JP2669820B2 - Method and fuel injector for controlling fuel distribution in a combustion chamber of an internal combustion engine - Google Patents

Description

The present invention relates to injecting a metered amount of fuel into a combustion chamber of an internal combustion engine. To increase the level of fuel efficiency and exhaust purification, it is desirable to control the position of the fuel spray in the combustion chamber. The preferable position of the fuel spray is not constant but varies depending on the engine load, and the load itself is related to the engine speed. In a two-stroke engine, control of fuel spray is especially important because it limits fuel loss through exhaust ports that are not completely closed in at least a portion of the fuel injection engine. At light loads and therefore at low fuel rates, the degree of penetration of fuel into the cylinder must be limited in order to reduce the dilution of the fuel by mixing with the air in the combustion chamber. Fuel dilution results in a lean mixture that is difficult to ignite and difficult to maintain combustion until the fuel charge is ignited. However, at high loads and high fuel supercharging rates, the fuel penetration must be increased in order to bring more fuel into contact with sufficient air (oxidant) to complete its combustion. It is a primary object of the present invention to provide a method of controlling fuel supercharging of an engine to vary the position of the fuel spray to promote efficient combustion of fuel. To this end, fuel is first introduced into the combustion chamber.
Injecting fuel directly into the combustion chamber through a nozzle under the condition of distance approach, and in order to increase the distance of entry of fuel into the combustion chamber in response to engine load demand exceeding a predetermined value, Varying the conditions including controlling the fuel distribution within the combustion chamber of the internal combustion engine. Desirably, the delivery pressure of the fuel through the nozzle is stepped up at one or more engine load demand levels, or the delivery of fuel at one or more engine speeds or load ranges, to modify the fuel penetration. The pressure can be increased progressively. More specifically, the step of mixing the fuel and the gas whose feed pressures are adjusted and the fuel-gas mixture thus formed are directly fed into the fuel chamber through the nozzle at the mixture feed pressure. Injection, adjusting the fuel-gas differential pressure to maintain a substantially uniform differential pressure over the entire engine load demand, and the fuel-gas mixture being fed into the combustion chamber. Controlling the pressure so that the pressure is increased in response to an engine load requirement above a predetermined value, and thus the fuel penetration into the combustion chamber is increased. A method of controlling fuel distribution is provided. Maintaining a steady differential pressure between the fuel and gas simplifies fuel metering control because it is not necessary to compensate for differential pressure variations in the control procedure. Preferably, control of the degree of fuel penetration is accomplished by varying the fuel pressure with engine speed, and thus varying the gas pressure to maintain a steady differential pressure. Fluctuations in fuel pressure therefore result in fluctuations in the pressure of the fuel-gas mixture through the nozzle into the combustion chamber. Preferably, the pressure increase is carried out at a selected engine speed or speeds within the normal operating speed range and it has been found that in many engine applications the pressure increase in the medium speed range is sufficient. When adjusting the differential pressure between the gas and the fuel fed into it, the fuel pressure as a control function is varied, and as a result, the gas pressure is varied to maintain a predetermined differential pressure. Unique benefits are obtained. One of its advantages is that since the gas has a lower viscosity than liquid fuel, the controlled gas pressure during regulation is not affected by flow rate fluctuations in the regulator. As a result, this differential pressure becomes insensitive to fluctuations in the flow rate of fuel or gas.
This is particularly significant if the pumps that deliver fuel and gas are driven by the engine and its output is significantly related to engine speed. Accordingly, another object of the present invention is to provide a fuel-gas conditioning system that is particularly suitable for use in fuel injection systems that use reduced fuel and gas. For this purpose, fuel under metered pressure is introduced into the gas to form a fuel-gas supercharged mixture, the fuel pressure is adjusted to a predetermined value, the gas pressure is adjusted with respect to the fuel pressure, Provided is a fuel injection system for an internal combustion engine, which maintains a predetermined differential pressure between fuel and gas during fuel metering. Desirably, the regulated pressure of the fuel is selected between at least two predetermined pressures. Preferably, the fluctuations in the regulated fuel pressure are carried out at a predetermined speed within the normal operating speed range of the engine, and the fluctuations are increased as the engine speed exceeds a predetermined value. When the engine speed drops below a predetermined value, the fuel pressure is correspondingly reduced. Preferably, the fuel pressure is adjusted to a predetermined differential pressure with respect to atmospheric pressure. According to another aspect of the present invention, in an engine fuel system, a fuel pressure regulator that is set to generate a predetermined fuel output pressure, and the fuel pressure is changed by a predetermined amount according to a specific engine state. And means are provided. Desirably, the predetermined fuel output pressure is set by elastic means prestressed to a set degree, and the output pressure varying means adjusts the degree of stress on this elastic means.
