JP2003262139A - Method and device for controlling air-fuel ratio of gas engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for controlling an air-fuel ratio of a gas engine with high responsiveness even against an abnormal condition such as misfire of the engine or rapid load input at the operation of a multi- cylinder gas engine, capable of preventing combustion at a dense mixture ratio of excess fuel, knocking due to increase of combustion temperature accompanied with the excess fuel, and deterioration of engine output due to excessively lean combustion, while always maintaining the desired air-fuel ratio. <P>SOLUTION: This gas engine is structured in a manner that mixture gas formed by injecting gas fuel in supply air flowing in an air supply passage is supplied to a combustion chamber for combustion. A required volume of air is calculated based on a detected value of fuel flow rate in the fuel supply passage, and an actual volume of air is calculated based on a detected value of supply air pressure and supply air temperature in the air supply passage. The supply air volume in the air supply passage is controlled so that the actual air volume is equal to the required air volume. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber for producing a mixed gas formed by injecting gas fuel introduced from a fuel supply passage into supply air (air) introduced into a fuel injection device from an air supply passage. The present invention relates to an air-fuel ratio control method and apparatus for a multi-cylinder gas engine configured to be supplied to and burned.

[0002]

2. Description of the Related Art Supply air (air) introduced into a fuel injection device from a supply passage connected to a supply outlet of an exhaust turbocharger.
In a gas engine configured to supply a mixed gas formed by injecting the gaseous fuel introduced from the fuel supply passage into the combustion chamber for combustion, The intake air temperature of the engine, that is, the supply air temperature, changes the amount of air supplied to the engine (weight flow rate), which changes the mixture ratio of fuel (gas fuel) and air, that is, the air-fuel ratio, and makes combustion unstable. Tends to be prone to.

Particularly, in a gas engine of a premixed combustion system in which fuel and air are mixed in a fuel injection device and the mixed gas is supplied to a combustion chamber, the fluctuation of the air-fuel ratio has a great influence on combustion, and the ambient temperature In the summer when the temperature is high, the amount of air supplied to the engine (weight flow rate) decreases and the engine runs with excess fuel, which easily causes knocking. In winter when the atmospheric temperature is low, the amount of air supply (weight flow rate) increases. Becomes larger, the operation is performed in a fuel-lean state, and a misfire easily occurs. As a means for coping with such a problem, in a stationary power generation gas engine or the like, an air-fuel ratio that controls the intake air temperature (supply air temperature) of the engine to be constant without being affected by the outside air temperature (atmosphere temperature). A control method is used.

FIG. 7 shows an example of an air-fuel ratio control device in such a stationary power generation gas engine. In the figure, 10
0 is an engine, 101 is a cylinder of the engine 100 (in this example, the case of four cylinders is shown), 103 is a generator driven by the engine 100, 104 is an exhaust turbocharger (hereinafter referred to as supercharger), 104a is a turbine of the supercharger 104, and 104b is a compressor. 1
Reference numeral 05 denotes the exhaust outlet of each cylinder 101 and the turbine 10
An exhaust passage connecting the exhaust inlet 4a. Reference numeral 107 denotes an air supply passage that connects the air supply (air) outlet of the compressor 104b and each cylinder 101, and branches in the middle to be connected to each cylinder 101. Further, the air supply passage 10
An air cooler 106 for cooling the supply air from the outlet of the compressor 104b is provided in the middle of 7.

Reference numeral 102 denotes a fuel injection device arranged for each cylinder 101 on the inlet side of each cylinder 101 of the air supply passage 107. Reference numeral 109 denotes a fuel supply main pipe from a gas fuel (hereinafter referred to as fuel) supply source (not shown). , 108 are fuel supply pipes branched from the fuel supply main pipe 109 for each cylinder 101 and connected to the respective fuel injection devices 102. Reference numeral 9 is a fuel supply amount adjusting valve for opening and closing each of the fuel supply pipes 109 and adjusting the opening thereof.

Reference numeral 20 denotes the turbine 10 in the exhaust passage 105.
4a is an exhaust bypass passage branched from the inlet front portion and bypassing the turbine 104a and connected to the exhaust outlet pipe 110 at the outlet of the turbine 104a.
At 0, an exhaust bypass amount adjusting valve 21 that opens and closes this and controls the passage area thereof is installed. 011
Is an engine output detector for detecting the output of the engine 100, that is, the engine load from the generator 103.
Reference numeral 4 is a supply pressure detector for detecting the pressure of supply air (intake air) in the supply passage 107, and 5 is the supply passage 107.
2 is a supply air temperature detector for detecting the temperature of supply air in.

