JP5234513B2 - Torque control device for internal combustion engine - Google Patents

Description

  The present invention relates to a torque control device for an internal combustion engine having a function of controlling a torque adjustment parameter so as to realize a target torque of the internal combustion engine.

  As a torque control device for an internal combustion engine, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2002-221068), the estimated torque is corrected based on the target torque and the estimated torque of the internal combustion engine. Some estimate torques are obtained and the ignition timing is corrected in a direction to reduce the deviation between the target torque and the corrected estimated torque, thereby correcting the excess or deficiency of the torque while eliminating the influence of system variations.

Japanese Patent Laid-Open No. 2002-221068 (second page, etc.)

  However, in the system that always corrects the ignition timing so as to reduce the deviation between the target torque and the corrected estimated torque, as in the torque control device of Patent Document 1, the corrected estimated torque is reduced by the error of the torque estimation model. However, even if it is slightly increased, the ignition timing is retarded to reduce the torque, so that the torque generation efficiency is lowered and the fuel consumption may be deteriorated.

  The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide a torque control device for an internal combustion engine that can improve fuel efficiency by suppressing a decrease in torque generation efficiency. There is.

In order to achieve the above-mentioned object, the invention according to claim 1 is arranged so as to realize the target torque based on the estimated torque at the basic ignition timing of the internal combustion engine (hereinafter referred to as “basic estimated torque”) and the target torque. in the torque control device of the adjustment parameters (e.g., ignition timing, etc.) internal combustion engine having a torque control means for controlling the larger permissible torque upper limit value than goals torque (e.g. upper limit of the allowable range of the actual torque with respect to the target torque) The first feature is that the torque control means prohibits the torque adjustment parameter from being controlled in the torque decreasing direction when the basic estimated torque is equal to or less than the allowable torque upper limit value. When calculating the torque upper limit value, calculating the allowable torque upper limit value based on the target torque and the rotational speed of the internal combustion engine is a second step. It is an butterfly.

  In this configuration, even if the basic estimated torque is larger than the target torque, it is possible to prevent the torque adjustment parameter from being controlled in the torque decreasing direction when the basic estimated torque is equal to or lower than the allowable torque upper limit value. As a result, it is possible to control the torque adjustment parameters (for example, ignition timing, throttle opening, fuel injection amount, valve timing, etc.) in the torque decreasing direction only when the basic estimated torque becomes slightly larger than the target torque. Since it can prevent, the fall of torque generation efficiency can be suppressed and a fuel consumption can be improved.

In this case, as in 請 Motomeko 1, to lever so as to calculate the allowable maximum torque based on the rotational speed of the target torque and the engine, is possible to change the permissible torque upper limit value according to the target torque In addition, the allowable torque upper limit value can be changed in response to the change in the allowable torque error (the allowable error of the actual torque with respect to the target torque) according to the target torque and the rotational speed of the internal combustion engine. The value can be set to an appropriate value.

Alternatively, as in claim 2 , the present invention is applied to a system including target torque setting means for setting a required torque selected from a plurality of required torques according to various requests of a vehicle as a target torque. Alternatively, the allowable torque upper limit value may be calculated based on the required torque selected as the target torque by the target torque setting means and the allowable torque error corresponding to the required torque. In this way, the target torque and the allowable torque error can be changed according to various demands of the vehicle (for example, the demands of the driver, the demands on the accessories of the internal combustion engine, the demands on the transmission, etc.). Thus, the allowable torque upper limit value can be changed, and the allowable torque upper limit value can be set to an appropriate value.

The present invention, as in claim 3 and 4, by executing a non-ignition retard control to maintain the ignition timing as the torque adjustment parameter to the basic ignition timing when the basic estimated torque is equal to or below the allowable maximum torque It may be prohibited to control the ignition timing in the direction of decreasing the torque, and when the basic estimated torque is larger than the allowable torque upper limit value, ignition retard control that retards the ignition timing from the basic ignition timing may be executed. . In this way, even if the basic estimated torque is greater than the target torque, if the basic estimated torque is less than or equal to the allowable torque upper limit value, the non-ignition retarding control that holds the ignition timing at the basic ignition timing is executed. Thus, it is possible to prevent the ignition timing from being controlled in the torque decreasing direction. On the other hand, when the basic estimated torque is larger than the allowable torque upper limit value, it is possible to control the target torque by reducing the actual torque by executing the ignition delay control that retards the ignition timing from the basic ignition timing. .

