JPH0231769B2 - - Google Patents

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, outboard motors draw in seawater as cooling water.
The engine is directly cooled by inhaled seawater. For this reason, there is a tendency for the cylinder block portion, which generates a relatively small amount of heat, to become overcooled.

Incidentally, in recent years, diesel 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. That is, diesel fuel contains sulfur, and when the sulfur is burned, sulfur dioxide gas is generated. If a diesel engine, which is filled with sulfur dioxide gas, is directly cooled with relatively low-temperature seawater, the cylinder liner, etc., will become extremely low temperature, causing the sulfur dioxide gas to condense and produce sulfuric acid, causing so-called sulfuric acid corrosion. occurs. This problem is especially 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 the cylinder liner wear increases due to sulfuric acid corrosion. There is a problem with doing so.

It is also well known that keeping the cylinder head temperature low increases volumetric efficiency due to the low intake air temperature, and keeping the cylinder block at an appropriate temperature reduces mechanical loss, resulting in a high output engine with low fuel consumption. While cooling the head sufficiently,
There is a need for a cooling device that prevents overcooling of the cylinder block.

(Objective of the Invention) An object of the present invention is to provide an engine cooling system capable of sufficiently cooling a cylinder head, which generates a large amount of heat, and preventing overcooling of the cylinder block.

(Structure of the Invention) The present invention is an engine in which the crankshaft is arranged vertically and the cylinder head and cylinder block are arranged horizontally in parallel, and the cooling water jacket of the cylinder head and the cooling water jacket of the cylinder block are separated. A seawater directly cooled marine engine is equipped with a thermostat that individually controls the cooling water temperature of each cooling water jacket, and seawater after cooling the cylinder head is passed through the cooling water jacket of the cylinder block. It is a cooling device.

(Example) In Fig. 1 showing the case where a diesel engine is mounted on an outboard motor, 10 is a hull, and the hull 1
A diesel engine outboard motor 14 is attached to the rearmost part of the motor vehicle 0 via a bracket 12. The diesel engine outboard motor 14 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 has a propeller 22.
is provided.

Diesel engine outboard motor 14 is attached to bracket 1
Bracket 1 via arm 23 superimposed on 2
When the propeller 22 is lifted out of the water during a so-called tilt, or when the drive unit 18 collides with an obstacle such as a rock, the propeller 22 rotates around the shaft 24 of the diesel engine ship. The entire outer machine 14 is rotatable.

The diesel engine 16 is fixed with the crankshaft 15 arranged vertically, and the cylinder head 17 and cylinder block 19 of the diesel engine 16 are arranged horizontally in parallel. The cooling water jacket 17a of the cylinder head 17 is formed to allow cooling water to flow in the vertical direction.
9a is similarly formed.

The seawater supplied to the cooling water jackets 17a and 19a is supplied to the seawater pump 28 in the drive unit 18.
The structure is such that the liquid is pumped through the water and, after cooling, is discharged into the water through a passage 30 within the drive unit 18. An exhaust pipe 32 of the diesel engine 16 also opens into the passage 30.

A first embodiment of the cooling system for the diesel engine 16 will be described with reference to FIG. In this embodiment, the temperature of the seawater flowing through the cooling water jacket 17a is controlled to t2, and the temperature of the seawater flowing through the cooling water jacket 19a is controlled to t3 (t2<t3).

The seawater pumped up by the seawater pump 28 has a low temperature, t0 (t2>t0). A cooling water inlet 17b is formed in the upper part of the cylinder head 17,
At the bottom of the cylinder head 17 is a cooling water outlet 17c.
The seawater pump 28 and the cooling water inlet 17b are connected through a passage 40. A thermostat T1 is provided near the cooling water outlet 17c, and the valve opening temperature of the thermostat T1 is set to t2. The thermostat T1 and the cooling water inlet 19b of the cooling water jacket 19a are connected through a passage 42, and the cooling water inlet 19b is provided at the lower part of the cylinder block 19. An auxiliary cooling water outlet 19c and a main cooling water outlet 19d are provided at the upper end of the cooling water jacket 19a, and a thermostat T2 is arranged near the auxiliary cooling water outlet 19c. Note that a thermostat T1 may be provided near the main cooling water outlet 19d.

