JPH05340291A - Calculation method for intake air amount information - Google Patents

Abstract

PURPOSE:To dispense with an expensive air flow sensor by calculating a volumetric efficiency of an engine based on an engine speed and a boost pressure of an intake passage, multiplying it by the boost pressure, and thereby obtaining an intake air amount information of an engine. CONSTITUTION:An intake temperature sensor 16 and an atmospheric pressure sensor 17 are arranged inside an air cleaner 15. A boost pressure sensor 24 is arranged inside a serge tank 19. Signals therefrom are input to an ECU 18. The ECU 18 controls a solenoid valve 25 for operating an injection nozzle 26. The ECU 18 calculates a volumetric efficiency of an engine 11 based on signals from the sensors 16, 17 and 24, and controls electric-supply time of the solenoid 25 so as to supply fuel according to the volumetric efficiency. The volumetric efficiency of the engine is calculated by calculating an engine speed and a boost pressure from the signals of a crank angle rotation sensor 36 and the boost pressure sensor 24, and an intake air amount information is obtained by calculating the boost pressure and a temperature correction amount, so that it is not necessary to use an expensive air flow sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calculating intake air amount information of an engine from the rotational speed of the engine and the pressure in an intake passage of the engine.

[0002]

2. Description of the Related Art Generally, the amount of fuel supplied to an engine, its ignition timing, etc. are generally the rotational speed of the engine, the pressure in the intake passage of the engine (hereinafter referred to as boost pressure), or the intake air amount of the engine. The optimum value is set in advance based on the above.

Normally, the engine speed (hereinafter simply referred to as engine speed
Ignition timing based on the rotational speed) and boost pressure
When controlling the operating condition of the engine such as
As shown in FIG. 3 showing the control procedure, the engine speed N
_EEngine speed sensor to detect the
Boost pressure P_BWith boost pressure sensor to detect
In step S1, the detection signals from these sensors
More current engine speed N_EAnd boost pressure P_BDetect and
Then, in step S2, these engine speeds N _EWhen
Boost pressure P_BAs shown in FIG. 4 written based on
Map, the optimum ignition timing (compression top dead center based on
The amount of advance angle is shown as an angle.)
Engine speed N in advance_EAnd boost pressure P_BBased on
For each cylinder volume of the engine as shown in FIG.
Air intake efficiency (hereinafter referred to as volume efficiency) η
_VFrom the map of the current volume efficiency η_VTo step S3
And read this volume efficiency η in step S4._VAnd
Last pressure P_BCalculate the basic fuel supply by multiplying and
is doing.

When the engine operating conditions such as the ignition timing θ and the fuel supply amount are controlled based on the engine speed N _E and the intake air amount, the engine speed sensor for detecting the engine speed N _E is used. And an air flow sensor such as a Karman vortex flowmeter, calculate the intake air amount per one revolution of the engine (hereinafter referred to as intake charge efficiency) ζ from the detection signals from these sensors, and then While the basic fuel supply amount is calculated based on the intake charging efficiency ζ, it is written in advance based on the engine rotation speed N _E and the intake charging efficiency ζ.
The optimum ignition timing (in the figure, the advance amount based on the compression top dead center is represented by an angle) θ is read from the map as shown in FIG.

[0005]

The method of controlling the operating state of the engine based on the engine speed N _E and the boost pressure P _B shown in FIGS. 3 to 5 directly measures the intake air amount of the engine. That is not the case, so the matching technology based on actual engine operation is very important. Therefore, in terms of shortening the development period of a new vehicle and easiness of control, a system that controls the operating state of the engine based on the engine speed N _E and the intake air amount is more advantageous.

However, in the method of controlling the operating state of the engine on the basis of the engine speed N _E and the intake air amount, it is necessary to use an extremely expensive air flow rate sensor, and a part of this air flow rate sensor is used. Since it becomes a resistance against the intake air flowing in the intake passage, the pressure loss becomes a non-negligible amount in a high performance engine.

From the above, a method of controlling the operating state of the engine based on the engine speed N _E and the boost pressure P _B by using a boost pressure sensor capable of significantly reducing the cost as compared with the air flow rate sensor Is getting attention again.

