JPH06280639A - Control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a control device for an internal combustion engine which can safely detect a concentration of fuel vapor gas at a low cost during purging so as to control the compensating value for a fuel injection volume, and which can obtain an optimum air-fuel ratio even during purging. CONSTITUTION:An internal combustion engine incorporates a canister 2 which can temporarily trap therein fuel vapor from a fuel tank 23, and to which a galvanic battery type oxygen sensor 1 is attached. Accordingly, an oxygen density (oxygen partial pressure) detected by the sensor 1 is transmitted to a control device 8 for calculating a density of fuel vapor gas contained in purged gas from an detection output from the sensor 1, and for controlling a compensating value for the fuel injection value in accordance with thus calculated density. That is, when the density of the fuel vapor gas is high, the compensating value is controlled so as to decrease the fuel injection volume in accordance with the detected density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine having a canister for temporarily storing evaporated fuel from a fuel tank.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a conventional control apparatus for an internal combustion engine disclosed in Japanese Patent Laid-Open No. 1-310156. In the figure, 2 is a canister having an adsorption layer 18 of activated carbon or the like inside, 17 is an air introduction passage, 4 is a pipe connected to a fuel tank, 6 is a pipe serving as a purge passage of the canister 2, and 16 is a heater built-in oxygen It is a density sensor.
5 is an engine intake pipe, 12 is a throttle valve, 13 is an intake pipe pressure sensor, 14 is an engine, 7 is an injector,
Reference numeral 15 is a rotation speed sensor, 19 is an output processing circuit, and 20 is a microcomputer.

The oxygen concentration sensor 16 attached to the canister 2 detects the amount of fuel vapor introduced into the intake pipe 5 during purging of the canister, and controls the injector 7 based on the detected output. This system is a D-T type fuel injection equipped with an intake pipe pressure sensor 13, and FIG. 4 shows a flowchart of the fuel injection control.

In step S1, the basic fuel injection amount TP0 is calculated from the map of the intake pipe pressure PM and the engine speed NE from the engine speed sensor 15. Next, step S
At 2, the oxygen concentration VP0 of the gas introduced from the inside of the canister 2 into the intake pipe 5 when the fuel vapor gas concentration is 0% is calculated from the map of the intake pipe pressure PM and the engine speed NE.

Next, at step S3, the fuel injection amount TP is calculated from the output VP of the oxygen concentration sensor 16 as TP = TP0 × (VP
/ VP0) × a + b. Where VP /
VP0 corresponds to the fuel vapor concentration. That is, the correction is performed so that the fuel actually injected decreases as the amount of the evaporated fuel introduced increases. a and b are factors that are appropriately selected so that optimum correction is performed. Next, step S
In 4, the signal output processing is performed so that the calculated amount of fuel is injected from the injector 7.

FIG. 5 shows the structure of the oxygen concentration sensor 16. In the figure, a substrate 27, a main body 23 made of a solid electrolyte such as zirconia placed on the substrate 27 via a spacer 21, electrodes 22 and 25 formed on both surfaces of the main body 23, and an air-fuel ratio detection gas It is composed of a porous ceramic 24 as a gas diffusion layer that covers the periphery of the side electrode 22 and a heater 26 for keeping the main body 23 at a high temperature of 700 to 900 ° C. at all times. By applying a voltage between the electrodes 22 and 25, O2-ions flow at a diffusion rate determined by the oxygen partial pressure and the diffusion layer 24. As described above, the limiting current type oxygen sensor can detect the oxygen partial pressure by the limiting current.

[0007]

Since the conventional control device for the internal combustion engine is constructed as described above, it has the following problems. That is, the oxygen concentration sensor 16 employs a solid electrolyte, and a heater or the like is used to keep the temperature between 700 and 90.
Since the oxygen concentration cannot be detected unless it is kept at a high temperature of 0 ° C, there is a safety problem in using it in explosive dangerous gas such as fuel vapor gas. Further, in terms of cost, there is a problem that the oxygen concentration sensor 16 is expensive.

