WO2010122393A2

WO2010122393A2 - Charging system and charging method for hybrid vehicle

Info

Publication number: WO2010122393A2
Application number: PCT/IB2010/000868
Authority: WO
Inventors: Takuichi Arai
Original assignee: Toyota Jidosha Kabushiki Kaisha
Priority date: 2009-04-20
Filing date: 2010-04-19
Publication date: 2010-10-28
Also published as: JP2010247801A; WO2010122393A3

Abstract

A charging system for a plug-in hybrid vehicle equipped with a waste heat utilization device that utilizes the waste heat of an engine to heat the vehicle interior or warm up a catalyst. The charging system charges a battery that supplies electric power to a motor-generator and regenerating an electric power from the motor-generator by means of a charging device when the vehicle is stopped. In the charging system, if it is determined that the waste heat utilization device needs to be operated by starting the engine when the vehicle starts running next time, the charge amount of the battery when the vehicle starts running next time is set by reducing a full-charge charge amount Qfull by a predetermined amount A.

Description

CHARGING SYSTEMAND CHARGING METHOD FOR HYBRID VEHICLE

BACKGROUND OF THE INVENTION

1. Field of the Invention [0001] The invention relates to a charging system and a charging method for a hybrid vehicle to heat the vehicle interior and warm up a catalyst using the waste heat of an internal combustion engine.

2. Description of the Related Art

[0002] It is indispensable to heat a vehicle interior and warm up a catalyst when a vehicle travels in winter or at high latitudes. In general, from the standpoint of effective energy utilization, the waste heat of an engine is utilized for the purpose of heating and the like. In the case of a hybrid vehicle, however, because the engine is stopped while the vehicle is traveling in electric vehicle (EV) mode (i.e., the vehicle is powered exclusively by a motor), the waste heat of the engine cannot be utilized. Thus, the hybrid vehicle is usually equipped with an electric heater. By operating the electric heater, heating may be carried out even when the engine is stopped.

[0003] However, the effects of heating and warm-up are lower if only the electric heater is operated to carry out heating and the like than when the waste heat of the engine is utilized. Thus, no sufficient effect can be obtained when quick heating and the like are required, for example, immediately after the vehicle has started in winter. However, it is also conceivable to mount the vehicle with a high-capacity electric heater to obtain a sufficient heating effect and a sufficient warm-up effect. In this case, however, the consumption of electric power and the cost of production are increased.

[0004] Under such circumstances, there is described in, for example, Japanese Patent Application Publication No. 09-233601 (JP-A-09-233601) an art for starting an engine of a hybrid vehicle during stoppage of the vehicle or EV running as well with a view to ensuring a sufficient heating effect. According to this art, a sufficient heating effect can be obtained even when quick heating is required during stoppage of the vehicle or EV running. [0005] However, according to the aforementioned art described in JP-A-09-233601, the engine is started for the sole purpose of the heating effect. Therefore, when a state of charge (SOC) of a battery is full charge, a motive power of the engine during heating or warm-up cannot be utilized to charge the battery. Thus, there is caused a problem of energy loss. [0006] It should be noted herein that there is a situation in which especially a plug-in hybrid vehicle is often caused to perform EV running over a certain distance from a moment when the vehicle starts running after a battery has been fully charged at home or the like. Thus, the engine is often started with the battery fully charged. As a result, a larger amount of energy loss may be caused.

SUMMARY OF THE INVENTION

[0007] The invention provides a charging system and a charging method for a hybrid vehicle that promote both the heating of a vehicle interior and the warm-up of a catalyst and to reduces the amount of energy loss. [0008] A charging system for a hybrid vehicle according to a first aspect of the invention for a hybrid vehicle equipped with both an internal combustion engine and an electric motor that serve as drive sources of the vehicle; a waste heat utilization device for utilizing a waste heat from the internal combustion engine to at least either heat a vehicle interior or warm up a catalyst; and an accumulation device for supplying an electric power to the electric motor and regenerating an electric power from the electric motor, and charges the accumulation device by means of a charging device during stoppage of the vehicle. The charging system includes a determination means for determining whether the waste heat utilization device needs to be operated by starting the internal combustion engine when the vehicle starts running next time, and charging control means for controlling charging of the accumulation device by the charging device. If the determination means determines that the waste heat utilization device needs to be operated when the vehicle starts running next time, the charging control means sets a charge amount of the accumulation device when the vehicle starts running next time by reducing a full-charge charge amount by a predetermined amount. [0009] The charging system according to the foregoing first aspect of the invention is applied to the hybrid vehicle equipped with the waste heat utilization device for utilizing the waste heat of the internal combustion engine at least either to heat the vehicle interior or to warm up the catalyst. The charging device then charges the accumulation device provided in the vehicle during stoppage of the vehicle. The charging control means controls the charging of the accumulation device by this charging device. Further, in this charging system, the determination means determines whether the waste heat utilization device needs to be operated by starting the internal combustion engine when the vehicle starts running next time. When the determination means determines that the waste heat utilization device needs to be operated when the vehicle starts running next time, the charging control means then sets the charge amount of the accumulation device when the vehicle starts running next time by reducing the full-charge charge amount by the predetermined amount. Thus, the accumulation device can be rendered chargeable. Therefore, even when the internal combustion engine is started when the vehicle starts running next time, the accumulation device can be reliably charged. As a result, it is possible both to promote the heating of the vehicle interior and the warm-up of the catalyst with the aid of the waste heat of the internal combustion engine and to reduce the amount of energy loss.

