Вопросы связанные с настройкой.
- Автор темы Monster
- Дата начала
В вопросу о корреляции и знающих людях 
It's not theoretical, but real. According to SAE International SAE J1979 / ISO 15031-5 (dated: 2014-08-11), calculated engine load is calculated by the following equation:
LOAD_PCT = [current airflow] / [(peak airflow at WOT@STP as a function of rpm) *
(BARO/29.92) * SQRT(298/(AAT+273))]
Where:
- STP = Standard Temperature and Pressure = 25 °C, 29.92 in Hg BARO,
- SQRT = square root
- WOT = wide open throttle
- AAT = Ambient Air Temperature (in °C)
Characteristics of LOAD_PCT are:
- Reaches 1.0 at WOT at any altitude, temperature or rpm for both naturally
aspirated and boosted engines.
- Indicates percent of peak available torque.
- Linearly correlated with engine vacuum
- Often used to schedule power enrichment.
- Compression ignition engines (diesels) shall support this PID using fuel
flow in place of airflow for the above calculations.
The second part of this portion (Characteristics) gives you a lot of the information you are seeking. The percentage given by the equation indicates percent of peak available torque.
There isn't a single sensor it uses to figure this out. For a gasoline (or spark ignition) engine, it utilizes the Air Intake Sensor (IAT), Manifold Absolute Pressure (MAP) sensor, Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) sensor to do calculations and to discover if the engine is at the ready point to make the calculations. The percentage variable can be read from the ECU using PID $04. According the the standard, both compression ignition (diesel) and spark ignition (gasoline) systems are required to maintain this.
You've seen the above equation for calculated engine load. Below is the calculation for absolute engine load:
LOAD_ABS = [air mass (g / intake stroke)] / [1.184 (g / intake stroke) *
cylinder displacement in liters]
Derivation:
- air mass (g / intake stroke) = [total engine air mass (g/sec)] /
[rpm (revs/min)* (1 min / 60 sec) * (1/2 # of cylinders (strokes / rev)]
- LOAD_ABS = [air mass (g)/intake stroke] / [maximum air mass (g)/intake
stroke at WOT@STP at 100% volumetric efficiency] * 100%.
Where:
- STP = Standard Temperature and Pressure = 25 °C, 29.92 in Hg (101.3 kPa)
BARO
- WOT = wide open throttle
The quantity (maximum air mass (g)/intake stroke at WOT@STP at 100%
volumetric efficiency) is a constant for a given cylinder swept volume.
The constant is 1.184 (g/liter 3) * cylinder displacement (liter 3/intake
stroke) based on air density at STP.
Characteristics of LOAD_ABS are:
- Ranges from 0 to approximately 0.95 for naturally aspirated engines,
0 – 4 for boosted engines
- Linearly correlated with engine indicated and brake torque,
- Often used to schedule spark and EGR rates,
- Peak value of LOAD_ABS correlates with volumetric efficiency at WOT.
- Indicates the pumping efficiency of the engine for diagnostic purposes.
As you can probably see, this equation relies on the flow of air and basically engine displacement. As it states in the body, this correlates with volumetric efficiency (how completely a cylinder fills with air on the intake stroke) at WOT. This variable can be read from the ECU on PID $43. It is only required by the standard on spark ignition systems.
It's not theoretical, but real. According to SAE International SAE J1979 / ISO 15031-5 (dated: 2014-08-11), calculated engine load is calculated by the following equation:
LOAD_PCT = [current airflow] / [(peak airflow at WOT@STP as a function of rpm) *
(BARO/29.92) * SQRT(298/(AAT+273))]
Where:
- STP = Standard Temperature and Pressure = 25 °C, 29.92 in Hg BARO,
- SQRT = square root
- WOT = wide open throttle
- AAT = Ambient Air Temperature (in °C)
Characteristics of LOAD_PCT are:
- Reaches 1.0 at WOT at any altitude, temperature or rpm for both naturally
aspirated and boosted engines.
