JP6540595B2 - Vehicle engine system - Google Patents

Description

  The present invention relates to an engine system of a vehicle.

  Conventionally, there is an engine system of a vehicle described in Patent Document 1. The engine system described in Patent Document 1 includes a supercharger and a generator. The supercharger includes a turbine-side impeller that is rotationally driven by exhaust energy, and a compressor-side impeller that is connected to the turbine-side impeller via a rotation shaft to compress air. The generator has a rotor fixed to the rotational shaft of the turbocharger and a stator disposed around the rotor. The generator generates electricity based on the rotation of the rotating shaft of the turbocharger when limiting the output of the engine.

JP, 2005-83222, A

  By the way, in the engine system described in Patent Document 1, when the generator is driven in the limited region of the engine output, the exhaust pressure on the upstream side of the turbine side impeller in the exhaust passage, that is, the back pressure of the engine increases. Such an increase in back pressure causes an increase in the power loss of the engine.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a vehicle engine system capable of suppressing a reduction in output efficiency of the engine.

In order to solve the above problems, the engine system of the vehicle includes a main exhaust passage (71), a sub exhaust passage (72), a supercharger (3), an exhaust energy recovery device (6), and a flow rate adjustment unit (27), a load state detection unit (11, 14), and a control unit (10). In the main exhaust passage, the exhaust gas discharged from the combustion chamber (22) of the engine (2) flows, and an exhaust purification catalyst (5) is disposed. The sub exhaust passage is provided separately from the main exhaust passage, and guides the exhaust gas discharged from the combustion chamber to a portion on the upstream side of the exhaust purification catalyst in the main exhaust passage. The supercharger has a turbine wheel (31) disposed in the main exhaust passage, and a compressor wheel (30) that compresses intake air drawn into the engine based on the rotation of the turbine wheel. The exhaust energy recovery device is disposed in the sub exhaust passage. The flow rate adjustment unit adjusts the flow rate of the exhaust gas flowing through the sub exhaust passage. The load state detection unit detects a load state of the engine. The control unit controls the flow rate adjustment unit such that, when the engine is in a high load state, the flow rate of the exhaust gas flowing through the sub exhaust passage is increased as compared to the case where the engine is in a low load state. The sub exhaust passage is formed with a heat radiating portion (720a) whose passage area is enlarged.
In order to solve the above problems, the engine system of the vehicle has a main exhaust passage (71), a sub exhaust passage (72), a supercharger (3), an exhaust energy recovery device (6), and a flow rate. An adjustment unit (27), a load state detection unit (11, 14), and a control unit (10) are provided. In the main exhaust passage, the exhaust gas discharged from the combustion chamber (22) of the engine (2) flows, and an exhaust purification catalyst (5) is disposed. The sub exhaust passage is provided separately from the main exhaust passage, and guides the exhaust gas discharged from the combustion chamber to a portion on the upstream side of the exhaust purification catalyst in the main exhaust passage. The supercharger has a turbine wheel (31) disposed in the main exhaust passage, and a compressor wheel (30) that compresses intake air drawn into the engine based on the rotation of the turbine wheel. The exhaust energy recovery device is disposed in the sub exhaust passage. The flow rate adjustment unit adjusts the flow rate of the exhaust gas flowing through the sub exhaust passage. The load state detection unit detects a load state of the engine. The control unit controls the flow rate adjustment unit such that, when the engine is in a high load state, the flow rate of the exhaust gas flowing through the sub exhaust passage is increased as compared to the case where the engine is in a low load state. A throttle mechanism (7) is provided at a connection portion of the sub exhaust passage with the main exhaust passage.

  According to this configuration, when the engine is in a high load state, the passage volume of the exhaust passage is expanded as compared with the case where the engine is in a low load state. As a result, it is possible to suppress an increase in back pressure of the engine in a state in which the engine is in a high load state, so it is possible to suppress a decrease in output efficiency of the engine.

  In addition, the code | symbol in the parentheses as described in said means and a claim is an example which shows a correspondence with the specific means as described in embodiment mentioned later.

  ADVANTAGE OF THE INVENTION According to this invention, the engine system of the vehicle which can suppress the fall of the output efficiency of an engine can be provided.

FIG. 1 is a block diagram showing a schematic configuration of an engine system of the embodiment. FIG. 2 is a flowchart showing the procedure of processing executed by the engine system of the embodiment. FIG. 3 is a graph showing the relationship between the rotational speed of the engine and the output torque.

Hereinafter, an embodiment of an engine system will be described.
As shown in FIG. 1, an engine system 1 according to this embodiment includes a multi-cylinder engine 2, an exhaust turbine turbocharger 3, a throttle valve 4, an exhaust purification catalyst 5, and an exhaust energy recovery device 6. A diaphragm mechanism 7 is provided.

