JPH094430A - Lubricating device for overhead valve engine - Google Patents

Abstract

PURPOSE: To suppress vaporization of lubricating oil and reduce the consumption rate of lubricating oil in a lubricating device in which the lubricating oil over a cylinder head flows down through a push rod insertion hole by covering a surface of an exhaust port wall with a heat insulative cover, and making the lubricating oil flow along the surface of the heat insulative cover. CONSTITUTION: An exhaust port wall 3a of a cylinder head 1 is arranged adjacent to a push rod insertion hole 5. Lubricating oil over a cylinder head 1 is flowed down through the push rod insertion hole 5 which is communicated with a space inside a crank case sequentially through a flow-down hole of a tappet, a cam chamber and an oil guide passage. The flowed lubricating oil returns to an oil pan. In such a case, an air layer 6 remains with respect to the exhaust port wall 3 which is covered with a heat insulative cover 7. The lubricating oil flowing down inside the push rod insertion hole 5 also flows along the surface of the heat insulative cover 7. Vaporization of the lubricating oil is thus suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating device for an overhead valve engine, and more particularly to a device capable of suppressing thermal deterioration of lubricating oil.

[0002]

2. Description of the Related Art As a prior art of a lubrication device for an overhead valve engine, there is one shown in FIG. This is similar to the present invention.
It has the following basic structure. That is, the exhaust port wall 103 of the cylinder head 101 and the push rod insertion hole 1
No. 05 and No. 05 are arranged next to each other so that the lubricating oil on the cylinder head 101 flows down through the push rod insertion hole 105.

In this conventional technique, the surface of the exhaust port wall 103 is exposed in the push rod insertion hole 105, and the lubricating oil flowing down in the push rod insertion hole 105 comes into contact with the exhaust port wall 103.

[0004]

The above-mentioned conventional techniques have the following problems. Since the surface of the exhaust port wall 103 is heated to a considerably high temperature due to exhaust heat, the lubricating oil in contact with the surface thereof is rapidly deteriorated by heat, and the useful life of the lubricating oil is shortened.

Lubricating oil that comes into contact with the surface of the exhaust port wall 103 at high temperature is likely to evaporate, and the vapor is discharged from the breather chamber, so that the lubricating oil is consumed in a large amount.

In order to prevent the above problem, it is conceivable to cover the entire circumference of the exhaust port wall 103 with a liquid cooling jacket 113, but in this case, the cylinder head 101.
Structure becomes complicated, and its manufacturing cost increases.

An object of the present invention is to provide a lubricating device for an overhead valve engine which can suppress thermal deterioration of lubricating oil.

[0008]

According to the present invention, as shown in FIG. 1 (or FIG. 2 or FIG. 3), the exhaust port wall 3 of the cylinder head 1 and the push rod insertion hole 5 are arranged next to each other, and A lubricating device for an overhead valve engine in which the lubricating oil on the head 1 flows down through the push rod insertion hole 5 is characterized by the following.

That is, the surface of the exhaust port wall 3 is covered with a heat shield cover 7, an air layer 6 is provided between the surface of the exhaust port wall 3 and the heat shield cover 7, and lubricating oil flowing down in the push rod insertion hole 5 is provided. However, it is characterized in that it flows over the surface of the heat shield cover 7.

[0010]

According to the present invention, the following effects can be obtained.
(See FIG. 1, FIG. 2 or FIG. 3). The heat insulation effect of the air layer 6 suppresses the transfer of exhaust heat from the surface of the exhaust port wall 3 to the heat shield cover 7. Therefore, the surface temperature of the heat shield cover 7 is considerably lower than the surface temperature of the exhaust port wall 3. Become. Therefore, thermal deterioration of the lubricating oil that comes into contact with the surface of the heat shield cover 7 is suppressed, and the useful life of the lubricating oil can be extended.

Since the temperature of the surface of the heat shield cover 7 is considerably lower than that of the surface of the exhaust port wall 3, the lubricating oil that comes into contact with the surface of the heat shield cover 7 is hard to evaporate, and the consumption amount of the lubricating oil can be reduced.

A simple structure for covering the surface of the exhaust port wall 3 with a heat shield cover 7 is not required, and there is no need to adopt a structure for covering the entire circumference of the intake port wall 3 with a liquid cooling jacket, and the structure of the cylinder head 1 is simple. It can be left untouched and there is no risk of increasing its manufacturing costs.

