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
  • F01L2009/2146—Latching means
  • F01L2009/2148—Latching means using permanent magnet

Definitions

• Electromagnetic actuator of permanent magnet double-coil valve is Electromagnetic actuator of permanent magnet double-coil valve.
• the invention relates to an electromagnetic valve actuator with a permanent magnet.
• an electromagnetic valve actuator with permanent magnet having an actuator movable between two extreme positions under the effect of an elastic member and two electromagnets each comprising a core which comprises a first T-shaped core part comprising a base connected to a central branch around which a coil is disposed, the first core part being placed in a second part of U-shaped core having a base and outer arms which extend parallel to the central arm of the first T-core part, a permanent magnet being interposed between the base of the first core part and the base of the second part of core.
• the valve actuators are required to operate at temperatures between about 100 and 200 degrees Celsius.
• the magnetization / demagnetization cycle of the permanent magnets exhibits a significant hysteresis, so that at these temperatures the flux required to demagnetize the permanent magnet is lower than the flux necessary to magnetize the permanent magnet.
• there is therefore a risk that the intensity of the alternating flux generated by the electromagnet passing through the permanent magnet is above the demagnetization threshold thereof, all ' by being below the magnetization threshold, which leads to the progressive demagnetization of the permanent magnet during the operation of the actuator.
• This demagnetization leads to a reduction in the capacity of the magnets to hold the pallet in the extreme positions, and to an increase in the electrical consumption of the electromagnets which must compensate for the loss of force exerted by "the permanent magnets.
• the object of the invention is to provide a permanent magnet actuator comprising a bypass of the permanent magnet for the flow of the coil while avoiding the aforementioned drawbacks of the ISUZU document.
• an actuator of the aforementioned type for which, in at least one of the electromagnets, the base of the first T-shaped core part extends to present with the outer branches of the second part.
• U-shaped core of air gaps having a dimension much less than a distance between the base of the first part of T-shaped core and the base of the second part of U-shaped core.
• the air gaps of the bypass thus produced no longer extend parallel to the direction of magnetization of the permanent magnet, but perpendicular thereto.
• This arrangement allows the bypass to be carried out by simple extension of the base of the first T-shaped core part, which is particularly simple to manufacture and does not increase the size of the actuator.
• FIG. 1 is a sectional view of an actuator according to the invention installed on an engine cylinder head, in a neutral position of the actuator;
• FIG. 2 is a partial symbolic sectional view of the actuator according to the invention illustrating the flows flowing in the actuator during the phase 'of attraction of the pallet towards the core;
• a two-wire electromagnetic actuator 10 comprises a non-magnetic housing 16 mounted on a cylinder head 4 of an engine for actuating a valve 1.
• the tail 3 of the valve 1 is mounted to slide in a bearing 5 of the cylinder head 4.
• the actuator 10 comprises a pusher 11 which slides coaxially with the valve stem.
• the end of the shank 3 of the valve 1 and the end of the pusher 11 are brought back towards each other by two opposing springs 12 and 13 acting respectively on the push-button 11 and on the shank 3 of the valve .
• the springs 12 and 13 define an equilibrium point of the pusher 11, in which the valve is in the half-open position.
• the pusher 11 is integral with a pallet 14 mounted to move between two electromagnets 15 (which will be detailed later).
• the stroke of the pusher 11 is thus limited between an upper extreme position defined by the stop of the pallet 14 against the core of the upper electromagnet 15 and a lower extreme position defined by the stop of the pallet 14 against the core of the electromagnet 15 lower, the two extreme positions corresponding to the open position and the closed position of the valve 1.
• the pusher 11 In operation, the pusher 11 is moved 'from one extreme position to the other by the combined action of the springs 12 and 13 and the electromagnets 15 alternately attracting the pallet 14.
• each of the electromagnets 15 comprises a core comprising a first core portion 18 having the general shape of a T ⁇ , having a base 19 and a central leg 20 around which a coil 21 is arranged. Furthermore, the core has a second core portion 22 having the general shape of a U, comprising a base 23 as well as two outer branches 24 which extend parallel on either side of the central branch 20 of the first part of core 18.
