JP2012132419A - Apparatus and method for detecting failure of fuel supply valve in gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and method for detecting a failure of a fuel supply valve supplying through injection gaseous fuel during air supply in a gas engine, and especially, a failure detection apparatus and method of the fuel supply valve in the gas engine, which can detect gas leakage during a valve closing period, generated during operation in the fuel supply valve.SOLUTION: The failure detection apparatus includes: an oxygen concentration sensor 51 arranged in an air supply port 13; and a failure transmitter determining, with an oxygen concentration signal of the oxygen concentration sensor 51 inputted thereto, the fuel supply valve 26 to be abnormal, and outputting a failure signal, when an oxygen concentration of the gas supply port 13 is lower than a predetermined threshold.

Description

  The present invention relates to an apparatus and a method for detecting an abnormality of a fuel supply valve that injects and supplies gaseous fuel during supply in a gas engine, and in particular, to detect a gas leak when the fuel supply valve is closed during operation. The present invention relates to an abnormality detection apparatus and method capable of performing the above.

Gas engines that use gaseous fuels such as compressed natural gas, liquefied propane gas, and compressed hydrogen attract great attention as high-efficiency, clean engines that can be used not only for power supply but also for cogeneration facilities that use exhaust heat. Collecting.
In general, a gas engine having multiple cylinders is provided for each engine cylinder as a gaseous fuel supply system, a fuel gas supply header in which gaseous fuel is supplied from a gas fuel storage device through a pressure regulating valve and a filter, And a fuel supply valve for supplying gaseous fuel from the fuel gas supply header via the branch pipe. The fuel supply valve injects gaseous fuel into the air supply port to generate air supply in which a predetermined amount of fuel gas is evenly mixed, and enters the engine cylinder via an air supply valve that opens every engine cycle. It is configured to supply.

In a gas engine, it is necessary to supply gaseous fuel for each engine cycle, and it is necessary to accurately adjust the gas concentration in order to efficiently burn in the engine cylinder. Furthermore, in the gas engine, the volume of fuel supplied to the engine cylinder is larger than that of liquid fuel such as gasoline.
For this reason, the fuel supply valve has a large capacity in the form of forming a large opening with a short stroke so that fuel gas can be accurately measured and supplied by regulating the valve opening period by electromagnetic force drive, for example. High-speed solenoid valves are used.

  As such a fuel supply valve, the valve body and the valve seat come into contact with a large area plane with a plurality of concentric grooves, and even when the valve is opened, even a slight stroke of about 0.3 mm or less is used. A large amount of gas can be passed because the body groove and the valve seat groove communicate with each other, and a high-speed opening and closing of about 2 to 3 ms is possible between the fully closed and fully opened state by a powerful solenoid and a powerful spring. It is possible to use a solenoid-driven face-type poppet valve or the like.

  A fine filter is installed on the fuel gas supply side of the fuel supply valve, and since there is little backflow from the air supply pipe to the fuel supply valve, foreign matter usually reaches the valve seat of the fuel supply valve. Never do. However, it cannot be said that a situation where foreign matter enters the fuel supply valve and bites into the fuel supply valve does not occur due to an abnormality in the filter or an abnormality in the engine cylinder. The fuel supply valve closes with the large-area faces of the valve body and valve seat coming into contact with each other, so if a foreign object is caught between the faces, a large amount of gas will leak even if a slight gap is created. Become.

If a gas leakage abnormality occurs in the fuel supply valve, not only will the combustion not occur when the gas concentration of the mixture in the engine cylinder falls outside the flammable range, but the unburned mixture will flow down to the exhaust manifold When the exhaust gas from the cylinder is collected and mixed, the fuel gas is diluted by oxygen in the exhaust gas, and the air-fuel ratio in the exhaust manifold may exhibit an air-fuel ratio that belongs to the combustible range.
If the air-fuel mixture in the exhaust manifold is within the flammable range, the energy released by ignition and combustion in the exhaust manifold is a turbocharger, exhaust gas purification catalyst, boiler, silencer, etc. existing downstream of the exhaust manifold. May be damaged.

