Information
-
Patent Grant
-
6289856
-
Patent Number
6,289,856
-
Date Filed
Friday, December 10, 199925 years ago
-
Date Issued
Tuesday, September 18, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Kamen; Noah P.
- Huynh; Hai
Agents
- Sidley Austin Brown & Wood
-
CPC
-
US Classifications
Field of Search
US
- 123 73 C
- 123 73 PP
- 123 65 W
- 123 65 WA
- 123 1934
- 123 73 A
- 123 1936
-
International Classifications
-
Abstract
A stratified scavenging two-cycle engine is capable of doing away with emission of a mixture into the atmosphere and of reducing intake resistance of air. For this purpose, an air intake port (11) is provided at a position which is a predetermined distance away from scavenging ports (51) toward a crank chamber (20) parallel to the axial direction of the cylinder block (1), and the scavenging ports (51) are connected to the air intake port (11) through a piston (3) to thereby supply air to scavenging flow passages (50) from the air intake port (11) through the scavenging ports (51) at the time of an intake stroke.
Description
TECHNICAL FIELD
The present invention relates to a stratified scavenging two-cycle engine, and particularly relates to a stratified scavenging two-cycle engine which is configured to take in a mixture and scavenging air separately.
BACKGROUND ART
This type of stratified scavenging two-cycle engine conventionally has a scavenging flow passage for connecting a cylinder chamber to a crank chamber; with a mixture flow passage, for supplying a fuel mixture, being connected to the crank chamber; and with an air flow passage, for supplying air, being connected to the scavenging flow passage. A scavenging port of the scavenging flow passage, and an exhaust port of an exhaust pipe are opened to the cylinder chamber. The aforesaid air flow passage is provided with a lead valve (a check valve)
80
, shown in
FIG. 12
, for only allowing the air to flow toward the scavenging flow passage.
In the stratified scavenging two-cycle engine configured as above, a piston
3
ascends, thereby starting to reduce the pressure inside a crank chamber
20
and to increase the pressure inside the cylinder chamber
10
; and as the piston
3
ascends, a scavenging port
81
and an exhaust port are sequentially closed. In this situation, a mixture flows into the crank chamber
20
with the pressure therein being reduced, and air from an air flow passage
83
pushes the lead valve
80
open to flow therein through a scavenging flow passage
85
.
When the piston
3
reaches the vicinity of the top dead center, the mixture in the cylinder chamber
10
is ignited, and thereafter the piston
3
descends. The piston
3
descends, thereby starting to increase the pressure inside the crank chamber
20
; and while the piston
3
is descending, the exhaust port and the scavenging port
81
are sequentially opened, and combustion gas is exhausted via the exhaust port. Subsequently, when the scavenging port
81
is opened, the air remaining in the scavenging flow passage
85
bursts out into the cylinder chamber
10
due to the pressure inside the crank chamber
20
. As a result, the combustion gas remaining in the cylinder chamber
10
is expelled. Subsequently, the mixture in the crank chamber
20
is charged into the cylinder chamber
10
through the scavenging flow passage
85
. Again, when the piston
3
starts to ascend from the bottom dead center, the pressure inside the crank chamber
20
starts to reduce, and the cycle as described above is repeated once again.
According to the stratified scavenging two-cycle engine configured as above, the inside of the cylinder chamber
10
can be initially scavenged by air, thereby making it possible to prevent the combustible gas from being discharged by the blow-by of the mixture, which provides the advantage that the exhaust gas becomes clean.
However, in the aforesaid stratified scavenging two-cycle engine, as shown in
FIG. 12
, the air flowing into the scavenging flow passage
85
from the lead valve
80
does not flow into a space
81
A in the vicinity of the scavenging port
81
, and therefore mixture remains in this space. There exists a disadvantage in that the mixture, together with the air remaining in the scavenging flow passage
85
, is discharged from the exhaust port into the atmosphere with the combustion gas via the cylinder chamber
10
when the scavenging port
81
opens in the exhaust stroke in which the piston
3
descends. In addition, the lead valve
80
is provided in the air flow passage
83
, thereby causing a disadvantage in that the lead valve
80
becomes intake resistance when air is taken into the scavenging flow passage
85
. Further, the number of components is increased due to the lead valve
80
, and the structure is complicated, thus causing the disadvantage of increased costs.
