Note: Descriptions are shown in the official language in which they were submitted.
~20~:~54
TITLE: COMBINED F~UID PP~ESSUP~E
ACTUATED FUEL AND OIL PUMP
INVENTOR: FRANK J. ~JALSWORTH
RELATED APPLICATIONS
This application is a division of my
earlier application Serial No. 413,422, filed
October 14, 1982 and entitled 1'Combined Fluid
Pressure Actuated Fuel and Oil Pump".
BACKGROUND OF T~IE INVENTION
. . _ . _
The invention relates generally to fuel
pumping arrangements.
The invention also generally relates to oil
pumping arrangements.
The invention also relates generally to
fluid pressure actuated motors.
The invention also relates to internal
combustion engines and, more particularly, ~o
two-stroke internal combustion engines and
to means for supplying such engines with a fuel/oil
mixture.
Attention is 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. I.eitermann Patent 3,653,684 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 issuea March 6, 1979, and to the U.S.
Beaton Patent 1,519,478 issued December 16, 1924.
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SUMMARY OF THE INVENTION
. .
The invention provides a fluid pressure
actuated motor comprising a housing, a motor piston
movable reciprocally in the housing and dividing
the housing into a relatively low pressure chamber
and a relatively high pressure chamber, means
biasing the motor piston so as to displace the
motor piston in the direction minimizing the
volume of one of the pressure chambers and ma~imizing
the volume of the other of the pressure chambers,
means for creating a fluid pressure differential
between the high and low pressure chambers so as
to displace the motor piston in the direction
mini~izing the volume of the other pressure chamber
and maximizing the volume of the one pressure
chamber, means response to motor piston movement
minimizing the volume of the other pressure chamber
for establishing com~unication between the high and
low pressure chambers so as thereby to reduce the
pressure differential between the high and low
pressure chambers and thereby permit displacement
of the motor piston by the biasing means in the
direction minimizing the volume of the one pressure
chamber and maximizing the volume of the other
pressure chamber, and means responsive to motor
piston movement minimizing the volu~e of the one
pressure chamber for discontinuing communication
between the high and low pressure chambers so as
to thereby permit the creation of fluid pressure
differential between the high and low pressure
chambers by the fluid pressure differential creating
means and thereby effect displacement of the
motor piston in the direction minimizing the
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volume of the other pressure chamber and maximizing
the volume of the one pressure chamber.
The invention also provides a fluid pressure
actuated motor comprising a housing, a motor
piston movable reciprocally in the housing and
dividing the housing into a relatively low pressure
chamber and a relatively high pressure chamber,
which motor piston includes an output portion~
means biasing the motor piston so as to displace
the motor piston in the direction minimizing the
volume of one of the pressure chambers and
maximizing the volume of the other of the pressure
chambers, means for creating a fluid pressure
differential between the high and low pressure
chambers so as to displace the motor piston in the
direction minimizing the volume of the other pressure
chamber and maximizing the volume of the one
pressure chamber, which means for creating a
pressure differential between the high and low
pressure chambers includes means permitting flow
from the low pressure chamber and preventing flow
to the low pressure chamber, and means permitting
flow to the high pressure chamber and preventing
flow from the high pressure chamber, means
responsive to motor piston movement minimizing
the volume of the other pressure chamber
for establishing communication between the low
and high pressure chambers so as thereby to reduce
the pressure differential between the high and
low pressure chambers and thereby permit displacement
of the motor piston by the biasing means in the
direction minimizing the volume of the one
pressure chamber and maximizing the volume of:the
~o4354
other pressure chamber, and means responsive to
motor piston movement minimizing the volume of
the one pressure chamber for discontinuing
communication between the high and low pressure
chambers so as to thereby permit the creation of
fluid pressure differential between the high and
low pressure chambers by the fluid pressure
differential creating means and thereby effect
displacement of the motor piston in the direction
minimizing the volume of the other pressure
chamber and maximizing the volume of the one
pressure chamber.
In one embodiment in accordance with the
invention, the housing is closed to the atmosphere.
In one embodiment in accordance with the
invention, the means for creating a pressure
differential between the high and low pressure
chambers comprises means adapted to be connected
to a source of alternating relatively high and low
pressures and including means permitting flow from
the low pressure chamber and preventing flow to
the low pressure chamber, and means permitting
flow to the high pressure chamber and preventing
flow from the high pressure chamber.
