JP7487474B2 - Assist control device - Google Patents

Description

The present invention relates to an assist control device.

Patent document 1 discloses a hybrid vehicle in which, when the clutch is in a half-clutch state, the electric motor is controlled to generate a starting assist torque equal to the difference between the driver-requested torque requested by the driver and the idling torque generated by the engine when idling.

In the hybrid vehicle disclosed in Patent Document 1, when the road is an uphill road with a predetermined gradient or more, the correction unit corrects the assist start torque, which is a threshold value for determining whether or not to assist the engine with the driving force of the electric motor, in accordance with the gradient so that the assist start torque is larger than the assist start torque on a flat road. Furthermore, when the road is an uphill road with a predetermined gradient or more, the correction unit corrects the assist full torque, which is the upper limit of the torque of the electric motor when assisting the engine with the driving force of the electric motor, in accordance with the gradient so that the assist full torque is smaller than the assist full torque on a flat road.

As a result, in the hybrid vehicle disclosed in Patent Document 1, when the gradient of an uphill road is steep, the assist start torque is intentionally increased and only the torque deficiency of the engine is compensated for by the electric motor, and basic power (torque) is generated by the engine, thereby preventing excessive discharge of the battery and shortening the period in which the clutch is in a half-clutch state.

International Publication No. 2012/053596

However, in the hybrid vehicle described in Patent Document 1, when the gradient of an uphill road is large, the assist torque acting on the clutch output shaft is small, so the clutch is engaged with a high load on the clutch output shaft, resulting in a large amount of heat generated by the clutch. To reduce this amount of heat generation, it is necessary to reduce the amount of change in torque transmitted from the clutch input shaft to the clutch output shaft and lengthen the period of the half-clutch state. In this case, the transition time required to transition the clutch from the half-clutch state to the engaged state becomes longer, impairing the vehicle's starting and acceleration capabilities on steep uphill roads.

In addition, in the hybrid vehicle described in Patent Document 1, there is a risk that the SOC will decrease due to the electric motor frequently assisting the engine on flat roads. If the SOC decreases, the torque that can be output by the electric motor is limited, and even if the engine is assisted on a steep uphill road, the desired assist torque cannot be output, which may result in a loss of starting and acceleration capabilities of the vehicle.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide an assist control device that can improve starting and acceleration performance on steep gradients while suppressing heat generation in the clutch.

In order to achieve the above-mentioned object, the present invention provides an assist control device for a vehicle equipped with an engine, a transmission that changes the rotation of the engine and transmits it to driving wheels, a clutch that disconnects or connects the power transmission path between the transmission and the engine, and a motor capable of transmitting power to the driving wheels, and includes a control unit that executes climbing assist control that outputs assist torque from the motor to the driving wheels when the execution conditions are met, with the execution conditions being that the road is an uphill road with a predetermined gradient or more, the clutch is in a disengaged state including a half-engaged state, and there is no request for a gear change, and the control unit has two conditions: that the clutch has transitioned from a disengaged state to an engaged state, and that the vehicle speed, which is the speed of the vehicle, has become a predetermined vehicle speed or higher, and is configured to stop the climbing assist control when at least one of these two conditions is met .

The present invention provides an assist control device that can improve starting and acceleration performance on steep gradients while suppressing heat generation in the clutch.

FIG. 1 is a block diagram of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a block diagram showing the functions of an HCU of a hybrid vehicle according to one embodiment of the present invention. FIG. 3 is a flowchart showing the flow of a hill climbing assist determination process executed by the HCU of the hybrid vehicle according to one embodiment of the present invention. FIG. 4 is a flowchart showing a flow of the acceleration assist determination process executed by the HCU of the hybrid vehicle according to one embodiment of the present invention. FIG. 5 is a time chart showing an example of a case where the hill climbing assist control is executed in the hybrid vehicle according to the embodiment of the present invention. FIG. 6 is a flowchart showing the flow of a shift assist determination process executed by the HCU of the hybrid vehicle according to one embodiment of the present invention.

The assist control device according to one embodiment of the present invention is an assist control device for a vehicle equipped with an engine, a transmission that changes the speed of the engine rotation and transmits it to the drive wheels, a clutch that disconnects or connects the power transmission path between the transmission and the engine, and a motor that can transmit power to the drive wheels. The assist control device is equipped with a control unit that executes hill climbing assist control that outputs assist torque from the motor to the drive wheels when the execution conditions are met, with the road being uphill with a predetermined gradient or more, the clutch being in a disengaged state including a half-engaged state, and there being no request for a gear change, and the control unit stops the hill climbing assist control when the clutch transitions from a disengaged state to an engaged state.

As a result, the assist control device according to one embodiment of the present invention can improve starting and acceleration performance on steep gradients while suppressing heat generation in the clutch.

Below, an assist control device according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a hybrid vehicle 1 as a vehicle includes an engine 2, a transmission 3 as a gearbox, a motor generator 4 as a motor, drive wheels 5, an HCU (Hybrid Control Unit) 10 that controls the hybrid vehicle 1 overall, an ECM (Engine Control Module) 11 that controls the engine 2, a TCM (Transmission Control Module) 12 that controls the transmission 3, an ISGCM (Integrated Starter Generator Control Module) 13, an INVCM (Inverter Control Module) 14, a low-voltage BMS (Battery Management System) 15, and a high-voltage BMS 16. The engine 2 and the motor generator 4 constitute a drive source that transmits power to a drive shaft 23 as a drive shaft. The HCU 10 in this embodiment constitutes a control unit.

In this embodiment, the engine 2 is an internal combustion engine. The engine 2 has multiple cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, which are an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

An ISG (Integrated Starter Generator) 20 and a starter 21 are connected to the engine 2. The ISG 20 is connected to the crankshaft 18 of the engine 2 via a power transmission member such as a belt or chain. The ISG 20 functions as an electric motor that rotates when supplied with electric power to drive the engine 2, and as a generator that converts the rotational force input from the crankshaft 18 into electric power.

In this embodiment, the ISG 20 functions as an electric motor under the control of the ISGCM 13, restarting the engine 2 from a stopped state caused by the idling stop function. The ISG 20 can also assist the running of the hybrid vehicle 1 by functioning as an electric motor.

The starter 21 is configured to include a motor and a pinion gear (not shown). The starter 21 rotates the motor to rotate the crankshaft 18, thereby providing the engine 2 with a rotational force at the time of starting. In this way, the engine 2 is started by the starter 21, and is restarted by the ISG 20 from a stopped state caused by the idling stop function.

The transmission 3 changes the speed of the rotation output from the engine 2 and transmits it to the drive wheels 5 via the drive shaft 23 to drive the drive wheels 5. The transmission 3 includes a constant mesh type speed change mechanism 25 consisting of a parallel shaft gear mechanism, a clutch 26 consisting of a normally closed type dry clutch, a differential mechanism 27 as a reducer, and actuators 51 and 52.

