JP6020266B2 - Gaseous fuel combustion control system and gaseous fuel combustion control method - Google Patents

Description

The present invention, gaseous fuel combustion control system controls the combustion state of the gas fuel supplied to the combustion chamber of an internal combustion engine, and to a gas-body fuel combustion control method.

  Conventionally, an internal combustion engine for gaseous fuel using a hydrocarbon gas such as methane as a fuel is known. The hydrocarbon gas supplied to the combustion chamber of the internal combustion engine for gaseous fuel is difficult to mix with air and has a narrow flammable range, so that it does not burn in an air-fuel mixture whose equivalence ratio is smaller than the stoichiometric equivalence ratio. For this reason, in combustion of an internal combustion engine for gaseous fuel, when supplying a mixture of hydrocarbon gas and air to the combustion chamber, a layer of the mixture containing a relatively small proportion of hydrocarbon gas is placed near the inner wall of the combustion chamber. A “stratified combustion method” is used in which an air-fuel mixture layer containing a hydrocarbon gas in a proportion suitable for ignition is formed in the vicinity of the spark plug while being formed. In Patent Document 1, two fuel injection valves are provided in an intake pipe, and hydrocarbon gas injected from an upstream fuel injection valve is uniformly diffused into a combustion chamber and injected from a downstream fuel injection valve. A gas fuel supply device is described in which hydrocarbon gas is retained in the vicinity of a spark plug.

JP-A-10-220227

  However, in the gas fuel supply apparatus described in Patent Document 1, the upstream fuel injection valve mixes hydrocarbon gas and air by the venturi effect. For this reason, the supply amount of the hydrocarbon gas corresponding to the type of the hydrocarbon gas and the stoichiometric air-fuel ratio cannot be set, and the hydrocarbon gas cannot be burned efficiently. Further, in the gas fuel supply device described in Patent Document 1, since a mixture of hydrocarbon gas and air is supplied to the combustion chamber via the intake port, combustion is caused near the wall surface of the combustion chamber by the subsequent compression stroke. A possible air-fuel mixture layer is formed, which may lead to deterioration in cooling loss due to combustion in the vicinity of the wall surface and reduction in combustion efficiency due to extinction.

  The objective of this invention is providing the gaseous fuel combustion control system which can improve the combustion efficiency of the gaseous fuel supplied to an internal combustion engine.

The present invention relates to a gaseous fuel combustion control system for controlling the combustion of a gaseous fuel in an internal combustion engine, of an internal combustion engine, a fuel tank, an inner combustion engine air or air to form a swirl flow in the combustion chamber and exhaust A first intake pipe that supplies an air-fuel mixture, and an air or gas fuel / air mixture that forms a tumble flow in a combustion chamber of an internal combustion engine or an air / exhaust air mixture or a gas fuel / air / exhaust gas mixture When the second intake pipe for supplying air and the air or the air-fuel mixture supplied to the combustion chamber by the first intake pipe and the second intake pipe are compressed, the gaseous fuel or the mixture of gaseous fuel and air is A fuel injection valve that directly injects into the combustion chamber; an air supply means that supplies air to the fuel injection valve; Pressure adjusting hand to adjust When a pressure detecting means for outputting a signal corresponding to the magnitude of the pressure detected detected gaseous fuel the pressure of gaseous fuel supplied to the fuel injection valve, the crank angle detected by detecting the crank angle of the internal combustion engine Crank angle detection means for outputting a signal corresponding to the magnitude, and the pressure, injection time, and injection start time of the gaseous fuel injected by the fuel injection valve based on the signals output by the pressure detection means and the crank angle detection means And a ratio of the gaseous fuel contained in the gaseous fuel injected by the fuel injection valve or the mixture of gaseous fuel and air includes air or air supplied to the combustion chamber by the second intake pipe It is characterized by being larger than the ratio of gaseous fuel contained in the air-fuel mixture.

  In the gaseous fuel combustion control system of the present invention, the air-fuel mixture is supplied to the combustion chamber using the three intake systems of the first intake pipe, the second intake pipe, and the fuel injection valve. The first intake pipe supplies air or a mixture of air and exhaust to the combustion chamber and forms a swirl flow in the combustion chamber. The second intake pipe supplies air or a mixture of gaseous fuel and air or a mixture of air and exhaust or a mixture of gaseous fuel, air and exhaust to the combustion chamber to form a tumble flow. The fuel injection valve also includes air or air supplied to the combustion chamber by the second intake pipe when the air or air-fuel mixture supplied to the combustion chamber by the first intake pipe and the second intake pipe is compressed. A mixture of gaseous fuel containing gaseous fuel and air or only gaseous fuel is injected at a rate greater than the proportion of gaseous fuel contained in the mixture. Thus, in the gaseous fuel combustion control system of the present invention, in the compression stroke of the internal combustion engine, the gaseous fuel or the air-fuel mixture containing a relatively large amount of gaseous fuel is burned while compressing the air in the combustion chamber or the air-fuel mixture containing air. The gas fuel and air or the gas fuel, air and exhaust can be mixed. Also, the ratio of the gaseous fuel contained in the air-fuel mixture near the spark plug is the ratio of the air layer or gaseous fuel near the wall of the combustion chamber while forming a layer containing a relatively large amount of gaseous fuel near the ignition plug in the combustion chamber. Smaller layers can be formed. Therefore, in the gaseous fuel combustion control system of the present invention, an air-fuel mixture capable of “stratified combustion” that efficiently burns gaseous fuel can be formed in the combustion chamber.

