JP3410339B2 - Electric vehicle braking control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for an electric vehicle that uses both regenerative braking and hydraulic braking, and in particular can appropriately switch from regenerative braking to hydraulic braking before the vehicle stops from a low speed range. It relates to a braking control device.

[0002]

2. Description of the Related Art Recently, in an electric vehicle using an electric motor as a drive source, energy is recovered by operating the electric motor as a generator to charge a battery, and regenerative braking is performed to increase energy when the electric motor is driven. Is being carried out. Since there is a limit to the application of the braking force by the regenerative braking, it is necessary to supplement it by hydraulic braking. For example, as in the braking device for an electric vehicle described in Japanese Patent Laid-Open No. Hei 5-161210, hydraulic braking and regenerative braking are required. Are used together.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the conventional braking control device for an electric vehicle as described in Japanese Patent Publication No. 210, the ratio of regenerative braking and hydraulic braking changes until the vehicle stops from the low speed range. Is appropriate. However, it may be difficult to secure a necessary braking force even if only hydraulic braking is performed by controlling the ratio between regenerative braking and hydraulic braking. In particular, the one provided with the dynamic hydraulic pressure output means for adjusting the output power hydraulic pressure of the auxiliary hydraulic pressure source in accordance with the operation of the brake pedal to output the dynamic hydraulic pressure such as the regulator hydraulic pressure. If the braking is performed only by the output hydraulic pressure of the dynamic hydraulic pressure output means, the wheel cylinder hydraulic pressure may not be increased to a desired pressure within a predetermined time . Therefore, for example, in the case of an electric vehicle that is stopped on a slope, it may be necessary to further press the brake pedal.

In view of the above, the present invention relates to a braking control device for an electric vehicle which uses both regenerative braking and hydraulic braking, and in the low speed range of the vehicle, the hydraulic pressure output by the dynamic hydraulic pressure output means and the static hydraulic pressure output means is used. The subject is to properly perform pressure braking and to reliably maintain a stopped state.

[0005]

In order to achieve the above object, the present invention provides an electric motor connected to a vehicle wheel, a battery mounted on the vehicle, and a rotational drive of the electric motor using the battery as a power source. Then, a motor control means for applying a driving force to the wheels and a braking force for the wheels by regenerative braking of the electric motor, and a brake fluid for a wheel cylinder mounted on the wheels according to an operation of a brake operating member. In a braking control device for an electric vehicle, comprising: a hydraulic pressure control unit that applies a braking force to the wheels by hydraulic braking that supplies a pressure, the hydraulic pressure control unit is configured to operate a reservoir in response to an operation of the brake operation member. Static hydraulic pressure output means for boosting the brake fluid to output static hydraulic pressure, and boosting the brake fluid in the reservoir irrespective of the operation of the brake operating member to obtain a power hydraulic pressure. An auxiliary hydraulic pressure source for outputting, and a dynamic hydraulic pressure output means for adjusting the output power hydraulic pressure of the auxiliary hydraulic pressure source according to the operation of the brake operating member to output a dynamic hydraulic pressure are provided in the electric motor. wherein in response to at the output hydraulic pressure of the hand is also a static pressure generator and the dynamic pressure generator with respect to the wheel cylinders mounted on linked wheel, high-speed run
Regeneration system when the brake operating member is operated while traveling
Hydraulic braking at high speed with motion, and
When operating the brake operating member, regenerative braking and low
A hydraulic pressure detecting means configured to perform hydraulic braking at high speed, and detecting a brake hydraulic pressure of the wheel cylinder and an output hydraulic pressure of the static hydraulic pressure output means,
When shifting to low speed running and performing hydraulic braking at the low speed
In addition to regenerative braking, first, only the dynamic hydraulic pressure output means
Performs hydraulic braking by, the brake fluid pressure of the wheel cylinder on the basis of the detection result of the liquid pressure detecting means, obtains the ratio of the output hydraulic pressure of the static pressure generator, the amount of the component wherein the dynamic hydraulic When a predetermined ratio or more is reached during the hydraulic braking operation by only the output means, the hydraulic braking by the dynamic hydraulic pressure output means only is performed by the dynamic hydraulic pressure output means and the static hydraulic pressure output means. And switching means for switching to.

