JP2017214889A - Engine with turbosupercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of fuel consumption performance while securing a supercharging pressure and a power generation amount by making effective use of the energy of exhaust gas.SOLUTION: In an engine with a turbosupercharger, there are provided a turbosupercharger, a turbine side power generator, and a bypass passage bypassing a supercharging turbine and an opening/closing valve for opening/closing it. The supercharging turbine develops the maximum turbine efficiency at a speed lower than reference one in a high-load region and the maximum compressor efficiency at the speed not lower than the reference one. When the speed is not lower than the reference one in the high-load region, the opening/closing valve is opened so that power generation is preferentially carried out in a specified region where the maximum compressor efficiency is developed, out of the high-speed and high-load region.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a turbocharged engine.

  Conventionally, in an engine system, a turbocharger has been provided in order to increase engine torque, and it has been studied to increase energy efficiency in the entire engine system.

  For example, Patent Document 1 discloses a turbocharger including a turbocharger and a generator that generates power by the rotational force of a shaft that connects a turbine and a compressor provided in the turbocharger. In the engine system disclosed in Patent Document 1, the turbine of the turbocharger is a so-called variable capacity turbine, and includes a turbine having a variable vane that can change the flow area of the exhaust gas flowing into the turbine main body. When the rotation speed exceeds a predetermined number of revolutions, the opening of the variable vane and thus the flow passage area is increased, and power generation is started. Further, in this engine system, the opening of the variable vane is corrected to the throttle side at the time of power generation in order to suppress a decrease in the supercharging pressure accompanying power generation, and the pressure on the upstream side of the turbine and the back of the engine accompanying this correction are corrected. The turbine efficiency is maximized in a region where the engine speed at which power generation is performed to suppress an increase in pressure is greater than or equal to a predetermined speed.

JP 2007-262970 A

  In the engine system of Patent Document 1, as described above, power generation is performed while the turbine efficiency is maximized in a region where the engine speed is equal to or higher than a predetermined speed. In this region, the supercharging pressure and the power generation amount are reduced. While ensuring high, the deterioration of the pumping loss accompanying the increase of the back pressure of the engine, that is, the deterioration of the fuel efficiency can be suppressed. However, in this configuration, since the turbine efficiency is low in the low speed region where the engine speed is less than the predetermined speed, the pressure on the upstream side of the turbine, that is, the engine back pressure is high when attempting to achieve a high boost pressure in this low speed region. Thus, there is a problem that the pumping loss and the fuel consumption performance are deteriorated.

  The present invention has been made in view of the circumstances as described above, and is a turbocharger that can further suppress deterioration in fuel consumption performance while ensuring supercharging pressure and power generation amount by effectively using exhaust energy. An object is to provide a supercharged engine.

  In order to solve the above-described problems, the present invention provides a turbocharged engine, an engine body, an intake passage and an exhaust passage connected to the engine body, a compressor provided in the intake passage, and the A turbocharger including a supercharging turbine provided in an exhaust passage; a power generation turbine provided downstream of the supercharging turbine in the exhaust passage and rotating in response to exhaust energy; and the power generation A power generator including a turbine-side power generator driven by a turbine, and a control unit capable of controlling each part of the engine including the turbine-side power generator, wherein the exhaust passage bypasses the supercharging turbine A bypass passage for introducing exhaust gas into the power generation turbine, and an on-off valve for opening and closing the bypass passage. In the high load region where the engine load is equal to or higher than the reference load, the impeller that rotates by receiving the energy of the motor and the housing that houses the impeller and has a constant flow passage area of the exhaust flowing into the impeller. The turbine efficiency of the supercharging turbine is set such that the engine speed is maximized at a speed lower than a preset reference speed, and the compressor efficiency of the compressor is such that the engine speed is equal to the reference speed. The control means sets the on-off valve to be fully closed when the engine speed is less than the reference speed in the high load region, while the high load is set to be maximum. In the high-speed and high-load region where the engine speed is equal to or higher than the reference rotational speed in the region, the on-off valve is opened, and When the engine is operated in a specific region including at least the engine speed at which the compressor efficiency is maximized and there is a power generation request for the generator, the generator is caused to generate power and the operation is performed outside the specific region. An engine with a turbocharger is provided, wherein an engine is operated in a region, and when there is a demand for power generation, power generation by the power generator is performed or stopped according to conditions (claim) Item 1).

