JP3763240B2 - Vehicle braking device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a braking device for a vehicle, and more particularly, to a braking method for adding a regenerative braking force to a friction braking force according to a depression pressure of a brake pedal.
[0002]
[Prior art]
In a vehicle that uses both friction braking and regenerative braking, the friction brake device is provided with a pressure reducing function to reduce the wheel cylinder hydraulic pressure of the friction brake device by the amount of regenerative braking and generate a braking force according to the depression pressure of the brake pedal. A braking method (hereinafter referred to as a regenerative cooperative control method) and a braking method (hereinafter referred to as an additional regenerative control method) that generates a friction braking force according to the depression pressure of the brake pedal and adds the regenerative braking amount to the friction braking force. Called).
[0003]
In the latter addition regenerative control method, when the accelerator pedal is released, a regenerative braking force corresponding to the engine braking force corresponding to the shift position of the transmission is generated, and when the brake pedal is depressed, the engine is There is a technique in which a predetermined regenerative braking force is added to the friction braking force corresponding to the regenerative braking force corresponding to the braking force and the depression pressure of the brake pedal (see, for example, Japanese Patent Laid-Open No. 06-070406). In this additional regenerative control method, a constant additional regenerative braking force is set according to the shift position of the transmission so as not to impair the stability of the vehicle.
[0004]
[Problems to be solved by the invention]
However, in the above-described additional regenerative braking device, a constant additional regenerative braking force is set according to the shift position of the transmission, so that more regenerative braking force can be obtained while ensuring the stability of the vehicle. There is a problem that the regenerative braking force is not increased even in a low vehicle speed range, and the recoverable energy is wasted.
[0005]
An object of the present invention is to recover the running energy of a vehicle without waste during the additional regenerative braking.
[0006]
[Means for Solving the Problems]
The present invention will be described with reference to FIGS. 1 and 3 showing an embodiment.
(1) The invention of claim 1 includes a motor 1 for generating a regenerative braking force, a charging means 3 for charging the battery 4 with regenerative electric power of the motor 1, and a friction braking force (Tf) according to the depression pressure of the brake pedal. Friction braking means for generating brake, brake detection means 8 for detecting depression of the brake pedal, vehicle speed detection means 9 for detecting the vehicle speed Vsp, and charging means 3 when the brake detection means 8 detects depression of the brake pedal. And a control means 5 for generating a braking force (Te + Tm) obtained by adding a predetermined regenerative braking force (Tm) to a regenerative braking force (Te) corresponding to the engine braking force from the motor 1. When the vehicle speed Vsp becomes equal to or less than the predetermined value α, the control means 5 adds the regenerative braking force (Te) corresponding to the engine braking force, the friction braking force (Tf), and the additional regeneration. Increasing the power sum of the (Tm) (Te + Tf + Tm) is the stability limit braking force of the vehicle (beta) plus regenerative braking force within a range not exceeding (Tm).
(2) The vehicle braking device according to claim 2 includes an anti-lock brake system (ABS) device 10 that prevents the wheels from locking during braking, and is added when the ABS device 10 is held by the control means 5. The regenerative braking force (Tm) is reduced.
[0007]
In the section of the means for solving the above-described problem, a diagram of an embodiment is used for easy understanding of the description. However, the present invention is not limited to the embodiment.
[0008]
【The invention's effect】
(1) According to the invention of claim 1, when the depression of the brake pedal is detected, a braking force obtained by adding a predetermined regenerative braking force to the regenerative braking force corresponding to the engine braking force is generated, and the vehicle speed is a predetermined value. When the following is reached, the regenerative braking force equivalent to the engine braking force, the friction braking force, and the additional regenerative braking force are increased so that the total regenerative braking force does not exceed the stability limit braking force of the vehicle. Therefore, the traveling energy that can be recovered in the low vehicle speed range can be recovered without being wasted while ensuring the stability of the vehicle during braking.
(2) According to the invention of claim 2, when the ABS device is in the holding state, the additional regenerative braking force is reduced. In addition to the above effect of claim 1, early operation of the ABS device can be prevented. The amount of travel energy recovered can be increased by the amount delayed in operation.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment in which the present invention is applied to a hybrid vehicle equipped with a belt-type or toroidal-type continuously variable transmission and an ABS device will be described. This hybrid vehicle travels by either one or both of the engine and motor during driving, and decelerates and stops the vehicle by braking force of the friction brake device and regenerative braking force of the motor during braking. The present invention is not limited to a hybrid vehicle, but can be applied to an electric vehicle using only a motor as a travel drive source.
