Valves and valve actuation – Fluid actuated or retarded – With mechanical movement between actuator and valve
Reexamination Certificate
1998-09-22
2001-04-24
Huson, Gregory L. (Department: 3751)
Valves and valve actuation
Fluid actuated or retarded
With mechanical movement between actuator and valve
C062S160000, C062S324600, C091S459000, C137S487500, C137S625640, C251S129040
Reexamination Certificate
active
06220566
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to valves for use in the fluid circuits of refrigeration and air conditioning systems and, more particularly, to ball valves used as compressor valves, line service valves or expansion valves, incorporating means to achieve incremental valve actuation.
2. Discussion
To significantly improve the overall energy efficiency of a refrigeration or air conditioning system and to minimize the unwanted release of refrigerant from the fluid circuit to atmosphere, it has been considered important to be able to remotely control the actuation, including incremental actuation, of system components, including compressor valves, line service valves and expansion valves.
To this end, modest attempts have been made to design remotely controlled or actuated valves for use in the fluid circuits of refrigeration and air conditioning systems.
One example of an actuated valve which has seen widespread use in the refrigeration and air conditioning industry for remotely controlling the flow of refrigerant through a fluid circuit is a solenoid-operated globe-type valve and is generally illustrated in prior art FIG.
1
.
The valve
200
includes a body member
202
having a first and a second fluid passage
204
,
206
running therethrough which, when combined, provide a fluid passage through the entire valve
200
. Standard fluid fittings
208
located at the ends of the first and second fluid passages
204
,
206
enable the valve
200
to be easily installed in a fluid circuit. Disposed between the first and second fluid passages
204
,
206
at an upper portion
210
of the body member
202
is a solenoid
212
. The solenoid
212
is affixed to the body member
202
by any of several suitable means, such as welding, brazing or soldering, as generally indicated at
214
, or with a threaded connection. The solenoid
212
includes a plunger operator
216
which is disposed for linear movement within the valve body
202
upon energization of the solenoid
212
. At one end of the plunger operator
216
is a globe type plug or closure element
218
that is operable to completely shut off the fluid passage
204
when in the closed position. A spring member
220
is placed about the plunger operator
216
and biased against the closure element
218
. The plunger operator
216
is linearly positionable between a closed position (not shown) and an opened position (as shown in
FIG. 1
) when the solenoid
212
is energized from its de-activated state. In the opened position, the closure element
218
is withdrawn from the valve seat
222
by the electromagnetic force generated in the solenoid
212
, overcoming the bias of the spring member
220
. Fluid is then free to flow through the fluid passages
204
,
206
of the valve as indicated by arrows
224
. In the closed position, the solenoid
212
is deactivated and the biasing force of the spring member
220
causes the closure element
218
to advance into the fluid passage
204
and into engagement against the valve seat
222
. When closed, fluid flow through the valve
200
is prohibited.
It is significant to note that, as illustrated in
FIG. 1
, even when the valve is in the opened position, the closure element of the solenoid valve remains at least partially protruding into the fluid flow stream. Because of this inherent design feature, blockage or interference within the fluid passage is created and, the fluid flow through the valve becomes turbulent, resulting in an increased pressure drop across the valve. The pressure drop, in turn, reduces the efficiency of the valve by allowing a significant amount of energy to be lost from the refrigeration circuit. Consequently, this energy loss presents a design constraint that must be addressed by refrigeration and air conditioning system designers and engineers as they develop refrigeration and air conditioning systems. Often, to compensate for the energy loss, system designers and engineers specify larger, over-sized compressors which exceed the thermodynamic requirements of the refrigeration system application. The use of such oversized compressors is inefficient and a waste of energy.
Solenoid-actuated valves which have been used in the prior art also present other difficulties. One problem results from the fact that there is no control over the speed at which the valve is closed because the switching of the valve between its opened and closed positions occurs nearly instantaneously. As such, the potential exists for the creation of a detrimental condition within the fluid circuit known as a “fluid hammer” effect. When a valve is closed too quickly, a “fluid hammer” caused by the force of the moving fluid against the closure element, can create a significant, momentary spike in the fluid pressure within the valve, often times substantially exceeding the pressure capacity for the valve. In many cases, cracks or breaks which are brought on in the fluid lines by a fluid hammer result in the undesirable loss of refrigerant to atmosphere. In some extreme situations, the fluid hammer effect could cause the valve, itself, to break apart creating an undesirable result.
Also, solenoid-actuated valves typically require a considerable draw of electrical current for their operation. As can be readily appreciated, the closure element of the solenoid-actuated valve must be sufficiently biased by the spring member in order to overcome the force of the pressurized fluid in the circuit and to engage the valve seat to prohibit the flow of fluid through the valve. In turn, the electromagnetic force generated by the solenoid must overcome the spring bias in order to open the valve. This requires that a sufficient amount of electrical energy be received at the solenoid from a remote power source. The amount of energy necessary to operate a solenoid-actuated valve of this type is on the order of 10-12 amps.
Consequently, any efficiency gains to the fluid circuit that are attributable to remote control of the solenoid-actuated valve are more than offset by the efficiency reductions due to the inherent energy losses resulting from flow turbulence and substantial pressure drop across the globe-type valve, the increased operating costs associated with the cost of the valve as well as with the energy required for operation of the valve and, finally, the concerns that could be generated as a result of the occurrence of the “fluid hammer” effect.
For these reasons, ball valves are generally preferred for applications in refrigeration and air conditioning fluid circuits because, among other advantages, they exhibit high efficiency fluid flow characteristics and they allow some degree of control over the speed at which the valve is closed. However, the ball valves used in refrigeration and air conditioning systems today, including compressor valves and line service valves, are primarily (if not exclusively) manually operated.
Attempts have also been made to design a remotely controlled, actuated ball valve for use in refrigeration and air conditioning systems. However, no mechanism for the efficient, controlled actuation of a ball valve disposed within a fluid circuit has, as yet, been embraced by the refrigeration and air conditioning industry.
One prior art actuated ball valve comprised an electric, motor-driven actuation mechanism employing a worm gear. The worm gear, in turn, drove a pinion connected to a stem operator of the ball valve. A limit switch controlling the revolutions of the motor (and worm gear) consequently controlled the rotation of the ball valve between the opened position and the closed position. However, this type of actuated ball valve has not received widespread acceptance in the refrigeration and air conditioning industry for several reasons. One reason is that the amount of torque required to cycle the ball valve between the opened and closed positions necessitates an electric motor having a high amperage electrical draw (e.g. on the order of 15 amps), thereby significantly increasing the power requirements for actuat
Harness & Dickey & Pierce P.L.C.
Huson Gregory L.
Mueller Industries, Inc.
Prunner Kathleen J.
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