WO2014060799A1 - Optical system for the measurement of the displacement of a movable body drowned in a fluid - Google Patents

Optical system for the measurement of the displacement of a movable body drowned in a fluid Download PDF

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Publication number
WO2014060799A1
WO2014060799A1 PCT/IB2013/000815 IB2013000815W WO2014060799A1 WO 2014060799 A1 WO2014060799 A1 WO 2014060799A1 IB 2013000815 W IB2013000815 W IB 2013000815W WO 2014060799 A1 WO2014060799 A1 WO 2014060799A1
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WO
WIPO (PCT)
Prior art keywords
holes
injector
optical system
fixed body
hole
Prior art date
Application number
PCT/IB2013/000815
Other languages
French (fr)
Inventor
Riccardo AMIRANTE
Carlo CORATELLA
Luciano Andrea CATALANO
Original Assignee
Politecnico Di Bari
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Publication date
Application filed by Politecnico Di Bari filed Critical Politecnico Di Bari
Publication of WO2014060799A1 publication Critical patent/WO2014060799A1/en

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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
    • F02M47/00—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure
    • F02M47/02—Fuel-injection apparatus operated cyclically with fuel-injection valves actuated by fluid pressure of accumulator-injector type, i.e. having fuel pressure of accumulator tending to open, and fuel pressure in other chamber tending to close, injection valves and having means for periodically releasing that closing pressure
    • F02M47/027—Electrically actuated valves draining the chamber to release the closing pressure
    • 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
    • F02M65/00—Testing fuel-injection apparatus, e.g. testing injection timing ; Cleaning of fuel-injection apparatus
    • F02M65/005—Measuring or detecting injection-valve lift, e.g. to determine injection timing
    • 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
    • F02M2200/24—Fuel-injection apparatus with sensors
    • F02M2200/242—Displacement sensors
    • 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
    • F02M2200/24—Fuel-injection apparatus with sensors
    • F02M2200/245—Position sensors, e.g. Hall sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
    • G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
    • G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
    • G01D5/342—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells the sensed object being the obturating part

Definitions

  • the invention relates to an optical system, for the measurement of the displacement of a movable body drowned in a fluid.
  • the present invention relates to an optical system for the instant measurement of the displacement, in a tight chamber, of the control piston or of the nozzle needle of an injector for common rail systems or systems for direct injection of diesel fuel.
  • the common rail is a fuel feeding system mounted on diesel engines characterized by the presence of a low-pressure pump, in series with a high-pressure pump, a common high- pressure accumulation rail for fuel and electronically-controlled injectors.
  • the high pressure pump pressurizes the fuel and transfers it to the common high-pressure rail which acts as a storage tank.
  • the pressure is controlled by means of a PWM solenoid valve so as to maintain in the common rail the pressure required by the electronic control unit.
  • control chamber located above and one below the nozzle needle valve of the sprayer, respectively named "control chamber” and "delivery chamber”.
  • the upper compartment, control chamber has an outlet controlled by a solenoid or piezoelectric valve devoted to control the injector opening and closing.
  • a solenoid or piezoelectric valve devoted to control the injector opening and closing.
  • the upper compartment of the control piston empties thanks to the lift of the ball valve located on the outlet of control chamber, determining an abrupt pressure drop; the pressure in the lower compartment, the delivery chamber, determines the force that induces the opening of the needle and the beginning of injection process in the combustion chamber.
  • the injection ends only when the electric control of the solenoid valve is interrupted and the increased pressure in the control chamber determines the closure of the nozzle needle valve of the sprayer.
  • At least one pre-injection is possible, aimed at raising pressure and temperature in the combustion chamber, followed by one or more main injections and some post-injections.
  • the common rail systems can thus reduce the noise level and the high pressure peaks and obtain a more regular combustion, thanks to which emissions of unburned gases and fuel consumption are reduced, achieving, at the same time, a considerable increase in performance.
  • optical systems for measurement purposes, in order of half a millimeter, is motivated by their ability to ensure high standards of cleanliness of the signal, free from electromagnetic interference.
