EP1803929B1 - Fluid injector and method for manufacturing a fluid injector - Google Patents
Fluid injector and method for manufacturing a fluid injector Download PDFInfo
- Publication number
- EP1803929B1 EP1803929B1 EP20050027109 EP05027109A EP1803929B1 EP 1803929 B1 EP1803929 B1 EP 1803929B1 EP 20050027109 EP20050027109 EP 20050027109 EP 05027109 A EP05027109 A EP 05027109A EP 1803929 B1 EP1803929 B1 EP 1803929B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- housing
- ring body
- fluid injector
- thermal compensator
- 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.)
- Expired - Fee Related
Links
- 239000012530 fluid Substances 0.000 title claims description 79
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 238000000034 method Methods 0.000 title claims description 14
- 238000003466 welding Methods 0.000 claims description 7
- 230000008878 coupling Effects 0.000 claims description 2
- 238000010168 coupling process Methods 0.000 claims description 2
- 238000005859 coupling reaction Methods 0.000 claims description 2
- 230000000284 resting effect Effects 0.000 claims description 2
- 239000000446 fuel Substances 0.000 description 14
- 238000002485 combustion reaction Methods 0.000 description 11
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 230000001419 dependent effect Effects 0.000 description 1
- 238000007789 sealing 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
- 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
-
- 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
- F02M61/161—Means for adjusting injection-valve lift
-
- 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
- F02M61/168—Assembling; Disassembling; Manufacturing; Adjusting
-
- 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
- F02M2200/16—Sealing of fuel injection apparatus not otherwise provided for
Definitions
- the invention relates to a fluid injector, in particular a fluid injector for metering fuel to a combustion chamber of an internal combustion engine.
- Fuel injectors are in widespread use, in particular for internal combustion engines where they may be arranged in order to dose the fluid into the intake manifold of the internal combustion engine or directly into the combustion chamber of a cylinder of the internal combustion engine.
- the invention further relates to a method for manufacturing a fluid injector.
- fluid injectors In order to meet stringent regulations concerning exhaust emissions of internal combustion engines, fluid injectors need to be designed such that they are adapted to dose fluid very precisely. In this respect, more and more fluid injectors are equipped with piezoelectric actuators.
- the respective fluid injector may be suited to dose fluid under very high pressure.
- the pressure may be, in the case of a gasoline engine, for example, in the range of up to 200 bar and in case of a Diesel engine, in the range of up to 2000 bar.
- WO 02/31344 A1 discloses a fuel injector comprising a body having a longitudinal axis, a length-changing actuator, that has first and second ends, a closure member 40 being coupled to the first end of the length-changing actuator, and a compensator assembly coupled to the second end of the actuator.
- the length-changing actuator includes first and second ends.
- the closure member is moveable between a first configuration permitting fuel injection and a second configuration preventing fuel injection.
- the length-changing actuator, and the compensator assembly are arranged in an injector housing.
- An inlet fitting is arranged at an axial end of the housing facing away from the closure member.
- EP1 457 662 A1 discloses a fluid injector with a housing having a cover which closes the housing at one of its axial ends.
- the cover comprises an inlet for fuel.
- US 6 422 482 B1 discloses a fuel injection valve with a housing, which takes in a fuel inlet nozzle that again takes in a spring.
- the invention is distinguished according to a first aspect by a fluid injector with a housing comprising a housing recess and a fluid duct both extending from one axial end of the housing into the housing.
- the fluid injector further comprises an actuator unit taken in the housing recess, a thermal compensator unit taken in the housing recess, and an inlet fitting.
- the inlet fitting comprises a fluid supply connecting part for connecting the fluid injector to a fluid supply. In that way it communicates with the fluid duct.
- the inlet fitting is designed and fixed to the housing such that it sealingly closes the housing at the one axial end of the housing.
- the fluid injector enables to be manufactured by only a few separate parts.
- the inlet fitting serves a double function of enabling a connection to a fluid supply and also forming a closing for the housing recess protecting the thermal compensator and the actuator from the environment of the fluid injector. In that way, it enables a cost effective manufacturing of the fluid injector.
- the thermal compensator unit is mechanically coupled to an internal ring body arranged in the housing recess and influencing depending on its axial position in the housing recess a characteristic of the thermal compensator unit.
