Internal combustion engine stop control device

Invention Patent Descriptive Report for SYSTEM AND INTERRUPTION CONTROL METHOD FOR AN INTERNAL COMBUSTION ENGINE.

Technical Field

The present invention relates to an interrupt control system for controlling a piston interrupted position in an internal combustion engine the moment the engine stops.

Background Technique

Patent document 1 (illustrated below) describes an interruption control system that performs a control to increase the amount of incoming air just before the engine stops to increase the negative rotational torque generated by the cylinder in the compression step. According to this control system, the crank angle range at which the engine stops can be controlled in the narrowest range in comparison to the conventional control method.

Prior Art Document

Patent Document

Patent Document 1: Japanese Patent Published No. 2004,232539

Summary of the Invention

Problems to be solved by the invention

If there is a cylinder that is in the state in which both the inlet valves and the exhaust valve are opened when the engine stops (the state will hereinafter be referred to as the overlap state), the exhaust gas can flow back into the pipe at the time of the next engine start, which makes it difficult to start the engine smoothly. Therefore, it is necessary to carry out the interruption control so that the motor does not stop in the overlapping state.

Although the method described in patent document 1 allows 30 to narrow the crank angle at engine interruption, it is not possible to avoid avoiding engine interruption in the overlapping state with certainty.

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The present invention was created considering the point described above, and an objective of the invention is to provide an interruption control system for an internal combustion engine that allows to avoid with certainty the interruption of the engine in the overlapping state where both the inlet valve and the cylinder exhaust valve are opened.

Means to Solve Problems

In order to achieve the objective described above, the present invention provides an interruption control system for an internal combustion engine having interruption means to interrupt at least one of an ignition and an injection of fuel from the engine based on an interrupt command. of the internal combustion engine, an inlet air flow rate control valve (3) to control an inlet air flow rate of the engine, stop position control means for controlling a stop position of a motor piston by actuation of the inlet air flow rate control valve (3), rotation angle detection means (8) to detect an angle of rotation (AC) of an engine crankshaft, and rotation speed detection means (8) for detecting an engine rotation speed (NE). The break control system is characterized by the fact that the break position control device determines a valve opening quantity (THCMD) of the inlet air flow rate control valve (3) after the operation of the shutdown device. interruption using the motor rotation speed (NE) detected by the rotation speed detection device and the rotation angle (AC) detected by the rotation angle detection device and triggers the inlet airflow rate control valve (3) so that the amount of valve opening of the airflow rate control valve matches the determined amount of valve opening (THCMD), thereby increasing the rate of incoming air flow.

With this setting, the amount of valve opening of the inlet air flow rate control valve is determined using the detected engine speed and angle of rotation

3/26 detected, the inlet air flow rate control valve being actuated so that the actual valve opening quantity matches the determined valve opening quantity, thereby increasing the air flow rate of input. Therefore, the amount of valve opening of the inlet air flow rate control valve is more appropriately configured, which makes it possible to avoid the interruption of the motor in the overlapping state with certainty.

Specifically, it is preferable to determine the amount of valve opening (THCMD) of the inflow rate control valve (3) based on the rotation angle (AC) detected by the rotation angle detection device when the detected engine speed (NE) becomes equal to or less than a predetermined speed (NES2).

With this configuration, the amount of valve opening of the inlet air flow rate control valve is determined based on the detected rotation angle when the detected motor rotation speed becomes equal to or less than a predetermined rotation speed. . Therefore, the amount of valve opening of the inlet air flow rate control valve is more appropriately configured, thus certainly avoiding engine interruption in the overlapping state.

Alternatively, the break position control device can determine the amount of valve opening (THCMD) of the inlet air flow rate control valve based on the engine speed (NE) detected by the rotation speed when the rotation angle (AC) detected by the rotation angle detection device reaches a predetermined rotation angle (CAO).

With this configuration, the amount of valve opening of the inlet air flow rate control valve is determined based on the engine's detected rotation speed when the detected rotation angle reaches the predetermined rotation angle. Therefore, the amount of valve opening of the inlet air flow rate control valve is more appropriately configured, thus avoiding the interruption of the motor in the overlapping state with certainty. Additionally, the determination of the amount of valve opening based on the speed of engine rotation makes it possible to precisely control the break position even if the friction in the engine changes due to aging, which changes the speed range of the engine where the interruption of the motor in the overlapping state is preventable.

In addition, the break position control device can retrieve a map in which the valve opening quantity (THCMD) of the inlet air flow rate control valve is configured according to the engine rotation speed (NE ) and the rotation angle (AC), to determine the amount of valve opening (THCMD) when the detected engine rotation speed (NE) is within a predetermined range (NES22-NES21).

