JP2005240559A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To operate an internal combustion engine at a proper air-fuel ratio from the start of the engine. <P>SOLUTION: This controller comprises a means for detecting the start of the engine beforehand, a means for calculating the amount of a fuel according to the amount of air in an intake manifold, a means for promoting the evaporation of the fuel by heating, a means for feeding the fuel and air into a combustion chamber, and an engine control means for controlling these means according to the operating conditions of the engine. The air-fuel ratio in an intake tube is set to a proper value from the start of the engine to promote the evaporation of the fuel by a heater. Thus, since a mixture in the intake manifold can be formed in a proper air-fuel ratio, exhaust gas level can be reduced from the start of the engine. Also, since an increased amount of fuel after the start of the engine can be reduced, a fuel cost can be improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to engine fuel control, and more particularly, to an air-fuel ratio control method at engine startup.

  In order to reduce the environmental load in recent years, it is required to reduce the exhaust gas level from the engine, and it is required to control the air-fuel ratio in the combustion chamber to an appropriate range.

  Conventionally, since the fuel amount at the time of starting the engine is injected as a value corresponding to the engine water temperature, the air-fuel ratio is not controlled.

  However, in order to reduce the exhaust gas level, it is necessary to reduce the exhaust gas component at the time of starting the engine in order to reduce the exhaust gas component at the time of starting the engine.

  Further, since the temperature of the intake manifold is low when the engine is started, the fuel is not completely vaporized, and the amount of fuel depending on the evaporation rate enters the combustion chamber, making it difficult to accurately control the air-fuel ratio in the combustion chamber. In addition, it takes time for the exhaust gas sensor to be activated, and air-fuel ratio control according to the exhaust gas sensor cannot be performed at the start. In order to improve the evaporation rate, there is an example in which a device for heating and vaporizing the fuel supplied to the intake manifold is added. For example, there is a fuel vaporization promoting device described in JP-A-2003-206833.

JP 2003-206833 A

  Accordingly, an object of the present invention is to ensure startability and reduce exhaust gas components by sending fuel and air that are matched to an accurate air-fuel ratio to the combustion chamber when the engine is started.

  In order to solve the above problems, the present invention provides means for sending fuel and air into the combustion chamber without depending on the water temperature or the intake air temperature at the time of starting the engine.

  First, a means for injecting a fuel amount corresponding to the amount of air in the intake manifold is prepared, and a fuel heating means for promoting fuel vaporization and sending it to the combustion chamber as much as possible is prepared.

  Furthermore, in order to prepare fuel and air from the start of the engine, a means for detecting the timing for starting the engine is combined.

  According to the present invention, since the air-fuel ratio in the intake manifold can be set to an appropriate air-fuel ratio, the exhaust level can be reduced from when the engine is started. Moreover, since the fuel increase after engine starting can be reduced, there exists an effect which can improve a fuel consumption. FIG. 16 shows the experimental result data of the present invention. In the conventional engine start (MPI), a large amount of engine-out HC component is discharged at the time of engine start, but it has been confirmed that the HC component can be reduced by improving the startability according to the present invention.

  Even if the engine restart is repeated, excess fuel does not remain in the intake manifold, so that the fuel amount at the time of restart does not become overrich. Therefore, restart may be facilitated.

  FIG. 1 shows the configuration of an internal combustion engine according to the present invention.

The internal combustion engine 100 includes a fuel injection valve 101, a spark plug 102, an ignition coil 103, a throttle 104, a water temperature sensor 110, a crank angle sensor 111, a cam angle sensor 112, a throttle position sensor 113, an intake pipe pressure sensor 114, or intake air. A flow meter 115, a linear air-fuel ratio sensor 116, a catalyst 118, and a rear O ₂ sensor are attached after the catalyst and are connected to the engine control device 120.

  The fuel is transported from the fuel tank 125 by the fuel pump 117, and a constant fuel pressure is set by the pressure regulator 119.

  An intake air temperature sensor 121 and an exhaust gas temperature sensor 122 are attached as engine control parameters.

  The intake manifold is provided with a heater and a secondary fuel injection valve.

  FIG. 2 shows an outline of the engine control device.

