JP2002095106A - Braking force controller for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop regenerative braking properly when vehicle speed is at a predetermined level or below by considering the operation mode of a hybrid engine. SOLUTION: In a vehicle of which front wheels are driven by the hybrid engine 10 including a motor generator for regenerative braking, front wheel target braking force Fbft is computed (S20) based on at least braking requirements of an operator, and the front wheel regenerative target braking force Frgft is computed as a smaller value of Fbft and maximum regenerative braking force Frgfmax (S110). The maximum regenerative braking force Frgfmax is set so as to be reduced to 0 gradually with decreasing vehicle speed V, when the vehicle speed is at or below the predetermined level to perform guard control which stops the regenerative braking in a low speed zone. The predetermined level in the operating mode which cannot stop a gasoline engine 12 of the hybrid engine 10 is set to a higher level than that in normal operation for regenerative braking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a braking force control device for a vehicle, and more particularly to a braking force control device for a vehicle equipped with a hybrid engine including a regenerative braking motor generator.

[0002]

2. Description of the Related Art As one of braking force control devices for vehicles such as automobiles, a motor generator of a hybrid engine is used as a motor generator for regenerative braking, as described in, for example, Japanese Patent Application Laid-Open No. H11-289608. A braking force control device configured to be operated is conventionally known.

According to such a braking force control device, the motor generator of the hybrid engine is used as the motor generator for regenerative braking, so that the drive source is appropriately used according to the running condition of the vehicle and the regenerative braking is performed. Is performed, the fuel efficiency of the entire vehicle can be improved as compared with a vehicle in which only an internal combustion engine is used as a drive source and regenerative braking is not performed.

[0004]

In general, regenerative braking cannot be performed accurately in a low vehicle speed range, so regenerative braking is stopped when the vehicle speed is lower than a predetermined value (guard control). It must be. In particular, when the regenerative braking generator is a motor generator incorporated in a hybrid engine, the predetermined value of the vehicle speed at which regenerative braking becomes impossible depends on the operation mode of the hybrid engine. However, in the conventional braking force control device as described above, since this is not taken into account, there is a problem that the regenerative braking is not properly stopped according to the operation mode of the hybrid engine.

[0005] For example, if the predetermined value is set to a certain low value, regenerative braking is controlled to be executed even in a region where the vehicle speed is low. Therefore, depending on the operation mode of the hybrid engine, regenerative braking is properly performed. Conversely, if the predetermined value is set to a certain high value, regenerative braking will not be performed even though proper regenerative braking is possible depending on the operation mode of the hybrid engine, so that the regenerative efficiency of the vehicle will be reduced. It will be lower.

The present invention has been made in view of the above-mentioned problems in a conventional braking force control device in which a motor generator of a hybrid engine is used as a motor generator for regenerative braking. The main problem is to appropriately stop the regenerative braking when the vehicle speed is equal to or lower than a predetermined value by considering the operation mode of the hybrid engine.

[0007]

According to the present invention, there is provided a braking force control system for a vehicle equipped with a hybrid engine including a regenerative braking motor generator. In a braking force control device for a vehicle that performs a guard control for stopping regenerative braking when a vehicle speed is equal to or lower than a predetermined value, the predetermined value is changed according to an operation mode of the hybrid engine. This is achieved by the braking force control device.

According to the first aspect of the present invention, in a vehicle braking force control device for performing a guard control for stopping regenerative braking when the vehicle speed is equal to or lower than a predetermined value, the predetermined value is set according to the operation mode of the hybrid engine. Since it is changed, the predetermined value is optimally set according to the operation mode of the hybrid engine, whereby the guard control is optimally executed according to the operation mode of the hybrid engine.

Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the first aspect, when the driver performs a braking operation, the operation of the hybrid engine is performed. Even in a situation where the mode changes and the predetermined value changes to a small value, the guard control is continued at a large predetermined value corresponding to the operation mode before the change (the configuration of claim 2).

According to the second aspect of the present invention, even when the operation mode of the hybrid engine changes and the predetermined value changes to a small value when the driver performs the braking operation, the operation before the change is performed. Since the guard control is continued at a large predetermined value corresponding to the mode, a sudden increase in the regenerative braking force due to a change in the operation mode is reliably prevented.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the configuration of the above-mentioned claim 2, the guard control is continued at the large predetermined value. Also, when the vehicle speed becomes higher than the large predetermined value, the predetermined value is changed to a small predetermined value corresponding to the current operation mode.

According to the third aspect of the present invention, even when the guard control is continued at a large predetermined value, when the vehicle speed becomes higher than the high predetermined value, the predetermined value corresponds to the current driving mode. Will be changed to a smaller predetermined value.
The regenerative braking is executed, and therefore, even in such a situation, the regenerative efficiency is improved as compared with the case where the guard control is continued at a large predetermined value.