- An external ring body is arranged on the outside of the housing and is mechanically coupled to the internal ring body in such a way that the respective axial positions of the internal and external ring body correlate to each other. This enables to influence the characteristic after mounting the thermal compensator unit in the housing without needing access for a tool directly in the side of the recess. In that way, a simple and precise calibration of the fluid injector is enabled. This further enables the precise calibration and at the same time to use the inlet fitting for sealingly closing the housing recess at the one axial end of the housing.
- this aspect of the invention and its further preferred embodiments may also be incorporated in a further type of fluid injector with an inlet fitting not being designed for fixing the housing such that it sealingly closes the housing recess. Instead a closing part for closing the housing recess may then be provided.
- the inlet fitting then is designed for communicating with the fluid duct.
- the inlet fitting comprises a cup shaped part being fixed to the housing for closing the housing recess at the one axial end of the housing. This enables a reliable fixation of the inlet fitting to the housing even with very high fluid pressures being applied to the inlet fitting and the fluid duct.
- the thermal compensator unit comprises a piston with a rod.
- the rod is movable relative to the housing and comprises a first spring seat.
- the thermal compensator unit further comprises a thermal compensator spring, resting with one free end on the first spring seat.
- the internal ring body forms a second spring seat for the thermal compensator spring. This may ensure a simple and robust fluid injector.
- the internal ring body is mechanically coupled to the external ring body by a calibration pin radially extending through a housing radial recess in the housing.
- the calibration pin is coupled to the internal ring and/or the external ring by a press fit connection. This is simple to manufacture and therefore may result in low cost but enables a robust connection.
- the invention is distinguished by a method for manufacturing the fluid injector according to the first aspect of the invention.
- the method comprises assembling the actuator unit and the thermal compensator unit and the internal ring in the housing recess. Further, it comprises assembling the inlet fitting on the housing, covering the housing recess and the fluid duct at the one axial end of the housing. It further comprises sealingly fixing the inlet fitting to the housing such that it sealingly closes the housing at the one axial end of the housing. It further comprises after assembling the actuator and the thermal compensator unit and the internal ring in the housing recess steps of:
- the method for manufacturing the fluid injector comprises sealingly fixing the inlet fitting to the housing by laser welding. This has the advantage of enabling a very localized but extremely well sealing fixation of the inlet fitting.
- a fluid injector may be embodied as a fuel injector, that is suitable for injecting fuel into a gasoline engine or that may be suitable for injecting fuel in a Diesel engine.
- the fluid injector comprises a housing 1 and a valve body 3.
- the valve body 3 comprises a cartridge 5 with a cartridge recess 7 and a needle 9, that is inserted into the cartridge recess 7 and is guided in an area of a guide formed in the cartridge recess 7.
- the needle 9 is of an outward opening type but it may also be of an inward opening type.
- the needle is pushed in its closing position by a return spring 11 if no further forces act on the needle.
- the return spring 11 exerts a force on the needle 9 in the closing direction of the needle 9.
- the fuel injector is preferably located in a cylinder head of an internal combustion engine and provides the combustion chamber with fluid.
- the housing 1 comprises a fluid duct 2, which may preferably be manufactured as a borehole. It further comprises a housing recess 4.
- the housing recess 4 and the fluid duct 2 both extend from one axial end of the housing into the housing.
- the one axial end of the housing 1 is the one facing away from the nozzle 15.
- the fluid duct 2 extends through the housing 1 and communicates with the nozzle 15.
- An actuator unit 13 is arranged in the housing recess 4 and is coupled to the needle 9.
- the actuator unit 13 is a piezoelectric actuator unit. Then, it comprises a stack of piezoelectric elements, which are pretensioned by a tube spring and held in-between a first and a second end cap.
- a thermal compensator unit 17 is arranged in the housing recess 4 on a side respective to the actuator unit 13 facing away from the nozzle 15.
- the thermal compensator unit 17 may, however, also be arranged on the side facing towards the nozzle 15.
- the thermal compensator unit 17 comprises a thermal compensator housing part 19, which is fixed to the housing 1 by welding, which is indicated by a small circle.
- the thermal compensator unit 17 further comprises a piston 21 with a rod 23 protruding towards the actuator unit 13.
- a first spring seat 25 is fixed to the rod 23 and serves as a seat for a thermal compensator spring 27 at one of its axial ends.
- An internal ring body 29 is arranged in the housing recess 4 and forms a second spring seat 30 at the respective other axial end of the thermal compensator spring 27.
