JP2006029100A - Fuel control method of multicylinder engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel control method of a 6-cylinder diesel engine, capable of actively reducing vibration of an engine, when injection-supply of fuel from an injector becomes impossible to a a certain cylinder among 6 cylinders. <P>SOLUTION: This fuel control method comprises a rotation recognizing means 100 for recognizing a rotation quantity of a crankshaft 11 by a cylinder before a combustion cycle of the cylinder. When the injection-supply of the fuel from the injector becomes impossible to a certain cylinder among 6 cylinders, the cylinder number of an object cylinder by the rotation recognizing means is changed so as to recognize the rotation quantity of the crankshaft with every cylinder of the whole 6 cylinders continuing in a combustion cycle before the combustion cycle of the cylinder, and is controlled so as to stop fuel supply of the injector for supplying the fuel to a cylinder coincident in an interval of the combustion cycle with a fuel unsuppliable cylinder, for uniformizing the interval of the combustion cycle between the cylinders positioned on both front and rear sides of the combustion cycle by sandwiching its fuel unsuppliable cylinder. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel control method for a multi-cylinder engine that individually controls the amount of fuel supplied from a fuel injection valve to a plurality of cylinders, and more specifically, from a fuel injection valve for a certain cylinder among the plurality of cylinders. It relates to measures to actively reduce engine vibration when fuel supply becomes impossible.

  In general, in a multi-cylinder engine such as a diesel engine, fuel injection control (that is, fuel injection amount control and injection timing) is electrically performed in accordance with the operating state of the engine from the viewpoint of further improving drivability. An electronic fuel injection device that performs (control) is provided (see, for example, Patent Document 1).

In such an electronic fuel injection device, the amount of fuel supplied from the fuel injection valve is individually controlled for each cylinder of the engine.
Japanese Examined Patent Publication No. 4-59458

  By the way, in the multi-cylinder engine provided with the electronic fuel injection device, as shown in FIG. 7, it is impossible to supply fuel from the fuel injection valve to a certain cylinder (fourth cylinder in FIG. 7) out of the six cylinders. In order to secure the output of the engine, control is performed to increase the amount of fuel supplied from the fuel injection valve of the second cylinder located on the rear side of the combustion cycle of the fourth cylinder.

  However, control is performed to decrease the amount of fuel supplied from the fuel injection valve of the sixth cylinder located on the rear side of the combustion cycle by the amount of increase in the amount of fuel supplied from the fuel injection valve of the second cylinder. Therefore, the amount of fuel supplied from the fuel injection valve of the third cylinder located on the rear side of the combustion cycle of the sixth cylinder is increased according to the decrease in the amount of fuel supplied from the fuel injection valve of the sixth cylinder, Further, the amount of fuel supplied from the fuel injection valve of the fifth cylinder located on the rear side of the combustion cycle of the third cylinder is decreased in accordance with the increase of the amount of fuel supplied from the fuel injection valve of the third cylinder. Will be done. This is because the amount of rotation of the crankshaft is determined by recognizing, for example, two cylinders before the combustion cycle of the cylinder by supplying fuel from the fuel injection valve to each cylinder.

  For this reason, the amount of fuel supplied from the fuel injection valve of each cylinder is increased or decreased alternately to cause variation, and the vibration of the engine becomes very large.

  The present invention has been made in view of such a point, and an object of the present invention is to actively vibrate the engine when fuel supply from a fuel injection valve to a certain cylinder among a plurality of cylinders becomes impossible. It is an object of the present invention to provide a fuel control method for a multi-cylinder engine that can be reduced in an effective manner.

  In order to achieve the above object, according to the present invention, as a fuel control method for a multi-cylinder engine that individually controls the amount of fuel supplied from a fuel injection valve to a plurality of cylinders, the fuel from the fuel injection valve to the cylinder is controlled. Rotation recognition means is provided for recognizing the amount of rotation of the crankshaft rotated by the supply by a cylinder before the combustion cycle of the cylinder. Then, when fuel supply from a fuel injection valve to a certain cylinder among the plurality of cylinders becomes impossible, the amount of rotation of the crankshaft for each of at least four cylinders in which the combustion cycle continues before the combustion cycle of the cylinder is recognized. As described above, the number of target cylinders is changed by the rotation recognition means, and the intervals of the combustion cycle are uniform between the cylinders located on both sides of the combustion cycle across the cylinder to which fuel cannot be supplied. As described above, control is performed so as to stop the fuel supply of the fuel injection valve that supplies fuel to the cylinder in which the fuel cannot be supplied and the cylinder having the same combustion cycle interval.

