Planetary Roller Screw Cage Reset for Axial Offset Control
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Solution Overview
Problem
In high-pressure applications, such as large-diameter pipes, screw-driven forced seal ball valves face challenges due to high frictional forces and axial offsets in planetary roller screw devices, leading to increased operation torque and reduced working life, as well as failures caused by poor manufacturing precision and environmental factors affecting the positional relationship between male and female threads.
Innovation Solution
A cage reset planetary roller screw device is introduced, featuring a cage with protruding ends and limit blocks that maintain the planetary rollers in the correct position between the male and female threads, allowing for accurate resetting during non-load rotation strokes, ensuring proper working conditions and reducing frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If planetary roller screw device is used to reduce frictional force, then operation torque is reduced, but axial offset accumulates due to poor manufacturing precision and working environment
Solution Approach 1:
The cage is provided with protruding ends that preliminarily establish the correct positional relationship between planetary rollers and thread members before operation begins. The limit blocks are pre-positioned on the male or female thread members to define the initial alignment, preventing axial offset accumulation from the start of operation.
Solution Approach 2:
The protruding ends of the cage contact the limit blocks during non-load rotation strokes to provide feedback on positional deviation. This contact mechanism detects and corrects axial offsets by pushing the cage back to the correct position, ensuring continuous maintenance of proper alignment between planetary rollers and thread members.
2Ease of operation
If planetary rollers are allowed to move freely between threads, then ease of operation is improved, but axial offset causes cage contact with thread members leading to failure
Solution Approach 1:
The cage acts as an intermediary component between the planetary rollers and thread members. The protruding ends of the cage mediate the interaction by contacting limit blocks to correct positional deviations, allowing rollers to move freely during operation while preventing harmful axial offsets that would cause cage contact with thread members.
3Reliability
If manufacturing precision is improved to maintain positional relationship, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
Instead of requiring high manufacturing precision parameters, the invention changes the approach by introducing adjustable mechanical elements (protruding ends and limit blocks). These elements compensate for manufacturing tolerances and environmental factors through mechanical adjustment during operation, rather than relying on tight manufacturing specifications.
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 effectively maintains the planetary rollers in the correct initial working position, reducing operational torque and extending the working life of the device by ensuring precise alignment and minimizing axial offsets, thus maintaining the integrity of the mechanical seal.
Implementation Method 1
a number of planetary rollers which are disposed between the male and female threads and provided with ring grooves, a distance between adjacent ring grooves corresponding to the pitch; and wherein the ring grooves of the planetary rollers respectively mesh with the male thread and the female thread
Implementation Method 2
the male thread member and/or the female thread member are provided with the limit blocks which are in contact with the protruding ends of the cage in the circumferential direction of the cage
Data Source
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AI summary
The present disclosure relates to a cage reset planetary roller screw device comprising a male thread member provided with a male thread and a female thread member provided with a female thread, a number of planetary rollers disposed between the male thread and the female thread. The planetary rollers are disposed between the male thread and the female thread through a cage, and the planetary rollers are disposed in roller retaining pockets of the cage. The side surfaces of the cage are provided with convex ends. The male thread member and/or the female thread member are provided with limit blocks that are in contact with the convex ends of the cage in the circumferential direction of the cage.