The clutch 26 is provided between the transmission mechanism 25 and the engine 2, and is switched between engaged and disengaged to disconnect or connect the power transmission path between the drive wheels 5 and the engine 2.

The transmission 3 is configured as a so-called AMT (Automated Manual Transmission) and is configured to be able to establish multiple gear stages, including multiple forward gear stages and multiple reverse gear stages. In the transmission 3, the gear stages in the speed change mechanism 25 are changed by an actuator 52 controlled by the TCM 12, and the clutch 26 is engaged and disengaged by an actuator 51. The differential mechanism 27 transmits the power output by the speed change mechanism 25 to the drive shaft 23. The power transmitted to the drive shaft 23 is transmitted to the drive wheels 5.

The motor generator 4 is connected to the differential mechanism 27 via a power transmission member 28 such as a chain. The motor generator 4 is connected to the drive shaft 23 via the differential mechanism 27. The motor generator 4 functions as an electric motor.

In this way, the hybrid vehicle 1 forms a parallel hybrid system that can use the power of both the engine 2 and the motor generator 4 to drive the vehicle, and is designed to run using the power output by at least one of the engine 2 and the motor generator 4.

The driving modes of the hybrid vehicle 1 include at least an HEV driving mode in which the driving force of the engine 2 and the motor generator 4 is transmitted to the drive shaft 23 to drive the hybrid vehicle 1, and an EV driving mode in which fuel injection to the engine 2 is stopped, the engine 2 is stopped, and the driving force of only the motor generator 4 is transmitted to the drive shaft 23 to drive the hybrid vehicle 1 in EV driving.

The motor generator 4 also functions as a generator that generates electricity using the rotation of the drive wheels 5, and generates electricity as the hybrid vehicle 1 runs. Note that the motor generator 4 only needs to be connected to any point in the power transmission path from the engine 2 to the drive wheels 5 so that it can transmit power, and does not necessarily have to be connected to the differential mechanism 27.

The hybrid vehicle 1 includes a first power storage device 30, a low-voltage power pack 32 including a second power storage device 31, a high-voltage power pack 34 including a third power storage device 33 as a battery, a high-voltage cable 35, and a low-voltage cable 36.

The first storage device 30, the second storage device 31, and the third storage device 33 are composed of rechargeable secondary batteries. The first storage device 30 is composed of a lead battery. The second storage device 31 is a storage device with higher output and higher energy density than the first storage device 30.

The second storage device 31 can be charged in a shorter time than the first storage device 30. In this embodiment, the second storage device 31 is a lithium ion battery. The second storage device 31 may also be a nickel-metal hydride battery.

The first storage battery 30 and the second storage battery 31 are low-voltage batteries in which the number of cells is set to generate an output voltage of approximately 12 V. The third storage battery 33 is, for example, a lithium-ion battery.

The third storage device 33 is a high-voltage battery in which the number of cells is set so as to generate a higher voltage than the first storage device 30 and the second storage device 31, and generates an output voltage of, for example, 100 V. The state of the third storage device 33, such as its remaining capacity (hereinafter referred to as "battery remaining capacity"), is managed by the high-voltage BMS 16.

The hybrid vehicle 1 is provided with a general load 37 and a protected load 38 as electrical loads. The general load 37 and the protected load 38 are electrical loads other than the starter 21 and the ISG 20.

The protected load 38 is an electrical load that requires a constant stable power supply. The protected load 38 includes, for example, lamps on an instrument panel (not shown).

General loads 37 are electrical loads that do not require a stable power supply compared to protected loads 38 and are used temporarily. General loads 37 include, for example, windshield wipers (not shown).

The low-voltage power pack 32 has switches 40, 41, and a low-voltage BMS 15 in addition to the second storage device 31. The first storage device 30 and the second storage device 31 are connected via a low-voltage cable 36 so as to be able to supply power to the starter 21, the ISG 20, and a general load 37 and a protected load 38 as electrical loads. The first storage device 30 and the second storage device 31 are electrically connected in parallel to the protected load 38.

The switch 40 is provided in the low-voltage cable 36 between the second storage device 31 and the protected load 38. The switch 41 is provided in the low-voltage cable 36 between the first storage device 30 and the protected load 38.

The low-voltage BMS 15 controls the opening and closing of switches 40 and 41 to control the charging and discharging of the second storage device 31 and the supply of power to the protected load 38. When the engine 2 is stopped due to an idling stop, the low-voltage BMS 15 closes switch 40 and opens switch 41 to supply power from the high-output, high-energy-density second storage device 31 to the protected load 38.

When the engine 2 is started by the starter 21, and when the engine 2 that has been stopped by idling stop control is restarted by the ISG 20, the low-voltage BMS 15 closes the switch 40 and opens the switch 41 to supply power from the first storage device 30 to the starter 21 or the ISG 20. When the switch 40 is closed and the switch 41 is open, power is also supplied from the first storage device 30 to the general load 37.

In this way, the first storage device 30 is configured to supply power at least to the starter 21 and the ISG 20, which serve as starting devices for starting the engine 2. The second storage device 31 is configured to supply power at least to the general load 37 and the protected load 38.

The second storage device 31 is connected so that it can supply power to both the general load 37 and the protected load 38, but the switches 40 and 41 are controlled by the low-voltage BMS 15 so that power is supplied preferentially to the protected load 38, which always requires a stable power supply.

The low-voltage BMS 15 may take into consideration the charge state (remaining charge) of the first storage device 30 and the second storage device 31, as well as the operation requests of the general load 37 and the protected load 38, and may control the switches 40, 41 differently from the example described above, prioritizing stable operation of the protected load 38.

The high-voltage power pack 34 has an inverter 45, an INVCM 14, and a high-voltage BMS 16 in addition to the third power storage device 33. The high-voltage power pack 34 is connected to the motor generator 4 via a high-voltage cable 35 so as to be able to supply power to the motor generator 4.

The inverter 45, under the control of the INVCM 14, converts between the AC power applied to the high-voltage cable 35 and the DC power applied to the third power storage device 33. For example, when the INVCM 14 powers the motor generator 4, it converts the DC power discharged by the third power storage device 33 into AC power using the inverter 45 and supplies it to the motor generator 4.

When the motor generator 4 is in a regenerative mode, the INVCM 14 converts the AC power generated by the motor generator 4 into DC power using the inverter 45 and charges the third power storage device 33.

The HCU10, ECM11, TCM12, ISGCM13, INVCM14, low-voltage BMS15 and high-voltage BMS16 are each composed of a computer unit equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports and output ports.

