JPH07269402A - Atmospheric pressure correction device for engine - Google Patents

Abstract

PURPOSE:To realize highly accurate injection control in consideration of atmospheric pressure and intake pressure without requiring a process of computing an atmospheric pressure correction factor, by correcting an intake air quantity based on volumetric efficiency obtained from an engine speed and a ratio of intake air pressure to atmospheric pressure to compute a fuel injection quantity. CONSTITUTION:In a control device 104 wherein output signals of a crank angle sensor 88, intake air pressure sensor 92 and atmospheric pressure sensor 94 are inputted during engine operation, first an intake air quantity is obtained from an engine speed Ne and intake air pressure Pb, and a fuel injection quantity is computed to obtain a target air-fuel ratio so as to operation-control a fuel injection valve 52. In this case, an atmospheric pressure control part 120 in an atmospheric pressure correction device 118 controls so that volumetric efficiency CEV may be obtained from the engine speed Ne and a ratio Pb/Pa of the intake air pressure Pb to atmospheric pressure Pa by means of map interpolation, an intake air quantity may be corrected with this volumetric efficiency CEV, and a fuel injection quantity may be computed based on the intake air quantity after correction. With this constitution, highly accurate injection control is realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine atmospheric pressure compensating device, and in particular, it is possible to appropriately correct the intake air amount by the atmospheric pressure at all loads, calculate an appropriate fuel injection amount, and exhaust gas. The purification performance can be improved, the atmospheric pressure correction coefficient calculation process for correcting the intake air amount when calculating the fuel injection amount can be unnecessary, the fuel injection control can be simplified, and the control memory can be saved. The present invention relates to an atmospheric pressure correction device for an engine.

[0002]

2. Description of the Related Art Some engines mounted on vehicles are equipped with a fuel injection control device for controlling the amount of fuel injected by a fuel injection valve as a measure against the harmful exhaust gas components and fuel consumption. Some fuel injection control devices calculate the fuel injection amount by obtaining the intake amount from the intake pressure, which is the intake pipe pressure, and the engine speed.

In such a fuel injection control device,
Since the filling efficiency in the combustion chamber changes depending on the atmospheric pressure, it is necessary to calculate the fuel injection amount by correcting the intake air amount by the atmospheric pressure.

The correction of the intake air amount by the atmospheric pressure is as follows.
As shown in FIG. 6, the atmospheric pressure correction coefficient CAP is stored in the memory of the control unit as table data of the atmospheric pressure Pa, and the atmospheric pressure correction coefficient CAP is stored from the table data of the atmospheric pressure Pa.
There is a method in which the intake air amount is corrected by obtaining the value by table interpolation.

In order to correct the intake air amount by the atmospheric pressure, the volumetric efficiency CEV calculated by map interpolation from the engine speed Ne and the intake pressure (boost pressure) Pb is used as shown in FIGS. There is one that corrects the intake air amount by correcting with an atmospheric pressure correction coefficient CAP obtained from a table of atmospheric pressure Pa.

[0006]

By the way, in the engine, when the atmospheric pressure becomes low, the air-fuel ratio becomes lean unless it is corrected by the atmospheric pressure. At this time, even if the air-fuel ratio is the same atmospheric pressure, the leaner the tendency, the greater the load.

Therefore, when the intake air amount is corrected by using the atmospheric pressure correction coefficient CAP determined only by the atmospheric pressure Pa, the correction amount becomes small and insufficient at low load, while the correction amount becomes insufficient at low load. There is a problem that the correction amount becomes large and becomes excessive.

Therefore, when the intake air amount is corrected using the atmospheric pressure correction coefficient CAP determined only by the atmospheric pressure Pa, the intake air amount cannot be properly corrected by the atmospheric pressure at all loads. As a result, an appropriate fuel injection amount cannot be calculated, the air-fuel ratio becomes inadequate, and there is a disadvantage that exhaust purification performance is deteriorated.

