JP2010104087A - Regeneration control device of electric automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve brake performance by favorably balancing an electric regeneration torque component and a mechanical friction brake torque component in the control of brake torque, in a regeneration control device of an electric automobile. <P>SOLUTION: In the electric automobile having an electric motor which is regeneratively driven with respect to wheels, and a friction brake device which brakes the wheels, the regeneration control device controls a regeneration amount of the electric motor, and includes: a brake temperature calculation means 32 which calculates a brake temperature T<SB>e</SB>of the friction brake device; a brake frequency calculation means 33 which calculates the number of times of braking per prescribed travel distance as a brake frequency f; and a regeneration amount control means 31 which controls the regeneration amount N of the electric motor on the basis of the brake temperature T<SB>e</SB>calculated by the brake temperature calculation means 32 and the brake frequency f calculated by the brake frequency calculation means 33. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a regenerative control device for controlling a regenerative torque amount of an electric motor in an electric vehicle having an electric motor regeneratively driven by wheels and a friction braking device that brakes the wheels.

  In an electric vehicle that drives a wheel using a motor as a power source, control is performed to regenerate electric power by generating electric power with the motor using torque of a driving wheel during braking. The regenerative braking torque absorbed by the battery by the regenerative control works together with the friction braking torque consumed by a friction braking device such as a disc brake attached to the wheel as the braking torque of the vehicle. As described above, there has been proposed a technique for improving energy efficiency during braking by controlling the amount of regenerative braking torque when braking is performed by applying regenerative braking torque and friction braking torque to a wheel.

For example, Patent Document 1 discloses a technique for setting a high ratio of the regenerative braking torque to the entire braking torque in the initial stage of the braking operation. In this technique, when the brake switch is switched from the OFF state to the ON state, the magnitude of the regenerative braking torque is set to a magnitude corresponding to the driver's required braking torque, and the regenerative control is started. Thereafter, when the brake pedal is further depressed and a pressure equal to or higher than the first set operating force is applied to the pressurizing chamber of the master cylinder, the friction engagement member is brought close to the brake rotating body and the friction braking torque is applied. It is said that the energy recovery efficiency can be increased by such control.
JP 2003-284202 A

  Incidentally, the friction braking torque component of the brake torque composed of the electric regenerative torque component and the mechanical friction braking torque component changes according to the running state of the vehicle. For example, when the surface temperature rises due to contact friction between the friction engagement member and the brake rotating body, the friction coefficient changes, so even if the pressing force between the friction engaging element and the brake rotating body is the same. The friction braking torque component decreases.

Therefore, depending on the running state of the vehicle, the brake torque may be excessive or insufficient, and there is a problem that it is difficult to realize a good braking feeling. In particular, when a braking operation is repeatedly performed from a high speed, such a tendency becomes remarkable, and it becomes difficult to apply a braking force that meets the driver's request.
Further, in a friction braking device such as a disc brake, since braking is performed by physically contacting the friction engagement element and the brake rotating body, the amount of heat conduction from the brake rotating body to the friction braking device side is large. In this case, the amount of heat conduction is accumulated not only according to the surface temperature of the brake rotating body but also according to the pressing force of the frictional engagement elements and the braking frequency, so it is difficult to calculate accurately, resulting in a decrease in braking performance. There is also a problem that it is easy to invite.

  The present invention has been made in view of such a problem, and is capable of improving the braking performance while balancing the electrical regenerative torque component and the mechanical friction braking torque component in the control of the brake torque. An object of the present invention is to provide an electric vehicle regeneration control device.

  The regenerative control device for an electric vehicle according to the present invention (Claim 1) is a regenerative control device for controlling a regenerative torque amount of the motor in an electric vehicle having an electric motor driven to regenerate the wheel and a friction braking device for braking the wheel. The brake temperature calculating means for calculating the brake temperature of the friction braking device, the braking frequency calculating means for calculating the number of times of braking per predetermined travel distance as the braking frequency, and the brake calculated by the brake temperature calculating means Regenerative amount control means for controlling the regenerative torque amount of the electric motor based on the temperature and the braking frequency calculated by the braking frequency calculating means is provided.

Further, in the electric vehicle regeneration control device according to the present invention (claim 2), in addition to the configuration according to claim 1, the regeneration amount control means has the brake temperature equal to or higher than a preset predetermined temperature, and When the braking frequency is equal to or higher than a predetermined frequency set in advance, regenerative torque amount increase control for increasing the regenerative torque amount of the electric motor is performed.
An electric vehicle regeneration control device according to the present invention (Claim 3) includes, in addition to the configuration according to Claim 1 or 2, the brake temperature calculation means that calculates the amount of increase in the brake temperature. And a temperature drop amount calculating means for calculating the amount of decrease in the brake temperature.

