JP2011230671A - Power generation control device of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To promptly recover the electricity storage amount while preferentially performing efficient power generation in power generation using engine drive force of a hybrid vehicle which uses an engine and a motor as a source of driving force.SOLUTION: In the hybrid vehicle which uses the engine and the motor as a source of driving force, when an electric storage device is in a predetermined charging required state, power generation is performed by using the surplus part of the engine drive force when the gas pedal is ON. In this case, according to the difference of the target electricity storage amount and the actual electricity storage amount, and time change of the difference, the value of power generation permission lower limit efficiency which is a threshold to permit power generation is changed (S506), and power generation at efficiency below power generation permission lower limit efficiency is forbidden (S512). Thereby recovery of the electricity storage amount is promptly enabled without lapsing into shortage of the electricity storage amount, while preferentially performing efficient power generation in any traveling conditions.

Description

  The present invention relates to a power generation control device for a hybrid vehicle.

  In consideration of the global environment, the development of hybrid vehicles equipped with engines and motors as driving force sources is underway. Hybrid vehicles achieve low fuel consumption and reduce greenhouse gas emissions by driving the motor in the low-efficiency operation region of the engine, high-efficiency operation of the engine, and recovery of braking energy.

  As an opportunity for charging a battery in a hybrid vehicle, in addition to energy regeneration during deceleration, there is power generation using the remaining driving power of the engine (hereinafter referred to as power generation traveling). In power generation traveling, torque equal to or higher than the driving torque required by the driver is output by the engine, and the surplus of engine torque corresponding to the driving surplus power shown in FIG. 1 is used for power generation in the motor.

  Examples of operating points (rotation speed, torque) of the engine and motor during power generation traveling are shown in FIGS. In both figures, the isoefficiency lines are shown for each of the engine and motor. Here, the engine efficiency is the proportion of the calorific value of gasoline that can be output as power in the engine shaft, and the motor efficiency (power generation side) is the rotational energy given to the motor shaft from the outside. It is the ratio that can be stored as electric power. Points P1 and Q1 in the figure are operating points of the engine and the motor when power generation is not performed. When power generation is performed, the operating point moves to points P2 and Q2. In general, the operating point of the engine during power generation running is set near the torque at which high-efficiency operation is possible, and the magnitude of torque (hereinafter referred to as power generation torque) used for power generation is determined by the difference from the torque required for running . The broken line in FIG. 2 is a line connecting operating points at which the maximum efficiency operation can be performed at each rotation speed (hereinafter referred to as a fuel efficiency optimum line). It is known that the engine operating point during power generation traveling is set near the fuel efficiency optimum line (see, for example, Patent Document 1).

  The engine and motor operating points in a parallel hybrid vehicle are related to driving conditions (vehicle speed / load). The power generation efficiency (product of engine efficiency and motor efficiency) during power generation travel depends on the engine and motor speed determined by the vehicle speed and the magnitude of the power generation torque, so in actual travel where various travel conditions are mixed, Highly efficient power generation is not always possible. In addition, from the viewpoint of efficient energy management, the amount of power stored in the battery must be controlled within an appropriate range that is neither overcharged nor overdischarged. When the battery needs to be charged, It is desirable to recover quickly to the amount.

  In order to improve the energy efficiency, it is necessary to quickly recover the amount of charge stored in the battery while selectively performing highly efficient power generation. The navigation information is acquired when the power storage device is in a predetermined state that requires charging. If it is predicted that the high-efficiency driving condition will be satisfied in the near future instead of the high-efficiency driving condition where the engine can be operated efficiently, the power storage device will be charged after the high-efficiency driving condition is reached. In addition, an automobile control method for prohibiting current power generation is known (see, for example, Patent Document 2).

JP 2004-144041 A JP 2008-94233 A

  According to the inventions disclosed in Patent Documents 1 and 2, in the power generation using the engine driving force of the hybrid vehicle using the engine and the motor as the driving force source, the highly efficient power generation is preferentially performed and the storage amount is quickly increased. Therefore, there is a problem that flexible control according to the amount of power stored in the battery is not possible.

  The power generation control device according to claim 1 is a power generation control device that is mounted on a hybrid vehicle and controls power generation by a motor for charging a battery in accordance with power generation torque generated by an engine. Calculates the required driving torque required for driving the hybrid vehicle based on the accelerator opening, and calculates the power generation torque based on the vehicle speed and the required driving torque, and based on the vehicle speed, the required driving torque, and the power generating torque. , Physical quantity calculating means for calculating the physical quantity related to the charging efficiency of the battery according to the power generation torque, charge amount calculating means for calculating the charging quantity necessary for charging the battery, and prohibiting power generation when the physical quantity falls below a predetermined lower limit value When the power generation prohibition means to perform and the rate of change of the stored amount of the battery with respect to time are not included in the first predetermined range, the predetermined lower limit value And a correction correcting means, the predetermined lower limit value, characterized in that the larger the amount of charge required small.

  According to the present invention, high-efficiency power generation is preferentially performed according to the amount of electricity stored in the battery, and the amount of electricity stored can be quickly recovered.

