Friction-Driven Elevator Brake Auxiliary Drive With Automatic Reset
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Solution Overview
Problem
Existing elevator overspeed governors with electromagnets require manual resetting and are complex, costly, and visually unappealing, especially in glass elevators.
Innovation Solution
An auxiliary drive system with a friction body and pivoting mechanism, using a spring and electromagnet to automatically actuate and reset the elevator brake, minimizing the need for manual intervention and reducing electromagnet size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If an electromagnet is used to hold the friction body in the standby position, then the auxiliary drive can be automatically reset, but the electromagnet must be very large and costly to attract the component across the air gap after triggering
Solution Approach 1:
The friction body is designed to automatically return to its initial position (withdrawing from the brake bar) through its own weight and friction forces after the brake is triggered. This preliminary automatic reset action eliminates the need for a large electromagnet to pull the component back across a wide air gap, thereby reducing electromagnet size and cost while maintaining automatic reset capability
Solution Approach 2:
The system uses the friction body's own weight and the friction between the friction body and brake bar to automatically return the friction body to its standby position after triggering. This self-service mechanism reduces reliance on large electromagnets for resetting, thereby reducing electromagnet size and manufacturing costs
2Extent of automation
If a friction body with variable radius pivoting path is used, then the friction body can be pushed back closer to the electromagnet for automatic reset, but the pivoting mechanism becomes more complex
Solution Approach 1:
The friction body is designed with a pivoting mechanism where the friction body's distance from the pivot axis varies during operation. In the standby position, the friction body is farther from the axis, providing leverage for spring pressure. After triggering, the friction body moves closer to the axis, allowing it to be pushed back toward the electromagnet by friction forces, enabling automatic deactivation
Solution Approach 2:
The system changes the geometric parameter of the friction body's position relative to the pivot axis during operation. The variable radius pivoting path allows the friction body to transition between positions that optimize both the spring actuation leverage and the automatic return to electromagnet proximity, achieving automatic deactivation
3Device complexity
If the friction body is held at a constant distance from the pivot axis, then the pivoting mechanism is simpler, but the electromagnet must be larger to attract the friction body after triggering
Solution Approach 1:
The friction body's distance from the pivot axis is made variable rather than constant. This dynamic positioning allows the friction body to be closer to the electromagnet after triggering, reducing the air gap and enabling a smaller electromagnet to achieve automatic reset, while the variable radius pivoting mechanism remains manageable in complexity
4Force
If an endless rope loop speed governor is used, then the brake can be actuated with high force using relative movement, but the construction level is relatively high and the rope loop is visually disturbing in glass elevators
Solution Approach 1:
The invention extracts and eliminates the endless rope loop from the speed governor system. Instead, it uses a simplified auxiliary drive with a friction body that directly contacts a brake bar on the elevator car. This extraction removes the visually disturbing rope loop while maintaining the capability to actuate the brake with sufficient force through the friction mechanism
Solution Approach 2:
The complex mechanical system of the endless rope loop circulating through pulleys is replaced with a simpler direct-contact friction mechanism. The friction body with variable radius pivoting path directly engages the brake bar, substituting the rope loop system with a more compact and visually acceptable mechanical arrangement that maintains braking effectiveness
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
Disclosed is an auxiliary drive (1) for actuating an elevator brake (31), said drive comprising at least one friction body (10) that can be placed against a braking strip (17), a pivoting body, on which the friction body (10) is displaceably held relative to said pivoting body and pivotably held together with the pivoting body about a primary axis (2) lying outside the friction body (10), a spring element (6) and at least one electromagnet (15), in addition to a transmission member (22, 23) for transmitting a pivoting motion of the pivoting body to an elevator brake (31). The friction body (10) can be transferred from its operational-ready position on the pivoting body into its operating position on the pivoting body, and vice versa, when the spring element (6) is relaxed or compressed and the at least one electromagnet (15), in its first switched mode, holds the friction body (10) in its operational-ready position on the pivoting body and, in its second switched mode, releases the body such that said friction body (10) can be moved away from the at least one electromagnet (15) with the action of the spring element (6), into its operational-ready position on the pivoting body and can be brought into frictional contact with said braking strip (17). In the second switched state, there is an air gap between the electromagnet and a component attracted by the electromagnet, and the friction body (10), the pivoting body, the primary axis (2) and the braking strip (17) are arranged relative to one another such that the friction body (10) pivots the pivoting body, as a result of the frictional forces acting on the latter, about the primary axis (2) and closer to the braking strip (17) such that the friction body (10) is pushed back again from the braking strip (17) into a position on the pivoting body which is closer to its operational-ready position than its operating position, or which corresponds to its operating position, thereby reducing or eliminating the air gap across which the electromagnet must attract the assigned end of the rocker lever.