Multiple contact fluid pressure switch

Information

  • Patent Grant
  • 6639165
  • Patent Number
    6,639,165
  • Date Filed
    Monday, October 28, 2002
    22 years ago
  • Date Issued
    Tuesday, October 28, 2003
    21 years ago
Abstract
A multiple contact fluid pressure switch includes a plate from which a rib extends to establish a cavity on the plate. Two lower contacts are on the plate within the cavity. A diaphragm is disposed on the rib to enclose the cavity. Further, an upper contact is disposed on the diaphragm directly above the lower contacts. The multiple contact fluid pressure switch is movable between an open position wherein the upper contact does not engage the lower contacts, a first closed position wherein the upper contact engages one lower contact, and a second closed position wherein the upper contact engages both lower contacts.
Description




TECHNICAL FIELD




The present invention relates generally to fluid pressure switches.




BACKGROUND OF THE INVENTION




Tire pressure sensors are standard equipment on many vehicles manufactured today. The tire pressure sensors can alert drivers when the tire air pressure becomes dangerously low and avert the likelihood of an accident caused by low tire pressure.




Typical pressure measurement sensors use a piezo-resistive silicon-based pressure sensing element for measuring fluid pressure. Unfortunately, these sensors can consume a considerable amount of current from sources used to power them. For some applications, e.g., tire pressure sensing, a very small battery is used as the power source and the life of the battery is a very important design factor. As recognized herein, by using a pressure activated switch, the sensor circuitry can be modified to minimize the amount of current required to operate the sensor and thus, reduce the electronic overhead of the sensor. With fewer required components, manufacturing costs are reduced.




It happens that fluid pressure activated switches are available. However, since these switches only include a single trip point and are actuated at only a single pressure value, a single fluid pressure activated switch cannot be used to report multiple pressure values in a system.




The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.




SUMMARY OF THE INVENTION




A multiple contact fluid pressure switch includes a plate. A rib extends from the plate to establish a cavity on the plate. Two lower contacts are installed in the cavity. A diaphragm encloses the cavity. An upper contact is disposed on the diaphragm. The multiple contact fluid pressure switch is movable between an open position wherein the upper contact does not engage the lower contacts, a first closed position wherein the upper contact engages only one lower contact, and a second closed position wherein the upper contact engages both lower contacts. In a preferred embodiment, the diaphragm is disposed on the rib.




In one aspect of the present invention, a central rib extends from the plate and divides the cavity into a first cavity and a second cavity. A first lower contact is disposed within the first cavity and a second lower contact is disposed within the second cavity. Moreover, the diaphragm is a first diaphragm that encloses the first cavity and the second cavity, and the switch further includes a second diaphragm that is affixed to the first diaphragm. The second diaphragm spans the area above the second cavity. In this aspect of the present invention, the switch includes a first upper contact that is affixed to the first diaphragm above the first lower contact and a second upper contact that is affixed to the first diaphragm above the second lower contact. The switch is movable between an open position wherein the upper contacts do not engage the lower contacts, a first closed position wherein the first upper contact engages the first lower contact, and a second closed position wherein the first upper contact continues to engage the first lower contact and wherein the second upper contact engages the second lower contact.




In yet another aspect of the present invention, the multiple contact fluid pressure switch includes a central lower contact and a first outer lower contact spaced from the central lower contact. Moreover, the upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the first outer lower contact. In this aspect, the switch further includes a second outer lower contact placed below the common upper contact. The switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least one of the outer lower contacts.




In still another aspect of the present invention, the multiple contact fluid pressure switch includes a central lower contact and an outer lower contact spaced from the central lower contact and surrounding the central lower contact. The upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the outer lower contact. In this aspect, the multiple contact fluid pressure switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least a portion of the outer lower contact.