The electric vehicle regeneration control device according to the present invention (Claim 4) further includes vehicle speed detection means for detecting the vehicle speed and vehicle weight calculation means for calculating the vehicle weight in addition to the configuration of Claim 3. The temperature increase amount calculating means calculates the amount of increase in the brake temperature based on the vehicle speed and the vehicle weight at the start of the braking operation and at the completion of the braking operation, respectively.
Further, in the electric vehicle regeneration control device according to the present invention (Claim 5), in addition to the configuration of Claim 4, the regeneration amount control means decreases the regeneration torque amount as the vehicle speed decreases during a braking operation. It is characterized by that.

  An electric vehicle regeneration control device according to the present invention (Claim 6) includes a cooling time constant for calculating a cooling time constant in the friction braking device in addition to the configuration according to any one of Claims 3 to 5. A calculating means; and a timing means for measuring an elapsed time from the completion of the braking operation, wherein the temperature decrease calculating means calculates the amount of decrease in the brake temperature based on the time constant and the elapsed time. It is characterized by.

According to the regeneration control device for an electric vehicle of the present invention (Claim 1), since the electric regeneration torque component is incremented in consideration of the brake temperature and the braking frequency, the friction braking torque component is reduced by the heat of the friction braking device, and A decrease in friction engagement performance due to heat conduction to the friction braking device can be suppressed, and good braking performance maintaining a desired brake torque as a whole can be ensured.
Further, according to the regenerative control device for an electric vehicle of the present invention (Claim 2), the friction brake device can be protected by the motor while suppressing the temperature rise of the brake temperature, and the thermal deterioration of the brake and the wear of the brake are prevented. Can be suppressed.

Further, according to the regeneration control device for an electric vehicle of the present invention (Claim 3), the element for raising the brake temperature and the element for lowering the temperature are separated and separately calculated, thereby accurately estimating the brake temperature. Is possible.
Moreover, according to the regeneration control device for an electric vehicle of the present invention (Claim 4), the amount of increase in brake temperature can be grasped with a simple configuration.

In addition, according to the regeneration control device for an electric vehicle of the present invention (Claim 5), the amount of regenerative torque is reduced immediately before the vehicle stops, so that the shock at the time of stop can be reduced and the brake feeling can be reduced. Can be improved.
Further, according to the regeneration control device for an electric vehicle of the present invention (Claim 6), the amount of decrease in the brake temperature can be grasped with a simple configuration.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIGS. 1-7 is for demonstrating the regeneration control apparatus of the electric vehicle which concerns on one Embodiment of this invention, FIG. 1 is a schematic diagram which shows the whole structure of the vehicle to which this regeneration control apparatus was applied, FIG. 2 is a block diagram showing the configuration of the regeneration control device, and FIGS. 3 and 4 are flowcharts for explaining the control procedure of the regeneration control device.

  FIG. 5 is a map used for estimating the vehicle weight in the regenerative control device, FIG. 6 is a map showing a cooling time constant set in the regenerative control device, and FIG. 7 is set in the regenerative control device. It is a graph which shows the regenerative characteristic.

[1. overall structure]
The regeneration control device of the present embodiment is applied to the electric vehicle 10. In this electric vehicle 10, wheels 11 are driven by a motor 14 (electric motor), and each wheel 11 is provided with a disk brake 15 (friction braking device). As shown in FIG. 1, in the electric vehicle 10 of the present embodiment, two rear wheels are mechanically connected to a motor 14 via a gear box 12.

  The electric vehicle 10 is also provided with an EV ECU 3 (Electric Vehicle Electronic Control Unit), an MCU 4 (Motor Control Unit), and an ASCU 5 (Active Stability Control Unit) as electronic control units related to braking control. Each of these control units 3, 4, and 5 is an electronic control device constituted by a microcomputer, and is provided as an LSI device in which a known microprocessor, ROM, RAM, and the like are integrated.

The EV ECU 3 is a higher-level control unit than the MCU 4 and the ASCU 5. That is, the EV ECU 3 has a function of managing the MCU 4 and the ASCU 5 in an integrated manner, and has jurisdiction over the timing and control amount setting and instruction of the control performed by the control units 4 and 5.
The MCU 4 receives specific instructions from the EV ECU 3, calculates specific control voltage and control current values, and transmits a control signal to the motor 14. The motor 14 functions as both a motor and a generator according to a control signal from the MCU 4.

The ASCU 5 controls the H / U 16 (Hydraulic Unit) in response to an instruction from the EV ECU 3 and individually controls the disc brake 15 of each wheel 11. The ASCU 5 has a so-called ASC function, and applies a braking force according to the grip force of each wheel 11 to each wheel 11 to improve posture stability.
For example, when a side slip of a wheel 11 is detected, a control is performed that generates a yaw moment that suppresses disturbance in posture by applying braking force to the wheel 11 and suppressing driving force of the other wheel 11 (ie, ASC control). To implement. As described above, the ASCU 5 has a function as a skid detection means for detecting a skid of the wheel 11. In addition, the presence or absence of the side slip of each wheel 11 judged by ASCU5 is input into EVECU3.

