JP3168180B2 - Electric vehicle braking system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a braking device for an electric vehicle such as an electric vehicle.

[0002]

2. Description of the Related Art In electric vehicles such as electric vehicles, regenerative braking is generally used in order to effectively use electric energy. In a braking device for an electric vehicle that uses such regenerative braking, the braking force is insufficient with regenerative braking alone, so that frictional braking force generated by hydraulic pressure is used in combination to compensate for the lack of braking force. I have. JP 7
JP-A-336806 also discloses an example of a braking device using a friction braking force.

FIG. 3 is a block diagram showing an example of a braking device for an electric vehicle that uses both the regenerative braking force and the friction braking force. In FIG. 3, the brake pedal 10 is connected to a master cylinder 12, and the master cylinder 12 converts a step width of the brake pedal 10 into a hydraulic pressure to generate a static pressure. This master cylinder 1
Reference numeral 2 denotes a static pressure supply source. Master cylinder 1
2 supplies a static pressure to the wheel cylinder 18 of the drive wheel via the pressure reducing valve 14 and the bypass valve 16. Thus, a friction braking force is applied to the drive wheels 22 driven by the motor 20 to compensate for the lack of the regenerative braking force of the motor 20.

FIG. 4A shows the relationship between the master cylinder pressure and the wheel cylinder pressure supplied from the master cylinder 12. That is, indicated by the broken line in the figure,
The pressure actually supplied to the wheel cylinder 18 is lower than the master cylinder pressure by a predetermined value, as compared with the case where the master cylinder pressure and the wheel cylinder pressure have a 1: 1 relationship. As shown in FIG. 4B, the regenerative braking force by the motor 20 is expected to be about 0.2 G. Therefore, the hydraulic pressure is supplied from the master cylinder 12 to the wheel cylinder 18 up to this regenerative braking force. This is because there is no need to use friction braking force together. On the other hand, when the force on the brake pedal 10 increases and the static pressure generated in the master cylinder 12 exceeds 0.2 G, hydraulic pressure is supplied from the master cylinder 12 to the wheel cylinder 18. In this case, the configuration of the pressure reducing valve 14 and the bypass valve 16 results in a hydraulic pressure supply pattern as shown by the solid line in FIG.

[0005] In this case, the regenerative braking force is converted by the conversion means 3.
It is converted to the hydraulic pressure according to the size by 6,
The differential pressure generated between the upstream side and the downstream side of the pressure reducing valve 14 and the bypass valve 16 is obtained from the hydraulic pressure detected by the master cylinder pressure gauge 32 and the wheel cylinder pressure gauge 34, respectively. Thus, the pressure difference between the master cylinder side oil pressure and the wheel cylinder side oil pressure is compared with the oil pressure converted from the regenerative braking force, and the wheel cylinder 18
It is determined whether or not the supply of the hydraulic pressure is required. The hydraulic pressure supplied to the wheel cylinder 18 is measured by the wheel cylinder pressure gauge 3
4 is detected.

When the hydraulic pressure is supplied to the wheel cylinder 18 only from the master cylinder 12, the stroke of the brake pedal 10 varies by the hydraulic pressure. For this reason, the braking feeling may be deteriorated. In order to prevent this, as shown in FIG.
4, the dynamic pressure is supplied to the pressure adjusting means 28 via the pump 26, and the dynamic pressure is supplied from the pressure adjusting means 28 to the wheel cylinder 18 via the hydraulic pressure introducing valve 30. The oil reservoir 24 and the pump 26 constitute a dynamic pressure supply source.

[0007] The pressure adjusting means 28 is adjacent to the master cylinder 12 and changes the dynamic pressure supplied from the pump 26 according to the force on the brake pedal 10.
The pressure is adjusted to be substantially the same as the static pressure generated in step 2. The master cylinder 12, the pump 26, and the pressure adjusting means 28 constitute a hydro booster. In this way, the dynamic pressure adjusted by the pressure adjusting means 28 is supplied to the wheel cylinder 18 via the hydraulic pressure introduction valve 30, so that the shortage of the regenerative braking force of the motor 20 is supplemented by the dynamic pressure. Since there is no need to supply a static pressure from the master cylinder 12, fluctuations in the stroke of the brake pedal 10 can be prevented. Here, a hydro booster, a hydraulic pressure introducing valve 30, a master cylinder side pressure gauge 32,
The wheel cylinder side pressure gauge 34 and the conversion means 36 constitute a dynamic pressure supply means.

[0008]

However, in the above-mentioned conventional braking device, after the hydraulic pressure is supplied to the wheel cylinder 18 from the pressure regulating means 28 constituting the dynamic pressure supplying means via the hydraulic pressure introducing valve 30, the hydraulic pressure introducing valve is used. When the valve 30 was closed, the pressure of the master cylinder 12 constituting the hydro booster picked up the pressure fluctuation from the pressure adjusting means 28, and the static pressure of the master cylinder 12 sometimes fluctuated. For this reason, the pressure difference between the pressure of the wheel cylinder 18 detected by the wheel cylinder side pressure gauge 34 and the static pressure of the master cylinder 12 detected by the master cylinder side pressure gauge 32 increases, and the hydraulic pressure introduction valve is again activated. When 30 is opened, the supply of the hydraulic pressure to the wheel cylinder 18 is re-executed, resulting in a problem that an excessive braking force is generated.