Reference numeral 010 is a control device, which detects an engine output detection signal from the engine output detector 011 and a supply air pressure detection signal from the supply air pressure detector 4 in the supply air passage 107.
The detection signals of the supply air temperature in the supply air passage 107 are respectively input from the supply air temperature detector 5, and the opening degree of the exhaust bypass amount adjustment valve 21, that is, the passage area of the exhaust bypass passage 20 is calculated based on these detection signals. And outputs it to the exhaust bypass amount adjusting valve 21.

In the air-fuel ratio control system for such a multi-cylinder gas engine, the exhaust gas from the engine 100 drives the turbine 104a of the supercharger 104 through the exhaust passage 105 and is discharged from the exhaust outlet pipe 110 to the outside. The supply air (air) pressurized by the compressor 104b that is coaxially driven by the turbine 104a is the air cooler 106.
Then, the fuel is cooled and cooled and introduced into the fuel injection device 102 of each cylinder through the air supply passage 107. On the other hand, the fuel from the fuel supply main pipe 109 is the fuel supply pipe 1 of each cylinder 101.
It is branched into 08 and introduced into the fuel injection device 102. Then, in the fuel injection device 102, the supply air and the fuel are mixed to form an air-fuel mixture, and each cylinder 10
1, and is used for combustion.

During operation of the gas engine, the engine output detection signal detected by the engine output detector 011 and the air supply passage 1 detected by the air supply pressure detector 4 are detected.
The detection signal of the supply air pressure at 07 and the detection signal of the supply air temperature at the supply air passage 107 detected by the supply air temperature detector 5 are input to the control device 010, respectively. The control device 0
In 10, the actual air amount to the engine 100 (actual air supply amount) is calculated based on the detection signal of the supply air pressure and the detection signal of the supply air temperature, and the engine output based on the detection signal of the engine output. Calculate the required air amount corresponding to the detected value.

In the control device 010, the exhaust bypass amount and the exhaust bypass corresponding to the output of the supercharger such that the amount of air delivered from the supercharger 104, that is, the actual air amount matches the required air amount. The opening degree of the exhaust bypass adjusting valve 21 corresponding to the amount is calculated, and the exhaust bypass adjusting valve 21 is controlled to the opening degree. As a result, the air-fuel ratio of the air-fuel mixture in which the supply air and the fuel are mixed in the fuel injection device 102 becomes an air-fuel ratio adapted to the engine output and is supplied to each cylinder 101 of the engine 100.

Further, in the technique disclosed in US Pat. No. 5,386,698, the exhaust passage from the engine is branched from the front portion of the turbocharger turbine inlet, bypasses the turbine, and is connected to the exhaust outlet pipe of the turbine outlet. An exhaust bypass passage and an exhaust bypass amount adjusting valve that opens and closes the exhaust bypass passage and controls the passage area of the exhaust bypass passage are provided, and the engine speed is detected and input to a control device. The opening degree of the exhaust bypass amount adjusting valve is controlled so that the supply amount corresponds to the number, and the engine is controlled to have an air-fuel ratio suitable for the rotation speed.

[0012]

In a multi-cylinder gas engine, a speed governing device (governor) detects an engine load (engine output) or an engine rotation speed so that the engine load or the engine rotation speed becomes a target value. When the misfire occurs in one of the cylinders by controlling the fuel supply amount to the cylinder, the fuel flow rate (fuel injection amount) of the entire engine until the output of the engine unit or the number of revolutions returns to the state before the misfire by the speed control device. Is increased.

On the other hand, in the prior art shown in FIG. 7, the controller detects the engine load (engine output) and controls the air amount corresponding to the engine load. That is, since the air amount is controlled to the target value by the detection signal of the engine output, the fuel flow rate is increased by the speed governor when the misfire occurs, and the engine output or engine speed before the misfire is maintained. In this case, the amount of air is maintained at the same level as before the misfire, the amount of air is insufficient with respect to the increased fuel injection amount, and combustion occurs at an excess fuel rich mixture ratio that deviates from the proper air-fuel ratio, and the combustion temperature See the occurrence of knocking due to the rise of. Further, in such a conventional technique,
When there is a rapid load application, the air supply amount (intake air amount) via the turbocharger is controlled by the engine output or the engine speed, so the speed governor receives the load application signal. Responsiveness is low during the transition period until the fuel injection amount increases, and excessive lean combustion occurs with excessive air amount, resulting in a reduction in engine output.

