Eccentric Roller Transmission Layout for Balanced High-Torque Drives
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Solution Overview
Problem
Conventional transmissions face challenges in achieving high transmission ratios, high torque, and torsional rigidity in a compact and stable manner, with issues related to dynamic imbalance and metal-to-metal contact leading to noise and wear.
Innovation Solution
A transmission design featuring a drive shaft with multiple eccentric regions of varying widths, offset in the circumferential direction, and rollers accommodated in recesses of a cage with radial freedom, where the cage is rotationally fixed to the output shaft, and rollers are axially delimited by a softer spacer ring, minimizing dynamic imbalance and avoiding metal-to-metal contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional transmissions use standard gear mechanisms to achieve high transmission ratios, then the transmission ratio is improved, but the device complexity and size increase
Solution Approach 1:
The drive shaft is segmented into multiple eccentric regions with different widths, each creating a specific cam profile. This segmentation allows the transmission to achieve high reduction ratios through the combined effect of multiple simpler eccentric regions rather than requiring a single complex gear system.
Solution Approach 2:
The invention transitions from traditional planar gear mechanisms to a three-dimensional cam mechanism where the eccentric regions create radial and axial motion components. This dimensional change enables compact high-ratio transmission within a smaller volume by utilizing spatial motion paths.
2Force
If conventional transmissions use metal-to-metal contact for torque transmission, then the torque capacity is improved, but noise and wear increase
Solution Approach 1:
A spacer ring is introduced as an intermediary element between the rollers and the cage. This spacer ring prevents direct metal-to-metal contact between the rollers and cage, reducing noise and wear while maintaining effective torque transmission through the roller-cage interface.
Solution Approach 2:
The invention changes the contact parameters by using rollers that roll on the cam profiles created by eccentric regions, transforming sliding friction into rolling friction. This parameter change significantly reduces wear and noise while maintaining high torque transmission capacity.
3Power
If the drive shaft has multiple eccentric regions with varying widths, then the transmission ratio and torque are improved, but dynamic imbalance increases
Solution Approach 1:
The spacer ring acts as a counterbalancing element that compensates for the dynamic imbalance created by the multiple eccentric regions with varying widths. By strategically positioning and dimensioning the spacer ring, the invention offsets the unbalanced forces and moments, maintaining rotational stability while achieving high transmission ratios.
4Strength
If the cage is made as one piece with the output shaft, then torsional rigidity is improved, but manufacturing complexity increases
Solution Approach 1:
The cage is merged with the output shaft to form a single integral component. This merging eliminates the need for separate cage and output shaft parts, ensuring rigid torque transmission from the rollers to the output shaft while actually simplifying manufacturing by reducing the number of parts and assembly steps.
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 design enables high torque and transmission ratio in a compact space with reduced noise and improved stability, ensuring smooth operation and reduced radial forces, while maintaining torsional rigidity and minimizing dynamic imbalance.
Implementation Method 1
a drive shaft, e.g., a hollow shaft, of the transmission has multiple eccentric regions with differing widths in the axial direction, the high points of which are offset relative to one another in the circumferential direction
Implementation Method 2
During operation, e.g., when the drive shaft rotates, the respective rollers are made to roll and/or slide on the respective cam disk region by the respective eccentric region
Data Source
AI summary
A drive includes a transmission driven by an electric motor. A drive shaft of the transmission has multiple eccentric regions with differing widths in the axial direction, in which the high points thereof are offset relative to one another in the circumferential direction. The respective eccentric region is radially surrounded by a respective cam disk region, e.g., of a housing part of the transmission. Respective rollers are accommodated in respective recesses of a cage and arranged with a radial degree of freedom. The cage is rotationally fixed to the output shaft of the transmission, and the output shaft along with the cage is rotatably mounted both relative to the cam disk regions and relative to the drive shaft. During operation, the respective rollers are made to roll and/or slide on the respective cam disk region by the respective eccentric region. The eccentric regions are arranged behind one another in the axial direction such that the dynamic imbalance is minimized and/or eliminated.