Jet Pump Bolt Locking Device Using Elastic Serrated Teeth
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Solution Overview
Problem
Conventional bolt fixing devices for jet pump beams require precise machining of external teeth and internal tooth-like grooves to ensure accurate meshing, making it difficult to easily and reliably lock the head bolt against rotation during installation of the inlet mixer in a boiling water reactor.
Innovation Solution
A bolt fixing device with a lock cap and body housing that uses serrated upper and lower surface teeth, where the lock cap is axially movable and rotatable, and a spring member applies elastic force to mesh the teeth easily, allowing for reliable rotational locking and unlocking of the head bolt without precise machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bolt fixing devices with external teeth and internal tooth-like grooves are used, then the head bolt can be locked against rotation, but precise machining is required for accurate meshing which increases manufacturing complexity and time
Solution Approach 1:
The invention inverts the conventional tooth meshing concept by replacing the internal tooth-like grooves with a smooth cylindrical inner peripheral surface. The locking function is achieved not by interlocking teeth but by the lock cap's outer peripheral surface engaging with the head bolt's polygonal head, while the smooth inner surface allows easy axial movement. This inversion eliminates the need for precise machining of complementary tooth profiles.
Solution Approach 2:
The invention extracts the tooth-like grooves from the lock cap structure, removing the complex internal toothed geometry that required precise machining. The locking function is achieved through the outer peripheral teeth engaging with the head bolt, while the inner peripheral surface remains smooth, separating the locking function from the movement function and simplifying manufacturing.
2Reliability
If external teeth and internal tooth-like grooves are designed for accurate meshing, then rotational locking is achieved, but the complexity of the device increases due to precise dimensional requirements
Solution Approach 1:
The invention simplifies the device structure by inverting the meshing concept: instead of having both external and internal teeth that must mesh precisely, the lock cap has only external teeth for locking, while the inner peripheral surface is smooth. This reduces the number of complex geometric features and eliminates the need for precise dimensional coordination between mating tooth profiles.
Solution Approach 2:
The invention removes the internal tooth-like grooves from the lock cap design, extracting the complexity of dual-tooth systems. The locking function is achieved solely by the external teeth engaging with the head bolt's polygonal head, while the smooth inner surface provides a simple guide for axial movement, significantly reducing geometric complexity.
3Ease of operation
If the lock cap is designed to slide axially for meshing, then locking and unlocking is possible, but the operation becomes difficult without accurate dimensional setting
Solution Approach 1:
The invention inverts the operational mechanism by making the inner peripheral surface smooth instead of toothed. This allows the lock cap to slide axially freely along the head bolt without requiring precise dimensional clearance or interference fits. The locking action is achieved through the external teeth engaging with the polygonal head, while the smooth inner surface provides unrestricted axial movement, greatly easing operation.
4Reliability
If precise machining is performed on external teeth and internal grooves, then accurate meshing is achieved, but manufacturing time and cost increase
Solution Approach 1:
The invention removes the internal tooth-like grooves from the lock cap, extracting the manufacturing complexity associated with machining spiral or helical tooth profiles. The lock cap can now be manufactured with a simple smooth inner cylindrical surface, which can be produced through standard turning or boring operations, significantly reducing manufacturing time and cost while maintaining reliable locking through the external teeth.
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 bolt fixing device allows for easy and reliable locking and unlocking of the head bolt, reducing wear and improving reliability by eliminating the need for precise machining, enabling efficient installation and removal of the inlet mixer in a boiling water reactor.
Implementation Method 1
a spring member that applies elastic force to the lock cap toward the integral rotation side above
Data Source
AI summary
A bolt fixing device (35) for a jet pump beam comprises: a lock cap (36) which is fitted to the polygonal head portion (32) of a head bolt (30), can move in the vertical axis direction, and can rotate together with the head bolt (30); a body housing (37) which houses the lock cap (36) and which is installed on the upper surface of a jet pump beam (27); and an elastic member (40) which is provided within the body housing (37) at a position below the lock cap (36) and which applies an elastic force to the lock cap (36) in the vertically upward direction. The bolt fixing device (35) is configured so that the lock cap (36) is pushed up by the elastic force of the elastic member (40) and engages upper surface teeth with lower surface teeth, the upper surface teeth being formed on the upper surface of the flange of the lock cap (36), the lower surface teeth being formed on the lower surface of the engagement flange of the body housing (37). Thus, the head bolt (30) of the jet pump beam (27) is fixed. As a result of this configuration, when installing an inlet mixer, the head bolt of the jet pump beam is simply and reliably locked against rotation.