JP3714308B2 - Control device for hybrid vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus for a hybrid vehicle that uses both an engine and a motor generator as a vehicle propulsion source, and more particularly to a deceleration control technique during a deceleration coasting operation of the vehicle.
[0002]
[Prior art]
In an engine vehicle that uses only the engine as a vehicle propulsion source, generally, during deceleration coasting of the vehicle, that is, the vehicle required driving force is 0 or a negative value (typically, the accelerator pedal is released, that is, the accelerator While the vehicle is running (when the opening degree is 0) (when the vehicle speed is a value exceeding 0), the engine is stopped, specifically fuel cut (fuel supply stop), and if necessary, the engine A lockup clutch of a torque converter provided in a power transmission path with the drive wheels is fastened, and engine brake torque due to engine friction is applied as vehicle deceleration torque.
[0003]
Further, as disclosed in Japanese Patent Laid-Open No. 2001-112105, in a hybrid vehicle that uses both an engine and a motor generator as a propulsion source for vehicle travel, the motor generator is regenerated during the deceleration coast operation as described above. By applying the regenerative torque as the vehicle deceleration torque by driving, it becomes possible to effectively recover the deceleration energy that was wastedly discharged as the engine brake in the engine vehicle, and the energy efficiency is improved.
[0004]
[Problems to be solved by the invention]
The power that can be regenerated by the motor generator during deceleration coasting corresponds to the target deceleration minus engine friction, vehicle running resistance, etc., and the motor generator rating, battery capacity, and lockup clutch lockup torque Etc. For this reason, for example, when an auxiliary machine such as an air compressor is driven during a deceleration coast operation, if the power consumption from the battery continues to exceed the regenerative power for a long time, the stored value of the battery, that is, the SOC (state Of charge) will eventually decrease, and the SOC of the battery will be excessively small, resulting in an overdischarged state, leading to a decrease in battery performance and the inability to drive auxiliary machinery, etc. There is a risk of hindrance to driving performance.
[0005]
The present invention has been made in view of such problems, and a main object of the present invention is to provide a novel control device for a hybrid vehicle that can stably continue the deceleration coast operation without causing overdischarge of the battery. It is said.
[0006]
[Means for Solving the Problems]
A control apparatus for a hybrid vehicle according to the present invention includes an engine and a motor generator connected to each other as a vehicle propulsion source, and a lock that is provided in a power transmission path between the engine, the motor generator, and drive wheels, and that intermittently connects the power transmission path. An up clutch and drive wheel side rotation speed detecting means for detecting the drive wheel side rotation speed of the lock-up clutch are provided. Then, it is determined whether the vehicle is in the normal deceleration mode or the forced power generation mode during the deceleration coast operation of the vehicle (determination means). When it is determined that the normal deceleration mode is selected, at least the engine is deactivated (normal deceleration means). When the forced power generation mode is determined, the lockup clutch is released, the engine is operated, and the motor generator is controlled to rotate toward the target rotation speed (forced power generation means). The target rotational speed at this time is set in the range below the driving wheel side rotational speed when the driving wheel side rotational speed is equal to or higher than the predetermined idle rotational speed, and preferably when the driving wheel side rotational speed is less than the idle rotational speed. The idling speed is set (target speed setting means).
[0007]
【The invention's effect】
In the normal deceleration mode, since the engine is in an inoperative state, the engine brake torque due to engine friction can be applied to the drive wheels as vehicle braking torque.
[0008]
In the forced power generation mode, a sufficient regenerative torque can be obtained by opening the lock-up clutch, operating the engine, and controlling the rotational speed of the motor generator toward the target rotational speed. Therefore, the deceleration coasting operation can be stably continued without causing overdischarge of the battery.
[0009]
The target rotational speed in the forced power generation mode is set in a range of the driving wheel side rotational speed or less when the driving wheel side rotational speed of the lockup clutch is the idle rotational speed or more. Accordingly, the motor rotation speed is maintained at a state equal to or lower than the rotation speed on the driving wheel side of the lockup clutch, and driving torque that cancels the braking torque is not transmitted from the engine and motor generator side to the driving wheel side, and is reduced. There is no risk of unexpected acceleration during coasting.
