This paper is a group proposal of an Alexa integrated door closer. We argue its importance, talk about the technicalities of the device along with cost and manufacturing ideas. With the integration of a few key devices along with some custom-made parts the voice actuated door closed was born. Working in groups is what most engineering roles require of us, so this project gave me a good feel for how group work is.

Introduction
Throughout the last twenty years, numerous devices have been innovated for laziness.
One such example is the remote control. People do not have to stand up to change the channel,
but can instead do so from the comfort of their seat. The mobile phone was implemented to reach
a person far away. But, these inventions can be seen through a different lens; they allow us to
save time and money. For example, the remote channel permits us to change channels without
having to get up from our seats. Handheld smartphones enable us to see and hear loved ones on
video calls instead of having to travel far to meet up with them.

The hydraulic door closer is another device that has eased an aspect of life for us. It is a
device used to close the door automatically after a person enters a private business, store, or
agency. Not everyone cares about the door being closed or opened but the need for this device to
save energy if the place has an AC or heat. If the door is opened while the AC is working, it will
be a waste of energy that will change the entire temperature of the area and the AC is trying to
get it back for the desired temperature which is required more energy than usual or giving the
responsibility for someone else to close the door and it will be a waste of time that can be
invested in something else more valuable.

This device has made things easier for those entering or leaving stores while holding stuff
in their hands or carrying a huge product that they aren’t able to keep holding the door open.
Without the hydraulic door closer, a person would be needed to constantly hold the door open to
ensure all people would be able to smoothly enter and exit. Even in a house, a person who comes
back home from shopping holding many bags would benefit from this invention. Having a door
that is always closed and resisting mechanical force caused by the hydraulic piston attachment
would be difficult. The downside to this invention, however, is that when a door is opened, it
will be closed automatically and there is no control in terms of keeping the door open.
The solution we are proposing for this is to have a way of keeping the door open and
being able to close it without going through the hassle of closing it by yourself every time
someone pushes it open by generating a way of communicating with Alexa to give the order for
closing the door. The idea of communicating with Alexa is to keep the door closed and when
someone pushes the door open to get inside, the latch of the lock gets hung. When you want to
close the door all you have to do is to say “Alexa, close the door” and it will generate a current
on the solenoid to close the door by the tensioned torsion spring.

Technical Description
Many innovations have been proposed to solve the issue of the room door being left
open. For this proposal I will be discussing two different but inadequate innovations. First is the
hydraulic door closer. The next innovation is the torsion spring door closer. Shown below is a
picture of the hydraulic door closer.
Figure 1
Hydraulic Door Closer (McCoy)

The hydraulic door attaches to the top of the door and closes the door when it is open.
From this innovation an open door is always closed automatically. The consumer has no option
to leave the door open and loses the ability to do so unless someone or something is blocking the
door from closing. This is not ideal for a room situation since it is big and would look strange on
the inside of someone’s bedroom. Manual intervention is also necessary to keep the door open
which is one reason why this product is inferior to ours.
The torsion spring door closer also closes the door and it is very simple. Shown in Figure
2 is the torsion door closer. It has almost the same downsides as the hydraulic door closer, but is
much more compact and easy to install. Because of that fact, we decided to utilize something
similar in our design. The torsion spring door closer by itself deprives the consumer of control
which is what our product brings to the table. We are modernizing the door closer to integrate
systems like Alexa who can presently do things like turn on lights and even control electrical
outlets.
Figure 2
Torsion Spring Door Closer (Amazon)

To correct the shortcomings of the previously discussed topics we have integrated a door
closer with some electrical components to give the consumer more control. Our device consists
of a torsion spring door closer, a plunger solenoid, an Alexa smart plug, and a door stop each
designed for our particular application. I will talk about how these components each contribute
and work together to make something useful.
Our Alexa door closer will be sold as an Amazon Alexa accessory. Currently Alexa
accessories include smart bulbs, smart strip lights, and even smart speaker control for a sound
bar. We could introduce this product to expand the Alexa accessories list. The first component of
the product is the Alexa smart plug which goes into an outlet. When plugged in it turns blue and
is ready to pair with Alexa via WI-FI. One you pair the smart plug you can control if it lets
current through the outlet with your voice. If you say, “Alexa close the door”, current will flow
through the plug and the device will be activated. If you say, “Alexa stop”, then the flow of
current will halt or a timer can be set up so that the plug turns off after a few seconds. Shown in
Figure 3 is the Alexa smart plug.
Figure 3
Alexa Smart Plug. (Amazon)