In yet still another aspect of the present invention, a fluid pressure switch includes a cavity. Two lower contacts are disposed within the cavity. A diaphragm encloses the cavity. An upper contact is disposed on the diaphragm above the lower contacts. In this aspect, the fluid pressure switch is movable between an open position wherein the upper contact does not engage the lower contacts, a first closed position wherein the upper contact engages one lower contact, and a second closed position wherein the upper contact engages both lower contacts.




The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a cross-section view of a multiple contact fluid pressure switch in the open position;





FIG. 2

is a cross-section view of the multiple contact fluid pressure switch in the first closed position;





FIG. 3

is a cross-section view of a multiple contact fluid pressure switch in the second closed position;





FIG. 4

is a top plan view of the multiple contact fluid pressure switch with the diaphragm and upper contacts removed for clarity;





FIG. 5

is a cross-section view of a first alternative multiple contact fluid pressure switch in the open position;





FIG. 6

is a cross-section view of the first alternative multiple contact fluid pressure switch in the first closed position;





FIG. 7

is a cross-section view of the first alternative multiple contact fluid pressure switch in the second closed position;





FIG. 8

is a top plan view of the first alternative multiple contact fluid pressure switch with the diaphragm and common contact removed for clarity;





FIG. 9

is a cross-section view of a second alternative multiple contact fluid pressure switch in the open position;





FIG. 10

is a cross-section view of the second alternative multiple contact fluid pressure switch in the first closed position;





FIG. 11

is a cross-section view of a the second alternative multiple contact fluid pressure switch in the second closed position; and





FIG. 12

is a top plan view of the second alternative multiple contact fluid pressure switch with the diaphragm and common contact removed for clarity.











DESCRIPTION OF AN EMBODIMENT OF THE INVENTION




Referring initially to

FIGS. 1-4

, a multiple contact fluid pressure switch is shown and generally designated


10


. In a preferred embodiment, the multiple contact fluid pressure switch


10


is manufactured using micro-electro-mechanical systems (MEMS) technology which offers the most reliable method for building the multiple contact fluid pressure switch


10


, described in detail below.





FIGS. 1-4

show that the multiple contact fluid pressure switch


10


includes a preferably glass, flat, rectilinear plate


12


having a peripheral rib


14


extending from the upper surface of the plate


12


around the outer periphery of the upper surface. A central rib


16


extends from one side of the peripheral rib


14


to the opposite side of the peripheral rib


14


to establish a first cavity


18


and second cavity


20


above the plate


12


within the confines of the peripheral rib


14


.




As shown in

FIGS. 1-4

, a preferably gold first lower contact


22


is affixed to the upper surface of the plate


12


within the first cavity


18


and extends from within the first cavity


18


through the peripheral rib


14


. Also, a preferably gold second lower contact


24


is affixed to the upper surface of the plate


12


within the second cavity


20


and extends from within the second cavity


20


through the peripheral rib


14


.





FIGS. 1-3

show that a preferably resilient, first diaphragm


26


is disposed on top of the peripheral rib


14


and the central rib


16


so that it completely encloses the first cavity


18


and the second cavity


20


. In a preferred embodiment, the cavities


18


,


20


are airtight. Moreover, a first upper contact


28


is attached to the interior surface of the diaphragm directly above the first lower contact


22


. Also, a second upper contact


30


is attached to the interior surface of the first diaphragm


26


above the second lower contact


24


so that it can engage the second lower contact, as described below.

FIGS. 1-3

also show that in a preferred embodiment, a preferably resilient, second diaphragm


32


is installed over a portion of the first diaphragm


26


, specifically over the second cavity


20


. This effectively increases the thickness of diaphragm material over the cavity and as described below, increases the pressure required to engage the second upper contact


30


with the second lower contact


24


.




It is to be understood that as the external pressure increases, the multiple contact fluid pressure switch


10


moves between an open position shown in

FIG. 1

, a first closed position shown in

FIG. 2

, and a second closed position shown in FIG.


