FR2886978A1 - INTERNAL COMBUSTION ENGINE AND METHOD FOR CONTROLLING A TURBINE GENERATOR IN AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

A turbine generator (turbocharger driven by an electric motor) is used to generate energy when the output torque of an internal combustion engine (1) is to be limited and comprises a turbocharger (11) having a wheel on the compressor side (11c) for compressing intake air to a cylinder (3) of the engine (1) and a turbine-side wheel (11d) to act as a turbine driven by an exhaust gas flow, the wheels on the compressor-side (11c) and turbine side (11d) being connected by a shaft (11a).

Description

1 2886978

  INTERNAL COMBUSTION ENGINE AND METHOD FOR CONTROLLING A

  TURBINE GENERATOR IN INTERNAL COMBUSTION ENGINE

  BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to an internal combustion engine comprising a mechanism for generating current by using a turbine driven by the exhaust gas (hereinafter referred to as "gas turbine"). turbine generator "). More particularly, the invention relates to a control of such a turbine generator.

  2. Description of the Related Art

  Turbocharged engines have been in use for a long time, improving intake performance by using exhaust gas. For example, Japanese Patent Application Laid-open No. 04-12131 discloses a turbocharged engine which includes a turbocharger having an electric motor which is capable of sufficiently supercharging intake air even when the engine is running at low speed. under a heavy load.

  This engine also uses the electric motor as a generator by driving it through the exhaust. That is, it drives the electric motor by rotating the turbocharger turbine using the exhaust gas, thus regenerating the power from the exhaust gas energy. The engine also includes a bypass passage in an intake passage that bypasses the compressor of the turbocharger and the valves at the compressor inlet and outlet. The amount of air passing through the compressor is adjusted by the valves to control the load of the compressor for proper use of each function, ie turbocharger boost and power generation.

  Regardless of the supercharging and power generation functions thus optimized, however, the power of the internal combustion engine must be limited to a certain level under various conditions.

  SUMMARY OF THE INVENTION In view of the above situation, the invention has been conducted to provide an internal combustion engine capable of regenerating energy from the exhaust gas through an engine. turbine generator while limiting the power of the engine as desired.

  To achieve this object, a first aspect of the invention relates to an internal combustion engine comprising a turbine generator driven by the exhaust gas of the internal combustion engine to generate current and a control means for controlling the operation of the turbine generator, which controls the operation of the turbine generator to generate current when the output torque of the internal combustion engine is to be limited.

  According to this heat engine, the turbine generator is operated to generate current when the output torque of the internal combustion engine is to be limited. As a result, the power of the motor is desirably reduced through the energy regeneration of the turbine generator.

  In the above engine, the engine power can be limited when the engine speed is in a predetermined engine speed range, which for example corresponds to a torque reduction range in which the engine power is limited to a predetermined value. This value can be a limit value of an input torque to a transmission system (i.e., transmission components such as a gearbox, a differential, a gear mechanism) connected to the transmission system. engine.

  Alternatively, the power of the heat engine can be limited in response to an engine power reduction command outputted from a vehicle behavior control system, such as a traction control system and a vehicle stability control system. vehicle that improves the stability of the vehicle through the reduction of engine power.

  Similarly, the turbine generator may be a turbocharger comprising an electric motor and the energy regeneration may be performed using the electric motor as a generator and adapted to generate electric current when it is driven by the exhaust gas of the engine. internal combustion engine.

  In this case, the execution of the regeneration of energy via the electric motor reduces the speed of the turbine and thus the intake pressure, which consequently reduces the power of the heat engine. In particular, it is possible to avoid an increase in exhaust emissions if the regeneration of energy is executed when the power of the engine must be limited to protect the transmission system since, in such a case, the engine is capable of to provide more power and is in a relatively good condition for emissions. Similarly, if the energy regeneration is performed in response to the fact that the engine power is limited to improve vehicle stability, this achieves a rapid reduction in engine power and thus early completion of the stabilization of the engine. vehicle behavior.

  A second aspect of the invention relates to a method for generating current using a turbine generator driven by the exhaust gas of an internal combustion engine. In this method, the turbine generator is operated to generate current when an output torque of the internal combustion engine is to be limited.

