ESTIMATION OF CHARGE FLOW TEMPERATURE

Abstract

Engine air system (100) for estimating a charge flow temperature (212), comprising: a temperature sensor (110) at the outlet of a charge air cooler (108), which is designed to receive a first temperature signal (308; T CACO ) to provide; a temperature sensor (142) at the outlet of an exhaust gas recirculation system, which is designed to provide a second temperature signal (312; T ECRO ) to provide; and a control module (144) designed to receive the first temperature signal (308; T CACO ) and the second temperature signal (312; T EGRO ) to receive, wherein the control module (144) includes a charge flow temperature estimation module (152) configured to estimate the charge flow temperature (212) at an intake manifold temperature sensing position (118) based on a combination of the first temperature signal (308; T CACO) multiplied by an estimated fresh air content (318; f AIR ) and the second temperature signal (312; T EGRO ) multiplied by an exhaust gas recirculation component (216; f AGR ) to determine; where the first temperature signal (308; T CACO ) is corrected to account for a time delay between a temperature reading at a location of the temperature sensor (110) at the outlet of the charge air cooler (108) and the intake manifold temperature sensing position (118), and the second temperature signal (312; T EGRO ) is corrected to account for a time delay between a temperature reading at a location of the temperature sensor (142) at the exhaust gas recirculation outlet and the intake manifold temperature sensing position (118).

Description

AREA OF INVENTION

[0001] Exemplary embodiments of the invention relate to the estimation of the charge flow temperature for internal combustion engines and, in particular, the estimation of the charge flow temperature using temperature sensors at other locations. BACKGROUND

[0002] In an internal combustion engine, a mixture of air and fuel is delivered through an intake valve to the cylinders, where it is compressed and combusted. After combustion, the pistons force the exhaust gases from the cylinders into an exhaust system. To control an internal combustion engine efficiently, a number of sensors typically provide feedback to control engine system actuators. An engine control module receives inputs such as engine speed, flow rates, pressures, and temperatures from these sensors and controls the amount of fuel delivered to the engine, as well as the air intake and exhaust system actuators, in response to these inputs. Accurate inputs improve the engine control module's ability to reduce emissions and enhance the engine's fuel economy.

[0003] The complexity of engine control systems typically increases as engine system designers strive to improve durability, performance, and fuel economy, and reduce combustion noise, while meeting government-mandated emissions standards. Adding extra sensors to an engine system increases system cost and weight. Accordingly, it is desirable to eliminate one or more sensors and synthesize data based on available inputs and system parameters, allowing control algorithms to operate using a synthesized sensor input. This eliminates the system cost, weight, and maintenance requirements associated with one or more physical sensors.

[0004] The German patent application DE 10 2007 007 945 A1 discloses a method for adjusting an exhaust gas recirculation rate, in which a charge flow temperature at an intake manifold temperature sensing position is estimated by multiplying a temperature at the outlet of a charge air cooler with an estimated fresh air fraction, multiplying a temperature at the outlet of an exhaust gas recirculation system with an exhaust gas recirculation fraction, and adding the results.

[0005] In publication DE 102 42 234 A1, a method for determining an exhaust gas recirculation quantity is disclosed which estimates a charge flow temperature using models and corrects the estimate using a coolant temperature.

[0006] Document DE 102 29 620 A1 discloses a method for determining an exhaust gas recirculation quantity, in which basic values ​​of an internal combustion engine for a basic state without exhaust gas recirculation are determined and used in operation to determine the currently injected quantity of gas mixture, whereby pressure ratios and temperature ratios are used.

[0007] In the publication DE 199 63 358 A1, a method and a device for controlling an internal combustion engine are disclosed, wherein a model of an air system is used to describe the known system dynamics and to determine quantities of the air system that are difficult or impossible to measure.

[0008] Document DE 101 58 247 A1 discloses a method for controlling an internal combustion engine with exhaust gas recirculation, which uses a model for an exhaust tract of the internal combustion engine that describes the behavior of the exhaust tract before and after a turbine that is assigned to the internal combustion engine.

