Information
-
Patent Grant
-
6742491
-
Patent Number
6,742,491
-
Date Filed
Tuesday, December 17, 200221 years ago
-
Date Issued
Tuesday, June 1, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Yuen; Henry C.
- Benton; Jason
Agents
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
The present invention provides a lubrication system for small internal combustion engines. In a first aspect, a helical oil pump includes a helical insert which is disposed within a bore in the engine camshaft and is rotationally fixed with respect to the crankcase. During running of the engine, rotation of the camshaft draws oil from the oil sump upwardly through the bore in the camshaft and around the helical insert to provide lubrication oil directly to the upper camshaft bearing and to the upper crankshaft bearing. In another aspect, an impeller oil pump includes a pump chamber defined between the camshaft gear and a pump body which is rotationally fixed with respect to the crankcase and in communication with the oil sump. An impeller assembly mounted on the camshaft is disposed within the pump chamber, and draws oil from the oil sump into the pump chamber. The oil is forced outwardly of the pump chamber through an opening in the camshaft gear in the form of a stream of pressurized oil which is directed toward different locations within the crankcase as the camshaft gear rotates with the camshaft.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to lubrication systems for small internal combustion engines of the type used with lawnmowers, lawn and garden tractors, other small implements, or sport vehicles.
2. Description of the Related Art
Small internal combustion engines typically include a crankcase with an oil sump containing an amount of oil which is conveyed to various lubrication points within the engine to lubricate the moving parts within the engine.
One known lubrication arrangement employs an oil dipper or slinger which is mounted to the end of the connecting rod or to the engine crankshaft which, during the rapid rotation of the engine crankshaft during running of the engine, contacts the oil in the oil sump to agitate and splash the oil into a mist within the engine crankcase. The oil mist contacts and lubricates the various moving parts within the crankcase. Additionally, pressure pulses within the crankcase which are created by the reciprocation of one or more of the engine pistons may be employed to convey the oil mist from the crankcase to other portions of the engine which include moving parts, such as the cylinder head. The foregoing lubrication arrangement is typically referred to as “splash lubrication”, and usually is most useful in small, single cylinder engines.
A disadvantage of splash lubrication is that same does not provide pressurized, liquid oil directly to the various lubrication points within the engine, such as shaft bearings. Additionally, splash lubrication systems can be difficult to design which are effective for use in twin cylinder engines and for some vertical crankshaft engines.
In another lubrication arrangement, a gerotor pump, or another suitable type of oil pump, is driven from the crankshaft or camshaft within the engine crankcase. The oil pump is operable to draw oil from the oil sump and force the oil under pressure through passages within the crankshaft and/or camshaft or other oil galleries in the engine housing in order to convey the oil to specific lubrication points within the engine, such as shaft bearings or contact points within the valve train.
A disadvantage with existing lubrications systems which include gerotor or other types of oil pumps is that same typically include a number of moving parts, may be difficult to manufacture, and may require the machining of numerous oil passages in the engine shafts and/or engine housing to convey the pressurized oil to the various lubrication points.
In another arrangement, often referring to as “dry sump” lubrication, the crankcase includes a minimal amount of oil, wherein most of the engine oil is stored in an oil reservoir which is separate from the crankcase. A lubrication pump is driven by the engine, and pumps oil from the oil reservoir through passages in the crankshaft and/or camshaft or other galleries in the engine housing to lubricate the moving parts of the engine. Thereafter, the oil drips back into the crankcase. A scavenge pump, also driven by the engine, pumps the oil within the crankcase back into the oil reservoir.
A disadvantage with dry sump lubrication systems is that same require two oil pumps and a separate oil reservoir, which increases the cost and complexity of such systems.
Additionally, other lubrication systems for small internal combustion engines may include various combinations of some or all of the components of the foregoing lubrication arrangements.
What is needed is a lubrication system for small internal combustion engines which is an improvement over the foregoing.