[0010]
In the forced power generation mode, the lockup clutch is open, so the target speed of the motor generator can be set from a wide range of rotation speeds below the drive wheel side rotation speed of the lockup clutch. Since a good rotation speed can be set as the target rotation speed, the forced power generation mode can be finished in a short period of time and the normal deceleration mode can be restored.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 schematically shows a power train of a hybrid vehicle to which a control device according to an embodiment of the present invention is applied. This hybrid vehicle uses both an engine 1 and a motor generator 2 as vehicle propulsion sources. The engine 1 is a well-known gasoline engine or diesel engine that generates driving force by burning fuel such as gasoline or light oil. The motor generator 2 is connected to the battery 3 via the inverter 4 and generates a driving force by performing a power running operation with electric power supplied from the battery 3 during motor running or motor assist operation, and during vehicle deceleration or regeneration. By performing regenerative operation, power is regenerated and the battery 3 is charged. The engine 1 and the motor generator 2 are coupled to each other so as to be able to transmit power. In this embodiment, the rotor that is the rotating shaft of the motor generator 2 is directly connected to the crankshaft that is the rotating shaft of the engine 1. Rotates integrally with the crankshaft.
[0012]
The power transmission path connecting the engine 1 and the motor generator 2 and the drive wheels 5 is provided with a torque converter 6 and an automatic transmission 8 equipped with a lockup clutch 7 (see FIG. 2) for intermittently connecting the power transmission path. Has been. As shown in FIG. 2, the lockup clutch 7 switches between engagement and disengagement between the pump impeller 6 a on the engine / motor side of the torque converter 6 and the turbine runner 6 b on the drive wheel side. The automatic transmission 8 may be a stepped automatic transmission having a plurality of planetary gear mechanisms, or may be a continuously variable transmission such as a belt type or a toroidal type.
[0013]
FIG. 2 is a system configuration diagram schematically illustrating a control apparatus for a hybrid vehicle according to the present embodiment. The hybrid controller 11 comprehensively controls the operation of the entire vehicle. Based on various sensors described later, detection signals from the battery controller 12, and the like, an engine controller 13, a motor controller 14, and a speed change (A / T) controller. A command signal or command value is output to 15. These controllers 11 to 15 are CPUs, ROMs, RAMs, input / output interfaces, and the like, and are known microcomputer systems that store and execute various arithmetic / control processes as programs.
[0014]
The engine controller 13 performs engine control such as fuel injection control and ignition timing control based on a command signal (command value) from the hybrid controller 11. The motor controller 14 performs torque control or rotation speed control of the motor generator 2 toward the target torque or target rotation speed as a command value sent from the hybrid controller 11. The shift controller 15 outputs a control signal to the lock-up solenoid 7a of the lock-up clutch 7 to control ON / OFF of the lock-up clutch 7 and outputs a control signal to the shift solenoid 8a of the automatic transmission 8. Then, the shift control of the automatic transmission 8 is performed.
[0015]
As the various sensors, in this vehicle, an engine rotation speed sensor 21 that detects the rotation speed (rotation speed) of the engine 1, a motor rotation speed sensor 22 that detects the rotation speed (rotation speed) of the motor generator 2, and a torque converter. 6 corresponds to a turbine rotation speed sensor (drive wheel side rotation speed detecting means) 23 for detecting the rotation speed of the lockup clutch 7, that is, a driving wheel side rotation speed detecting means 23, a vehicle speed sensor 24 for detecting the vehicle speed, and a vehicle required driving force. An accelerator opening sensor 25 that detects the opening of an accelerator pedal (not shown), a gear position sensor 26 that detects the gear position of the automatic transmission 8, and the like are provided.
[0016]
Based on the voltage value and current value of the battery 3 obtained from the battery voltage sensor 27 and the battery current sensor 28, the battery controller 12 described above stores the storage value (SOC) of the battery 3, the input power and the output power of the battery 3. And the SOC and power that can be input / output are transmitted to the hybrid controller 11.
[0017]
FIG. 3 is a block diagram schematically showing some arithmetic units stored and executed by the hybrid controller 11. The battery state calculation unit 31 calculates the state of the battery 3 based on the SOC of the battery, the input / output power of the battery, the battery temperature, and the like input from the battery controller 12 (and the battery temperature sensor). The power generation amount calculation unit 32 calculates the target power generation amount based on the state of the battery supplied from the battery state calculation unit 31, the turbine rotation speed from the turbine rotation speed sensor 23, the motor rotation speed from the motor rotation speed sensor 22, and the like. While calculating, a coast forced power generation flag is set. As will be described later, for example, the coast forced power generation flag is set when the SOC of the battery is equal to or less than a predetermined power generation request value. Based on the setting state of the coast forced power generation flag, it is determined whether the forced power generation mode or the normal deceleration mode. Is performed (see S2 in FIG. 4). The target engine output calculation unit 33 calculates a target engine output necessary for power generation based on the target power generation amount input from the power generation amount calculation unit 32, and calculates an engine shaft target rotational speed corresponding to the target engine output. .
