ELECTRO-HYDRAULIC POPPET VALVE WITH
SUPPLY PRESSURE UNLOADING FUNCTION
TECHNICAL FIELD
[0001] The present invention relates generally to electro-hydraulic solenoid
valves, and in particular to a solenoid valve having one or more internal poppet-style
valve devices.
. BACKGROUND OF THE INVENTION
[0002] A solenoid control valve configured for use within an electro-hydraulic
fluid control system or fluid circuit can be used to selectively control a flow of oil or
other fluid under pressure. Poppet valve assemblies (PVAs) include a cylindrical internal
chamber and a tapered or shaped poppet device such as an armature, a ball, or another
suitable device. Fluid under pressure is admitted into a valve body portion of the PVA in
response to an energizing of a solenoid portion of the PVA. The application of hydraulic
and/or magnetic force moves or actuates the poppet device, or multiple poppet or other
valve devices, within the internal chamber. Fluid paths therewithin are thus selectively
opened to permit fluid flow through various passages of the valve body in order to feed
various downstream fluid circuit loads.
[0003] Within a PVA, fluid sealing integrity largely depends on the closeness and
quality of the mating surfaces of the poppet and valve seat. As a result, some fluid
leakage or bypass is ordinarily encountered. Depending on the particular configuration
of the poppet device and downstream fluid circuit control system, fluid leakage can vary
from somewhat minimal to relatively substantial. The leakage performance of
conventional poppet valves and associated control fluid circuitry therefore can be less
than optimal. In some hydraulic systems, it would be desirable to unload the supply
pressure from a PVA in order to accurately quantify the leakage of the PVA and
downstream fluid circuit, In such systems, it is also desirable to minimize the parasitic
fluid losses and the cost to implement it. The present invention serves to fulfill these

SUMMARY OF THE INVENTION
[0004] A valve assembly according to one embodiment of the invention has a
solenoid portion with an energizable coil and a valve body connected thereto. The valve
body contains a valve device having an armature positioned adjacent to the coil and a
lower valve that is axially-aligned with the armature. The armature and its valve seat
may be collectively referred to as the "upper valve" to denote its downstream position
relative to the lower valve. The armature is biased by a resilient member, such as a
spring or another suitable return device, and extends axially within a chamber of the
valve body toward the lower valve. The lower valve may be configured as a spool valve
in one embodiment and a ball poppet in another embodiment, although other suitable
valve devices can also be used without departing from the intended scope of the
invention.
. [0005] The solenoid coil can be selectively energized using an energy supply
such as a battery, an electrical outlet, or any other available energy supply to move the
armature from a first position to a second position, thereby admitting fluid into the valve
body via a supply port. Movement of the armature allows the fluid to pass between the
lower valve and a lower valve seat and then between the armature and an upper valve
seat. The fluid is ultimately discharged from the valve body via a control port where it is
delivered to a downstream fluid circuit, e.g., a hydraulic machine and/or process, an
automotive system, and/or other hydraulic component or device.
[0006] When the valve assembly is closed, which can occur when the coil is in
either a de-energized or an energized state as desired, the armature is biased to seal
against the upper valve seat. An end of the armature contacting a surface of the lower
valve moves the lower valve to at least partially open one or more orifices in the valve
body. The orifice vents fluid from the valve assembly, for example to a low-pressure
tank or sump external to the valve body, and thus provides a pressure unloading function
downstream of the supply port as described herein. Fluid bypass or leakage past the
upper valve seat and into the downstream control circuit is thus substantially minimized.