1 is a conceptual diagram of a gaseous fuel combustion control system according to a first embodiment of the present invention. It is a schematic diagram of the gas engine of the gaseous fuel combustion control system by 1st Embodiment of this invention. It is a flowchart of the gaseous fuel combustion control method in the gaseous fuel combustion control system by 1st Embodiment of this invention. It is a characteristic view explaining the injection timing of the fuel in the fuel injection valve of the gaseous fuel combustion control system by 1st Embodiment of this invention. It is a conceptual diagram of the gaseous fuel combustion control system by 2nd Embodiment of this invention. It is a characteristic view explaining the methane gas supply amount in the gaseous fuel combustion control system by 2nd Embodiment of this invention. It is a schematic diagram explaining the effect | action of the gaseous fuel combustion control system by 3rd Embodiment of this invention. It is a schematic diagram explaining the effect | action of the gaseous fuel combustion control system by 3rd Embodiment of this invention, Comprising: It is a schematic diagram explaining the effect | action different from FIG. It is a schematic diagram explaining the effect | action of the gaseous fuel combustion control system by 3rd Embodiment of this invention, Comprising: It is a schematic diagram explaining the effect | action different from FIG. It is a conceptual diagram of the gaseous fuel combustion control system by 4th Embodiment of this invention.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
A gaseous fuel combustion control system according to a first embodiment of the present invention is shown in FIGS.
A gas fuel combustion control system 1 shown in FIG. 1 includes a gas engine 11 as an “internal combustion engine”, a fuel tank 21, a regulator 23, a fuel injection valve 31, a first intake pipe 41 (see FIG. 2), and a second intake pipe 42. And an electronic control unit (hereinafter referred to as “ECU”) 50 and the like. The gaseous fuel combustion control system 1 supplies methane gas as “gaseous fuel” in the fuel tank 21 to the combustion chamber 130 of the gas engine 11 by the fuel injection valve 31, while the first intake pipe 41 and the second intake pipe 42. Air is supplied to the combustion chamber 130 to form a mixture of methane gas and air capable of “stratified combustion” optimal for combustion in the combustion chamber 130. 1 and 2, the flow of intake and exhaust in the gas engine 11 is indicated by arrows S.

  The gas engine 11 includes a piston 12, a cylinder block 13, a connecting rod 14, a crankshaft 15, and the like. The piston 12, the connecting rod 14, and the crankshaft 15 are accommodated in the cylinder block 13.

  The cylinder block 13 accommodates the piston 12 so as to be able to reciprocate. As shown in FIG. 2, on one end side of the cylinder block 13, a first intake port 131, a second intake port 132, an injection valve through hole 134, a spark plug through hole 133, and two exhausts are provided. Ports 135 and 136 are formed. The fuel injection valve 31 is provided in the injection valve through hole 134. A spark plug 16 is provided in the spark plug through hole 133. Methane gas and air supplied to the combustion chamber 130 via the first intake port 131, the second intake port 132, and the fuel injection valve 31 are ignited and burned by the spark plug 16 and stay in the combustion chamber 130 after combustion. The exhaust gas is discharged to the outside through the exhaust ports 135 and 136 and the exhaust pipe 17 connected to the exhaust ports 135 and 136.

A crankshaft 15 is accommodated on the other end side of the cylinder block 13. The crankshaft 15 is connected to the piston 12 via a connecting rod 14. On the other end side of the cylinder block 13 in which the crankshaft 15 is accommodated, a rotation angle of the crankshaft 15 (hereinafter referred to as “crank angle”) is detected, and a signal corresponding to the detected crank angle is sent to the ECU 50. A rotation angle sensor 19 is provided as “crank angle detection means” for outputting.

The fuel tank 21 is connected to the fuel injection valve 31 via the gaseous fuel supply pipe 22. The gaseous fuel supply pipe 22 is provided with a regulator 23 and a pressure sensor 24. The methane gas stored in the fuel tank 21 is depressurized to a pressure at which the fuel injection valve 31 can inject by the regulator 23 as “pressure adjusting means” in accordance with a signal input from the ECU 50. The decompressed methane gas is supplied to the fuel injection valve 31 through the pressure sensor 24. The pressure sensor 24 as “pressure detection means” detects the pressure of methane gas in the gaseous fuel supply pipe 22 on the fuel injection valve 31 side, and outputs a signal corresponding to the detected pressure to the ECU 50.