SUMMARY OF THE INVENTION
The present invention provides a lubrication system for small internal combustion engines. In a first aspect of the present invention, a helical oil pump includes a helical insert disposed within a bore in the engine camshaft. The camshaft is rotatably driven from the crankshaft, while the helical insert is rotationally fixed with respect to the crankcase. The lower ends of the camshaft and the helical insert are in communication with the oil sump of the crankcase and, during running of the engine, rotation of the camshaft draws oil from the oil sump upwardly through the bore in the camshaft and around the helical insert to provide lubrication oil directly to the upper camshaft bearing and thence to the upper crankshaft bearing through a passage in the crankcase.
In another aspect of the present invention, an impeller oil pump includes a pump chamber defined between the camshaft gear and a pump body which is rotationally fixed with respect to the crankcase and in communication with the oil sump. An impeller assembly mounted on the camshaft is disposed within the pump chamber such that, upon rotation of the camshaft, the impeller assembly draws oil from the oil sump into the pump chamber. The oil is forced outwardly of the pump chamber through an opening in the camshaft gear in the form of a stream of pressurized oil which is directed toward different locations within the crankcase as the camshaft gear rotates with the camshaft.
Advantageously, the helical oil pump of the present lubrication system provides pressurized lubrication oil directly to the upper camshaft bearing and to the upper crankshaft bearing to lubricate same. Additionally, the impeller oil pump supplies a stream of pressurized oil which is directed toward a plurality of locations within the crankcase as the cam gear rotates, thereby lubricating the crank pin, drive train components, and other moving parts within the crankcase with a stream of pressurized oil. Further, the oil pump is effective to circulate a large volume of oil continuously within the crankcase, such that the stream of pressurized oil which contacts the crankcase walls helps to cool the crankcase and reduce the operating temperature of the engine.
In one form thereof, the present invention provides an internal combustion engine, including a crankcase containing an oil sump therein; a crankshaft rotatably supported within the crankcase; a second shaft rotatably supported within the crankcase in timed driven relationship with the crankshaft, the second shaft disposed vertically and including a bore therethrough which communicates between upper and lower ends of the second shaft; and a helical insert disposed within the bore, the helical insert rotationally fixed with respect to the crankcase, the lower end of the second shaft and the helical insert in communication with the oil sump wherein rotation of the second shaft about the helical insert draws oil from the oil sump upwardly through the bore.
In another form thereof, the present invention provides an internal combustion engine, including a crankcase containing an oil sump therein; a shaft rotatably supported within the crankcase; a plate mounted on the shaft and rotatable therewith, the plate having at least one opening therethrough; a pump body fixed with respect to the crankcase and in fluid communication with the oil sump, the pump body and the plate defining a pump chamber therebetween; and an pump assembly disposed within the pump chamber and mounted on the shaft for rotation therewith; whereby rotation of the shaft and the pump assembly draws oil from the oil sump into the pump chamber and forces oil outwardly of the pump chamber through the opening in the plate.
In a further form thereof, the present invention provides an internal combustion engine, including a crankcase containing an oil sump therein; a shaft rotatably supported within the crankcase, the shaft including a bore therethrough which communicates between upper and lower ends of the shaft; a helical insert disposed within the bore, the helical insert rotationally fixed with respect to the crankcase, the lower end of the second shaft and the helical insert in communication with the oil sump; a plate mounted on the shaft and rotatable therewith, the plate having at least one opening therethrough; a pump body fixed with respect to the crankcase and in fluid communication with the oil sump, the pump body and the plate defining a pump chamber therebetween; and a pump assembly disposed within the pump chamber and mounted on the shaft for rotation therewith; whereby rotation of the shaft and the pump assembly about the helical insert draws oil from the oil sump upwardly through the bore, and draws oil from the oil sump into the pump chamber and forces oil outwardly of the pump chamber through the opening in the plate.