According to the present invention, in order to effectively achieve the above-described main object, in the above-described configuration of the first aspect, the vehicle speed may be reduced to a predetermined value or less in a situation where regenerative braking is performed. In this case, the regenerative braking force is gradually reduced, and a change in the operation mode of the hybrid engine in which the predetermined value changes to a large value until the regenerative braking force becomes 0 is configured to be prohibited (the configuration of claim 4). ).

According to the fourth aspect of the present invention, when the vehicle speed falls below a predetermined value in a situation where regenerative braking is being performed, the regenerative braking force is gradually reduced and a predetermined value is maintained until the regenerative braking force becomes zero. Since the change of the operation mode of the hybrid engine whose value changes to a large value is prohibited, the sudden decrease of the regenerative braking force due to the change of the operation mode is reliably prevented.

[0015]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the hybrid engine includes an internal combustion engine, and an operation mode of the hybrid engine is such that the internal combustion engine operates for regenerative braking. And a driving mode in which the operation of the internal combustion engine cannot be stopped (preferred mode 1).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1, the braking force control device is configured such that the operation mode of the hybrid engine is such that the operation of the internal combustion engine can be stopped. , The predetermined value is set to a small value, and when the operation mode of the hybrid engine is an operation mode in which the operation of the internal combustion engine cannot be stopped, the predetermined value is set to a large value. 2).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1, the braking force control device includes an operation mode in which the operation mode of the hybrid engine can stop the operation of the internal combustion engine. When, the predetermined value is set to a small value, the maximum regenerative braking force is calculated based on the vehicle speed from the relationship between the maximum regenerative braking force and the vehicle speed when the predetermined value is a small value, and the operation mode of the hybrid engine is When the engine is in an operation mode in which the operation of the engine cannot be stopped, the predetermined value is set to a large value, and when the predetermined value is a large value, the maximum regeneration is performed based on the vehicle speed based on the relationship between the maximum regenerative braking force and the vehicle speed. The braking force is calculated, and the motor generator for regenerative braking is controlled based on the maximum regenerative braking force (preferred embodiment 3).

According to another preferred embodiment of the present invention, in the configuration of the first aspect, the hybrid engine drives only one of the front wheel and the rear wheel, and regenerative braking is performed on the other of the front wheel and the rear wheel. And a braking force control device is configured to change the predetermined value only for the regenerative braking motor generator included in the hybrid engine in accordance with the operation mode of the hybrid engine (preferred mode 4).

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of a braking force control device according to the present invention applied to a front wheel drive type vehicle equipped with a hybrid engine.

In FIG. 1, reference numeral 10 denotes a hybrid engine for driving front wheels, and the hybrid engine 10 includes a gasoline engine 12 and a motor generator 14. An output shaft 16 of the gasoline engine 12 is connected to an input shaft of a continuously variable transmission 18 having a built-in clutch.
The input shaft of the continuously variable transmission 18 is connected to the output shaft 20 of the motor generator 14.
Is also linked. The rotation of the output shaft 19 of the continuously variable transmission 18 is transmitted to the left and right front wheel axles 24FL and 24FR via the front differential 22, whereby the left and right front wheels 24FL and 24FR are rotationally driven.

The gasoline engine 12 and the motor generator 14 of the hybrid engine 10 are controlled by an engine control device 28 in accordance with the driver's depression amount of an accelerator pedal (not shown) and the running condition of the vehicle.
The motor generator 14 also functions as a generator of the regenerative braking device 30 for a front wheel, and functions as a regenerative generator (regenerative braking).
Is also controlled by the engine control device 28.

In particular, in the illustrated embodiment, the hybrid engine 10 has a gasoline engine 12 during normal running with a shift lever (not shown) in the D range.
Alternatively, a driving force or an engine braking force is generated by the gasoline engine 12 and the motor generator 14 (normal operation mode), and when the shift lever is in the D range but the load is low, the driving force is generated only by the motor generator 14 ( In the electric vehicle mode), the driving force or the engine braking force is generated by the gasoline engine 12 and the motor generator 14 even when the shift lever is in the B range. In this case, the engine braking force is higher than that in the D range. In the engine brake mode, the motor generator 14 also functions as a regenerative generator when the shift lever is in the D range and the brake pedal 32 is depressed by the driver.

The electric energy generated by the regeneration by the motor generator 14 is charged in the battery 15, and when the voltage of the battery 15 drops below the reference value, the motor generator 14 is driven by the gasoline engine 12, whereby the battery 15 is charged (charge mode).

In FIG. 1, the rotation of left and right rear wheels 34RL and 34RR, which are driven wheels, is controlled by left and right rear wheel axles 36RL, 3RL.
The power is transmitted to the motor generator 42 of the rear wheel regenerative braking device 40 via the 6RR and the rear wheel differential 38. The regenerative braking by the motor generator 42 is also controlled by the engine control device 28, and thus the engine control device 28 functions as a control device for the regenerative braking device.

