Control device of hybrid vehicle

Abstract

To make both securement of charging amounts and improvement in fuel economy compatible in promoting charging on the basis of artificial manipulation.SOLUTION: A control device of a hybrid vehicle is provided with: a running power calculating part (a step S2) that determines running power for making the hybrid vehicle run; a total power calculating part (a step S6) that when a charging instruction part is operated to require charging into a power storage device to be promoted (a step S3), adds predetermined charging power to the running power to determine total power that should be outputted by an engine; a determining part (a step S6) that determines whether or not the total power deviates toward a high power side out of a thermal efficiency optimal power range in which thermal efficiency can be set to predetermined optimal efficiency; and a charging power limiting part (a step S7) that when it is determined that the total power deviates from the thermal efficiency optimal power range toward the high power side, limits power for charging the device so that the total power returns into the thermal efficiency optimal power range to target charging power smaller than the charging power.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a device for controlling a hybrid vehicle equipped with an internal combustion engine and a generator or a motor with a generating function (motor-generator), and in particular to a device for controlling the engine when promoting charging. [Background technology]

[0002] Hybrid vehicles are equipped with an engine and a motor or a motor-generator (hereinafter collectively referred to as the motor), and run on the driving force output by the engine and motor, or by driving the motor with electricity discharged from an electricity storage device (battery) or electricity supplied from a generator.In addition, plug-in hybrid vehicles (PHEVs) are becoming more common, with higher-capacity electricity storage devices that can be charged with electricity from external power sources or solar panels, thereby extending the driving distance of the motor.

[0003] Hybrid vehicles (HEV and PHEV) use a motor instead of an engine to drive the vehicle, and also regenerate energy, so a battery is essential. If the charging capacity of the battery is made large like that of a PHEV, the vehicle can travel longer on the motor and consume less fuel by the engine. Attempts have been made to improve fuel efficiency by manually accelerating the charging of the battery while the vehicle is running to increase the state of charge (SOC), and enabling the vehicle to run on the motor when the vehicle is subsequently driven. Devices that perform such control are described in Patent Document 1 and Patent Document 2.

[0004] The hybrid vehicle described in Patent Document 1 includes an engine, a motor capable of generating electricity, and a battery connected to the motor, and is configured to drive the motor with the power of the engine to generate electricity when a command to promote charging is issued, and to charge the battery with the generated electricity. When charging, if a command is issued to increase the amount of stored electricity, the engine and the motor are controlled so that the amount of stored electricity in the battery increases at the commanded increase rate. That is, the motor is driven by the power from the engine to generate electricity, and for the electricity generation, the engine outputs power obtained by adding a charging request power required for charging the battery to bring the amount of stored electricity to a target amount of stored electricity, limited by an upper limit charging power, which is the upper limit of the power allowed for charging the battery, to the required running power.

[0005] Also, in Patent Document 2, similar to the hybrid vehicle described in Patent Document 1, a hybrid vehicle in which charging promotion control can be executed by a switch operation is described, and when a charging promotion instruction switch is turned on, at least one of the engine and the motor is controlled to increase the power storage ratio, which is the ratio of the capacity of the power that can be discharged from the battery to the total capacity. Also, in the hybrid vehicle described in Patent Document 2, when the charging promotion instruction switch is turned off after the charging promotion control, at least one of the engine and the motor is controlled to maintain or increase the power storage ratio until a predetermined operation is performed. Note that an example of the charging promotion control described in Patent Document 2 is a control in which a target ratio, which is a target value of the power storage ratio, is set higher than the power storage ratio, and the power of the sum of the charging request power required to charge the battery so that the power storage ratio becomes the target ratio and the running request power to run the vehicle is output from the engine. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-201245 A [Patent Document 2] JP 2014-201175 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described in Patent Document 1 and Patent Document 2, when charging of a battery is promoted based on a switch operation or the like, the power output by the engine mounted as a driving force source is increased to a power obtained by adding the power required for charging to the power required for driving. In the hybrid vehicle described in Patent Document 2, the target value for charging is set higher than the charge ratio. Therefore, in the past, when a charge request was made based on a human operation during hybrid driving, the engine would output the power required for driving and the power required for the requested charging. In steady hybrid driving such as maintaining the vehicle speed, the engine is operated at an operating point where the fuel consumption of the power required at that time is as small as possible. Therefore, when a charge request is made based on a human operation, the operating point of the engine is selected so that the so-called total power obtained by adding the power required for charging to the power required for driving can be output with optimal fuel consumption.

