JP2007284001A - Vehicle and control method thereof - Google Patents

Abstract

In a vehicle having an electric motor capable of outputting a regenerative braking force to either one of front and rear wheels, the braking force applied to the front and rear wheels is balanced when the regenerative braking force by the electric motor is used.
In the hybrid vehicle 20, when the regenerative braking force by the motor 50 is used when the brake pedal 85 is depressed, the rotational speed control of the engine 22 (crankshaft 23) and the alternator control via the CVT 40 (step S210). Alternatively, the engine-induced braking force, which is a braking force based on S220), is output to the front wheels 65a and 65b, and the regenerative braking force by the motor 50 is output to the rear wheels 65c and 65d so that the required braking force BF * is obtained. 50, CVT 40, alternator 28, and brake actuator 102 of HBS 100 are controlled.
[Selection] Figure 2

Description

  The present invention relates to a vehicle and a control method thereof, and more particularly, to a vehicle including an electric motor capable of outputting at least a regenerative braking force to any one of front and rear wheels and a control method thereof.

Conventionally, a vehicle including an engine connected to one of the front and rear wheels via a first electric motor and a transmission capable of generating electricity, and a second electric motor capable of generating electricity connected to the other of the front and rear wheels (For example, refer to Patent Documents 1 and 2). In this type of vehicle, at the time of regenerative braking using two electric motors, the braking performance is controlled by controlling the distribution ratio of the regenerative braking force by the first and second motors to be an ideal distribution ratio according to the longitudinal acceleration. Can be increased. Further, conventionally, an ideal ideal front / rear wheel distribution ratio between the braking torque to the front wheels and the braking torque to the rear wheels is calculated, and a distribution tolerance for the ideal front / rear wheel distribution ratio is calculated. The ideal front and rear wheel distribution ratio is corrected so that the power generation efficiency of the first motor generator connected to the rear wheels and the second motor generator connected to the front wheels within the range is increased, and the obtained front and rear wheel distribution ratio is obtained. A method of calculating a torque command value for each motor generator based on the above is also known (see, for example, Patent Document 3).
JP 2004-166363 A JP 2002-213266 A JP 2004-1357471 A

  As described above, in a vehicle equipped with electric motors capable of generating electricity on each of the front and rear wheels, the two motors can be controlled so that the distribution ratio of the regenerative braking force to the front and rear wheels becomes the target distribution ratio. In a vehicle equipped with an electric motor only on one of the front and rear wheels, unless any countermeasure is taken, the balance of the braking force against the front and rear wheels is lost when the regenerative braking force by the electric motor is used, and at the time of braking The behavior may become unstable.

  Therefore, the vehicle and the control method thereof according to the present invention provide a balance between the braking force applied to the front and rear wheels when the regenerative braking force by the motor is used in a vehicle including an electric motor that can output the regenerative braking force to either one of the front and rear wheels. One of the purposes is to take. Another object of the vehicle and the control method thereof according to the present invention is to further stabilize the behavior during braking in a vehicle including an electric motor capable of outputting a regenerative braking force on either one of the front and rear wheels.

  The vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-described object.

The vehicle according to the present invention is
An internal combustion engine;
A shift capable of shifting the power of the input shaft connected to the engine shaft of the internal combustion engine with a change in the gear ratio and outputting it to the output shaft connected to the first wheel which is either the front wheel or the rear wheel. Means,
An electric motor capable of outputting at least a regenerative braking force to a second wheel which is the other of the front wheel and the rear wheel;
A generator coupled to the engine shaft of the internal combustion engine;
Power storage means capable of exchanging power with the generator and the motor;
Requested braking force setting means for setting a requested braking force requested by a braking request operation;
When the regenerative braking force by the electric motor is used when the braking request operation is performed, the engine is a braking force based on the rotational speed control of the engine shaft and the control of the generator via the transmission means. The motor, the speed change means, and the motor are configured so that a braking force is output to the first wheel and the regenerative braking force by the motor is output to the second wheel to obtain the set required braking force. Braking control means for controlling the generator;
Is provided.

  In this vehicle, when a regenerative braking force by an electric motor is used when a braking request operation is performed, an engine-induced braking force that is a braking force based on the engine speed control and the generator control via the transmission means is reduced. The motor, the transmission means, and the generator are controlled so that the regenerative braking force by the motor is output to the second wheel and the required braking force requested by the braking request operation is obtained while being output to the first wheel. The In this way, if the engine shaft speed control and the generator control are performed via the speed change means when the regenerative braking force by the electric motor is output to the second wheel, the braking force by the engine brake of the internal combustion engine Alternatively, an engine-induced braking force that is the sum of the braking force generated by the engine brake and the regenerative braking force generated by the generator is output to the first wheel to balance the braking force between the first wheel and the second wheel. As a result, the behavior of the vehicle during braking can be stabilized. In this vehicle, it is also possible to charge the power storage means using electric power obtained by controlling the generator in addition to regenerative electric power generated by the electric motor during braking. The “braking request operation” referred to here includes an operation (accelerator off operation) for releasing the depression of the accelerator pedal in addition to the depression operation of the brake pedal.

  In this case, the braking control means causes the ratio between the engine-induced braking force output to the first wheel and the regenerative braking force output to the second wheel to be a predetermined target front / rear distribution ratio. Further, the electric motor, the transmission means and the generator may be controllable. As a result, it is possible to improve the braking performance of the vehicle by more appropriately distributing the braking force to the first and second wheels. The target front / rear distribution ratio may be constant or may be changed according to the state of the vehicle.

