JPH07203602A - Braking equipment of electric vehicle - Google Patents

Abstract

PURPOSE:To collect energy efficiently by executing regenerative braking suitably and also to attain a balance with a braking force of non-regenerative wheels in an electric vehicle. CONSTITUTION:A hydraulic valve 70 is provided for a hydraulic system from a brake master cylinder 54. A charged state of a battery 48 is detected by battery ECU 94 and a maximum regenerative braking force which can be given to front wheels 42 and 44 by regeneration is computed. In the case when a requested braking force by treading of a brake pedal 52 is less than the maximum regenerative braking force, the braking force is supplied by the regeneration. In the case when the requested braking force becomes the maximum regenerative braking force or more, the hydraulic valve 70 is controlled to distribute an oil pressure of the brake master cylinder 54 to front and rear wheels and the distribution of the braking force to the front and rear wheels is controlled properly. For the proper distribution of the braking force, a control for making a frictional braking force of rear wheels 72 and 74 rise sharply or delaying a rise of the frictional braking force of the front wheels 42 and 44 is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device and a braking method for an electric vehicle, and more particularly to a braking device for an electric vehicle that uses both braking utilizing regeneration by an on-vehicle motor and braking by friction.

[0002]

2. Description of the Related Art Conventionally, as a braking device for an electric vehicle of this type, as described in, for example, Japanese Patent Laid-Open No. 64-43001, when the brake pedal is operated, the main electric vehicle is initially used. A configuration is used in which braking is performed using regeneration by a motor, and when braking force due to regeneration is insufficient for braking, friction braking force using hydraulic pressure generated by stepping on a brake pedal is used (for example, Japanese Patent Laid-Open No. Hei 2). -120165 gazette).

At the initial stage of braking, the required braking force required can be applied to the wheels by braking by regenerative braking. Therefore, only the regenerative braking is used to enhance the energy regenerating efficiency, and after the braking by regenerative braking becomes insufficient. For the first time, the friction braking force is used. By the way, since the maximum braking force due to such regeneration varies depending on the temperature of the battery and how much the battery is discharged, etc., simply combining braking by regeneration and braking by friction will produce satisfactory braking performance. In some cases, it was not possible, and attempts were made to improve this point. Regarding the problem and its improvement,
It will be described with reference to the drawings.

FIG. 21 shows a state of a braking force in the case where braking by regeneration and braking by friction (hydraulic brake) are combined. The braking force due to regeneration can be adjusted by controlling the electric power that is regenerated, and up to the maximum braking force E, a master cylinder (M / C) generated by operating the brake pedal.
It is controlled so as to be proportional to the oil pressure. As shown in FIG. 21 (A), since braking by regeneration has an upper limit in energy recovery, when the maximum braking force E is reached, no further braking force can be obtained. The oil pressure of M / C at this time is P
When the hydraulic pressure of M / C is higher than 0, as shown in FIG.
As shown in (B), a braking force due to friction is applied. In this case, the total braking force obtained by combining the two is shown in FIG.
As shown in (C), it is proportional to the hydraulic pressure of the master cylinder (M / C) by the operation of the brake pedal, and the driver's braking feeling does not feel any discomfort.

However, for example, when the battery is close to full charge, the maximum braking force due to regeneration is reduced. Therefore, when the maximum braking force due to regeneration is reduced to E ', the total braking force obtained by combining the regenerative brake and the hydraulic brake is M / C, as shown in FIG.
There was a case where the braking force was discontinuous without being proportional to the hydraulic pressure of the vehicle and the brake feeling of the driver was impaired.
In this case, the braking effect is naturally weakened and the braking distance becomes long. In order to avoid such a problem, a configuration has been proposed in which the maximum braking force by regeneration is obtained, and the hydraulic brake is operated when the required braking force exceeds the maximum regenerative braking force (for example, JP-A-5-161210). ).

[0006]

However, as shown in FIG.
Even when the characteristic of (C) is obtained, considering the state where the braking by the hydraulic brake has started to work, the regenerative brake is only for the drive wheels (regenerative wheels), and the hydraulic brake is for the drive wheels and the idle wheels (non Since it acts equally to the regenerative wheels), the ratio of the braking force on the driving wheel side becomes high, and there is a problem that the balance of the braking forces of both wheels is largely separated from the ideal distribution of the braking force. Although it is possible to deal with this problem by applying hydraulic braking to the non-regenerative wheels from the beginning of braking, this will reduce the energy recovery efficiency.

The braking system for an electric vehicle according to the present invention aims to solve these problems, efficiently perform regenerative braking, improve energy recovery efficiency, and realize appropriate braking force distribution. It was made and adopted the following composition.

[0008]

A first braking system for an electric vehicle of the present invention is, as illustrated in FIG. 1, a braking system for an electric vehicle that applies a braking force to each wheel of a vehicle based on a required braking force. In addition, regenerative braking force applying means M1 capable of applying a regenerative braking force to at least one of the wheels by using the regeneration by the on-vehicle motor MM, the regenerative wheel W1 for applying the regenerative braking, and the regenerative braking is not applied. For non-regenerative wheel W2,
If the required braking force is less than the maximum braking force that can be applied by the regenerative braking force applying means M1, the friction braking force applying means M2 that can independently apply the braking force by friction and the regenerative braking force applying means M1 can be used. Regenerative wheel braking means M3 for braking the regenerative wheel W1 and, when the required braking force exceeds the maximum braking force, the regenerative wheel W1 and the non-regenerative wheel W2 in consideration of the braking force due to the regeneration. Braking force distribution ratio determining means M4 for determining the distribution ratio of the braking force of M.
The gist is that the regenerative wheel W1 and the non-regenerative wheel W2 are provided with a braking force control means M5 for applying a braking force due to friction to the friction braking force application means M2 based on the determined distribution ratio.

Further, the braking device for the second electric vehicle according to the present invention, which applies the braking force to each wheel of the vehicle based on the required braking force, regenerates at least one of the wheels using regeneration by the motor MM mounted on the vehicle. Regenerative braking force applying means M1 capable of applying power, frictional braking force applying means capable of independently applying braking force by friction to the regenerative wheel W1 that applies the braking by the regeneration and the non-regenerative wheel W2 that does not apply the braking by the regeneration. M2 and regenerative wheel braking means M3 for braking the regenerative wheel W1 by the regenerative braking force applying means M1 when the required braking force is less than the maximum braking force that can be applied by the regenerative braking force applying means M1.
When the required braking force exceeds the maximum braking force, the friction braking force imparting means M2 imparts the insufficient braking force to the non-regenerative wheel W2 as a braking force by friction, and the braking force is reduced. A braking force application delay means M10 for applying a braking force due to friction to the regenerative wheel W1 after the application of power.
(Shown by the one-dot chain line in FIG. 1).

[0010]

In the braking device for the first electric vehicle of the present invention configured as described above, when the required braking force is less than the maximum braking force that can be given by the regenerative braking force giving means M1, the regenerative wheel braking means is provided. M3 brakes the regenerative wheel W1 by the regenerative braking force applying means M1 capable of applying the regenerative braking force to at least one of the wheels using the regeneration by the motor MM mounted on the vehicle.
On the other hand, when the required braking force exceeds the maximum braking force due to regeneration, the braking force distribution ratio determining means M4 considers the braking force due to regeneration and then determines the braking force of the regenerative wheel W1 and the non-regenerative wheel W2. The distribution ratio is decided close to the ideal distribution. The braking force control means M5 applies the braking force by friction to the regenerative wheels W1 and the non-regenerative wheels W2 by the friction braking force applying means M2 based on the distribution ratio thus determined.

