JP2005291066A - Engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology capable of eliminating a clogging condition of an injection hole 25a of a fuel injection valve 25 under a condition that operation of the engine 100 continues with a simple structure in relation to the engine 100 performing injection ignition operation igniting air fuel mixture MG by injecting sub fuel SF from the fuel injection valve 25 and making the same self ignition combustion in a combustion chamber 1 compressing air fuel mixture MG of main fuel MF. <P>SOLUTION: This engine is provided with a clogging condition determination means 42 determining a clogging condition that an injection hole 25a is clogged by deposit and an addition means 55 adding additive R for eliminating clogging condition in sub fuel SF supplied to the fuel injection valve 25. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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.

JP 2000-64838 A

In the engine disclosed in Patent Document 1, for example, when the injection ignition operation is performed for a long time, the injection amount of the auxiliary fuel is very small, so that the penetration force of the auxiliary fuel passing through the injection hole of the fuel injection valve is small and the auxiliary fuel is used. Since the cooling effect of the nozzle tip is small, the liquid fuel is carbonized and deposited in the nozzle hole of the fuel injection valve, and the nozzle hole is easily clogged with deposits such as carbides. In addition, if the nozzle hole is clogged, problems such as misfires and engine stalls occur due to a decrease in the amount of secondary fuel injected. There was a need.

  Accordingly, the present invention has been made in view of the above circumstances, and the object of the present invention is, in a so-called pilot ignition engine, a clogged state of a nozzle hole of a fuel injection valve in a state where the operation of the engine is continued with a simple configuration. It is in providing a technology that can solve the problem.

  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. The first characteristic configuration is provided with an adding means capable of adding an additive for eliminating the clogged state to the auxiliary fuel supplied to the fuel injection valve. In the point.

  According to the first characteristic configuration, by adding the additive to the auxiliary fuel supplied to the fuel injection valve by the adding means, the injection of the auxiliary fuel by the fuel injection valve is continued and the injection ignition operation is continued. However, the carbides and the like attached to the injection hole of the fuel injection valve are removed by the action of the additive itself, and further, the injection amount is increased with the addition of the additive in order for the fuel injection valve to inject a certain amount of auxiliary fuel. By increasing it, the deposits can be blown away by the injection force of the fuel injection valve, and the clogged state of the injection hole of the fuel injection valve can be eliminated.

A second characteristic configuration of the engine according to the present invention includes a clogged state determining means for determining a clogged state in which the nozzle hole of the fuel injection valve is clogged with deposits,
The addition unit is configured to add the additive to the auxiliary fuel when the clogging state determination unit determines the clogging state.

  According to the second characteristic configuration, when the clogging state determining means determines that the fuel injection valve is clogged, the additive is added to the auxiliary fuel by the adding means, and the fuel injection is performed. When it is determined that the clogged state of the fuel injection valve has been eliminated by the clogged state determining means by eliminating the clogged state of the nozzle hole of the valve, without adding the additive to the auxiliary fuel by the adding means, The consumption of the additive can be saved, and further, the reduction in combustion efficiency due to the auxiliary fuel additive can be suppressed.

  A third characteristic configuration of the engine according to the present invention lies in that the clogged state determining means is configured to determine the clogged state based on an injection amount of sub fuel by the fuel injection valve.

  According to the third characteristic configuration, the clogging state determination means performs injection based on the injection amount of the auxiliary fuel of the fuel injection valve that changes due to the amount of deposits attached to the injection hole of the fuel injection valve. This can be realized by a simple configuration in which the clogged state is determined when the amount falls below a threshold value.

  In order to achieve the above object, a fourth characteristic configuration of the engine according to the present invention is that the additive is water.

  According to the fourth characteristic configuration, by adding water as an additive to the auxiliary fuel injected into the fuel injection valve by the adding means, the fuel is generated by the sensible heat and latent heat of the water injected together with the auxiliary fuel by the fuel injection valve. The injection hole of the injection valve can be cooled satisfactorily, and deposits can be made difficult to adhere. Moreover, since the water is discharged well together with the exhaust gas without accumulating in the combustion chamber, the amount of water added is increased to the same level as that of the auxiliary fuel, so that the injection of the mixture of the auxiliary fuel and water of the fuel injection valve The amount becomes large, and the deposits on the nozzle holes can be removed well by blowing off with the injection force of the mixture.

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.

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 clogged state determining means and the adding means can be provided to eliminate the clogged state of the injection hole of the fuel injection valve provided in the sub chamber while the engine is continuously operated. it can.

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 that is sub-combustible in order to inject a relatively large amount of liquid fuel in order 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 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, so that the operation is continued.

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 sub 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 the engine 100, since the injection amount of the auxiliary fuel SF by the fuel injection valve 25 is very small, liquid fuel stays in the injection hole 25a of the fuel injection valve 25 and carbonizes, and the fuel injection valve is caused by deposits such as carbides. Thus, the 25 nozzle holes 25a are easily clogged.

