Note: Descriptions are shown in the official language in which they were submitted.
203a908
FUEL FEED SYSTEM
Related Ap~lication
Attention is directed to U.S. application Serial No.
316,153, filed February 27, 1989 and entitled "Internal
Combustion Engine~, and U.S. application S~rial No.
filed , 1990 and entitled Fuel Supply System
Component Assembly" (Attorney's doc~et 72012/0210).
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates generally to fuel feed systems
for internal combustion engines and more particularly to fuel
feed systems including vapor separators.
~eference to the Prior Art
In the prior art, it is generally known to provide a
fuel feed system for an internal combustion engine including a
fuel source and a fuel pump for pumping fuel fro~ the source to
the internal combustion engine. Because fuel for internal
combustion engines is aromatic, fuel vapor easily evaporates
from the fuel. When fuel in a fuel feed system is under
relatively low pressure, excessive amounts of fuel vapor can
form in the fuel feed system prior to introduction of the fuel
to the internal combustion engine.
2 ~ 8
In order to separate accumulated fuel vapor ~rom the
fuel supply prior to introduction of the fuel to the internal
combustion engine, it is generally known to place a fuel vapor
separator downstream of the fuel pllmp and before the
introduction of fuel to the internal combustion engine.
Prior art designs for fuel vapor separators often
;ntroduce difficulty because the fuel vapor separator relies on
negative pressure pulses from the engine to remove fuel vapor
from the supply of fuel. In some applications, the engine is
too small to provide adequate negative pressure pulses to
remove the fuel vapor from the fuel supply.
Attention is directed to the fuel vapor separators
disclosed inithe following U.S. Patents:
4,534,774 LeCoffre et al. August 13,1985
4,450,820 Haynes May 29, 1984
4,315,760 bij de Leij February 16, 1982
4,117,817 Nishida October 3, 1978
4,010,012 Griffin, III et al March 1, 1977
3,985,626 Klein October 12, 1976
3,961,918 Johnson June 8, 1976
3,867,071 Hartley February 18, 1975
3,703,165 Hansen November 21, 1972
3,307,331 Lambert March 7, 1967
2,998,057 Graham August 29, 1961
2,917,110 Brohl December 15, 1959
2,878,889 Gilbert March 24, 1959
2,811,219 Wenzl October 29, 1957
2~3~
2,745,551 Berck May 15, 1956
2,742,049 Granberg April 17, 1956
1,~51,163 Daugherty March 29, 1932
1,804,557 Gould et al. May 12, 1931
1,381,897 Ackley June 21, 1921
1,119,980 Mulligan December 8, 1914
SUMMARY OF T}~E INVENTION
The invention provides a fuel ~eed syste~ for an
;nternal combustion engine, the system including a vapor
separator including a fuel chamber having an inlet and an
outlet and being adapted to contain a supply of fuel, the vapor
separator including means for venting fuel vapor from the
chamber when the supply of fuel is below a predetermined level,
and a vapor pump communicable with the means for venting fuel
vapor and a source of cyclically varying pressure, the vapor
pump including means for pumping fuel vapor from the vapor
separator and to a location remote from said source of
alternating pressure.
In one embodiment of the invention the source of
cyclically varying pressure is a source of alternating positive
and negative pressure, and the vapor pump includes means for
pumping fuel vapor from the fuel chamber when the source
supplies negative pressure and for pumping fuel vapor when the
source supplies positive pressure.
The invention also provides a fuel feed system for an
internal combustion engine, the fuel feed system including a
vapor separator having a fuel reservoir and a cover sealingly
2~3~
engaged with the fuel reservoir to form, with the reservoir, a
fuel chamber adapted for containing a supply of fuel, the vapor
separator including means for venting fuel vapor Erom the fuel
chamber when the supply of fuel in the fuel chamber is below a
predetermined level, and a vapor pump for pumping fuel vapor
from the vapor separator, the vapor pump being located on the
cover and communicable with the means for venting fuel vapor.
The invention also provides a fuel feed system for an
intetnal combustion engine, the system including a fuel pump,
and a vapor separator assembly including a fuel chamber adapted
~or containing a supply of fuel and having an inlet and an
outlet, the assembly including means for venting fuel vapor
from the fuel chamber when the supply of fuel is below a
predetermined level and for pumping fuel from a fuel source to
the assembly independently of the fuel pump.
The invention also provides fuel feed system for an
internal combustion engine, the system including a fuel pump
communicating with the engine, and a vapor separator located
between a fuel source and the fuel pump, the vapor separator
including a fuel chamber adapted to contain a supply of fuel,
and means for venting fuel vapor from the chamber when the
supply of fuel in the chamber is below a predetermined level.