  The engine 2 includes a cylinder block (not shown) and a cylinder head 20 integrally assembled to the upper portion of the cylinder block. The engine 2 is provided with a plurality of combustion chambers 22, an intake manifold 23, a plurality of fuel injection valves 24, and a crankshaft 25.

  The intake manifold 23 has a plurality of branch portions 230 respectively connected to the plurality of combustion chambers 22 and a collection portion 231 in which the plurality of branch portions 230 are collected. The collecting portion 231 is connected to the intake passage 70. The intake passage 70 is a passage that guides the air outside the vehicle to the engine 2. Air supplied from the intake passage 70 to the collecting portion 231 of the intake manifold 23 is supplied to each combustion chamber 22 via the branch portion 230 of the intake manifold 23. In the intake passage 70, the compressor wheel 30 of the turbocharger 3 and the throttle valve 4 are provided in this order from the upstream side to the downstream side. The throttle valve 4 adjusts the flow rate of air passing through the intake passage 70, that is, the amount of intake air supplied to the engine 2 by adjusting the degree of opening thereof.

  The plurality of fuel injection valves 24 are respectively disposed in the plurality of combustion chambers 22. Each fuel injection valve 24 injects a fuel into the combustion chamber 22 in an amount corresponding to the amount of air supplied to the combustion chamber 22. The fuel burns in the combustion chamber 22 and the engine 2 is driven, whereby the crankshaft 25 which is an output shaft of the engine 2 is rotated.

  The cylinder head 20 is provided with an exhaust manifold 26, a flow control valve 27, and an exhaust passage 720.

  The exhaust manifold 26 has a plurality of branch portions 260 respectively connected to the plurality of combustion chambers 22 and a collection portion 261 in which the plurality of branch portions 260 are collected. The collecting portion 261 is in communication with the exhaust passage 710 outside the cylinder head 20 via the exhaust passage 262 in the cylinder head 20. Therefore, the exhaust gas discharged from each combustion chamber 22 is collected in the collecting portion 261 of the exhaust manifold 26 and then flows to the exhaust passage 710 via the exhaust passage 262. In the exhaust passage 710, the turbine wheel 31 of the turbocharger 3 and the exhaust purification catalyst 5 are disposed in order from the upstream toward the downstream. In the present embodiment, the main exhaust passage 71 is constituted by the exhaust manifold 26 and the exhaust passage 710.

  The upstream side portion of the exhaust passage 720 is in communication with the collecting portion 261 of the exhaust manifold 26. In the middle of the exhaust passage 720, a heat radiating portion 720a whose passage area is enlarged is formed. A downstream portion of the exhaust passage 720 is in communication with an exhaust passage 721 outside the cylinder head 20. The downstream side portion of the exhaust passage 721 is connected to the downstream side of the turbine wheel 31 of the turbocharger 3 in the main exhaust passage 71 and to the upstream side of the exhaust purification catalyst 5. Therefore, a part of the exhaust collected in the collecting portion 261 of the exhaust manifold 26 flows into the main exhaust passage 71 via the exhaust passage 720 and the exhaust passage 721. In the present embodiment, the exhaust passage 720 and the exhaust passage 721 constitute a sub exhaust passage 72 provided separately from the main exhaust passage 71. Further, the main exhaust passage 71 and the sub exhaust passage 72 constitute an exhaust passage 8 for leading the exhaust gas discharged from the combustion chamber 22 of the engine 2 to the exhaust purification catalyst 5.

  The flow rate adjustment valve 27 is disposed at a portion on the upstream side of the heat dissipation portion 720 a in the exhaust passage 720. The flow rate adjustment valve 27 functions as a flow rate adjustment unit that adjusts the flow rate of the exhaust gas flowing through the sub exhaust passage 72 by adjusting the opening degree thereof. When the flow rate adjustment valve 27 is fully open, the sub exhaust passage 72 is fully open, so the exhaust gas exhausted from the combustion chamber 22 of the engine 2 flows through the main exhaust passage 71 and the sub exhaust passage 72. When the flow rate adjustment valve 27 is fully closed, the sub exhaust passage 72 is fully closed, so the exhaust gas discharged from the combustion chamber 22 of the engine 2 flows only through the main exhaust passage 71.

