JP2005014692A - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device stabilizing braking effect and reducing loads on a brake pad by varying distribution between an regenerative braking amount and a hydraulic braking amount based on the temperature of the brake pad. <P>SOLUTION: A detection value by a pedal stepping quantity detecting sensor 24 is read, and target deceleration is set by an ECU 20. Then, the temperature of the brake pad which is a brake friction material constituting each wheel brake B<SB>FL</SB>, B<SB>FR</SB>, B<SB>RL</SB>, B<SB>RR</SB>is estimated, the regenerative braking amount by a regenerative brake and the hydraulic braking amount by a hydraulic brake are distributed based on the estimated temperature of the brake pad, and the regenerative brake and the hydraulic brake are controlled based on the target deceleration, and the distributed regenerative and hydraulic braking amount and the hydraulic braking amount distributed among the front and rear wheels. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a brake control device that controls a regenerative brake by a traveling motor and a hydraulic brake that is a mechanical brake.
[0002]
[Prior art]
Conventionally, in an electric vehicle or a hybrid vehicle that uses a motor as a drive source, a regenerative brake that recovers kinetic energy lost during braking has been adopted in order to improve energy efficiency by using the motor as a generator during deceleration. . Such electric vehicles and hybrid vehicles are equipped with a hydraulic brake that is a mechanical brake that operates by the pressure of the working fluid in response to depression of the brake pedal, and braking is performed by cooperation between the hydraulic brake and the regenerative brake. It has been broken.
[0003]
In automobiles where braking is performed by cooperation between mechanical brakes and regenerative brakes, the presence or absence of an abnormality in the motor is detected, and when an abnormality occurs in the motor, braking corresponding to the depression of the brake pedal only by the mechanical brake There is an automobile braking device that performs the above in a responsive manner (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-61203
[Problems to be solved by the invention]
By the way, in an automobile in which braking is performed by cooperation between a hydraulic brake and a regenerative brake, in general, braking by the hydraulic brake and the regenerative brake is performed based on a preset distribution value (ratio). Yes. In other words, braking is performed at a preset distribution ratio without considering the state of the brake pads constituting the hydraulic brake. Therefore, even for brake pads that become less effective at low temperatures or become heavily worn at high temperatures, braking is performed with a distribution ratio based on a constant temperature, so the brake effectiveness becomes unstable. Or the brake pads are aging faster.
[0006]
The subject of this invention is providing the brake control apparatus which changes distribution of the amount of regenerative brakes, and the amount of hydraulic brakes based on the temperature of a brake pad, and implement | achieves the stable brake performance.
[0007]
[Means for Solving the Problems]
The brake control device according to claim 1 is a brake control device that controls a regenerative brake by a travel motor for vehicle travel and a hydraulic brake that is a mechanical brake device, based on a depression amount of a brake pedal. Based on the estimated temperature of the brake pad estimated by the temperature estimating means, the temperature estimating means for estimating the temperature of the brake pad that constitutes the hydraulic brake, The brake amount distribution means for distributing the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake, the target deceleration set by the target deceleration setting means, and the regeneration distributed by the brake amount distribution means Brake control means for controlling the regenerative brake and hydraulic brake based on the brake amount and hydraulic brake amount Characterized in that it comprises a.
[0008]
According to the brake control device of the first aspect, since the distribution between the regenerative brake amount and the hydraulic brake amount is optimally performed based on the temperature of the brake pad, the brake is effective, the brake pad is worn, the brake is squealed, etc. The brake performance can be stabilized.
[0009]
According to a second aspect of the present invention, when the brake amount distribution means increases the distribution of the hydraulic brake amount by the hydraulic brake when the estimated temperature of the brake pad is not more than a predetermined value, the estimated brake pad temperature When is more than a predetermined value, the amount of regenerative braking by regenerative braking is increased.
[0010]
According to the brake control device of the second aspect, when the estimated temperature of the brake pad is equal to or lower than a predetermined value, the distribution of the hydraulic brake amount by the hydraulic brake is increased and the temperature of the brake pad is increased. The effectiveness of the hydraulic brake can be improved, and when the estimated temperature of the brake pad is equal to or higher than the predetermined value, the distribution of the hydraulic brake amount is reduced by increasing the regenerative brake amount by the regenerative brake. The effect of the hydraulic brake can be improved by lowering the pad temperature.
