JPH0723688B2 - Head cooling system for liquid-cooled air-cooled in-line multi-cylinder engine - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cooling device for a cylinder head portion in an in-line multi-cylinder engine.

<< Prior Art >> As a conventional cooling method for a cylinder head of a multi-cylinder engine, either an all-water cooling method or an all-air cooling method is adopted. In the all-water cooling type, a cooling water jacket is formed over the entire area of the head flock, and water is uniformly cooled without distinguishing between the sub-chamber, which is the heat storage section, and the portion other than the heat storage section. In the all-air cooling type, air cooling is uniformly performed without distinguishing between the sub-chamber, which is the heat storage section, and the portion other than the heat storage section.

<< Problems to be Solved >> There are the following problems (i) to (iii) instead of the all liquid cooling type and all air cooling type.

(I) In the all-water cooling type, the sub-chamber, which is the heat storage portion of the head block, and the portion other than the heat storage portion are uniformly water-cooled. For this reason, the amount of heat radiated to the cooling water is large, and it is necessary to use a large amount of cooling water, which increases the weight of the engine. In addition, a radiator such as a radiator that radiates the cooling water also becomes large, and the engine becomes large accordingly.

(Ii) In the case of the all-water cooling type, parts other than the heat storage part, which is relatively difficult to be heated, are supercooled by water cooling. Therefore, a large amount of unnecessary heat is radiated from the main combustion chamber to this supercooled portion, resulting in a large heat loss. On the other hand, in the case of the all air cooling type, the heat storage portion which is relatively overheated is cooled only by air cooling. Therefore, the combustion temperature cannot be set too high because it is necessary to suppress thermal damage due to overheating of the heat storage unit. As described above, the heat loss is large in the all-water cooling type, and the high output cannot be obtained in the all-air cooling type due to the restriction of the combustion temperature.

(Iii) In the case of the all water cooling type, the cooling water outlet is provided only on either the front side or the rear side of the head block. Therefore, while the cooling water that has not been subjected to the heat radiation of the other cylinder parts passes through the counter outlet side cylinder part of the head block farthest from the cooling water outlet, the upstream side of the head block exit side cylinder part After passing through the cooling water that has received the heat radiation of all the cylinder parts on the side, a large difference occurs in the cooling conditions of the cylinder parts. Further, in the case of the all air cooling type, a cooling air intake port is formed on the front side of the head block and a cooling air discharge port is formed on the rear side of the head block. Therefore, while the cooling air immediately after being taken in from the cooling air inlet passes through the front cylinder portion of the head block near the cooling air inlet, the rear side portion of the head block near the cooling air outlet, The heat is radiated from the front cylinder portion, the temperature rises, and the cooling air passes through, causing a large difference in the cooling conditions of the front cylinder portion and the rear cylinder portion of the head block. As described above, in all cases of all water cooling type and all air cooling type, a large difference occurs in the cooling condition of each cylinder portion, which causes a difference in the combustion state of each cylinder,
The output of each cylinder becomes unbalanced and vibration is likely to occur.

Therefore, the present inventor made a tentative plan prior to the present invention as shown in FIG. This forms a cooling liquid chamber (52) around a sub chamber (51) formed on the intake port (50) side of the head block, cools the sub chamber (51) portion with the cooling liquid, and exhaust port (52). A cooling air intake (54) is formed at the outlet end of 53), and a cooling air outlet (55) is formed at the outlet end of the intake port (50) so that the cooling air is directed parallel to the valves. It is designed to flow in the orthogonal direction.

In the preceding trial example, although the above problems (i) to (iii) can be solved, the following new problem (iv) occurs.

(Iv) Since the plurality of cooling liquid chambers (52) are arranged along the cooling air discharge port (55), it is not possible to form the cooling air discharge port (55) in a wide area, and the cooling air passage has high air cooling efficiency. Was difficult to form.

An object of the present invention is to provide a head cooling device for an air-cooled in-line multi-cylinder engine which can be combined with liquid cooling and which can solve the above problems.

<< Means for Solving the Problem >> In the present invention, a plurality of cylinders (8) are arranged in parallel in the front and rear, and intake ports (9) and exhaust ports (10) have outlets (9a) (10a) in each cylinder. The sub-chambers (11) are formed side by side in the left-right direction in the space between the valve openings of each cylinder, and the sub-chambers (11) are placed in the front-rear direction at the left-right lateral side of the head block (3). In the head block (3), the cooling liquid chamber (12) is formed so as to surround the sub chamber (11) and the cooling liquid can be supplied to the cooling liquid chamber (12).
The sub-chamber (11) is partially cooled with the cooling liquid in the cooling liquid chamber (12), and each exhaust port (10) is moved from its valve port (10a) to the side opposite to the cooling liquid chamber (12) in the left-right direction. The cooling air intake (15) is formed on the side surface of the head block (3) on the outlet side of the exhaust port (10), and is cooled from the cooling fan (6) to the cooling air intake (15). It is characterized in that it is configured to be able to supply wind, and cooling air discharge ports (17) are formed on both front and rear side surfaces of the head block (3).

