JPH0381528A - Supercharge pressure controller of engine with supercharger - Google Patents

Abstract

PURPOSE:To prevent damage of an engine or an exhaust system by providing a means which decreases supercharge pressure control in the vicinity of an operation condition at he time of an over supercharging condition. CONSTITUTION:A control unit 15 receives output signals on the engine operation of an engine from a throttle opening sensor 25, an atmospheric pressure sensor 26, an engine speed sensor 27, a travel distance sensor 28, a supercharge pressure sensor 29 and the like to calculate target supercharge pressure and detect real supercharge pressure through the the sensor 29 so as to feed back the real supercharge pressure such that it may become the target supercharge pressure. Under fuel injection control by the unit 15, when the real supercharge pressure is more than a limited supercharge pressure, primary and secondary fuel injection valves 10, 11 are closed so as to cut the fuel injection. It is judged whether the cutting is performed or not. In the case that fuel cut is performed, base duty is lowered only by a specified value based thereon so as to decrease supercharge pressure control. Consequently, the fuel cut is prevented from being repeated intermittently.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boost pressure control device for a supercharged engine.

[Conventional technology]

As a supercharging pressure 5till'+TN device for a supercharged engine, for example, as disclosed in Japanese Patent Application Laid-Open No. 16240/1980, the actual supercharging pressure set according to the operating state of the engine is It is known that a feedback control section is used so that the supercharging pressures of

Furthermore, as disclosed in Japanese Utility Model Application Publication No. 59-127847, etc., when the supercharging pressure exceeds the limit supercharging pressure, it is possible to There are already known configurations in which the engine output is reduced to protect the engine and the like, and in which a means for cutting fuel supply is provided as a means for further reducing the engine output.

[Problem to be solved by the invention]

However, since both the target boost pressure and the fuel cant line in the over-supercharged state are fixed values for each engine speed, they may vary during continuous acceleration, etc. depending on variations in the supercharger, plowing pressure, etc. As shown in FIG. 6, the overcharging pressure state and the fuel cant state are intermittently repeated. Therefore, there have been problems such as damage to the engine and damage to the catalyst in the exhaust system due to repeated rapid changes in exhaust temperature.

[Means for solving the problem] A supercharging pressure control device for a supercharged engine according to the present invention includes:
In order to solve the above problems, the system is equipped with a supercharging pressure control means that controls the supercharging pressure according to the operating state of the engine, and a fuel control means that performs fuel cant when overcharging exceeds the limit supercharging pressure. The supercharging pressure control device for a supercharged engine is characterized by providing means for reducing the supercharging pressure control amount in the vicinity of the operating state when an over-supercharging state occurs.

[Function] According to the above configuration, even in the method of performing fuel cut-off at the time of over-supercharging, when the over-supercharging state occurs, the supercharging pressure control amount in the vicinity of the operating state is reduced. This eliminates repeated occurrences of overcharging, prevents repeated intermittent fuel cant, and provides greater protection for the engine and exhaust system.

(Example) An example of the present invention will be described below based on FIGS. 1 to 5.

FIG. 1 is an overall configuration diagram of a supercharging pressure control device for a supercharged engine in this embodiment. In FIG. 1, a boo core 3 is installed in an intake passage 2 of a rotary piston engine 1, which is an example of a supercharged engine, and a blower 3 is driven by a turbine 5 installed in an exhaust passage 4 to intake air. It is designed to apply a force of 11 pressures and release it. Above intake passage 2
An air cleaner 6 and an air flow meter 7 are provided upstream of the blower 3, and an intercooler 8, a throttle valve 9, and a next fuel injection valve 10 and a secondary fuel injection valve 11 are provided downstream. It is provided. These fuel injection valves 1o and 11 are provided with a hand 76 so that fuel in a fuel tank 12 is supplied by a fuel pump 14 via a fuel passage 13.

Further, the fuel injection valves 10 and 11 are controlled by a control unit 15 controlled by a microcomputer. That is, the control unit 15 is configured to calculate the fuel supply amount according to the intake air amount based on the output signal from the air flow make 7, and control the opening time of the fuel injection valves 10 and 11. Moreover, the fuel passage 1
3 is provided with an anti-pulsation damper 16 for preventing pulsation in the fuel supply, and a pressure regulator 17 for adjusting the fuel supply pressure to a predetermined pressure.

The exhaust passage 4 is provided with a bypass passage 2o that bypasses the turbine 5 and relieves the exhaust pressure upstream of the turbine 5 downstream of the turbine.

The bypass passage 20 is provided with waste gates 1 to 21 that adjust the flow area of the bypass m passage 20, control the amount of exhaust gas flowing through the bypass passage 2o, and control the supercharging pressure. There is. The waste 1 to gauge I valve 21 has a normal diaphragm structure, and although not shown, its pressure chamber is communicated with the downstream side of the turbine 5 in the intake passage 2 via a pressure passage 22. Supply pressure is introduced.

Further, the pressure passage 22 is communicated with a portion of the intake passage 2 between the air flow meter 7 and the blower 3 via a relief passage 23, and is provided with a duty solenoid valve 24 for opening and closing the relief passage 23 of the bracket. It is being The duty ratio of the operation of the duty solenoid valve 24 is controlled by the control unit 15, and the boost pressure from the pressure passage 22 is relieved according to the duty ratio. The pressure acting on the waste gate valve 21 is controlled to adjust the opening degree of the waste gate valve 21, thereby adjusting the supercharging pressure.