The friction braking force of the left and right front wheels 26FL, 26FR and the left and right rear wheels 34RL, 34RR is controlled by the hydraulic circuit 46 of the friction braking device 44 to the corresponding wheel cylinders 48FL, 48.
It is controlled by controlling the braking pressure of FR, 48RL, 48RR. Although not shown in the figure, the hydraulic circuit 46 includes a reservoir, an oil pump, various valve devices, and the like. The braking pressure of each wheel cylinder is normally set by the amount of depression of the brake pedal 32 by the driver and the brake pedal 32.
Is controlled by a braking control device 52 as a friction braking device control device in accordance with the pressure of the master cylinder 50 driven in accordance with the depression of the brake pedal.

The engine control device 28 has a vehicle speed sensor 54.
A signal indicating the vehicle speed V and a signal indicating the voltage of the battery 15 are input from the voltage sensor 56. Further, although not shown, a signal indicating the amount of depression of the accelerator pedal from the accelerator pedal sensor, and a continuously variable signal from the shift position sensor A signal indicating the shift position of the transmission 18 and the like are input, and further, a signal indicating the target regenerative braking force Frgft for the front wheels and the target regenerative braking force Frgrt for the rear wheels is input from the braking control device 52.

The braking control device 52 includes the engine control device 2
8, information on the operation mode of the hybrid engine 10, a signal indicating whether regenerative braking by the front wheel regenerative braking device 30 is possible, and a signal indicating the actual regenerative braking force are input from the stroke sensor 58. 32, a signal indicating a depression stroke Sp of 32, a signal indicating the pressure Pm of the master cylinder 50 from the pressure sensor 60,
Left and right front wheel and left and right rear wheel cylinders 48FL, 48FR, 4 from pressure sensors 62fl, 62fr, 62rl, 62rr.
Signals indicating the braking pressures Pfl, Pfr, Prl, and Prr of 8RL and 48RR are input, respectively.

The engine control device 28 and the brake control device 52 are actually, for example, CPU, ROM, RA
M, a general configuration including a microcomputer including an input / output device and a drive circuit may be used.

As will be described later in detail, the braking control device 5
2 calculates the final target deceleration Gt of the vehicle, which is the driver's braking demand, based on the depression stroke Sp of the brake pedal 32 and the master cylinder pressure Pm in accordance with the routine shown in FIGS. The target braking forces Fbft and Fbrt for the front and rear wheels are calculated based on the target deceleration Gt and a predetermined front and rear wheel braking force distribution ratio.

The braking control device 52 determines whether or not the regenerative braking by the regenerative braking device 30 is possible based on a signal input from the engine control device 28, and determines whether or not the regenerative braking is possible. The target regenerative braking force Frgft for the front wheels and the target regenerative braking force F for the rear wheels
rgrt is gradually reduced to 0, and the target regenerative braking force is maintained at 0 until regenerative braking is possible.

Further, the braking control device 52 is configured to control the gasoline engine 1 based on a signal input from the engine control device 28.
It is determined whether or not the regenerative braking device 30 of the front wheels can be stopped in a normal state in which the operation of the gasoline engine 12 can be stopped. The regenerative braking force (guard value) Frgfmax is set to the value indicated by the solid line in FIG.
In a situation (for example, a charging mode) where the operation of the second wheel cannot be stopped, the maximum regenerative braking force Frgfm of the regenerative braking device 30 for the front wheels
ax is set to the value indicated by the broken line in FIG.

In FIG. 4, V as a small predetermined value
n indicates a threshold at which the regenerative braking cannot be performed properly when the vehicle speed V falls below the value in a normal situation in which the operation of the gasoline engine 12 can be stopped. When the vehicle speed V falls below the value in a situation where the operation of the engine 12 cannot be stopped, the threshold value indicates that the regenerative braking cannot be properly performed.

Then, the braking control device 52 sets the target braking force Fbf
The smaller of t and the maximum regenerative braking force Frgfmax is calculated as the target regenerative braking force Frgft for the front wheels, and the maximum regenerative braking force of the regenerative braking device 40 for the rear wheels is set as Frgrmax, and the target braking force Fbrt and the maximum regenerative braking force are calculated. The smaller value of Frgrmax is calculated as the target regenerative braking force Frgrt of the rear wheels, and a signal indicating the target regenerative braking force is sent to the engine controller 28.
Output to

The engine control device 28 controls the motor generator 14 of the regenerative braking device 30 for the front wheel with the target regenerative braking force Frgft for the front wheel as an upper limit, and the actual regenerative braking device 30 for the front wheel operates based on the generated voltage and generated current. Regenerative braking force Frg
Calculate fa. Similarly, the engine control device 28 sets the rear wheel regenerative braking device 4 with the target regenerative braking force Frgrt of the rear wheel as an upper limit.
The regenerative braking force Frgra by the regenerative braking device 40 for the rear wheels is calculated based on the generated voltage and the generated current. Further, the engine control device 28 outputs signals indicating the actual regenerative braking forces Frgfa and Frgra to the braking control device 52.

