JP6184741B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine.

  2. Description of the Related Art In recent years, an internal combustion engine including an electrically assisted turbocharger that assists the drive of a turbocharger with an electric motor in order to realize low fuel consumption of the vehicle is known (for example, see Patent Document 1). In this internal combustion engine, appropriate intake efficiency is ensured by rotating the turbine with an electric motor when the exhaust pressure does not rise in time, such as when the vehicle is suddenly accelerated.

JP 2010-265810 A

  By the way, in an internal combustion engine including a fixed-wing turbocharger in which the opening area of the turbine blade is constant, the exhaust pressure may be lower than the intake pressure depending on the traveling state of the vehicle. In this case, since EGR cannot be applied, the exhaust throttle valve is controlled to increase the exhaust pressure above the intake pressure. However, there is a problem in that sufficient energy recovery is not performed for the increased exhaust pressure, and fuel consumption is deteriorated due to exhaust pressure loss.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an internal combustion engine capable of appropriately recovering energy from exhaust gas while realizing adjustment of exhaust pressure.

The present invention includes a turbine provided in an exhaust passage of an internal combustion engine that is a diesel engine, and includes energy recovery means for recovering energy from exhaust gas, and control means for controlling the energy recovery means. Is a turbo generator that generates power by rotating the turbine, and the control means adjusts the exhaust pressure in the exhaust passage by changing the rotational load of the turbine, and when applying the exhaust brake, An exhaust brake is applied by increasing the exhaust pressure in the passage .

  According to the internal combustion engine of the present invention, the energy recovery means for recovering energy from the exhaust gas is provided, and the exhaust gas is made difficult to exhaust or easy to exhaust by changing the rotational load of the turbine of the energy recovery means. The exhaust pressure in the passage can be adjusted. Moreover, according to this internal combustion engine, the increased exhaust pressure always passes through the turbine, so that the energy can be recovered. Therefore, according to this internal combustion engine, it is possible to appropriately recover energy from the exhaust gas while realizing adjustment of the exhaust pressure. Thereby, the fuel consumption improvement of an internal combustion engine can be aimed at.

The internal combustion engine according to the present invention further includes a fixed-wing turbocharger that supercharges the air in the intake passage, and an EGR that introduces a portion of the exhaust gas in the exhaust passage into the intake passage. May change the rotational load of the turbine so that the exhaust pressure in the exhaust passage becomes higher than the intake pressure in the intake passage.
According to this internal combustion engine, by changing the rotational load of the turbine so that the exhaust pressure becomes higher than the intake pressure, EGR can be applied even when the exhaust pressure decreases due to the operating state of the internal combustion engine. Further, according to the internal combustion engine, the energy of the exhaust pressure increased for effecting EGR can be recovered by the turbine, so that deterioration in fuel consumption due to exhaust pressure loss can be suppressed.

  According to the internal combustion engine of the present invention, it is possible to appropriately recover energy from exhaust gas while realizing adjustment of exhaust pressure.

It is the schematic which shows the diesel engine which concerns on 1st Embodiment. It is the schematic which shows the diesel engine which concerns on 2nd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an internal combustion engine according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
A diesel engine 1 according to the first embodiment shown in FIG. 1 is an on-board internal combustion engine provided in a vehicle such as a truck, a bus or the like. The diesel engine 1 is comprehensively controlled by an ECU [Engine Control Unit] 2. The ECU 2 is an electronic control unit (control means) including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like.

  The diesel engine 1 includes an engine body 3 having a plurality of cylinders, an intake passage 4 for supplying air to the engine body 3, an exhaust passage 5 for exhausting exhaust gas from the engine body 3, and an intake passage. 4 and a turbocharger 6 for supercharging.

  The intake passage 4 is provided with an air cleaner 7 for trapping dust in the air to obtain clean air, and an intercooler 8 for cooling the air whose temperature has risen due to supercharging. In the intake passage 4, a compressor 6 a of a turbocharger 6 is provided between the air cleaner 7 and the intercooler 8.

  On the other hand, the turbine 6 b of the turbocharger 6 is provided in the exhaust passage 5. In the turbocharger 6, the turbine 6 b is rotated by the pressure of the exhaust gas discharged from the engine body 3, whereby the compressor 6 a is driven to rotate and the air in the intake passage 4 is supercharged. The turbocharger 6 is a fixed-wing supercharger, and the opening area of the turbine blade of the turbine 6b is constant.

