The CPSRE has a ratchet like rotor with smooth edges, which is placed inside a circular casing. Spring loaded vanes are placed in radial direction along the casing as shown in figure. The rotor vanes and casing has an oil seal between them, which forms a chamber between each vane, rotor teeth and casing. CPSRE consists of two rotors on either side of the casing and is locked to the same shaft. The two rotors are locked to the output shaft at a given angular offset between their teeth. The primary rotor is for induction and compression of air and the secondary rotor for combustion and exhaustion.