JP5125896B2 - Control device for internal combustion engine - Google Patents

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 whose operation is controlled by an opening degree of an intake air amount adjustment valve for adjusting an intake air amount and an 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 JP 2003-301766 A

  In the technique disclosed in Japanese Patent Laid-Open No. 2006-138300, the required torque and the torque margin value are set independently, but depending on the relationship between the required torque and the torque margin value, those in the internal combustion engine In some cases, this is not possible. This is a case where the in-cylinder combustion condition exceeds the combustion limit when the internal combustion engine is controlled by the throttle opening and ignition timing calculated from the input required torque and torque margin value. When the in-cylinder combustion conditions exceed the combustion limit, problems such as combustion fluctuations and misfires occur.

  As a countermeasure for such a problem, it is conceivable to correct each engine request (requested torque and torque margin value) set independently based on the mutual relationship. However, if the safety allowance for not exceeding the combustion limit is too large, the correction of the requirement becomes large and the accuracy of the requirement will be reduced.

  The present invention has been made to solve the above-described problems, and is a control device for an internal combustion engine capable of achieving both prevention of operation exceeding the combustion limit and achievement of engine requirements such as required torque. The purpose is to provide.

In order to achieve the above object, a first invention provides a control device for an internal combustion engine, the operation of which is controlled by the opening and ignition timing of an intake air amount adjustment valve that adjusts the intake air amount.
Request acquisition means for acquiring a plurality of predetermined physical quantity requests (hereinafter referred to as engine requests) for determining the operation of the internal combustion engine;
Target value calculating means for calculating a target valve opening and a target ignition timing for realizing each acquired engine request in the internal combustion engine based on each acquired engine request and the current operating state of the internal combustion engine; ,
The value of a predetermined intermediate variable used in the process of calculating the target valve opening or target ignition timing from each engine request so that the in-cylinder combustion conditions determined by the target valve opening and target ignition timing are within the combustion limit. Guard means for limiting the
Guard relaxation means for calculating the time change amount for at least one engine request, and relaxing the restriction by the guard means according to the calculated time change amount;
It is characterized by having.

According to a second invention, in the first invention,
The guard means has a strict guard value and a loose guard value as guard values for limiting the value of the predetermined intermediate variable,
The guard relaxation means instructs the guard means to switch from a strict guard value to a loose guard value when the calculated time variation exceeds a reference amount.

According to a third invention, in the second invention,
The guard relaxation means is characterized by instructing the guard means to switch to a strict guard value again after a predetermined time has elapsed since switching to a loose guard value.

According to a fourth invention, in the third invention,
The request acquisition means acquires a required torque and a required efficiency as an engine request,
The target value calculating means calculates a target valve opening from the acquired required torque and required efficiency, and also performs target ignition based on a torque efficiency that is a ratio of the required torque and a torque estimated from the current valve opening. Calculate the time,
The guard means provides a restriction on the value of the required efficiency used to calculate the target valve opening as the predetermined intermediate variable,
The guard relaxation means relaxes the restriction by the guard means according to the magnitude of the time change amount of the required torque or the required efficiency acquired by the request acquisition means.

A fifth invention is the fourth invention,
The guard means is provided with a restriction on each value as a predetermined intermediate variable, the required efficiency used for calculating the target valve opening and the torque efficiency used for calculating the target ignition timing,
The guard relaxation means changes the guard efficiency value of the torque efficiency from a loose guard value to a severe guard value after a predetermined time has elapsed since the guard value of the required efficiency has been switched from a loose guard value to a severe guard value. It is characterized by instructing to switch to.

  According to the first aspect of the present invention, by limiting the value of the predetermined intermediate variable used in the process of calculating the target valve opening or the target ignition timing, the in-cylinder combustion can be performed regardless of the value of each engine request. Conditions can be kept within the combustion limits. Further, the restriction on the predetermined intermediate variable is automatically relaxed according to the magnitude of the time change amount of the engine request, so that there is a request to change the predetermined physical quantity for determining the operation of the internal combustion engine quickly or largely. Can achieve a time change as required or as close as possible to the request.

  According to the second invention, the restriction of the predetermined intermediate variable and the relaxation of the restriction can be realized with simple logic. In addition, since switching from a strict guard value to a loose guard value is performed based on a comparison between the amount of time change required by the engine and a reference amount, there is an advantage that it is not necessary to supply instruction information for switching from the outside. is there.

  According to the third aspect of the invention, the strict guard value is switched again after a predetermined time has elapsed from the switching to the loose guard value, so that the in-cylinder combustion condition is temporarily changed while the loose guard value is selected. Even if the combustion limit is exceeded, it is possible to prevent the internal combustion engine from becoming unreasonable.

