JP5273547B2 - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device capable of accurately computing loss torque (loss energy) when stopping rotation of an engine in a vehicle structured to transmit power of the engine to wheels through an automatic transmission. <P>SOLUTION: When stopping rotation of an engine, an ECU 30 computes the loss torque in response to a torque converter rotating speed ratio (= turbine rotating speed/engine speed) in the case (1) wherein the turbine rotating speed is higher than zero and the engine speed is higher than a predetermined rotating speed Nex, computes the loss torque in response to the engine speed in the case (2) wherein the turbine rotating speed is zero, and computes the loss torque in response to the turbine rotating speed at a time point when the engine speed becomes lower than the predetermined rotating speed Nex in the case (3) wherein the engine speed is lower than the predetermined rotating speed Nex, paying attention to that the loss torque in a torque converter 33 is changed to change the loss torque in an engine 11 by the engine speed and the turbine rotating speed of a torque converter 33. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a vehicle engine control device that transmits engine power to a wheel side via an automatic transmission having a torque converter.

  In recent years, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2008-215182) and Patent Document 2 (Japanese Patent Laid-Open No. 2008-215230), a vehicle equipped with an engine automatic stop / start system (idle stop system) Then, in order to improve restartability, engine rotation stop control is performed for the purpose of controlling the engine rotation stop crank angle to a crank angle range suitable for starting when the engine is stopped (idle stop). There is something. In the engine rotation stop control described in Patent Documents 1 and 2 above, the rotational behavior until the engine rotation stops at the target stop crank angle is calculated as a target trajectory using the loss torque obtained by adding the pumping loss and friction loss of the engine, and the engine rotation is calculated. When stopping, the load torque of the generator (alternator) is controlled so that the actual engine rotation behavior matches the target trajectory.

JP 2008-215182 A JP 2008-215230 A

  In recent years, more and more vehicles are equipped with an automatic transmission that transmits engine power to the wheels via an automatic transmission. However, in vehicles with an automatic transmission, the automatic transmission is in a power transmission state (the shift lever is driven). When the engine rotation is stopped in a state where the engine is operated by a range, etc., the influence of the automatic transmission such as the loss torque in the torque converter of the automatic transmission and the torque transmitted from the wheel side to the engine via the automatic transmission is affected. In response, the loss energy of the engine changes.

  However, in the engine rotation stop control described in Patent Documents 1 and 2, the influence of the automatic transmission such as the loss torque in the torque converter of the automatic transmission and the torque transmitted from the wheel side to the engine via the automatic transmission is completely taken into consideration. Therefore, in a vehicle with an automatic transmission, loss energy (loss torque) when stopping engine rotation cannot be accurately calculated. For this reason, the calculation accuracy of the target trajectory using the loss energy is lowered, and the engine rotation stop crank angle may not be accurately controlled within the target crank angle range.

  Therefore, the problem to be solved by the present invention is to provide an engine control device that can accurately calculate loss energy when stopping engine rotation in a vehicle with an automatic transmission.

In order to solve the above-mentioned problems, the invention according to claim 1 is applied to a vehicle that transmits engine power to a wheel side via an automatic transmission having a torque converter, and performs combustion when an engine stop request is generated. In the engine control system that stops the engine rotation by stopping, consider the influence of the automatic transmission based on the engine rotation speed and / or the turbine rotation speed of the torque converter when stopping the engine rotation in response to the generation of the engine stop request Loss energy calculating means for calculating the loss energy of the engine, and (a) when the turbine rotation speed is 0, the loss energy is calculated based on the engine rotation speed, and (b) the turbine rotation speed If There higher than a predetermined rotational speed high and the engine rotational speed than 0 is determined by the engine and the power transmission system Calculating the loss energy based on a ratio between the turbine rotational speed and the engine rotational speed, and (c) when the turbine rotational speed is higher than 0 and the engine rotational speed is equal to or lower than the predetermined rotational speed, The loss energy is calculated on the basis of the turbine rotation speed.