[0008] The operating point is generally found as an intersection of an optimum fuel consumption line and an iso-power line, which are predefined on a coordinate system of output torque and revolution speed. The optimum fuel consumption line is a line drawn in a straight line through a fuel consumption region drawn by so-called contour lines, which surrounds the minimum fuel consumption region in a doughnut shape with the fuel consumption gradually increasing (deteriorating) around the center. Therefore, even if the operating point is on the optimum fuel consumption line, if the operating point is farther away from the minimum fuel consumption operating point on the high power side or low power side, i.e., if the power is higher or lower, the fuel consumption will deteriorate.

[0009] When hybrid driving is performed at an operating point that belongs to the region where fuel efficiency is minimized, if a charge request is made based on manual operation and the power for generating electricity associated with the request is relatively large, the engine operating point may move to the high power side and deviate from the region where fuel efficiency is minimal because the requested power increases by the amount of the charge request. Conventionally, the engine operating point during hybrid driving is controlled to be maintained on the optimal fuel efficiency line, but even if the operating point is on the optimal fuel efficiency line, it is outside the region where fuel efficiency is minimized, and fuel efficiency may deteriorate with the request for charge. Thus, conventionally, there was room for improvement in terms of further improving fuel efficiency when a charge request is made based on manual operation.

[0010] The present invention has been made with an eye on the above-mentioned technical problems, and aims to provide a control device for a hybrid vehicle that can achieve both ensuring the charging amount and improving fuel efficiency when promoting charging based on human operation. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides a control device for a hybrid vehicle including an engine, a generator that is driven by a portion of the power output by the engine to generate electricity, a power storage device that is connected to the generator to charge it and supply power to a motor that outputs a driving force for traveling, and a charge instruction unit that is manually operated to promote driving of the generator by the engine and charging of the power storage device from the generator, the control device having a controller that controls the operating state of the engine, the controller having a running power calculation unit that calculates the running power required for the hybrid vehicle to travel, and a charging instruction unit that is manually operated to promote charging of the power storage device. The present invention is characterized in that it has a total power calculation unit that, when a request is made to advance, adds a predetermined charging power for the charging to the traveling power to calculate a total power to be output by the engine, a determination unit that determines whether the total power is outside a thermal efficiency optimum power range to the high power side, which allows the thermal efficiency to be a predetermined optimum efficiency, and a charging power limiting unit that, when it is determined that the total power is outside the thermal efficiency optimum power range to the high power side, limits the power for the charging to a target charging power smaller than the charging power so that the total power falls within the thermal efficiency optimum power range.

[0012] In the present invention, the charging power limiting unit may be configured to subtract the traveling power from the thermal efficiency optimum power to obtain a difference between the thermal efficiency optimum power and the traveling power, and to set the target charging power to "0" if the difference is a negative value.

[0013] In the present invention, the thermal efficiency optimum power range may be a predetermined range determined based on an equal power line passing through a predetermined optimum fuel consumption region among equal fuel consumption regions obtained using the engine output torque and rotation speed as indicators. Effect of the Invention

[0014] In the present invention, when the charging instruction unit is operated to promote charging, the total power obtained by adding the power required for charging to the running power required for the hybrid vehicle to run is calculated as the power to be output by the engine. If the total power is outside the range of the optimal thermal efficiency power on the high power side, the power for charging, i.e., the target charging power, is limited so that the power to be output from the engine falls within the range of the optimal thermal efficiency power. Therefore, even if the power output by the engine is increased to promote charging, the engine is restricted from being operated outside the range of the optimal thermal efficiency power, so that deterioration of fuel efficiency can be prevented or suppressed. In addition, since the engine outputs power including the target charging power, charging can be promoted.