  • EP 0078987 Bl entitled "Fuel injection detecting system for a diesel engine” with priority date 11.11.1981 relative to a fuel injection detecting system for diesel engines comprising: a lift sensor to generate a signal (SI) variable in function of the displacement of the shutter, and a comparator that allows comparing the voltage signal (SI) with a reference voltage (VREF) and generating a binary signal (S2) representing the comparison result;
  • WO 82/01069 Al entitled "Needle position sensing system for needle and poppet valve fuel injectors" with a priority date of 15.09.1980 relating to a system for detecting the position of the needle of an injector coupled within said injector and displaceable between open and closed positions by means of a spring positioned within a chamber and coupled to said needle;
  • the detection system comprises: a passageway in said fuel injector for establishing communication with said chamber from a location external to said fuel injector, a magnetic sensor, a proximity detector, to detect displacements of said sensor, sized to move within said passage, and a sensor holder aligned with said passage for guiding said detector in a predetermined position with respect to said needle and to maintain said detector in a fixed position after said detection means are completely inserted inside said support means.
  • optical systems are very expensive as being based on laser light sources.
  • the operating principle proposed in document DE4105270A1 consists of coupling the movable or deformable object to the emitter or to the receiver or to an optical system consisting of a lens or a mirror; the reduction of light intensity is obtained by diverting the light beam or moving the receiver or the transmitter.
  • the operating principle proposed for the detection of the displacement of the control piston of an injector is based on a mirror mounted on the movable body and not on a shielding body coincident with the movable body. It should also be noted that said optical systems for the measurement of the displacement suffer from the contamination of the measuring ambient by the liquids normally present in the measuring volume or drawing through the imperfections of the seals.
  • Purpose of the present invention is to solve said drawbacks through the realization of an optical system utilizing a transducer, or an optical sensor, operating in a sealed measuring chamber and self-cleaning that allows the control and diagnostics of the operation of any type injectors, also with gasoline feeding, as well as other mechanical components furniture drowned in a fluid.
  • the new optical system according to the here presented invention allows to reduce the high costs for the realization of the sensors currently used for this application and, at the same time, to solve the known problems of the existing electromagnetic devices, affected by the magnetic fields generated by coil of the same injector at the time of excitation of its solenoid valve.
  • the system for control and diagnostics of the operation of injectors for fuel injection systems utilizing an optical sensor according to the present invention, provides for a remarkable cleaning of the signal transmitted to the electromagnetic devices, repeatability conditions and extremely low costs of realization.
  • the optical system according to the present invention ensures a reliable instantaneous measurement of the injector opening, making available a low cost tool for large scale testing of the injectors and the possibility to produce in series motors equipped with a control and real time diagnostic system for injectors.
  • FIG. 1 - a perspective exploded view, with parts partially cut away, of the main components of the optical system applied to an injector for common rail systems;
  • fig. 2 - a schematic view illustrating the optical access of the overlap of the through holes made respectively on the injector and on the control piston;
  • fig. 3 - a diagram illustrating the variation of the output signal emitted by the photoreceiver with the increase in the percentage of overlap between the three holes;
  • FIG. 4 - a perspective view with parts partially removed of an injector provided with a seal and drainage system of fuel;
  • the optical system for measuring displacement comprises a at least one photodiode emitter 1 and at least one transistor photoreceiver 2, acting in the field of the infrared or any other light frequencies not interfering with other light sources, including the external source of light.
  • the photoemitter 1 and the photoreceiver 2 are allocated in two spaced plate 5 of polycarbonate, or other transparent material, having two cylindrical pins 6 forced or fixed in any other way in two coaxial holes 3, approximate 4 mm diameter, made on the body of the injector 8.
  • Photoemitter 1 and photoreceiver 2 are forced into the holes 9 formed in the two plates 5 of polycarbonate, transparent to infrared (or other light frequency) beam, acting as support for the two optical devices, or alternatively, in other embodiments of the system, photoemitter and photoreceiver, may be allocated directly in the holes 3 formed on the body 8 of the injector.
  • polycarbonate is a material which can be easily crossed by beams of infrared light or other frequency, since it does not cause significant scattering phenomena, and therefore does not deteriorate the readability of the signal passing through it.
  • the operation principle of the system uses the photoemitter 1 for emitting an infrared or other light frequency beam that, passing through suitable holes 3 made on the body 8 of the injector and through a hole 4 on the control piston 7, reaches the photoreceiver 2, raising its saturation level.
  • the through hole 4 on the control piston 7, has a diameter of about 1.5 mm and, in standby mode (injector closed), the geometric center is about 1.7 mm from that of said two holes 3, on the injector body 8.
  • the intensity of the light signal received by the photoreceiver 2 depends on the reciprocal position between the hole drilled on the control piston 7 of the injector and the holes drilled on the body 3 of the injector 8 and it is therefore indicative of the displacement of the control piston.