  In this case, when the basic estimated torque becomes larger than the allowable torque upper limit value and the non-ignition delay control is switched to the ignition retard control, the ignition timing is changed from the basic ignition timing to the required ignition timing (actual torque is reduced to the target torque). If the ignition timing is retarded stepwise, the actual torque suddenly decreases and becomes discontinuous (a torque step occurs), so uncomfortable torque shock when switching from non-ignition retarded control to ignition retarded control May occur. On the other hand, when the basic estimated torque becomes less than the allowable torque upper limit value and the ignition delay control is switched to the non-ignition delay control, if the ignition timing is advanced stepwise and returned to the basic ignition timing, the actual torque will be Since it suddenly rises and becomes discontinuous, an unpleasant torque shock may occur when switching from ignition retard control to non-ignition retard control.

  As a countermeasure, it is preferable to gradually increase the retard amount of the ignition timing when switching from the non-ignition retard control to the ignition retard control. In this way, when switching from non-ignition retard control to ignition retard control, the retard amount of the ignition timing can be gradually increased, and the ignition timing can be gradually retarded from the basic ignition timing, The actual torque can be reduced gradually. As a result, it is possible to prevent an unpleasant torque shock from occurring when switching from non-ignition retard control to ignition retard control.

  Further, as described in claim 6, when switching from ignition retard control to non-ignition retard control, the retard amount of the ignition timing may be gradually decreased. In this way, when switching from ignition retard control to non-ignition retard control, the retard amount of the ignition timing is gradually decreased, and the ignition timing is gradually advanced to return to the basic ignition timing. The actual torque can be gradually increased. As a result, unpleasant torque shock can be prevented from occurring when switching from ignition retard control to non-ignition retard control.

Further, as described in claim 4 , when switching from ignition retard control to non-ignition retard control, the retard amount of the ignition timing is decreased after the difference between the basic estimated torque and the target torque becomes a predetermined value or less. The ignition timing may be returned to the basic ignition timing. In this way, when switching from the ignition retard control to the non-ignition retard control, the difference between the basic estimated torque and the target torque becomes less than a predetermined value, and the ignition is performed after the target torque approaches the basic estimated torque. Since the ignition timing can be returned to the basic ignition timing by reducing the timing retardation amount, the torque change due to the ignition timing change can be reduced, and switching from ignition retard control to non-ignition retard control The effect of preventing torque shock at the time can be enhanced.

FIG. 1 is a schematic configuration diagram of the entire engine control system in Embodiment 1 of the present invention. FIG. 2 is a block diagram illustrating torque control according to the first embodiment. FIG. 3 is a block diagram for explaining a calculation method (No. 1) of the allowable torque upper limit value. FIG. 4 is a block diagram for explaining a calculation method (No. 2) of the allowable torque upper limit value. FIG. 5 is a block diagram for explaining a calculation method (No. 3) of the allowable torque upper limit value. FIG. 6 is a flowchart illustrating the processing flow of the torque control routine according to the first embodiment. FIG. 7 is a flowchart for explaining the processing flow of the allowable torque calculation routine (part 1). FIG. 8 is a flowchart for explaining the processing flow of the allowable torque calculation routine (part 2). FIG. 9 is a flowchart for explaining the processing flow of the allowable torque calculation routine (part 3). FIG. 10 is a block diagram illustrating torque control according to the second embodiment. FIG. 11 is a flowchart illustrating the processing flow of the torque control routine according to the second embodiment. FIG. 12 is a flowchart for explaining the flow of processing of the allowable torque upper limit equivalent retardation amount calculation routine of the second embodiment. FIG. 13 is a flowchart illustrating the processing flow of the torque control routine according to the third embodiment. FIG. 14 is a time chart illustrating torque control according to the third embodiment. FIG. 15 is a time chart for explaining a problem when switching from non-ignition retard control to ignition retard control. FIG. 16 is a flowchart illustrating the processing flow of the torque control routine according to the fourth embodiment. FIG. 17 is a time chart illustrating torque control according to the fourth embodiment. FIG. 18 is a time chart for explaining a problem when switching from ignition retard control to non-ignition retard control.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

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

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

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

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 27 that detects knocking vibration are 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, and the crank angle and the engine are determined based on the output signal of the crank angle sensor 29. The rotation speed is detected.