[0015] In particular, in the present invention, when the driving power exceeds the range of the optimal thermal efficiency power due to a large acceleration request, etc., and the power for limited power generation becomes a negative value in calculations, the target charging power is set to "0", thereby avoiding discharge from the storage device and the associated decrease in the charge amount when there is a request to promote charging, and making it possible to ensure the charge amount. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a skeleton diagram illustrating an example of a hybrid drive system. [Diagram 2] 2 is a nomographic diagram of a planetary gear mechanism constituting the power split mechanism. [Diagram 3] FIG. 4 is a block diagram for explaining control steps of engine speed and output torque. [Figure 4] FIG. 2 is a diagram showing thermal efficiency, constant power lines, and optimal fuel consumption lines in coordinates with engine torque and engine speed as parameters. [Diagram 5] FIG. 2 is a block diagram for explaining a functional configuration of a controller. [Figure 6] 4 is a flowchart illustrating an example of control executed in the embodiment of the present invention. [Figure 7]5 is a time chart showing a schematic diagram of a change in vehicle power when the control according to the present invention is performed and when the control is not performed; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will now be described with reference to the embodiments shown in the accompanying drawings. Note that the embodiments described below are merely examples of the implementation of the present invention and are not intended to limit the present invention.

[0018] First, a hybrid vehicle according to an embodiment of the present invention will be described. A hybrid vehicle has a plurality of types of power machines with different power generation modes as a driving force source, and a typical example is a vehicle using an internal combustion engine (hereinafter referred to as an engine) such as a gasoline engine or a diesel engine and an electric motor (hereinafter referred to as a motor) as a driving force source. Electricity to be supplied to the motor is generally generated by driving a generator with the engine, or by regenerating the kinetic energy of the hybrid vehicle, and the electric power is generally charged in a power storage device (hereinafter referred to as a battery) such as a secondary battery or a capacitor. Therefore, this type of hybrid vehicle has a generator and a motor, but these may be provided separately, or a motor with a power generation function (hereinafter referred to as a motor-generator) may be provided as the motor to generate electricity and drive the vehicle.

[0019] FIG. 1 is a schematic diagram showing the basic configuration of an example of a two-motor type hybrid drive system 2 mounted on a hybrid vehicle 1. A power split mechanism 4 is disposed on the output side of an engine 3, and an output shaft (crankshaft) of the engine 3 is connected to an input member of the power split mechanism 4. The power split mechanism 4 shown here is composed of a single-pinion type planetary gear mechanism 5 including a sun gear S, a ring gear R which is an internal gear disposed concentrically with the sun gear S, a plurality of pinion gears P disposed between the sun gear S and the ring gear R, which are engaged with each other and rotate and revolve, and a carrier C which holds the pinion gears P. The engine 3 is connected to the carrier C, and the carrier C serves as an input element. A first motor (MG1) 6 having a power generating function is connected to the sun gear S, and the sun gear S serves as a reaction element. The ring gear R is connected to an output member 7, and serves as an output element. A second motor (MG2) 8 having a power generating function is connected to the output member 7 or the ring gear R. Driving torque is transmitted from the output member 7 to left and right driving wheels 10 via a differential gear 9, which is a final reduction gear, to run the hybrid vehicle.

[0020] The first motor 6 and the second motor 8 are, for example, permanent magnet synchronous motors, and are each connected to a battery 12 via an inverter 11. That is, the first motor 6 and the second motor 8 are supplied with power from the battery 12 to generate driving force, and are forcibly rotated to generate power and charge the battery 12 with the power, and further, the power generated by either one of the motors 6 (or 8) is supplied to the other motor 8 (or 6) to drive the other motor 6 (or 8).

[0021] 2 shows a collinear diagram of the planetary gear mechanism 5 constituting the power split mechanism 4. The collinear diagram is a diagram in which three straight lines, a line indicating the sun gear S, a line indicating the carrier C, and a line indicating the ring gear R, are drawn parallel to one another, with the distance between the line indicating the sun gear S and the line indicating the carrier C set to "1," and the distance between the line indicating the carrier C and the line indicating the ring gear R set to the gear ratio of the planetary gear mechanism 5 (the ratio of the number of teeth of the sun gear S to the number of teeth of the ring gear R). The position on these three straight lines from a base line perpendicular to these three straight lines indicates the rotation speed of each rotating element.

[0022] In Fig. 2, the diagonal line L indicates the rotational state and torque acting state of each rotating element when the hybrid vehicle 1 is running in a specified state. The torque output by the engine 3 acts on the carrier C in the upward direction in Fig. 2, and the resistance force associated with running the hybrid vehicle 1 acts on the ring gear R in the downward direction in Fig. 2. Then, by applying the torque from the first motor 6 to the sun gear S in the downward direction in Fig. 2, a torque larger than the resistance force associated with running acts on the ring gear R, and this causes the hybrid vehicle 1 to run.

