JP2010065673A - Multistage compression self-ignition internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To expand the operation output band of a compression self-ignition internal combustion engine and facilitate change over to other operation modes. <P>SOLUTION: In a four-cycle compression self-ignition internal combustion engine using gasoline as fuel, an auxiliary chamber 103 is provided and a communication part to a main combustion chamber 106 is partitioned by a communication valve 105. A spark plug 104 and an intake valve for supplying air fuel mixture are provided in the auxiliary chamber. The communication valve is opened in an intake process, an intake valve 102 of the auxiliary chamber is opened at a later half of the process, rich air fuel mixture for plug ignition is supplied to the auxiliary chamber, and the communication valve is closed near CA corresponding to compression ratio 9. Compression further progresses in the main combustion chamber and front flame reaction starts. However, compression ratio is set to pressure before self ignition. Ignition is done by the spark plug of the auxiliary chamber near a top dead center. When pressure of the auxiliary chamber exceeds pressure of the main combustion chamber, the communication valve is opened, gas after combustion flows in the main combustion chamber, and air fuel mixture in the main combustion chamber is compressed again. Since front flame reaction progresses, ignition occurs in a short period of time and pressure rises, and the communication valve is closed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ignition control method and an operation method of a premixed compression self-ignition internal combustion engine.

  Currently, there are EGR for circulating an appropriate amount of exhaust gas in an ECU, a plasma jet for injecting plasma into a combustion chamber, and a pulse jet method. Further, as described in the following application by the inventor, there is a method in which after-combustion gas ignited by a spark plug in a low compression ratio cylinder having a different rotational phase is released to a combustion chamber and compressed and ignited to a premixed gas compressed to the point before the ignition point It is shown.

Japanese Patent Application No. 2006-111596

  At present, premixed compression self-ignition (HCCI) internal combustion engines that are self-ignited by compression due to compression are attracting attention because they are currently energy efficient and clean. However, because the ignition conditions change due to load fluctuations and changes in operating conditions such as the number of revolutions, it is difficult to reliably ignite, and since the power output band is narrow, plug ignition or It is necessary to use together with the diesel ignition system. However, since the compression ratio optimum for the operation of HCCI and the compression ratio in other ignition systems are different, switching of operation is difficult.

  In the HCCI ignition method, the EGR method, which is currently mainstream, controls the exhaust gas recirculation amount in the next cycle by a pressure and temperature sensor and a microcomputer. However, this method is difficult to cope with a sudden change in output and rotation speed, and the energy saving effect is not so high as expected because the output band is particularly narrow. Furthermore, even in the ignition trigger method by heat or chemical change such as plasma jet or pulse jet, the output band is somewhat widened, but the problem at the time of operation mode switching remains unsolved. Further, in the above-mentioned patent document, when the air-fuel mixture ignited by the spark plug moves to the combustion chamber of the HCCI cylinder, and when the gas of the HCCI cylinder after ignition flows back to the ignition plug side cylinder, the friction with the communication port surface Pressure loss occurs. Therefore, in this method, a method for reducing the pressure loss is required.

  In operation mode switching, a gasoline engine is used to switch to the plug ignition mode by providing a negative overlap period by valve control and allowing exhaust to remain in the cylinder to enable self-ignition at a low compression ratio. Can be realized without changing the mechanical compression ratio, but the efficiency is not so high in this method because the compression ratio can be kept low. Therefore, there is a need for a further expansion of the operable output band of the HCCI mode, a more reliable ignition method, and a simpler and more reliable switching method without reducing the efficiency.

  In the compression ignition internal combustion engine, the first means is a combustion chamber having a compression ratio near the compression auto-ignition pressure, but a compression ratio less than the compression auto-ignition pressure, and communicates with the combustion chamber to other multistage compression means. The multi-stage compression means reduces the volume of the combustion chamber when the cylinder is near the top dead center, and the mixture is compressed and ignited.

