JP3357089B2 - Engine boost pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging pressure control device for an engine which performs feedback control of a supercharging pressure so as to follow a target supercharging pressure.

[0002]

2. Description of the Related Art Filling efficiency (engine output) by installing a supercharger
Engines with a supercharger designed to increase the pressure have been known. As such a supercharger, generally, a turbine disposed in an exhaust passage drives a blower (pump) disposed in an intake passage to rotate, and pressurizes air by the blower (supercharging). Exhaust turbochargers designed to be used are frequently used. However, this is because the turbocharger of the exhaust type has advantages in that the structure is simple and no shaft power loss occurs in the engine.

The turbocharger having the characteristic that the discharge pressure (supercharging pressure) of the blower becomes high when the energy of the exhaust gas is large, that is, at the time of high rotation or high load, is merely an exhaust gas turbocharger. If the supercharging is performed by relying on the above energy, an appropriate supercharging pressure according to the operating state of the engine cannot be obtained. Therefore, a bypass exhaust passage that bypasses the turbine and a wastegate valve that opens and closes the bypass exhaust passage are provided, and the opening degree of the wastegate valve is adjusted to set the supercharging pressure in accordance with the operation state. An engine with a supercharger adapted to follow a target supercharging pressure has been proposed (for example, see Japanese Patent Application Laid-Open No. Sho 57-14623).

Further, there has been proposed a supercharged engine in which the supercharging pressure is feedback-controlled so that the supercharging pressure follows the target supercharging pressure. In the engine in which the supercharging pressure is feedback-controlled as described above, the target supercharging pressure is generally set higher as the throttle opening (engine load) is larger. Therefore,
When accelerating, that is, when the throttle opening sharply increases, the target supercharging pressure sharply increases accordingly.

However, in the feedback control of the supercharging pressure, generally, after the deviation of the supercharging pressure from the target supercharging pressure is actually detected, the opening of the wastegate valve is adjusted so as to cancel the deviation. Therefore, the change of the supercharging pressure is considerably delayed with respect to the change of the target supercharging pressure. For this reason, the conventional engine in which the supercharging pressure is feedback-controlled has a problem that the acceleration response is deteriorated. In the conventional engine with a supercharger disclosed in Japanese Patent Application Laid-Open No. Sho 57-146023, the target supercharging pressure is increased at the time of acceleration to increase the acceleration responsiveness. Although the response is improved, the supercharging pressure is increased more than necessary.

In general, in the feedback control of the supercharging pressure, an integrating operation is performed. However, during acceleration, the target supercharging pressure rises rapidly, while following the supercharging pressure is delayed. Very large. Therefore, in an attempt to cancel the integral amount of the deviation, the boost pressure continues to increase even after the target boost pressure is reached, and a phenomenon that the boost pressure greatly exceeds the target boost pressure, a so-called overshoot, occurs. There is a problem.

[0007]

Therefore, during acceleration, the feedback control is temporarily stopped, and then the opening degree of the waste gate valve is changed in a stepwise manner by a predetermined amount to rapidly increase the supercharging pressure. A supercharger that prevents an increase in the integral amount of the deviation and then resumes the feedback control from the point in time when the supercharging pressure reaches a boundary supercharging pressure set slightly lower than the target supercharging pressure. Engines have been proposed. In such an engine, for example, FIG.
As shown in ( ₂ ), during acceleration, the throttle opening (H ₁ ) increases in a substantially step-like manner, and accordingly, the target supercharging pressure (H ₂ ) sharply increases in a substantially step-like manner. Then, the feedback control in time theta ₁ is stopped (H _5), so that a predetermined acceleration correction is performed (H _6). Here, if the acceleration correction amount is correct, boost pressure quickly rises as shown by curve H _3, the feedback control reaches the boundary supercharging pressure at time θ ₂ (H ₄₎ is restarted, Shortly thereafter, it will be equal to the target boost pressure (H ₂ ).

