JP2009292312A - Cooperative control device of composite brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer regenerative braking to frictional braking by surely terminating the regenerative braking in a low vehicle speed region, while preventing a regenerative braking termination control while vehicle speed is decreasing from becoming nonsmooth by fluctuation of driving wheel speed during shifting. <P>SOLUTION: A regenerative braking force limit value TmLmtde is determined based on driving wheel speed Vwde and a regenerative braking force limit value TmLmtdn is determined based on driven wheel speed Vwdn, during the shifts of t1 to t2 accompanying speed reduction. An absolute value lowering rate of the TmLmtdn is made larger than that of the TmLmtde in relation to lowering of vehicle speed. A smaller absolute value of the TmLmtde and TmLmtdn is contributed to a limit of regenerative braking force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a combined brake cooperative control device that generates a target braking force by two types of braking, ie, regenerative braking by a transmission motor / generator and friction braking by a hydraulic or electromagnetic brake device,
In particular, the present invention relates to a cooperative control device that smoothly makes a transition from regenerative braking to friction braking accompanying a decrease in vehicle speed.

  This type of composite brake can improve energy efficiency by utilizing regenerative braking to the maximum extent and pursuing cooperative control that supplements friction braking with a shortage of braking force with respect to the target braking force.

By the way, since the torque characteristic with respect to the rotational speed of the motor / generator changes so that the torque value increases as the rotational speed decreases, it is a flat characteristic that is maintained at substantially the same torque value in the low rotational range. The main cause is that the control accuracy of regenerative braking becomes worse in the low rotation range, and in this low rotation range, the rotational speed is originally low and the energy recovery efficiency due to regenerative braking may decrease.
In this low rotation range, and thus in a low vehicle speed range, the target braking force is usually realized only by friction braking without using regenerative braking.

  However, after entering the low rotation range (low vehicle speed range) determined based on the above grounds, if the regenerative braking force is set to zero and added to the friction braking force, switching from regenerative braking to friction braking is necessary. Smooth timing control is difficult, and the occurrence of shock due to the switching is unavoidable.

Therefore, conventionally, as a cooperative control technique at the time of switching from regenerative braking to friction braking accompanying a decrease in vehicle speed, for example, a cooperative control technique as disclosed in Patent Document 1 has been disclosed.
This coordinated control technology gradually reduces the regenerative braking force as the vehicle speed decreases, and gradually increases the friction braking force by that amount, just before entering the low rotation range (low vehicle speed range). Thus, a transition from regenerative braking to friction braking is performed.

According to such cooperative control technology, since the transition from regenerative braking to friction braking is completed when entering the low rotation range (low vehicle speed range), theoretically, from regenerative braking accompanying reduction in vehicle speed to friction braking. Switching to can be performed smoothly.
JP 2004-196064 A

However, in an electric vehicle such as a hybrid vehicle or an electric vehicle in which at least a motor / generator is mounted as a prime mover, and the motor / generator and a front wheel or a rear wheel, which are driving wheels, can be driven and connected by a transmission. In that case
When the above-mentioned transmission shifts during regenerative braking and the wheel driving force changes temporarily, the change in the driving wheel speed due to this driving force change is caused by the regenerative braking force limit amount (regenerative braking force limit value) and friction. A change in braking force is caused, causing a problem that the transition from regenerative braking to friction braking cannot be smoothly performed when the vehicle speed is reduced.

However, as described in Patent Document 1, in the case of the above control, when the wheel speed of the driven wheel (driven wheel speed) is used as the vehicle speed instead of the driving wheel speed,
When the driving wheel speed decreases due to braking slip of the driving wheel (when entering the low vehicle speed range), there arises a problem that the transition to friction braking cannot be completed.

The present invention relates to a decrease in vehicle speed based only on one of a driving wheel speed reference regenerative braking force limit value obtained using the driving wheel speed as the vehicle speed and a driven wheel speed reference regenerative braking force limit value obtained using the driven wheel speed as the vehicle speed. As long as the regenerative braking force is limited, it is impossible to prohibit one of the above problems from occurring.
The drive wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value are given a predetermined difference between the drive wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value. It is an object of the present invention to provide a combined brake cooperative control apparatus that does not cause any of the above problems by properly using the above-mentioned.

For this purpose, the coordinated control device for a composite brake according to the present invention is as described in claim 1,
An electric vehicle equipped with at least a motor / generator as a prime mover and capable of drivingly coupled between the motor / generator and a front wheel or a rear wheel which is a driving wheel by a transmission,
The target braking force determined according to the driving state and traveling state of the vehicle is realized by cooperation of the regenerative braking by the motor / generator and the friction braking by the brake device, but the regenerative braking force is limited and reduced as the vehicle speed decreases. In the composite brake of a vehicle that is shifted to friction braking by
A driving wheel speed reference regenerative braking force limit value for the restriction is obtained using the driving wheel speed of the front wheel or rear wheel as the driving wheel as the vehicle speed, and the driven wheel speed of the rear wheel or front wheel as the driven wheel is determined as the vehicle speed. As follows, the driven wheel speed reference regenerative braking force limit value for the limitation is obtained,
The driving wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value relative to the decrease rate of the vehicle wheel speed are relatively lower than the driving wheel speed reference regenerative braking force limit value decreasing rate. Regenerative braking force limit value calculating means for giving a difference such that the rate of decrease of the regenerative braking force limit value increases;
Of the driving wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value obtained by the means, the smaller regenerative braking force limit value is used as the regenerative braking force limit value that contributes to the limitation of the regenerative braking force. And selecting means.