The problem with the method of controlling the operating state of the engine based on the engine speed N _E and the boost pressure P _B is that
As mentioned above, since the intake air amount of the engine is not directly measured, if the specifications of the engine change, the actual engine operation is matched each time and the results are shown in Figs. 4 and 5. It is necessary to recreate the map as shown, which is very troublesome and has the drawback of increasing the development cost of a new car or the like.

Further, a vehicle adopting a method of controlling the operating condition of the engine based on the engine speed N _E and the boost pressure P _B, and the operating condition of the engine based on the engine speed N _E and the intake air amount. 4 and 6 are not compatible even if the specifications of the engines mounted on these vehicles are exactly the same, when the vehicles adopting the control method of the above are mixed in the same production line. It is necessary to develop independent control software having a map as shown, which leads to high cost.

[0010]

An object of the present invention is to provide a method for controlling the operating condition of an engine based on the engine speed and boost pressure, and a method for controlling the operating condition of the engine based on the engine speed and intake air amount. An object of the present invention is to provide a method of calculating intake air amount information, which is used to calculate the intake air amount information from the engine rotation speed and the boost pressure of the engine so that control software can be shared.

[0011]

A method for calculating intake air amount information according to the present invention calculates the volumetric efficiency of the engine based on the engine speed and the boost pressure in the intake passage of the engine, and calculates the volumetric efficiency. Is multiplied by the boost pressure in the intake passage to obtain intake air amount information of the engine.

[0012]

The volumetric efficiency of the engine is calculated on the basis of the engine speed and the pressure in the intake passage of the engine. This calculation work is read in as a map, for example, from experiments for each engine having different specifications.

When the volumetric efficiency of the engine is known from the current engine speed and the pressure in the intake passage of the engine, the volumetric efficiency is multiplied by the boost pressure to obtain information on the intake charge efficiency of the engine. Be done. Then, the operating state of the engine is controlled based on the information on the intake charging efficiency and the engine rotation speed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, which shows the concept of an embodiment in which the method of calculating intake air amount information according to the present invention is applied to the determination of ignition timing and fuel supply amount of an engine, a combustion chamber 1 of an engine 11 is shown.
An air cleaner 15 is connected to the front end of an intake pipe 14 that communicates with the base 2 through an intake valve 13. An intake air temperature sensor 16 and an atmospheric pressure sensor 17 for detecting an intake air temperature T _A and an atmospheric pressure P _A introduced into the air cleaner 15 are assembled in the air cleaner 15, respectively. An electronic control unit (hereinafter, referred to as an ECU) 18 that receives a detection signal output from the sensor 17 is connected to the sensor 17.

In the intake passage 20 formed in the intake pipe 14 on the upstream side of the surge tank 19 provided in the middle of the intake pipe 14, in conjunction with the operation of the accelerator pedal 22 via a cable 21, A throttle valve 23 that adjusts the amount of intake air supplied into the combustion chamber 12 by changing the opening degree of the intake passage 20 is installed. The surge tank 19 has a boost pressure P in the surge tank 19. A boost pressure sensor 24 that detects _B and outputs the detection signal to the ECU 18 is assembled.

On the downstream end side of the intake passage 20, the engine 1
1, a fuel injection nozzle 25 of a fuel injection device for injecting fuel (not shown) into the combustion chamber 12 is provided.
Fuel is injected from the fuel injection nozzle 25 into the combustion chamber 12 via the electromagnetic valve 26 whose duty is controlled by That is, based on the detection signals from the above-mentioned sensors 16, 17, 24 and other sensors described later, based on the volume efficiency η _V of the engine 11 calculated by the ECU 18, fuel corresponding to this is supplied. The fuel injection time t _I described later.
Is controlled to control the energization time of the electromagnetic valve 26, and thereby the inside of the combustion chamber 12 is set to a predetermined air-fuel ratio.

The ignition plug 27 facing the combustion chamber 12 of the engine 11 includes an ignition coil 28 and a power transistor 29.
Is connected to a distributor 30 having a built-in. Then, a high voltage is generated in the ignition coil 28 by the off operation of the power transistor 29, and the spark plug 29 is spark-discharged, while the ignition coil 28 is started to be charged by the on operation of the power transistor 29.

The details of the control of the ignition timing are well known in, for example, Japanese Patent Laid-Open No. 2-241980.