  According to the fourth aspect of the invention, a complicated logic for switching the guard value is not required by limiting only the required efficiency used for calculating the target valve opening. Further, by not limiting the torque efficiency used for calculating the target ignition timing, it is possible to widen the settable range of the ignition timing, and it is possible to realize high torque responsiveness with respect to changes in required torque.

  According to the fifth aspect, the torque efficiency used for calculating the target ignition timing is also limited, and when a predetermined time elapses after the guard value of the required efficiency is switched from the loose guard value to the strict guard value, the torque is The efficiency guard value can also be switched from a loose guard value to a strict guard value. Thus, even if the in-cylinder combustion condition temporarily exceeds the combustion limit while the torque efficiency guard value is relaxed, it is possible to prevent the internal combustion engine from becoming unreasonable.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 3.

  The internal combustion engine according to the present embodiment is a spark ignition internal combustion engine, and includes a throttle valve, an ignition device, and a fuel injection device as actuators for controlling the operation thereof. The control device of the present embodiment controls the internal combustion engine by so-called torque demand control, and a target value used for controlling each actuator based on various engine requirements including required torque, that is, a target throttle opening, A target ignition timing and a target A / F are calculated. The engine demand here is a demand value of a physical quantity that determines the operation of the internal combustion engine. Since the operation of the internal combustion engine can be determined by three physical quantities of torque, efficiency, and A / F (air / fuel ratio), the required torque, the required efficiency, and the required A / F are input as the engine request.

  The control device of the present embodiment is configured as shown in the block diagram of FIG. In FIG. 1, each element of the control device is indicated by a block, and signal transmission (main) between the blocks is indicated by an arrow. Hereinafter, the overall configuration and characteristics of the control apparatus of the present embodiment will be described with reference to FIG.

  The control apparatus of the present embodiment includes a required torque acquisition unit 2 that acquires torque required for an internal combustion engine, a required efficiency acquisition unit 4 that acquires efficiency required for the internal combustion engine, and A required for the internal combustion engine. A request A / F acquisition unit 6 for acquiring / F. Each request is issued from a host controller that controls the entire drive system of the vehicle.

  The control device according to the present embodiment is configured so that the target throttle opening degree and the target ignition are based on each input engine request (requested torque, required efficiency and required A / F) and engine information on the current operating state of the internal combustion engine. Time and target A / F are calculated. The torque realizing unit 10 performs the calculation. The torque realization unit 10 is an inverse model of the internal combustion engine, and includes a plurality of statistical models and physical models represented by maps and functions. The configuration of the inverse model of the internal combustion engine characterizes the control characteristics of the internal combustion engine by the control device. In the present embodiment, the required torque is realized with the highest priority among the required torque, the required efficiency, and the required A / F. It is configured.

  The required torque and the required efficiency that are input to the torque realization unit 10 are directly signals used for calculating the target throttle opening. Further, the request A / F input to the torque realization unit 10 is a signal directly used for calculating the target A / F. In order to control the operation of the internal combustion engine, in addition to these signals, a signal used for calculation of the target ignition timing is required, and the torque realization unit 10 is also provided with a function of generating the signal.

  The signal used for calculation of the target ignition timing in the control device of the present embodiment is torque efficiency. Torque efficiency is defined as the ratio of the required torque to the estimated torque of the internal combustion engine. The torque realization unit 10 includes an estimated torque calculation unit 112 and a torque efficiency calculation unit 114 as elements for calculating torque efficiency.

  The estimated torque calculator 112 estimates and calculates the torque of the internal combustion engine from the current throttle opening. More specifically, the amount of intake air that can be realized at the current throttle opening is calculated using an air model that is a physical model of the intake system. Next, the expected intake air amount calculated by the air model is collated with a torque map and converted into torque. The torque map is a statistical model showing the relationship between the torque and the intake air amount, and is a multidimensional map with a plurality of parameters including the intake air amount as axes. A value obtained from the current institution information is input to each parameter. However, the ignition timing is set to the optimal ignition timing (ignition timing more retarded of MBT and trace knock ignition timing). The estimated torque calculation unit 112 calculates the torque converted from the estimated intake air amount as the estimated torque at the optimal ignition timing of the internal combustion engine.

