Pneumatic motor

Abstract

A pneumatic motor includes a cylinder and a rotor disposed in the cylinder. The rotor includes an axle, and main and secondary blades are slidably received in a plurality of main and secondary sliding slots formed on the axle. The secondary blades touch an inner wall of the cylinder to promote torque output when located at angles equal to or smaller than a specific angle from an inlet of the cylinder. On the contrary, the secondary blades are away from the inner wall of the cylinder to reduce friction between the rotor and the cylinder when located at angles larger than the specific angle from the inlet. Thus, revolution speed of the rotor is retained in a tolerant range, and torque output is promoted significantly.

What is claimed is: 
     
         1 . A pneumatic motor, comprising:
 a cylinder, enclosing a receiving room, an inlet, and a outlet, the inlet and the outlet communicating with the receiving room respectively, the cylinder having an inner wall defined on a circumference of the receiving room; and a rotor, including an axle, a plurality of main blades, and a plurality of secondary blades which are shorter than the main blades, the axle defining an axial direction and a radial direction, the axle being rotatably disposed in the receiving room deviating from a center of the receiving room, the axle has an outer surface, the axle forming a plurality of main sliding slots and secondary sliding slots which are recessed radially, the main and the secondary sliding slots being annularly arranged around the outer surface, each main blade being disposed in one of the main sliding slot and being able to slide radially therein, each secondary blade being disposed in one of the secondary sliding slot and being able to slide radially therein, each main blade being able to rotate and to abut against the inner wall when the axle rotates, secondary blades which are located at angles equal to or smaller than a specific angle from the inlet being able to touch the inner wall when the axle rotate;   wherein the specific angle is equal to or smaller than 160 degrees.   
     
     
         2 . The pneumatic motor of  claim 1 , further including a limitation mechanism, the limitation mechanism enabling each secondary blade to slide radially to protrude outside of the outer surface of the axle but not to leave the secondary sliding slot when the axle rotates. 
     
     
         3 . The pneumatic motor of  claim 1 , wherein the axle and the main blades partition the receiving room into a plurality of air chamber, each secondary sliding slot has a smaller depth than a depth of each main sliding slot, a number of the secondary sliding slots is equal to a number of the main sliding slots, the main and the secondary sliding slots are arranged alternately. 
     
     
         4 . The pneumatic motor of  claim 2 , wherein the limitation mechanism includes a plurality of ribs and limitation slots, the ribs protrude from two opposite sides of each secondary blade, the limitation slots are formed at two opposite sides of each secondary sliding slot, the ribs are slidably disposed in the limitation slots respectively to prevent the ribs and the secondary blades from leaving the limitation slots and the secondary sliding slots. 
     
     
         5 . The pneumatic motor of  claim 4 , wherein the ribs, the secondary blades, the limitation slots, and the secondary sliding slots has a same axial length. 
     
     
         6 . The pneumatic motor of  claim 2 , wherein the limitation mechanism includes a plurality of abutting slots, a plurality of tenons, and a plurality of positioning slots, the abutting slots are formed on two opposite sides of each secondary sliding slots respectively, each tenon is disposed in one of the abutting slot and are fixed in one of the secondary sliding slot, the positioning slots are formed on the secondary blades, each tenon is slidably received in one of the positioning slot to abut against the secondary blades. 
     
     
         7 . The pneumatic motor of  claim 6 , wherein a number of the tenons is twice than a number of the secondary blades, each of the two opposite sides of each secondary blade disposes a tenon.