JPH0731005A - Regenerative brake controller for electric automobile - Google Patents

Abstract

PURPOSE:To allow positive and satisfactory braking, as required, by generating sufficient braking power from a mechanical brake system even when the charging amount of battery drops and it is hauled. CONSTITUTION:The regenerative brake controller for electric automobile comprises a mechanical brake system M1 operable hydraulically by the a working fluid in response to the stepping of a brake pedal BP, a regenerative brake system M2 operable at least at the time of braking, a battery M3 feeding power at least to a running motor DM and charged with power generated from the regenerative brake system, and a unit M4 being fed with power selectively from the battery and imparting predetermined pressure to the working fluid. When a charging amount detector M5 detects the charging amount of the battery lower than a predetermined level and a hauled state detector M6 detects a hauled state of automobile, a controller M7 actuates the regenerative brake system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle having a mechanical braking device and a regenerative braking device, and more particularly to a control device for the regenerative braking device.

[0002]

2. Description of the Related Art As an electric vehicle that is driven by a driving motor that is rotated by electric power supplied from a battery, as described in, for example, Japanese Unexamined Patent Publication No. Hei 1-119821, the brake pedal is depressed. In response to the pressure of the working fluid, a mechanical brake device, an electric pump that applies a required high or negative pressure to the working fluid, and a regenerative braking device that operates at least during braking. Electric vehicles are known from the prior art which are arranged to be braked by a mechanical braking force and a regenerative braking force respectively generated by the device.

According to such an electric vehicle, the braking force is also generated by the regenerative braking device during braking of the vehicle, and a part of the braking energy is recovered as electric power by the regenerative braking device to charge the battery. As compared with the case of an electric vehicle that does not have a regenerative braking device, effective braking can be performed, and consumption of battery power can be delayed.

[0004]

In the conventional electric vehicle as described above, the electric power of the battery is consumed and the amount of charge of the battery is reduced due to the vehicle traveling over a specified traveling distance determined by full charging of the battery. When the traveling motor is lowered below the level at which it can be normally rotated, the vehicle cannot run on its own and must be moved to the charging facility by being towed by another vehicle.

Further, when the charged amount of the battery drops below a predetermined level, the electric pump for the mechanical brake device is not normally driven to rotate and sufficient pressure cannot be applied to the working fluid, so that the mechanical brake device is not provided. The braking force generated by is reduced. However, the regenerative braking device, which is the other braking device, cannot generate a braking force for completely stopping the vehicle, and can generate electric power by regeneration only when the vehicle is self-propelled.

Therefore, when a conventional electric vehicle is towed by another vehicle due to a decrease in the amount of charge of the battery, for example, when adjusting the inter-vehicle distance to the towing vehicle on a slope or stopping at a signal, etc. Even when it is necessary to brake the vehicle as described above, there is a problem that the vehicle cannot be braked satisfactorily and reliably.

In view of the above problems in the conventional electric vehicle as described above, the present invention provides a sufficient braking force by the mechanical brake device even when the battery charge is reduced and the vehicle is towed. It is an object of the present invention to provide an improved control device for a regenerative braking device of an electric vehicle, which can be generated and thereby can satisfactorily and reliably brake the vehicle as necessary.

[0008]

According to the present invention, as described above, a mechanical brake device, which is operated by the pressure of a working fluid in response to depression of a brake pedal BP, is provided. M1, at least a regenerative braking device M2 that operates during braking, at least a battery M3 that supplies electric power to the traveling motor DM and is charged with electric power generated by the regenerative braking device, and selectively from the battery. A charge amount detecting means M5 for detecting a charge amount of the battery and a regenerative braking control device for an electric vehicle having a pressure applying means M4 which is supplied with electric power and applies a required pressure to the working fluid. The towed state detecting means M6 for detecting the towed state, and the regenerative braking device when the charge amount is less than a predetermined value and the vehicle is in the towed state. Is achieved by the regenerative braking device for the control apparatus for an electric vehicle, characterized in that a control means M7 for actuating the.

[0009]

According to the above-mentioned structure, the charge amount detecting means M5
When the amount of charge of the battery M3 detected by is less than a predetermined value and the towed state detecting means M6 detects that the vehicle is in the towed state, the control means M7 activates the regenerative braking device M2. As a result, the battery is charged with the electric power generated by the regenerative braking device.
Therefore, even when the vehicle is in the towed state, the charge amount of the battery is maintained at a charge amount that can normally operate the pressure applying means M4 and apply the required pressure to the working fluid, and thus the mechanical brake device M1. Brake pedal BP
Sufficient mechanical braking force is generated in response to the depression of the vehicle, which makes it possible to satisfactorily and reliably brake the vehicle as necessary.

