JP2005083216A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection timing control device capable of injecting fuel at optimum injection timing corresponding to the operating state of an engine without heating a mixed gas. <P>SOLUTION: This control device for an internal combustion engine has a fuel injection valve 501a for supplying fuel by injecting fuel into an intake passage of the internal combustion engine, and a control unit 100 which is a fuel injection timing control means for controlling the fuel injection timing of the fuel injection valve. The control unit 100 corrects the injection timing to the advance side or delay side in proportion to the bad degree of volatility of fuel based on fuel properties showing the propriety of volatility of fuel in use, and sets fuel injection timing according to engine water temperature detected by a water temperature sensor 517. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to a public control device for an internal combustion engine for optimizing the fuel injection timing in accordance with the properties of the fuel used.

  In a general internal combustion engine, when the temperature is low, the fuel vaporization state is deteriorated and the engine startability is deteriorated. For example, in an engine using heavy gasoline, startability at low temperatures deteriorates because the heavy components of gasoline are difficult to vaporize. Further, in an engine that uses an alcohol-mixed fuel as an alternative fuel in addition to conventional gasoline, if the alcohol concentration of the fuel is high, the low-temperature startability deteriorates.

  Therefore, for example, as described in JP-A-8-277734, in a fuel injection method for an engine provided with a heater for vaporizing the fuel injected into the intake system, based on the engine speed and the fuel injection amount. There is known a control method for correcting the fuel injection timing set in accordance with the fuel vaporization time obtained according to the energization state of the heater so that the vaporization of the injected fuel is completed before the intake valve is opened. In this control method, the fuel injection timing is set based on the engine speed and the fuel injection amount, and the vaporization time of the injected fuel is obtained according to the energization state of the heater for vaporizing the injected fuel. Therefore, if the heater is energized, the fuel vaporization ability will be fully utilized and the heater will be If it is not energized, a sufficient fuel vaporization time can be secured, and the mixed state with the intake air can be improved and supplied to the combustion chamber. Therefore, it is possible to improve exhaust gas emission by improving startability and combustion stability.

JP-A-8-277734

  However, in the start-up injection control method described in JP-A-8-277734, when the fuel mixture is further heated after the fuel injection timing is advanced, the fuel mixture vaporized by heating is used. As a result of adhering to the inside of the low-temperature intake pipe during the stay until the cylinder intake timing, there has been a problem that the startability and the combustion stability are reduced.

  An object of the present invention is to provide a fuel injection timing control device that can inject fuel at an optimal injection timing according to the operating state of an engine without heating the air-fuel mixture.

(1) To achieve the above object, the present invention provides a fuel injection valve that injects fuel into an intake passage of an internal combustion engine and supplies the fuel, and a fuel injection timing control that controls the fuel injection timing of the fuel injection valve. The fuel injection timing control means is configured to advance the injection timing on the more advanced side as the fuel volatility becomes worse based on the fuel property indicating whether the volatility of the fuel in use is good or bad. Alternatively, the fuel injection timing is set according to the engine water temperature while correcting to the retard side.
With this configuration, the fuel can be injected at an optimal injection timing according to the operating state of the engine without heating the air-fuel mixture.

  (2) In the above (1), preferably, the fuel injection timing control means measures an elapsed time after the previous engine stop and checks the state of the fuel tank when starting the engine. The fuel property determination is performed when the set time has elapsed after the engine is stopped or when at least one of the fuel supply determination conditions is satisfied.

  According to the present invention, fuel can be injected at an optimal injection timing according to the operating state of the engine without heating the air-fuel mixture.

Hereinafter, the configuration and operation of an internal combustion engine control apparatus according to an embodiment of the present invention will be described with reference to FIGS.
First, the system configuration of an internal combustion engine system using the control device for a multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 1 is a system configuration diagram of an internal combustion engine system using a control device for a multi-cylinder internal combustion engine according to an embodiment of the present invention.