[0010]
FIG. 1 is a diagram showing a configuration of an embodiment. In addition, illustration of the clutch interposed between the engine and the motor and the continuously variable transmission is omitted.
The motor 1 is connected to the driving wheel 2 via a continuously variable transmission (not shown), and generates driving force and braking force. The motor 1 can be a direct current motor in addition to various alternating current motors such as a synchronous type and an induction type. The inverter 3 converts the DC power of the battery 4 into AC power and supplies it to the motor 1, and converts the AC power regenerated by the motor 1 into DC power and supplies it to the battery 4. In addition, when using a direct current motor for the motor 1, a DC-DC chopper is used instead of an inverter.
[0011]
The vehicle controller 5 includes peripheral parts such as a microcomputer and a memory, and calculates a drive torque command value, a regenerative braking torque command value, a maximum allowable regenerative torque value, and the like based on the state of the vehicle, the state of the battery 4, and the like. The controller 6 is controlled. The motor controller 6 is composed of peripheral parts such as a microcomputer and a memory, and controls the inverter 3 based on the drive torque command value and the regenerative braking torque command value from the vehicle controller 5 to control the drive torque and the regenerative torque of the motor 1. To do.
[0012]
An accelerator sensor 7, a brake pedal switch 8, a vehicle speed sensor 9, an ABS device 10, a battery sensor 11, and the like are connected to the vehicle controller 5. The accelerator sensor 7 detects the depression amount of the accelerator pedal, and the brake switch 8 detects the depression state of the brake pedal. Further, the vehicle speed sensor 9 detects the traveling speed Vsp of the vehicle. The ABS device 10 is a device that controls the braking force of a friction brake device (not shown) to prevent the wheels from being locked during braking, and sends information on the operating state to the vehicle controller 5. The battery sensor 11 detects the charge state SOC and temperature of the battery 4.
[0013]
FIG. 2 is a flowchart illustrating a regenerative braking control program according to an embodiment. The operation of the embodiment will be described with reference to this flowchart.
The microcomputer of the vehicle controller 5 executes this regenerative braking control program every predetermined time, for example, 10 msec. In step 1, the amount of depression of the accelerator pedal is detected by the accelerator sensor 7, and when the amount of depression is substantially 0, that is, when the accelerator pedal is released, the process proceeds to step 2, and when the accelerator pedal is depressed, the process proceeds to step 9. move on. When the accelerator pedal is depressed, the drive mode is selected. In step 9, the regenerative torque command value is set to 0, the process proceeds to step 8, and the regenerative torque command value (0 in this case) is output to the motor controller 6.
[0014]
On the other hand, when the accelerator pedal is released, in step 2, a regenerative braking torque (hereinafter referred to as an emblem regenerative torque or simply referred to as an emblem regenerative torque) Te corresponding to the engine brake torque is calculated. Specifically, a map of the emblem regeneration torque with respect to the motor rotation speed corresponding to the engine brake torque characteristic map with respect to the engine rotation speed is preset and stored, and the emblem regeneration torque corresponding to the current rotation speed of the motor 1 is stored. Te is calculated.
[0015]
In step 3, it is determined whether or not the additional regeneration is permitted based on the state of the vehicle. Here, the vehicle state includes the vehicle speed and various abnormality information. For example, the vehicle speed is approximately 5 km / h or less, that is, the regeneration is prohibited at the creep speed. In addition, when an abnormality is detected in the motor 1, the inverter 3, the battery 4, or the like, the additional regeneration is prohibited. In step 4, it is confirmed whether or not the additional regeneration is permitted. If permitted, the process proceeds to step 5, and if prohibited, the process proceeds to step 6. If the additional regeneration is permitted, an additional regeneration control calculation routine shown in FIGS. 5 and 6 is executed in step 5 to calculate an additional regeneration torque (hereinafter referred to as additional regeneration) Tm. On the other hand, if the additional regeneration is prohibited, the additional regeneration amount is set to 0 in step 6 and the process proceeds to step 7.
[0016]
In step 7, the emblem regeneration Te calculated in step 2 and the additional regeneration Tm calculated in step 5 are added to obtain a regenerative torque command value. In the following step 8, the regenerative torque command value is output to the motor controller 6. The motor controller 6 controls the inverter 3 to output the regenerative torque from the motor 1 according to the regenerative torque command value output from the vehicle controller 5.
[0017]
Here, an additional regeneration control method according to an embodiment will be described with reference to FIG.