[0010]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic block diagram showing one embodiment of a control device for a regenerative braking device according to the present invention applied to an electric vehicle equipped with a brake by-wire type braking device, and FIG. 3 is shown in FIG. It is a block diagram which shows the electronic control unit.

In FIG. 2, reference numeral 10 denotes a traveling motor, and the motor 10 rotationally drives a drive wheel (not shown) via a differential device 12 and an axle 14. . The motor 10 includes a drive circuit 18 that incorporates a converter that converts a direct current from the battery 16 into an alternating current.
It is designed to be rotationally driven by a drive current supplied through the drive current, and the drive current is the accelerator pedal depression amount A.
The microcomputer 24 of the electronic control unit 22 for traveling is controlled based on the signal from the depression amount detection sensor 20 for detecting p according to the depression amount Ap of the accelerator pedal.

The electric vehicle of the illustrated embodiment has a brake by.
A brake master cylinder having a wire type mechanical brake device 26, which is driven by a brake pedal 28 and supplies hydraulic pressure to stroke simulators 32fr, 32fl, 32r via electromagnetic switching valves 30fr, 30fl, 30r. It has 34. The braking device 26 also generates braking force by selectively supplying hydraulic pressure to wheel cylinders 38fr, 38fl that cooperate with wheel discs 36fr, 36fl provided on a pair of drive wheels not shown in the figure. Actuator 40
Braking force is generated by selectively supplying hydraulic pressure to wheel cylinders 44rr and 44rl that cooperate with fr and 40fl and wheel discs 42rr and 42rl respectively provided on a pair of driven wheels (not shown). And an actuator 46.

Although not shown in FIG. 2, the actuators 40rr, 40rl, and 46 are a reservoir for storing oil as a working fluid, an electric pump for pumping the oil from the reservoir and pressurizing the oil, and a discharge from the pump. It has a common member with an accumulator that stores high-pressure oil, and the corresponding wheel cylinders 38fr, 38fl,
It has a control valve for controlling the hydraulic pressure supplied to 44rr and 44rl as an individual member. Since the brake device 26 itself does not form the subject of the present invention and is well known in the art, further description of the brake device will be omitted. See Japanese Patent Application Laid-Open No. 4-232168, which is the same application as the applicant.

As shown, the actuators 40rr, 40
The control valves of rl and 46 are pedal force B to the brake pedal 28.
The voltage Ea of the drive current supplied from the drive circuit 50 on the basis of the signal from the pedal force detection sensor 48 for detecting p is controlled by the microcomputer 54 of the braking electronic control unit 52 according to the pedal force on the accelerator pedal. ing. Further, the switching valves 30fr, 30fl, 30r are normally maintained in the switching position shown in FIG. 2, and the brake master cylinder 34 and the actuators 40rr, 40rl, 46r.
The communication between the brake master cylinder 34 and the stroke simulators 32fr, 32fl, 32r is cut off by supplying a drive current from the drive circuit 56 when the pedal force detection sensor 48 or the like is abnormal. 34 and wheel cylinders 38fr, 38f
It is switched to a position where l, 44rr, 44rl are in communication,
As a result, the hydraulic pressure of the brake master cylinder 34 is directly supplied to each wheel cylinder.

Further, in the illustrated embodiment, the traveling motor 10 constitutes the regenerative braking device 60 in cooperation with the regenerative circuit 58 and also functions as a regenerative motor. The regenerative circuit 58 has a built-in inverter for converting an alternating current into a direct current, and is switched between an on state and an off state in response to a command signal from the microcomputer 24 of the electronic control unit 22, and particularly in the on state. Motor 10
When the battery functions as a regenerative motor, the electric power generated by the motor is supplied to the battery 16.
The SOC E of the battery 16 is detected by the SOC meter 62.

As shown in detail in FIG. 3, the microcomputer 54 of the electronic control unit 52 has a general configuration, and includes a central processing unit (CPU) 70, a read only memory (ROM) 72, and It has a random access memory (RAM) 74, an input port device 76, and an output port device 78, which are connected to each other by a bidirectional common bus 80.

