JPH036326B2 - - 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 system that prevents overcooling of the cylinder block.

(Objective of the Invention) An object of the present invention is to provide an engine cooling device that can sufficiently cool a cylinder head that generates a large amount of heat, prevent overcooling of the cylinder block, and also make the entire device compact and simple. It is an object.

(Structure of the Invention) In the present invention, the cooling water jacket 17a of the cylinder head 17 and the cooling water jacket 19a of the cylinder block 19 are formed separately, and each cooling water jacket has a cooling water inlet 17b, 19b and an outlet 17c. , 19c so that the cooling water from the cooling water supply pump 28 flows through the cooling water jacket 17a of the cylinder head 17 and into the cooling water jacket 19a of the rear cylinder block 19.
This is an engine cooling device characterized in that the pump 28 is connected to the cooling water jacket inlet 17b of the cylinder head 17, and the cooling water jacket inlet 19b of the cylinder block 19 is connected to the cooling water jacket outlet 17c of the cylinder head 17. .

(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 bracket 12 is attached to the rearmost part of the hull 10.
A diesel engine outboard motor 14 is attached via. The diesel engine outboard motor 14 has a structure that combines a diesel engine 16 and a drive unit 18. The diesel engine 16 is covered with a cowling 20, and the drive unit 18 is covered with a cowling 20.
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 set to t2.
This is a case where 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 is provided at the upper end of the cooling water jacket 19a.
A main cooling water outlet 19d is provided, 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 a passage 44 is connected to the thermostat T2, and the other end of the passage 44 is connected to the passage 30 (FIG. 1).

When the thermostat T1 (valve opening temperature t2) is provided near the main cooling water outlet 19d as described above, one end of the passage 46 is connected to the thermostat T1, and the other end of the passage 46 is connected to a part of the passage 44. It is connected to the. 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 flow seawater at a temperature of t2 into the cooling water jacket 19a, and the cylinder block 19 is heated. When the load of the block 19 is low, such as during idling, the switching valve 48 is closed to allow seawater at a temperature of t3 to flow into the cooling water jacket 19a. 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 thermostat T1 is installed at either the cooling water inlet 17b or the main cooling water outlet 19d. establish.

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. 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 flowing into the water jacket 17a increases 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 closes due to the pressure of the seawater. The thermostat T2 of the cylinder block 19 also remains closed, and the seawater remains stagnant. Eventually, the temperature of the jacket 19a increases as it cools down, reaching the temperature t3, and the thermostat T2 opens, and the seawater from the cooling water jacket 17a cools and flows from the inlet 19b to the auxiliary cooling water outlet 19c, and flows through the passage 4.
4 into a passageway 30.

Therefore, at 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 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 even if the temperature is controlled at a relatively low temperature t2.

On the other hand, the cylinder head 17a improves the filling efficiency of intake air by cooling the intake port (not shown) of the cylinder head 17, which has been cooled to a low temperature t2, to a low temperature, and also improves the filling efficiency of the intake air (not shown) between the intake and exhaust valves of the cylinder head 17. ), etc., 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, t
Cooling water inlet 17b from seawater pump 28 at a temperature of 0
The seawater that has flowed into the cooling water jacket 17a mixes with the relatively high temperature seawater that has gathered at the top due to the convection phenomenon in 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 rises with a relatively small temperature gradient from t1 to t2, and when the thermostat T1 of the cylinder head 17 opens at the temperature of t2, the pressure of the seawater opens the check valve 64. Valve, passage 4
2. Passage 3 through passage 66 and bypass passage 50
Ejected to 0.

On the other hand, connect the thermostat T1 to the main cooling water outlet 19d.
When the thermostat T1 near the cooling water outlet 17c is removed, the passage 42 has a short length and can be integrally cast into the cylinder head 17 and the cylinder block 19 by casting.

Eventually, when the temperature of the seawater in the cooling water jacket 19a rises from t2 to t3, the thermostat T
2 opens, 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, there is no risk that the cylinder liner of the cylinder block 19 will undergo the aforementioned sulfuric acid corrosion.

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 17 is cooled to a low temperature to improve the filling efficiency of intake air, so that the cylinder block 19 is cooled to a relatively high temperature t3. In addition, the heat load between the intake and exhaust valves (not shown) of the cylinder head 17 is also reduced.

Regarding the materials of the cylinder head 17 and cylinder block 19 mentioned above, the cylinder head 17
It is also possible to form the cylinder block 19 from an aluminum alloy having a good heat transfer coefficient, and to form the cylinder block 19 from cast iron having a relatively poor heat transfer coefficient.

The cylinder head 17 is not limited to being 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, since the temperature of the cylinder block 19 is controlled by the thermostat T2 during idle, 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, referring to Figures 2a to 2c, the above first
A modification of the embodiment will be described. 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. Further, in FIG. 2c, seawater is made to flow from the bottom to the top through the cooling water jacket 17a of the cylinder head 17, and the cylinder block 1
The cooling water jacket 19a of No. 9 is configured to allow seawater to flow from top to bottom.

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 where the seawater flow direction of the cooling water jacket 17a is upward from the bottom to the top, and the seawater flow direction of the cooling water jacket 19a is upward from the bottom to the top. In this way, the cooling water jacket 17a and the cooling water jacket 1
If the seawater flow directions of the seawater pipes 9a are both directed upward, there is no possibility that air will remain 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 .