  When the fuel supply from the fuel injection valve to a certain cylinder among the plurality of cylinders becomes impossible due to this specific matter, the number of cylinders of the target cylinder by the rotation recognition means is set to the combustion cycle before the combustion cycle of the cylinder that cannot supply fuel. Fuel supply of a fuel injection valve that changes to at least four consecutive cylinders, recognizes the amount of rotation of the crankshaft for each cylinder, and supplies fuel to cylinders whose combustion cycle intervals coincide with cylinders that cannot supply fuel The combustion cycle interval between the cylinders located on both sides before and after the combustion cycle is made uniform across the cylinder where fuel is not supplied, so that the combustion cycle before the combustion cycle of the cylinder where fuel cannot be supplied The amount of fuel supply is determined by recognizing the rotation amount of the crankshaft for each of at least four consecutive cylinders, and between the cylinders to which fuel is not supplied from the fuel injection valve Spacing baked cycle is made uniform. As a result, it is possible to actively reduce engine vibration caused by a cylinder not supplied with fuel from the fuel injection valve.

  In addition, when the supply of fuel from a fuel injection valve to a certain cylinder among a plurality of cylinders becomes impossible, if the operable region of the engine is changed in accordance with the vibration of the engine, the fuel is injected from the fuel injection valve. Variations between the combustion cycles of the cylinders that are not supplied and the cylinders that are supplied with fuel from the fuel injection valve are suppressed, and it is possible to effectively reduce engine vibration in a reasonable operating range of the engine.

  Then, when supply of fuel from the fuel injection valves to the plurality of cylinders in which the combustion cycle continues among the plurality of cylinders becomes impossible, control is performed to supply fuel from the fuel injection valves to all remaining cylinders. If this is the case, it becomes possible to secure an operable region of the engine by supplying fuel to all the remaining cylinders.

  Furthermore, the fuel injection amount from the fuel injection valve that supplies fuel to each cylinder is adjusted according to the boost pressure by the boost compensator, and fuel supply from the fuel injection valve to a certain cylinder among the plurality of cylinders is impossible When the fuel injection amount adjustment by the boost compensator is controlled, the boost pressure by the boost compensator is adjusted even if the boost pressure is reduced by the cylinder not supplied with fuel from the fuel injection valve. By canceling the adjustment of the fuel injection amount, the fuel injection amount is not suppressed as the engine output decreases. As a result, when fuel supply from a fuel injection valve to a cylinder of a plurality of cylinders becomes impossible, the engine can be operated without being limited by the fuel injection amount adjustment by the boost compensator. The area can be enlarged.

  In short, when the fuel supply from a fuel injection valve to a certain cylinder becomes impossible, at least four cylinders in which the combustion cycle continues before the combustion cycle of the cylinder incapable of supplying the fuel by the rotation recognition means To recognize the amount of rotation of the crankshaft for each cylinder, and stop the fuel supply of the fuel injection valve that supplies fuel to the cylinder whose combustion cycle interval coincides with the cylinder that cannot supply the fuel. Rotating the crankshaft of at least four cylinders in which the combustion cycle continues before the combustion cycle of the cylinder where fuel cannot be supplied by making the intervals of the combustion cycles between the cylinders located on both sides before and after the combustion cycle of the cylinder that does not perform In addition to determining the amount of fuel supplied by recognizing the amount, the intervals of the combustion cycle between cylinders not supplied with fuel from the fuel injection valve are made uniform, and the engine It is possible to actively reduce vibration.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of a common rail fuel injection system used in a multi-cylinder diesel engine according to an embodiment of the present invention.