3


. Specifically, as the pressure overcomes the stiffness of the first diaphragm


26


over the first cavity


18


the first diaphragm


26


is pushed into the first cavity


18


until the first upper contact


28


engages the first lower contact


22


such that the multiple contact fluid pressure switch


10


is in the first closed position. Moreover, as the pressure continues to increase and overcomes the combined stiffness of the first diaphragm


26


and the second diaphragm


32


over the second cavity


20


, the first diaphragm


26


and the second diaphragm


32


are pushed into the second cavity


20


until the second upper contact


30


engages the second lower contact


24


such that the multiple contact fluid pressure switch


10


is in the second closed position.




According to the present invention, the multiple contact fluid pressure switch


10


can be installed in a pressurized environment, e.g., a tire. Accordingly, as the pressure decreases in the tire, e.g., due to a hole in the tire, the second upper contact


30


will disengage the second lower contact


24


and open a circuit causing a warning to be sent to a driver. As the pressure continues to decrease, the first upper contact


28


will disengage the first lower contact and open another circuit causing a second warning to be sent to the driver. Accordingly, it can be appreciated that the multiple contact fluid pressure switch


10


detects decreasing fluid pressure in addition to increasing fluid pressure. It is to be understood that the multiple contact fluid pressure switch


10


can have more than two cavities and with each additional cavity the overall diaphragm thickness above each additional cavity is increased incrementally. Further, the multiple contact fluid pressure switch


10


, e.g., the contacts


22


,


24


,


28


,


30


can be integrated with an application specific integrated circuit (ASIC).




Referring to

FIGS. 5-8

, an alternative multiple contact fluid pressure switch is shown and generally designated


50


.

FIGS. 5-8

show that the multiple contact fluid pressure switch


50


includes a preferably glass, flat, rectilinear plate


52


having a peripheral rib


54


extending from the upper surface of the plate


52


around the outer periphery of the upper surface to establish a cavity


56


above the plate


52


within the confines of the peripheral rib


54


.




As shown in

FIGS. 5-8

, a preferably gold central lower contact


58


is affixed to the upper surface of the plate


52


within the cavity


56


and extends from within the cavity


56


through the peripheral rib


54


. Also, a preferably gold first outer lower contact


60


and second outer lower contact


62


are affixed to the upper surface of the plate


52


within the cavity


56


such that they flank the central lower contact


58


. As shown, the outer lower contacts


60


,


62


also extend from within the cavity


56


through the peripheral rib


54


.





FIGS. 5-7

show that a diaphragm


64


is disposed on top of the peripheral rib


54


so that it completely encloses the cavity


56


. Preferably, the cavity


56


is airtight. As shown, a preferably gold, flexible common upper contact


66


is attached to the interior surface of the diaphragm


64


directly above the central lower contact


58


and the outer lower contacts


60


,


62


. As described below, the common upper contact


66


can engage the central lower contact


58


and the outer lower contacts


60


,


62


.




It is to be understood that as the external pressure increases, the multiple contact fluid pressure switch


50


moves between an open position shown in

FIG. 5

, a first closed position shown in

FIG. 6

, and a second closed position shown in FIG.


7


. Specifically, as the pressure overcomes the stiffness of the diaphragm


64


over the cavity


56


the diaphragm


64


is partially pushed into the cavity


56


until the common upper contact


66


engages the central lower contact


58


such that the multiple contact fluid pressure switch


50


is in the first closed position. Moreover, as the pressure continues to increase, it continues to push the diaphragm


64


into the cavity


56


until the common upper contact


66


engages the outer lower contacts


60


,


62


such that the multiple contact fluid pressure switch


50


is in the second closed position.




Referring now to

FIGS. 9-12

, a second alternative multiple contact fluid pressure switch is shown and generally designated


100


.

FIGS. 9-12

show that the multiple contact fluid pressure switch


100


includes a preferably glass, flat, rectilinear plate


102


having a peripheral rib


104


extending from the upper surface of the plate


102


around the outer periphery of the upper surface to establish a cavity


106


above the plate


102


within the confines of the peripheral rib


104


. In a preferred embodiment, the cavity


106


is airtight.




