Title: Oil separator for engine, and personal watercraft
Abstract: An oil separator comprises an oil chamber having a first space on an upper side and a second space on a lower side which communicate with each other. An air-fuel mixture transport pipe is connected to a peripheral portion of the oil chamber so as to communicate with the second space. An oil discharge pipe is connected to a lower end portion of the oil chamber. A blow-by gas discharge pipe is connected to an upper end portion of the oil chamber. The second space communicates with the first space so as to inhibit the oil from flowing from the second space into the first space. The first space communicates with the blow-by gas discharge pipe so as to inhibit the oil from flowing from the first space into the blow-by gas discharge pipe. The flow direction at one end portion of the air-fuel mixture transport pipe substantially corresponds with the circumferential direction of the oil chamber.
Patent Number: 6,892,716 Issued on 05/17/2005 to Matsuda, et al.
| Inventors:
|
Matsuda; Yoshimoto (Kobe, JP);
Okada; Yasuo (Akashi, JP)
|
| Assignee:
|
Kawasaki Jukogyo Kabushiki Kaisha (Kobe, JP)
|
| Appl. No.:
|
645477 |
| Filed:
|
August 20, 2003 |
Foreign Application Priority Data
| Aug 23, 2002[JP] | 2002-242997 |
| Oct 29, 2002[JP] | 2002-314352 |
| Current U.S. Class: |
123/572 |
| Intern'l Class: |
B63H 011/00 |
| Field of Search: |
123/572-574
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: McMahon; Marguerite
Attorney, Agent or Firm: Alleman Hall McCoy Russell & Tuttle LLP
Claims
1. An oil separator for an engine, which is configured to separate a liquid from
a gas, comprising:
a tubular oil chamber provided with its center axis extending substantially in
a vertical direction, the oil chamber having closed upper and lower opening ends;
an air-fuel mixture transport pipe connected to a peripheral portion of the oil
chamber so as to communicate with an inner space thereof, the air-fuel mixture
transport pipe being configured to transport a liquid air-fuel mixture into the
oil chamber;
a gas discharge pipe connected to an upper end portion of the oil chamber so
as to communicate with the inner space thereof, to allow the gas to be discharged
from the oil chamber through the gas discharge pipe,
a liquid discharge pipe connected to a lower end portion of the oil chamber so
as to communicate with the inner space thereof, to allow the liquid to be discharged
from the oil chamber through the liquid discharge pipe; and
a separating member provided in the inner space within the oil chamber to define
a first space on an upper side and a second space on a lower side;
wherein the separating member is provided with a penetrating hole to allow the
first space and the second space to communicate with each other, an upper end portion
of a pipe member is connected to a lower face of the separating member so as to
communicate with the penetrating hole, and a lower end portion of the pipe member
opens downwardly;
wherein a connecting end portion of the gas discharge pipe protrudes into the
first space and opens downwardly within the oil chamber; and
wherein a connecting end portion of the air-fuel mixture transport pipe is placed
in the vicinity of an inner peripheral face of the oil chamber and located higher
than the lower end portion of the pipe member such that the connecting end portion
communicates with the second space of the oil chamber and opens in a circumferential
direction of the oil chamber.
2. The oil separator for an engine according to claim 1, wherein the penetrating
hole has a diameter smaller than a diameter of the upper end portion of the pipe member.
3. The oil separator for an engine according to claim 1, wherein the connecting
end portion of the gas discharge pipe has a diameter smaller than a diameter of
the lower end portion of the pipe member.
4. The oil separator for an engine according to claim 1, wherein the liquid air-fuel
mixture is a blow-by gas of the engine.
5. The oil separator for an engine according to claim 1, being equipped in the
engine mounted in a jet-propulsion personal watercraft.
6. An oil separator for an engine, which is configured to separate a liquid from
a gas, comprising:
a tubular oil chamber provided with its center axis extending substantially in
a vertical direction, the oil chamber having closed upper and lower opening ends;
an air-fuel mixture transport pipe connected to a peripheral portion of the oil
chamber so as to communicate with an inner space thereof, the air-fuel mixture
transport pipe being configured to transport a liquid air-fuel mixture into the
oil chamber;
a gas discharge pipe connected to an upper end portion of the oil chamber so
as to communicate with the inner space thereof, to allow the gas to be discharged
from the oil chamber through the gas discharge pipe; and
a liquid discharge pipe connected to a lower end portion of the oil chamber so
as to communicate with the inner space thereof, to allow the liquid to be discharged
from the oil chamber through the liquid discharge pipe;
wherein a connecting end portion of the gas discharge pipe opens downwardly within
the oil chamber;
wherein a connecting end portion of the air-fuel mixture transport pipe is placed
in the vicinity of an inner peripheral face of the oil chamber so as to open in
a circumferential direction of the oil chamber; and
wherein the oil chamber is configured such that opening ends of a tubular member
are closed by closing members having an identical shape.
7. The oil separator for an engine according to claim 6, wherein the tubular
member is cylindrical.
