Fuel vapor managment valve

An electrically controlled vacuum operated fuel vapor canister purge valve having a regulator valve subassembly with a vacuum signal chamber on one side of a pressure responsive power diaphragm which moves a regulator valve obturator for controlling flow from a vapor inlet passage to a vapor outlet passage for connection to an engine inlet. The vacuum signal chamber has a vacuum signal connection port and a recess or well with an atmospheric vent port and resiliently deflectable locking tab. A solenoid operated atmospheric bleed valve has a boss with a restrictor outlet which is quick-connected and seated in the well for electrically controlling vent flow into the vacuum signal chamber. The restrictor limits atmospheric bleed flow to attenuate the effects of sudden changes in the vacuum signal.

CROSS-REFERENCE TO RELATED APPLICATIONS 
Not Applicable 
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
Not Applicable 
MICROFICHE APPENDIX 
Not Applicable 
BACKGROUND OF THE INVENTION 
The present invention relates to valves of the type employed for 
controlling purging of fuel vapor stored in a canister connected to 
receive vapors from a vehicle fuel tank and for introducing the vapor 
purge flow into the inlet of the vehicle engine. Such valves are known in 
the art and typically utilize a vacuum signal such as from the engine 
manifold, to control the pressure on one side of a power diaphragm 
employed to control the movement of a valving member or obturator with 
respect to a valve seat or port for controlling flow of the vapor between 
the canister and the engine inlet. In order to provide electrical control 
of the vapor purge flow to the engine inlet where the engine operation is 
controlled by electrically actuated fuel injectors an electrically 
operated valve is employed to control atmospheric bleed to a vacuum signal 
chamber on one side of the power diaphragm. 
However, vapor management valves of the aforesaid type employing a vacuum 
generated control signal for the power diaphragm are effected by changes 
in the engine manifold vacuum. When the engine throttle is closed, from an 
engine loaded condition, a strong manifold vacuum is applied through the 
regulator valve outlet to the underside of the power diaphragm. The 
restrictor in the vacuum signal port causes a lag in the corresponding 
vacuum level being created above the power diaphragm in the vacuum signal 
chamber; and, therefore the diaphragm is moved downwardly by the pressure 
differential to substantially decrease the vapor purge flow to the engine 
inlet. This condition is sometimes referred to as "tip-out" and can result 
in an overly lean fuel/air mixture and can cause engine stalling, 
particularly at engine idle. 
It has thus long been desired to provide a way or means of providing for 
improved control of fuel vapor canister purge in a vehicle engine emission 
control system and to provide such improved control a relatively low cost 
and an easy to manufacture valve and to provide for electrical control of 
the purge valve in a manner which can accommodate or compensate for 
changes in engine manifold vacuum as experienced when the throttle is 
closed during engine operation. 
BRIEF SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an easy to manufacture 
and relatively low cost electrically operated fluid pressure signal 
actuated vapor management valve for controlling flow of fuel vapor purge 
from a canister to an engine inlet. 
It is a further object of the present invention to provide an electrically 
operated fluid pressure actuated vapor management valve which is low in 
manufacturing costs and easy to assemble and which can accommodate 
numerous different flow conditions for different engine applications 
without requiring redesign or retooling of the valve assembly. 
It is a further object of the present invention to provide an electrically 
operated fluid pressure actuated fuel vapor management valve which can 
utilize a single electrically operated vent valve for numerous different 
flow requirements of various different engines without the need for 
significant modifications of the valve. 
It is a further object of the present invention to provide a solenoid 
operated vent valve for controlling atmospheric bleed flow to the vacuum 
signal pressure chamber of a vapor management valve for controlling the 
differential pressure across a power diaphragm for moving the fuel vapor 
purge valve and controlling flow from the canister to the engine inlet. 