[0023] In the so-called hybrid driving state shown in FIG. 2, the first motor 6 is operated in a direction to reduce its rotation speed, which is a control state in which the first motor 6 functions as a generator. As a result, the electric power obtained by the first motor 6 is charged to the battery 12 or supplied to the second motor 8, and the second motor 8 functions as a motor to output a drive torque. That is, the power output by the engine 3 is divided by the power split mechanism 4 to the output member 7 side and the first motor 6 side, and the so-called direct torque transmitted from the ring gear R to the output member 7 is added to the torque that is converted into electric power by the first motor 6 and the second motor 8 and then converted back into a mechanical torque, and the resulting torque is transmitted to the drive wheels 10. Since the inertial mass of the vehicle body is much larger than the inertial mass of the engine 3, the rotation speed of the engine 3 changes by changing the torque of the first motor 6 from large to small. That is, the engine rotation speed is controlled by the first motor 6.

[0024] The engine 3 is configured so that the throttle opening and the amount of fuel supplied (fuel injection amount) can be electrically controlled as appropriate. That is, the engine 3 is provided with an electronic throttle valve and an injector (not shown) for injecting fuel into the intake port or cylinder, and the output torque can be appropriately controlled by the electronic throttle valve and the injector. Also, as shown in FIG. 2, the engine speed can be continuously and appropriately controlled by the first motor 6. That is, the hybrid vehicle 1 can be operated at an operating point (driving point) with good fuel economy by independently controlling the output torque and the speed of the engine 3. FIG. 3 is a block diagram conceptually showing an example of such control.

[0025] The hybrid vehicle 1, like a normal vehicle, is provided with an acceleration / deceleration operation unit for performing acceleration / deceleration operations such as an accelerator pedal (not shown), and is configured to detect the driving demand amount, which is the operation amount, as an accelerator opening ACC. In addition, like a normal vehicle, the hybrid vehicle 1 is provided with a vehicle speed sensor (not shown). In FIG. 3, the hybrid controller HV-ECU is provided with a required driving force calculation unit 13 that calculates a required driving force F based on the accelerator opening ACC and the vehicle speed V. The required driving force calculation unit 13 has a map with the accelerator opening ACC and the vehicle speed V as parameters (indexes), and calculates the required driving force F from the detected accelerator opening ACC, the vehicle speed V, and the map. The hybrid controller HV-ECU is provided with a running power calculation unit 14 that calculates a running power Pd from the required driving force F and the vehicle speed V obtained in this way. The running power Pd can be calculated as a product of the required driving force F and a predetermined rotation speed according to the vehicle speed V.

[0026] A target rotation speed Net that outputs the running power Pd with optimal fuel efficiency (optimum thermal efficiency) is calculated by a rotation speed calculation unit 15 of the hybrid controller HV-ECU. Specifically, a map is prepared in advance in which an equal power line Lp and an optimal fuel efficiency line Lf are drawn on a coordinate system with the engine torque Te and the rotation speed Ne as parameters (indexes). An example of the map is shown in FIG. 4. The target rotation speed Net is obtained as an intersection of the optimal fuel efficiency line Lf in the map and the equal power line indicating the calculated running power Pd. The engine rotation speed is controlled to a rotation speed that provides optimal fuel efficiency by controlling the rotation speed of the first motor 6 based on the target rotation speed Net. Meanwhile, a target engine torque (target torque) Tet is calculated by a target torque calculation unit 16 in the hybrid controller HV-ECU by dividing the calculated running power Pd by the target rotation speed Net. The throttle opening (and the fuel injection amount) are controlled to achieve the target torque Tet. In this way, the operating point of the engine 3 is controlled to an operating point on the optimum fuel efficiency line Lf, and operation with good fuel efficiency is achieved.

[0027] The hybrid vehicle 1 according to the embodiment of the present invention includes a charge instruction unit (specifically, a charge promotion switch) that starts charging the battery 12 by manual operation. A battery controller (not shown) that controls charging and discharging of the battery 12 controls charging and discharging so that the remaining charge SOC is between an upper limit value and a lower limit value. In addition, even if the remaining charge does not particularly require charging, if the charge promotion switch is manually operated, the power output by the engine 3 is increased to increase the amount of power generated by the first motor 6, for example. Even in this case, the operating point of the engine 3 is set on the above-mentioned optimal fuel efficiency line, but even if the engine 3 is operated at an operating point on the optimal fuel efficiency line, if the fuel efficiency (thermal efficiency) is worsened compared to immediately before the operation due to the charge amount being increased based on a manual operation, the engine 3 is controlled to avoid or suppress the deterioration of fuel efficiency.