Thus, fluid leakage or pressure decay downstream of the valve assembly can be more
precisely detected while parasitic losses in the energized state are sufficiently minimized.
[0007] The above features and advantages and other features and advantages of
the present invention are readily apparent from the following detailed description of the
best modes for carrying out the invention when taken in connection with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic illustration of a fluid circuit having a valve assembly
in accordance with the invention;
[0009] FIG. 2 is a schematic cross-sectional illustration of a valve assembly
usable within the fluid circuit of FIG. 1 and having a pair of internal valves each in a
closed position;
[0010] FIG, 3 is a schematic cross-sectional illustration of the valve assembly of
FIG. 2 in an open position;
[0011] FIG. 4 is a schematic cross-sectional illustration of a valve body portion of
an alternate valve assembly in a closed position; and
[0012] FIG. 5 is a schematic cross-sectional illustration of the valve body portion
of the alternate valve assembly of FIG. 4 in an open position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0013] Referring to FIG. 1, a fluid circuit 10 includes a low-pressure tank,
reservoir, or fluid sump 12 and a pump (P) 14. The sump 12 contains fluid 16, which is
drawn by the pump 14 and delivered under pressure (P1) via a supply line 26 to a
solenoid-operated valve assembly (VA) 18. The valve assembly 18 is electrically
connected to an energy source 28, also labeled ES in FIG. 1, e.g., a battery, a capacitor,
or other suitable electrical or electro-chemical storage device, or an electrical outlet, via a
wireless or hard-wired electrical connection 30.
[0014] Control logic (not shown) can be implemented to selectively open and
close the valve assembly 18 as needed to power a set of fluid components 32, such as but

not limited to hydraulic machinery, valves, pistons, accumulators, or other fluid circuit
devices. The fluid components 32 in turn are in fluid communication with the sump 12
via a return line 34. A pressure transducer 11 can be positioned downstream of the valve
assembly 18 to sense pressure decay in a downstream circuit portion 13 of the fluid
circuit 10.
[0015] The fluid 16 is admitted into the valve assembly 18 via the supply line 26
at the supply pressure (PI) through a supply port 20. When the valve assembly 18 is
turned on, which in a normally-closed device occurs when the valve assembly 18 is
selectively energized, the fluid 16 admitted into the valve assembly 18 is ultimately
discharged from the valve assembly 18 via a control port 22 at a control pressure (P2).
At least one orifice 23 is in fluid communication with the sump 12 via another return line
39 to provide a pressure unloading feature as set forth below with reference to FIGS. 2 -
5. While a single orifice is shown in the various Figures for simplicity, additional
orifices 23 can also be used within the scope of the invention. The number of orifices 23
used may be determined by the amount of available valve stroke, orifice size, and leakage
past a lower valve 24 in the open and closed positions as explained below.
[0016] Referring to FIG. 2, the valve assembly 18 is shown in a closed position,
blocking passage of a pressure (PI) to the control port 22. The valve assembly 18
includes a solenoid portion 36 and a valve body 38. The solenoid portion 36 is
electrically connected to the energy source 28 of FIG. 1, as shown in that Figure. In this
embodiment, when the solenoid portion 36 is de-energized in a normally-closed
configuration, fluid 16 is blocked from reaching the control port 22. That is, fluid 16 is
prevented from being discharged from the valve body 38 via the control port 22, which
can be disposed in a wall 76 thereof. In this manner, the control pressure (P2) (see FIG.
3) at the control port 22 is not made available for use by the components 32 shown in
FIG. 1.
[0017] The valve assembly 18 can be configured as an electro-hydraulic device,
and may include a solenoid housing 40 that contains a solenoid winding or coil 41. The
coil 41 is wound on a bobbin 43, and can be selectively energized to actuate or power the
valve assembly 18. That is, when the coil 41 is de-energized, the valve assembly 18