Other features and advantages of the invention will
become known by reference to the following description, and
claims, and the appended drawings.
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DESCRIPTION OF THE DRAWINGS
Figu~e 1 is an elevation view of a fuel feed system
for an internal combustion engine embodying various of the
features of the invention.
Figure 2 is an enlarged rear perspective view,
partially in section, of a portion of the fuel feed system
shown in Figure 1.
Figure 3 is an enlarged side view, partially in
section, of a portion of the fuel feed system shown in Figure 1.
Figure 4 is a sectional view taken along line 4-4 in
Figure 3.
Figure 5 is an enlarged, exploded view, of a portion
of the fuel feed system shown in Figure 2.
Before one embodiment of the invention is explained in
detail, it is to be understood that the invention is not
limited in its application to the details of the construction
and the arrangements of components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced or being
carried out in various ways. Also, it is to be understood that
the phraseology and terminology used herein is for the purpose
of description and should not be regarded as limiting.
DETAILED DESC~IPTION
Shown in Fig. 1 is a fuel supply system 10 for an
internal combustion engine. The fuel supply system 10 is
adapted to supply fuel to at least one carburetor (not shown)
and includes a mounting bracket 14 which supports the following
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fuel system components: a fuel vapor separator 22, a fuel vapor
pump 26, a fuel pump 30, an oil pump 34 (which fuel and oil
pumps can be combined into a combined fuel and oil mixture
pump), a primer fuel control valve 38, and a vacuum switch 42.
While other constructions can be employed, the
mounting bracket 14 is formed of rigid plastic and includes at
least one conduit and portions of the fuel vapor separator 22.
More particularly, the mounting bracket 14 includes a generally
flat base portion 46 which includes four mounting holes 50 and
a reservoir 54 which is part of the fuel separator 22. The
reservoir 54 extends forwardly and rearwardly from the base
portion 46 and is located at the top of the mounting bracket
14~ The reservoir 54 includes a first cylindrical portion 58
which extends `forwardly from the base portion 46 and is open at
the front end 62, and a second box-like portion 66 which
communicates with the cylindrical portion 58 through an opening
68. The box-like portion 66 has an open top 70 which is defined
by a generally rectanqular and flat mounting surface 74.
The open end 62 of the cylindrical portion 58 is
closed by a removable cover or cap 78 which includes an inlet
82 terminating in the form of a nipple 86 connected to an
exterior fuel supply hose 90 adapted to communicate with a
suitable source of fuel. A fuel filter 94 is located within
the cylindrical portion 58 of the reservoir 54.
The mounting bracket 14 also integrally includes an
interior fuel supply conduit or bore 98 which communicates with
the reservoir 54 and which extends thererom interiorly of the
bracket to the bottom of the mounting bracket and terminates in
``` 2~3~9~
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a discharge end or fitting 102. Any suitable arrangement can
be employed interiorl~ of the mounting bracket 14 to provide
the fuel supply conduit or passage 98.
The fuel supply system component asse~bly 10 also
includes means for positively pumping fuel vapor from the fuel
vapor separator 22. While other constructions could be
employed in the disclosed embodiment, the means for positively
p~lmping fuel vapor includes the before mentioned fuel vapor
pump 26 and means for mounting the fuel vapor pump 26 on the
fuel vapor separator 22. While other constructions could be
employed, in the disclosed embodiment the fuel vapor pump 26 is
removably mounted on a reservoir cover member or part 106. The
reservoir cover 106 is fabricated of plastic and includes on
one side, a flat fuel vapor pump mountinq surface 110, and on
another side a flat surface 114 which mates with the flat
mounting surface 7~ on the top of the reservoir 54. The fuel
vapor pump 26 is removably mounted on the mounting surface 110
of the cover member 106 by any suitable means, such as screws.
Wh~n the reservoir cover 106 is removably connected or
assembled on the bracket 14 by any suitable fasteners, as for
instance screws, the cover 106 sealingly closes the open top 70
of the box-like reservoir portion 6~ to complete the fuel
reservoir 54 and define a fuel chamber 116 adapted to contain a
supply of fuel, as well as any fuel vapor which might emanate
from the fuel.
The fuel supply system also includes means for ventin~
fuel vapor from the fuel chamber 54 when the supply of fuel in
the chamber 54 is below a predetermined level, including, in
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the cover member 106 (see figure 3), a fuel vapor passage or
vent 118 which, at one end, communicates with the fuel chamber
115 and which, at the other end (see figure 4), terminates in a
port 122 in the fuel vapor pump mounting surface 110.
