JP2010174676A - Stop control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stop control device for an internal combustion engine, capable of appropriately carrying out stop control even when an acceleration pedal is operated immediately before an ignition switch is turned off. <P>SOLUTION: When an engine speed NE is at or below a first speed NE_A after a stop instruction of the engine 3 is issued, the stop control device 1 for the engine 3 overrides a setting of a throttle valve opening ATH in accordance with accelerator aperture AP (step 4 in Fig.4), sets the throttle valve opening ATH to a first predetermined aperture TH_A of a closed side (steps 6, 7 in Fig.4, and Fig.5), and thereafter sets to a second predetermined aperture TH_B of an open side (steps 8, 9 in Fig.4, and Fig.5). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine stop control device that controls an internal combustion engine when the internal combustion engine is stopped.

  As a conventional stop control device for an internal combustion engine, for example, one disclosed in Patent Document 1 is known. The internal combustion engine includes an intake air amount adjustment valve that is disposed in the intake passage and adjusts the intake air amount, and a control device that controls the opening amount of the intake air amount adjustment valve in accordance with the opening amount of the accelerator pedal. Further, in this stop control device, when the internal combustion engine is restarted because the injected fuel remains in the cylinder without burning by continuing the operation of the internal combustion engine for a predetermined period after the ignition switch is turned off. The deterioration of startability and exhaust gas characteristics is prevented. In addition, during the continuous operation of the internal combustion engine, the output of the internal combustion engine does not change even if the accelerator pedal is depressed by invalidating the opening setting of the intake air amount adjustment valve according to the operation of the accelerator pedal. Yes.

JP 2006-161785 A

  However, in this conventional internal combustion engine stop control device, when the ignition switch is turned off, the operation of the internal combustion engine is continued in order to discharge the fuel remaining in the cylinder. Is consumed and fuel consumption deteriorates. Even if such continuous operation is performed, the internal combustion engine may stop in a state where valve overlap occurs in which both the intake valve and the exhaust valve are open. As a result, the exhaust gas in the exhaust pipe flows back into the intake pipe through the cylinder to the intake pipe, so that startability and exhaust gas characteristics may be deteriorated when the internal combustion engine is restarted.

  The present invention has been made to solve the above-described problems, and is a stop of an internal combustion engine that can appropriately perform stop control even when an accelerator pedal is operated immediately before turning off an ignition switch. An object is to provide a control device.

  In order to achieve the above object, the invention according to claim 1 is mounted on a vehicle having an accelerator pedal and is disposed in an intake passage (intake pipe 4 in the embodiment (hereinafter the same in this section)), The internal combustion engine stop control device 1 controls the internal combustion engine 3 having an intake air amount adjustment valve (throttle valve 13a) for adjusting the intake air amount by changing the opening degree (throttle valve opening degree ATH). The accelerator opening detecting means (accelerator opening sensor 22) for detecting the opening of the accelerator pedal (accelerator opening AP), and the opening of the intake air amount adjusting valve according to the detected opening of the accelerator pedal. Driving valve opening degree setting means for setting (ECU 2, TH actuator 13b, step 2 in FIG. 4) and rotation speed detection means for detecting the rotation speed of the internal combustion engine 3 (engine rotation speed NE) Crank angle sensor 24), stop command determining means (ECU 2, step 1 in FIG. 4) for determining whether or not a stop command for internal combustion engine 3 has been issued, and detected after it has been determined that a stop command has been issued. When the rotational speed of the internal combustion engine 3 becomes a predetermined value (first rotational speed NE_A) or less, the opening degree of the intake air amount adjustment valve is set by the operating valve opening degree setting means according to the opening degree of the accelerator pedal. Is disabled, and the opening of the intake air amount adjustment valve is set to the first opening degree TH_A on the closing side, and then the opening amount of the intake air amount adjustment valve is set to the second opening degree TH_B on the opening side. Degree setting means (ECU 2, steps 6 to 9 in FIG. 4).

