JP7722009B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device.

In recent years, due to societal demands for low fuel consumption and low exhaust emissions, hybrid vehicles equipped with an engine and a motor as a power source have been attracting attention. Patent Document 1 discloses a drive control device for a hybrid vehicle that switches between EV mode, in which the clutch is disengaged and the vehicle runs on motor power, and HV mode, in which the clutch is engaged and the vehicle runs on at least the engine power of either the engine or the motor. In such vehicles, it is desirable to be able to transition from EV mode to HV mode without causing any discomfort to the driver.

In the system described in Patent Document 1, rather than engaging the clutch immediately after the engine starts, the clutch is fully engaged after the motor-generator rotation speed approaches the engine's ideal fuel-efficient rotation speed. This prevents the engine from revving up while preventing the engine's rotation speed from remaining high, and allows the engine and motor-generator rotation speeds to be smoothly controlled to the engine's ideal fuel-efficient rotation speed without causing any discomfort to the driver.

Patent No. 6070577

In a hybrid vehicle, the motor generator and engine are controlled so that the driver's requested torque is satisfied by the motor torque and engine torque. The hybrid vehicle described in Patent Document 1 switches to HEV mode (HV mode) when the motor torque is no longer able to satisfy the driver's requested torque in EV mode, where the vehicle runs on motor torque. Therefore, immediately after switching to HEV mode, it is desirable to be able to make up for the shortfall in motor torque relative to the driver's requested torque with engine torque. If the engine torque is insufficient immediately after switching to HEV mode, the vehicle's torque will be insufficient relative to the driver's requested torque, and the vehicle's responsiveness to the driver's requested torque will deteriorate.

However, the technology described in Patent Document 1 does not consider how to prevent a deterioration in vehicle responsiveness due to a lack of engine torque immediately after switching to HEV mode.

The present invention therefore aims to provide a vehicle control device that can suppress deterioration in the vehicle's responsiveness to driver-requested torque immediately after switching from EV mode to HEV mode.

In order to solve the above problems, the present invention is provided for a vehicle that is equipped with an engine that generates engine torque, a motor that generates motor torque, a manual transmission that is arranged between the engine and the motor and that changes gear stages by shifting a shift lever, and a clutch that is arranged between the engine and the manual transmission and that is disengaged or engaged by operation of a clutch actuator, and that provides an EV mode in which the engine is stopped, the clutch is disengaged, and the vehicle travels while satisfying the driver's requested torque with the motor torque, and a EV mode in which the engine is operated, the clutch is engaged, and the vehicle travels while satisfying the driver's requested torque with at least the engine torque or the motor torque. A control device for a vehicle has an HEV mode in which the vehicle runs while satisfying the driver's required torque, and a control unit that switches to the HEV mode when the driver's required torque can no longer be satisfied with the motor torque in the EV mode, wherein the control unit initiates starting of the engine when a predetermined operation is performed, even during the EV mode, that involves at least one of the shift operation and clutch operation on the clutch pedal, and that is expected to cause the driver's required torque to no longer be satisfied with the motor torque , and the predetermined operation is the shift operation to downshift to a gear position that is two or more steps lower .

In this way, the present invention provides a vehicle control device that can suppress deterioration in the vehicle's responsiveness to the driver's requested torque immediately after switching from EV mode to HEV mode.

FIG. 1 is a diagram showing the configuration of a vehicle equipped with a vehicle control device according to a first or second embodiment of the present invention. FIG. 2 is a timing chart showing the transition of the vehicle state when starting the engine in the vehicle control device according to the first embodiment of the present invention. FIG. 3 is a timing chart showing the transition of the vehicle state when starting the engine in the vehicle control device according to the second embodiment of the present invention. FIG. 4 is a timing chart showing the transition of the vehicle state when the engine start is not initiated in the vehicle control device according to the second embodiment of the present invention. FIG. 5 is a diagram showing a method for predicting the accelerator opening in a vehicle control device according to a second embodiment of the present invention. FIG. 6 is a timing chart showing the transition of the vehicle state of a vehicle control device according to a comparative example.

A vehicle control device according to one embodiment of the present invention is mounted on a vehicle that includes an engine that generates engine torque, a motor that generates motor torque, a manual transmission that is positioned between the engine and the motor and changes gears in response to a shift lever shift operation, and a clutch that is positioned between the engine and the manual transmission and is disengaged or engaged by the operation of a clutch actuator. The vehicle has two modes: an EV mode in which the engine is stopped, the clutch is disengaged, and the vehicle travels while satisfying the driver's requested torque with motor torque; and an HEV mode in which the engine is operated, the clutch is engaged, and the vehicle travels while satisfying the driver's requested torque with at least the engine torque and the driver's requested torque with the engine torque. The vehicle control device includes a control unit that switches to HEV mode when the driver's requested torque can no longer be satisfied with the motor torque in EV mode. The control unit is characterized in that, even in EV mode, if a predetermined operation involving at least one of a shift operation or clutch operation on the clutch pedal is performed that is expected to result in the driver's requested torque being no longer able to be satisfied with the motor torque, the control unit initiates engine start-up.

