JP2011194926A - Vehicle and control method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To materialize both purification of exhaust emissions and improvement of vehicle fuel economy.SOLUTION: In a hybrid vehicle 1 including an engine 2 and a motor generator 3 as power sources and including an exhaust emission control device 16 purifying exhaust emission by catalysis, when an exhaust emission temperature calculated in step 100 is higher than a catalyst active temperature, the hybrid vehicle 1 transfers to a normal travel mode by the engine 2 (step 101). When the exhaust emission temperature calculated in the step 100 is lower than the catalyst active temperature and when it is in a charging state that a travel by the motor generator 3 is impossible in step 102, the hybrid vehicle 1 transfers to a travel power generation mode wherein the hybrid vehicle 1 travels while charged by the motor generator 3 (step 103). When it is in a charging state that the travel by the motor generator 3 is possible in the step 102, the hybrid vehicle 1 transfers to an electric travel mode by the motor generator 3 (step 104).

Description

  The present invention relates to a vehicle and a control method therefor, and more specifically, in a hybrid vehicle equipped with an internal combustion engine and a motor generator as a power source, and a vehicle capable of achieving both purification of exhaust gas and improvement in fuel consumption, and It relates to the control method.

  In recent years, in order to improve vehicle fuel efficiency and the like, development of hybrid vehicles combining an internal combustion engine and a motor generator has been promoted. As an example of this hybrid vehicle, there is one that warms up the engine by increasing the power generation load and raises the exhaust gas temperature to purify the exhaust gas (see, for example, Patent Document 1).

  By the way, when the internal combustion engine is a gasoline engine, the exhaust gas regulation can be achieved relatively easily by using a three-way catalyst or the like. It is essential to purify exhaust gas using treatment technology.

  This exhaust gas aftertreatment technology is a technology that purifies exhaust gas that could not be purified by the engine body immediately before exhaust, and specifically uses a filter to collect and burn particulate matter (PM). There is a configuration in which nitrogen oxide (NOx) or the like is reduced by utilizing a chemical change caused by DPF (Diesel Particulate Filter) or a catalyst.

  Here, FIG. 6 shows the temperature dependence of the NOx purification rate of the NOx purification catalyst. However, in the NOx purification catalyst, NOx can hardly be purified in an operating state where the exhaust gas temperature is 200 ° C. or lower. When this NOx purification catalyst is used, it is necessary to keep the exhaust gas temperature at a high temperature in order to improve the NOx purification rate. For this reason, the combustion heat of the fuel is used. This is not only the case for the NOx purification catalyst, but also the same thing is done during regeneration of the DPF for PM purification, and there is a problem that the fuel consumption of the vehicle is lowered.

  For this reason, in a hybrid vehicle equipped with a diesel engine and a motor generator, the fuel efficiency may be reduced due to exhaust gas purification, despite the adoption of the motor generator to improve the fuel efficiency. An important issue is how to efficiently purify the exhaust gas of a diesel engine to achieve both purification of the exhaust gas and improvement of fuel consumption.

JP 2008-179262 A

  An object of the present invention is to provide a vehicle capable of achieving both purification of exhaust gas and improvement in vehicle fuel efficiency in a hybrid vehicle equipped with an internal combustion engine and a motor generator, and a control method therefor.

  A vehicle of the present invention for achieving the above object includes an internal combustion engine and a motor generator as power sources, and includes an exhaust gas purification device that purifies exhaust gas generated by operation of the internal combustion engine by a catalytic action, In a vehicle including a power storage device capable of charging the electric power of the motor generator, a setting in which the temperature of the exhaust gas is set in advance in relation to the activation temperature of the catalyst of the exhaust gas purification device when the internal combustion engine is operated. When the temperature is higher than the temperature, the vehicle is driven by the internal combustion engine, and when the temperature of the exhaust gas is lower than the set temperature, the charge state of the power storage device is monitored to preset the charge state. If it is determined that the motor generator is in a chargeable state with reference to the first set charge value, the motor generator is driven to perform the first setting. A control unit that performs control to generate power while operating the internal combustion engine and to charge the power storage device when it is determined that the motor generator cannot be traveled on the basis of a power value; It is a vehicle.

