JP2022018212A - Engine system - Google Patents

Abstract

To make fuel consumption performance and exhaust emission control performance compatible.SOLUTION: An engine system is equipped with an internal combustion engine 10, a gas turbine engine 40 that has turbines 46, 47, and 48, compressors 42, 43, and 44, and a coupling shaft 49, an electric generator 75 that is provided on the coupling shaft 49, a combustor 70, an injector 71 that can inject fuel into the combustor 70, an exhaust aftertreatment device 50, and a control portion 100. The control portion 100 controls the operation of the internal combustion engine 10 in a lean combustion mode, and injects fuel from the injector 71 into the combustor 70 to burn, thereby raising the temperature of exhaust flowing in the turbines 46, 47, and 48 and lowering the oxygen concentration of the exhaust flowing in the exhaust aftertreatment device 50.SELECTED DRAWING: Figure 1

Description

This disclosure relates to an engine system.

As an exhaust aftertreatment device, it is equipped with a three-way catalyst that purifies CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) in the exhaust with high efficiency when the exhaust is near the stoichiometric air-fuel ratio. Is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-145111

Since the three-way catalyst can exhibit highly efficient purification performance near the stoichiometric air-fuel ratio, it is said that the desired purification performance cannot be exhibited in a diesel engine or the like that is operated by combustion on the lean side of the stoichiometric air-fuel ratio. There are challenges. On the other hand, if the diesel engine is burnt stoichiometrically in the vicinity of the stoichiometric air-fuel ratio in order to ensure the purification performance of the exhaust gas, there is a problem that the desired fuel efficiency performance cannot be obtained. Therefore, it is desired to provide an engine system capable of achieving both the purification performance of these exhaust gases and the fuel efficiency performance.

The technique of the present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide an engine system capable of achieving both fuel efficiency performance and exhaust gas purification performance.

The engine system of the present disclosure includes an internal combustion engine, a turbine provided in the exhaust system of the internal combustion engine, a compressor provided in the intake system of the internal combustion engine, and a gas having a connecting shaft connecting the turbine and the compressor. From the turbine engine, the electric generator provided on the connecting shaft, the combustor provided in the exhaust system on the upstream side of the turbine, the injector capable of injecting fuel into the combustor, and the turbine. Also includes an exhaust aftertreatment device provided in the exhaust system on the downstream side, a control unit for controlling the operation of the internal combustion engine and fuel injection of the injector, and the control unit operates the internal combustion engine. By controlling in the lean combustion mode and injecting fuel from the injector into the combustor to burn the fuel, the temperature of the exhaust flowing into the turbine rises above the temperature of the exhaust discharged from the internal combustion engine. It is characterized in that the oxygen concentration of the exhaust flowing into the exhaust aftertreatment device is reduced.

Further, an intake throttle valve capable of adjusting the flow rate of the intake air flowing through the intake system and an exhaust gas recirculation device for recirculating the exhaust gas flowing through the exhaust system to the intake system are further provided, and the control unit is provided with the control unit. When the operating state of the internal combustion engine becomes a predetermined low load operating region, the intake throttle valve and / or the exhaust gas recirculation device are operated so that the excess air ratio of the exhaust becomes equal to or less than the predetermined upper limit air excess ratio. It is preferable to control it.

Further, the exhaust aftertreatment device is provided with a three-way catalyst, and outputs a value according to the oxygen concentration of the exhaust to the exhaust system on the downstream side of the combustor and on the upstream side of the three-way catalyst. A possible exhaust sensor is provided, and it is preferable that the control unit controls the fuel injection amount of the injector so that the oxygen concentration of the exhaust becomes 0 based on the output value of the exhaust sensor.

Further, it is preferable that the exhaust aftertreatment device includes an oxidation catalyst, a filter, and a selective reduction catalyst in this order from the exhaust upstream side.

Further, the intake system on the downstream side of the compressor is provided with an intake sensor capable of outputting the actual boost pressure according to the pressure of the intake air pressured by the compressor, and the control unit is the internal combustion engine. When the actual boost pressure is lower than the target boost pressure set based on the operating state of, the electric generator is driven as an electric motor, and the actual boost pressure is relative to the target boost pressure. When is high, it is preferable to drive the electric generator as a generator.

Further, an intake bypass passage that bypasses the intake air flowing through the intake system from the compressor, an intake bypass valve that can adjust the flow rate of the intake air flowing through the intake bypass passage, and an exhaust that bypasses the exhaust flowing through the exhaust system from the turbine. A bypass passage and an exhaust bypass valve capable of adjusting the flow rate of the exhaust flowing through the exhaust bypass passage are further provided, and the control unit is described when the operating state of the internal combustion engine becomes a predetermined low load operating region. It is preferable to control the opening degree of the intake bypass valve and the exhaust bypass valve to the open side.

According to the engine system of the present disclosure, both fuel efficiency performance and exhaust gas purification performance can be achieved at the same time.