  The vehicle of the present invention may further include a fluid pressure type braking unit capable of outputting a braking force to the first wheel and the second wheel, and the braking control unit includes the braking request operation. When the regenerative braking force by the electric motor and the fluid pressure braking force that is the braking force by the fluid pressure braking means are used, the engine-induced braking force, the regenerative braking force, and the fluid pressure braking force At least the electric motor, the transmission means, and the generator may be controlled so that the set required braking force is covered. As a result, the required braking force requested by the braking request operation can always be ensured satisfactorily.

  Further, the fluid pressure braking means may be capable of applying a braking force to the first wheel and the second wheel with a substantially constant front-rear distribution ratio, and the braking control means may be configured to perform the braking request operation. When the regenerative braking force and the fluid pressure braking force by the electric motor are used, the sum of the engine-induced braking force and the fluid pressure braking force output to the first wheel, Controlling at least the electric motor, the transmission means, and the generator so that a ratio of the regenerative braking force output to the wheel and the sum of the fluid pressure braking force is a predetermined target front-rear distribution ratio; Also good. In this way, if the braking force according to the target front / rear distribution ratio is distributed to the first wheel and the second wheel by adjusting the engine-induced braking force and the regenerative braking force by the electric motor, the fluid pressure braking is performed. A means having a relatively simple configuration can be adopted as a means.

  Further, the braking control means may set the regenerative braking force by the electric motor and the regenerative braking force by the generator according to the remaining capacity of the power storage means. Thereby, it is possible to suppress the overcharge of the power storage means and suppress the deterioration of the power storage means.

  Furthermore, the speed change means may be a continuously variable transmission capable of changing the speed ratio steplessly. This makes it possible to obtain the required engine-induced braking force by more appropriately controlling the rotational speed of the engine shaft of the internal combustion engine.

  Further, the first wheel may be a front wheel and the second wheel may be a rear wheel. That is, according to the present invention, even in a vehicle having an electric motor capable of outputting regenerative braking force only on the rear wheel side, the braking force output to the front and rear wheels is balanced by outputting the engine-induced braking force to the front wheels. It becomes possible to take well.

A vehicle control method according to the present invention is a first control method in which a power of an internal combustion engine and an input shaft connected to an engine shaft of the internal combustion engine is changed with a change in a transmission gear ratio to change one of front wheels and rear wheels. Transmission means capable of outputting to an output shaft connected to the wheels, an electric motor capable of outputting at least regenerative braking force to the second wheel, which is the other of the front wheels and the rear wheels, and the engine shaft of the internal combustion engine A vehicle control method comprising a connected generator, and a power storage means capable of exchanging electric power with the generator and the motor,
When the braking request operation is performed, when the regenerative braking force by the electric motor is used, the engine-induced braking force that is a braking force based on the engine shaft speed control and the generator control via the transmission means Is output to the first wheel and the regenerative braking force by the motor is output to the second wheel to obtain the required braking force requested by the braking request operation. The means and the generator are controlled.

  If the engine shaft rotation speed control and the generator control are performed via the speed change means when the regenerative braking force by the electric motor is output to the second wheel as in this method, the engine brake of the internal combustion engine The engine-induced braking force, which is the sum of the braking force or the braking force generated by the engine brake and the regenerative braking force generated by the generator, is output to the first wheel to balance the braking force between the first wheel and the second wheel. As a result, the behavior of the vehicle during braking can be stabilized. Further, according to this method, it is possible to charge the power storage means using electric power obtained by controlling the generator in addition to regenerative electric power generated by the electric motor during braking.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present invention. In the hybrid vehicle 20 of the embodiment, the power from the engine 22 is transmitted to the front wheels via a torque converter 30, a forward / reverse switching mechanism 35, a belt-type continuously variable transmission (hereinafter referred to as “CVT”) 40, a gear mechanism 61, and a differential gear 62. Front wheel drive system 21 that outputs to 65a, 65b, rear wheel drive system 51 that outputs power from motor 50 to rear wheels 65c, 65d via gear mechanism 63, differential gear 64 and rear shaft 66, front wheels 65a, An electronically controlled hydraulic brake unit 100 for applying braking force to 65b and the rear wheels 65c and 65d, and a hybrid electronic control unit (hereinafter referred to as “hybrid ECU”) 70 for controlling the entire hybrid vehicle 20 Prepare.

  The engine 22 is configured as an internal combustion engine that outputs power using a hydrocarbon-based fuel such as gasoline or light oil, and a crankshaft 23 that is an output shaft of the engine 22 is connected to a torque converter 30. A starter motor 26 is connected to the crankshaft 23 via a gear train 25, and an alternator 28 and a mechanical oil pump 29 are connected via a belt 27 and the like. The engine 22 is operation-controlled by an engine electronic control unit (hereinafter referred to as “engine ECU”) 24, and the engine ECU 24 operates the engine 22 such as a crank position signal from a crank position sensor 23 a attached to the crankshaft 23. The fuel injection amount, ignition timing, intake air amount, and the like are controlled based on signals from various sensors that detect the state. Further, the engine ECU 24 is in communication with the hybrid ECU 70, controls the operation of the engine 22 in accordance with a control signal from the hybrid ECU 70, and outputs data related to the operation state of the engine 22 to the hybrid ECU 70 as necessary.