[0009] German patent application DE 101 62 970 A1 discloses a method and a device for determining the exhaust gas recirculation mass flow rate of an internal combustion engine, in which a combustion chamber pressure is measured, the density of the gas mixture supplied to the internal combustion engine is determined, and a supplied gas mass flow rate is derived from this. Using a fresh air temperature, a temperature of the supplied gas mixture, and an exhaust gas temperature, the exhaust gas recirculation rate can be determined.

[0010] The document DE 103 19 333 A1 discloses a system and method for influencing an intake gas temperature in the combustion chamber of an HCCI-capable internal combustion engine, in which a coolant control valve is provided to adjust the amount of coolant flowing through an exhaust gas cooler and thereby influence the intake gas temperature. SUMMARY OF THE INVENTION

[0011] In an exemplary embodiment of the invention, an engine air system for estimating a charge flow temperature comprises a temperature sensor at the outlet of an intercooler, configured to provide a first temperature signal, a temperature sensor at the outlet of an exhaust gas recirculation system, configured to provide a second temperature signal, and a control module configured to receive the first and second temperature signals. The control module includes a charge flow temperature estimation module configured to determine the estimated charge flow temperature at an intake manifold temperature sensing location based on a combination of the first temperature signal multiplied by an estimated fresh air fraction and the second temperature signal multiplied by an exhaust gas recirculation fraction.The first temperature signal is corrected to account for a time delay between a temperature reading at a location of the temperature sensor at the outlet of the charge air cooler and the intake manifold temperature sensing position, and the second temperature signal is corrected to account for a time delay between a temperature reading at a location of the temperature sensor at the outlet of the exhaust gas recirculation and the intake manifold temperature sensing position.

[0012] The foregoing features and advantages and other features and advantages of the invention will become readily apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other features, advantages, and details appear only as examples in the following detailed description of embodiments, the detailed description referring to the drawings in which: Fig. 1 is a schematic drawing of an exemplary engine air system; Fig. 2 a data flow diagram of a module for estimating a charge flow temperature of a control module of Fig. 1 is; Fig. 3 An exemplary process for determining an estimated mixing temperature using a mixing module in Fig. 2 is; and Fig. 4 An exemplary process for determining an estimated charge flow temperature using a temperature calibration and correction module of Fig. 2 is. DESCRIPTION OF THE EXECUTION FORMS

[0014] With reference to now Fig. Figure 1 is an exemplary embodiment directed towards an engine air system 100. The engine air system 100 is configured to receive intake air 102 through an intake air mass flow sensor 104 in order to determine the intake air mass of the engine air system 100. In one embodiment, the intake air mass flow sensor 104 can be either a vane flow meter or a hot-wire type intake air mass flow sensor; however, it is understood that other sensor types can also be used. The intake air 102 is compressed and heated by a compressor 106 and then cooled by an intercooler 108. The air temperature at an outlet of the intercooler 108 can be determined by a temperature sensor 110 at the outlet of the intercooler, which is configured between the intercooler 108 and a throttle valve 112. The throttle valve 112 controls an airflow to a mixing point 114.An intake manifold 116 is designed to receive a charge flow from the mixing point 114. An intake manifold temperature sensing position 118, at which a charge flow temperature is to be determined, is arranged between the intake manifold 116 and the mixing point 114.

[0015] At the in Fig. In the example shown, the intake manifold 116 contains a left intake manifold bank 120 and a right intake manifold bank 122; however, it is understood that the left intake manifold bank 120 and / or the right intake manifold bank 122 may be omitted in other embodiments, for example in an inline engine as opposed to a V-engine. After combustion, exhaust gas flows from a line 124 to an exhaust manifold 128. The exhaust gas flows from the exhaust manifold 128 to a variable geometry turbocharger 130 and exits as exhaust gas 134 through an exhaust pipe 132. Exhaust gas also flows from the exhaust manifold 128 through an exhaust gas recirculation (EGR) valve 136. The EGR valve 136 controls an exhaust gas flow that is further divided by an EGR cooler bypass valve 138 and an EGR cooler 140. Recirculated exhaust gas returns to the mixing point 114. An EGR outlet temperature sensor 142 is configured between the EGR cooler 140 and the mixing point 114.