Here, if the acceleration correction amount is too large, overshoot occurs as shown by the curve H ₃ ′.
Therefore, in order to prevent the occurrence of such overshoot, the acceleration correction amount is usually set to a minimum. However, since there is some variation in the discharge performance of each supercharger, the supercharger reaches the boundary supercharge pressure (H ₄ ) as shown by the curve H ₃ ″ in the supercharger having a low discharge pressure. Therefore, the feedback control may not be restarted, and in such a case, the acceleration is performed in a state where the supercharging pressure is low, and there is a problem that the traveling performance of the vehicle is deteriorated. A supercharging pressure control device for an engine, which has been made to solve the problem, and is capable of causing a supercharging pressure to quickly and reliably follow a target supercharging pressure without causing overshoot during acceleration. The purpose is to provide.

[0009]

In order to achieve the above object, the first aspect of the present invention, as shown in FIG. 1, is designed to follow a target supercharging pressure set according to the operating state of the engine CE. Supercharge pressure feedback control means a for feedback-controlling the supply pressure, acceleration detection means b for detecting the acceleration state of the engine CE, and the engine CE
Pressure correction means c for correcting the supercharging pressure to a high pressure side when it is detected that the supercharging is in an accelerating state, and a predetermined boundary supercharging in which the supercharging pressure is set slightly lower than the target supercharging pressure. Feedback limiting means for causing the supercharging pressure feedback control means a to perform feedback control only when the pressure is exceeded
In the supercharging pressure control device of the engine provided with d,
After the supercharging pressure is corrected to the high pressure side by the supercharging pressure correcting means c during acceleration, when the supercharging pressure is stabilized at a pressure lower than the boundary supercharging pressure, the supercharging pressure is again corrected to the high pressure side. The present invention also provides a supercharging pressure control device for an engine, wherein a supercharging pressure correction means e is provided.

According to a second aspect of the present invention, in the supercharging pressure control device for an engine according to the first aspect, an acceleration feedback inhibiting means f for inhibiting the feedback control of the supercharging pressure during acceleration is provided. The present invention provides a supercharging pressure control device for an engine.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below.
As shown in FIG. 2, when the intake valve 1 is opened, the engine CE draws an air-fuel mixture into the combustion chamber 3 from the intake port 2, compresses the air-fuel mixture with the piston 4, and ignites with the spark plug 5. Repeating the process of burning and discharging the combustion gas to the exhaust port 7 when the exhaust valve 6 is opened,
The reciprocating motion of the piston 4 in the direction of the cylinder axis caused by this is converted into a rotational motion by a connecting rod 8, a crankpin 9, and a crank arm (not shown) and output to the crankshaft 10. The ignition plug 5 is supplied with a high voltage for spark discharge at a predetermined timing from the ignition coil 11.

An intake device A is provided for supplying air to the engine CE (combustion chamber 3). The intake device A is provided with an intake passage 13 whose downstream end communicates with the intake port 2. The intake passage 13 has an air cleaner 14 for removing airborne dust in the intake air, an air flow meter 15 for detecting the amount of intake air, and an exhaust turbo-type filter which will be described later. A blower 16a (pump) of a feeder 16, an intercooler 17 for cooling pressurized air whose temperature has increased, a throttle valve 18 opened / closed in response to a depression operation of an accelerator pedal (not shown), A fuel injection valve 19 for injecting fuel into the air in the passage 13 is provided.

Further, the combustion gas (exhaust gas) of the engine CE
An exhaust device B is provided for discharging the exhaust gas. The exhaust device B has an exhaust passage 22 having an upstream end communicating with the exhaust port 7.
Is provided. The exhaust passage 22 is provided with a turbine 16b of the supercharger 16 and a catalytic converter 23 using a three-way catalyst in order from the upstream side in the exhaust gas flow direction.

In the turbocharger 16 of the exhaust type, a turbine 16b is driven to rotate by exhaust gas accompanied by exhaust pressure, and the driving force of the turbine 16b is transmitted to a blower 16a via a shaft 16c. The air in the intake passage 13 is pressurized (supercharged). In order to control the discharge pressure of the supercharger 16, that is, the supercharging pressure, a bypass exhaust passage 24 that bypasses the turbine 16b and discharges exhaust gas, and a bypass exhaust passage 24
And a waste gate valve 25 that opens and closes. Here, when the waste gate valve 25 is opened, a part of the exhaust gas is discharged through the bypass exhaust passage 24 bypassing the turbine 16b, and the supercharging pressure is reduced. Therefore, the supercharging pressure can be controlled by adjusting the opening of the waste gate valve 25.