  Outputs of these various sensors are input to an engine 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.

At that time, the ECU 30 performs torque control as follows by executing respective torque control routines of FIGS. 6 to 9 described later.
As shown in FIG. 2, first, the target torque is calculated by a map or a mathematical formula based on the accelerator opening, the engine speed, and the like. Based on this target torque, a required intake air amount, a required fuel injection amount, and the like are calculated. Further, an estimated torque (hereinafter referred to as “basic estimated torque”) at the basic ignition timing (for example, the optimal ignition timing MBT at which the generated torque is maximum) is calculated based on the intake air amount, the engine rotation speed, and the like, using a map or a mathematical expression.

  Thereafter, a value obtained by dividing the target torque by the basic estimated torque is calculated as the torque efficiency, and the retard amount of the ignition timing (retard amount from the basic ignition timing) corresponding to the torque efficiency is calculated by a map or a mathematical formula. Thus, the retard amount of the ignition timing for realizing the target torque (hereinafter referred to as “target torque actual retard amount”) is obtained. The target torque realization retardation amount map or mathematical expression is such that the target torque realization retardation amount = 0 when the torque efficiency = 1, and the target torque realization retardation amount increases as the torque efficiency becomes smaller than 1. Is set to

  Further, an allowable torque upper limit value (an upper limit value of an allowable range of actual torque with respect to the target torque) that is larger than the target torque is calculated based on the target torque. Specifically, as shown in FIG. 3, the allowable torque upper limit value is changed according to the target torque by adding a predetermined allowable torque error (for example, 5 Nm) to the target torque to obtain the allowable torque upper limit value.

  Alternatively, as shown in FIG. 4, a permissible torque error (permissible error of the actual torque with respect to the target torque) is calculated based on the target torque and the engine rotational speed by using a map or a mathematical expression, and the permissible torque error is set as the target torque. The allowable torque upper limit value may be obtained by addition. The allowable torque error map or mathematical expression is set such that the allowable torque error increases as the target torque increases, and the allowable torque error increases as the engine speed increases. Thereby, the allowable torque upper limit value can be changed according to the target torque, and the allowable torque upper limit value can be changed in response to the change of the allowable torque error according to the target torque or the engine speed. The allowable torque upper limit value can be set to an appropriate value.

  Further, as shown in FIG. 5, a system that sets a required torque selected from a plurality of required torques according to various requests of the vehicle as a target torque, for example, according to a driver's request (accelerator opening) Calculate the required torque, the required torque according to the request from the accessories of the engine 11 (air conditioner compressor, power steering pump, alternator, etc.), the required torque according to the request from the transmission, etc. In the case of a system in which the smallest required torque among the required torques is set as the target torque, an allowable torque error is calculated for each required torque corresponding to various requests, and the required torque selected as the target torque is calculated. An allowable torque upper limit value may be obtained by adding an allowable torque error corresponding to. As a result, the allowable torque upper limit value can be changed in response to changes in the target torque and the allowable torque error according to various requests of the vehicle, and the allowable torque upper limit value can be set to an appropriate value. it can.

  After the allowable torque upper limit value is set in this way, the basic estimated torque and the allowable torque upper limit value are compared as shown in FIG. As a result, when the basic estimated torque is less than or equal to the allowable torque upper limit value, the non-retard angle determination flag is set to ON and the required retard amount of the ignition timing is set to 0. On the other hand, when the basic estimated torque is larger than the allowable torque upper limit value, the non-retarding angle determination flag is reset to OFF, and the required retard amount of the ignition timing is set to the target torque actual retard amount. Thereafter, a required ignition timing that is retarded by a required retardation amount from the basic ignition timing (for example, the optimal ignition timing MBT) is calculated.

  As a result, when the basic estimated torque is less than or equal to the allowable torque upper limit value, the required retard amount of the ignition timing is set to 0, and non-ignition retard control is performed to hold the ignition timing at the basic ignition timing. It is prohibited to control the timing in the direction of torque reduction. On the other hand, when the basic estimated torque is larger than the allowable torque upper limit value, the ignition retard control is performed to set the required retard amount of the ignition timing to the target torque realization retard amount and retard the ignition timing from the basic ignition timing. By executing, the actual torque is reduced and controlled to the target torque.