H / U 16 is an actuator that controls the brake fluid pressure introduced to the disc brake 15 of each wheel 11. This H / U 16 is connected to the brake master cylinder 8 by hydraulic piping, and receives the brake hydraulic pressure input via the brake booster 7 when the brake pedal 9 is depressed, and controls the disc brake 15 of each wheel 11. ing.
The brake pedal 9 is provided with a brake pedal SW6b (brake pedal switch), and whether or not the brake pedal 9 is depressed is input to the EV ECU 3. In this embodiment, either an on signal or an off signal is input to the EV ECU 3 in accordance with whether or not the brake pedal 9 is depressed.

Further, a brake fluid pressure sensor 6 a for detecting a braking pressure P in the master cylinder 8 generated by the depression of the brake pedal 9 is interposed on the hydraulic pipe connecting the brake master cylinder 8 and the H / U 16. The detection information here is also input to the EV ECU 3.
Further, the EVECU3, outside air temperature sensor 2 for detecting an acceleration sensor 1 and the air temperature T _a to detect the deceleration D acting on the vehicle body of the electric vehicle 10 (the longitudinal acceleration) is connected. The EV ECU 3 controls the MCU 4 based on the input information, and controls the regeneration amount of the motor 14 during braking.

  Each wheel 11 is provided with a speed sensor 13 for detecting the rotation speed. The rotation speed of each wheel 11 detected here is input to the ASCU 5. The ASCU 5 calculates the cumulative travel distance S and the vehicle speed V based on these rotational speeds, and the travel distance S and the vehicle speed V calculated here are input to the EV ECU 3. As described above, the ASCU 5 has a function as a vehicle speed detecting means and a function as a trip meter.

[2. EVECU]
A control configuration related to regenerative control during braking of the electric vehicle 10 will be described in detail.
As shown in FIG. 2, an acceleration sensor 1, an outside air temperature sensor 2, an ASCU 5, a brake fluid pressure sensor 6a, and a brake pedal SW 6b are connected to the input side of the EV ECU 3 as information sources for control. On the other hand, the MCU 4 is connected to the output side. The EVECU 3 is input with the deceleration D, the outside air temperature T _a , the presence / absence of depression of the brake pedal 9, the braking pressure P, the vehicle speed V, and the presence / absence of side slip of each wheel 11. estimating the brake temperature T _e of the brake 15 (surface temperature), and controls the regenerative torque amount N of the motor 14 via the MCU 4. The EV ECU 3 includes a regeneration amount control unit 31, a brake temperature calculation unit 32, and a braking frequency calculation unit 33.

[2-1. Brake temperature calculation means]
Brake temperature calculation section 32 is for estimating calculating the brake temperature T _e, calculates the temperature increase amount calculating unit 34 for calculating an increase amount T _b of the brake temperature T _e, the decrease amount T _c of the brake temperature T _e And a temperature drop amount calculation means 35 that is configured.
Heated amount calculating means 34, based on the vehicle weight W of the vehicle speed V _e and the electric vehicle 10 when the vehicle speed V _s and the braking operation completion at the start of braking operation, an increase in brake temperature T _e using Equation 1 below The amount _Tb is calculated.

ここでいう車両重量Ｗとは、いわゆる車体重量に乗員や積荷等の重量を加算した実総重量である。図５に示すように、ＥＶＥＣＵ３の内部には制動時の制動圧力Ｐ及び減速度Ｄと車体の慣性質量との対応関係を記述したマップが予め用意されており、このマップを用いて車両重量Ｗが求められるようになっている。図５中に示すように、車両重量Ｗが重いほど、同一の制動操作時に発生する減速度Ｄは小さくなる。なお、式１中のk₁は試験等により予め設定された係数である。このように、昇温量算出手段３４は、車両重量Ｗを算出する車両重量算出手段３４ａとしての機能を有している。

The vehicle weight W here is an actual total weight obtained by adding a weight of a passenger or a load to a so-called vehicle body weight. As shown in FIG. 5, a map describing the correspondence between the braking pressure P and deceleration D during braking and the inertial mass of the vehicle body is prepared in advance in the EV ECU 3, and the vehicle weight W is used using this map. Is now required. As shown in FIG. 5, the heavier the vehicle weight W, the smaller the deceleration D generated during the same braking operation. Incidentally, k ₁ in the formula 1 is a predetermined coefficient by the test and the like. As described above, the temperature increase amount calculating means 34 has a function as the vehicle weight calculating means 34a for calculating the vehicle weight W.

