Condensate Drain Pump Eccentric Coupling Noise Reduction
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Solution Overview
Problem
Synchronous motor-driven condensate drain pumps in household appliances suffer from high noise levels during starting and steady operation due to the eccentric-teeth coupling device, which causes continuous impacts and discontinuous contact between the driving tooth and impeller.
Innovation Solution
Incorporating elastic means that create rubbing friction between the impeller and a matching surface to reduce the relative speed of the eccentric teeth during starting, ensuring continuous contact and reducing noise, while keeping the impeller axially fixed to prevent vibrations and noise in full-load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an eccentric-teeth coupling device is used to allow free travel during starting, then the motor can reach synchronous speed before coupling the load, but continuous impacts between teeth generate high noise during starting and operation
Solution Approach 1:
A viscous damping element is introduced as an intermediary between the driving tooth and driven tooth of the eccentric-teeth coupling device. This damping element absorbs impact energy during tooth engagement, significantly reducing the noise generated during starting and steady operation while maintaining the coupling device's ability to allow free travel and achieve synchronous speed.
2Adaptability or versatility
If the impeller is allowed to detach from the driving tooth during operation, then the coupling device can accommodate speed variations, but discontinuous contact generates noise in steady state
Solution Approach 1:
The viscous damping element serves as a mediator that maintains continuous contact between the driving tooth and driven tooth while accommodating speed variations. The damping material provides continuous damping action, eliminating noise during steady operation while preserving the coupling device's adaptability to speed changes.
3Object-generated harmful factors
If the elastic element presses the impeller assembly against the matching surface, then friction reduces relative speed of teeth during free travel and reduces impact noise, but the same friction ensures continuous contact during operation to avoid detachment noise
Solution Approach 1:
The elastic element modifies the contact parameters between the impeller assembly and matching surface by applying axial pressure. This creates controlled friction that reduces the relative speed of teeth during free travel, thereby reducing impact noise during starting. The same friction mechanism ensures continuous contact during operation, preventing detachment noise.
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 effectively reduces noise during both starting and steady operation by minimizing impact forces and maintaining continuous contact between transmission elements, resulting in a quieter and more stable pump performance.
Implementation Method 1
elastic means acting on said impeller in the direction of the rotation axis so as to define a rubbing friction between a contact surface which is integral with the impeller and a matching surface which is not integral with the impeller
Implementation Method 2
elastic means acting on said impeller in the direction of the rotation axis
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Condensate drain pump (1) with reduced noise comprising: a permanent-magnet synchronous motor (13) provided with a rotor (7) rotating with respect to a rotation axis (x); an impeller (3) coaxially rotating with respect to the rotor (7) and coupled thereto by an eccentric-teeth coupling device (8); elastic means (5) arranged to keep the impeller assembly in a sliding position against a matching element.