Electricity: circuit makers and breakers – Multiple circuit control – Pivoted contact
Reexamination Certificate
2002-01-22
2003-02-25
Enad, Elvin (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Pivoted contact
C200S0830SA
Reexamination Certificate
active
06525286
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a triple action pressure switch, which includes a function of detecting occurrence of abnormally high or low pressure in a refrigerant system of a refrigerator air conditioning system and of turning on an electric circuit triggered by detection, and includes also a third function of turning on/off other electric circuits accompanying the refrigeration system independently from the above-mentioned functions.
Specifically, the third function is used for turning on/off a fan motor of a condenser provided inside the refrigerating cycle.
DESCRIPTION OF THE RELATED ART
The Applicant of the present invention has already proposed a triple action pressure switch having the above-mentioned function (Japanese Patent Publication No. H7-114094).
The structure and operation of the above-mentioned conventional triple action pressure switch will be explained with reference to FIG.
3
and FIG.
4
.
FIG. 3
is a vertical cross-sectional view indicating the outline of the structure of the conventional triple action pressure switch, and
FIG. 4
is a graph schematically indicating the characteristics of the operating pressure. The triple action pressure switch shown in
FIG. 3
is illustrated upside down.
As is shown in
FIG. 3
, the switch of the conventional triple action pressure switch is constituted by assembling a housing
1
, a switch case
2
, a diaphragm
22
, a first snap disc portion
3
, a first sliding member
4
, a second snap disc portion
5
, a second sliding member
6
, a third snap disc portion
7
, a second actuating rod
24
, a first actuating rod
23
, a first electric switch segment SW
1
, and a second electric switch segment SW
2
, in a manner shown in FIG.
3
.
The housing
1
is formed using galvanized mild steel or aluminum alloy. The housing
1
has at its upper region a coaxial path P connecting to the refrigeration system, that guides the pressure of the refrigerant to a pressure accepting chamber inside the housing.
The switch case
2
is formed using insulative material such as glass-fiber reinforced polybutylene telephthalate (PBT). The switch case
2
is divided via a divisional wall A into an upper hollow B for storing functioning components of the switch, and a lower hollow C for storing two pairs of terminal members
12
,
13
, and
19
(only one of the two is shown), a total of four terminal members, which pierce through the divisional wall A downwardly in a manner so that the two pairs are orthogonal to each other.
The upper hollow B of the switch case
2
is assembled with the housing
1
, is fixed by caulking the lower end of the housing
1
in a manner shown in the drawing, to form a space B for storing the pressure switch portion therein. The outer wall of the lower hollow C is assembled with a connector of an electrical system of the refrigeration system.
The diaphragm
22
is formed using a thin film of polyimide resin, for example, and is fixed air tightly between the housing
1
and the switch case
2
with a gasket
21
made of elastic material during assembling of the housing
1
and the switch case
2
. The diaphragm
22
divides the space B and the fluid space connecting to the path P, and functions to prevent the refrigerant gas from penetrating into the switch case, and to transmit the refrigerant pressure to the pressure transmitting members inside the switch case.
Each of the first, second and third snap disc portions used in the triple action pressure switch are formed of so-called inversion plates having dish-like shapes with a region projecting from one of the surfaces and having a slope section at the periphery thereof, and having a hysteresis property that the projecting region inverts to the opposite direction when a pressure larger than a predetermined value is provided from the projecting region side, and inverts again to the original position when the pressure decreases below the predetermined value.
By constituting the snap disc portion using a plurality of inversion plates, durability can be enhanced as well as achieving a design minimizing the dispersion of operating values. However, there arouses a fear of friction occurring between each surfaces of the snap discs contacting each other, causing unstable operation of the snap discs. In order to reduce the friction, a lubricant containing a small amount of solid molybdenum disulfide powder is applied to the interface of the layered snap discs. This results in stabilizing the operation of the snap discs incredibly.
The first snap disc portion (inversion plate)
3
is formed by layering a plurality of inversion plates, and the peripheral rim thereof is stored to a snap disc receiver provided to the upper surface of the first sliding member
4
and is stopped by an outer peripheral wall
4
a
, so that the upper surface of the projecting region and the slope portion of the first snap disc portion
3
abuts against the lower surface of the diaphragm
22
.
The first snap disc portion
3
functions to sense the intermediate pressure PM and PM−DELTA PM.
The first sliding member
4
includes the outer peripheral wall
4
a
forming the snap disc receiver to the upper surface thereof, a concentrical annular protrusion
4
b
to the lower surface thereof, and a hollow hole
27
to the center thereof. The outer periphery of the first sliding member
4
slides directly against the inner wall of the switch case
2
. The peripheral rim of the first snap disc portion
3
stored inside the snap disc receiver is stopped against the inner surface of the outer peripheral wall
4
a
of the first sliding member
4
. The first actuating rod
23
is positioned so as to pierce through the hollow hole
27
. The annular protrusion
4
b
is positioned so as to abut against the upper slope portion of the second snap disc portion
5
.
The second snap disc portion (inversion plate)
5
is formed using three snap discs, and includes a hole H at the center thereof. The annular protrusion
4
b
of the first sliding member
4
abuts against the upper slope portion of the second snap disc portion
5
. The hole H provided at the central axis of the second snap disc portion
5
does not interfere with the first actuating rod
23
, and the rod pierces freely therethrough. Generally, the snap disc having a hole suffers from defects such as having large dispersion in operation, and having inferior durability. By constituting the same in a unit of three plates, the pressure of the operating pressure can be borne tripartitely, and the dispersion in operation can be restrained by providing some degree of freedom to the design of the individual plates. In this case, as is mentioned earlier, the friction between the contacting surfaces of the snap discs can be reduced by plating the lubricant containing solid molybdenum disulfide thereto.
The second snap disc
5
is supported by the snap disc receiver provided to the upper surface of the second sliding member
6
, and the peripheral rim thereof is stopped against the inner surface of the outer peripheral wall
5
a.
The second snap disc portion
5
functions to sense high pressure cut off pressure PH and PH−DELTA PH.
The second sliding member
6
includes the snap disc receiver and the outer peripheral wall
5
a
surrounding the same to the upper surface thereof, a central axis hole
28
concentric to the hole H to the central portion thereof, and a central projection
25
projecting from the periphery of the central axis hole
28
to the lower surface thereof. The peripheral rim of the second snap disc portion
5
is stored inside the snap disc receiver at the upper surface of the second sliding member
6
, and the periphery thereof is stopped against the inner surface of the outer peripheral wall
5
a
. The outer periphery of the second sliding member
6
slides directly against the inner wall of the switch case
2
. The central axis hole
28
is of a diameter larger than that of the central axis hole
27
of the first sliding member
4
, and is pierced by a cylindrical second actuating rod
24
having subst
Koguchi Masayuki
Naganuma Shingo
Enad Elvin
Fujikoki Corporation
Klaus Lisa N
Rader & Fishman & Grauer, PLLC
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