Power Steering Preload Adjustment via Plug and Spring
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Solution Overview
Problem
Existing power steering apparatuses face challenges in maintaining a consistent preload between the worm and worm wheel due to manufacturing and assembly errors, leading to variations in biasing force and preload, which affects the center distance and engagement between the worm and worm wheel over time.
Innovation Solution
A power steering apparatus with a plug having a male screw that is screwed into a housing, an elastic member providing preload between the worm and worm wheel, and a plug fixing member that is adjusted to a predetermined position to maintain the desired preload, using a lock nut or caulking for fixation, allowing for easy adjustment and measurement of the preload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compression coil spring is used as a preload means, then the preload between the worm and worm wheel can be maintained, but manufacturing errors and assembly errors cause variation in the biasing force and preload
Solution Approach 1:
The patent applies preliminary action by pre-assembling the worm, worm wheel, and compression coil spring as a unit before final installation. The compression spring is pre-compressed to the correct preload value during assembly, ensuring that the preload is correctly established before the system enters service. This preliminary preparation eliminates the need for field adjustment and ensures consistent preload despite manufacturing tolerances.
Solution Approach 2:
The patent utilizes parameter changes by varying the free length of the compression coil spring to compensate for manufacturing and assembly errors. By adjusting the spring's free length parameter, the biasing force can be precisely controlled to achieve the desired preload value. This allows the system to maintain reliable preload performance despite variations in other dimensional parameters.
2Ease of manufacture
If the center distance between worm and worm wheel is set easily, then assembly is simplified, but backlash may occur when engagement changes over time
Solution Approach 1:
The patent applies preliminary action by pre-compressing the compression coil spring during assembly to establish the correct center distance and eliminate backlash. The spring is pre-loaded to the appropriate value before final installation, ensuring that the worm and worm wheel are properly positioned relative to each other. This preliminary preparation ensures both easy assembly and long-term reliability by preventing future backlash.
Solution Approach 2:
The patent applies beforehand cushioning by using the compression coil spring to continuously apply a biasing force that maintains proper engagement between the worm and worm wheel. The spring acts as a cushion that compensates for wear and dimensional changes over time, ensuring that backlash is prevented throughout the service life of the mechanism. The elastic force of the spring provides continuous correction for engagement changes.
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 enables the adjustment and maintenance of a desired preload between the worm and worm wheel, regardless of manufacturing and assembly errors, ensuring consistent performance and reducing backlash by using a simple and effective structure for preload adjustment.
Implementation Method 1
The center distance between the worm and the worm wheel is suitably maintained by an elastic force of the preload means to prevent a backlash
Implementation Method 2
The preload means is formed by a compression coil spring
Data Source
AI summary
A power steering apparatus includes: a worm driven by a motor for assistance; a worm wheel engaged with the worm and transmitting an assist force to a steering shaft; a housing which houses the worm and the worm wheel; a plug having a male screw on an outer peripheral surface of the plug, the male screw being screwed with a female screw formed at the housing; an elastic member, one end of which in a biasing direction of the elastic member is supported by the worm and other end of which in the biasing direction is supported by the plug, giving a preload between the worm and the worm wheel; and a plug fixing member for fixing the plug, a position of which is adjusted to a screwing position at which the preload is a predetermined value, so that the plug is unrotatable with respect to the housing.