In a further form thereof, the present invention provides a method of cooling an internal combustion engine, including the steps of rotating a shaft within the engine crankcase which includes a plate and an impeller mounted thereon, the impeller disposed within a pump housing at least partially defined by the plate; drawing oil from an oil sump within the engine crankcase into the pump housing through an inlet opening submerged within the oil sump; pressurizing the oil within the pump housing; directing the oil outwardly of the pump housing through at least one opening in the plate, in the form of a pressurized oil stream which rotates with the plate to contact a plurality of locations within the crankcase; transferring heat from the crankcase to the oil upon contact of the stream with the plurality of locations within the crankcase; and allowing the oil to drain from the plurality of locations within the crankcase into the oil sump.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
FIG. 1
is a perspective view of a small internal combustion engine, the crankcase of which is partially cut away to show the interior of the crankcase, including the crankshaft and the camshaft;
FIG. 2
is a perspective fragmentary view of a lower portion of the crankcase, and an exploded view of the various components of the lubrication assembly according to the present invention, looking downwardly along the components of the lubrication assembly;
FIG. 3
is a perspective fragmentary view of a lower portion of the crankcase, and an exploded view of the various components of the lubrication assembly according to the present invention, looking upwardly along the components of the lubrication assembly;
FIG. 4
is a sectional view of the lubrication assembly of the present invention, taken along line
4
—
4
of
FIG. 1
;
FIG. 5
is a bottom view of the crankcase and cylinder of the engine of
FIG. 1
, looking upwardly along line
5
—
5
of
FIG. 1
, showing the upper crankshaft and camshaft bearings;
FIG. 6
is a sectional view through a portion of the upper part of the crankcase, including the upper camshaft and upper crankshaft bearings, taken along line
6
—
6
of
FIG. 5
;
FIG. 7
is a cutaway perspective view of a portion of the crankcase of the engine of
FIG. 1
, showing a stream of pressurized oil directed from the impeller pump of the lubrication assembly to a plurality of locations within the crankcase as the cam gear rotates;
FIG. 8
is a chart showing the flow rate generated by the helical oil pump of the present lubrication assembly at varying pitches of the helical insert at an oil temperature of 45° C.; and
FIG. 9
is a chart showing the flow rate generated by helical oil pump of the present lubrication assembly at varying pitches of the helical insert at an oil temperature of 80° C.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrates preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention any manner.
DETAILED DESCRIPTION
Referring to
FIG. 1
, internal combustion engine
20
is shown, which includes a lubrication system according to the present invention, the details and operation of which are described below. Generally, engine
20
includes an engine housing with crankcase
22
, mounting flange
24
, cylinder block
26
, and cylinder head
28
. As shown in
FIGS. 1 and 5
, crankcase
22
is integrally formed with cylinder block
26
, with mounting flange
24
attached to crankcase
22
and cylinder head
28
attached to cylinder block
26
in a suitable manner; however, other arrangements for configuring the housing of engine
20
may be used.
Mounting flange
24
is typically attached to the deck of a lawnmower, the chassis of a lawn and garden tractor, or to another implement. Mounting flange
24
contains oil sump
30
therein, including an amount of oil for lubricating the various moving parts within engine
20
. Crankshaft
32
is shown vertically disposed within crankcase
22
, and is journalled in upper and lower crankshaft bearings
34
and
36
carried by crankcase
22
and mounting flange
24
, respectively. Crankshaft
32
includes power take-off (“PTO”) end
32
a
extending externally of mounting flange
24
, and an opposite end
32
b
extending externally of crankcase
22
for attachment thereto of a flywheel/blower (not shown) and/or a recoil starter assembly (not shown), for example. Crankshaft
32
additionally includes an eccentric crank pin
33
disposed between throws
35
. A piston (not shown) is operatively coupled to crank pin
33
via a connecting rod (not shown) in a conventional manner.
