JPH02227522A - Supercharging pressure control device - Google Patents

Abstract

PURPOSE:To solve lack of supercharging pressure caused by revolution response delay and so on of a turbine by controlling a solenoid valve constituting an actuator of a waste gate valve of a supercharger by a duty signal acquired by adding an acceleration correction duty ratio to a basic duty ratio at the time of acceleration. CONSTITUTION:In an engine with turbo charger, a waste gate valve 11 is installed in a bypass passage 12 provided bypassing a turbine 4b, and a vane 4c at the inlet of the turbine 4b as a supercharging pressure control device 10. And the waste gate valve 11 and the vane 4c are driven by diaphragm type actuators 13 and 14, and each of the actuators 13 and 14 are driven by supercharging pressure or intake negative pressure which has passed a three way solenoid valve 16. In this case, a basic duty ratio map in which a target supercharging pressure can be obtained in each driving condition and an acceleration correction duty ratio map are set, and output is acquired by adding the acceleration correction duty ratio to the basic duty ratio at the time of acceleration.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a supercharging pressure control device for a vehicle turbocharged engine, and more particularly, to an acceleration correction system that performs feedforward control of the opening degree of a wastegate valve. Regarding countermeasures.

[Conventional technology]

Generally, in a turbocharged engine, a bypass passage with a wastegate valve is provided for the turbocharger turbine, and in the turbo region, the wastegate valve is opened to release a portion of the exhaust gas, thereby controlling the boost pressure to be approximately constant. This is done to suppress the occurrence of knocking. In this case, if the opening and closing of the wastegate valve is controlled using the supercharging pressure at the outlet of the compressor, the supercharging pressure will greatly overshoot during transients such as acceleration, resulting in hunting, which is undesirable. For this reason, it has been proposed to control the boost pressure by electronically controlling the opening degree of the wastegate valve according to each operating condition.

Conventionally, there is a prior art technique for electronic control of the supercharging pressure, as disclosed in, for example, Japanese Patent Application Laid-Open No. 61-55316. Here, the deviation between the boost pressure detected by the boost pressure sensor and the target boost pressure is calculated, and the boost pressure is feedback-controlled by adding the proportional part CP) and the integral part (rito) based on this deviation. It has been shown that

[Problem to be solved by the invention]

By the way, according to the feedback control of the above-mentioned prior art, follow-up control is performed by determining the limit 8ffi based on the deviation of the boost pressure, so follow-up control is not performed for characteristics where the boost pressure is delayed and then suddenly increases during a transient period. As a result, the supercharging pressure peak cannot be sufficiently suppressed. For this reason, the supercharging pressure overshoots to a relatively large extent, which tends to cause knocking.

Here, in order to reduce the overshoot of the boost pressure, it is suitable to preset a map of the basic duty ratio so that the target boost pressure is achieved under each operating condition, and perform feedforward control using this map. However, according to this feedforward control, if mechanical inconveniences occur during acceleration, such as a delay in the response of the rotational speed of the turbine wheel, it cannot be corrected. For this reason, a lack of supercharging pressure occurs while the rotation of the turbine is delayed immediately after acceleration, and it is desirable to take measures to correct this.

The present invention has been made in view of the above points, and an object of the present invention is to provide a supercharging pressure that can appropriately correct a lack of supercharging pressure during acceleration in feedforward control of supercharging pressure. The purpose is to provide a control device.

[Means to solve the problem]

In order to achieve the above object, the supercharging control device of the present invention includes:
In a control system in which a solenoid valve is installed in the wastegate valve actuator of a turbocharged engine and the boost pressure is controlled by a duty signal, a basic duty ratio map is defined so that the target boost pressure is achieved under each operating condition,
Set the acceleration correction duty ratio map, and when accelerating,
The acceleration correction duty ratio is added to the basic duty ratio and the result is output.

[For production]

Based on the above configuration, during steady operation, the opening degree of the wastegate valve of the turbocharger is feedforward controlled by the basic duty ratio map, and the boost pressure is controlled so as to always match the target boost pressure. During acceleration, the rotation delay of the turbine is corrected by the acceleration correction duty ratio, so that insufficient boost pressure does not occur. .

[Example] Embodiments of the present invention will be described below based on the drawings.

