U.S. patent application number 09/843341 was filed with the patent office on 2002-02-21 for proportional variable force solenoid control valve with armature damping.
This patent application is currently assigned to Saturn Electronics & Engineering, Inc.. Invention is credited to Cruden, John A. JR., Najmolhoda, Hamid, Nezwek, David A., Seid, David L..
Application Number | 20020020442 09/843341 |
Document ID | / |
Family ID | 25525915 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020020442 |
Kind Code |
A1 |
Najmolhoda, Hamid ; et
al. |
February 21, 2002 |
Proportional variable force solenoid control valve with armature
damping
Abstract
Proportional variable force solenoid valve for controlling the
pressure of a fluid in a fluid control system comprises a solenoid
housing having therein a solenoid coil, an armature movable in
response to electrical current applied to the solenoid coil, and a
biasing spring for biasing the armature in a direction to establish
a valve fluid pressure response to solenoid coil current. An inner
armature end cooperates with or engages a damping member residing
in a fluid damping chamber to reduce non-linear valve responses
resulting from pressure oscillations in the fluid control
system.
Inventors: |
Najmolhoda, Hamid; (Grand
Rapids, MI) ; Seid, David L.; (North Muskegon,
MI) ; Nezwek, David A.; (Marne, MI) ; Cruden,
John A. JR.; (Cedar Springs, MI) |
Correspondence
Address: |
Edward J. Timmer
Walnut Woods Centre
5955 W. Main Street
Kalamazoo
MI
49009
US
|
Assignee: |
Saturn Electronics &
Engineering, Inc.
|
Family ID: |
25525915 |
Appl. No.: |
09/843341 |
Filed: |
April 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09843341 |
Apr 25, 2001 |
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09430987 |
Nov 1, 1999 |
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6223761 |
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Current U.S.
Class: |
137/82 |
Current CPC
Class: |
G05D 16/2024 20190101;
Y10T 137/8659 20150401; Y10T 137/0396 20150401; Y10T 137/2278
20150401; G05D 16/2097 20190101; Y10T 137/86614 20150401 |
Class at
Publication: |
137/82 |
International
Class: |
F15B 005/00 |
Claims
We claim
1. A proportional variable force solenoid valve for controlling the
pressure of a fluid in a fluid control system, comprising a housing
having therein a solenoid coil, an armature movable in response to
electrical current applied to the solenoid coil, means for biasing
the armature in a direction to establish a valve fluid pressure
response to solenoid coil current, and a damping member cooperating
with the armature so as to move therewith, said damping member
being received in a fluid damping chamber in the housing to reduce
non-linear valve responses resulting from pressure oscillations in
the fluid control system.
2. The valve of claim 1 wherein the damping member is connected to
an inner end of the armature.
3. The valve of claim 1 wherein the damping member is separate from
and engaged by an inner end of the armature.
4. The valve of claim 2 or 3 wherein the damping member has a
cup-shaped cavity in the inner end thereof.
5. The valve of claim 1 wherein the damping chamber is defined in a
nozzle housing in which a fluid control valve resides.
6. The valve of claim 1 wherein the damping chamber is disposed
proximate a fluid exhaust port.
7. The valve of claim 1 wherein the armature disk is made of a
magnetically permeable material to carry magnetic flux into the
armature.
8. The valve of claim 6 wherein the armature disk is made of
steel.
9. The valve of claim 1 wherein the cross-sectional area of the
damping member and clearance between a periphery of the damping
member and a cooperating wall of the damping chamber are selected
to reduce pressure oscillations resulting from electrical,
mechanical and/or hydraulic noise in the controlled fluid system or
circuit, thereby improving valve response stability.
10. The valve of claim 1 having a damping area between the
periphery of the damping member and wall of the damping chamber in
the range of 0.0003 to 0.0004 inch.sup.2.
11. In a method of controlling the pressure of a fluid in a fluid
control system using a proportional variable force solenoid valve
in response to electrical current applied to a solenoid coil of a
proportional variable force solenoid valve to move an armature, the
improvement comprising moving a damping member with an inner end of
said armature in a cooperating fluid damping chamber in a manner to
reduce non-linear valve responses resulting from pressure
oscillations in the fluid control system.
12. The method of claim 11 wherein the damping member moves with
the armature by virtue of being fixedly connected to said inner end
of said armature.