  For this reason, when a gas leak occurs when the fuel supply valve is closed, it is desired to detect it immediately and take some measures such as stopping the engine. For this purpose, an abnormality detection device that immediately detects the gas leakage of the fuel supply valve during operation of the gas engine is required.

JP 2006-250141 A JP 2002-332878 A

Patent Document 1 discloses a device that detects a failure that occurs when a hydrogen injection valve that supplies hydrogen as a fuel to a gas engine such as a rotary engine remains open when closed, that is, a gas leak occurs, that is, an open failure. The disclosed open failure detection device is provided with a shutoff valve upstream of the hydrogen injection valve, closes the hydrogen injection valve and the shutoff valve when inspecting, and observes the pressure in the fuel supply passage sandwiched between these valves If the pressure decreases, the hydrogen injector is judged to have a leak.
Since the apparatus described in Patent Document 1 needs to be inspected with the hydrogen shutoff valve closed, it can be inspected only when the engine is stopped. Therefore, it cannot be used to detect and take measures immediately after the occurrence of an accident in which a foreign object becomes caught during operation and cannot be completely closed.

  Patent Document 2 discloses a fuel injection device that can detect a gas leak of an injector (needle valve) that injects fuel gas during supply to a supply manifold of a gas engine. The disclosed fuel injection device eliminates the deviation between the actual excess air ratio obtained by detecting the oxygen concentration in the exhaust manifold and the target excess air ratio obtained from the engine speed and the supercharging pressure in the air supply manifold. In this way, the opening degree of the injector of the fuel injection device is adjusted, and if the difference between the valve opening command at that time and the valve opening command of the injector under the same conditions in the initial stage of use becomes large, it is determined that unintended leakage has occurred It is.

  The device described in Patent Document 2 detects leakage in the gas fuel injection device with respect to the supply air, but adjusts the excess air ratio in the supply air manifold before distribution to each of the multiple cylinders. Therefore, it does not correspond to a situation where an abnormality occurs in one cylinder. Further, since the measured value of the excess air ratio in the exhaust manifold is used, an abnormality cannot be detected at least until a change appears in the exhaust manifold, and it does not help to take a quick response.

  The oxygen concentration in the exhaust gas just discharged from the cylinder is about 12% to 13% when the fuel supply valve is normal and burns normally, and about 20% when misfiring. On the other hand, when a failure occurs that the fuel supply valve cannot be completely closed due to, for example, a foreign object being caught, gas fuel accumulates at a high concentration in the supply air at the supply port, and the fuel concentration is out of the combustible range. When the air is supplied to the cylinder, it is exhausted without being combusted in the combustion chamber, so that the oxygen concentration in the exhaust port is greatly reduced.

  Utilizing this phenomenon, an oxygen concentration sensor is installed in the exhaust port for each cylinder, and the oxygen concentration in the exhaust gas is measured. If the oxygen concentration in the exhaust gas is significantly lower than the value during normal combustion, an alarm is issued. It is conceivable to generate

  However, the method of detecting an abnormality of the fuel supply valve based on the oxygen concentration in the exhaust port cannot detect the abnormality until at least the low-oxygen mixture with excessive fuel is exhausted to the exhaust port. Therefore, it is difficult to effectively suppress the phenomenon of causing afterfire by mixing with oxygen flowing from other cylinders in the exhaust manifold.

  Therefore, the problem to be solved by the present invention is an apparatus and method capable of detecting and notifying an abnormality of a fuel supply valve that injects and supplies gaseous fuel during supply in a gas engine, and particularly occurs during operation of the fuel supply valve. An object of the present invention is to provide an abnormality detection device and method for a fuel supply valve in a gas engine that can quickly detect gas fuel leakage when the valve is closed.

  In order to solve the above problems, an abnormality detection device for a fuel supply valve that supplies gaseous fuel to an air supply port in a gas engine of the present invention includes an oxygen concentration sensor installed in the air supply port and an oxygen concentration signal of the oxygen concentration sensor. And an abnormal transmission device that determines that the fuel supply valve is abnormal and outputs an abnormal signal when the oxygen concentration of the air supply port is lower than a threshold value stored in advance.

