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JOSÉ LUIS DÍAZ HERRERA - Barranquilla (COLOMBIA)
To end up understanding this, let us clarify some terms and concepts.
The motor of internal combustion, is any machine type that he/she obtains mechanical energy directly of the chemical energy taken place by a fuel that burns inside a combustion camera.
Motors of internal combustion of four types are used: the recurrent motor Otto, the motor diessel, the rotational motor and the combustion turbine.
The introduction of this motor took almost immediately to the development of the automobile that would have been practically impossible with the voluminous machines of vapor.
The motors Otto and the diesel one have the same main elements. The combustion camera is a cylinder, in general fixed, closed in an end and inside which a very adjusted piston slips to the interior. The crankshafts have heavy steering wheels and counterbalances whose inertia reduces the irregularity of the movement of the axis. A motor can have from 1 to 28 cylinders.
The system of pumping of fuel of a motor of internal combustion consists of a deposit, a bomb of fuel and a device that it vaporizes or it atomizes the liquid fuel.
He/she calls himself carburetor or injectors to the devices used with this end in the motors Otto. In the motors of several cylinders the vaporized fuel leads to the cylinders through a tube ramified called admission collector.
Many motors have an escape collector or of expulsion that transports the gases taken place in the combustion.
In the decade of 1980, this system of feeding of a mixture of air and fuel has been displaced by other systems more already elaborated used in the motors diesel. These systems, CONTROLLED FOR COMPUTER, they increase the saving of fuel and they reduce the EMISSION OF TOXIC GASES.
All the motors have to have a form of beginning the ignition of the fuel inside the cylinder. The device that produces the ignition is the spark plug, a driver fixed to the superior wall of each cylinder. The spark plug contains two separate threads among those that the current of high voltage an electric arch that generates the spark that he/she lights the fuel inside the cylinder takes place.
Since the combustion produces heat, all the motors should have some type of refrigeration system. Some stationary motors of automobiles and of airplanes and the motors fueraborda are refrigerated with air.
In other motors refrigeration is used by water, what implies that the cylinders are inside a carcasa full with water that in the automobiles it becomes to circulate by means of a bomb. The water is refrigerated when going by the sheets of a radiator
The conventional motor of the type Otto is of four times, that is to say that the complete cycle of the piston has four phases, two toward the closed bolster of the cylinder and two back. The half efficiency of a good motor Otto is from a 20 to 25% (that is to say that the fourth part of the heating energy only transforms in mechanical energy). 75% vanishes in heat by means of the radiator and absorbed by the environment.
In theory, the diesel cycle differs of the cycle Otto in that the combustion takes place to a constant volume instead of to a constant pressure. Most of the motors diesel also have four times, although the phases are different from those of the motors of gasoline.
The efficiency of the motors diesel that depends on the same factors in general that the motors Otto, is bigger than in any motor of gasoline, ending up overcoming 40%. The motors diesel are usually slow motors with crankshaft speeds from 100 to 750 revolutions per minute (rpm or r/min), while the motors Otto works from 2.500 to 5.000 rpm. Nevertheless, some types of motors diesel can reach the 2.000 rpm.
As the grade of compression of these motors it is from 14 to 1, they are in general heavier than the motors Otto, but this disadvantage is compensated with a bigger efficiency and the fact that they use cheaper fuels.
With an appropriate design it can be gotten that a motor Otto or diesel works at two times, with a time of power each two phases instead of each four phases.
The efficiency of this type of motors is smaller than that of the motors of four times, what implies that the power that you/they take place is smaller than half of the one that produces a motor of four times of similar size. Very used in the motos motors.
In the decade of 1950, a motor of internal combustion was developed with a revolutionary design that used a triangular rotor that rotates inside an oval camera, instead of a piston and a cylinder.
The mixture of fuel and air is absorbed through an aspiration hole and it is caught between one of the faces of the rotor and the wall of the camera. The rotation of the rotor compresses the mixture that lights with a spark plug. The gases are expelled through an expulsion hole with the movement of the rotor. The cycle takes place once in each one of the faces of the rotor, producing three phases of power in each turn.
This motor type is compact and slight in comparison with the motors of pistons, for what won importance during the crisis of the petroleum in the decades of 1970 and 1980.
Also, it works almost without vibrations and their mechanical simplicity allows a cheap production. It doesn't require a lot of refrigeration, and their low center of gravity increases the security in the conduction.
A variant of the ignition motor with spark plugs is the motor of stratified load, designed to reduce the emissions without necessity of a system of recirculation of the resulting gases of the combustion and without using a catalyst.