- the piston 21 is movable relative to the housing 1.
- the thermal compensator unit is designed to compensate different thermal expansion coefficients of the actuator unit 13 and the housing 1. It preferably comprises chambers filled with a hydraulic fluid which enable in combination with the piston 21 and dependent on the spring load applied to the thermal compensator spring 27 a compensation of these changes whereas it is designed such, that it behaves as a stiff body, if the actuator unit is controlled to expand.
- the duration of the expansion of the actuator unit 13, correlating to an injection event of the fluid injector is always for a very short duration of time.
- an appropriately dimensioned throttle may be provided between respective chambers of a thermal compensator unit taking into consideration the time duration for the injection event and at the same time providing on a larger time scale a force pressure balance between respective chambers of the thermal compensator unit 7 and thereby setting the axial position of the piston 21 relative to the housing, in particular the location of the housing 1 where the thermal compensator housing part 19 is fixed to the housing.
- the internal ring body 29 is mechanically coupled to an external ring 37.
- the external ring 37 is arranged on the outside of the housing 1 and is mechanically coupled to the internal ring body 29 in such a way that the respective axial positions of the internal ring body 29 and the external ring body 37 correlate to each other.
- the internal ring body 29 does not need to have an exact ring shape. It is just formed in a way, that it is slidably movable along an inner wall of the housing recess 4 and that it forms the second spring seat 30.
- the external ring body 37 may have a shape deviating from an exact ring shape. It may, for example, have a bushing form.
- the internal ring body 29 is mechanically coupled to the external ring body 37 by a calibration pin 33, which protrudes radially from the internal ring to the external ring body 37. Further, the calibration pin 33 protrudes through a housing radial recess 35.
- the housing radial recess 35 preferably has an axial extension which is large enough to move the calibration ring during the manufacturing process of the fluid injector in an axial direction relative to the housing 1.
- the calibration pin 33 is arranged in an internal ring radial recess 31 of the internal ring body 29 in a press fit connection.
- the calibration ring 33 is arranged in an external ring recess 39 of the external ring body 37 also in a press fit connection.
- the external ring body 37 is fixed to the housing 1, preferably by laser welding. But it may also be fixed to the housing 1 by some other sort of connection known to the person skilled in the art for this purpose.
- An inlet fitting 45 comprises a cup shaped part 47 covering an axial end area of the housing 1 at an axial end of the housing 1 facing away from the nozzle 15.
- the cup shaped part 47 is sealingly connected to the housing 1, for example, by laser welding also indicated by small circles.
- the inlet fitting 45 further comprises a fluid supply connecting part 49.
- the fluid injector is coupled to a fluid supply, preferably being formed by a fuel rail via the fluid supply connecting part 49. Therefore, the fluid supply connecting part 49 comprises an inlet fitting recess 51, which extends through the fluid supply connecting part 49 in an axial direction.
- the inlet fitting recess 51 and the fluid duct 2 communicate with each other.
- the inlet fitting 45 closes the housing recess 4 and therefore protects the actuator unit 13 and also the thermal compensator unit 17 from influences from outside of the fluid injector.
- step S1 the manufacturing process is started and the housing with the valve body 3 are already provided in a preassembled state.
- a step S3 the actuator unit 13 is inserted into the housing recess 4 and the thermal compensator unit 17 together with the internal ring body 29 are inserted into the housing recess 4.
- the inlet fitting is assembled on the housing covering the housing recess at the one axial end of the housing 1. Therefore, the inlet fitting 45 is preferably pushed with its cup shaped part 47 over the axial end area of the housing 1 facing away from the nozzle 15. The cup shaped part 47 then covers the cross-section of the housing recess 4 and also of the fluid duct 2. The inlet fitting is then sealingly fixed to the housing 1. This is preferably accomplished by laser welding. It may, however, also be accomplished by some other way of fixing it sealingly to the housing 1 known to the person skilled in the art taking into consideration that it must withstand the forces acting on the fixation due to the pressure of the fluid to be dosed in the pressure range the respective injection valve is designed to operate.
- the manufacturing may then be finished in a step S7. It is preferred, however, that in a subsequent step S9, the fluid injector is calibrated, in particular that the thermal compensator is then calibrated.
- the housing preferably has the housing radial recess 35.