  The torque efficiency calculation unit 114 calculates a ratio between the required torque input to the torque achievement unit 10 and the estimated torque calculated by the estimated torque calculation unit 112 as torque efficiency. As will be described later, the throttle opening is controlled so as to realize a corrected required torque obtained by dividing the required torque by the required efficiency. This is to compensate for the torque that decreases by the required efficiency by increasing the intake air amount. However, since there is a delay in the response of the actual intake air amount to the change in the throttle opening, the actually outputable torque (estimated torque) has a response delay with respect to the change in the required efficiency. The torque efficiency, which is the ratio between the estimated torque and the required torque, is a parameter for reflecting both the required efficiency and the actual change in the intake air amount in the calculation of the target ignition timing. At least in a steady state where the intake air amount is constant, theoretically, the estimated torque matches the required correction torque, and the torque efficiency matches the required efficiency.

  By the way, the required torque, the required efficiency, and the required A / F issued from the host control system of the vehicle drive system to the internal combustion engine are generated independently of each other and can be realized in relation to other engine requirements. Whether or not is considered. For this reason, there is a possibility that the in-cylinder combustion conditions may exceed the combustion limit depending on the relationship between the magnitudes of the engine requirements. Therefore, the torque realizing unit 10 is provided with a correcting unit 20 that corrects the magnitude of a signal used for each control of the internal combustion engine so that the internal combustion engine can be properly operated. The configuration and function of the correction unit 20 will be described in detail later.

  As a result of the processing by the correction unit 20, the main signals used for calculation of each target value for controlling the actuator are the corrected required torque, the required efficiency, the required A / F, and the torque efficiency. The torque achievement unit 10 calculates the target throttle opening based on the corrected required torque and the required efficiency. Also. The torque achievement unit 10 calculates the target ignition timing based on the corrected torque efficiency. In addition, the torque achievement unit 10 calculates the corrected request A / F as the target A / F.

  The torque realization unit 10 includes a required torque correction unit 102, an intake air amount calculation unit 104, and a throttle opening calculation unit 106 for calculating the target throttle opening. The required torque and the required efficiency after correction are input to the required torque correction unit 102. The required torque correction unit 102 corrects the required torque by dividing it by the required efficiency, and outputs the required torque after the efficiency correction to the target air amount calculation unit 104. If the value of the required efficiency after correction is smaller than 1, the required torque is increased by division by the required efficiency, and the increased required torque is supplied to the intake air amount calculation unit 104.

  The intake air amount calculation unit 104 converts the efficiency-corrected required torque into an intake air amount. An air amount map is used to convert the required torque into the intake air amount. The air amount map is a statistical model showing the relationship between torque and intake air amount, and is a multi-dimensional map with a plurality of parameters including torque as axes. A value obtained from the current institution information is input to each parameter. However, the ignition timing is the optimum ignition timing. The intake air amount calculation unit 104 calculates the intake air amount converted from the efficiency-corrected required torque as the target intake air amount.

  The throttle opening calculation unit 106 calculates a throttle opening for realizing the target intake air amount. An inverse model of the air model (hereinafter, air inverse model) is used for the calculation. In the calculation using the air model, engine information regarding various operating states that affect the intake air amount such as the engine speed and valve timing is used. The throttle opening calculation unit 106 outputs the throttle opening converted from the target intake air amount as the target throttle opening.

  The torque achievement unit 10 includes an ignition timing calculation unit 116 for calculating the target ignition timing from the corrected torque efficiency. The ignition timing calculation unit 116 calculates a retard amount with respect to the optimal ignition timing from the corrected torque efficiency. A statistical model such as a map is used to calculate the retard amount. The smaller the torque efficiency, the larger the ignition retard amount. The ignition timing calculation unit 116 calculates the optimal ignition timing based on the operating state of the internal combustion engine. The ignition timing calculation unit 116 adds the ignition retardation amount to the optimal ignition timing, and outputs the obtained final ignition timing as the target ignition timing.

  This completes the description of the basic configuration of the torque achievement unit 10. Next, the configuration and function of the correction unit 20 which is a main part for the control device of the present embodiment will be described.

  The correction unit 20 includes guard units 202, 212, 232, and 214 for limiting the values of the required torque, the required efficiency, the required A / F, and the torque efficiency to predetermined ranges. The required torque, the required efficiency, the required A / F, and the torque efficiency are all common in that they are intermediate variables used inside the torque achievement unit 10. The guard values set in the guard sections 202, 212, 232, and 214 are variable, and appropriate values are set according to the internal combustion operation state.

  The guard value set in the required torque guard unit 202 is read from the torque limit value map 204. The torque limit value map 204 stores a torque value corresponding to the combustion limit in association with the engine speed or the like. In addition, the guard value set in the request A / F guard unit 232 is read from the A / F limit value map 234. The A / F limit value map 232 stores the A / F value corresponding to the combustion limit in association with the engine speed, the required torque, the required efficiency, and the like.

