JP2011094595A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain required torque as required by adequately operating an actuator even when the required torque has a value less than zero. <P>SOLUTION: The instructed opening of a throttle is determined based on the required torque, and estimated MBT torque for operating the throttle is calculated in accordance with the instructed opening. Then, a value for the required torque is corrected to a relative value to reference torque set to a value less than zero, and a value for the estimated MBT torque is also corrected to a relative value to the reference torque. Then, the rate of the required torque after corrected to the estimated MBT torque after corrected is calculated as torque efficiency, and a delay in an ignition timing required to actualize the required toque is determined based on the torque efficiency. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

    The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for an internal combustion engine that obtains a required value of torque to be output to the internal combustion engine (hereinafter referred to as required torque) and cooperatively operates a plurality of actuators according to the required torque.

  As a method for controlling the torque of an internal combustion engine for a vehicle, so-called torque demand control is known in which a plurality of actuators are cooperatively operated according to required torque. Japanese Patent Application Laid-Open No. 2009-174328 (Patent Document 1), Japanese Patent Application Laid-Open No. 2009-167916 (Patent Document 2) or Japanese Patent Application Laid-Open No. 2009-068430 (Patent Document 3) shows an example of such torque demand control. Are listed.

  The control devices described in the above patent documents (hereinafter referred to as conventional control devices) control the torque of the internal combustion engine based on the throttle opening and the ignition timing. Specifically, the conventional control device determines the command opening for the throttle based on the required torque. Then, the estimated MBT torque (estimated torque when the ignition timing is assumed to be MBT) when the throttle is operated according to the command opening is calculated, and the ratio of the required torque to the estimated MBT torque is calculated as the torque efficiency. The estimated MBT torque is the maximum torque that the internal combustion engine can potentially output under the command opening, and the torque efficiency is required to be actually output with respect to the torque that the internal combustion engine can potentially output. It means the percentage of torque that is being used. Therefore, the maximum value of torque efficiency is 1, and the smaller the torque efficiency is, the more actuator operation is required to reduce the torque. The conventional control device controls the torque output from the internal combustion engine as required by determining the retardation amount from the MBT of the ignition timing based on the torque efficiency.

JP 2009-174328 A JP 2009-167916 A JP 2009-068430 A

  By the way, the torque output from the internal combustion engine may be a negative value. FIG. 6 is a PV diagram of a four-cycle internal combustion engine. As shown in this figure, the internal combustion engine generates torque by combustion in the compression to expansion stroke, but consumes torque due to pump loss in the exhaust to intake stroke. The indicated torque of the internal combustion engine is the sum of the positive generated torque and the negative pump loss torque. Therefore, if the generated torque due to combustion is smaller than the pump loss torque, the torque output from the internal combustion engine becomes a negative value.

  FIG. 7 shows a range of torque that can be controlled by retarding the ignition timing in the internal combustion engine. However, the possibility of misfire is not considered here. As shown in this figure, if the pump loss torque is used, even if a torque value smaller than zero is required, the required torque can be realized by appropriately operating each actuator. Is possible. If the required torque can be reduced to a negative value, the torque generated by combustion can be reduced as much as possible. For example, if this is performed before the deceleration fuel cut, the torque shock associated with the fuel cut is minimized. Can be suppressed.

  However, there are the following problems when a torque range of zero or less is used in torque control of an internal combustion engine.

  As the required torque is lowered, the throttle is closed accordingly. As a result, when the required torque is reduced to a value of zero or less, the estimated MBT torque calculated based on the command opening to the throttle may follow the required torque and become a value of zero or less. At that time, since the torque efficiency is a ratio of the required torque to the estimated MBT torque, when the estimated MBT torque value becomes zero, a zero percent error occurs in the calculation of the torque efficiency. Furthermore, even if the zero percent is avoided by some method, the denominator changes from a positive value to a negative value, and the continuity of the torque efficiency value is lost.

  Such a problem occurs because the conventional torque efficiency calculation method is based on the premise that the required torque is larger than zero and the torque efficiency is in the range from zero to one. For this reason, even if a torque of a value smaller than zero is required in the conventional control device, the correspondence relationship between the torque efficiency and the retard amount of the ignition timing is broken, so that the retard required for realizing the requested torque is lost. The amount cannot be determined based on torque efficiency.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to appropriately operate an actuator so that the required torque can be realized as required even when the required torque is a value of zero or less. .

