Vehicle Seat Load Sensor Mounting With Leaf Spring Load Isolation
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Solution Overview
Problem
Conventional passenger weight measurement devices for vehicle seats face challenges in accurately measuring weight due to dimension and assembling position errors, which result in initial load distortion and interference with load cell measurements, particularly when using a parallelogram linking mechanism and compression type load cells.
Innovation Solution
The solution involves a passenger weight measurement device with a pair of slide rails and load cells arranged at four corners, where two load sensors on one diagonal line are movable and the other two are fixed, and a leaf spring mechanism is used to absorb distortion and prevent initial load application on the load sensors, ensuring accurate weight measurement without increasing the number of components or altering the seat structure significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a load sensor is disposed between the vehicle floor and the vehicle seat to measure passenger weight, then weight measurement function is achieved, but dimension error and assembling position error occur causing very low distortion and initial load on the sensor, making accurate measurement difficult
Solution Approach 1:
A parallelogram linking mechanism is introduced as an intermediary between the load sensor and the seat assembly. This mechanism includes linking members connected to the seat bracket and slide rails, forming a parallelogram structure that accommodates dimensional and positioning variations during assembly while transmitting only the vertical load to the load sensor, thereby eliminating initial loads and improving measurement accuracy
Solution Approach 2:
The invention changes the structural parameters of the connection system by introducing a parallelogram mechanism with specific geometric relationships. The linking members are designed with specific lengths and connection points that maintain parallelism between opposite sides, allowing the system to absorb assembly errors through geometric constraints rather than requiring precise dimensional control
2Measurement precision
If a parallelogram linking mechanism is disposed between the pair of slide rails and the seat bracket to simplify load characteristics, then load sensor accuracy is improved, but the number of components such as linking members is increased
Solution Approach 1:
The seat bracket is designed to serve multiple functions: it connects the seat cushion to the slide rails, provides mounting points for the parallelogram linking mechanism, and transmits loads to the load sensor. By making the seat bracket multi-functional, the invention reduces the need for separate dedicated linking members while maintaining the parallelogram mechanism's load-isolating function
3Measurement precision
If the parallelogram linking mechanism is disposed between the pair of slide rails and the seat bracket, then load characteristics are simplified, but it becomes difficult to set the height from the vehicle body floor to the upper surface of the seat cushion equal to or less than a certain height
Solution Approach 1:
The parallelogram linking mechanism is designed with movable connections that allow dynamic adjustment of the seat height. The linking members can rotate at their connection points, enabling the seat to be positioned at different heights while maintaining the parallelogram geometry. This dynamic capability allows the system to achieve both accurate load measurement and compact seat height configuration
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 suppresses initial load generation during assembly, maintains load sensor rigidity, and prevents unnecessary force application on the load cells, thereby enhancing the accuracy of passenger weight measurement while maintaining the structural integrity and simplicity of the seat framework.
Implementation Method 1
a leaf spring mechanism to absorb distortions and prevent initial loads
Data Source
AI summary
There is disclosed a passenger's weight measurement device for a vehicle seat, capable of suppressing generation of an initial load. The passenger's weight measurement device includes an upper rail disposed to be movable back and forth on a lower rail fixed to a vehicle floor; a load sensor fixed on the upper rail; and a frame disposed on the load sensor and below a vehicle seat, wherein a rod extends from the load sensor to penetrate the frame and to be inserted into an insertion hole formed in a center of a leaf spring, the leaf spring is curved into an angle shape to separate the center of the leaf spring from the frame, a nut is engaged with the rod on the leaf spring, and both hems of the leaf spring abut on the frame in a state that the leaf spring is fastened by the nut.