It is a schematic whole block diagram of the engine system which concerns on 1st Embodiment. It is a schematic functional block diagram which shows the control apparatus which concerns on 1st Embodiment, and the related peripheral configurations. It is a flowchart explaining the flow of control of the engine system which concerns on 1st Embodiment. It is a schematic whole block diagram of the engine system which concerns on 2nd Embodiment. It is a schematic functional block diagram which shows the control apparatus which concerns on 2nd Embodiment, and the related peripheral configurations. It is a schematic whole block diagram of the engine system which concerns on 3rd Embodiment. It is a schematic whole block diagram of the engine system which concerns on other embodiment.

Hereinafter, the engine system according to the present embodiment will be described with reference to the attached drawings. The same parts are designated by the same reference numerals, and their names and functions are also the same. Therefore, detailed explanations about them will not be repeated.

[First Embodiment]
FIG. 1 is a schematic overall configuration diagram of the engine system 1A according to the first embodiment.

As shown in FIG. 1, the engine system 1A is mounted on, for example, a vehicle V, and mainly includes an engine 10 as an internal combustion engine, a gas turbine engine 40, a combustor 70 having an injector 71, and a gas turbine engine. It is equipped with an electric generator 75 provided in 40.

Specifically, the engine system 1A makes the exhaust of the engine 10 in a higher temperature state by burning the fuel injected from the injector 71 in the combustor 70, and uses the exhaust in the high temperature state to make the gas turbine engine 40 highly efficient. A so-called combined cycle is configured in which the surplus exhaust energy generated in the combustor 70 is recovered by generating the surplus exhaust energy generated in the combustor 70 by the electric generator 75 while sending the compressed intake air to the engine 10.

The engine 10 is, for example, a diesel engine that uses light oil as fuel, and includes an engine main body 11 that mainly includes a cylinder head, a cylinder block, and the like. The cylinder block of the engine main body 11 is provided with a plurality of cylinders (hereinafter, also referred to as cylinders) C for accommodating pistons (not shown) so as to be reciprocating. A crankshaft CS is connected to the piston via a connecting rod, a crank arm, etc. (neither is shown), and the reciprocating motion of the piston is converted into rotary motion and transmitted to the crankshaft CS. ing.

The engine 10 is not limited to the in-line multi-cylinder engine shown in the illustrated example, and may be a single-cylinder engine, a V-type engine, a horizontally opposed engine, or the like. Further, the engine 10 is not limited to a diesel engine, and may be another internal combustion engine such as a gasoline engine or a natural gas engine.

A motor 14, a transmission 15 and the like are connected to the crankshaft CS via a clutch device 13. Further, the left and right drive wheels 19L and 19R are connected to the transmission 15 via a propeller shaft 16, a differential device 17, left and right drive shafts 18L and 18R, and the like, respectively. The vehicle V is not limited to the rear-wheel drive vehicle of the illustrated example, and may be a front-wheel drive vehicle, a four-wheel drive vehicle, or the like. Further, although the motor 14 is arranged on the downstream side of the clutch device 13, the motor 14 may be arranged on the upstream side of the clutch device 13. Further, the vehicle V is not limited to the parallel type hybrid vehicle of the illustrated example, and may be a series type or a series / parallel type hybrid vehicle in which the motors 14 are arranged on the upstream and downstream sides of the clutch device 13. If it is a series type, steady operation that effectively suppresses the load fluctuation of the engine 10 becomes possible.

The motor 14 is power-driven as an electric motor by the electric power supplied from the vehicle-mounted battery 78 via the inverter 79 when the vehicle V is accelerating, and is generated and driven as a generator when the vehicle V is decelerating. The regenerative power generated by the motor 14 is stored in the vehicle-mounted battery 78 according to the remaining charge capacity of the vehicle-mounted battery 78, or is supplied to auxiliary equipment, electrical components, etc. (not shown).

The arrangement configuration of the motor 14 is not limited to the illustrated example, and may be connected to the transmission 15 via a PTO (Power-Take-Off) device or the like. Further, the vehicle V is not limited to the hybrid vehicle including the engine 10 and the motor 14 in the illustrated example, and may be an engine vehicle having only the engine 10 as a driving force source.

The cylinder head of the engine body 11 is provided with an in-cylinder injector 12 for injecting fuel into each cylinder C. The fuel injection amount and injection timing of each in-cylinder injection 12 are appropriately controlled according to a command transmitted from the control device 100 based on a required load and the like. The engine 10 is not limited to the direct injection engine, and may be a premixed engine.

On the side of the cylinder head of the engine body 11, an intake manifold 20 (a part of the intake system) that distributes the intake air to each intake port and an exhaust manifold 30 (a part of the exhaust system) that collects exhaust from each exhaust port. ) Is attached.

The intake passage 21 (intake system of the present disclosure) of the engine 10 is connected to the intake manifold 20, and the exhaust passage 31 (exhaust system of the present disclosure) of the engine 10 is connected to the exhaust manifold 30. Further, the intake manifold 20 is provided with a boost pressure sensor 90 (an example of the intake sensor of the present disclosure) capable of acquiring an actual boost pressure _{BP_Act} corresponding to the pressure of the intake air pressured by the gas turbine engine 40. ..