The ROM of these computer units stores various constants, maps, etc., as well as programs for causing the computer units to function as the HCU 10, ECM 11, TCM 12, ISGCM 13, INVCM 14, low-voltage BMS 15, and high-voltage BMS 16.

In other words, the CPU executes the programs stored in the ROM using the RAM as a working area, and these computer units function as the HCU 10, ECM 11, TCM 12, ISGCM 13, INVCM 14, low-voltage BMS 15, and high-voltage BMS 16 in this embodiment, respectively.

In this embodiment, the ECM 11 is configured to execute idling stop control. In this idling stop control, the ECM 11 stops the engine 2 when a predetermined stop condition is met, and drives the ISG 20 via the ISGCM 13 to restart the engine 2 when a predetermined restart condition is met. This prevents unnecessary idling of the engine 2, improving the fuel efficiency of the hybrid vehicle 1.

The hybrid vehicle 1 is provided with CAN communication lines 48, 49 for forming an in-vehicle LAN (Local Area Network) that conforms to standards such as CAN (Controller Area Network).

The HCU 10 is connected to the INVCM 14 and the high-voltage BMS 16 via a CAN communication line 48. The HCU 10, the INVCM 14, and the high-voltage BMS 16 transmit and receive signals such as control signals to and from each other via the CAN communication line 48.

The HCU 10 is connected to the ECM 11, the TCM 12, the ISGCM 13, and the low-voltage BMS 15 via a CAN communication line 49. The HCU 10, the ECM 11, the TCM 12, the ISGCM 13, and the low-voltage BMS 15 transmit and receive signals such as control signals to and from each other via the CAN communication line 49.

Connected to the HCU 10 are a wheel speed sensor 10a that detects the wheel speed of each wheel including the drive wheels 5, an accelerator opening sensor 10b that detects the amount of operation of the accelerator pedal 8 as the accelerator opening, a clutch stroke sensor 10c that detects the degree of engagement of the clutch 26, a crank angle sensor 10d, and an acceleration sensor 10e. The HCU 10 calculates the engine speed, which is the rotation speed of the engine 2, based on the detection information from the crank angle sensor 10d.

The wheel speed sensor 10a outputs a pulse signal that generates a pulse every time the wheel rotates a predetermined angle as a vehicle speed pulse. The HCU 10 calculates the vehicle speed of the hybrid vehicle 1 based on this vehicle speed pulse.

The acceleration sensor 10e detects the acceleration of the hybrid vehicle 1 and outputs the detection result to the HCU 10. In this embodiment, the acceleration sensor 10e detects the acceleration of the hybrid vehicle 1, but the HCU 10 may be configured to calculate the acceleration of the hybrid vehicle 1 based on the above-mentioned vehicle speed and temporal changes in the rotation speed of the motor generator 4.

The acceleration sensor 10e also detects the gradient of the road surface on which the hybrid vehicle 1 is traveling or stopped based on the inclination of the hybrid vehicle 1 in the longitudinal direction, and outputs the detection result to the HCU 10. In this embodiment, the gradient of the road surface is detected by the acceleration sensor 10e, but the HCU 10 may detect the gradient of the road surface based on information obtained from the map information acquisition unit 10f and the position information acquisition unit 10g, which will be described later.

As shown in FIG. 2, in addition to the above sensors, a map information acquisition unit 10f and a location information acquisition unit 10g are connected to the HCU 10.

The map information acquisition unit 10f is made up of a car navigation device, and is configured to acquire map information including uphill road information and transmit it to the HCU 10. The map information is stored in a storage medium of the car navigation device. The map information acquisition unit 10f is not limited to a car navigation device, and may be, for example, application software such as a map app installed on a mobile terminal such as a smartphone or tablet terminal.

The location information acquisition unit 10g is composed of a GPS receiver and is configured to measure the current location of the hybrid vehicle 1 using the Global Positioning System (GPS) and transmit the measured current location to the HCU 10.

The HCU 10 functions as a road surface gradient determination unit 101 that determines whether the road surface on which the hybrid vehicle 1 is traveling or stopped is an uphill road with a predetermined gradient (e.g., 20%) or more based on the detection results input from the acceleration sensor 10e.

The HCU 10 functions as a clutch state determination unit 102 that determines whether the clutch 26 is in a disengaged state, including a half-engaged state, or in an engaged state, which is a fully engaged state, based on the detection results input from the clutch stroke sensor 10c. The disengaged state of the clutch 26 includes a disengaged state in which no power is transmitted between the frictional engagement element 26a on the engine side of the clutch 26 and the frictional engagement element 26b on the transmission side.

The semi-engaged state refers to a state in which the frictional engagement element 26a on the engine side of the clutch 26 and the frictional engagement element 26b on the transmission side are engaged and rotate relative to each other with slippage occurring between them. The fully engaged state refers to an engaged state in which the frictional engagement element 26a on the engine side of the clutch 26 and the frictional engagement element 26b on the transmission side rotate together without slippage occurring.

The HCU 10 has a function as a shift request determination unit 103 that determines whether or not to perform a shift in the transmission 3 by referring to a shift map based on the accelerator opening and vehicle speed, and determines whether or not there is a request for a shift (hereinafter referred to as a "shift request") based on the result of this determination. The shift map is a relationship between the accelerator opening, vehicle speed, and shift timing that has been experimentally obtained in advance, and is stored in the ROM of the HCU 10.

The HCU 10 functions as an acceleration request determination unit 104 that determines whether an acceleration request value indicating the degree of acceleration request for the hybrid vehicle 1 is equal to or greater than a predetermined value. The aforementioned predetermined values include a "first predetermined value" used to determine the execution conditions for the hill climbing assist control described below, and a "second predetermined value" used to determine the execution conditions for the acceleration assist control described below. In this embodiment, the first predetermined value is set to a value greater than the second predetermined value.

The accelerator opening can be used as the acceleration request value, and in this case, the first predetermined value is set to, for example, 75% of the accelerator opening. In addition, the depression speed of the accelerator pedal 8, i.e., the amount of change in the accelerator opening per unit time, can also be used as the acceleration request value.

The acceleration request for the hybrid vehicle 1 described above may include an acceleration request due to the driver depressing the accelerator pedal 8, as well as an acceleration request that is requested in response to the difference between a set vehicle speed and an actual vehicle speed when the vehicle is traveling regardless of the driver's accelerator operation, such as in cruise control or automatic driving.

The HCU 10 has a function as a battery status determination unit 105 that acquires the remaining battery capacity of the third storage device 33 from the high-voltage BMS 16, and determines whether the remaining battery capacity of the third storage device 33 is equal to or greater than a first threshold, and determines whether the remaining battery capacity is equal to or greater than a second threshold.

