Cylinder and piston for compressor or vacuum pump

In an oiless compressor or vacuum pump having a housing which defines a compression chamber and a cylindrical guideway co-axial with the compression chamber, and having a piston which is reciprocable in said housing, said piston having a head which is received in said compression chamber to compress a gas therein when said piston is reciprocated and a cylindrical base received in said guideway to guide said head as said piston is reciprocated, the improvement wherein:

• said compression chamber is defined by a cylinder sleeve in which said head of said piston reciprocates, said cylinder sleeve having a bottom end which extends axially into said guideway;
• and
• said base of said piston has a top surface facing said cylinder sleeve, said top surface defining an axially facing cavity radially inward of a top end of said base of said piston, said sleeve extending into said cavity when said piston is at a top dead center position;
• wherein a skirt is provided on said base adjacent to said top end of said base, said skirt sliding against said guideway;
• wherein said top-end skirt is secured in an axial position on said base which overlaps said piston head axially and said axially facing cavity is at an axial position which is radially between said top-end skirt and said piston head;
• and
• a second skirt is provided on said base adjacent to a bottom-end thereof and spaced apart from said top-end skirt, said skirt sliding against said guideway.

In an oiless compressor or vacuum pump having a housing which defines a compression chamber and a cylindrical guideway co-axial with the compression chamber, and having a piston which is reciprocable in said housing, said piston having a head which is received in said compression chamber to compress a gas therein when said piston is reciprocated and a cylindrical base received in said guideway to guide said head as said piston is reciprocated, the improvement wherein:

• said compression chamber is defined by a cylinder sleeve in which said head of said piston reciprocates, said cylinder sleeve having a bottom end which extends axially into said guideway;
• said base of said piston has a top surface facing said cylinder sleeve, said top surface defining an axially facing cavity radially inward of a top end of said base of said piston, said sleeve extending into said cavity when said piston is at a top dead center position;
• and
• said head is of a diameter which is slightly smaller than said cylinder sleeve so as to be slidably received in said cylinder sleeve and said diameter extends into said cavity.