[0010] In the charging system according to the foregoing first aspect of the invention, the hybrid vehicle may be a plug-in hybrid vehicle.

[0011] In the charging system according to the foregoing first aspect of the invention, the predetermined amount may be determined on a basis of a difference between a charge amount of the accumulation device and a discharge amount of the accumulation device from a moment when the vehicle starts running according to a prescribed vehicle running pattern to a moment when a temperature of the vehicle interior reaches a predetermined temperature in a case where the waste heat of the internal combustion engine is utilized to heat the vehicle interior.

[0012] In the charging system according to the foregoing first aspect of the invention, the predetermined amount may be determined on a basis of a difference between a charge amount of the accumulation device and a discharge amount of the accumulation device from a moment when the vehicle starts running according to a prescribed vehicle travel pattern to a moment when a temperature of the catalyst reaches a predetermined temperature in a case where the waste heat of the internal combustion engine is utilized to warm up the catalyst.

[0013] According to the foregoing first aspect of the invention, the predetermined amount is determined as described above. The amount of an electric power with which the accumulation device can be charged during the actual running of the vehicle can thereby be appropriately predicted to appropriately charge the accumulation device. As a result, the accumulation device can be charged without incurring waste with the aid of a motive power of the internal combustion engine when the vehicle starts running next time. Therefore, the amount of energy loss can be more reliably reduced.

[0014] In the meantime, a generalization cannot be made due to the fact that the amount of the waste heat of the internal combustion engine, the capacity of heating or warm-up, the thermal capacity of the vehicle interior, and the like differ depending on the type of the vehicle. However, the motive power of the internal combustion engine during the start thereof in a conventional vehicle makes it possible to ensure at least about 5% of the full-charge charge amount of the accumulation device. On the other hand, the charge amount of the accumulation device at the moment when the vehicle starts running needs to be at least about 80% of the full-charge charge amount in order to enable stable EV running from the moment when the vehicle starts running. Thus, stable EV running from the moment when the vehicle starts running is considered to be made possible by setting the amount of the electric power with which the .accumulation device can be charged to at most about 20% of the full-charge charge amount.

[0015] Thus, in the charging system according to the foregoing first aspect of the invention, the predetermined amount may be within a range of 5 to 20% of a full-charge charge amount of the accumulation device.

[0016] According to the foregoing first aspect of the invention, the predetermined amount is set within the range of 5 to 20%. A minimum charge amount at the moment when the vehicle starts running can thereby be ensured. Further, even if the determination means makes an erroneous determination, the vehicle can perform stable EV running. That is, even when the determination means determines that the waste heat utilization device needs to be operated by starting the internal combustion engine when the vehicle starts running next time and the internal combustion engine is not started due to a lack of the necessity to operate the waste heat utilization device at the moment when the vehicle starts running although the accumulation device has not been fully charged, the vehicle can perform stable EV running over a predetermined distance.

[0017] In the meantime, the motive power of the internal combustion engine differs depending on the displacement of the internal combustion engine. Accordingly, the charge amount of the accumulation device obtained with the aid of the motive power of the internal combustion engine differs depending on the displacement of the internal combustion engine.

[0018] Thus, in the charging system according to the foregoing first aspect of the invention, the predetermined amount may be within a range of 0.3 to 7 kWh, in consideration of differences in displacement among conventional internal combustion engines. [0019] According to the foregoing first aspect of the invention, the predetermined amount is set within the range of 0.3 to 7 kWh. The motive power of the internal combustion engine can thereby be effectively utilized without incurring waste to charge the accumulation device regardless of differences in displacement among internal combustion engines. [0020] The charging system according to the foregoing first aspect of the invention may further be equipped with travel history storage means for storing a travel history of the vehicle. The determination means may make the determination with an aid of the travel history stored in the travel history storage means.

