Tapered Lubricant Holder for Refrigerant Compressor Low-Speed Delivery
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Solution Overview
Problem
Refrigerant compressors with variable speeds face challenges in reliable lubrication at low speeds due to the dependence of lubricant rise height on rotational speed, leading to inefficient lubricant delivery and potential damage from fluctuations in delivery rate.
Innovation Solution
A lubricant receptacle design featuring a sleeve element with a tapered clear cross-section and an inner element with a spirally grooved surface, allowing relative rotation to create a gap for lubricant conveyance, ensuring sufficient centrifugal force at low speeds and smooth pressure transition, with adjustable gap width for optimal flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clear inner radius of the crankshaft is increased to improve lubricant delivery at low speeds, then centrifugal force is enhanced, but the structural transition becomes abrupt causing high pressure drop and reduced lubricant flow
Solution Approach 1:
The crankshaft is designed with a tapered clear cross-section where the clear inner radius varies along the longitudinal axis. The lower section has a larger clear inner radius to generate sufficient centrifugal force at low rotational speeds, while the upper section transitions to a smaller radius to reduce pressure drop. This local variation in geometric properties resolves the contradiction between needing large radius for centrifugal force and small radius for pressure drop reduction.
2Productivity
If the rotational speed of the crankshaft is increased to improve lubricant conveyance, then centrifugal force increases, but this is not feasible for variable-speed compressors operating at low speeds
Solution Approach 1:
Instead of changing the rotational speed parameter to improve lubricant conveyance, the invention changes the geometric parameter of the crankshaft by implementing a tapered clear cross-section. This allows the system to maintain effective lubricant delivery across a wide range of rotational speeds, particularly at low speeds where variable-speed compressors operate, without requiring high rotational velocity.
3Device complexity
If a fixed gap between the inner element and crankshaft wall is used, then the structure is simple, but the delivery rate fluctuates due to thermal expansion and viscosity changes
Solution Approach 1:
The lubricant receptacle incorporates an adjustable gap mechanism between the inner element and the crankshaft wall. This allows the gap width to be dynamically adjusted based on operating conditions such as temperature and viscosity changes, maintaining stable delivery rate. The adjustment capability compensates for thermal expansion and fluid property variations without requiring complex control 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
Ensures reliable lubrication at low speeds by maintaining sufficient centrifugal force and continuous flow, reducing the risk of insufficient delivery and damage, while accommodating varying operating parameters.
Implementation Method 1
the maximum height to which the lubricant in the lubrication chamber can be raised in this way is reached in the region of the clear inner diameter of the crankshaft or bore and depends on the square of the rotational speed of the lubrication chamber as well as the square of the clear inner radius of the crankshaft or lubrication chamber
Implementation Method 2
the inner element and the sleeve element are rotatable relative to each other about the longitudinal axis of the sleeve element and/or the longitudinal axis of the inner element, wherein the clear cross-section tapers from the lower end to the upper end of the sleeve element
Data Source
Figure 1~2
Figure 3
AI summary
Lubricant intake (1) for vertical conveyance of lubricant (15) by means of a crankshaft (2) of a refrigerant compressor (3), comprising a sleeve element (4) with a clear cross-section (5) extending along a longitudinal axis (6) from an upper end (7) to a lower end (8), an inner element (9) having a lateral surface (10) extending along a longitudinal axis (11) of the inner element (9) from a lower end (12) to an upper end (13), wherein in an operating condition the inner element (9) with its lateral surface (10) is arranged at least sectionally within the clear cross-section (5). According to the invention, the clear cross-section (5) tapers from the lower end (8) to the upper end (7) at least in a receiving segment (33) provided for receiving the inner element (9), and the inner element (9) tapers in the area of the lateral surface (10) from the lower end (12) to the upper end (13).