  In the case of a four-cylinder engine, for example, the internal combustion engine 10 is an in-line four-cylinder internal combustion engine in which four cylinders # 1, # 2, # 3, and # 4 are provided. The air to be taken in by the cylinder 507 is taken into the intake pipe 505 from the inlet 522a of the air cleaner 502, passes through the air meter 503, and the throttle in which the electric throttle valve 505a for controlling the air flow rate driven by the motor 526 is accommodated. Pass the body and enter the collector 506. Here, the intake air is distributed to the intake passages 501 connected to the cylinders # 1, # 2, # 3, and # 4 of the internal combustion engine 10, and is introduced into the combustion chamber 507c above the piston 507a via the intake valve 501a. It is burned. The negative pressure between the intake air 505 is detected by the negative pressure sensor 56.

  On the other hand, fuel such as gasoline is pressurized by the fuel pump 51 from the fuel tank 514 and is provided adjacent to the downstream end of the intake passage 501 of each cylinder # 1, # 2, # 3, # 4 via the piping system. The fuel injection valve 54 is guided. The fuel pressure is adjusted by the regulator 52. A signal indicating the air flow rate is output from the air flow meter 503 and input to the control unit 100. Further, a throttle sensor 504 for detecting the opening of the throttle valve 505 a is attached to the throttle body, and its output is also input to the control unit 100.

  Ignition of the air-fuel mixture in the combustion chamber 507c is performed by energizing the ignition coil 522 from the control unit 100, cutting off the energization, applying a high voltage to the spark plug 508, and giving ignition energy to the air-fuel mixture. The The ignited air-fuel mixture is discharged to the exhaust passage 519 through the exhaust valve 510c. The exhaust passage 519 is provided with an air-fuel ratio sensor 518 that detects the air-fuel ratio in the exhaust gas, and a catalyst 520 that purifies the exhaust gas.

  A water temperature sensor provided in the cylinder block 5 detects the cooling water temperature of the engine 10 and supplies it to the control unit 100 instead of an electric signal. An A / F sensor 31 is disposed in the exhaust passage 29, and an output signal of the sensor 31 is also supplied to the control unit 100. Further, a catalyst 32 for removing harmful components in the exhaust gas is attached to the exhaust passage 29.

  On the other hand, the crankshaft 516a is provided with a crank angle sensor 516b for detecting the rotation reference position and the angular position from the rotation reference position. The camshaft 510d is additionally provided with a cylinder discrimination sensor 511 that generates a discrimination signal at least once during one rotation of the camshaft 510d. The crank angle sensor 516b may be attached to the camshaft 510d. The cylinder 507 is provided with a water temperature sensor 517.

Next, the configuration of the control unit 100 of the control device for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 2 is a block diagram of the control unit 100 of the control device for the multi-cylinder internal combustion engine according to the embodiment of the present invention.

  The control unit 100 includes a ROM 120 in which function data and various control programs are stored, an MPU 110 that executes arithmetic processing based on the various programs stored in the ROM 120, calculation results in the MPU 110, data input from the outside, and the like. A RAM 130 that temporarily stores data and a backup RAM that stores data stored in the RAM 130 when power supply to the control unit 100 is stopped are provided. The MPU 110, the ROM 120, the RAM 130, and the backup RAM are connected to each other via a bidirectional path, and are also connected to an input / output circuit 140 configured by an I / O LSI including an A / D converter. A signal (pulse) from the crank angle sensor 516 b and a signal (pulse) from the cylinder discrimination sensor 511 are supplied to the input circuit 140, and the fuel injection valve 54 and the ignition coil 522 are connected to the output circuit 140.

  The control unit 100 takes as input signals from various sensors that detect the operating state of the engine, executes predetermined calculation processing, and outputs various drive control signals calculated as calculation results to the above-described fuel injection. The fuel is supplied to the valve 54 and the ignition coil 522 at a predetermined timing, and fuel injection control and ignition control are executed.

  Furthermore, the control apparatus for an internal combustion engine of the present embodiment is characterized in that the above-described configuration determines the volatility of the fuel in use, and aims to improve exhaust emission by realizing the optimum fuel injection timing according to the property. have.

