Methods and systems for airflow control

Abstract

A method for engine airflow control, wherein an engine system (200) comprises a throttle turbine generator (202) and an engine (10), wherein the throttle turbine generator (202) comprises a throttle turbine (206) that drives a turbine generator (210), wherein the throttle turbine (206) is arranged in a throttle bypass (204) around an intake throttle (62) on an intake manifold, wherein the throttle bypass (204) is configured to direct intake air from a position upstream of the intake throttle (62) to a position downstream of the intake throttle (62), the method comprising: Forward adjusting the intake throttle (62) coupled to the throttle turbine (206) based on a driver torque command (608); and further adjusting the inlet throttle (62) based on each of a first function of a pressure differential across the throttle turbine (206) and a second, different function of the pressure differential multiplied by the turbine speed, wherein adjusting the inlet throttle (62) and further adjusting the inlet throttle (62) comprises adjusting an inlet throttle angle of the inlet throttle (62).

Description

Area

[0001] The present invention relates generally to methods and systems for airflow control in an engine system including a throttle turbine generator. Background / Summary

[0002] Document DE 10 2015 114 688 A1 discloses methods and systems for adjusting the operation of a throttle valve turbine generator to enable improved canister emptying. Document DE 10 2006 004 239 A1 discloses a method for controlling a secondary air device of an internal combustion engine used to heat the exhaust gas catalyst. The secondary air device comprises a secondary air charger with a turbine and a compressor. The turbine is arranged in a bypass to the throttle valve of the internal combustion engine, which bypass contains a turbine valve, and is driven by the pressure drop across the throttle valve.

[0003] Engine systems may be designed with devices such as a throttle turbine generator to harness energy from a pressure differential across a throttle that would otherwise be wasted in an engine intake tract. For example, the throttle turbine generator may be driven by a pressure differential across a partially open throttle when the engine is operating at part throttle. In some examples, the throttle turbine generator includes a turbine mechanically coupled to the throttle turbine generator, which may generate power that is supplied to an engine battery. Charging the battery with such a generator may improve the fuel economy of the engine system.

[0004] An example of such an engine system is shown by Leone et al. in US 2013 / 0 092 125 A1. Therein, a throttle turbine generator is positioned in a throttle bypass. A throttle bypass valve is controlled based on an engine airflow demand to adjust the airflow through the throttle turbine generator. Additionally, a throttle position is controlled during engine transients to meet an engine airflow demand.

[0005] However, the inventors of the present invention have recognized potential problems with such a system. For example, if the pressure differential across the intake manifold is used to drive the turbine using the throttle, airflow control around the intake manifold becomes more challenging due to continuously varying speeds of the turbine and / or generator. Additionally, any change in throttle position simultaneously affects two paths in the intake side of the engine, making airflow control via the throttle challenging. To accurately estimate airflow, variables such as throttle angle, the cross-sectional area of the restriction formed by the throttle, the pressure differential across the intake manifold, and turbine speed may need to be adaptively controlled.In order to achieve accurate airflow control in the face of multiple variables, one or more four-dimensional performance maps may need to be generated, stored, and rapidly accessible. However, generating, storing, and accessing complex four-dimensional maps can be time-, memory-, and computationally intensive. Apart from the complexity of generating and accessing the high-dimensional maps, they may also be prohibitively large to store in an engine control unit, particularly due to memory limitations. As another example, at Leone, the throttle position is only adjusted during transients. However, airflow errors can also occur during steady-state conditions due to variations (e.g., instantaneous) in the speed of the turbine and / or generator.

[0006] The inventors have found that by determining the pressure differential generated across the intake manifold as a function of throttle angle, at least one two-dimensional map can be generated (e.g., in real time or in advance) and stored in the memory of an engine control unit. Here, based on each of the pressure differential and the throttle angle, the effective cross-sectional area of the restriction around the throttle can be tabulated. Furthermore, a correction to the effective cross-sectional area of the restriction can be determined, for example, by including the effects of turbine speed, which can be stored as a separate two-dimensional map. By making numerical approximations to the at least two two-dimensional maps, the throttle angle can be accurately determined for effective airflow control.Additionally, from the two two-dimensional maps, it may also be possible to accurately predict the airflow at a given throttle angle, which can then be used, for example, to estimate the airflow into the manifold for torque monitoring. This results in an approach that is less computationally, memory-, and time-intensive without compromising the accuracy of the airflow estimation. Furthermore, airflow control is performed not only during transient conditions, as shown by Leone et al., but also during other conditions, such as steady-state, idle, etc.

[0007] In one example, engine airflow control may be achieved by a method comprising: forwardly adjusting an intake throttle coupled to a throttle turbine based on a driver torque command; and further adjusting the intake throttle based on each of a first function of a pressure differential across the throttle turbine and a second, different function of the pressure differential multiplied by the turbine speed. In this manner, airflow control may be performed accurately and efficiently.

[0008] As an example, in response to a driver torque command, the requested torque may be delivered by an engine by adjusting a throttle angle of an intake throttle. Since adjusting the throttle angle also adjusts an effective cross-sectional area of a restriction formed by the throttle on an intake pipe, an engine control unit may be configured to take into account the influence of turbine speed on the effective cross-sectional area of the restriction. In particular, the control unit may refer to one or more two-dimensional (2D) maps stored in the memory of the control unit to subtract out this effect, thereby enabling precise control of the airflow to deliver the requested torque. For example, the control unit may use a first 2D map to determine a first (e.g.initial) setting for the position (such as angle) of the intake throttle based on a first function of a pressure differential across the throttle turbine. Further, the controller may use another 2D map to determine a second, different (e.g., further) setting to the position of the intake throttle based on each of the pressure differential across the throttle and a turbine speed of a throttle turbine generator coupled in a bypass across the throttle. As such, the maps may also be used, for example, to determine a first amount of airflow based on the throttle angle for torque monitoring. For example, the controller may use a first 2D map to determine an amount of airflow into the engine based on the position (such as angle) of the intake throttle based on a first function of a pressure differential across the throttle turbine.Furthermore, the control unit may use another 2D map to determine a second, different (e.g., further) setting of the airflow amount based on each of the pressure difference across the throttle and a turbine speed of a throttle turbine generator coupled in a bypass across the throttle.

[0009] In this way, precise airflow and torque control can be provided in the presence of an intake throttle turbine and a turbine generator. The technical effect of adjusting an intake throttle angle based on a pressure differential across the throttle turbine and the turbine speed is that the pressure and airflow effects due to the change in throttle angle can be better compensated. By relying on one or more 2D maps, airflow control can be performed with increased accuracy without the use of multiple computationally, memory-, and time-intensive algorithms or maps. In addition, airflow control can be performed over a wider range of engine operating conditions, including transient and steady-state engine operating conditions.Overall, by improving airflow control, it may be possible to obtain fuel economy benefits while maintaining drivability and emissions requirements.

