Brake Rotor Tone Ring Insert for ABS Sensor Accuracy
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Solution Overview
Problem
Anti-lock brake systems face performance issues due to irregularities and corrosion of cast teeth in brake rotor assemblies, leading to inaccurate sensor readings and shortened lifespan, as well as high costs associated with machining for accuracy and temperature-related magnetic property changes in cast iron.
Innovation Solution
A brake rotor disc assembly with a tone ring insert comprising a cast iron cylindrical spacer and a powder metal cap with high precision teeth, coated for corrosion resistance, which can be retrofitted into existing systems, providing accurate and durable sensor readings at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If teeth are cast with the rotor, then manufacturing cost is reduced, but manufacturing precision and geometric accuracy deteriorate
Solution Approach 1:
The tone ring is separated from the rotor body, allowing the teeth to be manufactured independently with high precision processes while the rotor can be manufactured separately. This segmentation enables different manufacturing processes to be optimized for each component's specific requirements.
Solution Approach 2:
A dedicated tone ring component serves as an intermediary element that interfaces between the rotor and the ABS sensor. This mediator can be manufactured with high precision using specialized processes while being mounted on the rotor, resolving the conflict between ease of rotor manufacture and precision of teeth.
2Reliability
If coating is applied to the entire rotor including teeth, then corrosion resistance is improved, but magnetic signal strength deteriorates due to coating interference
Solution Approach 1:
Different surface treatments are applied to different regions of the tone ring: the tooth surfaces are left uncoated or minimally coated to preserve magnetic signal generation, while the non-tooth portions receive corrosion-resistant coating. This local differentiation resolves the contradiction between overall corrosion protection and magnetic signal strength.
3Ease of manufacture
If cast iron is used for the rotor, then ease of manufacture and cost are improved, but magnetic properties change with temperature causing signal inaccuracy
Solution Approach 1:
The tone ring is made from a different material than the rotor body, combining the cost-effective cast iron rotor with a tone ring material that has stable magnetic properties across temperature ranges. This composite approach allows each component to have optimized properties for its specific function.
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
The solution offers a more accurate, durable, and cost-effective anti-lock brake system with extended service life by minimizing corrosion and thermal deformation, allowing for precise sensor readings and easy replacement of degraded tone rings.
Implementation Method 1
Many sensors use magnetic pulse generation, which is created as the teeth pass by the sensor. The strength and accuracy of the signal is determined by the magnetic properties of the tone ring and the ring's geometric accuracy.
Data Source
AI summary
A brake rotor assembly for use with an anti-lock braking system. The brake rotor assembly includes a brake rotor having a pair of braking surfaces; a tone ring having a first end having a plurality of spaced sensing formations disposed thereon and a second end for circumferentially contacting a surface of the brake rotor assembly, the first end thermally insulated from the brake rotor; and a snap ring for connecting the tone ring to the brake rotor assembly. A method of forming a brake rotor assembly is also provided.