Three-Point Hitch Bearing Bolt Force Measurement
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Solution Overview
Problem
Conventional force measuring bolts in three-point hitches face challenges such as temperature dependency and difficulty in distinguishing between changes in magnetic fields due to temperature or mechanical forces, and issues with detecting a 'zero point' due to plastic deformation, leading to inaccurate force measurements.
Innovation Solution
A three-point hitch design featuring a cylindrical bearing bolt with a cavity containing a cylindrical measuring element equipped with multiple strain gauge sensors arranged axially, radially, or at angles to match the force direction, allowing for precise force measurement and temperature compensation, with sensors positioned to detect both magnitude and direction of forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force measuring bolt with magnetic field sensor is used in a three-point suspension, then force detection capability is provided, but temperature changes cause material property changes that alter the magnetic field, making it impossible to distinguish between temperature-induced and force-induced field changes
Solution Approach 1:
The measurement function is segmented into two independent sensor types: strain gauges for measuring mechanical force/deformation and magnetic field sensors for detecting magnetic flux changes. This segmentation allows each sensor type to specialize in its measurement domain, with strain gauges providing temperature-compensated force measurements and magnetic sensors detecting only force-induced magnetic field changes, thereby eliminating temperature interference in the force measurement.
Solution Approach 2:
The patent introduces a coil wound around the bearing bolt as an intermediary element. This coil acts as a mediator between the bearing bolt and the magnetic field sensor, converting mechanical force into magnetic flux changes that can be detected by the magnetic field sensor. The coil serves as a transducer that translates mechanical deformation into magnetic field variations, enabling indirect force measurement through magnetic field changes.
2Measurement precision
If conventional force sensors are used in three-point hitches, then force detection is enabled, but the sensors cannot distinguish between magnetic field changes caused by temperature or mechanical forces
Solution Approach 1:
The measurement function is segmented into two independent sensor types: strain gauges for measuring mechanical force/deformation and magnetic field sensors for detecting magnetic flux changes. This segmentation allows each sensor type to specialize in its measurement domain, with strain gauges providing temperature-compensated force measurements and magnetic sensors detecting only force-induced magnetic field changes, thereby eliminating temperature interference in the force measurement.
Solution Approach 2:
The patent implements a feedback mechanism where the strain gauge measurements are used to compensate for temperature effects on the magnetic field sensor readings. By continuously monitoring the strain gauge output and using it to adjust or correct the magnetic field sensor signals, the system maintains accurate force measurements despite temperature variations. This feedback loop ensures that temperature-induced magnetic field changes are distinguished from force-induced changes.
3Measurement precision
If bearing bolts are designed with cavities for sensors, then measurement capability is added, but the cavity structure and sensor arrangement must be optimized to ensure accurate force detection
Solution Approach 1:
The patent merges multiple functions into the bearing bolt structure: it serves as both a mechanical bearing element and a force sensor housing. The cavity within the bearing bolt is designed to accommodate both strain gauges and magnetic field sensors, combining structural support and measurement functions in a single integrated component. This merging reduces the number of separate parts and simplifies the overall system architecture.
Solution Approach 2:
The bearing bolt is designed as a multi-functional component that simultaneously provides mechanical support, houses sensors, and facilitates force measurement through multiple sensing mechanisms. The universal design allows the same bearing bolt structure to accommodate different types of sensors (strain gauges and magnetic field sensors) and perform both structural and measurement functions, reducing system 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 robust and accurate detection of forces acting on the bearing points, allowing for reliable measurement of forces and their direction, even under varying temperature conditions, and prevents false readings due to plastic deformation.
Implementation Method 1
The sensors are designed as strain gauges and also being arranged axially or radially or at an angle to the axial and radial direction on or in the bearing bolt
Implementation Method 2
the bearing bolt has the multiple sensors arranged in parallel planes or on an end face of the measuring element, with one of the parallel planes or the end face rotating several to one another or arranged orthogonally
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
The invention relates to a three-point linkage (1), in particular for a tractor, a drivable work machine, a construction machine, a crane or the like, which is designed for coupling of an attachment apparatus and has at least one bearing point (17, 18) having a bearing bolt (19, 20, 21, 22, 23, 28) having a sensor (36, 37, 43, 44, 45, 49, 50, 53, 56, 59, 62, 63, 67, 68, 68, 69, 71, 78), from which the sensor signal is a measure of a force acting on the bearing point (17, 18), wherein the sensor (36, 37, 43, 44, 45, 49, 50, 53, 56, 59, 62, 63, 67, 68, 68, 69, 71, 78) is arranged axially or radially or obliquely with respect to the axial and radial direction on or in the bearing bolt (19, 20, 21, 22, 23, 28).