Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M51/00—Fuel-injection apparatus characterised by being operated electrically
  • F02M51/06—Injectors peculiar thereto with means directly operating the valve needle
  • F02M51/0603—Injectors peculiar thereto with means directly operating the valve needle using piezoelectric or magnetostrictive operating means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/04—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series
  • F02M61/08—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00 having valves, e.g. having a plurality of valves in series the valves opening in direction of fuel flow
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/167—Means for compensating clearance or thermal expansion
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/70—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger
  • F02M2200/703—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic
  • F02M2200/705—Linkage between actuator and actuated element, e.g. between piezoelectric actuator and needle valve or pump plunger hydraulic with means for filling or emptying hydraulic chamber, e.g. for compensating clearance or thermal expansion

Definitions

• the invention relates to a device for injecting liquid, in particular fuel, of the type comprising an actuator with electroactive material acting on a needle to cause the injection of liquid.
• Document FR 2 854 664 discloses an injection device comprising a tubular body in which a needle is mounted.
• the needle is terminated by a valve head with a seat carried by the end of the tubular body.
• Pressurized fuel feeds the inside of the tubular body and is stopped by the valve.
• the needle has a longitudinal housing in which is placed an electroactive material. When the electroactive material is excited, it elongates, causing the elastic elongation of the needle and thus the detachment of the head relative to the seat.
• the valve is then opened and the fuel passes between the seat and the head to be injected into a combustion chamber.
• the amplitude of the opening of the valve is limited by the possible elongation amplitude of the electroactive material.
• the electroactive material has a maximum elongation of the order of one to one thousand to one percent of its length. To increase the amplitude, it is necessary to increase the length of the bar of electroactive material, which makes the device very bulky.
• Document FR 2 889 257 also discloses an injection device comprising an actuator whose end acts on one end of the needle, opposite the end comprising the head.
• the actuator is contained in a bushing which is slidably mounted and on which resilient spring means act resiliently to maintain the head resting on the seat. This arrangement makes it possible to compensate for the differential expansions that may appear during the operation of the device between the tubular body and the needle. These differential expansions are caused by temperature gradients in the device and expansion properties that vary from one material to another.
• To cause the opening of the valve it causes the resonant axial oscillation of the needle.
• the invention aims at proposing another solution for the injection device to adapt to the differential variations to which the components of the device are subjected. It also aims to provide a device which a large range of displacement of the needle head can be obtained without providing a very long electroactive bar.
• the subject of the invention is a liquid injection device comprising a tubular body, a needle whose one end comprises a valve head on a seat of the tubular body, an actuator with an electroactive material suitable for cause a displacement of the head of the needle to open the valve, a conduit to bring the liquid around the needle to the head, characterized in that it comprises a hydraulic chamber delimited by an actuator piston moved by the actuator and a needle piston, the needle piston being carried by the end of the needle opposite the head , the hydraulic chamber being supplied with fluid through the conduit via a capillary.
• the coupling between the actuator and the needle is thus achieved by the fluid contained in the hydraulic chamber.
• a displacement of the actuator piston is transmitted to the needle piston through the liquid contained in the hydraulic chamber.
• the hydraulic chamber is in communication with the conduit, the differential expansions are compensated by the variation of the volume of liquid contained in the hydraulic chamber.
• capillary it is necessary to understand a channel whose ratio between the diameter and the length is small. This has the consequence that the flow of liquid through the capillary is negligible during the displacement of the actuator piston, and that the movement of the actuator piston is entirely transmitted to the needle piston, because of the incompressibility of the liquid. .
• a decoupling is performed between the actuator and the needle adapted to compensate for the differential expansions.
• the section of the actuator piston is greater than that of the needle piston. Thanks to this characteristic, the movement of the actuator is amplified. Indeed, the displacement of the actuator piston on a first distance moves a volume of liquid, which causes the needle piston to move a second distance. Since the needle section is smaller than that of the actuator piston, the second distance is larger than the first distance. This gives an amplification of the movement of one actuator.
• the device comprises a first guide surface in which the actuator piston is slidably mounted, the guide surface opening into a first decompression chamber opposite the hydraulic chamber.
• a clearance between the guide surface and the piston is necessary. A small amount of liquid therefore passes into this space.
• the first decompression chamber makes it possible to collect the liquid and to prevent the actuator from being subjected to the high pressure of the liquid.