[0011]
According to a third aspect of the present invention, there is provided the brake control device according to the first aspect, wherein the brake amount distribution means distributes the hydraulic brake amount by the hydraulic brake between the front wheel and the rear wheel based on the estimated temperature of the brake pad; And a second distribution means for distributing the hydraulic brake amount by the hydraulic brake between the left and right wheels based on the estimated temperature.
[0012]
According to a fourth aspect of the present invention, when the first distribution means has a brake pad temperature of a predetermined value or less, the ratio of the hydraulic brake amount to the front wheel is approximately 70%, and the hydraulic pressure to the rear wheel is set. The ratio of the brake amount is approximately 30%.
[0013]
According to a fifth aspect of the present invention, in the brake control device according to the fifth aspect, when the temperature of the brake pad is equal to or higher than a predetermined value, the ratio of the hydraulic brake amount to the front wheel is approximately 60%, and the hydraulic pressure to the rear wheel is set. The ratio of the brake amount is approximately 40%.
[0014]
According to the brake control device of the third to fifth aspects of the present invention, the hydraulic brake amount by the hydraulic brake is optimally distributed between the front wheel, the rear wheel, and the left and right wheels based on the estimated temperature of the brake pad. Brake performance can be ensured.
[0015]
The brake control device according to claim 6 is characterized in that the brake amount distribution means distributes the regenerative brake amount and the hydraulic brake amount based on different temperature-dependent characteristics between the front wheels and the rear wheels.
[0016]
Further, in the brake control device according to claim 7, the brake amount distribution means is in a cold state when the estimated temperature of the brake pad of the front wheel is lower than 20 ° C, and in a normal time in the case of 20 ° C to 500 ° C, When the temperature is higher than 500 ° C., the regenerative brake amount and the hydraulic brake amount are distributed at a high temperature.
[0017]
In the brake control device according to claim 8, the brake amount distribution means is in a cold state when the estimated temperature of the brake pad of the rear wheel is lower than 10 ° C, and in a normal time when it is between 10 ° C and 400 ° C. When the temperature is higher than 400 ° C., the regenerative brake amount and the hydraulic brake amount are distributed at a high temperature.
[0018]
According to the brake control device according to claims 6 to 8, in order to distribute the regenerative brake amount and the hydraulic brake amount based on different temperature-dependent characteristics between the front wheel and the rear wheel, the front wheel and the rear wheel Stable braking performance can be ensured.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a brake system and a drive system of an electric vehicle including a hydraulic brake (hydraulic brake) device and a regenerative brake device.
[0020]
As shown in FIG. 1, a traveling motor 10 is mounted on the front portion of the vehicle body 2. The traveling motor 10 is driven to rotate the left front wheel W _FL and the right front wheel W _FR as a driving wheel through a differential gear 12 and axle 14. The travel motor 10 is rotationally driven by a drive current supplied from a drive circuit 18 incorporating a converter that converts a direct current supplied from the battery 16 into an alternating current. The drive current value is controlled based on a control signal from an electronic control unit (ECU) 20 based on a detection value of an accelerator pedal depression amount detection sensor (not shown) that detects the depression amount of an accelerator pedal.
[0021]
Further, the traveling motor 10 forms a regenerative braking device in cooperation with the regenerative circuit 21 and also functions as a regenerative motor. The regenerative circuit 21 incorporates an inverter that converts an alternating current into a direct current. Based on a control signal from the ECU 20, the regenerative circuit 21 functions as a regenerative motor so that the power generated by the travel motor 10 is generated by the battery 16. To supply.
[0022]
A left front wheel brake B _FL and a right front wheel brake B _FR are mounted on the left front wheel W _FL and the right front wheel W _FR, and a left rear wheel brake B is mounted on the left rear wheel W _RL and the right rear wheel W _RR which are driven wheels. _RL and right rear wheel brake B _RR are mounted. Here, each wheel brake _BFL , _BFR , _BRL , _BRR is, for example, a disc brake.
[0023]
Brake fluid pressure corresponding to the depression operation of the brake pedal 23 is output from the first and second output ports 22A and 22B provided in the tandem master cylinder M. Note that the depression amount of the brake pedal 23 is detected by the brake pedal depression amount sensor 24 and input to the ECU 20.
