Low-Voltage DC Access Control Device for Push Bar Exit
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Solution Overview
Problem
Existing push bar exit devices for commercial buildings are costly to operate and maintain, particularly in terms of power and maintenance requirements, as they often require connection to utility power sources.
Innovation Solution
A low-voltage, direct current apparatus comprising a mounting bar, a latch with a locking lever, and an actuator that includes a motor, lead screw, and nut to move the locking lever between locked and unlocked positions, powered by a source such as a battery operating at less than 12 volts, allowing for efficient and cost-effective operation without the need for utility power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If push bar exit devices are equipped with standard actuators and power sources, then the door can be securely locked and unlocked, but the power consumption and maintenance costs increase significantly
Solution Approach 1:
The patent changes the voltage parameter from standard high voltage to low voltage (less than 12V DC), which reduces power consumption while maintaining the locking function. The motor is specifically designed to operate at this reduced voltage level, transforming the energy parameter to achieve both reliability and energy efficiency.
Solution Approach 2:
The spring mechanism provides self-service by automatically returning the locking lever to the locked position when the motor retracts the nut. This eliminates the need for additional power to maintain the locked state, reducing overall power consumption while ensuring reliable door security.
2Power
If push bar exit devices are connected to utility power sources, then sufficient power is available for operation, but installation complexity and maintenance requirements increase
Solution Approach 1:
The patent extracts the power source requirement from the utility power infrastructure and replaces it with an integrated low-voltage power source (battery) within the device itself. This eliminates the need for external power connections, reducing installation complexity while providing sufficient power for the motor actuator.
Solution Approach 2:
The low-voltage DC motor serves multiple functions: it can be powered by batteries (portable operation) or connected to low-voltage power sources (fixed installation), making the device universally applicable in various installation scenarios without requiring complex power infrastructure.
3Force
If high-voltage actuators are used in push bar exit devices, then strong actuating force is achieved, but the cost of operation and maintenance increases
Solution Approach 1:
The patent replaces high-voltage electrical actuation with a low-voltage motor combined with a spring-mechanical system. The motor provides initial actuating force to move the locking lever, and the spring maintains the locked position, eliminating the need for continuous high-voltage power and reducing operational costs.
Solution Approach 2:
The motor operates periodically rather than continuously - it activates only when needed to transition between locked and unlocked states. The spring then maintains the position without additional power input, reducing overall energy consumption and operational costs compared to continuous high-voltage actuation.
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
This solution reduces the cost of operation and maintenance by enabling the installation and operation of push bar exit devices using low-voltage direct current, eliminating the need for additional power sources and allowing for installation in locations without utility power, thereby lowering installation costs and enhancing operational efficiency.
Implementation Method 1
The motor may be configured to rotate the lead screw in a first direction to push the nut against the locking lever
Implementation Method 2
The actuator may comprise a lead screw, a nut, and a motor. The nut may be threaded onto the lead screw and configured to engage the locking lever
Implementation Method 3
A spring may be configured to return the locking lever to the locked position if the motor retracts the nut from the locking lever
Data Source
AI summary
A low-voltage, direct current apparatus for controlling a door. The apparatus may comprise a mounting bar configured to be coupled to the door and a latch coupled to the mounting bar. The latch may comprise a locking lever, and an actuator may be configured to move the locking lever between a locked position in which the locking lever prevents movement of the latch to an unlocked position in which the locking lever allows movement of the latch.