Fluid handling – Processes – Cleaning – repairing – or assembling
Reexamination Certificate
2000-04-27
2001-03-27
Lee, Kevin (Department: 3754)
Fluid handling
Processes
Cleaning, repairing, or assembling
C137S015220, C251S315140
Reexamination Certificate
active
06206023
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to valves and, more particularly, to ball valves of the type including a valve seat and a seat retainer, and methods for forming the same.
BACKGROUND OF THE INVENTION
Polymeric ball valves are widely used for a variety of industrial applications. Polymeric ball valves typically provide the advantages of relatively light weight, low cost, corrosion resistance, and the ability to be welded on site into a piping system.
A known method of forming a polymeric ball valve includes providing a polymeric body/end piece and a polymeric end piece. A valve ball is disposed in the body/end piece and the end piece is fused to the body/end piece to enclose the valve ball in an integral valve body. A pair of resilient, ring-shaped seats provide seals between the ball and the body/end piece and the end piece. Each seat is held in place by a respective ring-shaped seat retainer. An example of a valve of this construction is disclosed in U.S. Pat. No. 5,232,201 to Spears et al.
A preferred method for forming a ball valve of the type described includes inserting a first seat, a first seat retainer and the ball into the body/end piece. Thereafter, a second seat retainer, a second seat and the end piece are placed over the ball and the end piece is fused to the body/end piece.
During the assembly procedure, the seats should be maintained in the desired position to ensure proper mating between the seats and the ball. One method for holding the seat retainer, and thereby the seat, in place includes providing flanges projecting inwardly from the body/end piece and the end piece, outer threads on the flanges and inner threads on the seat retainers. The seat retainers are screwed onto the flanges and thereby held in place. However, the threads must be molded, machined or otherwise formed on the body/end and end pieces. The thread formation may add significantly to the cost and inconvenience of manufacturing the valve. In particular, because the seat retainers and the body/end and end pieces are typically formed of polyethylene or polypropylene, care must be taken in forming the threads. Furthermore, care must be taken in screwing the seat retainers on to avoid cross-threading and damaging the threads. Additionally, a tendency may exist to distort the seat as the seat retainer rotates into engagement with the seat, or to apply too much or too little pressure to the seat by under-tightening or over-tightening the seat retainer.
Polymeric ball valves (and other valves including rotatable valve members) may be provided with a gearbox to facilitate rotation of the ball to open and close the valve. Typically, the gearbox includes a casing, a gear reducer and a drive shaft adapted to engage a valve stem which is connected to the ball. Drive means such as an electric motor may be disposed in or on the casing or otherwise associated with the gearbox.
In order to secure the gearbox to a polymeric ball valve, it is known to provide an integral upstanding flange on the valve body. The flange surrounds the valve stem. Holes are formed radially through the flange. The gearbox may be mounted on the flange by inserting bolts through the holes.
The foregoing gearbox mounting arrangement may suffer from a number of potential drawbacks. The provision of an upstanding flange which is strong enough and secure enough to resist torque from the gearbox without failure may add significantly to the weight and to the cost of forming the valve. Moreover, it may be necessary to provide a special bracket on the gearbox to allow mounting on the flange.
SUMMARY OF THE INVENTION
According to embodiments of the present invention, a method for forming a valve includes providing a body piece including an axially extending annular flange having an outer surface and a first element. The first element comprises at least one of a recess defined in the outer surface of the flange and a projection extending from the outer surface of the flange. A valve seat is placed on the flange. An annular seat retainer is provided. The seat retainer has an inner surface and includes a second element comprising at least one of a recess defined in the inner surface of the retainer and a projection extending from the inner surface of the seat retainer. The seat retainer is slid axially onto the flange until the first and second elements snap fit into engagement and such that the seat is thereby retained in position on the flange.
Preferably, the first element comprises a continuous, endless, circumferential, radially extending groove, the second element comprises a continuous, endless, circumferential, radially extending rib, and the step of axially sliding the seat retainer onto the flange includes snap fitting the rib into engagement with the groove.
According to further embodiments of the present invention, a valve includes a valve body defining a cavity and including a flange having an outer surface and a first element. The first element includes at least one of a recess defined in the outer surface of the flange and a projection extending from the outer surface of the flange. A seat retainer is mounted on the flange and has an inner surface. The seat retainer includes a second element including at least one of a recess defined in the inner surface of the seat retainer and a projection extending from the inner surface of the seat retainer. A valve seat is retained on the flange by the seat retainer. The seat retainer is secured to the flange by a cooperative snap fit engagement between the first and second elements. A valve member may be rotatably mounted in the cavity and engage the valve seat.
Preferably, the first element comprises a continuous, endless, circumferential, radially extending groove, and the second element comprises a continuous, endless, circumferential, radially extending rib. The seat retainer is secured to the flange by a cooperative snap fit engagement between the rib and the groove. Preferably, the groove is defined in the outer surface of the flange and the rib extends radially inwardly from the inner surface of the seat retainer.
The valve body may include first and second body pieces. The body pieces may be fused together. Preferably, the body pieces and the seat retainer are formed of polymeric material.
According to embodiments of the present invention, a valve is adapted to receive a gearbox. The valve includes a valve body having a drive opening and a mounting surface adjacent the drive opening. At least one mounting bore is formed in the mounting surface and is adapted to receive a fastener. At least one rigid pin is fixed to and projects from the mounting surface. A rotatable valve member is disposed in the valve body and is operable through the drive opening.
According to further embodiments of the present invention, a valve assembly includes a valve and a gearbox. The valve includes a valve body having a drive opening and a mounting surface adjacent the drive opening. At least one mounting bore is formed in the mounting surface. At least one rigid pin is fixed to and projects from the mounting surface. A rotatable valve member is disposed in the valve body. The gearbox is operable to rotate the valve member through the drive opening. The gearbox includes a casing including a mounting wall positioned adjacent the mounting surface of the valve body. At least one mounting hole is formed in the mounting wall and is disposed adjacent the mounting bore. At least one pin hole is formed in the mounting wall and receives the pin. A drive hole is formed in the mounting wall and communicates with the drive opening. At least one fastener extends through the mounting hole and engages the mounting bore to secure the casing to the mounting surface. The pin resists relative rotational movement of the casing and the valve body.
According to further embodiments of the present invention, a method for mounting a gearbox on a valve of the type having a valve body and a rotatable valve member disposed in the valve body includes placing the gearbox on a mounting surface of the valve
Lee Kevin
Myers Bigel & Sibley & Sajovec
Nordstrom Valves, Inc.
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