Electric Power Steering Gear System with Ball Nut Assembly
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Solution Overview
Problem
Existing vehicle steering apparatuses for heavy trucks lack efficient and responsive power steering systems, particularly in commercial vehicles, which can lead to increased effort and fatigue during steering maneuvers, especially in tight turns or heavy loads.
Innovation Solution
An electric power steering gear system that includes a steering member with an externally threaded portion connected to a ball nut assembly, which is rotated by a motor, and utilizes a gear system to amplify torque, assisted by sensors and an electronic control unit to optimize steering based on vehicle conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a motor is connected with the ball nut assembly to apply rotational force, then steering effort is reduced and responsiveness is improved, but device complexity increases
Solution Approach 1:
The patent combines the electric motor, ball nut assembly, and gear members into an integrated power steering system. The motor is directly connected to the ball nut assembly, and the gear members are incorporated within the same housing, creating a unified mechanism that reduces steering effort while managing complexity through functional integration rather than separate components
Solution Approach 2:
The patent replaces traditional mechanical steering systems with an electrically-assisted system. The electric motor substitutes for purely mechanical force transmission, providing powered assistance to the steering mechanism. This substitution reduces the manual effort required while the mechanical gear members provide the necessary force multiplication
2Power
If gear members are used to amplify torque, then steering responsiveness is improved, but device complexity increases
Solution Approach 1:
The patent employs a nested gear arrangement where first and second gear members are positioned within the housing and engage with each other in a compact configuration. The gear members are nested within the overall power steering assembly, allowing torque amplification through multiple gear stages without requiring a large spatial footprint, thus managing complexity through efficient spatial arrangement
Solution Approach 2:
The gear members serve as intermediary elements between the electric motor and the steering member. The first gear member receives rotational force from the motor, and the second gear member transmits this force to the steering member with amplified torque. These intermediary gears enable efficient power transmission and torque multiplication while maintaining a manageable system architecture
3Ease of operation
If the ball nut assembly is rotated relative to the steering member, then axial movement is achieved for wheel turning, but manufacturing precision requirements increase
Solution Approach 1:
The ball nut assembly utilizes the externally threaded portion of the steering member in a self-mating configuration. The threaded portion and ball nut assembly are designed to work together as an integrated mechanism, where the rotation of the ball nut assembly directly converts to axial movement of the steering member through the threaded engagement. This self-service mechanism reduces the need for additional precision components while maintaining steering maneuverability
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 system reduces steering effort and improves responsiveness by applying precise axial forces to the steering member, enhancing maneuverability and reducing driver fatigue, especially in heavy trucks under various load conditions.
Implementation Method 1
The ball nut assembly is connected with the externally threaded portion of the steering member. The ball nut assembly is rotatable relative to the steering member to axially move the steering member.
Implementation Method 2
A first gear member is rotatable in response to rotation of a steering wheel. A second gear member disposed in meshing engagement with the first gear member rotates in response to rotation of the first gear member. The ball nut assembly rotates relative to the steering member in response to rotation of the second gear member.
Implementation Method 3
An electrical motor connected with the ball nut assembly is operable to apply a rotational force to the ball nut assembly to urge the ball nut assembly to rotate relative the steering member.
Data Source
AI summary
An apparatus for use in turning steerable vehicle wheels includes a steering member connected to at least one steerable vehicle wheel. The steering member moves axially to effect turning movement of the at least one steerable vehicle wheel. The steering member has an externally threaded portion. A ball nut assembly is connected with the externally threaded portion of the steering member. The ball nut assembly is rotatable relative to the steering member to axially move the steering member. A first gear member is rotatable in response to rotation of a steering wheel. A second gear member disposed in meshing engagement with the first gear member rotates in response to rotation of the first gear member. The ball nut assembly rotates relative to the steering member in response to rotation of the second gear member.