BRIEF DESCRIPTION OF THE DRAWINGS

  The foregoing and other objects, features, and advantages of the invention will become more apparent from the following description of the preferred embodiment with reference to the accompanying drawings in which like reference numerals are used to represent like elements and wherein: Fig. 1 is a view showing the configuration of an internal combustion engine according to an exemplary embodiment of the invention; Fig. 2 is a flowchart showing a regeneration example routine; FIG. 3 is a graph showing the performance curve of the internal combustion engine shown in FIG. 1, and FIG. 4 is a flowchart showing a further subprogram of the internal combustion engine shown in FIG. example of energy regeneration performed in the internal combustion engine shown in FIG. Figure 1.

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  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

  Hereinafter, exemplary embodiments of the invention will be described with reference to the accompanying drawings. Figure 1 is a view showing the configuration of an internal combustion engine 1 according to a first embodiment of the invention. The engine 1 is a gasoline engine of the direct injection type comprising a turbocharger driven by an electric motor 11 which serves as a generator as well as a supercharging device. It should be noted that the engine 1 can otherwise be constructed in the form of a gasoline engine of the orifice injection type or of a diesel engine.

  Engine 1 is a multi-cylinder engine although Figure 1 shows only a sectional cylinder. In each cylinder, an injector 2 directly injects fuel to the upper surface of a piston 4. Thus, the engine 1 is constructed as a so-called lean combustion engine for stratified charge combustion. The air which has been introduced via an intake passage 5 into the cylinder 3 is compressed by the piston 4 and fuel is then injected to a cavity formed on the top of the piston 4 so that a fuel-rich air-fuel mixture is formed in the vicinity of an ignition device 7, and the mixture is then ignited by the ignition device 7. As such, the engine 1 is designed to operate in one mode. of lean burning operation, using a small amount of fuel with respect to the amount of air in the combustion chamber. In addition, a turbocharger, to be described in detail later, is used to allow the introduction of a large amount of air into the combustion chamber while the engine 1 is operating in the lean burn operating mode mentioned above. above to improve fuel economy and high engine power.

  An intake valve 8 is disposed in an intake passage 5, which is open or closed to allow or close the communication between the cylinder 3 and the intake passage 5, and an exhaust valve 9 is disposed in a exhaust passage 6 which is open or closed to allow or cut the communication between the cylinder 3 and the exhaust passage 6. Along the intake passage 5 are arranged 2886978, from the upstream side, an air filter 10 , a compressor-side wheel 11c of a turbocharger unit 11, an intermediate cooling device 12, a throttle valve 13, and an intake pressure sensor 19. In addition, a wheel on the turbine side 11d of the turbocharger unit 11 and an exhaust gas catalyst 23 are arranged along the exhaust passage 6. Thus, the turbocharger unit 11 connects the intake passage 5 and the exhaust passage 6.

  The air filter 10 is used to remove impurities, for example dust from the air. The compressor side wheel lic serves as a compressor to compress the intake air, while the wheel on the turbine side lld serves as a turbine driven by an exhaust gas flow. These lic wheels 11d are connected by a shaft 11a. A rotor consisting of a permanent magnet is fixed on the shaft 11a and stators (a coil wound around an iron core) are arranged around the rotor, thus constituting a motor 11b which outputs a driving force. through the tree lia. The motor lib is an AC motor electrically connected to an inverter 21 and also serves as a generator when it is driven through the shaft 11a. The inverter 21 is electrically connected to a battery 22.

  The intermediate cooling device 12, which is an air-cooled type intermediate cooling device, is disposed downstream of the compressor side wheel lic to cool the compressed air and thus heated by the compressor-side wheel 11c. of the turbocharger unit it so that the volume of air is reduced and the efficiency of the introduction of air into each cylinder 3 improves.

  The throttle valve 13 which is an electronically controlled throttle valve driven by a throttle motor 17 is disposed downstream of the intermediate cooling device 12. A throttle sensor 18 is provided to detect the opening of the throttle valve. gas 13.

  A crankshaft sensor 26 is disposed next to the crankshaft of the engine 1 and an accelerator sensor 15 is disposed next to an accelerator pedal 14. The outputs from these sensors are inputted to a unit engine control (ECU) 16 as well as the outputs from other sensors and the like, including the throttle sensor 18, the intake pressure sensor 19 and the battery 22 (this is ie the voltage of the battery). Using these outputs, the electronic control unit 16 of the engine controls the operation of the injectors 2, the ignition devices 7, the throttle motor 17 and the inverter 21.

