Heavy Duty Riser Hinge Asymmetric Camming System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heavy-duty riser hinges used on commercial refrigerators do not lift doors quickly enough to avoid floor irregularities due to insufficient lifting force and bearing contact surface, leading to premature wear and reduced service life.
Innovation Solution
A riser hinge design featuring a strap assembly with a camming system that includes asymmetrically positioned cam lobes and cam follower ridges, providing increased lifting force and extended contact surfaces to enhance door clearance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a conventional cam lifting configuration is used, then the hinge structure is simple, but the lifting force is insufficient and the door cannot clear floor irregularities
Solution Approach 1:
The patent applies asymmetry by providing cam lobes with different radii and asymmetrically positioned cam follower ridges. The first cam lobe has a different radius than the second cam lobe, and the ridges are positioned asymmetrically to engage with different lobes during door opening. This asymmetric configuration optimizes the distribution of lifting force throughout the door opening arc, providing sufficient lifting capability to clear floor irregularities while maintaining structural efficiency.
2Reliability
If the bearing contact surface on the cam is limited, then the cam structure remains compact, but the plastic cam material cold flows resulting in damage and short service life
Solution Approach 1:
The asymmetric cam lobe design with different radii distributes the bearing contact area more effectively across the cam structure. The varying radii create different contact zone characteristics that reduce stress concentration and minimize cold flow of the plastic material, thereby extending service life without requiring a uniformly larger cam structure.
Solution Approach 2:
The patent transitions from a single-radius cam design to a multi-radius asymmetric cam design, adding dimensional complexity to the cam profile. This dimensional change allows for optimized contact surface distribution that reduces material stress and prevents cold flow while maintaining a compact overall structure.
3Speed
If the camming system provides sufficient lifting force, then the door clears floor irregularities, but the cam structure becomes more complex
Solution Approach 1:
The asymmetric cam lobes with different radii are strategically designed to provide optimized lifting force distribution that achieves sufficient door lifting speed. The asymmetric configuration allows the cam mechanism to deliver high lifting force during the critical initial door opening phase while maintaining a relatively compact structure compared to symmetric designs that would require larger dimensions to achieve the same performance.
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 asymmetric camming system effectively lifts the door to clear floor irregularities, extends the door's opening range, and ensures reliable automatic closing, thereby improving service life and operational efficiency.
Implementation Method 1
This is in the form of a camming arrangement in which the barrel of the hinge mounted to the door rides up a camming surface as the door swings open, thereby lifting the door
Implementation Method 2
which use gravity to assist in the closing of the door
Data Source
AI summary
A riser hinge (10) is disclosed which includes a mounting flange assembly (12) pivotally coupled to a strap assembly (15). The strap assembly includes a camming assembly (27) having a multi-lobed cam 28 with a large lobe (38) and a small lobe (39). The lobes have a top bearing surfaces which extends to a flat dwell surface. The large lobe top dwell surface (41) is of a select size (arcuate length) which is longer than that of the small lobe top dwell surface (44). The camming assembly also includes a cam follower (56) having two cam following ridges (69). The asymmetrical configuration of the grooves creates a first, large ridge (70) and a second, small ridge (71). The bottom bearing surface (77) of the small ridge rides upon the top bearing surface of the small lobe. Similarly, the bottom bearing surface (73) of the large ridge rides upon the top bearing surface of the large lobe.