JP3160723B2 - Electric vehicle braking system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driven wheel that can be hydraulically braked by operating a brake operator, and is connected to and driven by a motor using a battery as an energy source. normally the regenerative braking can be driving wheels from causing exceed the regenerative braking force of the driving wheel with respect to the ideal distribution characteristic of the braking force of the driven wheel and the driving wheel regenerative Yu <br/> destination mode along said ideal distribution characteristic And a control unit for controlling switching to the mode. In this specification, "the driven wheel and the drive
The ideal distribution characteristics of the braking force of the wheels "
Ideal distribution characteristic of wheel braking force, that is,
The rate of change of the rear wheel braking force increases as the front wheel braking force increases.
Distribution characteristics that are gradually reduced ”
It refers to the ideal distribution characteristic of the driving wheel braking force
Yes, for example after the front wheel is the driven wheel and the rear wheel is the drive wheel
In a vehicle such as the embodiment described above, as shown by a broken line in FIG.
Change rate of the braking force of the driving wheel with respect to the braking force of the driven wheel
That gradually decreases as the braking force of the driven wheel increases
Characteristics.

[0002]

2. Description of the Related Art Conventionally, in a vehicle running by an electric motor using a battery as an energy source, a driving wheel is regeneratively braked to charge the battery with electric power generated by the motor, and the travelable distance of the vehicle per charge Are known (for example, Japanese Patent Publication No. 56-62).
04, JP-B-49-28933).

[0003]

THE INVENTION Problems to be Solved] Such in the electric vehicle to maximize energy recovery efficiency by the regenerative braking, regenerative priority is normally to exceed the regenerative braking force of the drive wheels with respect to the ideal distribution characteristic of the braking force It is conceivable that braking is performed according to the mode and, if necessary, braking is performed in the normal mode according to the ideal distribution characteristics.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle braking device capable of switching between the above-mentioned braking modes, in which the mode switching control is appropriately performed in accordance with the magnitude of the road surface friction coefficient.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a driven wheel which can be hydraulically braked by operating a brake operator and a motor which is connected to and driven by a motor using a battery as an energy source. the hydraulic braking and regenerative braking can be driving wheels from causing exceed the regenerative braking force of the driving wheel with respect to the ideal distribution characteristic of the braking force of the driven wheel and the driving wheel regenerative priority mode by the operation of the brake operation element A control device for controlling switching to a normal mode according to an ideal distribution characteristic, comprising: a braking device for an electric vehicle, wherein the switching from the regenerative priority mode to the normal mode by the control device is performed by slipping a driven wheel or a driving wheel. The first feature is that the operation is performed when the amount exceeds a predetermined threshold.

According to a second aspect of the present invention, in addition to the first feature, the normal mode selected when the slip amount exceeds a first threshold value is executed only by hydraulic braking. A second feature is that the normal mode selected when the slip amount exceeds a second threshold value smaller than the first threshold value is executed by using both regenerative braking and hydraulic braking. I do.

According to a third aspect of the present invention, in addition to the second feature, when the slip amount exceeds the second threshold for a predetermined time, regenerative braking and hydraulic braking are performed. A third feature is that a switch is made from a normal mode in which is used together with a normal mode in which only hydraulic braking is performed.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 23 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of an electric vehicle provided with the braking device, FIG. 2 is a block diagram of a control system, and FIG. 3 is a braking mode. 4 to 23 are a flowchart, a graph, and a time chart for explaining the operation.

As shown in FIG. 1, this electric vehicle has a pair of front wheels Wf as driven wheels and a pair of rear wheels W as driving wheels.
r, a rear wheel Wr is connected to an electric motor 2 using a battery 1 as an energy source via a four-speed forward transmission 3 and a differential 4. A PDU (power drive unit) 5 is interposed between the battery 1 and the motor 2 to control the driving of the motor 2 by the battery 1 and to charge the battery 1 with electric power generated by the motor 2 in association with regenerative braking. Control. The PDU
5 and transmission 3 are motor transmission control E
This motor is connected to a CU (electronic control unit) 6.
The mission control ECU 6 is connected to a brake ECU (electronic control unit) 7.

A master cylinder 9 operated by the brake pedal 8 is connected to a brake cylinder 13f of each front wheel Wf and a brake cylinder 13r of each rear wheel Wr via a modulator 12 connected to an accumulator 11 accumulated by a hydraulic pump 10. Connected to. Modulator 12
Has a two-channel ABS (anti-lock brake system) control valve 14f for the front wheels and a one-channel ABS control valve 14r for the rear wheels, and when the front wheels Wf and the rear wheels Wr tend to lock, they are turned off. The brake hydraulic pressure transmitted to the brake cylinders 13f and 13r is reduced.

An oil passage connecting the master cylinder 9 and the modulator 12 has a brake cylinder 13f for the front wheel Wf.
A hydraulic control valve comprising an ON / OFF valve 15f and a differential pressure valve 16f for controlling the brake hydraulic pressure transmitted to the rear wheel Wr is different from an ON / OFF valve 15r for controlling the brake hydraulic pressure transmitted to the brake cylinder 13r of the rear wheel Wr. A hydraulic control valve composed of a pressure valve 16r is interposed.

The front wheel ON / OFF valve 15f is a normally open / closed valve driven by a solenoid, and shuts off communication between the master cylinder 9 and the modulator 12 as required. The front-wheel differential pressure valve 16f is provided in a bypass oil passage that bypasses the ON / OFF valve 15f, and is urged in the valve closing direction by a spring 17f.
f, and a linear solenoid 19f for adjusting the set load of the spring 17f. ON / OF for rear wheel
The F valve 15r and the differential pressure valve 16r have the same structure as that for the front wheels. The bypass oil passage is provided with a one-way valve that regulates transmission of hydraulic pressure from the master cylinder 9 to the modulator 12 and allows transmission of hydraulic pressure from the modulator 12 to the master cylinder 9.