  Further, in order to solve the above-mentioned problem, the abnormality detection method of the fuel supply valve for supplying gaseous fuel to the supply port in the gas engine of the present invention measures the oxygen concentration in the supply port, and the measured oxygen concentration is preset. The fuel supply valve is judged to be abnormal when it falls below the threshold value, and an abnormal signal is output.

  When the fuel supply valve is normal, gaseous fuel does not flow into the supply port when the fuel supply valve is closed, so that the oxygen concentration is substantially the same as that of the atmosphere. Further, even during the opening period of the fuel supply valve, the air supply valve is open, and the gaseous fuel supplied from the fuel supply valve is transported to the air supply and quickly fed into the combustion chamber. As long as the fuel injection jet is not directly applied, the measured value of the oxygen concentration is almost the same as that of the atmosphere.

  On the other hand, when some abnormality such as a foreign matter is caught in the fuel supply valve and the valve cannot be completely closed, gaseous fuel continues to be supplied from the high-pressure fuel header to the air supply port. When the air supply valve is closed in this state, the supply of air is stopped, so that the oxygen concentration in the air supply port decreases rapidly. In particular, when the rotational speed of the engine is low, the actual time during which the intake valve is closed during one cycle becomes longer, so that the oxygen concentration in the supply port is significantly reduced.

  The abnormality detection device for a fuel supply valve in a gas engine according to the present invention monitors an oxygen concentration in an air supply port with an oxygen concentration sensor, and detects an abnormality in the fuel supply valve when the oxygen concentration falls below an appropriate threshold. It is judged that has occurred and an alarm is given.

In the present invention, when a leakage accident occurs in the fuel supply valve, an abnormality of the fuel supply valve can be detected immediately after the air supply stroke is completed in the same cycle. In addition, the oxygen concentration of the measurement target is stable within a narrow range of approximately 20 to 21% over the entire period when normal, and the oxygen concentration rapidly decreases when abnormal, so the threshold for detecting abnormality is, for example, By setting a relatively high value such as 15%, it is easy to detect even at high speed rotation, and it is possible to detect quickly even at low speed rotation.
According to the present invention, abnormalities in the fuel supply valve such as foreign object biting that occurred during engine operation are detected and notified immediately with high reliability, so appropriate measures are taken to prevent a fuel leakage accident from developing into a major accident. Can take.

  The abnormality detection device may acquire the oxygen concentration information when the rotation of the crankshaft reaches an appropriate phase position based on the cycle phase. The cycle phase can be determined based on a measurement signal input directly from a rotational phase meter that detects rotation of the crankshaft. Moreover, it can also input via an engine control apparatus. Furthermore, at a specific phase position, a command signal generated by the engine control device can be input and used as information acquisition timing.

  The apparatus and method for detecting an abnormality of a fuel supply valve in a gas engine according to the present invention immediately when a leakage abnormality occurs during a valve closing period due to a foreign matter being caught in the fuel supply valve in the gas engine. Since an abnormality is detected and an abnormality signal is generated, it becomes possible to take effective measures before an accident such as combustion in the exhaust manifold develops.

It is a flow sheet explaining the abnormality detection apparatus of the fuel supply valve in the gas engine which concerns on one Example of this invention. It is sectional drawing which shows the attachment position of the oxygen concentration sensor in a present Example. It is a graph showing the oxygen concentration in a supply port at the time of the fuel supply valve foreign material biting in a present Example. It is a graph explaining the abnormality detection principle of a present Example. It is a graph which shows the example of oxygen concentration change at the time of abnormality in the air supply port of a present Example. It is a flowchart explaining the abnormality detection procedure of a present Example.

Hereinafter, embodiments of a fuel supply valve abnormality detection device and method in a gas engine of the present invention will be described with reference to the drawings. In the drawings with different figure numbers, the same reference numerals are assigned to the components having the same functions to facilitate understanding.
FIG. 1 is a flow sheet showing an outline of a gas engine to which a fuel supply valve abnormality detection device according to one embodiment of the present invention is applied.