  This common rail type fuel injection system includes a plurality of (six in this example) fuel injectors 2 mounted on each cylinder of a marine six-cylinder diesel engine 1 (hereinafter referred to as an engine). An electronic control that electronically controls the supply pump 3 that is rotationally driven by the engine 1, a common rail 5 that forms a pressure accumulating chamber that accumulates high-pressure fuel discharged from the supply pump 3, and the injector 2 and the supply pump 3 of each cylinder Unit 10 is provided.

  The injector 2 of each cylinder is connected to a high-pressure pipe (not shown) connected to the downstream end of a plurality of branch pipes (high-pressure piping paths) 16 branched from the common rail 5, and the high-pressure fuel accumulated in the common rail 5 is engineed. 1 is a fuel injection nozzle that injects fuel into the combustion chamber of each cylinder. The fuel injection from the injector 2 to the engine 1 is electronically controlled by energizing and stopping energization (ON / OFF) to an injection control solenoid valve (not shown) provided in the middle of the fuel passage in the injector 2. Is done. That is, the high pressure fuel accumulated in the common rail 5 is injected and supplied into the combustion chamber of each cylinder of the engine 1 while the injection control solenoid valve of the injector 2 of each cylinder is open.

  The supply pump 3 is driven by a well-known feed pump (not shown) that pumps up fuel in the fuel tank 9 by the pump drive shaft 12 rotating as the crankshaft 11 of the engine 1 rotates, and the pump drive shaft 12. A plunger (not shown), and a pressurizing chamber (not shown) for pressurizing the fuel by the reciprocating motion of the plunger. The supply pump 3 is a high-pressure supply pump that pressurizes the fuel sucked out by the feed pump and discharges high-pressure fuel from the discharge port to the common rail 5. An inlet metering valve 4 that changes the amount of fuel discharged from the supply pump 3 to the common rail 5 by opening and closing the fuel flow path on the inlet side of the fuel flow path to the pressurizing chamber of the supply pump 3. It is attached.

  The inlet metering valve 4 is electronically controlled by a control signal (pump drive signal) from the electronic control unit 10 via a pump drive circuit (not shown), thereby sucking fuel sucked into the pressurizing chamber of the supply pump 3. A suction valve for adjusting the amount of intake (pump suction valve), a pressure in the common rail 5 (hereinafter referred to as a common rail pressure) corresponding to the injection pressure (fuel pressure) supplied from each injector 2 to the engine 1 ) Has been made to change. The inlet metering valve 4 is a normally open type pump flow control valve (solenoid valve) that is fully opened when energization is stopped.

  The common rail 5 needs to continuously accumulate a high pressure corresponding to the injection pressure, and is connected to a discharge port of a supply pump 3 that discharges high-pressure fuel through a fuel pipe (high-pressure pipe path) 13 for that purpose. ing. The leaked fuel from the injector 2 and the leaked fuel from the supply pump 3 are returned to the fuel tank 9 via a leak pipe (low pressure passage) 14. The relief pipe (low pressure passage) 15 that relieves fuel from the common rail 5 to the fuel tank 9 has a pressure limiter 6 for releasing the pressure so that the common rail pressure does not exceed the limit accumulated pressure (limit set pressure). It is attached.

  The pressure limiter 6 is a pressure safety valve that opens when the fuel pressure in the high-pressure piping path, that is, the actual common rail pressure exceeds the limit set pressure, to keep the fuel pressure below the limit set pressure. The pressure limiter 6 includes a valve body (valve body), a ball valve (valve body) that opens and closes a valve hole formed in the valve body, a piston that operates integrally with the ball valve, a ball valve and a piston. Is provided with a spring or the like that is urged with a predetermined urging force on the side (valve closing direction) on which the valve seat is seated. The valve opening pressure of the pressure limiter 6 is determined by the seat diameter of the ball valve and the set load of the spring.

  The electronic control unit 10 includes functions such as a CPU that performs control processing and arithmetic processing, a ROM that stores various programs and data, a RAM, an input circuit, an output circuit, a power supply circuit, an injector drive circuit, and a pump drive circuit. And a microcomputer having a known structure. And the sensor signal from various sensors is comprised so that it may input into a microcomputer, after A / D-converting with an A / D converter.