SUMMARY OF THE INVENTION
The present invention is made in view of the aforesaid disadvantages, and its object is to provide a stratified scavenging two-cycle engine, which takes in a fuel mixture and scavenging air separately, is capable of doing away with emission of the mixture into the atmosphere by filling a scavenging flow passage with air and reducing intake resistance of air, and is less expensive with the number of components being reduced.
In order to attain the above object, a stratified scavenging two-cycle engine according to the present invention is a stratified scavenging two-cycle engine including an air intake port, scavenging ports, and an exhaust port which are connected to a cylindrical chamber of the engine; a mixture intake port which is connected to a crank chamber; and scavenging flow passages for connecting the cylinder chamber to the crank chamber; and is characterized in that the air intake port is provided at a position which is a predetermined distance away from the scavenging ports toward the crank chamber parallel to axial direction of the cylindrical chamber, and the scavenging ports are connected to the air intake port via the piston to thereby supply air to the scavenging flow passages from the air intake port through the scavenging ports at the time of an intake stroke.
According to the above configuration, the air intake port and the mixture intake port are separately connected to the cylinder chamber and the crank chamber, respectively, and air is supplied to the scavenging flow passages for connecting the cylinder chamber to the crank chamber via the piston, thereby making it possible to fill at least the cylinder chamber side of the scavenging flow passage with air at the time of an intake stroke. In addition, since the air intake port is opened at a lower position which is the predetermined distance away from the scavenging ports toward the crank chamber, when the top portion of the piston opens the scavenging ports at the time of a scavenging stroke, the air intake port is already closed, and therefore neither air nor the mixture flows back to the air flow passage, thus making a lead valve unnecessary.
Accordingly, in the scavenging stroke, the combustion gas can be initially scavenged from the cylinder chamber by means of the air in the scavenging flow passage, and thus the mixture does not flow into the atmosphere. Further, the lead valve for taking air into the scavenging flow passage is not needed, thereby making it possible to reduce the intake resistance of air and the number of components.
Further, the stratified scavenging two-cycle engine can be characterized in that the piston has a channel on the outer perimeter thereof, and the channel connects the scavenging ports to the air intake port and disconnects the mixture intake port from the scavenging ports, at the time of intake stroke.
According to the above configuration, in the intake stroke, since the mixture intake port is disconnected from the scavenging ports, the mixture does not stay in the scavenging flow passages, thus making it possible to fill the scavenging flow passages with air.
Accordingly, in the intake stroke, the combustion gas in the cylinder chamber can be scavenged by means of the air in the scavenging flow passages, and thus the mixture does not leak into the atmosphere.
Furthermore, the stratified scavenging two-cycle engine can be characterized in that the mixture intake port can be opened and closed by the piston.
According to the above configuration, in the scavenging stroke, when the top portion of the piston opens the scavenging ports, the mixture intake port is already closed, whereby the mixture does not flow back to the mixture flow passage, and thus the lead valve can be made unnecessary.
