JP4567687B2 - Multi-capillary fuel injector for internal combustion engines - Google Patents

Abstract

A fuel injector for vaporizing a liquid fuel for use in an internal combustion engine. The fuel injector includes a plurality of capillary flow passages, each of the plurality of capillary flow passages having an inlet end and an outlet end; a heat source arranged along each of the plurality of capillary flow passages, the heat source operable to heat the liquid fuel in each of the plurality of capillary flow passages to a level sufficient to change at least a portion thereof from the liquid state to a vapor state and deliver a stream of substantially vaporized fuel from each outlet end of the plurality of capillary flow passages; and a valve for metering substantially vaporized fuel to the internal combustion engine, the valve located downstream of each outlet end of the plurality of capillary flow passages. The fuel injector is effective in reducing cold-start and warm-up emissions of an internal combustion engine.

Description

  The present invention relates to fuel delivery to an internal combustion engine.

Since the 1970s, port fuel injection engines have utilized three-way catalysts and closed-loop engine control to minimize NO _x , CO, and unburned hydrocarbon emissions. This measure has been found to be particularly effective during normal operation when the engine and exhaust components have reached a sufficient temperature. However, in order to achieve the desired conversion efficiency of NO _x , CO, and unburned hydrocarbons, the three-way catalyst must be higher than its inherent catalytic activation temperature.

  In addition, the engine must be at a temperature sufficient to allow the liquid fuel to evaporate when it collides with intake components such as the port wall and / or the back of the valve. The effectiveness of the process at which the engine is at a sufficient temperature is such that the process provides an appropriate degree of control over the stoichiometric composition of the fuel / air mixture, thereby allowing idle performance and three-way catalyst performance. And the process requires that the fuel supplied to the engine be burned during the combustion stroke, thereby not requiring sufficient fuel supply to compensate for liquid fuel that does not evaporate sufficiently and / or accumulates in the intake components. It is important in ensuring that it loses gender.

In order to perform chemical complete combustion, the fuel / air mixture must be evaporated to obtain a stoichiometric gas phase mixture. A stoichiometric combustible mixture contains the exact amount of air (oxygen) and fuel required for complete combustion. In the case of gasoline, this air / fuel ratio is about 14.7: 1 by weight. A fuel / air mixture that is not fully evaporated and / or contains fuel in excess of the stoichiometric amount will result in incomplete combustion and reduced thermal efficiency. The products of an ideal combustion process are water (H ₂ O) and carbon dioxide (CO ₂ ). If combustion is incomplete, some carbon will not be fully oxidized, resulting in carbon monoxide (CO) and unburned hydrocarbons (HC).

  Under cold start and warm conditions, the processes used to reduce exhaust emissions and deliver high quality fuel vapors do not function properly due to the relatively low temperature. In particular, the effectiveness of the three-way catalyst is not fully exhibited below about 250 ° C., and as a result, most of the unburned hydrocarbons are released into the environment without being converted. Under these conditions, the increase in hydrocarbon emissions will be exacerbated by the excessive fuel supply required during cold start and warm up. That is, fuel does not evaporate quickly upon collision with cold intake manifold components, so excessive fuel supply is required to produce a combustible mixture for engine start and acceptable idle characteristics. .

  As a result of mandates to reduce air pollution around the world, attempts have been made to compensate for combustion inefficiencies through various modifications to fuel systems and engines. As evidenced by prior art on fuel pre-treatment and delivery systems, many efforts have been made to reduce liquid fuel droplet size, improve system turbulence, and allow more complete combustion It has been directed to apply enough heat to evaporate the fuel.

  However, inefficient fuel pretreatment at low engine temperatures results in higher emissions, leaving the problem of requiring aftertreatment and complex control techniques. Such control methods include exhaust gas recirculation, variable valve timing, delayed ignition timing, compression ratio reduction, use of catalytic converters, and oxidation of unburned hydrocarbons to generate an exothermic reaction that is advantageous for the activation of catalytic converters. An air injection for doing this is mentioned.

  As noted above, in conventional engines, excessive fuel supply to the cold start and warm engine is a significant source of unburned hydrocarbon emissions. As much as 80% of the total hydrocarbon emissions generated by a typical modern port fuel injection (PFI) gasoline engine passenger car are supplied with excess fuel to the engine and a cold start and no catalytic converter is essentially operating It is estimated to occur during the warm-up period.

  This aspect of passenger car engine operation has become the focus of significant technological development efforts as a relatively large portion of unburned hydrocarbons is released during start-up. Furthermore, these development efforts will continue to be a top priority, as increasingly stringent emission standards are legislated and users are still cost and performance sensitive. Such efforts to reduce starting emissions in conventional engines are generally in two categories: 1) reducing the activation time of the three-way catalyst system and 2) evaporating the fuel. Classified as technology improvements. Efforts made so far to reduce the activation time of the three-way catalyst include delaying the ignition timing to raise the exhaust temperature, opening the exhaust valve early, electrically heating the catalyst, Heating with a burner or flame and heating the catalyst by catalysis are mentioned. Overall, these efforts are expensive and do not address HC emissions during and immediately after cold start.

  Various techniques have been proposed to address the problem of fuel evaporation. U.S. Pat. Nos. 5,195,477 issued to Hudson, Jr et al., U.S. Pat. No. 5,331,937 issued to Clarke as U.S. patents proposing fuel evaporation techniques. No. 4, U.S. Pat. No. 4,886,032 issued to Asmus, U.S. Pat. No. 4,955,351 issued to Lewis et al., U.S. Pat. No. issued to Oza No. 4,458,655, US Pat. No. 6,189,518 issued to Cooke, US Pat. No. 5,482,023 issued to Hunt, issued to Hunt US Pat. No. 6,109,247, US Pat. No. 6,067,970 issued to Awarzamani et al., US Pat. No. 5,947,091 issued to Krohn et al., Nines (Nines) Issued US Pat. No. 5,758,826, US Pat. No. 5,836,289 issued to Thring, and US Pat. No. 5 issued to Cikanek, Jr et al. , 813,388.

Another proposed fuel delivery device is US Pat. No. 3,716,416 which discloses a fuel throttle device for use in a fuel cell system. This fuel cell system is intended to self-adjust and generate a predetermined level of power. The proposed fuel throttling system includes a capillary flow control device that does not improve fuel pretreatment for subsequent combustion, but fuel flow in response to the fuel cell power output. It is a device for narrowing down. Rather, the fuel, for conversion to H _2, is fed to the fuel reformer and then is adapted to be fed to the fuel cell. In a preferred embodiment, the capillary tube is made of metal and the capillary itself is used as a resistor that makes electrical contact with the power output of the fuel cell. Since the vapor flow resistance is greater than the liquid flow resistance, the vapor flow will be throttled as the power output increases. Fuels that are recommended to be used include any fluid that is easily converted from a liquid phase to a vapor phase by the application of heat and flows freely within the capillary. Evaporation appears to be done in such a way that vapor lock occurs in the car engine.