[0010] It is understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that resolve any disadvantages noted above or in any part of the disclosure. Short description of the drawings Fig. 1 shows a schematic representation of an engine. Fig. 2 shows a schematic representation of a throttle turbine coupled to a throttle turbine generator and a throttle in an intake tract of the engine. Fig. 3A shows an exemplary relationship between a throttle angle and an effective cross-sectional area of a constriction formed by the throttle. Fig. Figure 3B shows an example relationship between the throttle angle and the turbine speed. Fig. 4 shows a detailed flowchart illustrating an example method for calculating throttle angle based on a desired engine intake airflow and / or predicting an expected airflow at a given throttle angle. Fig. Figure 5 shows an exemplary relationship between the desired airflow and a downstream throttle pressure at various throttle angles and turbine speeds for a given upstream throttle pressure. Fig. 6 shows a detailed flowchart illustrating a method for controlling intake airflow based on a desired torque by adjusting the throttle angle and / or estimating intake airflow for torque monitoring based on the throttle angle. Fig. Figure 7 shows an example relationship between torque command, intake air flow, throttle angle, and turbine speed. Detailed description

[0011] The following description relates to systems and methods for controlling the airflow of an engine, such as the one in Fig. 1. The engine may include a throttle bypass around a throttle in an intake system of the engine, as shown in Fig. 2. Furthermore, the throttle bypass may include a turbine in communication with an auxiliary generator ( Fig. 2). The airflow in the intake system may be adjusted by adjusting the throttle angle of the throttle. As such, adjusting the throttle angle may further affect an effective cross-sectional area of a constriction formed by the throttle, as shown in Fig. 3A. However, the airflow control in the intake system becomes more demanding due to varying speeds of the turbine and / or generator, as shown in Fig. 3B. A control unit may be configured to perform a routine such as the example routine of Fig. 4, to calculate a throttle angle based on a desired airflow and / or to predict an airflow at a given throttle angle. The engine intake airflow can be controlled while taking into account the effects of turbine speed on the throttle angle, as in Fig. 5. The control unit may also be designed to perform a routine such as the example routine of Fig. 6, to control the engine intake airflow based on a desired torque by adjusting the throttle angle, and / or to estimate the engine airflow for torque monitoring based on the throttle angle. An example control of the airflow and throttle angle based on a torque command and turbine speed is shown in Fig. 7. In this way, the air flow can be precisely controlled.

[0012] Fig. 1 is a schematic diagram showing one cylinder of a multi-cylinder engine 10 that may be included in a propulsion system of an automobile. The engine 10 may be controlled at least in part by a control system including a control unit 12 and by input from a vehicle operator 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. A combustion chamber (i.e., cylinder) 30 of the engine 10 may include combustion chamber walls 32 with a piston 36 positioned therein. The piston 36 may be coupled to a camshaft 40 such that reciprocating motion of the piston is translated into rotational motion of the camshaft. The camshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate gear system.Furthermore, a starter motor may be coupled to the camshaft 40 via a flywheel to enable starting operation of the engine 10.

[0013] Combustion chamber 30 may receive intake air from intake manifold 44 via intake passage 42 and may expel combustion gases via exhaust passage 48. Intake manifold 44 and exhaust passage 48 may selectively communicate with combustion chamber 30 via a respective intake valve 52 and exhaust valve 54. In some embodiments, combustion chamber 30 may include two or more intake valves and / or two or more exhaust valves.

[0014] In this example, intake valve 52 and exhaust valve 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cams and may include one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems operable by controller 12 to vary valve operation. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In alternative embodiments, intake valve 52 and / or exhaust valve 54 may be controlled by electric valve actuation.For example, cylinder 30 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation, including CPS and / or VCT systems.

[0015] A fuel injector 66 is shown directly coupled to the combustion chamber 30 for injecting fuel directly therein in proportion to the pulse width of the FPW signal received from the control unit 12 via an electronic driver 68. In this manner, the fuel injector 66 provides what is known as direct injection of fuel into the combustion chamber 30. The fuel injector may be mounted, for example, on the side of the combustion chamber or in the top of the combustion chamber. Fuel may be supplied to the fuel injector 66 from a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail.In some embodiments, the combustion chamber 30 may alternatively or additionally include a fuel injector disposed in the intake manifold 44 in a configuration that provides what is known as port injection of fuel into the intake manifold upstream of the combustion chamber 30.

[0016] The intake manifold 42 may include a throttle 62 (also known as an intake throttle) with a throttle plate 64. In this particular example, the position of the throttle plate 64 may be varied by the controller 12 via a signal provided to an electric motor or actuator included in the throttle 62, a configuration commonly referred to as electronic throttle control (ETC). In this manner, the throttle 62 may be operated to vary the intake air supplied to the combustion chamber 30 among other engine cylinders. The position of the throttle plate 64 may be communicated to the controller 12 via a throttle position (TP) signal. The intake manifold 42 may include a mass air flow sensor 120 and / or an absolute manifold pressure sensor 122 for providing respective MAF and MAP signals to the controller 12.In some embodiments, one or more pressure sensors may be arranged upstream and / or downstream of the throttle to estimate a pressure difference across the throttle and generate a pressure difference signal for the control unit 12.

[0017] Furthermore, a throttle turbine generator 202 is coupled to the intake tract 42 in a bypass around the throttle 62. The throttle turbine generator 202, which is described with reference to Fig. 2, includes a turbine that drives a turbine generator (also known as an auxiliary generator). Typically, a pressure differential is created across the throttle 62, which is then used to drive the turbine and turbine generator. For example, when the throttle is fully open, the intake manifold is typically at ambient atmospheric pressure. For example, when the throttle is partially closed, a manifold vacuum may develop as the intake drops below ambient pressure, creating the pressure differential. The auxiliary generator may provide charge to a battery of the engine, supplementing charging by a mechanically driven primary generator and / or as the main charging source, for example, when the primary generator degrades or fails.However, due to turbine operation, airflow control around the intake manifold becomes more challenging due to the varying speeds of the turbine and / or generator. Additionally, any change in throttle position simultaneously affects two paths on the intake side of the engine, making airflow control via the throttle challenging, as discussed here with reference to . Fig. 3A and Fig. 3B.

[0018] An ignition system 88 may provide an ignition spark to the combustion chamber 30 via a spark plug 92 in response to a pre-ignition signal SA from the controller 12 under select operating modes. Although the spark ignition components are shown, in some examples, the combustion chamber 30 or one or more other combustion chambers of the engine 10 may be operated in a compression ignition mode with or without an ignition spark.

