Information
-
Patent Grant
-
6792900
-
Patent Number
6,792,900
-
Date Filed
Thursday, September 26, 200222 years ago
-
Date Issued
Tuesday, September 21, 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 73 AD
- 123 196 R
- 184 1
- 184 5
- 184 14
-
International Classifications
-
Abstract
A lubrication system for two-cycle engine includes a lubricant recess formed in a wall of a crankcase. Oil that becomes deposited within the intake passageway is directed to the lubricant recess preferably by a guide groove and pools adjacently below a connecting rod endcap. As the crankshaft with attached connecting rod rotates, pooled oil is drawn into the interior of the connecting rod endcap. Preferably, oil holes are formed radially outward through the connecting rod endcap to throw collected oil around the crankcase chamber when exposed to a centrifugal force.
Description
PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Application No. 2001-301620, filed Sep. 28, 2001 the entire contents of which is hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to oil injection lubrication for engines and more particularly to oil injection systems and methods for lubricating a two-cycle engine.
2. Description of the Related Art
In two-cycle engines, it is a common practice to mix lubricating oil with induction air to lubricate engine parts. Typically, the intake air is pre-compressed inside a crank chamber before being sent into the cylinders. In this type of two-cycle engine, oil is guided to an intake passage and further into the engine by the intake air. More specifically, the oil encounters the intake air inside the intake passage and is misted therein. The misted oil is then drawn into the crank chamber as the piston ascends and a valve opens to allow intake air to enter the crank chamber. The misted oil lubricates rotating parts in and around the crankshaft and within the interior wall of the cylinder.
In conventional two-cycle engines, fuel mixes with the intake air inside the intake passageway to reduce the viscosity of the oil which promotes misting of the oil. However, in direct injection-type two-cycle engines in which the fuel is directly sprayed into the combustion chamber, the viscosity of the oil drawn into the crank chamber is not reduced by dilution with the fuel. The undiluted liquid oil is, therefore, more difficult to convert into a mist. Since the oil may not be sufficiently misted in the intake air, the amount of oil supplied to the engine may be reduced. Insufficiently misted oil results in liquid oil depositing onto the interior wall surface inside the intake passageway. More liquid oil deposits on the wall surfaces of the intake passageway when the flow of intake air decreases, such as during low speed operation.
SUMMARY OF THE INVENTION
One aspect of the present invention includes the realization that the rotation of the crankshaft of an internal combustion engine can be used to redistribute oil that has condensed in the crankcase chamber. For example, a lubricant recess can be preferably located adjacent, and generally below, a throw of a vertically-oriented crankshaft, such that a connecting rod endcap attached to the crankshaft throw passes over the recess during at least a portion of its rotational travel. The endcap is preferably configured with radial oil holes to help establish a flow path caused by a pressure differential due to rotation of the crankshaft. In at least one embodiment, the pressure differential is sufficient to draw oil from the recess into the endcap and throw the oil about the crankcase chamber.
According to another aspect of the present invention, a lubrication system for a two-cycle engine is provided. The engine, which may be of the direct fuel injection type, has a vertical crankshaft and a lubrication recess disposed generally adjacent to a throw of the crankshaft. The lubrication recess opens upwardly such that at least a portion of a connecting rod endcap passes over the recess.
The lubrication recess is preferably formed in an interior wall of the engine crankcase. Liquid oil may be directed to the lubrication recess by a guide groove that extends from an air intake of the crankcase to the lubrication recess.
The endcap preferably has one or more holes formed therethrough and providing an opening in an interior surface of the endcap and an opening in the exterior surface of the endcap. As the crankshaft rotates, the opening in the interior surface of the endcap preferably passes over the lubrication recess during a predetermined range of crankshaft rotation.
According to another aspect, a two-stroke engine has one or more cylinders with each cylinder having a piston, a vertical crankshaft, and a connecting rod that connects the piston to a throw of the crankshaft. The connecting rod has an endcap that allows it to connect to the crankshaft throw, the endcap having one or more oil holes formed therethrough thus providing fluid communication between an opening in an interior peripheral surface and an opening in an exterior peripheral surface of the endcap. A lubrication recess is formed adjacent the crankshaft and generally below a crankshaft throw. As the crankshaft rotates, each opening in the interior peripheral surface of the endcap to pass over the lubrication recess.
The crankshaft rotation can cause a pressure differential between the interior and exterior surfaces of the endcap sufficient to draw oil from within the lubrication recess upwardly and into the interior peripheral surface opening. The oil is then thrown through the exterior peripheral surface opening.
Another aspect of the present invention is directed to an outboard motor having a powerhead, a driveshaft housing depending from the powerhead, and a lower unit connect to and disposed below the driveshaft housing. The powerhead includes an internal combustion engine coupled to a propeller of the lower unit through a driveshaft extending through the driveshaft housing for propelling a watercraft. The internal combustion engine further has a cylinder block defining a cylinder bore and a cylinder head connected to the cylinder block. The cylinder head has a recess in one of its surfaces which cooperates with a piston surface and the cylinder bore to define a combustion chamber.
