Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Reexamination Certificate
2000-06-05
2001-09-18
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
C137S115210, C251S051000, C251S052000
Reexamination Certificate
active
06289919
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to valves and more specifically, to delta pressure regulating valves.
BACKGROUND OF THE INVENTION
It is well known in the fluid power and control industry to utilize delta pressure regulating valves (hereinafter “&Dgr;P valves”) to control or regulate the pressure differential between a high pressure side and a low pressure side of a fluid system component such as, for example, a pump, a flow control valve, an accumulator, a heat exchanger, etc. One known application of such &Dgr;P valves is shown in
FIG. 1
, which illustrates a typical arrangement for a fuel control system
10
for a gas turbine engine. The system
10
includes a fuel pump
12
, a servo metering valve
14
having a high pressure side
16
and a low pressure side
18
, a &Dgr;P valve
20
for maintaining a constant pressure differential between the high and low pressure sides
16
and
18
, and a bypass passage
22
for bypassing flow from the high pressure side
16
though the &Dgr;P valve
20
to an inlet side
24
of the pump
12
. The servo metering valve
14
will typically be designed to deliver a fuel flow rate to an engine that is linearly proportional to a command current signal from an electronic engine control (not shown). The constant differential pressure between the high and low pressure sides
16
and
18
provided by the &Dgr;P valve
20
allows for the linear relationship to be maintained between the command current signal and the fluid flow rate delivered to the engine by the servo metering valve
14
.
FIG. 2
shows a more detailed representation of at least one known type of &Dgr;P valve
20
A for use in a fluid system, such as the fuel control system
10
shown in FIG.
1
. The &Dgr;P valve
20
A includes a cylindrical valve piston or spool
30
that translates within a cylindrical bore
32
formed in a sleeve
34
, which is typically provided as a matched set with the valve spool
30
. The sleeve
34
is part of a valve housing
35
that includes a high pressure port
36
that is connected to the high pressure side
16
of the servo valve
14
, a low pressure port
38
that is connected to the low pressure side
18
of the servo valve
14
, and a bypass control port
40
that is connected to the bypass passage
22
to direct a modulated fuel flow thereto from the high pressure port
36
. A cylindrical valve stem
41
is connected to the valve spool
30
for translation therewith, and extends from the spool
30
through the bore opening
66
to outside of the bore
32
. One end
42
of the valve spool
30
is acted on by the fuel pressure on the high pressure side
16
of the servo valve
14
, and the other end
44
of the valve spool
30
is acted on by the fuel pressure on the low pressure side
18
of the servo valve
14
. Thus, the valve spool
30
senses the pressure differential across the servo valve
14
. A helical compression, delta pressure spring
46
, acting through a spring retainer or seat
48
engaged with the valve stem
41
, serves to bias the valve spool
30
toward a delta pressure set point (hereinafter “&Dgr;P set point) where the force on the valve spool
30
created by the high pressure acting on the end
42
is balanced by the force of the spring
46
and the low pressure acting on the end
44
and the stem
41
. An adjustment screw or spacers (not shown) may be used to set the preload of the spring
46
and, thereby, the &Dgr;P set point.
The valve spool
30
modulates the pressure differential by varying a metering orifice or flow control area
52
between the high pressure port
36
and the bypass port
40
to modulate a fuel flow to the bypass flow passage
22
. More specifically, if the valve spool
30
senses excessive delta pressure, the valve spool
30
will be forced toward the low pressure port
38
, compressing the delta pressure spring
46
and enlarging the flow control area
52
to the bypass flow port
40
. This increases the force of the spring
46
and decreases the pressure on the high pressure side
16
, thereby restoring the desired &Dgr;P set point. Conversely, if the valve spool
22
senses insufficient delta pressure, the valve spool will move toward the high pressure port
36
, decompressing the delta pressure spring
46
and reducing the flow control area
52
to the bypass flow port
40
. This decreases the force of the spring
46
and increases the pressure on the high pressure side, thereby restoring the desired &Dgr;P set point.
It is known for fluid systems, such as the fuel control system
10
, to become unstable when there is insufficient damping in the system and if one or more of the components, such as the valve
20
A, is excited at a resonate frequency. While various methods and devices exist to increase the damping of fluid systems and components, they can often add excess cost and/or be difficult to incorporate due to pre-existing constraints in envelope size and hardware configuration. Accordingly, there is always room for improvement.
SUMMARY OF THE INVENTION
It is the principal object of this invention to provide a new and improved &Dgr;P valve with integral damping. It is another object of the invention to provide such a valve for a fuel control system, such a the system
10
.
In accordance with one form of the invention, a valve is provided for regulating the pressure differential between a high pressure side and a low pressure side of a fluid system component device. The valve includes a housing, a valve spool, a valve stem, a spring seat, a damping washer, a first spring, and a second spring. The housing includes a surface, a first bore opening in the surface, a bore extending along an axis between the first bore opening and a second bore opening, and a flow bypass port located in a wall of the bore between the first and second openings. The first bore opening is to receive low pressure fluid from the low pressure side, and the second bore opening is to receive high pressure fluid from the high pressure side. The valve spool is slidably received in the bore for translation along the axis to modulate a fluid flow area between the second bore opening and the flow bypass port. The valve spool includes first and second ends, with the first end being acted on by fluid pressure from the first bore opening and the second end being acted on by fluid pressure from the second bore opening. The valve stem is connected to the valve spool for translation therewith, and extends from the first end through the first bore opening to outside of the bore. The spring seat is engaged with the valve stem. The damping washer has first and second faces and an aperture extending through the washer between the first and second faces. The damping washer is piloted on the valve stem by the aperture and located between the spring seat and the surface. The valve stem is slidably received in the aperture to allow relative movement between the valve stem and the damping washer. The first spring is engaged against the spring seat to bias the valve spool against the fluid pressure acting on the second end of the valve spool. The second spring is engaged between the spring seat and the first face of the damping washer to bias the second face of the damping washer against the surface.
Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.
REFERENCES:
patent: 1809419 (1931-06-01), Muller
patent: 2033396 (1936-03-01), Perrine
patent: 2748947 (1956-06-01), Jay
patent: 2767726 (1956-10-01), Feucht
patent: 2973061 (1961-02-01), Rumsey
patent: 3074428 (1963-01-01), Mancewicz
patent: 3338263 (1967-08-01), Altmeppen et al.
patent: 3606905 (1971-09-01), Fehler
patent: 4064906 (1977-12-01), Berg
patent: 4161189 (1979-07-01), Mueller, Jr.
patent: 4168721 (1979-09-01), Mueller, Jr.
patent: 5232013 (1993-08-01), Morris
patent: 5240036 (1993-08-01), Morris
patent: 5261450 (1993-11-01), Betts
patent: 5285813 (1994-02-01), Quante et al.
patent: 5678604 (1997-10-01), Plauborg et al.
patent: 456187 (1913-08-01), None
Ripley David
Sledd Mike
Hamilton Sundstrand Corporation
Hepperle Stephen M.
Wood Phillips VanSanten Clark & Mortimer
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