The braking control unit 52 calculates a value obtained by subtracting the actual regenerative braking force Frgfa from the target braking force Fbft as a target friction braking force Fbpft for the front wheels, and subtracts the actual regenerative braking force Frgra from the target braking force Fbrt. The calculated value is calculated as the target frictional braking force Fbprt of the rear wheel, and the target frictional braking force F of the front wheel is calculated.
Target braking pressure Pbtfl and Pbtfr for left and right front wheels based on bpft
And the target braking pressures Pbtrl and Pbtrr of the left and right rear wheels are calculated based on the target frictional braking force Fbprt of the rear wheels, and the braking pressures Pi (i = fl, fr, rl, r) of the left and right front wheels and the left and right rear wheels are calculated.
r) is the corresponding target braking pressure Pbti (i = fl, f
r, rl, rr) to control the braking pressure of each wheel.

In particular, in the illustrated embodiment, when the braking operation is performed by the driver, the braking control device 52 changes the operation mode of the hybrid engine 10 to change the predetermined value from Vh to Vn. Also in this case, by continuing the guard control with Vh as a predetermined value, the maximum regenerative braking force of the regenerative braking device 30 for the front wheels is calculated from a map corresponding to the graph shown by the broken line in FIG. Thus, even in the situation where the guard control is continued with Vh as a predetermined value, when the vehicle speed V becomes higher than Vh, the predetermined value is changed to Vn, and the maximum regenerative braking force of the regenerative braking device 30 for the front wheels is plotted. The calculation is performed from the map corresponding to the graph shown by the solid line in FIG.

Further, when the vehicle speed V becomes equal to or lower than the predetermined value Vn in a state where regenerative braking is performed in an operation mode in which the operation of the gasoline engine 12 can be stopped, the brake control device 52 sets the target regenerative braking force Frgft. And Frgrt are gradually reduced,
The engine controller 28 controls the hybrid engine 1 in which the predetermined value changes from Vn to Vh until the target regenerative braking force becomes zero.
The change of the operation mode of 0 is prohibited, and the change of the operation mode is permitted when the target regenerative braking force becomes 0.

Note that the control of the operation mode of the hybrid engine 10 and the control of the gasoline engine 12 by the engine control device 28 do not constitute the gist of the present invention, and these controls may be performed by any known method in the art. It may be implemented in the same way.

Next, with reference to the flowcharts shown in FIGS. 2 and 3, the brake control device 52 in the illustrated embodiment will be described.
Will be described. The control according to the flowcharts shown in FIGS. 2 and 3 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 10, a signal indicating the depression stroke Sp of the brake pedal 32 detected by the stroke sensor 58 and a signal indicating the pressure Pm of the master cylinder 50 detected by the pressure sensor 60 are read. In step 20, the target braking force Fbft for the front wheels and the target braking force Fbrt for the rear wheels are calculated in accordance with the routine shown in FIG.

In step 40, it is determined whether or not the regenerative braking of the front wheel regenerative braking device 30 and the rear wheel regenerative braking device 40 is possible. If an affirmative determination is made, the process proceeds to step 60. , Negative judgment, that is, the regenerative braking device 3
When it is determined that the regenerative braking of 0 or 40 is impossible, in step 50, the target regenerative braking force Frgft of the front wheel and the target regenerative braking force Frgrt of the rear wheel are set to a predetermined value ΔFrgf and The value is gradually reduced by subtracting ΔFrgr, and then the process proceeds to step 120.

In step 60, it is determined whether or not the operation of the gasoline engine 12 can be stopped in order to perform regenerative braking of the front wheels. If the determination is affirmative, the process proceeds to step 80. If a negative determination is made, in step 70, the guard value Frgfmax of the target regenerative braking force of the front wheels is calculated from a map corresponding to the graph shown by the broken line in FIG. .

In step 80, for example, it is determined whether or not the braking operation by the driver has been performed by determining whether or not the depression stroke Sp and the master cylinder pressure Pm are respectively smaller than the reference values. When an affirmative determination is made, the routine proceeds directly to step 100, and when a negative determination is made, that is, when it is determined that the braking operation by the driver is being performed, the routine proceeds to step 90.

In step 90, it is determined whether or not the vehicle speed V exceeds the larger predetermined value Vh shown in FIG. 4. If a negative determination is made, the process proceeds directly to step 110, where affirmative determination is made. When the determination is made, in step 100, the guard value Frgfm of the target regenerative braking force of the front wheels
ax is calculated from the map corresponding to the graph shown by the solid line in FIG.

