JPS63129128A - Controlling method for supercharging pressure - Google Patents

Abstract

PURPOSE:To make accurate control over supercharging pressure performable as well as to improve a rate of fuel consumption, by adjusting a manipulated variable as a function of suction temperature and/or atmospheric pressure when the supercharging pressure of a supercharger is controlled, and controlling the supercharging pressure for feedback toward the specified desired value. CONSTITUTION:In a suction passage 8, there are provided with a compressor part 7 of a turbosupercharger 2, an intercooler 9 and a throttle valve 11 in order. At the upstream side of a turbine part 14 of the supercharger 2, there is provided with a variable nozzle 3 consisting of a lot of vanes, and each opening of the variable nozzle 3 is adjusted by an adjusting mechanism 4 whereby a flow velocity of exhaust gas is made controllable. This adjusting mechanism 4 is controlled by the supercharging pressure led into an actuator 20 via a control valve 18a. And, this control valve 18a is controlled by a control unit 17, and at this time, a manipulated variable as a function of suction temperature and/or atmospheric pressure is adjusted, whereby the control valve 18a is controlled for feedback so as to cause the supercharging pressure as a controlled variable to become the specified desired value.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for controlling the boost pressure of an internal combustion engine, and particularly to a method for controlling the boost pressure with excellent responsiveness and stability.

<Prior Art> Generally, since a supercharger is driven by engine exhaust gas or output shaft power, its driving force increases in accordance with the rotational speed of the engine, and the supercharging pressure increases accordingly. If the supercharging pressure is too high, there will be problems such as knocking, so it is desirable to appropriately control the supercharging pressure so that it is at the optimum value under all conditions. In the case of a so-called supercharger that is driven by the output shaft power of the engine, the supercharging pressure is controlled by intermittent driving force to the supercharger or by opening and closing a bypass passage. In this type of turbocharger, this is accomplished by using movable vanes to throttle the flow of exhaust gas supplied toward the exhaust vanes, or by opening and closing a wastegate valve.

In any type of supercharger, there is a time delay in the response of the boost pressure to the engine speed or throttle opening, so if feedback control is performed, the control characteristics are inappropriate. If this occurs, the control amount (boost pressure) may overshoot excessively or cause hunting, and if you try to stabilize feedback control by making it less susceptible to parameter fluctuations, the response of the system may change. Problems such as severe loss of sexuality may occur. In particular, it has been found that intake air temperature and atmospheric pressure are important control parameters.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main purpose of the present invention is to provide stable and highly responsive control of boost pressure regardless of the operating environment of the engine. The purpose is to provide a method.

According to the present invention, the object is to provide a method for controlling supercharging pressure in a supercharger driven by engine exhaust gas or output shaft power, comprising: To provide a supercharging pressure control method, which performs feedback control of supercharging pressure as a controlled variable toward a predetermined target value by adjusting a manipulated variable as a function of intake air temperature and/or atmospheric pressure. This is achieved by

<Effect> In this way, by performing control operations in consideration of the influence of important parameter values, it is possible to quickly and stably converge the boost pressure value toward the target value regardless of the engine operating environment. can.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a supercharging structure for an engine to which the present invention is applied. Intake air to be supplied to the engine 1 is sent from the air cleaner 5 through the intake passage 6 to the compressor section 7 of the supercharger 2 and is pressurized. It is supplied to the combustion chamber of the engine 1 via a passage 10.

A fuel injection valve 12 is provided in the intake passage 10 downstream of the throttle valve 11 . Exhaust gas from the engine 1 passes through the exhaust passage 13 to the turbine section 14 of the supercharging tff12.
After discharging the power for driving the compressor section 7, it is discharged to the atmosphere through the exhaust passage 15 and the muffler 16. A variable nozzle 3 consisting of a large number of annularly arranged vanes is provided on the upstream side of the turbine section 14. By adjusting the opening degree of the variable nozzle 3 with an adjustment mechanism 4, the turbine section The flow rate of exhaust gas flowing into 14 can be controlled.

The adjustment mechanism 4 is controlled by an actuator 20,
This actuator 20 has a positive pressure chamber 38 defined by a positive pressure diaphragm 25 that is always biased in one direction by a coil spring 33. Throttle valve 11 through
The intake passage 8 is connected to the upstream side of the intake passage 8. The control valve 18a is controlled to open and close by a control IT device 17 that uses the engine rotational speed Ne and the throttle opening θth as parameters.

A rod 28 is fixed to the center of the diaphragm 25 of the actuator 20, and the shaft end of the rod 28 is connected to the adjustment mechanism 4 described above.

The control valve 18a is subjected to duty ratio control by the control device 17, and FIG. 2 shows a simplified control program executed by the control device 17 to generate the control amount @D.

First, when the power is turned on, variables are cleared in ST1, self-diagnosis, etc. are performed, and in ST2, a temporary control target is set from a map built into the control device based on the throttle opening θ and engine speed Ne. value P and temporary control signal D
Read O. In ST3, the current boost pressure value P2. n
and the previous boost pressure value p2. Find the difference ΔPO from n-1.

