JPH02115526A - Supercharging pressure controlling device of engine - Google Patents

Abstract

PURPOSE:To change supercharging pressure with good response and stabilize driving performance by installing a feedback control means to correct the amount of control of a supercharging pressure control valve, and an open control means to start feedback control at a specific time. CONSTITUTION:An engine E is equipped with a turbocharger 1. Pressure is introduced into a diaphragm device 9 through a supercharging pressure introducing passage 10, and part of the pressure is attenuated by a solenoid valve (supercharging pressure control valve) 11. On the other hand, when the supercharging pressure is still high after the attenuation, a waist gate valve 8 is opened. When a goal supercharging pressure is to be changed upward, the supercharging pressure can be quickly raised. The supercharging pressure can be changed with good response this way to obtain stabilized driving performance.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a boost pressure control device for an engine equipped with a supercharger.

(Prior Art) In a supercharged engine, the idea of maintaining reliability and improving engine output by controlling supercharging pressure according to engine speed has been known for a long time. For example, in a turbocharged engine described in Japanese Patent Application Laid-Open No. 59-49408, a wastegate valve is provided in a branch passage that bypasses the turbine.
The operating pressure of the actuator that drives this waste gate valve is controlled by a DETI solenoid valve. In this type of boost pressure control device, a target boost pressure is set in advance according to the engine speed, and a duty value for obtaining the target boost pressure is set. Also, with the above duty value as the basic duty,
Furthermore, feedback correction is performed based on the difference between the actual boost pressure and the target boost pressure.

It is also being considered to fully close the wastegate valve of the turbocharger for a predetermined period of time when the required boost pressure is changed to increase, such as during acceleration, to increase the boost pressure and improve acceleration performance ( For example, JP-A-58-1878
(See Publication No. 14).

(Problems to be Solved by the Invention) However, if such acceleration correction of the boost pressure is performed, the boost pressure may rise too much during small accelerations, and if the acceleration correction is prohibited to prevent this, A problem arises in that the responsiveness of boost pressure changes deteriorates during small accelerations.

The present invention has been made to solve the above problems, and is an overcharging engine that can change the boost pressure with good response even during small accelerations and can stably control the boost pressure. The purpose is to provide a supply pressure control device.

(Structure of the Invention) In order to achieve the above object, the present invention includes a supercharger, a supercharging pressure control valve that controls the supercharging pressure of the supercharger, as shown in FIG.
An engine operating state detection means, and a control variable that receives the output of the operating state detection means and sets a basic control amount of the boost pressure control valve for obtaining a target boost pressure set in advance according to the operating state. a setting means, a supercharging pressure detecting means, and a feedback control means for receiving an output of the supercharging pressure detecting means and correcting a control amount of the supercharging pressure control valve so that the supercharging pressure matches the target supercharging pressure. , when the target boost pressure is changed to increase, the feedback control of the boost pressure is stopped for a predetermined period, the control amount is changed in the direction of increasing the boost pressure, and the boost pressure reaches a value lower than the target boost pressure by a predetermined value. and an open control means for changing the control amount in a direction of decreasing the supercharging pressure at a speed proportional to the magnitude of the supercharging pressure increasing speed at that time, and starting the feedback control when the basic control amount is reached. It is characterized by

As a result, when changing the target boost pressure, the boost pressure can be quickly increased to near the target boost pressure, and the boost pressure corresponding to the target boost pressure can be increased at a rate that matches the boost pressure increase speed. By reducing the control amount to the control amount of the control valve and starting the feedback control of the boost pressure from that point, the control amount after the start of the feedback control can be stabilized.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, engine E has turbocharger 1
A throttle valve 3 is provided in the intake passage 2 of the engine E downstream of the compressor 1a of the turbocharger 1, and a boost pressure sensor 5 is provided in the surge tank 4 downstream of the throttle valve 3. .

On the other hand, the exhaust passage 6 has a turbine 1 of the turbocharger 1.
b, and a wastegate passage 7 that bypasses the turbine 1b.
and a wastegate valve 8 are provided, and the wastegate valve is driven to open and close by a diaphragm device 9.

Pressure is introduced into the diaphragm device 9 via a boost pressure introduction passage 10, and a part of the pressure is diluted by a solenoid valve (supercharge pressure control valve) 11, while when the boost pressure after dilution is high. The wastegate valve 8 is opened.

The solenoid valve 11 is connected to the boost pressure sensor 5. Engine speed sensor 12. Duty control is performed by a control unit 14 in response to the output of a throttle opening sensor 13 that detects the opening of the throttle valve 3.