As the dynamic hydraulic pressure output means, the output hydraulic pressure of the auxiliary hydraulic pressure source is input, and the output hydraulic pressure of the master cylinder, which is the static hydraulic pressure output means, is used as the pilot pressure. It is possible to use a regulator that regulates and outputs hydraulic pressure, or a hydraulic booster that regulates boost hydraulic pressure (regulator hydraulic pressure) and boosts the master cylinder in a similar manner.

In the braking control device, the switching means switches hydraulic braking by only the dynamic hydraulic pressure output means to hydraulic braking by the dynamic hydraulic pressure output means and the static hydraulic pressure output means. After a predetermined time, it may be configured to switch to hydraulic braking by only the static hydraulic pressure output means.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a braking control device for an electric vehicle according to an embodiment of the present invention. The braking control device includes an electric motor 11 that performs regenerative braking and a hydraulic pressure control device that performs hydraulic braking. The latter is a static hydraulic output. A master cylinder 2 as a means,
The regulator 3 as a dynamic hydraulic pressure output means is configured to be driven according to the operation of the brake pedal 5. In FIG. 1, a wheel FR indicates a wheel on the front right side when viewed from the driver's seat, hereinafter a wheel FL indicates a front left side, a wheel RR indicates a rear right side, and a wheel RL indicates a rear left side wheel.
Wheel cylinders 51 to 5 for R, FL, RR, RL
4 is installed. In the present embodiment, a so-called front-rear piping type brake hydraulic system is configured which is divided into a front wheel hydraulic control system and a rear wheel hydraulic control system.

The electric vehicle according to this embodiment has a front wheel F.
R and FL are drive wheels and rear wheels RR and RL are related to so-called front wheel drive of driven wheels, and wheels FR and FL are connected to a drive electric motor 11 via a transmission 12, and this electric motor 11 is The drive is controlled by the electronic control unit 10. The electronic control unit 10 is composed of a motor control microcomputer 10a, which is a motor control means for driving and controlling the electric motor 11, and a hydraulic pressure control microcomputer 10b, which is a hydraulic pressure control means. Since such a structure is similar to that described in, for example, Japanese Patent Application Laid-Open No. 7-336806, description thereof will be omitted.

The electric motor 11 generates a rotating magnetic field by applying AC power to the three-phase windings of the stator,
It is composed of an induction motor that rotationally drives a rotor having a permanent magnet. Therefore, the motor drive circuit (not shown) controlled by the microcomputer 10a is provided with an inverter (not shown). According to this electric motor 11, when the wheels FR and FL are rotating,
By generating a magnetic field in the direction of stopping the rotation by the stator, a braking force can be applied to the rotor and the electromotive force generated in the winding of the stator can be collected in the battery 13. As a result, regenerative braking is performed.

In FIG. 1, the pressure chamber of the master cylinder 2 is connected to the low pressure reservoir 4, and the master cylinder 2
Hydraulic pressure limiting switching device 20 for adding and switching hydraulic braking to regenerative braking in the main hydraulic pressure passage 8 on the front wheel side, which connects the pressure chamber of the vehicle and the wheel cylinders 51, 52 in front of the vehicle.
Is installed. On the other hand, a hydraulic pressure limit switching device 30 is provided in the main hydraulic pressure passage 9 on the rear wheel side, which connects the regulator 3 to each of the wheel cylinders 53 and 54 at the rear of the vehicle. The configuration is slightly different from that of the switching device 20.

An auxiliary hydraulic pressure source 40 is connected to the regulator 3, and these are connected to the low pressure reservoir 4 together with the master cylinder 2. The auxiliary hydraulic pressure source 40 has a hydraulic pump 41 and an accumulator 44. Hydraulic pump 4
1 is driven by an electric motor 42, and a low pressure reservoir 4
This brake fluid is boosted and output, and this brake fluid is supplied to the accumulator 44 via the check valve 43 and the pressure is accumulated.

