JPS61145314A - Cooling device in engine - Google Patents

Abstract

PURPOSE:To prevent a cylinder block from being corroded by sulfuric acid, by forming a cooling water jacket for a seawater cooled cylinder head and a cooling water jacket for a fresh water cooled cylinder block, separately from each other, and by providing a heat-exchanger in which fresh water is cooled with the use of seawater. CONSTITUTION:A cooling water jacket 17a for a seawater cooled cylinder head 17 and a cooling water jacket 19a for a fresh water cooled cylinder block 19 are formed separately from each other. Further, there is provided a heat- exchanger 34 in which seawater flowing into the cooling water jacket 17a for the cylinder head 17 cools fresh water flowing into the cooling water jacket 19a for the cylinder block 19. With this arrangement, the cylinder head having a high calorific value may be sufficiently cooled directly by seawater while the cylinder block 19 is prevented from being excessively cooled and from being corroded by sulfuric acid.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a cooling device for an engine used, for example, in an outboard motor.

(Prior Art) Generally, an outboard motor draws in seawater as cooling water, and the engine is directly cooled with the drawn seawater. For this reason, there is a tendency that the cylinder 10 part, which generates a relatively small amount of heat, becomes overcooled.

Incidentally, in recent years, f easel engine outboard motors using diesel engines have been developed. When the above-mentioned direct seawater cooling structure is applied to this diesel engine outboard motor, the following problems occur. In other words, the light oil used as diesel fuel contains sulfur, and when the sulfur is combusted, SO
3 occurs.

If a diesel engine, which is filled with SO3, is directly cooled with relatively low-temperature seawater, the cylinder liner, etc., will become extremely low temperature, condensing the SO3 and producing sulfuric acid.
However, a problem occurs in which FJ sulfuric acid corrosion occurs. This problem is particularly noticeable at low loads when the amount of heat generated from the diesel engine is small. When diesel engine outboard motors are used for work, they are often used at low loads, so cylinder liner wear due to sulfuric acid corrosion can occur. The problem is that it increases.

In addition, there is a prior art technology (Utility Model Publication No. 53-24077) that prevents overcooling of the engine by installing a valve in the seawater intake port for outboard motors that are directly cooled with seawater. If it is allowed to flow, there is a problem in that calcium and other components in the seawater precipitate and become scales that adhere to the inside of the engine.

Therefore, for engines used in, for example, outboard motors, there is a need for a cooling device that can sufficiently cool the cylinder head and prevent overcooling of the cylinder block.

Therefore, the applicant has developed a device in which fresh water is poured into the cooling water jacket of the engine, and the fresh water is indirectly cooled by seawater, and has already filed an application (filing date: November 16, 1980).

However, such prior art has a problem in that the heat exchanger is large and the external size of the engine is increased.

(Objective of the Invention) An object of the present invention is to provide an engine cooling device that can sufficiently cool a cylinder head, which generates a large amount of heat, by direct cooling of seawater, and can prevent overcooling and sulfuric acid corrosion of the cylinder block. It is said that

(Structure of the Invention) The present invention forms a cooling water jacket for a cylinder head that is cooled by seawater and a cooling water jacket for a cylinder block that is cooled by fresh water. The engine cooling device is characterized in that it includes a heat exchanger that cools the fresh water.

(Example) In FIG. 1 showing the case where the present invention is applied to a diesel engine and mounted on an outboard motor, 10 is a hull, and a diesel engine outboard 8114 is connected to the rearmost part of the hull 10 via a bracket 12. is installed. The diesel engine outboard 8114 has a structure in which a diesel engine 16 and a drive unit 18 are combined, the diesel engine 16 is covered with a cowling 20, and the drive unit 18 is provided with a propeller 22.

The diesel engine outboard motor 14 is rotatably attached to the bracket 12 via an arm 23 stacked on the bracket 12 around a shaft 24, and is used during so-called tilting when the propeller 22 is raised out of the water or when the drive unit 1
When the diesel engine 8 collides with a rock or other object, the entire diesel engine outboard 8114 can rotate around the shaft 24.

The diesel engine 16 is fixed with the crankshaft 15 arranged vertically, and the diesel engine 16
The cylinder head 17 and cylinder block 19 are arranged in parallel in the lateral direction. The cooling water jacket 17a of the cylinder head 17 is formed to allow cooling water to flow in the vertical direction, and the cooling water jacket 19a of the cylinder block 19 is similarly formed.

The seawater supplied to the cooling water jacket 17a is pumped by a seawater pump 28 in the drive unit 18, and after cooling is discharged into the water through a passage 30 in the drive unit 18.

An exhaust pipe 32 of the diesel engine 16 also opens into the passage 30.

The cooling system of the diesel engine 16 will be explained with reference to FIG. A heat exchanger 34 is fixed in close contact with the cylinder head 17 at a position facing the seawater inlet 17b. The heat exchanger 34 is a so-called multi-plate heat exchanger, in which fresh water, which is a medium to be cooled, is passed through the core 36a.
The structure is such that seawater from the seawater pump 28 flows around the seawater pump 68.

