U.S. patent number 3,752,134 [Application Number 05/241,350] was granted by the patent office on 1973-08-14 for vapor regulating valve.
This patent grant is currently assigned to General Motors Corporation. Invention is credited to Thomas J. Hollis, Jr..
United States Patent |
3,752,134 |
Hollis, Jr. |
August 14, 1973 |
VAPOR REGULATING VALVE
Abstract
A vapor regulating valve for use in a system for mixing air with
fuel tank vapor stored in a fuel tank, the valve being constructed
so that fuel tank vapor pressure applied against a diaphragm raises
a metering valve to control the flow of fuel vapor and air to the
intake manifold of an internal combustion engine. A second
diaphragm responsive to engine intake manifold vacuum is used to
effect the opening and closing of a valve to control the flow of
fuel vapor as a function of engine operating conditions.
Inventors: |
Hollis, Jr.; Thomas J.
(Fairport, NY) |
Assignee: |
General Motors Corporation
(Detroit, MI)
|
Family
ID: |
22910366 |
Appl.
No.: |
05/241,350 |
Filed: |
April 5, 1972 |
Current U.S.
Class: |
123/520 |
Current CPC
Class: |
F02M
25/0836 (20130101) |
Current International
Class: |
F02M
25/08 (20060101); F02d 019/00 () |
Field of
Search: |
;123/136,120 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Goodridge; Laurence M.
Assistant Examiner: Flint; Cort
Claims
What is claimed is:
1. In a vapor recovery system for an internal combustion engine
having an induction system and a fuel reservoir, a vapor regulating
valve including a housing having an inlet means connectable to the
fuel reservoir for receiving fuel vapor discharge from the fuel
reservoir, an air inlet means, and an outlet means connected to the
induction system for delivering a mixture of fuel vapor and air to
the induction system, a valve mechanism disposed between said
outlet means and said inlet means and said air inlet means for
controlling the flow of fuel vapor and air from both said inlet
means to said outlet means, spring means biasing said valve
mechanism to prevent flow of fuel vapor and air from said inlet
means to said outlet means and pressure means responsive to the
pressure in said fuel reservoir and connected to said valve
mechanism whereby said first valve mechanism is operated to control
the rate of flow of fuel vapor and air from said inlet means to
said outlet means in accordance with the pressure of the fuel vapor
in said fuel reservoir, a diaphragm valve disposed between said
inlet means and said valve mechanism for controlling the flow of
fuel vapor to said outlet means as controlled by said first valve
mechanism, second spring means biasing said diaphragm valve to shut
off fuel vapor flow from said inlet means and means responsive to
the pressure in said induction system and operatively connected to
said diaphragm valve whereby said diaphragm valve is operated to
control the flow of fuel vapor from said inlet means toward said
outlet means in accordance with the vacuum pressure in the
induction system as affected by the operating conditions of the
internal combustion engine.
2. A vapor regulating valve for use in a fuel vapor recovery system
for an internal combustion engine having an intake manifold and a
fuel reservoir, said vapor regulating valve including a valve
housing having a first passage means therein including a first
inlet for fuel vapor connectable to the fuel reservoir, a second
passage means including an air inlet connectable with a source of
atmospheric air and a third passage means therein including an
outlet connectable to the intake manifold of the engine, a first
valve movable in said first passage means between an open position
and a closed position, first valve operating means including a
pressure responsive diaphragm in said housing to form first and
second chambers on opposite sides of said diaphragm with said
diaphragm being positioned to engage said first valve whereby said
first valve may be closed by actuating said diaphragm, said first
chamber being connectable to the intake manifold and said second
chamber being open to the atmosphere, a second valve positioned in
said housing and movable between an open position and a closed
position to control the flow from said first passage means and said
second passage means to said third passage means, second valve
operating means including a second pressure responsive diaphragm in
said housing to form a chamber therein in communication with said
first passage means between said first valve and said second valve
and means operatively connecting said second diaphragm and said
second valve whereby said second valve is positioned by said
diaphragm.
3. A vapor regulating valve according to claim 2 wherein a first
spring means is positioned in said first chamber in operative
relation to said first diaphragm to normally bias said first valve
to said closed position.