Therefore, the intake air amount can be properly corrected by obtaining a correction coefficient from a map based on the load and the atmospheric pressure, and not by using only the atmospheric pressure.

However, the process of obtaining the correction coefficient from the map based on the load and the atmospheric pressure has a disadvantage that the fuel injection control becomes complicated and a large amount of control memory is required.

Further, the volumetric efficiency CEV obtained by map interpolation from the engine speed Ne and the intake pressure (boost pressure) Pb shown in FIGS. 7 and 8 is given by the atmospheric pressure correction coefficient CAP obtained from the table of atmospheric pressure Pa. There is a correction for correcting the intake air amount, for example, atmospheric pressure Pa = 350
〓 To find the volumetric efficiency CEV at Hg, use CEV
(Pa = 350〓Hg) = CEV (Pa = 760〓Hg)
× CAP.

Therefore, the volumetric efficiency CEV is determined by the intake pressure Pb.
Even if changes, the atmospheric pressure correction coefficient CAP is constant, so
The value is as shown by the broken line in FIG.

As a result, at a high load, the intake air amount is corrected by the atmospheric pressure correction so that the intake amount is larger than it actually is, so that the calculated fuel injection amount becomes larger than the required fuel injection amount. There is a disadvantage that the air-fuel ratio becomes rich.

On the other hand, at low load, the intake air amount is corrected by atmospheric pressure correction so that the intake amount is smaller than the actual intake amount, and the calculated fuel injection amount becomes smaller than the required fuel injection amount. There is a disadvantage that the air-fuel ratio becomes lean.

Therefore, in this correction, since the intake air amount due to the atmospheric pressure cannot be properly corrected at all loads, an appropriate fuel injection amount cannot be calculated, the air-fuel ratio becomes unsuitable, and exhaust gas purification is performed. There is an inconvenience that deteriorates performance.

[0016]

SUMMARY OF THE INVENTION Therefore, in order to eliminate the above-mentioned inconvenience, the present invention relates to an atmospheric pressure compensating device for an engine in which fuel is injected and supplied by a fuel injection control device, in which the engine speed of the engine is adjusted. A rotation speed sensor for detecting, an intake pressure sensor for detecting intake pressure of the engine, an atmospheric pressure sensor for detecting atmospheric pressure are provided, and the engine speed detected by the rotation speed sensor and the intake pressure sensor A control means is provided for controlling the intake air amount by the volume efficiency obtained from the ratio of the intake pressure and the atmospheric pressure detected by the atmospheric pressure sensor to calculate the fuel injection amount by the fuel injection control device. .

[0017]

According to the structure of the present invention, the atmospheric pressure correction device is
The control means controls the intake air amount to be corrected by the volume efficiency obtained from the engine speed and the ratio of the intake pressure and the atmospheric pressure to control the fuel injection amount to be calculated, thereby requiring a process of calculating the atmospheric pressure correction coefficient. The volume efficiency can be calculated without considering the intake pressure as well as the atmospheric pressure.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an embodiment of the present invention. 5, 2 is an engine, 4 is a piston, 6 is a combustion chamber, 8 is an intake valve, 10 is an exhaust valve, 12 is an air cleaner, 14 is an intake pipe, 16 is a throttle body, 18 is a throttle valve, and 20 is a surge tank. , 22 is an intake manifold, 24 is an intake passage, 26 is an exhaust manifold, 28
Is a catalytic converter, 30 is an exhaust pipe, 32 is an exhaust passage, 3
Reference numeral 4 is a first blow-by gas pipe, 36 is a second blow-by gas pipe, and 38 is a PCV valve.

The engine 2 includes an exhaust manifold 26.
EGR passage 4 whose one end side communicates with the EGR intake port 40 provided in the exhaust passage 32 and whose other end communicates with the EGR return port 42 provided in the intake passage 24 of the intake manifold 22.
4 is provided. An EGR control valve 46 is provided in the middle of the EGR passage 44.

