JP3647355B2 - Operation method of sub-chamber combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention supplies a sub-chamber fuel to a sub-combustion chamber provided in a cylinder head, ignites the sub-chamber fuel supplied to the sub-combustion chamber with a spark plug, and a plurality of nozzle holes from the sub-combustion chamber It is related with the operating method of the subchamber combustion type engine which ejects a flame torch to a main combustion chamber via.
[0002]
[Prior art]
The sub-chamber combustion engine as described above supplies sub-chamber fuel to the sub-combustion chamber via the sub-chamber valve, and sucks fresh air such as air-fuel mixture into the main combustion chamber via the intake valve during the intake stroke. The sub-chamber fuel supplied to the sub-combustion chamber is ignited and burned by a spark plug, and a flame torch is ejected from the sub-combustion chamber to the main combustion chamber through a plurality of nozzle holes to generate a mixture in the main combustion chamber. It burns and maintains the rotation of the crankshaft.
[0003]
During operation of such a sub-chamber combustion type engine, the sub-chamber fuel gas is adjusted by a gas pressure control device or the like so that the pressure becomes higher than the pressure of the intake manifold, and then sub-combustion is performed. It flows into the gas chamber upstream of the sub chamber valve provided in the chamber. The sub chamber fuel gas flows into the sub combustion chamber when the sub chamber valve is opened.
[0004]
On the other hand, in order to realize high efficiency and low NOx combustion in the main combustion chamber, a mixture of fuel and air with a lean fuel amount is drawn as fresh air through the intake valve. When a high voltage is applied to the spark plug by the ignition device linked to the rotational movement of the crankshaft, the sub-chamber fuel gas in the sub-combustion chamber is ignited and burned by the spark discharge from the spark plug. The sub-chamber fuel gas thus ignited is ejected from the nozzle hole into the main combustion chamber as a flame torch, and the lean air-fuel mixture in the main combustion chamber is combusted.
[0005]
Further, in the sub-chamber combustion type engine, the sub-chamber valve is configured as a reed valve provided with a spring member that generates an elastic force in the closing direction, or as a valve that opens and closes using the rotational movement of the crankshaft by a cam mechanism. The opening / closing timing is opened immediately before the TDC timing (time when the piston position becomes top dead center) when the exhaust process is completed, and the sub-chamber fuel gas is supplied to the sub-combustion chamber during the intake stroke, and the compression stroke is performed. When the pressure in the auxiliary combustion chamber becomes almost equal to the gas pressure in the gas chamber after the BDC timing when the piston is started (timing when the piston position is at bottom dead center), supply of fuel gas for the auxiliary chamber Was completed.
[0006]
[Problems to be solved by the invention]
In such a sub-combustion engine, it is necessary to sufficiently mix the sub-chamber fuel gas and the lean air-fuel mixture flowing from the main combustion chamber through the nozzle holes in the compression stroke in the sub-combustion chamber.
If this mixing is not sufficient, uneven fuel concentration occurs in the sub-combustion chamber, and not only does the combustion of the sub-chamber fuel gas in the sub-combustion chamber become unstable, but also the main combustion combusted by the flame torch from the sub-combustion chamber The combustion of the air-fuel mixture in the room also becomes unstable, resulting in a decrease in engine efficiency.
[0007]
Therefore, in view of the above circumstances, the present invention provides a sub-chamber that can sufficiently improve the efficiency by sufficiently mixing the sub-chamber fuel and the fresh air supplied from the main combustion chamber in the sub-combustion chamber. The purpose is to obtain combustion engine operation technology.
[0008]
[Means for Solving the Problems]
[Configuration 1]
The operation method of the sub-chamber combustion engine according to the present invention, as described in claim 1, is to supply the sub-chamber fuel to the sub-combustion chamber by supplying the sub-chamber fuel to the sub-combustion chamber. It is characterized in that it is completed when the piston is descending during the intake stroke.
