Single stage variable force solenoid pressure regulating valve

A pressure regulating variable force solenoid fluid control valve for regulating the pressure of a pressurized fluid in a fluid control system in proportion to the current level of an electrical input signal comprises a supply port for receiving pressurized fluid, a control port in fluid flow communication to the supply port via a primary orifice, the control port communicating with an external component, such as a hydraulic automobile transmission component to control operation thereof, and a variable force solenoid actuated valve that cooperates with a valve seat receiving pressurized fluid from the primary orifice to control flow of pressurized fluid to one or more exhaust ports as a means to regulate pressure at the control port in dependence upon electrical current to a coil of the solenoid actuated valve. A secondary bleed orifice is provided in a position between the supply port and the control port remote from the valve seat and proximate the control port to bleed pressurized fluid to the control port in a manner to provide more precise low pressure fluid control, for example, particularly at or near zero gage (control) pressure, over wide fluid pressures and temperatures and reduce negative pressures that can be generated proximate the valve seat when the valve is opened.

FIELD OF THE INVENTION 
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 pressure 
regulating proportional variable force solenoid having multiple ports to 
provide more precise low pressure control over wide operating fluid 
pressures and temperatures. 
BACKGROUND OF THE INVENTION 
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 nozzle joined 
together mechanically such as by tabs on the steel solenoid housing being 
crimped about regions of the aluminum valve member nozzle. 
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. The fluid control valve on the end of the armature moves relative 
to a valve seat disposed in the aluminum valve nozzle 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. 
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 nozzle. 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. 
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. 
An object of the present invention is to provide a variable force solenoid 
fluid pressure regulating valve having improved low pressure control (e.g. 
at or near zero gage pressure) over wide operating pressures and 
temperatures. 
Another object of the present invention is to provide a variable force 
solenoid fluid pressure regulating valve having mulitple orifices to 
improve low pressure control (e.g. at or near zero gage pressure) with 
stability over wide operating pressures and temperatures of valve 
operation. 
SUMMARY OF THE INVENTION 
The present invention provides a pressure regulating variable force 
solenoid fluid control valve for regulating 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 
pressure regulating variable force solenoid fluid valve comprises a supply 
port for receiving pressurized fluid, a control port in fluid flow 
communication to the supply port via a primary orifice. The control port 
communicates with an external fluid actuated component, such as a 
hydraulic automobile transmission component, to control operation thereof. 
The valve includes a variable force solenoid actuated valve that 
cooperates with a valve seat receiving pressurized fluid from the primary 
orifice to control flow of pressurized fluid to one or more exhaust ports 
as a means to regulate pressure at the control port in dependence upon 
electrical current to a coil of the solenoid actuated valve. A secondary 
bleed orifice is provided in a position between the supply port and the 
control port preferably proximate the control port in one embodiment of 
the invention to bleed pressurized fluid to the control port in a manner 
to provide more precise low pressure fluid control, for example, 
particularly as control port gage pressure approaches zero gage (control) 
pressure, over wide range of fluid pressures and temperatures. In 
particular, the secondary bleed orifice is effective to substantially 
eliminate negative pressure at the control port as control gage pressure 
approaches zero. 
In a particular embodiment of the present invention, the pressure regulatng 
valve includes a first supply orifice downstream of the supply line 
connection to initially adjust supply fluid pressure. The supply orifice 
communicates to an internal passage of a sleeve that separates the supply 
port from the control port so as to supply pressurized fluid to the sleeve 
passage. The sleeve includes a primary orifice at an end proximate the 
valve seat for providing pressurized fluid from the sleeve passage to the 
control port and a secondary bleed orifice in a wall of the sleeve 
proximate the control port, although the bleed orifice can be disposed at 
other locations to achieve the advantages of more precise low pressure 
control discussed above. 
The solenoid that actuates the valve may optionally comprise an armature in 
engagement with the valve and movable in response to electrical current 
applied to a solenoid, spring 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), 
and a valve housing closure that engages the spring means and that is 
permanently deformed after valve assembly to position the valve housing 
closure relative to the spring means in a manner to adjust the valve fluid 
pressure response to a desired performance specification. 
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.

DESCRIPTION OF THE INVENTION 
Referring to FIGS. 1-2, a proportional variable force solenoid fluid 
control valve 10 includes a can or housing 12 and a nozzle 19 with the can 
or housing 12 enclosing solenoid components for actuating a valve 
mechanism in a manner to be described below. The can or housing 12 
preferably comprises steel or other magnetically permeable material. The 
nozzle 19 preferably comprises a substantially non-magnetic material 
having little or no magnetic permeability, for example, as compared to the 
magnetic permeability of a ferromagnetic material, such as steel. A 
material particularly suited for the nozzle 19 comprises aluminum and its 
alloys or thermoplastic formed by casting or injection molding to required 
configuration to receive the solenoid actuated valve components to be 
described. 
