JP4386781B2 - engine - Google Patents

Description

  The present invention relates to an engine that performs an injection ignition operation of igniting the air-fuel mixture by injecting auxiliary fuel from a fuel injection valve and performing self-ignition combustion in a combustion chamber in which the air-fuel mixture of main fuel and oxygen-containing gas is compressed. .

In a combustion chamber in which a mixture of main fuel such as natural gas and air (oxygen-containing gas) is compressed, auxiliary fuel such as light oil and kerosene is injected from the fuel injection valve and self-ignition combustion is performed to ignite the mixture. An engine that performs an injection ignition operation to be performed (the above-mentioned sub fuel is sometimes referred to as an ignition pilot fuel, and therefore, such an engine is sometimes referred to as a pilot ignition engine) is known (for example, Patent Document 1). See).
In addition, in such an injection ignition operation, such an engine performs self-ignition by injecting secondary fuel by the fuel injection valve for ignition of the air-fuel mixture consisting of main fuel. It differs from a diesel engine in that the ratio is as small as a few percent.

  In the engine as described above, the air-fuel mixture consisting of the main fuel can be stably ignited by the thermal energy generated by the self-ignition combustion of the auxiliary fuel, so that the average effective pressure in the combustion chamber is increased and the efficiency is increased. Furthermore, since the air-fuel mixture comprising the main fuel can be stably lean burned at a relatively low equivalent ratio, NOx reduction can be achieved.

  Further, the engine disclosed in Patent Document 1 is provided with one ignition plug in the combustion chamber, and when the secondary fuel self-ignition in the combustion chamber does not occur stably during the starting operation, the ignition plug is operated. The spark ignition operation for igniting the air-fuel mixture composed of the main fuel is performed. In addition, even if the self-ignition of the auxiliary fuel injected from the fuel injection valve is started and the injection ignition operation is started, the ignition plug is continuously operated to ignite the air-fuel mixture comprising the main fuel. It is configured to assist.

JP 2000-64838 A

  In the engine described in Patent Document 1, when the ignition ignition is started by starting the self-ignition of the auxiliary fuel injected from the fuel injection valve in the state in which the ignition plug is operated during the start-up operation, The combustion period of the fuel becomes too short, and knocking or the like may occur.

  On the other hand, even in a no-load state where the load on the engine is cut off, the pressure in the combustion chamber is relatively low, so it is conceivable that the spark plug is operated by spark ignition operation to spark the mixture. Even in this case, the state of the sub fuel injected from the fuel injection valve is increased when the pressure of the combustion chamber rises in the state where the engine is shifted from the no-load state to the applied state where the load is applied to the engine and the ignition plug is operated. When ignition is started and injection ignition operation is started, the combustion period of the air-fuel mixture becomes too short, and knocking or the like may occur.

  Further, in order to avoid the knocking as described above, if the operation of the spark plug is stopped when the self-ignition of the sub fuel injected from the fuel injection valve is started, the sub chamber into which the sub fuel is injected is sufficiently provided. Due to reasons such as not being warmed up, the self-ignition of the secondary fuel may become unstable and misfire or engine stall may occur.

  Further, in spark ignition operation, if the ignition energy of the spark plug to be operated is too small, the exhaust gas burned due to misfire or the combustion period of the air-fuel mixture being prolonged is discharged to the exhaust passage at a high temperature of about 700 ° C., for example. It may be done.

  Accordingly, the present invention has been made in view of the above circumstances, and its purpose is to perform a smooth transition between a spark ignition operation and an injection ignition operation in a so-called pilot ignition engine, and further to spark ignition. The object of the present invention is to provide a technique capable of appropriately burning the air-fuel mixture during operation and avoiding misfire and high exhaust gas temperature.

In order to achieve the above object, an engine according to the present invention includes a combustion chamber in which an air-fuel mixture of main fuel and oxygen-containing gas is compressed. An engine that performs an injection ignition operation for igniting the engine, wherein the first characteristic configuration includes a plurality of spark plugs in the combustion chamber,
At the time of start-up operation or no-load operation, it is configured to perform a spark ignition operation in which an air-fuel mixture compressed in the combustion chamber is ignited by operating all of the plurality of spark plugs,
Transition from partial ignition operation in which the air-fuel mixture compressed in the combustion chamber is ignited by activating only some of the plurality of ignition plugs at the time of transition between the spark ignition operation and the injection ignition operation. It exists in the point comprised so that it may perform as a driving | operation.

