JP2012086769A - Control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately protect a second clutch which connects or disconnects a motor generator and a drive wheel.SOLUTION: A control device for hybrid vehicle which has an internal combustion 10, the motor generator 20, a first clutch 15 which is disposed between the internal combustion and the motor generator and which connects or disconnects the internal combustion and the motor generator, and the second clutch 25 which is disposed between the motor generator and the drive wheel and which connects or disconnects the motor generator and the drive wheel, further has a temperature detecting means that detects a temperature of the second clutch, a stall-stop state determining means that determines a stall-stop state, a clutch protection control means that performs clutch protection control for engaging both the first clutch and the second clutch when it is determined that a state is the stall-stop state and the temperature of the second clutch is equal to or higher than predetermined temperature, and a start restricting means that restricts start of the internal combustion when the clutch protection control is performed and the drive wheel is not locked.

Description

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

  There is known a hybrid vehicle including an internal combustion engine, a motor generator, a first clutch that connects and disconnects the internal combustion engine and the motor generator, and a second clutch that connects and disconnects the motor generator and a drive wheel. In such a hybrid vehicle, on the uphill road, when the driver is in a stall stop state where the driver adjusts the accelerator pedal and maintains the vehicle stop state, and the temperature of the second clutch is equal to or higher than a predetermined temperature, the first clutch, A technique for performing clutch protection control for engaging both the second clutch and the second clutch is known (see, for example, Patent Document 1).

JP 2010-149649 A

  In addition, when releasing the clutch protection control after performing the clutch protection control as described above, the SOC of the battery mounted on the hybrid vehicle is less than a predetermined value, and it is impossible to run only with the motor generator. For this, it is necessary to start the internal combustion engine and to bring the second clutch into a slip state. However, if the internal combustion engine is started in a state where the temperature of the second clutch is not sufficiently lowered, and the second clutch is brought into the slip state, the temperature of the second clutch becomes the predetermined temperature or more again, As a result, there is a problem that the clutch protection control is performed again.

  The problem to be solved by the present invention is to provide a control device for a hybrid vehicle that can appropriately release the clutch protection control for protecting the second clutch that connects and disconnects the motor generator and the drive wheel. .

  The present invention provides a first clutch for connecting / disconnecting an internal combustion engine and a motor generator when the stall clutch is stopped and the temperature of the second clutch for connecting / disconnecting the motor generator and drive wheels is equal to or higher than a predetermined temperature. The above-described problem is solved by performing clutch protection control for engaging the two clutches together and prohibiting the start of the internal combustion engine when the drive wheels are not locked during the clutch protection control.

  According to the present invention, when the driving wheel is not locked, the internal combustion engine is prohibited from starting by starting the internal combustion engine in a state where the temperature of the second clutch is not sufficiently lowered. Thus, it is possible to avoid a state in which the temperature of the second clutch becomes equal to or higher than the predetermined temperature again and the clutch protection control is performed again, and thus the clutch protection control can be appropriately released. .

FIG. 1 is a block diagram showing the overall configuration of the hybrid vehicle according to the present embodiment. FIG. 2 is a diagram illustrating a power train of a hybrid vehicle according to another embodiment. FIG. 3 is a diagram illustrating a power train of a hybrid vehicle according to another embodiment. FIG. 4 is a skeleton diagram showing the configuration of the automatic transmission according to the present embodiment. FIG. 5 is a diagram showing a shift map. FIG. 6 is a control block diagram of the integrated control unit 60. FIG. 7 is a diagram illustrating an example of the target driving force map. FIG. 8 is a schematic diagram showing the selection logic of the mode map. FIG. 9 is a diagram showing a normal mode map. FIG. 10 is a diagram showing a MWSC compatible mode map. FIG. 11 is a diagram illustrating an example of a target charge / discharge amount map. FIG. 12 is a schematic diagram illustrating an engine operating point setting process in the WSC traveling mode. FIG. 13 is a map showing the target engine speed in the WSC travel mode. FIG. 14 is a time chart showing changes in the engine speed when the vehicle speed is increased in a predetermined state. FIG. 15 is a flowchart showing a flow of switching processing for switching from the clutch protection control mode to the normal control mode. FIG. 16 is a time chart showing clutch protection control according to the present embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of the hybrid vehicle according to the present embodiment.

  The hybrid vehicle 1 according to the present embodiment is a parallel electric vehicle that uses a plurality of power sources for driving the vehicle. As shown in FIG. 1, the hybrid vehicle 1 includes an internal combustion engine (hereinafter referred to as “engine”) 10, a first clutch 15, a motor generator (electric motor / generator) 20, a second clutch 25, a battery 30, and an inverter 35. And an automatic transmission 40, a propeller shaft 51, a differential gear unit 52, a drive shaft 53, and left and right drive wheels 54.

  The engine 10 is an internal combustion engine that operates using gasoline or light oil as fuel, and based on a control signal from the engine control unit 70, the valve opening of the throttle valve, the fuel injection amount, and the like are controlled.

  First clutch 15 is interposed between the output shaft of engine 10 and the rotation shaft of motor generator 20, and connects and disconnects power transmission between engine 10 and motor generator 20. As a specific example of the first clutch 15, for example, a wet multi-plate clutch capable of continuously controlling the oil flow rate and hydraulic pressure with a proportional solenoid can be exemplified. The first clutch 15 controls the hydraulic pressure of the hydraulic unit 16 based on a control signal from the integrated control unit 60, thereby engaging / disengaging the clutch plate (including a slip state).

  The motor generator 20 is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator. The motor generator 20 is provided with a resolver 21 that detects a rotor rotation angle. The motor generator 20 functions not only as an electric motor but also as a generator. When three-phase AC power is supplied from the inverter 35, the motor generator 20 is driven to rotate (powering). On the other hand, when the rotor is rotated by an external force, motor generator 20 generates AC power by generating electromotive force at both ends of the stator coil (regeneration). The AC power generated by the motor generator 20 is converted into DC power by the inverter 35 and then charged to the battery 30.