In addition, since the lead valve for supplying the mixture to the crank chamber is not needed, the number of components can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partially cutaway perspective view of a stratified scavenging two-cycle engine of a first embodiment according to the present invention;
FIG. 2
is a sectional view of the stratified scavenging two-cycle engine of the first embodiment according to the present invention, showing a sectional view taken along the
2
—
2
line in
FIG. 1
;
FIG. 3
is a sectional view of the stratified scavenging two-cycle engine of the first embodiment according to the present invention, showing a sectional view taken along the
3
—
3
line in
FIG. 1
;
FIG. 4
is a sectional plan view of the stratified scavenging two-cycle engine of the first embodiment according to the present invention, showing a sectional view taken along the
4
—
4
line in
FIG. 5
;
FIG. 5
is a sectional side view of the stratified scavenging two-cycle engine, which is near the top dead center, of the first embodiment according to the present invention, showing a sectional view taken along the
5
—
5
line in
FIG. 4
;
FIG. 6
is a sectional side view of the stratified scavenging two-cycle engine in
FIG. 5
in a state in which it is near the bottom dead center;
FIG. 7
is a partially cutaway perspective view of a stratified scavenging two-cycle engine of a second embodiment according to the present invention;
FIG. 8
is a sectional plan view of the stratified scavenging two-cycle engine of the second embodiment according to the present invention, showing a sectional view taken along the
8
—
8
line in
FIG. 9
;
FIG. 9
is a sectional side view of the stratified scavenging two-cycle engine, which is near the top dead center, of the second embodiment according to the present invention, showing a sectional view taken along the
9
—
9
line in
FIG. 8
;
FIG. 10
is a partially cutaway perspective view of a stratified scavenging two-cycle engine of a third embodiment according to the present invention;
FIG. 11
is a partially cutaway perspective view of a stratified scavenging two-cycle engine of a fourth embodiment according to the present invention; and
FIG. 12
is a partial sectional view of a conventional stratified scavenging two-cycle engine, showing a sectional view of a lead valve element provided at an air flow passage and a scavenging flow passage.
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be explained with reference to FIG.
1
through
FIG. 11
below. A stratified scavenging two-cycle engine represented by a first embodiment will be initially shown in FIG.
1
through FIG.
6
. In FIG.
1
through
FIG. 6
, a crankcase
2
is provided at the bottom side of a cylinder block
1
. A piston
3
is provided in a cylindrical chamber in the cylinder block
1
so as to be slidably and closely inserted therein, and the piston
3
is connected to a crank
42
in the crankcase
2
via a connecting rod
41
. A space with variable volumetric capacity, which is on the top of the piston
3
in the cylinder block
1
, is a cylinder chamber
10
; and a space, which is under the piston
3
and surrounded by the cylinder block
1
and the crankcase
2
, is a crank chamber
20
. It should be noted that regarding the aforesaid “closely inserted”, a clearance is provided in the illustrations in
FIG. 4
to
FIG. 6
to facilitate the explanation.
Two scavenging flow passages
50
, for connecting the cylinder chamber
10
and the crank chamber
20
, are provided in the cylinder block
1
and the crankcase
2
as shown in FIG.
3
. The scavenging flow passages
50
open into the cylinder chamber
10
(the inner perimeter surface of the cylinder block
1
) as scavenging ports
51
. An air intake port
11
and a mixture intake port
12
are provided in the inner perimeter surface of the cylinder block
1
. The air intake port
11
and the mixture intake port
12
are vertically arranged to be away from each other by a predetermined distance La (see
FIG. 5
) parallel to the axial direction of the cylindrical chamber in the cylinder block
1
. A position at which the air intake port
11
is opened is lower than a position at which scavenging ports
51
are opened by a predetermined distance Lb (see
FIG. 5
) in the axial direction of the cylindrical chamber in the cylinder block
1
. As for the positions at which the scavenging ports
51
are opened, the two scavenging ports
51
are provided at positions which are displaced 90 degrees apart in a direction of the perimeter of the circle as shown in FIG.
4
. The positions of the scavenging port
51
, however, are not necessarily limited to the angle of 90 degrees, but can be appropriately selected according to the positional relationship between the air intake port
11
and the exhaust port
13
, and asymmetrical positions can be selected. Further, the number of the scavenging ports
51
is not limited to two, and only one may be suitable. A width Ba (see
FIG. 5
) of the opening of the scavenging port
51
parallel to the axial direction is formed to be opened less than the predetermined distance La by which the air intake port
11
is separated from the mixture intake port
12
(the width Ba<the predetermined distance La).
