JP7530278B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device that controls a vehicle.

When fuel injection is performed while a vehicle driven by the rotational output of an internal combustion engine is coasting, if the charge state of the on-board battery is below a predetermined value, it is known that the on-board battery is charged by a generator (see, for example, Patent Document 1).

JP 2003-244998 A

From the perspective of improving fuel efficiency, it is preferable to rotate the generator at the rotational speed at which power generation efficiency is maximized (maximum efficient rotational speed). However, if the rotational speed of the internal combustion engine is controlled while the vehicle is coasting in order to rotate the generator at the maximum efficient rotational speed, changes in vehicle speed that differ from when the vehicle is coasting may occur, which may cause discomfort to the driver.

In view of the above problems, the present invention aims to provide a vehicle control device that controls the engine speed to rotate the generator at the most efficient rotation speed while the vehicle is coasting, while suppressing changes in vehicle speed that differ from when the vehicle is coasting.

For this reason, in the vehicle control device of the present invention, when a vehicle equipped with an internal combustion engine, a generator driven by the rotational output of the internal combustion engine, a transmission that transmits the rotational output of the internal combustion engine to drive wheels, and a battery charged by the generator is coasting, and when predetermined conditions are met including the battery's state of charge being less than a predetermined value, the forward clutch of the transmission is placed in a semi-engaged state in which a rotational speed difference occurs between the engagement elements of the forward clutch , while the engine rotational speed is controlled so that the generator's power generation efficiency is maximized, and while the engine rotational speed is controlled so that the generator's power generation efficiency is maximized, the engagement pressure of the forward clutch is controlled so that the vehicle speed changes at a predetermined acceleration corresponding to the gradient of the road surface on which the vehicle is traveling, and the predetermined acceleration is the acceleration expected when the vehicle is coasting in an engaged state in which no rotational speed difference occurs between the engagement elements of the forward clutch, and is determined in advance for each gradient of the road surface .

The vehicle control device of the present invention can control the engine speed to rotate the generator at the most efficient rotation speed while the vehicle is coasting, while suppressing changes in vehicle speed that differ from when the vehicle is coasting.

FIG. 1 is a schematic diagram illustrating an example of a drive system of a vehicle. 4 is a flowchart showing an example of a main routine related to power generation vehicle control. 5 is a flowchart showing an example of a generator vehicle control permission determination routine. 4 is a flowchart showing an example of a power generation vehicle control routine. FIG. 4 is an explanatory diagram showing the temperature characteristics of a generator. 5 is a flowchart showing an example of a generator vehicle control release routine. 4 is a time chart showing an example of an internal operation of a vehicle when a fuel cut occurs. 4 is a time chart showing an example of an internal operation of a vehicle when there is no fuel cut.

Below, an embodiment for implementing the present invention will be described in detail with reference to the attached drawings.

Figure 1 shows an example of a drive system of a vehicle to which a vehicle control device is applied. The drive source of the vehicle 1 is an internal combustion engine 10. The internal combustion engine 10 is, for example, a four-stroke engine, and includes an intake valve 11 that opens and closes an intake port, an exhaust valve 12 that opens and closes an exhaust port, a fuel injector 13 that injects fuel, an ignition device 14 that generates spark discharge, and an electronically controlled throttle valve 15 that adjusts the amount of intake air.

An air-fuel mixture formed in the combustion chamber is made by mixing the intake air that has passed through the throttle valve 15 with the fuel injected from the fuel injector 13, and this mixture is compressed when the piston 16 rises with both the intake valve 11 and the exhaust valve 12 closed. The compressed mixture is then ignited by a spark discharge from the ignition device 14, and the piston 16 is lowered by the combustion pressure of the mixture, causing a rotational motion in the crankshaft 18 connected to the piston 16 via a connecting rod 17. The rotational motion extracted from the crankshaft 18 is transmitted to the drive wheels 40 via the torque converter 20 and the transmission 30 as the driving force for the vehicle 1.

The transmission 30 has a forward clutch 31 and a CVT (Continuously Variable Transmission) 32. The forward clutch 31 is connected to the torque converter 20 via a transmission input shaft 33, etc., and the CVT 32 is connected to the forward clutch 31 via an intermediate shaft 34 and a planetary gear mechanism (not shown), and is connected to the drive wheels 40 via a transmission output shaft 35, etc.

The forward clutch 31 is engaged when the vehicle 1 is driven forward, and has a drive plate 31A on the driving side connected to the transmission input shaft 33, and a driven plate 31B on the driven side connected to the CVT 32 via an intermediate shaft 34 or the like. The drive plate 31A and the driven plate 31B are friction engagement elements, and when the forward clutch 31 is engaged, the drive plate 31A and the driven plate 31B engage with each other. The engagement and release of the drive plate 31A and the driven plate 31B is performed by hydraulic control of the hydraulic oil supplied to a clutch drive actuator (not shown), such as a piston.

The CVT 32 is a continuously variable transmission mechanism including a primary pulley 32A and a secondary pulley 32B, each of which is configured by a pair of movable cones arranged facing each other in the direction of contraction, and a belt 32C wound around these pulleys 32A and 32B. The rotation of the primary pulley 32A is transmitted to the secondary pulley 32B via the belt 32C, and the rotation of the secondary pulley 32B is transmitted to the drive wheels 40 via the transmission output shaft 35 or the like. When the pair of movable cones of the primary pulley 32A and the secondary pulley 32B are moved in the axial direction by hydraulic control of the hydraulic oil supplied thereto, the radius of the position where the primary pulley 32A and the secondary pulley 32B contact the belt 32C changes. This changes the pulley ratio (rotation ratio) between the primary pulley 32A and the secondary pulley 32B, and the gear ratio is adjusted continuously.

