THE HISTORY OF RECIPROCATING COMPRESSORS
What is a Reciprocating compressor and how does it work?
A reciprocating compressor is a positive displacement machine that uses a piston contained within a cylinder to produce compression. The piston is traditionally round, only because it is easier to manufacture round things than square things. The piston traverses the cylinder, sucking in atmospheric air at one end of its stroke, then compressing the air when it reaches the other end of its stroke. Reciprocating compressors may have more than one stage of compression (single stage), in which case they are called two stage, three stage or the like.
Where did the reciprocating compressor come from?
The principle of reciprocating mechanisms is hundreds of years old and the modern reciprocating compressor was undoubtedly driven from the research and development of the reciprocating steam engine.
Piston rings were originally designed for steam engines, not internal combustion engines as many people thought. Water pumps and pump primers probably were amongst the earliest machines to use piston rings. These were made from hemp rope and flax. In 1667, the famous Robert Boyle produced a pump using leather piston rings, using the water to keep the leather pliable.
The first practical steam driven reciprocating pump was built in 1698 by Thomas Savery. This machine didn't have a piston as such, but used a volume of water trapped inside a receiver to act as a piston, using steam to force the water out. The return stroke was affected by pouring cold water over the steam filled receiver, creating a partial vacuum which then sucked the water back in again.
In 1712, Thomas Newcomen designed a reciprocating steam engine that used a true piston and piston rod assembly.
Piston rings remained much of a muchness until James Watt built a piston using brass rings in the late 1700's. In 1769 Watt patented his single acting steam engine and in 1782 he patented his double acting steam engine.
In 1860, G.M. Miller designed a piston that had back vented piston rings. This allowed the use of a single piston ring, using the compression pressure to hold the ring against the cylinder wall. The principle is still in use, although the need to drill holes in the piston has long since past, the piston ring itself provides the energy to keep the ring tight against the cylinder wall. Modern reciprocating compressors use piston rings that adapt to the profile of the cylinder, using special designs to not only hug the barrel, but to allow sufficient lubrication to prevent seizure.
The invention of the reciprocating compressor is vague, many countries had been using steam engines and the technology produced reciprocating compressors.
However, the modern history of compressor bearing development is easier to establish.
Quite obviously the bearing life of a compressor is very important. Ball bearings were developed from roller bearings, which in turn can be traced back to pre-history when logs were used as rollers.
By the end of the 1890's balls could be manufactured to a tolerance of +/- 0.0005 inch. Although the mechanics for manufacturing fairly accurate ball bearings had been established, these had relied for some considerable time upon 'splash lubrication' to prevent seizure.
The principle of forced lubrication was invented during the late 1800's by Beauchamp Tower, an Englishman born in 1845. This allowed pressurised oil to be pumped into bearings thereby causing 'forced lubrication'.
The idea was taken one step further in 1890 by a draughtsman working for a UK steam engine manufacturer called Belliss & Morcom (now a compressor manufacturer). Albert Charles Pain drilled holes down the centre of crankshafts and conn-rods, allowing pressurised oil to be forced through these holes straight into the centre of the bearings. These holes were called oilways and the principle was later described in a paper to the Institution of Mechanical Engineers by Alfred Morcom in 1897.