A vertical crankshaft is configured for rotation within a crankcase chamber formed, in part, by a crankcase member, and is coupled to the piston through a connecting rod that has a large end engaging the crankshaft and a small end engaging the piston. The crankcase member further defines an air intake passageway having an air and oil regulating valve disposed therein.
A lubrication recess is formed by the crankcase member and is disposed generally below the large end of the connecting rod during at least a range of the crankshaft rotation. The crankcase member further defines a guide groove configured to urge deposited lubricant to flow toward the lubricant recess.
The large end of the connecting rod draws lubricant from the lubricant recess and throws the lubricant within the crankcase chamber.
According to yet another aspect, a two-stroke internal combustion engine includes one or more cylinders and a piston for reciprocating within each cylinder. A connecting rod is rotatably coupled to each piston and is further coupled to a throw of a vertical crankshaft by an endcap. The crankshaft and connecting rod are disposed within a crankcase chamber.
One or more oil holes are formed radially through the endcap thereby providing fluid communication between a first opening disposed inwardly from an outer peripheral surface and a second opening in the outer peripheral surface of the endcap.
A lubrication recess can be disposed adjacent the crankshaft and generally below a throw of the crankshaft during at least a range of its rotation. Rotation of the crankshaft may cause lubricant from within the lubrication recess to be drawn into the first opening and discharged out of the second opening. Rotation of the crankshaft can cause a pressure differential sufficient to draw lubricant into the first opening. The lubricant can further be used to lubricate the coupling between the connecting rod and the throw of the crankshaft.
The crankshaft rotation can additionally or alternatively cause the endcap to splash the lubricant within the lubrication recess thereby forcing lubricant into the first opening.
A guide groove may be provided in a lower surface of the crankcase and extend generally from an air intake of the crankcase to the lubrication recess.
According to another aspect, a two-stroke internal combustion engine has one or more cylinder each having a piston for reciprocation therein. Each piston is rotatably coupled to a connecting rod which is, in turn, coupled to a throw of a crankshaft by an endcap. The crankshaft is disposed generally vertically within a crankcase chamber of the engine. A lubrication recess is disposed adjacent to the crankshaft and generally below a throw of the crankshaft.
Liquid oil within the crankcase chamber may collect within the lubrication recess, after which the endcap and/or connecting rod can throw the collected oil about the crankcase chamber.
According to yet another aspect, an outboard motor has an internal combustion engine with a crankshaft journaled for rotation within a crankcase and couple to a driveshaft for rotating a propeller connect to the driveshaft. The internal combustion engine includes means for causing oil to pool adjacent a throw of the crankshaft and means for redistributing pooled oil around the crankcase.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic diagram illustrating the fuel and oil supply system of an engine in which one embodiment of the lubrication system of the present invention is invented.
FIG. 2
is a partial top plan and a cross-sectional view of the outboard motor illustrated in
FIG. 1
, showing a crankshaft and piston rod assembly with in a case of the engine.
FIG. 3
is an enlarged cross-sectional view of the crankshaft and piston rod assembly of FIG.
2
.
FIG. 4
is a partial sectional and side elevational view of the engine showing the crankshaft, piston rod assembly, and reed valves mounted to the crankcase of the engine.
FIG. 5
is an enlarged cross-sectional view of
FIG. 4
schematically showing a flow of air and oil through the reed valve and connecting rod assembly.
FIG. 6
is a front elevational view of the crankcase and crankshaft.
FIG. 7
is a front elevational view of a portion of the crankshaft removed from the engine.
FIG. 8A
is a top plan view of a connecting rod removed from the engine.
FIG. 8B
is a cross-sectional view taking along line B—B of FIG.
8
A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following description, reference is made to the accompanying drawings which form a part of this written description which show, by way of illustration, specific embodiments in which the invention can be practiced. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Where possible, the same reference numbers will be used throughout the drawings to refer to the same or like components. Numerous specific details are set forth in order to provide a thorough understanding of the present invention; however, it would be obvious to one skilled in the art that the present invention may be practiced without the specific details or with certain alternative equivalent devices and methods to those described herein. In other instances, well-known methods, procedures, components and devices have not been described in detail so as not to unnecessarily obscure aspects of the present invention.
With reference to
FIG. 1
, and initially Section A, an outboard motor constructed and operated in accordance with a preferred embodiment of the invention is depicted in a side elevational view and is identified generally by the reference numeral
100
. The entire outboard motor
100
is not depicted in that the swivel bracket and the clamping bracket which are associated with the driveshaft housing indicated generally by the reference numeral
102
are not illustrated. These components are well known in the are and thus the specific method by which the outboard motor
100
is mounted to the transom of an associated watercraft is not necessary to permit those skilled in the art to understand or practice the invention.