4. A vapor regulating valve according to claim 3 wherein said first
valve is a diaphragm type valve with a portion of one side thereof
in communication with said first inlet and responsive to fuel vapor
pressure in the fuel reservoir to effect movement of said first
valve to said open position.
5. A vapor regulating valve according to claim 2 including a second
spring means in said housing positioned in operative relation to
said second diaphragm to normally bias said second valve to said
closed position.
6. A vapor regulating valve for controlling the loss of fuel vapor
from a unit having a fuel reservoir and an internal combustion
engine with an induction system, said vapor regulating valve
including a housing means having a fuel vapor inlet means
connectable to the fuel reservoir for receiving fuel vapor
discharge from the fuel reservoir, an air inlet means, an outlet
means connectable to the induction system for delivering a mixture
of fuel vapor and air to the induction system, a first valve
mechanism disposed between said outlet means and said fuel vapor
inlet means and said air inlet means for controlling the flow of
fuel vapor and air from both said inlet means to said outlet means,
spring means biasing said valve mechanism to prevent flow of fuel
vapor and air from said inlet means to said outlet means,
differential pressure actuated means responsive to the pressure in
the fuel reservoir and connected to said first valve mechanism
whereby said first valve mechanism is operated to control the rate
of flow of fuel vapor and air from said inlet means to said outlet
means in accordance with the pressure of the fuel vapor in said
fuel reservoir, a second valve mechanism disposed between said fuel
vapor inlet means and said first valve mechanism and said pressure
actuated means for controlling flow of fuel vapor to said outlet
means as controlled by said first valve mechanism and to said
pressure actuated means, second spring means biasing said second
valve mechanism to shut off fuel vapor flow from said fuel vapor
inlet means and second differential pressure actuated means
responsive to the pressure in the induction system and operatively
connected to said second valve mechanism whereby said second valve
mechanism is operated to control the flow of fuel vapor from said
fuel vapor inlet means in accordance with the operating conditions
of the internal combustion engine.
7. A vapor regulating valve according to claim 6 wherein said
differential pressure actuated means is a diaphragm and wherein
said diaphragm and the baising force of said spring means are sized
so as to prevent opening of said first valve means below a
predetermined pressure of fuel vapor in said fuel reservoir.
8. A vapor regulating valve according to claim 6 wherein said
second differential pressure actuated means is a diaphragm and
wherein said diaphragm and the biasing force of said second spring
means are sized so as to keep said second valve mechanism closed to
prevent fuel vapor flow from said fuel vapor inlet means when said
internal combustion engine is off or running at low idle speed.
Description
This invention relates to a vapor regulating valve and, in
particular, to a vapor regulating valve for use in a system for
mixing air with fuel tank vapor to regulate and control the flow of
fuel vapor and air into the intake manifold of an internal
combustion engine as a function of engine operation.
It is well known that vapors and gases emitted from internal
combustion engines contribute to the present day problem of air
pollution. Accordingly, much attention has been directed to
controlling the polluting emissions from internal combustion
engines. Many corrective devices have been proposed and utilized to
control the most obvious source of emission, that is, the emission
of fumes from the exhaust system and crankcase of the engine.
Another source of hydrocarbon emission from an internal combustion
engine is the fuel vapor escaping from the fuel system. In
particular, gas vapor may escape from the external vents of both
the fuel tank and the carburetor float bowl, either while driving
or at rest. It has been estimated that of these uncontrolled fuel
evaporation losses, the loss from the fuel tank accounts for from
50 percent to approximately 75 percent of this total.
In an effort to reduce the fuel vapor emission from the fuel
system, various evaporative loss control device have been proposed
and utilized whereby the fuel vapors are contained and then
delivered to the intake manifold of the engine while it is in
operation for consumption therein. This approach has worked
successfully to help reduce the emission of fuel vapors directly
from the fuel system but, under certain engine operating
conditions, this feedback of the fuel vapors for consumption in the
engine has effected engine operation or has increased the exhaust
emission of unburned hydrocarbons, or both.