In view of the above prior art, the present invention has a high responsiveness to the occurrence of abnormal states such as engine misfire and rapid load application during the operation of a multi-cylinder gas engine, and is always a target. Air-fuel ratio control of a gas engine capable of maintaining the air-fuel ratio and preventing the occurrence of knocking due to combustion at an excessive rich mixture ratio of fuel and the accompanying increase in combustion temperature and the decrease in engine output due to excessive lean combustion It is an object to provide a method and an apparatus thereof.

[0015]

In order to solve the above problems, the present invention provides an invention as set forth in claim 1, in which gas fuel introduced from a fuel supply passage is injected into the supply air (air) flowing through the supply passage. In the air-fuel ratio control method for a gas engine configured to supply the mixed gas formed in the combustion chamber and burn it, the required air amount is calculated based on the detected value of the fuel flow rate in the fuel supply passage. Calculating an actual air amount based on the detected values of the air supply pressure and the air supply temperature in the air supply passage, and controlling the air supply amount in the air supply passage so that the actual air amount matches the required air amount. A method for controlling an air-fuel ratio of a gas engine is proposed.

The invention according to claim 4 relates to the invention of an apparatus for carrying out the invention according to claim 1, in which gas fuel introduced from the fuel supply passage is injected into the supply air (air) flowing through the supply passage. In a gas engine configured to supply the formed mixed gas into a combustion chamber for combustion, a fuel flow rate detector that detects a fuel flow rate in the fuel supply passage, and a pressure of supply air in the supply passage and A supply air pressure detector and a supply air temperature detector for respectively detecting temperatures, and means for calculating a required air amount based on a detected value of the fuel flow rate input from the fuel flow rate detector, and the supply air pressure detector. And means for calculating the actual air amount based on the detected values of the air supply pressure and the air supply temperature input from the air supply temperature detector, and the air supply in the air supply passage so that the actual air amount matches the required air amount. amount Characterized by comprising a control device having a supply air amount control means for controlling.

The invention according to claim 2 is the same as in claim 1,
In controlling the supply air amount, the supply air discharge amount in the supply air discharge means for discharging a part of the supply air in the supply air passage to the outside is controlled so that the actual air amount matches the required air amount. It is characterized by

A fifth aspect of the present invention relates to an apparatus for carrying out the invention of the second aspect, and in the fourth aspect, the air supply discharge passage branched from the air supply passage and communicating with the outside and the air supply passage. An air supply release valve provided in the air supply passage for controlling the amount of air supplied from the air supply passage is provided, and the air supply amount control means of the control device ensures that the actual air amount matches the required air amount. It is characterized in that the supply air release valve is controlled to an opening degree corresponding to a large supply air discharge amount.

According to a third aspect of the present invention, in the first aspect,
An exhaust gas turbocharger having an air supply outlet connected to the air supply passage, and an exhaust gas bypass amount adjusting means for controlling an exhaust gas bypass amount in an exhaust gas bypass passage communicating with the outside by bypassing a turbine of the turbocharger. At the same time, in controlling the supply air amount, the exhaust bypass amount is controlled via the exhaust bypass amount adjusting means to an amount corresponding to the supply air adjustment amount such that the actual air amount matches the required air amount. Is characterized by.

The invention according to claim 6 relates to the invention for an apparatus for carrying out the invention according to claim 3, and in claim 4, the exhaust gas turbocharger having an air supply outlet connected to the air supply passage and the gas. An exhaust bypass passage communicating with the outside of the exhaust turbocharger by bypassing the turbine of the exhaust turbocharger from an exhaust passage of the engine, and an exhaust bypass amount adjusting valve provided in the exhaust bypass passage for controlling the exhaust bypass amount are provided. The supply air amount control means of the control device calculates an exhaust bypass amount corresponding to the supply air adjustment amount such that the actual air amount matches the required air amount, and sets the exhaust bypass amount to an opening corresponding to the exhaust bypass amount. It is characterized in that it is configured to control the regulating valve.

According to this invention, the detected values of the supply pressure and the supply temperature are input to the control device from the supply pressure detector and the supply temperature detector, and the detected value of the fuel flow rate is controlled from the fuel flow rate detector. The actual air amount of the gas engine is calculated based on the detected values of the supply air pressure and the supply air temperature in the control device. Further, the control device calculates the required air amount under the operating condition (engine output) based on the detected value of the fuel flow rate and the reference air-fuel ratio preset for the engine output (engine load).

