JPH0511211B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a main engine control method for minimizing fuel consumption per voyage. A ship encounters a variety of sea conditions during its voyage, and even if the average speed for a voyage is the same, the fuel consumption for a voyage will vary depending on how the speed is chosen in each sea condition. In the past, humans adjusted the set rotation speed of the main engine governor so that the main engine's output remained approximately constant even when sea conditions changed. However, even if the output of the main engine can be held constant, such control does not necessarily minimize the total fuel consumption for one voyage. This invention proposes an optimal control method for the main engine that is completely different from conventional methods. The main engine control method for a ship according to the present invention involves minutely changing the rotational speed of the main engine at certain intervals during a voyage, and changing the ship speed Δx and the main engine fuel consumption per unit time due to the change in the rotational speed. Measure Δy, compare the ratio of both Δy/Δx with the target value,
If Δy/Δx is smaller than the target value, the rotation of the main engine is increased, and if it is larger than the target value, the rotation is decreased.
The principle of this invention, which is characterized by controlling the main engine so that there is no difference between Δy/Δx and a target value, will be explained with reference to FIG. Let us now assume that the speed-fuel consumption (per unit time) curve in sea condition I is curve I in FIG. 1, and is expressed by y=f ₁ (x) and y=f ₂ (x), respectively. If the combination of economic speeds is curve I and points a ₁ and a ₂ on it, then (dy/dx) _x=x1 = (dy/dx) _x=x2 must be satisfied. This is because, at the speed combination point, if (dy/dx) _x=x1 > (dy/dx) _x=x2 , then each minute time Δt in sea state I,
When the minute speed Δx is decelerated by sea condition I and accelerated by sea condition I, at the same average speed, (dy/dx) _x=x1・Δx・Δt −(dy/dx) _x=x2・Δx・Δt> The fuel consumption can be reduced by 0, and this combination is not the one that minimizes the fuel consumption. Additionally, fuel consumption per unit time can generally be approximated by three dimensions of speed, and as the speed increases, dy/dx increases, and due to the above speed increase, finally (dy/dx) _x=x1 = (dy/dx) _x=x2 can be set. However, using the above method, if you decelerate due to sea condition I and speed up due to sea condition I, even though the average speed is the same, the cruising distance in sea condition I will decrease by Δx・Δt, the distance in sea condition I will decrease, and The distance will increase. When comparing the total fuel consumption of one voyage, there is a difference between a constant speed (dy/dx) and a speed that truly minimizes fuel consumption (economic speed) by the amount of stacking of Δx and Δt. There is an example of the difference in total fuel consumption at that time. Specifically, finding Δy/Δx at the ship's operating point and making it equal to the target dy/dx can be done as follows.
Once the ship leaves the port and enters the state of steady voyage, small changes ΔN in the main engine rotation speed N occur periodically, for example every 15 minutes.
(for example, 0.5 to 1.0 rpm). In this case, fuel consumption per unit time changes instantaneously,
The ship's speed changes after a certain run-up period. After the run-up period (for example, 10 minutes) has elapsed, the fuel consumption and speed per unit time are measured, and Δy/Δx is calculated from the difference in fuel consumption per unit time (Δy) and speed difference (Δx) before and after the slight change is made. If Δy/Δx>target dy/dx, increase the speed by ΔN and make (N+ΔN) the new target rotation speed. Since the instantaneous values of fuel consumption and speed per unit time fluctuate over a considerable range, after the run-up period,
It is necessary to measure a sufficient number of times and average the measured values. Fuel consumption per unit time can be measured by the following method. Method using shaft horsepower meter and main engine fuel consumption curve Method using main engine rotational speed and fuel pump rack reading Method using main engine fuel flow meter In addition, ship speed can be measured using a ship speed meter. Next, when operating at such constant dy/dx, compared to operating at economical speed (the speed that truly minimizes total fuel consumption) or operating at constant power, the cost per voyage is Let's calculate how much difference there will be in fuel consumption. Five sea conditions, I to V, are assumed to be encountered during one voyage, and the speed-fuel consumption curve and cruising distance in each sea condition are shown in FIG. Note that, except for sea condition I, which is flat water, each of the curves from sea condition to V does not pass through the zero point. This is because even if the ship's speed is zero, the resistance to the ship due to wind and waves does not become zero. The average speed is assumed to be 15 knots and 12 knots, and the calculation results for each case are shown in Tables 1 and 2.
is shown. From these tables, it can be seen that operation with constant dy/dx has a several percent lower cost than conventional operation with constant output, and there is almost no difference from operation using economic speed. In addition,
Total fuel consumption is the sum of the product of power and voyage time in each sea state. Since it is considered that the main engine output cannot be changed significantly on an actual ship, Table 1 shows the case where the ratio between the maximum and minimum output values is limited to 2:1.
It has been added to Table 2. It can be seen that when such a restriction is added, the difference in natural costs between operations with constant dy/dx and operations at economic speed becomes smaller.

