Note: Descriptions are shown in the official language in which they were submitted.
TITLE: COMBIN~D FLUID PRESSURE
ACTUA~ED FU~L AND OIL PUMP
I~VENTOR: FRANK J. WALSWORTH
BAC~GROUND OF THE INVENTION
The invention rela~es generally to fuel
pumping arrangements.
The invention also generally relates to oil
pumping arrangement~.
The invention al~o relate~ generally to
1uid pressure actua~ed motors.
The invention also relates to internal
combustion engines and, more particularly, to
two-stroke internal combustion engines and to means
for supplying 6uch e~gines with a fuel/oil mixture.
~ ttention ifi directed to the U.S. Perlewitz
Patent 2,935,057 issued May 30, 1960, to the U.S.
Sparrow Patent 3,481,318 issued December 2~ 1969, to
the U.S. ~eitermann Patent 3,653,6B4 issued April 4.
1972, to the U.S. Shaver Patent 3~913.551 issued
October 21, 1975 to the U.S. Schreier Patent
4,142,486 i~sued March 6, 1979, and to the U.S.
Beaton patent 1,5L9,478 issued December 16, 1924.
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SUMMARY OF THE INVENTIOW
The invention provides a pump compcising
means including a reciprocally movable member ~or
pumping a fluid in response ~o reciprocation of the
member, and motor means connected to the member and
responsive to a source of alternating relatively hiyh
and low pre~sures for effecting reciprocation of the
member at a frequency less than the frequency of the
alternation of the relatively high and low pressures.
The invention also provides a combined fuel
and oil pump comprising means including a
reciprocally movable member foc pumping fuel in
response to reciprocation of the member, means
including a reciprocally movable element for pumping
oil in response to recipeocation of the element, and
mo~or means connected to the member and to the
element and responsive to a source of alternativing
relatively high and low pressures t`or effecting
reciprocation o~ the member and the element at a
frequency less than the frequency of the alternation
of the relatively high and low pressures.
The invention also prov;des a combined fuel
and oil pump comprising means including a
reciprocally movable member for ~umping fuel in
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response to reciprocation of the member, mean~
including a reciprocally movable element for pumping
oil in response to reciproca~ion of the element. and
motor mean~ connected to the member and ~o ~he
element and responsive to a source of alternating
relatively high and low pressures for ef~ecting
reciprocation of the member and the element at a
~requency less than the frequency of the alternation
of the relatively high and low pre~sures, which motor
means includes relatively low and high pressure
chambers which inversely vary in volume, and means
for creating a pressuee differential between the high
and low pressuLe chambers comp~i~ing means adapted to
be connected to a soucce of alternating ralatively
high and low pressures and including means permitting
flow from the low pressure chamber and preventing
flow to the low pressure chamber, and means
permitti.ng flow to the high pressure chamber and
preventing ~low from the high pressure chamber.
In one embodiment in accordance with the
inventLon, the motor pLston, the fuel pumping member
and the oil pump;ng element con6titute an integral
component.
In one embodiment of the invention, the oil
pumping means includes oil discharge means including
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a valved bore extendinq in the component between the
oil pumping chamber and the fuel pumping chamber.
In one embodiment of ~he inventionO the oil
pumping means, the ~uel pumping means, and the motor
means form parts of a single housing.
In one embodiment of the inven~ion, the
movable oil pumping element reciprocates through a
given distance, and the oil pumping means includes
meanR varying ~he output the~eof notwithstanding the
reciprocation of the oil pumping element through the
given distance.
In one embodiment in accordance with the
invention, the means for creating a pressure
d i f f erential between the high and low pressure
chambers comprises means adapted to be connected to a
source of alternativing telatively high and low
pres~ures and including means permitting flow from
the low pressure chamber, and means permitting flow
to the high pre6sure chamber and preventing flow from
the high pressure chamber.
In one embodiment in accordance with the
invention, the motor also includes pressure rQlief
mean~ connected between the high and low pres ure
chambers to limit the pressure differential thare
between.