[0021] According to the foregoing first aspect of the invention, the determination means makes the determination with the aid of the travel history of the vehicle as described above. The determination can thereby be made with higher accuracy reflecting the travel history of the vehicle. As a result, the charging of the accumulation device can be appropriately controlled by the charging control means to more reliably reduce the amount of energy loss. [0022] The charging system according to the foregoing first aspect of the invention may further be equipped with waste heat utilization history storage means for storing a waste heat utilization history of the waste heat utilization device. The determination means may make the determination with an aid of the waste heat utilization history stored in the waste heat utilization history storage means.

[0023] According to the foregoing first aspect of the invention, the determination means makes the determination with the aid of the waste heat utilization history of the waste heat utilization device as described above. The determination can thereby be made with higher accuracy reflecting the waste heat utilization history. As a result, the charging of the accumulation device can be appropriately controlled by the charging control means to more reliably reduce the amount of energy loss.

[0024] The charging system according to the foregoing first aspect of the invention may further be equipped with ambient air temperature history storage means for storing an ambient air temperature history. The determination means may make the determination with an aid of the ambient air temperature history stored in the ambient air temperature history storage means.

[0025] According to the foregoing first aspect of the invention, the determination means makes the determination with the aid of the ambient air temperature history as described above. The determination can thereby be made with higher accuracy reflecting the ambient air temperature history. As a result, the charging of the accumulation device can be appropriately controlled by the charging control means to more reliably reduce the amount of energy loss.

[0026] The charging system according to the foregoing first aspect of the invention may further be equipped with input information storage means for storing information input from a user of the vehicle. The determination means may make the determination with an aid of the input information stored in the input information storage means.

[0027] According to the foregoing first aspect of the invention, the determination means makes the determination with the aid of the information input from the user as described above. The determination can thereby be made reflecting an intention of the user (e.g., priority given to heating and warm-up, priority given to EV running, or the like).

[0028] A charging method for a hybrid vehicle according to a second aspect of the invention for a hybrid vehicle equipped with both an internal combustion engine and an electric motor that serve as drive sources of the vehicle; a waste heat utilization device for

« utilizing a waste heat from the internal combustion engine to at least either heat a vehicle interior or warm up a catalyst; and an accumulation device for supplying an electric power to the electric motor and regenerating an electric power from the electric motor, and charges the accumulation device by means of a charging device during stoppage of the vehicle. The charging method includes determining whether the waste heat utilization device needs to be operated by starting the internal combustion engine at a moment when the vehicle starts running next time, and controlling charging of the accumulation device by the charging device so that a charge amount of the accumulation device when the vehicle starts running next time is set by reducing a full-charge charge amount by a predetermined amount when it is determined that the waste heat utilization device needs to be operated when the vehicle starts running next time.

[0029] According to the charging method for the hybrid vehicle according to the foregoing second aspect of the invention, an effect similar to that of the charging system for the hybrid vehicle according to the foregoing first aspect of the invention can be obtained. [0030] The charging system and the charging method according to the foregoing aspects of the invention make it possible both to promote the heating of the vehicle interior and the warm-up of the catalyst and to reduce the amount of energy loss.

BRIEF DESCRIPTION OF THE DRAWINGS [0031] The foregoing and/or further objects, features and advantages of the invention will become more apparent from the following description of an example embodiment with reference to the accompanying drawings, in which like numerals are used to represent like elements and wherein:

FIG. 1 is a block diagram showing the entire configuration of a charging system according to the embodiment of the invention;

FIG. 2 is a graph showing running patterns of the charging system according io the embodiment of the invention in a 10-mode and a 15-mode; and

FIG 3 is a flowchart showing the contents of control executed by a charging control device of the charging system according to the embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENT

[0032] The embodiment of the invention as a concretization of a charging system for a hybrid vehicle according to the invention will be described hereinafter in detail with reference to the drawings.

