Note: Descriptions are shown in the official language in which they were submitted.
~ 1 --
BACKGROUND OF THE INVENTION
The present invention relates to electrically
operated valves for use in providing a fluid pressure
control signal. In particular, the invention relates to
5 electromagnetically actuated valves for providing a
variable vacuum signal for use in controlling a fluid
pressure servoactuator in response to an electrical
control signal.
In automotive engine and accessory control
10 systems, it has been found particularly convenient to
employ engine developed vacuum as a source of fluid
pressure for operating vacuum servoactuators or motors
for various engine control functions. Bowever, as
automotive engines have decreased in displacement in the
15 interests of reducing weight and fuel consumption, the
amount of vacuum available for accessories has
substantially diminished.
Heretofore, on-board vacuum control systems
have employed electrically operated control valves
20 which, during periods of control operation, provided for
valve actuation between a vacuum supply port and an
atmospheric venting orifice in a manner analogous to a
single-pole double-throw switch. In such arrangements,
an electrical coil moved an armature-valve member
25 between one position opening a vent port and closing a
vacuum port and another position closing the vent port
and opening the vacuum port~ This known valving
arrangement thus resulted in a continuous flow of
atmospheric air or vent bleed into the engine valving
30 chamber and thus to the vacuum source.
~`
It has also known to employ dual electrical
coils for individually actuating a vacuum and vent valve
poppet member in response to electrical control
signals. Such dual coil valve arrangements have
5 necessarily resulted in bulkiness of the control valve
and increased manufacturing costs in providing two
electrical coils and the associated electrical
connections thereto.
The aforementioned dual coil vacuum control
10 valve, also provides continuous flow of atmospheric air
to the valving chamber which reduces the engine manifold
vacuum and drains engine power.
Thus, it has long been desired to find a way or
means of providing a vacuum control signal in response
15to an electrical input control signal and provide such a
function without causing continuous bleed of atmospheric
air into the vacuum source.
Furthermore, it has been desired to provide
such a control valve which is electrically operated by a
20 single coil and yet provides a control signal by
alternately applying vacuum and venting a control signal
pressure chamber without permitting continuous bleed of
atmospheric air to the vacuum source.
It is known in the solenoid art to utilize a
25 permanently magnetized armature in association with the
magnetic forces generated by current flow in an
electrical coil. Examples of such devices are described
and shown in the periodical "Design", Volume , No.
1981 at page 42 published by Penton Publishing Company,
30Cleveland, Ohio. The use of a permanent magnet armature
for an electromagnetically actuated device permits short
current pulses to latch the armature. Movement of the
armature in an opposite direction for latching is accom-
plished by short current pulses of opposite polarity.
Thus it has been desi.red to find a way of usiny
electromagnetic actuation to actuate and holda con-trol valve
for providing a vacuurn control signal in response to an
electrical signal applied -to a single coil and yet provide
such control signal without permitting continuous vent flow
through the valve to the engine vacuum source.
According to one aspect of the pxesen-t invention
there is provided an electromechanical fluid pressure signal
control valve which has a housing means defining there within,
a fluid valving chamber having a fluid flow inlet port, an
outlet port and a fluid signal port communicating therewith,
the housing means including means defining a valve seat about
each of the inlet and outlet ports. Electrical coil means
is provided which has a s-tationary ferromagnetic core, and
an inlet poppet means is disposed for movement with respect
to the inlet valve seat while an outlet poppet means is
disposed adjacent the outlet valve seat, the inlet and outlet
poppet means each including a permanent maynet polarized
in the direction of poppet movement with the inlet poppet
means being disposed adjacen-t one axial end of the coil means
and the outlet poppet means being disposed adjacent the
opposite end of the coil means. Means biases the poppet
means toward their respective valve seats, so that upon
electrical current of a given polarity flowing in the coil
means, the axial ends of the core are magne-tically oppositely
polarized and one of the inlet or oulet poppets is seated
against the respective adjacent valve seat by the summed
forces of the bias plus the magnetomotive repulsion force
generated by the current flow, and the other of the poppet
means is moved away from the respective adjacent valve seat
by the magnetomotive attraction force overcoming the force
of the biasing means and is magnetically latched to the core
so as the current flows and upon cessation of the current
flow the moved poppet means is unlatched and reseated against
the valve seat by the biasi.ng means. Electrical lead means
is received through -the wall of the chamber and is adapted
for connec-tion of the coil to an external source of electrical
power.