Preferably, the elastic means is resilient or compressed to the extent that it produces the load necessary to set the desired base fuel pressure. The compression or tension of the spring is increased to increase the fuel output pressure when the engine reaches a given load,
It is then reduced when the engine speed drops below a predetermined load. In this specification, in response to a specific change in the engine load requirement, the case where the fuel spray pressure is adjusted by adjusting the fuel feed pressure into the combustion chamber is described. It can be detected by various methods. In many engine applications, engine speed under most operating conditions is indicative of engine load. Especially in the case of an outboard engine, the engine is operated within a certain speed range. Therefore, since the engine speed is easily detected and a relatively simple sensor is required, it is possible to detect the engine speed and to detect the occurrence of load fluctuation in which the change of the fuel penetration degree should be performed. In the following, the fuel incorporated in the fuel injection system /
The present invention will be described with reference to the accompanying drawings showing an embodiment of an air pressure adjusting system. In the attached drawings, FIG. 1 is an axial sectional view of a two-cycle engine having a direct injection type fuel injection system, and FIG. 2 is a partial sectional view of a fuel metering injection system suitable for use with the engine of FIG. FIG. 3 is a cross-sectional view of a hybrid fuel / pneumatic pressure regulation system for use with the fuel metering injection system shown in FIG. 2 and the other elements and connections of the fuel injector. Referring to FIG. 1, the internal combustion engine 109 is a single-cylinder two-step internal combustion engine having a general structure as a whole, and includes a cylinder 110, a crankcase 111, and a piston 112 that reciprocates in the cylinder 110. Piston 112 is a connecting rod
It is connected to the crankshaft 114 by 113. The crankcase 111 has an intake port 115 with a normal reed valve 119, and three distribution passages 116 (only one of which is shown) connect the crankcase to each distribution port and two Only dispensing ports 117 and 118 are shown, and a dispensing port equivalent to dispensing port 117 is on the opposite side of dispensing port 118. The distribution ports are respectively formed in the wall of the cylinder 110,
The upper edges of each are located in the same diameter surface of the cylinder. The exhaust port 120 is formed in the wall of the cylinder substantially opposite to the center distribution port 118. The removable cylinder head 121 has a fuel cavity 122 into which a spark plug 123 protrudes. The cavity 122 is arranged substantially symmetrically with respect to the axis of the cylinder, and the spark plug is arranged on this axis. The fuel injector 124 is located in the wall of the cylinder 110 between the distribution port and the cylinder head. In the structure shown, the injection nozzle 124 is directly above the central distributor 118. The fuel injector 124 forms part of a fuel metering injection system, whereby fuel entrained in the air is directly injected into the combustion chamber of the internal combustion engine by the air pressure. The fuel metering injection system of the type shown in FIG. 2 is a typical fuel metering injection system to which the fuel / air pressure adjusting system according to the present invention can be applied. The fuel metering injection unit of FIG. 2 includes a suitable metering device 130, such as an automatic throttle valve fuel injector, which is connected to a fuel injector body 131 having a holding chamber 132. Fuel from fuel pump (not shown) to fuel inlet
It is sent to the metering device 130 through 133, and this metering device meters a fixed amount of fuel into the holding chamber 132 according to the fuel demand of the internal combustion engine. Excess fuel sent to the metering device is returned to the fuel tank through the fuel return port 134. The particular construction of the fuel metering device 130 is not critical to the invention, and any suitable device may be used. During operation, the holding chamber 132 is pressurized by the air supplied into the body 131 through the air inlet 145. The injection valve 143 is actuated to expel a metered amount of fuel from the holding chamber 132 through the injection nozzle 142 into the fuel chamber of the internal combustion engine by compressed air. The injection valve 143 of the injection nozzle,