  • the light signal once reached the photoreceiver 2, is converted into a voltage signal that can be measured by any data acquisition system.
  • the circumference C4, radius R4 (for example approximately 0.75 mm), indicates the hole 4 on the piston, whose alternative motion with respect to the circumference R3, radius C3 (for example approximately 2 mm), indicating one of the two coaxial holes 3 on the injector body 8, produces an output voltage by the photoreceiver 2 variable in function of the area A identified by the intersection between the two circumferences.
  • the photoreceiver provides an indicative voltage depending on the intensity of the light signal perceived due to the displacement of the control piston.
  • the maximum lift of the control piston corresponds to the minimum percentage of juxtaposition, and, consequently, the minimum voltage signal emitted by the photoreceiver.
  • the diagram of figure 3 refers to the static tests performed on the system and shows the relationship between the signal emitted by the photo receiver and the percentage of juxtaposition between the two circumferences C3 and C4.
  • intersection area A between the aforementioned circumferences and the distance between their centers is approximately linear for a wide range.
  • the distance between the center 04 of hole 4 practiced on the control piston 7 and the center 03 of the two holes 3 on the injector body 8 depends on the diameters of the holes, on the maximum measuring displacement and on and the demand for linearity of the system.
  • said distance measured along the longitudinal axis of the injector or of the control piston, is about 1.7 mm.
  • the geometry illustrated in the preferred embodiment of the system according to the present invention shows, between the standby mode and end mode of the injector displacement, an optimal signal variation of output voltage, indicative of the displacement.
  • the system here described operates in a zone of the injector that is affected by the presence of leakage from the sprayer and the coupling cylinder / piston of the control piston. This fuel fills the body of the injector and is drained at the top, through suitable pipes.
  • the system has also self-cleaning autonomous ability, useful in the starting phase or in case of malfunction.
  • the optical system according to the present invention excels hence for reliability and repeatability without incurring in significant distortion problems of the signal representative of the displacement.
  • Figure 5 is an example of the experimental remark relating to two consecutive injections of an injector provided with the system according to the invention.
  • a source of compressed air whose pressure is totally compatible with that required by the system according to the invention, is already available in engines equipped with supercharging turbo-groups; the required flow to the system is instead absolutely negligible. Its simplicity is evident even with regard to changes that have to be made to the mechanics of the system currently on market.
  • the drainage system finally, does not hinder the opening of the injector.
  • the geometric shape of the lights for the optical access could be trivially circular or other shape.
  • this optical system could also provide the application of the photodiodes housing in the notches on the piston, thus excluding the need for machining, although of reduced entity, to be done on the command rod and the injector body, with a further reduction in the time of implementation of the system.
  • optical system according to the invention illustrated in the figures is applied for the measurement of the displacement of the control piston of an injector for common rail systems; the system is, however, generally applicable, with appropriate modifications of the dimensions and the geometry and/or with a different arrangement of the components, for the measurement of the displacement of the control piston or shutter needle of any type injectors, even with gasoline feeding (direct injection), as well as other mechanical components furniture drowned in a fluid.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Optical Transform (AREA)
  • Fuel-Injection Apparatus (AREA)

Abstract

The optical system allows the detection of the opening and then the control and diagnostics of injectors of any type, with any type of petrol and supply, as well as other mechanical moving parts drowned in a fluid. This system includes: - a measuring environment with an almost watertight chamber, - a fixed body, such as the body (8) of an injector, having at least two coaxial holes (3) of any geometry, - movable body, such as a control piston (7), having at least one through hole (4) of any geometry, - at least one diode (1) for the emission of an infrared or other light frequency beam placed in one of said coaxial holes (3) drilled on the fixed body, - at least one photoreceiver transistor (2) for receiving said beam, positioned frontally to said diode, and placed in the second of said coaxial holes (3) formed on the fixed body, - an electronic circuit for the transmission and reception of the light signal. The diode (1) emits an infrared or other light frequency beam which, passing through the coaxial holes (3) on the fixed body and the through hole (4) on the movable body, reaches the photoreceiver (2) that produces an indicative voltage derived from the intensity of the received light signal which is due to the displacement of the movable body with respect to the fixed body, said voltage being proportional to the percentage of juxtaposition between said through holes of the fixed body and said through hole of the movable body.