  When stopping the engine rotation, depending on the engine rotation speed (torque converter input shaft rotation speed) and turbine rotation speed (torque converter output shaft rotation speed), the torque converter loss torque and from the wheel side via the automatic transmission Since the torque energy transmitted to the engine changes and the engine loss energy changes, using the engine rotation speed or turbine rotation speed, the loss energy when stopping the engine rotation in consideration of the influence of the automatic transmission. Can be calculated with high accuracy.

  According to the research result of the present inventor, when the automatic transmission stops the engine rotation in the power transmission state (the shift lever is operated to the drive range or the like), (1) the turbine rotational speed is higher than 0 and When the engine rotational speed is higher than the predetermined rotational speed, the loss energy changes according to the ratio between the turbine rotational speed and the engine rotational speed. (2) When the turbine rotational speed is 0 (when the vehicle is stopped) The loss energy changes according to the engine rotation speed. (3) When the engine rotation speed is in the region below the predetermined rotation speed, the loss energy changes according to the turbine rotation speed when the engine rotation speed is below the predetermined rotation speed. It was found that there is a characteristic that the loss energy becomes almost constant with the value.

Considering such characteristics, when the turbine rotational speed is higher than 0 and the engine rotational speed is higher than the predetermined rotational speed as in the present invention , the loss energy is calculated based on the ratio between the turbine rotational speed and the engine rotational speed. calculated for way to lever, when higher and the engine rotational speed than the turbine rotation speed is 0 is region higher than a predetermined rotational speed, accuracy loss energy which varies according to the ratio of the turbine rotational speed and the engine rotational speed It can be calculated well.

Also, as in the present invention, to lever as when the turbine rotational speed of 0 calculates the loss energy based on the engine rotational speed, when the turbine rotation speed is 0, the loss that varies depending on the engine rotational speed Energy can be calculated with high accuracy.

Furthermore, as in the present invention, to lever as high and the engine rotational speed than the turbine rotation speed is zero when more than a predetermined rotational speed to calculate the loss energy based on the turbine rotational speed, the turbine rotation speed is 0 when even higher and the engine rotational speed in the following areas a predetermined rotational speed, to accurately calculate the loss energy becomes substantially constant at a value corresponding to the turbine speed when the engine rotational speed is equal to or lower than a predetermined rotational speed Can do.

Further, as in claim 2 , the loss energy may be corrected in accordance with the temperature of the hydraulic oil (automatic transmission fluid) of the automatic transmission. In this way, the viscosity (fluidity) of the hydraulic oil changes according to the temperature of the hydraulic oil in the automatic transmission, and in response to this, loss torque in the torque converter and transmission from the wheel side to the engine via the automatic transmission Corresponding to the change in engine loss energy due to a change in torque or the like, the engine loss energy can be appropriately corrected, and the calculation accuracy of the engine loss energy can be further improved.

The engine loss energy calculated by the inventions according to claims 1 and 2 described above is used for, for example, engine rotation stop control for controlling the engine rotation stop position to the target stop position, or the loss energy is taken into consideration. For example, the engine rotation stop position may be estimated, the estimated engine rotation stop position may be determined as the initial start position, and ignition / fuel injection control at the start may be performed. Is possible.

When the present invention is applied to engine rotation stop control, for example, as in claim 3 , the rotation behavior until the engine rotation is stopped at the target stop crank angle using the loss energy calculated by the loss energy calculation means (hereinafter referred to as the rotation energy). (Referred to as “target trajectory”) may be calculated by the target trajectory calculation means, and the engine auxiliary load may be controlled by the stop control means so that the actual engine rotation behavior matches the target trajectory when the engine rotation is stopped. . In this way, the target trajectory can be accurately calculated using the loss energy calculated with high accuracy, and the auxiliary load of the engine (for example, the load torque of the alternator) is adjusted to match the actual engine rotational behavior to the target trajectory. By performing the engine rotation stop control for controlling the engine rotation stop crank angle, the engine rotation stop crank angle can be accurately controlled within the target crank angle range, and the accuracy of the engine rotation stop control can be improved.