The first threshold is the lower limit of the remaining battery charge at which the hill climbing assist control described below can be executed, and is experimentally determined in advance and stored in the ROM of the HCU 10. The second threshold is a value greater than the first threshold, and is the lower limit of the remaining battery charge at which the acceleration assist control described below can be executed, and is experimentally determined in advance and stored in the ROM of the HCU 10.

The HCU 10 functions as an uphill road information acquisition unit 106 that acquires uphill road information on the driving route from the current position to the destination based on input information from the map information acquisition unit 10f and the position information acquisition unit 10g. The destination is the destination set in the car navigation device. When a map application is used as the map information acquisition unit 10f, the destination is the destination set in the map application. The uphill road information includes at least information such as the presence or absence of an uphill road on the driving route to the destination, the gradient of the uphill road, the distance to the uphill road, and the length of the uphill road.

When the HCU 10 determines, based on the uphill road information acquired as described above, that an uphill road with a gradient of at least a predetermined level exists on the driving route from the current location to the destination, it ensures that the third power storage device 33 has a remaining battery capacity equal to or greater than the first threshold value by the time the vehicle reaches the uphill road from the current location.

For example, the HCU 10 can ensure or maintain the remaining battery charge at or above the first threshold by generating electricity using the motor generator 4 or the ISG 20 to increase the remaining battery charge, or by limiting assist control other than the climbing assist control, such as acceleration assist control. In addition, the HCU 10 may generate electricity using the ISG 20 simultaneously with assist control other than the climbing assist control, or may generate electricity using the ISG 20 by driving the engine 2.

When the HCU 10 determines based on the uphill road information that there is no uphill road with a gradient of a predetermined gradient or more on the driving route from the current position to the destination, the HCU 10 may prohibit each of the above processes for ensuring that the remaining battery capacity is equal to or greater than the first threshold.

The HCU 10 has a timer 107. The timer 107 measures various times. For example, the timer 107 measures the elapsed time from the start of execution of the hill climbing assist control, which will be described later.

The HCU 10 executes hill climbing assist control that outputs assist torque from the motor generator 4 to the drive wheels 5 when the execution conditions are met, with the road surface on which the hybrid vehicle 1 is traveling or stopped being an uphill road with a predetermined gradient or more, the clutch 26 being in a disengaged state, and there being no request for a gear shift. Hereinafter, the assist torque in the hill climbing assist control will be referred to as "hill climbing assist torque."

The conditions for executing the hill climbing assist control include the acceleration requirement value for the hybrid vehicle 1 being equal to or greater than a first predetermined value. Note that the acceleration requirement value for the hybrid vehicle 1 being equal to or greater than the first predetermined value does not have to be one of the conditions for executing the hill climbing assist control.

The conditions for executing the hill climbing assist control also include the remaining battery capacity of the third power storage device 33 being equal to or greater than the first threshold. Note that the remaining battery capacity of the third power storage device 33 being equal to or greater than the first threshold does not necessarily have to be one of the conditions for executing the hill climbing assist control.

In addition, one of the conditions for executing the hill-climbing assist control may be that the gear stage or gear ratio is less than a predetermined value. As a result, when the gear stage or gear ratio is large, the gear stage or gear ratio is lowered to increase the output torque before the execution of the hill-climbing assist control is started, so that the assist amount and assist frequency of the hill-climbing assist torque can be suppressed, thereby suppressing the power consumption of the third power storage device 33.

The HCU 10 stops the hill climbing assist control when any of the following first to fourth stop conditions is met.

The first stop condition is that the clutch 26 has transitioned from a non-engaged state to an engaged state. The second stop condition is that the vehicle speed is equal to or greater than a predetermined vehicle speed. The third stop condition is that the remaining battery capacity of the third power storage device 33 is less than a first threshold value. The fourth stop condition is that a predetermined time has elapsed since the start of execution of the hill climbing assist control.

The HCU 10 can execute acceleration assist control in which an assist torque is output from the motor generator 4 to the drive wheels 5 in response to an acceleration request for the hybrid vehicle 1. That is, the HCU 10 executes acceleration assist control on the condition that the acceleration request value for the hybrid vehicle 1 is equal to or greater than a second predetermined value. Hereinafter, the assist torque in the acceleration assist control is referred to as "acceleration assist torque."

The acceleration assist control is executed on the condition that the remaining battery capacity of the third storage device 33 is equal to or greater than a second threshold value that is greater than the first threshold value. Note that the remaining battery capacity of the third storage device 33 being equal to or greater than the second threshold value does not have to be one of the conditions for executing the acceleration assist control.

Next, the flow of the hill climbing assist determination process executed by the HCU 10 will be described with reference to FIG. 3. The hill climbing assist determination process shown in FIG. 3 is repeatedly executed at a predetermined time interval.

As shown in FIG. 3, the HCU 10 determines whether or not there is a gear shift request (step S1). If the HCU 10 determines in step S1 that there is a gear shift request, the HCU 10 ends this hill climbing assist determination process. If the HCU 10 determines in step S1 that there is no gear shift request, the HCU 10 determines whether or not the road surface on which the hybrid vehicle 1 is traveling or stopped is an uphill road with a predetermined gradient or more (step S2).

If the HCU 10 determines in step S2 that the road surface is not an uphill road with a predetermined gradient or more, it ends this hill climbing assistance determination process. If the HCU 10 determines in step S2 that the road surface is an uphill road with a predetermined gradient or more, it determines whether the acceleration requirement value for the hybrid vehicle 1 is equal to or greater than a first predetermined value (step S3).

In step S3, it is preferable for the HCU 10 to determine whether the acceleration request value has changed from a state where it was less than the first predetermined value to a state where it is equal to or greater than the first predetermined value. As a result, after the climb assist control is stopped, the climb assist control will not be executed unless the acceleration request value again becomes equal to or greater than the first predetermined value after it has become less than the first predetermined value. Therefore, even if the climb assist control is stopped when the acceleration request value is equal to or greater than the first predetermined value, for example, the climb assist control is prevented from being resumed immediately thereafter.

If the HCU 10 determines in step S3 that the acceleration requirement value is not equal to or greater than the first predetermined value, the HCU 10 ends this hill climbing assistance determination process. If the HCU 10 determines in step S3 that the acceleration requirement value is equal to or greater than the first predetermined value, the HCU 10 determines whether the clutch 26 is in a disengaged state, including a half-engaged state (step S4).

If the HCU 10 determines in step S4 that the clutch 26 is not disengaged, the HCU 10 ends this hill climbing assist determination process. If the HCU 10 determines in step S4 that the clutch 26 is disengaged, the HCU 10 determines whether the remaining battery capacity of the third storage device 33 is equal to or greater than the first threshold (step S5).