[0033] A plug-in hybrid vehicle that is charged using the charging system according to this embodiment of the invention will be described with reference to FIG. 1. FIG. 1 is a block diagram showing the overall configuration of the charging system according to the embodiment of the invention. [0034] As shown in FIG. 1, a plug-in hybrid vehicle 20 (hereinafter sometimes referred to simply as "the vehicle 20") according to a charging system 10 includes an engine

21 and a motor-generator 22 as motive power sources of the vehicle; a waste heat utilization device 23 that utilizes heat generated by the engine 21 to heat the vehicle interior and warm up a catalyst; a waste heat utilization history storage device 26 that stores the waste heat utilization history of the waste heat utilization device 23; an battery 25 that supplies electric power to the motor-generator 22 or regenerating an electric power from the motor-generator 22; an inverter device 24 that controls the charging/discharging between the motor-generator

22 and the battery 25; a navigation system 27 that stores the travel history of the vehicle; an engine ECU 28 that controls the operation of the engine 21; and an HV-ECU 29 that controls the operation of the inverter device.

[0035] The engine 21 is connected to the engine ECU 28. The motor-generator 22 and the battery 25 are connected to each other via the inverter 24. The inverter device 24 includes a converter and an inverter for electric power conversion, and is connected to the HV-ECU 29. Then, the motor-generator 22 and the inverter, the inverter and the converter, and the converter and the battery 25 are connected to each other respectively. The number of motor-generators 22 installed may be adjusted as appropriate. Further, a motor connected to driving wheels of the vehicle and a generator connected to a crankshaft of the engine 21 may be arranged separately from each other. In the embodiment of the invention, the engine 21 according is an example of "the internal combustion engine" of the invention, the motor-generator 22 is an example of "the electric motor" of the invention, and the battery 25 is an example of "the accumulation device" of the invention.

[0036] The waste heat utilization device 23 heats the vehicle interior and warms up the catalyst using heat obtained from the coolant used to cool the engine 21. More specifically, the waste heat utilization device 23 introduces to the vehicle interior and the vicinity of the catalyst the coolant that has absorbed a waste heat of the engine 21 and risen in temperature, thereby heating the vehicle interior and warming up the catalyst. Accordingly, the waste heat utilization device 23 operates as the engine 21 is driven. It should be noted that this waste heat utilization device 23 may serve only to heat the vehicle interior or only to warm up the catalyst.

[0037] The waste heat utilization history storage device 26 includes storage elements such as a random access memory (a RAM) and the like, and stores the operating time of the waste heat utilization device 23 (a driving time of the engine 21), the temperature of the coolant utilized for heating and warm-up, and the like as a waste heat utilization history. It should be noted that the waste heat utilization history storage device 26 according to this embodiment is an example of "the waste heat utilization history storage means" of the invention.

[0038] The navigation system 27 includes a conventional GPS function and the like, and detects and stores the travel route of the vehicle 20, a travel time of the vehicle 20, and the like as a travel history. It should be noted that the navigation system 27 according to this embodiment is an example of "the travel history storage device" of the invention.

[0039] Each of the engine ECU 28 and the HV-ECU 29 includes a microcomputer that electronically controls various peripheral components. The microcomputer includes a central processing unit (a CPU), a random access memory (a RAM), a read only memory (a ROM), and the like, and processes the signals received by each of the ECU's 28 and 29. Further, the engine ECU 28 exchanges signals with the HV-ECU 29 in controlling the operations of the engine 21 and the inverter device 24 based on a required torque, a charge amount of the battery 25, and the like, while exchanging signals with each other. [0040] Examples of the contents of the control executed by the engine ECU 28 and the HV-ECU 29 installed in the plug-in hybrid vehicle 20 according to this embodiment of the invention will now be described briefly when (1) the vehicle is stopped, (2) the vehicle is accelerating, and (3) the vehicle is decelerating. In the following cases (1) to (3), priority is given to the heating of the vehicle interior and the warm-up of the catalyst regardless of fuel consumption in each running state. The cases (1) to (3) may be arbitrarily selected or combined with one another.

[0041] First of all, the example during stoppage of the vehicle (case (I)) will be described. In this example, the engine ECU 28 controls the engine 21 to continue running even when the vehicle 20 is stopped at a traffic light or the like. Because the engine 21 continues to run, the waste heat utilization device 23 operates to heat the vehicle interior and warm up the catalyst. At this moment, the HV-ECU 29 actuates the inverter device 24 to charge the battery 25 with an electric power generated by the motor-generator 22 with the aid of a motive power of the engine 21. In this case, an engine rotational speed corresponding to the best fuel consumption efficiency and the best charging efficiency in charging the battery 25 during stoppage of the vehicle (during idling) can be exemplified as about 1200 to 1400 rpm when the vehicle starts running at low ambient air temperatures (e.g., -20 to -10 ⁰C). The engine rotational speed may also be regarded as an optimal engine rotational speed when priority is given to the heating of the vehicle interior and the warm-up of the catalyst when the vehicle is driven. [0042] Next, the example during acceleration of the vehicle (case (2)) will be described. In this example, the engine ECU 28 drives the engine 21 as a motive power source of the vehicle 20 when the vehicle is accelerating. Simultaneously, the HV-ECU 29 also actuates the inverter device 24 under certain circumstances to drive the motor-generator 22 as a motive power source of the vehicle 20. It should be noted that the HV-ECU 29 actuates the inverter device 24 under certain circumstances to charge the battery 25 with the electric power generated by the motor-generator 22 with the aid of a surplus motive power of the engine 21 when the vehicle 20 is accelerated by driving only the engine 21.