According to the first characteristic configuration described above, during the start-up operation or the no-load operation, by performing a spark ignition operation that operates a plurality of spark plugs, the ignition energy is sufficiently increased so that an air-fuel mixture composed of main fuel is generated. Since it can ignite stably, misfire and high temperature of exhaust gas can be avoided.
Further, when the partial ignition operation is performed as the transition operation performed at the time of transition between the spark ignition operation and the injection ignition operation, the self-ignition of the auxiliary fuel injected from the fuel injection valve is unstable. In this case, knocking can be avoided by reducing ignition energy as much as possible while assisting the ignition of the air-fuel mixture by the ignition energy of some spark plugs and stably burning the air-fuel mixture, so that spark ignition operation and injection The transition between the ignition operation can be performed smoothly.

  A second characteristic configuration of the engine according to the present invention is that the fuel injection valve is disposed in a central portion of the combustion chamber, and the plurality of spark plugs are disposed symmetrically about the central portion of the combustion chamber. .

  According to the second characteristic configuration, when a plurality of spark plugs are provided, a spark ignition operation is performed by arranging the plurality of spark plugs symmetrically about the center of the combustion chamber in which the fuel injection valve is disposed. When the air-fuel mixture is ignited by operating all of the plurality of spark plugs, the air-fuel mixture is combusted in a uniform state in the combustion chamber. High temperature can be further suppressed.

In order to achieve the above object, a third characteristic configuration of the engine according to the present invention includes an ignition plug in the combustion chamber, and a preheating plug in a region in which auxiliary fuel is injected by the fuel injection valve in the combustion chamber. ,
At the time of start-up operation or no-load operation, it is configured to perform a spark ignition operation in which the air-fuel mixture compressed in the combustion chamber is ignited by the spark plug,
Preheat injection in which the auxiliary fuel injected by the fuel injection valve is self-ignited and burned in a state where the operation of the spark plug is stopped and the preheat plug is operated at the time of transition between the spark ignition operation and the injection ignition operation. The ignition operation is performed as the transition operation.

  According to the third characteristic configuration, when performing a spark ignition operation that operates a plurality or a single spark plug during the start-up operation or no-load operation, the transition between the spark ignition operation and the injection ignition operation is performed. By performing the preheat injection ignition operation as a transition operation that is sometimes performed, at the time of transition where the self-ignition of the auxiliary fuel injected from the fuel injection valve is unstable, the auxiliary fuel is reliably burned by the preheating plug. However, knocking can be avoided by stopping the spark plug, and the transition between the spark ignition operation and the injection ignition operation can be performed smoothly.

A fourth characteristic configuration of the engine according to the present invention includes an exhaust gas state detection means for detecting an exhaust gas state discharged from the combustion chamber,
There is a transition timing determination means for determining a transition timing among the spark ignition operation, the transition operation, and the injection ignition operation based on the detection result of the exhaust gas state detection means.

The transition timing among the spark ignition operation, the transition operation, and the injection ignition operation that has been described so far may be determined by determining each operation time in advance and passing that time. According to the characteristic configuration, it is possible to determine the transition time based on the change in the exhaust gas state detected by the exhaust gas state detection means. Even when the engine operating environment or the like changes, the transition time is appropriately set according to the change. It can be time.
For example, when the exhaust gas temperature detection means detects the exhaust gas temperature and oxygen concentration as the exhaust gas condition, has the sub fuel injected into the combustion chamber started to self-ignite due to a decrease in the exhaust gas temperature or oxygen concentration? So that the transition operation is performed when the self-ignition is started but is still unstable, and the injection ignition operation is performed when the self-ignition is stable. The transition time can be determined.

