KR20140127451A - Cylinder balancing system and method method ushing maximum combustion pressure of dual fuel engine - Google Patents

Abstract

The present invention relates to a cylinder balancing device using the control of maximum combustion pressure of a dual fuel engine using oil and gas, and to a method thereof. The method of the present invention comprises the following steps of: (S501) receiving a sensing signal for combustion pressure from combustion pressure sensors (12) of each cylinder; (S502) calculating maximum combustion pressure (Pmax) of each cylinder from information on combustion pressure of the cylinder; (S503) determining whether Pmax of each cylinder reaches a target pressure (Pmax-limit); (S504) comparing Pmax and Pmax-limit of each cylinder and determining whether Pmax values of all cylinders reach the Pmax-limit; and (S505 or S605) advancing and delaying the timing of pilot injection when there is a cylinder whose Pmax does not reach the Pmax limit until the Pmax value of the cylinder reaches the Pmax-limit or extending or shortening the duration of injection (DOI) of gas. When the Pmax values of all cylinders reach the Pmax-limit, the final controlled timing of pilot injection is maintained.

Description

TECHNICAL FIELD [0001] The present invention relates to a cylinder balancing apparatus and method using a combustion maximum pressure control of a dual fuel engine,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to cylinder balancing of a dual fuel engine using an oil fuel and a gaseous fuel, and more particularly, to a combustion engine for a dual fuel engine which performs cylinder balancing by adjusting a combustion maximum pressure among combustion characteristic parameters in a gas fuel operation mode To a cylinder balancing apparatus and method using maximum pressure control.

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.

The dual-fuel engine (diesel engine) has a gas fuel operating mode using gaseous fuel and an oil fuel operating mode using oil fuel (e.g., Marine Diesel Oil, Heavy Fuel Oil, etc.) In the mixed operation mode.

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.

In the dual fuel engine as described above, a separate supply system must be provided for supplying the two main fuel and pilot oil, and the apparatus must be operated in two operation modes or more, The control system is also very complicated.

In particular, precise operating control in the gas fuel mode is a very important factor in determining whether or not the dual fuel engine can operate in the gas fuel mode, since the dual fuel engine is based on a diesel engine and allows further use of the gaseous fuel.

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 for the gaseous fuel.

For this reason, even when the ignition timing by the gaseous fuel is set to be the same in the gaseous fuel operation mode, the combustion (explosion) progression, the maximum pressure, and the point of time when the maximum pressure is generated differ from cylinder to cylinder.

Therefore, in the above-described dual fuel engine, it is advantageous to control the combustion characteristics and the combustion pressure between the cylinders to be uniform and high in order to stably maintain the operating characteristics of the engine.

When the combustion characteristics and the combustion pressure are maintained uniformly, the operation is stable and the efficiency is increased. Further, when the combustion pressure is uniformly maintained, the output and efficiency are further improved.

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

The present invention has been developed in accordance with the above-mentioned needs, and it is an object of the present invention to provide an apparatus and a method for controlling the combustion efficiency of a dual fuel engine in a gas fuel mode, And to provide a cylinder balancing apparatus and method using a combustion maximum pressure control of a dual fuel engine capable of maximizing a combustion efficiency.

In order to achieve the above object, a cylinder balancing apparatus using combustion maximum pressure control of a dual fuel engine according to the present invention is an engine control system for a dual fuel engine using oil fuel and gaseous fuel, A combustion pressure sensor for sensing the combustion pressure; An oil fuel injector for injecting an oil fuel into the combustion chamber; A pilot injector for injecting pilot fuel; A gas inflow valve for injecting gaseous fuel into the intake port; An injection control panel connected to the pilot injector and the gas inlet valve to control the operation; A combustion monitoring unit connected to the combustion pressure sensor and receiving a signal of the combustion pressure for each cylinder from the combustion pressure sensor to calculate a combustion maximum pressure Pmax of each cylinder; The combustion maximum pressure Pmax transmitted from the combustion monitoring unit is compared with a preset target pressure Pmax-limit and the combustion maximum pressure Pmax of all the cylinders is compared with the target pressure Pmax- control signal for advancing or retarding the pilot injection timing, or advancing or retarding the timing of starting the gas fuel injection to generate a control signal for extending or shortening the gaseous fuel injection duration (DOI) And a main control panel for causing the injection control panel to send the generated control signal to the injection control panel to adjust the pilot injector and the gas inlet valve.