FIG. 1 is a schematic configuration diagram of an entire engine control system according to an embodiment of the present invention. FIG. 2 is a time chart for explaining the idle stop control. FIG. 3 is a time chart for explaining the engine rotation stop control. FIG. 4 is a diagram for explaining the loss torque characteristics. FIG. 5 is a flowchart for explaining the processing flow of the engine rotation stop control main routine. FIG. 6 is a flowchart for explaining the processing flow of the loss torque calculation routine. FIG. 7 is a flowchart for explaining the processing flow of the target trajectory calculation routine. FIG. 8 is a flowchart for explaining the flow of processing of the engine rotation stop control routine. FIG. 9 is a diagram illustrating an example of a first base loss torque map. FIG. 10 is a diagram illustrating an example of a second base loss torque map. FIG. 11 is a diagram illustrating an example of a third base loss torque map. FIG. 12 is a diagram illustrating an example of a correction coefficient map.

Hereinafter, an embodiment embodying a mode for carrying out the present invention will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.
An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake pipe pressure sensor 19 for detecting the intake pipe pressure is provided in the surge tank 18. The surge tank 18 is provided with an intake manifold 20 that introduces air into each cylinder of the engine 11, and fuel injection that injects fuel toward the intake port 12 in the vicinity of the intake port of the intake manifold 20 of each cylinder. A valve 21 is attached. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with a catalyst 24 such as a three-way catalyst that purifies the exhaust gas, and an exhaust gas sensor that detects the air-fuel ratio or rich / lean of the exhaust gas upstream of the catalyst 24. 25 (air-fuel ratio sensor, oxygen sensor, etc.) are provided.

  A cooling water temperature sensor 26 for detecting the cooling water temperature is attached to the cylinder block of the engine 11. A crank angle sensor 29 that outputs a pulse signal every time the crankshaft 28 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 28. Based on the output signal of the crank angle sensor 29, the crank angle and the engine speed Is detected.

  The rotation of the crankshaft 28 is transmitted to the alternator 31 via a belt mechanism (not shown). Thereby, the alternator 31 is rotationally driven by the power of the engine 11 to generate power. The load torque of the alternator 31 can be controlled by duty-controlling the power generation control current (field current) of the alternator 31.

  The power of the engine 11 is transmitted to the wheel side via the automatic transmission 32. The automatic transmission 32 includes a torque converter 33, a transmission mechanism 34, and the like, and a turbine rotational speed of the torque converter 33 (an output shaft rotational speed of the torque converter 33) is detected by a turbine rotational speed sensor 35. The speed change mechanism 34 may be a stepped speed change mechanism that switches a speed step among a plurality of speed steps, or may be a CVT (stepless transmission) that changes continuously.

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

  Further, the ECU 30 executes an engine automatic stop / start control routine (not shown), as shown in FIG. 2, in a predetermined deceleration state (for example, accelerator fully closed, brake on) that may cause the vehicle to stop while the vehicle is running. When the engine stop request is generated in a state where all the conditions equal to or less than the predetermined vehicle speed are satisfied, idle stop is executed to stop the engine rotation by stopping combustion (ignition and / or fuel injection). Thereafter, when the driver performs an operation to start the vehicle (for example, release of the brake operation, depression of the accelerator, operation of the shift lever to the drive range, etc.) and an engine start request is generated, or battery charge control When an engine start request is generated from a control system of an in-vehicle device such as a system or an air conditioner, the starter (not shown) is energized to crank and restart the engine 11.