  The fuel injection valve 31 is a so-called outer valve that is provided with a needle outside the nozzle hole and opens when the needle moves outward during injection. The fuel injection valve 31 is inserted into the injection valve through hole 134 and fixed to the cylinder block 13. The fuel injection valve 31 supplies methane gas to the combustion chamber 130 along the direction in which the piston 12 moves in accordance with a signal input from the ECU 50.

  The first intake pipe 41 is connected to the first intake port 131 and supplies air to the combustion chamber 130. The air supplied from the first intake pipe 41 to the combustion chamber 130 forms a swirl flow in the combustion chamber 130.

The second intake pipe 42 is connected to the second intake port 132. The second intake pipe 42 of the gaseous fuel combustion control system 1 according to the first embodiment supplies air to the combustion chamber 130. The air supplied from the second intake pipe 42 to the combustion chamber 130 forms a tumble flow in the combustion chamber 130.
The first intake pipe 41 and the second intake pipe 42 are connected to the upstream intake pipe 43 on the upstream side. The end of the upstream side intake pipe 43 opposite to the side connected to the first intake pipe 41 and the second intake pipe 42 is connected to the outside. A throttle valve 44 is provided in the upstream side intake pipe 43.

  The throttle valve 44 changes the throttle opening according to the amount of depression of the accelerator pedal 441 by the driver, and controls the flow rate of air flowing through the upstream side intake pipe 43. Further, the throttle valve 44 outputs a signal corresponding to the throttle opening to the ECU 50.

  The ECU 50 is a small computer having a CPU as a calculation unit, a ROM, a RAM as a storage unit, an input / output unit, and the like. As shown in FIG. 1, the ECU 50 as the “control means” includes a signal related to the throttle opening of the throttle valve 44, a signal related to the pressure of methane gas in the gaseous fuel supply pipe 22 detected by the pressure sensor 24, and a rotation angle. A signal related to the crank angle detected by the sensor 19 is input. Based on these signals, the ECU 50 calculates the pressure of the methane gas controlled by the regulator 23 and the timing at which the fuel injection valve 31 supplies the methane gas to the combustion chamber 130.

  Next, a gaseous fuel combustion control method in the gaseous fuel combustion control system 1 will be described.

After starting the gas engine 11, the throttle opening of the throttle valve 44 is changed according to the amount of depression of the accelerator pedal 441 by the driver. The throttle valve 44 outputs a signal corresponding to the changed throttle opening to the ECU 50. The ECU 50 calculates the supply amount of methane gas necessary for the gas engine 11 to generate a desired rotational torque based on the signal input from the throttle valve 44 as the “supply amount calculation stage” (S101 in FIG. 3).
Further, the ECU 50 determines the amount of air that forms an air-fuel mixture suitable for lean combustion in which the average equivalence ratio of the air-fuel mixture of methane gas and air in the combustion chamber 130 is 1.0 or less based on the calculated supply amount of methane gas. The amount is calculated (S101 in FIG. 3). The ECU 50 outputs a signal corresponding to the calculated amount of air to the throttle valve 44. The throttle valve 44 adjusts the throttle opening so that the amount of air flowing through the first intake pipe 41 and the second intake pipe 42 becomes the calculated amount of air according to the signal output from the ECU 50.

  Next, the ECU 50 determines the injection pressure of the methane gas injected by the fuel injection valve 31 based on the crank angle detected by the rotation angle sensor 19 and the pressure of the gaseous fuel supply pipe 22 detected by the pressure sensor 24 as the “injection pressure calculation stage”. Is calculated (S102 in FIG. 3). The ECU 50 outputs a signal corresponding to the calculated magnitude of the methane gas injection pressure to the regulator 23 (S103 in FIG. 3). The regulator 23 controls the pressure of methane gas based on the input signal. The pressure of the methane gas adjusted by the regulator 23 is detected by the pressure sensor 24, and a signal corresponding to the detected pressure is output to the ECU 50. In the ECU 50, when the pressure of the methane gas output from the pressure sensor 24 is different from the pressure calculated in S102, the ECU 50 outputs a signal to the regulator 23 so as to further adjust the pressure of the methane gas.

  Next, the ECU 50 calculates an injection time for the fuel injection valve 31 to inject methane gas. The injection amount of the fuel injection valve 31 in one combustion is equal to the product of the injection pressure of methane gas and the injection time of the fuel injection valve 31. Therefore, in the ECU 50, as the “injection time calculation stage”, the injection time of the methane gas in the fuel injection valve 31 based on the already calculated methane gas injection amount (S101 in FIG. 3) and injection pressure (S102 in FIG. 3). Is calculated (S104 in FIG. 3).