Additionally, camshaft
38
is supported for rotation within crankcase
22
by upper and lower camshaft bearings
40
(
FIGS. 5 and 6
) and
42
, carried by crankcase
22
and mounting flange
24
, respectively. Drive gear
44
is secured to crankshaft
22
, and engages camshaft gear
46
mounted to camshaft
38
such that camshaft
38
is driven by crankshaft
22
in timed relation. For example, in a four stroke engine, drive gear
44
and camshaft gear
46
are sized such that drive gear
44
drives camshaft gear
46
at one half crankshaft speed. Intake and exhaust valves
48
and
50
are disposed within cylinder block
26
and/or cylinder head
28
of engine
20
and are actuated via a suitable drive train coupling camshaft
38
to valves
48
and
50
. For example, in an overhead valve (“OHV”) engine, lobes
52
on camshaft
38
may actuate push rods (not shown) which in turn actuate rocker arms (not shown) within cylinder head
28
to open and close intake and exhaust valves
48
and
50
. Alternatively, in an overhead cam (“OHC”) engine, “camshaft”
38
may be drivingly connected to a separate camshaft (not shown) disposed within cylinder head
28
via a belt or chain drive, which camshaft engages intake and exhaust valves
48
and
50
to open and close same. One such OHC engine is disclosed in U.S. Pat. No. 6,295,959, assigned to the assignee of the present invention, the disclosure of which is expressly incorporated herein by reference. In a side valve or L-head engine, lobes
52
of camshaft
38
may directly actuate intake and exhaust valves within cylinder block
26
, or may indirectly actuate such valves through lifters (not shown). As will be apparent from the discussion below, the lubrication system of the present invention may be used in any number of internal combustion engines which may include various drive train configurations.
Referring to
FIGS. 2-4
, the present lubrication system will now be explained, which generally includes lubrication assembly
54
defining helical oil pump
56
and impeller oil pump
58
. As shown in
FIGS. 2 and 3
, mounting flange
24
includes lower crankshaft bearing
36
and lower camshaft bearing
42
. Oil sump
30
is carried within mounting flange
24
, and includes an amount of oil therein, wherein lower crankshaft bearing
36
and lower camshaft bearing
42
are normally submerged within the oil in oil sump
30
and are lubricated thereby.
Camshaft
38
includes hollow shaft portion
60
defining bore
62
therethrough which communicates upper end
38
a
and lower end
38
b
of camshaft
38
. Upper end
38
a
of camshaft
38
is supported for rotation in upper camshaft bearing
40
, as shown in
FIG. 6
, and lower end
38
b
of camshaft
38
is supported for rotation in lower camshaft bearing
42
, as shown in FIG.
4
. Shaft portion
60
of camshaft
38
includes exhaust lobes
52
and camshaft gear
46
mounted thereon. Shaft portion
60
of camshaft
38
may be made from a suitable metal, such as cast iron or steel, for example, and cam lobes
52
and camshaft gear
46
may be made from metal, or from a suitable plastic or resin material molded onto shaft portion
60
of camshaft
38
. If made of plastic, cam lobes
52
and camshaft gear
46
may be separately molded to shaft portion
60
, or alternatively, one or more of the foregoing may be formed together as a single component which is molded onto shaft portion
60
.
Helical insert
64
generally includes central shaft portion
66
having helical thread
68
disposed therearound. Helical insert
64
may be made from a single piece of metal, or from a wear resistant plastic or molded resin material, for example, and is received within bore
62
of camshaft
38
in a close sliding fit to define a helical space
70
(
FIGS. 4 and 6
) between bore
62
and helical thread
68
. Some exemplary materials from which Helical thread
68
may be made include polyamides, such as PA 66 unfilled Zytel 101 or 103; PA 66 glass filled Zytel 70 G20 (20 wt. % glass); PA 66 mineral filled Minion 10 B40 (40 wt. % mineral filled); PA 6 unfilled Zytel 7335; and PA 6 glass filled Zytel HTN 51 G35 (35 wt. % glass filled). Zytel and Minlon are registered trademarks of E.I. DuPont de Nemours Co., of Wilmington, Del.
Upper end
64
a
of helical insert
64
includes anchor portion
72
and, referring to
FIG. 6
, upper end
64
a
extends outwardly of upper end
38
a
of camshaft
38
with anchor portion
72
of helical insert
64
received within anchor recess
74
of upper camshaft bearing
40
. As shown herein, anchor portion
72
of helical insert
64
and anchor recess
74
of upper camshaft bearing
40
include complementary square-shaped or other non-circular profiles, such that helical insert
64
may not rotate, but rather is rotatably fixed with respect to crankcase
22
. The foregoing materials of helical insert
64
are resistant to wear upon frictional contact with shaft portion
60
of camshaft
38
as camshaft
38
rotates around helical insert
64
, as described below.