【table】

【table】

[Table] Next, an example of an apparatus for implementing the present invention will be described based on the drawings. FIG. 3 is a schematic diagram of a conventional main engine control system, in which the rotation speed setting signal from the control handle 1 enters the relay panel 2 as a voltage signal or air pressure signal, and from the relay panel 2 the target rotation speed is transmitted to the main engine governor 3. Output as a signal. This device is installed between the control handle 1 and the relay panel 2 of this conventional main engine control device, and in the following explanation, the case where the rotation speed setting signal from the control handle 1 is a voltage signal will be described. If the same rotation speed setting signal is a pneumatic pressure signal, connect a pneumatic pressure/voltage converter to the input side of the rotation speed setting signal of this device, and a voltage/pneumatic pressure converter to the output side of this device to relay panel 2. establish. FIG. 4 shows the electronic control circuit of this device. In addition to the rotation speed setting signal a from the control handle, the ship speed signal b from the ship speedometer, the target dy/dx setting signal c, and the main engine FO
The pulse signal d every 50 from the flow meter, the ON/OFF signal e of the dy/dx control, the signals a and b pass through the A/D converters 4 and 5, and the signals c to e immediately go to the input port 6. is input. The input port 6 is composed of a multiplexer, receives a selection signal applied via a signal line 13 from the CPU 8, and selects a signal to be output to the CPU 8 from among the signals a to e. 10 is a microcomputer, basically
It consists of CPU8, RAM7, and ROM9.
A program to control the CPU 8 is written in the ROM 9, and the CPU 8 reads necessary external data from the input port 6 or exchanges data with the RAM 7 according to this program. While performing calculation processing, the processed data is output to the output port 11. The output port relays the data signal from the CPU 8 to the D/A converter 12, and after D/A conversion by the D/A converter 12, it is output to the relay panel 2 as the rotation speed setting signal f of this device. The microcomputer 10 has a built-in timer using the clock of the CPU 8 and the RAM 7, and each timer sends and receives the elapsed time after being reset to the CPU 8. Timer I Timer for timing the pulse signal interval from the main engine FO flowmeter Timer for timing the interval that gives minute speed changes Timer for timing the ship speed measurement interval The program written in CPU 8 is shown in a flowchart as shown in Figure 5. ~It will look like Figure 8. FIG. 5 shows the main flow of this program. When the program starts, in step 1, the timer I is reset and the timing of the intervals at which minute speed changes are applied is started. In step 2, the value Nin obtained by A/D converting the rotation speed setting signal a from the control handle 1 is stored in the memory in the RAM 7. In step 3, check whether the main engine FO flowmeter pulse is input to input port 6, and if yes, the FO
A branch is made to subroutine I for measuring flowmeter pulse intervals. Check the timer in step 4, determine if it is time to make a small speed change, and select yes.
If so, the timer is reset to start measuring the current ship speed, and the ship speed measurement counter C is reset. In step 5, the timer is checked and it is determined whether it is time to measure the ship's speed. If yes, the process branches to a subroutine for measuring the ship's speed and processing after measuring the ship's speed. In step 6, dy/dx control is currently ON/OFF
If it is OFF, the value Nout to the output port is rewritten to Nin in step 7, and if it is ON, the Nout processed by the subroutine is held. Step 8 goes to the output port
