CN113302101A

CN113302101A - Hybrid system, control device for hybrid system, and control method for hybrid system

Info

Publication number: CN113302101A
Application number: CN201980089171.7A
Authority: CN
Inventors: 本城文纪
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2019-01-17
Filing date: 2019-12-19
Publication date: 2021-08-24
Anticipated expiration: 2039-12-19
Also published as: WO2020149100A1; JP2020114688A; JP7213445B2; TW202031537A; TWI734345B; CN113302101B

Abstract

The hybrid system is provided with: an engine (20); an MG (32) that generates electric power using power output from the engine (20); a battery (10) that charges generated power obtained by the MG (32); an MG (31) for driving the vehicle (100), which is driven using at least one of the discharge power of the battery (10) and the generated power obtained by the MG (32); and a control device (52, 51, 11). The control device (52, 51, 11) controls to limit at least one of the rate of change of the target rotation speed and the rate of change of the target output torque of the engine (20) (S103-S105).

Description

Hybrid system, control device for hybrid system, and control method for hybrid system

Technical Field

The present disclosure relates to a hybrid system, a control device for a hybrid system, and a control method for a hybrid system, and more particularly to a hybrid system mounted on a vehicle driven by a motor using electric power generated by power of an internal combustion engine, a control device for a hybrid system, and a control method for a hybrid system.

Background

Conventionally, there is a hybrid vehicle having the following structure: the control is performed so as to keep the load of the engine during acceleration constant (see, for example, patent document 1). In the vehicle Of patent document 1, the soc (state Of charge) Of the battery is increased by traveling while regenerating the engine-surplus output by the motor generator at the initial stage Of acceleration. The second half of acceleration is performed while assisting the engine with insufficient output by using the electric power of the battery generated by the motor generator. By controlling in this way, the generation of smoke can be suppressed.

Patent document 1: japanese laid-open patent publication No. 2005-194886

However, in the vehicle of patent document 1, it is necessary to rapidly increase the load immediately before the load of the engine is kept constant. Therefore, the emission amounts of smoke (black smoke) and NOx (nitrogen oxide) are deteriorated due to the supercharging hysteresis. Further, when the vehicle is accelerated suddenly while the load of the engine is kept constant, the rotation speed of the engine also needs to be increased suddenly, and therefore, the emission amount of smoke and NOx is also deteriorated due to the supercharging hysteresis.

Disclosure of Invention

The present disclosure has been made to solve the above-described problems, and an object thereof is to provide a hybrid system, a control device for the hybrid system, and a control method for the hybrid system, which are capable of reducing the emission amounts of soot and nitrogen oxides.

The disclosed hybrid system is provided with: an internal combustion engine; a generator that generates electric power using power output from the internal combustion engine; a power storage device that charges generated power obtained by the generator; a vehicle-driving electric motor that is driven using at least one of electric power discharged from the power storage device and electric power generated by the generator; and a control device that controls to restrict at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.

Preferably, the control device restricts at least one of a rate of change of the target rotation speed and a rate of change of the target output torque of the internal combustion engine to be smaller than at least one of a rate of change of the black smoke emission to be larger than a1 st predetermined amount and a rate of change of the nitrogen oxide emission to be larger than a2 nd predetermined amount.

More preferably, the control device controls at least one of a rate of change of the target rotation speed and a rate of change of the target output torque of the internal combustion engine using a predetermined control map.

More preferably, the control device controls at least one of the rate of change in the target rotation speed of the internal combustion engine and the rate of change in the target output torque to be relatively smaller when the SOC of the power storage device is higher than a predetermined value, as compared to when the SOC of the power storage device is lower than the predetermined value.

More preferably, the control map comprises: the mapping of the rotating speed can be determined according to the request power to the generator and the vehicle speed; and a map capable of determining a target output torque from the requested electric power to the generator and the target rotation speed.

More preferably, the control map includes a region that gives priority to control of limiting at least one of the rate of change in the target rotation speed and the rate of change in the target output torque of the internal combustion engine in the power generation ratio.

A control device for a hybrid system according to another aspect of the present disclosure is a control device for controlling a hybrid system including: an internal combustion engine; a generator that generates electric power using power output from the internal combustion engine; a power storage device that charges generated power obtained by the generator; and a motor for driving the vehicle, which is driven using at least one of the electric power discharged from the power storage device and the electric power generated by the generator. The control device controls to restrict at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.

A control method of a hybrid system according to still another aspect of the present disclosure is a control method of a control device for controlling a hybrid system, the hybrid system including: an internal combustion engine; a generator that generates electric power using power output from the internal combustion engine; a power storage device that charges generated power obtained by the generator; and a motor for driving the vehicle, which is driven using at least one of the electric power discharged from the power storage device and the electric power generated by the generator. The control method comprises the following steps: the control device controls to restrict at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.

According to the present disclosure, at least one of the rate of change of the target rotation speed of the internal combustion engine and the rate of change of the target output torque in the hybrid system is limited. As a result, it is possible to provide a hybrid system, a control device for a hybrid system, and a control method for a hybrid system, which can reduce the amount of emission of soot and nitrogen oxides.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a vehicle according to this embodiment.

Fig. 2 is a flowchart showing a flow of the engine control process according to the embodiment.

Fig. 3 is a diagram showing a flow of calculation of the target engine speed of the engine according to the embodiment.

Fig. 4 is a diagram showing a calculation flow of the target output of the engine according to the embodiment.

Fig. 5 is a diagram showing an engine speed basic map of the embodiment.

Fig. 6 is a diagram showing an engine speed correction basic map of the embodiment.

Fig. 7 is a diagram showing a target rotation speed SOC correction coefficient map according to this embodiment.

Fig. 8 is a diagram showing a relaxation coefficient map according to this embodiment.

Fig. 9 is a diagram showing a minimum engine speed map of the embodiment.

Fig. 10 is a diagram showing an engine target output basic map according to the embodiment.

Fig. 11 is a diagram showing a target output SOC correction coefficient map according to this embodiment.

