JP2626972B2 - Partial liquid cooling system for overhead valve type forced air cooling engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a partial liquid cooling system for an overhead valve type forced air cooling engine, and more particularly, to a head block and a cylinder block for preventing thermal distortion, and for improving performance and durability due to such thermal distortion. It relates to a device capable of preventing a decrease.

[0002]

2. Description of the Related Art Conventionally, as a relatively inexpensive forced air-cooled engine, a side valve type engine which can make the shape of a cylinder head relatively simple has predominantly used. Many engines have come to be seen.

[0003] Generally, in an overhead valve type forced air cooling engine,
An intake valve seat, an exhaust valve seat, an intake port, an exhaust port, and the like are formed in the cylinder head, and the shape of the cylinder head is more complicated than that of the side valve type engine. In addition, in order to reduce the price of many of such overhead valve type forced air cooling engines, and to reduce the overall height of the engine, a valve operating cam is disposed in a crankcase, and a tappet and a tappet disposed on the side of the cylinder are provided. The intake valve and the exhaust valve are driven to open via a push rod and a rocker arm pivotally supported by the head block. In this case, in order to reduce the size of the engine, a push rod chamber is formed on one side of the cylinder with a partition wall interposed therebetween, through which the push rod is inserted. Cooling air is applied to the outer surface of the wall of the push rod chamber on the side opposite to the cylinder. Is typically configured to contact

[0004]

As described above, in an overhead valve type forced air cooling engine having a complicated cylinder head shape, it is difficult to supply cooling air uniformly, and the temperature distribution of the head block becomes uneven. As a result, thermal distortion occurs in the head block, and there is a possibility that the performance and durability of the engine may be reduced by such thermal distortion. In addition, the partition that separates the cylinder and the push rod chamber is directly exposed to the high temperature inside the cylinder, and is isolated from the cooling air by the push rod chamber. Cooling by the wind is not obtained, the temperature rises, the heat distribution in the circumferential direction of the cylinder becomes uneven, and thermal distortion occurs in the cylinder block. The thermal strain of the cylinder block may reduce the performance and durability of the engine similarly to the thermal strain of the head block.

As a prior art for making the heat distribution of the head block of an air-cooled engine uniform, for example, Japanese Unexamined Patent Publication No.
As disclosed in JP-A-81113, a cooling liquid jacket is formed in a head block, and lubricating oil is circulated in the jacket by a cooling lubricating oil pump to make the temperature distribution of the head block uniform. I have. In such a partially oil-cooled air-cooled engine in which the coolant jacket is formed in the head block, it is possible to eliminate the adverse effect on the performance and durability due to the heat distortion of the head block, but the heat distribution of the cylinder block is not improved. Thermal distortion of the cylinder due to uniformity cannot be prevented.

On the other hand, as a prior art for making the heat distribution of the cylinder block uniform, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Application Publication No. 21, it is known that a high-temperature portion of a cylinder block is partially cooled by lubricating oil flowing naturally. Utilizing this conventional technique, the push rod chamber is arranged below the horizontal cylinder, and the oil pan formed at the bottom of the crank room and the push rod chamber are communicated to form a partition between the cylinder and the push rod chamber. It is possible to cool. However, in this case, the push rod passes under the cylinder, and the intake port and the exhaust port are arranged horizontally in the center of the cylinder so as to obtain the largest possible opening area. The support shaft is arranged in the lower half of the head block, and the sub-chamber, the intake port, the exhaust port and the like are usually arranged above the center of the cylinder head. On the other hand, since the lubricating oil level of the oil pan is generally set lower than the lower peripheral edge of the cylinder, the high-temperature portion of the head block cannot be cooled by the lubricating oil flowing naturally. In tilted cylinder engines and vertical engines where the cylinders are not horizontal, not only the hot parts of the head block,
The partition between the cylinder and the push rod chamber cannot be cooled.

For example, as disclosed in Japanese Patent Application Laid-Open No. 54-16040, the head block and the cylinder block are entirely cooled with lubricating oil to make the heat distribution of the head block and the cylinder block uniform. However, such an all-oil-cooled engine requires a considerably large amount of lubricating oil, and is disadvantageous in reducing the size and weight. This point is described, for example, in JP-A-59-58.
As shown in Japanese Patent Publication No. 26, even when the entire cylinder block is oil-cooled with lubricating oil and the head block is water-cooled, the total amount of cooling liquid, which is the sum of cooling lubricating oil and cooling water, increases. It is.

The present invention has been made in view of the above-mentioned circumstances, and an overhead valve configured to prevent generation of thermal distortion of a head block and a cylinder block using a relatively small amount of coolant. It is an object of the present invention to provide a partial liquid cooling device for a forced air cooling engine.

