How Starter Motors Work
Summary
TLDRThis video explains the detailed process of how a car's starter motor system works. It describes how turning the ignition key sends a small electric current to the solenoid coil, activating both the pulling and holding coils to create a magnetic field. This field moves a piston, engaging the pinion gear with the flywheel, allowing the engine to start. Once the engine runs faster than the starter motor, the system disengages. The video also covers how the car battery recharges. Viewers are encouraged to check out related videos for more insights on automotive engineering.
Takeaways
- 🔑 Turning the ignition key sends a small electric current to the solenoid coil.
- 🔋 The solenoid is made up of two coils: the pulling coil and the holding coil.
- 🔌 The holding coil is connected to the starter motor casing, returning current to the battery via the car's frame.
- ⚡ Both coils are energized, creating a magnetic field that pulls the piston back, allowing the contactor plate to connect across the main terminals.
- 🚫 The pulling coil turns off once both ends become the same voltage, as no current flows through it.
- 📉 The holding coil continues running since it requires less energy to hold the piston in position.
- 🛠️ As the piston moves, it pulls a lever that rotates the pinion, locking it into the flywheel to start the engine.
- 🔄 The rotor spins rapidly due to the electromagnetic field produced by the coil, creating torque that turns the flywheel.
- 🌀 When the engine begins rotating faster than the starter motor, the overrunning clutch unlocks, allowing the pinion gear to spin freely.
- 🔋 Releasing the key cuts power to the solenoid, disengaging the pinion gear, while the alternator recharges the battery as the engine runs on its own.
Q & A
What happens when the ignition key is turned?
-When the ignition key is turned, a small current of electricity flows into the solenoid coil, which activates both the pulling and holding coils, creating a strong magnetic field.
What are the functions of the pulling coil and the holding coil?
-The pulling coil is responsible for pulling the piston back by creating a strong magnetic field, while the holding coil maintains the piston in position with far less energy after the pulling coil turns off.
How does the pulling coil turn off?
-The pulling coil turns off when both ends of the coil reach the same voltage, causing no voltage difference across it, so no current flows through the pulling coil.
What happens after the piston moves back?
-As the piston moves back, it pulls on a lever, which pivots and transfers motion to the drive sleeve. This pushes the pinion forward, slightly rotating it to lock the rollers in the clutch and slide the pinion into the flywheel.
What role does the contactor plate play?
-The contactor plate connects across the main terminals, allowing a large current to flow through it and into the starter motor, powering the motor to turn the flywheel.
How does the current flow through the starter motor?
-The current flows through the contactor plate, through the thick wire to the brushes, then to the commutator plates, through the coil, and back through another commutator plate and brush, which is grounded to the car's frame.
How does the rotor or armature rotate?
-The rotor rotates by the interaction between the electromagnetic field generated by the starter motor coil and the permanent magnet or field winding in the stator. This causes the rotor to rotate with high speed and torque.
What happens when the flywheel starts the combustion process?
-Once the flywheel starts the combustion process, the engine rotates the flywheel faster than the starter motor, unlocking the overrunning clutch so the pinion gear can spin freely.
What happens when the key is released after starting the engine?
-When the key is released, the power to the solenoid coil is cut off, releasing the piston. A spring pushes the lever back, removing the pinion gear from the flywheel, and the starter motor stops running.
How does the battery recharge after the engine starts?
-Once the engine is running, the alternator takes over and recharges the battery, allowing the combustion engine to continue running by itself.
Outlines
🔑 How the Ignition Key Powers the Starter Motor
When the ignition key is turned, a small electric current flows into the solenoid coil, which consists of two coils: the pulling coil and the holding coil. The holding coil connects to the starter motor casing, allowing current to return to the battery via the car’s frame. The pulling coil is connected to the main output terminal, and both coils generate a magnetic field to move the piston. As the contactor plate connects the main terminals, the pulling coil deactivates, while the holding coil continues to run with less energy to maintain the piston’s position. The piston movement pulls a lever, transferring motion to the drive sleeve, which pushes and slightly rotates the pinion to lock the clutch rollers and slide the pinion into the flywheel.
⚡ The Starter Motor Engages and Powers the Engine
Once the contactor plate connects the terminals, the pulling coil turns off, allowing a large current to flow through the contactor plate, thick wire, and into the brushes. This current moves through the commutator plates, the coil, and back through another commutator plate, grounding it to the car’s frame and returning it to the battery. The coil generates an electromagnetic field that interacts with the permanent magnet or stator windings. This interaction causes the rotor to rotate quickly and with high torque, transferring power through the shaft and clutch to the pinion gear, which turns the flywheel to initiate the engine's combustion process.
