JP2006057524A - Engine revolution stopping control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control the stop position of engine revolution. <P>SOLUTION: Revolving energy for every TDC is calculated in an engine revolution stopping process to calculate a revolving energy variation (energy consumption) between the TDC, and a relationship between the energy consumption and an engine speed is used to estimate engine revolution stopping behavior. At a timing determined in accordance with the estimated engine revolution stopping behavior, stop position control (alternator load control, e.g.) is executed to force engine revolution to be stopped at a target stop position. Thus, with no influences of a dispersion of a revolving energy consuming speed due to the manufacturing tolerance of an engine, a secular change and an engine friction change, the stop position control is executed at a consistently proper timing, therefore permitting accurate control of the stop position of the engine revolution, finding accurate information for the stop position of the engine revolution and improving startability and starting exhaust emission. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine rotation stop control device having a function of controlling a stop position of engine rotation.

  In general, during engine operation, the cylinder is discriminated based on the output signals of the crank angle sensor and the cam angle sensor and the crank angle is detected to perform ignition control and fuel injection control. There is a problem that the cylinder to be initially ignited / injected is unknown until the starter cranks the engine and completes the determination of the specific cylinder (that is, until a signal of a predetermined crank angle of the specific cylinder is detected).

  In order to solve this problem, as described in Japanese Patent Laid-Open No. 60-240875, a crank angle (stop position of the crankshaft) when the engine rotation is stopped is stored in a memory. During the next engine start, until the first crank angle signal for a specific cylinder is detected, ignition control and fuel injection control are started based on the crank angle at the time of engine rotation stop stored in the memory. By doing so, there are those that improve the startability and exhaust emission at the start.

  However, even after the ignition switch is turned off and the ignition and fuel injection are stopped, the engine rotates by inertia for a while. Therefore, if the crank angle at the time of turning off the ignition switch is stored, the actual engine stop position ( The next engine start position) is erroneously determined. Therefore, even after the ignition switch is turned off, it is necessary to continue the detection of the crank angle by keeping the power supply of the control system on until the engine rotation is completely stopped, but the compression stroke is just before the engine rotation stops. Therefore, the engine stop position cannot be detected accurately (reverse rotation cannot be detected).

Further, as described in Patent Document 2 (Japanese Patent Application Laid-Open No. 11-107823), the crankshaft is inertial based on the engine operating state (intake pipe pressure, engine rotation speed) at the moment when the ignition switch is turned off. The engine rotation is calculated by calculating the amount of rotation (TDC number) until the engine stops and the engine is rotated from the cylinder in which the fuel is injected immediately before the ignition switch is turned off and the amount of rotation (TDC number) until the engine is stopped. There is an engine in which the first cylinder in the sequential injection at the next engine start is estimated.
JP-A-60-240875 (2nd page etc.) Japanese Patent Application Laid-Open No. 11-107823 (page 2, etc.)

  By the way, when the engine rotation is stopped, inertial kinetic energy (rotational energy) of the engine is consumed due to a pumping loss, a friction loss, and the like, and the engine rotational speed is lowered and stopped as the rotational energy decreases. For this reason, engine rotation is stopped due to variations in rotational energy consumption speed (amount of change in rotational energy per predetermined period) due to engine manufacturing tolerances, changes over time, engine friction changes (for example, differences in viscosity due to changes in engine oil temperature, etc.) The behavior varies.

  However, in the technology of Patent Document 2, only the rotational energy consumption speed in the engine rotation stop process is stored by matching in advance, and the change of the rotation energy is not predicted in the actual engine rotation stop process. Estimation of the amount of rotation (number of TDCs) until the crankshaft rotates due to inertia and stops due to variations in rotational energy consumption speed due to engine manufacturing tolerances, changes over time, and changes in engine friction (that is, variations in engine rotation stop behavior) May be wrong. For this reason, it is difficult for the technique of Patent Document 2 to accurately estimate the stop position of the engine rotation. As a result, the initial injection cylinder and ignition cylinder at the time of engine start are erroneously determined, Exhaust emissions during start-up may be exacerbated.

  The present invention has been made in consideration of such circumstances. Accordingly, the object of the present invention is to accurately control the stop position of engine rotation, and to improve startability and exhaust emission at the time of start. Another object of the present invention is to provide an engine rotation stop control device that can be operated.

  In order to achieve the above object, an engine rotation stop control device according to claim 1 of the present invention is a system for stopping engine rotation by stopping ignition and / or fuel injection based on an engine stop command. Stop position control means for executing stop position control for controlling the stop position of the engine, and stop position control timing determination means for determining timing for executing stop position control based on a change in engine rotational energy in the engine rotation stop process. The stop position control is executed at the timing determined by the stop position control timing determining means to control the stop position of the engine rotation.

  If the execution timing of stop position control is determined based on changes in rotational energy during the engine rotation stop process, variations in rotational energy consumption speed due to engine manufacturing tolerances, changes over time, and changes in engine friction (that is, variations in engine rotation stop behavior) ), The stop position control can always be executed at an appropriate timing. As a result, the stop position of the engine rotation can be controlled with high accuracy, and information on the stop position of the engine rotation (information on the initial position of the crankshaft at the start of the engine) can be obtained with high accuracy. The exhaust emission at the time can be improved.

  Specifically, as in claim 2, the amount of change in rotational energy between predetermined crank angles (for example, between TDCs) is calculated in the engine rotation stop process, and the engine rotation stop behavior ( It is preferable to estimate the engine rotation stop position reaching the engine rotation stop position) and determine the stop position control execution timing based on the engine rotation stop behavior. In this way, the engine rotation stop behavior can be accurately estimated in consideration of changes in the actual rotational energy consumption speed (the amount of change in rotational energy between predetermined crank angles) during the engine rotation stop process. It is possible to execute the stop position control at an appropriate timing according to the stop behavior (for example, a timing immediately before stopping the engine rotation).