It is a figure showing the torque distribution at the time of electric power generation driving | running | working. It is a figure showing the electric power generation torque at the time of electric power generation driving | running | working, and an engine operating point change. It is a figure showing the electric power generation torque at the time of electric power generation driving | running | working, and a motor operating point change. It is a hardware block diagram of the hybrid vehicle in 1st Embodiment. It is a figure showing the flow of the whole control in 1st Embodiment. It is a figure showing the calculation method of power generation permission lower limit efficiency. It is a figure showing the example of a setting of electric power generation target electrical storage amount. It is a figure showing the correction method of a power generation permission lower limit efficiency line. It is a figure showing the calculation method of the electrical storage amount time change rate. It is a figure showing the example of amendment of the power generation permission efficiency range. It is a figure showing the setting method of the correction | amendment cancellation | release conditions of a power generation permission efficiency range. It is a figure showing the loss by rolling resistance at the time of power generation driving. It is a figure showing the flow of the whole control in 2nd Embodiment. It is a figure showing the magnitude of the power generation efficiency improvement amount. It is a figure showing the calculation method of power generation permission lower limit efficiency improvement amount. It is a figure showing the correction method of a power generation permission lower limit efficiency improvement amount line. It is a figure showing the example of amendment of power generation permission efficiency improvement amount range. It is a figure showing the correction | amendment method of the electric power generation permission efficiency range relevant to a low electrical storage amount stop. It is a figure showing the correction method of the power generation permission efficiency range related to engine water temperature.

--- First embodiment ---
Hereinafter, embodiments of a hybrid vehicle as a power generation control device for a hybrid vehicle of the present invention will be described with reference to the drawings. In each embodiment described below, the hybrid vehicle has a configuration in which the front wheels are driven by an engine and the rear wheels are driven by a motor. However, practically, the same control can be applied to the configuration of a so-called parallel hybrid vehicle in which both the engine and the motor are used for driving regardless of the arrangement of the engine and the motor. It can also be applied when running in parallel mode on series / parallel hybrid vehicles. Furthermore, the hybrid vehicle of the present invention includes an industrial vehicle having a similar configuration in addition to the hybrid vehicle.

  With reference to FIG. 4, each device constituting the hybrid vehicle that is the subject of the present invention will be described. The hybrid vehicle power generation control device of the present invention is applied to, for example, the ECU 411. The driving force by the engine 401 is transmitted to the front wheels 405 through the clutch 402, the transmission 403, and the front differential gear 404, and generates driving force for the road surface 413. A motor 408, which is a driving force source on the rear wheel side, generates torque using the electric power of the battery 406 controlled by the inverter 407. The torque of the motor 408 is transmitted to the rear wheel 410 through the rear differential gear 409 and generates a driving force for the road surface 413. The ECU 411 receives the engine speed, the estimated engine torque, temperature information such as the engine coolant temperature from the engine state detection means 412, the motor speed and the motor torque from the inverter 407, and the tire pressure from the TPMS (Tire Pressure Monitoring System) 416. Can be obtained. Further, the storage amount, current value, and temperature information of the battery 406 can be obtained from the battery controller 415. The ECU 411 determines the engine output and the motor output based on the various information thus obtained, and sends commands to the engine 401, the clutch 402, and the inverter 407. The auxiliary machinery 414 is supplied with power from the battery 406. In FIG. 4, a solid line connecting the devices represents a control bus to which various information is transferred, a broken line represents a flow of charges, and a double line represents conduction of force.

  Next, the overall outline of the control of the present invention will be described with reference to FIG. This control is executed by the ECU 411. If there is a charge request in step S501, in step S502, the vehicle speed, the engine speed, the storage amount, and the accelerator opening are acquired as the vehicle state. If the charged amount is less than or equal to the predetermined allowable lower limit charged amount, forced power generation is performed without performing control for determining permission / prohibition of power generation (step S513). The allowable lower limit storage amount is determined such that the required life is not shorter than the cycle life of the battery. If the allowable lower limit storage amount is small, the battery charge / discharge depth becomes deep, and the cycle life of the battery becomes shorter than the required life. When forced power generation is performed in step S511 and when there is no charge request in step S501, this control is terminated.

In step S503, if the charged amount is larger than the allowable lower limit charged amount, the power generation torque ΔTe is calculated (step S504). The power generation torque is the difference between the engine torque TeGen when power generation is performed and the engine torque TeDrv when power generation is not performed. The engine torque TeDrv when power generation is not performed is calculated based on the required drive torque TaxsDrv on the axle and the transmission gear ratio (reduction ratio) of the transmission 403. The required drive torque TaxsDrv and the transmission gear ratio are calculated based on the vehicle speed VSP and the accelerator opening APO with reference to a map prepared in advance.
TeDrv = TaxsDrv (VSP, APO) / (RatioTm (VSP, APO) * GfF) (1)
TeDrv Engine torque when not generating electricity
TaxsDrv Required drive torque on axle
VSP vehicle speed
APO accelerator opening
RatioTm Transmission reduction ratio
GfF Front final gear reduction ratio

  The engine torque TeGen when power generation is performed is ideally set on the fuel efficiency optimum line of the engine while maintaining the engine speed Ne when power generation is not performed. The engine speed Ne is obtained based on the vehicle speed VSP and the transmission gear ratio of the transmission 403. Based on the engine torque TeGen at the time of power generation determined as described above, the power generation torque ΔTe is obtained as described above. When the power generation torque ΔTe exceeds the power generation torque limit of the motor, it is limited by the value of the power generation torque limit. The power generation torque limit is set as a rating according to the rotational speed Nm, and is set smaller depending on the battery temperature.

