SU1183703A1 - Method of regulating internal combustion engine - Google Patents

Abstract

METHOD OF REGULATING INTERNAL COMBUSTION ENGINE by measuring each time interval, calculating the value of instability of the crankshaft rotation as a difference of values determined in two adjacent intervals, measuring the engine load and shaft rotation frequency, determining the reference level of instability, measuring the difference between the unit, its value and its value of its value. , generating a control signal for this difference to eliminate it, analyzing the composition of the exhaust gases and in case of its deviation from a stoichiometric mixture, generating a command signal to restore it, which, together with the control signal, affect the fuel supply and the amount of recirculated exhaust gases, and the command signal affects the fuel control authority, and the control signal controls the amount of recirculated exhaust gases, characterized in that, in order to improve the adjustment process, the duration of the duty cycle is taken as the time interval The accelerators determine the acceleration of the shaft rotation in each working cycle and as the difference of the values determined during two adjacent working cycles. Acceptance (L is the difference of the obtained accelerations, after which, taking into account the amount of recycled exhaust gases, the ignition advance angle is corrected. EnuHz jSfH / H, 00 00 o with

Description

The invention relates to the field of regulation of internal combustion engines, in particular to the regulation of light fuel engines, including pre-combustion ignition.

There is a method of controlling the internal combustion engine by measuring each time interval, calculating the value of crankshaft rotation instability as the difference of values determined in two adjacent intervals, measuring the engine load and shaft rotation frequency, determining the reference level of instability, measuring the difference between the current value and the reference level instability, generating a control signal for this difference to eliminate it, analyzing the composition of the exhaust gases and, if it is rejected from the composition corresponding to the stoichiometric mixture; one.

In this method, the rotation period of the crankshaft is selected as the time interval, and the instability is defined as the difference between two consecutive time intervals, i.e. the difference between two consecutive periods of shaft rotation. This determines that, with the instability adopted as the difference of two successive periods of rotation, the failure of one of the cylinders of a multi-cylinder engine causes a false signal of considerable magnitude and, therefore, significantly reduces the quality of regulation. In addition, with the instability adopted as the difference of two consecutive time intervals, the regulation of recirculation is possible only at steady-state speeds of engine operation. In the unsteady speed regimes, the difference between the current value and the reference level of instability, having a small amplitude and equal sign; cannot be detected against the background of a regular and significant change in the frequency of rotation of the shaft.

The disadvantage of the method is also that it does not reflect the necessity of correcting the ignition advance angle in terms of the amount of recycled exhaust gases.

The purpose of the invention is to improve the regulatory process.

For this purpose, the duration of the operating cycle of the engine is taken as the time interval, the acceleration of the shaft rotation in each working time is determined.

the cycle and as the difference of the values determined during two adjacent cycles, take the difference of the obtained accelerations, after which, taking into account the amount of recirculated exhaust gases, the ignition advance angle is corrected. FIG. Figure 1 shows the dependences of the specific fuel consumption gt on the excess air ratio in the absence of exhaust gas recirculation (a) and at

0 availability of recirculation and correction of the ignition advance angle (b); on. FIG. 2 - family of dependences D (P) (d changes in load and shaft rotation frequency in time (g), values of the reference level

instability and the difference between the current value and the reference level of instability (e), the dependence of the amount of recycled exhaust gases as a percentage of the total amount of exhaust gases over time (e); in fig. 3 -

0 linear variation of the frequency of rotation of the shaft in time and its increment due to instability; in fig. 4 - approximation of the acceleration curve; in fig. 5 is a simplified functional diagram for implementing the method.

Accept also the following designations: P - engine load; n is the frequency of rotation of the engine shaft; Lp - increment of shaft rotation frequency due to regular changes, bp - increment of frequency

Q shaft rotation due to instability; T - the duration of the operating cycle of the engine; And - instability of rotation of the engine shaft; A / is the current value of rotational instability, A on is the reference level of rotational instability; a - coefficient of excess air; 0 is the ignition advance angle; 6 opt-B - the optimum angle of advance in the recirculation of exhaust gases; g, is the specific fuel consumption; geMHH. - the minimum specific fuel consumption in the absence of recirculation, in the mode of efficient depletion of the mixture, -) - the specific fuel consumption in the absence of recirculation at ° C 1; gtwiW2 is the minimum specific fuel consumption in the presence of recirculation and correction of the ignition advance angle and Ots% is the amount of recirculated exhaust gases as a percentage of the total amount of exhaust gases.

The simultaneous regulation of the recirculation and fuel supply at the correction of the ignition advance angle (Fig. 1) is carried out to ensure the operation of a three-way catalytic converter that drastically reduces the level of all major toxic components, but requires the stoichiometric composition of the mixture (a 1) and to simultaneously ensure maximum These conditions are engine efficiency.

