Physically based charge-temperature model

Abstract

A physically based charge temperature model (10) for calculating a charge air temperature for a motor vehicle (12), comprising: several variables, including: one engine speed (70); a cam position (72); and an ignition component of an engine (14); and a controller (22) that controls the operation of the motor (12) and uses several variables, to calculate a charge air temperature (64) for individual intake strokes of at least one cylinder (16) of an engine (12) of a motor vehicle (12), wherein the engine speed (70) and the cam position (72) are entered into a lookup table to determine a quantity of heated cylinder gas mixture.

Description

[0001] The present disclosure relates to the prediction of the charge air temperature of a motor vehicle engine.

[0002] Automotive engines can be controlled using an estimated intake air temperature and a measured mass of air entering a cylinder to calculate the amount of fuel to be supplied for each intake stroke and to adjust the engine management system. Since direct temperature measurement in the combustion chamber is not possible, the intake air temperature is estimated using algorithms. Current algorithms for estimating the intake air temperature are based on variables such as the intake air temperature, the engine's air mass flow rate, the vehicle speed, and the coolant temperature, which is used to estimate the heat transferred to the intake air volume.It has been found that vehicle speed has only a minimal influence on the airflow through the engine compartment in newer, aerodynamically designed vehicles, as this is partly due to the increased size of the engine and its components within the available space, as well as the use of air flaps in the engine compartment. Therefore, the airflow through the engine compartment does not vary significantly with vehicle speed.

[0003] Furthermore, current algorithms do not accurately account for the exhaust gas mixture present at the engine's intake ports, which can increase the average charge air temperature. Current algorithms also fail to accurately account for multiple different engine operating states, including cylinder deactivation events or camshaft position changes available with variable valve timing.

[0004] While current algorithms for estimating charge air temperature in motor vehicles fulfill their purpose, there is therefore a need for a new and improved system and method for estimating charge air temperature.

[0005] US 2008 / 0066715A1 describes a method for operating an engine with at least one cylinder during homogeneous compression ignition. The method includes: directing a first airflow to the cylinder through a first throttle valve; directing a second, separate airflow to the cylinder through a second throttle valve, the first flow having a higher temperature than the second airflow; regulating a total airflow of a mixture of the first and second flows to a desired value by varying the openings of the first and second throttle valves in the same direction; and adjusting the combustion timing during compression ignition by increasing the opening of one throttle valve and decreasing the opening of the other throttle valve.

[0006] DE 10 2012 212 479 A1 describes an engine with an intake manifold that mixes an intake air flow and an exhaust gas recirculation flow to provide an intake charge flow. A method for estimating an intake charge temperature includes monitoring system conditions for the engine, determining the effect of the mixing on a specific heat coefficient of the intake charge flow based on the monitored system conditions, estimating an intake charge temperature based on the effect of the mixing on the specific heat coefficient of the intake charge flow and based on the monitored system conditions, and controlling the engine based on the estimated intake charge temperature.

[0007] US Patent 6,286,366 B1 describes a technique for determining the intake air temperature of a vehicle's internal combustion engine without using a dedicated temperature sensor. The technique involves identifying a nonlinear dynamic model based on the physical concepts of heat transfer and system identification techniques. The intake air temperature model utilizes several available physical measurements from the vehicle, including intake air temperature, engine coolant temperature, vehicle speed, manifold pressure, engine speed, exhaust gas recirculation (EGR) status, and the on / off state of the engine fan. The model parameters are determined based on specific vehicle characteristics and collected data from the vehicle. The intake air temperature is predicted by the model at regular, predetermined intervals based on the physical measurements, the vehicle parameters, and the intake air temperature at the previous time point.An estimate of the initial charge air temperature at vehicle start-up can be made using the available temperature sensor values ​​at vehicle start-up, the stored charge air temperature data, and any temperature values ​​measured immediately before the engine is switched off. DESCRIPTION

[0008] According to the invention, a physically based charge air temperature model for calculating a charge air temperature for a motor vehicle comprises several variables, including: an engine speed; a cam position; and an engine firing rate. A controller manages the engine operation and uses the several variables to calculate a charge air temperature for individual intake strokes of at least one cylinder of a motor vehicle engine. The engine speed and cam position are entered into a lookup table to determine the quantity of heated cylinder gas mixture.