  In one mode of operation, the turbocharger unit 11 is only driven by the exhaust gas to supercharge the intake air just as other turbochargers usually do. In the other mode of operation, the turbocharger unit is implemented using the electric motor 11b, alone or in addition to the exhaust gas, to improve the efficiency of the supercharging. In this case, the compressor side wheel 11c and the turbine side wheel 11d are driven by the electric motor 11b. In particular, if the driver depresses the accelerator pedal, using the electric motor 11b to supercharge air advantageously reduces the time difference before the air supercharging actually starts and allows the engine speed to increase. quickly, thus improving the engine response. At the same time, it is also possible to use the engine 11b as a generator by driving the shaft 11a through the exhaust gas. The energy generated is stored in the battery 22. Thus, the motor 11b operates as regeneration energy regenerating energy from a portion of the energy of the exhaust gas.

  A more detailed explanation for energy regeneration using the engine 11b will be given below. Fig. 2 is a flowchart showing a control routine executed by the electronic control unit 16 of the engine. Fig. 3 is a graph showing a performance curve of the engine 1. Referring to Fig. 3, the torque output characteristic of the motor 1 is such that the maximum torque is obtained at approximately 2,500 rpm and the torque is reduced when the engine speed increases or decreases from this engine speed at maximum torque. The hatched area of FIG. 3 extending from 1,600 to 3,200 rpm represents a rpm region of the engine in which engine torque is restricted to 250 Nm for reasons of limited strength, durability , etc., transmission mechanisms such as a differential and a gearbox. This torque limitation is implemented by controlling the amount of fuel injection from each injector 2 according to the engine speed detected by the crankshaft sensor 26.

  The subroutine of FIG. 2 is repeatedly executed at predetermined intervals while the engine 1 is running after an engine start initiated by the electronic control unit 16 of the engine. The electronic control unit 16 of the motor first determines in step S1 whether the state intended to perform an energy regeneration has been satisfied. This state requires that the battery voltage 22 be above a predetermined level (i.e. battery 22 is in a state where it can be charged) and that the engine speed is inside. of the torque limiting region shown in FIG.

  If this condition has been satisfied, the electronic control unit 1.6 of the motor proceeds to step S3 and executes an energy regeneration (or continues the regeneration of energy if it has already been started). When starting the regeneration of energy, the electronic control unit 16 of the engine increases the amount of fuel injection so that it becomes greater than it is when the torque limitation described above is performed normally and injects the fuel into each cylinder 3 while increasing the intake amount by opening the throttle valve 13 through the throttle motor. 17. As a result, the compressor-side wheel 11c is driven by the exhaust gas flowing in the exhaust passage 6 whereby the motor 11b is rotated to generate energy corresponding to the increase. engine torque due to the increased fuel injection amount. The energy generated is then stored in the battery 22. In this regard, the inverter 21 controls the amount of energy to be generated by adjusting the rotational speed of the shaft 11a.

  According to this exemplary embodiment, it is possible to perform energy regeneration while maintaining a desired torque level so that no unintended torque change by the driver occurs.

  At the same time, it is true that the performance of the regeneration of energy reduces the speed of the turbine and thus the intake pressure, which can result in an increase in the quantity of exhaust emissions. However, in this exemplary embodiment, as the energy regeneration is performed in the torque limiting region in which the engine 1 is in a relatively good condition with respect to the amount of emissions, the amount of energy is reduced. emission does not increase beyond the amount of emissions in another speed range of the engine in which energy regeneration is not performed. As a result, the energy regeneration performance in the torque limiting region reduces an increase in emissions due to energy regeneration.

  Conversely, if it is determined in step S1 that the condition has not been satisfied, the electronic control unit 16 of the motor then proceeds to step S5 and determines whether the regeneration of energy is in progress. 'execution. If this is not the case, the motor electronic control unit 16 skips the following steps and terminates the routine, thereby maintaining a state in which the energy regeneration is not performed. If it is determined in step S5 that the energy regeneration is performed, the electronic control unit 16 of the motor then proceeds to step S7 and stops the regeneration of energy. At this time, more particularly, the electronic control unit 16 of the engine sets the fuel injection amount to the value for the normal torque limitation and resumes the normal operation of the throttle valve 13 to adjust the intake amount. .