The internal combustion engine 10 is equipped with a generator (alternator) 60 that uses the rotational motion induced in the crankshaft 18 as a driving force to generate electricity, thereby supplying DC power to the vehicle's electrical equipment (not shown) and charging the vehicle's battery 50. The generator 60 is equipped with an AC generator that uses an electromagnet as a field magnet and a rectifier circuit that rectifies the AC output, and the generated voltage changes according to the field current.

The internal combustion engine 10 is controlled by an internal combustion engine control unit (hereinafter referred to as "ECU") 100, the generator 60 is controlled by a generator control unit (hereinafter referred to as "ACU") 200, and the transmission 30 is controlled by a transmission control unit (hereinafter referred to as "TCU") 300. The ECU 100, ACU 200, and TCU 300 each have a built-in microcomputer, and communicate with each other via a communication network 400 such as a CAN (Controller Area Network).

The ECU 100 receives output signals from an accelerator sensor (not shown), an accelerator switch 71, a crankshaft sensor 72, and a throttle opening sensor 73. The accelerator sensor outputs a signal that changes according to the amount of depression of the accelerator pedal 81. The accelerator switch 71 outputs a signal that changes according to whether the accelerator pedal 81 is depressed. The crankshaft sensor 72 outputs a signal that changes according to the speed of the rotational motion taken from the crankshaft 18 (hereinafter referred to as the "engine speed"). The throttle opening sensor 73 outputs a signal that changes according to the opening of the throttle valve 15. Based on the output signals from the above sensors and switches, the ECU 100 obtains the measured values of the amount of depression of the accelerator pedal 81, the engine speed, and the opening of the throttle valve 15, as well as information indicating whether the accelerator pedal 81 is depressed. The ECU 100 then controls the fuel injection device 13, the ignition device 14, and the throttle valve 15 based on the measured values and information.

The ECU 100 sets a target opening of the throttle valve 15 based on the measured value of the depression amount of the accelerator pedal 81, and controls the drive motor of the throttle valve 15 so that the measured value of the opening of the throttle valve 15 becomes the target opening. The ECU 100 calculates the fuel injection amount based on the intake air amount and the theoretical air-fuel ratio, and determines an appropriate ignition timing according to the measured value N of the engine rotation speed. The intake air amount can be obtained by various methods, for example, it can be actually measured by an intake amount sensor, or it can be estimated from the measured value of the opening of the throttle valve 15 and the measured value N of the engine rotation speed. The ECU 100 then outputs an injection pulse signal reflecting the calculated fuel injection amount to the fuel injection device 13, and outputs an ignition signal reflecting the determined ignition timing to the ignition device 14.

The ECU 100 also monitors whether the accelerator pedal 81 has changed from a depressed state (hereinafter referred to as "accelerator on") to a depressing state (hereinafter referred to as "accelerator off") and the vehicle 1 is coasting, based on the output signal of the accelerator switch 71. When the ECU 100 determines that the vehicle 1 is coasting, if a start condition is met, such as the engine speed being equal to or greater than a predetermined value, the ECU 100 sets the fuel cut permission flag to an on state and performs fuel cut control to stop fuel injection from the fuel injection device 13 to improve fuel efficiency. Then, if a release condition is met, such as the engine speed being less than a predetermined value, the fuel cut control is terminated and fuel injection is resumed.

The ACU 200 controls the field current of the generator 60 so that the generated voltage of the generator 60 is a predetermined voltage suitable as a power supply voltage for the on-board electrical equipment, even if the engine speed changes depending on the operating state of the vehicle 1. When the ECU 100 performs fuel cut control, the ACU 200 may increase the field current in response to a command signal from the ECU 100 to increase the generated voltage of the generator 60 above normal levels, thereby improving fuel efficiency.

The ACU 200 also estimates the state of charge (SOC) of the vehicle battery 50 to check whether the vehicle battery 50 needs to be charged by the generator 60. For example, the ACU 200 inputs an output signal from a current sensor 74 that outputs a signal that changes according to the charge/discharge current of the vehicle battery 50, obtains and integrates the measured value of the charge/discharge current based on this output signal, and estimates the SOC of the vehicle battery 50 based on the integrated value. The ACU 200 also inputs an output signal from a battery temperature sensor 75 that outputs a signal that changes according to the temperature inside the vehicle battery 50 (battery temperature), and obtains a measured value T of the battery temperature based on this output signal.

The TCU 300 controls the engagement and release of the forward clutch 31 via a clutch drive actuator (not shown) in response to the driver's operation input signal and the driving state of the vehicle 1 received from the ECU 100, and controls the gear ratio of the CVT 32. In order to diagnose the oil temperature in the transmission 30, the TCU 300 also inputs an output signal from an oil temperature sensor 76 that outputs a signal that changes depending on the oil temperature in the transmission 30, and acquires a measurement value of the oil temperature in the transmission 30.

