Air Pump Cylinder

Abstract

An air pump cylinder has a housing, a cover and an O-ring. The housing includes a connecting tube. The connecting tube has a plurality of projections extending therefrom. The cover is hermetically engaged with the connecting tube of the housing and includes a cap. The cap has an annular sidewall and a plurality of grooves. The grooves are formed in the annular sidewall and each groove has an axial portion and a locking portion. The projections of the connecting tube of the housing are disposed into the axial portions of the grooves and the cover is then rotated to make the projections engage the locking portions of grooves and to make the O-ring tightly clamped between the connecting tube of the housing and the cap of the cover. Therefore, the air pump cylinder can be easily assembled and manufactured without the use of bolts.

What is claimed is: 
     
         1 . An air pump cylinder comprising:
 a housing including:
 a base tube having:
 a front end, and 
 a piston chamber defined in the base tube; and 
 
 a connecting tube integrally formed on the front end of the base tube and having:
 an outer surface; 
 a valve chamber defined in the connecting tube and communicating with the piston chamber of the base tube; and 
 a plurality of projections extending from the outer surface of the connecting tube; 
 
   an O-ring made of a resilient material and mounted around the connecting tube of the housing; and   a cover hermetically engaged with the connecting tube of the housing and including:
 a cap having:
 a closed front; 
 an annular sidewall having an inner surface; 
 a receiving chamber defined between the closed front and the annular sidewall of the cap for receiving the connecting tube of the housing and the O-ring; and 
 a plurality of grooves formed in the inner surface of the annular sidewall, corresponding to the projections of the connecting tube of the housing and each groove having:
 an axial portion; and 
 a locking portion extending from and communicating with a front end of the axial portion; and 
 
 
 a joint integrally formed on the closed front of the cap and having a passage defined therein and communicating with the receiving chamber of the cap; and 
   wherein the projections of the connecting tube of the housing are disposed into the axial portions of the grooves and the cover is then rotated to make the projections engage the locking portions of grooves and to make the O-ring tightly clamped between the connecting tube of the housing and the cap of the cover.   
     
     
         2 . The air pump cylinder as claimed in  claim 1 , wherein
 the connecting tube of the housing has
 a cylindrical rear portion extending from the front end of the base tube and having:
 a front surface; 
 an outer surface from which the projections extend; and 
 an outer diameter; and 
 
 a cylindrical front portion having:
 a cylindrical first step extending from the front surface of the rear portion and having:
 a front surface; and 
 an outer diameter being smaller than the outer diameter of the rear portion; 
 
 a cylindrical second step extending from the front surface of the first step and having an outer diameter being smaller than the outer diameter of the first step; and 
 an annular step surface formed between the first step and the second step; and 
 
   the receiving chamber of the cap of the cover has
 a first tank extending through the cap from an open rear thereof and having an inner diameter corresponding to the outer diameter of the first step of the front portion; 
 a second tank extending through the cap, communicating with the first tank and having an inner diameter corresponding to the outer diameter of the second step of the front portion; and 
 an annular step surface formed between the first tank and the second tank and corresponding to the step surface of the front portion; and 
   wherein the O-ring is mounted around the second step of the front portion, is disposed in the first tank of the receiving chamber and is tightly clamped between the step surface of the front portion and the step surface of the receiving chamber.   
     
     
         3 . The air pump cylinder as claimed in  claim 1 , wherein the housing includes an interface wall formed between the base tube and the connecting tube and having:
 a center;   a hole formed through the center of the interface wall and communicating with the piston chamber of the base tube and the valve chamber of the connecting tube; and   an abutting surface formed around the hole.   
     
     
         4 . The air pump cylinder as claimed in  claim 2 , wherein the housing includes an interface wall formed between the base tube and the connecting tube and having:
 a center;   a hole formed through the center of the interface wall and communicating with the piston chamber of the base tube and the valve chamber of the connecting tube; and   an abutting surface formed around the hole.   
     
     
         5 . The air pump cylinder as claimed in  claim 4  further having a pressure gauge connector mounted on the annular sidewall of the cap of the cover and having an interior communicating with the receiving chamber of the cap. 
     
     
         6 . The air pump cylinder as claimed in  claim 1 , wherein the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess. 
     
     
         7 . The air pump cylinder as claimed in  claim 2 , wherein the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess. 
     
     
         8 . The air pump cylinder as claimed in  claim 3 , wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess. 
     
     
         9 . The air pump cylinder as claimed in  claim 4 , wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess. 
     
     
         10 . The air pump cylinder as claimed in  claim 5 , wherein the interface wall of the housing has a recess and the annular sidewall of the cap of the cover has a boss engaging the recess. 
     
     
         11 . The air pump cylinder as claimed in  claim 6 , wherein
 the recess is formed in a periphery of a front surface of an interface wall of the housing; and   the boss extends from a rear surface of the annular sidewall of the cap of the cover.   
     
     
         12 . The air pump cylinder as claimed in  claim 7 , wherein
 the recess is formed in a periphery of a front surface of an interface wall of the housing; and   the boss extends from a rear surface of the annular sidewall of the cap of the cover.   
     
     
         13 . The air pump cylinder as claimed in  claim 8 , wherein
 the recess is formed in a periphery of a front surface of the interface wall of the housing; and   the boss extends from a rear surface of the annular sidewall of the cap of the cover.   
     
     
         14 . The air pump cylinder as claimed in  claim 9 , wherein
 the recess is formed in a periphery of a front surface of the interface wall of the housing; and   the boss extends from a rear surface of the annular sidewall of the cap of the cover.   
     
     
         15 . The air pump cylinder as claimed in  claim 10 , wherein
 the recess is formed in a periphery of a front surface of the interface wall of the housing; and   the boss extends from a rear surface of the annular sidewall of the cap of the cover.