  US Pat. No. 6,276,347 proposes a supercritical or near supercritical atomizer and a method for achieving liquid atomization or evaporation. The supercritical atomizer of US Pat. No. 6,276,347 can use heavy fuel to ignite a small, lightweight, low compression ratio spark ignition piston engine that typically burns gasoline. It is stated. This atomizer moves liquid or liquid fuels towards their supercritical temperature, releases the fuel into the low pressure region of the gas stable zone in the phase equilibrium diagram associated with the fuel, and finely sprays or evaporates the fuel The aim is to produce fine droplet sprays from these fuels. Utility for applications such as combustion engines, scientific equipment, chemical processing, waste treatment control, cleaning, etching, insect control, surface modification, humidification, and evaporation are disclosed.

In order to minimize fuel alteration, US Pat. No. 6,276,347 maintains the fuel at a temperature below the supercritical temperature until it passes through the distal end of the atomizing throttle valve. ,is suggesting. In some applications, it is desirable to heat only the throttle valve tip to minimize the possibility of chemical reactants or precipitation. This is stated to reduce problems associated with impurities, reactants, or materials in the fuel stream that tend to become detached from the solution and plug lines and filters. Operation at supercritical or near supercritical pressures suggests that the fuel delivery system is operated within the range of 21 kg / cm ² (300 psi) to 56 kg / cm ² (800 psi). The use of supercritical pressure and supercritical temperature may reduce atomizer blockage but requires the use of relatively expensive fuel pumps and fuel lines and fittings that allow operation at these high pressures. There seems to be.

  Despite these and other developments in the art, pressure drop within acceptable range across the injector, evaporative fuel flow rate within acceptable range at 100% duty cycle, acceptable range at 100% duty cycle Meet critical design requirements such as the flow rate of liquid fuel within, result in minimum heating time, meet minimum power requirements, and show a linear relationship between duty cycle and evaporated fuel flow, There is a need for an injector design that exhibits a linear relationship with the liquid fuel flow and that can provide improved evaporation.

In one aspect, a fuel injector for evaporating liquid fuel used in an internal combustion engine is provided. This fuel injector
(A) a plurality of capillary channels, each of which has an inlet end and an outlet end;
(B) a heat source disposed along each of the plurality of capillary channels, wherein at least part of the liquid fuel in each of the plurality of capillary channels is changed from a liquid state to a vapor state, A heat source operable to heat the vaporized fuel stream to a level sufficient to be delivered from each of the outlet ends of the plurality of capillary channels;
(C) a valve for metering and delivering substantially evaporated fuel to the internal combustion engine, the valve being disposed downstream of each of the outlet ends of the plurality of capillary channels. .

In another aspect, a method for delivering evaporated fuel to an internal combustion engine is provided. This method
(A) supplying liquid fuel to a plurality of capillary channels of a fuel injector;
(B) heating the liquid fuel in the plurality of capillary channels of the fuel injector and passing the evaporated fuel through the outlets of the plurality of capillary channels;
(C) metering the evaporated fuel into a combustion chamber of the internal combustion engine through a valve disposed downstream of each outlet of the plurality of capillary channels.

  The provided fuel injector is beneficial for reducing cold start and warm-up emissions of internal combustion engines. Efficient combustion will be facilitated by forming a fine droplet size aerosol when the substantially evaporated fuel condenses in the air. Substantially evaporated fuel is supplied directly or indirectly to the combustion chamber of the internal combustion engine during cold engine start-up and warm-up or other periods of engine operation, and this improved mixture adjustment Capacities will achieve emissions reduction during cold start, warm-up, and transition operations.

  The capillary channel can be formed in a capillary tube. A heat source includes a resistive heating element or a portion of a tube that is heated by passing an electric current. The fuel source can be arranged to deliver pressurized or non-pressurized liquid fuel to the flow path. The fuel injector can provide vaporized fuel that will mix with the air and form an aerosol having an average droplet size of 25 μm or less.

  Hereinafter, the present invention will be described in more detail based on preferred embodiments of the present invention and with reference to the accompanying drawings.

  FIG. 1 illustrates, in partial cross-section, a multi-capillary fuel injector having an electronically heated capillary bundle disposed upstream of a solenoid operated fuel throttle valve, according to a preferred embodiment.

  FIG. 2 shows an enlarged view of the capillary bundle of the embodiment of FIG.

  FIG. 3A shows a plan view of a preferred form of the diaphragm plate 40.

  FIG. 3B shows a cross-sectional view along line 3B-3B of FIG. 3A.

  FIG. 4A shows a plan view of a preferred form of orifice plate.

  FIG. 4B shows a cross-sectional view along line 4B-4B of FIG. 4A.

  FIG. 5A shows the cooperating state of the throttle plate of FIG. 3B and the orifice plate of FIG. 4B when placed in the open position to form a fuel flow path.

  FIG. 5B shows the cooperating state of the throttle plate of FIG. 3B and the orifice plate of FIG. 4B when placed in the closed position so as to block the fuel flow path.

  FIG. 6 is an isometric view of another multi-capillary fuel injector having an electronically heated capillary bundle located upstream of a solenoid operated fuel throttle valve, according to another preferred form of injector. Is shown.

  FIG. 7 is a partial cross-sectional side view of the multi-capillary fuel injector of FIG.

  FIG. 8 is a chart showing the trade-off (compatibility) between minimizing the power supplied to the injector and minimizing the rise time associated with the injector for different heating masses.

  FIG. 9 is a chart showing that emissions are maximally reduced by injecting steam only during the period when the intake valve of the engine cycle is open.

  FIG. 10 is a schematic diagram of a fuel delivery and control system according to a preferred embodiment.

  FIG. 11 shows the liquid mass flow rate and the vapor mass flow rate of fuel through a single 3.8 cm (1.5 inch) capillary as a function of capillary pressure drop.

  FIG. 12 shows the fuel droplet size (SMD, μm) in a 3.8 cm (1.5 inch) thin wall capillary as a function of resistance set point.

  The embodiment shown in FIGS. 1 to 12 will be described below. Like numbers refer to like parts throughout.

  Provided herein are a multi-capillary fuel injector having a throttle valve that is useful for cold start, warm-up, and normal operation of an internal combustion engine and a fuel system using the same. The fuel system includes a fuel injector having a plurality of capillary channels, each capillary channel capable of heating a liquid fuel such that substantially evaporated fuel is supplied when desired. Substantially evaporated fuel can be combusted with reduced emissions compared to conventional fuel injector systems. The fuel delivery system of the present invention requires less power and shortens the rise time than other evaporation techniques.

  The injector design provided herein includes an acceptable pressure drop across the injector body, an evaporated fuel flow rate within 100% duty cycle, and a 100% duty cycle. Liquid fuel flow rate, minimum heating time, minimum power requirement, linear relationship between duty cycle and evaporated fuel flow, and linear relationship between duty cycle and liquid fuel flow It is aimed at meeting the design requirements of several automotive fuel injectors.