In the cylinder balancing apparatus using the combustion maximum pressure control of the dual fuel engine according to the present invention, the combustion monitoring unit is provided in a cylinder monitoring panel which is separated from the main control panel and installed independently.

A method for balancing a cylinder in a gaseous fuel operation mode of a dual fuel engine according to an embodiment of the present invention includes: receiving a sensing signal for a combustion pressure from combustion pressure sensors of each cylinder (step S501); Calculating the maximum combustion pressure Pmax of each cylinder from the combustion pressure information of each cylinder (step S502); A process of determining whether the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S503); (Step S504) of comparing the maximum combustion pressure Pmax of the respective cylinders with the target pressure Pmax-limit to determine whether the maximum combustion pressure Pmax of all the cylinders reaches the target pressure Pmax-limit; When there is a cylinder in which the combustion maximum pressure Pmax has not reached the target pressure Pmax-limit, the pilot injection timing is changed until the combustion maximum pressure Pmax of the cylinder reaches the target pressure Pmax-limit A step of advancing or retarding (step S505); And a step S506 of maintaining the final pilot injection timing adjustment value at that time when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit.

In this case, the target pressure Pmax-limit is a predetermined upper limit value and a lower limit value based on the average combustion maximum pressure Pmax-average, which is the average value Pmax-average of the combustion maximum pressures Pmax calculated from the respective cylinders Is set to a pressure range in which a lower limit value is set or a pressure range in which a lower limit value of a predetermined range is limited based on a limit pressure that is the maximum pressure that the cylinder can reach in normal operation.

If the combustion maximum pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit in step S505, the pilot injection timing is advanced; When the maximum combustion pressure Pmax of a certain cylinder is higher than the target pressure Pmax-limit, the pilot injection timing is retarded.

A method of balancing cylinders in a gaseous fuel operation mode of a dual fuel engine according to another embodiment of the present invention includes: receiving a sensing signal from combustion pressure sensors of each cylinder (step S601); Calculating the maximum combustion pressure Pmax of each cylinder from the combustion pressure information of each cylinder (step S602); A process of determining whether the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S603); (Step S604) of comparing the maximum combustion pressure Pmax of the respective cylinders with the target pressure Pmax-limit to determine whether the maximum combustion pressure Pmax of all the cylinders reaches the target pressure Pmax-limit; When there is a cylinder in which the combustion maximum pressure Pmax has not reached the target pressure Pmax-limit, the cylinder pressure Pmax of the cylinder is increased until the combustion maximum pressure Pmax of the cylinder reaches the target pressure Pmax- A step of extending or shortening the gaseous fuel injection duration (DOI) step by step by advancing or retarding the start timing of the gaseous fuel injection (step S605); And maintaining the final gaseous fuel injection duration (DOI) adjustment value when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit (step S606).

In this case, the target pressure Pmax-limit is a predetermined upper limit value and a lower limit value based on the average combustion maximum pressure Pmax-average, which is the average value Pmax-average of the combustion maximum pressures Pmax calculated from the respective cylinders Is set to a pressure range in which a lower limit value is set or a pressure range in which a lower limit value of a predetermined range is limited based on a limit pressure that is the maximum pressure that the cylinder can reach in normal operation.

If the combustion maximum pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit at step S605, the gas fuel injection duration DOI is extended; If the combustion maximum pressure Pmax of a cylinder is higher than the target pressure Pmax-limit, the gaseous fuel injection duration (DOI) is shortened.

According to the cylinder balancing apparatus and method using the combustion maximum pressure control of the dual fuel engine according to the present invention, the combustion maximum pressure difference between the cylinders is regulated to a minimum range and the average combustion maximum pressure is maintained in a very high range.

Therefore, the combustion pressure between the cylinders becomes uniform, the conversion into the rotational force becomes smooth, the operation is stably maintained, and the output and efficiency are increased.