• the device comprises a second guide surface in which the needle piston is slidably mounted, the second guide surface opening into a second decompression chamber opposite the hydraulic chamber.
• the needle comprises a ring attached to the needle and slidably mounted in the tubular body, a first end of the ring being in communication with the conduit, the other end being in contact with the second decompression chamber.
• the first and second decompression chambers are for example interconnected and in communication with a return line which collects the liquid to bring it back to a reservoir.
• an adapter piece is fitted into the tubular body and carries the first and the second guide surface. This arrangement makes it easier to produce the guide surfaces and the pipes or capillaries.
• the actuator is for example a magnetostrictive actuator or an electrostrictive actuator, for example a piezoelectric actuator.
• the device comprises means for supporting the actuator on the tubular body, the support means being selected from hydraulic support means or resilient support means.
• the device comprises holding means in support of the head of the needle on the seat.
• the valve of the device is kept closed except when the actuator acts to open it.
• the holding means comprise a spring bearing on the tubular body and on the needle piston.
• the holding means comprise a magnet generating a magnetic attraction force between the needle piston and the actuator piston.
• FIG. 1 is a sectional view of a device conforming to a first embodiment of the invention
• Figure 2 is a view similar to Figure 1 of a second embodiment of the invention
• Figure 3 is a sectional view of an actuator of the device of Figure 1 in two different states
• Figure 4 is a detail view IV of Figure 1
• Figure 5 is a view similar to Figure 4 of a variant of the device.
• a device 1 for injecting liquid, in particular fuel, according to a first embodiment is shown in FIGS. 1, 3 and 4.
• the injection device 1 comprises a tubular body 11 in which a needle 12 is slidably mounted and which is actuated by the actuator 10.
• the needle 12 comprises at one end a head 120 forming a valve on a seat 110 of the tubular body 11
• the tubular body 11 comprises a supply duct 111 which extends from an inlet 112 into the tubular body 11 and then around the needle
• the inlet 112 is intended to be connected to a not shown device for supplying fuel under high pressure, for example between 500 and 3000 bar.
• the device 1 comprises an adaptation piece
• the device 1 comprises a return line 15 in communication with the housing 16 and intended to be connected with a liquid reservoir, not shown.
• the adapter piece 13 has a first guide surface 131 in which an actuator piston 101 is slidably mounted.
• the actuator piston 101 is the active part of the actuator 10 whose operation will be described later.
• the adapter piece 13 also has a second guide surface 132 in which a needle piston 121, located opposite the head 120, is slidably mounted.
• the actuator piston 101 and the needle piston 121 face each other in a hydraulic chamber 17.
• the section of the actuator piston 101 is greater than that of the needle piston 121.
• the hydraulic chamber 17 is supplied with fluid by the supply duct 111 via a capillary 18, in particular through the wall of the adapter piece 13.
• the first guide surface 131 opens into a first decompression chamber 19 opposite the hydraulic chamber 17.
• the first decompression chamber 19 extends around the actuator piston 101.
• the first decompression chamber 19 is in communication with the housing 16 by a channel 135 passing through the wall of the adaptation piece 13.
• the channel 135 is made for example by a flat on the adapter piece 13 and a bore which connects said flat and the first decompression chamber 19 .
• the portion of the supply duct 111 around the needle 12 is limited to the opposite of the head
• the ring 122 is slidably mounted in the tubular body 11 on a third guide surface 133.
• the second and the third guide surface 132, 133 open into a second decompression chamber 20. the opposite of the hydraulic chamber 17 relative to the needle piston 121.
• the first and second decompression chamber 19, 20 are in communication with each other via a channel 134 which extends longitudinally through the adapter piece 13.
• the actuator 10 comprises a casing 100 of cylindrical shape which contains the active part of the actuator 10.
• the active part comprises the actuator piston 101 abutting a magnetostrictive rod 102, itself abutting a flyweight 103.
• the piston actuator 101 has a shoulder 1010 against which rests an elastic washer 106, itself bearing against another shoulder 1000 of the housing.
• a prestressing spring 104 bears on the casing 100 and compresses against the spring washer 106 the stack formed of the piston 101, the bar 102 and the weight 103.
• the bar 102 is surrounded by an electric winding 105 able to create a magnetic field in the bar 102. The magnetic field causes the elongation of the bar 102, in a manner known per se.
• the elongation of the bar 102 thus controls the displacement d of the actuator piston 101, as represented on the right-hand part of FIG. 3, with a partial crushing of the elastic washer 106.
• By modulating the electric current that supplies power the winding 105 modulates the movement of the actuator piston 101.
• the document FR 2 889 257 describes a similar example of an actuator and its operation.
• Holding means comprises a magnet 124 housed in the needle piston 121 and generating a magnetic attraction force between the needle piston 121 and the actuator piston 101, so as to normally maintain the head 120 in support on the seat 110 and thus to close the valve.
• the injection device 1 When the injection device 1 is in operation, it is fed by the inlet 112 of the feed duct 111 with a liquid such as fuel at a very high pressure, for example between 500 and 3000 bar.
• the pressurized liquid passes through the capillary 18 and fills the hydraulic chamber 17.