The outboard motor
100
includes a powerhead indicated generally by the reference numeral
104
. The powerhead
104
is positioned above the driveshaft housing
102
and includes a powering internal combustion engine indicated generally by the reference numeral
106
. The engine
106
is shown is more detail in the remaining three views of FIG.
1
and is described below with reference thereto.
The powerhead
104
is completed by a protective cowling formed by a main cowling member
108
and a lower tray
110
. The main cowling member
108
is detachably connected to the lower tray
110
. The lower tray
110
encircles an upper portion of the driveshaft housing
102
and a lower end of the engine
106
.
Positioned beneath the driveshaft housing
102
and coupled thereto is a lower unit
112
in which a propeller
114
which forms the propulsion device for the associated watercraft is journaled. As is typical with outboard motor practice, the engine
106
is supported in the powerhead
104
so that its crankshaft
116
(see Section B of
FIG. 1
) rotates about a vertically extending axis. This facilitates connection of the crankshaft
116
to a driveshaft which extends into the lower unit
112
and which drives the propeller
114
through a conventional forward-neutral-reverse transmission contained in the lower unit
112
.
The details of the construction of the outboard motor
100
and the components which are not illustrated may be considered to be conventional or of any type known to those wishing to utilize the invention disclosed herein. Those skilled in the art can readily refer to any known constructions of such with which to practice the invention.
With reference now in detail to the construction of the engine
106
still by primary reference to
FIG. 1
, the illustrated embodiment of the engine
106
is of the V6-type and operates on a two-stroke crankcase compression principal. Although the invention is described in conjunction with an engine having a particular cylinder number and cylinder configuration, it will be readily apparent that the invention can be utilized with engines having other cylinder numbers and other cylinder configurations. Also, although the engine
106
is described as operating on a two-stroke principal, it will also be apparent to those skilled in the art that certain facets of the invention can be employed in conjunction with four-stroke engines. Some features of the invention may also be employed with rotary-type engines.
With reference primarily to Sections B and D of
FIG. 1
, the engine
106
comprises a cylinder block
118
that is formed with a pair of cylinder banks
120
. Each of the cylinder banks
120
comprises three vertically spaced, horizontally extending cylinder bores
122
. The cylinder bores
122
are numbered #
1
-
6
from top to bottom and will be referred to individually as cylinder
1
, cylinder
2
, etc. Pistons
124
reciprocate in the cylinder bores
122
. The pistons
124
are in turn connected to the upper or small ends of connecting rods
126
. The big ends of these connecting rods are journaled on the throws of the crankshaft
116
in a manner that is well-known in the art.
The crankshaft
116
is journaled in a suitable manner for rotation within a crankcase chamber
128
that is formed by part of the cylinder block
118
and by the crankcase member
130
. The crankcase member
130
is affixed to the cylinder block
118
in a suitable manner. As is typical with two-cycle engines, the crankshaft
116
, cylinder block
130
, and crankcase member
130
are formed with seals so that each section of the crankcase
128
which is associated with one of the cylinder bores
122
, is sealed from the other sections. This type of construction is well-known in the art.
With additional reference to
FIG. 2
, a cylinder head assembly, indicated generally by the reference numeral
202
, is affixed to an end of each cylinder bank
120
that is spaced from the crankcase chamber
128
. The cylinder head assemblies
202
comprise a main cylinder head member
204
that defines a plurality of recesses
206
on its inner face. Each of these recesses
206
cooperate with a respective cylinder bore
122
and the head of the piston
124
to define the combustion chambers of the engine as is well known in the art. A cylinder head cover member
208
completes the cylinder head assembly
202
. The cylinder head members
204
,
208
are affixed to each other and to the respective cylinder banks
120
in a suitable known manner.
With reference again primarily to
FIG. 1
, Sections B and C, an air induction system indicated generally by the reference numeral
132
is provided for delivery of an air charge to the sections of the crankcase chamber
128
associated with each of the cylinder bores
122
. This communication is via an intake port
134
formed in the crankcase member
130
and registering with each such crankcase chamber section.
The induction system
132
includes an air silencing and inlet device shown schematically in this FIG.
1
and indicated by the reference numeral
136
. The device
136
is typically contained within the cowling
108
at the forward end thereof and has a rearwardly facing air inlet opening
138
through which air is drawn. Air is admitted into the interior of the cowling
108
in a known manner such as primarily through a pair of rearwardly positioned air inlets as is generally well-known in the art.
The air inlet device
136
supplies the induced air through a plurality of throttle bodies
140
, each of which includes a throttle valve
142
positioned therein. The throttles valves
142
are supported for rotation on throttle valve shafts (not shown). The throttle valve shafts are linked to each other for simultaneous opening and closing of the throttle valves
142
in a manner well-known in the art.
As is also typical in two-cycle engine practice, the intake ports
134
are provided with reed-type check valves
144
. The check valves
144
permit air to flow into the sections of the crankcase chamber
128
when the pistons
124
are moving toward the recesses
206
in their respective cylinder bores
122
. As the pistons
124
move toward the crankcase
128
, the charge is compressed in the sections of the crankcase chamber
128
. At that time, the reed-type check valve
144
closes so as to permit the charge to be compressed.