  The second means is an internal combustion engine that is operated by switching between a compression ignition mode and a plug ignition mode that is ignited by a spark plug during operation, but in the compression ignition mode, the compression ratio is close to the compression auto-ignition pressure. When the piston position of the main cylinder set to a compression ratio lower than the self-ignition pressure is near top dead center, it is a multistage compression ignition engine that is compressed again by means other than the piston and ignited. The volume of the combustion chamber can be changed to a compression ratio necessary for the compression ignition operation and a volume corresponding to the compression ratio necessary for the plug ignition mode.

  The third means is an internal combustion engine that is operated by switching between a compression ignition mode for compressing and igniting a relatively uniform air-fuel mixture and a diesel ignition mode for injecting and igniting fuel during high pressure during operation. In the ignition mode, the compression ratio is close to the compression auto-ignition pressure, but when the piston position of the main cylinder set to a compression ratio lower than the self-ignition pressure is near top dead center, it is compressed again by means other than the piston. The multi-stage compression ignition engine to be ignited, and the multi-stage compression means makes it possible to change the volume of the combustion chamber of the main cylinder to a compression ratio required for the compression ignition operation and a volume corresponding to the compression ratio required for the diesel ignition mode. It is characterized by that.

  The fourth means is characterized in that the multistage compression means is constituted by another cylinder communicating with the combustion chamber of the cylinder.

  A fifth means is that the multi-stage compression means is provided with a sub-combustion chamber in the combustion chamber of the cylinder, a valve is provided at the boundary between the ignition means and the combustion chamber in the sub-combustion chamber, and in the compression auto-ignition mode, the sub-combustion chamber is provided. In this case, the combustion is independently performed, the valve is opened, the air-fuel mixture in the main combustion chamber is compressed and ignited with the gas after combustion, and the compression ratio is changed by opening and closing the valve when the operation mode is switched.

  Sixth means, the first stage multistage compression means, provided a sub-combustion chamber in the combustion chamber of the compression self-loading cylinder, provided a spark plug in the sub-combustion chamber, provided a valve at the boundary between the main combustion chamber and the sub-combustion chamber, When compression is performed to the compression ratio suitable for the plug ignition mode in the middle of the compression process, the valve is closed and the auxiliary combustion chamber is ignited by the ignition plug, so that the pressure in the auxiliary combustion chamber is higher than the pressure in the main combustion chamber. At that time, the valve is opened, and the air-fuel mixture in the main combustion chamber is compressed and ignited with the post-combustion gas, and when switching to the plug ignition mode, the valve is opened to reduce the compression ratio.

  The seventh means is characterized in that the compression ratio in the vicinity of the compression auto-ignition pressure is equal to or higher than the pressure at which the pre-flame reaction that causes the fuel component to decompose and oxidize when the temperature rises.

  In the conventional HCCI engine, since the maximum point of pressure due to compression before ignition is near top dead center, it is difficult to perform a large ignition delay, and it corresponds to a heavy mixture at high load or a relatively dense mixture It was difficult. For the same reason, it has been difficult to ignite with a low-concentration gas mixture. In the present invention, since recompression can be performed at an arbitrary time, compression after top dead center is also possible, so that a large retardation can be achieved, and the operating range to the rich side of the air-fuel ratio can be greatly expanded. Furthermore, since the effective compression ratio can be freely changed, a low-concentration air-fuel mixture can be self-ignited with a high effective compression ratio. Furthermore, since the compression ratio of another operation mode can be changed by using the space volume of the multistage compression means provided in communication with the combustion chamber, it is possible to switch the operation mode with a plurality of compression ratios. Easy to do.

  In the present invention, a four-cycle internal combustion engine capable of self-igniting by recompressing an air-fuel mixture mixed relatively uniformly by multistage compression at an arbitrary timing with a relatively wide adjustment pressure range will be described in the following embodiments. To do.

  This example shows an example of the present invention. FIG. 1 is a side sectional view for explaining an example of the present invention. 101 is a cylinder head, 102 is a sub-combustion chamber intake valve, 103 is a sub-combustion chamber, 104 is a spark plug, 105 is a communication valve, 106 is a main combustion chamber, and 107 is a piston.

