NL8620298A - DIRECT FUEL INJECTION BY COMPRESSED GAS. - Google Patents

Description

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8620288

Direct ^ lDaraxitastofi.nspu ± t ± ng_d.oor_m ± c3caeX of compressed gas.

The invention relates to the injection of dosed quantities of fuel into the combustion chamber of an internal combustion engine.

In order to obtain the more desirable levels of fuel efficiency and the control of emissions, it is desirable to control the position of the fuel cloud in the combustion chamber. It has been observed that the preferred location of the cloud is not constant, and in particular varies with the rotor load, which itself is related to the engine speed. In two-stroke engines, fuel cloud control is of particular importance in limiting fuel loss through the exhaust port, which cannot be completely closed during at least part of the fuel injection period.

It is clear that at low loads, and therefore at low fuel feed rates, the amount of fuel penetration into the cylinder must be limited in order to limit the degree of dilution of the fuel by mixing with the air in the combustion chamber. The dilution of the fuel provides a lean mixture that is more difficult to ignite and difficult to maintain combustion until the entire fuel fill is burned. However, at high loads and high fuel feed rates, the penetration rate must increase to ensure that the larger amount of fuel has access to sufficient air (oxidizing agent) to effect combustion of all fuel.

The main object of the present invention is to provide a method of controlling the fuel supply to an engine so that the location of a fuel cloud can be varied to aid in more efficient combustion of the fuel.

For this purpose, there is provided a method of controlling fuel distribution in an engine with internal. 1120 2 9 i k.

r ------- -i - 2 -. combustion, comprising injecting fuel directly into the combustion chamber through a nozzle in such conditions that the fuel penetrates the combustion chamber over a first distance, varying said conditions depending on the requested engine load, which exceeds a certain value, in order to increase the distance of fuel penetration into the combustion chamber.

Suitably, the pressure affecting the delivery of the fuel through the nozzle can be stepped up at one or more selected levels of the requested engine load or the pressure can be gradually increased over one or more areas of the engine speed or load to vary the amount of fuel ingress.

More in detail, a method for controlling the fuel distribution in the combustion chamber of an internal combustion engine is provided, comprising combining a metered amount of fuel delivered, at the delivery pressure, and a gas mass, delivering the fuel gas mixture thus formed at a delivery pressure of the mixture 20i through a nozzle in the combustion chamber, controlling the pressure difference between the fuel and gas mass in order to obtain a substantially uniform pressure difference over the requested engine load. and regulating the pressure of the fuel gas mixture during delivery to the combustion chamber, so that said pressure increases above a certain value in dependence on the requested engine load, whereby the degree of penetration of the fuel into the chamber is enlarged.

Maintaining the steady pressure differential between the fuel and the gas mass simplifies the control of the metered amount of fuel thereby avoiding the need to compensate for the variation in that differential pressure.

Preferably, fuel ingress control is accomplished by varying the fuel pressure with the engine speed and consequently varying the gas pressure to maintain a steady differential pressure. Accordingly, the variation of the fuel pressure will end ! result in varying the pressure available for the delivery of the fuel> * gas mixture through the nozzle 862029 "-3-.

to the combustion chamber.

The pressure increases preferably take place at one or more selected engine speeds in the normal operating speed range / and it has been found that a mid-speed increase is sufficient in many engine applications.

When controlling a pressure difference between the gas and the fuel supplied therein, certain advantages are obtained from the controls, which rely on varying the pressure of the fuel as the control function, and thereby causing a variation in the gas pressure to maintain the selected differential pressure.

One of the advantages is that the gas is less viscous than liquid fuel and thus, in a control state, the controlled gas pressure will not be affected by flow rate variations through the pressure regulator. As a result, the differential pressure is less sensitive to a variation of the flow rate of either the fuel or the gas. This feature is of particular importance when the pumps, which provide the fuel and the gas, are motor driven and have flow rates that are strongly related to the speed.

Accordingly, another object of the present invention is to provide a fuel gas control system particularly suitable for inclusion in a fuel injection system, wherein fuel and gas are supplied under pressure.