13. The method of claim 11 wherein the damping member is separate
from said armature and contacted by said inner end of said armature
so as to move therewith.
14. A proportional variable force solenoid valve for controlling
the pressure of a fluid in a fluid control system, comprising a
housing having therein a solenoid coil, an armature movable in
response to electrical current applied to the solenoid coil, means
for biasing the armature in a direction to establish a valve fluid
pressure response to solenoid coil current, and a cylindrical
damping member cooperating with the armature so as to move
therewith, said damping member being received in a cylindrical
fluid damping chamber in the housing with a cross-sectional area of
said damping member and clearance between said damping member and a
cooperating wall of said damping chamber selected effective to
reduce non-linear valve responses resulting from pressure
oscillations in the fluid control system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a proportional variable
force solenoid operated valve that controls fluid pressure in
response to electrical current applied to a valve solenoid and,
more particularly, to a proportional variable force solenoid
operated valve having armature damping means to improve valve
response stability to pressure oscillations in the controlled fluid
system.
BACKGROUND OF THE INVENTION
[0002] A proportional variable force solenoid control valve that is
relative low in cost to manufacture and compact in size while
maintaining substantially linear proportional fluid control is
described in the Najmolhoda U.S. Pat. No. 4,988,074 issued Jan. 29,
1991, of common assignee herewith. The patented proportional
variable force solenoid control valve comprises an outer steel
solenoid housing and an aluminum valve member housing joined
together mechanically such as by tabs on the steel solenoid housing
being crimped about regions of the aluminum valve member
housing.
[0003] The proportional variable force control valve includes a
ferromagnetic (e.g. steel) armature suspended by low spring rate
springs at opposite ends of the armature within the bore hole of a
coreless solenoid bobbin for reciprocable movement between
positions corresponding to a closed valve position and fully open
valve position in response to applied electrical current to an
electromagetic coil. The position of the armature is controlled by
balancing the variable force of an electromagnetic field of an
electromagnetic coil and the force of the magnetic field of a
permanent ring magnet against the force of a compression coil
spring which biases the valve toward the closed position of the
valve. The electromagnetic coil, bobbin and armature reside in the
steel solenoid housing in a manner that the steel housing provides
a concentration of flux of the electromagnetic field at the
armature. The fluid control valve on the end of the armature moves
relative to a valve seat disposed in the aluminum valve housing to
communicate a fluid inlet to fluid exhaust ports so as to regulate
fluid pressure at fluid control ports in a manner proportional to
the magnitude of applied electrical current.
[0004] A commercially manufactured version of the aforementioned
patented proportional variable force solenoid fluid control valve
has been modified to include a stainless steel ball valve and a
separate stainless steel valve seat insert pressed in the nozzle.
The ball valve is captured in a stainless steel cage between the
valve seat and a rod-like, cylindrical shaped steel armature that
moves relative to the valve seat in a manner proportional to the
magnitude of electrical current applied to the electromagnetic
coil. As the armature moves relative to the valve seat to actuate
the valve, the ball valve is caused to follow the end of the
armature by virtue of fluid pressure in the valve member housing
and confinement in the ball valve cage in the bobbin. The fluid
inlet is communicated to fluid exhaust ports by opening of the ball
valve so as to regulate fluid pressure at fluid control ports in a
manner proportional to the magnitude of electrical current applied
to the coil.
[0005] A spool valve is disposed in the valve member housing for
providing a two stage, high flow capability wherein pressurized
fluid supplied to the inlet port initially is directed to bypass
the control ports and flows to an end of the spool valve to move it
from a zero fluid flow spool position to a maximum fluid flow spool
position relative to the control ports as determined by the
cracking pressure preset for the ball valve by adjustment of the
coil spring force. Thereafter, a second stage of operation involves
controlling the fluid flow through the control ports by moving the
spool valve between minimum and maximum flow spool positions in a
manner proportional to the magnitude of electrical current to the
coil. Such proportional variable force solenoid control valves
commercially manufactured to-date are operably mounted to a cast
aluminum transmission body or case by a clamp plate, bolt, or both
engaging an outer nozzle groove. The Najmolhoda U.S. Pat. No.
5,611,370 issued Mar. 18, 1997, also describes a proportional
variable force solenoid control valve that includes a substantially
non-magnetic common housing for the solenoid and control valve,
simplifying valve manufacture and construction while maintaining
substantially linear proportional fluid pressure control.