On the other hand, cooling amount calculation means 35, based on the elapsed time t after the completion of cooling time constant b and the braking operation of the brake disk 15, the decrease amount T _c of the brake temperature T _e using Equation 2 below calculate.

この式２中におけるブレーキ温度Ｔ_eとは、制動操作が完了した時点での温度である。また、図６に示すように、ＥＶＥＣＵ３の内部には冷却時定数ｂと車速Ｖとの対応関係を記述したマップが予め用意されており、このマップを用いて冷却時定数ｂが求められるようになっている。なお、式２中のk₂は試験等により予め設定された係数である。このように、降温量算出手段３５は、冷却の時定数ｂを算出する冷却時定数算出手段３５ａとしての機能と、制動操作完了時からの経過時間を計測する計時手段３５ｂとしての機能とを有している。

The brake temperature T _e during this formula 2, the temperature at the time of braking operation is complete. Further, as shown in FIG. 6, a map describing the correspondence between the cooling time constant b and the vehicle speed V is prepared in advance in the EV ECU 3, and the cooling time constant b is obtained using this map. It has become. Note that k _{2 in} Equation 2 is a coefficient preset by a test or the like. Thus, the temperature drop amount calculating means 35 has a function as the cooling time constant calculating means 35a for calculating the cooling time constant b and a function as the time measuring means 35b for measuring the elapsed time from the completion of the braking operation. is doing.

By the above calculation, when the first braking operation is complete, warm the brake temperature T _e is calculated by the braking operation, to be calculated as the brake temperature T _e is gradually lowered in accordance with the subsequent elapsed time It has become. Calculated here brake temperature T _e is input to the regeneration amount control means 31.

[2-2. Braking frequency calculation means]
The braking frequency calculating means 33 calculates the number of brakings per unit travel distance as a braking frequency f (braking frequency). Here, the brake frequency f [times / km] is calculated using Equation 3 below.

式３中におけるＣＢとは、ブレーキペダル９の踏み込み回数（例えば、電気自動車１０のメインキースイッチをオンにした時点からの累積回数）を示すカウンタ（ペダルスイッチカウンタ）であり、ここではブレーキペダルＳＷ６ｂからオン信号を受信した回数カウントすることによってこの踏み込み回数を把握している。また、Ｓ_s,Ｓ₀はそれぞれ、制動操作開始時の走行距離及び走行開始時の走行距離である。つまり、制動頻度算出手段３３は、制動操作開始時にＡＳＣＵ５から入力される累計走行距離ＳをＳ_sとして記憶するようになっている。このように、制動頻度算出手段３３では実際に走行した距離（Ｓ₀が記憶された地点からの走行距離）に対する制動回数が算出されている。

CB in Equation 3 is a counter (pedal switch counter) indicating the number of times the brake pedal 9 is depressed (for example, the cumulative number since the main key switch of the electric vehicle 10 is turned on), and here, the brake pedal SW6b By counting the number of times an ON signal has been received from this, the number of steps is determined. S _s and S ₀ are a travel distance at the start of the braking operation and a travel distance at the start of the travel, respectively. That is, the braking frequency calculating means 33 stores the cumulative travel distance S input from the ASCU 5 at the start of the braking operation as S _s . Thus, the braking frequency calculating means 33 calculates the number of times of braking with respect to the actually traveled distance (travel distance from the point where S ₀ is stored).

Incidentally, the cumulative travel distance S when the main key switch of the present electric vehicle 10 has been turned on is stored as S _0, with the configuration to reset the S ₀ when off the main key switch, trip each brake The frequency f is calculated.

[2-3. Regenerative amount control means]
Regeneration amount control means 31, in which the brake temperature T _e calculated by the brake temperature calculation section 32 to increase the regenerative torque amount N of the motor 14 as the temperature is high, to change the regeneration characteristics. First, as shown in FIG. 7, three types of regeneration characteristics are set in the regeneration amount control means 31 in advance.

The initial regenerative characteristic is a regenerative characteristic in which a regenerative torque amount N having a magnitude corresponding to an engine brake in a vehicle powered by an internal combustion engine is set. In the initial regenerative characteristics, as shown in FIG. 7, the magnitude of the regenerative torque N is N ₀ when the vehicle speed V during running (including braking) is equal to or higher than a predetermined speed V ₀ set in advance. Further, when the vehicle speed V becomes less than the predetermined speed V ₀ , the magnitude of the regenerative torque amount N gradually decreases, and the regenerative torque amount N is also set to 0 when the vehicle speed V = 0. The value of the predetermined speed V ₀ can be arbitrarily set, for example, 20 [km / h] or 30 [km / h].