The solenoid actuated fluid control valve 10 includes a solenoid 14 
comprising an electromagnetic coil 16 wound about a 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. A 
rod-like steel armature 22 is suspended within the bore hole 20 of the 
plastic bobbin 18 by first and second thin low spring rate springs 24a, 
24b. 
The plate springs 24a, 24b are of the type described in U.S. Pat. No. 
4,988,074, the teachings of which are incorporated herein by reference. 
That is, the spring plates are 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 outer periphery of the 
first plate spring 24a is mounted between a flange of bobbin 18 and 
flanged section 19a of the nozzle 19. The inner periphery of the first 
plate spring 24a is mounted between the armature 22 and an armature plug 
22a made of steel. 
The outer periphery of the second plate spring 24b is mounted between a 
flange of the bobbin 18 and an end closure 46. The inner periphery of the 
second plate spring 24b is mounted between a first collar 27 affixed to 
the armature 22 by press fit and made of brass and a second collar 29 
press fit in the first collar 27 and made of brass. By use of the spring 
plates 24a, 24b, the armature 22 is suspended for free axial longitudinal 
movement within the bobbin 18. 
The armature 22 comprises a flat outermost axial end having a counterbore 
22b that receives a coil compression spring 42 for biasing the the 
armature 22 to the right in FIG. 2. The coil compression spring 42 (spring 
biasing means) is trapped between the axial armature end and a central hub 
46a of the valve housing cap or closure 46. The central hub 46a includes 
an inwardly, axially extending cylindrical spring locating projection or 
stud 46a' that receives the coil spring 42 with the end of the spring 42 
engaging the inner surface or wall of the central hub 46a as shown in FIG. 
2. The armature 22 is biased to a valve closed position by the coil spring 
42 when the solenoid electromagnetic coil 16 is deenergized. 
The valve housing cap or closure 46 is deformable in a manner to adjust the 
force exerted by the coil spring 42 on the armature 22 and thus the valve 
fluid pressure response to electrical current level supplied to the 
solenoid 14 (i.e. fluid pressure versus solenoid current). In particular, 
the force exerted by the coil spring 42 on the armature 22 is adjusted 
using an adjustment tool to provide a desired bleed rate of fluid past 
ball valve 38 or cracking pressure of the ball valve 38 in a manner 
described in copending patent application Ser. No. 08/586,056 of common 
assignee herewith to provide a desired fluid pressure versus solenoid 
current response. The housing closure 46 includes a peripheral region 46b 
engaged by an end region of the can or housing 12 such that the central 
hub 46a engages the spring 42. The closure 46 comprises machined aluminum 
alloy. 
The closure 46 is deformable in a region defined by an annular recessed or 
grooved region 46d that encircles central flat closure hub 46a. The 
recessed or grooved region 46d is disposed concentrically about the 
central hub 46a between the hub 46a and the peripheral lip 46c. The 
annular recessed or grooved region 46d has a relatively smaller 
cross-section, FIG. 2, as compared to the peripheral region 46b. The 
central hub 46a typically suffers the primary or majority of permanent 
deformation by engagement with the adjustment tool to permit axial 
adjusting movement of the hub 46a relative to the peripheral region 46b, 
although the grooved region 46d also may undergo some deformation to this 
same end. The grooved region 46d helps to confine the majority of 
deformation to the central hub 46a. The central hub 46a is permanently 
adjusted in axial position after the closure 46 is secured to the valve 
housing 19 to adjust the valve response. 
An axially magnetized permanent ring magnet 41 is held in position relative 
to the coil 16 by a bobbin retainer flange 18a. The ring magnet 41 thereby 
is disposed at the rear end of the bobbin 18 axially rearward of the coil 
16. Ring magnet 41 is formed of rare earth permanent magnet material 
permitting use of a reduced size magnet that results in a compact solenoid 
and enhanced stability, such as reduced loss of magnetism at elevated 
temperatures. The ring magnet 41 produces a permanent magnetic field that 
substantially saturates the armature 22 even in the absence of electrical 
current to the coil 16. A steel washer 43 is disposed proximate the coil 
16 and armature 22 to concentrate magnetic flux. Thus, a relatively 
smaller electromagnetic field is required to move the armature 22 between 
axial positions coresponding to valve "on" and "off" states where the "on" 
state provides a zero supply gage pressure at control port CP and the 
"off" state provides full pressurized fluid at control port CP. 
The proportional variable force solenoid control valve described using a 
ring magnet in combination with a electromagnetic coil is described in 
U.S. Pat. No. 4,988,074 and copending patent application Ser. No. 