  The supercharger 3 includes a compressor wheel 30 disposed in the intake passage 70 and a turbine wheel 31 disposed in the main exhaust passage 71. In the turbocharger 3, when the exhaust gas flowing through the main exhaust passage 71 passes the turbine wheel 31, the turbine wheel 31 rotates. The rotation of the compressor wheel 30 in conjunction with the rotation of the turbine wheel 31 supercharges the air supplied from the intake passage 70 to the combustion chamber 22. In the engine 2 in which air is supercharged by such a supercharger 3, the flow rate of the air supplied to the combustion chamber 22 and the exhaust gas discharged from the combustion chamber 22 increases as the rotational speed of the engine 2 increases, The boost pressure rises.

  The exhaust purification catalyst 5 purifies the exhaust flowing through the main exhaust passage 71. The exhaust purification catalyst 5 has a structure in which a catalytic substance is supported on a monolithic carrier which is a prismatic member made of, for example, a ceramic material.

  The exhaust energy recovery device 6 is a device that recovers the exhaust energy as electrical energy by generating power using the flow of the exhaust of the sub exhaust passage 72. The exhaust energy recovery device 6 includes a generator 60, a power converter 61, a battery 62, and a battery control unit 63.

  The generator 60 has a turbine 600 disposed in the exhaust passage 721. The turbine 600 is, for example, an axial flow turbine, and rotates based on the flow of exhaust gas in the exhaust passage 721. The generator 60 generates electric power based on the rotation of the turbine 600. The power generated by the generator 60 is converted by the power converter 61 into direct current power suitable for charging the battery 62, and then the converted direct current power is charged in the battery 62. The power charged in the battery 62 is supplied to various electronic devices mounted on the vehicle.

  The battery control unit 63 controls charging and discharging of the battery 62 while constantly monitoring a state of charge (SOC) value indicating the charging state of the battery 62. The SOC value defines the fully discharged state as 0% and the fully charged state as 100%, and then digitizes the charged state of the battery 62 in the range of 0% to 100%. The battery control unit 63 constantly monitors the power consumption of the battery 62 based on the discharge amount of the battery 62. In the present embodiment, the battery control unit 63 corresponds to a charge state detection unit that detects the charge state of the battery 62.

  The throttling mechanism 7 is provided at a connection portion of the sub exhaust passage 72 with the main exhaust passage 71. The aperture mechanism 7 is a variable aperture mechanism capable of changing the amount of aperture. The throttling mechanism 7 reduces the exhaust gas pressure by the venturi effect by partially narrowing the passage area of the sub exhaust gas passage 72. As a result, the difference between the exhaust pressure in the sub exhaust passage 72 and the exhaust pressure in the main exhaust passage 71 can be increased, so the flow rate of exhaust drawn from the sub exhaust passage 72 to the main exhaust passage 71 is increased. Do. That is, the flow rate of the exhaust flowing through the sub exhaust passage 72 is increased. Further, by changing the throttling amount of the throttling mechanism 7, it is possible to adjust the flow rate of the exhaust flowing through the sub exhaust passage 72.

  The engine system 1 includes an ECU (Electronic Control Unit) 10 that performs various controls of the engine 2. In the present embodiment, the ECU 10 corresponds to a control unit. The ECU 10 is mainly configured of a microcomputer having a CPU, a ROM, a RAM, an input port, an output port, and the like. The CPU executes arithmetic processing related to various controls of the engine 2. The ROM stores programs and data necessary for various controls of the engine 2. The calculation results of the CPU and the like are temporarily stored in the RAM. The input port and the output port are for inputting and outputting signals to and from an external device.

  An airflow meter 11, a pressure sensor 12, a throttle position sensor 13, an engine rotational speed sensor 14, a temperature sensor 15, a differential pressure sensor 16, and an accelerator position sensor 17 are connected to input ports of the ECU 10.

  The airflow meter 11 detects the amount of air passing through the intake passage 70, and outputs a detection signal corresponding to the detected amount of air to the ECU 10.

  The pressure sensor 12 detects an air pressure upstream of the throttle valve 4 in the intake passage 70 and downstream of the compressor wheel 30, and outputs a detection signal corresponding to the detected air pressure to the ECU 10.

  The throttle position sensor 13 detects a throttle opening degree, which is the opening degree of the throttle valve 4, and outputs a detection signal corresponding to the detected throttle opening degree to the ECU 10.

  The engine rotational speed sensor 14 detects an engine rotational speed, which is the rotational speed of the crankshaft 25 of the engine 2, and outputs a detection signal corresponding to the detected engine rotational speed to the ECU 10.

  The temperature sensor 15 detects the temperature of the exhaust gas flowing on the upstream side of the exhaust purification catalyst 5 in the main exhaust passage 71, and outputs a detection signal according to the detected temperature of the exhaust gas. The temperature of the exhaust purification catalyst 5 can be estimated based on the detection signal of the temperature sensor 15.