[0019] An exhaust gas sensor 126 is shown coupled to the exhaust tract 48 upstream of an emissions control device 70. The sensor 126 may be any suitable sensor to provide an indication of the exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wideband exhaust oxygen), a dual-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. The emissions control device 70 is shown disposed along the exhaust tract 48 downstream of the exhaust gas sensor 126. The device 70 may be a three-way catalyst (TWC), a NOx trap, various other emissions control devices, or combinations thereof. In some embodiments, during operation of the engine 10, the emissions control device 70 may be periodically reset by operating at least one cylinder of the engine within a particular air / fuel ratio.

[0020] The control unit 12 is in Fig. 1 as a microcomputer including a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, shown as a read-only memory chip 106 in this particular example, random access memory 108, keep-alive memory 110, and a data bus. The control unit 12 may receive various signals from sensors coupled to the engine 10, in addition to the signals discussed above, including: induced mass air flow (MAF) measurement from the mass air flow sensor 120; engine coolant temperature (ECT) from the temperature sensor 112 coupled to a cooling sleeve 114; a profile ignition pickup (PIP) signal from a Hall sensor 118 (or other type) coupled to the camshaft 40; and a throttle position (TP) from a throttle position sensor; and an absolute manifold pressure (MAP) signal from sensor 122, etc.An engine speed signal, RPM, may be generated by control unit 12 from the PIP signal. The turbine speed of the turbine may be derived by control unit 12 based on the output of the throttle turbine generator. Alternatively, the turbine speed may be measured via a dedicated turbine speed sensor. The absolute manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of a vacuum, or pressure, in the intake manifold. In some embodiments, one or more pressure sensors may be located upstream and / or downstream of the throttle to estimate a pressure differential across the throttle. It should be noted that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor may provide an indication of engine torque.Furthermore, this sensor, along with the detected engine speed, may provide an estimate of the charge (including air) being introduced into the cylinder. In one example, sensor 118, which is also used as an engine speed sensor, may generate a predetermined number of evenly spaced pulses with each revolution of the camshaft.

[0021] The read-only memory storage medium 106 may be programmed with computer-readable data representing instructions executable by the processor 102 to perform the methods described below, as well as other variations that are anticipated but not specifically listed.

[0022] As described above, Fig. 1 only one cylinder of a multi-cylinder engine, and each cylinder may similarly include its own set of intake / exhaust valves, fuel injector, spark plug, etc.

[0023] If you continue with Fig. 2, a throttle turbine generator 202 is shown in an engine system 200 that implements the system described above with reference to Fig. 1. The throttle turbine generator 202 includes a turbine 206 (also known as a throttle turbine) and a throttle bypass valve 208 disposed within the throttle bypass 204, and a turbine generator 210 driven by the turbine 206. As such, the turbine 206 is disposed within the throttle bypass 204 around the intake throttle 62 on the intake manifold, and the throttle bypass may be configured to direct intake air from a position upstream of the intake throttle to a position downstream of the intake throttle. In some embodiments, the throttle turbine generator may not include a throttle bypass valve 208. Instead, the throttle may, for example, have a wedge-shaped vane that blocks airflow to the throttle bypass under some conditions.

[0024] The throttle turbine generator 202 utilizes energy typically wasted by throttling engine intake air. For example, the change in pressure across the intake throttle 62 can be used to direct airflow through the turbine 206. The turbine 206 drives the turbine generator 210 (also referred to herein as an auxiliary generator), which provides power to the battery 212. In such a configuration, the overall efficiency of the engine system can be improved because, for example, charging of the battery 212 via a mechanically driven primary generator 214 can be reduced and charging via the auxiliary generator 210 can be increased during some operating conditions.

[0025] As shown, intake air flows through the intake tract 42 and through the intake throttle 62. As described above, a throttle position may be varied by the control unit 12 such that an amount of intake air delivered to the cylinders of the engine is varied. The throttle bypass 204 directs intake air from a position upstream of the intake throttle 62 and around the intake throttle 62 to a position downstream of the throttle 62. The intake air may be directed through the throttle bypass 204, for example, by a pressure differential across the throttle. Further, in the Fig. 2, the throttle turbine generator 202 includes a throttle bypass valve 208. One or more of the throttle bypass valve 208 and the intake throttle 62 may be modulated based on signals received from the controller 12 to adjust the flow of intake air to the turbine 206, as described below with reference to Fig. 3A and Fig. 3B. For example, the controller may send a signal to an electromechanical actuator coupled to the throttle, where the actuator causes an angle of the throttle to be increased by moving the throttle to a more open position or causes the angle of the throttle to be decreased by moving the throttle to a more closed position. In some examples, the throttle bypass valve 208 may be an on / off valve that opens and closes the throttle bypass 204. In other examples, the throttle bypass valve 208 may be a flow modulation valve that controls a variable amount of airflow through the throttle bypass 204. The throttle bypass valve 208 may be a plunger or spool valve, a gate valve, a throttle valve, or other suitable flow control device.Furthermore, the throttle bypass valve 208 may be actuated by a solenoid, a pulse width modulated solenoid, a DC motor, a stepper motor, a vacuum diaphragm, or the like.

[0026] In some embodiments, in addition to, or instead of, adjusting the throttle valve angle, an angle (or on / off state) of the throttle bypass valve may be adjusted. For example, a dependency may be added to the first and second functions to calculate a predicted effective area, as described with reference to Fig. 4 is executed (as steps 410 and 412 of Fig. 4). However, adding this dependency to the maps may increase the map input dimension from 2D to 3D.

[0027] The airflow directed through the throttle bypass 204 flows through the turbine 206, which rotates the auxiliary generator 210 using energy extracted from the airflow. The auxiliary generator 210 generates power, which is supplied to the battery 212. The battery 212 can supply power to various components of an electrical system of the vehicle in which the engine system 200 is located, such as lights, pumps, fans, fuel injection, ignition, air conditioning, and the like. The battery 212 can also be charged by the primary generator 214, which is mechanically driven by the engine 10. Charging of the battery 212 can be coordinated between the primary generator 214 and the auxiliary generator 210 to increase the overall efficiency of the system.For example, the auxiliary generator 210 may supply power to the battery 212 during conditions when supplying power to the battery 212 by the primary generator 214 would increase fuel consumption, such as during vehicle cruising or acceleration. Further, the auxiliary generator 210 may supply power to the battery 212 when the primary generator 214 is degraded or fails. The auxiliary generator 210 may be a less powerful generator, for example, producing less power than the primary generator 214. In some examples, the intake throttle 62 may be adjusted to adjust an amount of energy generated by the turbine generator coupled to the turbine, as explained below. Adjusting the amount of energy generated in the turbine generator may include increasing an electrical output of the turbine generator 210 under selected operating conditions.Adjusting the amount of energy generated in the turbine generator may further include charging one or more of a battery and a primary generator using the amount of energy generated in the turbine generator. In one example, a speed of the throttle turbine (the turbine speed) may be derived based on an electrical output (e.g., current or voltage) of the generator. In another example, the turbine speed may be estimated by a speed sensor coupled to the turbine (e.g., to the turbine shaft).

