JP2785335B2 - Control device for internal combustion engine for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention relates to a control device for an internal combustion engine for a vehicle, and more particularly, to setting a target engine output shaft torque in accordance with an accelerator operation amount, The present invention relates to a control device for a vehicle internal combustion engine configured to control an intake air amount so as to obtain a control value.

<Conventional Technology> As such a control device for an internal combustion engine for a vehicle, there is the following device as described below.

That is, as a method of controlling the torque characteristic and the output characteristic of the engine with respect to the accelerator operation amount to characteristics preferable for the drivability of the vehicle, for example, as disclosed in Japanese Patent Application Laid-Open No. 60-1922843, There is a device that determines the opening of the throttle valve in accordance with the rotation speed and controls the drive of the throttle valve so as to match the set opening.

<Problems to be Solved by the Invention> However, in such a conventional control device for a vehicle internal combustion engine, there is a case where an accelerator operation is performed such that the torque suddenly changes due to the characteristics of the engine itself. Although it is possible to control the actually generated torque characteristic to a desirable form, the response characteristic of the actual output shaft torque of the engine to the accelerator operation amount can be controlled by the vehicle vibration (abrupt change in torque) in an arbitrary driving range. It was not possible to switch to an arbitrary response characteristic while avoiding it. For this reason, for example, the steady-state characteristic and the transient characteristic of the actual output shaft torque of the engine with respect to the accelerator operation amount are separately controlled, and the torque response characteristic at the transient state is optimally controlled without overshoot, and the torque stability at the steady state is stabilized. However, there is a problem that it is not possible to secure the property.

That is, for example, depending on the driver's preference, it is preferable that the response characteristic of the engine torque to the operation amount of the accelerator pedal is more sensitive (especially during acceleration operation), or if the driver is less sensitive to the accelerator operation amount (particularly, However, in the conventional control device, since the throttle valve opening is uniquely determined by the accelerator operation amount and the engine speed, the response characteristics are switched according to the driver's preference, for example. I couldn't do that.

In addition, the best response level obtained while avoiding vehicle vibration varies depending on the driving region, but in the past, it was not possible to switch the torque response characteristics depending on the driving region. Or unpleasant vehicle vibration occurs in a part of the driving area in order to avoid the problem or secure the response characteristics.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made in consideration of the driver's preference and driving state so that a response characteristic of an actual torque with respect to an accelerator operation amount can be selected from a plurality of reference models. The purpose is to enhance the nature.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. 1, an accelerator operation amount detecting means for detecting an accelerator operation amount, and a target engine output shaft based on the accelerator operation amount detected thereby. Target torque setting means for setting a torque; response characteristic selecting means for selecting a reference model of a response characteristic of the engine output shaft torque with respect to an accelerator operation amount from a plurality of types stored in advance; In order to change the actual engine output shaft torque with response characteristics, the target engine output shaft torque is subjected to phase compensation according to the selected reference model, and the phase compensated target engine output shaft torque is calculated. A phase compensation torque setting means for setting the final command value; and an engine suction shaft for obtaining the engine output shaft torque of the command value set by the phase compensation torque setting means. A control device for an internal combustion engine for a vehicle is configured to include an intake air amount control means for controlling an air input amount.

Here, an engine speed detecting means for detecting the engine speed, a throttle valve opening degree detecting means for detecting the opening of a throttle valve interposed in the engine intake system, the detected engine speed and the throttle An intake air amount response delay time constant setting means for setting a response delay time constant of the intake air amount based on the valve opening degree, wherein the phase compensation torque setting means comprises the selected reference model and the intake air The target engine output shaft torque may be phase-compensated according to the response delay time constant of the quantity.

The apparatus further comprises an actual torque detecting means for detecting an actual engine output shaft torque, wherein the phase compensation torque setting means sets the target engine according to the selected reference model and the detected actual engine output shaft torque. The configuration may be such that phase compensation is performed on the output shaft torque.

Further, an engine rotation speed detecting means for detecting a rotation speed of the engine, a torque response delay time setting means for predicting and setting a response delay time until the engine generates torque based on the detected engine rotation speed, And the phase compensation torque setting means may be configured to perform phase compensation on the target engine output shaft torque according to the selected reference model and the predicted and set response delay time.

