JP2006046187A - Control device of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to obtain the good restartability without making the fuel concentration downstream of a throttle valve too high even when oil-tight leakage occurs in an injector. <P>SOLUTION: When an injection switch 22 is turned OFF from ON, it is judged as an engine stop to open the throttle valve 7. As a result, even when oil-tight leakage occurs in the injector 12, vaporized gas of the fuel produced by oil-tight leakage can be diffused through the throttle valve 7 to the upstream side, so that the fuel concentration downstream of the throttle valve 7 is not made too high, and the good restartability can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine control device that opens a throttle valve when an engine is stopped and diffuses fuel vaporized gas downstream of the throttle valve upstream.

  Conventionally, as an injector for injecting a predetermined amount of fuel into a combustion chamber of an engine, a multi-point injection (MPI) type injector arranged in an intake manifold communicating with each cylinder and directing an injection direction to an intake valve, A single point injection (SPI) type injector disposed downstream of a throttle valve is known.

  In any injector, the accumulated fuel is injected by opening the injector, so if the oil tightness decreases due to mass production variation, aging deterioration, etc., immediately after the engine stops, In some cases, so-called oil-tight leakage occurs where fuel leaks from the injection hole.

  When oil-tight leak occurs from the injector, the fuel concentration downstream of the throttle valve increases, and depending on the amount of oil-tight leak, the fuel concentration downstream of the throttle valve may be below the flammable limit. If the fuel concentration downstream of the throttle valve falls below the flammable limit, the air-fuel ratio in the combustion chamber becomes overrich until the air-fuel mixture with high fuel concentration is scavenged at the time of engine start, and good startability can be obtained. In addition to inconveniences that cannot be made, there is an inconvenience that steps are likely to occur in the rotation increase after the engine is started.

As a countermeasure, for example, in Patent Document 1 (Japanese Utility Model Publication No. 6-87656), a collector is formed downstream of the throttle valve, and the inside of the collector is divided into a first container and a second container through a partition plate. The partition plate is provided with a communicating part that communicates both containers, and an open / close valve is provided at the communicating part. When the engine is stopped and when the engine is started, the open / close valve is opened so that both containers communicate with each other. A technique is disclosed in which the fuel is diffused in both containers to avoid over-rich air-fuel ratio at the time of starting.
Japanese Utility Model Publication No. 6-87656

  In the technique disclosed in Patent Document 1, the communication part opened in the partition plate is opened while the engine is stopped to diffuse the fuel leaked from the injector. However, the communication part is opened. However, it takes about 1.5 to 2 hours until the fuel is uniformly diffused in both containers.

  Therefore, when the engine is restarted within about 1.5 to 2 hours after the engine is stopped, the air-fuel ratio of a specific cylinder tends to be overrich, and a good restartability cannot be obtained.

  As a countermeasure, it is necessary to provide a new space for increasing the intake system volume at the place partitioned by the open / close valve, which not only complicates the structure but also cannot be applied to existing engines. There is a problem that lacks sex.

  In view of the above circumstances, the present invention does not over-concentrate the fuel concentration downstream of the throttle valve even when an oil-tight leak occurs in the injector, and restarts relatively early after the engine stops. It is another object of the present invention to provide an engine control device capable of obtaining good restartability.

  In order to achieve the above object, an engine control apparatus according to the present invention includes an air cleaner disposed upstream of an intake manifold communicating with an intake port, a throttle valve disposed between the intake manifold and the air cleaner, and the throttle An engine having an injector disposed downstream of a valve includes engine stop detection means for detecting engine stop after engine operation has started, and valve opening means for opening the throttle valve, and the engine control unit includes the engine A valve opening signal is output to the valve opening means when engine stop is detected by the stop detection means.

  According to the present invention, since the throttle valve is opened when engine stop is detected, the fuel vaporized gas downstream of the intake valve is supplied to the upstream side of the throttle valve even when oil-tight leakage occurs in the injector. The fuel concentration does not become excessive, and good startability can be obtained even if the engine is restarted relatively early after the engine is stopped.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overall configuration diagram centering on an intake system of an engine.