  The differential pressure sensor 16 detects a difference in exhaust pressure before and after the turbine 600 of the generator 60 in the sub exhaust passage 72, and outputs a detection signal corresponding to the detected generator differential pressure to the ECU 10.

  The accelerator position sensor 17 detects an accelerator operation amount, which is an operation amount of an accelerator pedal operated by a driver of the vehicle, and outputs a detection signal according to the detected accelerator operation amount. In the present embodiment, the accelerator position sensor 17 corresponds to a driving state detection unit that detects the driving state of the vehicle.

  The ECU 10 is communicably connected to the battery control unit 63. The ECU 10 can obtain information on the SOC value and the power consumption of the battery 62 through communication with the battery control unit 63.

  Various devices for controlling the operation of the engine 2, such as a drive circuit of the fuel injection valve 24, a drive circuit of the throttle valve 4, a drive circuit of the flow rate adjustment valve 27, and a drive circuit of the throttle mechanism 7 at the output port of the ECU 10. The drive circuit of is connected. The ECU 10 controls the fuel injection valve 24, the throttle valve 4, the flow rate adjustment valve 27, the throttle mechanism 7 and the like based on various state quantities of the engine 2 and the vehicle obtained from the detection signals of the sensors 11-17. The drive of the engine 2 is controlled.

  For example, the ECU 10 obtains the engine rotation speed Ne from the detection signal of the engine rotation speed sensor 14. Further, the ECU 10 determines the flow rate of air passing through the intake passage 70, in other words, the intake air amount Ga of the engine 2 based on the detection signal of the air flow meter 11. The ECU 10 determines the output torque Te of the engine 2 based on the determined engine rotational speed Ne and the intake air amount Ga. The ECU 10 can determine the load state of the engine 2 based on the output torque Te of the engine 2 and the engine rotation speed Ne. Thus, the ECU 10 detects the load state of the engine 2 based on the detection signals of the air flow meter 11 and the engine rotational speed sensor 14. In the present embodiment, the air flow meter 11 and the engine rotational speed sensor 14 correspond to a load state detection unit that detects the load state of the engine 2.

  Further, the ECU 10 obtains the supercharging pressure Ps from the detection signal of the pressure sensor 12. Further, the ECU 10 obtains the throttle opening degree Ta based on the detection signal of the throttle position sensor 13. The ECU 10 controls the fuel injection valve 24 and the throttle valve 4 based on the state quantities of the engine 2 such as the output torque Te, the engine rotational speed Ne, the supercharging pressure Ps, and the throttle opening degree Ta.

  Further, the ECU 10 obtains the temperature of the exhaust flowing into the exhaust purification catalyst 5 from the detection signal of the temperature sensor 15, and estimates the temperature Tc of the exhaust purification catalyst 5 based on the obtained temperature of the exhaust. Further, the ECU 10 obtains the generator back and forth differential pressure ΔPg and the accelerator operation amount Pa from the detection signals of the differential pressure sensor 16 and the accelerator position sensor 17 respectively. The ECU 10 controls the flow rate adjustment valve 27 based on the estimated temperature Tc of the exhaust purification catalyst 5, the engine rotation speed Ne, the output torque Te of the engine 2, the accelerator operation amount Pa, the SOC value of the battery 62, the generator back and forth differential pressure ΔPg, etc. Adjust the opening degree and the throttling amount of the throttling mechanism 7.

  Next, with reference to FIG. 2, the procedure of the process of adjusting the opening degree of the flow rate adjustment valve 27 and the throttling amount of the throttling mechanism 7 executed by the ECU 10 will be described. The ECU 10 repeatedly executes the process shown in FIG. 2 at a predetermined operation cycle.

  As shown in FIG. 2, the ECU 10 first determines at step S10 whether the temperature Tc of the exhaust purification catalyst 5 is less than the activation temperature Tca. If the ECU 10 makes an affirmative determination in step S10, that is, if the temperature Tc of the exhaust purification catalyst 5 is less than the activation temperature Tca, then the flow rate adjustment valve 27 is fully closed in step S16. That is, the ECU 10 controls the flow rate adjustment valve 27 so that the exhaust gas discharged from the combustion chamber 22 flows only through the main exhaust passage 71. As a result, all the high temperature exhaust collected in the collecting portion 261 of the exhaust manifold 26 flows through the main exhaust passage 71, so that the exhaust purification catalyst 5 easily rises to the activation temperature Tca.