As is clear from FIG. 2 together,
The brake ECU 7 includes a remaining battery capacity meter 20 and a battery temperature sensor 21 provided for the battery 1, a motor rotation speed sensor 22 for detecting the rotation speed of the motor 2, and wheel speeds provided for the front wheels Wf and the rear wheels Wr. Sensor 23
A brake pedal depression force sensor 24 provided on the brake pedal 8, an accelerator opening sensor 25 provided on an accelerator pedal 28, a steering sensor 26 provided on a steering wheel 29, and provided on the accumulator 12. A hydraulic control valve connected to an accumulator pressure sensor 27 and controlled based on output signals thereof; a hydraulic control valve including the ON / OFF valves 15f and 15r and differential pressure valves 16f and 16r; ABS control valve 14f, 1
4r is connected.

The PDU 5 for controlling the battery 1 and the motor 2 and the transmission 3 are connected to a motor / mission control ECU 6 which operates in response to a regenerative braking command and a mission shift command from the brake ECU 7. .

Next, an outline of each braking mode will be described with reference to FIG.

The front wheel W in a vehicle equipped with the present braking device
There are three types of braking modes for f and the rear wheel Wr: [mode 3], [mode 2], and [mode 1], and any one of them is selected by the initial determination to perform braking in a predetermined mode. The mode is changed during braking due to a change in the operating state. [ Mode 3 ] This mode is selected in a normal operation state. That is, this is selected when the regenerative braking system is functioning normally and neither during sudden braking nor during steering. [Mode 3] is a mode in which the front wheel Wf is braked by hydraulic pressure and the rear wheel Wr is braked by hydraulic pressure and regeneration. When the brake pedal 8 is depressed, only the rear wheel Wr is regeneratively braked and hydraulic braking of the front wheel Wf is performed. Not done.
When the braking force of the rear wheel Wr reaches the turning point P, hydraulic braking of the front wheel Wf is started from that moment. When the braking force of the rear wheel Wr exceeds a regeneration limit determined from various conditions of the battery 1 and the motor 2, the rear wheel Wr is braked by using both regeneration and oil pressure. When the braking force reaches the turning point Q, the braking force of the rear wheel Wr is weakened by the action of the well-known proportional pressure reducing valve provided inside the modulator 12, and the braking force distribution characteristic as shown by the broken line OPQR is eventually given. Can be
This braking force distribution characteristic OPQR is biased above the ideal distribution characteristic indicated by the broken line, that is, the braking force distribution of the rear wheel Wr exceeds the ideal distribution characteristic, whereby regenerative braking of the rear wheel Wr is performed as much as possible. The battery 1 is charged using the battery to extend the mileage per charge. [ Mode 2 ] This mode is selected when the regenerative braking system is functioning normally and not during the sudden braking, but during steering. This [Mode 2] is also a mode in which the front wheel Wf is braked by hydraulic pressure and the rear wheel Wr is braked by hydraulic pressure and regeneration, as in [Mode 3] described above. However, when the brake pedal 8 is depressed, hydraulic braking of the front wheel Wf is performed concurrently with regenerative braking of the rear wheel Wr. During this time, if the braking force of the rear wheel Wr exceeds the regenerative limit, the rear wheel Wr
Is braked by a combination of regeneration and hydraulic pressure. When the braking force reaches the turning point R, the braking force of the rear wheel Wr is weakened by the proportional pressure reducing valve. As a result, the broken line OQR indicating the braking force distribution characteristic of [Mode 2] is more front wheel than the ideal distribution characteristic indicated by the broken line. The specific force is placed on the braking force of Wf. As described above, by selecting [Mode 2] during steering and simultaneously braking the front wheel Wf and the rear wheel Wr from the time of initial braking, it is possible to avoid a decrease in steering stability. [ Mode 1 ] This mode is selected at the time of sudden braking when the regenerative braking system is not functioning properly or when the regenerative braking system is functioning normally. In this [mode 1], regenerative braking of the rear wheel Wr is not performed, and both the front wheel Wf and the rear wheel Wr are braked by hydraulic pressure.
By performing only the hydraulic braking without performing the regenerative braking of the rear wheel Wr in this manner, a slight delay occurs in the responsiveness while transmitting the rotation of the rear wheel Wr to the motor 2 via the differential 4 and the transmission 3. Responsiveness of the braking force can be improved as compared with regenerative braking. Thus, the braking force distribution characteristic indicated by the polygonal line OQR is such that the braking force of the front wheels Wf is more heavily weighted than the ideal distribution characteristic indicated by the broken line as in the above-mentioned [Mode 2]. As described above, by selecting [mode 1] during sudden braking, braking responsiveness is improved.

At the time of sudden braking during braking in the above [Mode 3], a change from [Mode 3] to [Mode 1] is performed. On the other hand, when the steering operation is performed during the braking in [Mode 3] or when the tendency to lock the wheels on the low μ road is detected, [Mode 3]
From [Mode 2] to [Mode 2]
If a stronger tendency to lock the wheels due to the low μ road is detected during braking by [mode 2], the mode is changed from [mode 2] to [mode 1].
Changes to are made. Thus, by selecting [Mode 2] or [Mode 1] according to the road surface μ, it is possible to avoid a decrease in steering stability. The change from [Mode 3] to [Mode 2] or [Mode 1] is performed along an equal braking force line, that is, a line where the sum of the braking force of the front wheel Wf and the braking force of the rear wheel Wr is kept constant. Done,
This prevents a sudden change in the total braking force of the front and rear wheels Wf, Wr.