Fig. 12 is a diagram showing a relaxation coefficient map according to this embodiment.

Fig. 13 is a diagram showing example 1 of the control result of the embodiment.

Fig. 14 is a diagram showing an example 2 of the control result of the embodiment.

Fig. 15 is a diagram showing example 3 of the control result of the embodiment.

Fig. 16 is a diagram showing an example 1 of the overall control result of the embodiment.

Fig. 17 is a diagram showing an example 2 of the overall control result of the embodiment.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

Fig. 1 is a diagram showing a schematic configuration of a vehicle 100 according to this embodiment. Referring to fig. 1, vehicle 100 includes a battery 10, a power Control unit (hereinafter referred to as "pcu (power Control unit")) 11, an engine 20, a motor generator (hereinafter referred to as "MG (motor generator")) 31, an MG32, and drive wheels 40. The vehicle 100 further includes various Electronic Control Units (ECU) such as HV-ECU51 and EG-ECU52, which will be described later. The battery 10 according to the present embodiment corresponds to an example of the "power storage device" according to the present disclosure.

The engine 20 is an internal combustion engine that outputs power by converting combustion energy generated when fuel (gasoline, light oil, etc.) is combusted into kinetic energy of a moving object such as a piston or a crankshaft. The MG31 and the MG32 are electric power devices that convert electric energy into mechanical energy, or convert mechanical energy into electric energy. In the present embodiment, a diesel engine is used as the engine 20, and three-phase ac synchronous motor generators in which permanent magnets are embedded in a rotor are used as the MG31 and the MG 32. The engine 20 may be provided with a turbocharger (e.g., a variable nozzle worm wheel) in the intake/exhaust system.

The vehicle 100 according to the present embodiment is a series hybrid vehicle. In the vehicle 100, the MG31 (running motor) operates as an electric motor to drive the drive wheels 40, and the MG32 is driven by the engine 20 to generate electric power. The power sources for driving the MG31 are electric power generated by the MG32 and electric power stored in the battery 10. More specifically, the rotary shaft 21 of the engine 20 and the rotary shaft 22 of the MG32 are mechanically coupled to each other via the gear 23, and the rotary shaft 22 of the MG32 rotates with the rotation of the rotary shaft 21 of the engine 20, whereby the MG32 generates electric power. On the other hand, the rotary shaft 41 of the MG31 is not mechanically coupled to the

rotary shafts

21 and 22, but is mechanically coupled to the drive shaft 42 via the power transmission gear 43. The torque (driving force) output to the rotary shaft 41 of the MG31 is transmitted to the drive shaft 42 via the power transmission gear 43, and the drive shaft 42 is rotated by the driving force of the MG 31. Then, the drive shaft 42 rotates, thereby rotating the drive wheels 40 provided at both ends of the drive shaft 42.

MG31 operates as a motor when vehicle 100 accelerates, and drives drive wheels 40 of vehicle 100. On the other hand, when vehicle 100 is braked or the acceleration of a downhill decreases, MG31 operates as a generator to perform regenerative power generation. The electric power generated by MG31 is supplied to battery 10 via PCU 11.

MG32 is configured to generate electric power using power output from engine 20 (engine power generation). The engine-generated electric power generated in the MG32 is supplied from the MG32 to the MG31, or is supplied from the MG32 to the battery 10 via the PCU 11.

The PCU11 is configured to include two inverters provided corresponding to the MG31 and the MG32, and a boost converter that boosts a dc voltage supplied to each inverter to a voltage equal to or higher than the voltage of the battery 10 (e.g., 600V). The PCU11 performs power conversion between the battery 10 and the MG31 and the MG32 in accordance with a control signal from the HV-ECU 51. The PCU11 is configured to be able to control the states of the MG31 and the MG32, respectively.

The battery 10 is a dc power supply capable of secondary charging. The rated voltage of the battery 10 is, for example, 300V to 450V. The battery 10 is configured to include, for example, a secondary battery (a battery capable of secondary charging). As the secondary battery, for example, a lithium ion battery can be used. Battery 10 may also include a battery pack composed of a plurality of secondary batteries (e.g., lithium ion batteries) connected in series and/or parallel. The secondary battery constituting the battery 10 is not limited to a lithium ion battery, and other secondary batteries (e.g., a nickel hydrogen battery) may be used. An electrolytic solution type secondary battery may be used, or an all-solid secondary battery may be used. In addition, a capacitor having a large capacity or the like may be used as the battery 10.

The battery 10 is provided with a monitoring unit 61 that monitors the state of the battery 10. The monitoring unit 61 includes various sensors that detect the states (temperature, current, voltage, and the like) of the battery 10. The HV-ECU51 is configured to detect the state (SOC, etc.) of the battery 10 based on the output of the monitoring unit 61. The soc (state Of charge) indicates the remaining battery level, and represents, for example, a ratio Of the current amount Of stored power to the amount Of stored power in the fully charged state by 0 to 100%. Various known methods such as a method of integrating a current value (coulomb count) and a method of estimating an Open Circuit Voltage (OCV) can be used as a method of measuring the SOC.

Further, a monitoring unit 62 that monitors a state of the engine 20 is provided to the engine 20. The monitoring unit 62 includes various sensors that detect the state of the engine 20 (cooling water temperature, intake air amount, rotation speed, and the like). The HV-ECU51 and the EG-ECU52 are configured to detect the state of the engine 20 based on the output of the monitoring unit 62.

In addition, for the MG31 and the MG32, monitoring

units

63, 64 that monitor the states of the MG31 and the MG32, respectively, are provided. The

monitoring units

63, 64 include various sensors that detect the states (temperature, rotation speed, etc.) of the MG31 and the MG 32. The HV-ECU51 is configured to detect the states of the MG31 and the MG32 based on the outputs of the

monitoring units

63, 64.