Next, the ECU 50 calculates the injection start time of methane gas as the “injection start time calculation step” (S105 in FIG. 3).
FIG. 4 shows the relationship between the injection time and the time and time at which the fuel injection valve 31 injects methane gas. When the load of the gas engine 11 is small, the fuel injection valve 31 starts injection at the crank angle θ2 and ends injection at the crank angle θ3, as shown by the solid line L1. Here, the crank angle θ2 is a crank angle when the piston 12 starts moving from the bottom dead center toward the top dead center and the intake valve 18 is closed. The crank angle θ3 is a crank angle larger than the crank angle θ4 when the mixture of methane gas and air in the combustion chamber 130 starts combustion by the spark plug 16. That is, the fuel injection valve 31 supplies methane gas to the combustion chamber 130 at the initial stage of the compression process in the gas engine 11. In the gaseous fuel combustion control system 1 according to the first embodiment, the crank angle when the piston 12 is at the top dead center is 0 ° (BTDC 0 °), and the crank angle when the piston 12 is at the bottom dead center is 180 ° (BTDC 180 °). ).
When the load of the gas engine 11 is large, as shown by the dotted line L2, the fuel injection valve 31 is operated when the compression stroke in the gas engine 11 starts, that is, when the piston 12 is at the bottom dead center. The valve is opened at an angle θ1, that is, BTDC 180 °. Thereby, more methane gas is supplied to the combustion chamber 130 than the injection of the fuel injection valve 31 when the load of the gas engine 11 shown by the solid line L1 is small.

Next, the ECU 50 outputs a signal in accordance with the injection start time of the fuel injection valve 31 calculated based on the crank angle detected by the rotation angle sensor 19 (S106 in FIG. 3). As a result, the fuel injection valve 31 starts injection of methane gas into the combustion chamber 130. Further, the ECU 50 outputs a signal in accordance with the calculated injection time of the fuel injection valve 31 (S106 in FIG. 3). Thereby, the fuel injection valve 31 stops the injection of methane gas into the combustion chamber 130.
Thus, in the gaseous fuel combustion control system 1, the methane gas is supplied to the combustion chamber 130 based on the injection pressure of methane gas, the injection start time, and the injection time calculated by the ECU 50.

  In the gaseous fuel combustion control system 1 according to the first embodiment, the fuel injection valve 31 starts injection of methane gas at the initial stage of the compression stroke in the gas engine 11. In the combustion chamber 130, the air supplied from the first intake pipe 41 and the second intake pipe 42 and the methane gas supplied from the fuel injection valve 31 are mixed while being compressed. As a result, in the combustion chamber 130, a combustible air-fuel mixture layer containing a large amount of methane gas is formed in the vicinity of the spark plug 16, and the proportion of the methane gas contained in the vicinity of the inner wall 137 of the cylinder block 13 is An air-fuel mixture layer smaller than the proportion of methane gas contained in is formed. In the gaseous fuel combustion control system 1, a state in which “stratified combustion” can be realized is formed in the combustion chamber 130 in this way. Thus, combustion in the vicinity of the inner wall 137 can be prevented while allowing combustion in the vicinity of the spark plug 16, and methane gas can be efficiently burned.

  The gaseous fuel combustion control system 1 supplies methane gas directly to the combustion chamber 130 based on the injection amount, injection pressure, injection time, and injection start time of the methane gas determined according to the flow shown in FIG. The injection amount of the gaseous fuel can be set according to the type or state and the theoretical air-fuel ratio of the hydrocarbon gas constituting the gaseous fuel to be used. Thereby, the gaseous fuel supplied to the gas engine 11 can be burned efficiently.

  In the gaseous fuel combustion control system 1, methane gas is injected into the combustion chamber 130 by the fuel injection valve 31 before the piston 12 approaches top dead center and the internal pressure of the combustion chamber 130 increases. Thereby, the driving force required when the fuel injection valve 31 is opened can be reduced.

(Second Embodiment)
Next, the gaseous fuel combustion control system by 2nd Embodiment of this invention is demonstrated based on FIG. The second embodiment includes a gaseous fuel supply valve that supplies methane gas to the second intake pipe, and a compressor that supplies air to the gaseous fuel supply pipe that connects the fuel tank and the fuel injection valve. And different. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted. In FIG. 5, the flow of intake and exhaust in the gas engine 11 is indicated by an arrow S.

  In the gaseous fuel combustion control system 2 according to the second embodiment, a compressor 25 and an air supply pipe 26 that supply air to the gaseous fuel supply pipe 22, and a mixture of methane gas and air flowing through the gaseous fuel supply pipe 22 are second intake air. A branch pipe 451 and a gaseous fuel supply valve 45 to be supplied to the pipe 42.

  One end of the air supply pipe 26 is connected to a pressure sensor 24 provided in the gaseous fuel supply pipe 22. The other end of the air supply pipe 26 is connected to the outside. The air supply pipe 26 is provided with a compressor 25 as “air supply means”.