  Specific examples of the battery 30 include a lithium ion secondary battery and a nickel hydride secondary battery. A current / voltage sensor 31 is attached to the battery 30, and these detection results can be output to the motor control unit 80.

  The second clutch 25 is interposed between the motor generator 20 and the left and right drive wheels 54, and connects and disconnects power transmission between the motor generator 20 and the left and right drive wheels 54. As a specific example of the second clutch 25, for example, a wet multi-plate clutch can be exemplified as in the case of the first clutch 15 described above. The second clutch 25 engages / disengages the clutch plate (including a slip state) by controlling the hydraulic pressure of the hydraulic unit 26 based on a control signal from the transmission control unit 90.

  The automatic transmission 40 is a transmission that automatically switches the stepped gear ratio such as the seventh forward speed and the first reverse speed according to the vehicle speed, the accelerator opening degree, and the like. The automatic transmission 40 changes the gear ratio based on a control signal from the transmission control unit 90. As shown in FIG. 1, the second clutch 25 does not need to be newly added as a dedicated clutch, and includes a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission 40. A number of frictional engagement elements can be used. However, the configuration is not particularly limited, and for example, as shown in FIG. 2, the second clutch 25 is interposed between the output shaft of the motor generator 20 and the input shaft of the automatic transmission 40. Alternatively, as shown in FIG. 3, the second clutch 25 may be interposed between the output shaft of the automatic transmission 40 and the propeller shaft 51. 2 and 3 are diagrams showing the configuration of a hybrid vehicle according to another embodiment. In FIGS. 2 and 3, the configuration other than the power train is the same as that in FIG. Is shown. 1 to 3 exemplify a rear-wheel drive hybrid vehicle, it is of course possible to use a front-wheel drive hybrid vehicle or a four-wheel drive hybrid vehicle.

  FIG. 4 is a skeleton diagram showing the configuration of the automatic transmission 40. The automatic transmission 40 includes a first planetary gear set GS1 (first planetary gear G1, second planetary gear G2) and a second planetary gear set GS2 (third planetary gear G3, fourth planetary gear G4). The first planetary gear set GS1 (first planetary gear G1, second planetary gear G2) and the second planetary gear set GS2 (third planetary gear G3, fourth planetary gear G4) are output in the axial direction from the input shaft Input side. They are arranged in this order toward the axis Output side.

  The automatic transmission 40 also includes a plurality of clutches C1, C2, C3, a plurality of brakes B1, B2, B3, B4 and a plurality of one-way clutches F1, F2 as friction engagement elements.

  The first planetary gear G1 is a single pinion planetary gear having a first sun gear S1, a first ring gear R1, and a first carrier PC1 that supports a first pinion P1 that meshes with both the gears S1 and R1. The second planetary gear G2 is a single pinion type planetary gear having a second sun gear S2, a second ring gear R2, and a second carrier PC2 that supports a second pinion P2 that meshes with both the gears S2 and R2. The third planetary gear G3 is a single pinion planetary gear having a third sun gear S3, a third ring gear R3, and a third carrier PC3 that supports a third pinion P3 that meshes with both the gears S3 and R3. is there. Further, the fourth planetary gear G4 is a single pinion planetary gear having a fourth sun gear S4, a fourth ring gear R4, and a fourth carrier PC4 that supports the fourth pinion P4 meshing with both the gears S4 and R4. is there.

  The input shaft Input is connected to the second ring gear R2 and inputs the rotational driving force from the engine 10. The output shaft Output is connected to the third carrier PC3, and transmits the output rotational driving force to the driving wheels 54 via a final gear (not shown) or the like. The first connecting member M1 is a member that integrally connects the first ring gear R1, the second carrier PC2, and the fourth ring gear R4. The second connecting member M2 is a member that integrally connects the third ring gear R3 and the fourth carrier PC4. The third connecting member M3 is a member that integrally connects the first sun gear S1 and the second sun gear S2.

  The first planetary gear set GS1 is formed by connecting a first planetary gear G1 and a second planetary gear G2 by a first connecting member M1 and a third connecting member M3, and is composed of four rotating elements. Further, the second planetary gear set GS2 is formed by connecting the third planetary gear G3 and the fourth planetary gear G4 by the second connecting member M2, and is composed of five rotating elements. The first planetary gear set GS1 has a torque input path that is input from the input shaft Input to the second ring gear R2. The torque input to the first planetary gear set GS1 is output from the first connecting member M1 to the second planetary gear set GS2. The second planetary gear set GS2 has a torque input path that is input from the input shaft Input to the second connecting member M2, and a torque input path that is input from the first connecting member M1 to the fourth ring gear R4. The torque input to the second planetary gear set GS2 is output from the third carrier PC3 to the output shaft Output.

  Note that when the H & LR clutch C3 is released and the rotation speed of the fourth sun gear S4 is larger than that of the third sun gear S3, the third sun gear S3 and the fourth sun gear S4 generate independent rotation speeds. Therefore, the third planetary gear G3 and the fourth planetary gear G4 are connected via the second connecting member M2, and each planetary gear achieves an independent gear ratio.

  The input clutch C1 is a clutch that selectively connects and disconnects the input shaft Input and the second connecting member M2. The direct clutch C2 is a clutch that selectively connects and disconnects the fourth sun gear S4 and the fourth carrier PC4. The H & LR clutch C3 is a clutch that selectively connects and disconnects the third sun gear S3 and the fourth sun gear S4. A second one-way clutch F2 is arranged between the third sun gear S3 and the fourth sun gear S4. The front brake B1 is a brake that selectively stops the rotation of the first carrier PC1. The first one-way clutch F1 is disposed in parallel with the front brake B1. The low brake B2 is a brake that selectively stops the rotation of the third sun gear S3. The 2346 brake B3 is a brake that selectively stops the rotation of the third connecting member M3 (the first sun gear S1 and the second sun gear S2). The reverse brake B4 is a brake that selectively stops the rotation of the fourth carrier PC4.

