Conveyors: power-driven – Conveyor system for arranging or rearranging stream of items – By longitudinally respacing successive articles in stream
Reexamination Certificate
1999-04-22
2001-11-13
Valenza, Joseph E. (Department: 3651)
Conveyors: power-driven
Conveyor system for arranging or rearranging stream of items
By longitudinally respacing successive articles in stream
C198S781060
Reexamination Certificate
active
06315104
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an accumulation conveyor control system and, in particular, to a system that employs zone control modules that are linked together to control conveyor operation without the need for a PLC or mechanical triggered devices.
BACKGROUND ART
Traditional “zero pressure” pallet accumulation conveyors (PAC) have utilized mechanical sensors and actuators. In one mode, as a product moves into a zone of these conveyors, a mechanical sensor is triggered. The sensor is linked to a mechanical actuator. The actuator then reacts with a clutch mechanism of the zone to either enable or disable the zone's movement. Using this concept, conveyor motors typically run continuously and the conveyor is often noisy due to the mechanical actuation of the zone. Where mechanical setups have not been either feasible or desirable, electrical sensors and actuators have been used. These devices have typically been connected to an external programmable logic controller (PLC). Software is then implemented that allows the PLC to control the conveyor in a similar fashion. Using these concepts results in unusually long setup times for either adjustment and/or wiring.
One example of an accumulation conveyor is disclosed in U.S. Pat. No. 5,042,644 to Davis. This patent discloses a zero pressure accumulation conveyor using a trigger assembly for the accumulation control. The trigger assembly is positioned along the conveyor run and is coupled to cam follower arms and valve bodies. Depression of the trigger assembly depresses the valve body, allowing air to pass from an air supply to a brake assembly cylinder. The brake assembly cylinder then restrains a torque tube thus isolating the driving force imparted by the drive shaft to the conveyor rollers.
U.S. Pat. No. 5,060,785 to Garrity discloses a control arrangement for an accumulating conveyer having a plurality of zones, each zone including an electrically-powered sensor. A logic circuit is associated with each sensor, the logic circuit comprising a first input, a second input from the sensor of its zone, a first output which sends a signal to the activator for that zone and a second output to send a signal to the input for the next zone. A circuit for each electronic sensor communicates with the circuit before and after itself to control the system. In this system, electronic sensors are used to indicate the presence of an article in a given zone. When the electric sensor senses an article blocking the sensing path, the signal interacts with the logic circuit to control the operation of the accumulation conveyor.
Accumulation conveyors using mechanical sensors and actuators are not without their disadvantages. First, in any system, the actuator reacts with a clutch mechanism of the zone to either enable or disable the conveyor's movement in that zone. Using this system, the conveyor motors typically run continuously. Moreover, the conveyor is often noisy due to the mechanical actuation of the zone.
While these mechanical systems have been replaced with electrical systems such as that disclosed in the Garrity patent, these electrical systems are not without their disadvantages either. The electrical systems containing logic circuits take an unusually long time for setup due to adjustments and/or wiring.
In light of the disadvantages noted above, a need has developed to provide accumulation conveyor controls which overcome the prior art's disadvantages. In response to this need, the present invention provides an accumulation conveyor control which eliminates both mechanical control such as trigger mechanisms, pneumatic systems, and logic circuit control devices.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide an improved accumulation conveyor control system.
Another object of the present invention is a control module for each zone of an accumulation conveyor.
A still further object of the present invention is an accumulation conveyor system which eliminates the need for mechanical and programmable logic circuits.
One other object of the present invention is a method of accumulating articles on an accumulation conveyor without the need for controls that require mechanical assist and/or software implementation.
Other objects and advantages of the present invention will become apparent as a description thereof proceeds.
In satisfaction of the foregoing objects and advantages, the present invention provides an improvement in accumulation conveyor systems comprising a plurality of conveyor zones, the conveyor zones including an infeed conveyor zone, at least one intermediate conveyor zone, and an outfeed conveyor zone, each zone having at least one driving roller and a plurality of following rollers, the driving roller linked to a drive by a clutch mechanism. In one aspect of the invention, the improved system comprises a sensor for each zone, each sensor capable of detecting a presence or absence of an article in a respective zone, and a solenoid for each zone. Each solenoid is linked to each zone clutch mechanism. A relay for energizing or de-energizing the solenoid to electrically actuate or de-actuate the clutch mechanism of each zone is provided, relay operation based on a presence or an absence of an article in a space of each zone and a presence or absence of an article in a space of a downstream zone. Actuation of the clutch mechanism permits zone roller operation and deactuation of the clutch mechanism prevents zone roller operation.
A motor control center can be provided to link a single power source to a single motor, the motor control center including a transformer to step down the power source for powering each control module. The motor can be linked to each clutch mechanism by a drive member. In this way, one system having the motor, motor control center and various zones can be installed and connected to a single source of power.
The motor control center can include means for powering the motor only when the presence of an article is detected for the plurality of conveyor zones. The relays for each zone can be contained in a housing and each zone solenoid can be arranged with each zone clutch mechanism. The relay and the solenoid of each zone can be linked via jumper connections, the jumper connections configurable based on whether the zone is an infeed zone, an intermediate zone, and an outfeed zone to determine whether space or no space energizes a respective solenoid for zone operation. The relays can be contained in a housing to be mounted on a frame of each zone as a control module for each zone. The housings can be equipped with quick connect couplings and connectors to facilitate linking the control modules of the various zones together.
In another embodiment, the infeed and outfeed conveyor control modules can be additionally linked to one or more PLCs to interface with systems other than the accumulation conveyor control system, e.g., devices upstream of the infeed conveyor or downstream of the outfeed conveyor and the like.
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Dickinson Wright PLLC
Jervis B. Webb Company
Sharma Rashmi
Valenza Joseph E.
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