  In this configuration, the on-off valve is opened in the high-speed and high-load region, and part of the exhaust energy is introduced into the power generation turbine without being used in the supercharging turbine. In the specific region set in at least a part of the high-speed and high-load region, power generation is always performed when there is a power generation request. For example, power generation is stopped depending on the urgency of power generation. Thus, with this configuration, power generation is preferentially performed in a specific region where the engine speed and engine load are high and the exhaust energy is high. Therefore, the boost pressure can be increased while efficiently using the energy of the exhaust for power generation.

  In particular, this configuration is configured such that the compressor efficiency is maximized in the specific region, and the turbine efficiency is maximized in a low speed and high load region where the engine speed is lower than that in the specific region. Therefore, it is possible to suppress the increase in pumping loss by sufficiently increasing the supercharging pressure while securing a high power generation amount in a specific region, and also to ensure a high supercharging pressure even in a low speed and high load region. Can be prevented from excessively increasing. Therefore, the pumping loss can be suppressed while increasing the supercharging pressure over a wider range, and the fuel efficiency can be improved.

  Further, in this configuration, a so-called fixed capacity turbine is used as the supercharging turbine, which is a turbine configured to maintain a constant flow passage area of the exhaust gas flowing into the impeller. Therefore, it is more advantageous in terms of cost than when a variable capacity turbine is used as the supercharging turbine. And, since the turbine efficiency of the supercharging turbine, which is this fixed capacity turbine, is set high in the low-speed and high-load region, it is effective even in the low-speed and high-load region where the engine speed is low and the exhaust flow rate is small. The supercharging pressure can be increased.

  In the above configuration, the efficiency of the compressor is set so as to increase as the engine speed increases and exceed the efficiency of the supercharging turbine at a predetermined engine speed. It is preferable that the compressor efficiency is set in an area where the compressor efficiency is equal to or higher than the efficiency at the predetermined engine speed in the high load area.

  In this way, the turbocharger efficiency (turbine efficiency and compressor efficiency) can be increased equally in both the low speed and high load areas, and the engine speed can be more evenly fueled. Performance can be increased.

  In the above-described configuration, an engine-side generator is connected to the output shaft of the engine main body and is driven to rotate by the output shaft, and the control means is configured to operate the engine in a region on a lower load side than the specific region. When the engine is in operation and there is a power generation request for the generator, it is preferable to drive the engine-side generator so that the engine load becomes a load within the specific region.

  In this way, since it is possible to increase the power generation opportunities in the specific area, it is possible to reduce the frequency of power generation outside the specific area, and it is possible to suppress deterioration in fuel consumption performance. Moreover, since power generation is also performed by the engine-side generator, the power generation amount can be further increased.

  As described above, according to the turbocharged engine of the present invention, it is possible to suppress deterioration of fuel consumption performance while ensuring the supercharging pressure and the power generation amount.

It is a schematic block diagram of an engine system. It is a schematic sectional drawing of an engine main body. It is the figure which showed the relationship between the engine speed in a high load area | region and the opening degree of a waste gate valve. It is the figure which showed the driving | operation area | region. It is the figure which showed the relationship between the engine speed in a high load area | region, turbine efficiency, and compressor efficiency. It is the figure which showed the control block. It is the flowchart which showed the procedure of the control which concerns on a waste gate valve, VGT opening degree, and a generator.

(1) Overall Configuration FIG. 1 is a schematic configuration diagram of a turbocharged engine 100 (hereinafter, appropriately referred to as an engine system 100) according to an embodiment of the present invention.