  FIG. 5 is a diagram showing a fastening operation table for the seventh forward speed and the first reverse speed in the automatic transmission 40. In FIG. 5, “◯” indicates a state in which the corresponding clutch or brake is engaged, and a blank indicates a state in which these are released. In FIG. 5, “(◯)” indicates that the engine is engaged only when the engine brake is applied. As described above, in this embodiment, the frictional engagement element in the automatic transmission 40 is used as the second clutch 25, and the frictional engagement element surrounded by the thick solid line in FIG. The clutch 25 can be used. Specifically, the low brake B2 corresponds to the second clutch 25 from the first speed to the third speed, and the H & LR clutch C3 corresponds to the second clutch 25 from the fourth speed to the seventh speed.

  The automatic transmission 40 is not particularly limited to the above-described stepped transmission of the seventh forward speed and the first reverse speed. For example, the fifth forward speed as described in Japanese Patent Application Laid-Open No. 2007-314097, A stepped transmission with a first reverse speed may be used as the automatic transmission 40.

  Returning to FIG. 1, the output shaft of the automatic transmission 40 is connected to the left and right drive wheels 54 via a propeller shaft 51, a differential gear unit 52, and left and right drive shafts 53. In FIG. 1, reference numeral 55 denotes left and right steering front wheels.

  The hybrid vehicle 1 in the present embodiment can be switched to each travel mode described below according to the engaged / released state of the first and second clutches 15 and 25.

  The motor use travel mode (hereinafter referred to as “EV travel mode”) is a mode in which the first clutch 15 is disengaged and the second clutch 25 is engaged to travel using only the power of the motor generator 20 as a power source. .

  The engine use travel mode (hereinafter referred to as “HEV travel mode”) is a mode in which both the first clutch 15 and the second clutch 25 are engaged and the engine 10 is included in the power source.

  The engine use slip traveling mode (hereinafter referred to as “WSC traveling mode”) is a mode in which the first clutch 15 is engaged and the second clutch 25 is in a slip state and the engine 10 is included in the power source and travels. . This WSC travel mode is a mode for achieving creep travel, particularly when the state of charge (SOC) of the battery 30 is lowered or when the temperature of the cooling water of the engine 10 is low. Details of the WSC travel mode will be described later.

  In the motor use slip running mode (hereinafter referred to as “MWSC running mode”), the first clutch 15 is disengaged while the engine 10 is operated, and the second clutch 25 is brought into the slip state, so that the motor generator 20 In this mode, only power is used as a power source. In particular, in the above-described WSC travel mode, when the road surface slope is an uphill road having a predetermined value or more, a state in which the driver adjusts the accelerator pedal and maintains the vehicle stop state or the slow start state, so-called stall stop state continues. Then, the state in which the slip amount of the second clutch 25 is excessive continues, so that the second clutch 25 may be overheated. This is because engine stall occurs when the engine speed is made lower than the idle speed. Therefore, in this embodiment, in such a case, the MWSC traveling mode is selected in order to prevent the second clutch 25 from being overheated. Details of the MWSC travel mode will be described later.

  When shifting from the EV travel mode to the HEV travel mode, the engine can be started by engaging the released first clutch 15 and using the torque of the motor generator 20.

  HEV travel modes include an engine travel mode, a motor assist travel mode, and a travel power generation mode. In the engine running mode, the drive wheel 54 is moved using only the engine 10 as a power source without driving the motor generator 20. In the motor assist travel mode, both the engine 10 and the motor generator 20 are driven, and the drive wheels 54 are moved using these two as power sources. In the traveling power generation mode, the drive wheel 54 is moved using the engine 10 as a power source, and at the same time, the motor generator 20 is caused to function as a generator to charge the battery 30.

  In addition to the modes described above, there is a power generation mode for charging the battery 30 and supplying power to the electrical components by causing the motor generator 20 to function as a generator using the power of the engine 10 when the vehicle is stopped. May be.

  The control system of the hybrid vehicle 1 in this embodiment includes an integrated control unit 60, an engine control unit 70, a motor control unit 80, and a transmission control unit 90, as shown in FIG. These control units 60, 70, 80, and 90 are connected to each other through, for example, CAN communication.

  The engine control unit 70 outputs a command for controlling an engine operating point (engine speed Ne, engine torque Te) to a throttle valve actuator provided in the engine 10 in accordance with a target engine torque command or the like from the integrated control unit 60. To do. Information on the engine speed Ne and the engine torque Te is supplied to the integrated control unit 60 via the CAN communication line.

  The motor control unit 80 inputs information from the resolver 21 provided in the motor generator 20, and according to the target motor generator torque command value from the integrated control unit 60, the operating point of the motor generator 20 (motor rotation speed Nm). , A command for controlling the motor torque Tm) is output to the inverter 35. The motor control unit 80 calculates and manages the SOC of the battery 30 based on the current value and the voltage value detected by the current / voltage sensor 31. The SOC information of the battery 30 is used as control information for the motor generator 20 and is sent to the integrated control unit 60 via CAN communication. Furthermore, the motor control unit 80 estimates the motor generator torque Tm based on the value of the current flowing through the motor generator 20 (the driving torque and the regenerative control torque are distinguished based on whether the current value is positive or negative). Information on the motor rotation speed Nm and the motor torque Tm is sent to the integrated control unit 60 via CAN communication.

  The transmission control unit 90 inputs sensor information from an accelerator opening sensor 91, a vehicle speed sensor 92, a second clutch hydraulic pressure sensor 93, and an inhibitor switch 94 that outputs a signal corresponding to the position of the shift lever operated by the driver. In response to the second clutch control command from the integrated control unit 60, a command for controlling the engagement / release of the second clutch 25 is output to the hydraulic unit 26. Information on the accelerator opening APO, the vehicle speed VSP, and the inhibitor switch 94 is sent to the integrated control unit 60 via CAN communication.

