JP4539846B2 - Output control device for internal combustion engine - Google Patents

Description

  The present invention relates to an output control device for an internal combustion engine, and more particularly to a technique for reducing vibration (acceleration / deceleration shock) during accelerator operation of a vehicle.

  Generally, vibration (acceleration / deceleration shock) occurs when the accelerator of the vehicle is depressed or returned (particularly when the accelerator is depressed suddenly). Such acceleration / deceleration shock is caused by a sudden change in engine torque due to a sudden accelerator depression or return operation, resulting in torsional vibration in the drive system. And the torsional vibration of the drive system appears as a vibration phenomenon in the longitudinal direction of the vehicle body.

A method of slowly opening the throttle is widely known in order to suppress the vibration of the drive system that occurs due to such an accelerator operation. However, such a method impairs the feeling of acceleration.
For this reason, the applicant of the present application has installed a compensator upstream of the control input of the electronic throttle valve (ETV), and in view of the fact that the generated torque is largely controlled by the intake air amount, the engine torque is throttled. A method of controlling the vibration of the drive system by controlling it as a time-series profile of the opening degree has been proposed (Patent Document 1, etc.).
JP 2004-68702 A

However, in the technique disclosed in Patent Document 1, a good compensation effect can be obtained in a region where the throttle opening is low as in normal driving, while a high opening as in a transient during sudden acceleration. In such a region, it was confirmed that a sufficient compensation effect could not be obtained, and the response was poor and the torque waveform was disturbed.
This is not a steady state in which the intake pipe pressure is determined by the throttle opening and the engine speed during the transition, but an inrush amount of air is used to open the throttle from a low intake pipe pressure. This is probably because the intake pipe pressure rapidly increases after passing through the throttle, and the relationship between the amount of air passing through the throttle and the amount of cylinder intake air changes.

That is, it is considered that even if the throttle is greatly opened, the target intake air amount based on the throttle opening is not sucked into the cylinder.
The present invention has been made to solve such a problem, and an object of the present invention is to improve the responsiveness in a transient state and to accurately realize a time-series torque waveform. It is to provide an engine output control device.

In order to achieve the above object, in the output control apparatus for an internal combustion engine according to claim 1, an accelerator opening degree detecting means for detecting an accelerator opening degree and a target based on the accelerator opening degree detected by the accelerator opening degree detecting means. A target throttle opening calculating means for setting a torque, obtaining a target intake air amount from the target torque and calculating a target throttle opening based on the target intake air amount; and a target calculated by the target throttle opening calculating means A throttle opening adjusting means for adjusting the throttle opening based on the throttle opening; and an intake pipe pressure detecting means for detecting an intake pipe pressure on the downstream side of the throttle, the target throttle opening calculating means, Furthermore, depending on the pressure ratio between the atmospheric pressure on the upstream side of the the detected intake pipe pressure throttle by the intake pipe pressure detecting means Circle and corrects the target throttle opening based on the flow rate ratio of the amount of intake air to the combustion chamber of the throttle passage air quantity and the engine.

That is, the target torque is set based on the accelerator opening, and the target throttle opening is calculated by obtaining the target intake air amount from the target torque. At this time, the target throttle opening is calculated by the intake pipe pressure detecting means. Based on the flow rate ratio between the amount of air passing through the throttle and the amount of intake air into the combustion chamber of the internal combustion engine, which is determined according to the pressure ratio between the intake pipe pressure detected by the air pressure and the atmospheric pressure upstream of the throttle, It is corrected appropriately according to.

  The output control apparatus for an internal combustion engine according to claim 2, wherein the flow rate ratio is constant when the pressure ratio is equal to or lower than a predetermined critical pressure ratio, and the throttle ratio is increased as the pressure ratio becomes larger than the predetermined critical pressure ratio. The target throttle opening calculation means is configured to divide the target intake air amount by the flow rate ratio, so that the intake air amount to the combustion chamber of the internal combustion engine becomes smaller with respect to the passing air amount. Thus, the target throttle opening is calculated.