The electric motor 42 is driven in response to the hydraulic pressure in the accumulator 44 falling below a predetermined lower limit value, and stops in response to the hydraulic pressure in the accumulator 44 exceeding a predetermined upper limit value. . Thus, the so-called power hydraulic pressure is appropriately supplied from the accumulator 44 to the regulator 3. The regulator 3 receives the output hydraulic pressure of the auxiliary hydraulic pressure source 40, uses the output hydraulic pressure of the master cylinder 2 as a pilot pressure, and adjusts the regulator hydraulic pressure proportional to this (a value approximately equal to the master cylinder hydraulic pressure). Since its basic configuration is well known, its explanation is omitted. A part of the regulator hydraulic pressure is used for boosting the master cylinder 2.

As shown in FIG. 1, the hydraulic pressure limit switching device 20 includes a first relief valve 21, a solenoid on-off valve 22, a proportioning valve 23, and a second relief valve 2.
6 are connected in parallel, and further the second relief valve 26
An electromagnetic opening / closing valve 27 is arranged in series. The first relief valve 21 limits the communication of the main hydraulic pressure passage 8 until the output hydraulic pressure of the master cylinder 2 reaches the predetermined pressure Pc, and communicates the main hydraulic pressure passage 8 when the output hydraulic pressure becomes equal to or higher than the predetermined pressure Pc. It is a thing. Further, the second relief valve 26 limits the communication of the main hydraulic pressure passage 8 until the output hydraulic pressure of the master cylinder 2 reaches a predetermined pressure Pb lower than the predetermined pressure Pc, and when the pressure becomes equal to or higher than the predetermined pressure Pb. The main hydraulic passage 8 is communicated with.

The electromagnetic opening / closing valve 22 is an electromagnetic valve which is drive-controlled by the electronic control unit 10 and opens / closes in accordance with the maximum regenerative braking force. The electromagnetic opening / closing valve 27 is also drive-controlled by the electronic control unit 10 to obtain the maximum regenerative braking torque. It is a solenoid valve that opens and closes in response to this, but in particular, it is a solenoid valve that opens and closes in response to the vehicle speed or the maximum regenerative braking torque of the vehicle. The proportioning valve 23 is a hydraulic pressure control valve that controls the output hydraulic pressure of the master cylinder 2 according to the operation of the brake pedal 5 in a predetermined relationship and supplies the hydraulic pressure to the wheel cylinders 51 and 52. Although it has substantially the same configuration as the proportioning valve used for distribution control, the hydraulic pressure at the break point is kept low as described later. The first relief valve 21 (electromagnetic on-off valve 22)
Pressure sensors 24 and 25 are provided on the upstream side and the downstream side, respectively.

On the other hand, the hydraulic pressure limit switching device 30 on the rear wheel side is
The relief valve 31, the electromagnetic opening / closing valve 32, and the proportioning valve 33 are connected in parallel, and although there is no equivalent to the second relief valve 26 and the electromagnetic opening / closing valve 27 described above, they should be provided. May be The relief valve 31 restricts the communication of the main hydraulic pressure passage 9 until the master cylinder hydraulic pressure reaches the predetermined pressure Pc, and connects the main hydraulic pressure passage 9 when the master cylinder hydraulic pressure becomes equal to or higher than the predetermined pressure Pc. The electromagnetic opening / closing valve 32 is the electromagnetic opening / closing valve 22.
Similarly, the main hydraulic passage 9 is opened and closed according to the regenerative braking torque, and the proportioning valve 33 has the same function as the proportioning valve 23.

The first relief valve 21, the electromagnetic opening / closing valve 22 and the proportioning valve 23, which constitute the hydraulic pressure limit switching device 20, have the characteristics shown in FIG. That is, the characteristic of the proportioning valve 23 is that the master cylinder hydraulic pressure increases in accordance with the operation of the brake pedal 5 in the initial stage of the braking operation, and the wheel cylinder hydraulic pressure increases in proportion to this master cylinder hydraulic pressure. When the predetermined pressure Pa is reached, it becomes substantially constant, and even if the master cylinder hydraulic pressure increases, the wheel cylinder hydraulic pressure only slightly increases. The predetermined pressure Pa is set to such a low value that the brake fluid is filled in the wheel cylinders 51 and the like and the brake pads (not shown) come into contact with the rotor (not shown). Thus, the proportioning valve 23 has a function of filling the wheel cylinder with brake fluid at the initial stage of the brake operation,
It has a function of shutting off the hydraulic pressure until the first relief valve 21 operates, and a function of returning the brake fluid from the wheel cylinder 51 or the like to the master cylinder 2.

