Transparent plug-in hybrid retrofit for any car
mtsunews.com
mtsunews.com
Anyone know?
Knowing when the car is braking is trivial - the vast majority have a dedicated brake switch wire.
Why do you want to prevent the normal brakes from engaging when regen braking is happening? Since the electric motors are on the rear wheels, braking traction will be severely limited. The majority of braking needs to happen up front due to dynamic weight transfer.
Instead, use a simple brake balance controllers to reduce the mechanic braking effort at the rear and make up for it with the regenerative braking. Brake balance controllers are readily available in the aftermarket, so this is a solved problem.
Admittedly, for a universal application you want to interface with as little of the car as possible.
That said, in the US all cars made after 1995 comply with certain On-Board Diagnostics protocols (OBD-II) so you can interface with several standard systems.
One such sensor available in OBDII is the VSS or the Vehicle Speed Sensor. Check out a device like the Scan-Gauge[1] to get an idea of other sensor that can be interfaced with universally. It would be trivial to run some wire under the carpet and plug into the OBDII port to give the hybrid system access to all kinds of engine & sensor info.
I wasn't saying that. Let me rephrase: The way the video describes the controller (the one in the trunk)...
It would not be able to tell the difference between braking and simply slowing down, for example going uphill - or worse, driving in water - hitting the brakes when going through standing water can be disastrous.
As for the accelerometer detecting moving forward it has some nasty feedback going on there, since it detects its own motion. Plus imagine going downhill and the read engines think you hit the gas so they cause you to go even faster.
That said, it should be possible to interface with the engine there are plenty of signals that can be used (throttle, rpm, etc).
Agreed. I was simply saying that from what I got from the video, it is not interfacing with the vehicle. Maybe it should be but it seems that is not what they are building. I'll leave it to the people that have been working on it for 4+ years to make that decision as they certainly know a whole lot more than I do.
It seems like you'd still get 50% of the benefit and have no potential to interfere with the brakes.
Just a button wouldn't work; how would the system know how much braking to apply? You would need something with variable input. Even then it would require considerable practice, I think, on the driver's part; it would be something like trying to control braking with the parking brake while the vehicle is in motion (which I have had to do on one occasion when my regular brakes failed--it's not at all easy).
But teeing off of the brake line with the pressure sensor is hardly impossible.
Yes, that would work, provided it didn't affect the signal going to the vehicle's own computer. (It doesn't seem like it should, but I spent some time as an automotive engineer, and one thing I observed is that the car will do lots of things you don't expect.)
[Edit: after seeing another comment below I'm not sure the switch would be enough; you need to know how hard the brake pedal is being pressed so you know how much braking the driver is requesting and can adjust the amount of regen accordingly. But there are ways to do that as well, as the commenter notes.]
> Why do you want to prevent the normal brakes from engaging when regen braking is happening?
Because the normal brakes prevent regenerative braking (regen) from happening. Both processes convert the vehicle's kinetic energy into something else--regen into electricity, normal braking into heat. You can't convert the same kinetic energy into two things at once, so any energy converted into heat by normal braking is unavailable for regen.
> The majority of braking needs to happen up front due to dynamic weight transfer.
Which will limit how much regen you can get, since it can only withdraw energy if it is actually slowing the wheel down. It may still be worthwhile to do regen, but not nearly as much as if you could do it on all four wheels.
> Instead, use a simple brake balance controllers to reduce the mechanic braking effort at the rear and make up for it with the regenerative braking.
Are these controllers dynamic? That is, can they adjust the balance depending on whether regen is happening or not? There will be circumstances when regen can't happen, or can't take all of the energy available (for example, if the battery is close to full or unable to accept charge fast enough).
If the controllers are dynamic, then I agree you could put together a solution this way. But you would still need to do a lot of tuning of the controls. One thing I would be worried about if I were doing this is being able to get everything tuned smoothly without having access to the code and calibrations in the vehicle's own computers.
With regards tot he transmission question: my car (and many others) allow me to select the gear even though it has an automatic transmission. In my car it's called Autostick, other cars it will be something else; sportshift maybe.
In this way, I can ensure the gear will be optimal for gasoline consumption.
Also, perhaps in the future, a model can be made to incorporate regenerative breaking.
Depending on the efficiency of the implementation I'm sure (as well whether or not this is a valid study at all), but it seems that electric cars are able to do it significantly cheaper than gas. So those savings are probably not spend at the electrical outlet.
A properly designed solution would enable the opposite; keeping the car in an optimal gear for longer. A hybrid works best when the batteries run where they have the greatest advantage against the fuel.
These batteries and controllers need to find another place. On the roof of the car, perhaps, unless you're an outdoor sports person and need racks for bikes or a kayak?
Maybe one day the frame can be made out of batteries.
The size of the final version should be about the size of a carry-on bag.
How about put the motors in a new differential? It'd take a larger casing, but you could apply the electric torque to each wheel too.
Think RWD cars. Floor it on a curve and you can go into a tailspin. But RWD cars are designed as having power on the rear while FWD cars have not, so the effect could be much more dramatic with much less force.
It's not that complex to solve... as long as you have access to the various sensors (Hall, inertia... if any) and actual decisions of the ECU, and design data (i.e everything the manufacturer has), but piggybacking on it is quite an endeavor. And it has to be done for each car model since they all differ dynamically and in hardware.