  In the engine control device, a CPU 401 that performs numerical / logical operations, a ROM 402 that stores programs and data executed by the CPU, a RAM 403 that temporarily stores data, an A / D converter 404 that captures an analog voltage from a sensor. , A digital input circuit 405 for capturing a switch indicating an operating state, a time interval of a pulse signal or a pulse input circuit 406 for counting the number of pulses within a predetermined time, and an actuator (not shown) being turned on based on a calculation result of the CPU The digital output circuit 407, the timer setting output circuit 408, and the communication circuit 409 that turn off can output the data in the engine control device 120 to the outside or change the internal state by a communication command from the outside.

  In the present invention, as shown in FIG. 3, means for detecting engine start in advance, means for calculating the amount of fuel according to the amount of air in the intake manifold, means for heating the fuel to promote vaporization, fuel and air It comprises means for sending to the combustion chamber and engine control means for controlling each of the means according to the operating state of the engine.

  First, as shown in FIG. 4, the engine control means divides the control state according to the engine water temperature, intake air temperature, intake air amount, time after engine start, and engine speed. For example, when the engine water temperature or the intake air temperature is lower than a predetermined value, the following control is performed. Further, as a condition for stopping the following control and shifting the normal engine control, the predetermined engine speed or the elapsed time after the start is used as a threshold value, and then the normal engine control is shifted.

  In addition, as a means for detecting engine start and generating a trigger, for example, a start-only switch, a door opening / closing switch, a driver's load switch, a brake switch, an accelerator pedal switch, a clutch switch, and the like are taken in. Control is started with a change from OFF or OFF to ON as a trigger.

  In the first control state, the heater installed near the fuel injection valve is energized to heat the heater.

  In the second control state, a fuel amount corresponding to the air amount in the intake manifold is injected toward the heater.

  The third control state creates an air flow to promote fuel vaporization.

  Thereafter, the engine is switched to normal engine control after a predetermined engine speed or time has elapsed after starting.

As an example of promoting vaporization, in the first embodiment, fuel is injected toward the heater, and vaporization is promoted by the heat generated by the heater. For example, when the apparatus shown in FIG. 5 in which the heater and the fuel injection valve are integrated is used, the heater can be easily heated. PTC (Positive Temperature) as a heater
If Coefficient) is used, the temperature rise stops at a predetermined temperature even when the heater energization is set to 100%. If the surface temperature of the PTC is equal to or higher than the vaporization temperature, the heater can be energized by switching with a relay.

  As shown in FIG. 5, when the heater surface temperature is low, the heat generation amount is large, and the heat generation amount decreases as the surface temperature increases. Electrically, as the heater surface temperature increases, the heater resistance increases and the temperature rises until the amount of heat generated is balanced with the amount of heat released. When the heater resistance is increased, the amount of heat generation is reduced, so that the temperature does not reach a predetermined temperature.

  In the second embodiment, an air-fuel mixture forming pump is further provided in the intake manifold to mix the fuel and air in the intake manifold. For example, as shown in FIG. 6, a vaporized fuel sub-passage is prepared and circulated by a pump. Instead of circulation, a method of introducing air from the outside may be used.

  In the third embodiment, a heater is prepared inside the fuel injection valve, a heater chamber is provided, and a fuel injection valve into which fuel heated in the heater chamber is injected is used. For example, as shown in FIG. 7, the fuel is heated and vaporized in the heater chamber, and a part of the vaporized fuel becomes bubbles to increase the pressure in the heater chamber, and it is possible to inject with the bubble pressure.

  In the first embodiment, an average voltage applied to the heater is set according to the engine water temperature or the intake air temperature, and the heater temperature is raised to the fuel vaporization temperature. In the case of using the PTC, even if the heater energization is set to 100%, the temperature rise stops at a predetermined temperature, so that it is not necessary to set the average voltage.

  At the same time as the heater temperature rises above the vaporization temperature in the first control state, the fuel pump is activated to raise the fuel pressure to a predetermined value.

  On the contrary, it is possible to vaporize the fuel by starting the fuel pump first, injecting the fuel into the heater, and then heating the heater. In this case, since the heater directly heats the fuel, the heater power increases slightly, but vaporization is promoted, so that the energization time can be made relatively short.

