Method for stopping a reciprocating compressor, and reciprocating compressor of a refrigeration device, of an air conditioning device, or of a heat pump, and refrigeration device, air conditioning device, or heat pump having said reciprocating compressor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reciprocating compressors in household refrigeration appliances experience noise and vibration issues during shutdown due to uneven load application and mechanical inertia, leading to potential impacts within the compressor capsule.
Innovation Solution
A method utilizing a brushless BLDC motor with windings, where the motor is slowed down by a predetermined decreasing frequency function, ensuring controlled coasting without abrupt load changes, and utilizing a non-linear frequency curve to manage the motor's deceleration and acceleration, thereby minimizing vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the motor is actively braked by applying a rotating field during shutdown, then the stopping time is reduced, but the motor experiences abrupt load changes causing vibration and impact
Solution Approach 1:
The patent applies dynamic control of the rotating field frequency during motor shutdown, using a non-linear decreasing function that adapts the braking torque throughout the deceleration process. This dynamic approach allows the system to maintain controlled deceleration while avoiding the abrupt load changes that cause vibration and impact, resolving the contradiction between fast stopping and smooth operation.
Solution Approach 2:
The patent changes the parameter of rotating field frequency from constant to non-linearly decreasing during the shutdown process. By continuously adjusting the frequency parameter according to a predetermined non-linear decreasing function, the system achieves both reduced stopping time and minimized vibration through optimized torque control throughout the deceleration phase.
2Object-generated harmful factors
If the motor is allowed to coast without active braking, then vibration and impact are reduced, but the stopping time increases
Solution Approach 1:
The patent applies partial active braking through a non-linear decreasing rotating field frequency that provides just enough torque to control the coasting process without causing excessive vibration. This partial action approach achieves a balance between the benefits of coasting (reduced vibration) and the need for controlled stopping time, avoiding both complete coasting and aggressive braking.
3Device complexity
If a linear frequency decrease is used during shutdown, then the control is simple, but the motor may still experience vibrations due to uneven load distribution
Solution Approach 1:
The patent transitions from simple linear frequency control to dynamic non-linear frequency control during shutdown. The non-linear decreasing function adapts the braking torque to match the motor's load characteristics throughout deceleration, effectively reducing vibration while maintaining manageable control complexity through a predetermined functional relationship.
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 and vibration during compressor shutdown, ensuring a quiet and controlled stop, delaying the motor's stop and reducing the risk of impact, resulting in a low-vibration coasting process compared to de-energized motors.
Implementation Method 1
energizing the windings with a drive current at a frequency, wherein the frequency follows a predetermined decreasing function
Implementation Method 2
deceleration of the motor due to a load predominates over acceleration of the motor due to the current supply
Data Source
Figure 1~4
AI summary
A method for stopping a reciprocating compressor of a refrigeration device, air conditioning device or a heat pump, wherein the compressor has a brushless motor with windings, has the method steps: - rotating (41) of the motor at an operating rotational speed; - obtaining (42) of a signal for stopping; and - performing (44) of an assisted running-down operation by way of energizing of the windings with a drive current at a frequency, wherein the frequency proceeds in accordance with a predefined decreasing function (32), and wherein slowing of the motor on account of a load predominates over a compression cycle in comparison with an acceleration of the motor on account of the energization.