[0028] The control unit 12 receives signals from the various sensors of Fig. 1 and Fig. 2 and uses the different actuators of Fig. 1 and Fig. 2, to adjust engine operation based on the received signals and instructions stored in a memory of the control unit. For example, adjusting the intake throttle may include adjusting an electromechanical actuator coupled to a throttle plate in the intake system to rotate the throttle valve by the calculated angle by sending a control signal from the control unit to the actuator.

[0029] As described above, a pressure differential across the throttle 62 can be used to direct airflow through the turbine 206 (also referred to as the throttle turbine). When this pressure differential is used to operate the throttle turbine using the throttle, airflow control around the intake manifold 44 becomes challenging due to the varying speeds of the throttle turbine and / or generator. Furthermore, any change in the throttle position of the throttle 62 simultaneously affects two paths (e.g., throttle bypass 204 and intake tract 42) in the intake side of the engine, making airflow control via the throttle challenging. However, it may be possible to increase the accuracy of the airflow control without significantly increasing computational complexity by incorporating the effects of turbine speed, as explained below.

[0030] As such, the airflow through the constriction formed by the throttle can depend on the effective cross-sectional area of the constriction and the pressure difference occurring across the throttle turbine. Mathematically, this can be expressed as equation (1): W=AEPusRTusφ(PdsPus) where W is the air flow, A E is the effective cross-sectional area of the constriction, P us the upstream pressure is, P ds the downstream pressure is T us is the upstream temperature, and R is the gas constant. Here, the function φ is given by equation (2): φ(x)=2γγ−1(x2γ−xγ+2γ) where x is saturated at the flow restriction and is given by equation (3): x=max(PdsPus,2γ+1γγ−1) where γ is the specific heat ratio for the gas.

[0031] In equations (1) to (3), R and γ may be constants or may have time-varying values estimated by the engine control unit. As such, the flow through the intake air path equipped with a turbine and / or a generator is described as a restriction where an effective area A E is a function of the thermodynamic conditions, the valve angle, and the state of the turbine / generator. Mathematically, this can be represented as equation (4): AE=F1(α,ΔP)[1−F2(α,ΔP)ω] where ΔP - P us -P ds is the pressure difference across the throttle turbine, ω is the turbine speed, and α is the throttle angle. Here, the first term of equation (4) or the first function, F1, represents the effective area A Ewhen the turbine is stationary or rotating very slowly (for example ω~0), and the second term or function F2 represents a correction for the effective area A E , if turbine effects are taken into account (e.g., ω≠0). As such, the product of ωF1F2 can be a third function F3, which describes the proportionality constant by which the effective area decreases with increasing turbine speed. The first and second functions are graphically represented in curves 300 and 350 of Fig. 3A or Fig. 3B.

[0032] If you continue with Fig. 3A, curve 300 shows exemplary relationships between a throttle angle and an effective cross-sectional area of the constriction formed by the throttle at various pressure differences ΔP across the throttle turbine. Here, the effective cross-sectional area A Erepresented by the first function F1 when there is no turbine / generator in the throttle bypass. The throttle angle is shown along the horizontal axis, and the effective cross-sectional area (also the same as the first F1 function of equation (4)) is shown along the vertical axis. Curve 302 shows the effective cross-sectional area at a higher pressure differential ΔP when the turbine speed is zero, and curve 304 shows the effective cross-sectional area at a lower pressure differential when the turbine speed is still zero. For example, curve 302 shows the effective cross-sectional area at ΔP of 14 inHg, and curve 304 shows the effective cross-sectional area at ΔP of 5 inHg.As the throttle angle increases, the flow through the throttle turbine increases (curves 302 and 304), reaching a maximum around the point when the channel (i.e., the inlet to the throttle bypass, such as the throttle bypass 204 of . Fig. 2) is fully open. Specifically, as the intake throttle opens, it gradually exposes the intake tract to the throttle turbine. Once the passage is fully open and the valve is opened further, the path passes through the throttle with little resistance, and most of the flow bypasses the turbine.

[0033] However, if the turbine / generator is present in the throttle bypass, in order to accurately determine the effective cross-sectional area of the restriction around the throttle, a correction is applied as described in equation (4). Here, the second term or function F2 is the correction for the turbine speed and is shown in curve 350 of Fig. 3B. Curve 354 shows a percentage correction for the effective cross-sectional area at a higher pressure differential when the turbine speed is non-zero, and curve 352 shows the effective cross-sectional area at a lower pressure differential when the turbine speed is non-zero. For example, curve 354 shows the correction at a ΔP of 14 inHg, and curve 352 shows the correction at a ΔP of 5 inHg. As such, curves 300 and 350 may be generated based on the performance maps / tables stored in the controller's memory.

[0034] By comparing curves 302 and 354, and similarly curves 304 and 352, the effect of turbine speed on the effective cross-sectional area around the throttle can be more reliably determined. Here, when there is no turbine, the effective cross-sectional area continues to increase with throttle angle (curve 302). However, when the effects of turbine speed are included, the effective cross-sectional area has a more complicated profile (curve 354). In curve 354, between α0 and α1, the correction increases as the throttle angle increases from α0 to α1. However, as the throttle angle is increased beyond α1, the correction begins to decrease with increasing throttle angle (curve 354). The effects are more pronounced when the pressure difference is lower (curve 352). Here, the correction increases as the throttle angle increases from α1 to α2 (curve 352). When the throttle angle is increased beyond α2, the correction begins to fall steeply (curve 352).

[0035] To account for the effects of turbine speed on intake airflow and to accurately determine the airflow, four variables—throttle angle, cross-sectional area of the restriction formed by the throttle, pressure differential across the intake manifold, and turbine speed—may need to be adaptively controlled. Here, for a desired airflow based on a torque command, the throttle angle can be determined, for example, by solving equation (4). For this purpose, four-dimensional performance maps (also called lookup tables) containing these variables can be rapidly generated and must be rapidly accessible to accurately determine the throttle angle for the desired airflow. However, generating, storing, and accessing complex four-dimensional maps can be time-, memory-, and computationally intensive.

[0036] The inventors have identified an approach that includes numerical adjustments (e.g., numerical approximations) that use relatively straightforward two-dimensional power maps to solve equation (4) and accurately control the airflow in the engine system, as in Fig. 4. Instructions for performing method 400 and the remaining methods encompassed herein may be executed by a control unit based on instructions stored in a memory of the control unit and in conjunction with signals received from sensors of the engine system, such as those described above with reference to Fig. 1 and Fig. 2. The control unit may use motor actuators of the motor system to adjust motor operation according to the procedures described below.

