U.S. patent number 3,764,763 [Application Number 05/218,718] was granted by the patent office on 1973-10-09 for pressure switch.
This patent grant is currently assigned to Eaton Corporation. Invention is credited to Gene A. Barnes.
United States Patent |
3,764,763 |
Barnes |
October 9, 1973 |
PRESSURE SWITCH
Abstract
A pressure switch simple to construct, accurate over a very wide
range and easily adjustable to provide various combinations of high
and low levels comprises a housing, a pressure chamber, a switch
blade means movable between contact with first and second movable
contact means and a contact stop means having first, second and
third camming means controlling respectively the first and second
contact means and the switch blade means. The camming means may
each be a pair of spaced opposed surfaces in the contact stop means
whereby movement of the contact stop means controls the positions
of the switch blade means and a movable contact means so that
various levels of fluids may be controlled by the pressure
switch.
Inventors: |
Barnes; Gene A. (Skokie,
IL) |
Assignee: |
Eaton Corporation (Cleveland,
OH)
|
Family
ID: |
22816220 |
Appl.
No.: |
05/218,718 |
Filed: |
January 18, 1972 |
Current U.S.
Class: |
200/83SA;
200/83WM |
Current CPC
Class: |
H01H
35/2614 (20130101); H01H 35/265 (20130101) |
Current International
Class: |
H01H
35/24 (20060101); H01H 35/26 (20060101); H01h
001/48 () |
Field of
Search: |
;200/83WM,83S,83SA,81.4,81.5 ;337/311,323,361,330 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schaefer; Robert K.
Assistant Examiner: Smith; William J.
Claims
I claim:
1. In an electrical switch means having a switch blade means
movable between electrical contact with a first and second movable
contact means, the improvement comprising a contact stop means
including a first camming means controlling said first movable
contact means, a second camming means controlling said second
movable contact means, a third camming means controlling the
position of said switch blade means relative to said first and
second movable contact means, said camming means being coaxial, and
a common actuator therefor to effect a variation in the point of
contact between said switch blade means relative to said first and
second movable contact means.
2. A switch means according to claim 1 wherein said first, second
and third camming means are each a pair of spaced, opposed annular
surfaces on said contact stop means whereby movement of said cam
stop means controls the position of said switch blade means and
said movable contact means.
3. A switch means according to claim 2 wherein said opposed
surfaces of said first camming means receive a portion of said
first contact means therein, said opposed surfaces of said second
camming means receiving a portion of said second movable contact
means therein, said opposed surfaces of said third camming means
receiving a portion of said switch blade means therein, said
opposed surfaces of said camming means each being spaced apart a
distance to allow movement of the portion of the respective contact
means and switch blade means received therein within predetermined
limits.
4. A switch means according to claim 3 wherein said opposed
surfaces of said first and second camming means are generally
parallel to each other whereby a constant differential reset level
relationship is produced.
5. A switch means according to claim 1 wherein said switch blade
means is connected with a pressure responsive means whereby
pressure changes may cause movement of said switch blade means in
generally opposite first and second directions, a resilient biasing
means connected with said switch blade means to oppose movement of
said switch blade means by said pressure responsive means in said
first direction and to assist movement of said switch blade means
in said second direction.
6. A switch means according to claim 5 wherein the force exerted by
said resilient biasing means may be adjusted to vary the amount of
pressure necessary to cause movement of said pressure responsive
means.
7. A switch means according to claim 5 wherein said pressure
responsive means is a diaphragm which bounds a pressure chamber,
said pressure chamber being adapted to be operatively connected to
a variable pressure source, said diaphragm being a polyurethane
film.
8. A switch means according to claim 3 wherein said opposed
surfaces of said camming means are spaced apart a distance to allow
movement of said first and second contact means, said first and
second contact means being biased toward said switch blade means,
said contacts between said switch blade and said contact means
being arranged so that said switch blade means overcomes the bias
of the contact means it is engaging and moves said contact means
from one opposite surface of its respective cam means to the other
opposite surface.
9. A switch means according to claim 1 wherein the contact means
and the switch blade means are positioned relative to each other at
an effective angle of inclination, said effective angles of
inclination being variable by said camming means on said contact
stop means whereby the amount of wipe of the contacts may be
varied.
