Yes yes yes yes thanks thanks thanks Max!!! I have been advocation this for a while now, although I still want to see battery powered cars at some point. This is an interim step. There is nothing like racing to bring and develop new technologies and improvements to fruition. I sent emails to the open wheel racing series in the USA, in hoping they would do this sort of thing. I also encouraged them to do it before nascar.

Formula One, in making this announcement, may be renewing my faith in racing. I have been getting jaded, especially with nascar, in their policies and politics. Racing should always relate to and improve all our road going vehicles. This is great news for all.

Note that F1 cars are currently limited to 550kg, of which about 40kg is a tungsten plate that may be mounted in various locations to fine-tune the axle loading for a given race course. The 20kg mentioned above is presumably additional weight. It would make sense to design the energy recuperation system such that it can doubles as ballast instead of the tungsten slab.

Note that pneumatic recuperation, e.g.

http://www.engineer.ucla.edu/stories/2003/hybrid.htm
http://www.all4engineers.com/index.php;site=a4e/lng=en/do=show/alloc=3/id=932

stores the brake energy as compressed air. In the case of an F1 car, the air would be accumulated at elevated pressure and temperatures during braking manoeuvres. The accumulator plenum would be located immediately behind the airbox and above the engine.

Once the accumulator is full or the driver takes his foot off the brake pedal, the air box inlet would be closed quickly (butterfly valve) and the compressed air allowed to flood the air box volume, cooling down in the process. The pressure in the air box would be controlled to e.g. 2 bar absolute (depending on design) for as long as possible. Once the accumulator empties and the pressure in the air box drops below a speed-dependent threshold, the air box inlet is re-opened. The whole process of recuperation and recovery would be over in a matter of seconds, i.e. neither the accumulator nor the airbox would ever be exposed to elevated pressure or temperature for an extended period of time.

The hardest part would be designing intake and exhaust manifolds that permit pneumatic recuperation via suitable switchable valves without compromising available power in regular operation.

Other power-centric hybrid concepts (hydraulic or supercap, probably not battery) permit greater flexibiity but are very hard to implement with such a tight weight constraint.

Of course an increase in efficiency of a couple of dozen race cars will have no meaningful effect on global pollution. And of course auto racing is a spectator sport and merely a form of entertainment.

The point of the article, which was very explicit, was that by opening racing to hybrid technologies, more effort would be put into experimenting with and designing new hybrid solutions. This increase in effort would lead to innovative new solutions, which then make their way down to the commercial level. Since racing is very rule constrained, no effort will be expended by race-car teams on hybrid systems until they know that they will be allowed to use them in competition.

Personally, I don't know enough about the major automakers to guess at how important this "trickle-down-innovation" effect is likely to be. One other effect that people like to mention that incorporating hybrid technologies into high performance vehicles will increase the profile and presige of hybrids. Again, I'm no pollster, so I don't know enough to guess at how important that element will be.

All the same, I see little downside to this development, so good for them. I'm not convinced that this will divert critical engineering talent away from other, more important areas, to the extent that it will have an actual effect on the world at large.

20 kg is less than 50 pounds. Are you sure an extra zero was left off? Any electric, hydraulic, or pneumatic motor of enough power to make a difference would weigh much more than 50 pounds.

Chris Ellis just happens to be the inventor of the Powerbeam (TM?) flywheel. I suspect Chris would like the Powerbeam to be one of the options in the FIA's 'surge power unit' (which is indeed limited to 20kg or 44lbs).

What Joseph may be missing here is the automakers tie, to the teams whixh race in formula one.

Uh, no, once again, I'm not missing that.

Continue from previous posting: Re. pneumatic hybrid
Furthermore, on the compressing stroke of the piston, the compressed air will exit the exhaust poppet valve and enter another valve leading into the compressed air storage chamber. However, the dead volume between the poppet exhaust valve and the spool valve of the compressed air storage will greatly limit the pressure achievable in the compressed air storage, meaning large volume will be required, the volume not availble in a tightly packed F1 car. If one will discard the poppet valves altogether and use spool valves instead, then one would run into the problem of heat damage and carbon sticking of the spool valve during engine combustion. Ceramic spool valves would be a possibility, and the high heat will burn off carbon deposit and ceramic is self-lubricating at high temp, but at 10,000+ engine rpm, can brittle ceramic withstand such repetitive accelerating stress?

Oh, and I forgot, an engine downsizing will mean transmission downsizing also, since your electric motors will handle a lot of the torque previously from the transmission and the differential. So, you'll have even more hybrid powertrain wt. to play with. In a vehicle, the weight of one component will affect the weights of every other components. If the rule will be revised to instead of allowing 550kg empty weight limit, but to allow a fixed gross weight limit INCLUDING FUEL, as judged by the size of the fuel bladders, and since the hybrid will save a lot of fuel weight, then you will have even more weight to play with for the hybrid version, and that's only fair.