A poppet valve structure that opens toward the inside of the combustion chamber, that is, from the holding chamber to the outside. The injection valve 143 is connected to an armature 141 of a solenoid 147 arranged inside the main body 131 via a valve shaft 144 passing through the holding chamber 132. The valve 143 is repelled to the closed position by the disc spring 140 and opened by utilizing the solenoid 147. The magnetization of solenoid 147 is timed with the engine cycle to direct fuel from holding chamber 132 to the fuel chamber. Details of the operation of a fuel metering injection system including a holding chamber as shown in FIG. 2 are described in Australian Patent Application 1984 32132 and corresponding US Patent Application 740067, which are incorporated by reference. Add as. It will be appreciated that fuel is pumped into the holding chamber 132 by the metering device 130 in opposition to the pressure of the air present in the holding chamber. Therefore, the differential pressure between the fuel feed pressure of the metering device and the air pressure inside the holding chamber is related to the amount of fuel fed into the holding chamber. It is important to control this differential pressure reliably in order to improve the fuel metering accuracy from the viewpoint of fuel saving and exhaust gas purification. FIG. 3 relates to a fuel injector including a fuel / air pressure regulation system suitable for use with the fuel metering injection system described with reference to FIG. However, it is understood that the fuel / air pressure adjusting system described in FIG. 3 can be used for other fuel metering injection systems, and is not limited to the fuel metering injection system described in the second. I want to be done. In FIG. 3, the fuel injector includes a fuel metering injection system 5, to which air and fuel are respectively sent from a compressor 2 and a fuel tank 6 through a fuel / air pressure adjusting system 10. It Fuel is delivered from the fuel tank 6 to the high pressure pump 7 by the low pressure lift pump 3 through a passage 18 in the fuel / air pressure regulation system 10. The fuel / air pressure adjusting system 10 includes the fuel pressure adjusting unit 9 and the air pressure adjusting system 11 as an integral structure. One wall of the fuel adjustment chamber 12 is formed of a flexible diaphragm fixed along its outer periphery. Affixed to this diaphragm 13 is a valve element 14, which cooperates with a port in the wall 17 of the fuel control chamber opposite the diaphragm 13. The port 15 communicates with a low pressure fuel passage 18, which communicates with the discharge side of the low pressure pump 3 and the suction side of the high pressure pump 7. A high-pressure fuel introduction passage 20 communicates the fuel adjustment chamber 12 with the discharge side of the high-pressure fuel pump 7. Since the one-way valve 21 between the passage 18 and the adjusting chamber 12 is slightly preloaded, the low-pressure fuel flows from the passage 18 through the fuel adjusting chamber 12 at the time of starting, and the high-pressure fuel circuit and the fuel metering injection system 5 The diaphragm 13 is urged by a spring 25 so that the valve 14 normally closes the port 15. Spring back plate
24 normally abuts a stopper 19 provided on the end wall 26 of the fuel / air pressure regulation system. This spring backboard is
It is fixed to a diaphragm 27 that divides the control cavity 28. Control cavity on the spring side of diaphragm 27
While 29 is connected to the atmosphere by port 22, the opposite portion 30 of diaphragm 27 is selectively in communication with a regulated air source through port 31 and solenoid valve 49. Air pressure through port 31 is part of control cavity 28
When added to 30, the diaphragm 27 and spring back plate 24 are moved to the right in the figure to further compress the spring 25. The rightward movement of the back plate 24 is limited by the contact of the edge band 32 of the back plate 24 with the annular shoulder 33 of the fuel / air pressure regulation system. When the fuel pressure in the regulating chamber 12 exceeds the regulating pressure, the diaphragm 13 is moved against the action of the spring 25, the valve element 14 is disengaged from the port 15 and the fuel is pumped from the port 15 into the passage 18. The pressure in the adjusting chamber 12 is lowered to a required value by circulating the liquid. In this way, application of control air to the portion 30 of the control air cavity 28 will increase the spring pressure on the diaphragm 13 by a predetermined amount, which will increase the release pressure of the valve element 14 and thus the fuel control by the high pressure pump 7. The fuel pressure delivered to the quantity injection system 5 is correspondingly increased. A spring (not shown) is placed between the back plate 24 and the end wall 26 to partially oppose the spring 25 to reduce the required pressure of the air introduced into the portion 30 of the control cavity 28. You can do it. By arranging a suitable engine speed sensor to activate the switch when the engine speed reaches a predetermined value, the solenoid valve 49 can be activated to increase the fuel delivery pressure. When the switch is activated, a portion of the air from the regulated air source to the fuel metering injection system 5 is introduced into the portion 30 of the control cavity 28, utilizing the solenoid valve 49. This air applies pressure to the diaphragm 27 to move the back plate 24, the edge band 32 contacts the shoulder 33, and the load applied to the diaphragm 33 by the spring 25 increases by a certain amount. The operation of solenoid valve 49 and control cavity 28 to increase fuel pressure can be configured to cause one or more increases in regulated fuel pressure. Alternatively, an electric actuator can be used for adjustment. The current applied to this device can be varied to regulate diaphragm movement. A suitable hysteresis function can be included in the operation of the solenoid valve 49 to prevent "hetting" between alternating fuel pressures. Hybrid fuel / air pressure regulation system 10 described above with reference to FIG.