  Further, in the vehicle described above, the control unit monitors a state of charge of the power storage device during traveling by the motor generator, and the state of charge is preset at a value lower than the first set charge value. If it is determined that the motor generator is in a chargeable state based on the second set charge value, the motor generator continues to run, and the motor power generation is performed based on the second set charge value. When it is determined that the vehicle is in a charging state where traveling by the machine is impossible, control is performed to generate power while operating the internal combustion engine and charge the power storage device.

  In addition, the vehicle control method of the present invention for achieving the above object includes an internal combustion engine and a motor generator as power sources, and exhaust gas purification that purifies exhaust gas generated by operation of the internal combustion engine by catalytic action. When the internal combustion engine is operated in a vehicle control method comprising a power storage device capable of charging the electric power of the motor generator, the exhaust gas temperature becomes the activation temperature of the catalyst of the exhaust gas purification device. When the temperature is higher than a preset temperature, the internal combustion engine travels. When the temperature of the exhaust gas is lower than the preset temperature, the charge state of the power storage device is monitored. When it is determined that the charging state is a charging state in which the motor generator can travel based on a preset first set charging value, the motor generator If it is determined that the vehicle is running and is in a charging state where running by the motor generator is not possible based on the first set charge value, the power storage device is charged by generating electricity while operating the internal combustion engine. This is a vehicle control method.

  In the vehicle control method described above, the state of charge of the power storage device is monitored during traveling by the motor generator, and the state of charge is preset at a value lower than the first set charge value. When it is determined that the motor generator is in a chargeable state based on the two set charge values, the motor generator continues to run, and the motor generator uses the second set charge value as a reference. When it is determined that the vehicle is in a charging state where traveling is impossible, the power storage device is charged by generating power while operating the internal combustion engine.

  According to the vehicle and its control method of the present invention, when the temperature of the exhaust gas of the internal combustion engine is equal to or higher than the activation temperature of the catalyst of the exhaust gas purification device, such as during high-load running, the temperature is higher than the activation temperature of the catalyst. Since the exhaust gas flows to the exhaust gas purification device, the exhaust gas can be purified efficiently.

  Also, when the engine is in a charged state where running by the motor generator is impossible when the temperature of the exhaust gas of the internal combustion engine is lower than the activation temperature of the catalyst of the exhaust gas purification device, such as during low-load running, the internal combustion engine Since the load of the internal combustion engine is increased by generating and charging the motor generator while operating the engine, the temperature of the exhaust gas increases. As a result, exhaust gas having a temperature higher than the activation temperature of the catalyst flows to the exhaust gas purification device, so that the exhaust gas can be efficiently purified. In addition, this makes it possible to eliminate low-load operation with poor engine efficiency, thereby improving engine efficiency.

  Further, when the temperature of the exhaust gas of the internal combustion engine is lower than the activation temperature of the catalyst of the exhaust gas purification device, in the charged state where traveling by the motor generator is possible, the operation of the internal combustion engine is stopped and the power storage device By supplying power from the vehicle and shifting to running by a motor generator, it is possible to avoid the operation of the internal combustion engine having poor exhaust gas purification efficiency when the exhaust gas temperature is low.

  Therefore, in a vehicle including an internal combustion engine and a motor generator as a power source and an exhaust gas purification device that purifies exhaust gas by catalytic action, the exhaust gas efficiency is maintained by keeping the exhaust gas temperature and the catalyst temperature high. It is possible to purify well and to make the operating state of the internal combustion engine a high load operation with high engine efficiency. For this reason, it is possible to achieve both efficient purification of exhaust gas and improvement of fuel consumption.

It is a principal part block diagram of the vehicle of embodiment of this invention. It is a figure which shows an example of the temperature map of the exhaust gas at the time of driving | running | working with an engine. It is a figure which shows an example of the control flow of a vehicle. It is a figure which shows an example of the charging condition monitoring flow of FIG. It is a figure which shows the engine operation mode at the time of driving | running | working of a vehicle, a charging condition, exhaust gas temperature, and vehicle speed in time series. It is a figure which shows the temperature dependence of the NOx purification rate of a NOx purification catalyst.

  Hereinafter, a vehicle and a control method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a main configuration of a diesel hybrid vehicle (hereinafter simply referred to as a hybrid vehicle) 1 that is a vehicle of the present embodiment.

