direction of the magnetization of the permanent magnet.
• the subject of the invention is an electromagnetic actuator for a permanent magnet and bypass valve having a reduced overall size.
• valve actuator of the aforementioned type in which the air gap between the second surface portions of the two core parts forms an angle with the direction of magnetization of the permanent magnet.
• FIG. 1 is a sectional view of an actuator according to the invention installed on an engine cylinder head, illustrating the magnetic flux flowing in the actuator during the phase of attraction of the pallet against the core;
• Figure 2 is a view similar to that of Figure 1, illustrating the magnetic flux flowing in the actuator during the pallet holding phase;
• the actuator 10 of the invention comprises a non-magnetic housing mounted on a cylinder head 4 of an engine for actuating a valve 1.
• the actuator 10 comprises a pusher 11 which slides coaxial with the valve stem 1.
• the end of the valve stem 1 and the end of the plunger 11 are biased towards each other by two opposing springs 12 and 13 acting respectively on the plunger 11 and on the stem of the valve 1.
• the springs 12, 13 define an equilibrium position of the pusher 11 in which the valve is in a half-open position.
• the pusher 11 is integral with a pallet 14, made of ferromagnetic material, movable inside a cavity 15 produced in a ferromagnetic core 16 composed of two core parts 17.
• the cavity 15 defines an upper active face 18 and a lower active face 19 extending over the two core parts 17.
• the actuator is single-coil, and one of the core parts 17 extends through the single coil 20.
• the two core parts 17 comprise on the one hand first surface portions 21 which are in contact with the faces of a permanent magnet 22, and on the other hand second surface portions 23 which extend in look at each other with an air gap e much less than the thickness H of the permanent magnet 22.
• the operation of the actuator is as follows. We assume here that palette 14 is closer from the upper active face than from the lower active face, so that at the start the magnetic fluxes which close in the pallet pass through the upper active face. When during its movement the pallet is closer to the lower active face, the magnetic flux closes in the pallet passing through the lower active face, which has the consequence of attracting the pallet towards this face.
• the coil 20 is supplied so that it generates a magnetic flux 30 in the same direction as the magnetic flux 32 of the permanent magnet 22, as illustrated in FIG. 1 .
• the magnetic flux 30 generated by the coil 20 passes through the pallet 14 via the upper active face 18, and transits from one part of the core to the other, almost entirely passing through the second surface portions 23, due to the very small air gap e between the second surface portions 23, compared to the distance H separating the first surface portions 21.
• the magnetic flux 30 generated by the coil 20 adds its effects to the magnetic flux 32 generated by the permanent magnet 22 which, when the gap between the pallet 14 and the upper active face 18 becomes lower than the gap e, transits in the core parts 17 via the first surface portions 21 and closes in the pallet 14.
• the supply to the coil 20 can be cut, or even reversed in order to control the speed of docking of the pallet 14 against the upper active face 18.
• the active face portions in contact with the pallet have areas smaller than the area of the faces of the permanent magnet 22, which causes a concentration of the flux which tends to increase the attraction force exerted by permanent magnet 22 on pallet 14
• the coil 20 is supplied to generate a reverse magnetic flux 31, in the opposite direction to the magnetic flux 32 generated by the permanent magnet 22.
• the reverse magnetic flux 31 generated by the coil 20 therefore closes in the opposite direction to that of FIG. 1 and then at least partially compensates for the flux 32 of the permanent magnet 22 so that the attraction force exerted on the pallet 14 is no longer sufficient to counteract the force of the spring 12.
• the pallet 14 then leaves the upper active face 18.
• the flux generated by the coil 20, whether it is in the same direction or opposite to the flux 32 of the permanent magnet 22, therefore passes through the second surface portions 23, which thus form in the core 16 a magnetic path for this flux which passes out of the permanent magnet 22 (except for losses).
• the permanent magnet 22 is therefore subjected at most to a marginal part of the flux generated by the coil 20, this marginal part being in any event much less than the flux necessary to demagnetize the permanent magnet 22 , including when the coil 20 is supplied with high currents.
• the air gap e must be large enough to prevent the flow of the permanent magnet from being closed by the second surface portions 23, but small enough to decrease losses of flux from the coil which pass through the first surface portions through the permanent magnet.
• the second portions of surfaces 23 are here arranged relative to the permanent magnet so that the air gap e is perpendicular to a direction of magnetization 25 of the permanent magnet 22.
• the second surface portions 23 extend towards the inside of the actuator 10. The first surface portions and the second surface portions 23 thus extend perpendicular to each other.
• the magnet extends parallel to the plane of installation of the actuator on the cylinder head 4, between an upper horizontal branch 26 and a lower horizontal branch 27 belonging respectively to the one of the core parts 17 and each carrying one of the first surface portions 21.
• Each of the horizontal branches is connected in a general L-shape to a vertical branch 28 whose lower end is shaped to present the active faces upper 18 and lower active faces 19.
• the permanent magnet 22 thus has a width almost equal to the width of the core, reduced only by the thickness of the vertical branch connected to the upper horizontal branch, and by a clearance corresponding to the air gap e. This arrangement gives the first surface portions 21 in contact with the permanent magnet 22 particularly large dimensions.
• the invention has been illustrated with reference to a single-coil pallet actuator with linear displacement, the invention also applies to a single-coil pallet actuator with rotary displacement, as well as bi-coil actuators with pallet with linear or rotary movement, in which at least one coil is associated with at least one permanent magnet and with a core defining a magnetic path for the flux of the coil passing out of the permanent magnet.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electromagnets (AREA)
• Magnetically Actuated Valves (AREA)
• Valve Device For Special Equipments (AREA)
• Fluid-Driven Valves (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=32406399

Family Applications (1)

Country Status (7)

Families Citing this family (4)

Family Cites Families (8)

• 2002
  • 2002-12-23 FR FR0216518A patent/FR2849262B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-19 AT AT03799640T patent/ATE414978T1/de not_active IP Right Cessation
  • 2003-12-19 EP EP03799640A patent/EP1576627B1/de not_active Expired - Lifetime
  • 2003-12-19 WO PCT/FR2003/003808 patent/WO2004061875A2/fr active Application Filing
  • 2003-12-19 US US10/540,017 patent/US20070025047A1/en not_active Abandoned
  • 2003-12-19 DE DE60324838T patent/DE60324838D1/de not_active Expired - Lifetime
  • 2003-12-19 JP JP2004564292A patent/JP2006511953A/ja not_active Ceased

Non-Patent Citations (1)

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