Roger -

(a) F1 engines rev up to 19,000 RPM. They use progressive pneumatic valve springs rather than metal coils, because at those ludicrous speeds there is no other way to ensure continous contact between cams and tappets. Note that F1 engines run at compression rations of 16 or so, because at high RPM, the fuel doesn't have time to knock anyhow. Besides, the engines only have to last for two races.

(b) Pneumatic recuperation implies that the pistons compress the cylinder charge with the exhaust valve open. A cam phaser is used to open the valves only once the in-cylinder pressure exceeds the pressure in the manifold. A one-way valve in the accumulator ensures a minimum pressure of several bar during the recuperation phase. The regular exhaust path is blocked during this time, e.g. using a suitably adapted wastegate-type valve (one of the harder component puzzles).

As you rightly point out, a key requirement during this time is that the exhaust valves of the other cylinders must stay closed despite the very high back pressure in the exhaust manifold. For example, at 16 bar back pressure, a valve with a diameter of 40mm and a valve stem of 8mm would be exposed to about 2000N force. Actual closing forces are anyhow higher and defined by the requirement to lift the valve quickly so the tappet maintains contact with the cam as that rolls away.

(c) Ceramic valves are a bad idea. Not only are they brittle but they are poor heat conductors. The high temperatures can cause premature ignition, but they will certainly reduce the mass of the fresh charge and hence, engine power. Racing valve stems are long and partially filled with sodium to act as heat pipes.

(d) During recuperation, the electronically controlled fuel injection would of course be cut, as would voltage to the spark plugs. In a four-stroke engine in recuperative braking, the second and third strokes of each cycle do no useful work - cp. cylinder deactivation. Even so, a 3.5L engine running at 15,000 RPM will still pump ~440L of air per second (neglecting dynamic boost in the airbox due to the high vehicle speed). Note that even today, the driver has to downshift during the brake process to maintain high engine RPM.

Compressed adiabatically to 16 bar, the required volume shrinks to ~14%, i.e. ~60L per second, with a temperature of ~360 deg C. The maximum air mass that can be pressurized is limited primarily by the available accumulator volume (a hot pressure vessel), which must be maximized by adapting the shape of the vehicle body. Additional brake power, if required, must be provided mechanically.

As soon as the accumulator is full or the driver takes his foot off the brake pedal, the valves in the exhaust re-open. F1 cars do not have catalysts, so the excess back pressure can simply be blow off. Fuel injection and voltage to the ignition are re-applied.

Note: for safety, the driver should de-activate recuperative braking before heading into the pits. In the event of a crash, an accelerometer should trigger a pop-off procedure to vent the excess pressure away from the driver.

(e) This reservoir of pre-compressed air is used to briefly supercharge the engine during the next acceleration phase. In a race car, this occurs almost immediately as the vehicle exits a bend. During the intake stroke, the piston performs a modest amount of positive shaft work. The increased air mass allows a greater fuel mass to be combusted, provided the engine is sturdy enough to briefly withstand the greater peak pressures.

In an F1 car, each cylinder has a simple straight intake pipe terminating in the air box. Therefore, boosting intake pressure means blocking that off and filling it with air from the accumulator such that the desired boost pressure is maintained. The adiabatic expansion into the large air box allows the compressed gas to cool down. If required, an air-to-air intercooler may be placed between the vent throttle on the accumulator and the air box, e.g. leveraging the air stream that would otherwise have to flow around the blocked air box inlet.

Naturally, supercharging can only be maintained for a period shorter than the brake period, since the mass flow is now higher. Once the pressure differential across the block-off valve across the regular air box inlet becomes positive, it opens back up and normal operation is resumed.

What about in wheel motors? What team has affiliation with Mitsubishi? This is a progressive change. Diesels and hybrids on the track...together perhaps? Trickle down engineering will hopefully work better than the economic kind.

Thanks, Rafael for the wealth of information on the actual working of a F1 racing engine. Everything is so foreign in comparison to that of an everyday auto engine. NASCAR racing, however, is so backward that the engine technology is still in the past, with large-bore V8 pushrod engines. A wise racing governing body should see to it that racing technology should remain relevant to the popular automotive technology at large. The call for hybrid technology in F1 is a welcoming change.

What i find retarded is they have regulations against things like this. And 20 pounds of braking storage.. 3 years from now? Sounds weak.. why not just remove the rules?

That is a lot of the problem right now is the obsession with regulating things to death.

aa2 -

no-one is forcing you to pay any attention to F1. It purports to be a motor sport, a competition between drivers more so than one between engineers. Over they years, there have been many rule changes, in response to deadly crashes and in response to patented innovations that yielded an unfair advantage to certain teams.

Btw, turbos were limited to 1.5L displacement but managed 1500hp @ 12500 RPM. They completely dominated NA engines until they were disallowed because of the risks inherent in driving engines with that much power. What is perhaps less well known is that these engines actually got far better fuel economy (per kWh, not per mile) than any (non-hybrid) street-legal engine ever has.

At the moment, F1 is still popular but its claim to deliver trickle-down technology has been reduced to shift paddles on the steering wheel. This new idea of recuperative braking will surely be opposed by racing purists but the money and the quality of engineers involved in F1 could well spur a few surprising innovations.