Low tire pressure warning system
First Claim
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1. A pneumatic tire low pressure warning system comprising:
- a wheel;
a pneumatic tire carried by the wheel, the tire being normally inflated to a specified pressure;
a low pressure air switch, the low pressure air switch including a housing secured to the wheel and having a cavity therein exposed to the internal pneumatic tire pressure temperature, a normally closed valve unit carried on the housing and having an inlet side exposed to the internal tire pressure and having an outlet side, a bellows within the cavity, means coupling the bellows and the normally closed valve unit, the normally closed valve unit being opened when the bellows is extended, and a manually actuated equalizer valve extending through the wheel and being operable to selectively provide pneumatic communication between the bellows interior and the pneumatic tire interior and seal the bellows interior from the pneumatic tire interior, the equalizer valve being operated to provide pneumatic communication between the interior of the tire and the bellows when the tire is at the specified pressure and thereafter closed so as to establish a temperature variable reference pressure within the bellows, the bellows being extended when the air pressure in the pneumatic tire decreases to a certain level below the reference pressure within the bellows to open the normally closed valve unit;
an actuator carried by the wheel external of the pneumatic tire;
means pneumatically coupling the outlet side of the normally closed valve unit to the actuator, the actuator being operated by tire air supplied thereto when the normally closed valve unit is opened by the bellows; and
means for sensing the operation of the actuator and providing a warning, whereby the warning represents the decrease in the pneumatic tire pressure below the manually set, temperature variable reference pressure in the bellows.
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Abstract
A vehicle pneumatic tire low pressure warning system including a low pressure air switch carried on the vehicle rotating wheel assembly which compares a reference pressure and the tire pressure and couples the tire air to an actuator on the rotating wheel assembly when the difference exceeds a specified amount. The tire air operates the actuator to position a magnet to actuate a reed switch sensor on a stationary member of the vehicle. A signal is provided in response to the reed switch actuation to warn the vehicle operator of the low tire pressure.
18 Citations
4 Claims
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1. A pneumatic tire low pressure warning system comprising:
- a wheel;
a pneumatic tire carried by the wheel, the tire being normally inflated to a specified pressure;
a low pressure air switch, the low pressure air switch including a housing secured to the wheel and having a cavity therein exposed to the internal pneumatic tire pressure temperature, a normally closed valve unit carried on the housing and having an inlet side exposed to the internal tire pressure and having an outlet side, a bellows within the cavity, means coupling the bellows and the normally closed valve unit, the normally closed valve unit being opened when the bellows is extended, and a manually actuated equalizer valve extending through the wheel and being operable to selectively provide pneumatic communication between the bellows interior and the pneumatic tire interior and seal the bellows interior from the pneumatic tire interior, the equalizer valve being operated to provide pneumatic communication between the interior of the tire and the bellows when the tire is at the specified pressure and thereafter closed so as to establish a temperature variable reference pressure within the bellows, the bellows being extended when the air pressure in the pneumatic tire decreases to a certain level below the reference pressure within the bellows to open the normally closed valve unit;
an actuator carried by the wheel external of the pneumatic tire;
means pneumatically coupling the outlet side of the normally closed valve unit to the actuator, the actuator being operated by tire air supplied thereto when the normally closed valve unit is opened by the bellows; and
means for sensing the operation of the actuator and providing a warning, whereby the warning represents the decrease in the pneumatic tire pressure below the manually set, temperature variable reference pressure in the bellows.
- a wheel;
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2. A low pressure warning system for a vehicle having a wheel mounted pneumatic tire normally inflated to a specified pressure, said system comprising:
- an actuator carried on the wheel external to the tire, the actuator including a base member of magnetic material, a magnet having first and second magnetic pole faces, the first pole face being normally positioned adjacent the base member to form a magnetic latching force therebetween, a first magnetic flux carrying member secured to and approximately covering the second magnetic pole face, a second magnetic flux carrying member secured to the base member and in close proximity to the first magnetic flux carrying member when the first pole face is in its normal position, the first and second flux carrying members and the base member cooperating to form a closed magnetic flux path between the first and second pole faces when the first pole face is in its normal position, a pressure responsive member including a sealed chamber and a moveable element having one side exposed to the pressure within the sealed chamber, and means coupling the moveable element and the magnet;
a low pressure air switch carried by the wheel and responsive to internal tire pressure;
an air hose coupling the air switch to the sealed chamber, the air switch coupling tire air to the sealed chamber when the tire air pressure decreases to a certain pressure less than the specified pressure, the moveable element being moved by tire air pressure coupled thereto against the magnetic latching force between the magnet and the base member to move the magnet from its normal position to an extended position to generate an external magnetic field; and
means carried on the vehicle and stationary relative thereto for sensing the external magnetic field and generating a signal representing the decreased tire pressure.