In the control device, the actual air amount and the required air amount are compared to calculate the air amount deviation,
Required air amount (target air amount) calculated by the air supply amount control means so that the air amount deviation becomes 0 (zero), that is, the actual air amount is calculated based on the detected value of the fuel flow rate and the reference air-fuel ratio.
It is possible to control the amount of air supply in the air supply passage so that

The control of the air supply amount by the air supply amount control means is specifically configured as described in claims 2, 5 and 3, 6. According to the present invention, the opening degree of the air supply discharge valve provided in the air supply discharge passage branched from the air supply passage and communicated with the outside is controlled by the air supply amount control means of the control device. The opening amount calculated by the above is adjusted, and the amount of supply air through the supply air passage is controlled so that the actual amount of air in the supply passage matches the required amount of air.

According to the third and sixth aspects of the invention, the exhaust bypass amount of the exhaust bypass amount adjusting means for controlling the exhaust bypass amount in the exhaust bypass passage communicating with the outside by bypassing the turbine of the supercharger is set. Corresponds to a supply air adjustment amount such that the exhaust air bypass amount calculated by the supply air amount control means of the control device, that is, the actual air amount sent from the compressor of the supercharger to the air supply passage matches the required air amount. It becomes possible to control the quantity.

Therefore, according to this invention, the fuel flow rate is detected and calculated based on the detected value of the fuel flow rate and the reference air-fuel ratio preset for the operating conditions (engine output, engine load) of the gas engine. Since the air supply amount in the air supply passage is controlled so that the actual air amount in the air supply passage matches the required air amount, the actual air amount corresponds to the engine operating conditions even if there is a sudden change in the fuel flow rate. The required air amount based on the air-fuel ratio can be matched without causing a delay.

Therefore, even if a misfire occurs in one of the cylinders, the actual air amount in the air supply passage can be made to match the required air amount based on the fuel flow rate and the preset reference air-fuel ratio. Even if the fuel injection amount is increased by the control of the speed governor, the air amount is increased in accordance with the increase in the fuel injection amount, and it is possible to avoid generating an excessive fuel rich mixture that deviates from the proper air-fuel ratio. Therefore, the engine can be operated with an appropriate air-fuel ratio without being affected by misfire, and knocking due to an increase in combustion temperature can be prevented.

Further, even when the load is rapidly applied, it becomes possible to match the actual air amount to the fuel flow rate and the required air amount based on the preset reference air-fuel ratio without delay, and the transient period In, it is possible to change the actual air amount by quickly following the fuel injection amount,
It is possible to avoid the reduction in engine output due to excessive lean combustion due to the low response during the transient period as in the conventional technique.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless there is a specific description, and are merely illustrative examples. Nothing more.

FIG. 1 is an overall configuration diagram of an air-fuel ratio control device for a multi-cylinder gas engine according to a first embodiment of the present invention, FIG. 2 is a control block diagram of the air-fuel ratio control device, and FIG. 3 is a calculation of an actual air amount. Diagram, FIG. 4 is a setting diagram of the excess air ratio, and FIG. 5 is an explanatory diagram of the action when a misfire occurs. FIG. 6 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

In FIG. 1 showing the first embodiment, 100 is an engine, 101 is a cylinder of the engine 100 (in this example, four cylinders are shown), and 103 is a generator driven by the engine 100. Reference numeral 104 denotes an exhaust turbo supercharger (hereinafter referred to as a supercharger), which is the cylinder 10
A turbine 104a driven by exhaust gas introduced from an exhaust port 1 through an exhaust passage 105 and a compressor 10 for air compression coaxial with the turbine 104a.
4b is a known one. 110 is the turbine 10
4a is an exhaust outlet pipe connected to the exhaust outlet of 4a. 107
Is an air supply passage connecting the air supply (air) outlet of the compressor 104b of the supercharger 104 and each cylinder 101, and is branched and connected to each cylinder 101 on the way. In the middle of the air supply passage 107, the compressor 1
An air cooler 106 for cooling the supply air from the 04b outlet is provided.

Reference numeral 102 denotes a fuel injection device arranged for each cylinder 101 on the inlet side of each cylinder 101 of the air supply passage 107, and 109 denotes a fuel supply main pipe from a gas fuel (hereinafter referred to as fuel) supply source (not shown). , 108 are fuel supply pipes branched from the fuel supply main pipe 109 for each cylinder 101 and connected to the respective fuel injection devices 102. Reference numeral 9 is a fuel supply amount adjusting valve for opening and closing each of the fuel supply pipes 109 and adjusting the opening thereof. The above configuration is similar to that of the conventional technique shown in FIG.