If the HCU 10 determines in step S5 that the remaining battery capacity of the third storage device 33 is not equal to or greater than the first threshold, the HCU 10 ends this hill climbing assist determination process. If the HCU 10 determines in step S5 that the remaining battery capacity of the third storage device 33 is equal to or greater than the first threshold, the HCU 10 executes hill climbing assist control (step S6).

When the hill climbing assist control is executed in step S6, a hill climbing assist torque is output from the motor generator 4 to the drive wheels 5. Therefore, while the hill climbing assist control is being executed, the torque required by the hybrid vehicle 1 is the sum of the engine torque output from the engine 2 and transmitted to the drive shaft 23 via the clutch 26 and the transmission 3 and the hill climbing assist torque (hereinafter referred to as "total torque"), which is transmitted to the drive wheels 5. The hill climbing assist torque is set to the torque required by the hybrid vehicle 1 minus the aforementioned engine torque.

The total torque is set to at least a torque that can ensure a driving force (hereinafter referred to as the "required driving force") that allows the hybrid vehicle 1 to start or run at a predetermined acceleration on an uphill road with a predetermined gradient.

Next, the HCU 10 judges whether the clutch 26 remains disengaged during the execution of the hill climbing assist control (step S7). If the HCU 10 judges in step S7 that the clutch 26 does not remain disengaged, it determines that the clutch 26 has transitioned to a fully engaged state, which means that there is no need to output a hill climbing assist torque, and stops the hill climbing assist control that was started in step S6 (step S11), and ends this hill climbing assist judgment process.

If the HCU 10 determines in step S7 that the clutch 26 remains disengaged, it determines whether the vehicle speed is less than a predetermined vehicle speed (step S8). If the HCU 10 determines in step S8 that the vehicle speed is not less than the predetermined vehicle speed, i.e., that the vehicle speed is equal to or greater than the predetermined vehicle speed, it stops the hill climbing assist control that was started in step S6 (step S11) and ends this hill climbing assist determination process.

The specified vehicle speed is set to a speed lower than the target vehicle speed of the hybrid vehicle 1. The aforementioned target vehicle speed is, for example, an estimated vehicle speed estimated from the accelerator opening or the gear position, or a set vehicle speed during cruise control or automatic driving. The estimated vehicle speed and the set vehicle speed are both variable values. For this reason, it is preferable that the specified vehicle speed also varies in conjunction with the estimated vehicle speed and the set vehicle speed. For example, the specified vehicle speed can be a vehicle speed that is a specified speed lower than the estimated vehicle speed and the set vehicle speed, or a vehicle speed multiplied by a specified ratio (specified ratio < 100%) to the estimated vehicle speed and the set vehicle speed.

The predetermined vehicle speed may be set to the target vehicle speed of the hybrid vehicle 1. The predetermined vehicle speed may be changed according to the remaining battery capacity of the third power storage device 33. For example, when the remaining battery capacity of the third power storage device 33 is equal to or greater than a predetermined threshold value that is greater than the first threshold value, the predetermined vehicle speed may be set to the target vehicle speed of the hybrid vehicle 1, and when the remaining battery capacity of the third power storage device 33 is equal to or greater than the first threshold value and less than the predetermined threshold value, the predetermined vehicle speed may be set to a speed lower than the target vehicle speed of the hybrid vehicle 1. Furthermore, the predetermined vehicle speed may be set to a fixed value that is determined in advance through experiments, tests, etc.

If the HCU 10 determines in step S8 that the vehicle speed is less than the predetermined vehicle speed, it determines whether the remaining battery charge of the third storage device 33 is equal to or greater than the first threshold (step S9). If the HCU 10 determines in step S9 that the remaining battery charge of the third storage device 33 is not equal to or greater than the first threshold, i.e., that the remaining battery charge of the third storage device 33 is less than the first threshold, it stops the hill climbing assist control that was started in step S6 (step S11) and ends this hill climbing assist determination process.

If the HCU 10 determines in step S9 that the remaining battery capacity of the third storage device 33 is equal to or greater than the first threshold, it determines whether a predetermined time has elapsed since the execution of the hill climbing assist control was started in step S6 (step S10).

If the HCU 10 determines in step S10 that a predetermined time has not elapsed since the execution of the hill climbing assist control was started in step S6, the HCU 10 transitions to step S7 and repeats the processes from step S7 to step S10 again.

If the HCU 10 determines in step S10 that a predetermined time has elapsed since the execution of the hill climbing assist control was started in step S6, the HCU 10 stops the hill climbing assist control that was started in step S6 (step S11) and ends this hill climbing assist determination process.

Next, the flow of the acceleration assist determination process executed by the HCU 10 will be described with reference to FIG. 4. The acceleration assist determination process shown in FIG. 4 is repeatedly executed at a predetermined time interval.

As shown in FIG. 4, the HCU 10 determines whether the acceleration request value for the hybrid vehicle 1 is equal to or greater than a second predetermined value (step S21). The second predetermined value is smaller than the first predetermined value.

If the HCU 10 determines in step S21 that the acceleration request value is not equal to or greater than the second predetermined value, the HCU 10 ends this acceleration assist determination process without executing acceleration assist control. If the HCU 10 determines in step S21 that the acceleration request value is equal to or greater than the second predetermined value, the HCU 10 determines whether the remaining battery capacity of the third storage device 33 is equal to or greater than the second threshold (step S22).

If the HCU 10 determines in step S22 that the remaining battery capacity of the third storage device 33 is not equal to or greater than the second threshold, the HCU 10 ends this acceleration assist determination process without executing acceleration assist control. If the HCU 10 determines in step S22 that the remaining battery capacity of the third storage device 33 is equal to or greater than the second threshold, the HCU 10 determines whether or not the hill climbing assist control or the acceleration assist control is being executed (step S23).

If the HCU 10 determines in step S23 that the hill climbing assist control or the acceleration assist control is being executed, the HCU 10 ends this acceleration assist determination process without executing the acceleration assist control. If the HCU 10 determines in step S23 that the hill climbing assist control or the acceleration assist control is not being executed, the HCU 10 executes the acceleration assist control (step S24) and ends this acceleration assist determination process.

Next, an example of a case where the hill climbing assist control is executed will be described with reference to the time chart in FIG. 5. The time chart in FIG. 5 shows an example of a case where the hybrid vehicle 1 is started from a stop on an uphill road with a predetermined gradient or more, and the execution condition of the hill climbing assist control is satisfied at time t1.

As shown in FIG. 5, when the hybrid vehicle 1 is stopped in an idling state and the driver requests a start at time t1 by depressing the accelerator pedal 8, the engine speed and total torque increase according to the accelerator opening. At this time, the clutch 26 is released from the disengaged state and the engagement state changes toward the semi-engaged state.