Therefore, the cooling water jacket cylinder head 1
7a from the cooling water inlet 17b to the cooling water outlet 17c.
The cooling water jacket 19a has a structure in which seawater flows downward from the cooling water inlet 19b to the main cooling water outlet 19d.

The valve opening temperature of thermostat T2 is t3, one end of passage 44 is connected to thermostat T2, and the other end of passage 44 is connected to passage 30 (FIG. 1).

Thermostat T1 is installed near the main cooling water outlet 19d.
(valve opening temperature t2), one end of the passage 46 is connected to the thermostat T1, and the passage 46 is connected to the thermostat T1.
The other end is connected to the middle of the passage 44. A switching valve 48 is interposed in the middle of the passage 46, and when the cylinder block 19 generates a large amount of heat under high load, the switching valve 48 is opened to divert the cooling water jacket 1.
Seawater at a temperature of t2 is allowed to flow through the cooling water jacket 19a, and when the cylinder block 19 is under low load, such as when idling, when the amount of heat generated is small, the switching valve 48 is closed and seawater at a temperature of t3 is allowed to flow through the cooling water jacket 19a. There is. The switching valve 48 is opened and closed manually or automatically.

Note that normally, when the thermostat T1 is provided at the cooling water inlet 17b, the thermostat T1 is not provided at the main cooling water outlet 19d, and the cooling water inlet 17b,
Alternatively, a thermostat T1 is provided at either one of the main cooling water outlets 19d.

The passage 44 and the passage 40 are communicated by a bypass passage 50, and the end of the bypass passage 50 is connected to a water test hole (not shown) for confirming normal operation of the cooling water pump.

The lower end of the passage 52 is connected to the upper part of the cooling water jacket 17a, and the upper end of the passage 52 is connected to the passage 4.
It is connected in the middle of 4. A float valve 54 for air bleeding is interposed in the middle of the passage 52, and the cooling water jacket 17a is supplied from the float valve 54.
It is designed to expel air trapped inside. Further, the upper end of a drain passage 58 having a throttle 56 is connected to the lower part of the cooling water jacket 17a, and the lower end of the drain passage 58 is connected to the middle of the passage 42.

The lower end of a passage 62 having a float valve 60 for air bleeding is also connected to the upper part of the cooling water jacket 19a, and the upper end of the passage 62 is connected to the middle of the passage 44. A passage 66 having a check valve 64 is also connected between the passage 42 and the bypass passage 50. A throttle 68 is interposed near the left side of the connection point p between the passage 66 and the bypass passage 50 in the drawing, and the switching valve 48 is in the closed state and the thermostat T is in the closed state.
Even when thermostat T2 is in the open state and thermostat T2 is in the closed state, the check valve 64 does not open due to the pressure of seawater from the cooling water jacket 17a, and the cooling water jacket 17
The seawater a remains in the cooling water jacket 17a until the temperature reaches t3 at which the thermostat T2 opens.

Furthermore, when the diesel engine 16 is stopped, it is common for outboard motors to discharge the seawater in the cooling water jackets 17a and 19a, but when the diesel engine 16 is stopped, the weight of the seawater causes the check valve 64 to be discharged. The valve is opened and discharged into the passage 30.

Next, the effect will be explained. First, when the throttle 68 is provided on the left side, the temperature of the cooling water jacket 19a is controlled at t3 when the switching valve 48 is closed, such as during idling. In other words, seawater pump 2 at temperature t0
The seawater flowing into the cooling water inlet 17b from the cooling water jacket 17a mixes with the relatively high temperature seawater that has gathered at the top due to the target phenomenon in the cooling water jacket 17a, and reaches a temperature of t1. The seawater that has flowed into the cooling water jacket 17a is
The temperature rises with a relatively small temperature gradient from t1 to t2, and at the temperature of t2, the thermostat T1 of the cylinder head 17 opens, but the check valve 64 remains closed due to seawater pressure, and the cylinder block 1
9 thermostat T2 also remains closed,
Seawater remains stagnant. As it cools down, the temperature of the jacket 19a rises, reaching the temperature t3, which opens the thermostat T2, and the cooling water jacket 17a opens.
The seawater from a cools and flows from the inlet 19b to the auxiliary cooling water outlet 19c, and from the passage 44 to the passage 3.
Ejected to 0.