According to the configuration of the present invention,
The absolute value of the driving wheel speed reference regenerative braking force limit value is the driven wheel speed reference regenerative braking force limit value for the degree of change in the driving wheel speed reference regenerative braking force limit value that accompanies changes in the driving wheel speed due to gear shifting. The absolute value of the value is never smaller, and the regenerative braking force is limited based on the driven wheel speed reference regenerative braking force limit value.
It is possible to avoid the former problem that the change in the drive wheel speed reference regenerative braking force limit value due to the change in the drive wheel speed caused by the shift or the like prevents the smooth transition from the regenerative braking to the friction braking due to the decrease in the vehicle speed. it can.

On the other hand, when the driving wheel speed drops due to braking slip of the driving wheel and the low vehicle speed range where the transition to friction braking should be completed after regenerative braking is completed, the driving wheel speed reference regenerative braking force is limited. The absolute value of the value is smaller than the absolute value of the driven wheel speed reference regenerative braking force limit value, and the regenerative braking force is limited based on the drive wheel speed reference regenerative braking force limit value.
Therefore, when the driving wheel speed is reduced due to braking slip of the driving wheel and the vehicle is in the low vehicle speed range, the regenerative braking can be surely finished and the transition to the friction braking can be completed. Despite this, the latter problem that the transition from regenerative braking to friction braking cannot be completed can also be solved.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a front engine / rear wheel drive type hybrid vehicle (electric vehicle) equipped with a composite brake cooperative control device according to an embodiment of the present invention, together with its control system. , 2FR are left and right front wheels (left and right driven wheels), and 3RL and 3RR are left and right rear wheels (right and left drive wheels), respectively.
In the power train of the hybrid vehicle shown in FIG. 1, an automatic transmission 4 is arranged in tandem at the rear of the engine 1 in the vehicle front-rear direction in the same manner as a normal rear wheel drive vehicle, and the engine 1 (specifically, the crankshaft 1a) A motor / generator 6 (prime mover) is provided coupled to the shaft 5 that transmits the rotation to the input shaft 4a of the automatic transmission 4.

The motor / generator 6 includes an annular stator 6a fixed in the housing and a rotor 6b disposed concentrically with a predetermined air gap in the stator 6a. Acts as an electric motor) or as a generator (generator), and is disposed between the engine 1 and the automatic transmission 4.
The motor / generator 6 is connected to the center of the rotor 6b through the shaft 5, and this shaft 5 is used as a motor / generator shaft.

The first clutch 7 is inserted between the motor / generator 6 and the engine 1, more specifically, between the motor / generator shaft 5 and the engine crankshaft 1a, and the engine 1 and the motor / generator 6 are connected by the first clutch 7. Combine in a detachable manner.
Here, it is assumed that the first clutch 7 is capable of continuously changing the transmission torque (clutch engagement) capacity. For example, the first clutch 7 continuously controls the clutch hydraulic oil flow rate and the clutch operation hydraulic pressure with a proportional solenoid to transmit the transmission torque (clutch engagement). ) Consists of wet multi-plate clutch with variable capacity.

The motor / generator 6 and the automatic transmission 4 are directly coupled to each other by direct coupling of the motor / generator shaft 5 and the transmission input shaft 4a.
The automatic transmission 4 is similar to the known planetary gear set type automatic transmission, except that the torque converter is excluded from this, and instead the motor / generator 6 is directly coupled to the transmission input shaft 4a. ,
By selectively engaging or releasing a plurality of speed change friction elements (clutch, brake, etc.), the transmission system path (speed stage) is determined by a combination of engagement and release of these speed change friction elements.

Accordingly, the automatic transmission 4 shifts the rotation from the input shaft 4a with a gear ratio corresponding to the selected shift speed, and outputs it to the output shaft 4b.
This output rotation is distributed and transmitted to the left and right rear wheels 3RL and 3RR by the differential gear device 8, and is used for traveling of the vehicle.
However, it goes without saying that the automatic transmission 4 is not limited to the stepped type as described above, and may be a continuously variable transmission.

In the hybrid vehicle, the second clutch 9 that detachably couples the motor / generator 6 and the drive wheels 3RL and 3RR is necessary.
In this embodiment, the second clutch 9 is not added to the automatic transmission 4 or after the automatic transmission 4, and a new configuration is not adopted.
Instead, among the above-described shift friction elements existing in the automatic transmission 4, as the second clutch 9, a shift friction element for selecting a forward shift stage or a shift friction element for selecting a reverse shift stage is used.

Incidentally, in the automatic transmission 4 used as the second clutch 9, the existing transmission friction element for selecting the forward shift stage or the shift friction element for selecting the reverse shift stage is originally transmitted torque capacity similarly to the first clutch 7 described above. The (clutch engagement capacity) can be continuously changed.
Thus, the existing shift friction element for selecting the forward shift stage (starting friction element) or the shift friction element for selecting the reverse shift stage (starting friction element) is diverted to the automatic transmission 4 as the second clutch 9. In that case, in addition to the second clutch 9 fulfilling the mode selection function described below, the automatic transmission is put into a power transmission state by shifting to the corresponding gear stage when engaged to fulfill this function, There is no need for a dedicated second clutch, which is very advantageous in terms of cost.

The power train mode selection function described above with reference to FIG. 1 will be described below.
In the power train shown in FIG. 1, when the electric driving (EV driving) mode used at low load and low vehicle speed including when starting from a stopped state is required, the first clutch 7 is disengaged and the automatic shifting is performed. The machine 4 is brought into a power transmission enabled state by engaging the second clutch 9.

