JP2011185122A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a torque difference that arises if a request to increase torque continuously from an idle state is outputted, regarding a control device for an internal combustion engine whose operation is controlled by throttle opening and ignition timing. <P>SOLUTION: The torque required and the efficiency required are obtained and the potential torque required is calculated by dividing the torque required by the efficiency required. The required amount of cylinder air needed to achieve the potential torque required is calculated and an opening command value for a throttle is determined based on it. Estimated potential torque when the throttle is operated in accordance with the opening command value is calculated and the ratio (estimated efficiency) of the torque required to it is calculated. In this case, if the value of the efficiency required is less than one and if a certain request to increase torque is issued during idle operation, an annealing process for slowing the rate of change of the torque required is performed on the required torque used in the calculation of the estimated efficiency. With the estimated efficiency serving as the efficiency instructed, the delay amount of ignition timing is determined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device, and more particularly to an internal combustion engine control device whose operation is controlled by the opening of a throttle and ignition timing.

  As a method for controlling the torque of the internal combustion engine, so-called torque demand control is known in which the throttle opening and the ignition timing are cooperatively controlled based on the required torque. The technique disclosed in Japanese Patent Laid-Open No. 2006-138300 also relates to such torque demand control. In the technique disclosed in this publication, a torque margin value for torque reservation is input separately from the required torque, and the throttle opening and ignition timing are calculated based on the required torque and the torque margin value. Specifically, the throttle opening is calculated from a value obtained by adding a torque margin value to the required torque. Further, the retard amount of the ignition timing is calculated from the ratio between the required torque and a value obtained by adding a torque margin value to the required torque.

JP 2006-138300 A

  A problem arises in the prior art when there is a continuous torque increase request during idle operation of the internal combustion engine. That is, in the idle state, the throttle valve is operated to achieve the ISC target MBT torque (in other words, the value obtained by adding the torque margin value to the ISC required torque), and the required torque is reduced by retarding the ignition timing. Realized. Here, when the accelerator pedal is depressed from the idle state, the required torque increases in accordance with the amount of depression of the accelerator, and the in-cylinder air amount required increases accordingly. However, the actual in-cylinder air amount changes with a delay from the required in-cylinder air amount due to the influence of air in the surge tank. For this reason, the actual in-cylinder air amount during the change of the required torque becomes a state where the air becomes transiently insufficient.

  Here, as in the above-described prior art, when a torque margin value remains, the required torque can be realized by advancing the ignition timing to compensate for the shortage of air in the cylinder. However, it is during the period until the ignition timing reaches MBT that the torque can be compensated by the retard of the ignition timing. For this reason, subsequent increases in the required torque can be handled only by the response of the actual in-cylinder air amount.

  FIG. 3 is a chart showing the movement of the torque, the in-cylinder air amount, and the ignition timing as described above along the time axis. According to the prior art, the ignition timing is advanced as the required torque increases, and the advance of the ignition timing acts in the direction of increasing the torque. The ignition timing reaches MBT when the value of the required torque reaches the value of the target MBT torque of ISC. However, since the actual in-cylinder air amount has not yet responded at this time, a step is generated in the actually realized torque. As apparent from FIG. 3, the conventional technique has a problem that a torque step occurs when a continuous torque increase request from the idle state is issued.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine that can alleviate a torque step generated when a continuous torque increase request is issued from an idle state. The purpose is to provide.

In order to achieve the above object, a first invention provides a control device for an internal combustion engine capable of controlling torque by the throttle opening and ignition timing.
Requested torque acquisition means for acquiring a required value of torque to be output to the internal combustion engine (hereinafter referred to as required torque);
Requested efficiency acquisition means for acquiring a required value (hereinafter referred to as required efficiency) of the ratio of the actually output torque to the potential torque that can be output by the internal combustion engine;
Required latent torque calculating means for calculating required latent torque by dividing the required torque by the required efficiency;
A required in-cylinder air amount calculating means for calculating an in-cylinder air amount (hereinafter referred to as a required in-cylinder air amount) necessary for realizing the required latent torque;
An opening command value determining means for determining an opening command value for the throttle based on the required in-cylinder air amount;
Estimated latent torque calculating means for calculating an estimated latent torque when the throttle is operated according to the opening command value;
Estimated efficiency calculating means for calculating a ratio of the required torque to the estimated latent torque (hereinafter, estimated efficiency);
When the required efficiency value is less than 1 and when a predetermined torque increase request is issued during idle operation of the internal combustion engine, the required torque used for calculating the estimated efficiency is An annealing process means for performing an annealing process to slow down the rate of change,
Ignition timing retard amount determining means for determining the retard amount of the ignition timing using the estimated efficiency as the instruction efficiency;
It is characterized by providing.

