JPH0436250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the speed of a main cooling seawater pump for a marine diesel engine.

(Prior Art) In general, a marine diesel engine as the main engine of a ship is provided with a main cooling seawater pump 101, as shown in FIG. Oil cooler 103, jacket fresh water cooler 106 that cools fresh water for cooling the main engine jacket, piston fresh water cooler 100 that cools fresh water for cooling main engine pistons, water generator cooler 105, and other coolers 107 for cooling. of seawater.

Then, the outlet side fresh water temperature detection signal T _j S of the jacket fresh water cooler 106 and the outlet side fresh water temperature detection signal T _p S of the piston fresh water cooler 100 are input to the control device 111 that controls the rotation speed of the seawater pump 101 . , the rotation speed of the seawater pump 101 was controlled based on these detection signals T _j S and T _p S. That is, the rotation speed of the seawater pump 101 is controlled by performing feedback control on the rotation speed of the seawater pump 101 based on the fresh water temperature detection signals T _j S and T _p S. Note that the rotational speed of the seawater pump drive motor 101A is controlled by frequency conversion using an inverter.

Furthermore, the seawater flow rate to the air cooler 104 is controlled by controlling the temperature control valve 130 using the scavenging air temperature detection signal TaS on the outlet side of the air cooler 104, and the cooling seawater discharge pipe is controlled using the seawater temperature detection signal _TbS. By controlling the temperature control valve 108 of the seawater pump 101, the temperature of the seawater flowing into the seawater pump 101 is increased to prevent the seawater flow rate to the cooling system from decreasing too much by increasing the flow rate back to the upstream side of the seawater pump 101 when the seawater temperature is low. is being adjusted.

(Problems to be Solved by the Invention) In the above cooling system, feedback control is performed based on the two fresh water temperature detection signals T _j S and T _p S, and the temperature control valve is controlled based on the scavenging air temperature detection signal T _a S. 130, the configuration of the control device 111 becomes very complicated.

If the scavenging air temperature detection signal TaS is also fed back to the control device 111, control will become uncontrollable.
0, but in this case, when the temperature control valve 130 is operated to control the scavenging air temperature, the flow rate to each parallel branch system changes, so the flow rate to each branch system changes. Flow balance is impaired.

In particular, the fresh water generator is independent from the main engine, and the required seawater flow rate has no comparative relationship with the piston cooling fresh water temperature and the jacket cooling fresh water temperature, so the feedback control using the detection signals T _j S and T _p S is performed with sufficient margin. A certain setting must be used.

The cooling system shown in Figure 3 above is applied to a specific type of main engine, but in other types of main engines, the lubricating oil cooler 103 is connected in series to the air cooler 104, etc. It uses a significantly different cooling system.

When trying to control the rotation speed of the seawater pump 101 based on the fresh water temperature detection signals T _j S and T _p S by applying a control system similar to the above in this type of cooling system, the lubricating oil temperature cannot be adjusted to an appropriate temperature. There are problems such as unsustainability.

(Means for Solving the Problems) A speed control method of a main cooling seawater pump for a marine diesel engine according to the present invention provides a variable speed control method for supplying cooling seawater to a plurality of coolers attached to a marine diesel engine. In a speed control method for controlling the speed of a main cooling seawater pump, a cooler is interposed in each of a plurality of branch passages branching from a seawater introduction passage in which the seawater pump is interposed, and the flow rate of the plurality of branch passages is balanced. is properly set in advance, and the control means of the seawater pump is controlled to have a predetermined functional relationship between the load of the diesel engine and the rotational speed of the seawater pump, so that the load of the diesel engine changes from a full load state to a predetermined partial load state. A predetermined functional relationship such that the required seawater flow rate of the plurality of branch passages decreases at the same rate of decrease as the minimum rate of decrease when the seawater flow rate decreases, and a correction function that corrects this functional relationship according to the seawater temperature are prepared in advance. The target rotation speed of the seawater pump is determined by the control means from the predetermined functional relationship using the load detection signal of the diesel engine, and the target rotation speed is determined by the correction function using the seawater temperature detection signal. The rotational speed of the seawater pump is controlled by the control means so that the rotational speed of the seawater pump becomes the corrected target rotational speed.

