Splash lubricated over head valve engine

A splash lubricated over head valve engine provided with a gas inducing and a oil return passages both communicate the crank room and the rocker arm chamber, and with a breather disposed inside the rocker arm cover, wherein: the outlet opening of the gas inducing passage and inlet opening of the breather are disposed at opposite end portions of the rocker arm chamber, so as to make the flow of blow-by gas in the rocker arm chamber traverse across the rocker arms aslant.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention is related to a splash lubricated over head valve 
engine which is improved to minimize overall height of the engine and to 
obtain better lubrication of valve driving members such as rocker arms. 
The engine according to the present invention is provided with the premise 
structure; i.e., as shown in the drawings 1 and 2, the splash lubricated 
over head valve engine according to the present invention is provided with 
a gas induction passage 4 and an oil return passage 5 both of which 
communicate a crank room 1 with a rocker arm chamber 3 in a head cover 2 
in parallel. The head cover 2 is provided with a breather 6 which inlet 7 
is communicated with the rocker arm chamber 3. 
2. Description of the Prior Art 
In the splash lubricated over head valve engine of the known type, 
lubricant is fed by means of reciprocation of push rods from the crank 
room to the rocker arm chamber. In this manner, the strength of feeding 
pressure is determined by the stroke of the push rods. Therefore, it is 
impossible to obtain sufficiently high feeding pressure. Moreover, the 
limitation in the location of the opening for spout in the rocker arm 
chamber results in the difficulty of the sure feeding of the lubricant to 
the moving parts of the valve drive mechanism. 
In order to avoid these problems, a breather, which serves to dispose of 
blow-by gas leaked from the combustion chamber to the crankroom, is 
disposed in the space specially provided on the rocker arm chamber so as 
to induce blow-by gas into the rocker arm chamber for the separation of 
the oil therefrom. However, in this known manner, the breather is extruded 
over the head cover, so that the overall height of the engine is tall 
disadvantageously. 
SUMMARY OF THE INVENTION 
The present invention is aimed at dissolving these problems, obtaining 
better lubrication of the parts such as rocker arms still the overall 
height of the engine is kept small. 
In order to attain the objects above mentioned, the present invention, 
shown in FIG. 1-3, is comprised as follows: A rocker arm chamber 3 is set 
on the push rod 8 side of the cylinder head 17 and inclined to the push 
rod 8 side, and a breather 6 is disposed in the upper half end portion of 
the push rod 8 side of the rocker arm chamber 3. 
And an outlet opening 12 of a gas inducing passage 4 is opened at one side 
portion P of the end surface on the inlet and outlet valves 10 and 11 side 
of the rocker arm chamber 3, and an inlet opening 7 of the breather 6 at 
the opposite side portion Q of the end surface on the push rod 8 side of 
the rocker arm chamber 3, so as to make the center line S of the blow-by 
gas flow, which is extended from the outlet opening 12 of the gas inducing 
passage 4 to the inlet opening 7 of the breather 6 through the rocker arm 
chamber 3, tranversing across both rocker arms 14 aslant. 
Therefore, the blow-by gas spouted from the outlet opening 12 of the gas 
inducing passage 4 traverses through the rocker arm chamber 3 aslant, 
separating oils to lubricate both rocker arms 14. 
Then, the separated oils are returned to oil pan 27 through the oil return 
passage 5, and the gas component of the blow-by gas is exhausted from the 
breather 6 after the oils are finely separated in the breather 6. 
Thus, the present invention brings out the following advantages. 
The oil involved in the blow-by gas adheres to the rocker arms and stems of 
the inlet and outlet valves to lubricate them more preferably while it 
traverses across both rocker arms aslant toward the breather. Moreover, 
the length of the flow is elongated so long that a sufficient amount of 
oils adheres for lubrication, since the flow traverses the rocker arm 
chamber aslant. 