When the motor / generator 6 is driven in this state, only the output rotation from the motor / generator 6 reaches the transmission input shaft 4a, and the automatic transmission 4 changes the rotation to the input shaft 4a to the selected shift speed. The speed is changed according to the speed and output from the transmission output shaft 4b.
The rotation from the transmission output shaft 4b then reaches the rear wheels 3RL and 3RR via the differential gear device 8, and the vehicle can be electrically driven (EV traveling) only by the motor / generator 6.

When the hybrid travel (HEV travel) mode used for high speed travel or heavy load travel is required, the first clutch 7 is engaged and the automatic transmission 4 can be transmitted power by engaging the second clutch 9. To.
In this state, the output rotation from the engine 1, or both the output rotation from the engine 1 and the output rotation from the motor / generator 6 reach the transmission input shaft 4a, and the automatic transmission 4 is connected to the input shaft 4a. Is rotated according to the selected gear position and output from the transmission output shaft 4b.
The rotation from the transmission output shaft 4b then reaches the rear wheels 3RL and 3RR via the differential gear device 8, and the vehicle can be hybrid-run (HEV-run) by both the engine 1 and the motor / generator 6.

  In such HEV traveling, if the engine 1 is operated with the optimum fuel efficiency and the energy becomes surplus, the surplus energy is converted into electric power by operating the motor / generator 6 as a generator by this surplus energy, and this generated power is converted into electric power. By accumulating power to be used for driving the motor of the motor / generator 6, the fuel consumption of the engine 1 can be improved.

Hereinafter, a control system for the engine 1, the motor / generator 6, the first clutch 7, and the second clutch 9 constituting the power train of the hybrid vehicle described above will be schematically described with reference to FIG.
This control system includes an integrated controller 11 that performs integrated control of the operating point of the power train. The operating point of the power train includes the target engine torque tTe, the target motor / generator torque tTm, and the target engagement capacity of the first clutch 7. It is defined by tTc1 (first clutch engagement pressure command value tPc1) and target engagement capacity tTc2 (second clutch engagement pressure command value tPc2) of the second clutch 9.

In the integrated controller 11, in order to determine the operating point of the power train,
A signal from the engine speed sensor 12 for detecting the engine speed Ne;
A signal from the motor / generator rotation sensor 13 for detecting the motor / generator rotation speed Nm,
A signal from the input rotation sensor 14 for detecting the transmission input rotation speed Ni;
A signal from the output rotation sensor 15 that detects the transmission output rotation speed No,
A signal from the accelerator opening sensor 16 for detecting the accelerator pedal depression amount (accelerator opening APO);
A signal from a storage state sensor 17 that detects a storage state SOC (carryable power) of a battery 31 that stores power for the motor / generator 6;
A signal from the master cylinder hydraulic pressure sensor 18 that detects the master cylinder hydraulic pressure Pm according to the brake pedal depression force,
Signals from a wheel speed sensor group 21 that individually detect the wheel speeds Vw of the left and right front wheels (left and right driven wheels) 2FL and 2FR and the left and right rear wheels (right and left drive wheels) 3RL and 3RR are input.

  The integrated controller 11 is a driving mode in which the driving force of the vehicle desired by the driver can be realized from the accelerator opening APO, the battery storage state SOC, and the transmission output rotational speed No (vehicle speed VSP) among the above input information. (EV mode, HEV mode) is selected, and target engine torque tTe, target motor / generator torque tTm, first clutch target engagement capacity tTc1, and second clutch target engagement capacity tTc2 are calculated.

  The target engine torque tTe is supplied to the engine controller 32. The engine controller 32 realizes the target engine torque tTe based on the engine speed Ne from the engine speed Ne detected by the sensor 12 and the target engine torque tTe. Therefore, the engine 1 is controlled so that the engine torque becomes the target engine torque tTe by the throttle opening control and the fuel injection amount control.

  The target motor / generator torque tTm is supplied to the motor / generator controller 33. The motor / generator controller 33 converts the electric power of the battery 31 from DC to AC by the inverter 34, and the motor / generator 6 under the control of the inverter 34. And the motor / generator torque is controlled so that the motor / generator torque matches the target motor / generator torque tTm.

When the target motor / generator torque tTm is such that the motor / generator 6 requires regenerative braking action, the motor / generator controller 33 is connected to the battery storage state SOC detected by the sensor 17 via the inverter 34 (can be taken out) In relation to the electric power), a power generation load is applied to the motor / generator 6 so that the battery 31 is not overcharged.
The electric power generated by the regenerative braking by the motor / generator 6 is AC-DC converted and the battery 31 is charged.

When the braking force is insufficient with only the regenerative braking of the motor / generator 6, the integrated controller 11 uses the brake braking command value Tf as a regenerative cooperative brake control command to supplement the insufficient braking force with the hydraulic brake system. Supply to 35.
When there is no regenerative cooperative brake control command (when the friction braking force command value Tf = 0), the brake controller 35 receives a signal from the master cylinder hydraulic pressure sensor 18 that detects the master cylinder hydraulic pressure Pm according to the brake pedal depression force. Originally, the brake fluid pressure of each wheel brake unit is controlled to a fluid pressure corresponding to the master cylinder fluid pressure Pm under appropriate front and rear wheel braking force distribution control,
When receiving the regenerative cooperative brake control command (friction braking force command value Tf> 0) from the integrated controller 11, the brake controller 35 is configured to apply the friction braking force command value Tf (> 0) to each wheel brake unit by the hydraulic brake system. The brake fluid pressure is controlled to a fluid pressure corresponding to the friction braking force command value Tf under appropriate front and rear wheel braking force distribution control.

