Linear Actuator Layout for Low-Play Steering Column Adjustment
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Solution Overview
Problem
Conventional actuators used in vehicle components, such as seat and steering column adjustment, face challenges in reducing size and axial play, simplifying design, and increasing durability due to load transmission through plastic gear housings, which can lead to failures and reduced mechanical resistance.
Innovation Solution
The actuator design positions the first connection interface between the second connection interface and the transmission element, allowing load transmission primarily through the spindle and lock nut, eliminating reliance on the plastic gear housing, and incorporates thrust bearings within housings to protect them from contaminants, enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If loads are transmitted through the plastic gear housing, then the actuator can be compact, but the durability and mechanical resistance are reduced due to potential housing failures
Solution Approach 1:
The load transmission function is extracted from the plastic gear housing and transferred to the metal spindle and lock nut assembly. The connection interfaces are designed to engage directly with the external thread on the metal spindle, creating a separate load path that does not rely on the gear housing for structural support.
Solution Approach 2:
The actuator employs a composite material strategy by using metal (spindle and lock nut) for high-strength load-bearing components and plastic (gear housing) for enclosure and gear mounting functions only. This material differentiation allows the metal components to handle tensile and compression loads while the plastic housing provides compact enclosure.
2Ease of manufacture
If the actuator design is simplified to reduce manufacturing costs, then production becomes more efficient, but axial play and mechanical resistance may increase
Solution Approach 1:
The lock nut is pre-threaded onto the spindle with precise thread engagement, and the connection interfaces are pre-configured with matching internal and external threads. This preliminary precision threading ensures minimal axial play is built into the assembly before final installation, maintaining manufacturing precision while using cost-effective standard threading practices.
3Device complexity
If thrust bearings are exposed to the environment, then the actuator structure is simpler, but contaminants can reduce bearing performance and durability
Solution Approach 1:
The thrust bearings are nested within the gear housing and connection interface housings, which act as protective enclosures. The gear housing surrounds the drive shaft and transmission element, while the connection interface housings surround the respective thrust bearings, creating nested protective layers that shield the bearings from contaminants while maintaining a relatively compact overall structure.
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
This configuration improves actuator durability by distributing loads effectively through the spindle and transmission elements, increasing tensile and compression resistance, and protecting thrust bearings from contamination, thereby enhancing mechanical resistance and reliability.
Implementation Method 1
a lock nut disposed in the first interface housing, the lock nut having an internal thread that is engaged with, and fixed to, the external thread
Implementation Method 2
a first thrust bearing mounted on the spindle, the thrust bearing disposed in the first interface housing between the lock nut and the first end
Implementation Method 3
an elastic element disposed between the lock nut and the thrust bearing
Implementation Method 4
a gear unit that transmits the output of the drive motor to the spindle. The gear unit includes a gear housing that surrounds a portion of the drive shaft, a drive gear disposed in the gear housing that engages the gear teeth of the transmission element
Implementation Method 5
The transmission element is part of a worm drive mechanism and has radially extending gear teeth that are configured to engage a drive gear of a DC drive motor
Data Source
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AI summary
An actuator is suitable for providing linear motion between two points, and may be used, for example, in motorized positioning of an automobile steering column. The actuator includes a threaded spindle connected to a drive motor via a gear set, a first connection interface mounted on the spindle and engaged with the spindle thread, and a second connection interface mounted on the spindle and engaged with the spindle thread. The second connection interface is moveable along the spindle axis relative to the first connection interface when the spindle is driven by the drive motor. The actuator is arranged such that the first and second connection interfaces are disposed on the same side of the gear set.