The EGR control valve 46 is operated by the EGR operation valve 48 via the EGR control pressure passage 50 with the pressure in the intake passage 24 of the surge tank 20 as a control pressure, and controls the opening / closing of the EGR passage 44 to partially discharge the exhaust gas. To EGR
The air is recirculated from the recirculation port 42 to the intake passage 24.

In the engine 2, the intake manifold 22 is provided with a fuel injection valve 52 directed toward the combustion chamber 6. The fuel injection valve 52 is connected to the fuel tank 5 via the fuel supply passage 54.
6 has been contacted. In the fuel tank 56, a fuel pump 58 that supplies fuel to the fuel supply passage 54 is provided. A fuel filter 60 is provided in the middle of the fuel supply passage 54.

A fuel pressure adjusting mechanism 62 is provided in the middle of the fuel supply passage 54. Fuel pressure adjusting mechanism 62
Is operated as an adjustment pressure by the adjustment pressure passage 64 in the intake passage 24 of the surge tank 20, adjusts the fuel pressure to a predetermined pressure, and returns excess fuel to the fuel tank 56 through the fuel return passage 68.

A purge passage 70 is provided in the fuel tank 56.
Communicate with one end side of. The other end of the purge passage 70 is
It communicates with the canister 72. A two-way valve 74 is provided in the middle of the purge passage 70. One end side of the evaporation passage 176 is communicated with the canister 72. The other end of the evaporation passage 76 is connected to the throttle body 16
Of the intake passage 24.

The engine 2 has a throttle valve 18
By providing an idle air passage 78 that connects the intake passage 24 of the throttle body 16 and the intake passage 24 of the surge tank 20 by bypassing the bypass body 16, and an idle air adjusting valve (ISC valve) 80 is provided in the middle of the idle air passage 78. There is.

The engine 2 includes an ignition coil 84 and a distributor 86 which constitute an ignition mechanism 82.
And are provided. The distributor 86 is provided with a crank angle sensor 88 that detects not only the crank angle but also the engine speed and functions as a speed sensor.

The engine is provided with an intake pressure sensor 92 for detecting the intake pressure introduced from the intake passage 24 of the surge tank 20 through the detection pressure passage 90.

The engine 2 is provided with an atmospheric pressure sensor 94 for detecting the atmospheric pressure.

Further, the engine is provided with a water temperature sensor 96 for detecting the cooling water temperature, a throttle sensor 98 for detecting the throttle opening of the throttle valve 18, and an intake temperature sensor for detecting the intake temperature of the intake passage 24. 1
00, and an O2 sensor 102 for detecting the oxygen concentration in the exhaust gas of the exhaust passage 26.

The EGR operation valve 48 and the fuel injection valve 5
2, fuel pump 58, idle air adjusting valve 80, ignition coil 84, crank angle sensor 88, intake pressure sensor 92, atmospheric pressure sensor 94, water temperature sensor 96, throttle sensor 98, intake air temperature sensor 100, O2 sensor 1
02 is connected to the control means 106 that constitutes the fuel injection control device 104.

A thermofuse 108 attached to the catalytic converter 28 is connected to the control means 106 via a warning lamp 110, and the main switch 1
A battery 116 is connected via 12 and a fuse 114.

The control means 106 controls the sensors 88.
The operating state of the engine 2 is detected by a signal input from 92 to 102, the intake amount is obtained from, for example, the intake pressure and the engine speed, and the fuel injection amount is calculated so as to obtain the target air-fuel ratio. The fuel is injected and supplied to the combustion chamber 6 of the engine 2 by controlling the operation of 52.

As described above, the engine 2 supplied with the fuel by the fuel injection control device 104 is provided with the atmospheric pressure correction device 118. An atmospheric pressure control unit 120, which is a control unit of the atmospheric pressure correction device 118, is provided in the control unit 106 of the fuel injection control device 104. The atmospheric pressure control unit 120 controls the engine rotational speed Ne detected by the crank angle sensor 88, which also functions as a rotational speed sensor, and the intake pressure (boost pressure) Pb and atmospheric pressure Pa detected by the intake pressure sensor 92 and the atmospheric pressure sensor 94. The volumetric efficiency CEV is obtained from the ratio Pb / Pa, and the volumetric efficiency CEV is used to correct the intake air amount so that the fuel injection control device 104 calculates the fuel injection amount.