Here, as the braking force distribution ratio determining means M4, when the required braking force exceeds the maximum braking force, the shortage of the braking force is used as the braking force due to friction between the regenerative wheel W1 and the non-regenerative wheel W2. Regenerative wheel W1 and non-regenerative wheel W
Until the distribution ratio of the braking force to 2 reaches a predetermined ratio, the distribution ratio is determined by giving priority to the non-regenerative wheel W2, and after the distribution ratio of the braking force reaches the predetermined ratio, the distribution ratio is determined according to the ideal distribution. May be determined.

The second electric vehicle braking device of the present invention is the first braking device for braking the regenerative wheel W1 from the regenerative wheel braking means M3 when the required braking force is less than the maximum braking force by regeneration. Although it is the same as the braking device of the invention, when the required braking force exceeds the maximum braking force, the braking force application delay means M10 causes the friction braking force application means M2 to apply the insufficient braking force to the regenerative wheel W1. The braking force is applied as a frictional force, and the braking force by friction is also applied to the regenerative wheel W1 after the application of the braking force. Therefore, the non-regenerative wheel W2
The braking force on the side increases preferentially as compared with the regenerative wheel W1, and the imbalance in the distribution of the braking force is improved.

Here, various braking force application delay means can be considered. For example, non-regenerative wheel W2
The braking force due to friction is applied to the regenerative wheel W1 after the braking force due to friction to the predetermined value or more, or the required braking force is equal to or greater than the maximum braking force that can be applied by the regeneration, and the regeneration is performed. The braking force due to friction is also applied to the wheel W1, or the ratio between the maximum braking force applied to the regenerative wheel W1 and the braking force due to friction to the non-regenerative wheel W2 becomes the ideal distribution ratio, and then to the regenerative wheel W1. It is possible to apply a braking force due to friction.

In the first and second aspects of the present invention, the regenerative braking force applying means M1 means that the motor MM that drives the regenerative wheel W1 during operation and other on-vehicle motors MM are used as a generator during braking. Is a means for applying a braking force to the regenerative wheel W1 by recovering energy.
Further, the frictional braking force applying means M2 is a means for applying a braking force due to friction to the regenerative wheel W1 and the non-regenerative wheel W2, and is a braking means that does not directly recover energy.
As such a means, a friction brake such as a disc brake which operates by receiving the transmission of the hydraulic pressure generated by the operation of the brake pedal is generally used, but a structure of a power brake for increasing the hydraulic pressure is additionally provided. Alternatively, a transmission means other than hydraulic pressure may be used. The braking by friction is a concept in a broad sense, and it is needless to say that it is included as long as braking is applied by mechanical means.

Regenerative wheel braking means M in the first braking device
3, braking force distribution ratio determination means M4, braking force control means M5 or braking force application delay means M1 in the second braking device
Each 0 may be realized by a discrete circuit configuration, but may be realized by software by an arithmetic logic operation circuit such as a one-chip microcomputer. In addition, a circuit for controlling the drive and power generation of the motor MM,
The circuit for controlling the battery, the circuit for controlling regenerative braking, etc. may be realized by separate computers and their software, or all or complex processing may be executed by the same computer. Absent.

[0016]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 2 is a schematic configuration diagram of a braking device 40 for an electric vehicle as a first embodiment. The electric vehicle of the embodiment is
It is a front-wheel drive vehicle (FF vehicle), and motors 46 for driving the front wheels 42, 44 are coupled to the front wheels 42, 44 through gears. Further, this electric vehicle is equipped with a large-scale battery 48, and travels via the inverter 50 using the electric energy charged in the battery 48 as the only power source.

A hydraulic system that controls the braking of the electric vehicle will be described. In the braking device 40 of the embodiment, as shown in FIG. 2, a brake master cylinder 54 that generates hydraulic pressure for braking by operating the brake pedal 52, a reservoir 56 of the hydraulic pressure, and a feeling of depression of the brake pedal 52. A brake simulator 58 for adjusting the vehicle to a normal brake system, a hydraulic sensor 60 for detecting the hydraulic pressure P generated by the master cylinder 54, front wheel cylinders 62, 64 for applying a braking force due to friction to the front wheels 42, 44, a front wheel A hydraulic valve 70 provided in a hydraulic pipe 68 between the cylinders 62, 64 and the master cylinder 54, rear wheel cylinders 82, 84 for applying a braking force by friction to rear wheels 72, 74, rear wheel cylinders 82, 84 Installed in series in the hydraulic pipe 78 between the master cylinder 54 and Hydraulic valve 71 and a pressure valve (so-called P valve) 80 and the like are provided with.

The brake simulator 58 is used to improve the driver's brake feeling.
As will be described later, when braking is performed by regeneration using the motor 46 and the hydraulic pressure generated in the brake master cylinder 54 is not used for braking the front wheels 42, 44, the depression amount of the brake pedal 52 becomes the braking force. The phenomenon that it is not proportional occurs. Brake simulator 58
The volume of the brake master cylinder 54 changes in response to the hydraulic pressure generated in the brake master cylinder 54. Therefore, even when the hydraulic pressure of the brake master cylinder 54 is not used for braking the front wheels, the stepping margin of the brake pedal 52 is ensured to maintain the hydraulic pressure. It realizes the same brake feeling as when the braking used is performed.

The structure and function of the hydraulic valve 70 will be described later, but if this valve is a normal pressure valve 80,
The braking force applied to the front wheels 42, 44 and the rear wheels 72, 74 is proportional to the pressure generated in the brake master cylinder 54 according to the depression of the brake pedal 52. In the example,
The front wheels 42 and 44, which are the driving wheels, use the braking force of the regenerative brake (the brake that uses the motor 46 as a generator), and therefore the hydraulic valve 70 is used.
The braking force due to the friction applied to 2, 44 is controlled. Further, in order to make the distribution ratio of the braking force appropriate, the rear wheels 7
With respect to Nos. 2 and 74, another hydraulic valve 71 is used to control the braking force due to the friction applied to the rear wheels 72 and 74.

The braking device 40 of the embodiment shown in FIG.
A regenerative ECU 90 that controls regeneration by the motor 46, a motor ECU 92 that controls the drive of the motor 46 by controlling the inverter 50, a battery ECU 94 that manages the state of charge of the battery 48, and the like are mounted. Each ECU 9
CPUs 90a, 9 that control the entire control are provided at 0, 92, 94.
2a, 94a, ROM 90 storing a control program
b, 92b, 94b, RAM 90 as a work area
c, 92c, 94c, and input / output I / Fs 90d, 92d, 94d that control the interface of external input / output.

In addition to the detection signal from the hydraulic pressure sensor 60, the regenerative ECU 90 receives the driving information from the motor ECU 92 and the information about the charge state from the battery ECU 94.
It is input through the input / output I / F 90d. Regeneration EC
The U90 can know whether or not the brake pedal 52 has been operated by the hydraulic pressure detected by the hydraulic sensor 60, and in this sense, the hydraulic sensor 60 is equivalent to a brake switch of a normal brake system. Further, the regenerative ECU 90 drives the hydraulic valve 70 via the input / output I / F 90d.

The motor ECU 92 receives the oil pressure signal detected by the oil pressure sensor 60 via the regenerative ECU 90 and can know the oil pressure of the master cylinder 54. The motor ECU 92 exchanges signals with the inverter 50 to control the drive torque and the regenerative amount (regenerative torque) of the motor 46.

The battery ECU 94 is an input / output I / F 94.
connected to the battery 48 via the d
Manage 8 states. Information such as the amount of charge of the battery 48 is required to grasp the maximum amount of regeneration and the like.