In the first regeneration characteristic and the second regeneration characteristic, a regenerative torque amount N larger than the initial regeneration characteristic is set. When the vehicle speed V is equal to or higher than the predetermined speed V ₀ , the magnitude of the regenerative torque amount N is N ₂ and N ₁ (where N ₀ <N ₁ <N ₂ ), respectively. In any regenerative characteristic, the regenerative torque amount N decreases as the vehicle speed V decreases.
The regenerative amount control means 31 selects the first regenerative characteristic as the regenerative characteristic of the motor 14 when all of the following conditions [1] to [3] are satisfied. If both conditions [1] and [2] are satisfied and condition [3] is not satisfied, the second regeneration characteristic is selected as the regeneration characteristic of motor 14.
[1] the brake temperature T _e at the time of braking operation completion is skidding wheel 11 is not detected (ASC control is carried out) at a predetermined temperature T is ₀ [° C.] or [2] ASCU5 [3] brake frequency f As shown in FIG. 7, which is equal to or more than a predetermined frequency f ₀ [revolution / km] set in advance, the regeneration amount of the first regeneration characteristic is set to be larger than that of the second regeneration characteristic. The increment of the regenerative torque amount N at is set large. Therefore, as the brake temperature T _e is high, or higher brake frequency f is high, so that the increment of the regenerative torque amount N is set larger. In addition, as a specific example of the predetermined temperature T ₀ related to the condition [1], it can be considered to be about 300 [° C.].

On the other hand, when at least one of the conditions [1] and [2] is not satisfied, the initial regeneration characteristic is selected as the regeneration characteristic of the motor 14.
Further, when the brake pedal 9 is depressed, the regenerative amount control means 31 controls the regenerative torque amount N of the motor 14 based on the selected regenerative characteristic and the vehicle speed V. The setting contents of the regenerative torque amount N in the present embodiment are given by the following equations 4 to 9.

[3. flowchart]
A control procedure in the regeneration control device will be described with reference to FIGS. 3 and 4. These flows are repeatedly performed every time the main key switch of the electric vehicle 10 is turned on. Note that the step proceeding to A and B in FIG. 3 means proceeding to the steps A and B shown in FIG. 4, respectively, and the step proceeding to C in FIG. 4 is the step proceeding to C in FIG. It means to go to step C.

First, in step A10, an initial regeneration characteristic is set as an initial value of the regeneration characteristic of the motor 14. In step A20, with pedal switch counter CB is cleared in the braking frequency calculation unit 33, the travel distance S ₀ is stored. These flows are steps related to initialization of regenerative control according to the present invention. In the present embodiment, steps A10 and A20 are performed only once throughout the entire flow. However, for example, the configuration may be performed every time the main key switch is turned on, or at an arbitrary timing. It is good also as a structure which implements these flows again.

In the subsequent step A30, the outside air temperature T _a , the vehicle speed V, the braking pressure P, the deceleration D, the brake pedal SW signal, and the ASC control operation signal are input to the EV ECU 3 as information related to the regeneration control. Further, when the predicted brake temperature value _Te is calculated, the value is read.
In step A40, whether the brake temperature prediction value T _e is the outside air temperature T _a or not is determined. If T _e ≧ T _a (that is, if the surface of the disc brake 15 has heat), the process proceeds to step A50, where the brake temperature predicted value _Te is maintained as it is. On the other hand, if T _e <T _a (i.e., if the cold surface of the disk brake 15), the process proceeds to step A60, the outside air temperature T _a is set as a brake temperature prediction value T _e.

In the subsequent step A70, it is determined whether or not an ON signal is received from the brake pedal SW6b (that is, whether or not the brake pedal 9 is depressed). If the brake pedal 9 is depressed (braking operation is performed), the process proceeds to step A80. On the other hand, when it is not depressed (the braking operation is not performed), the process proceeds to B in FIG.
Steps A80 to 150 are mainly control contents during the braking operation. First, in step A80, the braking pressure P and deceleration D at that time are stored. These pieces of information are used for calculation of the vehicle weight W in the vehicle weight calculation means 34a. In step A90, the vehicle speed V at that time is stored as the vehicle speed V _s of the start braking operation. Vehicle speed V _s is one used to calculate the increase amount T _b of the brake temperature T _e at elevated amount calculation unit 34. Further, in step A100, the cumulative travel distance S at that time is stored as the travel distance S _s at the start of the braking operation. The travel distance S _s is used for calculating the brake frequency f in the braking frequency calculation means 33.

  In subsequent step A110, the regeneration amount of the motor 14 is set based on the regeneration characteristics and the vehicle speed V set at that time, and regeneration control is performed. In the present embodiment, after the braking operation is completed, the regenerative characteristic adopted at the next braking operation is set, so that the regenerative control based on the first regenerative characteristic and the second regenerative characteristic is performed. This is during the second and subsequent braking operations.

