JP5316449B2 - Combustion chamber structure of internal combustion engine - Google Patents

Description

  The present invention relates to a combustion chamber structure that avoids a knocking phenomenon in a combustion chamber of an internal combustion engine.

In order to improve the theoretical thermal efficiency of internal combustion engines, especially gasoline, a method with a high compression ratio is being implemented.
However, in the combustion chamber of a gasoline engine, the premixed gas ignited by the spark plug propagates to the piston side and the cylinder side, so that both the high-temperature combustion gas and the unburned gas at the outer periphery are in the combustion chamber. Coexist.
In particular, in the case of a high compression ratio, the unburned gas around the combustion chamber becomes high temperature and pressure due to the combustion heat of the gas burned by the spark plug and compression due to the expansion of the combustion gas, exceeding the autoignition temperature and causing explosive combustion (knocking) Wake up.

Other causes of knocking include when the internal combustion engine is continuously subjected to high load conditions and the temperature in the combustion chamber increases, deposits (carbon lumps) adhering to the combustion chamber serve as the ignition source, or ignition timing. The case where it is controlled in the direction of the travel is known.
Therefore, it is known that knocking can be avoided in the gasoline engine by delaying the ignition timing.

FIG. 4 shows the relationship between the pressure in the combustion chamber and the angle of the crankshaft according to the ignition timing during operation of a general internal combustion engine, and shows that the maximum pressure in the combustion chamber decreases when the ignition timing is delayed. Yes.
If the normal ignition timing is about 20 ° BTDC (before the top dead center), the maximum pressure is generated when the piston slightly exceeds the top dead center of the piston. (Solid line A in FIG. 4)
When the ignition timing is retarded (retarded) to BTDC 10 °, the maximum pressure in the combustion chamber decreases as indicated by the thin broken line B in FIG. This is because the volume of the combustion chamber is increasing because the piston starts to descend beyond the top dead center when the combustion gas in the combustion chamber reaches the maximum pressure by delaying the ignition timing. .
Similarly, when the ignition timing is further retarded to BTDC 5 °, the maximum pressure in the combustion chamber further decreases as shown by the broken line C in FIG.
Therefore, if the ignition timing is delayed, the generated pressure in the combustion chamber is lowered and the output is reduced.

FIG. 5 shows the relationship between the compression ratio and the partial load fuel consumption, and shows that the partial load fuel consumption improves as the compression ratio increases. This is because the combustion pressure in the combustion chamber increases and the piston pressing force increases.
Therefore, knocking is likely to occur when increasing the output of the internal combustion engine and saving fuel.
Further, as shown in FIG. 6, the curve D indicates the knocking generation timing (knocking ignition timing) of the full load with respect to the pressure of the combustion gas in the combustion chamber. This shows that the knocking occurrence time tends to be retarded as the compression ratio increases.
Therefore, when the compression ratio is increased, the compression pressure of the combustion chamber increases and the combustion chamber temperature increases, so that knocking is likely to occur. Therefore, it is necessary to delay the ignition timing as described above.
On the other hand, curve E shows the generated torque characteristics at low speed and full load. When the ignition timing is delayed, the maximum pressure in the cylinder decreases as described above with reference to FIG. 4, and the output as the internal combustion engine decreases. Have a problem.
JP-A-2006-336519 (Patent Document 1) is disclosed as a prior art for avoiding knocking.

According to Japanese Patent Laid-Open No. 2006-336519, when a piston is at the top dead center position, a catalyst (base metal oxidation catalyst) that performs oxidation activity in a temperature range where knocking occurs at a position farthest from the spark plug is disposed. Te, made to perform a slow combustion by catalytic combustion before the temperature of the premixed gas becomes self-ignition temperature, Ru der as to prevent explosive self ignite (knocking).

JP 2006-336519 A

According to the technology of the prior art document, since the end gas in the end gas section is in a state of oxygen deficiency and the slow combustion is performed, the pressure rise is slow, the maximum pressure in the combustion chamber is lowered, and the output performance is sacrificed. There is .
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an internal combustion engine that suppresses self-ignition (knocking) while increasing the compression ratio in the combustion chamber of the internal combustion engine, thereby improving output and improving fuel consumption. To do.