[0043] Finally, the example during deceleration of the vehicle (case (3)) will be described. In this example, the engine ECU 28 continues to drive the engine 21 during deceleration of the vehicle as well. During the deceleration, the HV-ECU 29 actuates the inverter device 24 to charge the battery 25 with the electric power generated by the motor-generator 22 with the aid of the motive power of the engine 21.

[0044] Next, a charging installation for charging the plug-in hybrid vehicle 20 having the aforementioned configuration will be described. The charging installation may be installed, for example, at home or the like to charge the battery 25 provided in the vehicle 20 during stoppage of the vehicle. The charging installation includes a charging device 11 that supplies electric power to the battery 25 provided in the vehicle 20, a charging control device 12 that controls the charging of the battery 25 by the charging device 11, a thermometer 13 that detects the ambient air temperature, and an input device 14 that allows a user of the vehicle 20 to input.

[0045] The charging device 11 may be connected to a domestic power supply or the like, and includes a plug that may be inserted into the plug-in hybrid vehicle 20. The charging device 11 is connected to and controlled by the charging control device 12 to be controlled through a drive signal of the charging control device 12.

[0046] The input device 14 may include a panel that may be operated by user, and stores a command to give priority to heating and warm-up, a designation of a charge amount, and the like as information input by the user of the vehicle 20. The information input to and stored in the input device 14 are transmitted to the charging control device 12. The input device 14 according to this embodiment is an example of "the input information storage means" of the invention. Further, the thermometer 13 is connected to the charging control device 12. The ambient air temperature detected by the thermometer 13 is then transmitted to the charging control device 12. It should be noted that the thermometer 13 and the input device 14 are not necessarily installed at home or the like, but may be installed in, for example, the plug-in hybrid vehicle 20 itself.

[0047] As is the case with the engine ECU 28 and the HV-ECU 29, the charging control device 12 includes a microcomputer and may process received input signalsd the like. Further, the charging control device 12 acquires the waste heat utilization history stored in the waste heat utilization history storage device 26 and the travel history stored in the navigation system 27 when the plug-in hybrid vehicle 20 is stopped or the plug of the charging device 11 is inserted. Before starting to charge the battery 25, the charging control device 12 according to this embodiment of the invention determines whether the waste heat utilization device 23 needs to be operated by starting the engine 21 at a moment when the vehicle 20 starts running next time. Then, if it is determined that the waste heat utilization device 23 needs to be operated at the moment when the vehicle 20 starts running next time, the charging control device 12 sets the charge amount of the battery 25 at the moment when the vehicle 20 starts running next time by reducing a full-charge charge amount Qfull by a predetermined amount A. In contrast, if it is determined that the waste heat utilization device 23 does not need to be operated at the moment when the vehicle 20 starts running next time, the charging control device 12 sets the charge amount of the battery 25 at the moment when the vehicle 20 starts running next time to the full-charge charge amount Qfull. It should be noted that the charging control device 12 according to this embodiment is an example of "the charging control means" of the invention and "the determination means" of the invention. An example of a determination made by the charging control device 12, the calculation of the predetermined amount A, and the contents of the control of the charging device 11 will be described below in detail.

[0048] First, the example of the above determination made by the charging control device 12 will be described. In this example, the charging, control device 12 makes the determination based on the travel history of the vehicle, the aforementioned waste heat utilization history, the ambient air temperature history, the aforementioned pieces of the input information, and the like. More specifically, when utilizing the travel history, the charging control device 12 sets in advance criteria, for example, a longitude and altitude of a running area, the travel time, and the like, and makes the determination depending on whether the set criteria are satisfied. When utilizing the waste heat utilization history, the charging control device 12 makes the determination depending on, for example, whether the waste heat utilization device 23 was driven when the vehicle 20 started running last time. When utilizing the ambient air temperature history, the charging control device 12 sets in advance, for example, threshold values of the ambient air temperature at the moment when the vehicle 20 starts running and makes the determination depending on whether the set criteria are satisfied. When utilizing the pieces of the input information, the charging control device 12 assigns higher priority to the pieces of the input information than to other pieces of information, and makes the determination in accordance with a command to prioritize heating and warm-up and a designation of a charge amount as input by the user. It should be noted that the charging control device 12 may combine the respective pieces of the information with one another or select a required one or required ones information from of the respective pieces of the information received to make the determination.

