JP5673369B2 - 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 that determines a target throttle opening for realizing a required intake air amount using an air inverse model.

  As disclosed in Japanese Patent Application Laid-Open No. 2009-299666, a method of calculating a target throttle opening using an inverse model of an air model (referred to as an air inverse model) is known. The air model models the response of the intake air amount with respect to the operation of the throttle, and expresses it by a mathematical expression. For example, the air model can be composed of a throttle model, an intake pipe model, and an intake valve model. The throttle model is a calculation model in which the relationship between the throttle opening and the throttle passage flow rate is expressed by a mathematical expression. The intake pipe model is a calculation model in which the relationship between the throttle passage flow rate and the intake air amount and the intake pipe pressure is expressed by a mathematical expression. The intake valve model is a calculation model that expresses the relationship between the intake pipe pressure and the intake air amount by a mathematical expression. Since the air inverse model calculates such an air model in the reverse direction, the target throttle opening required to realize the required intake air amount can be accurately calculated by using the air inverse model.

JP 2009-299666 A

  By the way, the throttle passage flow rate increases as the throttle is greatly opened. However, when the throttle opening degree increases to some extent, the throttle passage flow rate does not change so much with respect to the change in the throttle opening degree. When the throttle opening is in such a dead zone region, the sensitivity of the throttle opening calculated in the air inverse model to the flow rate through the throttle is very high. For this reason, the target throttle opening greatly changes with respect to a minute change in the required intake air amount.

  However, since there is a limit to the operating speed of the throttle, if the amount of change in the target throttle opening is large, it takes time until the actual throttle opening reaches the target throttle opening. . For this reason, at the time of engine deceleration in which the required intake air amount is greatly reduced, it takes time for the throttle opening to get out of the dead zone, and a response delay of the actual intake air amount with respect to the required intake air amount occurs. Such a response delay of the intake air amount acts in a direction that impairs the deceleration performance of the internal combustion engine. On the other hand, as far as acceleration performance is concerned, even with the conventional method for calculating the target throttle opening, the acceleration performance could be sufficiently obtained. This is because when the engine speed is increased, the flow rate of air passing through the throttle increases as the engine speed increases, so that the dead zone of the throttle opening disappears and there is no response delay of the intake air amount associated with the dead zone as during deceleration. .

  The present invention has been made in view of the above-described problems. In an internal combustion engine control apparatus that determines a target throttle opening for realizing a required intake air amount by using an air inverse model, the deceleration of the internal combustion engine is determined. The purpose is to make it possible to fully draw out the performance together with the acceleration performance.

In order to achieve the above object, according to a first aspect of the present invention, in a control apparatus for an internal combustion engine that controls a throttle according to a target throttle opening, a target throttle opening for realizing a required intake air amount is determined using an air inverse model. Target throttle opening calculating means for calculating, guard value determining means for determining a throttle opening guard value for setting an upper limit on the throttle opening according to the engine speed, and a target calculated using the air inverse model comprising a guard unit for performing a release of restriction by the throttle opening guard value for the throttle opening degree and limitations, and the air inverse model includes at least a process of calculating the required intake pipe pressure from the required intake air amount, A process of calculating a virtual intake pipe pressure corresponding to the current value of the intake pipe pressure from the actual throttle opening, and the required intake pipe pressure and the virtual intake pipe pressure Configured to execute a process of calculating a pressure and a process of calculating the target throttle opening based on the differential pressure, and the guard means has the target throttle opening not less than a predetermined value, and When the differential pressure is less than or equal to a threshold, the target throttle opening is limited by the throttle opening guard value, and the target throttle opening is smaller than the predetermined value or the differential pressure is larger than the threshold. The restriction of the target throttle opening by the throttle opening guard value is released .

  According to a second aspect of the present invention, in the first aspect, the guard value determining means changes the throttle flow rate with respect to a change in the throttle opening in a region where the operation of the throttle is limited by the throttle opening guard value. The throttle opening guard value is determined so as to include a dead zone with low responsiveness.

  According to the present invention, the target throttle opening is limited by the throttle opening guard value, so that the throttle is operated in a region where a change in the intake air amount equal to or greater than a certain value can be obtained with respect to the change in the throttle opening. For this reason, when the required intake air amount decreases due to a deceleration request, the throttle can be moved to quickly decrease the intake air amount. On the other hand, at the time of acceleration of the internal combustion engine in which the dead zone region decreases, the restriction of the target throttle opening by the throttle opening guard value is released, so that the throttle can be greatly opened to greatly increase the intake air amount. Thus, according to the present invention, the deceleration performance of the internal combustion engine can be sufficiently extracted together with the acceleration performance.