  In this case, as in claim 3, it is preferable to calculate the amount of change in rotational energy between predetermined crank angles using at least one of the engine rotational speed, crankshaft angular speed, and piston moving speed. The engine rotational speed, the crankshaft angular speed, and the piston moving speed are all parameters that change according to the engine rotational energy. Therefore, if at least one of these parameters is used, the amount of change in rotational energy between predetermined crank angles. Can be calculated with high accuracy.

  Further, as in the fourth aspect, the engine rotation speed at the predetermined crank angle immediately before the engine rotation stop position and the engine rotation stop position are estimated using the relationship between the engine rotation speed and the amount of change in rotational energy between the predetermined crank angles. Good.

  Using the relationship between the amount of change in rotational energy between predetermined crank angles and the engine speed, the amount of change in rotational energy between the next predetermined crank angles can be predicted from the actually measured engine speed, and the amount of change in rotational energy. Thus, the rotational energy at the next predetermined crank angle and thus the engine rotational speed can be predicted. In the process of stopping the engine rotation, the process of predicting the engine rotation speed at the next predetermined crank angle is repeated in this manner, and the predicted value of the engine rotation speed becomes less than the predetermined value, so that the next compression TDC cannot be overcome. When determined, it can be estimated that the engine rotation stops before the compression TDC. In this way, the engine rotation speed and the engine rotation speed at a predetermined crank angle immediately before the engine rotation stop can be estimated, so that the timing for executing the stop position control can be accurately determined using these pieces of information. it can.

  Further, when the stop position control is executed, the stop position of the engine rotation may be controlled by controlling the load torque of the auxiliary machine driven by the engine. Since the load torque of the auxiliary machine acts in a direction that hinders engine rotation, the stop position of the engine rotation can be controlled by controlling the load torque of the auxiliary machine.

  In this case, as in claim 6, it is preferable to control the load torque of the generator by controlling the power generation amount of the generator as an auxiliary machine. If it does in this way, the stop position of engine rotation can be accurately controlled by the energization control of the generator.

  Further, as in claim 7, when the stop position control is executed, the stop position of the engine rotation may be controlled by controlling the compression pressure in the compression stroke. Since the compression pressure in the compression stroke acts in a direction that hinders engine rotation, the stop position of the engine rotation can be controlled by controlling the compression pressure in the compression stroke.

  In this case, as in claim 8, it is preferable to increase the amount of intake air in the intake stroke immediately before stopping the engine rotation to increase the compression pressure in the next compression stroke. In this way, it is possible to increase the compression pressure in the compression stroke by using a means for controlling the intake air amount (for example, an idle rotation speed control valve, an electronic throttle valve), and even for the current engine control system. The present invention can be implemented only by changing the control program.

  Further, in an engine equipped with a variable valve mechanism, the intake air amount is increased in the intake stroke immediately before stopping the engine rotation by changing the opening / closing timing or the lift amount of the intake valve of the engine as in claim 9. Also good. Since the intake valve is provided at the intake port of each cylinder, the intake air amount filled in the cylinder is increased with good response without considering the response delay until the air that has passed through the throttle valve is sucked into the cylinder. The compression pressure at the time of stop can be increased with high accuracy.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the following three embodiments.

A first embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of the engine control system will be schematically described with reference to FIG. A throttle valve 14 is provided in the middle of the intake pipe 13 connected to the intake port 12 of the engine 11, and an opening degree (throttle opening degree) TA of the throttle valve 14 is detected by a throttle opening degree sensor 15. The intake pipe 13 is provided with a bypass passage 16 that bypasses the throttle valve 14, and an idle speed control valve (hereinafter referred to as “ISC valve”) 17 is provided in the middle of the bypass passage 16. An intake pipe pressure sensor 18 for detecting the intake pipe pressure PM is provided on the downstream side of the throttle valve 14, and a fuel injection valve 19 is attached in the vicinity of the intake port 12 of each cylinder.

  On the other hand, an exhaust gas purifying catalyst 22 is installed in the middle of the exhaust pipe 21 connected to the exhaust port 20 of the engine 11. The cylinder block of the engine 11 is provided with a coolant temperature sensor 23 that detects the coolant temperature THW. A crank angle sensor 26 is installed facing the outer periphery of the signal rotor 25 attached to the crankshaft 24 of the engine 11. The crank angle sensor 26 synchronizes with the rotation of the signal rotor 25 from the crank angle sensor 26 at every predetermined crank angle (for example, 10 ° C.). A crank pulse signal CRS is output every A). A cam angle sensor 29 is installed opposite to the outer periphery of the signal rotor 28 attached to the cam shaft 27 of the engine 11, and the cam pulse is generated at a predetermined cam angle in synchronization with the rotation of the signal rotor 28 from the cam angle sensor 29. Signal CAS is output.

  The rotation of the crank pulley 34 connected to the crankshaft 24 is transmitted to the alternator 33 (generator) via the belt 35. Thereby, the alternator 33 is rotationally driven by the power of the engine 11 to generate power.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and controls the fuel injection amount and injection timing of the fuel injection valve 19 and the ignition timing of the spark plug 31 according to the engine operating state detected by various sensors, and also during engine operation. When an ignition switch OFF signal or an idle stop signal (idle stop command) is input to, ignition and / or fuel injection are stopped to stop the engine rotation.