Next, in ST4, the increment ΔPT of the target boost pressure value PT is read out from the table as a function of ΔPD, that is, the rate of change of the boost pressure value, and in ST5, the boost pressure target value PT is changed to this increment.
Correct by an amount corresponding to T. In ST6, find the difference ΔP2 between the target boost pressure value PT and the actual boost pressure value P2,
In addition, in ST7, constants KT and ^ are obtained from tables, respectively, in order to take into account the influence of intake air temperature TA and atmospheric pressure P^. In ST8, it is determined whether ΔP2 is greater than or equal to 0 or less than 0, and if ΔP2 is greater than or equal to 0, that is, the actual boost pressure value P2 is equal to the target boost pressure 11! P T
If it is less than 5T, substitute +1 for index I.
9), when ΔP2 is less than 0, that is, when the boost pressure value P2 exceeds the target boost pressure value PT, the index I is -1.
(ST10).

At 5T11, it is determined whether the index I has changed from the previous value. If the index I has not changed, that is, if the actual supercharging pressure value P2 does not cross the target supercharging pressure value 2, it is determined whether the absolute 110 of ΔP2 is greater than the constant G at 5T12. It will be judged. When the absolute value of ΔP2 is larger than G, that is, when the actual supercharging pressure value P2 must be brought closer to the target supercharging pressure value 2, 5T13 to 5T1
In step 5, the constants KP and KI for proportional control and integral control are obtained from the table for each engine rotational speed of 1 ute, and the modified ff1DP is calculated using these constants.
, find DI. Next, at 5T16, a DI limit check is performed, and at 5T17, the control signal is calculated. At this time, {circle around (2)} and KA are taken into consideration in the constants for compensating the intake air temperature and atmospheric pressure calculated in ST7.

Next, 5T18 performs a limit check on the control signal, which takes into account the non-linearity of the diaphragm actuator and forcibly maintains the value of the control signal within a range where the actuator characteristics are approximately linear. It is something to do. Furthermore, at 5T19, a control signal is output, and the process returns to ST2.

As described above, the actual boost pressure value P2 is set to the target boost pressure *
Control is performed to bring it closer to PT, but if it is determined at 5T11 that the value of ■ has changed compared to the previous value, then at 5T21 D^ is
is read out from the table and the value of the integral control correction term DI is corrected using this DA (5T22>). At the same time, the proportional control correction term DP to is set (5T23), and the process proceeds to 5TI6.

5TI2, if it is determined that the absolute value of ΔP2 is smaller than G, that is, the actual boost pressure value P2 is the target boost pressure value P.
If it is determined that it is approximately equal to T, the value of DI is saved as is, DP is set to O, and the process proceeds to 5T17.

As explained above, the control method of this embodiment is based on proportional-integral control using a digital CPU;
As represented by T3 to ST6, the actual boost pressure value P
If the rate of change ΔP2 of 2 is large, the target supercharging pressure value 2 is set to be separated from the actual supercharging pressure value P2, so the actual supercharging pressure value P2 should be brought closer to the target supercharging pressure value PT. The effect of -m becomes stronger, and the actual boost pressure value converges to the target boost pressure value more quickly. Also, ST8～
As expressed by 5T23, since the magnitude of the integral term DI is reduced when the actual boost pressure value P2 crosses the target boost pressure value PT, the boost pressure value can be converged even more quickly. I can do it.

In particular, the constants KT and KA for compensating the intake air temperature and atmospheric pressure obtained in ST7 are taken into account in the process of calculating operation m in ST17, so they are always stable regardless of the engine operating environment. Moreover, it becomes possible to control the supercharging pressure with good responsiveness.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above, but the present invention is applicable to on/off control of the input shaft in a supercharger, opening/closing control of a bypass valve, or waste l-gate valve in a turbo charger. Furthermore, the present invention is equally applicable to two-stage turbo or hybrid supercharging structures that use multiple superchargers of the same or different types.

<Effects of the Invention> As described above, according to the present invention, it is possible to always control the boost pressure with high accuracy and stability regardless of the engine operating environment, which has a great effect on improving engine performance and fuel efficiency. can play.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the boost pressure structure of an engine to which the present invention is applied. FIG. 2 is a flow diagram showing an embodiment of the boost pressure control method according to the present invention. 1... Engine 2... Supercharger 3... Variable nozzle 4... Adjustment mechanism 5... Air cleaner
6...Intake passage 7...Compressor 8...
Intake passage 9...Intercooler 10...Intake passage 11...Throttle valve 12...Injection valve 13...
Exhaust passage 14...Turbine section 15...Exhaust passage 16...Muffler 17...Control device 1
8... Pipe line 18a... Control valve 20... Actuator 25... Positive pressure diaphragm 28... Rod 33... Coil spring 38...
... Positive pressure chamber patent applicant Honda Motor Co., Ltd.
Attorney Patent Attorney Yo Oshima - Figure 1

Claims (1)

[Claims] (1) A method of controlling boost pressure in a supercharger driven by engine exhaust gas or output shaft power, in which the control amount is controlled by adjusting the manipulated variable as a function of intake air temperature and/or atmospheric pressure. 1. A method for controlling boost pressure, comprising performing feedback control of boost pressure toward a predetermined target value.