Each ECU (HV-ECU51, EG-ECU52) included in vehicle 100 includes a cpu (central Processing unit) as an arithmetic device, a storage device, and input/output ports (both not shown) for inputting and outputting various signals. The storage device includes a ram (random Access memory) as a working memory, a storage memory (rom (read Only memory), a rewritable nonvolatile memory, and the like). Each ECU receives signals from various devices (sensors and the like) connected to the input port, and controls various devices connected to the output port based on the received signals. Various controls are executed by the CPU executing programs stored in the storage device. However, the control performed by each ECU is not limited to the processing performed by software, and may be performed by dedicated hardware (electronic circuit). The HV-ECU51 and the EG-ECU52 according to the present embodiment function as "control devices" according to the present disclosure.

The HV-ECU51 calculates an output request value for the engine 20 and output request values (e.g., torque request values) for the MG31 and the MG 32. Also, the HV-ECU51 transmits an output request value for the engine 20 to the EG-ECU52, and controls power supply to the MG31 and the MG32 (further, output torques of the MG31 and the MG 32) based on the output request values for the MG31 and the MG 32. The HV-ECU51 can control the magnitude (amplitude), frequency, and the like of the electric power supplied to the MG31 and the MG32 by controlling the PCU11 and the like. The HV-ECU51 controls the PCU11 and the like to control charging and discharging of the battery 10.

The various devices connected to the input port of the HV-ECU51 include an accelerator opening sensor 65 and a vehicle speed sensor 66 in addition to the various sensors included in the

monitoring units

61, 63, 64.

The accelerator opening sensor 65 detects a depression amount of an accelerator pedal (not shown) of the vehicle 100 as an accelerator opening, and outputs a detection result (a signal indicating the accelerator opening) to the HV-ECU 51. The greater the amount of depression of the accelerator pedal, the greater the driving force of the MG31 for the HV-ECU 51.

The vehicle speed sensor 66 detects the speed of the vehicle 100, and outputs the detection result (signal indicating the vehicle speed) to the HV-ECU 51.

The EG-ECU52 performs operation control (fuel injection control, ignition control, intake air amount adjustment control, etc.) of the engine 20 so as to receive an output request value for the engine 20 from the HV-ECU51 and generate kinetic energy corresponding to the output request value by the engine 20. The engine power generation is performed by driving the engine 20, and when the engine power generation is not performed, the engine 20 is stopped. By driving the engine 20, engine generated electric power is generated in the MG 32. The EG-ECU52 receives detection values of various sensors included in the monitoring unit 62, and transmits the detection values to the HV-ECU 51.

The vehicle 100 travels by the MG31 driving the drive wheels 40. The HV-ECU51 starts charging the battery 10 by the engine generated power when the SOC of the battery 10 becomes equal to or less than the charge start SOC while the vehicle 100 is traveling, and stops the charging when the SOC of the battery 10 becomes equal to or more than the charge end SOC.

When the SOC of the battery 10 is equal to or less than the charge start SOC and the battery 10 is charged by the engine generated power, the HV-ECU51 requests the EG-ECU52 to drive the engine 20 under a predetermined condition suitable for power generation, and the EG-ECU52 controls the engine 20 in response to the request, thereby generating the engine generated power larger than the power consumed during the traveling of the vehicle 100 by the MG 32. The HV-ECU51 controls the PCU11 and the like to supply the generated engine generated power to the battery 10. Thereby, the battery 10 is charged with the engine generated power, and the SOC of the battery 10 increases.

When the SOC of the battery 10 is equal to or greater than the charge completion SOC, the HV-ECU51 instructs the EG-ECU52 to stop the engine 20, and controls the PCU11 and the like to stop the supply of electric power to the battery 10.

In this way, during the running of vehicle 100, engine 20 is started every time the SOC of battery 10 becomes equal to or less than the charge start SOC, and the charging of battery 10 based on the engine generated power is executed. Thereby, the SOC of the battery 10 is maintained substantially within the range of the charge start SOC or more and the charge end SOC or less.

In the present embodiment, the vehicle 100 includes a dpf (diesel Particulate filter)71 and an nsr (nox Storage reduction) catalyst 72 as devices for treating exhaust gas of the engine 20. The engine 20, DPF71, and NSR catalyst 72 are connected by exhaust pipes, respectively.

An exhaust pipe between the engine 20 and the DPF71 is provided with an exhaust gas temperature sensor 81 and an a/F sensor 82. The exhaust gas temperature sensor 81 detects the temperature of the exhaust gas from the engine 20, and outputs the detection result (a signal indicating the exhaust gas temperature) to the EG-ECU 52. The a/F sensor 82 detects an air-fuel ratio by analyzing exhaust gas from the engine 20, and outputs the detection result (a signal indicating the air-fuel ratio) to the EG-ECU 52.

The DPF71 is a filter that collects Particulate Matter (PM) contained in exhaust gas flowing through an exhaust passage of the engine 20. The collected PM is accumulated inside the DPF 71. Therefore, the DPF71 is regenerated by periodically bringing the inside of the DPF71 to a high temperature to burn and remove the PM.

The NSR catalyst 72 is an NOx catalyst of the absorption storage reduction type, and is formed, for example, from alumina (Al)₂O₃) The carrier is a carrier, and for example, a basic metal such as potassium (K), sodium (Na), lithium (Li), or cesium Cs, an alkaline earth such as barium Ba or calcium Ca, a rare earth such as lanthanum (La) or yttrium (Y), or a noble metal such as platinum Pt is supported on the carrier.

The NSR catalyst 72 absorbs NOx in a state where a large amount of oxygen is present in the exhaust gas, the oxygen concentration in the exhaust gas is low, and NOx is reduced to NO in a state where a large amount of reducing component (for example, unburned component (HC) of fuel) is present₂Or NO and released. As NO₂NOx released from NO reacts rapidly with HC and CO in the exhaust gas and is further reduced to N₂. By reducing NO for HC and CO₂NO, by itself oxidized to H₂O、CO₂. That is, if the oxygen concentration and HC component in the exhaust gas introduced into the NSR catalyst 72 are appropriately adjusted, HC, CO, and NOx in the exhaust gas can be purified.