• the first core part 18 is arranged in the second core part 22, a permanent magnet 25 being interposed between the base 19 of the first core part 18 and the base 23 of the second core part 22.
• the base 19 of the first core part 18 makes with the outer branches 24 of the second core part 22 air gaps e having a dimension much less than the distance between the base 19 of the first core part and the base 23 of the second part of the nucleus.
• the ends of the outer branches 24 of the second core part 22 and of the central branch 20 of the first core part 18 form portions of an active face 26 of the core of the electromagnet forming a stop for the pallet 14.
• the coil 21 is fed so that it generates a flux 29 in the same direction as the flux 27 of the permanent magnet 25, like this is illustrated in FIG. 2.
• the flow 29 generated by the coil 21 passes through the central branch 20 of the first core part, passes to the outer branches 24 of the second core part via the pallet 14 which it attracts and closes on the base 19 of the first core part passing almost entirely through the air gaps (e) due to the very small dimension of these relative to the distance between the base 19 of the first core part and the base 23 of the second core part ,. Only the losses close to the central branch 20 of the first core part passing through the base 23 of the second core part and through the permanent magnet 25. The air gaps thus form a magnetic path for the magnetic flux generated by coil 21.
• the flow 29 generated by the coil 21 then adds its effects to that of the flow 27 of the permanent magnet 25 to attract the pallet 14 towards the active face 26.
• the magnetic flux 29 generated by the coil 21 can be reversed in order to control the speed of approach of the pallet 14 against the active face 26.
• the flux 27 generated by the permanent magnet 'NENT 25 passes through the base 23 and the outer legs 24 of the second core part 22 by the central leg 20 of the first core portion 18 and closes in the pallet 14.
• the flux 27 of the permanent magnet 25 is then strong enough to keep the pallet 14 in abutment against the core of the electromagnet 15 against the spring 12 (not shown here).
• the cross section of the magnetic flux from the permanent magnet 25 of the core in the pallet 14 is less than the area of the faces of the permanent magnet 25, which causes a concentration of the flux which tends to increase the force of attraction exerted by the permanent magnet 25 on the pallet 14.
• the coil 21 is supplied to generate a flux 28 opposite to the flux 27 from the permanent magnet 25.
• the flux 28 generated by the coil 21 closes in the opposite direction to that of FIG. 2 and then at least partially compensates for the flux 27 of the permanent magnet 25 so that the attraction force exerted on the pallet 14 is no longer sufficient to counter the spring force 12.
• the pallet 14 then leaves the active face 26 of the core of the electromagnet 15.
• the flux generated by the coil 21, whether in the same direction or opposite the flow 27 of the permanent magnet 25, therefore passes through the first core part and the second core part without passing through the permanent magnet 25, except for losses.
• the permanent magnet 25 is therefore subjected at most to a marginal part of the flux generated by the coil 21, this marginal part being in any state of 'cause much lower than the flux required to demagnetize the permanent magnet 25, including when the coil 21 is supplied with high intensity currents.
• the air gaps e must be large enough to prevent the flow of the permanent magnet 25 from closing in the base 19 of the first core portion 18 rather than. in the pallet 14, but the air gaps must not be too large so as to minimize the losses of the flux generated by the coil 21 which pass through the permanent magnet.
• the invention has been described with the two electromagnets 15 fitted with permanent magnets 25, in order to be able to hold the valve in each of the extreme positions, the invention can be carried out with a single electromagnet fitted with a 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)
• Reciprocating, Oscillating Or Vibrating Motors (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=32406401

Family Applications (1)

Country Status (5)

Families Citing this family (10)

Family Cites Families (10)

• 2002
  • 2002-12-23 FR FR0216520A patent/FR2849101B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-19 WO PCT/FR2003/003807 patent/WO2004061276A1/fr not_active Ceased
  • 2003-12-19 JP JP2004564291A patent/JP2006512039A/ja active Pending
  • 2003-12-19 US US10/540,015 patent/US20070025046A1/en not_active Abandoned
  • 2003-12-19 EP EP03799639A patent/EP1576260A1/de not_active Withdrawn

Non-Patent Citations (1)

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