8. A personal watercraft comprising:
a body formed by a hull and a deck covering the hull from above, the body having
an engine room inside thereof;
an engine body mounted within the engine room, the engine body having an associated
crankshaft, a crankcase configured to accommodate the crankshaft, and an oil pan
provided under the crankcase, the engine body being mounted such that the crankshaft
extends along a longitudinal direction of the body;
an air-intake system configured to draw air taken in from outside into the engine
body;
an oil separator configured to separate a blow-by gas discharged from the engine
body into a gas and a liquid;
an air-fuel mixture transport pipe configured to connect the oil separator to
the engine body;
a blow-by gas discharge pipe configured to connect an upper end portion of the
oil separator to the air-intake system;
an oil discharge pipe configured to connect a lower end portion of the oil separator
to the oil pan of the engine;
wherein the oil separator is located on one of right and left sides of the crankshaft,
and the upper and lower end portions are situated along a substantially vertical
axis that is perpendicular to a center axis of the crankshaft; and
wherein part of the air-intake system is located on an opposite side of the crankshaft
from the oil separator, such that the center axis of the crankshaft is located
laterally intermediate the oil separator and the part of the air-intake system;
and
wherein the blow-by gas discharge pipe extends from the oil separator to the
part of the air-intake system, the blow-by gas discharge pipe being coupled to
the oil separator and to the part of the air-intake system at respective locations
that are laterally remote from the center axis of the crankshaft.
9. The personal watercraft according to claim 8, wherein the part of the air-intake
system is an air cleaner.
10. The personal watercraft according to claim 8,
wherein the oil separator includes a tubular oil chamber extending along the
substantially vertical axis of the oil separator intermediate the upper end portion
and lower end portion of the oil separator;
wherein the air-fuel mixture transport pipe is connected to a peripheral portion
of the oil chamber so as to communicate with an inner space thereof, the air-fuel
mixture transport pipe being configured to transport a liquid air-fuel mixture
into the oil chamber, the air-fuel mixture transport pipe having a connecting end
portion placed in the vicinity of an inner peripheral face of the oil chamber so
as to open in a circumferential direction of the oil chamber;
wherein the blow-by gas discharge pipe is connected to the upper end portion
of the oil separator so as to communicate with the inner space thereof, to allow
the blow-by gas to be discharged from the oil chamber through the blow-by gas discharge
pipe, the blow-by gas discharge pipe having a connecting end portion which opens
downwardly within the oil chamber; and
wherein the oil discharge pipe is connected to the lower end portion of the oil
separator so as to communicate with the inner space thereof, to allow the oil to
be discharged from the oil chamber through the oil discharge pipe.
11. The personal watercraft according to claim 10, wherein the oil separator includes:
a separating member provided in the inner space within the oil chamber to define
a first space on an upper side and a second space on a lower side;
wherein the separating member is provided with a penetrating hole to allow the
first space and the second space to communicate with each other, an upper end portion
of a pipe member is connected to a lower face of the separating member so as to
communicate with the penetrating hole, and a lower end portion of the pipe member
opens downwardly;
wherein a connecting end portion of the blow-by gas discharge pipe protrudes
into the first space; and
wherein a connecting end portion of the air-fuel mixture transport pipe communicates
with the second space and is located higher than the lower end portion of the pipe
member.
12. A personal watercraft comprising:
a body including a deck and a hull;
an engine room formed inside the body;
an engine body mounted in the engine room, with a crankshaft having a center
axis of rotation extending along a longitudinal direction of the body;
an oil pan coupled to the engine body below the crankshaft;
an oil separator fluidically connected to the oil pan by an oil discharge pipe,
the oil separator being positioned above and laterally to a side of a center of
the oil pan; and
an air-intake component fluidically connected to the oil separator by a blow-by
gas pipe, the air-intake component being positioned above and laterally on an opposite
side of the oil pan center from the oil separator, wherein an upper end of the
air intake component is lower than an upper end of the oil separator.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oil separator for an engine which is configured
to separate a liquid from a gas, and a personal watercraft comprising the oil separator.
2. Description of the Related Art
In recent years, four-cycle engines have been mounted in certain jet-propulsion
personal watercraft provided with water jet pumps. In the engines, the internal
crankcase pressure varies with the reciprocation of pistons. Accordingly, the engine
is provided with a breather passage to reduce an increased internal pressure of
the crankcase. The breather passage is connected to an air-intake system such as
an air cleaner box to inhibit an excessive increase in the internal pressure of
the crankcase.
Meanwhile, a chamber of the crankcase or an inside of a cylinder head
connected to the chamber of the crankcase through a chain tunnel or the like, is
full of oil in a mist state (oil mist). In order to inhibit a blow-by gas of the
engine that contains the oil mist (hereinafter referred to as a liquid air-fuel
mixture) from flowing into the air cleaner box through the breather pipe and the
oil in the blow-by gas from flowing into the air-intake system, the breather passage
of the engine is typically provided with an oil separator for separating the liquid
air-fuel mixture into the oil and the gas.