  On the other hand, if the ECU 10 makes a negative determination in step S10, that is, if the temperature Tc of the exhaust purification catalyst 5 is equal to or higher than the activation temperature Tca, it determines whether or not the engine 2 is in a high load state as step S11. Do. Here, the high load state refers to a state where exhaust energy larger than the exhaust energy necessary to secure the activated state of the exhaust purification catalyst 5 is supplied to the exhaust purification catalyst 5, in other words, exhaust purification This means that the supply of exhaust energy to the catalyst 5 is excessive.

  Specifically, as shown in FIG. 3, the ECU 10 has at least one of the conditions that the engine rotational speed Ne is equal to or higher than a predetermined value Ne1 and that the output torque Te of the engine 2 is equal to or higher than a predetermined value Te1. If satisfied, it is determined that the engine 2 is in a high load state. The solid line shown in FIG. 3 indicates the upper limit value of the output torque Te of the engine 2 with respect to the engine rotation speed Ne. When the engine rotational speed is less than the predetermined value Ne1 and the output torque Te of the engine 2 is less than the predetermined value Te1, the ECU 10 determines that the engine 2 is in a low load state. The low load state here indicates the load state of the engine 2 excluding the high load state. The respective predetermined values Ne1 and Te1 are set in advance through experiments and the like so that it can be determined whether or not the engine 2 is in a high load state, and is stored in the ROM of the ECU 10.

  As shown in FIG. 2, when the ECU 10 makes a negative determination in step S11, that is, when the engine 2 is in a low load state, the flow rate adjustment valve 27 is fully closed in step S16. That is, the ECU 10 controls the flow rate adjustment valve 27 so that the exhaust gas discharged from the combustion chamber 22 of the engine 2 flows only through the main exhaust passage 71.

  When an affirmative determination is made in step S11, that is, when the engine 2 is in a high load state, the ECU 10 determines in step S12 whether the high load state of the engine 2 continues. Specifically, when the temporal change amount of the accelerator operation amount Pa exceeds the predetermined value, the ECU 10 determines that the high load state of the engine 2 does not continue, and the ECU 10 temporally changes the accelerator operation amount Pa. When the amount of change is equal to or less than a predetermined value, it is determined that the high load state of the engine 2 continues.

  When the negative determination is made in step S12, that is, when the high load state of the engine 2 is not continued, the ECU 10 fully closes the flow rate adjustment valve 27 as step S16.

  When an affirmative determination is made in step S12, that is, when the high load state of the engine 2 continues, the ECU 10 fully opens the flow rate adjusting valve 27 as step S13. That is, the ECU 10 controls the flow rate adjustment valve 27 so that the exhaust gas discharged from the combustion chamber 22 of the engine 2 flows through the main exhaust passage 71 and the sub exhaust passage 72. As a result, a part of the exhaust collected in the collecting portion 261 of the exhaust manifold 26 flows through the sub exhaust passage 72, so that the generator 60 generates electric power and the electric power generated by the generator 60 is charged to the battery 62.

  The ECU 10 adjusts the throttling amount of the throttling mechanism 7 as step S14 following step S13. Specifically, when the generator back-and-forth differential pressure ΔPg exceeds the predetermined value ΔPg1, the ECU 10 determines that the high power generation efficiency of the generator 60 can be secured, and the throttling amount of the throttling mechanism 7 is minimized. Set to a value. Further, when the generator back-and-forth differential pressure ΔPg is equal to or less than the predetermined value ΔPg1, the ECU 10 calculates the throttle amount capable of maximizing the power generation efficiency of the generator 60 by a map, an arithmetic expression or the like. The relationship between the generator back-and-forth differential pressure ΔPg and the throttling amount capable of maximizing the power generation efficiency of the generator 60 has been obtained in advance by experiment etc. Is stored in the ROM. The ECU 10 adjusts the aperture amount of the aperture mechanism 7 based on the calculated aperture amount.

  The ECU 10 determines whether or not charging of the battery 62 is completed, as step S15 following step S14. Specifically, the ECU 10 determines that the charging of the battery 62 is completed when the SOC value of the battery 62 is equal to or more than a predetermined value, and the battery 10 when the SOC value of the battery 62 is less than the predetermined value. It is determined that the charging of 62 has not been completed.

  If the ECU 10 makes a negative determination in step S15, it determines in step S17 whether the engine 2 is in a high load state. The determination process of step S17 is the same as the determination process of step S11.