Hereinafter, the processing content of each routine for torque control of FIG. 6 thru | or FIG. 9 which ECU30 performs is demonstrated.
The torque control routine shown in FIG. 6 is executed at a predetermined cycle while the ECU 30 is powered on, and serves as torque control means in the claims. When this routine is started, first, at step 101, the target torque is calculated by a map or a mathematical formula based on the accelerator opening, the engine speed, and the like. Based on this target torque, a required intake air amount, a required fuel injection amount, and the like are calculated.

  Thereafter, the process proceeds to step 102, where a basic estimated torque, which is an estimated torque at the basic ignition timing (for example, the optimal ignition timing MBT), is calculated based on the intake air amount, the engine rotation speed, and the like by using a map or a mathematical expression.

  Thereafter, the process proceeds to step 103, and a value obtained by dividing the target torque by the basic estimated torque is calculated as the torque efficiency. Then, the process proceeds to step 104, and the retard amount of the ignition timing according to the torque efficiency (the retard from the basic ignition timing). The target torque realization retardation amount is obtained by calculating the amount) by a map or a mathematical expression.

  In the next step 105, an allowable torque calculation routine of FIG. 7 described later is executed to calculate an allowable torque upper limit value (an upper limit value of the allowable range of actual torque with respect to the target torque) that is larger than the target torque.

  Thereafter, the process proceeds to step 106, and it is determined whether or not the basic estimated torque is equal to or less than the allowable torque upper limit value. As a result, when it is determined that the basic estimated torque is equal to or lower than the allowable torque upper limit value, the routine proceeds to step 107, where the required retard amount of the ignition timing is set to zero.

  On the other hand, if it is determined in step 106 that the basic estimated torque is larger than the allowable torque upper limit value, the process proceeds to step 108, where the required retard amount of the ignition timing is set to the target torque actual retard amount.

  Thereafter, the routine proceeds to step 109, where the basic ignition timing (for example, the optimal ignition timing MBT) is calculated based on the intake air amount, the engine rotational speed, etc. by using a map or a mathematical formula, etc., and then proceeds to step 110, The required ignition timing retarded by the angular amount is calculated.

  By the above processing, when the basic estimated torque is less than or equal to the allowable torque upper limit value, the non-ignition delay control is performed by setting the required retard amount of the ignition timing to 0 and holding the ignition timing at the basic ignition timing. In addition, it is prohibited to control the ignition timing in the torque decreasing direction. On the other hand, when the basic estimated torque is larger than the allowable torque upper limit value, the ignition retard control is performed to set the required retard amount of the ignition timing to the target torque realization retard amount and retard the ignition timing from the basic ignition timing. By executing, the actual torque is reduced and controlled to the target torque.

  The allowable torque calculation routine shown in FIG. 7 is a subroutine executed in step 105 of the torque control routine shown in FIG. 6, and serves as an allowable torque calculation means in the claims. When this routine is started, in step 201, a predetermined allowable torque error (for example, 5 Nm) is added to the target torque to obtain an allowable torque upper limit value.

  Instead of the allowable torque calculation routine shown in FIG. 7, an allowable torque calculation routine shown in FIG. 8 may be executed. In the allowable torque calculation routine shown in FIG. 8, first, in step 301, the allowable torque error (the allowable error of the actual torque with respect to the target torque) is calculated based on the target torque and the engine speed using a map or a mathematical expression. Thereafter, the process proceeds to step 302, where an allowable torque error is added to the target torque to obtain an allowable torque upper limit value.

  Alternatively, instead of the allowable torque calculation routine shown in FIG. 7, an allowable torque calculation routine shown in FIG. 9 may be executed. In the allowable torque calculation routine shown in FIG. 9, first, in step 401, a plurality of required torques according to various requests of the vehicle, for example, required torques according to the driver's request (accelerator opening), and the engine 11 compensation. After calculating the required torque according to the request from the machinery (air conditioner compressor, power steering pump, alternator, etc.), the required torque according to the request from the transmission, etc., proceed to step 402 to meet various requirements An allowable torque error is calculated for each required torque.