In order to achieve the above object, a control device for an internal combustion engine according to a first invention comprises:
Applied to an internal combustion engine having a main actuator that adjusts the intake air amount as an actuator for controlling torque and a subactuator that adjusts engine parameters other than the intake air amount, and a required torque value to be output to the internal combustion engine ( Hereinafter, in the control device for operating the main actuator and the sub-actuator according to the required torque)
Main actuator operation amount determination means for determining an operation amount of the main actuator based on the required torque;
Estimated latent torque calculating means for calculating an estimated latent torque of the internal combustion engine based on an operation amount of the main actuator;
Request torque correction means for correcting the value of the request torque to a relative value with respect to a reference torque set to a value smaller than zero;
Estimated latent torque correction means for correcting the value of the estimated latent torque to a relative value with respect to the reference torque;
Torque efficiency calculating means for calculating a ratio of the required torque after correction to the estimated latent torque after correction (hereinafter, torque efficiency);
Sub-actuator operation amount determining means for determining an operation amount of the sub-actuator necessary for realizing the required torque based on the torque efficiency;
It is characterized by having.

A control device for an internal combustion engine according to a second invention is the control device for an internal combustion engine according to the first invention,
The reference torque is set according to the maximum pump loss torque that is assumed.

A control device for an internal combustion engine according to a third invention is the control device for an internal combustion engine according to the first invention,
The reference torque is changed according to the operating condition of the internal combustion engine so as to correspond to the pump loss torque generated under the current operating condition,
The sub-actuator operation amount determining means corrects the correspondence relationship between the torque efficiency and the operation amount of the sub-actuator according to the change of the reference torque.

  According to the control apparatus for an internal combustion engine of the first invention, when calculating the torque efficiency, the required torque is increased by the amount of the reference torque, and the estimated latent torque is also increased by the amount of the reference torque. Then, torque efficiency is calculated using the raised required torque and estimated latent torque. By calculating the torque efficiency in this way, the torque efficiency value can be kept above zero even when the required torque is a value below zero, and the difference between the required torque and the estimated potential torque Accordingly, it is possible to obtain torque efficiency that varies linearly in the range from 1 to zero as the maximum value. Therefore, according to the control apparatus for an internal combustion engine of the first invention, it is possible to make the torque efficiency value correspond to the operation amount of the sub-actuator, and even if the required torque is a value of zero or less The required torque can be realized as required by operating each actuator.

  According to the control apparatus for an internal combustion engine of the second invention, since the reference torque is set in accordance with the assumed maximum pump loss torque, until the torque generated by combustion becomes zero, that is, to the minimum value. The required torque can be reduced. Further, if the torque efficiency numerator and the denominator are increased, the value as information on the deviation between the required torque and the estimated potential torque is diluted. However, by setting the reference torque as described above, the torque efficiency The value of the torque efficiency as the above information can be sufficiently secured while eliminating the possibility that the torque efficiency becomes smaller than zero.

  According to the control device for an internal combustion engine of the third aspect of the invention, the reference torque is changed in accordance with the pump loss torque that changes according to the operating conditions. Optimum accuracy can be ensured while eliminating. Also, when the reference torque is changed, the correspondence between torque efficiency and the amount of operation of the sub-actuator is also corrected accordingly, so that even if the reference torque is changed, each actuator is appropriately operated and requested. Torque can be achieved as required.

It is a block diagram which shows the structure of the control apparatus of the internal combustion engine of Embodiment 1 of this invention. It is a figure for demonstrating the calculation method of the torque efficiency implemented in Embodiment 1 of this invention. It is a block diagram which shows the structure of the control apparatus of the internal combustion engine of Embodiment 2 of this invention. It is a figure for demonstrating the calculation method of the torque efficiency implemented in Embodiment 2 of this invention. It is a flowchart which shows the procedure of the calculation of the torque efficiency implemented in Embodiment 2 of this invention. It is a PV diagram of a 4-cycle internal combustion engine. It is a figure for demonstrating the problem of the calculation method of the conventional torque efficiency.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS.

  FIG. 1 is a block diagram showing a configuration of a control device for an internal combustion engine according to the present embodiment. The internal combustion engine to be controlled in the present embodiment is a spark ignition type four-cycle reciprocating engine. The control device controls the operation of the internal combustion engine by operating an actuator provided in the internal combustion engine. The actuator that can be operated by the control device includes an ignition device, a throttle, a fuel injection device, a variable valve timing mechanism, an EGR device, and the like. However, in this embodiment, the control device operates the throttle and the ignition device, and the control device operates these two actuators to control the torque output from the internal combustion engine. The operation amount of the throttle by the control device is the throttle opening (hereinafter also referred to as TA), and the operation amount of the ignition device is the ignition timing (hereinafter also referred to as SA). The control device outputs a command value of each manipulated variable to the internal combustion engine, that is, a command opening (TA) and a command ignition timing (SA).