With this configuration, the amount of valve opening of the inlet air flow rate control valve is determined by retrieving the map in which the amount of valve opening is configured according to the engine speed and angle of rotation, when the detected rotation speed of the motor is within the predetermined range. Therefore, due to the proper configuration of the map, the motor interruption in the superimposed state is avoided with certainty. In addition, the speed range of the motor in which the motor interruption in the superimposed state can be avoided can be extended. Accordingly, the control of the interruption position can be carried out precisely even if the friction on the motor changes due to aging to change the motor speed range in which the motor interruption in the superimposed state is avoidable.

In addition, it is preferable to maintain the valve opening quantity (THCMD) of the inlet air flow rate control valve (3) at the determined valve opening quantity until the engine rotation speed (NE) reaches 0.

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With this configuration, the valve opening quantity of the inlet air flow rate control valve is maintained at the determined valve opening quantity until the engine rotation speed reaches 0, which allows for the safest prevention of motor interruption in the overlap state.

Preferably, the inlet air flow rate control valve (3) is opened before the initial timing (CAIS2) of the last inlet step of a specific cylinder before the engine stops. The specific cylinder is a cylinder that is presumed to be in the compression step at the time of engine shutdown.

With this configuration, the engine interruption in the superimposed state can be avoided by increasing the amount of air supplied to the cylinder that is in the compression step in the engine interruption. In addition, the amount of air supplied to the cylinder that is in the expansion step during engine shutdown is increased, which increases the energy to suppress the engine's reverse rotation to prevent the engine from rotating in the reverse direction to the overlapping state .

Alternatively, the inlet air flow rate control valve can be opened before the initial timing (CAIS1) of the last inlet step for a specific cylinder before the engine stops. The specific cylinder is a cylinder that is assumed to be in the expansion step during engine shutdown.

With this configuration, the amount of air supplied to the cylinder that is presumed to be in the expansion step during engine shutdown increases even more, thus, an additional increase in force to suppress the engine's reverse rotation, which allows for more prevention reverse rotation of the overlapping state.

Brief Description of Drawings

Figure 1 is a schematic diagram illustrating an internal combustion engine configuration and a control system according to an embodiment of the present invention;

figure 2 shows a time graph to illustrate a general line of the interruption position control of the present invention;

figure 3 shows time graphs to illustrate the state immediately prior to the engine stop;

figure 4 is a diagram illustrating the relationship between the steps of each cylinder and the crank angle with respect to a six-cylinder engine;

figure 5 is a diagram to illustrate that the engine stop position changes depending on the engine rotation speed (NETHO) and the crank angle (CATHO) at the moment of the valve opening command of the acceleration valve;

Figure 6 illustrates the time graphs to illustrate that the shape of changes in engine speed (NE) and inlet pressure (PBA) after opening the throttle valve, changes depending on the throttle valve opening at the time the throttle valve opening command;

figure 7 shows the diagrams to illustrate that the engine stop position changes depending on the throttle valve openings (THS1, THS2) at the time of the throttle valve open command;

figure 8 is a flowchart of the interruption position control (the first modality);

figure 9 shows diagrams to illustrate the present invention in comparison with the prior art;

figure 10 shows diagrams to illustrate a method of calculating the cylinder pressure work (ECYL);

figure 11 is a flow chart to illustrate a modification of the process illustrated in figure 8;

figure 12 is a diagram to illustrate the control of the break position of the second embodiment of the present invention;

figure 13 is a flow diagram of the interruption position control (the second modality);

figure 14 is a diagram to illustrate the control of the position of

Interrupting the third embodiment of the present invention;

figure 15 is a flowchart of the interruption position control (the third modality);

figure 16 is a diagram illustrating a map referred to in the process of figure 15.

Mode of Carrying Out the Invention

Preferred embodiments of the present invention will now be described with reference to the drawings

First Mode

Figure 1 is a schematic diagram illustrating an internal combustion engine configuration and a control system according to an embodiment of the present invention. The internal combustion engine 1 (hereinafter referred to as the engine) is a 6-cylinder engine and has an inlet pipe 2 provided with an acceleration valve 3. The throttle valve 3 is provided with a throttle valve opening sensor 4 for detecting a TH opening of the throttle valve 3, and a detection signal from the throttle valve sensor 4 is supplied to an electronic control unit 5 (hereinafter referred to as ΈCU). A driver 7 for driving the throttle valve 3 is connected to the throttle valve 3, and the operation of the driver 7 is controlled by ECU 5.

A fuel injection valve 6 is provided for each cylinder in a position slightly upstream of an inlet valve (not shown) in the inlet pipe 2. Each injection valve is connected to a fuel pump (not shown) and connected electrically to the ECU 5. A valve opening period for each fuel injection valve 6 is controlled by a signal from the ECU 5. Each cylinder of the engine 1 is provided with a spark plug 9 which is connected to the ECU 5. ECU 5 supplies an ignition signal for each spark plug 9.