In one embodiment in accordance with the
invention, the motor also includes pressure relief
means connected between the high and low pressure
chambers to limit the pressure differential there
between.
In one embodiment in accordance with the
invention, the means for establishing and dis-
connecting communication between the high and
low pressure chambers includes a port in the
motor piston, a valve member movable relative to
_5_
the port between open and closed postions, means
biasing the valve member away from the port, and
means on the 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 following general description,
claims and appended drawings.
IN THE DRAWINGS
Fig. 1 is a schematic view of one
embodiment 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.
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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
inve~ntion is not limited in its application to the
detail~ of construction and the arrangement of
components set forth in the following description or
illustrated in the drawings. The invention i5 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.
- / -
5till more particularly, the housing 15
includes a peripheral wall 21, together with a top wall
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
hou~ing 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 fuel 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 45.
The fuel pumping means 19 also includes, in
the peripheral wall 21, a valved fuel outlet 61 which
is adapted to communicate through a conduit 63 with a
device, such as a carburetor 65, for feeding a fuel/oil
mixture to the crankcase 67 of the two-~troke engine 8.
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tne valved outlet 61 includes one-way check valve means
71 which affords outflow o~ 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 ~he
intermediate wall 25. Located in the cylindrical space
87 is an oil pumping plunger or element 91 which
preferably 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
affords inflow of oil in response to an increase in the
volume of the oil pumping chamber 93 and which prevents
outflow of oil.
~Z()435~
g
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 oil outlet 111
com~Fises 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 pumping chamber
93.
The 1uid 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 13 is
responsive to a source of alternating relatively high
and low pressures for effecting reciprocation of the
fuel pumping piston 41 and the oil pumping plunger or
element 91 at a frequency less than the frequency of
the alternation of the relatively hi~h 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,
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relatively low pressure variable volume chamber 123 and
a lower, relatively high pressure variable volume
chamber 125. The movable wall 121 include~ a central
or motor piston 127 which, at its outer periphery, is
connected to a flexible membcane or diaphragm 129
whic~p, 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 portion 131 to the motor piston
127. A suitable seal 139 is providsd between the
intermediate wall 25 and the central portion 131.
The fluid pressure actuated motor 13 further
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 direction minimi~ing 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 ~or connection to a source
of 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 1~3, 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 ic 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 pressureq 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
crea~ing the pressure differential between the
relatively 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 first 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 ~low 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 125
and which prevents flow from the high pressure chamber
1~5.
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 i5 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 1~1 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 in 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
inc~des means responsive to piston movement minimizing
the volume o~ the low pressure chamber 123 foe
establishing communication between the low and high
pressure chambers 123 and 125, respectively, so as
thereby to reduee or minimi7e 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. while such means can ~e
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
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chambers 123 and 12S, respectively, includes a helical
valve member biasing spring 201 which urges the valve
member 193 to the open position and which, at one end,
bears against the upper or top wall 23 of the housing
15 and whi~h, at the other end, extends through the
port l91 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 ove~come 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 mi~imizing the volume of the
low pressure chamber 123.
Means are also provided 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.
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 133 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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15-
of ~he 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 comprLses an
annular flange or ring 213 extending inwardly o~ the
low pressure chamber 123 from the top wall 23 o~ the
hou~ing 15 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
flange 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 a~ the
motor piston 127 approaches the end of the stroke
minimizing 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 ~low 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
displacement 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
discontinuing communication between the low and high
pressure chambers 123 and 125, respectively, so as to
~"0~354
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thereby permit the creation of fluid 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
vol~me 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. As the motor piston 127
approaches the position minimizing the volume of the
low pressure chamber 123~ the va~ve member biasing
spring 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
differential and permit displacement o~ the movable
wall 121 by action of the biasing spring 141 to the
position minimizing the volume of the high pressure
chamber 125. During 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 spriny 201.
Upon approach of the movable wall 121,
including the motor piston 127, to the position
minimizing the volume o~ the high pressure chamber 125,
the studs 221 engage the valve member lg3 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
pumping 41 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
frequency 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 23~ is provided between the
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floating piston 233 and the wall of the subchamber 231.
The floating piston 233 includes, at the outer end
thereof, a portion 237 which extends outwardly of the
subchamber 231 and which is engaged by a cam 239 which
is connected by a suitable linkage 241 shown 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 239 thus variably restricts outward movement of
the floating piston 233 so as to thereby control the
effective pumping stroke o~ the oil pumping plunger 91.