  The present embodiment is an automobile multi-cylinder engine that can switch between HCCI using gasoline as fuel and plug ignition operation. The cylinder head (101) is provided with a sub-combustion chamber (103), and the sub-combustion chamber (103) and the main combustion chamber (106) are partitioned by a communication valve (105) so as to be able to communicate / close. The cylinder head (101) is provided with an intake valve (not shown) and an exhaust valve (not shown) for the main combustion chamber, and an electronic fuel injection device (not shown) for injecting fuel into the intake port of each cylinder. Z). The auxiliary combustion chamber (103) is provided with an ignition plug (104) and an auxiliary combustion chamber intake port (102).

  During the intake process, the intake valve (not shown) and the communication valve (105) in the main combustion chamber are opened. The intake valve (102) for the auxiliary combustion chamber is opened for a period of time during which the air-fuel mixture necessary for filling the auxiliary chamber (103) can be secured during the period until the piston (107) reaches bottom dead center during the intake stroke. A rich air-fuel mixture mixed separately for the auxiliary combustion chamber is supplied to the auxiliary chamber intake port (102). In the compression process, the piston (107) rises, and when the compression ratio is around 9, the communication valve (105) is closed and isolated from the main combustion chamber (106). The piston (107) is further raised, and the main combustion chamber (106) is compressed to 90% of the self-ignition compression ratio position. In normal compression auto-ignition, the fuel undergoes a chemical change due to an increase in the temperature of adiabatic compression, and the decomposition and oxidation reaction (pre-flame reaction) proceeds to form a cool flame, and then a hot flame is formed, leading to ignition. In the example, since the compression ratio is set so as not to lead to self-ignition, a chemical change of the pre-flame reaction occurs, but it does not lead to formation of a hot flame as it is. The air-fuel mixture in the main combustion chamber (106) is ready for ignition by the pre-flame reaction, and the sub-chamber air-fuel mixture is ignited by the ignition plug (104) in the sub-chamber (103) near the top dead center. When the pressure in the auxiliary combustion chamber (103) rises due to flame propagation and becomes larger than the compressed air-fuel mixture pressure in the compressed main combustion chamber (106), the communication valve (105) opens and the auxiliary combustion chamber (103) The after-combustion gas flows into the main combustion chamber (106), compresses the air-fuel mixture in which the pre-flame reaction is proceeding in the main combustion chamber (106), and ignites in a short time because it exceeds the self-ignition temperature. After ignition, since the pressure in the main combustion chamber (106) exceeds the pressure in the sub-combustion chamber (103), the communication valve (105) is closed to minimize the pressure loss in the main combustion chamber (106). . In the exhaust process, the communication valve (105) is opened to exhaust from the exhaust port of the main combustion chamber (106). The compression ignition can be controlled by changing the ignition timing of the ignition plug (104), the mixture concentration, and the timing of opening the communication valve. In a low load and large air-fuel ratio region, it is possible to expand the operation output region downward by increasing the fuel concentration in the sub-combustion chamber (103) and increasing the pressure during two-stage compression. Furthermore, the plug ignition timing in the sub-combustion chamber can be extended to the high output side by retarding.

  Further, on the rich side from near the stoichiometric state, the communication valve (105) is always opened, so that the combustion chamber volume including the auxiliary combustion chamber (103) volume is obtained, the compression ratio is reduced, and the flame is propagated by the spark plug. Combustion is possible.

  This example shows an example of the present invention. FIG. 2 is a top cross-sectional view for explaining an example of the present invention. 201 is a combustion chamber, 202 is an engine cylinder, 203 is a communication window, 204 is a pressure-reducing cylinder, 205 is a pressure-reducing piston, and 206 is an arrow indicating a sliding direction.

