JP3868016B2 - Fuel metering control method for internal combustion engine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a fuel metering control device for an internal combustion engine in which a first signal representing a basic signal for a fuel amount to be metered is formed depending on an operating parameter of the internal combustion engine.
[0002]
[Prior art]
German Offenlegungsschrift 3,216,983 discloses a control device for a fuel metering device of an internal combustion engine that triggers the enrichment of an air / fuel mixture during acceleration when a predetermined criterion occurs. For example, it is used that the subsequent load value tends to increase, or that the current load value is compared with the arithmetic average value of a plurality of load values before that. If the examination of the criteria reveals that the acceleration air / fuel mixture enrichment should be triggered, a coefficient for correcting the amount of fuel to be metered is formed. This coefficient can depend on operating characteristic quantities such as speed, load, load gradient, temperature, and speed after the start of acceleration.
[0003]
Despite the already very good results with the known control devices, an “acceleration flat spot” occurs in certain internal combustion engines under certain operating conditions, ie The acceleration of the vehicle results in an operating state that disappoints the driver's expectation.
[0004]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to realize the optimum vehicle acceleration characteristics as much as possible. Thus, for example, the enrichment of the air / fuel mixture during acceleration , which is known per se , ie the enrichment of the air / fuel mixture during acceleration, should be improved.
[0005]
[Means and advantages for solving the problems]
The task is to form a signal for fuel metering depending on the operating parameters of the internal combustion engine, for the enrichment of the air / fuel mixture during acceleration that depends on both the engine speed and the time variation of the engine speed. In the fuel metering control method for an internal combustion engine in which the correction signal is superimposed on the signal, the correction signal is obtained using a characteristic map that is a function of the rotational speed and a function of temporal change in the rotational speed, and the rotational speed is determined. However, if the engine speed is outside the pre-settable speed range, or if the time change of the speed does not exceed the pre-set threshold value, the correction signal is set to a value that does not affect the fuel metering. Solved.
[0006]
In the case of the method according to the invention, the fuel metering can be controlled using a correction amount formed from a signal related to the rotational speed and a signal related to the rotational speed change. This eliminates a wide range of acceleration flat spots or depressions that would otherwise occur. This improves the ride comfort. Moreover, the overall performance is improved by the device according to the invention, which in turn allows for faster acceleration.
[0007]
Another advantage according to the invention is that the method according to the invention does not cause any problems with respect to compliance with legally defined exhaust gas limits: the signal tL representing the load of the internal combustion engine exceeds a predetermined threshold tLBA. The fuel metering is controlled by the correction amount only when
[0008]
Further, for the purpose of preventing the steady operation of the internal combustion engine from being affected, the correction amount is changed only when the signal representing the temporal change in the rotational speed exceeds a predetermined threshold. To be formed.
[0009]
Particularly preferably , the correction amount is designed to control the fuel metering only when the signal representing the rotational speed is within a predetermined range. In this case, the predetermined range can be constituted by a plurality of individual regions separated from each other. This suppresses acceleration flat spots very effectively. This is because this preferably takes place at a specific speed.
[0010]
Yet another advantage of the present invention is that a series of different possibilities can be used to form the correction amount, and thus a good cost-performance ratio (cost performance) for each application. Can be achieved. The correction amount can be obtained from, for example, a signal representing the rotational speed and a signal representing a temporal change in the rotational speed by using a characteristic map or by calculation. Furthermore, this correction amount can be obtained from a characteristic curve depending on the signal representing the rotational speed when the signal representing the temporal change in the rotational speed exceeds a predetermined threshold, or the signal representing the rotational speed is It can be determined depending on the signal representing the change in the rotational speed when it is within the predetermined range. Furthermore, when the signal representing the rotational speed change exceeds a predetermined threshold and the signal representing the rotational speed is within a predetermined range, a predetermined value can be assigned to this correction amount.
[0011]
Next, the present invention will be described in detail based on the embodiments shown in the drawings.