restricts fluid communication between the supply port 20 and the control port 22. When
the coil 41 is energized, a magnetic field is induced, thus generating magnetic flux which
ultimately opens the valve assembly 18 to allow flow from the supply port 20 to the
control port 22 as shown in FIG. 3 and described below.
[0018] In addition to the control port 22, the valve body 38 includes an inner wall
44 defining an upper chamber 42 that defines an upper valve seat 46. An armature 48
moves axially within the upper chamber 42 in the direction of arrow C absent a magnetic
field as described above. A resilient member 50 such as a spring or other suitable return
device can be positioned between a first end 51 of the armature 48 and an undersurface
54 of a pole portion 55 to react against the undersurface 54, and to thereby provide a
sufficient return force for moving the armature 48 in the direction of arrow C when the
solenoid portion 36 is de-energized as shown in FIG. 2.
[0019] The armature 48 is disposed in a magnetic sleeve 15 to move in
conjunction therewith. In one embodiment, the magnetic sleeve 15 may circumscribe the
armature 48. The sleeve 15 is moveably disposed within the upper chamber 42 of the
valve body 38 and defines an air gap 47 with the undersurface 54 of the pole portion 55.
A second end 53 of the armature 48 is configured to seal against the upper valve seat 46
with a predetermined maximum rate of fluid bypass. The armature 48 extends axially
toward a lower chamber 56 of the valve body 38 and contacts a lower valve 24 through a
connecting port 33, with the connecting port 33 providing fluid communication between
the upper and lower chambers 42 and 56, respectively.
[0020] Still referring to FIG. 2, the volume of the lower chamber 56 is defined by
an inner wall 58, which contains or houses the lower valve 24. As shown in the
embodiment of FIGS. 2 and 3, the lower valve 24 can be configured as a spool valve.
However, other embodiments are possible without departing from the intended scope of
the invention, including but not limited to the ball poppet of FIGS. 4 and 5 described
below.
[0021] The valve body 38 also defines the supply force balance port 20A, within
which is disposed a stop device 60, e.g., an annular snap ring or other suitable spool-
retaining device. When the energy source 28 of FIG. 1 energizes the coil 41, the sleeve

15 is magnetically attracted toward the pole portion 55, and thus the armature 48 moves
axially in the direction of arrow 0 within the upper chamber 42. As a result, the force of
the resilient member 50 is overcome and the resilient member 50 compresses against the
undersurface 54 (see FIG..3). As the armature 48 moves in the direction of arrow 0, the
lower valve 24 is also free to move in the direction of arrow O in response to fluid
pressure at the supply force balance port 20A.
[0022] When the lower valve 24 is configured as a spool valve as shown in the
embodiment of FIGS. 2 and 3, the lower valve can include a spool 62 defining axial fluid
passages 64 therein. The spool 62 includes an extension 57 which contacts the armature
48, such that motion of the armature 48 can move the spool 62. When the valve
assembly 18 is in an open position as described below, the fluid 16 providing pressure
(PI) at the supply port 20, 20A can flow through the axial fluid passages 64, through the
connecting port 33, and into the upper chamber 42, where it is ultimately discharged
through the control port 22 to provide the control pressure P2. Fluid flow is thus
provided with minimal pressure drop across the valve assembly 18, which is preferably
less than approximately 0.5 bar(g).
[0023] At least one orifice 23 is disposed in the valve body 38 between the lower
valve 24 and the armature 48. As noted above, multiple orifices 23 can be used, or just
one as shown, depending on a variety of factors. The factors can include, but are not
necessarily limited to, available valve stroke, orifice size, allowable leakage past the
lower valve 24, etc. For example, one embodiment may include multiple orifices 23 that
are approximately equally spaced, e.g., four orifices 23 positioned 90 degrees apart from
each adjacent orifice 23. The orifices 23 can be sized as needed for a particular
application, e.g., approximately 0.5mm to approximately 1mm in diameter according to
another embodiment. In some applications, proper venting may not be achievable using a
single orifice 23. Also, leakage past the lower valve 24 can be difficult to predict.
Therefore, multiple orifices 23 may provided, with some of the orifices 23 plugged as
needed to tune the valve assembly 18 for a particular application.
[0024] More particularly, the orifice 23 may be formed within the wall 76 of the
valve body 38. The rate of fluid flow between the lower chamber 56 and the sump 12