Description

DESCRIPTION
Optical system for the measurement of the displacement of a movable body drowned in a fluid
The invention relates to an optical system, for the measurement of the displacement of a movable body drowned in a fluid.
More particularly, the present invention relates to an optical system for the instant measurement of the displacement, in a tight chamber, of the control piston or of the nozzle needle of an injector for common rail systems or systems for direct injection of diesel fuel.
The common rail is a fuel feeding system mounted on diesel engines characterized by the presence of a low-pressure pump, in series with a high-pressure pump, a common high- pressure accumulation rail for fuel and electronically-controlled injectors.
The high pressure pump pressurizes the fuel and transfers it to the common high-pressure rail which acts as a storage tank.
The pressure is controlled by means of a PWM solenoid valve so as to maintain in the common rail the pressure required by the electronic control unit.
The fuel then reaches to the injectors and occupies two compartments, one located above and one below the nozzle needle valve of the sprayer, respectively named "control chamber" and "delivery chamber".
The two opposing forces, exerted hydrostatically from the fuel, neutralize each other and the needle remains in the closed position thanks to the force applied by a spring.
The upper compartment, control chamber, has an outlet controlled by a solenoid or piezoelectric valve devoted to control the injector opening and closing. When the valve is excited by the opening signal, the upper compartment of the control piston empties thanks to the lift of the ball valve located on the outlet of control chamber, determining an abrupt pressure drop; the pressure in the lower compartment, the delivery chamber, determines the force that induces the opening of the needle and the beginning of injection process in the combustion chamber. The injection ends only when the electric control of the solenoid valve is interrupted and the increased pressure in the control chamber determines the closure of the nozzle needle valve of the sprayer.
In this way, thanks to the great speed of reaction of the control valves, it is possible to obtain more injections per working cycle.
Therefore at least one pre-injection is possible, aimed at raising pressure and temperature in the combustion chamber, followed by one or more main injections and some post-injections.
Thanks to the pre-injection and the subdivision of the main flow, the pressure in the combustion chamber rises more gradually: the common rail systems can thus reduce the noise level and the high pressure peaks and obtain a more regular combustion, thanks to which emissions of unburned gases and fuel consumption are reduced, achieving, at the same time, a considerable increase in performance.
Due to the influence exerted by the displacement (rise) of the needle valve on the timing of the injection, accurate measurements of its position are essential for a more complete and precise configuration of the injection process, in view of preventive (testing), real-time and diagnostic controls of the injectors.
The need for an adequate system of measurement that determines the lift of the needle nozzle during the injection cycle has been, for some years, the final goal of study of the global scientific community, as well as of some companies in the sector, which have proposed solutions based on optical or inductive techniques which proved to be not fully satisfactory for the quality of results and for the production costs.
The reliability and quality of the experimental measurements of the sensors currently used is in fact compromised by electromagnetic interference generated by the electric coil placed in the injector head, which induce an unacceptable dispersion of data related to the signal of displacement of the piston control in conjunction with the current pulse received from the control unit.
The use of optical systems for measurement purposes, in order of half a millimeter, is motivated by their ability to ensure high standards of cleanliness of the signal, free from electromagnetic interference.
Some patented documents related to the proposed technology are cited as example:
• DE 19743156 Al titled "Position or displacement sensor for needle valve in the fuel injection valve for motor vehicle" with a priority date of 30.09.1997 referring to an optical sensor having an optical measurement probe which directs two coherently focused light beams onto the needle, where they are diffracted and superimposed. An output signal dependent on the position or movement of the needle is derived from the beams. The optical probe is arranged in a hollow chamber, which is filled with air, fuel or a fuel-air mixture, in the casing of the injection system near the end of the needle.
