Compressor Crankcase Heating Using Stator Windings and Temperature Feedback
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Solution Overview
Problem
Compressor crankcase heating systems face inefficiencies due to continuous heating when the compressor is off, leading to wasted energy and insufficient lubrication during cold starts, which can cause bearing wear and liquid flood-back issues.
Innovation Solution
A compressor crankcase heating control system that uses a stator of an electric motor to heat the crankcase, with a processor-controlled module managing the heating based on ambient and compressor temperatures, and a lower voltage for efficient heating, turning heating on or off as needed to prevent cold starts and liquid migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous crankcase heating is applied when the compressor is off, then the lubricant temperature is maintained and bearing wear is prevented, but energy consumption increases and efficiency decreases
Solution Approach 1:
The patent implements periodic crankcase heating by using the stator winding to apply heat only during specific intervals when the compressor is off and lubricant temperature drops below a threshold, rather than continuous heating. This resolves the contradiction by providing intermittent heating that prevents bearing wear while minimizing energy consumption.
Solution Approach 2:
The patent employs a temperature sensor to monitor crankcase temperature and a control module that activates heating only when the temperature falls below a predetermined threshold. This feedback mechanism ensures heating is applied only when necessary to prevent bearing wear, avoiding unnecessary energy consumption during normal temperature conditions.
2Reliability
If crankcase heating is applied at all times, then lubricant viscosity is maintained and insufficient lubrication is prevented, but energy waste occurs and system efficiency decreases
Solution Approach 1:
The system applies heating periodically based on temperature monitoring, using the stator winding to heat the crankcase only when lubricant temperature drops and viscosity increases to problematic levels. This periodic approach maintains adequate lubrication while eliminating continuous energy waste.
Solution Approach 2:
The patent changes the heating parameter from continuous operation to threshold-based intermittent operation. The control module monitors temperature and activates heating only when the temperature parameter falls below a predetermined threshold, optimizing the balance between lubrication sufficiency and energy efficiency.
3Use of energy by moving object
If the compressor starts with low crankcase temperature, then energy consumption during operation is reduced, but bearing wear and liquid flood-back occur due to insufficient lubrication
Solution Approach 1:
The patent applies preliminary heating action to the crankcase using the stator winding before the compressor starts operating, when temperature sensors detect low lubricant temperature. This preliminary heating ensures adequate lubrication is in place before startup, preventing bearing wear and liquid flood-back while allowing the compressor to operate at optimal temperature.
4Use of energy by stationary object
If a dedicated heating element is used for crankcase heating, then heating efficiency is high, but device complexity and cost increase
Solution Approach 1:
The patent makes the stator winding multi-functional by using it both for motor operation during compressor running and for crankcase heating when the compressor is off. This eliminates the need for a separate dedicated heating element, reducing device complexity and cost while maintaining heating efficiency through the existing high-power stator winding.
Solution Approach 2:
The patent merges the heating function with the motor stator winding, combining two functions (motor operation and crankcase heating) into a single component. This consolidation reduces the number of separate parts, simplifies the system, and lowers cost while maintaining effective heating capability.
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 energy consumption and increases efficiency by only heating the crankcase when necessary, preventing damage from cold starts and minimizing liquid migration, thus enhancing compressor performance and longevity.
Implementation Method 1
A compressor crankcase heating control system uses a stator of an electric motor to heat the crankcase
Data Source
AI summary
A first switching device includes a first and second inputs connected to first and second power lines, respectively, the first and second power lines for receiving a first voltage. The first switching device selectively connects and disconnects the first and second inputs to and from first and second nodes, respectively. A second switching device includes a third input connected to the first node, includes a fourth input connected to a third power line, and includes a first output connected to a first end of a stator winding. A third switching device includes a fifth input connected to the second node and includes a sixth input connected to a fourth power line, the third and fourth power lines for receiving a second voltage that is less than the first voltage. The third switching device further includes a second output connected to a second end of the stator winding. A compressor crankcase heating control module controls the second and third switching devices to control compressor crankcase heating.