After that, at time t2, when the clutch 26 transitions to a half-engaged state, torque begins to be transmitted from the engine-side frictional engagement element 26a to the transmission-side frictional engagement element 26b. As a result, from time t2 onwards, the clutch rotation speed starts to increase, and the difference with the engine rotation speed gradually decreases. The clutch rotation speed is the rotation speed of the transmission-side frictional engagement element 26b.

In addition, after time t2, the total torque of the hill climbing assist torque and the engine torque remains greater than the required driving force.

After that, at time t3, when the difference in rotation speed between the engine rotation speed and the clutch rotation speed becomes less than a set value, the clutch 26 starts to transition from a half-engaged state to a fully-engaged state. This set value is set to a value that reduces the shock when the clutch 26 transitions from a half-engaged state to a fully-engaged state. As a result, compared to when the set value is set to 0, the time it takes for the clutch 26 to transition from a half-engaged state to a fully-engaged state is shortened, and the rise in clutch temperature and the discharge power of the third storage device 33 can be suppressed. Note that this set value can also be set to 0 to eliminate the shock when the clutch 26 transitions from a half-engaged state to a fully-engaged state.

The degree of clutch engagement between time t2 and time t3 is maintained at a predetermined degree of engagement. This degree of clutch engagement is an index showing the degree of engagement of the clutch 26, and when the clutch 26 is in a semi-engaged state, the higher the degree of clutch engagement, the higher the power transmission rate of the clutch 26, and the lower the degree of clutch engagement, the lower the power transmission rate of the clutch 26.

Indicators of the degree of engagement of the clutch 26 can be the distance between the frictional engagement elements 26a and 26b, the amount of drive that drives the clutch 26 (the amount of current or voltage in the case of an electromagnetic clutch, or the amount of pressure oil in the case of a hydraulic clutch), or the clutch capacity.

The predetermined degree of engagement is set to a value at which the rate of temperature rise of the clutch 26 due to friction between the frictional engagement elements 26a and 26b falls below an upper limit value. As a result, between time t2 and time t3, that is, when the difference in rotation speed between the engine rotation speed and the clutch rotation speed exceeds the set value and the rate of rise in the clutch temperature increases, the predetermined degree of engagement is maintained at a constant value, thereby suppressing a sudden rise in the clutch temperature.

The predetermined degree of engagement may be a fixed value determined in advance through experiments, tests, etc., or may be set to a variable value that changes depending on the vehicle state and the external environment. When the predetermined degree of engagement is a variable value, for example, the predetermined degree of engagement may be set to be smaller the greater the difference in rotation speed between the engine rotation speed and the clutch rotation speed, or the predetermined degree of engagement may be set to be smaller the greater the output value of a clutch temperature sensor (not shown) or the clutch temperature (or temperature rise rate) estimated by a clutch temperature estimation unit (not shown).

After that, at time t4, when the clutch 26 transitions from the half-engaged state to the fully-engaged state, the engine speed and the clutch speed are synchronized, and the clutch 26 enters an engaged state, causing the hill climbing assist control to stop.

When the climb assist control is stopped at time t4, the climb assist torque may be immediately set to 0. However, if the climb assist torque is immediately set to 0, and the amount of climb assist torque immediately before time t4 is large, the total torque may suddenly decrease, causing the driver to feel a shock or discomfort due to the torque decrease.

Therefore, even if the hill climbing assist control is stopped, the drive of the motor generator 4 is controlled so that the hill climbing assist torque gradually decreases until time t5. This causes the total torque to gradually decrease as well. As a result, the total torque does not suddenly decrease when the hill climbing assist control is stopped, and shock and discomfort associated with torque decrease can be suppressed.

In addition, the control to gradually reduce the climbing assist torque when the climbing assist control is stopped is only performed when the assist torque amount just before the climbing assist control is stopped is greater than a set value or when the proportion of the assist torque amount in the total torque just before the climbing assist control is stopped is greater than a set value, and the execution may be stopped if the shock or discomfort caused by the torque reduction is slight.
In addition, the control that gradually reduces the climbing assist torque when the climbing assist control is stopped may increase the rate or degree of reduction of the assist torque compared to when the assist torque amount just before the climbing assist control is stopped is smaller than a set value or when the proportion of the assist torque amount in the total torque just before the climbing assist control is stopped is smaller than a set value.

When the hill climbing assist control is stopped, the hill climbing assist torque becomes 0. However, in the following cases, for example, it is preferable to reduce or increase the hill climbing assist torque to the assist torque in another assist control, rather than setting it to 0. When the hill climbing assist torque and the assist torque in another assist control match, the hill climbing assist torque is maintained.

In other words, the period from time t4 to time t5 can be regarded as a transition period in which the hill climbing assist control gradually switches to the other assist control. This prevents the assist torque from suddenly changing when the hill climbing assist control switches to the other assist control, suppressing the shock and discomfort that accompanies a sudden change in the assist torque, and improving the trackability of the total torque to the target torque. In this embodiment, this transition period is set to a constant time, but if the transition period is set longer the greater the torque difference between the hill climbing assist torque and the assist torque in the other assist control, the shock and discomfort that accompanies a sudden change in the assist torque can be further suppressed.

In addition, even if the climbing assist torque is set to 0 without transitioning to another assist control, the transition period can be set longer as the climbing assist torque increases, thereby suppressing shock and discomfort caused by a sudden change in the assist torque.

For example, if the conditions for executing acceleration assist control are met while the climbing assist control is being executed, and it is predicted that the acceleration assist control will be executed immediately after the climbing assist control is stopped, the climbing assist torque is gradually decreased or increased to the acceleration assist torque, and the climbing assist control is stopped when the climbing assist torque matches the acceleration assist torque. Also, if the acceleration assist torque and the climbing assist torque match when the conditions for executing acceleration assist control are met, the climbing assist torque is maintained.

In addition, cases where the execution of acceleration assist control is predicted include, for example, a case where the execution conditions for acceleration assist control are met during hill climbing assist control, or a case where the execution conditions for acceleration assist control are met between the time when hill climbing assist control is stopped and the time when the hill climbing assist torque transitions to zero.

As described above, the assist control device according to this embodiment is configured to execute hill climbing assist control that outputs assist torque from the motor generator 4 to the drive wheels 5 when the execution conditions are met: the road is an uphill road with a gradient of at least a predetermined gradient, the clutch 26 is in a disengaged state, including a half-engaged state, and there is no request for a gear change.

With this configuration, the assist control device according to this embodiment does not execute the climbing assist control when the gradient of the uphill road is small, so it is possible to reduce the power consumption of the third power storage device 33 that supplies power to the motor generator 4. This makes it easier to secure power for outputting the climbing assist torque when the gradient of the uphill road is large, and increases the opportunities for executing the climbing assist torque control.

