JPH055431A - engine - Google Patents

Abstract

(57) [Summary] [Purpose] To lower the temperature inside the cylinder and improve thermal efficiency. [Configuration] The engine 1 has a sub chamber 10, and the sub chamber 10
The sub-chamber port 10a is open to the combustion chamber 4. The sub-chamber port 10a is opened and closed by the sub-chamber valve 11, and the closing timing of the sub-chamber valve 11 is set between the end of the compression stroke where the temperature in the cylinder rises and the initial stage of the explosion stroke. On the other hand, the opening timing of the sub-chamber valve 11 is set to the middle of the compression stroke, whereby the air-fuel mixture cooled in the sub-chamber 10 is replaced with a part of the air-fuel mixture in the combustion chamber 4, and the in-cylinder temperature decreases. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine, that is, an internal combustion engine, and more particularly to an engine for improving thermal efficiency of the engine.

[0002]

2. Description of the Related Art In an engine, that is, an internal combustion engine, a mechanical work is taken out by utilizing a pressure increase due to combustion of fuel supplied to a combustion chamber. Therefore, the larger the pressure increase ΔP (in-cylinder pressure increase) associated with combustion, the better the work.

Now, the calorific value Q of fuel is expressed by the following equation. Q = Cv ・ G ・ △ T ・ ・ ・ (1)

Here, Cv: constant volume specific heat G: mass of air-fuel mixture introduced into the combustion chamber ΔT: temperature rise due to combustion (increase in cylinder temperature)

When the above equation (1) is modified, the following equation (2) is obtained. ΔT = Q / Cv · G (2) As can be understood from the equation (2), when Q and G are constant, the smaller Cv is, the larger ΔT is.

By the way, it is known that the constant volume specific heat Cv increases substantially in proportion to the in-cylinder temperature T (see FIG. 1). In other words, the smaller the in-cylinder temperature T, the constant volume specific heat C
v is small. Therefore, the smaller the in-cylinder temperature T is, the larger the increase ΔT in the in-cylinder temperature due to combustion is.

Here, the larger the temperature rise ΔT in the cylinder is,
Since the cylinder pressure greatly increases (ΔP is large),
The smaller the in-cylinder temperature T, the greater the increase in the in-cylinder pressure ΔP. In other words, put the same amount of fuel,
When the obtained calorific values are the same, the smaller the in-cylinder temperature T is, the larger the in-cylinder pressure increase ΔP is, and therefore the better the work is performed (the better the thermal efficiency is).

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an engine in which the temperature inside the cylinder is small and the thermal efficiency is improved.

[0009]

In order to achieve the above technical object, according to the present invention, a sub-chamber formed in the engine body and opening to the combustion chamber, and a sub-chamber for opening and closing the opening of the sub-chamber. A valve, the sub-chamber valve being opened in the middle of the compression stroke and closed during the end of the compression stroke or the beginning of the explosion stroke.

[0010]

With the above structure, the hot air-fuel mixture due to compression is enclosed in the sub chamber and cooled in the sub chamber. Then, the air-fuel mixture cooled in the sub chamber is replaced with a part of the air-fuel mixture in the combustion chamber in the next compression stroke, and as a result, the air-fuel mixture in the combustion chamber is cooled (the temperature inside the cylinder decreases). Therefore, the higher the temperature of the air-fuel mixture introduced into the sub-chamber, the greater the cooling effect in the sub-chamber, which makes it possible to greatly reduce the in-cylinder temperature.

When considering the closing timing of the sub-chamber valve, if the temperature rise due to compression of the air-fuel mixture in the combustion chamber is to be utilized to the maximum, the closing timing of the sub-chamber valve is referred to as compression top dead center. do it. Alternatively, if the pressure increase due to combustion is also used to the maximum extent, it is better to close the sub-chamber valve as late as possible (the crank angle reaching the maximum combustion pressure is about 30 deg after compression top dead center (ATDC)).

[0012] Here, the actual combustion state fluctuates greatly in each cycle as shown in the acupressure diagram of FIG.
Therefore, if the sub chamber valve was opened until the deviation (variation) of the in-cylinder pressure was large, the pressure, density, and temperature of the air-fuel mixture trapped in the sub chamber would fluctuate in each cycle. Not preferable.

Considering FIG. 2 from this point of view, in the example of the engine specifications and operating conditions shown in FIG. 2, the pressure fluctuation in the combustion chamber occurs about 20 degrees after the ignition timing.
It is after a while. Therefore, if the sub-chamber valve is closed immediately before the deviation (variation) of the pressure increase due to combustion occurs, it is possible to suppress the influence of combustion fluctuation and enhance the cooling effect of the air-fuel mixture.

On the other hand, in order to prevent the influence of the pressure fluctuation due to combustion, the sub chamber valve may be closed near the ignition timing. That is, the sub chamber valve may be closed at the end of the compression stroke.