The seawater outlet 36b of the heat exchanger 34 is in direct communication with the seawater inlet 17b of the cylinder head 17 via the communication hole 37, and the seawater from the seawater pump 28 passes through the heat exchanger 34 and then flows into the seawater. The water flows into the cooling water jacket 17a from the water inlet 17b, and is discharged to the outside through the passage 35 from the seawater outlet 17c. A thermostat T1 is provided near the seawater outlet 17G of the cylinder head 17, and the thermostat T1 controls the temperature of the seawater flowing through the cooling water jacket 17a.

The outlet of the core 368 is connected to the fresh water inlet 19b of the cooling water jacket 19a.
The fresh water outlet 19C is connected to a fresh water tank 38 provided at the top of the cylinder block 19. A passage 42 connects the fresh water tank 38 and the cold water pump 40 for circulating fresh water.

The cooling water pump 40 and the core 36a are connected through a passage 44, and a thermostat T2 is interposed in the passage 44. Thermostat T2 and fresh water inlet 19
b are connected by a passage 46, and the thermostat ■
When thermostat T2 is open, fresh water from the cooling water pump 40 flows into the core 368, and when thermostat T2 is closed, fresh water is circulated from the passage 46 to the cooling water jacket 19a. In addition, thermostat T
The valve opening temperature of No. 2 is set higher than that of thermostat T1.

A structure in which the above-mentioned cooling system is provided in an actual diesel engine 16 for an outboard engine will be explained with reference to FIGS. 3 and 4.

In FIGS. 3 and 4, parts given the same reference numerals as in FIGS. 1 and 2 indicate the same or equivalent parts.

In FIG. 3 when the diesel engine 16 is viewed from above, 50 is a camshaft, and the camshaft 50 has a sprocket 5.
2 is fixed. A timing belt 54 is wound around the sprocket 52, and the timing belt 5
4 to rotate the cooling water pump 40. The cooling water pump 40 is integrally provided on the side surface of the cylinder block 19, and a pulley 58 is in pressure contact with the timing belt 54.

Cylinder head 1 on the camshaft 50 side from the cooling water pump 40
The heat exchanger 34 is provided in close contact with the side surface of 7. The heat exchanger 34 has a structure in which a core 36a is housed in a frame 60 and covered with a cover 64, and the cylinder head 17
A partition plate 66 is provided between the cooling water jacket 17a, which is open on the side surface of the cooling water jacket 17a, and the frame body 60. A communication hole 37 is formed in the partition plate 66, and the communication hole 37 connects the heat exchanger 34.
The cooling water jacket 17a is in direct communication with the cooling water jacket 17a.

The communication hole 37 is arranged at the upper part of the partition plate 66 as shown in FIG. A seawater inlet 68 is formed in the lower part of the partition plate 66, and the seawater pump 2 is connected from the seawater inlet 68 to the seawater inlet 68.
The seawater pumped by 8 is guided into the heat exchanger 34 and
6a and the seawater after heat exchange is passed through the communication hole 37.
The structure is such that the seawater flows from the seawater into the seawater inlet 17b of the cooling water jacket 17a. A thermostat 1 is provided at the outlet of the cooling water jacket 17a, and the seawater whose temperature is controlled by the thermostat T1 is discharged through a passage 35. The passage 35 is integrally formed within the wall thickness of the frame 60, and the passage 35 is connected to the passage 30 (FIG. 1).

Fresh water flows into the core 36a through a passage 44, and the fresh water indirectly cooled by low-temperature seawater in the heat exchanger 34 flows into the cooling water jacket 19a (FIG. 2) from the fresh water inlet 19b. be. The upstream end of the passage 44 is connected to a thermostat T2, and the thermostat T2 is arranged near the cooling water pump 40.

A fresh water tank 38 is integrally provided above the heat exchanger 34, and the fresh water tank 38 has a fresh water outlet 19C (a second
After cooling the cylinder block 19, fresh water flows in from the cylinder block 19 (Fig.
0 is designed to distribute fresh water. A removable filler cap 70 is provided at the top of the fresh water tank 38.

Next, the effect will be explained. The amount of heat generated during operation of the diesel engine 16 is greater in the cylinder head 17 than in one cylinder block, and the cylinder head 17 has a relatively high temperature. Furthermore, since the cylinder head 17 is formed with an intake boat, etc., it is desirable to cool the cylinder head 17 to a temperature lower than that of the cylinder block 19 in order to improve intake efficiency. On the other hand, if the cylinder block 19 is overcooled, sulfuric acid corrosion is likely to occur, so it is desirable to maintain the cylinder block 19 at a higher temperature than the cylinder head 17.