The air intake port
11
is opened and closed by the movement of the piston
3
, thereby making it possible to connect it to and cut it off from a channel (passage)
30
formed on the outer perimeter of the piston
3
. The channel
30
is formed on the outer perimeter of the piston
3
in a T-shaped form in side view; and in a plan view, it is formed in the semi-circle of the outer perimeter of the piston
3
with a predetermined depth in plan view, as shown in a plan view in FIG.
4
and in a side view in FIG.
5
.
The T-shaped channel
30
, formed on the outer perimeter of the piston
3
, connects with the air intake port
11
, opened at the position which is lower than the scavenging ports
51
by the predetermined distance Lb, and connects the air intake port
11
to the two scavenging ports
51
at the time of an air intake stroke, thereby allowing air to be taken into the crank chamber
20
through the air intake port
11
, the channel
30
, and the two scavenging flow passages
50
(shown by the solid line arrow Y). At the time of a scavenging stroke, when the top portion of the piston
3
opens the scavenging port
51
, the air intake port
11
is already closed, because the air intake port
11
is opened at the position which is lower than the scavenging ports
51
by the predetermined distance Lb toward the crankcase
20
. For this reason, in the prior art a back-flow is prevented by means of a lead valve
80
; but in the present invention the piston
3
closes the air intake port
11
to thereby prevent air or the mixture from flowing back to an air flow passage, thus making the lead valve
80
unnecessary. Further, since the width Ba of the opening of the scavenging port
51
is smaller than the predetermined distance La by which the air intake port
11
and the mixture intake port
12
are separated, when the T-shaped channel
30
is opened to the mixture intake port
12
at the lower position, an end portion
30
a
of the channel
30
does not connect with the scavenging port
51
, whereby the scavenging port
51
is closed by the piston
3
as shown in FIG.
6
. Accordingly, at the time of an intake stroke, the mixture does not flow into the scavenging flow passage
50
through the channel
30
. As described above, the channel
30
is in a state in which the air intake port
11
is disconnected from the two scavenging ports
51
at the time of the above scavenging stroke (a state in which the piston
3
is in a position which is lowered a little from its position in FIG.
6
). Thereby air is prevented from flowing back to the air intake port
11
, and the mixture intake port
12
is in a state in which it is disconnected from the scavenging ports
51
.
In the above, the aforesaid air intake port
11
and the channel
30
compose the air flow passage for supplying air into the scavenging flow passages
50
.
The mixture intake port
12
is formed almost in a rectangular form in the inner perimeter surface of the cylinder block
1
, and is opened and closed by a skirt portion of the piston
3
. The mixture intake port
12
opens at the time of an intake stroke in which the piston
3
ascends and the pressure inside the crank chamber
20
reduces, thereby allowing the mixture to be taken into the crank chamber
20
(shown by the dotted line arrow W (in FIG.
5
)), and the mixture intake port
12
closes at the time of a scavenging stroke in which the piston
3
descends and the pressure inside the crank chamber
20
increases, thereby preventing the mixture from being blown back to a carburetor side. As a result, a lead valve for preventing the back-flow is not required when a mixture is supplied into the crank chamber
20
.
Further, the cylinder block
1
is provided with an exhaust port
13
which is opened to the cylinder chamber
10
at a position higher than the scavenging ports
51
in the axial direction of the cylindrical chamber in the cylinder block
1
, as shown in FIG.
2
and FIG.
6
.
In the stratified scavenging two-cycle engine configured as above, as a result that the piston
3
ascends from the bottom dead center (the position near that shown in FIG.
6
), the pressure in the crank chamber
20
starts to reduce while the pressure in the cylinder chamber
10
starts to rise, and the scavenging ports
51
and the exhaust port
13
close in order. In this situation, as shown in
FIG. 5
, in the position near the lower position of the top dead center, the air intake port
11
is in a state in which it is connected to the scavenging flow passages
50
via the channel
30
and the scavenging ports
51
, and the mixture intake port
12
is open to the crank chamber
20
. As a result, air is absorbed into the crank chamber
20
from the air intake port
11
through the channel
30
and the scavenging flow passages
50
. In this situation, the mixture still remaining in the scavenging flow passages
50
is swept into the crank chamber
20
by the air, and thus the scavenging flow passages
50
are filled with air.