Therefore, during idle time, that is, when the switching valve 48 is closed, the seawater temperature is controlled to a relatively high temperature t3 by the thermostat T2, and there is no fear that the aforementioned sulfuric acid corrosion will occur in the cylinder liner of the cylinder block 19.

On the other hand, when the load is high during full-power cruising, the switching valve 48 is opened, and the seawater in the cooling water jacket 19a flows from the cooling water inlet 19b toward the main cooling water outlet 19d, and is discharged from the passage 46 to the passage 30.

Therefore, when the engine is idle, that is, when the switching valve 48 is closed, the seawater temperature is controlled to a relatively high temperature t3 by the thermostat T2, and there is no possibility that the aforementioned sulfuric acid corrosion will occur on the cylinder liner of the cylinder block 19.

On the other hand, when sailing at full power, the switching valve 48 is opened for cooling, and the seawater in the jacket 19a flows from the cooling water inlet 19b toward the main cooling water outlet 19d, and flows through the passage 46.
and is discharged into the passageway 30.

Therefore, when the switching valve 48 is open, the temperature is controlled by the thermostat T1. Since the amount of heat generated from the cylinder block 19 increases during this high load, there is no risk of sulfuric acid corrosion occurring even if the temperature is controlled at a relatively low temperature t2.

On the other hand, the cylinder head 17a is cooled to a low temperature t2, and the intake port (not shown) of the cylinder head 17 is cooled to a low temperature t2.
etc. to a low temperature to improve the filling efficiency of intake air,
Also, between the intake and exhaust valves of the cylinder head 17 (not shown)
The heat load is also reduced.

Further, as another embodiment, a case will be described in which the diaphragm 68 is arranged on the right side of the connection point p as shown by the broken line in the figure. When the switching valve 48 is closed, the thermostat T1 is opened and the thermostat T2 is closed.
When the valve is closed, the seawater from the cooling water jacket 17a is passed through the passage 42, the passage 66, and the bypass passage 5.
0, the passage 44 is sequentially passed through and discharged to the passage 30. That is, cooling water jacket 1
The temperature of the cooling water jacket 7a is controlled by a thermostat T1, and the temperature of the cooling water jacket 19a is controlled by a thermostat T2.

On the other hand, when the switching valve 48 is closed, such as during idling, the temperature of the cooling water jacket 17a is controlled at t2, and the temperature of the cooling water jacket 19a is controlled at t3. That is, the seawater flowing into the cooling water inlet 17b from the seawater pump 28 at a temperature of t0 mixes with the relatively high temperature seawater that has gathered at the top due to the convection phenomenon within the cooling water jacket 17a, and reaches a temperature of t1. The temperature of the seawater that has flowed into the cooling water jacket 17a increases with a relatively small temperature gradient from t1 to t2, and at the temperature of t2, the temperature of the seawater increases.
When the thermostat T1 of No. 7 opens, the pressure of seawater opens the check valve 64, and the passages 42, 66,
It is discharged into the passageway 30 through the bypass passageway 50.

On the other hand, connect the thermostat T1 to the main cooling water outlet 19d.
If the thermostat T1 near the cooling water outlet 17c is removed, the passage 42 only needs to connect the adjacent cooling water outlet 17c and the cooling water inlet 19b. 17 and cylinder block 19 by casting.

Eventually, the temperature of the seawater in the cooling water jacket 19a increases.
When the temperature rises from t2 to t3, the thermostat T2 opens, and the seawater from the cooling water jacket 17a flows from the cooling water inlet 19b toward the auxiliary cooling water outlet 19c, and is discharged from the passage 44 to the passage 30.

