control device

Abstract

To prevent over-discharge of a power storage device.SOLUTION: A control device controls an engine, a first motor, and a second motor to ensure required braking torque through fuel cut of the engine or vehicle operation and engine motoring with the first motor when the accelerator is not engaged. During a reduction process to decrease the required braking torque while the engine is under fuel cut control with the accelerator disengaged, the control device maintains the fuel cut control of the engine under conditions where a control lifting condition for lifting the fuel cut control of the engine is satisfied and a manual range is selected through a shift selection device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device. [Background technology]

[0002] Conventionally, a control device of this type has been proposed that is mounted on a vehicle equipped with a multi-cylinder engine and a filter that collects particulate matter in the exhaust gas from the engine (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-127709 Summary of the Invention [Problem to be solved by the invention]

[0004] In a vehicle in which a first motor, an engine, and a second motor are connected to the sun gear, carrier, and ring gear of a planetary gearbox and a manual range is selectable, a system has been proposed that limits engine fuel cutoff to prevent filter overheating when the accelerator is released. In this vehicle, limiting engine fuel cutoff when the accelerator is released reduces engine friction and reduces the so-called engine braking torque that occurs when the engine is motored by the first motor. In this case, increasing the regenerative torque of the second motor to achieve the vehicle's required braking torque may result in the input power of the power storage device significantly exceeding the input limit. Therefore, a reduction process may be performed to reduce the required braking torque, thereby suppressing an increase in the regenerative torque of the second motor and suppressing an increase in the input power of the power storage device. If the manual range is selected when the fuel cutoff limit is released during this reduction process, the discharge power of the power storage device used to increase the engine speed by the first motor may exceed the input power of the power storage device due to the regenerative torque of the second motor, resulting in excessive discharge.

[0005] The control device of the present disclosure has a primary object to prevent the power storage device from being excessively discharged. [Means for solving the problem]

[0006] A control device of the present disclosure is mounted on a vehicle including an engine, a first motor, a second motor, a planetary gear having three rotating elements respectively connected to the first motor, the engine, and the second motor, an electricity storage device capable of exchanging electric power with the first and second motors, and a shift selection device that selects one shift range from a plurality of shift ranges including a manual range that brings the behavior of the engine closer to the behavior of an engine mounted on a vehicle including the engine and a transmission, and that controls the engine and the first and second motors when an accelerator is released so that a required braking torque is realized by cutting off fuel or operating the engine and motoring the engine by the first motor, When the accelerator is released and a reduction process is executed to reduce the required braking torque while the engine fuel cut is restricted, if a restriction release condition for releasing the engine fuel cut restriction is met and the manual range is selected by the shift selection device, the engine fuel cut restriction is continued. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle 20. [Figure 2] 10 is a flowchart illustrating an example of a processing routine. [Figure 3] FIG. 10 is an explanatory diagram of an example of time-dependent changes in a fuel cut limit flag Ffc and the like. DETAILED DESCRIPTION OF THE INVENTION