  Further, the ECU 30 executes the routines for engine rotation stop control shown in FIGS. 5 to 8 described later to stop the engine rotation in response to the generation of the engine stop request as shown in FIG. At each predetermined control timing (for example, every TDC), a loss torque is calculated as information on the loss energy of the engine 11, and the rotation behavior until the engine rotation stops at the target stop crank angle using the loss torque (hereinafter referred to as "target trajectory"). The engine rotation stop control is executed to control the load torque of the alternator 31 so that the actual engine rotation behavior matches the target trajectory.

  Here, the target trajectory is calculated by assigning a relationship between the crank angle to the target stop crank angle and the target engine speed at a predetermined crank angle interval (for example, TDC interval) and assigning it to a table (not shown). Yes, it is calculated and updated every predetermined control timing (for example, every TDC). This target trajectory is calculated, for example, in the direction of increasing the crank angle using the target stop crank angle as an initial value, using a relational expression of an energy conservation law considering the loss torque of the engine 11.

The relational expression of the energy conservation law is expressed by the following expression.
Ne (i + 1) ² = Ne (i) ² −2 / J × {Tloss (θ (i)) − Tref (Ne (i))}
Here, Ne (i + 1) is the engine speed at the time (i + 1) before the current crank angle (i), Ne (i) is the engine speed at the current time (i), and J is the engine speed. 11 moment of inertia. Tloss (θ (i)) is the loss torque of the engine 11 at the crank angle θ (i) at the current time (i), and Tref (Ne (i)) is the engine speed Ne (i) at the current time (i). The reference load torque of the alternator 31 in FIG. In this embodiment, the reference load torque Tref (Ne (i)) of the alternator 31 is set to half (1/2) of the maximum load that can be controlled by the alternator 31.

  During engine rotation stop control, the base load torque is calculated so as to reduce the deviation between the target engine speed and the actual engine speed at the current crank angle θ (i) obtained from the target trajectory. The required load torque Talt is obtained by adding the reference load torque Tref (Ne (i)) to the load torque (actually, this required load torque Talt is multiplied by the pulley ratio Ratio to convert it to the required shaft torque Talt.final. ).

  Thereafter, using the load torque characteristic of the alternator 31, the required load torque Talt (required shaft torque Talt.final) of the alternator 31 and the engine rotational speed Ne (or the engine rotational speed Ne) are multiplied by the pulley ratio Ratio. A power generation command value (duty duty) corresponding to the rotation speed Nalt of the alternator 31 is calculated. Based on the power generation command value (duty duty), the power generation control current (field current) of the alternator 31 is controlled to control the load torque of the alternator 31.

  Such control of the load torque of the alternator 31 is periodically executed at a predetermined crank interval until the engine speed decreases to the power generation limit rotational speed Nelow of the alternator 31 or less, thereby matching the actual engine rotational behavior to the target trajectory. Thus, engine rotation stop control for feedback control of the load torque of the alternator 31 is performed.

  By the way, in a vehicle that transmits the power of the engine 11 to the wheel side via the automatic transmission 32, when the automatic transmission 32 stops the engine rotation in a power transmission state (a state in which the shift lever is operated to the drive range or the like). Furthermore, the loss torque of the engine 11 changes under the influence of the automatic transmission 32 such as the loss torque in the torque converter 33 of the automatic transmission 32 and the torque transmitted from the wheel side to the engine 11 via the automatic transmission 32.

  Therefore, in this embodiment, when the engine rotation is stopped, the influence of the automatic transmission 32 is based on the engine rotation speed (the input shaft rotation speed of the torque converter 33) and the turbine rotation speed (the output shaft rotation speed of the torque converter 33). The loss torque of the engine 11 is calculated in consideration of the above.

  According to the research result of the present inventor, as shown in FIG. 4, it has been found that the loss torque of the engine 11 when the automatic transmission 32 stops the engine rotation in the power transmission state has the following characteristics. . Hereinafter, the ratio between the turbine rotational speed and the engine rotational speed is referred to as “torque rotational speed ratio” (torque rotational speed ratio = turbine rotational speed / engine rotational speed).