  As shown in FIG. 1, the control device of the present embodiment acquires the required torque and the required efficiency. In the vehicle control system, a power train manager (not shown) is arranged above the control device of the present embodiment, and the required torque and the required efficiency are input from the power train manager to the control device. ing. The required torque is a torque to be output to the internal combustion engine, more strictly, a required value of the indicated torque. Efficiency is the ratio of the torque that is actually output to the potential torque that the internal combustion engine can output, and the required efficiency is the required value. The maximum value of the efficiency is 1, and at that time, the potential torque that can be output by the internal combustion engine is actually output as it is. When the efficiency is less than 1, the torque that is actually output is smaller than the potential torque that can be output by the internal combustion engine, and the margin is mainly output as heat and output from the internal combustion engine. Therefore, for example, when it is desired to increase the exhaust temperature positively, such as when the catalyst is warmed up, the actuator operation may be performed so that the efficiency is less than 1.

  The control device of the present embodiment inputs the acquired required torque and required efficiency to the divider 2 and divides the required torque by the required efficiency. A value obtained by dividing the required torque by the required efficiency is used as torque for throttle opening calculation. When the required efficiency is smaller than 1, the torque for calculating the throttle opening is raised more than the required torque. This means that the throttle is required to be able to potentially output a torque larger than the required torque.

  The throttle opening calculation unit 4 converts the input throttle opening calculation torque value into a cylinder air amount (or charging efficiency) value, and further converts it into an instruction opening (TA) to the throttle. A torque-air amount conversion map is used to convert the throttle opening calculation torque into the in-cylinder air amount. In the torque-air amount conversion map, assuming that the ignition timing is MBT, the torque and the air amount are associated using various engine information as keys. An inverse model of the air model is used to convert the in-cylinder air amount into the indicated opening. The air model is a physical model of the intake system that models the response of the in-cylinder air amount to the operation of the throttle. The throttle opening calculated by the inverse model is the throttle opening required to achieve the required in-cylinder air amount, and the control device outputs the throttle opening as an instruction opening to the throttle.

  In the control device of the present embodiment, in parallel with the above processing, the estimated MBT torque calculation unit 6 calculates the estimated MBT torque based on the actual throttle opening. The estimated MBT torque is a torque that can be output when the ignition timing is set to MBT based on the current throttle opening, that is, an estimated value of the torque that the internal combustion engine can potentially output. This estimated MBT torque is input to the divider 8 together with the required torque, and the ratio of the required torque to the estimated MBT torque is calculated as the torque efficiency.

  However, in the present embodiment, the required torque used for calculating the torque efficiency is corrected by the required torque correction unit 12. Similarly, the estimated MBT torque used for calculating the torque efficiency is corrected by the estimated MBT torque correction unit 14. As shown in the figure, the required torque correction unit 12 adds the reference torque with a minus sign to the required torque. In the estimated MBT torque correction unit 14, the reference torque is added to the estimated MBT torque with a minus sign. By these additions, the required torque and the estimated MBT torque are each corrected from a relative value with respect to zero to a relative value with respect to the reference torque.

The reference torque is a predetermined fixed value smaller than zero. For this reason, when calculating the torque efficiency, the required torque is increased by the amount of the reference torque, and the estimated MBT torque is also increased by the amount of the reference torque. FIG. 2 illustrates this point. The axis in FIG. 2 is the indicated torque, Tt indicates the magnitude of the required torque as the indicated torque, and Te indicates the magnitude of the estimated MBT torque as the indicated torque. Tt _offset is the required torque after correction, the length of the arrow line indicates the magnitude of the absolute value of the corrected required torque, and the direction of the arrow line indicates whether it is a positive value or a negative value. Te _offset is the estimated MBT torque after correction, the length of the arrow line indicates the absolute value of the corrected estimated MBT torque, and the direction of the arrow line indicates whether it is a positive value or a negative value.