  Since the regeneration is performed only in the torque limiting region, it causes no unwanted change in the output torque of the engine 1 and decreases an increase in the exhaust emission, whereby regeneration of energy improves and. so fuel economy.

  At the same time, the performance of the energy regeneration is not necessarily limited to this torque limiting region. For example, it may be executed when the engine output torque is to be limited in response to a command from a vehicle behavior control system.

  Fig. 4 is a flow chart showing an exemplary routine for such energy regeneration. This routine is also repeatedly executed by the electronic control unit 16 at predetermined intervals while the motor 1 rotates after the engine is started.

  Referring to Fig. 4, the engine control unit 16 of the engine determines in step S11 whether engine power reduction command has been issued from the vehicle behavior control system (for example a vehicle control system). traction control, a vehicle stability control system). If it is the case in step S11, the electronic control unit 16 of the motor goes to step S12 and determines whether the voltage of the battery 22 is below a predetermined level, namely whether the Battery 22 is in a state where it can be charged.

  If it is the case in step S12, the electronic control unit 16 of the motor then proceeds to step S13 and performs a regeneration of energy (or continues regeneration of energy if it has already been started) . At this moment, the wheel on the turbine side 11d is driven by the exhaust gas, the amount of fuel injection and the throttle angle of the gases are not changed and the shaft 11a rotates the electric motor 1lb to generate current. The energy generated is stored in the battery 22. The inverter 21 controls the amount of energy to be generated by adjusting the rotational speed of the shaft 11a and thus the proportion of reduction of the output torque of the motor.

  When the engine output torque is reduced through such energy regeneration in response to a command from the vehicle behavior control system, it makes the reduction of the torque fast and steady and allows the vehicle to operate. to be stability promptly and accurately.

  If it is determined in step S11 that no command has been issued or in step S12 that the battery voltage is sufficiently high and no load is required, the electronic control unit 16 the engine then proceeds to step S14 and determines whether an energy regeneration is currently performed. If this is the case, the motor control unit 2886978 16 of the motor goes to step S15 and stops regeneration of energy. At this time, the electronic control unit 16 of the motor commands the inverter 21 to stop the regeneration of energy and closes the throttle valve 13 by an angle corresponding to the engine torque that has been used for the regeneration of energy that has just been stopped. If it is determined in step S14 that no regeneration is performed, the electronic control unit 16 of the motor proceeds to step S15A. In this step, it is determined whether the engine power reduction command has been issued by the vehicle behavior control system. If this is not the case, the electronic control unit 16 of the motor skips the next step and ends the subprogram. If so, the electronic control unit 16 of the engine proceeds to step S16. In step S16, the engine electronic control unit 16 reduces the throttle angle of the throttle and the fuel injection amount as instructed by the vehicle behavior control system. In this way, the engine torque is reliably reduced even if no energy regeneration is performed.

  As a result, performing the torque limitation (reduction) in such an active manner enables the torque to be reduced quickly and evenly and contributes to improving the stability of the vehicle.

  Although the shaft 11a serves as both the input / output shaft of the engine 11b and the compressor side wheel rotation shaft 11c and the turbocharger unit 11 in the exemplary embodiment Previously, such shafts can be supplied separately and connected via a reduction mechanism (for example a reduction gear mechanism).

  Likewise, although the invention has been applied to a turbocharger driven by an electric motor in the above exemplary embodiment, it can also be applied to a turbine generator that generates energy using energy. (the flow) of exhaust gas, for example.

  Also, although the energy regeneration is performed only when the power of the motor is to be limited in the exemplary embodiment, the energy regeneration can be performed as long as the battery needs to be charged. even if a reduction in engine power is not required.

  Although the invention has been described with reference to its preferred embodiments, it should be understood that the invention is not limited to the preferred embodiments or designs. On the contrary, it is intended that the intention covers various modifications and equivalent arrangements other than those described above. Furthermore, although the various elements of the preferred embodiments are represented in various combinations and configurations, which are exemplary, other combinations and configurations comprising more or fewer elements, or only a single element are also in the spirit. and the scope of the invention.