  At that time, the ECU 30 calculates the rotational energy E for each TDC in the process of stopping the engine rotation to calculate the amount of change in the rotational energy E (energy consumption ELOSS) between the TDCs. The energy consumption ELOSS and the engine rotational speed are calculated. The stopping behavior of the engine rotation is estimated using the relationship with NE. Then, the execution timing of stop position control (for example, alternator load control) is determined based on the estimated engine rotation stop behavior, and the stop position control is executed at that timing to control the stop position of engine rotation. Information on the engine rotation stop position at that time (for example, the stroke state of each cylinder when the engine is stopped) is stored in a rewritable non-volatile memory such as the backup RAM 32, and this engine stop position storage information is stored at the next engine start. Use to start fuel injection control and ignition control.

Here, details of the engine rotation stop control of the first embodiment will be described.
First, the estimation method of the engine rotation stop behavior will be described using the time chart of FIG. Hereinafter, the instantaneous engine rotation speed (hereinafter referred to as “instantaneous rotation speed”) in the i-th compression TDC (i) is referred to as NE (i). The ECU 30 calculates the instantaneous rotation speed NE (i) by measuring the time required for the crankshaft 24 to rotate, for example, by 30 ° C. from the output interval of the crank pulse signal CRS.

In the first embodiment, when the instantaneous rotational speed NE (i) at TDC (i) is calculated, the instantaneous rotational speed NE (i + 1) at the next TDC (i + 1) is predicted as follows. To do.
First, the rotational energy E that is the inertial operating energy of the engine 11 is calculated for each TDC.
E (i) = J × {NE (i)} ² (1)
Here, J is a coefficient corresponding to the moment of inertia determined for each engine.

The difference between the rotational energy E (i-2) at TDC (i-2) and the rotational energy E (i-1) at TDC (i-1) is obtained from TDC (i-2) to TDC (i -1) to calculate the energy consumption ELOSS (i-1), and the difference between the rotational energy E (i-1) at TDC (i-1) and the rotational energy E (i) at TDC (i) To calculate the energy consumption ELOSS (i) between TDC (i-1) and TDC (i).
ELOSS (i-1) = E (i-2) -E (i-1) (2)
ELOSS (i) = E (i-1) -E (i) (3)

Thereafter, a coefficient K representing the relationship between the energy consumption ELOSS (change amount of the rotational energy E) between the TDCs and the instantaneous rotational speed NE is obtained by the following equation.
K (i) = {ELOSS (i-1) -ELOSS (i)} / {NE (i-1) -NE (i)}
...... (4)

On the other hand, using the energy consumption ELOSS (i + 1) between TDC (i) and TDC (i + 1), the relationship of the above equation (4) can be replaced with the relationship of the following equation (5). .
K (i + 1) = {ELOSS (i) −ELOSS (i + 1)} / {NE (i) −NE (i + 1)}
...... (5)

Further, the energy consumption ELOSS (i + 1) between TDC (i) and TDC (i + 1) can be expressed as the following equation (6).
ELOSS (i + 1) = E (i) −E (i + 1) (6)

The following equation (7) can be derived by erasing ELOSS (i + 1) using the above equation (5) and (6).
E (i + 1) = E (i) − [ELOSS (i) −K (i + 1) × {NE (i) −NE (i + 1)}]
...... (7)

However, since the future rotational speed NE (i + 1) is necessary in the above equation (7), [K (i + 1) × {NE (i) −NE (i + 1) in the above equation (7). }] Is replaced with the previous value [K (i) × {NE (i-1) −NE (i)}], whereby the above expression (7) can be replaced with the following expression (8). .
E (i + 1) = E (i) − [ELOSS (i) −K (i) × {NE (i−1) −NE (i)}]
...... (8)
Furthermore, the following formula (9) can be derived from the formula (1) and the formula (8).

According to the above (9), when the instantaneous rotational speed NE (i) at TDC (i) is calculated, the instantaneous rotational speed NE (i + 1) at the next TDC (i + 1) can be predicted.
In the process of stopping the engine rotation, a process of predicting the instantaneous rotational speed NE (i + 1) at the next TDC (i + 1) in this way and comparing the predicted value with a preset stop determination value NETDC is performed. Repeatedly, when the predicted value of the instantaneous rotational speed NE (i + 1) becomes equal to or less than the stop determination value NETDC, the engine rotation cannot overcome the next compression TDC of TDC (i + 1), and TDC (i It is determined that the engine rotation is stopped before the next compression TDC of +1), and TDC (i + 1) where the predicted value of the instantaneous rotational speed NE (i + 1) is equal to or less than the stop determination value NETDC is stopped. It is estimated as the immediately preceding TDC (hereinafter referred to as “TDC ⁰ ”), and the predicted value of the instantaneous rotational speed NE (i + 1) is estimated as the estimated instantaneous rotational speed netdc ⁰ at TDC ⁰ . Then, the predicted value of the instantaneous rotational speed NE (i) one time before the estimated instantaneous rotational speed netdc at the TDC one time before TDC ⁰ immediately before stopping the engine rotation (hereinafter referred to as “TDC ⁻¹ ”) is used. Estimated to be ^-1 .