The next component of the Alexa door closer is the torsion spring door closer which is
shown in Figure 2. This comes with a metal shaft which is used to tension the internal torsion
spring. When we twist the device and let it go, it will want to spin around opposite the direction
it was wound. Blocking it from spinning to the rest position is the door. The torsion spring door
closer is attached to the frame of the door and has a protruding shaft which rides on a plastic slot.
As the door is opened the spring is tensioned even more and when the door is released it closes
due to the tensioned spring.
The next component of the Alexa door closer is the door stop. This piece was designed in
Solid Works for display purposes. It is similar to modern door stops but it contains a slot which
is one part of how the door will stay open. Shown in Figure 4 is the door stop which attaches to
the bottom of the door. This piece works with the solenoid to keep the door open.

Figure 4
Slotted Door Stop. (Ryan)

The solenoid is a common electrical device which turns electrical energy into mechanical
energy. It is essentially just a loop of wire and to concentrate the magnetic field engineers
sometimes wrap it around a ferrous material. When alternating current runs through the wire a
changing magnetic field is produced which is a corollary to Faraday’s Law of Electromagnetic
Induction. Due to the shape of the wire (it is wound in a helix-like shape) the magnetic field
produced is equivalent to that of a bar magnet. If such a field is produced as we introduce a
plunger or “armature” to the solenoid then what is produced is a plunger type solenoid also
known as a latching solenoid. When the solenoid has current running through it any ferrous
material will want to align with the magnetic field lines and will be retracted to the center of the
coil. A spring mechanism is typically used so that when the current is disabled, the plunger
returns to the rest position ready to repeat the process. Shown below are the extended and
retracted positions of a sectioned latching solenoid.

Figure 5
Plunger Type Solenoid (Passive Components Blog)

When these devices work together the consumer achieves control and conform. From
their desk, they can close the latched door while continuing their task. They have the option to
leave the door open or close using voice control. Shown below is a picture of all the components
assembled together.

Figure 6
Alexa Door Closer Assembly (Ryan)

Process of Innovation: Torsion Door Closer (Aiza)
A torsion door closer is one of the major components to our invention and is, essentially,
a pre-existing invention we have chosen to alter. It converts doors with hinges to be self-closing,
which eases the process for many people who don’t wish to manually exert pressure to force a
door closed. The main part of the torsion door closer is manufactured by a process called casting,
in which a non-porous material, such as cast iron or aluminium alloy, is used to precisely mold
the shape of the object. This process could take approximately 5-16 weeks, depending on the
quantity being casted. In terms of price, aluminium casting tends to be less expensive than other
options. It’s a fairly inexpensive material but produces adequate thermal and electrical
conductivity. The use of aluminium alloys can reduce the need for finishing treatments and
decrease overall cost. Iron/metal casting is a common casting process, but tends to be more
expensive due to durability and stability. The torsion door closer model we have selected to alter
is manufactured by aluminum casting.

The torsion spring is a critical component of this door closer and is considered to be its
power source. Torsion springs are composed of steel and should be a designated length and
strength to ensure they work as desired. They are twisted from one end to store and release
rotational energy to the other end. Instead of a typical push-pull function, torsion springs operate
with a twisting force. Screws are another component of this invention and are used to cover open
areas and provide additional support. These are also manufactured by casting using either iron,
steel, or brass.

This spring door closer can be used on doors up to 150 pounds and is ideal for bedroom
doors. These work on both left and right-handed doors and can easily be adjusted to add or
reduce tension as required. Lithium grease lubricant can be used to ensure the door’s
functionality. This results in a smooth door closing and speed can be adjusted by altering the
tension.

Additional components for this invention include a closing arm and a slide plate that is
placed under the arm. The slide plate is screwed onto the door and is connected to the closing
arm so that when the door is opened, it will close afterwards.