  The first clutch target engagement capacity tTc1 is supplied to the first clutch controller 36. The first clutch controller 36 detects the first clutch engagement pressure command value tPc1 corresponding to the first clutch target engagement capacity tTc1 and the sensor 19. The first clutch 7 is engaged via the first clutch engagement pressure control unit 37 so that the engagement pressure Pc1 of the first clutch 7 becomes the first clutch engagement pressure command value tPc1 by comparison with the engagement pressure Pc1 of the first clutch 7. The engagement capacity of the first clutch 7 is controlled by controlling the pressure.

The second clutch target engagement capacity tTc2 is supplied to the transmission controller 38,
The transmission controller 38 compares the second clutch engagement pressure command value tPc2 corresponding to the second clutch target engagement capacity tTc2 with the engagement pressure Pc2 of the second clutch 9 detected by the sensor 20, and The engagement capacity of the second clutch 9 is controlled by controlling the engagement pressure of the second clutch 9 via the second clutch engagement pressure control unit 39 so that the engagement pressure Pc2 becomes the second clutch engagement pressure command value tPc2.

The transmission controller 38 selects a gear suitable for the current driving state based on the planned shift map from the transmission output rotation speed No (vehicle speed VSP) detected by the sensor 15 and the accelerator opening APO detected by the sensor 16. And the automatic shift from the current shift stage to this preferred shift stage is also performed.
During the automatic shift from the current shift speed to the preferred shift speed, a shift signal indicating that the shift is being performed is supplied to the integrated controller 11.

The above is an outline of the normal control executed by the control system of FIG.
In this embodiment, the integrated controller 11 in FIG. 1 executes the control program shown in FIGS. 2 and 3 during braking by depressing a brake pedal (not shown), and performs cooperative control of the composite brake as follows. And
FIG. 2 shows a main routine related to the cooperative control of the composite brake, and FIG. 3 shows a calculation process of the regenerative braking force limit value at the time of vehicle speed reduction obtained in the main routine.

In the main routine of FIG. 2, first, in step S11, the target braking force Tb of the vehicle requested by the driver by depressing the brake pedal (hereinafter, the braking force is described as a negative value) is calculated.
In calculating the target braking force Tb, the master cylinder hydraulic pressure Pm detected by the sensor 18 (may be a brake pedal depression stroke) may be obtained by searching based on a planned target braking force map. You may obtain | require by the calculation using a vehicle model.

  In the next step S12, the regenerative braking force limit value TmLmt at the time of vehicle speed reduction for gradually restricting regenerative braking and smoothly shifting to friction braking before the vehicle speed VSP decreases to the above-described regenerative braking prohibited low vehicle speed range is set. Calculated as described later with reference to FIG.

  In step S13, whether or not Tb <TmLmt (| Tb |> | TmLmt |) is obtained by comparing the target braking force Tb obtained in step S11 with the vehicle speed decrease regenerative braking force limit value TmLmt obtained in step S12. No (If the regenerative braking force is limited to the regenerative braking force limit value TmLmt when the vehicle speed is reduced, the regenerative braking force alone will be insufficient for the target braking force Tb and it will be necessary to rely on friction braking for the shortage ) Is checked.

When it is determined in step S13 that Tb ≧ TmLmt (| Tb | ≦ | TmLmt |), that is, even if the regenerative braking force is limited to the regenerative braking force limit value TmLmt when the vehicle speed is reduced, the target control is performed only by regenerative braking. When you can cover the power Tb and friction braking is unnecessary,
Control is advanced to step S14, the regenerative braking force command value Tm is set to the same value as the target braking force Tb, and the regenerative braking force command value Tm thus determined is set to the target motor / generator torque tTm.
Next, in step S15, the friction braking force command value Tf is set to zero.

However, when it is determined in step S13 that Tb <TmLmt (| Tb |> | TmLmt |), that is, if the regenerative braking force is limited to the regenerative braking force limit value TmLmt when the vehicle speed is reduced, the target is not obtained with only the regenerative braking force. When it is not possible to cover the braking force Tb and the braking force is insufficient, and it is necessary to rely on friction braking for the shortage,
The control proceeds to step S16, the regenerative braking force command value Tm is set to the same value as the regenerative braking force limit value TmLmt when the vehicle speed decreases, and the regenerative braking force command value Tm thus determined is set to the target motor / generator torque tTm. .
In the next step S17, the regenerative braking force command value Tm (= TmLmt) determined as described above and the target braking force Tb obtained in step S11, the regenerative braking alone is applied to the target braking force Tb. The insufficient braking force deficiency (Tb−TmLmt) is obtained, and this insufficient braking force deficiency (Tb−TmLmt) is set to the friction braking force command value Tf.

  The integrated controller 11 shows the target motor / generator torque tTm (regenerative braking force command value Tm) and the friction braking force command value Tf obtained in steps S14 and S15 or steps S16 and S17, respectively, as shown in FIG. To the motor / generator controller 33 and the brake controller 35.

The motor / generator controller 33 applies a power generation load corresponding to the target motor / generator torque tTm (regenerative braking force command value Tm) to the motor / generator 6 via the inverter 34 and performs regenerative braking corresponding to the regenerative braking force command value Tm. Do.
The electric power generated by the regenerative braking by the motor / generator 6 is AC-DC converted via the inverter 34 and charged in the battery 31 to be used for the motor operation after the motor / generator 6.

  In response to the friction braking force command value Tf> 0 (regenerative coordination brake control command), the brake controller 35 adjusts the brake hydraulic pressure of each wheel brake unit in order to realize the friction braking force command value Tf by the hydraulic brake system. The fluid pressure is controlled according to the friction braking force command value Tf under appropriate front and rear wheel braking force distribution control.