Next, a method for controlling the engine rotation stop position will be described using the time chart of FIG. In the process of stopping the engine rotation, when the instantaneous rotational speed NE decreases to near the estimated instantaneous rotational speed netdc ^-1 at TDC ^-1 just before TDC ⁰ immediately before the engine rotational stop, the ISC valve 17 is fully opened (Duty = 100%), and increasing the intake air amount of the engine 11 to increase the compression pressure of the next compression stroke, assists the forced stop of the engine rotation. In the control example of FIG. 3, by increasing the intake air amount in the intake stroke of the # 3 cylinder, the compression pressure of the # 3 cylinder that increased the intake air amount in the next stroke is increased, and the force that impedes engine rotation is increased. Let

Thereafter, the alternator load control is executed when the instantaneous rotational speed NE decreases to near the estimated instantaneous rotational speed netdc ⁰ at TDC ⁰ immediately before the engine rotation is stopped. In this alternator load control, the load torque of the alternator 33 is controlled by controlling the power generation amount of the alternator 33, and the engine rotation is forcibly stopped at a target stop position θ (for example, BTDC 90 ° C. A).

  The engine rotation stop behavior estimation and the engine rotation stop position control of the first embodiment described above are executed by the ECU 30 according to the programs of FIGS. Hereinafter, the processing contents of each of these programs will be described.

[Estimation of engine rotation stop behavior]
The engine rotation stop behavior estimation program shown in FIG. 4 is activated for each TDC and plays a role as engine rotation stop behavior estimation means in the claims. When this program is started, first, in steps 101 to 103, it is determined whether or not an engine rotation stop control execution condition is satisfied. The engine rotation stop control execution conditions include, for example, the following conditions (1) to (3).

(1) The throttle valve 14 is fully closed and the throttle opening TA is not more than a predetermined value (for example, 1.5 deg or less) and the idle switch is turned on (step 101). (2) Idle stop request or ignition An engine stop command is generated by turning off the switch (step 102).
(3) The condition that both fuel injection and ignition are stopped and the engine rotation is reduced and stopped is satisfied (step 103).

If these conditions (1) to (3) are all satisfied, the engine rotation stop control execution condition is satisfied, and if any one of the conditions is not satisfied, the engine rotation stop control execution condition is not satisfied.
If the engine rotation stop control execution condition is not satisfied, that is, if “No” is determined in any of Steps 101 to 103, the program is terminated as it is.

  On the other hand, if the engine rotation stop control execution condition is satisfied, that is, if all the determinations in steps 101 to 103 are “Yes”, the process proceeds to step 104 to execute a coefficient K calculation program in FIG. Thus, the instantaneous rotational speed NE (i) at TDC (i), the energy consumption ELOSS (i) from TDC (i-1) to TDC (i), and the energy consumption ELOSS (rotational energy between TDCs) A coefficient K representing the relationship between the change amount of E) and the instantaneous rotational speed NE is calculated.

  Thereafter, the routine proceeds to step 105, where the instantaneous rotational speed NE (i) at TDC (i), the energy consumption ELOSS (i) from TDC (i-1) to TDC (i), and the coefficient K (i ) Is used to predict the instantaneous rotational speed NE (i + 1) at the next TDC (i + 1) according to the equation (9).

  Thereafter, the routine proceeds to step 106, where it is determined whether or not the predicted value of the instantaneous rotational speed NE (i + 1) at TDC (i + 1) is equal to or less than the stop determination value NETDC (for example, 300 rpm). As a result, when it is determined that the predicted value of the instantaneous rotational speed NE (i + 1) at TDC (i + 1) is larger than the stop determination value NETDC, the engine rotation is the next to TDC (i + 1). It is determined that the rotation continues over the compression TDC, and the routine proceeds to step 107, where the count value i of the calculation counter is incremented (i = i + 1), and then the instantaneous rotational speed NE (i + 1) at TDC (i + 1). And the process of determining whether or not the predicted value is equal to or smaller than the stop determination value NETDC (steps 104, 105, and 106) is repeated.

Thereafter, when it is determined in step 106 that the predicted value of the instantaneous rotational speed NE (i + 1) at TDC (i + 1) is equal to or less than the stop determination value NETDC, the engine speed is TDC (i + 1). It is determined that the engine rotation is stopped before the next compression TDC after TDC (i + 1), and the routine proceeds to step 108 where the instantaneous rotational speed NE (i + 1) TDC (i + 1) where the predicted value is equal to or smaller than the stop determination value NETDC is estimated as TDCTDC ⁰ immediately before the engine rotation is stopped, and the predicted value of the instantaneous rotational speed NE (i + 1) is set as the estimated instantaneous rotational speed netdc at TDC ⁰ . Estimated ⁰ .

Thereafter, the routine proceeds to step 109, where the predicted value of the instantaneous rotational speed NE (i) one time before is calculated as the estimated instantaneous rotational speed netdc ^-1 at TDC ^-1 one time before TDC ⁰ immediately before the engine rotation is stopped. Estimate and end this program.

[Calculation of coefficient K]
The coefficient K calculation program shown in FIG. 5 is a subroutine executed in step 104 of FIG. When this program is started, first, in step 201, the time required for the crankshaft 24 to rotate, for example, by 30 ° C. is measured from the output interval of the crank pulse signal CRS to calculate the instantaneous rotational speed NE (i). Thereafter, the process proceeds to step 202, where the rotational energy E (i) is calculated.
E (i) = J × {NE (i)} ²

  Thereafter, the process proceeds to step 203, where the difference between the instantaneous rotational speed NE (i-2) at the previous TDC (i-2) and the instantaneous rotational speed NE (i-1) at the current TDC (i-1) is stopped. It is determined whether or not the engine rotation stop behavior is being performed depending on whether or not it is greater than the behavior determination value NEDOWN (eg, 50 rpm).

