Vehicle Seat Load Detection Device Strain Measurement
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Solution Overview
Problem
Existing load detection devices for vehicle seats face issues with dimensional errors leading to internal stress and reduced detection accuracy, increased part count, weight, and assembly complexity, which affect the reliability and cost-effectiveness of the system.
Innovation Solution
A load detection device with a strain generating body and strain gauges, supported by first and second lower bushes and a connecting shaft, featuring a bracket member with a connecting portion and fixing holes that allow for relative movement in the lengthwise direction while restricting movement intersecting with it, ensuring accurate strain measurement without additional washers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two fixing portions are press-fitted into respective holes with integral connection, then structural rigidity is improved, but internal stress is generated due to dimensional errors
Solution Approach 1:
The second fixing hole is designed as an elongated hole that allows dynamic adjustment and absorption of dimensional differences between the two fixing portions and the holes. This dynamic clearance prevents internal stress generation while maintaining structural integrity, resolving the contradiction between rigidity and detection accuracy.
Solution Approach 2:
The fixing system is segmented into two independent fixing portions that can be adjusted relative to each other. The first fixing portion uses a standard press-fit hole while the second uses an elongated hole, allowing independent positioning to accommodate dimensional variations and prevent stress concentration.
2Reliability
If a washer is added to securely join fixing portions, then connection reliability is improved, but part count and assembly complexity increase
Solution Approach 1:
The washer component is completely removed from the design. Instead of using a washer to secure the fixing portions, the invention uses the elongated hole configuration itself to provide secure joining while accommodating dimensional variations, thereby reducing part count and assembly complexity.
Solution Approach 2:
The elongated hole configuration performs the dual function of both securing the fixing portion and accommodating dimensional errors, eliminating the need for additional components like washers. The structure serves itself by using its geometric form to achieve both connection and tolerance absorption.
3Measurement precision
If additional washers are used to prevent looseness, then detection accuracy is improved, but weight and cost increase
Solution Approach 1:
The washer used to prevent looseness is removed from the design. The elongated hole configuration inherently prevents looseness in the direction intersecting with the lengthwise direction while allowing movement in the lengthwise direction, achieving the same function without additional weight.
4Ease of manufacture
If fixing portions are forced to fit into holes, then assembly ease is improved, but internal stress is generated
Solution Approach 1:
The second fixing hole is designed as an elongated hole that provides dynamic clearance, allowing the fixing portion to be easily assembled without forcing while preventing internal stress generation. The elongated shape accommodates dimensional errors naturally during assembly.
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 configuration enhances detection accuracy, reduces part count and weight, and simplifies assembly, thereby improving the reliability and cost-effectiveness of the load detection system.
Implementation Method 1
a strain gauge being attached on the strain generating body between the first end hole and the second end hole
Implementation Method 2
the second fixing hole being formed to be fitted onto the second end shaft portion of the second fixing member in a manner that the second fixing hole includes a degree of freedom of a movement of the second fixing hole relative to the second end shaft portion of the second fixing member in a lengthwise direction of the strain generating body and in a manner that a movement of the second fixing hole relative to the second end shaft portion in a direction intersecting with the lengthwise direction is restricted
Data Source
AI summary
A load detection device for a vehicle seat includes a strain generating body including a first end hole, a second end hole and a strain gauge, a first fixing member including a first middle shaft portion and a first end shaft portion, a second fixing member including a second middle shaft portion and a second end shaft portion, a bracket member including first and second fixing portions connected to each other with a connecting portion, first and second fixing holes, the first end shaft portion is press-fitted into the first fixing hole, the second fixing hole is fitted onto the second end shaft portion in a manner that the second fixing hole includes a degree of freedom of a movement thereof in a lengthwise direction and a movement thereof in a direction intersecting with the lengthwise direction is restricted, and a connecting member.