JPH0444834Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention relates to a cylinder cooling device for a forced air-cooled engine.It has a simple structure, uniformizes the temperature distribution of the cylinder, and reduces the performance and durability caused by thermal distortion of the cylinder. In addition, parts other than the cylinder head can be used in common between forced air-cooled engines with fully oil-cooled or partially oil-cooled cylinder heads and forced air-cooled engines with forced air-cooled cylinder heads. 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 terms of reducing the weight of the engine. The mainstream of 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, engines have been designed to improve their performance. For this reason, overhead valve engines that use forced air cooling are becoming popular. These forced air-cooled overhead valve engines, which replace conventional forced air-cooled side valve engines, require both high output and low cost. A tappet and a push rod are arranged, and the intake valve and exhaust valve are driven to open via a rocker arm. In this case, in order to reduce the size of the engine, it is customary to form a push rod chamber on one side of the cylinder via a partition wall 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 an engine in which the push rod chamber is formed on one side of the cylinder block through a partition wall, as described above, the partition wall receives combustion heat directly, while the partition wall receives combustion heat directly from the push rod chamber. Since the partition wall is isolated from the cooling air path, the temperature of the partition wall increases and the temperature distribution in the circumferential direction of the cylinder becomes uneven, which may cause thermal strain 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.

The present invention was developed in consideration of the above-mentioned circumstances, and it is possible to equalize the temperature distribution in the circumferential direction of the cylinder with a simple configuration, and to prevent the reduction in output and durability due to thermal distortion of the cylinder. In addition, forced air cooling allows parts other than the cylinder head to be shared between forced air-cooled engines with fully oil-cooled or partially oil-cooled cylinder heads and forced air-cooled engines with forced air-cooled cylinder heads. The object of the present invention is to provide a cylinder cooling device for an engine.

<Means for Solving the Problems> The cylinder cooling device for a forced air-cooled engine according to the present invention has a thick wall portion extending vertically on one side of the cylinder block of the engine, and a thick wall portion extending vertically within the thick wall portion. A cooling oil jacket and a push rod chamber which are open at the upper end surface of the cylinder block are formed adjacent to each other, the cooling oil jacket is connected to an oil pump, and the upper ends of the cooling oil jacket and the push rod chamber are communicated with each other. A communication path is formed between the cylinder block and the head block, and the lower part of the push rod chamber is communicated with the oil pan.

The communication passage may be formed by simply partially removing the gasket inserted between the upper end surface of the cylinder block and the lower end surface of the head block, or by recessing a portion of the upper end surface of the cylinder block.

<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 jacket in the thick walled part of the cylinder block, and after cooling this high temperature part, It flows from the upper end through the communication path to the push rod chamber, and is further returned to the oil pan from the lower part of the cooling oil return path.
In this way, since the high temperature portion is cooled by the cooling oil, the temperature distribution in the circumferential direction of the cylinder is made uniform, and the occurrence of thermal strain in the cylinder is prevented. As a result, a decrease in output and durability due to thermal distortion of the cylinder is prevented.

In addition, the conventional push rod chamber is used as the path for returning the cooling oil that partially cools the cylinder to the oil pan, and only a cooling oil jacket connected to the oil pump is added, so the configuration is simplified. Simple, easy, and inexpensive to implement.

Furthermore, since the cooling oil jacket and the push rod chamber extend to the upper end surface of the cylinder block, for example, a full oil-cooled cylinder having a cooling oil inlet passage and a cooling oil outlet passage opening opposite to the cooling oil jacket and push rod chamber can be used. By assembling a type or partial oil-cooled cylinder head, the cooling oil jacket can be used as the cooling oil supply path to the cylinder head, and the push rod chamber can be used as the cooling oil return path from the cylinder head, excluding the cylinder head. Other parts can be used in both a forced air-cooled engine having a fully oil-cooled or partially oil-cooled cylinder head and a forced air-cooled engine.

<Embodiment 1> Hereinafter, one embodiment 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 front of the cooling fan 7 and the engine is covered with a wind guide case 8, and the air taken in by the cooling fan 7 from the air intake port 9 formed at the front of the wind guide case 8 is guided to the wind guide case 8 as cooling air. It is then supplied to the cylinder block 2 and head block 3 of the engine. Also, crank case 1
A trochoid type lubricating oil pump 10 is installed on the rear wall 1a.
will be incorporated. 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 through an oil strainer 13 and supplied to each part of the engine through a lubricating oil supply path 14 formed inside the crankshaft 4 and the like.