Therefore, in the normal operating state of the engine 11,
The air sucked into the intake passage 20 via the air cleaner 15 in accordance with the opening degree of the throttle valve 23 is mixed with the fuel injected from the fuel injection nozzle 25 so as to have an appropriate air-fuel ratio, and then in the combustion chamber 12. This air-fuel mixture is ignited and burned by the spark plug 27 and becomes exhaust gas, which is the combustion chamber 1 of the engine 11.
2 is exhausted to the outside from an exhaust passage 33 formed in an exhaust pipe 32 which communicates with the base 2 through an exhaust valve 31.

In order to maintain a good operating condition of the engine 11, various sensors are provided in this embodiment, and the ignition timing θ of the ignition plug 27 is determined based on the detection signals from these sensors.
The injection time t _I of the fuel from the fuel injection nozzle 25 and the like are controlled. Specifically, the intake air temperature sensor 16 described above
In addition to the atmospheric pressure sensor 17 and the engine 11,
Water temperature sensor 34 is provided for detecting the cooling water temperature T _W,
Further, the distributor 28 includes a top dead center sensor 35 that detects the compression top dead center position of each cylinder of the engine 11 and detects the compression top dead center position of a preset first cylinder of these four cylinders. , A crank angle sensor 36 for detecting a crank angle phase with reference to the compression top dead center position in the first cylinder is incorporated.
The detection signals from 4 to 36 are output to the ECU 18, respectively.

As shown in FIG. 1 showing the control block of this embodiment by the ECU 18, this embodiment uses the above crank angle sensor 36 as an engine rotation speed sensor for detecting the engine rotation speed N _E. Based on the detection signals from the crank angle sensor 36 and the boost pressure sensor 24, the current engine speed N _E and the boost pressure P _B are calculated in step R1.

Based on the engine speed N _E and the boost pressure P _B , the current volumetric efficiency η _V of the engine 11 is read from the preset map as shown in FIG. The volume efficiency η _V , the boost pressure P _B, and the temperature correction amount (T ₀ / T) ^k are multiplied to calculate the mass-based intake air charging efficiency ζ _M shown in the following equation (1) at the step of R3. The volume-based intake charging efficiency ζ _V shown in the following equation (2) is calculated. ζ _M = η _V · P _B · (T ₀ / T) ^k ··· (1) ζ _V = ζ _M · (P ₀ / P _A ) · (T / T ₀ ) ··· (2)

However, T ₀ is the absolute temperature in the standard state (273 K), T is the current absolute temperature, and k is 0.4.
Is a matching constant of 0.6. Further, P ₀ is the absolute pressure (760 mmHg) in the standard state, and P _A is the current atmospheric pressure (absolute pressure).

Then, in step R4, the current ignition timing θ of the engine is read out from a preset map as shown in FIG. 6 based on the engine speed N _E and the volume-based intake charging efficiency ζ _V , while R5 In the step of, the air-fuel ratio correction coefficient c and the battery voltage, which are preset based on the mass-based intake charging efficiency ζ _M , the cooling water temperature T _W , the intake temperature T _A, the atmospheric pressure P _A, etc., are set. The fuel injection time t _I shown in the following formula (3) is calculated as the energization time for the solenoid valve 26 by multiplying it with the injection correction time t _D. t _I = ζ _V・ c ・ t _D・ ・ ・ (3)

The detailed method of setting the fuel injection time t _{I and} the like are well known in Japanese Patent Application Laid-Open No. 2-241942.

In the case of an engine incorporating an air flow rate sensor, the intake air amount calculated based on the detection signal from the air flow rate sensor is divided by the engine rotational speed N _E , and the volume-based intake charging is performed. While calculating the efficiency ζ _V , the mass-based intake charging efficiency ζ _M shown in the following equation (4) is calculated. _{ζ M = ζ V · (P} A / P 0) · (T 0 / T) ··· (4)

Thereafter, as in the previous method, in the step of R4, the engine rotation speed N _E and the volume-based intake charging efficiency ζ _V
Based on the above, while the current ignition timing θ of the engine is read from the preset map as shown in FIG. 6, the intake air charging efficiency ζ _M on the mass basis, the current air-fuel ratio correction coefficient c, and the injection correction time are read in the step of R5. The fuel injection time t _I shown in the equation (3) is calculated by multiplying by t _D.