Next, the structure and function of the hydraulic valves 70 and 71 will be described. FIG. 3 is an explanatory diagram showing a detailed configuration of the hydraulic valve 70. This hydraulic valve 70 is connected to a master cylinder 54 and a hydraulic pipe 68, and is connected to a master cylinder port 100, a sub port 102, and wheel cylinders 62 and 64.
04. The sub-port 102 and the wheel cylinder port 104 are both connected to the wheel cylinders 62, 64.
When the hydraulic cylinder is connected to the master cylinder 54, two poppet valves are connected in parallel between the master cylinder 54 and the wheel cylinders 62 and 64 (see FIG. 2). One of the poppet valves is a pressure-increasing side poppet valve 110 capable of controlling the pressure at which pressure increase is started, and the other is a pressure-decreasing side poppet valve 112 having a fixed operating pressure. Both of them have opposite directions of reverse hydraulic pressure.

The pressure increasing side poppet valve 110 is provided with a ball 114.
The shaft 116 is pressed against the valve seat to maintain the closed state. When the solenoid coil 118 incorporated in the main body is energized, the plunger 119 of the solenoid exerts a force for pressing the ball 114 toward the valve seat via the shaft 116. Therefore, the solenoid coil 1
By controlling the amount of electricity supplied to 18, it is possible to freely control the force pressing the ball 114 against the valve seat. The pressure reducing side poppet valve 112 provided in the flow path 117 branched from the master cylinder port 100 is operated by the hydraulic pressure generated by the master cylinder 54 (hereinafter, referred to as master cylinder hydraulic pressure, and abbreviated as M / C hydraulic pressure as necessary). , Ball 120
Is pressed against the valve seat and is closed, so M /
The pressure increasing side poppet valve 110 is also kept closed until the force acting on the ball 114 by the C hydraulic pressure exceeds the suction force by the solenoid coil 118.

The operation principle of the pressure increasing side poppet valve 110 of the hydraulic valve 70 having the above-mentioned structure is schematically shown as follows.
It is FIG. As shown, the booster side poppet valve 110
The hydraulic pressure PM / C of the master cylinder 54 is applied to the ball 114 of the master cylinder 54 in the opening direction, while the shaft 116
A force F is applied in the opposite direction via. Ball 1
Let A be the inner cross-sectional area of the outer peripheral line that is in contact with the valve seat when 14 is fully closed. If F> A · PM / C, this valve is kept fully closed. .

By depressing the brake pedal 52, the M / C oil pressure generated by the master cylinder 54 rises, and when F ≦ A / PM / C, the ball 114 gradually moves to the open side and the hydraulic valve 70 From the above, the pressure obtained by subtracting the pressure corresponding to the force F from the M / C oil pressure of the master cylinder 54 is applied to the front wheel cylinders 62 and 64. As will be described later in detail, in practice, as shown in FIG. 5, the energization of the solenoid coil 118 is controlled so that F = A · P0 with respect to the pressure P0 corresponding to the maximum braking energy E that can be generated by regeneration. Has been done.

When the brake pedal 52 is returned after the M / C hydraulic pressure exceeds the predetermined pressure P0 by strongly depressing the brake pedal 52, the pressure on the front wheel cylinders 62, 64 side is on the brake master cylinder 54 side. Since the pressure is higher than the pressure, the pressure increasing side poppet valve 110 is closed and the pressure reducing side poppet valve 112 is opened. Therefore, the wheel cylinder 62,
The hydraulic pressure of 64, and thus the braking force, decreases in accordance with the operation of the brake pedal 52.

On the other hand, the hydraulic valve 71 provided in the hydraulic system on the side of the rear wheels 72, 74 has the same structure as the hydraulic valve 70 for the front wheels 42, 44, but the control from the regenerative ECU 90 is different, so that The starting pressure is different from that of the hydraulic valve 70. Further, a pressure valve 80 is provided on the downstream side of the hydraulic valve 71, and the pressure applied to the wheel cylinder after the M / C hydraulic pressure exceeds the starting pressure is set to a predetermined value with respect to the M / C hydraulic pressure. Percentage. When the hydraulic valve 71 is controlled to open at the same pressure as the hydraulic valve 70, the rear wheel cylinders 82, 84 that determine the braking force of the rear wheels 72, 74 have hydraulic valves 71 and pressure valves as shown in FIG. 80, M / C oil pressure is P
After reaching 0, the hydraulic pressure is increased at a predetermined rate.

Next, the control of the braking force in the first embodiment of the present invention will be described with reference to the flowchart of FIG. Note that FIG. 6 does not show the processing of the regenerative ECU 90 alone, but rather the regenerative ECU 90 and the motor ECU 92.
Shows the control realized by being integrated with the hydraulic valves 70 and 71.

The braking device 40 first determines whether or not the M / C oil pressure is 0 (step S180), and the M / C is determined.
When the hydraulic pressure has a value of 0, processing for turning off the regenerative brake is performed (step S181). Actually, the regenerative ECU
In response to the command from 90, the motor ECU 92 stops the regeneration of electric power by the motor 46 via the inverter 50.

On the other hand, when the M / C oil pressure is not 0,
The brake pedal 52 is operated, it is determined that braking is requested, and processing for turning on the regenerative brake is performed (step S182). That is, the motor ECU 92 controls the regeneration of electric power via the inverter 50,
The battery 48 is charged with the electric power generated by 6. Further, it is judged whether or not the M / C oil pressure is larger than a predetermined value PR (step S183).

Here, the predetermined value PR is a value corresponding to the M / C oil pressure of the brake master cylinder 54 corresponding to the maximum braking force E by regeneration as shown in FIG. The braking force by regeneration is the braking force applied to the front wheels 42, 44 by operating the motor 46 as a generator, and is proportional to the electric power generated. However, since the electric power to be generated has an upper limit on the system, when the motor ECU 92 controls the inverter 50 to gradually increase the electric power generation amount, the electric power generation amount reaches a peak at the predetermined electric power generation amount. This is the value E shown as the maximum value of the braking energy in FIG. 7. This maximum power that can be generated also depends on the state of charge of the battery 48 connected via the inverter 50. For example,
If the battery 48 is in a fully charged state, the battery 48 cannot be accepted even if a large amount of power is generated, so the need for power generation is reduced, and braking by regeneration is inevitable. When a braking force greater than the braking force that can be applied by regeneration is required, it is necessary to brake each wheel using the braking hydraulic pressure generated by the brake master cylinder 54. Therefore,
The maximum braking force E calculated from the state of the battery 48 is compared.

When the M / C oil pressure is larger than the predetermined value PR, the processing for opening the hydraulic valve 71 installed in the hydraulic system for the rear wheels 72, 74 is performed (step S184). That is, the energization amount to the solenoid coil 118 is set so as to prevent the frictional braking force from acting up to the braking force corresponding to the maximum braking force E. As a result, when the brake pedal 52 is depressed and the hydraulic pressure in the brake master cylinder 54 becomes greater than the predetermined value PR, the rear wheels 72,
Hydraulic pressure for braking is supplied to the rear wheel cylinders 82 and 84 of 74. At this point, hydraulic pressure is not yet supplied to the front wheel cylinders 62 and 64 of the front wheels 42 and 44.