  The same guard value is set in the required efficiency guard unit 212 and the torque efficiency guard unit 214. The correction unit 20 prepares two types of efficiency limit value maps used for setting guard values for the guard units 212 and 214. Although the two efficiency limit value maps 218 and 220 are common in that the efficiency guard value is stored in association with the engine speed or the like, a guard value is set between the two efficiency limit value maps 218 and 220. There is a difference.

  FIG. 2 is a diagram showing two efficiency limit value maps 218 and 220 in comparison. FIG. 2 shows the relationship between the efficiency guard value (lower limit value) and the engine speed. In FIG. 2, when compared at the same engine speed, the first efficiency limit value map 218 takes a higher guard value, that is, a stricter guard value. In the first efficiency limit value map 218, an efficiency value corresponding to the drivability limit is set as a guard value. The drivability limit is a limit value that can maintain good drivability as long as the efficiency value is higher than that and does not affect the durability of the internal combustion engine even when used for a long time. The drivability limit corresponds to the theoretical combustion limit. Hereinafter, the dribabil limit is referred to as the long-time limit.

  On the other hand, when compared at the same engine speed, the second efficiency limit value map 220 takes a lower guard value, that is, a gentler guard value. In this efficiency limit value map 220, an efficiency value corresponding to the OT limit exceeding the theoretical combustion limit is set as the guard value. The OT limit is a limit value that can be used for a short period of time (for example, about 500 msec), although it may impair the durability of the internal combustion engine due to overheating when used for a long time. Hereinafter, the OT limit is referred to as a short-time limit.

  The correction unit 20 includes a selection unit 216 for selecting the efficiency limit value maps 218 and 220 to be used, and a switching instruction unit 222 for instructing the selection unit 216 to switch the selection. The selection unit 216 selects one of the two efficiency limit value maps 218 and 220 in accordance with an instruction from the switching instruction unit 222. The required efficiency guard unit 212 and the torque efficiency guard unit 214 are set with guard values read from the map selected by the selection unit 216.

  The switching instruction unit 222 instructs selection switching according to the following switching rule. First, the basic selection by the selection unit 216 is the first efficiency limit value map 218. That is, basically, each of the required efficiency and the torque efficiency is limited by a strict guard value corresponding to the long-time limit.

The selection switching from the first efficiency limit value map 218 to the second efficiency limit value map 220 is performed only when any of the following switching conditions is satisfied.
(1) The amount of change in required torque per predetermined time exceeds a predetermined switching reference amount.
(2) The amount of change in required efficiency per predetermined time exceeds a predetermined switching reference amount.
That is, when there is a request to change torque or efficiency quickly or greatly, switching from a strict guard value corresponding to the long-time limit to a loose guard value corresponding to the short-time limit is performed. In this case, since only the required torque and the required efficiency are necessary for the determination of switching, it is not necessary to supply the instruction information for switching from the outside of the torque achievement unit 10.

  Then, when the predetermined time has elapsed after switching to the second efficiency limit value map 220, switching to the first efficiency limit value map 218 is performed again. The predetermined time is a time during which the guard value corresponding to the short time limit can be continuously used. When a loose guard value is selected, the in-cylinder combustion condition may temporarily exceed the combustion limit during that time, but it is possible to switch to a strict guard value again before the continuous usable time is exceeded. Therefore, it is possible to prevent the internal combustion engine from becoming unreasonable. Also in this case, it is not necessary to supply instruction information for switching from the outside of the torque achievement unit 10.

  An example of the result of the switching instruction unit 222 operating according to the switching rules as described above is shown in FIG. FIG. 3 shows changes with time in required torque, required efficiency, torque efficiency, efficiency guard value, throttle opening, and ignition timing in order from the top. FIG. 3 shows two examples (A) and (B).

  First, the example of (A) will be described. In this example, the operation when the required torque input to the torque realizing unit 10 is rapidly reduced is shown. There is no change in required efficiency. The aforementioned switching condition is satisfied when the required torque rapidly decreases. Thereby, the efficiency guard value set in the required efficiency guard unit 212 and the torque efficiency guard unit 214 is switched from a strict guard value corresponding to the long-time limit to a loose guard value corresponding to the short-time limit.

  In addition, the throttle opening changes so as to realize a change in the required torque, but the intake air amount changes behind the change in the throttle opening. For this reason, the torque efficiency, which is the ratio between the estimated torque calculated from the intake air amount and the required torque, suddenly decreases as the required torque decreases rapidly.

  At this time, if the efficiency guard value of the torque efficiency guard unit 214 is a strict guard value corresponding to the long-time limit, the sudden decrease in torque efficiency is limited by the efficiency guard value. In that case, the retard amount of the ignition timing becomes insufficient, and the actual torque cannot be reduced as required.