  The engine system 100 includes an engine body 1, an intake passage 120 through which intake air introduced into the engine body 1 circulates, an exhaust passage 130 through which exhaust gas (combustion gas) derived from the engine body 1 circulates, and an exhaust passage 130. The turbocharger 60 is driven by the exhaust gas flowing, and the power generator 70 is driven by the exhaust gas flowing through the exhaust passage 130 to generate electric power. Here, as shown in FIG. 1 and the like, a case will be described in which the engine body 1 is a four-stroke in-line four-cylinder gasoline engine and is mounted on a vehicle as a drive source.

  FIG. 2 is a schematic sectional view of the engine body 1.

  The engine body 1 includes a cylinder block 101 in which a cylinder 10 is formed, a cylinder head 102 provided on the upper surface of the cylinder block 101, and a piston 103 that is inserted into the cylinder 10 so as to be slidable back and forth. Yes.

  The piston 103 is connected to a crankshaft (an output shaft of the engine main body 1) 106 via a connecting rod, and the crankshaft 106 rotates around its central axis in accordance with the reciprocating motion of the piston 103.

  As shown in FIG. 1, an engine-side generator 82 that is driven by the rotational force of the crankshaft 106 to generate electric power is connected to the crankshaft 106. In the present embodiment, the engine-side generator 82 is a generator with a motor function, so-called ISG (Integrated Starter Generator), which is driven by the crankshaft 106 as described above to function as a generator, and at the time of starting or acceleration. It functions as a motor at times and assists the rotation of the crankshaft 106. The engine-side generator 82 is controlled by the ISG drive device 85, and the ISG drive device 85 switches between the generator and the motor, and the amount of power generation and the driving force as the motor are changed.

  A combustion chamber 5 is formed above the piston 103. An injector 105 is attached to the side wall of the cylinder block 101 so as to face the combustion chamber 5. Fuel is injected from the injector 105 into the combustion chamber 5. The injected fuel / air mixture burns in the combustion chamber 5, and the piston 103 is pushed down by the expansion force generated by the combustion, and reciprocates up and down. The injector 105 may be attached to the cylinder head 102.

  The cylinder head 102 is provided with a spark plug 18 that performs ignition by spark discharge on the mixture of fuel and air injected from the injector 105.

  In the cylinder head 102, corresponding to each cylinder 10, an intake port 13 for introducing air supplied from the intake passage 120 into the combustion chamber 5 of each cylinder 10 and an intake valve 14 for opening and closing the intake port 13. And an exhaust port 11 for leading exhaust generated in the combustion chamber 5 of each cylinder 10 to the outside of the engine body 1 and an exhaust valve 12 for opening and closing the exhaust port 11.

  The intake passage 120 is provided so as to be connected to each intake port 13. In the intake passage 120, a compressor 62, an intercooler 122, a throttle valve 123, and a surge tank 124 are provided in this order from the upstream side.

  The compressor 62 is a component part of the turbocharger 60. That is, the turbocharger 60 includes a turbocharger 64 that is provided in the exhaust passage 130 and is rotationally driven by exhaust gas, and a compressor 62 that is provided in the intake passage 120 and is rotationally driven by the turbocharger turbine 64. The supercharging turbine 64 (specifically, an impeller 64a to be described later of the supercharging turbine 64) rotates upon receiving the introduction of exhaust gas, whereby the compressor 62 rotates to supercharge intake air.

(2) Exhaust System The exhaust passage 130 is provided so as to be connected to each exhaust port 11 of the engine body 1. In the exhaust passage 130, a supercharging turbine 64, a power generation turbine 74, and a catalyst device 90 are provided in this order from the upstream side.

  In this embodiment, the supercharging turbine 64 is a fixed capacity turbine, so-called FGT (Fixed Geometry Turbine), and the supercharging turbine 64 includes an impeller 64a that rotates by receiving the energy of exhaust gas, and a housing that accommodates the impeller 64a. 64h, and the flow passage area of the exhaust gas flowing into the impeller 64a is fixed to a constant value. That is, the supercharging turbine 64 is not a variable capacity turbine (VGT) having a variable vane that can change the flow passage area of the exhaust gas flowing into the impeller, and does not have a variable vane.

  The power generation turbine 74 is a component of the power generation apparatus 70. The power generation device 70 includes the power generation turbine 74, a generator (turbine side generator) 72 that is rotationally driven by the power generation turbine 74, and a generator drive device 75 that drives the generator 72.