Also, the gas fuel operation mode of the dual fuel engine based on the diesel engine can be smoothly and satisfactorily performed, thereby improving the reliability.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the entire configuration of a cylinder balancing system using combustion maximum pressure control of a dual fuel engine according to the present invention; FIG.
Figure 2 is a schematic diagram of cylinder balancing control elements in accordance with the present invention;
FIG. 3 is a flowchart for explaining a control process for controlling balancing by controlling the maximum combustion pressure according to the first embodiment of the present invention.
4 is a chart showing engine initial states for performance testing for cylinder balancing control according to the present invention.
5 is a chart showing a result of performing cylinder balancing according to the first embodiment of the present invention.
FIG. 6 is a graph showing changes in average combustion maximum pressure and maximum pressure deviation according to the cylinder balancing according to the first embodiment of the present invention.
7 is a graph showing a change in efficiency according to the cylinder balancing according to the first embodiment of the present invention.
FIG. 8 is a flowchart illustrating a control process of controlling balancing by controlling the maximum combustion pressure according to the second embodiment of the present invention.
9 is a chart showing the result of performing cylinder balancing according to the second embodiment of the present invention.
10 is a graph showing changes in average combustion maximum pressure and maximum pressure deviation according to the cylinder balancing according to the second embodiment of the present invention.
11 is a graph showing a change in efficiency according to the cylinder balancing according to the second embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a cylinder balancing apparatus and method using combustion maximum pressure control of a dual fuel engine according to the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the entire configuration of a cylinder balancing system using combustion maximum pressure control of a dual fuel engine according to the present invention; FIG.

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 .

For cylinder balancing, a combustion pressure sensor 12 is installed in each cylinder (i.e., combustion chamber) of the dual fuel engine 10 to sense the combustion pressure. Further, a knock sensor 14 for knock control is provided.

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 gas fuel supply line 30 connected to the gas inlet valve 26 is provided with a gas valve unit 32 having a pressure regulator for regulating the pressure of the gaseous fuel, And a gas fuel pressure sensor 34 for detecting the gas fuel pressure.

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), fuel injection, etc., 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 operation according to the present invention.

The main control panel 100 receives the gas fuel pressure of the gas fuel supply line 30 from the gas fuel pressure sensor 34 and controls the pressure regulator of the gas valve unit 32 during the cylinder balancing control, Adjust the fuel supply pressure.

The main control panel 100 controls the 'pilot injection timing' or the 'gas injection duration (DOI)' for cylinder balancing, as will be described later in detail. This overall and individual adjustment signal is sent to the injection control panel 120 to allow the injection control panel 120 to control the pilot injector 24 and the gas inlet valve 26.

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 and controls them under the control of the main control panel 100.

A cylinder monitoring function (program or module) may be mounted together with the main controller 100 in order to receive the combustion information from the combustion pressure sensor 12 and the knock sensor 14 and to perform cylinder balancing control corresponding thereto.

In this embodiment, a separate cylinder monitoring panel 130 is provided for easier control.

The cylinder monitoring panel 130 is connected to the combustion pressure sensor 12 and the knock sensor 14. The cylinder monitoring panel 130 receives and receives cylinder combustion pressure information and knock information from the combustion pressure sensor 12 in real time, (Pmax), etc., and transmits the information to the main control panel 100.

The main control panel 100 performs a cylinder balancing control option and a knock control option that are input in advance based on data (e.g., combustion related parameter information and note information, etc.) transmitted from the cylinder monitoring panel 130. [

2 is a schematic diagram of cylinder balancing control elements of a dual fuel engine in accordance with the present invention; Please refer to Fig. 1 in parallel.

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

The combustion monitoring unit 132 receives a signal for each cylinder combustion pressure from the combustion pressure sensor 12 to generate a pressure change graph or calculates a combustion maximum pressure Pmax for each cylinder, And displays it on the monitoring PC 150 while transmitting it to the main control panel 100.

The knocking monitoring unit 134 receives a signal for each cylinder knock condition from the knock sensor 14, 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 ).