The input port device 76 is supplied with a signal indicating the pedal effort Bp with respect to the brake pedal 28 detected by the pedal effort sensor 48, and a signal indicative of the accelerator pedal depression amount Ap detected by the pedal depression amount sensor 20, S.
A signal indicating the charge amount E of the battery 16 detected by the OC meter 62, an ignition switch (IGSW) 8
A signal indicating whether 2 is in the ON state, a signal indicating whether the starter switch (STSW) 84 is in the ON state, and a signal indicating the vehicle speed V detected by the vehicle speed sensor 86 are input via the microcomputer 24. And further in FIG.
Although not shown in the figure, a signal indicating the drive current Id supplied to the traveling motor 10 is input from the microcomputer 24. The input port device 76 appropriately processes the signal input thereto, and outputs the processed signal to the CPU and the RAM 74 according to the instruction of the CPU 70 based on the control program stored in the ROM 72.

The ROM 72 stores a braking control program shown in FIG. 4 and a map corresponding to the graph shown in FIG. The CPU 70 is adapted to perform various calculations and signal processing based on the control program shown in FIG. The output port device 78 follows the instructions of the CPU 70 and the actuators 40rr and 40rl via the drive circuit 50 according to the pedaling force Bp to the brake pedal 28, as will be described later.
The mechanical braking force is controlled by outputting a control signal to the control valve of 46, and if necessary, the microcomputer 24
By controlling the operation of the regenerative braking device 60 by outputting a control signal to the drive circuit 18 and the regenerative circuit 58 via
When the pedal force sensor 48 is abnormal, a control signal is output to the switching valves 30fr, 30fl, 30r via the drive circuit 56.

Although not shown in the figure, the microcomputer 24 of the traveling electronic control unit 22 is also constructed in the same manner as the microcomputer 54 described above.

Next, the braking control in the illustrated embodiment will be described with reference to the flow chart shown in FIG.
The control by the electronic control unit 52 is started by closing the ignition switch 82. Further, in the flowchart shown in FIG. 4, the flag F relates to whether or not the regenerative braking device 60 is operated while the electric vehicle is being towed, and 1 is the regenerative braking device is operated. It is shown that.

First, in step 10, the pedal force sensor 48 is used.
Pedaling force Bp on the brake pedal 28 detected by
Is read, and in step 20, it is judged whether or not the charge amount E of the battery 16 is less than the reference value Eo (a positive constant), and it is determined that E <Eo. When the determination is made, the routine proceeds to step 70, and when it is determined that E <Eo is not established, the routine proceeds to step 30.

In step 30, the starter switch 8
4 is in the ON state, and when it is determined that the starter switch is not in the ON state, the process proceeds to step 60, and it is determined that the starter switch is in the ON state. Sometimes, it is determined whether or not the accelerator pedal depression amount Ap is zero. When it is determined that Ap = 0, that is, the accelerator pedal is not depressed, the drive circuit 18 is set to the off state and the regeneration circuit 58 is set to the on state in step 50. By the switching setting, the regenerative braking device 60 is actuated, and it is determined that Ap = 0,
That is, when it is determined that the accelerator pedal is in the depressed state, the regenerative circuit is set to the off state and the drive circuit is set to the on state in step 60, whereby the regenerative braking device is activated. The operation is released.

In step 70, for example, the drive current Id to the traveling motor 10 is 0 and the vehicle speed V is the reference value Vo.
(Positive constant) It is determined whether or not the vehicle is in the traveling state while the traveling motor is in the non-driving state by determining whether or not the traveling motor is in the non-driving state. When it is determined that the vehicle is in the traveling state, the process proceeds to step 110, and when it is determined that the traveling motor is in the driving state or the vehicle is substantially in the stopped state, step 80 is performed. Go to.

In step 80, it is judged whether or not the flag F is 1, and when it is judged that F = 0, the process directly returns to step 10 and it is judged that F = 1. When the determination is made, the operation of the regenerative braking device 60 is released in step 90, the flag F is reset to 0 in step 100, and then step 10 is performed.
Return to.

In step 110, the regenerative braking device is operated, and in step 120 the flag F is set to 1. In step 130, the brake pedal 2
Based on the pedaling force Bp for 8, each actuator 40fr, 4
The drive current voltage Ea supplied to the control valves of 0fl and 46 is calculated from the map corresponding to the graph shown in FIG.
In step 140, the driving current of the voltage Ea is supplied to the control valve of each actuator, whereby the wheel cylinders 38fr, 38fl, 44rr, 44rl of each wheel generate a braking force corresponding to the pedaling force Bp on the brake pedal. Then, the process returns to step 10.

Thus, according to the illustrated embodiment, when the power of the battery 16 is consumed and the vehicle is being towed by another vehicle, a yes determination is made in steps 20 and 70, respectively, and in step 110. The regenerative braking device 60 is actuated, whereby the electric power generated by the motor 10 is charged in the battery 16 via the regenerative circuit 58, and the battery charge amount E is the actuator 40f.
If the brake pedal 28 is depressed while the vehicle is being towed by maintaining a sufficient amount of charge to operate r, 40fl and 46, steps 130 and 1
At 40, a mechanical braking force is satisfactorily and reliably generated by the brake device 26 in accordance with the pedaling force Bp on the brake pedal.