The intake passage 21 includes an upstream intake passage 22, a compressor passage 41, and a downstream intake passage 23 in this order from the intake upstream side. In the present embodiment, the boost pressure sensor 90 is provided in the intake manifold 20, but may be provided in the downstream intake passage 23.

An air cleaner 24 for filtering foreign matter is provided at the upstream end (inlet end) of the upstream intake passage 22. Further, an intake air flow rate sensor 91 that acquires an intake air flow rate MAF is provided in the upstream intake passage 22 located immediately downstream of the air cleaner 24.

A plurality of compressors 42, 43, 44 forming a part of the gas turbine engine 40 are sequentially provided in the compressor passage 41. Specifically, the compressor passage 41 includes an upstream compressor passage 41A that sends compressed intake air from the first compressor 42 to the second compressor 43, and a downstream compressor passage 41B that sends compressed intake air from the second compressor 43 to the third compressor 44. I have. Although detailed illustration is omitted, a cooler capable of cooling the compressed intake air may be provided between the compressors 42, 43, and 44 of the compressor passage 41.

The downstream intake passage 23 is provided with an intercooler 25 for cooling the compressed intake air pumped by the compressors 42, 43, 44. The intercooler 25 may be either an air-cooled type or a water-cooled type. Further, the downstream intake passage 23 is provided with an intake throttle valve 26 capable of adjusting the flow rate of the intake air. The opening degree of the intake throttle valve 26 is appropriately controlled according to a command transmitted from the control device 100 based on the operating state of the engine 10 and the like.

The exhaust passage 31 includes an upstream exhaust passage 32, a turbine passage 45, and a downstream exhaust passage 33 in this order from the exhaust upstream side.

The upstream exhaust passage 32 connects the exhaust collecting portion of the exhaust manifold 30 and the upstream end (inlet) of the turbine passage 45. A combustor 70, which will be described in detail later, is provided at a predetermined position in the upstream exhaust passage 32. In the illustrated example, the combustor 70 is provided at a substantially intermediate portion of the upstream exhaust passage 32, but may be provided immediately upstream of the turbine passage 45. If it is provided directly upstream of the turbine passage 45, the heat generated by the combustor 70 can be efficiently transferred to the turbines 46, 47, 48. Although not shown, an exhaust temperature sensor may be provided in the upstream exhaust passage 32 on the upstream side of the combustor 70.

A plurality of turbines 46, 47, 48 forming a part of the gas turbine engine 40 are sequentially provided in the turbine passage 45. Specifically, the turbine passage 45 includes an upstream turbine passage 45A that sends the exhaust gas that has flowed through the first turbine 46 to the second turbine 47 and a downstream turbine passage 45B that sends the exhaust gas that has flowed through the second turbine 47 to the third turbine 48. And have.

The downstream exhaust passage 33 is provided with a three-way catalyst 50 as an example of an exhaust aftertreatment device. The three-way catalyst 50 has a function of simultaneously purifying CO, HC, and NOx in the exhaust gas with high efficiency when the exhaust gas is near the stoichiometric air-fuel ratio. In the downstream exhaust passage 33 on the upstream side of the three-way catalyst 50, a NOx / lambda sensor 92 (an example of the exhaust sensor of the present disclosure) for acquiring a NOx value and a lambda value (hereinafter, also referred to as an excess air ratio) of the exhaust is provided. It is provided. As the NOx / lambda sensor 92, another sensor may be used as long as it can transmit an output value according to the oxygen concentration of the exhaust gas. Further, the NOx / lambda sensor 92 may be provided in the upstream exhaust passage 32 on the downstream side of the combustor 70, for example, as long as it is on the exhaust upstream side of the three-way catalyst 50.

The exhaust gas recirculation system (hereinafter referred to as EGR device) 60 includes an EGR passage 61 that recirculates at least a part of the exhaust gas of the engine 10 to the intake system, and an air-cooled or water-cooled EGR that cools the EGR gas. It includes a cooler 62 and an EGR valve 63 that adjusts the EGR rate. The opening degree of the EGR valve 63 is appropriately controlled according to a command transmitted from the control device 100 based on the operating state of the engine 10 and the like.

The EGR device 60 is a so-called high-pressure EGR device, and recirculates the exhaust gas taken out from the exhaust passage 31 on the upstream side of the gas turbine engine 40 to the intake passage 21 on the downstream side of the gas turbine engine 40. In the illustrated example, the EGR passage 61 is branched from the exhaust manifold 30, but may be branched from the upstream exhaust passage 32 on the upstream side of the combustor 70. Further, although the EGR passage 61 joins the downstream intake passage 23 on the downstream side of the intake throttle valve 26, it may join the intake manifold 20 directly. The EGR device 60 is not limited to the high-pressure EGR device, and may be a low-pressure EGR device.