For example (oversimplification), FWD cars have their suspension balanced to be stiffer on the rear because it gives the front more grip (and the reverse is true for RWD cars). This stiffness would not usually result in a loss of grip under load (e.g in a corner), but adding a force to the wheel may overcome the remaining grip and throw the car into a tailspin.
Applying a rotating force on the wheels creates a pinching effect, momentarily changing the parallelism. This effect is sufficiently noticeable that some cars are designed with wheels not parallel at rest, so that when you drive on the highway (and thus apply some power to the wheels) the wheels are parallel.
There are countless scenarios where things can go wrong because you're simply doing something that the car was not designed to handle.
(For the curious, the Forza Motorsports series has a nice sandbox mode allowing to experiment with various settings by changing them on the fly, and the inline help explains succinctly the impact of each knob on your car's behavior)
Hybrids do well on gasoline because they have efficient undersized engines combined with light weight and excellent aerodynamics. This retrofit wouldn't change any of those things so I doubt it would have the claimed mpg benefit on a long drive. With a big battery pack, I could see it boosting MPG in city driving but it doesn't have gearing to use the motors at high speeds like highway driving. The big battery pack hurts city driving because you need to accelerate and decelerate that added mass.
It reminds me of similar retrofits that might be comparable and easier:
1) Replace the alternator (or AC) with a small 6-10hp motor. This is like a DIY version of the Honda IMA. I think GM was promoting something like this. You're limited by the power a belt can transmit, but it does go through the transmission and allows easy stop/start of the engine (ex: at a traffic light).
2) Remove the rear drive-shaft from a 4WD like a truck and attach a motor to the differential. This is also somewhat easy and a truck is better equipped for carrying batteries. There was a Jeep design that did this. Stay in "4wd" without applying power to the motor and it's like a front wheel drive. The downside is that the motor isn't geared so it's only good for one speed range (perhaps low end torque).
Unfortunately, both designs are just mild hybrids. To really go far enough with the motor you need lots of batteries. For example, the 80lb NiMH pack in my Insight can barely go a few miles. Regen makes sense but you lose a surprising amount of energy charging/discharging. I get the best gas mileage trying not to use the hybrid systems (even in city driving).
To me it is the same idea as the electric bike retrofit kits by Bionx.
If I recall, that model Accord wagon had rear drum brakes.
edit: yep, it does have rear drums. I'm VERY curious to see how they intend to make this work for disc brakes, especially when the calipers have to wrap around that huge assembly.
The idea of rolling down the road and having a few magnets come flying off also scares the daylights out of me.
You're more likely to notice disc brakes -- they are more visible from outside the car and require slightly more frequent maintenance -- so you may not be able to think of many cars with rear drums.
The majority of OLD cars. Modern cars are switching to disk brakes all around. The best design is actually a hybrid brake - it has a drum brake in the middle used only for the emergency brake, and the outer edge is flat for the disk brake.
Electric motors are great at low speed torque which is why it helps the gas milage so much with city driving. I bet it also can take a chunk out of the 0-60 time.
The next step is to add power regeneration during braking.
If this is practical, I am sure the big car manufacturers will just do an end-run around any patent with their own tweaks and then it will just be a lawsuit battle.
Then you have the issue about a filling station.
Then considering taxes on fuel are nearing 50% of fuel cost, you're right around where this conversion gets you. (I don't know if NG at the pump would be taxed)
Electric solutions work around the issue of fuel cost and filling locations nicely. Electricity is cheap and basically available in every garage. If you have a garage. Having a hybrid electric works around the issues of limited range and cold weather.
So charging stations wouldn't be necessary and taxes wouldn't be an issue either.
So if you are looking for prices, check companies located there.
Good work, of course, but, if you tasked any capable team of engineers to build a DC brushless motor as a retrofit into a car wheel this is what you would get. In fact, there are thousands of teams all over the world that could do this inside of six to twelve months with equal results.
[0] http://carscoop.blogspot.com/2010/08/new-peugeot-3008-hybrid...
Make the rims part of the engines (or the opposite).
Electric cars face big challenges in terms of cost and weight; I expect that a design like this, which increases both, is far, far away.
The Tesla cars, which cost a huge amount of money, don't do things this way. The Toyota hybrid system, probably the most developed in the world at the moment, doesn't do things this way. The people who designed those things were smart people.
For one motor torque scales with the square of radius, so a relatively light pancake motor can have quite high torque. You can also downsize the friction brakes thanks to regenerative braking. Finally you can distribute your motors across all the wheels.
In exchange you get a drivetrain with one moving part per wheel (yes, leaving aside bearing needles, you pedant!).
I don't foresee this making its way into sports cars, but I could see the minivan of the future having a drivetrain like this.
http://en.wikipedia.org/wiki/Wheel_hub_motor
http://en.ekopedia.org/Wheel_motor
This company is doing something similar:
http://www.proteanelectric.com/
Let the law suits begin...
Less efficient, much cheaper, and hopefully less environmentally harmful.
I like what this solution offers - a chance for someone like me who will probably never buy a new car to easily modify an older car to run at least partially off electricity.