  In other words, the flow rate ratio between the amount of air passing through the throttle and the amount of intake air into the combustion chamber of the internal combustion engine is constant when the pressure ratio is less than or equal to a predetermined critical pressure ratio, and as the pressure ratio becomes larger than the predetermined critical pressure ratio, It has a certain characteristic that the amount of intake air into the combustion chamber of the internal combustion engine decreases with respect to the amount of air passing through. From this, it is easy to divide the target intake air amount by the flow rate ratio and calculate backward. Thus, the target throttle opening is properly calculated.

According to the output control apparatus for an internal combustion engine of claim 1 , based on the flow rate ratio between the amount of air passing through the throttle and the amount of intake air into the combustion chamber of the internal combustion engine, which is determined according to the pressure ratio between the intake pipe pressure and the atmospheric pressure. Because the target throttle opening is corrected , the target throttle opening can be calculated appropriately according to the actual situation, and the responsiveness can be improved during transients such as during sudden acceleration. The torque waveform can be realized accurately.

  According to the output control device for an internal combustion engine of claim 2, the flow rate ratio between the amount of air passing through the throttle and the amount of intake air into the combustion chamber of the internal combustion engine is constant when the pressure ratio is equal to or less than a predetermined critical pressure ratio, It has a certain characteristic that the amount of intake air into the combustion chamber of the internal combustion engine decreases with respect to the amount of air passing through the throttle as it becomes larger than the predetermined critical pressure ratio, and the target intake air amount is obtained from the characteristic. By dividing by the flow rate ratio and calculating backward, the target throttle opening can be calculated appropriately with ease.

Hereinafter, an embodiment of an output control device for an internal combustion engine according to the present invention will be described with reference to the drawings.
Referring to FIG. 1, a configuration of an intake system of an internal combustion engine (an intake pipe injection type gasoline engine, hereinafter referred to as an engine) 1 according to the present invention is schematically shown. As shown in FIG. The pipe 2 is provided with a so-called electronic throttle valve (throttle opening adjusting means) 3 in which an accelerator pedal and a throttle valve are electrically connected. The throttle valve 3 has a throttle opening sensor (TPS), and an intake manifold 4 on the intake downstream side of the throttle valve 3 has a manifold pressure sensor (intake pipe pressure detecting means) for detecting an intake manifold pressure, that is, an intake pipe pressure Pm. ) 5 is provided. In the figure, Qt represents the amount of air passing through the throttle valve 3, Qc represents the amount of intake air to the cylinder (combustion chamber) of the engine 1, and Pa represents the atmospheric pressure upstream of the throttle valve 3. The other configurations of the engine 1, for example, the intake valve 6, the exhaust valve 7, the injector 8, the spark plug 9, the cylinder 1a, and the like are well known and will not be described here.

Referring to FIG. 2, a control model of a system including an output control device according to the present invention is shown in a block diagram.
According to the block diagram, in the control model, the accelerator opening signal from the accelerator opening sensor (APS, accelerator opening detecting means) 10 for detecting the amount of operation of the accelerator pedal, that is, the accelerator opening is an ECU (electronic control). To the controller 20 that is part of the unit. In the controller 20, the accelerator opening signal is converted into a throttle opening signal, and the throttle opening signal is input from the controller 20 to the engine model 30. In the engine model 30, the throttle opening signal is converted into a torque signal, the torque signal is input from the engine model 30 to the vehicle model 40, and the vehicle model 40 is output-controlled based on the torque signal.

Referring to FIG. 3, a block diagram of the controller 20 is shown, and the control contents of the controller 20 will be described below with reference to FIG.
When the accelerator opening signal is input to the controller 20, the target torque is set in the target torque setting unit 50 based on the target accelerator opening signal. The target torque signal is converted into a target intake air amount based on a torque-air amount map using the engine speed Ne set in advance in the torque air amount conversion unit 52 as a parameter. Then, the target intake air amount signal is input to the predistorter 54.

In the pre-compensator 54, the time constant of the intake pipe is corrected. Here, although the transfer function is represented by (1 + Ts) / (1 + T ₁ s), (s ² + 2ξω _n s + ω _n ² ) / (s ² + 2ξ′ω _n s + ω _n ² ) is used as the vibration suppression type transfer function. You may make it use. Here, s is a Laplace operator, and ω _n , ξ, and ξ ′ are a resonance frequency and a damping coefficient of the system, respectively.
Since the time constant of the first-order lag is determined by the intake pipe volume and the engine speed Ne, this may be corrected.