A fifth characteristic configuration of the engine according to the present invention includes, as the combustion chamber, a main chamber formed in a cylinder, and a sub chamber formed in a cylinder head and communicating with the main chamber.
The fuel injection valve is disposed in the sub chamber, and the spark plug is disposed in the main chamber.

According to the fifth feature, the main chamber and the sub chamber are provided as combustion chambers, and the fuel injection valve is disposed in the sub chamber, so that the sub fuel injected into the sub chamber is diffused throughout the combustion chamber. The sub-chamber can be successfully self-ignited and combusted while suppressing the occurrence of this, and the flame jet generated by the self-igniting combustion is injected into the main chamber, for example, to ignite the low-equivalent gas mixture in the main chamber. Can be made.
Even in such an engine, the transition can be smoothly performed by performing the transition operation described above between the spark ignition operation and the injection ignition operation.

An embodiment of the present invention will be described with reference to FIGS.
The engine 100 includes a piston 2 and a cylinder 3 that accommodates the piston 2. The engine 100 is formed in the cylinder 3 by reciprocating the piston 2 in the cylinder 3 and opening and closing the intake valve 4 and the exhaust valve 5. In the combustion chamber 1, intake, compression, combustion / expansion, and exhaust strokes are performed, and the reciprocating motion of the piston 2 is output as the rotational motion of the crankshaft 17. Such a configuration has a normal 4-stroke. There is no difference from an internal combustion engine.

The engine 100 forms a mixture MG of main fuel MF, which is a natural gas mainly composed of methane, and air in the intake passage 6, opens the intake valve 4 in the intake stroke, and opens the mixture from the intake passage 6. MG is sucked into the combustion chamber 1, the exhaust valve 5 is closed in the compression stroke to compress the intake air-fuel mixture MG, and the compressed mixture is ignited and burned in the combustion / expansion stroke. The exhaust valve 5 is opened, and the exhaust gas after combustion is discharged to the exhaust passage 7.
The equivalence ratio of the air-fuel mixture MG is set to be less than 1, preferably in the range of 0.5 to 0.7.

  Unlike the main fuel MF sucked from the intake passage 6, the combustion chamber 1 is combusted with a sub fuel SF such as light oil or kerosene, which is a liquid fuel superior in ignitability than the main fuel MF, at the end of the compression stroke. A fuel injection valve 25 is provided in the chamber 1 for high-pressure injection and self-ignition.

  The fuel injection valve 25 can adopt the same configuration as that of, for example, a common rail type fuel injection mechanism used in a general diesel engine or the like, and burns the auxiliary fuel SF supplied in a highly compressed state. It is configured to inject into the chamber 1.

  However, the fuel injection mechanism for the diesel engine has a secondary fuel injection valve 25 in which a relatively large amount of liquid fuel is injected to push down the piston by diffusing and burning high pressure injected liquid fuel. The difference is that the injection amount of the fuel SF is very small.

  That is, in the engine 100 of the present embodiment, at the end of the compression stroke, a small amount of sub fuel SF is injected into the combustion chamber 1 from the fuel injection valve 25 at high pressure and self-ignition combustion is performed. The air-fuel mixture MG sucked from the intake passage 6 is stably ignited and burned by the heat energy generated by the self-ignition combustion of the fuel MF, and the piston 2 is pushed down by the combustion to continue the operation.

The injection amount of the auxiliary fuel SF by the fuel injection valve 25 is in the range of 0.2% or more and 5% or less, preferably in the range of 1% or less, in terms of the heat amount ratio to the total heat amount of the main fuel MF and the auxiliary fuel SF It is said.
That is, if the calorie ratio of the injection amount of the auxiliary fuel SF to the total heat amount is smaller than 0.2%, the amount of heat generated by the self-ignition combustion is too small to stably ignite the mixture MG. Misfire may occur. On the other hand, if it is larger than 5%, the amount of heat generated by the self-ignition combustion is too large, the maximum pressure of the combustion chamber 1 becomes excessively large and knocking may occur. Since the consumption amount of the sub fuel SF with respect to the main fuel MF is increased, the size of the apparatus is increased by increasing the size of the tank or the like for storing the sub fuel SF.
Further, by making the heat amount ratio of the injection amount of the auxiliary fuel SF to the total heat amount 1% or less, further miniaturization can be achieved while avoiding misfire and knocking as described above.

