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Patent Abstract
A control valve system includes a housing having an inlet port,
a first output port, a second output port, and a valve chamber.
A primary spool and a secondary spool are independently slidable
in the valve chamber. The secondary spool has a first end for abutting
against the primary spool and has a second end with a working surface
area greater than the working surface areas at the ends of the primary
spool. A solenoid valve assembly controllably connects the inlet
port to the second end of the secondary spool. A biaser provides
a biasing force to the primary spool. A first fluid passage through
the primary spool provides fluid communication between the first
output port and a second end of the primary spool for displacing
the primary spool relative to the secondary spool in an energy saving
mode, thereby regulating a pressure at the first output relative
to the predetermined magnitude of the biasing force.
Patent Claims
What is claimed is:
1. A control valve system comprising: a housing having an inlet
port, a first output port, a second output port, and a valve chamber;
a primary spool having first and second longitudinal ends with respective
working surface areas being substantially equal, wherein said primary
spool is slidable in said valve chamber to a first position where
fluid communication is established between said inlet port and said
first output port, a second position where fluid communication is
established between said inlet port and said second output port,
and an intermediate third position where fluid communication is
generally prevented between said inlet port and both of said first
and second output ports; a secondary spool independently slidable
in said valve chamber, said secondary spool having a first end for
abutting against said second end of said primary spool and having
a second end with a working surface area greater than either of
said working surface areas of said primary spool; a solenoid valve
assembly coupled in fluid communication with said inlet port, wherein
said solenoid valve assembly is positionable in a first position
for providing fluid communication from said inlet port to said second
end of said secondary spool to move said primary spool from said
first position to said second position, and wherein said solenoid
valve assembly is positionable in a second position to isolate said
inlet port from said second end of said secondary spool; a biaser
providing a biasing force to said primary spool in a direction toward
said first position, said biasing force having a predetermined magnitude
when said primary spool is in said third position; and a first fluid
passage through said primary spool providing fluid communication
between said first output port and said second end of said primary
spool for displacing said primary spool relative to said secondary
spool in an energy saving mode when said solenoid valve is in said
second position, thereby regulating a pressure at said first output
relative to said predetermined magnitude of said biasing force.
2. The control valve system of claim 1 further comprising a second
fluid passage having an open condition and a closed condition for
selectably providing fluid communication between said inlet port
and said first end of said primary spool, wherein said control valve
system operates in a standard mode with said primary and secondary
spools moving in unison when said second fluid passage is in said
open condition, and where said control valve system operates in
said energy saving mode when said second fluid passage is in said
closed condition.
3. The control valve system of claim 2 further comprising an end
cap enclosing said valve chamber proximate said first end of said
primary spool, wherein said end cap includes a third passage therein,
and wherein said end cap is selectably attachable with a first orientation
wherein said third passage couples said second passage with said
valve chamber and with a second orientation wherein said second
passage is blocked from said valve chamber.
4. The control valve system of claim 2 further comprising a movable
obstruction for selectably blocking said second fluid passage to
create said open and closed conditions.
5. The control valve system of claim 4 wherein said movable obstruction
is comprised of a screw.
6. The control valve system of claim 1 wherein said valve chamber
comprises a main chamber receiving said primary spool and having
a first cross-sectional area corresponding to said working surface
areas of said first and second ends of said primary spool, and wherein
said valve chamber further comprises a secondary chamber receiving
at least a portion of said secondary spool and having a second cross-sectional
area corresponding to said working surface area of said working
surface area of said second end of said secondary spool.
7. The control valve system of claim 6 further comprising a relief
passage coupled to said secondary chamber for relieving pressure
in said secondary chamber when said solenoid valve is in said second
position.
8. The control valve of claim 1 wherein said second end of said
primary spool and said first end of said secondary spool include
complementary alignment features for intermeshing when said primary
spool and said secondary spool are abutting.
9. A method of operating a control valve system wherein said valve
system includes a housing having an inlet port, a first output port,
a second output port, and a valve chamber, wherein said valve system
includes a primary spool having first and second longitudinal ends
with respective working surface areas being substantially equal
and a secondary spool independently slidable in said valve chamber
and having a first end for abutting against said second end of said
primary spool and having a second end with a working surface area
greater than either of said working surface areas of said primary
spool, wherein said valve system includes a solenoid valve assembly
coupled in fluid communication with said inlet port, wherein said
valve system includes a biaser providing a biasing force to said
primary spool having a predetermined magnitude, wherein said valve
system includes a first fluid passage through said primary spool
providing fluid communication between said first output port and
said second end of said primary spool, said method comprising the
steps of: selecting either a standard mode or an energy saver mode
of said valve system by selectably connecting said inlet port to
said first end of said primary spool, wherein said standard mode
is comprised of said primary spool and said secondary spool moving
in unison within said valve chamber when said inlet port is in fluid
communication with said first end of said primary spool, and wherein
said energy saver mode is comprised of said primary spool and said
secondary spool moving independently within said valve chamber when
said inlet port is not in fluid communication with said first end
of said primary spool; energizing said solenoid to couple said inlet
port to said second end of said secondary spool, thereby providing
fluid communication from said inlet port to said second output port
in both said standard mode and said energy saver mode; and de-energizing
said solenoid to isolate said inlet port from said second end of
said secondary spool and from said second output port; whereby when
said solenoid is de-energized and said standard mode is selected,
then fluid communication is continuously maintained between said
inlet port and said first output port; and whereby when said solenoid
is de-energized and said energy save mode is selected, then fluid
communication is between said inlet port and said first output port
is modulated to maintain a predetermined pressure at said first
output port, said modulating of said fluid communication resulting
from moving said primary spool in said valve chamber independently
relative to said secondary spool.
10. The method of claim 9 wherein said step of selecting said standard
mode or said energy saver mode is comprised of positioning an end
cap on said housing in a first orientation or a second orientation,
wherein said end cap includes a passage for completing fluid communication
between said inlet port and said first end of said primary spool
when in said first orientation, and wherein said end cap includes
a solid body for blocking fluid communication between said inlet
port and said first end of said primary spool when in said second
orientation.
11. The method of claim 9 wherein said step of selecting said standard
mode or said energy saver mode is comprised of positioning a movable
obstruction relative to a blockable passage between said inlet port
and said first end of said primary spool.
12. The method of claim 11 wherein said movable obstruction is
a screw selectably movable into and out of said blockable passage
by rotation of said screw.
Patent Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/329,300 filed on Dec. 23, 2002, which is
a continuation-in-part of U.S. patent application Ser. No. 10/209,655
filed on Jul. 31, 2002, which claims the benefit of U.S. Provisional
Application No. 60/309,843, filed Aug. 3, 2001. The disclosures
of the above applications are incorporated herein by reference for
all purposes.
FIELD OF THE INVENTION
[0002] The present invention generally relates to control valves
and, more particularly, relates to a dual mode control valve wherein
one mode is capable of reducing the energy consumption thereof by
regulating a pressure at an output port.
