Pressure sensor system

• US 5,119,066 A
• Filed: 09/04/1990
• Issued: 06/02/1992
• Est. Priority Date: 06/06/1988
• Status: Expired due to Fees

• Current Assignee: Jan Ballyns
• Original Assignee: Jan Ballyns
• Inventors: Ballyns, Jan
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/577,297
• Time in Patent Office: 637 Days
• Field of Search: 340/442, 340/447, 340/590-593, 340/626, 340/665, 200/61.22, 200/61.25, 200/83 R, 200/83 N, 200/83 A, 200/81 R, 116/34 R, 116/34 A, 116/34 B, 73/146.3, 73/146.2, 73/146.5, 73/146.8
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver
• CPC Class Codes: B60C 23/0494 Valve stem attachments positioned inside the tyre chamber
• CPC Class Codes: H01H 35/346 in which the movable contact is formed or directly supported by the diaphragm

Abstract

A pressure sensor that responds to a predetermined rate of change of pressure in the fluid medium comprises a housing that encloses a pressure chamber which has a divider wall that consists of a printed circuit board and a flexible diaphragm which is permeable. The divider wall serves to separate the pressure chamber from the pressure sensitive system in which the sensor is used. The sensor may be used in a pneumatic tire and in such use the flexible diaphragm will be deflected to activate a transmitter when the pressure in the tire changes at a hazardous rate. The sensor will not activate the transmitter when the rate of change of pressure is less than a hazardous rate of change.

Claims

1. A pressure sensor switch that is responsive to a predetermined rate of change of pressure in a fluid medium of a pressure sensitive system comprising;

(a) a housing having an enclosure formed therein,

(b) a divider wall assembly comprising;

a printed circuit board and a flexible diaphram arranged in a face-to-face relationship and clamped together within said housing and dividing said enclosure into an input chamber and a pressure chamber, the printed circuit board having a normally open alarm signal generating circuit thereon, circuit closing means carried by the flexible diaphram for movement, in response to a predetermined pressure differential between the pressure in the input chamber and the pressure in the pressure chamber, from a first position in which the circuit closing means it is out of contact with said circuit to a second position in which it serves to complete the circuit to generate an alarm signal,

(c) said divider wall assembly being permeable to said fluid medium and having a sufficient permeability to permit the fluid medium to pass therethrough at a rate that will serve to permit equalization of the pressure in the pressure chamber and the pressure sensitive system to prevent displacement of the diaphragm to the second position when the rate of change of pressure in the pressure system is less than that which is indicative of a predetermined rate of change, the permeable divider wall assembly being sufficiently impermeable to prevent the passage of fluid medium therethrough at a rate that will serve to prevent equalization of the pressure in the pressure chamber and the pressure sensitive system at a rate that would prevent movement of the diaphragm from said first position to said second position when the predetermined rate of change occurs in the pressure sensitive system, and

(d) input passage means opening into said input chamber.

2. A pressure sensor as claimed in claim 1 wherein said diaphram is shaped to provide a cup-shaped portion that cooperates with the circuit board to form a collapsible chamber therebetween which communicates with the input chamber through first vent passage that opens through the board.

3. A pressure sensor as claimed in claim 2 wherein said circuit has spaced terminals located proximate said first vent passage and wherein said circuit closing means comprises conductor means which are disposed opposite said terminal means so as to be movable into and out of contact therewith in response to movement of the cup-shaped portion to complete and interupt said alarm circuit.

4. A pressure sensor as claimed in claim 1 wherein said printed circuit board has first and second and valve stem passages opening therethrough and first and second valve members having a stem extending freely through said first and second valve passages respectively and a shoulder portion which is too large to enter said first or second valve stem passages, each valve member having a valve passage that extends inwardly from a first end of the valve member through the shoulder portion into the stem portion, said valve passage having an orifice that opens laterally through a side wall of the stem portion.

