JPH01155041A - Cylinder inflow gas quantity compensating method - Google Patents

Abstract

PURPOSE:To make a gas flow rate flowing into a cylinder calculable in real time by compensating the detected value of a flow measuring device an and around a throttle valve with throttle valve opening and rotational frequency. CONSTITUTION:A flow measuring device 3, measuring a quantity of flow Qt passing through a throttle valve 2, is installed in and around this throttle valve 2. A detected value Qt of the flow measuring device 3 is inputted into a correction factor generator 8 together with each detected value thetat of a throttle valve opening sensor 6 and a crank angle sensor 7 and N, and an inflow quantity Qz into a cylinder 5 is operated by a correction factor set out of a table on the basis of throttle valve opening and rotational frequency. A fuel flow rate decider 9 operates an injection quantity out of a fuel injector 10 on the basis of the inflow quantity Qz into the cylinder 5.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a passenger car engine, and particularly relates to a method for correcting the amount of gas flowing into the cylinder, which is suitable for correctly grasping the amount of gas flowing into the cylinder of the engine. .

[Conventional technology]

Generally, the amount of gas passing through an intake valve of a passenger car engine is expressed as a function of pressures before and after the valve, temperature, valve opening area, etc. However, these are simultaneous differential equations, and it is difficult to integrate them in real time using an approximately 8-bit microprocessor and use them for engine control. For this reason, methods are used such as measuring the flow rate using a flow meter (air flow meter) near the Scott 1 to 2 valves in the intake pipe and approximating this as the amount of gas flowing into the engine cylinder. .

Literature “Automotive Technology VoQ, 39.N [19(7)1-0
FIG. 4J on page 03 shows an example of a fuel injection control system that uses such a method to determine the amount of fuel supplied to the engine. In this conventional example, the amount of air measured by an air flow meter is transmitted to the engine controller 1 to the roll computer, and the amount of fuel is adjusted so that the ratio of this amount of air to the amount of fuel to be supplied becomes, for example, 14.7, which is called the stoichiometric air-fuel ratio. Spray as scheduled. Here, since the operating conditions of the engine change dynamically, it is often difficult to keep this ratio constant, so the amount of oxygen in the exhaust gas is checked with the 02 sensor installed in the exhaust pipe in the figure, and the injection Measures are taken such as determining how much fuel is available and applying a fee back to the next fuel amount calculation.

In such a method, it is preferable that the amount of air at the position where the fuel is injected is accurately determined.

If the injection position and the air flow meter position are far apart as in the above literature, the difference in air flow rate at the surface position will become large depending on the opening degree of the throttle valve, and the actual air-fuel ratio will deviate from the desired value. have a tendency.

[Before the problem that the invention seeks to solve]

The above conventional technology does not take into consideration the difference between the air flow rate at the measurement position and the air flow rate at the fuel injection position or intake valve position, and does not allow calculation of the amount of injected fuel or the amount of mixed gas flowing into the cylinder. This caused a discrepancy in the calculation of the actual value, and there was a problem in that the engine output could not be adequately controlled.

The purpose of the present invention is to perform corrections that take into account the effects of throttle valve opening and engine speed, which are considered to have a particularly large effect on the gas flow rate depending on the flow rate measurement position, and to calculate the actual amount of gas flowing into the engine cylinder. The purpose is to estimate.

Means for Solving Problem C] The above purpose is to measure the flow rate by combining a flow rate measuring device installed near the throttle valve of the intake pipe, a throttle valve sensor, a crank angle sensor, and a correction coefficient generator. This is achieved by correction.

[Effect]

The flow rate measuring device is installed near the throttle valve.

Measure the gas flow rate passing through the throttle valve (and including the bypass if there is one nearby). The throttle valve sensor detects the throttle valve opening, and the crank angle sensor detects the engine rotation speed.

According to experiments or numerical simulations of engine models, the gas flow rate passing through the Scots 1-1 valve does not necessarily correspond to the gas flow rate passing through the intake valve. This difference is particularly large when the throttle valve opening is small.

The correction coefficient generator generates a correction coefficient to be converted into the flow rate passing through the intake valve by multiplying the flow rate measured by the flow rate measurement device obtained through experiments or the like. This has several built-in functions that determine correction coefficients using the throttle valve opening and rotational speed as parameters, and these functions are determined through experiments for each type of engine.

In other words, by inputting the flow rate measured by the flow rate measuring device and the number of rotations of the valve opening 1 to 2 into the correction coefficient generator, a correction coefficient is generated, and the flow rate of the flow rate measuring device is multiplied by the correction coefficient to cause the flow rate to pass through the intake valve. Convert to the flow rate.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. In the vicinity of the throttle valve 2 in the intake pipe 1, the flow rate Qt passing through the throttle valve 2 is measured using a known flow rate measuring device 3 such as that described in the above-mentioned literature. The gas that has passed through this passes through the intake valve 4 and flows into the cylinder 5 of the engine. The inflow amounts Q7 and 01 are generally not equal. However, Q7 is determined by the temperature and pressure inside the cylinder 5 and the intake pipe 1, the intake valve opening area, etc., and is difficult to directly measure during engine operation.

In the present invention, the opening angle O1 of the throttle valve 2 is determined by the valve opening sensor 6 provided on the throttle valve 2, and the engine rotation speed N is determined by the crank angle sensor 7. This opening angle is 0. and the engine speed N are input to the correction coefficient generator 8 together with the flow rate Qt measured by the flow rate measuring device 3. The correction coefficient generator 8 determines a correction coefficient from the opening angle 0 and the engine rotation speed N using a built-in function. The flow rate Q1 is corrected using this correction coefficient and outputted as the inflow amount Q2 into the cylinder 5.

