JPH0444833Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention relates to a cylinder block cooling device for a forced air-cooled engine, which can uniformize the temperature distribution of the cylinder and prevent deterioration in performance and durability due to thermal distortion of the cylinder. It is intended to do so.

<Prior Art> As an engine cooling method, a forced air cooling method has a simple structure, is inexpensive, and is advantageous in reducing the weight of the engine. The mainstream of such forced air-cooled engines has been side-valve engines, which have a simple cylinder head shape and structure, and a simple valve train configuration, but in recent years, in order to improve engine performance, Overhead valve engines that use forced air cooling are becoming more popular. In this way, forced air-cooled overhead valve engines that replace conventional forced air-cooled side valve engines are required to have high output as well as low cost and size, so the valves are usually installed in the crank room. A camshaft is disposed, a tappet and a push rod are disposed on one side of the cylinder, and the intake valve and exhaust valve are driven to open via a rocker arm pivotally supported by the headblock. In this case, in order to downsize the engine, it is customary to form a push rod chamber on one side of the cylinder into which the push rod is inserted, and to minimize the distance between the center of the cylinder and the tappet or push rod. .

<Problems to be solved by the invention> However, in the engine in which the push rod chamber is formed on one side of the cylinder block as described above, the partition wall that partitions the cylinder and the push rod chamber is exposed to the high temperature of the combustion chamber on one side, and exposed to the high temperature on the other side. In this case, since the push rod chamber is isolated from the cooling air, the temperature of the partition wall becomes high, and the temperature distribution on the cylinder wall becomes uneven, which may cause thermal strain in the cylinder. In addition to the partition wall between the cylinder and the push rod chamber, other parts of the cylinder block where the cooling air is blocked by other parts, etc., where the amount of cooling air is small, are also likely to become hot, and such local areas As the temperature increases, the temperature distribution on the cylinder wall becomes uneven, and there is a risk that thermal distortion will occur in the cylinder. This problem becomes particularly noticeable in engines that are designed to achieve high performance, as the amount of heat generated by the engine is large. Such thermal strain impairs the adhesion between the cylinder inner circumferential surface and the piston ring, resulting in a decrease in output and uneven wear of the cylinder inner circumferential surface, thereby reducing durability.

Up to now, there has been no attempt to specifically cool high-temperature parts such as the partition wall between the cylinder and the push rod chamber in an overhead valve type forced air-cooled engine to prevent thermal distortion of the cylinder.

The present invention was developed in consideration of the above-mentioned circumstances, and is a forced air-cooled engine that aims to equalize the temperature distribution on the cylinder wall and prevent a decrease in output and durability due to thermal distortion of the cylinder. The object of the present invention is to provide a cylinder cooling device.

<Means for Solving the Problems> The cylinder block cooling device for a forced air-cooled engine according to the present invention forms a cooling oil outgoing path extending vertically in a relatively high-temperature section of the cylinder block of the engine. A cooling oil return path extending vertically is formed at an appropriate location on the block, and the cooling oil outgoing path is connected to the oil pump.
The cooling oil outward passage and the cooling oil return passage are characterized in that their upper ends communicate with each other on the joint surface between the cylinder block and the head block, and the lower part of the cooling oil return passage communicates with the oil pan.

High-temperature parts include parts that are exposed to high temperatures and are heated more than other parts, parts that tend to lack cooling air and are difficult to cool, and parts that are heated more than other parts and are difficult to cool. Conceivable. For example, the partition wall that separates the cylinder from the push rod chamber is typically a part that is heated more than other parts and is more difficult to cool.

For example, when the cooling oil outgoing path is formed in a partition wall that partitions the cylinder and the push rod chamber, it is advantageous to form the cooling oil return path in the push rod chamber because the structure can be simplified.

When the upper ends of the cooling oil outward path and the cooling oil return path are communicated with each other on the joint surface of the cylinder block and head block, it is only necessary to partially remove the gasket inserted between the upper end surface of the cylinder block and the lower end surface of the head block. Alternatively, or in addition to this, one or both of a portion of the upper end surface of the cylinder block and a portion of the lower end surface of the head block may be recessed.
If a recess is not formed on the upper end surface of the cylinder block, the above cooling oil outgoing path and cooling oil return path can be changed to the cooling oil outgoing path and cooling oil return path to the oil-cooled cylinder head without making any changes to the cylinder block, etc. This makes it easier to share parts such as cylinder blocks and gaskets with the exception of head blocks between engines with fully forced air-cooled cylinder heads and engines with fully oil-cooled or partially oil-cooled cylinder heads. can.