[0009]
[Function and effect]
As in this configuration, the sub-chamber fuel is supplied to the sub-combustion chamber, and the completion of the supply is the time when the piston is descending during the intake stroke, that is, the time when the crank angle during the intake stroke is before 180 ° ATDC. As a result, it is possible to increase the time from the completion of the supply of the sub chamber fuel to the ignition of the sub chamber fuel by the spark plug at the end of the compression stroke. The sub-chamber fuel can be sufficiently mixed by the lean air-fuel mixture flowing into the combustion chamber.
Therefore, in the sub-chamber combustion type engine, the mixing of the sub-combustion chamber can be made good, the combustion in the sub-combustion chamber and the main combustion chamber can be stabilized, and high-efficiency operation can be realized.
[0010]
Further, the timing for completing the supply of the fuel for the sub-chamber is preferably a timing after the crank angle of 60 ° ATDC at the intake stroke. If the crank angle is completed before the 60 ° ATDC, the sub-chamber is supplied to the sub-combustion chamber. It is difficult to secure sufficient supply of chamber fuel and to obtain sufficient performance, and if the supply pressure of fuel for the sub chamber is set high, the supply amount of fuel for the sub chamber can be secured. Power is increased and the benefits of high efficiency are offset.
Furthermore, the time for completing the supply of the sub chamber fuel is more preferably a time after the crank angle of 150 ° ATDC during the intake stroke, and even if the supply pressure of the sub chamber fuel is set relatively low, the sub chamber fuel supply can be sufficiently performed. The sub chamber fuel can be supplied to the combustion chamber.
[0011]
[Configuration 2]
The sub-chamber combustion engine operating method according to the present invention is, as described in claim 2, in addition to the configuration of the sub-chamber combustion engine operating method of the above configuration 1, the intake valve is opened and closed, and the closing timing is set to the intake timing. A sub-chamber valve for supplying sub-chamber fuel to the sub-combustion chamber is opened and closed by a cam that is a time during which the piston descends during the stroke.
[0012]
[Function and effect]
As in the present configuration, the intake and the valve and the sub-chamber valve in the same cams thus causes opening and closing, timing piston descending during both valves intake stroke, i.e., the crank angle at the time of the intake stroke period of 180 ° ATDC previously closing enough, there is no need to provide a dedicated cams for operating the auxiliary chamber valve, further, by closing the intake valve timing in the downward movement of the piston during the intake stroke, the auxiliary chamber combustion engine, mirror It can be operated in a cycle mode. The Miller cycle method is a method in which knocking is avoided by reducing the in-cylinder compression temperature and pressure by lowering the actual compression ratio depending on the timing of closing the intake valve. As a result, the expansion ratio can be increased and the thermal efficiency can be improved.
Therefore, it is possible to realize a high efficiency sub-chamber combustion engine with an inexpensive and simple structure.
[0013]
In the present application, TDC indicates the top dead center position of the piston, BDC indicates the bottom dead center position of the piston, and the crank angle is expressed by an early / late angle with respect to the TDC. Is shown with BTDC and ATDC in the case of retarded angle.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a method for operating a sub-chamber combustion engine according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a main part showing a combustion chamber and a fuel supply system of a sub-chamber combustion type engine. 1 is a cylinder head, 2 is a main combustion chamber, and the main combustion chamber 2 is a piston 3. The upper surface of the cylinder 4, the inner surface of the cylinder 4, and the lower surface of the cylinder head 1 are partitioned. A lean gas mixture of fuel gas and air, which is a natural gas city gas 13A, is introduced into the main combustion chamber 2 via an intake valve 5.
[0015]
Reference numeral 7 denotes a sub-combustion chamber. The sub-combustion chamber 7 is formed in a substantially central portion of the cylinder head 1 and has a cylindrical shape having an axial direction in the cylinder axial direction. A sub chamber upper metal piece 8 is provided at the upper part of the sub combustion chamber 7, and a sub chamber base 9 is provided at the lower part. One or a plurality of nozzle holes 10 are perforated at the tip of the sub chamber base 9. 11 is a gas chamber formed in the sub-chamber upper hardware 8, and the gas chamber 11 controls the gas pressure of the sub-chamber fuel gas which is the natural gas city gas 13 </ b> A through the gas passage 12. It is connected to a control device (not shown). A sub chamber valve 13 is provided in the sub chamber upper hardware 8 so as to be slidable back and forth, and opens and closes between the gas chamber 11 and the sub combustion chamber 7.