- the external ring body 37 is pushed onto the housing 1 in step S3. Whether this is done before the inlet fitting 45 is pushed onto the housing 1 or after that depends on whether a maximum outer diameter of the inlet fitting 45 is larger than the outer diameter of the housing which is relevant for pushing the external ring body 37 on the housing 1.
- the external ring body 37 is pushed onto the housing 1 prior to pushing the inlet fitting onto the housing 1.
- the calibration ring is assembled with the internal ring body 29 and the external ring body 37 prior to assembling the inlet fitting 45 and preferably even before the thermal compensator housing part 19 and the piston 21 are assembled in the housing recess 4.
- the calibration pin 33 is fixed in the internal ring radial recess 31 by a press fit connection. It is also preferably fixed in the external ring recess 39 by a press fit connection. It may, however, also be fixed in some other way known for being suitable to a person skilled in the art. For example, it may be fixed by a screw connection.
- the inlet fitting is connected to a fluid supply and is supplied with fluid of a given pressure or a given pressure variation for the calibration process.
- the axial position of the external ring body 37 is then varied in order to obtain a given characteristic of the thermal compensator.
- the temperature of the fluid injector may also be varied during the calibration process and/or the amount of fuel to be dosed and/or actually dosed may be varied.
- a characteristic of the thermal compensator unit is influenced by setting the pretensioning force of the thermal compensator spring 27. In that way, also a calibration for the fluid dosing characteristic of the fluid injector may be set. The characteristic of the thermal compensator may therefore be representative for the characteristic of the fluid injector in view of fluid dosing.
- the external ring body 37 is kept in the respective axial position obtained during the calibration process and is fixed in this axial position by fixing it to the housing, e.g. by laser welding or some other sort of connection technique known to the person skilled in the art for this purpose in a step S11. After step S11, no further axial movement of the external ring body 37 is possible.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Fuel-Injection Apparatus (AREA)
Description
- The invention relates to a fluid injector, in particular a fluid injector for metering fuel to a combustion chamber of an internal combustion engine. Fuel injectors are in widespread use, in particular for internal combustion engines where they may be arranged in order to dose the fluid into the intake manifold of the internal combustion engine or directly into the combustion chamber of a cylinder of the internal combustion engine. The invention further relates to a method for manufacturing a fluid injector.
- In order to meet stringent regulations concerning exhaust emissions of internal combustion engines, fluid injectors need to be designed such that they are adapted to dose fluid very precisely. In this respect, more and more fluid injectors are equipped with piezoelectric actuators.
- In order to enhance the combustion-process in view of the creation of unwanted emissions, the respective fluid injector may be suited to dose fluid under very high pressure. The pressure may be, in the case of a gasoline engine, for example, in the range of up to 200 bar and in case of a Diesel engine, in the range of up to 2000 bar.
-
WO 02/31344 A1 -
EP1 457 662 A1 discloses a fluid injector with a housing having a cover which closes the housing at one of its axial ends. The cover comprises an inlet for fuel. -
US 6 422 482 B1 discloses a fuel injection valve with a housing, which takes in a fuel inlet nozzle that again takes in a spring. - According to a first aspect of the invention, it is the object to create a fluid injector, which enables to be manufactured in a simple way. According to a further aspect of the invention, it is the object to create a method for manufacturing a fluid injector which is simple.
- The object is achieved by the features of the independent claims. Advantageous embodiments of the invention are given in the sub-claims.
- The invention is distinguished according to a first aspect by a fluid injector with a housing comprising a housing recess and a fluid duct both extending from one axial end of the housing into the housing. The fluid injector further comprises an actuator unit taken in the housing recess, a thermal compensator unit taken in the housing recess, and an inlet fitting. The inlet fitting comprises a fluid supply connecting part for connecting the fluid injector to a fluid supply. In that way it communicates with the fluid duct. The inlet fitting is designed and fixed to the housing such that it sealingly closes the housing at the one axial end of the housing. The fluid injector enables to be manufactured by only a few separate parts. The inlet fitting serves a double function of enabling a connection to a fluid supply and also forming a closing for the housing recess protecting the thermal compensator and the actuator from the environment of the fluid injector. In that way, it enables a cost effective manufacturing of the fluid injector.
- The thermal compensator unit is mechanically coupled to an internal ring body arranged in the housing recess and influencing depending on its axial position in the housing recess a characteristic of the thermal compensator unit.