  When the volume of the intake manifold is M and the air-fuel ratio is λ, the required fuel amount Qf is Qf∝M / λ, and the fuel injection valve is driven in proportion to the fuel amount Qf.

  Thereafter, air is passed through the air passage to mix with the fuel adhering to the heater.

  In order to flow air, a mixing air pump installed in the intake manifold is driven.

  Alternatively, the exhaust valve is closed and the intake valve is opened for several revolutions when the starter drive is started. return.

  After several times of mixing promotion, normal engine start is performed.

  In the second embodiment, another fuel injection valve is also added to the bypass passage, and fuel at the time of starting is injected from the auxiliary fuel injection valve.

  In this case, the amount of fuel injected from the auxiliary fuel injection valve is not the volume of the intake manifold, but the amount of fuel proportional to the bypass passage volume. Furthermore, in order to promote vaporization, it is also possible to send air using a compressed air injector dedicated to the bypass passage. When the control valve of the bypass passage is opened and vaporized by the bypass air, the fuel injection amount from the auxiliary fuel injection valve is set not only to the volume of the bypass passage but also to the fuel amount that takes into account even after the engine starts.

  After the engine is started, the (main) fuel injection valve and the auxiliary fuel injection valve inject a fuel amount that becomes a predetermined air-fuel ratio.

  In the third embodiment, the fuel injection valve and the heater are integrated to heat the fuel and promote vaporization. The heater is installed between the fuel injection valve and the fuel passage or during the injection from the fuel injection valve to the intake manifold.

  Further, in the case of using an integrated fuel injection valve and a heater for the auxiliary fuel injection valve installed in the bypass passage, a method of injecting bubbles by generating a heater instead of the needle valve in the fuel injection valve is also possible. . In this case, since the fuel can be injected even when the fuel pressure is almost zero, the startability of the engine can be improved.

  FIG. 8 shows a timing chart of the first embodiment.

  A control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on (501).

  Thereafter, the heater relay and the fuel pump relay are turned on (502).

  Further, the fuel injection valve is driven for a predetermined time (503). If necessary, fuel injection is repeated a predetermined number of times.

  The air mixing pump is driven (504).

  Thereafter, the starter relay is turned on to start the engine.

  After the engine rotation is detected, the air mixing pump is stopped (505).

  Thereafter, the heater is turned off after a predetermined time elapses or after a predetermined engine speed is reached.

  A predetermined delay time is set between the operations.

  It takes time for the heat capacity of the heater and its surroundings until the heater temperature reaches a predetermined temperature after the heater is energized. For this reason, the delay time is set according to the intake air temperature or the water temperature.

  FIG. 9 shows a flowchart of the first embodiment.

  The following operations are controlled by a task activated every 10 ms, for example.

  A control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on (601).

  Thereafter, the heater relay and the fuel pump relay are turned on (602).

  Further, the fuel injection valve is driven for a predetermined time (603). If necessary, fuel injection is repeated a predetermined number of times.

  The air mixing pump is driven (604).

  Thereafter, the starter relay is turned on to start the engine.

  After the engine rotation is detected, the air mixing pump is stopped (605).

  Thereafter, the heater is turned off after a predetermined time elapses or after a predetermined engine speed is reached.

  A predetermined delay time is set between the operations.

  In the first embodiment, when mixing is promoted without using an air mixing pump, the ignition signal is stopped, the intake valve is opened, the exhaust valve is closed, and the starter relay is turned on. Thereafter, after the engine rotates several times, an ignition signal is applied at a normal timing to return to the normal engine control from the state (505) or (605).

  FIG. 10 shows a timing chart of the second embodiment.

  First, close the main throttle of the intake manifold.

  Next, a control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on ( 701).

  Thereafter, the heater relay and the fuel pump relay are turned on (702).

  Further, the auxiliary fuel injection valve is driven for a predetermined time (703). If necessary, fuel injection is repeated a predetermined number of times.

  Thereafter, the compressed air injector is driven (704).

  Thereafter, the starter relay is turned on to start the engine.