The fuel pressure adjusting unit 9 can be configured as an independent fuel pressure adjuster that can change the adjusting pressure during operation.
Although it has been described above that the possibility of adjusting the injection pressure is desirable as a means for varying the degree of entry of fuel into the fuel chamber, this also applies to fuel injectors that inject only liquid fuel. Therefore, the fuel pressure control unit 9 can be used as a variable pressure regulator of a fuel injection system that injects only liquid fuel. Continuing with the description of the hybrid fuel / pneumatic pressure regulation system shown in FIG. 3, the fuel chamber 12 communicates with the chamber 36 in the air regulating section 11 through the passage 35, and the fuel chamber 12 also extends from the pneumatic chamber 37. Separated by diaphragm 38. This pneumatic chamber 37
Communicates with the air coming from the compressor 2 through the passage 39, and the exhaust passage 40 reaches the fuel metering injection system 5 from the air chamber 37. The diaphragm 38 carries a valve 41, which is in port 42.
And the port communicates with the air bypass passage 43. A spring 45 applies pressure to the diaphragm 38 to keep the valve 41 normally open. Therefore the air chamber 38
When the sum of the air pressure in and the action of the spring 45 exceeds the stress produced by the fuel pressure in the chamber 36 on the diaphragm 38,
Valve 41 opens port 42. Therefore, it will be appreciated that the air pressure is always lower than the fuel pressure by the amount of stress exerted by the spring 45 on the diaphragm 38. The above-mentioned fuel / air pressure adjusting system adjusts the fuel pressure sent to the fuel metering injection system 5 by the pump 7 to the atmospheric pressure during its use, and the air pressure for the fuel metering injection system 5 to the fuel pressure. Because of the adjustment, a predetermined pressure difference is generated between the fuel pressure and the air pressure during the operation of the fuel metering injection system. Further, by applying air pressure to the portion 30 of the control cavity 28, the adjusted fuel pressure is increased by a predetermined amount, and therefore the air pressure is also increased at the same rate, so that the pressure between the fuel pressure and the air pressure for the fuel metering injection system is increased. The same differential pressure is maintained at. Therefore, the fuel spray penetration can be changed without adjusting or modifying the fuel metering. The degree of change in air pressure to deliver the fuel / air mixture to the fuel chamber is determined experimentally for each engine depending on the engine's geometry and the required fuel penetration to accommodate load or speed variations. To be selected. In a practical example for a two-stroke engine with a displacement of 0.4 per fuel chamber, the engine's mid-speed range of 2500
At PPM the air pressure is increased from 250KPA to 500KPA. The aforementioned fuel pressure regulator and hybrid fuel / air pressure regulation system are used in combination with the fuel metering injection system described in FIG. 2 and in Applicant's co-pending Australian patent application 1984 32132. Applicant's co-pending application Australian Patent Applications No. PH01559, PH1991 and PH3
It can be used for fueling a two-cycle engine as described in the specification No. 344 and the patent applications claiming priority of these patent applications. The disclosure of the specification of the above-mentioned Japanese Patent Application is included by reference. In the above description of the attached drawings, the case where the present invention is applied to the two-cycle spark ignition type reciprocating piston is described. Please understand that the above can also be applied. INDUSTRIAL APPLICATION This invention is applied to the internal combustion engine of every use, and is especially effective in fuel saving and exhaust gas purification in engines, such as a motor vehicle, a motorcycle, and a boat including an outboard engine.

