RU2242733C2 - Method to determine phase of working cycle of internal combustion engine - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to internal combustion engines with distributed injection of fuel. Proposed method of determination of phase of working cycle of multicylinder internal combination engine with distributed group injection of fuel with measuring of angular velocity of crankshaft includes measuring of average value of angular velocity, deviation of angular velocity from average value and maximum value of deviation of angular velocity from average value. Test injection of fuel into one of cylinders is done, and working stroke of said cylinder is determined by excess of deviation of angular velocity relative to maximum value.

EFFECT: possibility of determination of working cycle phase at no (vanishing) signal phase sensor.

3 cl, 2 dwg

Description

The invention relates to engine building and can be used to control an internal combustion engine (hereinafter - ICE) with distributed fuel injection.

Known internal combustion engines with distributed cyclic group fuel injection into the intake tract. The fuel injection control system includes a crankshaft position sensor, a controller made on the basis of a microcomputer, and fuel injectors. Fuel injection is carried out simultaneously by all fuel injectors (1) or in parallel-pairwise (2). Fuel injection is carried out by turning on the fuel injectors in a predetermined rotation phase (angular position) of the crankshaft for a certain. time dependent on the internal combustion engine operating mode, determined by processing the signal from the crankshaft position sensor.

Since the full ICE cycle is carried out in two rotations of the crankshaft (720 angular degrees or 4π radians), the angular position of the crankshaft does not provide accurate information about the phase of the working process. The angular position of the crankshaft allows you to accurately determine the phase of movement of the piston from top dead center to bottom dead center and from bottom dead center to top dead center, however, it is not known what working cycle is accomplished in this case: working stroke or intake, or, respectively, compression or release.

Known (3) control system of internal combustion engines with distributed sequential fuel injection, equipped with an additional camshaft position sensor (phase sensor). The signal of the phase sensor, which is formed in a particular case at the end of the compression stroke of the first cylinder, in conjunction with data on the position of the crankshaft, allows you to determine the phase of the ICE duty cycle. Using the signal of the phase sensor and the signal of the sensor for positioning the crankshaft, the controller calculates the moments when the nozzles are turned on so that the injection for each cylinder is carried out in a certain phase of the duty cycle (for example, on a closed intake valve before the start of the intake stroke), which allows to increase the effective performance of a specific ICE . The duration of the nozzles, which determines the amount of fuel supply, is calculated based on the operating mode of the internal combustion engine, including the angular speed of rotation of the internal combustion engine crankshaft, which is determined by measuring the time the shaft rotates through a given angle, for example, equal to the n-th part of the full duty cycle Ф = 4π / n, where n is the number of ICE cylinders.

The disadvantages of this system are the increased complexity and cost, due to the presence of a phase sensor in the system and additional wiring for connecting the sensor to the controller.

The disadvantage of the method for determining the phase of the internal combustion engine cycle is the complexity of the hardware implementation, due to the need to use a phase sensor.

A known method for determining the phase of the internal combustion engine cycle (patent RU2170915, publ. 07/20/2001), in which test injections of reduced or increased amounts of fuel into one of the engine cylinders is performed, time values of the internal combustion engine are measured and compared to each other in time rotation of the crankshaft by a predetermined angle and determine the phase of the working process by changing the rotation time by a predetermined angle compared with the time corresponding to the previous measurement. The disadvantage of this method is its limited use.

The prototype of the proposed method is a method for determining the phase of the ICE duty cycle with distributed fuel injection, used in a control system equipped with a phase sensor.

The task of the invention is to determine the phase of the internal combustion engine in the absence (loss) of the phase sensor signal. This problem is solved by the fact that in the method for determining the phase of the working cycle of a multi-cylinder internal combustion engine with distributed group fuel injection, including measuring the angular velocity of the crankshaft, determine the average value of the angular velocity, the deviation of the angular velocity from the average value and the maximum value of the deviation of the angular velocity from the average value, test injection into one of the cylinders and determine the stroke of the stroke of the cylinder by exceeding the deviation of the angular velocity relative to the maximum beginnings.

Determination of the stroke of the stroke can be made at the steady state operation of the internal combustion engine. Simultaneously with test injection, metered fuel injection into the remaining cylinders can be performed.

In the mode of group fuel injection into the inlet tract of an n-cylinder four-stroke engine, a sequence of values of the angular velocity Ω of the engine crankshaft rotation at an angle Ф <= 4π / n (determined experimentally) is measured, the average value of the angular velocity ΔΩ _av is determined, the maximum deviation ΔΩ _{max is} determined angular velocity Ω from the average value of _{av av} and test injection of reduced / increased amount of fuel into one of the internal combustion engine cylinders. After the test injection, they continue to measure the values of the angular velocity Ω of the engine crankshaft rotation through the angle Ф and determine the values ΔΩ = Ω-Ω _{av of the} deviation of the angular velocity Ω from the average value of _{av av} . The obtained values of ΔΩ and ΔΩ _{max are} compared, and if Ω _av > ΔΩ _max is exceeded, it is determined that the angular sector Φ of the crankshaft rotation, in which the deviation of the angular velocity exceeds the maximum value ΔΩ _max, belongs to the stroke of the cylinder stroke for which the test injection was performed.