The means for venting fuel vapor also includes means
for affording communication between the fuel chamber 54 and the
fuel vapor vent 11~ when the supply of fuel in the fuel chamber
116 is below a predetermined level. While other arrangements
could be used, in the disclosed embodiment, the means for
affording communication between the fuel vapor vent 118 and the
fuel chamber 116 includes a float 126 which is hingedly
supported by the cover member 106 inside the fuel chamber 116
and which is responsive to the level of the supply of fuel in
the fuel chamber 116. In response to the level of fuel in the
fuel chamber, the float 126 moves a valve member 130 relative
to a valve seat 134 located in the fuel vapor vent 118 to
control fuel vapor flow from the fuel separator 22. In this
last regard, when the fuel in the reservoir drops below a
predetermined level, operation of the float 126 permits the
valve member 130 to move away from the valve seat 134 to an
open position, thereby opening the fuel vapor vent 118. When
the fuel in the reservoir rises to the predetermined level, the
float 126 moves the valve member 130 into engagement with the
valve seat 134 thereby preventing passage of fuel vapor into
the vent 118.
While other constructions could be employed, the
fuel vapor pump 26 is provided consequent to assembly of three
disk-like members 138, 142, 196 which, in turn, are assembled
2~3a~
to the cover member by suitable fasteners. The disk-like
members are also assembled together by suitable fasteners, such
as screws. When assembled, the three disk-like members, a
first end disk 138, a second end disk 142, and a middle disk
146 therebetween, form a shell 150 having therein a chamber
152, a fuel vapor inlet 154, a fuel vapor outlet 158, and a
pressure port 16~.
The middle disk 146 and the first end disk 138 define
the chamber 152 therebetween. A diaphragm 166 placed between
the middle disk 146 and the first end disk 138 divides the
chamber 152 into a driving chamber 170 adjacent the first end
disk 138, and a driven chamber 174. In the preferred
embodiment, the diaphragm 166 is made of rubber or some other
flexible, gas impermeable material.
The fuel vapor pump 26 includes means for alternatin~
the pressure in the driving chamber 170. While other
arrangements could be employed, the means for alternating
pressure in the driving chamber includes the pressure port 162
which communicates with the driving chamber 170 and extends
through the first end disk 138 and terminates in the form of a
nipple 178 which is connected to any suitable exterior hose or
conduit 182 which, in turn, is adapted to be connected to a
suitable source of varying cycling or pulsating pressure. In
the disclosed construction, it is contemplated that the
exterior hose 182 will be connected to an engine crankcase.
The fuel vapor inlet 154 communicates at one end with
the driven chamber 174 and extends through the middle disk 146,
the second end disk 142, and a gasket 184 located between the
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middle disk 146 and the second end disk 142, and at another end
mates with the fuel vapor passage port 122 in the mounting
surface 110 of the cover membe~ 106. The vapor pump 26
provides means for affording communication between the fuel
vapor vent 118 and the driven chamber 174 in the form of a
one-way valve 186 located in the fuel vapor inlet 154. The
one-way valve 186 affords communication between the fuel vapor
vent 118, and the driven chamber 174 when the pressure in the
fuel vapor vent 118 is greater than the pressure in the driven
chamber 174 and prevents communication between the fuel vapor
vent 118 and the driven chamber 174 when the pressure in the
driven chamber 174 is greater than the pressure in the fuel
vapor vent 118.
The fuel vapor outlet 158 communicates at one end with
the driven chamber 174 and extends through the middle disk 146,
the gasket 184, and the second end disk 142 and terminates at
another end in the form of a nipple 190 for receiving an
exterior conduit 194 in the form of a hose or tube adapted for
conveying fuel vapor to a suitable point in the engine remote
~rom the source of alternating pressure, as for instance to an
air silencer (not shown).
The vapor pump also provides means for affording
communication between the fuel vapor outlet 158 and the driven
chamber 174 in the form of a second one-way valve 198. The
second one-way valve 198 affords communication between the fuel
vapor outlet 158 and the driven chamber 174 when the pressure
in the driven chamber 174 is greater than the pressure in the
~uel vapor outlet 158 and prevents communication between the
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fuel vapor outlet 158 and the driven chamber 174 when the
pressure in the driven chamber 174 is less than the pressure in
the fuel vapor outlet 158.
The fuel vapor pump also includes means for biasing
the diaphragm 166 in one direction. In the illustrated
embodiment, a spring 202 is provided to bias the diaphragm 166
away from ~he middle disk 146 and toward the first end disk
3~ The middle disk 146 is provided with a seat 206 for the
spring 202. The first end disk 138 includes a metal pad 210
for contacting the diaphragm 166. The means for biasing the
diaphragm 166 also includes a circular plastic member 214 on
the end of the spring 202 adjacent the diaphragm 166 for
protecting the diaphragm 166 from tearing by the spring 202.