An improved system for mixing air with fuel tank vapors to overcome
the above-identified problem is disclosed in copending United
States Application Ser. No. 129,938 of Robert Seyfarth filed Mar.
31, 1971 and assigned to the same assignee as that of the subject
application. In this system, a mixing valve having a fuel vapor
pressure-controlled diaphragm-operated valve is used to meter fuel
vapor and air into the intake manifold of the engine during
operation of the engine.
It is therefore the principal object of this invention to improve a
vapor regulating valve for use in a system for mixing air with fuel
tank vapors whereby fuel tank vapor pressure applied against a
diaphragm raises a metering valve to control the flow of fuel vapor
and air to the intake manifold of an internal combustion engine,
with second diaphragm operated valve means being provided to
control the flow of fuel vapor as a function of engine
operation.
Another object of this invention is to improve a vapor regulating
valve for use in a system for mixing air with fuel tank vapors in
which a first valve means is used to control the flow of fuel tank
vapor to a second valve means which meters the flow of fuel vapor
mixed with air to the intake manifold of an internal combustion
engine.
A still further object of this invention is to improve a vapor
regulating valve for controlling the loss of fuel vapor from a unit
having a fuel reservoir and an internal combustion engine with an
induction system whereby the flow of fuel vapor from the fuel
reservoir to the engine is controlled as a function of engine
operating conditions and fuel vapor pressure.
These and other objects of the invention are attained by means of a
vapor regulating valve for mixing air with fuel tank vapor for an
internal combustion engine wherein the vapor regulating valve
includes a first diaphragm which controls the operation of a first
valve to control the flow of fuel vapor from a fuel tank to a
second or metering valve actuated by a fuel vapor actuated
diaphragm to meter the flow of a mixture of fuel vapor and air to
the engine for combustion therein.
For a better understanding of the invention, as well as other
objects and further features thereof, reference is had to the
following detailed description of the invention to be read in
connection with the accompanying drawings, wherein:
FIG. 1 is a schematic view of a portion of an engine fuel system
incorporating a system utilizing a vapor regulating valve of the
invention for mixing fuel tank vapors with air to the engine;
and,
FIG. 2 is an enlarged sectional view of the vapor regulating valve
of the system of FIG. 1.
Referring now to FIG. 1, an internal combustion engine 2 has an
induction system including a carburetor intake manifold 3 thereon
controlled by throttle valve 4, with an air cleaner 5 suitably
mounted on the carburetor intake manifold. A supply of fuel, such
as gasoline, for the engine 2 is contained in a fuel reservoir,
such as fuel tank 6, from which liquid fuel is delivered through a
suitable conduit and fuel pump, not shown, to the carburetor of the
engine. Fuel tank 6, provided with a filler neck 7 closed by a
non-vented cap 8, normally contains a quantity of liquid fuel with
the space above the liquid fuel containing fuel vapor. A conduit 11
is connected to the fuel tank in position to receive fuel vapor
from the tank and the conduit is provided with a vacuum relief
valve 12 and a pressure relief valve 14, both set to open at
predetermined pressures, as desired.
Fuel vapor from the fuel tank is delivered through the conduit 11
to the vapor regulating valve, generally designated 20, of the
invention in a manner to be described whereby the fuel vapor is
mixed with air and delivered by conduit 15 to the intake manifold 3
of the engine for combustion therein. Conduit 15 is connected to
the intake manifold below the throttle valve 4. The vapor
regulating valve 20 is connected in a suitable manner to a source
of clean air and is herein shown, for the purpose of illustration
only, as being connected by conduit 16 to the air cleaner 5. In
addition, in order to control the operation of the vapor regulating
valve 20 in relation to engine operating conditions, it is
connected by conduit 17 to the intake manifold 3, just above the
throttle valve 4 so that it is exposed to manifold vacuum when the
engine is operating off idle, for a purpose to be described.
Referring now to FIG. 2, the vapor regulating valve 20 includes a
valve housing 21 with top and side caps 22 and 23, respectively,
which together make up a casing divided into four chambers by
flexible diaphragms 24 and 25, each sealingly clamped at its outer
periphery between the housing and the caps 22 and 23, respectively.