Programs for cylinder balancing and knock control are preset in the main control panel 100. [ Therefore, the main control panel 100 can control the operation of the cylinder monitoring panel 130 based on the information on the combustion maximum pressure Pmax transmitted from the combustion monitoring unit 132 of the cylinder monitoring panel 130, A control signal for offsetting the pilot injection timing or the gas fuel injection duration is generated for the injection control panel 120 to control the pilot injector 24 and the gas inflow valve 26.

[Cylinder balancing method by control of maximum combustion pressure (Pmax)] [

One of the cylinder balancing methods by the control of the maximum combustion pressure Pmax according to the present invention is to control the pilot oil fuel injection timing of the pilot injector 24 (see FIG. 1), that is, the pilot injection timing, (i.e., advancing or retarding the cylinder) to control the combustion maximum pressure Pmax of each cylinder to be kept high and uniform (first embodiment). The offset range of the general pilot injection timing, that is, the pilot injection timing adjustment range, is preliminarily set, 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, when the pilot injection timing is advanced, the ignition timing advances. When the timing is retarded, the ignition timing is retarded. When the pilot injection timing is adjusted within the limited offset 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 retarded When the ignition timing is delayed, the maximum combustion pressure (Pmax) tends to decrease.

Next, the opening time of the gas inflow valve 26, that is, the duration of injection of the gaseous fuel (DOI) is offset (i.e., extended or shortened) to increase the maximum combustion pressure Pmax of each cylinder (Second embodiment). The offset range of the injection duration (DOI) of the gaseous fuel, that is, the increase / decrease range of the injection duration (DOI), is preset to a limited range. The extension of the gaseous fuel injection duration is performed by advancing the injection start timing without changing the gaseous fuel injection termination timing. Thus, the duration of the gas fuel injection is prolonged and the gas inflow of the cylinder increases and the maximum combustion pressure Pmax increases. Further, the reduction in the duration of the gaseous fuel injection is performed by perceiving the injection start timing without changing the gaseous fuel injection end timing. Thus, the duration of the gas fuel injection is shortened and the gas inflow of the cylinder is reduced and the maximum combustion pressure (Pmax) is reduced.

≪ Example 1 >

3 is a flowchart illustrating a process of controlling the maximum combustion pressure Pmax of each cylinder by offsetting the pilot injection timing according to the first embodiment of the present invention.

Referring to FIG. 3, when a sensing signal is input from the combustion pressure sensors 12 of each cylinder (step S501), the combustion maximum pressure Pmax of each cylinder is calculated (step S502).

The maximum combustion pressure (Pmax) is the maximum value of the pressure generated during the combustion stroke. The calculation of the combustion maximum pressure (Pmax) produces and extracts, for example, a pressure-time diagram for the combustion pressure.

Then, it is determined whether or not the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S503).

Here, the target pressure Pmax-limit can be set to a predetermined pressure range in which the upper limit value and the lower limit value are specified based on the average value (Pmax-average) of the combustion maximum pressures Pmax of the respective cylinders. When the target pressure Pmax-limit is set and controlled by the average value of the combustion maximum pressure Pmax, i.e., the average combustion maximum pressure Pmax-average, the combustion maximum pressure Pmax of each cylinder becomes uniform, The maximum pressure deviation (Max - Min) of the combustion maximum pressure value between the combustion chambers is reduced and the efficiency is increased and the operation stability is improved.

Further, the target pressure Pmax-limit may be set to a pressure range in which a lower limit value of a certain range is limited based on a maximum pressure (reachable) that the cylinder can exhibit in normal operation. Therefore, the target pressure in this case is close to the maximum pressure (i.e., the limit pressure) that the cylinder can exert. In the case where the target pressure Pmax-limit is set to the limit pressure range of the cylinder, the average combustion maximum pressure Pmax-average of the cylinders is raised to be close to the limit pressure, and at the same time, the maximum pressure deviation Max- It is very advantageous to maximize the efficiency, the operation stability and the output.

After determining that the combustion maximum pressure Pmax of each cylinder has reached the target pressure Pmax-limit, the combustion maximum pressure Pmax of each cylinder is compared with the target pressure Pmax-limit, It is determined whether or not the maximum combustion pressure Pmax of the cylinders has reached the target pressure Pmax-limit (step S504).