In step A120, it is determined whether the vehicle speed V is 0 or less. Here, it is determined whether the vehicle is stopped due to the braking operation. If V ≦ 0, the process proceeds to step A130, where V _e = 0 is stored as the vehicle speed V _e when the braking operation is completed, and the process proceeds to A in FIG. On the other hand, when V> 0 (that is, when the vehicle is not stopped), the routine proceeds to step A140.
In step A140, it is determined whether an off signal is received from the brake pedal SW6b. When the brake pedal 9 is depressed (braking operation is performed), the process proceeds to step A110, and the regeneration control is continued. On the other hand, that would braking operation is completed when the brake pedal 9 is not depressed, the flow advances to step A150, stores the vehicle speed V at that point in time as the vehicle speed V _e at the time of braking operation completion, in FIG. 4 Proceed to A.

The flow shown in FIG. 4 is the content of control in a state where the braking operation is not mainly performed. Step B10~B50 is a step of calculating an increase amount T _b of the brake temperature T _e by the braking operation, step B60~B120 is a step according to the setting of the regeneration characteristics, step B130~B160 the brake temperature T _e by heat radiation This is a step of calculating the amount of decrease _Tc .
In step B10, the timer t is reset to 0 in the time measuring means 35b, and measurement is started. The timer t indicates the elapsed time from the completion of the braking operation. In addition, the braking frequency calculation means 33 substitutes CB + 1 for the pedal switch counter CB and counts the number of times the brake pedal 9 is depressed.

In step B30, the vehicle weight W is estimated from the map shown in FIG. 5 in the vehicle weight calculation means 34a based on the braking pressure P and deceleration D during braking stored in step A80. In step B40, the increase amount T _b of the brake temperature T _e based on the equation 1 in elevated amount calculating means 34 is calculated. Then In step B50, the brake temperature T _e to T _e + T _b is substituted by the brake temperature T _e after heating is calculated. Brake temperature T _e, the more the vehicle weight W is large, as the vehicle speed V _s of the start braking operation is fast, or as the vehicle speed V _e at the time of braking operation completion is a low speed, a high temperature.

In step B60, the brake temperature T _e of the conditions [1] whether the predetermined temperature T ₀ or more is determined. Where, if a T _e ≧ T _0, the brake temperature T _e is considered to be a high temperature process advances to step B70, whereas, T _e <if it is T ₀ in the hot brake temperature T _e is so much The process proceeds to step B120, and the initial regeneration characteristic defined by Expression 4 and Expression 5 is set as the regeneration characteristic of the motor 14.

In Step B70, it is determined whether or not the skid of the wheel 11 according to the condition [2] is detected by the ASCU 5. If a side slip is detected, an initial regeneration characteristic is set in step B120 in order not to increase the braking force without darkness. On the other hand, if no skid is detected, the process proceeds to step B80 to increase the regeneration amount.
In step B80, the braking frequency calculation means 33 calculates the braking frequency f by Equation 3. Then In step B90, brake frequency f according to the conditions [3] in the regeneration amount control means 31 whether or not a predetermined frequency f ₀ or not is determined. Here, when the brake frequency f ≧ f ₀ , the process proceeds to step B100, where the regenerative characteristic is set to the first regenerative characteristic defined by Expression 8 and Expression 9. In this case, in this embodiment, the increment of the regenerative torque amount N is set to be the largest. On the other hand, if the brake frequency f <f ₀ , the process proceeds to step B110, where the regenerative characteristic is set to the second regenerative characteristic defined by Expression 6 and Expression 7.

If regenerative set in one of steps of the step B100~B120 is performed, followed by flow proceeds to step 130 after estimating calculating the decrease amount T _c of the brake temperature T _e. First, in step B130, the timer t started counting in step B10 is read, and in the subsequent step B140, the cooling time constant calculating means 35a determines the disc brake 15 from the map as shown in FIG. 6 according to the vehicle speed V at that time. A cooling time constant b is calculated.

Further, lowering the amount T _c of the brake temperature T _e based on the equation 2 is calculated in cooling amount calculating means 35 in step B150. Then, in the subsequent step B 160, brake temperature T _e after cooling is assigned a T _e -T _c to the brake temperature T _e is calculated. Then, it progresses to step A30 and repeat control is implemented.
Then, if the braking operation is performed, the setting of the regenerative properties proceeds from step A70 to step B60 and calculating the decrease amount T _c of the brake temperature T _e is repeated. For example, the brake temperature T _e is if reduced to less than the predetermined temperature T _0, the regenerative properties are healed is set to an initial regenerative properties. The actual regenerative control is not performed until the braking operation is performed, but the setting of the regenerative characteristic is changed at any time.

