KR20140132827A - Knocking control system and method for dual fuel engine - Google Patents

Abstract

The present invention relates to a system and a method for controlling knocking in a dual fuel engine in a gas fuel operation mode. According to the present invention, a system for controlling knocking in a dual fuel engine comprises: an oil fuel injector (22) to inject oil fuel into a combustion chamber; a pilot injector (24) to inject pilot fuel; a gas inlet valve (26) to inject gas fuel to an intake port; a knock sensor (12) installed in each of cylinders, and sensing a knock; a combustion pressure sensor (14) installed in each of the cylinders, and sensing combustion pressure; an injection control panel (120) connected to the pilot injector (24) and the gas inlet valve (26), and controlling the operations of the pilot injector (24) and the gas inlet valve (26); a cylinder monitoring panel (130) connected to the knock sensors (12) and the combustion pressure sensors (14), and generating knock information or cylinder pressure information by monitoring a knock state and combustion pressure in each of the cylinders; and a main control panel (100) determining whether the knock is generated in each of the cylinders or not based on the knock information or the cylinder pressure information applied from the cylinder monitoring panel (130), generating an increase or a decrease control signal for the duration of injection (DOI) of the gas fuel while advancing or retarding a pilot injection timing, increasing or decreasing the DOI of the gas fuel, or advancing or retarding the pilot injection timing by a knock removal program input beforehand, and issuing the generated control signal to the injection control panel (120) and/or the gas inlet valve (26).

Description

TECHNICAL FIELD [0001] The present invention relates to a knocking control system and a knock control system for a dual fuel engine,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a dual fuel-rich engine using an oil fuel and a gaseous fuel, and more particularly, to a dual fuel engine knock control device for effectively monitoring a knocking state and a combustion state of a cylinder, ≪ / RTI >

In a gas carrier such as liquefied natural gas (LNG), gas fuel stored in a storage tank is easily used as fuel, and gas used in the tank is not re-liquefied. And a dual fuel engine that selectively or simultaneously uses gaseous fuel. In the case of large-scale diesel engines used in power generation facilities of offshore structures, marine structures, or plants using gas such as LNG or LPG, dual fuel engines are also introduced that can use gaseous fuels together.

Large diesel engines using dual fuel (diesel engines) are used in a gas fuel operating mode using gaseous fuels, an oil fuel operating mode using oil fuels (eg, Marine Diesel Oil, Heavy Fuel Oil, etc.) And a mixed operation mode in which fuel is simultaneously used.

The oil fuel is injected into the combustion chamber by an oil fuel injector provided in each cylinder head, the gaseous fuel is distributed from the main feed pipe to each cylinder-specific distribution pipe, and the gas amount in the gas admission valve (GAV) assembly Is regulated and injected into the intake port of the cylinder head through the gas injector.

Since the dual fuel engine is based on a diesel engine that self-ignites by compressing the intake air to high temperature and high pressure unlike a gasoline engine that ignites the fuel by spark plug, it induces ignition of the gas fuel And a pilot injector (Micro Pilot Injector) as a small-sized oil fuel injector.

Since gas fuels such as natural gas have a low self-ignition temperature and a high self-ignition temperature of around 550 ° C, just before injecting the main fuel, gaseous fuel in the gas fuel operating mode, A pilot injection process (pilot injection process) by injecting pilot oil (eg, Marine Diesel Oil, Marine Gas Oil, etc.) by injecting a small amount of fuel through the injector can stably ignite the gaseous fuel.

Further, even in the oil fuel operation mode, it is possible to improve the NOx improvement and the combustion performance by improving the combustion environment of the combustion chamber by injecting a small amount of pilot oil through the pilot injector immediately before injecting the diesel fuel as the main fuel.

As described above, in the dual fuel engine, it is necessary to provide a separate supply system for the supply of the two main fuel and the pilot oil, and to operate in two operation modes or more, The control system is also very complicated.

In particular, since the dual fuel engine is based on a diesel engine, precise operation control in the gas fuel mode is a very important factor in determining whether or not it can operate in the gas fuel mode. For example, in the oil fuel operation mode, combustion is caused by compression ignition of the fuel as in a general diesel engine, but in the gas fuel operation mode, pilot injection must be performed in advance to induce ignition of the gaseous fuel. Therefore, even if the ignition timing by the gaseous fuel is set to be the same in the gas fuel operation mode, the progress of the combustion (explosion), the combustion pressure, and the timing of occurrence of the maximum pressure are different for each cylinder.