The gas turbine engine 40 includes a plurality of turbines 46, 47, 48 driven by exhaust gas (three in the illustrated example), a plurality of compressors 42, 43, 44 for compressing intake air (three in the illustrated example), and these turbines. It is provided with 46, 47, 48 and a connecting shaft 49 connecting the compressors 42, 43, 44. Further, a motor generator 75 is provided between the turbines 46, 47, 48 of the connecting shaft 49 and the compressors 42, 43, 44. The power generated by the motor generator 75 may be stored in the vehicle-mounted battery 78 depending on the remaining charge capacity of the vehicle-mounted battery 78, or may be supplied to the motor 14 such as auxiliary equipment and electrical components (not shown). do. The number of compressors and turbines is not limited to 3 in each of the illustrated examples, and may be 1 in each, 2 in each, or 4 or more in each.

The combustor 70 is provided with an injector 71 capable of injecting fuel (for example, light oil) into the combustor 70. The fuel injection amount of the injector 71 is appropriately controlled in response to a command from the control device 100. The combustor 70 sends oxygen remaining in the high-temperature exhaust gas discharged from the engine 10 to the turbines 46, 47, 48 on the downstream side by mixing and burning the fuel injected from the injector 71. It functions to further raise the temperature of the exhaust gas to be produced and to effectively reduce the exhaust gas flowing into the three-way catalyst 50 to the vicinity of the stoichiometric air-fuel ratio (stoichi).

In addition to the boost pressure sensor 90, intake air flow rate sensor 91, and NOx / lambda sensor 92 described above, the engine system 1A is provided with various sensors such as an engine rotation speed sensor 93, an accelerator opening sensor 94, and a vehicle speed sensor 95. Has been done. The engine speed sensor 93 acquires the engine speed Ne from the crankshaft CS (or flywheel). The accelerator opening sensor 94 acquires the accelerator opening Ac according to the amount of depression of the accelerator pedal 98. The vehicle speed sensor 95 acquires the vehicle speed of the vehicle V from the propeller shaft 16 and the like. The detection signals of each of these sensors 90 to 95 are transmitted to the electrically connected control device 100.

[Control device]
FIG. 2 is a schematic functional block diagram showing a control device 100 according to the present embodiment and related peripheral configurations.

The control device 100 is, for example, a device that performs calculations such as a computer, and is a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, and an output port connected to each other by a bus or the like. And so on, run the program.

Further, the control device 100 functions as a device including an engine control unit 110, an exhaust combustion control unit 120, a motor generator control unit 130, and a low load air amount control unit 140 by executing a program. Each of these functional elements will be described as being included in the control device 100, which is integrated hardware in the present embodiment, but any part of these may be provided in separate hardware.

The engine control unit 110 performs engine control that controls the fuel injection amount and injection timing of the in-cylinder injector 12 according to the required load acquired by the accelerator opening sensor 94 or the like. In the present embodiment, the engine control unit 110 controls the fuel injection of each in-cylinder injector 12 in a so-called lean combustion mode in which each cylinder C of the engine 10 is burned with an air-fuel mixture thinner than the stoichiometric air-fuel ratio. In this way, by lean-burning each cylinder C of the engine 10 to increase the thermal efficiency, the fuel efficiency performance of the engine 10 is surely improved.

The exhaust combustion control unit 120 controls the fuel injection amount of the injector 71 to burn the oxygen remaining in the exhaust gas discharged from the engine 10 and implement the exhaust combustion control to further raise the temperature of the exhaust gas. Specifically, the injection amount map M1 created in advance by an experiment or the like is stored in the memory of the control device 100. In this injection amount map M1, the excess air ratio (lambda value) of the exhaust gas, the outlet exhaust gas temperature of the engine 10, and the fuel required to burn the oxygen remaining in the exhaust gas to make the oxygen concentration of the exhaust gas substantially 0. The relationship with the injection amount (target injection amount) of is specified. The target injection amount is set to increase, for example, as the excess air ratio of the exhaust increases.

The exhaust combustion control unit 120 injects based on the lambda value of the exhaust acquired by the NOx / lambda sensor 92 and the outlet exhaust temperature of the engine 10 estimated from the sensor values of various sensors 90, 91, 93, 94 and the like. By referring to the quantity map M1, the target injection amount of the injector 71 is set, and the instruction signal of the set target injection amount is sequentially transmitted to the injector 71.

In this way, when exhaust gas combustion control is performed in which fuel is injected into the exhaust gas flowing into the combustor 70 and the exhaust gas is burned to further raise the temperature of the exhaust gas, the temperature is higher than the outlet exhaust gas temperature of the engine 10. Exhaust gas flows into the turbines 46, 47, 48, and it is possible to surely improve the drive efficiency (intake supercharging efficiency) of the gas turbine engine 40. In addition, exhaust gas equivalent to the stoichiometric air-fuel ratio (stoichi) in which almost no oxygen remains flows into the three-way catalyst 50 on the downstream side, and the purification performance of CO, HC, and NOx of the three-way catalyst 50 is surely improved. It is also possible.