  The present embodiment is an automobile multi-cylinder engine that can switch between HCCI using gasoline as fuel and plug ignition operation. FIG. 2 is a cross-sectional view of the cylinder as viewed from above and cut across the combustion chamber. The cylinder (202) is provided with a pressure-reducing cylinder (204) for multistage compression so as to communicate with the combustion chamber (201). The pressure increasing / decreasing cylinder (204) is provided with a communication window (203) and communicates with the combustion chamber (201). The two cylinders (202, 204) have a volume relationship such that the pressure-reducing piston (205) is 95% of the self-ignition compression ratio position at the 50% position of the communication window (203). When the engine / cylinder (202) is near the top dead center, the pressure-reducing piston (205) is a hydraulic device (not shown) composed of a high-pressure hydraulic pump (not shown) and a common rail (not shown). (Not shown) and compressed into the combustion chamber (201). The combustion chamber volume is reduced and the ignition exceeds the auto-ignition pressure. Ignition control is possible by adjusting the push-in timing and push-in amount, and if the variable volume ratio can be increased, the self-ignition operation output band can be expanded. Further, when used in combination with the spark plug ignition mode, the compression ratio can be lowered by operating the pressurizing and depressurizing piston (205) in the fully pulled out state, and the operation mode can be switched. When used in combination with the diesel mode, operation at a higher compression ratio is possible by operating with the pressurizing and depressurizing piston (205) fully depressed.

  This example shows an example of the present invention. FIG. 3 is a perspective explanatory view for explaining an example of the present invention. Reference numeral 301 denotes a communication opening, 302 denotes an HCCI cylinder, 303 denotes an HCCI piston, 304 denotes an SI cylinder, and 305 denotes an SI piston.

  The present embodiment is an automobile multi-cylinder engine that can switch between HCCI using gasoline as fuel and plug ignition operation. The HCCI cylinder (302) is connected with a small ignition engine, the SI cylinder (304), through the communication opening (301) to the combustion chamber of the HCCI cylinder. The SI cylinder (304) is provided with an intake valve (not shown), an exhaust valve (not shown), and a spark plug (not shown), and the SI piston (305) communicates at a crank angle ATDC of 30 degrees during the expansion stroke. An opening (301) is provided. The compression ratio of the HCCI cylinder (302) before communication is a compression ratio that is 80% of the compression auto-ignition compression ratio. The volume ratio of both cylinders (302, 304) is 20 to 1, and the SI piston (305) is transmitted biaxially using a shaft different from HCCI, and is used for wheel driving. The SI cylinder (304) is supplied with an air-fuel mixture compressed at a compression ratio similar to the concentration suitable for plug ignition from the intake valve, and the HCCI piston (303) is located near the top dead center. (304) is ignited by the spark plug, and the SI piston (305) flows into the combustion chamber of the HCCI cylinder (302) through the communication opening (301) at 30 degrees CA to secondarily compress the air-fuel mixture, and the ignition temperature is reduced. Ignite beyond.

  Premixing in the HCCI cylinder (303) by adjusting the concentration and amount of the air-fuel mixture supplied to the cylinder (304) of the ignition plug ignition engine and the ignition timing at the ignition plug of the cylinder to make the air-fuel mixture rich Ignition is easy even if I'm sparse. Further, by retarding the plug ignition timing, knocking can be avoided even in a rich mixture on the HCCI side, and the operable range can be expanded. By reducing the compression ratio as much as possible and increasing the difference from the auto-ignition pressure within a range equal to or higher than the pre-flame reaction occurrence pressure, the HCCI operation range can be expanded. However, if the output on the SI cylinder (304) side is increased too much, the amount of movement of the internal gas increases and the pressure loss increases. Therefore, by reducing the cylinder (304) volume of the ignition plug ignition engine to 1/20 of that of the HCCI cylinder, the movement of the internal gas is minimized and the pressure loss caused by friction with the communication wall is reduced. can do.