According to a second invention, in the first invention,
The annealing processing means includes means for setting a processing degree of the annealing process, and the processing degree is set higher as the change rate of the required torque is larger.

According to a third invention, in the first or second invention,
The annealing processing means includes means for setting the processing degree of the annealing process, and the processing degree is set lower as the engine speed of the internal combustion engine is larger.

A fourth invention is any one of the first to third inventions,
The annealing processing means includes means for subjecting the required torque used for calculation of the estimated efficiency to a predetermined filter process for slowing the rate of change of the required torque, and changing a time constant of the filter process. The degree of processing of the annealing process is set in (1).

  According to the control apparatus for an internal combustion engine of the first aspect of the present invention, the estimated efficiency is calculated when the latent torque is larger than the actually output torque and when a predetermined torque increase request is issued during idle operation. An annealing process is performed on the required torque used in the above-described process so as to slow down the rate of change of the required torque. As a result, the rate of change in the estimated efficiency calculated using the required torque that has been subjected to the annealing process also becomes slow, and thus the rate of advance of the ignition timing also becomes slow. For this reason, according to the present invention, it is possible to lengthen the required torque realization time due to the advance of the ignition timing, and therefore it is possible to effectively relieve the torque step generated due to the response delay of the cylinder air amount.

  According to the control apparatus for an internal combustion engine of the second invention, in the required torque smoothing process used to calculate the estimated efficiency, the processing degree of the smoothing process is set higher as the required torque change rate is larger. The greater the change rate of the required torque, the shorter the time required for realizing the required torque due to the advance of the ignition timing, and the greater the torque step generated. For this reason, according to the present invention, the greater the change rate of the required torque, the slower the rate of ignition timing advancement, and thus the torque step can be effectively reduced.

  According to the control apparatus for an internal combustion engine of the third invention, in the required torque smoothing process used to calculate the estimated efficiency, the processing degree of the smoothing process is set lower as the engine speed of the internal combustion engine is larger. The greater the engine speed, the smaller the delay in response of the in-cylinder air amount, so the generated torque step is alleviated. For this reason, according to the present invention, the larger the engine speed, the more quickly the rate of ignition timing advancement. Therefore, both the reduction of the torque step and the improved response of the output torque can be achieved. Is possible.

  According to the control apparatus for an internal combustion engine of the fourth aspect of the invention, when a predetermined filter process is performed as the required torque smoothing process used to calculate the estimated efficiency, the processing degree of the smoothing process is changed by changing the time constant. Is adjusted. Therefore, according to the present invention, it is possible to perform a desired degree of annealing on the required torque by a simple method.

It is a block diagram which shows schematic structure of the control system of the internal combustion engine to which this invention is applied. It is a figure for demonstrating the torque control concerning Embodiment 1 of this invention. It is a figure for demonstrating the problem of a prior art.

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

  The internal combustion engine to be controlled in the first embodiment of the present invention 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. In the embodiment of the present invention, the control device operates a throttle and an 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, an opening command value (TA) and an ignition timing command value (SA).

  FIG. 1 is a block diagram showing a configuration of a control device for an internal combustion engine according to Embodiment 1 of the present invention. 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 input required torque includes the required torque from various control devices such as ISC, VSC, or TRC in addition to the driver required torque calculated from the opening of the accelerator pedal because of the necessity for vehicle control.

  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.

  The control device of the present embodiment inputs the acquired required torque and required efficiency to the target MBT torque calculation unit 2. The target MBT torque calculation unit 2 obtains the target MBT torque by dividing the required torque by the required efficiency. The target MBT torque is a target value of the output torque on the assumption that the ignition timing is MBT, and is the above-described required value of the latent torque, that is, the required potential torque.

