Dual-Compressor Heat Pump Control for Wider Temperature Range

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Solution Overview

Problem

Existing heat pump devices face inefficiencies and limited operational range due to inadequate control over compressor operation, particularly in varying outdoor temperatures and refrigerant management.

Innovation Solution

A heat pump device with a control unit that dynamically adjusts the operation of first and second compressors based on outside temperature, heating circuit setpoint temperature, and hot gas temperature, utilizing speed limitation and pressure monitoring to optimize power usage and extend operational range.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If compressor speed is increased to expand operational range, then efficiency deteriorates due to inadequate speed control

Engineering Contradiction:
Improveoperational rangeVSAvoidefficiency
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent applies dynamics by implementing variable speed control for the compressor motor. The control unit adjusts the compressor speed dynamically based on operating conditions (temperature differences, load requirements), allowing the system to operate efficiently across a wide range of conditions rather than at fixed speeds. This resolves the contradiction by making the compressor adaptable to different operational scenarios while maintaining optimal efficiency through continuous speed optimization.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes parameter changes by modifying the compressor speed parameter in response to changing operating conditions. The control unit monitors parameters such as temperature difference between source and destination, and load requirements, then adjusts the compressor speed accordingly. This enables the system to expand its operational range while maintaining efficiency by continuously optimizing the speed parameter based on real-time conditions.

Inventive Principle:
Principle #35Parameter changes

2Power

If dual-compressor operation is implemented to increase power output, then device complexity increases

Engineering Contradiction:
Improvepower outputVSAvoidcompressor control system
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the compression function into two separate compressors that can operate independently or in combination. This allows the system to achieve higher power output when needed by activating both compressors, while maintaining simpler operation by using only one compressor during lower demand periods. The control unit manages the segmented compressor operations based on load requirements, resolving the contradiction between power output and system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements universality by designing a control unit that can manage multiple operating modes (single compressor, dual compressors, different speed ranges) through a single integrated control system. The control unit universally handles all compression scenarios, adjusting its behavior based on power requirements. This multi-functional approach allows the system to achieve high power output when necessary while avoiding the need for separate control systems for different operating modes, thus resolving the complexity issue.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If compressor speed is limited to prevent damage, then productivity decreases

Engineering Contradiction:
Improvecompressor protectionVSAvoidheating/cooling output
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies dynamics by implementing dynamic speed limitation that adapts to operating conditions. Rather than imposing a fixed speed limit on the compressors, the control unit dynamically adjusts the maximum allowable speed based on factors such as temperature differences, pressure conditions, and load requirements. This allows the compressors to operate at higher speeds when conditions permit (maintaining productivity) while still providing protection when conditions warrant speed reduction (maintaining reliability).

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent utilizes parameter changes by modifying the speed limitation parameter in response to changing operating conditions. The control unit monitors parameters such as temperature difference, pressure ratio, and load level, and adjusts the compressor speed limit accordingly. When conditions are favorable, the speed limit is relaxed to maximize productivity; when conditions deteriorate, the speed limit is reduced to protect the compressors. This dynamic parameter adjustment resolves the contradiction between reliability and productivity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2894417B1Heat pump device
Publication Date: 2018.03.14 STIEBEL ELTRON GMBH & CO KG
  • EP2894417B1 patent drawingFigure 1
  • EP2894417B1 patent drawingFigure 2
  • EP2894417B1 patent drawingFigure 3~4

AI summary

The invention relates to a heat pump device comprising a condenser, an evaporator, an electronic expansion valve, a compressor unit, and a control unit. The compressor unit has a first and a second compressor connected in series. The control unit serves to control the evaporator, the condenser, the expansion valve, and the compressor unit. The control unit is also configured to control the operation of the first and/or second compressor. Furthermore, the control unit includes a compressor switching unit that outputs a signal activating the first compressor, the second compressor, or both the first and second compressors depending on an outside temperature, a heating circuit setpoint temperature, and/or a hot gas temperature.