An NOx sensor 83 is provided in the exhaust pipe downstream of the NSR catalyst 72. The NOx sensor 83 detects the amount of NOx contained in the exhaust gas discharged from the NSR catalyst 72, and outputs the detection result (a signal indicating the amount of NOx) to the EG-ECU 52.

In the hybrid system mounted on vehicle 100 driven by MG31 using electric power generated by the motive power Of engine 20, when the load on engine 20 during acceleration is controlled to be constant, soc (state Of charge) Of battery 10 is increased by traveling while the excess output Of engine 20 is regenerated by MG32 in the initial stage Of acceleration. In the second half of acceleration, the vehicle travels while assisting the insufficient output of the engine 20 with the power of the battery 10 by the MG 31. By controlling in this way, the generation of smoke can be suppressed.

However, immediately before the load of the engine 20 is kept constant, the load needs to be increased sharply. Therefore, the smoke and NOx emissions are deteriorated due to the supercharging hysteresis. When the vehicle 100 is accelerated suddenly while the load of the engine 20 is kept constant, the rotation speed of the engine 20 must be increased suddenly, and the amount of smoke and NOx discharged is also deteriorated due to the supercharging delay.

Therefore, in this embodiment, the HV-ECU51 and the EG-ECU52 are controlled so as to limit the target rotation speed of the engine 20 and the rate of change in the target output torque. This can reduce the amount of smoke and NOx emitted.

Fig. 2 is a flowchart showing a flow of the engine control process according to the embodiment. This engine control process is called from the start of the main process every predetermined control cycle, and executed by the EG-ECU 52. Referring to fig. 2, the EG-ECU52 calculates the required power for power generation by the MG32 based on the vehicle speed, SOC, accelerator pedal position, and the like (step (hereinafter referred to as "S") 101). The requested electric power is electric power required to drive the vehicle 100 according to the accelerator opening degree or the like. When the SOC of the battery 10 exceeds the charge completion SOC, the requested electric power becomes 0. As a result, the engine 20 is stopped. When the SOC of the battery 10 is lower than the charge start SOC, the requested power is calculated and a power generation request is issued.

Next, the EG-ECU52 determines whether there is a power generation request, in other words, whether the requested power is not 0 (S102). When determining that there is no power generation request (no in S102), the EG-ECU52 returns the executed process to the calling source of the process.

On the other hand, when it is determined that there is a power generation request (yes in S102), the EG-ECU52 calculates a target rotation speed of the engine 20 from the vehicle speed and the requested power (S103). The calculation of the target rotation speed will be described with reference to fig. 3 described later. Next, the EG-ECU52 calculates a target output of the engine 20 based on the target rotation speed and the vehicle speed (S104). The calculation of the target output will be described with reference to fig. 4 described later. The EG-ECU52 controls the engine 20 so that the calculated target rotation speed and target output are achieved (S105), and the EG-ECU52 returns the executed processing to the original calling processing of the processing.

The control of the rotation speed and output of the engine 20 is performed by controlling the rotation speed with the MG32, for example. Specifically, when the rotation speed is set to a high target rotation speed, first, PCU11 is controlled so as to reduce the amount of power generated by MG 32. Since the amount of power generation is lower than the requested power, the control is performed to increase the rotation speed of MG32, that is, the rotation speed of engine 20, in order to increase the amount of power generation. Next, the PCU11 is controlled so as to increase the amount of power generation by the MG 32. At this time, the control is performed to generate a power amount higher than the first power amount. Since the amount of power generation exceeds the requested power in this way, control is performed to reduce the rotation speed of MG32, that is, the rotation speed of engine 20, in order to reduce the amount of power generation. At this time, the control is performed to a rotation speed higher than the initial rotation speed. The PCU11 is controlled to reduce the amount of power generated by the MG 32. Then, since the amount of power generation is lower than the requested power, control is performed to increase the rotation speed of MG32, that is, the rotation speed of engine 20, in order to increase the amount of power generation. At this time, the control reaches the target rotation speed. Further, the control of the rotation speed and the output of the engine 20 may be performed by other methods.

Fig. 3 is a diagram showing a flow of calculation of the target rotation speed of engine 20 according to the embodiment. Referring to fig. 3, first, a basic rotational speed corresponding to the vehicle speed and the requested electric power is determined using an engine rotational speed basic map.

Fig. 5 is a diagram showing an engine speed basic map of the embodiment. Referring to fig. 5, in this map, the column header value is the vehicle speed, the row header value is the requested output (requested power, in other words, load applied to engine 20), and the cell value is the rotational speed. The rotation speed is set to be constant even if the requested power is changed, as long as the vehicle speed is the same. The rotation speed is set to be constant even if the vehicle speed changes in the range of 0km/h to 60km/h, and the change in the rotation speed is set to be gradually increased according to the increase in the vehicle speed when the vehicle speed is set to be 80km/h or more. In FIG. 5, A1 < A2 < A3 < A4. For example, when the vehicle speed is 60km/h and the requested power is 100kW, A1rpm is determined as the rotation speed.

When the vehicle speed was 75km/h and the requested power was 150kW, the rotation speed was determined by interpolation based on A1rpm, which is the cell values corresponding to 60km of the column header directly below 75km/h, 140kW of the row header directly below 150kW, and 160kW, and A2rpm, which is the cell values corresponding to 80km of the column header directly above 75km/h, 150kW directly below 150kW, 140kW of the column header directly above, and 160kW, and (A2-A1) × (75-60)/(80-60) + A1 was (3 × A2+ A1)/4 rpm).

Returning to fig. 3, a corrected rotation speed corresponding to the vehicle speed and the requested electric power is determined using the engine rotation speed correction basic map. The corrected rotation speed is a rotation speed used for correcting the basic rotation speed.

