JPH05176407A - Brake controller for electric automobile - Google Patents

Abstract

PURPOSE:To enhance brake feeling while optimizing distribution of brake force between front and rear wheels. CONSTITUTION:Front wheels 10 are subjected to regenerative and hydraulic brake whereas rear wheels are subjected to hydraulic brake. Hydraulic pressure of a brake master cylinder 20 is interrupted by means of a reducing valve 30 and regenerative braking is performed depending on the differential pressure DELTAP across the reducing valve 30 at the time of interruption. At the same time, a stroke simulator 38 simulates oil consumption of a front brake 26 thus eliminating strange feeling of brake stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle equipped with hydraulic braking means and regenerative braking means, and more particularly to a braking control device having means for improving brake feeling.

[0002]

2. Description of the Related Art An electric vehicle is a vehicle having a motor as a drive source, and its braking device includes, for example, a hydraulic brake such as a hydraulic brake, and a regenerative brake using a primary current control of the motor.

Hydraulic brakes are a widely used braking means in other types of vehicles. That is, it is a brake that brakes the wheels by generating hydraulic pressure in response to the depression of the brake pedal and transmitting this hydraulic pressure via piping. Since this brake mechanically brakes the wheels by the hydraulic pressure to be transmitted, it can be used regardless of whether the wheels are driving wheels or not.

The regenerative brake is based on the principle of regenerating the traveling motor, and therefore includes vehicles that use the motor for traveling (normal electric vehicles as well as vehicles such as hybrid vehicles that also include an engine). ) Will be installed exclusively. For example, when the induction motor is used as a traveling motor, the required output torque can be obtained by controlling the primary current of the induction motor. This control is performed by, for example, a PWM control of the inverter circuit and vector control of the primary current. Regenerative braking is
It is realized as a part of this torque control, that is, by controlling the primary current so that the motor operates as a generator and a regenerative torque is obtained. Therefore, the regenerative brake
This is a brake that exclusively brakes the drive wheels.

When both the hydraulic brake and the regenerative brake are used, it is necessary to adjust the braking force distribution between the driving wheels and the non-driving wheels. For example, in a vehicle having front wheels as driving wheels and rear wheels as non-driving wheels, consider a configuration in which the front wheels are braked by hydraulic brakes and regenerative brakes, and the rear wheels are braked by hydraulic brakes. In this configuration, the braking force applied to the front wheel becomes larger than the braking force applied to the rear wheel by the amount of the regenerative braking force.

In view of such a point, a configuration has been already proposed in which the front / rear braking force distribution is improved and the electric vehicle is smoothly braked (Actual No. Sho 63-29).
No. 301). In this conventional technique, for example, a front wheel that is a driving wheel is braked by a regenerative brake, and a rear wheel that is a non-driving wheel is braked by a hydraulic brake. Furthermore, the hydraulic pressure is changed to optimize the distribution of front and rear braking forces. As a result, the motor can be efficiently regenerated, and the travelable distance per charge of the battery becomes long.

[0007]

However, if the braking force is adjusted by changing the hydraulic pressure, the distribution of the braking force can be optimized and, for example, the front wheel can be prevented from being locked early, but on the other hand, the braking force is reduced. The stroke of the pedal changes and the brake feel deteriorates.

The present invention has been made to solve the above problems, and an object thereof is to improve the brake feeling while realizing the optimum distribution of the braking force.

[0009]

In order to achieve such an object, the present invention provides a hydraulic braking system in which hydraulic pressure is generated in response to depression of a brake pedal to mechanically brake a driving wheel and a non-driving wheel. And a regenerative braking means for braking the drive wheels by regeneration of the traveling motor, in a braking device for an electric vehicle, the hydraulic braking means being provided on a hydraulic pressure transmission path from the hydraulic braking means to the drive wheels. And a shut-off means for shutting off the hydraulic pressure generated under the predetermined condition, and when the hydraulic pressure is shut off by the shut-off means, a fluid amount corresponding to the shut-off hydraulic pressure is consumed on the hydraulic braking means side of the shut-off means. Liquid consumption means, a differential pressure detection means for detecting the differential pressure generated before and after the shutoff means by shutting off, and a regenerative torque command value is obtained according to the detected differential pressure, and regenerative braking is performed based on this regenerative torque command value. Control controlling means Characterized in that it comprises a stage, a.

