JPS61252842A - Method of controlling main machinery of ship - Google Patents

Abstract

PURPOSE:To reduce a fuel consumption amount per one voyage, according to the method wherein a change in a ship speed and a fuel consumption amount per a unit hour are measured, and a main device is controlled so that a difference between a ratio between the change and fuel consumption amount and a desired value is decreased. CONSTITUTION:A RAM is provided with memories X(2) and Y(2), storing preceding measured mean ship speed and mean fuel consumption amount, and memories X(1) and Y(1) storing a present measured value. In a step 35, DELTAY/DELTAX before and after a fine change in speed is determined. In a step 36, it is decided whether DELTAY/DELTAX exceeds a desired dy/ds is or not, and in a step 38, DELTAN is added to Nout outputted to an output port. The number of revolutions of a main machinery is controlled so that DELTAY/DELTAX coincides with a desired value. This enables decrease of a fuel consumption amount per one voyage.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed 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 of the voyage is the same, the amount of fuel consumed during the 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 of 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 Δy/Δx of both with the target value, increase the rotation of the main engine if Δy/Δx is smaller than the target value, lower the rotation if it is larger than the target value, and adjust the ratio between Δy/Δx and the target value. The principle of this invention, which is characterized by controlling the main engine so as to eliminate the difference in values, will be explained with reference to FIG.

Now, the speed-fuel consumption (per unit time) curves under sea conditions ■ and ■ are combined with the curves ■ and ■ in Figure 1, respectively, and f = f.
<-L>, Lj=field χ). Curve the adjustment of economic speed! ,■If the point αlN aZ on Must be 2. This is because, at the speed combination point, if (I) If the speed is increased at ■, the fuel consumption can be reduced by an amount at the same average speed, and this combination is not the one that minimizes the fuel consumption.

In addition, in general, the amount of fuel consumed per unit time can be approximated by three dimensions of speed, and as the speed increases, dy/dx increases, which can be achieved by increasing the speed described above.

However, using the above method, if you decelerate due to sea condition ■ and speed up due to sea condition ■, even though the average speed is the same, the cruising distance under sea conditions r and n will decrease by Δx・Δt, and the distance under sea condition ■ will decrease by Δx・Δt. , marine phenomena■
The distance will increase. - When comparing the total fuel consumption of a 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 loading of Δx and Δt. There is an example of the difference in total fuel consumption at that time.

Specifically, find △y/△X of the ship's operating point and set it as the target d.
Setting it equal to y/dx can be done as follows. When the ship leaves the port and enters the state of steady voyage, quantitatively, for example, minute changes ΔN (for example, O15 to 1.
Orpm).

In this case, fuel consumption per unit time changes instantaneously, but ship 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 determined from the fuel consumption difference (Δy) and speed difference (Δx) per unit time before and after the slight change is made.

If Δy/Δx〉target dy/dx, increase speed by ΔN,
It is sufficient if (N+ΔN) is the new target rotation speed.

Since the instantaneous values of fuel consumption and speed per unit time fluctuate over a considerable range, it is necessary to measure them a sufficient number of times after the run-up period and average these 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 based on reading of main engine rotation speed and fuel bomb rack ■Method using main engine fuel flow meter In addition, ship speed can be measured using a ship speedometer.

Next, when operating at constant dy/dx in this way, compared to operating at economical speed (speed that truly minimizes total fuel consumption) or operating at constant output, -
Let's calculate how much difference there will be in fuel consumption during the voyage. - Five sea conditions I to (2) are assumed to be encountered during the voyage, and the speed-fuel consumption curve and cruising distance under each sea condition are shown in Figure 2. Note that, except for the sea condition (2), which is flat water, the curves of the sea conditions (2) to (V) do 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 16 knots and 12 knots, and the calculation results for each case are shown in Tables 1 and 2. From these tables, it can be seen that the natural cost of operation with constant dy/dx is several percent lower than the conventional operation with constant output, and there is almost no difference from the case of operation based on economic speed. Note that the total fuel consumption is the sum of the product of output and voyage time in each sea state.

Since it is conceivable that the main engine output cannot be changed significantly on an actual ship, the case where the ratio between the maximum value and the minimum value of the output is limited to 2:1 is added to Table 11 and Table 2.

It can be seen that when such a restriction is added, the difference in natural costs between constant dy/dx operation and economic speed operation becomes smaller.

Next, an example of an apparatus for implementing the present invention will be explained 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 l enters the relay panel 2 as a voltage signal or air pressure signal, and from the relay panel 2 to the main engine governor 3, the rotation speed setting signal is transmitted to the main engine governor 3. Output as a signal.

This device is installed between the control handle 1 of this conventional main engine control device and the relay panel 2, 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,
Target dy/dx setting signal c1 50 from main engine FO flowmeter
The pulse signal d for each pulse and the 0N10FF signal e under dy/dx control are passed through the A/D converter 4.5, and the signals a and b are converted to the signal C.
-e is directly input to the input port 6. The input boat 6 is composed of a multiplexer, and C
It receives a selection signal applied via the signal line 13 from the PU 8, and selects the signal to be output to the CPU 8 from among the signals a''-e.