BACKGROUND OF THE INVENTION
[0003] As is well known in the art, control valves have frequently
been used to control and supply a working fluid, such as air, to
a working device. Typically, these control valves employ a moveable
valve spool disposed in a valve housing. The valve housing includes
a plurality of fluid passages that are selectively interconnected
in response to movement of the valve spool so as to control the
flow of the fluid and, thus, the output of the control valve.
[0004] Conventional control valves often employ a solenoid valve
mounted thereto for actuating the valve spool. The solenoid valve
is controlled via an electrical input signal between a first position,
where the solenoid valve is de-energized so as to close a fluid
passage between an input pilot pressure and an output controlling
pressure and to open the outlet to atmosphere, and a second position,
where the solenoid is energized via the electrical input so as to
open a passageway between the input pilot pressure and the output
controlling pressure and block the fluid passage from outlet to
exhaust.
[0005] It should be readily appreciated to one skilled in the art
that in order to apply a constant controlling pressure, the electrical
control signal must continue to energize the solenoid valve. That
is, in order for a conventional control valve to maintain the spool
in a predetermined position, it is necessary to maintain a constant
control pressure upon one side of the spool. Therefore, in order
to maintain this constant control pressure on the spool, it is necessary
to maintain the solenoid valve in an opened and, thus, energized
state. Moreover, it is necessary to employ full line fluid pressure
to displace and maintain the working device in a predetermined position.
Therefore, it will be understood that operating a device at full
line pressure requires more energy to drive compressors than operating
the device at a reduced line pressure.
[0006] Accordingly, there exists a need in the relevant art to
provide a control valve capable of producing an output of working
fluid to be used with a conventional working device that is capable
of minimizing the energy consumed during actuation. Furthermore,
there exists a need in the relevant art to provide a control valve
that maintains the position of a control element at a pressure less
than full line pressure. In certain valve applications, however,
it may still be desirable to operate a valve in the standard mode
wherein full line pressure is consumed at all times. Thus, there
exists a need in the relevant art to provide valves capable of either
an energy saver mode or a standard mode while minimizing manufacturing
and inventory stocking costs associated with multiple valve types.
SUMMARY OF THE INVENTION
[0007] A control valve system having an advantageous construction
is provided. The control valve system includes a housing having
an inlet port, a first output port, a second output port, and a
valve chamber. A primary spool has first and second longitudinal
ends with respective working surface areas being substantially equal,
wherein the primary spool is slidable in the valve chamber to a
first position where fluid communication is established between
the inlet port and the first output port, a second position where
fluid communication is established between the inlet port and the
second output port, and an intermediate third position where fluid
communication is generally prevented between the inlet port and
both of the first and second output ports. A secondary spool is
independently slidable in the valve chamber and has a first end
for abutting against the second end of the primary spool and has
a second end with a working surface area greater than the other
working surface areas. A solenoid valve assembly is positionable
in a first position for providing fluid communication from the inlet
port to the second end of the secondary spool to move the primary
spool from the first position to the second position, and in a second
position to isolate the inlet port from the second end of the secondary
spool. A biaser provides a biasing force to the primary spool in
a direction toward the first position which has a predetermined
magnitude when the primary spool is in the third position. A first
fluid passage through the primary spool provides fluid communication
between the first output port and the second end of the primary
spool for displacing the primary spool relative to the secondary
spool in an energy saving mode when the solenoid valve is in the
second position, thereby regulating a pressure at the first output
relative to the predetermined magnitude of the biasing force.
[0008] Further areas of applicability of the present invention
will become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description and specific
examples, while indicating the preferred embodiment of the invention,
are intended for purposes of illustration only and are not intended
to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will become more fully understood
from the detailed description and the accompanying drawings, wherein:
[0010] FIG. 1 is a cross-sectional view of a control valve system
according to a first embodiment of the present invention illustrated
in a normal operation mode where the solenoid valve assembly is
energized;
[0011] FIG. 2 is a cross-sectional view illustrating the control
valve system of FIG. 1 wherein the solenoid valve assembly is de-energized;
[0012] FIG. 3 is a cross-sectional view illustrating the control
valve system of FIG. 1 being maintained in a predetermined position
while the solenoid valve assembly remains de-energized and the valve
spool is in an equilibrium position;
[0013] FIG. 4 is a circuit diagram illustrating the control valve
system according to the first embodiment of the present invention;
[0014] FIG. 5 is a cross-sectional view of a control valve system
according to a second embodiment of the present invention illustrated
in an initial position where the first and second solenoid valve
assemblies are de-energized and the piston is stationary;
[0015] FIG. 6 is a cross-sectional view illustrating the control
valve system of FIG. 5 wherein the first solenoid valve assembly
is energized and the second solenoid valve assembly is de-energized;
[0016] FIG. 7 is a cross-sectional view illustrating the control
valve system of FIG. 5 wherein the first and second solenoid valve
assemblies are de-energized and the piston continues to extend;
[0017] FIG. 8 is a cross-sectional view illustrating the control
valve system of FIG. 5 wherein the first solenoid valve assembly
is de-energized and the second solenoid valve assembly is energized;
[0018] FIG. 9 is a cross-sectional view illustrating the control
valve system of FIG. 5 wherein the first and second solenoid valve
assemblies are de-energized and the piston continues to retract;
[0019] FIG. 10 is a cross-sectional view illustrating the control
valve system of FIG. 5 wherein the first and second solenoid valve
assemblies are de-energized and the piston is stationary;
[0020] FIG. 11 is a circuit diagram illustrating the control valve
system according to the second embodiment of the present invention;
[0021] FIG. 12 is a circuit diagram of a control valve system according
to a third embodiment of the present invention illustrated in an
initial position where the solenoid valve assembly is de-energized
and the piston is stationary;
[0022] FIG. 13 is a schematic diagram illustrating the feedback
passage being disposed externally from the housing;
[0023] FIG. 14 is a schematic diagram illustrating the feedback
passage being disposed internally in the housing;
[0024] FIG. 15 is a cross-sectional view of a control valve system
according to a fourth embodiment of the present invention illustrated
in a normal operation mode where the solenoid valve assembly is
energized;
[0025] FIG. 16 is a cross-sectional view illustrating the control
valve system of FIG. 15 wherein the solenoid valve assembly is de-energized;
[0026] FIG. 17 is a cross-sectional view illustrating the control
valve system of FIG. 15 being maintained in a predetermined position
while the solenoid valve assembly remains de-energized and the valve
spool is in an equilibrium position;
[0027] FIG. 18 is a cross-sectional view of the control valve system
of FIG. 15, having an end cap reversed, in a normal operation mode
where the solenoid valve assembly is energized;
[0028] FIG. 19 is a cross-sectional view of the control valve system
of FIG. 15, having the end cap reversed, where the solenoid valve
assembly is de-energized;
[0029] FIG. 20 is a cross-sectional view of a variation of the
control valve system of FIG. 15 illustrated in a normal operation
mode where the solenoid valve assembly is energized;
[0030] FIG. 21 is a cross-sectional view illustrating the control
valve system of FIG. 20 wherein the solenoid valve assembly is de-energized;
[0031] FIG. 22 is a cross-sectional view illustrating the control
valve system of FIG. 20 being maintained in a predetermined position
while the solenoid valve assembly remains de-energized and the valve
spool is in an equilibrium position;
[0032] FIG. 23 is a cross-sectional view of a control valve system
of a fifth embodiment, wherein the valve is configured in a standard
mode and the solenoid valve system is energized;
[0033] FIG. 24 is a cross-sectional view illustrating the control
valve system of FIG. 23 wherein the solenoid valve assembly is de-energized;
[0034] FIG. 25 is a cross-sectional view illustrating the control
valve system of FIG. 23 wherein the valve is configured in an energy
saver mode and the solenoid valve assembly is energized;
[0035] FIG. 26 is a cross-sectional view illustrating the control
valve system of FIG. 25 wherein the solenoid valve assembly is de-energized;
[0036] FIG. 27 is a cross-sectional view illustrating the control
valve system of FIG. 25 wherein the solenoid valve assembly is de-energized
and the pressure to the first output port is being regulated in
the energy saver mode;
[0037] FIG. 28 is a cross-sectional view of the control valve system
of FIGS. 23-27 including flat surfaces between the primary and secondary
spools; and
[0038] FIG. 29 is a cross-sectional view illustrating a screw for
selectably obstructing the passage for placing the control valve
system into either the standard mode or the energy saver mode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] The following description of the preferred embodiments is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses. For example, the principles
of the present invention are equally applicable to a wide variety
of valve systems, such as spool valves, poppet valves (i.e. resilient,
metal, ceramic, and the like), trapping presses, and feedback controls.