[0010]

In the braking control device of the present invention, the non-driving wheels are mechanically braked by the hydraulic braking means in response to the depression of the brake pedal, and the driving wheels are braked by the hydraulic braking means and the regenerative braking means.

In braking the driving wheels, for example, when the brake pedal is shallowly depressed and the hydraulic pressure generated in the hydraulic braking means is low, this hydraulic pressure is cut off by the cutoff means. When the hydraulic pressure is shut off, a differential pressure is generated across the shutoff means. In the present invention, the regenerative braking force is generated by the amount corresponding to the differential pressure due to the interruption. That is, the differential pressure detection means detects the differential pressure, the control means determines the regenerative torque command value in accordance with the detected differential pressure, and the regenerative braking means is controlled based on the regenerative torque command value.

As described above, the braking of the non-driving wheels is performed by the hydraulic braking force according to the depression of the brake pedal, and the braking of the driving wheels is performed by the regenerative braking force (at the time of interruption) or the regeneration according to the depression of the brake pedal. And hydraulic braking force (when opened). Therefore, by adjusting the regenerative braking force, the braking force distribution is optimized, for example, the front wheel is prevented from being locked early.

On the other hand, when the hydraulic pressure is shut off by the shut-off means, the amount of fluid consumed on the drive wheel side is reduced. In order to cover this reduction in the liquid consumption and to prevent the total liquid consumption viewed from the hydraulic braking means from being related to the operation / non-operation of the shutoff means, the liquid consumption means is provided in the present invention. ..
The fluid consumption means consumes the fluid volume corresponding to the shutoff fluid pressure on the fluid pressure braking means side of the shutoff means. As a result, the brake feeling is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an electric vehicle equipped with a braking control device according to a first embodiment of the present invention.

The electric vehicle shown in this figure uses front wheels 10 as driving wheels and rear wheels (not shown).
Is a non-driving wheel. That is, the front wheel 10 is connected to the motor 14 via the transmission 12.
Driven by. The motor 14 outputs a required torque under the control of the ECU 16.

For example, when an induction motor is used as the motor 14, a DC voltage output from a battery (not shown) is converted into an AC current by an inverter circuit, and the AC current drives the motor. At this time, by performing PWM control of the switching element forming the inverter circuit, the AC current to be output can be vector-controlled, and the output torque of the motor can be controlled.

The braking of the front wheel 10 by the regeneration of the motor 14 is executed as such torque control. The motor 14 has a regenerative characteristic as shown in FIG. 2B, and can generate a regenerative torque (regenerative braking force) as shown in this figure according to the number of revolutions.

The electric vehicle shown in FIG. 1 is equipped with a hydraulic brake in addition to such a regenerative brake. That is, the brake master cylinder 20 that generates a hydraulic pressure according to the depression amount of the brake pedal 18 is provided, and the hydraulic pressure generated in the brake master cylinder 20 is a front brake provided on the front wheel 10 via the pipes 22 and 24. 26 to the rear wheels via pipes 28, respectively. Therefore, the device of the present embodiment has a configuration in which the front wheel 10, which is a driving wheel, is regeneratively braked and hydraulically braked, and the rear wheel, which is a non-driving wheel, is hydraulically braked.

Further, in this embodiment, in order to optimize the distribution of the braking force between the front / rear wheels, means for interrupting the hydraulic pressure is provided between the pipes 22 and 24. Further, there is provided a means for simulating the amount of oil consumed when the hydraulic pressure is cut off to improve the brake feeling. These means have a configuration according to the features of this embodiment.