From the middle of this lubricating oil supply path 14 to the cooling oil outgoing path 1
5 is branched, and this cooling oil outgoing path 15 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. A push rod chamber 19 is formed on one side of the cylinder block 2, and a cooling oil outgoing path 15 is provided inside a partition wall 16 that partitions the push rod chamber 19 and the cylinder 25.
A cooling oil jacket 18 is formed which is communicated with through a relief valve 17. Inside the push rod chamber 19 are an upper part of a tappet 21 that moves up and down according to the cam 20 of the valve drive camshaft 6, and a tappet 21 that moves up and down according to the cam 20 of the valve drive camshaft 6.
A push rod 22, which abuts against the upper end of the tappet 1 and moves up and down together with the tappet 21, is inserted. The cooling oil jacket 18 and the push rod chamber 19 each extend to the upper end surface of the cylinder block 2 and are opened there. The upper end of this cooling oil jacket 18 is communicated with the upper end of the push rod chamber 19 via a communication passage 23 formed by recessing the lower surface of the head block 3 in the portion facing the cooling oil jacket 18 into an inclined surface shape. . An oil return hole 24 communicating with the crankcase 1 is formed in the bottom wall of the push rod chamber 19. An oil return hole and blazer passage 29 is formed on the front side of the cylinder 25 to communicate the crank room 26 in the crank case 1 with the rocker arm chamber 28 in the head cover 27. Furthermore, the communicating passage 23 is formed at the same time as the cylinder head 3 is cast.

In the above structure, the head block 3 and cylinder block 2 as a whole are forcedly cooled by cooling air supplied by a cooling fan 7 and guided by an air guide case 8. The partition wall 16 directly receives the combustion heat in the cylinder 25, and
Since it is isolated from the cooling air path by the push rod chamber 19, if it is cooled only by forced air cooling, the temperature will become higher than other parts of the cylinder block 2, and the temperature distribution in the circumferential direction of the cylinder 25 will become uneven. Become. However, by cooling the partition wall 16 with lubricating oil, the partition wall is prevented from increasing in temperature, and the temperature distribution in the circumferential direction of the cylinder 25 is maintained uniform. That is, the oil pan 12
After the lubricating oil inside is filtered by an oil strainer 13, it is supplied to each part of the engine via a lubricating oil supply path 14 by a lubricating oil pump 10.
On the other hand, the cooling oil is led to the cooling oil jacket 18 of the partition wall 16 through the cooling oil outgoing path 15. Then, while passing through the cooling oil jacket 18, heat storage in the partition wall 16 is taken away,
The partition wall 16 is cooled. The lubricating oil pushed up to the upper end of the cooling oil jacket 18 is sent out from the communication passage 23 to the push rod chamber 19, and then passes through the oil return hole 24.
The oil is returned to the oil pan 12 in the crankcase 1 through the In this way, the heat accumulated in the thick wall portion 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 25 is maintained uniform. In this way, thermal distortion of the cylinder 25 is prevented from occurring, and a decrease in output and durability due to thermal distortion of the cylinder 25 is prevented.

In addition, the conventionally provided push rod chamber 19 is used as a path for returning the lubricating oil used for cooling the cylinder 25, and the cooling oil outgoing path 1
5. It is only necessary to add the cooling oil jacket 18 and the communication passage 23, and this communication passage 23 can be easily formed by changing the pattern of the gasket or forming a recess in the bottom of the head block. It has a simple structure and can be implemented easily and inexpensively.

Furthermore, since the cooling oil jacket 18 and the push rod chamber 19 extend to the upper end surface of the cylinder block 2, the cylinder block 2 of this engine has excellent durability and quietness as shown in FIGS. 5 to 7. Oil-cooled head block 3
0 can be installed.

That is, this head block 30 has a cooling oil introduction passage 31 that opens opposite to the cooling oil jacket 18.
, a cooling oil passage 33 that communicates with this and is formed around a portion that becomes relatively high temperature, such as the auxiliary chamber 32 , and a cooling oil passage 33 that further communicates with this and opens opposite the cooling oil jacket 18 . It has an oil outlet path 34. The cooling oil passage 33 and the cooling oil outlet passage 34
An oil cooler 35 is connected as necessary between the If a sufficient amount of heated lubricating oil is mixed with other lubricating oils in the oil pan 12 and sufficiently cooled, deterioration of the lubricating oil due to heat can be prevented for a sufficiently long period of time, so this oil The cooler 35 can be omitted. The oil cooler 35 is cooled by a portion of the cooling air supplied from the cooling fan 7 and guided by the air guide case 8 as needed. still,
Cooling is supplied from the cooling fan 7 to relatively low-temperature parts of the headblock 3, such as the peripheral wall of the intake port 34, the peripheral wall of the exhaust port 35, and the upper wall of the main combustion chamber 40 having the intake valve seat 32 and the exhaust valve seat 33. and is forcedly cooled by cooling air guided by the air guide case 8.

