Patent ID: 11872856
Assignee: DENSO CORPORATION
Field: Measurement (Instruments)
Classification: CPC B  G | IPC B  G

Claim 6:
7. A tire pneumatic pressure monitoring system comprising:
a wheel position detection apparatus to be applied to a vehicle including a vehicle body attached with a plurality of travelling wheels, each of the travelling wheels having a tire,
wherein the wheel position detection apparatus includes:
a plurality of transmitters each of which is configured to be attached to a corresponding traveling wheel in the travelling wheels; and
a receiver configured to be disposed at the vehicle body,

wherein each of the transmitters includes:
an acceleration sensor configured to output a detection signal according to an acceleration including a gravitational acceleration component being varied by a rotation of the corresponding travelling wheel attached with the each of the transmitters; and
a first controller configured to create a frame including unique identification information, and transmit the frame in response to the receiver outputting a transmission command,

wherein the receiver includes a second controller configured to execute a wheel position detection, in response to receiving the frame transmitted from the each of the transmitters, through:
identifying, from each set of the unique identification information included in the frame, the corresponding travelling wheel attached with the each of the transmitters having transmitted the frame; and
registering the travelling wheels in association with the unique identification information of the each of the transmitters attached to the corresponding travelling wheel in the travelling wheels,

wherein the second controller is further configured to:
acquire an edge number of a gear or a tooth number of the gear based on a detection signal of a wheel velocity sensor for detecting a passage of teeth of the gear rotating in coordination with the corresponding travelling wheel, the gear having a circumferential surface with tooth portions and a portion between the tooth portions to alternatively exhibit different magnetoresistance values, the tooth portions being conductors;
detect suitable timing based on difference in the edge number among the travelling wheels or difference in the tooth number among the travelling wheels; and
output the transmission command to the each of the transmitters attached to the corresponding travelling wheel, in response to detecting the suitable timing,

wherein, in a situation where an arbitrary circumferential position of the corresponding travelling wheel centered with respect to a central axis of the corresponding travelling wheel attached with the each of the transmitters having the first controller forms an angle of zero degrees, the first controller is configured to:
detect a presence angle being an angle where the each of the transmitters is present with respect to the arbitrary circumferential position, based on the gravitational acceleration component included in the detection signal of the acceleration sensor; and
transmit the frame at a timing in which the presence angle reaches a predetermined angle, in response to the second controller outputting the transmission command,

wherein the second controller is further configured to:
set a variation tolerance width based on the edge number or the tooth number at a timing of receiving the frame;
remove at least one of the travelling wheels from candidate wheels respectively attached with the transmitters having transmitted the frame, in a condition that the edge number corresponding to the at least one of the travelling wheels or the tooth number corresponding to the at least one of the travelling wheels is outside of a range of the variation tolerance width at the timing of receiving the frame subsequent to setting the variation tolerance width; and
register remainder of the candidate wheels as the corresponding travelling wheel attached with the each of the transmitters having transmitted the frame,

wherein the each of the transmitters includes a sensing part to output a detection signal according to a pneumatic pressure of the tire included in the each of the travelling wheels, and is configured to store information related to the pneumatic pressure of the tire acquired by executing signal processing on the detection signal of the sensing part, and then transmit the frame to the receiver, and
wherein the receiver detects the pneumatic pressure of the tire included in the each of the travelling wheels, based on the information related to the pneumatic pressure of the tire.