First, a pressure reducing valve 30 is provided as means for cutting off the hydraulic pressure. The pressure reducing valve 30 includes the pipes 22 and 2
4, the pressure difference between the two pipes 22 and 24 is set to a certain value, that is, the hydraulic pressure is cut off when the value is equal to or less than the valve opening value.
When the valve open value is exceeded, the hydraulic pressure is transmitted by opening the valve. Further, a solenoid valve 32 is provided to enable communication between the pipes 22 and 24 even when the pressure difference ΔP is equal to or less than the valve opening value and the pressure reducing valve 30 is closed. That is, when the solenoid valve 32 is turned on, hydraulic pressure is transmitted to the pipes 22 to 24 regardless of the differential pressure ΔP, and the front wheel 10 is hydraulically braked. Further, a check valve 34 is provided in parallel with the pressure reducing valve 30 for holding the differential pressure ΔP, and a hydraulic pressure sensor 36 for detecting the differential pressure ΔP for enabling adjustment of the regenerative braking force according to the differential pressure ΔP. Is provided.

A stroke simulator 38 is provided on the brake master cylinder 20 side as seen from the pressure reducing valve 30 as means for simulating the amount of oil consumption and improving the brake feeling when the hydraulic pressure is cut off. ing. When the hydraulic pressure is shut off by the pressure reducing valve 30, the stroke simulator 38 consumes the amount of oil in the brake master cylinder 20 in a form similar to that of the front brake 26. The maximum oil consumption of the stroke simulator 38 is set according to the valve opening value of the pressure reducing valve 30, and when the pressure reducing valve 30 opens, the oil consumption of the stroke simulator 38 becomes maximum.

The operation of this embodiment is shown in FIG. In particular, FIG. 2A shows a control flowchart of the ECU 16, and FIG. 2B shows points at which the solenoid valve 32 is turned on / off.

As shown in FIG. 2 (a), the ECU 16
Determines whether the brake pedal 18 is depressed by the stop lamp switch 40 (100). When the brake pedal 18 is not depressed, the ECU 16 turns off the solenoid valve 32 (102), and the pressure reducing valve 30
Thus, the pipes 22 and 24 are cut off from each other. Further, the ECU 16 sets the regenerative torque command value for the motor 14 to 0 (104). Therefore, in this case, the braking force is not applied to the front wheel 10 and the rear wheel.

When the stop lamp switch 40 detects that the brake pedal 18 is stepped on, the ECU
16 determines whether or not the rotation speed of the motor 14 exceeds ω ₁ (106). When the rotation speed of the motor 14 detected by a rotation sensor (not shown) exceeds ω ₁ ,
The ECU 16 turns off the solenoid valve 32 (1
08). At this time, if the differential pressure ΔP is small and does not exceed the valve opening value of the pressure reducing valve 30, the pressure reducing valve 30 remains closed. On the contrary, if the differential pressure ΔP is large and exceeds the opening value of the pressure reducing valve 30, the pressure reducing valve 30 is opened and the pipes 22 to 24 are connected.
The hydraulic pressure can be transmitted to.

At the next step 110, the ECU 16
A regenerative torque command value is calculated based on the differential pressure ΔP detected by the hydraulic pressure sensor 36. Further, the calculated regenerative torque command value is output to the motor 14 (more specifically, to an inverter circuit (not shown)) (112).

At this time, if the differential pressure ΔP is small and the hydraulic pressure is shut off by the pressure reducing valve 30, the hydraulic pressure of the brake master cylinder 20 is not transmitted to the front brake 26, the front wheel 10 is only regeneratively braked, and the rear wheel is It is braked only by the hydraulic brake. On the contrary, if the differential pressure ΔP is large and the hydraulic pressure can be transmitted to the pipes 22 to 24, both the front wheel 10 and the rear wheel are braked by the hydraulic brake. Further, since the differential pressure ΔP is held by the check valve 34, the front wheel 10 is also braked by the regenerative brake.