Next, the operation of the braking device having the above-described configuration will be described with reference to the flowchart of the main routine shown in FIG.

First, in step S100, various programs and data are stored in the storage devices of the brake ECU 7 and the motor / transmission control ECU 6, and the brake device is initialized to be operable. Subsequent step S20
0, the remaining battery capacity meter 20, the battery temperature sensor 21, the motor speed sensor 22, the wheel speed sensor 23,
Brake pedal depression force sensor 24, accelerator opening degree sensor 2
5. Output signals of the steering sensor 26 and the accumulator pressure sensor 27 are read by the brake ECU 7 (see FIG. 2).

In step S300, the limit value of the regenerative braking force that can be exerted at each moment is calculated based on the output signals of the various sensors. The regenerative braking force limit is determined by the state of the battery 1 and the state of the motor 2, and details thereof will be described later based on the subroutine of step S300.

In step S400, a regenerative braking force equivalent to the engine brake is calculated. In a vehicle using an internal combustion engine as a driving power source, the engine brake is activated when the accelerator pedal is released, but in a vehicle using the motor 2 as a driving power source as in the present embodiment, a system corresponding to the engine brake is used. By applying the power to the rear wheels Wr by regenerative braking, a steering feeling similar to that of a normal vehicle having an internal combustion engine is provided. That is, when the depression force of the accelerator pedal 28 is reduced, the accelerator opening sensor 25
Opening detected by the motor, motor speed sensor 2
A braking force equivalent to an engine brake is calculated based on the motor speed detected by the motor 2 and the wheel speed detected by the wheel speed sensor 23, and the rear wheel Wr connected to the motor 2 regenerates to obtain the braking force. Be braked. The electric power generated by the motor 2 by the regenerative braking is used for charging the battery 1.

In step S500, the distribution ratio between the regenerative braking force and the hydraulic braking force is calculated. That is, [Mode 3], [Mode 2], and [Mode 1] are selected based on the state of the braking operation and steering operation by the driver, the friction coefficient of the road surface, and the like, and from [Mode 3] to [Mode 2]. Alternatively, a mode change to [mode 1] is determined. In each mode, the front wheel Wf
And the magnitude of the regenerative braking force and the hydraulic braking force of the rear wheel Wr are calculated. The specific contents of step S500 will be described later in detail based on the subroutine.

In step S600, a shift position at which the regenerative braking force can be maximized is calculated, and the transmission 3 is automatically operated toward the shift position.
The specific contents of step S600 will be described later based on the subroutine.

In step S700, in order to distribute the regenerative braking force and the hydraulic braking force at a predetermined ratio, the ON / OF of FIG.
The F valves 15f, 15r and the differential pressure valves 16f, 16r are actually controlled. Thus, the electric power generated by the motor 2 by the regenerative braking of the rear wheel Wr is used for charging the battery 1. The specific contents of step S700 will be described later in detail based on the subroutine.

In step S800, anti-lock control is performed to prevent an excessive slip of the front wheel Wf or the rear wheel Wr. That is, when it is detected from the output signal of the wheel speed sensor 23 that the wheels are about to enter the locked state, the ABS control valves 14f and 14r in FIG. 1 are controlled. As a result, the modulator 12 interposed between the master cylinder 9 and the brake cylinders 13f and 13r is operated, and the brake cylinder 13 of the wheel that tends to lock is operated.
The brake hydraulic pressure transmitted to f and 13r is reduced to prevent the wheels from being locked.

In step S900, fail-safe when a failure occurs in the regenerative braking system is achieved. That is, when a failure occurs in the regenerative braking system as shown in the flow of FIG.
f, 15r are held in the valve-open position, and the master cylinder 9 and the modulator 12 communicate directly. As a result, [Mode 1] is unconditionally selected, and the front wheel Wf and the rear wheel Wr are braked by hydraulic pressure as in a normal hydraulic braking system.

Next, the specific contents of step S300 (calculation of the regenerative braking force limit value) in the flowchart of FIG. 4 will be described with reference to FIGS.

As shown in the regenerative braking force limit value calculation routine of FIG. 5, first, at step S301, a limit value T _LMB of the regenerative braking force according to the state of the battery 1 is calculated. A braking force limit value T _LMN is calculated. The limit value T _LMB and the limit value T
The magnitude of _LMN is compared in step S303, and the limit value T _{LM
If B} is larger than the limit value T _LMN , step S3
04 is the smaller limit value T _LMN is the regenerative braking force limit value T _LM
If the limit value T _LMB is equal to or smaller than the limit value T _LMN , the smaller limit value T is determined in step S305.
_LMB is selected as a regenerative braking force limit value T _LM. That is, the regenerative braking force limit value T _LM at that time is determined by smaller one of the limit value T _LMN by the rotational speed limit value T _LMB and motor 2 by the state of the battery 1.

Next, a subroutine of step S301 (calculation of the limit value depending on the battery state) in FIG. 5 will be described with reference to FIG.

When it is detected in step S311 that the brake operation has been performed based on the output signal of the brake pedal depression force sensor 24, the regeneration ON timer RBT starts counting in step S312. Then, step S
At 313, the depth of discharge (DOD) of the battery 1 is calculated based on the output signal of the remaining battery capacity meter 20.