Reference numeral 1 is a fuel flow rate detector for detecting the fuel flow rate of the gas fuel in the fuel supply main pipe 109, that is, the fuel injection amount, 2 is a fuel pressure detector for detecting the fuel pressure of the gas fuel, and 3 is the gas fuel. A fuel temperature detector 10 for detecting the fuel temperature is a control device for carrying out calculation and control which will be described later. The fuel flow rate detector 1 detects the fuel flow rate and the fuel pressure detector 2 detects the fuel pressure. , And the detected value of the fuel temperature from the fuel temperature detector 3 are input to the control device 10, respectively. Further, 4 is a supply air pressure detector that detects the pressure of the supply air (intake air) in the supply air passage 107, and 5 is a supply air temperature detector that detects the temperature of the supply air in the supply air passage 107, The detected value of the supply air pressure from the supply air pressure detector 4 and the detected value of the supply air temperature from the supply air temperature detector 5 are input to the control device 10, respectively.

Reference numeral 7 is a supply air discharge pipe branched from the supply air passage 107 and communicated with the outside, and reference numeral 6 is provided in the supply air discharge pipe 7, and the supply air from the supply air passage 107 is provided by a method described later. It is a charge air release valve that controls the release amount. Reference numeral 11 denotes a supply air discharge opening detector that detects the opening of the supply air discharge valve and inputs it to the control device 10.

In the air-fuel ratio control system for a multi-cylinder gas engine having such a configuration, the exhaust gas from the engine 100 passes through the exhaust passage 105 and the turbine 10 of the supercharger 104.
4a is driven and discharged from the exhaust outlet pipe 110 to the outside. The supply air (air) pressurized by the compressor 104b that is coaxially driven by the turbine 104a is cooled and cooled by the air cooler 106 and introduced into the fuel injection device 102 of each cylinder 101 through the supply passage 107. To be done.
On the other hand, the fuel from the main fuel supply pipe 109 is branched into the fuel supply pipe 108 of each cylinder and introduced into the fuel injection device 102. Then, in the fuel injection device 102, the supply air and the fuel are mixed to form an air-fuel mixture, which is supplied to each cylinder 101 and used for combustion.

Next, the operation of the air-fuel ratio control system for a multi-cylinder gas engine having such a configuration will be described. In FIG. 2 showing a control block diagram, the detected value of the fuel flow rate (m3 / hr) from the fuel flow rate detector 1, the detected value of the fuel pressure from the fuel pressure detector 2, and the detected value from the fuel temperature detector 3 The detected value of the fuel temperature is input to the fuel consumption amount calculation unit 32 of the control device 10. In fuel consumption calculating section 32, the fuel flow rate (m3 / hr), the fuel consumption for obtaining the necessary amount of air from the fuel pressure and fuel temperature Q _{c (Nm}
³ / hr) is calculated and input to the required air amount calculation unit 33.

The required air amount calculation unit 33 calculates the required air amount Q _re corresponding to the fuel consumption amount Q _c (Nm ³ / hr) by the following equation (1) using the fuel consumption amount Q _c. To do. Q _re = a · λ · Q _c (1) where λ is the excess air ratio at the engine output (engine load) L, and as shown in FIG.
With respect to the appropriate value of the excess air ratio λ is preset. In the figure, the excess air ratio λ is 40% of the total output.
%, The output Lm decreases in proportion to the engine output L, and when it exceeds the output Lm, it becomes a constant value λm. Also,
a is an adjustment coefficient, and the air-fuel ratio ε is ε∝a · λ (2).

Therefore, according to the above equations (1) and (2), Q _re ∝ε · Q _c (3) Therefore, using the detected value of the fuel consumption amount Q _c (Nm ³ / hr), the engine output (engine Load) L by calculating the required air amount Q _re from the set value of the excess air ratio λ by the equation (1), the required air amount at the proper air-fuel ratio at the engine output (engine load) L, that is, the reference air-fuel ratio. Q _re can be determined.