The key of this design is a camera of double combustion inside each cylinder, with a hall that contains a rich mixture of fuel and air while the main camera contains a poor mixture. The spark plug lights the rich mixture that in turn lights that of the main camera.
The maximum temperature that is reached is enough as to impede the formation of OXIDES OF NITROGEN, while the half temperature is the enough one to limit the emissions of MONOXIDE OF CARBON AND HYDROCARBONS.
Also, the environmentalist concerns on the emissions of escape gases, the jams in the cities and the noise have made that in the developed countries DEDICATED LAWS are approved to REDUCE THE NEGATIVE IMPACT OF THE VEHICLES. (From 1995 cars were not manufactured with carburetor, alone the electronic injection was used). The employment of CATALYSTS AND MOTORS OF UNDER CONSUMPTION he/she has for objective to reduce the noxious emissions.
The development of slighter and more aerodynamic automobiles has the same effect, since it reduces the consumption of fuel. The measures dedicated to increase the security of the vehicles, with systems like belts of security or airbag and improvements in the construction of the chassis, they have supposed another challenge for the industry of the automobile along the last 25 years.
The engineers use electronic equipment of high sensibility to examine the vehicles during the design and the production of a new automobile. All their systems, including the motor, the controls, the transmission and the suspension, they are carefully examined during the production process to get the biggest quality and security of the final product.
At the beginning of the XXI century, the automobiles face two fundamental challenges: on one hand, to increase the security of the occupants to reduce this way the death toll of the traffic accidents, since in the industrialized countries they constitute one of the first causes of mortality in the population non old man; on the other hand, to increase their efficiency to reduce the consumption of resources and the atmospheric contamination, of which you/they are causing one of the main ones. (Effect hothouse).
In the first section, besides improving the protection offered by the chassis, diverse mechanisms of security have been developed, as the antifreezing system of controls (ABS) or the airbag.
As for the second aspect, the shortage of petroleum and the increase of the prices of the fuel in the decade of 1970 encouraged in their day to the mechanical engineers to develop new technologies to reduce the consumption of the conventional motors (for example, controlling the mixture air-fuel by means of MICROPROCESSORS or reducing the weight of the vehicles) and to accelerate the works in alternative motors.
To reduce the dependence of the petroleum it has been tried to use renewable fuels: in some countries hydrocarbons of vegetable origin are used, and the use of hydrogen is also studied that would be obtained starting from the air using, for example, the solar energy. The hydrogen is a very clean fuel, since its combustion produces WATER EXCLUSIVELY.
Among the alternatives to the conventional explosion motors, the electric motors seem to be the most promising.
The turbine motor continues without being practical to commercial scale for its high costs of production and other problems; the motor modernized Stirling still presents technical obstacles, and the motor of vapor, with the one that was experienced in the decades of 1960 and 1970, it demonstrated to be not very practical. On the other hand, the revolving motor Wankel whose consumption is inherently bigger, it has continued taking place in few quantities for applications of high power.
The important advances in the technology of batteries have allowed to manufacture electric automobiles able to develop superior speeds to the 100 km/h with a great autonomy.
This type of vehicles is extremely clean and silent, and it is ideal for the urban traffic. Also, as most of the electric power stations it uses coal, the massive use of the electric vehicles it would reduce the demand of petroleum.
The disadvantage of the electric automobiles is its high current cost (that, among other reasons, it is caused by the first floor number of produced units) and the necessity to create an appropriate infrastructure to recharge the batteries.
It is advisable to use in the motors of high compression a gasoline that burns of uniform way and total to prevent the detonations that are the sounds and the damages caused by the premature ignition of a part of the fuel and of the air in the combustion camera.
The antiknock properties of this fuel are related directly with their efficiency and they depend on the octane index.
As much as adult is this index, minor it is the probability that the fuel produces detonations. and any gasoline can improve by means of the addition of substances like the TETRAETILPLOMO.
However, since he/she was discovered that the emissions of LEAD of many gasolines are dangerous (among other effects, they produce the increment of the sanguine pressure) the investigation in new ways has been intensified of reducing its detonation.
The unleaded gasoline appears at the beginning of the decade of 1970 as a result of the increase of the public understanding about the atmospheric contamination.
From 1975 all the new automobiles manufactured in United States have catalysts that reduce the polluting emissions. Since the lead ruins the catalyst, you began to produce unleaded gasoline.
The developed countries have also followed this tendency, mainly burdening with additional taxes the use of the fuel with lead.