[0018]
The driving state calculation unit 34 calculates the driving state mode based on the states of the coast forced power generation flag and the idle stop prohibition flag in addition to the detection signals from the various sensors 21 to 26 described above. The idle prohibition flag is set, for example, when the SOC of the battery is less than a predetermined value. The motor generator (MG) command value calculation unit 35 is based on the operation state mode from the operation state calculation unit 34, the engine shaft target rotation number from the target engine output calculation unit 33, and the like. Torque is calculated and output to the motor generator 2 as a command value. The engine command value calculator 36 outputs a fuel cut command signal or a target engine torque command value based on the above-described operation state mode, engine shaft target speed, and the like. The shift (T / M) command value calculation unit 37 sets the engagement flag of the lockup clutch 7 based on the above-described operation state mode, engine shaft target rotational speed, and the like. Based on this engagement flag, the transmission controller 15 performs switching control of engagement / release of the lockup clutch 7.
[0019]
4 and 5 are a flowchart and a time chart showing a characteristic control flow of the present embodiment. The routine in FIG. 4 is executed, for example, every predetermined period (for example, every 10 ms) by the hybrid controller 11.
[0020]
In S (step) 1, it is determined whether or not the vehicle is decelerating and coasting. Specifically, when the vehicle speed detected by the vehicle speed sensor 24 exceeds 0, the vehicle required driving force is 0 or a negative value, specifically, the accelerator opening detected by the accelerator opening sensor 25 is When it is 0 (zero), it is determined that the vehicle is in the deceleration coast operation, and the process proceeds to S2 and subsequent steps. Therefore, for example, when the vehicle is traveling on a steep downhill with the accelerator pedal released, it is determined that the vehicle is decelerating and coasting even if the vehicle speed gradually increases. If it is determined that the vehicle is not decelerating coasting, this routine is terminated.
[0021]
In S2, it is determined whether the normal deceleration mode M1 or the forced power generation mode M2 based on the vehicle operating state. In this embodiment, the determination of S2 is performed based on the SOC of the battery 3 corresponding to the power generation request. For example, as shown in FIG. 5, when the SOC of the battery 3 becomes equal to or lower than a predetermined power generation request value L during operation in the normal deceleration mode M1, the mode shifts to the forced power generation mode M2. Although not shown in FIG. 3, a predetermined hysteresis is given to the determination of S2 so that the operation switching between the normal deceleration mode M1 and the forced power generation mode M2 is not excessively performed. That is, the SOC threshold value of the battery 3 when shifting from the forced power generation mode M2 to the normal deceleration mode M1 is set to a value higher than the power generation request value L.
[0022]
During operation in the normal deceleration mode M1, the SOC consumed gradually by driving auxiliary equipment such as an air compressor is larger than the regenerative power, that is, the SOC gradually decreases as shown in A1 of FIG. When the going situation continues for a predetermined period, the determination in S2 may be switched from the normal deceleration mode M1 to the forced power generation mode M2.
[0023]
S3 to S6 indicate the processing contents when it is determined that the normal deceleration mode M1 is determined in S2 (normal deceleration means). In S3, the lockup clutch 7 is engaged. Alternatively, in the normal deceleration mode M1, engagement / release of the lockup clutch 7 may be switched according to the vehicle speed or the like. In S4, the fuel cut (fuel supply stop) of the engine 1 is performed, and the engine 1 is brought into a non-operating state. As a result, engine brake torque due to engine friction acts as vehicle deceleration torque. In S5, the target regenerative torque of the motor generator 2 is calculated. This target regenerative torque corresponds to a value obtained by subtracting the engine brake torque from the vehicle required deceleration torque. In S6, this target regenerative torque is output to the motor controller 14 as a command value. The motor controller 14 that has received the command controls the torque of the motor generator 2 toward the target regeneration torque.