As a result, the assist control device according to this embodiment can output the necessary climbing assist torque through the climbing assist torque control on steeply inclined uphill roads, thereby reducing the load acting on the friction engagement element 26b on the transmission side of the clutch 26. This makes it possible to reduce the amount of heat generated by the clutch 26. Therefore, since it is not necessary to extend the period during which the clutch 26 is in a half-engaged state in order to reduce the amount of heat generated by the clutch 26, the transition time for transitioning the clutch 26 from a half-engaged state to a fully engaged state can be shortened.

The assist control device according to this embodiment can therefore improve the starting and acceleration performance of the hybrid vehicle 1 on steep gradients while suppressing heat generation from the clutch 26.

The assist control device according to this embodiment stops the hill climbing assist control when the clutch 26 transitions from a non-engaged state to an engaged state, so that the output of unnecessary hill climbing assist torque can be suppressed, and power consumption of the third power storage device 33 can be reduced.

In addition, with the above configuration, the assist control device according to this embodiment minimizes the period during which the hill climbing assist control is executed, suppressing heating of high-voltage components such as the inverter 45 and high-voltage cable 35 connected to the motor generator 4. This makes it possible to prevent the assist torque from being limited due to heating of high-voltage components.

The assist control device according to this embodiment is configured to stop the hill climbing assist control when the vehicle speed reaches or exceeds a predetermined vehicle speed that is lower than the target vehicle speed of the hybrid vehicle.

With this configuration, the assist control device according to this embodiment performs hill climbing assist control even when the clutch 26 is in a half-engaged state until the actual vehicle speed reaches a predetermined vehicle speed, thereby reducing the sluggish feeling when starting off. In addition, after the actual vehicle speed reaches the predetermined vehicle speed, the hill climbing assist control is stopped, thereby reducing unnecessary power consumption. As a result, the opportunities for performing the hill climbing assist control can be increased.

The assist control device according to this embodiment is configured to stop the hill climbing assist control when a predetermined time has elapsed since the start of the hill climbing assist control.

With this configuration, the assist control device according to this embodiment limits the output time of the hill-climbing assist torque, so that the hill-climbing assist torque is not output more than necessary or for a long period of time, thereby reducing the power consumption of the third power storage device 33.

The assist control device according to this embodiment is configured to execute the climbing assist control on the condition that the acceleration demand value becomes equal to or greater than the first predetermined value from a state where the acceleration demand value is less than the first predetermined value after the climbing assist control is stopped.

With this configuration, the assist control device according to this embodiment can suppress the resumption of the climbing assist control immediately after the climbing assist control is stopped, because the climbing assist control is not executed until the acceleration request value becomes equal to or greater than the first predetermined value after it becomes less than the first predetermined value after the climbing assist control is stopped. As a result, the climbing assist torque is not output more than necessary or for a long period of time, and the climbing assist control is not executed continuously, and the power consumption of the third power storage device 33 can be suppressed.

In the assist control device according to this embodiment, the climbing assist control is executed on condition that the remaining battery capacity of the third power storage device 33 is equal to or greater than a first threshold, and the acceleration assist control is executed on condition that the remaining battery capacity of the third power storage device 33 is equal to or greater than a second threshold that is greater than the first threshold.

With this configuration, the assist control device according to this embodiment does not execute acceleration assist control when the remaining battery capacity of the third storage device 33 is less than the second threshold, so that power consumption of the third storage device 33 can be suppressed. Also, for example, when traveling on a flat road where hill climbing assist control is not executed, the execution of acceleration assist control can be limited as described above to increase the opportunities for power generation by the motor generator 4. As a result, the remaining battery capacity of the third storage device 33 can be increased, and the opportunities for executing hill climbing assist control can be increased.

The assist control device according to this embodiment is configured to ensure that the third power storage device 33 has a remaining battery capacity equal to or greater than the first threshold value when it is determined that an uphill road with a gradient of at least a predetermined gradient exists on the travel route from the current location to the destination.

With this configuration, the assist control device according to this embodiment reserves the necessary remaining battery charge in advance when it is known that an uphill road with a gradient of at least a specified level exists on the travel route to the destination, thereby preventing a situation in which the uphill assist control cannot be executed due to insufficient remaining battery charge when the uphill road is reached. As a result, the opportunities for executing the uphill assist control can be increased.

In this embodiment, an example has been described in which acceleration assist control is executed as an assist control other than hill climbing assist control, but this is not limiting, and shift assist control may be executed as another assist control. Shift assist control is a control that suppresses engine torque loss during shifting by outputting shift assist torque from the motor generator 4 while the transmission 3 is shifting and the clutch 26 is in a disengaged state based on a shift request that changes the gear ratio of the transmission 3, such as an upshift request or a downshift request, thereby improving drivability while mitigating discomfort and shift shock felt by the occupants during shifting.

In an example where shift assist control is executed, the HCU 10 executes the shift assist determination process shown in FIG. 6 in addition to the hill climbing assist determination process and acceleration assist determination process of this embodiment. This shift assist determination process is executed repeatedly at a predetermined time interval.

As shown in FIG. 6, the HCU 10 determines whether or not there is a gear shift request (step S31). If the HCU 10 determines in step S31 that there is no gear shift request, the HCU 10 ends this gear shift assistance determination process. If the HCU 10 determines in step S31 that there is a gear shift request, the HCU 10 determines whether or not the remaining battery capacity of the third storage device 33 is equal to or greater than a third threshold (step S32).

The third threshold is set to a value greater than the first threshold and less than the second threshold in this embodiment. Here, the first threshold is a value related to whether or not to execute the hill climbing assist control, and is therefore set to the smallest value among the first, second and third thresholds from the viewpoint of ensuring the power performance of the hybrid vehicle 1. This allows the hill climbing assist control to be executed even when the remaining battery charge is such that other assist controls are not executed.

In contrast, the second and third thresholds have a lower priority than the hill climbing assist control because both the acceleration assist control and the gear shift assist control are controls that are executed from the perspective of improving drivability. For this reason, the second and third thresholds are set to values greater than the first threshold.

If the HCU 10 determines in step S32 that the remaining battery charge of the third storage device 33 is not equal to or greater than the third threshold, the HCU 10 ends this shift assist determination process. If the HCU 10 determines in step S32 that the remaining battery charge of the third storage device 33 is equal to or greater than the third threshold, the HCU 10 determines whether the clutch 26 has changed from an engaged state to a disengaged state (step S33).

If the HCU 10 determines in step S33 that the clutch 26 has not changed from an engaged state to a disengaged state, the HCU 10 ends this shift assist determination process. If the HCU 10 determines in step S33 that the clutch 26 has changed from an engaged state to a disengaged state, the HCU 10 executes shift assist control (step S34) and ends this shift assist determination process.