The two chambers formed by the diaphragm 24 are a first or lower
chamber 26 and a second or upper chamber 27, while the two chambers
formed by diaphragm 25 are a third or vacuum left-side chamber 28
and a fourth or right-side chamber 29, as seen in FIG. 2.
The valve housing 21 is provided with a tube connection 31 for
connection to conduit 11 for the entry of fuel vapor into the valve
housing, the passage 31a in this tube connection being in
communication with a generally horizontally disposed annular
passage 32 which is concentric to a horizontally disposed passage
33 in the valve housing which is closed at one end, the left-hand
end as seen in FIG. 2, by a valve 34. This passage 33 is connected
by branch passage 33a to the lower chamber 26 and is closed at its
other end by a metering valve 35 seating on the annular valve seat
36 encircling the reduced end 33b of this passage.
The valve housing 21 is also provided with a tube connection 37 for
connection to the conduit 15 to supply a mixture of air and fuel
vapor to the intake manifold 3 of the engine 2. The passage 37a
through this tube connection terminates in an annular passage 38
defined between annular valve seat 36 and a second annular valve
seat 39 for the valve 35. A third tube connection 41 on the valve
housing 21 is adapted for connection to the conduit 16 for the
admission of clean air. The passage 41a through this tube
connection 41 is in communication with an annular passage 41b
which, when the valve 35 is unseated, is in communication with
passages 33 and 38 so that fuel vapor and air from these passages
are mixed and delivered to the engine 2 via conduit 15 to the
intake manifold 3.
The valve 34 made of suitable material, such as synthetic rubber,
is in effect a diaphragm type valve with a central enlarged valve
portion 34a and with a flexible annular portion 34b sealingly
clamped at its outer periphery between the valve housing and a
retaining ring 42 secured to the valve housing. The central portion
of the valve 34 is provided on one side thereof with a flat surface
portion to engage the valve seat 47 at the end of passage 33 and on
its opposite side this central portion abuts against one side of
diaphragm 25. The diaphragm 25 is normally biased so as to position
valve 34 against valve seat 47 to close off the left-hand end of
passage 33, as seen in FIG. 2, by means of a spring 43 abutting at
one end against a diaphragm plate 44 on one side of the diaphragm,
opposite valve 34, the left-hand side as seen in FIG. 2, and at its
other end against an inside surface of cap 23, the spring 43
encircling an annular boss 23a extending inwardly of the cap 23. As
previously described, the diaphragm 25 separates chamber 28 from
chamber 29 with the chamber 28 being in communication through port
45 in the cap 23 and via conduit 17 with the intake manifold 3 on
the upstream side of throttle valve 4. Chamber 29, which is
actually formed by diaphragm 25, valve housing 21 and a second
movable wall in the form of valve 34, is in communication with the
atmosphere via port 46 in valve housing 21.
Metering valve 35, also made of a suitable material, such as
synthetic rubber, is in effect a diaphragm type valve with a
central valve portion 35a and a flexible annular portion 35b with
portion 35b sealingly clamped at its outer periphery between the
valve housing 21 and a retainer ring 51. As is apparent, metering
valve 35 forms a second movable wall of the previously described
lower chamber 26. The central body portion 35a of this valve is
fixed to one end of a valve support 52 which is attached at its
opposite end to the diaphragm 24 by means of a pair of diaphragm
plates 53 positioned on opposite sides of the central portion of
the diaphragm 24. The diaphragm 24 and therefore the valve 35 are
normally biased downward, as seen in FIG. 2, to the valve closed
position by means of a spring 54 abutting at one end against the
uppermost diaphragm plate 53 and at its opposite end against the
inside surface of the cap 22, the spring 54 encircling an annular
boss 22a within the cap 22 and formed integral therewith. The
diaphragm 24 and cap 22 form the upper chamber 27 which is vented
to the atmosphere by means of port 55 in the cap 22.