Referring to
FIG. 4
, lower end
64
b
of helical insert
64
extends outwardly beyond lower end
38
b
of camshaft
38
, wherein lower end
64
b
of helical insert
64
and lower end
38
b
of camshaft
38
are submerged within oil contained within chamber
78
of lower camshaft bearing
42
. Oil may enter chamber
78
from oil sump
30
through passages
80
.
Referring to
FIG. 6
, crankcase
22
includes passage
82
therethrough connecting space
84
of upper camshaft bearing
40
with upper crankshaft bearing
34
. Specifically, passage
82
fluidly communicates with annular groove
86
formed in crankshaft bearing
34
around crankshaft
32
, and annular groove
86
in turn fluidly communicates with axial groove
88
formed longitudinally along upper crankshaft bearing
34
parallel to crankshaft
32
. Passage
82
may be formed by drilling a bore through exterior wall
22
a
of crankcase
22
through space
84
of upper camshaft bearing
40
to annular groove
86
of upper crankshaft bearing
34
, followed by inserting plug
90
into wall
22
a
of crankcase
22
via a press fit or a screw-threaded engagement, for example, to close passage
82
.
In operation, rotation of camshaft
38
around helical insert
64
causes oil to be drawn from chamber
78
of lower camshaft bearing
42
into camshaft bore
62
, where the oil is then drawn upwardly within camshaft
38
through the helical space defined between bore
62
and helical thread
68
. In this manner, the oil is forced to “climb” helical insert
64
. Referring to
FIG. 6
, oil is drawn upwardly to upper end
38
b
of camshaft
38
and is forced under pressure into space
84
within upper camshaft bearing
40
. Thereafter, a first portion of the oil within space
84
lubricates the sliding interface between upper end
38
a
of camshaft
38
and upper camshaft bearing
40
, before exiting upper camshaft bearing
40
and dripping downwardly back into oil sump
30
.
Another, second portion of the oil within space
84
is directed through passage
82
into annular groove
86
of upper crankshaft bearing
34
before passing through axial groove
88
and exiting upper crankshaft bearing
34
and dripping downwardly back into oil sump
30
. The conveyance of oil around annular groove
86
and axial groove
88
in upper crankshaft bearing
34
, as crankshaft
32
rotates within upper crankshaft bearing
34
, distributes oil evenly over the sliding interface between crankshaft
32
and upper crankshaft bearing
34
. In this manner, helical oil pump
56
provides pressurized oil lubrication directly to upper camshaft bearing
40
and to upper crankshaft bearing
34
.
In
FIGS. 8 and 9
, various flow rates of oil through helical oil pump
56
are shown with varying pitch of helical thread
68
of helical insert
64
at oil temperatures of 45° C. and 80° C. Generally, the oil has a greater viscosity at 45° C. than at 80° C. Referring first to
FIG. 8
, at an oil temperature of 45° C., which corresponds to a relatively cool engine temperature immediately after engine starting, for example, the flow rate Q (cc/min.) of oil through helical oil pump
56
is greatest when the pitch of helical insert
64
is 8 millimeters (mm) throughout engine speeds ranging from 2000 rpm to 3600 rpm. The pitch of helical insert
64
is expressed herein in millimeters (mm) as the distance between adjacent threads. Further, at 45° C., the flow rate for pitch 12 mm is greater than that for pitch 4 mm throughout the speed range of 2000 rpm to 3600 rpm.
Referring to
FIG. 9
, at an oil temperature of 80° C. which corresponds to an engine running temperature, the flow rate Q (cc/min.) of oil through helical oil pump
56
remains greatest when the pitch of helical insert
64
is 8 mm throughout engine speeds ranging from 2000 rpm to 3600 rpm. At 80° C., the flow rate for pitch 4 mm is greater than that for pitch 12 mm until the engine speed reaches approximately 3300 rpm, wherein at higher engine speeds, the flow rate for pitch 12 mm is greater than that for pitch 4 mm. From
FIGS. 8 and 9
, it may be seen that helical oil pump
56
is somewhat more effective in pumping oil when the oil has a relatively greater viscosity at a low oil temperature than when the oil has a relatively lesser viscosity at higher oil temperatures.
