Variable Cross-Section Steering Gearbox Casing Design
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Solution Overview
Problem
The existing manufacturing methods for steering casings are costly and lack rigidity, particularly in achieving the required mechanical strength and precise geometry for guiding and movement limitation, with issues such as noisy metal-to-metal contacts and difficulty in achieving constant internal diameters and adequate rigidity in reinforced plastic materials.
Innovation Solution
A steering casing design comprising at least two joined parts, forming an ovoid or tapered shape with a larger central section and smaller ends, incorporating internal reinforcing ribs and using materials like reinforced plastics or aluminum alloys, with joining techniques like rotary friction welding or gluing to enhance rigidity and simplify manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a steering casing is produced by casting in aluminum alloy, then the casing can be obtained with good mechanical strength, but the manufacturing cost increases due to numerous manufacturing steps and the need for long cores with reliefs
Solution Approach 1:
The steering casing is divided into two separate half-casings that can be manufactured independently using simpler molding processes without requiring long internal cores. This segmentation eliminates the need for complex core movements and reliefs, reducing manufacturing cost while maintaining structural integrity through subsequent joining of the halves
Solution Approach 2:
The invention changes the manufacturing approach from traditional single-piece casting to a modular assembly of two half-casings. This parameter change in the manufacturing process allows for simpler, more cost-effective production while achieving the same mechanical strength requirements through proper joining techniques
2Shape
If two long cores are used during molding to obtain the internal tubular shape, then the casing can be formed, but the internal section becomes non-constant with smaller mid-length and larger ends
Solution Approach 1:
By dividing the casing into two half-casings manufactured separately, the invention avoids the use of long internal cores that cause diameter variation. Each half-casing can be molded with simpler geometry, and when assembled, they form a casing with constant internal diameter throughout its length
3Reliability
If internal rings are added to contain radial movement of the rack, then correct guiding is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The guiding function previously requiring separate internal rings is merged into the half-casing structure itself. The half-casings are designed with integrated features that provide both structural support and rack guiding, eliminating the need for additional internal rings and reducing overall device complexity
4Reliability
If massive rings or limiters working in shear are used to achieve motion limitation, then the functions are achieved, but the mechanical performance is penalized
Solution Approach 1:
The invention changes the design parameter of the limiting structures from massive rings to thin-walled half-casings with optimized geometry. This parameter change allows motion limitation to be achieved through the structural design of the half-casings themselves, maintaining mechanical performance while reducing material usage
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 design simplifies manufacturing, reduces costs, and provides enhanced rigidity and precise geometry, allowing for effective stiffening and integration of guiding components, while minimizing noise and mechanical penalties, and enabling the use of reinforced plastics for improved structural performance.
Implementation Method 1
said two half-casings being joined together, in particular by rotary friction welding
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
The gear box (1) has an elongated shape, where the gear box is hollow for accommodating and guiding a rack (2). A pinion engages the rack and optionally engages a pusher pressing the pinion against the rack. A right crank-case (10) and a left crank-case (11) are combined so as to impart an ovoid shape or spindle shape to the gear box with a section that is significantly greater in a central region than in region of ends (6, 7) of the gear box.