Fig. 6 is a diagram showing an engine speed correction basic map of the embodiment. Referring to fig. 6, in this map, the column header value is the vehicle speed, the row header value is the requested output (requested power, in other words, load applied to engine 20), and the cell value is the rotational speed. The correction rotational speed is set to be constant even if the requested power increases as long as the vehicle speed is the same. In addition, when simply adding to the value of the engine speed basic map, a value gradually increasing from A1rpm to A4rpm is set at 0km/h to 100 km/h. When the speed is 120km/h or more, B7rpm, which is smaller than B6rpm, is set. For example, when the vehicle speed is 60km/h and the requested power is 100kW, B5rpm is determined as the corrected rotational speed. If the corrected rotation speed B5rpm is simply added to the rotation speed A1rpm determined from the engine rotation speed basic map at this time, A1+ B5rpm is obtained.

Returning to fig. 3, a correction coefficient corresponding to the SOC of the battery 10 is determined using the SOC correction coefficient map. The correction coefficient is used to increase the corrected rotation speed when the SOC decreases.

Fig. 7 is a diagram showing a target rotation speed SOC correction coefficient map according to this embodiment. Referring to fig. 7, in this map, the value of the column header is SOC, the value of the row header is requested output (requested power, in other words, load applied to engine 20), and the value of the cell is a correction coefficient. Even if the requested power increases, the correction coefficient is set to be constant as long as the SOC is the same. When the SOC is 30 or less, the correction coefficient is set to be constant even if the SOC varies. When the SOC is 45 or more, the correction coefficient is set to be constant even if the SOC varies. For example, when SOC is 40% and requested power is 100kW, C2 is specified as the correction coefficient.

Returning to fig. 3, the operation is performed by adding the value obtained by multiplying the correction rotation speed specified by the engine rotation speed correction basic map of fig. 6 by the correction coefficient specified by the target rotation speed SOC correction coefficient map of fig. 7 (the operation indicated by the symbol of "x" in the figure) to the rotation speed specified by the engine rotation speed basic map of fig. 5 (the operation indicated by the symbol of "+" in the figure). For example, when the vehicle speed is 60km/h, the requested power is 100kW, and the SOC is 40%, the rotation speed A1rpm specified by the engine rotation speed basic map is added to a value obtained by multiplying the correction rotation speed B5rpm specified by the engine rotation speed correction basic map by the correction coefficient C2 specified by the target rotation speed SOC correction coefficient map, and the rotation speed becomes A1+ B5 × C2 rpm.

Next, when the rotation speed exceeds the upper limit rotation speed, calculation is performed to limit the rotation speed to the upper limit rotation speed (calculation indicated by the symbol "MIN" in the figure). For example, when the operation result indicated by the "+" sign is J1rpm and the upper limit rotation speed is 1.5 × J1, the operation result indicated by the "MIN" sign remains as it is at J1rpm since the upper limit rotation speed is not exceeded.

Next, a relaxation coefficient corresponding to the SOC of battery 10 is determined using the relaxation coefficient map. The relaxation coefficient is a coefficient for relaxing a change in the rotation speed when the SOC has a margin.

Fig. 8 is a diagram showing a relaxation coefficient map according to this embodiment. Referring to fig. 8, in this map, the value of the column header is SOC, and the value of the cell is relaxation coefficient. A relaxation coefficient is set such that the degree of relaxation increases as the SOC increases. If the SOC is set to 30 or less, D1 indicating that the relaxation coefficient is not relaxed at all is obtained. When the SOC is 50 or more, the relaxation coefficient is set to be constant even if the SOC changes (D3). For example, when the SOC is 40%, D2 is determined as the relaxation coefficient.

Returning to fig. 3, the following operations are performed: the relaxation processing is performed on the rotation speed obtained by the calculation of the upper limit rotation speed limit using the relaxation coefficient specified by the relaxation coefficient map shown in fig. 8. Here, as the relaxation process, the relaxation process is performed once, but the relaxation process may be performed twice or more. In the first relaxation processing, for example, the following operation is performed: the previous rotation speed is added to a value obtained by dividing a difference obtained by subtracting the previous rotation speed from the rotation speed obtained by the operation indicated by the symbol "MIN" described above by the relaxation coefficient. As shown in fig. 2, the calculation of fig. 3 is executed for each predetermined control cycle, but the "previous time" refers to the time before the predetermined control cycle. For example, when the relaxation coefficient is D2 corresponding to SOC 40%, the rotation speed obtained by the operation indicated by the symbol "MIN" is J2rpm, and the previous rotation speed is J2 × 9/10rpm, the (J2-J2 × 9/10)/D2+ J2 × 9/10 is (1+9 × D2) × J2/(10 × D2) rpm obtained by one operation of the relaxation processing. Thus, as the relaxation coefficient is larger than D1, the change in the rotation speed from the previous time becomes smaller.

Next, a lowest engine speed corresponding to the lowest generated power is determined using the lowest engine speed map. The minimum generated power is power obtained by subtracting the power that can be output from the battery 10 from the requested power.

Fig. 9 is a diagram showing a minimum engine speed map of the embodiment. Referring to fig. 9, in this map, the value of the column header is the lowest generated power, and the value of the cell is the lowest engine speed. The power that is insufficient to be supplied from the battery 10 for the requested power needs to be generated at a minimum. Therefore, the minimum engine speed is set to be higher as the minimum generated power is higher. The minimum engine speed is set to E3rpm when the minimum generated power is 40kW or more. If the minimum generated power is 0kW, the minimum engine speed is set to E1 (0). For example, in the case where the minimum generated power is 20kW, E2rpm is determined as the minimum engine speed.

Returning to fig. 3, when the engine speed is lower than the minimum engine speed after the calculation of the mitigation process, the calculation of the lower limit rotation speed is performed (the calculation indicated by the symbol "MAX" in the figure). The result of this calculation becomes the target rotation speed of the engine 20. For example, since the number of revolutions obtained by one calculation of the relaxation processing is 1.5 × E2rpm, and the lowest engine speed is not lower than the lowest engine speed when the lowest engine speed is E2rpm, the target number of revolutions of the engine 20, which is the result of the calculation indicated by the symbol "MAX", is 1.5 × E2 rpm.