In the gas engine 10 according to the present embodiment, a space surrounded by the cylinder head 20, the side wall of the engine cylinder 11 and the piston 12 is used as a combustion chamber, as in the case of an internal combustion engine using liquid fuel. The air supply port 13 is connected via the exhaust valve 16, and the exhaust port 14 is connected via the exhaust valve 16.
When the air supply valve 15 is opened to supply air supply mixed with fuel gas to the combustion chamber, and the ignition plug 19 ignites, the gas in the combustion chamber expands and the piston 12 is pushed down in the engine cylinder 11 to connect the connecting rod. The crankshaft 21 is rotated via

The crankshaft 21 is continuously rotated by being driven with an appropriate phase difference by the pistons of the multiple cylinders constituting the gas engine. As the crankshaft 21 rotates, the exhaust valve 16 opens while the piston 12 is pushed up through the bottom dead center, and the combustion gas is removed through the exhaust port 14.
When the crankshaft 21 rotates, the generator 22 can be driven to generate electric power.
The combustion chamber is composed of a main combustion chamber 17 in which the piston 12 reciprocates, and a sub chamber 18 having an opening in the ceiling of the main combustion chamber 17 and provided with a spark plug 19 to improve performance.

  The supply air is supplied to the supply air manifold 23 through the supercharger 35. The air supply manifold 23 is connected to the air supply ports 13 of a plurality of cylinders by branch pipes, and distributes homogeneous air supply to each cylinder. The supercharger 35 uses the energy of the exhaust gas to increase the supply air density, and the output of the engine can be increased by increasing the supply air density.

In each cylinder of the gas engine 10, for each cylinder, gaseous fuel is injected and injected into the air supply at the air supply port 13 to generate an air-fuel mixture having an appropriate gas concentration and supply it to the combustion chamber.
On the other hand, the exhaust gas discharged to the exhaust port 14 gathers in the exhaust manifold 24 connected to the exhaust ports 14 of a plurality of cylinders by branch pipes, and then is connected to a supercharger 35, a deodorizing and denitrating device 36, a boiler 37, and a silencer. The exhaust gas processing device such as 38 is sequentially passed and released to the atmosphere.
The deodorization / denitration device 36 is a device that removes odor components and nitrogen oxides using an adsorbent or a catalyst.

  The gaseous fuel is supplied to and held in a gaseous fuel storage device 31 such as a cylinder or tank, is supplied to the regulator 33 via the shutoff valve 32, and is adjusted to an appropriate pressure by the regulator 33 before being supplied to the fuel header 25. Supplied. The fuel header 25 includes a branch pipe 28 for each cylinder, and a fuel supply pipe 29 is connected to the tip of the branch pipe 28 via a throttle 34. The lower end of the fuel supply pipe 29 is connected to the supply port of the fuel supply valve 26, and the gaseous fuel from the header 25 is supplied to the fuel supply valve 26.

  The fuel supply valve 26 is an electromagnetic valve that forms a large opening with a small stroke and allows a large amount of gas to flow in a short time. For example, a solenoid-driven face-type poppet valve having a valve body formed of a flat plate is used. The flat plate of the valve seat and the flat plate of the valve body are each formed with a concentric through-groove. When the valve seat and the valve body are in plane contact with each other, the through-grooves are offset from each other to block the passage. When the valve seat and the valve body are separated from each other, the plurality of through grooves are electrically connected to each other to form a large opening when the valve seat is separated from the valve body.

Further, by adjusting the gaseous fuel in the fuel header 25 to a sufficiently high pressure so that the differential pressure between the fuel pressure and the supply air pressure is about 50 to 200 kPa, a large flow rate can be secured.
Furthermore, the electromagnet that attracts the valve body of the fuel supply valve 26 is strong, and the valve body can be removed from the valve seat in a short time to form a large opening, and the spring that presses the valve body against the valve seat is also powerful. Therefore, the opening and closing of the valve has a quick response of about 2 to 3 ms.

The outlet of the fuel supply valve 26 opens to the air supply port 13, and gaseous fuel is injected and mixed into the air supplied from the air supply port 13.
The supply amount of the gaseous fuel can be set with high reproducibility according to the valve opening time of the fuel supply valve 26.