The present invention has been made in order to solve such a problem, and safely and inexpensively detects the fuel vapor gas concentration in the purge gas, and controls the correction amount of the fuel injection amount or the purge amount accordingly. Accordingly, it is an object of the present invention to provide a control device for an internal fuel engine that can obtain an optimum air-fuel ratio even during purging.

[0009]

According to a first aspect of the present invention, there is provided a control device for an internal combustion engine, wherein the internal combustion engine includes a canister for temporarily storing evaporated fuel from a fuel tank, and the oxygen concentration in the canister is controlled. It has a galvanic cell type oxygen concentration sensor for detecting, and means for correcting the fuel injection amount of the internal combustion engine based on the output of this concentration oxygen sensor.

In a control device for an internal combustion engine according to a second aspect of the present invention, the internal combustion engine includes a canister for temporarily storing evaporated fuel from a fuel tank, and a galvanic cell type oxygen for detecting the oxygen concentration in the canister. It has a concentration sensor and means for controlling the purge amount of the canister based on the output of the oxygen concentration sensor.

[0011]

According to the first aspect of the invention, the oxygen concentration in the canister is detected by the galvanic cell type oxygen concentration sensor to calculate the fuel vapor gas concentration contained in the purge gas,
With this, the correction amount of the fuel injection amount is controlled, and the galvanic cell type oxygen concentration sensor does not have to keep the temperature always high unlike the conventional oxygen concentration sensor, and the fuel vapor gas concentration in the purge gas can be detected safely and inexpensively. It is possible to obtain an optimum air-fuel ratio even during purging.

According to the second aspect of the present invention, the oxygen concentration of the canister is detected by a galvanic cell type oxygen concentration sensor to calculate the fuel vapor gas concentration contained in the purge gas, and the purge amount of the canister is controlled thereby. Unlike the conventional oxygen concentration sensor, the galvanic cell type oxygen sensor does not need to be kept at a high temperature all the time, and the fuel vapor gas concentration in the purge gas can be detected safely and inexpensively, and the optimum air-fuel ratio can be obtained even during purging. It becomes possible.

[0013]

【Example】

Example 1. FIG. 1 is a block diagram showing an embodiment of a control device for an internal combustion engine according to the present invention. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals. In the figure, 2 is a canister for temporarily storing the evaporated fuel from the fuel tank 3, 17 is an atmosphere introduction passage, 4 is a pipe connecting the fuel tank 3 and the canister 2, 6 is a canister 2 and an intake pipe 5. This is the pipe that connects the two. Reference numeral 1 denotes a galvanic cell type oxygen concentration sensor attached to the canister 2, and supplies a detection output of the oxygen partial pressure detected by the oxygen concentration sensor 1 to the control device 8. Reference numeral 7 denotes a fuel injection device attached to the intake pipe 5, and the fuel injection amount is controlled by the control device 8. Reference numeral 9 is an air cleaner connected to the intake pipe 5.

Next, the operation will be described. The fuel vapor gas generated in the fuel tank 3 is stored in the canister 2 through the pipe 4. When this fuel vapor gas is introduced into the intake pipe 5 of the engine together with the air from the atmosphere introduction passage 17 of the canister 2, the oxygen concentration (oxygen partial pressure) in this air is detected by the oxygen concentration sensor 1.

Here, the relationship between the fuel vapor gas concentration and the oxygen concentration is as follows. Oxygen concentration in the atmosphere is about 20
%, And assuming that the fuel vapor gas concentration in the canister 2 is x%, the oxygen concentration in the canister 2 is Po = (20−
x / 5)%. Therefore, the fuel vapor gas concentration x is x = (100-5
Po)% is required.

From the oxygen concentration detected by the oxygen concentration sensor 1, the fuel vapor gas concentration is calculated by the above equation. When the fuel vapor gas concentration is high, the correction amount is controlled so as to reduce the amount of fuel injected from the fuel injection device 7 according to the concentration.