As shown in

FIGS. 9-12

, a preferably gold central lower contact


108


is affixed to the upper surface of the plate


102


within the cavity


106


and extends from within the cavity


106


through the peripheral rib


104


. Also, a preferably gold outer lower contact


110


is affixed to the upper surface of the plate


102


within cavity


106


such that it surrounds the central lower contact


108


. As shown, the outer lower contact


108


also extends from within the cavity


106


through the peripheral rib


104


.





FIGS. 9-11

show that a diaphragm


112


is disposed on top of the peripheral rib


104


so that it completely encloses the cavity


106


. Preferably, the cavity


106


is airtight. As shown, a preferably gold, flexible common upper contact


114


is attached to the interior surface of the diaphragm


112


directly above the central lower contact


108


and the outer lower contact


110


. As described below, the common upper contact


114


can engage the central lower contact


108


and the outer lower contact


110


.




It is to be understood that as the external pressure increases, the multiple contact fluid pressure switch


100


moves between an open position shown in

FIG. 9

, a first closed position shown in

FIG. 10

, and a second closed position shown in FIG.


11


. Specifically, as the pressure overcomes the stiffness of the diaphragm, the diaphragm


112


is partially pushed into the cavity


106


until the common upper contact


114


engages the central lower contact


108


such that the multiple contact fluid pressure switch


100


is in the first closed position. Moreover, as the pressure continues to increase, it continues to push the diaphragm


112


into the cavity


106


until the common upper contact


114


engages the outer lower contact


110


such that the multiple contact fluid pressure switch


100


is in the second closed position.




With the configuration of structure described above, it is to be appreciated that the multiple contact fluid pressure switch


10


,


50


,


100


provides a pressure activated switch having multiple contacts. Moreover, the configuration of the multiple contact fluid pressure switch


10


,


50


,


100


minimizes the amount of current required to operate circuitry connected thereto. Also, providing a multiple contact multiple contact fluid pressure switch


10


,


50


,


100


for use in systems that do not require the full range measurement capabilities of piezo-resistive pressure sensors allows the use of all digital electronics which reduce production costs.




While the particular MULTIPLE CONTACT FLUID PRESSURE SWITCH as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it is to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. section


112


, sixth paragraph, unless the element is expressly recited using the phrase “means for.”



