Stepping Relay Fuel Dispenser Security Interlock
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel theft from service stations and private vehicles is prevalent due to the ability of thieves to bypass credit card authorization systems and access fuel dispensers without payment, necessitating a system to detect access door openings and disable fuel pumps until authorized reset.
Innovation Solution
A security device featuring a stepping relay with contacts between the power source and fuel pump, triggered by door interlock switches, which opens the contacts when the access door is opened, preventing fuel dispensing until a reset switch is activated, ensuring power is restored to the relay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the access door is opened to allow employee access for maintenance or refilling, then the fuel pump can be accessed and serviced, but thieves can also open the door to steal fuel by bypassing the authorization system
Solution Approach 1:
A door interlock switch is introduced as an intermediary between the access door and the fuel pump authorization system. When the access door is opened, the switch detects this and automatically disables the fuel pump authorization, preventing thieves from stealing fuel while allowing employees to access the dispenser for legitimate purposes.
Solution Approach 2:
The door interlock switch provides real-time feedback to the authorization system about the state of the access door. When the door is opened, this feedback signal immediately triggers the disabling of the fuel pump authorization, creating a closed-loop security system that responds dynamically to access attempts.
2Device complexity
If a simple door switch is used to detect access door opening, then the system is easy to implement, but thieves can bypass it by jimmying the lock or prying open the door without triggering the switch
Solution Approach 1:
The door interlock switch is pre-configured in the circuitry before any theft attempt occurs. It is mechanically linked to the access door assembly such that any opening action—whether legitimate or attempted—will trigger the switch. This preliminary setup ensures that the security response is automatic and cannot be easily circumvented by mechanical forcing.
3Object-affected harmful factors
If the fuel pump is disabled immediately when the access door is opened, then theft is prevented, but legitimate employees cannot access the fuel pump for maintenance or refilling operations
Solution Approach 1:
The authorization system dynamically changes its state based on the position of the access door. When the door is closed, the system is in a permissive state allowing fuel dispensing. When the door is opened, the system automatically transitions to a disabled state. This dynamic behavior allows the same system to serve both security and operational needs without contradiction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents unauthorized fuel dispensing by ensuring the fuel pump remains disabled when the access door is opened, requiring a valid reset to re-enable fuel delivery, thereby reducing theft from fuel dispensers.
Implementation Method 1
a stepping relay with contacts arranged in series between a source of power and a fuel pump such that when the contacts are open, no fuel can be dispensed. The stepping relay is triggered by one or more door interlock switches
Data Source
AI summary
A security device for a fuel dispenser includes a stepping relay having contacts arranged in series between a source of power and a fuel pump such that when the contacts are open, no fuel can be dispensed. The stepping relay is triggered by one or more door interlock switches that are powered by the fuel pump side of the contacts such that, when an access door is opened, the relay is triggered and the door interlock switches are no longer powered, hence, disabled. Therefore, a reset switch that is constantly powered is interfaced to trigger the stepping relay to close the contacts and allow fuel to be dispensed. Preferably, the reset switch is either remotely located or has a security feature.