<Operation of the invention> In the cylinder cooling system for a forced air-cooled engine configured as described above, cooling oil is supplied from the oil pump to the cooling oil outgoing path in the high temperature section in the circumferential direction of the cylinder block where the temperature is relatively high. After the cooling oil has been cooled, it flows from its upper end to the cooling oil return passage, and is further returned to the oil pan from the lower part of the cooling oil return passage. In this way, the high-temperature parts are cooled by the cooling oil, so the temperature distribution in the circumferential direction of the cylinder is made uniform.
Thermal distortion of the cylinder is prevented. the result,
This prevents a decrease in output and durability due to thermal distortion of the cylinder.

In addition, since the upper ends of the cooling oil outward path and the cooling oil return path are communicated with each other on the joint surface between the cylinder block and the head block, the communication structure between the cooling oil outward path and the cooling oil return path can be simplified, and an increase in cost can be minimized. It can be done to the extent possible.

Furthermore, since the upper ends of the cooling oil outward path and the cooling oil return path are communicated with each other on the joint surface of the cylinder block and the head block, the above-mentioned cooling oil outward path and the cooling oil return path can be connected by simply closing this communication structure with, for example, a gasket. It can be used both as a cooling oil outward path and a cooling oil return path to an oil-cooled cylinder head, and can be used as a head block between an engine with a fully forced air-cooled cylinder head and an engine with a fully oil-cooled or partially oil-cooled cylinder head. The parts except for can be easily shared.

<Example 1> Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 to 7.

FIG. 1 is a vertical cross-sectional rear view of the cylinder block and cylinder head of a forced air-cooled direct injection diesel engine to which an embodiment of the present invention is applied, FIG. 2 is a vertical cross-sectional side view of the engine, and FIG. Fig. 4 is a rear view of the engine, Fig. 4 is a plan view of the cylinder block, Fig. 5 is a longitudinal sectional side view of a forced air-cooled pre-chamber diesel engine with only the head block rearranged, and Fig. 6 is a side view of the forced air-cooled pre-chamber diesel engine. 7 is a longitudinal cross-sectional rear view of the cylinder block and cylinder head, and FIG. 7 is a cross-sectional plan view taken along the line A--A in FIG. 6.

The forced air-cooled direct injection diesel engine shown in Figures 1 to 4 has a crankcase 1 and a cylinder block 2 that are integrally cast from aluminum alloy.
A head block 3 made of aluminum alloy is connected to the upper side of the head block 3. A crankshaft 4, a balancer shaft 5, and a valve drive camshaft 6 are each pivotally supported on the crankcase 1. A front end 4a of the crankshaft 4 projects forward of the crankcase 1, and a cooling fan 7 is fixed to the front end 4a of the crankshaft 4. The cooling fan 7 and the front of the engine are covered with an air guide case 8.
Air taken in by the cooling fan 7 through an air intake port 9 formed at the front of the engine is guided as cooling air to an air guide case 8 and supplied to the cylinder block 2 and head block 3 of the engine. In addition, a trochoid type lubricating oil pump 1 is mounted on the rear wall 1a of the crankcase 1.
0 is included. This lubricating oil pump 10 is interlocked with the crankshaft 4 via a gear device 11, and is connected to an oil pan 12 formed at the bottom of the crankcase 1.
The lubricating oil is pumped up from the engine through an oil strainer 13 and supplied to each part of the engine through a lubricating oil supply path 14 formed inside the rear wall 1a of the crankcase 1, the crankshaft 4, etc. has been done.

A cooling oil supply passage 15a branches off from the middle of this lubricating oil supply passage 14, and this cooling oil supply passage 15a is
It passes through the rear wall 1a of the crankcase 1 and is led to the lower part of one side of the cylinder block 2. Inside one side of the cylinder block 2, there is an upper part of a tappet 18 that moves up and down according to the cam 17 of the valve drive camshaft 6;
A push rod chamber 20 is formed which abuts the upper end of the tappet 18 and into which a push rod 19, which moves up and down together with the tappet 18, is inserted. A cooling oil outgoing path 15 extending in the vertical direction is formed within the partition wall 16 that partitions the push rod chamber 20 and the cylinder 21. The cooling oil outgoing path 15 and the push rod chamber 20 extend to the joint surface between the cylinder block 2 and the head block 3. Further, the width of the cooling oil outward passage 15 along the peripheral wall 22 of the cylinder 21 is formed to be slightly narrower than that of the push rod chamber 20. The upper end of this cooling oil outgoing path 15 is covered by the lower end surface of the head block 3, and is communicated with the upper end of the push rod chamber 20 via a notch 23 formed as necessary in the upper end surface of the cylinder block 2. . This push rod room 20
An oil return hole 24 communicating with the crankcase 1 is formed in the bottom wall of the engine. That is, the push rod chamber 20 is configured to function as a cooling oil return path 20 for returning cooling oil to the oil pan 12. Furthermore, on the front side of the cylinder 21, there is a crank room 25 in the crank case 1 and a head cover 26.
An oil return hole/blazer passage 28 communicating with the rocker arm chamber 27 inside is formed.

