Patent Application
20070080309
The present disclosure relates generally to fluid control devices and, more specifically, to a vibration damper apparatus for use with fluid control devices.
Process plants often employ fluid pressure regulators to control the pressure and/or flow of process fluids. One commonly used type of fluid pressure regulator is a direct-operated reducing regulator. Such direct-operated regulators typically have an inlet carrying a relatively high pressure fluid (e.g., a liquid, gas, steam, etc.) that is regulated to a lower pressure at an outlet. In many direct-operated regulators, a spring-biased diaphragm is coupled to a plug or other movable fluid flow control member and is exposed to the pressure of the fluid in a chamber connecting the inlet and outlet.
Movements of the spring-biased diaphragm cause the plug or other fluid flow control member to move into or away from an opening or seat disposed between the inlet and the chamber. More specifically, as the pressure in the chamber and, thus, the outlet, increases, the diaphragm causes the fluid flow control member to restrict or shut-off the flow of fluid from the inlet into the chamber, which tends to decrease the pressure in the chamber and the outlet. Conversely, as pressure in the chamber and the outlet decreases, the diaphragm causes the fluid flow control member to reduce the restriction of fluid flow from the inlet into the chamber, which tends to increase the pressure in the chamber and the outlet. By varying the amount of spring bias applied to the diaphragm, the pressure equilibrium, control point, or set-point of the regulator can be set to achieve a desired outlet pressure that remains substantially constant despite variations in inlet pressure.
In certain fluid control applications, the outlet pressure of some direct-operated pressure regulators may vary (e.g., drift or shift) or become unstable (e.g., oscillate). One particularly problematic fluid control application requires a sanitary regulator design. Sanitary regulator applications such as, for example, food and beverage processing, pharmaceutical applications, biotechnology applications, etc. often require a regulator that facilitates in-place, thorough cleaning of the internal components of the regulator in contact with the controlled fluid. As a result, many sanitary regulator designs utilize a diaphragm that is completely exposed to the flow path of the controlled fluid, thereby minimizing the number of crevices or other areas that may prove difficult to clean during an in-place cleaning operation. However, such complete exposure of the diaphragm to the controlled fluid subjects the entire diaphragm area to the often turbulent flow conditions that are present within a regulator. As a result, the diaphragm may be overly responsive to the flow turbulence and, thus, cause undesirable fluctuations in the position or instability of the flow control member (e.g., the plug) and, thus, outlet pressure of the regulator.
Some known fluid regulators incorporate vibration dampers to reduce undesirable fluctuations and/or instabilities of the flow control member and output pressure. Some of these known vibration dampers are configured as a bushing or seal that surrounds and frictionally engages a shaft or stem that is coupled to a plug or other flow control member. This frictional engagement reduces the sensitivity of the regulator to flow turbulence and/or other sources of vibration that could aversely affect output pressure regulation. Another known vibration damper utilizes an o-ring disposed between a regulator housing and lower spring seat. However, many of these know vibration dampers require the use of a lubricant, which is undesirable in sanitary regulator applications because lubricants can attract and retain dirt and other debris making it difficult or impossible to clean the regulator to the degree needed to satisfy the cleanliness requirements of these applications. Further, many of these known vibration dampers have frictional and, thus, damping characteristics that vary significantly with temperature, thereby making it difficult to ensure accurate and stable regulation in applications that expose the regulator to relatively high and/or widely varying temperatures.
In one example embodiment, a fluid control device includes a housing and a piston having an outer circumferential surface and configured to be responsive to pressure within the housing to control the position of a fluid flow control member within the housing. The fluid control device also includes a guide ring coupled to the housing and having an opening configured to receive at least a portion of the piston, and a vibration damper disposed between the guide ring and the piston to frictionally engage the outer circumferential surface of the piston.
In another example embodiment, a vibration damping apparatus for use within a fluid control device includes a guide ring having an inner circumferential surface, an outer circumferential surface, and a lip extending away from the outer circumferential surface and configured to be clamped between portions of a fluid control device. The guide ring also includes a seat integral with the inner circumferential surface, wherein the seat is configured to hold a compliant ring in frictional engagement with a piston or a movable spring seat.
