Improved zero pressure accumulating conveyor control

Claim 2

(2) An accumulating conveyor having a plurality of load carrying rollers defining a conveying run, a drive belt extending in the direction of said run beneath said rollers and belt supporting tension roller means disposed beneath said belt for supporting and urging said belt into driving engagement with selected ones of said load carrying rollers for conveying loads along said conveyor and for dropping said belt from said selected ones of said load carrying rollers to disengage driving forces therefrom, said belt supporting rollers being divided into independent groups defining accumulating zones in said load carrying rollers, each group having pneumatic actuator means for engaging and disengaging said belt from portions of said load carrying rollers, a downstream discharge zone at a discharge end of said conveyor, and pneumatic control means for controlling said actuator means, said pneumatic control means comprising, a source of pressurized fluid, respective control valves in each zone connected between said source and said respective actuator means in each zone, a load sensor in each zone operably connected to the respective control valve for said zone, a shuttle valve in each upstream zone from said discharge zone and having an output connected to an actuator means in the respective zone, a first input connected to the control valve in said respective zone, and a second input, said second input of said shuttle valves, including that shuttle valve in an upstream zone immediately adjacent the discharge zone, connected at least indirectly to the control valve of the preceding zone, said control valves in upstream zones passing fluid from said source to the respective shuttle valves and actuator means in their respective zones and to the shuttle valve and actuator means in a next upstream zone when said sensors are not activated, and venting said shuttle valves when said sensors are activated, characterised by: a selectively actuable, two position, master control valve means connected between the control valve of said discharge zone and the actuator means for said discharge zone, said master control valve means also connected to a source of pressurized fluid, said control valve in said discharge zone passing fluid to and through said master control valve means, in one position of said master control valve, to actuator means in said discharge zone when load sensor in said discharge zone is not activated, and venting said actuator means in said discharge zone through said master control valve when said load sensor therein is activated, said master control valve means in a second position connecting said source of pressurized fluid directly to the actuator means in said discharge zone, and disconnecting the control valve therefrom, regardless of the condition of the control valve in the discharge zone, and the control valve in said discharge zone connected to an input of the shuttle valve in the next upstream zone, whereby, when said master control valve is in said second position, said discharge zone is continuously operated and the adjacent upstream zone is operated in response to the condition of the control valve in the discharge zone and the control valve in its own zone.

Claim 3

(3) A pneumatic control for accumulating conveyors of the type having a downstream discharge zone and a plurality of upstream accumulating zones for accumulating loads, and having pneumatically operated means for selectively driving each zone in response to pneumatic control inputs, each zone including a control valve, each upstream zone including a shuttle valve, the control valve of each upstream zone passing pressurized air to the shuttle valve in the respective zone and to the shuttle valve in the next upstream zone when the respective zone is free of a load, the shuttle valve of each upstream zone passing pressurized air to the pneumatically operated means when said shuttle valve receives pressurized air from a control valve, characterised by: a master control valve in the discharge zone connected between the control valve in such zone and the pneumatically operated means thereof, said master control valve being connected to a source of pressurized air and in one position passing pressurized air directly from said source to said pneumatically operated means in said discharge zone, and in a second position operatively connecting said pneumatically operated means in said discharge zone to the control valve in said discharge zone, and said control valve in said discharge zone having an output connected directly to an input of a shuttle valve in the zone next upstream from the discharge zone.

Claim 4

(4) A pneumatic control means for a discharge zone of an accumulating conveyor having upstream accumulating zones wherein said conveyor includes respective pneumatically operated means for selectively driving each of said zones, characterised by the pneumatic control means comprising: a master control valve having a first input connected to a source of pressurized air, a single output connected to the pneumatically operated means of said discharge zone, and a second input, a control valve connected to said source of pressurized air and having an output connected to said second input of said master control valve, a shuttle valve means in an upstream zone adjacent said discharge zone for selectively passing pressurized fluid to the pneumatically operated means of said upstream zone, said shuttle valve means having at least one input, and said control valve output also connected directly to said input of said shuttle valve means.