Subsequent steps S314 to S318
In, the limit value T _LMB0 is determined based on the magnitude of the DOD. That is, when the value of DOD is small and the remaining capacity of the battery 1 is large, the limit value T _LMB0 is set to be small. When the value of DOD is large and the remaining capacity of the battery 1 is small, the limit value T _{LMB0 is set.} Is set large. When this Figure 7 will be described in more detail with reference also to (A), when the DOD is relatively remaining capacity of the battery 1 to the threshold value D ₁ or less large, limit value T _LMB0
Is set to a relatively small limit value T _LMB1 . DO
D is a case where the remaining capacity of the battery 1 to the threshold value D ₂ or more is relatively small is set to a limit value T _LMB0 is relatively large limit value T _LMB3. When the DOD is between the threshold value D ₁ and threshold D ₂ is the limit value T
_LMB0 is set to the limit value T _LMB2 between T _LMB1 and T _LMB3 .

[0033] In step S319, the coefficient K ₁ for correcting the limit value T _LMB0 based on the output signal of the battery temperature sensor 21 is determined. That is, the battery 1
Of the battery temperature sensor 21, the output signal TEMP of the battery temperature sensor 21 increases as shown in FIG.
There accompanied to exceed TEMP _0, the temperature coefficient K ₁ is determined so as to increase from 1 linearly.

Subsequent steps S320 to S324
Then, the regeneration O counted by the regeneration ON timer RBT
Coefficient K ₂ for correcting the limit value T _LMB0 based on the magnitude of the N time t is determined. Figure 7 (C) As is clear with reference also to, the charging time coefficient K ₂ is 1 when the regenerative ON time t is the threshold t ₁ following the elapsed time from the regenerative braking is started Is set. Regeneration ON time t
If There becomes a threshold t ₁ or more, the charging time coefficient K ₂ is set to a smaller K ₂₂ than 1, further when the regenerative ON time t becomes a threshold value t ₂ or more, the charging time coefficient K ₂ is the It is set to a smaller K ₂₁ than K _22. In this way, the maximum charge of the battery 1 is efficiently charging time coefficient K ₂ to the initial charging to be performed value of 1, the charging time coefficient K ₂ with the passage of the regenerative ON time t 1 from K _21, K ₂₂
To decrease.

In step S325, the final regenerative braking force limit value T _LMB that depends on the battery 1 is _{changed from} the temperature coefficient K ₁ and the charging time coefficient K _L
It is calculated by multiplying by _two .

The calculation of the regenerative braking force limit value T _LMB is performed every time the brake pedal 8 is depressed.
Is released, the regenerative O is released in step S326.
The N timer is reset.

FIG. 8 shows step S in the flowchart of FIG.
Which corresponds to 302, shows the change in the limit value T _LMN of the regenerative braking force by the output signal N _M of the motor rotation speed sensor 22. As is apparent from the figure, the limit value T _LMN linearly increased with the increase in the rotation speed N _M of the motor 1.
Eventually, it becomes almost constant and then decreases rapidly.

Next, the specific contents of step S500 (regenerative / hydraulic distribution calculation) in the flowchart of FIG.
This will be described with reference to FIGS.

As shown in the regenerative / oil pressure distribution determination routine of FIGS. 9 and 10, first, when a braking operation is performed in step S501, the mode 1 flag is "0" and [mode 1] is set in step S502. Is not selected, and the regenerative braking system has not failed in step S503, and it is not a time of sudden braking in steps S504 and S505, and the road μ is sufficiently large in steps S506 and S507 to lock the wheels. As a result, the time differential value ΔV _W of the wheel speed calculated from the output signal of the wheel speed sensor 23 (the drop in the wheel speed per unit time) is a predetermined threshold value g ₁ , g ₂ (g ₁ > g).
₂ ) The following conditions are satisfied, and both the provisional mode 2 flag M2FL 'and the mode 2 flag M2FL are "0" in step S508 and step S509 and [mode 2] is not selected, and step S510 and step S5
When the steering flag STRFL is not set to “1” in the non-steering operation in step S11, the process proceeds to step S512.
To select [Mode 3]. Then, the step S
If the mode 1 flag is set to “1” in 502, “mode 1” is selected in step S513,
If the mode 2 flag M2FL is set to "1" in step S509, "mode 2" is selected in step S514.

A mode 1 file for determining the selection of [mode 1]
The lag M1FL satisfies one of the following conditions.
Is set to "1" in step S515. In step S503, the regenerative braking system fails.
If. In steps S504 and S505, the
When it is determined that the brake is applied. In step S506, the time differential value ΔV of the wheel speed is obtained._W
Is the larger threshold g ₁If exceeded. (G₁Is
When the braking force distribution of the normal hydraulic braking system approaches lock
(Selected as an estimated value). In step S507, the time differential value ΔV of the wheel speed is selected._W
Is the larger threshold g ₁And the smaller threshold g_Twoof
If between (g_TwoIs the braking force distribution of the normal hydraulic braking device
Select as a value estimated to be unlocked if returned to
), And in step S516, the mode 2
When the lug is set to M1FL "1".

A temporary mode for determining the selection of [Mode 2]
The mode 2 flag M2FL 'is set when the following condition is satisfied.
Is set to "1" in step S522, and
C2 flag M2FL satisfies the following conditions.
Is set to "1" in step S517. In step S507, the time differential value of the wheel speed ΔV_W
Is the smaller threshold g _TwoOver and steps
In step S516, the mode 2 flag is set to "1" for M2FL.
Is not performed (that is, [Mode 3] is selected)
State), and step S518 and step S51
9 if the M2 delay timer M2T is counting down
Go. In steps S518 and S519, the M2 dera
The timer M2T is counting down (that is, M2FL '=
In step 1507, the time differential value ΔV of the wheel speed is set to 1)._W
Is the smaller threshold g_TwoIf the following, or M
When a predetermined time has elapsed by the 2 delay timer M2T
Go. It should be noted that a predetermined time elapses by the M2 delay timer M2T.
Even after a short time, ΔV in step S507_W> G_TwoAnd judgment
[Mode 1] is selected according to the above conditions
Is done. In steps S510 and S511,
When it is determined that tearing is in progress.

