Information
-
Patent Grant
-
6732700
-
Patent Number
6,732,700
-
Date Filed
Monday, August 13, 200123 years ago
-
Date Issued
Tuesday, May 11, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Argenbright; Tony M.
- Harris; Katrina B.
Agents
- Knobbe, Martens, Olson & Bear, LLP
-
CPC
-
US Classifications
Field of Search
US
- 123 196 R
- 123 195 AC
- 123 196 AB
- 123 196 CP
- 123 195 R
- 123 195 C
- 184 106
-
International Classifications
-
Abstract
An oil pump unit for an engine includes an improved construction. The pump unit includes a housing. A scavenge pump assembly is disposed in series with the feed pump assembly to be driven by the pump shaft. The feed and scavenge pump assemblies each defines end portions spaced apart from each other along the shaft axis. The housing defines a first inlet port and at least one outlet port at one of the end portions of the feed pump assembly, a second inlet port and a second outlet port at one of the end portions of the scavenge pump assembly, and at least a third inlet port at the other end portion of the scavenge pump assembly.
Description
RELATED APPLICATION
This application is based on Japanese Patent Application No. 2000-175655, filed on Jun. 12, 2000, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an oil pump unit for an engine, and more particularly to an improved oil pump unit that varies a volume of its own pumping chamber with rotation.
2. Description of Related Art
Relatively small watercraft such as, for example, personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries one or more riders. A hull of the watercraft typically defines a rider's area above an engine compartment. An internal combustion engine powers a jet propulsion unit that propels the watercraft by discharging water rearwardly. The engine lies within the engine compartment in front of a tunnel which is formed on an underside of the hull. The jet propulsion unit is placed within the tunnel and includes an impeller that is driven by the engine.
Typically, the watercraft employs a lubrication system that lubricates portions of the engine. Some lubrication systems form a closed-loop. Such a lubrication system includes an oil tank containing lubricant oil, an oil pan forming a lower wall of a crankcase of the engine to which the lubricant oil that has lubricated the engine portions returns, a feed pump supplying the lubricant oil within the oil tank to the engine portions, and a scavenge pump returning the lubricant oil from the oil pan to the oil tank. Optionally, a trochoid pump construction is applied to the feed and scavenge pumps. Both of the pumps can be unitarily formed within a single housing. For example, respective pump assemblies can be disposed on a common shaft, which is journaled for rotation within the housing and driven by the engine, in series with each other.
In this arrangement, the housing has at least two inlet openings connected to respective inlet ports of the feed and scavenge pumps, and also at least two outlet openings connected to respective outlet ports of the feed and scavenge pumps. Generally, any side surfaces of the housing are available for forming the inlet and outlet openings. The pump unit occasionally is mounted on the engine body because the engine body normally defines both the engines portions which need lubrications and the oil pan therein.
SUMMARY OF THE INVENTION
One aspect of the present invention include the realization that a problem can arise with this arrangement when the pump housing is mounted directly to the engine body such that the internal passages on the housing are connected to internal oil passages in the engine body. In this arrangement, one of the pump which is disposed farther from the engine body than the other pump, necessarily has internal passages that connect the inlet and outlet ports of the pump to the inlet and outlet openings, respectively. The internal passages can produce flow resistance and the pumping ability of the pump is limited to the extent that is regulated by the flow resistance. A larger pump assembly may be useful under a certain engine speed, for example, less than 4,000 rpm to resolve the problem. However, such a larger pump assembly is no longer useful when the engine operates in a high speed range such as, for example, 4,000-7,000 rpm, because the lubricant oil is urged out from pumping chambers of the pump assembly immediately after being drawn into the chambers.
A need therefore exists for an oil pump unit for an engine that offers better performance over a broader range of engine speeds.
In accordance with one another aspect of the present invention, an oil pump unit for an internal combustion engine comprises a housing. A shaft extends within the housing and is journaled thereon for rotation about a shaft axis. The shaft is driven by the engine. An inner rotor is affixed to the shaft to rotate with the shaft. An outer rotor is disposed around the inner rotor to be rotated by the inner rotor. The inner and outer rotors together define at least one pumping chamber. A volume of the pumping chamber varies with the rotation of the inner and outer rotors. The inner rotor has first and second end portions spaced apart from each other along the shaft axis. The outer rotor has third and fourth end portions spaced apart from each other along the shaft axis. The housing defines a first inlet port and at least one outlet port at a location where the first end portion of the inner rotor and the third end portion of the outer rotor are positioned. The first inlet port and the outlet port selectively communicate with the pumping chamber with the rotation of the inner and outer rotors. The housing further defines at least a second inlet port at a location where the second end portion of the inner rotor and the fourth end portion of the outer rotor are positioned.
In accordance with another aspect of the present invention, an oil pump unit for an internal combustion engine comprises a housing. A shaft extends within the housing and is journaled thereon for rotation about a shaft axis. The shaft is driven by the engine. A first pump assembly is disposed on the shaft to be driven by the shaft. A second pump assembly is disposed on the shaft in series with the first pump assembly to be driven by the shaft. The first and second pump assemblies each defines end portions spaced apart from each other along the shaft axis. The housing defines a first inlet port and at least one outlet port at one of the end portions of the first pump assembly, a second inlet port and a second outlet port at one of the end portions of the second pump assembly, and at least a third inlet port at the other end portion of the second pump assembly.
In accordance with a further aspect of the present invention, a lubrication system for an internal combustion engine comprises a first oil reservoir arranged to contain lubricant oil. A second oil reservoir is arranged to receive the lubricant oil that has lubricated portions of the engine. An oil pump unit is arranged to supply the lubricant oil within the first oil reservoir to the portions of the engine and to return the lubricant oil within the second oil reservoir to the primary oil reservoir. The oil pump unit comprises a housing. A shaft extends within the housing and is journaled thereon for rotation about a shaft axis. The shaft is driven by the engine. A feed pump assembly is disposed on the shaft to be driven by the shaft. A scavenge pump assembly is disposed on the shaft in series with the feed pump assembly to be driven by the shaft. The feed and scavenge pump assemblies each defines end portions spaced apart from each other along the shaft axis. The housing defines a first inlet port and a first outlet port at one of the end portions of the feed pump assembly, a second inlet port and a second outlet port at one of the end portions of the scavenge pump assembly, and at least a third inlet port at the other end portion of the scavenge pump assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects and advantages of the present invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention. The drawings comprise 13 figures.