The characteristics of the first relief valve 21 are shown in FIG.
As indicated by the chain double-dashed line, the master cylinder hydraulic pressure is in a closed state until it reaches a predetermined pressure Pc, and when it exceeds the predetermined pressure Pc, the valve is opened, and thereafter, the wheel cylinder fluid proportional to the master cylinder hydraulic pressure increase. The pressure will increase. The characteristic of the second relief valve 26, as shown by the solid line, is in a closed state until the master cylinder hydraulic pressure reaches a predetermined pressure Pb (Pb <Pc), and opens when it exceeds the predetermined pressure Pb. After this, the wheel cylinder hydraulic pressure increases in proportion to the master cylinder hydraulic pressure increase. Although the electromagnetic opening / closing valve 27 is a valve that controls the operation of the second relief valve 26, the electromagnetic opening / closing valve 22 is in the open position, and the wheel that matches the master cylinder hydraulic pressure as shown by the broken line in FIG. It has the characteristic of cylinder hydraulic pressure. In other words, in FIG. 4, the broken line showing the characteristic of the electromagnetic opening / closing valve 22 and the first relief valve 21 or the second relief valve 21
Relief valve 26 and proportioning valve 2
A region surrounded by a solid line showing the characteristic of No. 3 is a pressure reducing region, and is a range in which regenerative braking is performed instead of hydraulic braking.

As shown in FIG. 1, the brake pedal 5 is provided with a brake switch 6 which is turned on when the brake pedal 5 is depressed, and is connected to the electronic control unit 10 like the pressure sensors 24 and 25. . Further, the shift position of the transmission 12 is detected and the electronic control unit 10
Is supplied with a detection signal. Furthermore, the wheels FR, FL, R
Wheel speed sensors 91 to 94 are provided in R and RL,
These are connected to the electronic control unit 10, and are configured to supply the electronic control unit 10 with a pulse signal having a pulse number proportional to the rotation speed of each wheel, that is, the wheel speed.

Further, a sub-cylinder 70 is interposed in the main hydraulic pressure passage 8 between the hydraulic pressure limit switching device 20 and the wheel cylinders 51, 52. Further, a sub hydraulic pressure passage 9a branches from the main hydraulic pressure passage 9, and a sub cylinder 70 is connected to this. In the sub-cylinder 70, a piston 72 is slidably accommodated in a cylinder 71, and a first pressure chamber 74 and a second pressure chamber 75 are formed on both sides of the cylinder 71 via the piston 72. . A compression spring 73 is accommodated in the second pressure chamber 75, and when the first and second pressure chambers 74, 75 are not hydraulically pressurized, the second pressure chamber 75 has a maximum capacity (hence, The piston 72 is biased to the left in FIG. 1 by the compression spring 73 so that the first pressure chamber 74 has the minimum capacity.

An electromagnetic opening / closing valve 61 is provided in the sub-hydraulic pressure passage 9a connected to the first pressure chamber 74, and a check valve 62 is connected in parallel to the electromagnetic opening / closing valve 61. ing. The solenoid opening / closing valve 61 is a normally closed solenoid valve with two ports and two positions, and is closed when it is not operating, and the first pressure chamber 74 is in the open position when it is operating, and the first pressure chamber 74 is regulated via the auxiliary hydraulic pressure passage 9a. Connect to 3. Therefore, in the sub-cylinder 70, if the electromagnetic opening / closing valve 61 is in the open position, the first pressure chamber 7
4 is applied with a regulator hydraulic pressure (substantially equal to the master cylinder hydraulic pressure) and the second pressure chamber 75 is applied with a wheel cylinder hydraulic pressure, but both pressure chambers are hydraulically separated by a piston 72. There is. When no hydraulic pressure is applied to the first and second pressure chambers 74 and 75,
The piston 72 is at a position where the volume of the first pressure chamber 74 is minimized as shown in FIG.