As a result, if it is determined that the engine rotation stop behavior is in progress, the routine proceeds to step 204, where the energy consumption ELOSS (i-1) from TDC (i-2) to TDC (i-1) and TDC An energy consumption amount ELOSS (i) between (i-1) and TDC (i) is calculated.
ELOSS (i-1) = E (i-2) -E (i-1)
ELOSS (i) = E (i-1) −E (i)

The processing in step 204 serves as a rotational energy change amount calculation means in the claims.
Thereafter, the process proceeds to step 205, and a coefficient K representing the relationship between the energy consumption amount ELOSS (change amount of the rotational energy E) between the TDCs and the instantaneous rotational speed NE is obtained by the following equation.
K (i) = {ELOSS (i-1) -ELOSS (i)} / {NE (i-1) -NE (i)}

[Engine rotation stop position control]
The engine rotation stop position control program shown in FIG. 6 is started for each TDC. When this program is started, first, at step 301, it is determined whether or not the engine rotation is stopped. At this time, for example, whether or not the engine rotation is stopped is determined based on whether or not the crank angle signal CRS from the crank angle sensor 26 is input to the ECU 30 for a predetermined time (for example, 300 ms) or longer.

  If the engine rotation has stopped, “Yes” is determined in step 301, and this program is terminated without performing the subsequent processing. On the other hand, if the engine rotation has not stopped, “No” is determined in step 301, and the processing after step 302 is executed as follows.

  First, in steps 302 to 304, it is determined whether or not an engine rotation stop control execution condition is satisfied. The process of determining whether or not the engine rotation stop control execution condition is satisfied (the process of steps 302 to 304) is the same as the process of steps 101 to 103 of FIG.

  If the engine rotation stop control execution condition is not satisfied, that is, if “No” is determined in any of steps 302 to 304, the process proceeds to step 312 and the control value of the ISC valve 17 is calculated by the normal idle rotation speed control. After the target value DISC (ISC valve duty = DISC) is set, the routine proceeds to step 313 where the rotation stop control execution flag XPONCNT is maintained (or reset) to “0”, and at step 314, the stop position control execution flag is set. XFRICNT is maintained at “0” (or reset), and this program ends.

On the other hand, when the engine rotation stop control execution condition is satisfied, that is, when all the determinations in steps 302 to 304 are “Yes”, the process proceeds to step 305 and the current instantaneous rotation speed NE (i) and the engine The instantaneous rotational speed depends on whether or not the absolute value of the difference between the estimated instantaneous rotational speed netdc ^-1 at TDC ^-1 immediately before TDC ⁰ immediately before the rotation stop is equal to or less than a judgment value JUDGTDC ^-1 (for example, 50 rpm). It is determined whether or not NE (i) has decreased to the vicinity of the estimated instantaneous rotational speed netdc- ¹ .

When it is determined in step 305 that the instantaneous rotational speed NE (i) has decreased to near the estimated instantaneous rotational speed netdc ⁻¹ , the process proceeds to step 306, where the control value of the ISC valve 17 is forcibly fully opened (ISC valve (Duty = 100%) and the intake air amount of the engine 11 is increased to increase the compression pressure of the next compression stroke, and then the routine proceeds to step 307 where the rotation stop control execution flag XPONCNT is set to the ISC valve 17 Is set to “1” which means that the rotation stop control has been executed.

Thereafter, the routine proceeds to step 308, where the absolute value of the difference between the current instantaneous rotational speed NE (i) and the estimated instantaneous rotational speed netdc ⁰ at TDC ⁰ immediately before the engine rotation is stopped is equal to or smaller than a determination value JUDGTDC ⁰ (for example, 50 rpm). It is determined whether or not the instantaneous rotational speed NE (i) has decreased to near the estimated instantaneous rotational speed netdc ⁰ depending on whether or not there is.

When it is determined in step 308 that the instantaneous rotational speed NE (i) has decreased to near the estimated instantaneous rotational speed netdc ⁰ , the process proceeds to step 309 to execute an alternator load control program shown in FIG. The load torque of the alternator 33 is controlled by controlling the power generation amount 33, and the engine rotation is forcibly stopped at the target stop position θ.

In this case, the processing of step 305 and step 308 plays a role as stop position control timing determining means in the claims.
Thereafter, the process proceeds to step 310, where the stop position control execution flag XFRICNT is set to “1” which means that the stop position control by the alternator 33 has been executed. Information on cylinders stopped in the stroke and cylinders stopped in the compression stroke) is stored in the backup RAM 32.

[Alternator load control]
The alternator load control program shown in FIG. 7 is a subroutine executed in step 309 in FIG. 6 and plays a role as stop position control means in the claims. When this program is started, first, in step 401, the required torque TORCAL required to rotate the engine rotation to the target stop position θ (for example, BTDC 90 ° C. A) (that is, the engine rotation is stopped at the target stop position θ). Is calculated by the following equation using the measured instantaneous rotational speed NETDC ⁰ at TDC ⁰ immediately before the engine rotation is stopped and the target stop position θ.
TORCAL = J / θ × (NETDC ⁰ ) ²

  Thereafter, the process proceeds to step 402, the instantaneous rotational speed NE (i) is calculated, and then the process proceeds to step 403. Based on the change amount of the instantaneous rotational speed NE [eg, NE (i) −NE (i−1)]. The current engine torque ENGTOR is calculated.

Thereafter, the process proceeds to step 404, where the difference between the engine torque ENGTOR and the required torque TORCAL is set as the target load torque ALTTOR of the alternator 33.
ALTTOR = ENGTOR-TORCAL
Thus, the target load torque ALTTOR of the alternator 33 is set so that the value obtained by subtracting the target load torque ALTTOR of the alternator 33 from the engine torque ENGTOR becomes the required torque TORCAL.