When there is a cylinder in which the combustion maximum pressure Pmax has not reached the target pressure Pmax-limit, the pilot pressure Pmax is increased until the combustion maximum pressure Pmax of the cylinder (s) reaches the target pressure Pmax- The operation of advancing or retarding the injection timing based on the preset control procedure is performed step by step (step S505). For example, when the maximum combustion pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit, the pilot injection timing is advanced. This can increase the ignition timing and increase the maximum combustion pressure (Pmax). Conversely, if the maximum combustion pressure Pmax of a certain cylinder is higher than the target pressure Pmax-limit, control is performed to retard the pilot injection timing. This can slow the ignition timing and reduce the maximum combustion pressure (Pmax).

Thus, when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit, it is continuously maintained at the final pilot injection timing adjustment value at that time (step S506).

If a control end signal is input for some reason in the engine control system, the final control value is stored and control is terminated (step S507).

<Engine Early Condition and Test Results for Testing the First Embodiment>

4 is a chart showing engine initial states for performance testing for cylinder balancing control according to the present invention.

Referring to FIG. 4, the initial set values and conditions of the engine to be used in the cylinder balancing control test are as follows.

Engine load: 100%,

Global ignition timing: 14 ° crs before crank angle (crank angle)

Boost pressure: 4.40 barA

Exhaust gate position: about 39%

5 is a chart showing a result of performing cylinder balancing according to the first embodiment of the present invention.

5, when the cylinder balancing control is not performed (Meas_1), the cylinder having the maximum value (Max-Value) of the combustion maximum pressure Pmax among the cylinders has a pressure of 155 bar and a min- Is very large because the pressure is 142 bar and the maximum pressure deviation (Max - Min) is 13 bar.

Therefore, when the cylinder balancing control is not performed, the operation stability is degraded and the efficiency is as low as 45.09%. In addition, the average value (Pmax-average) of the maximum combustion pressure Pmax of the cylinders is 148.9 bar, which is somewhat insufficient for the performance that the engine can exert.

If the cylinder balancing control option is executed to set the total pilot injection timing to 14 (crs BTDC) and set the target pressure Pmax-limit to the average combustion maximum pressure Pmax-average calculated from the engine under drive (Meas_2) in which the pilot injection timing is adjusted so that the combustion maximum pressure Pmax of each cylinder reaches the target pressure Pmax-limit, the average combustion maximum pressure Pmax-average does not change to 149 bar, As the deviation (Max - Min) is 2bar, it is remarkably reduced as compared with 13bar at the time of uncontrolled, and all the cylinders show a uniform output, thereby improving the operation stability and increasing the efficiency to 45.17.

If the pilot injection timing is adjusted so that the cylinder maximum pressure Pmax of each cylinder reaches the target pressure Pmax-limit by setting the target pressure Pmax-limit to the limit pressure by executing the cylinder balancing control option (Meas_3), the maximum pressure deviation (Max - Min) is reduced to 2 bar to improve the stability. In addition, the average combustion maximum pressure (Pmax-average) also greatly increases to 157.1, which greatly increases the engine output. In addition, due to the above effects, the efficiency is further improved to 45.41.

FIG. 6 is a graph showing changes in the average combustion maximum pressure (Pmax-average) and the maximum pressure deviation before and after the control based on the results shown in FIG. FIG. 7 is a graph showing the change in efficiency due to cylinder balancing before and after the control.

As can be seen from FIG. 6 and FIG. 7 and as already known from the description of FIG. 5, compared with the case where the cylinder balancing is not performed (indicated by "no balancing" in the figure) When the maximum pressure Pmax is controlled (indicated by 'active balancing @ 14 ° BTDC' and 'active balancing @ 16 ° BTDC'), the average combustion maximum pressure (Pmax- And the maximum pressure deviation (Max - Min) (indicated by 'Max - Min (bar)' in the figure) is greatly reduced and the efficiency is improved.

&Lt; Example 2 >

FIG. 8 is a view for explaining a cylinder balancing process according to a second embodiment of the present invention.