<Operation> According to the control device having such a configuration, while a steady target engine output shaft torque is set based on the accelerator operation amount, a reference model of a response characteristic of the engine output shaft torque to the accelerator operation amount is selected. Then, the target engine output shaft torque is phase-compensated so that the actual engine output shaft torque changes in response to the response characteristics of the reference model, and a command value of the phase-compensated engine output shaft torque is obtained. Thus, the intake air amount of the engine is controlled.

Further, when the target engine output shaft torque is subjected to phase compensation so as to follow the response characteristics of the selected reference model, the response delay time constant of the intake air amount, the detected value of the engine output shaft torque, and the engine By using the response delay time before the occurrence, the actual engine output shaft torque that changes in accordance with the response characteristics of the reference model with high accuracy is obtained.

<Examples> Examples of the present invention will be described below.

In FIG. 2 schematically showing the system configuration of the present embodiment, a crank angle sensor 2 as an engine rotation speed detecting means for detecting a crank angle and a rotation speed Ne of the engine 1, and an operation amount (depressed amount) of an accelerator pedal (not shown). a, for example, an accelerator operation amount sensor 3 as an accelerator operation amount detecting means for detecting an output voltage of a potentiometer, and an opening degree θR of a throttle valve 5 provided in an intake passage 4 of the engine 1.
And a reference model selection switch 7 as response characteristic selection means for detecting the opening degree of the throttle valve. A detection signal and a selection signal from these sensors and the switch are supplied to the CPU 8a of the microcomputer 8. To be entered.

Here, the CPU 8a calculates a target output shaft torque (hereinafter, abbreviated as a target torque) of the engine 1 based on the detection signal, calculates a response delay time constant of the intake air amount, and A predetermined reference model is set in accordance with the selection of the switch 7 from among the reference models in the set engine torque response. Then, the actual engine output shaft torque with respect to the accelerator operation amount (hereinafter abbreviated as actual torque).
The target torque is phase-compensated using the time constant so that the response characteristic of the selected reference model matches the response characteristic of the selected reference model, and the engine output shaft torque (hereinafter abbreviated as torque).
Is obtained from the throttle valve opening table 8b, and the servo control circuit 9 outputs the target throttle valve opening which gives the intake air amount necessary for outputting the control value. By controlling the drive of a servo motor 10 via a servo drive circuit 9, the opening of the throttle valve 5 is controlled to control the amount of intake air.

Therefore, in this embodiment, the microcomputer 8
Has a function as target torque setting means, phase compensation torque setting means, intake air amount response delay time constant setting means, and torque response delay time setting means. Further, in the present embodiment, the intake air amount control means includes a servo drive circuit 9, a servomotor 10, and a throttle valve 5.

Further, the microcomputer 8 outputs an ignition signal to the ignition coil 11 based on the crank angle signal output from the crank angle sensor 2 to control the ignition timing by the ignition plug 12 by a known method, and Fuel supply control performed by outputting a fuel injection signal to the injector 13 is simultaneously performed.

The throttle valve opening degree table 8b is provided with a target throttle valve opening degree θo such that an intake air amount necessary for generating the target torque can be obtained if the momentary target torque and the engine speed Ne are given. This is stored on the ROM.

The servo drive circuit 9 is connected to the rotation axis of the throttle valve 5 according to the deviation between the opening θR of the throttle valve 5 detected by the throttle sensor 6 and the target throttle valve opening θo input from the microcomputer 8. The servo motor 10 is driven to rotate forward and reverse so that the opening of the throttle valve 5 follows the target value.

Next, in accordance with the program shown in FIG. 3, each calculation processing such as setting of the target torque, phase compensation of the target torque based on the response delay time constant of the intake air amount, and setting of the target throttle valve opening θo will be described.

The program shown in FIG. 3 is executed at regular intervals, for example, every 10 ms. First, at P1, the operation amount (opening) a of the accelerator pedal detected by the accelerator operation amount sensor 3 is read.

At P2, the engine speed Ne is calculated based on the crank angle signal from the crank angle sensor 1.

At P3, the opening degree θR of the throttle valve 5 detected by the throttle sensor 6 is read.

In P4, the time constant τf of the response delay of the intake air amount is calculated as follows.