The present invention achieves such an object, and includes a cylinder disposed in a cylinder block of an internal combustion engine, a piston that slides inside the cylinder, a combustion chamber that is opposed to the top of the piston, and the cylinder. A cylinder head attached to the block; an intake port formed in the cylinder head and communicating with the combustion chamber; an intake valve for opening and closing the intake port with respect to the combustion chamber; and an exhaust port communicating with the combustion chamber; An exhaust valve that opens and closes the exhaust port with respect to the combustion chamber, and a spark plug disposed in a central portion of the combustion chamber, and a premixed gas in which fuel and intake air are premixed is sucked into the combustion chamber, in the combustion chamber structure for an internal combustion engine to be burned by the spark plug, when the compression of intake air by the premixed gas from the inlet port in a circumferential portion near the combustion chamber Occluding the oxygen, forming on said at combustion of premixed gas is disposed an oxygen storage member to release oxygen, the oxygen storage member strip circular shaped outer peripheral portion facing the portion of the piston of the cylinder head It is characterized by being arranged .

  In such an invention, a so-called end gas portion located around the combustion chamber sucks the oxygen of the premixed gas mixed with fuel during the compression stroke of the piston by the oxygen storage member, and stores the oxygen in the portion during the compression stroke. In addition to preventing the occurrence of abnormal combustion in an oxygen-deficient state, oxygen is deficient due to combustion during combustion by the spark plug, so that oxygen is released from the oxygen storage member to promote combustion of the premixed gas, and the internal combustion engine Has the effect of deriving high output.

Further, in the present invention, the oxygen storage member is formed in a belt-like circular shape at the portion facing the outer peripheral portion of the piston of the cylinder head, so that the cylinder is formed by the deposit (carbon block) attached to the end portion of the combustion chamber. It has the effect of preventing the end gas in the inner peripheral portion from self-igniting and deriving a high output of the internal combustion engine.

In the present invention, preferably, in addition to the above configuration, the oxygen storage member may be disposed on an outer peripheral portion of a portion of the piston top surface facing the exhaust port.

  By adopting such a configuration, the exhaust port side has less cooling effect due to intake air than the intake port side, and because it takes a long time to be exposed to exhaust gas, the temperature tends to rise, so the end gas is likely to ignite spontaneously. Only a high-priced oxygen storage member is provided to suppress an increase in cost.

In the present invention, preferably, in addition to the above configuration, the oxygen storage member may be disposed on the outer peripheral edge of the exhaust port of the cylinder head.

  By adopting such a configuration, since the exhaust gas at the periphery of the exhaust port passes high-temperature exhaust gas, it tends to be particularly high in temperature.Therefore, an expensive oxygen storage member is disposed only in the portion where the end gas is likely to ignite, It has the effect of suppressing an increase in cost.

  According to the present invention, it is possible to achieve high output and fuel saving of an internal combustion engine by disposing an oxygen storage member in the end gas portion of the combustion chamber and preventing occurrence of knocking even when the compression rate in the combustion chamber is increased. Has an effect.

These show the schematic explanatory drawing of the combustion chamber concerning this invention. BRIEF DESCRIPTION OF THE DRAWINGS (A) is explanatory drawing of the upper direction from the combustion chamber side which arrange | positioned the oxygen storage member in the position facing the piston outer peripheral part of the cylinder head concerning 1st Embodiment, (B) ) Shows a top view explanatory view from the combustion chamber side in which an oxygen storage member is disposed on the outer peripheral portion of the exhaust port of the cylinder head according to the second embodiment. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of the present invention, (A) is an explanatory view of a piston-like surface view in which an oxygen storage member is arranged on the outer periphery of a piston according to a third embodiment, and (B) is a piston according to a fourth embodiment. The explanatory view of the piston-like surface view in which the oxygen storage member is disposed on the side of the outer peripheral portion facing the exhaust port is shown. Shows the relationship between the ignition timing and the maximum pressure in the combustion chamber. Indicates the characteristics of partial load fuel consumption with respect to the compression ratio. Shows the relationship between the occurrence of knocking and the torque with respect to the compression ratio.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to specific examples unless otherwise specifically described. Only.