Next, in step S505, the power generation operating point efficiency is calculated as a physical quantity related to the charging efficiency of the battery 406 when power generation traveling with the power generation torque ΔTe is assumed. The power generation operating point efficiency is defined by the product of the engine operating point efficiency ηEngGen shown in the equation (3) and the motor operating point efficiency ηMotGen shown in the equation (4) as shown in the following equation (2). In equations (3) and (4), f (x, y) on the right side means that the left side is a function of x and y.
ηGen = ηEngGen * ηMotGen (2)
ηEngGen = f (Ne, TeDrv + ΔTe) (3)
ηMotGen = f (Nm, TmGen) (4)
TmGen = (-1) * TeGen * RatioTm * GfF / GfR (5)
ηGen Power generation operating point efficiency ηEngGen Engine operating point during power generation (point P2 shown in FIG. 2) Efficiency ηMotGen Motor operating point during power generation (point Q2 shown in FIG. 3) Efficiency
Ne engine speed
Nm Motor speed
TmGen Power generation torque (value at motor shaft)
GfR Rear final gear reduction ratio

  Subsequently, in step S506, a power generation permission lower limit efficiency line that is a threshold efficiency of permission / prohibition of power generation is set. The setting of the power generation permission lower limit efficiency line will be described later. In step S507, the amount of charge required for charging the battery 406 (hereinafter referred to as required amount of charge), which is obtained as a difference between the target amount of electricity stored in advance by the ECU 411 and the current amount of electricity acquired by the ECU 411 in step S502. Is calculated). In step S508, the power generation permission lower limit efficiency is calculated based on the required charge amount calculated in step S507 and the power generation permission lower limit efficiency line set in step S506. If the power generation operating point efficiency exceeds the power generation permission lower limit efficiency in step S509, the process proceeds to step S510. If the power generation operating point efficiency is lower than or equal to the power generation permission lower limit efficiency, power generation is prohibited (step S512), and this control is terminated.

  In step S510, whether the power generation travel is effective for improving energy efficiency based on the travel history (vehicle speed, load) for a predetermined time accumulated in the ECU 411 or the travel prediction (vehicle speed, load) based on external information such as car navigation. Determine whether or not. When high-speed cruising continues, there is little opportunity to discharge the energy stored in power generation. In addition, the engine torque TeGen for high-speed cruises is near the optimal fuel efficiency line of the engine, and the efficiency improvement margin for engine driving during discharge is small. Therefore, permission for power generation driving causes a decrease in engine efficiency and negatively improves energy efficiency. May have an effect. This tendency is remarkable when the engine displacement is small. Assume that the determination criterion in step S510 is set in accordance with the physique of the engine and motor at the time of vehicle shipment. If it is determined in step S510 that the power generation travel is effective for improving the energy efficiency, power generation is permitted (step S511), and this control is terminated. Otherwise, power generation is prohibited in step S512 and this control is terminated. To do.

  Details of the calculation of the power generation permission lower limit efficiency (step S506) will be described. In step S508, as shown in FIG. 6, the power generation permission lower limit efficiency is determined based on the power generation permission lower limit efficiency line set in step S506 with the required charge amount calculated in step S507 as an input. The target power storage amount used for calculating the required charge amount is stored in advance by the ECU 411 as described above. As described above, the current power storage amount is acquired by the ECU 411 in step S502. In addition to setting the target power storage amount to a constant value below the allowable upper limit power storage amount, it is also conceivable to set a low value at a high vehicle speed, such as the power generation target power storage amount shown in FIG. When the vehicle speed is high, the energy obtained by deceleration regeneration increases. If the difference between the power generation target power storage amount and the upper limit power storage amount is small, all of the energy obtained by the deceleration regeneration cannot be used for charging the battery 406, and a part of the energy is wasted. Lower. The power generation target power storage amount is set so as to have a margin for the power storage amount that is predicted to be obtained by deceleration regeneration before the vehicle stops, with respect to the predetermined target power storage amount at the time of stopping.

  The power generation permission lower limit efficiency line represents the relationship between the required charge amount and the threshold efficiency at which power generation is permitted / prohibited. As shown in Fig. 6, the smaller the required amount of charge, that is, the lower the urgency of power generation, the lower the efficiency of power generation. The higher the required charge amount, that is, the higher the urgency of power generation, It is set to allow power generation with efficiency. The power generation traveling in the above-described high-speed cruise is permitted when it is effective for improving energy efficiency. With this setting, flexible power generation control is possible according to the urgency of power generation, which contributes to improving the energy efficiency of hybrid vehicles.

  The power generation permission lower limit efficiency line is not limited to the shape shown in FIG. 6, and has a shape that prohibits low-efficiency power generation when the required charge amount is small, and is determined based on various input information input to the ECU 411. The various input information includes, for example, the component characteristics of the engine 401 and the motor 408, the capacity of the battery 406, and the number of charge / discharge cycles. In the control of the present invention, the power generation permission lower limit efficiency line is further corrected based on the separately calculated power storage amount time change rate.

  A method for correcting the power generation permission lower limit efficiency line performed by the ECU 411 will be described with reference to FIG. In step S801, the power generation permission lower limit efficiency reference line stored in the ECU 411 is read and temporarily set as the power generation permission lower limit efficiency line, and the process proceeds to calculation of the storage amount time change rate in step S802.

  The calculation of the storage amount time change rate in step S802 will be described with reference to FIG. The storage amount time change rate is the amount of increase in the storage amount during a predetermined time Δt before this control execution timing. However, when the vehicle speed increases, the motor rotation speed increases, so the rate of change of the stored electricity amount increases. When the vehicle speed decreases, the motor rotation speed decreases, and the rate of change of the stored electricity amount decreases. In order to simplify the determination process in step S804, which will be described later, here, a predetermined reference vehicle speed range is determined so that the rate of change of the charged amount time does not become too large and does not become too small. The predetermined time Δt is counted for a time in which the vehicle speed is included in a predetermined reference vehicle speed range and the accelerator opening is positive. In FIG. 9, the vehicle speed exceeds the reference upper limit speed, which is the upper limit of the reference vehicle speed range, immediately before the execution timing of this control, so it is not included in the predetermined time Δt. Further, when the vehicle speed frequently deviates from the reference vehicle speed range, the data for a predetermined time Δt is totaled for the portion not deviating to calculate the storage amount time change rate. A portion where the vehicle speed deviates from the reference vehicle speed range from the control execution timing to a predetermined time Δt may be subtracted, but Δt ≠ 0 needs to be calculated in order to calculate the storage amount time change rate.