In this way, by making most parts except the headblock common between a forced air-cooled engine with a fully forced air-cooled headblock and an engine with a fully oil-cooled or partially oil-cooled headblock, it is possible to select the headblock to be assembled. This makes it possible to easily create multiple types of engines with different cooling methods.

Embodiment 2 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.

In this embodiment, a communication passage 23 is formed between the head block 3 and the cylinder block 2 by cutting out a portion of the gasket 41 inserted between the head block 3 and the cylinder block 2. The rest of the structure is similar to the above embodiment shown in FIGS. 1 to 4.

In the above configuration, the lubricating oil supplied to the cooling oil jacket 18 cools the thick walled portion 16 and then flows into the push rod chamber 19 through the communication path 20 between the head block 3 and the cylinder block 2.
The oil is returned to the oil pan 12 through the oil return hole 24. Therefore, the heat accumulated in the thick wall portion 16 is absorbed by the lubricating oil and removed, thereby preventing the thick wall portion 16 from increasing in temperature, making the temperature distribution in the circumferential direction of the cylinder 21 uniform, and reducing thermal distortion of the cylinder 21. It is possible to prevent this occurrence and prevent a decrease in output and durability due to thermal distortion of the cylinder 21. Further, in this case, since the communication path 23 is formed by changing the pattern of the gasket 41 between the head block 3 and the cylinder block 2, the communication path 23 is formed by changing the pattern of the gasket 41 between the head block 3 and the cylinder block 2. It can be implemented easily and at low cost. Of course, as in the above embodiment, a partially oil-cooled headblock 30 as shown in FIGS. 5 to 7 can be attached to the cylinder block 2 in place of the headblock 3.

In this case, by limiting the cross-sectional area of the communication passage 20 to a predetermined size, the communication passage 20 can be given the function of the relief valve 17. If the function is provided, the relief valve 17 can be omitted and the discharge pressure of the lubricating oil pump 10 can be controlled by the flow passage cross-sectional area of the communication passage 20.

<Effects of the Invention> As described above, according to the present invention, by circulating cooling through the cooling oil jacket formed in the thick-walled part and the push rod chamber, more cooling is transmitted to the thick-walled part than to other parts of the cylinder block. Since the heat is absorbed by the cooling oil, the temperature distribution in the circumferential direction of the cylinder is made uniform, and thermal distortion of the cylinder is prevented. As a result, deterioration in output and durability due to thermal distortion of the cylinder is prevented.

In addition, in addition to utilizing the push rod chamber conventionally provided in the return oil path for cooling oil that cools thick-walled parts, a cooling oil jacket connected to the oil pump and a cooling oil jacket and push rod chamber adjacent to this are used. The structure is simple and can be implemented easily and at low cost since it is only necessary to add a communication path that communicates the upper parts of the two to the conventional structure.

Furthermore, since the cooling oil jacket and the push rod chamber extend to the upper end surface of the cylinder block, a fully oil-cooled or partially oil-cooled head block having a cooling oil inlet passage and a cooling oil outlet passage opening opposite to these can be used. It is possible to improve durability and quietness by assembling the engine, and parts other than the headblock of an engine with a forced air-cooled headblock can be used with an engine with a fully oil-cooled or partially oil-cooled headblock. It is possible to reduce costs by standardizing the

[Brief explanation of the drawing]

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
6...Thick wall part, 18...Cooling oil jacket, 19
...Pushing room, 23...Communication passage, 25...
…Cylinder.

Claims (1)

[Scope of utility model registration request] A push rod chamber 19 extending vertically is formed on one side of the cylinder block 2 of the engine.
A cooling oil jacket 18 is formed that opens at the upper end surface, and the cooling oil jacket 18 is connected to the oil pump 10, and these cooling oil jackets 18 are connected to the oil pump 10.
A communication passage 23 is formed between the cylinder block 2 and the head block 3 to communicate the upper ends of the push rod chamber 19 and the push rod chamber 19, and the lower part of the push rod chamber 19 is communicated with the oil pan 12. Cylinder cooling system for air-cooled engines.