[0040] Referring now to FIGS. 1-4 in which like reference numerals
designate like or corresponding parts throughout the several views,
there is illustrated a control valve system, which is designated
generally by the reference numeral 10. Control valve system 10 is
shown as a fluid control valve in FIGS. 1-3 and as a fluid circuit
in FIG. 4.
[0041] Referring in particular to FIGS. 1-3, control valve system
10 comprises a main valve assembly 12 and a solenoid valve assembly
14. Main valve assembly 12 is positioned adjacent to and operably
coupled to solenoid valve assembly 14. Main valve assembly 12 includes
a fluid inlet passage 16, a first exhaust passage 18, a second exhaust
passage 20, and a valve bore 22. Disposed within valve bore 22 is
a valve member or spool 24. Spool 24 is normally biased via a spring
26 into a seated position where a face portion 28 of spool 24 contacts
a first stop 30 disposed in valve bore 22 to exhaust fluid from
a backside chamber 32 of a piston member assembly 34 out second
exhaust passage 20. As will be described below, spool 24 is further
positionable in an unseated position where face portion 28 of spool
24 is spaced apart from first stop 30 of valve bore 22, yet a shoulder
portion 36 disposed on an opposing side of spool 24 contacts a second
stop 38 disposed in valve bore 22 to exhaust fluid from a front
side chamber 40 of piston member assembly 34 through first exhaust
passage 18.
[0042] It should be appreciated that spring 26 may be eliminated.
In this case, spool 24 would be actuated in response to differential
fluid pressure exerted upon opposing faces of spool 24. It is also
anticipated that these faces could include differently sized surfaces
areas (i.e. different area ratios), which would enable control valve
system 10 to be easily modified to produce a wide range of different
output pressures.
[0043] Control valve system 10 further includes a plurality of
fluid passages interconnecting fluid inlet passage 16, first exhaust
passage 18, and second exhaust passage 20. A fluid passage 42 extends
between fluid inlet passage 16 and an inlet to solenoid valve assembly
14. Fluid passage 42 serves as a pilot passage to supply a pilot
pressure to solenoid valve assembly 14. A fluid passage 44 extends
between an outlet of solenoid valve assembly 14 and a shuttle valve
46.
[0044] Shuttle valve 46 generally includes a shuttle ball 48 moveably
disposed in a shuttle chamber 50. As will be described below, shuttle
valve 46 moves in response to fluid pressure to fluidly block opposing
ends of shuttle valve 46 against fluid flow. Shuttle valve 46 is
fluidly coupled to a valve chamber 52 via a fluid passage 54. Valve
chamber 52 is adjacent face portion 28 of spool 24 and disposed
within valve bore 22 such that fluid pressure within valve chamber
52 acts upon face portion 28 to move spool 24 against the biasing
force of spring 26.
[0045] However, as seen in FIGS. 12-14, shuttle ball 48 may be
eliminated to provide a more simplified design. Specifically, a
fluid passage 100 extends between front side chamber 40 and solenoid
58. Fluid passage 100 permits the flow or exhaust of pilot fluid
from valve chamber 52 to front side chamber 40 when solenoid 58
is in the position shown in FIG. 12. However, it should be appreciated
that fluid passage 100 may extend either externally (see FIG. 13)
or internally (FIG. 14) of main valve assembly 12.
[0046] Control valve system 10 further includes a feedback passage
56 extending between shuttle valve 46 and first exhaust passage
18. Accordingly, shuttle ball 48 of shuttle valve 46 is moveable
within shuttle chamber 50 into a first position, where shuttle ball
48 prevents fluid flow through feedback passage 56, and a second
position, where shuttle ball 48 prevents back flow of fluid through
fluid passage 44.
[0047] FIG. 1 illustrates control valve system 10 in a normal operation
mode in which pressurized fluid from fluid inlet passage 16 is directed
into backside chamber 32 of piston member assembly 34 to drive a
piston 62 outward (to the right in the figures). Specifically, pressurized
fluid from fluid inlet passage 16 is provided in fluid passage 42.
Referring to FIG. 4, energizing solenoid valve assembly 14 will
establish a fluid communication between fluid passage 42 and fluid
passage 44. That is, a solenoid 58 of solenoid valve assembly 14
is energized such that a solenoid spool 59 is moved to the right
in FIG. 4 against the biasing force of a solenoid spring 60. Pressurized
fluid is then introduced from fluid passage 44 into shuttle valve
46, thereby moving shuttle ball 48 against feedback passage 56.
Pressurized fluid within shuttle valve 46 is then directed into
valve chamber 52. The fluid pressure within valve chamber 52 acts
upon face portion 28 of spool 24. Once the fluid pressure within
valve chamber 52 is greater than the biasing force of spring 26,
spool 24 moves to the right until shoulder portion 36 of spool 24
is seated upon second stop 38. This movement of spool 24 enables
fluid to flow from fluid inlet passage 16 into backside chamber
32 of piston member assembly 34, thereby extending piston 62 outward
(to the right in FIGS. 1-4). Accordingly, when control valve system
10 is in the position illustrated in FIG. 1, fluid inlet passage
16, backside chamber 32 of piston member assembly 34, fluid passage
42, shuttle valve 46, and valve chamber 52 are all at the same fluid
pressure, namely equal to the fluid pressure of fluid inlet passage
16.
