EP1391608A1 - Doseur avec unité de compensation thermique - Google Patents

Doseur avec unité de compensation thermique Download PDF

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Publication number
EP1391608A1
EP1391608A1 EP02018666A EP02018666A EP1391608A1 EP 1391608 A1 EP1391608 A1 EP 1391608A1 EP 02018666 A EP02018666 A EP 02018666A EP 02018666 A EP02018666 A EP 02018666A EP 1391608 A1 EP1391608 A1 EP 1391608A1
Authority
EP
European Patent Office
Prior art keywords
piston
housing
piezoelectric actuator
fluid chamber
metering device
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.)
Granted
Application number
EP02018666A
Other languages
German (de)
English (en)
Other versions
EP1391608B1 (fr
Inventor
Fabrizio Biagetti
Marco Pulejo
Marco Siringo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zendra Systems SpA
Original Assignee
Siemens VDO Automotive SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens VDO Automotive SpA filed Critical Siemens VDO Automotive SpA
Priority to DE2002604565 priority Critical patent/DE60204565T2/de
Priority to EP20020018666 priority patent/EP1391608B1/fr
Publication of EP1391608A1 publication Critical patent/EP1391608A1/fr
Application granted granted Critical
Publication of EP1391608B1 publication Critical patent/EP1391608B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • 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
    • 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