When the piston
3
further ascends and reaches the vicinity of the top dead center, the mixture in the cylinder chamber
10
is ignited to explode, whereby the piston
3
starts to descend. The pressure in the crank chamber
20
then starts to rise, with the channel
30
being shut to the air intake port
11
and the scavenging port
51
, and with the mixture intake port
12
being closed by the piston
3
, the piston
3
descends, thereby increasing the pressure in the crank chamber
20
. In this situation, even if the pressure in the crank chamber
20
rises, the air in the scavenging flow passages
50
is not blown back to the air intake port
11
side, and the mixture in the crank chamber
20
is not blown back to the carburetor side.
Further, during the descent of the piston
3
, the exhaust port
13
and the scavenging ports
51
are opened to the cylinder chamber
10
in order, and initially, combustion gas is discharged from the exhaust port
13
. Subsequently, when the scavenging ports
51
are opened to the cylinder chamber
10
, the air remaining in the scavenging flow passages
50
bursts out into the cylinder chamber
10
due to the increased pressure in the crank chamber
20
. Thereby, the residual combustion gas in the cylinder chamber
10
is expelled into the atmosphere from the exhaust port
13
via a muffler. Subsequently, the mixture in the crank chamber
20
is charged into the cylinder chamber
10
through the scavenging flow passages
50
.
Again, the piston
3
starts to ascend from the bottom dead center to thereby start to reduce the pressure in the crank chamber
20
to close the scavenging ports
51
and the exhaust port
13
in order, thus repeating the above cycle once again.
Accordingly, the lead valve conventionally used for taking air into the scavenging flow passages
50
is not required, thereby making it possible to reduce the intake resistance of air and the number of components. Since the channel
30
is connected to the scavenging ports
51
when air is taken in, the mixture is prevented from remaining in the scavenging flow passages
50
. Consequently, in the exhaust stroke, unlike the situation in which the lead valve is used as in the prior art, the combustion gas remaining in the cylinder chamber
10
can be expelled into the atmosphere by the air filling the scavenging flow passages
50
, thus preventing the mixture from being emitted into the atmosphere. Further, the channel
30
can be simultaneously formed when the piston
3
is manufactured by casting, and thereby providing the channel
30
does not increase a burden, for example, in the manufacturing thereof.
In addition, since the lead valve is not used, failures relating to the lead valve are eliminated, thus making it possible to increase reliability. Further, the space for placing the lead valve is not needed, thereby making it easy to reduce the size. Furthermore, timing for introducing air can be controlled by means of the channel
30
provided in the piston
3
, thereby making it possible to facilitate the optimization of the quantity of air and mixture.
Next, a second embodiment of the present invention will be explained with reference to
FIG. 7
,
FIG. 8
, and FIG.
9
. It should be noted that the elements common to those in the above first embodiment will be given the same numerals and symbols, and the explanation thereof will be omitted. A point in which the second embodiment differs from the first embodiment is that in the first embodiment, the air intake port
11
and the mixture intake port
12
are vertically arranged, but in the second embodiment, two of air intake ports
11
A and
11
B are positioned laterally with the mixture intake port
12
between them. As in the first embodiment, the positions, at which the air intake ports
11
A and
11
B are opened, are lower than the positions at which the scavenging ports
51
are opened by the predetermined distance Lb parallel to the axial direction of the cylindrical chamber in the cylinder block
1
as shown in FIG.