In accordance with at least one preferred embodiment of the present invention, an oil pump
146
pumps oil to a solenoid valve unit
150
through an oil delivery hose
151
. In one preferred embodiment, the oil pump
146
is driven by the crankshaft
116
; however, an electric oil pump may be used in the alternative. The solenoid valve unit
150
may regulate the delivery of oil to the throttle body
140
of each cylinder
122
, in which case, the oil passes through the throttle body
140
and into the crankcase chamber
128
to lubricate the components of each cylinder
122
. The air charge, which is compressed in the sections of the crankcase chamber
128
, is then transferred to the combustion chamber through a scavenging system (not shown) in a manner that is well known.
A sparkplug
152
is mounted in the cylinder head assembly
202
for each cylinder bore. The sparkplug
152
is fired under control of an ECU
148
(electronic control unit). The ECU
148
receives certain signals for controlling the timing of firing of the sparkplugs
152
in accordance with any desired control strategy.
The sparkplug
152
ignites a fuel-air charge that is formed by mixing the intake air with fuel supplied from a fuel delivery system
154
. With reference to Section C and D of
FIG. 1
, the fuel supply system
154
is configured to supply fuel to the combustion chambers through fuel injectors
156
. In the illustrated embodiment, the fuel system
154
comprises a main fuel supply tank
158
that is provided in the hull of the watercraft with which the outboard motor
100
is associated. Fuel is drawn from this tank
158
through a conduit
160
by a first low pressure pump
162
and a plurality of second low pressure pumps
164
. The first low pressure pump
162
is a manually operated pump and the second low pressure pumps
164
are diaphragm-type pumps operated by variations in pressure in the sections of the crankcase chamber
128
and thus provide a relatively low pressure. A quick disconnect coupling is provided in the conduit
160
and a fuel filter
166
is positioned in the conduit
160
in an appropriate location.
From the low pressure pump
164
fuel is supplied through a vapor separator
168
which is mounted on the engine
106
or within the cowling
108
at an appropriate location. This fuel is supplied through a line
169
and a float valve regulates fuel flow through the line
169
. The float valve is operated by a float that is disposed within the vapor separator
168
so as to maintain a generally constant level of fuel in the vapor separator
168
.
A high pressure electric fuel pump
170
is provided in the vapor separator
168
and pressurizes fuel that is delivered through a fuel supply line
171
to a high pressure fuel pump indicated generally by the reference numeral
172
. The electric fuel pump
170
which is driven by an electric motor develops a pressure such as within the range of from about 3 to about 10 kg/cm
2
. A low pressure regulator
170
A is positioned in the line
171
at the vapor separator
168
and limits the pressure that is delivered to the high pressure fuel pump
172
by dumping the fuel back to the vapor separator
168
.
With reference to Section D of
FIG. 1
, fuel is supplied from the high pressure fuel pump
172
to a pair of vertically extending fuel rails
173
through a flexible pipe
173
A. The pressure in the high pressure pump
172
is regulated by a high pressure regulator
174
which dumps fuel back to the vapor separator
168
through a pressure relief line
175
in which a fuel heat exchanger or cooler
176
may be provided.
After the fuel charge has been formed in the combustion chamber by the injection of fuel from the fuel injectors
156
, the charge is fired by firing sparkplugs
152
. The injection timing and duration, as well as the control for the timing of firing of the sparkplugs
152
are controlled by the ECU
148
.
As the charge burns and expands, the pistons
124
are driven toward the crankcase chamber
128
in the cylinder bores
122
until the pistons
124
reach the lower most position (i.e., bottom dead center). Through this movement, an exhaust port (not shown) is opened to communicate with an exhaust passage
177
formed in the cylinder block
118
. The exhaust gases flow through the exhaust passages
177
to collector sections of respective exhaust manifolds that are formed within the cylinder block
118
. These exhaust manifold collector sections communicate with exhaust passages formed in an exhaust guide plate on which the engine
106
is mounted.
The ECU
148
controls the timing and duration of fuel injection. The ECU
148
thus controls the opening and closing of the solenoid valves of the fuel injectors
156
and in particular controls the selective supply of current to the solenoids of the fuel injectors
156
.
A pair of exhaust pipes
178
extend the exhaust passages
177
into an expansion chamber
179
formed in the driveshaft housing
102
. From this expansion chamber
179
, the exhaust gases are discharged to the atmosphere through a suitable exhaust system. The length of the exhaust pipes
178
from the cylinder
122
to the head of the exhaust pipe
178
differs between some or all of the cylinders
122
. As is well-known in outboard motor practice, this may include an underwater, high-speed, exhaust gas discharge and an above-water low speed exhaust gas discharge. Since these types of systems are well-known in the art, further description is not necessary to permit those skilled in the art to practice the invention.