  The target MBT torque is converted into a cylinder air amount (or charging efficiency) value in the cylinder air amount calculation unit 4. The in-cylinder air amount calculation unit 4 uses an air amount map for converting torque into in-cylinder air amount. The air amount map is a map in which the torque and the in-cylinder air amount are associated using various engine information as a key on the assumption that the ignition timing is MBT. Here, the in-cylinder air amount necessary for realizing the target MBT torque that is the required latent torque, that is, the required in-cylinder air amount is calculated.

  Next, in the throttle opening calculation unit 6, the required in-cylinder air amount is converted into an opening command value (TA) for the throttle. An inverse model of the air model (air inverse model) is used for the conversion. The air model is a physical model of the intake system in which the response of the in-cylinder air amount to the operation of the throttle is modeled based on fluid dynamics. The throttle opening calculated by the inverse model is a throttle opening required to achieve the required in-cylinder air amount, and the control device outputs the throttle opening as an opening command value to the throttle.

  In parallel with the above processing, the control device according to the present embodiment calculates the estimated MBT torque based on the actual throttle opening (actual TA) in the estimated MBT torque calculator 8. The estimated MBT torque is an estimated torque when the ignition timing is assumed to be MBT, and this means a torque (estimated latent torque) that the internal combustion engine can potentially output under the current throttle opening. A torque map is used to calculate the estimated MBT torque. The torque map is obtained by reversing the input / output of the air amount map described above, and the torque and the air amount are associated with various engine information as a key on the assumption that the ignition timing is MBT.

  The estimated MBT torque is input to the torque efficiency calculation unit 10 together with the required torque. The torque efficiency calculation unit 10 calculates the ratio of the required torque to the estimated MBT torque as the torque efficiency. The torque efficiency is an estimated efficiency when the ignition device is operated so as to achieve the required torque under the current throttle opening.

  The control device according to the present embodiment duplicates the request torque signal and inputs the duplicated request torque to the smoothing processing unit 12. The annealing processing unit 12 performs a low-pass filter process on the input required torque to slow down the change in the required torque. The degree of the annealing process is adjusted by changing the time constant of the low-pass filter. More specifically, the greater the rate of change in the input required torque, the smaller the time constant and the greater the degree of smoothing processing. In addition, as the engine speed of the internal combustion engine increases, the time constant is increased to reduce the degree of the annealing process. The annealed required torque is input to the changeover switch 14 together with the original required torque.

  The changeover switch 14 selects and outputs only one of the two types of input requested torque. However, the default of the selection is the original required torque, and the selection is switched from the original required torque to the required torque subjected to the delay process only when a switching signal is input from the transient region determination unit 16 to the changeover switch 14. .

  The transient region determination unit 16 outputs a switching signal to the changeover switch 14 when a continuous torque increase request from the idle state is issued, that is, when the accelerator pedal is depressed in the idle state. Therefore, when this condition is satisfied, the changeover switch 14 outputs the required torque that has been subjected to the smoothing process instead of the original required torque.

  The required torque selected by the changeover switch 14 is input to the torque efficiency calculation unit 10 together with the estimated MBT torque. The ratio of the required torque to the estimated MBT torque is calculated as torque efficiency. The control device according to the present embodiment uses the torque efficiency as it is as the instruction efficiency, and the ignition timing calculation unit 18 converts the instruction efficiency into an ignition timing command value (SA).

  By adopting the configuration described above, the control device of the present embodiment has the following advantages.

  FIG. 2 is a chart showing the movement of the torque, the in-cylinder air amount, and the ignition timing along the time axis when a request for continuously increasing the required torque is issued during ISC control. More specifically, in the chart shown in FIG. 2, the required torque input to the control device, the required torque subjected to the annealing process, the estimated MBT torque calculated in the control device, and the output from the internal combustion engine. The relationship with the output torque is shown.