Air flowing from the other end of the air supply pipe 26 to the air supply pipe 26 is boosted to about 1M P a by the compressor 25. The pressurized air is mixed with methane gas whose pressure is adjusted by the regulator 23 in the pressure sensor 24. A mixture of methane gas and air formed in the pressure sensor 24 is supplied to the combustion chamber 130 via the fuel injection valve 31.

  The gaseous fuel supply valve 45 is provided in the second intake pipe 42. The gaseous fuel supply valve 45 is connected to a branch pipe 451 connected to the downstream side of the pressure sensor 24. The gaseous fuel supply valve 45 is electrically connected to the ECU 50.

  A part of the mixture of methane gas and air flowing through the gaseous fuel supply pipe 22 is supplied to the gaseous fuel supply valve 45 through the branch pipe 451. The gaseous fuel supply valve 45 supplies a mixture of methane gas and air to the second intake pipe 42 based on a signal output from the ECU 50. The air flowing from the upstream intake pipe 43 flowing through the second intake pipe 42 downstream of the gaseous fuel supply valve 45 and the mixture of methane gas and air supplied by the gaseous fuel supply valve 45 are supplied to the combustion chamber 130. .

  FIG. 6 shows the relationship between the amount of methane gas supplied from the fuel injection valve 31 or the second intake pipe 42 to the combustion chamber 130 and the state of the gas engine 11. FIG. 6A shows the relationship between the equivalence ratio φ of the mixture of methane gas and air injected by the fuel injection valve 31 into the combustion chamber 130 and the rotational speed of the gas engine 11. FIG. 6B shows the relationship between the amount of methane gas supplied from the second intake pipe 42 to the combustion chamber 130 and the load of the gas engine 11.

  As shown in FIG. 6 (a), when the rotational speed of the gas engine 11 is such that the idling state is maintained, the equivalence ratio φ of the mixture of methane gas and air injected by the fuel injection valve 31 is about 2.0. is there. Further, as the rotational speed of the gas engine 11 increases, the equivalent ratio φ becomes larger than 2.0. That is, the ratio of methane gas contained in the mixture of methane gas and air injected by the fuel injection valve 31 is increased.

  As shown in FIG. 6B, when the load of the gas engine 11 is minimum, the amount of methane gas supplied by the second intake pipe 42 is minimum. When the load of the gas engine 11 is increased, the amount of methane gas supplied from the fuel injection valve 31 to the combustion chamber 130 is relatively reduced, so that the amount of methane gas supplied by the second intake pipe 42 is increased. At this time, the proportion of methane gas contained in the mixture of methane gas and air supplied by the second intake pipe 42 is smaller than the proportion of methane gas contained in the mixture of methane gas and air injected by the fuel injection valve 31. .

  In the gaseous fuel combustion control system 2 according to the second embodiment, the fuel injection valve 31 supplies an air-fuel mixture with an equivalence ratio φ = 2.0 or more to the combustion chamber 130, while the second intake pipe 42 mixes methane gas and air. Qi is supplied to the combustion chamber 130. Thus, the air-fuel mixture in the vicinity of the spark plug 16 of the combustion chamber 130 is controlled so that the equivalence ratio φ is about 2 to 3, while the air-fuel mixture in the vicinity of the inner wall 137 of the cylinder block 13 has the maximum equivalence ratio φ. Is controlled to be about 0.2. Thereby, in the gaseous fuel combustion control system 2 by 2nd Embodiment, there exists the same effect as 1st Embodiment.

Further, in the gaseous fuel combustion control system 2, since methane gas is supplied to the pressure sensor 24 and the second intake pipe 42 , the time for mixing methane gas and air becomes longer than that in the first embodiment. Thereby, in gaseous fuel combustion control system 2, methane gas and air can fully be mixed and methane gas can be burned more efficiently compared with gaseous fuel combustion control system 1 by a 1st embodiment.

  Further, the second intake pipe 42 of the gaseous fuel combustion control system 2 according to the second embodiment is configured so that the second intake pipe 42 determines the amount of methane gas injected by the fuel injection valve 31 that is relatively smaller than that of the first embodiment. It supplies to the combustion chamber 130 so that it may supplement. Thereby, the mixture of methane gas and air in the combustion chamber 130 can contain methane gas sufficient for combustion.

(Third embodiment)
Next, the gaseous fuel combustion control system by 3rd Embodiment of this invention is demonstrated based on FIGS. The third embodiment differs from the first embodiment in the shape of the piston. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 1st Embodiment, and description is abbreviate | omitted. 7-9, the area | region where the methane gas which the fuel injection valve 31 injects into the combustion chamber 130 diffuses is shown with the dotted line A. FIG. Further, the main flow of methane gas in the region surrounded by the dotted line A is indicated by an arrow F.

In the gaseous fuel combustion control system according to the third embodiment, the substantially center of the end surface forming the combustion chamber 130 of the piston 12 is formed in a concave shape. Specifically, as shown in FIG. 7, an annular recess 121 is provided on the end surface 120 that forms the combustion chamber 130 of the piston 12. The side wall 122 of the recess 121 is formed in a tapered shape.
A convex portion 124 is formed at the center of the concave portion 121 so as to rise from the bottom surface 123 of the concave portion 121 toward the fuel injection valve 31. The side wall 125 of the convex part 124 is formed in a taper shape.