  In step S803, the power storage amount time change rate calculated in step S802 is compared with a power storage amount time change rate upper limit and a power storage amount time change rate lower limit prepared in advance to determine whether there is an abnormality. The reason why the abnormality occurs is, for example, a decrease in the battery SOH, a decrease in the tire air pressure, a decrease in the road surface friction coefficient, or an increase in the power used by the auxiliary equipment. If the storage amount time change rate exceeds the storage amount time change rate upper limit, or if the storage amount time change rate is less than the storage amount time change rate lower limit, it is determined in step S804 that there is an abnormality, and power generation is performed. The allowable lower limit efficiency line is corrected (step S805). As shown in FIG. 10, when the power storage amount time change rate exceeds the power storage amount time change rate upper limit, when power generation is started, the power storage amount of the battery 406 may reach the upper limit power storage amount earlier. By adopting the power generation permission lower limit efficiency upward correction line as the permitted lower limit efficiency line, power generation traveling at low efficiency is prevented. If the storage amount time change rate is less than the storage amount time change rate lower limit, the power storage amount of the battery 406 may reach the upper limit storage amount even if power generation is started. As described above, the power generation permission lower limit efficiency downward correction line is employed to prevent the battery 406 from being insufficiently charged. The power generation permission lower limit efficiency reference line, the power generation permission lower limit efficiency upper correction line, and the power generation permission lower limit efficiency lower correction line are not limited to the shapes shown in FIG. The reference line and the power generation permission lower limit efficiency downward correction line are in this order, and are set in advance so that none of the lines intersect.

  By setting the power generation permission lower limit efficiency line as in step S805, if an abnormality occurs for the reason described above and the increase rate of the storage amount is slow (that is, the storage amount time change rate is small), The permitted efficiency range will be expanded to a lower efficiency side than usual, and the power generation opportunities while driving will increase. Therefore, even if the efficiency is lower than usual, the power storage amount can be quickly recovered by giving priority to power generation. In addition, when an abnormality occurs for the above-described reason and the increase rate of the storage amount is fast (that is, the storage amount time change rate is large), the power generation permission efficiency range is set narrower than usual, and Opportunities are limited to the high efficiency side. Since the power storage time change rate is large, even if the required charge amount is large, the power storage amount can be quickly recovered in a shorter time than usual if power generation travel is started. Therefore, since power generation is permitted only when the efficiency is higher than usual, it is possible to prevent power generation traveling with low efficiency. In this way, both the rapid recovery of the amount of stored electricity and the efficiency of power generation travel are achieved.

  When the upward or downward correction is performed on the power generation permission lower limit efficiency line, the correction cancellation condition for the power generation permission lower limit efficiency line is set in step S806. The setting of the correction cancellation condition will be described later. The correction is maintained until the correction cancellation condition is satisfied in step S807. If the correction cancellation condition is satisfied, the correction is canceled in step S808. Here, canceling the correction means returning the setting of the power generation permission lower limit efficiency line to the power generation permission lower limit efficiency reference line.

  Here, the setting of the power generation permission lower limit efficiency line correction cancellation condition in step S806 in FIG. 8 will be described with reference to FIG. In step S1101, a power storage time change rate during power generation is calculated. The power storage amount time change rate during power generation is calculated by accumulating the amount of change in power storage amount only for the time during which power generation running is performed out of the power storage amount time change rate. The time change rate of the charged amount is calculated based on the total value. Subsequently, it is determined whether or not the power storage time change rate during power generation deviates from the ideal change rate range (step S1102). The ideal change rate range refers to a range in which the rate of change in the amount of stored electricity during power generation changes due to a temporary change in driving conditions. The ideal change rate range is obtained theoretically or experimentally based on, for example, the vehicle speed, the running load, the component characteristics of the engine 401 and the motor 408, and the capacity of the battery 406.

  If there is no departure in step S1102, it can be said that the abnormality in the rate of change of the storage amount time is not an abnormality in the power generation system, but is due to a temporary change in driving conditions. The elapse of a predetermined time after the correction of the efficiency line is set (step S1107). For example, during overtaking, the accelerator opening is increased and the motor is forcibly driven. Therefore, the amount of discharge of the battery 406 may increase, and the rate of change in the amount of charge over time may become abnormal, but this is necessary for overtaking. After a predetermined time (for example, 30 seconds), it is estimated that the vehicle has returned to normal driving conditions. The predetermined time is set according to the temporary change of the driving condition estimated as described above. If the rate of change in the amount of stored electricity during power generation deviates from the ideal rate of change range, it is estimated that the abnormality in the rate of change in amount of stored electricity over time is due to an abnormality in the power generation system. It is determined whether or not each of the parameters that can affect the abnormality in the rate of change in the amount of stored electricity during power generation shown in Table 1 described later deviates from the assumed range shown in Table 1 (steps S1103 and 1104). The assumed range shown in Table 1 is stored in advance by the ECU 411.

  If a parameter deviating from the assumed range is found in step S1104, the correction cancellation condition is set to return to the assumed range corresponding to the parameter in step S1105. For a plurality of parameters, when a parameter that deviates from the assumed range is found, the return of any one parameter to the assumed range is a power generation permission efficiency line correction cancellation condition. If no parameter deviating from the assumed range is found in step S1104, the ideal change rate range return of the stored electricity amount time change rate during power generation is set as the correction cancellation condition in step S1106.