FIG. 1
is a side elevational view of a personal watercraft including an oil pump unit for an engine of the watercraft that is configured in accordance with a preferred embodiment of the present invention.
FIG. 2
is a top plan view of the watercraft of FIG.
1
.
FIG. 3
is a front, top and starboard side perspective view of the engine shown in FIG.
1
.
FIG. 4
is a front, top, and port side perspective view of the engine shown in FIG.
1
.
FIG. 5
is a side elevational view of a rear portion of the engine. The forward portion of the engine and an oil tank are shown in phantom line. A transmission and a gear housing are partially shown in section.
FIG. 6
is a top plan and partial sectional view of the transmission construction and the oil pump unit shown in FIG.
5
. The transmission, the oil pump unit and a portion of the engine body are shown in section. The oil pump unit in this figure is illustrated schematically.
FIG. 7
is a schematic rear view of a gear train of the transmission.
FIG. 8
is a flow chart a lubrication system incorporating the oil pump unit and arranged in accordance with the preferred embodiment of the present invention.
FIG. 9
is a sectional view of the oil pump unit taken along the line
9
—
9
of FIG.
10
.
FIG. 10
is a sectional view of the oil pump taken along the line
10
—
10
of FIG.
9
.
FIG. 11
is a schematic view of a typical trochoid pump construction that is applied to feed and scavenge pump assemblies in the pump unit.
FIG. 12
is a flow chart of a modification of the lubrication system shown in FIG.
8
.
FIG. 13
is a sectional view of a relief valve applied to the feed pump assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
FIGS. 1-7
illustrate an overall construction of a personal watercraft
30
which employs an oil pump unit
32
(
FIG. 6
) for an engine
34
of the watercraft
30
that is configured in accordance with a preferred embodiment of the present invention. The oil pump unit
32
has particular utility in the context of a marine drive, such as the personal watercraft
30
for instance, and thus is described in the context of a personal watercraft
30
. The oil pump
32
, however, can be used with other types of watercrafts or marine drives (i.e., jet boats, outboard motors, inboard/outboard motors, etc.) and also certain land vehicles, which includes lawnmowers, motorcycles, go carts, all terrain vehicles and the like. Furthermore, the oil pump unit
32
can be used for a stationary engine as will become apparent to those of ordinary skill in the art.
The personal watercraft
30
includes a hull
36
formed with a lower hull section
38
and an upper hull section or deck
40
. Both the hull sections
38
,
40
are made of, for example, a molded fiberglass reinforced resin or a sheet molding compound. The lower hull section
38
and the upper hull section
40
are coupled together to define an internal cavity
42
. An intersection of the hull sections
38
,
40
is defined in part along an outer surface gunnel or bulwark
44
. The hull
36
, and in particular, the internal cavity or “engine compartment”
42
, houses the engine
34
that powers the watercraft
30
.
As shown in
FIG. 2
, the hull
36
defines a center plane CP that extends generally vertically from bow to stern and along a longitudinal axis of the watercraft
30
, when the watercraft
30
is resting in a normal upright position. Along the center plane CP, the upper hull section
36
includes a hatch cover
48
, a steering mast
50
and a seat
52
one after another from fore to aft.
In the illustrated embodiment, a bow portion
54
of the upper hull section
40
slopes upwardly rearwardly and an opening (not shown) is provided through which the rider can access a front portion of the internal cavity
42
. The bow portion
54
preferably is formed with a pair of cover member pieces which are split another along the center plane CP. The hatch cover
48
is hinged to open or detachably affixed to the bow portion
54
to cover the opening.
The steering mast
50
extends generally upwardly toward the top of the bow portion
54
to support a handle bar
56
. The handle bar
56
is provided primarily for a rider to control the steering mast
50
so as to turn the watercraft
30
in a known manner. The handle bar
56
also carries control devices such as, for example, a throttle lever
58
(
FIG. 2
) for operating throttle valves of the engine
34
.
The seat
52
extends fore to aft along the center plane CP at a location behind the steering mast
50
. The seat
52
is configured generally as a saddle shape so that the rider can straddle it. Foot areas
60
(
FIG. 2
) are defined on both sides of the seat
52
and at the top surface of the upper hull section
40
. The foot areas
60
are formed generally flat.
A seat cushion
62
, which has a rigid backing and is supported by a pedestal section
64
of the upper hull section
40
, forms a portion of the seat
52
. The pedestal section
64
forms the other portion of the seat
52
. The seat cushion
62
is detachably affixed to the pedestal section
64
.
An access opening
66
(
FIG. 2
) is defined on the top surface of the pedestal section
64
, under the seat cushion
62
, through which the rider can access a rear portion of the internal cavity
42
, i.e., an engine compartment. In other words, the seat cushion
62
usually closes the access opening
66
. In the illustrated embodiment, the upper hull section
40
also defines a storage box
68
under the seat
52
. It is to be noted that the engine compartment can be the whole internal cavity
42
or it can be divided into one or more areas by one or more bulkheads (not shown).
A fuel tank
72
is placed in the internal cavity
42
under the bow portion
54
of the upper hull section
40
. The fuel tank
72
is coupled with a fuel inlet port positioned atop the upper hull section
40
through a fuel duct. A closure cap
74
(
FIG. 2
) closes the fuel inlet port. The opening disposed under the hatch cover
48
is available for accessing the fuel tank
72
.
A pair of air or ventilation ducts
76
is provided on both sides of the bow portion
54
so that the ambient air can enter the internal cavity
42
through the ducts
76
. Except for the air ducts
76
, the internal cavity
42
is substantially sealed to protect the engine
34
, a fuel supply system including the fuel tank
72
and other systems or components from water. Optionally, the watercraft
30
can include other air ducts (not shown).