In the absence of recirculation (curve a), the minimum specific fuel consumption does not correspond to the stoichiometric composition of the mixture (od 1), but to the lean mixture, and in the effective depletion mode, it is equal to ge gtntfHi, T.-e. SVo decrease is approximately 6% and is reflected by the value of g geM «« i

Therefore, the use of a three-way catalytic converter always leads to a deterioration of the efficiency of the engine.

If exhaust gas recirculation is applied, i.e., dilution of the working mixture with these gases (curve b), then with a certain intensity of recirculation and a corresponding correction of the ignition advance angle, partial compensation of deterioration of economy (approximately 3%) can be achieved, ensuring the minimum specific fuel consumption at all speeds modes ge This corresponds to the effective dilution of the mixture with exhaust gases.

The proposed method is a combination of two methods implemented at all speeds by two control systems, interconnected by a reference level of instability of ruling, when exposed to a third system, the ignition system.

One of the systems maintains the state of the control object on line A (Fig. 1), the stabilization system), the other on line B (the recirculation control system with the ignition angle correction). In case of joint control by two systems, the state of the control object is reflected by point C. In the stabilization system, a command signal is generated, in the control system, a control signal is generated.

The process of stabilization of the stoichiometric mixture, i.e., the maintenance of "1", is based on the fact that the composition of the exhaust gases is analyzed by a special sensor, for example, oxygen. If the composition of these gases differs from the composition corresponding to the stoichiometric composition of the mixture, the sensor generates a voltage on the basis of which a command signal is generated that acts on the fuel control unit, such as the carburetor solenoid valve. The command signal affects the composition of the mixture in such a way that the latter tends to be stoichiometric. Thus, the composition of the exhaust gases is analyzed and, if it deviates from the composition corresponding to the stoichiometric mixture, a command signal is generated for its recovery, which, together with the control signal, affect the fuel supply and the amount of exhaust gas recirculated,

the fuel supply control authority, and the controller for the control unit for the amount of recirculated exhaust gases.

The regulation of the recirculation is based on the fact that the magnitude of the instability of the rotation of the engine shaft D depends on the degree of recirculation of the exhaust gases at a given a and this ignition advance angle c. The task is to regulate recycling to ensure the effective dilution of the mixture with a stoichiometric composition, i.e. ensure compliance with the condition of ee.n kg at a 1 and if there is an optimum ignition angle 0 Qonr.-R.

In order to achieve the fulfillment of 5 of this condition in the course of operation, it is fulfilled during the experiment and, for example, a family of dependencies D (P) is obtained at different fixed values of the rotation frequency 0 i; “2; LZ with a 1, 0 Vpt.-K and ge geMKHa (a)

These dependencies are implemented in the corresponding permanent storage device of the control system and from them the instability is determined by the current values of n Ptu 5, at which the specified engine requirement is met, i.e. ge geHHHa at а 1 and Q 9opt-K - This value is the reference level of Aop instability and corresponds to a certain amount of recirculated exhaust gases, ensuring that the specified conditions are met.

The current value of instability 4 is maintained by regulating the recirculation near the reference level, thereby ensuring that the specified requirements are met. With the help of dashed lines (Fig. 2), the constructions are shown that clarify the definition of the reference level of instability Aop (g) using the current values of L and P (g) and the dependences A (P) (c). To simplify the construction of scientific research institutes, all the initial dependencies are shown in straight lines, although in reality their form can be quite complex. Chart e shows the change in the amount of exhaust gases Sc% as a percentage of the total amount of exhaust gases in 5 times in accordance with the reference level of instability.

The determination of the reference level of Aop instability is explained as follows. Point 1 marks the start of the timing in the adjustment process. In the time interval between points 1 and 2, the load P of the engine decreases, between points 2–4 remains constant, and between points 4–12 increases. The shaft rotation frequency in the time interval between points 1–3 is kept constant and equal to n, between points 3-b it decreases, between points 6 and 7 remains constant and equal to n nz, between points 7 and 8 it increases, between points 8-11 is reduced and between points 11 and 12 is kept constant and equal to pz. To determine the reference level Dop, the following constructions are made.

At the time point marked by point 1, the shaft rotation frequency is equal to n. Therefore, the value of P that occurs at this moment is projected on the dependence from the family A (I), which was obtained at g n (point 1; graph a). From point 1, the perpendicular p is omitted on the axis A and the value obtained from the horizontal axis D in the graph and transferred to the vertical axis D in the graph g. Then a horizontal line is drawn from this point and a vertical line from point 1. Their intersection, marked by point 1, is the value of the reference level of instability at the point in time, marked by point 1.