The oil separator is configured to have an oil chamber having an inner space
of a predetermined volume which is typically separated by a number of separating
plates, thus forming a labyrinth structure. The blow-by gas with the oil mist that
flows into the oil separator flows along passages formed by the separating plates
provided within the inner space. While flowing along the passages, the oil contained
in the blow-by gas collides with the separating plates and adheres to these plates.
In this manner, the liquid air-fuel mixture flowing into the oil separator is separated
into the gas and the oil. The gas is drawn into the air-intake system through the
breather passage, and the oil is returned to an oil pan through an oil return passage.
In the conventional engine, as disclosed in Japanese Patent No. 3124743, an oil
separator is provided at a connecting face between a crankcase and an oil pan,
or a chamber independently provided within a cylinder head is configured to have
a labyrinth-structured inner space which functions as an oil separator.
By the way, in the case of the jet-propulsion personal watercraft, a vertical
dimension of the engine is inevitably limited because of restrictions such as a
narrow inner space or center of gravity of a body. However, when the oil separator
is provided at the above described location, the vertical dimension of the engine
tends to be increased. Such an engine is difficult to mount in the narrow inner
space within the body.
In the conventional oil separator having a labyrinth structure, the passages
formed
by a number of separating plates are relatively narrow, and are sometimes clogged
with the separated oil. The oil that has clogged the passages is pushed into the
breather passage by the blow-by gas and is carried into the air-intake system.
When the oil pan has a sufficient volume, the oil is also separated from the
gas within an inner space of the oil pan. However, since the vertical dimension
of the engine of the personal watercraft is limited as described above, a sufficient
volume of the oil pan is difficult to gain. When the liquid air-fuel mixture that
contains relatively large amount of oil might flow into the conventional oil separator
having a labyrinth structure, the oil is not satisfactorily separated from the gas.
SUMMARY OF THE INVENTION
The present invention addresses the above described conditions, and an object
of the present invention is to provide an oil separator having a high capability
of separating a liquid air-fuel mixture into a gas and oil and being manufactured
with high productivity, without increasing a vertical dimension of an engine, and
a jet-propulsion personal watercraft in which the engine provided with the oil
separator is mounted.
According to the present invention, there is provided an oil separator
for an engine which is configured to separate a liquid from a gas, comprising a
tubular oil chamber provided with its center axis extending substantially in a
vertical direction, the oil chamber having closed upper and lower opening ends;
an air-fuel mixture transport pipe connected to a peripheral portion of the oil
chamber so as to communicate with an inner space thereof, the air-fuel mixture
transport pipe being configured to transport a liquid air-fuel mixture into the
oil chamber; a gas discharge pipe connected to an upper end portion of the oil
chamber so as to communicate with the inner space thereof, to allow the gas to
be discharged from the oil chamber through the gas discharge pipe; and a liquid
discharge pipe connected to a lower end portion of the oil chamber so as to communicate
with the inner space thereof, to allow the liquid to be discharged from the oil
chamber through the liquid discharge pipe, wherein a connecting end portion of
the gas discharge pipe opens downwardly within the oil chamber, and a connecting
end portion of the air-fuel mixture transport pipe is placed in the vicinity of
an inner peripheral face of the oil chamber so as to open in a circumferential
direction of the oil chamber.
In the oil separator so configured, the liquid air-fuel mixture (e.g., blow-by
gas containing oil mist) is blown into the oil chamber in the circumferential direction
through the air-fuel mixture transport pipe. As a result, the oil mixed in the
gas adheres to an inner peripheral face of the oil chamber by a centrifugal force.
Thus, the oil is separated from the gas. The separated gas is discharged from the
gas discharge pipe located above and the separated oil is discharged from the liquid
discharge pipe located below. Unlike in the conventional oil separator, the oil
separator of the present invention does not have a labyrinth structure provided
with the passages that would be clogged with the separated oil.
Since the oil separator can be externally attached on the engine body, the
height of the engine body need not be increased, and therefore, such an oil separator
is suitable for use in the personal watercraft having a limited inner space. The
separating capability of the oil separator is less affected by the amount of oil
mist contained in the blow-by gas.
The connecting end portion of the gas discharge pipe may protrude into the inner
space of the oil chamber, and the air-fuel mixture transport pipe may open at a
location higher than an opening end of the gas discharge pipe.
In the oil separator so configured, the connecting end portion of the gas discharge
pipe protrudes into an inside of the oil chamber so as to open downwardly, and
the oil moving downwardly by gravity within the oil chamber is inhibited from flowing
from the oil chamber into the gas discharge pipe. In addition, since the connecting
end portion of the air-fuel mixture transport pipe is located higher than the opening
end of the gas discharge pipe, and a flow direction at the connecting end of the
transport pipe differs from a flow direction at the opening end of the gas discharge
pipe, the oil mist flowing from the air-fuel mixture transport pipe into the oil
chamber is not discharged directly from the gas discharge pipe, and therefore,
the amount of oil contained in the gas being discharged can be reduced.