The engine
34
preferably is placed within the engine compartment
42
and generally under the seat
52
, although other locations are also possible (e.g., beneath the steering mast
50
or in the bow). The rider can access the engine
34
through the access opening
66
by detaching the seat cushion
62
from the pedestal section
64
.
A jet pump assembly
80
propels the watercraft
30
. The jet pump assembly
80
is mounted in a tunnel
82
formed on the underside of the lower hull section
38
. Optionally, a bulkhead can be disposed between the tunnel
82
and the engine
34
.
The tunnel
82
has a downward facing inlet port
84
opening toward the body of water. A jet pump housing
86
is disposed within a portion of the tunnel
82
and communicates with the inlet port
84
. An impeller is journaled within the jet pump housing
86
.
An impeller shaft
87
extends forwardly from the impeller and is coupled with a crankshaft
88
of the engine
34
by a coupling member
89
to be driven by the crankshaft
88
. More specifically, as shown in
FIGS. 5 and 6
, the coupling member
89
preferably is affixed to one end of an intermediate shaft
90
that has a reduction gear
91
on the other end thereof. The crankshaft
88
also has an output gear
92
that meshes with the reduction gear
91
at a rear end of the crankshaft
88
to rotate the intermediate shaft
90
. Because a diameter of the reduction gear
91
is greater than a diameter of the output gear
92
, the intermediate shaft
90
rotates in a reduced speed that is slower than an engine speed made by the crankshaft
88
.
With reference to
FIG. 1
, the rear end of the jet pump housing
86
defines a discharge nozzle
94
. A deflector or steering nozzle
96
is affixed to the discharge nozzle
94
for pivotal movement about a generally vertical steering axis. A cable connects the deflector
96
with the steering mast
50
so that the rider can steer the deflector
96
.
When the crankshaft
88
of the engine
34
drives the impeller shaft
88
and hence the impeller rotates, water is drawn from the surrounding body of water through the inlet port
84
. The pressure generated in the jet pump housing
86
by the impeller produces a jet of water that is discharged through the discharge nozzle
94
and the deflector
96
. The water jet thus produces thrust to propel the watercraft
30
. The rider can steer the deflector
96
with the handle bar
56
of the steering mast
50
so as to turn the watercraft
30
.
The engine
34
preferably operates on a four-cycle combustion principle and preferably has four cylinders spaced apart from one another along the center plane CP. The engine
34
can have a typical and conventional four-cycle engine construction. That is, the engine
34
includes a cylinder block
98
(
FIG. 4
) defining four cylinder bores in which pistons reciprocate. At least one cylinder head member is affixed to the upper end of the cylinder block
98
to close respective upper ends of the cylinder bores and defines combustion chambers with the cylinder bores and the pistons. Separate cylinder head members for each cylinder bore also can be used.
A crankcase member
99
(
FIGS. 4-6
) also is affixed to the lower end of the cylinder block
98
to close the respective lower ends of the cylinder bores and to define a crankcase chamber with the cylinder block
98
. The crankshaft
88
is journaled for rotation on bearings within the crankcase chamber and is rotatably connected to the pistons through connecting rods. The cylinder block
98
, the cylinder head and the crankcase member
99
preferably are made of aluminum alloy and together define an engine body
100
. The illustrated engine
34
, however, merely exemplifies one type of engine. Other types of engines having other number of cylinders, other cylinder arrangements (V-type and W-type) and operating on other combustion principles (e.g., two-cycle, rotary, diesel) all are applicable.
With referende to
FIGS. 5-7
, the reduction and output gears
91
,
92
preferably are positioned within a gear chamber
101
defined within a gear housing
102
which is affixed at a rear end of the crankcase member
99
. The intermediate shaft
90
extends generally horizontally through an opening
103
of the gear housing
102
toward the impeller shaft
87
. A seal member can provide a water-tight seal at the opening
103
. An external portion of the intermediate shaft
90
is journaled on bearings
104
mounted to the engine body
100
.
Engine mounts
105
(
FIGS. 3 and 4
) extend from both sides of the engine body
100
. The engine mounts
105
preferably include resilient portions made of, for example, a rubber material. The engine body
100
is mounted on the lower hull section
38
(or possibly on the hull liner) by the engine mounts
105
so that vibration of the engine body
100
is inhibited from conducting to the hull section
38
.
The engine
34
comprises an air induction system, a fuel supply system, an ignition system and an exhaust system, although other systems can optionally be provided. The air induction system is arranged to introduce air to the combustion chambers. Throttle valves preferably are provided to regulate the air or measure an amount of the air passing through the induction system.
In the illustrated embodiment, a plenum chamber assembly
108
(
FIGS. 3 and 4
) is provided to collect and filter induction air and to reduce intake noise. The plenum chamber assembly
108
preferably is mounted on the engine body
100
. Throttle bodies journaling the throttle valves for pivotal movement preferably are housed within the plenum chamber assembly
108
.
The fuel supply system is arranged to supply fuel to the combustion chambers within the engine body
100
. A port injected or indirect fuel injection device preferably is employed to spray the fuel into intake ports of the induction system under control of a control device such as, for example, an ECU (Electronic Control Unit) (not shown). Preferably, initiation timing and duration of the injections are controlled by the ECU. A direct fuel injection system that sprays fuel directly into the combustion chambers of course can replace the port injection device. Moreover, other fuel charge forming devices such as, for example, a carburetor assembly can be used instead of the fuel injection system.
The ignition system is arranged to fire air/fuel charges in the combustion chambers at controlled ignition timings. The ECU preferably controls the ignition timings also.
The exhaust system is arranged to guide exhaust gases from the combustion chambers to a location outside of the watercraft
30
. In the illustrated embodiment, the exhaust gases are discharged to the tunnel
82
through a plurality of exhaust manifolds, conduits and/or devices
112
-
124
, described in greater detail below.