  In this case, the fuel injection timing at which optimum exhaust emission is obtained varies depending on the properties of the fuel used, specifically, as described below, depending on the properties of the fuel. Hydrocarbon is an unburned component in the exhaust gas, and the content in the exhaust gas shows a lower value as the fuel supplied into the combustion chamber completely burns. Therefore, in order to obtain good exhaust emission, it is necessary to improve the flammability of the fuel supplied to the combustion chamber. In that case, in addition to good exhaust emission, improvement in fuel consumption of the internal combustion engine is also realized. Can do.

  Here, it is known that there is a correlation between the combustibility of the fuel supplied to the combustion chamber of the internal combustion engine and the timing at which the fuel is injected into the intake pipe. Fuel injection at such a timing that it is sufficiently vaporized after being injected into the combustion chamber and combusted until it burns, and at the time of valve overlap that occurs during the transition from the exhaust process to the intake process. Timing is set.

  However, the fuel properties distributed in the market are not necessarily constant, and heavy fuels that are less volatile than standard fuels or light fuels that are excellent in volatility may be used. In this case, it is clear that there is a difference in the time required for the injected fuel to reach an appropriate vaporized state. A longer time is ensured for a heavy fuel, and a shorter time is required for a light fuel. It will be enough.

  Even when standard fuel is used, if the engine coolant temperature is low, volatility may be inferior to that of heavy fuel. On the other hand, when the engine coolant temperature is high, it may be as volatile as light fuel.

  Therefore, in order to always ensure the optimum exhaust emission, ensure high combustion efficiency and obtain excellent fuel consumption characteristics, it is necessary to set the fuel injection timing in consideration of such differences in fuel properties. Specifically, the injection timing is corrected to the advance side or the retard side as the volatility of the fuel is worse. Further, the fuel injection timing is corrected according to the water temperature. When the injection timing is corrected to the advance side or the retard side, at least the maximum delay side injection timing set to close the fuel injection valve after the engine intake valve is opened, and at least the engine Depending on the state of judgment, the volatility of the fuel in use is continuously determined between the maximum early injection timing set so that the fuel injection valve is closed before the intake valve opens. Change the injection timing. In addition, the fuel volatilization characteristic value is calculated between the maximum delay side injection timing and the maximum early side injection timing, and based on the calculated volatilization characteristic value, the lower the volatilization characteristic value, the slower the fuel injection valve is closed, The higher the volatility characteristic value, the sooner the fuel injection valve is closed.

Next, the fuel injection timing setting map for setting the fuel injection timing used in the control apparatus for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 3 is an explanatory diagram of a fuel injection timing setting map for setting the fuel injection timing used in the control device for the multi-cylinder internal combustion engine according to the embodiment of the present invention.

  The fuel injection timing map is composed of a normal use temperature range (referred to as constant temperature) map M1, a low temperature map M2 that is a minus temperature, and a cryogenic temperature map M3 that is a lower temperature than the low temperature.

  When the fuel injection timing at start-up stores the result of the fuel property determination in the previous operation, the fuel injection timing at start-up is determined according to the past fuel property determination result and the current engine coolant temperature value To do. On the other hand, when the engine unit does not memorize the result of the fuel property determination in the previous operation, only based on the currently detected value of the engine coolant temperature without using the past fuel property determination result, Determine the fuel injection timing.

Next, the fuel injection timing correction table used in the control device for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 4 is an explanatory diagram of a fuel injection timing correction table used in the control device for a multi-cylinder internal combustion engine according to one embodiment of the present invention.

  As described above, the fuel injection timing is determined based on the current engine coolant temperature. Therefore, as shown in FIG. 4, the correction coefficient for each water temperature is held by the correction table. By using this correction table to obtain a correction coefficient for the current water temperature and correcting the fuel injection timing, it is possible to start in a short time even when heavy fuel is used. In addition, regarding the fuel property determination method, a method known in various documents or the like is adopted.

