JP2012153287A - Hybrid vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid vehicle control device that enables the vehicle always run in a best condition of efficiency of energy without deteriorating the drivability.SOLUTION: The hybrid vehicle control device includes an internal combustion engine and an electric motor as drive power sources, and can control the idling rotation speed of the internal combustion engine in the EV driving. The device is provided with: an idling rotation speed holding means (step S7) that holds the idling speed by the holding speed that is raised toward the target rotation speed of the internal combustion engine; a combustion efficiency estimation means (step S9) that estimates the combustion efficiency of the internal combustion engine; and a fuel supply determination means (steps S8, S9 and S10) that determines whether the internal combustion engine is made idling or combustion driving based on the estimated combustion efficiency estimated when the internal combustion engine is carried out combustion driving with the holding rotation speed when the internal combustion engine is held by the holding rotation speed.

Description

  The present invention relates to a hybrid vehicle including an internal combustion engine and an electric motor having a power generation function as a driving force source for traveling of the vehicle, and is particularly configured to be able to control the rotational speed of the internal combustion engine by the electric motor. The present invention relates to a control device for a hybrid vehicle.

  A hybrid vehicle is a vehicle in which an internal combustion engine such as a gasoline engine or a diesel engine and an electric motor such as a motor / generator are mounted as a plurality of driving force sources, and fuel consumption is improved while taking advantage of the characteristics of the internal combustion engine and the electric motor. It is possible to improve and reduce exhaust gas. In other words, a hybrid vehicle having an internal combustion engine and an electric motor as driving force sources can operate the internal combustion engine at an operating point with good combustion efficiency, and can add the driving torque required for the vehicle with the electric motor. Sometimes the energy is regenerated and the electric power generated at that time can be used for running. Therefore, the fuel efficiency can be improved while satisfying the demand for traveling, and the exhaust gas can be reduced. An example of an invention relating to such a hybrid vehicle is described in Patent Document 1.

  The invention described in Patent Document 1 is a control device for a hybrid vehicle including an internal combustion engine and a motor, and an EV mode for generating a drive torque in the motor while fuel supply to the internal combustion engine is stopped, and an internal combustion engine. The HV mode for generating torque in the engine is appropriately switched, and the state of charge of the battery is detected. When the state of charge is good, the internal combustion engine is driven under the EV mode, and the state of charge is poor. The internal combustion engine is prohibited from being rotated. Further, in this Patent Document 1, in order to quickly reach the target rotational speed after switching from the EV mode to the HV mode, the internal combustion engine is stopped while the combustion of the internal combustion engine is stopped in the EV mode. When it is determined that the current travel path corresponds to a slope based on the point that causes the rotation or, for example, information acquired from the navigation device, switching to the HV mode is frequently repeated in subsequent travel. The point at which the internal combustion engine is rotated in the EV mode, or the level of the rotational speed when the internal combustion engine is rotated is adjusted according to the frequency of switching to the HV mode. Etc. are disclosed.

  Patent Document 2 also discloses that when starting an engine by starting combustion of the engine during running of the motor, the engine stopped at combustion is rotated at a predetermined rotational speed in order to start up the engine speed early. Points to be determined, whether the vehicle is traveling on or near an uphill road by navigation information, and starting the engine when the battery SOC falls below a predetermined value In addition, a point that switches between engine rotation and engine rotation stop based on a driver's request is disclosed.

  In Patent Document 3, when the engine and the generator are operating and outputting torque, the torque fluctuation in that case is absorbed by the correction torque output by the motor, thereby providing a running feeling due to torque fluctuation. A technique for suppressing the deterioration of the above is disclosed.

JP 2009-298269 A International Publication No. 2007/060853 Japanese Patent Laid-Open No. 10-231743

  According to the hybrid vehicle as described in Patent Document 1 and Patent Document 2 described above, by so-called EV traveling that drives the vehicle only by the output of the electric motor, and by the output of the internal combustion engine or the outputs of both the internal combustion engine and the electric motor. The vehicle can be driven by appropriately switching between so-called HV driving for driving the vehicle. Then, during EV travel, by appropriately controlling the rotation speed of the electric motor (in the hybrid vehicle described in Patent Document 1, the motor generator 14 and the motor 16), the internal combustion engine is idling while the combustion of the internal combustion engine is stopped. In other words, it is possible to cause the internal combustion engine to rotate. Therefore, for example, when there is a request for acceleration to a vehicle that is traveling in EV, the rotational speed of the motor is controlled when the traveling state of the vehicle is switched from EV traveling to HV traveling in order to generate torque in the internal combustion engine. When the vehicle is re-accelerated by the output of the internal combustion engine in response to the acceleration request by idling the internal combustion engine and maintaining the idling rotation speed (that is, the rotation speed) at a predetermined rotation speed or higher in advance. Response delay can be avoided or suppressed.

  However, in order to avoid the response delay at the time of reacceleration as described above, for example, a state in which the vehicle is traveling on a flat road is set to a predetermined rotational speed that serves as a reference when setting the idling rotational speed of the internal combustion engine. If the vehicle is calculated based on the above, the rotational speed and output required when the vehicle re-accelerates on the uphill road may be insufficient. On the other hand, if the above-mentioned predetermined rotational speed is calculated based on the state where the vehicle is traveling on an uphill road, the rotational speed becomes excessively high when the vehicle is reaccelerated on a flat road or a downhill road. There is. As a result, response delays during re-acceleration cannot be properly avoided, and the drivability of the vehicle is reduced, or power is wasted due to the excessive increase in the rotational speed of the internal combustion engine. There is a case. Furthermore, depending on the idling speed of the internal combustion engine, it may be necessary to regenerate by supplying fuel to the internal combustion engine and driving the electric motor with the output of the internal combustion engine rather than idling the internal combustion engine with the fuel supply stopped. As a result, energy efficiency may be good.