The motor generator control unit 130 implements drive control for controlling the drive of the motor generator 75 according to the operating state of the engine 10. Specifically, the memory of the control device 100 stores a boost pressure map M2 that defines the relationship between the operating state of the engine 10 and the target boost pressure _{BP_Tag} created in advance.

The motor generator control unit 130 first refers to the boost pressure map M2 based on the operating state of the engine 10 acquired by the engine rotation speed sensor 93, the accelerator opening sensor 94, etc., and thereby the target boost pressure BP. Set _{_Tag} . Further, the motor generator control unit 130 compares the set target boost pressure BP _{_Tag} with the actual boost pressure BP _{_Act} acquired by the boost pressure sensor 90, and the actual boost pressure BP _{_Act} is the target boost pressure. If it is lower than BP _{_Tag} (BP _{_Act} <BP _{_Tag} ), power is supplied from the in-vehicle battery 78 to the electric generator 75, and the electric generator 75 is driven as an electric motor to drive the compressed air by the compressors 42, 43, 44. Increase the amount of pumping. The amount of power supplied from the vehicle-mounted battery 78 may be feedback-controlled, for example, based on the deviation between the actual boost pressure BP _{_Act} and the target boost pressure BP _{_Tag} .

On the other hand, if the actual boost pressure BP _{_Act} is higher than the target boost pressure BP _{_Tag} (BP _{_Act} > BP _{_Tag} ), the motor generator control unit 130 drives the motor generator 75 as a generator to make a compressor. The amount of compressed air pumped by 42, 43, 44 is reduced. The amount of power generated by the motor generator 75 may be, for example, feedback controlled based on the deviation between the actual boost pressure BP _{_Act} and the target boost pressure BP _{_Tag} .

In this way, when the actual boost pressure BP _{_Act} is higher than the target boost pressure BP _{_Tag} , the injector 71 recovers the surplus exhaust energy generated in the combustor 70 as electric power by the motor generator 75. It becomes possible to effectively prevent the fuel consumption of the engine from being wasted. The electric power generated by the motor generator 75 may be stored in the vehicle-mounted battery 78 according to the remaining charge capacity, or may be supplied to the traveling motor 14 according to the required load or the like. When the actual boost pressure BP _{_Act} is substantially equal to the target boost pressure BP _{_Tag} (BP _{_Act} = BP _{_Tag} ), the motor generator 75 may be switched to the no-load state.

The low load air amount control unit 140 implements air amount reduction control that effectively reduces the oxygen amount of the exhaust gas during the low load operation of the engine 10 in which the excess air ratio of the exhaust gas is high. Specifically, the low load air volume control unit 140 takes in the intake throttle valve 26 when the operating state of the engine 10 acquired by the engine rotation speed sensor 93, the accelerator opening sensor 94, or the like becomes a predetermined low load operating region. By narrowing the opening of the EGR valve 63 to the closed side to reduce the amount of intake air, or by controlling the opening of the EGR valve 63 to the open side to increase the EGR rate, the excess air rate of the exhaust is effectively reduced. Let me.

The opening degree control of the intake throttle valve 26 and the EGR valve 63 may be selectively executed by only one of them, or both of them may be executed in parallel. The opening degree of each of the valves 26 and 63 may be feedback-controlled so that the excess air ratio of the exhaust gas flowing into the combustor 70 is within a predetermined range. Here, the excess air ratio of the exhaust gas may be acquired by the NOx / lambda sensor 92. Further, the lower limit of the excess air rate may be based on a value that can suppress excessive deterioration of combustion stability due to a decrease in thermal efficiency and an excessive increase in black smoke emission, and the upper limit of the excess air rate is set. For example, the upper limit injection amount of the injector 71 may be set as a reference.

In this way, during low load operation of the engine 10 in which the excess air ratio of the exhaust is high, the exhaust flowing into the combustor 70 is controlled by reducing the intake air flow rate or increasing the EGR ratio. It becomes possible to effectively reduce the excess air ratio, and it is possible to effectively prevent the amount of fuel injection of the injector 71 from becoming excessive.

The method of air volume reduction control is not limited to the opening control of the intake throttle valve 26 and the EGR valve 63, and if the engine 10 is provided with a variable valve mechanism, a cylinder deactivation mechanism, or the like, any cylinder can be used. The valve opening / closing timing may be changed, or the operation of any cylinder may be selectively suspended.

Next, the flow of control of the engine system 1A according to the present embodiment will be described with reference to FIG. This routine is preferably started at the same time as the engine 10 is started (ignition ON) and ends when the engine 10 is stopped (ignition OFF).

In step S100, the fuel injection of each in-cylinder injector 12 is controlled in a lean combustion mode in which each cylinder C of the engine 10 is burned with an air-fuel mixture thinner than the stoichiometric air-fuel ratio.

