Two-Channel Wheel Speed Sensor in Compact Axle Housing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Smaller axle housings in vehicles lack sufficient space for traditional two-channel wheel speed sensor assemblies, limiting the ability to accurately determine the rotational speed of each wheel, which is crucial for anti-lock and traction control systems.
Innovation Solution
A two-channel wheel speed sensor system is implemented, utilizing a first slotted or toothed circular member mounted to a rotating gear of the differential and a second slotted or toothed circular member on a wheel axle shaft, with sensors connected to a control unit to calculate the rotational speed of each wheel by recording the passage of teeth or slots, allowing for accurate determination of wheel speeds using the formula SWS=2DS−FWS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-channel wheel speed sensor system is implemented in smaller axle housings, then accurate determination of individual wheel speeds is achieved, but the available space for mounting sensor assemblies is insufficient
Solution Approach 1:
The patent implements nesting by placing the first speed sensor assembly inside the differential housing, which itself is housed within the axle housing. This nested arrangement allows the sensor to occupy space within the existing differential assembly rather than requiring additional external mounting space, thereby resolving the space constraint in smaller axle housings while maintaining two-channel measurement capability
Solution Approach 2:
The patent utilizes the radial dimension within the differential housing by mounting the first speed sensor assembly to sense the rotational speed of the differential ring gear. This dimensional approach allows the sensor to be positioned in a location that does not interfere with the axial space required for other differential components, effectively using three-dimensional space optimization to accommodate the sensor in compact housings
2Measurement precision
If speed sensor assemblies are positioned on wheel axle shafts near the wheels, then accurate wheel speed sensing is achieved, but the sensor assembly is exposed to unfavorable conditions that impede function and longevity
Solution Approach 1:
The patent extracts the first speed sensor assembly from the external wheel axle shaft environment and relocates it to the protected interior of the differential housing. By taking the sensor out of the harsh external environment (exposed to weather, road debris, and contamination) and placing it inside the sealed differential housing, the system maintains measurement capability while significantly improving sensor reliability and longevity
Solution Approach 2:
The differential housing serves as an intermediary protective structure between the first speed sensor assembly and the harsh external environment. The housing provides thermal, mechanical, and environmental protection to the sensor, acting as a mediator that shields the sensitive electronic component from unfavorable conditions while still allowing it to perform its measurement function through sensing the differential ring gear rotation
3Area of stationary object
If one-channel wheel speed sensor systems are used in smaller axle housings, then space constraints are satisfied, but the average wheel speed output is of limited use to anti-lock and traction control systems
Solution Approach 1:
The patent applies segmentation by dividing the speed measurement function into two separate sensor assemblies: one sensing the differential ring gear rotation (providing average speed information) and another sensing the wheel axle shaft rotation (providing individual wheel speed information). This segmentation allows the system to capture both average and individual wheel speeds simultaneously, preserving critical information for anti-lock and traction control systems while operating within smaller axle housing constraints
Solution Approach 2:
The first speed sensor assembly mounted on the differential ring gear serves multiple functions: it measures the average rotational speed of the differential, provides reference data for calculating individual wheel speeds, and enables both anti-lock braking and traction control functions. This multi-functionality allows a single sensor placement to deliver comprehensive speed information that would otherwise require separate dedicated sensors, thereby maximizing information utility within limited space
Data Source
AI summary
A wheel speed sensor system for determining the rotational speed of the wheels mounted at the opposite ends of an axle without requiring wheel speed sensor assemblies for each wheel shaft axle. As a result, the speed sensor system of the present disclosure can be housed in small sized or small capacity axle housing such as banjo type housings. In one embodiment, a wheel speed sensor assembly is positioned in the axle housing to determine the speed of one of the wheel axle shafts and a differential speed sensor assembly is positioned in the axle housing to determine the rotational speed of the differential. With these two speed measurements the rotational speed of the other wheel axle shaft can be calculated by a control unit. The wheel and differential speed sensor assemblies can each include a toothed or slotted ring or disk and sensor for sensing the teeth. In each of the wheel and differential speed sensor assemblies, one of the tone ring and sensor can be mounted for rotation with a wheel axle shaft and gear of the differential respectively and the other can be fixedly mounted. The sensors can detect the passage of teeth over time via the relative motion of the teeth and sensor to determine rotational speed.