Fig. 4 is a diagram showing a calculation flow of the target output of the engine 20 according to the embodiment. Referring to fig. 4, first, a basic output of engine 20 corresponding to the engine target rotation speed and the requested electric power is determined using the engine target output basic map.

Fig. 10 is a diagram showing an engine target output basic map according to the embodiment. Referring to fig. 10, in this map, the column header value is the target rotation speed, the row header value is the requested output (requested power, in other words, load applied to engine 20), and the cell value is the output of engine 20. When the requested power is not more than 2390rpm, the output of engine 20 is set to be constant (load is constant) as long as the rotation speed is the same even if the requested power is changed. At 2395rpm, if the requested power is 50kW or more, the output of engine 20 is set to be larger as the requested power is larger (priority is given to power generation). For example, when the target rotation speed of the engine 20 is 1840rpm and the requested power is 100kW, based on F4kW which is a cell value corresponding to 1600rpm of the column heading directly below 1840rpm and 100kW of the row heading and F5kW which is a cell value corresponding to 2000rpm of the column heading directly above 1840rpm and 100kW of the row heading, by interpolation, (1840-.

Returning to fig. 4, a correction coefficient corresponding to the engine target rotation speed and the SOC of the battery 10 is determined using the target output SOC correction coefficient map. This correction coefficient is a correction coefficient for increasing the output of engine 20 when the SOC decreases.

Fig. 11 is a diagram showing a target output SOC correction coefficient map according to this embodiment. Referring to fig. 11, in this map, the value of the column header is the SOC of engine 20, and the value of the cell is the correction coefficient. The SOC correction coefficient is set to G1 if the SOC is 50 or less, and the correction coefficient is set to G2 if the SOC is 60 or more. For example, when the SOC is 40%, the correction coefficient is G1.

Returning to fig. 4, an operation (an operation indicated by the symbol "x" in the drawing) is performed to multiply the output of engine 20 specified by the engine target output basic map of fig. 10 by the correction coefficient specified by the target output SOC correction coefficient map of fig. 11. For example, when the output of the engine 20 is J3kW and the correction coefficient is G1, J3 × G1kW is obtained.

Next, a relaxation coefficient corresponding to the engine speed and the SOC of battery 10 is determined using a relaxation coefficient map. The relaxation coefficient is a coefficient for relaxing a change in the output of the engine 20 when there is a margin in the SOC.

Fig. 12 is a diagram showing a relaxation coefficient map according to this embodiment. Referring to fig. 12, in this map, the value of the column header is SOC, and the value of the cell is relaxation coefficient. A relaxation coefficient is set such that the degree of relaxation increases as the SOC increases. If the SOC is set to 30 or less, H1 indicating that the relaxation coefficient is not relaxed at all is obtained. When the SOC is 40 or more, the relaxation coefficient is set to be constant even if the SOC changes. For example, when the SOC is 40%, H3 is determined as the relaxation coefficient.

Returning to fig. 4, the following operations are performed: the relaxation processing is performed on the output of the engine 20 obtained by the operation indicated by the symbol "x" using the relaxation coefficient specified by the relaxation coefficient map of fig. 12. Here, as the relaxation process, the relaxation process is performed once, but the relaxation process may be performed twice or more. In the first relaxation processing, for example, the following operation is performed: a value obtained by dividing a difference obtained by subtracting the output of the previous engine 20 from the output of the engine 20 obtained by the operation indicated by the symbol "x" described above by the relaxation coefficient is added to the output of the previous engine 20. As shown in fig. 2, the calculation of fig. 4 is executed for each predetermined control cycle, but the "previous time" refers to the time before the predetermined control cycle. For example, when the relaxation coefficient is H3 corresponding to SOC 40%, the output of engine 20 obtained by the calculation indicated by the symbol "x" is J4kW, and the previous rotation speed is J4 × 9/10kW, the relaxation processing is performed once to obtain (J4-J4 × 9/10)/H3+ J4 × 9/10/(1 +9 × H3) × J4/(10 × H3) kW. As described above, as the relaxation coefficient ratio H1 becomes larger, the change in the output from the previous engine 20 becomes smaller.

When the output power is lower than the minimum generated power after the calculation of the first relaxation process, a calculation is performed to limit the lower limit output of the engine 20 (a calculation indicated by a symbol "MAX" in the drawing). The minimum generated power is power obtained by subtracting the power that can be output from the battery 10 from the requested power. The result of this calculation becomes the target output of the engine 20. For example, since the output obtained by the calculation of the first relaxation process is J5+20kW, and the lowest generated power is not lower than the lowest generated power in the case of J5kW, the target output of the engine 20, which is the result of the calculation indicated by the symbol "MAX", is J5+20 kW.

Fig. 13 is a diagram showing example 1 of the control result of the embodiment. Referring to fig. 13, when vehicle 100 is driven in a steady operation of 40km/h from a state where the initial SOC of battery 10 is 50%, as shown in fig. 13 (a), the requested output for driving vehicle 100 becomes a constant value as shown by the broken line in fig. 13 (C). As shown in fig. 13 (B) to 13 (D), engine 20 is controlled so that the target rotation speed and the target output calculated according to the flow shown in fig. 3 and 4 are achieved from time 0 to 40 seconds when the SOC of battery 10 does not reach the end-of-charge SOC. At time 40 seconds or less, the SOC of battery 10 reaches the end-of-charge SOC, and therefore engine 20 is stopped. Note that, in fig. 13 (C) and 13 (D), graphs are drawn so that the rotation speed and the output increase sharply from time 0 second, but actually, the control is performed so that the increase in the rotation speed and the output is smoothed by the smoothing processing shown in fig. 3 and 4.