  The electronic control unit 10 also determines an optimal target injection timing (injection start timing) according to the operating conditions of the engine 1 and a target injection amount (injection period) of fuel injected from the injector 2 of each cylinder to the engine 1. Each of the injection amount / injection timing determining means, the injection pulse width determining means for calculating the injector injection pulse of the injection pulse time (injection pulse width) according to the operating condition and the target injection amount of the engine 1, and the injector drive circuit Injector drive means for applying an injector injection pulse to the injection control solenoid valve of the injector 2 is provided. That is, the electronic control unit 10 sets the target based on engine operation information such as the engine rotation speed detected by the rotation speed sensor 21 (hereinafter referred to as engine rotation speed) and the accelerator opening detected by the accelerator opening sensor 22. The injection amount is calculated, and the injector injection pulse is applied to the injection control electromagnetic valve of the injector 2 of each cylinder in accordance with the injection pulse width calculated from the operating condition of the engine 1 and the target injection amount. As a result, the engine 1 is operated.

  Then, the electronic control unit 10 calculates a target common rail pressure corresponding to the optimum fuel injection pressure according to the operating conditions of the engine 1, and discharges the inlet metering valve 4 of the supply pump 3 via the pump drive circuit. It is also a quantity control means. That is, the electronic control unit 10 detects engine operation information such as the engine speed detected by the rotation speed sensor 21 and the accelerator opening detected by the accelerator opening sensor 22, and further the engine cooling detected by the cooling water temperature sensor 23. A target common rail pressure is calculated in consideration of the correction of the water temperature, and a control signal is output to the inlet metering valve 4 of the supply pump 3 in order to achieve the target common rail pressure.

  Further, the electronic control unit 10 includes a rotation of the crankshaft 11 for each cylinder in a combustion cycle that is repeated in the order of the first cylinder, the fourth cylinder, the second cylinder, the sixth cylinder, the third cylinder, and the fifth cylinder. The amount is input by the crankshaft rotation amount sensor 24. Then, as shown in FIG. 2, the electronic control unit 10, for example, determines the amount of rotation of the crankshaft 11 that is rotated by the fuel injection supply from the injector 2 to the fifth cylinder (the fuel is injected and supplied from the injector 2). Rotation recognition means 100 is provided that recognizes two or more cylinders (sixth cylinder and third cylinder in FIG. 2) before the combustion cycle of the fifth cylinder). As shown in FIG. 3, the rotation recognizing means 100 is configured such that when the fuel injection from the injector 2 to a certain cylinder (fourth cylinder in the figure) among the six cylinders becomes impossible, the cylinder (fourth cylinder) The cylinder number of the target cylinder is changed from 2 cylinders to 6 cylinders so that the rotation amounts of the crankshafts of all 6 cylinders in which the combustion cycle continues before the combustion cycle of) are recognized. In this case, the detection that the fuel injection from the injector 2 to a certain cylinder among the six cylinders has become impossible is detected by the fuel pressure detection sensor 25 provided in the common rail 5, and this fuel pressure detection sensor. According to No. 25, even if fuel is supplied from the injector 2 to an arbitrary cylinder, the detection is performed when the common rail pressure does not decrease due to the injection.

  When the electronic control unit 10 becomes unable to supply fuel from the injector 2 to one of the six cylinders (fourth cylinder in FIG. 3), the fuel injection is performed as shown in FIG. Fuel injection so that the intervals of the combustion cycle (interval of one cylinder) are uniform between the first cylinder and the second cylinder located on both sides of the combustion cycle across the fourth cylinder that cannot be supplied Control is performed to stop the fuel injection of the injector 2 that injects and supplies fuel to the sixth cylinder and the fifth cylinder whose combustion cycle intervals coincide with the fourth cylinder that cannot be supplied. At this time, the amount of rotation of the crankshaft 11 of the four cylinders (including cylinders to which fuel is not injected and supplied) before the combustion cycle of the cylinder to which fuel is injected and supplied from the injector 2 is recognized. The number of target cylinders by the rotation recognition means 100 is changed to four cylinders. Further, the fuel injection amount from the injector 2 for the three cylinders is approximately doubled as compared with the case where the fuel injection from the injector 2 is performed for all the six cylinders, and the engine output is maintained.

