JP2009002164A - Control device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an engine from stopping while in a valve overlapping state where both an intake valve and an exhaust valve are open, to avoid unburned gas remaining in an exhaust system from flowing back into an intake system, and to improve startability of the engine at the next start in a control device for engine. <P>SOLUTION: A control means is equipped with a throttle opening control means for regulating the throttle opening amount of a throttle valve capable of regulating an air amount taken in by the engine by a command from an engine control means, and an engine rotation stop control means for increasing the throttle opening regulated by the throttle opening control means to more than a control start time opening of a fuel stop control means when the engine rotational speed detected by an engine rotational speed detecting means is less than a set rotational speed after fuel supply stop control is executed by the fuel stop control means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an engine control device, and more particularly to an engine control device that performs electronic throttle control.

In the vehicle engine, the control means (ECU) stops the supply of fuel when the ignition signal is switched from on to off, and engine control means for controlling the engine based on various detection signals from each signal detection means. There is a fuel stop control means for controlling, and an engine control device for so-called electronic throttle control in which the throttle opening is electronically controlled by the control means.
In this electronic throttle control, the throttle opening is arbitrarily fixed from when the ignition signal is turned off until the engine is stopped, thereby scavenging the unburned gas in the intake system and stabilizing the next start of the engine.

2. Description of the Related Art Conventionally, a control device for an internal combustion engine maintains a throttle valve at a predetermined opening degree when the internal combustion engine is stopped, quickly balances the pressure in the intake manifold to the atmospheric pressure, and enhances the exhaust gas supply effect. There is one that prevents gas backflow and ensures restartability.
In the engine starter, an engine that is automatically stopped during idle operation is started in response to a restart request, and the piston stop position is set while scavenging the burned gas from each cylinder of the engine that rotates by inertia after the fuel cut. There is something to control.
An internal combustion engine stop control method and an internal combustion engine suitable for executing the method, wherein one of the throttle valve and the gas metering system is opened at least once during the stop operation until the internal combustion engine stops. is there.
JP 2005-291120 A JP 2005-155549 A JP 2004-162707 A

Conventionally, in an engine control device, the crank TOP position (valve where both the intake valve and the exhaust valve are open) is balanced by the balance between the crank inertia until the engine is stopped and the mechanical loss of the engine (mechanical loss). The engine may stop at the overlap position.
In this way, when the engine stops at the crank TOP position, as shown in FIG. 6, the unburned gas in the exhaust system flows back to the intake system due to valve overlap, and the oxygen concentration in the intake system decreases, and the next time There was an inconvenience that the startability of the engine was extremely deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an engine control device that prevents the engine from stopping when both the intake valve and the exhaust valve are open.

  The present invention includes engine control means for controlling the engine based on various detection signals from each signal detection means, and fuel stop control means for stopping supply of fuel when the ignition signal is switched from on to off. In the engine control apparatus provided with the control means, the engine speed detecting means for detecting the engine speed of the engine is provided, and the control means is configured to detect the amount of air taken into the engine in response to a command from the engine control means. The throttle opening degree control means for adjusting the throttle opening degree of the throttle valve capable of adjusting the engine speed, and the engine speed detected by the engine speed detection means after the fuel supply stop control is carried out by the fuel stop control means If it is less than the set speed, the throttle opening adjusted by the throttle opening control means Characterized in that it comprises an engine stop control means for increasing than the control start opening at start of control of the fuel stop control means.

  The engine control apparatus according to the present invention prevents the engine from stopping when both the intake valve and the exhaust valve are open, prevents the unburned gas in the exhaust system from flowing back to the intake system, and restarts the engine. Startability can be improved.

The purpose of this invention is to prevent the engine from stopping when both the intake valve and the exhaust valve are open, and the throttle opening between the time when the ignition signal is switched from on to off until the engine stops. This is achieved by changing
Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

1 to 3 show a first embodiment of the present invention.
In FIG. 1, reference numeral 1 is an engine control device, 2 is an in-vehicle multi-cylinder engine (4 cylinders: # 1 to # 4), 3 is an intake passage of an intake system of the engine 2, and 4 is an exhaust system of the engine 2. This is an exhaust passage.
The engine 2 is provided with an injector 5 for injecting fuel and an ignition coil 6 connected to an ignition plug.
In the intake passage 3, a throttle body 8 and an air cleaner 9 including a throttle valve 7 are disposed in order from the engine 2 side. The throttle valve 7 is opened and closed by electronic throttle control by a control means 12 described later.
A catalytic converter 10 and a muffler 11 are arranged in the exhaust passage 4 sequentially from the engine 2 side.