In step 106, the motor 1
When the rotation speed of 4 does not exceed ω ₁ , the solenoid valve 32 is turned on (114) and hydraulic pressure can be transmitted between the pipes 22 and 24. ω ₁ is the lower limit value of the constant value region of the motor regenerative braking force, as shown in FIG. When the rotation speed of the motor 14 does not exceed ω ₁ ,
Since the regenerative braking force is not large enough, hydraulic braking force is used.

After steps 104, 112 and 114, the process returns to step 100 and the above operation is repeated.

Next, regarding the operation described above and the operation of the stroke simulator 38 according to the features of the present embodiment,
The operation will be described in accordance with the operation of the brake pedal by the operator.

First, when the driver starts stepping on the brake pedal 18, this is detected by the stop lamp switch 40, and the ECU 16 performs braking control according to the rotation speed of the motor 14. During normal traveling, the rotational speed of the motor 14 exceeds ω ₁ , so the solenoid valve 32 is turned off.

When the brake pedal 18 is shallowly depressed, the differential pressure ΔP is small, and therefore the pressure reducing valve 30 shuts off the connection between the pipes 22 and 24. In this state, EC
U16 calculates the regenerative torque command value according to the differential pressure ΔP detected by the hydraulic sensor 36, and brakes the front wheel 10 only by the regenerative brake. In this case, the front / rear braking force distribution can be optimized by controlling the regenerative braking force.

However, since the hydraulic pressure is shut off by the pressure reducing valve 30, the amount of oil that should be consumed in the front brake 26 may remain unconsumed. The stroke simulator 38 realizes a pedal stroke with no discomfort, that is, a good brake feeling, by consuming the amount of oil that should be consumed in the front brake 26.

When the brake pedal 18 is further depressed, the pressure difference ΔP between the pipes 22 and 24 exceeds the set value of the pressure reducing valve 30 at some point. Then, the pressure reducing valve 30 opens, and the hydraulic pressure is applied to the front brake 26. Therefore, in this state, the front wheel 10 is braked by the hydraulic pressure.
Further, the stroke simulator 38 is set so as to perform bottoming when the pressure reducing valve 30 opens (that is, the consumed oil amount reaches the maximum value, and the oil amount cannot be consumed any more). For example, when the pressure reducing valve 30 opens at 10 atmospheres, the stroke simulator 38 is also set to bottom at 10 atmospheres. Further, in this state, the differential pressure ΔP
Is held by the check valve 34, and
The regenerative braking force corresponding to the held differential pressure ΔP is also applied to the front wheel 10.

After that, when the operator releases the brake pedal 18, the differential pressure Δ held by the check valve 34 is changed.
P decreases. Therefore, the regenerative braking force also decreases. When the differential pressure ΔP decreases and reaches 0, the hydraulic pressure applied to the front brake 10 via the check valve 34 decreases, and the hydraulic braking force decreases.

Immediately before the vehicle stops due to such braking, the number of revolutions of the motor 14 decreases, and as a result, the regenerative braking force decreases (see FIG. 2B). That is, when the number of rotations of the motor 14 falls below ω ₁ which is the boundary at which the regenerative braking force decreases, the braking force applied to the front wheel 10 becomes substantially only the hydraulic braking force.

In this embodiment, steps 106 and 114 are executed as a countermeasure against such a case. That is, when the rotation speed of the motor 14 falls below ω ₁ which is the boundary at which the regenerative braking force decreases, the pipes 22 and 24 are directly connected,
The hydraulic pressure of the master brake cylinder 20 is applied to the front brake 26 as it is. As a result, even when the vehicle approaches a stop and the rotation speed of the motor 14 is reduced, sufficient braking force can be obtained by the hydraulic pressure. This operation is particularly effective when the vehicle is stopped on a slope. After the vehicle is stopped and the brake pedal 18 is not depressed,
The solenoid valve 32 is turned off, and the pressure reducing valve 30 returns to a state where the hydraulic pressure is shut off.