  In this regard, in the present embodiment, as described above, the efficiency guard value of the torque efficiency guard unit 214 is switched to a loose guard value corresponding to the short-time limit in accordance with the sudden decrease in the required torque. For this reason, the value of the torque efficiency is not limited by the efficiency guard value, and the ignition timing can be sufficiently retarded so as to compensate for the torque difference between the required torque and the estimated torque.

  Thereafter, when a predetermined time (500 msec in this case) has elapsed since the efficiency guard value was switched to a loose guard value corresponding to the short-time limit, the efficiency guard value is switched again to a strict guard value corresponding to the long-time limit. .

  Next, the example of (B) will be described. In this example, the operation when both the required torque and the required efficiency that are input to the torque achievement unit 10 are rapidly and rapidly reduced is shown. The aforementioned switching condition is satisfied when both the required torque and the required efficiency rapidly decrease. Thereby, the efficiency guard value set in the required efficiency guard unit 212 and the torque efficiency guard unit 214 is switched from a strict guard value corresponding to the long-time limit to a loose guard value corresponding to the short-time limit.

  Here, the required efficiency after the efficiency correction, which is the basis for calculating the target intake air amount, is kept constant by reducing the required efficiency as the required torque decreases. As a result, the target intake air amount is constant before and after the change in the required torque, and the throttle opening is kept constant. In this case, since the estimated torque calculated from the throttle opening is also constant, the torque efficiency, which is the ratio between the estimated torque and the required torque, changes in accordance with the change in the required torque.

  Here, if the efficiency guard value of the required efficiency guard unit 212 remains a strict guard value corresponding to the limit for a long time, the sudden decrease in the required efficiency is limited by the efficiency guard value. In that case, the required torque increase due to the required efficiency becomes insufficient, the target intake air amount temporarily decreases before and after the change of the required torque, and the throttle opening also temporarily changes to the closing side accordingly. It will be. When the throttle opening temporarily changes to the closing side, the estimated torque calculated based on the throttle opening also temporarily decreases. As a result, the change in the torque efficiency, which is the ratio between the estimated torque and the required torque, decreases, and the ignition retard amount calculated in accordance with the torque efficiency decreases. In other words, the actual efficiency cannot be lowered as required.

  On the other hand, if the efficiency guard value of the torque efficiency guard unit 214 remains a strict guard value corresponding to the long-time limit, the change of the torque efficiency to the decreasing side is limited by the efficiency guard value. In that case, the retard amount of the ignition timing becomes insufficient, and the actual torque cannot be reduced as required.

  With regard to these points, in the present embodiment, as described above, the efficiency guard values of the required efficiency guard unit 212 and the torque efficiency guard unit 214 correspond to the short-time limit according to the temporary decrease in the required torque and the required efficiency. Temporarily switch to a loose guard value. For this reason, neither the required torque nor the torque efficiency is limited by the efficiency guard value, and the required torque and efficiency can be realized in the internal combustion engine.

  Also in this example, the efficiency guard value is switched again to a strict guard value corresponding to the long-time limit when a predetermined time elapses after the efficiency guard value is switched to the loose guard value corresponding to the short-time limit.

  According to the correction unit 20 having the configuration and functions as described above, the guard units 202, 212, 232, and 214 are provided for the required torque, the required efficiency, the required A / F, and the torque efficiency, respectively. Regardless of the required torque, required efficiency, and required A / F values, the in-cylinder combustion conditions can be within the combustion limit. Further, since the required efficiency and the guard value for limiting the torque efficiency are automatically relaxed in accordance with the required torque and the amount of time change in the required efficiency, there is a demand to change the torque and the efficiency quickly or largely. In some cases, it is possible to realize a time change as requested or as close as possible to the request.

  The first embodiment of the present invention has been described above. The first embodiment embodies the first, second and third aspects of the present invention. Specifically, in the configuration shown in FIG. 1, the required torque acquisition unit 2, the required efficiency acquisition unit 4, and the required A / F acquisition unit 6 correspond to the “request acquisition unit” of the first invention. The request A / F corresponds to an “institution request”. The torque achievement unit 10 corresponds to the “target value calculation means” of the first invention. The required efficiency guard unit 212 and the torque efficiency guard unit 214 and the two efficiency limit maps 218 and 220 constitute the “guard means” of the first and second aspects of the invention. It corresponds to “variable”. The selection unit 216 and the switching instruction unit 222 constitute the “guard mitigation means” of the first, second, and third inventions.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS.