• DE 4105270 Al entitled "Optical displacement or deformation measurement process and device" with a priority date of 20.02.1991 in which an optical device and related method for the measurement of a displacement or deformation is illustrated, and in which a light beam is emitted by a light emitter having a light output steady;
• EP 1925813 Bl entitled "Fuel injector with a measuring device" with priority date 30.10.2006 referring to a measuring device consisting of an inductive sensor provided with a measuring body which surrounds at least partially the needle sprayer; the measuring device comprises a coil body, embedded in a magnetic yoke, acting as the excitation coil and the sensor, the magnetic yoke being slotted radially and / or having a material with high electrical resistance such as composite powder or ferrite;
• EP 0078987 Bl entitled "Fuel injection detecting system for a diesel engine" with priority date 11.11.1981 relative to a fuel injection detecting system for diesel engines comprising: a lift sensor to generate a signal (SI) variable in function of the displacement of the shutter, and a comparator that allows comparing the voltage signal (SI) with a reference voltage (VREF) and generating a binary signal (S2) representing the comparison result;
• US 6359445 Bl entitled "Microwave sensor for Determining position for displacement of a movable part, such as a needle valve" with a priority date of 25.03.1997 which describes a microwave sensor that produces an electrical output signal according to a displacement of a movable mechanical part, especially a valve needle in an injector valve for injecting fuel into an internal combustion engine; the sensor is provided with a resonance chamber for microwaves of a predetermined frequency and an antenna for receiving the microwaves inside the chamber, in which protrudes the end of the movable mechanical part; the antenna is connected to a circuit which detects changes in the microwave radiation fed into the chamber according to the mechanical displacements of the mechanical part;
• WO 82/01069 Al entitled "Needle position sensing system for needle and poppet valve fuel injectors" with a priority date of 15.09.1980 relating to a system for detecting the position of the needle of an injector coupled within said injector and displaceable between open and closed positions by means of a spring positioned within a chamber and coupled to said needle; the detection system comprises: a passageway in said fuel injector for establishing communication with said chamber from a location external to said fuel injector, a magnetic sensor, a proximity detector, to detect displacements of said sensor, sized to move within said passage, and a sensor holder aligned with said passage for guiding said detector in a predetermined position with respect to said needle and to maintain said detector in a fixed position after said detection means are completely inserted inside said support means.
These systems, however, have several drawbacks.
The scientific literature (see M. Coppo, Dongiovanni C, Negri C, "A Linear optical sensor for measuring needle displacement in common-rail diesel injectors", Sensors and Actuators A 134/2 (2007) pp. 366-373, doi: 10.1016/j.sna.2006.05.038) shows that solutions based on electromagnetic systems require the adoption of shieldings, even though of limited effectiveness, and the need for accurate turning, finalized to the realization of a frusto-conical surface formed on the cylindrical body of the injector control piston, in correspondence of which the sensor is placed.
However, this processing generates a respectable notch effect, which greatly compromises the mechanical strength.
In any case, the cost for the achievement of these solutions, which runs to about one thousand Euro, prevents an extensive use for testing, as well as the serial application on-board and hence the real-time control of the operation of the injectors.
Moreover, some of the optical systems are very expensive as being based on laser light sources.
The operating principle proposed in document DE4105270A1 consists of coupling the movable or deformable object to the emitter or to the receiver or to an optical system consisting of a lens or a mirror; the reduction of light intensity is obtained by diverting the light beam or moving the receiver or the transmitter.
In particular, the operating principle proposed for the detection of the displacement of the control piston of an injector is based on a mirror mounted on the movable body and not on a shielding body coincident with the movable body. It should also be noted that said optical systems for the measurement of the displacement suffer from the contamination of the measuring ambient by the liquids normally present in the measuring volume or drawing through the imperfections of the seals.
The ineffectiveness and / or the high cost of the state of art technologies or of the proposals of the scientific community confirm the need for a more simple and economical transducer, which combines reliability and repeatability of measurements.
Purpose of the present invention is to solve said drawbacks through the realization of an optical system utilizing a transducer, or an optical sensor, operating in a sealed measuring chamber and self-cleaning that allows the control and diagnostics of the operation of any type injectors, also with gasoline feeding, as well as other mechanical components furniture drowned in a fluid.
The new optical system according to the here presented invention allows to reduce the high costs for the realization of the sensors currently used for this application and, at the same time, to solve the known problems of the existing electromagnetic devices, affected by the magnetic fields generated by coil of the same injector at the time of excitation of its solenoid valve.
In other words, the system for control and diagnostics of the operation of injectors for fuel injection systems, utilizing an optical sensor according to the present invention, provides for a remarkable cleaning of the signal transmitted to the electromagnetic devices, repeatability conditions and extremely low costs of realization.
The optical system according to the present invention ensures a reliable instantaneous measurement of the injector opening, making available a low cost tool for large scale testing of the injectors and the possibility to produce in series motors equipped with a control and real time diagnostic system for injectors.
The main advantages obtainable with the use of the optical system according to the present invention are therefore summarized as follows:
• reliability in relation to the quality of the results obtained;
9 components ready for the industrialization;
• extreme cost-effectiveness;
• ease of application with regard to changes to be made to the mechanical parts of the systems currently on the market;
• simplicity of the operation principle;
• flexibility in use for various applications.
