EP3139028A1 - Double ended coupler for servo actuator - Google Patents
Double ended coupler for servo actuator Download PDFInfo
- Publication number
- EP3139028A1 EP3139028A1 EP15183646.7A EP15183646A EP3139028A1 EP 3139028 A1 EP3139028 A1 EP 3139028A1 EP 15183646 A EP15183646 A EP 15183646A EP 3139028 A1 EP3139028 A1 EP 3139028A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- actuator
- actuator assembly
- reaction chamber
- plug
- fluid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000012530 fluid Substances 0.000 claims abstract description 38
- 239000000446 fuel Substances 0.000 claims abstract description 15
- 230000008602 contraction Effects 0.000 claims abstract description 6
- 229920002545 silicone oil Polymers 0.000 claims description 9
- 238000004891 communication Methods 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 description 30
- 238000000034 method Methods 0.000 description 6
- 238000005538 encapsulation Methods 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 230000033001 locomotion Effects 0.000 description 5
- 241000826860 Trapezium Species 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 125000006850 spacer group Chemical group 0.000 description 4
- 239000003292 glue Substances 0.000 description 3
- 239000003921 oil Substances 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000001154 acute effect Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000010339 dilation Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 239000004447 silicone coating Substances 0.000 description 1
- GOLXNESZZPUPJE-UHFFFAOYSA-N spiromesifen Chemical compound CC1=CC(C)=CC(C)=C1C(C(O1)=O)=C(OC(=O)CC(C)(C)C)C11CCCC1 GOLXNESZZPUPJE-UHFFFAOYSA-N 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
Images
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
Definitions
- the present invention relates to an actuator assembly for a fuel injector and more particularly to servo actuator provided with an integral hydraulic lash adjuster.
- injection events are indirectly commanded by energizing an actuator displacing a valve opening a spill orifice.
- an actuator displacing a valve opening a spill orifice.
- a spring displaces the valve closing said orifice.
- Servo actuators such as piezo or magneto-restrictive actuators, require hydraulic lash adjuster, hereafter HLA, also called “coupler” in order to adapt to slow variations of the lengths of the parts caused by temperature changes and wear.
- HLA hydraulic lash adjuster
- DE102010029106 , DE102009000203 , EP1519037 , WO2013053594 , WO2013053594 disclose examples of such injectors.
- the working volume of the HLA becomes pressurized when control valve is opened as the actuator is energized, but after an injection, inertia of the moving parts and the fluid leaked out during operation can cause cavities to form in the working fluid, meaning that motion of the parts is only well controlled in the compression direction.
- the actuator assembly has an elongated body provided with an internal bore extending from an opening to a bottom face and wherein a servo actuator member is arranged to extend and retract in order to cooperate with a valve member.
- the actuator assembly further comprises a hydraulic lash adjuster (hereafter HLA) filled with fluid, the HLA being provided with a first reaction chamber wherein pressure rises when the actuator member extends and wherein pressure drops when the actuator member retracts and, a second reaction chamber wherein pressure drops when the actuator member extends and wherein pressure rises when the actuator member retracts so that, the HLA is adapted to resist both the extensions and the contractions of the servo actuator member.
- HLA hydraulic lash adjuster
- first reaction chamber and the second reaction chamber are in fluid communication with each other.
- the first reaction chamber of the HLA is defined between a first inner shoulder face of the bore and a first outer shoulder face of the actuator member.
- the second reaction chamber of the HLA is defined between a second inner shoulder face of the bore and a second outer shoulder face of the actuator member.
- the actuator assembly may further comprise an annular reacting plug arranged in the bore and fixed to the actuator body.
- the plug locally restricts the section of the bore, the first inner shoulder face and the second inner shoulder face being integral to said annular plug.
- the actuator member has a thin head portion extending with clearance fit through a central opening of the annular plug and protruding in a secondary chamber defined between said second inner shoulder face and the bottom face of the bore.
- the actuator assembly may further comprise an annular collar engaged and fixed to the thin head portion protruding in a secondary chamber, the second outer shoulder face being integral to said collar.
- the annular collar may be threaded onto the head portion of the actuator member so that the volume of the second reaction chamber can be chosen by adjusting the axial position of the collar on the head portion.
- the actuator assembly may further comprise a locking screw adapted to lock the position of the annular collar over the head portion.
- the actuator assembly may further comprise a fluid absorbing member arranged in said secondary chamber, said fluid absorbing member being made of a material such as felt or sponge which by capillary action can attract the fluid ensuring that there is fluid present in the first reaction chamber and in the second reaction chamber irrespective of the orientation of the assembly.
- the actuator assembly may further comprise at least one securing member, such as a screw, securing the reacting plug to the actuator body.
- the fluid may be high viscosity silicone oil.
- the invention also extends to a fuel injector comprising an actuator assembly as described above.
- the actuator assembly 12 of a fuel injector 10 comprising an actuator body 14 extending along a longitudinal axis X1, drawn vertical on the figures the top-down arbitrary orientation of the figures being utilized to ease, simplify and clarify the present description without any intention to limit the invention.
- the actuator body 14 extends from an upper region 16, top of the figures, where can be placed an electrical connector not represented, to a lower transverse face 18 adapted to be in sealing surface contact against the top face of a control valve assembly not represented.
- the body 14 is also provided with an internal cylindrical cavity 20 extending inside the body 14 along a cavity axis X2 parallel to the longitudinal axis X1.
- the cavity 20 comprises a large bore 22 upwardly extending from an opening 24 in the lower transverse face 18, up to a bottom face 26 wherefrom a thinner conduit 28 upwardly extends toward the upper region 16.
