JPS6046249B2 - Diesel engine supply air cooling system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in charge air cooling systems for diesel engines.

A conventional charge air cooling system for a marine diesel engine is shown in FIG.

The marine diesel engine 3 attempts to increase its efficiency by pressurizing the combustion air (which also serves as scavenging air) with the supercharger 5, but the density is low due to thermal expansion due to the heat generated during pressurization. , and the effect is canceled out. Therefore,
Generally, an air cooler is installed and the seawater is used for cooling.
As shown in the figure, by sending sea water from the sea peak 1 below the water line A of the ship to the air cooler 4 of the diesel engine 3 using the sea water pump 2, the air sent by the supercharger 5 is cooled and the engine is cooled. We use methods to increase efficiency. To prevent the air from becoming overcooled, the temperature is automatically controlled by recirculating a portion of the warm seawater using a three-way automatic temperature control valve 6. Note that 8 indicates the air outlet of the air cooler, and arrow B indicates the flow of air. However, in humid regions or when the weather is humid, a large amount of water droplets come out in the air cooler 4 due to the set temperature of the cooling seawater (usually 25°C), and when this enters the cylinder that forms the combustion chamber, the lubricated state It is believed that this causes abnormal wear of the cylinder liner.

Therefore, the temperature of the three-way automatic control valve 6 is currently detected at a point on the seawater passage from the seawater pump 2 to the air cooler 4, that is, at the temperature sensor 7, at approximately 25°C, but this is only the optimum value for the air temperature. It is the greatest common divisor assuming that
On the one hand, crew members want to keep the temperature as low as possible, but on the other hand, they are also very concerned about the possibility of water droplets forming in humid conditions, even though they have invested in an expensive three-way automatic temperature control valve 6. , it cannot be said that the diesel engine is operating at maximum efficiency.

An object of the present invention is to focus on the above-mentioned points, and to provide a supply air cooling device that can control the temperature of cooling water by detecting the humidity of air exiting an air cooler. is a temperature sensor that detects the temperature of the cooling water sent to the air cooler or the temperature of the air that comes out of the air cooler, a humidity detection sensor that detects the humidity of the air that comes out of the air cooler, and a humidity sensor that detects the humidity of the air that comes out of the air cooler. One feature is that it includes a cooling water flow control valve that adjusts the recirculation flow rate of cooling water in response to an output signal.

In this case, the crew can increase the efficiency of the engine by using cooled air above the dew point without worrying about abnormal wear of the Schilling liner due to humid overcooling. Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is an explanatory diagram showing an embodiment of the supply air cooling device according to the present invention.

In the figure, a three-way automatic temperature control valve is used to cool the air from a supercharger 5 by sending sea water from a sea chest 1 below the water line A of the ship to an air cooler 4 of a diesel engine 3 using a sea water pump 2. Humidity sensor 7 as control detector of 6
'' is provided at the outlet 8 of the air cooler.

In addition to the humidity sensor 7'', the temperature sensor 7 may be left as is conventional, or a temperature sensor r may be provided at the outlet 8 of the air cooler, and control is performed by a combination thereof.

The operation in the case of the above configuration will be described.

By using the humidity sensor 7″ as a control detector for the three-way automatic control valve 6, if the actual air humidity becomes higher than the set humidity, the return cooling water from the air cooler 4 is routed through the three-way automatic control valve 6. Increase the amount of recirculated seawater in the passage 9 that short-circuits the seawater pump 2 to the suction hole (the opposite operation is performed if the actual air humidity is low), and supplies the coolest air within the dew point to the combustion chamber (cylinder) of the engine. can be sent to.

If only the above is used, there is a risk that the air will become overcooled in cold weather. Therefore, depending on the route, etc., the conventional temperature sensor 7 may be left in place, or the temperature sensor 7'' may be added to the air outlet side of the air cooler to reduce humidity and temperature. (for example,
If the temperature sensor 7 becomes 20°C or less and the temperature sensor 7'' becomes 40°C or less, switch to temperature control).

In addition, over the past year or two, humidity sensors have become more compact and high-performance (
High accuracy and high responsiveness) have been realized.

The present invention as described above has the following effects.

Conventionally, the cooling water in the air cooler of a diesel engine was controlled by controlling the amount of circulating water by detecting the cooling water temperature.
By detecting the humidity of the air on the side to be cooled, the air can be cooled to near the dew point depending on the relative humidity.

This improves the efficiency of the engine and prevents troubles such as abnormal wear of the cylinder liner due to dew droplets. Note that the present invention can also be applied when the cooling water is not seawater but fresh water (recent ships are increasingly cooling with fresh water due to the adoption of central cooling systems).

Furthermore, although a marine diesel engine has been described, it is of course possible to employ a land diesel engine as well.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing a conventional charge air cooling device for a marine diesel engine, and FIG. 2 is an explanatory view showing an embodiment of the charge air cooling device for a marine diesel engine according to the present invention. 1...Sea CHEST, 2...Sea water pump, 3...Diesel engine, 4...Air cooler, 5...Supercharger, 6...Three-way automatic control valve, 7,7''...Temperature sensor, 7''...
・Humidity sensor, 8... Air cooler outlet.

Claims (1)

[Claims] 1 In the air supply system of a diesel engine, a temperature sensor that detects the temperature of the cooling water sent to the air cooler or the temperature of the air discharged from the air cooler, and a humidity sensor that detects the humidity of the air discharged from the air cooler. A charge air cooling device for a diesel engine, comprising a sensor and a cooling water flow rate control valve that adjusts the recirculation flow rate of cooling water in response to output signals from both of the sensors.