It is a functional block diagram which shows the structure of the control apparatus of embodiment of this invention. It is a graph which shows the relationship between the throttle opening of regular time, and the throttle passage air amount. It is a flowchart which shows operation | movement of the throttle opening guard with which the control apparatus of embodiment of this invention is provided. It is a time chart which shows the operation image at the time of steady state and acceleration / deceleration of the internal combustion engine controlled by the control device of the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The internal combustion engine to which the control device of the present embodiment is applied is a four-cycle reciprocating engine that can control torque by adjusting the amount of air with a throttle. The present control device is realized as a function of an ECU provided in the internal combustion engine. Specifically, the ECU functions as a control device when a program stored in the memory is executed by the CPU. When the ECU functions as a control device, the ECU calculates the target throttle opening according to the programmed throttle opening calculation logic, and controls the operation of the throttle according to the target throttle opening.

  FIG. 1 is a diagram expressing the contents of the throttle opening calculation logic used in the present embodiment by a plurality of functional blocks. As shown in this figure, this throttle opening calculation logic includes a required torque conversion map 4, a required air amount conversion map 6, an air inverse model 10, a throttle opening guard 22, and a throttle opening guard value calculation map 24. Yes. Hereinafter, the contents of each element included in the throttle opening degree calculation logic of the present embodiment will be described.

  The required torque conversion map 4 is a map for converting the opening degree of the accelerator pedal into the required torque. The required torque obtained in the required torque conversion map 4 is the driver required torque that the driver requests to the internal combustion engine through the operation of the accelerator pedal. The required torque handled by the throttle opening calculation logic includes a device required torque required by a vehicle control device such as a TRC in addition to the driver required torque. However, illustration of the device required torque and its generation source is omitted.

  The required air amount conversion map 6 uses torque and intake air amount (or charge efficiency or load factor obtained by making it non-dimensional) as keys for various engine state amounts including engine speed, ignition timing, and air-fuel ratio. Associated map. In the required air amount conversion map 6, an intake air amount (hereinafter referred to as a required KL) required for realizing the required torque under the current engine state amount is calculated.

  In detail, the air reverse model 10 is configured by combining an intake valve reverse model 12, an intake pipe reverse model 14, a throttle reverse model 16, a throttle operation model 20, and a simple air model 30. Of these, the intake valve inverse model 12 is an experiment-based model in which the relationship between the intake air amount and the intake pipe pressure is examined. According to empirical rules obtained through experiments, in the intake valve inverse model 12, the relationship between the intake air amount and the intake pipe pressure is approximated by a straight line. By inputting the request KL to the intake valve reverse model 12, an intake pipe pressure (hereinafter referred to as request Pm) required for realizing the request KL is calculated.

  The intake pipe inverse model 14 is a physical model constructed based on a conservation law regarding air in the intake pipe, specifically, an energy conservation law and a flow rate conservation law. In the intake pipe inverse model 14, the relationship between the flow rate of air passing through the throttle and the intake pipe pressure is expressed by a mathematical expression. The differential pressure (hereinafter referred to as ΔPm) between the required KL and the current virtual intake pipe pressure (hereinafter referred to as virtual Pm), the current virtual intake air amount (hereinafter referred to as virtual KL), and 1 By inputting the request KL before the step into the intake pipe inverse model 14, a throttle passage flow rate (hereinafter referred to as request mt) required for realizing the request Pm is calculated.

  The throttle inverse model 16 is a model that expresses the relationship between the throttle passage flow rate and the throttle opening by a mathematical expression. The flow rate through the throttle can be calculated using the flow area determined by the throttle opening and the pressure ratio before and after the throttle. The pressure ratio used for the calculation of the throttle passage flow rate may be an actual measurement value or a calculation value based on a model. By inputting the request mt to the throttle inverse model 16, a target throttle opening degree (hereinafter referred to as target TA) for realizing the request mt is calculated.

  The throttle operation model 20 and the simple air model 30 are provided for calculating the virtual Pm and the virtual KL used in the above calculation process from the actual throttle opening (hereinafter referred to as actual TA). The throttle operation model 20 is a model that approximates the relationship between the operation of the throttle 2 and an input signal that causes the operation by a mathematical expression or the like. By inputting the actual TA to the throttle operation model 20, an input signal corresponding to the actual TA, that is, a virtual value of the target TA is calculated.