Next, in step S110, it is determined whether or not the operating state of the engine 10 is in a predetermined low load operating region. If it is in the low load operation region (Yes), this control proceeds to step S120. On the other hand, if it is not in the low load operation region (No), this control proceeds to step S130. In step S120, the air amount reduction control is executed so that the excess air rate of the exhaust gas flowing from the engine 10 into the combustor 70 is set to be equal to or less than the predetermined upper limit air excess rate.

In step S130, fuel is injected from the injector 71 into the combustor 70, and exhaust combustion control is performed to burn the oxygen remaining in the exhaust gas to further raise the temperature of the exhaust gas. As a result, high-temperature exhaust gas having a temperature higher than the outlet exhaust gas temperature of the engine 10 flows into the turbines 46, 47, and 48, and the drive efficiency of the gas turbine engine 40 can be reliably improved. Further, the exhaust gas corresponding to the stoichiometric air-fuel ratio in which almost no oxygen remains flows into the three-way catalyst 50, and it is possible to surely improve the purification performance of CO, HC and NOx by the three-way catalyst 50.

In step S140, it is determined whether or not the actual boost pressure BP _{_Act} is higher than the target boost pressure BP _{_Tag} . When the actual boost pressure BP _{_Act} is higher than the target boost pressure BP _{_Tag} (Yes), the process proceeds to step S150, and the motor generator 75 is driven as a generator, so that the surplus exhaust energy generated by the combustor 70 is generated. Is recovered as electric power. On the other hand, when the actual boost pressure BP _{_Act} is lower than the target boost pressure BP _{_Tag} (No), the process proceeds to step S160, and the motor generator 75 is driven as a motor to compress the air by the compressors 42, 43, 44. Increase the amount of pumping. After that, each of the above steps S100 to 160 is repeatedly executed until the engine 10 is stopped.

According to the present embodiment described in detail above, the engine system 1A includes an engine 10 as an internal combustion engine, a gas turbine engine 40 driven by the exhaust of the engine 10, a combustor 70 having an injector 71, and a gas turbine engine 40. It is equipped with an electric generator 75 provided in the above. In the engine system 1A, while the engine 10 is operated in the lean combustion mode, the amount of fuel that burns the oxygen remaining in the exhaust gas is injected from the injector 71 into the combustor 70 to the three-way catalyst 50 on the downstream side. It is configured to supply exhaust equivalent to the stoichiometric air-fuel ratio. As a result, while operating the engine 10 with high efficiency, the three-way catalyst 50 can simultaneously purify CO, HC, and NOx in the exhaust with high efficiency, achieving both improvement in fuel efficiency and improvement in exhaust purification performance. It becomes possible to plan.

[Second Embodiment]
Next, the details of the engine system 1B according to the second embodiment will be described with reference to FIGS. 4 and 5.

FIG. 4 is a schematic overall configuration diagram showing the engine system 1B of the second embodiment, and FIG. 5 is a schematic functional block diagram showing the control device 100 of the second embodiment and related peripheral configurations. be.

In the engine system 1B of the second embodiment, bypass passages 81, 82, 85, 86 are added to the engine system 1A of the first embodiment, and a valve control unit 150 is added as a functional element of the control device 100. Is. Since other configurations are the same as those in the first embodiment, detailed description thereof will be omitted.

As shown in FIG. 4, the first intake bypass passage 81 connects the upstream intake passage 22 and the upstream compressor passage 41A, and detours the flow of intake air from the first compressor 42. The first intake bypass passage 81 is provided with a first intake bypass valve 83 capable of linearly adjusting the opening degree of the passage. The first intake bypass valve 83 may be an ON / OFF valve.

The second intake bypass passage 82 connects the upstream intake passage 22 and the downstream compressor passage 41B, and detours the flow of intake air from the first compressor 42 and the second compressor 43. The second intake bypass passage 82 is provided with a second intake bypass valve 84 capable of linearly adjusting the opening degree of the passage. The second intake bypass valve 84 may be an ON / OFF valve.

The first exhaust bypass passage 85 connects the upstream turbine passage 45A and the downstream exhaust passage 33, and detours the exhaust flow from the second turbine 47 and the second turbine 48. The first exhaust bypass passage 85 is provided with a first exhaust bypass valve 87 capable of linearly adjusting the opening degree of the passage. The first exhaust bypass valve 87 may be an ON / OFF valve.

The second exhaust bypass passage 86 connects the downstream turbine passage 45B and the downstream exhaust passage 33, and detours the exhaust flow from the third turbine 48. The second exhaust bypass passage 86 is provided with a second exhaust bypass valve 88 capable of linearly adjusting the opening degree of the passage. The second exhaust bypass valve 88 may be an ON / OFF valve.