When the solenoid on-off valve 61 is in the open position and the regulator hydraulic pressure is applied to the first pressure chamber 74 via the solenoid on-off valve 61, the piston 72 moves in a direction to reduce the second pressure chamber 75. Since it is driven, the brake fluid in the second pressure chamber 75 is discharged to the wheel cylinders 51, 52 through the main fluid pressure passage 8 and the pressure is increased. At this time, the wheel cylinder 5
The amount of brake fluid discharged to the first and second pressure chambers 52 is
Since the maximum capacity of 5 is the limit, the wheel cylinder 5
The brake fluid is not excessively supplied to 1,52. Note that the regulator hydraulic pressure may be directly applied to the wheel cylinders 51 and 52 when the electromagnetic opening / closing valve 61 is in the open position without providing the sub-cylinder 70.

Further, although omitted in this embodiment,
Between the sub cylinder 70 and the wheel cylinders 51 and 52, and between the hydraulic pressure limit switching device 30 and the wheel cylinders 5.
It is also possible to interpose a modulator composed of a plurality of electromagnetic valves between the control unit 3 and 54, and to control this by the electronic control unit 10. According to this, not only the anti-skid control but also the traction control, the front-rear braking force distribution control, the braking steering control and the like can be performed by controlling the output hydraulic pressure of the regulator 3 by the modulator.

In the braking controller constructed as described above, the hydraulic pump 41 is driven by the electric motor 42, and the power hydraulic pressure is accumulated in the accumulator 44. When the brake pedal 5 is depressed while each solenoid valve is in the state shown in FIG. 1, the master cylinder 2 outputs the master cylinder hydraulic pressure and the regulator 3 outputs the regulator hydraulic pressure. Then, the electronic control unit 10 performs a series of braking control processes, and while the vehicle is traveling, a program corresponding to the flowcharts of FIGS. 2 and 3 is executed.

In FIG. 2, first, when it is determined in step 101 that an ignition switch (not shown) is turned on, the process proceeds to step 102 and an initial check is performed. Specifically, it is determined based on the detection results of the state of the electric motor 11, the state of the transmission 12, and the state of the battery 13 whether or not the condition for performing regenerative braking is satisfied. For example, when the vehicle is running at an extremely low speed, when the battery is fully charged, when the internal pressure of the battery is high, when there is a failure, or when the vehicle is in the neutral shift position, it is determined that the conditions for performing regenerative braking are not satisfied, and an appropriate alarm is issued.

If the start condition is satisfied, step 103
Then, it is judged whether or not the condition for controlling the hydraulic pressure at the high speed is satisfied, and if the condition is satisfied, the steps 104 and 1 are executed.
In step 05, regenerative braking control and hydraulic pressure control peculiar to high-speed running of the vehicle are performed according to a separate subroutine (not shown), and if they are not satisfied, step 106 is proceeded to. In step 106, it is judged whether or not the condition for controlling the hydraulic pressure at the low speed is satisfied. If the condition is satisfied, the routine proceeds to steps 107 and 108, and when the vehicle is traveling at the low speed according to another subroutine (not shown). Unique regenerative braking control and hydraulic pressure control are performed, and if they are not satisfied, the process directly proceeds to step 109. Then, until it is determined in step 109 that the ignition switch (not shown) is off, the process returns to step 103 and the above control is repeated.

FIG. 3 shows a process common to the regenerative braking control at low speed executed in step 107 of FIG. 2. First, in step 201, it is judged whether or not the brake switch is on. If the brake switch 6 is on, the routine proceeds to step 202, where the shift position of the transmission 12 is judged, and if it is the drive position (D) or the motor brake position (B), the routine proceeds to step 203. The motor brake position (B) is a shift position peculiar to an electric vehicle. In this position, no brake operation is performed, but a state similar to that of engine braking is achieved.