[0016] A control module 144 contains a processor 146, a memory 148, and an input / output interface (I / O interface) 150. The processor 146 is designed to receive sensor inputs and drive outputs through the I / O interface 150. For example, the processor 146 can receive temperature signals from the temperature sensor 110 at the outlet of the charge air cooler and from the EGR outlet temperature sensor 142, and control the throttle valve 112 and the EGR valve 136 in addition to processing other I / O of the engine air system 100. The memory 148 can store executable instructions, control rules, and data for use by the processor 146.

[0017] In one embodiment, the control module 144 includes a module 152 for estimating a charge flow temperature, which is stored in the memory 148. Fig. As shown in Figure 1, and executed by processor 146, module 152 for estimating a charge flow temperature is specifically implemented in control module 144. Module 152 for estimating the charge flow temperature estimates a charge flow temperature at intake manifold temperature sensing position 118 based on temperature signals received from temperature sensor 110 at the charge air cooler outlet and from EGR outlet temperature sensor 142. The estimated charge flow temperature eliminates the need for a physical sensor that would otherwise be present at intake manifold temperature sensing position 118.

[0018] Fig. Figure 2 is an illustration of a data flow diagram that demonstrates various elements that go into control module 144 of Fig. 1 can be embedded to implement module 152 for estimating the charge flow temperature. Various embodiments of the engine air system 100 of Fig. 1 can contain any number of submodules embedded within module 152 for estimating the charge flow temperature. As can be seen, the in Fig. The two submodules shown can also be combined or further subdivided. Inputs to module 152 for estimating the charge flow temperature can be obtained from the engine air system 100. Fig. 1. are captured, received by other (not shown) control modules, or determined by other sub-modules or modules.

[0019] One embodiment of module 152 for estimating the charge flow temperature, which is described in Fig. Figure 2 shows a charge mass flow module 202 in conjunction with an EGR rate estimator module 204. The EGR rate estimator module 204 can provide an output to a module 206 for an estimated gas constant and a mixing module 208. The module 206 for an estimated gas constant can provide feedback to the charge mass flow module 202. Alternatively, the module 206 for an estimated gas constant can be omitted. The mixing module 208 is connected to a temperature calibration and correction module 210, which outputs an estimated charge flow temperature 212. The estimated charge flow temperature 212 is fed back to the charge mass flow module 202.

[0020] The charge mass flow module 202 can calculate an estimated charge mass flow 214 based on an engine speed, a volumetric efficiency, a previous value of the estimated charge flow temperature 212, and an intake manifold pressure from the intake manifold 116. Fig. 1. The EGR proportion estimation module 204 can determine an EGR proportion 216 based on the estimated charge mass flow 214 from the charge mass flow module 202, an air mass flow from the intake air mass flow sensor 104 from Fig. 1 and an EGR valve position of the EGR valve 136 of Fig. 1. The module 206 for an estimated gas constant can supply an estimated gas constant 218 to the charge mass flow module 202 based on the EGR fraction 216 from the EGR fraction estimator module 204. The mixing module 208 can determine an estimated mixture temperature 220 based on the temperature signals it receives from the temperature sensor 110 at the outlet of the charge air cooler and from the EGR outlet temperature sensor 142. Fig. 1 receives, and determines the EGR share 216 from the EGR share estimation module 204. The temperature calibration and correction module 210 can determine the estimated charge flow temperature 212 based on the air mass flow from the intake air mass flow sensor 104. Fig. 1, the estimated mixture temperature 220 from the mixing module 208, the estimated charge mass flow 214 from the charge mass flow module 202, an engine coolant temperature, a vehicle speed, a fan speed, the engine speed, the fuel flow and the EGR share 216 from the EGR share estimation module 204.

