JP2009127573A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly detect engine stop in engine automatic stop while satisfying demands for lowering cost in a system provided with an engine automatic stop and start device. <P>SOLUTION: This control device calculates a stop judgment time (time to stop of rotation of the engine 11 from passage of a predetermined rotation speed of engine rotation speed) based on a crank angle in passage of the predetermined rotation speed in a process of decrease of engine rotation speed during engine automatic stop. Stop of rotation of the engine 11 is judged at roughly same timing as timing at which rotation of the engine 11 actually stops by judging stop of rotation of the engine 11 when stop judgment time elapses after passage of the predetermined rotation speed of the engine rotation speed. Consequently, stop of the engine 11 can be quickly detected, it is not necessary to newly provided a special sensor or the like capable of detecting reverse rotation of the engine 11, and demand for lowering cost can be satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied, and automatically starts the internal combustion engine when a predetermined automatic start condition is satisfied.

  In recent years, some internal combustion engines mounted on vehicles employ an automatic stop / start device (so-called idling stop device) for the purpose of reducing fuel consumption and exhaust emissions. This automatic stop / start device automatically stops the internal combustion engine when the driver stops the vehicle and a predetermined automatic stop condition is satisfied, and then the driver performs an operation to start the vehicle. Thus, the internal combustion engine is automatically restarted when a predetermined automatic start condition is satisfied.

Further, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2001-263147), in a hybrid vehicle having a configuration in which a motor generator is connected to a crankshaft of an internal combustion engine, the internal combustion engine is automatically stopped when the internal combustion engine is automatically stopped. When the reverse rotation of the internal combustion engine (reverse rotation of the crankshaft) is detected based on the output signal of the resolver of the motor generator that rotates in conjunction with the rotation of the motor, or the output signal (pulse signal) from the crank angle sensor is input In some cases, it is determined that the internal combustion engine has stopped when a predetermined time (for example, 1.5 sec) elapses.
JP 2001-263147 A (the second page etc.)

  In general, since the crank angle sensor provided in the internal combustion engine cannot detect the reverse rotation of the internal combustion engine, in the hybrid vehicle described in Patent Document 1, the resolver of the motor generator that rotates in conjunction with the rotation of the internal combustion engine, Although it is used as a reverse rotation detection means for detecting the reverse rotation of the internal combustion engine, in a vehicle not equipped with a sensor such as a resolver that can be used as such a reverse rotation detection means, a special engine capable of detecting the reverse rotation of the internal combustion engine. There is a problem that it is necessary to newly provide a new sensor and the like, and it is impossible to satisfy the demand for cost reduction.

  Further, as in Patent Document 1, a stop determination system that determines that an internal combustion engine has stopped when a predetermined time (for example, 1.5 sec) has passed without an output signal from a crank angle sensor being input, Even if the engine is actually stopped, if the engine does not wait until the state where the output signal from the crank angle sensor is not input continues for a predetermined time, the internal combustion engine is not detected to be stopped. There is a problem that the detection timing is delayed.

  In addition, in a system in which the automatic start is started after detecting the stop of the internal combustion engine, if the delay of the stop detection timing is large with respect to the actual stop timing of the internal combustion engine, the rotation of the internal combustion engine stops during the automatic stop. When an automatic start request is generated by the driver's start operation, etc., the delay between the start of the automatic start request and the start of the automatic start becomes large, and the driver feels uncomfortable ).

  The present invention has been made in view of such circumstances. Accordingly, the object of the present invention is to detect the stop of the internal combustion engine quickly when the internal combustion engine is automatically stopped, and to reduce the cost. An object of the present invention is to provide a control device for an internal combustion engine that can be satisfied.