A crank angle position sensor 8 for detecting a rotation angle of a crankshaft (not shown) of engine 1 is connected to ECU 5 and a signal corresponding to a detected rotation angle of the crankshaft is supplied to the ECU 5. The crank angle position sensor 8 includes a cylinder discrimination sensor that sends a pulse (hereinafter referred to as a CYL pulse) in a predetermined crank angle position for the engine specific cylinder 1. The crank angle position sensor also includes an upper dead center (TDC) sensor that sends a TDC pulse at a crank angle position at a predetermined crank angle before the TDC at which the input step starts at each cylinder (that is, at each 120-degree crank angle on the six-cylinder engine) and a crank angle sensor (CRK) to generate a pulse (hereinafter referred to as the CRK pulse) at intervals of a constant crank angle period (for example, a six degree period, which is shorter than the TDC pulse generation period). The CYL pulse, the TDC pulse and the CRK pulse are supplied to ECU 5. The CYL, TDC and CRK pulses are used to control the various timings, such as the fuel injection timing and an ignition timing, and to detect an engine rotation speed NE.

An acceleration sensor 10 for detecting an amount of pressure from the accelerator pedal of the vehicle driven by engine 1 (the amount of pressure will be referred to as the amount of accelerator operation) is connected to ECU 5, and the detection signal from the acceleration 10 is supplied for ECU 5.

ECU 5 includes an input circuit having several functions including a function for formatting the waveforms of the input signals from the various sensors, a function for correcting the voltage levels of the input signals to a predetermined level, and a function converting analog signal values ​​to digital signal values. ECU 5 additionally includes a central processing unit (referred to as a CPU), a memory circuit, and an output circuit. The memory circuit preliminarily stores various operating programs to be executed by the CPU and the computation results or similar by the CPU. The output circuit supplies the trigger signals for the fuel injection valve 6 and the like. ECU 5 carries out a control over the 9/26 valve opening period of the fuel injection valve 6 and a spark ignition timing control 9 based on the sensor detection signals described above. The ECU also calculates a THCMD target opening of the throttle valve 3 and performs a trigger control of the trigger 7 so that the TH detected throttle valve opening coincides with the THCMD target opening.

Below, an overview of the piston position control by stopping the engine (the control will be referred to as the stop position control) in this mode is described below.

Figure 2 illustrates the changes in the rotation speed of the NE engine after the ignition switch is switched off at time tO, an inlet pressure PBA (inlet pressure 2 on the downstream side of the throttle valve 3), a number STG stage indicative of a crank angle position for every 30 degrees of crankshaft rotation angle, the THCMD target opening and the actual TH opening of the throttle valve. The STG stage number is configured as follows by setting the CAO reference angle position shown in figure 4 to 0 degrees. That is, the STG stage number is set to 0 when the AC crank angle is equal to or greater than 0 and less than 30 degrees, set to 1 when the AC crank angle is equal to or greater than 30 degrees and less at 60 degrees, set to 2 when the AC crank angle is 60 degrees or more and less than 90 degrees, and set to 3 when the AC crank angle is 90 degrees or more and less than 120 degrees .

In this mode, the target opening THCMD is configured according to the AC crank angle at the time (t1) when the rotation speed of the NE motor enters a predetermined speed range after the ignition switch is turned off, and the throttle valve 3 is opened so that the TH throttle valve opening coincides with the THCMD target opening. In figure 2 (c), the solid line L1 illustrates the changes in the target opening THCMD and the thin solid line L2 illustrates the changes in the opening of the TH throttle valve. By opening the valve

10/26 acceleration 3, the PBA inlet pressure increases, which, accordingly, increases a negative torque TRQN (a torque in the direction of interruption of the engine rotation) in the cylinder that is in the compression step immediately before the interruption and it also generates a positive TRQP torque in the cylinder that is in the expansion step.

A total cylinder pressure force FCYL is defined as a sum of the negative force required for the entry, compression and exhaust of gases in each cylinder of the engine and the positive force generated by the expansion of gases in each cylinder. Additionally, an ECYL cylinder pressure job is defined as a job performed by the total cylinder pressure force FCYL. The EIUNR inertial energy of the engine at time tO decreases due to the EFRC energy that is consumed by the ECYL cylinder pressure work and the FFRC friction (frictional force) of the moving parts in the engine (the EFRC energy will be referred to as the EFRC friction work) . The motor stops when the EINR inertial energy reaches 0, and the absolute value of the total cylinder pressure force FCYL becomes equal to or less than the absolute value of the FFRC friction (moment t2). In figure 2 (a), the rotation speed of the NE motor is not equal to 0 at time t2. This is because the rotation speed of the NE motor is not updated due to the repetition of the reverse and normal motor revolutions immediately before the interruption.

The PBA inlet pressure increases more rapidly at the target opening as the THCMD target opening at time t1 increases, which causes a rapid reduction in the rotation speed of the NE motor. In other words, the form of reduction in the rotation speed of the NE motor changes depending on changes in the target opening THCMD.