Next, the operation will be described.

As shown in FIG. 1, when the control starts, the atmospheric pressure control section 120 includes a crank angle sensor 88, an intake pressure sensor 92, and an atmospheric pressure sensor 94, which also function as rotational speed sensors, respectively. Ne and intake pressure P
b and the atmospheric pressure Pa are input (step 202).

Input engine speed Ne and intake pressure P
As for b and the atmospheric pressure Pa, as shown in FIG. 2, the volume efficiency CEV is obtained by map interpolation from the engine speed Ne and the ratio Pb / Pa of the intake pressure Pb and the atmospheric pressure Pa (step 20).
4).

The intake air amount is corrected by the obtained volume efficiency CEV (step 206), and the fuel injection control device 104 is operated.
The fuel injection amount is calculated (step 208).

As described above, in the atmospheric pressure correction device 118, the volumetric efficiency C obtained by the atmospheric pressure control unit 120 from the engine speed Ne and the ratio of the intake pressure Pb and the atmospheric pressure Pa.
The EV is controlled to correct the intake air amount and calculate the fuel injection amount.

As a result, the atmospheric pressure correction device 118 can obtain the volumetric efficiency CEV in consideration of the intake pressure Pb as well as the atmospheric pressure Pa without the process of calculating the atmospheric pressure correction coefficient CAP as in the conventional case.

Here, the volumetric efficiency CEV will be described.
The intake air weight Ga of the engine 2 is G as shown in FIG.
a = {Y / (Y + 1)} × {(P ₁ · V _S ) / @ R ₁ ·
(Ta−ΔT ₁ + ΔT _2,4,5 ) @} × {ε / (ε−
1)} × {1- (1 / ε)  (P ₅ / P ₁ ) ^{1 / n} }.

To simplify the explanation, P ₁ = Pb, P
₅ = Pa. Actually, due to various factors, P ₁
= Pb and P ₅ = Pa are not satisfied, but they agree with the trend of volumetric efficiency CEV.

From the above approximate expression, the volumetric efficiency CEV is CEV
= {Y / (Y + 1)} × {1 / @ R ₁ · (Ta−ΔT ₁
+ ΔT _2,4,5 ) @} × {ε / (ε-1)} × {1- (1
/ Ε) · (Pa / Pb) ^{1 / n} }.

Therefore, the volumetric efficiency CEV is CEV = {Y /
(Y + 1)} × {1 / @ R ₁ · (Ta−ΔT ₁ + ΔT
_2,4,5 ) @} x {ε / (ε-1)} x {1- (1 / ε)
・ (Pb / Pa) ^{−1 / n} } (n≈1.3).

Therefore, the volumetric efficiency CEV is Pb / Pa
It turns out that it becomes a function of.

From this, the volume efficiency CEV is the same as the atmospheric pressure P
If a, it may be a function of the intake pressure Pb, but the atmospheric pressure P
When a changes, the conventional atmospheric pressure correction method in which all the intake pressures Pb are multiplied by the same atmospheric pressure correction coefficient CAP cannot be corrected properly.

According to the formula of the volumetric efficiency CEV, it is expressed as shown in FIG. Taking this as the intake pressure Pb on the horizontal axis,
When the atmospheric pressure Pa is expressed as a parameter, it is expressed as shown in FIG.

As is apparent from FIG. 4, when the atmospheric pressure becomes small, the volume efficiency C becomes smaller as the intake pressure Pb becomes smaller.
The rate of increase in EV is large. Therefore, the inconvenience described in the section of the problem to be solved by the invention occurs.

