BACKGROUND OF THE INVENTION
[0001] The present invention relates to a touch pressure switch including a manually operated
safety switch.
[0002] As is known, in order to measure pressure variations in fluids, there are used the
so-called pressure switches, which include a metal membrane which, in order to provide
a proper tightness, is hot sealed, circumferentially, about the annular edge of a
cap.
[0003] This hot sealing of the metal membrane causes, consequently, variations of the membrane
mechanical properties, with a consequent variation of the resiliency characteristics
thereof, which will cause the operating threshold of the membrane to change.
[0004] Another drawback derives from the fact that the tappet assembly provided for operating
the contacts is also affixed to the membrane by heat sealing operations, which will
cause a further variations of the mechanical characteristics of the assembly with
a further decrease of the accuracy and responsivity speed of the pressure switch.
[0005] Yet another drawback of prior art pressure switches of the above mentioned type,
is that these prior art pressure switches are not flexible in operation, that is they
do not allow to quickly and easily change the operation threshold values, thereby
an user must hold in inventory a great range of pressure switches.
SUMMARY OF THE INVENTION
[0006] Accordingly, the aim of the present invention is to overcome the above mentioned
problems, by providing a touch pressure switch, including a manually operated safety
microswitch, which allows a perfect tightness of the membrane without performing any
hot sealing operations, so as not to undesirably change the resilient characteristics
of the membrane, while providing a very high accuracy and evenness of operation.
[0007] Within the scope of the above mentioned aim, a main object of the present invention
is to provide such a touch pressure switch, in which the driving tappet assembly is
directly formed on the membrane, without using additional elements susceptible to
alter the membrane resiliency.
[0008] Yet another object of the present invention is to provide such a touch pressure switch
the operation threshold values of which can be quickly and simply changed and which,
accordingly, can be used in a very broad range of applications, while providing a
very safe and reliable operation.
[0009] According to one aspect of the present invention, the above mentioned aim and objects,
as well as yet other objects, which will become more apparent hereinafter, are achieved
by a touch pressure switch including a manually operated microswitch, characterized
in that it comprises a bottom body defining a chamber communicating with a fluid to
be controlled, and associated, through a blade or reed contact bearing ring element,
with a top cap, said chamber being closed by a membrane provided with a sealing O-ring
element and connected to a steel membrane, with a driving tappet assembly directly
formed on this latter membrane and operating on a washer element, counterbiassed by
a first counterbiassing spring and affecting at least a blade or reed-like contact,
supported by said contact bearing ring element, a safety manually operated microswitch
being moreover provided which cooperates with a pin element extending from said washer.
DESCRIPTION OF THE DRAWINGS
[0010] Further characteristics and advantages of the present invention will become more
apparent hereinafter from the following detailed disclosure of a preferred, though
not exclusive, embodiment thereof, which is illustrated, by way of an indicative,
but not limitative example, in the figures of the accompanying drawing where:
Figure 1 is an exploded schematic perspective view illustrating the touch pressure
switch, including a manually operated microswitch, according to the present invention;
Figure 2 shows the pressure switch as cross-sectioned along a vertical plane; and
Figure 3 is an elevation side view illustrating the subject pressure switch.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0011] With reference to the number references of the figures of the accompanying drawings,
the touch pressure switch, including a manually operated or re-armed microswitch,
according to the present invention, which has been generally indicated at the reference
number 1, comprises a bottom body 2, which, in its inside, defines a chamber 3 communicating
with an inlet duct 4 in turn connected to a region therein a fluid the pressure of
which is to be controlled is held.
[0012] To the bottom body 2 there is coupled a top cap 5, through the interposition of a
blade or reed contact bearing ring element 6, said cap being restrained, with respect
to said bottom body 2, by means of an outer metal edged portion 7.
[0013] More specifically, the chamber 3 is closed by a rubber membrane 10 which is provided,
on its periphery, with an O-ring element 11 providing fluid tightness. The rubber
or silicone rubber membrane 10, is coupled to a metal membrane 12, in particular a
stainless steel membrane, which is held in its set position by means of a safe ring
element 13, arranged between the reed contact bearing ring element 6 and said membrane,
so as to provide a perimetrical clamping force.
[0014] That same safety ring element 13, moreover, will prevent the membrane 12 from being
deformed or broken, as the pressure switch must be adjusted by operating the dowel
element 32.
[0015] As shown, the metal membrane 12 is provided, at a central portion thereof, with a
driving tappet assembly 15, which is directly provided as a single piece with said
membrane 12, for example by means of mechanical pressing operations, and axially operates
on or affects a washer element 20 which is slidably guided inside the cap 5.
[0016] As further shown, the washer element 20 is pushed or counterbiassed by a first counterbiassing
spring 21, operating between said washer element and an adjusting screw 22, which
latter rotatably engages in a threaded hole 23 formed in the cap.
[0017] Moreover, a stem element 25 is provided, extending from the washer element and engaging
in a guide hole 26, axially formed through said adjusting screw 22, and between this
adjusting screw and the spring 21 a sliding element 27 is interposed.
[0018] The washer element 20 operates on the reed contacts 30 provided on the contact bearing
discs 6 (see figures 1 and 2) and which has a C-shape configuration, therefrom a fixed
contact 31 projects, which projects outwardly from the cap, whereas on the two resiliently
movable arms 30a and 30b operate pin elements 35 provided on the washer 20 and engaging
with said contacts.