  The power generation turbine 74 is a turbine that rotates by receiving the energy of the exhaust, and the generator 72 generates power by being rotationally driven by the power generation turbine 74. Specifically, the generator 72 has a rotor coil that rotates in conjunction with the power generation turbine 74, and generates power by electromagnetic induction accompanying the rotation of the rotor coil. The electric power generated by the generator 72 is stored in a battery (not shown) or supplied to various electric devices (not shown).

  The generator driving device 75 switches execution / stop of power generation by the generator 72, that is, execution / stop of application of magnetization current to the rotor coil of the generator 72, and changes the power generation amount of the generator 72.

  The catalyst device 90 is a device for purifying exhaust gas, and includes, for example, an oxidation catalyst.

  The exhaust passage 130 is provided with a bypass passage 132 that bypasses the power generation turbine 74 and a wastegate valve (open / close valve) 133 that opens and closes the bypass passage 132. Specifically, the bypass passage 132 connects a portion of the exhaust passage 130 upstream of the supercharging turbine 64 and a portion between the supercharging turbine 64 and the power generation turbine 74. Accordingly, in a state where the wastegate valve 133 is open, a part of the exhaust discharged from the engine body 1 flows into the power generation turbine 74 without passing through the supercharging turbine 64.

  The supercharging pressure is adjusted by the bypass passage 132 and the waste gate valve 133. That is, as described above, the supercharging turbine 64 is a fixed capacity turbine, and the flow path area of the exhaust gas flowing into the impeller 64a of the supercharging turbine 64 is fixed. Therefore, in order to adjust the rotational force of the impeller 64a and thus the supercharging pressure, it is necessary to adjust the amount of exhaust flowing into the impeller 64a, and the amount of exhaust is adjusted by changing the opening degree of the wastegate valve 133. .

  Specifically, the wastegate valve 133 is a low-speed, high-load engine whose engine speed is less than the reference speed N1, as shown in FIG. 3, in the high load region A1 (see FIG. 4) where the engine load is equal to or higher than the reference load T1. In the region A1_L, the valve is fully closed, and in the high-speed and high-load region A1_H of the reference rotation speed N1 or higher, the valve is opened. In the high-speed and high-load region A1_H, basically, the opening degree of the wastegate valve 133 is increased (opened) as the engine speed increases.

  That is, in order to increase the supercharging pressure in a region where the engine speed is low and the exhaust flow rate is small, it is necessary to cause more of the exhaust discharged from the engine body 1 to flow into the supercharging turbine 64. Therefore, in the low speed and high load region A1_L where high engine pressure is required while the engine speed is low, the wastegate valve 133 is fully closed and the entire amount of exhaust discharged from the engine body 1 is supplied to the turbocharger turbine 64. be introduced. On the other hand, in the high speed and high load region A1_H where the engine speed is high and the flow rate of the exhaust gas is large, the supercharging pressure becomes excessively high when the entire amount of exhaust gas flows into the supercharging turbine 64. Then, the waste gate valve 133 is opened, and a part of the exhaust gas is led to the downstream side by bypassing the supercharging turbine 64.

  As shown in FIG. 4, the high load area A1 is an area including the entire load, and the reference load T1 is set to a value lower by a predetermined load from the maximum value of the engine load at each engine speed. Is set.

  Here, in the present embodiment, the turbine efficiency η_T and the compressor efficiency η_C of the supercharging turbine 64 in the high load region A1 are set as shown in FIG. That is, the turbine efficiency η_T is maximized in the low speed and high load region A1_L where the wastegate valve 133 is fully closed, and the compressor efficiency η_C is maximized in the high speed and high load region A1_H where the wastegate valve 133 is opened. Is set to

  Specifically, as shown in FIG. 5, the turbine efficiency η_T in the high load region A1 increases as the engine speed increases, and after the engine speed reaches the maximum at the first speed N11, The first rotational speed N11 is set so as to be gradually lowered as the rotational speed is increased, and to be less than the reference rotational speed N1.