Incidentally, when fuel injection is resumed during coasting of the vehicle 1, in the case of performing idle control to bring the engine speed closer to the idle speed Ni, it is assumed that the engine speed will be lower than the speed (hereinafter referred to as the "target engine speed") Nt required to rotate the generator 60 at the most efficient rotation speed Nmax. Here, the most efficient rotation speed Nmax is the speed at which the power generation efficiency of the generator 60 is highest when the generator 60 generates power to generate a predetermined power generation voltage. In response to the above assumption, it is conceivable to perform control to increase the engine speed to the target engine speed Nt and maintain it so that the generator 60 rotates at the most efficient rotation speed Nmax from the viewpoint of improving fuel efficiency. However, if control to increase and maintain the engine speed is performed during coasting of the vehicle 1, a vehicle speed change different from that during coasting of the vehicle occurs, which may cause the driver to feel uncomfortable. Therefore, the ECU 100 cooperates with the ACU 200 and the TCU 300 under a predetermined condition to perform power generation vehicle control in which the forward clutch 31 is in a semi-engaged state and the generator 60 rotates at the maximum efficient rotation speed Nmax after fuel injection is resumed and before idle control is started while the vehicle 1 is coasting. Here, the semi-engaged state of the forward clutch 31 refers to a state in which the drive plate 31A and the driven plate 31B are continuously or intermittently engaged (contacted) and rotate at different speeds. The ECU 100, the ACU 200, and the TCU 300 constitute a vehicle control device that performs power generation vehicle control and related processing (hereinafter referred to as "processing related to power generation vehicle control").

The ECU 100 performs processing related to the power generation vehicle control through software processing in which a processor in an internal microcomputer reads a program stored in a non-volatile memory into a volatile memory and executes the program. However, this does not exclude the possibility that part or all of the processing related to the power generation vehicle control is realized by a hardware configuration.

In order to perform processing related to the power generation vehicle control, the ECU 100 inputs output signals from the accelerator switch 71, crankshaft sensor 72, throttle opening sensor 73, vehicle speed sensor 77, and brake switch 78. The vehicle speed sensor 77 outputs a signal that changes according to the vehicle speed, and the brake switch 78 outputs a signal that changes according to whether the brake pedal 82 is depressed. The ECU 100 obtains a measurement value V of the vehicle speed based on the output signal of the vehicle speed sensor 77, and obtains information indicating whether the brake pedal 82 is depressed based on the output signal of the brake switch 78. The ECU 100 then performs processing related to the power generation vehicle control based on the measurement values of the engine speed, the opening of the throttle valve 15, and the vehicle speed, and information indicating whether the accelerator pedal 81 and the brake pedal 82 are depressed.

In addition, the TCU 300 performs control to put the forward clutch 31 into a semi-engaged state (hereinafter referred to as "semi-engaged control") by receiving a command signal from the ECU 100. To perform the semi-engaged control, the TCU 300 inputs output signals from two sensors, the first rotational speed sensor 79A and the second rotational speed sensor 79B. The first rotational speed sensor 79A outputs a signal that changes according to the rotational speed of the drive plate 31A (hereinafter referred to as "first rotational speed"). The second rotational speed sensor 79B outputs a signal that changes according to the rotational speed of the driven plate 31B (hereinafter referred to as "second rotational speed"). The TCU 300 obtains a measurement value N1 of the first rotational speed based on the output signal of the first rotational speed sensor 79A, and obtains a measurement value N2 of the second rotational speed based on the output signal of the second rotational speed sensor 79B. The TCU 300 performs the semi-engaged control based on the measurement value N1 of the first rotational speed and the measurement value N2 of the second rotational speed.

Figure 2 shows an example of a main routine for processing related to power generation vehicle control that is repeatedly executed in ECU 100 when power supply to ECU 100 is started. Note that the processing related to power generation vehicle control is described as being executed in parallel with other control processing in ECU 100, but this does not exclude the processing being executed as part of the other control processing. In addition, when processing related to power generation vehicle control is started, the power generation vehicle control permission flag and power generation vehicle control execution flag described below are initialized to the off state.

In step 101 (hereinafter, step is abbreviated as "S"), the ECU 100 determines whether or not to permit power generation vehicle control. If the ECU 100 determines in S101 that power generation vehicle control is permitted, the ECU 100 sets the power generation vehicle control permission flag to the ON state, and if the ECU 100 determines that power generation vehicle control is prohibited, the ECU 100 sets the power generation vehicle control permission flag to the OFF state. Details of the determination of whether or not to permit power generation vehicle control will be described later.

In S102, if the power generation vehicle control is permitted (YES), the ECU 100 advances the process to S103, whereas if the power generation vehicle control is not permitted (NO), the ECU 100 advances the process to S104. The ECU 100 can determine whether the power generation vehicle control is permitted based on the power generation vehicle control permission flag.

In S103, the ECU 100 performs power generation vehicle control. The ECU 100 sets a power generation vehicle control execution flag, which indicates that power generation vehicle control has been executed in S103, to an ON state, returns the process to S101, and checks whether power generation vehicle control is permitted. In short, the ECU 100 continues to perform power generation vehicle control as long as power generation vehicle control is permitted. Details of power generation vehicle control will be described later.