  Each cylinder is controlled by the engine control device 40. The engine control device 40 includes, for example, an air supply pressure signal supplied from a pressure transmitter 42 provided at the air supply port 13 and a crank angle signal supplied from a rotational phase meter 41 that measures the rotational phase of the crankshaft 21. Further, an index of specifications for measuring the performance of the generator 22 is input to grasp the state of the gas engine 10.

Based on this information, the current output of the generator 22 is calculated and compared with the set target output. If there is a deviation, various control variables are adjusted to eliminate the deviation. The engine control device 40 can control the air-fuel ratio in the combustion chamber by adjusting the amount of gaseous fuel supplied during supply using the supply pressure. Further, it has functions of calculating opening / closing timings of the ignition plug 19, the air supply valve 15, the exhaust valve 16, the fuel supply valve 26, etc., and issuing an operation command to them based on the crank angle.
Note that the engine control device 40 can perform an emergency stop of the engine by giving a valve closing command to the fuel supply valves 26 in all the cylinders when necessary.

The abnormality detection device for the fuel supply valve according to this embodiment has a function of detecting an abnormality of the fuel supply valve 26 during operation.
The fuel supply valve 26 has a valve seat formed of a flat plate and a valve body formed of a flat plate that contacts the flat surface of the flat plate of the valve seat and blocks the flow path, and opens and closes with a very small stroke of less than 0.3 mm. Switch.
For this reason, even if a very small foreign object is inserted, the flat surface of the valve body and the flat surface of the valve seat cannot be closed tightly, and the valve cannot be closed properly. Mixed in.

When a gas leakage abnormality occurs in the fuel supply valve 26, the gas concentration of the air-fuel mixture in the combustion chamber shifts to a richer side than the combustible range and combustion does not occur, or the unburned air-fuel mixture flows down to the exhaust manifold 24 and other cylinders. The air-fuel ratio of the air-fuel mixture in the exhaust manifold 24 may enter the flammable range when it is combined with the exhaust gas from the exhaust gas and mixed with the oxygen in the exhaust gas.
Further, even after the air supply valve 15 is closed, gaseous fuel is supplied, and an air-fuel rich mixture is generated in the air supply port 13, so that it does not burn even if supplied to the combustion chamber in the next air supply stroke. In the exhaust manifold 24 that is discharged to the exhaust port 14 and collects exhaust gases from other cylinders, there is a risk that an air-fuel mixture in the combustible range is continuously generated.

If surplus energy is released when the air-fuel mixture in the exhaust manifold 24 is in the combustible range and ignites and burns in the exhaust manifold 24, the structure of the supercharger 35 existing downstream, the adsorbent of the deodorizing and denitration device 36, There is a risk of damaging the catalyst, the heat exchanger of the boiler 37, the structure of the silencer 38, and the like.
If these devices are damaged, a large-scale repair work is required, resulting in a great damage.

For this reason, in this embodiment, when a gas leakage occurs when the fuel supply valve 26 is closed, an abnormality detection device that immediately detects and informs the gas leakage is transmitted, and an alarm signal is transmitted to the engine control device 40. It is possible to take a predetermined emergency stop measure or to take appropriate measures such as an emergency stop of the engine based on advanced judgment by informing the operator.
When the oxygen concentration sensor 51 provided in the air supply port 13 and the oxygen concentration signal of the oxygen concentration sensor 51 are input to the abnormality detection device of this embodiment, the oxygen concentration of the air supply port 13 is lower than a prestored threshold value. And an abnormality transmitter 50 that determines that the fuel supply valve 26 is abnormal and outputs an abnormality signal.

FIG. 2 is a partially cutaway front view for explaining the position where the oxygen concentration sensor 51 for measuring the oxygen concentration in the air supply port 13 is installed.
A fuel supply pipe 29 for measuring and supplying gaseous fuel from the fuel header 25 is connected to the inlet of the fuel supply valve 26. The outlet of the fuel supply valve 26 is opened to the air supply port 13, and gaseous fuel is injected and mixed during supply of the air supply port 13 when the fuel supply valve 26 is open.