- An external ring body is arranged on the outside of the housing and is mechanically coupled to the internal ring body in such a way that the respective axial positions of the internal and external ring body correlate to each other. This enables to influence the characteristic after mounting the thermal compensator unit in the housing without needing access for a tool directly in the side of the recess. In that way, a simple and precise calibration of the fluid injector is enabled. This further enables the precise calibration and at the same time to use the inlet fitting for sealingly closing the housing recess at the one axial end of the housing. It is to be noted, however, that this aspect of the invention and its further preferred embodiments may also be incorporated in a further type of fluid injector with an inlet fitting not being designed for fixing the housing such that it sealingly closes the housing recess. Instead a closing part for closing the housing recess may then be provided. The inlet fitting then is designed for communicating with the fluid duct.
- According to an advantageous embodiment of the first aspect, the inlet fitting comprises a cup shaped part being fixed to the housing for closing the housing recess at the one axial end of the housing. This enables a reliable fixation of the inlet fitting to the housing even with very high fluid pressures being applied to the inlet fitting and the fluid duct.
- According to a further preferred embodiment of the first aspect, the thermal compensator unit comprises a piston with a rod. The rod is movable relative to the housing and comprises a first spring seat. The thermal compensator unit further comprises a thermal compensator spring, resting with one free end on the first spring seat. The internal ring body forms a second spring seat for the thermal compensator spring. This may ensure a simple and robust fluid injector.
- According to a further preferred embodiment of the first aspect, the internal ring body is mechanically coupled to the external ring body by a calibration pin radially extending through a housing radial recess in the housing. This enables a simple to manufacture fluid injector, with a precise calibration being possible.
- In this respect, it is advantageous if the calibration pin is coupled to the internal ring and/or the external ring by a press fit connection. This is simple to manufacture and therefore may result in low cost but enables a robust connection.
- According to a second aspect, the invention is distinguished by a method for manufacturing the fluid injector according to the first aspect of the invention. The method comprises assembling the actuator unit and the thermal compensator unit and the internal ring in the housing recess. Further, it comprises assembling the inlet fitting on the housing, covering the housing recess and the fluid duct at the one axial end of the housing. It further comprises sealingly fixing the inlet fitting to the housing such that it sealingly closes the housing at the one axial end of the housing. It further comprises after assembling the actuator and the thermal compensator unit and the internal ring in the housing recess steps of:
- assembling the external ring body to the housing on the outside of the housing,
- mechanically coupling the external ring body to the internal ring body in such a way that the respective axial positions of the internal and external ring body correlate to each other,
- varying the axial position of the external ring body for calibrating the fluid injector in view of a given characteristic of the thermal compensator unit, and
- fixing the external ring to the housing, preventing further axial movement of the external ring after the calibration has been finished. The advantages of the method for manufacturing the fluid injector correspond to the advantages of the first aspect of the invention and its preferred embodiments.
- According to a preferred embodiment of the method for manufacturing the fluid injector, it comprises sealingly fixing the inlet fitting to the housing by laser welding. This has the advantage of enabling a very localized but extremely well sealing fixation of the inlet fitting.
- Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. Exemplary embodiments of the invention are explained in the following with the aid of schematic drawings. These are as follows:
- FIG. 1
- a fluid injector and
- FIG. 2
- a flowchart for manufacturing the fluid injector.
- Elements of the same design and function that occur in different illustrations are identified by the same reference character.
- A fluid injector may be embodied as a fuel injector, that is suitable for injecting fuel into a gasoline engine or that may be suitable for injecting fuel in a Diesel engine. The fluid injector comprises a housing 1 and a valve body 3. The valve body 3 comprises a
cartridge 5 with acartridge recess 7 and aneedle 9, that is inserted into thecartridge recess 7 and is guided in an area of a guide formed in thecartridge recess 7. Theneedle 9 is of an outward opening type but it may also be of an inward opening type. The needle is pushed in its closing position by areturn spring 11 if no further forces act on the needle. Thereturn spring 11 exerts a force on theneedle 9 in the closing direction of theneedle 9. - The fuel injector is preferably located in a cylinder head of an internal combustion engine and provides the combustion chamber with fluid.