  On the other hand, as shown in FIG. 5, the compressor efficiency η_C in the high load region A1 increases as the engine speed increases, and after the engine speed reaches the maximum at the second speed N12, The second rotational speed N12 is set so as to be gradually lowered with the increase and to be equal to or higher than the reference rotational speed N1.

  Further, in the present embodiment, the compressor efficiency η_C is set so as to exceed the turbine efficiency η_T in the high-speed and high-load region A1_H having the reference rotational speed N1 or more. That is, both the turbine efficiency η_T and the compressor efficiency η_C become the same reference efficiency η_0 at the third rotation speed N13 that is equal to or higher than the reference rotation speed N1, and the turbine efficiency η_T exceeds the reference efficiency η_0 when the engine rotation speed exceeds the third rotation speed N13. On the other hand, the compressor efficiency η_C increases more than the reference efficiency η_0.

(3) Control System A control system of the engine system 100 will be described with reference to FIG. The engine system 100 of the present embodiment is controlled by an ECU (engine control unit, control means) 500 mounted on the vehicle. As is well known, ECU 500 is a microprocessor including a CPU, ROM, RAM, I / F, and the like.

  ECU 500 receives information from various sensors. For example, the ECU 500 is provided in the vehicle, an engine speed sensor SN1 for detecting the rotation speed of the crankshaft 106, that is, the rotation speed of the engine body 1, an air flow sensor SN2 for detecting the amount of intake air flowing into the engine body 1. An accelerator opening sensor SN3 that detects the opening of an accelerator pedal (not shown) that is operated by the driver, and a supercharging pressure sensor that detects the supercharging pressure of the compressor 62 as a pressure amount downstream of the compressor 62 It is electrically connected to SN4 and the like and receives input signals from these sensors. In addition, the battery voltage and operation signals of various electric devices are also input to the ECU 500.

  The ECU 500 executes various calculations based on the input signals from the sensors SN1 to SN4 and the like, and generates the generator driving device 75, the waste gate valve 133, the ISG driving device 85, and other parts of the engine (the spark plug 18, the injector). 105, the throttle valve 123, etc.), respectively. Specifically, ECU 500 outputs a control signal to an actuator that opens and closes wastegate valve 133 to control the opening degree thereof.

  A control procedure of the waste gate valve 133, the generator 72 (generator driving device 75), and the engine-side generator 82 by the ECU 500 will be described with reference to the flowchart of FIG. Here, these control procedures in the high load region A1 will be described.

  First, in step S1, the controller 500 reads the engine speed detected by the engine speed sensor SN1, the accelerator opening detected by the accelerator opening sensor SN5, the SOC that is the remaining battery level, and the like. The SOC is detected from a current sensor or the like connected to the battery.

  Next, in step S2, it is determined whether or not the high-speed and high-load region A1_H.

  When the determination in step S2 is YES and the engine body 1 is operating in the high speed and high load region A1_H, the process proceeds to step S3 and the waste gate valve (W / G) 133 is opened. At this time, as described above, the wastegate valve 133 has a larger opening degree as the engine speed increases. On the other hand, if the determination in step S3 is NO, the process proceeds to step S4, and the waste gate valve 133 is closed (in the present embodiment, it is fully closed). After steps S3 and S4, the process proceeds to step S5.

  In step S5, it is determined whether or not there is a power generation request for the generator 72.

  Specifically, the controller 500 calculates the amount of power that is currently insufficient with respect to a predetermined amount of power based on the SOC, the electrical load of various electrical devices, and the like, and if the amount of power shortage is greater than or equal to a predetermined value. It is determined that there is a power generation request. The predetermined amount of power is, for example, the maximum amount of power stored in the battery, and is calculated by subtracting the current amount of power stored in the battery and the amount of power consumed by various electric devices from the maximum amount of stored power.

  If the determination in step S5 is NO and there is no power generation request, the process proceeds to step S10.

  In step S10, power generation by the turbine-side generator 72 is stopped. Specifically, the generator driving device 75 stops applying the magnetization current to the rotor coil of the generator 72. After step S10, the process proceeds to step S8.

