Scroll Compressor Wrap Offset for Thermal Expansion
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Solution Overview
Problem
The existing scroll compressors experience compression loss, leakage, and excessive frictional loss due to thermal expansion differences between the fixed and orbiting wraps, leading to interference and abrasion, which affects the compressor's efficiency and reliability.
Innovation Solution
The introduction of an offset portion on the fixed and/or orbiting wraps near the suction chamber, within a specific range of ±30° from the suction completion point, to prevent interference and maintain optimal wrap thickness, thereby reducing thermal expansion-induced gaps and frictional losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the fixed wrap is made with uniform thickness to ensure stable compression chamber formation, then the compression chamber can be stably formed, but thermal expansion causes the fixed wrap to contract towards the central region, leading to interference with the orbiting wrap and compression loss
Solution Approach 1:
The patent applies local quality by varying the thickness of the fixed wrap along its length. Specifically, the fixed wrap has a greater thickness at the suction chamber side and a smaller thickness at the discharge chamber side. This non-uniform thickness distribution compensates for the differential thermal expansion that occurs when the compression chamber is exposed to high-temperature discharged refrigerant, preventing the fixed wrap from contracting too much towards the central region and interfering with the orbiting wrap.
2Strength
If the fixed wrap near the suction chamber is designed with sufficient thickness to maintain structural integrity, then structural stability is improved, but thermal transformation causes excessive contact with the orbiting wrap, increasing frictional loss and abrasion
Solution Approach 1:
The patent implements local quality by designing the fixed wrap with a thickness that varies along its length. The wrap has a greater thickness at the suction chamber side where structural integrity is needed, and a smaller thickness at the discharge chamber side where thermal expansion is most severe. This gradient thickness distribution maintains structural strength while reducing excessive contact and frictional loss with the orbiting wrap in the thermally affected region.
3Stability of the object's composition
If the fixed scroll plate portion is coupled to the discharge cover to ensure stable support, then the fixed scroll is stable, but the plate portion is entirely influenced by discharge temperature causing thermal expansion that transforms the fixed wrap shape
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness distribution in the fixed wrap. The wrap has a greater thickness at the suction chamber side and a smaller thickness at the discharge chamber side. This design allows the fixed scroll plate portion to remain stable and supported by the discharge cover, while the varying wrap thickness compensates for the thermal expansion of the plate portion, preventing excessive transformation of the fixed wrap shape.
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 effectively minimizes compression losses, prevents refrigerant leakage, and reduces frictional losses between the wraps, enhancing the reliability and efficiency of the scroll compressor by maintaining proper alignment and reducing thermal expansion-induced stresses.
Implementation Method 1
the fixed scroll is exposed to a refrigerant discharge temperature as a plate portion which forms a rear surface thereof is coupled to an inner space of a casing or a discharge cover or a high and low pressure separation plate. As the rear surface of the fixed scroll is exposed to a refrigerant discharge temperature, the plate portion of the fixed scroll is entirely influenced by the refrigerant discharge temperature to be thermally-expanded.
Implementation Method 2
a fixed wrap, provided on one side surface of the plate portion of the fixed scroll and forming the compression chamber, is not entirely influenced by a refrigerant discharge temperature. More specifically, a part of the fixed wrap near a suction chamber is influenced by a suction temperature, a part of the fixed wrap near an intermediate pressure chamber is influenced by an intermediate compression temperature, and a part of the fixed wrap near a discharge chamber is influenced by a discharge temperature. That is, the fixed wrap has a different thermal expansion rate according to a region. As the plate portion of the fixed scroll is more thermally-transformed than the fixed wrap, the fixed wrap is transformed in a contracted shape.
Data Source
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AI summary
A scroll compressor comprises: an orbiting scroll (33) having an orbiting wrap (332), and which performs an orbiting motion; a fixed scroll (32) having a fixed wrap (323) with a fixed plate portion (321) having an inlet (324) and an outlet (325) to form a compression chamber (V) of a suction chamber, an intermediate pressure chamber and a discharge chamber, by being engaged with the orbiting wrap; and an offset portion (323b, 332b) provided in at least one portion of the fixed wrap (322) or the orbiting wrap (332) and extending an interval between the fixed wrap (322) and the orbiting wrap (332), and the offset portion is provided adjacent to the inlet (324).