[0006] In use of the proportional variable force solenoid pressure
control valve in an electronically controlled automatic
transmission of an automobile or other complex hydraulic control
system, there are many sources of hydraulic and/or
electromechanical "noise" in the controlled fluid system, which can
initiate or aggravate system instability by causing a sympathetic
harmonic vibration in related system components. System hydraulic
vibrational instabilities can create detrimental valve performance
characteristics which affect vehicle performance or reliability. In
an automatic transmission, the proportional variable force solenoid
pressure control valve usually controls many critical system
parameters and its performance should be consistent and stable.
When a pressure control solenoid responds to the inherent
electronic and/or hydraulic system noise by being forced into an
uncontrolled vibration response, the entire fluid system may become
unstable.
[0007] An object of the present invention is to provide a
proportional variable force solenoid fluid control valve and method
having improved valve response stability to noise in the controlled
fluid system, especially in use in an electronically controlled
hydraulic automatic transmission application.
[0008] Another object of the present invention is to provide a
proportional variable force solenoid control valve and method
having improved valve response stability to noise in the controlled
fluid system by virtue of armature damping means.
SUMMARY OF THE INVENTION
[0009] The present invention provides a proportional variable force
solenoid fluid control valve and method for controlling the
pressure of a pressurized fluid in a fluid control system in
proportion to the current level of an electrical input signal. In
one embodiment of the present invention, the proportional variable
force solenoid fluid control valve comprises an armature in
engagement with a fluid pressure control valve and movable in
response to electrical current applied to a solenoid disposed on a
coil bobbin in a solenoid housing and means for biasing the
armature in a direction to establish a valve fluid pressure
response to current level supplied to the solenoid (i.e. fluid
pressure versus solenoid current).
[0010] In accordance with an embodiment of the present invention,
the armature includes or cooperates with a damping member, such as
an armature damping disk connected to or engaged by an inner end of
the armature, for movement therewith in a fluid damping chamber
disposed proximate the inner armature end to receive the damping
member in a manner to reduce or dampen pressure oscillations
resulting from electrical, mechanical and/or hydraulic noise in the
controlled fluid system or circuit, thereby improving valve
response stability. The cross-sectional area of the damping member
and clearance between the periphery of the damping member and the
cooperating wall of the damping chamber are selected to this end.
The damping member may be formed integral with the armature or
connected thereto, such as by press-fit. Alternately, the damping
member may be separate from the armature yet engaged thereby in a
manner to reduce or dampen pressure oscillations.
[0011] In one embodiment of the invention, the damping chamber is
disposed in a valve or nozzle housing proximate fluid exhaust
ports, although the invention is not limited in this regard.
[0012] The damping member may be made of a magnetically permeable
material, such as steel, to provide an improved magnetic flux
carrier to direct magnetic flux directly into the armature, while
reducing size of the solenoid unit, although the invention is not
limited in this regard.
[0013] The foregoing and other objects, features, and advantages of
the invention will become apparent from the following more detailed
description taken with the accompanying following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1-3 are longitudinal cross section views of different
embodiments of a proportional variable force solenoid fluid control
valve in accordance with embodiments of the present invention.
DESCRIPTION OF THE INVENTION
[0015] Referring to FIG. 1, a proportional variable force solenoid
fluid control valve 10 includes valve member 12 and associated
valve components disposed in a valve or nozzle housing 19a and a
solenoid 14 disposed in a generally cylindrical solenoid housing
19b in a manner to provide a fluid control valve of the general
type described in the Najmolhoda U.S. Pat. No. 4,988,074 of common
assignee herewith, the teachings of which are incorporated herein
by reference. The valve housing 19a can be made of aluminum, while
the solenoid housing 19b can comprise steel or other ferromagnetic
material pursuant to U.S. Pat. No. 4,988,074. The valve housing 19a
and solenoid housing 19b can be joined together by tabs (not shown)
of the solenoid housing 19b crimped over an annular shoulder of the
valve housing 19a as shown in U.S. Pat. No. 4,988,074, or formed as
a single, common housing, pursuant to Najmolhoda U.S. Pat. No.
5,611,370 with the common housing made of a substantially
non-magnetic material with little or no magnetic permeability, the
teachings of which patents are incorporated herein by reference to
this end.