Here, an example of parameters to be checked in step S1103 will be described. Table 1 is a table showing examples of parameters that affect the rate of change in the amount of stored electricity during power generation. Note that the parameters to be checked in step S1103 are not limited to the parameters shown in Table 1, but may be any parameters that can affect the change in the amount of stored electricity during power generation and can be monitored by a sensor or the like.

  SOH (State Of Health), which is a parameter related to the deterioration of the battery 406, can be obtained by estimation using measured values (current, temperature, etc.) in the battery controller 415. The decrease in SOH is caused by the deterioration of the battery 406. Indicates that is progressing. A calculation formula or a data table representing the relationship between the use history of the battery 406, that is, the charge / discharge current history, the temperature history, the time history, etc., and the SOH is obtained in advance by experiment, and the SOH is determined by referring to the calculation formula or data table. presume. As the battery deteriorates, an electrolyte / interelectrode material with less electrical and ionic conductivity grows on the electrode surface, and the resistance during charging / discharging increases, so the rate of increase in the amount of electricity stored during power generation becomes slow. For example, 80% is set as the threshold value of the SOH, and if the estimated SOH is less than that, it is determined that the estimated range is out of range.

  Tire pressure is monitored by TPMS 416. The configuration of the hybrid vehicle 400 having the power generation control device of the present embodiment is such that the engine 401 is disposed at the front and the motor 408 is disposed at the rear, and the battery 406 is charged by the power generation by the motor 408. As shown in FIG. 12, while transmitting the power generation torque generated by the engine 401 to the motor 408, the motor 408 is driven by the rolling resistance between the front wheels 405, the road surface 413, and the road surface 413 driven by the engine 401. Through the rear wheel 410. Therefore, when the tire air pressure decreases and the rolling resistance between the front wheels 405 and the rear wheels 410 and the road surface 413 increases, the power generation torque is lost, and the rate of increase in the amount of stored electricity due to power generation traveling becomes slow. As the tire air pressure threshold, for example, 80% of the standard air pressure of the target vehicle is set. If the tire air pressure monitored by the TPMS is lower than that, it is determined that the tire is deviating from the assumed range.

  The road surface friction coefficient is estimated by a safety device related to vehicle motion (not shown) such as ABS (Antilock Brake System) or VDC (Vehicle Dynamics Control). When the road surface friction coefficient decreases and the driving force transmission rate between the front wheels 405 and the rear wheels 410 and the road surface 413 deteriorates, the power generation torque is lost, and the rate of increase in the amount of power storage due to power generation traveling becomes slow. As the threshold value of the road surface friction coefficient, for example, 0.8, which is about the same as that of wet asphalt, is set.

  The power used by the auxiliary equipment is obtained from the current measurement value in the battery controller 415. The auxiliary machinery 414 is an air conditioner, a car audio system, an electric water pump for cooling, and the like, and when these devices consume a lot of power, the rate of increase in the amount of stored electricity during power generation traveling becomes slow. A threshold value determined in advance through experiments or the like is set as a threshold value for power consumption of auxiliary equipment. If the power consumption of auxiliary equipment exceeds the threshold, it is determined that the estimated range is out of range.

The power generation control device of the first embodiment has the following operational effects.
(1) The power generation control device of the present embodiment calculates the engine torque TeDrv when power generation is not performed, which is necessary for driving the hybrid vehicle 400, based on the vehicle speed Vsp of the hybrid vehicle 400 and the accelerator opening APO. A power generation torque ΔTe is calculated based on the engine speed Ne corresponding to the vehicle speed Vsp and the engine torque TeDrv when power generation is not performed. Based on the engine speed Ne corresponding to the vehicle speed Vsp, the engine torque TeDrv when power generation is not performed, and the power generation torque ΔTe, the power generation operating point efficiency ηGen corresponding to the power generation torque ΔTe is calculated. The necessary amount of charge necessary for charging the battery is calculated, and power generation is prohibited when the power generation operating point efficiency ηGen falls below the threshold efficiency at which power generation is permitted / prohibited. The relationship between the threshold efficiency for permitting / prohibiting power generation and the required charge amount is represented by a power generation permission lower limit efficiency line, and the threshold efficiency for permitting / prohibiting power generation takes a smaller value as the required charge amount is larger. When the storage amount time change rate of the storage amount of the battery 406 is not included in the range between the storage amount time change upper limit and the storage amount time change lower limit, the threshold efficiency for permitting / prohibiting power generation is corrected. By flexible power generation control according to the amount of electricity stored in the battery, high-efficiency power generation is given priority when there is a margin in the amount of electricity stored, and when there is no margin in the amount of electricity stored, the amount of electricity stored can be recovered quickly. There is an effect of being compatible.

(2) The power generation control device according to the present embodiment raises the threshold efficiency for permitting / prohibiting power generation when the power storage time change rate exceeds the power storage time change rate upper limit, and the power storage time change rate changes the power storage time change. When the rate falls below the lower limit, the threshold efficiency for enabling / disabling power generation is reduced. With such flexible power generation control according to the rate of change in the amount of charge of the battery, high-efficiency power generation is preferentially performed when the rate of change in the amount of charge is large, while the amount of charge is quickly adjusted when the rate of change in the amount of charge is small. There is an effect that it is possible to achieve both recovery.

--- Second Embodiment ---
In the first embodiment, in order to determine permission / prohibition of power generation control, the power generation operating point efficiency and the power generation permission lower limit efficiency are compared as shown in step S507 in FIG. The determination may be made based on the comparison between the power generation efficiency improvement amount and the power generation permission lower limit efficiency improvement amount according to the processing procedure shown in FIG. The power generation efficiency improvement amount is a physical amount related to the charging efficiency of the battery 406 when power generation traveling is assumed, and details thereof will be described later. Although FIG. 13 will be described below, only steps S1305, S1306, S1307, S1308, and S1309 different from FIG. 5 will be described.