[0028] FIG. 5 is a block diagram for explaining the functional configuration of the controller 17 for the control. The controller 17 is an electronic control device mainly composed of a microcomputer, and is configured to perform calculations using input data and pre-stored data, and to output the results of the calculations as a control command signal for controlling the operating state of the engine 3. The main function of the controller 17 is to ensure the remaining charge without deteriorating fuel efficiency when there is a charge promotion request based on an artificial operation, and for this purpose, the controller 17 is configured to first calculate the power (power: kw) that the engine 3 should output. Therefore, the controller 17 is provided with a running power calculation unit 17a that calculates the running power Pd required for the hybrid vehicle 1 to run. As described above with reference to FIG. 3, the running power Pd can be calculated based on the accelerator opening ACC, which is an example of the required driving amount, and the vehicle speed V, and therefore the accelerator opening ACC and the vehicle speed V are input to the controller 17 as detection data.

[0029] As described above, the hybrid vehicle 1 includes the charge prompting switch 18 as a charge instruction unit, and an ON signal generated when the charge prompting switch 18 is manually turned ON is input to the controller 17. The controller 17 includes a total power calculation unit 17b that, upon receiving the ON signal, adds a predetermined charging power to the above-mentioned running power Pd to obtain a total power. Here, the charging power may be a predetermined power such as a maximum power that the engine 3 can output for charging under the running state of the hybrid vehicle at that time or an appropriate constant power that has been determined in advance. Therefore, the controller 17 includes this charging power as pre-stored data.

[0030] Further, a judgment unit 17c is provided for judging whether the total power is out of the range of the thermal efficiency optimum power to the high power side. The thermal efficiency when the engine 3 is operated is best when the operating point (operating point) determined by the engine torque Te and the rotation speed Ne is in a predetermined range determined by the engine torque Te and the rotation speed Ne, and the thermal efficiency decreases (worsens) as the operating point moves away from the range. This is also shown in FIG. 4, and the thermal efficiency (fuel economy) is best in the smallest range on the central side where the contour lines are closed among the range (constant fuel economy region) surrounded by the so-called contour lines connecting the operating points with the same thermal efficiency (fuel economy), and the thermal efficiency gradually decreases in the range surrounded by the contour lines on the outer side. This thermal efficiency range is largely determined by the characteristics of the engine 3, and is determined by experiments, simulations, etc. Therefore, the range ηmax of thermal efficiency optimum power in the embodiment of the present invention is a range that is artificially determined in advance based on experiments or the like, and in FIG. 4, it is the range indicated by the closed curve with the smallest inner area among the concentric contour lines.

[0031] If the engine 3 outputs the power indicated by the isopower line passing through the range ηmax of the thermal efficiency optimum power, the engine 3 can be operated so as to optimize the fuel economy. However, if the engine 3 is operated so as to output the power indicated by the isopower line outside the range ηmax, the fuel economy will be lower than the optimum fuel economy no matter how the operating point is set. Therefore, in the embodiment of the present invention, in order to avoid a decrease (deterioration) in the thermal efficiency (fuel economy) when promoting charging, the determination unit 17c determines whether the total power is such that the operating point can be set in the range ηmax of the thermal efficiency optimum power. Therefore, the controller 17 holds the map shown in FIG. 4 as pre-stored data.

[0032] If the total power is a power indicated by a constant power line that does not cross the range ηmax of the thermal efficiency optimum power, fuel efficiency will deteriorate if charging is performed based on an artificial operation. In this embodiment of the present invention, in order to avoid such a situation, the power required for charging (charging power) is limited. The controller 17 is provided with a charging power limiting unit 17d for calculating the charging power (target charging power) limited in this way. When the charging promotion switch 18 is turned on, a power of a predetermined value is adopted as the charging power. If the total power obtained by adding the charging power to the traveling power Pd is outside the range ηmax of the thermal efficiency optimum power on the high power side, the charging power limiting unit 17d calculates a target charging power by subtracting the power for charging so that the total power falls within the range ηmax of the thermal efficiency optimum power.

