JP4707651B2 - An internal combustion engine using alcohol-based fuel - Google Patents

Description

  The present invention relates to an internal combustion engine using a fuel containing alcohol as a main component, such as alcohol such as ethanol, or a mixed fuel oil obtained by mixing gasoline or kerosene or the like with alcohol as a main component. Is intended to reliably start the internal combustion engine.

  In recent years, due to air pollution and fluctuations in crude oil conditions, alcohol has been used as a fuel for internal combustion engines, such as alcohol, such as ethanol, or mixed fuel oils, such as gasoline or kerosene mixed with alcohol as the main component. It has been proposed to use fuel as the main component.

  However, alcohol has the advantage that it has a higher octane number than gasoline, but has a low calorific value and a high boiling point, flash point, and latent heat of vaporization. When the engine is used in an internal combustion engine, its startability is considerably lower than when gasoline is the main fuel.

In this case, in Patent Documents 1 and 2 as the prior art, when starting the internal combustion engine, first, the intake air amount control valve such as a throttle valve is closed to reduce the pressure in the intake passage, and the fuel is reduced in this reduced pressure state. The fuel is made finer and vaporized by injecting the fuel, and when the initial ignition of the fuel is confirmed, the intake amount control valve is opened to reduce the pressure reduction in the intake passage. Describes a technique for improving startability in an internal combustion engine.
Japanese Utility Model Publication No. 01-119874 Japanese Utility Model Publication No. 58-151332

  However, when this prior art is applied to an internal combustion engine using alcohol as a main component, alcohol has a considerably higher boiling point, flash point, and latent heat of vaporization than gasoline. Since the intake air amount control valve is opened in response to detection of the initial ignition of fuel and a large amount of new intake air is inhaled, the refinement and vaporization of the alcohol rapidly deteriorate. There is a problem that engine stall occurs without starting the internal combustion engine.

  In particular, the engine stall at the start occurred more frequently as the temperature was lower.

  It is a technical object of the present invention to solve this problem.

In order to achieve this technical problem, claim 1 of the present invention provides:
“In an internal combustion engine that is operated with fuel containing alcohol as its main component, when starting the engine, the intake passage is depressurized by closing the intake air amount control valve, and fuel is injected. When ignition is detected, the pressure reduction in the intake path is reduced by opening the intake air amount control valve, and the control means in the intake air amount control valve is configured to open the intake air amount control valve. The speed is reduced as the temperature of the internal combustion engine is lower . "
It is characterized by that.

Further , claim 2 of the present invention is
"In the device according to claim 1, the detection of the initial ignition fuel, is the detection of the ion current in the combustion chamber."
It is characterized by that.

In an internal combustion engine that is operated with a fuel containing alcohol as a main component, when the engine is started, the inside of the intake passage is depressurized by closing the intake air amount control valve, and fuel is injected, and then the initial ignition of the fuel is performed. In the case where the pressure reduction in the intake path is reduced by the opening operation of the intake air amount control valve in response to the detection of the intake air, the new intake air after the initial ignition of the fuel is achieved by opening the intake air amount control valve. Inhalation is gradually performed.

  As a result, the refinement and vaporization of the alcohol-based fuel can be reduced from sudden deterioration due to the intake of new intake air, so that the occurrence of engine stall at the start can be reliably reduced. The startability of can be improved.

In particular, since the refinement and vaporization of the fuel containing alcohol as a main component becomes worse as the temperature is lower, the speed at which the intake air amount control valve is opened during start-up as described in claim 1 is increased. , By making the speed slower as the temperature is lower, the startability of the internal combustion engine from a low temperature state can be improved more reliably.

  In this case, the temperature is not limited to the temperature in the internal combustion engine itself, but may of course be the temperature of the atmospheric air or the temperature of the coolant for the internal combustion engine.

In addition, the detection of the ionic current described in claim 2 can reliably detect an initial ignition state that does not appear in a change in the rotation and load of the internal combustion engine, and the accuracy of detecting the initial ignition is improved. Since it can be greatly improved, there is an advantage that the above-mentioned effects can be promoted accurately.

  An embodiment of the present invention will be described below with reference to the drawing of FIG.

  In this figure, reference numeral 1 denotes a multi-cylinder internal combustion engine having a plurality of cylinders 3 with respect to a single crankshaft 2. The side of the internal combustion engine 1 is guided by an intake passage 4 from an air cleaner (not shown). An intake manifold 5 for distributing new intake air to the cylinders 3 is connected to the intake manifold 5 for injecting and supplying fuel mainly composed of alcohol to each of the cylinders 3. A main fuel injection valve 6 is provided for each cylinder 3.