  In this internal combustion engine stop control device, the opening amount of the intake air amount adjusting valve is set in accordance with the detected opening amount of the accelerator pedal, and the intake air amount is adjusted. In addition, after the stop command for the internal combustion engine is issued, the opening of the intake air amount adjustment valve is set to a predetermined first opening on the closing side, and then set to a predetermined second opening on the opening side. The stop control is executed by. As a result, it is possible to prevent the negative pressure from being generated in the intake passage, so that the backflow of exhaust gas from the exhaust passage to the intake passage during stoppage and the deterioration of the startability and exhaust gas characteristics at the time of restart of the internal combustion engine resulting therefrom Can be avoided.

  Further, if the opening amount of the intake air amount adjusting valve is immediately increased after the stop command is issued, the intake air amount into the cylinder increases, and accordingly, the rotational speed of the internal combustion engine rapidly increases, which is uncomfortable. Vibration and abnormal noise may occur. On the other hand, according to the present invention, since the opening of the intake air amount adjusting valve is once set to the first opening on the closing side after the stop command, it is uncomfortable by reliably reducing the rotational speed of the internal combustion engine. Generation of vibration and abnormal noise can be prevented.

  Furthermore, in the present invention, after the stop command is issued, when the detected number of rotations of the internal combustion engine becomes a predetermined value or less, the opening amount of the intake air amount adjustment valve is set according to the opening amount of the accelerator pedal. While invalidating, the opening degree of the intake air amount adjusting valve is set to the first opening degree. Thus, immediately before the stop command is issued, even when the speed of the internal combustion engine increases due to the operation of the accelerator pedal, the stop control can be started under a constant condition that the speed of the internal combustion engine has decreased to a predetermined value. it can. As a result, the number of revolutions of the internal combustion engine during the stop control and the magnitude of the negative pressure in the intake passage can be appropriately controlled. As a result, the stop control can be performed with high accuracy, and the above-described operation can be effectively obtained. be able to.

  According to a second aspect of the present invention, in the stop control device 1 for an internal combustion engine according to the first aspect, the stop valve opening degree setting means has a second opening degree so as to stop the piston 3b of the internal combustion engine 3 at a predetermined position. This is characterized in that TH_B is set (step 8 in FIG. 4).

  According to this configuration, the piston can be stopped at a predetermined position by setting the second opening. For example, if the piston stops in a valve overlap state where both the intake and exhaust valves are open, it may cause problems such as backflow of exhaust gas through the intake / exhaust valves and deterioration of startability and exhaust gas characteristics. Therefore, the above-described problems can be avoided by setting the predetermined position of the piston to a position where no valve overlap occurs.

It is a figure showing roughly an internal-combustion engine to which a stop control device by this embodiment is applied. It is a block diagram of a stop control device. It is sectional drawing which shows schematic structure of the intake side valve mechanism and the exhaust side valve mechanism of an internal combustion engine. It is a flowchart which shows a throttle valve opening degree control process. It is a figure which shows an example of a throttle valve opening degree map. It is a timing chart which shows the operation example obtained by throttle valve opening degree control processing.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an internal combustion engine 3 to which a stop control device 1 (see FIG. 2) according to the present embodiment is applied. The internal combustion engine (hereinafter referred to as “engine”) 3 is, for example, an in-line 4-cylinder type gasoline engine mounted on a vehicle (not shown).

  A fuel injection valve 6 (see FIG. 2) is attached to each cylinder 3a of the engine 3. The fuel injection amount injected from the fuel injection valve 6 is controlled by controlling the valve opening time by the ECU 2 (see FIG. 2).

  An intake pipe 4 and an exhaust pipe 5 are connected to a cylinder head 3b of the engine 3 for each cylinder 3a, and a pair of intake valves 8, 8 (only one is shown) and a pair of exhaust valves 9, 9 (1 Only one is shown).