In order to open and close the waste gate valve 25, an actuator 26 comprising a positive pressure responsive diaphragm device is provided. The actuator 26 fully closes the waste gate valve 25 when atmospheric pressure is introduced into the pressure chamber 26a,
When the positive pressure is introduced into the waste gas, the waste gate valve 25 is opened according to the pressure. here,
The pressurized air in the intake passage 13a downstream of the blower 16a is introduced into the pressure chamber 26a through the positive pressure introduction passage 27.

A release passage 28 having one end opening to the intake passage 13b upstream of the blower 16a and the other end opening to the positive pressure introduction passage 27 is provided. The supercharging pressure control valve 29 is interposed. The supercharging pressure control valve 29 is opened and closed according to a supercharging pressure control signal (final duty ratio) applied from the control unit 20. Here, as the opening degree of the supercharging pressure control valve 29 increases, the positive pressure in the pressure chamber 26a is released to the intake passage 13b through the release passage 28, so that the opening degree of the waste gate valve 25 decreases, and The pressure increases.

The intake manifold boost in the intake passage 13a downstream of the blower 16a, ie, the supercharging pressure, basically follows the target supercharging pressure set by the control unit 20 in accordance with the operating state of the engine CE. Feedback control is performed. Further, at the time of acceleration or the like, while the feedback control is stopped by the control unit 20, the acceleration correction of the supercharging pressure is performed, and without causing overshoot,
The supercharging pressure is made to quickly and surely follow the target supercharging pressure. The control unit 20 includes a “supercharging pressure feedback control unit”, an “acceleration detecting unit”, a “supercharging pressure correcting unit”, a “feedback limiting unit”, and a “second supercharging unit”. This is a comprehensive control device for the engine CE or the supercharger 16 including a "supply pressure correcting means" and a "feedback prohibiting means during acceleration". And
The control unit 20 uses, as control information, an intake air amount detected by the air flow meter 15, an intake manifold boost detected by the boost sensor 31, ie, a supercharging pressure, an engine speed detected by the speed sensor 32, a throttle opening, and the like. Although various kinds of predetermined controls are performed, only the supercharging pressure control which is the gist of the present invention will be described below. Hereinafter, the control method of the supercharging pressure control by the control unit 20 will be described with reference to the flowchart shown in FIG.

When the control is started, in step # 1, various data such as the engine speed, the intake manifold boost (supercharging pressure), the throttle opening, and the intake air amount are read as control information. Next, in step # 2, the target boost pressure P0 is calculated. The target supercharging pressure P0 is basically set according to the throttle opening, that is, the engine load, so as to obtain predetermined engine output characteristics.

In step # 3, a base duty ratio to be applied to the boost pressure control valve 29 is calculated according to the target boost pressure P0. In this embodiment, basically, first, a basic base duty ratio is set according to the target supercharging pressure P0, while the deviation (P0−PN) of the actual supercharging pressure PN with respect to the target supercharging pressure P0 is set. Accordingly, a feedback correction amount set to eliminate the deviation is calculated, a final duty ratio is calculated from the base duty ratio and the feedback correction amount, and the final duty ratio is applied to the supercharging pressure control valve 29, The feedback control of the supercharging pressure is performed such that the supercharging pressure PN follows the target supercharging pressure P0.

At step # 4, it is determined whether or not the engine CE is accelerating. In the present embodiment, after the throttle opening sharply increases, it is determined whether or not the vehicle is in an acceleration state based on whether or not the supercharging pressure PN approaches a predetermined range with respect to the target supercharging pressure P0. I have. Although it is possible to determine whether or not the vehicle is accelerating from the rate of change of the throttle opening, the period during which the vehicle is accelerating becomes extremely short. You will not be able to do it.

If it is determined in step # 4 that the vehicle is not in an acceleration state (NO), feedback control of the supercharging pressure is performed in steps # 5 to # 7. In this embodiment, only when the supercharging pressure PN is between the target supercharging pressure P0 and the boundary supercharging pressure PL set slightly lower than the target supercharging pressure P0, Feedback control is performed only when (P0−PN) is equal to or smaller than a predetermined width PK (= P0−PL), and when the supercharging pressure PN does not reach the boundary supercharging pressure PL, that is, when the deviation (P0−PN) is When the predetermined width PK is exceeded, the feedback control is not performed (the feedback correction amount is set to 0). Deviation (P0
−PN) is large and feedback control is performed.
This is because the integral value of the deviation increases, and hunting occurs due to the integral operation performed based on the integral value of the deviation.