- The housing 1 comprises a
fluid duct 2, which may preferably be manufactured as a borehole. It further comprises ahousing recess 4. Thehousing recess 4 and thefluid duct 2 both extend from one axial end of the housing into the housing. The one axial end of the housing 1 is the one facing away from thenozzle 15. Thefluid duct 2 extends through the housing 1 and communicates with thenozzle 15. Anactuator unit 13 is arranged in thehousing recess 4 and is coupled to theneedle 9. Preferably, theactuator unit 13 is a piezoelectric actuator unit. Then, it comprises a stack of piezoelectric elements, which are pretensioned by a tube spring and held in-between a first and a second end cap. - A
thermal compensator unit 17 is arranged in thehousing recess 4 on a side respective to theactuator unit 13 facing away from thenozzle 15. In an alternative embodiment, thethermal compensator unit 17 may, however, also be arranged on the side facing towards thenozzle 15. - In the embodiment according to
FIG. 1 , thethermal compensator unit 17 comprises a thermalcompensator housing part 19, which is fixed to the housing 1 by welding, which is indicated by a small circle. Thethermal compensator unit 17 further comprises apiston 21 with arod 23 protruding towards theactuator unit 13. A first spring seat 25 is fixed to therod 23 and serves as a seat for athermal compensator spring 27 at one of its axial ends. - An
internal ring body 29 is arranged in thehousing recess 4 and forms asecond spring seat 30 at the respective other axial end of thethermal compensator spring 27. Thepiston 21 is movable relative to the housing 1. The thermal compensator unit is designed to compensate different thermal expansion coefficients of theactuator unit 13 and the housing 1. It preferably comprises chambers filled with a hydraulic fluid which enable in combination with thepiston 21 and dependent on the spring load applied to the thermal compensator spring 27 a compensation of these changes whereas it is designed such, that it behaves as a stiff body, if the actuator unit is controlled to expand. In this respect, it is to be noted, that the duration of the expansion of theactuator unit 13, correlating to an injection event of the fluid injector, is always for a very short duration of time. Therefore, an appropriately dimensioned throttle may be provided between respective chambers of a thermal compensator unit taking into consideration the time duration for the injection event and at the same time providing on a larger time scale a force pressure balance between respective chambers of thethermal compensator unit 7 and thereby setting the axial position of thepiston 21 relative to the housing, in particular the location of the housing 1 where the thermalcompensator housing part 19 is fixed to the housing. - The
internal ring body 29 is mechanically coupled to anexternal ring 37. Theexternal ring 37 is arranged on the outside of the housing 1 and is mechanically coupled to theinternal ring body 29 in such a way that the respective axial positions of theinternal ring body 29 and theexternal ring body 37 correlate to each other. It is to be noted, that theinternal ring body 29 does not need to have an exact ring shape. It is just formed in a way, that it is slidably movable along an inner wall of thehousing recess 4 and that it forms thesecond spring seat 30. Also, theexternal ring body 37 may have a shape deviating from an exact ring shape. It may, for example, have a bushing form. - The
internal ring body 29 is mechanically coupled to theexternal ring body 37 by acalibration pin 33, which protrudes radially from the internal ring to theexternal ring body 37. Further, thecalibration pin 33 protrudes through a housing radial recess 35. The housing radial recess 35 preferably has an axial extension which is large enough to move the calibration ring during the manufacturing process of the fluid injector in an axial direction relative to the housing 1. Preferably, thecalibration pin 33 is arranged in an internalring radial recess 31 of theinternal ring body 29 in a press fit connection. Preferably, thecalibration ring 33 is arranged in anexternal ring recess 39 of theexternal ring body 37 also in a press fit connection. Theexternal ring body 37 is fixed to the housing 1, preferably by laser welding. But it may also be fixed to the housing 1 by some other sort of connection known to the person skilled in the art for this purpose. - An inlet fitting 45 comprises a cup shaped
part 47 covering an axial end area of the housing 1 at an axial end of the housing 1 facing away from thenozzle 15. The cup shapedpart 47 is sealingly connected to the housing 1, for example, by laser welding also indicated by small circles. The inlet fitting 45 further comprises a fluidsupply connecting part 49. - In its arrangement in the internal combustion engine, the fluid injector is coupled to a fluid supply, preferably being formed by a fuel rail via the fluid
supply connecting part 49. Therefore, the fluidsupply connecting part 49 comprises aninlet fitting recess 51, which extends through the fluidsupply connecting part 49 in an axial direction. Theinlet fitting recess 51 and thefluid duct 2 communicate with each other. The inlet fitting 45 closes thehousing recess 4 and therefore protects theactuator unit 13 and also thethermal compensator unit 17 from influences from outside of the fluid injector. - In