A preferred embodiment of the optical system according to the present invention and its operation principle are described in the tables of the attached drawings which illustrate, respectively:
fig. 1 - a perspective exploded view, with parts partially cut away, of the main components of the optical system applied to an injector for common rail systems;
fig. 2 - a schematic view illustrating the optical access of the overlap of the through holes made respectively on the injector and on the control piston;
fig. 3 - a diagram illustrating the variation of the output signal emitted by the photoreceiver with the increase in the percentage of overlap between the three holes;
fig. 4 - a perspective view with parts partially removed of an injector provided with a seal and drainage system of fuel;
fig. 5 - an example of the experimental remarks relating to two consecutive injections of an injector provided with the optical system according to the invention.
The optical system for measuring displacement according to the present invention, illustrated in a preferred embodiment in figure 1 , comprises a at least one photodiode emitter 1 and at least one transistor photoreceiver 2, acting in the field of the infrared or any other light frequencies not interfering with other light sources, including the external source of light. The photoemitter 1 and the photoreceiver 2 are allocated in two spaced plate 5 of polycarbonate, or other transparent material, having two cylindrical pins 6 forced or fixed in any other way in two coaxial holes 3, approximate 4 mm diameter, made on the body of the injector 8.
Photoemitter 1 and photoreceiver 2 are forced into the holes 9 formed in the two plates 5 of polycarbonate, transparent to infrared (or other light frequency) beam, acting as support for the two optical devices, or alternatively, in other embodiments of the system, photoemitter and photoreceiver, may be allocated directly in the holes 3 formed on the body 8 of the injector.
The non-binding choice of polycarbonate is due to the fact that it is a material which can be easily crossed by beams of infrared light or other frequency, since it does not cause significant scattering phenomena, and therefore does not deteriorate the readability of the signal passing through it.
The operation principle of the system uses the photoemitter 1 for emitting an infrared or other light frequency beam that, passing through suitable holes 3 made on the body 8 of the injector and through a hole 4 on the control piston 7, reaches the photoreceiver 2, raising its saturation level.
The through hole 4 on the control piston 7, has a diameter of about 1.5 mm and, in standby mode (injector closed), the geometric center is about 1.7 mm from that of said two holes 3, on the injector body 8.
The intensity of the light signal received by the photoreceiver 2 depends on the reciprocal position between the hole drilled on the control piston 7 of the injector and the holes drilled on the body 3 of the injector 8 and it is therefore indicative of the displacement of the control piston.
The light signal, once reached the photoreceiver 2, is converted into a voltage signal that can be measured by any data acquisition system.
From a geometrical point of view, illustrated in figure 2, the operation principle is based on the percentage of juxtaposition of said three through-holes: two holes 3 drilled on the body 8 of the injector 3 and the hole 4 on the control piston 7.
The circumference C4, radius R4 (for example approximately 0.75 mm), indicates the hole 4 on the piston, whose alternative motion with respect to the circumference R3, radius C3 (for example approximately 2 mm), indicating one of the two coaxial holes 3 on the injector body 8, produces an output voltage by the photoreceiver 2 variable in function of the area A identified by the intersection between the two circumferences.
Then the photoreceiver provides an indicative voltage depending on the intensity of the light signal perceived due to the displacement of the control piston.
Due to the position where the holes were drilled, the maximum lift of the control piston corresponds to the minimum percentage of juxtaposition, and, consequently, the minimum voltage signal emitted by the photoreceiver.
It is possible to invert this trend by matching the maximum lift of the control piston with the largest percentage of overlap.
The diagram of figure 3 refers to the static tests performed on the system and shows the relationship between the signal emitted by the photo receiver and the percentage of juxtaposition between the two circumferences C3 and C4.
Furthermore, the relationship between the intersection area A between the aforementioned circumferences and the distance between their centers is approximately linear for a wide range.
In the standby mode of an injector, the distance between the center 04 of hole 4 practiced on the control piston 7 and the center 03 of the two holes 3 on the injector body 8 depends on the diameters of the holes, on the maximum measuring displacement and on and the demand for linearity of the system.
In the case of injectors for common rail systems, said distance, measured along the longitudinal axis of the injector or of the control piston, is about 1.7 mm.
The geometry illustrated in the preferred embodiment of the system according to the present invention, shows, between the standby mode and end mode of the injector displacement, an optimal signal variation of output voltage, indicative of the displacement.