  As is well known, gasoline does not evaporate easily at low temperatures. During cold start-up and warm-up periods of automotive engines, liquid fuel evaporates only in relatively small amounts. It is therefore necessary to supply excess liquid fuel to each cylinder of the engine in order to obtain a burning air / fuel mixture. When igniting the fuel vapor resulting from excess liquid fuel, the combustion gases released from the cylinder will contain unburned fuel and undesirable gaseous emissions. However, once the normal operating temperature is reached, the liquid fuel evaporates easily, so that less fuel is required to obtain an easily combusted air / fuel mixture. Advantageously, when the normal operating temperature is reached, the air / fuel mixture may be controlled at or near the stoichiometric ratio, thereby reducing unburned hydrocarbon and carbon monoxide emissions. It will be. In addition, when the fuel supply is controlled at or near the stoichiometric ratio, a three-way catalyst (TWC) system can simultaneously oxidize unburned hydrocarbons and carbon monoxide and reduce nitrogen oxides. Just enough air will be obtained from the exhaust stream.

  The fuel injectors and fuel systems disclosed herein inject substantially vaporized fuel into the intake passage or directly into the engine cylinder, thereby causing excess during engine start-up and warm-up periods. The need to supply more fuel is eliminated. The fuel is preferably delivered to the engine in the form of a stoichiometric or fuel-lean mixture with air or air and diluent so that substantially all of the fuel is cold-started and warm-up. It will be burned during the period.

  In the case of conventional port fuel injection, an excessive fuel supply is required to ensure a powerful and rapid engine start. In a fuel-rich state, the exhaust stream reaching the three-way catalyst does not contain enough oxygen to oxidize excess fuel and unburned hydrocarbons when the catalyst is activated. One approach to addressing this problem is to utilize an air pump to supply additional air to the exhaust stream upstream of the catalytic converter. The purpose is to produce a stoichiometric or slightly fuel lean exhaust stream that can react with the catalyst surface when the catalyst reaches its activation temperature. In contrast, according to the system and method of the present invention, the engine can be operated stoichiometrically or with very little fuel lean during cold start and warm-up periods, resulting in excessive fuel supply. Both the need and the need for an additional exhaust air pump can be eliminated, reducing the cost and complexity of the exhaust aftertreatment system.

  As previously mentioned, during the cold start and warm-up periods, the three way catalyst is initially at a low temperature and is unable to reduce most of the unburned hydrocarbons passing through the catalyst. Much effort has been devoted to reducing the activation time of the three-way catalyst and converting most of the unburned hydrocarbons released during cold start and warm-up periods. One such concept is a method of intentionally operating the engine with very rich fuel during cold start and warm-up periods. By using an exhaust air pump that supplies air into this fuel-rich exhaust stream, a combustible mixture is produced that is combusted by auto-ignition or by an ignition source upstream of or in the catalytic converter. . The heat generated by this oxidation process heats the exhaust gas significantly, and this heat is mostly transferred to the catalytic converter as it passes through the catalyst. By using the system and method of the present invention, the engine is controlled to operate multiple cylinders alternately in fuel rich and fuel lean conditions, thereby achieving the same effect without the need for an air pump. Can be achieved. For example, in the case of a 4-cylinder engine, the two cylinders will be operated in a fuel rich state that produces unburned hydrocarbons in the exhaust during cold start and warm up periods. The remaining two cylinders will be operated in a fuel lean condition that provides oxygen in the exhaust stream during cold start and warm up periods.

  The system and method of the present invention may be utilized with a gasoline direct injection engine (GDI). In a GDI engine, fuel is injected directly into the cylinder as a fine spray stream that evaporates and mixes with air, and prior to ignition, premixes the air with the evaporated fuel. It comes to form. Current GDI engines require high fuel pressure to spray the fuel stream. GDI engines are designed to perform stratified charge with partial loads to reduce the pump loss inherent in conventional indirect injection engines. A spark ignition engine with stratified charge has the potential to improve fuel economy and reduce emissions by burning a lean mixture. Preferably, the entire lean mixture is formed in the combustion chamber and is controlled to be stoichiometric or slightly fuel rich in the vicinity of the spark plug upon ignition. Thus, the stoichiometric part is easily ignited, which will ignite the remaining lean mixture. Although pump losses will be reduced, at present, the operating range that can be achieved by stratified charge is limited to low engine speeds and relatively low engine loads. Limiting factors include insufficient time for evaporation and mixing at high engine speeds and poor mixing or poor air utilization at high loads. By supplying evaporated fuel, the system and method of the present invention extends the operating range for stratified charge operation and eliminates problems associated with insufficient time required for evaporation and mixing. Can do. Advantageously, unlike conventional GDI fuel systems, the fuel pressure used in the practice of the present invention can be reduced, thereby reducing the overall cost and complexity of the fuel system.

  The present invention relates to a fuel delivery device for an internal combustion engine, a pressurized liquid fuel source for supplying liquid fuel under pressure, a plurality of capillary channels connected to the liquid fuel source, and a plurality of capillary channels And a heat supply device arranged along the line. The heat source is operable to heat the liquid fuel in the at least one capillary channel sufficiently to deliver a substantially evaporated fuel flow. The fuel delivery device is preferably operated to deliver the vaporized fuel flow to one or more combustion chambers of the internal combustion engine during startup, warm-up, and other operating conditions of the internal combustion engine. It is like that. If necessary, liquid fuel can be delivered to the engine under normal operating conditions using a plurality of capillary channels.

  The present invention is also a method for supplying fuel to an internal combustion engine, the step of supplying pressurized liquid fuel to a plurality of capillary channels, and the pressurized liquid fuel in the plurality of capillary channels. Heating the vaporized fuel stream sufficiently to be delivered to at least one combustion chamber of the internal combustion engine during startup, warm-up, and other operating conditions of the internal combustion engine. ing.

The fuel delivery system according to the present invention includes a plurality of capillary sized flow paths through which pressurized fuel passes before being injected into the engine for combustion. The capillary sized flow path may preferably comprise a hydraulic diameter of less than 2 mm, more preferably less than 1 mm, and most preferably less than 0.75 mm. The hydraulic diameter is used to calculate the fluid flow through the fluid transport element. The hydraulic radius is defined as the flow area of the fluid transport element divided by the perimeter of the solid boundary in contact with the fluid (commonly referred to as the wet edge). If fluid transport elements of circular cross-section, when the element is filled with the flow, hydraulic radius is ^{(πD 2/4) / πD} = D / 4. For fluid flow in non-circular fluid transport elements, hydraulic diameter is used. From the definition of hydraulic radius, the diameter of a fluid transport element having a circular cross section is four times its hydraulic radius. Accordingly, the hydraulic diameter is defined as four times the hydraulic radius.

  As heat is applied along the capillary passage, at least a portion of the liquid fuel entering the flow passage will be converted to vapor as it travels along the passage. The fuel exits the capillary channel as a vapor, which optionally contains a small proportion of heated liquid fuel that has not been evaporated. The term “substantially evaporated” means that at least 50%, more preferably at least 70%, and most preferably at least 80% of the volume of liquid fuel is evaporated by a heat source. . Although 100% evaporation may be difficult to achieve due to complex physical effects, nevertheless complete evaporation is desirable. These complex physical effects include fluctuations in the boiling point of the fuel. This is because the boiling point depends on the pressure, which can change in the capillary channel. Thus, most of the fuel will reach the boiling point during heating in the capillary channel, but some of the liquid fuel may not be heated enough to evaporate completely, As a result, a part of the liquid fuel passes through the outlet of the capillary channel together with the evaporated fluid.