The engine control device 1 is provided with a control means (electronic control unit: ECU) 12. The control unit 12 includes an input unit 13 and an output unit 14.
The input unit 13 of the control means 12 functions as an engine speed detecting means for detecting the engine speed (NE) by detecting the rotation of the crankshaft of the engine 1 as each signal detecting means for detecting various detection signals. A crank angle sensor 15, a cam angle sensor 16 for detecting the cam angle of the engine 1, an engine water temperature sensor 17 for detecting the engine water temperature of the engine 1, and a throttle opening sensor 18 for detecting the throttle opening of the throttle valve 7. An air flow meter 19 for detecting the intake air flow rate in the intake passage 3 between the throttle body 8 and the air cleaner 9, an intake air temperature sensor 20 for detecting the intake air temperature, and an ignition switch (IG) 21 for switching the ignition signal on or off communicate with each other. is doing.
An injector 5, an ignition coil 6, and a throttle valve 7 that are operated by each control signal are in communication with the output unit 14 of the control means 12.

The control means 12 includes a central processing unit (CPU) 22.
The control means 12 includes an engine control means 23 for controlling the engine 1 based on various detection signals from the signal detection means, and a fuel for stopping and controlling the supply of fuel when the ignition signal is switched from on to off. A stop control means 24, a throttle opening control means 25 for adjusting the throttle opening amount of the throttle valve 7 that can adjust the amount of air taken into the engine 1 according to a command from the engine control means 23, and a fuel stop control means 24 When the engine speed (NE) detected by the crank angle sensor 15 as the engine speed detecting means after the fuel supply stop control is performed is less than the set speed (B), the throttle opening degree control means 25 The throttle opening adjusted by the control is increased from the control start opening (A) at the start of control of the fuel stop control means 24. And a engine stop control means 26 for.
The engine rotation stop control means 26 increases the set opening degree (A) that is increased from the opening degree (A) at the start of control until the holding time (D) set so as to increase as the engine water temperature increases. C), and maintain this throttle opening.

The above control start opening (A) will be described. As shown in FIG. 3, the control start opening (A) is determined by the engine speed after a predetermined time has elapsed from when the ignition switch 21 is turned off (time t1). Is the value at the time of fuel supply stop control (time t2) at which the pressure starts to decrease.
The above set rotational speed (B) will be described. As shown in FIG. 3, in order to avoid the engine 2 from stopping at the crank TOP position (valve overlap position) (time t5), “compressed air UP "Brake of" is the point. That is, it is necessary to open the throttle valve 7 so that a large amount of air enters in the intake stroke of the cylinder that stops last (= the point where the in-cylinder pressure in FIG. 3 is highest). Since there is a response delay of the throttle opening, the specific value of the set rotational speed (B) is changed depending on the model of the engine 2. For example, in the case of an engine of a certain model, it is preferable that the set rotational speed (B) is MT (with manual transmission) = 600 rpm and AT (with automatic transmission) = 650 rpm. Originally, it may be set by the crank angle from when the ignition switch 21 is turned off. However, since the engine speed is also updated every 180 ° CA, the start condition of the set speed (B) is set. Incidentally, as a starting condition for the set rotational speed (B), in addition to the set rotational speed (B), it can be dealt with by a crank angle from the ignition switch 21 being turned off. It can be set.
Further, the setting opening degree (C) of the throttle opening will be described. Since there is an air amount necessary for braking the piston of the engine 2, the request varies depending on the engine 2. However, the amount of intake in one cycle is limited depending on the displacement of the engine 2, and it is not necessary to fully open the throttle opening (for example, it is sufficient to open about 50 deg with respect to 86 deg of fully opened). For example, in the case of an engine of a certain model, the optimum range of the set opening degree (C) is preferably MT = 20 deg to 40 deg and AT = 10 deg to 30 deg. The difference in MT and AT requirements is the difference in crank inertia force depending on the presence or absence of a torque converter. Since the engine 2 is stopped earlier at the AT after the ignition switch 21 is turned off, the brake is applied (= the amount of air is increased) and the brake amount (= the amount of air) becomes smaller. Here, the set opening degree (C) has a relationship of fully closed ≦ C ≦ fully opened.
Further, the holding time (D) will be described. When the engine water temperature is low, the engine oil temperature is low, and the mechanical loss (mechanical loss) of the engine 2 is large, so that the brake is easily applied. Therefore, since the amount of air for braking may be small, the holding time (D) is set short when the engine water temperature is low, and long when the engine water temperature is high. It should be noted that the amount of air for braking must be put in, so it is not good if the holding time (D) is too short. The holding time (D) when the engine 2 is completely warmed is preferably, for example, 100 to 200 ms.