  If the determination in step S17 is affirmative, that is, if the engine 2 is in a high load state, the ECU 10 adjusts the opening degree of the flow rate adjustment valve 27 according to the power consumption state of the battery 62 as step S18. For example, based on the past transition of the power consumption of the battery 62 obtained by the communication with the battery control unit 63, the ECU 10 may consume a predetermined amount or more of power during a period from the current time until the predetermined time has elapsed. To judge. When it is determined that the electric power more than the predetermined amount is consumed, the ECU 10 adjusts the opening degree of the flow rate adjustment valve 27 in the direction of opening as the estimated amount of electric power consumption is larger. As a result, the flow rate of the exhaust gas flowing through the sub exhaust passage 72 increases as the predicted power consumption amount increases, so the amount of power generation of the generator 60 can be increased. After executing step S18, the ECU 10 returns to step S15.

  Thereafter, when charging of the battery 62 is completed, the ECU 10 makes an affirmative determination in step S15, and makes the flow rate adjustment valve 27 fully closed as step S16. When the ECU 10 makes a negative determination in step S17 before charging of the battery 62 is completed, that is, when the engine 2 is not in the high load state, the flow rate adjusting valve 27 is fully closed in step S16. Do.

  According to the vehicle engine system 1 of the present embodiment described above, it is possible to obtain the actions and effects shown in the following (1) to (4).

  (1) When the engine 2 is in a low load state, the ECU 10 controls the flow rate adjustment valve 27 so that the exhaust gas discharged from the engine 2 flows only through the main exhaust passage 71. Further, when the engine 2 is in a high load state, the ECU 10 controls the flow rate adjustment valve 27 so that the exhaust gas discharged from the engine 2 flows through the main exhaust passage 71 and the sub exhaust passage 72. That is, when the engine 2 is in a high load state, the ECU 10 adjusts the flow rate adjustment valve 27 so that the flow rate of the exhaust gas flowing through the sub exhaust passage 72 is increased as compared with the case where the engine 2 is in a low load state. Control. Thereby, when the engine 2 is in the high load state, the passage volume of the exhaust passage 8 is expanded as compared with the case where the engine 2 is in the low load state. Therefore, since a rise in back pressure of the engine 2 can be suppressed in a state where the engine 2 is in a high load state, a reduction in output efficiency of the engine 2 can be suppressed. Further, when the engine 2 is in a high load state, the exhaust energy recovery device 6 is driven by the flow of the exhaust gas into the sub exhaust passage 72, so the exhaust energy can be efficiently used. On the other hand, when the engine 2 is in a low load state, the exhaust gas flows only in the main exhaust passage 71, so that intake air can be supercharged quickly when acceleration of the vehicle is requested. Thus, the response of the vehicle can be improved. Furthermore, by providing the supercharger 3 in the main exhaust passage 71 and providing the exhaust energy recovery device 6 in the sub exhaust passage 72, the supercharger 3 and the exhaust energy recovery device 6 can be arranged separately. Therefore, the heat generated from the turbocharger 3 becomes difficult to be transmitted to the exhaust energy recovery device 6. Therefore, damage to the exhaust energy recovery device 6 due to heat can be suppressed.

  (2) The sub exhaust passage 72 is formed with a heat radiation portion 720a whose passage area is enlarged. Thereby, since the back pressure of the engine 2 can be further suppressed, it is possible to further suppress the reduction of the output efficiency of the engine 2.

  (3) The throttling mechanism 7 is provided at a connection portion of the sub exhaust passage 72 with the main exhaust passage 71. According to such a configuration, the exhaust pressure is reduced in the throttle mechanism 7 due to the venturi effect, so the difference between the exhaust pressure in the sub exhaust passage 72 and the exhaust pressure in the main exhaust passage 71 becomes large. Therefore, the suction amount of the exhaust gas from the sub exhaust passage 72 to the main exhaust passage 71 is increased. As a result, the flow rate of the exhaust flowing through the sub exhaust passage 72 is increased, so that the exhaust energy recovery efficiency in the exhaust energy recovery device 6 can be enhanced.

  (4) The aperture mechanism 7 comprises a variable aperture mechanism capable of changing the amount of aperture. The ECU 10 changes the throttling amount of the throttling mechanism 7 based on the parameter indicating the driving state of the exhaust energy recovery device 6, specifically, the generator front-rear differential pressure ΔPg. Thereby, the recovery efficiency of the exhaust energy in the exhaust energy recovery device 6 can be further enhanced.

In addition, the said embodiment can also be implemented with the following forms.
The throttle mechanism 7 may be a fixed throttle valve whose throttle amount is fixed to a predetermined value.
The exhaust energy recovery device 6 disposed in the sub exhaust passage 72 is not limited to the generator 60, and any device driven using exhaust energy may be used.

  The ECU 10 may fully open the flow control valve 27 when the engine 2 is in the high load state regardless of whether the high load state of the engine 2 continues. Even with such a configuration, a rise in back pressure of the engine 2 can be suppressed in a state in which the engine 2 is in a high load state, so a decrease in output efficiency of the engine 2 can be suppressed.