Any type of desired controlled strategy can be employed for controlling the time and duration of fuel injection from the injectors
154
and timing of firing of the sparkplug
152
. However, a general discussion of some engine conditions and other ambient conditions that can be sensed for engine control will follow. It is to be understood, however, that those skilled in the art will readily understand how various control strategies can be employed in conjunction with the components of the invention.
The control for the fuel air ratio preferably includes a feedback control system. Thus, a combustion condition or oxygen sensor
180
is provided and determines the in-cylinder combustion conditions by sensing the residual amount of oxygen in the combustion products at about a time when the exhaust port is opened. This output signal is carried by a line to the ECU
148
as schematically illustrated in FIG.
1
.
As shown in Section B of
FIG. 1
, a crank angle position sensor
181
measures the crank angle and transmits it to the ECU
148
as schematically indicated. Engine load as determined by throttle angle of the throttle valve
142
is sensed by a throttle position sensor
182
which outputs a throttle position or load signal to the ECU
148
.
There is also provided a pressure sensor
183
communicating with the fuel line connected to the pressure regulator
174
. This pressure sensor
183
outputs the high-pressure fuel signal to the ECU
148
. Further, an intake air temperature sensor
185
may be provided when this sensor
185
outputs an intake air temperature signal to the ECU
148
.
The sense conditions are merely some of those conditions which may be sensed for engine control and it is, of course, practicable to provide other sensors such as, for example, but without limitation, an engine height sensor, a knock sensor, a neutral sensor, a watercraft pitch sensor and an atmospheric temperature sensor in accordance with various control strategies.
The ECU
148
computes and processes the detection signals of each sensor based on a control strategy. The ECU
148
forwards control signals to the fuel injector
156
, sparkplug
152
, the electromagnetic solenoid valve unit
150
and the high-pressure electric fuel pump
170
for their respective control. These control signals are carried by respective control lines that are indicated schematically in FIG.
1
.
With reference to Section C of
FIG. 1
, an oil subtank
187
located in the hull of the watercraft serves as a reservoir of lubrication oil for the engine
106
. A suitable delivery pump supplies oil from the oil subtank
187
through the oil supply pipe
187
A to a main oil tank
188
mounted to the side of the cylinder block
118
. The delivery pump can, for example, be located within the oil subtank
187
or can be positioned within the supply pipe
187
A and can be either electrically or mechanically driven. An oil feedpipe
189
supplies oil from the bottom of the main oil tank
188
to the oil pump
146
. The oil pump
146
in turn supplies oil to the solenoid valve unit
150
which regulates the flow of oil to the cylinders. The solenoid valve unit
150
is preferably controlled via control signals from the ECU
148
.
In one preferred embodiment, oil is also delivered directly to the vapor separator chamber
168
. A premixing oil pump
193
draws oil from the oil feedpipe
189
and through a premixing oil filter
195
. The oil also passes through a reed-type check valve
197
and is then delivered to the vapor separator chamber
168
through oil conduit
190
. The addition of a small amount of oil to the fuel of a fuel-injected engine has been found to inhibit the formation of deposits on fuel injectors
154
and to extend their useful life. The addition of oil may also help prevent corrosion when water is present in the system. The oil delivered directly to the combustion chamber with the fuel charge can also help to lubricate the components of the fuel system.
In at least one embodiment, a plurality of oil conduits
151
are provided for delivering oil to a plurality of solenoid valve units
150
which correspond to the number of cylinders
122
in the engine
106
. The oil supply pipes
151
are preferably configured so that their lengths are as short as possible to minimize the distance the oil must travel to the air induction system
132
for each cylinder
122
.
In one preferred embodiment, the oil pump
146
is a positive displacement-type oil pump that is driven by the crankshaft
116
. A positive displacement type oil pump delivers a volume of oil for each crankshaft revolution as opposed to, for example, an impeller-type pump that supplies an approximate pressure of oil based upon engine speed.
The oil delivered through the oil supply pipe
151
is regulated by the solenoid valve unit
150
for delivery into the air intake passage
135
. Preferably, the oil is sprayed into the air intake passage
135
as a mist, such that the oil is carried by the intake air passing through the air intake passage
135
. The air thus carries misted oil into the crankcase chamber
128
and subsequently into the combustion chamber
206
.
With reference to
FIGS. 2 and 3
, the intake silencer
136
includes an opening for allowing intake air to enter therein. The air flows through the intake silencer
136
and is regulated by throttle valves
142
within the throttle body
140
. The air intake passageway
135
is partially defined by a left side part
220
and a right side part
222
that each hold one or more oil delivery pipes
151
. The oil delivery pipes
151
regulate the delivery of oil into the intake air as previously described.
A reed-valve unit
143
comprises a reed valve holder
145
which carries a number of reed valves
144
, which typically correspond in number to the number of engine cylinders. The intake air is drawn through the reed valves
144
and into the crankcase chamber
128
as the piston
124
reciprocates upwardly thereby causing a negative pressure within the crankcase chamber
128
.
