Nested Roller Screw Reducer for High Reduction Capacity
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Solution Overview
Problem
Conventional roller screw reducers have insufficient reduction capacity, making it difficult to couple them with high-speed electric motors, which are costly, and require frequent maintenance due to wear and energy inefficiency.
Innovation Solution
A double reduction stage reducer with oriented threads in the same direction for rollers and housing, allowing for improved reduction capacity up to 1/180 without size increase, enabling the use of high-speed, low-cost electric motors and reducing energy consumption and wear through efficient braking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional roller screw reducers are used, then the structure is simple, but the reduction capacity is insufficient for high-speed electric motors
Solution Approach 1:
The reducer is divided into two independent stages: a first roller screw stage and a second roller screw stage. Each stage has its own screw, rollers, and housing, allowing the reduction ratio to be compounded (e.g., 1/9 × 1/9 = 1/81 or 1/9 × 1/20 = 1/180). This segmentation enables high reduction capacity while maintaining relatively simple individual stage structures.
Solution Approach 2:
The second roller screw stage is nested within the housing of the first stage. The outer housing of the first stage serves as the inner housing for the second stage, creating a compact nested configuration. This allows two reduction stages to be combined in a space-efficient manner without significantly increasing overall device complexity.
2Ease of manufacture
If the reduction capacity is increased to match high-speed electric motors, then the reducer can be coupled with inexpensive motors, but the reducer size would increase
Solution Approach 1:
The second roller screw stage is nested within the housing of the first stage. The outer housing of the first stage serves as the inner housing for the second stage, creating a compact nested configuration. This allows two reduction stages to be combined in a space-efficient manner without significantly increasing overall device complexity.
Solution Approach 2:
The patent utilizes the radial dimension by arranging rollers perpendicular to the screw axis, and the axial dimension through the nested staging. This multi-dimensional arrangement allows high reduction ratios to be achieved within a compact volume, avoiding a simple linear increase in size.
3Volume of stationary object
If conventional single-stage roller screw reducers are used, then the device is compact, but the reduction ratio is insufficient (maximum 1/9 or 1/20)
Solution Approach 1:
The reducer is divided into two independent stages: a first roller screw stage and a second roller screw stage. Each stage has its own screw, rollers, and housing, allowing the reduction ratio to be compounded (e.g., 1/9 × 1/9 = 1/81 or 1/9 × 1/20 = 1/180). This segmentation enables high reduction capacity while maintaining relatively simple individual stage structures.
Solution Approach 2:
The second roller screw stage is nested within the housing of the first stage. The outer housing of the first stage serves as the inner housing for the second stage, creating a compact nested configuration. This allows two reduction stages to be combined in a space-efficient manner without significantly increasing overall device complexity.
4Device complexity
If roller threads are oriented in the same direction as screw threads (conventional design), then the mechanism is simple, but the reduction capacity is limited
Solution Approach 1:
The patent applies different thread orientation configurations to different stages of the reducer. The first stage can use conventional same-direction threading, while the second stage uses opposite-direction threading between the outer housing and rollers. This local differentiation optimizes reduction capacity in each stage without unnecessarily complicating the overall design.
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 improved reduction capacity allows for precise braking with low energy consumption, reduced maintenance needs, and integration of advanced features like collision avoidance systems, while compensating for brake pad and disc wear.
Implementation Method 1
roller screw, threaded rollers... the rollers have threads arranged perpendicular to the screw axis... the roller rotation drives the housing in translation when the screw is fixed
Implementation Method 2
reduction capacity that is insufficient for coupling with a very high-speed electric motor... reduction capacity up to 1/180
Data Source
Figure 1~2
Figure 3
AI summary
The reducer (10; 23; 34) comprises: - a screw (12), - threaded internal rollers (14), - a tapped internal casing (18). The internal rollers (14) each being in mesh firstly with the screw (12) and secondly with the internal casing (18) by means of at least one thread (14A) of opposite hand to a thread (12A) of the screw (12) and of the same hand as a thread (18A) of the internal casing. The reducer (10; 23; 34) further comprises: - a tapped external casing (30), - external rollers (28) each in mesh firstly with the internal casing (18) and secondly with the external casing (30). The external rollers (28) are provided with at least one thread (28A) of opposite hand to a thread (18A) of the internal casing (18) and of the same hand as a thread (30A) of the external casing (30).