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In one embodiment i~ accordance with the
invention. the mean~ for establishing and
disconnecting communication between the high and low
pressure chambers includes a port in ~he motor
piston, a valve member movable relative to the port
between open and closed positions, means biasing the
valve member away from the port. and means on ~he
housing engageable with the valve member to close the
port in response to piston movement minimizing the
volume of the high pressure chamber.
Other features and advantages of the
embodiments of the invention will become known by
reference to the followinq general desceiption.
claims and appended drawings.
IN THE DRAWINGS
Fig. 1 is a schematic view of one embodimen~
of a combined fuel and oil pump including a fluid
pressure actuated motor.
Fig. 2 is a schematic view of another
embodiment of a combined fuel and oil pump including
a fluid preSsure actuated motor.
Fig. 3 is a schematic view of still another
embodiment of a combined fuel and oil pump including a
fluid pressure actuated motor.
Before explaining one embodiment of the
invention in detail, it is to be understood that the
invention is not limited in its application to the
details of construction and the arrangement of
components set forth in the following description or
illustrated in the drawings. The invention is capable
of other embodiments and of being practiced and carried
out in various ways. Also, it is to be understood that
the phraseology and terminology employed herein is for
the purpose of description and should not be regarded
as limiting.
GENERAL DESCRIPTION
Shown in the drawings is a marine propulsion
device in the form of an outboard motor 3 which
includes a propulsion unit 5 including a power head 7
incorporating a two-stroke internal combustion engine
8, together with a lower unit 9 which is secured to the
power head 7 and which rotatably supports a propeller
10 driven by the internal combustion engine 8.
Connected to the internal combustion engine 8
is a combined fuel and oil pump 11 including a fluid
pressure motor 13 actuated by a source of alternating
relatively high and low pressures.
More particularly, the combined fuel and oil
pump 11 comprises a housing 15 and, in addition to the
fluid pressure motor 13, includes an oil pumping means
17 and a fuel pumping means 19.
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Still more particularly, the housing ].5
includes a peripheral wall 21, together with a top ~all
23, an intermediate wall or partition 25, a bottom wall
27, and a lower extension 29. The intermediate wall 25
includes a central bore or port 31 and divides the
housing 15 into an upper compartment 33 and a lower
compartment 35.
The fuel pumping means 19 includes a movable
wall or member 39 which is located in the lower
compartment 35 and which divides the lower compartment
35 into a variable volume fuel pumping chamber 45
located between the intermediate wall 25 and the fuel
pumping piston or movable wall or member 39 and a lower
or vent chamber 47 which communicates with the
atmosphere through a port 49 in the bottom wall 27.
The movable wall or member 39 includes a piston 41
which, at its periphery, has attached thereto a
flexible membrane or diaphragm 43 which, in turn, is
attached -to the peripheral wall 21 of the housing 15.
The fuel pumping means 19 also includes, in
the peripheral wall 21, a valved fuel inlet 51 which is
adapted to communicate through a conduit 53 with a
suitable source 55 of fuel and which includes one-way
check valve means 57 affording inflow of Euel in
response to an increase in the volume of the fuel
pumping chamber 45 and which prevents outflow of fuel
from the fuel pumping chamber ~5.
The fuel pumping means 19 also includes, in
the peripheral wall 21, a valved Euel outlet 61 which
is adapted to communicate through a conduit 63 with a
device, such as a carburetor 65, for feeding a fuel/o.il
mixture to the crankcase 67 of the two-stroke engine 8.
23
the valved outlet 61 includes one~way check valve means
71 which affords outflow of fuel in response to a
decrease in the volume of the fuel pumping chamber 45
and which prevents inflow of fuel.
Preferably, the conduit 63 includes an
accumulator 75 in the form of a cylinder 77 which, at
one end, communicates with the conduit 63 and which, at
the other or outer end, is vented to the atmosphere by
a port 79. Located in the cylinder 77 is a piston 81
which is suitably biased by a spring 83 in the
direction toward the conduit 63 so as to provide a
variable volume accumulating chamber 85 which serves to
reduce or eliminate pulsing of fuel at the discharge
end of the conduit 63.
