An Automatic Coffee Dispenser
An Automatic Coffee Dispenser
Client: Laura Vogtle, UAB Occupational Therapy
The present design was developed specifically to benefit Jodie, a young lady who is afflicted with cerebral palsy. She enjoys coffee and wished to have a device to help her pour her own cups of coffee throughout the day. Jodie is afflicted with the non-spastic variety of the disorder, and could potentially carry out many of the tasks associated with brewing coffee, provided suitable automated mechanisms were designed for her use. The primary objective of this design was to produce a device capable of providing Jodie with a means of dispensing coffee at a temperature between 105 and 125 degrees Fahrenheit. The coffee should be delivered into a drinking container that is spill resistant and compatible with a straw. In so doing, the coffee maker should satisfy the following conditions: 1) difficult to overturn (should withstand a force of 50 lbf to any surface that requires contact for operation), 2) actuation mechanisms that may be easily cycled by the client, 3) must fit into current residence with a minimum of disturbance to the current arrangement, 4) must have a positive placement device such that the drinking container is stable while coffee is being dispensed, and should require that at least 1 lbf be applied to the container to remove, 5) conforms to all applicable codes and standards.
The control system is divided into three major subsystems: 1) brew, 2) heat, and 3) dispense. The brew subsystem is the most complex, since the brew cycle consists of filling a tank with water, heating that water to the temp necessary to produce coffee and then returning to the off state so as to save power and increase safety. The heat subsystem is relatively straightforward. This system is placed on a timer in order that Jodie would not be required to actively return the device to an off state. Beyond the timing circuit this subsystem consists of an electrical resistance heater and a thermostat to regulate the output of the heater. The dispense system consists of a solenoid actuated ball valve. A relay has been placed in between the user-actuated switch and the valve to handle the relatively high current loads required by the solenoid. Throughout the electrical design of the device safety and ease of use were the utmost priorities. The device was designed to be actuated using only three switches. These switches are large push-button style and are easily managed by the client. The circuit design assures that the device would return to an off state after a set period of time without user intervention.
The cup is a 14-oz. model and the cup holder is constructed from 6061 T6 flatstock, which is easy to form and heat treat in the desired shape. An electrically controlled ball valve is the dispense valve. The exterior casing is fabricated from stainless steel, for looks and durability, as well as ease of bending. The final project is shown in Figure 4, and cost $1262.79