[0048] Referring now to FIG. 2, solenoid valve assembly 14 is de-energized
and therefore pilot fluid from fluid passage 42 is prevented from
entering shuttle valve 46 and, consequently, valve chamber 52. Therefore,
the biasing force of spring 26 acting on shoulder portion 36 of
spool 24 biases spool 24 leftward until face portion 28 generally
contacts first stop 30. This leftward movement of spool 24 enables
fluid communication between fluid inlet passage 16 and front side
chamber 40 of piston member assembly 34, thereby retracting piston
62.
[0049] As can be appreciated from FIG. 2, feedback passage 56 is
in fluid communication with front side chamber 40 of piston member
assembly 34 and, therefore, is at the same fluid pressure. The introduction
of pressurized fluid from fluid inlet passage 16 into front side
chamber 40 and feedback passage 56 forces shuttle ball 48 of shuttle
valve 46 leftward, since the fluid pressure of fluid inlet passage
16 is now greater than the fluid pressure within valve chamber 52.
This leftward movement of shuttle ball 48 and shuttle valve 46 then
permits fluid flow from front side chamber 40 of piston member assembly
34 into valve chamber 52, thereby increasing the fluid pressure
within valve chamber 52 once again. During this time, fluid is exhausted
from backside chamber 32 of piston member assembly 34 through second
exhaust passage 20.
[0050] As best seen in FIG. 3, fluid flow from fluid inlet passage
16 into front side chamber 40 of piston member assembly 34 and valve
chamber 52 will continue until the pressure within valve chamber
52 is equal to the biasing force of spring 26. When the fluid pressure
within valve chamber 52 equals the biasing force of spring 26, spool
24 reaches an intermediate equilibrium position wherein fluid flow
from fluid inlet passage 16 into any of the remaining fluid passages
is prevented. However, it should be appreciated by one skilled in
the art that any fluid leaks or other anomalies which decrease the
fluid pressure in front side chamber 40 of piston member assembly
34 will cause a simultaneous decrease in fluid pressure within valve
chamber 52. This decrease in fluid pressure in valve chamber 52
enables spring 26 to move spool 24 leftward, thereby again opening
fluid communication between fluid inlet passage 16 and front side
chamber 40 of piston member assembly 34. As explained above, this
fluid communication will continue until the fluid pressure within
front side chamber 40, feedback passage 56, and valve chamber 52
is equal to the biasing force of spring 26. Therefore, it should
be clear that feedback passage 56 serves to provide a method of
automatically maintaining a fluid pressure in front side chamber
40 of piston member assembly 34 simply by choosing an appropriate
biasing force in spring 26. The preferred fluid pressure to be maintained
is directly proportional to the force of spring 26 and, therefore,
spring 26 may be selected to determine the equilibrium fluid pressure.
[0051] Moreover, it should be appreciated that the pressure regulation
feature of the present invention is accomplished without the need
to provide full line pressure, which would otherwise consume an
excessive amount of electrical energy. That is, by way of non-limiting
example, traditional double action cylinders often operate such
that their return to their initial position is only accomplished
through the use of full-line pressure. This use of full-line pressure
in the return stroke consumes an equivalent amount of compressed
air as that consumed during a power stroke. This consumption of
compressed air during the return stroke is believed to be unnecessary.
According to the principles of the present invention, the low pressure
in one outlet is sufficient for a rapid return stroke, which reduces
the amount of compressed air that is consumed, thereby reducing
the energy consumed by the work element. Additionally, due to the
low pressure that is applied, the potential for leaks in the cylinder
and/or fittings is also reduced. These advantages are obtained through
the operation of the spool as a pressure regulator.
[0052] Referring now to FIGS. 5-11, in which like reference numerals
designate like or corresponding parts throughout the several views
and those views of the first embodiment, there is illustrated a
control valve system 10' in accordance with a second embodiment
of the present invention. Control valve system 10' is illustrated
as a fluid control valve in FIGS. 5-10 and as a schematic fluid
circuit in FIG. 11.
[0053] Referring now to FIG. 5, control valve system 10' comprises
a second solenoid valve assembly 70 that is mounted to a main valve
assembly 12'. Main valve assembly 12' is positioned adjacent to
and operably coupled to first solenoid valve assembly 14 and second
solenoid valve assembly 70. Main valve assembly 12' includes fluid
inlet passage 16, first exhaust passage 18, second exhaust passage
20, and valve bore 22. Disposed within valve bore 22 is spool 24.
Spool 24 is normally biased via spring 26 into a seated position
where face portion 28 of spool 24 contacts first stop 30 disposed
in valve bore 22 to exhaust fluid from backside chamber 32 of piston
member assembly 34 out second exhaust passage 20. As described above,
spool 24 is positionable in an unseated position where face portion
28 of spool 24 is spaced apart from first stop 30 of valve bore
22, yet shoulder portion 36 contacts second stop 38 disposed in
valve bore 22 to exhaust fluid from front side chamber 40 of piston
member assembly 34 through first exhaust passage 18.
[0054] Control valve system 10' further includes a plurality of
fluid passages interconnecting fluid inlet passage 16, first exhaust
passage 18, and second exhaust passage 20. Fluid passage 42 extends
between fluid inlet passage 16 and the inlet to solenoid valve assembly
14. Fluid passage 42 serves as a pilot passage to supply pilot pressure
to solenoid valve assembly 14. Fluid passage 44 extends between
the outlet of solenoid valve assembly 14 and shuttle valve 46. Shuttle
valve 46 generally includes shuttle ball 48 moveably disposed in
a shuttle chamber 50. Shuttle valve 46 moves in response to fluid
pressure to fluidly block opposing ends of shuttle valve 46 against
fluid flow. Shuttle valve 46 is fluidly coupled to valve chamber
52 via fluid passage 54. Valve chamber 52 is adjacent face portion
28 of spool 24 and disposed within valve bore 22 such that fluid
pressure within valve chamber 52 acts upon face portion 28 to move
spool 24 against the biasing force of spring 26.
[0055] Control valve system 10' further includes a first feedback
passage 72 extending between backside chamber 32 of piston member
assembly 34 and an inlet of second solenoid valve assembly 70. A
restrictor 74 is disposed within fluid passage 70 to limit the amount
of fluid flow through first feedback passage 72. A fluid passage
76 extends between second solenoid valve assembly 70 and a second
shuttle valve 78. Fluid passage 76 is further in fluid communication
with first feedback passage 72 downstream of restrictor 74.
