Scroll Compressor Back Pressure Valve Fixing Structure
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Solution Overview
Problem
The control accuracy of back pressure in scroll fluid machines is reduced due to compressive stress from press-fitting the back pressure control valve, leading to inefficient compression and increased drive force requirements.
Innovation Solution
A scroll fluid machine with a back pressure control valve inserted into a communication passage, featuring a seal member in a circumferential groove on the valve and a ring member press-fitted into the passage to fix the valve, reducing compressive stress and maintaining accurate back pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the back pressure control valve is press-fitted into the communication passage, then the valve is fixed in position, but the compressive stress changes the clearance inside the valve and reduces control accuracy
Solution Approach 1:
The fixing structure is segmented into two separate components: a seal member fitted into a circumferential groove on the valve body, and a ring member press-fitted into the communication passage. This segmentation allows the seal member to provide sealing without transmitting compressive stress to the valve internals, while the ring member provides fixing functionality separately.
Solution Approach 2:
The seal member acts as an intermediary element between the valve body and the communication passage. It provides the necessary sealing function while preventing direct transmission of compressive stress from the press-fit connection to the valve's internal clearance, thus protecting the control accuracy.
2Reliability
If the back pressure control accuracy is reduced, then the back pressure cannot be maintained at a predetermined value, but this leads to reduced compression efficiency and increased drive force requirements
Solution Approach 1:
Instead of press-fitting the valve directly into the communication passage (conventional approach), the invention inverts the approach by having the seal member fitted into the valve body first, and then the ring member press-fitted into the communication passage to secure the assembly. This reversal prevents compressive stress from being applied to the valve casing.
3Strength
If the compressive stress is applied to the valve casing, then the valve is secured in place, but the clearance inside the valve changes and control accuracy deteriorates
Solution Approach 1:
The fixing mechanism is divided into two functional segments: the seal member that maintains sealing and internal clearance, and the ring member that provides the press-fit fixing strength. By separating these functions, the compressive stress required for fixing strength is not transmitted to the valve internals that require precision clearance.
Data Source
AI summary
The scroll-type compressor comprises a fixed scroll and an orbiting scroll engaged with each other; a back pressure control valve 50 inserted from the large-diameter side of the stepped-shaped pressure release passage L4 which communicates between a suction chamber H1 and a back pressure chamber H3 which applies a back pressure for pressing the orbiting scroll against the fixed scroll. The scroll-type compressor further comprises an O-ring 60 fitted in a circumferential groove 53a formed in the outer peripheral surface of the valve 50, and a ring member 61 press-fitted into the large-diameter side of the pressure release passage L4, and holds the valve 50 between the ring member 61 and the stepped portion. Then, the compressive stress is unlikely to be applied to the valve 50, and the deformation of the valve 50 is reduced to prevent the reduction in the control accuracy of the back pressure.