The oil pumping means 17 is located in the
lower extension 29 and comprises a cylindrical space 87
which extends from the vent chamber 47 in generally
aligned relation to the central port 31 in the
intermediate wall 25. Located in the cylindrical space
87 is an oil pumping plunger or element 91 which
preEerably extends integrally from the fuel pumping
piston 41, which is reciprocal in the cylindrical space
87, and which, in part, defines a variable volume oil
pumping chamber 93. Seal means 95 is provided between
the oil pumping plunger or element 91 and the wall of
the cylindrical space 87.
The oil pumping means 17 also includes a
valved inlet 101 which is adapted to communicate
through a conduit 103 with a source 105 of oil and
which includes one-way check valve means 107 which
a.EEords inflow of oil in response to an increase in the
volume o~ the oil pumping chamber 93 and which prevents
outflow of oil.
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The oil pumping means 17 also includes a valve
outlet 111. While various other arrangements can be
employed, in the illustrated construction, the outlet
111 is designed to deliver oil to the fuel pumping
chamber 45. More particularly, the oi.l outlet 111
comprises a bore 113 which extends axially in the oil
pumping plunger or element 91, which, at one end,
communicates with the oil pumping chamber 93, which, at
the other end, includes one or more radial branch ports
115 which communicates with the fuel pumping chamber
45, and which includes, intermediate the inlet 101 and
the outlet 111, an enlarged central portion 117 having
a one way check valve means 119 which affords outflow
of oil to the fuel pumping chamber 45 in response to a
decrease in the volume of the oil pumping chamber 93
and which prevents inflow into the oil p-lmping chamber
93.
The fluid pressure actuated motor 13 is
located generally in the upper compartment 33 and is
connected to the oil pumping plunger 91 and to the fuel
pumping piston 41 so as to effect common reciprocation
thereof through a given stroke or distance. More
particularly, the fluid pressure actuated motor 1.3 is
responsive to a source of alternating relatively high
and low pressures for effecting reciprocation of the
fuel pumping piston ~1 and the oil pumping plunger or
element 91 at a frequency less than the frequency of
the alternation o~ the relatively high and low
pressures. Still more particularly, the fluid pressure
actuated motor 13 includes a movable wall 121 which
divides the upper compartment 33 into an upper,
relatively low pressure variable volume chamber 123 and
a lower, relatively high pressure variable volume
chamber 125. The movable wall 121 includes a central
or motor piston 127 which, at its outer periphery, is
connected to a flexible membrane or diaphragm 129
which, at its outer periphery, is secured to the
peripheral housing wall 21 so as to divide the upper
compartment 33 into the before-mentioned relatively low
and high pressure chambers.
The central motor piston 127 is also
preferably integrally connected with the fuel pumping
piston 41 and with the oil pumping plunger or element
91 for common movement. In this last regard, the
combined motor piston 127, fuel pumping piston 41, and
oil pumping plunger 91 includes a central portion 131
which extends from the fuel pumping piston 41 toward
the motor piston 127 and through the central bore or
port 31 in the intermediate wall 25, and a connecting
portion which forms an open valve cage 135 and which
connects the central 131 to the motor piston
127. A suitable seal 139 is provided between the
intermediate wall 25 and the central portion 131.
The fluid pressure actuated motor 13 furthur
includes means biasing the movable wall 121 so as to
displace the movable wall 121 in the direction
minimizing the volume of the high pressure chamber 125
and maximizing the volume of the low pressure chamber
123. In the illustrated construction, such means
comprises a helical spring 141 which, at one end, bears
against the upper or top housing wall 23 and which, at
the other end, bears against the motor piston 127.
The fluid pressure actuated motor 13 also
includes means 151 for creating a pressure differential
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between the low and high pressure chambers 123 and 125,
respectively, so as to displace the movable wall 121 in
the dire~tion minimizing the volume of the low pressure
chamber 123 and maximizing the volume of the high
pressure chamber 125. While various arrangements can
be employed, in the illustrated construction, such
means includes means adapted for connection to a source
oE alternating relatively high and low pressures and
including means permitting flow from the low pressure
chamber 123 and preventing flow to the low pressure
chamber 123, and means permitting flow to the high
pressure chamber 125 and preventing flow from the high
pressure chamber 125.