10. A switch means according to claim 1 wherein said first and
second movable contact means and said switch blade means each have
protruding contact points thereon, said contact points providing
the points of engagement of the switch blade means with the
respective contact means whereby the opposing forces in the switch
blade means and in the contact means are transmitted directly
through the contact points.
11. In an electrical switch means having switch blade means movable
between electrical contact with a first and second movable contact
means, the improvement comprising a contact stop means in the form
of a generally cylindrical rotatable member, having a first camming
means extending thereabout controlling said first movable contact
means, a second camming means spaced from said first camming means
for controlling said second movable contact means, and a third
camming means controlling the position of said switch blade means
relative to said first and second movable contact means, said
first, second and third camming means each comprising a pair of
spaced opposed camming surfaces extending about said cylindrical
shaped rotatable member and forming first, second and third camming
grooves, said first groove receiving a portion of said first
contact means therein, said second groove receiving a portion of
said second movable contact means therein, and said third groove
receiving a portion of said switch blade means therein, for varying
the positions of said movable contact means and said switch blade
means relative to each other upon turning movement of said
cylindrical member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to fluid pressure responsive
circuit makers and breakers and more particularly concerns a fluid
pressure switch having a diaphragm which is moved by the fluid
pressure to actuate a switch blade means movable between contact
with first and second electrically connected contact means. The
switch blade and contacts are easily movable by a contact stop
means to adjust their position relative to each other so that the
pressure necessary to cause actuation thereof may be varied.
2. Prior Art
The use of pressure switches to be responsive to functions of
pressure such as controlling the level of fluid in a receptacle is
old and well known. It is also known to provide a means for
automatically controlling the level of fluid between an upper and
lower level in relationships which are known, as for example, the
constant reset level relationship, the constant differential reset
level relationship, and the proportional reset level
relationship.
In what is known as the "constant reset level", the relationship of
the upper and lower levels is such that the lower level of the
fluid or pressure remains constant while the upper level of the
fluid or pressure is varied. The "constant differential reset
level" indicates the relationship wherein the difference between
the high and low pressure or fluid levels remains constant so that
as the upper level is increased or decreased, the lower level
remains at a predetermined constant differential therefrom. With
the "proportionate reset level" an increase or decrease in the
upper fluid or pressure level causes a proportionate increase or
decrease in the lower fluid or pressure level so that, for example,
as the upper level increases, the difference between it and the
lower level increases proportionately.
According to the prior art these various pressure or level
relationships may not be produced by a single basic pressure switch
structure, but rather require extensive modifications of a basic
assembly to produce what in effect are separate switch structures.
Moreover, with the prior art constructions, it is not possible to
provide a combination of these different level relationships in a
single pressure switch structure.
A particularly advantageous use of the invention herein occurs in
automatic clothes washing machines wherein it is desirable that a
wide range of fluid levels be easily and accurately maintained by
as small, as economical and as fool-proof a switch structure as is
possible. In recent years these machines have increased in size and
hence it is becoming more important that the water level in the
machines be controllable over a wider range of enable these higher
capacity machines to carry a wide range of loads. Thus, for
example, it is no longer unusual for the water level selections to
vary from four inches for a light load to 18 or more inches for a
heavy load. Compounding these requirements is a greater emphasis on
a higher degree of accuracy, stability, consistency of performance,
and a desire for a smaller size pressure switch. Moreover, the
higher motor requirement have increased the electrical load thereby
increasing the effects of contact chatter, contact bounce and
subsequent contact welding.
The above noted deficiencies in the prior art are by way of example
and are only representative of problems being encountered in the
development of pressure responsive switch means which can meet the
requirements of todays rapidly expanding technology.
SUMMARY OF THE INVENTION
The many problems of the prior art are overcome by the pressure
responsive switch means according to the invention herein in which
an easily positionable contact stop means cooperates with a switch
blade means movable between contact with a first and second contact
means to move the switch blade means and the first and second
contact means relative to one another and to limit their extent of
movement so that the amount of pressure and hence the fluid level
to which the switch means will be responsive to may be simply and
accurately varied. The switch means further includes a pressure
chamber bounded in part by a diaphragm means with the pressure
chamber being adapted to be connected to a variable pressure
source. The switch blade means is operatively connected to the
diaphragm means and the switch blade means has connected therewith
a variable biasing means to vary the force required to move the
switch blade means whereby the switch blade means may be movable
against the force of the biasing means from the first contact means
to the second contact means.