  The simple air model 30 includes a throttle model 32, an intake pipe model 34, and an intake valve model 36. Among them, the throttle model 32 is a forward model corresponding to the throttle reverse model 16 described above. By inputting a virtual value of the target TA to the throttle model 32, the current virtual throttle passage flow rate (hereinafter referred to as virtual mt) is calculated. The intake pipe model 34 is a forward model corresponding to the intake pipe inverse model 14 described above, and calculates a virtual Pm by inputting a virtual mt. The intake valve model 36 is a forward model corresponding to the intake valve inverse model 12 described above, and calculates a virtual KL by inputting virtual Pm. As described above, the virtual Pm is used for calculating ΔPm, and the virtual KL is input to the intake pipe inverse model 14 together with ΔPm.

  The throttle opening guard 22 is provided in the signal line from the throttle reverse model 16 of the air reverse model 10 to the throttle 2 in the throttle opening calculation logic. The throttle opening guard 22 is means for limiting the target TA with the throttle opening guard value described later as an upper limit. Specifically, if the target TA input from the throttle inverse model 16 is equal to or less than the throttle opening guard value, the target TA is output to the throttle 2 as it is. On the other hand, if the target TA input from the throttle inverse model 16 exceeds the throttle opening guard value, the throttle opening guard value that is the upper limit value is output to the throttle 2 as the corrected target TA.

  The throttle opening guard value used in the throttle opening guard 22 is determined by the throttle opening guard value calculation map 24. In the throttle opening guard value calculation map 24, the throttle opening guard value is set according to the boundary value of the dead zone of the throttle opening. The dead zone of the throttle opening is an area where the response of the change in the throttle passage flow is low with respect to the change in the throttle opening. More specifically, the change in the throttle passage flow when the throttle opening changes by a predetermined angle. It means an area where the amount is below a predetermined reference value. As shown in FIG. 2, the size of the dead zone varies depending on the engine speed. FIG. 2 is a graph showing the relationship between the amount of air passing through the throttle per cycle of the internal combustion engine and the throttle opening in a steady state. As shown in this graph, the larger the engine speed, the greater the throttle opening at which the amount of air passing through the throttle reaches the maximum value. That is, the dead zone is larger when the engine speed is smaller, and decreases as the engine speed increases. Based on the relationship between the engine speed and the dead zone, the throttle opening guard value calculation map 24 sets a throttle opening guard value for each of the rotation speed ranges divided into a plurality of ranges.

  In addition to the throttle opening guard value and the target TA, ΔPm input to the intake pipe inverse model 14 is input to the throttle opening guard 22 in parallel. ΔPm is used as information for controlling the operation of the throttle opening guard 22. In addition, the target TA is a target to be guarded by the throttle opening guard 22, and at the same time, is used as information for controlling the operation of the throttle opening guard 22. The operation of the throttle opening guard 22 will be described below based on the flowchart of FIG.

  First, the throttle opening guard 22 acquires a throttle opening guard value corresponding to the current engine speed from the throttle opening guard value calculation map 24 (step S1).

  Next, the throttle opening guard 22 determines whether or not the target TA input from the air inverse model 10 is greater than or equal to a predetermined value (step S2). If the target TA is smaller than the predetermined value, the target TA is not limited by the throttle opening guard value. The predetermined value used in this determination is set to a value lower than the dead zone boundary value.

  If the target TA is greater than or equal to the predetermined value, the throttle opening guard 22 determines whether or not ΔPm is less than or equal to a threshold value (step S3). If ΔPm is equal to or smaller than the threshold value, the throttle opening guard 22 limits the target TA based on the throttle opening guard value acquired in step S1 (step S4). On the other hand, if ΔPm exceeds the threshold value, the throttle opening guard 22 releases the restriction of the target TA by the throttle opening guard value. In this determination, ΔPm is used as a numerical value representing the acceleration state of the internal combustion engine. This is because when the internal combustion engine is accelerated, ΔPm expands due to the difference between the required Pm and the virtual Pm corresponding to the current value of the intake pipe pressure. The threshold used in this determination is set to a magnitude that does not erroneously detect the minute vibration of ΔPm that occurs in the steady operation state.

  By operating the throttle opening guard 22 as described above, according to the present control apparatus, it is possible to obtain a control result as shown in the chart of FIG. FIG. 4 is a time chart showing an operation image during steady-state acceleration / deceleration of the internal combustion engine controlled by the present control device compared with an operation image according to a comparative example. Here, as a comparative example, a device in which the throttle opening guard 22 is removed from the configuration shown in FIG. 1 is used. In the upper chart of FIG. 4, the time change of the opening degree of the accelerator pedal is shown. In the middle chart, the time change of the throttle opening by the present control device is shown by a solid line, and the time change of the throttle opening by the comparative example is shown by a dotted line. In the lower chart, the time variation of the throttle passage air amount per cycle by the present control device is indicated by a solid line, and the time change of the throttle passage air amount by the comparative example is indicated by a dotted line.

