Two-channel wheel speed sensor system

A two wheel speed sensor system for obtaining the rotational speed of a wheel mounted at an end of a left wheel axle shaft and a wheel mounted at an end of a right wheel axle shaft, the sensor system comprising:

• a. a banjo-type axle housing enclosing a differential having a gear set and portions of a left and right wheel axle shafts connected to the differential;
• b. a first speed sensor assembly positioned within a central cavity of the banjo-type axle housing, the first speed sensor assembly having a first sensor and a first ring or disk including teeth spaced about the perimeter of the first ring or disk, one of the first ring or disk and the first sensor mounted on a gear of a differential gear set for rotation therewith and the other one of the first ring or disk and the first sensor fixedly mounted, the first sensor detecting a passing of each of the teeth and connected to a control unit, the control unit recording output of the first sensor over time to calculate a speed of rotation of the gear of the differential gear set (DS);
• c. a second speed sensor assembly positioned within the central cavity of the banjo-type axle housing, the second speed sensor assembly having a second sensor and a second ring or a disk including teeth spaced about the perimeter of the second ring or disk, one of the second ring or disk and the second sensor mounted on one of the wheel axle shafts for rotation therewith and the other one of the second ring or disk and the second sensor fixedly mounted, the second sensor detecting a passing of each of the teeth and connected to a control unit, the control unit recording output of the second sensor over time to calculate a speed of rotation of one of the wheel axle shaft (FWS);
• wherein each of the first and second rings or disks of the first speed sensor assembly and the second speed sensor assembly is a tone ring including teeth having magnetic properties and each of the first and second sensors of the first sensor assembly and the second speed sensor assembly operates by sensing the magnetic properties of the respective teeth that produce a voltage when the teeth of the tone ring pass each of the sensors;
• and
• wherein the control unit calculates a speed of rotation of the other one of wheel axle shafts (SWS) using the following formula:
• SWS=2DS−FWS, and wherein the speed of rotation of the wheel axle shafts is equal to the speed of the respective wheel.

A method of determining the rotational speed of a first wheel mounted at one end of an axle and a second wheel mounted at an opposite end of the axle, the method comprising:

• a. attaching a first slotted or toothed ring or disk to a gear of a differential gear set and positioned in the banjo-type axle housing;
• b. attaching a first sensor to a stationary component and positioned adjacent to the slotted or toothed portion of the first ring or disk and in a central cavity of the banjo-type axle housing, the first sensor capable of sensing a passage of each of the slots or teeth of the first ring or disk;
• c. attaching a second slotted or toothed ring or disk to a rotatable portion of a second wheel axle shaft and positioned in the central cavity of the banjo-type axle housing;
• d. attaching a second sensor to a stationary component and positioned adjacent the slotted or toothed portion of the second ring or disk and in the central cavity of the banjo-type axle housing, the second sensor capable of sensing a passage of each of the slots or teeth of the second ring or disk, wherein the teeth of the first and second rings or disks have magnetic properties and the first and second sensors operate by sensing changes in a magnetic field or flux that produce a voltage when the teeth of the first and second rings or disks pass the first and second sensors;
• e. connecting the first and second sensors to a control unit for recording the passage of slots or teeth of the first and second rings or disks per unit of time to calculate a speed of rotation of the first wheel axle shaft referred to as FWS and a speed of rotation of the gear of the differential gear set referred to as SD;
• and
• f. calculating the speed of rotation of a second wheel axle shaft referred to as SWS according to the following formula:
• SWS=2SD−FWS, wherein the speed of rotation of the first wheel axle shaft and the second wheel axle shaft is equal to the speed of rotation of the first wheel and second wheel, respectively.