The cylinder balancing according to the second embodiment of the present invention is a method of controlling so as to offset (i.e., extend or shorten) the injection duration (DOI) of the gaseous fuel so that the combustion maximum pressure Pmax of each cylinder is kept high and uniform to be.

Referring to FIG. 8, when a sensing signal is inputted from the combustion pressure sensors 12 of each cylinder (step S601), the combustion maximum pressure Pmax of each cylinder is calculated (step S602).

The calculation of the combustion maximum pressure (Pmax) is the maximum value of the pressure generated during the combustion stroke. The calculation of the combustion maximum pressure (Pmax) produces and extracts, for example, a pressure-time diagram for the combustion pressure.

Then, it is determined whether or not the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S603).

Here, the target pressure Pmax-limit can be set to a predetermined pressure range in which the upper limit value and the lower limit value are specified based on the average value (Pmax-average) of the combustion maximum pressures Pmax of the respective cylinders. When the target pressure Pmax-limit is set and controlled by the average value of the combustion maximum pressure Pmax, i.e., the average combustion maximum pressure Pmax-average, the combustion maximum pressure Pmax of each cylinder becomes uniform, The maximum pressure deviation (Max - Min) of the combustion maximum pressure value between the combustion chambers is reduced and the efficiency is increased and the operation stability is improved.

Further, the target pressure Pmax-limit may be set to a pressure range in which a lower limit value of a certain range is limited based on a maximum pressure (reachable) that the cylinder can exhibit in normal operation. Therefore, the target pressure in this case is close to the maximum pressure (i.e., the limit pressure) that the cylinder can exert. In the case where the target pressure Pmax-limit is set to the limit pressure range of the cylinder, the average combustion maximum pressure Pmax-average of the cylinders is raised to be close to the limit pressure, and at the same time, the maximum pressure deviation Max- It is very advantageous to maximize the efficiency, the operation stability and the output.

After determining that the combustion maximum pressure Pmax of each cylinder has reached the target pressure Pmax-limit, the combustion maximum pressure Pmax of each cylinder is compared with the target pressure Pmax-limit, It is determined whether or not the maximum combustion pressure Pmax of the cylinders has reached the target pressure Pmax-limit (step S604).

When there is a cylinder in which the combustion maximum pressure Pmax has not yet reached the target pressure Pmax-limit, the combustion maximum pressure Pmax of the cylinder (s) reaches the target pressure Pmax- The operation of advancing or retarding the start of the gas fuel injection of the cylinder based on a predetermined control procedure is performed step by step to extend or shorten the duration of the gas fuel injection duration (step S605).

If the gas fuel injection duration (DOI) is extended, the gas inflow to the cylinder increases and the maximum combustion pressure Pmax increases. On the contrary, if the gas fuel injection duration (DOI) is shortened, the gas inflow amount to the cylinder decreases and the maximum combustion pressure Pmax decreases.

For example, if the maximum combustion pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit, control is performed to extend the gas fuel injection duration DOI. The maximum combustion pressure (Pmax) can then be increased. Conversely, if the maximum combustion pressure Pmax of a certain cylinder is higher than the target pressure Pmax-limit, control is performed to shorten the gaseous fuel injection duration DOI. The combustion maximum pressure (Pmax) can then be reduced.

Thus, when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit, it is continuously maintained at the then-final gas fuel injection duration (DOI) adjustment value (step S606).

If a control end signal is input for some reason in the engine control system, the final control value is stored and control is terminated (step S607).

9 is a chart showing the result of performing cylinder balancing according to the second embodiment of the present invention.

Referring to FIG. 9, when the cylinder balancing control is not performed (the first Meas_1 in the left hand side), the cylinder showing the maximum value of the combustion maximum pressure Pmax is 155 bar and the minimum value Min -Value) is very large because the pressure is 140 bar and the maximum pressure deviation (Max-Min) is 15 bar.

Therefore, when the cylinder balancing control is not performed, the operation stability is degraded and the efficiency is as low as 44.93%. In addition, the average value (Pmax-average) of the maximum combustion pressure Pmax of the cylinders is 148.9 bar, which is somewhat insufficient for the performance that the engine can exert.