[0009]

In order to solve the above-mentioned problems, the present invention is characterized in that it is configured as follows, for example, as shown in FIGS. That is, a coolant head jacket is provided around at least a relatively high temperature portion (28) of the head block (3) of the overhead valve type forced air cooling engine.
(33), a partition wall (16) for partitioning the cylinder (24) of the cylinder block (2) joined to the lower surface of the head block (3) and the push rod chamber (18). 17) and form a circulation path for circulating the cooling liquid from the cooling liquid side jacket (17) to the cooling liquid side jacket (17) again through the cooling liquid head jacket (33). And a cooling means (12, 35) for cooling the coolant in the circulation path between the coolant head jacket (33) and the coolant side jacket (17).

[0010] The high temperature portion of the head block is a portion at which the temperature becomes higher than that of the cylinder block. Other than this, for example, a wall that is difficult to reach because cooling air is obstructed by other members, such as a wall between an intake port and an exhaust port, and that is easily heated and cooled. In other words, it includes all parts that are higher in temperature than other parts, such as difficult parts, only by forced air cooling.

As the coolant, lubricating oil distributed from the lubrication system of the engine can be used, and oil, water, and the like circulated independently from the lubrication system of the engine can be used.
Ethylene glycol aqueous solution (antifreeze) or other heat medium can be used. Further, the circulation of the cooling liquid may utilize natural convection, or may be forcedly circulated using a pump. As a cooling means, a heat exchanger such as a radiator or an oil cooler may be used.For example, heat is naturally diffused by a large amount of coolant such as an oil pan to dissipate heat. What causes them to be used may be used.

[0012]

According to the partial liquid cooling device of the overhead valve type forced air cooling engine configured as described above, the cylinder (24) and the push rod chamber (18) are formed while the coolant passes through the coolant side jacket (17). Is cooled, and then the high-temperature portion (28) of the head block (3), which is guided to the coolant head jacket (33) and has a higher temperature, is cooled. At this time,
The temperature of the coolant rises due to heat exchange when passing through the coolant side jacket (17). However, since the high temperature part (28) of the head block (3) is higher in temperature, this high temperature part (28) Is sufficiently cooled by the heated coolant, and the head block
(3) The occurrence of thermal distortion is prevented.

The coolant that has passed through the coolant head jacket (33) and has become even hotter is cooled by the cooling means (12 and 35), and then circulated again to the coolant side jacket (17). For this reason, the cooling liquid guided to the cooling liquid side jacket (17) is always at a low temperature, and the cylinder block (2)
The partition (16) is sufficiently cooled, the temperature distribution on the peripheral wall of the cylinder (24) is made uniform, and the occurrence of thermal distortion is prevented.

Further, the cooling of the engine is not entirely liquid-cooled, but is basically performed by forced air cooling. In particular, only the high-temperature part which cannot be sufficiently cooled by forced air cooling is liquid-cooled. I'm done.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical rear view of a head block and a cylinder block of a vertical overhead valve forced air-cooled sub-chamber diesel engine to which an embodiment of the present invention is applied, FIG. 2 is a rear view of the engine, and FIG. AA of 1
FIG. 4 is a plan view of the cylinder block,
FIG. 5 is a vertical sectional side view of the engine.

This vertical overhead valve forced air-cooled subchamber diesel engine comprises an aluminum alloy integrally cast crankcase (1) and a cylinder block (2), and an aluminum alloy head block (3) on the upper side thereof. Are combined. A crankshaft (4), a balancer shaft (5), and a valve gear camshaft (6) are pivotally supported in the crankcase (1). The front end (4a) of the crankshaft (4) is a crankcase
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 a wind guide case (8),
The air taken in by the cooling fan (7) from the air inlet (9) formed in the front part of the wind guide case (8) is used as cooling air as a wind guide case.
It is guided to (8) and supplied to the cylinder block (2) and the head block (3) of the engine.

A trochoidal lubricating oil pump (10) is incorporated in the rear wall (1a) of the crankcase 1. This lubricating oil pump (10) is connected to a crankshaft (4) via a gear device (11).
The lubricating oil is pumped via an oil strainer (13) from an oil pan (12) formed at the bottom of the crankcase (1), and a lubricating oil supply passage formed inside the crankshaft (4) It is configured to supply lubricating oil to each part of the engine via (14).

