JP3804215B2 - OHC engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an OHC engine, a cylinder bore, a power transmission means accommodating chamber in which a power transmission means provided on a side of the cylinder bore and transmitting an engine rotational force to a valve opening / closing mechanism in a valve chamber above the cylinder bore is accommodated, The present invention relates to an OHC engine including a cylinder block having
[0002]
[Prior art]
Conventionally, engine cooling methods include a water-cooling method in which cooling water is forcedly circulated in the engine, and a plurality of cooling fins protruding from the engine body so that the outside air has a larger surface area. It can be classified into an air-cooled type that cools by touching.
[0003]
A water-cooled engine can actively cool a part where the amount of heat generated is large by setting the size and position of the water jacket to an appropriate position. Therefore, the structure is complicated and the number of processes for manufacturing the engine is large, and additional equipment such as a radiator and a radiator pump is required, resulting in high costs.
[0004]
On the other hand, the air-cooled engine has a simple engine body structure, a small number of manufacturing steps, and does not require any auxiliary equipment for cooling, so that the cost can be reduced.
[0005]
[Problems to be solved by the invention]
However, in the case of an overhead cam (OHC) type engine having a valve chamber in the cylinder head, the cam shaft and the cylinder block are used to rotate the cam shaft of the valve opening / closing mechanism provided in the valve chamber of the cylinder head. The crankshaft located below the crankshaft must be connected by a timing chain or the like to transmit the rotational force of the crankshaft to the camshaft.
[0006]
Therefore, it is necessary to provide a chain housing chamber for accommodating the timing chain at a side position of the cylinder bore. As a result, the chain housing chamber is interposed between the cylinder bore and the outer wall portion of the cylinder block.
[0007]
As a result, in the case of an air-cooled engine, cooling fins cannot be provided in the vicinity of the cylinder bore on the chain housing chamber side, and the cooling capacity of the cylinder bore on the chain housing chamber side tends to be insufficient. As a result, in the peripheral area of the cylinder bore, the chain housing chamber side locally becomes hot, and the temperature distribution in the circumferential direction of the cylinder bore is uneven.
[0008]
Such uneven temperature distribution in the circumferential direction inhibits uniform expansion deformation of the cylinder bore when the cylinder block is thermally expanded, promotes uneven deformation, and has a subtle effect on the clearance with the piston. In the worst case, there is a risk of inducing problems such as a decrease in engine output and an increase in consumption of lubricating oil.
[0009]
The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to improve the cooling capacity of the cylinder bore on the chain housing chamber side and make the temperature distribution in the circumferential direction of the cylinder bore uniform. Is to provide.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, an OHC engine according to claim 1 of the present invention is provided on the side surface of the power transmission means accommodation chamber of the partition wall portion separating the cylinder bore and the power transmission means accommodation chamber, and in the valve operating chamber. An oil flow lower part through which the supplied lubricating oil flows is provided, and cooling fins that protrude to a predetermined height and extend a predetermined length in the flow direction of the lubricating oil are provided at the oil flow lower part.
[0011]
This allows the lubricating oil to absorb more heat from the partition wall and actively cool the partition wall part when the lubricating oil flows down the oil flow lower portion where the cooling fin is provided and the surface area is expanded. Promotes heat dissipation from the wall. As a result, the cooling capacity of the cylinder bore on the power transmission means accommodation chamber side can be improved, and the temperature distribution in the circumferential direction of the cylinder bore can be made uniform.
[0013]
According to a second aspect of the present invention, in the OHC engine according to the first aspect, a plurality of the cooling fins are provided at predetermined intervals in a direction intersecting a flow direction of the lubricating oil. Thereby, the oil flow lower part is divided into a plurality by the cooling fins, and the lubricating oil flows down between the cooling fans. And heat dissipation of a partition wall part is accelerated | stimulated with the lubricating oil which flows down the oil flow lower part over a wide range. Therefore, it is possible to further improve the cooling capacity of the cylinder bore on the power transmission means accommodation chamber side and to make the temperature distribution in the circumferential direction of the cylinder bore uniform.