  The torque converter 30 is configured as a well-known fluid type torque converter, and has a hydraulic lockup clutch. The forward / reverse switching mechanism 35 includes a double-pinion planetary gear mechanism 36, a brake B1, and a clutch C1. By turning off the brake B1 of the forward / reverse switching mechanism 35 and turning on the clutch C1, the rotation of the output shaft 34 of the torque converter 30 can be transmitted to the input shaft 41 of the CVT 40 as it is to advance the hybrid vehicle 20. Further, by turning on the brake B1 and turning off the clutch C1, the rotation of the output shaft of the torque converter 30 is converted in the reverse direction and transmitted to the input shaft 41 of the CVT 40, and the hybrid vehicle 20 can be moved backward. Further, the output shaft of the torque converter 30 and the input shaft 41 of the CVT 40 can be disconnected by turning off the brake B1 and turning off the clutch C1.

  The CVT 40 includes a primary pulley 43 that can change the groove width connected to the input shaft 41, a secondary pulley 44 that can similarly change the groove width and is connected to an output shaft 42 as a drive shaft, and a primary pulley 43. And a belt 45 wound around the groove of the secondary pulley 44. If the groove widths of the primary pulley 43 and the secondary pulley 44 are changed by hydraulic oil from a hydraulic circuit 47 that is driven and controlled by a CVT electronic control unit (hereinafter referred to as “CVTECU”) 46, the power input to the input shaft 41 is changed. Can be shifted steplessly and output to the output shaft 42. For example, if the groove width of the primary pulley 43 and the secondary pulley 44 is changed in a state where the fuel supply to the engine 22 is stopped by turning off the accelerator or depressing the brake pedal 85, the crankshaft of the engine 22 via the input shaft 41 or the like. It is also possible to adjust the rotational speed of 23. The hydraulic circuit 47 adjusts the hydraulic pressure and amount of hydraulic oil supplied from the electric oil pump 60 and the mechanical oil pump 29 to adjust the primary pulley 43, the secondary pulley 44, the torque converter 30 (lock-up clutch), and the brake B1. Can be supplied to the clutch C1 and the like. The CVTECU 46 receives, for example, the rotational speed Nin of the input shaft 41 from the rotational speed sensor 48 attached to the input shaft 41 and the rotational speed Nout of the output shaft 42 from the rotational speed sensor 49 attached to the output shaft 42. The CVTECU 46 generates and outputs a drive signal to the hydraulic circuit 47 based on these pieces of information. Further, the CVTECU 46 also performs on / off control of the brake B1 and the clutch C1 of the forward / reverse switching mechanism 35 and lockup control of the torque converter 30. Further, the CVT ECU 46 communicates with the hybrid ECU 70, controls the transmission ratio of the CVT 40 in accordance with a control signal from the hybrid ECU 70, and controls the CVT 40 such as the rotational speed Nin of the input shaft 41 and the rotational speed Nout of the output shaft 42 as necessary. Data relating to the driving state is output to the hybrid ECU 70.

  The motor 50 is a synchronous generator motor that functions not only as a generator but also as a motor. An output terminal is connected to the alternator 28 driven by the engine 22 via the inverter 52 and a power line from the alternator 28. Connected to a high voltage battery (for example, a secondary battery having a rated voltage of 42V). As a result, the motor 50 can be operated by electric power from the alternator 28 and the high voltage battery 55, or can be charged by the electric power generated by performing regenerative braking. The motor 50 is driven and controlled by a motor electronic control unit (hereinafter referred to as “motor ECU”) 53. The motor ECU 53 receives signals necessary for driving and controlling the motor 50, such as a signal from a rotational position detection sensor 50a that detects the rotational position of the rotor of the motor 50, and a motor 50 detected by a current sensor (not shown). A phase current value or the like is input, and the motor ECU 53 generates and outputs a switching signal to the switching element of the inverter 52 based on these signals and the like. Further, the motor ECU 53 communicates with the hybrid ECU 70 and controls the drive of the motor 50 by outputting a switching control signal to the inverter 52 according to the control signal from the hybrid ECU 70 and relates to the operation state of the motor 50 as necessary. Data is output to the hybrid ECU 70. The high voltage battery 55 is connected to a low voltage battery 57 via a DC / DC converter 56 that converts the voltage, so that the electric power from the high voltage battery 55 side is voltage converted and supplied to the low voltage battery 57 side. It has become. The low voltage battery 57 is used as a power source for various auxiliary machines including the electric oil pump 60 described above. The high voltage battery 55 and the low voltage battery 57 are managed by a battery electronic control unit (hereinafter referred to as “battery ECU”) 58. The battery ECU 58 is based on the voltage between terminals from a voltage sensor (not shown) attached to output terminals (not shown) of the batteries 55 and 57, the charge / discharge current from the current sensor, the battery temperature from the temperature sensor, and the like. Capacitance SOC, input / output restrictions, etc. are calculated. Further, the battery ECU 58 communicates with the hybrid ECU 70 and the like, and outputs data such as the remaining capacity SOC to the hybrid ECU 70 and the like as necessary.

  A hydraulic brake unit (hereinafter referred to as “HBS”) 100 includes a master cylinder 101, a brake actuator 102, wheel cylinders 109a to 109d provided on front wheels 65a and 65b, rear wheels 65c and 65d, and the like. The brake actuator 102 of the HBS 100 is a pump or accumulator as a hydraulic pressure generation source (not shown), a master cylinder cut solenoid valve for controlling the communication state between the master cylinder 101 and the wheel cylinders 109a to 109d, and the depression amount of the brake pedal 85. A hybrid simulator based on the brake pedal position BP indicating the amount of depression of the brake pedal 85, the vehicle speed V, etc., regardless of the depression operation of the brake pedal 85 by the driver. The hydraulic pressure applied to the wheel cylinders 109a to 109d is adjusted so that the braking torque corresponding to the share of the braking force to be applied to the HBS 100 acts on the front wheels 65a and 65b and the rear wheels 65c and 65d. It is. In the embodiment, when brake oil is supplied from the brake actuator 102 to the wheel cylinders 109a to 109d, the front / rear wheels 65a and 65b and the rear wheels 65c and 65d usually have a constant front / rear distribution ratio (for example, 7: 3). ) Is applied with braking force. Hereinafter, the ratio of the braking force applied to the rear wheels 65c and 65d of the braking force applied to the front wheels 65a and 65b and the rear wheels 65c and 65d by the HBS 100 is defined as an HBS rear wheel braking force distribution ratio d0 (for example, 0.3). ).