[0049] As in this example, if the charging control device 12 utilizes the pieces of the information input by the user to make the determination, it is possible to make a determination reflecting an intention of the user (e.g., priority given to heating and warm-up, priority given to EV running, or the like). Further, when the charging control device 12 utilizes the travel history, the waste heat utilization history, and the ambient air temperature history in making the determination, it is possible to make a more accurate determination with higher accuracy reflecting the running history, the waste heat utilization history, and the outside air temperature history. As a result, the amount of energy loss may be more reliably reduced by appropriately controlling the charging of the battery 25 by the charging device 11 through the use of the charging control device 12.

[0050] Next, an example of the calculation of the predetermined amount A will be described. The predetermined amount A is calculated based on a difference between a charge amount of the battery 25 and a discharge amount of the battery 25 from when the vehicle starts traveling according to a prescribed travel pattern to when the temperature of the vehicle interior or the temperature of the catalyst reaches a predetermined temperature.

[0051] An example of a method of calculating the predetermined amount A in the case where running patterns in a 10 mode and a 15 mode are utilized with a predetermined temperature of 20 ⁰C will now be described with reference to FIG. 2. FIG. 2 is a graph showing the running patterns in the 10 mode and the 15 mode. As shown in FIG. 2, according to the running patterns in the 10 mode and the 15 mode, the vehicle is stopped, accelerated, and decelerated a plurality of times. In this case, charging and discharging are carried out a plurality of times between the motor-generator 22 and the battery 25. It is assumed herein that the vehicle starts traveling in the 10 mode and the 15 mode with the ambient air temperature and the temperature of the battery equal to -5 °C and 0 ⁰C respectively, and that the temperature of the vehicle interior reaches 20 °C after 660 seconds has elapsed from when the vehicle starts traveling. First, the difference between a charge amount of the battery 25 regenerated during the 660 seconds and the amount of electric power discharged from the battery 25 as an amount of the electric power discharged to the motor-generator 22 is calculated. A percentage ratio of the electric power amount equivalent to this difference to the full-charge charge amount Qfull of the battery 25 is then calculated. The calculated ratio is then multiplied by a safety factor to be calculated as the predetermined amount A.

[0052] By thus determining the predetermined amount A, it is possible to appropriately predict the amount of the electric power with which the battery 25 may be charged during the actual travel of the vehicle and hence charge the battery 25 appropriately. As a result, the battery 25 may be charged without incurring waste using the motive power of the engine 21 when the vehicle 20 starts running next time, and the amount of energy loss may be reduced more reliably.

[0053] However, a generalization cannot be made due to the fact that the amount of the waste heat of the engine 21, the capacity of heating or warm-up, the thermal capacity of the vehicle interior, and the like differ depending on the type of the vehicle. Generally, though, the motive power of the engine 21 when started in a conventional vehicle makes it possible to ensure at least about 5% of the full-charge charge amount Qfull of the battery 25. In contrast, the charge amount of the battery 25 when the vehicle 20 starts running needs to be at least about 80% of the full-charge charge amount Qfull in order to enable stable operation in EV mode running from the moment when the vehicle 20 starts running. Thus, stable EV operation from the moment when the vehicle starts running may be enabled by setting the amount of the electric power with which the battery 25 can be charged to at most about 20% of the full-charge charge amount Qfull. [0054] Accordingly, the predetermined amount A may be set within a range of 5 to

20% of the full-charge charge amount Qfull of the battery 25. By setting the predetermined amount A within this range, a minimum charge amount at the moment when the vehicle 20 starts running can be ensured. Further, even if the charging control device 12 makes an erroneous determination, the vehicle 20 can perform stable EV running. That is, even if the charging control device 12 determines that the waste heat utilization device 23 needs to be operated by starting the engine 21 when the vehicle 20 starts running next time and the engine 21 is not started because it is not necessary to operate the waste heat utilization device 23 when the vehicle 20 starts moving although the battery 25 has not been fully charged, the vehicle 20 may stably operate in EV mode over a predetermined distance. [0055] The motive power of the engine 21 differs depending on the displacement of the engine 21. Accordingly, the charge amount of the battery 25 obtained with the aid of the motive power of the engine 21 differs depending on the displacement of the engine 21.