To this end, a fuel injection system for internal combustion engines is provided, wherein a metered amount of pressurized fuel is supplied into a gas to form a fuel gas fill, characterized in that the fuel pressure is regulated to a re-selected value and the gas pressure relative to the fuel pressure is controlled to maintain a certain pressure difference between the fuel and the gas during the metering of the fuel.

Suitably, the controlled pressure of the fuel can be selected between at least two determined values.

Preferably, the variation of the regulated fuel pressure is accomplished at a selected speed, within the normal | operating speed range of the motor, and the variation is at! preferably an increase when the engine speed exceeds the selected value 8 * 20 290 - 4 -.

A corresponding decrease :: occurs when the engine speed drops below the selected value.

Preferably, the fuel pressure is controlled at a certain value relative to the atmospheric pressure.

In accordance with another feature of the present invention, for an engine fuel system, there is provided a fuel pressure regulator set to provide a given fuel output pressure, and means controlling said pressure depending on a selected engine condition of a given size may vary.

Suitably, the predetermined fuel yield pressure is adjusted by a resilient member which is pre-tensioned to a set value, the means for varying the yield pressure adjusting the amount of tension on the resilient member. resilient member a spring that is tensioned or compressed to such an extent as to provide a load necessary to set the required fuel base pressure. The amount of compression or extension of the spring is increased in order to increase the pressure of the fuel yield u when the engine reaches a certain load and is then reduced when the engine speed drops below the selected load.

In this patent application, the penetration of the fuel jet is varied by adjusting the fuel delivery pressure in the combustion chamber, relative to a particular change or changes in the requested engine load, this demand being possible in a number of ways in many engine applications. is the engine speed; an indication of the engine load in most operating conditions, especially when the engine is normally operating in specific speed ranges, such as marine outboard engines. Accordingly, when the engine speed is sensed in an appropriate manner, and relatively simple scans are required, the engine speed is continuously monitored1 in order for the occurrence of the load change, whereby the change in fuel penetration must be made, to be reduced. touch.

··; j r - 5 - '. The invention will be further elucidated with reference to the annexed drawing.

Figure 1 shows an axial section of a two-stroke engine, provided with a system for directly injecting fuel into the cylinder.

Figure 2 shows a partial cross-sectional view of a fuel metering and injection unit suitable for use with the engine shown in Figure 1.

Figure 1 shows a cross section of a combined fuel and air pressure regulator, suitable for use with the dosing and injection unit according to Figure 2, schematically shown together with other components of a fuel injection system.

In Figure 1, the engine 109 is a single-cylinder two-stroke engine, of the conventional construction, with a cylinder 110, a crankcase 111 and a piston 112 reciprocating in the cylinder 110. The piston 112 is through the connecting rod 113 coupled to the crankshaft 114. The crankcase is provided with air induction ports 115, which includes the conventional tongue valves 119 and three transfer ports 20 116 (only one is shown), connecting the crankcase to the respective transfer ports, two of which have 117 and 118 are indicated, while the third is equal to 117 and is on the opposite side of gate 118.

The transfer ports are each arranged in the wall of the cylinder 110, their respective top edge being located in the same diametrical plane of the cylinder. An outlet port 120 is disposed in the wall of the cylinder, generally opposite the central transfer port 118.

The releasable cylinder head 121 has a combustion cavity 122 into which the spark plug 123 inserts. The cavity 122 is placed substantially symmetrically with respect to the axis of the cylinder, and the spark plug is located on this axis. The fuel injector 124 is placed in the wall of the cylinder 110 between the transfer ports and the cylinder head. In the shown configuration, the injection nozzle 124 is located directly above the central transfer port 118.

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The injector 124 is an integral part of a fuel metering and injector system, with air entrained fuel directly into the combustion chamber of the '862029 8 .................... - 6 - engine is injected by the pressure of the air supply. A particular embodiment of the fuel metering and injection unit is shown in Figure 2, which represents a type of metering injection unit in which the fuel and air pressure control system of the present invention can be used.