  The integrated control unit 60 manages the energy consumption of the entire hybrid vehicle 1 and thus has a function for causing the hybrid vehicle 1 to travel efficiently. The integrated control unit 60 includes a second clutch output rotational speed sensor 61 that detects a second clutch output rotational speed N2out, a second clutch torque sensor 62 that detects a second clutch transmission torque capacity TCL2, a brake hydraulic pressure sensor 63, a second Sensor information is acquired from the temperature sensor 64 that detects the temperature of the clutch 25 and the G sensor 65 that detects the longitudinal acceleration and lateral acceleration of the vehicle. The integrated control unit 60 also acquires sensor information obtained through CAN communication in addition to these pieces of information. As described above, since the second clutch 25 has two types (low brake B2 and H & LR clutch C3) according to the gear position of the automatic transmission 40, the temperature sensor 64 detects these temperatures, respectively. A plurality can be provided as possible.

  Based on these pieces of information, the integrated control unit 60 controls the operation of the engine 10 according to the control command to the engine control unit 70, the operation control of the motor generator 20 based on the control command to the motor control unit 80, and the transmission control unit 90. Control of the automatic transmission 40 according to the control command for the first clutch 15, engagement / release control of the first clutch 15 according to the control command for the hydraulic unit 16 of the first clutch 15, and control command for the hydraulic unit 26 of the second clutch 25 The second clutch 25 is engaged and disengaged by the control.

  Next, the control executed by the integrated control unit 60 will be described. FIG. 6 is a control block diagram of the integrated control unit 60. Note that the control described below is executed every 10 msec, for example. As shown in FIG. 6, the integrated control unit 60 includes a target driving force calculation unit 100, a mode selection unit 200, a target charge / discharge calculation unit 300, an operating point command unit 400, and a shift control unit 500.

  The target driving force calculation unit 100 uses the predetermined target driving force map to perform target driving based on the accelerator opening APO detected by the accelerator opening sensor 91 and the vehicle speed VSP detected by the vehicle speed sensor 92. The force tFo0 is calculated. FIG. 7 shows an example of the target driving force map.

  The mode selection unit 200 includes a road surface gradient estimation calculation unit 210 that estimates a road surface gradient based on the detection value of the G sensor 65. The road surface gradient estimation calculation unit 210 calculates an actual acceleration from a wheel speed acceleration average value or the like of a wheel speed sensor (not shown), and estimates a road surface gradient from a deviation between the calculation result and a detection value of the G sensor 65.

  Further, the mode selection unit 200 has a mode map selection unit 220. Based on the road surface gradient estimated by the road surface gradient estimation calculation unit 210, the mode map selection unit 220 selects which mode map to use from a normal mode map and a MWSC compatible mode map described later. FIG. 8 is a schematic diagram showing selection logic by the mode map selection unit 220. As shown in FIG. 8, the mode map selection unit 220 switches to the MWSC compatible mode map when the estimated gradient is equal to or greater than a predetermined value g2 in a state where the normal mode map is selected. On the other hand, when the estimated gradient is less than the predetermined value g1 (<g2) in the state where the MWSC compatible mode map is selected, the mode is switched to the normal mode map. In other words, the mode selection unit 200 switches the map by providing hysteresis to the estimated gradient, thereby preventing control hunting during map switching.

  Next, the mode map will be described. The mode map includes a normal mode map shown in FIG. 9 and a MWSC compatible mode map shown in FIG.

  As shown in FIG. 9, when the normal mode map is selected, the target mode is selected from the EV travel mode, the WSC travel mode, and the HEV travel mode based on the accelerator opening APO and the vehicle speed VSP. Is done. However, even when the EV travel mode is selected based on the normal mode map, if the SOC of the battery 30 is equal to or lower than the predetermined value, the HEV mode is set as the target mode instead of the EV travel mode.

  In the normal mode map shown in FIG. 9, the HEV → WSC switching line indicates that the rotation speed is smaller than the idling speed of the engine 10 when the automatic transmission 40 is in the first speed in the region below the predetermined accelerator opening APO1. Is set to be in the WSC traveling mode in a region lower than the lower limit vehicle speed VSP1. Further, since a large driving force is required in a region where the accelerator opening APO1 is greater than or equal to, the WSC travel mode is set up to a vehicle speed VSP1 'region that is higher than the lower limit vehicle speed VSP1. When the SOC of the battery 30 is low and the EV travel mode cannot be achieved, the WSC travel mode is selected even when starting.

  Also, as shown in FIG. 10, when the MWSC compatible mode map is selected, the target is selected from the WSC travel mode, the MWSC travel mode, and the HEV travel mode based on the accelerator opening APO and the vehicle speed VSP. A mode is selected. As shown in FIG. 10, the MWSC compatible mode map is different from the normal mode map in that the EV travel mode area is not set. Further, the HEV → WSC switching line is different from the normal mode map in that it is defined only by the lower limit vehicle speed VSP1. Furthermore, it differs from the normal mode map in that the MWSC travel mode area is set in the WSC travel mode area. The MWSC travel mode region is set in a region surrounded by a predetermined vehicle speed VSP2 lower than the lower limit vehicle speed VSP1 and a predetermined accelerator opening APO2 higher than the predetermined accelerator opening APO1.

  Target charge / discharge calculation unit 300 calculates target charge / discharge power tP from the SOC of battery 30 using a predetermined target charge / discharge amount map. FIG. 11 shows an example of the target charge / discharge amount map.

  Based on the accelerator opening APO, the target driving force tFoO, the target mode, the vehicle speed VSP, and the target charging / discharging power tP, the operating point command unit 400 uses the target engine torque, target motor, The generator torque, the target second clutch transmission torque capacity, the target gear position of the automatic transmission 40, and the first clutch solenoid current command are calculated.

  The shift control unit 500 drives and controls the solenoid valve in the automatic transmission 40 so as to achieve the target second clutch transmission torque capacity and the target shift speed according to the shift schedule shown in the shift map. Note that the shift map used at this time is one in which a target gear position is set in advance based on the vehicle speed VSP and the accelerator opening APO.