  The overall configuration of the control device of the present embodiment is shown in the block diagram of FIG. However, the control device according to the present embodiment and the control device according to the first embodiment are different in the configuration of the correction unit 20 that is one element constituting the control device. FIG. 4 is a block diagram showing the configuration of the main part of the correction unit 20 according to the present embodiment. That is, the configuration of the control device of the present embodiment is obtained by replacing a part of the configuration shown in FIG. 1 with the configuration shown in FIG. Hereinafter, the configuration of the correction unit 20, which is a feature of the present embodiment, will be described with reference to FIG. 4 together with FIG. 1.

  The correction unit 20 according to the present embodiment does not include a guard unit for limiting the value of torque efficiency. On the other hand, a required efficiency guard unit 212 for limiting the required efficiency value is provided. One of the two efficiency limit value maps 218 and 220 is selected by the selection unit 216 in accordance with the instruction from the switching instruction unit 222, and the efficiency guard value read from the selected map is set in the required efficiency guard unit 212. .

  According to the configuration shown in FIG. 4, the guard unit 212 is provided only for the required efficiency used for calculating the target throttle opening, so that there is an advantage that complicated logic for switching guard values is not necessary. In addition, by not limiting the torque efficiency used for calculating the target ignition timing, it is possible to widen the settable range of the ignition timing, and to realize high torque responsiveness to changes in the required torque. There are also advantages.

  FIG. 5 is a diagram illustrating an example of a result of the switching instruction unit 222 operating in the correction unit 20 according to the present embodiment. Note that the switching rules followed by the switching instruction unit 222 are as described in the first embodiment. FIG. 5 shows changes over time in the estimated torque, the required torque, the required efficiency, the required efficiency guard value, the throttle opening, and the ignition timing in order from the top.

  The example shown in FIG. 5 shows an operation when the efficiency guard value of the required efficiency guard unit 212 is switched from a loose guard value corresponding to the short time limit to a strict guard value corresponding to the long time limit. Here, it is assumed that the required efficiency value a1 input to the required efficiency guard unit 212 is lower than the efficiency guard value corresponding to the short-time limit. In this case, before the efficiency guard value is switched, the efficiency guard value corresponding to the short-time limit becomes the required efficiency value a <b> 2 output from the required efficiency guard unit 212. After the efficiency guard value is switched, the efficiency guard value corresponding to the long-time limit becomes the required efficiency value a2 output from the required efficiency guard unit 212. That is, the required efficiency value a2 changes suddenly before and after the efficiency guard value is switched. The sudden change in the required efficiency value a2 is reflected in the target throttle opening calculated using the required efficiency, and further reflected in the estimated torque value calculated based on the throttle opening. As the estimated torque changes, the torque efficiency, which is the ratio between the estimated torque and the required torque, also changes.

  At this time, if the same efficiency guard value multiplied by the required efficiency is also multiplied by the torque efficiency, when the efficiency guard value is switched to a strict guard value corresponding to the long-time limit, The value of torque efficiency will increase rapidly. If the torque efficiency increases rapidly, the ignition timing is suddenly advanced, and the ignition timing is excellent in torque response, so that a torque step occurs due to a sudden increase in torque.

  In this regard, in the present embodiment, as described above, the torque efficiency value is not limited by the efficiency guard value. Therefore, the torque efficiency value does not change suddenly before and after the efficiency guard value is switched. In this case, the torque efficiency increases as the estimated torque decreases, and the ignition timing is returned to the advance side as the difference between the estimated torque and the required torque decreases.

  The second embodiment of the present invention has been described above. The second embodiment embodies the first, second, third and fourth aspects of the present invention. Specifically, in the configuration shown in FIG. 1, the required torque acquisition unit 2 and the required efficiency acquisition unit 4 correspond to the “request acquisition unit” of the fourth invention, and the torque realization unit 10 outputs the “target value calculation” of the fourth invention. It corresponds to “means”. In the configuration shown in FIG. 4, the required efficiency guard unit 212 and the two efficiency limit maps 218 and 220 constitute the “guard means” of the fourth invention. The selection unit 216 and the switching instruction unit 222 constitute the “guard mitigation means” of the fourth invention. The correspondence relationship with the first, second and third inventions of the second embodiment is the same as that of the first embodiment.

Embodiment 3 FIG.
Next, Embodiment 3 of the present invention will be described with reference to FIG. 1, FIG. 6, and FIG.

  The overall configuration of the control device of the present embodiment is shown in the block diagram of FIG. However, the control device according to the present embodiment and the control device according to the first embodiment are different in the configuration of the correction unit 20 that is one element constituting the control device. FIG. 6 is a block diagram showing a configuration of a main part of the correction unit 20 according to the present embodiment. That is, the configuration of the control device of the present embodiment is obtained by replacing a part of the configuration shown in FIG. 1 with the configuration shown in FIG. Hereinafter, the configuration of the correction unit 20 that is a feature of the present embodiment will be described with reference to FIG.