[0014]
According to a third aspect of the present invention, in the OHC engine according to the first or second aspect, a traveling wind passage hole penetrating the cylinder block is provided at an intermediate position between the cylinder bore and the power transmission means accommodating chamber in the partition wall portion of the cylinder block. Drilled. As a result, traveling wind generated when a vehicle or the like equipped with an OHC engine travels at a predetermined speed is introduced and passed through the traveling wind passage hole, and the partition wall portion is cooled by the traveling wind. Therefore, it is possible to improve the cooling capacity of the cylinder bore on the power transmission means accommodation chamber side, and to make the temperature distribution in the circumferential direction of the cylinder bore uniform.
[0015]
According to a fourth aspect of the present invention, in the OHC engine according to the third aspect, the traveling wind passage hole is provided with a plurality of cooling fins protruding in a predetermined height and extending in the penetrating direction. As a result, the outer surface of the traveling air passage hole is expanded by the cooling fin, more traveling air is brought into contact, and heat dissipation of the partition wall portion is further promoted. Therefore, the cooling capacity of the cylinder bore on the power transmission means accommodation chamber side can be further improved, and the temperature distribution in the circumferential direction of the cylinder bore can be made uniform.
[0016]
According to a fifth aspect of the present invention, in the OHC engine according to the third or fourth aspect, a plurality of the traveling wind passage holes are provided at predetermined intervals in the coaxial direction with the Linder bore. As a result, the traveling air passage hole is passed through the cylinder bore in the same direction, and the entire partition wall is cooled. Alternatively, by providing a plurality, the respective outer surfaces are expanded to bring more traveling wind into contact with each other, thereby further promoting the heat radiation of the partition wall. Therefore, the cooling capacity of the cylinder bore on the power transmission means accommodation chamber side can be further improved, and the temperature distribution in the circumferential direction of the cylinder bore can be made uniform.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic explanatory diagram showing an example of a usage state of the OHC engine in the present embodiment. In the present embodiment, the OHC engine 10 is an air-cooled single-cylinder engine, and is used as a prime mover for a so-called four-wheel buggy as shown in FIG. The vehicle 1 is mounted in a slightly tilted state between the front wheel 2 and the rear wheel 3 of the vehicle 1.
[0018]
The OHC engine 10 includes a cylinder block 20, a cylinder head 11 placed above the cylinder block 20, and a crankcase 12 arranged below. The cylinder head 11 has a valve chamber (not shown) having a valve opening / closing mechanism, and the crankcase 12 is a crank chamber that rotatably supports a crankshaft extending in the left-right direction of the vehicle 1. (Not shown).
[0019]
Further, in the OHC engine 10, a lubricating oil flow path through which lubricating oil circulates is provided in order to perform sliding and cooling inside the engine, and the lubricating oil flow path is cranked from the valve chamber of the cylinder head. A path that flows down to the chamber 12 is provided.
[0020]
In this specification, when the vehicle 1 and the OHC engine 10 mounted on the vehicle 1 are viewed from the front of the vehicle, the right side is referred to as the “right side” of the OHC engine 10, and the left side is referred to as the “left side” of the OHC engine 10. .
[0021]
FIG. 2 is a top explanatory view of the cylinder block 20 in the present embodiment, and FIG. 3 is a front explanatory view shown by a cross section taken along line AA of FIG. The cylinder block 20 is formed of an aluminum alloy material, and as shown in FIG. 2, a cylinder portion 30 penetrating substantially the center with a predetermined diameter, and provided on the left side of the cylinder portion 30 in the same direction as the cylinder portion 30. The chain housing chamber 40 is provided.
[0022]
A plurality of air-cooling cooling fins 22 are provided on the outer wall surface 21 of the cylinder block 20 so as to protrude outward from the outer wall surface by a predetermined height and have a predetermined interval therebetween. The cooling fins 22a and 22b for air cooling provided on the front outer wall surface 21a and the rear outer wall surface 21b of the cylinder block 20 extend in the vertical direction, and are provided on the left outer wall surface 21c and the right outer wall surface 21d of the cylinder block 20. The air-cooling cooling fins 22 c and 22 d thus provided are provided so as to extend in the front-rear direction of the cylinder block 20.
[0023]
As shown in FIG. 3, the cylinder portion 30 is formed by press-fitting a cylinder liner 31 into a through hole formed in the cylinder block 20. The cylinder liner 31 is made of a cast iron material having excellent wear resistance, and is formed in a substantially cylindrical shape having a cylinder bore into which a piston can be reciprocally inserted.