Each capillary size channel is preferably formed in a capillary body, such as a single or multi-layer metal, ceramic, or glass body. Each flow path has a closed volume that opens to the inlet and outlet, either or both of the inlet and outlet may be open to the exterior of the capillary body, or the same or other capillaries. It may be connected to other passages or connectors in the body. The heater can be formed using a portion of a capillary body, for example, a stainless steel tube or a portion of an Inconel tube, or as a separate layer or wire of resistive heating material incorporated in or on the capillary body. It can also be configured. Each channel may be of any shape with a closed volume that opens to the inlet and outlet and allows fluid to pass through. Each flow path may have any desired cross section, and preferably a circular cross section having a uniform diameter. Other capillary channel cross sections include non-circular shapes such as triangles, squares, rectangles, ellipses, or other shapes, and the cross sections of the channels need not be uniform. When the capillary channel is defined by a metal capillary tube, each tube may have an inner diameter of 0.01 to 3 mm, preferably 0.1 to 1 mm, most preferably 0.3 to 0.75 mm. it can. Alternatively, the capillary channel can also be defined by the cross-sectional area of the channel, which has a cross-sectional area of 8 × 10 ⁻⁵ to 7 × 10 ⁻⁵ m ² , preferably 8 × 10 ⁻³ to 8 × 10 ⁻¹ mm ² , more preferably 7 × 10 ⁻² to 4.5 × 10 ⁻¹ mm ² . Many combinations of multiple capillaries, different pressures, different capillary lengths, the amount of heat applied to the capillaries, and different cross-sectional areas are designed to suit a given application.

The liquid fuel can be supplied to the capillary channel under a pressure of at least 0.7 kg / cm ² (10 psi), preferably at least 1.4 kg / cm ² (20 psi). Each capillary channel has an inner diameter of approximately 0.051 cm (0.020 inch) to 0.076 cm (0.030 inch) and a length of approximately 2.54 cm (1 inch) to 7.62 cm (3 inches). To achieve the mass flow (approximately 100-200 mg / sec) required for stoichiometric start-up of typical sized automotive engine cylinders when defined by the interior of a stainless steel tube or Inconel tube the fuel will preferably be fed to the capillary channel at a pressure of less than 7kg / cm ² (100psi). In the case of two to four capillary passages of the type described herein, a substantially vaporized fuel flow sufficient to ensure a stoichiometric or near stoichiometric mixture of fuel and air is obtained. Can be supplied. Each capillary tube is characterized by having a low thermal inertia, whereby each capillary passage is very quickly, preferably within 2.0 seconds, more preferably within 0.5 seconds, most preferably 0. It is important that it can be raised to the desired temperature to evaporate the fuel within 1 second. This is beneficial in applications involving cold start of the engine. Low thermal inertia can also provide the advantage of improving fuel delivery responsiveness to, for example, sudden changes in engine power requirements during normal engine operation.

  In order to meter fuel through the low thermal inertia capillary channel described herein, an effective valve device is needed to regulate the flow of vapor from the distal end of the fuel injector. The thermal mass of the capillary channel intended here is small, so the valve device used to regulate the steam flow was heated to a minimum thermal mass so that the rise time and effectiveness were not degraded. It must be designed not to add to the system. Similarly, the surface area wetted by the fuel must be as small as possible so that the evaporated fuel does not recondense upon contact and degrade performance.

  Each of the preferred forms described below has the ability to enable fuel vapor pulsing and switch to liquid fuel injection. In each of the forms described herein, the vapor flow path in the capillary channel is actively heated so that the working fluid is in the vapor phase when in contact with the valve. The valve itself is preferably not actively heated.

  FIG. 1 shows one embodiment of a fuel injector 10 for evaporating liquid fuel drawn from a liquid fuel source F. FIG. A capillary bundle 15 is shown having a plurality of capillary channels 12, each having an inlet end 14 and an outlet end 16, the inlet end 14 being a liquid in a substantially liquid state. A fluid fuel source F is in fluid communication for directing fuel to the capillary channel 12.

  Preferably, the low mass plate valve assembly 18 is actuated by a solenoid 28. The solenoid 28 has a coil winding 32 connected to an electrical connector (not shown). When the coil winding 32 is excited, a magnetic field is guided into the diaphragm plate 40, thereby lifting the diaphragm plate 40. When electricity to the coil winding 32 is cut off, a spring (not shown) returns the diaphragm plate 40 to its original position.

  In an alternative embodiment, a solenoid element (not shown) is drawn into the center of the coil winding 32 to lift the diaphragm plate 40 connected to the solenoid element. The movement of the solenoid element caused by applying electricity to the coil winding 32 pulls the throttle plate 40 away from the orifice plate 42, allowing fuel to flow out (see FIG. 5A). Again, when electricity to the coil winding 32 is interrupted, a spring (not shown) will return the diaphragm plate 40 to its original position.

  A heat source 20 is disposed along each capillary channel 12. Most preferably, each heat source 20 forms a capillary channel 12 from a tube of electrically resistive material, and a portion of each capillary channel 12 when a current source is connected to the tube to deliver current. Is obtained by forming a heater element. As a result, each heat source 20, as can be seen, changes the liquid fuel in each capillary channel 12 from at least a portion from a liquid state to a vapor state, and a substantially evaporated fuel flow to each It is operable to heat to a level sufficient to feed from the outlet end 16 of the capillary channel 12. As can be appreciated, this method of delivering steam into the body of the injector minimizes the volume of material in contact with the vaporized fuel and thus heats to prevent premature condensation of the steam. The thermal mass that must be done is also kept to a minimum.

  Preferably, the capillary bundle 15 has an outer diameter (OD) of 0.081 inches and an inner diameter (ID) of 0.028 to 0.029 inches. It is good to consist of ˜4 thin-walled capillary channels 12. The capillary channels 12 are each composed of a stainless steel or annealed Inconel 600 tube having a heated length 20 of about 1.25 inches to about 2.50 inches. Good. When current is supplied to the capillary bundle 15, the heating source 20 of each capillary channel 12 becomes hot and then vaporizes the fuel as it flows through the capillary channel 12.

  Upon exiting the outlet end 16 of the capillary channel 12, the fuel flow is directed to the throttle 50 of the fuel injector 10. As described above, the throttle unit 50 is composed of a throttle valve that is actuated by a solenoid as in the conventional fuel injector. In this embodiment, the throttle plate as a moving member that opens and closes the flow path in the orifice plate 42. 40 is a flat plate type. The operation of the solenoid 28 that moves the throttle plate 40 between the open position and the closed position serves to meter and adjust the flow rate of the fuel exiting the injector 10.

  Upon exiting the restrictor plate 40, fuel will flow through the orifice plate. In the case of liquid fuel injection, the orifice plate 42 functions to provide the desired atomization and atomization of the spray. As shown in FIG. 1, a chimney 60 is provided to further direct the outgoing fuel flow and to allow the injector 10 to meet the full length requirements of a conventional port fuel injector. Is provided.

  The electrical connection is made by casting four spade-type connections into the bobbin 30. Two of the connecting parts function to supply power to the solenoid 28. The other connection is attached to the upper part of the capillary bundle 15. The last connection is embedded in the bobbin and terminates at the bottom of the bobbin 30 so that a connection with the distal end of the capillary bundle 15 is obtained.