[0024]
The output ports 22A and 22B are connected to the brake fluid pressure control device 25, and the brake fluid pressure from the brake fluid pressure control device 25 is transmitted to the wheel brakes _BFL , _BFR , _BRL and _BRR . In the brake fluid pressure control device 25, the wheel brakes _B FL based on the control signal from the ECU _20, B _FR, B _RL, the brake fluid pressure exerting on the _{B RR} is adjusted.
[0025]
The ECU 20 receives detection signals detected by wheel speed sensors 26 _FL , 26 _FR , 26 _RL , and 26 _RR that detect the wheel speeds of the wheels W _FL , W _FR , W _RL , and W _RR , respectively. . Further, ECU 20 is the wheel brakes _{B FL, B FR, B RL} , the temperature of the brake friction material in _{B RR,} i.e., the temperature of the wheel brakes _{B FL, B FR, B RL} , the brake pads of the disc brake of _{B RR} And a function of distributing the regenerative brake amount and the hydraulic brake amount (hydraulic brake amount), distributing the hydraulic brake amount between the front wheel brake and the rear wheel brake, and the like based on the estimated temperature.
[0026]
Next, brake control by the brake control device according to this embodiment will be described according to the flowchart shown in FIG.
[0027]
First, the ECU 20 reads a value detected by the pedal depression amount detection sensor 24 (step S10). That is, the amount of depression of the brake pedal 23 by the driver detected by the pedal depression amount detection sensor 24 is read. Based on the depression amount of the brake pedal 23, the target deceleration targeted by the driver is set (step S11).
[0028]
Next, the wheel brakes _{B FL, B FR, B RL} , estimates the temperature of the brake pad is a brake friction material constituting the _{B RR} (step S12). That is, first, the detection values by the wheel speed sensors 26 _FL , 26 _FR , 26 _RL , 26 _RR are read. Then, set the vehicle speed _{V W F} based average value of values detected by the wheel speed sensors ₂₆ FL, _{26 FR} to the front wheel speed to obtain the deceleration alpha _XF by differentiating the vehicle speed. Further, it defined as the vehicle speed V _{W R} based on rear wheel speed average value of values detected by the wheel speed sensor 26 _RL, 26 _RR, determine the deceleration alpha _XR by differentiating the vehicle speed.
[0029]
Then, the braking force or brake pressure _P F, _{P R} in the brake, based on proportional deceleration alpha _XF vehicles, the alpha _XR,
P _F = K1 × α _XF ( _Equation 1)
P _R = K1 × α _XR ( _Equation 2)
It is determined. Here, K1 is a proportionality coefficient.
[0030]
When the front wheel brake pad temperature is TF _n , the previous front wheel brake pad temperature is TF _n−1 , the heat generation coefficient is KU, and the heat dissipation coefficient is KD, the current front wheel brake pad temperature TF _n is ,
_{TF n = (TF n-1} + KU · P F · V W F) · KD ( number 3)
Estimate based on
[0031]
Also, the temperature of the rear wheel brake pad this time is TR _n , the temperature of the previous rear wheel brake pad TR _n−1 , the heat generation coefficient KU, and the heat dissipation coefficient KD. the _{TR n TR n = (TR n} -1 + KU · P R · V W R) · KD ( number 4)
Estimate based on In addition, when the distribution of the hydraulic brake amount is also performed for the left and right wheels, the temperature of the brake pad is estimated for each wheel.
[0032]
Next, based on the estimated temperature of the brake pad and the temperature dependence characteristic of the brake, the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake are distributed (step S13). The temperature-dependent characteristics of the front wheel brake and the rear wheel brake are determined in consideration of the temperature-dependent characteristics related to braking effectiveness, the temperature-dependent characteristics related to brake pad wear, and the temperature-dependent characteristics related to brake squeal. That is, FIG. 3 is a graph showing the temperature dependence characteristics regarding the effectiveness of the brake, and the optimum temperature A regarding the effectiveness of the brake is 10 ° C. <A <500 ° C. FIG. 4 is a graph showing temperature-dependent characteristics related to brake pad wear, and the optimum temperature A related to brake pad wear is A <500.degree. Further, FIG. 5 is a graph showing the temperature dependence characteristics related to brake squeal, and the optimum temperature A related to brake squeal is 20 ° C. <A <600 ° C. Therefore, taking into account the temperature-dependent characteristics related to the effectiveness of the brake, the temperature-dependent characteristics related to brake pad wear, and the temperature-dependent characteristics related to brake squeal, and further taking into account the characteristics of the front wheel brake and the rear wheel brake, Different temperature-dependent characteristics are set for the brake.