By the way, in the present embodiment, the above-mentioned object of the present invention is achieved by assuming that the calculation point of the regenerative braking force limit value TmLmt at the time of vehicle speed reduction obtained in step S12 of FIG. 2 is as shown in FIG.
As described above, the regenerative braking force limit value TmLmt when the vehicle speed is reduced is a regenerative system for gradually restricting regenerative braking and smoothly shifting to friction braking before the vehicle speed VSP decreases to the above-described regenerative braking prohibited low vehicle speed range. Power limit value.

  In calculating the regenerative braking force limit value TmLmt when the vehicle speed is reduced, the integrated controller 11 first, in step S21, the battery storage state SOC (power that can be taken out) detected by the sensor 17, the motor / generator rotation speed Nm detected by the sensor 13, etc. The maximum allowable regenerative force Tmmax (negative value) determined from is read by map search.

In the next step S22, the average driving wheel speed Vwde of both wheels is calculated from the wheel speeds of the left and right driving wheels (left and right rear wheels) 3Rl and 3RR among the wheel speeds detected by the wheel speed sensor group 21,
In step S23, the driven wheel speed average value Vwde is calculated from the wheel speeds of the left and right driven wheels (left and right front wheels) 2Rl and 2RR among the wheel speeds detected by the wheel speed sensor group 21.
In step S24 corresponding to the regenerative braking force limit value calculating means, a driving wheel speed reference regenerative braking force limit value TmLmtde (negative value) is calculated by calculating the driving wheel speed average value Vwde as the vehicle speed VSP. The driven wheel speed reference regenerative braking force limit value TmLmtdn (negative value) is calculated by calculating the moving wheel speed average value Vwdn as the vehicle speed VSP.

  Since the driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn are limit values for largely limiting regenerative braking as the vehicle speed decreases as described above, they are illustrated in FIG. It is assumed that the absolute value gradually decreases as the vehicle speed VSP (the driving wheel speed average value Vwde, the driven wheel speed average value Vwdn) decreases, and finally becomes zero.

However, in calculating the driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn, as shown in comparison with the solid line and broken line in FIG. Vwde, driven wheel speed reference regenerative braking force limit value TmLmtde and driven wheel speed reference regenerative braking force limit value TmLmtdn relative to the decrease rate of absolute value of drive wheel speed reference regeneration relative to the decrease in driven wheel speed average value Vwdn) A difference is set such that the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn is larger than the absolute value decrease rate of the braking force limit value TmLmtde.
This difference is also caused by the change in the drive wheel speed reference regenerative braking force limit value TmLmtde due to the change in the drive wheel speed average value Vwde caused by the shift of the automatic transmission 4. The difference is such that the absolute value does not fall below the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn.

In setting the difference between the absolute value decrease rate of the driving wheel speed reference regenerative braking force limit value TmLmtde and the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn as described above,
By adjusting to decrease the absolute value decrease rate of the drive wheel speed reference regenerative braking force limit value TmLmtde, the absolute value decrease rate of the drive wheel speed reference regenerative braking force limit value TmLmtde to the vehicle speed decrease is changed to the driven wheel speed reference regenerative control to the vehicle speed decrease. It may be smaller than the absolute value decrease rate of the power limit value TmLmtdn,
By adjusting to increase the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn, the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn to the vehicle speed decrease becomes the driving wheel speed reference regenerative system to the vehicle speed decrease. It may be larger than the absolute value decrease rate of the power limit value TmLmtde,
By combining the adjustment to decrease the absolute value decrease rate of the driving wheel speed reference regenerative braking force limit value TmLmtde and the adjustment to increase the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn, these absolute value decrease rates The above difference may be set between them.

In step S25 of FIG. 3, it is checked whether or not the automatic transmission 4 is shifting depending on whether or not there is a shifting signal from the transmission controller 38 shown in FIG.
Since the above-described problem to be solved by the present invention does not occur unless the speed is changed, the regenerative braking force limit when the vehicle speed is reduced based on the driving wheel speed is lower when the vehicle speed is reduced based on the driven wheel speed as described above. Because it is preferable to the regenerative braking force limit,
In step S26, the driving wheel speed reference regenerative braking force limit value TmLmtde is set to the regenerative braking force limit value TmLmt when the vehicle speed decreases.
Thereafter, in step S32, the vehicle speed decrease regenerative braking force limit value TmLmt is stored as a vehicle speed decrease regenerative braking force limit value TmLmt (previous value) so as to contribute to the control described later.

When it is determined in step S25 that shifting is in progress, whether or not the drive wheel speed reference regenerative braking force limit value TmLmtde is greater than the driven wheel speed reference regenerative braking force limit value TmLmtdn (| TmLmtde | <| TmLmtdn |) in step S27. To check.
When it is determined in step S27 that TmLmtde> TMLmtdn (| TmLmtde | <| TmLmtdn |), that is, the driven wheel speed reference regenerative braking force limit value TmLmtdn is larger than the driving wheel speed reference regenerative braking force limit value TmLmtde (| TmLmtde | > | TmLmtdn |)
In step S28, the driven wheel speed standard regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn have a smaller absolute value, that is, a driven wheel speed standard regenerative system that greatly restricts regenerative braking. The power limit value TmLmtdn is set to the regenerative braking force limit value TmLmt when the vehicle speed decreases.
Therefore, step S28, together with step S27, constitutes the regenerative braking force limit value selection means in the present invention.
Thereafter, in step S32, the vehicle speed decrease regenerative braking force limit value TmLmt is stored as a vehicle speed decrease regenerative braking force limit value TmLmt (previous value) so as to contribute to the control described later.