The effectiveness of the measurement of the displacement of the control piston of an injector depends on the cleanliness of the ambient in which it is carried out.
However, the system here described operates in a zone of the injector that is affected by the presence of leakage from the sprayer and the coupling cylinder / piston of the control piston. This fuel fills the body of the injector and is drained at the top, through suitable pipes.
The presence in the measuring ambient of reflux fuel, rising in the injector in pressure close to atmospheric one, can compromise the passage of infrared light and gives rise to phenomena of signal reduction or even its complete cancellation._For this reason, it is necessary to isolate the volume inside which the light passes: the ambient is ensured sealed by means of an appropriate o-ring 9 (circular section shaped elastomer rings, used as mechanical gaskets or seals) forcing on the control piston 7 and the use of two additional holes 10 drilled superiorly and inferiorly to the measuring zone, to which are connected two tubes of elastomer (Rilsan ®) necessary to assure the drainage of the fuel (see figure 4).
To guarantee a greater tightness of the measuring ambient, it is fed with compressed air, or other gas, pressurized at about 1.5 ÷ 3 bar abs through a rail, not shown, equipped with a nonreturn valve and connected to the sealed chamber by means of a threaded quick coupling 1 1 screwed to the hole 12 drilled on the body 8 of the injector, thereby creating an air cushion confined by the t ^o o-ring 9.
In this way the measurement chamber remains totally cleaned and the measurement quality is always excellent.
The system has also self-cleaning autonomous ability, useful in the starting phase or in case of malfunction.
The experimental tests on the injectors provided of the optical system according to the invention, have confirmed the results of the static tests, proving the hypotheses on the geometry of the arrangement of the holes and validating the solutions adopted to stop the reflux fuel in the measurement ambient.
The optical system according to the present invention excels hence for reliability and repeatability without incurring in significant distortion problems of the signal representative of the displacement.
Figure 5 is an example of the experimental remark relating to two consecutive injections of an injector provided with the system according to the invention.
One of the advantages obtained with said system is certainly the quality of the result obtainable by means of components ready for the industrialization and extremely cost- effective.
The characteristics of this new system (low cost and reliability) may also make its use profitable for acceptance tests of the injectors before placing on the market and for real-time on board controls, and consequent industrial fall-out and interest of the major car manufacturers.
A source of compressed air whose pressure is totally compatible with that required by the system according to the invention, is already available in engines equipped with supercharging turbo-groups; the required flow to the system is instead absolutely negligible. Its simplicity is evident even with regard to changes that have to be made to the mechanics of the system currently on market.
These are mainly small or very small diameter holes, which introduce a negligible reduction of the structural features on the control piston.
The presence of the hole on the shaft could obviously be expected already in the design and implementation of the injectors.
The drainage system, finally, does not hinder the opening of the injector.
The geometric shape of the lights for the optical access could be trivially circular or other shape.
Other shapes may be specifically designed to extend the range of linearity of the result and then further improve the usability of the data.
Moreover, by means of a different arrangement of the components, the use of this optical system could also provide the application of the photodiodes housing in the notches on the piston, thus excluding the need for machining, although of reduced entity, to be done on the command rod and the injector body, with a further reduction in the time of implementation of the system.
This solution provides that, instead of the area identified by the circles indicating said holes, the variation of the voltage emitted by the receiver lead back to the alternation of the shadow area due to the presence of a notch on the piston with the transit of the infrared light, according to a dynamic similar to the system described herein.
It's useful to highlight that the simplicity of the operating principle implies that the margins of the use of this type of measurement system may possibly be extended to other applications in which, regardless of the components provided by them, there isn't the problem inherent in the presence of contaminant in the measuring ambient.
The optical system according to the invention illustrated in the figures is applied for the measurement of the displacement of the control piston of an injector for common rail systems; the system is, however, generally applicable, with appropriate modifications of the dimensions and the geometry and/or with a different arrangement of the components, for the measurement of the displacement of the control piston or shutter needle of any type injectors, even with gasoline feeding (direct injection), as well as other mechanical components furniture drowned in a fluid.