FIG. 2 , an example is given how the fluid injector may be manufactured. In a step S1, the manufacturing process is started and the housing with the valve body 3 are already provided in a preassembled state. - In a step S3, the
actuator unit 13 is inserted into thehousing recess 4 and thethermal compensator unit 17 together with theinternal ring body 29 are inserted into thehousing recess 4. - In a step S5, the inlet fitting is assembled on the housing covering the housing recess at the one axial end of the housing 1. Therefore, the inlet fitting 45 is preferably pushed with its cup shaped
part 47 over the axial end area of the housing 1 facing away from thenozzle 15. The cup shapedpart 47 then covers the cross-section of thehousing recess 4 and also of thefluid duct 2. The inlet fitting is then sealingly fixed to the housing 1. This is preferably accomplished by laser welding. It may, however, also be accomplished by some other way of fixing it sealingly to the housing 1 known to the person skilled in the art taking into consideration that it must withstand the forces acting on the fixation due to the pressure of the fluid to be dosed in the pressure range the respective injection valve is designed to operate. - The manufacturing may then be finished in a step S7. It is preferred, however, that in a subsequent step S9, the fluid injector is calibrated, in particular that the thermal compensator is then calibrated. In order to make this calibration possible, the housing preferably has the housing radial recess 35. The
external ring body 37 is pushed onto the housing 1 in step S3. Whether this is done before the inlet fitting 45 is pushed onto the housing 1 or after that depends on whether a maximum outer diameter of the inlet fitting 45 is larger than the outer diameter of the housing which is relevant for pushing theexternal ring body 37 on the housing 1. - In the preferred embodiment, however, the
external ring body 37 is pushed onto the housing 1 prior to pushing the inlet fitting onto the housing 1. Preferably, also the calibration ring is assembled with theinternal ring body 29 and theexternal ring body 37 prior to assembling the inlet fitting 45 and preferably even before the thermalcompensator housing part 19 and thepiston 21 are assembled in thehousing recess 4. This enables to axially position theexternal ring body 37 precisely in order to insert thecalibration pin 33 into the internalring radial recess 31. Preferably, thecalibration pin 33 is fixed in the internalring radial recess 31 by a press fit connection. It is also preferably fixed in theexternal ring recess 39 by a press fit connection. It may, however, also be fixed in some other way known for being suitable to a person skilled in the art. For example, it may be fixed by a screw connection. - In the step S9, the inlet fitting is connected to a fluid supply and is supplied with fluid of a given pressure or a given pressure variation for the calibration process. The axial position of the
external ring body 37 is then varied in order to obtain a given characteristic of the thermal compensator. For that purpose, the temperature of the fluid injector may also be varied during the calibration process and/or the amount of fuel to be dosed and/or actually dosed may be varied. - By varying the axial position of the
internal ring body 29, a characteristic of the thermal compensator unit is influenced by setting the pretensioning force of thethermal compensator spring 27. In that way, also a calibration for the fluid dosing characteristic of the fluid injector may be set. The characteristic of the thermal compensator may therefore be representative for the characteristic of the fluid injector in view of fluid dosing. - After the calibration process has been finished, the
external ring body 37 is kept in the respective axial position obtained during the calibration process and is fixed in this axial position by fixing it to the housing, e.g. by laser welding or some other sort of connection technique known to the person skilled in the art for this purpose in a step S11. After step S11, no further axial movement of theexternal ring body 37 is possible.
Claims (7)
- Fluid injector with a housing (1) comprising a housing recess (4) and a fluid duct (2) both extending from one axial end of the housing (1) into the housing (1),- an actuator unit (13) taken in the housing recess (4),- a thermal compensator unit (17) taken in the housing recess (4),- an inlet fitting (45) comprising a fluid supply connecting part (49) for connecting the fluid injector to a fluid supply, the inlet fitting (45) being designed and fixed to the housing (1) such that it sealingly closes the housing at the one axial end of the housing (1), characterized in that the thermal compensator unit (17) being mechanically coupled to an internal ring body (29) arranged in the housing recess (4) and influencing depending on its axial position in the housing recess (4) a characteristic of the thermal compensator unit (17), an external ring body (37) being arranged on the outside of the housing (1) and being mechanically coupled to the internal ring body (29) in such a way that the respective axial positions of the internal and the external ring body (29, 37) correlate to each other.