As a result, a vehicle control device according to one embodiment of the present invention can suppress deterioration in the vehicle's responsiveness to the driver's requested torque immediately after switching from EV mode to HEV mode.

A vehicle equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the rotational speed used in the following description refers to the rotational speed (rpm).

In FIG. 1, a vehicle 1 according to one embodiment of the present invention includes an engine 2, a motor generator 3 serving as a motor for driving, a manual transmission 4, a differential 5, drive wheels 6, and an ECU (Electronic Control Unit) 10 serving as a control unit.

Engine 2 has multiple cylinders. In this embodiment, engine 2 is configured to perform a series of four strokes for each cylinder: an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. Engine 2 generates engine torque.

An ISG (Integrated Starter Generator) 20 is connected to the engine 2. The ISG 20 is connected to the crankshaft of the engine 2 via a belt 21 or the like. 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 into electric power.

The motor generator 3 functions as an electric motor that generates driving force for the vehicle using power supplied from the battery 31 via the inverter 30, and as a generator that generates regenerative power using the rotational force (reverse driving force) input from the drive wheels 6 via the differential 5. The motor generator 3 constitutes the motor in the present invention and generates motor torque.

Under the control of the ECU 10, the inverter 30 converts the DC power supplied from the battery 31 into three-phase AC power and supplies it to the motor generator 3, and also converts the three-phase AC power generated by the motor generator 3 into DC power to charge the battery 31. The battery 31 is composed of a secondary battery, such as a lithium-ion battery.

The manual transmission 4 is disposed between the engine 2 and the motor generator 3. The manual transmission 4 is mechanically connected to the shift lever 40. The gear positions of the manual transmission 4 are changed by shifting the shift lever 40.

The manual transmission 4 changes the rotation input from the engine 2 to the input shaft 8 via the clutch 7 at a gear ratio corresponding to one of multiple gear stages and outputs it from the output shaft 9. In this embodiment, the manual transmission 4 is configured as a parallel shaft gear type manual transmission.

The output shaft 9 of the manual transmission 4 is connected to the motor generator 3. The output shaft 3A of the motor generator 3 is connected to the left and right drive wheels 6 via the differential 5. In this way, the vehicle 1 is equipped with the motor generator 3 between the manual transmission 4 and the differential 5. The vehicle 1 is configured as a hybrid vehicle that can run using the driving force of at least one of the engine 2 and the motor generator 3.

The gears that can be achieved with the manual transmission 4 include forward gears ranging from a low 1st gear to a high 5th gear, and a reverse gear. The number of driving gears varies depending on the specifications of the vehicle 1 and is not limited to the above-mentioned 1st to 5th gears.

The gears in the manual transmission 4 are changed according to the operating position of the shift lever 40 operated by the driver. The operating positions of the shift lever 40 include positions corresponding to first through fifth gears, a position corresponding to a reverse gear, and a position corresponding to a neutral state in which no gear is configured. These positions are arranged to form a so-called H-shaped shift pattern. The gears in the manual transmission 4 are changed when the driver's operation of the shift lever 40 is mechanically transmitted to the transmission mechanism via a transmission mechanism such as a cable.

The manual transmission 4 is provided with a shift position sensor 41, which detects the gear position (including the neutral position) of the manual transmission 4. The shift position sensor 41 is connected to the ECU 10 and transmits the detection results to the ECU 10.

In this embodiment, the shift lever 40 is mechanically connected to the manual transmission 4, and no control intervention by the ECU 10 occurs, so the operating position of the shift lever 40 matches the gear position of the manual transmission 4. Therefore, a shift position sensor 41 may be provided on the shift lever 40 instead of the manual transmission 4, and the shift position sensor 41 may detect the operating position of the shift lever 40 and send it to the ECU 10.

A clutch 7 is provided in the power transmission path between the engine 2 and the manual transmission 4. The clutch 7 is a by-wire clutch that is disengaged or engaged by the operation of a clutch actuator 70, which will be described later. The clutch 7 may be, for example, a dry single-plate friction clutch. The engine 2 and manual transmission 4 are connected via the clutch 7.

In this way, the manual transmission 4 is configured so that power is transmitted from the engine 2 to the input shaft 8 via the clutch 7, and gears can be changed by shifting. The clutch 7 is equipped with a clutch disc, and the clutch disc and the input shaft 8 of the manual transmission 4 are interconnected and rotate integrally. Therefore, the rotational speed of the clutch disc is equal to the rotational speed of the input shaft 8 of the manual transmission 4.

The clutch 7 is operated by a clutch actuator 70 and can be switched between an engaged state in which power is transmitted between the engine 2 and the manual transmission 4, a disengaged state in which power is not transmitted, and a half-clutch state in which torque is transmitted with a rotational speed difference. The clutch actuator 70 is connected to and controlled by the ECU 10.