A large part of the respective constructions and arrangements of the foregoing systems are well known to those of ordinary skill in the art. A co-pending U.S. patent application filed Jan. 17, 2001, titled ENGINE FOR WATERCRAFT, which serial number is Ser. No. 09/765,052, and also a co-pending application filed Jul. 31, 2001, titled FOUR-CYCLE ENGINE, disclose exemplary constructions and arrangements, the entire contents of which are hereby expressly incorporated by reference.
As shown in
FIG. 3
, first and second exhaust manifolds
112
,
114
depend from the cylinder head member at a starboard side surface thereof. The exhaust manifolds
112
,
114
define outer exhaust passages that are coupled with inner exhaust passages defined within the cylinder head member to collect exhaust gases from the respective inner exhaust passages. More specifically, the first exhaust manifold
112
has a pair of end portions spaced apart from each other with a length that is equal to a distance between the forward-most inner exhaust passage and the rear-most inner exhaust passage. The end portions are connected with the forward-most and rear-most exhaust passages. The second exhaust manifold
114
also has a pair of end portions spaced apart from each other with a length that is equal to a distance between the other two or in-between exhaust passages. The end portions of the second exhaust manifold
114
are connected with the in-between exhaust passages. The exhaust manifolds
112
,
114
extend slightly downwardly. Respective downstream ends of the first and second exhaust manifolds exist closely with one another and are coupled with an upstream end of a first unitary exhaust conduit
116
.
The first unitary conduit
116
extends further downwardly and then upwardly as it extends forwardly and in a downstream direction of the exhaust system. A downstream end of the first unitary conduit
116
is coupled with an upstream end of a second unitary exhaust conduit
118
. The second unitary conduit
118
extends further upwardly and then transversely to end in front of the engine body
100
. As shown in
FIG. 4
, the second unitary conduit
118
is coupled with an exhaust pipe
120
on the front side of the engine body
100
. The coupled portions thereof preferably are supported by a front surface of the engine body
100
. The exhaust pipe
120
extends rearwardly along a side surface of the engine body
100
on the port side and then is connected to an exhaust silencer or water-lock
122
at a forward surface of the exhaust silencer
122
.
With reference to
FIG. 2
, the exhaust silencer
122
preferably is placed at a location generally behind the engine body
100
but in a half space on the port side and is secured to the lower hull section
38
(or possibly to a hull liner). A discharge pipe
124
extends from a top surface of the exhaust silencer
122
and transversely across the center plane CP to the other half space on the starboard side. The discharge pipe
124
then extends rearwardly and opens at the tunnel
82
and thus to the exterior of the watercraft
30
in a submerged position. The exhaust silencer
122
has one or more expansion chambers to reduce exhaust noise and also to inhibit water in the discharge pipe
124
from entering the exhaust pipe
120
when the watercraft
30
capsizes because of its construction and arrangement as is well known.
As shown in
FIG. 3
, the exhaust system preferably is provided with a secondary air delivery device
126
that can purify the exhaust gases by oxidation reaction with oxygen that is supplied to the exhaust system through the device
126
.
The watercraft
30
preferably employs a cooling system for the engine
34
and the exhaust system. Preferably, the cooling system is an open-loop type and includes a water pump and a plurality of water jackets and/or conduits. In the illustrated embodiment, the jet pump assembly
80
is used as the water pump with a portion of the water pressurized by the impeller being drawn off for the cooling system, as known in the art.
The engine body
100
and the respective exhaust manifolds and conduits
112
-
120
preferably define the water jackets. Both portions of the water to the water jackets of the engine body
100
and to the water jackets of the exhaust system can flow through either common channels or separate channels formed within one or more exhaust manifolds and conduits
112
-
120
or external water pipes. The illustrated exhaust manifolds and conduits
112
-
120
preferably are formed as dual passage structures in general.
With primary reference to
FIGS. 6-11
and continued reference to
FIGS. 3-5
, a preferred construction and arrangement of a lubrication system
130
that includes the oil pump unit
32
is described below.
FIG. 8
illustrates a block diagram schematically showing the lubrication system
130
. The lubrication system
130
is employed for delivering lubricant oil to engine portions
132
that benefit from lubrication and for collecting the oil for recirculation. The engine portions
132
includes, for example, coupling portions of the crankshaft
88
, pistons, connecting rods and respective bearings as is well known to those of ordinary skill in the art. The illustrated lubrication system
130
is a closed-loop, dry-sump type, although other types can of course be applied.
The lubrication system
130
preferably comprises an oil tank or primary oil reservoir
134
and an oil cap or temporary oil reservoir
138
other than the oil pump unit
32
. As shown in
FIGS. 3-5
, the oil tank
134
preferably is configured as a rectangular parallelepiped reservoir for storing lubricant oil. The oil tank
134
is disposed, for example, on a rear side of the engine body
100
and is mounted on the engine body
100
or directly affixed to the lower hull section
38
. The oil cap
138
is formed at a bottom of the crankcase chamber that is defined by the crankcase member
99
. That is, the oil cap
138
is located under the engine portions
132
in the engine body
100
.
As schematically shown in
FIG. 6
, the oil pump unit
32
is mounted on the gear housing
102
adjacent to the bearings
104
on which the intermediate shaft
90
of the coupling member
89
is journaled. The oil pump unit
32
comprises a feed pump assembly
142
and a scavenge pump assembly
144
.
With reference to
FIG. 8
, the oil pump unit
32
preferably has two inlet openings
148
,
150
and two outlet openings
152
,
154
. The inlet opening
148
is connected with the oil tank
134
through a supply passage
158
, while the inlet opening
150
is connected with the oil cap
138
through an external scavenge passage
160
. The outlet opening
152
in turn is connected with the engine portions
132
through one or more delivery passages
162
, while the outlet opening
154
is connected with the oil tank
134
through an external return passage
164
.