[4. Action, effect]
Thus, according to the present regeneration control device, the regeneration characteristic is changed so that the regeneration torque amount N increases when the brake temperature _Te reaches a predetermined temperature T ₀ or higher, so that the regeneration characteristic is applied to the disc brake 15. Regarding the brake torque, a decrease in the friction braking torque component due to heat can be covered by the increment of the electric regenerative torque component, and the brake torque as a whole can be ensured. Thereby, an increase in the braking distance can be suppressed.

Further, in the regeneration control device, the regenerative characteristic is set so that the amount of regeneration by the motor 14 as the brake frequency f is high is increased when the brake temperature T _e is the predetermined temperature T ₀ or more, in the disk brake 15 Heat conduction from the brake rotating body is suppressed, and deterioration and boiling due to the temperature rise of the brake fluid are less likely to occur. Accordingly, it is possible to prevent the braking force from being lowered and to ensure the braking performance of the disc brake 15.

According to the control of the regenerative control device, the disc brake 15 is protected by the motor 14, and wear of the disc brake 15 can be suppressed.
Further, the regenerative torque is reduced by reducing the regenerative torque amount T in a state where the skid is generated in the wheel 11, that is, in a situation where the vehicle body behavior is unstable such that the ASC control is performed, to return to the initial state. The vehicle body behavior can be stabilized while securing the amount T.

Further, in this regenerative control device, as defined in the above equations 4 to 9, the regenerative torque amount N in each regenerative characteristic is gradually reduced corresponding to the vehicle speed in the vehicle speed range just before the vehicle stops. Yes. Therefore, the shock at the time of a vehicle stop can be reduced and the brake feeling concerning regenerative control can be improved.
Further, in the regeneration control device, the a structure for grasping the brake temperature T _e, and a temperature increase amount detecting means 34 and a temperature lowering amount calculation means 35 calculates an estimated value of the brake temperature T _e, disc brake Compared with a configuration in which the surface temperature of 15 is directly measured, the configuration is simple and the cost can be reduced. Further, by separately calculating each separating the element for cooling the elements that raise the temperature of the brake temperature T _e, it is possible to apply the simple calculation model. Thus, the operation structure can be easily simplified, it is possible to accurately calculate the brake temperature T _e.

  Thus, according to the present invention, it is possible to achieve a good balance between the electric regenerative torque component and the mechanical friction braking torque component in the control of the brake torque.

[5. Others]
Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, although the conditions of the brake temperature T _e in the above embodiment [1] is not in the selection condition of the first regenerative properties or second regenerative properties, the regenerative torque of a magnitude corresponding to the brake temperature T _e The control may be changed so that N is obtained. In this case, if the regenerative characteristic is set so that the regenerative torque amount N increases as the brake temperature _Te is higher, it is possible to more accurately compensate for the decrease in the friction braking torque component due to heat.

In the embodiment described above, the regeneration characteristics of the three stages as shown in FIG. 7 are set in advance, by setting the regenerative properties of more levels, depending on the brake frequency f and the brake temperature T _e Thus, the regeneration characteristics can be set more finely, and the thermal deterioration of the disc brake 15 can be effectively prevented.
In the above-described embodiment, when the vehicle weight W is calculated by the vehicle weight calculation means 34a, the inertial mass of the vehicle body is estimated using the braking pressure P and the deceleration D during braking. It is also possible to use the stroke of the brake pedal 9 and the pedal depression force.

Further, in the above-described embodiment, the vehicle speed calculated by the MCU 4 is used as the vehicle speed V at the time of braking in the control by the EV ECU 3, but instead of this, a vehicle speed detected by a vehicle speed sensor (not shown) may be used. Alternatively, an integral value of the deceleration D may be used.
Further, instead of the acceleration sensor 1, a deceleration D is detected by using a stroke sensor for detecting the stroke of the brake pedal 9, a pressure sensor for detecting the hydraulic pressure of the brake master cylinder 8, a strain gauge for detecting the brake pedal force, and the like. It is good also as a structure which detects or calculates the parameter corresponded to. Alternatively, a differential value of the vehicle speed V may be used.

  Further, the conditions relating to the regeneration characteristics of the motor 14 are not limited to the above conditions [1] to [3]. Any of these conditions may be changed or omitted, or it may be possible to apply conditions for evaluating the stability of the vehicle such as the yaw rate or steering angle of the vehicle. That is, it is good also as a structure which suppresses the increase amount of regenerative torque in the state where not only the side slip of each wheel 11 but the yaw behavior and roll behavior of a vehicle body are unstable than the stable state. For example, the configuration may be such that the regenerative torque amount N is not increased during the operation of ABS or TCL (or the regenerative torque amount N increment is set slightly smaller).