(Function) In the speed control method of a main cooling seawater pump for a marine diesel engine according to the present invention, a cooler is interposed in each of a plurality of branch passages branching from a seawater introduction passage in which the seawater pump is interposed. The flow balance of these multiple branch passages is set appropriately in advance, and the control means of the seawater pump has a predetermined functional relationship between the load of the diesel engine and the rotation speed of the seawater pump, and the load of the diesel engine is set at full load. A predetermined functional relationship such that the required seawater flow rate of a plurality of branch passages decreases at the same rate of decrease as the minimum rate of decrease when decreasing from to a predetermined partial load state, and this functional relationship according to seawater temperature A correction function to be corrected is set in advance.

When the diesel engine is operating, the control means uses the load detection signal to determine the target rotation speed of the seawater pump from the predetermined functional relationship;
The target rotational speed is corrected using the correction function using the seawater temperature detection signal. Then, the seawater pump is controlled by the control means so that the corrected target rotation speed is achieved.

As mentioned above, since the flow balance of multiple branch passages is properly set in advance and the above-mentioned functional relationship is set with the above-mentioned characteristics, all the branches are Seawater greater than the required seawater flow rate is reliably supplied to the passage.

(Effects of the Invention) According to the speed control method of a main cooling seawater pump for a marine diesel engine according to the present invention, the flow balance of a plurality of branch passages is appropriately set in advance, By simply setting a predetermined functional relationship between the load and the rotational speed of the seawater pump and a correction function for this functional relationship according to the seawater temperature, all It is possible to reliably supply cooling seawater in excess of the required seawater flow rate to the branch passage, and to control the rotation speed of the seawater pump with a very simple control system that uses the diesel engine load detection signal and seawater temperature detection signal. I can do it.

In this seawater pump speed control method,
It controls the total flow rate of cooling seawater without changing the flow balance to each branch passage to which each cooler in the cooling system is connected, so it can be easily applied to various cooling systems attached to diesel engines. I can do it.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

First, a cooling system and its control system to which the speed control method of a main cooling seawater pump for a marine diesel engine according to the present invention is applied will be explained with reference to FIG.

A main cooling seawater pump 1 (hereinafter referred to as seawater pump) that supplies cooling seawater to various coolers attached to a marine diesel engine (hereinafter referred to as main engine) for driving a marine propulsion unit is connected to a seawater introduction passage 2. The seawater introduction passage 2 branches into a first branch passage 2a, a second branch passage 2b, and a third branch passage 2c on the downstream side of the seawater pump 1.
These join the seawater discharge channel 2A at a confluence point G.

A lubricating oil cooler 3 and an air cooler 4 for cooling scavenging air to the main engine are interposed in the first branch passage 2a in order from the upstream side, and a water generation device in the second branch passage 2b in order from the upstream side. A cooler 5 and a jacket fresh water cooler 6 are interposed, and a plurality of other coolers 7 are interposed in the third branch passage 2c.

A temperature control valve 8 is interposed in the seawater discharge path 2A downstream of the confluence point G, and a return passage 9 branched from the temperature control valve 8 is connected to the seawater introduction path 2 upstream of the seawater pump 1. , the temperature control valve 8 is controlled by the seawater temperature detection signal from the seawater temperature sensor 10.
In this way, if the seawater temperature is, for example, 16℃ or less,
By circulating warm seawater back to the suction side of the seawater pump 1 through the reflux passage 9, it is possible to prevent the flow rate of seawater flowing to each of the coolers 3 to 7 from decreasing too much due to a drop in the temperature of the cooling seawater. .