  In addition, the electronic control unit 10 controls the vibration range of the engine 1 when the fuel injection from the injector 2 to a certain cylinder (fourth cylinder in FIG. 3) out of the six cylinders becomes impossible. It is changed according to. In this case, as shown in FIG. 5, two characteristics (characteristics indicated by a one-dot chain line and a two-dot chain line in the figure) of the fuel injection amount of the injector 2 for each cylinder with respect to the rotational speed, which are determined in advance by the vibration of the engine 1, are obtained. Is selected accordingly. The characteristic indicated by the solid line in FIG. 5 indicates a normal case in which fuel injection from the injector 2 for all cylinders is performed without hindrance. Further, as shown in FIG. 6, each characteristic can be obtained from the characteristic of the engine torque with respect to the engine speed.

  In addition, when the fuel injection from the injector 2 to two or more cylinders in which the combustion cycle continues among the plurality of cylinders becomes impossible, the electronic control unit 10 applies all of the remaining cylinders from the injector 2. Control is performed to perform fuel injection supply. For example, when the fuel injection from the injector 2 to the two cylinders, the first cylinder and the fourth cylinder, in which the combustion cycle continues, becomes impossible, the remaining second cylinder, sixth cylinder, third cylinder, and fifth cylinder Control is performed so that fuel is supplied from the injector 2 to all the cylinders.

  Further, the fuel injection amount of the injector 2 that supplies fuel to each cylinder is adjusted according to the boost pressure by the boost compensator. The electronic control unit 10 performs control so as to cancel the fuel injection amount adjustment by the boost compensator when fuel injection from the injector 2 to a certain cylinder among the six cylinders becomes impossible.

  Therefore, in the above embodiment, when the fuel injection from the injector 2 to a certain cylinder (for example, the fourth cylinder) of the six cylinders becomes impossible, the number of cylinders of the target cylinder by the rotation recognition unit 100 is injected. Change to all six cylinders in which the combustion cycle continues before the combustion cycle of the fourth cylinder which cannot be supplied, recognize the amount of rotation of the crankshaft 11 for each cylinder, Between the cylinders positioned on both sides before and after the combustion cycle, the fuel injection of the injector 2 for injecting and supplying the fuel to the sixth cylinder and the fifth cylinder with the same combustion cycle interval is stopped, and the cylinder not injecting and supplying the fuel is sandwiched Since the intervals of the combustion cycles in the cylinder are made uniform, the combustion cycles of all six cylinders in which the combustion cycles continue before the combustion cycle of the cylinders to which fuel injection cannot be supplied are all On the injection quantity of fuel to recognize the amount of rotation of the rank shaft 11 is determined, the fuel from the injector 2 becomes uniform spacing of the combustion cycles between cylinders not injected and supplied. Thereby, the vibration of the engine 1 caused by the cylinder to which fuel is not supplied from the injector 2 can be actively reduced.

  When the fuel injection from the injector 2 to a certain cylinder among the six cylinders becomes impossible, two fuel injection amounts of the injector 2 for each cylinder with respect to the rotational speed, which are determined in advance by the vibration of the engine 1, are determined. Since the operable region of the engine 1 is changed according to the characteristics (characteristics indicated by the one-dot chain line and the two-dot chain line in FIG. 5), the fuel in which fuel is not supplied from the injector 2 and the fuel from the injector 2 are supplied. Variations between the combustion cycles with the cylinders are suppressed, and vibrations of the engine 1 can be effectively reduced in a reasonable operating range of the engine 1.

  When the fuel injection from the injector 2 to two or more cylinders in which the combustion cycle continues among the six cylinders becomes impossible, the fuel injection from the injector 2 is supplied to all the remaining cylinders. Thus, the operable region of the engine 1 can be ensured by supplying fuel to all the remaining cylinders.