In step 110, based on the vehicle speed V, the maximum regenerative braking force (guard value) of the regenerative braking device 40 for the rear wheels is obtained from a map similar to the map corresponding to the graph shown by the solid line in FIG. Frgrmax is calculated, and the target regenerative braking force Frgft for the front wheels and the target regenerative braking force Frg for the rear wheels are calculated.
rt is calculated according to the following equations 1 and 2, respectively. Note that MIN in the following equations 1 and 2 means that the smaller value in parentheses is selected. Frgft = MIN (Fbft, Frgfmax) (1) Frgrt = MIN (Fbrt, Frgrmax) (2)

In step 120, signals indicating the target regenerative braking forces Frgft and Frgrt are output to the engine control device 28. In step 130, the actual regenerative braking control performed by the regenerative braking control by the engine control device 28 will be described later. A signal indicating the regenerative braking force Frgfa of the front wheels and the actual regenerative braking force Frgra of the rear wheels is read from the engine control device 28.

In step 140, the front wheel target friction braking force Fbpft and the rear wheel target friction braking force Fbprt are calculated in accordance with the following equations 3 and 4, respectively. Fbpft = Fbft−Frgfa (3) Fbprt = Fbrt−Frgra (4)

In step 150, the target braking pressures Pbtfl and Pbtfr of the left and right front wheels are calculated based on the target friction braking force Fbpft of the front wheels, and the target braking pressures Pbtrl and Pbtrl of the left and right rear wheels are calculated based on the target friction braking force Fbprt of the rear wheels. Pbtrr is calculated, and the braking pressure of each wheel is controlled by pressure feedback so that the braking pressures Pi of the left and right front wheels and the left and right rear wheels become the corresponding target braking pressures Pbti, respectively.

As shown in FIG. 3, in step 22 of the target regenerative braking force calculation routine in step 20 described above, the depression stroke Sp is calculated from the map corresponding to the graph shown in FIG. Target deceleration Gs based on
t is calculated, and in step 24, the target deceleration Gpt based on the master cylinder pressure Pm is calculated from the map corresponding to the graph shown in FIG.

In step 26, the master cylinder pressure Pm is obtained from the map corresponding to the graph shown in FIG. 9 based on the final target deceleration Gt calculated in the previous cycle.
Α for target deceleration Gpt based on (0 ≦ α ≦ 1)
In step 28, the final target deceleration Gt is calculated as the weighted sum of the target deceleration Gpt and the target deceleration Gst according to the following equation 5. Gt = α · Gpt + (1−α) Gst (5)

In step 30, Kf and Kr are coefficients (positive constants) corresponding to the distribution ratio of the braking force to the front wheels and the rear wheels, respectively, and the target braking force Fbft for the front wheels and the target braking force Fbrt for the rear wheels are calculated. It is calculated according to the following equations 6 and 7, respectively. Fbft = Kf · Gt (6) Fbrt = Kr · Gt (7)

Next, a regenerative braking control routine by the engine device 28 in the illustrated embodiment will be described with reference to a flowchart shown in FIG. The control according to the flowchart shown in FIG. 5 is also started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals.

First, in step 210, signals indicating the target regenerative braking force Frgft of the front wheels and the target regenerative braking force Frgrt of the rear wheels are read from the braking control device 52. In step 220, the target regenerative braking force is read. The regenerative braking by the regenerative braking device 30 for the front wheels is executed with the upper limit of Frgft,
In step 230, the actual regenerative braking force Frgfa of the front wheels by the regenerative braking device 40 for the front wheels is calculated.

Similarly, in step 240, the regenerative braking by the rear wheel motor generator 42 is executed with the target regenerative braking force Frgrt as an upper limit, and in step 250, the rear wheel is generated by the rear wheel motor generator 42. The actual regenerative braking force Frgra is calculated, and in step 260, a signal indicating the actual regenerative braking force Frgfa of the front wheels and the actual regenerative braking force Frgra of the rear wheels is output to the braking control device 52. Return to

Next, an operation mode change permission control routine by the engine device 28 in the illustrated embodiment will be described with reference to a flowchart shown in FIG. The control according to the flowchart shown in FIG. 6 is repeatedly executed at predetermined time intervals by interruption.

First, in step 310, a signal indicating the vehicle speed V detected by the vehicle speed sensor 54 is read, and in step 320, a signal indicating the current operation mode of the hybrid engine 10 is sent to the braking control device. 5
2 and a determination is made in step 330 as to whether or not a request to change the operation mode of the hybrid engine 10 has been made. If a negative determination has been made, the process returns to step 310 and an affirmative determination has been made. Sometimes Step 3
Proceed to 40.

In step 340, it is determined whether or not the requested change of the operation mode is a change for changing the predetermined value from Vn to Vh. If a negative determination is made, the process directly proceeds to step 370. When the affirmative determination is made, a signal indicating that the normal regenerative braking is impossible and the target regenerative braking force is to be gradually reduced is output to the brake control device 52 in step 350.