Referring to
FIGS. 2-4
, details of impeller oil pump
58
will now be explained. Referring first to
FIG. 3
, camshaft
38
includes collar
94
having a plurality of impeller blades
96
projecting therefrom. Collar
94
may be made from a suitable plastic or resin material molded onto camshaft
38
. Further, collar
94
may comprise a separate component mounted to camshaft
38
, or alternatively, may be integrally formed with camshaft gear
46
. Although impeller oil pump
58
is described below as an impeller-type pump, oil pump
58
may also be configured, with minor modifications to the components of oil pump
58
, as a gerotor-type pump, a plunger pump, or another suitable pump.
As shown in
FIGS. 2 and 3
, pump body
100
is a generally cup-shaped component made from metal or a suitable rigid plastic material, for example. Pump body
100
generally includes base wall
102
, and annular side wall
104
extending from base wall
102
and terminating in outer rim
106
. Base wall
102
includes a plurality of oil inlet slots
108
disposed around camshaft opening
110
through which camshaft
38
extends. As shown in
FIG. 4
, at least a portion of pump body
100
is normally submerged within the oil in oil sump
30
, such that oil may enter pump body
100
through oil inlet slots
108
. Locating flange
112
of pump body
100
projects from base wall
102
and/or side wall
104
, and fits within grooves
112
of lower camshaft bearing
42
, as shown in
FIG. 2
, to locate pump body
100
with respect to lower camshaft bearing
42
, and also to fix pump body
100
against rotation with respect to mounting flange
24
.
Referring to
FIG. 4
, camshaft
38
is inserted through camshaft opening
110
(
FIG. 3
) in base wall
102
of pump body
100
such that collar
94
and impeller blades
96
are received within pump body
100
. Washer
115
is disposed between collar
94
and pump body
100
. Camshaft gear
46
abuts outer rim
106
of pump body
100
in a sliding bearing contact, such that camshaft gear
46
closes pump body
100
to define pump chamber
114
between pump body
100
and camshaft gear
46
, and wherein camshaft gear
46
is rotatable with camshaft
38
while pump body
100
is rotatably fixed with respect to mounting flange
24
and does not rotate.
In operation, camshaft gear
46
is rotatably driven by crankshaft
32
of engine
20
through drive gear
44
, and rotates camshaft
38
. Rotation of camshaft
38
rotates impeller blades
96
within pump body
100
, thereby drawing oil from oil sump
30
through inlet slots
108
of pump body
100
into pump chamber
114
. Oil is forced outwardly of pump chamber
114
through hole
116
in camshaft gear
46
. Due to the relatively small size of hole
116
in camshaft gear
46
in proportion to the relatively larger size of inlet slots
108
in pump body
100
, oil is pressurized within pump chamber
114
. Thus, oil is forced outwardly of pump chamber
114
through hole
116
in camshaft gear
46
in the form of a pressurized oil stream
118
which, as shown in
FIG. 7
, rotates with opening
116
in camshaft gear
46
as camshaft gear
46
rotates. In this manner, pressurized oil stream
118
is directed to a plurality of locations within crankcase
22
as camshaft gear
46
rotates, such as crank pin
33
, throws
35
, and the inner walls
22
b
of crankcase
22
.
Oil contacting the inner walls
22
b
of crankcase
22
absorbs heat from crankcase
22
which is generated during running of engine
20
, and the oil then drips downwardly back into oil sump
30
to disperse the heat within oil sump
30
. Advantageously, impeller oil pump
58
circulates a relatively large amount of oil continuously within crankcase
22
and, due to the spray contact of oil within pressurized oil stream
118
with inner walls
22
b
of crankcase
22
, crankcase
22
is cooled to reduce the overall operating temperature of engine
20
. For example, it has been found that the oil distribution and circulation action of impeller oil pump
58
decreases the temperature of the oil within engine
20
about 20° C. from the normal temperature of the oil within engine
20
when engine
20
is at running speeds.
