Accelerator
Introduction
The throttle is a mechanism used in Otto cycle internal combustion engines by which the flow of the air/fuel mixture is regulated in the case of carburetor engines or of air in fuel injection engines by means of constriction and obstruction of the intake duct.
Operation
The variation in the filling of the cylinder obtained in this way makes it possible to regulate the mass of mixture introduced into the cylinder in the process of renewing its charge. This variable determines, therefore, the force of the expansion stroke and, finally, the engine torque in each useful cycle. That is, this regulation of the amount of fuel gas admitted in each cycle allows us to adjust the engine torque to the engine load.
This means that, having different load conditions and the same speed, for example, going up a hill at 3000 rpm and going down the same hill at the same 3000 rpm, the different position of the throttle allows us to adjust the cylinder filling and, therefore, the combustion force, with the same speed, always maintaining the air-fuel ratio or lambda factor.
Since the power "Power (physical)") of an engine is equal to the torque multiplied by the engine speed (rpm), this can be increased or decreased by restricting gases for the air/fuel mixture. The term accelerator refers, incorrectly and informally, to any mechanism by which the power or speed of an engine is regulated.
In the diesel engine there is no this restriction mechanism; The fuel flow (diesel or diesel) is dosed instead by means of an injection pump or electronically controlled injectors.
Otto cycle internal combustion engines
In a gasoline combustion engine, the throttle is formed by a valve that directly regulates the amount of air/fuel mixture in carburetor engines or air entering the engine in fuel injection engines, thus controlling the force of combustion in each cycle through the control of cylinder filling, in the process of charge renewal.
This must be done always maintaining a relatively constant air/fuel factor (lambda factor). In a motor vehicle, the control that the driver uses to regulate power is called the accelerator pedal or accelerator.