The crankshaft
116
is journaled for rotation within the crankcase chamber
118
and has a number of throws
224
each of which are connected to a connecting rod
126
. The connecting rod
126
typically terminates in a semi-circular concave inner peripheral surface that corresponds to a portion of the crankshaft throw
224
. An endcap
226
cooperates with the connecting rod
126
to circumscribe the crankshaft throw
224
.
A plurality of roller bearings
228
are interposed between the interior peripheral surface
230
of the connecting rod
126
and the crankshaft
116
. Alternatively, the connecting rod
126
may engage the crankshaft throw
225
through other means, as are known in the art. The connecting rod
126
opposing end, or small end
230
, is rotatably connected to a piston
124
as previously described.
Referring to
FIGS. 4 and 7
, the crankshaft
116
includes a plurality of webs
234
that cooperate with the cylinder block
121
and crankcase member
130
to separate and substantially seal each crankshaft throw
224
and associated connecting rod
126
within individual portions of the crankcase chamber
128
. The air induction system delivers intake air to each of these individual portions of the crankcase chamber
128
As shown in
FIG. 5
, the reed-type check valve
144
comprises a reed valve unit
143
having a reed valve holder
145
configured to carry a reed
236
. The reeds
236
are biased in a closed position against a frame
238
. In this orientation, the crankcase chamber
128
is closed such that air within the crankcase chamber
128
can be compressed. As the piston
124
moves away from the crankshaft
116
toward its uppermost limit (i.e., top dead center), the volume within the crankcase chamber
128
increases, thereby creating a negative pressure and drawing air into the crankcase chamber
128
from the intake passageway
125
. This air pressure causes the reeds
236
to open away from the frame
238
to thereby allow air to enter the crankcase chamber
128
. The reed's
236
travel limit is defined by a stopper plate
240
attached to the reed-valve holder
145
such as by mounting screws
242
.
Referencing
FIGS. 4-6
, the crankcase bottom wall
244
preferably includes a lubricant guide groove
246
formed therein leading to a lubricant recess
250
. As shown additionally in
FIGS. 2 and 3
, the lubricant recess
250
is semi-circular, and extends around a portion of the perimeter of the crankshaft
116
. The sides of the lubricant recess
250
are defined by an outer sidewall
252
which, in one embodiment, is a substantially vertical portion of the crankcase bottom wall
244
, and by an outer peripheral surface
254
of the crankshaft web
234
forming the inner boundary. In at least one embodiment, the outer peripheral surface
254
of the crankshaft web
234
has a draft angle that inclines away from the center of the lubricant recess
250
, discussed below in greater detail.
The lubricant guide groove
246
extends from approximately below the inner extremity of the reed valve
144
to the lubricant recess
250
and is configured so as to urge lubricant to flow toward the crankshaft
116
. During engine operation, a quantity of oil discharged by the oil delivery pipe
151
deposits on the components within the intake passageway
135
. Such oil deposition occurs more quickly when the mist moves more slowly, such as when the engine is operating at lower speeds, including idling speed. The oil, under gravitational force, will tend to collect at the lower crankcase bottom wall
244
.
Accordingly, the lubricant guide groove
246
is configured to direct this collecting oil to flow toward the lubricant recess
250
. In one embodiment, the lubricant guide groove
246
slopes downwardly toward the lubricant recess
250
to urge the oil to flow in that direction. The oil is further urged through the lubricant guide groove
246
by the intake air. For example, as the piston
124
moves toward the combustion chamber
206
, the intake air is drawn in through the intake passageway
135
and through the reed valve
144
which tends to push the deposited oil along the lubricant groove
246
toward the lubricant recess
250
. Further, as the deposited oil collects in the lubricant recess
250
, it is urged toward the outer peripheral surface
254
of the crankshaft web
234
.
The connecting rod endcap
226
, during a range of its rotational movement, is disposed above, and in close proximity to, the lubricant recess
250
. As such, the connecting rod endcap
226
contacts the collected oil in the lubricant recess
250
. As the crankshaft
116
rotates, a centrifugal force causes the oil deposited on the connecting rod endcap
226
to be thrown around the interior of the crankcase chamber
128
.
Referencing
FIGS. 5 and 8
, the connecting rod
126
has a small end
230
configured for rotatable attachment to a piston
124
. The opposing end includes an endcap
226
formed with one or more oil holes
232
therethrough. The oil holes extend from an inner peripheral surface
256
to an outer peripheral surface
258
of the endcap
226
and permit fluid communication therebetween. In at least one embodiment, the inner peripheral surface
256
of the endcap
226
is directly above the lubricant recess
250
during a range as the crankshaft rotates. This location of the inner oil hole
232
opening facilitates oil draw upwardly into the roller bearing space
262
.
Thus, as the crankshaft
116
rotates, oil that is deposited onto the inner peripheral surface
256
of the endcap
226
flows upwardly into the roller bearing space
262
and is exits the oil hole
232
as shown by the arrows of FIG.