[0021] The estimated charge mass flow 214 can be calculated by the charge mass flow module 202 using a velocity-density equation. For example, the estimated charge mass flow 214 can be calculated as a product of the engine speed, the volumetric efficiency, and the intake manifold pressure, and further divided by a previous value of the estimated charge flow temperature 212 with appropriate unit conversions. The EGR rate estimator 204 can calculate the EGR rate 216 based on a multidimensional lookup table as a function of the estimated charge mass flow 214 from the charge mass flow module 202, the air mass flow from the intake air mass flow sensor 104, and the air mass flow from the intake air mass flow sensor 104. Fig. 1 and the EGR valve position of the EGR valve 136 of Fig. 1. The module 206 for an estimated gas constant can determine the estimated gas constant 218 based on a one-dimensional lookup table. The mixing module 208 can determine the estimated mixing temperature 220 according to a process as described in Fig. Figure 3 shows that the temperature calibration and correction module 210 can determine the estimated charge flow temperature 212 according to a process as described in Figure 3. Fig. 4 is shown.

[0022] With reference to Fig. Figure 3 is an exemplary embodiment of a process for implementing the mixing module 208 of Fig. Figure 2 illustrates this. In the illustrated embodiment, the mixing module 208 determines the estimated mixing temperature 220 as a baseline estimate of the charge flow temperature according to an energy balance equation: TMIX=TCACO×fAIR+TEGRO×fAGR, where: T MIX the estimated mixing temperature 220 of Fig. 2 is; T CACO a temperature signal from temperature sensor 110 at the outlet of the charge air cooler from Fig. 1 is; f AIR an estimated fresh air component that corresponds to the mixing point 114 of Fig. 1 reached, which is considered a to f AGR a complementary value can be estimated, such that f AIR = 1 - f AGR ; T EGRO a temperature signal from the EGR outlet temperature sensor 142 from Fig. 1 is; and f AGR the EGR share 216 of Fig. 2 is.

[0023] In Fig. 3. Temperature sensor expansion blocks 302 and 304 may be included to eliminate time delays between temperature readings at the locations of temperature sensor 110 at the charge air cooler outlet and the EGR outlet temperature sensor 142. Fig. 1 and a flow which the intake manifold temperature sensing position 118 of Fig. 1, to be taken into account. In one embodiment, the temperature sensor extension blocks 302 and 304 are implemented using leading / lagging transfer functions that can be adjusted based on one or more calibrated sensor time constants. Alternatively, the temperature sensor extension blocks 302 and 304 can be omitted if reduced accuracy at the estimated charge flow temperature 212 can be tolerated. In the example of Fig. 3. The temperature sensor extension block 302 receives a time constant 306 from the charge air cooler sensor and a first temperature signal 308 from the temperature sensor 110 at the outlet of the charge air cooler. Fig. 1. The temperature sensor extension block 304 receives a time constant 310 from the EGR sensor and a second temperature signal 312 from the EGR outlet temperature sensor 142. Fig. 1. It is understood that the first and second temperature signals 308 and 312 are connected to I / O interface 150. Fig. 1 can be received and from the control module 144 of Fig. 1 can be pre-processed into suitable technical units, such as grade C.

[0024] The output of temperature sensor expansion blocks 302 and 304 can be in degrees Celsius, and unit conversions to Kelvin may be required for consistent further processing. In the example of Fig. 3. The output of the temperature sensor extension block 302 is summed with a conversion constant 314, multiplied by an estimated fresh air fraction 318, and output to a summation block 320. The estimated fresh air fraction 318 can be defined as the difference between a fraction adjustment constant 316 and the EGR fraction 216. Fig. 2 are calculated. In one embodiment, the proportion adjustment constant 316 is equal to one. The output of the temperature sensor extension block 304 is summed with a conversion constant 322, with the EGR proportion 216 of Fig. The result is multiplied by 2 and output to summing block 320. If a further unit conversion to degrees Celsius is required, the estimated mixing temperature 220 can be calculated as the difference between the output of summing block 320 and a conversion constant 324. In one embodiment, the conversion constants 314, 322, and 324 all have values ​​of 273. Alternatively, the conversion constant 324 can be minus 273, so that the final operation of the mixing module 208 is a sum rather than a difference.