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Claims (14)

  An internal combustion engine (1) comprising a turbine generator (11) driven by the exhaust gas of the internal combustion engine (1) for generating energy and control means (16) for controlling the combustion engine. operation of the turbine generator (11), wherein: the control means (16) controls the operation of the turbine generator (11) to generate energy when an output torque of the internal combustion engine (1) ) should be limited, said internal combustion engine being characterized in that: said turbine generator (11) comprises a turbocharger (11) having a compressor-side wheel (11c) for compressing intake air to a cylinder (3) of the internal combustion engine (1) and a turbine-side wheel (11d) to act as a turbine driven by an exhaust gas flow, said compressor-side wheel (11c) and said turbine-side wheel (11d). ) being connected by a tree (1 1a).   The internal combustion engine (1) according to claim 1, wherein a motor (11b) is provided between said compressor-side wheel (11c) and said turbine-side wheel (11d) so as to generate energy electric when it is driven by the exhaust gas of the internal combustion engine (1) by means of said shaft (11a).   13 2886978 3. The internal combustion engine (1) according to claim 1 or 2, wherein the output torque of the internal combustion engine (1) is limited when the engine speed of the engine of the internal combustion engine (1) is in a range. predetermined engine speeds.   The internal combustion engine (1) according to claim 3, wherein the predetermined engine speed range corresponds to a torque reduction range in which the output torque of the internal combustion engine (1) is limited to one. predetermined value or at a value lower than this.   The internal combustion engine (1) according to claim 4, wherein the predetermined value is an input torque limit value applied to a transmission system connected to the internal combustion engine (1).   The internal combustion engine (1) according to claim 1 or 2, wherein the output torque of the internal combustion engine (1) is limited in response to a motor power reduction command transmitted from a motor means. control of vehicle behavior.   The internal combustion engine (1) according to claim 1 or 2, wherein the output torque of the internal combustion engine (1) is limited in response to a torque restriction control which controls an amount of torque. injecting fuel from the internal combustion engine so as to limit the output torque of the internal combustion engine (1), and when the torque restriction control is to be executed, the control means (16) increases the injection quantity of fuel compared to that normally in a torque restriction control and controls the turbine generator (11) to generate a quantity of energy corresponding to an increase in the output torque of the internal combustion engine ( 1) resulting from the increase in the amount of fuel injection.   A method of generating energy using a turbine generator (11) driven by the exhaust gas of an internal combustion engine (1), comprising: controlling the operation of the turbine generator (11) to generate energy when the output torque of the internal combustion engine is to be limited, characterized by: compressing the intake air to a cylinder (3) of the internal combustion engine (1) by means of a wheel on the compressor side (11c) of a turbocharger of said turbine generator (11) and the use of a turbine-side wheel (11d) as a turbine driven by a circulation of exhaust gas, said compressor-side wheel (11c) ) and said turbine-side wheel (11d) being connected by a shaft (11a).   2886978 The energy generating method according to claim 8, further comprising generating electric power by means of a motor (11b) provided between said compressor-side wheel (11c) and said turbine-side wheel (11d). ), said motor (11b) being driven by the exhaust gas of the internal combustion engine (1) by means of said shaft (11a).   The energy generating method according to claim 8 or 9, wherein the output torque of the internal combustion engine (1) is to be limited when the engine speed of the internal combustion engine (1) is in a range. predetermined engine speeds.   The power generating method according to claim 10, wherein the predetermined motor speed range corresponds to a torque reduction range in which the output torque of the internal combustion engine (1) is to be limited to one. predetermined value or at a value lower than this.   The energy generating method according to claim 11, wherein the predetermined value is an input torque limit value applied to a transmission system connected to the internal combustion engine.   16 2886978 The energy generating method according to claim 8 or 9, wherein the output torque of the internal combustion engine (1) is to be limited in response to an engine power reduction command outputted from an ignition means. control of vehicle behavior.   The energy generating method according to claim 8 or 9, wherein the output torque of the internal combustion engine (1) is limited in response to a torque restriction command that controls a fuel injection amount. of the internal combustion engine so as to limit the output torque of the internal combustion engine (1), and when the torque restriction control is to be executed, the control means (16) increases the amount of fuel injection by to that which is normally in a torque restriction control and controls the turbine generator (11) to generate an amount of energy corresponding to an increase in the output torque of the resultant internal combustion engine (1). of increasing the amount of fuel injection.