5
. The rotation of the crankshaft
116
causes air turbulence above the lubricant recess
250
and causes the oil deposited within the lubricant recess to flow within the lubricant recess
250
in a direction corresponding to the direction of rotation of the crankshaft.
For example, if the crankshaft
116
rotates in a clockwise direction, the oil within the lubricant recess
250
will tend to flow within the lubricant recess
250
in a clockwise direction and will thus collect toward a clockwise end
260
(
FIG. 3
) of the lubricant recess
250
. Accordingly, there may be a greater volume of oil collecting in this portion of the lubricant recess
250
. As the endcap
226
approaches the clockwise end
260
of the lubricant recess
250
, the available volume for the oil to occupy will be reduced and will thus cause the oil to flow rather than be subjected to compressive forces. The oil will therefore be forced to flow in a counter-clockwise direction within the lubricant recess
250
, or upwardly into the roller bearing space
262
between the endcap
226
and the crankshaft throw
224
. Typically, oil will flow both upwardly into the roller bearing space
262
and within the lubricant recess
250
. The outer peripheral surface
254
of the crankshaft throw
224
further aids the upward flowing of oil into the roller bearing space
262
.
As the oil flows into the roller bearing space
262
, it not only provides a direct lubrication to the roller bearings
228
contained therein, but is also thrown outwardly through the oil holes
232
as the crankshaft
116
rotates and becomes deposited onto the various components within the crankcase chamber
128
, thus providing additional lubrication to the engine components, even during periods of relatively slow operation. Moreover, oil is free to enter the roller bearing space
262
from above the endcap
256
and flow downward to provide further lubrication to roller bearings
228
and be thrown through the oil holes
232
.
In addition to the contact of the endcap
256
directly with the oil in the lubricant recess
250
that causes the oil to flow into the roller bearing space
262
, air pressure also urges the oil to flow upwardly into the roller bearing space
262
. As the crankshaft
116
rotates, even at a slow rpm, such as, for example, 1000 rpm, a pressure differential is created between the inner peripheral surface
256
and the outer peripheral surface
258
of the endcap since a point on the outer peripheral surface
258
is traveling at a greater tangential velocity than a corresponding point on the inner peripheral surface
256
. Thus, according to Bernoulli's principal, the air pressure differential will cause air and oil to flow from the region of relatively higher pressure at the interior peripheral surface
256
of the endcap
226
to the region of lower pressure at the outer peripheral surface
258
of the endcap
226
.
This air pressure differential can also cause air to circulate from within the roller bearing space
262
outwardly through the oil holes
232
. Consequently, the moving air will draw oil from the lubricant recess
250
up into the bearing space
262
which will then be thrown out the oil holes
232
. The drawing of liquid oil from the lubricant recess
250
is further enhanced by the draft angle of the outer peripheral surface
254
of the crankshaft web
234
. As an air flow path is established by the pressure differential, the rushing air will cause oil within the lubricant recess
250
to flow up the incline of the outer peripheral surface
254
and into the roller bearing space
262
where it will flow through the oil holes
232
and be thrown about the crankcase chamber
128
.
Once the oil is thrown throughout the crankcase chamber
128
, it may again collect at the crankcase bottom wall
244
through gravity and be recirculated throughout the crankcase chamber
128
as described herein. Additionally, especially during periods of slower operation when there may be insufficient oil entrained in the intake air, oil thrown around the crankcase chamber
128
may become entrained in the intake air and thus provide increased lubrication to the combustion chamber
206
and related components.
Thus, an improved lubrication system includes a crankcase
130
which may have a lubricant guide groove
246
and/or a lubricant recess
250
formed therein. A connecting rod
126
may include oil holes
232
formed through the connecting rod endcap
226
. At least one embodiment of the improved lubrication system is configured to redistribute oil collecting within the intake passageway
135
and crankcase chamber
128
to the roller bearings
228
and other various components disposed within the crankcase chamber
128
.
Although this invention has been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the invention have been shown and described in detail, other modifications, which are within the scope of this invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.
Claims
- 1. A lubrication system for a two-cycle engine comprising a vertical crankshaft and a lubrication recess disposed generally adjacent to a throw of said crankshaft which opens upwardly such that at least a portion of an endcap of a connecting rod connected to said throw of said crankshaft passes over said recess.
- 2. The lubrication system of claim 1, wherein said lubrication recess is formed in an interior wall of a crankcase of said two-cycle engine.
- 3. The lubrication system of claim 2, further comprising a guide groove extending generally from an air intake of said crankcase to said lubrication recess formed in said interior wall of said crankcase.
- 4. The lubrication system of claim 1, wherein said endcap includes a hole formed therethrough thereby providing an opening in an interior surface of said endcap and an opening in an exterior surface of said endcap.
- 5. The lubrication system of claim 4, wherein said opening in said interior surface of said endcap passes over said lubrication recess during a predetermined range of crankshaft rotation.
- 6. The lubrication system of claim 1, wherein said two-cycle engine is a direct fuel injection engine.