In the gaseous fuel combustion control system according to the third embodiment, when the piston 12 starts moving from the bottom dead center toward the top dead center, the fuel injection valve 31 injects methane gas into the combustion chamber 130 (see FIG. 7). Since the fuel injection valve 31 is an open valve, the methane gas injected from the fuel injection valve 31 spreads in an umbrella shape in the combustion chamber 130 as shown in FIG. The methane gas spreading in an umbrella shape is directed from the radially outward direction to the radially inward direction of the piston 12 by the side wall 122, the bottom surface 123, and the side wall 125 of the convex portion 124 from the bottom dead center toward the top dead center. (See FIG. 8).
When the piston 12 further moves toward the top dead center, the methane gas further flows from the radially outward direction to the radially inward direction of the piston 12, and the methane gas injected by the fuel injection valve 31 is in the vicinity of the ignition plug 16 of the combustion chamber 130. get together. (See Figure 9)

  In the gaseous fuel combustion control system according to the third embodiment, the methane gas injected by the fuel injection valve 31 that is an externally opened valve is collected in the vicinity of the spark plug 16 by the shape of the end face 120 of the piston 12. Thereby, the air-fuel mixture layer exceeding the flammability limit can be formed in the vicinity of the spark plug 16. Therefore, the gaseous fuel combustion system by 3rd Embodiment has the same effect as 1st Embodiment.

  In the gaseous fuel combustion control system according to the third embodiment, the vertical vortex in the direction in which the piston 12 moves is formed in the region near the spark plug 16 using the concave portion 121 and the convex portion 124 of the piston 12. Thereby, mixing of methane gas and air is accelerated | stimulated, and the methane gas of the ignition plug 16 vicinity can be burned more efficiently.

(Fourth embodiment)
Next, the gaseous fuel combustion control system by 4th Embodiment of this invention is demonstrated based on FIG. The fourth embodiment differs from the second embodiment in that a flow control valve is provided in the second intake pipe. In addition, the same code | symbol is attached | subjected to the site | part substantially the same as 2nd Embodiment, and description is abbreviate | omitted. In FIG. 10, the flow of intake and exhaust in the gas engine 11 is indicated by an arrow S.

  In the gaseous fuel combustion control system 4 according to the fourth embodiment, the flow rate control valve 46 is provided in the second intake pipe 42. The flow control valve 46 is provided downstream of the gaseous fuel supply valve 45 in the second intake pipe 42, that is, on the second intake port 132 side. The flow control valve 46 is electrically connected to the ECU 50.

  The flow control valve 46 controls the flow rate of the mixture of methane gas and air flowing through the second intake pipe 42 based on a signal output from the ECU 50. As a result, the balance between the amount of air flowing through the first intake pipe 41 and the amount of air-fuel mixture flowing through the second intake pipe 42 is changed.

  In the gaseous fuel combustion control system 4 according to the fourth embodiment, the flow rate of the second intake pipe 42 that forms a tumble flow in the combustion chamber 130 is controlled by the flow rate control valve 46. The balance between the amount of air flowing through the first intake pipe 41 forming the swirl flow in the combustion chamber 130 and the amount of air-fuel mixture flowing through the second intake pipe 42 forming the tumble flow in the combustion chamber 130 is changed. Thereby, the degree of stratification of the combustion chamber 130 can be adjusted. Therefore, the gaseous fuel combustion control system 4 according to the fourth embodiment can achieve the same effects as the first embodiment.

(Other embodiments)
(A) In the above-described embodiment, the gaseous fuel is methane gas. However, the kind of gaseous fuel is not limited to this. Any gaseous substance that can be supplied to the combustion chamber and combusted may be used.

  (A) In the above-described embodiment, the fuel injection valve is closed at a crank angle larger than the crank angle when the air-fuel mixture in the combustion chamber starts ignition combustion by the spark plug. At this time, the crank angle at which the fuel injection valve closes is preferably larger than BTDC 60 °.

  (C) In the above-described embodiment, the time when the fuel injection valve starts to inject methane gas into the combustion chamber and the injection time have been described as shown in FIG. However, the timing at which the fuel injection valve injects methane gas is not limited to this.

  (D) In the above-described embodiment, the fuel injection valve is an open valve that opens to the outside of the injection hole. However, the type of fuel injection valve is not limited to this. An inner valve that opens a needle inside the nozzle hole may be used.

  (E) In the above-described embodiment, the fuel injection valve injects methane gas along the direction in which the piston moves. However, the direction in which the fuel injection valve injects gaseous fuel is not limited to this.