Therefore, in the above-described dual fuel engine, it is very important to monitor the knocking situation occurring in real time in each cylinder and remove the factor of knocking early in order to stably maintain the operating characteristic of the engine. Balancing between cylinders is also very important.

In order to stabilize the operation through the knocking control and cylinder balancing control, it is necessary to monitor the combustion state of each cylinder in real time, to quickly detect whether there is a possibility of combustion that may cause knocking, The possibility of balancing between the cylinders should be maintained in advance.

Published Patent Publication No. 10-2010-0074084 (published on July 1, 2010) Published Patent Publication No. 10-2008-0078504 (Published Aug. 27, 2008) Open Patent Publication No. 10-2004-0095274 (published on November 12, 2004)

Therefore, the present invention effectively monitors the combustion state of each cylinder, and recognizes the possibility of knocking early, thereby effectively coping with the combustion, thereby maintaining the combustion state of the cylinder normally. Thus, An object of the present invention is to provide a knock control device and method for a fuel engine.

In order to achieve the above object, a knocking control apparatus for a dual fuel engine according to the present invention includes: an oil fuel injector for injecting an oil fuel into a combustion chamber; A pilot injector for injecting pilot fuel; A gas inflow valve for injecting gaseous fuel into the intake port; A knock sensor installed in each cylinder for sensing a knock; A combustion pressure sensor installed in each cylinder for sensing a combustion pressure; An injection control panel connected to the pilot injector and the gas inlet valve to control the operation; A cylinder monitoring panel, connected to the knock sensor and the combustion pressure sensor, for monitoring the knock condition and the combustion pressure of each cylinder to generate knock information or cylinder pressure information; The knocking degree of each cylinder is determined based on the knock information or the cylinder pressure information applied from the cylinder monitoring panel, and the advance or retard of the pilot injection timing or the gas fuel injection duration time DOI), or an advance or a decrease control signal of the gaseous fuel injection duration (DOI) in parallel with the advance or perception of the pilot injection timing, and transmits the generated control signal to the injection control panel and / And includes a main control panel for delivering to the valve.

In one embodiment, the cylinder monitoring panel includes a knock monitoring unit that receives a noise signal from a knock sensor of each cylinder, monitors the knock signal, and transmits a knock signal acquisition result to the main control panel when a knock related signal is captured. And a combustion monitoring unit that receives a signal of a combustion pressure applied from a combustion pressure sensor of each cylinder, captures a knock related pressure signal, and transmits it to the main control panel.

The knocking control method for a dual fuel engine according to the present invention includes the steps of inputting a knock signal when monitoring a sensing signal input from a knock sensor and a combustion pressure sensor installed in a cylinder (step S501); Stopping the gaseous fuel operation mode when the knock level is equal to or greater than a preset knock limit value (step S503); (Step S504), when the knock level is lower than a preset knock limit value, the knock canceling process is performed by controlling the combustion related factor by a preset knock cancel option; And a process of continuing the knock canceling process until the knock signal disappears from a signal input from the knocking sensor and the combustion pressure sensor by the knock removing process (step S505).

In one embodiment, the knock removal processing method may be a method of adjusting the ignition timing by controlling the pilot injection timing, or adjusting the gas fuel amount by controlling the gas fuel injection duration (DOI) And the injection duration time (DOI) are adjusted in parallel.

The pilot injection timing adjustment for knock removal is characterized by delaying the pilot injection timing.

The adjustment of the gaseous fuel injection duration (DOI) for knock removal is characterized by reducing the gaseous fuel injection duration (DOI).

According to the apparatus and method for controlling knocking of a dual fuel engine according to the present invention, a knock sensor and a combustion pressure sensor are installed in a cylinder, information on the knock sensor and combustion pressure sensor is monitored in real time through a cylinder monitoring panel, The knocking can be cut off early by adjusting the pilot injector or the gas fuel injection duration of the cylinder, so that the balancing between the cylinders can be maintained and stable operation can be achieved.

It can also improve stability and reliability in a gaseous fuel operation mode of a dual fuel engine based on a diesel engine.