  Thereafter, the process proceeds to step 405, and a target power generation amount for realizing the target load torque ALTTOR of the alternator 33 is set. In general, as shown in FIG. 8, the load torque of the alternator 33 changes according to the engine rotational speed NE and the amount of power generation. Therefore, the current instantaneous rotational speed NE is considered in consideration of the load torque characteristics of the alternator 33. A target power generation amount corresponding to the target load torque ALTTOR is calculated by a map or a mathematical expression.

  Thereafter, the process proceeds to step 406, and the load torque of the alternator 33 is controlled to the target load torque ALTTOR by controlling the power generation amount of the alternator 33 to the target power generation amount. Thus, the value obtained by subtracting the load torque (= target load torque ALTTOR) of the alternator 33 from the engine torque ENGTOR is set to be the required torque TORCAL, and the engine rotation is forcibly stopped at the target stop position θ.

  In the first embodiment described above, during the engine rotation stop process, the rotational energy E is calculated for each TDC, and the amount of change in the rotational energy E (energy consumption ELOSS) between TDCs is calculated. The stopping behavior of the engine rotation is estimated using the relationship with the engine rotation speed NE. Then, the execution timing of the stop position control (alternator load control in the first embodiment) is determined based on the estimated engine rotation stop behavior, and the stop position control is executed at that timing to force the engine rotation at the target stop position θ. Stop.

  Thus, if the execution timing of stop position control is determined based on the amount of change in rotational energy E (energy consumption amount ELOSS) between TDCs during the engine rotation stop process, it depends on engine manufacturing tolerances, changes over time, and changes in engine friction. Stop position control can always be executed at an appropriate timing with respect to the engine rotation stop behavior without being affected by variations in the rotational energy consumption speed (that is, variations in engine rotation stop behavior). Thereby, the stop position of the engine rotation can be controlled with high accuracy, and startability and exhaust emission at the time of start can be improved. Further, the stop position control can prevent the engine rotation from stopping at TDC (top dead center), thereby reducing the torque required at the time of starting the engine. From this aspect, the startability can be improved.

  In general, in the engine rotation stop process, the engine friction changes in accordance with the engine rotation speed and the rotation energy consumption speed (the amount of change in rotation energy per predetermined period) changes. In order to estimate the stopping behavior of the engine rotation using the relationship between the change amount of the rotational energy E (energy consumption amount ELOSS) and the instantaneous rotational speed NE, the engine is taken into account the change of the rotational energy consumption rate in the engine rotation stopping process. The rotation stop behavior can be accurately estimated.

  Further, in the first embodiment, alternator load control is executed as stop position control, and the power generation amount of the alternator 33 is controlled to control the load torque of the alternator 33 to control the stop position of the engine rotation. Therefore, the load torque of the alternator 33 can be accurately controlled to stop the engine rotation at the target stop position with high accuracy.

Next, Embodiment 2 of the present invention will be described with reference to FIGS. 9 and 10.
In the first embodiment, when the instantaneous rotational speed NE decreases to the vicinity of the estimated instantaneous rotational speed netdc ^{−1 in the} process of stopping the engine rotation, the ISC valve 17 is set to fully open, and the intake air amount of the engine 11 is increased. Although the forced stop of the engine rotation is assisted by increasing the compression pressure in the next compression stroke, in the second embodiment, the instantaneous rotational speed NE is in the vicinity of the estimated instantaneous rotational speed netdc ⁻¹ in the engine rotational stop process. When the pressure decreases to the maximum, engine speed control is executed. In this engine rotation speed control, the load torque of the alternator 33 is controlled by controlling the power generation amount of the alternator 33 so that the instantaneous rotation speed NE at TDC ⁰ immediately before the engine rotation stops becomes the target instantaneous rotation speed TARNETDC ^0. Control.

The processing contents of the engine rotation stop position control program of FIG. 9 and the engine rotation speed control program of FIG. 10 executed by the ECU 30 in the second embodiment will be described below.
In the engine rotation stop position control program shown in FIG. 9, first, in step 501, it is determined whether or not the engine rotation is stopped. If the engine rotation is not stopped, the engine rotation stop control execution condition is determined in steps 502 to 504. Whether or not is established is determined. The process of determining whether or not the engine rotation stop control execution condition is satisfied (the process of steps 502 to 504) is the same as the process of steps 101 to 103 of FIG.

  If the engine rotation stop control execution condition is not satisfied, the routine proceeds to step 512, where the rotation speed control execution flag XFLINECNT is maintained (or reset) to “0”, and at step 513, the stop position control execution flag XFRICNT is set to “0”. ”(Or reset) to end the program.

On the other hand, if the engine rotation stop control execution condition is satisfied, the routine proceeds to step 505, where it is determined whether or not the instantaneous rotational speed NE (i) has decreased to near the estimated instantaneous rotational speed netdc ^−1. When it is determined that the speed NE (i) has decreased to near the estimated instantaneous rotational speed netdc ⁻¹ , the process proceeds to step 506 and an engine rotational speed control program shown in FIG. 10 described later is executed to reduce the power generation amount of the alternator 33. By controlling, the load torque of the alternator 33 is controlled so that the instantaneous rotational speed NE at TDC ⁰ immediately before stopping the engine rotation becomes the target instantaneous rotational speed TARNETDC ⁰ .