Figure 3 (a) illustrates changes in EINR inertial energy just before engine shutdown, and figure 3 (b) illustrates changes in total cylinder pressure force FCYL (L11) and friction FFRC (L12, L13) that are described above. As illustrated in figure 3 (b), the inertial energy EINR reaches 0 at time t11. However, the reverse rotation starts due to the FCYL full cylinder pressure force if the FCYL total cylinder pressure force is greater than the FFRC friction. Consequently, the

11/26 EINR inertial energy in the reverse direction is generated, and normal rotation and reverse rotation alternate until the EINR inertial energy reaches 0 and the absolute value of the FFRC friction (that is, until the condition in which EINR = 0 and L13 <L11 <L12 is satisfied). In the example shown in figure 3, the inertial energy EINR reaches 0 at time t12 and normal rotation starts. The inertial energy EINR reaches 0 again at time t13. At time t13, the absolute value of the total cylinder pressure force FCYL is equal to or less than the absolute value of the FFRC friction. Accordingly, the engine then stops. It should be noted that the motor stops without starting the inverted rotation if the absolute value of the total cylinder pressure force FCYL is equal to or less than the absolute value of the FFRC friction at time t11 when the inertial energy EINR first reaches 0.

Figure 4 illustrates the changes in steps in each cylinder of the six-cylinder engine. The shaded region indicates an angular crank band (hereinafter referred to as the overlap band) where the engine stops in the overlap state. In this modality, as described above, the target opening THCMD is configured according to the crank angle AC at time t1, thus avoiding interruption in the overlapping range.

Figure 5 is a diagram to illustrate that the engine stop position changes depending on a NETHO engine rotation speed (hereinafter referred to as the valve opening command rotation speed) and a CATHO crank angle (hereinafter referred to as angle valve opening handle) at the time of the valve opening command for the throttle valve 3 (moment t1 in figure 2). In figure 5, the region R1 with solid line shading corresponds to a region (hereinafter referred to as an OK region) where the motor out of the overlapping range, and the R2 and R3 regions with shading of dashed lines correspond to a region ( hereinafter referred to as the NG region) where the engine stops in the overlapping range. It should be noted that the regions R1 to R3 illustrated in figure 5 are empirically obtained by maintaining the valve opening of the throttle valve 3 at a value

12/26 constant.

For example, when the rotation speed of the NETHO valve opening command is 440 rpm and the CATHO valve opening crank angle is 30 degrees (point P2), the engine stops in the overlap range. When the rotation speed of the NETHO valve opening command is 480 rpm and the CATHO valve opening crank angle is 30 degrees (point P1), the motor is out of the overlap range. When the NETHO valve opening command rotation speed is 520 rpm and the CATHO valve opening crank angle is 30 degrees (point P3), the motor stops in the overlap range.

Therefore, if the valve opening command for the throttle valve 3 is issued in the OK R1 region shown in figure 5, the motor can be stopped outside the overlap range. However, the rotation speed of the NE engine and the AC crank angle can change as indicated by the L21 or L22 curve in figure 5 before the engine stops, depending on a relationship between the ignition switch off time and the speed. NE motor speed and AC crank angle when shutting down. In such a case, the valve opening command for the throttle valve cannot be issued in the OK R1 region, and the interruption outside the overlapping range cannot be performed.

Therefore, in this modality, by changing the opening of the throttle valve in the issue of the timing of the valve opening command to the throttle valve 3 according to the AC crank angle, the interruption outside the overlapping range is performed with certainty.

Figure 6, similarly to figure 2, illustrates changes in the rotation speed of the NE motor, PBA inlet pressure, and number of STG stages after the ignition switch is turned off. The solid lines correspond to the case in which the THCMD target opening of the throttle valve 3 is set to a first THS1 opening (for example, 17.5 degrees), and the dotted lines correspond to the case in which the THCMD target opening is. configured for a second THS2 aperture (for example, 30 degrees). When the THCMD target opening is set to the second THS2 opening, the increased velocity of the PBA inlet pressure becomes higher compared to the case in which the THCMD target opening is set to the first THS1 opening, which makes the drop in the NE motor rotation speed greater in section A shown in figure 6. Therefore, the motor stop position can be controlled to a position outside the overlap range.

