Two-cylinder pump

Details Two-cylinder pump Two-cylinder pump

2001-03-21

2001-12-18

Freay, Charles G. (Department: 3746)

Pumps

Motor driven

Electric or magnetic motor

C417S415000, C417S521000, C417S423120

Reexamination Certificate

active

06331101

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to pumps, and particularly to an improved two-cylinder oilless air compressor.
A common form of air compressor employs a wobble piston driven by an electric motor. Examples are found in U.S. Pat. No. 3,961,868 issued Jun. 8, 1976, for “Air Compressor”, 3,961,869 issued Jun. 8, 1976, for “Air Compressor”, and 5,006,047 issued Apr. 9, 1991, for “Compressor With a Segmented Piston Rod Assembly”, all of which are owned by the assignee of this invention.
The wobble pistons of such air compressors have a peripherally extending seal which mates with the bore of the cylinder. No lubricant is required between the piston head and the cylinder bore. However, the movement of the piston seal in the cylinder bore generates considerable heat which must be dissipated.
Two-cylinder, in-line oilless piston compressors are also known. In one form, the two cylinders are arranged at opposite ends of a motor having a through drive shaft that mounts a wobble piston on each end. Each cylinder has a valve plate with flapper intake and exhaust valves mounted opposite the piston head. A cylinder head with intake and exhaust chambers is mounted on each cylinder and provides inlet and outlet chambers to the cylinders. The inlet and exhaust chambers of the cylinder heads are typically connected by separate tubes. Examples of the two-cylinder, in-line compressors are the 2600 series of compressors of Thomas Industries, Inc., the assignee of this invention.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved two-cylinder pump in which the cylinders are formed in identical housings attached without bolts at either end to the motor.
It is yet another object of this invention to provide such an air compressor having a one-piece cylinder head member which includes the cylinder heads for both cylinders and the integral tube connector between the chambers of the heads, the integral connectors being capable of acting as a handle or hook for the air compressor.
It is a further object of the invention to provide a method of assembling a two-cylinder air compressor that eliminates the need for bolts or screws.
In accordance with the invention, an air compressor has a motor with a through drive shaft. A cylindrical spacer or sleeve encircles the motor and identical housings are mounted at each end of the motor sleeve. Each housing includes a central bearing retainer which mounts a bearing for a respective end of the shaft. Each housing also mounts a cylinder. A piston having a rod attached eccentrically to the shaft has a head operating in the cylinder.
Also in accordance with the invention, an air compressor includes a motor having a through drive shaft, housings mounted at each end of the motor and including a cylinder, a piston attached to each end of the shaft and operating in the respective cylinder, and a one-piece head member for both cylinders. The head member includes head at each end for mounting to the cylinders, and integral tubes connecting the heads and spanning the distance between the housings.
A method of assembling such aboltless air compressor of the invention involves press fitting a bearing in each housing, press fitting one housing with its bearing onto one end of the motor sleeve, press fitting one end of the motor shaft into the bearing in the housing attached to the motor sleeve, press fitting the other housing with its bearing onto the other end of the motor sleeve while press fitting the other end of the motor shaft into the bearing in the other housing, and joining the housings with a rigid cylinder head.
The foregoing and other objects and advantages of the invention will appear in the following detailed description. In the detailed description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention.


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Thomas Compressor Pump, Field Service Manual, 2619CGH147-932, Thomas Industries, Inc. 1996.
Joseph Shigley, “Mechanical Engineering Design,” 3rd Ed., McGraw-Hill, pp. 63-65, 1977.

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