[0013]

1 and 4 are views for explaining a first embodiment of the present invention. In this embodiment, a multi-cylinder vertical overhead valve engine is used. The structure of this engine is as follows. That is, as shown in FIG. 4, the cylinder head 1 and the head cover 14 are assembled in order above the cylinder block 11, and the intake port 15 and the exhaust port 2 are formed in the cylinder head 1 in directions opposite to each other. A valve operating device 17 such as a rocker arm shaft 16 and a rocker arm 21 is mounted on the top, and the head cover 14 covers the valve operating device 17. A valve operating cam shaft 18 is arranged in the cam chamber 19 of the cylinder block 11 so as to be long in the front-rear direction.
The intake / exhaust valve 23 is interlocked via 1.

This embodiment is equipped with a lubrication device, and its construction is as follows. That is, the cylinder block 1
An oil pan 4 is provided in the lower part of 1, the suction oil passage 25a of the lubrication pump 24 is communicated with an oil strainer 26 in the oil pan 4, and the discharge oil passage 25b of the lubrication pump 24 is connected via an oil filter 27 to the rocker arm shaft 16 , The crankshaft 12, the valve operating camshaft 18, etc.
Then, the lubricating oil in the oil pan 4 is pressure-fed from the oil strainer 26 to each lubricating portion such as the rocker arm shaft 16 by the lubrication pump 24 to forcibly lubricate these portions.

As shown in FIG. 1, the exhaust port wall 3 of the cylinder head 1 and the push rod insertion hole 5 are arranged next to each other, and the lubricating oil on the cylinder head 1 passes through the inside of the push rod insertion hole 5. It's designed to run down. The push rod insertion hole 5 communicates with the crankcase 28 through the downflow hole (not shown) of the tappet 20, the cam chamber 19 and the oil guide path 10 in this order, and the lubricating oil flowing down through the push rod insertion hole 5 Returns into the oil pan 4 below the crankcase 28.

In this embodiment, in order to suppress the thermal deterioration of the lubricating oil, the air layer 6 is left between the exhaust port wall 3 and the exhaust port wall 3 is covered with a heat shield cover 7, and the push rod insertion hole 5 is provided. The lubricating oil flowing down inside is made to flow on the surface of the heat shield cover 7.

According to this structure, heat transfer from the exhaust port wall 3 to the heat shield cover 7 is suppressed by the heat insulation effect of the air layer 6, so that the surface temperature of the heat shield cover 7 is equal to the surface temperature of the exhaust port wall. It is considerably lower than the surface temperature of No. 3. Therefore, thermal deterioration of the lubricating oil that comes into contact with the surface of the heat shield cover 7 is suppressed, and the useful life of the lubricating oil can be extended. Further, since the temperature of the surface of the heat shield cover 7 is considerably lower than that of the surface of the exhaust port wall 3, the lubricating oil that comes into contact with the surface of the heat shield cover 7 is hard to evaporate, and the consumption amount of the lubricating oil can be reduced. Furthermore, a simple structure for covering the exhaust port wall 3 with the heat shield cover 7 is sufficient, and there is no need to adopt a structure for covering the entire circumference of the intake port wall 3 with a liquid cooling jacket, and the structure of the cylinder head 1 can be kept simple. Can be kept, and there is no fear of increasing the manufacturing cost.

The upper and lower parts of the exhaust port wall 3 are covered with a liquid cooling jacket 13, and the front and rear parts are both exposed to the push rod insertion hole 5. As shown in FIG. 2, the heat shield cover 7
Is composed of a downwardly expanding U-shaped elastic plate. As shown in FIG. 1, a seating surface 29 is formed on the upper wall of the liquid cooling jacket 13 that covers the exhaust port wall 3 from above and below, and spacer protrusions 8 are provided on the front and rear portions of the exhaust port wall 3 so as to be vertically separated. Locking protrusions 9 are provided on the front and rear portions of the inner peripheral surface of the push rod insertion hole 5.

The method of attaching the heat shield cover 7 is as follows. That is, as shown in FIG. 1C, the heat shield cover 7 in the expanded posture P indicated by the solid line is narrowed down with a finger or a tool,
It is elastically deformed to a narrowing posture Q shown by a chain line, and while maintaining this narrowing posture Q, the exhaust port wall 3 is covered from above and the side plate 7a of the heat shield cover 7 is covered with the spacer protrusion 8 and the locking protrusion 9. When the top plate 7b of the heat shield cover 7 is seated on the seating surface 29 and the finger or tool is released, the side plate 7a of the heat shield cover 7 expands due to the elastic restoring force, and the locking projection 9 It is received and fixed by friction. The air layer 6 is held between the heat shield cover 7 and the front and rear portions of the exhaust port wall 3.