  As described above, in a hybrid vehicle having an internal combustion engine and an electric motor as driving force sources, the vehicle driver is driven even when an acceleration request or a deceleration request is made to the vehicle, for example, when EV traveling is performed by the output of the electric motor. There is still room for improvement in order to allow the vehicle to always run with optimum energy efficiency without sacrificing performance.

  The present invention has been made paying attention to the above technical problem, and in a hybrid vehicle equipped with an internal combustion engine and an electric motor as driving force sources, the energy efficiency is always in the best state without reducing drivability. An object of the present invention is to provide a control device for a hybrid vehicle that can be driven.

  In order to achieve the above object, an invention according to claim 1 is provided with an internal combustion engine and an electric motor as driving force sources, stops supplying fuel to the internal combustion engine, and generates a driving torque only for the electric motor. An EV traveling to travel and an HV traveling to supply a fuel to the internal combustion engine and generate a driving torque in the internal combustion engine to travel the vehicle can be selectively executed, and the internal combustion engine can be operated during the EV traveling. In the hybrid vehicle control device capable of controlling the idling rotation speed at that time, when the running state of the vehicle is switched from the EV running to the HV running, the idling revolution number of the internal combustion engine is Idling that is held at an increased holding speed so as to reduce the deviation from the target speed required to output the target torque required for the internal combustion engine when starting HV traveling Number holding means, combustion efficiency estimating means for estimating combustion efficiency when fuel is supplied to the internal combustion engine and the internal combustion engine is operated for combustion, and when the rotation of the internal combustion engine is held at the holding speed And fuel supply determining means for determining whether the internal combustion engine is idling or burning based on an estimated combustion efficiency estimated when the internal combustion engine is operated at the holding rotational speed. Is a control device characterized by

  According to a second aspect of the present invention, in the first aspect of the present invention, the fuel supply determining means is configured to calculate the estimated combustion efficiency and the theoretical optimum combustion efficiency when the internal combustion engine is operated at the holding rotational speed. The control device includes means for performing a combustion operation of the internal combustion engine when the deviation is smaller than a predetermined threshold value set in advance.

  According to the first aspect of the present invention, when the hybrid vehicle is switched from the state in which the hybrid vehicle is EV driven by the output of the electric motor to the state of HV traveling by the combustion operation, before the combustion operation of the internal combustion engine is started, The rotational speed of the internal combustion engine is increased toward the target rotational speed at the start of the combustion operation and is held at the holding rotational speed. Therefore, it is possible to eliminate the response delay of the internal combustion engine speed when switching from EV traveling to HV traveling and realize smooth switching, and as a result, it is possible to avoid a decrease in drivability. When the internal combustion engine is held at the holding rotational speed when starting the HV traveling as described above, the combustion efficiency when the internal combustion engine is burned at the holding rotational speed is taken into consideration. The engine is idled or burned. Therefore, even when the traveling state of the hybrid vehicle is switched, the internal combustion engine can be rotated in a state where the efficiency is always good, and the energy efficiency of the hybrid vehicle can be improved.

  According to the second aspect of the present invention, the estimated combustion efficiency predicted when the internal combustion engine is burned at the holding rotational speed is compared with the theoretical optimum combustion efficiency, and the rotational speed of the internal combustion engine is reduced. It is determined whether the internal combustion engine is idling or burning when held at the holding speed. Therefore, the internal combustion engine can be rotated by appropriately determining an efficient state, and the energy efficiency of the hybrid vehicle can be appropriately improved.

It is a flowchart for demonstrating an example of control by the control apparatus of this invention. It is a schematic diagram which shows an example of the combustion efficiency map of the internal combustion engine applied to the hybrid vehicle made into the control object by this invention. It is a figure for demonstrating the relationship between the prediction (necessary) acceleration calculated when performing the control shown to the flowchart of FIG. 1, and a vehicle speed. FIG. 2 is a diagram for explaining a relationship between a predicted (necessary) acceleration calculated when executing the control shown in the flowchart of FIG. 1 and a speed difference between an actual vehicle speed and a limited vehicle speed. It is a time chart for comparing the case where control by the control device of the present invention is executed and the case where conventional control is executed. It is a schematic diagram which shows an example of a structure of the hybrid vehicle made into the object of control by this invention.

  Next, the present invention will be specifically described with reference to the drawings. FIG. 6 is a configuration example of a hybrid vehicle according to the present invention, and schematically shows a configuration of a so-called two-motor type hybrid vehicle. That is, the hybrid vehicle shown in FIG. 6 includes the internal combustion engine 1 and the two electric motors 2 and 3 as drive power sources, and divides the power of the internal combustion engine 1 into the electric motor 2 and the output shaft 4. It is configured.

  The internal combustion engine 1 is a power engine that outputs power by burning fuel such as a gasoline engine, a diesel engine, or a natural gas engine. In the example shown in FIG. 6, a load such as a throttle opening is electrically controlled. It is equipped with an electronically controlled throttle valve or electronically controlled fuel injection device that can be set to the optimum operating point with the best fuel efficiency by electrically controlling the rotational speed for a given load. A gasoline engine that can be used. Hereinafter, in the description of this embodiment, the internal combustion engine 1 is referred to as the engine 1.