In step 360, a signal indicating the target regenerative braking force Frgft of the front wheels is read, and
It is determined whether or not the target regenerative braking force Frgft of the front wheels has become zero, that is, whether or not the regenerative braking of the front wheels has been completed. If a negative determination has been made, the process returns to step 350, and an affirmative determination is made. When it is determined that the operation mode of the hybrid engine 10 has been changed in step 370, a signal is output to a hybrid engine operation mode control routine (not shown).

Thus, according to the illustrated embodiment, in step 20, the final target deceleration Gt as the driver's braking request amount is calculated based on the driver's braking operation amount, and the predetermined front and rear wheel braking force distribution ratio is calculated. The target braking force Fbft for the front wheels and the target braking force Fbrt for the rear wheels are calculated based on the final target deceleration Gt.

If the regenerative braking of the front wheels and the rear wheels is possible and the operation of the gasoline engine 12 can be stopped, an affirmative determination is made in steps 40 and 60, and the braking by the driver is performed. If the operation has not been performed, an affirmative determination is made in step 80, and in step 100, the guard value of the regenerative braking force of the front wheels is set to the standard value shown by the solid line in FIG. The guard value is maintained at the standard value even when the driver performs a braking operation. Accordingly, when regenerative braking is performed in such a situation, the guard control is performed with the small value Vn as a predetermined value regardless of whether or not the driver has performed a braking operation.

Next, the target braking forces Fbft and Fbrt for the front wheels and the rear wheels are achieved by regenerative braking as much as possible.
In step 110, the target regenerative braking force Frgft of the front wheel and the target regenerative braking force Frgrt of the rear wheel are respectively set to the target braking force F.
Calculated as the smaller of bft, Fbr and the maximum regenerative braking force Frgfmax, Frgrmax, and a signal indicating the target regenerative braking force is output to the engine control device 28 in step 120.

Further, in step 220 of the regenerative braking routine shown in FIG. 4, the motor generator 14 of the regenerative braking device 28 for the front wheels is controlled by the engine control device 26 with the target regenerative braking force Frgft for the front wheels as an upper limit. At 230, the actual regenerative braking force Frgfa by the regenerative braking device 38 for the front wheels based on the generated voltage and generated current of the motor generator 14
The motor generator 40 of the rear wheel regenerative braking device 38 is controlled by the engine control device 26 in step 240 with the target regenerative braking force Frgrt of the rear wheel as an upper limit, and in step 250 the motor generator An actual regenerative braking force Frgra by the regenerative braking device 38 for the rear wheels is calculated based on the generated voltage and the generated current of the rear wheel 40, and a signal indicating the actual regenerative braking force is output to the brake control device 52 in step 260.

Further, in step 130 of the braking force control routine shown in FIG. 2, the actual regenerative braking force Frgfa
Then, a signal indicating the actual regenerative braking force Frgra of the rear wheels is read. In step 140, the target frictional braking force Fbpft of the front wheels is increased from the target braking force Fbft by the actual regenerative braking force Fr.
gfa is subtracted, and the target friction braking force Fbprt of the rear wheel is calculated as a value obtained by subtracting the actual regenerative braking force Frgra from the target braking force Fbrt.
At 0, the target braking pressures Pbtfl and Pbtfr of the left and right front wheels are calculated based on the target friction braking force Fbpft of the front wheels, and the target braking pressures Pbtrl and Pbtrr of the left and right rear wheels are calculated based on the target friction braking force Fbprt of the rear wheels. At the same time, the braking pressure of each wheel is feedback-controlled so that the braking pressures Pi of the left and right front wheels and the left and right rear wheels become the corresponding target braking pressures Pbti.

Therefore, according to the illustrated embodiment, by transmitting information between the engine control device 28 and the braking control device 52, the braking force of the entire vehicle, that is, the friction braking of the front wheels and the rear wheels is performed. Since the sum of the braking force of the device and the braking force of the regenerative braking device is controlled to a value corresponding to the final target deceleration Gt, the braking force of the entire vehicle is reliably controlled according to the amount of braking required by the driver. can do.

The ratio of the sum of the braking force of the front and rear friction braking devices and the braking force of the regenerative braking device and the ratio of the total braking force of the rear wheel friction braking device and the braking force of the regenerative braking device are always predetermined. Of the front and rear wheel braking force distribution ratio Kf / Kr, the distribution ratio of the braking force of the front and rear wheels is reliably set to a predetermined value regardless of the ratio between the braking force by the friction braking device and the braking force by the regenerative braking device. It is possible to control the front and rear wheel braking force distribution ratio, which ensures that the vehicle stability decreases and the steering characteristics change due to the front and rear wheel braking force distribution ratio becoming a distribution ratio other than the predetermined distribution ratio. Can be prevented.