In step 203, the master cylinder hydraulic pressure Pm, which is the detection output of the pressure sensor 24, is changed to the electronic control unit 1.
0 memory. Similarly, in step 204, the wheel cylinder hydraulic pressure Pw which is the detection output of the pressure sensor 25 is stored in the memory of the electronic control unit 10. Subsequently, at step 205, the regenerative braking torque is set according to the control mode during low speed traveling. Then, the routine proceeds to step 206, whether or not hydraulic braking by the output hydraulic pressure of the dynamic hydraulic pressure output means is performed, that is, whether or not the dynamic hydraulic pressure which is the output hydraulic pressure of the regulator 3 is introduced into the sub-cylinder 70. If it is introduced, the routine proceeds to step 207, where the electromagnetic on-off valve 61 is turned on to the open position, and at step 208 the electromagnetic on-off valve 22 is turned on to the closed position. . As a result, the wheel cylinder hydraulic pressure is increased, and hydraulic braking is performed by the output hydraulic pressure of the dynamic hydraulic pressure output means. Then, in step 209, the ratio of the wheel cylinder hydraulic pressure Pw to the master cylinder hydraulic pressure Pm (Pw
It is determined whether / Pm) is equal to or higher than a predetermined ratio Kp (for example, 85%).

When it is determined in step 209 that the wheel cylinder hydraulic pressure Pw is equal to or higher than the predetermined ratio Kp, the routine proceeds to step 210, where switching to hydraulic braking by the output hydraulic pressure of the dynamic hydraulic pressure output means and the static hydraulic pressure output means. Is performed. That is, the electromagnetic opening / closing valve 22 is set to the open position, and the master cylinder 2
To form a bypass hydraulic passage communicating with the wheel cylinders 51, 52. Since the output hydraulic pressure of the master cylinder 2 is also directly supplied to the wheel cylinders 51 and 52, an appropriate braking force is applied to the wheels FR and FL, and the vehicle (not shown) is stopped. If it is, the state is surely retained. The rear wheels RR, RL side electromagnetic on-off valves 32 are controlled in the same manner, but only the front wheels will be described here.

When the elapsed time Ts after the electromagnetic on-off valve 22 is opened is equal to or longer than the predetermined time Ks (for example, 20 ms), the routine proceeds from step 211 to step 212, where the electromagnetic on-off valve 61 is turned off and the closed position. It is said that Therefore, the hydraulic braking is switched only by the output hydraulic pressure of the master cylinder 2, which is the static hydraulic pressure output means. Incidentally, step 20
When NO is determined in 1, 202, 206, 209, 211, the process returns to the main routine of FIG. 2 and the process of the next cycle is performed.

FIG. 5 shows the above-described operation of the present embodiment. The braking operation is performed at point a, regenerative braking is started, and the hydraulic braking is in a standby state (the brake pedal 6 is operated and the master cylinder is operated). The hydraulic pressure and the regulator hydraulic pressure are output, but are not involved in applying the braking force to the wheels). When the vehicle enters the low speed range, b
In order to compensate the regenerative braking torque at the point, the electromagnetic opening / closing valve 61 is set to the open position and hydraulic braking is performed by the regulator hydraulic pressure (via the sub-cylinder 70). This gives 2
The wheel cylinder hydraulic pressure Pw indicated by the dotted line is increased, and a predetermined ratio Kp to the master cylinder hydraulic pressure Pm indicated by the solid line.
As described above, the electromagnetic opening / closing valve 22 is opened at point c, the output hydraulic pressure of the master cylinder 2 is also directly supplied, and hydraulic braking by the master cylinder hydraulic pressure is added. When the state of the electromagnetic opening / closing valve 22 has passed a predetermined time Ts or more, the electromagnetic opening / closing valve 61 is closed and the supply of the regulator hydraulic pressure to the sub-cylinder 70 is stopped. Thereafter, hydraulic braking by only the master cylinder hydraulic pressure is performed. Done.

[0032]

Since the present invention is configured as described above, it has the following effects. That is, in the braking control device for an electric vehicle according to the present invention, the high speed traveling is changed to the low speed traveling.
When performing hydraulic braking at low speed, along with regenerative braking,
First, the hydraulic braking is performed only by the dynamic hydraulic pressure output means, and the ratio of the brake hydraulic pressure of the wheel cylinder to the output hydraulic pressure of the static hydraulic pressure output means is calculated. When the pressure exceeds a predetermined ratio during the pressure braking operation, the hydraulic braking by only the dynamic hydraulic pressure output means is switched to the hydraulic braking by the dynamic hydraulic pressure output means and the static hydraulic pressure output means. Since it is configured, it is possible to appropriately perform hydraulic braking by the output hydraulic pressure of the dynamic hydraulic pressure output means and the static hydraulic pressure output means in the low speed range of the vehicle, and reliably maintain the stopped state even when the vehicle is stopped on a slope. can do.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a braking control process according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a process of regenerative braking control at low speed according to the embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the master cylinder hydraulic pressure and the wheel cylinder hydraulic pressure due to the first and second relief valves, the proportioning valve, and the electromagnetic opening / closing valve according to the embodiment of the present invention.