The first, second and third camming means are each a pair of spaced
opposed surfaces receiving therebetween a portion of the first
contact means, the second contact means and a switch blade means,
respectively, so that movement of the cam stop means controls the
position of the switch blade means and the movable contact means.
The opposed surfaces of the camming means are each spaced apart a
distance to allow movement of the portion of the respective contact
means and switch blade means received therein within predetermined
limits. The first and second contact means may be biased toward
each other and toward intermediate switch blade means and will lie
adjacent the innersurface of the first and second camming means
respectivley so that it may move between the opposed camming
surfaces in response to contact by the switch blade means whereby
the rapid movement of the switch blade means may be brought to a
stop with the contact means against the outer camming surface and
in abutment with the switch blade means. The controlled movement of
the contact means between the inner and outer surfaces of its
respective cam means greatly reduces any tendency for the contacts
to bounce or chatter. By varying the angle of the arm of the
contact means with respect to the switch blade means, any amount of
wiping of the contacts can be obtained. The control of amount of
wiping of the contacts is important in that it allows the
generation of a force multiplication which will break any contact
welds which may have been formed between the contacts.
To produce a constant differential reset level relationship between
the upper and lower fluid levels the opposed surfaces of the first
and second camming means are arranged generally parallel to each
other so that the difference between the high and low pressure of
fluid levels remains constant. To produce a constant reset level
relationship the opposed surfaces of the second camming means are
arranged so that upon movement of the contact stop means the second
contact means remains generally in its original position whereas
the first camming means diverges therefrom as required to produce a
predetermined upper level. With the proportionate reset level the
first and second camming means are divergent in a proportional
relationship to the movement of the contact stop so that, for
example, as the upper level increases, the difference between it
and the lower level increases proportionately. In addition to being
able to control these basic relationships it may be seen that the
first, second an third camming means may be varied to produce
practically all relationships or combinations thereof. Moreover, it
will be understood by those skilled in the art that the pressure
switch housing according to the invention herein may be quickly
snapped open and a new and/or different contact stop means readily
inserted to allow this very wide range of operation.
The unique features of the pressure responsive switch according to
the invention may be seen in the fact that the switch speed is a
function of diaphragm speed which will cause the switch making to
be bounced free due to a slow speed. Also, the arc generation due
to breaking contacts is minimized by being able to control the
speed of opening of the contacts whereas a conventional switch will
break at a great enough speed to cause high arc generation. The
camming means on the contact stop means provide positive stops for
the contact means as well as the switch blade means for each of an
almost infinite variety of positions. This thereby allows ready
control of the diaphragm stroke and the curve in a graph of force
on the switch blade means versus stroke of the switch blade means
is greatly improved by being able to select just the portion of the
curve required for each situation. Furthermore, these stops
provided by the camming means drastically improve the ease of
analysis and design of the switch to meet a desired condition.
Still further the fact that all of the forces are directly
transmitted through the contact points produces very high contact
forces and hence allows greater electrical power and avoids chatter
and other problems associated with the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the invention will be
readily apparent from the following description of certain
preferred embodiments thereof, taken in conjunction with the
accompanying drawings although variations and modifications may be
effected without departing from the spirit and scope of the novel
concepts of the disclosure and in which:
FIG. 1 is a schematic cross sectional diagram of the invention as
embodied in a typical washing machine water system;
FIG. 2 is a schematic cross sectional elevation of an embodiment in
a pressure responsive switch means adapted to be used in the system
of FIG. 1;
FIG. 3 is an isolated view of the contact stop means of FIG. 2 with
the switch blade means shown in the normally opened position as
opposed to the normally closed position of FIG. 2;
FIG. 4 is an isolated view of another embodiment of a contact stop
means configured to provide a generally constant differential reset
level relationship;
FIG. 5 is a graph of force versus stroke of the switch blade means
indicating the ability to select a desired portion of the curve
between upper and lower levels;
FIG. 6 is a graph of water level versus adjustment and indicates
the ability of the pressure responsive switch means of the
invention to provide various fluid level relationships;
FIG. 7 is another graph of water level or pressure versus
adjustment which serves to indicate the examples of the
combinations of fluid level relationships which may be obtained
with the invention herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the schematic diagram of a typical wash machine water
system in FIG. 1 there may be seen a pressure responsive switch
means 10 according to the invention having an inlet 12 in
communication with a pressure conduit 14 which in turn is in
pressure communication with a wash machine tube 20. A pressurized
water supply schematically represented by the conduit 22 is opened
and closed by a solenoid water valve 24 which in turn is connected
by suitable electrical connection means 26 to the pressure switch
10 whereby the solenoid water valve is controlled by the pressure
switch 10. When the water valve 24 is opened water runs into the
tub 20 through the conduit 23 to fill the tub to a desired water
level. The tub 20 may include the conventional drain means 30 and
pump 32 for draining the wash water.