[0008] Next, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a hybrid vehicle 20 equipped with a control device according to the embodiment. As shown in the figure, the hybrid vehicle 20 includes an engine 22, an engine electronic control unit (hereinafter referred to as "engine ECU") 28, a planetary gear 30, motors MG1 and MG2 (first and second motors), inverters 41 and 42, a battery (power storage device) 50, a transmission 60, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70. The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or diesel. An exhaust system of the engine 22 is equipped with a purification device 25 that purifies unburned fuel and nitrogen oxides in the exhaust of the engine 22, and a PM filter 26 that collects particulate matter (PM) such as soot in the exhaust. The operation of the engine 22 is controlled by the engine ECU 28. The engine ECU 28 has a microcomputer that receives signals from various sensors, outputs various control signals, performs various calculations, and communicates with the HVECU 70. For example, the engine ECU 28 receives inputs such as the crank angle θcr of the crankshaft 23 of the engine 22 from the crank position sensor 23a, the intake air amount Qa of the engine 22 from the air flow meter, and the differential pressure ΔPf before and after (upstream and downstream) the PM filter 26 from the differential pressure sensor 26a. The engine ECU 28 calculates the rotation speed Ne of the engine 22 based on the crank angle θcr, and calculates the load factor KL of the engine 22 (the ratio of the volume of air actually taken in per cycle to the stroke volume per cycle of the engine 22) based on the intake air amount Qa and the rotation speed Ne. The engine ECU 28 calculates the PM accumulation amount Qpm (the amount of particulate matter accumulated on the PM filter 26) based on the differential pressure ΔPf, and calculates the filter temperature Tf (the temperature of the PM filter 26) based on the rotation speed Ne and the load factor KL. The planetary gear 30 is configured as a single-pinion planetary gear mechanism, with the rotor of the motor MG1 connected to the sun gear, the crankshaft 23 of the engine 22 connected to the carrier, and the ring gear connected to an intermediate shaft 35. The rotor of the motor MG2 is attached to the intermediate shaft 35.The motors MG1 and MG2 are configured as, for example, synchronous generator motors, and are rotationally driven by the HVECU 70 controlling the switching of multiple switching elements of the inverters 41 and 42. The battery 50 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the power line 54 together with the inverters 41 and 42. The battery 50 is managed by the HVECU 52. The transmission 60 is configured as a stepped transmission, for example, with four, five, or six speeds. The input shaft of the transmission 60 is connected to the intermediate shaft 35, and the output shaft is connected to the drive shaft 36, which is coupled to the drive wheels 39a and 39b via a differential gear 38. The transmission 60 is controlled by the HVECU 70. The HVECU 70 has a microcomputer that receives signals from various sensors, outputs various control signals, performs various calculations, and communicates with the engine ECU 28. For example, the inputs include rotational positions θm1, θm2 of the rotors of motors MG1, MG2 from rotational position sensors 43, 44, and voltage Vb, current Ib, and temperature Tb of battery 50 from voltage sensor 51a, current sensor 51b, and temperature sensor 51c. Other inputs include a start signal from start switch 80, a shift position (operational position of shift lever (shift selection device)) SP from shift position sensor 82, accelerator opening (amount of accelerator pedal depression) Acc from accelerator pedal position sensor 84, brake pedal position (amount of brake pedal depression) BP from brake pedal position sensor 86, and vehicle speed V from vehicle speed sensor 87. Control signals are output to inverters 41, 42, transmission 60, etc. Based on the rotational positions θm1, θm2, rotational speeds Nm1, Nm2 of motors MG1, MG2 are calculated. The power Pb of the battery 50 is calculated as the product of the voltage Vb and the current Ib, the power storage percentage SOC of the battery 50 is calculated based on the integrated value of the current Ib, and the input / output limits (allowable input / output power) Win, Wout of the battery 50 are calculated based on the power storage percentage SOC and the temperature Tb. As the shift position SP, a parking range (P range), a reverse range (R range), a neutral range (N range), a forward range (D range), a manual range (M range), etc. are prepared.The manual range (M range) is provided with an upshift range (+ range) and a downshift range (- range). In the M range, the engine 22 and the motors MG1 and MG2 are controlled so that the behavior of the engine 22 approaches the behavior of an engine installed in an automobile equipped with an engine and a stepped transmission.