10 is a microcomputer, basically CPU8,
RAM? , ROM9. ROM9 is C
A program to control PU8 is written, and CPt
According to this program, J8 imports necessary external data from input board 6 or stores it in RAM.
7. Performs arithmetic processing while exchanging data between the two, and outputs the processed data to the output port (■). The output port transfers the data signal from CPU8 to D.
/A converter 12, and after D/A conversion by the D/A converter 12, it is sent to the relay panel 2 as the rotation speed setting signal f of this device.
Output to.

The microcomputer 10 has a CPU 8 clock and RAM.
7 is built in, and each timer sends and receives the elapsed time after reset to the CPU 8.

Timer ■ Timer for measuring the pulse signal interval from the main engine FO flow meter ■ Timer for measuring the interval that gives minute speed changes ■ For measuring the ship speed measurement interval The program written in the CPU 8 is shown in the flowchart as No. 5. The result will be as shown in Fig. 8. FIG. 5 begins timing the intervals that give the main flow of the program. 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 RAM? Store it in the internal memory. In step 3, it is checked whether the main engine FO flowmeter pulse is input to the input boat 6, and if yes, the process branches to subroutine (2) for timing the FO flowmeter pulse interval. In step 4, the timer ■ is checked to determine whether it is time to make a slight speed change, and if it is y6s, the timer ■ is reset to start measuring the current ship speed, and the ship speed measurement number counter C is reset. In step 5, check the timer ■, determine whether it is time to measure the ship's speed, and then
If s, the process branches to subroutine (2) for ship speed measurement and post-measurement processing.

In step 6, the current dy/dx control 0N10FF is confirmed, and 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 calculated in subroutine (2) is held. Step 8
Now output Nout to the output boat and step 2
Return to

FIG. 6 shows the contents of subroutine I. RAM in step If? Read the elapsed time on the timer ■. RAM
? There are 10 memories T (1) to T (to) for storing the FO flow meter pulse interval T, and in step 12, the T read this time is entered in T (1), and T (2
) is T (1), T (3) is T (2), T (N
) stores T (N-1).

In step 13, the timer I is reset in preparation for timing the next FO flow meter pulse interval, and the process returns to the main flow.

FIG. 7 shows the contents of subroutine (2). The RAM 7 includes a counter C that counts the number of ship speed measurements and M memories v(1) to V(M
) is provided. In step 21, the A/D conversion value ■ of the ship speed signal 5 is read from the input boat 6. Step 2
Add 1 to counter C at 2. The ship speed V read in step 23 is stored in the memory V (C). Step 24
Determine whether the ship speed has been measured the specified number of times with y
If es, branch to 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 subroutine (2). RAM7 is memory X that stores the average ship speed and average fuel consumption measured last time.
(2) , Y (2) and X (1
), Y(1) is provided. In step 31, the average ship speed Vmean is determined from the ship speed values M specified times. In step 32, the average value T m of 10 FO flowmeter pulse intervals is
Find ean. In step 33, the proportionality constant T m
Fuel consumption per unit time 111FOc is calculated from ean. In step 34, the currently measured ship speed and fuel consumption per unit time are stored in X(1) and Y(1) of the previous measurements. 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, and if yes, the sign of the specified minute rotational speed change ΔN is set to negative in step 37, and if no, it is directly output to the output boat in step 38. Add ΔN to Nout. In step 39, the timer (2) is reset to determine the timing for applying the next minute speed change, and the process returns to the subroutine (2).

As explained above, this invention slightly changes the rotational speed of the main engine at certain intervals during a voyage, and changes Δx in ship speed and changes Δy in main engine fuel consumption per unit time due to changes in rotational speed. The main engine rotation speed is controlled so that the ratio Δy/Δx of the two matches the target value. - It has the effect of reducing fuel consumption per voyage.

[Brief explanation of drawings]

FIG. 1 shows a speed-fuel consumption curve for explaining the invention in detail, and FIG. 2 shows a model of the speed-fuel consumption curve assumed to compare the superiority of several main engine control methods.
FIG. 3 is a block diagram of a conventional main engine control system, FIG. 4 is a block diagram of a device used to implement the present invention, and FIG. 5 is a flowchart of a program for operating the CPU shown in FIG.
6 and 7 are flowcharts showing the contents of subroutines 1 and II of FIG. 5, respectively, and FIG. 8 is a flowchart showing the contents of subroutine (2) of FIG. 7.

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 due to the change in rotational speed, Δx, and the change in main engine fuel consumption per unit time, Δy, are measured, and the ratio of the two is calculated. Δy/Δx is compared with the target value, and 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 so that the difference between Δy/Δx and the target value disappears. A method for controlling a main engine of a ship, the method comprising: controlling the main engine of a ship;