The depth of water or range of levels of water in the tub 20 is
indicated by the arrow 36 extending between the bottom of the tub
20 and the desired upper water level 37. It is important in a wash
machine to control the level of water at two points, the first is
the desired water level 37 at which point the water is cycled or
"tripped" off after filling the tub 20 and the second point is the
lower water level limit indicated at 38 at which point the switch
is "reset" and the water is cycled on. By means of the invention
herein both the desired upper water level 37 and the lower water
limit 38 may be easily and conveniently regulated to have the
relationships of levels 37 and 38 known as "constant differential",
a "proportional differential" or "constant reset". It is also
unique to this invention that variations of these combinations may
be possible. These relationships will be explained in greater
detail with regard to the operation of the invention.
With the demands for washing machines having increased capacity, it
has become more important to be able to control the water level 36
in the tub 20 over a wider range since a machine of high capacity
must still be able to handle a minimum load. For example,
variations in the water level 36 from 4 inches for a light load to
eighteen or more inches for a heavy load are no longer unusual. In
addition to this requirement a greater emphasis is being placed on
the accuracy and consistency of the water levels. Compounding these
requirements is the desire for a pressure switch of minimum size
which may be easily accommodated in the machine cabinet.
All of the above noted requirements and more are met by the
pressure responsive switch means 10 of the invention.
Referring to FIG. 2 there is shown an enlarged cross sectional view
of the pressure switch 10 embodying the instant invention.
Essentially the pressure switch 10 comprises an expandable air
chamber 15 communicating at one portion thereof with the conduit 14
and having a diaphragm means 16 bounding another portion thereof. A
diaphragm means 16 is connected by a translation member 17 to an
elongated blade-like switch plate means 40 so that movements of the
diaphragm 16 in response to pressure changes in the pressure
chamber 15 are transferred to the switch blade means 40 by the
translation member 17. A first contact means 50 is positioned on
one side at an angle to the switch blade means 40. The first
contact means 50 includes a contact 52. A second contact means is
situated on an opposite side of the switch blade means 40 and also
extends at an angle thereto. The second contact means includes a
contact 62. Both the contact means 50 and 60 may comprise flexible,
elongated blade members. The contact means 50, the contact means 60
and the switch blade means 40 each have portions engaging
respectively a first camming means 55, a second camming means 65
and a third camming means 45 which camming means are located on a
contact stop means 70 and control the permissible movement of the
respective contact means and switch blade. As shown, the contact
stop means 70 may be rotatably mounted in a housing 11 of the
pressure switch means 10.
A tension spring 80 has a first end 81 attached to the switch blade
means 40 and a second end 82 attached to an adjustment means 85
whereby the tension in the spring means 80 may be varied. The
resilient tension force in the spring 80 acts against the force
transmitted through the translation member 17 by an increasing
pressure in the pressure chamber 15. Thus, the increasing force on
a diaphragm 16 as transmitted by the translation means 17 is
opposed by the tension means 80 until the force on the translation
member 17 overcomes the tension force on the spring means 80 at
which point the switch blade means 40 is moved from its normally
closed position as shown in FIG. 2 to a normally opened position as
illustrated in FIG. 3. Each of the means 40, 50 and 60 includes
electrically conductive means so that the switching of the switch
blade 40 between the first contact means 50 and the second contact
means 60 breaks one circuit and makes another in response to the
change in pressure in the pressure chamber 15. It will be
understood that generally, the pressure switch means 10 acts as a
transducer, converting a hydropneumatic function into an electrical
function. That is, the increase in the level 36 of water in the tub
20 as shown in FIG. 1, causes a column of water to rise in the
conduit 14 compressing the air in the upper end thereof, which air
acts on a pressure chamber diaphragm 16 and the pressure switch 10
to move the diaphragm 16 in relation to the pressure and thereby
open and close electrical circuits of which the switch blade means
40 and the first and second contact means 50, 60, form a part of.
