Tire inflation and deflation valve

• US 4,895,199 A
• Filed: 12/28/1987
• Issued: 01/23/1990
• Est. Priority Date: 07/31/1986
• Status: Expired due to Term

• Current Assignee: PACCAR Incorporated
• Original Assignee: PACCAR Incorporated
• Inventors: Magnuson, Roland A., Shires, Robert G.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Bokan, Thomas E.
• Application Number:
  US07/138,647
• Time in Patent Office: 757 Days
• Field of Search: 152/415, 152/417, 152/418, 152/429, 137/223, 137/224, 137/226, 137/102, 417/231, 417/233, 141/38, 141/46, 141/3, 141/4, 141/66, 141/94, 141/95, 141/98, 141/192, 141/196, 141/197, 141/198, 340/58, 307/9, 307/10 R
• US Class Current: 152/415
• CPC Class Codes: B60C 23/003 comprising rotational joints between vehicle-mounted pressure sources and the tyres
• CPC Class Codes: Y10T 137/2544 Supply and exhaust type
• CPC Class Codes: Y10T 137/36 With pressure-responsive pressure-control means
• CPC Class Codes: Y10T 137/3646 Co-axial inflation and relief valves

Abstract

A central tire inflation and deflation system which quickly inflates or deflates tires to any one of a plurality of pressures selected by the vehicle operator. Inflation pressure is greater than the pressure to which the tires are to be inflated. The system uses a tire valve which deflates the tires when a pressure less than the instantaneous tire pressure but greater than a minimum value is applied to the valve. Pressure on rotary seals which connect the tires to the system is relieved when the system is not operating.

Claims

1. A tire inflation and deflation valve for use on a vehicle having pressurized tires comprising:

a body defining a fluid chamber having a tire port, a supply port and an atmospheric exhaust port therebetween and two separate seal seats positioned in the chamber between the tire port and the exhaust port;

a three position seal support member movably positioned within the chamber between first, second and third positions, having first and second seals positioned thereon a distance apart greater than the separation distance between the seal seats for independent engagement with the seal seats so that the support member in the first and third positions prevents fluid communication between the tire port and the exhaust port and allows fluid communication therebetween to deflate the tire when the seal support is in the second intermediate position; and

a movable, pressure reaction member having first and second stages positioned in the fluid chamber between the exhaust and supply ports to control the position of the seal support member and responsive to pressure applied at the supply port, the first stage having a pressure reaction surface exposed to the supply port and means for transferring the motion thereof to the seal support member over a limited distance, the second stage having a pressure reaction surface and means for transferring motion thereof to the seal support member wherein the combined effective area of both reaction surfaces is substantially larger than the area sealable by the first seal and wherein the effective area of the second stage is larger than the area sealable by the second seal so that a supply pressure, less than the tire pressure and greater than a preselected fraction of the tire pressure causes both stages to traverse the limited distance and move the support member from the first sealing position to the second, intermediate exhaust position to deflate the tires and so that reduction of the tire pressure approximately to the supply pressure causes the second stage to move the support member from the second, intermediate exhaust position to the third, sealing position, preventing further deflation of the tires.

2. The valve of claim 1, including means for quickly moving the seal support member from the second, intermediate exhaust position to the third sealing position when the pressure at the tire port is approximately equal to the pressure at the supply port.

3. The valve of claim 2, wherein the means for quickly moving the seal support member comprises means for restricting exhaust airflow from the tire port to the exhaust port when the seal support member is in the second, intermediate position, and means for decreasing the air flow resistance of the restricting means upon incremental displacement of the seal support member from the second, intermediate exhaust position to the third sealing position.

4. The valve of claim 3, wherein the restricting means comprises a pressure reaction surface positioned on the seal support between the tire port and the first seal and a throat portion of the valve body fluid chamber having a variable separation distance from the restricting means pressure reaction surface so that the size of the orifice formed therebetween increases rapidly as the seal support member is moved from the second, intermediate exhaust position to the third sealing position.

5. The valve of claim 1, wherein the combined effective area of the first and second stage pressure reaction surfaces on the pressure reaction member is approximately four times the area sealable by the first seal, whereby the preselected fraction of tire pressure is one fourth which when applied to the supply port moves the seal support member from the first sealing position to the second intermediate exhaust position.

6. The valve of claim 1, including a fluid passage between the supply port and the tire port, and a check valve in the passage positioned to allow fluid communication between the tire and supply ports only when pressure at the supply port exceeds pressure at the tire port to allow inflation of the tire.

7. A tire inflation and deflation valve for use on a vehicle having pressurized tires comprising:

a valve body defining a fluid chamber having a tire port, a supply port and an atmospheric exhaust port;

valve means for allowing fluid communication between the tire and exhaust ports to deflate the tire, only when fluid pressure at the supply port is less than the tire port pressure and greater than a predetermined fraction of the tire port pressure wherein the valve means for allowing fluid communications between the tire and exhaust ports has restricting means for quickly preventing fluid flow therebetween when the tire port pressure is approximately equal to the supply port pressure and comprising means for decreasing the air flow-resistance of the restricting means while the valve means is closing, and

means for allowing fluid communication between the tire and supply ports to inflate the tire only when the supply port pressure exceeds the tire port pressure.

8. The valve of claim 7 wherein the means for allowing fluid communication between the tire and exhaust ports has means for maintaining a substantially constant resistance to exhaust air flow during deflation.