Valves and valve actuation – With means for blocking or disabling actuator – Released by non-valving actuator motion
Reexamination Certificate
2000-08-29
2002-01-22
Kaufman, Joseph A. (Department: 3754)
Valves and valve actuation
With means for blocking or disabling actuator
Released by non-valving actuator motion
C251S215000, C251S296000, C251S335200
Reexamination Certificate
active
06340148
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to an improved valve handle, more particularly, to a valve handle that prevents a valve from being accidentally turned on.
2. Description of the Prior Art
In the process of semiconductor wafer production, various kinds of gasses are required at each stage of the manufacturing process. For instance, in a CVD process, the commonly used gasses are SiH
4
, B
2
H
6
, NH
3
, and hydrogen gas; in a dry etching process, the gases used are CF
4
, CHF
3
, oxygen, and SF
6
; and in an ion implantation the gases used are PH
3
, BF
3
, other frequently used inert gases, etc. Some of these gases are toxic, like PH
3
and BF
3
; some are explosive, such as SiH
4
, with a threshold limit value (TLV) of 0.5 ppm and an explosive energy that is 6 times greater than the conventional explosive TNT. A well designed gas-transportation system for delivering processing gases is mandatory for each wafer production process, and the design of the gas-transportation system will vary with the characteristics of the various types of gases. When dealing with toxic or explosive processing gases, extreme care must be taken to avoid explosions or poisonings due to leaking gas.
Valves are the most commonly seen aspect of a gas transportation system. The purpose of the valves is to control the gas flow, so it is indispensable in the entire production system: from the gas source through many transportation routes, to the reactor and then to an exhaust. Valves can be grouped into two categories based on use: 1) ON/Off type and 2) adjustable type. An ON/OFF valve is used to stop gas flow under certain conditions, such as during maintenance of transportation routes.
Please refer to FIG.
1
.
FIG. 1
is a partial view of a cross-section of a valve used in wafer production processes according to the prior art. As shown here, the valve is a typical diaphragm valve commonly found on the market. The flow control of a processing gas for the valve
10
takes place between the flow passages
21
and
22
. Briefly, gas flow control is achieved by a valve base
31
, which is made from poly-chloro-trifluoroethlene (PCTFE), and by a diaphragm
32
, both of which are located in the vicinity of the opening of the flow passage
21
. The diaphragm
32
moves up and down to open and close the flow passage
21
, and the up and down movement is driven by the stem
41
and the handle
42
.
The stem
41
and the handle
42
of the conventional valve
10
are fastened together with bolts or by welding. As an operator turns the handle
42
, the stem
41
moves up or down, which mobilizes the diaphragm
32
, to which the stem
41
is connected, so as to turn on or off the valve
10
. For instance, when the operator turns the handle
42
clockwise, the diaphragm
32
moves down and stops the flow of the processing gas. Conversely, when the operator turns the handle counterclockwise, the diaphragm goes up and thus turns on the valve
10
. However, although the on/off state is displayed on the handle
42
of the diaphragm valve
10
, mistakenly turning on a valve in some section of the gas transportation system occurs, and not infrequently in a wafer production factory that has hundreds or thousands of valves. As toxic or explosive processing gases can escape into the air due to an improper valve state (i.e., open or closed), the safety of the working environment the lives of workers are put at risk.
SUMMARY OF THE INVENTION
It is therefore a primary objective of this invention to provide an improved manual valve to solve the problem described above.
Another objective of the invention is to provide a valve handle that prevents the valve from being accidentally turned on so as to ensure the safety of the working environment.
In the preferred embodiment of the present invention, a valve handle, which prevents a valve from being mistakenly turned on, has a fixing ring for driving a stem up and down, the fixing ring having at least one stopper. The valve handle also has a knob housing that covers and turns the fixing ring. The knob housing has at least one protrusion located on a top inner side of the housing that works with the stopper of the fixing ring. The protrusion comprises a first perpendicular plane and a slant plane.
When an operator turns the knob housing in a first turning direction, the first perpendicular plane pushes the stopper, causing the fixing ring to turn in the first turning direction and simultaneously making the stem descend, placing the valve in an OFF state. When an operator turns the knob housing in a second turning direction, the slant plane slides past the stopper, and so is unable to move the fixing ring, and the valve at this time cannot be turned to an ON state.
It is a benefit of the present invention that the interaction of the perpendicular and slant planes prevents the valve of the valve from being easily opened. Hence, the valve is less likely to be mistakenly opened by an operator, and thus the dangerous leakage of gasses associated with such mistakenly opened valves can be avoided.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the various figures and drawings.
REFERENCES:
patent: 3193243 (1965-07-01), Billington et al.
patent: 4456222 (1984-06-01), Shen
patent: 4960218 (1990-10-01), Toida et al.
patent: 5026026 (1991-06-01), Sever et al.
patent: 6195819 (2001-03-01), Wang
Bonderer David A
Hsu Wintson
Kaufman Joseph A.
United Microelectronics Corp.
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