1 is a general diagram showing the configuration of an engine control system and a knocking monitoring element of a dual fuel engine according to the present invention.
2 is a diagram showing a knock control and combustion monitoring system of an engine control system of a dual fuel engine according to the present invention.
3 is a view for explaining two factors for determining the cylinder knocking state in the knocking control process according to the present invention.
4 is a block diagram for explaining an example of an object to be controlled by the controller in the knocking control according to the present invention.
5 is a flowchart illustrating a knocking control process according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a knocking control apparatus and method of a dual fuel engine according to the present invention will be described in detail with reference to the accompanying drawings.

An embodiment of an arrangement structure of an engine control system and a knocking monitoring system of a dual fuel engine will be described in detail.

In the present specification and claims, "or / and" are defined to include each and every one or more combinations of the mentioned items.

1 is a general diagram showing the configuration of an engine control system and a knocking monitoring element of a dual fuel engine according to the present invention.

1 shows a large dual fuel engine for a marine or a plant and its control system in which the dual fuel engine 10 is operated in an oil fuel operation mode using oil fuel and a gas fuel operation mode using gas fuel .

The overall control of the dual fuel engine 10 is performed in a main control panel 100 having a central control unit of an engine control system and is controlled by a local operating panel (LOP) Speed and output, air fuel ratio, main fuel supply cutoff, pilot fuel cutoff, fuel mode switching, fuel (fuel injection) control, and fuel injection control are performed by receiving all the data of the engine from the engine control unit 110 and the injection control panel Distribution control, cooling medium temperature, engine operation state calculation, control for engine safety, etc., and performs the cylinder balancing control and the knock control operation according to the present invention.

In order to provide two kinds of fuel, the cylinder head 20 of the dual fuel engine 10 is provided with an oil fuel injector 22 for injecting the oil fuel into the combustion chamber and a pilot injector 24, and a gas inlet valve (GAV) 26 for injecting gaseous fuel into the intake port is provided.

The local operating panel 110 is installed for each individual engine and communicates the respective engine status information and commands with the main control panel 100 while all status values of each engine are displayed and monitored. The local operating panel 110 may also have a touch screen for displaying the measurements of the individual engines and displaying the input or action menu buttons so that the manager can perform monitoring while operating the respective engine have.

The injection control panel 120 is connected to the pilot injector 24 and the high pressure pump for pilot injection and is connected to the gas inlet valve 26. These are connected to the injection control panel 120 under the control of the main control panel 100 .

In the present invention, the main control panel 100 controls opening and closing of the oil fuel feed path and the gas fuel feed path and driving of the pump in accordance with the oil fuel or gas fuel operation mode, and controls the overall and individual adjustment signals The injection control panel 120 causes the injection control panel 120 to control the injection timing of the pilot injector 24 and / or the gas fuel injection duration (DOI, Duration Of Injection) of the gas inlet valve 26, .

In the present invention, each cylinder (i.e., combustion chamber) of the dual fuel engine 10 for the knock control and the cylinder balancing control is provided with a knock sensor 12 for sensing the knock and a combustion pressure sensor 14 for sensing the combustion pressure, Respectively.

In this embodiment, a separate cylinder monitoring panel 130 is provided to more effectively perform knock control and cylinder balancing control. The cylinder monitoring panel 130 is installed separately from the main control panel 100.

The cylinder monitoring panel 130 is connected to the knock sensor 12 and the combustion pressure sensor 14 and monitors knocking information and combustion information input from each cylinder of the engine under the control of the main control panel 100 , And calculates information on the knock pressure and the combustion pressure, and transmits the information to the main control panel 100.

The main control panel 100 performs knock control and cylinder balancing control based on data transmitted from the cylinder monitoring panel 130.

2 is a diagram showing a knock control and combustion monitoring system of an engine control system of a dual fuel engine according to the present invention.

Referring to FIG. 2, the cylinder monitoring panel 130 includes a knock monitoring unit 132 for monitoring the knock state (intensity) of each cylinder, and a combustion monitoring unit 134 for monitoring the cylinder-by-cylinder combustion pressure.

The knocking monitoring unit 132 receives a signal for each cylinder knock condition from the knock sensor 12, captures a signal of a level likely to knock in the noise generated in the cylinder, and outputs the acquired result to the main control panel 100 ).

The combustion monitoring unit 134 receives a signal for each cylinder combustion pressure from the combustion pressure sensor 14 to generate a pressure curve and calculates a combustion maximum pressure Pmax of each cylinder or an average of all the cylinders - the combustion maximum pressure (Pmax_average), and transfers the calculated information to the main control panel 100, and displays the information on the monitoring PC 150.