Next, the operation of the first embodiment will be described based on the flowchart of FIG. 2 and the time chart of FIG.
As shown in FIG. 2, when the program of the control means 12 is started (step A01), it is first determined whether or not the ignition switch 21 is turned off (step A02). If this step A02 is NO, Continue judgment.
When this step A02 is YES, the ignition switch 21 is turned off (indicated by time t1 in FIG. 3), the fuel supply is stopped, the engine speed starts to decrease, and the throttle opening is further set to the ignition. The initial control opening degree (A) when the switch 21 is turned off is set (indicated by time t2 in FIG. 3) (step A03). This control opening degree (A) is one of throttle opening conditions.
Then, it is determined whether or not the engine speed (NE) is less than the set speed (B) (step A04). If this step A04 is NO, this determination is continued. The set speed (B) is an engine speed condition.
When this step A04 is YES, the engine speed (NE) is less than the set speed (B) (indicated by time t3 in FIG. 3), and the throttle opening is increased from the control start opening (A). In order to increase the intake air amount, the predetermined opening time (C) is maintained and maintained for a predetermined holding time (D) (step A05). The set opening degree (C) is one of throttle opening conditions, and has a relationship of fully closed ≦ C ≦ fully open. The holding time (D) is the throttle opening holding time (indicated by time t3 to t4 in FIG. 3), and can be set for each engine water temperature. The engine water temperature is set short on the low side, while the engine water temperature is Is set longer on the high side.
When the holding time (D) elapses (indicated by time t4 in FIG. 3), the throttle opening is returned to the control start opening (A) (step A06), and the engine 2 is stopped (time in FIG. 3). (indicated by t5) (step A07), the program is terminated (step A08).

That is, in this embodiment, the throttle opening is changed so that the throttle opening from the time when the ignition switch 21 is turned off to the stop of the engine 2 is largely opened for a certain holding time (D). However, the throttle opening is changed not immediately after the ignition switch 21 is turned off, but when the engine speed is less than the set speed (B). This is for avoiding this problem because if the throttle opening is increased immediately after the ignition switch 21 is turned off, the vibration of the engine 2 is increased and worsened. The holding time (D) is switched for each engine water temperature.
When the engine 2 stops at the crank TOP position, the number of rotations of the crankshaft is determined from when the ignition switch 21 is turned off until the engine 2 is stopped, and before the compression top dead center (compression process) Always stop.
When the engine speed falls below the set speed (B), the throttle opening is greatly changed by a certain holding time (D) (or closed until fully closed), so that a large amount of air is sucked (or shut off). Then, the compression load of the piston suddenly increases (or decreases), and the engine 2 stops (or the crankshaft rotates extra) as soon as the brake is applied.
As a result, by changing the throttle opening from turning off the ignition switch 21 to stopping the engine 2 for a certain holding time (D), the crank inertia just before the stop of the engine 2 and the mechanical loss (mechanical loss) of the engine 2 are achieved. The engine 2 is prevented from stopping at the crank TOP position (valve overlap position) in which both the intake valve and the exhaust valve are opened, and the restartability of the engine 2 is improved.

As a result, in this first embodiment, the control means 12 adjusts the throttle opening degree of the throttle valve 7 that can adjust the amount of air sucked into the engine 2 according to the command from the engine control means 23. If the engine speed detected by the crank angle sensor 15 as the engine speed detecting means after the fuel supply stop control is executed by the means 25 and the fuel stop control means 24 is less than the set speed, the throttle opening is performed. And an engine rotation stop control means 26 for increasing the throttle opening adjusted by the degree control means 25 beyond the control start opening (A) when the fuel stop control means 24 starts control.
This prevents the engine 2 from stopping while the valve overlap state in which both the intake valve and the exhaust valve of the engine 2 are opened, and thereby unburned gas remaining in the exhaust system flows back to the intake system. Therefore, the startability of the engine 2 at the next start can be improved.

Further, the engine rotation stop control means 26 increases the throttle opening from the control start opening (A) until the holding time (D) set so as to increase as the engine water temperature increases. To maintain.
Thereby, it is possible to realize stop position control of the engine 2 with high accuracy according to the warm-up state of the engine 2.