Figure 7 (a) illustrates the OK region R1 and the regions NG R2 and R3 when the target opening THCMD is configured for the first opening THS1. Figure 7 (b) illustrates the OK R1 region and the NG R2 and R3 regions when the THCMD target opening is configured for the second THS2 opening. As is apparent from the comparison between figures 7a and 7b, the OK region corresponding to the second THS2 opening is switched to the higher rotational speed side compared to the OK region corresponding to the first THS1 opening. It is noted that the width of the OK region tends to become narrower as the OK region moves to the side of greater rotation speed, and converges to a certain width. In the step immediately before the engine shutdown, the difference between the absolute value of the negative force required for air compression in one cylinder and the absolute value of the positive force generated by the expansion of air in another cylinder, becomes smaller as the timing valve opening valve of the throttle valve 3 advances to the higher speed side. Consequently, the total cylinder pressure force FCYL, which is the force to control the engine stop position, decreases, to make the width of the OK region narrower. However, since the pressure on the downstream side of the throttle valve does not exceed atmospheric pressure, the width of the OK region converges to a certain width if the acceleration valve opening timing advances further to the higher speed side . On the other hand, if the valve opening timing of the throttle valve 3 is delayed to the lower speed side, the engine stops before the pressure rises on the downstream side of the throttle valve, and the width of the region OK tends to become

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Figure 7 (c) is a diagram illustrating both OK R1 regions of figures 7 (a) and 7 (b). The motor stop position can be controlled to a position outside the overlapping range by setting the THCMD target opening to the first THS1 opening when the AC crank angle is between the CAO reference angle and a CAS2 limit value (shown in figure 7 (c)) at the moment when the rotation speed of the NE motor reaches the range in the vicinity of 480 rpm, and the setting of the target opening THCMD in the second opening THS2 when the crank angle AC is greater than the limit value CAS2 at the moment when the rotation speed of the NE motor reaches the range in the vicinity of 480 rpm.

As described above, the motor interruption control of this modality is characterized by the fact that the OK regions correspond to a plurality of throttle valve openings (THS1, THS2) mutually complementing each other to deal with any form of change in the speed of engine rotation upon engine interruption. This characteristic is obtained by contemplating the following points: 1) the pressure work of the ECYL cylinder changes by changing the throttle valve opening when the throttle valve is opened immediately before the engine stops, and according to the OK region (that is, the relationship between the crank angle AC and the rotation speed of the NE engine when opening the throttle valve, and the piston position at engine stop) changes, and 2) the OK region corresponding to an opening of the throttle valve (THS1 or THS2) cannot cover (handle) all forms of change in the rotation speed of the motor by stopping the motor (that is, all the locations in the diagram characteristic of figure 5).

Figure 8 is a flow chart of the break position control described above. Stop position control is performed by the CPU on ECU 5 at predetermined time intervals (for example, 10 milliseconds) during engine 1 operation.

In step S11, it is determined whether or not permission to stop motor 1 has been granted. Specifically, it is determined whether the

15/26 ignition switch has been turned off, or the interrupt inactive command has been issued. If the interruption permission has been granted, the fuel supply to engine 1 and ignition by spark plug 9 are interrupted. In order to reduce the vibration that accompanies engine stop 1, it is preferable to keep the throttle valve in the closed position until the throttle valve is opened by the stop position control described above after the engine stop permission 1 is granted. Therefore, in this mode, when the motor 1 interruption permission is granted, the THCMD target opening of the throttle valve is set to an opening (0) of the closed position. If the answer in step S11 is negative (NO), the process is terminated immediately.

If the interruption permission is granted, the process proceeds from step S11 to step S12, where it is determined whether or not a valve opening command indicator FENGSTP is equal to 1. The valve opening command indicator FENGSTP is configured to 1 in step S17. Since the FENGSTP valve opening command indicator is initially equal to 0, the process continues to step S13.

In step S13, it is determined whether or not the engine speed NE is greater than a first predetermined speed NES1 (eg 475 rpm) and equal to or less than a second predetermined speed NES2 (eg , 485 rpm). If the answer to step S13 is negative (NO), the process is terminated. If the answer for step S13 is affirmative (YES), that is, if the NE motor rotation speed decreases to reach the second predetermined rotation speed NES2, the process proceeds to step S14, where it is determined whether or not the crank angle CA is greater than a first predetermined angle CAS1 (for example, an angle corresponding to the reference angle position CA0) and less than a second predetermined angle CAS2 (for example, CA0 + 65). If the answer to step S14 is affirmative (YES), the target opening THCMD is set to the first opening THS1 (step S15). On the other hand, if the response for step S14 is negative (NO), the target opening THCMD is set for the second

16/26 THS2 opening (step S16). It should be noted that the predetermined rotation speeds NES1 and NES2 are configured so that step S14 is performed at least once after the ignition switch is turned off.

After executing step S15 or S16, the FENGSTP valve opening command indicator is set to 1 (step S17). After that, the answer to step S12 is affirmative (YES) and the THCMD target opening that is set to THS1 or THS2 is maintained until the engine stops.

According to the process of figure 8, the configuration of the target opening THCMD and the issuing of the valve opening command of the acceleration valve 3 are carried out in the OK region indicated by the shading of figure 7 (c). Therefore, stopping the motor in the overlapping range can be avoided.

In addition, the break position (crank angle position at the time of the engine stop) is precisely controlled. Accordingly, by storing the status of the interrupted position, the relationship between each cylinder and the step (figure 4) is known by the CPU at the beginning of the next engine start. Consequently, fuel injection and ignition can be performed in an approximate manner, thus improving the initial performance of the engine.

