Patent ID: 8517137

Claim:
A method for operating a hybrid internal combustion engine and air motor system comprising at least one chamber having a drivable member and at least one intake valve and at least one exhaust valve, and a reservoir connected to the chamber through the exhaust valve, comprising: in an air motor mode of operation, calculating air motor efficiency according to the following equation: η ⁢ ⁢ AM = efficiency ⁢ ⁢ of ⁢ ⁢ air ⁢ ⁢ motor = - ⅆ W ⅆ A and wherein A = ⁢ thermodynamic ⁢ ⁢ availability ⁢ ⁢ in ⁢ ⁢ reservoir = ⁢ ( E - E o ) + P o * ( V - V o ) - T o * ( S - S o ) dA=rate of change of A E=Internal energy of air in reservoir=f(m, T t ) m=mass of air in reservoir=P t *V/(R*T t ) T t =Temperature of air in reservoir P t =Pressure of air in reservoir V=Volume of reservoir at P t and T t R=gas constant E o =Internal energy of air in reservoir at ambient pressure and temperature P o =Ambient pressure V=Volume of air in reservoir at ambient pressure and temperature T o =Temperature of ambient air S=Entropy of air in reservoir=f(P t , T t ) S o =Entropy of air in reservoir at ambient pressure and temperature POW=Engine brake power=N*T b N=Engine speed (rev/time) T b =Engine brake torque W=Engine brake work=POW dt dW=rate of change of W and selecting an intake and exhaust valve opening and closing timing sequence for maximizing air motor efficiency so that ⅆ ( η ⁢ ⁢ AM ) ⅆ ( Valve ⁢ ⁢ Timing ) = 0 and ⅆ 2 ⁢ ( η ⁢ ⁢ AM ) ⅆ 2 ⁢ ( Valve ⁢ ⁢ Timing ) < 0.