2000 Sep 05

7

Philips Semiconductors

Product specification

Rotational speed sensor

KMI15/4

Mounting conditions

The recommended sensor position in front of a gear wheel

is shown in Fig.15. Distance ‘d’ is measured between the

sensor front and the tip of a gear wheel tooth. The KMI15/4

senses ferrous indicators like gear wheels in the

± y

direction only (no rotational symmetry of the sensor); see

Fig.2. The effect of incorrect mounting positions on

sensing distance is shown in Figs 11, 12 and 13.

The symmetrical reference axis of the sensor corresponds

to the axis of the ferrite magnet.

Environmental conditions

Due to eddy current effects the sensing distance depends

on the tooth frequency (see Fig.17). The influence of gear

wheel module on the sensing distance is shown in Fig.16.

Gear Wheel Dimensions

Note

1. For conversion from ASA to DIN: m = 25.4 mm/DP;

p = 25.4 mm

× CP.

SYMBOL

DESCRIPTION

UNIT

German DIN

z

number of teeth

d

diameter

mm

m

module m = d/z

mm

p

pitch p =

π× mmm

ASA; note1

PD

pitch diameter (d in inch)

inch

DP

diametric pitch DP = z/PD

CP

circular pitch CP =

π/DP

inch

Fig.10 Gear wheel dimensions.

handbook, halfpage

pitch

pitch

diameter

MRA964

pitch = module

×π

module

pitch diameter

number of teeth

------------------------------------------

=

Fig.11 Sensing distance as a function of positional

tolerance in the y-axis; typical values.

handbook, halfpage

1

2

4

3

01

2

3

4

0

d

(mm)

MBD840

d

y (mm)

y

f t