The present invention provides a fuel vapor canister purge valve which 
employs a vacuum signal actuated diaphragm operated regulator valve for 
controlling flow from the canister to an engine inlet. The valve of the 
present invention has the regulator housing provided with a vent port in a 
recess or well which has a solenoid operated vent or atmospheric bleed 
valve (EVR) quick-connected therein. A restrictor is provided upstream of 
the vent port in the regulator housing and preferably in the outlet of the 
EVR for controlling flow to the vent port in the regulator housing and 
particularly to prevent or delay loss of vacuum in the signal pressure 
chamber. Alternatively the EVR may have the restrictor located at its 
inlet. The restrictor in the outlet of the solenoid operated vent valve or 
EVR may be easily changed during manufacture; and, the flow 
characteristics of the vent valve thereby changed to accommodate different 
engine applications. The design and structure of the regulator valve thus 
may be common to many different applications. 
The valve arrangement of the present invention enables use of a common 
regulator valve for mounting on engines with the different purge flow 
requirements to be accommodated by merely changing the outlet port size in 
the solenoid vent valve (EVR) which is preferably quick-connected to the 
regulator housing.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to FIG. 1, the valve assembly of the present invention is 
indicated generally at 10 and includes a regulator valve subassembly 
indicated generally at 12 and an electrically operated vent or atmospheric 
bleed valve indicated generally at 14. The regulator valve subassembly has 
an inlet 16 which is adapted for connection to a fuel vapor canister 18 
which receives fuel vapors from a fuel tank 20 as indicated in dashed 
line. The regulator valve subassembly outlet 22 is formed in a connector 
fitting 24 which is adapted for connection to the engine inlet manifold 26 
via a hose indicated by dashed line in FIG. 1. The regulator valve 
subassembly 12 includes a housing structure 28 defining therewithin a 
vacuum signal chamber 30 which has one wall thereof formed by a pressure 
responsive diaphragm 32. Housing structure 28 has a vacuum connector 34 
which is adapted for connection to the manifold 26 via a hose indicated by 
dashed line in FIG. 1. Connector 34 has restricting orifices 35, 37 
therein to provide reduced flow and prevent sonic choking. Diaphragm 32 
has an insert or backing plate 34 provided on the upper surface thereof; 
and, the vacuum plate has a portion thereof extending through the 
diaphragm which portion has provided thereon a resilient poppet 36 which 
is moveable with the diaphragm 32 with respect to a valve seat 38 formed 
in the housing and ported through a passage 40 to the outlet passage 22. 
The diaphragm forms a pressure regulator valving passage 42 underneath the 
diaphragm and in conjunction with the bottom wall 44 of the housing 28; 
and, if desired a baffle plate 46 having a plurality of surge preventing 
apertures 48 formed therein is disposed in a chamber 42. 
The diaphragm 32 and backing plate 34 are biased downwardly in a direction 
tending to urge poppet 36 against valve seat 38 by the lower end of a 
spring 50, the upper end of which is registered on a keeper or retainer 52 
which is registered against an adjustment screw 54 threadedly engaged in a 
bore 56 provided in the upper portion of the housing 28. 
The regulator housing 28 has a vent port 58 located in a recess or well 60 
formed in the upper portion of housing 28. Well 60 has formed therein at 
least one locking tab 62 as shown in FIG. 2 which has a shoulder or 
projection 64 provided thereon and which is locked over lug 76 on boss 70 
preferably rotatably or twist-locking. In order to form the locking tab 62 
it is necessary to provide a relief or cut-out 66 in the bottom of the 
recess or well 60 for mold pins or slides during molding of body 28. 
The cut-out 66 forms an additional vent port to the signal chamber 30 in 
addition to the vent port 58, thus, it is virtually impossible to provide 
accurate flow limitation in the venting of the chamber 30 to the 
atmosphere in the construction of the housing 28. 
The electrically preferably solenoid operated vent or bleed valve or EVR 14 
has a body 68 which has formed on the lower end thereof a boss 70 which 
has formed thereon an annular groove 72 into which is received an annular 
seal ring 74 for sealing between the boss 70 and recess 60. The boss 70 
has formed on one side thereof a projection or lug 76 which is operative, 
upon insertion of the boss 70 into recess 60 to be twist-locked on 
projection 64, thereby retaining the valve body 68 in position in the 
recess 60. 