- annular reacting plug 30 fixed to the body 14 the reacting plug 30 having a peripheral cylindrical face 32 that is in contact with the inner wall of the large bore, a first inner shoulder face 34, or lower face 34, a second inner shoulder face 36, or upper face 36 and, a central axial aperture 37 defining an inner cylindrical face.
- the cross section of the annular plug 30 is an isosceles trapezium, first 34 and second 36 shoulder faces being conical and symmetrical. The advantages attached to such embodiment are detailed below but alternatively, any other cross section would fit the purpose of the invention and in particular, acute or obtuse, symmetric or non-symmetric, trapezium sections.
- a reacting plug 30 having parallel plane upper and lower faces could also be chosen.
- the reacting plug 30 divides said large bore 22 into a main chamber 38, extending below the reacting plug 30 toward the opening 24 in the lower transverse face and, a secondary chamber 40 extending above the reacting plug 30 to the bottom face 26 of the large bore 22.
- the reacting plug 30 may be fixed in the large bore 22 by press-fit, as represented on figure 1 , or via securing members 42 such as pressing-screws 42, represented on figures 2 and 4 , said screws being radially threaded in the wall of the body 14, the sealing of the threaded holes being ensured after assembly with tightening glue or sealing paste.
- said bore 22 may be provided with a small pressing step 44 so that the section of the main chamber 38 below said step 44 is slightly enlarged facilitating the insertion of the plug 30.
- a servo actuator member 46 such as a piezo-electric or a magneto restrictive actuator, which has a large cylindrical actuation portion 48, a thinner head portion 50 and a first outer shoulder face 52 in-between them.
- the actuation portion 48 extends in the main chamber 38 from a lower face 54 to the first outer shoulder face 52 which faces the first inner shoulder face 34 of the reacting plug 30 then, the thinner head portion 50 upwardly extending from said first outer shoulder face 52 engages through the central opening 37 of the plug and protrudes on the opposite side in the secondary chamber 40.
- a male actuation pin 56 protrudes from the lower face 54 and, electrical wires departing from the thinner head portion 50 upwardly extend in the thinner conduit 28, toward the electrical connector.
- the collar 60 In the secondary chamber 40 is arranged with clearance fit a collar 60 that is fixed on the protruding portion of the head portion 50, the collar 60 having a lower face 62, or second outer shoulder face 62, arranged facing the second inner shoulder face 36 of the reacting plug, the two shoulder faces 36, 62, having complementary parallel profiles and, in the chosen illustrated example the lower face 62 is conical.
- the collar 60 has right-angled trapezium cross section, the lower face 62 being the sloped leg of the trapezium opposed to a transverse upper face 64 that is the right angle leg above which, in the secondary chamber 40, an actuator spring 66 compressed between said upper face 64 and the bottom face 26 of the large bore permanently downwardly solicits the actuator member 46.
- the collar 60 is provided on its upper face with a recess in which is arranged an absorbing member 68 made of a material such as felt or sponge.
- the absorbing member 68 is a thick washer above which a closing washer 70 closes the recess and receives the actuator spring 66, the axial force of the spring 66 being transmitted from the closing washer 70 to the collar 60 via an inner tubular spacer 72 through which is engaged the head portion 50.
- the spacer 72 can be integral to the collar 60, as represented on the figure, or can be provided separately as an independent component.
- a resilient sealing assembly 74 comprising a resilient sealing member 76 provided with a central aperture 78 through which extends the actuation pin 56, said sealing assembly 74 sealingly closing the cavity 20, thanks to an O-ring 80 arranged in the central aperture 78 and radially compressed between the sealing member 76 and the actuation pin 56.
- the actuator member 46 is arranged in the cavity 20 so that its lower face 54 remains inside the cavity 20 at a distance of the sealing member 76 defining between them a reservoir 82.
- the actuator member 46 is immersed in high viscosity fluid F such as silicone oil having typically a viscosity in the 1,000-800,000 centistokes range, said fluid F filling a fluid filling volume VF comprising all available spaces of the cavity 20, all said spaces being in fluid communication with each other.
- the fluid filling volume VF comprises the main chamber 38, the reservoir 82, the secondary chamber 40 wherein the fluid F is absorbed and captured in the absorbing washer 68 and also, the clearances for instance between the inner and outer shoulder faces.
- the fluid F may fill part of the secondary chamber, half for instance, so that said secondary chamber may act as a compensation reservoir ensuring that fluid is always present in the rest of the filling volume VF even if the actuator assembly is arranged in a slightly non vertical way, and also to allow for thermal expansion and contraction of the fluid.
- the actuation portion 48 of the actuator member comprises a piezo stack 84 axially compressed in a very stiff cage spring 86 having a tubular body provided with a plurality of regularly spaced transverse apertures 88 providing to the tubular body the required axial stiffness.
- the silicone oil F having a high dielectric strength of around 10-15kV/mm, and variants being compatible with silicone coatings often used to passivate the piezo stack, it is acceptable to have the oil F flowing through the transverse apertures 88 and to be in direct contact with the piezo stack 84 without generating dielectric breakdown.
- the clearance C is to be distinguished in several portions each varying in thickness.
- a large clearance C1 of few tens of microns is between first inner and first outer shoulder faces 34, 52, defining there between a first reaction chamber 90 and, similar large clearance C1 is also between the second inner and second outer shoulder faces 36, 62, defining there between a second reaction chamber 92.
- a small clearance C2 of few microns separates the head portion 50 of the actuator from the cylindrical wall of the central aperture 37 of the reacting plug.
- a similar small clearance C2 is also between the collar 60 and the wall of the secondary chamber 40.
- the first reacting chamber 90 and the second reacting chamber 92 are sloped in order to help evacuating toward the top of the injector any bubble of air that would be captured in the silicone oil F.
