Major advances in electronics are revolutionizing the way cars steer, handle and brake. Automotive News Europe's Georg Auer spoke to Fritz Indra, group director of advanced drivetrain technology for General Motors, about the changes and the implications for automakers. Edited excerpts follow.
With the increase in electronically controlled powertrains, what is the future for hydraulics?
We want to get rid of all hydraulics completely. Hydraulics cannot get cheaper so it is not good that new automatic transmissions are still controlled hydraulically. It is much better to use only one type of energy, electricity. With hydraulics you can get leaks, but with electronics you cannot.
Do you think consumers would like an electronic steering wheel with no mechanical connection to the wheels?
Electric steering had problems at the start but having an electrical system makes everything much simpler. First, we can do without a servo pump and its V-belt, hoses and connectors. In theory, we are able to brake 100 percent electronically, but again everyone is wary. Braking and steering is a question of having 'feel.' When you use an electric brake or electric steering for the first time, it does not give the same feel of the road. The art is to engineer that 'feel' and keep the fun of driving a car.
Will new electronically controlled powertrains create problems for repair shops?
With the new on-board diagnosis systems, the functions carried out by the usual diagnostic station in the workshop are incorporated into the car. This actually simplifies things for the mechanic in the repair shop.
He will follow what the OBD and the diagnosis test station tell him. The mechanic of the future will even have less work to do on the engine than now.
What happens when a connector goes out of order?
There are safety circuits to prevent accidents. We want to convert everything mechanical except the engine itself to electronics, including the hand brake, gearshift and clutch.
Emission laws are so strict, even the most finely calibrated measuring tools cannot show correct results over a long span of time. How can these tools stay correct in a moving car as part of the OBD?
The modules of the on-board control system are not the same as in the diagnosis station in the repair shop of a car dealer. The OBD continuously compares results from sensors and has full running control.
It only has to show that something is out of order, not give the exact values. But really, the car should not show any wear within 100,000 miles. If there is a change from the regular state the driver gets a signal. In the repair shop, the OBD is plugged into the diagnosis station, which locates the fault.
What are your views on direct-injection gasoline engines?
The more cylinders you have, the more difficult direct gasoline injection is, which is why we are not seeing big DI engines.
Anyhow, the enthusiasm over DI gasoline engines has petered out. If you take an engine with a small displacement, it is difficult to find a sensible position for the injector nozzle and the spark plug.
A small engine mainly runs under full load and only very rarely in partial load, but it is only under partial load that fuel economy in the DI system materializes.
If you take a large DI engine, the temperature of the exhaust gas is not high enough for the catalysts to work properly. So there is only a very narrow zone of four-cylinder engine displacements - between 1.6 and 2.2 liters - where the benefits of DI technology may be seen.
You may have the best engine in the world, but if you cannot control the emissions it is good for nothing. We have to expect that emission limits will be decreased.
So how will engineers find an answer to this?
With large engines, cylinder cutoff (where half the cylinders are temporarily put out of action) is the best method to reach good fuel economy without too many emissions problems. With smaller engines, better control of the valves helps, particularly variable valve actuation. The Orbital system of assisting DI with additional air injection gets very interesting results in fuel economy and emissions, but it is very complicated.
Complicated meaning expensive?
We now have an interesting situation in that the internal combustion engine is becoming more and more expensive. That opens the door for new technology because the more expensive the old technology is, the better the chances for new technology.
The internal combustion engine has undergone surprisingly little change. Actually, the multivalve technique has come to the point where it is better to revert to two or three valves so that the injector and spark plug can be ideally placed in the ignition chamber.
Why hasn't anyone ever tried to put the spark plug into the center of the piston instead of the cylinder head?
When I give my lectures at Vienna Technical University on racing engines, I say the spark plug should be placed in the center of the piston. But no one has come up with a viable method of doing this.
The next best solution is to elongate the spark plug so that it gets the spark to the center of gravity in the ignition chamber.
Our way of looking at things is changing fundamentally. We don't need so many valves now to get very good technological results.
We don't need engines revving to 8,000 rpm. We do need engines that provide their highest torque at 1,000 rpm because then you can use very high transmission ratios that allow the engine to turn very slow but with high output of torque like a steam engine.
Is that possible with a gasoline engine without a compressor?
Why without? The diesel engine depends on a supercharger to work effectively. We are all working intensively on adapting the variable turbocharger that works so well with diesel engines to the gasoline engine so that it gets better low-end torque.