The example vibration damper apparatus described herein may be advantageously used within fluid pressure regulators (e.g., reducing regulators, backpressure regulators, etc.) to reduce or eliminate vibration or turbulence induced output pressure fluctuations, oscillations, instabilities, etc. More specifically, the example vibration damper apparatus described herein includes a vibration damper, a compliant ring or other vibration damping member that frictionally engages a piston and/or a movable spring seat that, in turn, is coupled to a movable flow control member (e.g., a plug) within a pressure regulator. In the disclosed example, the vibration damper, compliant ring or other vibration damping member includes a spring core that is surrounded at least partially by a polymer jacket, cover or coating. The spring core and jacket cooperate to apply a relatively or substantially constant fictional force to a surface of the piston or movable spring seat over a relatively wide range of temperatures. Further, in contrast to some known vibration damping apparatus, the polymer jacket eliminates the need for lubrication of the vibration damping member, which eliminates the accumulation of dirt and debris, as well as other problems, associated with the use of lubricants within regulators, and particularly regulators for use in sanitary applications.
In contrast to some known vibration damping apparatus, the example vibration damper apparatus disclosed herein also includes a guide ring having a bore or opening that receives the piston or movable spring seat. In the disclosed example, the guide ring is disposed between a housing of the regulator and an outer circumferential surface of the piston or movable spring seat and includes a seat or other suitable structure to hold the compliant ring or other vibration damping member in frictional engagement with the outer circumferential surface of the piston or movable spring seat.
In the disclosed example, the guide ring also includes a circumferential outer lip that is clamped between an upper or first housing portion (e.g., a spring case) and a lower or second housing portion (e.g., a body). In addition to fixing the guide ring to the housing of the regulator, the outer lip of the guide ring also facilitates the secure clamping of a diaphragm to the regulator housing. Still further, in the disclosed example, the guide ring includes an integral stop to limit the travel of the piston or movable spring seat to prevent excessive diaphragm movement or travel.
While the example vibration damper apparatus is described herein in connection with a sanitary regulator application, the vibration damper apparatus, as well the as the teachings associated therewith, can alternatively be used in connection with any other type of regulator, valve, or more generally, fluid control devices to reduce or eliminate undesirable fluctuations, oscillations, and/or any other variations in output pressure and/or flow.
Now turning in detail to
The example regulator 100 includes a housing 104 having a first or upper portion 106, which may be generally referred to as a spring case, and a second or lower portion 108, which may generally be referred to as a body. The first and second portions 106 and 108 may be held together via a clamp 109 or using any other suitable fastening mechanism or technique. The body 108 defines an inlet 110 and an outlet 112, both of which are fluidly coupled to a chamber 114. A movable flow control member 116, which in this example is depicted as a plug, is disposed within the body 108 portion of the regulator 102 and is movable relative to an opening or seat 118 at the interface between the inlet 110 and the chamber 114 to control the flow of fluid of fluid into and, thus, the pressure in the chamber 114. A diaphragm 119 is coupled to the plug 116 and is exposed to the pressurized fluid in the chamber 114. As will be described in greater detail below, as the pressure of the fluid in the chamber 114 changes, the diaphragm 119 is urged toward or away from the seat 118 to cause the plug 116 to increase or reduce a gap 120 between the seat 118 and the plug 116 to regulate the flow of fluid into and, thus, the pressure in the chamber 114 and at the outlet 112.
The regulator 100 further includes a spring 122 that is disposed between an upper spring seat 124 and a piston 126, which includes a second or lower spring seat 128. The piston 126 includes structural features configured to perform multiple functions. More specifically, the piston 126 includes the seat 128 to receive and capture an end of the spring 122. Additionally, the piston 126 is fixed to the plug 116 and provides a rigid backing to the diaphragm 119 and, thus, enables the sensing surface of the diaphragm 119 to remain substantially flat during operation of the regulator 100. In this manner, the displacement of the piston 126 is substantially linearly responsive or related to pressure within the housing 104 (e.g., within the chamber 114) to control the position of the plug 116 relative to the seat 118. The piston 126 also has an outer circumferential surface 130 which, as described in greater detail below, frictionally engages a vibration damper 132.
The example vibration damper apparatus 102 includes a guide ring 134 that has an opening 136, which is configured to receive at least a portion of the piston 126. The guide ring 134 includes a circumferential lip 138 that extends away from the opening 136 and which is configured to be clamped or captured between the portions 106 and 108 of the housing 104. The lip 138 also provides a relatively large flat surface that serves to securely clamp the diaphragm 119 between the housing portions 106 and 108 to minimize or prevent the possibility of the diaphragm 119 pulling out from between the housing portions 106 and 108 and/or fluid leaking from the chamber 114 around the diaphragm 119 and into the spring case or upper housing 106.