Specifically, first, in step # 5, a feedback correction amount is calculated. This feedback correction amount is equal to the deviation (P0−
PN), a part proportional to the deviation (proportional operation part), a part proportional to the integral value of the deviation (integral operation part), and a part proportional to the rate of change of the deviation (differential operation part). A part of the three operations, for example, the differentiation operation may be omitted. Subsequently, in step # 6, a final duty ratio is calculated from the base duty ratio and the feedback correction amount. Next, in step # 7, the final duty ratio is output to the supercharging pressure control valve 29. Here, the pressure in the pressure chamber 26a of the actuator 26 changes according to the final duty ratio, and accordingly, the opening degree of the waste gate valve 25 changes, and a supercharging pressure corresponding to the final duty ratio is obtained. Thereafter, the process returns to step # 1.

When it is determined in step # 4 that the vehicle is accelerating (YES), step # 8 is executed.
~ In step # 12, the feedback control is stopped,
Acceleration correction, that is, supercharging pressure control for acceleration is performed.
Specifically, first, after the feedback correction is stopped in step # 8, the first acceleration correction is performed in step # 9. As described above, if the supercharging pressure is feedback-controlled during acceleration, a change in the supercharging pressure is delayed with respect to a change in the target supercharging pressure, and the acceleration performance is deteriorated. Therefore, after stopping the feedback control, the duty ratio is changed stepwise by a predetermined amount so that the supercharging pressure quickly approaches the target supercharging pressure. The correction amount of the duty ratio is the acceleration correction amount.

In step # 10, the deviation (P0-PN) of the supercharging pressure PN from the target supercharging pressure P0 is determined by a predetermined width PK.
(= P0−PL) is compared / determined.
Here, if it is determined that PK ≧ PO-PN, (N
O), since the supercharging pressure PN is already equal to or higher than the boundary supercharging pressure PL, a state has been reached in which feedback control can be performed. Therefore, the acceleration correction is stopped (reset) in step # 13, and thereafter, in steps # 5 to # 7
Then, after the same feedback control as described above is performed, the process returns to step # 1.

On the other hand, in step # 10, PK <P0-P
If it is determined to be N (YES), in step # 11,
It is determined whether the rate of change ΔP of the supercharging pressure PN with respect to time is smaller than a predetermined supercharging pressure stable state determination value DP. Here, if it is determined that DP> ΔP, (YE
S), the supercharging pressure PN hardly increases, and there is no possibility that the supercharging pressure PN will reach the boundary supercharging pressure PL. Therefore, the feedback control is not restarted as it is. Therefore, in this case, the second acceleration correction is performed in step # 12. That is, the duty ratio is further changed stepwise to increase the supercharging pressure PN. Thereafter, in step # 6, the final duty ratio is calculated based on the base duty ratio and the acceleration correction value (second time). Subsequently, in step # 7, the final duty ratio is output to the supercharging pressure control valve 29, and thereafter, the process returns to step # 1.

If it is determined in step # 11 that DP ≦ ΔP (NO), the supercharging pressure PN is increasing,
It is expected that the supercharging pressure PL will soon be reached (the deviation will be less than PK). Therefore, in this case, while maintaining the initial acceleration correction value, step # 6 to step # 7
Is executed, and the final duty ratio is output to the supercharging pressure control valve 29. Thereafter, the process returns to step # 1.

The supercharging characteristics during acceleration when such supercharging pressure control is performed will be described below with reference to FIG. As shown in FIG. 4, for example, when the throttle opening (G ₁₎ is changed in a substantially stepwise at time t _1, the target supercharging pressure P0 (G ₂₎ Along with this also changes substantially stepwise. When the acceleration state is detected at time t _2, the feedback control from the time t ₂ is stopped, therefore the feedback correction amount (G ₆₎ is zero. On the other hand, from the time t ₂ is performed first acceleration correction, acceleration correction amount (G ₅₎ is increased stepwise by a predetermined value h _1. Accordingly, the supercharging pressure PN increases. Here, the boost pressure if steadily rises as shown by curve G _3, eventually become supercharging pressure boundary supercharging pressure PL (G ₄₎ above, therefore feedback control is started,
Shortly supercharging pressure PN will correspond to the target boost pressure P0 (G _2).