• a little liquid passes from the hydraulic chamber 17 to the first decompression chamber 19 passing between the first guide surface 131 and the actuator piston 101. then the housing 16.
• the excess is discharged through the return line 15.
• a little liquid also passes from the hydraulic chamber 17 to the second decompression chamber 20 passing between the second guide surface 132 and the piston of needle 121.
• a little liquid also passes from the supply conduit 111 to the second decompression chamber 20 passing between the third guide surface 133 and the ring 122.
• the excess liquid in the second vacuum chamber passes to the second first decompression chamber 19 through the channel 134.
• the liquid under pressure acts on the mini-jack 14 so as to apply the actuator 10 in support on the adaptation piece 13.
• This bearing force is symbolized by the arrow Fc in FIG.
• the liquid under pressure acts on the one hand on the head 120 of the needle 12 by exerting a force tending to move the head 120 away from the seat 110, and on the other hand on the piston and the ring 122 exerting a force tending to press the head 120 on the seat 110.
• the needle 12 also undergoes the magnetic force which also tends to press the head 120 on the seat 110.
• the diameter of the ring 122 is greater than the diameter of the seat 110, the resultant of these forces also tends to press the head 120 on the seat 110, whatever the pressure of the liquid.
• the needle 12 is also subjected to the pressure of the liquid of the hydraulic chamber 17 which acts on the surface of the needle piston 121.
• the surfaces of the needle piston 121 and the ring 122 are chosen so that the resultant of the hydraulic forces has tendency to press the head 120 on the seat 110, with sufficient force to obtain the closure of the valve, including taking into account the inertial forces and the weight of the needle 12.
• the actuator 10 When it is desired to perform an injection, the actuator 10 is controlled so that the actuator piston 101 slides in the adapter part 13. It then controls the displacement of the liquid contained in the hydraulic chamber 17. The liquid increases pressure to cause a sufficiently large force on the needle piston
• the movement of the actuator piston 101 may be an oscillating movement combined with a mean displacement.
• the device 1 in a variant shown in FIG. 5, in which the holding means are not hydraulic but mechanical, the device 1 "does not have a second decompression chamber and the needle piston 121" has no ring, but is slidably mounted in the second guide surface 132 "carried by the tubular body 11".
• the needle piston 121 projects into the hydraulic chamber 17 "and has at this level a circular groove 1210.
• a spring 21 is placed in the hydraulic chamber 17" surrounding the projecting portion of the needle piston 121 "and taking support on a shoulder of the tubular body 11 ".
• the other end of the spring 21 is held by a washer 22 stopped by a key 23 inserted into the circular groove 1210.
• the first guide surface 131 is also carried by the tubular body 11", the adapter piece being reduced to a support ring 13 "of the actuator 10 on another shoulder of the tubular body 11".
• a capillary 18 "connects the hydraulic chamber 17" to the supply duct 111 through the wall of the tubular body 11 ".
• the pressurized liquid in the supply conduit 111 passes through the capillary 18 "and fills the hydraulic chamber 17".
• the liquid also flows between the first guide surface 131 "and the actuator piston 101 towards the decompression chamber, then into the housing 16. The excess is discharged through the return line 15.
• the liquid under pressure acts on the one hand on the head 120 of the needle 12" exerting a force tending to move the head 120 of the seat 110, and secondly on the needle piston 121 “in the hydraulic chamber 17” exerting a force tending to take off the head 120 on the seat 110.
• the needle 12 " is further subjected to the elastic return force of the spring 21 which tends to press the head 120 onto the seat 110.
• the restoring force of the spring is chosen so that the head 120 is pressed onto the seat 110, whatever the pressure of the liquid in the feed duct 111 in the range of use of the device 1.
• the actuator 10 When it is desired to perform an injection, the actuator 10 is controlled so that the actuator piston 101 slides in the first guide surface 131 "It then controls the movement of the liquid contained in the hydraulic chamber 17".
• the liquid increases pressure so as to cause a force large enough to move the needle 12 and take off the head 120 of the seat 110. This increase in pressure is fast enough that the liquid does not have time to flow to through the capillary 18 "or along the actuator piston 101.
• the actuator 10 ' is an electrostrictive actuator, for example a piezoelectric actuator.
• the actuator 10 ' comprises a casing 100' of cylindrical shape and containing the active part of the actuator 10 '.
• the active part comprises a stack 102 'of piezoelectric material plates, fixed by its middle to the housing 100'. One end of the stack 102 'is free while the opposite end has the actuator piston 101'.
• the actuator 10 ' also comprises electrical supply means, not shown.
• the casing 100 ' is pressed against the adaptation piece 13' in the same manner as in the first embodiment. Other features are similar to those of the first embodiment, as well as the mode of operation.
• the bearing force of the actuator 10 is made by a spring.
• the variant of the first embodiment is also applicable to the second embodiment.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=41165652

Family Applications (1)

Country Status (3)

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Family Cites Families (9)

• 2009
  • 2009-02-02 FR FR0950639A patent/FR2941746A1/fr not_active Withdrawn
• 2010
  • 2010-01-27 EP EP10707599A patent/EP2391815A1/de not_active Withdrawn
  • 2010-01-27 WO PCT/FR2010/050126 patent/WO2010086553A1/fr not_active Ceased

Non-Patent Citations (1)

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