Thereafter, the process proceeds to step 507, where the rotational speed control execution flag XFLINECNT is set to “1” which means that the rotational speed control by the alternator 33 has been executed. Thereafter, the process proceeds to step 508, where it is determined whether or not the instantaneous rotational speed NE (i) has decreased to the vicinity of the estimated instantaneous rotational speed netdc ⁰ , and the instantaneous rotational speed NE (i) has decreased to the vicinity of the estimated instantaneous rotational speed netdc ^0. When it is determined that the operation has been performed, the process proceeds to step 509, the alternator load control program of FIG. 7 is executed, the power generation amount of the alternator 33 is controlled to control the load torque of the alternator 33, and the engine rotation is stopped as a target. Forcibly stop at position θ.

  Thereafter, the process proceeds to step 510, where the stop position control execution flag XFRICNT is set to “1” which means that the stop position control by the alternator 33 has been executed, and then the process proceeds to step 511, where information on the stop position of the engine rotation (for example, intake air Information on cylinders stopped in the stroke and cylinders stopped in the compression stroke) is stored in the backup RAM 32.

In the engine rotational speed control program of FIG. 10 executed in step 506 of FIG. 9, in step 601, a request necessary for controlling the instantaneous rotational speed NE at TDC ⁰ immediately before the engine rotational stop to the target instantaneous rotational speed TARNETDC ^0. torque Torcal, using the measured instantaneous rotation speed NETDC ^-1 in one more time before TDC ^-1 of TDC ⁰ of the engine rotation stop immediately before the target instantaneous rotational speed TARNETDC ⁰ at TDC ⁰ of the engine rotation stop immediately before the following formula Calculated by
TORCAL = J / π × (NETDC ⁻¹ ) ² −J / π × (TARNETDC ⁰ ) ²

  Thereafter, the process proceeds to step 602, and after calculating the instantaneous rotational speed NE (i), the process proceeds to step 603, where the change amount of the instantaneous rotational speed NE [for example, NE (i) −NE (i−1)] is determined. The current engine torque ENGTOR is calculated.

Thereafter, the process proceeds to step 604, where the difference between the engine torque ENGTOR and the required torque TORCAL is set as the target load torque ALTTOR of the alternator 33.
ALTTOR = ENGTOR-TORCAL
Thus, the target load torque ALTTOR of the alternator 33 is set so that the value obtained by subtracting the target load torque ALTTOR of the alternator 33 from the engine torque ENGTOR becomes the required torque TORCAL.

  Thereafter, the process proceeds to step 605, where the target power generation amount for realizing the target load torque ALTTOR of the alternator 33 is calculated by calculating the target power generation amount according to the current instantaneous rotational speed NE and the target load torque ALTTOR by a map or a mathematical formula. Set.

Thereafter, the process proceeds to step 606, and the load torque of the alternator 33 is controlled to the target load torque ALTTOR by controlling the power generation amount of the alternator 33 to the target power generation amount. Thus, the value obtained by subtracting the load torque (= target load torque ALTTOR) of the alternator 33 from the engine torque ENGTOR is set so as to be the required torque TORCAL, and the instantaneous rotational speed NE at TDC ⁰ immediately before the engine rotation is stopped is the target instantaneous Control is performed so that the rotational speed becomes TARNETDC ⁰ .

In the second embodiment described above, when the instantaneous rotational speed NE (i) decreases to near the estimated instantaneous rotational speed netdc ⁻¹ in the engine rotation stop process, the load torque of the alternator 33 is controlled to stop the engine rotation. The load on the alternator 33 is controlled when the instantaneous rotational speed NE (i) decreases to near the estimated instantaneous rotational speed netdc ⁰ after controlling the instantaneous rotational speed NE at the immediately preceding TDC ^{0 to} be the target instantaneous rotational speed TARNETDC ^0. Since the torque is controlled and the engine rotation is forcibly stopped at the target stop position θ, the accuracy of the engine rotation stop position control can be further improved.

In the third embodiment of the present invention, when the engine 11 is stopped by executing the idle rotation speed control program shown in FIG. 11, the target instantaneous rotation speed TARNETDC ⁰ at TDC ⁰ immediately before the engine rotation is stopped, and the previous engine based on the difference between the measured instantaneous rotation speed PASTNETDC ⁰ at TDC ⁰ immediately before the rotation stop by correcting the idling rotational speed, so that the instantaneous rotational speed NETDC at TDC ⁰ of the engine rotation stop just before the desired instantaneous speed TARNETDC ⁰ To control.

The processing contents of the idle rotation control program of FIG. 11 executed by the ECU 30 in the third embodiment will be described below. When this program is started, first, in step 701, the previous idle rotation speed PASTNE is read, and then the process proceeds to step 702, where the measured instantaneous rotation speed PASTNETDC ⁰ at TDC ⁰ immediately before the previous engine rotation stop is read.

Then, the procedure proceeds to step 703, the target instantaneous rotational speed TARNETDC ⁰ at TDC ⁰ of the engine rotation stop immediately before, the difference between the actual measurement instantaneous rotational speed PASTNETDC ⁰ at TDC ⁰ of previous engine rotation stop immediately before the correction value [Delta] NE.
TARNETDC ⁰ −PASTNETDC ⁰ = ΔNE

Thereafter, the routine proceeds to step 704, where the correction value ΔNE is added to the previous idle rotational speed PASTNE to obtain the target idle rotational speed TARNE.
PASTNE + ΔNE = TARNE

Thereafter, the process proceeds to step 705, where the ISC valve 17 is controlled so that the idle rotation speed becomes the target idle rotation speed TARNE. Thus, the idle rotation speed is corrected so that the instantaneous rotation speed NETDC at TDC ⁰ immediately before the engine rotation stops becomes the target instantaneous rotation speed TARNETDC ⁰ .