[0012]
[Explanation of Examples]
FIG. 1 shows a block circuit diagram of a control device according to the present invention. An air / fuel mixture is supplied to the internal combustion engine 100 via the intake pipe 102, and exhaust gas of the internal combustion engine 100 is discharged to the exhaust pipe 104. In the intake pipe 102, as viewed in the direction of the flow of air sucked in, an air amount measuring device or air mass measuring device 106, a throttle valve 108, and a sensor provided on this for detecting an opening angle α of the throttle valve 108 Furthermore, at least one injection valve 112 is arranged. The internal combustion engine 100 is provided with a rotational speed sensor 114 that detects the internal combustion engine rotational speed n. In order to control the injection valve 112, a signal ti relating to fuel metering is generated by a fuel control device 116 known per se. This signal ti is combined with the correction amount F at the connection point 118, and the signal ti ′ thus formed is guided to the injection valve 112.
[0013]
The correction amount F is formed by the block 120 and led to the coupling point 118 via the switch 122. Block 120 has two inputs. A signal n formed by the rotation speed sensor 114 is supplied to the first input side. To the second input side of the block 120, a signal dn representing a temporal change in the rotational speed n is supplied. Signal dn is formed from signal n by block 124. The switch 122 can be selectively opened or closed by the control stage 126. If the load tL of the internal combustion engine 100 is larger than a predetermined threshold value tLBA, the control stage 126 closes the switch 122. The predetermined threshold value tLBA is stored in the fixed value memory 128 and transferred to the control stage 126 via the connection line. The load tL is determined by the control stage 126, for example, by dividing the signal Q sent from the air mass measuring device or the air amount measuring device 106 by the rotational speed signal n. Both signals are fed to the control stage 126 via corresponding inputs.
[0014]
The fuel control device 116 obtains a signal ti related to fuel metering from a series of operation parameters. The signal ti is formed, for example, by combining a basic signal that depends on the load and the rotational speed with a correction amount that depends on the operating parameters. This procedure is already known to those skilled in the art and is therefore not described in detail. In addition to the signals Q, n and α shown in FIG. 1, other signals may be supplied to the fuel control device 116 as required. For this purpose, a corresponding acquisition and detection device can be provided which generates these signals if necessary. The control device according to the invention influences the signal ti produced by the known fuel control device 116, which is done by combining the signal ti with the correction amount F at the coupling point 118. The main aspect of the present invention is that the correction amount F is formed. The detailed procedure for this is shown in the flowchart of FIG.
[0015]
FIG. 2 shows a flowchart of the process that proceeds in the control method according to the invention. In the first step 200, a signal n representing the number of revolutions and a signal Q representing the amount of air drawn in or the mass of air are captured and detected. The signal n can be formed by the rotation speed sensor 114, for example. The signal Q is generated by the air quantity measuring device or the air mass measuring device 106.
[0016]
In step 201 following step 200, a signal tL representing the load of the internal combustion engine 100 is formed. In the embodiment shown in FIG. 1, the signal tL is determined from the signals Q and n in the control stage 126, and in particular this is determined by division. However, basically, the signal tL can also be obtained from the signal α formed by the throttle valve sensor 110. Furthermore, the switching state of full load switches provided in many internal combustion engines can be expressed by this signal tL. What is important to the present invention is that the signal tL is somehow related to the load of the internal combustion engine 100.
[0017]
Step 201 is followed by step 202, in which a signal dn relating to the temporal change in the rotational speed is determined from the signal n. The signal dn can be formed, for example, by time differentiation of the signal n, or can be obtained by forming a difference between n consecutive signals. For selection of n consecutive signals, for example, a predetermined time interval can be given in advance, or a constant crank angle interval can be given in advance.
[0018]
In step 203 following step 202, the basic signal ti relating to the amount of fuel to be metered is obtained by the control device 116.
[0019]
Step 203 is followed by step 204. In step 204, the correction amount F is determined depending on the signal n regarding the rotational speed and the signal dn regarding the temporal change of the rotational speed. Depending on the embodiment, the correction amount F can be calculated in various ways. One possibility is to read the correction amount F from the characteristic map or characteristic data memory shown on the axes representing n and dn. FIG. 3 shows a characteristic map of this type, which will be described in detail in the relevant section. Yet another possibility is to calculate the correction amount F from n and dn using an appropriate algorithm. Furthermore, when dn exceeds a predetermined threshold, the correction amount F can be read from the characteristic curve depending on n. However, if dn is smaller than the threshold value, a neutral value is assigned to the correction amount F, that is, a value that does not act on the coupling point 118 is associated with the signal transmitted from the fuel control device 116. Another possibility is to read the correction amount F from the characteristic curve depending on the signal dn when the signal n is within a predetermined range. If the signal n is out of range, a neutral value is again assigned to the correction amount F. Furthermore, a threshold for the signal dn and a range for the signal n can be given in advance. If the signal dn exceeds the threshold value assigned to it and the signal n is located within the range assigned to it, a value different from the neutral value is assigned to the correction amount F. In all other cases, a neutral value is assigned to the correction amount F.