Therefore, it is next judged whether or not the M / C oil pressure has become larger than the second predetermined value Pf which is larger than the predetermined value PR (step S185), and the brake pedal 5 is operated.
When 2 is further depressed and the M / C oil pressure exceeds the second predetermined value Pf, the processing for opening the hydraulic valve 70 installed in the hydraulic system on the side of the front wheels 42, 44 is performed (step S1).
86). As shown in FIG. 7, the second predetermined value Pf is a value set such that the hydraulic braking of the front wheels 42, 44 is started later than the hydraulic braking of the rear wheels 72, 74. Therefore, the solenoid coil 1 of the hydraulic valve 70 is opened so that the hydraulic valve 70 is opened above this hydraulic pressure.
The power supply to 18 is controlled. As a result, the brake pedal 52 is depressed and the brake master cylinder 54
When the hydraulic pressure of is greater than the predetermined value Pf, the hydraulic pressure for braking is supplied to the front wheel cylinders 62 and 64 of the front wheels 42 and 44 for the first time. At this point, the rear wheels 7
The hydraulic pressure has already been supplied to the rear wheel cylinders 82 and 84 of 2,74, and the total braking force in the vehicle is "the braking force by regeneration" + "the friction braking force by the hydraulic pressure to the rear wheels 72,74" + " The frictional braking force by the hydraulic pressure is applied to the front wheels 42 and 44. "

In the braking device 160 of the first embodiment constructed as described above, when the braking force required by the brake pedal 52 exceeds the maximum braking force E obtained by regeneration, first, the rear wheels which are non-driving wheels. Since the braking force due to friction is applied to the 72 and 74 sides by utilizing the M / C hydraulic pressure, the advantage that the balance of the braking force between the front wheels 42 and 44 and the rear wheels 72 and 74, which are the driving wheels, becomes good can be obtained. . As a result, it is possible to obtain an effect that the slip is less likely to occur and the braking distance is shortened. Further, in this embodiment, regeneration is not prohibited even if there is a demand for braking, and if the braking force is below a predetermined value (M / C oil pressure ≤ PR), only braking by regeneration is used. Therefore, there is no waste of energy. Therefore, the one-charge mileage is also improved.

Next, a second embodiment of the present invention will be described. This embodiment is realized by the same hardware configuration as that of the first embodiment, and like the first embodiment, the front wheels 4 are
It is intended to optimize the proportional distribution of the braking force between the wheels 2, 44 and the rear wheels 72, 74. The braking device 40 of the second embodiment is shown in FIG.
The processing routine shown in is executed. This process is a regenerative EC
It is executed by U90.

When this processing is started, it is determined whether or not the brake switch is turned on based on the M / C oil pressure detected by the oil pressure sensor 60 (step S2).
00). When the brake switch is off, it is not necessary to control the braking force. Therefore, the initial value Gint of the braking force due to the friction of the rear wheels 72 and 74 is set (step S202), and nothing is done. Not
The process ends.

On the other hand, if it is determined that the brake switch is on, a process of reading the charge state of the battery 48 is performed (step S204), and the front wheels 42, 44 which are the drive wheels of the vehicle are determined from the charge state of the battery 48. The maximum regenerative braking force Gmax is calculated (step S2).
06). The maximum regenerative braking force Gmax corresponds to the maximum value of braking that the front wheels 42 and 44, which are drive wheels, can perform by regeneration, and is a value determined by the state of charge of the battery 48 and other factors. In other words, it can be said that the braking force equal to or greater than the maximum regenerative braking force Gmax cannot be applied to the front wheels 42 and 44, which are the driving wheels, by regeneration. Next, a process of reading the M / C oil pressure P of the brake master cylinder 54 via the motor ECU 92 is performed (step S208), and this M / C oil pressure P is read.
Based on the above, processing for calculating the total braking force is performed (step S210). The total system power is calculated according to the straight line J1 in FIG. That is, the braking force proportional to the hydraulic pressure generated in the brake master cylinder 54 according to the depression of the brake pedal 52 is obtained. The M / C hydraulic pressure is hereinafter referred to as a brake pedal force, which means a pressure corresponding to the operation of the brake pedal 52.

Next, it is judged whether or not the total braking force thus obtained is equal to or larger than the maximum regenerative braking force Gmax previously obtained (step S206) (step S212). If the total system power is not more than the maximum regenerative braking force Gmax, the motor E
Sending a control signal to the CU92 to regenerate braking torque TB
The inverter 50 is controlled via the motor ECU 92 so that the total braking force is calculated in step S210 (step S214). If the entire system power is in time for braking by regeneration, the friction braking force by hydraulic pressure is not necessary, so the front wheel cylinders 62, 62 of the front wheels 42, 44,
Hydraulic valve 70 so that M / C oil pressure is not supplied to 64
The rear wheel cylinders 82, 84 of the rear wheels 72, 74
The hydraulic valves 71 are kept closed (step S216) so that the M / C hydraulic pressure is not supplied to step S216. In order to easily distinguish between the two valves, the hydraulic valve 70 will be referred to as an Fr brake hydraulic valve and the hydraulic valve 71 will be referred to as an Rr brake hydraulic valve hereinafter.

On the other hand, if it is determined in step S212 that the total braking force is equal to or greater than the maximum regenerative braking force Gmax, the regenerative braking torque TB is first controlled to the maximum regenerative braking force Gmax (step S220), and the regenerative braking force Gmax is controlled. The maximum braking force obtained is applied to the front wheels 42, 44. After that, a process for setting the hydraulic braking force of the rear wheels 72 and 74 (hereinafter, referred to as Rr hydraulic braking force), which are idle wheels, to an initial value Gint is performed to supplement the insufficient braking force with hydraulic pressure (step S222). ). Then, the Rr hydraulic braking force is set to a value obtained by adding a frictional force corresponding to the stepping force of the brake pedal 52 to the initial value Gint (step S224).
The frictional force corresponding to the pedal effort of the brake pedal 52 is a value that is predetermined so as to increase in proportion to the brake pedal effort, as indicated by the straight line J2 in FIG. As a result, the rear wheels 7
The braking force applied to Nos. 2 and 74 is the maximum regenerative braking force Gmax as shown in FIG. 9 as “Rr friction”.
When it exceeds, the initial value is set to Gint, and thereafter, it increases in proportion to the brake pedal force (M / C oil pressure).

Next, a process of setting the hydraulic braking force on the front wheels 42, 44 (hereinafter referred to as Fr hydraulic braking force) as a friction force according to the brake pedal force is performed (step S22).
6). That is, the Fr hydraulic braking force is shown in FIG.
As indicated by (straight line J3), when the total braking force exceeds the maximum regenerative braking force Gmax, the braking force is determined to increase in proportion to the brake pedal force. Rear wheels 72, 74,
As described above, after setting the hydraulic braking forces for the front wheels 42, 44, the braking forces of the front wheels 42, 44 and the rear wheels 72, 74 are set to the Rr hydraulic braking force and the Fr hydraulic braking force, respectively. The hydraulic valves 70 and 71 are controlled (step S228). After that, the process goes to "END", and this processing routine ends.

In the above description, in order to facilitate understanding, the hydraulic valve 70 and the hydraulic valve 71 are directly controlled in step S228 to control the Rr and Fr braking forces, but in reality, the hydraulic valve 70 is used. , The current supplied to the solenoid coil 118 of the hydraulic valve 71 is set to the maximum regenerative braking force G
The brake pedal force at which the Fr hydraulic braking force and the Rr hydraulic braking force rise is determined only by determining according to max.
Further, the rate of increase of the hydraulic braking force with respect to the brake pedal force (the inclination of the straight lines J2 and J3) is determined by the pressure loss of the hydraulic valves 70 and 71 and the set value of the pressure valve 80. Therefore, the rate of increase of the hydraulic braking force with respect to the brake pedal force is predetermined, and the actual control performed during braking sets the initial value of the Rr hydraulic braking force in step S202 (that is, the urging force of the solenoid coil 118). Is reduced by the hydraulic pressure corresponding to the initial value Gint),
It is only necessary to determine the energization current of the solenoid coil 118 of the hydraulic valve 70 and the hydraulic valve 71 according to the maximum regenerative braking force Gmax obtained in step S206. This relationship is the same in the other embodiments described below.