Schematics of Proposed Parts
Figure 7

Slotted Door Stop Drawing

Figure 8
Torsion Spring Door Closer Drawing (Amazon)

Process of Innovation: Latching Solenoid (Eric)
Next, we will discuss another component that will be used for our innovation, this
component is a latching solenoid. A latching solenoid is an electromagnetic device that maintains
a predetermined position without constant application of power by using an electrical current
pulse or internal permanent magnets that are installed around the bottom of the coil core (The
Basics of Latching Solenoids). The power to the coil is cut off once the magnetic field generated
by the powered solenoid coil has drawn the plunger into the coil center. This would normally
cause the plunger to release, but in the case of a latching solenoid, the magnets maintain the
solenoid operational with no current drain from the power supply. When the solenoid must be
deactivated, a pulse of current, in the opposite direction, is applied which repels the actuation
current of the plunger, deactivating the solenoid. (Scott, what is a latching solenoid?). Permanent
magnets are built into the Latching Solenoid’s structure in such a way that they move flux
throughout the magnetic circuit when the device is deenergized, generating force without any
externally applied stimulation (What is a latching solenoid? general technical information 2021).
A visual of the item generating flux and where its being directed can be shown below:

Figure 9
Flux generated from magnets in Latching solenoid (GeePlus)

The specs of the latching solenoid include the plunger, the permanent magnet, the coil,
and the spring. The plunger is the part of the solenoid that moves and transfers linear motion
from the solenoid it was meant to control. This occurs because when the device is activated, the
electromagnetic field formed in the solenoid coil pocket pulls the plunger into the pocket,
providing linear motion (Scott, What is a solenoid plunger? 2021). The permanent magnets, as
mentioned previously, are used to hold a predetermined position without the application of an
electrical current on a continuous basis. It works in connection with the coil, because when a
current is given to the coil it gives a small magnetic flux to the permanent magnets which affects
the plunger, making it move to a fixed pole (The basics of Latching Solenoids). Lastly, the spring
allows the plunger to stay in an extended or retraction position, whichever is needed (Latching
solenoid theory). Finally, because the magnetic latching solenoid uses way less power compared
to other counterparts it makes them environmentally sound reducing its cost. The price of this
latching solenoid can range between 20$-130$.

Figure 10
Latched position and de-latched position of solenoid (Global Spec)

References
Amazon Smart Plug, Works with Alexa – A Certified for Humans Device. Amazon.
https://www.amazon.com/Amazon-smart-plug-works-with-Alexa/dp/B089DR29T6.

The Basics of Latching Solenoids. (2014). TLX Technologies.
https://www.tlxtech.com/articles/latching-solenoid-basics

Components Used in Door Closer. (2013). Everest.
http://www.everestdoorclosers.com/componets.htm

Cost of Casting Aluminum vs. Bronze. (2020, December 1). Redstone Manufacturing.
https://redstonemanufacturing.com/cost-of-casting-aluminum-vs-bronze/

Latching Solenoid Theory. (2014). TLX Technologies.
https://www.tlxtech.com/solenoid-theory/latching-solenoid-theory

McCoy. (2021). Hydraulic vs pneumatic door closer. McCoy Mart.
https://mccoymart.com/post/hydraulic-vs-pneumatic-door-closer/.

Prime-Line KC60HD Safety Spring Door Closer. Amazon.
Prime-Line KC60HD Safety Spring Door Closer – Easy to Install to Convert Hinged
Doors to Self-Closing – Diecast Construction (4-1/4” Satin Chrome, Non-Handed) – –
Amazon.com

Scott, P. (2021). What is a Latching Solenoid?
https://www.wise-geek.com/what-is-a-latching-solenoid.htm.

Scott, P. (2021). What is a Solenoid Plunger?
What Is a Solenoid Plunger? (with pictures) (infobloom.com)

Solenoids, contactors and electromechanical relays explained. Passive Components Blog. (2020,
August 14). Retrieved November 23, 2021, from https://passive-components.eu/solenoidscontactors-and-electromechanical-relays-explained/

Torsion Springs Specifications. Global Spec.
Torsion Springs Specifications | Engineering360 (globalspec.com)

What is a Latching Solenoid? General Technical Paper. (2013). Everest.
http://www.everestdoorclosers.com/componets.htm

What is a Torsion Spring? (2021). WB Jones.
https://www.springsfast.com/resources/blog/what-is-a-torsion-spring/
What is the Purpose of a Door Closer? Ambassador Locksmiths.
What Is The Purpose Of A Door Closer? – Ambassador Locksmith