Figure 9 is a diagram to illustrate the control method in this modality compared to the control method described in the patent document described above 1. In this modality, the control method is applied to the control of a six-cylinder engine. But the control method according to patent document 1 is applied to the control of a four-cylinder engine. Therefore, figure 9 is a diagram corresponding to the four-cylinder engine.

According to patent document 1, the idle speed control valve is fully open in the vicinity of the CAO inlet start step timing of cylinder No. 4 (indicated as THCMD in figure 9) in order to stop the engine in the compression step

17/26 of cylinder No. 4, thereby rapidly increasing the flow rate of incoming air to increase the braking force (indicated by the solid line L31) generated by the pressure of cylinder PCYL on cylinder No. 4. If defined a step in which the engine stops as the last step, the last step of cylinder No. 3 is the expansion step. The PCYL cylinder pressure in cylinder No. 3 is, as illustrated by solid lines L32, comparatively high in the previous stage of the last step and gradually decreases to generate a positive torque TRQP (indicated by solid line L41). According to the method of patent document 1, the valve opening timing of the idle speed control valve is in the vicinity of the CAO1 crank angle. Accordingly, the increase in the inlet air flow rate resulting from opening the idle speed control valve has almost no influence on the No. 3 cylinder, and the PCYL cylinder pressure is comparatively low as indicated by the solid line. L32, which makes the positive torque generated TRQP comparatively small as indicated by the solid line L41. Therefore, the angle of reverse rotation in the last step immediately prior to the engine stop becomes comparatively large, and the stop position may not be precisely controlled.

On the other hand, in this modality, the throttle valve is opened by a comparatively low opening in the CAO2 valve opening timing that is prior to the initial CAIS1 timing of the last N ° 3 cylinder inlet step immediately before the engine stop. Accordingly, the amount of air entering the cylinder No. 3 increases, and the cylinder pressure PCYL in the last expansion step increases as indicated by the dashed line L33, which causes the positive torque TRQP to increase as indicated by the dashed line L42. According to this control, it is possible to prevent the motor from turning inverted and stopping in the overlapping state, and it controls the interruption position positively. It should be noted that the timing for opening the throttle valve is preferably set before the initial timing described above CAIS1 of the input step. By setting the timing for opening the throttle valve before the initial CAIS2 timing of the last step 18 of the No. 4 cylinder inlet whose last step is the compression step, the amount of air entering the No. 3 cylinder can be increased to cause the positive torque TRQP to increase compared to the conventional method.

It should be noted that the initial input step timings described above CAIS1 and CAIS2 on the six-cylinder engine of this modality are illustrated in figure 4. The initial input step timings CAIS1 and CAIS2 shown in figure 4 correspond to the case in which the motor stops at the CASTP crank angle shown in figure 4.

The first and second predetermined rotation speeds NES1 and NES2 and the first and second predetermined angles CAS1 and CAS2 in the process of figure 8 are configured based on the characteristic diagram of figure 7 (c) which is obtained empirically. Alternatively, it is possible to obtain a diagram corresponding to the characteristic diagram of figure 7 (c) by calculation or computer simulation using the EINR inertial energy, the ECYL cylinder pressure work, and the EFRC friction work immediately after the switch. ignition switch off. These EINR, ECYL and EFRC parameters are obtained by the calculation described below:

The EINR inertial energy is calculated by the following equation (1).

EINR = (1/2) 1 · ω² (1)

In equation (1), I is the combined inertia impulse of the piston, the crankshaft, and rotatingly driven parts connected to the crankshaft of the engine 1. The inertia impulse I is a parameter that is determined in a singular way depending on the specification of motor, ω is a parameter obtained by converting the rotation speed of the NE motor into angular rotation speed.

In the following, the method of calculating the ECYL cylinder pressure work will be described with reference to figures 10 (a) to 10 (c). A force FL in the direction along the connecting rod is calculated by the following equation (2) where a length L of the connecting rod, a crank radius R, and angles φ and θ are defined as shown in figure 10 (a) .

(2)

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Equation 1

In equation (2), F is a vertically downward force generated by the cylinder pressure PCYL, which is calculated by the following equation (3).

F = PCYL X AIN - PA X AOUT

F = PCYLX AIN - PAX AOUT (3) where PA is the atmospheric pressure; and AIN and AOUT are, respectively, an area of ​​the upper piston surface and an area of ​​the lower piston surface.

Additionally, the PCYL cylinder pressure is obtained as a function of the crank angle (Θ in figure 10) using the relationships in the following equation (4) illustrated below and the initial condition that the cylinder pressure at the time the inlet ends is substantially equal to the PBA inlet pressure.

PCYL XV^k = constant (4) where V is a combustion chamber volume, and k is a polytropic index that is set to 1.3, for example.