[0056] Thus, as another mode of calculating the predetermined amount A, a calculation example taking into account general differences in the displacement of the engine 21 will be described. For example, if the displacement of the engine 21 is within a range of 1500 to 3000 cc, an output of about 3 to 20 kW is obtained when the engine rotational speed is more or less 1300 rpm. However, the time required until the temperature of the vehicle interior to 20 ⁰C while maintaining an idling state from the moment when the vehicle 20 starts running is about 5 to 20 minutes. Accordingly, if an output of 3 kW (corresponding to the displacement of 1500 cc) is entirely utilized to charge the battery 25, the assembled battery 25 can be charged with an electric power of 0.3 kWh in 5 minutes. However, if an output of 20 kW (corresponding to the displacement of 3000 cc) is entirely utilized to charge the battery 25, the assembled battery 25 can be charged with an electric power of about 7 kWh in 20 minutes. [0057] As is apparent from the above, the range of the predetermined amount A may be calculated as the range of 0.3 to 7 kWh. By setting the predetermined amount A within this range, the motive power of the engine 21 is effectively utilized without incurring waste to charge the battery 25 regardless of the displacement of the engine 21. It should be noted that' this calculation mode is also applicable to a case where the vehicle is running. [0058] Next, the contents of the control executed by the charging control device

12 in the charging system 10 configured as described above will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the contents of the control executed by the charging control device of this charging system.

[0059] As shown in FIG. 3, in step S31, the charging control device 12 detects connection of a charging plug. More specifically, the charging control device 12 detects that the user of the vehicle 20 has inserted the charging plug of the charging device 11 into the vehicle 20. The charging control device 12 then proceeds to step S32.

[0060] In step S32, the charging control device 12 causes the charging device 11 to start charging the battery 25. The charging control device 12 then proceeds to step S33. [0061] In step S33, the charging control device 12 determines whether the state of charge SOC of the battery 25 has reached "Qfull-A". If the result of this determination is affirmative (S33: YES), the charging control device 12 proceeds to step S34. However, if the result of this determination is negative (S33: NO), the charging control device 12 does not proceed to the subsequent step until the state of charge SOC reaches "Qfull-A". That is, the charging device 11 continues to charge the battery 25.

[0062] In step S34, the charging control device 12 determines whether heating and warm-up are required when the vehicle 20 starts running next time. If it is determined that heating and warm-up are required (S34: YES), the charging control device 12 proceeds to step S36. However, if it is determined that heating and warm-up are not required (S34: NO), the charging control device 12 proceeds to step S35. It should be noted that the charging control device 12 may be caused to shift the processing to step S36 if it is determined that at least one of heating or warm-up is required, and that the charging control device 12 may be caused to shift the processing to step S35 if it is determined that neither heating nor warm-up is required. [0063] In step S35, the charging control device 12 determines whether the state of charge SOC has reached the full-charge charge amount Qfull. If the result of this determination is affirmative (S35: YES), the charging control device 12 proceeds to step S36. In contrast, if the result of this determination is negative (S35: NO), the charging control device 12 does not proceed to the next step until the state of charge SOC reaches the full-charge charge amount Qfull. That is, the charging device 11 continues to charge the battery 25.

[0064] In step S36, the charging control device 12 terminates the charging of the battery 25 by the charging device 11. As described above, the charging of the plug-in hybrid vehicle 20 is completed.

[0065] Then, in the plug-in hybrid vehicle 20 that has been charged, the engine ECU 28 drives the engine 21 in heating the vehicle interior and warming up the catalyst at the moment when the vehicle 20 starts running next time. In response to the driving of the engine 21, the waste heat utilization device 23 operates to heat the vehicle interior and warm up the catalyst. The HV-ECU 29 then actuates the inverter device 24 to charge the battery 25 with the aid of the motive power of the engine 21. In this case, in the charging system 10, if it is determined that the waste heat utilization device 23 needs to be operated when the vehicle 20 starts running next time, the charging control device 12 sets the charge amount of the battery 25 when the vehicle 20 starts running next time by reducing the full-charge charge amount Qfull by the predetermined amount A. Thus, the battery 25 can be rendered chargeable. Therefore, the battery 25 may be reliably charged even if the engine 21 is started when the vehicle 20 starts running next time.

[0066] As described in detail above, in the charging system 10 according to the embodiment of the invention, the waste heat utilization device 23 effectively leverages the waste heat of the engine 21 to heat the vehicle interior and the warm-up the catalyst. Further, the charging control device 12 appropriately controls the state of charge SOC of the battery 25 when the vehicle 20 starts traveling next time, and the motive power of the engine 21 started at the moment when the vehicle 20 starts running next time is effectively utilized to charge the battery 25. As a result, the heating of the vehicle interior and the warm-up of the catalyst with the aid of the waste heat of the engine 21 are promoted effectively while reducing the amount of energy loss.