  The correction unit 20 according to the present embodiment is implemented in that it includes a required efficiency guard unit 212 for limiting the required efficiency value and a torque efficiency guard unit 214 for limiting the torque efficiency value. Common to Form 1. However, there is a difference in the function of the selection unit 216 that sets a guard value in these guard units 212 and 214.

  The selection unit 216 according to the present embodiment switches the efficiency guard value of the required efficiency guard unit 212 from a loose guard value corresponding to the short time limit to a strict guard value corresponding to the long time limit, and then a predetermined time has elapsed. After that, the efficiency guard value of the torque efficiency guard unit 214 is switched from a loose guard value corresponding to the short time limit to a strict guard value corresponding to the long time limit. That is, a time difference is provided between the required efficiency guard unit 212 and the torque efficiency guard unit 214 in switching from a loose guard value to a strict guard value. The time difference for switching is set in accordance with the response delay time of the estimated torque with respect to the required torque.

  When this embodiment is compared with the second embodiment, this embodiment has the following advantages. According to the second embodiment, the torque efficiency used for calculating the target ignition timing is not limited by the efficiency guard value, so that it is possible to prevent the occurrence of a torque step associated with the switching of the efficiency guard value. However, since the torque efficiency value is allowed to exceed the combustion limit, in some cases, the internal combustion engine may become unreasonable. On the other hand, according to the present embodiment, the torque efficiency is also limited by the efficiency guard value, so that the torque efficiency value is prevented from exceeding the combustion limit for a long time. Further, since the efficiency guard value of the torque efficiency guard unit 214 is switched after the efficiency guard value of the required efficiency guard unit 212 is switched, the torque efficiency changes following the required efficiency within the time difference. . As a result, when the efficiency guard value is switched, the difference between the torque efficiency value and the severe guard value after switching is reduced, and the occurrence of a torque step due to switching is suppressed.

  FIG. 7 is a diagram illustrating an example of a result of the switching instruction unit 222 operating in the correction unit 20 according to the present embodiment. Note that the switching rules followed by the switching instruction unit 222 are as described in the first embodiment. FIG. 7 shows changes in estimated torque, required torque, required efficiency, torque efficiency, required efficiency guard value, torque efficiency guard value, throttle opening, and ignition timing over time, in that order from the top.

  The example shown in FIG. 7 shows an operation when the efficiency guard value c of the required efficiency guard unit 212 is switched from a loose guard value corresponding to the short time limit to a strict guard value corresponding to the long time limit. Here, it is assumed that the required efficiency value a1 input to the required efficiency guard unit 212 is lower than the efficiency guard value c corresponding to the short-time limit. In this case, before the efficiency guard value c is switched, the efficiency guard value corresponding to the short time limit becomes the required efficiency value a <b> 2 output from the required efficiency guard unit 212. After the efficiency guard value is switched, the efficiency guard value corresponding to the long-time limit becomes the required efficiency value a2 output from the required efficiency guard unit 212. That is, the required efficiency value a2 changes suddenly before and after the efficiency guard value c is switched.

  The sudden change in the required efficiency value a2 is reflected in the target throttle opening calculated using the required efficiency, and further reflected in the estimated torque value calculated based on the throttle opening. As the estimated torque changes, the torque efficiency b, which is the ratio between the estimated torque and the required torque, also changes. The torque efficiency b changes following the required efficiency and eventually converges to an efficiency guard value corresponding to the long-time limit.

  When a predetermined time elapses after the efficiency guard value c of the required efficiency guard unit 212 is switched, the efficiency guard value d of the torque efficiency guard unit 214 corresponds to the long time limit from the loose guard value corresponding to the short time limit. Can be switched to a strict guard value. Since a switching time difference is provided in accordance with the response delay time of the estimated torque with respect to the required torque, the torque efficiency b at this point converges to an efficiency guard value corresponding to a substantially long time limit. Therefore, there is no torque step generated by switching the efficiency guard value d, or it is suppressed to an extremely small value.

  The third embodiment of the present invention has been described above. The third embodiment embodies the first, second, third, fourth, and fifth inventions of the present invention. Specifically, in the configuration shown in FIG. 6, the required efficiency guard unit 212 and the torque efficiency guard unit 214 and the two efficiency limit maps 218 and 220 constitute the “guard means” of the fifth invention. Further, the “guard mitigating means” of the fifth aspect of the invention is configured by the selection unit 216 and the switching instruction unit 222. The correspondence relationship with the first, second, third and fourth inventions of the third embodiment is the same as that of the first embodiment.

