JP6459583B2 - Control method of hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle control method, and more particularly, to a hybrid vehicle control method capable of reliably performing PM regeneration while improving fuel efficiency.

  In recent years, from the viewpoint of improving fuel efficiency and environmental measures, part of the driving force generated by the engine is replaced by a motor-driven generator that uses a battery as a power source, and surplus energy during normal driving and regenerative energy during braking are collected. Hybrid vehicles that store electricity as electric power in batteries are attracting attention.

  When a diesel engine is used for the engine of this hybrid vehicle, an exhaust gas purification system for removing harmful substances such as particulate matter (PM) and nitrogen oxide (NOx) contained in the exhaust gas is required. As for the former PM, a PM collection filter for collecting PM by a ceramic honeycomb porous filter is mainly used. For the latter NOx, a reducing agent catalyst system, a NOx occlusion reduction catalyst, and the like have been put into practical use.

  The above PM collection filter collects and purifies PM in exhaust gas with a filter. In order to prevent clogging of the filter, it is necessary to burn and remove PM before reaching the collection limit. (For example, refer to Patent Document 1).

  When the temperature of the exhaust gas is high, PM spontaneously burns continuously. However, when the temperature of the exhaust gas is low, the unburned fuel is temporarily supplied into the exhaust gas, and the hydrocarbon (HC) of the unburned fuel is oxidized by the oxidation catalyst (DOC) arranged in the front stage of the filter, Using the heat of oxidation reaction, the DOC is heated to 500 ° C. or higher to raise the temperature of the exhaust gas, and PM regeneration for forcibly burning the PM deposited on the filter is required.

  When performing this PM regeneration, the temperature of the exhaust gas is raised to a temperature at which the unburned fuel is activated (for example, about 200 ° C. or higher) in the preceding DOC catalyst, regardless of the torque required by the engine. It was necessary to perform an operation for raising the exhaust gas temperature itself by supplying The fuel supplied to raise the temperature of the exhaust gas does not contribute to the driving force required for the running of the hybrid vehicle. Therefore, the reliability of PM regeneration is improved and the fuel consumption of the hybrid vehicle is deteriorated. The problem is in a trade-off relationship.

JP 2005-16317 A

  An object of the present invention is to provide a control method for a hybrid vehicle that can reliably perform PM regeneration while improving fuel efficiency as compared with the prior art.

A control method for a hybrid vehicle of the present invention that achieves the above-described object includes a motor generator connected to a battery, a hybrid system capable of connecting and disconnecting an engine and a drive shaft, and an exhaust passage through which exhaust gas from the engine flows. A control method for a hybrid vehicle comprising: a PM collection filter provided; and an exhaust gas purification system having a fuel supply means for supplying fuel to a location upstream of the PM collection filter in the exhaust passage , When the PM collection filter enters a regeneration waiting state while the hybrid vehicle is running, the motor generator is rotated with the power supplied from the battery with the motor generator and the drive shaft in contact with each other. while starting the starts to the said engine and said drive shaft in the disconnection state, the charge rate of the battery is pre When the set lower limit value is reached, the fuel supply means is activated to start regeneration of the PM collection filter, while the engine and the drive shaft are brought into contact with each other, and the engine of the engine A required travel torque is determined from the rotational speed and the vehicle speed of the hybrid vehicle and preset first map data, and a required regeneration torque determined from the requested travel torque and preset second map data. The motor generator is regeneratively generated to charge the battery.

  According to the method for controlling a hybrid vehicle of the present invention, a load is applied to the diesel engine not only by the torque necessary for traveling of the hybrid vehicle but also by regenerative power generation of the motor generator, so that the load fluctuation is stabilized and flows into the oxidation catalyst. An opportunity to reliably increase the temperature of the exhaust gas can be obtained. In addition, due to the temperature rise of the exhaust gas, the amount of fuel used to raise the temperature of the exhaust gas during PM regeneration can be reduced, and a part of the load applied to the diesel engine can be reduced by regenerative power generation of the motor generator. Can be recovered and charged to the battery. Therefore, in the hybrid vehicle, the PM collection filter can be reliably regenerated while improving the fuel efficiency as compared with the conventional vehicle.

It is a block diagram which shows the example of a hybrid vehicle. It is a flowchart explaining the control method of the hybrid vehicle which consists of the 1st Embodiment of this invention. It is a graph which shows the example of the map data which concerns on determination of request | requirement regenerative torque. It is a flowchart explaining the control method of the hybrid vehicle which consists of the 2nd Embodiment of this invention. It is a flowchart explaining the control method of the hybrid vehicle which consists of the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration example of a hybrid vehicle.