The clutch 7 is provided with a clutch rotation speed sensor 43. The clutch rotation speed sensor 43 detects the rotation speed of the clutch disc of the clutch 7 (hereinafter also referred to as clutch rotation speed). The clutch rotation speed sensor 43 is connected to the ECU 10 and transmits the detection results to the ECU 10.

The ECU 10 controls the clutch actuator 70 in accordance with the amount of depression of the clutch pedal 71 operated by the driver, and controls the clutch 7 so that it operates in the same way as a manual clutch. The ECU 10 also controls the clutch actuator 70 regardless of the driver's operation of the clutch pedal 71, and can change the state of the clutch 7.

More specifically, in the HEV mode described below, the ECU 10 controls the clutch actuator 70 in accordance with the depression amount of the clutch pedal 71, and in the EV mode described below, the ECU 10 controls the clutch actuator 70 to maintain the clutch 7 in an released state regardless of the operation of the clutch pedal 71. In this way, the clutch 7 is released or engaged by the drive of the clutch actuator 70 in accordance with the clutch operation of the clutch pedal 71 or a control command from the ECU 10. Therefore, the clutch 7 is not mechanically connected to the clutch pedal 71, but is a by-wire clutch that is driven via an electrical signal.

The amount of depression of the clutch pedal 71 is detected by a clutch pedal sensor 72. The clutch pedal sensor 72 is connected to the ECU 10 and detects the amount of depression of the clutch pedal 71 as the clutch pedal stroke amount, and sends a signal corresponding to that clutch pedal stroke amount to the ECU 10.

In this embodiment, the load from the clutch 7 (the restoring force of a diaphragm spring, not shown) does not act on the clutch pedal 71, so the driver cannot feel the operation of the clutch pedal 71 (pressure). Therefore, the clutch pedal 71 is provided with a pseudo-load device 71A, which applies a pseudo-load to the clutch pedal 71 that simulates the load that occurs when the clutch pedal 71 is operated.

The vehicle 1 is equipped with an accelerator pedal 90 operated by the driver. The amount of depression of the accelerator pedal 90 is detected by an accelerator position sensor 91. The accelerator position sensor 91 is connected to the ECU 10 and detects the amount of depression of the accelerator pedal 90 as the accelerator position, and transmits a signal corresponding to the accelerator position to the ECU 10.

The vehicle 1 is equipped with a brake pedal 92 that is operated by the driver. The amount of depression of the brake pedal 92 is detected by a brake pedal sensor 93. The brake pedal sensor 93 is connected to the ECU 10 and transmits a signal to the ECU 10 corresponding to the amount of depression of the brake pedal 92.

The ECU 10 is 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, input ports, and output ports.

The ROM of the computer unit stores various constants, maps, etc., as well as programs that cause the computer unit to function as ECU 10. In other words, the CPU uses RAM as a work area to execute the programs stored in ROM, causing the computer unit to function as ECU 10 in this embodiment.

In addition to the sensors mentioned above, a vehicle speed sensor 11 is connected to the ECU 10. The vehicle speed sensor 11 detects the speed of the vehicle 1 and transmits the detection result to the ECU 10.

The ECU 10 switches the driving mode of the vehicle 1. The ECU 10 has EV mode, HEV mode, and other driving modes, and switches between EV mode and HEV mode.

EV mode is a driving mode in which the engine 2 is stopped, the clutch 7 is disengaged, and the vehicle 1 is driven by the motor torque of the motor generator 3, satisfying the driver's requested torque. In EV mode, the engine 2 is not operating, so the engine speed is maintained at zero. Also, in EV mode, the clutch 7 is disengaged, so the engine 2 is prevented from rotating along with the motor generator 3.

Specifically, in EV mode, regardless of whether the driver operates the clutch pedal 71, the actual clutch position of the clutch 7 (the actual position of the clutch 7) is maintained in the disengaged position, and power transmission between the engine 2 and the manual transmission 4 is cut off.

HEV mode is a driving mode in which the engine 2 is operated, the clutch 7 is engaged, and the driver's requested torque is satisfied by at least the engine torque of the engine 2 and the motor torque of the motor generator 3, causing the vehicle 1 to travel. In other words, in HEV mode, the vehicle travels using only the engine torque, or using both the engine torque and the motor torque.

If the motor torque is no longer able to satisfy the driver's requested torque while driving in EV mode, the ECU 10 switches from EV mode to HEV mode. In more detail, the ECU 10 switches to HEV mode when the motor outputtable torque, which is the maximum motor torque that can be generated by the motor generator 3 and is determined based on the state of charge of the battery 31, is no longer able to satisfy the driver's requested torque (when the driver's requested torque increases and exceeds the motor outputtable torque).