The detected value of the supply air pressure from the supply air pressure detector 4 and the detected value of the supply air temperature from the supply air temperature detector 5 are input to the actual air amount calculation unit 31 of the control device 10. It The actual air amount Qs to the engine 100 is expressed as a function of the supply air pressure Ps and the specific gravity Cs of the supply air, as shown in FIG. The specific gravity Cs of the supply air is expressed by the following equation (4) as a function of the supply air pressure Ps and the supply air temperature Ts. C _s = f (P _s · T _s ) (4) Therefore, the specific gravity Cs of the air supply is calculated in (4) from the detected value of the air supply pressure Ps and the detected value of the air supply temperature Ts, and FIG. The actual air amount Qs can be calculated from the relationship diagram between Ps · Cs and the actual air amount Qs.

Calculated by the required air amount calculator 33
Required air amount Q at the standard air-fuel ratio_{r e}And actual air amount calculation
The actual air amount Qs calculated by the unit 31 is the air amount comparison unit 34.
Entered in. In the air amount comparison unit 34, the above-mentioned essential
Air amount deviation between required air amount Qr and actual air amount Qs ΔQ = Q_sr-Q_r Is calculated and input to the supply air release valve opening adjustment amount calculation unit 35.
It In the supply air release valve opening adjustment amount calculation unit 35,
Supply through the supply air release valve 6 corresponding to the air amount deviation ΔQ
Obtain the adjustment value of the air release amount,
A corresponding opening adjustment value of the supply air release valve 6 is calculated.

Reference numeral 11 is a supply air release valve opening detector for detecting the opening of the supply air discharge valve 6, reference numeral 36 is a supply air discharge valve opening calculation unit, and the supply air discharge valve opening calculation unit 36 includes The supply air discharge valve opening adjustment value from the supply air discharge valve opening adjustment amount calculation unit 35 and the supply air discharge valve opening detection value from the supply air discharge valve opening detector 11 are input. The air supply release valve opening calculation unit 36 corrects the air supply release valve opening detection value with the air supply release valve opening adjustment value to calculate a necessary air supply release valve opening, Input to the driving device 37. Then, the supply air release valve driving device 37 drives the supply air release valve 6 to reach the required supply air release valve opening degree.

Therefore, according to such an embodiment, the air supply passage 1
The supply air discharge valve 6 provided in the supply air discharge pipe 7 that branches from 07 and communicates with the outside is adjusted to an opening degree corresponding to the required air amount calculated by the control device 10, and the supply air is discharged. The amount of supply air discharged through the pipe 7 can be controlled so that the actual amount of air in the supply passage 107 matches the required amount of air,
It is possible to control the air supply amount in the air supply passage 107 so that the actual air amount matches the required air amount (target air amount) calculated based on the detected value of the fuel flow rate and the reference air-fuel ratio.

Therefore, according to this embodiment, the fuel flow rate is detected and calculated based on the detected value of the fuel flow rate, the engine output which is the operating condition of the gas engine, and the reference air-fuel ratio preset for the engine load. The air supply passage 10 is adjusted so that the actual air amount in the air supply passage 107 matches the required air amount.
Since the supply air amount in 7 is controlled, it is possible to match the actual air amount with the required air amount based on the air-fuel ratio corresponding to the engine operating conditions without delay even if there is a sudden change in the fuel flow rate. Becomes

Therefore, in the case where a misfire occurs in one of the cylinders 101 of the engine 100, as shown in FIG. 5, the engine output L is temporarily decreased due to the misfire and the engine output constant control is performed. , The fuel flow rate F of the entire engine is increased by ΔF until the engine output L is restored.

However, when the actual air amount in the air supply passage 107 is controlled in accordance with the detected value of the engine output L as in the prior art, as shown in B of FIG. Is temporarily reduced, the engine output L is reduced at the time of the misfire, and the air amount Q is controlled to be reduced by ΔQ. As a result, the air-fuel ratio E decreases by ΔE with respect to the normal state, combustion becomes performed at an excess fuel rich mixture ratio that deviates from the proper air-fuel ratio during the normal state, and knocking due to an increase in the combustion temperature is likely to occur. On the other hand, in such an embodiment of the present invention, as shown in FIG. 5A, the air amount Q is controlled to increase in accordance with the fuel flow rate F according to the detected value of the fuel flow rate F. The air-fuel ratio E is kept constant even during such a misfire.

Therefore, according to this embodiment, the actual air amount in the air supply passage 107 can be made equal to the required air amount based on the fuel flow rate and the preset reference air-fuel ratio. Even if the fuel injection amount is increased, the air amount is increased in accordance with the increase in the fuel injection amount, and it is possible to avoid the generation of an excessive fuel rich mixture that deviates from the proper air-fuel ratio, and to prevent the influence of misfire. The engine can be operated with an appropriate air-fuel ratio without receiving it.