- the fuel injector 10 is connected to a control unit not represented which alternatively energizes or not the actuator member in order to command or to forbid injection events.
- the actuator member 46 When the actuator assembly 12 is energized, the actuator member 46 axially X2 expands so that the actuation pin 56 solicits and pushes a control valve that opens a spill orifice through which pressurized fuel gushes flowing toward an outlet consequently enabling fuel injection event. While the actuator 46 expands the pressure rises in the first reaction chamber 90 and drops in the second reaction chamber 92.
- the first reaction chamber 90 acts as a top mounted hydraulic lash adjuster (HLA) resisting and controlling the expansion motions of the actuator member 46.
- HLA top mounted hydraulic lash adjuster
- the actuator member 46 retracts to a rest length so the actuation pin 56 lifts off and the control valve closes the spill orifice, as being biased by a spring valve and consequently, fuel injection event is prevented. While the actuator 46 retracts it remains downwardly biased by the actuator spring 66 and, the pressure drops in the first reaction chamber 90 while it rises in the second reaction chamber 92.
- the second reaction chamber 92 acts as a top mounted hydraulic lash adjuster (HLA) resisting and controlling the contraction motions of the actuator 46.
- HLA top mounted hydraulic lash adjuster
- the actuator member 46 is able to accommodate with said dimensions variations.
- sealing assembly 74 It is important to isolate the silicone oil from exposure to fuel, one reason being that fuel has low viscosity and could affect the HLA performances.
- the sealing performance of the sealing assembly 74 is assured by the O-ring 80 compressed between the wall of the central aperture 78 of the sealing member 76 and the actuation pin 56.
- a metal diaphragm or bellows welded to the actuator body 14 and also to the actuation pin 56 could be used, such embodiments being described in application GB1512350 filed 15 July 2015 .
- a separate filling orifice would be added and would typically be plugged with a metal ball, or a plug, after filling the oil the filling orifice extending in the wall of the actuator body from an opening in the lower transverse face of the body, or alternatively in the outer peripheral face, to another opening inside the cavity.
- the actuation portion 56 is further provided with a metal encapsulation tube 94 enclosing the cage spring 86 and the piezo stack 84.
- Said encapsulation tube 94 protects the stack 84 from direct fluid contact and consequent dielectric breakdown. This may occur either if the fluid F has intrinsically a low dielectric strength or, if the sealing performance of the sealing assembly 74 is not sufficient enabling minor fuel leaks inside the cavity.
- a small clearance similar to the previously described small clearance C1, is reserved between the tubular encapsulation 94 and the cylindrical wall of the main chamber 38 of the large bore 22.
- the fluid filling volume VF comprises the reservoir 82, said small clearance C1 surrounding the encapsulation tube 94, the first reaction chamber 90 and the second reaction chamber 92 and, the secondary chamber 40 wherein the fluid F is absorbed and captured in the absorbing member 68.
- the assembly process 110 of this first embodiment depends upon the fixation means of the plug 30 in the body 14.
- a second embodiment now described in reference to figures 3 and 4 , enables tuning of the resisting force and controlling motion of the actuator member 46 due to its contractions when not energized. Said adjustment is provided with adjusting means for trimming the large clearance C1 of the second reacting chamber 92.
- the collar 60 is no longer permanently fixed on the head portion 50.
- the central bore of the collar and the head portion 50 are complementary threaded and so, the collar 60 is screwed onto the head portion 50 to a position where the lower face 62 of the collar is precisely at a desired distance from the upper face 36 of the restricting plug.
- the collar's position is locked thanks to a locking screw 96 provided with an external thread so that, as visible of the figure, it is engaged and screwed in the central aperture of the collar 60 to the point where said locking screw 96 comes in abutment against the head portion 50 of the actuator member, where it is tightened locking the collar 60 in a fixed position.
- the locking screw 96 is provided with an axial drive feature such as a slot and, the collar 60 with a radial drive feature such as a hexagon socket, a compact tool 98 can be made which can access both features whilst having room for a bore to pass the actuator electrical connections through.
- This adjusting means enables to set the collar 60 in an operating assembly and therefore to trim it to provide the same performances of a particular parameter for a given electrical drive signal.
- this parameter could for example be opening delay, or fuelling.
- This second embodiment might be easier to assemble should the annular reacting plug 30 be fixed to the body 14 by securing members 42 as shown on figure 4 .
- the assembly process 110 of this second embodiment comprises the following steps:
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
Description
- The present invention relates to an actuator assembly for a fuel injector and more particularly to servo actuator provided with an integral hydraulic lash adjuster.
- In fuel injectors, injection events are indirectly commanded by energizing an actuator displacing a valve opening a spill orifice. When the actuator is no longer energized, a spring displaces the valve closing said orifice.
- Servo actuators, such as piezo or magneto-restrictive actuators, require hydraulic lash adjuster, hereafter HLA, also called "coupler" in order to adapt to slow variations of the lengths of the parts caused by temperature changes and wear.
DE102010029106 ,DE102009000203 ,EP1519037 ,WO2013053594 ,WO2013053594 disclose examples of such injectors. - The working volume of the HLA becomes pressurized when control valve is opened as the actuator is energized, but after an injection, inertia of the moving parts and the fluid leaked out during operation can cause cavities to form in the working fluid, meaning that motion of the parts is only well controlled in the compression direction.
- Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing an actuator assembly of a fuel injector. The actuator assembly has an elongated body provided with an internal bore extending from an opening to a bottom face and wherein a servo actuator member is arranged to extend and retract in order to cooperate with a valve member.