The target braking force Fbft of the front wheels is achieved by controlling the regenerative braking force and the friction braking force of the front wheels so that the braking force by the regenerative braking device for the front wheels is maximized.
The rear wheel target braking force Fbrt is also achieved by controlling the rear wheel regenerative braking force and the friction braking force so that the braking force of the rear wheel regenerative braking device is maximized. The regenerative braking force and the friction braking force can be controlled so as to maximize the regenerative efficiency of the entire vehicle while achieving the ratio.

Also, according to the illustrated embodiment, step 6
The predetermined value of the guard control of the target regenerative braking force in the range of 0 to 100 is changed according to the operation mode of the hybrid engine 10, and when the operation of the gasoline engine 12 cannot be stopped, the predetermined value is larger than the standard value Vn. Vh, the regenerative braking is incorrectly performed when the vehicle speed V falls below the predetermined value Vh in a situation where the operation of the gasoline engine 12 cannot be stopped. It is possible to reliably prevent the braking force of the vehicle from being incorrectly controlled.

Since the predetermined value is set to the standard value Vn when the operation of the gasoline engine 12 can be stopped, the predetermined value is fixedly set to a large value such as Vh regardless of the operation mode of the hybrid engine 10, for example. As compared with the case where the vehicle speed is low, accurate regenerative braking can be performed even in a region where the vehicle speed is low, and thereby the regenerative efficiency can be improved.

According to the illustrated embodiment, when a braking operation is performed by the driver and a negative determination is made in step 80, the operation mode of the hybrid engine 10 changes and the predetermined value changes from Vh to Vn. , The guard control is continued with Vh as a predetermined value, and the maximum regenerative braking force of the regenerative braking device 30 for the front wheels is calculated from a map corresponding to the graph shown by the broken line in FIG. Therefore, it is possible to reliably prevent a sudden increase in the regenerative braking force of the front wheels due to a change in the operation mode of the hybrid engine 10 and a sudden change in the deceleration of the vehicle due to this.

According to the illustrated embodiment, when the vehicle speed V becomes higher than Vh even in the situation where the guard control is continued with Vh as the predetermined value as described above, affirmative determination is made in step 90. The determination is performed, the predetermined value is changed to Vn, and the guard value Frgfmax of the regenerative braking device 30 for the front wheels is determined.
Is calculated from the map corresponding to the graph shown by the solid line in FIG. 4, so that the regenerative braking can be executed even in a region where the vehicle speed is relatively low. However, the regenerative efficiency can be increased as compared with the case where the predetermined value is maintained at the large value Vh.

Further, according to the illustrated embodiment, when the vehicle speed V becomes equal to or lower than the predetermined value Vn in a state where the regenerative braking is performed in the operation mode in which the operation of the gasoline engine 12 can be stopped, step 40 is executed. A negative determination is made in step 50, and in step 50, the target regenerative braking forces Frgft and Fgft
Operation of the hybrid engine 10 in which the predetermined value changes from Vn to Vh until the target regenerative braking force becomes 0 in steps 330 to 370 of the operation mode change permission control routine shown in FIG. Since the change of the mode is prohibited and the change of the operation mode is permitted when the target regenerative braking force becomes 0, the regenerative braking force is rapidly decreased with the change of the operation mode, and this is caused by this. A sudden change in the deceleration of the vehicle can be reliably prevented.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described embodiment, the target regenerative braking force and the actual regenerative braking force are communicated between the engine control device 28 and the braking control device 52. A target regenerative braking torque is calculated based on the regenerative braking force, and a signal indicating the target regenerative braking torque is communicated from the brake control device 52 to the engine control device 28,
The regenerative braking is controlled by the engine control device 28 with the target regenerative braking torque as an upper limit, and a signal indicating the actual regenerative braking torque is conversely transmitted from the engine control device 28 to the braking control device 5.
2 may be modified to calculate the actual regenerative braking force based on the actual regenerative braking torque.

In the above-described embodiment, the predetermined value is set to the standard value Vn according to the operation mode of the hybrid engine.
And the large value Vh, but the predetermined value may be modified to be changed in three or more stages according to the operation mode of the hybrid engine.

In the above-described embodiment, the target deceleration Gt of the vehicle is calculated based on the depression stroke Sp of the brake pedal 32 and the master cylinder pressure Pm, and the target braking force Fbft of the front wheels and the rear braking force Fbft are calculated based on the target deceleration. Although the target braking force Fbrt of the wheel is calculated, the target braking force of the front wheel and the rear wheel may be calculated based on the depression stroke Sp or the master cylinder pressure Pm.

In the above-described embodiment, the front and rear wheel distribution ratio Kf / Kr of the braking force is constant irrespective of the magnitude of the target braking force, but is shown by a broken line in FIG. 10, for example. Thus, the correction may be made such that the braking force distribution ratio of the rear wheels to the front wheels decreases as the target braking force increases.