(see FIG. 1) is thus limited by the orifice 23. In the open position shown in FIG. 3, the
orifice 23 is restricted by spool 62 and limits a flow of fluid 16, thereby reducing
parasitic fluid loss. The orifice 23 also reduces any appreciable pressure build up due to
any fluid leakage occurring past the lower valve 24 in the closed position of FIG. 2.
[0025] When the valve assembly 18 is in the closed position shown in FIG. 2, the
orifice 23 allows for venting of the valve assembly 18 by dumping fluid that leaks past
the spool 62. According to one embodiment, the upper valve seat 46 and the armature 48
are manufactured to have less than approximately 100 mg/min of fluid leakage or bypass
when in the closed position. Fluid leakage past the lower valve 24 in the closed position
can be several orders of magnitude higher and still provide an acceptable pressure
unloading function. The orifice 23 is configured with a diameter (d) that provides
optimal pressure unloading, In one embodiment, the diameter (d) of the orifice 23 is
approximately 0.5mm to approximately 1 mm. However, other diameter sizes can also
be used without departing from the intended scope of the invention.
[0026] As noted above, the orifice 23 should be large enough to reduce any
appreciable pressure buildup due to fluid leakage past the spool 62 in the closed position.
The orifice 23 is also sized small enough to reduce parasitic fluid loss to the sump 12
when the armature 48 and the lower valve 24 are in the open position shown in FIG. 3.
The diameter (d) should also be sized to sufficiently irnnirnize any pressure drop across
the valve assembly 18 when in the open position shown in FIG. 3.
[0027] Referring to FIG. 3, the valve assembly 18 in the illustrated embodiment is
open when the solenoid coil 41 is energized, thus allowing the fluid 16 to flow from the
port 20 to the control port 22. When a magnetic field is generated, the biasing force of
the resilient member 50 is overcome by fluid pressure to causes the armature 48 to move
in the direction of arrow O. As the armature 48 moves in the direction of arrow O, the
second end 53 thereof moves away from the extension 57. No longer opposed by the
armature 48, the lower valve 24 is free to move in the direction of arrow O to allow fluid
to flow from the port 20 to the control port 22. and to substantially block the orifice 23,
i.e., with at least approximately 75% of the orifice 23 being blocked in one embodiment.

[0028] FIGS. 4 and 5 illustrate another valve assembly 118 where the lower valve
24 is configured as a ball poppet. For simplicity, the solenoid portion 36 of FIGS. 2 and
3 is omitted from FIGS. 4 and 5, with the electro-mechanical structure and operation of
the solenoid portion 36 described above applying equally to the embodiment of FIGS. 4
and 5. The ball poppet could be used, for example, as a lower-cost device relative to the
spool design of FIGS. 2 and 3. However, a ball poppet may be expected to leak at a
higher rate relative to the spool design, and therefore a performance vs. efficiency
tradeoff may be a consideration in deciding between the particular embodiment to
employ in a given fluid circuit.
[0029] In the embodiment of FIG. 4, a sphere or ball 70 is biased towards a
closed position by the armature 48, for example via an axial arm or armature pin 48A,
which can be coupled to the armature 48 described above. A lower valve seat 71 is
shaped to form a fluid seal with respect to the ball 70 when the armature pin 48A pushes
the ball 70 against or near the lower valve seat 71 as shown in FIG. 4.
[0030] The lower valve seat 71 can be made of a suitable material to define a
plurality of axial grooves 72 and a radial orifice 74. The ungrooved portions of the lower
valve seat 71 contain the ball 70 within an axial path while the grooves 72 allow fluid to
be directed past the ball 70. The radial orifice 74 is in fluid communication with the
orifice 23 via an annular channel 75 formed in and/or between the lower valve seat 71
and the wall 76 of the valve body 38, In this embodiment, fluid pressure (PI) acting on
the ball 70 at control port 20B exceeds or overcomes the return force of the resilient
member 50 (see FIGS. 2 and 3). However, some amount of fluid leakage may be present
with respect to the ball 70.
[0031] Fluid 16 that bypasses the ball 70 is therefore directed through the axial
grooves 72, the radial orifice 74, and the annular channel 75, where it is ultimately vented
to the sump 12 via the orifice 23 to limit pressure acting on the armature 48. By venting
fluid 16 from the valve assembly 18 when the valve assembly 18, 118 is closed, accurate
measurement of pressure decay due to fluid leakage is enabled in a downstream fluid
circuit, such as the fluid circuit 13 of FIG. 1. The pressure transducer 11 shown in FIG. 1
can be used to perform the required pressure measurements. That is, absent such venting