  This hybrid vehicle (hereinafter referred to as “HEV”) 1 includes a diesel engine 4 and a motor generator 5 via a transmission 6 on a drive shaft 3 that transmits driving force to a pair of left and right drive wheels 2 and 2, respectively. A hybrid system 7 that can be connected and disconnected and an exhaust gas purification system 9 provided in an exhaust passage 8 of the diesel engine 4 are provided.

  The hybrid system 7 includes a battery 11 that is electrically connected to the motor generator 5 through an inverter 10, and a motor clutch 12 that is interposed between the transmission 6 and the motor generator 5. Further, the battery 11 is provided with an SOC sensor 13 for measuring a storage rate (SOC). The hybrid system 7 is controlled by the HCU 14.

  The exhaust gas purification system 9 has a large-diameter catalytic converter 15 interposed in the exhaust passage 8 and an injection nozzle 16 which is a fuel supply means installed in the exhaust passage 8 upstream of the catalytic converter 15. Yes. In the catalytic converter 15, a PM collection filter 18 in which an oxidation catalyst (DOC) 17 is disposed in the previous stage is stored. As fuel supply means, post injection in fuel injection into the cylinder 19 of the diesel engine 4 can be used instead of the injection nozzle 16.

  The DOC 17 is formed by supporting rhodium, cerium oxide, platinum, aluminum oxide or the like on a metal carrier molded into a structure having a function of mixing the exhaust gas G of the diesel engine 4. The PM collection filter 18 is formed of a monolith honeycomb wall flow type filter in which the inlets and outlets of a porous ceramic honeycomb channel (cell) are alternately plugged.

  In the configuration example of FIG. 1, the DOC 17 and the PM collection filter 18 are separated from each other. However, the DOC 17 and the PM collection filter 18 may be integrally used as a CSF in which an oxidation catalyst substance is supported on the filter.

  An inlet pressure sensor 20 and an outlet pressure sensor 21 are installed in the vicinity of the inlet and the outlet of the catalytic converter 15, respectively. These inlet pressure sensor 20 and outlet pressure sensor 21 are intended to confirm the timing of regeneration of the PM collection filter 18 by obtaining the differential pressure of the exhaust gas G in the catalytic converter 15.

  In the engine body 22 of the diesel engine 4, the intake air supplied into each of the plurality of cylinders 19 when the intake valve 23 is opened is mixed and burned with the fuel injected from the injector 24, and is stored in the cylinder 25. After the piston 26 is reciprocated and the crankshaft 27 is rotationally driven, when the exhaust valve 28 is opened, it becomes exhaust gas G and is exhausted from the exhaust manifold 29 to the exhaust passage 8. The exhaust gas G passes through an exhaust throttle valve 30 provided in the exhaust passage 8, and is then purified by the exhaust gas purification system 9 described above and released to the outside. The exhaust throttle valve 30 may be provided on the downstream side of the catalytic converter 15. The rotational power of the crankshaft 27 is transmitted from the transmission 6 to the drive shaft 3 via the fluid coupling 31 and the wet multi-plate clutch 32.

  Each part of the engine main body 22 and the exhaust gas purification system 9 are controlled by an ECU 33 connected to the HCU 14 through an in-vehicle network (indicated by a one-dot chain line). The ECU 33 is connected to a rotation sensor 34 that measures the engine speed of the diesel engine 4, a vehicle speed sensor 35 that measures the vehicle speed of the HEV 1, and an accelerator opening sensor 36 that detects the opening of the accelerator.

  A hybrid vehicle control method (hereinafter simply referred to as “control method”) according to the first embodiment of the present invention in the HEV 1 will be described below as control contents of the ECU 33 and the HCU 14 with reference to FIG. .

  When there is a regeneration request for PM collection while the HEV 1 is traveling (S10), the ECU 33 determines that the PM collection filter 18 is in a regeneration waiting state (S12), and the HCU 14 To communicate. Examples of the regeneration request for PM collection include a case where the differential pressure value of the catalytic converter 15 calculated from the measured values of the inlet sensor 20 and the outlet sensor 21 exceeds a preset threshold value. The

  Receiving this transmission, the HCU 14 puts the motor clutch 12 into the engaged state (S14), rotationally drives the motor generator 5 by the power supply from the battery 11 through the inverter 10, and puts the wet multi-plate clutch 32 in the disengaged state. (S16). Thereby, HEV1 will be in the state which drive | works only with the driving force of the motor generator 5. FIG. Next, the detected value V of the SOC sensor 13 is compared with a preset lower limit value X (S18). When the detected value V becomes equal to the lower limit value X, it is determined that the battery 11 has been discharged. (S20), to that effect is transmitted to the ECU 33. As the lower limit value X, it is desirable to use a value in which the SOC exceeds 0% and is in a range of 40% or less which is the lower limit of the normal use range of the battery 11.