  When the driver is depressing the accelerator pedal, the throttle is opened so that the throttle opening degree is in accordance with the depression amount.

Then, after a predetermined time has elapsed or a predetermined engine speed has been reached, the heater is turned off (705).

  A predetermined delay time is set between the operations.

  FIG. 11 shows a flowchart of the second embodiment.

  The following operations are controlled by a task activated every 10 ms, for example.

  First, close the main throttle of the intake manifold.

  Next, a control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on ( 801).

  Thereafter, the heater relay and the fuel pump relay are turned on (802).

  Further, the auxiliary fuel injection valve is driven for a predetermined time (803). If necessary, fuel injection is repeated a predetermined number of times.

  Thereafter, the compressed air injector is driven (804).

  Thereafter, the starter relay is turned on to start the engine.

  When the driver is depressing the accelerator pedal, the throttle is opened so that the throttle opening degree is in accordance with the depression amount.

Thereafter, the heater is turned off after a predetermined time has elapsed or a predetermined engine speed has been reached (805).

  A predetermined delay time is set between the operations.

  FIG. 12 shows a timing chart of the third embodiment.

  First, close the main throttle of the intake manifold.

  Next, a control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on ( 901).

  Thereafter, the fuel pump relay is turned on (902).

  Further, the heater of the auxiliary fuel injection valve is driven for a predetermined time (903). If necessary, voltage application to the heater is repeated a predetermined number of times.

  Thereafter, the starter relay is turned on to start the engine.

  When the driver is depressing the accelerator pedal, the throttle is opened so that the throttle opening degree is in accordance with the depression amount.

  Thereafter, the heater is turned off after a predetermined time elapses or after a predetermined engine speed is reached.

  A predetermined delay time is set between the operations.

  FIG. 13 shows a flowchart of the third embodiment.

  The following operations are controlled by a task activated every 10 ms, for example.

  First, close the main throttle of the intake manifold.

  Next, a control start trigger is set when a switch for detecting opening / closing of a door or a load on a driver's seat, a switch for detecting depression of a brake or a clutch, or a parking neutral switch for an AT vehicle is turned on ( 1001).

  Thereafter, the fuel pump relay is turned on (1002).

  Further, the heater of the auxiliary fuel injection valve is driven for a predetermined time (1003). If necessary, voltage application to the heater is repeated a predetermined number of times.

  Thereafter, the starter relay is turned on to start the engine.

  When the driver is depressing the accelerator pedal, the throttle is opened so that the throttle opening degree is in accordance with the depression amount.

  Thereafter, the heater is turned off after a predetermined time elapses or after a predetermined engine speed is reached.

  A predetermined delay time is set between the operations.

  In the first to third embodiments, as shown in FIG. 14, the outlet of the vaporized fuel passage is prepared in the vicinity of the intake valve so that the vaporized fuel is taken into the combustion chamber in a short time, Since the air-fuel mixture with a predetermined air-fuel ratio is introduced into the combustion chamber when the engine is started, there is no need to inject extra fuel to compensate for the insufficient vaporization in the past, and the startability is improved. It is possible to reduce exhaust components at the start.

  Next, heater self-diagnosis will be described with reference to FIG.

  Case 1 is a case where the heater current is zero even when the heater output is turned on and the heater wiring drop voltage is also zero, and the heater or the heater wiring may be disconnected. In this case, the voltage applied to the heater Is zero, so the heater will not overheat.

  In case 2, when the heater output is turned on and the heater current is zero and the heater wiring drop voltage is not zero, the heater output terminal may be shorted to the ground. In this case, the heater control is turned off.

  In case 3, if the heater current does not become zero even when the heater output is turned off, a failure of the output transistor is considered.

  Case 4 is a case where the heater current becomes excessive when the heater output is turned on, and the heater output is shorted to VB, and the heater control is turned off.

  In case 5, when the heater output is turned on, the heater current is not zero, but when the heater output is too small, the heater resistance value has increased, and it is determined that the heater itself has deteriorated.

  If the heater is PTC, the heater resistance value and the temperature are inversely proportional, so the voltage and current applied to the heater are monitored to calculate the heater resistance value, and the resistance value is within a predetermined range. It is also possible to make a diagnosis of the heater by determining whether or not.