When it is determined in step S501 that the brake operation is not being performed, that is, when the depression force on the brake pedal 8 is released, the mode 2 flag M2FL and the mode 1 flag M1FL are both set to "0" in steps S523 and S524 for the first time. Is set to Therefore,
[Mode 2] or [Mode 1] once during one braking
Is selected, there is no reverse transition from [mode 2] or [mode 1] to [mode 3] during the braking.

Next, the details of step S504 (sudden brake determination) in FIG. 9 will be described with reference to the flowchart in FIG. When the brake pedal depression force sensor 24 depression force F _B which is detected by is equal to or greater than the predetermined threshold value in step S531, it is determined that the abrupt brake unconditionally, the sudden braking flag is "1" in step S532 Set.

Meanwhile, the depression force F _B is less than a predetermined threshold value, and when the sudden braking determination timer PTM in step S533 is in the initial value t ₀ at the count start and depression force F _B at that time in step S534 The initial pedaling force is F _B1 . In a succeeding step S535, a sudden brake determination timer P is set.
If TM has not been counted down to 0, the countdown is performed in step S536,
In step S537, the sudden brake flag is set to "0".

In step S535, the sudden braking determination
When Ima PTM is counted down to 0,
Fixed time t₀Has elapsed, at step S538
Pedaling force F_BIs t₀Rear treading force t_B2And step S53
At 9, the sudden braking judgment timer PTM is t₀Reset to
You. Then, in the subsequent step S540, t₀Rear treading force t _B2
 Initial pedaling force F_B1Is the pedal force change threshold ΔF_BCompared with
The difference is the pedaling force change threshold ΔF_BIf it exceeds
In step S532, the sudden brake flag is set to "1".
If it does not exceed, sudden break in step S537
The key flag is set to "0".

[0046] Thus, when if the depression force F _B exceeds the first threshold value and that the amount of increase in pedal force F _B within a predetermined time period exceeds the second threshold value is the sudden braking Is determined.

Next, the details of step S510 (steer condition determination) in FIG. 10 will be described with reference to the flowchart of FIG.
This will be described with reference to the graph of FIG. The vehicle speed V calculated from the output signal of the wheel speed sensor 23 is the largest threshold value V ₃
When larger than the steering flag STRFL is set to "1" when the steering angle detected by the steering sensor 26 theta is greater than the smallest threshold theta _1, a steering flag S when the threshold theta ₁ below
TRFL is set to "0" (step S541, step S541).
S542, S543, S544, S545, S546).

When the vehicle speed V is between the maximum threshold value V ₃ and the lower threshold value V ₂ , the steering flag STRFL is set to “1” when the steering angle θ is larger than the intermediate threshold value θ _2. Is set to the threshold value θ
When it is less than or equal to ₂ , the steering flag STRFL is set to "0" (steps S541, S542, S54).
3, S547, SS545, and S546).

[0049] When the vehicle speed V is between the smallest threshold value V ₁ and the threshold value V ₂ is the steering flag STRF when the steering angle theta is larger than the largest threshold theta ₃
L is set to "1", the steering angle theta steering flag STRFL when the threshold theta ₃ or less is set to "0" (step S541, S542, S548, S54
5, S546).

[0050] When the vehicle speed V is the smallest threshold V ₁ or less, steering flag ST regardless of the size of the steering angle θ
RFL is set to “0” (steps S541 and S541).
546).

As described above, when the vehicle speed V is high, it is determined that the steering is being performed even if the steering angle θ is small, and when the vehicle speed V is low, it is determined that the steering is not being performed unless the steering angle θ is large. Will not be dropped.

Next, details of step S512 (mode 3 distribution determination) of FIG. 10 will be described with reference to the flowchart of FIG. 14 and the graph of FIG. In step S551, the converted regenerative braking force limit value T _RGLM converted into tire torque is calculated by multiplying the regenerative braking force limit value T _LM obtained in step S300 of FIG. 4 by the gear ratio R (n) of the nth speed. Is done. In the following step S552, based on the graph of FIG. 17A, the pedaling force F corresponding to the break point P (the point at which the hydraulic braking of the front wheel Wf is started in [mode 3]) in the braking force distribution characteristic of FIG. _B0 is searched.

[0053] At step S553, reduced regenerative braking force T _RG corresponding to the depression force F _B on the basis of the graph shown in FIG. 17 (B)
Is searched. In the following step S554, the Fr offset amount, that is, the operation amount of the linear solenoid 19f in FIG. 1 is calculated by multiplying the _turning point force _FB0 by a constant. In step S555, the Rr offset amount, that is, the operation amount of the linear solenoid 19r in FIG. 1 is searched based on the graph in FIG. Thus, in step S556, the Fr offset flag and the Rr offset flag for controlling the ON / OFF valves 15f and 15r in FIG. 1 are both set to "1" (valve closed).

Next, the details of step S514 (decision of mode 2 distribution) in FIG. 10 will be described with reference to the flowchart in FIG. 15 and the graph in FIG. In step S561, the converted regenerative braking force limit value T _RGLM converted to tire torque is calculated by multiplying the regenerative braking force limit value T _LM obtained in step S300 of FIG. 4 by the gear ratio R (n) of the nth speed. You. In the following step S562, FIG.
The converted regenerative braking force T _RG is retrieved based on the graph of FIG.