Claims
  • 1. A multiple contact fluid pressure switch, comprising:a plate; a rib extending from the plate to establish a cavity on the plate; two lower contacts in the cavity; a diaphragm enclosing the cavity; and an upper contact disposed on the diaphragm, the multiple contact fluid pressure switch being movable between an open position wherein the upper contact does not engage the lower contacts, a first closed position wherein the upper contact engages only one lower contact, and a second closed position wherein the upper contact engages both lower contacts.
  • 2. The multiple contact fluid pressure switch of claim 1, wherein the diaphragm is disposed on the rib.
  • 3. The multiple contact fluid pressure switch of claim 2, further comprising:a central rib extending from the plate, the central rib dividing the cavity into a first cavity and a second cavity; a first lower contact being disposed within the first cavity; and a second lower contact being disposed within the second cavity.
  • 4. The multiple contact fluid pressure switch of claim 3, wherein the diaphragm is a first diaphragm that encloses the first cavity and the second cavity and the switch further comprises:a second diaphragm affixed to the first diaphragm, the second diaphragm spanning the area above the second cavity.
  • 5. The multiple contact fluid pressure switch of claim 4, further comprising:a first upper contact affixed to the first diaphragm above the first lower contact; and a second upper contact affixed to the first diaphragm above the second lower contact.
  • 6. The multiple contact fluid pressure switch of claim 5, wherein the switch is movable between an open position wherein the upper contacts do not engage the lower contacts, a first closed position wherein the first upper contact engages the first lower contact, and a second closed position wherein the first upper contact continues to engage the first lower contact and wherein the second upper contact engages the second lower contact.
  • 7. The multiple contact fluid pressure switch of claim 2, wherein the lower contacts comprise:a central lower contact; and a first outer lower contact spaced from the central lower contact.
  • 8. The multiple contact fluid pressure switch of claim 7, wherein the upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the first outer lower contact.
  • 9. The multiple contact fluid pressure switch of claim 8, further comprising:a second outer lower contact placed below the common upper contact.
  • 10. The multiple contact fluid pressure switch of claim 9, wherein the switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least one of the outer lower contacts.
  • 11. The multiple contact fluid pressure switch of claim 1, wherein the lower contacts comprise:a central lower contact; and an outer lower contact spaced from the central lower contact and surrounding the central lower contact.
  • 12. The multiple contact fluid pressure switch of claim 11, wherein the upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the outer lower contact.
  • 13. The multiple contact fluid pressure switch of claim 12, wherein the switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least a portion of the outer lower contact.
  • 14. A fluid pressure switch, comprising:a cavity; two lower contacts disposed within the cavity; a diaphragm enclosing the cavity; and an upper contact disposed on the diaphragm above the lower contacts, the fluid pressure switch being movable between an open position wherein the upper contact does not engage the lower contacts, a first closed position wherein the upper contact engages one lower contact, and a second closed position wherein the upper contact engages both lower contacts.
  • 15. The fluid pressure switch of claim 14, comprising:a first cavity and a second cavity; a first lower contact being disposed within the first cavity; and a second lower contact being disposed within the second cavity.
  • 16. The fluid pressure switch of claim 15, wherein the diaphragm is a first diaphragm that encloses the first cavity and the second cavity and the switch further comprises:a second diaphragm affixed to the first diaphragm, the second diaphragm spanning the area above the second cavity.
  • 17. The fluid pressure switch of claim 16, further comprising:a first upper contact affixed to the first diaphragm above the first lower contact; and a second upper contact affixed to the first diaphragm above the second lower contact.
  • 18. The fluid pressure switch of claim 17, wherein the switch is movable between an open position wherein the upper contacts do not engage the lower contacts, a first closed position wherein the first upper contact engages the first lower contact, and a second closed position wherein the first upper contact continues to engage the first lower contact and wherein the second upper contact engages the second lower contact.
  • 19. The fluid pressure switch of claim 13, wherein the lower contacts comprise:a central lower contact; and a first outer lower contact spaced from the central lower contact.
  • 20. The fluid pressure switch of claim 19, wherein the upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the first outer lower contact.
  • 21. The fluid pressure switch of claim 20, further comprising:a second outer lower contact placed below the common upper contact.
  • 22. The fluid pressure switch of claim 21, wherein the switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least one of the outer lower contacts.
  • 23. The fluid pressure switch of claim 14, wherein at least one of the lower contacts comprise:a central lower contact; and an outer lower contact spaced from the central lower contact and surrounding the central lower contact.
  • 24. The fluid pressure switch of claim 23, wherein the upper contact is a common upper contact that is affixed to the diaphragm above the central lower contact and the outer lower contact.
  • 25. The fluid pressure switch of claim 24, wherein the switch is movable between an open position wherein the common upper contact does not engage the lower contacts, a first closed position wherein the common upper contact engages the central lower contact, and a second closed position wherein the common upper contact continues to engage the central lower contact and wherein the common upper contact engages at least a portion of the outer lower contact.
US Referenced Citations (7)
Number Name Date Kind
3584168 Halpert et al. Jun 1971 A
3585328 Fiore et al. Jun 1971 A
4767943 Adler et al. Aug 1988 A
4771143 Hoffmann Sep 1988 A
5177579 Jerman Jan 1993 A
5802911 Cahill et al. Sep 1998 A
6194678 Yoshikawa et al. Feb 2001 B1
Foreign Referenced Citations (2)
Number Date Country
402024929 Jan 1990 JP
402223119 Sep 1990 JP