   ────────────────────────────────────────────────── ─── Continuation of front page                   (56) References Japanese Patent Laid-Open No. 59-60069 (JP, A)                 JP-A-58-155269 (JP, A)                 Showa 60-97371 (JP, U)                 US Patent 1149321 (US, A)                 US Patent 1166937 (US, A)

Claims (1)

(57) [Claims] A fuel-gas mixture is formed by entraining the metered fuel amount with the pressurized gas, and the fuel amount corresponds to the engine load when fuel is sent and entrained with the pressurized gas. Metered, wherein a fuel-gas mixture is injected directly into the combustion chamber through the nozzle at an injection pressure determined by the pressure of the pressurized gas, whereby fuel enters the combustion chamber over a first distance dependent on said injection pressure. In addition, when the engine is operating at least one of the engine speed and the engine load at a predetermined value or less, the engine is injected at a certain injection pressure, and one of the engine speed and the engine load is set at the predetermined value. When the value is exceeded, in response, the injection pressure of the fuel gas mixture is increased, which causes either the engine speed or the engine load to reach the pre-determined value. A fuel that exceeds a predetermined value and enters the combustion chamber by a second distance greater than the first distance, and a fuel portion of the fuel-gas mixture over at least one of the engine speed and the engine load; Is maintained at a pressure higher than that of the pressurized gas portion, a method for controlling combustion distribution in a combustion chamber of a spark ignition type internal combustion engine. 2. The method of claim 1, wherein the pressure of the pressurized gas causes the delivery of fuel through a nozzle. 3. The method of claim 1 wherein said injection pressure changes in response to an engine operating at a speed exceeding a predetermined value. 4. A method as claimed in claim 1 or 2, wherein the fuel pressure is increased in response to an engine speed and engine load of at least 1 above said predetermined value. 5. The metered fuel amount and gas sent at the fuel feed pressure are combined, and the fuel / gas mixture formed at the fuel / gas mixture feed pressure is injected directly into the combustion chamber through the nozzle, and the fuel / gas mixture is substantially spread over the engine load. Adjust the pressure difference between the fuel and gas to maintain a uniform pressure difference, and control the pressure of the fuel / gas mixture while sending the fuel / gas mixture into the combustion chamber. A method for controlling fuel distribution in a combustion chamber of an internal combustion engine, wherein the pressure of the gas mixture is increased in response to an engine load greater than or equal to a predetermined value, thereby increasing the range of fuel entry into the combustion chamber. 6. 6. The method of claim 5, wherein fuel pressure is adjusted to increase in response to an engine load greater than or equal to the predetermined value. 7. A method according to claim 1 or 5, wherein the predetermined value of engine load is determined by determining the engine that achieves the predetermined speed. 8. A method according to claim 1 or 5 used to operate a fuel injector of an internal combustion engine. 9. 6. The method according to claim 1, wherein the method is used to operate a fuel injection device of an internal combustion engine of a motor vehicle. 10. The method according to claim 1 or 5, which is used in an internal combustion outboard marine engine. 11. A first device for adjusting the fuel pressure to a first predetermined pressure higher than the atmospheric pressure, wherein a fuel-gas pressure combination adjustment device in the fuel injection device in which fuel is metered into the gas and sent into the engine by the pressure of the gas; A second device for adjusting the gas pressure to a predetermined value equal to or lower than the fuel pressure. 12. The first device includes a fuel chamber and an air chamber separated by a movable wall, a fuel introduction port and a fuel return port in the fuel chamber, and the fuel return port in response to a movement of the movable wall in one direction. A device that selectively opens, a biasing device that resists movement of the movable wall in the one direction, and a vent that is provided in the air chamber and allows the atmosphere to pass through the air chamber. 12. The fuel injection device according to claim 11, wherein when the pressure of the fuel in the combustion chamber is equal to or higher than the first predetermined pressure, the movable wall is moved to open a fuel return port. 13. The second device includes a gas chamber and another fuel chamber separated by another movable wall provided therebetween, wherein the another fuel chamber communicates with the first fuel chamber, A second device further comprising: a gas introduction port and a gas bypass port of the gas chamber; and a device for selectively opening the gas bypass port in response to movement of the other movable wall in one direction; Another urging device for urging one movable wall in the one direction is provided, and the other urging device and the pressure in the gas chamber move the other movable wall to cause the gas chamber to move. 13. The fuel injection device according to claim 12, wherein the gas bypass port is opened when the pressure is equal to or higher than the predetermined value. 14． 14. The fuel injection device according to claim 11, further comprising a device for selectively increasing the urging force provided by the urging device to increase the first predetermined pressure of the fuel. 15. In a fuel injector for an internal combustion engine in which the fuel quantity is metered under gas pressure to form a fuel-gas mixture, the fuel pressure is adjusted to a preselected value, and the adjusted fuel pressure is adjusted to at least two predetermined values. A fuel injection device selectable between a predetermined value and a gas pressure adjusted relative to the fuel pressure to maintain a predetermined pressure difference between the fuel and the gas during fuel metering. 16. 16. The fuel injection system of claim 15, wherein the regulated fuel pressure is increased in response to increasing engine load demand above the predetermined value. 17． 16. The fuel injector according to claim 15, wherein the regulated fuel pressure is increased in response to increasing engine speed demand above the predetermined value. 18. 17. The fuel injection device according to claim 11, which is a constituent element of an internal combustion engine. 19.2 Used in a two-cycle internal combustion engine
20. The fuel injection device according to any one of 3, 15, or 16. Claims 11, 12, 13, 15 for use in an automobile internal combustion engine
Alternatively, the fuel injection device according to any one of 16 above. 21. Claims 11, 12, which is a component of an internal combustion outboard marine engine.
The fuel injection device according to any one of 13, 15 and 16.