The amount of improvement in power generation efficiency is given as the difference between the engine efficiency when power generation is performed and the engine efficiency when power generation is not performed. The engine efficiency when power generation is performed is the engine efficiency at the power generation operation point (point P1b or P2b) shown in FIG. 14. The engine efficiency when power generation is not performed is the operation point (points when power generation is not performed) shown in FIG. Engine efficiency in P1a or P1b). The operating point moves from the operating point when power generation is not performed to the operating point when power generation is performed that is determined according to the power generation torque ΔTe calculated in step S1304. In step S1305, the power generation efficiency improvement amount ΔηGen is calculated according to the following equations (6) and (7). As shown in the left graph (a) of FIG. 14, when the power generation efficiency improvement amount is small, the power generation efficiency improvement amount ΔηGen is also small, and as shown in the right graph (b) of FIG. When the amount is large, the power generation efficiency improvement amount ΔηGen also increases.
ΔηGen = ηEngGen-ηEngNoGen = f (Ne, ΔTe) (6)
ηEngNoGen = f (Ne, TeDrv) (7)
ηEngNoGen Engine efficiency when not generating electricity

  Subsequently, in step S1306, a power generation permission lower limit efficiency improvement amount line that is a threshold value for permission / prohibition of power generation is set. The setting of the power generation permission lower limit efficiency improvement amount line will be described later. In step S1307, the required charge amount calculated as a difference between the target power storage amount stored in advance by the ECU 411 and the current power storage amount acquired by the ECU 411 in step S1302 is calculated. In step S1308, the power generation permission lower limit efficiency improvement amount is calculated based on the necessary charge amount calculated in step S1307 and the power generation permission lower limit efficiency improvement amount line set in step S1306. If the power generation efficiency improvement amount exceeds the power generation permission lower limit efficiency improvement amount in step S1309, the process proceeds to step S1310. When the power generation efficiency improvement amount is less than or equal to the power generation permission lower limit efficiency improvement amount, power generation is prohibited (step S1312).

  In step S1308, the power generation permission lower limit efficiency improvement amount is input based on the power generation permission lower limit efficiency improvement amount line set in step S1306 with the required charge amount calculated in step S1307 as an input, as shown in FIG. It is decided. The power generation permission lower limit efficiency improvement amount line shows the relationship between the required charge amount and the efficiency improvement amount which is a threshold value for permitting / prohibiting power generation. As shown in FIG. The lower the value, the smaller the efficiency improvement amount is forbidden, and when the required charge amount is larger than a predetermined value, that is, the urgency of power generation is high, the power generation of any efficiency improvement amount is permitted. With this setting, flexible power generation control is possible according to the urgency of power generation, which contributes to improving the energy efficiency of hybrid vehicles. The power generation permission lower limit efficiency improvement amount line is not limited to the shape of FIG. 15, and is a shape that prohibits power generation with a small efficiency improvement amount when the required charge amount is small, and includes various input information input to the ECU 411. Determine based on. The various input information includes, for example, the component characteristics of the engine 401 and the motor 408, the capacity of the battery 406, and the number of charge / discharge cycles. In the control according to the present invention, the power generation permission lower limit efficiency improvement amount curve is corrected based on a separately calculated power storage amount time change rate.

  A method for correcting the power generation permission lower limit efficiency improvement amount line will be described with reference to FIG. In step S1601, the power generation permission lower limit efficiency improvement amount reference line stored in the ECU 411 is read and temporarily set as the power generation permission lower limit efficiency improvement amount line, and the process proceeds to calculation of the storage amount time change rate in step S1602. The calculation of the stored electricity amount time change rate in step S1602 is the same as that in step S802 in the first embodiment, and is therefore omitted.

  In step S1603, the power storage amount time change rate calculated in step S1602 is compared with a power storage amount time change rate upper limit and a power storage amount time change rate lower limit prepared in advance to determine whether there is an abnormality. The reason why the abnormality occurs is, for example, a decrease in the battery SOH, a decrease in the tire air pressure, a decrease in the road surface friction coefficient, or an increase in the power used by the auxiliary equipment. If the storage amount time change rate exceeds the storage amount time change rate upper limit, or if the storage amount time change rate is less than the storage amount time change rate lower limit, it is determined in step S1604 that there is an abnormality, The permission lower limit efficiency improvement amount curve is corrected (step S1605). As shown in FIG. 17, when the power storage time change rate exceeds the power storage time change rate upper limit, the power generation permission lower limit efficiency improvement amount upward correction line is adopted as the power generation permission lower limit efficiency improvement amount line, and the power storage time When the rate of change is less than the lower limit of the storage amount time change rate, the power generation permission lower limit efficiency improvement lower correction line is adopted as the power generation permission lower limit efficiency improvement amount line. The power generation permission lower limit efficiency improvement amount reference line, the power generation permission lower limit efficiency improvement amount upward correction line, and the power generation permission lower limit efficiency improvement amount lower correction line are not limited to the shape of FIG. The order is an upper correction line, a power generation permission lower limit efficiency improvement amount reference line, and a power generation permission lower limit efficiency improvement lower correction line, which are set in advance so that none of the lines intersect.

