RU2677025C1 - Method for controlling internal combustion engine during its operation - Google Patents

Abstract

FIELD: engines and pumps.SUBSTANCE: invention can be used in control systems of internal combustion engines (ICE). In the proposed method the air flow is regulated by a throttle from a driver's pedal. According to the signals of limit switches, the position of idling and the position of the throttle valve switch the Pulse Width Modulator (PWM) modes of the Electronic Control Unit (ECU) by engine operation. PWM ECU generates a pulse to the fuel injection nozzle synchronously with the working position of an engine shaft with duration proportional to the absolute static air pressure in an intake channel. Depending on the operation mode of the engine, the ECU switches, and from a cab, a driver adjusts the proportionality coefficients of the air-fuel ratio in the PWM: when idle, the proportionality factor is set at the maximum frequency of the idling speed, during acceleration, the proportionality coefficient is set upon reaching the selected acceleration and, with uniform motion, the proportionality coefficient is determined by limiting the power and speed of movement without the possibility of exceeding it.EFFECT: selection of the required engine power for movement and fuel economy.1 cl

Description

The invention relates to engine building and can be used in vehicles for regulating an injection Internal Combustion Engine. The engine is equipped with a throttle that controls the air supply to the inlet and is controlled by a cable from the driver’s pedal. The electronic engine control unit generates, synchronous with the working position of the engine shaft, a pulse of variable duration to the fuel injection valve in the working area, proportional to the absolute static air pressure in the inlet channel. The start-up and idle, acceleration and uniform operation of the engine are determined by the computer using the signals from the working sensors, which regulates the air / fuel ratio in the combustible mixture and the amount of the mixture in the engine, supporting typical parameters of the economy and power of the internal combustion engine during operation. However, typical control parameters of serial engines stored in the ECU microcomputer memory are generalized to the scatter of engine parameters in a large batch of output. This limits the adaptation of an individual ICE to specific operating conditions, increases fuel consumption and underestimates the possible power.

The well-known "Method of regulating the power of an internal combustion engine with external mixture formation and a device for its implementation" according to copyright certificate SU 1677359, IPC F02D 41/02, 35/00, 28/00. The method includes measuring the engine shaft speed in a digital code, measuring the vacuum in the intake manifold, calculating the effective torque on the engine shaft, comparing it with a given moment from an external driver and adjusting the angle of the throttle position using a controlled drive. In this case, the correction is carried out according to the control tabular data of the speed characteristics recorded in the device memory and related to this type of engine. However, a method using this table is not effective when changing the conditions of external mixture formation and the influence of uncontrolled factors (engine wear, fuel quality and composition, air composition, etc.). Consideration of a greater number of influencing factors on the operation of the engine is possible by equipping it with additional sensors associated with an ECU based on a microcomputer that controls electromagnetic actuators. An exemplary set of sensors and actuating control devices for an internal combustion engine is given in the description of the invention to the patent “Fuel injection device and method for controlling it” RU 2434158 C2, IPC F02D 41/40. The device contains sensors for the accelerator, the opening angle of the throttle, the speed and position of the crankshaft of the engine, the pressure and air flow rate in the inlet channel, the temperature of the engine and exhaust gas, the composition of the exhaust gas, etc., as well as the fuel injection solenoid valves, the electric actuator for controlling the opening angle inlet throttle etc. The disadvantages of this method of engine control include the complexity of the hardware and software complex for highlighting the parameters of the transient acceleration mode, the need for duplication for the reliability of the sensors and equipment responsible for the safety of the movement, the complexity of the ECU tuning by specialists. Operational adjustment in the field of a specific engine ECU during operation is not provided. In case of faulty sensors and equipment malfunctions, the microcomputer control system switches to emergency operation, which does not guarantee fuel economy, sufficient ICE power during operation.

There is a tendency to complicate the measurement methods and devices for obtaining pressure data in the inlet window of the working cavity in order to increase the accuracy of air charge measurements taking into account the dynamics of filling and calculation accuracy for controlling the engine operation in the transient acceleration mode, described in the description of the invention “Data acquisition method (options) and system for recording pressure data in the inlet window of the cylinder ”to patent RU 2584747, IPC F02D 9/02, F02D 41/18, F02D 41/22. However, more accurate measurements and calculations using typical speed characteristics and functions are not correct for an engine with a certain wear, running on fuels that differ in quality and in conditions that are not quite consistent with typical ones. This forces the manufacturer to equip ICE with increasingly sophisticated control systems. At the same time, the cost of production, maintenance and repair of systems increases.