[0024]
S11 to S18 indicate processing contents when it is determined that the forced power generation mode M2 is determined in S2 (forced power generation means). In S11 and S12, if the lock-up clutch 7 is engaged, the lock-up clutch 7 is released. In S13, a fuel cut recovery command signal of the engine 1 is output. That is, the fuel cut of the engine 1 is stopped, fuel injection is restarted, and the engine 1 is put into an operating state.
[0025]
In subsequent S14 to S16, the target rotational speed of the motor generator 2 is set (target rotational speed setting means). When the turbine rotation speed detected by the turbine rotation speed sensor 23, that is, the drive wheel side rotation speed of the lockup clutch is equal to or higher than a predetermined idle rotation speed set in advance, the process proceeds from S14 to S15 and the target of the motor generator 2 is reached. The rotational speed is set so that the power generation efficiency of the motor generator 2 is as high as possible within the range of the turbine rotational speed or less. When the turbine rotational speed is less than the idle rotational speed, the process proceeds from S14 to S16, and the idle rotational speed is set as the target rotational speed of the motor generator 2.
[0026]
In S17, the target rotation speed set in S15 or S16 is output to the battery controller 12 as a command value. Receiving the command, the battery controller 12 controls the rotational speed of the motor generator 2 toward the target rotational speed. In S18, the power generation torque of the engine is set based on the target rotational speed of the motor generator 2, and the power generation torque is output to the engine controller 13 as a command value. Upon receiving the command, the engine controller 13 adjusts the fuel injection amount based on the power generation torque.
[0027]
According to the present embodiment as described above, in the normal deceleration mode M1, the engine 1 is fuel cut and the motor generator 2 is regeneratively operated, so that the engine brake torque due to engine friction and the regenerative torque due to the motor generator 2 are reduced. Vehicle braking torque can be sufficiently applied to the drive wheel 5 side, fuel efficiency can be improved by fuel cut, and energy efficiency can be improved by regenerative operation of the motor generator 2.
[0028]
Further, when the lockup clutch 7 is engaged, the engine 1, the motor generator 2, and the drive wheel 5 side are substantially directly connected without passing through the torque converter 6, and a loss due to slippage of the torque converter 6 is caused. Instead, the engine brake torque and the regenerative torque can be transmitted to the drive wheel 5 side as a braking torque.
[0029]
In the forced power generation mode M2, the lockup clutch 7 is released, the direct connection state between the engine 1 and the motor generator 2 and the drive wheel 5 side is released, the engine 1 is put into the operating state, and the motor generator 2 is rotated at the target rotation. The number of revolutions is controlled toward the number. Therefore, in a situation where auxiliary equipment such as an air compressor is being driven during the deceleration coast operation, that is, in a situation where the SOC of the battery 3 gradually decreases, the forced power generation mode M2 is performed, so that the battery Thus, it is possible to stably continue the deceleration coasting operation while preventing excessive discharge.
[0030]
As shown in S14 and S15, the target rotational speed in the forced power generation mode M2 is set within a range of the turbine rotational speed or lower when the turbine rotational speed (the rotational speed on the drive wheel side of the lockup clutch) is higher than the idle rotational speed. The Accordingly, the motor rotation speed (engine / motor side rotation speed of the lockup clutch 7) is maintained at a state equal to or lower than the drive wheel side rotation speed of the lockup clutch 7, and the driving torque that cancels the braking torque is the engine 1 and the motor. There is no transmission from the generator 2 side to the drive wheel 5 side, and there is no possibility of giving an unexpected feeling of acceleration or the like during the deceleration coast operation. In addition, the target rotational speed of the motor generator 2 can be set from a wide rotational speed range equal to or lower than the turbine rotational speed, and a rotational speed with good power generation efficiency can be set as the target rotational speed. The forced power generation mode M2 can be terminated and the normal deceleration mode M1 can be restored.
[0031]
As shown in S14 and S16, the target rotational speed in the forced power generation mode M2 is set to the idle rotational speed when the turbine-side rotational speed is lower than the idle rotational speed. Therefore, a predetermined creep force is transmitted from the engine 1 and motor generator 2 side to the drive wheel 5 side via the torque converter 6, and the engine speed does not become lower than the idle speed. The next engine restart can be performed promptly.
