Auto Glow Circuit - Kubota u15-3 Workshop Manual

WSM U15-3
i. Auto glow circuit
Key SW
ON
OFF
50A
Battery
1. Function
1. The glow controller receives a water temperature sensor signal or a key switch start position signal and
makes the signal voltage (1) drop to the ground level. Now the current starts flowing to the relay coil.
(NOR signal circuit)
2. Turn the key switch from the OFF to ON position, and the glow relay is kept on for the time "t" as shown
in Fig. 2 (Function chart) to light up the glow lamp.
3. While the key switch is set at the ST position, the glow relay is turned on again to light up the glow lamp.
4. As indicated in Fig. 3 (Timer curve), the pre-glow time (glow lamp-on time) "t" is compensated depending
on the water temperature.
5. Once the current flows to the relay coil, the battery voltage starts flowing to the glow plug.
Reference: NOR logic circuit
Water temp sensor signal
H
H
L
L
The NOR logic circuit is a composite circuit of OR gate and NOT gate.
ST
5A
Water tempt sensor
Key SW ST signal
OR
H H
L H
H H
L L
Key on
ON
OFF ST OFF
Glow relay
OR
t
Auto glow controller
H: High level, 12V
Indicates that a signal voltage
is applied.
L: Low level, 0V
L
Indicates that no signal voltage
is applied or that the terminal
L
is grounded.
L
H
II-134
Key st
ON
ST
Glow plug
Glow lamp