Pressure alarm system for motor vehicle tires

• US 4,890,090 A
• Filed: 06/06/1988
• Issued: 12/26/1989
• 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:
  US07/202,262
• Time in Patent Office: 568 Days
• Field of Search: 340/58, 340/442, 73/146.2, 73/146.3, 73/146.8, 73/146.5, 200/61.25, 200/83 N, 200/61.22, 116/34 R, 116/34 A, 116/34 B
• 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: H01H 35/346 in which the movable contact is formed or directly supported by the diaphragm

Abstract

A pressure sensitive electrical switch consists of a housing in which two pressure chambers are formed. The pressure chambers are separated by a flexible diaphragm. The flexible diaphragm is made from electrical conductive material. Conductors extend into the housing to provide terminals which are spaced from the diaphragm when the pressure in the two chambers is substantially equal. When a pressure differential is established between the two chambers, the diaphragm may be deflected into contact with one or other of the terminals of the conductors. In use, the diaphgram is connected in an electrical circuit and each of the conductors is connected in an electrical circuit such that when contact is made between the diaphragm and one of the conductors, the electrical circuit will be complete. Because the diaphragm is at least partially permeable, this switch is intended to be used to monitor changes in pressure which occur between the two chambers over a relatively short period of time. This switch is used to advantage in a tire pressure warning system in which it serves to activate a transmitter which will transmit a signal indicating that the pressure in the tire has changed at an undesirable rate. In this system a receiver is provided for receiving the signal which is emitted by the transmitter and an alarm is provided which is activated by the receiver to generate an alarm signal.

Claims

1. A pneumatically operated pressure sensitive electrical switch for detecting a hazardous rate of change of pressure in a pressure sensitive pneumatic system comprising;

(a) a housing having a pressure chamber formed therein,

(b) a flexible diaphragm mounted in said housing, said diaphragm forming a wall of said pressure chamber which serves to separate the pressure chamber from aid pneumatic pressure system in use, said diaphragm being free to move independently to and fro between a first position and a second position in response to said hazardous rate of change in the pressure in the pressure system, said diaphragm being sufficiently permeable to permit air to pass therethrough at a rate which will serve to permit equalization of the pressure on opposite sides of the diaphragm at a rate that would prevent the detection of a change in the pressure in said pressure sensitive system which occurs at a rate that is less than said hazardous rate, said diaphragm being sufficiently impermeable to prevent the passage of air therethrough at a rate which will serve to prevent equalization of the pressure on opposite sides of the diaphragm at a rate which would prevent the movement of the diaphragm from said first position to said second position when said hazardous rate of change occurs in the pressure in said pressure sensitive system,

(c) switch means carried by said housing and communicating with said diaphragm to open and close in response to movement of said diaphragm to and from between said first and second positions.

3. A switch as claimed in claim 1 wherein a pressure sensing chamber is formed in said housing, said pressure sensing chamber being separated from said pressure chamber by said diaphragm.

2. A switch as claimed in claim 11 wherein said flexible diaphragm is an electrically conductive diaphragm and said switch means comprises;

(a) first conductor means having a first contact disposed opposite said flexible diaphragm so as to be out of contact with said diaphragm when it is in said first position and to make contact with said diaphragm when it is in said second position, said first conductor means being accessible for connection to an electrical circuit,

(b) means for connecting said diaphragm to said electrical circuit such that said switch is open when said diaphragm is in its first position and closed when said diaphragm is in its second position.

4. A switch as claimed in claim 2, wherein said means for connecting said diaphragm to an electrical circuit comprises a second conductor means mounted in said housing and having a second contact located in a side-by-side spaced relationship with respect to said first contact so as to be out of contact with said diaphragm when it is in its first position and to make contact with said diaphragm when it is in said second position such that the first and second conductors are electrically connected to one another through said diaphragm when said diaphragm is in its second position.

5. In an inflation chamber of a tire which is inflated to a predetermined inflation pressure the improvement of an alarm system for generating an alarm signal when air leaks from the inflation chamber at a rate which could be hazardous comprising:

(a) a housing mounted in said inflation chamber, said housing having a pressure chamber formed therein,

(b) a flexible diaphragm mounted in said housing, said diaphragm forming a wall of said pressure chamber which serves to separate the pressure chamber from said inflation chamber such that said diaphragm is free to move independently to and fro between a first position and a second position in response to said hazardous rate of change in the pressure in the inflation chamber, said diaphragm being sufficiently permeable to permit air to pass therethrough at a rate which will serve to permit equalization of the pressure in the pressure chamber and the inflation chamber on opposite sides of the diaphragm at a rate that will prevent the detection of a change in the pressure in said inflation chamber which occurs at a rate that is less than said hazardous rate, said diaphragm being sufficiently impermeable to prevent the passage of air therethrough at a rate which will serve to prevent equalization of the pressure in the pressure chamber and the inflation chamber on opposite sides of the diaphragm at a rate which would prevent the movement of the diaphragm from said first position to said second position when said hazardous rate of change occurs in the pressure in said pressure sensitive system,

(c) alarm means communicating with said diaphragm and operable to generate an alarm signal in response to movement of said diaphragm from said first position to said second position.

6. An alarm system as claimed in claim 5 wherein said alarm means comprises;

(a) transmitter means located within said inflation chamber and electrically connected to a power source through said pressure sensitive switch so as to be activated when said switch is closed to transmit a warning signal,

(b) alarm generating means remote from said tire for generating an alarm signal,

(d) receiver means remote from said tire for receiving the warning signal which is emitted by the transmitter, said receiver means communicating with said alarm generating means to activate said alarm generating means to cause it to generate said alarm signal when the warning signal is received.