The oil separator may further comprise a separating member provided in the inner
space within the oil chamber to define a first space on an upper side and a second
space on a lower side, and the separating member may be provided with a penetrating
hole to allow the first space and the second space to communicate with each other,
an upper end portion of a pipe member may be connected to a lower face of the separating
member so as to communicate with the penetrating hole, and a lower end portion
of the pipe member may open downwardly, the connecting end portion of the gas discharge
pipe may protrude into the first space, and the connecting end portion of the air-fuel
mixture transport pipe may communicate with the second space and is located higher
than the lower end portion of the pipe member.
In the oil separator so configured, the liquid air-fuel mixture flowing into
the
oil separator is first separated into the oil and the gas within the second space
and is further separated into the oil and the gas within the first space. Therefore,
the liquid air-fuel mixture is reliably separated into the oil and the gas.
The penetrating hole may have a diameter smaller than a diameter of the upper
end portion of the pipe member. In the oil separator so configured, since the passage
extending from the pipe member to the first space through the penetrating hole
is configured to have a diameter reduced at the penetrating hole, the oil within
the second space is inhibited from flowing into the first space through the penetrating
hole. Therefore, the liquid air-fuel mixture is reliably separated into the oil
and the gas.
The connecting end portion of the gas discharge pipe may have a diameter smaller
than a diameter of the lower end portion of the pipe member. In the oil separator
so configured, an exit of the first space (connecting end portion of the gas discharge
pipe) has a diameter smaller than a diameter of an exit of the second space (lower
end portion of the pipe member). Such a structure inhibits the oil from being discharged
from the gas discharge pipe.
The oil chamber may be configured such that the opening ends of a tubular member
are closed by closing members having an identical shape. In the oil separator so
configured, common parts may be used for the closing members, and therefore, productivity
is increased.
The oil chamber may be configured such that the opening ends of a tubular member
are closed by closing members having a shape identical to a shape of the separating
member. In the oil separator so configured, common parts may be used for the closing
members and the separating member, and therefore, productivity is increased.
The tubular member may be cylindrical. In the cylindrical oil separator, since
the liquid air-fuel mixture flows smoothly in the circumferential direction along
the inner peripheral face of the oil chamber, the oil is reliably separated from
the liquid air-fuel mixture by a centrifugal force. In addition, commercially available
cylindrical pipe may be used as the oil separator, and therefore, productivity
is increased.
The liquid air-fuel mixture may be a blow-by gas of the engine. The oil is reliably
separated from the blow-by gas with the above mentioned configuration.
The oil separator may be equipped in the engine mounted in a jet-propulsion personal
watercraft. Since the engine has the oil separator, the vertical dimension of the
engine is not increased. Such an engine is suitable for use in a limited inner
space of the personal watercraft.
According to the present invention, there is further provided a personal
watercraft comprising a body formed by a hull and a deck; an engine body mounted
in the body; an air-intake system configured to draw air taken in from outside
into the engine body; and an oil separator configured to separate a blow-by gas
discharged from the engine body into a gas and a liquid, the oil separator including
a tubular oil chamber provided with its center axis extending substantially in
a vertical direction, the oil chamber having closed upper and lower opening ends;
an air-fuel mixture transport pipe connected to a peripheral portion of the oil
chamber so as to communicate with an inner space thereof, the air-fuel mixture
transport pipe being configured to transport the blow-by gas from the engine body
into the oil chamber; a blow-by gas discharge pipe connected to an upper end portion
of the oil chamber so as to communicate with the inner space thereof, to allow
the blow-by gas to be discharged from the oil chamber through the blow-by gas discharge
pipe; and an oil discharge pipe connected to a lower end portion of the oil chamber
so as to communicate with the inner space thereof, to allow the oil to be discharged
from the oil chamber through the oil discharge pipe, wherein a connecting end portion
of the blow-by gas discharge pipe opens downwardly within the oil chamber, and
a connecting end portion of the air-fuel mixture transport pipe is placed in the
vicinity of an inner peripheral face of the oil chamber so as to open in a circumferential
direction of the oil chamber, wherein at least part of the air-intake system is
located on a first side of right and left sides of the body with respect to the
engine body, the oil chamber of the oil separator is placed on a second side of
the right and left sides with respect to the engine body, and the blow-by gas discharge
pipe extends from the oil chamber to the part of the air-intake system located
on the first side with respect to the engine body.
In the personal watercraft so configured, when the personal watercraft is inclined
either to the right or to the left, the oil is inhibited from flowing into the
air-intake system. For example, the air cleaner partially forming the air-intake
system is placed on the right side of the body with respect to the engine body,
and the oil chamber forming the oil separator is placed on the left side. The air
cleaner and the oil chamber are connected to each other through the blow-by gas
discharge pipe. And, the oil separator and the oil pan at the lower portion of
the engine body are connected to each other through the oil discharge pipe.