  The brake actuator 102 of the HBS 100 is driven and controlled by a brake electronic control unit (hereinafter referred to as “brake ECU”) 105. The brake ECU 105 includes a master cylinder pressure Pmc from the master cylinder pressure sensor 101a for detecting the master cylinder pressure Pmc, a wheel speed from a wheel speed sensor (not shown) provided on the front wheels 65a and 65b and the rear wheels 65c and 65d, and not shown. The steering angle from the steering angle sensor is input. The brake ECU 105 performs so-called ABS control, traction control (TRC), vehicle stabilization control (VSC), and the like based on these signals. The brake ECU 105 communicates with the hybrid ECU 70 and the like, drives and controls the brake actuator 102 based on a control signal and the like from the hybrid ECU 70, and transmits data and the like regarding the operating state of the brake actuator 102 and the like as necessary. Etc.

  On the other hand, the hybrid ECU 70 is configured as a microprocessor centered on the CPU 72. In addition to the CPU 72, a ROM 74 that stores a processing program, a RAM 76 that temporarily stores data, an input / output port and a communication port (not shown), and the like. With. The hybrid ECU 70 includes an ignition signal from the ignition switch 80, a shift position SP from the shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator pedal from the accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83. The opening degree Acc, the brake pedal position BP from the brake pedal position sensor 86 for detecting the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 87, and the like are input via the input port. The hybrid ECU 70 generates various control signals based on these signals and the like, and exchanges various control signals and data through communication with the engine ECU 24, the CVTECU 46, the motor ECU 53, the battery ECU 58, the brake ECU 105, and the like. The hybrid ECU 70 outputs a drive signal to the starter motor 26 and the alternator 28 connected to the crankshaft 23, a control signal to the electric oil pump 60, and the like via an output port.

  The hybrid vehicle 20 of the embodiment configured as described above travels by outputting the power from the engine 22 to the front wheels 65a and 65b in accordance with the operation of the accelerator pedal 83 by the driver, or the power from the motor 50. Is output to the rear wheels 65c and 65d to travel. The hybrid vehicle 20 of the embodiment can also be driven by four-wheel drive by outputting power from both the engine 22 and the motor 50 as necessary. Examples of traveling by four-wheel drive in this way include sudden acceleration when the accelerator pedal 83 is greatly depressed, or when any of the front wheels 65a and 65b and the rear wheels 65c and 65d slips.

  Next, the operation of the hybrid vehicle 20 of the embodiment configured as described above, particularly the operation at the time of braking when the brake pedal 85 is depressed by the driver will be described. FIG. 2 shows an example of a braking control routine executed by the hybrid ECU 70 of the embodiment. This braking control routine is performed at predetermined time intervals (for example, when the brake pedal 85 is depressed by the driver) (for example, Every several milliseconds).

  At the start of the braking control routine of FIG. 2, the CPU 72 of the hybrid ECU 70 determines the brake pedal position BP from the brake pedal position sensor 86, the vehicle speed V from the vehicle speed sensor 87, the remaining capacity SOC of the high-voltage battery 55, the target rear wheel braking force distribution. Data input processing necessary for control such as the ratio d is executed (step S100). In this case, the remaining capacity SOC of the high voltage battery 55 is input from the battery ECU 58 by communication. The target rear wheel braking force distribution ratio d indicates the ratio of the braking force to be applied to the rear wheels 65c and 65d with respect to the braking force required for the entire hybrid vehicle 20, and the passenger's boarding state, luggage, etc. It is separately set according to the vehicle weight of the hybrid vehicle 20 that changes according to the loading state and is stored in a predetermined storage area.

  After the data input process in step S100, the required braking force BF * requested by the driver is set based on the input brake pedal position BP and the vehicle speed V (step S110). In the embodiment, the relationship between the brake pedal position BP and the vehicle speed V and the required braking force BF * is determined in advance and stored in the ROM 74 as a required braking force setting map (not shown). Those corresponding to the brake pedal position BP and the vehicle speed V are derived and set from the map. Subsequently, the required braking force BFf *, which is the braking force to be applied to the front wheels 65a and 65b, is obtained by multiplying the set required braking force BF * by the value obtained by subtracting the target rear wheel braking force distribution ratio d input from the value 1. At the same time, the required braking force BF * is multiplied by the target rear wheel braking force distribution ratio d to set the rear wheel required braking force BFr *, which is the braking force to be applied to the rear wheels 65d, 65d (step S120). Further, based on the vehicle speed V and the remaining capacity SOC input in step S100, a motor allowable regenerative braking force BFma that is a regenerative braking force that can be output to the motor 50 at that stage is set (step S130). In the embodiment, the relationship between the vehicle speed V and the remaining capacity SOC and the motor allowable regenerative braking force BFma is determined in advance and stored in the ROM 74 as a motor allowable regenerative braking force setting map (not shown) as the motor allowable regenerative braking force BFma. Are derived and set from the map corresponding to the given vehicle speed V and the remaining capacity SOC.