  FIG. 2 is an enlarged view of the capillary bundle 15 of the embodiment of FIG. As shown, the capillary channel 12 is held in place by a spindle piece 26. The spindle piece 26 may have any of several geometric shapes as long as it structurally supports the capillary channel 12 without providing additional thermal inertia to the capillary channel 12. This spindle piece 26 may also function as part of an electrical path used to supply power to the heater formed by the heating length 20 of the capillary channel 12. As shown, the spindle piece 26 includes a spindle end 38 that is positioned to engage the outlet end 16 of the capillary channel 12 of the capillary bundle 15.

  Various methods of attaching the capillary bundle 15 to the area of the throttle unit 50 are conceivable. One method is performed using laser welding. Specifically, the capillary channel 12 is laser welded to the fixed disk through the thickness of the disk. This fixed disk will then be welded to the inner diameter of a passage extending downwardly along the centerline of the injector 10. As can be appreciated, the capillary channel 12 is secured in place by this welding process. This attachment method does not thermally isolate the capillary from the metal portion of the injector 10, but the flow path is relatively small (ie, the connection point between the stationary disk and the centerline passage is small), so that the thermal mass produced The increase is not expected to have a significant impact. However, it should be understood that a thermally insulating material may be used to hold the stationary disk in place.

  Another method of attaching the capillary bundle 15 to the area of the throttle 50 is performed using a brazing technique. According to this technique, the outlet end 16 of the capillary channel 12 is secured in place using a cup / disk device. The cup portion of the assembly is made of a metal short cylindrical piece, and the outlet end 16 of the capillary channel 12 is fitted therein. The end of the capillary passage will then be brazed to the inner diameter of the cup. The end of the cup closest to the throttle unit 50 is extended outward so as to be orthogonal to the axis of the cylinder. This cup portion is then brazed to the inner diameter of a separate disk. In order to ensure that there is no fluid path between the disk and the fuel injector housing, a method of separating them is used. Some examples of such methods include providing a physical connection between the disk and the fuel injector housing using soft welds or O-rings. The non-magnetic nature of brazing, the magnetic nature of the cup and disk, and the placement and thickness of each piece in this assembly are designed to act as part of the magnetic circuit of the fuel injector 10 Should be noted.

  FIG. 3A is a plan view of a preferred embodiment of the diaphragm plate 40. As shown, the throttle plate 40 includes a plurality of throttle openings 44 that allow fuel flow to pass from the outlet end 16 of the capillary channel 12 of the capillary bundle 15. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A. As shown in the drawing, the throttle plate 40 functions as a moving member that opens and closes a fuel flow path through the orifice plate 42 as described below.

  FIG. 4A is a plan view of a preferred embodiment of the orifice plate 42. As shown, the orifice plate 42 prevents fuel flow from the outlet end 16 of the capillary channel 12 of the capillary bundle 15 when the orifice plate 42 is in sealing engagement with the restrictor plate 40. For this purpose, an inner seal ring 46 and an outer landing ring 48 are provided. As shown in the figure, the orifice plate 42 functions as a fixed member that cooperates with the diaphragm plate 40 that functions as a moving member that opens and closes the flow path in the orifice plate 42. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A.

  FIG. 5A shows the state of the cooperative action of the throttle plate 40 and the orifice plate 42 when arranged in the open position so as to form a flow path for fuel flowing in the capillary bundle 15. FIG. 5B shows the cooperating state of the throttle plate 40 and the orientation plate 42 when they are arranged in the closed position so as to block the flow of fuel from the capillary bundle 15.

  6 and 7, another embodiment of a fuel injector 100 for evaporating liquid is shown. The fuel injector 100 has an inlet 190 and an outlet 192, which are advantageously conventional interchangeable so that they are substantially interchangeable with conventional port fuel injectors. It may be designed in the same way as in a port fuel injector. Particularly preferably, this embodiment has a ball-in-cone valve assembly 144. Similar to the format shown in FIG. 2, the capillary bundle 115 can be placed in the central hole 170.

  A capillary bundle 115 is shown having a plurality of capillary channels 112, each of which has an inlet end 114 and an outlet end 116, which is in fluid communication with the liquid fuel source F. ing. A heat source 120 is disposed along each capillary channel 112. Most preferably, each heat source 120 forms the capillary channel 112 from a tube of electrically resistive material and when the current source is connected to the tube electrical connections 122 and 124 to deliver the current. A portion of each capillary channel 112 is obtained by forming a heater element. As a result, each heater source 120, as can be seen, changes the liquid fuel in each capillary channel 112 from at least a portion of the liquid state to the vapor state and causes the vaporized fuel flow to vary substantially. It is operable to heat to a level sufficient to deliver from the outlet end 116 of the capillary channel 112. Again, this method of delivering steam to the body of the injector minimizes the surface area of the material in contact with the evaporated fuel, and thus heat that must be heated to prevent premature condensation of the steam. The mass will also be kept to a minimum.

  As in the embodiment of FIG. 1, the capillary bundle 115 has an outer diameter (OD) of 0.081 cm (0.032 inches) and a 0.071 to 0.074 cm (0.028 to 0.029 inch). 2 to 4 thin-walled capillary channels 112 having the same inner diameter (ID). The capillary channels 112 are each composed of a stainless steel or annealed Inconel 600 tube having a heated length 20 of about 1.25 inches to about 2.50 inches. Good. When current is supplied to the capillary channel 115, the heat source 120 of each capillary channel 112 heats up and then evaporates as the fuel flows through the capillary channel 112.

  One method that has utility for attaching the capillary bundle 115 to the area of the ball-in-cone valve assembly 144 is performed using laser welding. Specifically, the capillary channel 112 is laser welded to a fixed disk through the thickness of the disk. This fixed disk is then welded to the inner diameter of a center hole 170 that extends downward along the centerline of the injector 100. As can be appreciated, the capillary channel 112 is secured in place by this welding process. Again, this attachment method does not thermally isolate the capillaries from the metal portion of the injector 100, but because the flow path is relatively small (ie, the connection point between the fixed disk and the centerline passage is small). The resulting increase in thermal mass is not considered to have a significant effect. However, it should be understood that a thermally insulating material may be used to hold the stationary disk in place.

  Similar to the embodiment of FIGS. 1-5, brazing techniques may be used to attach the capillary bundle 115 to the area of the ball-in-cone valve assembly 144. According to this technique, a cup / disk device is used to secure the outlet end 116 of the capillary channel 112 in place. The cup portion of this assembly is made of a metal short cylindrical piece into which the outlet end 116 of the capillary channel 112 is fitted. The end of the capillary channel will then be brazed to the inner diameter of the cup. The end of the cup closest to the ball-in-cone valve assembly 144 is extended outward so as to be orthogonal to the axis of the cylinder. This cup portion is then brazed to the inner diameter of a separate disk. In order to ensure that there is no fluid path between the disk and the fuel injector housing 180, a method of separating them is used. Some examples of such methods include providing a physical connection between the disk and the fuel injector housing 180 using soft welds or O-rings. The non-magnetic nature of brazing, the magnetic nature of the cup and disk, and the placement and thickness of each piece in this assembly are designed to act as part of the magnetic circuit of the fuel injector 100, It should be noted.