  By adopting the above-described configuration, the engine 100 is injected from the fuel injection valve 25 at high pressure with a mixture MG having an equivalence ratio of 0.5 to 0.7 using natural gas or the like as the main fuel MF. Since a small amount of auxiliary fuel MF can be stably ignited by self-ignition combustion, the indicated mean effective pressure in the combustion chamber 1 can be increased to achieve high output and high efficiency.

Further, the auxiliary fuel supply means 50 for supplying the auxiliary fuel SF to the fuel injection valve 25 will be described. The auxiliary fuel SF is stored in the auxiliary fuel tank 53 and stored in the auxiliary fuel tank 53. The auxiliary fuel SF is highly compressed by the fuel pump 51 driven by using the rotational power of the crankshaft 17 in the auxiliary fuel supply path 54 and supplied to the fuel injection valve 25.
Further, the injection amount of the auxiliary fuel SF by the fuel injection valve 25 is adjusted by adjusting the operation of the fuel injection valve 25 itself. The injection amount in the fuel injection valve 25 can also be adjusted by adjusting the governor provided in the auxiliary fuel supply path 54 and adjusting the pressure of the auxiliary fuel SF supplied to the fuel injection valve 25.
The auxiliary fuel supply path 54 is provided with a flow meter 52 for measuring the flow rate of the auxiliary fuel SF.

  Further, the engine 100 of the present embodiment includes a main chamber 11 defined by the inner surface of the cylinder 3, the top surface of the piston 2, and the lower surface of the cylinder head 9 as the combustion chamber 1, and the central portion of the cylinder head 9 (the cylinder 3 And a sub chamber 21 formed in the sub chamber base 20 provided in the portion of the sub chamber base 20, and the main chamber 11 and the sub chamber 21 are connected to the main chamber 11 of the sub chamber base 20. It communicates via the communication hole 22 formed in the protrusion part. The volume ratio of the sub chamber 21 is preferably about 2% to 20% of the entire combustion chamber 1.

  Furthermore, a concave portion 2a is formed in the central portion of the top surface of the piston 2 so as to surround the sub-chamber base 20 protruding into the main chamber 11 when the piston 2 is located at the top dead center. Thus, when the piston 2 rises in the compression stroke, squish flowing from the outer peripheral portion of the top surface of the piston 2 to the central portion of the recess 2a is generated.

  Further, the fuel injection valve 25 is provided above the sub chamber base 20 and configured to inject the sub fuel SF into the sub chamber 21 at a high pressure.

  That is, the engine 100 employs the above-described configuration, thereby compressing the air-fuel mixture MG sucked into the main chamber 11 as the piston 2 rises, and opening the compressed air-fuel mixture MG into the main chamber 11. The fuel MG is injected into the sub-chamber 21 through the communicating hole 22 and compressed in the sub-chamber 21, and the fuel injection valve 25 injects the sub-fuel SF to cause self-ignition combustion to form a flame. Is injected into the main chamber 11 from the sub chamber 21 through the communication hole 22 as a flame jet FJ, and the so-called injection ignition operation is performed in which the air-fuel mixture MG in the main chamber 11 is ignited and burned by the flame jet FJ. Has been.

  The engine 100 is provided with an engine control unit (hereinafter referred to as an ECU) 40 comprising a computer. The ECU 40 detects the engine speed based on the detection result of the crank angle sensor 16 that measures the rotation angle of the crankshaft 17. The amount of intake air of the mixture MG into the combustion chamber 1 is adjusted by adjusting the opening of the throttle valve 15 provided in the intake passage 6 so that the engine speed is set within a desired target speed range. The engine speed setting means 41 to be adjusted is configured to function.