When switching from EV mode to HEV mode based on an increase in driver-requested torque, immediately after switching to HEV mode, ECU 10 controls motor generator 3 and engine 2 so that engine torque compensates for the shortfall in motor torque relative to driver-requested torque.

In this embodiment, the torque acting on the output shaft 3A of the motor generator 3 is referred to as the axle torque. Furthermore, in a vehicle 1 equipped with a manual transmission 4 and a clutch 7, the driver-requested torque is determined based not only on the accelerator opening but also on the amount of depression of the clutch pedal 71.

For example, when the clutch pedal 71 is not depressed (depression amount is 0%), the magnitude of the accelerator opening indicates the magnitude of the driver-requested torque. However, when the clutch pedal 71 is depressed to 50% (assuming the clutch 7 engagement degree and transmission torque are 50%), the driver-requested torque is 50% of the value when the clutch pedal 71 is not depressed. Therefore, in this specification, the driver-requested torque determined from the accelerator opening and clutch pedal depression amount is referred to as the post-clutch-limited axle-requested torque.

If the engine 2 has not yet completed starting (is in the process of starting) immediately after switching to HEV mode, the engine torque cannot be used as a driving source for driving, and the engine torque cannot fully compensate for the shortfall in motor torque relative to the driver-requested torque. In this case, the responsiveness of the vehicle 1 to the driver-requested torque may deteriorate. This state is called "hesitation" because to the driver, it feels like the vehicle 1 is hesitant to accelerate. Because the occurrence of hesitation impairs drivability, it is desirable to suppress it.

The period from when engine 2 starts (cranking by a starter, not shown) until engine torque can be used as a driving source for traveling includes the period from when engine 2 starts until starting is completed (starting period) and the period during which engine speed is increased to match clutch speed and adjusted (rotation adjustment period). Furthermore, adjusting the engine speed to match the clutch speed begins on the condition that engine 2 starting is complete.

The comparative example shown in Figure 6 is a timing chart illustrating a case where the vehicle's responsiveness to the driver's requested torque deteriorates immediately after switching to HEV mode. Figure 6 shows the transition in vehicle state when the driver downshifts gears and presses the accelerator pedal 90 heavily to request greater vehicle acceleration while in EV mode, causing the vehicle to switch to HEV mode.

The vertical axis of Figure 6 represents, from top to bottom, the gear position (referred to as "gear position" in the figure), clutch rotation speed, engine rotation speed, clutch pedal 71 depression state (referred to as "clutch pedal" in the figure), actual clutch position, accelerator opening, axle torque requirement after clutch limit, motor torque (referred to as "motor output torque" in the figure), axle torque, and driving mode, while the horizontal axis represents time. Note that the axle torque requirement after clutch limit is represented by a solid line, the motor torque is represented by a dashed line, and the axle torque is represented by a dotted line.

In the initial state before time t11, the vehicle 1 is traveling in EV mode. In this EV mode, the clutch pedal 71 is in the released position (labeled "released" in the figure), where it is not depressed, but the actual clutch position is maintained in the open position (labeled "open" in the figure) by the drive of the clutch actuator 70. Furthermore, because the engine 2 is not operating, the engine speed is maintained at zero. Furthermore, the gear is set to fifth gear, and the accelerator opening is maintained at a constant opening (e.g., 50%). Furthermore, the axle request torque after clutch limiting, which is the driver request torque, is satisfied by the motor torque, and the value of the axle torque is the same as the motor torque.

Then, at time t11, the driver depresses the clutch pedal 71 to the fully depressed press position (denoted as "press" in the figure) as a downshift operation to accelerate the vehicle 1, shifts the gear to neutral at time t12, shifts the gear to third gear (or fourth gear) at time t13, and begins to return the clutch pedal 71 to the release position, finishing returning the clutch pedal 71 to the release position at time t15.

Then, at time t14, while the clutch pedal 71 is being released, the motor torque reaches the motor's outputtable torque, and the axle torque requirement after clutch limitation can no longer be met by the motor torque alone. Therefore, at time t14, the vehicle mode is switched from EV mode to HEV mode, and engine 2 begins to start (crank).

Then, at time t15, starting of engine 2 is completed. After starting of engine 2 is completed, the engine speed is increased to match the clutch speed. Then, at time t16, the engine speed matches the clutch speed, and speed matching is completed.

Then, at time t17, the clutch 7 is engaged by driving the clutch actuator 70, and the actual clutch position is set to the engaged position (marked "closed" in the diagram). As a result, at time t17, the shortfall in motor torque relative to the axle request torque after clutch limiting can be compensated for by engine torque.

Therefore, in the comparative example of Figure 6, from the time when the mode is switched to HEV mode at time t14 until the clutch 7 is fully engaged at time t17, engine torque cannot be used as a driving source for driving, so the axle torque is insufficient relative to the axle request torque after the clutch is limited, and the responsiveness of the vehicle 1 to the driver's request torque deteriorates. In other words, a hedging occurs immediately after switching to HEV mode.

