GA01300_0902 - 04/2006 - © by Leybold Vacuum
8
Description
The oil pump is fitted in the front end plate on the coupling side of the pump
module. The oil suction line is placed low, resulting in a large usable oil
reservoir.
The oil is separated from the gas in the TRIVAC BCS in two steps as descri-
bed above. First, small droplets are coalesced into large drops in the inter-
nal demister (2/11) fitted above the exhaust valve (2/10). Then, the large
drops fall into the oil reservoir as the exhaust gas is diverted by the inner
walls of the oil case. Thus a low loss of oil is obtained. This and the large
usable oil reservoir ensure long intervals between oil changes even at high
intake pressures.
The vacuum is maintained by the TRIVAC BCS through an integrated
hydropneumatic anti-suckback valve (2/3) which is controlled via the oil
pressure.
During operation of the TRIVAC BCS the control piston (4/3) remains sea-
led against a spring (4/2) by the oil pressure. The valve disc (4/6) of the anti-
suckback valve is held at the lower position by its own weight (valve open).
When the pump stops (because it has been switched off or because of a
failure), the oil pressure drops and the spring (4/2) presses the control
piston (4/3) up. Thus a connection is provided between the oil case or the
oil reservoir (4/1) and the piston (4/4) of the anti-suckback valve.
Due to the pressure difference between the oil case and the intake port the
oil presses the piston (4/4) up and the valve plate (4/6) against the valve
seat (4/5). The quantity of oil in the oil reservoir (4/1) prevents the entry of
air into the intake port (2/1) at the beginning of this process.
Fig. 2 Sectional drawing of the TRIVAC BCS
Key to Fig. 2
1 Intake port
2 Dirt trap
3 Anti-suckback valve
4 Intake channel
5 Vanes
6 Pump chamber
7 Rotor
8 Cover plate, connection for inert gas ballast
9 Exhaust channel
10 Exhaust valve
11 Internal demister
12 Spring buckles
13 Cover plate, connection for oil filter
Separation of oil and gas
Anti-suckback valve