[0009] In another aspect of the present disclosure, the multiple variables include an engine coolant temperature measured by a coolant temperature sensor.

[0010] In another aspect of the present disclosure, the multiple variables include an air inlet temperature measured by a temperature sensor at an inlet to a cylinder inlet line.

[0011] In another aspect of the present disclosure, the multiple variables include an engine airflow measured in grams per second using a mass airflow (MAF) sensor.

[0012] In another aspect of the present disclosure, the at least one cylinder comprises several cylinders, and wherein the ignition fraction of the engine defines an average quantity of the several cylinders that fire during individual engine cycles.

[0013] In another aspect of the present disclosure, a total connection flow rate is determined, which is equal to the engine airflow divided by the ignition fraction.

[0014] In another aspect of the present disclosure, the engine coolant temperature and the air inlet temperature are used to determine a delta coolant charge, wherein the delta coolant charge is equal to the engine coolant temperature minus the air inlet temperature.

[0015] In another aspect of the present disclosure, the multiple variables include an air inlet temperature measured by a temperature sensor at an outlet of an intercooler.

[0016] In another aspect of the present disclosure, an output from the lookup table defines a cylinder gas influence (CGI), wherein, if engine scavenging is present, the CGI is set to one (1), otherwise a value of the CGI is determined from the lookup table.

[0017] From several perspectives, a physically based charge air temperature model for calculating a motor vehicle's charge air temperature includes multiple variables. A first variable defines the engine speed, which specifies the revolutions per minute of the engine's crankshaft. A second variable defines the camshaft position relative to the crankshaft position. A third variable defines the engine coolant temperature. A fourth variable defines the air intake temperature. A fifth variable defines the engine airflow. A sixth variable defines the engine's firing rate. A control unit has several lookup tables. The control unit manages the engine's operation and uses the multiple variables and data in these lookup tables to calculate the charge air temperature for individual intake strokes of at least one engine cylinder.

[0018] In another aspect of the present disclosure, the control system uses the ignition component to estimate an airflow that is used to determine heat transfer from the engine.

[0019] In another aspect of the present disclosure, the engine speed and cam position, when entered into a first of several lookup tables, identify whether there is a backflow of engine cylinder gas into an intake line and affects the heat transferred into the intake line, which in turn affects the intake air temperature.

[0020] In another aspect of the present disclosure, a delta temperature influence is derived from a second of the several reference tables.

[0021] In another aspect of the present disclosure, the delta temperature influence defines the heat that is individually transferred from an engine coolant, based on the engine coolant temperature, from an intake air volume, which is influenced by the intake air temperature, from the engine, which is influenced by the engine airflow, and from the ignition component to a charge air volume.

[0022] In another aspect of the present disclosure, a delta coolant charge is defined by the engine coolant temperature and the air intake temperature.

[0023] In another aspect of the present disclosure, the delta coolant charge is equal to the engine coolant temperature minus the air intake temperature.

[0024] According to several aspects, a procedure for operating a physically based charge temperature model to calculate a charge air temperature for a motor vehicle involves: obtaining several variables, including: measuring a first variable that defines an engine speed, which defines revolutions per minute of an engine's crankshaft; identifying a cam position as a second variable; capturing an engine coolant temperature as a third variable; defining an air intake temperature, provided by a temperature sensor, as a fourth variable; receiving data from an air mass flow sensor, which identifies an engine airflow, as a fifth variable; and determining an engine firing rate as a sixth variable.and controlling the operation of the engine using a controller with multiple lookup tables, wherein the controller applies the multiple variables and data in the multiple lookup tables and calculates a charge air temperature for individual intake strokes of at least one cylinder of the engine.

