Modular Blade Bolt Joint With Wedge Preload Mechanism
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Solution Overview
Problem
Current modular blade joint systems for wind turbines require complex and inefficient methods to achieve and maintain pre-stressing of bolts due to limited space, leading to potential loss of preload and increased maintenance needs.
Innovation Solution
A mechanical joining device using metal lateral caps, upper and lower wedges, and transverse bolts that apply force to pre-stress bolts through a simple mechanical action, leveraging the force-multiplying effect of the wedge to achieve precise preload distribution without fatigue in the transverse bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spacer-based pre-stressing methods are used, then pre-stressing can be maintained, but the device complexity increases and space requirements are not optimized
Solution Approach 1:
The invention extracts the pre-stressing function from complex spacer systems and concentrates it into a single wedge element. The wedge is inserted into a hollow area of the insert, and when forced, it directly generates the pre-stressing force on the bolt through mechanical action, eliminating the need for multiple spacers and their associated complexity.
Solution Approach 2:
The invention changes the physical state and positioning parameters by inserting the wedge into the hollow area of the insert. The wedge's position and orientation are specifically designed to convert the applied force into pre-stressing force on the bolt, optimizing the mechanical action within the limited space available.
2Reliability
If multiple spacers are placed at intervals to maintain pre-stressing, then preload stability is achieved, but the ease of operation decreases
Solution Approach 1:
The invention merges the functions of multiple spacers into a single wedge element. The wedge combines the pre-stressing generation and maintenance functions in one component that is inserted into the hollow area of the insert, simplifying the operation to a single insertion and forcing action rather than multiple spacer installations.
Solution Approach 2:
The wedge system is designed to be self-servicing within the hollow area of the insert. Once the wedge is inserted and forced, it automatically generates and maintains the pre-stressing force through its mechanical action on the bolt, without requiring additional operational steps or external maintenance during service.
3Force
If force is applied directly to stretch the bolt initially, then pre-stressing is achieved, but the force application becomes complex due to limited space
Solution Approach 1:
The wedge acts as an intermediary mechanical element between the applied force and the bolt. Instead of applying force directly to the bolt in the limited space, the wedge is inserted into the hollow area and converts the applied force into the necessary pre-stressing force on the bolt through its inclined plane action, simplifying the force application process.
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
The solution allows for efficient and precise pre-stressing with reduced application force, minimizing the likelihood of preload loss and eliminating the need for maintenance, as the system maintains preload stability and distribution effectively.
Implementation Method 1
pre-stress each of the inserts with a device based on the great strength generated by a wedge positioned perpendicularly to the direction of movement
Implementation Method 2
The angle of the wedge determines the ratio between the applied forces and the resulting transverse forces, due to the decomposition of forces in the inclined plane
Implementation Method 3
friction on the inclined planes of the wedges prevents displacement
Data Source
Figure 1~2
Figure 3~4b
Figure 5
AI summary
The invention relates to a device for joining a modular blade, the joint being formed by a plurality of bolts (8) that are secured between inserts (3 and 4) housed in the composite material of two modules (1 and 2) to be jointed. The device allows the bolt (8) to be preloaded with less application force and greater precision than known systems, also ensuring that the device is maintenance free. For the purpose, each device is formed by lateral caps (9), an upper wedge (10) and a lower wedge (11), and transverse screws (12), all of this surrounding the corresponding bolt (8) disposed inside of a hole between two blade modules (1 and 2). When a force F1 is applied to the wedges (10 and 11), the caps (9) respond with a force that separates the modules (1 and 2) and pre-stress the bolt (8).