[0020]
What is common to all the embodiments is that the correction amount F depends on the signals n and dn. Furthermore, by setting the threshold value or range in advance, or by selecting the characteristic curve or characteristic map accordingly, the correction amount F can be set to medium when the rotational speed is reduced, constant or slightly increased. A sex value will be assigned. In other words, the signal ti sent from the fuel control device 116 is affected by the correction amount F only when the rotational speed n increases significantly. The device according to the invention therefore has no effect during steady operation with respect to the rotational speed n.
[0021]
Step 204 is followed by step 206, in which it is questioned whether the load signal tL determined in step 201 is greater than a threshold value tLBA stored in the fixed value memory 128. If this is the case, step 206 is followed by step 208, in which switch 122 is closed.
[0022]
Step 208 is followed by step 210, in which the signal ti determined in step 203 is corrected by the correction amount F determined in step 204. Step 210 ends the flow of the flowchart.
[0023]
If the question in step 206 is negative, step 212 is followed by step 212. In step 212, the switch 122 is opened, that is, no matter what value the correction amount F has, if it is below the load threshold tLBA, the signal ti sent from the fuel control device 116 is not corrected. In step 212, the flow of the flowchart ends.
[0024]
FIG. 3 shows an example of the characteristic curve area for the correction amount F, which is shown on the axis representing the signal n relating to the rotational speed and the signal dn relating to the change in the rotational speed. The characteristic curve region shown in the figure relates to an embodiment in which the coupling at the coupling point 118 is realized as multiplication, that is, in this case, the neutral value of the correction amount F is the value 1. If the rotational speed change dn is less than 160 / rpm / s, the correction coefficient takes the value 1. The value of the correction coefficient increases as the rotational speed change dn increases. Outside the rotational speed range of 1600 rpm to 2800 rpm shown in FIG. 3, the correction coefficient F takes the value 1 regardless of the rotational speed change dn. Within the illustrated rotational speed range, the correction coefficient F first increases as the rotational speed n increases, and decreases again after reaching the maximum value. It is dependent on the rotational speed change dn how much the gradient after the rise is performed and how large the maximum value is.
[0025]
【The invention's effect】
According to the present invention, the optimum vehicle acceleration characteristic can be realized as much as possible, and the enrichment of the air / fuel mixture during acceleration , that is, the enrichment of the air / fuel mixture during acceleration can be improved.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram of an apparatus for implementing a control method according to the present invention.
FIG. 2 is a flowchart of a process performed by the control method according to the present invention.
FIG. 3 is a diagram showing a characteristic region portion for obtaining a correction amount by the control method according to the present invention.

Claims (3)

A signal for fuel metering that depends on the operating parameters of the internal combustion engine and a correction signal for enrichment of the air / fuel mixture during acceleration that depends on both the engine speed and the time variation of the engine speed ( In the fuel metering control method for an internal combustion engine, wherein F) is superimposed on the signal,
The correction signal (F) is obtained using a characteristic map that is a function of the rotational speed (n) and is also a function of a temporal change (dn) in the rotational speed.
If the rotational speed (n) is outside the presettable rotational speed range, or if the temporal change in the rotational speed does not exceed the presettable threshold, the correction signal (F) is used for fuel metering. It is set to a value that does not affect,
A fuel metering control method for an internal combustion engine. The correction signal (F) is superimposed on the fuel metering signal (ti) only when the signal (tL) indicating the load of the internal combustion engine (100) exceeds a preset threshold (tLBA). To
The control method according to claim 1. The signal representing the load (tL) is formed from the signal (Q) and the rotational speed (n) of the air mass meter or air volume meter (106), or
The signal representing the load (tL) is formed from a signal (α) indicating the opening angle of the throttle valve (108), or
The signal representing the load (tL) is formed from a signal representing the switching state of the full load switch, or
Forming a signal (tL) representing said load from a signal indicative of the pressure in the intake pipe (102);
The method of claim 1.

Images