  Therefore, the ECU 40 functions as a clogging state determination unit 42 that determines a clogged state in which the nozzle hole 25a of the fuel injection valve 25 is clogged with deposits, and further, the sub fuel supply unit 50 of the engine 100 has a clogged state. An adding means 55 is provided for adding an additive R for eliminating the clogged state to the auxiliary fuel SF supplied to the fuel injection valve 25 when the determining means 42 determines the clogged state.

  Specifically, the clogging state determination means 42 is the number of cycles per unit time in which the flow rate can be recognized by the engine speed from the flow rate of the secondary fuel SF measured by the flow meter 52 provided in the secondary fuel supply path 54. By dividing by, the sub fuel injection amount which is the amount of the sub fuel SF injected by the fuel injection valve 25 per cycle is recognized. The fuel injection valve 25 injects the fuel injection valve 25 when the sub fuel injection amount of the fuel injection valve 25 recognized in this way is not an appropriate injection amount when the fuel injection valve 25 is not in a clogged state but falls below a predetermined threshold value. It is determined that the hole 25a is clogged.

On the other hand, the adding means 55 mixes the additive tank 56 for storing the additive R and the additive R with respect to the auxiliary fuel SF at a predetermined ratio upstream of the flow meter 52 of the auxiliary fuel supply path 54. The supply path 57 and the supply valve 58 capable of intermittently supplying the additive R to the auxiliary fuel SF are configured.
The ECU 40 is configured to add the additive R to the auxiliary fuel SF at a predetermined ratio by opening the supply valve 58 in the adding means 55 when the clogged state determining means 42 determines that the clogged state is present. Further, the injection amount of the fuel injection valve 25 is increased according to the addition ratio so that the heat amount of the sub fuel SF injected from the fuel injection valve 25 does not change due to the mixing of the additive R.

Then, in the injection hole 25a of the fuel injection valve 25, deposits such as carbides are removed by the action of the additive R itself and the action of an increase in the injection amount, and the clogged state is eliminated. The sub fuel injection amount of the valve 25 can be made appropriate.
In addition, when the ECU 40 determines that the clogged state has been eliminated by the clogged state determining unit 42, the ECU 40 stops the mixing of the additive R into the auxiliary fuel SF by closing the supply valve 58 in the adding unit 55 and fuel injection. The injection amount of the valve 25 is reduced to a normal amount.

  Moreover, water can be used as the additive R, and the fuel injection valve 25 can be configured to supply water as the additive R and an emulsion fuel of the auxiliary fuel SF. For example, when light oil is used as the auxiliary fuel SF, for example, the mixing ratio of water as the additive R with respect to the auxiliary fuel SF can be made equal. In addition, in this way, by mixing the same amount of water as the auxiliary fuel SF in the deposit removal operation, the nozzle hole 25a of the fuel injection valve 25 is cooled well, and it becomes difficult for the carbide to adhere to the fuel injection valve. Since the injection amount of the valve 25 is doubled, the deposit on the nozzle hole 25a is well blown away by the jet power of the mixture and removed.

[Another embodiment]
(1) In the above embodiment, the clogging state determination means 42 is configured to determine the clogging state based on the sub fuel injection amount of the fuel injection valve 25. For example, the clogging state determination unit 42 is clogged based on the engine load fluctuation rate. Another configuration such as determining the state may be adopted.
For example, when determining a clogged state based on the fluctuation rate of the engine load, the fuel injection valve continues when the fluctuation rate of the engine load rises above a predetermined threshold value for a predetermined allowable time. It is possible to determine the clogged state by determining that the fluctuation rate of the engine load is increased due to clogging of the 25 nozzle holes 25a.

(2) In the above embodiment, water is used as the additive R. However, as the additive R, a material other than water may be used. For example, as additive R, a detergent additive for lubricating oil such as neutral salt type calcium sulfonate, an extreme pressure additive such as sulfurized olefin, and the like can be used. It is preferable to add about several wt% with respect to the auxiliary fuel SF.

(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.
Further, the spark plug 30 may not be provided.

(4) 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. .

(5) 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 25a: Injection hole 30: Spark plug 40: Engine control unit (ECU)
41: Engine speed setting means 42: Clogging state determination means 50: Sub fuel supply means 55: Addition means 100: Engine MF: Main fuel SF: Sub fuel MG: Air-fuel mixture R: Additive

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 the auxiliary fuel from the fuel injection valve and performing self-ignition combustion,
An engine comprising an adding means capable of adding an additive for eliminating the clogged state to the auxiliary fuel supplied to the fuel injection valve. A clogging state determining means for determining a clogged state in which the nozzle hole of the fuel injection valve is clogged with deposits;
The engine according to claim 1, wherein the addition unit is configured to add the additive to the auxiliary fuel when the clogging state determination unit determines the clogging state.   The engine according to claim 2, wherein the clogging state determination unit is configured to determine the clogging state based on an injection amount of sub fuel by the fuel injection valve.   The engine according to any one of claims 1 to 3, wherein the additive is water. 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.

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