When the accelerator pedal is released at time t1, the clutch interposed between the engine and the motor 1 is released, the engine is disconnected from the drive system of the vehicle, and the emblem regeneration torque Te is generated by the motor 1. The emblem regeneration torque Te increases as the vehicle speed Vsp decreases as shown in FIG.
[0018]
Further, when the brake pedal is depressed at time t2, a friction brake device (not shown) generates a friction brake torque (hereinafter referred to as a friction brake) Tf corresponding to the depression pressure of the brake pedal. At the same time, a predetermined amount of additional regenerative torque (hereinafter referred to as additional regenerative torque) Tm is generated from the motor 1. The additional regeneration amount Tm is a constant amount irrespective of the vehicle speed Vsp, and the total braking torque after addition (Te + Tf + Tm) is an amount that does not exceed the vehicle stability limit braking torque β.
[0019]
By the way, in a normal vehicle, driving power generated from a driving source such as an engine or a motor is driven via a belt-type or toroidal-type continuously variable transmission, or a stepped transmission such as an automatic transmission or a manual transmission. To communicate. Whichever type of transmission is used, the gear ratio is large in the low vehicle speed range, and the rotational speed of the transmission input shaft is higher than the rotational speed of the output shaft. Conversely, the gear ratio is small in the high vehicle speed range, and the rotational speed of the transmission input shaft is lower than the rotational speed of the output shaft. This relationship is the same in the drive mode in which the vehicle is driven by one or both of the engine and the motor, or in the regeneration mode in which the running energy of the vehicle is recovered by the motor. Therefore, in the regeneration mode, the vehicle speed becomes lower. The motor is rotated at high speed from the drive wheel side, and the back electromotive voltage of the motor increases. As the back electromotive voltage of the motor increases, the regenerative amount of running energy increases, so that the additional regeneration Tm can be increased as the vehicle speed decreases.
[0020]
FIG. 4 is a diagram illustrating a relationship between the vehicle speed and the additional regeneration possible amount in the hybrid vehicle according to the embodiment.
As shown in FIG. 4, regardless of the state of acceptable power of the battery 4, when the vehicle 4 becomes lower than a specific vehicle speed α, the additional regenerative amount suddenly increases.
[0021]
Therefore, in this embodiment, as shown in FIG. 3, in the range where the vehicle speed Vsp exceeds α, an additional regeneration portion Tm that does not exceed the vehicle stability limit braking torque β is set, and when the vehicle speed Vsp becomes less than α. (Time t3) The regeneration amount Tm is increased in the range not exceeding the vehicle limit braking torque β. As a result, the travel energy that can be recovered in the low vehicle speed range can be recovered without being wasted. Since the vehicle speed α varies depending on the rated capacity of the battery 4, the rated output of the motor 1, and the like, it is desirable to set an optimal value through actual vehicle experiments.
[0022]
FIG. 5 and FIG. 6 are flowcharts showing an addition regeneration control calculation routine. With reference to this flowchart, the addition regeneration control according to the embodiment will be described.
In step 11, based on the state of charge SOC, the temperature, and the degree of deterioration of the battery 4, a maximum additional regeneration possible amount Tmmax is obtained by the following equation.
[Expression 1]
Tmmax = {(SOCmax−SOC) * Ka * Kb} −Te
In the above equation, SOCmax is the maximum charge amount of the battery 4, and SOC is the current charge amount detected by the battery sensor 11. Ka is a temperature coefficient of the battery 4 and converts the current chargeable amount (SOCmax−SOC) into the regenerative torque amount of the motor 1. Kb is a deterioration coefficient of the battery 4.
[0023]
In step 12, it is confirmed whether or not the flag F indicating the start of the additional regeneration control is set (1), that is, whether or not the additional regeneration control has already been started. If the additional regeneration control has not yet been started, the process proceeds to step 13, and if already started, the process proceeds to step 17. In the example shown in FIG. 3, the additional regeneration control is started from the time when the brake pedal is depressed at time t2.
[0024]
When the brake pedal is depressed to start the additional regeneration control, the total value (Te + Tf + Tmmax) of the emblem regeneration portion Te, the friction brake portion Tf and the maximum additional regeneration possible amount Tmmax calculated in step 11 is determined in Step 13. Check if the stability limit braking torque β is exceeded. When the total braking torque value (Te + Tf + Tmmax) exceeds the stability limit braking torque β, the routine proceeds to step 14, and a value that does not exceed the stability limit braking torque β is set as the additional regeneration torque Tm of the motor 1. That is,
[Expression 2]
Tm = β-Te-Tf
Then, the additional regeneration control start flag F is set and the routine proceeds to step 16 where the gradient at the rise of the additional regeneration torque Tm is controlled to a predetermined value A and the program returns to the program shown in FIG. The slope of the additional regeneration torque Tm is set to a value that does not cause the occupant to feel an impact or discomfort.