  As shown in FIG. 2, in the engine 100, the fuel injection valve 25 is disposed in the central portion of the combustion chamber 1, and a plurality of, specifically, two spark plugs 30 are symmetrically disposed around the central portion of the combustion chamber 1. Further, the fuel injection valve 25 is disposed in the sub chamber 21, and the plurality of spark plugs 30 are disposed in the main chamber 11. Further, these spark plugs 30 are operated by the ECU 40 when the self-ignition of the auxiliary fuel SF and the ignition of the air-fuel mixture MG are not stable in the combustion chamber 1 during start-up operation or no-load operation, for example. The air-fuel mixture MG sucked into the chamber 11 is stably ignited and burned.

In particular, during the start-up operation of the engine 100, the combustion chamber 1 is not sufficiently heated, and the pressure of the auxiliary fuel SF supplied to the fuel injection valve 25 is not sufficiently increased. Even if the auxiliary fuel SF is injected by the fuel injection valve 25, the auxiliary fuel SF may not self-ignite.
Even when the engine load applied to the crankshaft 17 of the engine 100 is shut off, the pressure in the combustion chamber 1 is relatively low, so that an injection ignition operation is performed and the sub fuel SF is injected by the fuel injection valve 25. Even so, the secondary fuel SF may not self-ignite.

  Therefore, the ECU 40 functions as an operation control means 42 for performing a spark ignition operation in which the air-fuel mixture MG compressed in the combustion chamber 1 is ignited by operating the ignition plug 30 during the start-up operation or the no-load operation. It is configured.

  That is, the operation control means 42 first operates the spark plug 30 while rotating the crankshaft 17 by the motor 8 when the engine start command is inputted and the start operation for starting the engine 100 is performed. Thus, by performing the spark ignition operation, the mixture MG is spark-ignited and burned by the spark ignition of the spark plug 30, and the engine 100 is sufficiently warmed up by the combustion of the mixture MG. By starting the injection of the auxiliary fuel SF from the fuel injection valve 25 from the initial stage or the middle stage of the spark ignition operation, the warm-up of the engine 100 proceeds, and the auxiliary fuel SF starts self-igniting combustion.

  When the self-ignition combustion of the sub fuel SF injected by the fuel injection valve 25 is in a stable state, the operation control means 42 stops the operation of the spark plug 30 and the sub fuel SF. Is shifted to the injection ignition operation in which the air-fuel mixture MG composed of the main fuel MF is ignited by self-ignition combustion.

  In addition, the operation control means 42 performs the spark ignition operation by operating the spark plug 30 even when the engine load 36 is cut off and becomes a no-load state. When the engine load 36 is applied, the operation of the spark plug 30 is stopped, and the injection ignition operation in which the air-fuel mixture MG composed of the main fuel MF is ignited by the self-ignition combustion of the auxiliary fuel SF. Transition.

  Furthermore, at the time of transition from the spark ignition operation to the injection ignition operation, the self-ignition of the auxiliary fuel injected from the fuel injection valve may be unstable. Therefore, the operation control means 42 is configured to make the transition smooth by performing a predetermined transition operation at the time of the transition.

  That is, in the spark ignition operation, the operation control unit 42 operates the spark plug 30 to operate the spark plugs 30 to ignite the air-fuel mixture MG. A part of the plurality of spark plugs 30 is specifically configured to perform a partial ignition operation in which only one spark plug 30 is operated and ignited. By performing this partial ignition operation as a transition operation, Further, knocking can be avoided by reducing the ignition energy as much as possible while assisting the ignition of the air-fuel mixture MG with the ignition energy of some of the spark plugs 30 to stably burn the air-fuel mixture MG.

Note that, as described above, in the spark ignition operation, the mixture gas MG is spark-ignited by the plurality of spark plugs 30, so that the combustion period of the mixture gas MG is suppressed from being prolonged, and the temperature of the exhaust gas discharged to the exhaust passage 7. Can be lowered to about 600 ° C.
Further, when the self-ignition of the sub fuel SF injected by the fuel injection valve 25 is started and the injection ignition operation is started, the temperature of the exhaust gas discharged to the exhaust passage 7 because the combustion period of the air-fuel mixture MG is further shortened. Is further lowered to about 450 ° C.
Incidentally, when the mixture MG is spark-ignited with only one spark plug 30 in the spark ignition operation, the combustion period of the mixture MG is prolonged, and the exhaust gas is discharged to the exhaust passage 7 at a high temperature of about 700 ° C., for example. Will be.

