A machine control unit ( ECU ), also commonly called machine control module ( ECM ), is a control unit type electronics that control a series of actuators on internal combustion engines to ensure optimum engine performance. This is done by reading the values ​​of many sensors in the engine room, interpreting data using multidimensional performance maps (called search tables), and adjusting the appropriate engine actuators. Before the ECU, air-fuel mixture, ignition timing, and idle speed are mechanically arranged and controlled dynamically by mechanical and pneumatic means.
If the ECU has control over the fuel line, then it's called the Electronic Engine Management System (EEMS). Fuel injection systems have a major role to control engine fuel supply. The entire EEMS mechanism is controlled by a stack of sensors and actuators.
Video Engine control unit
Workings
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Most modern engines use some kind of fuel injection to deliver fuel to the cylinder. The ECU determines the amount of fuel injected based on a number of sensor readings. The oxygen sensor tells the ECU whether the engine is running rich (too much fuel or too little oxygen) or running lean (too much oxygen or too little fuel) compared to ideal conditions (known as stoichiometry). The throttle position sensor tells the ECU how far the throttle plate is opened when you press the accelerator. The mass airflow sensor measures the amount of air flowing into the engine through the throttle plate. The engine coolant temperature sensor measures whether the engine is warm or cold. If the engine is still cool, additional fuel will be injected.
The carburetor car air fuel mix control is designed on the same principle, but the control of the solenoid mix or stepper motor is inserted in the carburetor float bowl.
Idle speed control
Most machine systems have idle speed controls built into the ECU. RPM engines are monitored by crankshaft positioning sensors that play a major role in engine timing functions for fuel injectors, spark events, and valve timings. Idle speed is controlled by programmable stop throttle or step bypass motors control air drainage. The early carburetor-based system used a programmable stop throttle using a two-way DC motor. Initial throttle body injection system (TBI) uses an inactive air stepper control motor. Effective idle speed control should anticipate the load of the engine when idle.
The full authority throttle control system can be used to control idle speed, providing cruise control functionality and the highest speed restrictions. It also monitors the ECU section for reliability.
Variable valve timing control
Some machines have Variable Valve Timing. In such machines, the ECU controls the time in the engine cycle where the valve is open. Valves usually open faster at higher speeds than at lower speeds. This can increase airflow into the cylinder, increase power and fuel savings.
Electronic valve control
Experimental machines have been manufactured and tested that do not have a camshaft, but have full electronic control from the opening of the inlet and exhaust valves, valve closure and valve opening area. Such machines can be started and run without starter motors for certain multi-cylinder engines equipped with precision electronic ignition and fuel injection. Such a static-start engine will provide increased efficiency and increased pollution reduction from lightweight hybrid electric propulsion, but without the cost and complexity of a large starter motor.
The first production machine of this type was created (in 2002) and introduced (in 2009) by Italian car maker Fiat at Alfa Romeo MiTo. Their Multiair machines use electronic valve controls that dramatically increase torque and horsepower, while reducing fuel consumption by as much as 15%. Basically, the valve is opened by a hydraulic pump, operated by the ECU. The valve can open several times per intake stroke, based on machine load. The ECU then decides how much fuel should be injected to optimize combustion.
Under stable load conditions, the valve is open, fuel is injected, and the valve closes. Under a sudden throttle increase, the valve opens in the same intake step and larger amounts of fuel are injected. This allows direct acceleration. For the next stroke, the ECU calculates the engine load on the new higher RPM, and decides how to open the valve: start or end, wide open or half open. The opening and optimal time are always achieved and burning is as precise as possible. This, of course, is not possible with a normal camshaft, which opens the valve for the entire period of intake, and is always fully lifted.
Removal of cams, lifter, rocker, and timing sets not only reduce weight and bulk, but also friction. Most of the power generated by the engine is actually used simply by moving the valve train, compressing all valve springs a thousand times every minute.
Once more developed, electronic valve operation will generate more benefits. Cylinder deactivation, for example, can be made much more fuel efficient if the intake valve can be opened at any downstroke and the exhaust valve is opened at each upstroke of the disabled cylinder or "dead hole". Another more significant advance is the conventional throttle removal. When a car is run in the throttle, the interruption in the airflow causes an excessive vacuum, which causes the machine to use valuable energy that acts as a vacuum pump. BMW is trying to get around this on their powered V5-M5, which has individual throttle butterflies for each cylinder, placed just before the intake valve. With an electronic valve operation, it will be possible to control engine speed by adjusting the valve lift. In the throttle section, when less air and gas is needed, the valve lift will not be that big. The full throttle is reached when the gas pedal is pressed, sends an electronic signal to the ECU, which in turn governs the lifting of each valve event, and opens it all.
Maps Engine control unit
Programmable
The special category of ECU is programmable. These units have no fixed behavior and can be reprogrammed by the user.