FIG. 5 is an explanatory diagram of this state.
In FIG. 5, when the difference between the pressure of the master cylinder (M / C) 12 and the pressure of the wheel cylinder (W / C) 18 becomes larger than a predetermined value, the opening / closing signal of the hydraulic pressure introduction valve 30 is turned ON. The hydraulic pressure introduction valve 30 is opened and dynamic pressure is introduced into the wheel cylinder 18. As a result, when the pressure of the wheel cylinder 18 increases and the pressure difference between the master cylinder 12 and the wheel cylinder 18 reaches a predetermined value, that is, the pressure of the wheel cylinder 18 and the regenerative braking force converted to the oil pressure by the conversion means 36 The hydraulic pressure introduction valve 30 is closed when the sum of the pressures becomes equal to the pressure of the master cylinder 12. However, when the hydraulic pressure introduction valve 30 is closed, the effect is transmitted to the master cylinder 12 via the pressure adjusting means 28 and appears as a pressure fluctuation of the master cylinder 12. When the pressure of the master cylinder 12 temporarily increases, the difference between the pressure of the master cylinder 12 and the pressure of the wheel cylinder 18 increases,
At this point, the hydraulic pressure introducing valve 30 is opened again to supply dynamic pressure to the wheel cylinder 18. This is the state of erroneous introduction shown in FIG.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a braking device for an electric vehicle which can prevent an excessive braking force from being generated due to a malfunction during dynamic pressure supply. It is in.

[0011]

SUMMARY OF THE INVENTION To achieve the above object, the present invention relates to a braking device for an electric vehicle, and a static pressure supply source for generating a static pressure by converting a pressing force on a brake pedal into a hydraulic pressure. and, and the dynamic pressure source for generating a dynamic pressure, next to the static pressure source
Pressure adjusting means that adjusts the hydraulic pressure of the dynamic pressure supply to be substantially the same as the hydraulic pressure of the static pressure supply according to the force on the brake pedal, and the braking force by the hydraulic pressure of the static pressure supply and the regenerative braking. corresponding anda dynamic pressure supply means for supplying a dynamic pressure from the amount corresponding pressure regulating means to the wheel cylinders of the driving wheels of the difference between the oil pressure after completion dynamic pressure supplied to the wheel cylinders by the dynamic pressure supply means, electrostatic For a predetermined time until the static pressure fluctuation of the pressure supply source is reduced , re-execution of the dynamic pressure supply is prohibited. In the braking device for an electric vehicle, the dynamic pressure
The supply means includes a pressure gauge for measuring the hydraulic pressure of the static pressure supply source, and a
Pressure gauge that measures the oil pressure of the wheel cylinder and regenerative braking force
Is controlled by the output value of the conversion means for converting oil pressure into oil pressure
It is characterized by the following.

[0012]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is an explanatory view showing how dynamic pressure is introduced into the wheel cylinder 18 shown in FIG. 3 in the braking device for an electric vehicle according to the present invention. 1 and 3, as the brake pedal 10 is depressed, the static pressure generated in the master cylinder 12 increases, and the static pressure detected by the master cylinder pressure gauge 32 and the static pressure detected by the wheel cylinder pressure gauge 34 are increased. The difference from the pressure of the wheel cylinder 18 is increased. When this pressure difference becomes a predetermined value, the hydraulic pressure introduction valve opening / closing signal becomes O as in FIG.
N, the hydraulic pressure introducing valve 30 is opened, and dynamic pressure is supplied from the pressure adjusting means 28 to the wheel cylinder 18. With this operation, the pressure of the wheel cylinder 18 increases, and when the difference between the static pressure of the master cylinder 12 and the pressure of the wheel cylinder 18 reaches a predetermined value, the hydraulic pressure introduction valve 30 is closed.

A characteristic point of the present invention is that the hydraulic pressure introducing valve 30 is closed and the pressure regulating means 2 constituting the dynamic pressure supplying means.
8 is to prohibit the introduction of the dynamic pressure for a predetermined time after the supply of the dynamic pressure to the wheel cylinder 18 is completed. In other words, during the dynamic pressure introduction prohibition time, the static pressure of the master cylinder 12 fluctuates, and even when the difference between the static pressure of the master cylinder 12 and the pressure of the wheel cylinder 18 becomes large, the hydraulic pressure introduction valve 30 is also activated. It is prevented that the dynamic pressure supply is re-executed by opening. With such a configuration, the wheel cylinder 18
Does not rise more than necessary, and it is possible to prevent excessive braking force from being generated.