In Fig. 1, the outline of a turbocharged engine to which the present invention is applied will be described. Reference numeral ``l'' is the engine body, and in the intake system, the air cleaner 2 is connected to the compressor 4a side of the turbocharger 4 through the intake pipe 3. 1. Downstream of this compressor 4a is a throttle valve 5. It communicates with the engine body 1 via a chamber 6 and an intake manifold 7. Further, an exhaust manifold 8 from the engine body is unified and communicates with the turbine 4b side of the turbocharger 4, and this turbine 4b communicates with the trachea 9.

Therefore, as the boost pressure control device IO, the turbine 4bl::
Bypass passage 1 with wastegate valve 11 against
2 communicate with each other, and diaphragm actuators 13 and 14 are attached to this wastegate valve 11 and a vane 4C installed at the inlet of the turbine 4b.

On the other hand, a boost pressure passage 15 downstream of the compressor 4a communicates with a solenoid valve 16 in three ways, and this solenoid valve 16
from the control passage 17 to the actuator 13.14;
A leak passage 18 having an orifice 19 communicates with the upstream side of the compressor 4a. In the solenoid valve 1B, the valve body teb having the solenoid 1fla is connected to the boost pressure port 1.
6e is configured to open and close the leak port 16d, and adjusts the opening and closing times of the supercharging pressure boat 16c and the leak boat 16d according to the duty signal of the control unit 30, and controls the wastegate valve 11.6e together with the pressure of the actuator 13.14. The opening degree of the vane 4C is controlled.

In FIG. 2, the control system of the control unit 30 will be described.

First, the air flow meter 2 that measures the air flow rate Q
1. Engine rotation speed sensor 22 that detects engine rotation speed Ne. It has a throttle opening sensor 23 that detects the throttle opening θ and a pressure sensor 24 that detects the supercharging pressure P, and these signals are manually input to the control unit 30.

The control unit 30 is configured as a feedforward control system, and has a basic duty search section 31 into which the air flow rate Q and engine rotational speed Ne are input, and the basic duty search section 31 includes a basic duty ratio map setting section. 32 are provided. The map of basic duty ratio D[3 is
As shown in figure (a), airflow ff1Q and engine speed Ne
The target supercharging pressure p is always maintained under each steady-state operating condition
It is set to obtain t. That is, the engine speed Ne
In a low load range where the air flow rate Q is small, the value of the basic duty ratio D[3 is large, and the leak time by the solenoid valve 1B is increased to reduce the actuator pressure. Further, as the engine speed Ne and the air flow rate Q increase, the value of the basic duty ratio DB decreases, and the actuator pressure increases. Therefore, the basic duty search section 31 searches for the basic duty ratio Dll using the above map and outputs it to the duty ratio determination section 33.

In addition, the throttle opening change calculation unit 34 manually calculates the throttle opening change dθ/dt, and calculates the acceleration of the engine rotation speed Ne, the throttle opening θ, and the throttle opening change dθ/di. The detection unit 35 is manually operated. Then, the set value Nl of the engine speed Ne (for example, 4
000rpa+), the set value θ of the throttle opening θ] (for example, 80 degrees), and the set value a of the throttle opening change dθ/di, Ne <Nl, θ less θI.

Acceleration is determined when the change in throttle opening θ is large in the partial region where dθ/dt>a.

On the other hand, the supercharging pressure P is input to the supercharging state determination section 36, and the supercharging state is determined based on the supercharging pressure change dP/dt.
A correction signal is output after a certain period of time T has elapsed since the boost pressure decreased to ≦0. These acceleration and correction signals and engine speed Ne are input to an acceleration duty search section 37, which searches for and outputs an acceleration correction duty ratio Da from a map setting section 38. The acceleration correction duty ratio Da is set as a decreasing function with respect to the engine rotation speed Ne, as shown in FIG. 3(b).

The duty ratio determination unit 33 uses the above-mentioned basic duty ratio D.
The output duty ratio is calculated and determined by D=DB +Da using B and the acceleration correction duty ratio Da. A signal corresponding to this output duty ratio is outputted to the solenoid valve ta via the drive section 39.

Next, the operation of the supercharging pressure control device having such a configuration will be described using the flowchart of FIG. 4 and the time chart of FIG. 5.

First, when the engine is operating, exhaust energy drives the turbine 4b of the turbocharger 4 and rotates the compressor 4a, so that air in the intake system is pressurized and supplied to the engine body 1 to perform supercharging.