  Reference numeral 1 in the figure denotes a multi-cylinder engine, and in this embodiment, a horizontally opposed engine. The left and right intake manifolds 2 connected to the intake port 1a formed for each cylinder of the engine 1 are gathered on the upstream side, and the throttle body 3 communicates with the upstream of the gathering portion 2a. Further, an intake duct 4 communicates with the upstream side of the throttle body 3, and an air cleaner 5 is provided at the uppermost stream of the intake duct 4.

  Resonator chambers 5 a and 5 b are respectively formed in the air intake side of the air cleaner 5 and in the middle of the intake duct 4, and a midway having a bent portion 4 a of the intake duct 4 is inserted into the intake chamber 6. The intake chamber 6 and the intake duct 4 are communicated with each other through a plurality of communication ports 4b formed in the bent portion 4a.

  The intake chamber 6 reduces intake noise particularly when the engine 1 is in a low and medium speed range. That is, relatively gentle intake air flowing through the intake duct 4 when the engine 1 is in the middle / low speed region flows into the intake chamber 6 from the communication port 4b when passing through the bent portion 4a of the intake duct 4, The intake sound is silenced by the expansion action of the intake air, and the intake pulsation is reduced by the resonance action of the intake chamber 6.

  The throttle body 3 is provided with an electronic control throttle valve 7 constituting an electronic control throttle system (ETC). The electronically controlled throttle valve 7 has its valve opening controlled by an electronically controlled throttle motor 8 serving as a valve opening means. The electronic control throttle valve 7 is provided with a throttle position sensor 9, and the throttle position sensor 9 detects the actual valve opening of the electronic control throttle valve 7. Furthermore, an MPI injector 12 is disposed in the intake port 1a to direct the injection direction toward the intake valve 11 side. The injector may be an SPI injector disposed downstream of the electronic control throttle valve 7.

  On the other hand, the left and right front exhaust pipes 13 connected to the exhaust port 1b of the engine 1 are gathered on the downstream side, the downstream of this gathering part is connected to the rear exhaust pipe 14, and the muffler 15 is placed downstream of the rear exhaust pipe 14 Is communicated. Further, a front catalyst 16 is interposed on the upstream side of the front exhaust pipe 13 and a rear catalyst 17 is interposed on the downstream collecting portion.

  Further, a front air-fuel ratio sensor 18 and a rear O2 sensor 19 are disposed on the upstream side and the downstream side of the front catalyst 16, respectively.

  The fuel injection control for the injector 12 and the throttle opening control for the electronic control throttle motor 8 are performed by an engine control unit (engine ECU) 21. The engine ECU 21 includes a computer such as a microcomputer including a CPU, a ROM, a RAM, a constant voltage circuit that supplies a constant voltage to each unit, a delay timer, and the like.

  Further, on the input side of the engine ECU 21, as sensors for detecting the operating state of the engine, a throttle position sensor 9, a front air-fuel ratio sensor 18, a rear O2 sensor 19, and an intake air amount that detects an intake air amount (not shown). A sensor, a rotation speed sensor for detecting the engine rotation speed, an accelerator position sensor for detecting the depression amount of the accelerator pedal, and the like are connected, and a battery 23 is connected via an ignition switch 22 which is an example of an engine stop detection means. ing. Further, the battery 23 is connected to a constant voltage circuit (not shown) of the engine ECU 21 via a relay contact of the power relay 24.

  On the other hand, the electronic control throttle motor 8, the injector 12 and the like are connected to the output side of the engine ECU 21, and the relay coil of the power relay 24 is connected.

  When the ignition switch 22 is turned on, start-up power is supplied from the battery 23 to the engine ECU 21. The engine ECU 21 excites the relay coil of the power relay 24 with the supplied starting power source. Then, the power relay 24 is turned on, and the driving power from the battery 23 is supplied to each part via a constant voltage circuit (not shown) in the engine ECU 21. On the other hand, when the ignition switch 22 is turned off, a delay timer built in the engine ECU 21 is operated, and after the set time has elapsed, the energization of the relay coil of the power relay 24 is cut off and the system is stopped.