On the other hand, when the discharge pressure of the supercharger 16 is low, the supercharging pressure PN stops rising before reaching the boundary supercharging pressure PL (G ₄ ) and becomes stable. However, thus supercharging pressure PN is if stable, the second acceleration correction is made at time t _4, the acceleration correction amount (G ₅₎ is increased to a predetermined value h ₂ by steps. Therefore, the boost pressure PN is started to increase again as indicated by the curve G ₃ ", eventually become time t ₅ at the border supercharging pressure PL (G ₄₎ above, the feedback control is started, shortly boost pressure PN (G ₃ ″) becomes equal to the target supercharging pressure P 0 (G ₂ ). Therefore, even when the discharge pressure of the supercharger 16 is low due to variations in the discharge performance of the supercharger, the supercharge pressure quickly and reliably follows the target supercharge pressure during acceleration.

When the first acceleration correction amount is set to a large value, as shown by the curve G ₃ ′, at the time t ₃ , the boundary supercharging pressure P
L (G ₄ ) is exceeded and feedback control is started immediately, but overshoot occurs. The acceleration correction amount, feedback correction amount, and deviation when such overshoot occurs are shown by curves G ₅ ′, G ₆ ′, and G ₇ ′, respectively. Therefore, according to the present embodiment, without causing overshoot during acceleration,
The supercharging pressure can quickly and surely follow the target supercharging pressure.

[0030]

According to the first aspect of the present invention, when the supercharging pressure is stabilized below the boundary supercharging pressure during acceleration, the supercharging pressure is further increased by the second supercharging pressure correcting means. Therefore, the supercharging pressure can reliably reach the boundary supercharging pressure. Therefore, the feedback control of the supercharging pressure is reliably started, and the supercharging pressure can quickly and surely follow the target supercharging pressure. Further, since the acceleration correction amount of the supercharging pressure correcting means can be set small, no overshoot of the supercharging pressure occurs during acceleration.

According to the second aspect, basically the same operation and effect as those of the first aspect can be obtained. Further, since the feedback control is forcibly prohibited during acceleration by the feedback inhibition means during acceleration, acceleration responsiveness is enhanced and control stability is enhanced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a system configuration diagram of an engine including a supercharging pressure control device according to the present invention.

FIG. 3 is a flowchart illustrating a control method of supercharging pressure control.

FIG. 4 shows throttle opening, boost pressure,
It is a figure which shows a temporal change of the acceleration correction amount, the feedback correction amount, the deviation, and the deviation change rate.

FIG. 5 shows a conventional supercharging pressure control device during acceleration.
It is a figure which shows the time-dependent change of a throttle opening degree, a supercharging pressure, a feedback correction amount, and an acceleration correction amount.

[Explanation of symbols]

 CE: Engine a: Supercharging pressure feedback control means b: Acceleration detecting means c: Supercharging pressure correcting means d: Feedback limiting means e: Second supercharging pressure correcting means f: Acceleration feedback inhibiting means 16: Supercharger 20 ... Control unit

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02B 37/12 302 F02B 37/18

Claims (2)

(57) [Claims] 1. A supercharging pressure feedback control means for feedback controlling a supercharging pressure so as to follow a target supercharging pressure set according to an operating state of an engine, and an acceleration detecting means for detecting an acceleration state of the engine. When the acceleration detecting means detects that the engine is in an accelerating state, a supercharging pressure correcting means for correcting the supercharging pressure to a high pressure side, and the supercharging pressure is set slightly lower than the target supercharging pressure. And a feedback limiting means for causing the boost pressure feedback control means to perform feedback control only when the boost pressure exceeds a predetermined boundary boost pressure. After the supercharging pressure is corrected to the high pressure side, when the supercharging pressure is stabilized at a pressure lower than the boundary supercharging pressure, the second supercharging pressure is corrected to the high pressure side again.
A supercharging pressure control device for an engine, comprising: 2. The engine boost pressure control device according to claim 1, further comprising an acceleration feedback prohibition unit that prohibits feedback control of the supercharge pressure during acceleration. Supercharging pressure control device.