On the main control panel 100, control options for knock control and cylinder balancing control are programmed in advance. Based on knock information and combustion pressure information from the cylinder monitoring panel 130, knock control and cylinder balancing Control is performed to remove the knocking inducing factor and to control the combustion characteristics among the cylinders to be uniform.

3 is a view for explaining two factors for determining the cylinder knocking state in the knocking control process according to the present invention. See FIG. 2 in parallel.

3, the knocking monitoring unit 132 of the cylinder monitoring panel 130 receives and monitors a noise signal applied from the knock sensor 12 of each cylinder, as shown in the right side of FIG. 3, When a signal related to a related signal (for example, a knock generation signal or a signal of a level judged to have a knocking possibility) is captured (corresponding to a bold solid arrow), the knock signal acquisition result is transmitted to the main control panel 100 .

3, the combustion monitoring unit 134 of the cylinder monitoring panel 130 receives a signal indicative of the combustion pressure applied from the combustion pressure sensor 14 of each cylinder, (For example, a pressure fluctuation signal due to knocking or a pressure fluctuation signal at a level judged to have a possibility of knocking) is captured, the result of capturing the pressure signal is transmitted to the main control panel 100 do.

The main control panel 100 performs a control operation for knock canceling by a knock control option (program) when any one of the above-mentioned two knock signals is reached.

4 is a block diagram for explaining an example of an object to be controlled by the controller in the knocking control according to the present invention.

Referring to FIG. 4, the main control panel 100 controls the gas fuel injection amount (Gas Quantity) by adjusting the duration of the gas fuel injection duration (DOI) corresponding to the load (Rpm / Power) Controlling the opening degree to control the exhaust gas, and controlling the ignition timing by adjusting the pilot injection timing in all operating ranges and when a knock event occurs.

As a result of the cylinder monitoring, when the knock is recognized, the main control panel 100 can perform control to change the pilot injection timing until, for example, the knock is eliminated.

When knocking occurs, the gas fuel injection duration (DOI) can be controlled in addition to or separately from the above ignition timing control.

Further, it is possible to perform control to simultaneously change the pilot injection timing and the gas fuel injection duration (DOI).

Details of the control of the pilot injection timing and the gas fuel injection duration (DOI) in accordance with the knocking detection will be described in detail in the following control process.

5 is a flowchart illustrating a knocking control process according to the present invention. 1 to 3 will be referred to concurrently.

Referring to FIG. 5, during the monitoring of a sensing signal input from the knock sensor 12 and the combustion pressure sensor 14 installed in the cylinder, a knocking signal (e.g., knocking occurs) And the knocking inducing signal that is likely to be developed into knocking is captured), the corresponding knocking signal acquisition result is input from the cylinder monitoring panel 130 to the main control panel 100 (step S501).

Then, the knock pressure is calculated, and the gas fuel operation mode is stopped when the knock level is equal to or higher than a preset knock limit value (step S503). Furthermore, it is preferable to stop the gas fuel operation mode and immediately switch to the oil fuel operation mode. If the knock level is too high to exceed the limit value, it is judged that the abnormal condition has occurred in the cylinder instead of the simple knock.

If the knock level does not reach the predetermined knock limit value, it is determined that the knock control is possible, and the knock canceling process is performed by controlling the combustion related factor according to the preset option (step S504).

The combustion related factors for the knock removing process utilize a method of adjusting the ignition timing by controlling the aforementioned pilot injection timing or a method of adjusting the gas fuel amount by controlling the gas fuel injection duration (DOI).

For example, when the knock is recognized as a result of the cylinder monitoring, the main control panel 100 advances or delays the pilot injection timing (the pilot fuel injection timing in the pilot injector) until the knock is eliminated, ).

The pilot injection timing adjustment range is set to a predetermined range, for example, between -3 crs and + 3 crs as a crank angle, and the adjustment is made within the range.

The pilot injection timing is closely related to the ignition timing of the combustion related factors. Normally, if the pilot injection timing is advanced, the ignition timing is advanced. If the timing is delayed, the ignition timing is delayed. When the pilot injection timing is adjusted within a limited range as described above, the maximum combustion pressure Pmax is increased when the pilot injection timing is advanced and the ignition timing is advanced. On the contrary, when the pilot injection timing is delayed, When the timing is delayed, the maximum combustion pressure (Pmax) tends to decrease.