  The intake valve 8 is opened and closed by an intake side valve mechanism 40. The intake side valve mechanism 40 is of a cam drive type, and as shown in FIG. 3, a rotatable intake camshaft 41, an intake cam 42 provided integrally with the intake camshaft 41, and an intake rocker arm A shaft 43 and two intake rocker arms 44 and 44 (only one is shown) that are rotatably supported by the intake rocker arm shaft 43 and abut against the upper ends of the intake valves 8 and 8 are provided.

  The intake camshaft 41 is connected to the crankshaft 3c via an intake sprocket and a timing chain (both not shown), and rotates once every two rotations of the crankshaft 3c. When the intake camshaft 41 rotates, the rocker arms 44, 44 are pressed by the intake cam 42, and rotate about the rocker arm shaft 43, whereby the intake valves 8, 8 are opened and closed.

  The exhaust side valve mechanism 60 that drives the exhaust valve 9 is also of the same cam drive type as the intake side mechanism, and includes a rotatable exhaust camshaft 61, an exhaust cam 62 integral with the exhaust camshaft 61, The exhaust rocker arm shaft 63 and two exhaust rocker arms 64 and 64 (only one shown) that are rotatably supported by the exhaust rocker arm shaft 63 and abut against the upper ends of the exhaust valves 9 and 9 are provided. .

  The exhaust camshaft 61 is connected to the crankshaft 3c via an exhaust sprocket and a timing chain (both not shown), and rotates once every two rotations of the crankshaft 3c. When the exhaust camshaft 61 rotates, the rocker arms 64, 64 are pressed by the exhaust cam 62, and rotate about the exhaust rocker arm shaft 63, thereby opening and closing the exhaust valves 9, 9.

  The engine 3 is connected to an ignition switch (SW) 21 (see FIG. 2). The ignition switch 21 is a switch that is provided in a driver's seat (not shown) of the vehicle and that starts and stops the engine 3. A predetermined signal is output to the ECU 2 in accordance with the on / off of the ignition switch 21.

  The engine 3 is provided with a crank angle sensor 24. The crank angle sensor 24 includes a magnet rotor and an MRE pickup (both not shown), and outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3c rotates.

  The CRK signal is output at every predetermined crank angle. The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3d of the cylinder 3a is at a predetermined crank angle position near the TDC (top dead center) at the start of the intake stroke. In the case of the four-cylinder type as in the present embodiment, Is output every 180 ° of crank angle.

  The intake pipe 4 is provided with a throttle valve mechanism 13. The throttle valve mechanism 13 has a throttle valve 13a rotatably provided in the intake pipe 4 and a TH actuator 13b that drives the throttle valve 13a. The TH actuator 13b is a combination of a motor and a gear mechanism (both not shown), and is driven by a drive signal from the ECU 2. Thus, the amount of fresh air (hereinafter referred to as “intake amount”) sucked into the cylinder 3a is controlled by changing the opening ATH of the throttle valve 13a (hereinafter referred to as “throttle valve opening”) ATH. The throttle valve opening ATH is detected by a throttle valve opening sensor 23 (see FIG. 2), and the detection signal is output to the ECU 2.

  The ECU 2 is connected to a water temperature sensor 22 and an accelerator opening sensor 25 (both refer to FIG. 2). The water temperature sensor 22 detects the coolant temperature (hereinafter referred to as “engine water temperature”) TW of the engine 3, and the accelerator opening sensor 25 is operated by an accelerator pedal (not shown) (hereinafter referred to as “accelerator opening”). APs are detected, and those detection signals are output to the ECU 2.

  The ECU 2 is composed of a microcomputer including an I / O interface, a CPU, a RAM, and a ROM (all not shown). The detection signals from the various sensors 22 to 25 described above are input to the CPU after A / D conversion and shaping by the I / O interface. In accordance with these input signals, the ECU 2 determines the operating state of the engine 3 according to a control program stored in the ROM, and executes engine control including stop control of the engine 3 according to the determined operating state.

