Automatically opening canister purge solenoid valve

A canister purge valve comprising: a housing (12) including a vacuum chamber (14) communicated to an extending vacuum port (16) and an opening (26); an assembly (40) received within the housing (12) including a valve seat (76) positioned within the vacuum chamber (14) and an axially extending inlet port (58) extending through the opening (26) in said housing (12). The valve including a plurality of passages (57, 60, 62) communicating the inlet port (58) to the vacuum chamber (14); valve means (90, 92, 94, 96) movably positioned within the vacuum chamber (14) for seating upon the valve seat means for biasing (98) the valve means (90, 92, 94, 96) against the valve seat (76) and means for generating (42, 44, 52, 100, 120) a magnetic flux signal in response to control signals for urging the valve means to seat upon said valve seat (76).

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention generally relates to solenoid valves, and more 
particularly to an improved solenoid valve which varies the rate at which 
hydrocarbons can be removed from an evaporation canister and re-enter the 
intake manifold of an engine. 
To eliminate the flow of hydrocarbons into the atmosphere, internal 
combustion engines use an evaporation canister which stores hydrocarbon 
vapors from within the engine and the fuel tank. Upon restarting the 
engine, the free hydrocarbons within the evaporation canister are returned 
to the intake manifold. In order to prevent an excessive amount of 
hydrocarbons from appearing in the exhaust when the engine is started, the 
rate at which the hydrocarbons are permitted to flow from the canister 
into the intake manifold is controlled by an electrically operated 
canister purge valve. Such valve can be of a normally closed or normally 
open variety. Normally open valves found in the prior art which remain 
open when no power is applied thereto require the use of a check valve to 
prevent vapor from flowing into the atmosphere while the engine is not 
running. The normally closed solenoid valve obviates the need for a check 
valve since such valves remain closed until control signals are 
communicated to the solenoid. However, the failure of such normally closed 
valves will cause the emission control system to fail to meet evaporative 
emission requirements by not being able to open and close at proper times. 
It is an object of the present invention to eliminate those deficiencies 
found in the prior art. A further object of the present invention is to 
provide an automatically opening canister purge solenoid operated valve 
which is capable of a maximum flow of approximately 2.0 standard cubic 
feet per minute (56,634 cubic millimeters per minute) of air at a pressure 
differential of 10 inches (25.4 centimeters) of mercury. 
A further object of the present invention is to provide a canister purge 
valve which opens automatically under the influence of intake manifold 
pressure thereby ensuring that hydrocarbons within the evaporation 
canister can be combusted within the engine regardless of the operable 
condition of an electrically energized coil. 
A further object of the present invention is to provide a valve which is 
normally closed in the absence of any external influences. 
A further object of the present invention is to provide a valve in which 
the rate at which hydrocarbons are permitted to re-enter the intake 
manifold is variable and electrically controlled. 
Another object of the present invention is to provide a low cost, 
repeatably operating solenoid activated valve having an improved magnetic 
circuit. 
Many other objects, purposes, features and advantages of the invention will 
be clear from the detailed description of the drawings. 
Accordingly, the invention comprises a canister purge valve comprising a 
housing including a vacuum chamber communicated to an axially extending 
vacuum port and an opening; an assembly received within the housing 
including a valve seat positioned within the vacuum chamber. The assembly 
further including an axially extending outlet port extending through the 
opening in the housing and a plurality of passages communicating the 
outlet port to the vacuum chamber, the valve further including means for 
providing a seal between the housing and the assembly proximate the vacuum 
chamber, valve means movably positioned within the vacuum chamber for 
seating upon the valve seat for opening and closing communication between 
the inlet port and the outlet port, means for biasing the valve means 
against the valve seat, and means for generating a magnetic flux signal in 
response to control signals for urging the valve means to seat upon the 
valve seat.