[0033]
Specifically, the distribution of the regenerative brake amount and the hydraulic brake amount performed in step S13 described above is performed as follows. That is, cold when the temperature TF _n of the brake pads of the front wheel brake which is estimated based on the wheel speed of the front wheel is lower than 20 ° C. is sometimes hydraulic braking amount by the regenerative braking amount and the hydraulic brake by the regenerative brake And make a distribution. In this case, 10% of the regenerative brake amount and 90% of the hydraulic brake amount are distributed (in the case of A <20 ° C. in FIG. 6).
[0034]
In the case of 20 ° C. to 500 ° C., as a normal time, the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake are distributed. In this case, 30% of the brake amount is distributed as the regenerative brake amount and 70% as the hydraulic brake amount (when 20 ° C. ≦ A ≦ 500 ° C. in FIG. 6). When the temperature is higher than 500 ° C., the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake are distributed at a high temperature. In this case, 40% of the regenerative brake amount and 60% of the hydraulic brake amount are allocated (in the case of 500 ° C. <A in FIG. 6).
[0035]
Further, when the temperature TR _n of brake pads rear wheel brake that is estimated based on the wheel speed of the rear wheels is lower than 10 ° C. is cold sometimes hydraulic by the regenerative braking amount and the hydraulic brake by the regenerative brake Distribute with brake amount. In this case, 10% of the brake amount is distributed as the regenerative brake amount and 90% as the hydraulic brake amount.
[0036]
In the case of 10 ° C. to 400 ° C., the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake are distributed as normal. In this case, 30% of the regenerative brake amount and 70% of the hydraulic brake amount are distributed. When the temperature is higher than 400 ° C., the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake are distributed at a high temperature. In this case, 40% of the brake amount is distributed as the regenerative brake amount and 60% as the hydraulic brake amount.
[0037]
Further, the hydraulic brake amount is distributed between 60% of the front wheels and 40% of the rear wheels when the temperatures of the brake pads of the front wheels and the rear wheel brakes are substantially equal. When the pad temperature is lower than 20 ° C. and the brake pad temperature of the rear wheel brake is 10 ° C. to 400 ° C., the hydraulic brake amount is distributed between 70% of the front wheels and 30% of the rear wheels. (When Af <20 ° C., 10 ° C. ≦ Ar ≦ 400 ° C. in FIG. 6).
[0038]
Next, based on the target deceleration set in step S11, the regenerative brake amount and hydraulic brake amount allocated in step S13, and the hydraulic brake amount allocated between the front wheels and the rear wheels, the regenerative brake and hydraulic pressure are determined. The brake is controlled (step S14). In other words, the brake fluid pressure control device 25 controls the brake amount in the wheel brakes B _FL , B _FR , B _RL , B _RR based on the control signal from the ECU 20, and the regenerative circuit based on the control signal from the ECU 20. 21 controls the amount of regenerative braking.
[0039]
According to the brake control device according to this embodiment, since the distribution of the regenerative brake amount and the hydraulic brake amount is optimally performed based on the temperature of the brake pad, the temperature of the brake pad is whatever the temperature. Thus, stable braking effectiveness can be ensured, wear of the brake pads can be reduced, and occurrence of brake squealing can be prevented.
[0040]
In addition, since the hydraulic brake amount by the hydraulic brake is optimally distributed between the front wheel, the rear wheel, and the left and right wheels based on the estimated temperature of the brake pad, stable braking performance can be ensured. Furthermore, since the regenerative brake amount and the hydraulic brake amount are distributed based on temperature-dependent characteristics that are different between the front wheels and the rear wheels, stable braking performance can be ensured for the front wheels and the rear wheels.
[0041]
【The invention's effect】
According to the present invention, since the distribution between the regenerative brake amount and the hydraulic brake amount is optimally performed based on the temperature of the brake pad, the brake performance such as braking effectiveness, brake pad wear, and brake squealing is stabilized. be able to.