In the above configuration, the head block 3 and the cylinder block 2 as a whole are forcedly cooled by cooling air supplied by the cooling fan 7 and guided by the air guide case 8, but the partition wall 16
directly receives the combustion heat in the cylinder 21, and is isolated from the cooling air passage by the push rod chamber 20, so it cannot be cooled by forced air cooling. Therefore, in a cooling system using only forced air cooling, the partition wall 16 essentially constitutes a high-temperature part, and the temperature distribution in the circumferential direction of the cylinder 21 becomes non-uniform. However, this rise in temperature of the partition wall 16 is prevented by the lubricating oil, and the temperature distribution in the circumferential direction of the cylinder 21 is maintained uniform. That is,
The lubricating oil in the oil pan 12 is contained in the oil strainer 1
After being filtered by the lubricating oil pump 10,
On the one hand, it is supplied to each part of the engine via the lubricating oil supply path 14, and on the other hand, it is guided to the partition wall 16 through the cooling oil supply path. Then, while rising in the cooling oil outward path 15, heat is taken away from the partition wall 16, and the notch 2
3 to the cooling oil return path 20, and further to the oil return hole 2.
4 to the oil pan 12 inside the crankcase 1.
will be returned to. In this way, the heat accumulated in the partition wall 16 is absorbed by the lubricating oil and removed, so that the thick wall portion 16
temperature rise is prevented, and the temperature distribution in the circumferential direction of the cylinder 21 is maintained uniform. In this way, thermal distortion of the cylinder 21 is prevented from occurring, and a decrease in output and durability due to thermal distortion of the cylinder 21 is prevented.

The structure for communicating the cooling oil outward path 15 and the cooling oil return path 20 is a simple structure in which a notch 23 is formed in the upper end surface of the partition wall 16, and is suitable for drilling, milling, etc. Therefore, it can be easily formed.

Furthermore, since the cooling oil outward passage 15 and the cooling oil return passage 20 extend to the upper end surface of the cylinder block 2, a partially oil-cooled headblock 30 as shown in FIGS. 5 to 7 is installed in the cylinder block 2 of this engine. Assembling allows for even higher output and quieter operation. In this case, the above notch 2
No. 3 is formed without forming a cooling oil outward path 15 and a cooling oil return path 20.
and are configured to open at the upper end surface of the cylinder block 2 independently of each other. The head block 30 also has a cooling oil introduction passage 37 that opens opposite to the cooling oil outgoing passage 15, and a cooling oil introduction passage 37 that is formed around a relatively high temperature portion such as the auxiliary chamber 31 that communicates with the cooling oil introduction passage 37. A cooling oil passage 36 and a cooling oil outlet passage 39 which communicates with this passage and opens opposite to the push rod chamber 20 are formed. An oil cooler 38 is connected between the cooling oil passage 36 and the cooling oil outlet passage 39 as required. This oil cooler 38
is cooled by a portion of the cooling air supplied from the cooling fan 7 and guided by the air guide case 8, for example. Note that if the amount of oil supplied to the cooling oil path 36 is sufficiently large and the temperature rise of the lubricating oil is relatively small,
Alternatively, if the total amount of lubricating oil is sufficiently large and the heated lubricating oil is mixed with other lubricating oils and sufficiently cooled, deterioration of the lubricating oil due to heat can be prevented for a sufficiently long period of time. This oil cooler 3
8 can be omitted. Also, the relatively low temperature part of the headblock 3, that is, the intake port 3
4 peripheral wall, exhaust port 35 peripheral wall, intake valve seat 32
The upper wall of the main combustion chamber 40 having the exhaust valve seat 33 and the like are forcedly cooled by cooling air supplied from the cooling fan 7 and guided by the air guide case 8.