The body 68 of EVR 14 has formed in the end of boss 70 a flow restricting 
orifice 78 which serves to restrict flow of atmospheric bleed air into the 
recess 60. Recess 60 is sealed by ring 72 and thus the orifice 78 
restricts all bleed flow through vent port 58 and cut-out 66 to the 
chamber 30. Flow restricting orifice 78 is shown in the embodiment of FIG. 
2 as formed in an insert 79, but may also be formed integrally as one 
piece with body 68 of EVR 14. 
EVR 14 has a coil bobbin 80 with a coil 82 of electrical conductive 
material, such as magnet wire, wound therearound; and, coil 82 is 
surrounded by a ferromagnetic flux carrier or pole frame 84. The bobbin 
has a tubular ferromagnetic pole piece 86 disposed centrally therein. A 
moveable armature 88 is disposed adjacent the lower end of the pole piece 
86 and registers against a non-magnetic stop member 90 having the form of 
a sleeve with an annular flange formed thereabout and disposed about the 
pole piece 86. Armature 88 preferably has notches or peripheral cut-outs 
94 for facilitating flow therearound. Coil 82 has the ends thereof 
connected to suitable electrical terminals, one of which is shown in FIG. 
2 and denoted by reference numeral 92 which extends outwardly into a 
receptacle 94 formed in the EVR body 68. 
Referring to FIG. 1, pole piece 86 has the bore 87 thereof communicating 
with a chamber 96 which is covered by a filter 98 which communicates with 
a plenum 100 formed under cap 102. Plenum 100 communicates, through a 
clearance formed around the inner periphery of cap 102 with the atmosphere 
as indicated in FIG. 1 by the black arrow. 
Referring to FIG. 2, armature plate is biased upwardly toward sleeve flange 
91 by a spring 22. 
In operation, with a vacuum drawn in chamber 30, and the recess 96 of boss 
70, the pressure differential on armature plate 88 effects a net downward 
force on the armature plate overcoming the bias of the spring 104 and 
effects opening of the bore 87 to permit atmospheric flow from plenum 100 
and chamber 96 to restrictor passage 78. 
Energization of the coil 82 imposes an electromagnetic force in an upward 
direction on the armature plate 88 and changes the upward bias force 
comprising the sum of the electromagnetic force and the spring bias on the 
armature 88. The downward force on armature 88 comprises the differential 
pressure of the atmosphere above the armature and the vacuum in chamber 96 
acting over the area of armature 88 within the diameter of flange 91. It 
will be understood that the net force, i.e., the vector sum of the upward 
and downward forces determines the movement of the armature with respect 
to flange 91; and, thus the flow through orifice 78 and the vacuum in the 
recess 96 and chamber 30, which acts on the diaphragm 32. 
Referring to FIG. 4, a family of flow curves are presented for various 
sizes of the flow restricting orifice 78 as a function of engine manifold 
vacuum for two different levels of duty cycle for the electrical signal to 
coil 82. The upper family of curves in FIG. 4 represents a 40% duty cycle 
or "ON" time for the coil; whereas, the low family of curves represents a 
35% duty cycle for the current in coil 82. In both sets of curves in FIG. 
4, it will be noted from the legend that the restriction imposed by 
orifice 78 produces a flattening or less roll-off of the flow curve, with 
increasing engine manifold vacuum, as compared with the lowest curve 
representative of prior art devices. 
Referring to FIG. 3, an alternative embodiment of the invention is 
illustrated generally at 110 wherein pole piece 86' received in bobbin 80' 
of coil 82' has a restrictor orifice 112 formed in the upper end of bore 
87' in pole piece 86'. In the embodiment 110 of FIG. 3 it will be 
understood that the orifice in the end of the boss 70 is thus enlarged to 
have a diameter greater than the restricting orifice 112. 
The present invention thus provides a quick-connect EVR for a vacuum 
operated fuel vapor purge regulator valve whereby the EVR has a restrictor 
orifice in the flow outlet to prevent sudden changes in the vacuum signal 
for the power diaphragm in the regulator valve. Simple changes in the EVR 
restrictor orifice can accommodate different engine requirements, without 
retooling the regulator valve. 
Although the invention has hereinabove been described with respect to the 
illustrated embodiments, it will be understood that the invention is 
capable of modification and variation and is limited only by the following 
claims.