using the orifice 23, measurement accuracy of fluid leakage past the armature 48 and the
upper valve seat 46 could be impaired depending upon the severity of the leak.
[0032] Referring to FIG. 5, when the valve assembly 118 is energized in a
normally-closed configuration, the ball 70 is no longer biased in the direction of arrow C
by the armature pin 48A. Fluid pressure (PI) can than move the ball 70 within the axial
grooves 72. The ball 70 should move only so far as to substantially block the radial
orifice 74, thus minimizing fluid flow into the orifice 23. In this manner, parasitic losses
are minimized when the valve assembly 118 is in an energized or open position as shown
in FIG. 5.
[0033] As will be understood by those of ordinary skill in the art, solenoid-
actuated valves such as the valve assemblies 18 and 118 described hereinabove can be
configured either as normally open or normally closed devices. A normally-open device
would fail, in the event of a power failure, in an open position, closing only when
energized. A normally closed device would do precisely the opposite, i.e., failing in a
closed position, requiring energizing current to actuate the device. While the valve
assembly 18 and 118 are each described hereinabove as being normally-closed devices,
either embodiment could be modified as normally open devices without departing from
the intended scope of the invention.
[0034] While the best modes for carrying out the invention have been described
in detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.

CLAIMS
1. A valve assembly (18) comprising:
a valve body (38) defining a supply port (20) in fluid communication with
a fluid supply (12), a first chamber (42), a second chamber (56) in fluid communication
with the first chamber (42), a first valve seat (46), and a control port (22) in fluid
communication with at least one fluid component (32);
an armature (48) positioned at least partially in the first chamber (42),
wherein the armature (48) is configured to seal against the first valve seat (46) when the
valve assembly (18) is closed, and to move away from the first valve seat (46) to allow
fluid (16) to pass to the control port (22) when the valve assembly (18) is open; and
a valve device (24) positioned in the second chamber (56), and having a
moveable portion (62, 70) positioned adjacent to the supply port (20) to selectively admit
fluid (16) into the second chamber (56) and past the first valve seat (46) when the valve
assembly (18) is open;
wherein the valve body (38) further defines at least one orifice (23)
between the supply port (20) and the first valve seat (46), the orifice (23) providing a
pressure unloading function for venting fluid (16) that leaks past the valve device (24)
when the valve assembly (18) is closed.
2. The valve assembly (18) of claim 1, further comprising a resilient
member (50) positioned to bias the armature (48) against the first valve seat (46) when
the valve assembly (18) is closed.
3. The valve assembly (18) of claim 1, wherein the moveable portion
(62, 70) is one of a ball (70) and a spool (62).
4. The valve assembly (18) of claim 3, wherein the moveable portion
(62, 70) is the ball (70), the valve assembly (18) further comprising a second valve seat