Additionally, a force FR acting vertically for the straight line L51 passing through the center of the crankshaft illustrated in figure 10 (c) is provided by the following equation (5) using force FL. Equation (6) is obtained by applying equation (2) to equation (5). It should be noted that sin φ in equation (5) is provided by the following equation (7).

FR = FL x sin φ (5) - —sin # -sin (/ (6) (7)

Therefore, the ECYL cylinder pressure work is calculated by the following equation (8).

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ECYL = YFR-R-Ae (8)

The pressure of cylinder PCYL changes depending on the setting of the target opening THCMD in the timing of opening of the throttle valve (moment t1 in figure 2), which, consequently, changes the pressure work of cylinder ECYL.

In addition, EFRC friction work can be achieved by either of the two methods described below.

The first method is that the EFRC friction work is obtained from the torque generated by an engine (for example, a starter) when the engine is rotated.

The second method is a method as follows: an inertial energy consumed Δ E is calculated from a difference between the rotation speed ω 1 at the start of a predetermined step and the rotation speed ω 2 at the end of the predetermined step during the fuel cut operation where the fuel supply to the engine is interrupted. Next, an inter-step friction work Δ EFRC is calculated by subtracting the work of inter-step cylinder pressure Δ ECYL from the inertial energy consumed Δ E.

Specifically, the inertial energy consumed Δ E is calculated by the following equation (9) and the inter-step friction work Δ EFRC is calculated by the following equation (10).

Δ E = (1/2) 1 · ω I²- (1/2) 1 · ω 2² (9)

Δ ERFC = Δ E - Δ ECYL (10)

The crank angle AC (Θ) at which the inertial energy EINR reaches 0 and the absolute value of the total cylinder pressure force FCYL is equal to or less than the absolute value of the friction FFRC, can be calculated using the inertial energy EINR, the cylinder pressure work ECYL and friction work EFRC that are calculated, as described above. Consequently, the break position can be obtained by the calculation and the characteristic diagram as shown in figure 7 (c) can be projected from the results of the calculation.

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In this mode, the throttle valve 3 corresponds to the inlet air flow rate control valve, the crank angle position sensor 8 corresponds to the rotation angle detection device and the rotation speed detection device and ECU 5 are break devices and break position control devices.

Modification

In the mode described above, the control of the interruption position can be carried out by the process illustrated in figure 11 instead of the process illustrated in figure 8. The process in figure 11 is obtained by replacing steps S14 and S16 in figure 8, respectively, by steps S14a and S16a, and by adding steps S14b and S16b.

In step S14a, it is determined whether or not the handle angle CA is greater than the first predetermined angle CAS1 and less than a second predetermined angle CAS2a (<CAS2). If the response for step S14a is negative (NO), the crank angle CA is determined to be equal to or greater than the second predetermined angle CAS2 and less than a third predetermined angle CAS3 (step S14b). If the answer for step S14b is affirmative (YES), the target opening THCMD is set to a second opening THS2a (<THS2) (step S16a). On the other hand, if the response for step S14b is negative (NO), the target opening THCMD is set to a third opening THS3 (> THS2) (step S16b).

As described above, by setting each crank angle range to a narrower range and setting the THCMD target aperture to three different values ​​corresponding to the three angle ranges, interruption of the overlapping range can be avoided with greater certainty.

In addition, the target opening THCMD can be configured by retrieving a THS table in which a given THS opening is configured according to the AC crank angle when the response to step S13 becomes affirmative (YES). The THS table for this control is configured so that the THS configured opening

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Second Mode

Figure 12 is a characteristic diagram to illustrate the interruption position control in this mode, where the OK regions corresponding to the two THS1 and THS2 throttle valve openings are indicated similarly to figure 7 (c) described above. In this modality, the target opening THCMD is configured for the first opening THS1 or the second opening THS2 according to the rotation speed of motor NE when the crank angle CA is equal to the CAO reference angle. This modality is the same as the first modality, except for the points described below.

Figure 13 is a flowchart of the interruption position control in this mode. Figure 13 is obtained by replacing steps S13 and S14 in figure 8, respectively, by steps S22 and S23 and by adding step S21.

In step S21, it is determined whether the crank angle CA is equal or not to the CAO reference angle. In step S21, it can be determined whether the crank angle CA is in a predetermined range (CAO ψ Δ CA) whose center is the CAO reference angle.

If the answer to step S21 is negative (NO), the process is terminated immediately. If the answer to step S21 is affirmative (YES), it is determined whether the rotation speed of the NE motor is equal to or less than or a third predetermined rotation speed NES11 and equal to or greater than a fifth predetermined rotation speed NES13 (step S22). If the answer to step S22 is negative (NO), the process is immediately terminated. If the answer to step S22 is affirmative (YES), it is determined whether or not the speed of rotation of the NE motor is less than a fourth predetermined speed of rotation NES12 and equal to or greater than the fifth predetermined speed of rotation NES13 (step S23 ). It is noted that the predetermined rotation speeds NES11 and NES13 are configured so that step S23 is carried out with certainty at least once after the ignition switch is turned off23 / 26.

