The glow plug is also called preheating plug. When the diesel engine is cooled during cold weather, the plug provides heat to improve start-up performance. At the same time, the electric plug is required to have the characteristics of rapid temperature rise and persistent high temperature state.
Characteristics of various electric plug Metal electric plug features· Speed preheating time: 3 seconds temperature can reach more than 850 degrees Celsius· Post heating time: After engine starts, the plug maintains temperature (850 ° C) for 180 seconds to reduce contaminants.· Operating temperature: about 1000 degrees Celsius.Ceramic electric plug features· Preheating time: the temperature can reach over 900 degrees Celsius in 3 seconds· Post heating time: After engine starts, the plug maintains temperature (900 ° C) for 600 seconds to reduce contaminants.Schematic diagram of common electric plug structure· Operating temperature: approx. 1150 degrees Celsius.Rapid preheating of metal plug features· Preheating time: the temperature can reach more than 1000 degrees Celsius in 3 seconds· Post heating time: After engine starts, the plug maintains temperature (1000 ° C) for 180 seconds to reduce contaminants.· Operating temperature: about 1000 degrees Celsius·PWM signal control Quick preheating ceramic plug features· Preheating time: the temperature can reach more than 1000 degrees Celsius in 2 seconds· Post heating time: After engine starts, the plug maintains temperature (1000 ° C) for 600 seconds to reduce contaminants.· Operating temperature: approx. 1150 degrees Celsius·PWM signal control Diesel engine start preheating plug There are several different types of preheating plugs, the most widely used are the following three: regular; Temperature control type (including preheating plug for conventional preheating device and new super preheating device); Low voltage type for conventional super preheater. A preheating plug is screwed into each combustion chamber wall of the engine. The preheating plug housing has a preheating plug resistance coil mounted in a tube. An electric current passes through a resistance coil, heating the tube. The tube has a large surface area and can generate more heat. The tube is filled with insulating material to prevent the resistance coil from contacting the inner wall of the tube due to vibration. The rated voltage of various preheating plugs varies depending on the battery voltage used (12V or 24V) and the preheating device. Therefore, it is important to use the correct type of preheating plug, the use of incorrect preheating plug will be premature combustion or insufficient heat.Temperature - controlled preheating plug is used in many diesel engines. The preheating plug is equipped with a heating coil, which is actually composed of three coils - a block coil, an equalizing coil and a hot wire coil - in series. When the current passes through the preheating plug, the temperature of the hot wire ring located at the tip of the preheating plug rises first, making the preheating plug incandescent. As the resistance of the equalizing coil and arresting coil increases sharply with the temperature of the quench coil, the current flowing through the quench coil decreases. The preheating plug thus controls its own temperature. Some preheating plugs do not have equalization coils due to their temperature rise characteristics. The new type of temperature controlled preheating plug does not need a current sensor, which simplifies the preheating system. [2]Preheating plug monitor type preheating device Preheating plug monitor type preheating device consists of preheating plug, preheating plug monitor, preheating plug relay and other components. When the preheater plug heats up, the preheater plug monitor on the instrument panel will be displayed.The preheating plug monitor is installed on the instrument panel to monitor the heating process of the preheating plug. The preheater plug has a resistor connected to the same power supply. And when the preheater plug turns red, this resistor also turns red (normally, the preheater plug monitor should glow red for about 15 to 20 seconds after the circuit is switched on). Several preheat plug monitors are connected in parallel. Therefore, if a preheat plug is short-circuited, the preheat plug monitor will turn red earlier than normal. On the other hand, if a preheater plug is disconnected, it takes longer for the preheater plug monitor to turn red. Heating the preheater plug for longer than the specified time will damage the preheater plug monitor.The preheat plug relay prevents excessive current from passing through the starter switch and ensures that the preheat plug will not be affected by the voltage drop caused by the preheat plug monitor. The preheating plug relay actually consists of two relays: when the starter switch is in G(preheating) position, the current of one relay passes through the preheating plug monitor to the preheating plug; When the switch is in the START position, another relay sends current directly to the preheat plug without passing through the preheat plug monitor. This avoids the voltage drop due to the resistance of the preheating plug monitor during startup that would affect the preheating plug.