Internally, the feed pump assembly
142
preferably has an inlet port
168
connected with the inlet opening
148
and an outlet port
170
connected with the outlet opening
152
. The scavenge pump assembly
144
in turn advantageously has a pair of inlet ports
174
,
176
and a pair of outlet ports
178
,
180
. The inlet port
174
is connected with the inlet opening
150
through an internal scavenge passage
184
, while the inlet port
176
also is connected with the inlet opening
150
through a branch passage
186
and then through the scavenge passage
184
. The outlet port
178
in turn is connected with the outlet opening
154
through an internal return passage
188
, while the outlet port
180
also is connected with the outlet opening
154
through a branch passage
190
and then through the return passage
188
.
With primary reference to
FIGS. 6 and 8
, the oil pump unit
32
preferably comprises a housing
194
, a pump shaft
196
, inner and outer feed pump rotors
198
,
200
, and inner and outer scavenge pump rotors
202
,
204
. The housing
194
preferably comprises first, second and third housing members
206
,
208
,
210
which are coupled together by through bolts.
FIG. 10
shows bolt holes
212
for the bolts. Preferably, the first or front housing member
206
has flanges (not shown) to be affixed to the gear housing
102
by bolts. The second or middle housing member
208
forms a feed pump space
214
and a scavenge pump space
216
. The inner and outer feed pump rotors
198
,
200
have respective end portions axially spaced apart from each other and are disposed within the feed pump space
214
, while the inner and outer scavenge pump rotors
202
,
204
also have end portions axially spaced apart from each other and are disposed within the scavenge pump space
216
. The pump shaft
196
extends generally horizontally within the housing
194
in parallel to the intermediate shaft
90
and is journaled on the front and rear housing members
206
,
210
. The pump shaft
196
preferably has a uniform diameter throughout.
The pump shaft
196
is driven by the crankshaft
88
. In the illustrated embodiment, a pump gear
220
meshes with the output gear
92
of the crankshaft
88
on an opposite side to the reduction gear
91
, and a pump gear shaft
222
of the pump gear
220
is coupled with the pump shaft
196
. An axis
223
of the pump gear shaft
222
is coincident with an axis of the pump shaft
196
.
The gear housing
102
has a cylindrical bearing portion
224
in which the pump gear shaft
222
extends to be journaled thereon. The pump gear shaft
222
has a coupling recess
226
at a rear end thereof, while the pump shaft
196
has a coupling projection
228
that fits in the coupling recess
226
. The pump shaft
196
thus rotates together with the pump gear shaft
222
which is driven by the crankshaft
88
through the meshed output gear
92
and the pump gear
220
.
As shown in
FIGS. 6 and 7
, the output gear
92
, the reduction gear
91
and the pump gear
220
together form a gear train
230
. Because a diameter of the pump gear
220
is greater than the diameter of the output gear
92
and is generally equal to the diameter of the reduction gear
91
, the pump gear shaft
222
and the pump shaft
196
rotates slower than the crankshaft
88
and can be approximately the same speed as the intermediate shaft
90
.
With reference to
FIGS. 9 and 10
, the pump shaft
196
preferably is journaled on bearing portions
234
,
236
,
238
of the front, middle, and rear housing members
206
,
208
,
210
, respectively. The illustrated feed and scavenge pump spaces
214
,
216
are formed in series with each other on the pump shaft
196
. In other words, the scavenge pump space
216
is spaced apart from the feed pump space
214
along the axis
223
of the pump shaft
196
. Preferably, the feed pump space
214
is disposed closer to the gear housing
102
, i.e., the engine body
100
. A seal member
240
is provided around the pump shaft
196
between the feed and scavenge pump spaces
214
,
216
to liquid-tightly separate both the spaces
214
,
216
.
The inner and outer rotors
198
,
200
together define the feed pump assembly
142
with the pump shaft
196
and the middle housing member
208
, while inner and outer rotors
202
,
204
together define the scavenge pump assembly
144
also with the pump shaft
196
and the middle housing member
208
. In the illustrated embodiment, both the feed and scavenge pump assemblies
142
,
144
have a typical trochoid pump construction.
As schematically shown in
FIG. 11
, the respective inner rotors
198
,
202
preferably have four teeth and affixed to the pump shaft
196
to rotate together with the pump shaft
196
. As shown in
FIG. 9
, the pump shaft
196
defines key ways
248
,
250
positioned at the feed and scavenge pump spaces
214
,
216
. Keys
252
,
254
coupled with the pump shaft
196
engage with the respective key ways
248
,
250
to rotate the inner rotors
198
,
202
with the pump shaft
196
. The outer rotors
200
,
204
are disposed around the inner rotors
198
,
202
. The respective outer rotors
200
,
204
define five recesses in which the teeth of the inner rotors
198
,
202
are engageable.
FIG. 10
shows an outer surface of the outer rotors
200
,
204
with a phantom line
258
. As shown in
FIGS. 10 and 11
, the pump shaft
196
is slightly offset from a center axis of the outer rotors
200
,
204
.
Because of the configurations and arrangements of the inner and outer rotors
198
,
200
,
202
,
204
, the outer rotors
200
,
204
are rotated by the inner rotors
198
,
202
with a certain lost motion relative to the inner rotors
198
,
202
. As a result, pumping chambers
260
,
262
, which volumes vary with the rotations of the pump shaft
196
, are formed between the inner and outer rotors
198
,
200
and also between the inner and outer rotors
202
,
204
.
With reference to
FIG. 9
, the inlet and outlet ports
168
,
170
of the feed pump assembly
142
preferably are formed in the front housing member
206
on one side, i.e., on a front side, of the feed pump assembly
142
. In other words, the inlet and outlet ports
168
,
170
are defined next to one end, i.e., front end, of the inner and outer rotors
198
,
200
. Similarly but on both sides of the scavenge pump assembly
144
, the inlet and outlet ports
174
,
176
,
178
,
180
are formed. That is, the inlet and outlet ports
174
,
178
of the scavenge pump assembly
144
preferably are formed in the rear housing member
210
on one side, i.e., on a rear side, of the scavenge pump assembly
142
, while the inlet and outlet ports
176
,
180
of the scavenge pump assembly
144
are formed in the middle housing member
208
on the other side, i.e., preferably on a front side, of the scavenge pump assembly
142
. In other words, the inlet and outlet ports
174
,
178
are defined next to one end, i.e., rear end, of the inner and outer rotors
202
,
204
, while the inlet and outlet ports
176
,
180
are defined next to the other end, i.e., front end, of the inner and outer rotors
202
,
204
.