  Each of the electric motors 2 and 3 is an electric motor having a function of either one or both of a motor and a generator. In the example shown in FIG. 6, a motor that has both a function as a motor and a function as a generator. A generator is installed. Hereinafter, in the description of this embodiment, the electric motors 2 and 3 are referred to as a first motor / generator (MG1) 2 and a second motor / generator (MG2) 3.

  A planetary gear mechanism 5 having a differential action is provided as a power split mechanism for splitting the power of the engine 1 into the first motor / generator 2 and the output shaft 4. In the example shown in FIG. A single-pinion type planetary gear mechanism is employed in which a pinion gear disposed between the ring gear 5r and the ring gear 5r is held by a carrier 5c so as to be able to rotate and revolve. The engine 1 is connected to the carrier 5c, the first motor / generator 2 is connected to the sun gear 5s, and the output shaft 4 is connected to the ring gear 5r.

  As described above, the first motor / generator 2 is an electric motor having a power generation function, and the power split mechanism, that is, the planetary gear mechanism 5 performs a differential action, so that the first motor / generator 2 corresponds to the rotation speed of the first motor / generator 2. The engine 1 changes in speed, so that the engine speed of the engine 1 can be controlled by the first motor / generator 2. For example, during the so-called EV travel where the fuel supply to the engine 1 is stopped and the vehicle is driven by the output of only the first motor / generator 2 and / or the second motor / generator 3, the engine 1 is rotated and idles. Even in such a case, the rotational speed of the engine 1 (that is, the idling rotational speed) can be adjusted. That is, by controlling the rotational speed of the first motor / generator 2 and / or the second motor / generator 3, the idling rotational speed of the engine 1 can be controlled.

  The first motor / generator 2 is connected to the power storage device 7 via an inverter 6. That is, the inverter 6 is configured to control the amount of power generated by the first motor / generator 2 and the torque or rotational speed when the first motor / generator 2 functions as an electric motor. Further, the second motor / generator 3 described above is connected to the output shaft 4, and the second motor / generator 3 is connected to the power storage device 7 via another inverter 8.

  Further, the motor generators 2 and 3 are configured to be able to supply power to each other. That is, when the first motor / generator 2 functions as a generator, the electric power is supplied to the second motor / generator 3 so that the second motor / generator 3 functions as an electric motor. After a part is converted into electric power, the power is transmitted to the output shaft 4.

  An electronic control unit (ECU) 9 for controlling the operating state of the engine 1 and the motor / generators 2 and 3 is provided. The electronic control device 9 detects a braking request such as a sensor that detects a vehicle speed such as a wheel speed sensor, an acceleration sensor that detects the acceleration of the vehicle, a sensor that detects an acceleration request such as an accelerator opening sensor, and a brake switch. Sensor, sensor for detecting the engine speed of the engine 1, sensor for detecting the charge amount of the power storage device 7, sensor for detecting the speed of each of the motor generators 2 and 3, and sensor for detecting the speed of the output shaft 4 Detection signals from various sensor devices are input. On the other hand, the electronic control unit 9 is configured to output a signal for controlling the engine 1, a signal for controlling the motor / generators 2 and 3 (that is, the inverters 6 and 8), and the like.

  As described above, the vehicle to be controlled in the present invention has a plurality of driving force sources of the internal combustion engine and the electric motor, generates EV driving torque only in the electric motor, and travels the vehicle. This is a hybrid vehicle capable of selectively switching between HV traveling in which fuel is supplied and so-called combustion operation is performed to generate driving torque in the internal combustion engine and the vehicle travels. In such a hybrid vehicle, for example, the idling speed of the internal combustion engine can be controlled at the time of switching from EV travel to HV travel, so that the response delay of the internal combustion engine speed at the time of switching from EV travel to HV travel is eliminated. And smooth switching can be realized. However, when the control is performed as in the prior art, the overall energy efficiency is better when the internal combustion engine is operated by combustion and the electric motor is driven by the output of the internal combustion engine to perform regeneration than by idling the internal combustion engine. There was a possibility.

In view of this, the control device according to the present invention is configured such that control for always traveling in the best state of energy efficiency can be executed without reducing drivability. An example of the control is shown in the flowchart of FIG. The routine shown in this flowchart is repeatedly executed every predetermined short time. In FIG. 1, first, a required acceleration (predicted acceleration) G _est is calculated (step S1), and then an output (predicted required output) P _outtgt necessary for obtaining the required acceleration G _est is calculated. (Step S2). This is to predict the necessary acceleration in the vehicle during EV traveling, and to maintain the rotational state of the engine 1 at the engine speed at which the engine 1 can output the torque necessary to obtain the necessary acceleration. Control.