[0025] In another aspect of the present disclosure, the method further includes the calculation of a delta coolant charge which is equal to the engine coolant temperature minus the air inlet temperature.

[0026] In another aspect of the present disclosure, the method further comprises: inputting the engine speed and cam position into a first of several lookup tables to determine whether there is an engine cylinder backflow into an intake manifold condition and whether this influences the heat transfer to the air intake temperature; and deriving a delta temperature influence from a second of several lookup tables.

[0027] Further areas of application will become apparent from the description presented here. It goes without saying that the description and specific examples serve only for illustration and are not intended to limit the scope of this disclosure. BRIEF DESCRIPTION OF THE FIGURES

[0028] The figures described here serve only for illustration and are not intended to limit the scope of the present revelation in any way. Fig. Figure 1 is a schematic representation of a physically based charge temperature model for use in a motor vehicle according to an exemplary aspect; Fig. Figure 2 is a cross-sectional view from above, taken in section 2 of Fig. 1; and Fig. Figure 3 is a flowchart of process steps for using the physically based charge temperature model of Fig. 1 DETAILED DESCRIPTION

[0029] The following description is merely exemplary and is not intended to limit the present disclosure, application or use.

[0030] Referring to Fig. Figure 1 is a physically based charge temperature system and operating procedure, hereinafter referred to as the physically based charge temperature model 10, provided in a motor vehicle 12. The motor vehicle 12 comprises an engine 14 with multiple cylinders 16. In the example shown, eight cylinders 16 are depicted; however, the engine 14 can have any number of cylinders 16, including but not limited to 2, 4, 6, 8, or 10 cylinders. Each cylinder 16 comprises at least one inlet valve 18 that directs the charge air into the cylinder 16 and at least one exhaust valve 20 that directs the exhaust gases from the cylinder 16 to the outside. The engine operation is controlled by at least one controller or processor, hereinafter referred to as the powertrain or engine controller 22.The controller 22 can be any type of device capable of processing electronic instructions, including microprocessors, microcontrollers, host processors, vehicle communication processors, and application-specific integrated circuits (ASICs).

[0031] The control unit 22 can be a dedicated controller or processor used for engine control, or it can be used in conjunction with other vehicle systems. The control unit 22 executes various types of digitally stored instructions, such as software, lookup tables, or firmware programs, which are stored in a memory 24 that can hold multiple pre-filled lookup tables. These instructions enable the control unit 22 to provide a variety of services. For example, the control unit 22 can execute programs and process data to perform at least part of the procedure described herein, and it can communicate with other devices, such as a transmission control unit 26, and control an engine output torque. At least one camshaft 28 is also provided to actuate the at least one inlet valve 18 and the at least one exhaust valve 20.

[0032] In the schematic representation of Fig. In Section 1, the engine 14 is defined as an internal combustion engine with fuel injectors 30 that control the flow of fuel and spark plugs 32 that are controlled by the engine control unit 22. The engine 14 includes a crankshaft 34, the speed and position of which are detected by a speed and position detector 36, which generates a signal, such as a pulse train, for the engine control unit 22. The engine 14 can be a gasoline internal combustion engine or any other internal combustion engine known in engineering. An intake manifold 38 supplies air to the cylinders 16.The at least one intake valve 18 and the at least one exhaust valve 20 are coupled to the camshaft 28 and can be used in an overhead valve or overhead cam configuration. These valves can be physically coupled and decoupled from the at least one intake valve 18 and the at least one exhaust valve 20 to shut off the air and fuel flow through the cylinders 16. An airflow sensor 40 and a manifold absolute pressure (MAP) sensor 42 can be used to detect airflow in an intake duct and air pressure within the intake manifold 38 and to generate signals to the engine control unit 22.

