Elevator Governor Swing Jaw Automatic Reset Mechanism
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Solution Overview
Problem
Existing elevator systems with centrifugal governors require manual resetting of the tripping lever after an overspeed condition, leading to potential continued operation during the engagement process due to slow radial movement of flyweights, which may not effectively stop the elevator car or counterweight.
Innovation Solution
A governor assembly with a swing jaw biased into a tripped position, featuring a tripping lever and ratchet disc configuration that automatically resets upon reverse rotation, ensuring efficient engagement and disengagement to prevent overspeed conditions, including a remote tripping assembly for automated operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tripping lever is manually reset after an overspeed condition, then the governor can be reused, but the elevator system experiences downtime and requires mechanic intervention
Solution Approach 1:
The governor assembly performs self-resetting through the automatic return mechanism. When the sheave rotates in the reverse direction (during normal elevator operation), the cam surface automatically moves the swing jaw back to the engaged position, eliminating the need for manual intervention and reducing downtime
2Reliability
If the flyweights move radially outward slowly during overspeed condition, then the governor mechanism activates, but the swing jaw may contact and deflect from the end of a tooth on the ratchet disc, allowing overspeed to continue
Solution Approach 1:
The swing jaw is pre-biased into the tripped position through a spring mechanism before the overspeed condition occurs. This preliminary positioning ensures that when the tripping lever releases the swing jaw during overspeed, the jaw is already in the correct position to immediately engage the ratchet disc tooth, eliminating the delay caused by slow radial movement of flyweights
Solution Approach 2:
Instead of relying on the slow radial outward movement of flyweights to drive the swing jaw into the tripped position, the invention inverts the approach by using a spring to pre-position the swing jaw in the tripped position and using the rotation direction change to maintain or restore engagement, ensuring immediate and reliable ratchet disc engagement
3Speed
If the swing jaw is biased into the tripped position, then immediate engagement with the ratchet disc is achieved, but the mechanism requires a reset mechanism to return to normal operation
Solution Approach 1:
The reset mechanism utilizes the natural reverse rotation of the sheave during normal elevator operation to automatically return the swing jaw to the engaged position. The cam surface on the sheave interacts with the swing jaw to perform the resetting action, eliminating the need for complex external reset mechanisms or manual intervention
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 immediate and effective engagement to stop the elevator during overspeed conditions and automatically resets, reducing the time required to halt the elevator car, enhancing safety and operational efficiency.
Implementation Method 1
The swing jaw is biased into the tripped position
Implementation Method 2
The angular velocity of the rotating masses results in a centrifugal force acting to propel the masses away from the sheave axis of rotation
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
A governor assembly (16) is provided including a sheave (18) rotatably mounted on a shaft and a ratchet disc (30) mounted on the shaft. Rotation of the ratchet disc (30) is restricted. An overspeed assembly (40) includes a swing jaw (42) mounted to the sheave (18). The swing jaw (42) is movable between a normal position and a tripped position. The swing jaw (42) is biased into the tripped position. When the swing jaw (42) is in the tripped position, rotation of the sheave (18) in a first direction is restricted. A tripping lever (44) is pivotally mounted to the sheave (18) and is configured to cooperate with the swing jaw (42). Rotation of the sheave (18) in a second, opposite direction is configured to automatically move the swing jaw (42) against its bias to the normal position.