A more detailed description of ~he arrangement for
varying the discharge rate of the oil pumping means 17
can be found in my co-pending Application Serial No.
324,145 which is incorporated herein by reference.
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 tc the engine
crankcase 67 and can be connected to remote sources of
oil and fuel. Alternately, if desired~ the combined
fuel pump and oil pump 11 can be located at a remote
location more or less adjacent to or with the sources
of fuel and oil and a conduit tnot 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 fuel 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 reference numeral have applied for like
components, except for the arrangement for insuring
~0~35~
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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 openin~ movement o the valve member 193
in response to approach of the motor piston 127 to the
posltion 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 211.
Instead, there is provided 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 differential across
the movable 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 ts 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 includes an oil pumping piston 303
which defines, in part, a variable volume oil pumping
chamber 393. The oil pumping piston 303 is slidably
0~
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engaged by the movable element 91 by means o~ 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 pis~on 303 moves
with the movable element 91. Seal ~eans 315 are
provided above a lower end 317 of the piston 303 and
between the lower portion 313 of the pi~ton and the
wall of the cylindrical space 87. The location of the
seal means 315 permi~s the lower end 317 of the piston
to extend below the valve inlet 101 and outlet 319.
In the embodiment, the oil pumpinq means 17
includes a valved outlet 31g 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 pumpinq 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 portioQ 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 32g
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 mean also includes biasing
means for biasing the oil pi~ton 303 toward the
adjustable stop 323. The biasing means comprises a
spring 331 between the upper end 305 of the piston and
the movable element 91 in the central chamber 307.
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 further 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 of oil pumped by the pumping
means.
Shown in Fig. 3 is still another embodiment of
a combined fuel and oil pump 401 which is associated
with the internal combustion engine 8 and which
embodies various of the features o~ 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 for like
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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 127 varies in accordance
with engine speed. In this last regard, the poppet
valve biasinq spring 201 has a spring rate which serves
to open the port l9l prior to the full stroke o~ 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 the engine 8, movement of
the pistoQ relative to the cylinder and crankcase 67
serves to produce in the crankcase, cyclical conditions
of relatively high and low pressures defining a
crankcase pressure amplitude which varies in accordance
with engine speed, i.e., which increases with engine
speed. A~, 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 from about +10 psi to absut -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
~.~0~5~
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pressure chambers 123 and 125, respectively, and the
one-way check valves 169 and 171, the pressure
condition in the low and high pressure chambers 123
and 125, respectively, rapidly reflect the pressures in
the crank~ase 67 an provide a pressure d1fferential
across the movable motor piston 127, i.e., between the
low ~nd high pressure chambers 1~3 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
contraction 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
operate~ 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., is
provided with a stroke which increases in length with
engine speed.
The fuel pumping arrangement employed in the
construc~ion shown in Fig. 3 Yaries from that shown in
Figs. 1 and 2 by placing the valved fuel inlet Sl in
communication with the lower chamber 47 (which is, of
r~4
-2~-
course, not vented). In addition, the fuel pumping
piston 39 is provided with one or more apertures 411,
each having associated therewith a one-way ~heck valve
member 413 affording flow from the lower chamber 47 to
the upper chamber 45 and preventing flow from the upper
chamber 45 to the lower chamber 47. The stroke of fuel
pum~ ng 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 differ~ 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 first 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 stroke. In
this regard, the upper end of the oil pumping piston
303 i~ provided with an axial recess or bore 415 which
i5 defined, at the upper end thereof, by an internal
annular flange 417 defining an opening 419, and the
i~~J~
-25-
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
ups~oke movement of the motor piston 127 from the
position minimiziny the volume of the high pressure
chamber 125 does not cause accompanying movement of the
oil pumping piston 313. However, before the motor
piston 127 reaches the position minimizing the volume
of low pressure chamber 123, the head 423 engages the
flange 417 to cause common movem~nt 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 of the motor piston movement and at the
bottom of the downstroke of the motor piston movement.
Accordingly, the oil pumping arrangement disclosed in
Fi~. 3, provides for 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.
However, if desired, the discharged oil could be
conveyed for mixture with the fuel in either the upper
chamber 45 or in the lower chamber 47.
Various of the features of the invention are
set forth in the following claims.