Preferably, the source of alternating
relatively high and low pressures is the crankcase 67
of the two-stroke engine 8. However, other sources of
relatively high and low pressures can be employed. In
addition, relatively high and low pressure can refer to
two positive pressures above atmospheric pressure, to
two negative pressures below atmospheric pressure, or
to one positive pressure above atmospheric pressure and
one negative pressure below atmospheric pressure.
Still more specifically, the means 151 for
creating the pressure differential between the
relati.vely low and high pressure cylinders 123 and 125,
respectively, also includes a conduit system 161
including a main conduit 163 adapted to be connected to
the source of alternating high and low pressures, such
as the crankcase 67 of the two-stroke engine 8,
together with a Eirst or low pressure branch conduit
165 which communicates between the low pressure chamber
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123 and the main conduit 163 and a second or high
pressure branch conduit 167 which communicates between
the high pressure chamber 125 and main conduit 163.
Included in the low pressure branch conduit
165 is a one-way check valve 169 which permits flow
from the low pressure chamber 123 and prevents Elow to
the low pressure chamber 123. Located in the high
pressure branch conduit 167 is a one way check valve
171 which permits flow to the high pressure chamber 1~5
and which prevents flow from the high pressure chamber
125.
Accordingly, alternating pressure pulses of
relatively high and low pressures present in the main
conduit 163 will cause the existence of a relatively
high pressure in the high pressure chamber 125 and a
relatively low pressure in the low pressure chamber
123, which pressure differential is of sufficient
magnitude, as compared to the biasing action of the
movable wall biasing spring 141, so that the pressure
differential is effective to cause movement of the
movable wall 121 from a position in which the high
pressure chamber 125 is at a minimum volume to a
position in which the low pressure chamber 123 is at a
minimum volume.
Preferably, the conduit system 161 also
includes means for relieving an excessive pressure
differential. In this regard, the conduit system 161
includes a bypass conduit 175 which communicates with
the low and high pressure branch conduits 165 and 167,
respectively, so as to be i~ direct communication with
the low and high pressure chambers 123 and 125,
respectively. The bypass conduit 175 includes a one-way
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pressure regulating valve 177 including a ball member
179 which is engaged with a seat 181 and held in such
engagement by spring 183 designed to release the ball
member 179 from engagement with the seat 181 in the
event of an excessive differential pressure.
The fluid pressure actuated motor 13 also
includes means responsive to piston movement minimi~ing
the volume of the low pressure chamber 123 for
establishing communication between the low and high
pressure chambers 123 and 125, respectively, so as
thereby to reduce or minimize the pressure differential
between the low an high pressure chambers 123 and 125,
respectively, and thereby permit displacement of the
movable wall 121 by the biasing spring 141 in the
direction minimizing the volume of the high pressure
chamber 125 and maximizing the volume of the low
pressure chamber 123. ~hile such means can be
provided, at least in part, by a conduit (not shown)
bypassing the motor piston 127, in the illustrated
construction, such means comprises a central port 191
in the motor piston 127, together with a valve member
193 which is located in the open cage 135 of the
combined motor piston 127, fuel pumping piston 41 and
oil pumping plunger 91, and which is movable between a
closed and an open position. Preferably, the valve
member 193 includes a downwardly extending stem 195
which is received in a mating recess or axial bore 197
in the central portion 131 of the combined piston so as
to guide movement of the valve member 193 between its
open and closed positions.
In addition, the means for effecting
communication between the low and high pressure
chambers 123 and 125l respectively, includes a helical
valve member biasing spring 201 which urges the valve
member 193 ~o the open position and which, at one end,
bears against the upper or top wall 23 of the housing
15 and which, at the other end, extends through the
port 191 in the motor piston 127 and bears against the
upper surface of the valve member 193. The valve
member biasing spring 201 is designed so as to be
operable to overcome the pressure differential between
the low and high pressure chambers 123 and 125,
respectively, and thereby to displace the valve member
193 toward the open position as the motor piston 127
approaches the position minimizing the volume of the
low pressure chamber 123.
