A modern car consists of many subsystems that ensure the smooth and smooth operation of this type of transport. An important place in the functional chain of the engine is occupied by the accelerator. This is the name of a device that allows you to regulate the process of supplying fuel to the cylinder system.
What is an accelerator for?
Translated from Latin, the term "accelerator" literally means "accelerator". With regard to automotive technology, this is the name of a special flap, by means of which the supply of the air-fuel mixture to the combustion chambers of the engine cylinders is regulated. The damper is directly connected to the gas pedal. By pressing the pedal, the driver changes the pressure in the cylinders. If the pressure rises, the pistons begin to move faster. Through the connecting rods, the force is transmitted to the crankshaft, and from it to the transmission. You can control the speed of rotation of the wheels by switching to higher or lower gears.
The accelerator is used in both carburetor and injection engines. The difference in the operation of this device lies only in the method of supplying the working mixture.
The carburetor is the part of the vehicle's fuel system, where air and gasoline are supplied to form a combustible mixture. By pressing the accelerator pedal, the driver controls the supply of this mixture to the cylinders.
An injector is an injection system where the supply of fuel to the combustion chamber of a single cylinder is controlled by means of injectors. The injection-type engine guarantees a more accurate metering of the fuel mixture.
A gas pedal is provided to control vehicle acceleration. It is necessary to press it very hard - and a kind of "dips" are formed in the carburetor engine: the air volume becomes excessively large. A special accelerator pump allows you to cope with this problem. The injection engine is devoid of such a disadvantage. Here, special sensors are used to control the position of the throttle valve and accelerator pedal. The injection system allows you to significantly save fuel.
In cars equipped with turbo engines, the design of the accelerator is more complex. In such systems, the uniformity of the piston stroke is achieved through the use of high-pressure pumps and additional nozzles.
Some inexperienced drivers often depress the accelerator pedal sharply and forcefully unnecessarily. They are driven by the desire to accelerate faster on a good road. This should not be done: any sharp pressure on the gas pedal increases fuel consumption many times over. A car with this operating mode of the accelerator may well become two or three times more "gluttonous".
How the accelerator works
What happens when you press the accelerator pedal lever? In a carburetor engine, at this moment, the dampers responsible for supplying air to the engine open slightly. The more the shutter is open, the more fuel is consumed: coming through the fuel jets, it does not have time to evaporate properly. Within the carburetor, air is mixed with fuel. In this case, a combustible mixture is formed. The more this mixture is fed into the cylinders, the stronger the pressure inside the engine. In accordance with this, the torque also increases, the crankshaft speed increases.
One has only to sharply press the accelerator pedal - and the fuel mixture is immediately depleted. The accelerator pump immediately turns on, it injects a little fuel into the carburetor, which increases the degree of enrichment for a fraction of a second.
On diesel engines, the accelerator pedal is directly connected through the regulator to the high pressure pump. On such an engine, air is supplied in a constant mode, only the amount of fuel supplied per cycle changes. The plungers of the fuel pump are responsible for the cyclic feed. The fuel supply cutoff point is changed by turning the plunger. In fact, the accelerator pedal is used to control the plunger itself.
On turboprop and turbojet engines, the accelerator may be in the form of a handle that is operated by hand. These engine types are also characterized by the use of high pressure pumps. In this case, the uniform operation of the engine is ensured by a system of several injectors: through them, when the accelerator lever is actuated, fuel is injected in turn.
Electronic accelerator drive
Controlling the accelerator via the cable drive is very simple. The driver squeezes the gas pedal, the traction, depending on the angle formed, opens the damper by the same amount. To change the torque of the propulsion system, it is necessary to influence other parameters of the engine mode (for example, at the moment of fuel injection and the moment of ignition). Such influence is ineffective and not entirely correct.
The design of the electronic accelerator drive is thought out so that the throttle valve moves not due to the work of the rods and cable connected to the gas pedal, but through an electric motor that operates under the control of electronics. In this case, there is no conventional mechanical connection between the throttle lever and the throttle.
Control actions on the accelerator are determined by:
- by the actions of the driver;
- generator load;
- the state of the braking system;
- engine start conditions;
- power limitation.
The electronic drive system includes:
- accelerator pedal module;
- damper control module;
- the engine control unit;
- control lamp.
When the driver changes the position of the accelerator pedal, an electrical signal is generated and sent to the throttle control system. This design allows the control unit to influence the amount of torque even when the driver is not using the accelerator pedal. This is sometimes necessary to ensure fuel economy or traffic safety.
The driver also has the option of mechanical throttle control. In this mode, the driver directly controls the position of the accelerator pedal. In this case, the engine control unit cannot influence the position of the throttle valve in any way.
The electronic accelerator drive gives the car a new quality, which boils down to the fact that the control system responds to the wishes of the driver.
One of the advantages of the electronic system is the automatic processing of external and internal influences in order to establish the magnitude of the engine torque. The built-in algorithm itself is able to calculate the required torque value.
Accelerator pedal module
This subsystem of the modern car is critical for engine trouble-free operation. Such a module, by means of sensors, constantly determines the position of the gas pedal, after which it continuously transmits control signals to the engine control unit.
The accelerator pedal module includes:
- accelerator pedal;
- pedal position sensors;
- additional resistance;
- power wires.
It is worth applying an effort to the accelerator lever - and immediately the sensors responsible for the position tell the control unit what the driver's intentions are. This unit gives the command to close or open the damper. At the same time, the amount of fuel that is injected into the cylinders is adjusted. The electronic system additionally takes into account third-party parameters: data from cruise control, forced idle, air conditioning, traction control system, and so on. The use of an electronic drive expands the possibilities of controlling the parameters of the engine operation and removes part of the information load falling on the driver.