As can be seen from FIG. 2, even if the required torque (Tt) is a value less than or equal to zero, if the reference torque is a negative value larger than the required torque (Tt), the corrected required torque (Tt _offset) ) Is a value greater than or equal to zero. Similarly, the post-correction estimated MBT torque (Te _offset ) becomes a value of zero or more. Therefore, the value of the torque efficiency is a ratio of the corrected required torque _{(Tt offset)} relative to the corrected estimated MBT torque _{(Te offset)} will be maintained above zero. Further, by calculating the torque efficiency in this way, a torque efficiency that linearly changes in a range from 1 to zero of the maximum value according to the difference between the required torque (Tt) and the estimated MBT torque (Te) is obtained. be able to.

  The ignition timing calculation unit 10 determines an ignition timing (SA) necessary for realizing the required torque based on the torque efficiency calculated by the divider 8. In the determination of the ignition timing, if the torque efficiency is 1, the retard amount from the MBT of the ignition timing is set to zero, and the retard amount from the MBT of the ignition timing is increased as the torque efficiency is smaller than 1. According to the control device of the present embodiment, the torque efficiency is maintained in the range from the maximum value of 1 to zero, and therefore it is possible to make the torque efficiency value correspond to the retard amount of the ignition timing. Even when the required torque is a value equal to or less than zero, it is possible to appropriately set the ignition timing and achieve the required torque as required.

  Note that if the reference torque value is set to a very large negative value, the accuracy of torque control by retarding the ignition timing may be reduced. This is because torque efficiency has the meaning of information on the difference between the required torque and the estimated MBT torque, but as the ratio of the raised portion (reference torque) in the numerator and denominator of torque efficiency increases, This is because the value is diluted.

  On the other hand, if the value of the reference torque is too close to zero, there is a possibility that the required torque will be lower than the reference torque when the required torque becomes a value of zero or less. In that case, the torque efficiency becomes a value smaller than zero. In addition, the value of the denominator becomes zero, and a zero percent error may occur.

  Considering the above points, it is preferable that the reference torque value is set in accordance with the assumed maximum pump loss torque. By doing so, the required torque can be reduced to the minimum value until the torque generated by combustion becomes zero, that is, the possibility that the torque efficiency becomes smaller than 0 or a zero percent error occurs is eliminated. However, sufficient accuracy of torque control by retarding the ignition timing can be ensured.

Embodiment 2. FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 3, 4 and 5. FIG.

  FIG. 3 is a block diagram showing the configuration of the control device for the internal combustion engine of the present embodiment. One of the features of the control device of the present embodiment is that the reference torque is a pump loss torque generated under the current operating conditions. The pump loss torque varies depending on operating conditions such as throttle opening, engine speed, valve timing, EGR rate, and the like. The control device of the present embodiment has a map that associates the operating conditions of the internal combustion engine with the pump loss torque, and calculates the pump loss torque according to the operating conditions with reference to the map. The calculation is performed in the pump loss torque calculator 16.

In the required torque correction unit 12, the pump loss torque is added to the required torque with a minus sign. Further, in the estimated MBT torque correcting unit 14, the pump loss torque is added to the estimated MBT torque with a minus sign. Then, the torque efficiency is calculated using the required torque raised by the pump loss torque and the estimated MBT torque. FIG. 4 illustrates this point, and FIG. 5 shows a series of calculation procedures in a flowchart. The meanings of Tt, Te, Tt _offset, and Te _offset in FIG. 4 are the same as those in FIG. Tp is the pump loss torque, the length of the arrow line indicates the magnitude of the absolute value of the pump loss torque, and the direction of the arrow line indicates a positive value or a negative value.

As shown in the flowchart of FIG. 5, the control device according to the present embodiment acquires the required torque (Tt) in the first step S2. In the next step S4, the estimated MBT torque calculation unit 6 calculates an estimated MBT torque (Te). Next or in parallel, in step S6, the pump loss torque calculation unit 16 calculates the pump loss torque (Tp). In the next step S8, the torques offset by the pump loss torque (Tp), that is, the corrected required torque (Tt _offset ) and the corrected estimated MBT torque (Te _offset ) are calculated. In the last step S10, the torque efficiency is calculated by dividing the corrected required torque (Tt _offset ) by the corrected estimated MBT torque (Te _offset ).

  As described above, in the control device of the present embodiment, the reference torque is changed in accordance with the pump loss torque (Tp) that changes according to the operating condition of the internal combustion engine. According to this, while eliminating the possibility that the torque efficiency will be smaller than 0 or cause a zero percent error in the entire operation region of the internal combustion engine, the ratio of the raised portion (reference torque) in the numerator and denominator of the torque efficiency is reduced. It can be minimized.