As described above, according to this embodiment, the front / rear braking force distribution is optimized and the front wheel 1
It is possible to prevent early locking of 0 and the like, and since the stroke simulator 38 simulates the oil consumption of the front brake 26, the brake stroke does not feel uncomfortable and the brake feeling is improved.

FIG. 3 shows a schematic structure of an electric vehicle equipped with a braking control device according to a second embodiment of the present invention. In this embodiment, the pressure reducing valve 4 is added to the structure of the first embodiment.
2, solenoid valve 44, stroke simulator 4
6 is added.

The solenoid valve 44 is provided so that the pressure reducing valve 42 is interposed between the pressure reducing valve 30 and the pipe 24 when it is on, and the pressure reducing valve 30 and the pipe 24 are directly connected when it is off. ing. Further, the stroke simulator 46 is set to perform bottoming with the same amount of oil as the stroke simulator 38, and simulates the amount of oil consumed by the front brake 26 when the hydraulic pressure is shut off by the pressure reducing valve 42.

In this embodiment, attention is paid to the fact that the regenerative braking force of the motor 14 decreases in the high rotation range of the motor 14. As shown in FIG. 4B, the regenerative braking force of the motor 14 starts to decrease as the rotation speed increases. Therefore, the regenerative braking force becomes smaller at high speed (FIG. 5A) than at low speed (FIG. 5B).
In the present embodiment, paying attention to this change, the hydraulic braking force related to the front wheel 10 is more precisely controlled in the high rotation region where the regenerative braking force decreases.

The operation of this embodiment is shown in FIG. In particular, FIG. 4A shows a control flowchart of the ECU 16, and FIG. 4B shows points at which the solenoid valves 32 and 44 are turned on / off.

As shown in FIG. 4 (a), the ECU 16
First executes step 100 as in the first embodiment.
If the brake pedal 18 is not depressed, the ECU
16 turns off the solenoid valves 32 and 44 (11
6) The pressure reducing valve 30 blocks the pipes 22 and 24. Further, after executing step 104, the process returns to step 100. Therefore, in this case, the present embodiment has substantially the same functional configuration as the first embodiment.

When the stop lamp switch 40 detects that the brake pedal 18 is stepped on, the ECU
Reference numeral 16 determines whether the rotation speed of the motor 14 detected by a rotation sensor (not shown) exceeds ω ₂ (1
18). As shown in FIG. 4B, ω ₂ is set near the boundary with the high rotation speed region where the regenerative braking force starts to decrease.

When the rotation speed of the motor 14 exceeds ω ₂ , the ECU 16 turns off the solenoid valves 32 and 44 (120). In this state, the pressure reducing valve 30 is interposed between the pipes 22 and 24 as in the case of executing step 106 in the first embodiment.

In this embodiment, the valve opening value of the pressure reducing valve 30 is set to the pressure corresponding to a in FIG. 4 (b). The stroke simulator 38 bottoms at the valve opening value of the pressure reducing valve 30. Further, the pressure reducing valve 42 provided in this embodiment is opened by the hydraulic pressure corresponding to b in FIG. 4 (b). The stroke simulator 46 bottoms at the valve opening value of the pressure reducing valve 42.

Therefore, if the differential pressure ΔP is equal to or less than the regenerative braking force a when step 120 is executed, the pressure reducing valve 30 remains closed and the brake master cylinder 2
The oil pressure of 0 is cut off. If the differential pressure ΔP exceeds the amount corresponding to the regenerative braking force a, the pressure reducing valve 30 is opened,
The hydraulic pressure can be transmitted to the pipes 22 to 24. After execution of step 120, step 110 as in the first embodiment.
And 112, and returns to step 100.