Generally, there is a response delay between the amount of air Qs passing through the throttle valve 5 and the amount of air Qcyl actually sucked into the cylinder during the suction stroke. It is known that it is expressed by a first-order lag relationship as in the following equation. In the following equation, s is a Laplace operator (differential operator).

τf [sec] is a response delay time constant of air, which takes a different value depending on the throttle valve opening θR and the engine speed Ne, and the value is obtained by the following equation, for example.

Here, Vc is the collector volume, R is the gas constant, ta is the intake air temperature, Pa is the atmospheric pressure, ηv is the charging efficiency, VE is the engine displacement,
γa is the air density, C is the throttle valve opening constant, and g is a constant determined by the intake pipe pressure.

In P4, the engine speed which is a variable in the above equation
The time constant τf is obtained by table lookup from the table data of the time constant τf obtained in advance corresponding to Ne and the throttle valve opening θR.

In P5, based on the signal from the reference model selection switch 7, the time constant Ta of the reference model (for example, the first-order lag model) of the engine torque response is selected from a plurality of types that are set and stored in advance.

The reference model may be selected automatically based on a driving state such as a vehicle speed or a gear ratio, in addition to manual switching by the selection switch 7.

In P6, the target torque Ter is calculated from the accelerator opening a according to the following equation.

Ter = k1 · a Here, k1 is a constant that defines the magnitude of the convergence value of the torque, and may be switched according to the driver's preference or the traveling environment of the vehicle.

In P7, the target torque Ter calculated in P6 is subjected to model matching phase compensation as given by the following response function Cm (s) to calculate a torque control value Tec.

In practice, the above equation is calculated by the following equation obtained by converting the above equation into a discrete time system with a sample period Tsmp (0.01 sec). However,
(K) shows time series data.

X (k) = kf.X (k-1) + (1-kf) .Y1 (k) Kf = exp (-Tsmp / Ta) In P8, the engine speed Ne calculated in P2 and the calculation in P7 The target throttle valve opening θo is read from the throttle valve opening table 8b based on the torque control value Tec thus obtained.
As shown in FIG. 5, the throttle valve opening degree table 8b
The target throttle valve opening θo is read based on the torque control value Tec and the engine rotation speed Ne. The data of the target throttle valve opening θo is based on the steady performance (the accelerator opening and the engine rotation speed) of the engine 1 mounted on the vehicle. Is a data obtained by plotting the engine torque when is constant.

In P9, the target throttle valve opening θo calculated in P8
Is output to the servo drive circuit 9. As a result, the throttle valve 5 is driven by the servomotor 6 and is feedback-controlled so that the opening θR matches the target throttle valve opening θo.

 Next, the operation of this embodiment will be described with reference to FIG.

The torque that can actually be generated in the engine 1 is substantially proportional to the amount of air Qcyl actually sucked into the engine 1. In the present embodiment, the engine speed Ne and the engine speed Ne are determined based on data determined from the steady performance of the engine 1 mounted on the vehicle (the engine torque is plotted when the accelerator opening and the engine speed are constant). The target throttle valve opening θo is obtained from the torque control value Tec. Therefore, the relationship between the engine torque control value Tec and the actual engine output shaft torque Treal is similar to the relationship between the throttle valve passing air amount Qs and the cylinder intake air amount Qcyl,
It is expressed by the following equation using the response delay time constant τf of the intake air. Here, τP is a response delay time required for the engine 1 to generate torque.

In this embodiment, the actual torque Tr with respect to the accelerator operation amount a
In order to match the response characteristic of eal with an arbitrary reference model selected by the reference model selection switch 7, phase compensation for model matching as shown in the following equation is performed as described above.

Accordingly, the response characteristic of the actual torque Treal with respect to the accelerator operation amount a due to the pole-zero cancellation is expressed by the following equation.

Here, it can be seen that the response characteristic of the actual torque Treal can be freely changed by switching the steady-state gain k1 or the time constant Ta of the reference model depending on the situation.