Output Nout and return to step 2. FIG. 6 shows the contents of subroutine I. In step 11, the elapsed time of timer I in RAM 7 is read. RAM 7 has 10 memories T(1) to T(10) for storing the FO flow meter pulse interval T. In step 12, the T read this time is entered in T(1), and T(2) is stored. T(1) for T(3), T(2) for T(N),
(N-1) is stored. Step 13 is the next FO
Prepare to measure the flow meter pulse interval, reset timer I, and return to the main flow. FIG. 7 shows the contents of the subroutine. RAM
7 is provided with a counter C for counting the number of ship speed measurements, and M memories V(1) to V(M) for storing ship speed measurements a predetermined number of times M. In step 21, the A/D conversion value V of the ship speed signal 5 is read from the input port 6. At step 22, add 1 to counter C. Store the ship speed V read in step 23 in memory V(C)
Store it in In step 24, it is determined whether the ship speed has been measured a specified number of times, and if yes, the process branches to a subroutine. In step 25, the timer is reset in preparation for the next ship speed measurement, and the process returns to the main flow. FIG. 8 shows the contents of the subroutine. RAM
7 is provided with memories X(2) and Y(2) for storing the average ship speed and average fuel consumption measured last time, and memories X(1) and Y(1) for storing the current measured values. In step 31, the average ship speed Vmean is calculated from the ship speed values M specified times. In step 32, the average value Tmean of the 10 FO flow meter pulse intervals is determined. In step 23, the proportionality constant K
and Tmean, fuel consumption per unit time FOC
seek. In step 34, the previously measured ship speed and fuel consumption per unit time are stored in X(2) and Y(2), and the currently measured ship speed and fuel consumption per unit time are stored in X(1) and Y(1). In step 35, Δy/Δx before and after the minute speed change is determined. In step 36, it is determined whether the Δy/Δx is larger than the target dy/dx,
If yes, go to step 37 and set the sign of the specified minute rotational speed change ΔN to negative; if no, proceed to step 37.
Add ΔN to Nout output to the output port in step 38. In step 39, the timer is reset to determine when to apply the next minute speed change, and the process returns to the subroutine. As explained above, this invention slightly changes the rotational speed of the main engine at certain intervals during a voyage, and calculates the change Δx in the ship and the change Δy in the main engine fuel consumption per unit time due to the change in the rotational speed. This method controls the main engine rotation speed so that the ratio Δy/Δx of both matches the target value. This has the effect of reducing fuel consumption.

[Brief explanation of drawings]

Figure 1 is a speed-fuel consumption curve for explaining the principle of this invention; Figure 2 is a model of a speed-fuel consumption curve assumed to compare the superiority of several main engine control methods; Figure 4 is a block diagram of a conventional main engine control system, Figure 4 is a block diagram of a device used to implement the present invention, Figure 5 is a flowchart of a program for operating the CPU shown in Figure 4, and Figure 6 is a block diagram of a conventional main engine control system.
FIG. 7 is a flowchart showing the contents of subroutine I in FIG. 5, and FIG. 8 is a flowchart showing the contents of the subroutine in FIG.

Claims (1)

[Claims] 1 During the voyage, the rotational speed of the main engine is slightly changed at certain intervals, and the change in ship speed Δx and the change in main engine fuel consumption per unit time Δy due to the change in rotational speed are calculated.
, and compare the ratio Δy/Δx of both with the target value. If Δy/Δx is smaller than the target value, increase the rotation of the main engine, and if it is larger than the target value, decrease the rotation, and Δy/Δx and target value. A method for controlling a main engine of a ship, characterized in that the main engine is controlled so as to eliminate the difference between the two.