[0025]
On the other hand, if the total value (Te + Tf + Tmmax) of the emblem regeneration portion Te, the friction brake portion Tf, and the maximum additional regeneration possible amount Tmmax is equal to or less than the vehicle stability limit braking torque β, the process proceeds to step 15 and the maximum additional regeneration obtained in step 11 is performed. Even if the possible amount Tmmax is generated by the motor 1, the vehicle stability limit braking torque β is not exceeded, so the maximum regenerative amount Tmmax is set to the additional regenerative torque Tm of the motor 1. Then, the additional regeneration control start flag F is set and the routine proceeds to step 16, where the inclination at the rising of the additional regeneration torque Tm is controlled to the predetermined value A as described above, and the program returns to the program shown in FIG.
[0026]
In step 12, the additional regeneration control is already started and the first additional regeneration torque Tm is calculated. If the motor 1 is performing the additional regeneration operation in accordance with the initial additional regeneration torque Tm, the current vehicle speed Vsp is determined in step 17. Confirms whether the vehicle speed is equal to or lower than the vehicle speed α described above. If the vehicle speed Vsp is not less than or equal to α, the added regenerative torque Tm cannot be increased, so the processing is terminated and the program returns to the program shown in FIG.
[0027]
On the other hand, if the current vehicle speed Vsp is less than or equal to α, the process proceeds to step 21 to check whether or not the current additional regeneration torque Tm is larger than the latest maximum additional regeneration possible amount Tmmax calculated in step 11 this time. . If the current additional regeneration torque Tm is larger than the maximum additional regeneration possible amount Tmmax calculated this time, the additional regeneration torque Tm cannot be increased any more, so the processing is terminated and the program returns to the program shown in FIG.
[0028]
If the current addition regenerative torque Tm is less than or equal to the maximum addition regenerative amount Tmmax calculated this time, the process proceeds to step 22 to reset the maximum addition regenerative amount Tmmax calculated this time to the addition regenerative torque Tm and increase the addition regenerative torque Tm. To do. In the subsequent step 23, since the additional regenerative torque Tm is increased, it is confirmed whether or not the total value (Te + Tf + Tm) of the emblem regenerative component Te, the friction brake component Tf, and the additional regenerative torque Tm is equal to or less than the vehicle stability limit braking torque β. . If the total value (the total value (Te + Tf + Tm) is equal to or less than the vehicle stability limit braking torque β, the process proceeds to step 24, the gradient when increasing the additional regenerative torque Tm is controlled to the predetermined value B, and the process returns to the program shown in FIG. Note that it is desirable that the regenerative torque gradient B when increasing the additional regenerative torque Tm be smaller than the above-described gradient A of the rise at the start of the additional regenerative control so that the additional regenerative torque Tm is increased smoothly.
[0029]
On the other hand, if the total value (Te + Tf + Tm) is larger than the vehicle stability limit braking torque β, the process proceeds to step 25, and the maximum value that does not exceed the vehicle stability limit braking torque β is set as the additional regeneration torque Tm by the following equation.
[Equation 3]
Tm = (β-Te-Tf)
Then, the process proceeds to step 24, and the gradient when increasing the additional regeneration torque Tm is controlled to a predetermined value B, and the process returns to the program shown in FIG.
[0030]
As described above, when the depression of the brake pedal is detected, a regenerative braking torque (Te + Tm) obtained by adding a predetermined regenerative braking torque Tm to the emblem regenerative braking torque Te is generated, and the vehicle speed Vsp becomes a predetermined value α or less. Since the regenerative braking torque Tm, the friction braking torque Tf, and the additional regenerative braking torque Tm (Te + Tf + Tm) are within the range that does not exceed the vehicle stability limit braking torque β, the additional regenerative braking torque Tm is increased. The traveling energy that can be recovered in the low vehicle speed range can be recovered without wasting it while ensuring the stability of the vehicle during braking.
[0031]
Next, a method for increasing the energy recovery amount by preventing early operation of the ABS device 10 by the addition regeneration control will be described.
The ABS device 10 obtains the slip amount based on the peripheral speed of the drive wheel 2 and the vehicle body speed, and determines whether or not the drive wheel 2 has a locking tendency. If the slip amount is greater than or equal to the predetermined value, it is determined that the drive wheel 2 is in a locking tendency, and the state shifts to the ABS holding state. If the slip amount remains above a predetermined value after a predetermined time has passed since the ABS was maintained, the state transits to the ABS pressure reduction (ABS operation) state, and if the slip amount is less than the predetermined value, the return (ABS inactive) ) Transition to the state.
