Appliance Door Hinge Cylindrical Cam Spring Preload Adjustment
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Solution Overview
Problem
Existing door hinges for domestic appliances, such as dishwashers, require frequent adjustments of elastic elements to balance varying door weights and materials, leading to laborious and imprecise adjustments, which can result in unbalanced systems and malfunctioning doors.
Innovation Solution
A hinge design featuring a cylindrical cam device that adjusts the preloading of a helical spring by rotating cams to vary the elastic reaction force, allowing for quick and precise balancing of doors through a simple operation, incorporating a friction element for enhanced stability and weight coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If screw means with reduced thread angle are used to adjust spring preloading, then stable adjustment is achieved, but the number of rotations required increases making adjustment laborious and time-consuming
Solution Approach 1:
The patent replaces the traditional screw thread mechanism with a cylindrical cam mechanism. The cylindrical cam has a curved profile that converts rotational motion into linear displacement of the spring preload adjustment. This curved surface mechanism requires significantly fewer rotations (typically 3-5 rotations) compared to a fine-threaded screw to achieve the same adjustment range, while maintaining stable and precise positioning through the cam's profile geometry.
2Measurement precision
If fine thread angle is used for stable adjustment, then adjustment precision is improved, but the complexity of achieving exact replication in both hinges increases
Solution Approach 1:
The cylindrical cam's curved profile provides a predetermined, repeatable relationship between rotation angle and spring preload displacement. This geometric precision allows for easy replication of the same adjustment in both hinges by simply rotating the cam to the same angular position, eliminating the difficulty of replicating exact screw thread adjustments.
Solution Approach 2:
The cam profile is designed with specific geometric parameters that directly control the preload adjustment characteristics. By changing the cam profile geometry (radius, curvature, pitch), the adjustment range and precision can be optimized without increasing mechanical complexity, and the same profile can be replicated in both hinges for consistent balancing.
3Ease of operation
If cylindrical cam device is used to adjust spring preloading, then adjustment speed and ease are improved, but the device complexity increases
Solution Approach 1:
The cylindrical cam mechanism is integrated into the existing hinge structure by combining it with the spring mounting assembly. The cam is positioned such that its rotation directly adjusts the spring preload through the existing lever and connection points, merging the adjustment function with the structural components rather than adding a completely separate mechanism.
Solution Approach 2:
The cylindrical cam acts as an intermediary element that translates simple rotational input into the linear preload adjustment of the spring. This intermediary mechanism provides mechanical advantage and precise control while maintaining a relatively compact and integrated structure that does not significantly increase overall hinge complexity.
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
Enables fast and effective adjustment of the elastic reaction force, accommodating a wide range of door weights and materials, ensuring stable and balanced door operation with reduced complexity and cost.
Implementation Method 1
a spring (7) which defines, for the hinge (1), a respective elastic element designed to generate, with a relative deformation, an elastic reaction force
Implementation Method 2
a cylindrical cam device (16) interposed between the spring (7) and the second element (3)
Implementation Method 3
incorporating a friction element for enhanced stability and weight coverage
Data Source
AI summary
A hinge for doors of domestic appliances, comprising a first element and a second element pivoted to each other and movable relative to each other in tilting fashion, the first and second elements being fixable one to a frame and the other to a door of an electrical household appliance, for making the door movable with respect to the frame between a closed position and an open position, a lever for connection between the first and the second closing elements, an elastic element connected to the lever and designed to generate with its own deformation a force of elastic adjustment designed to compensate at least partially the weight force of the door during the opening or closing of the door, means for adjusting the intensity of the elastic reaction force.