  (1) When the turbine rotational speed is higher than 0 and the engine rotational speed is higher than the predetermined rotational speed Nex (0 <torque rotational speed ratio <predetermined value X), the loss torque changes according to the torque converter rotational speed ratio. .

  (2) When the turbine rotational speed is 0 (torque rotational speed ratio = 0), the loss torque changes according to the engine rotational speed.

  (3) When the engine speed is in a region where the engine rotational speed is equal to or lower than the predetermined rotational speed Nex (torque converter rotational speed ratio ≧ predetermined value X), the loss torque is a value corresponding to the turbine rotational speed when the engine rotational speed is equal to or lower than the predetermined rotational speed Nex. Becomes almost constant.

  Here, the predetermined rotational speed Nex is a value determined by a power transmission system such as the engine 11 or the automatic transmission 32, and the predetermined value X is a torque converter rotational speed ratio at which the engine rotational speed becomes the predetermined rotational speed Nex.

  In consideration of such characteristics, in this embodiment, when the automatic transmission 32 stops the engine rotation in the power transmission state, the loss torque of the engine 11 is calculated as follows.

  (1) When the turbine rotational speed is higher than 0 and the engine rotational speed is higher than the predetermined rotational speed Nex (0 <torque rotational speed ratio <predetermined value X), map the loss torque according to the torque converter rotational speed ratio or By calculating with a mathematical formula or the like, the loss torque that changes in accordance with the torque converter rotational speed ratio is accurately calculated.

  (2) When the turbine rotational speed is 0 (torque converter rotational speed ratio = 0), the loss torque that changes according to the engine rotational speed is accurately calculated by calculating the loss torque according to the engine rotational speed using a map or a mathematical expression. To do.

  (3) When the engine rotational speed is in a region where the rotational speed of the engine is equal to or less than the predetermined rotational speed Nex (the torque converter rotational speed ratio ≧ predetermined value X), the loss torque is mapped according to the turbine rotational speed when the engine rotational speed is equal to or smaller than the predetermined rotational speed Nex. Alternatively, the loss torque that is substantially constant at a value corresponding to the turbine rotation speed at the time when the engine rotation speed becomes equal to or lower than the predetermined rotation speed Nex is calculated with high accuracy by calculating with mathematical formulas or the like.

  When stopping the engine rotation when the automatic transmission 32 is in a non-power transmission state (a state in which the shift lever is operated to the neutral range or the like), for example, a loss torque corresponding to the crank angle is calculated using a map or a mathematical expression. Thus, the loss torque obtained by adding the pumping loss and the friction loss of the engine 11 is calculated.

  The engine rotation stop control described above is executed by the engine ECU 30 in accordance with the routines for engine rotation stop control shown in FIGS. The processing contents of these routines will be described below.

[Engine rotation stop control main routine]
The engine rotation stop control main routine shown in FIG. 5 is repeatedly executed at a predetermined cycle while the engine ECU 30 is powered on. When this routine is started, first, at step 101, it is determined whether or not an engine stop request (idle stop signal) has been generated. If no engine stop request has been generated, the subsequent processing is not performed. This routine ends.

  Thereafter, when it is determined in step 101 that an engine stop request has been generated, the process proceeds to step 102 to determine whether or not the current crank angle θ is the load torque control timing (for example, TDC) of the alternator 31. However, if the control timing of the load torque of the alternator 31 is not reached, this routine is terminated without performing the subsequent processing.

  Thereafter, if it is determined in step 102 that the current crank angle θ is the control timing of the load torque of the alternator 31, the process proceeds to step 103 to execute a loss torque calculation routine of FIG. The loss torque of the engine 11 at the angle θ is calculated.