A control device 11 that controls the rotation speed of a pump drive motor 1A that drives the seawater pump 1 is provided, and a main engine load detector 1 that detects the load of the main engine.
2 and a seawater temperature sensor 13 that detects the seawater temperature in the seawater introduction passage 2 on the downstream side of the seawater pump 1, the load detection signal L from the main engine load detector 12 and the seawater temperature detection signal from the seawater temperature sensor 13 TsS
is output to the control device 11. The main engine load detector 12 detects the main engine rotation speed, main engine rotation speed setting governor input, or scavenging air pressure.
Furthermore, a fresh water temperature detection signal T _j S from a fresh water temperature sensor 14 that detects the fresh water temperature on the outlet side of the jacket fresh water cooler 6 is also output to the control device 11 .
Reference numerals 15 and 16 are temperature control valves, 17 is a control valve that adjusts the flow rate of the bypass path 18 of the air cooler 4 for initial setting, and 19 is a flow rate of the bypass path 20 of the water generator cooler 5. This is a control valve that adjusts the initial settings.

The first to third branch passages 2a, 2b, and 2c are set to have an appropriate flow balance.

The control device 11 includes an input port, a microcomputer, and a drive circuit, and the microcomputer includes a CPU (central processing unit), a ROM (read-only memory), and a RAM (random access memory). In the ROM, a predetermined functional relationship between the main engine load and the seawater pump rotation speed as shown, for example, by curve A in FIG.
A correction function for correcting the above-mentioned predetermined function according to seawater temperature is input and stored in the ROM in advance.

Furthermore, the ROM is programmed to calculate the target rotation speed from the predetermined functional relationship based on the main engine load detection signal L, correct the target rotation speed using a correction function based on the seawater temperature detection signal TsS, and obtain a corrected target rotation speed. A control program is stored in advance that calculates and outputs a control signal to a drive circuit (this drive circuit also includes an inverter) to control the rotation speed of the seawater pump 1 to the corrected target number.

The above-mentioned control program also outputs a control signal from the CPU to the drive circuit to control the rotation speed of the seawater pump 1 to increase to a predetermined rotation speed when the fresh water temperature on the outlet side of the jacket fresh water cooler 6 rises abnormally. Pre-stored in ROM.

Next, a seawater pump speed control method according to this embodiment will be explained.

First, the predetermined functional relationship (curve A in FIG. 2) between the main engine load and the seawater pump rotation speed is set as follows.

In the area of main engine load 80 to 100%, main engine load is 100%.
The required seawater flow rate of each of the first to third branch passages 2a, 2b, and 2c decreases at a specific rate of decrease as the flow rate decreases from 1 to 80%. Set the total seawater flow rate to decrease at the same rate of decrease.

For example, if the rate of decrease in the first branch passage 2a is the slowest, if the total seawater flow rate is set as above, the required seawater will flow to the first branch passage 2a within the main engine load range of 80 to 100%. A sufficient flow rate of seawater is supplied to the second and third branch passages 2b and 2c according to a predetermined flow rate balance.

On the other hand, in a region where the main engine load is less than 80%, the main engine load is adjusted so that an abnormal decrease in seawater flow rate does not occur in any of the branch passages 2a, 2b, and 2c when the seawater temperature is the lowest (for example, 16 degrees Celsius or lower). A predetermined functional relationship between and the seawater pump rotation speed is set.

In other words, if the flow rate of seawater to each of the coolers 3 to 7 is abnormally reduced, the normal functions of each of the coolers 3 to 7 will not be obtained, and the insides of the coolers 3 to 7 will become easily contaminated. be.

The predetermined functional relationship between the main engine load and the seawater pump rotation speed set as described above is as shown by curve A with a seawater temperature of 32° C. as a reference.

During operation of the main engine, the target rotation speed of the seawater pump 1 is calculated from the functional relationship corresponding to the curve A using the main engine load detection signal L in the control device 11.

Next, in the control device 11, the seawater temperature detection signal is
Using TsS, a corrected target rotational speed is calculated using a correction function of, for example, corrected target rotational speed=target rotational speed−constant×(32−TsA) (where TsA is the detected seawater temperature value (° C.)). In the example of FIG. 2, the above constant is 15 to 20.

The corrected target rotational speed corrected by the above correction function is as shown by curve B when the detected seawater temperature value is 24°C, and by curve C when the detected seawater temperature value is 16°C. However, the above correction function is based on the seawater temperature detection value 116
It is valid in the range from ℃ to 32℃, and curve C gives the lower limit of the rotation speed of the seawater pump, and the detected seawater temperature value is 35℃.
When the temperature is above ℃, change the rotation speed ratio of seawater pump 1.
100% (1200 rpm in the example in Figure 2) (see curve D)
shall be. In addition, the range of 32℃＜TsA＜35℃ is curve C.
Corrected by interpolation between and curve D.