08/337,613 (allowed), the teachings of which are incorporated herein by 
reference. 
A plastic connector body 52 shown in FIG. 2 is mounted on the bobbin 18 and 
exits the can or housing 12 at a side thereof. The connector body 52 
includes electrical contacts 54 that are used to provide electrical 
current to the coil 16. The electrical contacts 54 extend through the 
bobbin 18 and through apertures in the connector body 52. Such electrical 
contacts 54 are shown in the aforementioned 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). 
The can or housing 12 includes inwardly extending, annular end shoulders 
23a, 23b to confine the solenoid components in the housing 12 and connect 
the nozzle 19 to the can or housing. An annular spring washer 23c is 
provided to securely locate the solenoid components by accommodating 
tolerance stackups. 
As shown in FIG. 2, the innermost armature plug 22a of the armature 22 
engages an elastomeric or metal ball valve 38 that cooperates with a valve 
seat 18d formed on the valve seat insert 18 residing in the nozzle 19. The 
ball valve 38 and valve seat 18d define a fluid diverting or exhausting 
valve for diverting or exhausting fluid to one or more exhaust ports EP in 
a manner described herebelow that can be communicated to a fluid sump or 
return (not shown). 
The ball valve 38 is received and confined laterally in a flat-sided recess 
18e of the valve seat insert 18 between the innermost armature plug end 
22a and the valve seat 18d. In this valve arrangement, the ball valve 38 
is biased against the armature plug end 22a and follows movement of the 
armature 22 in a direction toward or away from the valve seat 18d by 
virtue of the fluid pressure on the ball valve and by virtue being 
captured in the recess 18e. 
The nozzle 19 includes a nozzle section 19a joined to the can or housing 12 
by crimped can shoulders 23b and that includes O-ring seals 19b, 19c for 
sealing on the components of the mating fluid control system, such as on 
an automatic transmission valve body. The seal 19c sealingly separates a 
supply line or chamber SL and control line or chamber CL as schematically 
illustrated in FIG. 2. The control line or chamber CL typically is 
communicated to a downstream component (not shown) external of the 
pressure regulating valve described hereabove to control operation 
thereof. The component can be a line pressure control valve of an 
automobile automatic transmission for purposes of illustration and not 
limitation. The supply line or chamber SL is communicated to a source of 
pressurized fluid, such as a hydraulic fluid pump (not shown). 
The nozzle 19 includes a fluid filtering screen S1 for removing dirt or 
debri from fluid entering the nozzle section 19a via the supply port SP. 
The nozzle 19 also includes a fluid filtering screen S2 for removing dirt 
or debri from fluid exiting the nozzle section 19a via the control port 
CP. The filtering screens S1, S2 are held in position on the nozzle 19 by 
a tubular molded plastic filter support member 21 having windows 21a 
exposing the screens S1, S2. O-ring seal 19b resides on the support member 
21, while O-ring seal 23 resides between nozzle 19 and support member 21. 
A filter retainer 69 made of plastic material is provided to lock the 
filter and support member in position. 
The nozzle 19 includes a longitudinal passageway 66 having a cylindrical 
configuration for receiving a fixed sleeve 68. The nozzle 19 is machined 
to include a first orifice O1 that is sized in diameter to initally adjust 
supply pressure entering the passageway 66. The passageway 66 is closed at 
the end remote from the solenoid by a closure cap 66a. 
Fixed sleeve 68 is received in the nozzle in a close fit, sealed manner. 
The sleeve 68 includes an open axial end 68a that receives pressurized 
fluid from the orifice O1 and an inner passageway 68b having radially 
stepped down sections for ease of manufacture with the stepped down 
section 68b terminating in a primary orifice O2 that is disposed opposite 
and proximate the valve seat insert 18 in a chamber C. In particular, the 
primary orifice O2 is located axially spaced from the valve seat 18d 
defining flat-sided fluid exhaust recess 18e through which pressurized 
fluid is exhausted to exhaust ports EP to regulate fluid pressure at 
control port CP. The exhaust ports EP are disposed on the housing 19 
proximate the ball valve 38 as shown in FIG. 2 and communicate with an 
exhaust sump or return (not shown). Four circumferentially spaced exhaust 
ports EP can be used but the invention is not limited to this end as any 
number or such ports can be used. 
Pressure regulation is achieved by movement of the armature 22 in response 
to electrical current to the coil 16 to exhaust pressurized fluid from 
chamber C. When no current is provided to the coil 16, the spring 42 
biases the ball valve 38 to close on valve seat 18d ("off" state). The 
control port CP receives the pressure present at valve seat 18d at this 
time. When the coil 16 is energized by a maximum selected electrical 
current, the armature 22 is moved away from the valve seat 18d to the 
maximum extent ("on" state) to allow ball valve 38 to fully open and 
provide a zero or near zero fluid gage pressure at control port CP. 