  Furthermore, when the fuel injection from the injector 2 to a certain cylinder among the six cylinders becomes impossible, the fuel injection amount adjustment according to the boost pressure by the boost compensator is controlled to be canceled. Even if the boost pressure is reduced by the cylinder to which fuel is not supplied from 2, the fuel injection amount is not suppressed as the output of the engine 1 is reduced by releasing the fuel injection amount adjustment according to the boost pressure by the boost compensator. . Thus, when the fuel injection from the injector 2 to a certain cylinder among the six cylinders becomes impossible, the output of the engine 1 is not limited by the fuel injection amount adjustment by the boost compensator. The operable range can be expanded.

  In addition, this invention is not limited to the said embodiment, The other various modifications are included. For example, in the above-described embodiment, a 6-cylinder engine is used as a multi-cylinder engine, but any engine can be applied to any marine engine as long as it is an even-cylinder engine having 4 or more cylinders.

1 is a schematic configuration diagram showing an overall configuration of a common rail fuel injection system applied to a marine 6-cylinder engine according to an embodiment of the present invention. It is a characteristic view which shows the fuel injection quantity of each cylinder of the combustion cycle in a normal state. It is a characteristic view which shows the fuel injection quantity of each cylinder of a combustion cycle in the state where the injection supply of the fuel from an injector became impossible with respect to a certain cylinder. Fuel injection amount of each cylinder in the combustion cycle in a state where the fuel injection of the injector for injecting and supplying fuel to the sixth cylinder and the fifth cylinder whose combustion cycle interval coincides with the fourth cylinder incapable of supplying fuel injection FIG. FIG. 6 is a characteristic diagram showing a fuel injection amount characteristic with respect to an engine speed in a normal state and a state where fuel injection of an injector for each cylinder is stopped. FIG. 5 is a characteristic diagram showing engine torque characteristics with respect to engine speed in a normal state and in a state where fuel injection of an injector for each cylinder is stopped. It is a characteristic figure which shows the fuel injection quantity of each cylinder of a combustion cycle in the state where the fuel injection supply from the injector became impossible with respect to the cylinder with the engine concerning a prior art example.

Explanation of symbols

1 6-cylinder diesel engine (multi-cylinder engine)
11 Crankshaft 100 Rotation Recognition Means 2 Injector (Fuel Injection Valve)

Claims (4)

A fuel control method for a multi-cylinder engine that individually controls the amount of fuel supplied from a fuel injection valve to a plurality of cylinders,
Rotation recognition means for recognizing the amount of rotation of the crankshaft rotated by supplying fuel from the fuel injection valve to the cylinder by a cylinder before the combustion cycle of the cylinder
When the supply of fuel from a fuel injection valve to a certain cylinder among a plurality of cylinders becomes impossible, the amount of rotation of the crankshaft for at least four cylinders in which the combustion cycle continues before the combustion cycle of the cylinder is recognized. As described above, the number of target cylinders by the rotation recognition means is changed, and the intervals of the combustion cycle are uniform between the cylinders located on both sides of the combustion cycle across the cylinder to which fuel cannot be supplied. A fuel control method for a multi-cylinder engine, characterized in that control is performed to stop fuel supply of a fuel injection valve that supplies fuel to a cylinder whose combustion cycle interval coincides with a cylinder that cannot supply fuel. The fuel control method for a multi-cylinder engine according to claim 1,
Fuel control of a multi-cylinder engine, wherein when the fuel supply from a fuel injection valve to a certain cylinder among a plurality of cylinders becomes impossible, the operable region of the engine is changed according to engine vibration Method. In the fuel control method for a multi-cylinder engine according to claim 1 or 2,
When supply of fuel from the fuel injection valve to a plurality of cylinders in which the combustion cycle of the plurality of cylinders continues is disabled, control is performed so that fuel is supplied from the fuel injection valves to all remaining cylinders. A fuel control method for a multi-cylinder engine. The fuel control method for a multi-cylinder engine according to any one of claims 1 to 3,
The fuel injection valve that supplies fuel to each cylinder has its fuel injection amount adjusted according to the boost pressure from the boost compensator.
Fuel control for a multi-cylinder engine, wherein the fuel injection amount adjustment by the boost compensator is canceled when the fuel supply from the fuel injection valve to a certain cylinder among the plurality of cylinders becomes impossible Method.

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