  Thereafter, the process proceeds to step 104, a target trajectory calculation routine shown in FIG. 7 described later is executed, and the target trajectory is calculated using the loss torque calculated in the loss torque calculation routine shown in FIG. 8 is executed, and the load torque of the alternator 31 is feedback-controlled so that the actual engine rotational behavior matches the target trajectory.

[Ross torque calculation routine]
The loss torque calculation routine shown in FIG. 6 is a subroutine executed in step 103 of the engine rotation stop control main routine of FIG. 5, and serves as loss torque calculation means in the claims. When this routine is started, first, in step 201, a torque converter rotation speed ratio, which is a ratio between the turbine rotation speed and the engine rotation speed, is calculated.

Torcon rotational speed ratio = turbine rotational speed / engine rotational speed Thereafter, the routine proceeds to step 202, where it is determined whether the turbine rotational speed is higher than 0 (whether the torque converter rotational speed ratio is larger than 0). If it is determined that the rotational speed is higher than 0, the routine proceeds to step 203, where it is determined whether or not the engine rotational speed is higher than a predetermined rotational speed Nex.

  If it is determined in step 202 that the turbine rotational speed is higher than 0, and if it is determined in step 203 that the engine rotational speed is higher than the predetermined rotational speed Nex, the routine proceeds to step 204 and shown in FIG. The base loss torque corresponding to the torque converter rotation speed ratio is calculated with reference to the first base loss torque map. This first base loss torque map is set so that the base loss torque decreases as the torque converter rotational speed ratio increases. The first base loss torque map is created in advance based on test data, design data, and the like, and is stored in the ROM of the ECU 30.

  On the other hand, if it is determined in step 202 that the turbine rotation speed is 0 or less (that is, the turbine rotation speed is 0), the routine proceeds to step 205, where the second base loss torque map shown in FIG. The base loss torque according to the engine rotation speed is calculated with reference to FIG. This second base loss torque map is set so that the base loss torque decreases as the engine speed decreases. The second base loss torque map is created in advance based on test data, design data, and the like, and is stored in the ROM of the ECU 30.

  If it is determined in step 203 that the engine rotation speed is equal to or lower than the predetermined rotation speed Nex, the process proceeds to step 206, and the engine rotation speed is determined with reference to the third base loss torque map shown in FIG. A base loss torque corresponding to the turbine rotational speed at the time when the speed becomes equal to or less than the predetermined rotational speed Nex is calculated. The third base loss torque map is set such that the base loss torque decreases as the turbine rotation speed at the time when the engine rotation speed becomes equal to or lower than the predetermined rotation speed Nex. The third base loss torque map is created in advance based on test data, design data, and the like, and is stored in the ROM of the ECU 30.

  After calculating the base loss torque in this way, the process proceeds to step 207, and referring to the correction coefficient map shown in FIG. 12, correction according to the temperature of the hydraulic oil (automatic transmission fluid) of the automatic transmission 32 is performed. Calculate the coefficient. The correction coefficient map is set so that the correction coefficient increases and the loss torque increases as the temperature of the hydraulic oil of the automatic transmission 32 decreases. The correction coefficient map is created in advance based on test data, design data, and the like, and is stored in the ROM of the ECU 30.

Thereafter, the process proceeds to step 208, where the base loss torque is corrected using the correction coefficient to determine the final loss torque of the engine 11.
Loss torque = Base loss torque x Correction factor

[Target trajectory calculation routine]
The target trajectory calculation routine shown in FIG. 7 is a subroutine executed in step 104 of the engine rotation stop control main routine of FIG. 5, and serves as target trajectory calculation means in the claims. When this routine is started, first, in step 301, using the loss torque Tloss (θ (i)) and the reference load torque Tref (Netg (i)) of the alternator 31, the energy conservation law expressed by the following equation is obtained. The square of the target engine speed Netg (i + 1) at the next time point (i + 1) is calculated using the relational expression.