In S104, if the ECU 100 is controlling the power generation vehicle (YES), the process proceeds to S105. If the ECU 100 is not controlling the power generation vehicle (NO), the process skips S105, temporarily ends the process related to the power generation vehicle control, and restarts from S101. The ECU 100 can determine whether the power generation vehicle control is in progress based on the state of the power generation vehicle control execution flag.

In S105, the ECU 100 cancels the power generation vehicle control executed in S103. Details of the cancellation of power generation vehicle control will be described later.

Figure 3 shows an example of a power generation vehicle control permission determination routine that is called in S101 of the process related to power generation vehicle control (see Figure 2).

In S201, the ECU 100 determines whether the SOC of the vehicle battery 50 is less than a lower limit. This lower limit is a value set based on the minimum state of charge required for starting and running the vehicle 1. The ECU 100 can obtain the SOC of the vehicle battery 50 from the ACU 200 via the communication network 400. If the ECU 100 determines that the SOC of the vehicle battery 50 is less than the lower limit (YES), it determines that there is a need for power generation vehicle control to perform rapid battery charging, and proceeds to S202. On the other hand, if the ECU 100 determines that the SOC of the vehicle battery 50 is equal to or greater than a predetermined value (NO), it determines that rapid battery charging is not required, and therefore there is no need for power generation vehicle control, and proceeds to S208.

In S202, the ECU 100 determines whether the rotational speed sensors 79A and 79B used in the power generation vehicle control are normal. Whether the first rotational speed sensor 79A is normal can be determined based on a comparison between the measured value N1 of the first rotational speed and the measured value N of the mechanical rotational speed. Whether the second rotational speed sensor 79B is normal can be determined based on a comparison between the measured value N2 of the second rotational speed and the measured value V of the vehicle speed. If the ECU 100 determines that the rotational speed sensors 79A and 79B are normal (YES), it determines that power generation vehicle control is possible and proceeds to S203. On the other hand, if the ECU 100 determines that the rotational speed sensors 79A and 79B are abnormal (NO), it determines that power generation vehicle control is impossible and proceeds to S208.

In S203, the ECU 100 determines whether the accelerator is off based on the output signal of the accelerator switch 71. If the ECU 100 determines that the accelerator is off (YES), it determines that the vehicle 1 is possibly coasting, and proceeds to S204. On the other hand, if the ECU 100 determines that the accelerator is on (NO), it determines that the vehicle 1 is not coasting, and proceeds to S208.

In S204, if the fuel cut permission flag is off (YES), the ECU 100 determines that fuel injection is possible and therefore the engine speed can be controlled as part of the power generation vehicle control, and proceeds to S205. On the other hand, if the fuel cut permission flag is on (NO), the ECU 100 determines that fuel injection is prohibited and therefore the engine speed cannot be controlled as part of the power generation vehicle control, and proceeds to S208.

In S205, the ECU 100 determines whether the vehicle 1 is traveling based on the output signal of the vehicle speed sensor 77. Whether the vehicle 1 is traveling can be determined by determining whether the measured vehicle speed V obtained based on the output signal of the vehicle speed sensor 77 is higher than 0 km/h or a value close to 0 km/h. If the ECU 100 determines that the vehicle 1 is traveling (YES), the ECU 100 determines that the vehicle 1 is coasting and therefore the kinetic energy of the vehicle 1 can be used to generate electricity by the generator 60, and proceeds to S206. On the other hand, if the ECU 100 determines that the vehicle 1 is not traveling, i.e., is stopped (NO), the ECU 100 determines that the kinetic energy of the vehicle 1 is not being generated to be used to generate electricity by the generator 60, and proceeds to S208.

In S206, the ECU 100 determines whether the measured value of the oil temperature in the transmission 30 is below a threshold value based on the output signal of the oil temperature sensor 76. This threshold value is the lower limit of the oil temperature at which the drive plate 31A and the driven plate 31B slip relative to each other and the forward clutch 31 cannot be in a semi-engaged state. If the ECU 100 determines that the measured value of the oil temperature in the transmission 30 is below the threshold value (YES), it determines that the forward clutch 31 can be in a semi-engaged state and proceeds to S207. On the other hand, if the ECU 100 determines that the measured value of the oil temperature in the transmission 30 is equal to or higher than the threshold value (NO), it determines that the forward clutch 31 cannot be in a semi-engaged state and proceeds to S208.

In S207, the ECU 100 permits the power generation vehicle control, whereas in S208, the ECU 100 prohibits the power generation vehicle control. After executing S207 or S208, the ECU 100 exits the power generation vehicle control permission determination routine and advances to S102 of the main routine, which is the processing related to the power generation vehicle control (see FIG. 2).

Figure 4 shows an example of a power generation vehicle control routine that is called in S103 of the main routine, which is the processing related to power generation vehicle control (see Figure 2).

In S301, the ECU 100 transmits a command signal to the TCU 300 to perform half-engagement control. The TCU 300, which receives the command signal, performs half-engagement control by hydraulic control of the hydraulic oil supplied to a clutch drive actuator (not shown) of the forward clutch (referred to as "F clutch" in the figure; the same applies below). The specific content of the half-engagement control will be described later.

In S302, the ECU 100 determines whether the forward clutch 31 is in a semi-engaged state. The ECU 100 executes S302 in response to the result of the TCU 300's determination of whether the forward clutch 31 is in a semi-engaged state based on the two measured values N1, N2 of the first rotation speed and the second rotation speed, or may execute S302 based on the two measured values N1, N2 of the first rotation speed and the second rotation speed received from the TCU 300.