As the water depth 36 reaches a water level 37 determined primarily
by the position of the first camming means 55 and the third camming
means 45 on the contact stop means 70, an air pressure head in the
chamber 15 causes the diaphragm means 16 to overcome a
predetermined tension in the spring means 80 to thereby move the
contact arm 40 from the normally closed contact 50 which is part of
a circuit that will activate the solenoid 24 to allow water under
pressure in the pipe 22 to be dispensed into the tub 20 through the
inlet 23 and move it to the normally closed contact means 60
thereby stopping further flow of water into the tub 20 and to
activate the circuit of which contact means 60 may be a part. As
the water level decreases and the consequent pressure in the
chamber 15 decreases the diaphragm 16 will be moved in a direction
whereby the contact between the switch blade 40 and the second
contact means 60 is broken and the contact between the switch blade
means 40 and the contact means 50 is made to thereby activate the
solenoid 24 and again increase the water level in the tub 20 to the
desired selected level 37 at which point the cycle is repeated.
The first, second and third camming means 55, 65 and 45,
respectively, each comprise a pair of opposed inner and outer
surfaces 56, 57; 66, 67; and 46, and 47. Each of the respective
camming means 55, 65 and 45 receive between their respective inner
and outer surfaces a portion of the respective first camming means
50a, the second camming means 60a and the switch blade means 40a.
With such arrangement the movement of the cam stop means 70
controls the relative positions of the switch blade means 50, 60
and the movable contact means 40. The opposed surfaces of the
camming means are each spaced apart a distance to allow movement of
the portion of their respective contact means and switch blade
means received therein within predetermined limits. As shown in
FIGS. 2, 3 and 4 the contact stop means may take the form of a
generally cylindrically shaped rotatable member wherein the first
camming means takes the form of a groove means on the outer surface
of the generally cylindrically shaped member and receives the
portion 50a of the first contact means therein. Similarly, the
second camming means 65 will be a groove on the outer generally
cylindrically shaped surface of the contact stop means 70 and
receives a portion 60a of the second movable contact means therein.
The third camming means 45 also is a groove means on a generally
cylindrically shaped surface of the contact stop means 70 and
receives a portion 40a of the switch blade means therein.
Accordingly, it may be seen that as the contact stop means 70 is
rotated by means of a portion 70a projecting beyond the housing 11,
the position of the first contact means 50 will vary in relation to
the generally constant position of the second contact means 60.
This variation in the location of the first contact means 50 has
the effect of changing the position of the switch blade means 40
when it is in its normally closed position so that the forces
acting on the switch blade means 40 in opposition to the forces
acting through the translation member 17 will be varied and hence
the "trip" or upper level position 37 of the fluid will be varied.
Suitable gauge and/or indicator means in conjunction with the
contact stop means 70 may be provided to allow selection of the
desired water level in accordance with common and well known
expressions. In the embodiment shown the "lands" 70b and 70c
between the camming means 55, 45 and 65 may be of a width or
configuration in accordance with efficient operation and the sizes
of the contacts 52, 42, and 62, respectively.
The first contact means 50 and the second contact means 60 may be
biased by means not shown toward each other and toward the
intermediate switch blade means 40 to bear against the outer
camming surface 57 and the inner camming surface 66 respectively,
when they are free from contact with the switch blade means 40.
Accordingly, as the switch blade means 40 snaps into contact with
the first contact means 50 it moves the contact means against its
inward biasing force and moves the portion 50a into contact with
the inner camming surface 56 of the first camming means 55. When
the pressure force in the chamber 15 becomes great enough to move
the switch blade means 40 and break contact with the first contact
means 50 the portion 50a of the first contact means 50 returns to
its original position biased against the outer camming surface 57.