[0009] In the hybrid vehicle 20, the engine 22, motors MG1, MG2, and transmission 60 are controlled by cooperative control between the engine ECU 28 and the HVECU 70 so that the vehicle travels in an electric travel mode (EV travel mode) in which the engine 22 is stopped, or in a hybrid travel mode (HV travel mode) in which the engine 22 is running. The transmission 60 is controlled so that the gear Gs becomes a target gear Gs* based on the accelerator opening Acc and the vehicle speed V when the shift position SP is in the D range, and is controlled so that the gear Gs becomes a target gear Gs* based on the shift position SP when the shift position SP is in the M range. The engine 22 and motors MG1, MG2 are controlled so that the required torque Ti* of the intermediate shaft 35 is output to the intermediate shaft 35 with the engine 22 running or stopped. The required torque Ti* is obtained by dividing the required torque Td* of the drive shaft 36, which is based on the accelerator pedal position Acc and the vehicle speed V, by the rotation speed ratio Gt corresponding to the gear position Gs of the transmission 60. In particular, when the accelerator is released in HV driving mode, the engine 22 and motors MG1, MG2 are controlled so that the required braking torque Ti2* of the intermediate shaft 35 is output to the intermediate shaft 35 by the so-called engine brake torque that acts on the intermediate shaft 35 due to fuel cut or operation of the engine 22 and motoring of the engine 22 by the motor MG1, and the regenerative torque of the motor MG2. The required braking torque Ti2* is obtained by dividing the required braking torque Td2* of the drive shaft 36 by the rotation speed ratio Gt of the transmission 60. The required braking torque Td2* is set to the above-mentioned required torque Td* (torque on the braking side, hereinafter referred to as "basic braking torque Td2a") when the accelerator pedal position Acc is zero, or a torque smaller than that within the braking side range. In the following explanation of when the accelerator is released, for ease of explanation, with the exception of Figure 3, the absolute values ​​of the braking side torque of the drive shaft 36 and the intermediate shaft 35 (required braking torque Td2*, Ti2*, engine brake torque, regenerative torque of the motor MG2) and the input side power of the battery 50 (power Pb and input limit Win) will be omitted (assumed to be positive).The motor MG1 is controlled so that the engine 22 rotates at a target rotation speed Ne*, and the motor MG2 is controlled so that a torque equal to the difference between the required braking torque Ti2* and an engine braking torque estimated, for example, based on the torque of the motor MG1 is output. At this time, the battery 50 is charged and discharged based on the electric power of the motors MG1 and MG2. The engine 22 performs a fuel cut when the filter temperature Tf is less than a threshold value Tfref that is slightly lower than the overheat temperature of the PM filter 26. As a result, air (oxygen) is supplied to the PM filter 26, causing particulate matter deposited on the PM filter 26 to burn and regenerate the PM filter 26. When the filter temperature Tf is equal to or higher than the threshold value Tfref, the engine 22 operates with a limited fuel cut and a relatively small amount of fuel (for example, the lower limit amount that can be combusted) injected to prevent the PM filter 26 from overheating. In this case, compared to when fuel is cut, the friction of the engine 22 is reduced, resulting in a smaller engine brake torque. This increases the regenerative torque of the motor MG2 to achieve the required braking torque Td2* (required braking torque Ti2*), and the electric power Pb of the battery 50 increases toward charging. When the shift position SP is in the D range, the target rotation speed Ne* is set to the basic rotation speed Nea when the electric power Pb of the battery 50 has a margin above the input limit Win. When the electric power Pb reaches the input limit Win, the target rotation speed Ne* is increased within a range below the allowable upper limit rotation speed Nemax relative to the basic rotation speed Nea. For example, the rotation speed Ne immediately before the accelerator is released is used as the basic rotation speed Nea. The target rotation speed Ne* is increased to accommodate the decrease in electric power Pb due to the increase in electric power consumption of the motor MG1 and the decrease in regenerative power of the motor MG2. The increase in the target rotation speed Ne* is set so that the electric power Pb has a margin above the input limit Win. When the shift position SP is in the M range, the target rotation speed Ne* is set using the vehicle speed V, the target gear Gs* of the transmission 60, and a target rotation speed setting map. In the target rotation speed setting map, the target rotation speed Ne* is set so that it increases linearly as the vehicle speed V increases at each gear, and so that the slope with respect to the vehicle speed V decreases as the gear Gs increases.As a result, when the engine 22 is operated at the target rotation speed Ne*, the rotation speed Ne of the engine 22 increases as the vehicle speed V increases in each gear of the transmission 60, the rotation speed Ne of the engine 22 decreases when the gear Gs is upshifted, and the rotation speed Ne of the engine 22 increases when the gear Gs is downshifted. By setting the target rotation speed Ne* of the engine 22 in this manner, the behavior of the rotation speed Ne of the engine 22 is made to resemble the behavior of an engine mounted on a vehicle equipped with an engine and a stepped transmission. As described above, when fuel cut is limited, friction of the engine 22 is reduced compared to when fuel cut is performed, and the engine brake torque is reduced. This increases the regenerative torque of the motor MG2 to realize the required braking torque Td2* (required braking torque Ti2*), which increases the electric power Pb of the battery 50 toward charging. This may cause the electric power Pb of the battery 50 to greatly exceed the input limit Win. In order to prevent the electric power Pb of the battery 50 from significantly exceeding the input limit Win, it is determined whether the input limit Win is smaller than a normal range. If it is determined that the input limit Win is smaller than the normal range, a process for reducing the required braking torque Td2* is performed. In the embodiment, when a first condition is met, in which the electric power Pb of the battery 50 is equal to the input limit Win and the rotation speed Ne of the engine 22 is equal to or greater than a threshold Neref that is lower than the allowable upper limit rotation speed Nemax, the input limit Win is determined to be smaller than the normal range. If the first condition is not met, the input limit Win is determined to be within the normal range. The threshold Neref is set to be higher as the vehicle speed V increases, taking into account that the allowable background noise increases as the vehicle speed V increases. Note that a constant value may be used for the threshold Neref. The first condition means that the electric power Pb reaches the input limit Win because the input limit Win is small, and the target rotation speed Ne* (rotation speed Ne) is raised. The input limit Win may be small when the power storage rate SOC of the battery 50 is sufficiently high or when the temperature Tb of the battery 50 is sufficiently low. In the reduction process, when it is determined whether the input limit Win is smaller than the normal range, the required braking torque Td2* is gradually reduced from the basic braking torque Td2a, and the reduction of the required braking torque Td2* is completed.The amount of reduction in the required braking torque Td2* is set based on the vehicle speed V, etc. Reducing the required braking torque Td2* (required braking torque Ti2*) prevents the regenerative torque of the motor MG2 from increasing, and prevents the power Pb of the battery 50 from significantly exceeding the input limit Win. If the reduction process is executed during a trip, the required braking torque Td2* is set to a torque that is smaller than the basic braking torque Td2a and within the braking range when the accelerator is released, until the end of the current trip. This makes it possible to prevent frequent large changes in the required braking torque Td2* during the trip.

