Patent Publication Number: US-6213725-B1

Title: Compressor having an improved piston

Description:
The present invention is a continuation-in-part of U.S. patent application Ser. No. 09/049,904, filed on Mar. 30, 1998, allowed. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a compressor, and more particularly to a compressor having an improved piston. 
     2. Description of the Prior Art 
     Typical compressors comprise a piston slidably received in a piston housing and a sealing ring solidly engaged on the piston and engaged between the piston and the piston housing, such that the typical piston or the sealing ring may be easily damaged. In addition, a number of valve members are required for controlling the air into and out of the piston housing. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional compressors. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a compressor includes a piston having a sealing ring loosely engaged thereon for preventing the sealing ring from solidly engaging with the piston housing and for preventing the piston from being easily damaged. 
     In accordance with one aspect of the invention, there is provided a compressor comprising a housing including a tube extended upward therefrom, and including a passage communicating the housing with the tube, the housing including a chamber formed therein, the tube including a pipe extended outward therefrom, a pressure gage connected to the pipe, a check valve including a valve member and a spring received in the tube for controlling an air flow passage from the housing to the pipe, a piston slidably received in the chamber of the housing, the piston including an outer peripheral portion having an annular groove formed therein, and including an upper portion having at least one notch formed therein and communicating with the annular groove of the piston, the piston including a rod extended downward therefrom, the annular groove of the piston including an upper portion having a size greater than a lower portion of the annular groove of the piston, a sealing ring loosely received in the annular groove of the piston and movable between the upper portion and the lower portion of the annular groove of the piston, the notch of the piston being communicating with the annular groove of the piston and being communicating with the chamber of the housing when the sealing ring is engaged in the upper portion of the annular groove of the piston, a base secured to the housing, and means for forcing the piston to move along the chamber of the housing in a reciprocating action, the forcing means including a motor secured to the base and having a pinion provided thereon, a gear rotatably secured to the base at a pivot shaft and engaged with the pinion and driven by the motor via the pinion, the gear including a first half having a plurality of first teeth and including a second half having a plurality of second teeth, the first teeth including a size greater than that of the second teeth, the gear including a casing provided thereon, and a block received in the casing and secured to the pivot shaft and rotated in concert with the gear, the block including a pin eccentric relative to the pivot shaft and coupled to the rod for coupling the piston to the block and the gear. 
     Further objectives and advantages of the present invention will become apparent from a careful reading of a detailed description provided hereinbelow, with appropriate reference to accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 are partial exploded views of a compressor in accordance with the present invention; 
     FIG. 3 is a perspective view of the compressor; 
     FIG. 4 is a partial cross sectional view taken along lines  4 — 4  of FIG. 3; and 
     FIGS. 5,  6 ,  7 ,  8  are partial cross sectional views illustrating the operation of the compressor. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, and initially to FIGS. 1-4, a compressor in accordance with the present invention comprises a base  1  including an opening  1 F formed therein for receiving a pinion  16  of a motor  15 . The motor  15  includes two screw holes  151  formed therein and aligned with two hubs  11  of the base  1  for receiving fasteners  13  which may secured the motor  15  to the base  1 . The base  1  includes an aperture  10  formed therein for receiving a pivot shaft  21  which has one end secured to the base  1  by a clamping ring  26  and which has the other end  27  extended outward of the base  1 . A bushing  14  is engaged in the aperture  10  of the base  1  and is engaged between the pivot shaft  21  and the base  1  and includes one or more flat surfaces  141  engaged with the corresponding flat surfaces  101  of the base  10  for preventing the bushing  14  from rotating relative to the base  1 . A housing  17  is secured to the base  1  and includes a tube  18  extended upward therefrom, and a pipe  1 D extended from the tube  18  and coupled to a nozzle or a hose via a coupler  1 C for output the pressurized air generated by the compressor. An air gage or a pressure gage  1 E is coupled to the pipe  1 D for measuring the air pressure in the housing  17 . The tube  18  includes a valve member  19  and a spring  1 A received therein and retained in the tube  18  with a cap  1 B for forming a check valve and for allowing the pressurized air to flow from the housing  17  to the coupler  1 C only and for preventing the pressurized air to flow back into the housing  17 . 
     A gear  22  includes a hole  28  formed therein for receiving the pivot shaft  21  and for rotatably securing to the base  1  at the pivot shaft  21  and includes a casing  2 A provided therein for receiving and supporting a block  20 . The block  20  includes a non-circular hole  23  formed therein for receiving and engaging onto a non-circular end  27  of the pivot shaft  21  such that the block  20  rotates in concert with the pivot shaft  21 . The block  20  includes a pin  24  spaced from the pivot shaft  21  or eccentric relative to the pivot shaft  21 . The pin  24  may also be directly extended from the gear  22 , instead of from the block  20 . The casing  2 A includes one or more shoulders each having a stop  2 B extended therefrom for engaging with and for retaining the block  20  of different thicknesses in the casing  2 A. The gear  22  includes one half having a number of teeth  22 A of a greater thickness than the teeth  22 B of the other half of the gear  22 . The teeth  22 A,  22 B of the gear  22  are engaged with the pinion  16  of the motor  15 . The engaging area between the pinion  16  and the teeth  22 A is greater than that between the other teeth  22 B and the pinion  16  such that the motor  15  may drive the gear  22  with a less power when the pinion  16  is engaged with the teeth  22 B and such that the motor  15  may effectively drive and rotate the gear  22 . 
     The housing  17  includes a chamber  171  (FIGS. 5-8) formed therein for slidably receiving a piston  4  which includes an annular groove  42  formed in the outer peripheral portion for receiving a sealing ring  43 . The housing  17  includes a passage  172  formed therein for communicating the chamber  171  of the housing  17  with the tube  18 . The sealing ring  43  may make an air tight seal between the piston  4  and the housing  17 . The piston  4  includes a rod  44  extended downward therefrom and having a ring  45  rotatably secured to the pin  24  with a bearing or a bushing  3  and secured to the pin  24  by a clamping ring  234 , such that the piston  4  may be moved along the housing  17  in a reciprocating action by the motor  15  via the eccentric pin  24  of the gear  22 . The piston  4  includes an upper surface  41  and includes one or more notches  46  formed in the upper portion thereof and communicating the annular groove  42  of the piston  4  (FIGS. 2,  5 - 8 ) with the chamber ( 171 ) of the housing ( 17 ). The annular groove  42  of the piston  4  includes a upper portion having a size greater than the lower portion of the piston  4  for loosely receiving the sealing ring  43 . 
     In operation, as shown in FIGS. 5-8, the piston  4  may be moved up and down along the housing  17  in a reciprocating action by the motor  15  via the eccentric pin  24  of the block  20  and the gear  22 . When the piston  4  is moved from the position in FIG. 7 toward the tube  18  in the position as shown in FIG. 5 via the intermediate position as shown in FIG. 8, the sealing ring  43  is forced toward the lower portion of the piston  4  to engage with the piston  4  such that the air may be forced into the tube  18  through the passage  172  (FIG.  5 ). When the piston  4  moves downward from the top position as shown in FIG. 5 to the lower position as shown in FIG. 7 via an intermediate position as shown in FIG. 6, the air may flow into the chamber  171  of the housing  17  via the annular groove  42  of the piston  4  and the notches  46  of the piston  4 . The air may then be forced into the tube  18  again when the piston  4  is forced toward the tube  18  again. The air may thus be effectively forced through the tube  18  without the other valve members. 
     Accordingly, the compressor includes a piston having a loosely received sealing ring for preventing the piston from being easily damaged. 
     Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.