[0037] The procedure 400 of Fig. Figure 4 describes a method based on numerical approximations to accurately determine the throttle angle for a desired airflow. Additionally, method 400 can be used to predict the airflow at a specific throttle angle for torque monitoring. Specifically, the method derives the throttle angle and predicts an intake airflow by solving equation (4) without resorting to complex four-dimensional performance maps. However, it is understood that additional 4D maps can be used if desired.

[0038] Method 400 begins at 402, where engine operating parameters may be estimated and / or determined. Operating parameters such as pressure (P us and P ds ), temperature (T us ), turbine speed (ω), etc., can be controlled by the control unit (such as the control unit 12 of Fig. 1) measured or estimated based on the output of one or more sensors. For example, P us and P ds measured / estimated by one or more pressure sensors located upstream and downstream of the throttle. T us can be measured or estimated by temperature sensors, and the turbine speed can be measured or estimated, for example, from the output of the turbine generator or via a speed sensor coupled to the turbine shaft. Here, the pressures P us and P dsto the upstream and downstream pressures, respectively, and can be further used to estimate a pressure difference ΔP across the engine intake throttle. In addition to operating parameters such as pressure, temperature, and turbine speed, thermodynamic parameters can also be determined, such as y, which is the specific heat ratio for air, and R, which is the gas constant. As such, these thermodynamic parameters are calibrated constants (e.g., γ = 1.4 and R = 287 J / kg K). In some examples, these thermodynamic parameters can be further based on the temperature and composition of the intake air.

[0039] Other engine operating parameters that may be assessed include engine speed, engine temperature, boost pressure, EGR (e.g., flow rate or percentage), etc.

[0040] In 404 of the procedure 400, factors such as RTusPus and φ(PdsPus) calculated based on operating parameters and thermodynamic parameters measured / estimated in 402. These factors correspond to the airflow through the restriction given by equations (1) and (2). Then, at 405, the method determines whether airflow control or airflow estimation is requested. If airflow control is requested, then at 406, a desired effective area of the restriction formed by the throttle, A E *, based on a desired airflow W*. Otherwise, if an airflow estimate is requested, then at 410 an airflow prediction at a given throttle angle for torque monitoring is determined.

[0041] At 406 the desired effective area A E*, which is determined based on a desired airflow W* (which is further based on a torque command), from equation (1) and can be further written as equation (5): AE∗=W*(RTusPusφ(PdsPus)) where φ is given by equations (2) and (3). Here, for example, W* is determined based on a torque command. The method then proceeds to 408 to solve for the desired throttle angle α*. The desired throttle angle α* is determined by solving equation (4), which is rewritten below as equation (6): AE∗=F1(α∗,ΔP)[1−F2(α∗,ΔP)ω]

[0042] The solution for α* can be determined by solving the nonlinear equation (6). However, equation (6) can be difficult to solve, and solving it itself can also be time-consuming. The inventors have found that, for example, by including numerical approximations, it may be possible to solve equation (6) without generating complex four-dimensional maps or tables.

[0043] A solution example is shown below, which uses an iterative procedure using a numerical Newton approximation method to solve for α*. Here, the following equation (7) is used: αk+1=αk−F1(αk,ΔP)[1−F2(αk,ΔP)ω]−AE∗F1'(αk,ΔP)[1−F2(αk,ΔP)ω]−F1(αk,ΔP)[F2'(αk,ΔP)ω] for k = 0,1, ... etc. The output value α0 can be used as the current throttle angle or given by equation (8): α0=F1−1(AE*,ΔP) where the inverse of F1(α,ΔP) with respect to α is used. The values of F1'(αk,ΔP) and F2'(αk,ΔP) denote sensitivities or derivatives of the functions F1 (α, ΔP) and F2 (α, ΔP) with respect to α. The functions F1'(αk,ΔP),F2'(αk,ΔP) and F1−1(AE*,ΔP) can be stored as performance maps or lookup tables, which are then accessed by the control unit to perform online calculations.

[0044] In this way, by determining the pressure difference created across the intake manifold as a function of throttle angle, a two-dimensional map can be generated and stored in an engine control unit. Furthermore, a correction to the effective cross-sectional area of the restriction can be determined, for example, by including the effects of turbine speed, which can be stored as a separate two-dimensional map. By making numerical approximations to the two two-dimensional maps, the throttle angle for effective airflow control can be accurately determined. In one example, the least complex solution is obtained if the calculations are performed once, e.g., setting k to 0 and taking the value of α* as α1. The iteration can be stopped after any of a selected number of iterations, and / or until |α k+1 -α k| is smaller than a threshold (for example, a predetermined value), and the last calculated value of α k+1 is used as a solution for the throttle angle α*.

[0045] Here, an airflow may be estimated based on a desired torque. Further, based on the estimated airflow, the throttle angle may be determined by making numerical approximations as described, and the throttle may be adjusted to the calculated throttle angle. Here, adjusting the intake throttle includes adjusting an electromechanical actuator coupled to a throttle plate in the intake system to rotate the throttle valve by the calculated angle by sending a control signal from the control unit to the actuator. As such, adjusting the throttle angle of the intake throttle further includes adjusting an amount of energy generated, for example, in a turbine generator coupled to the throttle turbine.Adjusting the amount of energy generated in the turbine generator may further include increasing an electrical output of the turbine generator under selected operating conditions and may also include charging one or more of a battery and a primary generator using the amount of energy generated in the turbine generator.

[0046] Referring again to 410, if an accurate prediction of airflow at a given throttle angle is desired, the method 400 includes calculating the predicted effective area AE^ based on an input throttle angle. Here, the predicted effective area can be mathematically represented as equation (9): AE^=F1(α,ΔP)[1−F2(α,ΔP)ω] where ΔP and ω are determined in 402 of method 400. Next, the method proceeds to 412, where the predicted airflow Ŵ is calculated. As such, the predicted airflow can be mathematically represented as equation (10): W^=AEPusRTusφ(PdsPus) where the variable calculated or estimated in 402 can be used to predict the airflow. Similar to the numerical approximations made to determine the throttle angle α*, numerical approximations can be made to equation (9) to predict the airflow Ŵ at a given throttle angle α. As such, the predicted airflow can be used to estimate the flow into the intake manifold for state estimation, which can be further used for torque monitoring and for model reference control applied to the throttle. Thus, instead of calculating inverses of functions and using four-dimensional maps, which can be time-, memory-, and computationally intensive, it may be possible to predict the airflow for a given throttle angle by making numerical approximations quickly and efficiently without compromising accuracy.The airflow control procedure is described in . Fig. 5. In this way, the throttle angle for a desired flow and also the air flow for a given throttle angle can be determined using numerical approximation methods, thereby achieving accurate air flow control.