At this time, the air flow ff1Q and the engine speed No are input to the basic duty search section 31 of the control unit 30, and the basic duty ratio DB corresponding to the air flow rate Q and the engine speed Ne is searched by the map. During steady operation, a duty signal of the basic duty ratio DB is output to the solenoid valve 16 to control the pressure of the actuator 13, 14. Therefore, air flow jlQ, engine speed N
When θ is small, the actuator pressure becomes low and the wastegate valve 11 is closed, and the turbine vane 4c is closed.
opens to encourage supercharging. Furthermore, when the air flow rate Q and the engine speed Ne increase, the value of the basic duty ratio DB decreases, the actuator pressure increases, the waste gate valve 11 is opened by a predetermined amount, a part of the exhaust energy is released, and the vane 4c is used to exhaust the exhaust energy. The driving force of the turbocharger 4 is limited by reducing the gas flow rate. In this way, by feedforward control using the basic duty ratio DB of the map, the supercharging pressure is controlled to match the target supercharging pressure Pt.

Next, during acceleration when the throttle opening θ suddenly opens, the engine speed Ne increases and the boost pressure P rises as shown in Fig. 5, but in this case, the value of the basic duty ratio DB is set small according to the map. By performing feedforward control as described above, the supercharging pressure P increases without overshooting. In this case, under conditions where there is a sudden acceleration with a large change in the throttle opening θ and which causes a delay in the response of the turbine, the acceleration detection unit 35 determines that the acceleration is an acceleration, and the acceleration correction duty ratio D is determined according to the engine speed No.
A is searched on the map. On the other hand, the supercharging state in this case is determined by the supercharging state determination unit 3B, and after a certain period of time T from the supercharging pressure drop of dP/dt≦0, the acceleration correction duty is The ratio Da is output.

The duty ratio is then increased and corrected by adding the acceleration correction duty ratio Da to the basic duty ratio DI3. Therefore, the turbocharger 4 closes the wastegate valve 11 slightly from the open state to promote supercharging. become. As a result, the boost pressure P recovers from the lack of boost pressure due to the turbine response delay shown by the - dotted chain line and matches the target boost pressure pt, as shown by the solid line.

On the other hand, the acceleration correction duty ratio Da is the engine rotation speed Ne
It decreases as the value increases, and after a predetermined time, it becomes zero and the acceleration correction ends. However, during this time, the rotation delay of the turbine is resolved, so that control of steady operation using only the basic duty ratio DI3 is returned to, and supercharging pressure control that matches the target supercharging pressure PL is performed.

Although one embodiment of the present invention has been described above, it is not limited thereto.

〔Effect of the invention〕

As described above, according to the present invention, since the boost pressure control of a turbocharged engine is based on feedforward control using a basic duty ratio map, stable boost pressure control with little overshoot can be achieved. It can be done.

Furthermore, since the basic duty ratio is corrected by the acceleration correction duty ratio during acceleration, it is possible to appropriately eliminate the lack of boost pressure caused by mechanical factors such as a delay in the rotational response of the turbine.

Furthermore, since the correction during acceleration is performed after the supercharging pressure has decreased, no overshoot occurs due to the correction.

Furthermore, since the acceleration correction duty ratio is set according to the engine speed, there is no need to correct it more than necessary when the engine speed increases during acceleration.

[Brief explanation of the drawing]

Figure 1 is an overall configuration diagram showing an embodiment of the boost pressure control device of the present invention, Figure 2 is a block diagram of the control system, and Figures 3 (a) and (b) are basic and acceleration correction duty ratios. FIG. 4 is a flowchart showing the effect of supercharging pressure control, and FIG. 5 is a time chart of the same. 4...turbocharger, ll...wastegate valve, 13. 14...actuator, 1B...
Solenoid valve, 30... Control unit, 31... Basic duty search section, 33... Duty ratio determination section,
35... Acceleration detection unit, 37... Acceleration duty search unit lE5 Figure $4

Claims (3)

[Claims] (1) In a control system in which a solenoid valve is installed in the actuator of the wastegate valve of a turbocharged engine and the boost pressure is controlled by a duty signal, a basic duty ratio map is established to achieve the target boost pressure under each operating condition. , an acceleration correction duty ratio map, and during acceleration, the acceleration correction duty ratio is added to the basic duty ratio and outputted. (2) The boost pressure control device according to claim 1, wherein the correction based on the acceleration correction duty ratio is performed after a certain period of time after the rate of increase in boost pressure decreases during acceleration. (3) The boost pressure control device according to claim (1), wherein the acceleration correction duty ratio is determined according to the engine rotation speed.