Next, a method for determining the fuel injection timing in the control apparatus for a multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 5 is a flowchart showing a method of determining fuel injection timing in the control apparatus for a multi-cylinder internal combustion engine according to one embodiment of the present invention.

  The processing routine shown in FIG. 5 is started by a routine that occurs at a predetermined timing or every scheduled job, and is executed by the engine control unit 100.

  First, in step S100, the engine control unit 100 detects the engine coolant temperature. Next, in step S110, the fuel injection timing is set based on the engine coolant temperature detected in step S100.

  Next, in step S120, it is determined whether or not the fuel property has already been determined. If the fuel property has not been determined, the process proceeds directly to step S140, and fuel injection is performed in step S140. If the fuel property is determined in step S120, the process proceeds to step S130, the fuel injection timing is corrected in accordance with the fuel property, and the process proceeds to step S140, where fuel injection is performed.

Next, the fuel property determination method in the control apparatus for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 6 is a flowchart showing a fuel property determination method in the control apparatus for a multi-cylinder internal combustion engine according to the embodiment of the present invention.

  As shown in FIG. 6, the fuel property determination processing routine in step S <b> 120 is started at a predetermined timing or a predetermined job timing of the engine control unit and executed by the engine control unit 100.

  First, in step S200, the engine control unit 100 determines whether or not the backup storage device is normal. If the backup is faulty, the process proceeds to step S250, where fuel property determination is performed. Various known methods can be used as the method for determining the fuel property, but the fuel volatilization characteristic value is calculated based on the operating condition of the internal combustion engine, and the volatilization of the fuel in use is calculated based on the calculated volatilization characteristic value. Judge the quality of the sex.

  Next, in step S200, if the backup storage device is normal, the process proceeds to step S210, and it is determined whether a predetermined time has elapsed since the previous key off. When a predetermined time has elapsed since the previous key off, the process proceeds to step S250, and fuel property determination is performed.

  If it is determined in step S210 that the predetermined time has not elapsed since the previous key off, the process proceeds to step S220, and it is determined whether the fuel supply is determined. If it is determined in step S220 that the fuel has been supplied, the process proceeds to step S250 where the fuel property is determined.

  If it is not determined in step S220 that the fuel has been supplied, the process proceeds to step S230, where it is determined whether the fuel property has not been determined. If the fuel property has not been determined, the process proceeds to step S250, where the fuel property is determined.

  If the fuel property determination has been completed in step S230, the process proceeds to step S240, where the fuel property determination is performed in each operation state of the internal combustion engine, compared with the backed-up past fuel property determination results, and if the fuel property determination is different, The value backed up in the latest fuel property judgment is updated. Here, the operating state of the internal combustion engine includes at least one of the rotational speed, the load, the temperature of the internal combustion engine, and the amount of deposit accumulated in the intake passage.

  Next, the backup method of the fuel property state and the method of measuring the Key Off time in the control apparatus for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a fuel property state backup method and Key Off time measurement method in the control apparatus for a multi-cylinder internal combustion engine according to the embodiment of the present invention.

  The processing routine shown in FIG. 7 is started by a routine that occurs at a predetermined timing or every scheduled job, and is executed by the engine control unit 100.

  First, in step S300, the engine control unit 100 determines whether or not processing is performed at the time of Key Off. If it is not determined in step S300 that the process is Key Off, this process ends.

  Next, if it is determined in step S300 that the processing is being performed at the time of Key Off, it is determined in step S310 whether the backup storage device is normal. If the backup storage device is not normal, this processing ends. .

  Next, if it is determined in step S310 that the backup storage device is normal, the process proceeds to step S320, where it is determined whether the fuel property has been determined. If the fuel property has not been determined, the process ends. .

  Next, in step S320, if the fuel property is determined, the process proceeds to step S330, the determination result of the fuel property is stored in the backup storage device, and the process proceeds to step S340.