Although a single opening
116
has been shown within camshaft gear
46
in the form of a hole in
FIGS. 2 and 7
, camshaft gear
46
may include multiple openings therein for directing oil streams to various selected points of contact within crankcase
22
to lubricate certain components within crankcase
22
and/or to cool crankcase
22
. Additionally, the size, shape, and directional orientation of such openings may be varied as desired to direct one or more pressurized oil streams in desired directions within crankcase
22
. Further, camshaft gear
46
may include a tube or other suitable structure having an opening or passageway therein, which is molded or inserted within camshaft gear
46
and through which pressurized oil stream
118
is directed.
The engagement between drive gear
44
and camshaft gear
46
may be timed with respect to the location of openings
116
in camshaft gear
46
, such that the direction and spray of pressurized oil stream
118
is selectively determined based upon the location of other moving components with crankcase relative to opening
116
in camshaft gear
46
. For example, drive gear
44
and camshaft gear
46
may be timed such that opening
116
is disposed directly beneath crank pin
33
once every rotation of camshaft gear
46
, so that pressurized oil stream
118
directly contacts crank pin
33
to lubricate the connection point between crank pin
33
and the connecting rod (not shown) during every rotation of camshaft gear
46
. Also, drive gear
44
and camshaft gear
46
may be timed such that opening
116
is disposed directly beneath throws
35
of camshaft
32
once every rotation of camshaft gear
46
, such that pressurized oil steam
118
is directed directly against throws
35
and is thereby deflected in multiple directions within crankcase
22
.
In this manner, helical oil pump
56
and impeller oil pump
58
cooperate to lubricate the moving parts of engine
20
. Specifically, helical oil pump
56
provides a supply of pressurized lubricating oil directly to upper camshaft bearing
40
and upper crankshaft bearing
34
to lubricate same, and impeller oil pump
58
directs one or more streams
118
of pressurized oil to selected locations within crankcase
22
to lubricate the moving parts within crankcase
22
with pressurized oil. Additionally, the streams
118
of pressurized oil from oil pump
58
contact the interior walls
22
a
of crankcase
22
and absorb heat therefrom before dripping back into oil sump
30
and, due to the relatively large amount of oil which is continuously circulated within crankcase
22
by impeller oil pump
58
, an engine cooling effect is provided.
While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Claims
- 1. An internal combustion engine, comprising:a crankcase containing an oil sump therein; a crankshaft rotatably supported within said crankcase; a second shaft rotatably supported within said crankcase in timed driven relationship with said crankshaft, said second shaft disposed vertically and including a bore therethrough which communicates between upper and lower ends of said second shaft; and a helical insert disposed within said bore, said helical insert rotationally fixed with respect to said crankcase, said lower end of said second shaft and said helical insert in communication with said oil sump wherein rotation of said second shaft about said helical insert draws oil from said oil sump upwardly through said bore.
- 2. The internal combustion engine of claim 1, wherein said helical insert includes an upper end portion extending outwardly of said upper end of said second shaft, said upper end portion of said helical insert rotationally fixed with respect to said crankcase.
- 3. The internal combustion engine of claim 1, wherein said helical insert includes a lower end portion disposed proximate said lower end of said second shaft, said lower end portion of said helical insert and said lower end of said second shaft submerged within oil of said oil sump.
- 4. The internal combustion engine of claim 1, wherein said helical insert comprises a central shaft having a helical thread therearound.
- 5. The internal combustion engine of claim 1, wherein said upper end of said second shaft is rotatably supported in an upper second shaft bearing, and said oil drawn upwardly through said bore of said second shaft is carried to said upper second shaft bearing to lubricate same.
- 6. The internal combustion engine of claim 5, wherein said crankshaft is disposed vertically, and includes an upper end rotatably supported in an upper crankshaft bearing, said crankcase including a passage communicating said upper second shaft bearing with said upper crankshaft bearing, wherein oil from said upper second shaft bearing is carried through said passage to said upper crankshaft bearing to lubricate same.