Reference numeral 14 denotes an ignition plug for igniting the fuel gas in the auxiliary combustion chamber 7.
[0016]
During operation of such a sub-chamber combustion type engine, the sub-chamber fuel gas is adjusted by the gas pressure control device so that the pressure becomes higher than the pressure upstream of the intake manifold (not shown). After that, the gas flows into the gas chamber 11 through the gas passage 12 in the sub-chamber upper hardware 8. The sub chamber fuel gas flows into the sub combustion chamber 7 when the sub chamber valve 13 is opened.
[0017]
On the other hand, in order to realize high-efficiency and low NOx combustion, an air-fuel mixture of lean fuel and air is sucked into the main combustion chamber 2 through the intake valve 5 as fresh air. When a high voltage is applied to the spark plug 14 by an ignition device (not shown) that is linked to the rotational movement of the crankshaft (not shown), a spark discharge from the spark plug 14 causes the auxiliary chamber in the sub-combustion chamber 7. Fuel gas ignites and burns. The sub chamber fuel gas thus ignited is ejected from the nozzle hole 10 into the main combustion chamber 2 as a flame torch, and the lean air-fuel mixture in the main combustion chamber 2 is combusted.
[0018]
The sub-chamber combustion engine is configured as a four-cycle engine that completes one cycle through, for example, an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. In the present application, each stroke is a section between TDC and BDC. For example, the intake stroke is the next compression stroke when the intake valve is closed from the time of TDC when the intake valve is opened. Indicates a section up to the time of BDC at which start is started.
[0019]
The above is the description of the basic configuration of the sub-chamber combustion type gas engine. The characteristic configuration of the present invention will be described below.
In the sub-chamber combustion type engine, the sub-chamber valve 13, the intake valve 5, and the exhaust valve 6 are each configured as a valve that is opened and closed by the cam mechanism portion A using the rotational motion of the crankshaft.
As shown in FIG. 2, the cam mechanism A includes a cam shaft 24 that rotates once per cycle by the rotational movement of the crankshaft, cams 21, 22, and 23 provided on the cam shaft 24, and each cam 21. , 22, 23, push rods 25, 26, 27 that reciprocate in the axial direction according to the surface shape, an intake rocker arm 28 that swings around the rocker arm shaft 31 by the push rod 25 to open and close the intake valve 5, and the push rod 26 Is provided with an exhaust rocker arm 29 that swings around the rocker arm shaft 31 to open and close the exhaust valve 6, and a sub chamber rocker arm 30 that swings around the rocker arm shaft 31 by the push rod 27 to open and close the sub chamber valve 13. .
[0020]
Further, the opening / closing timing of the intake valve 5 and the exhaust valve 6 is the same as that of the conventional engine, but the opening / closing timing of the sub chamber valve is as shown in the graph showing the change in the lift amount of the sub chamber valve 13 in FIG. The sub-chamber fuel gas to the sub-combustion chamber 7 is opened when the crank angle during the exhaust stroke is about 30 ° BTDC and closed when the crank angle before the BDC is about 165 ° ATDC. Is completed before the end of the intake stroke.
Thus, the supply of the sub chamber fuel gas is completed by supplying the sub chamber fuel gas to the sub combustion chamber 7 and setting the completion of the supply to the time when the piston descends during the intake stroke. The ignition plug at the end of the compression stroke can be used for a long time until the fuel for the sub chamber is ignited, and the lean mixture flowing from the injection hole 10 into the sub combustion chamber 7 is sufficient until the ignition timing. The subchamber fuel can be mixed.
[0021]
Further, in the sub-chamber combustion type engine in which the crank chamber angle before the BDC at the time of the intake stroke is set to a time of about 165 ° ATDC as in this method, the supply of the sub-chamber fuel gas is supplied. When the supply pressure of the sub-chamber fuel gas is changed in the sub-chamber combustion engine in which the completion of the supply of the sub-chamber fuel gas is set to the time after the BDC as in the prior art, when the pressure is changed The thermal efficiency is shown in FIG.