  In order to achieve the above object, an invention according to claim 1 is directed to an internal combustion engine that automatically stops an internal combustion engine when a predetermined automatic stop condition is satisfied, and automatically starts the internal combustion engine when a predetermined automatic start condition is satisfied. In the engine control device, this corresponds to the time required for the rotation of the internal combustion engine to stop based on the crank angle when passing through the predetermined rotation speed in the process of decreasing the rotation speed of the internal combustion engine when the internal combustion engine is automatically stopped. The stop determination time to be calculated is calculated by the stop determination time calculating means, and the rotation of the internal combustion engine is stopped when the stop determination time elapses after the rotation speed of the internal combustion engine passes a predetermined rotation speed when the internal combustion engine is automatically stopped. This is determined by the stop determination means.

  According to the experiment results of the present inventor, when the internal combustion engine is stopped, the crank angle when passing through the predetermined rotational speed while the rotational speed of the internal combustion engine decreases, and the rotational speed of the internal combustion engine pass through the predetermined rotational speed. It has been found that there is a correlation with the time required for the rotation of the internal combustion engine to stop.

  From this correlation, if the crank angle at which the rotational speed of the internal combustion engine passes a predetermined rotational speed when the internal combustion engine is automatically stopped is used, the rotational speed of the internal combustion engine passes after the predetermined rotational speed passes. The stop determination time corresponding to the time required for the rotation to stop can be accurately calculated. By using the stop determination time obtained in this manner, it is determined that the rotation of the internal combustion engine has stopped when the stop determination time has elapsed after the rotation speed of the internal combustion engine has passed the predetermined rotation speed. It can be determined that the rotation of the internal combustion engine has stopped at almost the same timing as the timing at which the rotation of the engine actually stops, and the stop of the internal combustion engine can be detected quickly. In addition, since it is not necessary to newly provide a special sensor or the like that can detect the reverse rotation of the internal combustion engine, it is possible to satisfy the demand for cost reduction.

  By the way, the pumping loss and the in-cylinder pressure change depending on the throttle opening when the internal combustion engine stops, and the time required for the internal combustion engine to stop rotating after the rotational speed of the internal combustion engine passes the predetermined rotational speed changes. To do.

  Therefore, as in claim 2, the stop determination time may be corrected according to the throttle opening. In this way, the time required for the rotation of the internal combustion engine to stop after the rotation speed of the internal combustion engine passes the predetermined rotation speed changes according to the throttle opening when the internal combustion engine stops. Correspondingly, the stop determination time can be corrected appropriately. As a result, the stop determination time can be set with high accuracy regardless of the throttle opening when the internal combustion engine stops, and the stop determination accuracy of the internal combustion engine can be further improved.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.

  An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 for introducing air into each cylinder of the engine 11, and a fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. Yes. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 29 that detects knocking vibration are attached to the cylinder block of the engine 11. A crank angle sensor 28 that outputs a pulse signal every time the crankshaft 27 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 27. Based on the output signal of the crank angle sensor 28, the crank angle and engine The rotation speed is detected.

  Outputs of these various sensors are input to a control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) so that the fuel injection amount of the fuel injection valve 21 can be determined according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  The ECU 30 executes routines for engine automatic stop / start control shown in FIGS. 2 and 3 to be described later, so that fuel injection and ignition are performed when the automatic stop condition is satisfied during engine operation and stopping. Is stopped and the engine 11 is automatically stopped. When the engine is stopped and the driver performs an operation to start the vehicle and the automatic start condition is satisfied, the engine 11 is automatically The start control is restarted.

  At this time, the ECU 30 determines the stop determination time DLY (the engine speed NE is determined based on the crank angle CRNK0 when the engine speed NE passes through a predetermined speed K (for example, 200 rpm) while the engine speed NE is decreasing. The time required for the rotation of the engine 11 to stop after passing through the predetermined rotation speed K is calculated, and the engine 11 when the stop determination time DLY has elapsed after the engine rotation speed NE has passed through the predetermined rotation speed K is calculated. Is determined to have stopped rotating.

  According to the results of experiments by the present inventor, when the engine 11 is stopped, the crank angle CRNK0 when the engine speed NE passes the predetermined speed K while the engine speed NE decreases and the engine speed NE passes the predetermined speed K. It has been found that there is a correlation with the time required for the rotation of the engine 11 to stop.