The fuel metering and injection unit in Figure 2 includes a suitable metering device 130, such as an automatic injection device with throttle body coupled to an injection body 131 with a waiting chamber 132 therein. Fuel is supplied from a fuel pump (not shown) through the fuel inlet port 133 to the metering device 130, which dispenses an amount of fuel into the waiting chamber 132 in accordance with the amount of engine fuel requested. Excess fuel supplied to the metering device is returned to a fuel container via the fuel return port 134. The particular construction of the fuel metering device 130 is not critical to the present invention and any suitable device can be used.

During operation, the waiting chamber 132 is pressurized 20 by air supplied through an air inlet port 145 into the body 131. An injection valve 143 is operated to allow the air to defeat the metered amount of fuel from the chamber 132 through the injection nozzle. 142 from the engine in a combustion chamber !. The injection valve injection valve 143 has the construction of a poppet valve, which opens inwardly into the combustion chamber, ie, outwardly of the waiting chamber.

The injection valve 143 is coupled, via a valve stem 144, which extends through the waiting chamber 132, to the armature 141 of a soloid 147, which is placed in the injection body 131.

! The valve 143 is biased in the closed position under the bias of the ring spring 140 and is opened by energizing the solenoid 147. The energizing of the solenoid is controlled in a time relationship with the engine cycle to release the fuel from the waiting chamber 132 to the engine combustion chamber.

Other details of the operation of the fuel metering and injection systems, which have a waiting room, as described with reference to Figure 2, are known from 8620298-7.

Australian Patent Application No. 32132/84 and the corresponding U.S. Patent Application 7,40067, filed April 2, 1985, each of which are hereby incorporated by reference. take.

It will be clear that the fuel is supplied to the waiting chamber 132 by the dosing device 130 against the pressure of the air contained in the chamber. Accordingly, the pressure difference between the fuel supply at the metering device and the air in the waiting room applies to the amount of fuel that will be delivered to the waiting room. In view of the required accuracy of the fuel metering, both in terms of fuel savings and control of emissions, it is important to control this differential pressure efficiently.

Figure 3 shows a fuel injection system with a combined fuel and air regulator, which is suitable for use with the fuel metering and injection unit, as described with respect to Figure 2. However, it will be understood that the regulator will be described below with reference to Figure 20. 3, can be used in other fuel metering and injection systems and is not limited to use in the system described with reference to Figure 2.

In Figure 3, the fuel injection system comprises a fuel metering and injection unit 5, to which air and fuel 25 are supplied from the compressor 2 and the fuel holder 6 via the controller 10, respectively. The fuel is supplied from the holder 6 by the low-pressure booster pump 3 to the high-pressure pump 7 via the passage 18 in the controller; 10.

The regulator 10 includes a fuel pressure control part 9 and an air pressure control part 11 which are incorporated in a unitary construction. The fuel control chamber 12 has a wall I formed by the flexible membrane 13 mounted around its peripheral edge. On the diaphragm 13, a valve member: 14 14 is mounted which cooperates with the port 15 which is arranged in the wall 17 of the fuel control chamber opposite the diaphragm 1 13. The port 15 communicates with the low pressure fuel passage 18 which are on turn is connected to the | i delivery side of the low pressure pump 3 and the suction side of the high j 1¾ & 9 A fk

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- 8 - pump pressure 7.

The high-pressure fuel inlet passage 20 connects the fuel control chamber 12 to the delivery side of the high-pressure fuel pump 7. The one-way valve 21 between the passage 5 18 and the chamber 12 is only slightly pre-loaded so that the low pressure fuel of the passage 18 can flow through the fuel chamber 12 to purify the high pressure fuel chain and air injector 5.

The membrane 13 is placed by the spring 25 such that normally the valve 14 comes into a position in which the port 15 is closed. The spring support plate 24 normally contacts the retaining member 19 mounted on the end wall 26 of the body of the control member. The spring support plate 24 is mounted on the membrane 27, which divides the control cavity 18.