Claims

Claims
1. "Optical system for the measurement of the displacement of a movable body drowned in a fluid", comprising:
- a measuring environment with an almost watertight chamber,
- a fixed body, having at least two coaxial holes of any geometry,
- a movable body, having at least one through hole of any geometry,
- at least one diode for the emission of an infrared, or other light frequency beam, place in one of said coaxial holes drilled on the fixed body,
at least one photo receiver transistor for receiving said beam, positioned frontally to said diode, and placed in the second of said coaxial holes drilled on the fixed body, an electronic circuit for the transmission and reception of the light signal, characterized in that said infrared, or other light frequency beam, by passing through the coaxial holes on the fixed body and the through the hole on the movable body, reaches the photo receiver that produces an indicative voltage derived from the intensity of the received light signal which is due to the displacement of the movable body with respect to the fixed body, said voltage being proportional to the percentage of overlap between said through holes of the fixed body and said through hole of the movable body.
2. Optical system according to claim 1, aimed for the control and diagnostics of the operation of any injector, for common rail systems or other devices for direct injection, for internal combustion engines with any power supply, comprising:
a measuring environment with a watertight chamber,
the body (8) of an injector, provided with two coaxial holes (3),
a control piston (7), provided with a through hole (4), at least one photodiode emitter (1) for the emission of an infrared, or other light frequency beam, placed in one of said coaxial holes (3),
at least one photo receiver transistor (2) for the reception of said beam, placed in the second of said coaxial holes (3),
an electronic circuit for the transmission and reception of the light signal, characterized in that the infrared, or other light frequency beam, passing through the holes (3) on the body (8) of the injector and the through hole (4) on the control piston (7), reaches the photo receiver (2) which will produce an indicative voltage derived from the intensity of the received light signal, which is due to the displacement of the control piston (7) with respect to the body (8) of the injector, said voltage being proportional to the percentage of overlap between the through holes (3) drilled on the fixed body (8) of the injector and the through hole (4) drilled on the control piston (7).
3. Optical system according to claims 1 and 2 characterized in that the maximum displacement of the movable body with respect to the fixed body or the maximum lift of the control piston (7) with respect to the body (8) of the injector corresponds to the minimum, or alternatively to the maximum, percentage of overlap between said through holes, or at the minimum or alternatively the maximum width of the area (A) identified by the intersection between the circumferences of said holes, hence to the minimum or maximum signal emitted by the photo receiver.
4. Optical system according to the previous claims characterized in that the light signal, once reached the photo receiver, is converted into a voltage signal that can be measured by any data acquisition system.
5. Optical system according to the previous claims characterized in that the variation of the signal emitted by the photo receiver with the increasing of the percentage of overlap between the coaxial holes drilled on the fixed body / injector body and the through hole drilled on the movable body / control piston, is, for a wide range, almost linear.
6. Optical system according to the previous claims provided with at least two supports each consisting of a polycarbonate sheet, or other material transparent to infrared or other frequency radiation, equipped with a cylindrical pin forced or secured in any manner in one of the two coaxial holes of the fixed body and having the function of supporting the photodiodes, both emitter and receiver, said supports being able to ensure high standards of concentration of the infrared or other frequency beam.
7. Optical system according to claims 2 to 6 characterized in that the measuring environment is maintained watertight by the application of suitable o-rings (9) which have to be forced on the control piston (7) and that the drainage of the fluid is carried out by means of two elastomer tubes applied to two holes (10) drilled superiorly and inferiorly to the measurement zone, said o-rings (9) being interposed between the drainage holes (10) and the holes (3, 4) for the transit of the infrared signal.
8. Optical system according to claims 2 to 7 characterized in that the portion of residual reflux fluid, escaped from the action of the o-rings (9) and of the drainage pipes connected to the holes (10), is eliminated from the measuring environment by the introduction of compressed air, or other suitable gas, through a pipe connected to the watertight chamber by means of a fast connector (11) to be connected, by means of threaded coupling or other suitable system, to a hole (12) drilled on the body (8) of the injector, said fast connector (1 1) being provided with at least one retaining valve.
9. Optical system according to claims 2 to 8 applicable for measuring the displacement of the control piston or the nozzle needle of injectors of any type, with petrol supply, as well as other mechanical moving parts drowned in a fluid.
PCT/IB2013/000815 2012-10-19 2013-05-08 Optical system for the measurement of the displacement of a movable body drowned in a fluid WO2014060799A1 (en)

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IT000507A ITRM20120507A1 (en) 2012-10-19 2012-10-19 OPTICAL SYSTEM FOR THE MEASUREMENT OF THE MOVEMENT OF A MOBILE BODY DENIED IN A FLUIDO

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EP4194905A1 (en) * 2021-12-13 2023-06-14 AEA S.r.l. Device to measure the movement of a shutter of an injector

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