  In the present embodiment, the ECU 2 corresponds to an operating valve opening degree setting means, a stop command determining means, and a stopping valve opening degree setting means. Hereinafter, the process performed by ECU2 is demonstrated, referring drawings.

  FIG. 4 shows a throttle valve opening degree control process executed by the ECU 2. This process is executed every predetermined time (for example, 10 msec). First, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the ignition switch 21 is OFF. When this answer is NO, it is determined that the stop command has not been issued and the engine 3 is in operation, the throttle valve opening ATH is set according to the accelerator opening AP (step 2), and this process is terminated. . In this case, the throttle valve opening ATH is set to a larger value as the accelerator opening AP is larger. Further, at the time of idling operation where the accelerator pedal opening AP is zero, the throttle valve opening ATH is set to the idling opening TH_IDL. The idling opening TH_IDL is set by feedback control so that the engine speed NE becomes the target idle speed NE_IDL set according to the engine coolant temperature TW.

  On the other hand, if the answer to step 1 is YES and the ignition switch 21 is turned off, it is determined that the engine is stopped, and it is determined whether or not the engine speed NE is equal to or lower than a predetermined first speed NE_A (step 3). If the answer to this question is NO and the engine speed has not decreased to the first rotational speed NE_A, the setting of the throttle valve opening ATH corresponding to the accelerator opening AP is continued by executing the step 2, and the present process is terminated. . In addition, after the ignition switch 21 is turned off to promote combustion of fuel adhering to the intake pipe 4 and the cylinder 3a, ignition by a spark plug (not shown) is continued until the engine 3 is completely stopped. May be. In this case, the first rotational speed NE_A is preferably set to a rotational speed lower than the target idle rotational speed NE_IDL (for example, 650 rpm) from the viewpoint of promoting the combustion of the attached fuel, and from the viewpoint of avoiding vibration of the engine 3. Therefore, it is preferable to set the rotational speed higher than the rotational speed at which the engine 3 resonates (generally between 500 to 600 rpm). For example, in the present embodiment, 600 rpm is set as the first rotation speed NE_A. However, the present invention is not limited to this, and the target idle speed NE_IDL may be set as the first speed NE_A.

  On the other hand, if the answer to step 3 is YES and the engine speed NE is equal to or lower than the first speed NE_A, the setting of the throttle valve opening ATH corresponding to the accelerator opening AP is invalidated (step 4). Next, it is determined whether or not the engine rotational speed NE is equal to or lower than a predetermined second rotational speed NE_B (for example, 500 rpm) smaller than the first rotational speed NE_A (step 5). When this answer is NO, the first opening TH_A is calculated by searching the throttle valve opening map shown in FIG. 5 according to the engine water temperature TW (step 6) and set as the throttle valve opening ATH. (Step 7).

  The first opening TH_A is set in order to reliably reduce the engine speed NE by reducing the intake air amount. For this reason, in the throttle valve opening map, as described above. It is set to a value smaller than the set idling opening TH_IDL. That is, when the engine speed NE becomes equal to or lower than the first speed NE_A, the throttle valve opening ATH is controlled to the close side. Further, the first opening TH_A is set to a larger value as the engine coolant temperature TW is higher. This is to compensate for the fact that the higher the engine coolant temperature TW, the higher the temperature of the intake air taken into the cylinder 3a, the lower the density and the lower the actual intake air amount. .

  On the other hand, when the answer to step 5 is YES and the engine speed NE is equal to or lower than the second speed NE_B, the second opening TH_B is searched by searching the throttle valve opening map according to the engine water temperature TW. Is calculated (step 8) and set as the throttle valve opening ATH (step 9), and this process is terminated.

  The second opening TH_B is set in order not to generate a negative pressure in the intake pipe 4. For this reason, the second opening TH_B is set to a value larger than the first opening TH_A for the same engine coolant temperature TW. That is, when the engine speed NE becomes equal to or lower than the second speed NE_B, the throttle valve opening ATH is controlled to the open side. Further, the second opening degree TH_B is set to a larger value as the engine coolant temperature TW is higher for the same reason as in the case of the first opening degree TH_A.