  On the other hand, if the determination in step S5 is YES and there is a power generation request, the process proceeds to step S6.

  In step S6, it is determined whether the power generation request is high. Specifically, when the power shortage amount is larger than the reference shortage amount set to a value higher than the predetermined value, and the power is largely insufficient (relative to the predetermined power amount), the power generation emergency It is determined that the power generation demand is high. For example, this determination is YES when the SOC has dropped below a predetermined value and there is a possibility that power shortage will soon occur (a state in which necessary electrical equipment cannot be operated normally) unless power generation is performed.

  If the determination in step S6 is YES and the power generation request level for power generation is high and it is necessary to urgently generate power, the process proceeds to step S7.

  In step S7, power generation by the turbine-side generator 72 is performed. Specifically, the generator driving device 75 applies a magnetization current to the rotor coil of the generator 72. After step S7, the process proceeds to step S8.

  On the other hand, if the determination in step S6 is no, the process proceeds to step S12.

  In step S12, it is determined whether or not the specific region R1.

  Here, the specific region R1 is a region including the engine speed at which the compressor efficiency η_C is maximum in the high speed and high load region A1_H. In the present embodiment, as shown in FIG. 5, the specific region R1 is set in a region where the compressor efficiency η_C is equal to or higher than the reference efficiency η_0. That is, the specific region R1 is the fourth rotation in which the compressor efficiency η_C becomes the reference efficiency η_0 in the region where the engine speed is equal to or higher than the third speed N13 and higher than the second speed N12 in the high load area A1. The area is set to a number N14 or less.

  In step S12, it is determined whether or not the engine body 1 is operated in the specific region R1 set in this way.

  If the determination in step S12 is YES and the vehicle is operating in the specific region R1, the process proceeds to step S13. In step S13, power generation by the turbine generator 72 is performed. After step S13, the process proceeds to step S8.

  On the other hand, if the determination in step S12 is no, the process proceeds to step S14.

  In step S14, it is determined whether it is the second specific region R2.

  As shown in FIG. 4, the second specific region R2 is a region where the engine load is less than the specific region R1 and is set to the same engine speed region as the specific region R1. That is, the second specific region R2 is a region where the engine load is less than the reference load T1 and the engine speed is not less than the third speed N13 and not more than the fourth speed N14.

  If the determination in step S14 is no, the process proceeds to step S10. Then, as described above, the power generation by the turbine-side generator 72 is stopped.

  On the other hand, when the determination in step S14 is YES and the engine body 1 is being operated in the second specific region R2, the process proceeds to step S15. And in step S15, while performing the electric power generation (ISG electric power generation) by the engine side generator 82, the electric power generation by the turbine side generator 72 is implemented. At this time, the power generation amount of the engine-side generator 82 is controlled to an amount capable of operating the engine body 1 in the specific region R1 by increasing the engine load to the reference load T1 or more. That is, if the engine-side generator 82 is driven, a rotational load is applied to the engine body 1 (crankshaft 106), and the engine load increases. Therefore, in step S15, power generation by the engine-side generator 82 is performed, and power generation by the turbine-side generator 72 is performed while shifting the operating point of the engine body 1 to the specific region R1.

  After step S15, the process proceeds to step S8.

  In step S8, it is determined whether or not the supercharging pressure is the target supercharging pressure that is the target value. The target boost pressure is determined from the engine speed, engine load, and the like. For example, the target boost pressure is set for the engine speed and the engine load. The controller 500 stores a target boost pressure for the engine speed and the engine load as a map, and extracts a value corresponding to the current engine speed and the engine load as a target boost pressure from the map. .

  If the determination in step S8 is YES and the supercharging pressure is the target supercharging pressure, the processing is terminated as it is.

  On the other hand, when determination of step S8 is NO, it progresses to step S9 and the opening degree of the wastegate valve 133 is adjusted. Then, the process ends. Specifically, when the supercharging pressure is lower than the target supercharging pressure, the wastegate valve 133 is corrected to the closed side, and when the supercharging pressure is higher than the target supercharging pressure, the wastegate valve 133 is opened. Correct to the side. Note that when the wastegate valve 133 is fully closed, the wastegate valve 133 cannot be closed any further, and in this case, the wastegate valve 133 is maintained fully closed.