At the second contact means 60 the switch blade means 40 moves the
portion 60a from its position biased against the inner camming
surface 66 to a position where it contacts the outer camming
surface 67 as is more clearly shown in FIG. 3. The inward bias of
the contact means 50 and 60 has the effect of decelerating the
switch blade means 40 at the end of its snap-type action movement
and also accelerating the movement of the switch blade means 40 at
the beginning of its movement. This has the effect of reducing if
not eliminating the amount of bounce of the contacts and also
minimizes chatter. Forces between the members 40, 50 and 60 are
transmitted through the contact points 42, 52 and 62 so that an
excellent contact results with accordant improvement of chatter,
capacity and general functioning. The angular relationship of the
contact means 50 and 60 to the switch blade 40 and their different
relative arcuate movement together produces a wiping of the
contacts 42, 52 and 62. This wiping is important in that it allows
the generation of a force multiplication which will break any
contact welds that may have been formed between the contacts while
they were together. This is particularly important with the demands
for higher electrical capacity of these switches. It is another
significant feature of this invention that the angular relationship
of the contact means 50 and 60 with the switch blade means 40 may
be varied to vary the amount of wiping of the contacts. By this
means the wiping may be reduced to zero and the friction present in
the mechanism due to the wiping of the contacts may in theory be
eliminated.
The translation member 17 may be a resilient spring-like member
which will act to store energy during initial movement of the
diaphragm 16 and prior to the diaphragm force overcoming the
resilient spring means 80 so that after the force of the spring
means 80 has been overcome the translation member 17 will tend to
release its energy and effectively snap the switch blade means 40
between the contact means 50 and 60. It will be understood by those
skilled in the art that the resilience of the translation member 17
relative to the spring means 80 and the force on the diaphragm 16
may be designed to vary the movement characteristics of the switch
blade 40. Thus, the translation member 17 may vary from being very
stiff to being very flexible depending upon the switching
characteristics desired. The ease of modification by changing this
one part is yet another example of the flexibility and adaptability
of the switch means of the invention.
By means of the described invention fluid levels may be simply and
accurately varied. A further illustration of the range of
variations which may be effected is the contact stop means 170 in
FIG. 4. Here the first contact means 50 is received in a first
camming means 155, the second contact means 60 is received in a
second camming means 165 and the switch blade means 40 is received
in a third camming means 145. In this case, however, the camming
surfaces 156, 157 of the first camming means 155 and the camming
surface 166 and 167 of the second camming means 165 are parallel to
each other to produce what is known as the constant differential
level wherein the difference between the upper and lower levels
remains constant as they are varied. Other contact stops may be
designed to produce all fluid level relationships which can be
foreseen. Further, the variation and flexibility is readily
effected. For example, by means of lateral protrusions 172 in the
third camming means 45 and 145 respectively, the switch blade means
may be manually urged against the normally closed first contact
means to thereby override the automatic pressure responsiveness.
Clearly, other and different variations will be apparent to those
skilled in the art having knowledge of my invention.
Referring to FIG. 5 there may be seen a graph of force transmitted
to the switch blade member 40 by the translation member 17 versus
the displacement of the switch blade means 40 to illustrate the
ability of the invention herein to allow selection of a particular
portion of a normal toggle curve. Thus, the normal toggle curve is
illustrated at 90, the upper level or "trip" line is indicated at
92, and the reset or lower level is indicated at 94. The line 95
indicates that the pressure will build up on the switch blade means
40 at the normally closed stop until the trip point 96 at the trip
level 92 is reached at which point the switch blade will move and
the force will decrease until the normally opened contact means 60,
in FIG. 2 is reached. At this point the force will again increase
as indicated by the line 97. Effectively the lines 95 and 97
indicate the limits of movement of the switch blade means 40 and
hence allow selection of any portion of the curve 90 as represented
by the portion 98. Moreover, the selection may be simply and
accurately effected.
Referring to FIG. 6 there may be seen a graph of the water level
versus adjustemnt of the contact stop means which will allow the
various relationships of the upper and lower levels. For example,
the constant reset level relationship is illustrated by the lines
100 and 103; the constant differential reset level is illustrated
by the lines 102 and 103; and the proportionate reset level
relationship is illustrated by the lines 101 and 103. In each case
the line 103 represents the trip or upper level and lines 100, 101
and 102 represent the reset or lower level.
In FIG. 7 another example of possible variations in the trip and
reset levels are illustrated by the lines 110 through 117. In this
case lines 110, 111 illustrate one alternate trip level
configuration whereas line 112 represents an alternate trip level.
Similarly, lines 113 through 117 represent individual alternate
variations of relationships. From the foregoing description of the
invention it may be seen that the many problems of the prior art
are overcome by the pressure responsive switch means 10 according
to the invention herein.
Although minor modifications might be suggested by those versed in
the art, it should be understood that I wish to embody within the
scope of the patent warranted hereon all such modifications as
reasonably and properly come within the scope of my contribution to
the art.
* * * * *