Oven Door Opener
The client has quite weak hands and arms, and found it virtually impossible to open the oven door; she always needed the help of her husband.
Like most oven doors there is an initial force that must be overcome to open the door. Once this point is reached the force to continue opening the door is considerably lower.
This device enables the client to use the oven whenever she wishes.
The Challenge
The client wanted to be able to use the oven without the help of her husband. Because of the large, initial force needed to open the oven door, and the client’s arm and hand weakness, it was impossible for her to open the door.
No suitable commercial solutions exist and because of the physical constraints within the kitchen, a “mechanical lever” solution was not feasible from a both a safety point of view and the practicality of housing a large lever.
The solution
On examination of the kitchen layout and specifically the oven door, a concept for the solution was agreed with the client.
This was to be an electric motor, located at the rear of the worktop that on demand would move a pushrod. This would in turn engage with a bracket, fixed to the oven door, using a convenient screw in the side of the door. This would then open the door just a few centimetres, getting over the initial high force. Once the door is at this point the client would be able to open the door with ease.
Closing would a reversal of the same procedure. The door would be closed against the pushrod and then the electric motor reversed to allow the door to close under it own return string.
Measurements of the force required to open the oven door were made using luggage scales. This was estimated to be around 7kg. This figure enabled the motor torque to be estimated and a suitable electric motor to be sourced.
All the parts were mounted on a “chassis” consisting of an aluminium strip just 2mm thick x 25mm wide. All the forces required would be in tension, from the edge of the worktop, so the support structure could be quite small and neat.
Most of the structure was 3D printed. Parts requiring higher strength were printed at a higher density.
The whole system was controlled by a single, large push button at the worktop edge. Each press is detected by the software embedded in an ATtiny85 (miniature Arduino type single board processor). This starts the motor running, moving the pushrod out. This runs until a limit switch is reached. Pressing the button again retracts the pushrod. If left extended for more than 2 minutes, the pushrod is retracted automatically. This reduces the chance of the user “catching” themselves on the pushrod end. This time was agreed with the client, but could easily be changed within the programming of the processor.
The benefit
The device has had a significant impact on the client’s life. This is part of an email received from the client:
“Thank you so much; the device has already made a significant difference and I was able to heat up my lunch yesterday whilst my husband was out and I am able to help with the cooking which I was not able to do before. Everything all working to plan. Thank you again.”
- Skills involved:
- Issues Addresses:
- Activities Helped:
- Location:
- Solution:
