Physical Quantity Sensor Connection Part Slit Design
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Solution Overview
Problem
Existing physical quantity sensors, such as acceleration sensors, face issues with mechanical strength due to stress concentration at connection points, leading to potential damage and reduced reliability under impact conditions.
Innovation Solution
The design incorporates a movable portion with a support beam and connection parts featuring slits that are strategically positioned and shaped to alleviate stress concentration, including first, second, and third slits that are deviated and overlapping to distribute stress more evenly, thereby enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the movable portion is seesaw-rotated with the beam connecting the support portion to the movable portion, then the physical quantity sensor can measure acceleration in the Z axis direction, but relatively large stress is applied to the connection portion between the beam and the support portion or the connection portion between the beam and the movable portion
Solution Approach 1:
The connection part is divided into multiple segments by providing first, second, and third slits that extend in the first direction. These slits segment the connection part into multiple regions, allowing stress to be distributed across multiple locations rather than concentrated at a single connection point between the beam and the movable portion.
Solution Approach 2:
The slits are strategically positioned and sized to create different local properties within the connection part. The first slit has a specific size and position, while the second and third slits have different sizes and positions, creating localized stress distribution patterns that optimize both measurement capability and mechanical strength in different regions of the connection part.
2Measurement precision
If the movable portion is seesaw-rotated, then acceleration measurement is enabled, but the connection portions are easily damaged under impact
Solution Approach 1:
The connection part is divided into multiple segments by providing first, second, and third slits that extend in the first direction. These slits segment the connection part into multiple regions, allowing stress to be distributed across multiple locations rather than concentrated at a single connection point between the beam and the movable portion.
Solution Approach 2:
The slits are designed to absorb and distribute impact stress before it reaches the critical connection points. By creating multiple stress distribution paths through the slits, the structure is prepared in advance to withstand impact forces that may occur during operation, preventing damage to the connection portions.
3Shape
If the connection part connects the first mass part to the second mass part, then the movable portion structure is formed, but stress concentration occurs at the connection portion
Solution Approach 1:
The connection part is divided into multiple segments by providing first, second, and third slits that extend in the first direction. These slits segment the connection part into multiple regions, allowing stress to be distributed across multiple locations rather than concentrated at a single connection point between the beam and the movable portion.
Solution Approach 2:
The slits extend in the first direction (orthogonal to the rotation axis), creating a dimensional approach to stress distribution. By distributing stress along the length of the connection part rather than at a single point, the design transforms a point-stress problem into a distributed stress problem across multiple dimensions of the connection part.
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 effectively reduces stress concentration at connection points, improving the mechanical strength and reliability of the physical quantity sensor, allowing it to withstand impacts without damage and maintain accurate measurements.
Implementation Method 1
each of an electrostatic capacitance between the movable portion and the first fixed detection electrode and an electrostatic capacitance between the movable portion and the second fixed detection electrode changes. Thus, the physical quantity sensor disclosed in JP-A-9-189716 can measure the acceleration in the Z axis direction on the basis of the changes in the electrostatic capacitances.
Data Source
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AI summary
A physical quantity sensor includes a movable portion including a first mass part on one side of a rotation axis, a second mass part on the other side, and a connection part that connects the first mass part to the second mass part. The connection part includes a first slit, a second slit on one side, and a third slit on the other side of the first slit. An axis along the first direction through the center of the first slit is referred to as a first central axis, an axis along the first direction through the center of the second slit is referred to as a second central axis, and an axis along the first direction through the center of the third slit is referred to as a third central axis, each of the second central axis and the third central axis is deviated in a direction of the rotation axis with respect to the first central axis.