If the cylinder balancing control option is executed to set the gas fuel injection start timing of the entire cylinder at 14 (crs BTDC) and set the target pressure Pmax-limit to the average combustion maximum pressure Pmax- average (the second Meas_1 from the left), the gas fuel injection duration (DOI) is adjusted so that the maximum combustion pressure Pmax of each cylinder reaches the target pressure Pmax-limit, (Pmax-average) is 148.7 bar, but the maximum pressure deviation (Max-Min) is 1 bar, which is significantly reduced compared with the control pressure of 15 bar, so that all the cylinders show a uniform output, The efficiency also increases to 45.03.

Next, the cylinder balancing control option is executed to set the gas fuel injection start timing of the entire cylinder to 16 (° crs BTDC), set the target pressure (Pmax-limit) to the limit pressure, When the gas fuel injection duration (DOI) is adjusted so that the pressure Pmax reaches the target pressure Pmax-limit (Meas_2 from the left), the maximum pressure deviation (Max-Min) is reduced to 1 bar to improve stability . In addition, the average combustion maximum pressure (Pmax-average) also greatly increases to 157.6, which greatly increases the engine output. In addition, due to the above effects, the efficiency is further improved to 45.46.

Next, the cylinder balancing control option is executed to set the gas fuel injection start timing of the entire cylinder to 16.5 (° crs BTDC), set the target pressure (Pmax-limit) to the limit pressure, When adjusting the gas fuel injection duration (DOI) so that the pressure (Pmax) reaches the target pressure (Pmax-limit) (the second Meas_2 from the left), the maximum pressure deviation (Max - Min) . In addition, the maximum combustion maximum pressure (Pmax-average) also increases to 159.3 to maximize the engine output. Also, due to the above effects, the efficiency is further improved to 45.55.

FIG. 10 is a graph showing changes in the average combustion maximum pressure (Pmax-average) and the maximum pressure deviation before and after the control based on the results shown in FIG. 11 is a graph showing a change in efficiency due to cylinder balancing before and after control.

As can be seen from FIGS. 10 and 11 and as already known from the description of FIG. 9, compared with the case where the cylinder balancing is not performed (indicated by "no balancing" in the figure) When controlling the maximum pressure Pmax (indicated as 'active balancing @ 14 ° BTDC', 'active balancing @ 16 ° BTDC' and 'active balancing @ 16.5 ° BTDC'), the average combustion maximum pressure (Pmax-average (Shown as 'Average (bar)' in the figure) increases and the maximum pressure deviation (Max - Min) (shown as 'Max - Min (bar)' in the figure) is greatly reduced and efficiency is improved.

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: Combustion pressure sensor
14: Knock sensor
20: Cylinder head
22: Oil fuel injector
24: Pilot injector
26: Gas inlet valve (GAV)
30: Gas fuel supply line
32: gas valve unit 32
34: Gas Fuel Pressure Sensor (34)
100: Main control panel
110: Local operating panel
120: Injection control panel
130: Cylinder monitoring panel
132: Combustion monitoring unit
134: Knock monitoring unit

Claims (8)