🔁 Overrunning Clutch Disengages as Engine Takes Over
As the flywheel starts the engine’s combustion process, the engine eventually rotates the flywheel faster than the starter motor, unlocking the overrunning clutch. This allows the pinion gear to spin freely. When the key is released, power to the solenoid coil is cut, releasing the piston, and a spring pushes the lever back, disengaging the pinion gear from the flywheel. The current to the starter motor is cut off, and the engine continues to run independently. Meanwhile, the alternator recharges the car battery.
🔗 Learn More About Car Batteries and Stay Connected
This video concludes with a reference to a previous video covering how car batteries work, providing a link for viewers to explore further. The narrator encourages viewers to check out additional videos on automotive engineering and stay connected through social media platforms such as Facebook, Twitter, Instagram, TikTok, LinkedIn, and their website, theengineeringmindset.com.
Mindmap
Keywords
💡Solenoid
💡Pulling Coil
💡Holding Coil
💡Contactor Plate
💡Pinion Gear
💡Flywheel
💡Overrunning Clutch
💡Commutator
💡Rotor
💡Alternator
Highlights
The ignition key triggers a small current of electricity to flow into the solenoid coil, initiating the start process.
The solenoid consists of two coils: the pulling coil and the holding coil, both of which create a strong magnetic field.
The pulling coil connects to the main output terminal, while the holding coil is grounded through the car’s frame.
When both coils are energized, the piston is pulled back, connecting the contactor plate across the main terminals.
Once the contactor plate connects, the pulling coil turns off as no current flows through it due to equal voltage.
The holding coil uses less energy to maintain the piston’s position, continuing to operate while the pulling coil turns off.
The piston movement pulls a lever, which pivots and pushes the drive sleeve forward, slightly rotating the pinion.
The pinion locks with the rollers in the clutch, sliding into the flywheel to initiate engine rotation.
A large current flows through the contactor plate and the thick wire into the starter motor's brushes and commutator plates.
The rotor of the starter motor rotates rapidly due to electromagnetic interaction between the coil and permanent magnet.
The rotating rotor transfers motion through the clutch and pinion gear, turning the flywheel to start the combustion process.
As the engine surpasses the starter motor speed, the overrunning clutch unlocks, allowing the pinion gear to spin freely.
When the ignition key is released, power to the solenoid coil is cut, releasing the piston and retracting the pinion gear from the flywheel.
The starter motor stops, and the combustion engine runs independently, while the alternator recharges the battery.
Detailed explanation of how the car battery works, previously covered in another video.
Transcripts
when the ignition key is turned it
causes a small current of electricity to
flow into the solenoid coil the solenoid
is usually made of two coils known as
the pulling coil and the holding coil
the end of the holding coil connects to
the casing of the starter motor so the
current returns to the battery via the
frame of the car the pulling coil is
connected to the main output terminal
both coils are energized to create a
strong magnetic field this pulls the
Piston back and as the contactor plate
connects across the main terminals both
ends of the pulling coil will become the
same voltage there will be no voltage
difference across this coil at that
point in time so the coil will turn off
because there's no current flowing
through it it takes far less energy to
hold the piston in position so the hold
in coil continues to run as the Piston
moves back is going to pull on the lever
this pivots and transfers the motion to
the drive sleeve pushing it forwards as
it moves forwards it slightly rotates
the pinion allowing it to lock the
rollers in the clutch and Slide the
pinion into the flywheel as the
contactor plate connects across the
terminals and turns the Pullin coil off
a very large current will now flow
through the contactor plate through the
thick wire and into the brushes from
here it flows to the commutator plates
and through the coil then back to
another commutator plate and through
another brush which is grounded to the
frame of the car so the current returns
to the battery the coil produces an
electromagnetic field which interacts
with the permanent magnet or field
winding in the stator this interaction
causes the rotor or amateur to rotate
very fast and with a high torque the
rotor transfers this through the shaft
through the clutch and into the pinion
gear which turns the flywheel as the
flywheel starts the combustion process
the engine will eventually begin to
rotate the flywheel faster than the
starter motor this unlocks the
overrunning clutch so the pinion gear
spins freely when the key is released it
cuts the power to the solenoid coil
which releases the Piston the spring
pushes the lever back removing the
pinion gear from the flywheel the
current is cut to the starter motor the
combustion engine continues to run by
itself and the alternator recharges the
battery we have also covered how the car
battery works in detail previously I'll
leave a link for you in the video
description down below check out these
videos to continue learning about
automotive engineering and I'll catch
you there for the next lesson don't
forget to follow us on Facebook Twitter
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engineering mindset.com
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