  Next, in step S340, the key off start time is stored so that the time when the key is turned on next time can be known.

  After storing the key off start time, the process proceeds to step S350, and the fuel tank information at the time of key off is stored so that it can be determined whether or not the fuel has been refueled when the key is turned on next time. After the fuel information is stored in step S350, this process ends.

Next, the fuel volatilization characteristics by the control device for the multi-cylinder internal combustion engine according to the present embodiment will be described with reference to FIG.
FIG. 8 is an explanatory diagram of fuel volatilization characteristics by the control device for a multi-cylinder internal combustion engine according to one embodiment of the present invention. The horizontal axis of FIG. 8 shows the output of the water temperature sensor, and the vertical axis shows the volatilization characteristic value of the fuel.

  FIG. 8 shows the fuel volatilization characteristics until the injected fuel is carried to the combustion chamber in this embodiment. In the conventional fuel injection system, as indicated by the solid line X0, the volatilization characteristics deteriorated as the temperature became lower, regardless of the properties of heavy and light fuels.

  On the other hand, according to the present embodiment, the fuel vaporization time is increased by correcting the fuel injection timing to the advance side on the low temperature side as shown by the solid line X2 with respect to the volatile characteristic value X1 of the normal fuel. Can do. Even with heavy fuel with poor volatility, as shown by the solid line X3, it is possible to take a long vaporization time before entering the combustion chamber. can do.

As described above, in this embodiment, in order to grasp the volatilization characteristics of the fuel supplied to the internal combustion engine, the fuel properties are stored and the fuel property values are obtained. Then, based on the cooling water temperature of the internal combustion engine, an operating state-volatility characteristic map of the internal combustion engine is searched to obtain a basic correction amount for fuel injection. Further, the fuel injection can be performed at the optimal injection timing according to the engine operating state, which is corrected based on the volatilization characteristic value. As a result, it is possible to reduce the startability deterioration associated with the decrease in the volatility of the fuel.

1 is a system configuration diagram of an internal combustion engine system using a control device for a multi-cylinder internal combustion engine according to an embodiment of the present invention. 1 is a block diagram of a control unit 100 of a control device for a multi-cylinder internal combustion engine according to an embodiment of the present invention. It is explanatory drawing of the fuel-injection timing setting map for setting the fuel-injection timing used for the control apparatus of the multicylinder internal combustion engine by one Embodiment of this invention. It is explanatory drawing of the fuel injection timing correction table used for the control apparatus of the multicylinder internal combustion engine by one Embodiment of this invention. It is a flowchart which shows the determination method of the fuel injection timing in the control apparatus of the multicylinder internal combustion engine by one Embodiment of this invention. 4 is a flowchart showing a fuel property determination method in the control apparatus for a multi-cylinder internal combustion engine according to the embodiment of the present invention. 3 is a flowchart showing a fuel property state backup method and a Key Off time measurement method in the control apparatus for a multi-cylinder internal combustion engine according to an embodiment of the present invention. It is explanatory drawing of the fuel volatilization characteristic by the control apparatus of the multicylinder internal combustion engine by one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Control unit 510a ... Fuel injection valve 517 ... Water temperature sensor

Claims (2)

In a control device for an internal combustion engine having a fuel injection valve that injects fuel into an intake passage of the internal combustion engine and supplies the fuel, and a fuel injection timing control means for controlling the fuel injection timing of the fuel injection valve,
The fuel injection timing control means corrects the injection timing to the advance side or the retard side as the volatility of the fuel is worse based on the fuel property indicating whether the volatility of the fuel in use is good or not, and A control apparatus for an internal combustion engine, characterized in that fuel injection timing is set according to engine water temperature. The control apparatus for an internal combustion engine according to claim 1,
The fuel injection timing control means measures the elapsed time after the previous engine stop at the time of engine start, checks the state of the fuel tank, and determines whether or not the fuel has been refueled for a set time after the engine stops. A control apparatus for an internal combustion engine, wherein fuel property determination is performed when at least one of the conditions is satisfied.

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