Therefore, the temperature of the cylinder block 19 is controlled at a relatively high temperature t3, and there is no fear that the cylinder liner of the cylinder block 19 will suffer from the aforementioned sulfuric acid corrosion.

Moreover, the seawater flowing into the cooling water jacket 19a when the thermostat T2 opens is t1 in the cooling water jacket 17a of the cylinder head 17.
Since the temperature rises with a relatively small temperature gradient from
The temperature of the piston ring 9, especially the temperature of the portion where the top ring of the piston ring adjacent to the cylinder head 17 slides, is maintained uniformly.

On the other hand, during high loads such as when sailing at full power, the switching valve 48
Even if the cylinder block 19 is controlled at a temperature of t2 by opening the valve, the amount of heat generated from the cylinder block 19 is increasing, so there is no risk of sulfuric acid corrosion occurring.

On the other hand, the cylinder head 17 is cooled to a low temperature t2, and the intake port (not shown) of the cylinder head 17a is cooled to a low temperature to improve the filling efficiency of intake air. (not shown) etc. can be reduced.

The materials of the cylinder head 17 and cylinder block 19 are not limited to the case where the cylinder head 17 is made of aluminum alloy and the cylinder block 19 is made of cast iron, but both the cylinder head 17 and cylinder block 19 may be made of aluminum alloy. In this case as well, the cylinder block 19 is
Since the temperature is controlled by thermostat T2, the problem of overcooling does not occur.

Furthermore, cylinder head 17 and cylinder block 1
9 may be integrally molded, and a cooling water jacket 17a for cooling the cylinder head 17 and a cooling water jacket 19a for cooling the cylinder block 19 may be formed separately inside. In this case, since the position of the partition wall between the cooling water jacket 17a and the cooling water jacket 19a can be freely shifted, the temperature of the cylinder head 17 and the cylinder block 19 can be strictly controlled locally. .

Next, a modification of the first embodiment in which the cooling water inlet to the cylinder head 17 is provided upward will be described with reference to FIGS. 2a to 2c. In the case of FIG. 2a, a thermostat T1 is provided at the bottom of the cylinder head 17 to control the outlet temperature of the cooling water jacket 17a. In the case of FIG. 2b, a thermostat T2 is provided at the top of the cylinder block 19 to control the outlet temperature of the cooling water jacket 19a. Furthermore, in FIG. 2c, seawater is made to flow from top to bottom through the cooling water jacket 17a of the cylinder head 17, and seawater is made to flow from top to bottom through the cooling water jacket 19a of the cylinder block 19. .

Further, a second embodiment of the present invention will be described with reference to FIG. In FIG. 3, parts given the same reference numerals as those in FIG. 2 indicate the same or equivalent parts.

FIG. 3 shows a case in which the cooling water inlet of the cooling water jacket 17a is provided below, and the direction of seawater flow is upward from the bottom to the top. In this way, the cooling water jacket 17a and the cooling water jacket 19a
If both seawater flow directions are directed upward, there is no risk of air remaining in the middle of the cooling water jackets 17a and 19a, which is advantageous in terms of air removal.

3a shows a case where a thermostat T1 is provided on the top of the cylinder head 17, and FIG. 3b shows a case where a thermostat T2 is provided on the top of the cylinder block 19.
This shows the case where .

Furthermore, FIG. 3c shows how the cooling water is transferred to the cooling water jacket 17.
A has cooling water jacket 1, which is circulated from bottom to top.
The cooling water discharged from 7a is transferred to the cooling water jacket 1.
The case is shown in which the liquid is distributed from the top to the bottom of 9a.

(Effects of the Invention) As explained above, the engine cooling device according to the present invention is capable of supplying cooling water to the cylinder head in an engine in which the crankshaft is arranged vertically and the cylinder head and cylinder block are arranged horizontally in parallel. If the jacket and cylinder block cooling water jackets are formed separately and a thermostat is installed to individually control the cooling water temperature of each cooling water jacket, the cylinder head 17 can be cooled as shown in FIG. cooling water jacket 1
7a and the cooling water jacket 19a are separated and their temperatures are controlled individually by thermostats T1 and T2, and the cylinder head 1 to be cooled to a low temperature is
Cylinder block 7 is cooled to a low temperature t2, while cylinder block 19, on the other hand, is at a relatively high temperature. It can be cooled at a temperature of t3.