  Referring to FIG. 7, the low mass ball valve assembly 144 is actuated by a solenoid 128. Solenoid 128 has a coil winding 132 connected to an electrical connector 176. When the coil winding 132 is energized, a magnetic field is directed into the plate 146 connected to the ball 140, thereby lifting the ball 140 from the conical seal surface 142, exposing the orifice 152, and allowing fuel to flow. I have to. When electricity from the coil winding 132 is interrupted, a spring (not shown) will return the plate 146 and the ball 140 attached thereto to their original position.

  In an alternative embodiment, a solenoid element (not shown) is drawn into the center of the coil winding 132 to lift the ball 140 connected to the solenoid element. The movement of the solenoid element caused by the application of electricity to the coil winding 132 pulls the ball 140 away from the conical seal surface 142, exposing the orifice 152 and allowing fuel to flow. Again, when electricity to the coil winding 132 is interrupted, a spring (not shown) will return the ball 140 to its original position.

  The spring is dimensioned so that the spring force pressing the ball against the cone at the outlet of the injector is sufficient to block the flow of pressurized liquid fuel in the injector.

  Still referring to FIG. 7, upon exiting the outlet end 116 of the capillary channel 112, the fuel flow will be directed to the ball-in-valve assembly 144 of the fuel injector 100. The throttle 150 is composed of a ball-in-conical throttle valve assembly 144 operated by a solenoid, like a conventional fuel injector. Actuation of a solenoid 128 that moves the plate 146 and ball 140 assembly between an open position and a closed position serves to meter the fuel flow rate out of the injector 100. Upon exiting the orifice 152, the fuel flows through the conical chimney 160 to provide the desired spray granulation and spray angulation. The cone angle can range over a wide range as long as the ball forms a seal with the conical surface. The chimney 160 also serves to allow the injector 100 to meet the overall length requirements of a conventional port fuel injector. As can be appreciated, proper operation of the injector 100 is possible without the chimney 160 being provided.

  As can be appreciated, the ball-in-cone valve assembly 140 allows the vaporized fuel flow to be metered by a restriction 150 having low thermal inertia and minimal wet area. These features are useful to ensure that vaporized fuel delivery is achieved with minimal time delay after initial power input. These features have also been found to mitigate pre-condensation of fuel vapor as it exits injector 100. This ensures that a minimum droplet size is obtained during steady state operation of the injector 100 when operated in fuel evaporation mode. Nevertheless, it is readily understood that the ball-in-cone valve assembly 140 shown in FIG. 6 is one of several valve designs that can be used in the injector design of the present invention. Should. An important feature of a suitable valve design used to meter fuel vapor is a combination of low thermal inertia and minimum wet area. Other suitable valve designs having these important features are disclosed in US patent application Ser. No. 10 / 342,267, filed Jan. 15, 2003. This disclosure is hereby incorporated by reference in its entirety.

  With further reference to FIG. 7, the electrical circuit used to supply heat to the capillary channel 112 includes a power source (not shown) and controller 2050 (see FIG. 10), a capillary bundle 115, and a capillary channel. It consists of a spade connection 174 attached to the capillary bundle 115 to allow resistance heating of 112 heating sections 120. In a preferred embodiment, the capillary bundle 115 includes a bus adjacent to the inlet end 114 of the capillary channel 112 and an outlet end 116 of the capillary channel 112 such that the entire capillary bundle 115 forms a single conductor unit. And another bus in the vicinity. The electrical connection is made by casting four spade shaped connections 174 and 176 into the bobbin 130. Two connections at the feed end of the bobbin 130 function to supply power to the solenoid 128. The other connection at the inlet end of the bobbin 130 is attached to the inlet end of the capillary bundle 115. The fourth electrical connection is embedded in the bobbin 130 and terminates at the distal end of the bobbin 130 for electrical connection with the outlet end 116 of the capillary bundle 115.

  To achieve evaporation in a cold engine environment, there is a trade-off (compatibility) as shown in FIG. 8 between minimizing the heating power supplied to the injector and the associated rise time. ) Exists. As can be readily appreciated, the power used to heat the injector is limited by the battery power used, and the injector rise time is limited by user performance requirements.

  In addition to the design and performance requirements described above, there is also a need to provide some control over the fuel / air ratio required by the exhaust aftertreatment procedure and / or the start control technique. At a minimum, the fuel injector must have the ability to meet the required maximum / minimum flow ratio, from cranking to idle to other engine operating conditions. However, in some configurations, emissions may be maximally reduced by injecting steam only during periods when the engine cycle intake valve is open. Such an injection profile is shown in FIG. 9 along with the approximate time associated with each part of the four stroke cycle. As shown, at 1500 rpm, valve opening injection is achieved by controlling the steam flow rate so that a 20 ms injection period is followed by a 60 ms period in which little or no steam is delivered to the engine. Will be.

  Conventional valve designs used to regulate steam fuel injector flow rates can result in an adverse increase in thermal mass, which is the mass that must be heated to achieve a temperature sufficient to evaporate the liquid. Are known. This increase in thermal mass is undesirable because it increases the rise time of the injector (see FIG. 8), thereby degrading the quality of the steam produced by the injector during startup and / or transient operation. .

  Referring to FIG. 10, an exemplary schematic diagram of a control system 2000 is shown. The control system 2000 is used to operate the internal combustion engine 2110, the liquid fuel supply valve 2220 in fluid communication with the liquid fuel supply source 2010 and the liquid fuel injection path 2260, the liquid fuel supply source 2010, and the capillary channel 2080. And an oxidant gas supply valve 2020 in fluid communication with an oxidant gas supply source 2070 and a capillary channel 2080. The control system includes a controller 2050, which typically includes an engine speed sensor 2060, an intake manifold air thermocouple and intake pressure sensor 2062, a refrigerant temperature sensor 2064, an exhaust air / fuel ratio sensor 2150, a fuel supply. A plurality of input signals are received from various engine sensors such as the pressure sensor 2012. In operation, the controller 2050 executes a control algorithm based on one or more input signals, followed by an output signal to the oxidant supply valve 2020 for cleaning the blocked capillary passage according to the present invention. Heating power to a power supply that generates 2024, generates an output signal 2014 to the liquid fuel supply valve 2220, generates an output signal 2034 to the fuel supply valve 2210, and delivers power to heat the capillary 2080 A command 2044 is generated.

  In operation, the system proposed here feeds back the heat generated during combustion by using exhaust gas recirculation heating, thereby allowing the liquid fuel to pass through the capillary flow path 2080. It can also be configured to heat sufficiently to substantially evaporate, reducing, eliminating or supplementing the need to heat capillary channel 2080 electrically or otherwise.