[0033] An electronic throttle 44 with a throttle plate controlled by an electronic throttle controller 46 can be used to receive signals from the engine control unit 22 to control the mass of air entering the intake manifold 38. The electronic throttle controller 46 can include a power circuit for modulating the electronic throttle valve 44 and a circuit for receiving position and speed setpoints from the electronic throttle valve 44. The electronic throttle controller 46 can also include a communication circuit, such as a serial connection or an automotive communication network interface, to communicate with a powertrain control unit (not shown) via an automotive communication network 48.

[0034] Depending on several aspects, the engine 14 can be a naturally aspirated engine, a turbocharged engine 50, or a supercharged engine with a compressor to increase the intake air pressure for the charge air supply. The compressor or turbocharger 50 can be connected to an intercooler 51 to pre-cool the increased charge air supply.

[0035] With reference to Fig. 2 and back again Fig. Figure 1 shows a single cylinder 16. The intake valve 18 directs charge air and fuel as a mixture via an intake manifold 52 into a combustion chamber 54 above a piston 56 in cylinder 16. Depending on the specific circumstances, the fuel can be injected directly into the combustion chamber 54, independent of the charge air. The exhaust valve 20 directs the exhaust gases out of cylinder 16 via an exhaust port 58. A spark plug 60, also controlled by the engine control unit 22, serves to improve the ignition timing of the engine 14 across a range of engine loads. The control of the movement of the intake valve 18 and the exhaust valve 20 is designed for a four-stroke cycle with a cam-operated valve system. In the figure, the exhaust valve 20 is open during the rotation of the crankshaft 34, thus defining one engine cycle.

[0036] During the first period of the opening or exhaust stroke, the intake valve 18 is closed, the exhaust valve 20 is open, and combusted gases are expelled from the combustion chamber 54 to the exhaust port 58. During the second period of the opening or intake stroke, the exhaust valve 20 is closed, the intake valve 18 is open, and a fuel / air mixture is drawn into the combustion chamber 54 through the intake port 52. During the third period, the intake valve 18 closes, and a compression stroke is executed. Ignition of the fuel / air mixture occurs after compression during the compression stroke. During the fourth period, the combustion of the fuel-air mixture leads to expansion of the gases in a power stroke. The four-stroke cycle then begins again.As is known, the timing of the opening and closing of the inlet valve 18 and the exhaust valve 20 can be varied to open or close earlier or later, as described below.

[0037] As already mentioned, the valve train is linked to the position of the engine 14, which is measured by the speed and position detector 36. The speed and position detector 36 is connected to the crankshaft 34, which is connected to the piston 56 via a connecting rod 62 to move the piston 56 back and forth in the cylinder 16.

[0038] With reference to Fig. 3 and again on Fig. 1 and Fig. The physically based charge air temperature model 10 provides an estimate of the charge air temperature 64 of a motor vehicle according to several aspects. The charge air temperature 64 is calculated by the engine control unit 22 and used by the engine control unit 22 to calculate a quantity of fuel 66 to be supplied to the intake manifold 52, together with an estimated charge air mass 68 for individual intake strokes of the cylinders 16. The physically based charge air temperature model 10 includes several variables. A first variable defines an engine speed 70, measured in engine crankshaft revolutions per minute (rpm). The engine speed 70 can be a temperature-corrected value. The engine speed 70 is used to estimate a volume of air that flows back from a cylinder 16 into the intake manifold 52, since this heated air volume preheats or influences the temperature of the intake or charge air that subsequently enters the cylinder 16.At lower engine speeds, e.g. below approximately 1400 rpm, the volume of the air return flow is increased compared to a volume of air return flow that occurs at higher engine speeds, e.g. above 1400 rpm, because at lower engine speeds more time is available for the charge air to pass through the system.

[0039] A second variable defines a cam position 72, which can be a cam position determined by a camshaft adjuster 74. A third variable defines an engine coolant temperature 76, which is measured, for example, by a coolant temperature sensor 78. The engine coolant temperature 76 determines a cylinder head temperature, which in turn influences the temperature of the air flowing through the cylinder head and thus determines the temperature of the intake manifold 52. The physically based charge temperature model 10 also considers engine start conditions in which the cylinder head is at or near atmospheric temperature before the engine heats up, and therefore the engine coolant temperature 76 is at or near atmospheric temperature.