In the present embodiment described above, the total braking force (the required braking force required in proportion to the M / C hydraulic pressure) determined according to the operation amount of the brake pedal 52 (brake pedaling force).
Until the maximum value Gmax of the braking force that can be applied by the regeneration of the motor 46 to the front wheels 42 and 44 that are the driving wheels is exceeded, the braking force is applied to the front wheels 42 and 44 by regeneration, and the total braking force is the maximum regenerative braking force Gmax. When the value exceeds, the Rr hydraulic braking force is quickly raised to the initial value Gint, and then both the Rr hydraulic braking force and the Fr hydraulic braking force are increased in proportion to the brake pedal force. As a result, the braking force is, as shown as "whole" in FIG. 9, the M / C oil pressure is the maximum regenerative braking force Gmax.
When the pressure exceeds the predetermined pressure P0 corresponding to the above, the pressure rises in a short period of time, and before and after that, it rises according to the brake pedal force.

Therefore, as shown in FIG. 10, the ratio of the Fr hydraulic braking force to the Rr hydraulic braking force greatly changes before and after the former maximum regenerative braking force Gmax.
Front wheels (driving wheels) 42, 44 and rear wheels (idling wheels) 72, 74
The distribution of the braking force to the vehicle will approach the ideal distribution. The ideal distribution of the braking force to the front and rear wheels is shown by the symbol F0 in FIG. In the mode (normal mode) F1 in which the braking force by regeneration is not prioritized, the front wheels 42, 44 and the rear wheels 7 are
It is possible to control so that the braking force to 2,74 is as close as possible to this ideal distribution. On the other hand, in the conventional configuration in which only the regenerative braking is used up to the maximum regenerative braking force Gmax, and then the Fr braking force and the Rr braking force are applied, the distribution ratio of the braking forces is the ideal distribution as shown by reference numeral F3 in FIG. It is far from. On the other hand, in the present embodiment, the distribution of the braking force close to the ideal distribution is realized as indicated by the symbol F2.

As described above, according to this embodiment, 100% of the regenerative braking is utilized to efficiently collect the energy and the distribution ratio of the braking force can be improved. As a result, the one-charge traveling distance can be extended, the braking distance can be further shortened, and the braking characteristics can be improved.

Next, a third embodiment of the present invention will be described. FIG. 11 is a flowchart showing an outline of processing in the braking force control system as the third embodiment. This braking device is realized by the same hardware configuration as that of the second embodiment, and like the first embodiment, is intended to optimize the proportional distribution of the braking force between the front wheels 42, 44 and the rear wheels 72, 74. In addition, the control of the second embodiment is further improved. This processing is executed by the regenerative ECU 90.

Steps S240 and S in this embodiment
244 to S260 are the same as steps S200 and S204 to S220 in the second embodiment. Therefore, in this embodiment, the description of these steps is omitted. In this embodiment, there is no step corresponding to step S202 (setting of the initial value of Rr hydraulic braking force) in the second embodiment.

In this embodiment, in step S252,
When it is determined that the total system power is equal to or greater than the maximum regenerative braking force Gmax, first, the regenerative torque TB of the drive wheel motor 46 is controlled to the maximum regenerative braking force (step S260), and the regenerative braking force alone is insufficient. The existing braking force is applied in the form of friction braking force by hydraulic pressure, and this is distributed to the front and rear wheels. The allocation method is as follows. First, the R
It is determined whether or not the ratio of the r braking force to the Fr braking force (Rr braking force / Fr braking force) is less than or equal to a predetermined braking force distribution ratio (step S261). Immediately after the brake pedal 52 is depressed and the total braking force rises and exceeds the maximum regenerative braking force Gmax, almost no braking force is distributed to the rear wheels, so the Rr braking force / Fr braking force is less than or equal to a predetermined value. Has become. In this case, first, the braking force is preferentially distributed to the rear wheels 72 and 74, first the Fr brake hydraulic valve 70 is held in the closed state, and control is performed so that hydraulic braking is not applied to the front wheels 42 and 44. Yes (step S27
0).

Next, the Rr hydraulic braking force is obtained as a value obtained by subtracting the maximum regenerative braking force from the total braking force (step S27).
2) The Rr brake hydraulic valve 71 is controlled so that the Rr hydraulic braking force has this value (step S274). Actually, controlling the current supplied to the solenoid coil 118 of the hydraulic valve 71 is the same as in the other embodiments described above. With the above processing, as shown in FIG. 12, assuming that the total braking force K1 is the required braking force with respect to the brake pedal force, when the brake pedal force reaches the pressure P0 corresponding to the maximum regenerative braking force Gmax, the rear wheel 72 , 74 braking hydraulic pressure,
It is increased with an inclination equal to the total system power K1 (“Rr friction” shown in FIG. 12).

On the other hand, when it is determined in step S261 that the Rr braking force / Fr braking force is not less than the predetermined value, the Fr hydraulic braking force, Rr
The hydraulic braking force is calculated (step S262).

Overall braking force = Front wheel side braking force + Rear wheel braking force = (Fr hydraulic braking force + maximum regenerative braking force) + Rr hydraulic braking force (1) Rr braking force / Fr braking force = predetermined value (2)

When Rr braking force / Fr braking force is larger than a predetermined value, Rr braking force, F that satisfies the above equations (1) and (2)
Since the r braking force is found, the r braking force is obtained, and the hydraulic valve 71 for the Rr brake and the hydraulic valve 70 for the Fr brake are controlled so as to obtain the obtained braking force (step S26).
4). As a result, as shown in FIG. 12, the Fr braking force is
When the Rr braking force increases and reaches a predetermined ratio with respect to the maximum regenerative braking force, the Rr braking force starts to increase (“Fr friction” in FIG. 12), and at the same time, the increasing ratio of the Rr braking force shows the slope of the broken line K2. It is reduced (“Rr friction” in the figure).

According to the braking force control system of the third embodiment described above, the front wheels 42, 44 and the rear wheels 7 are the same as in the second embodiment.
It is possible to bring the distribution of the braking force with 2, 74 closer to the ideal distribution as much as possible to improve the balance of the distribution.
Compared with the embodiment, when the total braking force due to the brake pedal force exceeds the maximum regenerative braking force Gmax, the braking force of the rear wheels 72, 74 is increased in accordance with the required braking force.
The change in the braking force of the entire vehicle is smooth, and there is no discomfort in driving the vehicle.

Next, a fourth embodiment of the present invention will be described. Compared with the third embodiment, the braking force control device of the fourth embodiment has the same processing (FIG. 13) in most cases. That is, steps S240 to S260 of the third embodiment and steps S300 to S320 of the present embodiment are the same, and steps S270 to S274 of the third embodiment and steps S330 to 334 of the present embodiment are the same. (The 3-digit code differs by 60). Therefore, the configuration unique to this embodiment is step S322 and steps 340 to S334 shown in FIG.

In the present embodiment, when it is determined that the total braking force is equal to or greater than the maximum regenerative braking force Gmax (step S312), the regenerative torque TB of the motor 46 is controlled to the maximum regenerative braking force Gmax (step S320), and thereafter, It is determined whether or not the brake pedal force is a predetermined value BO2 or more (step S32).
2). As shown in FIG. 14, the predetermined value BO2 is set as a predetermined value larger than the predetermined value BO1 corresponding to the maximum regenerative braking force Gmax. Until the brake pedal force exceeds the maximum regenerative braking force Gmax and further increases by a predetermined amount, the process of steps S330 to S334, that is, the hydraulic valve 70 on the front wheels 42, 44 side is closed and the front wheels 42, 44 side is closed. Control is performed so that hydraulic braking is not applied (step S330), the Rr hydraulic braking force is obtained as a value obtained by subtracting the regenerative maximum braking force from the total braking force (step S332), and Rr hydraulic braking force is set to this value. Control the brake hydraulic valve 71 (step S334)
Of. As a result, the braking force of the front wheels 42 and 44 is maintained at the maximum regenerative braking force Gmax, as shown by the brake pedal force between BO1 and BO2 in FIG. On the other hand, the braking force of the rear wheels 72 and 74, which are idle wheels, increases in this section so as to compensate for the shortage of the required braking force, as indicated by "Rr friction" in the figure.