[0016] A material particularly suited for such a common or single
housing comprises aluminum and its alloys or thermoplastic formed
by casting or injection molding to required housing configuration
to receive the valve member 12 and the solenoid 14. The common
housing will include a housing section or region for enclosing the
solenoid 14 and a nozzle housing section or region for enclosing
the valve 12 and associated valve components.
[0017] Referring to FIG. 1, the solenoid 14 is disposed in the
solenoid housing 19b (or solenoid housing section of the common
housing embodiment) and includes an electromagnetic solenoid coil
16 wound about a cylindrical surface of molded plastic bobbin 18
which has a cylindrically shaped bore hole 20 through the
longitudinal axis thereof. The bobbin 18 is made of glass filled
thermoplastic. An axially elongated, generally cylindrical armature
22 formed of a ferromagnetic material (e.g. steel) is suspended
within the bore hole 20 of the plastic bobbin 18 by a thin low
spring rate spring 24 mounted at a rear, outermost end 22a of the
armature.
[0018] The plate spring 24 is of the type described in the
aforementioned Najmolhoda U.S. Pat. No. 4,988,074, the teachings of
which are incorporated herein by reference. That is, the spring
plate is formed from very thin non-magnetic austenitic stainless
steel, such as full hard austenitic stainless steel, which provides
a very low rate spring for the spring configuration shown in FIG. 5
of the aforementioned '074 patent. The inner periphery of the plate
spring 24 is mounted by half hard brass plate annular retainer
member 23 and half hard brass annular retainer 27 mounted to the
rear, outer end 22a of the armature 22 so as to suspend the
armature 22 for free axial longitudinal movement within the bobbin
18. The opposite front, inner end 22b of the armature is supported
by a similar optional plate spring 26. The plate spring 26 may be
omitted from the embodiment of FIG. 1 with the inner end 22b of the
armature 22 unsupported, except by the axial periphery of damping
member 25 received in damping chamber 80 as described below.
[0019] The outer periphery of the plate spring 24 is mounted
between the radially enlarged annular end flange 18h of the coil
bobbin 18 and an opposing annular end of valve housing cap or
closure 46 made of aluminum alloy (e.g. Al alloy 6061 T6). The
solenoid housing 19a includes an annular end flange 19e overlying
the cap or closure 46 as shown with a Bellvelle wave washer 47
therebetween to accommodate stack up tolerances.
[0020] As shown in FIG. 1, an inner end 22b of the armature 22
cooperates with a fluid damping member 25 that, in turn, engages a
steel ball valve 38. Ball valve 38 cooperates with annular valve
seat 21a on a ball valve cage insert 21 pressed in the valve or
nozzle housing 19a. The ball valve 38 and valve seat 21a define a
fluid diverting valve for diverting fluid to exhaust ports 74 in a
manner described below. The cylindrical axial shaft section 25a of
damping member 25 is pressed into a cylindrical counterbore in the
inner end 22b of the armature 22 as shown so as to be coaxial with
the armature 22 and to fix the damping member thereon. An optional
carbon steel flux washer W can be provided in a recess in bobbin 18
pursuant to aforementioned U.S. Pat. No. 4,988,074, incorporated
herein by reference, to concentrate electromagnetic flux at the
inner end of the armature.
[0021] An axially magnetized ring magnet 34 is disposed in an
annular recess 36 at the rear end of the bobbin 18 axially rearward
of the solenoid coil 16. Ring magnet 34 is formed of rare earth
permanent magnet material, such as Sm--Co or Nd.sub.2Fe.sub.14B,
permitting use of a reduced size magnet that results in a compact
solenoid. Ring magnet 34 produces a permanent magnetic field that
substantially saturates the armature 22 even in the absence of
electrical current to the coil 16. Thus, a relatively smaller
magnetic field is required to move the armature 22 between the
axial position shown in FIG. 1 corresponding to a valve closed
position (where ball valve 38 is seated on the valve seat 21a) and
an axial position to the left in FIG. 1 corresponding to a valve
open position (where ball valve 38 is unseated from the valve seat
21a).
[0022] The ball valve 38 is received and confined laterally in a
flat-sided recess or cage machined or otherwise formed in the
stainless steel insert 21 as shown between the inner end of the
armature 22 and the valve seat 21a. In this valve arrangement, the
ball valve 38 is biased by coil spring 42 against the armature end
22b and follows movement of the armature 22 in a direction toward
or away from the valve seat 21a by virtue of the fluid pressure on
the ball valve and by virtue being captured in the insert 21.
