Pneumatic device for controlling the filling of a container

Claim 1

In a pneumatic device for controlling the filling of containers, said device comprising at least one filling head including a liquid supply tube for introducing liquid into a container and a level detecting probe through which a flow of air is simultaneously introduced into said container, said probe having an opening positioned near a predetermined level to which a container in filling position relative to said head is to be filled, said liquid supply tube being provided with a liquid control valve controlling the flow of liquid therethrough, and control means connected between said liquid control valve and said level detecting probe, the improvement according to which said control means comprises: a detector valve responsive to the presence of a container in said filling position and a first gas control valve connected to supply gas to said detector valve, a pneumatic distributor having a control member therein which controls the flow of gas through said distributor, the output of said distributor being connected to actuate said liquid control valve and the output of said first gas valve being connected to said distributor at one side of said control member, the pressure supplied to said distributor from said first gas valve being insufficient to operate said control member to open said liquid control valve when said detector valve is open, but sufficient to do so when said detector valve is closed, a pneumatic pressure regulator having a main inlet, a main outlet and a control inlet the application of pressure to which increases the flow between said main inlet and main outlet, and said main inlet connected to the output of said pneumatic distributor and its main outlet connected to the other side of said control member, a flow-limiting device connected between the output of said pneumatic distributor and the control inlet of said pneumatic pressure regulator, a second gas control valve having a first input connected to said flow-limiting device and a second input connected to a source of compressed gas, the output of said second gas-control valve being connected to supply said level-detecting probe only with gas from said flow limiting device when said second gas valve is in a first position and only with gas from the second input of said second gas control valve when said second gas control valve is in a second position, whereby whenever flow from said second gas control valve input through said second gas valve is blocked by closure of the opening in said probe or by location of said second gas valve in its second position, the resulting pressure in the second input of said second gas control valve is applied to the control inlet of said pneumatic pressure regulator to increase the output pressure applied through said regulator to said other side of said control member, thereby reversing the position of said distributor to close said liquid supply valve.