In this configuration, when the watercraft is inclined to the right side, the
oil separator is located higher than the engine body, and therefore, the oil reserved
in the oil pan does not flow into the oil separator through the oil discharge pipe.
Thus, the oil is inhibited from flowing into the air cleaner. On the other hand,
when the watercraft is inclined to the left, the air cleaner is located higher
than the oil separator, and therefore, the oil is inhibited from flowing into the
air cleaner through the gas discharge pipe.
The above and further objects and features of the invention will more fully be
apparent from the following detailed description with accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a personal watercraft according to an embodiment of
the present invention;
FIG. 2 is a plan view of the personal watercraft in FIG. 1;
FIG. 3 is a side view of an engine;
FIG. 4 is a longitudinal sectional view showing a configuration of an oil separator;
FIG. 5 is a cross-sectional view taken in the direction of arrows along line
V—V in the oil separator in FIG. 3;
FIG. 6 is a longitudinal sectional view showing the oil separator having a single
inner space; and
FIG. 7 is a rear view of an engine, showing placement of the oil separator and
an air cleaner box.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An oil separator according to embodiments of the present invention will be described
with reference to the drawings. Here, a personal watercraft in which an engine
having the oil separator is mounted, will be described with reference to the drawings.
The personal watercraft in FIG. 1 is a straddle-type personal watercraft provided
with a seat straddled by an operator. In the watercraft in FIG. 1, a body
1
of the watercraft comprises a hull
2 and a deck
3 covering the hull
2 from above. A line at which the hull
2 and the deck
3 are
connected over the entire perimeter thereof is called a gunnel line
4. The
gunnel line
4 is located above a waterline
5 of the watercraft.
As shown in FIG. 2, an opening
6, which has a substantially rectangular
shape as seen from above is formed at a substantially center section of the deck
3 in the upper portion of the body
1 such that its longitudinal direction
corresponds with the longitudinal direction of the body
1. A seat
7
is removably mounted over the opening
6.
An engine room
8 is provided in a space defined by the hull
2 and
the deck
3 below the opening
6. An engine E for driving the personal
watercraft is mounted within the engine room
8. The engine room
8
has a convex-shaped transverse cross-section and is configured such that its upper
portion is smaller than its lower portion. In this embodiment, the engine E is
an in-line four-cylinder four-cycle engine. As shown in FIG. 1, the engine E is
mounted such that a crankshaft
9 extends along the longitudinal direction
of the body
1.
An output end of the crankshaft
9 is rotatably coupled integrally with
a pump shaft
11 of a water jet pump P provided on the rear side of the body
1 through a propeller shaft
10. An impeller
12 is attached
on the pump shaft
11. Fairing vanes
13 are provided behind the impeller
12. The impeller
12 is covered with a pump casing
14 on the
outer periphery thereof.
A water intake
15 is provided on the bottom of the body
1. The
water
intake
15 is connected to the pump casing
14 through a water passage.
The pump casing
14 is connected to a pump nozzle
16 provided on the
rear side of the body
1. The pump nozzle
16 has a cross-sectional
area that gradually reduces rearward, and an outlet port
17 is provided
on the rear end of the pump nozzle
16.
The water outside the watercraft is sucked from the water intake
15 and
fed to the water jet pump P. The water jet pump P pressurizes and accelerates the
water and the fairing vanes
13 guide water flow behind the impeller
12.
The water is ejected through the pump nozzle
16 and from the outlet port
17, and, as the resulting reaction, the watercraft obtains a propulsion force.
In FIGS. 1 and 2, reference numeral
18 denotes a bar-type steering handle.
The steering handle
18 is connected to a steering nozzle
19 provided
behind the pump nozzle
16 through a cable
19c (indicated by
a dashed line in FIG.
2). When the rider rotates the handle
18 clockwise
or counterclockwise, the steering nozzle
19 is swung toward the opposite
direction so that the ejection direction of the water being ejected through the
pump nozzle
16 can be changed, and the watercraft can be correspondingly
turned to any desired direction while the water jet pump P is generating the propulsion force.
As shown in FIG. 1, a bowl-shaped reverse deflector
20 is provided on
the
rear side of the body
1 so as to have the steering nozzle
19 inside
the deflector
20 such that it can vertically swing around a horizontally
mounted swinging shaft
21. The deflector
20 is swung downward to
a lower position around the swinging shaft
21 to deflect the ejected water
from the steering nozzle
19 forward, and, as the resulting reaction, the
personal watercraft moves rearward.
In FIGS. 1 and 2, a rear deck
22 is provided in the rear section of the
body
1. The rear deck
22 is provided with an openable rear hatch
cover
23. A rear compartment (not shown) with a small capacity is provided
under the rear hatch cover
23. In FIGS. 1 and 2, a front hatch cover
24
is provided in a front section of the body
1. A front compartment (not shown)
is provided under the front hatch cover
24 for storing equipments and the like.