  The hybrid vehicle 1 has a diesel engine (an internal combustion engine, hereinafter simply referred to as an engine) 2 and a motor generator 3 as power sources, and can be charged with electric power generated by driving the motor generator 3. A battery (power storage device) 4 is provided.

  The driving force of the engine 2 is transmitted to driving wheels (rear wheels) 10 through the clutch 5, the transmission 6, the shaft 7, the differential gear 8, and the axle 9. Further, a part of the driving force of the engine 2 is taken out by a PTO (Power Take Off) unit 11 and transmitted to the motor generator 3 through the shaft 12. At this time, the electric power (alternating current) generated by driving the motor generator 3 is converted into direct current via the inverter 13 and can be charged in the battery 4.

  Further, when the engine 2 is stopped, the driving force of the motor generator 3 driven by the power supply from the battery 4 is transmitted to the transmission 6 via the shaft 12 and the PTO unit 11, and further, the shaft 7, the differential gear 8, It is transmitted to the drive wheel 10 through the axle 9.

  The electric system of each part such as the engine 2, the motor generator 3, the battery 4, the clutch 5, the transmission 6, the PTO unit 11, and the inverter 13 is an electronic control unit (Engine Control Unit; hereinafter abbreviated as ECU, control unit) 14. Controlled by In addition to the accelerator signal, shift signal, brake signal, and speed signal, information indicating the temperature of the exhaust gas is sent to the ECU 14. The broken lines indicate signal lines, and the arrows indicate the flow of electrical signals.

  Further, an exhaust gas purification device 16 is installed in the middle of the exhaust pipe 15 connected to the exhaust port of the engine 2. This exhaust gas purification device 16 is a device that purifies exhaust gas that could not be purified by the engine 2 immediately before discharge, for example, DPF (Diesel Particulate Filter) that collects and removes particulate matter (PM). And a catalyst part for purifying NOx. Reference numeral 17 denotes an intake pipe connected to the intake port of the engine 2.

  Next, FIG. 2 shows an example of an exhaust gas temperature map during travel by the engine 2 of the hybrid vehicle 1 of the present embodiment. Here, when the vehicle travels in a low load state as indicated by point A, the exhaust gas temperature is below 200 ° C., and therefore NOx reduction by the NOx purification catalyst cannot be expected.

  Therefore, in the hybrid vehicle 1 of the present embodiment, control is performed as follows. This will be described with reference to the control flow of FIG.

  First, in the hybrid vehicle 1 of the present embodiment, it is determined whether or not the exhaust gas temperature region is the active region of the NOx purification catalyst (step 100). Note that this exhaust gas temperature is not the actual exhaust gas temperature of the hybrid vehicle 1, but is calculated according to various situations by the calculation formula for calculating the exhaust gas temperature when the vehicle of the present embodiment is not controlled. Virtual exhaust gas temperature (hereinafter also referred to as calculated exhaust gas temperature).

  When it is determined in step 100 that the exhaust gas temperature region is the active region of the NOx purification catalyst (for example, during high load traveling), the routine proceeds to a normal traveling mode in which the engine 2 is driven (step 101). In this normal travel mode, exhaust gas having a temperature higher than the activation temperature of the NOx purification catalyst flows into the exhaust gas purification device 16. For this reason, since the NOx in the exhaust gas can be purified with the NOx purification rate of the NOx purification catalyst being high, the exhaust gas can be purified efficiently. Therefore, the amount of NOx emission can be reduced.

  Further, when it is determined in step 100 that the exhaust gas temperature region is not the active region of the NOx purification catalyst (for example, during low-load running), the state of charge (SOC) of the battery 4 is monitored and electric It is determined whether or not the battery is in a chargeable state where the generator 3 can travel (step 102).

  If it is determined in step 102 that the charge value of the battery 4 at that time is equal to or greater than the upper limit threshold value (first set charge value) and is in a charge state in which electric running is possible, the engine 2 is stopped (running) The power generation is stopped), and the mode is shifted to the electric travel mode in which the motor generator 3 is driven by the power supply from the battery 4 (step 103).

  In this electric travel mode, since the engine 2 is stopped, PM and NOx are not discharged. Further, it is possible to avoid the operation of the internal combustion engine having poor exhaust gas purification efficiency when the exhaust gas temperature is low.