The target intake air amount signal an whose time constant has been corrected through the pre-compensator 54 is input to a feedforward controller (FF controller) 56, and the FF controller 56 uses the target intake air amount signal an based on the target intake air amount signal an. The throttle opening θt is calculated, and a target throttle opening signal θt is output (target throttle opening calculation means).
Referring to FIG. 4, a block diagram of the FF controller 56 according to the present invention is shown, and the control contents of the FF controller 56 according to the present invention will be described below based on the same diagram.

Since the target intake air amount signal an is normally the unit intake air amount per one rotation of the engine, the conversion unit 70 converts the unit intake air amount into the intake air amount per time. Then, the idle / dashpot flow rate Q0 is added to the intake air amount per hour to obtain the target intake air amount Q per hour (Q = an · Ne / 60 + Q0).
Referring to FIG. 5, the ratio between the intake pipe pressure Pm on the downstream side of the throttle valve 3 detected by the manifold pressure sensor 5 and the atmospheric pressure Pa on the upstream side of the throttle valve 3, that is, the intake pipe pressure Pm is the atmospheric pressure Pa. According to the flow coefficient φ, ie, the intake pipe pressure, which is the flow ratio between the amount of air Qt passing through the throttle valve 3 determined according to the divided pressure ratio Pr (= Pm / Pa) and the amount of intake air Qc into the cylinder of the engine 1 The flow characteristics are shown. According to the flow rate characteristic, when the pressure ratio Pr is equal to or less than the critical pressure ratio (0.53) (Pr ≦ 0.53), the flow coefficient φ is constant in the vicinity of the value 0.7, but within a range larger than the critical pressure ratio ( In 0.53 <Pr ≦ 1.0), the larger the pressure ratio Pr, the smaller the flow coefficient φ.

  Referring to FIG. 6, the relationship between the amount of air Qt (solid line) passing through the throttle valve 3 and the amount of intake air Qc (dashed line) to the cylinder is that the throttle opening is low (Qt1, Qc1). Although it is shown in the time chart in comparison with the case of high opening (Qt2, Qc2), as shown in the figure, the opening of the throttle valve 3, that is, the throttle opening θ is kept high. If held, the amount of air Qt2 passing through the throttle valve 3 suddenly increases, so that the intake pipe pressure Pm approaches the atmospheric pressure Pa. Thereafter, when the pressure ratio Pr exceeds the critical pressure ratio, the intake pipe pressure Pm and the atmospheric pressure Pa. The pressure difference gradually decreases and the amount of intake air Qc2 to the cylinder decreases.

For this reason, when the flow rate coefficient φ is larger than the predetermined value ε in the switching unit 74 and switched to the Y side, the target intake air amount signal Q is a coefficient 1 based on the shape in the conversion unit 72. After being multiplied by / K, the value is input to the target throttle opening calculation unit 76 via the switching unit 74.
Then, the target throttle opening calculation unit 76 calculates the target throttle opening θt from the following equations (1) and (2) by back calculation based on the target intake air amount Q.

A = Q / (K · φ) (1)
θt = cos ⁻¹ (1-A / A0) (2)
Here, A is the required throttle opening area, and A0 is the fully open throttle opening area.
That is, here, as shown in FIG. 5, the target throttle opening degree θt is obtained in consideration of the flow coefficient φ that changes according to the pressure ratio Pr between the intake pipe pressure Pm and the atmospheric pressure Pa upstream of the throttle valve 3. Like that.

When the flow rate coefficient φ is not more than the predetermined value ε and is switched to the N side in the switching unit 74, the target throttle opening degree θt is set to the fully open θwt.
When the target throttle opening θt is thus obtained, the target throttle opening signal θt is input to the throttle mechanism 60, that is, the throttle valve 3 via the throttle controller 58 of FIG. Thus, the throttle valve 3 is appropriately controlled based on the target throttle opening signal θt.