4 and 5 show a second embodiment of the present invention.
In the second embodiment, portions that perform the same functions as those of the first embodiment will be described with the same reference numerals.
The features of the second embodiment are as follows. That is, as shown in FIG. 4, in the engine control apparatus 1 in the first embodiment, the control means 12 is a throttle valve capable of adjusting the amount of air drawn into the engine 2 in response to a command from the engine control means 23. The throttle opening control means 25 for adjusting the throttle opening amount 7, the elapsed time measurement means 27 for measuring the elapsed time after the fuel supply stop control by the fuel stop control means 24, and the fuel supply by the fuel stop control means 24 When the elapsed time measured by the elapsed time measuring means 27 after the stop control is performed is equal to or longer than the set time (B), the throttle opening adjusted by the throttle opening control means 25 is set to the fuel stop control means 24. And an engine rotation stop control means 26 for increasing the control opening degree (A) at the start of the control.
The set time (B) is a time condition after the ignition switch 21 is turned off, and is set for each engine speed (NE) immediately before the ignition switch 21 is turned off. When the engine speed (NE) is small, the set time (B) is set shorter. On the other hand, when the engine speed (NE) is large, the engine speed is set longer.

Next, the operation of the second embodiment will be described based on the flowchart of FIG.
As shown in FIG. 5, when the program of the control means 12 is started (step B01), it is first determined whether or not the ignition switch 21 is turned off (step B02). If this step B02 is NO, Continue judgment.
If this step B02 is YES, the fuel supply is stopped, the engine speed starts to decrease, and the throttle opening is set to the initial control start opening (A) when the ignition switch 21 is turned off. (Step B03). This control opening degree (A) is one of throttle opening conditions.
Then, after the ignition switch 21 is turned off, it is determined whether or not the set time (B) has elapsed (step B04). If this step B04 is NO, this determination is continued.
If this step B04 is YES, the throttle opening is changed to the set opening (C) so as to increase from the opening (A) at the start of control, and maintained for a predetermined holding time (D). The amount is increased (step B05). The set opening degree (C) is one of throttle opening conditions, and has a relationship of fully closed ≦ C ≦ fully open. The holding time (D) is the throttle opening holding time, and can be set for each engine water temperature. The engine water temperature is set short when the engine water temperature is low, while it is set long when the engine water temperature is high.
Then, the throttle opening is returned to the initial control opening (A) (step B06), the engine 2 is stopped (step B07), and the program is terminated (step B08).

  According to the second embodiment, the same effect as in the first embodiment can be obtained, and the change condition of the throttle opening from the ignition switch 21 off can be changed from the ignition switch 21 off instead of the engine speed. Therefore, even if the crank angle sensor 15 fails, it can be dealt with.

  Changing the throttle opening from the time when the ignition signal is switched from on to off until the engine is stopped can be applied to other controls.

1 is a system configuration diagram of an engine control device in a first embodiment. FIG. It is a flowchart of engine control in 1st Example. It is a time chart of engine control in the 1st example. It is a system block diagram of the control apparatus of an engine in 2nd Example. It is a flowchart of engine control in 2nd Example. It is a time chart of engine control in the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine control apparatus 2 Engine 12 Control means 15 Crank angle sensor 17 Engine water temperature sensor 18 Throttle opening sensor 21 Ignition switch 22 Central processing unit 23 Engine control means 24 Fuel stop control means 25 Throttle opening control means 26 Engine rotation stop control Means 27 Elapsed time measuring means

Claims (3)

  Control means comprising: engine control means for controlling the engine based on various detection signals from each signal detection means; and fuel stop control means for stopping supply of fuel when the ignition signal is switched from on to off. The engine control device provided includes engine speed detection means for detecting the engine speed of the engine, and the control means is capable of adjusting the amount of air taken into the engine in response to a command from the engine control means. The throttle opening degree control means for adjusting the throttle opening amount of the throttle valve, and the engine speed detected by the engine speed detection means after the fuel supply stop control is performed by the fuel stop control means is less than the set speed In this case, the throttle opening adjusted by the throttle opening control means is set to the fuel stop. Control apparatus for an engine, characterized in that it comprises an engine rotation stop control means for increasing than the control start opening at the control start of the control means.   Control means comprising: engine control means for controlling the engine based on various detection signals from each signal detection means; and fuel stop control means for stopping supply of fuel when the ignition signal is switched from on to off. In the engine control apparatus provided, the control means includes a throttle opening control means for adjusting a throttle opening amount of a throttle valve capable of adjusting an air amount taken into the engine by a command from the engine control means, An elapsed time measuring means for measuring an elapsed time after execution of the fuel supply stop control by the fuel stop control means, and an elapsed time measured by the elapsed time measuring means after the fuel supply stop control is executed by the fuel stop control means. If the time exceeds the set time, the throttle opening adjusted by the throttle opening control means Control apparatus for an engine, characterized in that it comprises an engine rotation stop control means for increasing than the control start opening at control start of the fuel stop control means.   The engine rotation stop control means maintains the throttle opening increased from the opening at the start of control until a holding time set so as to become longer as the engine water temperature becomes higher elapses. The engine control device according to claim 1 or 2.

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