In this embodiment, therefore, in order to prevent a deterioration in the vehicle's responsiveness to the driver's requested torque immediately after switching from EV mode to HEV mode, if the driver performs an operation that is expected to result in a switch to HEV mode, the engine 2 is started in advance prior to switching to HEV mode. An operation that is expected to result in a switch to HEV mode is a predetermined operation that is expected to result in the motor torque being unable to satisfy the driver's requested torque.

Here, a specific operation that is expected to result in the motor torque being unable to satisfy the driver's requested torque is a driving operation that requires high acceleration, such as for overtaking a preceding vehicle. An example of a driving operation that requires high acceleration is downshifting two or more gears to a lower gear (for example, a jump shift from 5th gear to 3rd gear) and depressing the accelerator pedal 90. In this embodiment, the operation of the ECU 10 when this operation is performed is described. Note that another example of a driving operation that requires high acceleration is downshifting one gear to a lower gear (for example, from 5th gear to 4th gear) and depressing the accelerator pedal 90 more deeply; the operation of the ECU 10 when this operation is performed is described in the second embodiment.

In this embodiment, even in EV mode, the ECU 10 initiates starting of the engine 2 when a predetermined operation is performed that involves at least one of a shift operation and a clutch operation on the clutch pedal 71, and that is expected to result in the motor torque being unable to satisfy the driver's requested torque. The predetermined operation is a shift operation that downshifts to a gear that is two or more steps lower. For example, the predetermined operation is a shift operation that downshifts from fifth gear to third gear.

However, even if a specified operation involving at least one of a shift operation and a clutch operation on the clutch pedal 71 is being performed, if a brake operation is also being performed, this is a situation in which the driver is performing an operation to decelerate the vehicle 1, and it is not an operation that is expected to result in the motor torque being unable to satisfy the driver's requested torque.

Therefore, even if a predetermined operation is performed during EV mode, the ECU 10 will not initiate starting of the engine 2 if the brake pedal 92 is also being operated.

The transition of vehicle state during operation of the vehicle control device according to this embodiment, configured as described above, will be described with reference to the timing chart in Figure 2. Figure 2 shows the transition of vehicle state when, in EV mode, the driver downshifts the gear by two or more steps to a lower gear in order to accelerate the vehicle more rapidly, and depresses the accelerator pedal 90, causing the engine 2 to start prior to switching to HEV mode. The vertical axis of Figure 2, from top to bottom, represents the gear, clutch rotation speed, engine rotation speed, clutch pedal 71 depression state (referred to as "clutch pedal" in the figure), actual clutch position, accelerator opening, axle torque demand after clutch limit, motor torque (referred to as "motor output torque" in the figure), axle torque, and driving mode, while the horizontal axis represents the transition of time. Note that the axle torque demand after clutch limit is represented by a solid line, the motor torque by a dashed line, and the axle torque by a dashed line.

In the initial state before time t21, the vehicle 1 is traveling in EV mode. In this EV mode, the clutch pedal 71 is not depressed and is in the released position (labeled "released" in the figure), but the actual clutch position is maintained in the open position (labeled "open" in the figure) by the drive of the clutch actuator 70. Furthermore, because the engine 2 is not operating, the engine speed is maintained at zero. Furthermore, the gear position is set to fifth gear, and the accelerator opening is maintained at a constant opening (e.g., 50%). Furthermore, the axle request torque after clutch limiting, which is the driver request torque, is satisfied by the motor torque, and the value of the axle torque is the same as the motor torque.

Then, at time t21, the driver depresses the clutch pedal 71 to the press position (denoted as "press" in the figure), which is the fully depressed position, as a downshift operation to accelerate the vehicle 1, shifts the gear from fifth gear to neutral at time t22, shifts the gear from neutral to third gear at time t23, and begins to return the clutch pedal 71 to the release position, finishing returning the clutch pedal 71 to the release position at time t25.

Then, at time t24, while the clutch pedal 71 is being released, the motor torque reaches the motor's outputtable torque, and the axle torque requirement after clutch limitation can no longer be met by motor torque alone. Therefore, at time t24, the ECU 10 switches from EV mode to HEV mode.

At time t23, which is the timing before switching to HEV mode, the ECU 10 starts the engine 2 (referred to as cranking in the figure) in response to the gear shift from neutral to third gear, prior to switching to HEV mode.

Then, at time t24, starting of engine 2 is completed. Then, as starting of engine 2 is completed, ECU 10 increases the engine speed to match the clutch speed. Then, at time t25, the engine speed matches the clutch speed, and speed matching is completed.

Then, at time t26, the ECU 10 drives the clutch actuator 70 to engage the clutch 7. This causes the actual clutch position to be set to the engaged position (denoted as closed in the diagram). By setting the clutch position to the engaged position, at time t26, the shortfall in motor torque relative to the axle request torque after clutch limiting can be compensated for by engine torque.

