1. Suction tube preheating
As shown in Figure 521, an air heater is installed in the suction pipe of the Daewoo excavator engine.When the start switch is placed in the preheating position, the current flows through the battery → fuse → B terminal of the start switch → R1 terminal of the start switch → pre The C terminal of the thermal relay→the battery circuit makes the contact of the preheating relay closed. When the preheating relay contact is closed, a large current flows through the battery→battery
Relay→circuit breaker→preheat relay→air heater battery, make the heater's heating wire generate heat for about 19s. After 19s of preheating, the indicator light indicating that the preheating is completed comes on. When the start switch is placed in the start position, current flows to the coil of the preheating relay 6 through the R1 terminal of the start switch, and heating continues.
2. Pre-combustion chamber preheating
As shown in Figure 1522, each cylinder pre-combustion chamber of the engine is equipped with a preheating plug. When the start switch is placed in the preheating position, the current passes through the battery → fuse → B terminal of the start switch → R terminal of the start switch → C terminal of preheating relay→battery, make the contact of preheating relay connected. When the contacts of the preheating relay are connected, the current flow is battery→storage
Battery relay → fuse → preheat relay → preheat plug → battery, and flow through the preheat plug set on each cylinder, the preheat time is about 3.5s, there is a timer in the instrument panel, after the preheat starts After 3.5s, the preheating completion indicator is on.
When the start switch is set to the start position, current flows through the R2 terminal of the start switch and the coil of the preheating relay, and the preheating continues.
