JPS5813736B2 - gasoline - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Generally, combustion in a four-cycle gasoline engine is carried out from near the end of the compression stroke to the beginning of the expansion stroke, and is known to be a constant-volume or nearly constant-volume constant-pressure complex combustion.

Furthermore, if the thermal efficiency of the cycle is constant, it can be easily confirmed using thermodynamic relations that the maximum temperature of the cycle decreases as it approaches constant-pressure combustion from constant-volume combustion if the compression ratio is appropriately selected. can.

On the other hand, it is currently a well-known technical matter that the weight of nitrogen oxides produced among the exhaust gas components is almost uniquely determined by the maximum temperature of the cycle.

By the way, the combustion speed of a conventional gasoline engine with a homogeneous mixture is a physical quantity determined by the mixture properties in the combustion chamber at the time of ignition and other factors, and it is difficult to freely control this.
It was impossible.

In particular, depending on the shape of the combustion chamber, the position of the spark plug, etc.
Although it could be varied slightly, this was not sufficient to control the formation of nitrogen oxides.

Therefore, from the final stage of the compression stroke to the beginning stage of the expansion stroke, combustion is divided into two stages and combustion is controlled to perform essentially constant-pressure combustion to remove nitrogen oxides from the exhaust gas. It is conceivable to reduce the weight.

The present invention aims to maintain constant-pressure combustion as much as possible by selecting the ignition timing when using a lean mixture in such a split-combustion internal combustion engine, and to prevent a decrease in thermal efficiency.
The purpose of this invention is to provide a gasoline infield engine that has been improved to avoid a decrease in output as much as possible.

For this purpose, the present invention has a sub-piston part protruded from the top of the piston so as to divide the field burning chamber into first and second combustion chambers for a predetermined period before and after the top dead center, The cylinder head is provided with four parts for forming a first combustion chamber which are recessed from the second combustion chamber and into which the auxiliary piston part is fitted, and the ignition plug provided in the first combustion chamber is energized and ignited by the piston. Set before the division of the second combustion chamber division period, and with a uniform lean mixture being sucked into both combustion chambers, the spark plug ignites the mixture in the first combustion chamber and enters the expansion stroke. This is characterized in that the first and second combustion chambers are brought into communication by the lowering of the piston, and the flame propagates and ignites in the second combustion chamber.

Embodiments of the present invention will be specifically described below with reference to the drawings.

In the figure, reference numeral 1 denotes a cylinder head connected to the cylinder 2, which has a circular shape biased toward one side of the recess forming the second combustion chamber 5 to form the first melting chamber 4. Correspondingly, a sub-piston part 3a is integrally formed at the top of the piston 3 to be slidably fitted thereto.

As the piston 3 rises, the auxiliary piston portion 3a divides the inside of the cylinder into a first combustion chamber 4 and a second combustion chamber 5 which are independent from each other.

The first combustion chamber 4 is provided with a spark plug 6, and the other second combustion chamber 5 is provided with an intake passage 7 and an exhaust passage 8.
are in communication with each other, and a poppet-type intake valve 9 and an exhaust valve 10 are provided at the communication points, respectively.

Therefore, the only difference from the conventional cylinder structure is the internal shape of the cylinder head and the shape of the top of the piston, which is extremely simple.

Therefore, the operation of the internal combustion engine configured as described above is such that during the intake stroke in which the piston 3 moves toward the bottom dead center, the intake valve 9 is open and the air-fuel mixture is introduced into the cylinder 2 from the intake passage 7. Then, when the piston 3 passes the bottom dead center and enters the compression stroke, the intake valve 9 is closed.

As the compression stroke progresses, the sub piston part 3a moves to the cylinder head 1.
When the cylinder enters the recess, the inside of the cylinder is divided into the first combustion chamber 4 and the second combustion chamber 5. This time is before top dead center, and the crank angle is θ.

Therefore, the period during which the first combustion chamber and the second combustion chamber are divided is 2θ around the tenth dead center, and the air-fuel mixture in both combustion chambers is subjected to the turbirence effect during this division period and the communication period.