- - 3 -
mab/ ,~'~
The present invention is a vacuum signal control
valve oE a type which may be used in automotive engine ~ccessory
control systems where an on-board source of vacuum is applied
to a vacuum servoactuator for effecting movement of a control
member. The control valve is electrically operated and
adapted to be controlled from a low current signal as, for
example, a series of current pulses made available from low
voltage solid state switchiny circuitry.
The present invention thus provides a solution to
the,above-described problem by employing a single electrical
~oil having a stationary iron core which upon energization
of the coil by current pulses of a given polarity creates
opposite magnetic poles at the ends of the core~ ~ndividual
moveable permanently magnetized armatures are disposed adjacent
'o koth ends of t~e coil core and one arn:ature i,s repelled
while the other attracted. The permanent magnet armature
which is attracted is latched to the core end by pulsing the
coil with a given polarity. Reversing the current pulse-
polarity reverses the order of repulsion and attraction for
the permanently magnetized armatures.
- 3a -
mab/~, ~ ~'
'7'~
4 --
The armatures are both spring biased in a direction away
from the coil core and toward, respectively, a vacuum
vent and vacuum supply port seat. When the coil is
deenergized both armature-poppets are seated thereby
5 closing the ports to the valving chamber and no bleed
flow is permitted to the vacuum source.
The present invention thus provides a novel
electrically energized control valve employing a single
coil which, upon electrical energization of the coil by
10 current pulses of desired polarity, provides a varying
fluid pressure control signal in a valving chamber. The
invention is described with respect to the particular
negative fluid pressure, or vacuum application. When
the coil is not energized both the vacuum supply and
15 vent ports to the valving chamber are closed and thus
the valve prevents atmospheric bleed through to the
vacuum source when a period of dwell is encountered and
no variation is required in the vacuum control signal.
The valve of the present invention requires no
20 holding current in the coil during periods of dwell and
thus is energizable by a low power electrical control
signal. The present valve thus provides a unique and
novel solution to the problem of providing a low cost
single coil electrically actuated vacuum control valve
25 capable of being operated by low voltage current pulses
from solid state circui~ry and which does not cause
continuous vent-bleed of atmospheric air to the vacuum
source.
BRIEF DESCKIPTION OF THE DRAWINGS
FIGURE 1 is a cross-sectional view taken along
the electrical coil axis of the control valve of the
present invention; and,
-- 5 --
FIGURE 2 is a view similar to FIGURE 1 with a
portion of the section view rotated and illustrates an
alternate embodiment of the valve.
DETAILED DESCRI PTION
Referring now to FIGURE 1I the valve assembly
of the present invention is indicated generally at 10 as
having housing means formed of a main portion 12 having
a generally cylindrical configuration with a valving
cavity 14 formed therein. An atmospheric vent passage
0 16 i5 formed in one end thereof the housing and
intersects the wall of cavity 14 in the form of an
annular vent valve seat 18. Passage 16 communicates
with the atmosphere via a suitable dust filter 20
retained in the right-hand end of the housing portion 12.
The valving chamber 14 is closed on the
left-hand end by a cap portion 22 of the housing means
which is received in the main portion 12 and sealed
about the parting line 24 by any suitable expedient as,
for example, weldment. Cap portion 22 has an outwardly
20 extending vacuum connector portion 25 formed thereon
which is adapted for connection to a vacuum source
hose. Connector 25 has a vacuum inlet passage 26
extending therethrough which intersects the wall of the
chamber 14 in an annular vacuum valve seat 28. In the
25 presently preferred practice of invention, the annular
valve seats 18, 28 are axially aligned and disposed at
opposite ends of the valving chamber.
The wall of the main housing portion 12 has
extending therefrom, intermediate the ends thereof, a
30 connector 30 which is adapted for connection to an
output control signal hose. The connector 30 has an
output control signal passage 32 provided therethrough
which is ported to the valving chamber 14.
