The Working Principle
Northey compressors and vacuum pumps are purely rotary machines, yet they possess the positive action of the piston type due to the unique principles of design and operation, and must not be confused with either reciprocating or other rotary machines.
Pistons, piston rings, connecting rods, sliding vanes, eccentric drums, valves and other often troublesome components producing friction, vibration, noise, inertia forces, and wear have been eliminated.
The diagrams clearly illustrate the cycle, and it should be noted that during the transition from position 4 to position 1, when the rotors "mesh", the ports are closed, and the whole of the working chamber is at uniform pressure.
There is therefore no need to maintain a "seal" between the rotors. Clearances are accordingly provided here, so that the rotors cannot touch and wear each other.
1. |
 |
2. |
 |
|
(a) |
Commencement of Cycle Inlet port about to open into induction space 1 |
(a) |
Induction well advanced in space 1 |
|
(b) |
Compression commencing into space C |
(b) |
Delivery commencing from space C |
3. |
 |
4. |
 |
|
(a) |
Induction complete. Inlet port shut off from space 1 |
(a) |
"Change over" position. Seal broken between rotors, freeing undelivered air into induced charge. |
|
(b) |
Delivery complete. Small portion of compressed charge trapped in space C. |
(b) |
Cycle recommences at (1), with induced charge now transferred to "compression side" of rotor tips. |