[0023] Coil compression spring 42 (spring biasing means) is trapped
in a cylindrical armature counterbore between the axial armature
end 22a and a central axially extending projection 46a of the valve
housing cap or closure 46. The projection 46a receives the coil
spring 42 with the end of the spring 42 engaging the inner surface
or wall of the cap 46. The armature 22 is biased to the valve
closed position by the coil spring 42 when the solenoid coil 16 is
deenergized. The cap or closure 46 includes a cylindrical outer
surface received in a cylindrical counterbore of the bobbin 18 to
trap spring 24 as shown.
[0024] A plastic connector body 52 is mounted on the bobbin 18 and
exits the solenoid housing 19b via a suitable opening 19f therein.
Electrical contacts 54 (only one shown) extend through the bobbin
18 and through apertures in the connector body 52. Such electrical
contacts 54 are shown in the aforementioned Najmolhoda U.S. Pat.
No. 4,988,074. The ends of the electrical contacts 54 are connected
to the wires of the electromagnetic coil 16 for receiving an
electrical current signal from a variable current source (not
shown).
[0025] In accordance with one embodiment of the invention, the
armature damping member 25 includes a generally disk shaped section
25b disposed on shaft section 25a that is received in the inner
armature end 22b. The disk section 25b has a cylindrical recess or
cavity to form a cup-shaped disk end on the ball valve side thereof
to reduce mass and extends radially from the longitudinal axis of
the armature 22 and shaft section 25a. The armature damping member
can comprise a ferromagnetic material, such as steel, to provide an
improved magnetic flux carrier to direct the magnetic flux directly
into the armature end 22b, while reducing size of the solenoid
unit. The armature damping member 25 alternatively may comprise a
plastic material, such as glass filled thermoplastic, or other
non-magnetically permeable material, since the present invention is
not limited to any particular damping material. The cup-shaped disk
end or section 25b includes a cylindrical outer peripheral surface
25c that cooperates with cylindrical damping chamber 80 disposed in
the valve or nozzle housing 19a to reduce or dampen pressure
oscillations resulting from electrical, mechanical, and/or
hydraulic noise in the controlled fluid system or circuit; i.e. the
fluid system or circuit, such as an automatic transmission circuit,
controlled by valve 12. To this end, there is a controlled
clearance between the outer cylindrical, peripheral surface 25c of
the damping member 25 and the cylindrical chamber wall 80a. The
damping chamber 80 is machined or otherwise formed in the valve or
nozzle housing 19a and communicates with the exhaust ports 74 (two
shown with two additional exhaust ports not shown extending into
and out of the plane of the drawing).
[0026] In operation in an automatic transmission application where
the control valve is fully immersed in hydraulic transmission
fluid, the damping chamber 80 typically will have predominantly
hydraulic fluid therein, although some air may be present in the
damping chamber 80.
[0027] In accordance with an embodiment of the invention, the
cross-sectional area of the damping member 25 and the clearance
between the surface 25c and the cooperating wall 80a of the damping
chamber 80 are selected effective to reduce or damp pressure
oscillations resulting from noise in the controlled fluid system or
circuit, which pressure oscillations can result in non-linear valve
response performance. An exemplary cross-sectional area of the disk
section 25b (cross-sectional area calculated using the outer
diameter of damping member 25) can be 0.039 inch.sup.2 (0.54 inch
outer diameter of damping member disk section). For this exemplary
cross-sectional area of the damping member 25, an exemplary radial
clearance of approximately 0.005 inch can be provided between the
disk surface 25c and the chamber wall 80a for the proportional
variable force solenoid fluid control valve shown in FIG. 1 adapted
for use in a hydraulic automatic transmission application for
controlling a gear shifting hydraulic circuit. More generally, the
aforementioned radial clearance can be in the range of 0.004 to
0.0055 inch for a disc section outer diameter in the range of 0.540
to 0.542 inch and axial length of surface 25c in the range of 0.070
to 0.074 inch in a damping chamber having inner diameter of 0.550
to 0.551 inch to provide a damping area in the range of 0.0003 to
0.0004 inch.sup.2, although the invention is not limited in this
regard. In effect, the damping chamber 80 and the damping member 25
provide a trapped volume of fluid comprising predominantly
hydraulic fluid which must be moved through the restricted
clearance area between the surface 25c and the wall 80a and in
doing so reduces or damps pressure oscillations resulting from
electrical, mechanical, and/or hydraulic noise in the controlled
fluid system or circuit.