Next, the procedure for setting the duty ratio D (%) of the solenoid valve 11 will be explained using FIG.

This flow is started at regular intervals, and S indicates a step.

First, SL is the engine operating state parameters such as throttle opening θ, engine speed N, and current boost pressure P.
(i) is read from each sensor 5, 12.13, and the target supercharging pressure P is determined according to the output value.

is read from the map shown in FIG. 4, and the map shown in FIG.

Read the normal (when the target boost pressure is not changed) basic duty ratio Db from the

When it is determined in S2 that the duty ratio correction value Dc for changing the target boost pressure increase is O, the target boost pressure P is changed in S3.
. is significantly higher than the boost pressure P(i) (d
o is a fixed value) to determine whether to increase the target boost pressure. If it is determined No here, in S5, △Dfb is read from the map shown in FIG. 6, the feedback correction amount Dfb is calculated, and S
In step 5, the final duty ratio is set as the sum of Db, Dc, and Dfb.

If YES is determined in S3, the DC value is determined in S6, and the DC value is determined in S5.
The duty ratio set in is calculated backwards and set to be 95%, and the process proceeds to S5.

When it is determined in S2 that the DC value is not 0, the boost pressure P(i) becomes the target boost pressure P in S7. More constant 11d+(do
It is determined whether or not the value has exceeded the lower value (less than Dc), and if the value has not been exceeded, the process proceeds to 85 without changing the value of Dc. If it exceeds, it is determined in S8 whether a reduction amount Dd for reducing Dc per time has been set. If it is not set, Dd=0, so Dd is determined from the map in Figure 7 in S9.
d is set and the value of Dc is decreased by the set value in SIO.

That is, in S10, P is a value proportional to the rate of change in supercharging pressure at the time when P(i)>Po dt for the first time in S7.
(i) The larger the value of -P (i-1), the larger the value of Dd is set, and therefore the faster the duty ratio decreases.

In S11, as a result of subtraction of 510, when the DC value is less than O, the next control is a feedback control step 83. S
In order to perform step 4, set the values of DC and Dd to 0 in Si2 and perform S5.
If not, proceed directly to S5.

When the above control is performed, the supercharging pressure P increases as shown in FIG.

When the duty ratio changes and the rate of increase in boost pressure is high, as shown by the solid line in Figure 8, and when the rate of increase in boost pressure is relatively small, as shown in the dashed-dotted line, the target boost pressure is not reached. Migration can be done quickly.

Additionally, the overshoot of the boost pressure can be reduced, and feedback control of the boost pressure can be performed from the point when the boost pressure is close to the target boost pressure and the control amount of the boost pressure control valve becomes the normal basic control amount. Since this is started, the control amount during feedback control is stabilized, and a stable operating state can be obtained.

In the above embodiment, control was performed by detecting the boost pressure downstream of the throttle valve, but the present invention may also be controlled using the boost pressure upstream of the throttle valve. May be applied.

(Effects of the Invention) As explained above, in the present invention, when changing the increase in the target boost pressure, the boost pressure can be increased quickly, and the rate of increase in the boost pressure can be absorbed to quickly reach the target boost pressure. It can be converged and stable operating performance can be obtained at the start of feedback control.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of the present invention, Fig. 2 is an overall system diagram of an embodiment of the present invention, Fig. 3 is a flowchart for executing control of the embodiment, and Figs. 4 to 7 are the same implementation. The map referred to in the example flowchart, FIG. 8, is a graph showing changes over time in the boost pressure and the control amount of the boost pressure control valve. 1...Supercharger (turbocharger), 5...
...Supercharging pressure sensor, 7...Wastegate passage, 8...Wastegate valve, 9...
Diaphragm device, 11... Solenoid valve (supercharging pressure control valve), 12... Engine rotation speed sensor, 13... Throttle opening sensor, 14...
···control unit.

Claims (1)

[Claims] A supercharger, a supercharging pressure control valve that adjusts the supercharging pressure of the supercharger, an engine operating state detecting means, and a supercharging pressure control valve that receives the output of the operating state detecting means and is set in advance according to the operating state. a control amount setting means for setting a basic control amount of the boost pressure control valve to obtain a target boost pressure; a boost pressure detecting means; Feedback control means corrects the control amount of the boost pressure control valve to match the boost pressure, and when the target boost pressure is changed, the feedback control of the boost pressure is stopped for a predetermined period and the control amount increases the boost pressure. When the boost pressure reaches a predetermined value lower than the target boost pressure, the control amount is changed in the direction of decreasing the boost pressure at a speed proportional to the boost pressure increase rate at that time. and open control means for starting the feedback control when the basic control amount is reached.