  Here, the oxygen concentration sensor 51 is attached to the side wall of the supply port 13 immediately downstream of the fuel supply pipe 29, measures the oxygen concentration of the supply air, and transmits an oxygen concentration signal to the abnormality transmitter 50. The oxygen concentration sensor 51 is installed not at a position that directly receives fuel injection from the fuel supply valve 26 but at a position before the injected gaseous fuel and air are mixed in a normal state. Therefore, when the fuel supply valve 26 is operating normally, the measurement output of the oxygen concentration sensor 51 becomes a value corresponding to the oxygen concentration of the air taken in as supply air.

  However, if a failure occurs in the fuel supply valve 26 such that foreign fuel is caught in the gas supply port 13 even during the valve closing period, the supply stroke ends and the supply valve 15 is closed. If new air does not flow into the supply port 13, the ratio of gaseous fuel in the supply air staying in the supply port 13 increases rapidly, and the oxygen concentration decreases.

FIG. 3 is a graph showing the oxygen concentration in the air supply port 13 when the fuel supply valve bites foreign matter and cannot be sealed. The graph shows the engine speed and load on the horizontal axis and the oxygen concentration on the vertical axis, and the oxygen concentration when the fuel supply valve 26 is normal and abnormal is represented by a bar graph with the engine speed and load as parameters. It is a thing.
The oxygen concentration when the fuel supply valve 26 is abnormal is calculated and displayed as a value in which fuel is accumulated only for one cycle.

  While the engine speed is low, the cycle period is long and the leakage time of the gaseous fuel is long, so that the residual amount of oxygen is further reduced and the oxygen concentration in the supply port 13 becomes almost zero. When the engine speed increases, the amount of oxygen leakage per cycle decreases and the amount of decrease in oxygen concentration decreases. However, even when the engine speed is 722 rpm or 720 rpm, the oxygen concentration after one cycle period is up to about 15%. It turns out that it falls.

FIG. 4 is a graph showing time on the horizontal axis and oxygen concentration on the vertical axis, and is a graph for conceptually showing the oxygen concentration change in the air supply port 13 and explaining the abnormality detection principle of this embodiment.
While the fuel supply valve 26 is normal, the oxygen concentration in the air supply port 13 is 20 to 21%, which is almost the same as the atmosphere. Even if the fuel supply valve 26 is operated and gaseous fuel is injected, the oxygen concentration detected by the oxygen concentration sensor 51 does not change much.

  Even if the fuel supply valve 26 becomes abnormal and the gaseous fuel is supplied to the supply port 13 even when the fuel supply valve 26 is closed, the oxygen concentration in the supply port 13 rapidly decreases as soon as the supply stroke is completed. When the next air supply stroke is reached, the fuel-rich air supply is pushed into the combustion chamber by being pushed by fresh air drawn from the outside air. At this time, normally, as shown in FIG. 4, due to the relationship between the volume of the air supply port 13 and the volume of the combustion chamber, the mixture and air of the air supply port 13 are interchanged so that the oxygen concentration does not recover. . Even when all the air-fuel mixture in the air supply port 13 is replaced with new air supply during the air supply stroke, if the failure that the fuel supply valve 26 leaks in the closed state has not been resolved, the air supply stroke is completed. Again, the oxygen concentration decreases rapidly.

  Thus, the oxygen concentration at the air supply port shows a value similar to that of air when the fuel supply valve 26 is normal, and suddenly when the air supply stroke is completed when the fuel supply valve 26 has a failure. Therefore, it can be determined that there is an abnormality when the oxygen concentration falls below the threshold. An appropriate value for the threshold value of the oxygen concentration may be selected depending on the engine speed. However, for example, if the threshold value is 17%, the oxygen concentration threshold value can be used even when the engine speed reaches 720 rpm.

  Depending on the characteristics of the oxygen concentration sensor 51 and the installation status at the air supply port 13, the detected oxygen concentration may decrease due to fuel injection. In such a case, there is a possibility that the normal fuel supply valve 26 may be mistaken as abnormal if it is determined based only on the oxygen concentration decrease amount. Therefore, it is correct only when the timing for monitoring the oxygen concentration is set to an appropriate cycle phase time point to avoid the noise of the oxygen concentration lowering phenomenon caused by injection and to be considered that the oxygen concentration lowering is caused by the abnormality of the fuel supply valve 26 Judgment can be made.

