Automatic three-way valve

Details Automatic three-way valve Automatic three-way valve

1999-05-21

2001-01-09

Simmons, David A. (Department: 1724)

Liquid purification or separation

Filter

With pump, gas pressure, or suction source

C210S424000, C137S625500, C251S323000

Reexamination Certificate

active

06171495

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to valves and particularly to automatic three-way valves and the method for using same with filters operating with filter aid material, such as diatomaceous earth, in order to prevent such filters from transferring fine particles to the filtered fluid area at the beginning of the filtering operation when the cake is not yet uniformly disposed around the filter element and in many other applications.
BACKGROUND OF THE INVENTION
Three-way valves have many industrial uses and are common in all kinds of assemblies. Most three-way valves are ball valves, manually operated in most cases. In order to operate such valves automatically, an electric or hydraulic motor, or an actuator, must be mounted on the ball valve to shift the interconnection and communication between the valve passages. Actuators and electric motors are both unwieldy, expensive and complex. In addition, ball valves also suffer from a fundamental shortcoming, in that their sealing is achieved by a close fit between the ball surface and the surface of a rigid seat mounted on the valve body. The relatively large friction area is sensitive to entrapped sand or other particles, causing the valve to seize and interfere with the operation of changing the state of communication between the valve passages.
SUMMARY OF THE INVENTION
In accordance with a broad aspect of a preferred embodiments of the present invention, there is provided a method and apparatus incorporating an automatic valve, preferably a three-way valve constructed of a housing having inlet, outlet and drain passages and including an internal close-open timing mechanism. The timing mechanism is adjusted to a predetermined period of time in order to close the drain passage and open the outlet passage or to close the outlet passage and open the drain passage. The opening and closing of passages occurs automatically after a predetermined period of time in response to the starting or stopping of an external source of pressurized fluid such as a pump which provides pressurized fluid to the three way valve.
The automatic three way valve, in accordance with the present invention, comprises a housing having inlet, outlet and drain passages and an hydraulic unit connected to the housing and to an internal movable shaft moving with two stops set apart a predetermined distance and between drain passage and outlet passage. A sealing flange is located around the movable shaft and disposed between the two stops. The stops are adjusted with respect to each other so that the sealing flange moves into sealing relationship with either the outlet or the drain passages. The movable shaft is adjusted to move linearly and freely through a central aperture located on the central area of the sealing flange. The movement of the shaft is limited to the distance traveled until one of the two stops pushes against the sealing flange in order to open either one of the outlet or drain passages and closing the other one of the passages. Controlling the period of time between the entering of pressurized fluid to the inlet passage of the three way valve from a source of pressurized fluid which flows through the inlet passage to the drain passage until the opening of the outlet passage and the closing of the drain passage is an important aspect of the present invention. This period of time is controlled by adjusting the distance between the two stops located on the movable shaft and the size of the passage of pressurized fluid located on the hydraulic unit. A control valve, preferably of a relatively small size, is connected to the pressurized fluid passage located on the hydraulic unit. The control valve is provided in order to control the size of the opening of the pressurized fluid passage and the period of time between the opening or closing of the pressurized fluid flow to the valve and the time of the opening or closing of the outlet or the drain passages.
The method and apparatus of the automatic three way valve described and claimed in the present invention are preferably for the use with filters using filter aid material, such as diatomaceous earth (DE), to prevent penetration of fine particles, usually sediments, to the filtered fluid area which would result in the filtered fluid being contaminated with the fine particles during the first stages of filtration when the cake of filter aid material has still not yet or not completely built itself up around the filter element. The present invention provides features allowing the fine particles to drain separately from the filtered fluid for a predetermined time. After the predetermined period of time has passed, the drain passage automatically closes and the flow of filtered fluid from the filter is directed through the outlet passage to a filtered fluid collection area, such as a pool.


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