In the second embodiment shown in FIG. 6, 20 is branched from a portion of the exhaust passage 105 in front of the inlet of the turbocharger 104 turbine 104a, bypasses the turbine 104a, and is connected to the exhaust outlet pipe 110 at the outlet of the turbine 104a. The exhaust bypass passage 21 is an exhaust bypass amount adjusting valve 21 for opening and closing the exhaust bypass passage 20 and controlling the passage area thereof. The exhaust bypass amount adjustment valve 21 is
The control device 10 controls the opening degree corresponding to the exhaust bypass amount corresponding to the supply air adjustment amount such that the actual air amount matches the required air amount.

In the second embodiment, the control device 10 calculates the actual air amount and the required air amount in the same manner as in the first embodiment, and outputs the air amount from the supercharger 104, that is, the actual air amount. Calculating the exhaust bypass amount corresponding to the supercharger output such that the amount matches the required air amount and the opening degree of the exhaust bypass adjusting valve 21 corresponding to the exhaust bypass amount,
The exhaust bypass adjusting valve 21 is controlled to the opening degree.

That is, according to the second embodiment, the exhaust bypass of the exhaust bypass amount adjusting valve 21 for controlling the exhaust bypass amount in the exhaust bypass passage 20 that bypasses the turbine 104a of the supercharger 104 and communicates with the outside. Quantity,
Exhaust gas bypass amount calculated by the control device 10, that is, from the compressor 104b of the supercharger 104 to the air supply passage 1
It is possible to control the actual air amount sent to 07 to an amount corresponding to the air supply adjustment amount such that the actual air amount matches the required air amount. The other structure is the same as that of the first embodiment, and the same members as these are denoted by the same reference numerals.

[0049]

As described above, according to the present invention, the fuel flow rate is detected, and the reference air-fuel ratio preset with respect to the detected value of the fuel flow rate and the operating condition (engine output, engine load) of the gas engine. The air supply amount in the air supply passage is controlled so that the actual air amount in the air supply passage matches the required air amount calculated based on It is possible to match the required air amount based on the air-fuel ratio corresponding to the operating condition of 1 above without delay.

Therefore, even if a misfire occurs in one of the cylinders, the actual air amount in the air supply passage can be made to match the required air amount based on the fuel flow rate and the preset reference air-fuel ratio. As described above, it is avoided that the fuel injection amount is increased by the control of the speed governor at the time of misfire and an excess fuel rich mixture that deviates from the proper air-fuel ratio is generated, and the proper air-fuel ratio is maintained without being affected by the misfire. As a result, the engine can be operated and the occurrence of knocking due to an increase in combustion temperature can be prevented.

Further, even when the load is rapidly applied, the actual air amount can be matched with the required air amount based on the fuel flow rate and the preset reference air-fuel ratio without delay, and the transient period In, it is possible to change the actual air amount by quickly following the fuel injection amount,
It is possible to avoid the reduction in engine output due to excessive lean combustion due to the low response during the transient period as in the conventional technique.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an air-fuel ratio control device for a multi-cylinder gas engine according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of the air-fuel ratio control device.

FIG. 3 is a calculation diagram of an actual air amount.

FIG. 4 is a setting diagram of an excess air ratio.

FIG. 5 is an explanatory view of the operation when a misfire occurs.

FIG. 6 is a view corresponding to FIG. 1 and showing a second embodiment of the present invention.

FIG. 7 is a diagram corresponding to FIG. 1 showing a conventional technique.

[Explanation of symbols]

1 Fuel flow rate detector 2 Fuel pressure detector 3 Fuel temperature detector 4 Air supply pressure detector 5 Air supply temperature detector 6 Air supply release valve 7 Air supply discharge pipe 9 Fuel supply adjustment valve 10 Control device 11 Air supply discharge opening detector 20 Exhaust bypass passage 21 Exhaust bypass amount adjustment valve 100 engine 101 cylinder 102 fuel injection device 103 generator 104 Exhaust turbocharger 104a turbine 104b compressor 105 Exhaust passage 106 air cooler 107 Air supply passage 108 Fuel supply pipe 109 Fuel supply main