  By setting the power generation permission lower limit efficiency improvement amount line as in step S1605, when the abnormality occurs for the reason described above and the increase rate of the storage amount is slow (that is, the storage amount time change rate is small). , The power generation permission efficiency range is expanded to the lower efficiency side than usual, and the power generation opportunities while driving are increased. Therefore, even if the efficiency is lower than usual, the power storage amount can be quickly recovered by giving priority to power generation. In addition, when an abnormality occurs for the above-described reason and the increase rate of the storage amount is fast (that is, the storage amount time change rate is large), the power generation permission efficiency range is set narrower than usual, and Opportunities are limited to the high efficiency side. Since the power storage time change rate is large, even if the required charge amount is large, the power storage amount can be quickly recovered in a shorter time than usual if power generation travel is started. Therefore, since power generation is permitted only when the efficiency is higher than usual, it is possible to prevent power generation traveling with low efficiency. In this way, both the rapid recovery of the amount of stored electricity and the efficiency of power generation travel are achieved.

  When the upward or downward correction is performed on the power generation permission lower limit efficiency improvement amount line, a correction cancellation condition for the power generation permission lower limit efficiency improvement amount line is set in step S1606. Since the setting of the correction cancellation condition is the same as that of the first embodiment, the description thereof is omitted. The correction is maintained until the correction cancellation condition is satisfied in step S1607. If the correction cancellation condition is satisfied, the correction is canceled in step S1608. Here, canceling the correction means returning the setting of the power generation permission lower limit efficiency improvement amount line to the power generation permission lower limit efficiency improvement amount reference line.

The power generation control device of the second embodiment has the following operational effects.
(1) The power generation control device of the present embodiment calculates the engine torque TeDrv when power generation is not performed, which is necessary for driving the hybrid vehicle 400, based on the vehicle speed Vsp of the hybrid vehicle 400 and the accelerator opening APO. A power generation torque ΔTe is calculated based on the engine speed Ne corresponding to the vehicle speed Vsp and the engine torque TeDrv when power generation is not performed. A power generation efficiency improvement amount ΔηGen corresponding to the power generation torque ΔTe is calculated based on the engine speed Ne corresponding to the vehicle speed Vsp, the engine torque TeDrv when power generation is not performed, and the power generation torque ΔTe. A necessary charge amount necessary for charging the battery is calculated, and power generation is prohibited when the power generation efficiency improvement amount ΔηGen falls below an efficiency improvement amount that is a threshold value for permitting / prohibiting power generation. The relationship between the efficiency improvement amount that is a threshold value for permitting / prohibiting power generation and the required charge amount is represented by a power generation permission lower limit efficiency improvement amount line, and the efficiency improvement amount that is a threshold value for permitting / prohibiting power generation increases as the required charge amount increases. Take a small value. When the storage amount time change rate of the storage amount of the battery 406 is not included in the range between the storage amount time change upper limit and the storage amount time change lower limit, an efficiency improvement amount that is a threshold value for permitting / prohibiting power generation is set. to correct. By flexible power generation control according to the amount of electricity stored in the battery, high-efficiency power generation is given priority when there is a margin in the amount of electricity stored, and when there is no margin in the amount of electricity stored, the amount of electricity stored can be recovered quickly. There is an effect of being compatible.

(2) The power generation control device according to the present embodiment raises the efficiency improvement amount, which is a threshold value for permitting / prohibiting power generation, when the power storage time change rate exceeds the power storage time change rate upper limit. When the stored energy amount time change rate lower limit is not reached, the efficiency improvement amount, which is a threshold value for permitting / prohibiting power generation, is reduced. With such flexible power generation control according to the rate of change in the amount of charge of the battery, high-efficiency power generation is preferentially performed when the rate of change in the amount of charge is large, while the amount of charge is quickly adjusted when the rate of change in the amount of charge is small. There is an effect that it is possible to achieve both recovery.

---- Modified example ---
The power generation control apparatus of the embodiment described above can be modified as follows.
(1) It is also conceivable to add information other than the storage amount information to the correction of the power generation permission lower limit efficiency line of the first embodiment. The modification using route guidance information is shown. As the correction of the power generation permission lower limit efficiency line in the calculation of the power generation permission lower limit efficiency (FIG. 5, step S506), the correction based on the comparison result between the storage amount time change rate, the storage amount time change upper limit and the storage amount time change lower limit ( In addition to FIG. 8, steps S804 to 808), correction as shown in FIG. 18 can also be performed. That is, when stopping at a storage amount lower than the storage amount necessary for stopping in the near future is predicted by route guidance information (steps S1801 and 1802), a power generation permission lower limit efficiency lower correction line is employed (step S1801, 1802). S1803).

  This correction allows forced power generation to be performed at the next start by stopping when the vehicle stops at an amount less than the amount of electricity required when the vehicle is stopped, and the amount of electricity stored is reduced by the auxiliary machine power consumption while the vehicle is stopped. It is executed for the purpose of suppressing unavoidable circumstances. The amount of electricity necessary for stopping is larger than the allowable lower limit amount of electricity and smaller than the target amount of electricity stored, and the difference from the allowable lower limit amount of electricity should be set larger as the auxiliary machine power consumption is larger. When the power generation permission lower limit efficiency downward correction line is adopted in step S1803, a correction cancellation condition is set in step S1804. The correction cancellation condition is, for example, that the charged amount becomes larger than the charged amount required when the vehicle is stopped or that the scheduled stop is cancelled.

  The correction can also be applied to the correction of the power generation permission lower limit efficiency improvement amount in the calculation of the power generation permission lower limit efficiency improvement amount (FIG. 13, step S1306) of the second embodiment.

  In the power generation control device of the modification (1), the hybrid vehicle 400 is scheduled to stop, and the predicted value of the storage amount of the battery 406 when the hybrid vehicle 400 stops at the planned stoppage location is When the amount of power storage required when the automobile 400 stops in the near future, the threshold efficiency or the efficiency improvement amount for permitting / prohibiting power generation is lowered. Thereby, there is an effect that the possibility that the charged amount of the battery 406 falls below the allowable lower limit charged amount while the hybrid vehicle 400 is stopped can be reduced, and the forced power generation can be suppressed.