  In the ISC control during idle operation, the required torque of ISC is acquired as the required torque, and the value of the required efficiency is less than 1. As a result, the target MBT torque realized by operating the throttle is controlled to the ISC target MBT torque shown in the figure, and the ISC required torque is realized by retarding the ignition timing from the MBT. The Here, as shown in FIG. 2, when a request for increasing the required torque is issued, the control device of the present embodiment calculates the torque efficiency using the required torque subjected to the annealing process. For this reason, according to the retard amount of the ignition timing calculated based on the torque efficiency, the output torque is controlled to coincide with the required torque subjected to the annealing process. Thereby, since the time required for the advance of the ignition timing can be prolonged, the torque step caused by the response delay of the air amount can be effectively reduced.

  Also, the control device of the present embodiment increases the degree of the smoothing process by decreasing the time constant of the low-pass filter as the change rate of the required torque increases in the smoothing process of the input requested torque. The larger the change rate of the required torque, the shorter the time required to advance the ignition timing to MBT, so the torque step becomes larger. Therefore, the torque step can be effectively reduced by increasing the degree of the smoothing process when the change rate of the required torque is large.

  Further, in the smoothing process of the input requested torque, the control device of the present embodiment decreases the time constant of the smoothing process by decreasing the time constant of the low-pass filter as the engine speed of the internal combustion engine increases. The greater the engine speed, the smaller the delay in air response, so the torque step is relaxed. Therefore, the response of the output torque can be improved while reducing the torque step by reducing the degree of the smoothing process when the engine speed is high.

  By the way, although the control apparatus of this Embodiment mentioned above is performing the low-pass filter process as an annealing process performed to a request | requirement torque, the method of an annealing process is not restricted to this. In other words, as long as the change rate of the required torque can be made slow, other filter processing may be performed, or the change may be gradually changed at a constant rate. Further, the adjustment of the degree of the annealing process is not limited to the means for changing the time constant of the filter process, and for example, the degree of the annealing process may be adjusted by changing the number of the annealing processes.

2 Target MBT torque calculation unit 4 In-cylinder air amount calculation unit 6 Throttle opening calculation unit 8 Estimated MBT torque calculation unit 10 Torque efficiency calculation unit 12 Smoothing processing unit 14 Changeover switch 16 Transient region determination unit 18 Ignition timing calculation unit

Claims (4)

In a control device for an internal combustion engine capable of controlling torque by the throttle opening and ignition timing,
Requested torque acquisition means for acquiring a required value of torque to be output to the internal combustion engine (hereinafter referred to as required torque);
Requested efficiency acquisition means for acquiring a required value (hereinafter referred to as required efficiency) of the ratio of the actually output torque to the potential torque that can be output by the internal combustion engine;
Required latent torque calculating means for calculating required latent torque by dividing the required torque by the required efficiency;
A required in-cylinder air amount calculating means for calculating an in-cylinder air amount (hereinafter referred to as a required in-cylinder air amount) necessary for realizing the required latent torque;
An opening command value determining means for determining an opening command value for the throttle based on the required in-cylinder air amount;
Estimated latent torque calculating means for calculating an estimated latent torque when the throttle is operated according to the opening command value;
Estimated efficiency calculating means for calculating a ratio of the required torque to the estimated latent torque (hereinafter, estimated efficiency);
When the required efficiency value is less than 1 and when a predetermined torque increase request is issued during idle operation of the internal combustion engine, the required torque used for calculating the estimated efficiency is An annealing process means for performing an annealing process to slow down the rate of change,
Ignition timing retard amount determining means for determining the retard amount of the ignition timing using the estimated efficiency as the instruction efficiency;
A control device for an internal combustion engine, comprising:   2. The internal combustion engine according to claim 1, wherein the smoothing processing means includes means for setting a processing degree of the smoothing process, and the processing degree is set higher as a change rate of the required torque is larger. Control device.   3. The smoothing processing means includes means for setting a processing degree of the smoothing process, and the processing degree is set lower as the engine speed of the internal combustion engine is larger. Control device for internal combustion engine.   The annealing processing means includes means for subjecting the required torque used for calculation of the estimated efficiency to a predetermined filter process for slowing the rate of change of the required torque, and changing a time constant of the filter process. 4. The control apparatus for an internal combustion engine according to claim 1, wherein a processing degree of the annealing process is set.

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