When it is determined in step S27 that the driving wheel speed reference regenerative braking force limit value TmLmtde is larger than the driven wheel speed reference regenerative braking force limit value TmLmtdn (| TmLmtde | <| TmLmtdn |)
The control proceeds to step S29 to step S31. Basically, the driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn have the smaller absolute value, that is, the regenerative braking is increased. Set the driving wheel speed reference regenerative braking force limit value TmLmtde to be limited to the regenerative braking force limit value TmLmt when the vehicle speed decreases,
At this time, in this embodiment, instead of setting the driving wheel speed reference regenerative braking force limit value TmLmtde as it is to the regenerative braking force limit value TmLmt when the vehicle speed decreases, the driving wheel speed reference regenerative braking force limit value TmLmtde is set as follows. The regenerative braking force limit value obtained by the peak hold is set as the regenerative braking force limit value TmLmt when the vehicle speed decreases.

That is, in step S29, the drive wheel speed reference regenerative braking force limit value TmLmtde is compared with the vehicle speed decrease regenerative braking force limit value TmLmt (previous value) stored in the previous step S32. It is checked whether TmLmtde is larger than the regenerative braking force limit value TmLmt (previous value) when the vehicle speed decreases (| TmLmtde | <| TmLmt (previous value) |).
TmLmtde> TmLmt (previous value) (| TmLmtde | <| TmLmt (previous value) |), that is, the driving wheel speed reference regenerative braking force limit value TmLmtde is the regenerative braking force limit value when the vehicle speed decreases If it is closer to zero than TmLmt (previous value),
In step S30, the regenerative braking force limit value TmLmt when the vehicle speed decreases is updated to the drive wheel speed reference regenerative braking force limit value TmLmtde,
In step S32, the updated vehicle speed decrease regenerative braking force limit value TmLmt is stored as a vehicle speed decrease regenerative braking force limit value TmLmt (previous value).

However, if it is determined in step S29 that TmLmtde ≦ TmLmt (previous value) (| TmLmtde | ≧ | TMLmt (previous value) |), that is, the regenerative braking force limit value TmLmt (previous value) when the vehicle speed decreases is driven. If it is closer to zero than the wheel speed reference regenerative braking force limit value TmLmtde,
In step S31, the regenerative braking force limit value TmLmt when the vehicle speed decreases is maintained at the previous value TmLmt (previous value),
In step S32, the held regenerative braking force limit value TmLmt when the vehicle speed decreases is stored as a regenerative braking force limit value TmLmt (previous value) when the vehicle speed decreases.
Therefore, Step S29 to Step S31 together with Step S27 constitute regenerative braking force limit value selection means in the present invention.

According to the composite brake cooperative control apparatus according to the above-described embodiment,
While the target braking force Tb (step S11) determined according to the driving state and traveling state of the vehicle is realized by the cooperation of the regenerative braking by the motor / generator 6 and the friction braking by the hydraulic brake device (steps S16 and S17). When shifting to friction braking by reducing the regenerative braking force Tm to TmLmt as the vehicle speed decreases,
The driving wheel speed reference regenerative braking force limit value TmLmtde for the above restriction is obtained using the driving wheel speed Vwde as the vehicle speed, and the driven wheel speed reference regenerative braking force limit value TmLmtdn for the above restriction is obtained using the driven wheel speed Vwdn as the vehicle speed. (Step S24),
Relative decrease in absolute value of driving wheel speed reference regenerative braking force limit value TmLmtde relative to the decrease rate of absolute value of driving wheel speed reference regenerative braking force limit value TmLmtde and driven wheel speed reference regenerative braking force limit value TmLmtdn with respect to vehicle speed reduction The difference is such that the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn is larger than the rate as illustrated in FIG.
Of the driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn, the regenerative braking force limit value having a smaller absolute value contributes to the above limit of the regenerative braking force. Therefore, the effects as described below can be achieved.

As will be described in detail with reference to FIG. 5, this figure shows a drive during a shift in which a shift command from the currently selected shift stage to the target shift stage is issued at the instant t1, and the shift to the target shift stage is completed at the instant t2. 6 is an operation time chart during deceleration accompanied by a decrease in vehicle speed as shown by time-series changes in the average wheel speed value Vwde and the average driven wheel speed value Vwdn.
The driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn calculated during the instant t1 to t2 shift are as shown in the figure for the driving wheel speed reference with respect to the decrease in the vehicle speed (Vwde, Vwdn). The absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn is larger than the absolute value decrease rate of the regenerative braking force limit value TmLmtde.

During the shift from the instant t1 to t2, the drive wheel speed reference regenerative braking force limit value TmLmtde also varies as shown in the figure as the drive wheel speed Vwde changes due to this.
However, the absolute value of the drive wheel speed reference regenerative braking force limit value TmLmtde depends on the change in the drive wheel speed reference regenerative braking force limit value TmLmtde due to the change in the drive wheel speed Vwde caused by the shift. The absolute value of the limit value TmLmtdn is never smaller, and the regenerative braking and friction braking distribution is performed as shown by the solid line by limiting the regenerative braking force based on the driven wheel speed reference regenerative braking force limit value TmLmtdn. Become.
For this reason, the change in the drive wheel speed reference regenerative braking force limit value TmLmtde due to the change in the drive wheel speed Vwde caused by the shift causes a smooth transition from regenerative braking to friction braking due to the decrease in vehicle speed (Vwde, Vwdn). The problem of obstructing can be avoided.