Incidentally, when the vehicle 1 is coasting with fuel injection stopped, in the engaged state of the forward clutch 31, at least the first rotation speed and the second rotation speed are approximately equal to each other. However, when the forward clutch 31 transitions from the engaged state to the semi-engaged state, a speed difference occurs between the first rotation speed and the second rotation speed, and when it transitions further to the released state, the speed difference becomes larger than when it is in the semi-engaged state. Therefore, whether the forward clutch 31 is in the semi-engaged state can be determined based on the difference between the two measured values N1 and N2 of the first rotation speed and the second rotation speed. In addition, the ECU 100 or the TCU 300 may execute S302 after a predetermined time has elapsed from S21, taking into account the operation time of the forward clutch 31 and the rotational inertia of the crankshaft 18. In addition, the ECU 100 or the TCU 300 may temporarily increase the engine rotation speed. This is because if the forward clutch 31 is in a released state, the second rotation speed does not increase even if the engine rotation speed increases, so it is possible to clearly determine whether the forward clutch 31 is in a partially engaged state or a released state.

If the ECU 100 determines in S302 that the forward clutch 31 is in a semi-engaged state (YES), the process proceeds to S303. On the other hand, if the ECU 100 determines that the forward clutch 31 is not in a semi-engaged state (NO), the ECU 100 determines that it is not possible to implement power generation vehicle control, and returns to and ends the process related to power generation vehicle control (see FIG. 2).

In S303, the ECU 100 determines whether the measured value T of the battery temperature is less than a predetermined threshold value Tth. The ECU 100 acquires the measured value T of the battery temperature acquired by the ACU 200 based on the output signal of the battery temperature sensor 75 by receiving it as communication information via the communication network 400. If the ECU 100 determines that the measured value T of the battery temperature is less than the threshold value Tth (YES), the process proceeds to S304. On the other hand, if the ECU 100 determines that the measured value T of the battery temperature is equal to or greater than the threshold value Tth (NO), the process proceeds to S305.

In S304, the ECU 100 sets the target engine speed Nt to a speed _NA when the measured value T of the battery temperature is less than the threshold value Tth. On the other hand, in S305, the ECU 100 sets the target engine speed Nt to a speed _{NB higher than the speed NA when} the measured value T of the battery temperature is equal to or greater than the threshold value Tth.

Here, the reason why the target engine rotation speed Nt is changed according to the battery temperature will be described with reference to FIG. 5. FIG. 5 shows the relationship between the rotation speed and the power generation amount of the generator 60 when the generator 60 is cold and when the generator 60 is warmed up. In FIG. 5, when comparing the rotation speeds required to generate the same power generation amount Q [A] by the generator 60 when cold and the generator 60 when warmed up, the rotation speed _NH of the generator 60 when warmed up is higher than the rotation speed _NL of the generator 60 when cold. Therefore, as the ambient temperature of the generator 60 increases, the maximum efficiency rotation speed Nmax of the generator 60 also increases. The ambient temperature of the generator 60 can be indirectly grasped by the battery temperature, and the engine rotation speed required to rotate the generator 60 at the maximum efficiency rotation speed Nmax as described above is the target engine rotation speed Nt. For this reason, the target engine rotation speed Nt is changed according to the battery temperature.

Although the battery temperature is used as the ambient temperature of the generator 60, it is of course also possible to use a temperature parameter that indirectly indicates the temperature of the generator 60 itself or the ambient temperature of the generator 60.

In S306, the ECU 100 performs feedback control so that the measured engine speed N obtained based on the output signal of the crankshaft sensor 72 becomes the target engine speed Nt set in S304 or S305.

For example, in S306, the ECU 100 calculates the amount of operation of the drive motor (not shown) of the throttle valve 15 based on the deviation between the target engine speed Nt and the measured engine speed N, and outputs a control signal reflecting this amount of operation to the drive motor. Feedback control such as PI control or PID control can be used to calculate the amount of operation of the drive motor of the throttle valve 15.

In S306, when the measured engine speed N is higher than the target engine speed Nt, the deviation becomes negative, and the amount of operation of the drive motor calculated by PI control or PID control becomes relatively small. As a result, the throttle valve 15 is fully closed or opens relatively small, so the engine speed decreases or its increase is suppressed. On the other hand, when the measured engine speed N falls below the target engine speed Nt, the deviation becomes positive, and the amount of operation becomes relatively large, increasing the opening of the throttle valve 15, and thus the measured engine speed N increases toward the target engine speed Nt.

After executing S306, the ECU 100 exits the power generation vehicle control routine and proceeds to S101 of the power generation vehicle control process (see FIG. 2).

Here, the mode of the semi-engaged control that the TCU 300 executes in response to the command signal from the ECU 100 in S301 will be described. The semi-engaged control is performed in a number of modes so that even if the engine speed is controlled during coasting of the vehicle 1 in S306, the occurrence of a change in vehicle speed that differs from that during coasting of the vehicle 1 is suppressed.

In the first mode of semi-engaged control, the TCU 300 performs hydraulic control of the clutch drive actuator so that the engagement pressure between the drive plate 31A and the driven plate 31B becomes a predetermined pressure. The predetermined pressure is, for example, the minimum engagement pressure that can be generated by the clutch drive actuator. Specifically, the TCU 300 performs hydraulic control of the clutch drive actuator so that the difference between the two measured values N1, N2 of the first rotation speed and the second rotation speed becomes a predetermined value corresponding to the above-mentioned predetermined pressure.