  Therefore, if the crank angle CRNK0 when the engine speed NE passes the predetermined rotational speed K when the engine 11 is automatically stopped is used, the engine 11 rotates after the engine rotational speed NE passes the predetermined rotational speed K. The stop determination time DLY corresponding to the time required for stopping can be calculated with high accuracy. By using the stop determination time DLY obtained in this way, it is determined that the rotation of the engine 11 has stopped when the stop determination time DLY has elapsed after the engine rotation speed NE has passed the predetermined rotation speed K. It can be determined that the rotation of the engine 11 has stopped at substantially the same timing as when the rotation of the engine 11 actually stops.

The processing contents of the routines for engine automatic stop / start control in FIGS. 2 and 3 executed by the ECU 30 will be described below.
[Engine automatic stop / start control routine]
The engine automatic stop / start control routine shown in FIG. 2 is executed at a predetermined cycle while the ECU 30 is powered on. When this routine is started, first, at step 101, it is determined whether or not the engine is operating, and at the next step 102, it is determined whether or not an automatic stop request has been generated. Here, the automatic stop request is generated, for example, when the brake pedal is depressed and the vehicle is stopped for a predetermined time.

  If it is determined in step 101 that the engine is not operating, or if it is determined in step 102 that an automatic stop request has not been generated, the process of steps 103 and 104 is skipped and the process proceeds to step 105. .

  On the other hand, if it is determined in step 101 that the engine is operating and it is determined in step 102 that an automatic stop request has been generated, it is determined that the automatic stop condition is satisfied, and the process proceeds to step 103. Then, stop control for stopping the fuel injection and ignition to automatically stop the engine 11 is executed.

  Thereafter, the routine proceeds to step 104, where an engine stop determination routine of FIG. 3 described later is executed, and when it is determined that the rotation of the engine 11 has stopped, the engine stop determination flag ENST is set to “1”.

  Thereafter, the process proceeds to step 105, where it is determined whether or not an automatic start request has occurred. Here, the automatic start request is generated, for example, when the accelerator pedal is depressed, when the brake pedal is released, or when the shift lever is shifted from the P range to the D range. Thereafter, the routine proceeds to step 106, where it is determined whether or not the engine is stopped depending on whether or not the engine stop determination flag ENST is set to “1”.

  If it is determined in step 105 that an automatic start request has not occurred, or if it is determined in step 106 that the engine is not stopped (ENST = 0), the process of step 107 is not performed. This routine is terminated.

  On the other hand, if it is determined in step 105 that an automatic start request has occurred, and if it is determined in step 106 that the engine is stopped (ENST = 1), it is determined that the automatic start condition is satisfied. Then, the routine proceeds to step 107, where start control for automatically restarting the engine 11 is executed.

[Engine stop determination routine]
The engine stop determination routine shown in FIG. 3 is a subroutine executed in step 104 of the engine automatic stop / start control routine of FIG. When this routine is started, first, in step 201, various operating parameters (engine rotational speed NE, crank angle CRNK, throttle opening degree TA, etc.) are read.

  Thereafter, the routine proceeds to step 202, where the predetermined rotational speed K is set in the process of decreasing the engine rotational speed NE when the engine is automatically stopped depending on whether the engine rotational speed NE is lower than a predetermined rotational speed K (for example, 200 rpm). It is determined whether or not it has passed.

  If it is determined in step 202 that the engine rotational speed NE is equal to or higher than the predetermined rotational speed K, it is determined that the engine rotational speed NE has not yet passed the predetermined rotational speed K, and the process proceeds to step 203. The map search completion flag F is reset or maintained to “0”, and the count value of the counter CNT for counting the elapsed time after the engine speed NE has passed the predetermined speed K is reset or maintained to “0”. To do. The counter CNT is a counter that is automatically incremented every predetermined time.

