Patent Application
20070272307
In one disclosed example, a pressure regulator includes a body having a pressure inlet and a pressure outlet interconnected through a bore within the body. A piston is disposed in the body, fluidly interconnecting the pressure inlet and the pressure outlet forming a passageway and pressure chamber within the bore. The piston is configured to contact a valve seat within the body to control the flow of fluid from the pressure inlet to the pressure outlet in response to a pressure applied to a surface of the piston via the pressure outlet to counteract a loading force supplied by a single spring coupled to the piston.
In another disclosed example, a pressure regulator includes a modular pressure regulator valve assembly fluidly coupled to a pressure inlet and a pressure outlet. The modular pressure regulator valve assembly includes a piston having minimal inlet areas to reduce supply sensitivity and configured to engage a valve seat and to respond to a control pressure to control the flow of fluid between the pressure inlet and the pressure outlet via the valve seat with only the piston and valve seat exposed to the fluid flow.
In general, the example pressure reducing regulator described herein provides a single or unitary regulator body that contains an interior pressure regulating valve to control fluid flow through the regulator. The example pressure regulating valve is a normally-open valve (i.e., at pressures below a predetermined pressure or set point, fluid flows generally unobstructed from the inlet to the outlet) using a single piston and spring to regulate the fluid pressure, and therefore, the fluid flow. The pressure regulating valve accomplishes this by using an output pressure derived from a single pressure source inlet of the regulator body. That is, the output pressure results from a pressure drop across the interior pressure regulating valve that drives the pressure regulating valve, from the outlet or the pressure output side to control valve position. In the preferred embodiment, the pressure regulating valve is based upon a single or unitary piston. The single piston substantially reduces the number of components needed to implement the pressure regulating valve assembly, thereby enabling a more compact design with improved reliability and sanitary operation, while lowering manufacturing and assembly costs. It will also be apparent to one skilled in the art that the design of the pressure reducing regulator, described in greater detail below allows the regulator to be easily used in sanitary operations.
In general, this simple modular design operates using a force balance, in compression, across the piston to maintain the outlet at a predetermined pressure. In the preferred embodiment, the example pressure regulator is configured to provide an increased measuring element area (i.e., an increase in regulator gain or responsiveness to the control pressure) when the outlet pressure falls below a desired, predetermined pressure. The preferred design further includes minimal inlet areas to effectively decouple the output pressure stability from inlet pressure variations. The design also advantageously provides a pressure-assisted shutoff if a fluid leak occurs across the valve seat when the restricting element or valve is closed as explained in greater detail below.
Referring now to
The example regulator [100] further includes a bonnet cap [165], as shown, configured to fit a opening of the body created by a widened portion [190] of the bore to seal the regulator body, thereby forming the pressure chamber [137] between the bonnet cap [165] and the valve assembly [140] on the outlet or output side of the bore [140]. An annular seal [192] is placed within a groove [194] in the bonnet cap [165] to form a pressure-tight seal within the body [110]. The bonnet cap [165] is retained within the body [110] using a bonnet cap retainer [187], such as a common C-ring, that engages an upper annular groove [189]. Alternatively, the bonnet cap may threadably attach to the regulator body to form the pressure chamber [137]. The bonnet cap [165] may also include an integral travel stop [200] (shown in
As shown, the pressure reducing valve assembly [150] can selectively engage a reduced diameter intermediate portion [136] between the passageway [135] and the pressure chamber [137], which forms a valve seat [142] in the body [110]. The pressure reducing valve assembly [150] of the example pressure regulator is comprised of a single piston [160] (i.e. the measuring element), a loading element [170], and at least one annular seal [180]. More specifically, the piston [160] is a generally cylindrical component that slidably engages the bore [140] of the regulator body to selectably interconnect the pressure inlet [125] and the pressure outlet [145] via the passageway [135], the intermediate portion [136] and the pressure chamber [137] of the bore [140]. The piston [160] has a first sensing surface [164] that receives a control pressure (i.e., the pressure in the chamber [137]) via the pressure outlet [145] in the first position (shown in
To control fluid flow, the piston [160] has an enlarged portion [146] shaped to contact the valve seat [142] when the pressure reducing regulator is substantially closed position. The piston [160] may also include a receiving portion [175] preferably configured to receive a loading element or spring [170] to provide a predetermined force to counteract and/or balance an outlet pressure force exerted upon either the first and/or second sensing surfaces [164] and [168]. One of ordinary skill in the art should appreciate that the example piston [160], as shown, has axially opposed first and second inlet surfaces [167] and [169] between the enlarged portion [146] and receiving portion [175] of the piston [160] to substantially offset inlet forces of the piston [160] (i.e., the net force across the surfaces are substantially zero) when inlet fluid pressures are exerted upon them. This allows the forces exerted upon the first and second surfaces [164] and [168], in combination with the loading element force, to dominate output pressure control.