[0056] Second shuttle valve 78 generally includes a shuttle ball
80 moveably disposed within a shuttle chamber 82. As will be described
below, second shuttle valve 78 moves in response to fluid pressure
to fluidly block opposing ends of second shuttle valve 78 against
fluid flow. Second shuttle valve 78 is fluidly coupled to front
side chamber 40 of piston member assembly 34 via a fluid passage
84. Furthermore, a second feedback passage 86 extends between second
shuttle valve 78 and first shuttle valve 46. Accordingly, shuttle
ball 48 of first shuttle valve 46 is moveable within shuttle chamber
50 into a first position, where shuttle ball 48 prevents fluid flow
from first shuttle valve 46 to second shuttle valve 78 and permits
fluid flow into valve chamber 52, and a second position, where shuttle
ball 48 prevents back flow of fluid through fluid passage 44 and
permits fluid flow from second feedback passage 86 to valve chamber
52. Furthermore, shuttle ball 80 of second shuttle valve 78 is moveable
within shuttle chamber 82 into a first position, where shuttle ball
80 prevents fluid flow from fluid passage 76 to fluid passage 84,
and a second position, where shuttle ball 80 prevents back flow
of fluid from second feedback passage 86 to fluid passage 76. It
should be noted, however, that shuttle ball 80 of second shuttle
valve 78 can not block second feedback passage 86, hence second
feedback passage 86 is always in fluid communication with either
fluid passage 76 or fluid passage 84.
[0057] FIG. 5 illustrates control valve system 10' in its initial
equilibrium position. As illustrated in FIG. 6, first solenoid valve
assembly 14 is then energized.
[0058] FIG. 6 illustrates control valve system 10' in a normal
operation mode in which pressurized fluid from fluid inlet passage
16 is directed into backside chamber 32 of piston member assembly
34 to drive piston 62 outward (to the right in the FIGS.). Specifically,
pressurized fluid from fluid inlet passage 16 is provided in fluid
passage 42. First solenoid valve assembly 14 is energized such that
fluid communication is established between fluid passage 42 and
fluid passage 44. Pressurized fluid is then introduced from fluid
passage 44 into first shuttle valve 46, thereby moving shuttle ball
48 against second feedback passage 86. Pressurized fluid within
first shuttle valve 46 is then directed into valve chamber 52. The
fluid pressure within valve chamber 52 acts upon face portion 28
of spool 24. Once the fluid pressure within valve chamber 52 is
greater than the biasing force of spring 26, spool 24 moves to the
right until shoulder portion 36 of spool 24 is seated upon second
stop 38. This movement of spool 24 enables fluid to flow from fluid
inlet passage 16 into backside chamber 32 of piston member assembly
34, thereby extending piston 62 outward (to the right in FIGS. 5-11).
Fluid flow is consequently established between backside chamber
32 and first feedback passage 72, second solenoid valve assembly
70, and second shuttle valve 78. Due to the pressure difference
in second shuttle valve 78, shuttle ball 80 will shift to close
fluid passage 84 and to open second feedback passage 86. Accordingly,
when control valve system 10 is in the position illustrated in FIG.
6, fluid inlet passage 16, backside chamber 32 of piston member
assembly 34, fluid passage 42, first shuttle valve 46, and valve
chamber 52 are all at the same fluid pressure, namely equal to the
fluid pressure of fluid inlet passage 16.
[0059] Referring now to FIG. 7, first solenoid valve assembly 14
and second solenoid valve assembly 70 are de-energized and therefore
pilot fluid from fluid passage 42 is prevented from entering first
shuttle valve 46 and, consequently, valve chamber 52. Therefore,
the biasing force of spring 26 acting on shoulder portion 36 of
spool 24 biases spool 24 leftward until face portion 28 generally
contacts first stop 30. This leftward movement of spool 24 enables
fluid communication between fluid inlet passage 16 and front side
chamber 40 of piston member assembly 34, thereby retracting piston
62.
[0060] As best seen in FIG. 8, when second solenoid valve assembly
70 is energized such that fluid communication is established between
fluid passage 76 and an exhaust passage 88. Consequently, fluid
pressure is relieved from valve chamber 52, first shuttle valve
46, second feedback passage 86, second shuttle valve 78, and at
least a portion of first feedback passage 72 downstream of restrictor
74. This reduction of fluid pressure in valve chamber 52 causes
spool 24 to move to the left under the biasing force of spring 26
as illustrated in FIG. 9. Therefore, fluid flow is established between
fluid inlet passage 16 and front side chamber 40 of piston chamber
assembly 32 to retract piston 62.
[0061] As can be appreciated from FIG. 10, fluid passage 84, second
shuttle valve 78, second feedback passage 86, and first shuttle
valve 46 establish fluid communication between front side chamber
40 of piston member assembly 34 and valve chamber 52 and, therefore,
are at the same fluid pressure in this state. As in the first embodiment,
these passages serve to maintain the fluid pressure within front
side chamber 40 at a pressure directly proportional to spring 26
and are able to overcome pressure leakage and the like using a pressure
less than full line pressure, thereby reducing the amount of energy
consumed.
[0062] Referring now to FIGS. 15-19, in which like reference numerals
designate like or corresponding parts throughout the several views
and those views of the previous embodiments, there is illustrated
a control valve system 10" in accordance with a fourth embodiment
of the present invention.
[0063] Referring in particular to FIGS. 15-17, control valve system
10" comprises a main valve assembly 12" and a solenoid
valve assembly 14. Main valve assembly 12" is positioned adjacent
to and operably coupled to solenoid valve assembly 14. Main valve
assembly 12" includes a fluid inlet passage 16, a first exhaust
passage 18, a second exhaust passage 20, and a valve bore 22".
Disposed within valve bore 22" is a valve member or spool 24".
Spool 24" is normally biased via a spring 26 and fluid pressure
acting upon an end face 36" into a far left position to exhaust
fluid from a backside chamber 32 (as in FIGS. 1-14) of a piston
member assembly 34 out second exhaust passage 20 (FIG. 16). As will
be described below, spool 24" is further positionable in a
far-right position to exhaust fluid from a front side chamber 40
of piston member assembly 34 through first exhaust passage 18 (FIG.
15).
[0064] Spool 24" of control valve system 10" further
includes an enlarged face portion 28" mounted to or formed
integrally with spool 24". Enlarged end face 28" is disposed
within an enlarged valve bore section 200 of valve bore 22".
Enlarged face portion 28" includes a seal 202 disposed between
enlarged face portion 28" and the sidewalls of enlarged valve
bore section 200 to provide a sealing engagement between a first
chamber 204 of enlarged valve bore section 200 (FIG. 15) and a second
chamber 206 of enlarged valve bore section 200 (FIG. 16). Second
chamber 206 is ventable through a vent 207. As can be seen from
the figures, enlarged face portion 28" is larger in diameter
than spool 24". This arrangement enables a lesser amount of
pilot pressure from solenoid valve assembly 14 to actuate spool
24" to overcome the biasing force of spring 26 and the fluid
pressure acting against end face 36" as compared to the above-recited
embodiments. However, it should be understood that enlarged face
portion 28" may be of any size that is conducive to the particular
application, within the physical limits of control valve system
10".