As a second mode of the half-engagement control, when the vehicle 1 is decelerating by coasting, the TCU 300 performs hydraulic control of the clutch drive actuator so that the measured value V of the vehicle speed decreases according to a predetermined deceleration a. The predetermined deceleration a is the deceleration that occurs when the vehicle 1 decelerates by coasting, and is determined in advance by experiments, simulations, etc., and stored in the ROM (Read Only Memory) of the ECU 100. For example, the TCU 300 performs hydraulic control of the clutch drive actuator so that the measured value N2 of the second rotation speed becomes the ideal second rotation speed obtained by converting the current ideal vehicle speed obtained from the predetermined deceleration a by the set gear ratio of the CVT 32, etc. The ECU 100 may obtain the gradient of the road surface from a gradient acquisition means (e.g., an acceleration sensor) that measures or estimates the gradient of the road surface on which the vehicle 1 is traveling, and change the predetermined deceleration a according to the gradient of the road surface.

As a third mode of the semi-engaged control, when the vehicle 1 is decelerating by coasting, the TCU 300 performs hydraulic control of the clutch drive actuator so that the engagement pressure between the drive plate 31A and the driven plate 31B decreases as the SOC of the vehicle battery 50 increases. The TCU 300 obtains the SOC value of the vehicle battery 50 from the ACU 200 via the communication network 400.

The first to third modes of the half-engagement control may be used in combination. For example, when the vehicle 1 is decelerating, the half-engagement control may be performed according to the second or third mode in principle, and when the measured value N of the engine rotation speed is increasing, the half-engagement control may be performed with the minimum engagement pressure according to the first mode. Also, the mode of the half-engagement control may be different before and after determining in S302 whether the forward clutch 31 is in a half-engaged state.

Figure 6 shows an example of a power generation vehicle control release routine that is called in S105 of the power generation vehicle control process (see Figure 2).

In S401, the ECU 100 determines whether the brake pedal 82 is depressed (hereinafter referred to as "brake on") based on the output signal of the brake switch 78. If the ECU 100 determines that the brake is on (YES), it determines that there is no possibility of acceleration operation and proceeds to S403. On the other hand, if the ECU 100 determines that the brake is not on, that is, that the brake pedal 82 is not depressed (hereinafter referred to as "brake off") (NO), it proceeds to S402.

In S402, the ECU 100 determines whether the accelerator is off based on the output signal of the accelerator switch 71. If the ECU 100 determines that the accelerator is off (YES), it determines that no acceleration operation is being performed but that there is a possibility of an acceleration operation, and proceeds to S404. On the other hand, if the ECU 100 determines that the accelerator is on (NO), it determines that an acceleration operation has been performed, and proceeds to S405.

The ECU 100 executes S403 when there is no possibility of an acceleration operation, executes S404 when an acceleration operation is not performed but there is a possibility of an acceleration operation, and executes S405 when an acceleration operation is performed, and sets the engagement speed of the forward clutch 31 according to the possibility of an acceleration operation. If the engagement speed set in S403 is _UA , the engagement speed set in S404 is _UB , and the engagement speed set in S405 is _UC , the magnitude relationship among the engagement speeds _UA , _UB , and _UC is _UA < _UB < _UC so that the forward clutch 31 is engaged more quickly as the possibility of an acceleration operation increases.

In S406, the ECU 100 performs idle control to bring the measured engine speed N closer to the idle speed Ni.

In S407, the ECU 100 determines whether the measured engine speed N has converged to the idle speed Ni based on the output signal of the crankshaft sensor 72. If the ECU 100 determines that the measured engine speed N has converged to the idle speed Ni (YES), the ECU 100 advances the process to S408, whereas if the ECU 100 determines that the measured engine speed N still deviates from the idle speed Ni (NO), the ECU 100 returns the process to S401.

In S408, the ECU 100 transmits a command signal to the TCU 300 to control the forward clutch 31 to be in an engaged state (engagement control). The TCU 300, which receives the command signal, performs engagement control by hydraulic control of the hydraulic oil supplied to the clutch drive actuator.

In S409, the ECU 100 determines whether the forward clutch 31 is engaged. Whether the forward clutch 31 is engaged can be determined by whether the two measured values N1, N2 of the first rotation speed and the second rotation speed are approximately equal to each other. If the ECU 100 determines that the forward clutch 31 is engaged (YES), the ECU 100 exits the power generation vehicle control release routine and ends the processing related to the power generation vehicle control (see FIG. 2). On the other hand, if the ECU 100 determines that the forward clutch 31 is not engaged (NO), the ECU 100 returns the processing to S408 and sends a command signal to the TCU 300 to perform engagement control again.

The ECU 100 may perform engagement control (S408) when at least one of the following conditions is met: the measured engine speed N converges to the idle speed Ni; and the two measured first and second engine speeds N1, N2 are approximately equal to each other. This type of control is particularly effective in that when the ECU 100 determines in S402 that the accelerator is on, the execution of S406 and S407 may reduce a delay in response to an acceleration operation.

Figure 7 shows an example of the internal operation of vehicle 1 through fuel cut control and subsequent processing related to vehicle control for power generation.