(First embodiment)
As shown in FIG. 1, an internal combustion engine 1 which is an internal combustion engine includes a cylinder 6 disposed in a cylinder block 3, and a piston 2 disposed in the cylinder 6 so as to be slidable along the axial direction of the cylinder 6. A combustion chamber 5 having a surface opposed to the top surface 21 of the piston 2 and surrounded by a cylinder head 4 attached to the cylinder block 3 via a gasket 31 is formed.
In order to maintain confidentiality between the piston 2 and the cylinder 6, a piston ring 23 is fitted in a ring groove disposed on the outer periphery of the upper portion of the piston 2.
When the premixed intake air is sucked into the combustion chamber 3 and compressed by the piston 2, it is burned by the spark plug 7, and the output of the internal combustion engine 1 is output from the crankshaft (not shown) through the connecting rod 8. ing.

A so-called premixed gas in which fuel and intake air are mixed in advance is pressurized by a supercharger or the like, passes through an intake valve 44 having an intake port 42 opened, and is sucked into the combustion chamber 5. The sucked premixed gas is compressed by the piston 2 and becomes high temperature and pressure.
FIG. 2 (A) shows a top view of the cylinder head 4 from the combustion chamber 5, and an oxygen occlusion formed in a belt-like circular shape at a portion facing the outer periphery of the piston 2 of the cylinder head 4 facing the combustion chamber 5. A member is disposed. As this oxygen storage member, for example, rare earth oxysulfate 45 (Ln2O2So4) is disposed.
Rare earth oxysulfate Ln2O2SO4 is reduced to Ln2O2SO (oxygen release) by H2 (hydrogen), CO (carbon monoxide), C3H6 (propylene), etc., reversibly reoxidized by O2 (oxygen), etc. Ln2O2SO4 (oxygen storage) ) Moreover, the reduction / reoxidation reaction is fast and proceeds even at low temperatures. (For Ln2O2SO4, according to a report from NEDO (New Energy and Industrial Technology Development Organization))

The so-called end gas located in the outer peripheral portion (end portion) of the premixed gas compressed in the combustion chamber 5 is occluded in the rare earth oxysulfate Ln2O2SO4, and the premixed gas becomes oxygen-deficient.
When the piston 2 rises and the premixed gas compressed by the spark plug 7 ignites, the flame rapidly propagates to the end gas portion. The heat of the flame makes the end gas hot and high pressure, but the premixed gas cannot self-ignite because it is in an oxygen-deficient state even at the auto-ignition temperature.
When the flame propagation in the combustion chamber reaches the end gas part, the combustion gas contains a large amount of CO (carbon monoxide), so the rare earth oxysulfate Ln2O2SO4 is reduced to Ln2O2SO, and O2 (oxygen) is released rapidly. End gas burns.
Thereby, even if the premixed gas pressure is increased, it is possible to prevent the occurrence of self-ignition (knocking) in the end gas portion, and to achieve high output and fuel saving of the internal combustion engine.
Moreover, even if a fire such as a carbon lump exists in the end gas part, the pre-combustion gas is in an oxygen-deficient state, so that explosive combustion can be prevented.

(Second Embodiment)
This embodiment combines the arrangement | positioning location of an oxygen storage member with respect to 1st Embodiment.
Therefore, the description of the same part is omitted, and the same reference numerals are used for the same parts in the description. This will be described with reference to FIG.
FIG. 2 (B) shows the cylinder head 45 as viewed from the piston 2 side. A belt-like rare earth oxysulfate 46 is formed on the outer circumferential edge of the exhaust port 43 of the cylinder head 45 on the semicircular portion opposite to the intake valve 44. Is arranged.

Rare earth oxysulfate, which is a band-like oxygen storage member only in the portion where carbon masses or the like are easily attached because the burned high-temperature exhaust gas passes, and the portion exposed to the exhaust gas is likely to become high temperature. 46 is arranged to reduce the cost.
Since the flame propagation by the spark plug 7 is transmitted quickly to the portion close to the spark plug 7, it is difficult for self-ignition (knocking) to occur.