77
-- 6
An electrical coil 34 is received in the
valving chamber 14 and is wound on a bobbin having
flange 36 provided on one thereof for registering
against a shouldered surface 38 provided in the wall of
5 the valving chamber 14.
The coil 34 has a core 40 formed of
ferromagnetic material, or ma~erial of high magnetic
permeability, received therein with the ends 42, 44
thereof extending preferably beyond the ends of the coil
10 34.
A vacuum source valve poppet 46 is received in
the valving chamber and disposed for movement between
the vacuum source valve seat 28 and the end 42 of the
coil core. Similarly, a vent valve poppet 48 is
15 received in the valving chamber 14 and disposed
intermediate the vent valve seat 18 and coil core end 44.
In the embodiment of FIGURE 1, a compression
spring 50 biases the vacuum valve poppet 46 leftward
into contact with the vacuum valve seat 28. A
20 corresponding compression spring 52 biases the vent
valve poppet 48 rightward into contact with the vent
valve seat 18.
The valve poppets 46, 48 comprise permanent
magnets axially polarized in the direction of poppet
25 movement. The poppets 46, 48 are disposed with like
poles adjacent the ends 42, 44 of the coil core and as
hereinafter described function as moveable armatures
upon electrical energization of the coil.
A pair of suitable electrical leads 54, 56 pass
30 through the wall of the housing portion 12 and are
sealed by a ~uitable grommet 58 thus providing means for
external electrical connection to ~he coil.
7'~t
-- 7 --
In operation, a serie~ of current pulses, of
predetermined polarity, are applied to the coil leads
54, S6 and the resultant current flow in coil 34 creates
magnetic poles of opposite polarity in the ends 42, 44
5 of the coil core. The polarity of the current is chosen
such that the respective adjacent end 42 or 44 of the
coil core is of like polarity with the desired one of
the poppets 46, 48 which is thus repelled by the
magnetomotive force developed. The magnetomotive Eorce
lOsums with the bias of the spring to maintain the poppet
closed against the respective adjacent valve seat.
For a given current polarity, the opposite one
of the ends 42, 44 of the coil core has an opposite
polarity with respect to the permanent magnet poppet
15adjacent thereto. The adjacent poppet of opposite
polarity is attracted to the core end by the sum of the
forces of the permanently magneti2ed poppet and the
magnetic force of attraction generated in the core end
by current flow and the resultant magnetomotive force is
20sufficient to overcome the bias of ~he spring and move
the poppet away from its respective adjacent valve
seat. Upon the poppet contacting the core end, the
poppet is magnetically latched against the end of the
core. Upon cessation of the current flow in the coil,
25the force of magnetic attraction of the permanent magnet
alone is insufficient to overcome the force bias of the
spring for maintaining the poppet magnetically latched
against the core and the open poppet is returned to
contact its valve seat.
il3'77
If a series of current pulses of reverse
polarity is applied to the coil, the polarity of the
chosen one of the coil core ends 42, 44 will be
reversed. Thus, the reversing the port opening of the
5 valve. It will be understood that either valve poppet
may be opened by the application of electrical current
pulses of the appropriate polarity to the valve coil.
The choice of which poppet is to be opened is thus
determined by the choice polarity of the coil current.
It will be seem, however, that irrespective of
the polarity of the coil current for a given polarity,
only one poppet is moved away from its seat when current
flows in the coil; and, the other poppet is maintained
in the closed position.
The resultant "EITHER-OR" operation of the
valve poppets of the present invention prevents flow of
atmospheric bleed air through the valving chamber to the
vacuum source when the control signal is operable to
vary the pressure in the chamber 14 for varying the
20 output control signal.
It will be understood that by varying the width
of the pulses, the open time of the individual poppets
may be varied for controlling the rate of vacuum
increase or decay within the valving chamber to thus
25 give the valve the vacuum control signal response at the
desired rate.
Referring now to FIGURE 2, an alterna~e
embodiment of the invention, indicated generzlly at 60,
has a coil bobbin 62 preferably formed of plastic having
30 end flanges 64, Ç6 with a ferromagnetic core 68 received
therein and retained by end pole plates 70, 72 having
~%~3~7
portions thereof threadedly engaging the core 68 for
retaining the core in the center of the bobbin. The
assembly of the bobbin 62, core 68 and pole plates 70,
72 has sufficient clearance therethrough as for example
5 by core passage 71 to permit passage of air from noe end
of ~he bobbin to another.