The known method used when duplicating control in the invention according to the patent "Engine Management System" RU 2267021 C1, IPC F02D 11/02, having a standard and emergency diesel control system. The standard control system contains sensors, a control microcomputer, an electromagnetic drive for positioning the fuel rail. When the standard control system fails, the emergency system is turned on. The emergency control system contains a spring-loaded membrane pneumatic actuator for the position of the fuel rail. The pneumatic actuator is connected by a pipeline to the vacuum cavity behind the air damper, which is installed at the inlet to the turbocompressor. The air damper is connected through the emergency mode enable mechanism to the control pedal. In the invention, a method is used that includes the selection of the vacuum behind the air damper and transmission through the pipeline to a spring-loaded diaphragm pneumatic actuator, which, by moving the fuel control rail, maintains engine speed according to the given position of the air damper from the control pedal. The disadvantage of this emergency control system is the use as a control parameter of the vacuum behind the air damper installed at the inlet to the turbocharger. The specified vacuum does not correspond to the actual filling of the engine working cylinder with air. There is also no operational correction of the air / fuel ratio for various engine operating modes.

The closest analogue of the invention is the "Method of controlling an internal combustion engine depending on operating conditions" according to the application for the invention RU 2013122001 IPC F02 43 | 00. The method includes synchronizing the operating position of the engine shaft with fuel metering proportional to the absolute air pressure in the inlet channel, which is regulated by a throttle valve from the driver’s pedal. The proportionality coefficient is adjusted depending on the operating conditions at the request of the driver, however, objective signs and actions during correction, which are reflected in the power and efficiency of the engine, are not indicated.

The aim of the invention is a method of controlling the internal combustion engine, taking into account the correction of the proportionality of the duration of the fuel injection to the absolute static air pressure in the inlet channel according to objective indicators of engine power and economy during operation.

The theoretical basis of the proposed method.

When communicating with the inlet of the combustion chamber of the engine, the working mass of air in the combustion chamber is determined by the absolute static air pressure in the inlet channel, which occurs after throttling the air flow by the damper. The mass of air received at the intake phase into the combustion chamber is determined from the equation of state of an ideal gas.

where M is the mass of air in the working volume of the combustion chamber;

P - absolute static air pressure in the inlet;

V is the working volume of the combustion chamber;

T is the absolute temperature of the air;

R is the gas constant.

The mass M of air in the working volume of the combustion chamber is proportional to the absolute static pressure P of the air in the inlet channel.

The dosed mass of fuel, for example a nozzle, into the working volume V of the combustion chamber can be determined from the expression

, где

where

m is the mass of the dose of fuel;

q is the density of liquid fuel;

s is the working section of the fuel nozzle outlet;

u is the fuel speed at the outlet of the nozzle;

t is the fuel dosing time.

The fuel pressure at the nozzle inlet is usually kept constant by a pressure regulator.

It is known that the greatest power and economy of the engine is achieved when working on a combustible mixture having a stoichiometric ratio of air / fuel in the cylinder. Power, for example, for a four cylinder ICE is ideally determined by the expression

, где

where

N is the power of the internal combustion engine;

Q - thermal energy of the air / fuel mixture in the combustion chamber

C - specific caloric content of the air / fuel mixture

M is the mass of air in the cylinder;

m is the mass of fuel in the cylinder;

M / m - stoichiometric ratio (constant value)

F is the engine speed;

The proportionality of the fuel mass to the absolute static pressure in the cylinder inlet by the known control method in the closest analogue of the invention is set according to the expression

, где

where

k is the coefficient of proportionality;

P - absolute static air pressure in the inlet;

Substituting expression (4) for mass m into equation (3), we obtain the equation for power N in the form

Further, replacing the mass of air M in equation (5) by the gas state equation (1), we obtain the dependence of the engine power according to equation (6),

from the product PF and the given structural - thermophysical coefficient 2Ck (V / RTk + 1), which is constant at a constant temperature T of the incoming air and the established proportionality coefficient k.