(71) within the second chamber (56), wherein the armature (48) includes an axial
extension (48A) having a free end that selectively moves the ball (70) into.contact with
the second valve seat (71) when the valve assembly (18) is closed.
5. The valve assembly (18) of claim 4, wherein the first valve seat
(46) is a fixed with respect to the valve body (38), and wherein the second valve seat (71)
is moveable with respect to the valve body (38).
6. The valve assembly (18) of claim 1, wherein the valve device (24)
is configured to substantially block the orifice (23) when the valve assembly (18) is open.
7. The valve assembly (18) of claim 5, wherein the valve device (24)
blocks at least approximately 75% of a diameter of the orifice (23) when the valve
assembly (18) is open.
8. A valve assembly (18) comprising:
a valve body (38) defining a first chamber (42), a second chamber (56), a
first valve seat (46) at least partially defining the first chamber (42), a supply port (20), a
control port (22), and at least one orifice (23);
a magnetic sleeve (15) disposed within the valve body (38);
an armature (48) adapted to move in conjunction with the magnetic sleeve
(15) and positioned substantially within the first chamber (42);
a solenoid coil (41) that can be energized to generate a magnetic field
sufficient for moving the magnetic sleeve (15) and armature (48) into one of an open and
a closed position;
a resilient member (50) that biases the armature (48) against the first valve
seat (46) when the valve assembly (18) is closed; and

a valve device (24) positioned within the second chamber (56) and biased
by the armature (48) to form a fluid seal with respect to the supply port (20) when the
valve assembly (18) is open;
wherein the magnetic sleeve (15) and the armature (48) move away from
the first valve seat (46) when the valve assembly (18) is open to allow the valve device
(24) to move away from the supply port (20), thus admitting fluid into the valve body
(38) and to the control port (20); and
wherein the magnetic sleeve (15) and the armature (48) move toward the
first valve seat (46) in the closed position to block fluid inlet into the valve body (38) and
allow a predetermined amount of fluid leakage past the valve device (24) to be vented
through the orifice (23) and out of the valve body (38).
9. The valve assembly (18) of claim 8, wherein the valve device (24)
includes one of a spool (62) and a ball (70).
10. The valve assembly (18) of claim 8, wherein the first valve seat
(46) defines a connecting port (33) between the first chamber (42) and the second
chamber (56), and wherein the armature (48) extends axially through the connecting port
(33).
11. A valve assembly (18) comprising:
a valve body (38) defining a supply port (20) and at least one orifice (23)
for selectively venting fluid (16) out of the valve body (38) when the valve assembly (18)
is closed;
a valve device (24) positioned within a first chamber (42) of the valve
body (38); and
a moveable armature (48) positioned at least partially within a second
chamber (56) of the valve body (38) that is downstream of the first chamber (42), the
moveable armature (48) being adapted for biasing the valve device (24) in a first

direction to minimize fluid inlet through the supply port (20) when the valve assembly
(18) is closed;
wherein one end of the orifice (23) is disposed within the first chamber
(42).
12. The valve assembly (18) of claim 12, wherein the valve device
(24) is one of a spool valve and a ball poppet.
13. The valve assembly (18) of claim 13, including the spool valve
(62), wherein the spool valve (62) is configured to substantially block the orifice (23)
when the valve assembly (18) is open.
14. The valve assembly (18) of claim 13, including the ball poppet and
a valve seat (71), wherein the valve seat (71) defines a plurality of axial grooves (72) for
retaining a ball portion (70) of the ball poppet in an axial path when the valve assembly
(18) is open.
15. The valve assembly (18) of claim 14, wherein the valve seat (71)
defines a radial channel (74) forming a fluid path between the axial grooves (72) and the
orifice (23) when the valve assembly (18) is closed.

A solenoid-actuated valve assembly (18) includes a valve body (38) defining a supply
port (20) in communication with a fluid supply (12), an upper or first chamber (42), a
lower or second chamber (56) in communication with the first chamber (42), a first valve
seat (46), and a control port (20) in fluid communication with a downstream fluid
component (23). An armature (48) seals against the first valve seat (46) when a solenoid
(36) is in a closed position, and a resilient member (50) otherwise biases the armature
(48) against the first valve seat (46). A lower valve device (24) is positioned in the
second chamber (56), and has a moveable portion (62, 70) that selectively admits fluid
(16) into the second chamber (56) in the open position. The valve body (38) defines at
least one orifice (23) between the supply port (20) and the first valve seat (46), the orifice
(23) providing a pressure unloading function for venting fluid (16) that leaks past the
valve device (24) when the solenoid (36) is not being actuated.