<< Operation >> According to the present invention, in the head block (3), the sub-chamber (11), which is a heat storage part, is partially liquid-cooled by the cooling liquid supplied to the cooling chamber (12), and other than the heat storage part. Is cooled by the cooling air from the cooling fan (6). The cooling air is taken in from the cooling air intake (15) on the lateral side surface of the head block (3), and is discharged from the cooling air discharge ports (17) on the front and rear side surfaces of the head block (3), respectively. The cooling air intake (15) is connected to the cooling liquid chamber (1
In addition to being provided on the opposite side in the left-right direction of 2), the cooling air discharge port (17) is formed on both front and rear surfaces of the head block (3), so that the cooling air intake port (15) and the cooling air discharge port ( A plurality of coolant chambers (12) are not lined up along 17).

<Embodiment> The drawings show an embodiment of the present invention. FIG. 1 is a cross-sectional plan view of a cylinder head of a two-cylinder diesel engine, and FIG.
It is a vertical side view of a cylinder diesel engine.

In this engine, a crankcase (1) and a cylinder block (2) are integrally formed to form a cylinder block (2).
A flywheel that serves as a cooling fan at the front end of the crankshaft (5) protruding from the front wall (4) of the crankcase (1) by fixing the head block (3) to the upper side of the crankcase (1). The fan (6) is fixed, the flywheel fan (6) is surrounded by a wind guide case (7), and the cooling air generated by the flywheel fan (6) is supplied to the cylinder block (2) and the pad block (3). The engine is cooled by sending it to the engine.

As shown in FIG. 1, the head block (3) is formed with an intake port (9) and an exhaust port (10) corresponding to each cylinder (8), and combustion of this intake port (9) The chamber side opening (intake valve opening) (9a) and the combustion chamber side opening (exhaust valve opening) (10a) of the exhaust port (10) are arranged in parallel with the crankshaft (5). The manifold-side end portion (9b) of the intake port (9) is located on one side surface of the head block (3), and the manifold-side end portion (10b) of the exhaust port (10) is located on the head block (3). It has openings on the other side, and it has a cross-flow valve arrangement as a whole. That is, the intake port (9) and the exhaust port (10) are connected to the respective valve openings (9a) (10a).
From the left to the right. Further, the intake ports (9) are led out to the same side, and the exhaust ports (10) are led out to the same side. Valve ports (9a) of both ports (9) (10)
A spherical sub-chamber (11) is provided in the inlet side of the intake ports (9) between (10a). A fuel injection nozzle is arranged to face the sub chamber (11), and a cooling liquid chamber (12) through which a cooling liquid flows is formed around the sub chamber (11). Then, in the cooling liquid chamber (12), a part of the lubricating oil pumped by a lubricating oil pump (not shown) serves as a cooling liquid, and a cooling liquid passage (13) formed in the cylinder (8) and the head block (3). ) Is to be supplied via. The cooling liquid passage (13) is formed so as to pass between the valves in the head block (3). Further, the lubricating oil supplied to the cooling liquid chaver (12) is cooled by the oil cooler arranged in the cooling air passage of the cooling air blown by the flywheel fan (6), and then the crankcase (1) It is designed to be returned to the oil sump (14) formed at the bottom.

The cooling air created by the flywheel fan (6) is guided by the air guide to the side surface of the head block (3) on the exhaust port lead-out side to cool the exhaust port of the head block (3). It is formed on the wind intake (15). And in the head block (3),
The cooling air that has flowed in from the cooling air intake port (15) cools the peripheral wall portion of the exhaust port (10) and is located on the flywheel fan (6) side and on the rear side portion of the crankcase (1). Cooling air outlet formed on the 16) side (17)
From the head block (3). That is, cooling air discharge ports (17) are formed on both front and rear side surfaces of the head block (3).

In the figure, reference numeral (18) is a push rod insertion hole portion, (19) is an intake valve, and (20) is an exhaust valve.

FIG. 3 is a view corresponding to FIG. 1 of another embodiment of the present invention. In this embodiment, by arranging the arrangement states of the intake port (9) and the exhaust port (10) formed corresponding to each cylinder (8) symmetrically in the adjacent cylinders (8),
Combustion chamber side opening (10a) of the exhaust port (10) is located close to each other, and adjacent cylinders (8)
The sub-chamber (11) is surrounded by one cooling liquid chamber (12). This arrangement can be applied to even-cylinder engines such as 4-cylinder engines as well as 2-cylinder engines.