(2) It is also conceivable to add information other than the storage amount information and the route guidance information to the correction of the power generation permission lower limit efficiency line of the first embodiment. An example that considers the state of the engine 401 is shown. As the correction of the power generation permission lower limit efficiency line in the calculation of the power generation permission lower limit efficiency (FIG. 5, step S506), the correction based on the comparison result between the storage amount time change rate, the storage amount time change upper limit and the storage amount time change lower limit ( In addition to FIG. 8, steps S804 to 808), correction as shown in FIG. 19 can also be performed. That is, when the engine water temperature is lower than a predetermined water temperature stored in advance by the ECU 411 (step S1901), the power generation permission lower limit efficiency lower correction line is adopted (step S1902). This correction is executed for the purpose of facilitating permission for power generation running using the engine at a high load and suppressing deterioration of exhaust efficiency due to a decrease in the temperature of the exhaust catalyst due to a low engine water temperature. When the power generation permission lower limit efficiency downward correction line is adopted in step S1902, a correction cancellation condition is set in step S1903. The correction cancellation condition is, for example, that the engine water temperature is equal to or higher than a predetermined water temperature.

  The correction can also be applied to the correction of the power generation permission lower limit efficiency improvement amount in the calculation of the power generation permission lower limit efficiency improvement amount (FIG. 13, step S1306) of the second embodiment.

  The power generation control device of the modified example (2) lowers the threshold efficiency or the efficiency improvement amount that permits / inhibits power generation when the temperature of the cooling water that cools the engine is lower than a predetermined water temperature that the ECU 411 stores in advance. As a result, it is possible to easily permit power generation running using the engine at a high load, and to suppress deterioration in exhaust efficiency due to a decrease in the temperature of the exhaust catalyst due to a low engine water temperature.

400 Hybrid vehicle 401 Engine 402 Clutch 403 Transmission 404 Front differential gear 405 Front wheel 406 Battery 407 Inverter 408 Motor 409 Rear differential gear 410 Rear wheel 411 ECU
412 Engine state detection means 413 Road surface 414 Auxiliary machinery 415 Battery controller 416 TPMS (Tire Pressure Monitoring System)

Claims (9)

A power generation control device that is mounted on a hybrid vehicle and controls power generation by a motor for charging a battery according to power generation torque generated by an engine,
Torque calculation means for calculating the required driving torque necessary for driving the hybrid vehicle based on the vehicle speed and the accelerator opening of the hybrid vehicle, and calculating the power generation torque based on the vehicle speed and the required driving torque;
Based on the vehicle speed, the required drive torque, and the power generation torque, a physical quantity calculation means for calculating a physical quantity related to the charging efficiency of the battery according to the power generation torque;
A charge amount calculating means for calculating a charge amount necessary for charging the battery;
Power generation prohibiting means for prohibiting the power generation when the physical quantity falls below a predetermined lower limit;
Correction means for correcting the predetermined lower limit value when the storage amount time change rate of the storage amount of the battery is not included in the first predetermined range;
The power generation control device, wherein the predetermined lower limit value is smaller as the required charge amount is larger. The power generation control device according to claim 1,
The correction means raises the predetermined lower limit value when the storage amount time change rate exceeds an upper limit of the first predetermined range, and when the storage amount time change rate falls below the first predetermined range, A power generation control device characterized by lowering a predetermined lower limit value. The power generation control device according to claim 2,
A correction cancellation unit that cancels the correction of the predetermined lower limit value by the correction unit;
When the correction means corrects the predetermined lower limit value and the power storage amount time change rate during power generation during power generation deviates from a second predetermined range, the power storage amount during power generation The power generation control device according to claim 1, wherein when the rate of time change is restored to the second predetermined range, the correction canceling unit cancels the correction. The power generation control device according to claim 2,
Obtaining means for obtaining sensor information indicating an operating state of the hybrid vehicle;
Correction cancellation means for canceling the correction of the predetermined lower limit value by the correction means,
The operation when the correction means corrects the predetermined lower limit value, and the rate of change of the charged amount during power generation during power generation deviates from a second predetermined range, and the sensor information indicates When the state deviates from a predetermined level, the correction canceling unit cancels the correction when the operating state returns to the predetermined level. The power generation control device according to claim 2,
A correction cancellation unit that cancels the correction of the predetermined lower limit value by the correction unit;
When the correction means corrects the predetermined lower limit value, and the power storage amount time change rate during power generation during the power generation is within a second predetermined range, the correction means The power generation control device according to claim 1, wherein when the predetermined time has elapsed after correcting the predetermined lower limit value, the correction canceling unit cancels the correction. In the electric power generation control apparatus of any one of Claims 1-5,
When the hybrid vehicle is scheduled to stop, detection is performed to detect whether or not a predicted value of the storage amount when the hybrid vehicle stops at a planned stop location where the stop is scheduled is less than a predetermined storage amount Further comprising means,
When the detection unit detects that the predicted value is less than the predetermined storage amount, the correction unit reduces the predetermined lower limit value. In the electric power generation control apparatus of any one of Claims 1-6,
The power generation control device according to claim 1, wherein when the temperature of the cooling water for cooling the engine is lower than a predetermined temperature, the correction means lowers the predetermined lower limit value. In the electric power generation control apparatus of any one of Claims 1-7,
The power generation control device according to claim 1, wherein the physical quantity is a power generation operating point efficiency at the time of power generation according to the power generation torque. In the electric power generation control apparatus of any one of Claims 1-7,
The physical quantity is a difference between an operating point efficiency of the engine when the motor generates power according to the power generation torque and an operating point efficiency of the engine when the motor does not generate power. apparatus.

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