- 7. A two-stroke internal combustion engine comprising one or more cylinders wherein each cylinder has a piston for reciprocation therein, a connecting rod rotatably coupled to each piston and further including an endcap to facilitate coupling of the connecting rod to a throw of a crankshaft, wherein the crankshaft is disposed generally vertically, a lubrication recess disposed adjacent to the crankshaft and generally below a throw of the crankshaft, one or more oil holes formed through the endcap thereby providing fluid communication between an opening in an interior peripheral surface and an opening in an exterior peripheral surface of the endcap, wherein rotation of the crankshaft causes each opening in the interior peripheral surface of the endcap to pass over the lubrication recess.
- 8. The two-stroke internal combustion engine of claim 7, wherein the rotation of the crankshaft causes a pressure differential between the interior surface of the endcap and the exterior surface of the endcap such that oil from within the recess is drawn upwardly and into the interior peripheral surface opening and is thrown through the exterior peripheral surface opening.
- 9. An outboard motor having a powerhead, a driveshaft housing depending from the powerhead, and a lower unit connected to and disposed below the driveshaft housing, the powerhead including an internal combustion engine coupled to a propeller of the lower unit through a driveshaft extending through the driveshaft housing for propelling a watercraft, the internal combustion engine comprising a cylinder block defining a cylinder bore and a cylinder head connected to the cylinder block, the cylinder head further defining a recess in a lower surface thereof, a piston configured for reciprocation within said cylinder bore, wherein a surface of said piston cooperates with the cylinder bore and recess to define a combustion chamber, a crankshaft disposed generally vertically and coupled to the piston through a connecting rod having a large end engaging the crankshaft and a small end engaging the piston, wherein the crankshaft is configured for rotation within a crankcase chamber defined, in part, by a crankcase member, the crankcase member further defining an air intake passageway having a valve disposed therein for regulating the delivery of air and oil to the crankcase chamber, the crankcase member further defining a lubricant recess disposed generally below the large end of the connecting rod during at least a range of the crankshaft rotation and further defining a guide groove configured to urge deposited lubricant to flow toward the lubricant recess, and wherein the large end of the connecting rod draws lubricant from the lubricant recess and throws the lubricant within the crankcase chamber.
- 10. A two-stroke internal combustion engine comprising one or more cylinders wherein each cylinder has a piston for reciprocation therein, a connecting rod rotatably coupled to each piston and further including an endcap to facilitate coupling of the connecting rod to a throw of a crankshaft, wherein the crankshaft is disposed generally vertically within a crankcase chamber, and one or more holes formed radially through the endcap thereby providing fluid communication between a first opening disposed inwardly from an outer peripheral surface and a second opening in the outer peripheral surface of the endcap.
- 11. The two-stroke internal combustion engine of claim 10, further comprising a lubrication recess disposed adjacent the crankshaft and generally below a throw of the crankshaft during at least a range of its rotation.
- 12. The two-stroke internal combustion engine of claim 11, wherein rotation of the crankshaft causes lubricant from within the lubrication recess to be drawn into the first opening and discharged out the second opening.
- 13. The two-stroke internal combustion engine of claim 12, wherein lubricant drawn into the first opening lubricates the coupling between the connecting rod and the crankshaft throw.
- 14. The two-stroke internal combustion engine of claim 12, wherein lubrication is drawn into the first opening by a pressure differential caused by the rotation of the crankshaft.
- 15. The two-stroke internal combustion engine of claim 11, wherein rotation of the crankshaft causes the endcap to splash the lubricant within the lubrication recess thereby forcing lubricant into the first opening.
- 16. The two-stroke internal combustion engine of claim 11, further comprising a guide groove formed in a lower surface of the crankcase and extending generally from an air intake of the crankcase to the lubrication recess.
- 17. A two-stroke internal combustion engine comprising one or more cylinders wherein each cylinder has a piston for reciprocation therein, a connecting rod rotatably coupled to each piston and further including an endcap to facilitate coupling of the connecting rod to a throw of a crankshaft, wherein the crankshaft is disposed generally vertically within a crankcase chamber, and a lubrication recess disposed adjacent to the crankshaft and generally below a throw of the crankshaft.
- 18. The two-stroke internal combustion engine of claim 17, wherein liquid oil within the crankcase chamber collects in the lubrication recess.
- 19. The two-stroke internal combustion engine of claim 18, wherein the endcap and/or connecting rod throw oil from within the lubrication recess about the crankcase chamber.
- 20. An outboard motor having an internal combustion engine with a crankshaft journaled for rotation within a crankcase and coupled to a driveshaft for rotating a propeller connected to the driveshaft, the internal combustion engine comprising means for causing oil to pool adjacent a throw of the crankshaft, and means for redistributing pooled oil around the crankcase.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2001-301620 |
Sep 2001 |
JP |
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5617822 |
Masuda |
Apr 1997 |
A |
5806631 |
Yoshida et al. |
Sep 1998 |
A |
5887678 |
Lavender |
Mar 1999 |
A |