[0040] A fourth variable of the physically based charge temperature model 10 defines an air inlet temperature 80, which is measured, for example, with a temperature sensor 82. The location where the intake air temperature 80 is determined can vary. For example, in a naturally aspirated engine, the air inlet temperature 80 can be measured at an inlet to the intake manifold 52, as shown in Fig. 2 described, are determined, whereby the air intake temperature 80 in a turbocharged or supercharged engine with the in Fig. The turbocharger 50 described in 1 can be determined at an outlet from the charge air cooler 51.

[0041] A fifth variable of the physically based charge temperature model 10 defines an engine airflow 84 or an air mass flow rate entering the engine intake manifold 38. The engine airflow 84 can be measured, for example, in grams per second using an air mass flow sensor 86, similar to the one described in Fig.1 described airflow sensor 40, which can be located near the intake pipe 52 in a naturally aspirated engine.

[0042] A sixth variable of the physically based charge temperature model 10 defines a firing ratio 88, which indicates an average number of cylinders 16 that fire during individual engine cycles. In an exemplary eight-cylinder engine, the firing ratio is 1.0 if all eight cylinders fire during each engine cycle, and 0.5 if only four of the eight cylinders fire. A value between 1.0 and 0.5 can therefore be applied if the average number of firing cylinders changes between 8 and 4 over two or more engine cycles.

[0043] The engine speed 70 and the cam position 72, which can define a camshaft adjustment degree, are used, after reference to a first lookup table 90, to identify a magnitude of the influence of the heated cylinder gas mixed into the intake manifold 52. Engine scavenging, or an engine scavenging condition, occurs primarily in supercharged or turbocharged engines due to the increased intake air pressure. In certain supercharged engines, the intake valve 18 and the exhaust valve 20 can open simultaneously, allowing air to flow through the combustion chamber 54 without combustion taking place. This process can purge unburned gas from a previous cycle, allowing a new, fresh quantity of charge air and fuel to be injected and burned, for example, to maximize a start with the throttle open.An output from the first lookup table 90 defines a value of a cylinder gas influence (CGI) 92, which can be applied as a Boolean value (zero or one). For example, if engine scavenging is present, a value of CGI 92 is set to one (1); otherwise, the value of CGI 92 remains at a value specified in the first lookup table 90.

[0044] The value of CGI 92 is one of several values ​​that are input into Algorithm 94. Algorithm 94 determines a steady-state charge air temperature and can be expressed in Equation 1 as follows: Charge temperature (degrees Kelvin) Faster state = (Delta [Δ] Coolant fill 96× Δ Temp. influence 98+Air Intake Temp 80)×(CGI)92

[0045] In equation 1 above, the Δ-coolant filling 96 is determined by equation 2 as follows: Δ Coolant fill 96 = Coolant temperature 76 − Air inlet temperature 80

[0046] The coolant charge Δ 96 determined above is one of four variables used to calculate the temperature influence Δ 98. The temperature influence Δ 98 is derived from a second lookup table and indicates how much heat is transferred to the charge air volume due to the engine coolant temperature 76, the intake air influenced by the intake air temperature 80, the engine air 14 influenced by the engine airflow 84, and as an effect of the ignition timing 88. The temperature influence Δ 98 is determined by inputting values ​​for the coolant charge Δ 96 and a total connection flow rate 100 into the second lookup table.

[0047] The total connection flow rate 100 is calculated using equation 3 as follows: Total connection flow rate 100 = Engine air flow rate 84 ÷ Ignition section 88

[0048] In parallel with the determination of the Δ-temperature influence 98, the total connection flow 100 calculated above is also entered into a third lookup table, which defines a lookup table 102 for the charge temperature filter. An output containing the steady-state charge air temperature and an output from the lookup table 102 of the charge temperature filter are fed into a first-order delay filter 104. A coefficient of the delay filter 104 can vary based on the engine air flow 84, which affects the output of the lookup table 102 of the charge temperature filter to change the value of the vehicle charge air temperature 64. The vehicle charge air temperature 64 is repeatedly calculated by the controller 22 during vehicle operation, for example, once every 100 milliseconds.