  Compression self-ignition internal combustion engine. It is used for engines such as gasoline, diesel, gas, alcohol, ether and other biofuels for power for automobiles, ships, and power generation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view for explaining an internal combustion engine of a first embodiment as an example of the present invention. FIG. 6 is a top cross-sectional view for explaining an internal combustion engine according to a second embodiment as an example of the present invention. FIG. 5 is a perspective explanatory view for explaining an internal combustion engine of a third embodiment as an example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Cylinder head 102 Subcombustion chamber intake valve 103 Subcombustion chamber 104 Spark plug 105 Communication valve 106 Main combustion chamber 107 Piston 201 Combustion chamber 202 Engine cylinder 203 Communication window 204 Pressurization cylinder 205 Pressurization piston 206 Arrow which shows sliding direction 301 Communication opening 302 HCCI cylinder 303 HCCI piston 304 SI cylinder 305 SI piston

Claims (7)

  In a compression ignition internal combustion engine, it is a combustion chamber having a compression ratio near the compression autoignition pressure, but less than the compression autoignition pressure, and another multistage compression means is provided in communication with the combustion chamber so that the cylinder is An internal combustion engine capable of multistage compression self-ignition characterized by reducing the volume of a combustion chamber with the multistage compression means when in the vicinity of a dead center and causing the mixture to undergo compression autoignition.   In an internal combustion engine that is operated by switching between a compression ignition mode and a plug ignition mode that is ignited by a spark plug during operation, in the compression ignition mode, the compression ratio is close to the compression ignition pressure, but lower than the ignition pressure. When the piston position of the main cylinder set to the compression ratio is near top dead center, it is a multistage compression ignition engine that is compressed again by means other than the piston and ignited, and the volume of the combustion chamber of the main cylinder is reduced by the multistage compression means. An internal combustion engine capable of multi-stage compression ignition, wherein the compression ratio required for the compression ignition operation and the volume corresponding to the compression ratio required for the plug ignition mode can be changed.   In an internal combustion engine operated by switching between a compression ignition mode for compressing and igniting a relatively uniform air-fuel mixture and a diesel ignition mode for injecting and igniting fuel during high pressure during operation, Although the compression ratio is close to the ignition pressure, when the main cylinder piston position set to a compression ratio lower than the self-ignition pressure is near top dead center, compression is performed again by means other than the piston and ignition is performed. A multistage engine characterized in that the multistage compression means can change the volume of the combustion chamber of the main cylinder to a compression ratio necessary for compression auto-ignition operation and a volume corresponding to the compression ratio necessary for the diesel ignition mode. An internal combustion engine capable of compression ignition.   The internal combustion engine capable of multi-stage compression ignition according to claim 1, wherein the multi-stage compression means is constituted by another cylinder communicating with a combustion chamber of the cylinder.   The multi-stage compression means is provided with a sub-combustion chamber in the combustion chamber of the cylinder, a valve is provided at the boundary between the ignition means and the combustion chamber in the sub-combustion chamber, and in the self-combustion mode, it is burned independently in the sub-combustion chamber, 4. The multistage compression ignition according to claim 2, wherein the gas mixture in the main combustion chamber is compressed and ignited with the gas after combustion, and the compression ratio is changed by opening and closing the valve when the operation mode is switched. Possible internal combustion engine.   The first-stage multi-stage compression means is provided with a secondary combustion chamber in the combustion chamber of the compression self-loading cylinder, an ignition plug is provided in the secondary combustion chamber, a valve is provided at the boundary between the main combustion chamber and the secondary combustion chamber, and plug ignition is performed during the compression process. When the compression ratio is suitable for the mode, the valve is closed, the auxiliary combustion chamber is ignited with a spark plug, and the valve is opened when the pressure in the auxiliary combustion chamber becomes higher than the pressure in the main combustion chamber. 3. The multistage compression ignition according to claim 2, wherein the air-fuel mixture in the main combustion chamber is compressed and ignited with the post-combustion gas, and the compression ratio is reduced by opening the valve when switching to the plug ignition mode. Internal combustion engine.   The compression ratio in the vicinity of the compression auto-ignition pressure is a compression ratio corresponding to a pressure higher than a pressure at which a pre-flame reaction that causes a decomposition and oxidation reaction of a fuel component with a temperature rise is achieved. An internal combustion engine capable of multistage compression ignition according to 4, 5, and 6.

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