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How Solenoids Make Automotive Doors More Secure

How Solenoids Make Automotive Compartments and Door Locks More Secure

Solenoids are used in the automotive industry to make effective locks and latches. The solenoid’s plunger connects to a latch that locks or unlocks when the system is activated with an electric current. The electromagnets are turned on and off through the supply and withdrawal of current. The electromagnet pulls the plunger in to unlatch, and when removed, a fail-safe spring re-engages the lock.

How Solenoid Automotive Locks Work

Solenoid automotive locks use remote controls to release tough doors by just pushing a button. The door lock can be monostable or bistable, depending on its use. Monostable designs allow the door to lock when there is no power supply automatically. In the less popular bistable system, the door locks when the solenoid is energized or supplied with power. The solenoid will need to be re-energized to unlock the door.

Automotive solenoids are available in two types, either Pull or Push configuration. Pull-type solenoids generate a pulling force on a large diameter plunger when energized. A small diameter shaft is attached to the bottom of the plunger to achieve a pushing motion inside the coil, thus creating a pushing motion out of the coil’s opposite side while the plunger is pulled in. Both types of solenoids are constructed in the same way, with the only difference being in the spring location and the plunger’s design.

Advantages of Autolock Solenoids

  • Excellent for releasing sticky latches with minimal noise
  • Safer than manual lock systems because they lock automatically when the remote is pressed.
  • Advanced design minimizes the size and weight of the device.
  • Consumes small amounts of energy; no power is utilized when the door is locked
  • Durable and shockproof
  • Fully scalable and can be designed in various sizes to fit different applications.

Why Solenoids Are Effective

The locking mechanism of the solenoid door lock is similar to a key lock system. The only difference is that the solenoid uses a low-voltage electrical energy supplier instead of a key. The power supply triggers the latch to pull into the door when a remote is pressed. The latch will hold the door in place as long as it is in the locked mode. These types of locks are used in remote-controlled and automated car locks.

Solenoid door locks use electromagnetic energy and an adjustable piston or plunger as the lock and key system. The system often has a low-voltage DC power source, such as a battery. When the control is triggered by way of a control device or remote, electric power flows to the coil activating the electromagnet.

The strong magnet pulls the piston unlocking the door. In most systems, the latch or locking mechanism is attached to the plunger through an actuator arm that pulls the lock out of position. When the power supply to the solenoid is cut off, the plunger resets the latch making the door lock again.

The locking solenoids are very robust and have been proven to withstand over 100,000 lock and unlock events. Some designs can handle many more locking and unlocking cycles. These systems are energy efficient, often requiring electric power for a maximum of one minute.

Energy Saving Option

Some solenoids’ designs help users save power by using a permanent magnet to maintain a locked or unlocked status when the lock system is idle. The permanent magnet holds the internal component of the solenoid in place by countering the internal spring force. This enables it to maintain a locked or unlocked state without consuming power.

Of course, the permanent magnet design requires a power supply to actuate the solenoid coil. Supplying the system with power reverses the solenoid coil’s polarity to counteract the permanent magnet’s hold. This allows the internal spring to push the piston to a position where it either inhibits or allows the locking mechanism’s movement.

Johnson Electric is a leading manufacturer of solenoids used in car manufacturing. Contact us for a consultation about your custom product development projects.


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