The maximum value ΔΩ _max deviations from the average value of _{av av} is determined either immediately before the test injection, or in advance, at the stage of testing (calibration) of the internal combustion engine.

In the first case, for example, a sequential measurement and summation of K (experimentally determined) of the values of the rotation speed Ω of the ICE crankshaft by the angle Ф is carried out and divided by the number K, thus obtaining the average value of _{av av} . The values ΔΩ = Ω-Ω _{av of} deviations from the average value of Ω _{av are} determined. The ΔΩ _max value is determined by sorting the ΔΩ values.

In the second case, the value ΔΩ _max for each high-speed engine mode, i.e. for each value of Ω _av , determine at the stage of testing the internal combustion engine and write to the read-only memory of the controller microcomputer. Before the test injection, a sequence of values of Ω is measured, the average value of Ω _av is determined and the corresponding value ΔΩ _{max is} extracted from the memory.

The described procedure for determining the phase of the working process is carried out at an established high-speed mode of operation of the internal combustion engine.

As a criterion for the steady-state working process, the condition for limiting the instability of the shaft rotation speed at a given level ΔΩ <ΔΩ _ad , where ΔΩ _ad is the deviation ΔΩ acceptable for the steady state (experimentally determined), can serve as a criterion.

In an embodiment of the proposed method for determining the phase of the internal combustion engine operation cycle in the internal combustion engine operation cycle, in which a test injection of, for example, a reduced amount of fuel for one of the n cylinders is performed, a metered injection of an increased amount of fuel for the remaining cylinders is performed. This can achieve three goals:

- firstly, to avoid, albeit a small, drop in the average angular speed of rotation of the motor shaft in this cycle;

- secondly, to ensure the preservation of the average stoichiometric composition in the operating cycle that is optimal for the operation of the exhaust gas aftertreatment system:

- thirdly, when repeating this test cycle, to accelerate the heating of the neutralization system as a result of the presence in the exhaust gas of a mixture of unreacted oxygen and hydrocarbons, the reaction of which with the evolution of heat occurs on the catalyst of the neutralization system.

On the contrary, in the ICE cycle. in which a test injection of an increased amount of fuel for one of the n cylinders is performed, a metered injection of a reduced amount of fuel for the remaining cylinders is performed.

Determining the phase of the duty cycle for one of the cylinders of a four-stroke ICE allows you to uniquely determine the phases of the duty cycle for all other cylinders of the ICE, which is due to the design of the ICE. The operation of a four-stroke internal combustion engine is a rigid periodic sequence of cycles of the working process (intake, compression, stroke, exhaust), therefore, a single determination of the current phase of the internal combustion engine and measurement of the position of the crankshaft allow you to know the current phase of operation of each cylinder in all subsequent operation cycles until the internal combustion engine stops.

The inventive method allows for sequential injection of fuel into the internal combustion engine while maintaining effective performance when the phase sensor fails (if the system is equipped with such a sensor), which increases the reliability of the system. The method allows for sequential fuel injection into the internal combustion engine in the absence of a phase sensor in the control system, which simplifies it and, therefore, increases reliability due to simplification, and also reduces the cost of the system.

The invention is illustrated by the following drawings.

Figure 1 shows the structural diagram of the control system of the engine for the implementation of the proposed method.

Figure 2 shows the nature of the change in angular velocity ω = dφ / dt of the ICE crankshaft, where φ is the angle of rotation of the shaft; t is the current time.

The example shows a control system for a four-cylinder internal combustion engine (n = 4), but the method is feasible for an engine with any number of cylinders.

In figure 2 there are the following notation:

φ _av is the average angular velocity of rotation of the crankshaft by an angle Ф <= 720/4;

ω _a is the amplitude value of the pulsations of the angular velocity caused by pulsations of pressure in the cylinders of the engine;

+ Δω - change in the amplitude value of the angular velocity caused by test injection with an increased amount of fuel;

-Δω - change in the amplitude value of the angular velocity caused by test injection with a reduced amount of fuel.

Figure 2 does not take into account the instabilities of the workflow, so as not to complicate the description. Processing information about the operation of a real internal combustion engine requires the experimental determination of threshold calibration constants, depending on the design features and operating mode of the internal combustion engine.

The inventive method can be implemented in an internal combustion engine control system (see Fig. 1), including a controller 1 made on the basis of a microcomputer, a crankshaft angular position sensor 2 connected to the input of the controller 1, and fuel injectors 3 connected to the outputs of the controller 1.