The above correction function is merely an example, and the correction function may be set in the ROM using memory map data.

Next, in the control device 11, after calculating the corrected target rotation speed, the CPU outputs a control signal for controlling the pump drive motor so that the rotation speed of the seawater pump 1 becomes the corrected target rotation speed. to control the rotation speed of the seawater pump 1.

Note that the control device 11 in the above embodiment includes a function setting device for setting a predetermined functional relationship between the main engine load and the rotation speed of the seawater pump 1, and an operational circuit and a drive circuit including an operational amplifier and the like that performs correction according to the seawater temperature. It can also be configured with an analog circuit consisting of, etc.

Further, in the above embodiment, the first to third branch passages 2
A, 2b, 2c are controlled by a simple control system without destroying the flow balance, but a flow rate control valve is interposed in each upstream portion of the first to third branch passages 2a, 2b, 2c. If these are controlled by the control device 11, the flow balance can also be adjusted and more precisely controlled. In this case, the predetermined functional relationship between the main engine load and the rotation speed of the seawater pump 1 is such that each branch passage 2a, 2 decreases as the main engine load decreases.
It can be set based on the required minimum seawater flow rate which is the sum of the required seawater flow rates of b and 2c.

In addition, since the main engine load is proportional to the main engine rotation speed, the main engine rotation speed may be used instead of the main engine load.

According to the seawater pump speed control method according to the above embodiment, the rotation speed of the seawater pump can be controlled properly and without waste according to the seawater temperature using a simple control system, so that the electric power for driving the seawater pump can be significantly reduced. The method of the present invention can be applied regardless of the type of cooling system of the main engine, and the control system is simple, so the rotation speed of the seawater pump can be stabilized against fluctuations in the main engine load. Effects such as the ability to omit a temperature control valve for scavenging air temperature control, a scavenging air temperature detector, etc. can be obtained.

[Brief explanation of drawings]

Of the drawings, Figures 1 and 2 are related to an embodiment of the present invention. Figure 1 is a diagram showing a cooling system such as a cooler attached to the main engine and a seawater pump rotation speed control system, and Figure 2 is a diagram showing a seawater pump rotation speed control system. A diagram showing the relationship between the main engine load, the seawater pump, and the seawater temperature detection value, FIG. 3 is a diagram corresponding to FIG. 1 according to the prior art. 1... Main cooling seawater pump, 2a to 2c... 1st
~Third branch passageway, 3... Lubricating oil cooler, 4... Air cooler, 5... Water generator cooler, 6... Jacket fresh water cooler, 7... Other coolers, 11...
Control device, 12...main engine load detector, 13...sea water temperature sensor.

Claims (1)

[Scope of Claims] 1. In a speed control method for controlling the speed of a variable speed main cooling seawater pump that supplies cooling seawater to a plurality of coolers attached to a marine diesel engine, By installing a cooler in each of the multiple branch passages branching from the introduction passage,
The flow balance of these plurality of branch passages is appropriately set in advance, and the load of the diesel engine is set to the full load in a predetermined functional relationship between the load of the diesel engine and the rotational speed of the seawater pump to the control means of the seawater pump. A predetermined functional relationship such that the required seawater flow rate of a plurality of branch passages decreases at the same rate of decrease as the minimum rate of decrease when decreasing from a predetermined partial load condition to a predetermined partial load condition, and this functional relationship is applied to the seawater temperature. A correction function to be corrected accordingly is set in advance, and the control means calculates the target rotation speed of the seawater pump from the predetermined functional relationship using the load detection signal of the diesel engine, and calculates the target rotation speed of the seawater pump using the seawater temperature detection signal. A main cooling seawater pump for a marine diesel engine, characterized in that the target rotational speed is temperature-corrected by a correction function, and the rotational speed of the seawater pump is controlled by the control means so as to achieve the corrected target rotational speed. Speed control method.