Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2001-05-01
2003-07-22
Trieu, Van (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S686300
Reexamination Certificate
active
06597290
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a valve-position output apparatus for outputting positions of a valve.
BACKGROUND OF THE INVENTION
With reference to
FIG. 8
, a conventional valve-position output apparatus will be described.
FIG. 8
is a schematic explanatory view of the conventional valve-position output apparatus, wherein FIG.
8
(
a
) shows the state when a valve (not shown) is located at a fully closed valve-position and FIG.
8
(
b
) shows the state when the valve is located at a fully opened valve-position. A pair of first and second arms
02
,
03
are attached to a valve shaft
01
of the valve. The valve shaft
01
and the arms
02
,
03
are arranged to rotate together in sync with open and close operations of the valve. At the fully closed valve-position shown in FIG.
8
(
a
), the first arm
02
rotates a lever
07
of a limit switch unit
06
counterclockwise to turn on a first limit switch (not shown). On the other hand, at the fully opened valve-position shown in FIG.
8
(
b
), the second arm
03
rotates the lever
07
of the limit switch unit
06
clockwise to turn on a second limit switch (not shown). As described above, the limit switch unit
06
includes the pair of opened valve-position and closed valve-position limit switches. Thus, it is necessary to provide three or four wirings for externally outputting signals from the limit switches.
In the case that a valve-position output apparatus is constructed in such a mechanical structure, it is difficult to sufficiently process data of the valve positions and in particular, to adequately conduct an initial setting in order to accurately detect the valve positions. Further, during open and close operations of the valve, the conflict between the arms
02
,
03
and the lever
07
causes an undesirable noise and the wear of the arms
02
,
03
and the lever
07
. Furthermore, when the valve is moved between the fully opened valve-position and the fully closed valve-position which is spaced apart from the fully opened valve-position at an angle of about 90-degree, the conventional valve-position output apparatus may detect the fully opened and closed valve-positions, but may not detect any valve positions in a transition angle or intermediate angle where the valve is being moved between the fully opened and closed valve-positions.
SUMMARY OF THE INVENTION
In order to solve the aforementioned problems, it is an object of the present invention to provide a valve-position output apparatus capable of adequately detecting valve positions on an optical basis.
According to a first aspect of the present invention, there is provided a valve-position output apparatus comprising an interlocking member arranged to move in sync with the open and close operations of a valve, a position detecting aperture formed in the interlocking member, an optical encoder having a light-emitting section and a light-receiving section which are arranged opposed to each other with interposing the interlocking member therebetween, digital valve-position signal generating means for generating a digital valve-position signal on the basis of a signal from the optical encoder, and abnormality determining means for determining an abnormality to generate an alarm signal, by judging whether the valve is located in a transition angle defined between a fully opened valve-position and fully closed valve-position on the basis of the digital valve-position signal from the digital valve-position signal generating means and whether the time period in the transition angle exceeds a predetermined time. The abnormality determining means determines the abnormality when the valve is located in the transition angle for a period of time which exceeds the predetermined time.
In the first aspect of the present invention, the optical encoder is applied to the valve-position output apparatus. This provides reduced mechanical wear of parts and enhanced durability of the valve-position output apparatus. Further, noise arising from operations may be reduced and thereby undesirable noise of the valve-position output apparatus may be sufficiently reduced. Furthermore, contact points or the like may be reduced and thereby undesirable spark or the like may be prevented as least as possible. In addition, any valve positions including those in the transition angle defined between the fully opened and fully closed valve-positions may be readily detected. Since the encoder applied to the present invention is not a magnetic encoder, the valve-position output apparatus of the present invention may not be adversely affected by an external magnetic field and may not go against the external magnetic field.
The valve-position output apparatus of the first aspect of the present invention is also provided with the abnormality determining means. Thus, when the valve is stopped at the valve position in the transition angle, the alarm signal may be output.
According to a second aspect of the present invention, there is provided a valve-position output apparatus comprising an interlocking member adapted to move in sync with open and close operations of a valve, a position detecting aperture formed in the interlocking member, an optical encoder having a light-emitting section and a light-receiving section which are arranged opposed to each other with interposing the interlocking member therebetween, digital valve-position signal generating means for generating a digital valve-position signal on the basis of a signal of the optical encoder, and D/A converting means for converting the digital valve-position signal from the digital valve-position signal generating means into an analog signal. The D/A converting means is arranged to add a certain value to the digital valve-position signal so as not to make the analog signal have a zero value at a fully opened valve-position and fully closed valve-position.
In the second aspect of the present invention, the valve-position output apparatus is provided with the optical encoder. Thus, the effects yielded by the optical encoder are provided as with the valve-position output apparatus of the first aspect of the present invention. In addition, the valve-position output apparatus of the second aspect of the present invention includes the D/A converting means. This allows analog signals to be output despite of applying the optical encoder. Further, since the D/A converting means is arranged to add a certain value to the digital valve-position signal, the output analog signal does not become zero at the fully opened valve-position and fully closed valve-position in a normal state. Thus, when the output analog signal becomes zero, it may be judged as an abnormal state.
According to a third aspect of the present invention, there is provided a valve-position output apparatus comprising an interlocking member arranged to move in sync with open and close operations of a valve, a position detecting aperture formed in the interlocking member, an optical encoder having a light-emitting section and a light-receiving section which are arranged opposed to each other with interposing the interlocking member therebetween, digital valve-position signal generating means for generating a digital valve-position signal on the basis of a signal of the optical encoder, D/A converting means for converting the digital valve-position signal from the digital valve-position signal generating means into an analog signal, and ON-OFF signal generating means for generating ON and OFF signals. The ON-OFF signal generating means generates the ON signal at one of a fully opened valve-position and a fully closed valve-position and generates the OFF signal at the other of the fully opened valve-position and the fully closed valve-position.
In the third aspect of the present invention, the valve-position output apparatus is provided with the optical encoder. Thus, the effects yielded by the optical encoder are provided as with the valve-position output apparatus of the first aspect of the present invention. In addition, the valve-position output apparatus of the thi
Armstrong Westerman & Hattori, LLP
Trieu Van
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