A vane motor consists of housing with an eccentric bore, in which runs a rotor with vanes in it that slide in and out. The force differential created by the unbalanced force of the pressurized fluid on the vanes causes the rotor to spin in one direction. This particular motor provides rotation in only one direction. The rotating element is a slotted rotor which is mounted on a drive shaft. Each slot of the rotor is fitted with a freely sliding rectangular vane. The rotor and vanes are enclosed in the housing, the inner surface of which is offset from the drive shaft axis.When the rotor is in motion, the vanes tend to slide outward due to centrifugal force. The distance the vanes slide is limited by the shape of the rotor housing. This motor operates on the principle of differential areas. When compressed air is directed into the inlet port, its pressure is exerted equally in all directions. Since area a is greater than area b, the rotor will turn counterclockwise. Each vane, in turn, assumes the positions and the rotor turn continuously. The potential energy of the compressed air is thus converted into kinetic energy in the form of rotary motion and force. The air at reduced pressure is exhausted to the atmosphere. The shaft of the motor is connected to the unit to be actuated. Many vane-type motors are capable of providing rotation in either direction. This motor operates on the same principle as the vane motor. The two ports may be alternately used as inlet and outlet, thus providing rotation in either direction. Their purpose is to hold the vanes against the housing during the initial starting of the motor, since centrifugal force does not exist until the rotor begins to rotate.
Special application- a rotary vane motor uses a gear train arrangement for controlling the position of the vanes as well as the compression ratio of the motor. The motor includes a first pair of vanes namely a leading and trailing vane defining a working chamber therebetween and an opposed second pair of vanes namely a leading and trailing vane defining therebetween a second working chamber. Preferably the motor uses a pair of second order elliptical gears for controlling movement of the vanes to define an intake stage, a compression stage, an expansion stage, and an exhaust stage. In a preferred structure of the motor both the intake port and the exhaust port are movable to change or alter the intake stage and the exhaust stage respectively.