With reference to
In the example shown herein, the vibration damper 132 includes a core bias member 142 that is at least partially surrounded by a self-lubricating jacket, cover, or sheath 144. In one example, the bias member 142 is a spring that is configured to drive or urge sides 146 and 148 of the jacket 144 outward, thereby causing the side 146 to frictionally engage the surface 130. Continuing with this example, the jacket 144 is made of a polymer material that enables the vibration damper 132 to engage the surface 130 of the piston 126 with a desired and controlled amount of friction over a relatively wide range of temperatures. One commercially available product that may be used to implement the vibration damper 132 is the OmniSeal product provided by Saint-Gobain, Performance Plastics, of Garden Grove, Calif. In particular, the OmniSeal APS seal, design type 750, may be used to implement the vibration damper 132. However, other types of seals or dampers could be used instead. More generally, the vibration damper 132 may be implemented using any compliant ring-shaped component that provides an amount of frictional engagement with the piston 126 suitable to substantially eliminate spurious or other unwanted movements or vibrations of the piston 126 and, thus, perturbations to the controlled output pressure of the regulator 100.
While the particular example described herein, describes the vibration damper 132 as being implemented using a commercially available seal, the vibration damper 132 is not exposed to the pressurized fluid controlled by the regulator 100 and, thus, there is substantially no ambient fluid pressure differential applied to the vibration damper 132 during operation of the regulator 100. In other words, although the described example uses a commercially available seal to implement the vibration damper 132, the vibration damper 132 is not configured to perform a sealing function but, instead, is configured to apply a controlled amount of friction to the piston 126 to reduce or eliminate the vibrations and/or other spurious movements of the piston 126 during operation of the regulator 100. As a result, the vibration damper 132 reduces or eliminates undesirable fluctuations (e.g., oscillations) of the pressure in the chamber 114 (
Referring to
Prior to and/or during operation of the regulator 100, the spring 122 is preloaded by adjusting a bolt 156 that sets the position of the upper spring seat 124. In particular, turning the bolt 156 clockwise moves the upper spring seat 124 toward the lower spring seat 128 and tends to increase the regulated pressure output by the regulator 100. Conversely, turning the bolt 156 counter-clockwise moves the upper spring seat 124 away from the lower spring seat 128 and tends to decrease the regulated pressure output by the regulator 100. In any case, the bolt 156 is used to set the regulated output pressure of the regulator 100. After adjusting the bolt 156, a locknut 158 may be counter-tightened against the housing to ensure that the position of the bolt 156 and, thus, that the regulated output pressure (i.e., the set-point) does not change after it has been set or adjusted.
During operation of the regulator 100, the diaphragm 119 and, thus, the piston 126 and the plug 116, are responsive to pressure changes in the chamber 114. Specifically, when the pressure in the chamber 114 increases from the equilibrium or set-point pressure, the diaphragm 119, the piston 126, and the plug 116 move toward the upper spring seat 124. This movement tends to decrease the gap 120 between the plug 116 and the seat 118, which tends to decrease the flow into the chamber 114 and, as a result, the pressure in the chamber 114. Conversely, when the pressure in the chamber 114 decreases from the equilibrium or set-point pressure, the diaphragm 119, the piston 126, and the plug 116 move away from the upper spring seat 124. This movement tends to increase the gap 120 between the plug 116 and the seat 118, which tends to increase the flow into the chamber 114 and, as a result, the pressure in the chamber 114. Such direct-operating control is well-known to those of ordinary skill in the art.
In contrast to many known regulators, the vibration damper apparatus 102 includes the vibration damper 132, which is frictionally engaged with the outer circumferential surface 130 of the piston 126. Due to the selection, arrangement, and configuration of the components of the vibration damper apparatus 102, the frictional forces applied to the piston 126 remain substantially controlled or constant over a wide temperature range and without the use of any lubricants on the vibration damper 132 and/or the surface 130 of the piston 126. Further, the magnitude of the frictional forces applied to the surface 130 of the piston 126 are selected to minimize or eliminate the sensitivity of the diaphragm 119 and piston 126 to vibrations of the regulator 100 and/or spurious pressure changes or other transient pressure changes within the chamber 114. As a result, the controlled output pressure of the regulator 100 can remain substantially constant and unaffected by such vibrations and pressure changes or fluctuations.
Although certain apparatus, methods, and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. To the contrary, this patent covers all embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.