In step S563, the Fr offset amount is set to zero. This is because the braking force distribution characteristic of [Mode 2] in FIG. 1 does not have the break point P, and hydraulic braking of the front wheel Wf is performed from the time of initial braking. Subsequent step S
In 564, the Rr offset amount, that is, the operation amount of the linear solenoid 19r in FIG. 1 is searched based on the graph in FIG. Thus, in step S565, the Fr offset flag for controlling the front wheel ON / OFF valve 15f in FIG. 1 is set to “0” (valve open), and the rear wheel O
The Fr offset flag for closing the N / OFF valve 15r is set to "1" (valve closed).

Next, the details of step S513 (decision of mode 1 distribution) in FIG. 10 will be described with reference to the flowchart in FIG. In this [mode 1], no regenerative braking is performed, and therefore, in step S571, the converted regenerative braking force T _RG
Is set to 0. In subsequent steps S572 and S573, both the Fr offset amount and the Rr offset amount are set to 0. Finally, in step S574, the Fr offset flag and the Fr offset flag are both "0" (valve opened).
And the hydraulic pressure generated by the master cylinder 9 is transmitted to the modulator 12 as it is, and the front wheel Wf and the rear wheel Wr are braked by normal hydraulic pressure.

Next, the details of step S600 (shift command) in FIG. 4 will be described in detail in the flowcharts of FIGS.
1 and the time chart of FIG.

[0058] If it is during the shift in the flow chart of step S601 of FIG. 18 to FIG. 20, the shift flag SHFL is set to "1" at step S602, followed by step S603 reduced regenerative braking force T _RG is 0
, And both the Fr offset flag and the Rr offset flag are set to “0” (valve opening) in step S604. As a result, the front wheel Wf and the rear wheel Wr are braked by normal hydraulic pressure without performing regenerative braking during the shift.

If the shift flag SHFL is set to "1" in step S605 even though the shift is not in progress in step S601, it is determined that the shift has been completed, and in step S606, the front wheel Wf and the rear wheel Wr are determined. Is released, and at step S6
At 07, the shift flag SHFL is set to "0".

If the steering is being performed and the steering flag STRFL is set to "1" in step S608, a shift command described later is not issued.

In the following steps S609 to S613, the current
Regenerative energy E at the current shift position n_(n)Is calculated
Is done. That is, in step S609, the converted regenerative braking force
T_RGThe gear ratio R_(n)By dividing by n speed
Motor torque T_{MT (n)}Is calculated. And
In step S612, based on the graph of FIG.
Luc T_{MT (n)}And the rotation speed N of the motor 2_MFrom motor efficiency η
_(n)Is obtained, and in step S613, the motor effect is obtained.
Rate η_(n)Motor torque T_{MT (n)}And the rotation speed N of the motor 2
_MIs multiplied by the number of times at the shift position n.
Renewable energy E _(n)Is calculated.

Next, in steps S614 to S622, the regenerative energy E _(n-1) when the downshift is performed from the current shift position is calculated. That is, if the current shift position n is the first speed in step S614,
Since downshifting is substantially impossible, step S
The regenerative energy E _(n
-1) is set to 0. On the other hand, if the current shift position n is any of the second to fourth speeds in step S614, n-1 is determined in steps S616 to S622 as described above.
The regenerative energy E _(n-1) when downshifting to a high speed is calculated. At that time, when the motor torque T _{MT (n-1)} exceeds the regenerative braking force limit value T _LM in step S617, the regenerative braking force limit value T _LM motor torque T _MT at step S618 _{(n- 1)} . In the case of a downshift, the motor 2 at the time of downshift is determined in step S619.
The rotational speed N _{M (n-1)} is, gear ratio R _(n), is computed from R rpm N _M in _(n-1) and n speed _(n), the rotational speed N _{M (n} in the results step S620 _{If -1)} is over-rev, the regenerative energy E _(n-1) is set to 0 in step S615.

Next, in steps S623 to S630, the regenerative energy E _{(n + 1)} when the shift is shifted up from the current shift position is calculated. That is, if the current shift position n is the fourth speed in step S623,
Since it is practically impossible to upshift, step S
The regenerative energy E _(n
+1) is set to 0. Subsequent steps S625 to S63
At 0, the regenerative energy E _{(n + 1)} when shifting up is calculated as described above. At that time, step S6
At 26, the motor torque T _{MT (n + 1)} becomes the regenerative braking force limit value T _LM
In step S627, the regenerative braking force limit value _TLM is set to the motor torque _{TMT (n + 1)} in step S627. still,
In the case of the upshift, the overrev does not occur, so that the determination of the overrev performed in the downshift is not performed.

In steps S631 to S633, the current regenerative energy E _(n) , the regenerative energy E _(n-1) when downshifting, and the regenerative energy E _{(n + 1)} when upshifting are performed. The three are compared, and if E _(n-1) becomes maximum, a downshift command is issued in step S634. Conversely, if E _{(n + 1)} becomes maximum, an upshift command is issued in step S635. Is issued.

The above shift operation will be described with reference to the time chart of FIG. For example, it is assumed that the brake pedal 8 is operated so that the pedaling force gradually increases at times T ₁ , T ₃ , and T ₈ , and a regenerative braking command is issued at time T ₂ .
If it is determined to shift down shift position so as to maximize the time regenerative energy, for example, 3 speed to the second speed, the clutch is released at time T _4.

When the clutch is released, the rear wheel Wr and the motor 2 are disconnected and the regenerative braking force is disabled, so that the time T ₄
Regenerative braking command of the motor 2 to T ₇ is canceled from. And while from between That time T ₄ the regenerative braking is not performed until T ₇ is the hydraulic brake command is issued hydraulic brake is replaced by regenerative braking. And Thus, at time T ₅ in the disengagement period of the clutch from time T ₄ to T _6, a shift command is issued downshifting from the third speed to the second speed is executed.