  Thereafter, if it is determined in step 202 that the engine rotational speed NE is lower than the predetermined rotational speed K, it is determined that the engine rotational speed NE has passed the predetermined rotational speed K, the process proceeds to step 204, and the map It is determined whether or not the search completion flag F is “0”.

  Since the map search completion flag F is “0” for the first time immediately after the engine speed NE has passed the predetermined rotation speed K, it is determined in this step 204 that the map search completion flag F is “0”. In step 205, the current crank angle CRNK is set to the crank angle CRNK0 when the predetermined rotational speed is passed (the crank angle when the engine rotational speed NE has passed the predetermined rotational speed K).

  Thereafter, the routine proceeds to step 206, and referring to the map of the stop determination time DLY shown in FIG. 4, the stop determination time DLY (the engine rotation speed NE is equal to the predetermined rotation speed K) corresponding to the crank angle CRNK0 when the predetermined rotation speed is passed. The time required for the rotation of the engine 11 to stop after passing through is calculated. The processing in step 206 serves as a stop determination time calculating means in the claims.

  The map of the stop determination time DLY shown in FIG. 4 is set in advance based on experimental data, design data, and the like, and is stored in the ROM of the ECU 30. FIG. 4 shows an example of a map of the stop determination time DLY in the case of a four-cylinder engine. In the case of a four-cylinder engine, the stop determination time DLY is reached at a cycle of 180 ° C. with a compression stroke every 180 ° C. Therefore, only the stop determination time DLY in the range of 0 to 180 ° C. is shown.

  By the way, the time required for the rotation of the engine 11 to stop after the pumping loss or the in-cylinder pressure changes depending on the throttle opening TA when the engine 11 stops and the engine rotation speed NE passes the predetermined rotation speed K. Change.

  Therefore, the map of the stop determination time DLY shown in FIG. 4 is set for each area of the throttle opening TA. For example, when the throttle opening TA is smaller than the predetermined opening A, a solid line α in FIG. The map shown in FIG. 4 is selected to calculate the stop determination time DLY, and when the throttle opening degree TA is equal to or greater than the predetermined opening A, the map indicated by the dotted line β in FIG. 4 is selected to calculate the stop determination time DLY. Thus, the stop determination time DLY is corrected according to the throttle opening degree TA. As a result, the time required for the rotation of the engine 11 to stop after the engine rotation speed NE has passed the predetermined rotation speed K changes in accordance with the throttle opening TA when the engine 11 stops. Thus, the stop determination time DLY is corrected appropriately. Furthermore, the stop determination time DLY may be corrected according to temperature information such as the cooling water temperature and the oil temperature.

  After setting the stop determination time DLY in this way, the process proceeds to step 207 to reset or maintain the count value of the counter CNT to “0” and set the map search completion flag F to “1”.

  After the map search completion flag F is set to “1” in step 207, it is determined in step 204 that the map search completion flag F is not “0”, and the processing of steps 205 to 207 is skipped. The process proceeds to step 208.

  In step 208, the engine rotation speed NE is determined according to whether the count value of the counter CNT (the elapsed time after the engine rotation speed NE has passed the predetermined rotation speed K) is equal to or greater than the stop determination time DLY. It is determined whether or not the stop determination time DLY has elapsed since passing.

  If it is determined in step 208 that the count value of the counter CNT has not reached the stop determination time DLY, the stop determination time DLY has not elapsed since the engine rotation speed NE has passed the predetermined rotation speed K. In step 209, it is determined that the rotation of the engine 11 has not stopped yet, and the engine stop determination flag ENST is maintained at “0”.

  Thereafter, when it is determined in step 208 that the count value of the counter CNT is equal to or greater than the stop determination time DLY, it is determined that the stop determination time DLY has elapsed after the engine speed NE has passed the predetermined rotation speed K. Then, the process proceeds to step 210, where it is determined that the rotation of the engine 11 has stopped, and the engine stop determination flag ENST is set to “1”.

  The processing of these steps 208 to 210 serves as stop determination means in the claims.