  If the motor allowable regenerative braking force BFma is thus set, it is determined whether or not the set motor allowable regenerative braking force BFma is equal to or greater than the rear wheel required braking force BFr * set in step S120 (step S140). When the motor allowable regenerative braking force BFma is equal to or greater than the rear wheel required braking force BFr *, the rear wheel required braking force BFr * can be provided only by the regenerative braking force by the motor 50. Therefore, if an affirmative determination is made in step S140, the rear wheel required braking force BFr * set in step S120 is set as the motor target regenerative braking force BFm * that is the target value of the regenerative braking force by the motor 50. At the same time, the supplementary braking force BFhb *, which is a share of the required braking force BF * by the HBS 100, is set to 0 (step S150). In contrast, when the motor allowable regenerative braking force BFma is less than the rear wheel required braking force BFr *, the rear wheel required braking force BFr * cannot be provided only by the regenerative braking force by the motor 50. Therefore, if a negative determination is made in step S140, the motor allowable regenerative braking force BFma set in step S130 is set as the motor target regenerative braking force BFm *, and the shortage relative to the rear wheel required braking force BFr * is set. Is obtained by dividing the value obtained by subtracting the motor target regenerative braking force BFm * (= BFma) from the rear wheel required braking force BFr * by the above-described HBS rear wheel braking force distribution ratio d0. This is set as a supplementary braking force BFhb * that is a share of the HBS 100 (step S160).

  Here, in the hybrid vehicle 20 having the motor 50 on the side of the rear wheels 65c and 65d, when the motor 50 outputs the regenerative braking force, it is output to the rear wheels 65c and 65d in order to balance the braking force with respect to the front and rear wheels. It may be necessary to separately apply a braking force according to the regenerative braking force by the motor 50 to the front wheels 65a and 65b. For this reason, in the embodiment, at least the braking force required for the front wheels 65a and 65b is provided by the engine-derived braking force BFae which is a braking force obtained by controlling the rotational speed of the engine 22 (crankshaft 23). After the process of step S150 or S160, the engine-induced braking force BFae is set based on the set front wheel required braking force BFf * and supplementary braking force BFhb * and the HBS rear wheel braking force distribution ratio d0 (step S170). ). In step S170, in consideration of the case where the braking force (complementary braking force) is output from the HBS 100 in addition to the regenerative braking force by the motor 50, the supplementary braking force BFhb * set in step S150 or S160 and the value 1 are set. Is calculated by subtracting the product of the HBS rear wheel braking force distribution ratio d0 from the value obtained by subtracting from the front wheel required braking force BFf * set in step S120 to set the engine-induced braking force BFae. Then, if the engine-derived braking force BFae is set, it is determined whether or not the set engine-derived braking force BFae exceeds the value 0 (step S180). If the engine-derived braking force BFae is less than or equal to 0, Subsequent processing is skipped, and this routine is terminated once.

  On the other hand, when the engine-induced braking force BFae set in step S170 exceeds the value 0, the threshold value Sref related to the remaining capacity SOC of the high-voltage battery 55 is set based on the vehicle speed V input in step S100. (Step S190). The threshold value Sref is generated by controlling the alternator 28 coupled to the crankshaft 23 of the engine 22 to generate electric power when the engine-derived braking force BFae is output as the motor 50 outputs the regenerative braking force. This is for determining whether there is no possibility of overcharging even if the high voltage battery 55 is charged with the electric power generated by the alternator 28. That is, by adjusting the rotational speed of the engine 22 (crankshaft 23) that is in a fuel cut state when the brake pedal 85 is depressed, a braking force (engine brake) based on the friction torque of the engine 22 can be obtained. If the alternator 28 is controlled (torque control), the regenerative braking force by the alternator 28 can also be obtained. However, when the regenerative braking force is output from the alternator 28 in addition to the motor 50, the high-voltage battery 55 is charged by the electric power from both the motor 50 and the alternator 28. Therefore, depending on the value of the remaining capacity SOC. May overcharge the high voltage battery 55. For this reason, in the embodiment, after setting the threshold value Sref as described above, even if the high voltage battery 55 is charged with the electric power generated by the motor 50 and the alternator 28 based on the threshold value Sref, there is a risk of overcharging. It is determined whether or not there is. In the embodiment, the relationship between the vehicle speed V and the threshold value Sref is predetermined based on the motor allowable regenerative braking force BFma for each vehicle speed V, the characteristics of the alternator 28, and the like, and is stored in the ROM 74 as a battery threshold value setting map (not shown). As the threshold value Sref, a value corresponding to a given vehicle speed V is derived and set from the map. If the threshold value Sref is set, it is determined whether or not the remaining capacity SOC input in step S100 is equal to or less than the threshold value Sref (step S200).