  (F) In the above-described embodiment, the first intake pipe supplies air to the combustion chamber. However, the gas supplied to the combustion chamber by the first intake pipe is not limited to this. The exhaust gas flowing through the exhaust pipe may be returned to the first intake pipe, and an air-fuel mixture may be supplied to the combustion chamber.

  (G) In the first embodiment and the third embodiment, the second intake pipe supplies air to the combustion chamber. In the second embodiment and the fourth embodiment, the second intake pipe supplies a mixture of methane gas and air to the combustion chamber. However, the gas supplied to the combustion chamber by the second intake pipe is not limited to this. The exhaust gas flowing through the exhaust pipe may be recirculated to the second intake pipe, and a mixture of air and exhaust or a mixture of methane gas, air and exhaust may be supplied to the combustion chamber.

  (H) In the second embodiment, the air supply pipe is connected to the pressure sensor. However, the position where the air supply pipe is connected is not limited to this. You may connect to a gaseous fuel supply pipe so that the air-fuel mixture of air and methane gas can be injected from a fuel injection valve.

  As mentioned above, this invention is not limited to such embodiment, It can implement with the various form of the range which does not deviate from the summary.

1, 2, 4 ... Gaseous fuel combustion control system,
11 ... Engine (internal combustion engine),
19... Rotation angle sensor (crank angle detection means)
21 ... Fuel tank,
23 ・ ・ ・ Regulator (pressure adjusting means),
24 ... Pressure sensor (pressure detection means),
31 ... Fuel injection valve,
41... First intake pipe,
42 ... the second intake pipe,
50 ... ECU (control means),
130 ... combustion chamber,
131 ・ ・ ・ first intake port (one intake port),
132: second intake port (the other intake port).

Claims (9)