Movement of the armature 22 between these positions is effected by varying 
the current to the coil 16 to vary the ball valve position relative to 
valve seat 18d and thus exhaust more or less pressurized fluid from 
chamber C to port(s) EP as needed to regulate fluid pressure at control 
port CP in the desired manner. 
A secondary bleed orifice O3 is provided in accordance with one embodiment 
of the present invention in a position between the supply port SP and the 
control port CP remote from the valve seat 18d and proximate the control 
port CP to bleed pressurized fluid to the control port CP in a manner to 
provide more precise low pressure fluid control, for example, as the 
control port pressure approaches zero gage (control) pressure. This 
improved low pressure control is provided over a wide range of fluid 
pressures and temperatures and reduces negative pressures that can be 
generated proximate the valve seat 18d in chamber C when the valve is 
opened. In FIG. 2, the secondary bleed orifice O3 is shown disposed 
directly opposite to the control port CP. However, the position of the 
bleed orifice O3 can be varied to other axial locations of the sleeve 68 
such as shown, for purposes of illustration and not limitation only, by 
dashed lines in FIG. 2. 
The secondary bleed orifice O3 is sized in diameter to bleed pressurized 
fluid to the control port CP when the ball 38 valve is opened in response 
to movement of the armature 22 by energization of the coil 16. The fluid 
bled from orifice O3 can counteract any slightly negative pressure that 
can be generated by venturi effects in the chamber C when the valve 38 is 
opened as pressurized fluid is exhausted to the exhaust ports EP and 
provide a more precise low pressure control over wide operating fluid 
pressures and temperatures. 
The ratio of the areas of the supply orifice O1, primary orifice O2, and 
secondary bleed orifice O3 is controlled to this end to minimize "off" 
(i.e. fluid pressure at control port CP approaching zero gage) pressure 
variations at the control port CP that result from such negative pressure 
in chamber C and variations in supply line pressure. For purposes of 
illustration and not limitation, the ratio of the cross-section areas of 
the cylindrical supply orifice O1, primary orifice O2, and secondary bleed 
orifice O3 can be controlled at 1.25:1.25:1.00 for operation under fluid 
supply pressures in the range of 40 to 250 psi where fluid exhaust opening 
18e defined by the valve seat 18d has an area of 0.0035 square inches and 
is axially positioned about 0.100 to 0.180 inches (distance D1) from the 
orifice O2. 
FIG. 3 represents a graph of control pressure versus electrical current to 
the solenoid coil for a single stage pressure regulating proportional 
variable force solenoid fluid pressure regulating valve in accordance with 
the embodiment of the invention described hereabove. It is apparent that 
precise low pressure control at or near zero gage pressure at control port 
CP is provided at different supply line pressures of 45, 150 and 250 psi. 
In contrast, FIG. 4 is a graph of control pressure versus electrical 
current for a single stage pressure regulating proportional variable force 
solenoid fluid valve of similar construction but without a secondary bleed 
orifice. The loss of precise low pressure control and generation of 
negative pressures at the control port CP at different supply line 
pressures of 45, 150 and 250 psi are evident. 
FIG. 5 illustrates another embodiment of the invention having a different 
arrangement of valve components and supply and control ports. In FIG. 5, 
like or similar features of FIGS. 1-2 are represented by like reference 
numerals double primed. The embodiment of FIG. 5 differs from that of 
FIGS. 1-2 in that the control port CP" and supply port SP" are reversed in 
axial position on the nozzle 19". The sleeve 68" includes a ball 68b" that 
is fixed in position to plug or close the open sleeve end 68a" so that 
pressurized fluid (e.g. hydraulic fluid) entering the supply port SP" 
flows through orifice O1" through a sleeve opening 68c" and through 
primary orifice O2" to the chamber C". Pressurized fluid that exits the 
primary orifice O2" flows from chamber C" to the control port CP" via side 
scallops or recesses 68d" formed in the sleeve 68" as shown in FIG. 5A. 
The ball valve 38" functions in the same manner as in the ball valve 38 of 
embodiments of FIGS. 1-2 to exhaust pressurized fluid from chamber C" via 
exhaust ports EP" in response to movement of the armature 22" determined 
by the electrical current provided to the coil 16". 
The secondary bleed orifice O3" is disposed through the sleeve wall between 
the orifice O2" and supply opening 68c" for functioning in a manner as 
described for secondary bleed orifice O3 of FIGS. 1-2. 
Although certain preferred embodiments of the pressure regulating solenoid 
valve 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.