The valve control unit 150 shown in FIG. 5 appropriately adjusts the opening degrees of the bypass valves 83, 84, 87, 88 based on the operating state of the engine 10 acquired by the engine rotation speed sensor 93, the accelerator opening sensor 94, and the like. To control. Specifically, when the operating state of the engine 10 is in the predetermined low load operating region, the valve control unit 150 increases the flow rate of the intake air passing through the compressors 42, 43, 44 as the load of the engine 10 decreases. The opening degree of each bypass valve 83, 84, 87, 88 is controlled to the open side so that the flow rate of the exhaust gas passing through the turbines 46, 47, 48 is reduced. Here, the valve opening degree control may be performed by referring to the target boost pressure map that defines the relationship between the operating state (rotation speed, accelerator opening degree, etc.) of the engine 10 and the target boost pressure. During the execution of the valve opening degree control, the motor generator 75 is subjected to the rotation speed control so as to output the target rotation speed according to the target boost pressure. In this way, when the load of the engine 10 where the amount of air is low is low, the intake and exhaust are bypassed from the gas turbine engine 40. It is possible to effectively maintain the proper pressure ratios of the compressors 42, 43, 44 and the turbines 46, 47, 48.

The configuration of the bypass passages 81, 82, 85, 86 is not limited to the illustrated example, and the third intake bypass passage (upstream intake passage 22) that completely bypasses the compressors 42, 43, 44 and the turbines 46, 47, 48. And the downstream side intake passage 23) and a fourth exhaust bypass passage (connecting the upstream side exhaust passage 32 and the downstream side exhaust passage 33) may be further provided. If the fourth exhaust bypass passage is provided, it becomes possible to appropriately perform bypass control of the turbines 46, 47, 48 such as a supercharger with a wastegate valve. Further, instead of these exhaust bypass passages, at least one of the turbines 46, 47, 48 can be configured as a variable capacity turbo equipped with variable wings.

[Third Embodiment]
Next, the details of the engine system 1C according to the third embodiment will be described with reference to FIG.

FIG. 6 is a schematic overall configuration diagram showing the engine system 1C of the third embodiment. In the engine system 1C of the third embodiment, as an exhaust aftertreatment device, an oxidation catalyst 51, a filter 52, a urea water injector 53, and a selective reduction catalyst (Selective Catalytic Reduction: hereinafter, in order) are provided in the downstream exhaust passage 33 from the upstream side. It is provided with an SCR catalyst) 54 and an ammonia slip catalyst 55. Since other configurations are the same as those in the first embodiment, detailed description thereof will be omitted.

The oxidation catalyst 51 is formed by supporting an oxidation catalyst component or the like on the surface of a ceramic carrier such as a cordierite honeycomb structure, and oxidizes HC and CO contained in the exhaust gas. When unburned fuel is supplied by the post injection of the engine 10 or the exhaust pipe injection of the injector 71, the oxidation catalyst 51 oxidizes the unburned fuel to raise the exhaust temperature.

The filter 52 is formed, for example, by arranging a large number of cells partitioned by a porous partition wall along the flow direction of exhaust gas and alternately sealing the upstream side and the downstream side of these cells. , Particulate Matter (PM) in the exhaust gas is collected in the pores and surface of the partition wall. The filter 52 is periodically regenerated by burning and removing the accumulated PM. In the filter regeneration, the PM accumulation amount of the filter 52 reaches a predetermined amount, the front-rear differential pressure of the filter 52 reaches a predetermined threshold differential pressure, or the cumulative mileage from the end of the previous filter regeneration is predetermined. It is executed when the threshold distance is reached.

The filter 52 may be provided not only in the third embodiment but also in the exhaust aftertreatment devices of the first and second embodiments described above. If the filter 52 is provided in the first and second embodiments, soot that cannot be completely burned by the combustor 70 and flows out to the downstream side can be effectively collected. In this case, since it is difficult to perform filter regeneration control in a state where the oxygen concentration is 0 (or extremely low concentration), regeneration control such as GPF (gasoline particulate filter) may be performed.

The urea water injector 53 injects urea water stored in a urea water tank (not shown) into the downstream exhaust passage 33. The urea water injected from the urea water injector 53 is hydrolyzed by exhaust heat and water vapor in the exhaust to be produced in ammonia (NH3), and is supplied to the SCR catalyst 54 on the downstream side as a reducing agent.

The SCR catalyst 54 is formed by supporting zeolite or the like on a porous ceramic carrier, for example. The SCR catalyst 54 adsorbs ammonia supplied as a reducing agent from the urea water injector 53, and selectively reduces and purifies NOx from the exhaust passing through the adsorbed ammonia.

The ammonia slip catalyst 55 is formed by supporting an oxidation catalyst component or the like on the surface of a ceramic carrier such as a cordierite honeycomb structure, and has a function of oxidizing excess ammonia slipped downstream from the SCR catalyst 54. have.

As described above, by providing the exhaust aftertreatment device provided with the oxidation catalyst 51, the filter 52, the SCR catalyst 54, and the ammonia slip catalyst 55 in place of the three-way catalyst 50 of the first embodiment, the engine 10 is burned stoichiometrically. Even when the engine cannot be operated in the mode, it is possible to surely improve the purification performance of the exhaust gas. Further, when the catalyst temperature of the oxidation catalyst 51 or the SCR catalyst 54 is lower than the active temperature range, such as during a cold start, fuel is injected from the injector 71 to the combustor 70 to burn the catalyst temperature. It is also possible to raise the temperature to the active temperature range at an early stage.

