Easy Unplugger
Design Team
Drew Nathanson, Michael Notarangelo
Mario Peritore, Matthew Sauter
Design Advisor
Prof. Andrew Gouldstone
Sponsor
N/A
Abstract
This report describes the design process for a mechanical or electro-mechanical device to
allow remote unplugging of a cord from an electrical outlet. The primary motivation for
the project is the increased usage of portable electronics, and therefore the increased
number of times that device chargers or power cords are unplugged daily. Targeted users
include travelers, commuters, or users disabled to the extent that unplugging is difficult
or uncomfortable. From three initial mechanism ‘types’ (electronic, electro-mechanical,
mechanical), an electromechanical design was decided upon leading to the development
of more advanced and specific models. After choosing an electromechanical design, three
different electromechanical (E-M) designs were decided upon leading to the development
of more advanced and specific models. Three E-M designs were analyzed, using
mechanisms such as springs and motors, solenoids, and actuators to eject a plug. Testing
was done to determine the necessary force to remove a plug from an outlet, and to assess
how long this force persists. Experimental data resulted in the final selection, a locking
spring activated by a servomotor. This was modeled, constructed, tested, and analyzed
for production cost.
For more information, please contact a.gouldstone@neu.edu.
The Need for Project
The need for our research and
The increased use of portable electronics such as laptops, cell
proposed solution comes from phones and tablets has resulted in a drastic increase of plugging in and
the increased use of portable unplugging standard electronic cords. This is a simple task for most
electronics, resulting in an users under normal circumstances but for those users with physical
increase of plugging and limitations, who are in a rush, or even just to simplify their lives, a
unplugging electrical cords. device that could remotely release a plug would be of great benefit. The
This product makes that action target audience includes travelers, elderly and students who rely on
easier, quicker and safer for all electrical cords but do not want to reach down to unplug them every
users. time they change charging stations. This device would have to meet the
simple requirements of unplugging a cord from an outlet, be safe to
use, simple to operate, reduce the amount of energy required to unplug
and lastly not require user to physically approach the outlet. A product
that meets all of these requirements would benefit a large percentage of
the population allowing for proper unplugging techniques and
minimizing the chance of electrical shock or damaged wires.
The Design Project Objectives and Requirements
The objective of the design Design Objectives
was to create an
The design objectives of this project involved creating a
electromechanical adapter that device/method that would help alleviate the difficulty of unplugging an
would unplug an appliance appliance from a standard outlet. Goals were laid out that would help
remotely. accomplish the overall objective. These goals had to ensure that at the
conclusion of the project, the main design objective was satisfied. This
means the device would be simple to operate, primarily automated and
not require more energy than actually unplugging from the wall. The
design also had to not require the user to physically approach the outlet,
which would lead to the design being remotely triggered.
Design Requirements
The design requirements entailed quantitative data about the
metrics of the device. The final product would have to be small enough
to only take up one socket from a standard American outlet. It would
also have to successfully act as an adaptor meaning completing a circuit
between an appliance and the outlet. Lastly this device must be
comparable to many travel adaptors that are currently available and
cost around $19.99.
Design Concepts Considered
The proposed designs include mechanical and electromechanical
Five candidate design concepts
were developed, of which two mechanisms. The purely mechanical design was conceptualized by the
fully meet the requirements theory of bicycle brakes. The design would incorporate tension cables
and required additional that would move a lever to push the plug out of the outlet. The
planning and comparisons. electromechanical mechanism has the ability to be triggered remotely.
The mechanism can use many different actuation mechanisms to
unplug a plug. The actuation mechanisms that were investigated were a
spring, a small linear actuator and a power screw.
The preliminary designs were evaluated and the electromechanical
adaptor was found to be the best approach to solve this problem.
Factors that influenced this choice included the extended range of use
provided by the remote controlled system, the added safety of the
stationary prongs and finally the ease of resetting.