  In the cylinder head 20 of the above-described embodiment, the exhaust manifold 26 and the heat radiating portion 720a are connected via a part of the exhaust passage 720. However, these may be spatially separated. In this case, the cylinder head 20 is provided with an exhaust passage for guiding the exhaust gas discharged from each combustion chamber 22 to the heat radiating portion 720a. Further, instead of the flow rate adjustment valve 27, the cylinder head 20 is provided with an on-off valve capable of flowing the exhaust gas discharged from each combustion chamber 22 to any one of the exhaust manifold 26 and the heat radiating portion 720a. Then, the ECU 10 controls the on-off valve so that the exhaust gas discharged from each combustion chamber 22 flows only to the exhaust manifold 26, as step S16 shown in FIG. Further, at step S13 shown in FIG. 2, the ECU 10 controls the on-off valve so that the exhaust gas discharged from each combustion chamber 22 flows only to the heat radiation portion 720a. Furthermore, ECU10 adjusts the opening degree of an on-off valve as step S17.

  The positional relationship between the collecting portion 261 of the exhaust manifold 26 of the cylinder head 20 and the heat radiating portion 720a can be changed as appropriate. For example, when the direction in which the piston reciprocates in the combustion chamber 22 is the vertical direction, the heat radiating portion 720a may be disposed at a position vertically offset with respect to the collecting portion 261 of the exhaust manifold 26.

  The ECU 10 may determine whether the engine 2 is in the high load state based on an arbitrary state quantity of the engine 2 in steps S11 and S17 shown in FIG. The state quantities of the engine 2 used at this time include the temperature of the exhaust flowing into the turbine wheel 31, the temperature of the exhaust flowing out of the turbine wheel 31, the pressure of the exhaust flowing into the turbine wheel 31, and the exhaust before and after the turbine wheel 31. The pressure difference, the rotational speed of the supercharger 3, the in-cylinder pressure which is the pressure in each combustion chamber 22, the pressure in the intake manifold 23, etc. can be used. Needless to say, when using these state quantities of the engine 2, an appropriate sensor capable of detecting it is necessary.

  The engine system 1 may have a temperature sensor that directly detects the temperature of the exhaust purification catalyst 5 instead of the temperature sensor 15.

  The ECU 10 may determine whether or not the high load state of the engine 2 continues, based on an arbitrary state quantity of the vehicle, as Step S12 shown in FIG. For example, the ECU 10 detects the speed of the vehicle by the vehicle speed sensor, and determines that the high load state of the engine 2 does not continue if the temporal change amount of the speed of the vehicle exceeds a predetermined value. When the temporal change amount of the speed of the vehicle is equal to or less than a predetermined value, it may be determined that the high load state of the engine 2 continues.

  In step S16 shown in FIG. 2, the ECU 10 may set the opening degree of the flow rate adjustment valve 27 to an opening degree that is a predetermined opening degree from the fully closed state. Further, in step S13 shown in FIG. 2, the ECU 10 may set the opening degree of the flow rate adjustment valve 27 to an opening degree closed by a predetermined opening degree from the fully open state.

  In the process of step S14 shown in FIG. 2, the ECU 10 is not limited to the generator front-rear differential pressure ΔPg, and for example, the throttle amount of the throttle mechanism 7 based on the generator rotational speed which is the rotational speed of the turbine 600 of the generator 60. You may adjust the In this case, when the generator rotational speed exceeds the predetermined value, the ECU 10 determines that the high power generation efficiency of the generator 60 can be secured, and sets the throttling amount of the throttling mechanism 7 to the minimum value. Further, when the generator rotational speed is equal to or less than a predetermined value, the ECU 10 calculates the throttle amount capable of maximizing the power generation efficiency of the generator 60 by using a map, an arithmetic expression, or the like.

  The means and / or functions provided by the ECU 10 can be provided by software stored in the tangible ROM and a computer that executes the same, only software, only hardware, or a combination thereof. For example, if the ECU 10 is provided by an electronic circuit that is hardware, it can be provided by a digital circuit or analog circuit that includes a number of logic circuits.

  The present invention is not limited to the above specific example. That is, to the above specific examples, those skilled in the art may appropriately modify the design as long as the features of the present invention are included in the scope of the present invention. For example, each element included in each specific example described above and its arrangement, conditions, and the like are not limited to those illustrated, and can be appropriately changed. Moreover, each element with which the above-mentioned embodiment is equipped can be combined as much as technically possible, and what combined these is also included in the scope of the present invention as long as the feature of the present invention is included.

