Lubrication – Systems – With machine tilt compensating means
Utility Patent
1999-02-03
2001-01-02
Bucci, David A. (Department: 3682)
Lubrication
Systems
With machine tilt compensating means
C184S006500, C184S106000, C123S1960CP
Utility Patent
active
06167990
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an improved lubricating device for four-stroke engines and, more particularly, to a lubricating device which permits the engine to operate in an inverted state for a longer time and which has a much better lubricating effect.
DESCRIPTION OF THE RELATED ART
Engines are frequently used in mowers, sawing machines, pumps and exhaust fans etc. Two stroke engines apt to cause air pollution, are gradually being replaced with engines four-stroke which serve as power sources of the afore-mentioned machines.
A conventional four-stroke engine is usually operated in an upright state. However, for an engine used in a hand-held machine such as a mower, a sawing machine etc, it is sometimes operated in a slightly tilted state or even in a completely inverted state due to functional requirements. In this case, a large quantity liquid of lubricating oil will accumulate on the one side of the piston opposite to the combustion chamber, which not only hinders the displacement of the piston but also leads to a bad lubricating effect.
The construction of a conventional four-stroke engine (in an upright state) will now be illustrated by referring to FIG.
1
. This conventional engine includes a cylinder
20
provided therein with a piston
15
, a connecting rod
21
, and an inlet valve (an exhaust valve)
13
. A rocker chamber Vr is connected to the upper end of the cylinder
20
and is adapted to receive the rockers
12
(only one is shown in
FIG. 1
) adapted to drive the inlet valve (or the exhaust valve)
13
through the swinging motion thereof. A main shaft
1
for transmitting the kinetic energy generated by the engine is rotatably supported by a pair of bearings
4
,
5
mounted in a main shaft chamber Vs. A crank
14
fixed to one end of the main shaft
1
is rotatably connected to the connecting rod
21
. A pair of gears
6
and
7
mounted on the main shaft
1
and another parallel shaft
3
, respectively, engage with each other. A cam
8
is also mounted on the shaft
3
. Consequently, when the cam
8
is driven by the main shaft
1
through the engagement of the gear pair
6
and
7
, it will swing a rocker
9
which, in turn, raise or lower a link
10
and thus swing the rocker
12
having one arm connected to the link
10
. As a result, the rotation of the main shaft
1
causes the opening or closing movement of the inlet valve (or the exhaust valve)
13
. The link
10
is received within a sleeve
11
which communicates the rocker chamber Vr with the main shaft chamber Vs. A lubricating oil reservoir
17
, adapted to receive liquid lubricating oil L therein, is connected to the lower end of the cylinder
20
. A stirrer
16
, attached to the lower portion of the connecting rod
21
, is adapted to splash the liquid lubricating oil L in the lubricating oil reservoir
17
.
Next, the operation (particularly the circulation of lubricating oil) of the above conventional engine will be explained below.
During the operation of the engine, the stirrer
16
keeps on moving up and down following the reciprocal movement of the connecting rod
21
, and splashes the liquid lubricating oil in the lubricating oil reservoir
17
. Some of the splashed lubricating oil enters the main shaft chamber Vs via the clearance and lubricates the parts
3
,
4
,
5
,
6
,
7
,
8
,
9
,
10
of the engine. Some lubricating oil mist further enters the rocker chamber Vr through the clearance between the sleeve
11
and the link
10
, thereby lubricating the rocker
12
and other parts. Since the circulation route taken by the lubricating oil (mist), as explained above, is a single route, lubrication achievable by such a lubricating system is not effective enough.
In the case when the engine is operated in an upright state as shown in
FIG. 1
, most of the liquid lubricating oil is received in the lubricating oil reservoir
17
. However, when the engine is operated upside down as shown in
FIG. 2
, most of the liquid lubricating oil moves to accumulate over the piston
15
and impedes the displacement of the piston
15
. Besides, the stirrer
16
fails to function, leading to a poor lubrication of the engine parts. Thus, the lubrication effect is even poorer than in the case when the lubricating system of the engine is operated in an upright state.
SUMMARY OF THE INVENTION
In order to solve the above problems, this invention therefore provides an improved lubricating device for four-stroke engines which can be operated upside down for a longer period of time and which has a better lubricating effect.
In accordance with the first aspect of the present invention, there is provided an improved lubricating device for a four-stroke engine, the engine including a cylinder provided with inlet valve(s) and exhaust valve(s) therein, rockers for driving the inlet valve(s) and the exhaust valve(s), a rocker chamber connected to the upper end of the cylinder and adapted to receive the rockers, a main shaft for transmitting to outside the kinetic energy generated by the engine, a main shaft chamber communicating with the rocker chamber and adapted to rotatably support the main shaft, and a lubricating oil reservoir having a bottom wall and a side wall and adapted to receive lubricating oil therein. A first partitioning portion divides the lubricating oil reservoir into a first chamber positioned on one side of the first partitioning portion opposite to the bottom wall of the lubricating oil reservoir, and a second chamber located on the other side of the first partitioning portion. The first partitioning portion includes at least one concave portion for receiving the lubricating oil, and at least one opening, provided in the concave portion, which communicates the second chamber with the first chamber.
In addition to the above construction of an improved lubricating device for a four-stroke engine according to the first aspect of this invention, the improved lubricating device according to the second aspect of this invention may further comprise second partitioning portion connecting the side wall of the lubricating oil reservoir and the first partitioning portion so as to further divide the second chamber into a first sub-chamber under the second chamber containing the lubricating oil and a second sub-chamber positioned over the second chamber without lubricating oil therein.
In addition to the above construction of the improved lubricating device for a four-stroke engine according to the second aspect of this invention, the improved lubricating device according to a third aspect of this invention may further comprise check valve provided on the part of the first partitioning portion surrounding the second sub-chamber, which permits the irreversible flow of the lubricating oil mist from the first chamber into the second sub-chamber; a first conduit adapted to communicate the second sub-chamber with the rocker chamber; and a second conduit adapted to communicate the first chamber with the main shaft chamber.
In addition to the above construction of the improved lubricating device for a four-stroke engine according to the second aspect of this invention, the improved lubricating device according to a fourth aspect of this invention may further comprise check valve provided in the part of the first partitioning portion surrounding the second sub-chamber, which permits the irreversible flow of the lubricating oil mist from the first chamber into the second sub-chamber; a first conduit adapted to communicate the second sub-chamber with the rocker chamber; an intake tube which penetrates through and is held by the bottom wall of the lubricating oil reservoir surrounding said first sub-chamber, said intake tube having a first end jutting out of the oil level of lubricating oil when the engine is operated in an upright state and a second end protruding outside of the engine; and a second conduit adapted to communicate said second end of said second intake tube with the main shaft chamber.
REFERENCES:
patent: 821915 (1906-05-01), Altham
patent: 1026287 (1912-05-01), Taylor et al.
patent
Bucci David A.
Industrial Technology Research Institute
Kim Chong H.
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