9
. The positions, at which the scavenging ports
51
are opened, are displaced by the angle of 90 degrees respectively in the circumferential direction as shown in
FIG. 8
, as in the first embodiment. A through-hole
31
for the mixture is formed in the piston
3
, and two L-shaped channels
30
A and
30
B for air are also formed therein at symmetrical positions with the through-hole
31
between them. The mixture intake port
12
is connected to the crank chamber
20
in the intake stroke via the through-hole
31
provided in the piston
3
. The two left and right air intake ports
11
A and
11
B are connected in the intake stroke to the L-shaped channels
30
A and
30
B, respectively extending to the left and right along the outer perimeter of the piston
3
.
In the stratified scavenging two-cycle engine configured as above, the same operational effects as in the aforesaid first embodiment are provided.
Next, a third embodiment of the present invention will be explained with reference to FIG.
10
. It should be noted that the elements common to those in the aforesaid first embodiment will be given the same numerals and symbols, and the explanation thereof will be omitted. A point in which the third embodiment differs from the first embodiment is that in the first embodiment, the air intake port
11
and the mixture intake port
12
are vertically arranged, but in the third embodiment, the air intake port
11
is constructed by piping. The air intake port
11
is placed at a position which is lower by the predetermined distance Lb, than the positions at which the scavenging ports
51
are opened, and is connected to the channel
30
which extends laterally along the outer perimeter of the piston
3
. Accordingly, the air intake port
11
can be provided at any position in the circumferential direction.
In the stratified scavenging two-cycle engine configured as above, the same operational effects as in the aforesaid first embodiment are provided.
Next, a fourth embodiment of the present invention will be explained with reference to FIG.
11
. It should be noted that the elements common to the aforesaid third embodiment will be given the same numerals and symbols, and the explanation thereof will be omitted. A point in which the fourth embodiment differs from the first embodiment is that in the first embodiment, the air intake port
11
and the mixture intake port
12
are vertically arranged, and the mixture intake port
12
is opened and closed by the piston
3
, but in the fourth embodiment, a mixture intake port
12
A is directly connected to the crank chamber
20
, and the back-flow of the supplied mixture is controlled by the known lead valve (the check valve) not illustrated.
In the stratified scavenging two-cycle engine configured as above, the same operational effects as in the aforesaid first embodiment are also provided.
In the stratified scavenging two-cycle engine configured as above, air can be supplied into the scavenging ports
51
via the channel
30
of the piston
3
, thereby making it possible to fill at least the cylinder chamber
10
side of the scavenging flow passage
51
with air. It is preferable to push the combustion gas out by filling the scavenging flow passages
50
or part of the cylinder chamber
10
connecting to the scavenging flow passages
50
. Consequently, in the scavenging stroke, the combustion gas in the cylinder chamber
10
can be initially scavenged by air, thus making it possible to prevent the mixture remaining in the scavenging flow passages
50
from discharging therefrom as in the case in which the conventional lead valve
80
is used.
In each of the above embodiments, the passage connecting the air intake port
11
and the scavenging ports
51
is composed of the channel
30
, but this passage can be, for example, in the form of a hole which is constructed to penetrate the piston
3
to connect the air intake port
11
and the scavenging ports
51
. Further, the passage (the channel
30
) is constructed to connect to with the scavenging flow passages
50
via the scavenging ports
51
, but the passage (the channel
30
) can be constructed to connect with some midpoint in the scavenging flow passages
50
.
INDUSTRIAL AVAILABILITY
The present invention is useful as a stratified scavenging two-cycle engine, which takes in a mixture and scavenging air separately, is capable of doing away with emission of the mixture into the atmosphere and reducing intake resistance of air, and is less expensive with the number of components being reduced.
Claims
- 1. A stratified scavenging two-cycle engine including a cylinder block having a cylinder chamber therein, said cylinder block having a sidewall which at least partially defines said cylinder chamber, said sidewall having therein an air intake port, at least one scavenging port, and an exhaust port,a mixture intake port for communication with a crank chamber, and at least one scavenging flow passage for connecting the cylinder chamber to the crank chamber, wherein each scavenging port is an opening in said sidewall at a first position, wherein the air intake port is an opening in said sidewall at a second position which is a predetermined distance away from said first position toward the crank chamber parallel to an axial direction of said cylinder chamber in said cylinder block such that a position of a piston at which said air intake port is opened by movement of said piston is lower than a position of said piston at which said at least one scavenging port is opened by movement of said piston, and wherein the at least one scavenging port is connected to the air intake port through a piston to thereby supply air from the air intake port opening in said sidewall via the piston to and through each scavenging port opening to a scavenging flow passage at the time of an intake stroke.