  FIG. 4 shows a control result when the accelerator pedal is once depressed and then depressed again, that is, when acceleration is performed after decelerating once. A control result according to a comparative example that does not include the throttle opening guard 22 will be described. According to the comparative example, the throttle opening is always controlled to the target TA calculated by the air inverse model 10. The target TA calculated by the air inverse model 10 is the throttle opening for accurately realizing the required intake air amount. Therefore, when the required intake air amount is large to some extent, the throttle opening according to the comparative example is within the dead zone. become. When an operation for closing the accelerator pedal is performed in this state, the throttle 2 passes through the dead zone and is closed to the final target TA. However, while the throttle 2 is operating in the dead zone, there is almost no change in the intake air amount with respect to the change in the throttle opening. For this reason, a response delay occurs from the time when the throttle 2 starts to close until the amount of air passing through the throttle starts to decrease by the amount of time required to get out of the dead zone.

  On the other hand, according to this control apparatus, the following control results can be obtained. First, when the internal combustion engine is in a steady region, the target TA is guarded by the throttle opening guard 22, so that the throttle is operated outside the dead zone with the throttle opening guard value as an upper limit. Outside the dead zone, it is possible to obtain a change in the intake air amount that exceeds a certain level with respect to a change in the throttle opening. Therefore, according to the present control device, when the driver performs an operation of closing the accelerator pedal and the required intake air amount is reduced by the operation, the throttle 2 can be moved so as to quickly reduce the intake air amount. it can. Compared with the above-described comparative example, according to the present control device, it is possible to eliminate the response delay from when the throttle 2 starts to close until the throttle passage air amount starts to decrease, and accordingly, the internal combustion engine is decelerated more quickly. Can be made.

  Next, when the driver depresses the accelerator pedal, the operating range of the internal combustion engine shifts to the acceleration region, and thus the target TA guard by the throttle opening guard 22 is released. Since the dead zone of the throttle opening disappears during the acceleration transition of the internal combustion engine, there is no inconvenience in releasing the restriction of the target TA by the throttle opening guard value. On the contrary, as in the case of the comparative example, the throttle air 2 can be fully opened to increase the intake air amount to the maximum. After that, when acceleration is finished and the operating range of the internal combustion engine shifts to the steady range again, the target TA is guarded by the throttle opening guard 22 again, so that the throttle opening is prevented from staying in the dead zone. Is done.

  The above is the description of the embodiment of the present invention. According to the above-described embodiment, it is possible to sufficiently bring out the deceleration performance of the internal combustion engine together with the acceleration performance. However, 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, in the above-described embodiment, the case where deceleration is performed by a driver's pedal operation has been described as an example. However, the present invention can also respond to a deceleration request issued from a vehicle control device.

2 throttle 4 required torque conversion map 6 required air amount conversion map 10 air reverse model 12 intake valve reverse model 14 intake pipe reverse model 16 throttle reverse model 20 throttle operation model 22 throttle opening guard 24 throttle opening guard value calculation map 30 Air model 32 Throttle model 34 Intake pipe model 36 Intake valve model

Claims (2)

In a control device for an internal combustion engine that controls a throttle according to a target throttle opening,
A target throttle opening calculating means for calculating a target throttle opening for realizing the required intake air amount using an air inverse model;
Guard value determining means for determining a throttle opening guard value for setting an upper limit on the throttle opening according to the engine speed;
And a guard means for performing a release limitations and restrictions by the throttle opening guard value for the target throttle angle calculated by using the air inverse model,
The air inverse model includes at least a process for calculating a required intake pipe pressure from the required intake air amount, a process for calculating a virtual intake pipe pressure corresponding to a current value of the intake pipe pressure from an actual throttle opening, A process for calculating a differential pressure between the required intake pipe pressure and the virtual intake pipe pressure, and a process for calculating the target throttle opening based on the differential pressure;
The guard means limits the target throttle opening by the throttle opening guard value when the target throttle opening is equal to or greater than a predetermined value and the differential pressure is equal to or less than a threshold value, and the target throttle opening. An internal combustion engine configured to cancel the restriction of the target throttle opening by the throttle opening guard value when the degree is smaller than the predetermined value or the differential pressure is larger than the threshold . Control device.   The guard value determining means includes the throttle zone so that a zone in which the operation of the throttle is limited by the throttle opening guard value includes a dead zone in which the response of the change in the flow rate of the throttle with respect to the change in the throttle opening is low. The control device for an internal combustion engine according to claim 1, wherein an opening guard value is determined.

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