This inflow amount Q2 is, for example, 3 on page 1.003 in the above-mentioned document.
．． .

This fuel burns in the cylinder 5 and exhaust valve 1 during the exhaust stroke.
]- into the exhaust pipe 12.

Figure 2 shows an example of basic data for determining the function built into the correction coefficient generator 8, and shows an example of the opening angle of the throttle valve (J
FIG. 3 is a diagram showing the change in the inflow ratio Qt/Qz due to t under a constant rotation speed N. FIG. The test engine had a compression ratio of 8.5,
Cylinder inner diameter 9/l, 5 mm, stroke 96
．． 4 mm, but this data varies depending on the shape of the intake pipe and intake valve even for the same engine. According to the data in Fig. 2, when the opening angle Ot is larger than 60 degrees, the inflow ratio Q t /Q 2 is approximately ], but at 10 degrees, this ratio becomes smaller and the flow rate Q2 becomes larger. It becomes more than Qt. This tendency becomes more pronounced as the engine speed N increases.

The correction coefficient generation 8 is performed by approximating the data curve shown in FIG. 2 by dividing it by the opening angle Ot of the throttle valve for each engine speed N and using a polygonal line or curve, and based on the approximation formula, calculates the engine speed obtained from the sensor. The inflow ratio Qt/Qz is determined from the number N and the opening angle O1 of the throttle valve, and it is applied to the flow rate Q determined from the flow rate measuring device 3 to obtain the flow rate Q7.

Figure 3 shows how to express this approximation formula, for scope of application Upper limit of engine speed Nu Lower limit of engine rotation speed N.

Scot 1 - Lower limit of the opening angle of the throttle valve Ot.

Equation type code E for calculation approximation formula for flow rate ratio Q, /Q (1: linear equation, 2: quadratic equation, etc.) Coefficient group CJ according to the type of equation (j = 1 to m)
(-formula: m, = 3) A set of values (Nu+ ND+ Otυ, (lto, E, C1
, C2, Cs...).

In terms of programming technique, this data group consists of two types of tables formed from the following value sets, as shown in FIG.

Table 1 is arranged such that (N()+NgrT) is in ascending order with respect to engine speed. T is a table name indicating a selection among the second plurality of tables.

The table 2 is arranged such that (Otn+01υ, E, C, C2, . . . ) are arranged in ascending order with respect to the opening angle of the Scott 1 valve. However, it consists of multiple tables of similar format, each given a table name.

FIG. 5 shows that the correction coefficient generator 8 calculates the engine rotational speed N and the opening angle θ of the throttle valve from the sensor.

The procedure for determining the flow rate Q2 from the flow rate Qt from the flow rate measuring device 3 and the table data shown in FIG. 4 will be described. That is, (1) Search table 1 and find a table name T that satisfies ND≦N<N u .

(2) Search for a data group that satisfies OtD≦(l t < Otu among the table craftsmen determined by (1) from Table 2, and find the type code that indicates the equation of a straight line and the following coefficient group. Suppose that it was established from

(CI T 62 + Cs) (3) Calculate the inflow ratio as follows.

Qt C engineering C8
Q z C2C2 (4) According to this embodiment, the flow rate Q2 into the cylinder is determined by using the inflow ratio, and the following effects are obtained.

As shown in FIG. 1, it is assumed that the fuel injector 10 is located on the engine side away from the flow meter. At this time, the air-fuel ratio is set to 1
4.7, the flow rate should be Q, not Qt.

If fuel B is determined to be 14.7 according to Qt, then from Figure 2, when the opening angle of the Scots 1 to 1 valve is 10 degrees and the engine speed is 800 per minute, QZ will be as follows.
The air-fuel ratio is 22.6, which causes unstable combustion due to the lean mixture.

Q.

□20, 65 -= 1 4. , 7 B That is, -=22.6 Therefore, by providing the correction coefficient generator 8 of the present invention, such unstable combustion can be avoided.

〔Effect of the invention〕

According to the present invention, the gas flow rate flowing into the cylinders of the engine can be determined from the gas flow rate measured by the flow rate measuring device near the throttle valve of the intake pipe without solving a differential equation or the like.
Since it can be determined in real time, parameters necessary for engine control, such as determining the amount of fuel injected into the cylinder and estimating engine output, can be determined to match actual values.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an engine system showing an embodiment of the present invention;
Figure 2 is a correlation curve between the ratio of the flow rate passing through the throttle valve to the flow rate flowing into the engine cylinder and the opening angle of the throttle valve, and Figure 3 is an approximation expressed for the correction coefficient generator based on Figure 2. FIG. 4 is a table replacement diagram showing the relationship in FIG. 3, and FIG. 5 is a processing flow diagram showing the procedure within the correction coefficient generator. DESCRIPTION OF SYMBOLS 1...Intake pipe, 2...Scot 1~le valve, 3...Flow rate 2111 + constant device, 4...Intake valve, 5...In cylinder, 6...Scot 1 Hell valve opening sensor , 7. Crank angle sensor, 8.. Correction coefficient generator, 9.. Fuel quantity determiner, 10.. Fuel 5. ″・Page calculation T ○−= Qf, /4,1

Claims (1)

[Claims] 1. A throttle opening sensor and a crank angle sensor are installed in an engine equipped with a flow rate measurement device near the throttle valve, and the flow rate measured by the flow rate measurement device is corrected based on the throttle valve opening degree and rotational speed before entering the engine cylinder. A method for correcting the amount of gas flowing into a cylinder, characterized in that the flow rate is set to a flow rate of .