  If it is determined in step S200 that the remaining capacity SOC is equal to or less than the threshold value Sref, the remaining capacity of the high voltage battery 55 is relatively small, and the high voltage battery 55 is charged with the power generated by the motor 50 and the alternator 28. It will not be overcharged. For this reason, if an affirmative determination is made in step S200, the engine-induced braking force BFae is obtained from the friction torque (engine braking) by the engine 22 in the fuel cut state and the regenerative braking force obtained by controlling the alternator 28. In order to cover this, a target rotational speed Ne * of the engine 22 (crankshaft 23) and a torque command Talt * for the alternator 28 are set (step S210). In the embodiment, the relationship between the rotational speed of the engine 22 and the braking force based on the friction torque of the engine 22 (for engine braking, see the one-dot chain line in FIG. 3) and the regenerative braking force by the alternator 28 (see the two-dot chain line in FIG. 3). The first engine target rotational speed setting as exemplified in FIG. 3 is established in advance with the relationship between the engine-derived braking force BFae and the target rotational speed Ne * of the engine 22 when the regenerative braking force is output to the alternator 28 based on It is stored in the ROM 74 as a map for use. In step S210, the target engine speed Ne * of the engine 22 corresponding to the engine-induced braking force BFae set in step S170 is derived and set from the first engine target engine speed setting map. In the embodiment, the relationship between the target rotational speed Ne * of the engine 22 and the torque command Talt * for the alternator 28 is predetermined and stored in the ROM 74 as a torque command setting map (not shown). As the command Talt *, a command corresponding to the set target rotational speed Ne * is derived and set from the map.

  On the other hand, when it is determined in step S200 that the remaining capacity SOC exceeds the threshold value Sref, the remaining capacity of the high voltage battery 55 is relatively large, and the high voltage battery 55 is charged with the electric power generated by the motor 50 and the alternator 28. Then, there is a risk of overcharging. For this reason, if a negative determination is made in step S200, the target of the engine 22 is such that the engine-derived braking force BFae can be covered only by the braking force based on the friction torque (engine brake) by the engine 22 in the fuel cut state. The rotational speed Ne * is set, and the torque command Talt * for the alternator 28 is set to 0 (step S220). In the embodiment, the engine-induced braking force BFae when the regenerative braking force is not output to the alternator 28 based on the relationship between the rotational speed of the engine 22 and the braking force based on the friction torque of the engine 22 and the target rotational speed Ne * of the engine 22. Is stored in the ROM 74 as a second engine target speed setting map as illustrated in FIG. In step S220, the target engine speed Ne * of the engine 22 corresponding to the engine-induced braking force BFae set in step S170 is derived and set from the second engine target engine speed setting map.

  As described above, if the target rotational speed Ne * and the torque command Talt * are set in step S210 or S220, the target gear ratio γ * in the CVT 40 is set based on the set target rotational speed Ne * of the engine 22. (Step S230). In the embodiment, the relationship between the target rotational speed Ne * of the engine 22 and the target speed ratio γ * is determined in advance and stored in the ROM 74 as a speed ratio setting map (not shown). A value corresponding to the target rotational speed Ne * set in S210 or S220 is derived and set from the map. Then, the set motor target regenerative braking force BFm * is transmitted to the motor ECU 53, the supplementary braking force BFhb * is transmitted to the brake ECU 105, the target gear ratio γ * is transmitted to the CVTECU 46, and a control signal based on the torque command Talt * is transmitted to the alternator 28. (Step S240), this routine is temporarily terminated. The motor ECU 53 that has received the motor target regenerative braking force BFm * performs switching control of the switching element of the inverter 52 so as to obtain the motor target regenerative braking force BFm *, and the brake ECU 105 obtains the supplementary braking force BFhb *. The brake actuator 102 is controlled as described above. Further, the CVT ECU 46 that has received the target gear ratio γ * controls the hydraulic circuit 47 so that the groove widths of the primary pulley 43 and the secondary pulley 44 are changed according to the target gear ratio γ *.

  When the braking control routine of FIG. 2 is executed as described above, if the motor allowable regenerative braking force BFma is equal to or greater than the rear wheel required braking force BFr *, the supplementary braking force BFhb * by the HBS 100 is not required ( S150), the ratio between the engine-induced braking force BFhb * for the front wheels 65a and 65b and the motor target regenerative braking force BF * for the rear wheels 65c and 65 corresponds to the target rear wheel braking force distribution ratio d (1-d: The motor 50, the CVT 40, and the alternator 28 are controlled so as to satisfy d). If the motor allowable regenerative braking force BFma is less than the rear wheel required braking force BFr *, the supplementary braking force BFhb * by the HBS 100 is required (S160). In this case, the engine-induced control for the front wheels 65a and 65b is required. The sum of the power BFhb * and the braking force from the HBS 100 ((1-d0) · BFhb *), the motor target regenerative braking force BF * for the rear wheels 65c and 65d, and the braking force from the HBS 100 (d0 · BFhb *) The motor 50, the CVT 40, the alternator 28, and the brake actuator 102 are controlled such that the ratio to the sum of the two becomes a ratio (1-d: d) corresponding to the target rear wheel braking force distribution ratio d.

  As described above, in the hybrid vehicle 20 of the embodiment, when the regenerative braking force by the motor 50 is used when the brake pedal 85 is depressed, the rotational speed control and alternator of the engine 22 (crankshaft 23) via the CVT 40 are used. The engine-induced braking force, which is the braking force based on the control (step S210 or S220), is output to the front wheels 65a and 65b, and the regenerative braking force by the motor 50 is output to the rear wheels 65c and 65d, so that the required braking force BF * is obtained. The motor 50, CVT 40, and alternator 28 are controlled so as to be obtained. As described above, when the rotational speed control of the engine 22 and the control of the alternator 28 (torque control) via the CVT 40 are performed when the regenerative braking force by the motor 50 is output to the rear wheels 65c and 65d, the engine 22 The braking force generated by the engine brake (friction torque) or the sum of the braking force generated by the engine brake and the regenerative braking force generated by the alternator 28 is output to the front wheels 65a and 65b to balance the braking force between the front and rear wheels. As a result, it is possible to stabilize the behavior of the hybrid vehicle 20 during braking by suppressing the locking of the rear wheels 65c and 65d.