In applications requiring sanitary operation, the piston [160] may also include a first annular channel [182] adjacent to the receiving portion of the piston [160] to incorporate an annular seal [180] (e.g., an o-ring) to form a sealed cavity for isolating the loading element [170] and receiving portion [175] of the piston from the fluid flow. This avoids stagnation of fluid (e.g., beverages such as tea) within the regulator [100]. Alternatively, an annular channel could be placed in the bore to accommodate the o-ring seal (not shown). To eliminate any “air spring” effect of the sealed cavity, the body [110] may also include a vent [153] to permit pressure equalization in the area under the receiving portion [175] of the piston. A second annular channel may also be formed within the enlarged portion [146] of the piston [160] to incorporate an additional o-ring to provide for a resilient seal [148] to engage the valve seat [142]. Such a seal could substantially aid in inhibiting or shutting off of the fluid flow from the inlet [125] to the outlet [145] depending upon the application.
In an alternate example, it should be appreciated that the valve seat may be formed from a resilient material, softer than the body material or the piston material, by placing an annular channel or groove within the body to receive the resilient material thereby forming a soft seat. A corresponding annular portion of the piston may be slightly enlarged from the diameter of the first surface [164] of the piston [160] to engage the resilient material to facilitate shutoff (e.g., placing the soft seal in the body as opposed to the piston).
During operation of the example regulator, one of ordinary skill in the art would appreciate that when the piston [160] is in the first position (shown in
From the above description, it should be evident that the pressure valve assembly [150] has two response characteristics or gains during operation. A first response characteristic or gain when the pressure valve assembly [150] is fully open is related to the annular area of the first sensing surface [164]. A second response characteristic or gain occurs when the pressure valve assembly is not in contact with the travel stop [200] and is related to the area of the first and second sensing surfaces [164] and [168]. These two response characteristics or gains allow the example regulator to respond to the countervailing loading forces in a manner such that the regulator has increased or enhanced responsivity to deviations in output pressure when near the set point or desired output pressure (e.g., the pressure regulating valve assembly [150] is in the second position).
In operation before the pressure is controlled, the loading element [170] biases the piston [160] away from the valve seat [142] and into intimate contact with the integral travel stop [200] to permit substantially unrestricted fluid flow from the pressure inlet [125] to the pressure outlet [145]. The fluid flows from the inlet [125] through the passageway [135] and momentarily pressurizes the passageway [135] and pressure chamber [137] to a pressure nearly equal to the inlet pressure. As the outlet pressure increases in the pressure chamber [137], a increasing force is exerted upon the first sensing surface [164] of the piston in a predetermined manner such that a force, related to the annular area of the first sensing surface [164], counteracts the loading force of the loading element [170] and the piston [160] will begin to move, in compression, against the loading element [170] and towards the valve seat [142]. Prior to piston movement in the first position, the control pressure only acts upon the first sensing surface [164] of the piston [160] to generate a force related to the first gain of the regulator. Once the pressure in the pressure chamber [137] is sufficient to generate a force to overcome the initial loading force, the piston [160] moves towards the second position.
In the second position (as shown in
It may be appreciated that when the annular surface [146] engages the valve seat [142] (i.e., valve shutoff) the seal [148] substantially closes the pressure valve assembly and essentially prevents flow between the pressure inlet [125] and the pressure outlet [145]. If there is a leak between the seal [148] and the valve seat [142], the output pressure may rise above the set point. In such a condition, the additional fluid flow creates an increase in the pressure of the outlet side of the pressure valve assembly [150] and an additional closure force is generated against the first and second sensing surfaces [164] and [168]. The additional force generated by the leak increases in proportion to the pressure differential across the seat to “positively shut-off” the pressure valve assembly [150] to quickly return the output pressure to the set point.
From the foregoing description, it should be apparent that this modulation of the piston [160] occurs continually during regulator operation to control the fluid flow through the regulator based upon the outlet pressure. The piston [160] continually operates in compression about the valve seat [142] under a force balance during pressure regulation. That is, when the pressures urging the piston away from the seat and toward the seat are in balance, the pressure at the outlet [145] is substantially equal to the predetermined set point as substantially determined by the sensing surfaces [164] and [168] and the spring rate of the spring or loading element [170].
Thus, it should be appreciated that the multiple response characteristics or gain of the regulator improves the overall sensitivity of the outlet pressure regulation to load changes and the reduced and offsetting inlet areas substantially eliminates susceptibility of outlet pressure deviations to inlet pressure variations. Further, it should also be appreciated that the regulator body, piston, and bonnet cap may be made of metal such as, for example, brass, stainless steel, or any other metal or material suitable for the intended application of the pressure reducing regulator, including engineered plastics such as Delrin®, from DuPont E I De Nemours & Co. of Wilmington, Del.
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.