Specifically, the opening timing of the sub chamber valve may be determined in relation to the closing timing of the sub chamber valve. That is, even if the sub-chamber valve is opened, the air-fuel mixture in the sub-chamber cannot be immediately replaced with the air-fuel mixture in the combustion chamber. This replacement requires some time. However, when the sub chamber valve is opened too early, the compression stroke is performed under the volume of the combustion chamber plus the volume of the sub chamber, resulting in a large compression loss.

Therefore, the opening timing of the sub-chamber valve may be set as late as possible after entering the compression stroke (after closing the intake valve) and at a timing that can secure the time required to replace the air-fuel mixture in the sub-chamber. The opening timing of this sub-chamber valve is in the middle of the compression stroke. Of course, the opening timing of the sub chamber valve may be finally determined by an experiment.

As prior arts structurally similar to the present invention, Japanese Patent Laid-Open Nos. 54-116512 and 54-9 are available.
There is an engine with a sub chamber disclosed in Japanese Patent No. 80408.
This engine with a sub-chamber includes a sub-chamber that opens to the combustion chamber and a sub-chamber valve that opens and closes the opening of the sub-chamber, and this point is common to the present invention.

However, in this engine with a sub-chamber, the sub-chamber valve is opened according to the closing timing of the intake valve, and the air-fuel mixture in the sub-chamber is used (by utilizing the differential pressure between the sub-chamber and the combustion chamber). ),
The present invention differs from the present invention in that a strong swirl is generated in the combustion chamber.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Reference numeral 1 shown in FIG. 3 is an engine, and the engine 1 has a combustion chamber 4 defined by a piston 3 inserted into a cylinder bore 2, and an ignition plug 5 is disposed so as to face the combustion chamber 4. ing.

An intake port 6 and an exhaust port 7 are opened in the combustion chamber 4, and an intake valve 8 is provided in the intake port 6.
The exhaust port 7 is provided with an exhaust valve 9, and the intake valve 8 and the exhaust valve 9 are opened and closed at a predetermined timing in synchronization with an engine output shaft (not shown). It That is, the engine 1 is a conventionally known Otto-cycle gasoline 4-cycle engine.

The engine 1 has a sub chamber 10.
The sub-chamber 10 has a sub-chamber port 10a opened to the combustion chamber 4, and a sub-chamber valve 11 is arranged in the sub-chamber port 10a. With the sub-chamber valve 11, the sub-chamber port 10a is opened. It is designed to be opened and closed.

An example of the opening / closing timing of the sub chamber valve 11 is shown in FIG. As is clear from FIG. 4, the sub-chamber valve 11
Is an ABD whose closing timing is the same as ignition timing
It is set to C160deg, which is about 7 times longer than this closing timing.
The sub chamber valve 11 is designed to be opened before 0 deg. The closing timing of the intake valve 8 is about 5 after the top dead center has passed.
It is set to 0 deg.

With the above construction, a part of the air-fuel mixture in the combustion chamber 4 is confined in the sub-chamber 10 by the sub-chamber valve 11 opened and closed in the compression stroke, cooled in the sub-chamber 10, and the next In the compression stroke, the air-fuel mixture cooled in the sub chamber 10 is replaced with a part of the air-fuel mixture in the combustion chamber 4.

As a result, the temperature of the air-fuel mixture in the combustion chamber 4 (in-cylinder temperature) becomes lower than that of a normal engine having no sub-chamber 10, and the thermal efficiency of the engine 1 is improved.

Further, the fact that the temperature inside the cylinder decreases means that
This is also advantageous as a countermeasure against knocking. Therefore, it is also effective as a countermeasure against knocking when increasing the compression ratio of the engine or increasing the supercharging pressure.

Although the Otto-cycle type engine has been described above as an example, the present invention can be applied to a diesel engine. When applied to this diesel engine, there is an effect that NO _X in the exhaust gas can be reduced in addition to improvement of thermal efficiency.

[0027]

As is apparent from the above description, according to the present invention, the thermal efficiency of the engine can be improved by lowering the temperature inside the cylinder.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an in-cylinder temperature and a specific heat (constant volume specific heat) of an air-fuel mixture.

FIG. 2 is a typical acupressure diagram of an engine.

FIG. 3 is a schematic diagram of an engine according to an embodiment.

FIG. 4 is a diagram showing an example of opening / closing timing of a sub chamber valve.

[Explanation of symbols]

 1 Engine 3 Piston 4 Combustion Chamber 5 Spark Plug 8 Intake Valve 10 Subchamber 10a Subchamber Port 11 Subchamber Valve Opening to Combustion Chamber

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Kashiyama, 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor, Junzo Sasaki 3-3-1 Shinchu, Fuchu-cho, Hiroshima Prefecture Mazda Stock In the company

Claims (1)

Claim: What is claimed is: 1. A sub-chamber, which is formed in the engine body and opens to the combustion chamber, and a sub-chamber valve that opens and closes the opening of the sub-chamber, wherein the sub-chamber valve is a compression stroke. Opened in the middle of
An engine characterized by being closed during the end of the compression stroke or the beginning of the explosion stroke.