Wednesday, July 22, 2009
Friday, July 17, 2009
Today, we started dismantling the car at 9am. We finished removing the engine at 3am and were out of the shop at 3:30am. We completed all of the major dismantling in only one day. We took out the gas tank, the battery pack, the engine, and parts of the interior. Take a look at our blog to see a time lapse of the whole day! It is an awesome video!
Sunday July 12th: Final dismantling:
In the morning, I finished removing the rest of the things from the engine compartment and I rebolted the suspension in place so the car can roll. The car is pretty much entirely ready to have new parts installed in it.
Drive Train Revision:
Radu and I had a long talk in the morning about the drive train. The original plan was to put the motor in the exhaust channel under the car and then run a shaft up to the differential. This plan had a couple of serious drawbacks: first, we would have to invert the rear differential which could lead to lubrication problems; second, we would have to cut into the exhaust channel and do body work which is in general a pretty bad idea; third, we would be spinning the differential at 12,000 rpm when the car is going 100mph. After thinking about all these challenges, I thought up another way that we could do the drive train which will probably be a lot easier. My idea is to mount the motor above the differential and have a chain drive linking the two. The chain drive will give us a lot of flexibility with the gearing and the whole assembly will just sit where the old engine was. This plan solves all of the major drawbacks of the old plan but introduces a few new challenges. Mainly, the chain drive and all the mounting. Radu and I both really like the idea and we talked to the rest of the team about it and they also think it is a good idea. I made a CAD model of the whole motor/differential assembly in the evening and I plan to talk it over with the other guys tomorrow.
Monday July 13th:
Mike, Radu, Matt, and I had a long design powwow in the morning about the motor/differential mount. We decided that the best way to do the drive train is to rigidly mount the differential to the motor and then mount both of those to the car through the existing motor mounts and several anti-roll bars. Here is a picture of the CAD model that we finally settled on.
Tuesday July 14th: Motor Frame:
Today I assembled all the basic components of the frame and tack-welded them together. Cutting the compound angles on the cold-cut saw was a little bit of a challenge but Mike had a good suggestion to make angle blocks and it worked very well.
I spent several hours calling junk-yards and BMW shops in the area to find a differential that we can use. The Ford 9 inch differential that we have and were planning to use before is too big to fit in the car so we decided to look for another, smaller differential. Because our motor will be outputting so much power, we want a very strong differential so we decided on a BMW rear differential. We would like to get a Limited Slip Differential to improve our handling but it is not critical. I ended up finding a good used transmission at Nissenbaum’s auto salvage very close to the shop. I went over there and picked it up in the afternoon. The guys at Nissenbaum’s were very helpful and were very interested in our project.
Wednesday July 15th: Motor Frame:
Mike and I went in the morning and water-jet cut the front face of the motor mount. It took about 25 minutes worth of cutting time because the steel was 1/2” thick. I welded the entire frame together and fitted the motor and differential into it. The frame itself weighs about 50-60 lbs. With the motor and differential, the frame weighs about 400 pounds.
Thursday July 16th: Differential:
I degreased and repainted the Differential so it is protected and looks good. I sized, lined up, and drilled the hole to mount the differential to the front plate of the motor frame as well as the hole where the shaft goes through the front plate of the frame.
Motor & Differential Frame:
I finished welding the pieces that Matt made for the engine mount cross bar. The steel frame is mostly done. All that is left is to make the cover for the sprockets. Here are a few pictures of the frame. The differential is the black thing on the bottom and the motor is the aluminum cylinder on top. The third picture shows the frame placed in the car. This is how it will look when everything is mounted correctly. The box on the end of the motor is the oil sump. It holds the extra cooling oil from the motor and fits very nicely in the old exhaust channel.
Wednesday July 8th:
Motorcycle Battery Pack:
I spent most of the day revising and finalizing the motorcycle battery module design. Lennon, Mike, and I talked a lot about the design. We could not decide between on how to cool the pack. The two designs that we were playing with were to have barb fittings on each module and have a central air blower to send air through the modules or to have fans on each module. The advantage of having individual fans on each module is the simplicity but the modules would not be water tight. The advantage of the central blower idea is that it is more scalable to the car battery pack in the long term and it allows us to seal the individual modules better.
Thursday July 9th:
Motorcycle Battery Pack:
I made a cardboard mockup of the battery module. Mike and I decided that we are going to use a central blower to push air through the modules.
Friday July 10th:
Motorcycle Battery Boxes:
In the morning, Mike bought more polycarbonate plastic and water jet cut the enclosure for one of the motorcycle battery packs. The modules will be cooled by blowing air through them. Each module has two barb hose fitting, one to blow air in and one to let air out the other side. Here is a picture of the final battery enclosure. The tape along the seams is to make the enclosure water tight. Now that the enclosure is complete, all we have to do is wait for the battery welder to get here and then we will be able to assemble one of the packs and try to fast-charge it.
Mercury Milan Test-Drive:
In the afternoon, the whole team drove over to the Costco parking lot to test drive the Milan. The car was really fun to drive! It drives like a normal car but if you pay close attention, you can notice when the electrical systems kick in. The GPS system and the digital dash are really neat too and they work well.
Sunday, July 12, 2009
Friday, July 10, 2009
The team has been preparing for this moment: a 2010 Mercury Milan Hybrid is sitting on our lift, about to be assaulted by all of the tools in our shop. Within three days the most patented car in automotive history will have its hybrid drive system sitting on the floor of our shop in a corner, to be replaced by our 250 horsepower electric bus motor and lithium-iron phosphate battery pack.
With these delays, we have exactly four weeks to finish the mechanical conversion of the car. The new motor cooling system is set up, the 650A controller is tested, the limited slip differential with 7.33:1 gears is ready, the A123 battery pack communications have been resolved and the raw material stock has been ordered. As students, all we have is man-hours to throw at the problem; given the timeline, we’re grateful to our friends at Monster. The details of this intense grind will, of course, be posted for your viewing pleasure.
Driving for 16 hours straight (our only long stop was for dinner), wasn't nearly as painful as I think either of us expected. Due in part to the vehicle we got to test drive the entire way. Ford's improved hybrid system uses a e-CVT and larger, more powerful electric motors. The Milan Hybrid gets an EPA fuel economy rating of 41 mpg in the city and 36 mpg on the highway and can run in EV-mode up to 47 mph. More information:
Not only is the Milan Hybrid an efficient hybrid system, it has the new Synch system, a great navigation system, and (most importantly for nerd engineers like us), an interactive and highly configurable instrument panel geared toward increasing fuel economy. You can even configure the vehicle to display fuel consumption (in L/100km) instead of fuel economy (in mpg). For information about why this is so useful see: http://www.mpgillusion.com/
Here's an image of the instrument panel from http://articles-ford.blogspot.com:
And here I am filling our car up, for possibly the last time, in Springfield, MA:
* Indicates sarcasm
Thursday, July 9, 2009
After we finished wiring up the terminal boxes, we started redoing the wiring inside and under the car. First we pulled out the DC/DC converter and decided to mount it underneath the terminal box in the back of the car. I designed and built a mount for it using sheet metal. I also made room on the mount to attach a relay so that when the car is plugged into an AC outlet, the DC loop is disconnected. The mounting device was also designed so that one cannot easily stick their fingers in any electrical components and get electrocuted.
While I was working on this, Bryan and Dan first had to analyze where each of the wires in the bundle from the DMOC were actually going. After this was documented, they removed the unnecessary bundle and started rewiring.