  Thereafter, the process proceeds to step 403, where the smallest required torque among a plurality of required torques corresponding to various requests is set as the target torque, and the application ID (identification number) of the requested torque selected as the target torque is stored. .

  Thereafter, the process proceeds to step 404, and an allowable torque error corresponding to the requested torque selected as the target torque is read by reading an allowable torque error corresponding to the stored application ID. Thereafter, the process proceeds to step 405, and an allowable torque upper limit value is obtained by adding an allowable torque error corresponding to the required torque to the required torque selected as the target torque (= target torque).

  In the first embodiment described above, when the basic estimated torque is less than or equal to the allowable torque upper limit value, the ignition timing is reduced in the torque decreasing direction (retarding angle) by executing non-ignition retarding control that holds the ignition timing at the basic ignition timing. Direction), the ignition timing is not controlled in the torque decreasing direction when the basic estimated torque is less than the allowable torque upper limit even if the basic estimated torque is greater than the target torque. can do. As a result, it is possible to prevent the ignition timing from being controlled in the direction of decreasing torque when the basic estimated torque is slightly increased with respect to the target torque. Can be improved.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, the ECU 30 executes the routines shown in FIGS. 11 and 12, which will be described later, so that the ignition timing corresponding to the allowable torque error is obtained based on the target torque and the engine speed as shown in FIG. Is calculated indirectly using a map or a mathematical formula, etc., and then the target torque realization retardation amount is compared with the allowable torque error equivalent retardation amount indirectly. The basic estimated torque is compared with the allowable torque upper limit value.

  As a result, when the target torque actual retardation amount is equal to or less than the allowable torque error equivalent retardation amount, it is determined that the basic estimated torque is equal to or less than the allowable torque upper limit value, and the non-retard angle determination flag is set to ON. Set and set the required retard amount of the ignition timing to zero. On the other hand, when the target torque actual retardation amount is larger than the allowable torque error equivalent retardation amount, it is determined that the basic estimated torque is larger than the allowable torque upper limit value, and the non-retard angle determination flag is turned OFF. Reset to set the required retard amount for the ignition timing to the target torque actual retard amount.

  The routine of FIG. 11 is obtained by changing the processing of steps 105 and 106 of the routine of FIG. 6 described in the first embodiment to the processing of steps 105a and 106a, respectively. Same as 6.

  In the torque control routine shown in FIG. 11, first, a target torque is calculated, a basic estimated torque is calculated, a value obtained by dividing the target torque by the basic estimated torque is calculated as a torque efficiency, and an ignition corresponding to the torque efficiency is calculated. By calculating the retard amount of the timing, the target torque realization retard amount is obtained (steps 101 to 104).

  Thereafter, the process proceeds to step 105a, and an allowable torque error equivalent retardation amount calculation routine shown in FIG. 12 is executed. In this allowable torque error equivalent retardation amount calculation routine, first, in step 501, an allowable torque error equivalent retardation amount (ignition timing retardation amount corresponding to the allowable torque error) is calculated based on the target torque and the engine speed. Calculate by map or mathematical formula.

  Thereafter, the process proceeds to step 106a in FIG. 11 to determine whether or not the target torque realization retardation amount is equal to or less than the allowable torque error equivalent retardation amount, so that the basic estimated torque is indirectly less than or equal to the allowable torque upper limit value. It is determined whether or not there is.

  As a result, when it is determined that the target torque realization retardation amount is equal to or less than the allowable torque error equivalent retardation amount, it is determined that the basic estimated torque is equal to or less than the allowable torque upper limit value, and the routine proceeds to step 107, where ignition is performed. Set the required retardation amount for the time to zero.

  On the other hand, if it is determined in step 106a that the target torque realizing retardation amount is larger than the allowable torque error equivalent retardation amount, it is determined that the basic estimated torque is larger than the allowable torque upper limit value, and step 108 is performed. Then, the required retard amount of the ignition timing is set to the target torque actual retard amount.

  Thereafter, the required ignition timing retarded by the required retard amount from the basic ignition timing (for example, the optimal ignition timing MBT) is calculated (steps 109 and 110). As a result of the above processing, when the basic estimated torque is less than or equal to the allowable torque upper limit value, the ignition timing is controlled in the torque decreasing direction by setting the required retard amount of the ignition timing to 0 and executing non-ignition retard control. Prohibit that. On the other hand, when the basic estimated torque is larger than the allowable torque upper limit value, the required retard amount of the ignition timing is set to the target torque realization retard amount and the ignition retard control is executed, thereby reducing the actual torque and reducing the target torque. Control to torque.

  Also in the second embodiment described above, the same effect as the first embodiment can be obtained.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  As shown in FIG. 15, for example, when the target torque suddenly decreases after gradually decreasing, the basic estimated torque becomes larger than the allowable torque upper limit value, and the non-ignition delay control is switched to the ignition delay control. When the ignition timing is retarded stepwise from the basic ignition timing to the required ignition timing (ignition timing for reducing the actual torque to the target torque), the actual torque suddenly decreases and becomes discontinuous (a torque step occurs) Therefore, an unpleasant torque shock may occur when switching from non-ignition retard control to ignition retard control.

  Therefore, in the third embodiment, by executing a torque control routine of FIG. 13 described later by the ECU 30, the basic estimated torque becomes larger than the allowable torque upper limit value as shown in FIG. When switching from ignition retard control to ignition retard control, the actual torque is gradually decreased by gradually increasing the retard amount of the ignition timing and gradually retarding the ignition timing from the basic ignition timing. . On the other hand, when switching from ignition retard control to non-ignition retard control when the basic estimated torque is less than the allowable torque upper limit, the retard amount of the ignition timing is gradually decreased and the ignition timing is gradually advanced. The actual torque is gradually increased by returning to the basic ignition timing.

  In the torque control routine shown in FIG. 13, first, a target torque is calculated, a basic estimated torque is calculated, a value obtained by dividing the target torque by the basic estimated torque is calculated as a torque efficiency, and an ignition corresponding to the torque efficiency is calculated. By calculating the retard amount of the timing, the target torque realization retard amount is obtained (steps 601 to 604).

  Thereafter, the process proceeds to step 605, where the allowable torque upper limit value is calculated by executing the allowable torque calculation routine of any of the above-described FIGS. It is determined whether or not.

  As a result, if it is determined that the basic estimated torque is larger than the allowable torque upper limit value, the process proceeds to step 608, and the retardation reflection coefficient is increased by a predetermined value (for example, 0.1) from the previous value. However, the upper limit value of the retard angle reflection coefficient is set to 1 to set the upper limit value of the retard angle reflection coefficient to 1. As a result, the retardation reflection coefficient gradually increases from 0 and is finally maintained at 1.

  On the other hand, if it is determined in step 606 that the basic estimated torque is equal to or lower than the allowable torque upper limit value, the process proceeds to step 607, where the retardation reflection coefficient is made smaller by a predetermined value (for example, 0.1) than the previous value. To do. However, the lower limit value of the retard angle reflection coefficient is set to 0 by setting the lower limit guard value of the retard angle reflection coefficient to 0 and performing the guard process. As a result, the retardation reflection coefficient gradually decreases from 1 and is finally maintained at 0.

  Thereafter, the process proceeds to step 609, where the required retardation amount is obtained by multiplying the target torque realization retardation amount by the retardation reflection coefficient. In this case, when the basic estimated torque becomes larger than the allowable torque upper limit value and the non-ignition retardation control is switched to the ignition retardation control, the retardation reflection coefficient gradually increases from 0 and finally becomes 1. Therefore, the required retardation amount gradually increases from 0 and is finally maintained at the target torque actual retardation amount. On the other hand, when the basic estimated torque becomes equal to or lower than the allowable torque upper limit value and the ignition retard control is switched to the non-ignition retard control, the retard reflection coefficient gradually decreases from 1 and is finally maintained at 0. Therefore, the required retardation amount gradually decreases from the target torque achievement retardation amount and is finally maintained at zero.

  Thereafter, the process proceeds to step 610 to calculate a basic ignition timing (for example, the optimum ignition timing MBT), and then proceeds to step 611 to request the required retardation amount from the basic ignition timing (= target torque actual retardation amount × retarding reflection coefficient). The required ignition timing that is retarded by a certain amount is calculated.

