Actuator Drive Unit Parallel Gear Torque Distribution
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Solution Overview
Problem
Existing drive units for actuators with small electric motors face challenges in achieving a transmission ratio greater than one across multiple gear stages, leading to increased load and deflection in higher gear stages, which requires complex and costly solutions such as thicker shafts and robust materials, increasing space and material compatibility issues.
Innovation Solution
A drive unit with a gear train that includes a last gear stage with either one or two gear wheels connected in parallel, allowing for variable configuration based on expected load, enabling flexible torque transmission without the need for robust materials or additional reinforcement, thus optimizing the gear train for torque transmission while minimizing costs and space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gear stages are designed with higher transmission ratios to achieve slow actuator movement, then the torque transmission capability is improved, but the load on individual gear wheels increases requiring thicker shafts and robust materials
Solution Approach 1:
The gear wheel is segmented into multiple identical gear wheel segments that are distributed around the shaft. Each segment transmits a portion of the total torque, thereby reducing the load on individual gear wheels. This allows the use of thinner shafts and less robust materials while maintaining the required torque transmission capability.
Solution Approach 2:
Multiple identical gear wheel segments are combined to work together in transmitting torque. The segments are arranged circumferentially and engage with the counterpart gear wheel simultaneously, merging their torque transmission capabilities to achieve the required total torque while keeping individual segment loads manageable.
2Reliability
If gear wheels are made more stable and bigger to withstand increasing load, then the torque transmission reliability is improved, but the installation space requirement increases
Solution Approach 1:
Instead of making a single large gear wheel, the gear transmission is segmented into multiple smaller identical gear wheel segments. These segments are distributed around the shaft and each has reduced size compared to a single large gear wheel, thereby reducing the overall installation space while maintaining reliability through redundant load paths.
Solution Approach 2:
The gear wheel segments are positioned at specific locations around the shaft to optimize space utilization. Each segment is sized appropriately for its local load requirements, and the distributed arrangement allows for compact packaging within the actuator housing.
3Strength
If different materials or metal bushings are used to reinforce gear wheels, then the torque capacity is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
All gear wheel segments are made from the same material with identical geometry and properties. This homogeneity simplifies manufacturing by allowing mass production of identical segments, reducing tooling requirements, and eliminating the need for different material processing techniques. The uniform design makes assembly and maintenance simpler as well.
4Strength
If the shaft is made thicker to withstand higher torque, then the structural strength is improved, but the installation space and weight increase
Solution Approach 1:
The torque transmission is segmented across multiple gear wheel segments, which reduces the torque load on the shaft. This allows the use of a thinner, lighter shaft that would not be sufficient if it had to transmit the full torque through a single gear wheel. The shaft weight is reduced while maintaining adequate strength for the distributed load.
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 torque transmission with reduced load on individual gear wheels, enabling cost savings and compact design by using uniform gear wheels, and accommodating varying torque requirements without the need for high-quality materials or additional reinforcement, making it suitable for applications with varying torque demands.
Implementation Method 1
a gear train having at least one first gear stage and a last gear stage which realizes a transmission ratio greater than one from the electric motor to an output wheel. Each gear stage is formed by a gear drive
Data Source
AI summary
A drive unit for an actuator having an electric motor, wherein the drive unit comprises a gear train having at least a first gear stage and a last gear stage, wherein the gear train realizes a transmission ratio of greater than one from the electric motor to an output wheel, wherein each gear stage is formed by a gear drive and wherein in the last gear stage, one gear wheel or alternatively two gear wheels connected in parallel are provided that each mesh with an upstream gear wheel of the gear train and with the output wheel, so as to transmit the torque acting on the last gear stage to this stage via the one gear wheel or alternatively distributed over the two gear wheels connected in parallel, wherein the drive unit is accommodated in a housing of the actuator that has at least a first and a second bearing support for the gear wheels of the last gear stage, and to form this last gear stage, the two bearing supports are fitted with the one gear wheel or alternatively with the two gear wheels connected in parallel.