An engine control system for a dual fuel engine using oil fuel and gaseous fuel,
A combustion pressure sensor (12) installed in each cylinder to sense the combustion pressure;
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;
An injection control panel 120 connected to the pilot injector 24 and the gas inlet valve 26 to control the operation thereof;
A combustion monitoring unit (132) connected to the combustion pressure sensor (12) and receiving signals from the combustion pressure sensor (12) for each cylinder combustion pressure to calculate a combustion maximum pressure (Pmax) value of each cylinder; And
The combustion maximum pressure Pmax transmitted from the combustion monitoring unit 132 is compared with a preset target pressure Pmax-limit and the combustion maximum pressure Pmax of all the cylinders is compared with the target pressure Pmax A control signal for advancing or retarding the pilot injection timing until the fuel injection timing is reached, or a control signal for extending or shortening the gaseous fuel injection duration (DOI) by advancing or retarding the timing of starting the gas fuel injection, And a main control panel 100 for causing the injection control panel 120 to adjust the pilot injector 24 and the gas inlet valve 26 by generating the control signal to the injection control panel 120 Wherein the cylinder-balancing device is a cylinder-balancing device. The method according to claim 1,
Wherein the combustion monitoring unit (132) is provided in a cylinder monitoring panel (130) separated from the main control panel (100) and independently installed. A method of balancing a cylinder in a gaseous fuel operating mode of a dual fuel engine,
Receiving a sensing signal for the combustion pressure from the combustion pressure sensors 12 of each cylinder (step S501);
Calculating the maximum combustion pressure Pmax of each cylinder from the combustion pressure information of each cylinder (step S502);
A process of determining whether the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S503);
(Step S504) of comparing the maximum combustion pressure Pmax of the respective cylinders with the target pressure Pmax-limit to determine whether the maximum combustion pressure Pmax of all the cylinders reaches the target pressure Pmax-limit;
When there is a cylinder in which the combustion maximum pressure Pmax has not reached the target pressure Pmax-limit, the pilot injection timing is changed until the combustion maximum pressure Pmax of the cylinder reaches the target pressure Pmax-limit A step of advancing or retarding (step S505); And
(Step S506) of maintaining the final pilot injection timing adjustment value at that time when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit Cylinder balancing method using maximum pressure control. The method of claim 3,
The target pressure (Pmax-limit)
(Pmax-average), which is an average value (Pmax-average) of the combustion maximum pressures (Pmax) calculated from the respective cylinders being driven, or a pressure range in which a predetermined upper limit value and a lower limit value are specified,
Wherein the cylinder is set to a pressure range in which a lower limit value of a predetermined range is limited based on a limit pressure which is a maximum pressure reachable by the cylinder during normal operation. The method of claim 3,
In step S505, if the maximum combustion pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit, the pilot injection timing is advanced,
Wherein when the maximum combustion pressure Pmax of a certain cylinder is higher than the target pressure Pmax-limit, the pilot injection timing is retarded, and the cylinder balancing method using the combustion maximum pressure control of the dual fuel engine. A method of balancing a cylinder in a gaseous fuel operating mode of a dual fuel engine,
A step of receiving a sensing signal from the combustion pressure sensors 12 of each cylinder (step S601);
Calculating the maximum combustion pressure Pmax of each cylinder from the combustion pressure information of each cylinder (step S602);
A process of determining whether the maximum combustion pressure Pmax of each cylinder has reached the target pressure Pmax-limit (step S603);
(Step S604) of comparing the maximum combustion pressure Pmax of the respective cylinders with the target pressure Pmax-limit to determine whether the maximum combustion pressure Pmax of all the cylinders reaches the target pressure Pmax-limit;
When there is a cylinder in which the combustion maximum pressure Pmax has not reached the target pressure Pmax-limit, the cylinder pressure Pmax of the cylinder is increased until the combustion maximum pressure Pmax of the cylinder reaches the target pressure Pmax- A step of extending or shortening the gaseous fuel injection duration (DOI) step by step by advancing or retarding the start timing of the gaseous fuel injection (step S605); And
(Step S606), when the combustion maximum pressure Pmax of all the cylinders reaches the target pressure Pmax-limit, maintaining the final gaseous fuel injection duration (DOI) adjustment value at that time A cylinder balancing method using combustion maximum pressure control of a dual fuel engine. The method according to claim 6,
The target pressure (Pmax-limit)
(Pmax-average), which is an average value (Pmax-average) of the combustion maximum pressures (Pmax) calculated from the respective cylinders being driven, or a pressure range in which a predetermined upper limit value and a lower limit value are specified,
Wherein the cylinder is set to a pressure range in which a lower limit value of a predetermined range is limited based on a limit pressure which is a maximum pressure reachable by the cylinder during normal operation. The method according to claim 6,
In step S605, if the combustion maximum pressure Pmax of a certain cylinder is lower than the target pressure Pmax-limit, the gas fuel injection duration DOI is extended,
Wherein the gas fuel injection duration (DOI) is shortened if the maximum combustion pressure Pmax of a certain cylinder is higher than the target pressure Pmax-limit.

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