Electromechanical Push-to-Close Latch With Cam-Actuated Pawl
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Solution Overview
Problem
Existing electromechanical push to close latches experience wear and erratic operation due to timing and length issues with electric activation signals, especially when the operator is out of sight, and are limited by the size and strength of the latch housing.
Innovation Solution
An electromechanical push to close latch with a spring-loaded, blade or bar-shaped pawl that is remotely operated using a DC motor coupled through a gearbox to a cam, allowing controlled retraction and extension, and a reconfigurable housing for various installations, with position sensors for precise control and feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electromagnet or solenoid is used to retract the pawl, then the latch can be operated remotely, but the pawl may bind and the solenoid cannot retract it smoothly, causing wear and erratic operation
Solution Approach 1:
The cam is designed to preliminarily guide the pawl along a controlled path during retraction, ensuring the pawl is properly positioned and oriented before the final latching action occurs. This preliminary guidance prevents binding and ensures smooth operation throughout the retraction sequence.
Solution Approach 2:
The cam acts as an intermediary mechanism between the solenoid and the pawl, translating the solenoid's linear motion into a controlled rotational and linear movement of the pawl. This intermediary action ensures the pawl retracts smoothly without binding against the striker.
2Volume of stationary object
If the latch housing size is limited, then the installation space is reduced, but the capacity and strength of the electromagnetic activator are reduced
Solution Approach 1:
The patent replaces a portion of the direct electromagnetic-pawl interaction with a mechanical cam mechanism. The solenoid only needs to move the cam a short distance, and the cam's mechanical geometry amplifies this motion to achieve full pawl retraction. This substitution allows a smaller, weaker solenoid to effectively operate the latch within a compact housing.
Solution Approach 2:
The cam mechanism introduces dynamic motion transformation, converting the solenoid's simple linear reciprocating motion into a complex path that guides the pawl through its retraction and latching sequence. This dynamic mechanism allows the system to achieve high mechanical advantage with minimal solenoid travel distance, enabling compact housing design.
3Strength
If a tapered ramp-ended pawl is used, then the latching force is improved, but the pawl encounters binding forces during retraction when the operator is out of sight
Solution Approach 1:
The cam preliminarily positions and orients the pawl before it engages the striker during retraction. This preliminary action ensures the pawl's tapered surface is properly aligned, allowing it to slide smoothly along the striker's surface rather than binding, while still maintaining the latching force when engaged.
Solution Approach 2:
The cam mechanism creates a periodic motion sequence during retraction: first guiding the pawl backward, then rotating it to the proper orientation, and finally allowing it to engage the striker. This periodic breakdown of the retraction motion ensures the tapered pawl surface remains properly aligned throughout the sequence, preventing binding.
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
The solution provides smooth and controlled operation of the pawl, ensuring reliable latching and unlocking functions, even in remote operations, and accommodates different installation sizes and orientations, reducing wear and improving operational reliability.
Implementation Method 1
a spring biased to force the pawl to the extended position
Implementation Method 2
A DC electric motor is coupled through a gearbox to rotate a cam which is connected to retract the pawl into the pawl housing
Implementation Method 3
An electric DC motor is coupled through a gearbox to rotate a cam
Data Source
AI summary
An electromechanical push to close latch has a pawl positioned for linear movement in a housing, with the pawl being biased to the outward extended position. An electric motor operates a cam to change the position of the pawl thereby retracting it into the housing. An electronic circuit board controls the operation of the electric motor under the direction of an outside control signal. The circuit board also senses the position of the pawl to stop the operation of the motor when the pawl is fully retracted. The pawl mounting can be reconfigured for the pawl to extend and thereby operate in a plurality of selectable directions.