- 2. A stratified scavenging two-cycle engine including an air intake port, scavenging ports, and an exhaust port which are connected to a cylinder chamber of the engine,a mixture intake port for communication with a crank chamber, and scavenging flow passages for connecting the cylinder chamber to the crank chamber, wherein the air intake port is provided at a position which is a predetermined distance away from the scavenging ports toward the crank chamber parallel to an axial direction of the cylinder chamber in a cylinder block, and the scavenging ports are connected to the air intake port through a piston to thereby supply air to the scavenging flow passages from the air intake port through the scavenging ports at the time of an intake stroke, wherein the piston has a channel in the outer perimeter thereof, and the channel connects the scavenging ports to the air intake port and disconnects the mixture intake port from the scavenging ports, at the time of an intake stroke.
- 3. A stratified scavenging two-cycle engine in accordance with claim 2, wherein the mixture intake port is opened and closed by the piston.
- 4. A stratified scavenging two-cycle engine including an air intake port, scavenging ports, and an exhaust port which are connected to a cylinder chamber of the engine,a mixture intake port for communication with a crank chamber, and scavenging flow passages for connecting the cylinder chamber to the crank chamber, wherein the air intake port is provided at a position which is a predetermined distance away from the scavenging ports toward the crank chamber parallel to an axial direction of the cylinder chamber in a cylinder block, and the scavenging ports are connected to the air intake port through a piston to thereby supply air to the scavenging flow passages from the air intake port through the scavenging ports at the time of an intake stroke, wherein the mixture intake port is opened and closed by the piston.
- 5. A stratified scavenging two-cycle engine comprising:a cylinder block having a cylindrical chamber formed therein; a crankcase connected to said cylinder block; a piston slidably positioned in said cylindrical chamber; said piston and said cylinder block defining a cylinder chamber at one end of said piston; said piston, said cylinder block, and said crankcase defining a crank chamber at a second end of said piston; wherein said cylinder block includes at least one air intake port, scavenging ports, and an exhaust port which are formed therein and which open to said cylindrical chamber; wherein said engine has a mixture intake port for communication with said crank chamber; wherein at least one of said cylinder block and said crankcase includes scavenging flow passages for connecting the cylinder chamber to the crank chamber wherein; wherein said at least one air intake port is located in said cylinder block at a position which is a distance away from said scavenging ports in a direction toward said crank chamber which is parallel to an axial direction of said cylindrical chamber; wherein said scavenging ports can be connected to said air intake port via said piston to thereby supply air from said air intake port through said scavenging ports to said scavenging flow passages during a time of an intake stroke; and wherein said mixture intake port is opened and closed by movement of said piston.
- 6. A stratified scavenging two-cycle engine comprising:a cylinder block having a cylindrical chamber formed therein; a crank case connected to said cylinder block; a piston slidably positioned in said cylindrical chamber; said piston and said cylinder block defining a cylinder chamber at one end of said piston; said piston, said cylinder block, and said crankcase defining a crank chamber at a second end of said piston; wherein said cylinder block includes at least one air intake port, scavenging ports, and an exhaust port which are formed therein and which open to said cylindrical chamber; wherein said engine has a mixture intake port for communication with said crank chamber; wherein at least one of said cylinder block and said crankcase includes scavenging flow passages for connecting the cylinder chamber to the crank chamber; wherein said at least one air intake port is located in said cylinder block at a position which is a distance away from said scavenging ports in a direction toward said crank chamber which is parallel to an axial direction of said cylindrical chamber; wherein said scavenging ports can be connected to said air intake port via said piston to thereby supply air from said air intake port through said scavenging ports to said scavenging flow passages during a time of an intake stroke; and wherein said piston has at least one channel formed in an outer perimeter of said piston, and wherein at a time of an intake stroke said at least one channel can connect said scavenging ports to said at least one air intake port and said piston can disconnect said mixture intake port from said scavenging ports.