- The actuator assembly further comprises a hydraulic lash adjuster (hereafter HLA) filled with fluid, the HLA being provided with a first reaction chamber wherein pressure rises when the actuator member extends and wherein pressure drops when the actuator member retracts and, a second reaction chamber wherein pressure drops when the actuator member extends and wherein pressure rises when the actuator member retracts so that, the HLA is adapted to resist both the extensions and the contractions of the servo actuator member.
- Also, the first reaction chamber and the second reaction chamber are in fluid communication with each other.
- In an embodiment, the first reaction chamber of the HLA is defined between a first inner shoulder face of the bore and a first outer shoulder face of the actuator member.
- Also, the second reaction chamber of the HLA is defined between a second inner shoulder face of the bore and a second outer shoulder face of the actuator member.
- The actuator assembly may further comprise an annular reacting plug arranged in the bore and fixed to the actuator body. The plug locally restricts the section of the bore, the first inner shoulder face and the second inner shoulder face being integral to said annular plug.
- Also, the actuator member has a thin head portion extending with clearance fit through a central opening of the annular plug and protruding in a secondary chamber defined between said second inner shoulder face and the bottom face of the bore.
- The actuator assembly may further comprise an annular collar engaged and fixed to the thin head portion protruding in a secondary chamber, the second outer shoulder face being integral to said collar.
- The annular collar may be threaded onto the head portion of the actuator member so that the volume of the second reaction chamber can be chosen by adjusting the axial position of the collar on the head portion.
- Also, the actuator assembly may further comprise a locking screw adapted to lock the position of the annular collar over the head portion.
- Also, the actuator assembly may further comprise a fluid absorbing member arranged in said secondary chamber, said fluid absorbing member being made of a material such as felt or sponge which by capillary action can attract the fluid ensuring that there is fluid present in the first reaction chamber and in the second reaction chamber irrespective of the orientation of the assembly.
- Also, the actuator assembly may further comprise at least one securing member, such as a screw, securing the reacting plug to the actuator body.
- The fluid may be high viscosity silicone oil.
- The invention also extends to a fuel injector comprising an actuator assembly as described above.
- The present invention is now described by way of example with reference to the accompanying drawings in which:
-
Figure 1 is an axial section of a first embodiment of an actuator assembly comprising an integral hydraulic lash adjuster as per the invention. -
Figure 2 is an axial section of a, alternative embodiment of an actuator assembly as per the invention. -
Figure 3 is an axial section of a second embodiment of an actuator assembly as per the invention. -
Figure 4 is an external view of the actuator assembly offigure 3 . - In reference to the figures is described the
actuator assembly 12 of afuel injector 10, theassembly 12 comprising anactuator body 14 extending along a longitudinal axis X1, drawn vertical on the figures the top-down arbitrary orientation of the figures being utilized to ease, simplify and clarify the present description without any intention to limit the invention. Theactuator body 14 extends from anupper region 16, top of the figures, where can be placed an electrical connector not represented, to a lowertransverse face 18 adapted to be in sealing surface contact against the top face of a control valve assembly not represented. Thebody 14 is also provided with an internalcylindrical cavity 20 extending inside thebody 14 along a cavity axis X2 parallel to the longitudinal axis X1. Thecavity 20 comprises alarge bore 22 upwardly extending from an opening 24 in the lowertransverse face 18, up to abottom face 26 wherefrom athinner conduit 28 upwardly extends toward theupper region 16. - In the
large bore 22 is arranged anannular reacting plug 30 fixed to thebody 14 the reactingplug 30 having a peripheralcylindrical face 32 that is in contact with the inner wall of the large bore, a firstinner shoulder face 34, orlower face 34, a secondinner shoulder face 36, orupper face 36 and, a centralaxial aperture 37 defining an inner cylindrical face. On the illustrated example of the figures the cross section of theannular plug 30 is an isosceles trapezium, first 34 and second 36 shoulder faces being conical and symmetrical. The advantages attached to such embodiment are detailed below but alternatively, any other cross section would fit the purpose of the invention and in particular, acute or obtuse, symmetric or non-symmetric, trapezium sections. A reactingplug 30 having parallel plane upper and lower faces could also be chosen. - In place in the
large bore 22, the reactingplug 30 divides saidlarge bore 22 into amain chamber 38, extending below the reactingplug 30 toward the opening 24 in the lower transverse face and, asecondary chamber 40 extending above the reactingplug 30 to thebottom face 26 of thelarge bore 22. - The reacting
plug 30 may be fixed in thelarge bore 22 by press-fit, as represented onfigure 1 , or via securingmembers 42 such as pressing-screws 42, represented onfigures 2 and4 , said screws being radially threaded in the wall of thebody 14, the sealing of the threaded holes being ensured after assembly with tightening glue or sealing paste. In the particular press-fit arrangement, to minimize the pressing distance of theplug 30 into thelarge bore 22, saidbore 22 may be provided with a smallpressing step 44 so that the section of themain chamber 38 below saidstep 44 is slightly enlarged facilitating the insertion of theplug 30. - In the