An end cap 74 is received over the left end of
the bobbin flange 64 and has right-hand axial face of
the rim thereof sealed against the axial face of the
lObobbin flange periphery by a suitable gasket 76 such
that the end cap 74 defines a valving cavity 78 between
the cap and the bobbin flange. The cavity 78
communicates via the air passage 71 through the bobbin
with a corresponding valving cavity 80 formed about the
15righthand end face of the bobbin flange 66 by cap 82
having the axial face of the periphery thereof sealed
against the bobbin flange 66 by a suitable gasket 84.
End cap 74 has a fluid pressure passage B6
provided therethrough which ports into cavity 78 in the
20 form of an annular valve seat 88. Passage 86 is formed
in a portion of cap 78 comprising a connector portion 90
adapted for connection to a vacuum hose.
Similarly, cap 82 has a connector portion 92
extending rightwardly therefrom and having a passage 94
25 formed through connector 92 which is adapted for
connection to a vacuum hose. The passage 94 ports into
the valving chamber 80 by an annular valve seat 96
formed on the inside surface of the cap 82. Cap 82 also
has the signal output connector 96 formed thereon having
30 a passage 98 formed therethrough which por~s into
valving chamber 80.
-- 10 --
A movable armature 100 is received in valving
cavity 78 and has attached thereto a valve member in a
form of resilient pad 102, preferably formed of
elastomeric material, for contacting valve seat 8~. The
5 armature 100 is biased in a leftward direction in FIGURE
2 by a suitable flat spring 104 disposed between the
armature and the core pole 70O Spring 104 has guide
portions 106 provided thereon for maintaining the
armature centered about the valve seat 88.
Similarly, an armature 108 is disposed in
valving chamber 80 and has attached to the righthand
face thereof a valve member 110, preferably formed of an
elastomeric material, for sealing against valve seat
96. A suitable flat spring 112 biases the armature 108
15 rightwardly for effecting contact of valve member 110
with valve seat 96. In the presently preferred
practice, flat spring 112 has integral guide portions
114 provided thereon for centering armature 108 about
valve seat 96.
The armatures 100, 108 each comprise a separate
permanent magnet polarized axially with respect to core
68 and having like poles disposed adjacent the
respective core poles 70, 72.
A coil 116 of suitable electrical conductor is
25 wound about bobbin 62 and has leads 118, 120 extending
through an aperture provided in the wall of an extended
portion of end cap 82 for external electrical
energization of coil 116.
In the embodiment of FIGURE 2, a pole frame or
30 shell 118 formed of ferromagnetic material is disposed
about the coil and has the ends thereof terminating
adjacent the periphery of the armatures 100, 108 for
completing a magnetic loop between the armatures for
increasin~ the magnetic flux and hence the magnetomotive
force. In the presently preferred practice, the
embodiment of FIGURE 2 has the end caps 74, 82 retained
respectively against gaskets 76, 84 by end flanges 120,
5 122 provided on pole frame 11~.
It will be understood that the operation of the
embodimen~ of FIGURE 2, is otherwise the same as that
described above with respect to the embodiment of FIGURE
1 and further description ~hereof has been omitted
lOherein for the sake of brevity.
The present invention thus provides a unique
electrically operated vacuum control valve for providing
a variable fluid pressure, and particularly a vacuum,
control signal in response to a modulated electrical
15 control signal. The valve of the presen~ invention
employs a single electrical coil responsive to ~ series
of current pulses of a given polarity for al~ernately
opening either a vacuum or vent valve poppet, depending
on current polarity, while maintaining the other poppet
20 in the closed position to prevent atmospheric vent bleed
through the valving chamber to the vacuum source. The
valve of the present invention thus provides a no-flow
single coil electrically operated fluid pressure control
signal valve for application in systems requiring a
25 varying fluid pressure control signal for servoactuator
operation.
It will be understood by those skilled in the
art that the invention has been hereinabove described in
~he presently preferred practice as a vacuum valve and
30 that modifications and variations of the invention may
be made as for example positive fluid pressure valving,
and the inven~ion is limited only by the followin~
claims.