Others.
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the throttle valve is used as the intake air amount adjustment valve for adjusting the intake air amount, but an intake valve with a variable valve mechanism may be used. In this case, the target valve opening of the intake air amount adjusting valve is a target value of the lift amount or operating angle of the intake valve.

  In the above-described embodiment, two types of efficiency limit value maps are prepared. However, more maps may be prepared and switched according to the required torque and the amount of change in required efficiency over time. Or you may make it change a guard value continuously according to the amount of time change of request torque or request efficiency.

  Further, in the above-described embodiment, the guard values for the required efficiency and the torque efficiency are switched, but the guard values for the required A / F may be switched in addition to or instead of the guard values. Further, a guard may be provided in an intermediate variable other than the required efficiency, torque efficiency, or required A / F, and the guard value may be relaxed according to the time change amount of the engine required value.

It is a block diagram which shows the structure of the control apparatus of the internal combustion engine as Embodiment 1 of this invention. It is a figure which compares and shows two efficiency limit value maps concerning Embodiment 1 of this invention. It is a figure which shows an example of the result as which the switching instruction | indication part operate | moved in the correction part concerning Embodiment 1 of this invention. It is a block diagram which shows the structure of the principal part of the correction part concerning Embodiment 2 of this invention. It is a figure which shows an example of the result of having operated the switch instruction | indication part in the correction part concerning Embodiment 2 of this invention. It is a block diagram which shows the structure of the principal part of the correction part concerning Embodiment 3 of this invention. It is a figure which shows an example of the result as which the switching instruction | indication part operate | moved in the correction part concerning Embodiment 3 of this invention.

Explanation of symbols

2 required torque acquisition unit 4 required efficiency acquisition unit 6 required A / F acquisition unit 10 torque realization unit 20 correction unit 102 required torque correction unit 104 intake air amount calculation unit 106 throttle opening calculation unit 112 estimated torque calculation unit 114 torque efficiency calculation Unit 116 ignition timing calculation unit 202 required torque guard unit 204 torque limit value map 212 required efficiency guard unit 214 torque efficiency guard unit 216 selection unit 218 efficiency limit value map (long-time limit)
220 Efficiency limit value map (short time limit)
222 Switching instruction part 232 Request A / F guard part 234 A / F limit value map

Claims (5)

In a control device for an internal combustion engine, the operation of which is controlled by the opening and ignition timing of an intake air amount adjustment valve that adjusts the intake air amount.
Request acquisition means for acquiring a plurality of predetermined physical quantity requests (hereinafter referred to as engine requests) for determining the operation of the internal combustion engine;
Target value calculating means for calculating a target valve opening and a target ignition timing for realizing each acquired engine request in the internal combustion engine based on each acquired engine request and the current operating state of the internal combustion engine; ,
The value of a predetermined intermediate variable used in the process of calculating the target valve opening or target ignition timing from each engine request so that the in-cylinder combustion conditions determined by the target valve opening and target ignition timing are within the combustion limit. Guard means for limiting the
Guard relaxation means for calculating the time change amount for at least one engine request, and relaxing the restriction by the guard means according to the calculated time change amount;
A control device for an internal combustion engine, comprising: The guard means has a strict guard value and a loose guard value as guard values for limiting the value of the predetermined intermediate variable,
2. The internal combustion engine according to claim 1, wherein the guard relaxation means instructs the guard means to switch from a strict guard value to a loose guard value when the calculated time change amount exceeds a reference amount. Control device.   3. The internal combustion engine according to claim 2, wherein the guard relaxation unit instructs the guard unit to switch to a strict guard value again after a predetermined time has elapsed since the switching to the gentle guard value. Control device. The request acquisition means acquires a required torque and a required efficiency as an engine request,
The target value calculating means calculates a target valve opening from the acquired required torque and required efficiency, and also performs target ignition based on a torque efficiency that is a ratio of the required torque and a torque estimated from the current valve opening. Calculate the time,
The guard means provides a restriction on the value of the required efficiency used to calculate the target valve opening as the predetermined intermediate variable,
4. The internal combustion engine according to claim 3, wherein the guard relaxation means relaxes the restriction by the guard means according to the amount of time change in the required torque or the required efficiency acquired by the request acquisition means. Control device. The guard means is provided with a restriction on each value as a predetermined intermediate variable, the required efficiency used for calculating the target valve opening and the torque efficiency used for calculating the target ignition timing,
The guard relaxation means changes the guard efficiency value of the torque efficiency from a loose guard value to a severe guard value after a predetermined time has elapsed since the guard value of the required efficiency has been switched from a loose guard value to a severe guard value. 5. The control apparatus for an internal combustion engine according to claim 4, wherein an instruction to switch to is issued.

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