JPH0310343Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of the invention This invention relates to an improvement of a supply air temperature regulating device in a diesel engine with an air cooler.

B. Prior Art Conventionally, in this type of engine, when the set value of the supply air temperature is satisfied in the high load range, the supply air temperature decreases as the load decreases, and especially in the low load range, the supply air temperature at the outlet of the supercharger ( In other words, the supply air temperature at the air cooler inlet) did not rise to the set value, and even if the supply of cooling water to the air cooler was stopped, the engine supply air temperature could not be expected to rise (see Figure 3). This causes problems such as poor combustion and abnormal wear of cylinder liners and piston rings. Therefore, it is desirable to increase the supply air temperature in the low load range. Especially when using low-quality oil fuel at low loads, it is necessary to set the temperature higher (60°C to 70°C) than the set temperature in the high load range (40°C to 50°C).

As a prior art, there is a device described in Japanese Utility Model Publication No. 58-13075. In this conventional device, seawater is passed downstream of the air in the air cooler. However, if seawater is bypassed during low load, the air temperature will decrease.
If the temperature rises above 50℃, salt will stick to the seawater cooling pipe in the air cooler. Therefore, the air temperature cannot be raised above 50°C. In addition, the temperature of the jacket cooling water passing through the upstream side of the air cooler also decreases.
However, it still has the drawback that it is unable to secure high-temperature cooling water of 75°C to 85°C at the jacket outlet, which is required for jacket-based cooling water.

C. Purpose of the invention The purpose of this invention is to provide an improved supply air temperature control device for diesel engines that can meet the demand for increased supply air temperature in the low load range and eliminate the drawbacks of the conventional devices as described above. It is something to do.

D. Structure of the invention The diesel engine supply air temperature control device of this invention is located downstream of the supercharger 2 and connects to the cooler system cooling water circuits 6 to 13 in which low-temperature cooling water circulates. 4, a second stage air cooler 5 located downstream of this first stage air cooler and connected to jacket system cooling water circuits 14 to 27 equipped with a fresh water cooler 16, and a jacket system cooling water circuit. It includes a switching valve 18 that operates depending on the load range.

E. Effect of the invention The supply air temperature control device for a diesel engine of this invention supplies jacket cooling water cooled by the fresh water cooler 16 to the second stage air cooler 5 during high load operation of the engine, thereby increasing the temperature to 40°C. By obtaining a supply air temperature of ~50°C, and on the other hand, entering low-load operation, the switching valve 18 is activated and the high-temperature jacket cooling water exiting the engine 1 is directly supplied to the second stage air cooler.
It works just fine when you get the supply air temperature between ℃ and 70℃.

F. Embodiments The features of this invention will become clearer from the following description of embodiments shown in the drawings.

Referring to the drawing, a diesel engine 1 is equipped with a supercharger 2, and air compressed by the supercharger 2 passes through an air supply pipe 3 and two-stage air coolers 4 and 5 disposed in the middle. It is supplied to the diesel engine 1.

The first stage air cooler 4 is located downstream of the supercharger 2 and is connected to the cooler system cooling water circuit. The cooler system cooling water circuit runs from the cooling water source to the cooling water pump 6, the first stage air cooler 4, the flow control valve 7, and the set value of 30°C.
It includes pipe lines 9 to 13 that connect to a cooling water pump 6 or a cooling water source via a temperature control valve 8.

A second stage air cooler 5 located downstream of the first stage air cooler 4 is connected to the jacket system cooling water circuit. The jacket system cooling water circuit is the cooling water pump 14.
From there, the cooling water passes through the cooling jacket of the diesel engine 1, passes through the temperature control valve 15 with a set value of 75°C, the fresh water cooler 16, the temperature control valve 17 with a set value of 38°C, the switching valve 18, and the second stage air cooler 5. Contains lines 19-27 leading to pump 14. Note that 28 and 29 are pipes that supply cooling seawater to the fresh water cooler 16.

The operation of this embodiment of the apparatus having such a configuration will be described as follows.

FIG. 1 shows the state of the device during high load operation of the engine. In this case, the cooling water that has passed through the cooling jacket of the engine 1 and is heated is passed through the fresh water cooler 16 by the temperature control valve 15 so that the cooling water temperature at the engine outlet is 75°C to 80°C. The water is divided into two parts: one that goes to the second stage air cooler 5, and the other that goes directly to the cooling water pump 14 through pipes 21 and 22. Since the engine 1 generates a large amount of heat under high load, most of the cooling water passes through the fresh water cooler 16 and is cooled to approximately 38° C. before proceeding to the second stage air cooler 5.

Cooler system cooling water flows from the cooling water pump 6 to the first stage air cooler 4, but the temperature control valve 8
The temperature is controlled between ℃ and 35℃.

Thus, in the high load range, the air from the supercharger 2 is transferred to the first and second stage air coolers 4, 5.
It is cooled to 40°C to 50°C. Note that the air temperature at the outlet of the air cooler can be adjusted by adjusting the amount of cooling water supplied to the first stage air cooler 4 using the flow control valve 7.

Next, referring to FIG. 2, which shows the state of the device during low-load operation of the engine, in this case, the switching valve 18 operates as shown in the figure to connect the pipe 21 to the pipe 25.
Then, the conduit 24 is also connected to the conduit 22. Note that the operation of the switching valve 18 is electrically controlled based on a signal related to a rack transmitter or a steering wheel position (none of which are shown). Therefore, the air coming out from engine 1 to the second stage air cooler 5
High temperature cooling water of 75℃~80℃ is supplied. Therefore, when the air from the supercharger 2 is lower than the above-mentioned temperature of the cooler system cooling water of 30°C to 35°C,
After being heated by the stage air cooler 4, it is further heated to 60°C to 70°C by the second stage air cooler 5.

Thus, in a low load range, even if the air temperature at the outlet of the supercharger 2 is low, high temperature air can be supplied to the engine 1.

G. Effects of the invention The diesel engine supply air temperature control device of this invention can automatically control the supply air temperature according to the load range so as to increase the supply air temperature when the engine is operating at low load.

The effect of this invention can be seen in Figures 3 (for conventional equipment) and 4, which show the relationship between load and supply air temperature.
It is clear from the figure (for the device of the present invention). In these figures, the symbols mean the following: a... Supply air temperature at the inlet of the first stage air cooler b... Supply air temperature at the second stage air cooler c... Room temperature d... Cooler system cooling water Cooling water temperature of the circuit e...Cooling water temperature of the jacket system cooling water circuit

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the device according to this invention, showing the state under high load.
Fig. 2 is a block diagram similar to Fig. 1 showing the state at low load, Fig. 3 is a graph showing the relationship between load and supply air temperature in the conventional device, and Fig. 4 is a graph showing the relationship between load and supply air temperature in the device according to this invention. It is a graph showing the relationship between supply air temperature. 1... Diesel engine, 2... Supercharger, 3...
Air supply pipe, 4... First stage air cooler, 5... Second stage air cooler, 6 to 13... Cooler system cooling water circuit,
14-27... Jacket system cooling water circuit, 18...
...Switching valve.

Claims (1)

[Scope of utility model registration request] A first-stage air cooler located downstream of the supercharger and connected to the cooler system cooling water circuit that circulates low-temperature cooling water, and a fresh water cooler located downstream of the first-stage air cooler. A second stage air cooler is connected to the jacket system cooling water circuit, and when the engine is operating at high load, high temperature cooling water from the engine is sent to the second stage air cooler via the fresh water cooler, while during low load operation A diesel engine supply air temperature control device that sometimes consists of a switching valve that sends high-temperature cooling water from the engine directly to the second stage air cooler.