  In step S8, the supercharging pressure is not limited to the case where the supercharging pressure completely matches the target supercharging pressure, but the supercharging pressure is set to the target when the difference between the supercharging pressure and the target supercharging pressure is equal to or less than a predetermined value. It may be determined that it matches the supercharging pressure.

(4) Operation, etc. As described above, even in the specific region R1, even when the level of power generation request is low and the urgency level of power generation is low compared to other regions (even when the amount of power shortage is small). As soon as there is a demand for power generation, power generation is carried out. That is, in the engine system 100, when the engine is operating in the specific region R1, power generation is performed with higher priority than when the engine is operating in another region.

  Here, the specific region R1 is included in the high-speed and high-load region A1_H, and is a region where the waste gate valve 133 is opened. Therefore, in the specific region R1, power generation can be performed using exhaust gas that has not been used for supercharging, and power generation can be performed while increasing the supercharging pressure. Therefore, power generation is performed preferentially in the specific region R1, so that a power generation amount can be ensured while maintaining a high supercharging pressure.

  In addition, as described above, the specific region R1 is set to a region including the engine speed at which the compressor efficiency η_C is higher than the reference efficiency η_0 and the compressor efficiency η_C is maximized. Therefore, the pumping loss can be further reduced while securing the power generation amount.

  Specifically, when a load is applied to the power generation turbine 74 to generate power with the generator 72, the pressure on the upstream side of the power generation turbine 74, that is, the pressure on the downstream side of the supercharging turbine 64 increases. Therefore, in order to maintain the supercharging pressure at a high pressure during power generation, the pressure on the upstream side of the supercharging turbine 64 needs to be further increased, and the back pressure of the engine body 1 may be excessively increased. is there. On the other hand, as described above, since the compressor efficiency η_c is set high in the specific region R1, the pressure ratio of the supercharging turbine 64 (the pressure between the upstream pressure and the downstream pressure of the supercharging turbine) The supercharging pressure can be increased while keeping the ratio) small. That is, during power generation by the generator 72, it is possible to suppress an excessive increase in the pressure on the upstream side of the turbocharging turbine 64 and the back pressure of the engine body 1 while increasing the supercharging pressure. Therefore, it is possible to suppress the pumping loss from being excessively deteriorated with the power generation. Therefore, it is possible to increase the fuel pressure performance while increasing the supercharging pressure and securing the power generation amount.

  Further, in the engine system 100, the turbine efficiency η_T is set to be maximum in the low speed and high load region A1_L. For this reason, a fixed capacity turbine is used as the supercharging turbine 62, and the supercharging pressure can be appropriately increased even in the low speed and high load region A1_L while keeping the cost lower than when using a variable capacity turbine. That is, in the low speed and high load region A1_L, it is difficult to increase the supercharging pressure because the engine speed is low and the flow rate of the exhaust gas is small. In particular, in the fixed capacity turbine, unlike the variable capacity turbine, it is difficult to increase the supercharging pressure in the low speed and high load region A1_L because the flow area of the exhaust gas flowing into the impeller 64a and the flow velocity of the exhaust gas cannot be changed. On the other hand, in the present embodiment, the turbine efficiency is increased in the low speed and high load region A1_L, thereby suppressing an excessive increase in the pressure on the upstream side of the supply turbine 64 with a small exhaust flow rate. However, the boost pressure can be effectively increased. Therefore, in this engine system 100, it is possible to improve the fuel efficiency by suppressing the pumping loss while increasing the boost pressure over a wider range.

  In the engine system 100, when the engine body 1 is operated in the specific region R2, that is, when the engine load is less than the reference load T1, the engine speed is the engine speed corresponding to the specific region R1. As described above, power is generated by the engine generator 82, and power is generated by the turbine generator 72 while the operating point of the engine body 1 is shifted to the specific region R1. Therefore, it is possible to increase the power generation opportunities in the specific region R1, and it is possible to secure a larger amount of power generation while suppressing deterioration of fuel efficiency and increasing the supercharging pressure. In particular, at this time, power is also generated by the engine-side generator 82. Therefore, the amount of power generation can be further increased.