Here, assuming that the vehicle weight is M and the running load resistance at the current running vehicle speed is Frl, the driving force Ftg necessary to obtain the required acceleration G _est is:
F _tg = M ・ G _est + F _rl・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (1)
Represented as: Although it is possible to calculate the necessary acceleration G _est from this equation (1), it is necessary to drive the vehicle at a constant speed when the vehicle is traveling on an uphill road having an inclination angle of θ degrees, for example. When determining the driving force, it is necessary to add M, g, and tan θ to the traveling load resistance _Frl . That is, if the required acceleration obtained by the driving force F _tg obtained from the formula obtained by replacing “F _rl ” in the above equation (1) with “F _rl + M · g · tan θ” is G _est ′,
G _est '= (F _tg −F _rl ) / M−g · tan θ (2)
Next, 'when compared with the (1) the required acceleration G _est obtained from the equation, the required acceleration G _est' This requires acceleration G _est will decrease the "g · tan .theta" partial acceleration than the required acceleration G _est . Therefore, when the required acceleration is calculated based on the above equation (1) when the vehicle is traveling on an uphill road with an inclination angle of θ degrees, the actual required acceleration is insufficient by “g · tanθ”. become.

Thus, if the required acceleration calculated | required here falls, the rotation speed of the engine 1 must be raised by the part, and it will become a factor of the response delay of control. In contrast, when calculating the necessary acceleration G _est, by calculating the necessary acceleration G _est and by adding the content "g · tan .theta" according to the inclination angle θ of the road, avoiding the response delay of the control An appropriate necessary acceleration G _est that can be obtained can be obtained.

When the required acceleration G _est and the required output P _outtgt are calculated in the above-described steps S1 and S2, the gradient grade of the travel path on which the vehicle is currently traveling is obtained, and the absolute value of the gradient grade is preset. It is determined whether or not it is larger than a predetermined threshold grdth (step S3). If the absolute value of the gradient grade is larger than the threshold value grdth, if the determination in step S3 is affirmative, the process proceeds to step S4, and the gradient correction output P _outadjgd is calculated.

  Here, the gradient grade is, for example, a vehicle that is running based on detection values such as a torque sensor that detects the output shaft torque of the engine 1, a rotation speed sensor that detects the rotation speed of the output shaft, and a wheel speed sensor. , And the gradient grade of the traveling road surface can be estimated based on the longitudinal acceleration. Further, by providing a gradient sensor in the vehicle, the gradient grade can be obtained based on the detected value of the gradient sensor.

When the absolute value of the gradient grade exceeds the threshold value grdth, as described above, when the required acceleration G _est is calculated, it is greatly affected by the gradient grade of the traveling road, and correction according to the inclination angle θ of the gradient grade is performed. It is judged necessary. Therefore, in this step S4, the gradient correction output P _outadjgd is obtained as the output of the engine 1 necessary for generating the acceleration component corrected in consideration of the aforementioned “g · tan θ”.

Subsequently, a predicted engine speed Ne _outtgt is calculated (step S5). The predicted engine speed Ne _outtgt is the engine speed required when the engine 1 outputs the output obtained by adding the gradient correction output P _outadjgd obtained in step S4 (ie, “P _outtgt + P _outadjgd ”). As required.

On the other hand, if the absolute value of the gradient grade of the travel path on which the vehicle is currently traveling is equal to or less than the threshold value grdth, the determination in the above step S3 is negative, the step S4 is skipped, and the above step S5. Control is performed in the same way. That is, when the absolute value of the gradient grade is less than or equal to the threshold value grdth, it can be determined that there is little influence from the gradient grade of the travel path when calculating the required acceleration G _est and no correction is necessary. Correction is not performed, and the predicted engine speed Ne _outtgt is determined as the engine speed required when the engine 1 outputs the necessary output P _outtgt determined in step S2.

When the predicted engine speed Ne _outtgt is obtained, the predicted engine speed Ne _outtgt is compared with the current engine speed Ne _cur of the engine 1, and the current engine speed Ne _cur is calculated from the predicted engine speed Ne _outtgt . Is also determined (step S6). If the current engine speed Ne _cur is less than or equal to the predicted engine speed Ne _outtgt and if a negative determination is made in step S6, the process proceeds to step S7, where the current engine speed Ne _cur, that is, the actual engine 1 The idling engine speed Ne _cur is controlled to coincide with the predicted engine engine speed Ne _outtgt . For example, by controlling the rotational speed of the first motor-generator 2, with is raised so that the engine rotational speed Ne _cur is consistent with the predicted engine speed Ne _Outtgt, is held at the predicted engine speed Ne _Outtgt . That is, the predicted engine speed Ne _outtgt corresponds to the holding speed in the present invention.

Note that the idling speed Ne _cur of the engine 1 as described above is controlled by controlling the number of revolutions of the second motor generator 3 in addition to that by the first motor / generator 2. You can also control _cur . Alternatively, the idling rotation speed Ne _cur of the engine 1 can be controlled by controlling both the rotation speed of the first motor / generator 2 and the rotation speed of the second motor generator 3. Further, for example, a transmission mechanism that can be controlled by changing the transmission ratio, a clutch mechanism that can perform slip control, and the like are provided between the crankshaft of the engine 1 and the rotation shaft of the first motor / generator 2. It is also possible to control the idling speed Ne _cur of the engine 1 by controlling the gear ratio of the transmission mechanisms and the engagement state of the clutch mechanism.

As described above, the actual engine speed of the engine 1, that is, the idling speed Ne _cur is controlled by the first motor / generator 2 and is made to coincide with the predicted engine speed Ne _outtgt in advance, so that the output to the vehicle can be increased. When fuel is supplied to the engine 1 in response to an increase request and the combustion operation of the engine 1 is started, there is no need to wait for an increase in the engine speed, and only the first motor / generator 2 and the second motor / generator 3 are required. Switching from the EV traveling state in which the vehicle is driven by the output to the HV traveling in which the vehicle is driven by the combustion operation of the engine 1 can be performed quickly and smoothly.