Fig. 14 is a diagram showing an example 2 of the control result of the embodiment. Referring to fig. 14, when vehicle 100 is driven in a steady operation of 100km/h from a state where the initial SOC of battery 10 is 50%, as shown in fig. 14 (a), the requested output for driving vehicle 100 becomes a constant value as shown by the broken line in fig. 14 (C). As shown in fig. 14 (B) to 14 (D), engine 20 is controlled so that the target rotation speed and the target output calculated according to the flow shown in fig. 3 and 4 are achieved from time 0 to 85 seconds when the SOC of battery 10 does not reach the end-of-charge SOC. At time 85 seconds or less, the SOC of battery 10 reaches the end-of-charge SOC, and therefore engine 20 is stopped. Note that, in fig. 14 (C) and 14 (D), graphs are drawn so that the rotation speed and the output increase sharply from time 0 second, but actually, control is performed so that the increase in the rotation speed and the output is smoothed by the smoothing processing shown in fig. 3 and 4.

Fig. 15 is a diagram showing example 3 of the control result of the embodiment. Referring to fig. 15, when vehicle 100 is driven in a steady operation of 100km/h from a state where the initial SOC of battery 10 is 20%, as shown in fig. 14 (a), the requested output for driving vehicle 100 becomes a constant value as shown by the broken line in fig. 15 (C). Further, as shown in fig. 15 (B) to 15 (D), since the charge completion SOC is not reached during the entire period shown in the drawing, the engine 20 is controlled so that the target rotation speed and the target output calculated according to the flow shown in fig. 3 and 4 are achieved during the entire period shown in the drawing. Until the time point of reaching SOC 40% is in the vicinity of 58 seconds, engine 20 is controlled based on the output of power generation priority indicated by the cell value of 50kW or more of the requested output of the line head of rotation speed 2395rpm indicated by the column head in fig. 10. When the SOC reaches 40% at around time 58 seconds, the correction coefficient is changed as shown in the target rotation speed SOC correction coefficient map of fig. 7, and therefore the target rotation speed and the target output of engine 20 are reduced. Note that, in fig. 15 (C) and 15 (D), graphs are drawn so that the rotation speed and the output increase sharply from time 0 second, but actually, the control is performed so that the increase in the rotation speed and the output is smoothed by the smoothing processing shown in fig. 3 and 4.

Fig. 16 is a diagram showing an example 1 of the overall control result of the embodiment. Fig. 16 shows an example of a case where the vehicle 100 is caused to travel so that the vehicle speed changes to achieve the mode travel (Real Driving Emission test) as shown in fig. 16 a. In this case, as shown in fig. 16 (B), the SOC can be controlled to be within a range from the charge start SOC to the charge end SOC.

As shown in fig. 16 (C) and 16 (D), the rotation speed and the output of the engine 20 can be set to 0 for a long period during low-load running from time 0 to 1800 seconds. In fig. 16 (C), the solid line indicates the output of engine 20, and the broken line indicates the output of MG31 for driving vehicle 100.

As shown in fig. 16 (C) and 16 (D), during high-load running from time 3900 seconds to 6400 seconds, power generation is performed in which the rate of change in the rotation speed and output of engine 20 is suppressed by the relaxation processing shown in fig. 3 and 4.

Fig. 17 is a diagram showing an example 2 of the overall control result of the embodiment. Referring to fig. 17, an example of a case where vehicle 100 is driven so that the vehicle speed changes from 0km/h to 140km/h at full-open acceleration as shown in fig. 17 (a) is shown. In this case, as shown in fig. 17 (B), the full-load running is performed from time 0 second to 25 seconds during acceleration, and therefore the SOC is greatly reduced.

As shown in fig. 17 (C) and 17 (D), MG31 for driving is operated at almost the highest output during acceleration from time 0 to 25 seconds. Accordingly, as shown in fig. 17 (B), the SOC of the battery 10 is rapidly reduced, and therefore the output and the rotation speed of the engine 20 are controlled so as to prioritize power generation without the relaxation process. Thereafter, as shown in fig. 17 (B), when the SOC of the battery 10 reaches the charge start SOC at around time 75 seconds, the output of the engine 20 decreases.

[ modified examples ]

(1) In the foregoing embodiments, the MG31 and the MG32 are both motor generators. However, not limited to this, MG31 may be a generator. MG32 may also be an electric motor.

(2) In the above-described embodiment, the engine 20 is controlled using the maps of fig. 5 to 12 predetermined so as to limit the rate of change in the target rotation speed and the rate of change in the target output torque of the engine 20, according to the flows of fig. 3 and 4. However, without being limited to this, if at least one of the rate of change of the target rotation speed of the engine 20 and the rate of change of the target output torque is limited, the control may be performed by another method. Further, at least one of the change rate of the target rotation speed and the change rate of the target output torque may be limited to 0 (that is, at least one of the target rotation speed and the target output torque may be made constant) without limiting at least one of the change rate of the target rotation speed and the change rate of the target output torque to be smaller than a predetermined change rate.

(3) In the foregoing embodiment, the structure of the exhaust gas treatment device is a combination of the DPF71 and the NSR catalyst 72. However, the configuration of the exhaust gas treatment device is not limited to this, and may be any configuration. For example, the DeNOx catalyst that reduces NOx contained in the exhaust gas may be an SCR catalyst that uses a reducing agent (e.g., urea water or HC) instead of the NSR catalyst 72.

(4) The foregoing embodiment can be regarded as a disclosure of a hybrid system including the engine 20, the MG31, the MG32, the battery 10, and the control devices (EG-ECU52, HV-ECU51, PCU 11). Further, it can be regarded as disclosure of such a control device of the hybrid system or disclosure of a control method of the hybrid system. The disclosure of the vehicle 100 including such a hybrid system can be regarded as being applicable.

[ Effect ]

(1) As shown in fig. 1, the hybrid system includes: an engine 20; MG32 that generates electric power using power output from engine 20; a battery 10 that charges generated power obtained by MG 32; an MG31 for driving vehicle 100, which is driven using at least one of the electric power discharged from battery 10 and the electric power generated by MG 32; and a control device (EG-ECU52, HV-ECU51, PCU 11). As shown in fig. 2 to 12, the control device controls to limit at least one of the rate of change of the target rotation speed and the rate of change of the target output torque of the engine 20.