[0065] Control valve system 10" further includes a piston
208 moveably disposed within a piston bore 210. Piston 208 includes
a seal 212 disposed between piston 208 and piston bore 210 to provide
a sealing engagement between a first chamber 214 of piston bore
210 (FIG. 15) and a second chamber 216 of piston bore 210 (FIG.
17). A stem 218 extends orthogonally from piston 208 into enlarged
valve bore section 200 through an aperture 219. Stem 218 is sized
to selectively engage enlarged face portion 28" of spool 24",
as will bedescribed below. Piston 208 is preferably larger in diameter
than spool 24". Aperture 219 may be sized to permit first chamber
214 and first chamber 204 to be in fluid communication with each
other.
[0066] Control valve system 10" still further includes a plurality
of fluid passages operably interconnecting fluid inlet passage 16,
first exhaust passage 18, second exhaust passage 20, spool 24",
and piston 208. A fluid passage 42" extends between fluid inlet
passage 16 and an inlet to solenoid valve assembly 14. Fluid passage
42" serves as a pilot passage to supply a pilot pressure to
solenoid valve assembly 14. Fluid passage 42" further extends
in an opposite direction to a fluid chamber 220 defined by spool
24", end face 36" of valve bore 22", and an end cap
222. A fluid passage 44" extends between an outlet of solenoid
valve assembly 14 and first chamber 204 of enlarged valve bore section
200.
[0067] Control valve system 10" further includes a feedback
passage 224 extending between front side chamber 40 and second chamber
216 of piston bore 210. Accordingly, feedback passage 224 serves
to provide fluid pressure from front side chamber 40 to act against
piston 208 to drive piston 208 to the right. As can be seen from
FIGS. 15-19, feedback passage 224 extends through an end cap 226.
The significance of this arrangement will be discussed below.
[0068] FIG. 15 illustrates control valve system 10" in a normal
operation mode in which pressurized fluid from fluid inlet passage
16 is directed into backside chamber 32 of piston member assembly
34 to drive a piston 62 outward (to the right in the figures). Specifically,
pressurized fluid from fluid inlet passage 16 is provided in fluid
passage 42". As seen in FIG. 15, solenoid valve assembly 14
is energized such that fluid communication is established between
fluid passage 42" and fluid passage 44". Pressurized fluid
is then introduced from fluid passage 44" into first chamber
204 of enlarged valve bore section 200. The fluid pressure within
first chamber 204 of enlarged valve bore section 200 acts upon enlarged
face portion 28" of spool 24". Simultaneously, pressurized
fluid is introduced from fluid passage 42" into fluid chamber
220 and acts upon end face 36" of spool 24". Once the
force exerted upon enlarged face portion 28" from the fluid
pressure within first chamber 204 of enlarged valve bore section
200 is greater than the sum of the biasing force of spring 26 and
the force exerted upon end face 36" of spool 24", spool
24" moves to the right until enlarged face portion 28"
engages a shoulder portion 228. This movement of spool 24"
enables fluid to flow from fluid inlet passage 16 into backside
chamber 32 of piston member assembly 34, thereby extending piston
62 outward (to the right in FIGS. 1-4). Accordingly, when control
valve system 10" is in the position illustrated in FIG. 15,
fluid inlet passage 16, backside chamber 32 of piston member assembly
34, fluid passage 42", fluid chamber 220, and first chamber
204 of enlarged valve bore section 200 are all at the same fluid
pressure, namely equal to the fluid pressure of fluid inlet passage
16.
[0069] Referring now to FIG. 16, solenoid valve assembly 14 is
de-energized and therefore pilot fluid from fluid passage 42"
is prevented from entering first chamber 204 of enlarged valve bore
section 200. Hence, first chamber 204, second chamber 206, and first
chamber 214 are vented to atmosphere. Thus, the sum of the biasing
force of spring 26 and the force of fluid pressure in chamber 220
acting upon end face 36" of spool 24" biases spool 24"
leftward until enlarged face portion 28" generally contacts
stem 218. This leftward movement of spool 24" enables fluid
communication between fluid inlet passage 16 and front side chamber
40 of piston member assembly 34, thereby retracting piston 62.
[0070] As can be appreciated from FIG. 16, feedback passage 224
is in fluid communication with front side chamber 40 of piston member
assembly 34 and, therefore, is at the same fluid pressure as fluid
inlet passage 16. The introduction of pressurized fluid from fluid
inlet passage 16 into front side chamber 40 and feedback passage
224 enters second chamber 216 of piston bore 210 and forces piston
208 rightward. Due to the physical contact between stem 218 and
enlarged face portion 28" of spool 24", any rightward
movement of piston 208 causes a corresponding rightward movement
of spool 24".
[0071] The pressure at which this rightward movement of spool 24"
occurs is dependent upon the relative surface areas of piston 208
and end face 36" of spool 24" in addition to the biasing
force of spring 26. In other words, spool 24" will move rightward
once the fluid force exerted on piston 208 is greater than the sum
of the fluid force, the biasing force, and any frictional force
exerted on the right side. Therefore, in order to determine the
applicable forces, it is necessary to consider the 1) fluid pressure
and the 2) surface area the fluid pressure acts upon. As seen in
FIG. 16, the fluid pressure acting upon piston 208 and spool 24"
is equal to each other (namely, equal to the fluid pressure of fluid
inlet passage 16). Therefore, because the surface area of piston
208 is greater than the surface area of end face 36" of spool
24", a greater force is produced on the left side of spool
24" that overcome the biasing force of spring 26 causing spool
24" to move rightward.
[0072] As seen in FIG. 17, spool 24" will continue to move
rightward until spool 24" blocks fluid inlet passage 16, at
which time spool 24" reaches an equilibrium position. This
equilibrium position is characterized in that a predetermined fluid
pressure less than the inlet pressure of fluid inlet passage 16
but greater than atmosphere exists in front side chamber 40 and,
due to feedback passage 224, second chamber 216 of piston bore 210.
This force exerted on piston 208 is in equilibrium with the sum
of the force exerted on end face 36" and the force of spring
26. However, it should be appreciated by one skilled in the art
that any fluid leaks or other anomalies, which decreases this balance,
will cause a simultaneous decrease in fluid pressure within second
chamber 216 of piston bore 210. This decrease in fluid pressure
in second chamber 216 of piston bore 210 enables the pressure acting
on end face 36" of spool 24" and the biasing force of
spring 26 to move spool 24" leftward, thereby again opening
fluid communication between fluid inlet passage 16 and front side
chamber 40 of piston member assembly 34 until an equilibrium is
once again achieved. Therefore, it should be clear that this arrangement
serves to provide a low energy consuming method of automatically
maintaining a predetermined fluid pressure in front side chamber
40 of piston member assembly 34 simply by choosing the appropriate
relative areas of piston 208 and end face 36" and choosing
the appropriate biasing force in spring 26, thereby eliminating
the need for a shuttle valve 46.