As described above, the total braking force
T_Two~ T_FourThen, due to regenerative braking, time T_Four~ T₇Then oil
The time T₇~ T₉Then, by regenerative braking,
Time T ₉After that, it is secured by using both regenerative braking and hydraulic braking.
You.

Next, the details of step S700 (regenerative / hydraulic braking force control) in FIG. 4 will be described with reference to the flowchart in FIG.

First, in step S701, the converted regenerative braking force T _RG is output. And as is clear from FIG.
In [Mode 3] and [Mode 2], the rear wheel Wr is regeneratively braked so as to obtain the converted regenerative braking force T _RG at the time of initial braking, and the electric power generated by the motor 2 by this regenerative braking is used to charge the battery 1. Provided. Step S702
And S703, steps S554 and S555 in FIG. 14 corresponding to [Mode 3], steps S563 and S564 in FIG. 15 corresponding to [Mode 2], and steps S572 and S573 in FIG. 17 corresponding to [Mode 1]. The determined Fr offset amount and Rr offset amount are output. As a result, the linear solenoids 19f, 1 of the hydraulic control valves of the front wheel Wf and the rear wheel Wr shown in FIG.
9r operates, and the set load of the springs 17f and 17r of the differential pressure valves 16f and 16r is adjusted to a predetermined magnitude.

If the Fr offset flag is not set to "1" in the following step S704 ([mode 2]
And [mode 1]), at step S705
The N / OFF valve 15f is kept open, and if it is set to "1" (in the case of [Mode 3]),
In step S706, the ON / OFF valve 15f is operated to close.

Accordingly, in [Mode 2] and [Mode 1] in which the ON / OFF valve 15f is kept open, the brake oil pressure generated by the master cylinder 9 is directly transmitted to the modulator 12 and the [Mode] in FIG. As shown in the braking force distribution characteristics of [2] and [Mode 1], the front wheel Wf is hydraulically braked from the time of initial braking.

On the other hand, in [Mode 3], since the ON / OFF valve 15f is closed, the brake oil pressure generated by the master cylinder 9 is blocked by the ON / OFF valve 15f and passes through the differential pressure valve 16f. Modulator 1
2, the differential pressure valve 16f is not opened until the depression force of the brake pedal 8 increases to a predetermined value due to the set load of the spring 17f. As a result, as shown by the line OP in the braking force distribution characteristic of [Mode 3] in FIG. 1, the application of the hydraulic braking force to the front wheel Wf during the initial braking is prevented. Then, when the brake hydraulic pressure generated by the master cylinder 9 reaches a magnitude corresponding to the break point P,
The differential pressure valve 16f opens, and the hydraulic braking force starts to act on the front wheel Wf.

Returning to the flowchart of FIG. 23, if the Rr offset flag is not set to "1" in step S707 (in the case of [mode 1]), step S70
8, the ON / OFF valve 15r is kept open, and if it is set to "1" (in the case of [Mode 3] and [Mode 2]), the ON / OFF valve 15r is turned ON / OFF in Step S709.
The F valve 15r is closed.

Accordingly, in the [mode 1] in which the ON / OFF valve 15r is kept open, the brake oil pressure generated by the master cylinder 9 is directly transmitted to the modulator 12, and the [mode 1] in FIG. ], The rear wheel Wr is hydraulically braked from the time of initial braking.

On the other hand, in [Mode 3] and [Mode 2], the ON / OFF valve 15r is closed, so that the brake oil pressure generated by the master cylinder 9 increases the ON / O pressure.
The differential pressure valve 16r is blocked by the FF valve 15r and transmitted to the modulator 12 via the differential pressure valve 16r, so that the differential pressure valve 16r does not open until the depression force of the brake pedal 8 increases to a predetermined value due to the set load of the spring 17r. .
As a result, the hydraulic braking force is prevented from acting on the rear wheel Wr to the regenerative limit in the braking force distribution characteristics of [Mode 3] and [Mode 2] in FIG. When the brake oil pressure generated by the master cylinder 9 reaches a value corresponding to the regenerative limit, the differential pressure valve 16r is opened and a hydraulic braking force starts to act on the rear wheel Wr. The braking force and the hydraulic braking force act.

FIG. 24 shows another embodiment in which the regeneration / oil pressure distribution determination routine shown in FIGS. 9 and 10 is simplified.

In this embodiment, when the regenerative braking system is not out of order, the vehicle is not steering, the pedal effort is not more than the threshold value, and the road surface μ is not low, the normal [mode 3] is set. Selected (steps S581, S5
82, S583, S584, S585, S586, S5
87).

If the regenerative braking system has failed in step S581, [mode 1] is unconditionally selected in step S589. Step S5
82, if it is determined in S583 that steering is being performed, if the pedaling force is equal to or greater than the threshold value in step S584 and it is determined that rapid braking is being performed, or if step S584 is determined.
If it is determined in 585 and S586 that the road μ is low and there is a possibility of wheel lock, [mode 2] is selected in step S588.

FIG. 25 is a flowchart showing step S582 in FIG.
This shows a subroutine of (steering condition determination). When the lateral acceleration of the vehicle is equal to or more than the reference value in step S591, it is determined that the vehicle is being steered and step S5 is performed.
At 92, the steering flag STRFL is set to "1", and when it is smaller than the reference value, it is determined that the steering is not being performed, and the steering flag STR is determined at step S593.
FL is set to "0". Incidentally, the step S59
In step 1, it is also possible to determine the steering condition by using the yaw rate r of the vehicle as a parameter instead of the lateral acceleration of the vehicle.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various small design changes can be made.

