Pressure sensor system

• US 5,055,826 A
• Filed: 04/16/1990
• Issued: 10/08/1991
• 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:
  US07/509,631
• Time in Patent Office: 540 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, 73/146.5, 73/146.8, 73/146.2
• 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 35/28 Compensation for variation of ambient pressure or temperature
• 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 permeable wall and flexible diaphragm that separates 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 comprising:

(a) a stem having a side wall surrounding a vent chamber that opens into one end of the stem, a vent passage opening from the vent chamber through the side wall of the stem,

(b) a tubular sleeve mounted on said stem and overlying said vent passage, said tubular sleeve being flexible so as to be movable to and fro between a first position in which it extends in close proximity to said vent passage and a second position which is spaced outwardly from the first position with respect to the step in response to a variation in pressure in the vent chamber, said sleeve being electrically conductive and forming a first terminal of said switch,

(c) a second terminal of said switch bieng located opposite said tubular sleeve so as to be spaced therefrom when the sleeve is in the said first position and to contact the sleeve when the sleeve is in said second position to open and close said switch in response to movement of said sleeve.

2. A pressure sensitive switch as claimed in claim 1 wherein the stem has an outer face in which an annular recess is formed between first and second ananular shoulders, said vent passage opening from said vent chamber into said annular recess, said tubular sleeve bridging and closing the annular recess and having opposite ends thereof mounted on said annular shoulders.

3. A pressure sensitive switch as claimed in claim 2 wherein said second terminal has a contact surface surrounding said sleeve.

4. A pressure sensitive switch as claimed in claim 3 wherein a portion of the second contact surface of the second terminal is located opposite said vent passage.

5. A pressure sensitive switch as claimed in claim 2 wherein at least one of said opposite ends of said sleeve is resiliently deformable to separate from the shoulder on which it is mounted to permit the fluid medium to discharge from the annular recess when the pressure in the pressure chamber exceeds a predetermined valve.

6. A pressure sensitive switch as claimed in claim 1 further comprising a housing having a divider wall therein that separates a pressure chamber from an input chamber, said stem being mounted on said divider wall such that said vent chamber communicates with said pressure chamber and said tubular sleeve is located in said input chamber and separates the vent passage from the input chamber.

7. A pressure sensitive switch as claimed in claim 6 wherein said divider wall is a printed circuit board which has a circuit printed thereon which is electrically connected to the first and second terminals.

8. A pressure sensitve switch as claimed in claim 7 wherein the stem is an electrical conductor that communicates between the circuit of the printed circuit board and the tubular sleeve.

9. A pressure sensitive switch as claimed in claim 1 wherein said tubular sleeve is fluid permeable member which is sufficiently permeable 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 in the input chamber to prevent displacement of the tubular member from the first position to the second positon when the rate of change in the pressure and the input chamber is less than that which is indicative of a predetermined hazardous rate of change, the permeable member being sufficient 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 input chamber at a rate that would prevent movement of the sleeve from said first position to said second position when the predetermined rate of change occurs in the chamber.

10. A pressure sensitve switch as claimed in claim 6 wherein a pressure balancing passage is formed in the divider wall that communicates between the pressure chamber and the input chamber, and a fluid permeable member is mounted in said pressure balancing passage, said fluid permeable member being sufficiently permeable 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 in the input chamber to prevent displacement of the tubular member from the first position to the second position when the rate of change in the pressure and the input chamnber is less than that which is indicative of a predetermined hazardous rate of change, the permeable member being sufficient 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 input chamber at a rate that would prevent movement of the sleeve from said first position to said second position when the predetermined rate of change occurs in the chamber.

11. A pressure sensitive switch as claimed in claim 10 wherein the fluid permeable member is in the form of a plug which is seated in said pressure balancing passage.

12. A pressure sensitive switch as claimed in claim 6 wherein the said housing comprises first and second segments which cooperate with one another to secure the divider wall therebetween.

13. A pressure sensitive switch as claimed in claim 6 wherein a second stem is mounted on said divider wall, said second stem having a side wall in which an input passage is formed which has a first portion of its length that opens inwardly from the input chamber and the second portion of its length which opens through the side wall into the pressure chamber and a second tubular sleeve mounted on said second stem and overlying and normally closing said second portion, said second tubular sleeve being flexible so as to be movable with respect to the second stem to permit the fluid medium to pass therethrough when the pressure in the input chamber is substantially greater than a predetermined operating pressure.