On the other hand, when the brake pedal force becomes larger than the predetermined value BO2 (step S322), a frictional force corresponding to the brake pedal force is first applied as the Fr braking force (step S340). The frictional force according to the brake pedal force is shown in Fig. 1.
It is obtained according to the straight line L2 shown in FIG. Furthermore, the rear wheels 7
A process of obtaining the friction braking force of 2,74 as a shortage of the total braking force is performed (step S342). That is,
The Rr hydraulic braking force is obtained according to the above-mentioned formula (1) total system power = front wheel braking force + rear wheel braking force = (Fr hydraulic braking force + maximum regenerative braking force) + Rr hydraulic braking force (1).

Thereafter, the hydraulic valves 70 and 71 are controlled so as to realize the calculated hydraulic braking force of each wheel (step S344). As a result, the brake pedal force is BO2.
In the above case, the braking force of the front wheels 42, 44 increases from the maximum regenerative braking force Gmax with the inclination set as the straight line L2, and the braking force of the rear wheels 72, 74 is the total braking force of the straight line L1. To increase.

In the braking device of the fourth embodiment described above, when the total braking force exceeds the maximum regenerative braking force Gmax when the brake pedal force increases, it is as if the braking force of the front wheels 42, 44 increases. The braking force is controlled so that it starts with a predetermined time delay with respect to the increase of the braking force of the wheels 72, 74. Therefore, the total braking force is smoothly increased, the feeling of braking is not impaired, and the front wheels 42, 44 and the rear wheels 72, 7 are not damaged.
4 can improve the imbalance of the braking force. In this embodiment, no special processing is performed so as to bring the braking force ratio of the front wheels 42, 44 and the rear wheels 72, 74 close to the ideal distribution, but the braking hydraulic pressure of the front wheels 42, 44 is increased.
By delaying the increase of the braking oil pressure of 2,74, the distribution of the braking force of both wheels can be brought closer to the proper distribution as a result.

Next, a fifth embodiment of the present invention will be described. The braking device of the fifth embodiment performs substantially the same processing (FIG. 15) as compared with the fourth embodiment. That is, steps S300 to S320 of the fourth embodiment are the same as steps S350 to S370 of the present embodiment, and steps S330 to S334 of the fourth embodiment are also the same as steps S380 to S384 of the present embodiment. (The three-digit code differs by 50). Therefore, the configuration unique to this embodiment has steps S373 and S3 shown in FIG.
90 to S394.

In this embodiment, when it is determined that the total braking force is not less than the maximum regenerative braking force Gmax (step S362), the regenerative torque TB of the motor 46 is controlled to the maximum regenerative braking force Gmax (step S370), and thereafter, It is determined whether the total system power is equal to or greater than a predetermined value G2 (step S37).
3). The predetermined value G2 is set as a predetermined value larger than the maximum regenerative braking force Gmax as shown in FIG. While the total system power exceeds the maximum regenerative braking force Gmax to the predetermined value, steps S380 to S380 are performed.
384, that is, the hydraulic valve 70 on the front wheels 42, 44 side
Is controlled to prevent the hydraulic braking from acting on the front wheels 42, 44 (step S380), and the Rr hydraulic braking force is obtained as a value obtained by subtracting the regenerative maximum braking force from the total braking force (step S382). The Rr brake hydraulic valve 71 is controlled so that the braking force has this value (step S384). As a result, the braking force of the front wheels 42, 44 is maintained at the maximum regenerative braking force Gmax, as shown in FIG. 16 as the braking force being up to the maximum regenerative braking force Gmax. On the other hand, the braking force of the rear wheels 72 and 74, which are idle wheels, increases at a constant rate as indicated by "Rr friction" in the figure (straight line N2). Therefore, in this section, the shortage of the total braking force cannot be completely compensated by the braking force of the rear wheels 72, 74, and the characteristic of the braking force becomes gentle.

On the other hand, when the total braking force becomes larger than the predetermined value G2 (step S373), first, the friction force corresponding to the brake pedal force is applied as the Fr braking force (step S390). The frictional force according to the brake pedal force is shown in FIG.
It is obtained according to the straight line N3 shown. Furthermore, the rear wheels 72, 7
The friction braking force of No. 4 is obtained by using the previously used characteristic (straight line N2) as it is (step S392).

After that, the hydraulic valves 70 and 71 are controlled so as to realize the calculated hydraulic braking force of each wheel (step S394). As a result, when the total braking force becomes equal to or larger than the predetermined value G2, the braking force of the front wheels 42, 44 increases from the maximum regenerative braking force Gmax with the inclination set as the straight line N3. In this embodiment, when the total braking force becomes equal to or greater than the maximum regenerative braking force Gmax, the braking force of the rear wheels 72, 74 is not calculated as a supplement to the insufficient braking force, but a predetermined characteristic (straight line N2). In this region, the total braking force shows a gentle characteristic as a whole.

In the braking apparatus of the fifth embodiment described above, when the total braking force exceeds the maximum regenerative braking force Gmax when the brake pedal force increases, it is as if the front wheels 42, 44 were the same as in the fourth embodiment. The braking force is controlled so that the increase of the braking force starts with a delay of a predetermined time with respect to the increase of the braking force of the rear wheels 72, 74. Therefore, the front wheels 42 and 44 and the rear wheels 72 and 74
It is possible to improve the imbalance of the braking force of the. In this embodiment, no special processing is performed so as to bring the braking force ratio of the front wheels 42, 44 and the rear wheels 72, 74 close to the ideal distribution, but the braking hydraulic pressure of the front wheels 42, 44 is increased.
By delaying the increase of the braking oil pressure of 2,74, the distribution of the braking force of both wheels can be brought closer to the proper distribution as a result.

Next explained is the sixth embodiment of the invention. The braking device described below is intended to detect the lock of the wheels and appropriately distribute the braking force, and the braking device of the sixth embodiment is particularly the step S2 of the third embodiment.
This is a change of 50 or less. The processing is shown in FIG. That is, the braking device of the sixth embodiment calculates the total braking force based on the straight line K1 shown in FIG. 12 (step S
250), it is determined whether or not the wheels are locked (step S400). The lock of the wheels can be detected from a detection result of a wheel speed sensor (not shown) by a simple determination such as whether or not the differential value thereof is less than a predetermined value.

If the wheels are not locked,
The process proceeds to step S252 (FIG. 11) and executes the above-described process (see FIG. 11). At this time, the control characteristic of the braking force becomes the same as that of the regeneration priority mode shown in FIG.
On the other hand, when it is determined that the wheel lock has occurred,
Assuming that the Rr brake hydraulic valve 71 is forcibly opened (step S402) and the braking force due to friction is applied to the rear wheels 72 and 74, the Rr hydraulic braking force follows the normal mode shown in FIG. 18 and the frictional force based on the straight line L4. Is set (step S404). In a succeeding step S406, the hydraulic valve 71 is controlled to perform processing for matching the actual braking force with this.