Therefore, the time constant Ta of the reference model switched and set by the reference model selection switch 7 is, for example, two types corresponding to a sporty mode having a relatively small time constant Ta and a normal mode having a relatively large time constant Ta. When it is desired to obtain a quick response of the engine torque to the accelerator operation amount a, the switch 7 is switched to the sporty side to obtain a more responsive engine torque response than at the time of the normal selection and to exhibit agile power performance. On the other hand, when the engine torque does not respond to the slight accelerator operation amount a, the normal operation is selected by the switch 7.
The responsiveness of torque generation can be selected according to the driver's preference.

In the setting of the reference model, if the level of responsiveness at which unpleasant vehicle vibration occurs is not set in advance, even if a more responsive model is selected,
Good drivability can be ensured without accompanying vehicle vibration (rapid change in torque).

Further, in this embodiment, the response delay time constant τf of the intake air amount used for matching the actual response to the reference model is sequentially switched and set according to the engine speed Ne and the throttle valve opening θR. Therefore, it is possible to more accurately match the actual response to the reference model.

Next, a description will be given of a second embodiment in which the actual torque is detected by a sensor and the actual torque is feedback-controlled to the target torque.

In the first embodiment, the response delay time constant τ of the intake air amount is
The phase compensation for the model matching is performed based on f. In the second embodiment described below, the actual torque of the engine 1 is detected, and the response delay until the engine 1 actually generates the torque is detected. The time is estimated, and the response delay time constant τf of the intake air amount used in the first embodiment is used, and phase compensation for model matching is performed based on these. Therefore, in this embodiment, a torque sensor 14 as an actual torque detecting means for detecting the actual torque Treal of the engine 1 is additionally provided in the system configuration shown in FIG.

FIG. 6 shows a program showing the arithmetic processing according to the second embodiment. Since P1 to P5 and P8 are the same as the program shown in FIG. 3 described in the first embodiment, Only P6, P7, P9 different from the program of FIG. 3 will be described.

At P6, the actual torque Treal of the engine 1 detected by the torque sensor 14 is read.

At P7, a response delay time until the engine 1 actually generates torque is calculated using the calculated engine speed Ne. For example, in a four-cycle internal combustion engine, the time required for the intake and compression strokes remains at least as a response delay time until torque is generated. Time τP (= 60 / Ne).

At P9, the target torque Ter calculated at P8, the actual torque Treal detected at P6, the response delay time constant τf of the intake air amount calculated at P4, and the torque generation response delay time of the engine 1 calculated at P7 Reference model time constant selected at τP and P5
The control value Tec of the engine torque is calculated using Ta. In this embodiment, the engine torque is controlled by a feedback control system using a configuration of a known control method (see FIG. 7).

Here, the target torque Ter (s) and the actual torque Treal
The relationship between (s) and the engine torque control value Tec (s) is shown in the following equation.

Tec (s) = Cm (s) · [Ter (s) − ｛Treal (s) −G (s) ·
Tec (s)｝] where G (s) is the difference between the engine torque control value Tec and the actual torque Treal obtained from the response delay time constant τf of the intake air amount and the response delay time τP of the torque generation as described above. Institutional model showing the relationship ΔG (s) = Treal (s) / Tec
(S)｝ and Cm (s) are phase compensators for model matching.

In practice, the above equation is calculated by the following equation, which is converted into a discrete time system at a sample cycle Tsmp (0.01 sec), which is the execution cycle of this program.

X (k) = kf.X (k-1) + (1-kf) .Y1 (k) Y1 (k) = Ter (k)-{Treal (k) -Y2 (k-.tau.P / Tsmp)} Y2 (k) = kp · Y2 (k−1) + (1−kp) · Tec (k−1) kf = exp (−Tsmp / Ta) kp = exp (−Tsmp / τf) In this embodiment, the torque sensor is used. Actual torque Tr detected at
eal and the response delay time τP of the engine torque calculated from the engine speed Ne are used for matching to match the actual characteristics to the response characteristics of the reference model. The response characteristic of the actual torque with respect to the operation amount can be accurately matched with the selected reference model.

In the above two embodiments, the response characteristics of the output shaft torque of the engine are matched with the reference model. However, such as manual transmission and CVT (continuously variable transmission; continuously variable transmission), etc. When the speed change mechanism is connected to the engine, control for matching the response characteristic of the drive wheel output torque to the reference model can be performed by detecting the speed ratio of the speed change mechanism as in the above-described embodiment.