Similar constructions are made at the time points marked by points 2, 3, 6, 7, 11, and 12 and using the corresponding points 2, 3, 6, 7, P, and 12 obtain the values of the reference instability level 2, 3, 6, 7, and 12 on the graph g.

The constructions carried out at the time points marked by points 4, 5, 8, and 9 are characterized by the fact that at these moments the current shaft rotation frequency is not equal to any of the fixed values at which the dependences of the D (P) family are plotted on graph a, and illustrate the fact that from the family of dependencies D (P) they use the dependence obtained for a fixed value of n, which is closer to the current value of the rotation frequency. When determining the reference level Dop at specified times, another method can be applied, for example, the interpolation method.

The current value of the instability D; receive as follows.

The acceleration of the shaft rotation in each engine running cycle and the difference between the accelerations in two successive adjacent cycles are determined, and the smaller one is subtracted from the larger value. The latter is due to the fact that the reference level of instability, with which its current value of D / is compared, is a positive value.

In order to obtain a control signal, the difference between the current value and the reference instability level D / - Aq (plot g), which is an error signal in the control system, is measured. This signal is converted into a control signal fed to the actuator of the recirculation regulator acting on the recirculating control unit, which, in particular, may be an electrically controlled valve.

The impact is made in such a way that a change in the amount of recirculated exhaust gases leads to a decrease in the error signal, i.e., the current instability D tends to a reference level Dop corresponding to the fulfillment of the condition gewHHa at а 1 and 8 bop-K The considered process of regulating recirculation shows that the engine load and the shaft rotational speed are measured, the reference level of instability is determined, the difference between the current value and the reference level of instability is measured, and the difference which is a signal to eliminate it. The instability value is calculated as the difference of the values determined during two adjacent time intervals. In this case, the duration of the engine working cycle is taken as the time interval, the acceleration of the shaft rotation in each working cycle is determined, and the difference of the accelerations obtained is taken as the difference of the values determined during the two adjacent work cycles. The calculation of the instability of rotation allows the calculation of instability to eliminate the effect of regularly changing the frequency of rotation of the shaft at unspecified speed conditions, as well as the relatively low frequency cyclic fluctuations of the speed of rotation observed in the established speed modes. In addition, the effect on the quality of the malfunction adjustment of one of the cylinders of a multi-cylinder engine is reduced.

With the accepted degree of instability, the difference in the values determined during two adjacent cycles is equal in accordance with FIG. 3:

.i + LrL i

Ti

Ti

+ 1

; +2

Dp,

Lp,

Sni + iSni

t ± fii I / Oflj-H

i + i

),

ir) -IT (.

Tj + r tifi. Tt + i

where T, 1 and T, -f2 - the duration of adjacent work cycles;

Dp, and D "; + | - increment of rotational frequency, respectively, per cycle;

T / 4-1 and - due to regular changes;

b / g; ups, + | - irregular increments of the rotation frequency, respectively, over cycles TI + I and T | +2, due to the instability of the rotation.

With a linear change in the frequency of rotation, the first bracket vanishes and, therefore, the difference in the values determined during two adjacent cycles is instability and is equal to

D bpu | Bt

Ti + 2 Ti-tt

In general, the change in rotational speed is not linear. Typical of 71

Changes are displayed, for example, by the acceleration curve, which is approximately shown in FIG. 4. This curve can be approximated by straight line segments, as shown by the example of segments connecting points 13 and 15 and 14 and 16. Each of these segments covers parts of two adjacent cycles, during which the instability is calculated. In these areas, the variations in the rotational speed can be considered linear and, in connection with this, the latter formula can be used.

The validity of this approximation of the entire acceleration curve is confirmed by the following considerations. The approximate acceleration time of an automobile engine from 1000 rpm to 6600 rpm in one gear can be taken as 5 s.

The average number of revolutions of the shaft is 3800 rpm. about./s. Consequently, during the acceleration time, 315 revolutions take place, i.e., 157 duty cycles or approximately 78 pairs of cycles. Thus, the acceleration curve (Fig. 4) is approximated by 78 straight line segments, which is quite enough for the accepted assumption.

In order for the efficiency of the exhaust gas recirculation to increase to such values when the specific fuel consumption reaches the minimum values gg geHHHj, the ignition advance angle is corrected taking into account the amount of recycled exhaust gases, maintaining it at the optimum value of 9 seconds C - The amount of exhaust gas recirculated can be judged, for example, by the reference level of instability or by the magnitude of the control signal.

The simplified functional diagram (Fig. 5) shows the following elements: an oxygen sensor 17 for the composition of the exhaust gases, a command signal generating unit 18, an actuator for the regulator regulator of the stoichiometric composition of the mixture 19, a fuel regulating body, such as a carburetor 20 electronically controlled, an engine 21, load (dilution) sensor 22, crankshaft speed sensor 23, upper dead center sensor 24 (TDC). a reference instability level generating unit 25, a current instability calculating unit 26, a control signal generating unit 27, a recirculating regulator actuator 28, a recirculation control body 29 (recirculation valve), and an advance angle correction unit 30.