(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 and the cooling water jacket 19a of the cylinder block 19, and the cooling water from the pump 28 is first supplied to the cylinder head. 17 cooling water jacket 17
They are connected in series so that the water is introduced into the cooling water jacket 19a of the rear cylinder block 19. This has the following effects.

(A) Since the low temperature cooling water from the pump 28 is first introduced into the cylinder head side cooling water jacket 17a, the effect of cooling the cylinder head 17 is large.
Furthermore, since the coolant whose temperature has been raised is then led to the cylinder block side coolant jacket 19a, sulfuric acid corrosion (occurrence of wear) of the cylinder liner due to overcooling can be prevented.

(B) Since the same cooling water is sequentially used to cool the cylinder head 17 and cylinder block 19, the heat exchanger size is reduced compared to the case where two types of cooling water (fresh water and seawater) are used as in the cited example. This eliminates the need, and the device can be made smaller and simpler.

Furthermore, when the cylinder head 17 is made of an aluminum alloy, the coefficient of thermal expansion of the cylinder head 17 becomes large, and sealing of the joint between the cylinder head 17 and the cylinder block 19 becomes a problem, but the cooling water jacket 17a of the cylinder head 17 Since the cooling water inlet 19b of the cylinder block 19 and the cylinder block 19 are separated, there is no need to form a cooling water passage in the gasket (not shown) between the cylinder head 17 and the cylinder block 19. Corrosion can be prevented, and the gasket only needs to seal combustion gas and lubricating oil, which is advantageous for gasket design. If the cylinder head and cylinder block are made of aluminum alloy, it is very advantageous in reducing the weight of the engine, but on the other hand, due to the difference in thermal expansion coefficient between aluminum alloy and gasket material, and the low rigidity of aluminum alloy, direct cooling in seawater is not possible. It is well known that gasket problems occur frequently. However, if the present invention is adopted, the gasket design is advantageous as mentioned above, and even when directly cooled by seawater, both the cylinder block and the cylinder head are made of aluminum alloy, making it possible to provide a lightweight engine while eliminating gasket troubles. However, since the temperature of the cylinder block 19 is controlled by the thermostat T2, the temperature of the cylinder block 19 can be maintained at an appropriate temperature.

Also, the cooling water jacket 1 of the cylinder head 17
7a and the cooling water jacket 19a of the cylinder block 19 are separated, and a thermostat T1 is provided on the outlet side of the cooling water jacket 17a of the cylinder head 17, so that only the cooling water heated in the cooling water jacket 17a of the cylinder head 17 can be used. is supplied to the cooling water jacket 19a of the cylinder block 19 by the action of the thermostat T1, so that sulfuric acid corrosion of the cylinder liner can be more effectively prevented.

Particularly in cold weather, the temperature of the water entering the cooling water inlet 17b of the cylinder head 17 is low, so there is a high possibility that sulfuric acid corrosion will occur. By providing the cooling water outlet 17c of the cylinder block 19, overcooling of the cylinder block 19 can be reliably prevented and sulfuric acid corrosion can be prevented.

The cylinder head 17 and cylinder block 19 are integrally molded, and a cooling water jacket 17a for cooling the cylinder head 17 and a cylinder block 1 are provided inside.
9. When the cooling water jacket 19a for cooling is formed separately, the position of the partition wall between the cooling water jacket 17a and the cooling water jacket 19a can be freely shifted, so that the cylinder head 17 and the cylinder block 19 can be separated. Partial temperature control can be strictly controlled.

(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]

Fig. 1 is a structural schematic diagram of a diesel engine outboard motor equipped with a diesel engine to which the present invention is applied, Fig. 2 is a structural schematic diagram showing a first embodiment of a cooling system for a diesel engine, Fig. 2a, Fig. 2b,
2c is a structural schematic 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. 3a and 3b are structural diagrams showing a modification of the first embodiment shown in FIG. It is a structural diagram showing a modification of the second embodiment. 16
...Diesel engine, 17...Cylinder head, 19...Cylinder block, 17a...Cooling water jacket, 19a...Cooling water jacket, 1
7b...Cooling water inlet, 17c...Cooling water outlet, 1
9b...Cooling water inlet, 19c...Main cooling water outlet,
T1, T2...Thermostat.

Claims (1)

[Claims] 1. At least the cylinder head 17 is made of aluminum alloy, the cooling water jacket 17a of the cylinder head 17 and the cooling feng shui jacket 19a of the cylinder block 19 are formed separately, and each cooling water jacket is provided with a cooling water inlet 17b, 19b, respectively. and outlets 17c and 19c, and a pump 2 for supplying cooling water.
8 flows through the cooling water jacket 17a of the cylinder head 17 to the rear cylinder block 19.
The pump 28 is connected to the cooling water jacket inlet 17b of the cylinder head 17 so that the water flows into the cooling water jacket 19a of the cylinder block 19.
A cooling water jacket inlet 19b of the engine is connected in series to a cooling water jacket outlet 17c of a cylinder head 17, and a thermostat T1 is provided on the cooling water jacket outlet side of the cylinder head 17.