Wheel Speed Sensor Axle Passageway Design
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Solution Overview
Problem
Existing wheel speed sensing systems for anti-lock braking systems (ABS) in heavy-duty vehicles are costly and prone to inaccurate measurements due to the need for external wiring and vulnerability of components during maintenance, as well as sensitivity to bearing adjustments and tone wheel wobble, leading to potential system shutdowns.
Innovation Solution
A wheel speed sensing system where a non-rotating axle with a passageway accommodates an electrical connection between a coaxially disposed sensor and electronic control module (ECM), using a rotating magnet and sensor to generate a signal proportional to wheel speed, eliminating the need for external wiring and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stationary magnetic sensor is mounted on the axle with external wiring to the ECM, then wheel speed sensing is achieved, but installation cost and maintenance complexity increase due to costly modifications and external wire routing
Solution Approach 1:
The patent extracts the magnetic sensor from its traditional stationary position on the axle and relocates it to rotate with the wheel hub. This extraction allows the sensor to be positioned optimally near the tone wheel while eliminating the need for external wiring, as the signal is generated directly at the rotating assembly where the ECM can access it through the wheel cover opening.
Solution Approach 2:
The patent merges the magnetic sensor with the wheel hub assembly, causing them to rotate together. This combination eliminates the need for separate mounting structures and external wiring connections, reducing installation complexity while maintaining sensing reliability. The sensor and wheel hub become an integrated rotating unit.
2Ease of repair
If the tone wheel is placed inside the wheel cover for easy access, then maintenance is simplified, but the tone wheel becomes vulnerable to damage during wheel cover removal
Solution Approach 1:
The patent changes the spatial arrangement by positioning the magnetic sensor at a different radial distance from the tone wheel, allowing the sensor to be mounted on the wheel hub while the tone wheel remains in the wheel cover. This dimensional adjustment maintains easy access for maintenance while protecting the tone wheel from direct exposure during wheel cover removal.
3Ease of manufacture
If bearing adjustment is varied to accommodate manufacturing tolerances, then ease of assembly improves, but axial movement of the wheel hub affects the gap between the tone wheel and sensor
Solution Approach 1:
The patent applies dynamics by making the magnetic sensor rotate with the wheel hub rather than remaining stationary. This dynamic positioning ensures that the sensor maintains a consistent rotational relationship with the tone wheel regardless of bearing adjustments or axial hub movement, eliminating gap variation issues while preserving manufacturing flexibility.
4Measurement precision
If the gap between the sensor and tone wheel is maintained precisely, then measurement accuracy improves, but manufacturing cost and maintenance cost increase
Solution Approach 1:
The patent implements self-service through the dynamic rotation of the magnetic sensor with the wheel hub. The rotating sensor automatically maintains its optimal positioning relative to the tone wheel during wheel rotation, self-correcting for any manufacturing tolerances or bearing adjustments without requiring precise initial gap setting or ongoing maintenance intervention.
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 solution reduces installation and maintenance costs while providing accurate and reliable wheel speed sensing, minimizing the risk of system shutdowns and improving the performance of ABS systems by maintaining consistent signal integrity.
Implementation Method 1
As the tone wheel passes the sensor, the resulting variations in magnetic flux produce a signal, the frequency of which is a function of the angular velocity of the wheel
Data Source
AI summary
An improved speed sensing system is disclosed for a machine, such as a truck, that has an axle with an end and an axis. The machine further includes a sensor non-rotatably coupled to the end of the axle and coaxial with the axis. A wheel hub is rotatably coupled to the axle and a wheel cover is coupled to the wheel hub. The machine further includes a magnet coaxially disposed with the axis and coupled to the wheel cover for rotation about the axis as the wheel rotates. The sensor generates signals based on the rotational speed of the magnet and the wheel. For non-rotating axles that are solid or include solid spindles, a passageway for a communication line between the sensor and electronic control module (ECM) may be easily drilled thereby making the disclosed system easy to add to an existing machine or vehicle.