cavity 20 is arranged with clearance fit C aservo actuator member 46, such as a piezo-electric or a magneto restrictive actuator, which has a largecylindrical actuation portion 48, athinner head portion 50 and a firstouter shoulder face 52 in-between them. Theactuation portion 48 extends in themain chamber 38 from alower face 54 to the firstouter shoulder face 52 which faces the firstinner shoulder face 34 of the reactingplug 30 then, thethinner head portion 50 upwardly extending from said firstouter shoulder face 52 engages through thecentral opening 37 of the plug and protrudes on the opposite side in thesecondary chamber 40. Amale actuation pin 56 protrudes from thelower face 54 and, electrical wires departing from thethinner head portion 50 upwardly extend in thethinner conduit 28, toward the electrical connector. - In the
secondary chamber 40 is arranged with clearance fit acollar 60 that is fixed on the protruding portion of thehead portion 50, thecollar 60 having alower face 62, or secondouter shoulder face 62, arranged facing the secondinner shoulder face 36 of the reacting plug, the twoshoulder faces lower face 62 is conical. - In a non-represented embodiment, the
collar 60 has right-angled trapezium cross section, thelower face 62 being the sloped leg of the trapezium opposed to a transverseupper face 64 that is the right angle leg above which, in thesecondary chamber 40, anactuator spring 66 compressed between saidupper face 64 and thebottom face 26 of the large bore permanently downwardly solicits theactuator member 46. - Otherwise, in the represented embodiments the
collar 60 is provided on its upper face with a recess in which is arranged anabsorbing member 68 made of a material such as felt or sponge. On the figures, the absorbingmember 68 is a thick washer above which a closing washer 70 closes the recess and receives theactuator spring 66, the axial force of thespring 66 being transmitted from theclosing washer 70 to thecollar 60 via an innertubular spacer 72 through which is engaged thehead portion 50. Thespacer 72 can be integral to thecollar 60, as represented on the figure, or can be provided separately as an independent component. - At the opposite extremity of the large bore, the opening 24 in the lower
transverse face 18 is closed by aresilient sealing assembly 74 comprising aresilient sealing member 76 provided with acentral aperture 78 through which extends theactuation pin 56, saidsealing assembly 74 sealingly closing thecavity 20, thanks to an O-ring 80 arranged in thecentral aperture 78 and radially compressed between the sealingmember 76 and theactuation pin 56. - The
actuator member 46 is arranged in thecavity 20 so that itslower face 54 remains inside thecavity 20 at a distance of the sealingmember 76 defining between them areservoir 82. - Inside the
cavity 20, theactuator member 46 is immersed in high viscosity fluid F such as silicone oil having typically a viscosity in the 1,000-800,000 centistokes range, said fluid F filling a fluid filling volume VF comprising all available spaces of thecavity 20, all said spaces being in fluid communication with each other. The fluid filling volume VF comprises themain chamber 38, thereservoir 82, thesecondary chamber 40 wherein the fluid F is absorbed and captured in the absorbingwasher 68 and also, the clearances for instance between the inner and outer shoulder faces. In the non-represented embodiment where no absorbing member is arranged in thesecondary chamber 40, the fluid F may fill part of the secondary chamber, half for instance, so that said secondary chamber may act as a compensation reservoir ensuring that fluid is always present in the rest of the filling volume VF even if the actuator assembly is arranged in a slightly non vertical way, and also to allow for thermal expansion and contraction of the fluid. - In a first embodiment depicted on
figure 1 , theactuation portion 48 of the actuator member comprises apiezo stack 84 axially compressed in a verystiff cage spring 86 having a tubular body provided with a plurality of regularly spacedtransverse apertures 88 providing to the tubular body the required axial stiffness. Also, the silicone oil F having a high dielectric strength of around 10-15kV/mm, and variants being compatible with silicone coatings often used to passivate the piezo stack, it is acceptable to have the oil F flowing through thetransverse apertures 88 and to be in direct contact with thepiezo stack 84 without generating dielectric breakdown. - In said first embodiment, the clearance C is to be distinguished in several portions each varying in thickness. For example, a large clearance C1 of few tens of microns is between first inner and first outer shoulder faces 34, 52, defining there between a first reaction chamber 90 and, similar large clearance C1 is also between the second inner and second
outer shoulder faces head portion 50 of the actuator from the cylindrical wall of thecentral aperture 37 of the reacting plug. A similar small clearance C2 is also between thecollar 60 and the wall of thesecondary chamber 40. - The above values actually depend on the characteristics chosen oil and are here given as illustrating examples. Considering the large range of viscosity of silicone oils, a specific clearance can vary by a factor ten or even hundred.
- In a preferred arrangement represented on the figure, the first reacting chamber 90 and the second reacting chamber 92 are sloped in order to help evacuating toward the top of the injector any bubble of air that would be captured in the silicone oil F.