  Further, a preheating plug 32 is provided in a region where the sub fuel SF is injected by the fuel injection valve 25 of the combustion chamber 1, that is, the sub chamber 21, and the operation control means 42 is provided between the spark ignition operation and the injection ignition operation. The transition operation is configured to perform a preheat injection ignition operation in which the auxiliary fuel SF injected by the fuel injection valve 25 is self-ignited and burned in a state where the operation of the spark plug 30 is stopped and the preheat plug 32 is operated, By performing this preheating injection ignition operation as a transition operation, knocking can be avoided by stopping the spark plug 30 while reliably burning the auxiliary fuel SF by the preheating plug 32.

  The operation control means 42 can be configured to perform only one of the partial ignition operation and the preheat injection ignition operation as the transition operation. For example, in the transition operation, first, the partial ignition operation is performed. It can comprise so that the said preheating injection ignition driving | operation may be performed later.

  Further, at the time of transition between the spark ignition operation and the injection ignition operation, the injection of the sub fuel SF by the fuel injection valve 25 can be continued, but the injection of the sub fuel SF is stopped in the spark ignition operation, for example, Prior to the transition, the injection of the auxiliary fuel SF may be resumed.

Further, in the exhaust path 7 of the engine 100, as an exhaust gas state discharged from the combustion chamber 1, a temperature sensor 34 (an example of exhaust gas state detection means) that detects the temperature of the exhaust gas E and an oxygen concentration of the exhaust gas E are detected. An oxygen concentration sensor 35 (an example of exhaust gas state detection means) is provided.
Then, the ECU 40 shifts between the spark ignition operation, the transition operation, and the injection ignition operation based on the temperature or oxygen concentration of the exhaust gas E as the exhaust gas state detected by the temperature sensor 34 and the oxygen concentration sensor 35. It is configured to function as a transition time determination means 43 that determines the time.
That is, the transition timing determination means 43 indicates that the combustion chamber 1 is in a state in which the auxiliary fuel SG can be stably self-ignited and combusted when the temperature or oxygen concentration of the exhaust gas E falls below a predetermined threshold value. Recognizing it, it can be determined that it is the transition timing from the spark ignition operation to the transition operation or the transition timing from the transition operation to the injection ignition operation.
Note that the switching from the spark ignition operation to the transition operation significantly reduces the temperature of the exhaust gas E, which was about 600 ° C. in the spark ignition operation, to about 450 ° C. when the self-ignition combustion of the auxiliary fuel SF is started. This is preferably performed when the temperature of the exhaust gas E falls below a threshold value slightly higher than 450 ° C.

Further, when the engine 100 is warmed up during the start-up operation and the air-fuel mixture MG is stably ignited in the combustion chamber 1, the engine speed and the engine output become stable.
Therefore, the transition time determination means 43 monitors the engine speed recognized from the engine output or the detection result of the crank angle sensor 16, and the warm-up of the engine 100 proceeds when the dispersion thereof becomes a predetermined threshold value or less. It may be determined that it is the transition timing from the spark ignition operation to the injection ignition operation through the transition operation.

[Another embodiment]
(1) In the above embodiment, two spark plugs 30 that are operated in the spark ignition operation are provided. However, three or more spark plugs may be separately provided and operated in the spark ignition operation.
Further, when operating three or more spark plugs in the spark ignition operation, the spark plugs can be operated in such a manner that the number of spark plugs operated in the partial ignition operation is reduced stepwise by one or more.

(2) In the above embodiment, at the time of transition between the spark ignition operation and the injection ignition operation, both the partial ignition operation and the preheating injection ignition operation are performed. It doesn't matter. Further, when the preheating injection ignition operation is not performed, the preheating plug 32 can be omitted, and the number of ignition plugs 30 that are operated in the spark ignition operation may be one.

(3) In the above embodiment, the fuel injection valve 25 is disposed in the sub chamber 21 disposed in the central portion of the combustion chamber 1, and the spark plug 30 is centered on the central portion of the main chamber 11 as the combustion chamber 1. However, the arrangement of the fuel injection valve 25 and the spark plug 30 can be modified as appropriate.