When the accelerator changes from on to off at time t1 and the vehicle 1 starts coasting, if the conditions for starting the fuel cut control are met, the ECU 100 sets the fuel cut permission flag, which indicates the stop of fuel injection, to the on state and starts the fuel cut control. Even during the fuel cut control, the SOC of the on-board battery 50 increases due to the power generation of the generator 60, but as shown in Figure 7, the SOC of the on-board battery 50 has not yet reached the lower limit.

At time t2, when the release condition for the fuel cut control is satisfied, the ECU 100 sets the fuel cut permission flag to the OFF state, and the fuel cut control ends. At this time, as shown in FIG. 7, the SOC of the vehicle battery 50 is below the lower limit, and the vehicle 1 is running. Therefore, if the oil temperature in the transmission 30 is below the threshold value, and the rotational speed sensors 79A and 79B are normal, the ECU 100 sets the power generation vehicle control permission flag, which indicates permission for power generation vehicle control, to the ON state. Then, as the power generation vehicle control, the ECU 100 first causes the TCU 300 to perform half-engagement control of the forward clutch 31. This half-engagement control generates a speed difference between the first rotational speed (solid line) and the second rotational speed (dashed line).

At time t3, when the ECU 100 determines that the forward clutch 31 is in a semi-engaged state, it starts controlling the engine speed so that the current engine speed becomes the target engine speed Nt required to rotate the generator 60 at the most efficient rotation speed Nmax.

At time t4, when the SOC of the vehicle battery 50 becomes equal to or higher than the lower limit, the ECU 100 changes the power generation vehicle control permission flag from ON to OFF to prohibit power generation vehicle control. As a result, the ECU 100 ends the control for matching the engine speed to the target engine speed Nt, and starts idle control.

Between times t3 and t4, the engine speed increases to and is maintained at the target engine speed Nt, so the SOC of the vehicle battery 50 increases at a greater rate than during fuel cut control (between times t1 and t2).

In addition, from time t3 to t4, the engine speed increases to the target engine speed Nt and is maintained there, so the first rotation speed increases, but the increase in the second rotation speed is suppressed because the half-engagement control is being performed. If the half-engagement control were not performed from time t3 to t4, the engine speed would increase to the target engine speed Nt and be maintained there, so the second rotation speed would increase in the same way as the first rotation speed. Since the second rotation speed is reflected in the vehicle speed and the first rotation speed reflects the engine speed, the vehicle speed when the half-engagement control is performed is lower than when the half-engagement control is not performed. In other words, the vehicle speed when the half-engagement control is performed in the power generation vehicle control (solid line) changes to a value closer to the vehicle speed when the vehicle 1 is coasting without the power generation vehicle control (dashed line) compared to the vehicle speed when the half-engagement control is not performed (dash line).

At time t5, when the engine speed converges to the idle speed Ni, the ECU 100 causes the TCU 300 to perform engagement control, changing the forward clutch 31 from a semi-engaged state to an engaged state.

However, it is assumed that fuel cut control will be omitted even when vehicle 1 transitions to coasting due to the specifications of vehicle 1 or because the conditions for starting fuel cut control are not met. The internal operation of vehicle 1 when processing related to power generation vehicle control is performed in such a case where fuel cut control is omitted will be described with reference to FIG. 8.

Figure 8 shows an example of the internal operation of the vehicle 1 by the process related to the power generation vehicle control when the fuel cut control is omitted. As is clear from Figure 8, when the vehicle 1 starts coasting by changing from accelerator on to accelerator off at time t1, the fuel cut control is omitted and the operation proceeds to the operation at time t2 in Figure 7. That is, as shown in Figure 8, since the SOC of the vehicle battery 50 is less than the lower limit value and the vehicle 1 is running, if the oil temperature of the transmission 30 is less than the threshold value and the rotation speed sensors 79A and 79B are normal, the ECU 100 sets the power generation vehicle control permission flag, which indicates permission for power generation vehicle control, to an ON state. Then, the ECU 100 first causes the TCU 300 to perform half-engagement control of the forward clutch 31 as the power generation vehicle control. This half-engagement control generates a speed difference between the first rotation speed (solid line) and the second rotation speed (dashed line).

At time t2, when the ECU 100 determines that the forward clutch 31 is in a semi-engaged state, it starts controlling the engine speed so that the current engine speed becomes the target engine speed Nt required to rotate the generator 60 at the most efficient rotation speed Nmax.

At time t3, when the SOC of the vehicle battery 50 becomes equal to or higher than the lower limit, the ECU 100 changes the power generation vehicle control permission flag from ON to OFF to prohibit power generation vehicle control. As a result, the ECU 100 ends the control for matching the engine speed to the target engine speed Nt, and starts idle control.

Between time t2 and t3, the engine speed increases to and is maintained at the target engine speed Nt, so the SOC of the vehicle battery 50 increases at a greater rate than before time t2.

In addition, from time t2 to t3, the first rotation speed increases as the engine speed increases and is maintained at the target engine rotation speed Nt, but the increase in the second rotation speed is suppressed because half-engagement control is being performed. As in FIG. 7, the vehicle speed when half-engagement control is performed in the power generation vehicle control (solid line) changes to a value closer to the vehicle speed when the vehicle 1 is coasting without power generation vehicle control (dashed line) compared to the vehicle speed when half-engagement control is not performed (dashed line). Note that the subsequent operations are the same as in FIG. 7, so a description thereof will be omitted.