Therefore, in this embodiment, the period in which the hedging occurs immediately after switching to HEV mode does not include the period from the start of engine 2 startup (time t23) to its completion (time t24), but only the period from the start of engine 2 rotation matching (time t24) to its completion (time t25). This makes it possible to suppress a deterioration in the responsiveness of vehicle 1 to driver-requested torque immediately after switching from EV mode to HEV mode.

As described above, in this embodiment, even in EV mode, the ECU 10 initiates starting of the engine 2 when a predetermined operation is performed that involves at least one of a shift operation and a clutch operation on the clutch pedal 71, and which is expected to result in the motor torque being unable to satisfy the driver's requested torque.

As a result, if the driver performs a specific operation that is expected to result in the motor torque being unable to satisfy the driver's requested torque, engine 2 will be started in advance before switching to EV mode.

As a result, engine 2 startup can be completed when switching to EV mode, and the shortfall in motor torque relative to the driver's requested torque immediately after switching to EV mode can be compensated for by engine torque. This reduces the amount and duration of engine torque shortfall immediately after switching to EV mode, thereby suppressing the occurrence of so-called hedging.

As a result, deterioration in the vehicle's responsiveness to the driver's requested torque immediately after switching from EV mode to HEV mode can be suppressed.

In this embodiment, the specified operation is a downshift operation to a gear that is two or more steps lower.

As a result, if the driver desires greater acceleration of the vehicle 1, disengages the clutch 7, downshifts from fifth gear to third gear, and engages the clutch while depressing the accelerator pedal 90, the engine 2 will begin to start when the downshift to third gear is completed. Therefore, the engine 2 can be fully started when the mode is switched to HEV mode based on the engagement of the clutch 7.

This prevents the vehicle's responsiveness to the driver's requested torque from deteriorating immediately after switching from EV mode to HEV mode.

In addition, in this embodiment, even if a predetermined operation is performed during EV mode, the ECU 10 will not initiate starting of the engine 2 if the brake pedal 92 is also being operated to brake.

In this way, downshifting accompanied by braking is not an operation for accelerating the vehicle, but an operation for transitioning to a stop, and since it is not expected that an increase in driver-requested torque will result in a transition to HEV mode, unnecessary starting of engine 2 can be avoided, thereby avoiding a deterioration in fuel economy.

Next, we will explain a vehicle control device according to a second embodiment. In this embodiment, the operation of the ECU 10 in the vehicle 1 shown in Figure 1 is partially different. Below, we will explain the differences from the first embodiment.

Driving operations that are expected to result in a switch to HEV mode include when, while driving in EV mode, the driver performs driving operations that require high acceleration, such as to overtake a leading vehicle. Driving operations that require high acceleration include downshifting by one gear to a lower gear (for example, from 5th gear to 4th gear) and depressing the accelerator pedal 90 more firmly.

In this embodiment, the predetermined operation is defined as the simultaneous clutch operation and accelerator operation of the accelerator pedal 90 by an amount equal to or greater than a predetermined threshold.

Here, the driver may operate the accelerator pedal 90 by an amount equal to or greater than a predetermined threshold, not to accelerate the vehicle 1 but to match the engine speed during a downshift. For example, during a downshift, the driver may briefly depress the accelerator pedal 90 (blipping) to match the engine speed to the clutch speed. This blipping is intended to smoothly shift gears in the manual transmission 4, not to accelerate the vehicle 1. In addition, in the vehicle 1 of this embodiment, the engine 2 is stopped during EV mode, making blipping unnecessary, but unnecessary blipping may occur out of the driver's habit.

Therefore, even if a predetermined operation is performed during EV mode, the ECU 10 will not initiate starting of the engine 2 if the amount of accelerator operation remains above a predetermined threshold for less than a predetermined time.

The transition of vehicle state during operation of the vehicle control device according to this embodiment, configured as described above, will be described with reference to the timing chart in Figure 3. Figure 3 shows the transition of vehicle state when, in EV mode, the driver downshifts to a gear one step lower in order to accelerate the vehicle more rapidly and deeply depresses the accelerator pedal 90, causing the engine 2 to start prior to switching to HEV mode. The vertical axis of Figure 3 represents, from top to bottom, the gear, clutch rotation speed, engine rotation speed, clutch pedal 71 depression state (referred to as "clutch pedal" in the figure), actual clutch position, accelerator opening, axle torque demand after clutch limit, motor torque (referred to as "motor output torque" in the figure), axle torque, and driving mode, while the horizontal axis represents the transition of time. Note that the axle torque demand after clutch limit is represented by a solid line, the motor torque by a dashed line, and the axle torque by a dashed line.