- In operation, the
fuel injector 10 is connected to a control unit not represented which alternatively energizes or not the actuator member in order to command or to forbid injection events. - When the
actuator assembly 12 is energized, theactuator member 46 axially X2 expands so that theactuation pin 56 solicits and pushes a control valve that opens a spill orifice through which pressurized fuel gushes flowing toward an outlet consequently enabling fuel injection event. While theactuator 46 expands the pressure rises in the first reaction chamber 90 and drops in the second reaction chamber 92. The first reaction chamber 90 acts as a top mounted hydraulic lash adjuster (HLA) resisting and controlling the expansion motions of theactuator member 46. - To the contrary, when the
actuator assembly 12 is not energized, theactuator member 46 retracts to a rest length so theactuation pin 56 lifts off and the control valve closes the spill orifice, as being biased by a spring valve and consequently, fuel injection event is prevented. While theactuator 46 retracts it remains downwardly biased by theactuator spring 66 and, the pressure drops in the first reaction chamber 90 while it rises in the second reaction chamber 92. The second reaction chamber 92 acts as a top mounted hydraulic lash adjuster (HLA) resisting and controlling the contraction motions of theactuator 46. - Also, in time the dimensions of the
actuator assembly 12 slightly vary for instance due to wear or heat dilation of the parts. Thanks to the HLA provided by clearances C and occupied by the fluid F, theactuator member 46 is able to accommodate with said dimensions variations. - It is important to isolate the silicone oil from exposure to fuel, one reason being that fuel has low viscosity and could affect the HLA performances. The sealing performance of the sealing
assembly 74 is assured by the O-ring 80 compressed between the wall of thecentral aperture 78 of the sealingmember 76 and theactuation pin 56. Several alternative embodiments of the sealingassembly 74, as well as methods of assembly and operations are detailed in applicationGB1511355 filed 29 June 2015 - Instead of the sealing
assembly 74 previously described, a metal diaphragm or bellows welded to theactuator body 14 and also to theactuation pin 56 could be used, such embodiments being described in applicationGB1512350 filed 15 July 2015 - In an alternative embodiment represented on
figure 2 , theactuation portion 56 is further provided with ametal encapsulation tube 94 enclosing thecage spring 86 and thepiezo stack 84. Saidencapsulation tube 94 protects thestack 84 from direct fluid contact and consequent dielectric breakdown. This may occur either if the fluid F has intrinsically a low dielectric strength or, if the sealing performance of the sealingassembly 74 is not sufficient enabling minor fuel leaks inside the cavity. In this alternative embodiment a small clearance, similar to the previously described small clearance C1, is reserved between thetubular encapsulation 94 and the cylindrical wall of themain chamber 38 of thelarge bore 22. The fluid filling volume VF comprises thereservoir 82, said small clearance C1 surrounding theencapsulation tube 94, the first reaction chamber 90 and the second reaction chamber 92 and, thesecondary chamber 40 wherein the fluid F is absorbed and captured in the absorbingmember 68. - The assembly process 110 of this first embodiment depends upon the fixation means of the
plug 30 in thebody 14. - In the case the reacting
plug 30 is fixed by press-fit,figure 1 , the procedure follows the following steps: - providing 112 an equipped actuator member by:
- engaging 114 the reacting
plug 30 over thehead portion 50; - press fitting 116 the
collar 60 in position over thehead portion 50; - arranging 118 in place the absorbing
member 68, thespacer 72 and the closingwasher 70 if required and, theactuator spring 66;
- engaging 114 the reacting
- engaging 120 said equipped actuator member in the
cavity 20 by inserting it via theopening 24 and adjusting the position by forcing the reactingplug 30 to be press-fit inside thebore 24; - arranging 122 the sealing
member 76 in theopening 24 of the large bore; - filling 124 with the fluid filling volume VF with fluid F;
- sealing 126 the assembly by arranging the O-
ring 80 in position in the sealingmember 76 and around theactuation pin 56. - In the case the reacting
plug 30 is fixed to the body with securingmembers 42,figure 2 , the procedure varies by the engaging step 120 that becomes: - engaging 120 the equipped actuator member in the
cavity 20 by inserting it via thelarge bore opening 24, adjusting the position so the reactingplug 30 is in the desired position, locking the securingmember 42 so that theplug 30 is fixed to thebody 14 and, - sealing 121 the securing
member 42 for instance with glue applied on the threads or with sealing paste. - A second embodiment, now described in reference to
figures 3 and 4 , enables tuning of the resisting force and controlling motion of theactuator member 46 due to its contractions when not energized. Said adjustment is provided with adjusting means for trimming the large clearance C1 of the second reacting chamber 92. - In this second embodiment the
collar 60 is no longer permanently fixed on thehead portion 50. The central bore of the collar and thehead portion 50 are complementary threaded and so, thecollar 60 is screwed onto thehead portion 50 to a position where thelower face 62 of the collar is precisely at a desired distance from theupper face 36 of the restricting plug. Once said precise distance adjusted, the collar's position is locked thanks to a lockingscrew 96 provided with an external thread so that, as visible of the figure, it is engaged and screwed in the central aperture of thecollar 60 to the point where said lockingscrew 96 comes in abutment against thehead portion 50 of the actuator member, where it is tightened locking thecollar 60 in a fixed position. - To enable to firmly lock the
collar 60 in position, the lockingscrew 96 is provided with an axial drive feature such as a slot and, thecollar 60 with a radial drive feature such as a hexagon socket, acompact tool 98 can be made which can access both features whilst having room for a bore to pass the actuator electrical connections through. - This adjusting means enables to set the
collar 60 in an operating assembly and therefore to trim it to provide the same performances of a particular parameter for a given electrical drive signal. In an injector, this parameter could for example be opening delay, or fuelling. - This second embodiment might be easier to assemble should the annular reacting
plug 30 be fixed to thebody 14 by securingmembers 42 as shown onfigure 4 . - The assembly process 110 of this second embodiment comprises the following steps:
- providing 112 an equipped actuator member by:
- engaging 114 the reacting
plug 30 over thehead portion 50, - screwing 128 the
collar 60 in position over thehead portion 50, - screwing 130 the locking
screw 96 and locking thecollar 60 in a preset position, - arranging 118 in place the absorbing
washer 68 and theactuator spring 66 and, eventually if required, the closingwasher 70;
- engaging 114 the reacting
- engaging 120 said equipped actuator member in the
cavity 20 by inserting it via thelarge bore opening 24; - fixing 132 the reacting
plug 30 in position by tightening the securingmembers 42; - sealing 121 the securing
member 42 for instance with glue applied on the threads or with sealing paste. - arranging 122 the sealing
member 76 in theopening 24 of the large bore; - filling 124 the fluid filling volume VF with fluid F;
- sealing 126 the assembly by arranging the O-
ring 80 in position in the sealingmember 76 and around theactuation pin 56; - tuning 134 the resisting motion of the
actuator member 46 by inserting thetool 98 in thebody 14 and adjusting the position of thecollar 60. -
- X1
- longitudinal axis
- X2
- cavity axis
- C
- clearance
- F
- fluid - silicone oil
- VF
- fluid filling volume
- C1
- large clearance
- C2
- small clearance
- HLA
- hydraulic lash adjuster
- 10
- injector
- 12
- actuator assembly
- 14
- actuator body
- 16
- upper region of the body
- 18
- lower transverse face of the body
- 20
- cavity
- 22
- large bore
- 24
- opening of the large bore in the lower transverse face
- 26
- bottom face of the large bore
- 28
- thinner conduit
- 30
- annular reacting plug
- 32
- peripheral cylindrical face of the reacting plug
- 34
- first inner shoulder face - lower face of the reacting plug
- 36
- second inner shoulder face - upper face of the reacting plug
- 37
- central opening of the reacting plug
- 38
- main chamber
- 40
- secondary chamber
- 42
- securing member
- 44
- pressing step
- 46
- actuator member
- 48
- large actuation portion
- 50
- thinner head portion
- 52
- first outer shoulder face of the actuator member
- 54
- lower face of the actuator member
- 56
- actuation pin
- 37
- central opening of the reacting plug
- 60
- collar
- 62
- lower face of the collar - second outer shoulder face
- 64
- upper face of the collar
- 66
- actuator spring
- 68
- absorbing member - washer
- 70
- closing washer
- 72
- spacer
- 74
- sealing assembly
- 76
- sealing member
- 78
- central aperture
- 80
- O-ring
- 82
- reservoir
- 84
- piezo stack
- 86
- cage spring
- 88
- transverse apertures
- 90
- first reaction chamber
- 92
- second reaction chamber
- 94
- metal encapsulation
- 96
- locking screw
- 98
- tool
- 110
- assembly process
- 112
- step: providing equipped actuator assembly
- 114
- step: engaging the reacting plug
- 116
- step: press fit the collar
- 118
- step: arranging absorbing washer, spring...