The system may also contain other sensors of the internal combustion engine operation mode, such as air flow sensor 4, throttle position sensor 5, coolant temperature sensor 6, etc., connected to the corresponding inputs of controller 1.

The sensor 2 can be made, for example, in the form of a magneto-induction sensitive element placed above a gear disk made of ferromagnetic material, rigidly mounted on the crankshaft of the ICE and having 60-2 teeth, the position of the missing teeth relative to the TDC is determined.

To implement the method perform the following steps.

In the scroll mode of the engine using the starter (start mode), the crankshaft angular position sensor 2 generates electrical impulses that accurately determine the angular position of the shaft relative to the top dead center (TDC).

The controller 1 of the control system by the signal of the sensor 2 determines the current position of the engine crankshaft relative to TDC.

Using the signals of the sensor 2 (4, 5, 6), the controller 1 performs pairwise-parallel (group) fuel injection control by opening the nozzles 3 of the corresponding pairs (1-4 and 3-2) of the cylinders in a certain angular position of the crankshaft.

The controller 1 produces a sequence of measurements of the angular velocity Ω of the rotation of the crankshaft of the engine at an angle F.

When the ICE crankshaft reaches a certain value of the angular speed of rotation, a conclusion is drawn about the end of the starting mode.

The value of ΔΩ _max . To do this, find the maximum value of the deviation ΔΩ from the average Ω _av by the sorting method. The found maximum deviation value can be corrected, for example, by multiplying by a coefficient empirically determined.

Write the value ΔΩ _max in the memory of the microcomputer of the controller 1.

In an embodiment, can calculate the amount of deviation ΔΩ Ω _av from Ω _av, and check on the implementation of conditions ΔΩ <ΔΩ _ad, whether the internal combustion engine steady operation.

A test injection of a reduced or increased amount of fuel is carried out in one of the cylinders, for example, in the first cylinder of the internal combustion engine.

In an embodiment of the inventive method, they can also conduct a modified fuel supply to the remaining cylinders in the cycle of the internal combustion engine with test injection. Moreover, if the test fuel injection for the first cylinder is increased, then for the remaining cylinders a reduced amount of fuel is injected, and vice versa, the test injection of a reduced amount of fuel for the first cylinder is accompanied by an increased fuel supply for the remaining cylinders.

After the test injection, the controller 1 continues to measure the angular velocity Ω, determine the deviation ΔΩ, and compare the latter with ΔΩ _max recorded in the memory of the microcomputer of controller 1.

After the test injection, ΔΩ is compared with ΔΩ _max in the angular sectors Φ until then. until the condition ΔΩ> ΔΩ _max .

They determine how the working stroke of the first cylinder, the ICE operation cycle, to which the angular sector Φ of the crankshaft rotation belongs, the deviation of the angular velocity at which ΔΩ> ΔΩ _max .

Determine the phase of the internal combustion engine workflow.

To increase the reliability of determining the phase of the ICE duty cycle, the above procedure can be repeated several times.

After that, the controller performs sequential fuel injection, in which the nozzles are turned on in accordance with the order of operation of the internal combustion engine cylinders. Fuel injection for each cylinder is carried out in a certain phase of the working process, for example, for an internal combustion engine of a VAZ-2112 car, fuel is injected onto a closed intake valve before the start of the intake stroke. The phase and duration of the injection are calculated by the controller according to the results of measuring the parameters of the internal combustion engine operation mode.

The proposed sequence of actions allows you to determine the phase of the internal combustion engine without processing the signal from the phase sensor. This simplifies the structure and cost of the engine control system and increases its reliability.

Literature

1. Cars VAZ-21083, VAZ-21093, VAZ-21099, VAZ-21102, VAZ-2111. Engine control system VAZ-2111 (1.5 L) with distributed fuel injection. Maintenance and repair manual. - M .: "Livre", 1998, p. 11.

2. Engine control system VAZ-2111 and VAZ-2112 (1.5 L) with distributed fuel injection. Maintenance and repair manual. - M .: "The Third Rome", 1999, p. 15 and 16.

3. Ibid., Pp. 158 and 159.

Claims (3)

1. The method of determining the phase of the working cycle of a multi-cylinder internal combustion engine with distributed group fuel injection, including measuring the angular velocity of the crankshaft, characterized in that they determine the average value of the angular velocity, the deviation of the angular velocity from the average value and the maximum value of the deviation of the angular velocity from the average value, produce a test injection into one of the cylinders and determine the stroke of the stroke of the cylinder by exceeding the deviation of the angular velocity relative to the maximum value. 2. The method according to claim 1, characterized in that the determination of the stroke of the stroke is carried out at the steady-state mode of operation of the internal combustion engine. 3. The method according to claim 1, characterized in that at the same time as the test injection, a metered fuel injection is made into the remaining ICE cylinders.

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