  The second opening TH_B is set so that the piston 3d stops at a predetermined position where the valve overlap is not generated in which both the intake valve 8 and the exhaust valve 9 are opened. The stop position of the piston 3d changes according to the engine speed NE and the negative pressure PB in the intake pipe 4, and the relationship can be obtained by experiments. The second opening TH_B in the throttle valve opening map represents the result of an experiment performed in advance. By setting the second opening TH_B in this way, valve overlap when the engine 3 is stopped is prevented, and when the exhaust pipe 5 is stopped, the backflow of exhaust gas to the intake pipe 4 via the cylinder 3a or the engine The deterioration of startability and exhaust gas characteristics at the time of restart 3 is avoided.

  FIG. 6 shows an example of the operation obtained by the throttle valve opening control process described so far when the accelerator pedal is operated immediately before the ignition switch 21 is turned off. When the accelerator pedal is operated and the accelerator pedal opening AP is increased at a time point t0 immediately before the stop, the throttle valve opening ATH is set according to the accelerator pedal opening AP (step 2), thereby increasing the engine speed NE. To do. Immediately after that, when the ignition switch (IGSW) 21 is turned off (t1, step 1: YES), the supply of fuel from the fuel injection valve 6 is stopped, whereby the engine speed NE decreases. Thereafter, until the engine speed NE becomes equal to or less than the first speed NE_A, the throttle valve opening ATH is set to an opening corresponding to the accelerator opening AP by continuously executing step 2. (Between t1 and t2).

  When the engine speed NE reaches the first speed NE_A (t2, step 3: YES), the setting of the throttle valve opening ATH corresponding to the accelerator opening AP is invalidated (step 4). The throttle valve opening ATH is set to the first opening TH_A on the closing side (step 7). Along with this, the intake pressure PBA in the intake pipe 4 decreases, and the negative pressure PB, which is the difference between the intake pressure PBA and the atmospheric pressure PA (PBA−PA), increases. Thereafter, when the engine speed NE becomes the second speed NE_B (t3, step 5: YES), the throttle valve opening TH is set to the opening-side second opening TH_B (step 9). Along with this, the intake pressure PBA increases and the negative pressure PB decreases. Then, the engine speed NE becomes zero, the engine 3 stops in a state where no valve overlap occurs, the intake pressure PBA becomes equal to the atmospheric pressure PA, and the negative pressure PB becomes zero (t4).

  As described above, according to the present embodiment, during the operation of the engine 3, the throttle valve opening ATH is set according to the accelerator opening AP, and the intake air amount is adjusted. Further, after the ignition switch 21 is turned off, the throttle valve opening ATH is set to a predetermined first opening TH_A on the closing side, and then set to a predetermined second opening TH_B on the opening side. As a result, it is possible to prevent the negative pressure PB from being generated in the intake pipe 4, and therefore, it is possible to prevent the backflow of exhaust gas from the exhaust pipe 5 to the intake pipe 4 through the cylinder 3 a while stopping, and the engine 3 resulting therefrom Deterioration of startability and exhaust gas characteristics during restart can be avoided.

  Further, by setting the first opening TH_A on the closing side before the throttle valve opening ATH is set to the second opening TH_B, the engine speed NE is reliably reduced. Generation of unpleasant vibrations and abnormal noise due to excessive increase can be prevented.

  Further, when the engine speed NE becomes the first speed NE_A after the ignition switch 21 is turned off, the setting of the throttle valve opening ATH corresponding to the accelerator opening AP is invalidated and the throttle valve is opened. The degree ATH is set to the first opening TH_A. Thus, immediately before the ignition switch 21 is turned off, even when the engine speed NE increases due to the operation of the accelerator pedal, the stop control is started under a constant condition that the engine speed NE has decreased to the first speed NE_A. be able to. As a result, the engine speed NE during the stop control and the magnitude of the negative pressure PB generated in the intake pipe 4 can be appropriately controlled. As a result, the stop control can be performed with high accuracy, and the effects described above can be obtained. It can be obtained effectively.