- 120
- step: engaging the equipped actuator in the cavity
- 121
- step: sealing securing members
- 122
- step: arranging the sealing member
- 124
- step: filling the fluid
- 126
- step: sealing with the O-ring
- 128
- step: screwing the collar
- 130
- step: screwing the locking screw
- 132
- step: fixing the reacting plug
- 134
- step: tuning
Claims (13)
- Actuator assembly (12) of a fuel injector (10), the actuator assembly (12) having an elongated body (14) provided with an internal bore (22) extending from an opening (24) to a bottom face (26) and wherein a servo actuator member (46) is arranged to extend and retract in order to cooperate with a valve member, characterized in that
the actuator assembly (12) further comprises a hydraulic lash adjuster (HLA) filled with fluid (F), the HLA being provided with a first reaction chamber (90) wherein pressure rises when the actuator member (46) extends and wherein pressure drops when the actuator member (46) retracts and, also with a second reaction chamber (92) wherein pressure drops when the actuator member (46) extends and wherein pressure rises when the actuator member (46) retracts so that, the HLA is adapted to resist both the extensions and the contractions of the servo actuator member (46). - Actuator assembly (12) as claimed in the preceding claim wherein the first reaction chamber (90) and the second reaction chamber (92) are in fluid communication with each other.
- Actuator assembly (12) as claimed in any one of the preceding claims wherein the first reaction chamber (90) of the HLA is defined between a first inner shoulder face (34) of the bore (22) and a first outer shoulder face (52) of the actuator member (46).
- Actuator assembly (12) as claimed in claim 3 wherein the second reaction chamber (92) of the HLA is defined between a second inner shoulder face (36) of the bore (22) and a second outer shoulder face (62) of the actuator member (46).
- Actuator assembly (12) as claimed in claim 4 further comprising an annular reacting plug (30) arranged in the bore (22) and fixed to the actuator body (14), said plug (30) locally restricting the section of the bore (22), the first inner shoulder face (34) and the second inner shoulder face (36) being integral to said annular plug (30).
- Actuator assembly (12) as claimed in claim 5 wherein the actuator member (46) has a thin head portion (50) extending with clearance fit through a central opening (37) of the annular plug (30) and protruding in a secondary chamber (40) defined between said second inner shoulder face (36) and the bottom face (26) of the bore (22).
- Actuator assembly (12) as claimed in claim 6 wherein, the actuator assembly (12) further comprises an annular collar (60) engaged and fixed to the thin head portion (50) protruding in a secondary chamber (40), the second outer shoulder face (62) being integral to said collar (60).
- Actuator assembly (12) as claimed claim 7 wherein the annular collar (60) is threaded onto the head portion (50) of the actuator member (46) so that the volume of the second reaction chamber (92) can be chosen by adjusting the axial position of the collar (60) on the head portion (50).
- Actuator assembly (12) as claimed in claim 8 further comprising a locking screw (96) adapted to lock the position of the annular collar (60) over the head portion (50).
- Actuator assembly (12) as claimed in any one of the claims 6 to 9 further comprising a fluid absorbing member (68) arranged in said secondary chamber (40), said fluid absorbing member (68) being made of a material such as felt or sponge which by capillary action can attract the fluid (F) ensuring that there is fluid present in the first reaction chamber (90) and in the second reaction chamber (92) irrespective of the orientation of the assembly (12).
- Actuator assembly (12) as claimed in any one of the claims 5 to 10 further comprising at least one securing member (42), such as a screw, securing the reacting plug (30) to the actuator body (14).
- Actuator assembly (12) as claimed in any one of the preceding claims wherein the fluid (F) is high viscosity silicone oil.