As can be seen from FIG. 4, in this method, even if the supply pressure of the fuel gas for the sub chamber is changed, high thermal efficiency can be maintained. When closed, the overall heat exchange rate is low, and if the supply pressure of the sub chamber fuel gas is set higher, the heat exchange rate is further deteriorated. This is because in the conventional sub-chamber combustion engine, the sub-chamber fuel gas is supplied halfway through the compression stroke, so the mixing time until ignition is short and the combustion in the sub-combustion chamber 7 is unstable. It can be said.
[0022]
[Another embodiment]
In the cam mechanism portion A of the above embodiment, the intake valve 5 and the sub chamber valve 13 are configured to be driven by separate cams. However, both valves can be driven by the same cam. .
That is, as shown in FIG. 5, the camshaft 24 that rotates once per cycle by the rotational movement of the crankshaft, the two cams 32 and 22 provided on the camshaft 24, and the surfaces of the cams 32 and 22 respectively. Two push rods 33 and 26 that reciprocate in the axial direction according to the shape, a rocker arm 34 that swings around the rocker arm shaft 31 by the push rod 33 and opens and closes both the intake valve 5 and the sub chamber valve 13, and a push rod 26. An exhaust rocker arm 29 that swings around the rocker arm shaft 31 to open and close the exhaust valve 6 is provided.
[0023]
Further, in this method, the sub chamber valve 13 is configured to be closed when the piston is lowered during the intake stroke, so that the intake valve 5 is also closed when the piston is lowered during the intake stroke. As a result, the sub-chamber combustion engine can be operated in a so-called Miller cycle system, and the efficiency can be further improved with a simple configuration.
[0024]
Moreover, as a gaseous fuel which can be used for the subchamber combustion type engine of this invention, arbitrary hydrocarbon gas fuels, such as propane and hydrogen other than city gas, can be used.
[0025]
【The invention's effect】
With this method, in the sub-chamber combustion type engine, even if the supply pressure of the sub-chamber fuel is set high, the supply amount does not become excessive, and the sub-chamber fuel is mixed well in the sub-combustion chamber. Can be. For this reason, the efficiency of the engine can be greatly improved, variation in the amount of fuel supplied to the sub chamber can be suppressed, and stable operation can be maintained over a long period of time.
[Brief description of the drawings]
1 is a cross-sectional view of a main part showing a combustion chamber and a fuel supply system of a sub-chamber combustion type engine. FIG. 2 is a perspective view of a cam mechanism portion A of the sub-chamber combustion type engine shown in FIG. FIG. 4 is a graph showing a change in the lift amount of FIG. 13. FIG. 4 is a graph showing a change in thermal efficiency when the supply pressure of the fuel gas for the sub chamber is changed in the sub chamber combustion type engine. The perspective view which shows another structure of the cam mechanism part A of this invention
DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Main combustion chamber 3 Piston 4 Cylinder 5 Intake valve 6 Exhaust valve 7 Subcombustion chamber 10 Injection hole 13 Subchamber valve 14 Spark plug 32 Cam A Cam mechanism part

Claims (2)

The sub-chamber fuel is supplied to the sub-combustion chamber provided in the cylinder head, and the sub-chamber fuel supplied to the sub-combustion chamber is ignited by a spark plug, and the main chamber fuel is supplied to the main combustion chamber via a plurality of nozzle holes. A method of operating a sub-chamber combustion type engine that jets a flame torch into a combustion chamber,
A sub-chamber combustion engine operating method in which the sub-chamber fuel is supplied to the sub-combustion chamber, and the supply of the sub-chamber fuel to the sub-combustion chamber is completed at a time when the piston is descending during the intake stroke. The sub-chamber combustion according to claim 1, wherein the sub-chamber valve for supplying the sub-chamber fuel to the sub-combustion chamber is opened / closed by a cam that opens and closes the intake valve and sets the closing timing to the time when the piston descends during the intake stroke. How to operate the engine.

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