[0028] The valve or nozzle housing 19a includes a longitudinal
passageway 66 having a generally cylindrical configuration for
receiving an aluminum alloy spool 67 (e.g. Al alloy 6262) which is
received in the passageway 66 in a close fit, sliding manner at
spool end regions for axial reciprocable movement.
[0029] The housing 19a is disposed in a bore or chamber (not shown)
in a cast aluminum transmission body (not shown) or other fluid
control system. Outer O-ring seals S1, S2 on the valve housing 19a
seal on the transmission housing and separate the supply and
control lines or conduits (not shown) of the transmission hydraulic
circuit.
[0030] The valve housing 19a includes a pressurized fluid supply or
inlet port 72, a plurality of control ports 83, a plurality of
first exhaust ports 81 associated with the control ports 83, and a
plurality of second exhaust ports 74 associated with the ball valve
38. The valve housing 19a includes the damping chamber 80
communicated with the ball valve 38 and in turn the respective
exhaust ports 74. These ports can be cast, machined or otherwise
formed in the valve housing 19a. The control ports 83, exhaust
ports 81, and exhaust ports 74 are spaced circumferentially about
the nozzle section 19a. Typically, two control ports 83, four
exhaust ports 81, and four exhaust ports 74 are provided on the
valve housing 19a. A tubular fluid filter screen assembly FSA is
held on the nozzle housing 19a by retainer 75 and sealed thereto by
O-ring 77. The assembly includes filter screens F overlying the
inlet and control ports 72, 83 as shown to permit fluid flow
through overlying openings OP in the filter support ring R and
prevent entry of harmful dirt and debris particles that may be
present in the fluid. The filter screens F are carried on the
support ring R.
[0031] The inlet port 72 communicates with an annular chamber 73
that, in turn, is in communication with a radial fluid passage 67a
of the spool 67. Passage 67a communicates with a longitudinal
central passage 67b of the spool 67 having an orifice plug 67h
press fit therein.
[0032] The slidable spool valve 67 is disposed in the valve housing
19a to provide a two stage operation wherein, in the first stage,
pressurized fluid is supplied to the inlet or supply port 72 with
the inner end 67c of the spool valve abutted against housing stop
end wall (proximate insert 21) as shown in FIG. 1 as biased by
spring 68 and with the ball valve 38 seated against the valve seat
21a with no electrical current to the coil 16. Spring 68 abuts an
end closure 69. As a result, the entering fluid flow is caused to
bypass the control ports 83 and instead is directed to flow through
spool passages 67a, 67b and orifice plug 67h to the axial fluid
passage of valve insert 21. The ball valve 38 initially is seated
on the valve seat 21a by virtue of the force of the coil spring 42.
The position of the spool valve 67 corresponding to a minimum fluid
flow spool valve position relative to the control ports 80 occurs
when the annular spool control land 67e is not communicated to the
inlet port 72. However, once the fluid reaches valve seat 21, fluid
pressure increases to a level that moves the spool valve 67 to the
right in FIG. 1 against spring 68 sufficiently to communicate the
annular control land 67e to the inlet port 72 with exhaust ports 81
closed. This position of the spool valve 67 corresponds to a
maximum fluid flow spool valve position relative to the control
ports 83 wherein the annular spool control chamber is communicated
to the inlet port 72. Communication of the spool control land 67e
with the inlet port 72 also communicates the end 67d of the spool
valve 67 to the control pressure port 83 via the passage 67g. Thus,
when the steady state flow conditions are realized, the opposite
ends of the spool valve 67 are subjected to equal fluid
pressure.
[0033] Thereafter, a second stage of operation involves controlling
the fluid flow through the control ports 83 by spool valve movement
between the aforementioned minimum and maximum flow spool
positions. Movement of the spool valve is controlled by diverting
fluid from the valve seat 21a out through the exhaust ports 74 to
vary fluid pressure in a linear proportional manner. For example,
electrical current is supplied to the coil 16 via the contacts 54
to create an electromagnetic field which, in addition to the force
of fluid pressure on the ball valve 38, overcomes the coil spring
42 and slight force of spring plate 24 to move the armature 22 in a
linear proportional manner to the current level applied to coil 16.