As the breather is disposed in the upper half space on the end portion of 
push rod side in the inclined rocker arm chamber, in a sense, it makes a 
dead space, which occupies the slant upper empty portion in the rocker arm 
chamber, useful without extruding in the special space above the chamber. 
Thus, the engine is compact and of a small height. 
The present invention will be more readily understood by reading the 
following detailed description of the preferred embodiments shown in the 
attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In the figures, the engine E acording to a preferred embodiment is provided 
with a crank case 15, a cylinder block 16 made in a body with the crank 
case 15, a cylinder head 17 is fixed on the cylinder block 16, an inlet 
and an outlet valves 10 and 11 both disposed aslant with respect to the 
axis A of the cylinder 18, and rocker arms 14 associated with a cam 20, 
which is disposed in the crank room 1 in the crank case 15, at the power 
intake arm end 19 by means of push rods 8. 
The rocker arm chamber 3 is defined by a head cover 2 fixed on the cylinder 
head 17 to cover the rocker arms 14 from the upper side, and the top 
surface 21 of the cylinder head 17, in the shape inclined lower toward the 
push rod 8 side. 
The cylinder 18 located in the center of the cylinder block 16 contains a 
piston 24 which slides up and down by means of the connection with the 
crank shaft 23 through the connecting rod 22. 
A spoon 26 for splashing the oil is provided at the big end 25 of the 
connecting rod 22, so as to stir the oil reserved in the oil pan 27 
located below the crank case 15 for the realization of the splash 
lubrication of the over head valve engine. 
Besides, a gas inducing passage 4 is passed through in the front side of 
the cylinder block 16, and a passage 5 for push rods 8 passing through the 
left side of the cylinder block 16 is serving as an oil return passage 5 
which communicates the rocker arm chamber 3 and the crank room 1 parallel 
with the gas inducing passage 4. 
The outlet opening 12 of the gas inducing passage 4 is opened at the 
portion P set aside to one of the valves 10 or 11, i.e., at the upper 
portion of the inclined rocker arm chamber 3, while a breather 6 is 
located in the upper half space above the end portion of push rod side of 
the rocker arm chamber 3. 
The breather 6 comprises a partition 28 which closes the upper half space 
above mentioned, and a lead valve 30, and an inlet opening 7 is opened 
through the partition 28 at the side Q which is faced to the push rods 8, 
moreover, the outlet opening 12 of the gas inducing passage 4 directed to 
this inlet opening 7, so as to guide blow-by gas toward the breather 6. 
Therefore, the center line S of blow-by gas is directed aslant with respect 
to a pair of rocker arms 14. 
The lead valve 30 and valve stopper plate 31 are put to capably open and 
shut on the back surface of the partition 28, and the breather chamber 32 
is defined by the head cover 2 and the partition 28. The exhaust port 33 
is provided at the part of side wall of the head cover 2, which part 
defines the breather chamber 32, and conduit pipe 33 is communicated to 
the port 33 for release of blow-by gas into the atom sphere or return of 
it to clean air chamber of an air cleaner 37. 
According to the splash lubricated over head valve engine E mentioned 
above, the oil is fiercely stirred by the spoon 26 connected to the 
connecting rod 22, and misted to fill in the crank case 15, and the 
blow-by gas blown from the combustion chamber to the crank room 1 involves 
the oil mist and rises up to the rocker arm chamber 3 through the gas 
inducing passage 4. 
The blow-by gas raised into the rocker arm chamber 3 traverses from the 
outlet opening 12 of the gas inducing passage 4 toward the inlet opening 7 
of the breather 6 alsant with respect to the rocker arms 14, and during 
the traversing, oil adheres to the parts of valve driving mechanism such 
as rocker arms 14 to lubricate them more preferably. 
Then, the gas component of the blow-by gas introduced into the breather 6 
is selectively exhausted through the conduit pipe 34 after the oil 
involved therein is finely separated by the breather 6. 
In such a manner, the present invention is adopted to the splash lubricated 
over head valve engine to realize more effective and more sufficient 
lubrication of the parts in the head cover.