DETAILED DESCRIPTION OF THE DRAWINGS 
With reference to the accompanying FIGURES, there is illustrated an 
automatically opening canister purge valve 10 which includes a housing 12 
that is preferably constructed of a non-magnetic, non-electric material 
such as plastic. The housing defines at its upper extreme as viewed in 
FIG. 1, a pressure chamber 14. The pressure chamber 14 is communicated to 
a source of vacuum such as the intake manifold of the engine through a 
vacuum port 16. The port is formed by a passage 17 within the housing 12. 
The passage includes an orifice such as the flat edge orifice 18. The 
housing 12 further includes an integrally molded electric connector 19 
housing a plurality of electrical terminals 20. The walls 22 of the 
housing forming the vacuum port 16 and vacuum chamber 14 are provided with 
an annular shoulder 24. The housing is further provided with an opening 
26, the purpose of which will be apparent from the description below. 
Fitted within the housing 12 is a coil and outlet port assembly generally 
designated as 40. The assembly 40 comprises a bobbin or carrier 42 The 
carrier 42 comprises an axially extending cylindrical wall or member 52 
defining a central stepped passage 54. An electromagnetic coil 44 is wound 
about the member 52. The ends of the coil 44 are connected by way of 
connectors 50 to the terminals 20. It should be noted that only one of the 
coil connectors 50 can be seen in FIG. 1. 
Integrally molded as part of the assembly 40 and axially extending from the 
carrier 42 is a member 56 having a passage 57 therein forming an outlet 
port 58. The inlet port 58 is adapted to be communicated in a known manner 
with the evaporative emissions collection canister of the vehicle. The 
lower end of the axially extending passage 57 intersects a radially 
extending passage 60 which terminates at an axially extending bore or 
passage 62 having a diameter preferably greater than the larger diameter 
portion of passage 54. The end of passage 60 opposite bore 62 is closed by 
plug or insert 66 which may be ultrasonically welded in place. 
The bore 62 is formed by an upraised boss generally designated as 70 which 
is formed as an integral extension of the assembly 40. The boss 70 
includes a circumferentially extending notch 72 which supports an O-ring 
74. The boss 70 extends into the vacuum chamber 14 and the O-ring 74 
provides for sealing against the housing 12. The boss 70 terminates at an 
annular flat valve seat 76 positioned about passage 62 within the vacuum 
chamber 14. Moveably positioned within the vacuum chamber 14 is a flat 
ferro-magnetic disk 90 supporting on its underside 92 a ring 94 of 
compliant material such as rubber for seating upon the valve seat 76 which 
when seated thereon closes communication between the vacuum port 16 and 
the input port 58. The disk 90 is preferably circular and includes a 
plurality of openings 96. The disk 90 is biased towards the valve seat 76 
by a spring 98. 
Positioned within the bore 54 is a ferro-magnetic metal stator 100. The 
stator 100 comprises a plurality of outwardly directed barbs 102 
preferably positioned thereon such when the stator 100 is positioned 
within the bore 54 its end 104 is slightly above the valve seat 76 with 
the barbs 102 engaging the upper narrow portion 55 of the member 52. This 
narrowing portion 55 of the stepped bore 54 permits the barbs 102, upon 
insertion therein, to deform the member 52 to hold the stator 100 in its 
desired orientation. The stator 100 further comprises an end 106 which 
extends from the lower portion 112 of the cylindrical member 52. 
Positioned in contacting engagement with the end 104 of the stator 100 is 
a ferro-magnetic strap generally designated as 120. The interaction of the 
metallic strap 120, assembly 40 and housing 12 is more clearly illustrated 
in FIG. 2. 
The strap 120 comprises a substantially flat piece of metal bent to form a 
U-shaped member having a bottom 122 and a plurality of sides 124a and 
124b. The sides 124a and 124b terminate at ends 126a and 126b which are 
received within narrow slots 128a and 128b fabricated within the housing 
12. The strap 120 may be secured to the housing 12 by providing the ends 
126a and 126b with outwardly extending barbs which deform the walls of the 
cooperating slots 128. The barbs are not visible in the drawings. Upon 
assembly of the various components of the valve 10 within the housing 12, 
a potting compound 130 may be inserted into the housing 12 to secure the 
assembly 40 and strap 120 permanently in place. An end cap 132 may be 
provided to enclose the open end 134 of the housing. 
During assembly of the valve 10, the assembly 40 is inserted within the 
open end 134 of the housing 12 and is fitted against the shoulder 24. The 
axially extending member 56 defining the inlet port 58 is received through 
the opening 26 in the housing 12. By incorporating the inlet port 58 as 
part of the assembly 40, rather than fabricating the inlet port 58 as part 
of the housing, as done in the prior art, eliminates the requirement to 
provide vacuum seals within the housing 12 proximate the passage 57 of the 
inlet port 58. 
The slots 128 within the housing 12 are positioned such that when the strap 
120 is in place against the stator 100, the ends 126 of the sides 124 
extend above, as viewed in FIG. 2, the disk 90. 
The coil 44, stator 100, strap 120 and disk 90 form the preferred magnetic 
circuit of the valve 10 through which metallic flux will flow upon 
activation of the coil 44 in response to controlled signals communicated 
thereto. By positioning the ends of the strap 126 above the disk 90 the 
magnetic flux is directed to flow through the disk 90 and stator 100 
thereby improving the repeatability of the operation of the valve 10. 
Many changes and modifications in the above-described embodiment of the 
invention can, of course, be carried out without departing from the scope 
thereof. Accordingly, that scope is intended to be limited only by the 
scope of the appended claims.