Further, when calculating the predicted engine speed Ne _outtgt described above, the power consumption when controlling the rotation of the first motor / generator 2 in order to increase the idling speed Ne _cur of the engine 1 and the engine 1 In consideration of the fuel consumption, the predicted engine speed Ne _outtgt is calculated so that the power consumption of the first motor / generator 2 and the fuel consumption of the engine 1 are minimized. Energy efficiency can be improved.

On the other hand, if the current engine speed Ne _cur is higher than the predicted engine speed Ne _outtgt , it is not necessary to further increase the engine speed Ne _cur if the determination in step S6 is affirmative. Therefore, the above step S7 is skipped, and the control after the next step S8 is executed.

As described above, when the control for increasing the idling rotational speed Ne _cur of the engine 1 at the time of switching from the EV traveling to the HV traveling as described above is performed, the conventional control can always perform the control with the best energy efficiency. Not always. That is, rather than idling the engine 1, the energy efficiency of the entire hybrid vehicle may be improved when the engine 1 is burned and the first motor / generator 2 is driven by the output of the engine 1 to perform regeneration. there were. Therefore, the control device according to the present invention is configured to execute the control in the next step S8 and subsequent steps.

  In step S8, it is determined whether fuel injection to the engine 1 is stopped. That is, it is determined whether the fuel supply to the engine 1 is stopped or the fuel is supplied to the engine 1. In other words, it is determined whether the engine 1 is idling or in a combustion operation.

  If the determination is negative in step S8 because the fuel has already been supplied to the engine 1, that is, the engine 1 is in the combustion operation, the switching from the EV traveling to the HV traveling has already been performed. Since it is in the performed state, it is not necessary to execute the subsequent control. Therefore, this routine is temporarily ended without executing the control of the subsequent steps S9 and S10.

On the other hand, when the fuel supply to the engine 1 is in a stopped state, that is, when the engine 1 is idling and the determination is affirmative in step S8, the process proceeds to step S9. The deviation between the combustion efficiency fcef when the engine 1 is burned at the predicted engine speed Ne _outtgt and the torque T _tl and the theoretical optimum combustion efficiency fcid at the predicted engine speed Ne _outtgt is the optimum fuel efficiency operation of the engine 1 It is determined whether or not it is smaller than a predetermined threshold value fcthr set in advance to determine the state. Here, the torque T _tl is the total torque of the driver's required drive torque T ₁ and the torque T ₂ required to hold the engine 1 at the predicted engine speed Ne _outtgt . Note that the combustion efficiency fcef and the optimum combustion efficiency fcid described above are the combustion efficiency contour line and the optimum combustion efficiency line (the combustion efficiency contour line and the optimum combustion efficiency line ( The combustion efficiency map indicated by the fuel efficiency optimum operation line) is set in advance, and can be obtained based on the combustion efficiency map.

If the difference between the combustion efficiency fcef and the optimum combustion efficiency fcid is smaller than the threshold value fcthr, if the determination in step S9 is affirmative, the process proceeds to step S10 where fuel is supplied to the engine 1 and the engine 1 The combustion operation is started or restarted. For example, when the engine 1 includes an electronically controlled fuel injection device, fuel is injected into the engine 1 and the engine 1 is operated for combustion. That is, in this case, the difference between the combustion efficiency fcef predicted when the combustion operation is performed at the predicted engine speed Ne _outtgt and the torque T _tl and the theoretically optimum combustion efficiency fcid is small, and the engine 1 speed is predicted. Since it can be judged that the efficiency is higher when fuel is supplied and burned than when the engine 1 is idling to maintain the engine speed Ne _outtgt , the fuel is supplied to the engine 1 and the combustion operation starts. Is done. Thereafter, this routine is once terminated.

On the other hand, if the deviation between the combustion efficiency fcef and the optimum combustion efficiency fcid is equal to or greater than the threshold value fcthr, and if a negative determination is made in step S9, the routine does not execute the control in step S10. Is temporarily terminated. That is, in this case, there is a large difference between the combustion efficiency fcef estimated when the engine 1 is burned and operated at the predicted engine speed Ne _outtgt and torque T _tl and the theoretically optimum combustion efficiency fcid. Since it can be determined that the efficiency is deteriorated when fuel is supplied to the engine 1 and the combustion operation is performed when the engine _speed is maintained at the predicted engine speed Ne _outtgt , the engine 1 is not supplied with fuel, and the vehicle inertia force and the 1 The engine 1 is idled by the output of the motor / generator 2.

Thus, in the control in step S7 to step S10 in the above, the total torque T _tl between the torque T ₂ of the order to hold the predicted engine speed Ne _Outtgt the required driving torque T _1, an engine rotational speed of the target When the fuel supply to the engine 1 is started in relation to the Ne _tag , the combustion efficiency that can be taken on the combustion efficiency line of the combustion efficiency map of the engine 1 shown in FIG. 2 is fcef, and the engine speed ( Alternatively, the optimum combustion efficiency in engine torque) is fcid. When the combustion efficiency fcef and the optimal combustion efficiency fcid are equal or approximately equal, the first motor / generator 2 and the second motor / generator 3 can output the torques T ₁ and T _2. Even in this case, by starting the fuel supply to the engine 1 and switching the operating state of the first motor / generator 2 from the power running to the regeneration, the motor torque can be reduced, and both the fuel consumption and the power consumption can be reduced. The above control can be executed in a minimum state.