- Fluid injector according to claim 1, with the inlet fitting (45) comprising a cup shaped part (47) being fixed to the housing (1) for closing the housing recess (4) at the one axial end of the housing (1).
- Fluid injector according to one of the previous claims, with said thermal compensator unit (17) comprising a piston (21) with a rod (23), the rod (23) being movable relative to the housing (1) and comprising a first spring seat (25), and the thermal compensator unit (17) further comprising a thermal compensator spring (27), resting with one free end on the first spring seat (25), and with the internal ring body (29) forming a second spring seat (30) for the thermal compensator spring (27).
- Fluid injector according to one of the previous claims, with the internal ring body (29) being mechanically coupled to the external ring body (37) by a calibration pin (33) radially extending through a housing radial recess (35) in the housing (1).
- Fluid injector according to claim 4, with the calibration pin (33) being coupled to the internal ring body (29) and/or the external ring body (37) by a press fit connection.
- Method for manufacturing a fluid injector according to one of the previous claims comprising:- assembling the actuator unit (13) and the thermal compensator unit (17) and the internal ring body (29) in the housing recess (4),- assembling the inlet fitting (45) on the housing (1), covering the housing recess (4) and the fluid duct (2) at the one axial end of the housing (1),- sealingly fixing the inlet fitting (45) to the housing (1) such that it sealingly closes the housing at the one axial end of the housing (1),- assembling the external ring to the housing on the outside of the housing,- mechanically coupling the external ring body (37) to the internal ring body (29) in such a way that the respective axial positions of the internal and external ring body (29, 37) correlate to each other,- varying the axial position of the external ring body (37) for calibrating the fluid injector in view of a given characteristic of the thermal compensator unit (17) and- fixing the external ring body (37) to the housing (1) preventing further axial movement of the external ring body (37) after the calibration has been finished.
- Method according to claim 6, comprising sealingly fixing the inlet fitting (45) to the housing (1) comprising laser welding.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE200560020172 DE602005020172D1 (en) | 2005-12-12 | 2005-12-12 | Injection valve and manufacturing method of such an injection valve |
EP20050027109 EP1803929B1 (en) | 2005-12-12 | 2005-12-12 | Fluid injector and method for manufacturing a fluid injector |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP20050027109 EP1803929B1 (en) | 2005-12-12 | 2005-12-12 | Fluid injector and method for manufacturing a fluid injector |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1803929A1 EP1803929A1 (en) | 2007-07-04 |
EP1803929B1 true EP1803929B1 (en) | 2010-03-24 |
Family
ID=36129942
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20050027109 Expired - Fee Related EP1803929B1 (en) | 2005-12-12 | 2005-12-12 | Fluid injector and method for manufacturing a fluid injector |
Country Status (2)
Country | Link |
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EP (1) | EP1803929B1 (en) |
DE (1) | DE602005020172D1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2080895B1 (en) * | 2008-01-17 | 2011-10-19 | Continental Automotive GmbH | Thermal compensation arrangement and injection valve |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19849203A1 (en) * | 1998-10-26 | 2000-04-27 | Bosch Gmbh Robert | Fuel injection valve for I.C engines with expansion compensated piezoelectric actuators |
WO2002031349A1 (en) * | 2000-10-11 | 2002-04-18 | Siemens Vdo Automotive Corporation | Compensator assembly having a pressure responsive valve for a solid state actuator of a fuel injector |
ITBO20010280A1 (en) * | 2001-05-08 | 2002-11-08 | Magneti Marelli Spa | FUEL INJECTOR WITH PIEZOELECTRIC ACTUATOR |
DE502004002718D1 (en) * | 2003-02-27 | 2007-03-15 | Bosch Gmbh Robert | Fuel injector |
DE10310297A1 (en) * | 2003-03-10 | 2004-09-23 | Robert Bosch Gmbh | Fuel injector |
-
2005
- 2005-12-12 DE DE200560020172 patent/DE602005020172D1/en active Active
- 2005-12-12 EP EP20050027109 patent/EP1803929B1/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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EP1803929A1 (en) | 2007-07-04 |
DE602005020172D1 (en) | 2010-05-06 |
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