Trigger unit mounting structure for wheel position detection system

A trigger unit mounting structure in a wheel position detection system for a vehicle,

• the system including a trigger arrangement for outputting a trigger signal over a magnetic field towards a transceiver attached to each of wheels of the vehicle by comprising a magnetic field type antenna being configured by a core wounded by a coil through which an electric current flows to generate the magnetic field,
• the transceiver receiving the trigger signal, measuring a reception strength of the received trigger signal, and transmitting data of the measured reception strength to a receiver in a body of the vehicle,
• the wheel position detection system thus detecting a wheel position of the each of the wheels based on the data transmitted from the transceiver,
• the trigger arrangement comprising,
• a first trigger unit configured to output a trigger signal to first transceivers individually attached to a right front wheel and a left front wheel;
• and
• a second trigger unit configured to output a trigger signal to second transceivers individually attached to a right rear wheel and a left rear wheel,
• each trigger unit of (i) the first trigger unit and (ii) the second trigger unit being arranged such that a closer-side wheel of each of (i) front wheels and (ii) rear wheels is closer to the each trigger unit than a farther-side wheel of the each of (i) front wheels and (ii) rear wheels,
• the closer-side wheel being accommodated in a tire housing having an internal wall surface facing the closer-side wheel,
• the each trigger unit being arranged at a point J on the internal wail surface, wherein
• a vertical plane A is defined as a side plane of the closer-side wheel directed in a vehicle-length direction and orthogonal to a ground surface being horizontal,
• a horizontal plane B is defined as a plane including the point J and parallel with the ground surface,
• a curve X is defined by intersecting with each other (i) the horizontal plane B and (ii) the internal wall surface,
• a tangent Y is defined at the point J on the curve X,
• an intersecting point K is defined by intersecting with each other the vertical plane A and the tangent Y,
• a line Z is defined by projecting the tangent Y on an intersecting line formed by (i) the vertical plane A and (ii) the horizontal plane B, and
• an angle W as an angle of the internal wall against the side plane of the closer-side wheel is defined at the intersecting point K by (ii) the tangent Y and (ii) the line Z;
• and
• wherein each of the first trigger unit and the second trigger unit is arranged at the point J such that the angle W is within a range between 5 degrees to 25 degrees.