[0010] Next, the operation of the hybrid vehicle 20 will be described, particularly the process for determining whether to lift the fuel cut restriction when the fuel cut restriction is imposed when the accelerator is released in HV driving mode. FIG. 2 is a flowchart showing an example of a processing routine executed by the HVECU 70. This routine is repeatedly executed at predetermined time intervals (e.g., every few milliseconds) when the accelerator is released in HV driving mode. When this routine is executed, the HVECU 70 first determines whether the fuel cut restriction of the engine 22 is imposed (step S100), whether the required braking torque Td2* is being reduced (step S110), and whether a restriction lifting condition for lifting the fuel cut restriction is satisfied (step S120). The determination process in step S100 is performed, for example, by checking the value of a fuel cut restriction flag Ffc. The engine ECU 28 sets the fuel cut restriction flag Ffc to a value of 0 when the engine 22 is to be cut or restricted, respectively, and transmits the value to the HVECU 70. The determination process in step S110 is performed, for example, by checking the value of a reduction process flag Ftl. The reduction process flag Ftl is set to a value of 1 or a value of 0 when the HVECU 70 performs reduction process of the required braking torque Td2* or does not perform reduction process of the required braking torque Td2*, respectively. The determination process in step S120 is performed by checking the filter temperature Tf. The restriction release condition is determined to be met when the filter temperature Tf is less than the threshold value Tfref, and is determined to be not met when the filter temperature Tf is equal to or greater than the threshold value Tfref. If, in steps S100 to S120, the fuel cut restriction is not in progress, reduction process is not in progress, or the restriction release condition is not met, this routine is terminated.