  The phenomenon that the oxygen concentration of the supply port 13 decreases due to the abnormality of the fuel supply valve 26 is, for example, the timing immediately after the supply valve 15 is closed or the bottom dead center position of the piston 12 at which the compression stroke after supply starts. It can be reliably detected by using the oxygen concentration at a nearby timing. For this reason, the abnormality transmission device 50 can further capture the cycle phase information, avoid the fuel injection timing, and evaluate the decrease in oxygen concentration after the supply valve 15 is closed.

The cycle phase information may be directly received from the rotational phase meter 41 installed on the crankshaft 21 and used for designating the time for evaluating the oxygen concentration.
In addition, the engine control device 40 supplies a valve closing command signal for the fuel supply valve 26 and generates a command signal for the valve using the bottom dead center passage information of the piston 12. The control device 40 may input and use a closing command signal for the fuel supply valve 26 or bottom dead center passage information of the piston 12.

Although this determination procedure is simple, if an abnormality occurs in the fuel supply valve 26, it can be detected immediately after the air supply stroke is completed. Therefore, appropriate measures can be taken before the exhaust gas aftertreatment process is seriously affected. There is room to take.
If the abnormality transmission device 50 supplies a signal for notifying the occurrence of abnormality when the abnormality is detected to the engine control device 40 so that the engine control device 40 immediately takes an emergency stop, the air-fuel mixture in the exhaust manifold 24 can be obtained. No combustion occurs, and it is possible to prevent damage to each device in the exhaust gas treatment process.
Also, the abnormality transmission device 50 and the engine control device 40 are not directly connected, but the abnormality transmission device 50 notifies the occurrence of the abnormality, and the operator receives the notification and takes appropriate measures via the engine control device 40. May be.

FIG. 5 is a graph showing an example of oxygen concentration change at the time of abnormality in the air supply port of the present embodiment. In the figure, the abscissa indicates the crank angle with zero when the piston is at top dead center, and the ordinate indicates the oxygen concentration. When the piston is at top dead center at startup, the fuel supply valve 26 The result of having measured the state that the oxygen concentration in the air supply port 13 decreases when the fuel leaks because it cannot be closed is shown by the oxygen concentration sensor 51.
In the example shown in the figure, the oxygen concentration, which was about 19% at the beginning, suddenly decreases and becomes almost zero when the crank angle reaches 240 °, and fuel leakage based on the decrease in oxygen concentration is sufficiently detected within one rotation. It is understood that is possible.

FIG. 6 is a flowchart illustrating an abnormality detection procedure executed by the fuel supply valve abnormality detection device.
The abnormality detection device of the present embodiment takes in the information of the cycle phase from the engine control device 40 (S11), and the intake valve 15 is closed, for example, the timing of bottom dead center in the supply and compression strokes of the target cylinder. If this is the time (S12), the measurement signal at the timing when the supply valve 15 is closed of the oxygen concentration sensor 51 that measures and outputs the oxygen concentration in the supply port 13 is captured (S13). The measured value is compared with a predetermined threshold (S14), and when the oxygen concentration becomes lower than the threshold, it is determined that an abnormality has occurred in the fuel supply valve 26, and an abnormality detection signal is generated (S15). When the current time is not the closing period of the air supply valve (S12) or when the oxygen concentration is higher than the threshold value (S14), the process returns to the initial stage of the work and returns to the first stage (S11) again. The first operation in the next work procedure starts.
The abnormality detection signal may be supplied to the engine control device 40 to start an emergency stop operation. Alternatively, an alarm may be used to determine the operator's judgment.

The procedure shown in FIG. 6 is such that the abnormality transmission device 50 selects the timing for evaluating the oxygen concentration measurement value based on the phase signal acquired from the engine control device 40.
If the oxygen concentration sensor does not respond to a decrease in concentration during normal fuel injection, the procedure (S11, S12) based on the phase signal is not necessary.
Further, the cycle phase signal may be directly received by the abnormality detection device from the rotation phase meter 41 installed on the crankshaft 21.