The inlet and outlet ports
168
,
170
of the feed pump assembly
142
are configured as generally the same arcs and do not communicate with each other. When one of the pumping chambers
260
of the feed pump assembly
142
communicates with the inlet port
168
and moves for a while, the volume of the pumping chamber
260
increases and hence lubricant oil is drawn into the pumping chamber
260
through the inlet port
168
. Afterwards, when the pumping chamber
260
communicates with the outlet port
170
and moves for a while, the volume of the pumping chamber
260
decreases and hence lubricant oil is pushed out from the pumping chamber
260
through the outlet port
170
. Same situations occur with other pumping chambers
260
continuously with the rotation of the pump shaft
196
.
In contrast, the respective inlet and outlet ports
174
,
176
,
178
,
180
are configured as generally the same arcs. The inlet and outlet ports
174
,
178
do not communicate with each other. Similarly, the inlet and outlet ports
176
,
180
do not communicate with each other. When one of the pumping chambers
262
of the scavenge pump assembly
144
communicates with both the inlet ports
176
,
174
and moves for a while, the volume of the pumping chamber
262
increases and hence lubricant oil is drawn into the pumping chamber
262
through the inlet ports
174
,
176
. Afterwards, when the pumping chamber
262
communicates with both the outlet ports
178
,
180
and moves for a while, the volume of the pumping chamber
262
decreases and hence lubricant oil is pushed out from the pumping chamber
262
through the outlet ports
178
,
180
. The same situation occurs with the other pumping chambers
262
continuously with the rotation of the pump shaft
196
.
With reference to
FIG. 9
, the inlet port
168
of the feed pump assembly
142
is connected with the inlet opening
148
without any substantial interconnecting passage. The outlet port
170
of the feed pump assembly
142
also is connected with the outlet opening
152
without any substantial interconnecting passage. The internal scavenge passage
184
that connects the inlet port
174
with the inlet opening
150
is formed within the front, middle, and rear housing members
206
,
208
,
210
to extend generally in parallel to the axis of the pump shaft
196
out of the feed and scavenge pump assemblies
142
,
144
. The branch passage
186
is defined within the middle housing member
176
to branch off from the internal scavenge passage
184
.
The illustrated branch passage
186
can be formed by drilling from outside of the housing member
208
so that an axis of the branch passage
186
extends generally normal to an axis of the internal scavenge passage
184
. A closure plug
270
closes an opening
272
made in the drilling process. The inlet opening
150
thus is positioned oppositely from the pump shaft
196
relative to the inlet opening
148
on the same side of the housing
194
where the housing
194
is mounted on the gear housing
102
. This is advantageous because the external conduits or pipes
158
,
162
can be as short as possible.
The internal return passage
188
that connects the outlet port
178
with the outlet opening
154
in turn is formed within the front, middle, and rear housing members
206
,
208
,
210
to extend generally parallel to the axis of the pump shaft
196
out of the feed and scavenge pump assemblies
142
,
144
. The branch passage
190
is defined within the middle housing member
176
to merge with the internal return passage
188
. The illustrated branch passage
190
also can be formed by drilling from outside of the housing member
208
so that an axis of the branch passage
190
extends generally normal to an axis of the internal return passage
188
. A closure plug
274
closes an opening
276
made in the drilling process.
As shown in
FIG. 10
, the respective branch passages
186
,
190
preferably cross one another with an angle such as, for example, approximately 60 degrees. The outlet opening
154
thus is positioned oppositely from the pump shaft
196
relative to the outlet opening
170
on the same side of the housing
194
where the housing
194
is mounted on the gear housing
102
as well as the inlet openings
148
,
150
. That is, all of the inlet and out let openings
148
,
150
,
152
,
154
are formed between the gear housing
102
and the front housing member
206
, i.e., the pump housing
194
. This is also advantageous because the external conduits or pipes
160
,
164
can be as short as possible.
Either the feed or scavenge pump assembly
142
,
144
can be positioned adjacent to the gear housing
102
. In the illustrated embodiment, the feed pump assembly
142
is advantageously located next to the gear housing
102
because, in general, the feed pump assembly
142
is more important than the scavenge pump assembly
144
. That is, a closer location does not need substantial passages that increase flow resistance than the other location and hence the feed pump assembly
142
in this location can be more powerful than the scavenge pump assembly
144
.
As described above, in the illustrated embodiment, the scavenge pump assembly
144
has two pairs of inlet and outlet ports
174
,
176
,
178
,
180
on both sides thereof. Because of this arrangement, the lubricant oil can immediately enter the pumping chambers
262
and expand with less delay during filling the entire volume of the respective chambers
262
. Accordingly, a relatively large volume of scavenge pump assembly
144
can be applicable. As shown in
FIG. 9
, the illustrated scavenge pump assembly
144
thus is configured larger than the feed pump assembly
142
. That is, a length L
1
between both the ends of the inner and outer rotors
202
,
204
of the scavenge pump assembly
144
is longer than a length L
2
between both the ends of the inner and outer rotors
198
,
200
. Of course, the scavenge and feed pump spaces
216
,
214
have generally the same lengths L
1
, L
2
, respectively, to house them therein. Preferably, the length L
1
is one and a half times as long as the length L
2
. Because of this dimensional relationship, the volume of the pumping chambers
262
of the scavenge pump assembly
144
is greater than the volume of the pumping chambers
260
of the feed pump assembly
142
. Incidentally, the bearing portion
236
of the in-between housing member
208
preferably has an axial length L
3
that is shorter than the length L
1
and longer than the length L
2
.