The part 29 of the control cavity on the spring side of the membrane 27 is exposed to atmospheric air via the port 22, while the part 30 on the opposite side of the membrane 27 can optionally be connected to the controlled air source via the port 31 and the solonoid valve 49. When air pressure is applied through the port 31 to the portion 30 of the control cavity 28, the membrane 27 and the support plate 24 of the move the spring to the right, as shown in the drawing, in order to effect further compression of the spring 25. The amount of movement of the support plate 24 to the right is limited by the edge band 32 of the support plate 24 in contact with the annular shoulder 33 on the body of the controller.

Due to the pressure of the fuel in the control chamber 12, which exceeds the regulated pressure, the membrane 13 is displaced against the action of the spring 25, and the valve 14 is disengaged from the port 15, so that fuel passes through the port 15 can flow to passage 18 and thus reduce the pressure in control chamber 12 to the required value.

Thus, it is clear that the application of the control air to the portion 30 of the control air cavity 28 will increase the spring pressure on the membrane 13 by a certain amount, which in turn will increase the relief pressure of the valve 14. and thus the fuel pressure at the injection unit 5! supplied by the high pressure pump 7, in accordance with this. 862029 8 .......... '' ............ 1 - 9 - are increased.

In order to reduce the required pressure of the air admitted to the portion 30 of the control cavity, a spring (not shown) may be provided between the support plate 24 and the end wall 26 to partially counteract the spring 25.

The operation of the solonoid valve 49, in order to increase the fuel delivery pressure, can be influenced by a suitable engine speed sensor provided for operating a switch when the engine speed reaches a selected value. When actuated1, the switch energizes the solonoid valve 49 so that air from the controlled air supply to the injection unit 5 is admitted to the portion 30 of the control cavity 28. Applying pressure by this air to the membrane 27 will move the support plate 24 so that the edge band 15 32 will touch the shoulder 33, thereby increasing the load exerted by the spring 25 on the membrane by a set amount.

The operation of the solonoid valve 49 and the control cavity 28 to increase the fuel pressure can be adjusted to provide more than one increase in the controlled fuel pressure. Optionally, an electrically operated device can be used to perform the adjustment. The current supplied to the device can be changed to effect adjustment of the membrane movement. A suitable hysteresis function is preferably provided in the operation of the solonoid valve 49 in order to prevent a "search" between the varying fuel pressure.

The fuel pressure control part 9 of the composite fuel and air pressure control part 11, as described 30! With reference to Figure 3, it can be constructed as a separate fuel pressure regulator with the controlled pressure variable during operation. The desirability of an adjustable injection pressure has previously been discussed as a means of varying fuel ingress into the combustion chamber, and is equally applicable to an injection system where liquid fuel is injected only as for systems where liquid fuel is in air or any other suitable gas is carried along. Accordingly, the fuel pressure control member 9 can be used as a variable pressure regulator '862 029 8' -10- in injection systems that only inject liquid.

In Figure 3, the fuel chamber 12 communicates, via the passage 35, with the chamber 36 in the air control section 11 and is separated from the air pressure chamber 37 by the membrane 38. The air pressure chamber 37 communicates via the passage 39; with the air from the compressor 2, and the air outlet passage 40 extends from the chamber 37 to the injection unit 5. The diaphragm 38 carries the valve 41, which interacts with the port 42 which communicates with the air about line 43.

Spring 45 applies pressure to diaphragm 38 in order to normally keep valve 41 open. Accordingly, the valve 41 will open the port 42 when the air pressure in the chamber 37 and the action of the spring 45 together is sufficient to overcome the force exerted on the membrane 38 by the fuel pressure in the chamber 36. Accordingly, it will be appreciated that the air pressure will always be less than the fuel pressure and that is a magnitude represented by the force exerted by the spring 45 on the membrane 38.