Definitions

  • the present invention relates to a metering device for dosing pressurized fluids, particularly an injection valve for a fuel injection system in an internal combustion engine.
  • the metering device is of the type which comprises a housing having a metering opening, controllable by the movement of an axially moveable valve needle, the housing comprising a material having a first thermal coefficient of expansion, an axially extendable piezoelectric actuator cooperating with the valve needle to control its axial movement, the piezoelectric actuator comprising a material having a second thermal coefficient of expansion, and a thermal compensator unit cooperating with the piezoelectric actuator and the housing to compensate for different thermal expansion of the housing and the piezoelectric actuator to ensure elastic contact between an end stop of the housing, the piezoelectric actuator and the valve needle.
  • the piezoelectric actuator having a lower coefficient of thermal expansion than the outer housing, would not maintain Hertzian contact between its fixed end stop surface and the top end of the valve needle.
  • the injector valve is typically equipped with a hydraulic thermal compensation unit.
  • the thermal compensation unit recovers the clearance that would otherwise be created between the valve needle and the piezoelectric actuator, thereby avoiding incorrect and potentially hazardous operation conditions.
  • current designs have the disadvantages that an excessive number of pieces is required, that the manufacturing costs are high and that some of the parts, such as the bellows are critical.
  • the means for transmitting the axial extension of the piezoelectric actuator may, for example, be formed by a separate element disposed between the piezoelectric actuator and the compensator housing or the piston, or simply by a common contact surface of those elements.
  • the thermal compensator unit further comprises restoring means to return the hydraulic piston to its initial position and to return the hydraulic fluid from the second fluid chamber (38) to the first fluid chamber (36) in a deactivation phase of the piezoelectric actuator (28).
  • a return passage for the hydraulic fluid between the second and first fluid chamber is provided inside the hydraulic piston for rapidly returning the hydraulic fluid in a deactivation phase of the piezoelectric actuator.
  • the return passage through the piston may, in an advantageous embodiment of the metering device, have an opening in the first fluid chamber, the opening being covered by a spot-welded metal strip which is pressed on the opening in the activation phase and which bends away form the opening in the deactivation phase due to the pressure exerted by the hydraulic fluid, to rapidly return the hydraulic fluid to the first fluid chamber.
  • an upper surface of the compensator housing is connected to the end stop of the housing, and a lower surface of the hydraulic piston is connected to the piezoelectric actuator.
  • the restoring means may advantageously comprise a helical spring acting on the hydraulic piston via an end stop plate connected to an end portion of the hydraulic piston, the helical spring being precompressed during the assembly process, the oil being pressurized and the piston applying a pre-load contact force to the piezoelectric actuator and the valve needle, at any operating condition.
  • the helical spring is further compressed by an axial extension of the piezoelectric actuator.
  • the restoring means may comprise a Belleville washer, a compact type of spring in the shape of a washer pressed into a dished shape, arranged between the hydraulic piston and the upper surface of the compensator housing, the Belleville washer being compressed by an axial extension of the piezoelectric actuator.
  • the hydraulic piston may have an upper part sliding within the compensator housing and a lower part sliding within a surrounding moveable ring member, and a bellows may be connected to the compensator housing and the moveable ring member.
  • the first fluid chamber is then formed between the piston and the compensator housing and the second fluid chamber is formed between the piston and the bellows.
  • the throttling passage may advantageously be formed by a small gap between the piston and the compensator housing.
  • a lower surface of the compensator housing is connected to the piezoelectric actuator and a closing element is connected to the end stop of the housing.
  • a moveable ring member may advantageously be provided in a borehole of the piston, the ring member being connected to a helical spring acting on the ring member and on the closing element, the helical spring being compressed by an axial extension of the piezoelectric actuator.
  • the first fluid chamber is formed between the piston and the compensator housing and that the second fluid chamber is formed between an inside surface of the borehole and the ring member.
  • the throttling passage is formed by a straight passage through the lower portion of the piston, the passage being covered by a perforated strip.
  • the metering device provides Hertzian contact between the fixed end stop surface of the outer injector housing and the top end of the valve needle under all operating conditions.
  • the thermal compensator unit according to the invention further provides high stiffness to the compression produced during the activation of the piezoelectric actuator and allows at the same time a rapid recovery of the initial position during the deactivation phase of the piezoelectric actuator. Elastic contact between the components needle, actuator, and the end stop of the outer housing is thus maintained at all times.
  • FIG 1 shows an injection valve 10 for direct-injection gasoline engines.
  • the injection valve 10 has a double tube design in which the housing 12 comprises an outer tubular member 121 and an inner tubular member 123, forming an annular fluid supply passage 14 between them.
  • Gasoline under pressure is provided to an inlet fitting 16, from where it is flows through the annular supply passage 14 and enters into an axial outlet passage 20, projecting through the lower part of the housing 12.
  • the outlet passage 20 terminates in a metering opening 22 surrounded by a valve seat which is opened or closed by the axial movement of a valve needle passing through the outlet passage 20.
  • a piezoelectric actuator 28 Upon activation of a piezoelectric actuator 28, gasoline is injected into the engine cylinder. When an excitation voltage is applied to the piezoelectric actuator 28, its length in axial direction increases by a predetermined amount. The extension in length is transmitted to the valve needle which lifts from the valve seat and begins the injection of pressurized gasoline. When the excitation voltage is terminated, the length of the piezoelectric actuator 28 decreases to its normal value and the valve needle 24 is pushed back in its closing position.