If the answer to step S23 is affirmative (YES), the target opening TCHMD is set to the first opening THS1 (step S15). On the other hand, if the response for step S23 is negative (NO), the target opening THCMD is set for the second opening THS2 (step S16).

The third to fifth predetermined rotation speeds described above NES11, NES12, NES13 are configured as shown in figure 12. In the OK regions, the target opening THCMD is configured for an appropriate opening by the process of figure 13, thus avoiding, with certainty , the interruption in the overlap range. Additionally, since the OK region can be extended in the direction of the motor rotation speed (the direction of the horizontal geometry axis), it is possible to accurately control the break position even if the motor friction has changed due to aging , to change the OK region in the direction of the horizontal geometric axis.

It should be noted, in this mode, that the throttle valve opening can be set to three different values ​​or more as described in the modification of the first mode.

Third Mode

Figure 14 is a characteristic diagram to illustrate the control of the interruption position of this modality, where the OK regions corresponding to the two throttle valve openings THS1 and THS2 are indicated in a similar way to figure 7 (c) described above. However, the pattern of the OK regions is slightly different from Figure 7 (c). In this mode, when the rotation speed of the NE motor is equal to or less than a sixth predetermined rotation speed NES21 and equal to or greater than a seventh predetermined rotation speed NES22, the target opening THCMD is configured for the first opening THS1 or the second THS2a opening by retrieving a THS map that is configured according to the NE motor rotation speed and the AC crank angle. This modality is the same as the first modality except for the points described below.

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Figure 15 is a flowchart for controlling the interruption position of this modality. Figure 15 is obtained by eliminating steps S14 and S16 in figure 8, and replacing steps S13 and S15, respectively, with steps S31 and S32.

In step S31, it is determined whether the engine speed NE is equal to or less than the sixth predetermined speed NES21 and equal to or greater than the seventh predetermined speed NES22. If the answer to step S31 is negative (NO), the process is terminated immediately. If the answer to step S31 is affirmative (YES), the THS map shown in figure 16 is retrieved according to the rotation speed of the NE motor and the AC crank angle, to determine a determined THS opening. Then, the target opening THCMD is set to the determined opening THS (step S32). The THS map is configured for the part surrounded by the thin dashed line in figure 14, so that the first THS1 opening or the second THS2 opening is selected according to the OK region corresponding to the first THS1 opening and the OK region corresponding to the second THS2 opening. It is noted that the predetermined rotation speeds NES21 and NES22 are configured so that step S32 is performed at least once after the ignition switch is turned off.

The sixth and seventh predetermined rotation speeds described above NES21 and NES22 are configured as shown in figure 14, and the target opening THCMD is configured for an appropriate opening in the OK regions by the process of figure 15, thus avoiding, for sure, the interruption in the overlap range. In addition, since the OK region can be extended in the direction of the motor rotation speed (the direction of the horizontal geometry axis) it is possible to carry out the precise control of the interruption position, even if the motor friction has changed due to aging , to change the OK region in the direction of the horizontal geometric axis.

In this mode, two values ​​of the first and second openings THS1 and THS2 are configured on the THS map. Alternatively, the OK25 / 26 region can be divided into three or more regions and three or more values ​​can be configured on the THS map.

The present invention is not limited to the modalities described above, and several modifications can be made. For example, the inflow rate control valve is not limited to the throttle valve. Alternatively, the idle speed control valve provided in the passage that exceeds the acceleration valve as illustrated in patent document 1, or the inlet valve (and its valve actuation mechanism) whose lift quantity and opening period are continuously changeable, can be used as the inlet air flow rate control valve.

In addition, in the modalities described above, both the fuel supply and the ignition are interrupted when the engine stop permission is granted. Alternatively, the fuel supply or the ignition may be interrupted. In addition, in the embodiments described above, examples in which the present invention is applied to the six-cylinder engine are illustrated. The present invention is also applicable to engines having any number of cylinders.

In addition, in the modalities described above, examples in which the present invention is applied to the control of the engine stop position where fuel is injected into the intake pipe, are illustrated. The present invention is also applicable to the control of the engine stop position where fuel is injected directly into the combustion chamber. In addition, the present invention can also be applied to the control of the break position of a watercraft propulsion engine such as an outboard motor having a vertical extension crankshaft.

In addition, in the embodiments described above, examples in which the crank angle position sensor 8 includes a cylinder discrimination sensor are illustrated. The cylinder distinction can be performed based on the TDC pulse and the CRK pulse. Therefore, the cylinder discrimination sensor can be omitted.

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Description of the Numerical References internal combustion engine inlet tube throttle valve (inlet air flow rate control valve) electronic control unit (interrupt device, interrupt position control device) crank (rotation angle detection device, 10 rotation speed detection device)