An exhaust gas composition sensor 17 detects the partial pressure of oxygen in the exhaust gases, which corresponds to the stoichiometric composition of the mixture, and, in the event that this correspondence is violated, is determined by

The feedback signal is generated in a closed fuel control system, which in block 18 is generated as a command signal. The latter is supplied to the executive element of the regulator of the stabilizer of the stoichiometric composition of the mixture 19, which directly acts on the body regulating fuel supply in this case on the carburetor 20 with electronic control.

10 Thus, an analysis of the composition of the exhaust gases is carried out and, in case of its deviation from the composition corresponding to the stoichiometric mixture, a command signal is generated for its recovery, which together with the controller

15

signal affect the fuel supply

and the amount of recirculated exhaust gases, with a command signal acting on the fuel supply control authority, and on the control signal - on the control unit 2Q of the amount of recirculated exhaust gases.

In block 25 of the formation of the reference level of instability and its permanent storage device, the family of dependencies D (P) is implemented,

25 obtained at different fixed values of the shaft rotation frequency n and subject to the condition ge.MKH2 at а 1 and 0 Qonr-R- For these dependences for each current value of the load P and the frequency of rotation l, entering the block 25

0 from sensors 22 and 23, respectively, determine the reference level of instability of the Doc (Fig. 2). Thus, the engine load and shaft rotational speed are measured and the reference level of instability is determined.

 Using the sensor 24, the TDC takes measurements of each time interval, i.e. the duration of each engine operating cycle, and the signals from this sensor are used through one. The information on the duration of the working cycles goes both to the block 25 for forming the reference level of instability, and to block 26 for calculating the current instability.

In this block, which also receives data from sensor 23, to calculate the current value of instability, the rotation frequency is fixed at the beginning of each working cycle, the difference of frequencies obtained as a result of

- adjacent measurements, and divide it by the duration of the corresponding working cycle, obtaining acceleration of the shaft rotation in each working cycle, and then calculate the difference between two adjacent accelerations, subtracting from the larger value

5 is smaller, which is the current value of instability. Thus, when calculating the current value of instability, the acceleration of the shaft rotation is determined.

in each working cycle and as the difference of the values determined during two adjacent working cycles, accept the difference of the obtained accelerations.

The calculated current value of instability is fed to one of the inputs of the control signal generation unit 27, the second input of which receives the reference level of instability from block 25.

In block 27, the current value of instability A / is compared with the reference level of the AOP, i.e., the difference between the current value and the reference level of instability is measured, on the basis of which a control signal of a certain shape is generated, for example, a pulse signal of a certain duty ratio. This signal arrives at the control element of the recirculation regulator 28, which is, for example, a recirculation valve solenoid, which is the control element 29. In this case, the number of recir --1

P.p

8-Vdpt.1k ify

.g

) (|

exhaust gases as a percentage of the total amount of exhaust gases Gr% changes so that when a 1 and Q Qom-R, the current value of instability A / tends to the reference level A "i, a the value of specific fuel consumption g tends to geHJUfa. Therefore, the control signal acts to eliminate the difference between the current value and the reference level of instability.

The ignition advance angle 0 is corrected by the signal generated in the correction unit 30, to which, besides the control signal,. Signals are also received from load and rotation speed sensors 22 of the shaft 23. Correction

the advance angle in block 30 is made based on the amount of recycled exhaust gas.

Using the method will reduce exhaust emissions and improve engine efficiency.

MVH6600i

WOO

Claims (1)

METHOD FOR REGULATING THE INTERNAL COMBUSTION ENGINE by measuring each time interval, calculating the value of the instability of the crankshaft rotation as the difference between the values determined in two adjacent intervals, measuring the engine load and the shaft speed, determining the reference level of instability, measuring the difference between the current value and the reference level of instability, generation of a control signal for its elimination for its elimination, analysis of the composition of the exhaust gases and in case of deviation from the composition corresponding to the stoichiometric mixture, generating a command signal for its restoration, which together with the control signal affects the fuel supply and the amount of recirculated exhaust gases, the command signal affecting the fuel supply control element, and the control signal affecting the amount of recirculated exhaust gas control element, characterized in that, in order to improve the regulation process, the duration of the engine operating cycle is taken as a time interval, op the acceleration of rotation of the shaft in each operating cycle is divided and the difference between the accelerations obtained is taken as the difference between the values determined during two adjacent working cycles, and then, taking into account the amount of recirculated exhaust gases, the ignition timing is adjusted. (rig. 1