  As a result of the above processing, when the basic estimated torque becomes larger than the allowable torque upper limit value and the non-ignition delay control is switched to the ignition delay control, the ignition timing retard amount is gradually increased to increase the ignition timing. By gradually retarding from the basic ignition timing, the actual torque can be gradually reduced. On the other hand, when switching from ignition retard control to non-ignition retard control when the basic estimated torque is less than the allowable torque upper limit, the retard amount of the ignition timing is gradually decreased and the ignition timing is gradually advanced. The actual torque can be gradually increased by returning to the basic ignition timing. As a result, it is possible to prevent an unpleasant torque shock from occurring when switching from non-ignition retard control to ignition retard control or when switching from ignition retard control to non-ignition retard control.

  Next, Embodiment 4 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as in the third embodiment will be omitted or simplified, and different parts from the third embodiment will be mainly described.

  As shown in FIG. 18, for example, when the target torque gradually decreases after suddenly decreasing, the basic estimated torque becomes equal to or lower than the allowable torque upper limit value, and when switching from ignition retard control to non-ignition retard control. In addition, if the ignition timing is advanced stepwise and returned to the basic ignition timing, the actual torque suddenly increases and becomes discontinuous.Therefore, an uncomfortable torque shock occurs when switching from ignition retard control to non-ignition retard control. May occur.

  In the fourth embodiment, therefore, the ECU 30 executes a torque control routine shown in FIG. 16 to be described later, whereby the basic estimated torque becomes equal to or lower than the allowable torque upper limit value as shown in FIG. When switching to ignition retard control, when the difference between the basic estimated torque and the target torque becomes less than the predetermined value and the target torque approaches the basic estimated torque, the retard amount of the ignition timing is decreased to reduce the ignition timing. By returning to the basic ignition timing, the change in torque due to the change in the ignition timing is reduced.

  Note that the routine of FIG. 16 adds the processing of steps 606a and 606b after step 606 of the routine of FIG. 13 described in the third embodiment, and converts the processing of steps 607 and 608 to the processing of steps 607a and 608a, respectively. The processing of the other steps is the same as in FIG.

  In the torque control routine shown in FIG. 16, first, a target torque is calculated, a basic estimated torque is calculated, a value obtained by dividing the target torque by the basic estimated torque is calculated as a torque efficiency, and an ignition corresponding to the torque efficiency is calculated. By calculating the retard amount of the timing, the target torque realization retard amount is obtained (steps 601 to 604).

  Thereafter, the process proceeds to step 605, where the allowable torque upper limit value is calculated by executing the allowable torque calculation routine of any of the above-described FIGS. It is determined whether or not.

  As a result, when it is determined that the basic estimated torque is larger than the allowable torque upper limit value, the process proceeds to step 608a, the non-retard angle determination flag is reset to OFF, and the retard angle reflection coefficient is set to a predetermined value from the previous value. Increase by (for example, 0.1). However, the upper limit value of the retard angle reflection coefficient is set to 1 to set the upper limit value of the retard angle reflection coefficient to 1. As a result, the retardation reflection coefficient gradually increases from 0 and is finally maintained at 1.

  On the other hand, if it is determined in step 606 that the basic estimated torque is equal to or lower than the allowable torque upper limit value, the process proceeds to step 606a, where it is determined whether the non-retard angle determination flag is OFF, and the non-retard angle is determined. If it is determined that the determination flag is OFF, the process proceeds to step 606b, and it is determined whether or not the difference between the basic estimated torque and the target torque is equal to or less than a predetermined value. If it is determined in step 606b that the difference between the basic estimated torque and the target torque is greater than a predetermined value, the process proceeds to step 608a.

  Thereafter, when it is determined in step 606b that the difference between the basic estimated torque and the target torque is equal to or smaller than the predetermined value, the process proceeds to step 607a, the non-retard angle determination flag is set to ON, and the retard angle reflection coefficient is set. Is made smaller than the previous value by a predetermined value (for example, 0.1). However, the lower limit value of the retard angle reflection coefficient is set to 0 by setting the lower limit guard value of the retard angle reflection coefficient to 0 and performing the guard process. As a result, the retardation reflection coefficient gradually decreases from 1 and is finally maintained at 0. If it is determined in step 606a that the non-retard angle determination flag is ON, the process proceeds to step 607a.

  After that, after obtaining the required retard amount by multiplying the target torque actual retard amount by the delay reflection coefficient, the required retard amount (= target torque actual retard amount) from the basic ignition timing (for example, optimum ignition timing MBT). The required ignition timing retarded by (retardation reflection coefficient) is calculated (steps 609 to 611).