[0025] With reference to now Fig. Figure 4 is an exemplary embodiment of a process for implementing the temperature calibration and correction module 210 of Fig. Figure 2 illustrates this. In the illustrated embodiment, the temperature calibration and correction module 210 determines the estimated charge flow temperature 212 based on a number of corrections to adapt to fuel, speed, and coolant conditions. One or more of the corrections can be omitted if a reduced accuracy in the estimated charge flow temperature 212 is acceptable, which includes omitting the temperature calibration and correction module 210, where the estimated charge flow temperature 212 is based on the estimated mixture temperature 220. Fig. 2 is set.

[0026] In Fig. Block 402 is a two-dimensional lookup table based on the fuel flow rate 404 and the engine speed 406 to determine a fuel / speed correction factor 407. Parameters such as the fuel flow rate 404 and the engine speed 406 can be obtained from the control module 144. Fig. 1. Determined or received based on speed and flow sensors (not shown). It may include a switch 408 to control the EGR rate based on the EGR proportion 216. Fig. 2. To determine whether the fuel / speed correction factor 407 or a constant 410 without correction should be output. The constant 410 without correction (e.g., a value of one) can be selected as the output of switch 408 if the EGR proportion 216 of Fig. 2 is at or below a threshold value indicating that essentially no EGR is circulating in the engine air system 100 of Fig. 1. In contrast, the fuel / speed correction factor 407 is selected as the output of switch 408 when the EGR proportion 216 of Fig. 2 is above a threshold value indicating that exhaust gas in the engine air system is 100% Fig. 1 is traced back.

[0027] In Fig. 4. A multiplier block 412 multiplies the output of switch 408 by the estimated mixing temperature 220. Fig. 2 and passes the output to a difference block 414 and a summation block 416. The difference block 414 determines a difference between a coolant temperature 418 and the output of the multiplier block 412. The coolant temperature 418 can be obtained from the control module 144. Fig. 1. The coolant temperature is determined or received based on a (not shown) coolant temperature sensor. The output of differential block 414 is scaled by multiplying it by a coolant temperature correction factor 419 and passing it to summation block 416 to be added to the output of multiplier block 412.

[0028] A coolant temperature coefficient correction block 420 calculates the coolant temperature correction factor 419 based on an air mass flow 422 from the intake air mass flow sensor 104. Fig. 1, the vehicle speed 424 and the fan speed 426. The air mass flow 422 can be further corrected to account for a sensor signal delay as a variable delay based on factors such as the volume of the intake manifold piping, the volumetric efficiency, and the engine speed 406 in accordance with a known velocity-density equation calculated per volume. The air mass flow correction can also be applied to other modules that use an air mass flow, such as the EGR proportion estimation module 204. The vehicle speed 424 and the fan speed 426 can be obtained from the control module 144. Fig. 1. Based on various speed sensors (not shown), the coolant temperature coefficient correction block 420 can use a multidimensional lookup table to determine the correction factor 419.

[0029] The output of the summing block 416 can further be smoothed by a flow-based filter 428, which calculates the estimated charge flow temperature 212 as a function of the estimated charge mass flow 214. Fig. 2. The flow-based filter 428 can be implemented as a delay filter to smooth transitions at the estimated charge flow temperature 212. The resulting estimated charge flow temperature 212 represents an estimate of the temperature at the intake manifold temperature sensing position 118, allowing a physical temperature sensor to be moved away from the intake manifold temperature sensing position 118. The estimated charge flow temperature 212 is used for application with other modules or other control logic of the control module 144. Fig. 1. Additional values ​​determined by module 152 for estimating the charge flow temperature can also be provided for other modules or other control logic in control module 144. Fig. 1 will be provided.

[0030] Although the invention has been described with reference to exemplary embodiments, those skilled in the art understand that various modifications can be made and elements can be replaced by equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt the teachings of the invention to a specific situation or material without leaving its essential scope. It is therefore intended that the invention is not limited to the specific embodiments disclosed, but rather that the invention will encompass all embodiments that fall within the scope of the application.