On the other hand, although not shown in FIG. 5, the driving wheel speed Vwde is reduced by the braking slip of the driving wheel, so that the driving wheel speed Vwde should finish the regenerative braking and complete the transition to the friction braking. The absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde is smaller than the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn, and the driven wheel speed reference regenerative braking force limit value TmLmtdn described above. Instead of limiting the regenerative braking force based on the above, the regenerative braking force is limited based on the drive wheel speed reference regenerative braking force limit value TmLmtde (steps S29 to S31).
Therefore, when the driving wheel speed Vwde is reduced due to braking slip of the driving wheel and the above low vehicle speed range is reached, the regenerative braking can be surely terminated and the transition to the friction braking can be completed. However, there is no problem that the transition from regenerative braking to friction braking cannot be completed.

In addition, the difference between the absolute value decrease rate of the driving wheel speed reference regenerative braking force limit value TmLmtde and the driven wheel speed reference regenerative braking force limit value TmLmtdn with respect to the decrease in the vehicle speed (the driving wheel speed average value Vwde, the driven wheel speed average value Vwdn) As described above, the driving wheel speed reference regenerative braking force limit value TmLmtde is also changed by the change in the driving wheel speed reference regenerative braking force limit value TmLmtde accompanying the fluctuation of the driving wheel speed average value Vwde caused by the shift of the automatic transmission 4. When the difference between the absolute value of the following does not fall below the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn,
Of the above-described operation effects, the former operation effect can be reliably achieved at any speed change.

In addition, in setting the difference between the absolute value decrease rate of the driving wheel speed reference regenerative braking force limit value TmLmtde and the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn as described above,
By adjusting to decrease the absolute value decrease rate of the drive wheel speed reference regenerative braking force limit value TmLmtde, the absolute value decrease rate of the drive wheel speed reference regenerative braking force limit value TmLmtde to the vehicle speed decrease is changed to the driven wheel speed reference regenerative control to the vehicle speed decrease. It may be smaller than the absolute value decrease rate of the power limit value TmLmtdn,
By adjusting to increase the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn, the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn to the vehicle speed decrease becomes the driving wheel speed reference regenerative system to the vehicle speed decrease. It may be larger than the absolute value decrease rate of the power limit value TmLmtde,
By combining the adjustment to decrease the absolute value decrease rate of the driving wheel speed reference regenerative braking force limit value TmLmtde and the adjustment to increase the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value TmLmtdn, these absolute value decrease rates You may set the above difference in between,
In either case, the above-mentioned former operation and effect can be reliably achieved.

In this embodiment, the driving wheel speed Vwde is greatly reduced at the moment t3 in FIG. 6 due to braking slip of the driving wheel, and the absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde is the driven wheel speed reference regenerative braking. When the power limit value TmLmtdn is smaller than the absolute value, the regenerative braking force is limited based on the drive wheel speed reference regenerative braking force limit value TmLmtde as described above (steps S27 to S31).
At this time, the driving wheel speed reference regenerative braking force limit value TmLmtde is not set to the regenerative braking force limit value TmLmt when the vehicle speed is reduced as it is, but the driving wheel speed reference regenerative braking force limit value TmLmtde is set as described above for step S29 and step S30. Since the regenerative braking force limit value obtained by holding the peak at the same time is set to the regenerative braking force command value Tm as the regenerative braking force limit value TmLmt when the vehicle speed decreases, the following operational effects can be achieved.

When the driving wheel speed Vwde is greatly reduced as shown at the instant t3 in FIG. 6, the absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde is larger than the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn as shown in the figure. Becomes smaller.
However, after that, the driving wheel speed Vwde recovers as shown after the instant t3 in FIG. 6 by eliminating the driving wheel braking slip, and the absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde is as shown in the figure. Even if the braking force limit value TmLmtdn is larger than the absolute value, the regenerative braking force limit value obtained by holding the driving wheel speed reference regenerative braking force limit value TmLmtde at the peak value (nearest zero) of the instantaneous t3 is the vehicle speed. This is used to determine the regenerative braking force command value Tm as the regenerative braking force limit value TmLmt at the time of decrease.

  Therefore, as indicated by the solid line after the instant t3, the regenerative braking force command value Tm is maintained at the peak value at the instant t3 even if the absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde increases as the driving wheel speed Vwde recovers. After the instant t4 when the absolute value of the regenerative braking force command value Tm becomes equal to or greater than the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn as time elapses, the regenerative braking force command value Tm becomes the driven wheel speed reference regenerative control. Limited to power limit value TmLmtdn.

With the above cooperative control, in the present embodiment, the driving wheel speed Vwde greatly decreases at the driving wheel braking slip as shown at the instant t3 in FIG. 6, and the absolute value of the driving wheel speed reference regenerative braking force limit value TmLmtde is Even if the driving wheel speed reference regenerative braking force limit value TmLmtdn is smaller than the absolute value, the driving wheel speed Vwde recovers immediately after the instant t3 in FIG. If the absolute value of the limit value TmLmtde is larger than the absolute value of the driven wheel speed reference regenerative braking force limit value TmLmtdn as shown in the figure,
In response to this, the regenerative braking force is not increased, and the above-described effects can be achieved while eliminating the adverse effect of frequent increase / decrease in regenerative braking accompanying a temporary change in the driving wheel speed Vwde. .