Programmable ECUs are required if significant aftermarket modifications have been made to the vehicle engine. Examples include adding or changing turbochargers, adding or replacing intercoolers, changing the exhaust system or conversion to run on alternative fuels. As a consequence of this change, the old ECU may not provide appropriate controls for the new configuration. In this situation, a programmable ECU can be connected. These can be programmed/mapped with laptops connected via a serial or USB cable, while the machine is running.
A programmable ECU can control the amount of fuel to be injected into each cylinder. This varies depending on the engine's RPM and the accelerator pedal position (or manifold air pressure). The tuner engine can adjust this by bringing up a page like a spreadsheet on a laptop where each cell represents an intersection between a certain RPM value and the position of the gas pedal (or throttle position, as it is called). In this cell, the number corresponding to the amount of fuel to be injected is entered. This worksheet is often referred to as a fuel table or fuel map.
By modifying these values ​​while monitoring the exhaust using a wide lambda probe to see if the engine is running rich or lean, the tuner can find the optimal amount of fuel to inject into the engine on each combination of RPM and different throttle positions. This process is often done on a dynamometer, giving the tuner a controlled environment to work. A dynamometer of the engine provides a more precise calibration for racing applications. Tuners often use chassis dynamometers for roads and other high performance applications.
Other parameters that can often be solved are:
- Ignition Time: Defines at which point in the machine cycle, the spark plug should be lit for each cylinder. Modern systems allow for individual trim on each cylinder for optimization per cylinder of ignition timing.
- Pdt. limit: Defines the maximum RPM allowed to be reached by machine. After this fuel and/or ignition is cut. Some vehicles have a "soft" termination before a "hard" cut-off. This "soft cut" generally works by slowing the ignition timing to reduce the power output and thus slow the acceleration rate just before the "hard cut" is hit.
- Water temperature correction: Allows for additional fuel to be added when the engine is cold, as in cold-start winter scenario or when the engine is very hot, to allow additional cylinder cooling (though not by way of which is very efficient, as an emergency only).
- Temporary charging: Notifying E.C.U. to add a certain amount of fuel when the throttle is applied. This is called "acceleration enrichment".
- Low fuel pressure converter: Tells the ECU to increase the injector spraying time to compensate for the increase or loss of fuel pressure.
- Closed loop lambda: Allows E.C.U. monitor lambda probes that are permanently installed and modify refueling to achieve the desired air/fuel ratio. This is often the ratio of stoichiometric air fuel (ideal), which is on a traditional gasoline-powered vehicle (gasoline), air ratio: this fuel is 14.7: 1. It can also be a much richer ratio for when the engine is under high loads, or perhaps a slimmer ratio for when the engine operates under low cruise load conditions for maximum fuel efficiency.
Some advanced ECU/advanced races include functionality such as launch controls, operate as a rev barrier when the car is in the starting line to keep the engine at a 'sweet spot', waiting for the clutch to be released to launch the car as quickly and efficiently as possible. Other examples of advanced functions are:
- Waste gate control: Controls turbocharger waste gate behavior, controlling drive. These can be mapped to order a specific duty cycle on the valve, or can use P.I.D. based on closed-loop control algorithm.
- Gradual injections: Allows for additional injectors per cylinder, used to obtain better fuel injection control and atomization through R.P.M. distance. An example is the use of small injectors for smooth and low idle conditions, and a larger set of larger injectors that are 'staged' at higher loads, such as when the turbo drive rises above the set point.
- Variable cam timing: Allows for control of intake variables and exhaust cams (VV.T), maps the exact forward/reverse camshafts curve for maximum benefit in all loading positions/rpm on the map. This function is often used to optimize power output at high load/R.P.M.s, and to maximize fuel efficiency and emissions as low load/R.P.M.s
- Gear controls: Tells the ECU to cut the ignition key during (successive gearboxes) up shift or blip throttle during downshifts.
- Anti-lag: Is an option provided by E.C.U.s racing only for turbo-charged vehicles. When it is on, it changes the ignition timing to the end, providing a quick charge from the turbocharger. When the anti-lag is active, gunshots and flames come from the exhaust, indicating extreme temperatures and pressures.
ECU races are often equipped with a data recorder that records all the sensors for later analysis using special software on the PC. This can be useful for tracking machine stalls, shootouts or other unwanted behavior during a race by downloading log data and looking for anomalies after the event. Data logger usually has a capacity between 0.5 and 16 megabytes.
To communicate with drivers, ECU races can often be connected to a "stack of data", which is a simple dashboard that presents drivers with current RPM, speed and other machine-base data. These races, almost always digital, speak with the ECU using one of several proprietary protocols running RS232 or CANbus, connecting to a DLC (Data Link Connector) usually located at the bottom of the dashboard, parallel to the steering wheel.