  As can be appreciated, the preferred form of fuel injector shown in FIGS. 1-7 may be used in connection with other embodiments of the present invention. Referring back to FIG. 1, the injector 10 may include means for cleaning deposits that form during operation of the injector 10. As envisioned, the means for cleaning the deposits includes fluidly communicating each capillary channel 12 with a solvent, and each capillary channel when the solvent is directed into each capillary channel 12. Twelve in-situ cleaning steps. A wide variety of solvents can be used, but the solvent here may consist of liquid fuel from a liquid fuel source. In operation, during the cleaning of the capillary channel 12, the heat source should be shut down for a long time, i.e. switched off. As will be appreciated by those skilled in the art, the injector design shown in FIGS. 6 and 7 is readily adapted to perform in-situ solvent cleaning.

  Referring again to FIG. 1, the heated capillary channel 12 of the fuel injector 10 produces an evaporated fuel stream that condenses in the air and is evaporated, commonly referred to as an aerosol. A mixture of fuel, fuel droplets, and air can be formed. Similarly, referring again to FIG. 7, the heated capillary channel 112 of the fuel injector 100 produces an evaporated fuel flow that can condense in air to form an aerosol. it can. Compared to conventional automotive port fuel injectors that deliver fuel sprays consisting of droplets in the range of 150 to 200 μm Sauter mean diameter (SMD), this aerosol has an SMD of less than 25 μm, preferably 15 μm Having an average droplet size of less than SMD. Thus, most of the fuel droplets produced by the heated capillary injector according to the present invention will be carried into the combustion chamber by the air flow, regardless of the flow path.

  The difference in droplet size distribution between the conventional injector and the injector disclosed herein is particularly important in cold start and warm air conditions. Specifically, when using a conventional port fuel injector, a relatively cold intake air is used to evaporate a sufficiently large amount of fuel droplets that collide with the intake components to produce an ignitable fuel / air mixture. Excess fuel must be supplied to the manifold parts. Conversely, the vaporized fuel and fine droplets produced by the fuel injectors disclosed herein are essentially unaffected by the temperature of the engine components at start-up and are therefore excessive in engine start-up conditions. Eliminates the need for fuel supply. The elimination of excess fuel supply combined with more precise control of the fuel / air ratio for the engine given by the use of the fuel injector disclosed herein can be produced by an engine using a conventional fuel injector system. Compared with the above, the emission at the cold start is remarkably reduced. In addition to reducing excess fuel supply, the heated capillary injector disclosed herein further allows fuel lean operation during cold start and warm air, resulting in activation of the catalytic converter and exhaust pipe. It should also be noted that the emissions are significantly reduced.

Fuel is less than 7kg / cm ² (100psg), preferably less than 4.9kg / cm ² (70psg), more preferably, less than 4.2kg / cm ² (60psg), more preferably, 3.2 kg / cm ² (45 psg) can be delivered to the injector disclosed herein. This embodiment forms an aerosol droplet distribution that is mostly in the 2-30 μm SMD size range and the average droplet size is about 5-15 μm SMD when the evaporated fuel is condensed in the air at ambient temperature. It is known to produce evaporative fuel. The preferred size of the fuel droplets to achieve rapid and near complete evaporation at the cold start temperature is less than about 25 μm. This result shows that approximately 10.2 to 40.8 kg / sec (100 to 400 W), for example, 20.4 kg / sec (200 W), corresponding to 2 to 3% of the energy amount of the evaporated fuel, is applied to the capillary bundle. To achieve this. As an alternative to heating the tube along its length, the length of the flow path can be by one or a combination of induction heating by an electrical coil placed around the flow path, or heat transfer by conduction, convection, or radiation. Heating with other heat sources arranged relative to the flow path so as to heat. After a cold start and warm-up, the capillary bundle need not be heated, and an unheated capillary tube can be used to supply a sufficient amount of liquid fuel to an engine operating at normal temperature. Approximately 20 seconds (or preferably less than 20 seconds) after starting the engine, the power used to heat the capillaries is shut off and liquid injection is started for normal engine operation. become. As one skilled in the art can readily appreciate, normal engine operation will be performed by liquid fuel injection in the form of continuous injection or pulse injection.

  The fuel injectors disclosed herein can be located at the same location as existing port fuel injectors in the engine intake manifold or elsewhere along the intake manifold. The fuel injectors disclosed herein provide advantages over systems that produce large droplets of fuel that must be injected behind a closed intake valve while starting the engine. Preferably, the outlet of the capillary tube is arranged on the same plane as the intake manifold wall, similar to the arrangement of the outlet of a conventional fuel injector.

  A laboratory bench test was performed by supplying gasoline at a constant pressure to the capillaries described below with a microdiaphragm pump system. Droplet peak size and drop size distribution were measured using a Spray-Tech laser diffraction system manufactured by Malvern. Droplet dimensions are expressed in Sauter mean diameter (SMD). SMD is the diameter of a droplet whose surface / volume ratio is equal to the surface / volume ratio of a complete spray and is related to the mass transfer characteristics of the spray.

  FIG. 11 shows the liquid mass flow rate and the vapor mass flow rate of fuel through a single 1.5 inch capillary as a function of the capillary pressure drop. In FIG. 11, the flow through a “normal wall” capillary having an OD of 0.081 cm (0.032 inch) and an ID of 0.051 cm (0.020 inch) is applied to an OD of 0.081 cm (0.032 inch). And flow through a “thin wall” capillary having an ID of 0.028-0.029 inches. In the case of the results shown in FIG. 11, each capillary was constructed from 304 stainless steel, but it should be readily understood that similar results can be achieved using each capillary with Inconel 600. . An important usage difference between stainless steel 304 and Inconel 600 in this application is in the electrical resistivity of each material. Specifically, because Inconel 600 has a higher resistivity than stainless steel 304, a higher resistivity is important to obtain compatibility with the electrical circuit used to supply heat to the capillary. It is more suitable for this application.

As shown in FIG. 11, the “thin wall” capillary has a large flow area, so both the liquid and vapor mass flow rates are significantly increased compared to the “normal wall” capillary. The vertical line drawn with a solid line in the graph represents a design point based on a total fuel injector pressure of 3.5 kg / cm ² (50 psi) and a capillary pressure drop requirement of less than 10%. At this design point, the results of FIG. 11 show that the liquid and vapor flow requirements for most automotive port fuel injection applications are met by 2 to 4 thin-walled 3.8 cm (1.5 inch) capillaries. Is shown.

  FIG. 12 shows the fuel droplet size (SMD, μm) in a 3.8 cm (1.5 inch) thin wall capillary as a function of the resistance setting. This result shows that the droplet size varies significantly with the capillary temperature setting expressed as the ratio of the heated capillary resistance (R) to the capillary resistance (Ro) when cold. However, the preferred range of temperature set points for stainless steel capillaries is about 1.12 to 1.2 in R / Ro designation. For stainless steel, this range corresponds to a bulk capillary temperature of about 140-220 ° C.