  In the present embodiment described above, the time required for the rotation of the engine 11 to stop based on the crank angle CRNK0 when passing through the predetermined rotation speed K in the course of the decrease in the engine rotation speed NE when the engine is automatically stopped. Since the corresponding stop determination time DLY is calculated and it is determined that the rotation of the engine 11 has stopped when the stop determination time DLY has elapsed after the engine rotation speed NE has passed the predetermined rotation speed K, the engine 11 It can be determined that the rotation of the engine 11 has stopped at substantially the same timing as when the rotation of the engine 11 actually stops, and the stop of the engine 11 can be detected quickly. In addition, since it is not necessary to newly provide a special sensor or the like that can detect the reverse rotation of the engine 11, the demand for cost reduction can be satisfied.

  Further, in a system in which the automatic start of the engine 11 is started after the stop of the engine 11 is detected, if the delay of the stop detection timing is large with respect to the actual stop timing of the engine 11, the rotation of the engine 11 during the automatic stop is performed. If an automatic start request occurs before the vehicle stops, the delay from when the automatic start request occurs until the automatic start starts increases, causing the driver to feel a sense of incongruity (feeling of an automatic start) However, in this embodiment, the delay of the stop detection timing with respect to the actual stop timing of the engine 11 can be reduced (or almost zero), so that the automatic start is started after the automatic start request is generated. The delay until the vehicle can be reduced, and the driver does not feel a sense of incongruity (a feeling of self-starting feeling).

  Furthermore, in this embodiment, the stop determination time DLY is corrected according to the throttle opening TA, so that the engine rotational speed NE is set to the predetermined rotational speed K according to the throttle opening TA when the engine 11 is stopped. The stop determination time DLY can be appropriately corrected in response to a change in the time required for the rotation of the engine 11 to stop after passing through. As a result, the stop determination time DLY can be set with high accuracy regardless of the throttle opening when the engine 11 is stopped, and the stop determination accuracy of the engine 11 can be further improved.

  However, when the throttle opening when the engine 11 is stopped becomes almost the same opening every time, or when the influence of the throttle opening TA is small, a predetermined map with reference to the stop determination time DLY shown in FIG. The correction of the stop determination time DLY corresponding to the throttle opening TA may be omitted by calculating the stop determination time DLY corresponding to the crank angle CRNK0 when the rotational speed passes.

  In the above embodiment, the present invention is applied to a vehicle using only the engine 11 as a power source. However, the present invention may be applied to a hybrid vehicle using an engine and a motor as power sources. The present invention can be widely applied to vehicles equipped with an engine automatic stop / start device that automatically stops the engine when the condition is satisfied and automatically starts the engine when the automatic start condition is satisfied.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a flowchart which shows the flow of a process of an engine automatic stop / start control routine. It is a flowchart which shows the flow of a process of an engine stop determination routine. It is a figure which shows notionally an example of the map (4-cylinder engine) of the stop determination time in the case with correction | amendment according to throttle opening. It is a figure which shows notionally an example of the map (4-cylinder engine) of the stop determination time when there is no correction | amendment according to a throttle opening.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 17 ... Throttle opening sensor, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 28 ... Crank angle sensor, 30 ... ECU (Stop determination time calculation means, stop determination means)

Claims (2)

In a control device for an internal combustion engine that automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied, and automatically starts the internal combustion engine when a predetermined automatic start condition is satisfied,
Calculates the stop determination time corresponding to the time required to stop the rotation of the internal combustion engine based on the crank angle when passing through the predetermined rotation speed while the rotation speed of the internal combustion engine decreases during the automatic stop of the internal combustion engine Stop determination time calculating means for
Stop determining means for determining that the rotation of the internal combustion engine has stopped when the stop determination time has elapsed after the rotational speed of the internal combustion engine has passed the predetermined rotational speed when the internal combustion engine is automatically stopped. A control device for an internal combustion engine.   The control apparatus for an internal combustion engine according to claim 1, wherein the stop determination time calculating means corrects the stop determination time according to a throttle opening.

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