In the vapor regulating valve described, the force of spring 43 and
the relative working areas of diaphragm 25 and of valve 34 are
chosen so that, for example, valve 34 is effective to seal fuel
vapor from fuel tank 6 up to a fuel vapor pressure of 6 pounds per
square inch, for example, while still permitting this unit to
function in a manner to be described, on a low level vacuum signal
of for example 2 inches of mercury. With this arrangement, valve 34
will thus remain closed when the engine is either off or running at
idle so that fuel vapor is not admitted to the intake manifold
during these periods of time. In a similar manner, the spring 54
and the effective working areas of diaphragm 24 and metering valve
35 can be chosen so that, for example, metering valve 35 is not
unseated until fuel vapor pressure is greater than 1/2 pounds per
square inch. It can also be seen that the effective working areas
on opposite sides of metering valve 35 must also be taken into
consideration, since when fuel vapor is admitted to passage 33 and
lower chamber 26, the pressure of this fuel vapor is applied on
opposite sides of this metering valve. By careful consideration of
the above factors and proper sizing of the reduced end 33b of
passage 33 and of annular passage 41b a proper fuel vapor and air
mixture can be obtained with the valve 35 operating as a metering
valve to control the flow of fuel vapor and air from these passages
to the annular passage 38, passage 37a and then via conduit 15 to
the engine 2.
The function of the vapor regulating valve under different modes of
engine operation, that is, engine-off, engine running at idle
position and engine off-idle, and at various fuel vapor pressures
is as follows:
With the engine off or with the engine running at low idle speed,
the positions of the valve 34 and of the metering valve 35 are as
shown in FIG. 2 with these valves seated against their respective
valve seats by the action of diaphragms 25 and 24, respectively, as
biased by springs 43 and 54, respectively. In this position, the
valve 34 blocks the flow of fuel vapor from the fuel tank 6 so that
there is a complete fuel vapor shut-off up to a predetermined
pressure as previously described. Pressure relief valve 14 on
conduit 11 is used to prevent over-pressuring, as desired, of the
fuel tank 6.
When the engine is running at an off-idle mode of operation, a
sufficient vacuum, for example, 2 inches of mercury, is produced in
the chamber 28 so that the higher atmospheric air pressure in
chamber 29 acting on the opposite side of the diaphragm 25 from
vacuum chamber 28 will overcome the biasing action of spring 43 to
effect movement of the diaphragm to the left, as seen in FIG. 2.
This movement of the diaphragm to the left now permits the fuel
vapor pressure in passage 32, even though this fuel vapor pressure
may be low, to effect movement of valve 34 to the left to unseat it
from the valve seat 47 at the end of passage 33 so as to establish
a flow path between passages 32 and 33. Fuel vapors can now enter
passage 33 and via passage 33a into the chamber 26 to operate
against one side of diaphragm 24. However, if the fuel vapor
pressure is, for example, under 1/2 pounds per square inch, no fuel
vapor will flow from the fuel tank 6 to the engine because this
fuel vapor pressure acting against diaphragm 24 is insufficient to
overcome the biasing action of spring 54 to permit unseating of the
valve 35 from the seats 36 and 39. At the same time, metering valve
35 will block the flow of air from conduit 16 through passages 41a
and 41b into passage 37a to the engine.
With the engine running off-idle with vapor pressures of greater
than, for example, 1/2 pounds per square inch in the fuel tank 6,
the vapor pressure will be sufficient to move diaphragm 24 upward,
as seen in FIG. 2, to unseat metering valve 35 from seats 36 and 39
to now allow air entering through passage 41 to mix with the fuel
vapors entering through passage 33 and permit this mixture of air
and fuel vapors to be discharged through passage 37a and via
conduit 15 to the intake manifold 3 of the engine. Fuel vapors will
thus flow to the engine until such time as the fuel vapor pressure
drops below a predetermined value, for example, below 1/2 pounds
per square inch, at which time the diaphragm 24 can again move
downward by the biasing action of spring 54, to the position shown
in FIG. 2, to effect seating of metering valve 35 against the valve
seats 36 and 39 to cut off further fuel vapor flow from the fuel
tank 6 via conduit 11 and air flow from conduit 16 to the engine or
until the engine is running at low idle or is at engine-off at
which time the vacuum in chamber 28 is reduced sufficiently to
allow spring 43 to bias diaphragm 25 against valve 34 to shut-off
flow of fuel vapor from passage 32 to passage 33.
* * * * *