Therefore, the temperature of the intake port of the cylinder head 17 becomes low, improving the filling efficiency of intake air, and the cylinder liner of the cylinder block 19 is kept at a high temperature, improving engine performance. The amount of liner wear is reduced.

Since the cooling water inlet becomes low temperature and the outlet becomes high temperature, there is a problem that uneven temperature occurs in various parts of the engine.
An embodiment that eliminates this drawback is the embodiment shown in FIGS. 2 and 3. In the case of Figures 2 and 3, the cooling water is passed in one vertical direction through the cooling water jacket of the cylinder head, and the cooling water after cooling the cylinder head is distributed through the cooling water jacket of the cylinder block. Therefore, the cylinder head 17
is cooled with low-temperature cooling water, and the cylinder head 17
Since the coolant heated by the cooling water flows into the cylinder block 19, the cylinder liner can be kept at an appropriate temperature, and the above-mentioned effects can be further enhanced. Therefore, this embodiment is effective in increasing the cylinder temperature when the amount of heat dissipated is small, such as during idling.

As shown in FIG. 2, when cooling water flows from above to below the cooling water jacket 17a of the cylinder head 17, convection occurs inside the cylinder head 17a, and the stagnant cooling water is heated and warmed. The temperature rises toward the cooling water inlet 17b at the top of the jacket, and the temperature at the cooling water inlet 17b becomes higher than t0 despite the entrance, becoming t0 + α, and the temperature difference with the cooling water outlet 17c becomes smaller, so each part of the engine is uniform. has the advantage of being cooled. Furthermore, the same applies to the cylinder block side, and the second
Figures 3c and 3c are examples of embodiments that exhibit this advantage.

When cooling water is made to flow from the bottom to the top in the cylinder head cooling water jacket, and cooling water after cylinder head cooling is made to flow from the bottom to the top in the cylinder block cooling water jacket, This has the advantage that there is no risk of air remaining in the middle of both cooling water jackets, making it easier to bleed air.

(Another Embodiment) (1) The present invention is not limited to application to diesel engine outboard motors as described above, but is also applicable to gasoline engines etc. that are used with at least the crankshaft 15 vertically disposed. Applicable to other engines. However, when applied to a diesel engine outboard motor, problems such as the aforementioned sulfuric acid corrosion can be solved, making it optimal.

[Brief explanation of drawings]

Figure 1 is a structural diagram of a diesel engine outboard motor equipped with a diesel engine, Figure 1a, Figure 1
Figure b is a structural diagram showing the basic structure of the cooling system, Figure 2 is a structural diagram showing the first embodiment of the cooling system for a diesel engine, Figures 2a, 2b, and 2c.
3 is a structural diagram showing a modification of the first embodiment shown in FIG. 2, FIG. 3 is a structural diagram showing a second embodiment of the cooling system, and FIGS.
It is a structural diagram showing a modification of the second embodiment shown in the figure.
16... Diesel engine, 17... Cylinder head, 19... Cylinder block, 17a...
Cooling water jacket, 19a...Cooling water jacket, 17b...Cooling water inlet, 17c...Cooling water outlet, 19b...Cooling water inlet, 19c...Auxiliary cooling water outlet, T1, T2...Thermostat.

Claims (1)

[Claims] 1 In an engine in which the crankshaft is arranged vertically and the cylinder head and cylinder block are arranged horizontally in parallel, the cooling water jacket for the cylinder head and the cooling water jacket for the cylinder block are formed separately, and the cooling water jackets for each are separated. A cooling system for a seawater directly cooled marine engine, which is equipped with a thermostat that individually controls the temperature of the cooling water in the water jacket, and allows seawater after cooling the cylinder head to flow through the cooling water jacket of the cylinder block.