  The engine ECU 21 performs various controls such as air-fuel ratio control based on information output from each sensor, and outputs a drive signal corresponding to the accelerator opening detected by the accelerator position sensor to the electronic control throttle motor 8. The opening degree of the electronically controlled throttle valve 7 is controlled.

  In the air-fuel ratio control, the air-fuel ratio is set based on the actual air-fuel ratio in the exhaust gas detected by the front air-fuel ratio sensor 18 with respect to the fuel injection amount set based on the engine speed, the intake air amount, etc. The main feedback control is performed so that the target air-fuel ratio is detected, and the sub-feedback control for correcting the target air-fuel ratio based on the air-fuel ratio detected by the rear O2 sensor 19 is performed to set and set the actual fuel injection amount to be output to the injector 12 A fuel injection signal corresponding to the fuel injection amount is output to the injector 12 of the corresponding cylinder at a predetermined timing.

  By the way, the injector 12 has a structure in which the fuel accumulated in a fuel delivery line (not shown) is injected into the intake port 1a by opening the injection hole. Even if the injection hole of the injector 12 is closed immediately after the engine stops, a slight oil-tight leak occurs. In the air-fuel ratio control, even if an oil-tight leak occurs in the injector 12, it is not considered as a correction term. Therefore, if restarting is performed as it is, the air-fuel ratio becomes overrich. Startability deteriorates.

  The engine ECU 21 according to the present embodiment outputs a signal for opening the electronically controlled throttle valve 7 to the electronically controlled throttle motor 8 for a certain period of time after the engine is stopped, and the fuel that leaks from the injector 12 and vaporizes the fuel. 7 Diffuse to the upstream side.

  Specifically, the throttle valve opening control after engine stop processed by the engine ECU 21 is executed in accordance with the throttle valve opening control routine after engine stop shown in FIG.

  When the ignition switch 22 is turned on, the starting power is supplied from the battery 23 to the engine ECU 21. The engine ECU 21 excites the relay coil of the power relay 24 with the supplied starting power source to turn on the power relay 24. Then, the driving power is supplied from the battery 23 to the constant voltage circuit in the engine ECU 21 through the relay contact of the power relay 24, and the constant voltage power is supplied to each part from the constant voltage circuit.

  On the other hand, this routine is started when the ignition switch 22 is turned on. First, in step S1, whether or not the engine 1 is stopped after the engine operation is determined by checking whether or not the ignition switch 22 is turned off. When the switch 22 is ON, it waits until it is turned OFF.

  When the ignition switch 22 is turned off, it is determined that the engine is stopped, and the process proceeds to step S23. After the timer count value T of the delay timer is cleared (T ← 0), the output value of the throttle position sensor 9 is set in step S3. Based on this, it is checked whether or not the electronically controlled throttle valve (THV) 9 is in the valve open state. If it is in the valve open state, the process proceeds to step S5. If it is in the valve closed state, the process branches to step S4. Then, a valve opening signal is output to the electronic control throttle motor 8, the electronic control throttle valve (THV) 9 is opened, and the process proceeds to step S5.

  In this case, the determination in step S3 may not be performed, and the process may proceed from step S2 to step S4 to open the electronic control throttle valve 7 uniformly.

  In step S5, the timer count value T of the delay timer is incremented (T ← T + 1), and the process proceeds to step S6 to check whether or not the timer count value T has reached a set time T1 (for example, a value corresponding to 5 min). If not reached yet (T ≦ T1), the process returns to step S5 to increment the timer count value T.

  When the timer count value T reaches the set time T1 (T> T1), the process proceeds to step S7, the power supply to the electronic control throttle motor 8 is cut off, and the electronic control throttle valve (THV) 9 is closed. .

  Next, the process proceeds to step S8, the power supply to the relay coil of the power relay 24 is cut off, the power relay 24 is turned off, the system is stopped, and the routine is terminated.

  Thus, in this embodiment, when the ignition switch 22 is turned off, the engine ECU 21 is not immediately stopped, the system is started only for the set time T1, and the electronic control throttle valve 7 is opened during that time. As a result, the intake valve 11 to the vicinity of the element downstream of the air cleaner 5 are in communication.