  A throttle body 8 having a throttle valve 7 is provided in the middle of the intake passage 4, and an idle passage 9 for bypassing the throttle valve 7 is provided. A bypass valve 10 is provided in the middle of the idle passage 9. Is provided, and the internal combustion engine 1 is idled by opening the bypass valve 10 with the throttle valve 7 closed.

  A start fuel injection valve 11 is attached to a portion of the intake passage 4 downstream of the throttle valve 7 so as to inject and supply a fuel containing alcohol as a main component into the intake passage 4 as a start fuel. The starting fuel injection valve 11 can be provided in the collecting pipe portion of the intake manifold 5 or can be provided in the idle passage 9 on the downstream side of the bypass valve 10.

  Then, the start fuel injection valve 11, the throttle valve 7 and the bypass valve 10, the ignition signal (not shown) for starting the internal combustion engine 1, the start signal 12 for switching on, the temperature sensor in the internal combustion engine 1 13. Control is performed as described below by a controller 15 that receives a signal from an ion current sensor 14 provided in a combustion chamber of at least one cylinder 3 or a plurality of cylinders among the cylinders 3.

  That is, when the start signal 12 is input thereto, the controller 15 first completely closes the throttle valve 7 and the bypass valve 10, and in this state, the crankshaft 2 is rotated so that the intake passage 4 is rotated. The inside is made highly decompressed, and then the starting fuel injection from the starting fuel injection valve 11 is started.

  When the ionic current sensor 14 detects the initial ignition of the fuel after injecting and supplying the starting fuel, the bypass valve 10 is opened to the idle opening degree. Configure to do at speed.

  In this way, when the start of the internal combustion engine 1 is confirmed, the fuel injection supply is switched from the starting fuel injection valve 11 to the main fuel injection valve 6.

  At the time of starting, when the bypass valve 10 is opened according to the detection of the initial ignition of the fuel by the ion current sensor 14, the opening operation is performed at a moderate speed, so that after the initial ignition of the fuel. New intake air is gradually inhaled, which makes it possible to reliably avoid the rapid deterioration of fuel refinement and vaporization caused by the intake of new intake air. That can be reliably reduced.

  The controller 15 receives a signal from the temperature sensor 13 for the internal combustion engine 1 and slows down the speed when the bypass valve 10 is opened to the idle opening when the temperature of the internal combustion engine 1 is low at the start. It is configured to control so as to.

  As a result, the startability of the internal combustion engine from a low temperature state can be reliably improved.

  The control in this case is not limited to the temperature in the internal combustion engine 1 itself, but may depend on the temperature of the atmospheric air or the temperature of the coolant for the internal combustion engine.

  In the above embodiment, when the internal combustion engine 1 is started, the bypass valve 10 for the throttle valve 7 is controlled. The bypass valve 10 is eliminated and only the throttle valve 7 is controlled as described above. It can also be configured to.

  Further, the starting fuel injection valve 11 in the above embodiment can be eliminated, and the main fuel injection valve 6 can be configured to inject and supply the starting fuel.

  Furthermore, the refinement and vaporization of the alcohol-based fuel is bad when the rotational speed at the start is slow and when the load is low. The speed at which the intake air amount control valve such as the bypass valve 10 or the throttle valve 7 is opened is controlled so as to be slow when the rotational speed at the start is slow and when the load is low. As a result, the startability of the internal combustion engine can be further improved.

It is a figure which shows embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Crankshaft 3 Cylinder 4 Intake passage 5 Intake manifold 6 Main fuel injection valve 7 Throttle valve 10 Bypass valve 11 Fuel injection valve for starting 13 Temperature sensor 14 Ion current sensor 15 Controller

Claims (2)

In an internal combustion engine that is operated with a fuel containing alcohol as a main component, when the engine is started, the inside of the intake passage is depressurized by closing the intake air amount control valve, and fuel is injected, and then the initial ignition of the fuel is performed. The pressure reduction in the intake path is reduced by opening the intake air amount control valve when the intake air amount is detected, and the control means in the intake air amount control valve is configured to open the intake air amount control valve. An internal combustion engine using an alcohol-based fuel, characterized in that the speed is reduced as the temperature of the internal combustion engine is lower . 2. An internal combustion engine using a fuel mainly comprising alcohol according to claim 1, wherein the detection of the initial ignition of the fuel is detection of an ionic current in the combustion chamber .

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