[0047] Fig. Figure 5 shows an exemplary relationship between the desired airflow and the throttle downstream pressure at various throttle angles and turbine speeds. Here, the upstream pressure can be kept substantially constant (e.g., 22.4 in Hg). In curve 500, the downstream pressure is shown along the horizontal axis, and the flow through the throttle is shown along the vertical axis. Curve 502 shows the airflow as a function of downstream pressure when the turbine is stalled or at a turbine speed ω1 (or, for example, ω1 = 0) when the throttle angle α1 is (e.g., α1 = 12°). Curve 504 shows the airflow as a function of downstream pressure when the turbine speed is ω2 (e.g., ω2 = 60,000 rpm) at the same throttle angle α1. For example, the difference between curves 502 and 504 can determine the effects of turbine speed on flow.Curve 506 shows the air flow as a function of downstream pressure when the turbine is at a standstill or at turbine speed ω1 (or, for example, ω1 = 0) when the throttle angle α2 is (for example, α1 = 10°). Curve 504 shows the air flow as a function of downstream pressure when the turbine speed is ω2 (for example, ω2 = 60,000 rpm) at the throttle angle α2. For example, it is possible to predict the air flow W1 for pressure P1 using the throttle angle α2 and the turbine speed ω2.

[0048] Curve 500 also shows a desired flow curve (curve 510) that relates to the downstream pressure P dsand flow W2, as shown. As such, the desired airflow W2 can be calculated based on a desired torque. For a given flow (curve 510), the intersection between the desired curve (curve 510) and the curve for the measured turbine speed defines the desired angle. For example, if the measured turbine speed is ω2, then the intersection of curve 510 and curve 508 yields the desired angle as α2. In this way, the throttle angle settings for a desired flow can be calculated based on a torque command.

[0049] If you continue with Fig. 6 shows a method 600 for controlling airflow into the engine. Specifically, the method 600 adjusts the airflow into the engine cylinders (e.g., load) based on the throttle setting while taking into account the turbine rotation speed. For example, the turbine speed can affect the airflow by up to 10%, which can be corrected by the method to obtain accurate airflow control and torque delivery. Additionally, the method 600 predicts the airflow to the engine cylinders based on an input throttle angle, which can then be used, for example, to estimate airflow into the manifold for torque monitoring.

[0050] At 602 of method 600, engine operating conditions are determined. The operating conditions may include engine speed, engine load, intake air flow rate and / or pressure, throttle position, accelerator pedal position, ambient pressure, ambient temperature, turbine speed, and the like. The operating conditions may further include determining whether the engine is at steady state, idling, transient conditions, etc. In addition to determining operating conditions, thermodynamic conditions may also be determined. As such, determining thermodynamic conditions includes calculating thermodynamic parameters such as the specific heat ratio for the gas, y, the gas constant, R, etc.

[0051] Once the operating conditions are determined, method 600 proceeds to 604, where it may be determined whether airflow control is requested. For example, airflow control may be requested when a sudden increase (e.g., due to a positive load change) or a sudden decrease (e.g., due to a negative load change) in torque demand occurs. In some examples, airflow control may be requested when torque demand steadily increases and / or steadily decreases by a threshold amount. In still other examples, airflow control may be requested in response to a request to adjust an auxiliary generator output.

[0052] If airflow control is requested, method 600 proceeds to 606, where a throttle angle may be adjusted based on the desired airflow to meet torque requests. As such, the throttle angle may be determined by solving equation (6) by making numerical approximations, as discussed above. Method 600 includes performing airflow control by making forward adjustments to an intake throttle coupled to a throttle turbine based on a driver torque command at 608. Method 600 further includes adjusting the intake throttle based on each of a first function of a pressure differential across the throttle turbine and a second, different function of the pressure differential multiplied by the turbine speed at 610. As such, adjusting the intake throttle further includes adjusting a throttle angle of the intake throttle.Here, adjusting the intake throttle includes adjusting an electromagnetic actuator coupled to a throttle plate in the intake system to rotate the throttle valve by the calculated angle by sending a control signal from the controller to the actuator. Adjusting the intake throttle further includes adjusting an effective cross-sectional area of a restriction formed by the intake throttle on an intake pipe at 612. Adjusting the throttle angle may be further based on a difference between the first pressure difference function and a third pressure difference function, wherein the third pressure difference function is different from each of the first function and the second function at 614. The third function may be a product of each of the first function, the second function, and the turbine speed.The effective cross-sectional area may increase proportionally to the third function when the turbine speed is lower than a threshold, and the effective cross-sectional area may decrease proportionally to the third function when the turbine speed is higher than the threshold. Then, method 600 ends.

[0053] In this way, precise airflow control can be maintained in the presence of the turbine and turbine generator, making it possible to obtain fuel economy benefits while maintaining drivability and emissions requirements.

[0054] If no airflow control is requested at 604, method 600 proceeds to 612 where it is determined whether an airflow estimation is requested. If an airflow estimation is requested, method 600 then proceeds to 618 where an intake airflow across the throttle turbine may be predicted or adjusted. The adjustment of the intake airflow across the throttle turbine may be based on the intake throttle angle at 620. Further, the adjustment of the intake airflow may also be based on the first function of the intake throttle angle and a second, different function of the intake throttle angle multiplied by the turbine speed at 622. Here, the turbine speed is determined, for example, based on a pulse output of the auxiliary generator.Once intake airflow is adjusted or predicted, method 600 proceeds to 624, where torque may be monitored based on the predicted airflow, and the method ends. However, if no airflow estimate is requested at 616, method 600 proceeds to 626, where airflow may not be adjusted, and then the method ends. In this way, accurate airflow control may be maintained using functions and numerical approximations by both estimating the intake throttle angle for a desired airflow to meet torque requests and further predicting the airflow at a given throttle angle for torque monitoring.

[0055] With reference now to Fig.7, a map 700 shows an exemplary airflow control during two states, the first state including adjusting the throttle angle based on a desired airflow, and the second state including adjusting the airflow based on the throttle angle. Curve 702 shows the desired airflow, further based, for example, on a desired torque command. Curve 710 shows the turbine speed, estimated, for example, from the output of the turbine generator. Curve 706 (dashed line) shows the throttle angle determined based on the desired airflow. Here, during the first state, the inlet throttle angle (curve 706) of a throttle coupled to a throttle turbine may be adjusted based on each of a first function of a pressure differential across the throttle turbine and a product of a second, different function of the pressure differential and the turbine speed (curve 710).