Means are also provided for insuring full
opening movement of the val.ve member 193 in response to
approach of the motor piston 127 to the position
minimizing the volume of the low pressure chamber 123.
Such means is provided in the low pressure chamber 123
and comprises means defining an intermediate chamber
211 communicating with the motor piston port 191 and
providing resistance to flow from the intermediate
chamber 211 to the low pressure chamber 123 upon
initial opening of the valve member 193 so as thereby
to effect reduction in the pressure differential
between the high pressure chamber 125 and the
intermediate chamber 211 and thereby to cause movement
of the valve member 193 to the full opened position.
Such movement substantially reduces the pressure
differential between the low pressure chamber 123 and
the high pressure chamber 125, and thereby permits
movement of the movable wall 121 to minimize the volume
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of the high pressure chamber 125 in response to the
action of the motor piston biasing spring 141. While
various arrangements can be employed, in the
illustrated construction, such means comprises an
annular flange or ring 213 extending inwardly of the
low pressure chamber 123 from the top wall 23 o the
housing lS and in radially outward relation from the
valve member biasing spring 201 and in radially inward
relation from the motor piston biasing spring 141. In
addition, such means comprises a cooperating annular
1ange or ring 215 extending from the motor piston 127
toward the housing top wall 23 and movable into
telescopic relation to the flange or ring 213 as the
motor piston 127 approaches the end of the stroke
minimi%ing the volume of the low pressure chamber 123
so as to telescopically form the intermediate chamber
211 and to provide resistance to flow from the
intermediate chamber 211 to the low pressure chamber
123.
Such resistance to flow between the
intermediate chamber 211 and the low pressure chamber
123 causes deminishment in the resistance to flow or
pressure drop between the high pressure chamber 125 and
the intermediate chamber 211, thereby assuring action
of the valve member biasing spring 201 to effect
di.splacement of the valve member 193 to its fully open
position.
The fluid pressure actuated motor 13 also
includes means responsive to piston movement minimizing
the volume of the high pressure chamber 125 for
disconti~uing communication between the low and high
pressure chambers 123 and 125, respectively, so as to
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thereby permit the creation of Eluid pressure
differential between the low and high pressure chambers
123 and 125 by the fluid pressure differential creating
means and thereby also to effect displacement of the
motor piston 127 in the direction minimizing the volume
of the low pressure chamber 123 and maximizing the
volume of the high pressure chamber 125. While other
arrangements can be employed, in the illustrated
construction, such means comprises a plurality of studs
or posts 221 which extend upwardly from the
intermediate partition or wall 25 toward the valve
member 193 and through the open valve cage 135 for
engagement with the valve member 193 to seat the valve
member 193 in the closed position as the motor piston
127 approaches the position minimizing the volume of
the high pressure chamber 125.
Thus, in operation, the presence of
alternating high and low pressures in the conduit
system 161 causes (assuming the valve member 193 to be
in the closed position) buildup and maintenance of
higher pressure in the relatively high pressure chamber
125 and reduction and maintenance of low pressure in
the low pressure chamber 123. The pressure
differential thus created causes displacement of the
movable wall 121, including the motor piston 127,
against the action of the motor piston biasing spring
141, to the position minimizing the volume of the low
pressure chamber 123. ~s the motor piston 127
approaches the position minimizing the volume of the
low pressure chamber 123, the valve member biasing
spri.ng 201 serves to open the motor piston port 191 by
displacing the valve member 193 to the open position
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and thereby to reduce or minimize the pressure
diEferential and permit displacement of the movable
wall 121 by action of the biasing spring 141 to the
position minimizing the volume of the high pressure
chamber 125. Duriny such movement, and in the absence
of a pressure differential, the valve member 193
remains in the open position under the action of the
valve member biasing spring 201.
~ pon approach of the movable wall 121,
including the motor piston 127, to the position
minimiæing the volume of the high pressure chamber 125,
the studs 221 engage the valve member 193 to cause
movement thereof to the closed position. With the
motor piston port 191 thus closed, the pressure
differential is again created and the movable wall 121
is again displaced in the opposite direction to
commence another cylce of operation. As the fuel
pumpiny ql and the oil pumping plunger 91 have common
movement with the motor piston 127, the fluid actuated
motor 13 causes reciprocation of these components at a
Erequency less than the frequency exciting the motor
13, i.e., less than the rate of alternation of the high
and low pressures in the source.
