manifold absolute pressure sensor ( PETA sensor ) is one of the sensors used in the internal combustion engine internal combustion control system.
Machines that use MAP sensors are usually injected fuel. The absolute manifold pressure sensor provides instantaneous manifold pressure information to the machine's electronic control unit (ECU). This data is used to calculate the air density and determine the air flow rate of the engine air, which in turn determines the fuel metering required for optimal combustion (see stoichiometry) and affects the progress or inhibition of ignition timing. Fuel injected engines may alternately use air flow sensors (MAF sensors) to detect incoming airflow. A commonly naturally aspirated engine configuration uses one or the other, while a forced induction machine usually uses both; MAF sensors on the pre-turbo intake channel and MAP sensor on the charge pipe leading to the throttle body.
MAP sensor data can be converted into air mass data using the speed-density method. Engine speed (RPM) and air temperature are also required to complete speed-density calculations. The MAP sensor can also be used in OBD II (on-board diagnostic) applications to test the EGR (exhaust gas recirculation) valves for functionality, typical applications in OBD II equipped with General Motors engines.
Video MAP sensor
Contoh
The following example assumes the same engine speed and air temperature.
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- Condition 1:
- A machine that operates on a wide open throttle (WOT) on a very high mountain has a manifold pressure of about 50 kPa (essentially the same as a barometer at high altitude).
- Condition 2:
- The same engine at sea level will reach 50 kPa (7.25 psi, 14.7 inHG) from manifold pressure less than WOT due to higher barometric pressure.
The engine needs the same fuel mass in both conditions because the air mass coming into the cylinder is the same.
If the throttle is opened all the way in condition 2, the absolute manifold pressure will increase from 50 kPa to nearly 100 kPa (14.5 psi, 29.53 inHG), almost equal to the local barometer, which in condition 2 is the sea level. The higher absolute pressure in the intake manifold increases the air density, and in turn more fuel can be burned resulting in higher output.
Another example is the range of rpm and engine load -
Where the machine may have a 60kPa manifold pressure at 1800 rpm in unloaded conditions, loading the load with the throttle opening will further turn the final manifold pressure to 100kPa, the engine will remain at 1800 rpm but the loading will require different sparks and fills. delivery.
Maps MAP sensor
Comparison of vacuum
The engine vacuum is the difference between the pressure on the intake manifold and ambient atmospheric pressure. The engine vacuum is a "gauge" pressure, since the gauge naturally measures the pressure difference, not the absolute pressure. The machine fundamentally responds to air masses, not vacuum, and absolute pressure is needed to calculate mass. The air mass entering the engine is directly proportional to the air density, which is proportional to the absolute pressure, and inversely proportional to the absolute temperature.
Note: The carburetor relies heavily on the volume of air and vacuum flow, and does not directly infer the mass. As a result, the carburetor is an accurate, but not accurate, fuel gauge. The carburetor is replaced by more accurate fuel measurement methods, such as fuel injections combined with air mass flow sensors (MAF).
EGR Testing
With OBD II standards, vehicle manufacturers are required to test the exhaust gas recirculation valve (EGR) for functionality during driving. Some manufacturers use MaP sensors to achieve this. In these vehicles, they have MAF sensors for their main load sensors. The MaP sensor is then used for rationality checks and to test the EGR valve. The way they do this is when the vehicle slowdown when there is a low absolute pressure in the intake manifold (ie, the high vacuum in the intake manifold relative to the outside air) the powertrain control module (PCM) will open the EGR. valve and then monitor the MaP sensor values. If the EGR is functioning properly, the absolute manifold pressure will increase when the exhaust gas enters.
General confusion with sensor and boost gauge
The MAP sensor measures absolute pressure. Improving sensors or gauges measures the amount of pressure above a set of absolute pressures. That sets the absolute pressure typically 100 kPa. This is usually referred to as a measuring pressure. Boost pressure relative to absolute pressure - as one increases or decreases, so does the other. This is a one-to-one relationship with offset of -100 kPa to increase pressure. Thus the MaP sensor will always read 100 kPa more than the driving sensors that measure the same conditions. The MaP sensor will never display a negative reading because it measures absolute pressure, where zero is the absence of total pressure. Vacuum is measured as negative pressure relative to normal atmospheric pressure. The Vacuum-Boost Sensor can display a negative reading, indicating a vacuum or suction (a lower pressure condition than the surrounding atmosphere). In a forced induction machine (supercharged or turbocharged), a negative impulse reading indicates that the engine pulls the air faster than provided, creating suction. This suction is caused by throttling in the ignition ignition engine and is not present in the diesel engine. This is often called vacuum pressure when referring to an internal combustion engine.
In short, most propulsion sensors will read 100 kPa less than that read by the MaP sensor. One can convert the drive to the MaP by adding 100 kPa. One can convert from MaP to boost by reducing 100 kPa.
References
External links
- MaP Sensor
Source of the article : Wikipedia
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