  Receiving this transmission, the ECU 33 injects fuel from the injection nozzle 16 (S22) and starts regeneration of the PM collection filter 18. On the other hand, the wet multi-plate clutch 32 is brought into a contact state (S24). Thereby, HEV1 will be in the state which drive | works with the driving force of the diesel engine 4 mainly. Next, the measured value of the rotation sensor 34 and the measured value of the vehicle speed sensor 35 are input (S26), and the required travel required for the travel of the HEV 1 based on the measured values and the first map data set in advance. The torque is determined (S28) and transmitted to the HCU 14. As this 1st map data, what is called a torque curve set for every diesel engine 4 is illustrated.

  The HCU 14 determines the required regenerative torque based on the transmitted required travel torque and preset second map data (S30), and performs regenerative power generation of the motor generator 5 at the required regenerative torque. The battery 11 is charged through the inverter 10 (S32).

  FIG. 3 shows an example of the second map data. This map data is obtained in advance by experiments and calculations for the relationship between the engine speed of the diesel engine 4 and the torque for setting the temperature of the exhaust gas G in the vicinity of the inlet of the catalytic converter 15 to a preset value. is there. In this map data, when the required running torque H is obtained, the required regenerative torque D for obtaining the temperature T (for example, about 200 ° C. or more) of the exhaust gas G in the vicinity of the inlet of the catalytic converter 15 and the optimum fuel efficiency is determined by the engine rotation. This is the difference between the required travel torque H in the number K and the map data. The determination of the required travel torque, the determination of the required regenerative torque, and the charging of the battery 11 by regenerative power generation are repeatedly performed according to the change in the travel state of the HEV 1 (S26 to S32).

  By performing the control as described above, a load is applied to the diesel engine 4 by regenerative power generation of the motor generator 5 in addition to the required travel torque, so that the temperature of the exhaust gas G flowing into the DOC 17 can be reliably increased. . Further, since the temperature of the exhaust gas G rises, the amount of fuel injection from the injection nozzles 16 other than the power purpose required for the temperature increase is reduced as compared with the prior art, and the diesel engine is being regenerated during the regeneration of the PM collection filter 18. A part of the load applied to 4 can be recovered as electric energy by regenerative power generation of the motor generator 5 to charge the battery 11.

  For this reason, in the HEV 1, the PM trapping filter can be reliably regenerated while improving the fuel efficiency as compared with the prior art.

  The control method which consists of the 2nd Embodiment of this invention is demonstrated below based on FIG. In FIG. 4, the same control numbers as in FIG. 2 are assigned the same step numbers, and the description thereof is omitted.

  In the control method according to the first embodiment described above, the SOC of the battery 11 is set in advance for charging the battery 11 by regenerative power generation of the motor generator 5 (S32) from the viewpoint of preventing the deterioration of the battery 11. It is necessary to stop when the upper limit is reached. The upper limit value is preferably the rated maximum capacity of the battery 11. The rated maximum capacity is a value defined in advance according to the manufacturing specifications of the battery 11, and is normally a state in which the SOC of the battery 11 is 70 to 90%.

  However, if the charging of the battery 11 is stopped in step 32, the control by the ECU 33 and the HCU 14 is terminated, and there is a possibility that the regeneration of the PM collection filter 18 is interrupted in an insufficient state.

  Therefore, in order to continue the regeneration of the PM collection filter 18 even after the SOC of the battery 11 reaches a preset upper limit value, in addition to the control method according to the first embodiment, the following control method is used. carry out.

  After charging the battery 11 (S32), the HCU 14 compares the detection value V of the SOC sensor 13 with a preset upper limit value Y (S34). When the detected value V becomes equal to the upper limit value Y, it is determined that the charging of the battery 11 has been completed (S36), and the motor generator 5 is driven to rotate by power feeding from the battery 11 through the inverter 10. The wet multi-plate clutch 32 is disengaged (S38), and the fact is transmitted to the ECU 33.

  Receiving this transmission, the ECU 33 adjusts the fuel injection amount of the injector 24 to set the engine speed of the diesel engine 4 to a preset value, and closes the exhaust throttle valve 30 (S40). As a preset value related to the engine speed, the idle speed when the vehicle is stopped is set so that torque fluctuation is less likely to occur when the wet multi-plate clutch 32 is reconnected when the HEV 1 is suddenly accelerated. A higher value is preferable.

  By performing the control as described above, the HEV 1 performs the motor traveling by the motor generator 5 while maintaining the idle operation state of the diesel engine 4 during the traveling after the battery 11 is charged to the upper limit value Y, Since the exhaust pressure is increased by closing the exhaust throttle valve 30 and a load is newly applied to the diesel engine 4, a decrease in the temperature of the exhaust gas G can be suppressed and the regeneration of the PM collection filter 18 can be continued. It is.