In order to perform the phase compensation of the target torque, there are various response delays peculiar to the engine. Therefore, in the above embodiment, the response delay time constant of the intake air amount is used, or the response delay time constant and the torque generation response delay time are used. And the feedback by the actual torque detection to perform the phase compensation.
Phase compensation using the response delay time constant of the intake air amount, the response delay time of torque generation, and the actual torque alone,
It is also possible to use two of the three in combination for phase compensation. However, especially in an engine with a large collector volume, the response delay of the intake air amount becomes large,
It is preferable to use a response delay time constant of the intake air amount.

<Effects of the Invention> As described above, according to the present invention, the target engine output shaft torque set based on the accelerator operation amount so that the actual engine output shaft torque changes with the response characteristic of the selected reference model. By applying phase compensation to
Any desired reference model can be selected so that the response characteristic of the actual torque with respect to the accelerator operation amount can be made to match this reference model, and the driving characteristic of the vehicle is switched by switching to a preferable response characteristic according to the driver's preference or driving state. Can be enhanced.

In addition, when performing phase compensation to match the above-described reference model, the response delay time constant of the intake air amount, the actual engine output shaft torque, and the torque generation response delay time may be involved alone or in combination. Thus, the engine torque can be changed in accordance with the reference model accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system schematic diagram showing a system configuration of an embodiment of the present invention, and FIG.
FIG. 4 is a flowchart showing the control contents in the first embodiment of the present invention. FIG. 4 is a functional explanatory block diagram for explaining control characteristics in the first embodiment. FIG. 5 is a diagram showing the target throttle valve opening degree in the first embodiment. FIG. 6 is a diagram showing an example of a setting state, FIG. 6 is a flowchart showing control contents in a second embodiment of the present invention, and FIG. 7 is a functional explanatory block diagram for explaining control characteristics in the above embodiment. 1 ... engine 2 ... crank angle sensor 3 ... accelerator opening sensor 5 ... throttle valve 6 ... throttle sensor 7 ... standard model selection switch 8 ... microcomputer 8a ... CPU , 8b ... throttle valve opening table, 9 ... servo drive circuit, 10 ... servo motor,
14 ... Torque sensor

Claims (4)

(57) [Claims] 1. An accelerator operation amount detecting means for detecting an accelerator operation amount; a target torque setting means for setting a target engine output shaft torque based on the detected accelerator operation amount; and an engine output shaft torque corresponding to the accelerator operation amount. Response characteristic selecting means for selecting a reference model of the response characteristic from a plurality of types stored in advance, and the target engine output to change the actual engine output shaft torque with the response characteristic of the selected reference model. Phase compensation torque setting means for performing phase compensation on the shaft torque in accordance with the selected reference model, and setting the target engine output shaft torque subjected to the phase compensation as a final command value; Intake air amount control means for controlling the intake air amount of the engine to obtain the engine output shaft torque of the command value set by the torque setting means. Control apparatus for an internal combustion engine for a vehicle according to claim. 2. An engine speed detecting means for detecting an engine speed, a throttle valve opening detecting means for detecting an opening of a throttle valve interposed in an engine intake system, and the detected engine speed. And an intake air amount response delay time constant setting means for setting a response delay time constant of the intake air amount based on the throttle valve opening and the throttle valve opening degree, wherein the phase compensation torque setting means comprises: 2. The control device for an internal combustion engine for a vehicle according to claim 1, wherein a phase compensation is performed on the target engine output shaft torque according to a response delay time constant of the intake air amount. 3. An apparatus according to claim 1, further comprising an actual torque detecting means for detecting an actual engine output shaft torque, wherein said phase compensation torque setting means is configured to output the actual engine output shaft torque in accordance with the selected reference model and the detected actual engine output shaft torque. 3. The control device for an internal combustion engine for a vehicle according to claim 1, wherein a phase compensation is performed on the target engine output shaft torque. 4. An engine speed detecting means for detecting the engine speed, and a torque response time setting for predicting and setting a response time until the engine generates torque based on the detected engine speed. Means, wherein the phase compensation torque setting means is configured to perform phase compensation on the target engine output shaft torque according to the selected reference model and the predicted and set response delay time. The control device for an internal combustion engine for a vehicle according to any one of claims 1 to 3, wherein