  • the outer steel housing 12 has a higher thermal coefficient of expansion than the material of the piezoelectric actuator 28, changes in the operation temperature need to be compensated by a thermal compensator unit 30 to ensure safe operation of the injector.
  • FIG. 2 shows a schematic axial cross section of the thermal compensator unit 30 of Fig. 1 in detail.
  • the compensator housing 32 contains a hydraulic piston 34 which is able to slide axially inside it.
  • the housing 32 rests via its upper surface 54 on the fixed end stop of the injector 10, while the lower end rod 48 of the piston 34 is in contact with the piezoelectric actuator 28.
  • the piston 34 and the compensator housing form a first fluid chamber 36, a second fluid chamber 38 and a small annular throttling gap 40 connecting the two fluid chambers.
  • the fluid chambers 36, 38 are filled with a hydraulic fluid, for example with silicone oil.
  • the piston 34 is pushed upward by the expansion of the piezoelectric actuator 28 and this forces the silicone oil contained inside the chamber 36 through the peripheral throttling gap 40 of the piston 34 sliding in the housing 32, thereby filling the lower oil chamber 38.
  • the ring element 42 moves downward, the lower oil chamber 38 expands during the activation phase.
  • Two rubber seals 44 and 46 seal the silicone oil containing chambers against the surrounding.
  • the volume of oil contained in the second chamber 38 can move back toward the first chamber 36 either via the annular throttling gap 40 or via a channel formed in the head of the piston 34 that connects the chambers 36 and 38 to each other.
  • a metal strip may then be spot-welded to the upper face of the piston 34, offering hydraulic leak tightness during the activation phase of the actuator and a pathway for the silicone oil during the subsequent deactivation phase, owing to the way the metal strip bends.
  • FIG. 3 shows a schematic axial cross section of a thermal compensator unit 60 according to another embodiment of the invention.
  • same reference numbers relate to same or corresponding parts.
  • the compensator housing 32 contains a piston 34 mounted axially slideable inside it.
  • the housing 32 rests via its upper surface 54 on the fixed end stop of the injector, while the lower end of the piston 34 is in contact with the piezoelectric actuator 28.
  • First 36 and second 38 fluid chambers and a small annular throttling gap 40 are formed between the piston 34 and the compensator housing 32, the two chambers 36 and 38 having the same radial cross section.
  • the piston 34 is pushed upward by the expansion of the piezoelectric actuator 28 and this forces the silicone oil contained inside the chambers 36 by the two seals 46 and 44 through the peripheral throttling gap 40, filling the lower oil chamber 38.
  • the volume of oil contained in the second chamber 38 can move back toward the first chamber 36 either via the annular throttling gap 40 or via a channel formed in the head of the piston 34 that connects the chambers 36 and 38 to each other.
  • a metal strip offering hydraulic leak tightness during the activation phase of the actuator and a pathway for the silicone oil during the subsequent deactivation phase may be spot-welded to the upper face of the piston 34.
  • FIG. 4 A further embodiment of the invention is shown in the schematic cross section of Fig. 4.
  • the compensator housing 32 of the thermal compensator unit 70 contains a piston 34, whose upper part is disposed axially slideable inside the housing 32.
  • the lower part of the piston 34 slides inside a moveable ring member 82 against which it is sealed.
  • the housing 32 rests via its upper surface 54 on the fixed end stop of the injector, while the lower end of the piston 34 is in contact with the piezoelectric actuator 28.
  • the first fluid chamber 36 is formed between the top surface of the piston 34 and the compensator housing 32.
  • a bellows 72 is connected to the compensator housing 32 and to the moveable ring member 82.
  • the second fluid chamber 38 is formed between the piston 34 and the bellows 72 and a small annular gap between the piston 34 and the housing 32 forms the throttling gap 40.
  • the piston 34 is pushed upward by the expansion of the piezoelectric actuator 28 and this forces the silicone oil contained inside the chamber 36 through the peripheral throttling gap 40, filling the lower oil chamber 38, which will expand as the ring member 82 moves downward.
  • the continual movements of oil between the chambers 36 and 38 require the presence of the bellows 72 welded to the compensator housing 32 and to the moveable ring member 82.
  • the volume of oil contained in the second chamber 38 can move back toward the first chamber 36 either via the annular throttling gap 40 or via a channel 74 formed in the head of the piston 34.
  • the opening 76 facing the first fluid chamber 36 is covered with a metal strip 80, while the opening 78 facing the second fluid chamber 38 remains uncovered.
  • the strip 80 prevents leakage of oil during activation of the actuator 28 and is able to bend under the pressure of the returning oil to open a gap for the oil to move back from the second fluid chamber 38 to the first fluid chamber 36 during the deactivation phase of the actuator 28.
  • FIG. 5 A further design of a thermal compensator unit 90 according to the invention is shown in Fig. 5.
  • the housing 32 contains a piston 34 able to slide axially inside it.
  • a closing element 96 rests via its upper surface on the fixed end stop of the injector 10 while the lower end of the housing 32 is in contact with the piezoelectric actuator 28.
  • a moveable ring member 92 is provided in a borehole 100 of the piston 34, the ring member 92 being connected to a helical spring 94 acting on the ring member 92 and the closing element 96.
  • the first fluid chamber 36 is formed between the lower surface of the piston 34 and the compensator housing 32
  • the second fluid chamber 38 is formed between the inside surface of the borehole 100 and the ring member 92.
  • a throttling passage between the first and second fluid chamber 36 and 38 is formed by a straight passage 102, extending through the lower portion of the piston 34.
  • the straight passage 102 is covered by a perforated strip 98 having a small hole to provide high hydraulic resistance to the flow of oil during the expansion of the actuator 28.
  • the piston 34 is pushed downward by the expansion of the piezoelectric actuator 28 during the activation phase of the piezoelectric actuator 28. This movement forces the silicone oil contained inside the chambers 36 through the hole formed in the strip 98, slowly filling the second fluid chamber 38.
  • the volume of oil contained in the second chamber 38 can move back toward the first chamber 36 due to the bending of the strip 98, which is welded to the piston at two points of its outer circumference only.
  • the strip 98 provides good hydraulic resistance to the flow of oil during the expansion of the actuator and is able to bend, opening a gap for the oil to move back from the first fluid chamber 38 to the second fluid chamber 36 during the deactivation phase of the actuator 28.