That is, when the pilot injection timing is delayed (slowed down), the combustion temperature is lowered and the maximum combustion pressure Pmax is lowered so that the knocking of the cylinder can be eliminated. .

Also, for knock control, the gas fuel injection duration (DOI) may be controlled.

Reducing the gaseous fuel injection duration (DOI) reduces the amount of gaseous fuel and makes the mixer lean, thus eliminating knocking. When the knocking disappears, the gas fuel injection duration is restored to the normal level.

Furthermore, the pilot injection timing and the gas fuel injection duration (DOI) can be controlled in parallel.

This control operation continues until the knock signal disappears from the signal input from the knocking sensor 12 or the combustion pressure sensor 14 (step S505).

Then, when the knock control end signal is inputted according to the necessity of the engine control system or the like, the knock removing operation is ended (step S506).

As described above, according to the present invention, a knock sensor and a combustion pressure sensor are installed in a cylinder, information about them is monitored through a cylinder monitoring panel, and knocking can be effectively controlled. It can also improve stability and reliability in a gaseous fuel operation mode of a dual fuel engine based on a diesel engine.

The foregoing is a description of certain preferred embodiments of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein, but may be modified and altered without departing from the spirit and scope of the invention as defined in the appended claims.

10: Engine
12: Knock sensor
14: Combustion pressure sensor
20: Cylinder head
22: Oil fuel injector
24: Pilot injector
26: Gas inlet valve (GAV)
100: Main control panel
110: Local operating panel
120: Injection control panel
130: Cylinder monitoring panel
132: Knock monitoring unit
134: Combustion monitoring unit

Claims (6)

A knock control device for a dual fuel engine using oil fuel and gaseous fuel,
An oil fuel injector 22 for injecting the oil fuel into the combustion chamber;
A pilot injector (24) for injecting pilot fuel;
A gas inlet valve (26) for injecting gaseous fuel into the intake port;
A knock sensor 12 installed in each cylinder for sensing a knock;
A combustion pressure sensor 14 installed in each cylinder for sensing the combustion pressure;
An injection control panel 120 connected to the pilot injector 24 and the gas inlet valve 26 to control the operation thereof;
A cylinder monitoring panel (130) connected to the knock sensor (12) and the combustion pressure sensor (14) for monitoring the knock condition and the combustion pressure of each cylinder to generate knock information or cylinder pressure information;
It is determined whether a knock has occurred in each cylinder based on the knock information or the cylinder pressure information supplied from the cylinder monitoring panel 130. If the knock is detected by the knock canceling program inputted beforehand or the advance or retard of the pilot injection timing, (DOI) increase or decrease, or in parallel with the advance or retard of the pilot injection timing, and the generated control signal to the injection control panel 120 And / or a main control panel (100) for reaching the gas inlet valve (26). The method according to claim 1,
The cylinder monitoring panel (130)
A knock monitoring unit 132 for receiving and monitoring a noise signal applied from the knock sensor 12 of each cylinder and transmitting a knock signal acquisition result to the main control panel 100 when the knock related signal is captured; And
And a combustion monitoring unit (134) which receives a signal of the combustion pressure applied from the combustion pressure sensor (14) of each cylinder, captures a knock related pressure signal and transmits it to the main control panel Knock control device of dual fuel engine. A knocking signal is input when monitoring the sensing signal input from the knock sensor 12 and the combustion pressure sensor 14 installed in the cylinder (step S501);
Stopping the gaseous fuel operation mode when the knock level is equal to or greater than a preset knock limit value (step S503);
(Step S504), when the knock level is lower than a preset knock limit value, the knock canceling process is performed by controlling the combustion related factor by a preset knock cancel option;
And a step (S505) of continuing the knock canceling process until the knock signal disappears from the signal input from the knocking sensor (12) and the combustion pressure sensor (14) by the knock removing process (step S505) A method for knocking control of an engine. The method of claim 3,
As the knock removal processing method, there is a method in which the pilot injection timing is controlled to adjust the ignition timing, or the gas fuel injection duration (DOI) is controlled to adjust the gas fuel amount, or the pilot injection timing and the gas fuel injection duration (DOI) Wherein the knocking control is performed in parallel. 5. The method of claim 4,
Wherein said pilot injection timing adjustment for knock elimination is such that the pilot injection timing is delayed. 5. The method of claim 4,
Wherein the adjustment of the gas fuel injection duration (DOI) for knock removal reduces the gas fuel injection duration (DOI).

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