Netg (i + 1) ² = Netg (i) ² −2 / J × {Tloss (θ (i)) − Tref (Netg (i))}
Here, the loss torque Tloss (θ (i)) uses the loss torque calculated in the routine of FIG. The initial values are i = 0, θ (0) = target stop crank angle, and Netg (0) = 0 rpm (engine speed at stop). The target trajectory is calculated in the direction of turning the crank angle with the target stop crank angle θ (0) as an initial value.

  Thereafter, in step 302, the square root of the target engine rotational speed Netg (i + 1) is calculated to obtain the target engine rotational speed Netg (i + 1), and this is stored in a target trajectory table (not shown). Assign. In order to reduce the calculation load on the ECU 30, the square of the target engine speed Netg (i + 1) may be assigned to the table as it is. The target trajectory table is stored in the memory of the ECU 30.

  Thereafter, the process proceeds to step 303, where it is determined whether or not the square of the target engine rotational speed Netg (i + 1) exceeds the square of the maximum engine rotational speed Nemax that can execute the engine rotational stop control. If it does not exceed the square of Nemax, the routine returns to step 301, the square of the target engine rotational speed Netg (i + 1) is calculated in the direction of increasing the crank angle, and the target engine rotational speed Netg (i + 1) is entered in the target trajectory table. ) Is repeated. When it is determined in step 303 that the square of the target engine rotational speed Netg (i + 1) exceeds the square of the maximum engine rotational speed Nemax that can execute the engine rotational stop control, this routine is terminated.

[Engine rotation stop control routine]
The engine rotation stop control routine shown in FIG. 8 is a subroutine executed in step 105 of the engine rotation stop control main routine shown in FIG. 5, and serves as stop control means in the claims. When this routine is started, first, at step 401, it is determined whether or not the current engine speed Ne is lower than the maximum engine speed Nemax that can execute the engine rotation stop control, and the current engine speed Ne is determined. Is equal to or greater than the maximum engine speed Nemax, the routine is terminated without performing the subsequent processing.

  On the other hand, if it is determined in step 401 that the current engine speed Ne is lower than the maximum engine speed Nemax, the process proceeds to step 402, and the target trajectory table is referred to at the current control timing. The corresponding target engine speed Netg is obtained.

  Thereafter, the routine proceeds to step 403, where the required load torque Talt is calculated by the following equation using the current engine speed Ne, the target engine speed Netg, and the reference load torque Tref (Ne) of the alternator 31.

Here, J is the moment of inertia of the engine 11, K is the feedback gain, and Δθ is the crank angle change amount.
Thereafter, the process proceeds to step 404, where the required load torque Talt is multiplied by the pulley ratio Ratio to convert it to the required shaft torque Talt.final of the alternator 31.

  Thereafter, the process proceeds to step 405, and after detecting the battery voltage, the process proceeds to step 406, and a load torque characteristic map corresponding to the current battery voltage is selected from a plurality of load torque characteristic maps created for each battery voltage. Then, a power generation command value (duty duty) corresponding to the current required load torque Talt (required shaft torque Talt.final) and the engine rotational speed Ne (or the rotational speed Nalt of the alternator 31) is calculated.

  In the present embodiment described above, when the automatic transmission 32 stops the engine rotation in a power transmission state (a state where the shift lever is operated to the drive range or the like), the torque converter 33 depends on the engine rotation speed and the turbine rotation speed. Paying attention to the loss torque of the engine 11 and the torque transmitted from the wheel side to the engine 11 via the automatic transmission 32 changes, and the loss torque of the engine 11 changes. 11 is calculated, the loss torque at the time of stopping the engine rotation can be accurately calculated in consideration of the influence of the automatic transmission 32.