[0073] Referring now to FIGS. 18 and 19, it can be seen that the
present embodiment provides the opportunity to bypass piston 208
completely, thereby providing a control valve capable of operating
in a non-energy saving mode. As is well known to those skilled in
the art, it is sometimes preferred to use an energy saving control
valve in one application while using a non-energy saving control
valve in another application. Because the cost to stock both versions
of replacement control valves can be enormous, control valve system
10" provides the opportunity to use one control valve in either
application--energy saving mode or non-energy saving mode. To achieve
this result, control valve system 10" is equipped with removable
end cap 226. Feedback passage 224 extends through end cap 226. Accordingly,
if an energy saving mode is needed, end cap 226 is positioned as
is shown in FIGS. 15-17 (where fluid communication is maintained
between front side chamber 40 and second chamber 216 of piston bore
210). However, on the other hand, if a non-energy saving mode is
needed, end cap 226 is reversed as is shown in FIGS. 18-19 (wherein
fluid communication is interrupted between front side chamber 40
and second chamber 216 of piston bore 210). In this position, control
valve system 10" can operate similar to a standard two-position,
four-way control valve.
[0074] Moreover, it should be appreciated that the pressure regulation
feature of the present invention is accomplished without the need
to provide full line pressure, which would otherwise consume an
excessive amount of electrical energy. That is, by way of non-limiting
example, traditional double action cylinders often operate such
that their return to their initial position is only accomplished
through the use of full-line pressure. This use of full-line pressure
in the return stroke consumes an equivalent amount of compressed
air as that consumed during a power stroke. This consumption of
compressed air during the return stroke is believed to be unnecessary.
According to the principles of the present invention, the low pressure
in one outlet is sufficient for a rapid return stroke, which reduces
the amount of compressed air that is consumed, thereby reducing
the energy consumed by the work element. Additionally, due to the
low pressure that is applied, the potential for leaks in the cylinder
and/or fittings is also reduced. These advantages are obtained through
the operation of the spool as a pressure regulator.
[0075] With reference to FIGS. 20-22, a variation of the above
principles described in connection with the fourth embodiment is
illustrated. In this regard, a control valve system 10'" is
illustrated having a spool 24'" with an enlarged face portion
28'" mounted to or formed integrally with spool 24'".
Enlarged end face 28'" is disposed within an enlarged valve
bore section 200' of valve bore 22'". Enlarged face portion
28'" includes a pair of seals 202' disposed between enlarged
face portion 28'" and the sidewalls of enlarged valve bore
section 200' to provide a sealing engagement between a first chamber
204' of enlarged valve bore section 200' (FIG. 20) and a second
chamber 206' of enlarged valve bore section 200' (FIG. 21). As can
be seen from the figures, enlarged face portion 28'" is larger
in diameter than spool 24'". This arrangement enables a lesser
amount of pilot pressure from solenoid valve assembly 14 to actuate
spool 24'" to overcome the biasing force of spring 26' and
the fluid pressure acting against end face 36" as compared
to the above recited embodiments. However, it should be understood
that enlarged face portion 28'" may be of any size that is
conducive to the particular application, within the physical limits
of control valve system 10'".
[0076] A piston 208' moveably disposed within a piston bore 210'
formed within an enlarged face portion 28'". Piston 208' includes
a seal 212' disposed between piston 208' and enlarged face portion
28'" to provide a sealing engagement between a first chamber
214' of piston bore 210' (FIG. 20) and a second chamber 216' of
piston bore 210' (FIG. 22). A stem 218' extends orthogonally from
piston 208' into enlarged valve bore section 200' through an aperture
219'. Stem 218' is sized to selectively engage end cap 226', as
will be described below. Piston 208' is preferably larger in diameter
than a spool 24'".
[0077] Control valve system 10'" further includes a feedback
passage 224' extending through spool 24'" between front side
chamber 40 and first chamber 214' of piston bore 210'. Accordingly,
feedback passage 224' serves to provide fluid pressure from front
side chamber 40 to act against piston 208' to drive piston 208'
to the left.
[0078] FIG. 20 illustrates control valve system 10'" in a
normal operation mode in which pressurized fluid from fluid inlet
passage 16 is directed into backside chamber 32 of piston member
assembly 34 to drive a piston 62 outward (to the right in the figures).
Specifically, pressurized fluid from fluid inlet passage 16 is provided
in fluid passage 42". As seen in FIG. 20, solenoid valve assembly
14 is energized such that fluid communication is established between
fluid passage 42" and fluid passage 44". Pressurized fluid
is then introduced from fluid passage 44" into first chamber
204' of enlarged valve bore section 200'. The fluid pressure within
first chamber 204' of enlarged valve bore section 200' acts upon
enlarged face portion 28'" of spool 24'" and a portion
of stem 218' of piston 208'. Simultaneously, pressurized fluid is
introduced from fluid passage 42" into fluid chamber 220 and
acts upon end face 36" of spool 24". Once the force exerted
upon enlarged face portion 28'" and stem 218' of piston 208'
from the fluid pressure within first chamber 204' of enlarged valve
bore section 200' is greater than the sum of the biasing force of
spring 26 and the force exerted upon end face 36" of spool
24'", spool 24'" moves to the right until enlarged face
portion 28'" engages a shoulder portion 228'. This movement
of spool 24'" enables fluid to flow from fluid inlet passage
16 into backside chamber 32 of piston member assembly 34, thereby
extending piston 62 outward (to the right in FIGS. 1-4). Accordingly,
when control valve system 10'" is in the position illustrated
in FIG. 20, fluid inlet passage 16, backside chamber 32 of piston
member assembly 34, fluid passage 42", fluid chamber 220, and
first chamber 204' of enlarged valve bore section 200' are all at
the same fluid pressure, namely equal to the fluid pressure of fluid
inlet passage 16.
[0079] Referring now to FIG. 21, solenoid valve assembly 14 is
de-energized and therefore pilot fluid from fluid passage 42"
is prevented from entering first chamber 204' of enlarged valve
bore section 200'. The sum of the biasing force of spring 26 and
the force of fluid pressure in chamber 220 acting upon end face
36" of spool 24'" biases spool 24'" leftward until
enlarged face portion 28'" and stem 218' generally contact
end cap 226'. This leftward movement of spool 24'" enables
fluid communication between fluid inlet passage 16 and front side
chamber 40 of piston member assembly 34, thereby retracting piston
62.