FIG. 4 shows yet another embodiment in which the intake valve openings (9a) and the exhaust valve openings (10a) are located close to each other in the adjacent cylinders, and the exhaust gas is exhausted. Valve (10
a) They are arranged so that they are separated from each other. The intake port (9) led out from each cylinder is merged in the head block (3) and opened to the upper wall of the head block (3). On the other hand, the exhaust port (10) derived from each cylinder is opened on the side surface of the head block (3) through the space between push rods arranged corresponding to each cylinder. Therefore, the push rod insertion hole (18) formed so as to surround the push rod is formed separately on both sides of the exhaust port (10).

Although the engine lubricating oil is used as the cooling liquid supplied to the periphery of the combustion chamber in each of the above-described embodiments, a dedicated cooling liquid (for example, cooling water) may be used.

Further, as shown in the above embodiment, when the cooling liquid passage is formed in the head block so as to pass through the valve-valve portion, the cylinder pitch can be narrowed.

<< Effect >> The present invention has the following effects.

The sub-chamber, which is a heat storage portion of the head block, is partially liquid-cooled, and the portion of the head block other than the heat storage portion is air-cooled.
Therefore, compared to an all-water cooling type in which the heat storage part of the head block and parts other than the heat storage part are all uniformly cooled without distinction, the amount of heat radiated to the cooling liquid is small and the amount of cooling liquid used is small. The engine can be lightened accordingly. Further, a radiator such as an oil cooler or a radiator that radiates the heat of the cooling liquid is also small, and the engine can be downsized accordingly.

The parts other than the heat storage part, which are relatively hard to be overheated, are gently cooled by air cooling, and the supercooling of this part is suppressed. Therefore, unnecessary heat radiation from the main combustion chamber can be suppressed, and heat loss is reduced, as compared with an all-water cooling type in which the parts other than the heat storage part are supercooled by water cooling. On the other hand, the heat storage part, which is relatively easily overheated, is strongly cooled by liquid cooling. For this reason, the combustion temperature can be set higher without fear of thermal damage to the heat storage unit, as compared with the all air cooling type in which the heat storage unit is cooled only slowly. In this way, since the combustion temperature can be set high while reducing the heat loss, a higher output can be obtained as compared with the all-water cooling type or all-air cooling type.

Cooling air is taken in through the cooling air intake on the lateral side of the head block and is emitted from the cooling air outlets on the front and rear sides of the head block respectively, so the cooling conditions for the front cylinder part and the rear cylinder part of the head block Difference is unlikely to occur. Therefore, compared to an all-water cooling type or an air cooling type that causes a large difference in the cooling conditions of each cylinder part, the difference in the combustion state of each cylinder is less likely to occur, the balance of the output of each cylinder is improved, and vibration is generated. Can be suppressed.

The cooling air intake port is provided on the opposite side in the lateral direction of the cooling liquid chamber, and the cooling air discharge port is formed on both front and rear surfaces of the head block. Therefore, a plurality of cooling liquid chambers are not arranged along the cooling air intake port or the cooling air discharge port, and the cooling air passage having high air cooling efficiency can be easily formed.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention, FIG. 1 is a cross-sectional plan view of a cylinder head of a two-cylinder diesel engine, and FIG. 2 is a vertical sectional view of a two-cylinder diesel engine.
FIGS. 3 and 4 are views corresponding to FIG. 1 showing different embodiments, and FIG. 5 is a view corresponding to FIG. 1 of the invention devised prior to the present invention. 1 ... Crank case, 3 ... Head block, 6 ...
Cooling fan (flywheel fan), 8 ... Cylinder, 9 ... Intake port, 9a ... (9) valve port, 10 ... Exhaust port, 10a ... (10) valve port, 11 ... Sub chamber , 12 ……
Coolant chamber, 15 ... Cooling air intake, 17 ... Cooling air outlet.

Claims (1)

[Claims] 1. A plurality of cylinders (8) are arranged side by side in front and rear, and intake ports (9) and exhaust ports (10) of the respective cylinders are arranged side by side in front and back, respectively. A sub-chamber (11) is formed laterally on one side in the left-right direction between the valve openings of the cylinders, and each sub-chamber (11) is arranged side by side on the left-right lateral side of the head block (3). The cooling liquid chamber (12) is formed so as to surround the cooling liquid chamber (12), and the cooling liquid chamber (12) can be supplied with the cooling liquid.
The sub-chamber (11) is partially cooled with the cooling liquid in the cooling liquid chamber (12), and each exhaust port (10) is moved from its valve port (10a) to the side opposite to the cooling liquid chamber (12) in the left-right direction. The cooling air intake (15) is formed on the side surface of the head block (3) on the outlet side of the exhaust port (10), and is cooled from the cooling fan (6) to the cooling air intake (15). A head cooling device for an air-cooled in-line multi-cylinder engine for liquid cooling, which is configured to be able to supply air and has cooling air discharge ports (17) formed on the front and rear side surfaces of the head block (3).