Example 2. In the example of FIG. 1, the correction amount of the injection amount injected from the fuel injection device 7 is controlled according to the detection output of the galvanic cell type oxygen concentration sensor 1, but
As shown in FIG. 2, the valve 1 is connected to the pipe 6 which is the purge passage.
By setting 0 and controlling the purge amount, the same effect as the example of FIG. 1 can be obtained. That is, the valve 10 is opened and closed so as to control the purge amount according to the detection output of the oxygen sensor 1 attached to the canister 2. In order to control the valve 10, the control device 8 detects the operating state of the engine, and when the fuel vapor gas concentration is high, the purge amount is reduced to perform the purge so that the influence of the purge is small, and the engine operation is performed. Purge is performed when the effect of purging is small in this state.

[0018]

According to the invention of claim 1, the internal combustion engine comprises a canister for temporarily storing the evaporated fuel from the fuel tank, and a galvanic cell type oxygen concentration sensor for detecting the oxygen concentration in the canister. , A means for correcting the fuel injection amount of the internal combustion engine based on the output of the oxygen concentration sensor, and detects the oxygen concentration of the canister by a galvanic cell type oxygen sensor to determine the fuel vapor gas concentration contained in the purge gas. The oxygen concentration sensor of galvanic cell type does not need to be kept at a high temperature unlike the conventional oxygen concentration sensor because it calculates and controls the correction amount of the fuel injection amount accordingly, and the concentration of fuel vapor gas in the purge gas can be safely and inexpensively There is an effect that it can be detected and an optimum air-fuel ratio can be obtained even at the time of purging.

According to the second aspect of the invention, the internal combustion engine comprises a canister for temporarily storing the evaporated fuel from the fuel tank, and a galvanic cell type oxygen concentration sensor for detecting the oxygen concentration in the canister, and And a means for controlling the purge amount of the canister based on the output of the oxygen concentration sensor, the oxygen concentration of the canister is detected by a galvanic cell type oxygen concentration sensor to calculate the fuel vapor gas concentration contained in the purge gas, Since the purge amount of the canister is controlled by it, the galvanic cell type oxygen concentration sensor does not need to keep the temperature always high unlike the conventional oxygen concentration sensor, and the fuel vapor gas concentration in the purge gas can be detected safely and inexpensively. There is an effect such that an optimum air-fuel ratio can be obtained even at times.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a control device for an internal combustion engine according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment of a control device for an internal combustion engine according to the present invention.

FIG. 3 is a configuration diagram showing a conventional control device for an internal combustion engine.

FIG. 4 is a flowchart showing a conventional fuel injection control operation.

FIG. 5 is a sectional view showing a schematic configuration of a conventional oxygen concentration sensor.

[Explanation of symbols]

 1 Galvanic Battery Oxygen Concentration Sensor 2 Canister 3 Fuel Tank 4, 6 Piping 5 Intake Pipe 7 Fuel Injector 8 Control Device 9 Air Cleaner 10 Valve 12 Throttle Valve

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[Procedure amendment]

[Submission date] June 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

The oxygen concentration sensor 16 attached to the canister 2 detects the amount of fuel vapor introduced into the intake pipe 5 during purging of the canister, and controls the injector 7 based on the detected output. This system is a fuel injection system based on the D- J method equipped with the intake pipe pressure sensor 13, and FIG. 4 shows a flowchart of the fuel injection control.

Claims (2)

[Claims] 1. An internal combustion engine having a canister for temporarily storing evaporated fuel from a fuel tank, wherein a galvanic cell type oxygen concentration sensor for detecting oxygen concentration in the canister and an output of the oxygen concentration sensor are used. A control device for an internal combustion engine, comprising: means for correcting the fuel injection amount of the internal combustion engine. 2. An internal combustion engine having a canister for temporarily storing evaporated fuel from a fuel tank, wherein a galvanic cell type oxygen concentration sensor for detecting the oxygen concentration in the canister and an output of the oxygen concentration sensor are used. A control device for an internal combustion engine, comprising: means for controlling a purge amount of the canister.