A gaseous fuel combustion control system (2) for controlling combustion of gaseous fuel in an internal combustion engine,
Two intake ports (131, 132), exhaust ports (135, 136), and a combustion chamber to which a mixture of gaseous fuel and air or a mixture of gaseous fuel, air and exhaust passing through the exhaust port is supplied The internal combustion engine (11) forming (130);
A fuel tank (21) for storing gaseous fuel supplied to the combustion chamber ;
Before SL is connected to one of the intake ports of an internal combustion engine (131), the first intake pipe for supplying the gas mixture and the exhaust air or air to form a swirl flow in the combustion chamber (41),
An air or gas fuel / air mixture or air / exhaust gas mixture or gas fuel / air connected to the other intake port (132) of the internal combustion engine and forming a tumble flow in the combustion chamber A second intake pipe (42) for supplying an air-fuel mixture with the exhaust;
When the air or air-fuel mixture supplied to the combustion chamber is compressed by the first intake pipe and the second air intake pipe, gaseous fuel or a mixture of gaseous fuel and air is directly injected into the combustion chamber. A fuel injection valve (31);
Air supply means (25) for supplying air to the fuel injection valve;
Pressure adjusting means (23) capable of adjusting the pressure of gaseous fuel supplied to the combustion chamber by the fuel tank to a pressure when the fuel injection valve injects the combustion chamber;
Pressure detecting means (24) for detecting the pressure of the gaseous fuel supplied to the fuel injection valve and outputting a signal corresponding to the detected magnitude of the pressure of the gaseous fuel;
Crank angle detecting means (19) for detecting a crank angle of the internal combustion engine and outputting a signal corresponding to the detected crank angle;
Control means (50) for controlling the pressure, injection time, and injection start time of the gaseous fuel injected by the fuel injection valve based on signals output from the pressure detection means and the crank angle detection means;
With
The ratio of the gaseous fuel contained in the gaseous fuel or the gaseous fuel / air mixture injected by the fuel injection valve is the gas contained in the air or air-fuel mixture supplied to the combustion chamber by the second intake pipe. Gaseous fuel combustion control system, characterized in that it is greater than the proportion of fuel.   The pressure adjusting means can adjust the pressure of the gaseous fuel supplied to the combustion chamber by the fuel tank to the pressure when the fuel injection valve injects the combustion chamber according to the rotational speed of the internal combustion engine. The gaseous fuel combustion control system according to claim 1.   A gaseous fuel combustion control system (1, 2, 4) for controlling combustion of gaseous fuel in an internal combustion engine,
  Two intake ports (131, 132), exhaust ports (135, 136), and a combustion chamber to which a mixture of gaseous fuel and air or a mixture of gaseous fuel, air and exhaust passing through the exhaust port is supplied The internal combustion engine (11) forming (130);
  A fuel tank (21) for storing gaseous fuel supplied to the combustion chamber;
  A first intake pipe (41) connected to one intake port (131) of the internal combustion engine and supplying air or a mixture of air and the exhaust to form a swirl flow in the combustion chamber;
  An air or gas fuel / air mixture or air / exhaust gas mixture or gas fuel / air connected to the other intake port (132) of the internal combustion engine and forming a tumble flow in the combustion chamber A second intake pipe (42) for supplying an air-fuel mixture with the exhaust;
  When the air or air-fuel mixture supplied to the combustion chamber is compressed by the first intake pipe and the second air intake pipe, gaseous fuel or a mixture of gaseous fuel and air is directly injected into the combustion chamber. A fuel injection valve (31);
  Pressure adjusting means (23) capable of adjusting the pressure of the gaseous fuel supplied to the combustion chamber by the fuel tank to the pressure when the fuel injection valve injects the combustion chamber according to the rotational speed of the internal combustion engine;
  Pressure detecting means (24) for detecting the pressure of the gaseous fuel supplied to the fuel injection valve and outputting a signal corresponding to the detected magnitude of the pressure of the gaseous fuel;
  Crank angle detecting means (19) for detecting a crank angle of the internal combustion engine and outputting a signal corresponding to the detected crank angle;
  Control means (50) for controlling the pressure, injection time, and injection start time of the gaseous fuel injected by the fuel injection valve based on signals output from the pressure detection means and the crank angle detection means;
  With
  The ratio of the gaseous fuel contained in the gaseous fuel or the gaseous fuel / air mixture injected by the fuel injection valve is the gas contained in the air or air-fuel mixture supplied to the combustion chamber by the second intake pipe. Gaseous fuel combustion control system, characterized in that it is greater than the proportion of fuel. The fuel injection valve, said after engine intake valve (18) is closed, any one of claims 1-3, characterized by injecting the mixture of the gaseous fuel or gaseous fuel and air The gaseous fuel combustion control system described in 1. The fuel injection valve, one of the claims 1-4, characterized in that the piston of the internal combustion engine (12) to inject the mixture of the gaseous fuel or gaseous fuel and air along the direction of movement The gaseous fuel combustion control system described in 1. The second intake pipe, according to gaseous fuel in the fuel tank to one of claims 1-5, characterized in that it comprises a gas fuel supply valve (45) supplied to the second intake pipe Gaseous fuel combustion control system. The second intake pipe, according to claim characterized in that it comprises a flow control valve for controlling the flow rate of the mixture containing the air or air flowing through the second intake pipe downstream of the gas fuel supply valve (46) 6 The gaseous fuel combustion control system described in 1. The piston of the internal combustion engine, more of claims 1-7, characterized in that the end face of the fuel injection valve side (120) has a projection (124) formed in a convex shape toward the fuel injection valve A gaseous fuel combustion control system according to claim 1. Two intake ports (131, 132), exhaust ports (135, 136), and a combustion chamber to which a mixture of gaseous fuel and air or a mixture of gaseous fuel, air and exhaust passing through the exhaust port is supplied An internal combustion engine (11) forming (130);
A fuel tank (21) for storing gaseous fuel supplied to the internal combustion engine;
A first intake pipe (41) connected to one intake port (131) of the internal combustion engine and supplying air or a mixture of air and the exhaust to form a swirl flow in the combustion chamber;
An air or gas fuel / air mixture or air / exhaust gas mixture or gas fuel / air connected to the other intake port (132) of the internal combustion engine and forming a tumble flow in the combustion chamber A second intake pipe (42) for supplying an air-fuel mixture with the exhaust;
When the air or air-fuel mixture supplied to the combustion chamber is compressed by the first intake pipe and the second air intake pipe, gaseous fuel or a mixture of gaseous fuel and air is directly injected into the combustion chamber. A fuel injection valve (31);
Pressure adjusting means (23) capable of adjusting the pressure of gaseous fuel supplied to the combustion chamber by the fuel tank to a pressure when the fuel injection valve injects the combustion chamber;
Pressure detecting means (24) for detecting the pressure of the gaseous fuel supplied to the fuel injection valve and outputting a signal corresponding to the detected magnitude of the pressure of the gaseous fuel;
Crank angle detecting means (19) for detecting a crank angle of the internal combustion engine and outputting a signal corresponding to the detected crank angle;
Control means (50) for controlling the pressure, injection time, and injection start time of the gaseous fuel injected by the fuel injection valve based on signals output from the pressure detection means and the crank angle detection means;
With
The ratio of the gaseous fuel contained in the gaseous fuel or the gaseous fuel / air mixture injected by the fuel injection valve is the gas contained in the air or air-fuel mixture supplied to the combustion chamber by the second intake pipe. A gaseous fuel combustion control method using a gaseous fuel combustion control system greater than a fuel ratio ,
A supply amount calculating step (S101) for calculating the amount of gaseous fuel supplied to the combustion chamber by the fuel injection valve or the fuel injection valve and the second intake pipe;
Injection that calculates the pressure of the gaseous fuel supplied to the combustion chamber by the fuel injection valve or the fuel injection valve and the second intake pipe based on signals output from the pressure detection means and the crank angle detection means A pressure calculation step (S102);
An injection time calculating step (S104) for calculating an injection time of the fuel injection valve;
An injection start time calculating step (S105) for calculating an injection start time of the fuel injection valve;
A gaseous fuel combustion control method comprising:

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