Operation of the vapor separator assembly is as
~ollows. During periods of extended inactivity, fuel can drain
from the reservoir 54 in the fuel vapor separator 22 back to a
source of fuel. Upon initiation of operation of the internal
combustion engine, alternating positive and negative pressure
~rom the crankcase initiates operation of the fuel pump 30 and
is introduced to the driving chamber 170 in the fuel vapor pump
26.
As explained below, the fuel pump 30 and the fuel
vapor pump 26 independently draw fuel from the fuel source into
the reservoir 54 through the fuel filter 94. While the supply
of fuel in the reservoir increases, but remains below a
predetermined level, the valve member 130 remains in an open
position to allow the fuel vapor pump 26 to draw fuel vapor and
air from the reservoir 54. The fuel vapor pump 26 removes fuel
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vapor from the reservoir through the fuel vapor vent 118, and
consequently draws fuel from the fuel source into the reservoir
54.
During operation of the internal combustion engine,
both positive and negative pressure pulses act on the driving
chamber 170 to deflect the diaphragm 166. When a negative
pulse acts on the driving chamber 170 through the pressure port
1~2, the negative pressure pulse, and the spring 202 acting on
the diaphragm 166, deflect the diaphragm 166 to enlarge the
driven chamber 174, and thereby create relatively low pressure
in the driven chamber 174. Because of the relatively low
pressure in the driven chamber 174, the one-way valve 186
located between the driven chamber 174 and the fuel vapor
passage port 122 opens to allow air or fuel vapor to be drawn
throuqh the vapor vent 118 into the driven chamber 174 and the
second one-way valve 198 located between the driven chamber 174
and the outlet 158 remains closed to prevent the passage of
fuel vapor.
When the engine provides a pulse of positive pressure,
the driving chamber 170 expands and acts upon the diaphragm 166
and the spring 202 to make the driven chamber 174 smaller. As
the pressure in the driven chamber 174 increases because of its
diminishing size, the one-way valve 186 between the vapor
passage port 122 and the driven chamber 174 closes to prevent
the passage of fuel vapor. During the positive pressure pulse,
relatively high pressure in the driven chamber 174 causes the
second one-way valve 198 between the driven chamber 174 and the
fuel vapor outlet port 158 to open, allowing discharge of fuel
2~3~9~8
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vapor from the driven chamber 17~, through the fuel vapor
outlet port 158, and into the conduit 194 leading to the air
silencer.
As the level of the fuel in the reservoir 54 increases
to a predetermined level, the float 126 rises in response to
the increasing level of fuel and moves the valve member 130
into engagement with the valve seat 13~, preventing passage of
f~lel vapor frGm the reservoir 54 throug~ the fuel vent 118 and
into the vapor pump 26.
During normal operation of the internal combustion
engine, the flow of fuel from the inlet 8~ through the
reservoir 54 and into the conduit 98 continues because of
operation of the fuel pump 30 and is not interrupted by the
~peration of the fuel vapor separator 22. As the pressure of
fuel vapor in the reservoir 54 grows, or upon demand of fuel by
the internal combustion engine greater than the capacity of the
fuel pump 30, the level of fuel in the reservoir 54 will drop.
The float 126 will drop in response to the decreasing level of
fuel and will move the valve member 130 to an open position to
allow passage of fuel vapor through the vent 118 and into the
vapor inlet 154 of the fuel vapor pump. The fuel vapor pump 26
removes fuel vapor from the reservoir 54, consequently
complementing operation of the fuel pump 30 by drawing fuel
into the reservoir 54 until the level of fuel in the reservoir
54 increases to a predetermined lev~l and the float 126 moves
the valve member 130 into engagement with the valve seat 134.
Thus fuel vapor is removed from the fuel vapor
separator 22 using by drawing fuel vapor into the driven
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chamber 174 during negative pressure pulses from the engine and
by expelling fuel vapor from the driven chamber 174 during
positive pressure pulses from the engine. Provision of the
fuel vapor pump 26 in combination with the vapor separator 22
allows removal of fuel vapor from the fuel vapor separator 22
with a minimum pressure head, and allows use of a vapor
separator with smaller engines.
~ urther, during start up of the engine, the vapor pump
~ ~raws air and fuel vapor from the reservoir 54 independently
of operation of the fuel pump 30, increasing the level of fuel
in the reservoir more rapidly than operation of a fuel pump and
a vapor separator without a vapor pump. Also, because both the
fuel pump 30 and the fuel vapor pump 26 draw fuel from a fuel
source, a smaller fuel pump may be used. The vapor separator
can be placed between the fuel pump and the fuel source because
a smaller fuel pump does not introduce zones of low pressure
which result in excessive fuel vapor.
Various of the features of the invention are set forth
in the following claims.