As a result, as shown in FIG. 18, even if the total braking force is equal to or less than the maximum regenerative braking force Gmax, if the wheels are locked, the braking force using hydraulic pressure to the rear wheels 72, 74 will be generated. The added braking force of the rear wheels 72, 74,
The overall braking force also increases (from x mark to ● mark). The Rr friction braking force is not originally applied below the regenerative maximum braking force Gmax, but is applied to the rear wheels 72 and 74 in accordance with the straight line L4 in order to keep the distribution ratio of the braking force appropriate when the lock occurs. As a result, the distribution of the front wheels 42, 44 and the rear wheels 72, 74 is forcibly approximated to the ideal distribution, and the front wheels 42, 44 that are the driving wheels are prevented from being locked.

Then, it is determined whether or not the total braking force is equal to or greater than the predetermined value G3 (step S408). As shown in FIG. 18, the overall braking force when the lock is generated is the regenerative braking force (Fr regeneration in the figure) to which the Rr friction braking force is applied. The braking force by the regeneration to the front wheels 42 and 44 is
Since it does not increase above the regenerative maximum braking force Gmax, the point at which the application of friction braking force using hydraulic pressure to the front wheels 42, 44 is started from the total braking force is found based on the predetermined value G3. When the total system power is smaller than the predetermined value G3, the Fr brake hydraulic valve 70 is held in the closed state (step S420), and the process for obtaining the total braking force is performed according to the following equation (3) (step S422). Driving force regenerative braking force based on total system power = L6 + Rr hydraulic braking force (3)

That is, when it is determined that the total braking force is less than the predetermined value G3 and the lock is generated, the braking force of the vehicle is the braking force applied to the front wheels 42 and 44 by the regeneration and the hydraulic pressure generated in the brake master cylinder 54. Rear wheels 72 by distributing,
It is the sum of the friction braking force applied to 74. On the other hand, when the total braking force becomes equal to or greater than the predetermined value G3 (step S40
8) First, it is assumed that the friction braking force applied to the front wheels 42 and 44 is used, and the process of controlling the regenerative torque TB to the maximum regenerative braking force Gmax is performed (step S410). After that, a process for controlling the braking force of the vehicle as the sum of the maximum regenerative braking force Gmax, the Rr hydraulic braking force (according to the straight line L4) and the Fr braking force determined according to the straight line L5 is performed (step S412). After that, the process goes to "END" and the processing routine is ended.

According to the sixth embodiment described above, the wheel is locked with the braking force control mode when the wheel is locked and the braking force control mode when the wheel is not locked. In this case, even if the total braking force is less than the maximum regenerative braking force Gmax, the friction braking force is applied to the rear wheels 72, 74. Therefore, the front wheels 42, 44 and the rear wheels 7
2,74 will be braked, and the distribution ratio of the braking force will approach the ideal distribution. Since the distribution of the braking force of both wheels approaches the ideal distribution that is unlikely to cause lock,
The lock is released, and the occurrence of slippage is prevented.

When the occurrence of lock is detected, the rear wheels 72,
When the friction braking force by hydraulic pressure is applied to 74, the process of gradually increasing the braking force is not shown in the flowchart of FIG. 17, but in the actual control, so-called smoothing process is performed to gradually increase the braking force. However, abrupt changes in the braking force ratio are avoided. Therefore, the ratio of the braking force does not suddenly change and some trouble does not occur.

Next, a seventh embodiment of the present invention will be described. As shown in FIG. 19, the braking device 580 of the seventh embodiment has the same structure as the hardware described as the first embodiment (see FIG. 2) but with the anti-lock brake system (hereinafter, referred to as “A”).
(Abbreviated as BS) is added, and an ABS ECU 96 and an ABS actuator 98 are provided as a new configuration. The ABS ECU 96 is a control device that controls the ABS actuator 98 while exchanging information with the regenerative ECU 90, and like the other ECUs, the CPU, ROM,
It has a RAM and an input / output I / F. Further, the ABS actuator 98 includes a hydraulic valve 70 and a hydraulic valve 71 in the hydraulic system for the front wheels 42, 44 and the rear wheels 72, 74.
And the front wheel cylinders 62, 64 and the rear wheel cylinders 82, 84 are provided between the brake master cylinder 54 and the hydraulic valve 70,
Front wheel cylinder 6 via hydraulic valve 71
2, 64 and rear wheel cylinders 82, 84 are actuators that control the hydraulic pressure applied.

In this embodiment, the ABS ECU 96 reads the signals from the wheel speed sensors 99a to 99d provided for each wheel, and when it determines that the wheels are locked, it controls the ABS actuator 98 to control the front wheels. Cylinders 62 and 64, rear wheel cylinder 8
The well-known anti-lock control is independently performed such that the hydraulic pressure applied to 2, 84 is temporarily reduced and the hydraulic pressure is increased again when the wheels are unlocked. ABS
The ECU 96 uses the wheel speed sensor 99 for the front wheels 42, 44.
The signals from a and 99b are output to the regenerative ECU 90, and the antilock control execution state is notified to the regenerative ECU 90 when the ABS operates.

Regarding the processing executed by the regenerative ECU 90,
It will be described with reference to FIG. When this braking process is started,
First, initialization processing is performed (step S600), and then it is determined whether the brake switch is turned on (step S602). Whether the brake switch is turned on or off is determined by detecting an increase in the hydraulic pressure of the brake master cylinder 54 as in the other embodiments described above. If the brake switch is off, there is no request for braking, so the front and rear hydraulic valves 70 and 71 are kept closed and no braking is applied to the wheels (step S604).

On the other hand, when it is determined that the brake switch is on (step S602), the current regenerative torque is calculated (step S606), and the front wheels 42, 44 are
It is determined whether or not is locked (step S6).
08). ABS ECU96 locks the front wheels 42 and 44.
The regenerative ECU 90 makes a determination based on the wheel speeds of the front wheels 42, 44 received from. The locking of the front wheels 42, 44 referred to here does not mean a lock in which the ABS ECU 96 operates the anti-lock control, that is, a state in which a slip that cannot be overlooked is generated, but braking by regenerative braking is applied to the front wheels 4 and 4.
It refers to the locking tendency of the front wheels 42,44 that results from being applied only to 2,44. When it is determined that the front wheels 42, 44 are not locked, the process proceeds to step S609, and normal braking force control is performed. As the normal braking force control, any of the controls described as the first to sixth embodiments or the similar control can be adopted.

When it is determined that the front wheels 42, 44 are locked, the hydraulic valve 71 on the rear wheels 72, 74 side is opened, and the rear wheel cylinders 82, 84 of the rear wheels 72, 74 are opened.
Then, the M / C hydraulic pressure is supplied to the clutch to apply the braking force by friction (step S610). As for the magnitude of the friction braking force, the idea shown in each of the above-described embodiments can be applied. Then, it is determined whether it is necessary to operate the ABS actuator 98 (step S61).
4). If you need to activate the ABS,
At the same time when the regenerative torque is reduced, a command is issued to the ABS ECU 96 to drive the ABS actuator 98 to perform the ABS operation (step S616). The process of reducing the regenerative torque mentioned here includes a process of reducing the regenerative torque to zero.

Thereafter, the current wheel speed is calculated based on the signals of the wheel speed sensors 99a and 99b of the front wheels 42 and 44 received from the ABS ECU 96 (step S62).
0), the above-mentioned processing is repeated from step S602 again.

According to the embodiment described above, in a region where the brake pedal force is small, all the braking force is covered by regeneration, but if the front wheels 42, 44 are easily locked on a low μ road or the like, this is detected. Then, the rear wheels 72, 74 are provided with friction braking force by the M / C hydraulic pressure, and the front wheels 42, 4 are regenerated by regeneration.
The braking force of 4 is reduced. Therefore, even if the braking by the regeneration is prioritized, the braking force can be distributed to the front and rear wheels to avoid the wheel lock and shorten the braking distance under the condition that the wheels are likely to be locked due to the road surface condition or the like. . After that, when the brake pedal force further increases and the ABS ECU 96 detects the slip of the wheel and operates the ABS actuator 98 to restrict the braking of the wheel by the M / C hydraulic pressure, the regenerative torque of the front wheels 42, 44 is reduced. Since the frictional braking force due to the hydraulic pressure is also increased, ABS ECU
By 96, the anti-brake can be effectively applied to prevent the vehicle from slipping. As a result, there is an advantage that the reliability of the ABS is improved and the energy can be effectively recovered by the regenerative braking by using the conventional ABS as it is.

Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, a configuration applied to a rear wheel drive vehicle, an internal combustion engine together with a motor as a drive source is used. Needless to say, the present invention can be implemented in various modes, such as a configuration applied to a so-called hybrid vehicle used together or a configuration applied to a four-wheel drive vehicle without departing from the scope of the present invention.

[0080]

As described above, the first and second aspects of the present invention
According to the braking system of the electric vehicle described above, when the required braking force exceeds the maximum braking force that can be applied to the regenerative wheels due to the regeneration, the distribution of the braking force between the regenerative wheels and the non-regenerative wheels can be brought close to an appropriate distribution. It has an excellent effect that it can be done. Therefore, the braking characteristics of the vehicle are improved, and it is possible to contribute to shortening the braking distance.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a basic configuration of a braking device for an electric vehicle according to the present invention.

FIG. 2 is a schematic configuration diagram of a braking device 40 as a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration of a hydraulic valve 70 together with a hydraulic system.

FIG. 4 is an explanatory diagram showing the operating principle of the hydraulic valve 70.

FIG. 5 is a graph showing distribution of braking force in a vehicle.

FIG. 6 is a flowchart showing a braking force control processing routine in the first embodiment.

FIG. 7 is a graph showing distribution of braking force in the first embodiment.

FIG. 8 is a flowchart showing a braking force control routine as a second embodiment.

FIG. 9 is a graph showing distribution of braking force in that case as well.

FIG. 10 is a graph illustrating the relationship between Fr braking force and Rr braking force in that case as well.

FIG. 11 is a flowchart showing a braking force control routine as a third embodiment.

FIG. 12 is a graph showing distribution of braking force in that case as well.

FIG. 13 is a flowchart showing a braking force control routine as a fourth embodiment.

FIG. 14 is a graph showing distribution of braking force in that case as well.

FIG. 15 is a flowchart showing a braking force control routine as a fifth embodiment.

FIG. 16 is a graph showing distribution of braking force in that case as well.

FIG. 17 is a flowchart showing a main part of a braking force control routine as a sixth embodiment.

FIG. 18 is a graph showing distribution of braking force in that case as well.

FIG. 19 is a schematic configuration diagram of a braking device 580 according to a tenth embodiment of the present invention.

FIG. 20 is a flowchart showing a braking force control routine of the same.

FIG. 21 is an explanatory diagram showing a braking situation in conventional braking force control.

[Explanation of symbols]

 40 ... Braking device 42, 44 ... Front wheel 46 ... Motor 48 ... Battery 50 ... Inverter 52 ... Brake pedal 54 ... Brake master cylinder 56 ... Reservoir 58 ... Brake simulator 60 ... Hydraulic pressure sensor 62, 64 ... Front wheel cylinder 68 ... Hydraulic pipe 70 Fr brake (front) hydraulic valve 71 ... Rr brake hydraulic valve 72, 74 ... Rear wheel 72, 74 ... Other rear wheel 78 ... Hydraulic pipe 80 ... Pressure valve 82, 84 ... Rear wheel cylinder 90, 92, 94 ... ECU 90 Regeneration ECU 90a, 92a, 94a ... CPU 90b, 92b, 94b ... ROM 90c, 92c, 94c ... RAM 90d, 92d, 94d ... Input / output I / F 92 ... Motor ECU 94 ... Battery ECU 96 ... ABS ECU 98 ... ABS actuator 99a 99d ... Wheel speed sensor 100 ... Master cylinder port 102 ... Sub port 104 ... Wheel cylinder port 110 ... Pressure increasing side poppet valve 112 ... Pressure reducing side poppet valve 114 ... Ball 116 ... Shaft 117 ... Flow path 118 ... Solenoid coil 119 ... Plunger 120 ... Ball 580 ... Braking device M1 ... Regenerative braking force applying means M2 ... Friction braking force applying means M3 ... Regenerative wheel braking means M4 ... Braking force distribution ratio determining means M5 ... Braking force control means M10 Braking force applying delay means MM ... Motor W1 ... Regeneration Wheel W2 ... Non-regenerative wheel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Ito 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (6)

[Claims] 1. A braking device for an electric vehicle, which applies a braking force to each wheel of a vehicle based on a required braking force, wherein regenerative braking force can be applied to at least one of the wheels using regeneration by an on-vehicle motor. The regenerative braking force applying means, the friction braking force applying means that can independently apply the braking force by friction to the regenerative wheel that applies the braking by the regenerative operation and the non-regenerative wheel that does not apply the braking by the regenerative operation, and the required braking force When the braking force is less than the maximum braking force that can be applied by the braking force applying unit, the regenerative wheel braking unit that brakes the regenerative wheel by the regenerative braking force applying unit, and when the required braking force exceeds the maximum braking force , A braking force distribution ratio determining means for determining the distribution ratio of the braking force between the regenerative wheels and the non-regenerative wheels in a manner close to an ideal distribution in consideration of the braking force by the regeneration, and based on the determined distribution ratio , Said regeneration And non-regenerative wheel braking device for an electric vehicle and a braking force control means for applying a braking force by the friction the friction braking force applying means. 2. The braking device for an electric vehicle according to claim 1, wherein the braking force distribution ratio determining means determines a shortage of the braking force when the required braking force exceeds the maximum braking force. The braking force due to friction is distributed between the regenerative wheel and the non-regenerative wheel, and the non-regenerative wheel is predominantly distributed until the distribution ratio of the braking force between the regenerative wheel and the non-regenerative wheel reaches a predetermined ratio. And a means for determining the distribution ratio according to the ideal distribution after the distribution ratio of the braking force reaches the predetermined ratio. 3. A braking device for an electric vehicle, which applies a braking force to each wheel of a vehicle on the basis of a required braking force, wherein regenerative braking force can be applied to at least one of the wheels using regeneration by an on-vehicle motor. The regenerative braking force applying means, the friction braking force applying means that can independently apply the braking force by friction to the regenerative wheel that applies the braking by the regenerative operation and the non-regenerative wheel that does not apply the braking by the regenerative operation, and the required braking force When the braking force is less than the maximum braking force that can be applied by the braking force applying unit, the regenerative wheel braking unit that brakes the regenerative wheel by the regenerative braking force applying unit, and when the required braking force exceeds the maximum braking force The insufficient braking force is applied to the non-regenerative wheel as a braking force due to friction by the friction braking force applying means, and the braking force due to friction is applied to the regenerative wheel after the application of the braking force. Control Braking apparatus for an electric vehicle that includes a force applying delay means. 4. The braking force application delaying means is means for applying a braking force due to friction to the regenerative wheel after the braking force due to friction to the non-regenerative wheel reaches or exceeds a predetermined value. A braking device for the electric vehicle described. 5. The braking force application delaying means is means for applying a braking force due to friction to the regenerative wheel after the required braking force exceeds a judgment value larger than the maximum braking force. A braking device for the electric vehicle described. 6. The braking force application delay means is configured such that the ratio between the maximum braking force applied to the regenerative wheel and the braking force due to friction on the non-regenerative wheel reaches an ideal distribution ratio, and then the regenerative wheel is provided. 4. A means for applying a braking force by friction to
A braking device for the electric vehicle described.