  On the other hand, when it is determined in step 102 that the charge value of the battery 4 at that time is lower than the upper limit threshold value (first set charge value) and the electric running is impossible, the engine 2 is driven, The motor generator 3 is driven using a part of the driving force to shift to the traveling power generation mode for generating power (step 104).

  That is, when the exhaust gas temperature is low, the battery 4 is charged with the electric power generated by the motor generator 3 (the difference output between the points B and A in FIG. 2) by operating in the traveling power generation mode. This power generation increases the engine load and raises the exhaust gas temperature. In FIG. 2, the actual exhaust gas temperature is from 200 ° C. at point A to 400 ° C. at point B.

  Thereby, in the traveling power generation mode, the exhaust gas having a temperature higher than the activation temperature of the NOx purification catalyst flows into the exhaust gas purification device 16. For this reason, since the NOx in the exhaust gas can be purified with the NOx purification rate of the NOx purification catalyst being high, the exhaust gas can be purified efficiently. Therefore, the amount of NOx emission can be reduced. In addition, this makes it possible to eliminate low-load operation with poor engine efficiency, thereby improving engine efficiency.

  Next, the charging status (SOC) monitoring logic of the battery 4 will be described with reference to FIG. When it is determined in step 100 of FIG. 3 that the exhaust gas temperature region is not the active region of the NOx purification catalyst, as shown in FIG. 4, the charged value of the battery 4 at that time is the upper threshold (first set charge). Value) or more (step 102A).

  In step 102A, when the charged value of the battery 4 at that time is equal to or greater than the upper limit threshold value, it is determined that the electric running is possible and the electric driving mode is entered (step 103). On the other hand, if the charged value of the battery 4 at that time is lower than the upper limit threshold value in step 102A, it is determined that electric traveling is impossible and the mode is shifted to the traveling power generation mode (step 104).

  Even during the electric running after the transition to the electric running mode in step 103, the charging state of the battery 4 is monitored, and the charge value of the battery 4 at that time is a lower threshold set in advance at a value lower than the upper threshold. It is determined whether or not (second set charge value) or less (step 102B), and if it is higher than the lower limit threshold, it is determined that electric travel is possible, and the electric travel mode is continued. On the other hand, if the charged value of the battery 4 at that time is equal to or lower than the lower limit threshold value in step 102B, it is determined that the electric running is impossible and the mode is shifted to the running power generation mode (step 104). After the transition to the traveling power generation mode in step 104, the process returns to step 102A and the same control as described above is performed.

  Next, FIG. 5 shows the engine operation mode, the charging state, the exhaust gas temperature, and the vehicle speed during travel of the hybrid vehicle 1 of the present embodiment in time series. In addition, the same hatching was attached | subjected to the same operation mode in the time series of vehicle speed. Times t0 to t1, t4 to t5, t10 to t11, and t16 to t17 indicate idle stop periods, and times t1 to t2 indicate idle periods. In the time series of exhaust gas temperature, the solid line indicates the actual exhaust gas temperature when the vehicle control of the present embodiment is applied, and the broken line indicates the exhaust when the vehicle control of the present embodiment is not applied. The gas temperature is shown.

  As shown at times t2 to t3, in a situation where the calculated exhaust gas temperature of the hybrid vehicle 1 is lower than the activation temperature of the NOx purification catalyst, the vehicle 4 travels in a state where the charged state of the battery 4 is equal to or lower than the lower limit threshold. Is started, running power generation is performed to increase the charge value of the battery 4 and increase the actual exhaust gas temperature.

  Further, as shown at times t5 to t6, even in a low load region (a state in which the calculated exhaust gas temperature is lower than the catalyst activation temperature at the stage immediately before time t5), the battery is temporarily stopped at the stage immediately before time t5. Since the charge value of 4 exceeds the upper limit threshold value, the engine 2 is stopped, electric power is supplied from the battery 4, and the motor generator 3 is electrically driven.

  Next, as shown at times t <b> 6 to t <b> 7, normal running by the engine 2 is performed in an operation region where the calculated exhaust gas temperature is higher than the catalyst activation temperature. Subsequently, as shown at times t7 to t8, at the stage of time 7 when the calculated exhaust gas temperature becomes lower than the catalyst activation temperature, the charge value of the battery 4 is higher than the lower limit threshold value. (In this case, the monitoring logic of the charging state during electric driving is applied).