Sensors and actuators
Sensors for air flow, Pressure, Temperature, Speed, Oxygen Exhaust, Knock and Crank angle positioning sensors make a very important impact in EEMS .
History
Initial design
One of the earliest attempts to use integrated and automated devices to manage multiple control functions simultaneously was "KommandogerÃÆ'¤t" made by BMW in 1939, for their radial 801 14 cylinder radial flight machine. This device replaces the 6 controls used to start a hard acceleration with one control on an 801-series aircraft. However, it has some problems: it will soar the engine, making fly formations near Fw 190 (Focke-Wulf Fw 190 Wurger), an aircraft single German single-engine fighter, rather difficult, and at first it shifted the gross and random supercharger gears, which could throw the aircraft into a very dangerous place.
Hybrid digital design
Popular digital or analog hybrid designs in the mid-1980s. It uses analog techniques to measure and process input parameters from a machine, then use a lookup table stored in a digital ROM chip to generate computed result values. The system then calculates this output dynamically. The ROM type of the system can be set if someone knows the system well. The disadvantage of such a system is that precomputed values ​​are only optimal for the ideal new machine. As used by machines, systems are less able to compensate than CPU-based systems.
Modern design
Modern ECUs use microprocessors that can process inputs from machine sensors in real-time. The electronic control unit contains hardware and software (firmware). The hardware consists of electronic components on printed circuit boards (PCBs), ceramic substrate or thin laminate substrate. The main component of this circuit board is the microcomputer chip (CPU). This software is stored in microcontroller or other chip on P.C.B., usually in EPROM or flash memory so that C.P.U. can be reprogrammed by uploading updated codes or replacing chips. This is also referred to as the Machine Management System (electronic) (EMS).
Sophisticated engine management systems receive input from other sources, and control other parts of the machine; for example, some variable valve timing systems are electronically controlled, and turbocharger waste gates can also be managed. They can also communicate with transmission control units or directly electronically controlled electronic transmission interfaces, traction control systems, and the like. The Controller Area Network or CAN automotive bus network is often used to achieve communication between these devices.
Modern ECUs sometimes include features such as cruise control, transmission control, anti-skid brake control, and anti-theft controls, etc.
General Motors' (GM) The first ECU had a small application of hybrid digital ECU as a pilot program in 1979, but in 1980, all programs actively used a microprocessor-based system. Due to the large increase in ECU volume produced to meet the Clean Air Act requirements of 1981, only one ECU model can be built for the 1981 model. E.C.U. high volume installed in G.M. vehicles from the first year of high volume, 1981, and so on are modern microprocessor-based systems. GM is moving quickly to replace carburation with fuel injection as the preferred fuel delivery method for manufactured vehicles. This process first resulted in 1980 with fuel injected into the Cadillac engine, followed by the 2.5 "I" Iron Duke "Pontiac and Chevrolet 5.7L V8 L83" Cross-Fire "that propelled the Chevrolet Corvette in 1982. The 1990 Cadillac Brougham powered by the 5.0L V8 LV2 Oldsmobile engine is the last carburetor passenger car manufactured for sale in the North American market (the 1992 Volkswagen Beetle model powered by a carburetor engine is available for purchase in Mexico but not offered for sale in the United States or Canada) and on in 1991 GM was the last of the major US and Japanese manufacturers to abandon carburization and produce all passenger cars exclusively with fuel injection engines. In 1988 Delco (GM's electronics division), has produced more than 28,000 EC.U.s per day, making it the largest on-board digital control computer manufacturer in the world at the time.
Other apps
Such systems are used for many internal combustion engines in other applications. In aeronautical applications, this system is known as "FADEC" (Full Control Digital Sports Machine). Such electronic controls are less commonly used on fixed-wing aircraft and fixed-wing helicopters than in cars. This is due to the general configuration of the carburetor engine with a magneto ignition system that does not require the electrical power generated by the alternator to run, which is considered a safety advantage.
See also
- Throttle position sensor
- Engine coolant temperature sensor
- Airflow gauge
- Air-fuel ratio gauge
- Sensor crankshaft position
- Self starter car
- The electronic control unit (ECU), a generic term for any embedded system - is not to be confused with the engine control unit is also abbreviated, ECU
- Machine tapped
- Electronic engine management system
- Fuel injection
- Malfunction indicator light (MIL)
- Motronic
- On-board diagnostics (OBD)
- Powertrain control module (PCM)
- ECU-TEST
- Trionist
- Time removes the eliminator (TRE)
- FADEC (authoritative digital control machine)
- SECU-3
- MegaSquirt
- VEMS
References
External links
- How the Car Computer works
- Toyota OBDII ECU
- Machine Control System
- Articles from Toyota Motor Sales, USA, Inc. on Autoshop 101
- SECU-3 Ignition and fuel injection control unit
Source of the article : Wikipedia
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