<Embodiment 2> FIG. 8 is a longitudinal sectional rear view of a cylinder block and cylinder head of a forced air-cooled direct injection diesel engine to which another embodiment of the present invention is applied.

In this embodiment, the notch 23 is not formed on the upper end surface of the cylinder block 2, and the head block 3 is
Cooling oil outgoing path 15 and push rod chamber 2 on the lower surface of the
0 is recessed in the shape of an inclined surface, and the upper end of the cooling oil outgoing path 15 and the upper end of the push rod chamber 20 are communicated via this recessed portion 29. The rest of the structure is similar to that of the above embodiment shown in FIGS. 1 to 4.

In the above configuration, the lubricating oil supplied to the cooling oil outgoing path 15 cools the partition wall 16 and then passes through the recessed part 29 of the head block 3 to the push rod chamber 2.
0 and is returned to the oil pan 12 through the oil return hole 24. Therefore, by absorbing the heat accumulated in the partition wall 16 into the lubricating oil and removing it, the temperature of the partition wall 16 is prevented from increasing, the temperature distribution in the circumferential direction of the cylinder 21 is made uniform, and the occurrence of thermal distortion in the cylinder 21 is prevented. , it is possible to prevent a decrease in output and durability due to thermal distortion of the cylinder 21. Of course, it is possible to install a partially oil-cooled headblock 30 as shown in FIGS. 5 to 7 in place of the headblock 3 to the cylinder block 2.

<Effects of the invention> As described above, according to the invention, a cooling oil outgoing path and a cooling oil return path extending vertically are formed in the high temperature part of the cylinder, and cooling oil is supplied to the cooling oil outgoing path and the cooling oil return path. By circulating, the heat stored in the high temperature portion is absorbed by the cooling oil, so that the temperature distribution in the circumferential direction of the cylinder is made uniform, and the occurrence of thermal distortion in the cylinder is prevented. As a result, deterioration in output and durability due to thermal distortion of the cylinder is prevented.

Furthermore, since the upper ends of the cooling oil outward path and the cooling oil return path are communicated with each other on the joint surface between the cylinder block and the head block, for example, a portion of the upper end surface of the cylinder block or a portion of the lower end surface of the head block may be recessed. , the structure of the communication part between the cooling oil outgoing path and the cooling oil return path can be simply configured, such as by cutting out a part of the gasket inserted between the cylinder block and the head block, and it is easy to do so. It can be implemented inexpensively.

Furthermore, since the cooling oil outward path and the cooling oil return path extend to the joint surface between the cylinder block and the head block, it is possible to use a fully oil-cooled type or a partially oil-cooled type with a cooling oil inlet path and a cooling oil outlet path that open opposite to these. A cooled headblock can be installed to improve durability and quietness, and the headblocks of engines with fully oil-cooled or partially oil-cooled headblocks and those with forced air-cooled headblocks can also be installed. It is possible to reduce costs by standardizing parts other than .

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional rear view of the cylinder block and cylinder head of a forced air-cooled direct injection diesel engine to which an embodiment of the present invention is applied, Fig. 2 is a longitudinal cross-sectional side view of the engine, and Fig. 3 is a rear view of the engine. Figure 4 is a plan view of the cylinder block, Figure 5 is a longitudinal side view of a forced air-cooled pre-chamber diesel engine with only the head block rearranged, and Figure 6 is a longitudinal rear view of the cylinder block and cylinder head. , Figure 7 is A-A in Figure 6.
FIG. 8 is a vertical cross-sectional rear view of the cylinder block and cylinder head of a forced air-cooled direct injection diesel engine to which another embodiment of the present invention is applied. 2... Cylinder block, 3... Head block, 10... Oil pump, 12... Oil pan, 1
5...Cooling oil outward path, 16...High temperature section (bulkhead), 1
9... Push rod, 20... Cooling oil return path (push rod room).

Claims (1)

[Scope of utility model registration request] A cooling oil outgoing path 15 extending vertically is formed in the high temperature part 16 of the cylinder block 2 of the engine, which becomes relatively high temperature, while a cooling oil return path 20 extending vertically is formed at an appropriate location of the cylinder block 2 to cool the cylinder block 2. The oil outgoing path 15 is connected to the oil pump 10, and the cooling oil outgoing path 15 and the cooling oil return path 20 are connected to each other.
This cylinder block cooling device for a forced air-cooled engine is characterized in that the upper ends of the cylinder block 2 and the head block 3 are connected to each other on the joint surface of the cylinder block 2 and the head block 3, and the lower part of the cooling path return path 20 is connected to the oil pan 12.