Incidentally, in the control shown to step S7 to not step S1 in the flowchart of FIG. 1 described above, when obtaining the necessary acceleration G _est, best necessary acceleration G _est varies depending on the driving conditions and the operating conditions of the vehicle. For example, when the vehicle travels on an uphill road with a large inclination angle θ, the change in the vehicle speed due to the running resistance increases, and therefore the required acceleration G _est for adjusting the vehicle speed is increased according to the magnitude of the inclination angle θ. . Therefore, if the inclination angle θ is small, the necessary acceleration G _est may be reduced accordingly.

Further, when traveling at a low speed, there is a high possibility that the vehicle is required to have an acceleration up to a certain level of vehicle speed, for example, about 30 to 40 km / h. Therefore, the required acceleration G _est is set large, and the vehicle speed range above the certain level. Then, by making the necessary acceleration G _est constant, control according to the driving environment becomes possible. More specifically, for example, as shown in FIG. 3, in a low vehicle speed range up to a vehicle speed a of about 30 to 40 km / h, a relatively large necessary acceleration G _est is set, and for example, around 100 km / h from the vehicle speed a. Control is executed more appropriately by setting a relatively small required acceleration G _est in the medium vehicle speed range up to the vehicle speed b, and by setting the required acceleration G _est constant in the high vehicle speed range above the vehicle speed b. be able to.

  However, when driving at an extremely low vehicle speed of, for example, about 10 km / h or less, there is a possibility that the driver may feel uncomfortable if the engine speed becomes high. Therefore, since the motor is in a travel region where the maximum torque is likely to be generated, it is preferable not to execute the engine speed increase control for maintaining the engine speed.

In addition, for example, the vehicle speed limit information is input from the car navigation information or road traffic information communication system (VICS) information, and the required acceleration G _est is changed and set according to the difference between the vehicle speed limit and the actual vehicle speed. It is preferable to do this. For example, as shown in FIG. 4, when the current vehicle speed is lower than the limit vehicle speed, it is predicted that the vehicle will be accelerated within a short time until the limit vehicle speed. Therefore, according to the vehicle speed difference, that is, the vehicle speed difference The required acceleration G _est is set so as to increase as the value increases. When the current vehicle speed exceeds the limit vehicle speed, the possibility that the vehicle is further accelerated is reduced, so the necessary acceleration G _est is set to be small or zero. By doing so, the driver's intention can be appropriately reflected in the control. Further, the inter-vehicle distance from the preceding vehicle is determined from a camera, a radar device, etc., and if the inter-vehicle distance is large, the necessary acceleration G _est is set large, and if the inter-vehicle distance is small, the necessary acceleration G _est is decreased. Can be set.

Further, when the engine 1 is kept at the predicted engine speed Ne _outtgt , for example, when the _vehicle is approaching an uphill road from a state of running on a flat road, the driving force necessary for the uphill road travel is required in advance. And the engine 1 is held at the engine speed for realizing the output of the engine 1 necessary to obtain the estimated driving force before the vehicle enters the uphill road. Is preferred. By doing so, it becomes possible to obtain a driving force necessary for traveling on an uphill road without a response delay. On the other hand, when the vehicle approaches a downhill road where the inclination angle θ is negative, the driving force required in that case is small, so the rotational speed of the engine 1 before the vehicle enters the downhill road. Is preferably reduced. By doing so, unnecessary power consumption can be suppressed.

  In the above description, in order to consider the influence of the inclination angle θ of the traveling road surface, the gradient grade of the currently traveling road surface is obtained and reflected in the control. By replacing with the gradient information gradeest, it is possible to execute so-called look-ahead control that predicts the traveling environment. Further, in order to make the time to reach the actual gradient road from the time of executing the engine speed control in the present invention constant, the predetermined distance is changed according to the current vehicle speed so that the arrival time becomes constant. Also good.

In addition, the above-described control concept can be applied even in a situation where the vehicle speed limit of the travel path is switched. That is, when the vehicle speed limit of the planned travel route is switched from the car navigation information or the VICS information, and the vehicle speed limit of the planned travel route is higher than the current vehicle speed limit, the required acceleration G _est is set to be large. When the vehicle speed limit on the planned travel path is lower than the current vehicle speed, a higher control effect can be obtained by setting the required acceleration G _est small.

Further, when the required driving force is predicted and the engine speed required to output the required driving force (that is, the predicted engine speed Ne _outtgt ) is increased and held, the first motor When the engine speed is increased using the generator 2, an inertia torque corresponding to the changing speed of the engine speed is generated (if the engine speed is decreased, the direction opposite to that when the engine speed is increased is generated. Inert shuttle is generated). In this case, the increase in the engine speed is not caused by the driver's operation, and thus the fluctuation of the driving force due to the inertia torque causes the driver to feel uncomfortable. Therefore, by using another power source that does not depend on the engine speed other than the engine 1 and generating a torque that cancels out the decrease (or increase) of the driving force due to the inertia torque, the above-mentioned uncomfortable feeling can be obtained. Occurrence can be avoided.