The product PF characterizes the pumping function of the engine - the intake of throttled air into the inlet channel and the filling of the working volume of the cylinder with air. The absolute static pressure P of the air in the inlet depends on the frequency F of the movement of the piston of the suction air and the opening angle of the throttle for air intake. Air throttling reduces the absolute static pressure P of air in the inlet channel and the mass m of air in the cylinder at any engine shaft speed. The pump function PF and therefore engine power N have a maximum at medium crankshaft speeds with the throttle open. At low speeds of the shaft rotation, the filling of the cylinder increases, but due to the low speed of rotation of the crankshaft, the internal combustion engine power decreases. On the other hand, with a high speed of rotation of the crankshaft, the cylinder does not have time to fill with air and engine power is reduced. This is confirmed experimentally by the technical characteristics of production cars with an indication of the maximum power at engine speeds of rotation of the crankshaft that are below the maximum allowable. For example, the power of the RP engine of a Volkswagen Golf 2 is 66 kW at 5200 rpm with a maximum frequency of 6200 rpm.

During engine operation, the maximum pump function PF of the frequency F of the crankshaft speed is manifested in the maximum power N of the engine supporting this frequency F of revolutions. Maximum engine power is achieved only when using an air / fuel mixture in a stoichiometric ratio. Deviation of the air / fuel mixture from the stoichiometric ratio leads to heat loss due to heating of excess air or fuel and a decrease in engine power and crankshaft speed. The rotational speed of the crankshaft is an objective indicator of engine power at constant load.

In idle mode with a constant throttle position, by adjusting the proportionality factor to the stoichiometric ratio, increase the crankshaft speed to maximum. Next, by reducing the air supply throttle set the nominal idle speed.

In the mode of uniform movement with a constant position of the throttle, by adjusting the proportionality coefficient to the value of the stoichiometric ratio, increase the crankshaft speed to a maximum and corresponding to a given speed limit.

In the acceleration mode, a proportionality coefficient is used in the range of possible settings from the proportionality coefficient at XX (economy mode) to the proportionality coefficient at maximum engine power with the throttle fully open (sports mode) upon reaching the required acceleration.

Operating the engine at frequencies higher than the crankshaft speed at maximum power with the throttle fully open leads to reduced power, increased fuel consumption and additional engine wear.

The electronic engine control unit by the signals of the working sensors switches the proportional factors corrected to the stoichiometric ratio during idling, acceleration and uniform movement. Regulation of engine power with a stoichiometric air / fuel ratio is carried out as usual by changing the air supply to the inlet channel with a throttle valve controlled by a cable from the driver’s pedal.

The proposed method is implemented on a Volkswagen Golf 2 car with an injection ICE as a single injection. The intake channel of the internal combustion engine has a nozzle for fuel injection and a throttle valve spring-loaded to return, controlled by a cable from pressing the driver’s pedal. The electric drive of the XX position of the throttle valve and the position of the limit switch XX has been replaced by a flexible shaft for manual drive from the driver's cab.

The cavity of the air inlet channel is connected to a fast-acting (100% scale mileage in 2 ms) strain gauge Absolute Air Pressure type GAZ 745.3829 (Russia). The output voltage of the DBP is fed to the control input of the known (description of the invention to patent RU No. 2107179 "Device for controlling the supply of fuel to the internal combustion engine", Fig. 2). A pulse-width modulator of the ECU, which converts the DBP signal into an electric pulse proportional in duration to turn on the fuel injector. PWM is synchronized by the signals of the Hall sensor according to the ignition timing during rotation of the motor shaft. The proportion of the conversion of the DBP control voltage at the input to the PWM ECU to the pulse width at the output of the PWM ECU to control the fuel supply to the injector also depends on the timing of the correction resistor in the integrated resistive-capacitive circuit of the PWM ECU. The XX operating modes, acceleration and uniform movement are determined by the ECU according to the signals of the working sensors - the limit switch of the XX throttle position and the “acceleration” limit switch, which is triggered by the pressure of the slider, which is frictionally connected with the throttle cable. As a limit switch for the friction slider, a micro switch type MP9-P1 (Russia) is used, which is mounted on the bracket of the mono-injection unit near the throttle valve. The movement of the friction slider is limited by the operating zone of the actuation of the “acceleration” limit switch. By the signals of the limit switches, the ECU switches the time-consuming correction resistors in the integrated resistive-capacitive circuit of the PWM mode XX, accelerated and uniform movement. Timing correction resistors are installed in the driver's cab on the dashboard. The crankshaft speed counter is also located on the dashboard of the driver of a Volkswagen Golf 2 serial car.