[0042]
In addition, since the hydraulic brake amount by the hydraulic brake is optimally distributed between the front wheel, the rear wheel, and the left and right wheels based on the estimated temperature of the brake pad, stable braking performance can be ensured. Furthermore, since the regenerative brake amount and the hydraulic brake amount are distributed based on temperature-dependent characteristics that are different between the front wheels and the rear wheels, stable braking performance can be ensured for the front wheels and the rear wheels.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a brake system and a drive system of an electric vehicle including a hydraulic brake device and a regenerative brake device according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating brake control by the brake control device according to the embodiment of the present invention.
FIG. 3 is a graph showing temperature-dependent characteristics related to braking effectiveness according to the embodiment of the present invention.
FIG. 4 is a graph showing temperature-dependent characteristics related to wear of a brake pad according to an embodiment of the present invention.
FIG. 5 is a graph showing temperature-dependent characteristics relating to brake squeal according to the embodiment of the present invention.
FIG. 6 is a diagram for explaining the distribution of the brake amount according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 2 ... Car body, 10 ... Motor for driving | running | working, 12 ... Differential gear, 14 ... Axle, 16 ... Battery, 18 ... Drive circuit, 20 ... ECU, 21 ... Regenerative circuit, 22A ... 1st output port, 22B ... 2nd output Port, 23 ... Brake pedal, 24 ... Brake pedal depression amount sensor, 25 ... Brake fluid pressure control device, _26FL , _26FR , _26RL , _26RR ... Wheel speed sensor, _BFL , _BFR , _BRL , _BRR ... wheel brake, _WFL , _WFR , _WRL , _WRR ... wheels.

Claims (8)

In a brake control device for controlling a regenerative brake and a hydraulic brake by a traveling motor for vehicle traveling,
Target deceleration setting means for setting a target deceleration targeted by the driver based on the depression amount of the brake pedal;
Temperature estimating means for estimating the temperature of a brake pad constituting the hydraulic brake;
Brake amount distribution means for distributing the regenerative brake amount by the regenerative brake and the hydraulic brake amount by the hydraulic brake based on the estimated temperature of the brake pad estimated by the temperature estimation means;
A brake that controls the regenerative brake and the hydraulic brake based on the target deceleration set by the target deceleration setting means, the regenerative brake amount distributed by the brake amount distribution means, and the hydraulic brake amount. And a brake control device. The brake amount distribution means increases the distribution of the hydraulic brake amount by the hydraulic brake when the estimated temperature of the brake pad is not more than a predetermined value, and the estimated temperature of the brake pad is not less than a predetermined value. The brake control device according to claim 1, wherein a regenerative brake amount by the regenerative brake is increased. The brake amount distribution means includes
First distribution means for distributing the hydraulic brake amount by the hydraulic brake between the front wheel and the rear wheel based on the estimated temperature of the brake pad;
The brake according to claim 1, further comprising: a second distribution unit that distributes a hydraulic brake amount by the hydraulic brake between the left and right wheels based on the estimated temperature of the brake pad. Control device. When the temperature of the brake pad is equal to or lower than a predetermined value, the first distribution means sets the ratio of the hydraulic brake amount with respect to the front wheel to approximately 70%, and sets the ratio of the hydraulic brake amount with respect to the rear wheel to approximately 3 The brake control device according to claim 3, wherein the brake control device is a split. When the temperature of the brake pad is equal to or higher than a predetermined value, the first distribution means sets the hydraulic brake amount ratio to the front wheel to approximately 60% and the hydraulic brake amount ratio to the rear wheel to approximately 4 The brake control device according to claim 3, wherein the brake control device is a split. The brake amount distribution means distributes the regenerative brake amount and the hydraulic brake amount based on different temperature-dependent characteristics between the front wheels and the rear wheels. The brake control device according to any one of claims. When the estimated temperature of the brake pads for the front wheels is lower than 20 ° C., the brake amount distribution means is cold, normal when 20 ° C. to 500 ° C., and high when it is higher than 500 ° C. 7. The brake control device according to claim 6, wherein the regenerative brake amount and the hydraulic brake amount are distributed occasionally. When the estimated temperature of the brake pad for the rear wheel is lower than 10 ° C., the brake amount distribution means is in a cold state, when normal in the case of 10 ° C. to 400 ° C., and when higher than 400 ° C. The brake control device according to claim 6, wherein the regenerative brake amount and the hydraulic brake amount are distributed at a high temperature.

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