As the oil pump unit
32
operates along with the operation of the engine
34
, the lubricant oil in the oil tank
134
flows through the supply passage
158
and is drawn into the pumping chambers
260
of the feed pump assembly
142
through the inlet opening
148
of the oil pump unit
32
and the inlet port
168
of the feed pump assembly
142
. The feed pump assembly
142
feeds the lubricant oil from the pumping chambers
260
to the engine portions
132
through the outlet port
170
of the feed pump assembly
142
and then the outlet opening
152
of the oil pump unit
32
and further through one or more delivery passages
162
. The lubricant oil lubricates the engine portions
132
and falls down to the oil cap
138
by its own weight. The lubricant oil in the oil cap
138
then flows through the external scavenge passage
160
and is drawn to the oil pump unit
32
at another inlet opening
150
. The lubricant oil then proceeds through the internal scavenge passage
184
to the inlet port
174
of the scavenge pump assembly
144
as indicated by an arrow A of FIG.
9
and then is drawn into the pumping chambers
262
.
Simultaneously, a portion of the oil is branched off to the inlet port
176
through the branch passage
186
as indicated by an arrow B of FIG.
9
and is drawn into the pumping chambers
262
. The scavenge pump assembly
144
pressurizes the lubricant so as to flow toward the oil tank
134
from the outlet ports
178
,
180
. The oil in the pumping chambers
262
flows out through both the outlet ports
178
,
180
as indicated by arrows C and D of FIG.
9
. The lubricant oil from the outlet port
178
proceeds through the internal return passage
188
and the oil from the outlet port
180
goes through the branch passage
190
and then merges with the oil proceeding through the internal return passage
188
. The lubricant oil that has passed through the internal return passage
188
flows out to the external return passage
164
from the outlet opening
154
. This circulation of the lubricant oil continues as the engine
34
operates.
During the operation of the oil pump unit
32
, the rotational speed of the pump shaft
196
varies in response to changes in engine speed, i.e., the rotational speed of the crankshaft
88
. The inner and outer rotors
202
,
204
of the scavenge pump assembly
144
, which are positioned farther from the inlet and outlet openings
150
,
154
in this embodiment, also rotate with the rotation of the pump shaft
196
. Because it has a larger volume, the scavenge pump assembly
144
provides a desirable flow rate of the return oil to the oil tank
134
. Since the pairs of inlet and outlet ports
174
,
176
,
178
,
180
on both the sides of the scavenge pump assembly
144
can have the oil immediately expand to fill the pumping chambers
262
even under a high speed rotational condition of the pump shaft
196
, the pump unit
32
provides enhanced oil flow over a larger range of pump shaft
196
speeds. It should be noted that the respective locations of the feed and scavenge pump assemblies within the pump unit are interchangeable with each other.
The outlet ports
178
,
180
of the pump assembly, which is the scavenge pump assembly
144
in the embodiment, are not necessarily a pair on both the sides.
FIG. 12
illustrates another embodiment of the oil pump unit
32
. The members and components, which have already been described, are assigned with the same reference numerals and will not be described repeatedly.
In this embodiment, the scavenge pump assembly
144
has only one outlet port
178
, although both the inlet ports
174
,
176
still are provided. This arrangement advantageously expedites the filling of the pumping chambers
262
with lubricant because the lubricant flow out from the chambers
262
is more restricted than the lubricant flow into the chambers
262
. It should be noted again that the respective locations of the feed and scavenge pump assemblies within the pump unit are interchangeable with each other in this embodiment. Also, the outlet port
178
can be omitted instead of the outlet port
180
. In this alternative, the branch passage
190
of course is a portion of the internal return passage
188
.
With reference to
FIG. 13
, the oil pump units
32
illustrated in
FIGS. 8 and 12
, can have a pressure relief construction
280
disposed on a projected portion
282
of the gear housing
102
where the outlet opening
152
of the feed pump assembly
142
is formed. The outlet opening
152
in part is connected with the gear chamber
101
through an aperture
284
defined at the projected portion
282
. The aperture
284
comprises a small diameter portion
285
and a large diameter portion
286
that is positioned closer to the gear chamber
101
than the small diameter portion. In other words, the small diameter portion
285
communicates with the outlet opening
152
, while the large diameter portion
286
communicates with the gear chamber
101
. A relief valve
287
is slideably supported in the small diameter portion
285
. The relief valve
287
defines four through-holes
288
that can open to the large diameter portion
286
when the relief valve
287
moves toward the large diameter portion
286
, i.e., to an open position. A coil spring
290
is disposed around a tip portion of the relief valve
287
within the large diameter portion
286
of the aperture
284
. An end of the spring
290
abuts on a flange portion
292
of the relief valve
287
. Another end of the spring
290
abuts on a retainer assembly
294
that is affixed to the projected portion
282
by a bolt
296
. The spring
290
thus normally urges the relief valve
287
toward the outlet opening
152
to close the through-holes
288
, i.e., to a closed position. The retainer assembly
294
defines a space through which the large diameter portion
286
communicates with the gear chamber
101
.
In the event such that the pressure within the feed pump assembly
142
abnormally increases, the relief valve
287
moves to the open position from the closed position against the bias force of the spring
290
to relieve the pressure toward the gear chamber
101
. As such, a certain amount of the lubricant oil within the feed pump assembly
142
flows into the gear chamber
101
. Afterwards, the spring
290
again biases the relief valve
287
to set it back to the closed position. The gear chamber
101
contains some of the lubricant oil to lubricate the gear train
230
. The lubricant oil entering the chamber
101
thus merges with this lubricant oil and then moves to the oil cap
138
anyway.
It should be noted that the scavenge pump assembly instead can have the relief valve at its outlet opening, or both the feed and scavenge pump assemblies can have the relief valve.
Of course, the foregoing description is that of a preferred construction having certain features, aspects and advantages in accordance with the present invention. Various changes and modifications may be made to the above-described arrangements without departing from the spirit and scope of the invention, as defined by the appended claims.