  When it is determined that the heater has failed or deteriorated, a warning lamp is turned on to prompt the driver to repair the heater, and heater control at the time of starting the engine is stopped.

The engine block diagram of one Example of this invention. Engine control device block diagram. Control means explanatory drawing of this invention. FIG. 3 is an explanatory diagram of input / output of the present invention. A device that integrates a heater and a fuel injection valve. Schematic diagram of air-fuel mixture circulation in the intake manifold. The fuel-injection-valve schematic which incorporated the heater. The flowchart of 1st Example. The timing chart of 1st Example. The flowchart of 2nd Example. The timing chart of 2nd Example. The flowchart of 3rd Example. The timing chart of 3rd Example. Explanatory drawing of a sub channel | path. Explanatory drawing of self-diagnosis of a heater. The effect explanatory view of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Internal combustion engine main body, 101 ... Fuel injection valve, 102 ... Spark plug, 103 ... Ignition coil, 104 ... Throttle, 105 ... ISC valve, 106 ... Air cleaner, 107 ... Engine block, 108 ... Intake intake pipe, 109 ... Exhaust 110, water temperature sensor, 111, crank angle sensor, 112, cam angle sensor, 113, throttle position sensor,
DESCRIPTION OF SYMBOLS 114 ... Intake pipe pressure sensor, 115 ... Intake air amount meter, 116 ... Linear air fuel ratio sensor, 117 ... Fuel pump and fuel pump relay, 119 ... Pressure regulator, 120 ... Engine control apparatus, 121 ... Intake temperature sensor, 122 ... Exhaust Temperature sensor, 123 ... catalyst, 124 ... secondary air pump, 125 ... fuel tank, 126 ... fuel bypass valve.

Claims (11)

  A fuel injection valve provided in an intake pipe of an internal combustion engine, and a heater provided in the vicinity of the fuel injection valve or in the vicinity of the fuel injection valve, and the fuel injection valve and the heater are A control device for an internal combustion engine, characterized by controlling.   2. The control apparatus for an internal combustion engine according to claim 1, wherein the information related to engine start detects an operating state by using an operation at a preparation stage for starting the engine as a trigger.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the information related to the engine start includes opening / closing of a door, a change in a load on a driver's seat, and information related to the engine start is a change in a start-only switch of the control system. , A control device for an internal combustion engine, characterized in that it is one of a change of a clutch, a brake, and a parking neutral switch.   4. The control apparatus for an internal combustion engine according to claim 1, wherein an amount of electric power to be supplied to the heater is set according to a water temperature or an intake air temperature.   5. The control apparatus for an internal combustion engine according to claim 4, wherein the heater is a PTC and the surface temperature of the PTC is equal to or higher than the vaporization temperature of the fuel.   6. The control apparatus for an internal combustion engine according to claim 1, wherein the ignition signal is stopped for a predetermined rotation or a predetermined time when the engine is started.   7. The control apparatus for an internal combustion engine according to claim 1, wherein opening and closing of the exhaust valve or the intake valve is stopped for a predetermined rotation or a predetermined time when the engine is started. .   4. The control apparatus for an internal combustion engine according to claim 1, further comprising a pump for introducing air into the intake manifold, wherein the fuel injection valve, the heater, and the air introduction according to information related to engine start. A control device for an internal combustion engine, characterized by operating a pump.   4. The control apparatus for an internal combustion engine according to claim 1, further comprising a pump for circulating the air-fuel mixture in the intake manifold, and a fuel injection valve, a heater, and the air-fuel mixture pump according to information related to engine start. A control device for an internal combustion engine characterized by operating the engine.   4. The control apparatus for an internal combustion engine according to claim 1, wherein a secondary fuel injection valve is installed in a bypass passage of the intake manifold, and fuel at the time of starting the engine is injected from the secondary fuel injection valve. A control device for an internal combustion engine.   11. The control apparatus for an internal combustion engine according to claim 1, wherein temperature control is stopped when an abnormality is detected in a voltage or current value applied to the heater means. apparatus.

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