Specifically, when the rotational inertia of the engine 1 is Ie and the angular acceleration is ω ′, the inertia torque generated by the change in the engine speed of the engine 1 is “Ie · ω ′”. In the configuration of the hybrid vehicle shown in FIG. 6, when the rotational speed of the engine 1 is changed by the first motor / generator 2, the inertia torque generated on the output shaft of the engine 1 is Ie · ω ′, and the gear of the planetary gear mechanism 5 is used. When the ratio is ρ, a reaction force of “Ie · ω ′ / (1 + ρ)” is generated on the output shaft. Since this causes the above-mentioned uncomfortable feeling, the torque T _tgi that can cancel out the reaction force is generated by the motor without being delayed with respect to the generation of the inertia torque, thereby increasing the acceleration to the vehicle. The engine speed of the engine 1 can be changed without any influence.

FIG. 5 is a time chart showing the behavior of the engine speed, motor torque, and vehicle acceleration (deceleration) when the above control is executed. When increasing the engine speed based on the increased demand of the engine speed at time t ₁ is started, the same motor torque is increased at the same time. This increase in motor torque is continued until time t ₂ when the increase in engine speed is completed. In the conventional example to which the present invention indicated by a broken line is not applied as a comparative example, a decrease in deceleration is observed while the engine speed is increased. However, in the application example of the present invention indicated by a solid line, there is a decrease in deceleration. It has been resolved. That is, it is possible to avoid the occurrence of an uncomfortable feeling.

Further, the inertia torque and friction torque of the engine 1 as described above may change due to the influence of individual differences of the engine 1 and changes with time. Therefore, the vehicle acceleration when the torque T _tgi for canceling the inertia torque is generated as described above is monitored, and when the vehicle acceleration changes, the change in the acceleration becomes zero. The correction learning is preferably performed in the rotation inertia Ie of the engine 1 and the control routine after the next time.

For example, when the vehicle acceleration changes by α due to the motor generating torque T _tgi that cancels the inertia torque, the cancellation torque is large by “M · α” as the driving force (small when α is negative). ) Is assumed. That is, assuming that the dynamic load radius of the tire is r and the differential gear differential ratio is if, it is assumed that the torque is increased (or decreased) by “M · α · r / if”. Therefore, it is only necessary to output a canceling torque of “T _tgi −M · α · r / if” in the next and subsequent control routines. However, since the angular acceleration ω ′ is a variable at this time, it is originally a constant term. A learning effect can be obtained by applying a corrected inertia Ie ′ obtained by correcting the rotation inertia Ie of the engine 1. Specifically, if the corrected canceling torque is T _tgi ′, the corrected canceling torque T _tgi ′ is
T _tgi '= Ie' · ω '/ (1 + ρ) = Ie · ω' / (1 + ρ) -M · α · r / if
Can be calculated as

Further, the required acceleration G _est may be different depending on the driver's preference, habit, and the like. Therefore, it is preferable to determine such a driver's preference and habit and set the necessary acceleration G _est according to each driver. Specifically, when the required acceleration G _est is changed and set based on the difference between the above-described limited vehicle speed and the current vehicle speed, for example, when the driver drives the vehicle in compliance with the limited vehicle speed, However, the required acceleration G _est differs depending on _whether the vehicle is traveling while maintaining a vehicle speed lower than the limit vehicle speed. Therefore, the vehicle speed difference between the average traveling vehicle speed and the limited vehicle speed of the driver is obtained, and if the vehicle speed difference is larger than a preset specified value, it is determined that the driver has a high traveling speed, and the required acceleration is higher than usual. Set G _est large. On the other hand, when the vehicle speed difference is smaller than the specified value (or minus), it is determined that the driver has a low traveling speed, and the necessary acceleration G _est is set smaller than usual. The difference between the limited vehicle speed and the traveling speed can be determined based on, for example, data when the driver travels in compliance with the limited vehicle speed. Alternatively, the constant speed traveling state can be determined from the vehicle acceleration, and the driver's preference for the traveling speed can be determined from the difference between the average vehicle speed and the limited vehicle speed during the constant speed traveling. Alternatively, the driver's preference for acceleration can be determined based on the average accelerator opening by the driver during acceleration.

More specifically, in the case of a driver who performs a driving operation at an accelerator opening degree that generates an acceleration higher than the required acceleration G _est at a high frequency with respect to the required acceleration G _est set as described above, Judging that the acceleration direction is strong, the required acceleration G _est is set to a large value, and conversely, the driving operation is performed at an accelerator opening degree that generates only an acceleration less than the required acceleration G _est at a high frequency with respect to the required acceleration G _est . In the case of the driver who performs, the acceleration direction is determined to be weak, and the necessary acceleration G _est is set small. By doing so, it is possible to execute control in accordance with various driver preferences and habits. Moreover, even if it is the same driver | operator, driving | running preference may be considered to change with the condition and feeling at the time of driving | running | working. For this reason, for example, it is possible to sample data used as a judgment material within a predetermined period and reflect it in the control. Furthermore, as a device that allows the driver to set his / her preference, for example, a pattern select switch, a navigation device, etc. are provided, and it is possible to select and set “power mode”, “eco mode”, etc. it can.

