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
• • 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
  • H01F7/081—Magnetic constructions
• • 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
• • 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
  • F01L2301/00—Using particular materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/0302—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity characterised by unspecified or heterogeneous hardness or specially adapted for magnetic hardness transitions
  • H01F1/0306—Metals or alloys, e.g. LAVES phase alloys of the MgCu2-type
• • 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
  • H01F7/16—Rectilinearly-movable armatures
  • H01F7/1638—Armatures not entering the winding

Definitions

• the present invention relates to a valve control device for an internal combustion engine as well as an engine equipped with such a device.
• Valves are essential parts of internal combustion engines. They allow the operation of the latter by alternating two positions: A first position called “open” allows exchanges between the inside and the outside of a cylinder using this valve, for example to inject fuel into this cylinder. A second position called “closed” prevents any exchange between the inside and the outside of this cylinder, for example to allow the compression of injected fuel.
• the valves are actuated by relatively complex mechanical connections with the rest of the engine. In recent times, electrically controlled valve engines have been developed, this control allowing to choose at will the opening and closing times.
• Such a device comprises springs and at least one or two electromagnets, the latter receiving control signals for positioning the valve in the open or closed position.
• a known device of this type is shown in FIG. 1. It comprises a helical spring 12 surrounding a rod 14 integral with a valve 10 and pressing, on one side, against a stop 16 integral with this rod 14 and, on the other hand, against a stop 18 surrounding an opening 20 of the body of the corresponding cylinder 21. With the rod 14 (or valve stem) cooperates another rod 22 carrying a plate 26 of magnetic material. Between the rods 22 and 14, there is a clearance 24 allowing the rod 22 to slide even though the rod 14 remains stationary when the rod 22 is at the end of its stroke upwards in FIG. 1. The plate 26 is installed between two electromagnets 28 and 30 crossed by the rod 22. These two electromagnets 28 and
• the end 32 of the rod 22 which is opposite the link 24 cooperates with the first end of another spring 34.
• the second end of this spring 34 is fixed to a support 36 secured to a frame 37.
• the springs 34 and 12 maintain the plate 26 equidistant from the two electromagnets
• This position can be adjusted by varying the position of the support 36 relative to the chassis 37.
• the electromagnet 28 When the electromagnet 28 is activated, it attracts the plate 26 and the latter comes into contact with part of the magnetic circuit of this electromagnet 28. This displacement causes the rod 22 and the rod 14 to slide along an axis 27 coincident with the axis of these rods - such that the head 38 of the valve 10 is brought to rest on its seat. The valve 10 is then closed.
• the electromagnet 30 When the electromagnet 30 is activated, the latter attracts the plate 26 which comes into contact with part of the magnetic circuit of this second electromagnet, driving the rod 22 and the rod 14 along the axis 27, the head 38 moving away therefore from his seat.
• the valve 10 is then in the open position.
• the springs 12 and 34 are associated with the movement of the rods 14 and 22 by compressing or relaxing according to the movements of the latter, a resonant electromechanical system being thus formed.
• the magnetic circuits 29 and 31 of the electromagnets are of the so-called polarized type, that is to say that they comprise a permanent magnet. This allows a magnetic blocking of the plate 26 in the respectively open or closed position at zero or low current in the electromagnet, respectively 30 or 28.
• the present invention results from the observation that such a control device is not energetically optimized.
• the present invention overcomes these drawbacks. It relates to an electromechanical valve control device for an internal combustion engine, characterized in that the magnetic circuit of the electromagnet and / or the plate include a magnetic material having a remanent magnetization when the valve is in the open or closed position, said remanent magnetization being reversible so as to be canceled upon a change of position of the valve and having a coercive field included between 10 Oersted and 600 Oersted. Materials with remanent and reversible magnetization are also commonly called semi-hard or hysteresis materials.
• the materials used in the invention have a high remanent induction as well as an intermediate coercive field compared to soft materials and hard materials.
• the hysteresis of a magnetic material is defined by two magnetic quantities: the coercive field and the induction.
• the coercive field is often less than 1 Oersted (80 A / m).
• the hysteresis cycle is as wide as possible. It is agreed that the field of permanent magnets begins with materials which have a coercive field of at least 600 Oersted (5000 Ampere per meter).
• the other magnetic quantity, induction B characterizes the capacity to have an induced magnetization. It is understood that it is advantageously as high as possible in one invention.
• a material having a high induction value as well as an intermediate coercive field can thus be magnetized in a remanent and reversible manner.
• the magnetization of the plate and / or the magnetic circuit of the electromagnet can thus be modified. This makes it possible to have a plate and / or a magnetic circuit which is magnetized when the valve is held in position. This holding is therefore possible with zero or weak current in the electromagnet.