- Indicates percent of peak available torque.
- Linearly correlated with engine vacuum
- Often used to schedule power enrichment.
- Compression ignition engines (diesels) shall support this PID using fuel
flow in place of airflow for the above calculations.
The second part of this portion (Characteristics) gives you a lot of the information you are seeking. The percentage given by the equation indicates percent of peak available torque.
There isn't a single sensor it uses to figure this out. For a gasoline (or spark ignition) engine, it utilizes the Air Intake Sensor (IAT), Manifold Absolute Pressure (MAP) sensor, Throttle Position Sensor (TPS), and Engine Coolant Temperature (ECT) sensor to do calculations and to discover if the engine is at the ready point to make the calculations. The percentage variable can be read from the ECU using PID $04. According the the standard, both compression ignition (diesel) and spark ignition (gasoline) systems are required to maintain this.
You've seen the above equation for calculated engine load. Below is the calculation for absolute engine load:
LOAD_ABS = [air mass (g / intake stroke)] / [1.184 (g / intake stroke) *
cylinder displacement in liters]
Derivation:
- air mass (g / intake stroke) = [total engine air mass (g/sec)] /
[rpm (revs/min)* (1 min / 60 sec) * (1/2 # of cylinders (strokes / rev)]
- LOAD_ABS = [air mass (g)/intake stroke] / [maximum air mass (g)/intake
stroke at WOT@STP at 100% volumetric efficiency] * 100%.
Where:
- STP = Standard Temperature and Pressure = 25 °C, 29.92 in Hg (101.3 kPa)
BARO
- WOT = wide open throttle
The quantity (maximum air mass (g)/intake stroke at WOT@STP at 100%
volumetric efficiency) is a constant for a given cylinder swept volume.
The constant is 1.184 (g/liter 3) * cylinder displacement (liter 3/intake
stroke) based on air density at STP.
Characteristics of LOAD_ABS are:
- Ranges from 0 to approximately 0.95 for naturally aspirated engines,
0 – 4 for boosted engines
- Linearly correlated with engine indicated and brake torque,
- Often used to schedule spark and EGR rates,
- Peak value of LOAD_ABS correlates with volumetric efficiency at WOT.
- Indicates the pumping efficiency of the engine for diagnostic purposes.
As you can probably see, this equation relies on the flow of air and basically engine displacement. As it states in the body, this correlates with volumetric efficiency (how completely a cylinder fills with air on the intake stroke) at WOT. This variable can be read from the ECU on PID $43. It is only required by the standard on spark ignition systems.
... Продолжаю, потому что тишина
В выше приведенном частном случае load = 100
Как ещё может получится load = 100? На избытке в ресивере и коэффициенте наполнения меньше 1, или когда на неполном дросселе давление в ресивере меньше атмосферного, но у нас настолько ахриненный мотор, что коэффициент наполнения >1 ... Т.е. это всё частные случаи.
А так, да, весь этот load просто отражает наполнение цилиндров, как в 5х январях на стоковых прошивках карты уоз и смеси привязаны к наполнению, и если бы вместо абсолютного наполнения был коэффициент наполнения относительно максимально возможного, то мы бы имели в стоке подобные load в качестве оси.
В выше приведенном частном случае load = 100
Как ещё может получится load = 100? На избытке в ресивере и коэффициенте наполнения меньше 1, или когда на неполном дросселе давление в ресивере меньше атмосферного, но у нас настолько ахриненный мотор, что коэффициент наполнения >1 ... Т.е. это всё частные случаи.
А так, да, весь этот load просто отражает наполнение цилиндров, как в 5х январях на стоковых прошивках карты уоз и смеси привязаны к наполнению, и если бы вместо абсолютного наполнения был коэффициент наполнения относительно максимально возможного, то мы бы имели в стоке подобные load в качестве оси.