Preferably, means are provided for selectively
adjusting the discharge rate of the oil pumping means
17, notwithstanding displacement of the oil pumping
plunger 91 through a generally constant stroke. While
various other arrangements can be employed, in the
illustrated construction, such means comprises a
subchamber 231 which extends from the oil pumping
chamber 93 and which includes therein a floating piston
233. A suitable seal 235 is provided between the
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floating piston 233 and the wall of the subchamber
231. The floating piston 233 includas, at the outer
end th~reof, a portion 237 which extends vu~wardly of
the subchamber 231 and which is engaged by a cam 239
which is connected by a suitable linkage 241 ~hown in
dotted outline to the engine throttle 243 and which
is, accordingly, selectively positionable in
accordance with selective positioning of the engine
throttle 243. The cam 2~9 thus variably restricts
outward movement of the floating pifiton 233 so as to
thereby control the e~fective pumping stroke of the
oil pumping plunger 9L. A more detailed description
of the arrangement for varying the di~charge rate of
the oil pumping means 17 can be found in my
co-pending Canadian Application Serial No. 406,927
eiled July a. 1982.
The combined fuel and oil pumping device 11
can be mounted to the block of the two-stroke engine
8 so as to afford immediate connection to the engine
crankcase 67 and can be connected to remote soueces
of oil and fuel. ~lternately~ if desired, the
combined fuel pump and oil pump 11 can be locatsd at
a remote location more or less adjacent to or with
the sources of fuel and oil and a conduit (not shown~
can extend between the crankcase 67, or other source
of alternating high and low pressures, and the
combined fuel and oil pumping device 11.
Shown in Fig. 2 is another embodiment of a
combined euel and oil pump 301 in accordance with the
invention. The construction shown in Fig. 2 is
generally identical to that shown in Fig. 1, and the
same referece numeral have applied for like
components, except for the arrangement for insuring
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full opening of the valve member 193 and the
arrangement for varying the amount of oil flow and the
oil discharge arrangement.
With respect to the arrangement or means for
insuring full opening movement of the valve member 193
in response to approach of the motor piston 127 to the
position minimizing the volume of the low pressure
chamber 123, in the construction illustrated in Fig. 2,
the rings 213 and 215 have been omitted, thereby also
omitting provision of the intermediate chamber ~11.
Instead, there is pro~ided a member or post 302 which
fixedly depends downwardly from the top housing wall 23
in position for engaging the valve member 193 as the
movable wall 121 minimizes the volume of the low
pressure chamber 123. Such engagement causes
"cracking" or slight opening of the port 191, thereby
somewhat diminishing the pressure diEferential across
the rnovable wall 121. Such diminishment of the
pressure differential facilitates immediately
subsequent operation of the poppet valve member biasing
spring 201 to displace the valve member 193 so as to
fully open the port 191 and thereby to substantially
eliminate the pressure differential and obtain wall
movement in the direction minimizing the volume of the
high pressure chamber 125 under the action of the
movable wall biasing spring 141. It is also noted that
the post 302 serves to stabilize or locate the upper
end of the poppet valve member biasing spring 201.
In the embodiment shown in Fig. 2, the oil
pumping arrangement inc].udes an oil pumping piston 303
which defines, in part, a variable volume oil pumping
chamber 393~ The oil pumping piston 303 is slidably
engaged by the movable element 91 by means of an upper
end 305 of the piston 303 being located in an enclosed
central chamber 307 in the movable element 91. A mid
portion 309 of the piston 303 extends outwardly of the
chamber 307 through an opening 311 and connects the
upper end 305 of the piston 303 to a lower portion 313
in the cylindrical space 87. The upper end 305 of the
piston 303 is larger than the opening 311 so when the
movable element 91 moves upwardly, the piston 303 moves
with the movable element 91. Seal means 315 are
provided above a lower end 317 of the piston 303 and
between the lower portion 313 of the piston and the
wall of the cylindrical space 87. The location of the
seal means 315 permits the lower end 317 of the piston
to extend below the valve inlet 101 and outlet 319.