Claims
- 1. An oil pump unit for an internal combustion engine comprising a housing, a shaft extending within the housing and journaled thereon for rotation about a shaft axis, the shaft being driven by the engine, a first pump assembly disposed on the shaft to be driven by the shaft, and a second pump assembly disposed on the shaft in series with the first pump assembly to be driven by the shaft, the first and second pump assemblies each defining end portions spaced apart from each other along the shaft axis, the housing defining a first inlet port and at least one outlet port at one of the end portions of the first pump assembly, a second inlet port and a second outlet port at one of the end portions of the second pump assembly, and at least a third inlet port at the other end portion of the second pump assembly.
- 2. The oil pump unit as set forth in claim 1, wherein the shaft is coupled with an output shaft of the engine at a first location on one side of the housing, and the first pump assembly is disposed next to the first location.
- 3. The oil pump unit as set forth in claim 1, wherein the housing further defines an inlet passage coupling the second and third inlet ports with each other, and a portion of the inlet passage communicating with the second inlet port is positioned between the first and second pump assemblies.
- 4. The oil pump unit as set forth in claim 3, wherein the housing still further defines an inlet opening communicating with the inlet passage.
- 5. The oil pump unit as set forth in claim 4, wherein the inlet opening is formed at a side surface of the housing, and the side surface is positioned closer to the first pump assembly than the second pump assembly.
- 6. The oil pump unit as set forth in claim 1, wherein the second pump assembly comprises an inner rotor affixed to the shaft to rotate with the shaft and an outer rotor disposed around the inner rotor to be rotated by the inner rotor, the inner and outer rotors together defining at least one pumping chamber, a volume of the pumping chamber varying with rotation of the inner and outer rotors, the second inlet and outlet ports selectively communicating with the pumping chamber with the rotation of the inner and outer rotors.
- 7. The oil pump unit as set forth in claim 1, wherein a length between the end portions of the second pump assembly is longer than a length between the end portions of the first pump assembly.
- 8. The oil pump unit as set forth in claim 1, wherein the second pump assembly defines a scavenge pump assembly arranged to collect lubricant oil that has circulated within the engine.
- 9. The oil pump unit as set forth in claim 8, wherein the first pump assembly defines a feed pump arranged to feed the lubricant oil to the engine.
- 10. The oil pump unit as set forth in claim 1, wherein the housing defines a third outlet port at the other end portion of the second pump assembly.
- 11. The oil pump unit as set forth in claim 10, wherein the third inlet and outlet ports selectively communicate with the pumping chamber during rotation of the inner and outer rotors.
- 12. The oil pump unit as set forth in claim 10, wherein the housing defines an outlet passage coupling the second and third outlet ports with each other, and a portion of the outlet passage communicating with the first outlet port is positioned between the first and second pump assemblies.
- 13. The oil pump unit as set forth in claim 12, wherein the housing defines an outlet opening communicating with the outlet passage.
- 14. The oil pump unit as set forth in claim 13, wherein the outlet opening is formed at a side surface of the housing, and the side surface is positioned closer to the first pump assembly than the second pump assembly.
- 15. The oil pump unit as set forth in claim 1, wherein the engine operates on a four-cycle combustion principle.
- 16. The oil pump unit as set forth in claim 1, wherein the engine powers a marine propulsion device.
- 17. A lubrication system for an internal combustion engine comprising a first oil reservoir arranged to contain lubricant oil, a second oil reservoir arranged to receive the lubricant oil that has lubricated portions of the engine, and an oil pump unit arranged to supply the lubricant oil within the first oil reservoir to the portions of the engine and to return the lubricant oil within the second oil reservoir to the first oil reservoir, the oil pump unit comprising a housing, a shaft extending within the housing and journaled thereon for rotation about a shaft axis, the shaft being driven by the engine, a feed pump assembly disposed on the shaft to be driven by the shaft, and a scavenge pump assembly disposed on the shaft in series with the feed pump assembly to be driven by the shaft, the feed and scavenge pump assemblies each defining end portions spaced apart from each other along the shaft axis, the housing defining a first inlet port and a first outlet port at one of the end portions of the feed pump assembly, a second inlet port and a second outlet port at one of the end portions of the scavenge pump assembly, and at least a third inlet port at the other end portion of the scavenge pump assembly.
- 18. The lubrication system as set forth in claim 17, wherein the first inlet port and the second outlet port are connected to the first oil reservoir, the first outlet port is connected to the portions of the engine, and the second and third inlet ports are connected to the second oil reservoir.
- 19. The lubrication system as set forth in claim 18, wherein the first outlet port includes a relief valve arranged to allow the lubricant oil in the feed pump assembly to move toward the second oil reservoir when a pressure in the feed pump assembly is greater than a preset pressure.
- 20. The lubrication system as set forth in claim 17, wherein the shaft is coupled with an output shaft of the engine at a location on one side of the housing, the feed pump assembly is disposed next to the location to extend between the location and the scavenge pump assembly.
- 21. The lubrication system as set forth in claim 20, wherein the housing an inlet passage coupling the first and second inlet ports with each other, and a portion of the inlet passage communicating with the first inlet port is positioned between the feed and scavenge pump assemblies.
- 22. The lubrication system as set forth in claim 17, wherein the scavenge pump assembly comprises an inner rotor affixed to the shaft to rotate with the shaft, an outer rotor disposed around the inner rotor to be rotated by the inner rotor, the inner and outer rotors together define at least one pumping chamber, a volume of the pumping chamber varying with rotation of the inner and outer rotors, the second inlet and outlet ports selectively communicating with the pumping chamber with the rotation of the inner and outer rotors.
- 23. The lubrication system as set forth in claim 17, wherein the housing defines a third outlet port at the other end portion of the scavenge pump assembly.
- 24. The lubrication system as set forth in claim 23, wherein the third inlet and outlet ports selectively communicate with the pumping chamber during the rotation of the inner and outer rotors.
- 25. The lubrication system as set forth in claim 17, wherein the first oil reservoir is a primary reservoir of the lubrication system and the second reservoir is a temporary reservoir in the lubrication system.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2000-175655 |
Jun 2000 |
JP |
|
US Referenced Citations (7)