Double Break Disconnect Switch Cam Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High voltage switches face challenges in rotational movement due to ice buildup and debris, requiring large forces for opening and closing, and existing mechanisms like beveled gears increase friction and operational difficulties as blade diameter increases.
Innovation Solution
A double break disconnect switch with a unique cam mechanism and offset blade bearings that use the blade's weight to maintain disengagement and reduce friction, allowing for easier operation with less force, and a helical camming surface to minimize wear and optimize rotational torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If beveled gear or cam mechanisms are used for rotational movement of the switch blade assembly, then the switch can achieve contact pressure development and release for opening and closing, but large forces are required to initially open or finally close the switch due to ice buildup and debris
Solution Approach 1:
The patent employs a spherical cam surface that rotates about a vertical axis to drive the blade assembly. The curved spherical geometry provides smooth rotational movement and gradual contact pressure development, reducing the peak forces required compared to traditional beveled gear mechanisms. The spherical cam's geometry allows for continuous, progressive motion that overcomes ice buildup and debris more effectively.
Solution Approach 2:
The switch blade assembly is designed with dynamic characteristics that allow it to swing open and closed through a macro motion arc. The blade can rotate significantly (greater than 10 degrees) to move from engaged to disengaged positions, providing dynamic movement that helps overcome static friction from ice and debris. The system transitions from static to dynamic operation to facilitate reliable switching.
2Reliability
If round tubular blades with large diameter are used for high current ratings, then the switch can handle higher currents, but friction increases making operation more difficult
Solution Approach 1:
The patent introduces a vertical dimension to the cam mechanism by rotating the spherical cam about a vertical axis rather than using horizontal beveled gears. This vertical rotation dimension allows the large-diameter blade to be driven more efficiently, reducing friction. The vertical cam rotation creates a different mechanical advantage that scales better with blade diameter.
Solution Approach 2:
The patent changes the geometric parameters of the cam mechanism, specifically using a spherical cam with a radius that is a significant fraction of the blade radius (e.g., 0.25 to 0.5 times the blade radius). This parameter relationship optimizes the mechanical advantage and reduces friction for large-diameter blades handling high currents.
3Device complexity
If the hinge axis is positioned on the blade surface, then the structure is simpler, but the blade cannot effectively use its weight to maintain disengagement and reduce friction
Solution Approach 1:
The patent positions the horizontal hinge axis offset from the blade's longitudinal centerline, creating an asymmetric configuration. This offset positioning allows the blade's weight to create a gravitational moment that naturally maintains disengagement between blade and jaw contacts. The asymmetric hinge placement converts the blade's weight from a neutral or harmful factor into a useful force that reduces friction and facilitates operation.
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 enables the switch to operate with substantially less force, maintain alignment for optimal contact life, and reduce friction and jamming risks, even at higher current ratings, ensuring reliable and efficient operation.
Implementation Method 1
This mechanism uses a unique cam to rotate the blade about a hinge axis L
Implementation Method 2
The camming mechanism is profiled to give maximum rotational torque to the blade as it compresses the contact fingers
Implementation Method 3
the blade bearings are offset from the blade center of gravity so as to use the blade's weight to keep the blade in the position of disengagement with the break jaw contacts
Implementation Method 4
these bearings are very small in diameter which reduces friction to make the switch operate with substantially less force
Implementation Method 5
A further advantage of the new design is structure that allows the blade to move vertically within pivot points to better align the blade contacts with the break jaw contacts
Data Source
AI summary
A double break disconnect switch with a novel drive mechanism that swings the blade open and closed in a conventional manner but the rotation with respect to its longitudinal axis is unique. This mechanism uses a unique cam to rotate the blade about a hinge axis. The blade bearings are of very small diameter to reduce friction and are offset from the blade center of gravity so as to use the blade's weight to keep the blade in disengagement with the break jaw contacts when the switch is opened. The blade bearings are not around the diameter of the blade, the friction does not increase as current rating increases. A camming mechanism is profiled to give maximum rotational torque to the blade as it compresses the contact fingers as the switch closes to its final position.