  The exhaust passage 5 includes a turbo generator 9 that recovers the energy of the exhaust gas and a post-processing system 10 that processes the exhaust gas. The aftertreatment system 10 is an exhaust gas treatment system including an oxidation catalyst for purifying exhaust gas, a NOx reduction device, and the like.

  The turbo generator 9 is energy recovery means for recovering the energy of the exhaust gas as electric power. The turbo generator 9 includes a turbine 9a provided in the exhaust passage 5, and a motor 9b connected to the turbine 9a via a shaft.

  In the turbo generator 9, the turbine 9a is rotated by the pressure (exhaust pressure) of the exhaust gas discharged from the engine body 3, and power is generated in the motor 9b. The electric power generated by the motor 9b is stored in an in-vehicle battery. The battery preferably has a large capacity such as a lithium ion battery.

  The turbo generator 9 is controlled by the ECU 2. The ECU 2 changes the rotational load (rotational torque) of the turbine 9a. A method of changing the rotational load of the turbine 9a is not particularly limited, and examples thereof include a method of suppressing the rotation of the shaft using an electromagnet. The electromagnet may be provided in the motor 9b or may be provided separately from the motor 9b. Moreover, you may provide the generator for rotation suppression separately. In addition, the structure which changes the rotational load of the turbine 9a mechanically using friction etc. may be sufficient.

  The diesel engine 1 includes an EGR [Exhaust Gas Recirculation] passage 11. The EGR passage 11 is a passage for performing exhaust gas recirculation for the purpose of suppressing NOx and improving fuel consumption, and connects the exhaust passage 5 and the intake passage 4. The EGR passage 11 is provided with an EGR cooler 12 that cools part of the exhaust gas (EGR gas) introduced from the exhaust passage 5 and an EGR valve 13 that controls the flow rate of the EGR gas.

  In the diesel engine 1, the exhaust pressure of the exhaust passage 5 is adjusted by changing the rotational load of the turbine 9 a by the ECU 2. Specifically, the ECU 2 adjusts the exhaust pressure for controlling the EGR rate. Even when the exhaust pressure is lower than the intake pressure depending on the operating condition of the engine (for example, when a high torque load is applied to the engine), the ECU 2 makes the exhaust pressure higher than the intake pressure in order to properly apply EGR. The exhaust pressure is adjusted by changing the rotational load of the turbine 9a so as to increase.

  Further, the ECU 2 increases the rotational load of the turbine 9a when the exhaust brake is applied, such as when the driver operates the exhaust brake button. The ECU 2 increases the rotational load of the turbine 9a to increase the exhaust pressure, thereby increasing the pumping loss of the engine and exerting the braking force. Note that the ECU 2 may fix the turbine 9a when the exhaust brake is applied so that the turbine 9a cannot rotate. Moreover, the diesel engine 1 may be separately provided with an exhaust throttle valve dedicated to the exhaust brake.

  According to the diesel engine 1 which concerns on 1st Embodiment demonstrated above, the turbo generator 9 which collect | recovers energy from exhaust gas is provided, and exhaust gas is discharged | emitted by changing the rotational load of the turbine 9a of the turbo generator 9 The exhaust pressure can be adjusted by making it difficult or easy to discharge. Moreover, in the diesel engine 1, the increased exhaust pressure always passes through the turbine 9a, so that the energy can be recovered. Therefore, according to the diesel engine 1, energy can be appropriately recovered from the exhaust gas while adjusting the exhaust pressure. Thereby, the fuel consumption improvement of a diesel engine can be aimed at.

  Further, in this diesel engine 1, in order to control the EGR rate, the exhaust pressure can be adjusted by changing the rotational load of the turbine 9a so that the exhaust pressure becomes higher than the intake pressure. According to the diesel engine 1, since the energy of the exhaust pressure increased for effecting EGR can be recovered by the turbine 9a, fuel consumption deterioration due to exhaust pressure loss can be suppressed. As a result, there is no need to use the exhaust throttle valve in the normal exhaust adjustment, and the exhaust throttle valve can be dedicated to the exhaust brake. In this case, since the frequency of use of the exhaust throttle valve is significantly reduced, it is possible to extend the life of the exhaust throttle valve and simplify the configuration. It is not always necessary to provide an exhaust throttle valve.