A cooling oil forward path (15) branches off in the middle of the lubricating oil supply path (14), and the cooling oil forward path (15) passes through the inside of the rear wall (1a) of the crankcase (1) and passes through the cylinder block. It is led to the lower part on one side of (2). A push rod chamber (18) extending vertically extends inside the wall on one side of the cylinder block (2).
A push rod chamber (18) and a cylinder (24) are formed.
A liquid coolant side jacket (17) is formed inside a partition (16) that separates the coolant and extends vertically and is opened at the upper end surface of the cylinder block (2). The lower part of this coolant side jacket (17) is through the relief valve (19)
(15). The width of the cooling oil side jacket (17) in the circumferential direction of the cylinder (24) is formed to be slightly smaller than that of the push rod chamber (18).

The push rod chamber (18) has a valve operating camshaft.
A pair of tappets (21) that move up and down according to the cam (20) of (6)
A push rod (22) which is in contact with the upper part of the tappet and the upper end of each tappet (21) and moves up and down following each tappet (21) is inserted. An oil return hole (23) communicating with the crankcase (1) is formed in the bottom wall of the push rod chamber (18).
The front side of the cylinder block (2) is provided with an oil return hole and a breather passage (27) communicating the crank room (39) in the crank case (1) with the rocker arm chamber (26) in the head cover (25). ) Is formed.

The head block (3) fixed above the cylinder block (2) includes a sub chamber (28), an intake valve seat (29), an exhaust valve seat (30), an intake port (31) and an exhaust port. (32) is formed. The sub-chamber (28) is eccentric to the right (left in FIG. 1, downward in FIG. 3) with respect to the center of the cylinder (24), and slightly behind (center in FIG. 3) with respect to the center of the cylinder (24). (In the left side), the intake valve seat (29) and the exhaust valve seat (30) are arranged side by side on the left-right center line of the cylinder (24). The intake port (31) extends from the intake valve seat (29) to the sub-chamber (2
The exhaust port (32) extends rearward from the exhaust valve seat (30) to the right side of the head block (3) across the front of (8).

Around the sub-chamber (28) of the head block (3), the start end of the exhaust port (32) and the intake port (3)
1) Coolant head jacket over the range up to the peripheral wall
(33) is formed. The cooling liquid head jacket (33) is opened to face the cooling liquid side jacket (17), and a cooling oil introduction path (34) passing through a wall portion between the intake port (31) and the exhaust port (32). The oil cooler (35) is connected to the coolant side jacket (17) through the
Is connected to a cooling oil outlet passage (36) which is open to face the push rod chamber (18). This oil cooler (3
5) is supplied from a cooling fan (7) as required, and is cooled by a part of the cooling air guided by a baffle case (8).

When the total amount of the lubricating oil is sufficiently large and the heated lubricating oil is quickly mixed with another lubricating oil in the oil pan (12) and cooled sufficiently, the heat generated by the lubricating oil is Since the deterioration can be prevented for a sufficiently long period, the oil cooler (35) can be omitted. Also, the relatively low temperature portion of the head block (3), namely, the front wall of the intake port (31), which is in good contact with the cooling air in the cooling air passage (37), the peripheral wall of the exhaust port (32), and the main combustion The upper wall of the room (38) is a cooling fan
It is forcibly air-cooled by cooling air supplied from (7) and guided by a baffle case (8).

In the above configuration, the head block (3)
And the cooling fan as a whole of the cylinder block (2)
(7), and is forcibly air-cooled by the cooling air guided by the baffle case (8). On the partition (16) side, the inner peripheral surface of the cylinder (24) and the cylinder block
(2) The distance from the outer surface is large, and heat is easily stored to form a thick portion. This partition (16) is a push rod chamber.
Since it is isolated from the cooling air path by (18), it is not cooled by the cooling air. Therefore, the partition wall (16) essentially constitutes a high-temperature portion in a cooling method using only forced air cooling, and the circumferential temperature distribution of the cylinder (24) becomes non-uniform.

However, the partition wall (16),
Is prevented by cooling with lubricating oil.
That is, the lubricating oil in the oil pan (12) is
After being filtered in 3), it is supplied to each part of the engine via a lubricating oil supply path (14) by a lubricating oil pump (10), and on the other hand, through a cooling oil forward path (15) to a partition (16). The cooling liquid is guided to the side jacket (17) formed in the cooling liquid. Then, while passing through the coolant side jacket (17), the heat storage of the partition wall (16) is taken to cool it. In this way, the heat stored in the partition (16) is absorbed and removed by the lubricating oil, so that the partition (16) is prevented from becoming hot, and the circumferential temperature distribution of the cylinder (24) is uniformly maintained. . Thus, the occurrence of thermal distortion of the cylinder block (2) is prevented, and the cylinder block (2)
Of the output and durability due to the thermal distortion of the substrate.