The actual throttle opening θ of the throttle valve 3 is input as the throttle opening signal θ into the engine model 30 of FIG. 2 and converted into the intake air amount Qc into the cylinder of the engine 1 and then converted into the engine torque. The The throttle opening θ is fed back to the throttle controller 58.
Further, the target throttle opening degree θt is feedback-controlled based on the intake air amount Qc to the cylinder of the engine 1. Specifically, the intake air amount Qc is multiplied by a coefficient K, and then input to a feedback controller (FB controller) 62, which is feedback-controlled by the FB controller 62. PID control is employed as the feedback control, but integral control may be used as long as steady target tracking is performed, and differential control may be performed as long as transient tracking is mainly performed.

  As described above, according to the output control apparatus for an internal combustion engine according to the present invention, the ratio between the intake pipe pressure Pm downstream of the throttle valve 3 and the atmospheric pressure Pa upstream of the throttle valve 3, that is, the intake pipe pressure Pm is set. A flow coefficient (flow ratio) φ between the amount of air Qt passing through the throttle valve 3 determined according to the pressure ratio Pr divided by the atmospheric pressure Pa and the amount of intake air Qc into the cylinder of the engine 1, that is, the intake pipe pressure shown in FIG. The target throttle opening degree θt is obtained in consideration of the flow characteristic according to the above. Specifically, the target throttle opening θt is obtained by dividing the target intake air amount Q by the flow coefficient φ and calculating backward (see the above formulas (1) and (2)).

Therefore, according to the output control device, it is possible to easily calculate the target throttle opening degree θt appropriately in accordance with the actual situation. Thereby, it is possible to improve the responsiveness at the time of transition such as at the time of sudden acceleration, and it is possible to accurately realize a time-series torque waveform.
Although the description of the embodiment of the output control device for an internal combustion engine according to the present invention has been completed above, the embodiment is not limited to the above, and various modifications can be made without departing from the gist of the present invention.

It is a figure which shows typically the structure of the intake system of the internal combustion engine which concerns on this invention. It is a block diagram which shows the control model of the system containing the output control apparatus which concerns on this invention. FIG. 3 is a block diagram of the controller of FIG. 2. FIG. 4 is a block diagram of the FF controller according to the present invention of FIG. 3. The flow rate coefficient φ, which is the flow rate ratio between the amount of air passing through the throttle valve Qt and the amount of intake air Qc determined according to the pressure ratio Pr (= Pm / Pa) between the intake pipe pressure Pm and the atmospheric pressure Pa, that is, the intake pipe pressure It is a figure which shows the flow characteristic according to. It is a time chart which shows the relationship between the passing air amount Qt (solid line) and the intake air amount Qc (broken line) of a throttle valve.

Explanation of symbols

1 Engine 3 Throttle valve (Throttle opening adjustment means)
5 Manifold pressure sensor (intake pipe pressure detection means)
10 Accelerator position sensor (APS, accelerator position detector)
20 controller 30 engine model 40 vehicle model 50 target torque setting unit (target throttle opening calculation means)
52 Torque air amount conversion unit (target throttle opening calculation means)
54 Precompensator (Target throttle opening calculation means)
56 FF controller (target throttle opening calculation means)
62 FB controller 76 Throttle opening calculator

Claims (2)

An accelerator opening detecting means for detecting the accelerator opening;
A target throttle opening that sets a target torque based on the accelerator opening detected by the accelerator opening detecting means, calculates a target intake air amount from the target torque, and calculates a target throttle opening based on the target intake air amount A calculation means;
Throttle opening adjusting means for adjusting the throttle opening based on the target throttle opening calculated by the target throttle opening calculating means ;
An intake pipe pressure detecting means for detecting an intake pipe pressure downstream of the throttle ,
The target throttle opening degree calculation means further includes a passage air quantity of the throttle determined according to the pressure ratio between the atmospheric pressure on the upstream side of the the detected intake pipe pressure throttle by the intake pipe pressure detecting means An output control device for an internal combustion engine, wherein the target throttle opening is corrected based on a flow rate ratio with an intake air amount into a combustion chamber of the internal combustion engine. The flow rate ratio is constant when the pressure ratio is equal to or lower than a predetermined critical pressure ratio, and the intake air amount into the combustion chamber of the internal combustion engine with respect to the amount of air passing through the throttle as the pressure ratio becomes larger than the predetermined critical pressure ratio Change so that
2. The output control apparatus for an internal combustion engine according to claim 1, wherein the target throttle opening calculation means calculates the target throttle opening by dividing the target intake air amount by the flow rate ratio.

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