1: Engine system 2: Engine 3: Turbocharger 5: Exhaust purification catalyst 6: Exhaust energy recovery device 7: Throttling mechanism 10: ECU (control unit)
11: Air flow meter (load condition detector)
14: Engine speed sensor (load condition detector)
17: Accelerator position sensor (operating condition detection unit)
22: combustion chamber 27: flow control valve (flow control unit)
30: compressor wheel 31: turbine wheel 60: generator 62: battery 63: charge state detection unit 71: main exhaust passage 72: sub exhaust passage 270a: heat dissipation unit

Claims (7)

Main exhaust passage (71) in which the exhaust gas discharged from the combustion chamber (22) of the engine (2) flows and the exhaust purification catalyst (5) is disposed;
A sub exhaust passage (72) which is provided separately from the main exhaust passage and guides the exhaust gas discharged from the combustion chamber to a portion of the main exhaust passage upstream of the exhaust purification catalyst;
A turbocharger (3) having a turbine wheel (31) disposed in the main exhaust passage, and a compressor wheel (30) for supercharging intake air taken into the engine based on rotation of the turbine wheel.
An exhaust energy recovery device (6) disposed in the sub exhaust passage;
A flow rate adjusting unit (27) for adjusting the flow rate of the exhaust gas flowing through the sub exhaust passage;
A load condition detection unit (11, 14) for detecting a load condition of the engine;
A control unit (10) for controlling the flow rate adjusting unit;
The control unit
When the engine is in a high load state, the flow rate control unit is controlled so that the flow rate of the exhaust gas flowing through the sub exhaust passage is increased as compared to the case where the engine is in a low load state ;
In the sub exhaust passage,
An engine system of a vehicle in which a radiator (720a) whose passage area is enlarged is formed . The engine system of a vehicle according to claim 1, wherein a throttle mechanism (7) is provided at a connection portion of the sub exhaust passage with the main exhaust passage.   Main exhaust passage (71) in which the exhaust gas discharged from the combustion chamber (22) of the engine (2) flows and the exhaust purification catalyst (5) is disposed;
  A sub exhaust passage (72) which is provided separately from the main exhaust passage and guides the exhaust gas discharged from the combustion chamber to a portion of the main exhaust passage upstream of the exhaust purification catalyst;
  A turbocharger (3) having a turbine wheel (31) disposed in the main exhaust passage, and a compressor wheel (30) for supercharging intake air taken into the engine based on rotation of the turbine wheel.
  An exhaust energy recovery device (6) disposed in the sub exhaust passage;
  A flow rate adjusting unit (27) for adjusting the flow rate of the exhaust gas flowing through the sub exhaust passage;
  A load condition detection unit (11, 14) for detecting a load condition of the engine;
  A control unit (10) for controlling the flow rate adjusting unit;
  The control unit
  When the engine is in a high load state, the flow rate control unit is controlled so that the flow rate of the exhaust gas flowing through the sub exhaust passage is increased as compared to the case where the engine is in a low load state;
  A throttle mechanism (7) is provided at a connection portion of the sub exhaust passage with the main exhaust passage.
  Vehicle engine system. The aperture mechanism is a variable aperture mechanism capable of changing the amount of aperture thereof,
The control unit
The engine system of a vehicle according to claim 2 or 3 , wherein the throttling amount of the throttling mechanism is changed based on a parameter indicating a driving state of the exhaust energy recovery device. The exhaust energy recovery device
A generator (60) for generating electricity based on the flow of exhaust gas in the sub exhaust passage;
A battery (62) for charging the electric power generated by the generator;
A charge state detection unit (63) for detecting the charge state of the battery;
The control unit
The engine system of a vehicle according to claim 4 , wherein the throttle amount of the throttle mechanism is changed based on a charge state of the battery.   The control unit
  When the engine is in a low load state, the flow rate control unit is controlled such that exhaust gas discharged from the engine flows only through the main exhaust passage;
  When the engine is in a high load state, the flow rate control unit is controlled such that the exhaust gas discharged from the engine flows through the main exhaust passage and the sub exhaust passage.
  The engine system of the vehicle according to any one of claims 1 to 5.   The vehicle further includes a driving state detection unit (16) that detects the driving state of the vehicle,
  The control unit
  It is determined based on the driving state of the vehicle whether or not the high load state of the engine is to be continued,
  When it is determined that the high load state of the engine is continued, the flow rate adjusting unit is configured to increase the flow rate of the exhaust flowing through the sub exhaust passage, as compared to the case where the engine is in the low load state. Control
  The engine system of the vehicle according to any one of claims 1 to 6.

Images