Porsche Title

As we are trying to get the Porsche street registered again, we were able to acquire the Title in the name of MIT and we can begin moving forward with registration and inspection. This also means that any injury related to the vehicle is now in MIT's name, which is much better than in a single person's name.

Now on the To-Do list is to retrofit the windshield washer system from the original configuration, which utilized the air pressure from the spare tire, to a modern-electric motor driven system. Parts are on the bench as we type.

Porsche Signals

The other weekend, we started working through some issues we were having with the signal lights on the Porsche. We were having issues where the individual signals would only turn on when the stalk was moved in a direction, and the hazards would flash once or twice and then stop responding.

Low voltage electrical relays. Picture taken from driver's seat.

As we delved deeper into the vehicle, we remembered that the vehicle is 38 years old and even though it came to us in good condition, it is hard to stop the aging of the electrical terminals.

Note the coloring of the contacts.

The signal/hazard relay is the square box located on the bottom of the picture. We thought our signal issue was an issue with the signal relay, and we found a replacement online. It should be a plug and play type of situation. Right out of the box, we noticed that the original was significantly heavier in weight, and about 80% of the size of the original.

Original on left, replacement on right.

The replacement relay physically fit quite well, and we powered up the low voltage to test out the system. Interestingly, the signals would flash very slowly (~2 seconds on, ~2 seconds off). The hazards also had a different frequency. While this might satisfy the Massachusetts state inspection, we were concerned that it wasn't fast enough to catch another vehicle operator's eye.

After scratching our heads for quite a while, we remembered that the signal lights were replaced with LED lights a few years back. LEDs (Light Emitting Diodes) consume much less power, and are great for a variety of applications. About the only environment that has had some difficulty adapting to LEDs is the traffic light and runway light environments. Since LEDs produce so much less heat than conventional lighting sources, ice can build up on these surfaces and either block the light or change the light refracting properties of the lens such that the effectiveness of the lights are diminshed.

For us however, if we applied the RC Circuit concept to the system, the change in the headlight source may have been changing the dynamics for which the relay was designed to switch with. Thus, we switched back to the original relay and used the opportunity to take a look inside.

The relay is simple in concept, relying on the magnetic field created by an applied voltage to close another set of contacts and close the circuit. A solid state relay is traditionally viewed as being more energy efficient since it does not require the currents needed to hold the contact closed. For reference, efficiency is the output per unit of input. Since the mechanical relay (as shown above) used some energy and arguable produces no work (output), it is seen as a negative efficiency influence. Solid state relays have some pitfalls when used for certain applications though. Feel free to contact us and I should be able to elaborate on this in some detail.

Using a lab bench, the relay worked perfectly fine. However, we noticed it was hard to get a good connection through the 38 years of age. We never considered this as a potential problem being that the contacts should not have moved within the housing, therefore the connection should never have been broken. We were wrong.

Using microgrit sandpaper (CAMI-600 in this case), we sanded down the male ends of the connectors and reinserted the original relay. Everything worked fine, the timing of the hazards/signals were within the expected range (~0.75 sec on/~0.75 sec off), and both the hazards and signals had the same frequency.

For us, this was surely a learning experience in that we shouldn't make assumptions without some verification, and that we should always check our contacts before changing parts.

IAP Week 4 - To the streets

Street day for EVT!

We got the trike a flag!

helmets, safety vests and bike tools

roberto as the first pilot

lauren on the trike

In all, it was a pretty successful first day on the streets. Not all our instrumentation is set up so we don't have an accurate speed read out but we estimate the top speed was around 17-20mph.

IAP Week 3 - maiden crawl

Another extremely productive week at EVT.

Sprocket got machined! Here are some action shots!

the joys of cnc machining

done!

hub fits!

After the sprocket got machined we did a couple of tests with the wheel propped up.

Then it was time to get to the hallway!

woops

IAP Week 2 - Lots of building!

IAP Week 2 is over and we are on schedule to be able to make a maiden crawl by next Saturday. This week lots of milling, turning, broaching, drilling, deburring, crimping, tapping, brushing, sanding occurred and we are very proud with the results!

waterjetting the alumnium (thanks Javi!)

Broaching the key on the sprocket

sprocket has been keyed!

fitting the bulkhead connectors

looks like the parts fit! time to sand and clean them!

yay! motor fits!

eric and joey making connectors

data connector layout

getting ready to rivet the angle stock to the waterjet plate

erich lining up both pieces carefully

the riveting art of riveting

notice our temporary acrylic sprocket (steel coming soon)

ready to assemble! 

putting in the new stays

looking pretty thus far! (notice the sexy bulkhead connector)

getting the motor in place!

"fully" assembled!! shorter u-bolts and steel sprocket coming soon!

1

starboard side of the trike

rear of the trike!

everyone tweaking the mounts

a video of the motor turning! (tension needs to be adjusted)

jacob on the trike!

woohoo the brake firmware/motor control works! thanks EE team!

in order to get familiar with HSMworks on the EZ track Jacob and Roberto machined a piece of abs with same features that are going to be machined on the steel sprocket this coming week (thanks to Andrew Carlson for the help!)

IAP 2014 Week 1

IAP is a very busy time for us! Lots of design, machining and electronics going on these past couple of days as we ramp up to be able to drive the trike around the block by the end of the month!

Following are a couple of photos of the progress made by mechanical sub-teams, in another post the EE dudes will be posting their advances as well! lots of CAD advances this week, we plan to waterjet the plates this week!

sexy EVT chainguard and nice hollowed out sprocket

note how the data and the power connectors mount on the aluminum

Hollowed out sprocket under max chain load. Stresses are reasonable.

lauren busy machining

finished sprocket adaptor

sprocket adapter  mounted!

ubolts for the base done!

2nd Laser Cut Drive Assembly

Happy Holidays and happy new years to everyone!

We have fabricated a new laser-cut prototype with more details. Next up is the waterjetted final assembly.

The structural support for the motor is comprised of three plates which we
named "Base", "Shark Fin", and "Rear Fork".  As shown in the photo, we
laser-cut new plywood prototypes of all three.  The seat is supported with
aluminum angle, which might be the actual pieces that we use in the final
build.  The actual LMC-170 motor had indeed arrived and was relocated
slightly in the new Shark Fin plate, so it is now well clear of any
interference.  The Base plate still needs to be remade to solve U-bolt
alignment and clearance issues.

We have received the LMC-170 motor and intend to install it during IAP.

second laser cut prototype