FIG. 3 is a side view of the engine E. The engine E is an in-line four-cylinder
four-cycle engine as described above. The engine E comprises an engine body
35
having a cylinder head
31 covered by a cylinder head cover
30, a
cylinder block
32, a crankcase
33, and an oil pan
34, which
are arranged and connected to one another in this order, from above.
The engine E comprises an exhaust manifold
36 connected to the cylinder
head
31, an air-intake pipe (not shown), an air-cleaner box
37 provided
behind the engine body
35, and an oil separator
40 provided behind
the engine body
35 and laterally of the air cleaner box
37. The oil
separator
40 serves to separate a blow-by gas containing oil mist (liquid
air-fuel mixture) into a gas and oil, as mentioned later. An inner space of the
cylinder head
31 and a chamber of the crankcase
33 communicate with
each other through a chain tunnel (not shown).
FIG. 4 is a longitudinal sectional view showing a configuration of the oil separator
40, and FIG. 5 is a cross-sectional view taken in the direction of arrows
along line V—V in the oil separator
40 in FIG.
4. As shown
in FIG. 4, the oil separator
40 has an oil chamber
41 that is hollow
and elongate in the vertical direction, i.e., tubular. The oil chamber
41
has a cylindrical tubular member
42 having upper and lower opening ends,
and a bowl-shaped upper end closing member
43 and a bowl-shaped lower end
closing member
44 for closing the upper opening end and the lower opening
end of the tubular member
42, respectively.
More specifically, an edge portion of the upper end closing member
43
is connected to an edge portion of the upper opening end of the tubular member
42 such that the upper end closing member
43 opens downwardly, and
an edge portion of the lower end closing member
44 is connected to an edge
portion of the lower opening end of the tubular member
42 such that the
lower end closing member
44 opens upwardly. As a result, the tubular member
42, the upper end closing member
43, and the lower end closing member
44 form the oil chamber
41 having an inner space. The shape of the
tubular member
42 is not intended to be limited to a cylindrical shape,
but may be a polygon-shaped in transverse cross-section.
A bowl-shaped separating member
45 is provided within the tubular member
42 so as to open upwardly. An edge portion of the separating member
45
is fixed to an inner peripheral portion of the tubular member
42. Within
the inner space of the oil chamber
41, the separating member
45 defines
a first space
46 on the upper side and a second space
47 on the lower side.
A penetrating hole
48 is formed substantially at the center position of
the separating member
45 to allow the first space
46 and the second
space
47 to communicate with each other. An upper end portion of a tubular
pipe member
49 is fixed to a lower face of the separating member
45
so as to communicate with the penetrating hole
48. Therefore, the first
space
46 and the second space
47 communicate with each other so as
to inhibit the oil from flowing from the second space
47 into the first
space
46.
An opening diameter
48D of the penetrating hole
48 is smaller than
an inner diameter
49D of an upper end portion of the pipe member
49.
Because of the smaller diameter of the penetrating hole
48, the oil is inhibited
from moving from the pipe member
49 into the first space
46 through
the penetrating hole
48. A lower end portion of the pipe member
49
opens downwardly, and a flow direction (opening direction) at its opening end (arrow
49Y in FIG. 4) substantially corresponds with the vertical direction.
The upper end closing member
43, the lower end closing member
44,
and the separating member
45 are formed by common parts. Thus, since the
oil separator
40 of this embodiment has a plurality of common parts, productivity
is increased. It should be appreciated that the upper end closing member
43,
the lower end closing member
44, and the separating member
45 are
not intended to be limited to the above mentioned bowl shape, but may be flat-plate shaped.
A penetrating hole
50 is formed substantially at the center position of
the upper end closing member
43. One end portion (connecting end portion)
52 of a blow-by gas discharge pipe (gas discharge pipe)
51 extends
through the penetrating hole
50 to protrude into the first space
46
of the oil chamber
41. The one end portion
52 opens downwardly, and
a flow direction (opening direction) at its opening end (see arrow
52Y in
FIG. 4) substantially corresponds with the vertical direction. Therefore, the upper
end closing member
43 and the blow-by gas discharge pipe
51 are connected
to each other so as to inhibit the oil from flowing from the first space
46
of the oil chamber
41 into the blow-by gas discharge pipe
51.
As shown in FIG. 3, the other end portion
53 of the blow-by gas discharge
pipe
51 is connected to the air cleaner box
37. An opening diameter
52D of the one end portion
52 of the blow-by gas discharge pipe
51
is set smaller than an inner diameter
49D of the pipe member
49.
A penetrating hole
54 is formed substantially at the center position of
the lower end closing member
44. One end portion (connecting end portion)
56 of an oil discharge pipe (liquid discharge pipe)
55 is connected
to a lower face of the lower end closing member
44 so as to communicate
with the penetrating hole
54. The other end portion
57 of the oil
discharge pipe
55 is connected to the oil pan
34 as shown in FIG.
3.
The blow-by gas containing oil mist is transported through a air-fuel mixture
transport pipe
58. One end portion (connecting end portion)
59 of
the air-fuel mixture transport pipe
58 is connected to a peripheral portion
of the oil chamber
41 and the other end portion
60 thereof is connected
to the cylinder head cover
30 as shown in FIG.
3. Therefore, the
oil chamber
41 communicates with the cylinder head
31. In this embodiment,
as shown in FIGS. 4 and 5, the one end portion
59 of the air-fuel mixture
pipe
58 protrudes into the second space
47 within the oil chamber
41.
As shown in FIG. 5, the one end portion
59 of the air-fuel mixture transport
pipe
58 is positioned in the vicinity of the inner peripheral face of the
oil chamber
41. As shown in FIG. 4, the one end portion
59 is configured
to open at a location higher than the lower end of the pipe member
49. The
one end portion
59 opens in the circumferential direction of the tubular
member
42. Therefore, a flow direction (opening direction) at the one end
portion
59 (see arrow
59Y in FIG. 4) substantially corresponds with
the circumferential direction of the tubular member
42.
As shown in FIG. 3, a flow passage of the air-fuel mixture transport pipe
58,
extends downwardly from the other end portion
60 connected to the cylinder
head cover
30 and is turned back at the vicinity of the oil pan
34
so as to extend upwardly to reach the one end portion
59 connected to the
oil chamber
41. Therefore, when the personal watercraft is greatly inclined
to the right or to the left, the oil is inhibited from outflowing from the cylinder
head
31 into the oil separator
40. A bracket
62 having screw
holes
61 is welded to an upper portion of the oil separator
40 and
screwed to a vicinity of the opening
6 on an upper surface of the deck
2
of the body
1 of the watercraft.
In the engine E configured as described above, the flow passage formed by the
air-fuel mixture transport pipe
58, the oil chamber
41, and the blow-by
gas discharge pipe
51 create a breather passage of the engine, and the inner
space of the cylinder head
31 and the inner space of the air cleaner box
37 communicate with each other. In this structure, when an internal pressure
of the crankcase
33 increases, the blow-by gas of the engine E containing
oil mist flows from the cylinder head
31 connected to the crankcase
33
through the chain tunnel into the second space
47 of the oil separator
40
through the air-fuel mixture transport pipe
58.
Inside the second space
47 of the oil separator
40, the blow-by
gas flows along the flow direction
59Y at the one end portion
59
of the air-fuel mixture transport pipe
58, i.e., along the circumferential
direction of the oil chamber
41 (see FIG.
5). The oil mist in the
blow-by gas is separated from the gas by a centrifugal force generated by movement
of the blow-by gas within the oil chamber
41. The separated oil mist is
liquefied and adheres to an inner wall of the oil chamber
41. The separated
oil moves downwardly along the inner wall of the oil chamber
41 and is returned
to the oil pan
34 through the oil discharge pipe
55.
The oil separator
40 utilizes the centrifugal force generated by the movement
of the oil mist along the circumferential direction of the oil chamber
41.
Therefore, even when the blow-by gas containing a large amount of oil mist flows
into the oil separator
40, the oil is reliably separated from the gas. In
addition, the oil separator
40 does not have a labyrinth structure provided
with passages that would be clogged with the separated oil.
Meanwhile, the blow-by gas from which the oil has been separated, moves
from the second space
47 into the first space
46 through the pipe
member
49. As described above, since the opening end of the one end portion
59 of the air-fuel mixture transport pipe
58 is located higher than
the lower end of the pipe member
49, and the flow direction
59Y at
the one end portion
59 (exit portion) of the air-fuel mixture transport
pipe
58 is perpendicular to the flow direction
49Y at the lower end
of the pipe member
49. Therefore, the blow-by gas containing the oil mist
that flows from the air-fuel mixture transport pipe
58 into the second space
47 is inhibited from flowing into the first space
46 directly through
the pipe member
49.
As described above, since the oil is inhibited from flowing from the second space
47 into the pipe member
49, and further, since the oil is inhibited
from flowing from the pipe member
49 into the first space
46 through
the penetrating hole
48 of the separating member
45, the oil is inhibited
from flowing from the second space
47 into the first space
46.
The blow-by gas moving into the first space
46 sometimes contains some
oil mist. But, since the oil mist moves into a wider space of the first space
46
through the penetrating hole
48 of the separating member
45 and expands
therein, separation of the oil from the gas is facilitated. The oil separated within
the first space
46 drops into the second space
47 through the penetrating
hole
48 and the pipe member
49, and is returned to the oil pan
34
through the oil discharge pipe
55.
The blow-by gas from which the oil has been separated within the second space
47 and the first space
46 flows into the air cleaner box
37
through the blow-by gas discharge pipe
51. Since the first space
46
and the blow-by gas discharge pipe
51 communicate with each other so as
to inhibit the oil from flowing from the first space
46 into the blow-by
gas discharge pipe
51 as described above, the oil is further inhibited from
being discharged through the blow-by gas discharge pipe
51.
