Fluid handling – Larner-johnson type valves; i.e. – telescoping internal valve...
Reexamination Certificate
2000-07-28
2001-10-02
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Larner-johnson type valves; i.e., telescoping internal valve...
C251S231000, C251S249500
Reexamination Certificate
active
06296009
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to large industrial flow control valves, and more particularly, to arm-driven sleeve valves.
Conventional sleeve valves have been employed to control the flow rate and head pressure of fluids in industrial piping systems. Sleeve valves are often utilized for their ability to operate without the moving components of the valve having to work against the head pressure of the fluid being supplied to the valve. A conventional arm-driven sleeve valve comprises a horizontally-oriented, tubular main body, and a tubular gate slidably engaged around the main body for controlling the flow rate of fluid from the valve.
The main body of a conventional arm-driven sleeve valve has a tubular wall that defines a fluid passage configured to receive fluid from a fluid supply line attached to a first axial end of the main body. An imperforate bulkhead at an opposite second axial end of the main body prohibits the fluid from flowing out the second axial end. At least one discharge opening extends through the tubular wall of the main body for discharging fluid from the fluid passage and into a tank or stilling well in which the valve is placed.
The sleeve valve is operated by axial movement of the tubular gate relative to the main body. The tubular gate is generally cylindrical and acts as a sleeve around the main body that can be axially moved between open and closed positions. In the closed position the gate is axially positioned so that all the discharge openings of the main body are axially between opposite ends of the gate. In the open position, the gate is axially positioned to one side of the discharge openings and thereby allows fluid to pass through the discharge openings of the main body into the tank or stilling well. Additionally, the gate can be variably positioned axially between the open and closed positions where the gate will partially cover the discharge openings to control the rate of fluid flow from the main body.
The axial movement of the gate of a conventional arm-driven sleeve valve is provided by a drive system comprised of a pair of swinging arms that translate rotational motion of a shaft into axial motion of the gate. In a convention arm-driven sleeve valve, the shaft of the drive system is mounted to the sleeve valve for rotation about the shaft's longitudinal axis. The arms are mounted to the shaft and extend away from the shaft axis such that as the shaft is rotated about its axis, a distal end of each of the arms will move along an arcuate path. By mounting the shaft to the sleeve valve in a manner such that the shaft axis is perpendicular to the longitudinal axis of the main body and attaching the distal end of each of the arms to opposite sides of the gate, the arcuate motion of the arms moves the gate along an axis of the main body.
Various types of drive mechanisms are used to provide the torque necessary to rotate the shaft of conventional arm-driven sleeve valves. Such drive mechanisms often include a worm gear connected to either a hand-crank or electromechanical motor. It is important to understand that when moving the gate, it is desirable that each arm exert an equal force on the gate to prevent the gate from binding with the main body. For this reason, the drive mechanism of a conventional arm-driven sleeve valve is typically configured to apply torque to the shaft at a location centrally between the arms such that torsional deflection of the shaft will not cause one arm to exert a greater axial force on the gate than the other. Alternative configurations of attaching drive mechanisms include applying torque equally to the opposite ends of the shaft.
While the above mentioned configurations of applying torque to the shaft of an arm-driven sleeve valve may prevent the gate from binding with the main body, such configurations have associated disadvantages. Configurations in which the torque is applied to the shaft centrally between the arms require the shaft to be positioned further from the gate to accommodate gearing or, alternatively, requires more complicated gearing than would otherwise be required. Applying torque to the ends of the shaft allows the shaft to be positioned closer to the gate but requires redundant components and some additional means of ensuring that equal torque is applied to each of the opposite ends of the shaft.
SUMMARY OF THE INVENTION
Among the advantages of the present invention may be noted the provision of a sleeve valve configured such that each of the arms exerts an equal axial force on the gate, regardless of how torque is applied to the shaft. The present invention prevents the gate of the sleeve valve from binding against the main body while driving the rotation of the shaft asymmetrically from only one end of the shaft.
In general, the sleeve valve of the present invention comprises a main body, a gate, a shaft, and a pair of arm portions. The main body has a generally cylindrical exterior surface defining a central longitudinal axis and an internal fluid passage. The gate is slidably connected to main body for controlling fluid flow from the main body in response to axial movement of the gate relative to the main body. The shaft has a longitudinal axis and is mounted to a sleeve valve for rotation about its longitudinal axis. Additionally, the shaft is positioned laterally spaced from the central axis of the main body with the longitudinal axis of the shaft being perpendicular to the central axis of the main body. The pair of arms are mounted on the shaft and extend away from the axis of the shaft toward distal portions of each arm that are connected to opposite sides of the gate. The arms and shaft are configured and adapted so that rotation of the arms around the shaft is prevented by a connection between the shaft and a portion of the arms at a location centrally between the two arms. The central positioning of the connection between the shaft and arms substantially eliminates the possibility of the arms twisting about the shaft relative to each other due to torsional deflection of the shaft. Thus, the rotation of the shaft can be driven asymmetrically from only one of opposite axial ends of the shaft without causing the arms to exert unequal forces on the gate. The present invention thereby allows a simpler more compact drive mechanism to be used to operate the valve compared to conventional central or duel mounted drive mechanisms.
Another aspect of the invention further comprises a sleeve valve in which a single key-pin attachment forms the anti-rotational connection between the pair of arms and the shaft. The use of a single key-pin prevents undesirable twisting of the arms that could otherwise result from uneven wear or partial loosening of separate connections between each of the pair of arms and the shaft.
Other features and advantages will be in part apparent and in part pointed out hereinafter.
REFERENCES:
patent: 4579477 (1986-04-01), Hartman
patent: 5116252 (1992-05-01), Hartman
patent: 5950660 (1999-09-01), Hartman et al.
Hartman Brian T.
Hartman Thomas A.
Howell & Haferkamp LC
Michalsky Gerald A.
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