  In the hybrid vehicle 20 of the embodiment, the ratio between the braking force output to the front wheels 65a and 65b and the braking force output to the rear wheels 65c and 65d is equal to the rear wheel regardless of the presence or absence of the supplementary braking force by the HBS 100. Since at least the motor 50, the CVT 40, and the alternator 28 are controlled so as to have a ratio (1-d: d) corresponding to the target braking force distribution ratio d, the braking force is more appropriately distributed to the front and rear wheels. It is possible to improve the braking performance and to adopt a HBS 100 having a relatively simple configuration. Furthermore, in the hybrid vehicle 20 of the embodiment, if the motor allowable regenerative braking force BFma is less than the rear wheel required braking force BFr *, the braking force by the HBS 100 is used, the engine-induced braking force, the regenerative braking force by the motor 50, and the HBS 100. Therefore, the required braking force BF * requested by the braking force of is ensured satisfactorily.

  Further, as in the embodiment, when regenerative braking by the alternator 28 is also used according to the remaining capacity SOC of the high voltage battery 55 when the engine-induced braking force is output, the high pressure is generated using the power generated by the alternator 28. It is also possible to charge the battery 55. In the above embodiment, the motor target regenerative braking force BFm * of the motor 50 is set according to the remaining capacity SOC of the high voltage battery 55 (steps S130 to S160), and the regenerator 28 regenerates according to the remaining capacity SOC. Since the target rotational speed Ne * and the torque command Talt * that define the braking force are set (step S210 or S220), overcharge of the high-voltage battery 55 can be suppressed and deterioration thereof can be suppressed.

  In the above embodiment, when the brake pedal 85 is depressed, the regenerative braking force by the motor 50 is first used, and the braking force by the HBS 100 is also used according to the required braking force BF *. However, it is not limited to this. That is, as a hydraulic brake unit, an operation braking force based on a master cylinder pressure (operation pressure), which is a pressure of brake oil generated in the master cylinder in response to a braking request operation by communicating the master cylinder and each wheel cylinder normally. A simpler one that outputs the front and rear wheels with a predetermined front and rear distribution ratio may be used. In this case, for example, the required braking force BF * is set based on the depression force of the brake pedal 85 corresponding to the master cylinder pressure or the like, and the regenerative braking force by the motor 50 is applied when the required braking force BF * cannot be covered by the operating braking force. At this time, the sum of the engine-induced braking force output to the front wheels 65a and 65b and the braking force from the hydraulic brake unit, the regenerative braking force output to the rear wheels 65c and 65d, and the hydraulic brake unit are used. The motor 50, the CVT 40, and the alternator 28 may be controlled so that the ratio to the sum of the braking force becomes the target front / rear distribution ratio. Such a hydraulic brake unit is generated by pressurizing a pump having a pump as pressurizing means capable of pressurizing brake oil from the master cylinder in addition to a master cylinder as operating pressure generating means. The braking force may be output using a pressurizing pressure that is the pressure of the brake oil. When such a hydraulic brake unit is used, when the required braking force BF * cannot be provided by the operation braking force and the regenerative braking force (and the engine-induced braking force) by the motor 50, the pump is operated to brake the master cylinder. The required braking force BF * can be obtained by pressurizing the oil. Further, when a hydraulic brake unit that outputs such an operating braking force to the front and rear wheels with a constant front / rear distribution ratio is used, the engine-induced braking force output to the front wheels 65a and 65b and the rear wheel 65c and 65d are output. The motor 50, the CVT 40, and the alternator 28 may be controlled so that only the ratio to the regenerative braking force becomes the predetermined front / rear distribution ratio or another target front / rear distribution ratio. That is, the ratio of the braking force output to the front wheels 65a and 65b and the braking force output to the rear wheels 65c and 65d does not necessarily coincide with the target front / rear distribution ratio.

  So far, the present invention has been described by taking the operation when the brake pedal 85 is depressed as an example, but the braking control routine of FIG. 2 applies the braking force based on the accelerator-off operation when the depression of the accelerator pedal is released. Needless to say, it can also be applied to output. Further, instead of the belt type CVT 40, a toroidal type CVT may be used. Thus, if a continuously variable transmission that can change the gear ratio steplessly is used, the required engine-induced braking force can be obtained by more appropriately controlling the rotational speed of the engine 22 (crankshaft 23). Needless to say, a stepped automatic transmission may be used instead of the CVT 40. Further, the hybrid vehicle 20 of the embodiment includes a motor 50 capable of outputting a regenerative braking force only on the rear wheels 65c and 65d side, and outputs the engine-derived braking force to the front wheels 65a and 65b to output to the front and rear wheels. However, the present invention is not limited to this. That is, the present invention can be applied to a vehicle that outputs the power of the engine 22 to the rear wheels 65c and 65d via the rear shaft 66 and outputs the power (regenerative braking force) of the motor 50 to the front wheels 65a and 65b. .

  The embodiments of the present invention have been described above using the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the present invention. Needless to say.

  The present invention is useful in the automotive industry.

1 is a schematic configuration diagram of a hybrid vehicle 20 according to an embodiment of the present invention. It is a flowchart which shows an example of the braking control routine performed by hybrid ECU70 of an Example. It is explanatory drawing which shows an example of the map for 1st engine target speed setting. It is explanatory drawing which shows an example of the 2nd engine target rotation speed setting map.