  Further, since the throttle valve opening ATH is set to the second opening TH_B when the engine speed NE decreases to the second rotation speed NE_B, certain conditions under which the engine rotation speed NE decreases to the second rotation speed NE_B. Thus, it is possible to start control for stopping the piston 3d at a predetermined position where no valve overlap occurs. As a result, the engine speed NE and the magnitude of the negative pressure PB generated in the intake pipe 4 can be appropriately controlled before the piston 3d stops, and as a result, the piston 3d does not generate a valve overlap. The position can be accurately stopped.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, it is determined whether or not a stop command for the engine 3 has been issued based on whether the ignition switch 21 is on or off. However, the present invention is not limited to this. For example, idling is automatically performed while the vehicle is stopped. In the case of having an idle stop function for stopping idling, it may be performed based on a signal for stopping idling.

  In the embodiment, the first opening TH_A is set according to the engine coolant temperature TW, but the intake air amount may be detected and set according to the detected intake air amount. Further, step 6 in FIG. 4 may be omitted, and the first opening TH_A may be set to a predetermined value (for example, a value corresponding to a fully closed opening) regardless of the engine coolant temperature TW or the like.

  Further, the first opening TH_A is set to be constant regardless of the engine speed NE, but may be set to gradually increase as the engine speed NE decreases, for example. Further, step 6 in FIG. 4 may be omitted, and the first opening TH_A may be calculated using a parameter (for example, crank angle position) other than the engine coolant temperature TW.

  The embodiment is an example in which the present invention is applied to a gasoline engine mounted on a vehicle, but the present invention is not limited to this, and may be applied to various engines such as a diesel engine other than a gasoline engine. Also, the present invention can be applied to engines other than those for vehicles, for example, engines for marine propulsion devices such as outboard motors having a crankshaft arranged vertically. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 Stop control device 2 ECU (valve opening setting means during operation, stop command determination means, accelerator response invalidation means,
Stop valve opening setting means)
3 Engine (Internal combustion engine)
3d piston 4 intake pipe (intake passage)
13a Throttle valve (intake air amount adjustment valve)
13b TH actuator (valve opening setting means during operation, valve opening setting means during stop)
24 Crank angle sensor (rotation speed detection means)
25 Accelerator opening sensor (valve opening setting means during operation)
ATH Throttle valve opening (opening of intake air adjustment valve)
TH_A 1st opening TH_B 2nd opening AP Accelerator opening NE Engine speed (speed)
NE_A 1st rotation speed (predetermined value)

Claims (2)

Stop control of an internal combustion engine that is mounted on a vehicle having an accelerator pedal and that is disposed in an intake passage and has an intake air amount adjustment valve for adjusting an intake air amount by changing an opening degree, at the time of stopping the internal combustion engine A device,
An accelerator opening detecting means for detecting the opening of the accelerator pedal;
An operating valve opening setting means for setting the opening of the intake air amount adjusting valve in accordance with the detected opening of the accelerator pedal;
A rotational speed detection means for detecting the rotational speed of the internal combustion engine;
Stop command determination means for determining whether or not a stop command for the internal combustion engine has been issued;
After it is determined that the stop command has been issued, when the detected rotational speed of the internal combustion engine becomes a predetermined value or less, the operating valve opening setting means according to the opening of the accelerator pedal The setting of the opening amount of the intake air amount adjusting valve is invalidated, the opening amount of the intake air amount adjusting valve is set to the first opening amount on the closing side, and thereafter, the opening amount of the intake air amount adjusting valve is changed to the first opening amount on the opening side. Stop valve opening setting means for setting to 2 opening;
A stop control device for an internal combustion engine, comprising:   The stop control device for an internal combustion engine according to claim 1, wherein the stop-time valve opening setting means sets the second opening so as to stop the piston of the internal combustion engine at a predetermined position.

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