  The ignition timing calculation unit 10 determines an ignition timing (SA) necessary for realizing the required torque based on the torque efficiency calculated by the above method. The control device according to the present embodiment is also characterized by the ignition timing determination method in the ignition timing calculation unit 10. As shown in FIG. 3, in this embodiment, the pump loss torque calculated by the pump loss torque calculation unit 16 is also input to the ignition timing calculation unit 10. The ignition timing calculation unit 10 corrects the correspondence relationship between the torque efficiency and the retard amount of the ignition timing according to the input pump loss torque. This is because even if the estimated MBT torque and the required torque are both constant, if the value of the pump loss torque is changed according to the operating conditions, the value of the torque efficiency also changes accordingly. is there. One or a plurality of maps are used in the process of determining the correction amount of the ignition timing from the torque efficiency, and one of the maps is created with the pump loss torque as one of the arguments.

  As described above, according to the control device of the present embodiment, even if the calculated value of the pump loss torque changes due to a change in the operating condition, the correspondence relationship between the torque efficiency and the retard amount of the ignition timing accordingly. It is corrected. As a result, it is possible to appropriately retard the ignition timing in the entire operation region of the internal combustion engine and achieve the required torque as required.

  Note that there is a delay of one or several clocks between the correction of the required torque and the estimated MBT torque until the ignition timing is calculated by the ignition timing calculation unit 10, and the calculated value of the pump loss torque changes during that time. There is a case. Therefore, it is preferable to delay the input of the pump loss torque to the ignition timing calculation unit 10 by the delay. By doing so, the value of the pump loss torque used as an argument of the map can be made equal to the value used for correcting the required torque and the estimated MBT torque.

Others.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above-described embodiment, the throttle opening calculation torque is obtained by obtaining the required torque and the required efficiency and dividing the required torque by the required efficiency. However, the required efficiency is not always necessary. For example, when the operation is required so that the efficiency always becomes the maximum value 1, the divider 2 may be deleted and the required torque may be used as it is as the throttle opening calculation torque.

  In the above-described embodiment, the torque is controlled using the throttle opening and the ignition timing as the operation amount, but the combination of the operation amounts is not limited to this. A combination of an operation amount relating to an actuator (main actuator) for adjusting the intake air amount and an operation amount relating to an actuator (sub-actuator) for adjusting a parameter other than the intake air amount may be used. Then, the operation amount of the sub actuator may be determined based on the torque efficiency. In addition, as a subactuator, the thing with the responsiveness of the torque with respect to the change of the manipulated variable is superior to that of the main actuator. The ignition device used in the above-described embodiment is an example of such a sub-actuator.

2 Divider (Required latent torque calculation means)
4 Throttle opening calculation unit (main actuator operation amount determination means)
6 Estimated MBT torque calculation unit (estimated latent torque calculation means)
8 Divider (torque efficiency calculation means)
10 Ignition timing calculation unit (sub-actuator operation amount determination means)
12 Required torque correction part (Requested torque correction means)
14 Estimated MBT torque correction unit (estimated latent torque correction means)
16 Pump loss torque calculator

Claims (3)

Applied to an internal combustion engine having a main actuator that adjusts the intake air amount as an actuator for controlling torque and a subactuator that adjusts engine parameters other than the intake air amount, and a required torque value to be output to the internal combustion engine ( Hereinafter, in the control device for operating the main actuator and the sub-actuator according to the required torque)
Main actuator operation amount determination means for determining an operation amount of the main actuator based on the required torque;
Estimated latent torque calculating means for calculating an estimated latent torque of the internal combustion engine based on an operation amount of the main actuator;
Request torque correction means for correcting the value of the request torque to a relative value with respect to a reference torque set to a value smaller than zero;
Estimated latent torque correction means for correcting the value of the estimated latent torque to a relative value with respect to the reference torque;
Torque efficiency calculating means for calculating a ratio of the required torque after correction to the estimated latent torque after correction (hereinafter, torque efficiency);
Sub-actuator operation amount determining means for determining an operation amount of the sub-actuator necessary for realizing the required torque based on the torque efficiency;
A control device for an internal combustion engine, comprising:   2. The control apparatus for an internal combustion engine according to claim 1, wherein the reference torque is set in accordance with a maximum pump loss torque assumed. The reference torque is changed according to the operating condition of the internal combustion engine so as to correspond to the pump loss torque generated under the current operating condition,
2. The control apparatus for an internal combustion engine according to claim 1, wherein the sub-actuator operation amount determination means corrects the correspondence relationship between the torque efficiency and the operation amount of the sub-actuator according to the change of the reference torque.

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