[0080] As can be appreciated from FIGS. 20-22, feedback passage
224' is in fluid communication with front side chamber 40 of piston
member assembly 34 and, therefore, is at the same fluid pressure
as fluid inlet passage 16. The introduction of pressurized fluid
from fluid inlet passage 16 into front side chamber 40 and feedback
passage 224' enters first chamber 214' of piston bore 210' and forces
piston 208' leftward. Due to the physical contact between stem 218'
and end cap 226', any leftward movement of piston 208' causes a
corresponding rightward movement of spool 24'". The pressure
at which this rightward movement of spool 24" occurs is dependent
upon the relative surface areas of piston 208' and end face 36"
of spool 24'" in addition to the biasing force of spring 26,
as described above. As seen in FIG. 22, spool 24'" will continue
to move rightward until spool 24'" blocks fluid inlet passage
16, at which time spool 24'" reaches an equilibrium position
as described above.
[0081] It should be understood that the present variation enables
efficiencies to be realized in the construction of the control valve
system, namely the ease of construction. That is, the construction
of the feedback passage within the spool is simpler than such construction
in the housing. However, the present variation may not afford the
range in flexibility in choosing the appropriate size of surface
areas as compared to the fourth embodiment (FIGS. 15-19).
[0082] With reference to FIGS. 23-28, a variation of the above
principles is described in connection with a fifth embodiment. In
this regard, a control valve system 10"" is illustrated
having a primary spool 15 and a secondary spool 17 slidably retained
in valve chamber 19. Primary spool 15 is shaped to provide controlled
fluid communication between inlet port 16, exhaust ports 18 and
20, a first output port 40 and a second output port 32 depending
upon the axial position of primary spool 15. Primary spool 15 includes
a first end 21 having a retention feature for retaining biaser spring
26. A second end 23 of primary spool 15 abuts a first end 25 of
secondary spool 17. An enlarged chamber 29 receives a second end
27 of secondary spool 17. A circumferential seal 31 around second
end 27 engages the wall of chamber 29 so that the area within chamber
29 defined by second end 27 is sealed off from a pressure relief
passage 33. Second end 27 of secondary spool 17 presents a working
surface having an area greater than either the working surface areas
of ends 21 or 23 of primary spool 15 (which are preferably equal
to each other).
[0083] The control valve system of FIGS. 23-28 is operable in either
a standard mode or an energy saver mode as determined by a selectable
fluid connection between inlet port 16 and first end 21 of primary
spool 15. A fluid passage 35 is included in the valve housing to
provide the selectable connection. A portion of passage 35 is constructed
within an end cap 37 which may be installed in either of two positions,
one that completes the connection between inlet port 16 and first
end 21 of primary spool 15 (as shown in FIGS. 23 and 24) and one
that blocks the connection (as shown in FIG. 25). Alternatively,
passage 35 may include a movable obstruction as shown in FIGS. 26,
27, and 29.
[0084] FIGS. 23 and 24 show the standard mode of operating the
control valve system wherein primary spool 15 and secondary spool
17 move in unison between a first position shown in FIG. 24 and
a second position shown in FIG. 23. In the first position, solenoid
14 is deactivated so that no pilot pressure is applied to second
end 27 of secondary spool 17 and the spring force of biaser 26 urges
spools 15 and 17 toward the left in FIG. 24, thereby providing full
line pressure to first output port 40 and coupling second output
port 32 to exhaust port 20. When solenoid 14 is activated and pilot
pressure is applied to second end 27 of secondary spool 17, the
greater working surface area of second end 27 overcomes the spring
biasing force and the pressure working against first end 21 of primary
spool 15 so that spools 15 and 17 move into the second position
(i.e., toward the right in FIG. 23), thereby providing full line
pressure to second output port 32 and coupling first output port
40 to exhaust port 18.
[0085] A fluid passage 41 couples first output port 40 to the space
between second end 23 of primary spool 17 and first end 25 of secondary
spool 17. When operating in the standard mode (i.e., with first
end 21 of primary spool 15 always at full line pressure), sufficient
force to separate spools 15 and 17 cannot be generated. Consequently,
the spools move in unison.
[0086] FIGS. 25-27 show operation of the control valve system in
the energy saver mode wherein passage 35 is blocked off from the
first end of primary spool 15. Thus, end cap 37 is shown installed
in a reversed position in FIG. 25 so that fluid communication is
disrupted. Alternatively, FIGS. 26 and 27 show a controllable obstruction
that may be used to block passage 35.
[0087] In FIG. 25, solenoid valve assembly 14 is energized so that
pilot fluid from fluid passage 42'" enters chamber 29 via fluid
passage 44'". The pressure working against second end 27 moves
spools 15 and 17 into the second position (now only the force of
bias spring 26 needs to be overcome). Full line pressure from inlet
port 16 is coupled to second output port 32 and first output port
40 is coupled to exhaust port 18.
[0088] FIG. 26 shows the initial position of spools 15 and 17 in
the energy saver mode when solenoid valve system 14 is de-energized,
thereby removing pressure from second end 27 of secondary spool
17. The unopposed force from bias spring 26 moves spools 15 and
17 into the first (i.e., leftmost) position in FIG. 26, resulting
in full line pressure being applied to first output port 40.
[0089] As fluid flows into first output port 40 and to the piston
member attached to it, the pressure builds up to full line pressure.
The building pressure is applied to second end 23 of primary spool
15 through passage 41. Since secondary spool 17 already abuts the
end of enlarged chamber 29, the building pressure between spools
15 and 17 tends to urge primary spool 15 to the right against the
force of bias spring 26 which opens up a space 45 between the spools.
When a sufficient pressure is reached, primary spool 15 enters a
third position as shown in FIG. 27 wherein inlet port 16 is blocked
from both output ports. The pressure at which inlet port 16 is blocked
off depend upon the magnitude of the bias force of spring 26 and
the geometry of the spools, chambers, and ports. The valve works
as a pressure regulator at this predetermined pressure. The present
embodiment has the advantageous ability to regulate at lower pressures
that conventional regulators (e.g., at a predetermined pressure
of about 2 bars).
[0090] In order to maintain alignment between spools 15 and 17,
a central post 47 may be provided on first end 25 of secondary spool
17 for mating with a coaxial socket 49 is second end 23 of primary
spool 15. In an alternative embodiment shown in FIG. 28, the abutting
ends of spools 15 and 17 comprises flat mating surfaces.
[0091] FIG. 29 shows an alternative embodiment wherein a movable
obstruction for selectively blocking passage 35 is comprised of
a screw 51. Screw 51 may be extended into or withdrawn from passage
35 by rotating the screw within a threaded bore intersecting passage
35.
[0092] It should be noted that in the same way that the embodiment
of FIGS. 1-4 can be modified to include a double solenoid pilot
as shown in FIGS. 5-11, the embodiments of FIGS. 15-27 can also
be implemented with a double solenoid pilot.
[0093] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the spirit
and scope of the invention. |