In the present invention, the divided period is 20 hours before and after top dead center.
0, that is, for the divided period shown in FIG. 2 where θ=20°,
energizing the spark plug 6 during the period θe before the division;
Set the ignition timing to ignite.

Note that the ignition timing of the ignition plug 6 is controlled to be advanced or retarded according to the rotational speed of the engine as in a normal internal combustion engine, but this control is performed before the above-mentioned division.

In this way, the ignition in the first combustion chamber 4 is accelerated by the activation and ignition of the spark plug 6, and the ignited flame is propagated to the lean mixture in the first combustion chamber 4.
It is possible to eliminate the delay in arrival of the flame brought to the communication portion between the first combustion chamber 4 and the second combustion chamber 5.

In other words, when the flame ignited by the spark plug 6 is propagated into the air-fuel mixture in the first combustion chamber 4 and brought to the communication section between the first combustion chamber 4 and the second combustion chamber 5, there is a delay in reaching the flame. However, in the present invention, this delay in arrival of the flame is taken into account,
By setting the energization of the spark plug 6 and the ignition before division, the ignition in the first combustion chamber 4 is accelerated, and therefore the expansion stroke begins and the first combustion chamber 4 and the second combustion chamber 5 are connected. When the communication occurs, a powerful flame that has grown sufficiently from the communication part at the right time is ignited from the first combustion chamber 4 to the lean mixture in the second combustion chamber 5, and the second field burning chamber 5 is ignited.
Since a strong turbulence is applied to the lean air-fuel mixture in the combustion chamber, ignition is ensured without fear of misfire, and combustion in the second combustion chamber 5 is performed stably before entering the exhaust stroke.

Note that even if the spark plug is activated before the first and second combustion chambers 4 and 5 are divided, the air-fuel mixture on the second combustion chamber 5 side is
Since it is a lean mixture and is spaced apart from the spark plug, the mixture in the second combustion chamber will not be ignited at the same time.

The combustion in the first combustion chamber 4 during the division period is performed as described above, but the mixture is lean and the combustion is performed in multiple stages. thing,
Together, this suppresses the rise in the maximum furnace temperature and the rise in pressure, resulting in almost constant pressure combustion and reducing the generation of nitrogen oxides in the exhaust gas.

As described in detail below, this invention divides the combustion chamber into two chambers by a piston for a predetermined period before and after top dead center in the cylinder, and activates the spark plug in the first combustion chamber and controls the ignition. , is set before the dividing period of the combustion chamber by the piston, and when the ignition plug ignites the lean mixture in the first combustion chamber and the lowering of the piston communicates the first combustion chamber and the second combustion chamber, Since the second combustion chamber is also ignited by blowing out a torch-type flame, combustion occurs in multiple stages, bringing the combustion form close to constant-pressure combustion, suppressing the maximum pressure and temperature of initial combustion, and reducing NOx (7). Although it has the characteristic of split combustion that can suppress combustion, there is no delay in the flame reaching the second combustion chamber from the first combustion chamber, and the flame propagation speed in the first combustion chamber and the second combustion chamber is high. Therefore, it is possible to minimize the decrease in output.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the present invention, and FIG. 2 is a chart showing the relationship between the crank angle and the division of the combustion chamber by the piston. 1...Cylinder head, 2...Cylinder, 3...Piston, 3a...Sub-piston part, 4, 5...Combustion chamber, 6...
Spark plug, 7...Intake passage, 8...Exhaust passage, 9...
Intake valve, 10...exhaust valve.

Claims (1)

[Claims] 1. An auxiliary piston part is protruded from the top of the piston and attached to the cylinder head so as to divide the combustion chamber into independent first and second combustion chambers for a predetermined period before and after the top dead center. A recess for forming a first combustion chamber is provided which is recessed from the second combustion chamber and into which the auxiliary piston part is inserted. Set before the division of the combustion chamber division period, and with a uniform lean mixture sucked into both combustion chambers, the spark plug ignites the mixture in the first combustion chamber and enters the expansion stroke, causing the piston to move. The fiber 1 and the second combustion chamber communicate with each other by descending, and the flame propagates and ignites in the second combustion chamber. Gasoline internal combustion engine.