EQUIPMENT
Trends
FUTURE ICE
LONG TO THE DEAD POINT
MAXIM NETS
Internal combustion engine for over a century. Skeptics already twenty years ago believed that the creations of Nikolaus Otto and Rudolf Diesel reached a peak in development. But it’s too early for gasoline and diesel units to resign. After all, the reciprocating engine has changed a lot: unprecedented technologies have been worked out, more durable and lighter materials have appeared. The valves and rotors of ceramic turbochargers are no longer surprising anyone. It is too early to talk about the wider distribution of this material. The main activity of engine designers is improving mixture formation and reducing unavoidable losses.
Let's try, based on modern serial and promising developments, to look into the future of ICE.
FUEL INJECTION
The era of the carburetor has long gone, and electronic injection of a traditional design does not have long to live. It is tempting to supply gasoline not to the intake manifold, but directly to the combustion chamber, as in diesel engines.
The first to succeed were the Japanese, who tested GDI engines (Gasoline Direct Injection - direct injection of gasoline) on the Mitsubishi Karisma model. At light loads, the engine runs on very poor mixtures. It’s hard to set fire, so fuel is injected at the end of the compression stroke, and cunningly shaped pistons direct the mixture directly to the spark plug electrodes. The so-called layer-by-layer mixture formation takes place in the combustion chamber. At medium and high loads, fuel is supplied twice: during the piston stroke down and at the end of the compression stroke.
Ten to fifteen percent gasoline savings in GDI engines compared to conventional injection engines are especially noticeable in modes when the unit is working at a third of the force. The enriched mixture is fed directly to the spark plug electrodes, and clean air is near the cylinder walls. But there are no free cakes - during combustion, the temperature rises sharply, and with it the amount of nitrogen oxides (NOx) in the exhaust gases. We have to put an expensive neutralizer in the exhaust system, which turns harmful oxides into harmless nitrogen and oxygen. In addition, the engine with direct injection requires fuel with a minimum amount of sulfur - ordinary gasoline will quickly disable the neutralization system.
Some firms have already developed engines with direct injection, capable of digesting ordinary gasoline. Control systems ensure that in all modes the mixture is homogeneous. Therefore, a three-component converter can cope with nitrogen oxides alone. However, you have to pay for it with a slightly higher fuel consumption compared to GDI engines. But the owners of the BMW 7 Series or the new Porsche Carrera, which is due to appear in a year, can come to terms with this.
Improvement of fuel equipment is one of the promising areas for designers of diesel engines. In the near future, high-pressure pumps, even electronically controlled, will increasingly give way to pump nozzles. After all, the operating pressure of the injection pump is much lower. But pump nozzles also have disadvantages. Even under electronic control, they cannot inject fuel at any time, unlike the common rail common rail system. But the pressure in the ramp is lower than in the pump nozzle. Therefore, in the near future both designs will be used.
ATTENTION, AIR!
One way to increase torque and power is to change the air pressure at the inlet. Many firms are already making variable geometry intake manifolds. At minimum speeds, air goes to the combustion chamber along a long path, at higher speeds a short pipeline opens.
In the short term, the length of the intake channels will change not stepwise, but smoothly. For example, this design already works on BMW engines. Electric rotating drum per second is able to increase the air path from 231 to 673 mm. A long channel works up to 3500 rpm, and with a speed increase it shortens.
In addition, Bavarian minders suggest changing the height of the valve depending on the mode of operation of the motor. "Valvtronic" (Valvetronic) has already registered on production engines. An additional eccentric shaft controls the levers that limit the stroke of the intake valves. A throttle that creates additional air resistance is no longer needed. True, they have not completely abandoned it yet - it works during heating and in emergency mode. Manufacturers claim that at low and medium loads Velvtronic saves about 10% of fuel. Other companies are already running similar designs.
Another way to control the air entering the cylinders is to shift the valve timing. By turning the camshaft, you can change the moment of opening and closing the valves. This improves the filling of the cylinders, and therefore, the power and torque increase, fuel consumption is reduced, and the amount of harmful substances in the exhaust gases is reduced.