[0011] In steps S100-S120, if fuel cut restriction is in progress, reduction processing is in progress, and the restriction release condition is met, it is determined whether the shift position SP is in the M range (step S130). If it is determined in step S130 that the range is not the M range, the fuel cut restriction is released (step S140), and the routine ends. This allows fuel to be cut. If it is determined in step S130 that the range is the M range, the fuel cut restriction is continued (step S150), and the routine ends. This allows fuel to be cut. FIG. 3 is an explanatory diagram illustrating an example of time-dependent changes in the fuel cut restriction flag Ffc, the reduction processing flag Ftl, the rotation speed Ne of the engine 22, the shift position SP, and the charge / discharge balance of the battery 50. In the diagram, the charge / discharge balance is indicated as a positive value when the battery 50 is discharging and a negative value when it is charging. During the reduction process when the reduction process flag Ftl has the value 1, as shown by the dashed line in the figure, if the restriction release condition is met, the fuel cut restriction is released, and the fuel cut restriction flag Ffc becomes 0 (time t1), the friction of the engine 22 increases, the engine braking torque increases, the regenerative torque of the motor MG2 decreases to realize the required braking torque Td2*, and the power used to charge the battery 50 by the regenerative torque of the motor MG2 decreases. At this time, if the rotation speed Ne of the engine 22 is increased by the motor MG1 in the M range, the power consumption by the motor MG1 increases, and the battery 50 will be over-discharged in the charge / discharge balance. In this embodiment, even if the restriction release condition is met during reduction processing when the reduction processing flag Ftl is set to the value 1, the fuel cut restriction continues in the M range (the fuel cut restriction flag Ffc becomes the value 1) (at time t1), which reduces the friction of the engine 22 and reduces the engine brake torque compared to when fuel cut is performed, and the regenerative torque of the motor MG2 increases to realize the required braking torque Td2*, thereby increasing the power used to charge the battery 50. This makes it possible to prevent the battery 50 from being over-discharged in the charge / discharge balance.

[0012] According to the control device of the embodiment described above, when the accelerator is released and a reduction process is executed during the restriction of fuel cut of the engine 22, if the restriction release condition is met and the M range is selected, the restriction of fuel cut is continued, thereby preventing the battery 50 from being excessively discharged.

[0013] In the control device of the embodiment, if the input limit Win is greater than the output limit Wout when it is determined in step S130 that the range is M, the fuel cut restriction may be lifted. Also, the transmission 60 may be a continuously variable transmission. Furthermore, the control device of the embodiment may be applied to a vehicle that does not include the transmission 60 and virtually approximates the behavior of the engine to the behavior of the engine of a vehicle that includes a transmission.

[0014] The present disclosure is not limited to the above-described embodiments, and it goes without saying that the present disclosure can be implemented in various forms without departing from the spirit of the present disclosure. [Explanation of symbols]

[0015] 20 Hybrid Vehicles, 28 Engine ECUs, 70 HVECUs.

Claims

[Claim 1] a transmission connected to a drive shaft having an input shaft connected to the intermediate shaft and an output shaft connected to drive wheels; an electricity storage device capable of exchanging electric power with the first and second motors; and a shift selection device for selecting one shift range from a plurality of shift ranges including a manual range for approximating the behavior of the engine to the behavior of an engine mounted in a vehicle having the engine and the transmission, the control device being mounted on a vehicle that includes an engine, a first motor, a second motor connected to an intermediate shaft; When the accelerator is released and a reduction process for reducing the required braking torque is executed during the restriction on the fuel cut of the engine, if a restriction release condition for releasing the restriction on the fuel cut of the engine is satisfied and the manual range is selected by the shift selection device, the restriction on the fuel cut of the engine is continued. Control device.

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