Therefore, low-temperature seawater is passed from a seawater tank 128 to the cooling water jacket 17a that cools the cylinder head 17.
The cylinder head 17 is maintained at a relatively low temperature while controlling the temperature with a thermostat T1. Fresh water stored in a fresh water tank 38 is circulated in the cooling water jacket 19a that cools the cylinder block 19 by a cooling water pump 40, and the temperature is controlled to be relatively low by the thermostat T2. There is no risk that sulfuric acid corrosion will occur on the liner or that calcium in seawater will adhere as scale. Cooling water jacket 19a
When the temperature of the fresh water in the cooling water jackets 17a1. : Cooled by seawater before entering. Therefore, it is sufficient for the heat exchanger 34 to have a capacity sufficient to exchange heat with the fresh water that cools the cylinder block 19.
Since heat exchange is performed with low-temperature seawater before flowing into 7a, it is further miniaturized.

The heat exchanger 34 has a partition plate 66 on the side of the cylinder head 17.
Since the seawater outlet 36 of the heat exchanger 34 is partitioned and closely connected, the seawater outlet 36 of the heat exchanger 34 passes through the communication hole 37 formed in the partition plate 66.
b (Fig. 2) and the seawater inlet 1 of the cooling water jacket 17a.
7b is directly communicated, and connects the seawater outlet 36b and the seawater inlet 17b without providing any special piping or the like. Therefore, even if the diesel engine 16 is provided with the heat exchanger 34, the external size of the diesel engine 16 will not become unnecessarily large, and the entire diesel engine 16 can be made compact.

The fresh water tank 38 is integrally formed in the frame 60 of the heat exchanger 34, and the passage 35 is formed within the wall thickness of the frame 60, so the heat exchanger 34 is further miniaturized. .

(Effects of the Invention) As explained above, the engine cooling system according to the present invention separates the cooling water jacket 17a of the cylinder head 17 cooled by seawater from the cooling water jacket 19a of the cylinder block 19 cooled by fresh water. Since the heat exchanger 34 is provided to cool the fresh water with the seawater flowing into the cooling water jacket 17a of the cylinder head 17, the following effects can be achieved.

That is, the cylinder head 17, which is preferably cooled to a low temperature, is cooled to a relatively low temperature with seawater, and the cylinder block 19, which is preferably maintained at a temperature higher than that of the cylinder head 17, is cooled with fresh water, which flows through the cooling water jacket 19a. Fresh water can be indirectly cooled by the heat exchanger 34, and the capacity of the heat exchanger 34 can be reduced by the cylinder block 1.
It is possible to reduce the size to such an extent that heat exchange is possible for the apocalypse generated from 9. Therefore, it is most suitable for diesel engine outboard engines, which are prone to problems such as sulfuric acid corrosion.

Further, the heat exchanger 34 is arranged closely near the seawater inlet of the cooling water jacket of the cylinder head 17, and the seawater outlet 36b of the heat exchanger 34 and the seawater inlet 17b of the cooling water jacket 17a of the cylinder head 17 are directly connected. When formed in this manner, the following effects can be achieved.

That is, the heat exchanger 34 can be placed in close contact with the side surface of the cylinder head 17 while being partitioned by the partition plate 66, and even when the heat exchanger 34 is installed in the diesel engine 16, the external size of the diesel engine 16 can be reduced. can do.

Furthermore, since the communication hole 37 is formed in the partition plate 66,
Seawater outlet 36b of heat exchanger 34 and cooling water jacket 1
Seawater inlet 17b of seawater inlet 7a can be directly communicated without using special piping or the like, and the structure can be simplified and the diesel engine 16 can be further downsized.

(Another Embodiment) (1) The present invention is not limited to the case where it is applied to a diesel engine outboard motor as described above.
The present invention can be applied to other engines such as gasoline engines in which the nine cooling water jackets 19a are formed separately. However, when applied to a diesel engine outboard motor, the above-mentioned problems such as fi+acid corrosion can be solved and it is most suitable.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the structure of a diesel engine outboard motor to which the Kinoe type is applied, Figure 2 is a diagram of the structure showing the cooling system, Figure 3 is a partially cutaway side view of the diesel engine, and Figure 4 is a diagram of the diesel engine. FIG. 3 is a partially cutaway side view. 16...Diesel engine, 17...Cylinder head, 17a.
...Cooling water jacket, 19...Cylinder block, 19a...Cooling water jacket, 34...Heat exchanger, 36a...Core, 37...Communication hole, 38...
Fresh water tank, 40...Cooling water pump, T1, T2...
・Thermostat-1-EFY, 1

Claims (2)

[Claims] (1) The cooling water jacket of the cylinder head, which is cooled by seawater, and the cooling water jacket of the cylinder block, which is cooled by fresh water, are formed by separating them, and the seawater flowing into the cooling water jacket of the cylinder head cools the fresh water. An engine cooling device characterized by being equipped with an exchanger. (2) The heat exchanger is arranged closely near the seawater inlet of the cooling water jacket of the cylinder head, and the seawater outlet of the heat exchanger is directly connected to the seawater inlet of the cooling water jacket of the cylinder head. An engine cooling device according to claim 1.