Asynchronous Motor Coupling for Lift Drive Wear Reduction
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Solution Overview
Problem
Existing load lifting devices face challenges with uneven load distributions causing excessive wear on drives, requiring frequent sensor maintenance and varying service lives due to differing load profiles, especially with high loads.
Innovation Solution
Mechanical coupling of two asynchronous motors via synchronous shafts and counterweights, allowing torque and speed adaptation to ensure even load distribution and synchronization without position sensors, and using guide rollers for stable cabin alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor-based control is used to detect tilting position and compensate for load distribution, then the lift cabin can be raised and lowered consistently, but the control effort increases and sensor maintenance becomes essential
Solution Approach 1:
The patent removes the sensor-based control system entirely, extracting the problematic detection and control components. Instead of using sensors to detect tilting position and actively compensate for load distribution, the system relies on passive mechanical balance through counterweights and gravity, eliminating the need for complex control efforts and sensor maintenance.
Solution Approach 2:
The lift cabin system becomes self-regulating through the counterweight mechanism. The counterweights automatically balance the load distribution without external control intervention. The system uses its own weight and gravity to maintain equilibrium, eliminating the need for active sensor-based control and compensation mechanisms.
2Adaptability or versatility
If heavy loads are distributed unevenly within the lift cabin, then the drives are exposed to very different loads, but this causes drives to have very different service lives
Solution Approach 1:
The patent introduces counterweights that automatically counterbalance uneven load distributions in the lift cabin. The counterweights are positioned and sized to offset the gravitational force of varying loads, ensuring that the drives experience more uniform torque requirements regardless of load distribution. This mechanical balancing act protects the drives from extreme torque variations and extends their service life.
Solution Approach 2:
The system changes the operational parameters of the drives by using counterweights to modify the torque profile. Instead of the drives experiencing full variation in load forces, the counterweights pre-compensate for these variations, changing the effective torque parameters that the drives must handle. This parameter modification ensures more uniform wear and extends drive service life.
3Adaptability or versatility
If four separate drive rollers are used with independent drives, then the system can handle varying loads, but the drives are exposed to different load profiles and have different service lives
Solution Approach 1:
The patent merges the drive system into two unified drive units, each responsible for two counterweights. This consolidation ensures that both drives experience identical load profiles since they both handle the same total counterweight mass. The merging of drives eliminates the reliability issue of uneven wear by ensuring symmetric load distribution across all drive components.
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 reduces drive wear, enables low-maintenance operation, and ensures even load distribution and synchronized movement of the lift cabin, reducing the need for complex control systems and maintaining operational stability across varying loads.
Implementation Method 1
two of the four drive rollers are connected to one another in a rotationally fixed manner via a common synchronous shaft
Implementation Method 2
the two asynchronous motors are mechanically coupled to one another via the elevator car and also via the two counterweights
Implementation Method 3
each of which is connected to an asynchronous motor as a drive
Implementation Method 4
the slip characteristic of asynchronous motors leads to a reduction in the nominal speed and an increase in the torque of the asynchronous motors as the load increases
Implementation Method 5
the lift cabin can be displaced along a vertical guide
Data Source
Figure 1
AI summary
The invention relates to a device for hoisting loads, having a lift car (9), which can be displaced along a vertical guide (10, 11) and is connected to counterweights (5, 6) via four traction means (7, 8), which are each fastened to a load-receiving point (12) of the lift car (9), the traction means (7, 8) being drive-connected to a drive in each case via a drive pulley (14a, 14b, 14c, 14d) in order to displace the lift car (9) and the counterweights (5, 6). According to the invention, in order to allow operation which protects the drives and requires little maintenance, even in the case of large loads distributed unevenly in the lift car, in each case two of the four drive pulleys (14a, 14b, 14c, 14d) are connected to one another for conjoint rotation via a common synchronous shaft (3, 4), which is drive-connected to an asynchronous motor (1, 2) as the drive, and two counterweights (5, 6) are provided, each of which is connected to two traction means (7, 8) assigned to separate synchronous shafts (3, 4).