  Furthermore, according to the diesel engine 1, by increasing the rotational load of the turbine 9a, the exhaust pressure can be increased to increase the pumping loss and the exhaust brake can be applied. Moreover, according to the diesel engine 1, the energy of the exhaust pressure increased in the exhaust brake can be recovered as the rotation of the turbine 9a, which is advantageous in improving fuel consumption. In the diesel engine 1, the exhaust gas energy can be recovered as highly versatile power by the turbo generator 9. The recovered power can be stored in the battery and can be used for various purposes.

[Second Embodiment]
The diesel engine 20 according to the second embodiment shown in FIG. 2 is greatly different from the diesel engine 1 according to the first embodiment in that an electric assist turbo 21 is provided instead of the turbo generator 9. . In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and the overlapping description is abbreviate | omitted.

  The electric assist turbo 21 is energy recovery means that recovers the energy of exhaust gas as rotational energy, and transmits the rotational energy to the crankshaft 3 a of the diesel engine 20. The electric assist turbo 21 has a turbine 21a provided in the exhaust passage 5 and a gear 21b connected to the turbine 21a via a shaft.

  The gear 21 b meshes with the gear 22 on the input side of the fluid coupling 23. The fluid coupling 23 is a coupling that transmits rotational motion via a fluid. The output side gear 24 of the fluid coupling 23 is interlocked with the gear 27 of the flywheel 26 via the intermediate gear 25. The flywheel 26 is connected to the crankshaft 3a. With such a configuration, the rotational output of the gear 21b of the electric assist turbo 21 is transmitted to the crankshaft 3a.

  The electric assist turbo 21 is also controlled by the ECU 2, and the ECU 2 adjusts the exhaust pressure by changing the rotational load of the turbine 21a.

  According to the diesel engine 20 which concerns on 2nd Embodiment demonstrated above, the effect similar to 1st Embodiment can be acquired. The diesel engine 20 includes an electric assist turbo 21 instead of the turbo generator 9 according to the first embodiment, and can transmit the energy of the exhaust gas to the crankshaft 3a as rotational energy. In this case, the exhaust gas energy can be recovered with high efficiency, which is advantageous in improving fuel consumption.

  The present invention is not limited to the embodiment described above. For example, the present invention is not limited to a diesel engine but can be applied to a gasoline engine. Moreover, it is not necessarily a fixed-wing turbocharger, and a variable capacity turbocharger having a variable nozzle vane may be provided. Moreover, you may utilize a turbocharger as an energy recovery means as described in a claim. The turbocharger in this case can be the second stage of the two-stage turbo.

  DESCRIPTION OF SYMBOLS 1,20 ... Diesel engine (internal combustion engine) 2 ... ECU (control means) 3 ... Engine main body 3a ... Crankshaft 4 ... Intake passage 5 ... Exhaust passage 6 ... Turbocharger 6a ... Compressor 6b ... Turbine 7 ... Air cleaner 8 ... Intercooler DESCRIPTION OF SYMBOLS 9 ... Turbo generator (energy recovery means) 9a ... Turbine 9b ... Motor 10 ... Post-processing system 11 ... EGR passage 12 ... EGR cooler 13 ... EGR valve 21 ... Electric assist turbo (energy recovery means) 21a ... Turbine 21b ... Gear 22 , 24, 27 ... gear 23 ... fluid coupling 25 ... intermediate gear 26 ... flywheel

Claims (2)

An energy recovery means for recovering energy from exhaust gas having a turbine provided in an exhaust passage of an internal combustion engine which is a diesel engine ;
Control means for controlling the energy recovery means;
With
The energy recovery means is a turbo generator that generates electricity by rotation of the turbine,
The control means adjusts the exhaust pressure in the exhaust passage by changing the rotational load of the turbine, and when applying the exhaust brake, the control means increases the exhaust pressure in the exhaust passage by fixing the turbine. An internal combustion engine characterized by applying a brake . A fixed-wing turbocharger that supercharges air in the intake passage of the internal combustion engine;
EGR for introducing a part of the exhaust gas of the exhaust passage into the intake passage,
The internal combustion engine according to claim 1, wherein the control means changes the rotational load of the turbine so that an exhaust pressure in the exhaust passage becomes higher than an intake pressure in the intake passage.

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