Many companies offer options for such designs, some have already taken root on production engines. By the way, the original domestic design was tested for VAZ engines (ЗР, 1999, No. 2) and, possibly, will appear on promising models.
OTTO AND DIESEL IN A VOLTAN COMPANY
In the motor cabinets of BMW, an engine with an electromagnetic valve actuator is already being tested. Instead of camshaft cams, solenoids will open and close valves, naturally, under vigilant control of electronics. The control program, depending on the speed, load, temperature, at the right time will open and close the valve.
In this motor, another novelty is also hidden, which soon promises to become mass. Specialists combined the starter and alternator, and placed the device directly on the flywheel. The new design (by the way, similar solutions were used even before the war, in particular, on German DKV) save valuable space under the hood, in addition, drive belts and gears are not needed.
In the future, designers will free the engine from some mounted units. First of all, mechanical pumps will disappear, taking away precious forces from the engine. First-born - electric power steering pumps that already work on many cars. The day is not far when the electric pump of the cooling system with variable performance will take its place, which allows it to more accurately withstand the set temperature.
The development of electronic systems is holding back the current 12-volt standard. To set in motion numerous electric drives and electric pumps, a lot of power is needed, therefore it is necessary to raise the on-board voltage threefold. In the near future, the transition to a new standard will begin, and by the beginning of the next decade, most cars will already be "high voltage".
VARIABLE CONSTANTS
Throughout the history of engine building, such an important parameter as the degree of compression was given to the engine at birth for life. But a couple of years ago, SAAB introduced the world to an engine with a moving block head and, as a result, a variable compression ratio (ЗР, 2000, No. 5). To increase the efficiency, it was increased at maximum power and lowered under partial load conditions. The design has not yet received wide distribution, first of all, due to technological problems and high cost. However, the idea continues to excite the minds of engineers.
The original scheme is tested by Mercedes. The head and block are stationary, and the compression ratio changes due to the “displacement” of the dead points (ZR, 2002, No. 3). Specialists are preparing to change another constant - the working volume. This is not about turning off the cylinders, but about changing the geometry. But it’s too early to talk about this.
GAS ATTACK
For the sake of ecology and economy, manufacturers are experimenting with gas fuel. Propane-butane, well known to many drivers, has few prospects, since it is obtained by distillation of oil, whose reserves are not unlimited. Alternatives are methane and hydrogen.
But, unlike propane-butane, lighter gases do not provide a large range. A fuel tank is only enough for a couple of hundred kilometers. To increase mileage, they suggest using not compressed, but liquefied gas. The main problem is that it is not stored for a long time. Within a week, the contents of the container will be reduced by half.
Manufacturers offer a compromise in the form of dual-fuel vehicles that operate, in addition to gasoline, on compressed methane or hydrogen. Gas injectors are installed in the intake manifold near the gasoline ones, and the control system is instructed to monitor the gas supply. Many firms, including domestic ones, deal with this topic (ЗР, 2001, No. 2). However, given the problems that arise, in the near future, methane or hydrogen is unlikely to completely replace gasoline and diesel fuel. So, the brainchild of Otto and Diesel, improving, while maintaining their position.
True, according to forecasts, oil reserves will last for another fifty years, unless, of course, they find new deposits somewhere on the Moon or Mars. In internal combustion engines, worthy competitors should still appear. To begin with - hybrid power plants already entering life, more economical. Probably, it is they who will soon displace the "lone" piston engine. However, hybrids are a topic for another discussion, we will return to it in the next issues.
Gasoline engine 1.4 FSI 16V (Fuel Stratified Injection) with direct injection power of 63 kW / 86 liters. with. accelerates the Volkswagen Polo to 178 km / h, burning on average about 5 l / 100 km.
The system of neutralization of harmful gases for modern diesel engines: 1 - oxidizing converter; 2 - a lambda probe; 3 - control unit; 4 - temperature sensors; 5 - pressure change sensor; 6 - soot sensor; 7 - filter of solid particles; 8 - lambda probe or NOx sensor; 9 - a converter of nitrogen oxides.
Working processes in the combustion chamber with direct injection: a and b are already implemented on serial engines; c - a promising development with a different arrangement of nozzles and candles.