  Thereafter, the process proceeds to step 706 to stop both the fuel injection and ignition to stop the engine rotation, and then proceeds to step 707 to proceed to step 707 for information on the stop position of the engine rotation (for example, the cylinder and the compression stroke stopped in the intake stroke). Information on the stopped cylinder) is stored in the backup RAM 32.

In the third embodiment described above, the idle rotation speed is corrected so that the instantaneous rotation speed NETDC at TDC ⁰ immediately before stopping the engine rotation is controlled to be the target instantaneous rotation speed TARNETDC ^0. The stop position of the engine can be accurately controlled, and information on the stop position of the engine rotation can be obtained with high accuracy.

  In each of the first and second embodiments, the load torque of the alternator 33 is controlled to control the stop position of the engine rotation. However, the present invention is not limited to the alternator 33, and other supplements driven by the engine 11 are also possible. You may make it control the stop position of an engine rotation by controlling the load torque of a machine (for example, a compressor of an air conditioner, a water pump, an oil pump, etc.).

  Further, by using means for controlling the intake air amount (for example, ISC valve, electronic throttle valve, variable valve mechanism, etc.), the intake air amount is increased in the intake stroke immediately before the engine rotation is stopped, and the next compression stroke is performed. The stop position of engine rotation may be controlled by increasing the compression pressure. In this way, the present invention can be implemented only by changing the control program for the current engine control system.

  For example, the intake valve opening / closing timing or lift amount may be changed immediately before the engine rotation is stopped, and the intake air amount may be increased in the intake stroke immediately before the engine rotation is stopped. Since the intake valve is provided at the intake port of each cylinder, the amount of intake air charged into the cylinder can be increased with good response without considering the delay in response of air, and the compression pressure at the time of stopping can be increased with high accuracy.

  In the first and second embodiments, the amount of change in rotational energy (energy consumption) between TDCs is calculated based on the engine rotational speed (instantaneous rotational speed). However, the present invention is not limited only to the engine rotational speed. The amount of change in rotational energy during TDC may be calculated using at least one of the engine rotational speed, the crankshaft angular speed, and the piston moving speed.

It is a schematic block diagram of the whole engine control system in Example 1 of this invention. It is a time chart explaining the estimation method of an engine rotation stop behavior. It is a time chart explaining the control method of an engine rotation stop position. It is a flowchart which shows the flow of a process of the engine rotation stop behavior estimation program of Example 1. FIG. 6 is a flowchart illustrating a flow of processing of a coefficient K calculation program according to the first embodiment. It is a flowchart which shows the flow of a process of the engine rotation stop position control program of Example 1. FIG. It is a flowchart which shows the flow of a process of the alternator load control program of Example 1. It is a load torque characteristic figure of an alternator. It is a flowchart which shows the flow of a process of the engine rotation stop position control program of Example 2. It is a flowchart which shows the flow of a process of the engine speed control program of Example 2. It is a flowchart which shows the flow of a process of the idle rotational speed control program of Example 3.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine, 13 ... Intake pipe, 14 ... Throttle valve, 17 ... ISC valve, 19 ... Fuel injection valve, 21 ... Exhaust pipe, 26 ... Crank angle sensor, 29 ... Cam angle sensor, 30 ... ECU (stop position control means) , Stop position control timing determination means, rotational energy change amount calculation means, engine rotation stop behavior estimation means), 33 ... alternator (generator)

Claims (9)

In an engine rotation stop control device that stops ignition by stopping ignition and / or fuel injection based on an engine stop command,
Stop position control means for executing stop position control for controlling the stop position of engine rotation;
An engine rotation stop control device comprising: stop position control timing determining means for determining a timing for executing the stop position control based on a change in engine rotation energy in an engine rotation stop process. A rotational energy change amount calculating means for calculating a change amount of rotational energy between predetermined crank angles in the engine rotation stop process;
Engine rotation stop behavior estimation means for estimating engine rotation stop behavior based on the amount of change in rotational energy between predetermined crank angles calculated by the rotation energy change amount calculation means,
2. The engine rotation stop according to claim 1, wherein the stop position control timing determination unit determines an execution timing of the stop position control based on the engine rotation stop behavior estimated by the engine rotation stop behavior estimation unit. Control device.   3. The rotational energy change amount calculating means calculates a rotational energy change amount between predetermined crank angles using at least one of an engine rotational speed, a crankshaft angular speed, and a piston moving speed. The engine rotation stop control device described.   The engine rotation stop behavior estimation means estimates the engine rotation speed at a predetermined crank angle immediately before the engine rotation stop position and the engine rotation stop using the relationship between the amount of change in rotational energy between the predetermined crank angles and the engine rotation speed. The engine rotation stop control device according to claim 2 or 3, characterized by the above.   5. The stop position control means controls a stop position of engine rotation by controlling a load torque of an auxiliary machine driven by an engine when the stop position control is executed. The engine rotation stop control device according to any one of the above.   The said stop position control means controls the load torque of this generator by controlling the electric power generation amount of the generator which is the said auxiliary machine, when performing the said stop position control. Engine rotation stop control device.   The said stop position control means controls the stop position of an engine rotation by controlling the compression pressure of a compression stroke, when performing the said stop position control. Engine rotation stop control device.   The stop position control means, when executing the stop position control, increases an intake air amount in an intake stroke immediately before stopping engine rotation, and increases a compression pressure in a next compression stroke. The engine rotation stop control device according to claim 7.   The stop position control means, when executing the stop position control, changes the opening / closing timing or lift amount of the intake valve of the engine to increase the intake air amount in the intake stroke immediately before stopping the engine rotation. The engine rotation stop control device according to claim 8.

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