In step 118, the motor 1
If 4 of the rotational speed does not exceed the omega _2, the rotation speed of the motor 14 it is determined whether it is ₁ or more omega less than ₂ omega is performed (122). If this condition is met, the solenoid valve 32 is turned off and the solenoid valve 44 is turned on (124). That is, the pressure reducing valves 30 and 42 are both interposed between the pipes 22 and 24.

Therefore, if the differential pressure ΔP is equal to or less than the regenerative braking force b when step 124 is executed, the pressure reducing valves 30 and 42 shut off the hydraulic pressure in the brake master cylinder 20. If the differential pressure ΔP exceeds the amount corresponding to the regenerative braking force b, the pressure reducing valves 30 and 42 are opened,
The hydraulic pressure can be transmitted to the pipes 22 to 24.

After executing step 124, step 110
And 126, calculation of regenerative torque command value (126)
And its output (128). Then, the process returns to step 100.

When it is determined in step 122 that the condition is not satisfied, the motor 14 is used as in the case where it is determined that the condition is not satisfied in step 106 of the first embodiment.
The rotation speed of is low and sufficient regenerative braking force cannot be obtained.
Therefore, in order to brake the front wheel 10 by the hydraulic braking force, the solenoid valve 32 is turned on, the solenoid valve 44 is turned off, and the pipes 22 and 24 are directly connected (130). Then, the process returns to step 100.

Next, the operation described above and the operations of the stroke simulators 38 and 46 according to the features of this embodiment will be described in accordance with the operation of the brake pedal by the operator.

First, when the driver starts to depress the brake pedal 18, this is detected by the stop lamp switch 40, and the ECU 16 controls the braking according to the rotation speed of the motor 14.

When the rotation speed of the motor 14 exceeds ω ₂ which is determined by a sensory test of the vehicle or the like, the solenoid valves 32 and 44 are turned off at a high speed. At this time, if the brake pedal 18 is shallowly depressed, the differential pressure ΔP is small, so that the pressure reducing valve 30 closes the connection between the pipes 22 and 24, as in the normal running of the first embodiment. The ECU 16 calculates a regenerative torque command value according to the differential pressure ΔP detected by the hydraulic pressure sensor 36, and brakes the front wheel 10 only by the regenerative brake. As a result, the braking force distribution can be optimized, and the stroke simulator 38 is set to perform bottoming by the amount equivalent to the regenerative braking force a.
Thus, as in the first embodiment, a good brake feeling is realized.

When the brake pedal 18 is further depressed while the vehicle remains at high speed, the differential pressure ΔP exceeds the opening value of the pressure reducing valve 30. Then, the pressure reducing valve 30 opens, and the hydraulic pressure is applied to the front brake 26. Further, the regenerative braking force is applied by the differential pressure ΔP held by the check valve 34.

When the vehicle has a low speed (the rotation speed of the motor 14 is ω ₁ or more and less than ω ₂ ) due to such braking, or when braking is performed from a low speed running state, the solenoid valve 32 is turned off and the solenoid valve 32 is turned off. 44 is turned on. At this time, if the brake pedal 18 is shallowly depressed, the differential pressure ΔP is small, so that the pressure reducing valves 30 and 42 disconnect the pipes 22 and 24. The ECU 16 calculates a regenerative torque command value according to the differential pressure ΔP detected by the hydraulic pressure sensor 36, and brakes the front wheel 10 only by the regenerative brake.

The regenerative braking force at this time can be made larger than that at high speed. That is, if only the pressure reducing valve 30 is used, the disconnection between the pipes 22 and 24 is opened by the differential pressure ΔP equivalent to the regenerative braking force a, but at the low speed using the pressure reducing valves 30 and 42, the regenerative braking force b> a is equivalent. Not released up to the differential pressure ΔP. Therefore, the front wheel 10 is braked by the regenerative braking force of a or more and less than b.