  As a result, even if an oil tight leak occurs in the injector 12 when the engine 1 is stopped, the vaporized fuel remains in the intake duct 4, the resonator chamber 5 b, the intake chamber 6, the throttle body 3 on the element downstream side of the air cleaner 5. Because the fuel is diffused early to a relatively large volume of the intake manifold 2 and the intake port 1a, the fuel concentration does not become excessive even if the engine is restarted relatively early after the engine is stopped. Startability can be obtained. Therefore, it is possible to reduce the start time required for restart and to reduce exhaust emissions.

  Further, when the intake valve and the exhaust valve of any cylinder stop in a valve overlap state, even if the exhaust gas in the front exhaust pipe 13 flows backward to the intake manifold 2 side, it communicates to the vicinity of the element downstream of the air cleaner 5. Therefore, exhaust gas can be diffused. As a result, a significant decrease in the oxygen concentration in the intake manifold 2 can be prevented, and even when the engine is stopped in a valve overlap state, a good startability can be obtained and exhaust emissions can be reduced. Can be realized.

  In addition, since the throttle valve 7 is always opened when the engine is stopped, the throttle valve can be prevented from sticking.

  Further, in the electronically controlled throttle system (ETC), when the engine is stopped, the electronically controlled throttle valve 7 is opened once, so that the initialization of the electronically controlled throttle valve 7 when the ignition switch 22 is turned on can be accelerated. It can be completed and the start-up time can be shortened.

  Further, in this embodiment, the space upstream of the electronic control throttle valve 7 is used as it is to diffuse the fuel vapor generated by the oil-tight leak, so it is necessary to secure a space for a new volume increase. Therefore, it can be applied to an existing engine as it is, and high versatility can be obtained.

  The opening degree of the electronically controlled throttle valve 7 detected in step S3 or the opening degree of the electronically controlled throttle valve 7 set in step S4 may be fully open, but the fuel concentration in the intake manifold 2 when the engine is stopped However, the opening may be reduced to a level that does not affect the start, and need not be fully open.

  The present invention can also be applied to an engine not equipped with an electronically controlled throttle system (ETC). That is, even in a normal throttle valve in which the accelerator pedal and the throttle valve are mechanically linked, an engine equipped with a throttle control device such as a cruise control device uses a throttle control actuator, Open the throttle valve.

  Further, the intake valve is not limited to the throttle valve, and may be an idle speed control (ISC) valve interposed in a throttle bypass passage that bypasses the throttle valve, for example, and the ISC valve is opened when the engine is stopped. Thus, the vaporized fuel gas generated by the oil-tight leak is diffused upstream through the throttle bypass passage.

Overall configuration diagram centering on the engine intake system Flow chart showing throttle opening control routine after engine stop

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Intake port, 1b ... Exhaust port, 2 ... Intake manifold, 2a ... Collecting part, 3 ... Throttle body, 4 ... Intake duct, 4a ... Bending part, 4b ... Communication port, 5 ... Air cleaner, 5a, 5 ... Resonator chamber, 6 ... Intake chamber, 7 ... Electronically controlled throttle valve, 8 ... Electronically controlled throttle motor, 9 ... Throttle position sensor, 11 ... Intake valve, 12 ... Injector, 21 ... Engine control unit, 22 ... Ignition switch

Agent Patent Attorney Susumu Ito

Claims (3)

An air cleaner is disposed upstream of the intake manifold communicating with the intake port,
A throttle valve is disposed between the intake manifold and the air cleaner;
In an engine in which an injector is disposed downstream of the throttle valve,
Engine stop detection means for detecting engine stop after engine operation has started;
Opening means for opening the throttle valve,
The engine control unit, wherein the engine control unit outputs a valve opening signal to the valve opening means when the engine stop detecting means detects the engine stop.   2. The engine control apparatus according to claim 1, wherein the engine stop detection means is an ignition switch, and determines that the engine is stopped when the ignition switch is switched from an on state to an off state.   The opening degree of the throttle valve by the valve opening signal output from the engine control unit is such that at least fuel vaporized gas due to oil-tight leakage from the injector is diffused upstream of the throttle valve, and downstream of the throttle valve. 3. The engine control apparatus according to claim 1, wherein the fuel concentration is set to a value that can be lowered to a level that does not affect engine start.

Images