Explanation of symbols

  20 hybrid vehicle, 21 front wheel drive system, 22 engine, 22a intake manifold, 23 crankshaft, 23a crank position sensor, 24 engine electronic control unit (engine ECU), 25 gear train, 26 starter motor, 27 belt, 28 alternator, 29 mechanical oil pump, 30 torque converter, 34 output shaft, 35 forward / reverse switching mechanism, 36 planetary gear mechanism, 40 CVT, 41 input shaft, 42 output shaft, 43 primary pulley, 44 secondary pulley, 45 belt, 46 for CVT Electronic control unit (CVTECU), 47 Hydraulic circuit, 50 motor, 50a Rotation position detection sensor, 51 Rear wheel drive, 52 Inverter, 53 Electronic control unit for motor (motor EC U), 55 high voltage battery, 56 DC / DC converter, 57 low voltage battery, 58 electronic control unit for battery (battery ECU), 60 electric oil pump, 61, 63 gear mechanism, 62, 64 differential gear, 65a, 65b front wheel, 65c, 65d Rear wheel, 66 Rear axle, 70 Hybrid electronic control unit (hybrid ECU), 72 CPU, 74 ROM, 76 RAM, 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal Position sensor, 85 Brake pedal, 86 Brake pedal position sensor, 87 Vehicle speed sensor, 100 Hydraulic brake unit (HBS), 101 Master cylinder, 101a, 101b Master cylinder pressure Sensor, 102 brake actuator, 103 brake booster, 103a pressure sensor, 104 check valve, 105 electronic control unit for brake (brake ECU), 106 reservoir, 109a, 109b, 109c, 109d wheel cylinder, 110 first system, 111, 121 MC cut solenoid valve, 112a, 112d, 122b, 122c Holding solenoid valve, 113a, 113d, 123b, 123c Pressure reducing solenoid valve, 114, 124 Reservoir, 115, 125 Pump, 116, 126 Check valve, 120 Second system, B1 brake, C1 clutch, L10, L11, L20, L21 supply oil passage, L12a, L12d, L22b, L22c pressure increase / decrease oil passage, L13, L23 pressure reduction oil passage, L14, L15, 16, L24, L25, L26 oil passage.

Claims (8)

An internal combustion engine;
A shift capable of shifting the power of the input shaft connected to the engine shaft of the internal combustion engine with a change in the gear ratio and outputting it to the output shaft connected to the first wheel which is either the front wheel or the rear wheel. Means,
An electric motor capable of outputting at least a regenerative braking force to a second wheel which is the other of the front wheel and the rear wheel;
A generator coupled to the engine shaft of the internal combustion engine;
Power storage means capable of exchanging power with the generator and the motor;
Requested braking force setting means for setting a requested braking force requested by a braking request operation;
When the regenerative braking force by the electric motor is used when the braking request operation is performed, the engine is a braking force based on the rotational speed control of the engine shaft and the control of the generator via the transmission means. The motor, the speed change means, and the motor are configured so that a braking force is output to the first wheel and the regenerative braking force by the motor is output to the second wheel to obtain the set required braking force. Braking control means for controlling the generator;
A vehicle comprising:   The braking control means is configured to cause the electric motor so that a ratio between an engine-induced braking force output to the first wheel and the regenerative braking force output to the second wheel becomes a predetermined target front-rear distribution ratio. The vehicle according to claim 1, wherein the speed change means and the generator can be controlled. The vehicle according to claim 1 or 2,
Fluid pressure braking means capable of outputting a braking force to the first wheel and the second wheel;
The brake control means uses the engine-induced braking force and the regenerative braking force when the regenerative braking force by the electric motor and the fluid pressure braking force by the fluid pressure braking means are used when the braking request operation is performed. A vehicle that controls at least the electric motor, the transmission means, and the generator so that the set required braking force is covered by the braking force and the fluid pressure braking force. The vehicle according to claim 3, wherein
The fluid pressure type braking means can apply a braking force to the first wheel and the second wheel with a substantially constant front-rear distribution ratio,
The braking control means uses the engine-induced braking force output to the first wheel and the fluid pressure control when the regenerative braking force and the fluid pressure braking force by the electric motor are used when the braking request operation is performed. At least the electric motor, the transmission unit, and the transmission unit so that a ratio of a sum of power and a sum of the regenerative braking force and the fluid pressure braking force output to the second wheel is a predetermined target front-rear distribution ratio. A vehicle that controls the generator.   The vehicle according to any one of claims 1 to 4, wherein the braking control means sets the regenerative braking force by the electric motor and the regenerative braking force by the generator according to the remaining capacity of the power storage means.   The vehicle according to any one of claims 1 to 5, wherein the speed change means is a continuously variable transmission capable of changing the speed ratio steplessly.   The vehicle according to any one of claims 1 to 6, wherein the first wheel is a front wheel and the second wheel is a rear wheel. An internal combustion engine and an output shaft connected to a first wheel that is one of a front wheel and a rear wheel by shifting the power of an input shaft connected to the engine shaft of the internal combustion engine with a change in gear ratio A transmission means capable of outputting; an electric motor capable of outputting at least a regenerative braking force to the second wheel which is the other of the front wheels and the rear wheels; a generator connected to the engine shaft of the internal combustion engine; A vehicle and a power storage means capable of exchanging electric power with the electric motor,
When the braking request operation is performed, when the regenerative braking force by the electric motor is used, the engine-induced braking force that is a braking force based on the engine shaft speed control and the generator control via the transmission means Is output to the first wheel and the regenerative braking force by the motor is output to the second wheel to obtain the required braking force requested by the braking request operation. A vehicle control method for controlling means and the generator.

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