Further, the lubricating oil guided from the coolant side jacket (17) to the coolant head jacket (33) via the coolant oil introduction path (34) is supplied to the coolant introduction path (34) and the coolant head jacket (33). 33) While passing through the intake port (31) and the exhaust port
(32) absorbs heat from the wall and the peripheral wall of the sub chamber (28) to prevent the temperature of these parts from rising, while the intake port (31)
Cools the intake air through the peripheral wall of. Thereby, the heat distribution of the head block (3) is made uniform and the head block (3)
This prevents the occurrence of thermal distortion and the reduction in output and durability due to the thermal distortion of the head block (3), while improving the intake charging efficiency.

In the above embodiment, the lubricating oil of the engine is used as the cooling fluid, and the cooling fluid is forcibly circulated by the lubricating oil pump (10) for sending the lubricating oil to each part of the engine. 1) Form a cooling oil forward path (15), and a cylinder block (2) with a coolant side jacket
(17), and only the coolant head jacket (33), cooling oil introduction path (34) and cooling oil outlet path (36) need to be formed in the head block (3). Even if the valve (19) and the oil cooler (35) are included, the configuration is simple and can be implemented at low cost.

The head block (3) is replaced with a head block which can be cooled without heat distortion by only forced air cooling, for example, like a head block of a direct injection diesel engine, and a small amount of cooling is performed. It is also possible to employ a configuration in which the liquid prevents thermal strain only in the cylinder block (2). In this case, the head block is not provided with a coolant head jacket, a cooling oil introduction passage and a cooling oil outlet passage. A recess for communicating the jacket (17) with the push rod chamber (18) may be formed, or a head block and a cylinder block (2) may be formed.
A cutout may be formed in a part of the gasket inserted between the gasket and the gasket to connect the coolant side jacket (17) and the push rod chamber (18). In this way, by simply changing the head block, a plurality of types of engines having different cooling systems can be configured, and parts other than the head block can be used in common to reduce costs.

In the above-described embodiment, the lubricating oil is forcibly circulated, but it is theoretically possible to circulate the lubricating oil by utilizing its natural convection force. The coolant is not limited to the lubricating oil distributed from the lubrication system of the engine, but may be composed of oil, water, or another heat medium such as an ethylene glycol aqueous solution circulating independently of the lubrication system. Is also good.

[0029]

As described above, according to the partial liquid cooling system of the overhead valve type forced air cooling engine of the present invention, the partition wall between the cylinder and the push rod chamber, which is the high temperature portion of the cylinder block, and the high temperature portion of the head block. Is cooled strongly with a cooling liquid, so that the heat distribution of the head block and the cylinder block can be made uniform to prevent the occurrence of thermal distortion, and to prevent the output and durability from being reduced due to such thermal distortion.

Furthermore, since most of the engine is cooled by forced air cooling and liquid cooling is partial, the amount of cooling liquid can be made relatively small, which is advantageous in reducing the size and weight of the engine. In addition, since the partition wall of the cylinder block is cooled by the cooling liquid having a low temperature by the cooling means, and the high temperature part of the higher temperature head block is cooled by the cooling liquid, both the cylinder block and the head block can be efficiently cooled. Cooling can make the heat distribution uniform.

[Brief description of the drawings]

FIG. 1 is a vertical rear view of a head block and a cylinder block of a vertical overhead valve forced air-cooled sub-chamber diesel engine to which an embodiment of the present invention is applied.

FIG. 2 is a rear view of the engine.

FIG. 3 is a plan view taken along line AA of FIG. 1;

FIG. 4 is a plan view of a cylinder block of the engine.

FIG. 5 is a vertical sectional side view of the engine.

[Explanation of symbols]

 2: Cylinder block, 3: Head block, 12: Cooling means (oil pan), 16: Partition wall, 17: Coolant side jacket, 18: Push rod chamber, 24: Cylinder, 28: High temperature part of the head block, 33: Coolant head jacket, 35 ... cooling means (oil cooler).

Claims (1)

(57) [Claims] 1. A cooling liquid head jacket (33) is formed at least around a high temperature portion (28) of a head block (3) of an overhead valve type forced air cooling engine where a temperature is relatively high. A coolant side jacket (17) is formed on a partition (16) that partitions the cylinder (24) of the cylinder block (2) and the push rod chamber (18) joined to the lower surface. Through the coolant head jacket (33) again to the coolant side jacket (17),
A circulation path for circulating the coolant is formed, and a coolant head jacket (3
A partial liquid cooling device for an overhead valve type forced air cooling engine, comprising cooling means (12, 35) for cooling the cooling liquid between 3) and the cooling liquid side jacket (17).