FIG. 2 shows a control flow of the braking device for an electric vehicle according to the present invention. In FIG. 2, it is confirmed whether or not the brake pedal 10 is depressed (S1), and only when the brake pedal 10 is depressed, it is confirmed whether the vehicle is in the traveling mode, that is, the state of the shift lever (S2). . D or B shown in the figure indicates the range of the forward mode. In the braking device for an electric vehicle according to the present invention, the above-described control is performed only when the vehicle is moving forward, and when the vehicle is moving backward, the regenerative braking force is not used and the brake control is entirely performed by hydraulic pressure. Therefore, the above-described prohibition control of the introduction of the dynamic pressure is not performed.

When the position of the shift lever is D or B, since the vehicle is moving forward, as described above,
When the difference between the static pressure of the master cylinder 12 and the pressure of the wheel cylinder 18 increases by a predetermined value or more, the hydraulic pressure introduction valve 30 opens. As a result, the pressure difference between the master cylinder side oil pressure and the wheel cylinder side oil pressure detected by the master cylinder side pressure gauge 32 and the wheel cylinder side pressure gauge 34, respectively, and the regenerative braking force The dynamic pressure is supplied by the amount corresponding to the difference from the hydraulic pressure converted by the conversion means 36. As a result, the pressure of the wheel cylinder 18 increases. Next, when the pressure difference between the static pressure of the master cylinder 12 and the pressure of the wheel cylinder 18 decreases, the hydraulic pressure introduction valve 30 closes,
Thereafter, the operation of introducing the dynamic pressure is prohibited for a certain period of time (S3).

After a lapse of a predetermined time in S3, normal dynamic pressure introduction control is performed, and the master cylinder 1
2 and the pressure of the wheel cylinder 18,
The necessity of supply of dynamic pressure is determined, and if necessary, the hydraulic introduction valve 3
0 is opened (S4). Through the above steps, the control of the braking device for the electric vehicle according to the present invention is executed.

[0018]

As described above, according to the present invention,
Since the introduction of dynamic pressure is prohibited for a predetermined time after the introduction of dynamic pressure to the wheel cylinder is completed and the hydraulic pressure introduction valve is closed, malfunction of dynamic pressure introduction due to pressure fluctuation of the master cylinder is prevented. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of control of introduction of dynamic pressure to a wheel cylinder in a braking device for an electric vehicle according to the present invention.

FIG. 2 is a diagram showing a control flow of the braking device for the electric vehicle according to the present invention.

FIG. 3 is a block diagram of an example of an electric vehicle braking device that uses both a regenerative braking force and a friction braking force.

FIG. 4 is an explanatory view of a conventional pattern of hydraulic pressure supply from a master cylinder to a wheel cylinder.

FIG. 5 is an explanatory diagram showing control during supply of dynamic pressure in a conventional braking device for an electric vehicle.

[Explanation of symbols]

10 brake pedal, 12 master cylinder, 14
Pressure reducing valve, 16 bypass valve, 18 wheel cylinder, 20 motor, 22 drive wheel, 24 oil reservoir, 26 pump, 28 pressure regulating means, 30 hydraulic pressure introducing valve, 32 master cylinder side pressure gauge, 34 wheel cylinder side pressure gauge, 36 Conversion means.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tetsuya Kuno 2-1-1 Asahicho, Kariya-shi, Aichi Aisin Seiki Co., Ltd. (72) Inventor Tadashi Tazawa 2-1-1 Asahicho, Kariya-shi, Aichi Aisin Seiki (56) References JP-A-7-336806 (JP, A) JP-A-6-153312 (JP, A) JP-A-3-90864 (JP, A) JP-A-6-304885 (JP, A) A) Actually open 1983-19312 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/00 B60L 7/24

Claims (2)

(57) [Claims] 1. A static pressure supply source for generating a static pressure by converting a pressing force of a brake pedal into a hydraulic pressure, a dynamic pressure supply source for generating a dynamic pressure, and being arranged adjacent to the static pressure supply source, The blur
Pressure adjusting means for adjusting the hydraulic pressure of the dynamic pressure supply source to substantially the same as the hydraulic pressure of the static pressure supply source in accordance with the force applied to the brake pedal; and And a dynamic pressure supply means for supplying dynamic pressure from the pressure adjustment means to a wheel cylinder of a drive wheel by an amount corresponding to the difference between the static pressure and the dynamic pressure after the dynamic pressure supply means completes the supply of dynamic pressure to the wheel cylinder. A braking device for an electric vehicle, wherein the re-execution of the dynamic pressure supply is prohibited for a predetermined time until the static pressure fluctuation of the supply source is reduced . 2. The electric vehicle braking device according to claim 1,
And the dynamic pressure supply means measures the hydraulic pressure of the static pressure supply source.
Pressure gauge to measure the oil pressure of the wheel cylinder.
Pressure gauge, and a conversion means for converting regenerative braking force to hydraulic pressure.
Control of an electric vehicle characterized by being controlled by an output value
Motion device.