[0032]
When a transition is made from the ABS holding state to the ABS pressure-reducing state, as shown in FIG. 7, the added regeneration Tm is reduced to 0, and the hydraulic pressure in the wheel cylinders (not shown) of the drive wheels 2 is reduced. When the slip amount decreases, the hydraulic pressure is increased again, and thereafter, the ABS device 10 is operated by repeatedly depressurizing and increasing the pressure of the wheel cylinder.
[0033]
By the way, when the slip amount of the drive wheel 2 exceeds the predetermined value and transitions to the ABS holding state, if the driving wheel 2 continues to be locked as it is, the ABS pressure reduction state is surely reached, but as shown in FIG. Immediately after becoming, it is possible to delay the drive wheel 2 from being locked by reducing the added regenerative torque Tm. As a result, early operation of the ABS device 10 can be prevented, and the amount of travel energy recovered can be increased by the amount of delay in the ABS operation.
[0034]
FIG. 9 is a flowchart showing a control routine for delaying the ABS operation by the addition regeneration control. This ABS control routine can be executed before the addition regeneration control calculation routine shown in FIGS. 5 and 6 is terminated and the program returns to the program shown in FIG.
In step 31, it is confirmed from the information from the ABS device 10 whether the ABS is held. When the ABS is maintained, the routine proceeds to step 32, where a predetermined amount γ is subtracted from the current additional regeneration torque Tm to reduce the additional regeneration torque Tm. On the other hand, when it is not in the ABS holding state, the process proceeds to step 33, and it is confirmed from the information from the ABS device 10 whether the ABS is in a decompressed state. When the ABS device 10 is already operating (ABS pressure reduction), the routine proceeds to step 34 where 0 is set as the additional regenerative torque Tm.
[0035]
Thus, when the ABS device is in the holding state, the additional regenerative braking Tm is reduced, so that the early operation of the ABS device can be prevented, and the amount of travel energy recovered can be increased by the amount of delay of the ABS operation.
[0036]
In the configuration of the above embodiment, the motor 1 is the motor, the inverter 3 is the charging means, the friction brake device (not shown) is the friction braking means, the brake pedal switch 8 is the brake detecting means, and the vehicle speed sensor 9 is the vehicle speed. The vehicle controller 5 constitutes a control means, and the ABS device 10 constitutes an ABS device.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment.
FIG. 2 is a flowchart showing a regenerative braking control program according to one embodiment.
FIG. 3 is a diagram for explaining an addition regeneration control method according to an embodiment;
FIG. 4 is a diagram showing a possible additional regeneration amount with respect to the vehicle speed.
FIG. 5 is a flowchart illustrating an addition regeneration control calculation routine according to one embodiment.
FIG. 6 is a flowchart illustrating an addition regeneration control calculation routine according to an embodiment, following FIG. 5;
FIG. 7 is a diagram for explaining addition regeneration control during ABS operation.
FIG. 8 is a diagram for explaining an addition regeneration control at the time of holding an ABS.
FIG. 9 is a flowchart showing a control routine for delaying the ABS operation by addition regeneration control.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Motor 2 Drive wheel 3 Inverter 4 Battery 5 Vehicle controller 6 Motor controller 7 Accelerator sensor 8 Brake pedal switch 9 Vehicle speed sensor 10 ABS apparatus 11 Battery sensor

Claims (2)

A motor that generates regenerative braking force;
Charging means for charging the battery with regenerative power of the motor;
Friction braking means for generating a friction braking force according to the depression pressure of the brake pedal;
Brake detecting means for detecting depression of the brake pedal;
Vehicle speed detection means for detecting the vehicle speed;
Control means for controlling the charging means to generate a braking force obtained by adding a predetermined regenerative braking force to the regenerative braking force corresponding to the engine braking force from the motor when the brake detection means detects the depression of the brake pedal. A vehicle braking device comprising:
When the vehicle speed falls below a predetermined value, the control means is such that the total value of the regenerative braking force equivalent to the engine braking force, the friction braking force, and the additional regenerative braking force does not exceed the vehicle stability limit braking force. A braking device for a vehicle, wherein the additional regenerative braking force is increased within a range. The vehicle braking device according to claim 1,
It has an ABS (Anti-lock Brake System) device that prevents the wheels from locking when braking,
The vehicle braking device according to claim 1, wherein the control means reduces the additional regenerative braking force when the ABS device is in a holding state.

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