  In this embodiment, the average wheel speed Vwde of the left and right drive wheels 3RL and 3RR is used as the drive wheel speed, and the average wheel speed Vwdn of the left and right driven wheels 2FL and 2FR is used as the driven wheel speed. Thus, even when one of the 3RRs generates a braking slip or when one of the left and right driven wheels 2FL, 2FR generates a braking slip, the above-described operation and effect can be reliably achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic plan view showing a power train of a front engine / rear wheel drive hybrid vehicle including a composite brake cooperative control device according to an embodiment of the present invention, together with its control system. 3 is a flowchart showing a main routine related to cooperative control of a composite brake executed by an integrated controller in FIG. FIG. 3 is a flowchart showing a subroutine related to a calculation process of a regenerative braking force limit value at the time of vehicle speed decrease calculated in the main routine of FIG. 2; FIG. 4 is a characteristic diagram showing change characteristics of a driving wheel speed reference regenerative braking force limit value and a driven wheel speed reference regenerative braking force limit value calculated in the subroutine of FIG. 3; FIG. 5 is an operation time chart showing cooperative control during gear shifting in the embodiment shown in FIGS. 5 is an operation time chart showing cooperative control at the time of driving wheel braking slip in the embodiment shown in FIGS.

Explanation of symbols

1 engine
2FL, 2FR Left and right front wheels (left and right driven wheels)
3RL, 3RR Left and right rear wheels (left and right drive wheels)
4 Automatic transmission
6 Motor / generator (motor)
7 First clutch
9 Second clutch
11 Integrated controller
12 Engine rotation sensor
13 Motor / generator rotation sensor
14 Transmission input rotation sensor
15 Transmission output rotation sensor
16 Accelerator position sensor
17 Storage state sensor
18 Master cylinder hydraulic pressure sensor
21 Wheel speed sensor group
31 battery
32 Engine controller
33 Motor / generator controller
34 Inverter
35 Brake controller
36 1st clutch controller
37 1st clutch engagement pressure control unit
38 Transmission controller
39 Second clutch engagement pressure control unit

Claims (7)

An electric vehicle equipped with at least a motor / generator as a prime mover and capable of drivingly coupled between the motor / generator and a front wheel or a rear wheel which is a driving wheel by a transmission,
The target braking force determined according to the driving state and traveling state of the vehicle is realized by cooperation of the regenerative braking by the motor / generator and the friction braking by the brake device, but the regenerative braking force is limited and reduced as the vehicle speed decreases. In the composite brake of a vehicle that is shifted to friction braking by
A driving wheel speed reference regenerative braking force limit value for the restriction is obtained using the driving wheel speed of the front wheel or rear wheel as the driving wheel as the vehicle speed, and the driven wheel speed of the rear wheel or front wheel as the driven wheel is determined as the vehicle speed. As follows, the driven wheel speed reference regenerative braking force limit value for the limitation is obtained,
Relative to the decrease in the absolute value of the driving wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value with respect to the decrease in vehicle speed, the relative decrease in the absolute value of the driving wheel speed reference regenerative braking force limit value Regenerative braking force limit value calculating means for giving a difference such that the absolute value decrease rate of the driven wheel speed reference regenerative braking force limit value is increased;
Of the driving wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value obtained by the means, the regenerative braking force limit value having a smaller absolute value is used as a regenerative system that contributes to the limitation of the regenerative braking force. A combined brake cooperative control device comprising a power limit value selection means. In the cooperative control device of the composite brake according to claim 1,
The regenerative braking force limit value calculating means adjusts the driving wheel speed reference regenerative braking force limit value to obtain an absolute value reduction ratio of the driving wheel speed reference regenerative braking force limit value with respect to a decrease in vehicle speed, and the driven wheel with respect to a decrease in vehicle speed. A combined brake cooperative control device characterized in that it is smaller than the absolute value lowering rate of the speed reference regenerative braking force limit value. In the cooperative control device of the composite brake according to claim 1,
The regenerative braking force limit value calculating means adjusts the driven wheel speed reference regenerative braking force limit value to determine the absolute value decrease ratio of the driven wheel speed reference regenerative braking force limit value with respect to the vehicle speed decrease, and the drive wheel with respect to the vehicle speed decrease. A combined brake cooperative control device characterized in that it is larger than the absolute value reduction rate of the speed reference regenerative braking force limit value. In the cooperative control device of the composite brake according to any one of claims 1 to 3,
The regenerative braking force limit value selection means selectively uses a driving wheel speed reference regenerative braking force limit value and a driven wheel speed reference regenerative braking force limit value, which contribute to the limitation of the regenerative braking force, during shifting of the transmission. A combined brake cooperative control device characterized by being a thing. In the cooperative control device of the composite brake according to claim 4,
The relative difference between the absolute value lowering ratios of the driving wheel speed reference regenerative braking force limit value and the driven wheel speed reference regenerative braking force limit value with respect to a decrease in vehicle speed is the driving wheel speed reference regeneration due to the shift of the transmission. Coordination of the composite brake, wherein the absolute value of the driving wheel speed reference regenerative braking force limit value does not fall below the absolute value of the driven wheel speed reference regenerative braking force limit value even when the braking force limit value changes Control device. In the cooperative control device of the composite brake according to any one of claims 1 to 5,
When the driving wheel speed reference regenerative braking force limit value is smaller than the driven wheel speed reference regenerative braking force limit value by absolute value comparison, the regenerative braking force limit value selection means selects the driving wheel speed reference regenerative braking force. A cooperative brake cooperative control device characterized in that a value close to zero of a limit value contributes to the limit of regenerative braking. In the cooperative control device of the composite brake according to any one of claims 1 to 6,
A combined brake cooperative control apparatus, wherein an average wheel speed value of all driven wheels is used as the driving wheel speed, and an average wheel speed value of all driven wheels is used as the driven wheel speed.

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