In the initial state before time t31, the vehicle 1 is running in EV mode. In this EV mode, the clutch pedal 71 is not depressed and is in the released position (labeled "released" in the diagram), but the actual clutch position is maintained in the open position (labeled "open" in the diagram) by the drive of the clutch actuator 70. Furthermore, because the engine 2 is not operating, the engine speed is maintained at zero. Furthermore, the gear position is set to fifth gear, and the accelerator opening is maintained at a constant opening (e.g., 50%). Furthermore, the axle request torque after clutch limiting, which is the driver request torque, is satisfied by the motor torque, and the value of the axle torque is the same as the motor torque.

Then, at time t31, the driver depresses the clutch pedal 71 to the fully depressed press position (denoted as "press" in the figure) as a downshift operation to accelerate the vehicle 1, shifts the gear from fifth gear to neutral at time t32, shifts the gear from neutral to fourth gear at time t34, and begins to return the clutch pedal 71 to the release position, finishing returning the clutch pedal 71 to the release position at time t37.

Then, at time t35, while the clutch pedal 71 is being released, the motor torque reaches the motor's outputtable torque, and the axle torque requirement after clutch limitation can no longer be met by the motor torque alone. Therefore, at time t35, the ECU 10 switches from EV mode to HEV mode.

At time t33, which is the timing before switching to HEV mode, the accelerator opening has increased to or above the predetermined accelerator opening threshold. Therefore, because the clutch operation and the accelerator operation of the accelerator pedal 90 to an amount greater than or equal to the predetermined threshold were performed simultaneously, the ECU 10 begins starting the engine 2 (referred to as cranking in the figure) at time t33.

After that, engine 2 starts up, and at time t36, the engine speed matches the clutch speed, completing rotation speed matching.

Then, at time t37, the ECU 10 drives the clutch actuator 70 to engage the clutch 7. This brings the actual clutch position to the engaged position (denoted as "closed" in the diagram). Therefore, at time t37, the shortfall in motor torque relative to the axle request torque after clutch limiting can be compensated for by engine torque.

Therefore, in this embodiment, the period in which the hedging occurs immediately after switching to HEV mode does not include the period from the start of engine 2 startup (time t33) to the timing of switching to HEV mode (time t35), but only the period from the timing of switching to HEV mode (time t35) to the completion of engine 2 rotation matching (time t37). This makes it possible to suppress a deterioration in the responsiveness of vehicle 1 to driver-requested torque immediately after switching from EV mode to HEV mode.

Figure 4 shows the transition in vehicle state when the driver downshifts to a gear one step lower and blips the accelerator pedal 90 while coasting in EV mode in order to decelerate the vehicle. The vertical axis of Figure 4, from top to bottom, represents the gear, clutch rotation speed, engine rotation speed, clutch pedal 71 depression state (referred to as clutch pedal in the figure), actual clutch position, accelerator opening, axle torque demand after clutch limit, motor torque (referred to as motor output torque in the figure), axle torque, and driving mode, while the horizontal axis represents the transition over time. The axle torque demand after clutch limit is represented by a solid line, the motor torque by a dashed line, and the axle torque by a dashed line.

In the initial state before time t41, the vehicle 1 is traveling in EV mode. In this EV mode, the clutch pedal 71 is not depressed and is in the released position (labeled "released" in the diagram), but the actual clutch position is maintained in the open position (labeled "open" in the diagram) by the drive of the clutch actuator 70. Furthermore, because the engine 2 is stopped, the engine speed is maintained at zero. Furthermore, the gear position is set to fifth gear, and the accelerator opening is maintained at a constant opening (e.g., 0%). Furthermore, the axle request torque after clutch limiting, which is the driver request torque, is satisfied by the motor torque, and the value of the axle torque is the same as the motor torque.

Then, in order to decelerate the vehicle 1, the driver begins to depress the clutch pedal 71 to the press position (denoted as "press" in the figure) at time t41, finishes depressing the clutch pedal 71 at time t42, shifts the gear from fifth gear to neutral at time t43, shifts the gear from neutral to fourth gear at time t44, and begins to return the clutch pedal 71 to the release position, finishing returning the clutch pedal 71 to the release position at time t46.

Furthermore, at time t44, when the gear is still in neutral, the driver's blipping causes the accelerator opening to exceed the accelerator opening threshold for a short period of time. From time t44, the accelerator opening remains above the accelerator opening threshold for a period T1 that is shorter than the predetermined time.

As shown in Figure 4, in EV mode, the specified operations of clutch operation and accelerator operation of the accelerator pedal 90 by an amount equal to or greater than a specified threshold are simultaneously performed. However, because the amount of accelerator operation equal to or greater than the specified threshold is less than the specified time, engine 2 does not start.

Here, the method for detecting the accelerator opening (amount of depression of the accelerator pedal 90) is a "look-ahead" method that estimates the accelerator opening after a desired look-ahead period, and the "look-ahead value" obtained by this look-ahead method can be used as the value of the accelerator opening after the look-ahead period from the present time. A known method can be used to estimate the look-ahead value of the accelerator opening.

