Testing; Checking The Cambox Reference Value - Bosch CAM 847 Maintenance Instructions Manual

8.

Testing

8.1 Checking the CAMBox reference
value
UI / UP checking with the CAM 847 involves actuating
the solenoid valve at a pre-defined cam angle for
a certain time. For this purpose, the CAM 847
measurement system must be able to detect the
current position of the CAMBox cam. This is effected
by way of the phase encoder B20 and the CAMBox
reference value.
The CAMBox reference value (CAM
at the factory and represents the angular distance of
the phase encoder pulse (P
cam (0° ), also referred to as 0° cam.
CAM
CAM
P
Imp
Fig. 10: CAMBox reference value for one cam revolution
CAM CAMBox reference value
Ref
P Phase encoder pulse
Imp
0° 0° cam position
CAM
i
The CAMBox reference value is entered once only
in the system software on initial start-up of the
CAMBox and stored.
The upward motion (lift) takes place at the 0° cam
position. This is also the bottom dead center of the
cam. The following illustration shows the lift profile for
two cam revolutions.
0°
CAM
0
0°
CAM
Umdrehung / Rotation
Fig. 11: Cam lift profile for two revolutions
0° 0° cam position
CAM
Robert Bosch GmbH
) is determined
Ref
) from the 0° circle of the
Imp
Ref
458830_12pa
0°
CAM
458830_11pa
0°
CAM
Testing | CAM 847 | 43
A change in the CAMBox reference value, e.g. as a result
of replacing the phase encoder, also shifts the 0° cam
position and thus alters the lift to be expected. Such a
shift has an effect on the quantity when checking the
test specimen.
On checking the CAMBox reference value, the cam
of the CAMBox is turned by 25.5° out of the 0° cam
position (refer to Fig. 12 A) into the reference point
position (refer to Fig. 12 B). The lift is measured in
this reference point position with a dial gauge. The lift
must be 7.9 ±0.015 mm at the reference point. If the
value is outside the checking tolerances, the angular
distance (CAMBox reference value) between the phase
encoder pulse and 0° cam has changed and must be
re-determined.
A)
00,000
1
2
3
Fig. 12: CAMBox cam with dial gauge
A) Cam in 0° cam position
B) Cam in reference point position
1 0° cam position
2 Cam zero circle range
3 Direction of rotation of cam
4 Reference point position
en
B)
07,900
4
1
3
458830_9pa
|
1 689 975 209 2012-07-12