[0067] It should be noted that the above embodiment of the invention is merely an example and is not meant to limit the invention. Various improvements and modifications to the embodiment are possible without departing from the scope of the invention.

[0068] For example, the plug-in hybrid vehicle 20 according to the embodiment of the invention may be provided with an electric heater separately from the waste heat utilization device 23 to make it possible to heat the vehicle interior and warm up the catalyst in a supplementary manner. [0069] While the invention has been described with reference to an example embodiment thereof, it should be understood that the invention is not restricted to the described embodiment. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the example embodiment are shown in various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the spirit and scope of the invention.

Claims

1. A charging system for a hybrid vehicle equipped with both an internal combustion engine and an electric motor that serve as drive sources of the vehicle; a waste heat utilization device for utilizing a waste heat from the internal combustion engine to at least either heat a vehicle interior or warm up a catalyst; and an accumulation device for supplying an electric power to the electric motor and regenerating an electric power from the electric motor, and which charges the accumulation device by means of a charging device during stoppage of the vehicle, the charging system characterized by comprising: determination means for determining whether the waste heat utilization device needs to be operated by starting the internal combustion engine when the vehicle starts running next time; and charging control means for controlling charging of the accumulation device by the charging device, wherein the charging control means sets a charge amount of the accumulation device when the vehicle starts running next time by reducing a full-charge charge amount by a predetermined amount when the determination means determines that the waste heat utilization device needs to be operated when the vehicle starts running next time.

2. The charging system according to claim 1, wherein the hybrid vehicle is a plug-in hybrid vehicle.

3. The charging system according to claim 1 or 2, wherein the predetermined amount is determined on a basis of a difference between a charge amount of the accumulation device and a discharge amount of the accumulation device from a moment when the vehicle starts running according to a prescribed vehicle running pattern to a moment when a temperature of the vehicle interior reaches a predetermined temperature in a case where the waste heat of the internal combustion engine is utilized to heat the vehicle interior.

4. The charging system according to claim 1 or 2, wherein the predetermined amount is determined on a basis of a difference between a charge amount of the accumulation device and a discharge amount of the accumulation device from a moment when the vehicle starts running according to a prescribed vehicle travel pattern to a moment when a temperature of the catalyst reaches a predetermined temperature in a case where the waste heat of the internal combustion engine is utilized to warm up the catalyst.

5. The charging system according to any one of claims 1 to 4, wherein the predetermined amount is within a range of 5 to 20% of a full-charge charge amount of the accumulation device.

6. The charging system according to any one of claims 1 to 4, wherein the predetermined amount is within a range of 0.3 to 7 kWh.

7. The charging system according to any one of claims 1 to 6, further comprising: travel history storage means for storing a travel history of the vehicle, wherein the determination means makes the determination with an aid of the travel history stored in the travel history storage means.

8. The charging system according to any one of claims 1 to 7, further comprising: waste heat utilization history storage means for storing a waste heat utilization history of the waste heat utilization device, wherein the determination means makes the determination with an aid of the waste heat utilization history stored in the waste heat utilization history storage means.

9. The charging system according to any one of claims 1 to 8, further comprising: ambient air temperature history storage means for storing an ambient air temperature history, wherein the determination means makes the determination with an aid of the ambient air temperature history stored in the ambient air temperature history storage means.

10. The charging system according to any one of claims 1 to 9, further comprising: input information storage means for storing information input from a user of the vehicle, wherein the determination means makes the determination with an aid of the input information stored in the input information storage means.

11. A charging method for a hybrid vehicle equipped with both an internal combustion engine and an electric motor that serve as drive sources of the vehicle; a waste heat utilization device for utilizing a waste heat from the internal combustion engine to at least either heat a vehicle interior or warm up a catalyst; and an accumulation device for supplying an electric power to the electric motor and regenerating an electric power from the electric motor, and which charges the accumulation device by means of a charging device during stoppage of the vehicle, the method characterized by comprising: determining whether the waste heat utilization device needs to be operated by starting the internal combustion engine at a moment when the vehicle starts running next time; and controlling charging of the accumulation device by the charging device so that a charge amount of the accumulation device when the vehicle starts running next time is set by reducing a full-charge charge amount by a predetermined amount when it is determined that the waste heat utilization device needs to be operated when the vehicle starts running next time.