Patent ID: 7976285

Claim:
A method of charging a compressed air storage tank for a vehicle so that a detected pressure in the storage tank increases from a first pressure to a second pressure, said method comprising: determining the first pressure according to a first detected vehicle engine load, wherein the first pressure is in a range from a minimum low-limit pressure to a maximum low-limit pressure, wherein determining the first pressure comprises: (a) determining if excess engine power is available from the first detected vehicle engine load; and (b) setting the first pressure, wherein setting the first pressure comprises: (i) setting the first pressure to the maximum low-limit pressure if excess engine power is available and the pressure detected in the storage tank is equal to the maximum low-limit pressure; (ii) setting the first pressure to a pressure at which excess engine power becomes available if the pressure detected in the storage tank is less than the maximum low-limit pressure and greater than the minimum low-limit pressure; and (iii) setting the first pressure to the minimum low-limit pressure if the detected pressure in the storage tank is equal to the minimum low-limit pressure; starting a charge cycle when the pressure detected in the storage tank is at least as low as the first pressure; charging the compressed air storage tank to increase the detected pressure from the maximum low-limit pressure to a minimum high-limit pressure; determining the second pressure according to a second detected vehicle engine load, wherein the second pressure is in a range from the minimum high-limit pressure to a maximum high-limit pressure; and stopping the charge cycle when the pressure detected in the storage tank is at least as high as the second pressure.