In the above-described embodiment, the regenerative torque amount N in the motor 14 is increased when the conditions [1] and [2] are both satisfied, but the regenerative torque amount N is increased when either one is satisfied. It is also possible to increase the configuration. Further, for example, the brake temperature T _e configuration and to change the threshold of the brake frequency f (predetermined frequency f ₀₎ according to the condition (2) in response to the threshold (the predetermined temperature T according to the conditions according to the brake frequency f [1] ₀ ) may be changed.

In the above-described embodiment, the brake frequency f is calculated using the number of depressions CB of the brake pedal 9 and the travel distance (S _s −S ₀ ), but the brake frequency f is calculated in consideration of the braking pressure P. It is also possible to adopt a configuration to That is, it is considered that more accurate control can be expected by estimating the increase / decrease amount of the heat conduction amount due to the difference in the braking pressure P.
Note that specific set values such as the regenerative torque amounts N ₀ , N ₁ , N ₂ , the predetermined vehicle speed V ₀ , the predetermined temperature T _0, etc. in the above-described embodiment are arbitrary. Further, the control according to the present invention can be performed regardless of the shift position of the transmission. For example, the regenerative torque amount in the motor 14 can be increased regardless of whether the shift position is in the D range or the N range.

  In the above embodiment, the regenerative control device of the present invention is applied to the electric vehicle 10. However, the motor 14 (motor / generator) such as a hybrid electric vehicle (HEV) or a fuel cell vehicle (FCV) is used. Any vehicle that drives the wheels 11 and that includes a mechanical brake device can be suitably applied.

1 is a schematic diagram illustrating an overall configuration of a vehicle to which a regeneration control device for an electric vehicle according to an embodiment of the present invention is applied. It is a block diagram which shows the structure of this regeneration control apparatus. It is a flowchart for demonstrating the control procedure of this regeneration control apparatus. It is a flowchart for demonstrating the control procedure of this regeneration control apparatus. It is a map used for estimation of the vehicle weight in this regeneration control apparatus. It is a map which shows the time constant of the cooling set to this regeneration control apparatus. It is a graph which shows the regeneration characteristic set with this regeneration control apparatus.

Explanation of symbols

1 Acceleration sensor 2 Outside air temperature sensor 3 EVECU
4 MCU
5 ASCU (vehicle speed detection means)
6a Brake fluid pressure sensor 6b Brake pedal SW
7 Brake Booster 8 Brake Master Cylinder 9 Brake Pedal 10 Electric Car 11 Wheel 12 Gear Box 13 Speed Sensor 14 Motor (Electric Motor)
15 Disc brake (friction braking device)
16 H / U
31 Regenerative amount control means 32 Brake temperature calculation means 33 Braking frequency calculation means 34 Temperature increase amount calculation means 34a Vehicle weight calculation means 35 Temperature drop amount calculation means 35a Cooling time constant calculation means 35b Time measurement means

Claims (6)

In an electric vehicle having an electric motor regeneratively driven by a wheel and a friction braking device for braking the wheel, a regenerative control device for controlling a regenerative torque amount of the electric motor,
Brake temperature calculating means for calculating the brake temperature of the friction braking device;
Braking frequency calculating means for calculating the braking frequency per predetermined travel distance as a braking frequency;
Regenerative amount control means for controlling a regenerative torque amount of the electric motor based on the brake temperature calculated by the brake temperature calculating means and the braking frequency calculated by the braking frequency calculating means. Electric vehicle regenerative control device. The regenerative torque control means increases the regenerative torque amount of the electric motor when the brake temperature is equal to or higher than a predetermined temperature set in advance and the braking frequency is equal to or higher than a predetermined frequency set in advance. 2. The regeneration control device for an electric vehicle according to claim 1, wherein the increase control is performed. 3. The brake temperature calculating means includes: a temperature increase amount calculating means for calculating an increase amount of the brake temperature; and a temperature decrease amount calculating means for calculating a decrease amount of the brake temperature. The regenerative control device for the electric vehicle as described. Vehicle speed detection means for detecting the vehicle speed;
Vehicle weight calculation means for calculating vehicle weight,
The temperature increase amount calculating means calculates the amount of increase in the brake temperature based on the vehicle speed and the vehicle weight at the start of the braking operation and at the completion of the braking operation, respectively. Electric vehicle regeneration control device. 5. The regeneration control apparatus for an electric vehicle according to claim 4, wherein the regeneration amount control means decreases the regeneration torque amount as the vehicle speed decreases during a braking operation. A cooling time constant calculating means for calculating a cooling time constant in the friction braking device;
A timing means for measuring the elapsed time from the completion of the braking operation,
The regeneration of an electric vehicle according to any one of claims 3 to 5, wherein the temperature drop amount calculation means calculates a decrease amount of the brake temperature based on the time constant and the elapsed time. Control device.

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