The control I/roll unit 15 includes a throttle opening sensor 25, an atmospheric pressure sensor 26, an engine rotation speed sensor 27, a vehicle mileage sensor 28, a supercharging pressure sensor 29, etc. for detecting the operating state of the engine. The output signal from the sensor is input manually. control unit 15
calculates the target boost pressure in accordance with the output signals from the various sensors regarding the engine operating state, detects the actual boost pressure by the boost pressure sensor 29, and determines whether the actual boost pressure is Feedback control is performed so that the target boost pressure is achieved.

Next, based on FIG. 2, the supercharging pressure control operation by the control unit 15 will be described.

First, signals from various sensors for detecting engine operating conditions etc. are measured (Sl), and then based on the measurement results regarding engine speed and throttle opening, the pace is determined according to the operating condition based on a predetermined map. Duty is calculated (S2).

At that time, corrections are made based on travel distance, atmospheric pressure, etc., as necessary.

Next, in the same way, based on the measurement results regarding the engine speed and throttle opening, the target boost pressure for that operating state is calculated based on a predetermined map, and similar corrections are made based on the mileage and atmospheric pressure (S3 ). The map of the target boost pressure (POB) set corresponding to the engine speed (NE) and the throttle opening (TVO) is as shown in FIG.

Next, calculate the actual boost pressure by averaging the output j signals from the boost pressure sensor 29, calculate the difference between it and the target boost pressure obtained as described above (S4), and further calculate this difference. Based on a predetermined map, a correction amount of the duty to be fed back is calculated based on the pressure (S5). At that time, it is determined whether or not the vehicle is being accelerated, and if the force is U, a corresponding correction is made. Thereafter, the duty to be output is calculated by adding the duty correction amount obtained in step S5 to the pace duty calculated in step S2 (S6), and the duty solenoid valve 24 is adjusted based on the last output duty. It is driven (S7).

The feedback control of the boost pressure described above is performed, for example, at a 90° rotation period of the engine crank.

On the other hand, in parallel with the supercharging pressure control as the main flow, as shown in FIG. 3, over-supercharging pressure state detection and correction control are performed at a high speed cycle of, for example, 10 m5ec.

In Figure 3, data such as engine speed and pace duty are first read (Sll), and then fuel cut is achieved when the actual boost pressure exceeds the limit boost pressure set in advance as the limit boost pressure. It is determined whether or not (S12
).

That is, in the fuel injection control by the control unit 15, when the actual boost pressure exceeds the limit boost pressure, the secondary and secondary fuel injection valves 10 and 11 are closed to cut fuel injection. Then, it is determined whether or not this fuel cut has been performed. If fuel cuts are being threatened,
A correction amount that lowers the pace duty by a predetermined value at the engine speed before and after the fuel cut and the throttle opening if necessary is determined (S13), and based on this, the pace duty calculation in step S2 of FIG. 2 is performed. Correct the pace duty of the pace map (S14)
. Note that if the fuel cut is not threatened, normal control is continued (S15).

As a result, as shown in Fig. 4, when the boost pressure exceeds the limit boost pressure and the fuel supply is cut, the pace duty is reduced by a predetermined value based on this. Since the supply pressure control amount is reduced, an over-supercharging state will not occur even if the same operating state continues thereafter. Therefore, it is possible to reliably prevent damage to the engine due to intermittent repetition of fuel leakage, and damage to the catalyst, etc. of the exhaust system due to repeated rapid temperature changes of the exhaust gas.

〔Effect of the invention〕

The boost pressure control device for a supercharged engine according to the present invention includes:
As described above, the supercharger is equipped with a supercharging pressure control means that controls the supercharging pressure according to the operating state of the engine, and a fuel control means that cuts the fuel when overcharging exceeds the limit supercharging pressure. The engine boost pressure control device is configured to include means for reducing the boost pressure control means in the vicinity of the operating state when an overcharged state occurs.

As a result, even in a system that performs fuel cant during over-supercharging, when the over-supercharging state occurs, the supercharging pressure control amount in the vicinity of the operating state is reduced, so the over-supercharging state occurs intermittently. This has the effect of reliably preventing damage to the engine and exhaust system due to repeated intermittent fuel cuts.

[Brief explanation of drawings]

1 to 5 show one embodiment of the present invention. FIG. 1 is an overall configuration diagram showing a boost pressure control device for a supercharged engine. FIG. 2 is a flowchart of boost pressure control. FIG. 3 is a flowchart 1 for detecting an overcharging pressure state and performing correction control. FIG. 4 is a timing chart of the same control operation. FIG. 5 is an explanatory diagram showing a target boost pressure characteristic map. FIG. 6 is an explanatory diagram of the conventional operation in an overcharging pressure state. 1 1 is a rotary piston engine (supercharger engine), 2 is an intake passage, 3 is a blower, 4 is an exhaust passage, 5 is a turbine, 10 and 11 are fuel injection valves, 15 is a control unit, 21 is A waste gate valve, 24 is a duty solenoid valve, and 29 is a boost pressure sensor.

Claims (1)

[Claims] 1. A supercharging system comprising a supercharging pressure control means that controls the supercharging pressure according to the operating state of the engine, and a fuel control means that cuts fuel when overcharging exceeds the limit supercharging pressure. A supercharging pressure control device for a supercharged engine, characterized in that the supercharging pressure control device for a supercharged engine is provided with means for reducing a boost pressure control amount in the vicinity of an operating state when an over-supercharging state occurs. Boost pressure control device.