At low speed, when the brake pedal 18 is further depressed and the differential pressure ΔP exceeds a value that can be shut off by the pressure reducing valves 30 and 44, the pressure reducing valves 30 and 42 are opened,
Hydraulic pressure is applied to the front brake 26. Further, the regenerative braking force is applied by the differential pressure ΔP held by the check valve 34.

Comparing the operation at low speed with the operation at high speed, it can be seen that the hydraulic braking force increases at high speed. That is, since the hydraulic pressure is shut off only by the pressure reducing valve 30 at a high speed, the hydraulic brake starts to operate and the differential pressure ΔP is low, and the hydraulic brake starts to operate when the depression amount of the brake pedal 18 is relatively small. At low speeds, the hydraulic pressure is cut off by the pressure reducing valves 30 and 42, and therefore the differential pressure ΔP at which the hydraulic brake starts to operate is high, and the hydraulic brake does not start to operate unless the depression amount of the brake pedal 18 becomes relatively large. Therefore, the imbalance between low speed and high speed as shown in FIG. 5 is corrected.

In addition, the operator operates the brake pedal 18
Is returned, and the operation when the rotation speed of the motor 14 is lower than ω ₁ is almost the same as in the first embodiment.

As described above, according to this embodiment, as in the first embodiment, the front / rear braking force distribution can be optimized to prevent the front wheel 10 from being locked early. Further, the imbalance between high speed and low speed can be reduced. Further, the stroke simulators 38 and 46 eliminate the discomfort in the brake stroke and improve the brake feeling.

Although the above description is for a normal electric vehicle, the present invention can be applied to a hybrid vehicle equipped with an engine as well as a motor.

[0062]

As described above, according to the present invention,
Since the hydraulic pressure of the hydraulic braking means is cut off and the regenerative braking is performed according to the differential pressure, the braking force distribution is optimized, and the hydraulic quantity consumption means consumes the hydraulic quantity related to the cutoff. The pedal stroke is stable and the brake feeling is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a braking control device for an electric vehicle according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the operation of the first embodiment, and FIG.
2 is a control flowchart of the ECU, and FIG. 2B is a diagram showing a regeneration characteristic of the motor and a switching point of hydraulic pressure supply to the front brake.

FIG. 3 is a block diagram showing a configuration of a braking control device for an electric vehicle according to a second embodiment of the present invention.

FIG. 4 is a diagram showing the operation of the second embodiment, and FIG.
FIG. 4 is a control flowchart of the ECU, and FIG. 4B is a diagram showing regeneration characteristics of the motor and switching points of hydraulic pressure supply to the front brake.

FIG. 5 is a diagram showing a braking force imbalance at high speed and low speed of the motor when both regenerative braking and hydraulic braking are used.

[Explanation of symbols]

 10 Front Wheel 14 Motor 16 ECU 18 Brake Pedal 20 Brake Master Cylinder 22, 24, 28 Piping 26 Front Brake 30,42 Pressure Reduction Valve 32,44 Solenoid Valve 34 Check Valve 36 Hydraulic Sensor 38,46 Stroke Simulator 40 Stop Lamp Switch ΔP Difference Pressure

Claims (1)

[Claims] 1. A hydraulic braking means for mechanically braking a driving wheel and a non-driving wheel by generating a hydraulic pressure in response to depression of a brake pedal, and a regenerative braking means for braking the driving wheel by regeneration of a traveling motor. A braking device for an electric vehicle including: a shutoff means provided on a hydraulic pressure transmission path from the hydraulic braking means to the drive wheels, and shutting off the hydraulic pressure generated in the hydraulic braking means under predetermined conditions; When the hydraulic pressure is shut off by the liquid pressure consuming means that consumes the amount of fluid corresponding to the shut off hydraulic pressure on the hydraulic braking means side of the shutoff means, and the differential pressure generated before and after the shutoff means An electric vehicle characterized by comprising: a differential pressure detecting means for detecting; a regenerative torque command value obtained according to the detected differential pressure; and a control means for controlling the regenerative braking means based on the regenerative torque command value. Braking control device .