According to such a vehicle control device, when a predetermined condition is met while the vehicle 1 is coasting, regardless of whether or not fuel cut control is performed, power generation vehicle control is performed in which the forward clutch 31 is in a half-engaged state and the generator 60 is rotated at the most efficient rotation speed Nmax. As a result, the vehicle speed when half-engaged control is performed in the power generation vehicle control changes to a value closer to the vehicle speed when the vehicle 1 is coasting without the power generation vehicle control, compared to the vehicle speed when half-engaged control is not performed. Therefore, while the vehicle 1 is coasting, it is possible to suppress vehicle speed changes that differ from when the vehicle is coasting, while rotating the generator 60 at the most efficient rotation speed Nmax by controlling the engine rotation speed.

In addition, in the generator vehicle control permission determination routine of FIG. 3, a process may be added to determine that generator vehicle control is permitted when the measured engine speed N is less than the target engine speed Nt, and to prohibit generator vehicle control when the measured engine speed N is equal to or greater than the target engine speed Nt. If generator vehicle control is prohibited by this process, the throttle valve 15 is held in a fully closed state, so that the engine speed is reduced to the target engine speed Nt or the increase in engine speed can be suppressed. When determining whether or not generator vehicle control is required depending on the target engine speed Nt, the generator vehicle control permission determination routine incorporates the processes of S303 to S305 of FIG. 4. If the current engine speed is less than the target engine speed Nt, generator vehicle control can be started, so that the current engine speed can be increased to the target engine speed Nt by S306.

In S304 and S305 of FIG. 5, the target engine speed Nt is set in two stages, one for when the battery temperature is relatively high and one for when the battery temperature is relatively low. Alternatively, the target engine speed Nt may be set in three or more stages depending on the battery temperature.

In the above embodiment, the ECU 100 controls the internal combustion engine 10, and the ACU 200 controls the generator 60. However, the ACU 200 may be omitted and the ECU 100 may control the generator 60.

Although the processing related to the power generation vehicle control has been described as being performed in the ECU 100, such processing may be performed in any of the ECU 100, the ACU 200, and the TCU 300. In addition, processing related to the power generation vehicle control may be performed in a control device other than the ECU 100, the ACU 200, and the TCU 300.

A control device that integrates at least two of the ECU 100, ACU 200, and TCU 300 may perform processing related to power generation vehicle control. For example, the ECU 100, which integrates the functions of the ACU 200, may perform processing related to power generation vehicle control.

Although a continuously variable transmission using a CVT 32 has been exemplified as the transmission 30 of the vehicle 1, any transmission equipped with a forward clutch 31, whether stepped or non-stepped, can be used as the transmission 30 of the vehicle 1.

The forward clutch 31 is configured as part of the transmission 30, but instead of the forward clutch 31, a power cut-off mechanism equivalent to the forward clutch 31 may be placed between the internal combustion engine 10 and the drive wheels 40.

Although a four-stroke engine has been exemplified as the internal combustion engine 10, a two-stroke engine may also be used. In addition, the output signals of various sensors required by the ECU 100 for processing related to the power generation vehicle control may be input directly without going through the ACU 200 or TCU 300.

The contents of the present invention have been specifically described above with reference to preferred embodiments, but the technical ideas described above can be used in appropriate combinations as long as no contradictions arise. Furthermore, it is self-evident that a person skilled in the art would be able to adopt various modified forms based on the basic technical ideas and teachings of the present invention.

1...vehicle, 10...internal combustion engine, 30...transmission, 31...forward clutch, 31A...drive plate, 31B...driven plate, 50...vehicle battery, 60...generator, N...measured engine speed, Nmax...maximum efficient speed, Nt...target engine speed, N1...measured first speed, N2...measured second speed, T...measured battery temperature, SOC...state of charge of vehicle battery

Claims (3)

a vehicle including an internal combustion engine, a generator driven by a rotational output of the internal combustion engine, a transmission that transmits the rotational output of the internal combustion engine to drive wheels, and a battery that is charged by the generator, when predetermined conditions are satisfied during coasting of the vehicle, including a state of charge of the battery falling below a predetermined value, a forward clutch of the transmission is brought into a semi-engaged state in which a rotational speed difference occurs between engagement elements of the forward clutch , while controlling the engine rotational speed so as to maximize the power generation efficiency of the generator ;
while controlling the engine rotation speed so as to maximize the power generation efficiency of the generator, controlling the engagement pressure of the forward clutch so that the vehicle speed changes at a predetermined acceleration corresponding to the gradient of the road surface on which the vehicle is traveling;
A vehicle control device, wherein the predetermined acceleration is an acceleration expected when the vehicle coasts in an engaged state in which no rotational speed difference occurs between the engagement elements of the forward clutch, and is determined in advance for each gradient of a road surface . The vehicle control device according to claim 1, which controls the internal combustion engine so that the measured engine speed becomes a target engine speed, which is the engine speed at which the power generation efficiency of the generator is maximized, and sets the target engine speed according to the ambient temperature of the generator. 3. The vehicle control device according to claim 1, wherein, when the forward clutch is brought into a half-engaged state, an engagement pressure of the forward clutch is reduced as a state of charge of the battery increases.