- 7. The internal combustion engine of claim 6, wherein said upper crankshaft bearing includes an annular groove therearound in communication with said passage, and an axial groove in communication with said annular groove, said annular and axial grooves distributing oil around said crankshaft upper end as said crankshaft rotates.
- 8. The internal combustion engine of claim 1, wherein said second shaft is a camshaft including at least one cam lobe thereon.
- 9. The internal combustion engine of claim 8, wherein said crankshaft drives said camshaft through a gear set, comprising;a drive gear mounted on said crankshaft; and a cam gear mounted on said camshaft; said drive gear engaging said cam gear.
- 10. An internal combustion engine, comprising:a crankcase containing an oil sump therein; a shaft rotatably supported within said crankcase; a plate mounted on said shaft and rotatable therewith, said plate having at least one opening therethrough; a pump body fixed with respect to said crankcase and in fluid communication with said oil sump, said pump body and said plate defining a pump chamber therebetween; and a pump assembly disposed within said pump chamber and mounted on said shaft for rotation therewith; whereby rotation of said shaft and said pump assembly draws oil from said oil sump into said pump chamber and forces oil outwardly of said pump chamber through said opening in said plate.
- 11. The internal combustion engine of claim 10, wherein said pump assembly forces oil through said opening in said plate in the form of a pressurized oil stream which is directed toward different locations within said crankcase as said plate rotates.
- 12. The internal combustion engine of claim 10, wherein said plate comprises a gear mounted on said shaft and rotatable therewith, said gear having at least one opening therethrough.
- 13. The internal combustion engine of claim 12, wherein said shaft is a camshaft, said camshaft driven in timed relation by a crankshaft rotatably supported within said crankcase through a drive gear on said crankshaft which drives said gear.
- 14. The internal combustion engine of claim 10, wherein said pump body comprises a cup-shaped component having a rim portion in bearing contact with said plate.
- 15. The internal combustion engine of claim 10, wherein said pump body includes at least one inlet opening submerged within said oil sump.
- 16. The internal combustion engine of claim 10, wherein said plate and said pump assembly are integrally formed.
- 17. The internal combustion engine of claim 10, wherein said shaft includes an end extending through said pump body, said shaft end supported in a bearing carried by said crankcase.
- 18. The internal combustion engine of claim 10, wherein said pump assembly comprises a plurality of impeller blades.
- 19. An internal combustion engine, comprising:a crankcase containing an oil sump therein; a shaft rotatably supported within said crankcase, said shaft including a bore therethrough which communicates between upper and lower ends of said shaft; a helical insert disposed within said bore, said helical insert rotationally fixed with respect to said crankcase, said lower end of said second shaft and said helical insert in communication with said oil sump; a plate mounted on said shaft and rotatable therewith, said plate having at least one opening therethrough; a pump body fixed with respect to said crankcase and in fluid communication with said oil sump, said pump body and said plate defining a pump chamber therebetween; and an pump assembly disposed within said pump chamber and mounted on said shaft for rotation therewith; whereby rotation of said shaft and said impeller assembly about said helical insert draws oil from said oil sump upwardly through said bore, and draws oil from said oil sump into said pump chamber and forces oil outwardly of said pump chamber through said opening in said plate.
- 20. A method of cooling an internal combustion engine, comprising the steps of:rotating a shaft within the engine crankcase which includes a plate and an impeller mounted thereon, the impeller disposed within a pump housing at least partially defined by the plate; drawing oil from an oil sump within the engine crankcase into the pump housing through an inlet opening submerged within the oil sump; pressurizing the oil within the pump housing; directing the oil outwardly of the pump housing through at least one opening in the plate, in the form of a pressurized oil stream which rotates with the plate to contact a plurality of locations within the crankcase; transferring heat from the crankcase to the oil upon contact of the stream with the plurality of locations within the crankcase; and allowing the oil to drain from the plurality of locations within the crankcase into the oil sump.
US Referenced Citations (34)