  Further, since the target trajectory is calculated using this loss torque, the target trajectory can be calculated with high accuracy, and the engine rotation for controlling the load torque of the alternator 31 to match the actual engine rotational behavior with the target trajectory. Since the stop control is performed, the engine rotation stop crank angle can be accurately controlled within the target crank angle range, and the accuracy of the engine rotation stop control can be improved.

  In the above embodiment, when the engine rotation is stopped, the loss torque of the engine 11 is calculated at a predetermined control timing (for example, every TDC) based on the engine rotation speed and the turbine rotation speed at that time, and the control timing. Every time, the target trajectory is calculated and updated using the loss torque at that time, but the present invention is not limited to this. For example, when the engine rotation is stopped, the engine rotation is performed at the first control timing (for example, TDC). The turbine rotation speed at each control timing (for example, every TDC) until the engine stops is predicted, and the engine 11 at each control timing is based on the predicted value of the turbine rotation speed at each control timing at the first control timing. The target trajectory may be calculated by predicting the loss torque.

  In the above-described embodiment, the load torque of the alternator 31 is controlled so that the actual engine rotational behavior matches the target trajectory at the time of engine rotation stop control. However, the present invention is not limited to this, and auxiliary equipment other than the alternator For example, loads such as an air conditioner compressor and a hybrid vehicle generator may be controlled.

  In the above embodiment, the present invention is applied to a system for executing engine rotation stop control, and the target trajectory is calculated using the loss energy (loss torque) of the engine 11 calculated based on the engine rotation speed and the turbine rotation speed. However, the scope of application of the present invention is not limited to a system that executes engine rotation stop control. For example, an engine that takes into account the loss energy of the engine 11 calculated based on the engine rotation speed or the turbine rotation speed is considered. It is possible to estimate the rotation stop crank angle (rotation stop position), determine the estimated engine rotation stop crank angle as the initial crank angle, and perform ignition / fuel injection control at the start, etc. You may change suitably the utilization method of the loss energy of the engine 11 calculated based on the speed and the turbine rotational speed.

  In addition, the present invention is not limited to a general vehicle having only an engine as a power source of the vehicle, and may be applied to a hybrid vehicle having an engine and a motor as a power source of the vehicle. Needless to say, various modifications can be made within the range.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 29 ... Crank angle sensor, 30 ... ECU (loss energy calculation means, target) (Trajectory calculation means, stop control means), 31 ... alternator, 32 ... automatic transmission, 33 ... torque converter, 34 ... transmission mechanism, 35 ... turbine rotation speed sensor

Claims (3)

In an engine control device that is applied to a vehicle that transmits engine power to a wheel side via an automatic transmission having a torque converter, and stops engine rotation by stopping combustion when an engine stop request is generated,
When the engine rotation is stopped in response to the generation of the engine stop request, the engine loss energy is calculated in consideration of the influence of the automatic transmission based on the engine rotation speed and / or the turbine rotation speed of the torque converter. A loss energy calculating means,
The loss energy calculation means (a) calculates the loss energy based on the engine rotation speed when the turbine rotation speed is 0, and (b) the turbine rotation speed is higher than 0 and the engine rotation speed When the speed is higher than a predetermined rotational speed determined by the engine and the power transmission system, the loss energy is calculated based on a ratio between the turbine rotational speed and the engine rotational speed, and (c) the turbine rotational speed is greater than zero. And the loss energy is calculated based on the turbine rotational speed when the engine rotational speed is equal to or lower than the predetermined rotational speed.   The engine control apparatus according to claim 1, wherein the loss energy calculation means includes means for correcting the loss energy in accordance with a temperature of hydraulic oil of the automatic transmission. Target trajectory calculating means for calculating rotational behavior (hereinafter referred to as “target trajectory”) until engine rotation stops at a target stop crank angle using the loss energy calculated by the loss energy calculating means;
The engine according to claim 1, further comprising: a stop control unit that controls an auxiliary machine load of the engine so that an actual engine rotation behavior is matched with the target trajectory when the engine rotation is stopped. Control device.

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