Valves and valve actuation – Electrically actuated valve – Rotary electric actuator
Reexamination Certificate
2000-11-22
2003-05-13
Walton, George L. (Department: 3754)
Valves and valve actuation
Electrically actuated valve
Rotary electric actuator
C251S122000, C251S129050, C251S129110, C251S267000
Reexamination Certificate
active
06561480
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a motor-operated valve incorporated in a refrigerating cycle system such as a refrigerator, an airconditioner, and a freezer for controlling a flow rate of a refrigerant or for opening and closing a flow passage.
BACKGROUND OF THE INVENTION
Conventionally, in a refrigerating, freezing, or air-conditioning cycle of a refrigerator, a freezer, an airconditioner of a heat-pump type, or the like, a refrigerant line has a motor-operated valve for controlling a flow rate of a refrigerant or for switching flow passages. For example, a motor-operated valve used in a heat-pump type airconditioner particularly often operates to adequately control a room temperature. Such a conventional valve generates a loud noise in operation, so that the valve is not desirably positioned in a room but is positioned around an outside machine having a heat exchanger. Thus, the expansion valve for adjusting a flow rate of a refrigerant to control a room temperature is positioned in the outside apart from an in-room apparatus. This is disadvantageous for a control performance such as responsiveness of the heat exchanger. Furthermore, a pipe line for delivering a refrigerant from the in-room apparatus to an outside machine must be located in the outside under a high temperature condition, while the refrigerant in the pipe line is cooled by its expansion in the expansion valve in a cooling operation. Even with an insulation layer, a large quantity of heat radiates from the pipe line into the atmosphere, reducing the efficiency of the heat exchanger.
In addition, an apparatus other than such air conditioners, for example a refrigerator, often uses an expansion valve which is more expensive than a conventional refrigerant flow control device such as capillary tubes. That is because a recent refrigerator has a larger capacity and requires a precise temperature control for a freezing space and a vegetable space thereof. Such a refrigerator is disposed in a room, so that a motor-operated valve such as an expansion valve is positioned in the room. A noise generated from the motor-operated valve must be reduced as much as possible.
FIG. 22
shows a motor-operated valve used in such above-mentioned apparatuses as an example. The valve has a valve main body
60
provided with a first opening
62
communicating with a first passage
61
in a downward axial direction thereof, a second opening
64
communicating with a second passage
63
at a side portion thereof, and a valve chamber
65
communicating the first opening
62
with the second opening
64
. On a top portion of the valve main body
60
, there is disposed a housing
67
having a bottom cover
66
. The housing
67
is mounted with a magnet
68
on an outer surface thereof and accommodates a resin-made rotor
71
having a central pin
70
. The rotor
71
is extending downward together with the pin
70
to be inserted into the valve chamber
65
. At a lower end of the pin
70
, there is provided a needle valve
72
moved forward and backward relative to the first opening
62
.
The needle valve
72
has an upper, outer periphery slidably laterally engaging with an inner surface of the valve chamber
65
to constitute a lower guide wall
79
. The rotor
71
has a lower, downwardly extended portion
73
formed with an external thread
74
, and the valve chamber
65
has an inner surface formed with an internal thread
75
engaging with the external thread
74
. Thereby, the rotation of the rotor
71
moves itself upward and downward, since the rotor
71
is engaging with the fixed internal thread
75
through the thread engagement, so that the needle valve
72
integral with the rotor
71
moves upward and downward relative to the first opening
62
to control a fluid flow passing therethrough.
The pin
70
has an upper end
76
projecting from the rotor
71
and opposed to an inner surface of a top portion
77
of the housing
67
. The rotor
71
has an outer periphery opposed to an inner periphery of the magnet
68
. The inner periphery defines an upper, eccentric, first cylinder
78
and a lower, reduced-diameter, second cylinder
80
. The eccentric first cylinder
78
engages the rotor
71
with the magnet
68
not to rotate them relative to each other.
The magnet
68
has a lower end portion extending to an outer periphery of
84
of the valve main body
60
. The lower end portion has a rotor support
87
. The rotor support
87
, as illustrated in
FIG. 22
, can abut against a stopper pin
88
secured to the valve main body
60
. The magnet
68
has an upper end portion defining an upwardly extended portion
90
which can abut against an upper stopper
92
. The upper stopper
92
is an outer peripheral, downwardly extended member of a stopper mechanism
91
secured on an inner peripheral wall of an upper cover of the housing
67
. The housing
67
has an outer cylindrical surface mounted with coils
93
communicating with an outer device via a connector
94
.
In a motor-operated flow control valve
95
having one thus configured needle valve, the application of an electrical power to the magnet
68
rotates the rotor
71
. Thereby, the engagement between the external thread
74
formed in the extended portion
73
of the rotor
71
and the internal thread
75
formed in an inner wall of the valve chamber causes the rotation of the rotor
71
to move upward and downward. This moves vertically the needle valve
72
formed in the pin
70
secured on the rotor
71
, which changes an open area of the first opening
62
to control a flow rate of a fluid passing therethrough.
When the needle valve
72
fully closes the first opening
62
, the rotor support
87
of the magnet
68
abuts against the stopper pin
88
to mechanically stop the rotation of the rotor
71
regardless of a power pulse supply to the coils. Meanwhile, when the needle valve
72
fully opens the first opening
62
, the upwardly extended portion
90
of the magnet
68
abuts against the upper stopper
92
of the stopper mechanism
91
so that the rotor
71
also stops.
The motor-operated valves of various types each having a construction other than the above-mentioned one have been used in a freezing cycle system or the like. For example, Japanese Patent Laid-open No. H. 4-68510 discloses a rotor having a rotation stopper mechanism which has been widely used. Referring to the mechanism, a case of a motor-operated valve has an upper cover fitted with a downwardly extended central rod. The central rod is surrounded by a helical guide ring which vertically slidably engages with a slider. The slider has an outer end engaging with a stopper rod raised from the rotor.
The conventional motor-operated valve illustrated in
FIG. 22
has the rotor having upper and lower projections abutting against the stoppers provided on a case of the rotor. This arrangement stops the rotation of the rotor when the needle valve is in the fully open state or in the fully closed state. However, the motor-operated valve requires the upper and lower stoppers, which increases the number of parts and causes an increase in an assembling man-hour of the valve. This is a disadvantage of the motor-operated valve. The rotation stopper mechanism disadvantageously requires a further increased number of parts and a further increased assembling man-hour, because the mechanism has the central rod wound by the helical guide spring and the stopper rod raised from the rotor.
In addition, the valve element stops in the fully open and closed positions by abutting the members rotating with the rotor against the stoppers. However, since the engaging threads may have a backlash therebetween, the stopping states of the valve element may not be sufficient.
Furthermore, the stopping members rotating with the rotor abut against the stoppers which are positioned radially apart from the central axis of the rotor. This disadvantageously generates a larger chattering noise when the stopping members hit the stoppers by pulses alternately turning the rotor in the normal or reverse direction around
Komiya Yasuo
Nakano Seiichi
Sekiguchi Hideki
Yatsui Tokuji
Kabushiki Kaisha Saginomiya Seisakusho
Long Butzel
Walton George L.
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