Next, the WSC travel mode will be described.
The WSC traveling mode is characterized in that the engine 10 is maintained in an operating state, and is a mode having high responsiveness to a required driving force change. Specifically, in the WSC travel mode, the first clutch 15 is completely engaged, the second clutch 25 is slip-controlled as a transmission torque capacity according to the required driving force, and at least one of the engine 10 and the motor generator 20 is controlled. Travel using driving force.

  Since the hybrid vehicle 1 of this embodiment does not have an element that absorbs the difference in rotational speed unlike a torque converter, when the first clutch 15 and the second clutch 25 are completely engaged, the vehicle speed depends on the rotational speed of the engine 10. Will be decided. The engine 10 has a lower limit value based on the idling engine speed for maintaining the self-sustaining rotation. The idling engine speed further increases when the engine is idling up by warming up the engine or the like. Further, in a state where the required driving force is high, there may be a case where the HEV traveling mode cannot be quickly changed.

  On the other hand, in the EV traveling mode, since the first clutch 15 is released, there is no restriction associated with the lower limit value due to the engine speed. However, in the case where it is difficult to travel in the EV travel mode due to the restriction based on the SOC of the battery 30 or in a region where the required driving force cannot be achieved only by the motor generator 20, there is no means other than generating stable torque by the engine 10.

  Therefore, in the present embodiment, in a vehicle speed region lower than the vehicle speed corresponding to the lower limit value and when traveling in the EV traveling mode is difficult, or in a region where the required driving force cannot be achieved only by the motor generator 20, The engine speed is maintained at a predetermined lower limit speed, the second clutch 25 is slip-controlled, and the WSC travel mode for traveling using the engine torque is selected.

  FIG. 12 is a schematic diagram showing the engine operating point setting process in the WSC running mode, and FIG. 13 is a map showing the engine target speed in the WSC running mode. When the driver operates the accelerator pedal in the WSC travel mode, the target engine speed characteristic corresponding to the accelerator pedal opening is selected based on FIG. 13, and the target engine speed corresponding to the vehicle speed is set along this characteristic. The Then, the target engine torque corresponding to the target engine speed is calculated by the engine operating point setting process shown in FIG.

  Here, the operating point of the engine 10 is defined as a point defined by the engine speed and the engine torque. As shown in FIG. 12, it is desirable that the engine operating point be operated on a line (hereinafter referred to as “α line”) connecting operating points with high output efficiency of the engine 10. On the other hand, when the engine speed is set as described above, an operating point away from the α line is selected depending on the accelerator pedal operation amount (required driving force) of the driver. Therefore, in order to bring the engine operating point closer to the α line, the target engine torque is feedforward controlled to a value that takes the α line into consideration.

  On the other hand, the motor generator 20 executes the rotational speed feedback control with the set engine speed as the target rotational speed. Since the engine 10 and the motor generator 20 are in a directly connected state, the motor generator 20 is controlled so as to maintain the target rotational speed, so that the rotational speed of the engine 10 is also automatically feedback-controlled. It will be.

  At this time, the torque output from the motor generator 20 is automatically controlled so as to fill the deviation between the target engine torque determined in consideration of the α-ray and the required driving force. In the motor generator 20, a basic torque control amount (regeneration / power running) is given so as to fill the deviation, and further feedback control is performed so as to coincide with the target engine speed.

  When the required driving force is smaller than the driving force on the α line at a certain engine speed, the engine output efficiency increases as the engine output torque is increased. At this time, by collecting the energy corresponding to the increased output by the motor generator 20, efficient power generation can be performed while the torque itself input to the second clutch 25 is set to the torque required by the driver.

  However, since the upper limit of torque that can be generated is determined by the SOC state of the battery 30, the required power generation output (SOC required power generation power) from the SOC of the battery 30, the torque at the current operating point, and the torque on the α line It is necessary to consider the magnitude relationship with the deviation (α-ray generated power).

  FIG. 12A is a schematic diagram when the α-ray generated power is larger than the SOC required generated power. Since the engine output torque cannot be increased above the SOC required generated power, the operating point cannot be moved on the α line. However, fuel efficiency is improved by moving to a more efficient point.

  FIG. 12B is a schematic diagram when the α-ray generated power is smaller than the SOC required generated power. Since the engine operating point can be moved on the α line within the range of the SOC required generated power, in this case, it is possible to generate power while maintaining the operating point with the highest fuel efficiency.

  FIG. 12C is a schematic diagram when the engine operating point is higher than the α line. When the operating point corresponding to the required driving force is higher than the α line, the engine torque is reduced on the condition that the battery SOC has a margin, and the shortage is compensated by the power running of the motor generator 20. As a result, the required driving force can be achieved while improving the fuel efficiency.

  Next, the point that the WSC travel mode area is changed according to the estimated gradient will be described. FIG. 14 is an engine speed map when the vehicle speed is increased in a predetermined state. When the accelerator pedal opening is larger than APO1 on a flat road, the WSC travel mode region is executed up to a vehicle speed region higher than the lower limit vehicle speed VSP1. At this time, as the vehicle speed increases, the target engine speed gradually increases as shown in the map of FIG. Then, when the vehicle speed corresponding to VSP1 'is reached, the slip state of the second clutch 25 is canceled and a transition to the HEV travel mode is made.

  If an attempt is made to maintain the same vehicle speed increase state as described above on a gradient road where the estimated gradient is larger than the predetermined gradient (g1 or g2), the accelerator opening is increased accordingly. At this time, the transmission torque capacity TCL2 of the second clutch 25 is larger than that on a flat road. In this state, if the WSC travel mode area is enlarged as shown in the map shown in FIG. 13, the second clutch 25 will continue to slip with a strong engagement force, and the amount of heat generated may be excessive. is there. Therefore, in the MWSC compatible mode map shown in FIG. 10 that is selected when the estimated slope is large, the WSC travel mode area is not unnecessarily widened, but the area corresponding to the vehicle speed VSP1. Thereby, excessive heat generation in the WSC traveling mode can be avoided.