(Third embodiment)
This embodiment is a combination of the oxygen storage member on the piston 21 side with respect to the first embodiment. This will be described with reference to FIG.
FIG. 3A shows a top view of the piston 24, and a rare earth oxysulfate 47 is disposed on the entire outer periphery of the top surface of the piston 24.
The effect of this embodiment is that, in addition to the first embodiment described, the piston 24 is generally made of aluminum die-cast, so that the manufacturing equipment is simpler than the cast cylinder head 4, and the oxygen storage member 47. This has the effect of reducing the cost of equipment change for disposing the equipment.

(Fourth embodiment)
FIG. 3 (B) shows a top view of the piston 25. A band-like oxysulfate 47 is combined and disposed on the exhaust valve 43 side half periphery of the outer periphery of the piston 24 top surface as compared with the first embodiment . .
This is because when the premixed gas is introduced into the combustion chamber 5 from the intake port 42 during the intake stroke of the piston 25 (the piston 25 is in the vicinity of the top dead center), the intake port 42 side of the piston 25 is particularly premixed gas. Therefore, the self-ignition is unlikely to occur. Therefore, in order to reduce the cost, the exhaust valve 43 has a half circumference.

According to each of the above embodiments, the flame of the premixed gas ignited by the spark plug 7 quickly propagates to the end gas portion, and the heat of the flame makes the end gas high temperature and high pressure. There is no self-ignition.
Since the rare earth oxysulfate Ln2O2SO4 is reduced by CO (carbon monoxide) in the flame-propagating combustion gas and becomes Ln2O2SO and O2 (oxygen) is released rapidly, the end gas burns, so the premixed gas pressure is increased. However, it has the effect of preventing the occurrence of self-ignition (knocking) in the end gas section and achieving high output and fuel saving of the internal combustion engine.
In addition, although the arrangement | positioning site | part of the rare earth oxysulfate Ln2O2SO4 which is this oxygen storage member was demonstrated separately, it is easy to use together combining each suitably.

  It can be applied to an internal combustion engine that achieves both high output and fuel saving by increasing the compression pressure in the combustion chamber.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Piston 3 Cylinder block 4 Cylinder head 5 Combustion chamber 6 Cylinder 7 Spark plug 21 Top surface 24 Piston 25 Piston 41 Exhaust port 42 Intake port 43 Exhaust valve 44 Intake valve 45 Oxysulfate A
46 Oxysulfate B
47 Oxysulfate C
48 Oxysulfate D

Claims (3)

A cylinder disposed in a cylinder block of an internal combustion engine; a piston that slides inside the cylinder; a cylinder head that forms a combustion chamber facing the top of the piston and is attached to the cylinder block; and the cylinder An intake port that is formed in the head and communicates with the combustion chamber, an intake valve that opens and closes the intake port with respect to the combustion chamber, an exhaust port that communicates with the combustion chamber, and opens and closes the exhaust port with respect to the combustion chamber Combustion of an internal combustion engine comprising an exhaust valve and an ignition plug disposed in a central portion of the combustion chamber, wherein a premixed gas in which fuel and intake air are premixed is sucked into the combustion chamber and burned by the ignition plug In the room structure,
An oxygen storage member is disposed near the circumference of the combustion chamber to store oxygen when the premixed gas sucked from the intake port is compressed, and to release oxygen when the premixed gas is burned ,
The combustion chamber structure of an internal combustion engine, wherein the oxygen storage member is formed in a belt-like circular shape at a portion of the cylinder head facing the outer peripheral portion of the piston . The combustion chamber structure for an internal combustion engine according to claim 1, wherein the oxygen storage member is disposed on an outer peripheral portion of a portion of the piston top surface facing the exhaust port . 2. The combustion chamber structure of an internal combustion engine according to claim 1, wherein the oxygen storage member is disposed at an outer peripheral edge portion of the exhaust port of the cylinder head .

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