5. A pressure sensor as claimed in claim 4 wherein said flexible diaphragm has a main body portion and first and second sleeve portions integrally formed therewith that project from opposite sides of the main body through the first and second stem passages of said board and surround the first and second stems respectively to normally close the orifice that opens through the side wall of the stem portion that is located therein, said first and second sleeves being flexible such that when the pressure in the input chamber exceeds the pressure in the pressure chamber by a predetermined amount the first sleeve will be deflected away from the first stem to permit the fluid medium to pass from the input chamber into the pressure chamber and when the pressure in the pressure chamber exceeds the pressure in the input chamber by a predetermined amount the second sleeve will be deflected away from the second stem to permit the fluid medium to pass from the pressure chamber into the input chamber.

6. A pressure sensor as claimed in claim 5 wherein housing has oppositely disposed first and second walls and said flexible diaphram is located opposite said second wall and wherein interior wall means extends from the second wall toward the circuit board and serves to clamp the flexible diaphram against the circuit board.

7. A pressure sensor switch that is responsive to a predetermined rate of change of pressure in a fluid medium of a pressure sensitive system comprising;

(a) a housing having an enclosure formed therein and oppositely disposed first and second walls,

(b) a printed circuit board having a vent passage and first and second stem passages opening therethrough, an alarm circuit on said board having open terminals on a first side of said board proximate said vent passage,

(c) first and second valve members each having a stem that is proportioned to pass freely through said first and second stem passages and a shoulder portion which is too large to enter said first or second stem passages, each valve member having a valve passage that extends inwardly from a first end of the valve member through the shoulder portion into the stem portion, said valve passage having an orifice that opens laterally through a side wall of the stem portion,

(d) a flexible diaphragm having first and second sleeve portions integrally formed therewith that project from opposite sides thereof, each sleeve portion having a passage opening therethrough that is proportioned to accommodate the stem portion of one of the valve members in a close fitting relationship to close the orifice that opens through the side wall of the stem portion, a portion of said diaphragm being cup-shaped and having an inner face,

(e) conductor means mounted on said inner face of said cup-shaped portion of said diaphram,

(f) said board and diaphram being arranged in a face-to-face relationship and mounted within said housing in a position in which they divide said enclosure into an input chamber and a pressure chamber, said cup-shaped portion cooperating with the circuit board to form a collapsible chamber therebetween which communicates with the input chamber through said vent passage, said conductor means being disposed opposite said terminal means so as to be movable into and out of contact therewith in response to movement of the cup-shaped portion to activate and deactivate said alarm circuit,

(g) input passage means opening into said input chamber for admitting the fluid medium to said input chamber,

(h) said first valve member being located in said enclosure with the shoulder portion thereof clamped between said first wall and the circuit board with the stem thereof extending through said first stem passage into said first sleeve such that the orifice of the first stem is normally closed by the first sleeve, said first sleeve being flexible such that when the pressure in the input chamber exceeds the pressure in the pressure chamber by a predetermined amount the first sleeve will be deflected away from the first stem to permit the fluid medium to pass from the input chamber into the pressure chamber,

(i) said second valve member being located in said enclosure with the shoulder portion thereof clamped between said second wall and the circuit board with the stem thereof extending through said second vent passage into said second sleeve such that the orifice of the second stem is normally closed by the second sleeve, said second sleeve being flexible such that when the pressure in the pressure chamber exceeds the pressure in the input chamber by a predetermined amount the second sleeve will be deflected away from the second stem to permit the fluid medium to pass from the pressure chamber into the input chamber,

(j) interior wall means extending from the second wall toward the circuit board and clamping the flexible diaphram against the circuit board,

(k) said diaphragm being permeable to said fluid medium and having a sufficient permeability to permit the fluid medium to pass therethrough at a rate that will serve to permit equalization of the pressure in the pressure chamber and the pressure sensitive system to prevent displacement of the diaphragm to the second position when the rate of change of pressure in the pressure system is less than that which is indicative of a predetermined rate of change, the permeable wall being sufficiently impermeable to prevent the passage of fluid medium therethrough at a rate that will serve to prevent equalization of the pressure in the pressure chamber and the pressure sensitive system at a rate that would prevent movement of the diaphragm from said first position to said second position when the predetermined rate of change occurs in the pressure sensitive system.