Next, the MWSC travel mode will be described.
When the estimated gradient is larger than the predetermined gradient (g1 or g2), for example, if the vehicle is to be maintained in a stopped state or a slow start state without operating the brake pedal, a large driving force is required as compared with a flat road. . This is because it is necessary to face the load load of the host vehicle.

  On the other hand, from the viewpoint of avoiding heat generation due to the slip of the second clutch 25, it is also conceivable to select the EV traveling mode when the SOC of the battery 30 has a margin. At this time, when the vehicle travels from the EV travel mode region to the WSC travel mode region, it is necessary to start the engine, and the motor generator 20 outputs the drive torque while securing the engine start torque, so the drive torque upper limit value is unnecessary. It is narrowed to.

  In the EV travel mode, when only torque is output to the motor generator 20 and the rotation of the motor generator 20 is stopped or rotated at a very low speed, a lock current flows through the switching element of the inverter (a phenomenon in which the current continues to flow through one element). , There is a risk of lowering durability.

  Furthermore, in a region lower than the lower limit vehicle speed VSP1 corresponding to the idle speed of the engine 10 at the first speed (region of VSP2 or less), the engine 10 itself cannot be reduced below the idle speed. At this time, if the WSC travel mode is selected, the slip amount of the second clutch 20 increases, which may affect the durability of the second clutch 20.

  In particular, since a large driving force is required on a slope road compared to a flat road, the transmission torque capacity required for the second clutch 20 is increased, and a high torque and high slip amount state is continued. Tends to cause a decrease in durability of the second clutch 20. In addition, since the vehicle speed rises slowly, it takes time until the transition to the HEV travel mode, and there is a risk of further generating heat.

  Therefore, in the present embodiment, while the engine 10 is operating, the first clutch 15 is released, and the transmission torque capacity of the second clutch 25 is controlled to the driver's required driving force, while the rotational speed of the motor generator 20 is The MWSC traveling mode is employed in which feedback control is performed to a target rotational speed that is higher by a predetermined rotational speed than the output rotational speed of the second clutch 25.

  In other words, the second clutch 25 is slip-controlled while the rotational state of the motor generator 20 is set to a rotational speed lower than the idle rotational speed of the engine. At the same time, the engine 10 switches to feedback control in which the idling speed is the target speed. In the WSC traveling mode, the engine speed is maintained by the rotational speed feedback control of the motor generator 20. On the other hand, in the MWSC travel mode, the first clutch 15 is released, so that when the first clutch 15 is released, the motor generator 20 cannot control the engine speed to the idle speed. Therefore, in the MWSC travel mode, the engine speed feedback control is performed by the engine 10 itself.

Next, clutch protection control in this embodiment will be described.
In the WSC travel mode or the MWSC travel mode, when the driver adjusts the accelerator pedal on the uphill road and the stall stop state in which the hybrid vehicle 1 is maintained in the stopped state continues, the slip amount of the second clutch 25 is excessive. The state continues and the second clutch 25 may overheat.

  Therefore, in the present embodiment, when such a stall stop state is detected, when the temperature of the second clutch 25 detected by the temperature sensor 64 is equal to or higher than a predetermined temperature indicating overheating, the first clutch 15 and The second clutch 25 is completely engaged, the engine 10 is stalled, and protection control for protecting the second clutch 25 is performed. And in order to implement | achieve such clutch protection control, the integrated control unit 60 is provided with the stall stop determination part 410, the clutch protection control part 420, the engine starting prohibition part 430, and the protection control cancellation | release part 440.

  The stall stop determination unit 410 is based on the road surface gradient estimated by the road surface gradient estimation unit 210 described above, the accelerator opening APO detected by the accelerator opening sensor 91, and the vehicle speed VSP detected by the vehicle speed sensor 92. It is determined whether the hybrid vehicle 1 is in a stall stop state. In this embodiment, when the driver is stepping on the accelerator on the uphill road and the vehicle speed VSP is substantially zero, it is determined that the vehicle is stalled, and at other times, the vehicle is not stalled. Is determined.

  The clutch protection control unit 420 determines that the temperature of the second clutch 25 detected by the temperature sensor 64 is equal to or higher than a predetermined temperature (predetermined temperature indicating overheating) when the stall stop determination unit 410 determines that the vehicle is stalled. It is determined whether or not there is, and when the temperature of the second clutch 25 is equal to or higher than a predetermined temperature, a command for completely engaging the first clutch 15 and the second clutch 25 is output. At this time, the second clutch transmission torque capacity TCL2 of the second clutch 25 is gradually increased up to the upper limit torque capacity at a predetermined rate of change in order to prevent a sudden start associated with an increase in the driving force of the hybrid vehicle 1. Let

  Furthermore, the clutch protection control unit 420 controls the rotational speed of the motor generator 20 according to the target rotational speed and the torque control of the engine 10 according to the target engine torque during clutch protection control.

  The target motor rotation speed of the motor generator 20 at the time of this protection control is set to a rotation speed at which a descending gradient of the motor rotation speed is determined so that the motor rotation speed becomes a predetermined rotation speed after the target time, and this falling gradient is obtained. Is done. Here, the target time may be appropriately set according to the distance and time to advance the hybrid vehicle 1 by the protection control. Further, the predetermined rotational speed is higher by an offset rotational speed than the upper limit value of the low-rotation resonance band of engine 10 (the rotational speed region in which engine 10 and the vehicle floor resonate and the sound vibration performance of hybrid vehicle 1 deteriorates). Can be a number.

  When the motor speed of motor generator 20 reaches a predetermined speed, the target motor speed is set to zero until the clutch protection control is released.

  Further, the target engine torque of the engine 10 at the time of the protection control is such that the total of the engine torque and the motor torque is equal to or less than the second clutch transmission torque capacity TCL2 until the engine speed reaches the predetermined speed. Set to torque. When the engine speed reaches the predetermined speed, the target engine speed is set to zero and the fuel cut of the engine 10 is performed until the engine 10 is stalled and the clutch protection control is released. .