The second embodiment shown in FIG. 2 is a modification of the first embodiment. As shown in FIG. 2 (C), the heat shield cover 7 is formed in a downward narrowing shape, and the lower ends of both side plates 7a are formed. Spacer claws 7c are formed by bending inwardly at the portions. Other configurations are the same as those of the first embodiment, and in FIG. 2, the same elements as those of the first embodiment are designated by the same reference numerals. A narrow portion 31 is provided on the lower wall 30 of the liquid cooling jacket 13 that covers the exhaust port wall 3 from above and below.

The method of attaching the heat shield cover 7 is as follows. That is, as shown in FIG. 2 (C), the heat shield cover 7 in the narrowed posture Q shown by the solid line is expanded with a finger or a tool, and elastically deformed to the expanded posture P shown by the chain line. While maintaining, cover the exhaust port wall 3 from above and cover the top plate 7b of the heat shield cover 7 with the seating surface 29.
When it is seated on and the finger or the tool is released, the side plate 7a of the heat shield cover 7 is narrowed down by the elastic restoring force, enters the narrowed portion 31, and is locked to the lower wall 30 of the liquid cooling jacket 13.
An air layer 6 is held between the side plate 7a of the heat shield cover 7 and the front and rear portions of the exhaust port wall 3. In the second embodiment, the structure of the cylinder head 1 is simplified because the spacer projections 8 and the locking projections 9 as in the first embodiment are unnecessary.

The third embodiment shown in FIG. 3 is a modification of the first embodiment, in which the heat shield cover 7 is provided with a pair of L-shaped divided pieces 32.
33, and this is fixed to the seating surface 29 with bolts 34. Other configurations are the same as those of the first embodiment, and in FIG. 3, the same elements as those of the first embodiment are designated by the same reference numerals. To mount the heat shield cover 7, the top plates 32b and 33b of the L-shaped split pieces 32 and 33 are placed on the seating surface 29 so as to be seated, and the top plates 32b and 33b are fastened to the seating surface 29 together with the bolts 34. The air layer 6 is held between the side plate 32a of the L-shaped split piece 32 and the front and rear portions of the exhaust port wall 33. In this embodiment, by making the exhaust port wall 6 and the wall of the liquid cooling jacket 13 symmetrical in the front-rear direction, the L-shaped divided pieces 32 and 33 can be used in both the front and rear sides to prevent a mistake in mounting. I can do it.

[Brief description of drawings]

FIG. 1 is a view for explaining a main part of an engine according to a first embodiment, FIG. 1 (A) is a cross-sectional plan view of a cylinder head, FIG.
1B is a vertical side view of the cylinder head, and FIG. 1C is a side view of the heat shield cover.

2A and 2B are diagrams illustrating a main part of an engine according to a second embodiment, FIG. 2A is a view corresponding to FIG. 1A, and FIG.
FIG. 2B is a view corresponding to FIG. 2C, and FIG. 2C is a view corresponding to FIG.

FIG. 3 is a view corresponding to FIG. 1 (B) of an engine according to a third embodiment.

FIG. 4 is a vertical sectional front view of the engine according to the first embodiment.

5A and 5B are diagrams illustrating a main part of an engine according to a conventional technique, FIG. 5A is a view corresponding to FIG. 1A, and FIG.
(B) It is an equivalent figure.

[Explanation of Codes] 1 ... Cylinder head, 3 ... Exhaust port wall, 5 ... Push rod insertion hole, 6 ... Air layer, 7 ... Heat shield cover

Claims (1)

[Claims] 1. An exhaust port wall (3) of a cylinder head (1)
The push rod insertion hole (5) and the push rod insertion hole (5) are arranged next to each other, and the lubricating oil on the cylinder head (1) is
(5) In a lubricating device for an overhead valve engine, which is designed to flow down through the inside, cover the surface of the exhaust port wall (3) with a heat shield cover (7),
An air layer (6) is provided between the surface of the exhaust port wall (3) and the heat shield cover (7), and the lubricating oil that flows down in the push rod insertion hole (5) cleans the surface of the heat shield cover (7). A lubricating device for an overhead valve engine, characterized by being made to flow.