The proposed "Method of regulating an internal combustion engine during operation" works as follows. When the engine is working, the Hall sensor of the crankshaft working position sends a control voltage pulse to the switch of the engine ignition system, the amplified pulse from the switch is fed to the computer, differentiated and the nozzle is turned on with the front of the pulse and simultaneously the capacitor charge the PWM resistive-capacitive circuit to the value of the control voltage from DBP. At the end of the capacitor charge, the electronic nozzle control key is closed. The time for charging and turning on the nozzle for fuel supply is proportional to the absolute air pressure in the inlet channel of the internal combustion engine and also depends on the value of the correcting time-setting resistor in the integrated charge circuit of the capacitor.

The air supply to the engine is regulated by pressing the driver’s pedal through the movement and tension of the cable and changing the position of the throttle valve spring-loaded to return to the inlet of the combustion chamber. The ECU, based on the signals of the limit switches XX and the “acceleration” of the throttle valve, determines the engine operation mode (XX, acceleration or uniform movement) and connects the correcting time-setting resistor of the integrated capacitive circuit to the PWM corresponding to each mode.

When starting and operating the engine at XX with the correction of the time-setting resistor XX, the working proportionality coefficient XX is set at the maximum rotational speed of the crankshaft. This adjustment eliminates fuel overrun by XX.

In acceleration mode, the driver is able to adjust the value of the acceleration resistor from the value at XX to the value at the maximum engine speed at maximum power with the throttle fully open. The working coefficient of proportionality of the “acceleration” is established upon the achievement of the required acceleration. In this case, the engine speed should not exceed the maximum engine speed at maximum power with the throttle fully open according to the fuel economy condition.

At the end of acceleration, the driver, by a non-significant return of the control pedal, turns off the “acceleration” limit switch and the ECU puts the engine into uniform operation mode.

With uniform motion, the time-consuming correction resistor is set to the working proportionality coefficient of uniform motion at maximum power and at maximum speed, ensuring compliance with a given speed without the possibility of exceeding it.

Thus, a method for regulating an internal combustion engine during operation is proposed, which includes adjustable air supply to the inlet channel by a throttle valve controlled by a cable from the driver’s pedal, fuel supply by the nozzle synchronously with the working position of the engine crankshaft and with a duration proportional to the absolute static air pressure in the intake channel, correction proportionality during operation. In the proposed method, experimentally set the working coefficient of proportionality of idling at the maximum frequency of revolutions of idle, then experimentally set the working coefficient of proportionality when accelerating upon reaching the desired acceleration, then experimentally set the working coefficient of proportionality with uniform movement, providing a given speed without exceeding it .

Regulation of engine power when operating at working proportionality coefficients with a stoichiometric air / fuel ratio is produced as usual by changing the air supply to the inlet channel with a throttle controlled by the driver’s pedal. At the same time, the Electronic Engine Control Unit, based on the signals of the working sensors, switches the corrected working proportional ratios during idling, acceleration and uniform movement during throttle movements.

Fuel economy is determined by the lower value of the correcting time-setting resistor and, accordingly, the shorter dosing time of the mass of fuel into the working cylinder.

The advantage of the proposed method of regulation is fuel economy in all modes of engine operation during operation.

Claims (1)

A method of regulating an internal combustion engine during operation, including an adjustable air supply to the inlet channel by a throttle valve controlled by a cable from the driver’s pedal, fuel supply by the nozzle synchronously with the working position of the engine crankshaft and with a duration proportional to the absolute static air pressure in the inlet channel, proportionality correction for operation, characterized in that experimentally establish the working coefficient of proportionality of idling at max the maximum idle speed, then experimentally establish the working proportionality coefficient when accelerating upon reaching the required acceleration, then experimentally set the working proportionality coefficient with uniform movement, providing a given speed without the possibility of exceeding it.