Valves and valve actuation – Detachable actuator – Rotary valve
Reexamination Certificate
2002-01-03
2004-06-01
Mar, Michael (Department: 3754)
Valves and valve actuation
Detachable actuator
Rotary valve
Reexamination Certificate
active
06742765
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an operating device having an output shaft for rotating an object to be operated, and a valve system having such an operating device and a valve serving as the object to be operated. In particular, the present invention relates to a spring return type operating device having a return spring for rotating an object to be operated in a return direction, and a spring return type valve system having this kind of operating device and a valve.
2. Description of the Related Art
For flow control of fluid that flows through a fluid channel, such as water, steam, gas, air, and oil, valve systems of spring return type and the like are used. As exemplarily illustrated in
FIG. 11
, a conventional spring return type valve system includes a valve
70
inserted in a fluid channel (not shown), a return spring unit
80
mounted on the valve
70
, and an electric actuator
90
mounted on the return spring unit
80
.
The return spring unit
80
has a housing
81
, a rotating shaft
82
, and a return spring
87
interposed therebetween. The return spring unit
80
is configured so that the spring force from the return spring
87
rotates the rotating shaft
82
and a valve shaft
72
of the valve
70
coupled thereto in one direction, e.g., in the direction that closes the valve. The electric actuator
90
rotates its output shaft
92
with a motor
96
via a reduction mechanism
97
consisting of a gear train so that the valve shaft
72
coupled to the actuator output shaft
92
is rotated against the spring force of the return spring
87
through the medium of the rotating shaft
82
of the return spring unit
80
.
Thus, in the spring return type valve system, the valve shaft
72
and a valve element
75
integral therewith are rotated by the electric actuator
90
to a predetermined rotational position so as to adjust the opening of the valve
70
, whereby the flow rate of the fluid flowing through the fluid channel is controlled. When the energization to the actuator
90
is interrupted, the valve shaft
72
is rotated in the closing direction by the spring force of the return spring
87
to close the valve
70
.
In the conventional spring return type valve system described above, the housing
81
of the return spring unit
80
includes an outer housing and an inner housing. The outer housing has a lower flange
84
thereof fixed to a flange
74
of the housing
71
of the valve
70
with bolts
100
. The inner housing is fitted to a socket part
73
of the housing
71
and supports the rotating shaft
82
of the return spring unit
80
. A recess
83
formed in the inner housing accommodates a joint
110
for coupling the rotating shaft
82
to the valve shaft
72
. Meanwhile, the housing
91
of the electric actuator
90
includes an upper housing and a lower housing. The upper housing accommodates the reduction mechanism
97
. The lower housing fits a socket part
85
of an upper flange
86
of the return spring unit
80
, and has a flange
95
which is fixed to the upper flange
86
with bolts
101
. The lower housing has a recess
93
which accommodates a joint
111
for coupling the actuator output shaft
92
to the rotating shaft
82
of the return spring unit
80
.
As described above, in the conventional spring return type valve system, the top end portion of the valve shaft
72
, the joint
110
, and the bottom end portion of the rotating shaft
82
are accommodated in the recess
83
of the housing
81
. The top end portion of the rotating shaft
82
, the joint
111
, and the bottom end portion of the output shaft
92
are accommodated in the recess
93
of the housing
91
. These shafts and joints are therefore invisible from exterior, sometimes working against the assembling and disassembling operations of the valve system.
Take, for example, the case of coupling the valve shaft
72
to the joint
110
. When the valve shaft
72
is fitted into the joint
110
, a flat-faced part
72
a
formed on the valve shaft
72
must be aligned to a flat part of a fit hole formed in the joint
110
. The same holds true when one end portion of the rotating shaft
82
is fitted into the joint
110
, and when the other end portion of the rotating shaft
82
and the output shaft
92
are fitted into the joint
111
. In
FIG. 11
, the reference numerals
82
a
,
82
b
, and
92
a
show the flat-faced parts. In the conventional system, the accommodation of the joints
110
and
111
in the recesses
83
and
93
of the housings
81
and
91
makes the directions of the flat-faced parts invisible from exterior, deteriorating the workability in coupling the corresponding ones of the valve shaft
72
, the rotating shaft
82
, and the output shaft
92
with the joints
110
and
111
.
When such coupling operations are performed under a work environment where neither the socket part
73
between the housings
71
and
82
nor the socket part
85
between the housings
81
and
92
can be visually observed from exterior, the peripheral portions of these socket parts and the openings of the housings can possibly be damaged or deformed. In addition, foreign matter adhering to the socket parts and rust forming on the socket parts are easy to be passed undetected, so that an assembly failure can occur due to the foreign matter and rust.
In cases where the electric actuator
90
suffers a breakdown that the output shaft
92
becomes unrotatable due to such reasons as a gear breakage in the reduction mechanism
97
, the electric actuator
90
is detached from the valve system for repair. On this occasion, if under a work environment where the rotational position of the valve shaft
72
cannot be observed visually from exterior, the operator can possibly remove the bolt
101
despite incomplete closure of the valve
70
. In this case, the entire electric actuator
90
might rotate abruptly due to the spring force from the return spring
87
. With valves of larger sizes in particular, the return spring
87
has a great spring force and it is sometimes impossible for the operator to quickly hold the electric actuator
90
from rotating with strong force. Moreover, when the electric actuator
90
is detached with the valve
70
open, the load on the return spring
87
decreases rapidly. The result is that the spring force from the return spring
87
rotates the valve shaft
72
sharply in the closing direction. Such sharp closure of the valve
70
can cause a water hammer, possibly breaking the valve
70
.
In assembling/disassembling the valve system of the type shown in
FIG. 11
, the electric actuator
90
is detached before the lower flange
84
of the return spring unit
80
is attached to or detached from the flange
71
of the valve
70
by using a screwdriver or other tools. If the valve system is configured such that the upper flange
86
of the return spring unit
80
has a diameter considerably greater than that of the lower flange
84
, or that the two flanges have a considerably small gap therebetween, the tools to loosen and tighten the bolt
100
interferes with the upper flange
86
, finding the operation difficult. Using an L-tipped tool to operate laterally from the housing
81
deteriorates workability.
Moreover, in the conventional valve system shown in
FIG. 11
, the housing
81
of the return spring unit
80
and the housing
71
of the valve
70
are in direct contact with each other. When the object to be controlled by the valve system is hot fluid such as steam, the valve
70
becomes high in temperature. Therefore, the housing
81
also becomes high in temperature because of the heat conducting from the valve
70
, which makes it difficult to detach the return spring unit
80
. In addition, the heat conducting from the valve
70
thermally degrades the return spring unit
80
and the actuator
90
. On the other hand, when the valve
70
is cold due to coolant fluid, the return spring unit
80
and the actuator
90
decrease in temperature with internal condensation, becoming prone to rust and short-circuit b
Miyazaki Takumi
Takano Tomohiro
Frishauf Holtz Goodman & Chick P.C.
Keasel Eric
Mar Michael
Yamatake Corporation
LandOfFree
Operating device and valve system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Operating device and valve system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Operating device and valve system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3335721