• a coercive field value of 10 Oersteds provides correct position hold in valve applications. Such maintenance is not ensured by a simple material having a remanent magnetization of the Hard Steel type (carbon for example) sometimes used. Such residual magnetism is of the type observed with a temporarily magnetized steel part which manages to attract nails, for example. Such a coercive field value also makes it possible to demagnetize the plate and / or the magnetic circuit of the electromagnet just before the transition from one position to another so as not to have to provide significant force during. the transition. Since the magnetization modifications do not require a large amount of energy, the electrical energy consumption of the device is reduced compared to a known device.
• the material having a remanent and reversible magnetization has a coercive field included between 50 Oersted and 500 Oersted.
• a selective coercive field interval particularly suitable for valve applications, ensures good support and minimizes the energy required to demagnetize the material.
• This material is advantageously chosen from Iron-Cobalt-Vanadium alloys or from Alnico (Aluminum-Nickel-Cobalt) alloys with low coercive field.
• the material having a remanent and reversible magnetization is in laminated form. The laminated form is obtained when the material is produced in a strip. This is the case for FeCoVa for example.
• FIG. 1 already described, represents a device known valve control
• Figures 2a, 2b, 2c, 2d and 2e are diagrams illustrating the operation of a control device 1 according to the invention. In the example proposed in FIGS.
• the plate is the element of the device including a material with remanent and reversible magnetization.
• the control device according to the invention includes an electromagnet 28 and a plate 26 which is integral with a valve not shown in Figures 2a to 2e.
• the electromagnet 28 comprises a coil represented by two crosses on the sections presented in FIGS. 2a to 2e and a magnetic circuit 29 made of magnetic material. Without pre-magnetization of the plate 26 and without current in the coil, as shown in FIG. 2a, no force is created between the plate 26 and the electromagnet 28. When the current i in the coil is established, thus as shown in FIG. 2b, a flow Fb is created which magnetizes the plate 26 made of semi-hard material.
• the plate then creates in turn and according to the direction of the current in the coil, a so-called residual flux Fp.
• the remanent flux Fp created by the remanent magnetization of the plate 26 in the magnetic circuit 29 of the electromagnet 28 makes it possible to maintain a significant induction in the magnetic circuit 29 of the electromagnet 28 and therefore generate an electromagnetic force between the plate 26 and the electromagnet 28. This force does not practically depend on the intensity of the current previously applied to the coil.
• the plate 26 can then be held in position with a zero or weak current in the same way as with a plate having permanent magnetization. Upon application of a current in the opposite direction to the current previously applied in the coil, the plate 26 demagnetizes.
• the magnetization of the plate is effected by the flux of the coil each time the plate is attracted by the electromagnet, for example at start-up or during a transition.
• the remanent magnetization of the pallet makes it possible to maintain a significant induction in the magnetic circuit. This makes it possible to obtain a holding force which may be sufficient to obtain holding at zero or low current in the coil.
• a demagnetization current is applied to demagnetize the tray.
• the advantages of the invention are in particular to obtain a blocking in the open or closed position at zero or low current and, at the same time, to allow transitions that are inexpensive in energy since the magnetization can be canceled at the time of the transition.
• the cycle of application of the current to the coil is a function of the cycle desired for the opening and closing of the valve. For example, when according to an embodiment presented above, the positioning of the valve in a second position is obtained by the action of a second electromagnet acting on the plate, the current intended to pass through this second electromagnet is synchronized with the current negative traversing the first electromagnet to demagnetize the plate.
• the transition is inexpensive in energy because the plate is released by the first electromagnet at the moment when it is called upon to move towards the second electromagnet.
• An additional advantage of the invention lies in the fact that the semi-hard materials have a higher apparent permeability than that of the magnets. This therefore generates better efficiency of the coil.
• a device according to the invention does not present a risk of irreversible demagnetization of the plate, such a defect being all the more detrimental in applications requiring high reliability such as a motor.
• the invention has been presented with a plate made of semi-hard material.
• the plate includes a soft magnetic material and the magnetic circuit of the electromagnet includes a magnetic material with remanent and reversible magnetization. It is also possible to envisage that the plate and the magnetic circuit of the electromagnet both include a semi-hard magnetic material.
• the positioning of the valve in a second position can also be achieved by the action of known means, in particular mechanical. In this case, only one position, open or closed, is ensured according to the invention. The other position can for example use a spring.

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• 2004
  • 2004-01-27 FR FR0450152A patent/FR2865498B1/fr not_active Expired - Fee Related
• 2005
  • 2005-01-27 DE DE602005002752T patent/DE602005002752T2/de active Active
  • 2005-01-27 ES ES05717690T patent/ES2290899T3/es active Active
  • 2005-01-27 EP EP05717690A patent/EP1774143B1/de not_active Not-in-force
  • 2005-01-27 AT AT05717690T patent/ATE374882T1/de not_active IP Right Cessation
  • 2005-01-27 US US11/578,317 patent/US7798110B2/en active Active
  • 2005-01-27 WO PCT/FR2005/050051 patent/WO2005075796A1/fr active IP Right Grant

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