(4) In the above embodiment, the transition timing determination means 43 for determining the transition timing among the spark ignition operation, the transition operation, and the injection ignition operation using the temperature and oxygen concentration of the exhaust gas E is provided. Each transition time of the ignition operation, the transition operation, and the injection ignition operation may be determined in advance, and the transition timing may be determined by the passage of the operation time.

(5) Although the main chamber 11 and the sub chamber 21 are provided as the combustion chamber 1 in the above embodiment, the combustion chamber 1 may be configured only by the main chamber 11 without providing the sub chamber 21 separately. .

(6) In the above embodiment, natural gas is used as the main fuel MF, and light oil or kerosene is used as the auxiliary fuel SF. However, the main fuel MF and the auxiliary fuel SF can be modified as appropriate. In particular, since the auxiliary fuel SF is injected into the combustion chamber 1 in a high pressure state and self-ignited, it is preferable to use a liquid fuel excellent in ignitability.

The figure which shows the side cross section and schematic structure of the combustion chamber part of an engine Side sectional view of the combustion chamber part of the engine Cross section of engine combustion chamber

Explanation of symbols

1: Combustion chamber 11: Main chamber (combustion chamber)
15: Throttle valve 16: Crank angle sensor 21: Sub chamber (combustion chamber)
22: Communication hole 25: Fuel injection valve 30: Spark plug 32: Preheating plug 34: Temperature sensor (exhaust gas state detection means)
35: Oxygen concentration sensor (exhaust gas state detection means)
36: Engine load 40: Engine control unit (ECU)
41: Engine speed setting means 42: Operation control means 43: Transition timing determination means 50: Sub fuel supply means 100: Engine MF: Main fuel SF: Sub fuel MG: Air-fuel mixture

Claims (5)

In the combustion chamber in which the mixture of the main fuel and the oxygen-containing gas is compressed, the engine performs an injection ignition operation of igniting the mixture by injecting auxiliary fuel from the fuel injection valve and performing self-ignition combustion,
A plurality of spark plugs in the combustion chamber;
At the time of start-up operation or no-load operation, it is configured to perform a spark ignition operation in which an air-fuel mixture compressed in the combustion chamber is ignited by operating all of the plurality of spark plugs,
Transition from partial ignition operation in which the air-fuel mixture compressed in the combustion chamber is ignited by activating only some of the plurality of ignition plugs at the time of transition between the spark ignition operation and the injection ignition operation. An engine that is configured to run as a run.   2. The engine according to claim 1, wherein the fuel injection valve is disposed in a central portion of the combustion chamber, and the plurality of spark plugs are disposed symmetrically about the central portion of the combustion chamber. In the combustion chamber in which the mixture of the main fuel and the oxygen-containing gas is compressed, the engine performs an injection ignition operation of igniting the mixture by injecting the auxiliary fuel from the fuel injection valve and performing self-ignition combustion,
A spark plug is provided in the combustion chamber, and a preheating plug is provided in a region where auxiliary fuel is injected by the fuel injection valve of the combustion chamber,
At the time of start-up operation or no-load operation, it is configured to perform a spark ignition operation in which the air-fuel mixture compressed in the combustion chamber is ignited by the spark plug,
Preheat injection in which the auxiliary fuel injected by the fuel injection valve is self-ignited and burned in a state where the operation of the spark plug is stopped and the preheat plug is operated at the time of transition between the spark ignition operation and the injection ignition operation. An engine configured to perform an ignition operation as a transition operation. An exhaust gas state detection means for detecting the exhaust gas state discharged from the combustion chamber;
4. The apparatus according to claim 1, further comprising a transition timing determination unit that determines a transition timing among the spark ignition operation, the transition operation, and the injection ignition operation based on a detection result of the exhaust gas state detection unit. Engine described in. The combustion chamber includes a main chamber formed in a cylinder, and a sub chamber formed in a cylinder head and communicating with the main chamber.
The engine according to any one of claims 1 to 4, wherein the fuel injection valve is disposed in the sub chamber, and the spark plug is disposed in the main chamber.

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