When the charge amount E of the battery 16 is a sufficient charge amount for rotationally driving the traveling motor 10, a negative determination is made in step 20, and when the vehicle is in the self-propelled state. The determination of yes is made in step 30, and the regenerative braking device 60 is operated only when the accelerator pedal is not depressed in steps 40 and 50, whereby the electric power generated by the motor 10 is supplied to the battery 16. Be charged.

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

For example, in the illustrated embodiment, the mechanical brake device is a brake by wire type brake device 26, but the mechanical brake device according to the present invention is a brake master cylinder driven by a brake pedal 28. Three
Hydraulic pressure or negative pressure is directly applied to the wheel cylinder 3 of each wheel
It may be a hydraulic brake device or a vacuum brake device that is supplied to 8fr, 38fl, 44rr, and 44rl.

Further, in the embodiment shown in the drawing, the drive current Id to the motor is 0 and the vehicle speed V is determined in order to judge whether the vehicle is in the traveling state while the traveling motor 10 is not driven. The determination is made as to whether or not the value is equal to or greater than the reference value Vo. However, the determination as to whether or not the vehicle is in the traveling state with the traveling motor in the non-driving state is made by determining the accelerator pedal depression amount Ap. It may be performed by determining whether or not the vehicle speed V is substantially 0 and is equal to or higher than the reference value Vo.

In the illustrated embodiment, the regenerative braking device 60 always operates when the vehicle is self-propelled when the amount of depression of the ascele pedal is 0, and functions like engine braking when the vehicle decelerates. However, the regenerative braking device uses the brake pedal 28 when the vehicle is self-propelled.
It may operate only when the vehicle is depressed, that is, only when the vehicle is being braked.

Further, in the illustrated embodiment, the traveling motor 10 also functions as the motor of the regenerative braking device 60, but the motor of the regenerative braking device according to the present invention is the traveling motor 10. It may be provided as a motor independent of.

[0034]

As is apparent from the above description, according to the present invention, the charge amount of the battery M3 detected by the charge amount detecting means M5 is less than the predetermined value and the towed state detecting means M6 is used to drive the automobile. When it is detected that the vehicle is in the towed state, the regenerative braking device M2 is operated by the control means M7, whereby the battery is charged with the electric power generated by the regenerative braking device. Therefore, even when the vehicle is in the towed state, the charge amount of the battery is determined by the pressure applying means M.
4 is normally operated and the amount of charge is maintained so that a required pressure can be applied to the working fluid, so that a sufficient mechanical braking force is generated by the mechanical brake device M1 in response to the depression of the brake pedal BP. As a result, the towed vehicle can be braked satisfactorily and reliably as required.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a control device for a regenerative braking device for an electric vehicle according to the present invention, corresponding to the claims.

FIG. 2 is a schematic configuration diagram showing one embodiment of a control device for a regenerative braking device according to the present invention, which is applied to an electric vehicle equipped with a brake by-wire type mechanical braking device.

FIG. 3 is a block diagram showing the electronic control device shown in FIG. 2.

FIG. 4 is a flowchart showing a braking control routine achieved by the electronic control unit shown in FIGS. 2 and 3.

FIG. 5 is a graph showing the relationship between the pedal effort Bp applied to the brake pedal and the voltage Ea of the drive current applied to the actuator.

[Explanation of symbols]

 Reference numeral 10 ... Traveling motor 16 ... Main battery 22 ... Traveling electronic control device 26 ... Mechanical braking device 28 ... Brake pedals 40fr, 40fl, 46 ... Actuator 48 ... Treading force sensor 52 ... Braking electronic control device 60 ... Regenerative braking device 62 ... SOC meter

Claims (1)

[Claims] 1. A mechanical brake device that operates by the pressure of a working fluid in response to depression of a brake pedal, a regenerative brake device that operates at least during braking, and at least electric power is supplied to a traveling motor to provide the regenerative brake. A control device for a regenerative braking device for an electric vehicle, comprising: a battery charged with electric power generated by the device; and a pressure applying means for selectively supplying electric power from the battery to apply a required pressure to the working fluid. A charged amount detecting means for detecting the charged amount of the battery, a towed state detecting means for detecting a towed state of the vehicle, and a charged amount less than a predetermined value when the vehicle is in the towed state. A control device for a regenerative braking device for an electric vehicle, comprising: a control unit that operates the regenerative braking device.