Kubota WG972-E2 Workshop Manual page 66

WG972-E2, DF972-E2, WSM
■ Charging Machanism
The charging mechanism is described in four
sections:
1. When key switch is "ON".
2. At starting
3. In charging
4. Over-charge protection
(1) GEN: Magnet type AC generator
(2) LAMP: Charge indication lamp (not included in the basic
engine)
(3) KEY SW: Key switch
(4) BATT: Battery (not included in the basic engine)
(5) Blue: GEN connecting terminal
(6) Red: BATT + connecting terminal
(7) Yellow: BATT voltage test terminal
(8) Black: BATT - connecting terminal
(9) Green: LAMP connecting terminal
S1, S2: Output control / rectification thyristor (SCR)
D1, D2: Output rectifying diode
D3, D4: GEN generation detecting diode
D5, D6: Protection diode for wrong connecting of BATT
Z1: BATT terminal voltage setting diode
Q1: GEN generation detecting transistor
Q2: LAMP on / off transistor
Q3: Gate current control transistor
Q4: BATT voltage detecting transistor
1. When Key Switch is "ON"
When the engine is at standstill with key switch set at
position 1, the circuit functions to light LAMP, as shown
in figure (A). With key switch at position 1, current flows
to base of Q2 through the route of BATT → emitter / base
of Q2 → R1 → D6 → BATT and collector of Q2 is then
turned on. As a result, current also flows to LAMP
though the route of BATT → emitter / collector of Q2 →
D5 → LAMP → BATT lighting LAMP to indicate that
charging is not carried out. At this time, though current
flows to base of Q3 thorugh the route of BATT → emitter
/ base of Q3 → R2 → D6 → BATT, collector of Q3 has no
current because GEN is stationary.
2. At Starting
When key switch is turned to position 2, coil of starter
relay is energized and starter starts engine. GEN also
starts generation for charging and LAMP is turned off.
In detail, with GEN starting, current flows to base of
Q1 through the route of GEN → D1 → emitter / base of
Q1 → R4 → D4 → GEN, or GEN → D2 → emitter / base
of Q1 → R4 → D3 → GEN, and therefore current also
flows through Q1, shortcircuiting emitter and base of Q2.
. As a result, base current of Q2 is interrupted, Q2 is
turned off and accordingly current to LAMP is also
interrupted.
M-26
GASOLINE / LPG ENGINE
W1034331
W1035327
W1035571
KiSC issued 01, 2006 A