[0024]
The chain housing chamber 40 is provided at the left side position of the cylinder portion 30, the upper part is a valve operating chamber of the cylinder head 11 (see FIG. 1), and the lower part is a crank chamber of the crankcase 12 (see FIG. 1). the communicating, to form a power transmission means accommodating chamber in which the timing chain is moving force transmission means you connecting the crank chamber of the crank shaft and the valve operating chamber of the camshaft (both not shown) are accommodated .
[0025]
A partition wall portion 41 is formed between the chain housing chamber 40 and the cylinder portion 30 to partition the two. The side surface of the chain housing chamber 40 of the partition wall portion 41, that is, the side surface of the chain housing chamber 40 on the cylinder portion 30 side (hereinafter simply referred to as “cylinder portion side wall surface”) 45 flows down from the valve operating chamber by the lubricating oil passage. An oil flow lowering portion 46 through which the lubricating oil has flowed down along the surface thereof is provided.
[0026]
That is, the oil flow lower portion 46 constitutes a part of the lubricating oil flow path in which the lubricating oil flows from the valve operating chamber to the crank chamber, and the lubricating oil flowing from the valve operating chamber is separated from the partition wall of the chain housing chamber 40. It flows out to a position above the portion 41.
[0027]
The oil flow lower portion 46 is formed so that the upper half portion 42 is recessed toward the cylinder portion 30, and the lower half portion 43 is disposed at a position farther from the cylinder portion 30 than the upper half portion 42. The vertical cross-sectional shape of the oil flow lower portion 46 forms a substantially crank shape as shown in FIG.
[0028]
The upper half portion 42 has oil cooling cooling fins 44 protruding at a predetermined height and extending for a predetermined length in a direction in which lubricating oil flows (hereinafter simply referred to as “flowing direction”) at predetermined intervals in the front-rear direction. A plurality of them are provided opposite to each other. The oil cooling cooling fins 44 enlarge the surface area of the upper half portion 42 more greatly.
[0029]
Further, a plurality of traveling air passage holes 50 penetrating the cylinder block 20 in the front-rear direction are provided at an intermediate position between the lower half portion 43 and the cylinder portion 30.
[0030]
As shown in FIG. 2, the side wall surface 52 on the chain housing chamber 40 side of the traveling wind passage hole 50 is formed substantially linearly in the front-rear direction, and the side wall surface 53 on the cylinder portion 30 side is The cross section is formed in a substantially arc shape so as to surround the periphery.
[0031]
Next, a cooling method on the chain housing chamber 40 side of the cylinder block 20 having the above configuration will be described below. The cooling of the cylinder block 20 in the present embodiment is two types, one using traveling wind generated when the vehicle 1 travels and the other using lubricating oil flowing down the engine after lubricating the valve operating chamber. Are used together.
[0032]
First, cooling of the cylinder block 20 using traveling wind will be described. For example, when the vehicle 1 travels at a predetermined speed or more, the front outer wall surface 21a of the cylinder block 20 receives traveling wind generated by traveling. Then, the traveling wind passes through the traveling wind passage hole 50 penetrating the cylinder block 20 in the front-rear direction, and at that time, the partition wall portion 41 is cooled. Further, since the plurality of traveling wind passage holes 50 are provided, the heat radiation effect can be further improved by the enlarged outer surface.
[0033]
Since the side wall surface 53 has a substantially arc shape in cross section, the traveling wind can be received by the entire outer peripheral surface region of the cylinder portion 30 and the cylinder portion 30 can be uniformly cooled.
[0034]
Further, since the side wall surface 53 on the cylinder portion 30 side gradually becomes closer to the side wall surface 54 on the chain housing chamber 40 side as it moves to the center of the cylinder block 20, more running wind passes through the running wind. It can be introduced into the hole 50, and the flow velocity of the traveling wind in the traveling wind passage hole 50 can be increased.
[0035]
Therefore, the cooling capacity of the cylinder part 30 on the side of the chain housing chamber 40 can be improved, and cooling can be performed in the same manner as other parts of the cylinder part 30, so that the temperature distribution in the circumferential direction of the cylinder part 30 is made uniform. can do.
[0036]
Next, cooling of the cylinder block 20 with lubricating oil will be described. In the present embodiment, since the bolt hole 25 for fixing the cylinder head 11 is formed on the upper surface of the cylinder block 20, a through-hole penetrating in the front-rear direction of the cylinder block 20 is provided in the upper half portion 42. I can't. Therefore, cooling of the upper half portion 42 is performed using lubricating oil circulating in the engine.