The controller described above will, in use, control the pressure of the fuel supplied to the injection unit 5 by the pump 7 with respect to atmospheric pressure, and control the pressure of the air supplied to the fuel injection unit with respect to the fuel pressure, so that during the operation of the fuel injection unit there is a certain pressure difference between the fuel and air supplies. In addition, by applying air pressure to the portion 30 of the control unit 28, the regulated fuel pressure can be reduced by a set amount, and the air pressure will consequently drop accordingly. correspondingly enlarged by the same size so that the same differential pressure is maintained between the fuel and the air supplies to the fuel metering and injection unit. The penetration of the fuel jet can thus be changed without other settings or corrections for metering the fuel 1! ! 35 [dust.

! The rate of change of the air pressure, performed for the delivery of the fuel air mixture to the combustion chamber, is chosen for each engine, experimentally depending on the geometry of the engine, and the degree of interior & & ft "ft fi required

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- 11 - Penetration of fuel at varying loads or speeds.

In a particular example, which is applicable to a two-stroke engine with a displacement of 0.4 liters per combustion chamber, the air pressure is increased from 250 to 500 KPA at an engine speed of 2500 revolutions / minute located mid-point. engine speed range.

The above-described fuel pressure regulator and the fully united fuel and air pressure differential regulator. . can be used in conjunction with the fuel metering and delivery system described with respect to Figure 2, and as described in the associated Austra; Patent Application No. 32132/84 and, may be used in the fuel supply of a two-stroke engine, as described in co-pending Australian Patent Applications Nos. PH 01559, PH 1515 and PH 3344 entitled "Improvements in direct fuel injection engines" and in patent applications filed in Australia and other countries, which have the same priority as Australian patent applications. The content of the descriptions of said patent applications is here as 20; reference included.

|| In the above description regarding! the drawing refers to the use of the present invention in conjunction with a two-stroke spark ignition engine with reciprocating piston, however, it will be appreciated that the invention may also be applied to spark ignition four-stroke engines and / or other configuration , such as a rotary piston. The invention can be applied to internal combustion engines for all applications and particularly useful in striving for a contribution to fuel economy and control of emissions in engines for or in vehicles, including cars, motorcycles and boats including outboard engines .

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Claims (21)