In order to determine the closed state of the fuel supply valve 26, there is a method using an operation command signal of the fuel supply valve 26 or a cycle phase signal when the air supply valve 15 is closed. For example, after a command to close the fuel supply valve 26 is issued, if an appropriate time elapses, the flow of gaseous fuel normally stops completely, and the oxygen concentration of the supply port 13 returns to almost the oxygen concentration of air. ing. Therefore, by acquiring the valve closing command signal for the fuel supply valve 26 from the engine control device 40, a timing signal used for the determination can be easily obtained. Alternatively, since the air supply valve 15 is closed after an appropriate time has elapsed after the fuel supply valve 26 is closed, a cycle phase signal may be used when the air supply valve 15 is closed or while it is closed.
Further, the abnormality transmission device in the present embodiment may be configured by a dedicated electronic circuit or may be configured by a general-purpose microcomputer. Furthermore, you may make it comprise with a part of electronic circuit which comprises the control apparatus for gas engines.

  In the present embodiment, the invention will be described by taking a four-cycle gas engine having a sub chamber as an example, but the technical idea according to the invention can be applied even if there is no sub chamber or a two-cycle engine. Needless to say, it can be done. Moreover, although the gas engine demonstrated in a figure drives a generator, it may drive a wheel, a screw, etc., and may utilize it for operation of a vehicle or a ship.

  The fuel supply valve abnormality detection device and method in the gas engine according to the present invention detects an abnormality of the fuel supply valve immediately after the occurrence, so that the detection signal is supplied to the control device as it is to make an emergency stop or notify the operator. It is possible to prevent damage to equipment and catalysts in the combustion gas treatment process by promoting appropriate countermeasures, so it can be used effectively in the field of power generation and rotational power using gas engines. can do.

DESCRIPTION OF SYMBOLS 10 Gas engine 11 Engine cylinder 12 Piston 13 Supply port 14 Exhaust port 15 Supply valve 16 Exhaust valve 17 Main combustion chamber 18 Subchamber 19 Spark plug 20 Cylinder head 21 Crankshaft 22 Generator 23 Supply manifold 24 Exhaust manifold 25 Fuel Header 26 Fuel supply valve 28 Fuel supply pipe (branch pipe)
DESCRIPTION OF SYMBOLS 29 Fuel supply pipe 31 Gaseous fuel storage device 32 Shut-off valve 33 Regulator 34 Restriction 35 Supercharger 36 Deodorization denitration device 37 Boiler 38 Silencer 40 Engine control device 41 Rotary phase meter 42 Pressure sensor 50 Abnormal transmission device 51 Oxygen concentration sensor

Claims (5)

An abnormality detection device that detects an abnormality of a fuel supply valve that supplies gaseous fuel to an intake port in a gas engine,
An oxygen concentration sensor installed at the air supply port;
An abnormality transmitter that inputs an oxygen concentration signal of the oxygen concentration sensor and determines that the fuel supply valve is abnormal and outputs an abnormality signal when the oxygen concentration of the supply port is lower than a prestored threshold;
An abnormality detection device for a fuel supply valve in a gas engine, comprising: 2. The abnormality transmitting device acquires the cycle phase signal of the gas engine, and acquires the oxygen concentration signal when the rotational phase of the crankshaft reaches an appropriate phase position. For detecting an abnormality of a fuel supply valve in a gas engine in Japan.   3. The gas according to claim 1, wherein the cycle phase signal of the gas engine is acquired directly from a sensor that detects a rotational phase of a crank that rotates in the gas engine or indirectly through an engine control device. An abnormality detection device for a fuel supply valve in an engine. An abnormality detection method for detecting an abnormality in a fuel supply valve that supplies gaseous fuel to an intake port in a gas engine,
Measuring the oxygen concentration at the air supply port;
When the oxygen concentration falls below a preset threshold, it is determined that the fuel supply valve is abnormal, and an abnormality detection signal is output.
An abnormality detection method for a fuel supply valve in a gas engine.   A gas engine comprising the fuel supply valve abnormality detection device according to any one of claims 1 to 3.

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