- 7. A stratified scavenging two-cycle engine in accordance with claim 6, wherein said at least one air intake port comprises two air intake ports, wherein said piston has two channels formed in an outer perimeter of said piston, and wherein each of said channels can connect a respective one of said air intake ports to a respective one of said scavenging ports.
- 8. A stratified scavenging two-cycle engine in accordance with claim 6, wherein said mixture intake port is opened and closed by movement of said piston.
- 9. A stratified scavenging two-cycle engine in accordance with claim 8, wherein said at least one air intake port comprises two air intake ports, wherein said piston has two channels formed in an outer perimeter of said piston, and wherein each of said channels can connect a respective one of said air intake ports to a respective one of said scavenging ports.
- 10. A stratified scavenging two-cycle engine in accordance with claim 6, wherein said piston has a channel formed in an outer perimeter of said piston, said channel having a T-shape when viewed in a side view of said piston, and said channel extending around a portion of an outer periphery of said piston when viewed in a plan view of said piston, wherein at a time of an intake stroke said channel can connect said scavenging ports to said at least one air intake port and disconnect said mixture intake port from said scavenging ports.
- 11. A stratified scavenging two-cycle engine in accordance with claim 6, wherein said at least one air inlet port comprises two air inlet ports, and wherein said piston has two channels formed in an outer perimeter of said piston, each said channel having an L-shape when viewed in a side view of said piston, and each said channel extending around a portion of a periphery of said piston when viewed in a plan view of said piston, wherein at a time of an intake stroke each said channel can connect a respective one of said air intake ports to a respective scavenging port and disconnect said mixture intake port from said scavenging ports.
- 12. A stratified scavenging two-cycle engine comprising:a cylinder block having a cylindrical chamber formed therein; a crankcase connected to said cylinder block; a piston slidably positioned in said cylindrical chamber; said piston and said cylinder block defining a cylinder chamber at one end of said piston; said piston, said cylinder block, and said crankcase defining a crank chamber at a second end of said piston; wherein said cylinder block includes at least one air intake port, scavenging ports, and an exhaust port which are formed therein and which open to said cylindrical chamber; wherein said engine has a mixture intake port for communication with said crank chamber; wherein at least one of said cylinder block and said crankcase includes scavenging flow passages for connecting the cylinder chamber to the crank chamber; wherein said at least one air intake port is located in said cylinder block at a position which is a distance away from said scavenging ports in a direction toward said crank chamber which is parallel to an axial direction of said cylindrical chamber; wherein said scavenging ports can be connected to said air intake port via said piston to thereby supply air from said air intake port through said scavenging ports to said scavenging flow passages during a time of an intake stroke; and wherein a position at which an air intake port is opened by movement of said piston is lower than a position at which scavenging ports are opened by movement of said piston.
- 13. A stratified scavenging two-cycle engine in accordance with claim 12, wherein said distance, between said at least one air intake port and said scavenging ports in a direction toward said crank chamber which is parallel to an axial direction of said cylindrical chamber, is greater than an opening width of said scavenging ports parallel to said axial direction of said cylindrical chamber.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-153927 |
Jun 1997 |
JP |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/JP98/02478 |
|
WO |
00 |
12/10/1999 |
12/10/1999 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO98/57053 |
12/17/1998 |
WO |
A |
US Referenced Citations (11)
Foreign Referenced Citations (5)
Number |
Date |
Country |
2650834 A1 |
Jun 1977 |
DE |
57-181929 A |
Nov 1982 |
JP |
60-194149 U |
Dec 1985 |
JP |
63-195368 A |
Aug 1988 |
JP |
4-109425 U |
Sep 1992 |
JP |