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 41/04 305 F02D 43/00 301H 43/00 301 301R F02B 37/12 301A F term (reference) 3G005 DA06 EA16 FA04 FA22 GB28 GD11 GE09 HA04 HA05 JA42 JA45 3G065 AA03 AA04 AA09 AA10 BA02 CA11 CA18 DA04 DA15 EA07 FA02 FA12 GA04 GA18 GA19 GA27 3G084 AA03 BA04 BA08 BA09 BA13 CA03 CA04 DA12 DA38 EA05 EA11 EB12 EC01 EC03 FA00 FA01 FA02 FA10 FA13 FA33 3G092 AA05 AA13 AA18 AB06 BA01 BA04 BB01 DB03 DE01S DF01 DG07 EA01 EA02 EB05 EC01 FA05 FA16 GA03 HA00X HA00Z HA04Z HA16Z HB01Z HB03Z HB04Z HE01Z 3G301 HA01 HA06 HA01 HA01 HA01 HA01 HA02 HA01 HA01 HA01 HA02 HA01 HA02 HA01 HA01 HA02 HA01 HA02 HA01 HA01 HA02 HA01 HA02 HA01 HA01 HA01 HA02 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA01 HA02 HA11 HA01 HA01 HA01 HA01 HA01 HA02 HA01 HA02 HAZ

Claims (6)

[Claims] 1. An empty space of a gas engine configured to supply a mixed gas formed by injecting a gas fuel introduced from a fuel supply passage into a combustion chamber to burn the air while the air is flowing through the supply passage. In the fuel ratio control method, the required air amount is calculated based on the detected value of the fuel flow rate in the fuel supply passage, and the actual air amount is calculated based on the detected values of the air supply pressure and the air supply temperature in the air supply passage, An air-fuel ratio control method for a gas engine, wherein the air supply amount in the air supply passage is controlled so that the actual air amount matches the required air amount. 2. In controlling the supply air amount, the supply air discharge amount in a supply air discharge means for discharging a part of the supply air in the supply air passage to the outside is set so that the actual air amount matches the required air amount. The air-fuel ratio control method for a gas engine according to claim 1, wherein the control is performed as follows. 3. An exhaust bypass for controlling an amount of exhaust bypass in an exhaust turbo supercharger whose supply air outlet is connected to the supply air passage and an exhaust bypass passage communicating with the outside by bypassing a turbine of the supercharger. In addition to providing an amount adjusting means, in controlling the air supply amount, the exhaust bypass amount via the exhaust bypass amount adjusting means corresponds to the air supply adjusting amount such that the actual air amount matches the required air amount. The air-fuel ratio control method for a gas engine according to claim 1, wherein the air-fuel ratio is controlled to an amount. 4. A gas engine configured to supply a mixed gas formed by injecting a gas fuel introduced from a fuel supply passage into the combustion chamber during combustion while supplying air flowing through the supply passage, to burn the gas. The fuel flow rate detector for detecting the fuel flow rate in the fuel supply passage, the supply air pressure detector and the supply air temperature detector for detecting the pressure and temperature of the supply air in the supply passage, respectively, and the fuel flow rate A means for calculating the required air amount based on the detected value of the fuel flow rate input from the detector, and an actual means based on the detected values of the supply air pressure and the supply air temperature input from the supply air pressure detector and the supply air temperature detector. A gas engine, comprising: a control device having means for calculating an air amount and air supply amount control means for controlling the air supply amount in the air supply passage so that the actual air amount matches the required air amount. Engine air-fuel ratio control device. 5. A charge air discharge passage branched from the charge air passage and communicating with the outside, and a charge air discharge valve provided in the charge air discharge passage for controlling the amount of charge air discharged from the charge air passage. And the air supply amount control means of the control device is configured to control the air supply release valve to an opening degree corresponding to the supply air release amount such that the actual air amount matches the required air amount. The air-fuel ratio controller for a gas engine according to claim 4. 6. An exhaust gas turbocharger whose air supply outlet is connected to the air supply passage, and an exhaust gas bypass passage that communicates with the exhaust passage of the gas engine by bypassing the turbine of the exhaust gas turbocharger and communicating with the outside. And an exhaust bypass amount adjusting valve provided in the exhaust bypass passage for controlling the exhaust bypass amount, and the supply air amount control means of the control device adjusts the supply air so that the actual air amount matches the required air amount. 5. The air-fuel ratio of the gas engine according to claim 4, wherein the exhaust gas bypass amount adjusting valve is configured to calculate an exhaust gas bypass amount corresponding to the amount and control the exhaust gas bypass amount adjusting valve to an opening degree corresponding to the exhaust gas bypass amount. Control device.