Therefore, in this atmospheric pressure correction device 118, the engine speed Ne, the intake pressure Pb, and the atmospheric pressure Pa are controlled by the atmospheric pressure control unit 120 instead of the conventional intake pressure (Pb).
The volume efficiency CEV is calculated from the ratio Pb / Pa of the fuel injection control device 104 and the intake air amount is corrected by the volume efficiency CEV.
By controlling so as to calculate the fuel injection amount by, the volume efficiency CEV considering the intake pressure Pb together with the atmospheric pressure Pa can be obtained without the process of calculating the atmospheric pressure correction coefficient CAP.

Therefore, the atmospheric pressure correction device 118 is
Instead of the conventional intake pressure (Pb), it is possible to appropriately correct the intake air amount by the atmospheric pressure Pa at all loads, and it is possible to calculate an appropriate fuel injection amount, optimize the air-fuel ratio, and purify the exhaust gas. Can be improved. Further, the atmospheric pressure correction device 118 does not require calculation of the atmospheric pressure correction coefficient C _AP for correcting the intake air amount when calculating the fuel injection amount obtained is unnecessary, the process of calculating the atmospheric pressure correction coefficient CAP As a result, the fuel injection control can be simplified and the control memory can be saved.

[0049]

As described above, according to the present invention, the atmospheric pressure correction device can obtain the volumetric efficiency in consideration of the intake pressure as well as the atmospheric pressure without requiring the process of calculating the atmospheric pressure correction coefficient.

Therefore, the atmospheric pressure correction device can appropriately correct the intake air amount by the atmospheric pressure in all the loads, can calculate the appropriate fuel injection amount, and can optimize the air-fuel ratio to purify the exhaust gas. The performance can be improved, the calculation process of the atmospheric pressure correction coefficient for correcting the intake air amount when calculating the fuel injection amount can be unnecessary, the fuel injection control can be simplified, and the control memory can be saved. You can do it.

[Brief description of drawings]

FIG. 1 is a flowchart of control of an atmospheric pressure correction device.

FIG. 2 is an engine speed Ne, an intake pressure Pb, and an atmospheric pressure P.
It is a figure which shows the volume efficiency CEV map by the ratio Pb / Pa of a.

FIG. 3 is a diagram showing the relationship between the ratio Pb / Pa of the intake pressure Pb and the atmospheric pressure Pa and the volumetric efficiency CEV.

FIG. 4 is a diagram showing the relationship between the intake pressure Pb and the volumetric efficiency CEV with the atmospheric pressure Pa as a parameter.

FIG. 5 is a schematic configuration diagram of an atmospheric pressure correction device.

FIG. 6 is a diagram showing an atmospheric pressure correction coefficient CAP table based on atmospheric pressure Pa showing a conventional example.

FIG. 7 is a diagram showing a volumetric efficiency CEV map based on engine speed Ne and intake pressure Pb.

FIG. 8 is a diagram showing the relationship between the intake pressure Pb and the volumetric efficiency CEV with the atmospheric pressure Pa as a parameter.

[Explanation of symbols]

 2 engine 52 fuel injection valve 88 crank angle sensor 92 intake pressure sensor 94 atmospheric pressure sensor 104 fuel injection control device 106 control means 118 atmospheric pressure correction device 120 atmospheric pressure correction unit

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[Procedure amendment]

[Submission date] May 23, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 6]

[Figure 4]

[Figure 5]

[Figure 7]

[Figure 8]

Claims (1)

[Claims] 1. An atmospheric pressure correction device for an engine, in which fuel is injected and supplied by a fuel injection control device, comprising an engine speed sensor for detecting an engine speed of the engine, and an intake pressure sensor for detecting an intake pressure of the engine. By providing an atmospheric pressure sensor for detecting atmospheric pressure, the volume efficiency obtained from the engine speed detected by the rotation speed sensor and the ratio of the intake pressure and the atmospheric pressure detected by the intake pressure sensor and the atmospheric pressure sensor An atmospheric pressure compensating device for an engine, comprising: a control means for compensating an intake air amount and controlling the fuel injection control device to calculate a fuel injection amount.