[0056] Between t0 and t1, a first condition may be confirmed in which increased airflow may be desired (curve 702). Increased airflow may be desired, for example, when torque demand increases. Thus, based on a request for airflow control, the throttle angle may be adjusted while maintaining airflow across the throttle turbine, for example, to meet an increase in the driver torque command. Taking into account the turbine speed (710), the throttle angle may be increased (curve 706). Further, the amount by which the intake throttle angle is increased is determined based on equations (5) and (6), as discussed above.Briefly, the adjustment of the inlet throttle angle of a throttle coupled to a throttle turbine may be based on either a first function of a pressure differential across the throttle turbine and a product of a second, different function of the pressure differential and the turbine speed. Further, during the first condition, the adjustment of the throttle angle includes a forward adjustment during nominal engine operation and further includes a feedback adjustment during engine idle. For example, if turbine speed effects are negligible, the adjustment of the throttle's inlet throttle angle may be based on the first function when the throttle turbine condition includes one or more of stalling or spinning below a threshold speed.During the first state, a request for airflow control may be received, and the throttle angle may be adjusted while maintaining airflow across the throttle turbine and while issuing a driver torque command. In this way, precise airflow control to satisfy torque commands can be achieved by considering the effects of turbine speed. The technical effect of adjusting the throttle angle based on the desired flow while considering turbine speed is that the airflow to the engine is more precisely controlled.

[0057] Between t1 and t2, a second state may be confirmed at which a request for an airflow estimate may be received. During the time between t2 and t3, the airflow (curve 704) across the throttle turbine may be adjusted while maintaining the intake throttle angle (curve 708) and while estimating the airflow into a manifold, as explained with reference to equations (9) and (10). In brief, during the second state between t2 and t3, the intake airflow (curve 704) across the throttle turbine may be adjusted based on each of a first function of the intake throttle angle (function based on the throttle angle, indicated by curve 708) and the product of a second, different function of the intake throttle angle and the turbine speed (curve 714).Thus, during the second state, a request for airflow estimation may be received and the airflow across the throttle turbine may be adjusted while maintaining the inlet throttle angle and while estimating the airflow into the manifold.

[0058] In this way, using functions and numerical approximations, accurate airflow control can be maintained by both estimating the intake throttle angle for a desired airflow to meet torque requirements and predicting the airflow at a given throttle angle for torque monitoring. The technical effect of setting the throttle angle based on the desired flow and further predicting the airflow based on the throttle angle while considering the turbine speed is to more accurately control the airflow to the engine and more accurately control the torque monitoring.

[0059] The systems and methods described above also provide a method for engine airflow control, the method comprising: forwardly adjusting an intake throttle coupled to a throttle turbine based on a driver torque command; and further adjusting the intake throttle based on each of a first function of a pressure differential across the throttle turbine and a second, different function of the pressure differential multiplied by turbine speed. In a first example of the method, adjusting the intake throttle and further adjusting the intake throttle may additionally or alternatively comprise adjusting a throttle angle of the intake throttle. A second example of the method optionally includes the first example and further comprises wherein adjusting the intake throttle comprises adjusting an effective cross-sectional area of a restriction formed by the intake throttle at an intake tube.A third example of the method optionally includes one or more of the first and second examples and further includes further adjusting the throttle angle based on a difference between the first function of pressure difference and a third function of pressure difference, wherein the third function of pressure difference is different from each of the first function and the second function. A fourth example of the method optionally includes one or more of the first to third examples and further includes wherein the third function is a product of each of the first function, the second function, and the turbine speed.A fifth example of the method optionally includes one or more of the first to fourth examples and further includes, wherein the effective cross-sectional area increases proportionally to the third function when the turbine speed is lower than a threshold, and wherein the effective cross-sectional area decreases proportionally to the third function when the turbine speed is higher than the threshold. A sixth example of the method optionally includes one or more of the first to fifth examples and further includes, wherein adjusting the throttle angle of the intake throttle further includes adjusting an amount of energy generated in a turbine generator coupled to the throttle turbine.A seventh example of the method optionally includes one or more of the first to sixth examples and further includes, wherein the throttle turbine is disposed in a throttle bypass around the intake throttle on an intake pipe, the throttle bypass configured to direct intake air from a position upstream of the intake throttle to a position downstream of the intake throttle. An eighth example of the method optionally includes one or more of the first to seventh examples and further includes, wherein adjusting the amount of power generated in the turbine generator comprises increasing an electrical output of the turbine generator under selected operating conditions.A ninth example of the method optionally includes one or more of the first to eighth examples and further includes charging one or more of a battery and a primary generator using the amount of energy generated in the turbine generator. A tenth example of the method optionally includes one or more of the first to ninth examples and further includes calculating the turbine speed based on a pulse output of the turbine generator.

[0060] The systems and methods described above also provide a method, the method comprising: during a first condition, adjusting an inlet throttle angle of a throttle coupled to a throttle turbine based on each of a first function of a pressure differential across the throttle turbine and a product of a second, different function of the pressure differential and the turbine speed; and during a second condition, adjusting an intake airflow across the throttle turbine based on each of a first function of the inlet throttle angle and a product of a second, different function of the inlet throttle angle and the turbine speed.In a first example of the method, the method may additionally or alternatively comprise adjusting the intake throttle angle of the throttle based on the first function when the condition of the throttle turbine comprises one or more of stalled or spinning below a threshold speed. A second example of the method optionally comprises the first example and further comprises, wherein during the first condition, a request for airflow control is received. A third example of the method optionally comprises one or more of the first and second examples and further comprises, wherein during the first condition, the intake throttle angle is adjusted while maintaining airflow across the throttle turbine and while issuing a driver torque command.A fourth example of the method optionally includes one or more of the first through third examples, and further includes, wherein during the first state, adjusting the intake throttle angle includes a forward adjustment during nominal engine operation, and further includes a return adjustment during engine idle. A fifth example of the method optionally includes one or more of the first through fourth examples, and further includes, wherein during the second state, a request for an airflow estimate is received. A sixth example of the method optionally includes one or more of the first through fifth examples, and further includes, wherein during the second state, intake airflow across the throttle turbine is adjusted while maintaining the intake throttle angle and while estimating airflow into a manifold.

[0061] The systems and methods described above also provide a system for an engine comprising: a throttle disposed in an intake tract of the engine; a throttle bypass configured to direct intake air from a position upstream of the throttle to a position downstream of the throttle; one or more pressure sensors disposed upstream and / or downstream of the throttle for estimating a pressure differential across the throttle; and a turbine disposed in the throttle bypass, the turbine configured to drive an auxiliary generator in electrical communication with a battery, the battery in further electrical communication with a primary generator.In a first example of the system, the system may additionally or alternatively comprise a control unit having computer-readable instructions stored in a non-transitory memory, configured to: in response to a request for adjustment of an output of the auxiliary generator, adjust an angular position of the throttle based on each of a first function of a pressure difference across the turbine and a second, different function of the pressure difference multiplied by the turbine speed.A second example of the particulate sensor optionally includes the first example and further comprises, wherein the controller further comprises instructions to, in response to a request for an airflow estimate, adjust an intake airflow across the turbine based on each of the first function of the angular position of the throttle and a second, different function of the angular position of the throttle multiplied by the turbine speed, wherein the turbine speed is determined based on a pulse output of the auxiliary generator.