Thus, in the hybrid system, at least one of the rate of change of the target rotation speed of the engine 20 and the rate of change of the target output torque is limited. As a result, the emission amount of black smoke and nitrogen oxides can be reduced.

(2) The calculation shown in the flow charts of fig. 3 and 4 is designed in advance to limit at least one of the rate of change of the target rotational speed of engine 20 and the rate of change of the target output torque to be smaller than at least one of the rate of change of the black smoke emission more than the normal limit value and the rate of change of the nitrogen oxide emission more than the normal limit value. The control device controls the engine 20 based on such calculation. Further, it may be an autonomous limit value instead of a legal limit value.

Thus, in the hybrid system, the engine 20 is controlled such that at least one of the rate of change in the target rotation speed and the rate of change in the target output torque of the engine 20 is relatively smaller than at least one of the rate of change in the target rotation speed and the rate of change in the target output torque of the engine 20, at which at least one of black smoke and nitrogen oxides discharged from the engine 20 is discharged more than the normal limit value.

(3) The control device controls at least one of the rate of change of the target rotational speed and the rate of change of the target output torque of the engine 20 using the control maps shown in fig. 5 to 12 used for the calculations shown in the flowcharts of fig. 3 and 4.

Thus, in the hybrid system, engine 20 is controlled such that at least one of the rate of change in the target rotational speed and the rate of change in the target output torque of engine 20 is relatively smaller than at least one of the rate of change in the target rotational speed and the rate of change in the target output torque of engine 20 at which at least one of black smoke and nitrogen oxides discharged from engine 20 is discharged more than the legal limit value.

(4) As shown in fig. 16 and 17, in the calculation shown in the flow charts of fig. 3 and 4, when the SOC of the battery 10 is higher than the charge start SOC, at least one of the rate of change in the target rotation speed of the engine 20 and the rate of change in the target output torque is relatively smaller than in the case where the SOC of the battery 10 is lower than the charge start SOC.

(5) The control maps shown in fig. 5 to 12 include: the engine speed basic map of fig. 5 capable of determining the rotation speed from the requested electric power to the MG32 and the vehicle speed; and the engine target output basic map of fig. 10 capable of determining the target output torque from the requested electric power to the MG32 and the target rotation speed.

(6) As shown in fig. 10, the engine target output basic map in the control map includes: a region in which the power generation ratio is prioritized over control for limiting at least one of the rate of change in the target rotational speed of the engine 20 and the rate of change in the target output torque. The priority of power generation is to issue the requested power by the output of the engine 20 without particularly limiting the rate of change of the target rotational speed and the rate of change of the target output torque.

Thus, when the SOC of the battery 10 is lower than the charge start SOC, suppression of at least one of the rate of change of the target rotation speed of the engine 20 and the rate of change of the target output torque can be prioritized.

The embodiments disclosed here are also intended to be implemented in appropriate combinations. Moreover, the presently disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present disclosure is defined by the claims rather than the description of the above embodiments, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Description of the reference numerals

A battery; PCU; an engine; 21. 22, 41. A gear; 31. MG; a drive wheel; a drive shaft; a power transfer gear; HV-ECU; an EG-ECU; 61. 62, 63, 64. 65.. an accelerator opening sensor; 66.. a vehicle speed sensor; 71... DPF; NSR catalyst; an exhaust gas temperature sensor; an a/F sensor 82.; a NOx sensor; a vehicle.

Claims

1. A hybrid system is characterized by comprising:

an internal combustion engine;

a generator that generates electric power using power output from the internal combustion engine;

an electric storage device that charges the generated electric power obtained by the generator;

a vehicle-driving electric motor that is driven using at least one of electric power discharged from the electric storage device and electric power generated by the generator; and

and a control device that controls to limit at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.

2. The hybrid system according to claim 1,

the control device restricts at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine to be smaller than at least one of a rate of change of black smoke emission more than a1 st prescribed amount and a rate of change of nitrogen oxide emission more than a2 nd prescribed amount.

3. The hybrid system according to claim 2,

the control device controls at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine using a predetermined control map.

4. The hybrid system according to claim 2 or 3,

the control device controls at least one of a rate of change in the target rotation speed and a rate of change in the target output torque of the internal combustion engine to be relatively smaller when the SOC of the power storage device is higher than a predetermined value than when the SOC of the power storage device is lower than the predetermined value.

5. The hybrid system according to claim 3,

the control mapping includes: a map of the rotational speed can be determined from the requested power to the generator and the vehicle speed; and a map capable of determining a target output torque from the requested electric power to the generator and a target rotation speed.

6. The hybrid system according to claim 3,

the control map includes a region that gives priority to control of limiting at least one of a rate of change in the target rotation speed and a rate of change in the target output torque of the internal combustion engine in terms of power generation ratio.

7. A control device for a hybrid system, which controls the hybrid system, is provided with: an internal combustion engine; a generator that generates electric power using power output from the internal combustion engine; an electric storage device that charges the generated electric power obtained by the generator; and a motor for driving the vehicle, which is driven by using at least one of the electric power discharged from the power storage device and the electric power generated by the generator,

the control apparatus of the hybrid system is characterized in that,

control is performed to restrict at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.

8. A control method for a hybrid system, which is a control method for a control device for controlling a hybrid system, the hybrid system comprising: an internal combustion engine; a generator that generates electric power using power output from the internal combustion engine; an electric storage device that charges the generated electric power obtained by the generator; and a motor for driving the vehicle, which is driven by using at least one of electric power discharged from the power storage device and electric power generated by the generator,

the control method of the hybrid system is characterized in that,

the method comprises the following steps: the control device controls to restrict at least one of a rate of change of a target rotation speed and a rate of change of a target output torque of the internal combustion engine.