  With the above processing, when the basic estimated torque becomes less than the allowable torque upper limit value and the ignition retard control is switched to the non-ignition retard control, the difference between the basic estimated torque and the target torque becomes a predetermined value or less. When the target torque approaches the basic estimated torque, the retard amount of the ignition timing is decreased and the ignition timing is returned to the basic ignition timing, so that the change in torque due to the change in the ignition timing can be reduced. As a result, the effect of preventing torque shock at the time of switching from ignition retard control to non-ignition retard control can be enhanced.

  In each of the first to fourth embodiments, the present invention is applied to a system for controlling the ignition timing so as to realize the target torque based on the basic estimated torque and the target torque. For example, the present invention may be applied to a system that controls the fuel injection amount, the intake air amount (throttle opening), the valve timing, and the like.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 30 ... ECU (torque control means, allowable torque calculation means)

Claims (6)

Torque control of an internal combustion engine provided with torque control means for controlling a torque adjustment parameter based on an estimated torque at the basic ignition timing of the internal combustion engine (hereinafter referred to as “basic estimated torque”) and a target torque In the device
With the allowable torque calculating means for calculating a large permissible torque upper limit value than the target torque, the allowable torque calculation means, the means for calculating the allowable maximum torque based on the rotational speed of the target torque and the engine Have
The torque control device for an internal combustion engine, characterized in that the torque control means has means for prohibiting the torque adjustment parameter from being controlled in a torque decreasing direction when the basic estimated torque is less than or equal to the allowable torque upper limit value. Torque control of an internal combustion engine provided with torque control means for controlling a torque adjustment parameter based on an estimated torque at the basic ignition timing of the internal combustion engine (hereinafter referred to as “basic estimated torque”) and a target torque In the device
Target torque setting means for setting, as the target torque, a request torque selected from a plurality of request torques according to various requests of the vehicle ;
An allowable torque calculating means for calculating an allowable torque upper limit value larger than the target torque based on the target torque,
The allowable torque calculation means have a means for calculating a required torque is selected as the target torque by the target torque setting means, the allowable torque upper limit value on the basis of the allowable torque error corresponding to the required torque,
Said torque control means, the torque control of the internal combustion engine you and a means for inhibiting said basic estimated torque for controlling the torque adjustment parameter in the torque decrease direction when below the permissible torque upper limit value apparatus. The torque control means lowers the ignition timing by executing non-ignition delay control that maintains the ignition timing at the basic ignition timing as the torque adjustment parameter when the basic estimated torque is less than or equal to the allowable torque upper limit value. Means for prohibiting control in the direction, and means for executing ignition delay control for retarding the ignition timing from the basic ignition timing when the basic estimated torque is larger than the allowable torque upper limit value. The torque control device for an internal combustion engine according to claim 1 or 2 , wherein Torque control of an internal combustion engine provided with torque control means for controlling a torque adjustment parameter based on an estimated torque at the basic ignition timing of the internal combustion engine (hereinafter referred to as “basic estimated torque”) and a target torque In the device
An allowable torque calculating means for calculating an allowable torque upper limit value larger than the target torque based on the target torque;
The torque control means lowers the ignition timing by executing non-ignition delay control that maintains the ignition timing at the basic ignition timing as the torque adjustment parameter when the basic estimated torque is less than or equal to the allowable torque upper limit value. Means for prohibiting control in the direction, means for executing ignition delay control for retarding the ignition timing from the basic ignition timing when the basic estimated torque is greater than the allowable torque upper limit value, and the ignition When the retard control is switched to the non-ignition retard control, the ignition timing is reduced to the basic ignition timing by reducing the retard amount of the ignition timing after the difference between the basic estimated torque and the target torque falls below a predetermined value. torque control device of the internal combustion engine you; and a means for returning. 5. The internal combustion engine according to claim 3 , wherein the torque control means includes means for gradually increasing a retard amount of the ignition timing when switching from the non-ignition retard control to the ignition retard control. Engine torque control device. 6. The torque control means according to claim 3, further comprising means for gradually decreasing a retard amount of the ignition timing when switching from the ignition retard control to the non-ignition retard control. A torque control device for an internal combustion engine as described.

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