In the above-described embodiment, the driving means for driving the vehicle includes the gasoline engine 12 and the motor generator 1.
4, the internal combustion engine of the hybrid engine may be another internal combustion engine such as a diesel engine, and regenerative braking is performed only on front wheels or rear wheels driven by the hybrid engine. May be modified.

In the above embodiment, the vehicle is a front wheel drive vehicle. However, the vehicle to which the present invention is applied may be a rear wheel drive vehicle or a four wheel drive vehicle. The generator 40 operates only as a generator for regenerative braking, but may be modified to function as an auxiliary drive source for driving the rear wheels as needed, for example.

[0080]

As is apparent from the above description, according to the configuration of the first aspect of the present invention, the predetermined value is optimally set according to the operation mode of the hybrid engine, whereby the guard control is performed for the hybrid engine. The regenerative braking force can be optimally executed in accordance with the operation mode. In particular, according to the configuration of the second embodiment, the regenerative braking force suddenly increases with the change in the operation mode, and the sudden change in the deceleration of the vehicle caused by the change. Can be reliably prevented.

According to the third aspect of the present invention, in a situation where the guard control is continued at the large predetermined value, the guard control is performed at the large predetermined value even when the vehicle speed becomes higher than the large predetermined value. A hybrid in which the predetermined value changes to a large value until the regenerative braking force becomes 0, according to the configuration of the fourth aspect, wherein the regenerative efficiency can be improved as compared with the case where it is continued, and the fuel efficiency of the vehicle can be improved. Since the change in the operation mode of the engine is prohibited, it is possible to reliably prevent the regenerative braking force from suddenly decreasing due to the change in the operation mode and the sudden change in the deceleration of the vehicle caused by the sudden decrease.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a braking force control device according to the present invention applied to a front wheel drive type vehicle equipped with a hybrid engine.

FIG. 2 is a flowchart showing a main routine of braking force control by a braking control device in the illustrated embodiment.

FIG. 3 is a flowchart showing a subroutine for calculating a target braking force in step 20.

FIG. 4 is a graph showing a relationship between a vehicle speed V and a target regenerative braking force and a guard value Frgfmax of a regenerative braking force of a front wheel.

FIG. 5 is a flowchart showing a regenerative braking control routine by the engine control device in the illustrated embodiment.

FIG. 6 is a flowchart illustrating an operation mode change permission control routine of a hybrid engine in the illustrated embodiment.

FIG. 7 is a graph showing a relationship between a depression stroke Sp of a brake pedal and a target deceleration Gst.

FIG. 8 is a graph showing a relationship between a master cylinder pressure Pm and a target deceleration Gpt.

FIG. 9 is a graph showing a relationship between a final target deceleration Gt calculated last time and a weight α for the target deceleration Gpt.

FIG. 10 is a graph showing a relationship between a target braking force Fbft of a front wheel and a target braking force Fbrt of a rear wheel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Hybrid engine 12 ... Gasoline engine 14 ... Motor generator 18 ... Continuously variable transmission 28 ... Engine control device 30 ... Regenerative braking device for front wheels 32 ... Brake pedal 40 ... Regenerative braking device for rear wheels 42 ... Motor generator 44 ... Friction braking device 50 Master cylinder 52 Braking control device 54 Vehicle speed sensor 56 Voltage sensor 58 Stroke sensor 60 Pressure sensor

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5H115 PA01 PA08 PC06 PG04 PI16 PI22 PI29 PO02 PO06 PO17 PU01 PU22 PU24 PU25 QE02 QE03 QE10 QI04 QI07 QI09 QI12 QN03 RB08 SE04 SE05 TI05 TO12 TO13 TO21 TO23 TO26 TO30

Claims (4)

[Claims] 1. A braking force control device for a vehicle equipped with a hybrid engine including a regenerative braking motor generator,
In a vehicle braking force control device for performing a guard control for stopping regenerative braking when a vehicle speed is equal to or lower than a predetermined value, the predetermined value is changed according to an operation mode of the hybrid engine. Control device. 2. When a braking operation is performed by a driver, even when the operation mode of the hybrid engine changes and the predetermined value changes to a small value, a large value corresponding to the operation mode before the change is obtained. The braking force control device for a vehicle according to claim 1, wherein the guard control is continued at a predetermined value. 3. Even when the guard control is continued at the large predetermined value, when the vehicle speed becomes higher than the large predetermined value, the predetermined value is changed to a small predetermined value corresponding to the current driving mode. 3. The method according to claim 2, wherein the change is performed.
A braking force control device for a vehicle according to Claim 1. 4. When the vehicle speed falls below a predetermined value in a situation where regenerative braking is performed, the regenerative braking force is gradually reduced, and the predetermined value changes to a large value until the regenerative braking force becomes zero. 2. The vehicle braking force control device according to claim 1, wherein a change in the operation mode of the hybrid engine is prohibited.