[0033] In addition, when the traveling power Pd itself is out of the range ηmax of the thermal efficiency optimum power on the high power side, if the target charging power is calculated so that the total power including the power for charging falls within the range ηmax of the thermal efficiency optimum power, the target charging power will be a negative value. That is, the battery 12 will be discharged. Since the charge promotion switch 18 is turned on in order to increase the state of charge SOC, if the battery 12 is discharged because the target charging power has become a negative value, a situation opposite to the intention of turning on the charge promotion switch 18 will occur. Therefore, in the embodiment of the present invention, the minimum value when calculating the charging power is limited to "0" to avoid discharging.

[0034] The power obtained by adding the target charging power obtained as described above to the traveling power Pd is the vehicle power, and the controller 17 is provided with a vehicle power output unit 17e that outputs this power to, for example, the hybrid controller HV-ECU or an engine controller not shown.

[0035] An example of the control executed by the controller 17 will be described with reference to the flowchart of FIG. 6. The routine shown in FIG. 6 is repeatedly executed at predetermined short intervals, for example, when the hybrid vehicle 1 is running with the engine 3 driven. First, in step S1, a required driving torque (required driving force F) is calculated based on the vehicle speed V and the accelerator opening ACC. Next, a required driving power is calculated based on the required driving torque and the vehicle speed V (step S2). This required driving power corresponds to the running power for the hybrid vehicle 1 to run. Furthermore, in step S3, it is determined whether or not the battery charging mode is set. This battery charging mode is a driving state that is set based on an artificial operation with the intention of increasing the remaining charge SOC of the battery 12, and therefore, in the embodiment described here, it can be determined whether or not the above-mentioned charge promotion switch 18 is turned on and an on signal is input to the controller 17.

[0036] If the result of the determination in step S3 is "YES", a predetermined battery charging mode power is set as the charging power (step S4). The battery charging mode power may be a predetermined constant value, or may be a power equivalent to the maximum charge amount that can be charged at that time.

[0037] In the following step S5, the thermally efficient engine power is calculated. The thermally efficient engine power calculated here is the engine power with the optimal thermal efficiency (fuel economy), i.e., the power indicated by the iso-power line on the highest power side (high load side) among the iso-power lines passing through the range ηmax of the thermally efficient power in Fig. 4. The thermally efficient engine power thus calculated is compared with the total power of the above-mentioned required driving force power and charging power, and it is determined whether the total power is greater than the thermally efficient engine power (step S6).

[0038] If the result of the determination in step S6 is "Yes," operating the engine 3 so as to output the total power would result in the operating point on the optimal fuel consumption line being outside the thermal efficiency optimal power range ηmax, resulting in a deterioration in fuel consumption, so a target charging power is calculated so that the engine 3 can be operated within the thermal efficiency optimal power range ηmax (step S7). Specifically, the target charging power is calculated by subtracting the driving power for traveling (traveling power Pd) from the thermal efficiency optimal engine power.

[0039] The target charging power calculated in this way becomes a positive or negative value depending on the magnitude of the traveling power Pd. Therefore, in step S8, it is determined whether the target charging power calculated in step S7 is a negative value. In other words, it is determined whether the target charging power is smaller than "0". If the determination result in step S6 above is "no", the process immediately proceeds to step S8. In this case, the charging power set in step S4 becomes the target charging power.

[0040] If the result of the determination in step S8 is "NO", when the engine 3 is operated to output the total power of the traveling power Pd and the target charging power, the engine 3 is operated so that the thermal efficiency is optimal (the fuel consumption is minimized) by setting the operating point on the above-mentioned optimal fuel consumption line Lf, and the driving force and charging required for traveling can be secured. Therefore, in this case, the vehicle power is calculated as the sum of the traveling power Pd (driving power) and the target charging power. Then, the process returns.

[0041] On the other hand, if the result of the determination in step S8 is "Yes", the target charging power is set to "0" (step S10). That is, since the target charging power is the power for charging the battery 12, if the value is negative, the battery 12 will be discharged. One example of such a state is a state in which the running power Pd is outside the thermal efficiency optimum power range ηmax on the high power side. Therefore, in order to avoid discharging from the battery 12, if the result of the determination in step S8 is "Yes", the target charging power is set to "0", and then the process proceeds to the above-mentioned step S9 to calculate the vehicle power. In this case, since the target charging power is "0", the vehicle power becomes the running power Pd.

