Turbine Rotor Threaded Shaft Impeller Connection
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Solution Overview
Problem
Existing methods for connecting shafts and impellers in turbines or compressors, such as friction or beam welding, often result in hot cracks, especially when using weight-optimized materials like gamma-TiAl alloys or ceramics, which are difficult to weld and lead to structural weaknesses.
Innovation Solution
A mechanical connection with a threaded design, combined with a soldered, welded, adhesive, crystallization, or clamping bond, where the main load is absorbed by the mechanical thread connection, reducing the need for strong welds and allowing the use of challenging materials, and optionally incorporating an adhesive or clamping mechanism for additional stability and corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If friction welding or beam welding is used to connect shaft and impeller, then a strong connection is achieved, but hot cracks occur in highly loaded zones especially when using weight-optimized materials
Solution Approach 1:
The connection is divided into two independent parts: a mechanical screw connection (threads) and a thermal connection (soldering/welding/adhesive). The mechanical threads absorb the main loads while the thermal connection provides locking and sealing, preventing hot cracks by reducing stress on the welded/soldered joints
Solution Approach 2:
The threaded mechanical connection acts as an intermediary that absorbs the majority of mechanical loads, thereby protecting the soldered/welded connection from excessive stress and preventing hot crack formation in the thermal connection zone
2Weight of moving object
If weight-optimized materials like gamma-TiAl alloys or ceramics are used for the impeller, then reduced weight and lower moment of inertia are achieved, but these materials are difficult to beam-weld or friction-weld
Solution Approach 1:
The connection method is segmented into mechanical threading (easy to implement with difficult-to-weld materials) and thermal bonding (used only for locking and sealing, not for load bearing), making the overall assembly feasible with weight-optimized materials like gamma-TiAl alloys and ceramics
Solution Approach 2:
The primary load-bearing function is transferred from thermal connection (welding) to mechanical connection (screws/threads), replacing the mechanical welding system with a threaded fastening system that is much easier to implement with difficult-to-weld materials
3Strength
If a strong soldered or welded connection is used to ensure structural integrity, then connection strength is improved, but hot cracks occur and materials like gamma-TiAl alloys become difficult to process
Solution Approach 1:
The connection function is segmented into load-bearing (mechanical threads) and locking/sealing (thermal connection). This allows the thermal connection to be much smaller and weaker without compromising overall strength, thereby eliminating hot cracks while maintaining structural integrity
Solution Approach 2:
The threaded mechanical connection serves as an intermediary that carries the main loads, allowing the soldered/welded connection to be minimal and not subjected to high stresses that would cause hot cracks
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 provides a sturdy, weight-reduced connection that minimizes hot cracks, allows for the use of difficult-to-weld materials, improves response behavior in supercharging devices, and offers corrosion protection and vibration damping, while maintaining structural integrity and reducing imbalance.
Implementation Method 1
the shaft and the at least one impeller are screwed to one another and the shaft and the impeller are fixed with respect to one another by a soldered connection and/or a welded connection and/or by an adhesive bond
Implementation Method 2
the shaft and the at least one impeller are screwed to one another and the shaft and the impeller are fixed with respect to one another by a soldered connection and/or a welded connection
Implementation Method 3
the shaft and the at least one impeller are screwed to one another and the shaft and the impeller are fixed with respect to one another by a soldered connection and/or a welded connection
Implementation Method 4
the shaft and the at least one impeller are screwed to one another and the shaft and the impeller are fixed with respect to one another by a soldered connection and/or a welded connection and/or by an adhesive bond and/or by a crystallization connection
Data Source
AI summary
A rotor for at least one of a turbine and a compressor of a supercharging device may include a shaft defining an axis of rotation and at least one impeller. The at least one impeller may have a thread which is arranged coaxially to the axis of rotation. The shaft may include a complementary thread which is arranged coaxially to the axis of rotation. The shaft and the at least one impeller may be secured together via the respective threads. The shaft and the at least one impeller may be fixed with respect to one another via at least one of a soldered connection, a welded connection, an adhesive bond, a clamped connection and a crystallization connection.