- an actuator carried on the wheel external to the tire, the actuator including a base member of magnetic material, a magnet having first and second magnetic pole faces, the first pole face being normally positioned adjacent the base member to form a magnetic latching force therebetween, a first magnetic flux carrying member secured to and approximately covering the second magnetic pole face, a second magnetic flux carrying member secured to the base member and in close proximity to the first magnetic flux carrying member when the first pole face is in its normal position, the first and second flux carrying members and the base member cooperating to form a closed magnetic flux path between the first and second pole faces when the first pole face is in its normal position, a pressure responsive member including a sealed chamber and a moveable element having one side exposed to the pressure within the sealed chamber, and means coupling the moveable element and the magnet;
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3. A low pressure warning system for a vehicle having a wheel mounted pneumatic tire normally inflated to a specified pressure, said system comprising:
- a low pressure air switch, the low pressure air switch including a housing secured to the wheel and having a cavity therein exposed to the internal pneumatic tire pressure and temperature, a normally closed valve unit carried on the housing and having an inlet side exposed to the internal tire pressure and having an outlet side, a bellows within the cavity, means coupling the bellows and the normally closed valve unit, the normally closed valve unit being opened when the bellows is extended, and a manually actuated equalizer valve extending through the wheel and being operable to selectively provide pneumatic communication between the bellows interior and the pneumatic tire interior and seal the bellows interior from the pneumatic tire interior, the equalizer valve being operated to provide pneumatic communication between the interior of the tire and the bellows when the tire is at the specified pressure and thereafter closed so as to establish a temperature variable reference pressure within the bellows, the bellows being extended when the air pressure in the pneumatic tire decreases to a certain level below the reference pressure within the bellows to open the normally closed valve unit;
an actuator carried on the wheel external to the tire, the actuator including a base member of magnetic material having an open ended chamber formed on the end thereof, a magnet having first and second magnetic pole faces, the first pole face being normally positioned adjacent the bottom of the chamber to form a magnetic latching force therebetween, the magnet approximately extending the length of the chamber, spring means for biasing the magnet into the chamber, a first magnetic flux carrying member secured to and approximately covering the second magnetic pole face, a second magnetic flux carrying member secured to the walls of the chamber adjacent the first magnetic flux carrying member when the first pole face is in its normal position to complete a magnetic short circuit flux path between the first and second pole faces, a pressure responsive member including a sealed chamber and a moveable element having one side exposed to the pressure within the sealed chamber, and means coupling the moveable element and the magnet;
means for pneumatically coupling the outlet side of the normally closed valve unit to the sealed chamber, the normally closed valve unit being opened by the bellows to couple tire air pressure to the sealed chamber when the tire air pressure decreases to a determined pressure less than the specified pressure, the moveable element being moved by tire air pressure coupled thereto against the magnetic latching force between the magnet and the base member and the bias of the spring means to move the magnet from its normal position to an extended position to generate an external magnetic field;
a reed switch carried on the vehicle adjacent the path traced by the magnet in its extended position, the reed switch being closed by the external magnetic field;
latching means responsive to the closure of the reed switch for generating a continuous signal; and
indicating means responsive to the signal for providing a warning of the low tire pressure.
- a low pressure air switch, the low pressure air switch including a housing secured to the wheel and having a cavity therein exposed to the internal pneumatic tire pressure and temperature, a normally closed valve unit carried on the housing and having an inlet side exposed to the internal tire pressure and having an outlet side, a bellows within the cavity, means coupling the bellows and the normally closed valve unit, the normally closed valve unit being opened when the bellows is extended, and a manually actuated equalizer valve extending through the wheel and being operable to selectively provide pneumatic communication between the bellows interior and the pneumatic tire interior and seal the bellows interior from the pneumatic tire interior, the equalizer valve being operated to provide pneumatic communication between the interior of the tire and the bellows when the tire is at the specified pressure and thereafter closed so as to establish a temperature variable reference pressure within the bellows, the bellows being extended when the air pressure in the pneumatic tire decreases to a certain level below the reference pressure within the bellows to open the normally closed valve unit;
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4. A low pressure warning system for a vehicle having a wheel mounted pneumatic tire normally inflated to a specified pressure, said system comprising:
- an actuator carried on the wheel external to the tire, the actuator including a magnet means having first and second magnetic pole faces and being moveable between a normal and an extended position, a hollow base member of magnetic material receiving the magnet means for forming a closed magnetic flux path between the first and second pole faces when the magnet means is in its normal position, one of the pole faces being adjacent the base member to form a magnetic latching force therebetween when the magnet means is in its normal position, a pressure responsive member including a chamber and a moveable element having one side exposed to the pressure within the chamber, and means coupling the moveable element and the magnet;
a low pressure air switch carried by the wheel and responsive to internal tire pressure;
an air hose coupling the air switch to the chamber, the air switch coupling tire air to the chamber when the tire air pressure decreases to a certain pressure less than the specified pressure, the moveable element being moved by tire air pressure coupled thereto against the magnetic latching force between the magnet and the base member to move the magnet from its normal position to an extended position to generate an external magnetic field; and
means carried on the vehicle and stationary relative thereto for sensing the external magnetic field and generating a signal representing the decreased tire pressure.
- an actuator carried on the wheel external to the tire, the actuator including a magnet means having first and second magnetic pole faces and being moveable between a normal and an extended position, a hollow base member of magnetic material receiving the magnet means for forming a closed magnetic flux path between the first and second pole faces when the magnet means is in its normal position, one of the pole faces being adjacent the base member to form a magnetic latching force therebetween when the magnet means is in its normal position, a pressure responsive member including a chamber and a moveable element having one side exposed to the pressure within the chamber, and means coupling the moveable element and the magnet;
Specification
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Current AssigneeGeneral Motors Corporation (Motors Liquidation Co. GUC Trust)
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Original AssigneeGeneral Motors Corporation (Motors Liquidation Co. GUC Trust)
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InventorsStewart, John A., Haven, Harold A.
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Primary Examiner(s)Waring, Alvin H.
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Application NumberUS05/601,319Time in Patent Office536 DaysField of Search340/58, 200/61.22, 200/61.25, 200/82 R, 200/83 L, 335/205US Class Current340/445CPC Class CodesB60C 23/007 having multiple wheels arra...B60C 23/0425 Means comprising permanent ...