  The engine start prohibition unit 430 determines whether or not the drive wheels 54 of the hybrid vehicle 1 are locked during the clutch protection control. If the drive wheels 54 of the hybrid vehicle 1 are locked, the engine 10 Is performed. When the drive wheels 54 of the hybrid vehicle 1 are not locked, control for prohibiting the start of the engine 10 is performed. In the present embodiment, whether or not the drive wheel 54 is locked is determined based on whether or not the shift range is set to the parking range (P range) by the shift lever operated by the driver. The shift range information can be acquired by the inhibitor switch 94. By determining whether or not the driving wheel 54 is locked based on whether or not the ft range is set to the P range, it is determined whether or not the driving wheel 54 is locked by a relatively simple mechanism. Can be done. Alternatively, a method of determining that the drive wheel 54 is locked when the brake is stepped on by the driver may be employed. However, when such a method is employed, voice or It is desirable to make an announcement via the display.

  The engine start prohibiting unit 430 issues a warning for prompting the driver to perform an operation for locking the drive wheels 54 when performing control for prohibiting the start of the engine 10. As a warning to the driver, for example, voice guidance such as “shift range to P range”, a display method, or the like can be given.

  The protection control release unit 440 determines whether or not the state where the drive wheels 54 of the hybrid vehicle 1 are locked and the state where the engine 10 is stopped continue for a predetermined time or longer during the clutch protection control. When these states continue for a predetermined time, control for releasing the clutch protection control is performed. The predetermined time is not particularly limited. For example, the predetermined time may be a time at which it can be determined that the temperature of the second clutch 25 is sufficiently lower than the predetermined temperature described above. it can.

  Next, switching processing for switching from the clutch protection control mode to the normal control mode in the present embodiment will be described with reference to the flowchart shown in FIG. Here, the normal control mode refers to the engine 10, the motor generator 20, based on the vehicle speed VSP, the accelerator opening APO, the SOC of the battery 30, and the like according to the above-described method in the normal WSC travel mode or MWSC travel mode. In this mode, the first clutch 15 and the second clutch 25 are controlled.

  In the processing described below, the stall stop state is detected by the stall stop determination unit 410 of the integrated control unit 60 in the WSC drive mode or the MWSC drive mode in the normal control mode, and the clutch protection control of the integrated control unit 60 is performed. This process is performed when the clutch protection control mode is set by the unit 420, and is repeatedly executed at a predetermined control cycle (for example, 10 ms).

  First, in step S1, the engine start prohibiting unit 430 of the integrated control unit 60 determines whether or not the drive wheels 54 of the hybrid vehicle 1 are locked. In the present embodiment, whether or not the drive wheel 54 is locked is determined based on whether or not the shift range is set to the parking range (P range) by the shift lever operated by the driver. If it is determined that the drive wheel 54 is locked, the process proceeds to step S2. On the other hand, if it is determined that the drive wheel 54 is not locked, the process proceeds to step S5, where the engine start prohibiting unit 430 performs a process for prohibiting the start of the engine 10, and then the process proceeds to step S6. On the other hand, a warning for prompting an operation for locking the drive wheel 54 is performed, and the protection control mode is continued (step S7), and the process returns to step S1.

  On the other hand, if it is determined in step S1 that the drive wheels 54 are locked, the process proceeds to step S2, and the engine start prohibiting unit 430 performs control to permit the engine 10 to start, and the process proceeds to step S3. .

  In step S3, the protection control cancellation unit 440 determines whether or not the state where the drive wheels 54 of the hybrid vehicle 1 are locked and the state where the engine 10 is stopped have continued for a predetermined time or more. . If the duration of these states is less than the predetermined time, the process proceeds to step S7, and the process returns to step S1 while the protection control mode is continued. On the other hand, when the state in which the drive wheels 54 of the hybrid vehicle 1 are locked and the state in which the engine 10 is stopped continues for a predetermined time or longer, the process proceeds to step S4 and the process of switching to the normal control mode is performed. Done.

  FIG. 16 is a time chart showing clutch protection control according to the present embodiment. FIG. 16 shows the time when the switching from the normal control mode to the clutch protection control mode is performed at time t1, and then the switching from the clutch protection control mode to the normal control mode is performed at time t7. A chart is shown.

  At the time t1, the stall stop determination unit 410 of the integrated control unit 60 determines that the hybrid vehicle 1 is in a stall stop state, and the clutch protection control unit 420 of the integrated control unit 60 starts the clutch protection control from the normal control mode. Processing for shifting to the mode is performed.

  From t1 to t2, since the delay time has not elapsed since time t1, normal control in the WSC travel mode is continued. Here, the delay time is set longer as the accelerator opening APO is higher. This is because the time from the determination of overheating of the second clutch 25 to the engine stall is constant regardless of the accelerator opening APO.

  At the time t2, since the delay time has elapsed from the time t1, the engine start prohibiting unit 430 of the integrated control unit 60 performs control for prohibiting the start of the engine 10.

  Then, in the interval from t2 to t3, the second clutch transmission torque capacity TCL2 of the second clutch 25 is determined from the value corresponding to the accelerator opening APO, and the upper limit torque of the second clutch 25 at which the second clutch 25 is in the fully engaged state. A process of gradually increasing the capacity up to the capacity at a predetermined rising gradient is performed. At the same time, the motor rotational speed of the motor generator 20 becomes a predetermined rotational speed (a rotational speed higher by an offset rotational speed than the upper limit value (400 rpm) of the low rotational resonance band of the engine 10) after elapse of a predetermined time from the time t2. Thus, a process for performing the rotational speed control for gradually decreasing the target rotational speed is performed.

  Simultaneously with the rotational speed control of the motor generator 20, the torque control is performed so that the target engine torque of the engine 10 is the engine torque such that the sum of the engine torque and the motor torque is equal to or less than the clutch torque. In the section of t3, the engine speed decreases due to engine torque limitation, and the motor torque is limited by the target driving force, so that overheating of the second clutch 25 can be suppressed. Note that, from t2 to t3, the engine speed is gradually reduced by such control, the engine 10 is stalled at the time t3, and the engine speed is zero at the time t4. Further, the target driving force gradually increases from t2 to t3, and is zero at the time t3. At time t3, when the engine 10 is stalled, if the shift range is other than the P range, a warning is issued to prompt the driver to change the shift range to the P range. . In addition, from t2 to t3, by gradually increasing the target driving force, the acceleration of the hybrid vehicle 1 increases and the hybrid vehicle 1 moves forward slightly, but the rising gradient of the target driving force is set smoothly. Therefore, sudden start can be prevented.