- Fuel injector (10) comprising an actuator assembly (12) as claimed in any of the preceding claims.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP15183646.7A EP3139028A1 (en) | 2015-09-03 | 2015-09-03 | Double ended coupler for servo actuator |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP15183646.7A EP3139028A1 (en) | 2015-09-03 | 2015-09-03 | Double ended coupler for servo actuator |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3139028A1 true EP3139028A1 (en) | 2017-03-08 |
Family
ID=54062649
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP15183646.7A Withdrawn EP3139028A1 (en) | 2015-09-03 | 2015-09-03 | Double ended coupler for servo actuator |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP3139028A1 (en) |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10039543A1 (en) * | 2000-08-12 | 2002-02-28 | Daimler Chrysler Ag | Injection valve for internal combustion engine has back pressure valves that connect lower pressure ranges adjacent to valve play adjustment to pressure chambers |
WO2005026532A1 (en) * | 2003-09-12 | 2005-03-24 | Siemens Aktiengesellschaft | Metering device |
EP1519037A1 (en) | 2003-09-29 | 2005-03-30 | Robert Bosch Gmbh | Fuel injection valve |
EP1591656A2 (en) * | 2004-04-26 | 2005-11-02 | Isuzu Motors Limited | Differential expansion absorption mechanism and fuel injection valve comprising same |
DE102005045893A1 (en) * | 2005-09-26 | 2007-04-05 | Siemens Ag | Hydraulic compensation unit for compensating for linear differences e.g. for piezo actuators of fuel injectors comprises an outer plate fixed within a housing to delimit hydraulic chambers with inner plates guided within the housing |
DE102009000203A1 (en) | 2009-01-14 | 2010-07-15 | Robert Bosch Gmbh | Hydraulic module for fuel injector, has valve plate with bore, control valve arranged in or on valve plate, valve stem with valve-side end and actuator side end |
DE102010029106A1 (en) | 2010-05-19 | 2011-11-24 | Robert Bosch Gmbh | Fuel injector, has coupler body whose rigidity is determined such that gap between coupler body and single-row trained biasing spring is increased by locally diameter enlargement of coupler body |
WO2013053594A1 (en) | 2011-10-14 | 2013-04-18 | Robert Bosch Gmbh | Hydraulic coupling |
-
2015
- 2015-09-03 EP EP15183646.7A patent/EP3139028A1/en not_active Withdrawn
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10039543A1 (en) * | 2000-08-12 | 2002-02-28 | Daimler Chrysler Ag | Injection valve for internal combustion engine has back pressure valves that connect lower pressure ranges adjacent to valve play adjustment to pressure chambers |
WO2005026532A1 (en) * | 2003-09-12 | 2005-03-24 | Siemens Aktiengesellschaft | Metering device |
EP1519037A1 (en) | 2003-09-29 | 2005-03-30 | Robert Bosch Gmbh | Fuel injection valve |
EP1591656A2 (en) * | 2004-04-26 | 2005-11-02 | Isuzu Motors Limited | Differential expansion absorption mechanism and fuel injection valve comprising same |
DE102005045893A1 (en) * | 2005-09-26 | 2007-04-05 | Siemens Ag | Hydraulic compensation unit for compensating for linear differences e.g. for piezo actuators of fuel injectors comprises an outer plate fixed within a housing to delimit hydraulic chambers with inner plates guided within the housing |
DE102009000203A1 (en) | 2009-01-14 | 2010-07-15 | Robert Bosch Gmbh | Hydraulic module for fuel injector, has valve plate with bore, control valve arranged in or on valve plate, valve stem with valve-side end and actuator side end |
DE102010029106A1 (en) | 2010-05-19 | 2011-11-24 | Robert Bosch Gmbh | Fuel injector, has coupler body whose rigidity is determined such that gap between coupler body and single-row trained biasing spring is increased by locally diameter enlargement of coupler body |
WO2013053594A1 (en) | 2011-10-14 | 2013-04-18 | Robert Bosch Gmbh | Hydraulic coupling |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7886993B2 (en) | Injection valve | |
US9086041B2 (en) | Fuel injector having a piezoelectric actuator and a sensor assembly | |
US7309032B2 (en) | Dosing device for fluids, especially a motor vehicle injection valve | |
US20080265716A1 (en) | Piezoelectric actuator with a sheath, for disposition in a piezoelectric injector | |
JP4606605B2 (en) | Fuel injection valve for internal combustion engine | |
US8479711B2 (en) | Piezoelectric direct acting fuel injector with hydraulic link | |
KR100933626B1 (en) | Fuel injection valve | |
DE102009026532A1 (en) | Fluid e.g. oil, injection valve for internal combustion engine, has piston and housing connected by diaphragm, which limits balancing area connected with gap and running over channel in piston and containing throttle point | |
US20020179062A1 (en) | Hydraulic compensator for a piezoelectrical fuel injector | |
WO2007002787A1 (en) | Fuel injector with piezoelectric actuator preload | |
KR20000015898A (en) | Fuel injection valve with a piezo-electric or magnetostrictive actuator | |
US6520423B1 (en) | Hydraulic intensifier assembly for a piezoelectric actuated fuel injector | |
JP2009108982A (en) | Hydraulic shock absorber and its assembling method | |
JP4297879B2 (en) | Injector | |
KR20010101060A (en) | Valve for controlling liquids | |
US6260541B1 (en) | Hydraulic lash adjuster | |
KR102220594B1 (en) | Fuel injector assembly | |
EP3118443A1 (en) | Servo actuator for fuel injector | |
EP3139028A1 (en) | Double ended coupler for servo actuator | |
US8998115B2 (en) | Injection valve comprising a transmission unit | |
CN102472210B (en) | Valve arrangement | |
JP2019116940A (en) | Damper | |
US20050139273A1 (en) | Electromechanically controlled proportional valve | |
JP2004197743A (en) | Fuel injection valve | |
EP3274583B1 (en) | Control valve arrangement |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
AX | Request for extension of the european patent |
Extension state: BA ME |
|
17P | Request for examination filed |
Effective date: 20170908 |
|
RBV | Designated contracting states (corrected) |
Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 20190402 |