  The control method which consists of the 3rd Embodiment of this invention is demonstrated below based on FIG. In FIG. 5, the same control number as in FIG. 2 is assigned the same step number, and the description thereof is omitted.

  In the control method according to the first embodiment described above, the exhaust gas G that flows into the DOC 17 when the driver turns off the accelerator and the HEV 1 enters the inertial running state during regeneration of the PM collection filter 18 (S22 to S32). Therefore, there is a possibility that the regeneration of the PM collection filter 18 is interrupted in an insufficient state.

  Therefore, in addition to the control method according to the first embodiment, in order to continue the regeneration of the PM collection filter 18 even after the HEV 1 enters the inertial running state during the regeneration of the PM collection filter 18, Implement the control method.

  In parallel with the determination of the required travel torque, the determination of the required regenerative torque, and the charging of the battery 11 by regenerative power generation according to the change in the travel state of the HEV 1 (S26 to S32), the ECU 33 detects the accelerator opening sensor. It is determined from the detected value of 36 whether or not the accelerator is off (S42).

  When the accelerator is off, it is determined that the HEV 1 is in an inertial running state due to deceleration or downhill (S44), and that fact is transmitted to the HCU 14. Then, the wet multi-plate clutch 32 is disengaged (S46), the fuel injection amount of the injector 24 is adjusted to set the engine speed of the diesel engine 4 to a preset value, and the exhaust throttle valve 30 is closed. (S48). The preset value related to the engine speed is the same as that in step 40 in the control method according to the second embodiment described above.

  The HCU 14 that has received the above transmission performs regenerative power generation of the motor generator 5 at the maximum required regenerative torque Dmax in parallel and charges the battery 11 through the inverter 10 (S50). The maximum required regenerative torque Dmax corresponds to the case where the required travel torque H is zero in the second map data shown in FIG.

  By performing the control as described above, the HEV 1 is exhausted by closing the exhaust throttle valve 30 while maintaining the idle operation state of the diesel engine 4 during the travel after the HEV 1 is in an inertia traveling state due to a downhill or the like. Since the pressure is increased and a load is newly applied to the diesel engine 4, the regeneration of the PM collection filter can be continued while suppressing the decrease in the temperature of the exhaust gas G, and the regenerative power generation can also be continued. is there.

1 HEV
3 Drive shaft 4 Diesel engine 5 Motor generator 7 Hybrid system 8 Exhaust passage 9 Exhaust gas purification system 11 Battery 12 Motor clutch 13 SOC sensor 14 HCU
17 DOC
18 PM collection filter 32 Wet multi-plate clutch 33 ECU
34 Rotation sensor 35 Vehicle speed sensor 36 Accelerator opening sensor

Claims (5)

A motor-driven generator connected to a battery and a hybrid system capable of connecting and disconnecting an engine and a drive shaft, a PM collection filter interposed in an exhaust passage through which exhaust gas from the engine flows, and the PM collection in the exhaust passage A control method for a hybrid vehicle comprising an exhaust gas purification system having a fuel supply means for supplying fuel to a location upstream of a filter ,
When the PM collection filter is in a regeneration waiting state while the hybrid vehicle is running, the motor generator is rotated with power supplied from the battery while the motor generator and the drive shaft are in contact with each other. while starting the thereby starts to the said engine and said drive shaft in the disconnection state,
When the storage rate of the battery reaches a preset lower limit value, while starting the fuel supply means and starting regeneration of the PM collection filter,
The engine and the drive shaft are brought into contact with each other, and the required travel torque is determined from the engine speed of the engine and the vehicle speed of the hybrid vehicle and preset first map data,
A control method for a hybrid vehicle, wherein the motor generator is regeneratively generated with a required regenerative torque determined from the required running torque and preset second map data to charge the battery. An exhaust throttle valve interposed in the exhaust passage,
After the battery is charged, when the storage rate of the battery reaches a preset upper limit, the motor generator and the drive shaft are in contact with each other and the motor generator is supplied with power from the battery. Rotate and drive
The hybrid vehicle control method according to claim 1, wherein the engine and the drive shaft are disconnected, the engine speed of the engine is set to a preset value, and the exhaust throttle valve is closed.   The hybrid vehicle control method according to claim 2, wherein the preset upper limit value is a rated maximum capacity of the battery. An exhaust throttle valve interposed in the exhaust passage,
When the hybrid vehicle enters an inertial running state after charging the battery, the motor generator is regeneratively generated with the maximum required regenerative torque to charge the battery, and the engine and the drive shaft are disconnected. 2. The method for controlling a hybrid vehicle according to claim 1, wherein the engine speed of the engine is set to a preset value and the exhaust throttle valve is closed.   The hybrid vehicle control method according to any one of claims 1 to 4, wherein the preset lower limit value is a value in a range of more than 0 and 40% or less.

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