[0042] If the result of the determination in step S3 is "no" because the charge promotion switch 18 has not been turned on, the charge power is calculated based on the control during normal hybrid driving (step S11), and then the process returns. Specifically, the charge power is calculated according to the remaining charge SOC and the drive demand amount. For example, if the remaining charge SOC is smaller than the upper limit and thus charging is possible, and the driving state (driving state) of the hybrid vehicle 1 is in a state in which power is generated by the first motor 6 as shown in FIG. 2, the power generated by the first motor 6 is charged to the battery 12.

[0043] FIG. 7 shows a schematic time chart of the change in vehicle power when the above-mentioned charging power is limited and when it is not limited. In FIG. 7, the dashed line indicates the running power Pd (driving power), which changes in magnitude according to the changes in the vehicle speed V and the accelerator opening ACC. In this state, the charging promotion switch 18 is turned on, so that a predetermined charging power is added to the running power, and the vehicle power is calculated as the sum of these powers. In FIG. 7, the range ηmax of the thermal efficiency optimum power is shown by a dotted line, and in the present invention example, the calculated total power is limited to the upper limit of the range ηmax, and the limited power is output as the vehicle power. In contrast, in the comparative example in which the charging power is not limited according to the present invention, the total power that falls outside the range ηmax of the thermal efficiency optimum power on the high power side is output as the vehicle power. Therefore, according to the present invention example, since the engine 3 is operated in the range ηmax of the thermal efficiency optimum power, charging can be promoted without deteriorating fuel efficiency. In contrast, in the comparative example, although charging can be promoted, the engine 3 is operated outside the range ηmax of the thermal efficiency optimum power, which deteriorates fuel efficiency.

[0044] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the hybrid vehicle targeted by the present invention may be a hybrid vehicle other than a two-motor type. In short, the present invention can be practiced with appropriate modifications within the scope of its gist. [Explanation of symbols]

[0045] 1. Hybrid vehicles 2 Hybrid drivetrain 3 Engine 4 Power split mechanism 5 Planetary gear mechanism 6 First Motor 7 Output member 8 Second Motor 9 Differential Gear 10 Drive wheels 11 Inverter 12 Battery 13 Required driving force calculation unit 14. Running power calculation section 15 Rotational speed calculation section 16 Target torque calculation section 17 Controller 17a Running power calculation section 17b Total power calculation section 17c Judgment section 17d Charging power limiting section 17e Vehicle power output section 18 Charging promotion switch ηmax Thermal efficiency optimum power range ACC Accelerator opening C Carrier F Required driving force HV-ECU Hybrid controller L line Lf Optimum fuel consumption line Lp isopower line Net target speed Ne (engine) revolutions per minute P Pinion gear Pd Running power R ring gear S Sun gear Tet target torque Te engine torque V Vehicle speed

Claims

1. A control device for a hybrid vehicle comprising: an engine; a generator that is driven by a portion of the power output by the engine to generate electricity; a power storage device that is connected to the generator to charge the generator and supply electric power to a motor that outputs a driving force for traveling; and a charge instruction unit that is manually operated to promote the driving of the generator by the engine and the charging of the power storage device from the generator, A controller for controlling an operating state of the engine, The controller: a running power calculation unit for calculating a running power required for the hybrid vehicle to run; a total power calculation unit that, when the charge instruction unit is operated to request promotion of charging of the power storage device, adds a predetermined charging power for the charging to the traveling power to calculate a total power to be output by the engine; A determination unit that determines whether the total power is outside a high power range of a thermal efficiency optimum power range that can make the thermal efficiency a predetermined optimum efficiency; a charging power limiting unit that limits the power for charging to a target charging power that is smaller than the charging power so that the total power falls within the range of the thermal efficiency optimal power when it is determined that the total power is outside the range of the thermal efficiency optimal power to a high power side; A control device for a hybrid vehicle comprising:

2. The control device for a hybrid vehicle according to claim 1, The charging power limiting unit obtains a difference between the thermal efficiency optimum power and the traveling power by subtracting the traveling power from the thermal efficiency optimum power, and sets the target charging power to "0" if the difference is a negative value. A control device for a hybrid vehicle.

3. The control device for a hybrid vehicle according to claim 1 or 2, The thermal efficiency optimum power range is a range that is predetermined based on an equal power line that passes through a predetermined optimum fuel consumption region among equal fuel consumption regions obtained using the output torque and revolution speed of the engine as indexes. A control device for a hybrid vehicle.

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