In the embodiment, the oil pumping means 17
includes a valved outlet 319 which extends coaxially
with the valved inlet 101 but on the opposite side of
the cylindrical space 87. The outlet 319 includes a
one way check valve 321 and affords outflow of oil to
the conduit 63 for feeding the oil to the carburetor 65.
In the embodiment shown in Fig. 2, the means
for selectively adjusting the discharge rate of the oil
pumping means includes an adjustable stop 323 which
defines, in part, the oil pumping chamber 393. The
adjustable stop 323 is located in the cylindrical space
87 below the inlet 101 and outlet 319. A suitable seal
325 is provided between the adjustable stop 323 and the
wall of the cylindrical space 87, and a portion 327 of
the adjustable stop above the seal 325 has a diameter
less than the diameter of the cylindrical space 87 to
permit the upper portion 327 of the adjustable stop to
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extend above the inlet 101 and outlet 319. The lower
end of the adjustable stop 323 includes a portion 329
which extends outwardly of the cylindrical space 87 and
which is engaged by the cam 239. The cam 239 operates
as previously described.
The oil pumping means also includes biasing
means for biasing the oil piston 303 toward the
adjustable stop 323. The biasing means comprises
spring 331 between the upper end 305 of the piston and
the movable element 91 in the central chamber 30~.
In operation, as the movable element 91 moves
downward, the oil piston 303 moves downwardly an equal
distance. The biasing means or spring 331 is preloaded
so that it will not deflect due to either oil pump
pressure or seal friction. As the piston 303 moves
downwardly, the oil pumping chamber 393 will be reduced
in volume and will force oil out through the valved
outlet 319. However, when the oil piston 303 contacts
the adjustable stop 323, it will move no Eurther and
the remaining stroke of the movable element 91 will be
taken up or lost by deflecting the biasing means or
spring 331. The location of the adjustable stop 323
will, therefore, vary the volume of the oil pumping
chamber 393 and the amount oE oil pumped by the pumping
means.
Shown in Fig. 3 is still another embodiment of
a combined fuel and oil pump 401 which is associa-ted
with the internal combustion engine 8 and which
embodies various of the features of the invention. The
construction shown in Figure 3 is generally identical
to the construction shown in Figure 2 and the same
reference numerals have been applied Eor like
components, except that the fuel pumping arrangement
has been slightly modified, except that the oil pumping
arrangement has been modified to provide for variation
in the output of the oil pump in accordance with engine
speed without use of a movable part 239 or element 323
and associated linkage, and except that the one-way
pressure-regulating valve 177 has been omitted and the
stroke of the motor piston 1~7 varies in accordance
with engine speed. In this last regard, the poppet
valve biasing spring 201 has a spring rate which serves
to open the port 191 prior to the full stroke of the
motor piston 127 when the engine 8 is operating at low
speed and which serves to open the port 191 upon
completion of the full stroke of the motor piston 127
when the engine 8 is operating at high speed.
More particularly, as is well known, in a
two~stroke engine, such as ~he engine 8, movement of
the piston relative to the cylinder and crankcase 67
serves to produce in the crankcase, cyclical conditions
of relativel~ high and low pressures definlng a
crankcase pressure amplitude which varies in accordance
with engine speed, i.e., which increases with engine
speed. As, for example, when engine operation is at
idle or low speed, the pressures in the crankcase can
vary from about ~3 psi to about -3 psi, thus providing
a crankcase pressure amplitude of 6 psi. Also, for
example, when operating at high engine speed, the
pressure in the crankcase can vary from about ~5 psi to
-6 psi, or Erom about +10 psi to about -1 psi, thus
providing a crankcase pressure amplitude of 11 psi.
