Cross Shaft Universal Joint Thrust Piece Thermal Deformation
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Solution Overview
Problem
Existing cross shaft universal joints face challenges in suppressing rattling of yokes relative to the cross shaft while maintaining low manufacturing costs, as increasing the fitting margin to prevent rattling often results in higher rotational resistance.
Innovation Solution
A method of manufacturing a cross shaft universal joint involves heating and deforming thrust pieces made of synthetic resin to adjust their size, allowing for precise fitting without excessive precision, thereby reducing rattling and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fitting margin of thrust pieces is increased to suppress rattling of yokes relative to the cross shaft, then rattling is reduced, but rotational resistance increases
Solution Approach 1:
The patent applies parameter changes by heating the thrust pieces to alter their physical state and dimensions. The thermal expansion increases the outer diameter of the thrust pieces, enabling them to elastically deform and fit tightly into the bearing cups without excessive precision requirements. This resolves the contradiction by achieving reliable rattling suppression through thermal parameter modification rather than relying solely on mechanical fitting margins that would increase rotational resistance.
Solution Approach 2:
The patent directly utilizes thermal expansion by heating the thrust pieces before assembly. The heated thrust pieces expand in diameter, allowing them to be inserted into the bearing cups with elastic deformation. As they cool, they contract to create a tight interference fit that suppresses rattling effectively while maintaining low rotational resistance, thus resolving the technical contradiction between reliability and force.
2Reliability
If high precision in shape and assembly is used to suppress rattling, then rattling is reduced, but manufacturing cost increases
Solution Approach 1:
The patent changes the physical parameters of the thrust pieces through heating, allowing standard-precision components to achieve high-precision fitting results. The thermal expansion enables elastic deformation during assembly, and subsequent cooling creates a tight interference fit without requiring expensive high-precision manufacturing processes, thus resolving the contradiction between reliability and ease of manufacture.
Solution Approach 2:
The patent replaces the mechanical precision system with a thermal-mechanical system. Instead of relying on mechanically precise machining and assembly to suppress rattling, the invention uses thermal expansion and contraction to achieve the same effect. This substitution allows standard-precision components to achieve high-precision fitting results, significantly reducing manufacturing costs while maintaining reliable rattling suppression.
3Manufacturing precision
If the thrust piece size is adjusted to fit precisely without heating, then manufacturing precision must be very high, but this increases manufacturing complexity
Solution Approach 1:
The patent uses thermal expansion to temporarily increase the thrust piece size during assembly. The heating process allows the thrust pieces to expand and be inserted into the bearing cups with standard precision components. After cooling, they contract to achieve the desired tight fit, thereby achieving high manufacturing precision without increasing device or process complexity.
Solution Approach 2:
The patent applies preliminary action by heating the thrust pieces before assembly. This preliminary thermal treatment prepares the thrust pieces for easy insertion into the bearing cups. The pre-heating allows standard-precision components to be assembled without requiring complex adjustment mechanisms or high-precision machining, thus achieving high fitting precision while keeping the manufacturing process simple.
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 method effectively suppresses rattling of yokes relative to the cross shaft while keeping manufacturing costs low by adjusting the thrust piece size through thermal deformation, without necessitating high precision in shape or assembly.
Implementation Method 1
heating and deforming at least one of the thrust pieces to adjust a size of the thrust piece in an axial direction of a corresponding shaft part
Data Source
AI summary
A pin is made of a synthetic resin having an appropriate thermal expansion rate and a low friction coefficient. At a state where respective members configuring a cross shaft universal joint are assembled, a tip portion of the pin is heated and softened, and one yoke is pivotally displaced relative to other yoke. Thereby, it is possible to set a fitting margin of the pin to a bottom inner surface of a bearing cup to an appropriate size and to adjust a shape of an end surface of the pin.