  Subsequently, as shown at times t8 to t9, when the charge value of the battery 4 reaches the lower limit threshold during electric travel (time t8), the battery is shifted from the electric travel mode to the travel power generation mode. 4 and the actual exhaust gas temperature are increased.

  Times t11 to t12 are the same as the times t2 to t3. Subsequently, as shown at times t12 to t13, when the charged value of the battery 4 reaches the upper limit threshold again by running power generation, electric running in the low load region is started. Times t13 to t14 are the same as the above times t6 to t7. Time t14 to t15 is the same as time t7 to t8.

  Thus, in the hybrid vehicle 1 according to the present embodiment, when the engine 2 is running, the exhaust gas can be efficiently purified by keeping the exhaust gas temperature higher than the activation temperature of the purification catalyst. In addition, when the exhaust gas temperature becomes low when the engine 2 is operated, the engine 2 in a state where the exhaust gas temperature is low and the engine efficiency is low by properly using driving power generation and electric driving according to the state of charge of the battery 4. Can avoid driving. Therefore, both efficient purification of exhaust gas and improvement of fuel consumption can be achieved.

  A vehicle and a control method thereof according to the present invention include an internal combustion engine and a motor generator as power sources, and include an exhaust gas purification device that purifies exhaust gas generated by the operation of the internal combustion engine by a catalytic action. In a vehicle including a power storage device capable of charging electric power, it is possible to achieve both efficient purification of exhaust gas and improvement of fuel consumption, and therefore, it can be used for a vehicle such as an automobile and a control method thereof.

1 Diesel hybrid vehicle (vehicle)
2 Diesel engine (internal combustion engine)
3 Motor generator 4 Battery (power storage device)
14 Electronic control unit (control unit)
15 Exhaust pipe 16 Exhaust gas purification device

Claims (4)

Provided with an internal combustion engine and a motor generator as a power source, an exhaust gas purification device that purifies exhaust gas generated by the operation of the internal combustion engine by catalytic action, and a power storage device that can charge the electric power of the motor generator In the vehicle,
When the internal combustion engine is operated, when the exhaust gas temperature is higher than a preset temperature related to the activation temperature of the catalyst of the exhaust gas purifying device, traveling by the internal combustion engine is performed,
When the temperature of the exhaust gas is lower than the set temperature, the charge state of the power storage device is monitored,
When it is determined that the charging state is a charging state that can be driven by the motor generator with reference to a preset first set charging value, the driving by the motor generator is performed,
If it is determined that the motor generator is in a charge state that cannot be traveled based on the first set charge value, control is performed to generate power while operating the internal combustion engine and charge the power storage device. A vehicle having a control unit. The controller monitors the state of charge of the power storage device during traveling by the motor generator,
When it is determined that the state of charge is a state of charge that can be traveled by the motor generator based on a second set charge value that is preset at a value lower than the first set charge value, the electric motor Continue running with the generator,
If it is determined that the motor generator is in a state of charge that cannot be traveled on the basis of the second set charge value, control is performed to generate power while operating the internal combustion engine and charge the power storage device. The vehicle according to claim 1. Provided with an internal combustion engine and a motor generator as a power source, an exhaust gas purification device that purifies exhaust gas generated by the operation of the internal combustion engine by catalytic action, and a power storage device that can charge the electric power of the motor generator In a vehicle control method,
When the internal combustion engine is operated, when the exhaust gas temperature is higher than a preset temperature related to the activation temperature of the catalyst of the exhaust gas purifying device, traveling by the internal combustion engine is performed,
When the temperature of the exhaust gas is lower than the set temperature, the charge state of the power storage device is monitored,
When it is determined that the charging state is a charging state that can be driven by the motor generator with reference to a preset first set charging value, the driving by the motor generator is performed,
Control of the vehicle that generates power while operating the internal combustion engine and charges the power storage device when it is determined that the motor generator does not allow traveling based on the first set charge value Method. During traveling by the motor generator, monitoring the state of charge of the power storage device,
When it is determined that the state of charge is a state of charge that can be traveled by the motor generator based on a second set charge value that is preset at a value lower than the first set charge value, the electric motor Continue running with the generator,
The power storage device is configured to generate electric power while operating the internal combustion engine and charge the power storage device when it is determined that the electric power generation is impossible with the motor generator based on the second set charge value. The vehicle control method described.

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