A method of controlling fuel distribution in a combustion chamber of an internal combustion engine, comprising injecting fuel directly into the combustion chamber through a nozzle and under conditions such that the fuel penetrates a first distance into the combustion chamber, and varying said conditions depending on the requested engine load, which is above a certain value, in order to increase the distance of penetration of the fuel into the combustion chamber. 2. A method according to claim 1, characterized in that a dosed amount of fuel is entrained in a gas to form a fuel gas filling, that the amount of fuel entrained is regulated in dependence on the requested engine load, that said fuel gas filling 15 the combustion chamber is injected directly through a nozzle under conditions such that the fuel penetrates the combustion chamber over a first distance, and that the said conditions are varied in dependence on the requested engine load, which is above a certain value, in order to increase the distance from the fuel entering the combustion chamber. 3. Method according to claim 1 or 2, characterized in that the conditions of injection through the nozzle,! that are changed are the differential pressure that the delivery of the i! ! 25 'creates fuel through the nozzle. Method according to Claims 1 to 3, characterized in that the said conditions are varied in: dependence on the engine operating at a speed above a certain value. A method according to claim 2 or the combination of claims 2 and 3, characterized in that the fuel is metered into the gas during delivery for entraining, and that the fuel is maintained at a certain pressure difference above the gas over almost the entire area of the requested motor load. A method according to claim 5, characterized in that the gas pressure causes the delivery of the fuel through the nozzle. 7. Method according to claims 5 or 6, characterized in that the fuel pressure increases in dependence on the requested engine load, which is situated above the specified values. value, thereby increasing the gas pressure accordingly. 8. Method of controlling the fuel distribution 5 in the combustion chamber of an internal combustion engine characterized by the delivery of a metered amount of fuel supplied at the fuel delivery pressure and a gas mass, the direct injection of the fuel gas mixture thus formed at a mixture delivery pressure by a nozzle to the combustion chamber, controlling the pressure difference between the tire dust and gas mass to provide a substantially uniform pressure difference over the requested engine load, and controlling the pressure of the fuel gas mixture during delivery to the combustion chamber, such that the said pressure in dependence on the requested engine load increases above a certain value, thereby increasing the degree of penetration of the fuel into the chamber. Method according to claim 8, characterized in that the fuel pressure is controlled in order to increase above said determined value in dependence on said requested engine load. Method according to any one of the preceding claims, characterized in that said determined value of the requested motor load is determined by determining the determined speed that the motor obtains. 11. An internal combustion engine fuel injection system, wherein an amount of pressurized fuel is metered into a gas to form a fuel gas filling, characterized in that the fuel pressure is regulated to a preselected value and the gas pressure is regulated relative to the gas pressure. 30 fuel pressure in order to maintain a certain pressure difference between the fuel and the gas during the dosing of the fuel. Injection system according to claim 11, characterized in that the regulated fuel pressure can be selected between at least two determined values. Injection system according to claim 11, characterized in that the regulated fuel pressure is increased in dependence on the requested engine load, which increases above a certain value. Injection system according to claim 11, characterized by 1 r 9 n? a β; U · * -J lm at * - 14 -. that the regulated fuel pressure is increased in dependence on the engine speed, which increases above a certain value. 15. A method for controlling the fuel distribution in a combustion chamber of an internal combustion engine, comprising preparing a dosed amount of fuel outside the combustion chamber, injecting said dosed amount of fuel into the combustion chamber through a nozzle applying a gas under pressure to the fuel, regulating said gas pressure in dependence on the requested engine load so that, when engine loads are requested below a certain value, the gas pressure has a first level for providing a first distance of penetration of the fuel into the combustion chamber, and at requested loads above said predetermined value, the gas pressure is at a second level above said first level in order to increase the ingress of fuel into the combustion chamber. A method according to claim 15, characterized in that the fuel is metered into the gas during delivery to form a fuel gas filling. 17. Fuel injection system by an internal combustion engine, characterized in that fuel is metered into a gas and propelled by the pressure of the gas to the engine, a combined fuel and gas pressure regulator includes a first means i for controlling the fuel pressure at a first predetermined pressure above atmospheric pressure, and a second means for controlling the gas pressure at a predetermined value above the fuel pressure. 18. Injection system according to claim 17, characterized in that the first member comprises a fuel chamber and an air chamber separated by a movable wall, a fuel inlet port and a fuel return port in said fuel chamber, means for optionally opening the said fuel return port depending on the movement of said wall in one direction, biasing means for withstanding movement of the wall in said direction, an air port in said air chamber for admitting atmospheric air therein, said biasing means and atmospheric air in the air chamber together allow the wall to move to open the ^ 0 <r «fi fa ...... · '11 te / a 3 ./ ii Ss ·' $ £ KsP * «R - 15 - • return port when the fuel pressure in the fuel chamber is greater than the said first determined pressure. 19. An injection system according to claim 18, characterized in that the second member comprises a gas chamber and another fuel chamber separated by another movable wall therebetween, said other fuel chamber communicating with the fuel chamber of the first member, and a gas inlet port and a gas bypass conduit port in said gas chamber, means for selectively opening said air bypass port depending on the movement of said other wall in one direction, further biasing means that said wall in said one direction moving, which means ... biasing means and the pressure in said air chamber effect movement of said others; wall to open said bypass port when the pressure of said determined value is greater than the pressure in the other fuel chamber. Injection system according to any one of claims 17 to 19, characterized in that means are provided for optionally increasing the force exerted by the biasing means, in order to increase said first determined pressure of the fuel. An internal combustion engine containing a fuel injection system in which the method of any one of claims 1 to 10, 15 or 16 can be used. 22, Internal combustion engine containing a fuel injection system according to any one of claims 11 to 14 and! 17 to 20. An internal combustion engine according to claims 21 or 22, wherein the engine is a two-stroke engine. 24, Car provided with an internal combustion engine according to any one of claims 21 to 23. An internal combustion engine according to any one of claims 21 to 23, which is an outboard engine. 1 ί: 0-0-0-0-0-0-0-0; j β k 9 is o f% ff% 'w L L5 / ij