Under operating conditions, because of the
connection of the crankcase 67 to the low and high
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pressure chambers 123 and 125~ respectively, and the
one-way check valves 169 and 171, the pressure
conditions in the low and high pressure chambers 123
and 125, respectively, rapidly reflect the pressures in
the crankcase ~7 an provide a pressure differential
across the movable motor piston 127, i.e., between the
low and high pressure chambers 123 and 125,
respectively, which pressure differential has an
amplitude approximating the crankcase pressure
amplitude.
The poppet valve biasing spring 201, as
already indicated, has a spring rate such that partial
movement of the motor piston 127 between the positions
causing minimum volume of the low and high pressure
chambers 123 and 125, respectively, will cause such
contractlon of the poppet valve biasing spring 201 as
to overcome the force on the valve member 193 occurring
in response to the pressure differential when the
engine 8 is operating at low speed. However, the
spring rate is such that, whenever the engine 8
operates at high speed, the force created by the
pressure differential is sufficiently great to provide
greater travel or full travel of the movable wall 121
or motor piston 127 prior to opening of the port 191.
As a consequence, the motor piston 127 is provided with
a stroke which varies with engine speed, i.e., i5
provided with a stroke which increases in length with
engine speed.
The fuel pumping arrangement employed in the
construction shown in Fig. 3 varies from that shown in
Figs. 1 and 2 by placing the valved fuel inlet 51 in
communication with the lower chamber 47 tWhich is, of
Z3
course, not vented). In addition, the Euel pumping
piston 39 is provided with one or more apertures 411,
each having associated therewith a one-way check valve
member 413 affording flow rom the lower chamber 47 to
the upper chamber 45 and preventing flow ~rom the upper
chamber 45 to the lower chamber 47. The stroke of fuel
pumping member or piston 39 is identical to the stroke
of the motor piston 127 and hence the amount of fuel
pumped will vary in accordance with engine speed, i.e.,
will increase with increasing engine speed.
If desired, a fuel pump construction
identical to that shown in Figs. 1 and 2 could also
be employed.
The oil pumping arrangement diEfers from the
construction shown in Figs. 1 and 2. in that the amount
of oil pumped is automatically varied in accordance
with engine speed and in that, due to a lost-motion
connection between the motor piston 127 and the oil
pumping piston 303, oil pumping does not occur until
after a Eirst engine speed level~ which can be
intermediate the low and high engine speeds, and which,
above the first engine speed level, increases with
increasing engine speed.
In this last regard, the oil pumping piston
303 is connected to the motor piston 127 to provide for
common movement therewith during a portion of the motor
piston stroke and to provide for lost-motion during
another portion of the motor piston 127 strokeO In
this regard, the upper end of the oil pumping piston
303 i3 provided with an axial recess or bore 415 which
is defined, at the upper end thereof, by an internal
annular flange 417 defining an opening 419, and the
motor piston 127 is provided with an extension 421
which projects through the opening 419 provided by the
annualar flange 417 and includes~ at the lower end, an
enlarged head 423 which cannot pass through the opening
419 defined by the annualar flange 417. Thus, initial
upstroke movement of the motor piston 127 from the
position minimizing the volume of the high pressure
chamber l~S does not cause accompanying movement of the
oil pumping piston 313. However, before the motor
piston 127 reaches the position minimizing the volume
o~ low pressure chamber 123, the head 423 engages the
flange 417 to cause common movement of the oil pumping
piston 303 with the motor piston 127. Initial
downstroke motion of the motor piston 127 does not
cause the oil pumping piston movement until the head
423 engages the blind end of the recess or bore 415.
Thus, oil pumping operation occurs only at the top of
the upstroke o~ the motor piston movement and at the
bottom of the downstroke of the motor piston movement.
Accordingly, the oil pumping arrangement disclosed in
Fig. 3, provides ~or little or no pumping at low engine
speeds and for increasing oil pumping with increasing
speeds above low engine speed.
As in the construction shown in Fig. 2, the
oil discharge from the output 319 is conveyed to the
fuel discharge conduit 63 for mixture therewith.
~Iowever, i~ desired, the discharged oil could be
conveyed Eor mixture with the fuel in either the upper
chamber ~5 or in the lower chamber 47.
Various of the features of the invention are
set forth in the following claims.