[0037]
The lubricating oil that has flowed out from the valve operating chamber to the upper position of the partition wall portion 41 by the lubricating oil flow channel flows downward along the oil flow lower portion 46 (arrow B in FIG. 3). It flows down while absorbing the heat of 42.
[0038]
Thereby, the partition wall part 41 can be cooled and the heat dissipation can be promoted, and the cooling capacity of the cylinder part 30 on the side of the chain housing chamber 40 can be improved in combination with the cooling action using the traveling air described above.
[0039]
Therefore, the local high temperature state of the cylinder block 20 resulting from insufficient cooling of the cylinder part 30 on the chain housing chamber 40 side can be prevented. That is, the chain housing chamber 40 side of the cylinder block 20 can be cooled in the same manner as other portions, and the temperature distribution in the circumferential direction of the cylinder portion 30 can be made uniform.
[0040]
Thereby, the cylinder part 30 can be thermally expanded uniformly in the circumferential direction even in a high temperature state, and local deformation of the cylinder part 30 can be suppressed, resulting in a decrease in output and an increase in oil consumption. Etc. can be prevented.
[0041]
In addition, this invention is not limited to the above-mentioned this Embodiment, A various change is possible within the summary of this invention. For example, in the above-described embodiment, a plurality of traveling wind passage holes 50 are provided in the coaxial direction with the cylinder portion 30, but the present invention is not limited to this, and a long hole-like opening shape is provided in the coaxial direction with the cylinder portion 30. Even when a plurality of cooling fins that are provided so as to protrude are provided, the same effect as that of the plurality of traveling wind passage holes 50 can be obtained.
[0042]
【The invention's effect】
As described above, according to the OHC engine according to the present invention, in the process in which the lubricating oil flows down the oil flow lower part, the lubricating oil absorbs the heat of the partition wall part, and the partition wall part is actively cooled, Heat dissipation of the partition wall can be promoted. In addition, the partition wall can be cooled using traveling wind generated when a vehicle or the like equipped with an OHC engine travels at a predetermined speed.
[0043]
As a result, the cooling capacity of the cylinder bore on the chain housing side can be improved, and the temperature distribution in the circumferential direction of the cylinder bore can be made uniform.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram showing an example of a usage state of an OHC engine in the present embodiment.
FIG. 2 is an upper surface explanatory view of a cylinder block in the present embodiment.
FIG. 3 is a front explanatory view shown by a cross section taken along line AA in FIG. 2;
[Explanation of symbols]
10 OHC Engine 20 Cylinder Block 22 Cooling Fin for Air Cooling 30 Cylinder (Cylinder Bore)
40 chain housing chamber (power transmission means accommodation chamber)
41 Partition wall 44 Oil cooling fin 45 Cylinder side wall surface (side surface of power transmission means accommodation chamber)
46 Lower oil flow 50 Running air passage hole

Claims (5)

A cylinder block including a cylinder bore and a power transmission means accommodation chamber that is provided on a side of the cylinder bore and accommodates a power transmission means for transmitting an engine rotational force to a valve opening / closing mechanism in a valve chamber above the cylinder bore;
An oil flow lower portion provided on a side surface of the power transmission means accommodation chamber of a partition wall that partitions the cylinder bore and the power transmission means accommodation chamber, and from which lubricating oil supplied into the valve chamber flows down. In the OHC engine,
An OHC engine characterized in that cooling fins are provided in the lower part of the oil flow that project into the power transmission means accommodation chamber at a predetermined height and extend for a predetermined length in the flow direction of the lubricating oil. The cooling fin is
2. The OHC engine according to claim 1, wherein a plurality of OHC engines are provided at predetermined intervals in a direction intersecting the lubricating oil flow direction. The traveling wind passage hole that penetrates the cylinder block is formed in an intermediate position between the cylinder bore and the power transmission means accommodation chamber in the partition wall portion of the cylinder block. 2. The OHC engine according to 2. 4. The OHC engine according to claim 3, wherein the traveling air passage hole is provided with a plurality of cooling fins that protrude a predetermined height and extend in the penetrating direction. 5. 5. The OHC engine according to claim 3, wherein a plurality of the traveling wind passage holes are provided at predetermined intervals in a direction coaxial with the cylinder bore.

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