1. Definition and working principle of automobile starting system
To make the engine transition from the static state to the working state, the crankshaft of the engine must be turned by external force to make the piston reciprocate. The combustible gas mixture in the cylinder combusts and expands to work, pushing the piston down to rotate the crankshaft. Only the engine can run on its own, and the working cycle can be carried out automatically. Therefore, the whole process of the crankshaft starting to rotate under the action of the external force until the engine starts to automatically run at idle speed is called the start of the engine. The device required to complete the starting process is called the engine’s starting system.
1. Function: to start a stationary engine. 2. Composition: composed of starter and accessory device.
The starter system is a starter, which is equipped with a small high-speed motor that drives a gear to start a stationary engine and turn it into self-operation. It includes a starter, a starting relay and an anti-theft system.
The automobile starting system is mainly composed of a starter and a start control circuit
The starter is used to start the engine. It is mainly composed of three parts: the motor part, the transmission mechanism (or meshing mechanism) and the start switch.
1. Engine starting principle To make the engine transition from the static state to the working state, the crankshaft of the engine must be turned with external force to inhale (or form) a combustible mixture in the cylinder and burn and expand, the working cycle can be automatically carried out. The whole process that the crankshaft starts to rotate under the action of external force until the engine starts to idle automatically is called the engine start. There are many ways to start the engine. The motor commonly used in automobile engines starts with the motor as mechanical power. When the gear on the motor shaft is meshed with the ring gear on the periphery of the flywheel of the engine, the power is transmitted to the flywheel and the crankshaft to rotate it. The motor itself uses the battery as an energy source. At present, most automobile engines are started by electric motors.
2. Starter composition The starter is generally composed of three parts: (1) DC series motor, its role is to generate torque. (2) Transmission mechanism (or meshing mechanism), its function is: when the engine is started, the starter drive gear is engaged with the flywheel ring, and the starter torque is transmitted to the engine crankshaft; and after the engine is started. The drive gear slips and the flywheel gear ring is automatically disengaged. (3) Control device (ie switch). Used to connect and cut off the circuit between the starter and the battery. In some cars, it also has the function of connecting and removing the additional resistance of the ignition coil.
3. The function of the starter The function of the starter is: use the starter to convert the electrical energy of the battery into mechanical energy, and then drag the engine to start through the transmission mechanism.
4. Classification of starters In the three components of various starters, there is generally no essential difference in the motor part, and the control method and the engagement method of the transmission mechanism are very different. Therefore, the starter is based on the control method and The transmission mechanism is classified according to the different ways of engagement.
5. According to different control methods, the starter can be divided into: (1) Mechanical control type (2) Electromagnetic control type According to the drive mechanism engagement method, the starter can be divided into: a. Inertial meshing type b. Forced meshing type c . Armature mobile d. Gear mobile e. Coaxial starter type. In addition to the above, there are permanent magnet starters with permanent magnets for magnetic poles, and deceleration starters with built-in reduction gears. The model of the starter is: (1) QDJ stands for decelerating starter; QDY stands for permanent magnet starter (including permanent magnet decelerating starter), and J and Y indicate “minus” and “yong” respectively. (2) Voltage level: 1-12V; 2-24V (3) Power level (4) Modification code (5) Design serial number
Automotive starter control device includes electromagnetic switch, starter relay and ignition starter switch, etc., the electromagnetic switch is made together with the starter.
1. Electromagnetic switch 1. Structural characteristics of electromagnetic switch: Electromagnetic switch is mainly composed of electromagnet mechanism and motor switch. The electromagnet mechanism is composed of fixed iron core, movable iron core, suction coil and holding coil. The fixed iron core is fixed, and the movable iron core can be moved axially in the copper sleeve. A push rod is fixed at the front end of the movable iron core, and a switch contact plate is installed at the front end of the push rod. A reset spring is installed on the outside of the copper sleeve, and its function is to reset the movable iron core and other movable parts. The arrangement of the terminals of the electromagnetic switch wiring is shown 2. Working principle of the electromagnetic switch: When the magnetic flux generated by the suction coil and the holding coil is energized in the same direction, the electromagnetic suction forces are superimposed on each other, which can attract the movable iron core to move forward until the front end of the push rod touches The disk connects the electric switch contact to the potential motor main circuit. When the direction of the magnetic pain caused by the energization of the suction coil and the holding coil is opposite, the electromagnetic suction forces cancel each other. Under the action of the reset spring, the movable iron core and other movable parts are automatically reset, the contact plate and the contact are disconnected, and the motor main circuit is disconnected. .
Second, the starting relay The schematic diagram of the starting relay is shown in the upper left part, which is composed of the electromagnet mechanism and the contact assembly. The coils are respectively connected to the ignition switch terminal and the ground terminal “E” on the housing, the fixed contact is connected to the starter terminal “S”, and the movable contact is connected to the battery terminal “BAT” via the contact arm and the bracket. The starting relay electric shock is a normally open contact. When the coil is energized, the relay core generates electromagnetic force to close the contact, thereby connecting the circuit of the suction coil and the holding coil controlled by the relay.
3. Dongfeng EQ1090 car starting circuit Dongfeng EQ1090 car uses QD124 starter. It is electromagnetically controlled strong mesh starter. It adopts rolling one-way clutch, drive gear is 11 teeth, rated power is 1.5kw. The circuit as shown includes the control circuit and the starter main circuit. 1. Control circuit The control circuit includes a starter relay control circuit and a starter electromagnetic switch control circuit. The starting relay control circuit is controlled by the ignition switch, and the controlled object is the relay coil circuit. When the ignition switch start gear is turned on, the current flows from the battery politics through the starter power terminal to the ammeter. After passing the ignition switch from the ammeter, the relay coil returns to the negative pole of the battery. Therefore, the relay core generates a strong electromagnetic attraction, which is when the relay contacts are closed and the control circuit of the electromagnetic switch of the starter is connected. 2. The main circuit is: battery positive pole → starter power terminal → electromagnetic switch → excitation winding resistance → armature winding resistance → grounding → battery negative pole, so the starter generates electromagnetic torque and starts the engine.
three. Engine starting method
(1) Engine start? The engine needs to rotate the crankshaft with external force until the flammable mixture can be formed in the cylinder and burned on fire before it can automatically perform the working cycle and turn into the working state. (2) Starting process? The engine changes from static to working state The whole process (3) Starting time? The time from starting to self-running, electric start <5s, interval 15s, manual start <30s. (4) Starting speed? When starting under certain environmental conditions, the minimum speed necessary is 100~300r/min for diesel engine and 50~70r/min for gasoline engine. (5) Starting method: human start: turn the flywheel by hand, use small power machine? Electric start: battery as power source, series excited DC motor? Gasoline engine for diesel engine start: used for high power diesel engine start? Compressed air start: high pressure Air is sent into the cylinder to push the piston according to the working order to drive the crankshaft to rotate