Claims

[1] Engine air system (100) for estimating a charge flow temperature (212), comprising: a temperature sensor (110) at the outlet of a charge air cooler (108), which is designed to receive a first temperature signal (308; T CACO ) to provide; a temperature sensor (142) at the outlet of an exhaust gas recirculation system, which is designed to provide a second temperature signal (312; T ECRO ) to provide; and a control module (144) designed to receive the first temperature signal (308; T CACO ) and the second temperature signal (312; T EGRO ) to receive, wherein the control module (144) includes a charge flow temperature estimation module (152) configured to estimate the charge flow temperature (212) at an intake manifold temperature sensing position (118) based on a combination of the first temperature signal (308; T CACO) multiplied by an estimated fresh air content (318; f AIR ) and the second temperature signal (312; T EGRO ) multiplied by an exhaust gas recirculation component (216; f AGR ) to determine; where the first temperature signal (308; T CACO ) is corrected to account for a time delay between a temperature reading at a location of the temperature sensor (110) at the outlet of the charge air cooler (108) and the intake manifold temperature sensing position (118), and the second temperature signal (312; T EGRO ) is corrected to account for a time delay between a temperature reading at a location of the temperature sensor (142) at the exhaust gas recirculation outlet and the intake manifold temperature sensing position (118). [2] Engine air system (100) according to claim 1, wherein the estimated fresh air fraction (318; f AIR ) and the exhaust gas recirculation rate (216; f AGR) complementary values, so that the estimated fresh air content (318; f AIR ) plus the exhaust gas recirculation component (216; f AGR ) equals one. [3] Engine air system (100) according to claim 1, wherein the module (152) for estimating the charge flow temperature further comprises a temperature calibration and correction module (210) configured to correct the estimated charge flow temperature (212) on the basis of a coolant temperature (418). [4] Engine air system (100) according to claim 3, wherein the estimated charge flow temperature (212) is corrected as a sum of the estimated charge flow temperature (212) and a scaled difference between the coolant temperature (418) and the estimated charge flow temperature (212), wherein the scaled difference is a difference between the coolant temperature (418) and the estimated charge flow temperature (212) multiplied by a coolant temperature correction factor (419) based on an air mass flow (422) and / or a vehicle speed (424) and / or a fan speed (426). [5] Engine air system (100) according to claim 4, wherein the air mass flow (422) is an air mass flow corrected on the basis of a volume of intake manifold piping, a volumetric efficiency and an engine speed. [6] Engine air system (100) according to claim 4, further comprising: a flow-based filter (428) designed to filter the estimated charge flow temperature (212) as a function of the estimated charge mass flow (214) in order to smooth the estimated charge flow temperature (212). [7] Engine air system (100) according to claim 1, wherein the module (152) for estimating the charge flow temperature (212) further comprises a temperature calibration and correction module (210) configured to correct the estimated charge flow temperature (212) on the basis of a fuel / speed correction factor (407). [8] Engine air system (100) according to claim 7, wherein the estimated charge flow temperature (212) is corrected on the basis of the fuel / speed correction factor (407) in response to the fact that the exhaust gas recirculation fraction (216; f AGR) is above a threshold value indicating that exhaust gas is recirculated in the engine air system (100). [9] Engine air system (100) according to claim 1, wherein the module (152) for estimating the charge flow temperature further comprises: a charge mass flow module (202) configured to provide an estimated charge mass flow (214) to a module (204) for estimating the exhaust gas recirculation fraction; wherein the module (204) is designed to estimate the exhaust gas recirculation fraction in order to obtain an exhaust gas recirculation fraction (216; f AGR ) to deliver to a mixing module (208) based on the estimated charge mass flow (214); wherein the mixing module (208) is designed to achieve an estimated mixing temperature (220; T MIX ) based on the exhaust gas recirculation rate (216; f AGR ) to supply to a temperature calibration and correction module (210); and wherein the temperature calibration and correction module (210) is designed to calculate the estimated charge flow temperature (212) based on the estimated mixing temperature (220; T MIX to spend.

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