(5) Modification In the above embodiment, the specific region R1 where power generation is preferentially performed has been described as being only a part of the high speed and high load region A1_H, but the specific region R1 is included in the high speed and high load region A1_H. It is only necessary to set the region including the second engine speed at which the compressor efficiency η_C is maximized. For example, the entire high speed and high load region A1_H may be set to the specific region R1.

  The engine generator 82 can be omitted.

  Moreover, although the said embodiment demonstrated the case where a battery was used as a means to store electric power, you may make it store electric power using means other than a battery.

  Further, instead of the power shortage amount, it may be configured that it is determined that there is a power generation request when the power consumption in the electric equipment exceeds a predetermined value.

  Further, the generator 72 is only required to be driven by the power generation turbine 74 and switch between the generation and the stop of the power generation, and the specific configuration is not limited to the above. For example, the power generation in the generator may be stopped by releasing the connection between the generator and the power generation turbine.

  Moreover, although the said embodiment demonstrated the case where the engine main body 1 was a 4-cylinder gasoline engine, the kind of engine main body 1 is not restricted to this. For example, a diesel engine or an engine having another number of cylinders may be used.

1 Engine body 62 Compressor 64 Turbocharged turbine 72 Generator (turbine-side generator)
74 Turbine for power generation 82 Engine-side generator 100 Engine system (engine with turbocharger)
120 Intake passage 130 Exhaust passage 132 Bypass passage 133 Wastegate valve (open / close valve)
500 ECU (control means)
R1 specific area R2 second specific area

Claims (3)

A turbocharged engine,
The engine body,
An intake passage and an exhaust passage connected to the engine body;
A turbocharger including a compressor provided in the intake passage and a supercharging turbine provided in the exhaust passage;
A power generation device including a power generation turbine that is provided downstream of the supercharging turbine in the exhaust passage and rotates by receiving energy of exhaust, and a turbine side generator that is driven by the power generation turbine to generate power;
Control means capable of controlling each part of the engine including the turbine-side generator,
The exhaust passage includes a bypass passage that bypasses the supercharging turbine and introduces exhaust gas into the power generation turbine, and an open / close valve that opens and closes the bypass passage;
The supercharging turbine includes an impeller that has a plurality of blades and rotates by receiving the energy of exhaust, and a housing that houses the impeller and has a constant flow area of the exhaust flowing into the impeller. Prepared,
In a high load region where the engine load is equal to or higher than the reference load, the turbine efficiency of the supercharging turbine is set so that the engine speed is maximized at a speed less than a preset reference speed, The compressor efficiency is set so that the engine speed becomes maximum at a speed higher than the reference speed,
The control means includes
When the engine speed is less than the reference speed in the high load area, the on-off valve is fully closed. On the other hand, in the high speed and high load area where the engine speed is equal to or higher than the reference speed in the high load area, the on-off valve is closed. As well as
When the engine is operated in a specific region including at least the engine speed at which the compressor efficiency is maximized in the high-speed and high-load region, and when there is a power generation request for the generator, the generator generates power. Let
With a turbocharger, wherein the engine is operated in an operation region other than the specific region, and when there is a power generation request, power generation by the generator is performed or stopped depending on conditions engine. In the turbocharged engine according to claim 1,
The efficiency of the compressor is set so as to increase as the engine speed increases and exceed the efficiency of the supercharging turbine at a predetermined engine speed,
The turbocharged engine is characterized in that the specific region is set to a region in the high-speed and high-load region where the compressor efficiency is equal to or higher than the efficiency at the predetermined engine speed. The turbocharged engine according to claim 1 or 2,
An engine-side generator that generates power by being connected to the output shaft of the engine body and driven to rotate by the output shaft;
When the engine is operated in a region on a lower load side than the specific region and there is a power generation request for the generator, the control means is configured so that the engine load becomes a load in the specific region. A turbocharged engine characterized by driving a side generator.