Additionally, to developing designs that would force the plug out
of the outlet, designs reducing the force it takes to unplug a plug from
an outlet were developed. Removing friction between two surfaces that
are being pulled or pushed reduces the required force to complete the
action. Therefore if a lubricant is applied to the prongs of a plug it
would require less force to unplug it from an outlet. However, applying
a lubricant to the prongs of a plug would be hazardous and unrealistic.
Research into this option has revealed studies in creating a mechanical
lubricant. Studies show that applying a vibration to a moving body that
is experiencing a normal force, reduces the force to move the body.
Changing the prong sizes was researched to see if it would reduce the
force to unplug a plug as well. Testing has revealed that in cases where
prong dimensions have been changed it considerably decreases force
required to unplug/plug into an outlet.
Recommended Design Concept
This design utilizes a simple (1)
spring to provide the force
Design Description
The final design that was decided on is an electromechanical
required for unplugging. adaptor that uses a spring and plunger to remove the plug from its
Simple motors activate strong outlet. When the plug is inserted into the outlet the plunger will travel
springs to minimize size. along a series of grooves, forcing itself to rotate and compress the
spring and eventually hitting a flat surface. This surface will act as a
hard stop, keeping the spring compressed and preventing the plunger
from immediately ejecting the plug. This groove system is crucial to
the design because without it and the flat stopping surface, the plug
would be immediately ejected. When the user wants to eject the plug, a
small servomotor connected to the plunger can then be activated using
an infrared signal causing the plunger to rotate, releasing it from its
hard stop. The spring will push the plunger along the grooves and eject
the plug from the wall. When the user inserts the plug into the wall
again for the next use, the spring will compress and the adapter will
reset.
(2)
Experimental Investigations
The first experiment that needed to be done was to determine the
force that must be overcome to unplug a plug from an outlet. To
accomplish this, a force gauge was used to remove different types of
plugs from both an outlet and power strip. Once the force was
determined, the spring necessary to overcome the force could be found.
One of the most important experiments that had to be completed was
determining the optimal spring to use in the adapter. To accomplish
this, a mock-up adapter was made using a 3D printer. This mock-up
had plungers with grooves to fit each spring being tested. There was no
hard stop system, so the plunger would attempt to eject the plug as soon
as it was released by the operator of the test. Using this test bed, two
springs were determined that would accomplish the goals of the test.
From here the final choice of spring was made.
(3)
Key Advantages of Recommended Concept
The main advantage of this concept is that the plug can be removed
remotely without the user having to walk over to the outlet. Existing
products that were researched required the user to move across the
room and unplug the cord at the socket. With the infrared transmitter,
the user needs to only push a button to eject their device from the wall.
Another key advantage is the cost of the adapter. Using a spring and
piston allows the cost to be kept to a minimum. Although using a
solenoid or linear actuator to push the plug out is possible, it is also
expensive. Also, having the plunger travel along the system of grooves
allows the adapter to reset itself every time the adapter is plugged in.
This saves the user from taking a separate step of resetting the adapter
before each use.
Financial Issues
The desired cost of $19.99 was
The product should be similarly priced to current electric travel
based on existing electrical adapters on the market. This means the price of the adaptor shall be
adaptors currently on the around $19.99. This brings up concerns with the design to ensure that it
market. does not use expensive parts. This means that the mechanism used in
the design shall be inexpensive. This is a challenge because many of
the mechanisms that were discussed had to be ruled out due to price.
However, despite the desired price the design cannot be cheaply
manufactured or contain poor quality parts, as it must accomplish the
goal.
Recommended Improvements
To maximize the efficiency
All prototypes created to date have utilized rapid prototyping to
and minimize the price the create quick, effective and strong models of the design. These models
final manufactured design shall were efficient for proof of concepts, product design and testing but will
be injection molded. eventually be abandoned before the product is moved to manufacturing.
To maximize cost and efficiency injection molding will be utilized for
all pieces. This form of manufacturing will create a cheap, strong and
precise set of parts to be assembled efficiently and cost effectively.