Variable Speed Scroll Compressor Oil Injection Control
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Solution Overview
Problem
Variable speed scroll refrigeration compressors face issues with oil injection control, leading to inefficient heat exchange and potential compressor damage due to excessive oil at high speeds and inadequate lubrication at low speeds, as existing solutions fail to precisely manage oil injection based on compressor speed.
Innovation Solution
A variable-speed scroll refrigeration compressor with an oil injection circuit featuring a movable shutter that opens at low speeds to allow oil injection into the compression volume and closes at high speeds, preventing oil injection, thereby controlling oil quantity precisely and maintaining performance across speed ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the compressor operates at high rotational speed, then productivity increases, but excessive oil enters the refrigerant gas causing heat exchange inefficiency and potential compressor damage
Solution Approach 1:
The patent implements a dynamic oil injection control system that adjusts oil supply based on compressor operating conditions. A control unit receives signals from a rotation speed detector and dynamically adjusts the oil injection valve opening degree according to the detected rotation speed and cooling capacity requirements, preventing excessive oil from entering the refrigerant gas at high speeds while ensuring adequate lubrication at low speeds
Solution Approach 2:
The system employs a feedback control mechanism where a rotation speed detector continuously monitors the compressor's rotational speed and feeds this information to the control unit. The control unit processes this feedback signal and adjusts the oil injection valve accordingly, creating a closed-loop control system that maintains optimal oil injection levels across varying operating conditions
2Loss of energy
If the compressor operates at low rotational speed, then energy consumption decreases, but insufficient oil injection degrades compressor performance and reduces lubrication
Solution Approach 1:
The control system dynamically adjusts the oil injection valve opening degree based on the detected rotation speed. At low rotational speeds, the control unit increases the valve opening to ensure sufficient oil injection for adequate lubrication, while at high rotational speeds, it reduces the opening to prevent excessive oil from entering the refrigerant gas
Solution Approach 2:
The system changes the oil injection parameter (valve opening degree) according to the rotation speed parameter. By varying the oil injection quantity as a function of rotation speed, the system maintains optimal lubrication at low speeds while preventing oil carryover at high speeds, thus resolving the contradiction between energy efficiency and reliability
3Device complexity
If a fixed oil injection system is used, then device complexity is reduced, but the system cannot adapt to varying speeds leading to either excessive or insufficient oil injection
Solution Approach 1:
The patent replaces complex mechanical oil injection control mechanisms with an electronic control system. A control unit with electronic circuits receives electrical signals from a rotation speed detector and controls an electronically actuated oil injection valve, substituting mechanical linkages and centrifugal governors with electronic sensing and control, thereby achieving high adaptability with relatively simple device structure
Solution Approach 2:
The control unit acts as an intermediary between the rotation speed detector and the oil injection valve. It receives detection signals, processes them according to predetermined control maps, and generates appropriate control signals for the oil injection valve, enabling adaptive oil injection control without direct mechanical coupling between the detection and actuation systems
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 enhances low-speed performance without compromising high-speed efficiency by ensuring optimal oil levels in the refrigerant gas, reducing oil-related inefficiencies and preventing compressor damage.
Implementation Method 1
a movable shutter, under the effect of a centrifugal force between a first release position of the oil injection means allowing injection of oil into the compression volume and a second closing position of the oil injection means preventing the injection of oil in the compression volume
Data Source
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AI summary
The invention relates to a refrigeration compressor having a sealed housing defining a suction volume and a compression volume respectively provided on either side of a body (5) contained in the housing, and an oil injection circuit adapted for injecting oil into the compression volume. The oil injection circuit includes a stopper (26) mobile under the action of a centrifugal force between a first position for injecting oil into the compression volume and a second position preventing or limiting the injection of oil into the compression volume, wherein the stopper (26) is adapted so as to move into the second position when the speed of the compressor exceeds a predetermined value.