When the shift assist control is executed, a shift assist torque is output from the motor generator 4 to prevent torque loss during shifting. This prevents torque loss during shifting, improving drivability while mitigating the discomfort and shift shock felt by occupants due to torque loss.

If the conditions for executing the shift assist control are met while the hill climbing assist control is being executed and it is predicted that the shift assist control will be executed immediately after the hill climbing assist control is stopped, the hill climbing assist torque is gradually decreased or increased to the shift assist torque, and the hill climbing assist control is stopped when the shift assist torque matches the shift assist torque. Also, if the shift assist torque and the hill climbing assist torque match when the conditions for executing the shift assist control are met, the hill climbing assist torque is maintained.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

For example, as an assist control other than the above-mentioned hill climbing assist control, sudden acceleration assist control may be executed instead of or in addition to the acceleration assist control. The sudden acceleration assist control is a control that aims to improve drivability by determining that sudden acceleration is required when the amount of change in the acceleration request value, such as the driver's depression speed of the accelerator pedal 8 or the required acceleration, exceeds a threshold value, and generating an assist torque from the motor generator 4 to increase the acceleration of the hybrid vehicle 1. The sudden acceleration assist control is executed under the condition that the remaining battery capacity of the third power storage device 33 is equal to or greater than a fourth threshold value.

In this way, when multiple assist controls can be executed in addition to the hill climbing assist control, it is preferable that the first threshold value for the hill climbing assist control be set to the smallest among the threshold values of the remaining battery capacity of the third storage device 33 that are the execution conditions for these assist controls.

As a result, the smaller the first threshold value, the higher the priority of the hill climbing assist control over other assist controls, while limiting the execution of assist controls other than the hill climbing assist control. This makes it possible to suppress a decrease in the remaining battery capacity of the third storage device 33, while increasing the opportunities to charge the third storage device 33 by making the motor generator 3 function as a generator.

As a result, the starting and acceleration of the hybrid vehicle 1 can be improved even on steep uphill roads where starting or acceleration would be significantly impaired without the assist torque, and the anxiety felt by the driver or passengers due to a significantly long time required for starting or accelerating can be reduced.

Furthermore, among the thresholds of the remaining battery capacity of the third power storage device 33 that are the execution conditions of the assist control, it is preferable to set the third threshold of the shift assist control smaller than the second threshold of the acceleration assist control and the fourth threshold of the rapid acceleration assist control.

As a result, the smaller the third threshold value, the higher the priority given to the hill climbing assist control and the gear change assist control over other assist controls that improve drivability, while limiting the execution of the other assist controls. This increases the opportunities for the hill climbing assist control and the gear change assist control to be executed, making it easier to suppress the anxiety and discomfort felt by the driver when driving on steep uphill roads or when changing gears.

In this embodiment, the situation in which the hill-climbing assist control is executed is described as a case in which the hybrid vehicle 1 starts moving after being stopped on an uphill road with a predetermined gradient or more, but the situation is not limited to this. For example, the hill-climbing assist control may be executed when the clutch 26 is transitioned from a fully engaged state to a half-engaged state to prevent the engine 2 from stalling due to the traveling load on the uphill road while the hybrid vehicle 1 is traveling at a low vehicle speed (very low vehicle speed) on an uphill road.

In this embodiment, a hybrid vehicle using an internal combustion engine as the engine has been described, but the vehicle may also use a second motor generator that generates power using battery power instead of an internal combustion engine as the engine. In this case, it is preferable to install a fourth power storage device that supplies power to the second motor generator and a second inverter that controls the power supplied to the second motor generator in the vehicle.

1 Hybrid vehicle (vehicle)
2 Engine 3 Transmission
4 Motor generator (motor)
5 Drive wheel 8 Accelerator pedal 10 HCU (control unit)
10a Wheel speed sensor 10b Accelerator opening sensor 10c Clutch stroke sensor 10d Crank angle sensor 10e Acceleration sensor 10f Map information acquisition unit 10g Position information acquisition unit 11 ECM
20. ISG
23 Drive shaft 26 Clutch 26a Friction engagement element on engine side 26b Friction engagement element on transmission side 33 Third power storage device (battery)
REFERENCE SIGNS LIST 101 Road surface gradient determination unit 102 Clutch state determination unit 103 Gear change request determination unit 104 Acceleration request determination unit 105 Battery state determination unit 106 Uphill road information acquisition unit 107 Timer

Claims (6)

The engine,
a transmission that changes the speed of the rotation of the engine and transmits it to drive wheels;
a clutch that disconnects or connects a power transmission path between the transmission and the engine;
A motor capable of transmitting power to the drive wheels.
a control unit that executes a hill climbing assist control that outputs an assist torque from the motor to the drive wheels when the execution conditions are satisfied, the execution conditions being that the road is an uphill road with a gradient equal to or greater than a predetermined gradient, the clutch is in a disengaged state including a half-engaged state, and there is no request for a gear change;
The control unit has two conditions: the clutch has transitioned from a disengaged state to an engaged state, and the vehicle speed of the vehicle has become equal to or greater than a predetermined vehicle speed, and the assist control device stops the climbing assist control when at least one of these two conditions is met. The assist control device according to claim 1, characterized in that the predetermined vehicle speed is set to a speed lower than the target vehicle speed of the vehicle. The assist control device according to claim 1 or 2, characterized in that the control unit stops the hill climbing assist control on the condition that a predetermined time has elapsed since the start of execution of the hill climbing assist control. The execution condition further includes that an acceleration request value indicating a degree of an acceleration request for the vehicle is equal to or greater than a predetermined value,
4. The assist control device according to claim 1, wherein the control unit executes the climbing assist control on the condition that, after the climbing assist control is stopped, the acceleration request value changes from a state where the acceleration request value is less than the predetermined value to a state where the acceleration request value is equal to or greater than the predetermined value. The control unit is capable of executing an acceleration assist control in which an acceleration assist torque is output from the motor to the drive wheels in response to an acceleration request for the vehicle,
the hill climbing assist control is executed on the condition that a remaining capacity of a battery that supplies power to the motor is equal to or greater than a first threshold value;
5. The assist control device according to claim 1, wherein the acceleration assist control is executed on the condition that the remaining charge of the battery is equal to or greater than a second threshold value that is greater than the first threshold value. An uphill road information acquisition unit is provided for acquiring uphill road information on a travel route to a destination,
6. The assist control device according to claim 5, wherein when it is determined that an uphill road exists on the driving route to the destination based on the uphill road information acquired by the uphill road information acquisition unit, the control unit ensures that the remaining capacity of the battery is equal to or greater than the first threshold value by the time the vehicle reaches the uphill road from its current position.

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