[0049] The physically based charge air temperature model 10 uses a physical model to predict the charge air temperature of a motor vehicle by: 1) using a difference between an engine coolant temperature and an intake air temperature as one of the inputs for a heat transfer coefficient; 2) multiplying a predicted airflow by an ignition fraction to obtain a suitable flow value that changes depending on how many cylinders are actively firing; 3) using the engine speed and an intake camshaft adjustment factor to determine the amount of backflow of hot cylinder gas present in an intake duct that affects the intake air temperature; 4) the physically based charge air temperature model 10 considers an effect of scavenging on the charge air temperature and exhaust gas recirculation;and 5) the physically based charge temperature model 10 applies the engine coolant temperature multiplied by a heat transfer coefficient as an offset to the intake air temperature (IAT).

[0050] A physically based charge temperature model 10 of the present disclosure offers several advantages. These include the use of an ignition component to determine a relevant airflow for an algorithm used in determining heat transfer from a manifold / port wall. The physically based charge temperature model 10 accounts for scavenging in turbocharged applications. The engine speed and the degree of intake camshaft adjustment are also used in tables to multiply a prediction of the base charge temperature, thereby enabling a calibrator to account for exhaust residues forced into the intake manifold during late intake valve closing (LIVC).

[0051] Base temperature increases are also applied as an offset to the IAT based on physical modeling.

[0052] The description of the present revelation is merely exemplary, and variations that do not deviate from the core of the present revelation are to be considered within the scope of the present revelation. Such variations are not to be considered a deviation from the spirit and scope of the present revelation.

Claims

[1] A physically based charge temperature model (10) for calculating a charge air temperature for a motor vehicle (12), comprising: several variables, including: one engine speed (70); a cam position (72); and an ignition component of an engine (14); and a controller (22) that controls the operation of the motor (12) and uses several variables, to calculate a charge air temperature (64) for individual intake strokes of at least one cylinder (16) of an engine (12) of a motor vehicle (12), wherein the engine speed (70) and the cam position (72) are entered into a lookup table to determine a quantity of heated cylinder gas mixture. [2] The physically based charge temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 1, wherein the multiple variables include an engine coolant temperature (76) which is measured using a coolant temperature sensor (78). [3] The physically based charge temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 2, wherein the multiple variables include an air inlet temperature (80) which is measured using a temperature sensor (82) at an inlet to a cylinder inlet line. [4] The physically based charge air temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 3, wherein the multiple variables include an engine airflow (84) measured in grams per second using a mass airflow sensor (86), MAF. [5] The physically based charge air temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 4, wherein the at least one cylinder (16) comprises several cylinders (16), and wherein the ignition fraction of the engine (12) defines an average number of the several cylinders (16) that ignite during individual engine cycles. [6] The physically based charge air temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 4, which further includes a total connection flow rate (100) which is equal to the engine air flow (84) divided by the ignition fraction. [7] The physically based charge temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 3, wherein the engine coolant temperature (76) and the air inlet temperature (80) are used to determine a delta coolant charge (96), wherein the delta coolant charge (96) is equal to the engine coolant temperature (76) minus the air inlet temperature (80). [8] The physically based charge temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 3, wherein the multiple variables include an air inlet temperature (80) which is measured using a temperature sensor (82) at an outlet of a charge air cooler (51). [9] The physically based charge temperature model (10) for calculating the charge air temperature (64) for the motor vehicle (12) according to claim 1, wherein an output from the lookup table defines a cylinder gas influence, CGI, and wherein, if engine scavenging is present, the CGI is set to one (1), otherwise a value of the CGI is determined from the lookup table.

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