[0062] It should be noted that examples of control and estimation routines included herein may be used with various engine and / or vehicle system designs. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be performed by the control system, including the control unit in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-threaded, multi-processing, and the like. As such, various illustrated actions, operations, and / or functions may be performed in parallel, or in some cases omitted, in the illustrated sequence.Similarly, the order of processing is not required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations, and / or functions may be performed repeatedly depending on the particular strategy employed. Further, the described actions, operations, and / or functions may graphically represent code to be programmed into non-transitory memory of the computer-readable storage medium in the engine control system, wherein the described actions are performed by execution of the instructions in a system including the various engine hardware components in combination with the electronic control unit.

[0063] It is understood that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, as numerous variations are possible. For example, the above technology may be applied to V-6, 1-4, 1-6, V-12, horizontally opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and of other features, functions, and / or characteristics disclosed herein.

[0064] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims are to be understood as encompassing the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements and / or properties may be claimed by amending the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal to, or different in scope from the original claims, are also considered to be encompassed within the subject matter of the present disclosure.

Claims

[1] A method for engine airflow control, wherein an engine system (200) comprises a throttle turbine generator (202) and an engine (10), wherein the throttle turbine generator (202) comprises a throttle turbine (206) that drives a turbine generator (210), wherein the throttle turbine (206) is arranged in a throttle bypass (204) around an intake throttle (62) on an intake manifold, wherein the throttle bypass (204) is configured to direct intake air from a position upstream of the intake throttle (62) to a position downstream of the intake throttle (62), the method comprising: Forward adjusting the intake throttle (62) coupled to the throttle turbine (206) based on a driver torque command (608); and further adjusting the inlet throttle (62) based on each of a first function of a pressure differential across the throttle turbine (206) and a second, different function of the pressure differential multiplied by the turbine speed, wherein adjusting the inlet throttle (62) and further adjusting the inlet throttle (62) comprises adjusting an inlet throttle angle of the inlet throttle (62). [2] The method of claim 1, wherein adjusting the inlet throttle (62) comprises adjusting an effective cross-sectional area of a restriction formed by the inlet throttle (62) on the inlet tube. [3] The method of claim 1, further comprising further adjusting the intake throttle angle based on a difference between the first function of pressure difference and a third function of pressure difference, wherein the third function of pressure difference is different from each of the first function and the second function. [4] The method of claim 3, wherein the third function is a product of each of the first function, the second function and the turbine speed. [5] The method of claim 3, wherein the effective cross-sectional area increases proportionally to the third function when the turbine speed is lower than a threshold, and wherein the effective cross-sectional area decreases proportionally to the third function when the turbine speed is higher than the threshold. [6] The method of claim 1, wherein adjusting the inlet throttle angle of the inlet throttle (62) further comprises adjusting an amount of energy generated in the turbine generator (210) coupled to the throttle turbine (206). [7] The method of claim 6, wherein adjusting the amount of energy generated in the turbine generator (210) comprises increasing an electrical power output of the turbine generator (210) under selected operating conditions. [8] The method of claim 6, further comprising charging one or more of a battery (212) and a primary generator (214) using the amount of energy generated in the turbine generator (210). [9] The method of claim 8, wherein the turbine speed is calculated based on a pulse output of the turbine generator (210). [10] A method for controlling airflow during two states, wherein the first state comprises adjusting an intake throttle angle based on a desired airflow, and the second state comprises adjusting the airflow based on the intake throttle angle, wherein an engine system (200) comprises a throttle turbine generator (202) and an engine (10), wherein the throttle turbine generator (202) comprises a throttle turbine (206) that drives a turbine generator (210), wherein the throttle turbine (206) is arranged in a throttle bypass (204) around an intake throttle (62) on an intake manifold, wherein the throttle bypass (204) is configured to direct intake air from a position upstream of the intake throttle (62) to a position downstream of the intake throttle (62), the method comprising: during the first state, adjusting an inlet throttle angle of the inlet throttle (62) coupled to the throttle turbine (206) based on each of a first function of a pressure differential across the throttle turbine (206) and a product of a second, different function of the pressure differential and the turbine speed; and during the second state, adjusting an intake airflow across the throttle turbine (206) based on each of a first function of the intake throttle angle and a product of a second, different function of the intake throttle angle and the turbine speed. [11] The method of claim 10, further comprising adjusting the inlet throttle angle of the inlet throttle (62) based on the first function when the condition of the throttle turbine (206) includes one or more of stalling or spinning below a threshold speed. [12] The method of claim 10, wherein a request for airflow control is received during the first state. [13] The method of claim 12, wherein during the first condition, the intake throttle angle is adjusted while maintaining airflow across the throttle turbine (206) and while issuing a driver torque command. [14] The method of claim 10, wherein during the first condition, adjusting the intake throttle angle comprises a forward adjustment during nominal engine operation, and further comprises a recirculation adjustment during engine idle. [15] The method of claim 10, wherein a request for an airflow estimate is received during the second state. [16] The method of claim 15, wherein during the second condition, the intake airflow across the throttle turbine (206) is adjusted while maintaining the intake throttle angle and while estimating the intake airflow into a manifold (44). [17] A system for an engine (10), wherein a throttle turbine generator (202) includes a throttle turbine (206) driving a turbine generator (210), comprising: an intake throttle (62) disposed in an intake tract (42) of the engine (10); a throttle bypass (204) configured to direct intake air from a position upstream of the intake throttle (62) to a position downstream of the intake throttle (62); one or more pressure sensors (120, 122) arranged upstream and / or downstream of the inlet throttle (62) for estimating a pressure difference across the inlet throttle (62); the throttle turbine (206) disposed in the throttle bypass (204), the throttle turbine (206) configured to drive the turbine generator (210) in electrical communication with a battery (212), the battery (212) being in further electrical communication with a primary generator (214); and a control unit (12) with computer-readable instructions stored in a non-transitory memory (106, 108) which is designed: in response to a request for setting a power of the turbine generator (210), adjust an angular position of the inlet throttle (62) based on each of a first function of a pressure differential across the throttle turbine (206) and a second, different function of the pressure differential multiplied by the turbine speed. [18] The system of claim 17, wherein the controller (12) further comprises instructions to, in response to a request for an airflow estimate, adjust an intake airflow across the throttle turbine (206) based on each of a first function of the angular position of the intake throttle (62) and a second, different function of the angular position of the intake throttle (62) multiplied by the turbine speed, wherein the turbine speed is determined based on a pulse output of the turbine generator (210).

Images