Elevator Rope Tension Control via Locking Pulleys
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Elevator car displacement caused by loading changes poses safety risks and inefficiencies in energy consumption due to elongation of elevator ropes, especially when the main floor is the lowermost used floor, and acceleration/braking events.
Innovation Solution
The implementation of a system that locks at least two rope pulleys during loading, using pretensioned rope elements and counterweights to maintain constant tension greater than the maximum loading change, allowing for controlled movement and reduced elongation, and utilizing two or more small elevator motors to optimize energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the elevator machine is positioned at the top of the hoistway, then the elevator can serve all floors, but the rope elongation caused by loading becomes greatest when the car is at the lowermost floor
Solution Approach 1:
The patent introduces a counterweight system where a first counterweight and a second counterweight are connected via a second rope element. The counterweights compensate for the weight of the elevator car and balance the rope tension, significantly reducing rope elongation caused by loading changes. This is especially effective when the elevator car is at the lowermost floor, where the elongation problem is most severe.
Solution Approach 2:
The patent changes the physical state of the rope system by introducing pretensioning means that maintain constant tension in the rope elements. By actively controlling the tension parameters through the counterweight system and locking mechanisms, the rope elongation is minimized regardless of the car's position in the hoistway.
2Manufacturing precision
If rope pulleys are locked during loading to reduce displacement, then car displacement is minimized, but the system complexity increases
Solution Approach 1:
The patent divides the rope pulley system into multiple independently controllable units. Instead of locking the entire system at once, individual rope pulleys are locked sequentially or selectively based on loading conditions. This segmentation allows for simpler control of each individual locking action while achieving the overall goal of minimizing car displacement.
Solution Approach 2:
The patent implements preliminary locking of rope pulleys before the actual loading process begins. By pre-positioning and securing the pulleys in advance, the system prevents displacement from occurring in the first place, rather than requiring complex real-time adjustment mechanisms during loading.
3Use of energy by moving object
If multiple small motors are used instead of one large motor, then energy consumption is optimized, but the device complexity increases
Solution Approach 1:
The patent divides the single large motor function into multiple smaller motors, each responsible for specific rope elements or counterweights. This segmentation allows each motor to operate only when needed, optimizing energy consumption. The control system manages multiple independent motor units rather than one continuously operating large motor.
Solution Approach 2:
The patent implements periodic activation of motors based on actual loading requirements. Motors are engaged only during specific phases of operation (acceleration, braking, loading) and remain idle otherwise. This periodic action pattern significantly reduces overall energy consumption compared to continuous operation of a single large motor.
4Reliability
If the elevator has a leveling function to compensate for height differences, then safety is improved, but energy consumption increases due to repeated motor starts
Solution Approach 1:
The patent performs preliminary leveling compensation by locking the appropriate number of rope pulleys before the elevator car arrives at the floor. This pre-adjustment eliminates the need for repeated motor starts during the leveling process, as the car is already positioned at the correct height when it stops. The locking mechanism maintains this position without requiring active motor control.
Solution Approach 2:
The counterweight system provides passive compensation for height differences and loading changes. By balancing the forces through counterweights, the system maintains car position stability without requiring active motor intervention, thereby reducing energy consumption while maintaining safety.
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 minimizes displacement and safety risks, enables jerk-free starting, and optimizes energy use by only engaging necessary motors, reducing the size and cost of components and improving handling and installation.
Implementation Method 1
at least one pretensioning means acting on the elevator ropes
Implementation Method 2
the change in elongation of the elevator ropes caused by loading
Implementation Method 3
locking at least two rope pulleys corresponding to the elevator ropes
Implementation Method 4
the counterweight to the other end
Data Source
AI summary
An arrangement for reducing the displacement of an elevator car caused by a change in loading includes at least an elevator car configured to move up and down in an elevator hoistway and one or more counterweights, and also at least one rope element above the elevator car and at least one rope element below the elevator car and at least one pretensioner of the rope elements. The elevator car and counterweight are configured to be supported and moved via the rope elements and the pretensioner and rope pulleys, of which rope pulleys the first part are diverting pulleys, and the second part are traction sheaves. The arrangement additionally includes at least two hoisting machines. In the arrangement is a mechanism configured to lock at least two rope pulleys to be non-rotating at least during loading of the elevator car.