Central tire inflation system

• US 5,313,995 A
• Filed: 01/24/1990
• Issued: 05/24/1994
• Est. Priority Date: 06/29/1987
• Status: Expired due to Term

• Current Assignee: Dana Heavy Vehicle Systems Group LLC (Dana, Inc.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Schultz, Gary R.
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Lorin, Francis J.
• Application Number:
  US07/469,719
• Time in Patent Office: 1,581 Days
• Field of Search: 152/415, 152/416, 152/417, 137/224, 137/226, 137/102, 137/625.2, 141/38, 141/83, 141/95
• US Class Current: 152/416
• CPC Class Codes: B60C 23/00318 on the wheels or the hubs
• CPC Class Codes: B60C 23/00354 Details of valves
• CPC Class Codes: B60C 23/00363 Details of sealings
• CPC Class Codes: B60C 23/00372 characterised by fluid diagrams
• CPC Class Codes: Y10T 137/36 With pressure-responsive pressure-control means

Abstract

A central tire inflation system for a vehicle is disclosed 10 including a controller 222 for preselecting one of several desired air pressures for the tires 12 by actuating one of the push buttons 226, 228 or 230. The system 10 will adjust the tire pressure to the preselected pressure. Should the operator sense enemy fire or believes combat is eminent, the "run flat" button 234 is actuated which causes the electronic timer of the control unit 237 to cause the automatic measurement of tire pressure every few seconds instead of several times an hour. Should one of the tires 12 be damaged while the button 234 is actuated, the damaged tire will be immediately identified and the system 10 will assume the inflate mode and supply air to the damaged tire so long as the leakage rate does not exceed the capacity of the source 138 of pressurized air.

Claims

1. A central tire inflation system for sensing and maintaining selected air pressures in tire chambers of tire assemblies mounted for rotation at opposite ends of at least one axle assembly supporting a chassis of a vehicle controlled by an operator;

the system comprising;

an air source for providing pressurized air at pressure at least equal to normally maximum tire chamber air pressure;

selector means including means selectively activatable by the operator for preselecting one of several desired tire chamber air pressures;

a control circuit including means automatically operative several times per hour to activate a pressure check mode to compare tire pressure signals from a sensing means with a preselected tire pressure, and automatically operative to activate inflation and steady-state modes respectively in response to the sensed tire pressure being less than or within predetermined limits of the preselected tire pressure;

an air circuit for connecting the air source to each tire chamber, the air circuit including rotary seal means connecting non-rotatably mounted parts of the air circuit with rotatably mounted parts of the air circuit for communicating are therebetween;

a control valve secured to each tire assembly, each control valve having a first port connected to one of the rotatably mounted parts of the air circuit, a second port connected to the tire chamber of the associated tire assembly, and valving means movable to a position blocking air communication between the ports in response to the air circuit being vented to atmosphere and movable to a position unblocking the air communication between the ports in response to pressurization of the air circuit;

valve means operative in response to the automatic activation of the steady-state mode by the control circuit means to vent the air circuit to atmosphere for moving the valving means of the control valves to the blocking positions, the valving means operative in response to activation of the check mode to momentarily connect the air source to the air circuit to pressurize the air circuit and move the valving means of the control valves to the unblocking positions for establishing air pressure in the air circuit at the sensing means representive of tire pressure, and the valve means operative in response to automatic activation of the inflation mode by the control circuit means to again connect the air source to the air circuit for increasing the tire pressure;

characterized by;

switch means manually activated by an operator during vehicle operation in hazard zones for automatically increasing the frequency of activating the check modes by the control circuit means, for automatically more quickly detecting low tire pressure conditions, and for automatically more quickly activating the inflation modes to prevent flat tire conditions within the air capacity of the air supply.

2. The central tire inflation system of claim 1, wherein said control circuit means automatically increases the frequency of activating the check modes to several times per minute in response to the manual activation of the switch means.

3. A central tire inflation system for sensing and maintaining selected pressures in tire chambers of tire assemblies mounted for rotation at opposite ends of at least one axle assembly supporting a chassis of a vehicle controlled by an operator;

the system comprising;

an air source for providing pressurized air at pressure at least equal to normally maximum tire chamber air pressure;

selector means including means selectively activated by the operator for preselecting one of several desired tire chamber air pressures;

a control circuit including means automatically operative several times per hour to activate a pressure check mode to compare tire pressure signals form a sensing means with a preselected tire pressure, and automatically operative to activate inflation, deflation and steady-state modes respectively in response to the sensed tire pressure being less than or greater than or within limits of the preselected tire pressure;

an air circuit for connecting the air source to each tire chamber, the air circuit including rotary seal means connecting non-rotatably mounted parts of the air circuit with rotatably mounted parts of the air circuit for communicating air therebetween;

a control valve secured to each tire assembly, each control valve having a first port connected to one of the rotatably mounted parts of the air circuit, a second port connected to the tire chamber of the associated tire assembly, and valving means movable to a position blocking the second ports in response to air pressure at the first port being substantially atmospheric pressure and movable to a position unblocking the second ports in response to a non-atmospheric pressure at the first port;

valve means operative in response to the automatic activation of the steady-state mode by the control circuit means to vent the air circuit to atmosphere for moving the valving means of the control valves to the blocking positions and for unpressurized operation of the rotary seal means;

the valving means operative in response to the automatic activation of the check, inflate and deflate modes to apply the non-atmospheric pressure to the first ports for moving the valving means to the unblocking positions; and

the valve means operative in response to;

activation of the check mode to momentarily apply the non-atmospheric pressure for establishing an air pressure in the air circuit at the sensing means representive of tire pressure, activation of the inflate mode to connect the air source to the first ports for increasing the tire pressure, and activation of the deflate mode to connect the second ports to vent means for decreasing the tire pressure;

characterized by;

switch means manually activated by an operator during vehicle operation in hazard zones for automatically increasing the frequency of activating the check modes by the control conduit means from several times per hour to several times per minute for automatically more quickly detecting low tire pressure conditions, and for automatically more quickly activating the inflation modes to prevent flat tire conditions within the air capacity of the air supply.