For example, in the embodiment, the vehicle in which the front wheel Wf is the driven wheel and the rear wheel Wr is the driving wheel is illustrated. However, the present invention relates to a vehicle in which the front wheel Wf is the driving wheel and the rear wheel Wr is the driven wheel. It is also applicable.

[0082]

As described above, according to the first aspect of the present invention, the friction coefficient of the road surface is large, and the wheel slides during braking .
When the lip amount (ie, lock tendency) is small, the regenerative priority mode can be selected to enhance the energy recovery effect by regenerative braking, and when the road surface friction coefficient is small and the wheel slip amount (ie, lock tendency) is large. By selecting the normal mode that follows the ideal distribution characteristics,
It is possible to stabilize the behavior of the vehicle by preventing the wheels from being locked.

According to a second feature of the present invention, the slip
When the flop amount exceeds a relatively large first threshold value, it is possible to improve the damping response by selecting the normal allocation mode only hydraulic brake and said slip amount is relatively small second Works When the threshold value is exceeded, the normal distribution mode that uses both regenerative braking and hydraulic braking can be selected to achieve both an energy recovery effect and a braking response.

Further, according to the third feature of the present invention, the slip amount is reduced by the second amount even though the normal distribution mode in which both the regenerative braking and the hydraulic braking are used is selected to reduce the braking force distribution of the driving wheels. When the condition exceeding the threshold value has passed for a predetermined time,
It is possible to increase the braking responsiveness said regenerative braking switching et Re to the normal mode from the normal mode does not perform regenerative braking performing Runode, the driving wheels when the friction coefficient of the road surface is small state continued braked only by the hydraulic pressure .

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electric vehicle including a braking device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a schematic explanatory diagram of a braking mode.

FIG. 4 is a flowchart of a main routine.

FIG. 5 is a flowchart of a subroutine corresponding to step S300 of the main routine.

FIG. 6 is a flowchart of a subroutine corresponding to step S301 in FIG.

FIG. 7 is a graph accompanying the flowchart of FIG. 6;

FIG. 8 is a graph accompanying the flowchart of FIG. 5;

FIG. 9 is a flowchart of a subroutine corresponding to step S500 of the main routine.

FIG. 10 is a flowchart of a subroutine corresponding to step S500 of the main routine.

FIG. 11 is a flowchart corresponding to a subroutine of step S504 in FIG. 9;

FIG. 12 is a flowchart corresponding to a subroutine of step S510 in FIG. 10;

FIG. 13 is a graph accompanying the flowchart of FIG. 12;

FIG. 14 is a flowchart corresponding to a subroutine of step S512 in FIG. 10;

FIG. 15 is a flowchart corresponding to a subroutine of step S514 in FIG. 10;

FIG. 16 is a flowchart corresponding to a subroutine of step S513 in FIG. 10;

FIG. 17 is a graph accompanying the flowcharts of FIGS. 14 and 15;

FIG. 18 is a flowchart corresponding to a subroutine of step S600 of the main routine.

FIG. 19 is a flowchart corresponding to a subroutine of step S600 of the main routine.

FIG. 20 is a flowchart corresponding to a subroutine of step S600 of the main routine.

FIG. 21 is a graph accompanying the flowcharts of FIGS. 18 to 20;

FIG. 22 is a time chart when a shift change is performed during braking.

FIG. 23 is a flowchart of a subroutine corresponding to step S700 of the main routine.

FIG. 24 is a flowchart of another embodiment corresponding to FIGS. 9 and 10;

FIG. 25 is a flowchart corresponding to a subroutine of step S582 in FIG. 24;

[Explanation of symbols]

Reference Signs List 1 battery 2 motor 5 PDU (control means) 6 motor / mission control ECU (control means) 7 brake ECU (control means) 8 brake pedal (brake operator) g1 _first threshold value g2 _second threshold Value Wf Front wheel (driven wheel) Wr Rear wheel (drive wheel)

Continuation of front page (72) Inventor Atsuo Ohno 1-4-1 Chuo, Wako-shi, Saitama Prefecture Honda Technical Research Institute Co., Ltd. (56) References JP-A-49-31021 (JP, A) JP-A-59-230856 (JP, A) JP-A-3-270602 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 7/24 B60T 8/28 B60T 8/34 B60L 15/00-15 / 28

Claims (3)

(57) [Claims] The brake operator is connected to and driven by a driven wheel (Wf) that can be hydraulically braked by operating a brake operator (8) and a motor (2) that uses a battery (1) as an energy source. The drive wheel (Wr) capable of hydraulic braking and regenerative braking by the operation (8) and the driven wheel (Wf)
And control for controlling the switching from regenerative priority mode that exceed the regenerative braking force of the drive wheels (Wr) to the normal mode along said ideal distribution characteristic with respect to the ideal distribution characteristic of the braking force of the drive wheels (Wr) Means for controlling the switching from the regeneration priority mode to the normal mode by the control means (5, 6, 7). A braking device for an electric vehicle, wherein the braking is performed when a slip amount of a wheel (Wr) exceeds a predetermined threshold value. Wherein said slip amount is a first threshold (g ₁₎ the normal mode is selected when exceeded run by only the hydraulic braking and the slip amount is the first
Characterized by the execution by the threshold (g ₁₎ the combination of the normal mode regenerative braking and the hydraulic braking is selected when exceeding the small second threshold (g ₂₎ than, claim 2. The braking device for an electric vehicle according to claim 1. 3. When a predetermined time has elapsed after the slip amount exceeds the second threshold value (g ₂ ), a normal mode in which both regenerative braking and hydraulic braking are used is switched to a normal mode in which only hydraulic braking is performed. The braking device for an electric vehicle according to claim 2, wherein the switching is performed.