The method shown in Figure 5 can be used to estimate the accelerator pedal position look-ahead value. In Figure 5, the vertical axis represents accelerator pedal position, and the horizontal axis represents time. As shown in Figure 5, the estimated accelerator pedal position at point P5, a desired look-ahead period from current point P4, can be calculated by multiplying the average change in accelerator pedal position (%/ms) between points P1, P2, and P3 over a predetermined period (30 ms in Figure 5) prior to current point P4 by the look-ahead period, and adding this multiplied value to the accelerator pedal position at current point P4. By determining whether to initiate engine 2 start based on the look-ahead value of accelerator pedal position instead of the actual accelerator pedal position, the driver's intention can be detected at an earlier timing, allowing engine 2 start-up to be initiated at an earlier timing, thereby further reducing the occurrence of hesitation.

As described above, in this embodiment, the predetermined operation is the simultaneous clutch operation and accelerator operation of the accelerator pedal 90 by an amount equal to or greater than a predetermined threshold.

As a result, if the driver desires to accelerate the vehicle 1, releases the clutch, downshifts from fifth gear to fourth gear, and engages the clutch 7 while pressing the accelerator pedal 90 deeply beyond a predetermined threshold, the engine 2 will begin to start when the accelerator pedal 90 is pressed beyond the predetermined threshold. Therefore, the engine 2 can be fully started when the vehicle is switched to HEV mode based on the clutch 7 being engaged.

In addition, in this embodiment, even if a predetermined operation is performed during EV mode, the ECU 10 will not initiate starting of the engine 2 if the amount of accelerator operation remains equal to or greater than a predetermined threshold for less than a predetermined time.

As a result, blipping, which is the act of depressing the accelerator pedal 90 for a short period of time during a downshift, is not an act to accelerate the vehicle 1, but an act to smoothly change gears, and since it is not expected that an increase in driver-requested torque will result in a transition to HEV mode, it is possible to avoid a deterioration in fuel efficiency due to unnecessary starting of the engine 2.

While embodiments of the present invention have been disclosed, it will be apparent to those skilled in the art that modifications may be made without departing from the scope of the present invention. All such modifications and equivalents are intended to be encompassed by the following claims.

1 Vehicle 2 Engine 3 Motor generator (motor)
4 Manual transmission 7 Clutch 10 ECU (control unit)
40 Shift lever 70 Clutch actuator 71 Clutch pedal 90 Accelerator pedal 92 Brake pedal

Claims (4)

an engine that generates engine torque;
a motor that generates a motor torque;
a manual transmission disposed between the engine and the motor, the manual transmission being adapted to change gear positions by a shift operation on a shift lever;
a clutch disposed between the engine and the manual transmission, the clutch being disengaged or engaged by operation of a clutch actuator;
an EV mode in which the engine is stopped, the clutch is released, and the vehicle travels while satisfying the driver's requested torque with the motor torque;
an HEV mode in which the engine is operated, the clutch is engaged, and the driver requested torque is satisfied by at least the engine torque of the engine torque and the motor torque ;
A control device for a vehicle including a control unit that switches to the HEV mode when the driver requested torque cannot be satisfied by the motor torque in the EV mode,
The control unit
Even during the EV mode, when a predetermined operation is performed that involves at least one of the shift operation and the clutch operation on the clutch pedal and that is expected to cause the motor torque to be unable to satisfy the driver's requested torque, the engine is started ,
10. A vehicle control device , wherein the predetermined operation is a shift operation for downshifting to a gear position that is two or more steps lower . The control unit
2. The vehicle control device according to claim 1, wherein even if the predetermined operation is performed during the EV mode, if a brake pedal operation is also performed, the engine start is not initiated . an engine that generates engine torque;
a motor that generates a motor torque;
a manual transmission disposed between the engine and the motor, the manual transmission being adapted to change gear positions by a shift operation on a shift lever;
a clutch disposed between the engine and the manual transmission, the clutch being disengaged or engaged by operation of a clutch actuator;
an EV mode in which the engine is stopped, the clutch is released, and the vehicle travels while satisfying the driver's requested torque with the motor torque;
an HEV mode in which the engine is operated, the clutch is engaged, and the driver requested torque is satisfied by at least the engine torque of the engine torque and the motor torque;
A control device for a vehicle including a control unit that switches to the HEV mode when the driver requested torque cannot be satisfied by the motor torque in the EV mode,
The control unit
Even during the EV mode, when a predetermined operation is performed that involves at least one of the shift operation and the clutch operation on the clutch pedal and that is expected to cause the motor torque to be unable to satisfy the driver's requested torque, the engine is started,
The vehicle control device is characterized in that the predetermined operation is the clutch operation and an accelerator pedal operation of an amount equal to or greater than a predetermined threshold value performed simultaneously . The control unit
4. The vehicle control device according to claim 3, wherein even if the predetermined operation is performed during the EV mode, if the time during which the amount of accelerator operation is equal to or greater than the predetermined threshold is less than a predetermined time, the engine start is not initiated .