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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)
EP20020018666 2002-08-20 2002-08-20 Doseur avec unité de compensation thermique Expired - Lifetime EP1391608B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE2002604565 DE60204565T2 (de) 2002-08-20 2002-08-20 Dosiergerät mit Thermalkompensationseinheit
EP20020018666 EP1391608B1 (fr) 2002-08-20 2002-08-20 Doseur avec unité de compensation thermique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP20020018666 EP1391608B1 (fr) 2002-08-20 2002-08-20 Doseur avec unité de compensation thermique

Publications (2)

Publication Number Publication Date
EP1391608A1 true EP1391608A1 (fr) 2004-02-25
EP1391608B1 EP1391608B1 (fr) 2005-06-08

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Family Applications (1)

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EP20020018666 Expired - Lifetime EP1391608B1 (fr) 2002-08-20 2002-08-20 Doseur avec unité de compensation thermique

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EP (1) EP1391608B1 (fr)
DE (1) DE60204565T2 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1524427A1 (fr) * 2003-10-09 2005-04-20 Siemens Aktiengesellschaft Actionneur piezo-electrique avec compensateur
EP1731753A1 (fr) * 2005-06-06 2006-12-13 Siemens Aktiengesellschaft Injecteur et compensateur pour un injecteur
EP1887216A1 (fr) * 2006-08-02 2008-02-13 Siemens Aktiengesellschaft Arrangement thermique de compensation dans une valve d'injection
EP1972779A1 (fr) * 2007-03-19 2008-09-24 Robert Bosch Gmbh Coupleur hydraulique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1046809A2 (fr) * 1999-04-20 2000-10-25 Siemens Aktiengesellschaft Dispositif de dosage d'un fluide
US20010035164A1 (en) * 1999-10-15 2001-11-01 Irawan Rahardja Directly actuated injection valve with a composite needle
WO2002031344A1 (fr) * 2000-10-11 2002-04-18 Siemens Vdo Automotive Corporation Ensemble compensateur a double ressort pour injecteur de carburant et procede associe

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1046809A2 (fr) * 1999-04-20 2000-10-25 Siemens Aktiengesellschaft Dispositif de dosage d'un fluide
US20010035164A1 (en) * 1999-10-15 2001-11-01 Irawan Rahardja Directly actuated injection valve with a composite needle
WO2002031344A1 (fr) * 2000-10-11 2002-04-18 Siemens Vdo Automotive Corporation Ensemble compensateur a double ressort pour injecteur de carburant et procede associe
US20020047100A1 (en) * 2000-10-11 2002-04-25 Jack Lorraine Pressure responsive valve for a compensator in a solid state actuator

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1524427A1 (fr) * 2003-10-09 2005-04-20 Siemens Aktiengesellschaft Actionneur piezo-electrique avec compensateur
EP1731753A1 (fr) * 2005-06-06 2006-12-13 Siemens Aktiengesellschaft Injecteur et compensateur pour un injecteur
US7673811B2 (en) 2005-06-06 2010-03-09 Siemens Aktiengesellschaft Injection valve and compensating element for an injection valve
EP1887216A1 (fr) * 2006-08-02 2008-02-13 Siemens Aktiengesellschaft Arrangement thermique de compensation dans une valve d'injection
EP1972779A1 (fr) * 2007-03-19 2008-09-24 Robert Bosch Gmbh Coupleur hydraulique

Also Published As

Publication number Publication date
DE60204565D1 (de) 2005-07-14
DE60204565T2 (de) 2005-11-03
EP1391608B1 (fr) 2005-06-08

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