[0032]
If the motor generator is torque-controlled toward the target regenerative torque with the lock-up clutch released, there is a problem that the vehicle does not smoothly decelerate, but when the motor generator is controlled in rotation speed as in this embodiment, The vehicle can be smoothly decelerated via the torque converter 6.
[0033]
As described above, the present invention has been described based on the specific embodiments. However, the present invention is not limited to the above embodiments, and includes various modifications and changes. For example, the present invention can be applied to a hybrid vehicle having a power train as shown in FIG. Here, the crankshaft that is the rotation shaft of the engine 1 and the rotor that is the rotation shaft of the motor generator 2 are connected via a winding conduction mechanism including a conduction belt 43 wound around the crank pulley 41 and the motor pulley 42. ing. In FIG. 6, 45 is an air compressor as an auxiliary machine, 46 is a pulley 46 for an air compressor around which a conductive belt 43 is wound, 47 is a clutch for intermittently transmitting power between the main body of the compressor 45 and the pulley 46, 48 The crank pulley clutches 48 and 49 for intermittently transmitting power between the main body of the engine 1 and the crank pulley 41 are connected to the crank shaft of the engine 1 via gears 50 and 51, and are crankers for cranking the crank shaft.
[0034]
In addition, instead of directly detecting the rotational speed of the drive wheel side of the lockup clutch 7 by the turbine rotational speed sensor 23 as in the above embodiment, the rotational speed is estimated from the vehicle speed, the gear ratio of the automatic transmission 8, and the like. Anyway.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a powertrain of a hybrid vehicle according to an embodiment of the present invention.
FIG. 2 is a system configuration diagram showing a control apparatus for a hybrid vehicle according to the embodiment.
FIG. 3 is a calculation block diagram of a control device according to the present embodiment.
FIG. 4 is a flowchart showing a control flow according to the embodiment.
FIG. 5 is a time chart showing an aspect of transition from a normal deceleration mode to a forced deceleration mode during vehicle deceleration coast operation.
FIG. 6 is a block diagram schematically showing another example of a powertrain of a hybrid vehicle according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator 3 ... Battery 6 ... Torque converter 7 ... Lock-up clutch 23 ... Turbine rotational speed sensor (drive wheel side rotational speed detection means)

Claims (6)

An engine and a motor generator connected to each other as a vehicle propulsion source, a lockup clutch that is provided in a power transmission path between the engine, the motor generator, and a drive wheel, and that interrupts the power transmission path, and a drive wheel of the lockup clutch In a control device for a hybrid vehicle having drive wheel side rotation speed detection means for detecting a side rotation speed,
Determining means for determining whether the vehicle is in a normal deceleration mode or a forced power generation mode during deceleration coasting of the vehicle;
Normal deceleration means for at least deactivating the engine when the normal deceleration mode is determined;
When it is determined that the forced power generation mode, forced power generation means for releasing the lock-up clutch, setting the engine in an operating state, and controlling the rotational speed of the motor generator toward a target rotational speed;
Target rotational speed setting means for setting the target rotational speed within a range equal to or lower than the driving wheel side rotational speed when the forced power generation mode is set and the driving wheel side rotational speed is equal to or higher than a predetermined idle rotational speed. When,
A control apparatus for a hybrid vehicle, comprising: The target rotational speed setting means sets the target rotational speed to an idle rotational speed in the forced power generation mode and when the drive wheel side rotational speed is less than the idle rotational speed. The vehicle control device according to claim 1. When it is determined that the normal deceleration mode is selected, the normal deceleration means engages the lockup clutch, sets a target regenerative torque of the motor generator, and torque-controls the motor generator toward the target regenerative torque. The hybrid vehicle control device according to claim 1 or 2, wherein the control device is a hybrid vehicle control device. A battery for supplying electric power to the motor generator and storing electric power supplied from the motor generator;
The determination means determines that the forced power generation mode is set when the stored value of the battery is equal to or lower than a predetermined power generation request value, and the normal deceleration mode when the stored power value of the battery exceeds the predetermined power generation request value. The hybrid vehicle control device according to claim 1, wherein the control device determines that the vehicle is a hybrid vehicle. 5. The vehicle control device according to claim 1, wherein the rotation shaft of the motor generator is directly connected to the rotation shaft of the engine and rotates integrally with the rotation shaft of the engine. 5. The vehicle control device according to claim 1, wherein the rotation shaft of the motor generator is connected to the rotation shaft of the engine via a winding conduction mechanism.

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