  In the control shown in steps S7 to S10 in the flowchart of FIG. 1 described above, the fuel is supplied to the engine 1 only when the combustion efficiency of the engine 1 is optimal, and the combustion operation is performed. When the state in which the optimum state cannot be determined immediately continues for a long time, it is conceivable that the charge amount of the power storage device 7 that supplies power to the first motor / generator or the like decreases and the function deteriorates. Therefore, when the charge amount of the power storage device 7 falls below a predetermined value set in advance, the fuel supply to the engine 1 is started by increasing the threshold value fcthr for determining the optimum fuel economy operation state of the engine 1 described above. The (or return) condition can be relaxed, and the first motor / generator 2 can be configured to suppress power consumption when controlling the idling speed of the engine 1. In this case, the specified value for determining the charge amount of the power storage device 7 may be set as a threshold value using a variable having the charge amount as a function, or a plurality of levels specified in advance according to the charge amount. The value may be appropriately switched and set as a threshold value.

Even in this case, the regenerative torque of the first motor / generator 2 is controlled to adjust the rotational speed and the output torque of the engine 1 so that the engine 1 is controlled to be in the optimum fuel consumption operation state. . Specifically, when controlling the engine 1 toward the target engine speed Ne _tag , if the above-mentioned total torque T _tl is smaller than the torque T _{fe in the} optimal fuel consumption operation state, the difference torque “T By increasing the regenerative torque of the first motor / generator 2 by “ _fe− T _tl ”, both fuel consumption and power consumption are minimized without affecting the acceleration of the vehicle, that is, without causing the driver to feel uncomfortable. In addition, an operation state in which the power storage device 7 can be charged can also be achieved.

As described above, according to the hybrid vehicle control apparatus of the present invention, the engine 1 is combusted from the state in which the vehicle is running on the EV by the output of the first motor / generator 2 and / or the second motor / generator 3. When switching to the HV running state by operating, before the combustion operation of the engine 1 is started, the idling rotation speed of the engine 1 (that is, the current engine rotation speed Ne _cur ) is the target engine rotation speed at the start of the combustion operation. And is held at the holding rotational speed (that is, the predicted engine rotational speed Ne _outtgt ). Therefore, it is possible to eliminate the response delay of the engine speed at the time of switching from EV traveling to HV traveling and realize smooth switching, and as a result, it is possible to avoid a decrease in drivability.

Then, when starting the HV running as described above, when the rotation speed of the engine 1 is held at the holding rotation speed, the combustion efficiency when the engine 1 is burned at the holding rotation speed Ne _cur is taken into consideration. The engine 1 is idled or burned. Specifically, the estimated combustion efficiency fcef predicted when the engine 1 is burned and operated at the holding rotation speed Ne _cur is compared with the theoretical optimum combustion efficiency fcid, and the rotation speed of the engine 1 is held and rotated. When the engine is held at a number Ne _cur , the more efficient one is selected as to whether the engine 1 is idling or burning. Therefore, even when the traveling state of the hybrid vehicle is switched, the engine 1 can always be rotated in a state of high efficiency, and the energy efficiency of the hybrid vehicle can be appropriately improved.

  Here, the relationship between the above-described specific example and the present invention will be briefly described. The functional means for executing step S7 corresponds to the “idling speed holding means” in the present invention, and the functional means for executing step S9. The means corresponds to “combustion efficiency estimation calculation means” in the present invention. The functional means for executing steps S8, S9, and S10 corresponds to the “fuel supply determining means” in the present invention.

  In the specific example described above, the hybrid vehicle that is the target of driving force control according to the present invention includes the engine 1 as an internal combustion engine, and the first motor / generator 2 and the second motor / generator 3 as electric motors. Although the configuration of the two-motor type hybrid vehicle has been described as an example, for example, it may be a hybrid vehicle including an engine and one motor / generator, or does not have an engine and a power generation function. A hybrid vehicle including a motor may be used. In short, as a driving force source for generating the driving force of the vehicle, a hybrid vehicle including at least an internal combustion engine such as a gasoline engine or a diesel engine and an electric motor such as a motor or a motor / generator is used as the driving force in the present invention. It can be the target of control.

  DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine (engine), 2, 3 ... Electric motor (motor generator, MG1, MG2), 4 ... Output shaft, 9 ... Electronic control unit (ECU).

Claims (2)

An EV engine having an internal combustion engine and an electric motor as a driving force source, stopping fuel supply to the internal combustion engine and generating a driving torque only for the electric motor to drive the vehicle; and supplying fuel to the internal combustion engine to supply the fuel A hybrid vehicle capable of selectively executing HV traveling in which a driving torque is generated in the internal combustion engine and causing the vehicle to travel, and capable of controlling the idling rotational speed at that time by causing the internal combustion engine to idle during the EV traveling. In the control device of
When the vehicle running state is switched from the EV running to the HV running, the idling speed of the internal combustion engine is output to output the target torque required for the internal combustion engine when the HV running is started. Idle rotation speed holding means for holding at a holding rotation speed raised so as to reduce the deviation from the required target rotation speed;
Combustion efficiency estimating means for estimating combustion efficiency when fuel is supplied to the internal combustion engine and the internal combustion engine is operated by combustion;
When the rotation of the internal combustion engine is held at the holding rotational speed, the internal combustion engine is idled or burned based on the estimated combustion efficiency estimated when the internal combustion engine is burned at the holding rotational speed. A control device for a hybrid vehicle, comprising: fuel supply determination means for determining whether to perform the control.   The fuel supply determining means is configured to detect the internal combustion engine when a deviation between the estimated combustion efficiency and a theoretical optimum combustion efficiency when the internal combustion engine is burned at the holding rotational speed is smaller than a predetermined threshold value. A control device for a hybrid vehicle, comprising means for performing a combustion operation of an engine.

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