That is, the read operation of the ignition timing θ in the step R4 and the fuel injection time t _{I in} the step R5 are performed.
Setting the work in, it is possible to share the both control software when using a case and an air flow rate sensor using a boost pressure sensor 24, the engine rotational speed N _E and the boost pressure P _B
A vehicle that employs a method of controlling the operating state of the engine 11 based on the above and a vehicle that employs a method of controlling the operating state of the engine 11 based on the engine speed _NE and the intake air amount In the case of mixed lines, if the specifications of the engines 11 mounted on these vehicles are exactly the same, the development cost of the control software can be reduced.

When the specifications of the engine 11 change,
It suffices to create a map of the current volumetric efficiency η _V of the engine as shown in FIG. 5 corresponding to the engine speed N _E and the boost pressure P _B each time, and it is not necessary to change the control software thereafter. , It is possible to shorten the development period of a new car.

[0030]

According to the intake air amount information calculation method of the present invention, the volumetric efficiency of the engine is calculated based on the engine speed and the boost pressure of the engine, and the volumetric efficiency is boosted in the intake passage. Since the intake air amount information of the engine is obtained by multiplying the pressure, it becomes possible to control the operating state of the engine based on the intake air amount without using an expensive air flow sensor. Even if the specification of is changed, it is only necessary to correct the volumetric efficiency of the engine, and it is not necessary to reset the ignition timing etc. by the matching operation.

Further, since the operating condition of the engine can be controlled based on the intake air amount information of the engine, a part of the control software of the system for controlling the operating condition of the engine using the conventional air flow rate sensor is unchanged. A vehicle that can be used and adopts a method of controlling the operating state of the engine based on the engine speed and boost pressure, and controls the operating state of the engine based on the engine speed and intake air amount Even if vehicles that use the method are mixed on the same production line, most of the controls can be made compatible, so there is no need to develop independent control software, which reduces costs. Became possible.

[Brief description of drawings]

FIG. 1 is a flowchart showing a control procedure of an embodiment in which a method of calculating intake air amount information according to the present invention is applied to determination of an ignition timing of an engine and a fuel supply amount.

FIG. 2 is a conceptual diagram showing a control system of an engine which is a target of the present embodiment.

FIG. 3 is a flowchart of a conventional control procedure for determining an engine ignition timing and a fuel supply amount based on an engine rotation speed and a boost pressure.

FIG. 4 is a map of ignition timing corresponding to engine speed and boost pressure.

FIG. 5 is a map of the volumetric efficiency of the engine as a function of engine speed and boost pressure.

FIG. 6 is a map of ignition timing corresponding to engine speed and intake charge efficiency on a volume basis.

[Explanation of symbols]

 11 is an engine, 12 is a combustion chamber, 13 is an intake valve, 14 is intake air
Pipe, 15 air cleaner, 16 intake air temperature sensor, 17
Atmospheric pressure sensor, 18 is ECU, 19 is surge tank, 2
0 is an intake passage, 21 is a cable, 22 is an accelerator pedal
23, throttle valve, 24 boost pressure sensor, 2
5 is a fuel injection nozzle, 26 is a solenoid valve, and 27 is an ignition plug.
28, ignition coil, 29 power transistor, 3
0 is a distributor, 31 is an exhaust valve, 32 is exhaust
Pipe, 33 exhaust passage, 34 water temperature sensor, 35 top dead center
Sensor, 36 is a crank angle sensor, and c is an air-fuel ratio supplement
Positive coefficient, θ is the ignition timing of the engine, k is a constant, η_VIs the institution
Volume efficiency, N_EIs the engine speed, ζ _MIs mass-based intake
Filling efficiency, P_AIs atmospheric pressure, ζ_VIs the volume-based intake filling effect
Rate, P_BIs boost pressure, P₀Is the absolute pressure under standard conditions,
T is the current absolute temperature, T₀Is the absolute temperature at standard conditions
Degree, t_DIs the injection correction time, t_IIs the fuel injection time.

Claims (1)

[Claims] 1. The intake efficiency of air per cylinder volume of the engine is calculated based on the engine speed and the pressure in the intake passage of the engine, and the intake efficiency is multiplied by the pressure in the intake passage. The intake air amount information of the engine is obtained by doing so.