The oil separator
40 configured as described above is capable of reliably
separating the blow-by gas containing a large amount of oil mist into the oil and
the gas and of inhibiting the oil from flowing into the air-intake system. And,
the separated gas is discharged into the air-intake system and the separated oil
is returned to the oil pan
34. Further, since the oil separator
40
is externally attached on the engine body
35, the height of the engine E
is not increased. Therefore, the oil separator
40 is suitable for use in
a limited space of the personal watercraft.
The oil separator
40 in this embodiment has two inner spaces. Alternatively,
the oil separator
40 may have only one inner space, or three or more inner
spaces. FIG. 6 is a longitudinal sectional view showing an oil separator
70
having only one inner space.
The separating member
45 and the pipe member
49 are not provided
on the oil separator
70 in FIG. 6, unlike in the oil separator
40
in FIG.
4. The blow-by gas discharge pipe
51 protruding through the
penetrating hole
50 of the upper end closing member
43 into the oil
chamber
41 is configured such that one end portion (connecting end portion)
71 extends to a position lower than one end portion
59 of the air-fuel
mixture transport pipe
58. The one end portion
71 opens downwardly,
and a flow direction (opening direction) at the one end portion
71 (see
arrow
71Y in FIG. 6) substantially corresponds with the vertical direction.
In FIG. 6, the same reference numerals as those in FIG. 4 denote the same or corresponding
parts, which will not be further described.
In the oil separator
70 configured as described above, the blow-by gas
containing the oil mist, inflowing from the air-fuel mixture transport pipe
58,
flows along the inner peripheral face of the tubular member
42, as in the
above mentioned oil separator
40. By the centrifugal force, the oil adheres
to the inner wall of the oil chamber
41. Thus, even in the case of the blow-by
gas containing a large amount of oil mist, the oil is well separated from the blow-by gas.
As described above, the one end portion
71 of the blow-by gas discharge
pipe
51 opens at the location lower than the one end portion
59 of
the air-fuel mixture transport pipe
58 and the flow direction
59Y
at the one end portion
59 of the air-fuel mixture transport pipe
58
is perpendicular to the flow direction
71Y at the one end portion
71
of the gas discharge pipe
51, the oil mist flowing from the air-fuel mixture
transport pipe
58 into the oil chamber
41 is inhibited from being
discharged directly through the blow-by gas discharge pipe
51.
By devising placement of the oil separator and the air-intake system, the oil
is inhibited from flowing into the air-intake system. FIG. 7 is a rear view of
the engine E, showing placement of the oil separator
40 and the air cleaner
box
37. As shown in FIG. 7, the oil chamber
41 forming the oil separator
40 is placed on the left side of the watercraft relative to the engine body
35, and the air cleaner box
37 is placed on the right side of the
watercraft relative to the engine body
35.
The one end portion
52 of the blow-by gas discharge pipe
51 is
connected to the oil separator
40, and the other end portion
53 thereof
is connected to the air cleaner box
37. Thus, the blow-by gas discharge
pipe
51 extends from the left side to the right side of the engine E in
FIG.
7. The one end portion
56 of the oil discharge pipe
55
is connected to the oil separator
40, and the other end portion
57
thereof is connected to the oil pan
34 substantially at a center position
in the lateral direction of the engine E.
In the above configuration, when the watercraft is inclined 90 degrees to the
right side, the oil chamber
41 is located higher than the position where
the other end portion
57 of the oil discharge pipe
55 is connected
to the oil pan
34, and therefore, the oil in the oil pan is inhibited from
flowing into the oil chamber
41 through the oil discharge pipe
55.
As a result, the oil is inhibited from flowing from the oil pan
34 into
the air-cleaner box
37 through the oil separator
40. On the other
hand, when the watercraft is inclined 90 degrees to the left, the air cleaner box
37 is located higher than the oil separator
40, and therefore the
oil is inhibited from flowing from the oil chamber
41 into the air cleaner
box
37 through the blow-by gas discharge pipe
51.
As a matter of course, in the configuration in FIG. 7, the oil separator
40
may be replaced by the oil separator
70. Also, in such a configuration,
the positional relationship between the oil separator
40 and the air cleaner
box
37 in the lateral direction may be reversed.
In the configuration in FIG. 7, the blow-by gas discharge pipe
51 is connected
to the air cleaner box
37. Alternatively, the blow-by gas discharge pipe
51 may communicate with other components belonging to the air-intake system,
such as a throttle tube or an air-intake pipe. It should be appreciated that, the
blow-by gas discharge pipe
51 is connected to the air-intake system at a
location on the opposite side of the oil separator
40 with respect to the
engine body
35 in the lateral direction.
As this invention may be embodied in several forms without departing from the
spirit of essential characteristics thereof, the present embodiment is therefore
illustrative and not restrictive, since the scope of the invention is defined by
the appended claims rather than by the description preceding them, and all changes
that fall within the metes and bounds of the claims, or equivalents of such metes
and bounds thereof are therefore intended to be embraced by the claims.
*
