Flexible rotor valve seal and ganged rotor valve...

Fluid handling – Systems – Multi-way valve unit

Reexamination Certificate

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C137S625110, C137S625470

Reexamination Certificate

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06308739

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention is an improved flexible rotor valve seal and an improved ganged rotor valve utilizing the seal.
More particularly, this invention is an improvement of the seal disclosed in Flexible Seal for Rotor Valves, U.S. Pat. No. 4,548,385, Oct. 22, 1985, by one of the present inventors. The improved seal permits the manufacture of a novel ganged multiway rotor valve, e.g. an 8-way value.
The rotor valve seal of U.S. Pat. No. 4,548,385 works excellently in the usual applications for which it was designed. However, when the valve has an extended rotor and a multiplicity of ports, the seal of the patent provides such a large contact area that rotor movement is unduly stiff or impeded requiring undue force to turn the rotor or a larger drive motor than may be necessary. Also, because the plastic of the seal expands with heating, it is desirable to reduce the mass thereof as much as possible. In addition, the expansion of the seal material upon heating also leads to, or adds to, stiff or impeded rotor movement.
The seal of the patent is characterized by having a rectangular shape that fits or slides into a flat-bottomed channel in the valve rotor that lies about the port to be sealed. In a 4-way valve with the ports spaced 90 degrees about the rotor, 4 such seals would be used each having an opening registering with the ports of the rotor and valve body. The outer surface of the seal is curvilinear, mating with the curvature of the valve body. As is shown in the patent, the inner flat surface of the seal mates with the flat bottom of the channel in the rotor and has a circular groove about the port to be sealed which groove retains an O-ring. The rectangular shape of the seal works well, but with the particular design of the seal device, a better seal is achieved with increased internal pressure within the valve. While increased pressure provides for a better seal, it also leads to increasingly stiff action of the valve requiring increasing force to turn the rotor. In addition, the rectangular shape of the seal includes comers which can be collection points for particulate contaminants, also leading to an increase in the force or torque required to turn the rotor and operate the valve.
Thus it would be desirable to have a rotor valve seal and valve with reduced thermal expansion of the components within the valve, reduced potential collection points for contaminants, and a seal mechanism that does not require increased internal pressure to provide a tighter seal. It would be desirable to have a rotor valve seal and valve that would always be operable with low amounts of torque regardless of temperature, pressure within the valve and contaminants.
SUMMARY OF THE INVENTION
It has now been found that the seal can be just, if not more effective, if it is circular rather than rectangular. This reduces the surface area of the seal in contact with the valve body and thus the force required to turn the rotor. [The O-ring—the flexible sealing mechanism that energizes the seal—and its channel operate in the same manner as illustrated in the patent, except that the sealing force of the O-ring around the circumference of the port in the seal is more uniform, i.e. as the seal of the patent was rectangular, the force developed by the fluid pressure within the port against the inner, circular wedge was not uniformly distributed around the outer portions of the seal.] The sealing force of the O-ring around the circumference of the port in the seal of the present invention is more uniform than that of the prior art U.S. Pat. No. 4,548,385. Because the seal of the prior art patent was rectangular, the force developed by the fluid pressure against the inner, circular wedge was not uniformly distributed around the outer portions of the seal. The present design solves this problem using a seal that provides uniform pressure. Further, the present invention, that does not have corners avoids the buildup of contaminants as occurs with the rectangular design of the prior art. The buildup of contaminants can lead to binding of the valve, and at least increasing force required to turn the rotor. This buildup is avoided in the present invention.
In addition the prior art patent uses a deformable seal material which has a much greater coefficient of thermal expansion than that of the surrounding metal valve parts. This combined with the relatively large amount of the seal material used in the rectangular seal and the irregular shape of the seal results in the seal experiencing vastly varying amounts of thermal expansion within itself. This creates a thermal expansion problem that is difficult to control and can cause the valve to bind, and also can weaken the seal.
The design of the present invention reduces the contact area of the solid seal and that of the ported seal compared to the prior art patent to Barbuto. The reduced contact area results in decreased frictional seal resistance, decreased thermal expansion and therefore decreased effort required to operate the valve.
The seal of this invention is then a disc of a rigid but deformable plastic, e.g. a glass or carbon fiber reinforced plastic, preferably one offering a low coefficient of sliding friction, such as a polytetrafluoroethylene. This disc is preferable machined but in some instances can be compression molded.
The disc, if not used to seal off an entry or exit port, has a central, circular port and its front surface is a portion of a cylindrical surface that is blemish free and without nicks and scratches. The front surface matches the curve of the valve body. The back surface of the disc is usually flat and has a circular groove therein equidistant about the central port to accommodate a flexible sealing mechanism, e.g. an O-ring. The depth of the groove preferably does not exceed 90 percent of the overall thickness of the seal. While the back of the disc is usually flat, it can be convex or concave as the application may require.
The seal can have any diameter, e.g. from 0.5 to 100 inches, with 1 to 24 inches being common. The flexible sealing mechanism can be an O-ring or can be square in cross-section. Quad rings are particularly useful. The flexible sealing mechanism “energizes” the seal and is of a flexible elastomeric or deformable material such as Delrin or Teflon (trademarks of E.I. DuPont de Nemours & Co.), a polyvinyl chloride, a polysulfone, a polyolefin (polyethylene), vulcanized rubber or the like.
The impart a degree of toughness and resistance to damage and cold flow the plastic of the disc is preferably reinforced as with 15% to 35% glass or carbon fibers or brass or sintered steel powder or similar materials.
The improved ganged rotor valve of this invention permitted by the improved seal comprises a valve body having a cylindrical rotor chamber into which fits a rotor. The rotor has several independent flow passageways or bores therein. One passageway can go from one level to another but more usually will go directly through the rotor. The valve body has inlet and outlet ports that mate with the rotor passageways. While at a minimum there will be at least two sets of inlets and outlets in the valve body spaced along the length thereof, i.e. an upper and a lower set, there will usually be a pair at each level along the length of the valve body with mating passageways or bores there through in the rotor for each set. In the following description there are a pair at spaced upper and lower levels of the valve.
The valve seal of this invention is inset into a circular seat in the cylindrical surface of the rotor about the end of each of the openings of the bores or passageways. The port of the seal, if it has one, aligns with the corresponding openings. The outer surface of the cylindrical seal of the disc has about the same radius of curvature, preferable slightly less, than that of the cylindrical surface with which it is in sealing contact. The groove at the bottom of the seal holding the flexible sealing mechanism operates against the disc urging the cylindrical surface of the

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