[0019] In this connection it should be apparent that by changing the operation point of
the pin elements 35 on the contacts 30a and 30b, it will be possible to obtain a different
displacement degree of the reed contacts, with a consequent possibility of reversing
these contacts.
[0020] More specifically, the reed contacts are cut to a desired shape about a contact pad,
so as to provide the reed element with a desired flexibility property, at the push
point, and, moreover, they can be moved towards one another by means of screws.
[0021] As shown, the reed contacts 30a and 30b cooperate with respective fixed contacts,
indicated at the reference number 36, which connect with outer fixed contacts 37 projecting
from the cap.
[0022] A safety microswitch, indicated at 40, is moreover provided, preferably of the manually
operated or rearmed type, which is coupled to the cap by means of a supporting plate
41 made for example of ryton, and being provided with a small lever 42 operating on
the push-button 43 of the microswitch, and with which a pin element 44 engages which
is connected to the washer.
[0023] Also in this case, it. is possible to obtain a broad adjusting range, that is a broad
operation threshold range, for the safety microswitch, which can be obtained by providing
a slot through the small plate allowing a clockwise displacement or, if desired, this
can be obtained by changing the operating position by means of a screw provided with
a related counterbiassing spring.
[0024] It should moreover be pointed out that it is also possible to provide, on the manually
operated or re-armed element, resilient counterbiassing springs, allowing to easily
and quickly change the operating force exerted on the manually operated lever, as
well as on the driving lever 42.
[0025] The above disclosed arrangement allows to adjust at will, within very broad ranges,
all of the pressure switch operating threshold values, by operating the adjusting
screws 22 affecting the position of the reed contacts and that of the driving pin
elements.
[0026] Moreover it is further possible to provide a second counterbiassing spring, directly
operating on the rubber membrane which can be arranged at the point indicated at 3.
[0027] From the above disclosure it should be apparent that the invention fully achieves
the intended aim and objects.
[0028] In particular the fact is to be pointed out that a touch pressure switch construction
has been provided, including a safety microswitch, which allows a perfect tightness
to the fluid to be controlled, without using heat sealing operations and which, moreover,
allows to change within very broad ranges, all of the calibrating values.
[0029] Obviously, the subject pressure switch can be also provided with a working or operating
microswitch.
[0030] In practicing the invention, the used materials, provided that they are compatible
to the intended use, as well as the contingent size and shapes can be any according
to requirements.
1. A touch pressure switch including a manually operated microswitch, characterized in
that it comprises a bottom body defining a chamber communicating with a fluid to be
controlled, and associated, through a blade or reed contact bearing ring element,
with a top cap, said chamber being closed by a membrane provided with a sealing O-ring
element and connected to a steel membrane, with a driving tappet assembly directly
formed on this latter membrane and operating on a washer element, counterbiassed by
a first counterbiassing spring and aftecting at least a blade or reed-like contact,
supported by said contact bearing ring element, a safety manually operated microswitch
being moreover provided which cooperates with a pin element extending from said washer.
2. A pressure switch, according to Claim 1, characterized in that said switch comprises
a safety ring element arranged between said blade or reed contact bearing ring element
and the periphery of said steel membrane, in order to peripherally restrain said steel
membrane.
3. A pressure switch, according to Claims 1 and 2, characterized in that said O-ring
sealing element is formed as a single piece with said membrane.
4. A pressure switch, according to one or more of the preceding claims, characterized
in that said contact bearing ring element supports a reed contact having a substantially
C-shape, and provided with a fixed contact which projects outwardly and is connected
to an intermediate portion of said reed contact elements.
5. A pressure switch, according to one or more of the preceding claims, characterized
in that it further comprises pin elements projecting from said washers and adapted
to operate with a preset portion of the resiliently movable arms of said reed contact
elements.
6. A pressure switch, according to one or more of the preceding claims, characterized
in that the contact point of a said pin element on said reed contact elements can
be changed in order to change the displacement of the reed contact elements.
7. A pressure switch, according to one or more of the preceding claims, characterized
in that said reed contact element is cut to a set shape about a contact pad, in order
to provide the reed with a set flexibility at its pushing point.
8. A pressure switch, according to one or more of the preceding claims, characterized
in that it further comprises, at said reed contact elements, fixed contact elements
connected to further contacts projecting from said cap.
9. A pressure switch, according to one or more of the preceding claims, characterized
in that said safety microswitch of the manually operated or re-armed type is a working
type of microswitch.
10. A pressure switch, according to one or more of the preceding claims, characterized
in that said safety microswitch is supported by a ryton plate connected by means of
screws to said cap.
11. A pressure switch, according to one or more of the preceding claims, characterized
in that said microswitch can be adjusted, by adjusting said plate through an angular
displacement, which can be obtained by providing a slot through said plate, for a
clockwise displacement, or by means of a screw, provided with a counterbiassing spring
or other equivalent element.
12. A pressure switch, according to one or more of the preceding claims, characterized
in that the first counterbiassing or reaction spring operates on an adjusting screw,
engaging in a threaded hole formed in said cap.
13. A pressure switch, according to one or more of the preceding claims, characterized
in that it comprises a sliding element arranged between the first reaction or counterbiassing
spring and the end of the adjusting screw.
14. A pressure switch, according to one or more of the preceding claims, characterized
in that it further comprises a second reaction or counterbiassing spring, operating
on the O-ring element membrane.
15. A pressure switch, according to one or more of the preceding claims, characterized
in that said safety microswitch, of the manually re-armed or operated type, is provided
with resilient means for adjusting the trip arm of said safety microswitch.