Since the ball valve 38 moves with the armature 22, the ball valve
38 will open in linear proportional manner to the current applied
to the coil 16 and divert fluid out of the exhaust ports 74 to
unbalance fluid pressure on the spool valve member ends to control
the spool valve position in linear proportional manner between the
aforementioned minimum and maximum fluid flow spool positions
relative to the control ports 83 and exhaust ports 81 of the valve
housing 19a. This provides a controlled fluid flow out of the
control ports 83 in direct proportion to the opening of the ball
valve 38 in accordance with linear movement of the armature 22
which, in turn, is directly proportional to the amount of
electrical current supplied to the coil 16 of the solenoid 14.
[0034] Such axial spool movement as described hereabove provides a
negative gain mode of fluid flow control wherein there is a linear
decrease in fluid pressure at the control ports 83 in proportion to
an increase in electrical current to the coil 16. However, a
positive gain mode of fluid flow control also can be achieved by
the proportional variable force fluid control valve 10 described by
reversing the flow of electrical current in the coil 16 and by
introducing supply pressure through the inlet port 72 with the ball
valve 38 in the full open position as determined by the position of
the armature 22 with current flowing in the coil 16 as described in
aforementioned U.S. Pat. No. 5,611,370.
[0035] Regardless of whether the proportional variable force
solenoid control valve 10 is operated in a positive or negative
gain mode, the armature disk 25 and damping chamber 80 will
cooperate to reduce or dampen fluid pressure oscillations resulting
from electrical, mechanical, and/or hydraulic noise in the
controlled fluid system or circuit, which pressure oscillations, in
turn, can result in non-linear valve response behavior. In an
electronically controlled automobile transmission application,
electromechanical noise in the controlled system or circuit can
originate in the transmission control module (e.g. a chopped pulse
width control signal) and oscillations of the clutch or shift
valves in the transmission body and produce fluid pressure
oscillations and a non-linear valve response.
[0036] Referring to FIG. 2, another embodiment of the invention is
illustrated wherein like reference numerals primed are used to
designate like features of FIG. 1. The embodiment of FIG. 2 differs
from that of FIG. 1 in that the disk-section 25b' of the damping
member 25' is not cup-shaped, but rather is provided with a flat
disk configuration shown with a cylindrical outer surface 25c'
cooperating with cylindrical wall 80a' of chamber 80' as described
above. Plate spring 26 of FIG. 1 is not present in FIG. 2. The
armature damping member 25' is received in chamber 80' in the
manner described hereabove for FIG. 1 to cooperate with the chamber
80' to reduce or dampen fluid pressure oscillations resulting from
noise in the controlled fluid system or circuit.
[0037] Referring to FIG. 3, still another embodiment of the
invention is illustrated wherein like reference numerals double
primed are used to designate like features of FIG. 1. The
embodiment of FIG. 3 differs from that of FIG. 1 in that the
damping member 25" is separate from the armature 22" and is not
connected thereto. Rather, the separate cup-shaped damping member
or disk 25" residing in cylindrical damping chamber 80" is engaged
by a cylindrical plug 27" fixedly press fit in the inner end 22b"
of the armature as illustrated. The plug 27" includes a rounded
nose 27a" to provide an approximate point contact with the damping
member or disk 25" to this end. The armature damping member or disk
25" is received in chamber 80' in the manner described hereabove
for FIG. 1 so that its cylindrical outer surface 25c" cooperates
with the cylindrical chamber 80' to reduce or dampen fluid pressure
oscillations resulting from noise in the controlled fluid system or
circuit. The embodiments of FIGS. 2 and 3 operate in a manner
similar to the the embodiment of FIG. 1 to control fluid pressure
and improve valve response stability to pressure oscillations in
the controlled fluid system by virtue of cooperation between the
damping member 25', 25" and respective damping chamber 80',
80".
[0038] In the above described embodiments of the invention, the
spool spring 68, 68', 68" may be omitted and fluid pressure used to
bias the spool as described in aforementioned U.S. Pat. No.
5,611,370, already incorporated herein by reference.
[0039] Although certain preferred embodiments of the proportional
variable force solenoid valve and fluid control device for an
electronic transmission of the invention have been shown and
described in detail, it should be understood that variations or
modifications may be made without departing from the spirit or
scope of the present invention.
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