FIG. 3 is a partial cross-sectional view of a multi-capillary fuel injector having an electronically heated capillary bundle disposed upstream of a solenoid operated fuel throttle valve, according to a preferred configuration. It is an enlarged view of the capillary bundle of the embodiment of FIG. 3 is a plan view of a preferred form of a diaphragm plate 40. FIG. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A. It is a top view of the preferable form of an orifice plate. FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A. FIG. 4 is a diagram showing a cooperative action state of the throttle plate of FIG. 3B and the orifice plate of FIG. 4B when arranged in an open position so as to form a fuel flow path. FIG. 4 is a diagram showing a state of cooperative action of the throttle plate of FIG. 3B and the orifice plate of FIG. 4B when arranged in a closed position so as to block a fuel flow path. FIG. 6 is an isometric view of another multi-capillary fuel injector having an electronically heated capillary bundle disposed upstream of a solenoid operated fuel throttle according to another preferred form of injector. FIG. 7 is a partial cross-sectional side view of the multiple capillary fuel injector of FIG. 6. FIG. 6 is a chart showing the trade-off (compatibility) between minimizing the power supplied to the injector and minimizing the rise time associated with the injector for different heating masses. It is a chart which shows that an emission is reduced to the maximum by injecting steam only in the period when the intake valve of an engine cycle is open. 1 is a schematic diagram of a fuel delivery and control system according to a preferred embodiment. FIG. 4 shows the liquid mass flow rate and the vapor mass flow rate of fuel through a single 3.8 cm (1.5 inch) capillary as a function of capillary pressure drop. FIG. 4 shows fuel droplet size (SMD, μm) in a 3.8 cm (1.5 inch) thin wall capillary as a function of resistance set point.

Claims (20)

In a fuel injector with a central hole for evaporating liquid fuel and metering it to an internal combustion engine,
(A) a capillary bundle disposed in the central hole of the fuel injector ; (i) a plurality of capillary channels, each having a plurality of thin-walled capillary flows each having an inlet end and an outlet end; And (ii) a spindle piece that structurally supports the capillary channel, the spindle end being arranged to engage each of the outlet ends of the plurality of capillary channels of the capillary bundle. And (iii) a fixed disk for attaching the capillary bundle adjacent to each outlet end of the plurality of capillary channels, each of the plurality of capillary channels having a thickness of the fixed disk. A capillary bundle comprising a stationary disk extending therethrough and attached to the central hole of the fuel injector ;
(B) a heat source disposed along each of the plurality of capillary channels, wherein at least part of the liquid fuel in each of the plurality of capillary channels is changed from a liquid state to a vapor state, A heat source operable to heat a vaporized fuel stream to a level sufficient to be delivered from each of the outlet ends of the plurality of capillary channels;
(C) a valve for metering and delivering substantially evaporated fuel to the internal combustion engine, the valve disposed on the downstream side of each of the outlet ends of the plurality of capillary channels;
The fuel injector according to claim 1, wherein the spindle piece functions as a part of an electric path used to supply electric power to the heat source .   The valve for metering fuel to the internal combustion engine includes a low mass plate valve assembly having a low wet area actuated by a solenoid, the low mass plate valve assembly comprising a throttle plate, an orifice plate, The fuel injector according to claim 1, further comprising:   The fuel injector of claim 2, wherein the throttle plate comprises a plurality of throttle openings that allow fuel to pass from each of the outlet ends of the plurality of capillary channels.   The orifice plate includes an inner seal ring and an outer landing to prevent fuel flow from each of the outlet ends of the plurality of capillary channels when the orifice plate is in sealing engagement with the restrictor plate. The fuel injector according to claim 2, further comprising a ring.   The fuel injector of claim 1, wherein the valve for metering fuel into the internal combustion engine is a low mass ball valve assembly actuated by a solenoid.   The low-mass ball valve assembly includes a ball connected to the solenoid, a conical seal surface, and a spring force operable to press the ball against the cone and prevent fluid flow from the injector. 6. The fuel injector according to claim 5, further comprising a spring having a dimension that provides the same.   An outlet orifice is further provided, wherein movement of the solenoid caused by applying electricity to the solenoid pulls the ball away from the conical sealing surface and allows fuel to flow through the outlet orifice. The fuel injector according to claim 6. Each of the plurality of capillary channels is formed in a tube selected from the group consisting of stainless steel and Inconel and has an inner diameter of about 0.051 cm to 0.076 cm and a length of about 2.54 cm to 7.62 cm. It has, The fuel injector of any one of Claims 1-7 characterized by the above-mentioned. (D) further comprising means for cleaning the precipitate formed during operation of the injector;
9. The method of claim 1 wherein the means for cleaning the precipitate uses a solvent containing liquid fuel from a liquid fuel source and the heat source is turned off during cleaning of the capillary passage. The fuel injector according to any one of claims.   The fuel injector according to claim 1, wherein the heat source includes a resistance heater. In a method for delivering evaporated fuel to an internal combustion engine,
(A) a step for supplying the liquid fuel to the capillary bundle disposed within the central bore of the fuel injector, the capillary tube bundle, and the capillary channel of the plurality of thin-walled (i) a fuel injector, (ii A spindle piece that structurally supports the capillary channel, the spindle piece having a spindle end disposed to engage each of the outlet ends of the plurality of capillary channels of the capillary bundle; (Iii) a fixed disk for attaching the capillary bundle adjacent to each outlet end of the plurality of capillary channels, each of the plurality of capillary channels extending through the thickness of the fixed disk; A stage comprising a fixed disk attached to the central hole of the fuel injector;
(B) heating the liquid fuel in the plurality of capillary channels of the fuel injector and passing the evaporated fuel through outlets of the plurality of capillary channels;
And (c) metering the evaporated fuel into a combustion chamber of the internal combustion engine through a valve disposed downstream of each outlet of the plurality of capillary channels. .   12. The method of claim 11, wherein the step of metering evaporated fuel into the combustion chamber of the internal combustion engine is limited to starting and warming up the internal combustion engine.   The method of claim 12, further comprising delivering liquid fuel to the combustion chamber of the internal combustion engine when the internal combustion engine is in a sufficiently warmed state. Periodically cleaning the plurality of capillary channels, wherein the step of periodically cleaning comprises (i) stopping the heating of the plurality of capillary channels, and (ii) removing the solvent from the Supplying a plurality of capillary channels, and substantially removing precipitates formed in the plurality of capillary channels;
14. A method according to any one of claims 11 to 13, wherein the solvent comprises liquid fuel from a liquid fuel source.   In step (c), the valve for metering fuel into the internal combustion engine is a low mass plate valve assembly having a low wet area actuated by a solenoid, the low mass plate valve assembly comprising: The method according to claim 11, comprising a diaphragm plate and an orifice plate.   16. The method of claim 15, wherein the throttle plate comprises a plurality of throttle openings that allow fuel to pass from each outlet of the plurality of capillary channels.   The orifice plate includes an inner seal ring and an outer landing ring to prevent fuel flow from each outlet of the plurality of capillary channels when the orifice plate is in sealing engagement with the throttle plate. The method according to claim 16, comprising:   15. In step (c), the valve for metering fuel to the internal combustion engine is a low mass ball valve assembly operated by a solenoid. The method described in the paragraph.   The low mass ball valve assembly includes a ball connected to the solenoid, a conical seal surface, and a spring force operable to press the ball against the conical portion and prevent fluid flow from the injector. 19. A method according to claim 18, comprising a spring having a dimension to provide.   20. The method of claim 19, wherein the movement of the solenoid caused by applying electricity to the solenoid pulls the ball away from the conical sealing surface and allows fuel to flow through the exit orifice. .

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