FIG. 5 is a graph showing changes in motor rotation speed, changes in master cylinder hydraulic pressure and wheel cylinder hydraulic pressure, and an open / closed state of an electromagnetic opening / closing valve according to an embodiment of the present invention.

[Explanation of symbols]

2 master cylinders, 3 regulators 5 brake pedal 10 Electronic control unit 11 electric motor 20, 30 Hydraulic pressure limit switching device 21 First relief valve 22 Solenoid open / close valve 23,33 Proportioning valve 24,25 pressure sensor 26 Second relief valve 27 solenoid valve 32 solenoid valve 40 Auxiliary hydraulic pressure source 51,52,53,54 Wheel cylinder 61 solenoid valve FR, FL, RR, RL wheels

Front Page Continuation (72) Inventor Yoshinori Suzuki 2-1, Asahi-cho, Kariya city, Aichi Aisin Seiki Co., Ltd. (72) Inventor Harumi Ohori 1-cho, Toyota city, Aichi prefecture Toyota Motor Co., Ltd. ( 72) Inventor Shingo Urababa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (56) Reference JP 5-161210 (JP, A) JP 7-336806 (JP, A) JP Flat 7-315186 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B60T 8/00 B60L 7/14 B60L 7/24

Claims (2)

(57) [Claims] 1. An electric motor connected to a wheel of a vehicle, a battery mounted on the vehicle, the electric motor being rotationally driven by using the battery as a power source to apply a driving force to the wheel, and regeneration of the electric motor. Motor control means for applying a braking force to the wheel by braking, and hydraulic braking for applying a brake hydraulic pressure to a wheel cylinder mounted on the wheel according to the operation of a brake operating member, the braking force is applied to the wheel. In a braking control device for an electric vehicle comprising a hydraulic pressure control means, the hydraulic pressure control means boosts the brake fluid in a reservoir according to an operation of the brake operating member to output a static hydraulic pressure. A pressure output means, an auxiliary hydraulic pressure source for increasing the brake fluid in the reservoir to output a power hydraulic pressure regardless of the operation of the brake operating member, and an output power hydraulic pressure of the auxiliary hydraulic pressure source. And a static hydraulic pressure output means for a wheel cylinder mounted on a wheel connected to the electric motor, the dynamic hydraulic pressure output means adjusting pressure according to an operation of the brake operating member to output a dynamic hydraulic pressure. and in accordance with the output liquid pressure of at the hand also of the dynamic pressure generator, a high speed run
Regeneration system when the brake operating member is operated while traveling
Hydraulic braking at high speed with motion, and
When operating the brake operating member, regenerative braking and low
A hydraulic pressure detecting means configured to perform hydraulic braking at high speed, and detecting a brake hydraulic pressure of the wheel cylinder and an output hydraulic pressure of the static hydraulic pressure output means,
When shifting to low speed running and performing hydraulic braking at the low speed
In addition to regenerative braking, first, only the dynamic hydraulic pressure output means
Performs hydraulic braking by, the brake fluid pressure of the wheel cylinder on the basis of the detection result of the liquid pressure detecting means, obtains the ratio of the output hydraulic pressure of the static pressure generator, the amount of the component wherein the dynamic hydraulic When a predetermined ratio or more is reached during the hydraulic braking operation by only the output means, the hydraulic braking by the dynamic hydraulic pressure output means only is performed by the dynamic hydraulic pressure output means and the static hydraulic pressure output means. A braking control device for an electric vehicle, comprising: 2. The switching means switches hydraulic braking by only the dynamic hydraulic pressure output means to hydraulic braking by the dynamic hydraulic pressure output means and the static hydraulic pressure output means, and after a predetermined time. The braking control device for an electric vehicle according to claim 1, wherein the braking control device is configured to switch to hydraulic braking by only the static hydraulic pressure output means.