  In addition, from t3 to t4, the acceleration decreases due to the engine 10 stalling, so that the hybrid vehicle 1 slightly moves backward, but the drive wheels 54 are directly connected to the stopped engine 10, so that the engine 10 Friction (engine braking) can be used to suppress vehicle slipping. Further, since the hybrid vehicle 1 is moved forward by a predetermined distance from t2 to t3, the vehicle does not move backward to a position lower than the position at the start of protection control.

  As described above, in the interval from t2 to t3, the second clutch transmission torque capacity TCL2 is increased to the upper limit torque capacity and the second clutch 25 is completely engaged. Therefore, overheating of the second clutch 25 can be suppressed and protection can be achieved. it can.

  Moreover, in the section from t2 to t4, the vehicle is moved forward by a predetermined distance and then moved backward by engine stall, so that the driver can step on the brake pedal from the accelerator pedal to the driver by acceleration change before and after engine stall and engine stop sound. Replacement can be urged, and the sliding down of the hybrid vehicle 1 can be suppressed.

  Next, at time t5, when the driver operates the shift range to be the P range and the drive wheels 54 are locked, the engine start prohibiting unit 430 of the integrated control unit 60 allows the engine 10 to be started. Is done. In addition, the warning for prompting the driver to change the shift range to the P range is turned off.

  Next, after the driver performs an operation to increase the accelerator opening at the time t6, the shift range is set to the P range at the time t7, and the drive wheels 54 of the hybrid vehicle 1 are locked, and the engine 10 Is stopped for a predetermined time or longer, and control for shifting from the clutch protection control mode to the normal control mode is performed. As a result of shifting to the normal control mode, the target driving force increases, and accordingly, the engine 10 is started and the engine speed increases.

  According to the present embodiment, during the clutch protection control mode, an operation for setting the shift range to the P range is performed, and the start of the engine 10 is prohibited until the drive wheel 54 is locked, and the shift range is set to the P range. When the drive wheel 54 is locked, the engine 10 is allowed to start. Therefore, according to the present embodiment, the clutch protection control mode can be appropriately released.

  In particular, unlike the present embodiment, when the engine 10 is started in a state where the drive wheels 54 are not locked, the driver determines that the hybrid vehicle 1 is ready to travel. In such a case, the clutch protection control mode state time is short, the temperature of the clutch 25 is not sufficiently lowered, and the clutch protection control mode is entered again. . On the other hand, according to the present embodiment, during the clutch protection control mode, the operation of setting the shift range to the P range is performed, and the start of the engine 10 is prohibited until the drive wheels 54 are locked. Such a problem is effectively solved. In particular, it is possible to effectively prevent the driver from starting the hybrid vehicle 1 immediately by setting the shift range to the P range once.

  In addition, according to the present embodiment, when the shift range is set to the P range and the drive wheels 54 are locked, the start of the engine 10 is permitted, so that a change in vehicle behavior due to the start of the engine is prevented. As a result, the hybrid vehicle 1 can be prevented from sliding down when starting the engine on the uphill road.

  In addition, according to the present embodiment, when the shift range is set to the P range and the drive wheel 54 of the hybrid vehicle 1 is locked for a predetermined time or longer, the normal control is performed from the clutch protection control mode. The clutch protection control mode can be canceled more appropriately by performing the control for shifting to the mode and thereby permitting the return of the driving force.

  In the above-described embodiment, the temperature sensor 64 is used as the temperature detection unit of the present invention, the stall stop determination unit 410 of the integrated control unit 60 is used as the stall stop state determination unit of the present invention, and the clutch protection control unit of the integrated control unit 60 is used. 420 and the protection control release unit 440 correspond to the clutch protection control unit of the present invention, and the engine start prohibiting unit 430 of the integrated control unit 60 corresponds to the start prohibiting unit of the present invention.

  As mentioned above, although embodiment of this invention was described, these embodiment was described in order to make an understanding of this invention easy, and was not described in order to limit this invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Hybrid vehicle 10 ... Engine 15 ... 1st clutch 20 ... Motor generator 25 ... 2nd clutch 30 ... Battery 35 ... Inverter 40 ... Automatic transmission 60 ... Integrated control unit 70 ... Engine control unit 80 ... Motor control unit 90 ... Transmission control unit

Claims (3)

An internal combustion engine, a motor generator, a first clutch that is interposed between the internal combustion engine and the motor generator, and connects and disconnects the internal combustion engine and the motor generator, and is interposed between the motor generator and a drive wheel. A hybrid vehicle control device that outputs a control signal to a hybrid vehicle including a second clutch that connects and disconnects the motor generator and the drive wheel,
Temperature detecting means for detecting the temperature of the second clutch;
On the uphill road, the stall stop state determination means for determining the stall stop state in which the driver adjusts the accelerator pedal and maintains the vehicle stop state;
Clutch protection control means for performing clutch protection control for engaging both the first clutch and the second clutch when the stalled stop state is determined and the temperature of the second clutch is equal to or higher than a predetermined temperature;
When clutch protection control is being performed by the clutch protection control means, it is determined whether or not the drive wheel is locked, and when it is determined that the drive wheel is not locked, the internal combustion engine And a start prohibiting means for prohibiting start of the vehicle. In the hybrid vehicle control device according to claim 1,
The start prohibiting means determines whether or not the driving wheel is locked based on shift range information. In the hybrid vehicle control device according to claim 1 or 2,
The control apparatus for a hybrid vehicle, wherein the clutch protection control means releases the clutch protection control when a predetermined time or more has elapsed after the drive wheels are locked.

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