[others]
It should be noted that the present disclosure is not limited to the above-described embodiment, and can be appropriately modified and implemented without departing from the spirit of the present disclosure.

For example, as shown in FIG. 7, the three-way catalyst 50 of the engine system 1B of the second embodiment is replaced with an exhaust aftertreatment device including an oxidation catalyst 51, a filter 52, an SCR catalyst 54, and an ammonia slip catalyst 55. May be configured. In the case of the engine system 1D shown in FIG. 7, a large amount of fuel is supplied from the injector 71 to the combustor 70 during filter regeneration for removing PM from the filter 52 and catalyst regeneration for recovering the SCR catalyst 54 from sulfur poisoning. By injecting and controlling at least the exhaust bypass valves 87 and 88 to the full open, the high temperature exhaust produced by the combustor 70 may be directly introduced into the filter 52 and the SCR catalyst 54.

Further, the application of the present disclosure is not limited to the vehicle V, and can be widely applied to the power source of industrial machines such as ships and generators.

1A, 1B, 1C, 1D engine system 10 engine (internal combustion engine)
20 Intake manifold (intake system)
21 Intake passage (intake system)
22 Upstream intake passage 23 Downstream intake passage 26 Intake throttle valve 30 Exhaust manifold (exhaust system)
31 Exhaust passage (exhaust system)
32 Upstream exhaust passage 33 Downstream exhaust passage 40 Gas turbine engine 41 Compressor passage (intake system)
42,43,44 Compressor 45 Turbine passage (exhaust system)
46, 47, 48 Turbine 49 Connecting shaft 60 EGR device 70 Combustor 71 Injector 75 Motor generator 78 In-vehicle battery 90 Boost pressure sensor (intake sensor)
92 NOx / Lambda sensor (exhaust sensor)
100 Control device (control unit)

Claims (6)

With an internal combustion engine
A turbine provided in the exhaust system of the internal combustion engine, a compressor provided in the intake system of the internal combustion engine, and a gas turbine engine having a connecting shaft connecting the turbine and the compressor.
With the motor generator provided on the connecting shaft,
A combustor provided in the exhaust system on the upstream side of the turbine, and
An injector capable of injecting fuel into the combustor,
An exhaust aftertreatment device provided in the exhaust system on the downstream side of the turbine, and
A control unit for controlling the operation of the internal combustion engine and the fuel injection of the injector is provided.
The control unit controls the operation of the internal combustion engine in a lean combustion mode, and injects fuel from the injector into the combustor to burn the fuel, thereby reducing the temperature of the exhaust gas flowing into the turbine to the internal combustion engine. An engine system characterized in that the temperature of the exhaust gas discharged from the engine is raised above the temperature and the oxygen concentration of the exhaust gas flowing into the exhaust aftertreatment device is lowered. Further, an intake throttle valve capable of adjusting the flow rate of the intake air flowing through the intake system and an exhaust gas recirculation device for recirculating the exhaust gas flowing through the exhaust system to the intake system are further provided.
The control unit has the intake throttle valve and / or the exhaust gas recirculation so that the excess air rate of the exhaust becomes equal to or less than the predetermined upper limit air excess rate when the operating state of the internal combustion engine becomes a predetermined low load operating region. The engine system according to claim 1, which controls the operation of the circulation device. The exhaust aftertreatment device is equipped with a three-way catalyst.
An exhaust sensor capable of outputting a value according to the oxygen concentration of the exhaust is provided in the exhaust system on the downstream side of the combustor and on the upstream side of the three-way catalyst.
The engine system according to claim 1 or 2, wherein the control unit controls the fuel injection amount of the injector so that the oxygen concentration of the exhaust becomes 0 based on the output value of the exhaust sensor. The engine system according to claim 1 or 2, wherein the exhaust aftertreatment device includes an oxidation catalyst, a filter, and a selective reduction catalyst in order from the exhaust upstream side. The intake system on the downstream side of the compressor is provided with an intake sensor capable of outputting the actual boost pressure according to the pressure of the intake air pressured by the compressor.
When the actual boost pressure is lower than the target boost pressure set based on the operating state of the internal combustion engine, the control unit drives the motor generator as a motor to drive the target boost pressure. The engine system according to any one of claims 1 to 4, wherein the motor generator is driven as a generator when the actual boost pressure is high. An intake bypass passage that detours the intake air flowing through the intake system from the compressor,
An intake bypass valve that can adjust the flow rate of intake air flowing through the intake bypass passage,
An exhaust bypass passage that detours the exhaust flowing through the exhaust system from the turbine,
It is further equipped with an exhaust bypass valve that can adjust the flow rate of the exhaust gas flowing through the exhaust bypass passage.
One of claims 1 to 5, wherein the control unit controls the opening degree of the intake bypass valve and the exhaust bypass valve to the open side when the operating state of the internal combustion engine becomes a predetermined low load operating region. The engine system described in.

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