JPH05161213A - Brake system for motor vehicle - Google Patents

Abstract

PURPOSE:To efficiently recover energy in a motor vehicle comprising drive wheels subjected to hydraulic brake and regenerative brake and driven wheels subjected to hydraulic brake by applying regenerative brake preferentially when a brake pedal is stepped strongly whereas applying combined brake or only hydraulic brake when the brake pedal is stepped weakly. CONSTITUTION:A brake control ECU 7 receives data from an r.p.m. sensor 22, front and rear wheel speed sensors 23, a brake pedal stepping force sensor 24, an accelerator opening sensor 28, a steering sensor 26, an accumulator pressure sensor 27, and the like. The ECU 7 controls a motor 2 through a motor transmission control ECU 6 and a power drive unit PDU 5. When the ECU 7 makes a decision that the brake pedal is stepped strongly based on various input data. regenerative brake is selected and a battery 1 is charged with power generated from the motor 2. On the contrary, when a decision is made that the brake pedal is stepped weakly, regenerative brake and hydraulic brake are combined or only hydraulic brake is selected. According to the invention, energy can be recovered effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driven wheel which can be hydraulically braked by the operation of a brake operator, and is driven by being connected to a motor which uses a battery as an energy source and which is operated by the brake operator. Switching between the regenerative braking priority mode in which the regenerative braking capable of regenerative braking and the ideal distribution characteristic of the braking force of the driven wheel and the driven wheel exceed the regenerative braking force of the driving wheel to the normal mode in accordance with the ideal distribution characteristic. The present invention relates to a braking device for an electric vehicle including control means for controlling the braking device.

[0002]

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

[0003]

In such an electric vehicle, in order to maximize the energy recovery efficiency by regenerative braking, the regenerative braking priority mode is usually used in which the regenerative braking force of the driving wheels is made higher than the ideal distribution characteristic of the braking force. It is conceivable that the braking is performed in accordance with the above, and if necessary, the braking is performed in the normal mode in accordance with the ideal distribution characteristic.

It is an object of the present invention to appropriately perform the mode switching control according to the operating force of the brake operator in the above-described vehicle braking device capable of switching the braking mode.

[0005]

In order to achieve the above object, the present invention is connected to and driven by a driven wheel hydraulically braked by the operation of a brake operator and a motor using a battery as an energy source. The drive wheel capable of hydraulic braking and regenerative braking by the operation of the brake operator, and the ideal regenerative braking mode in which the regenerative braking force of the drive wheel exceeds the ideal distribution characteristic of the braking force of the driven wheel and the driven wheel. A braking device for an electric vehicle, comprising: a control unit that controls switching to a normal mode in accordance with distribution characteristics,
A first feature is that the control unit switches the regeneration priority mode to the normal mode when the operating force of the brake operator exceeds a predetermined threshold value.

Further, according to the present invention, the driven wheel which can be hydraulically braked by the operation of the brake operator and the motor which is connected to a motor which uses a battery as an energy source are driven and hydraulic braking and regenerative braking can be performed by the operation of the brake operator. Control for controlling switching from a regenerative braking priority mode in which the regenerative braking force of the drive wheel is exceeded to a normal mode in accordance with the ideal distribution characteristic, to the ideal distribution characteristic of the driving wheels and the braking forces of the driven wheels and the driving wheels. A braking device for an electric vehicle comprising: means for switching from a regeneration priority mode to a normal mode by the control means when an increase rate of the operating force of the brake operator exceeds a predetermined threshold value. Second thing
It is a feature of.

[0007]

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

1 to 23 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of an electric vehicle equipped with the braking device, FIG. 2 is a block diagram of a control system, and FIG. 3 is a braking mode. FIG. 4 to FIG. 23 are a flow chart, 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.
In a four-wheeled vehicle provided with r, a rear wheel Wr is connected to an electric motor 2 that uses a battery 1 as an energy source via a transmission 3 and a differential 4 in four forward stages. 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 the electric power generated by the motor 2 in association with regenerative braking. Control. The PDU
5 and transmission 3 are motor / mission 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.

The master cylinder 9 operated by the brake pedal 8 is connected to an accumulator 11 that accumulates pressure by a hydraulic pump 10 via a modulator 12 and a brake cylinder 13f for each front wheel Wf and a brake cylinder 13r for each rear wheel Wr. Connected to. Modulator 12
Has a two-channel ABS (antilock 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, The brake hydraulic pressure transmitted to the brake cylinders 13f and 13r is reduced.

A brake cylinder 13f for the front wheel Wf is provided in an oil passage connecting the master cylinder 9 and the modulator 12.
A hydraulic control valve including an ON / OFF valve 15f for controlling the brake hydraulic pressure transmitted to the vehicle and a differential pressure valve 16f is different from the 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 the pressure valve 16r is provided.

The front wheel ON / OFF valve 15f is a solenoid-operated normally open on-off valve, 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 has a valve element 18 biased in a 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 wheels
The F valve 15r and the differential pressure valve 16r have the same structure as that for the front wheels. A one-way valve that restricts hydraulic pressure transmission from the master cylinder 9 to the modulator 12 and allows hydraulic pressure transmission from the modulator 12 to the master cylinder 9 is interposed in the bypass oil passage.

As can be seen by referring also to FIG.
The brake ECU 7 includes a battery remaining capacity meter 20 and a battery temperature sensor 21 provided in the battery 1, a motor rotation speed sensor 22 that detects the rotation speed of the motor 2, and wheel speeds provided to 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 an accumulator 12. The hydraulic pump 10 connected to the accumulator pressure sensor 27 and controlled based on the output signals thereof, the hydraulic control valve including the ON / OFF valves 15f and 15r and the differential pressure valves 16f and 16r, and 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 by receiving a regenerative braking command and a mission shift command from the brake ECU 7. ..

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

Front wheels W in a vehicle equipped with this 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 according to the change in the driving state. [ Mode 3 ] This mode is selected in a normal operating state. That is, it is selected when the regenerative braking system is functioning normally, and neither during the hard braking nor during the steering. [Mode 3] is a mode in which the front wheel Wf is hydraulically braked and the rear wheel Wr is braked hydraulically and regeneratively. When the brake pedal 8 is depressed, only the rear wheel Wr is first regeneratively braked and the front wheel Wf is hydraulically braked. Not done
When the braking force of the rear wheel Wr reaches the break point P, hydraulic braking of the front wheel Wf is started from that moment. When the braking force of the rear wheel Wr exceeds the regenerative limit determined by various conditions of the battery 1 and the motor 2, the rear wheel Wr is braked by the combined use of regenerative and hydraulic 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 finally, the braking force distribution characteristic as shown by the polygonal line OPQR is given. Be done.
This braking force distribution characteristic OPQR is biased above the ideal distribution characteristic shown by the broken line, that is, the braking force distribution of the rear wheels Wr is biased to exceed the ideal distribution characteristic, whereby regenerative braking of the rear wheels Wr is possible. The battery 1 is used to charge the battery 1 to extend the travelable distance per charge. [ Mode 2 ] This mode is selected when the regenerative braking system is functioning normally and not during the hard braking but during the steering. Similar to [Mode 3] described above, 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. However, when the brake pedal 8 is depressed, hydraulic braking of the front wheels Wf is performed concurrently with regenerative braking of the rear wheels Wr, and if the braking force of the rear wheels Wr exceeds the regenerative limit during that time, the rear wheels Wr
Is braked by the combined use 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, and as a result, the polygonal line OQR showing the braking force distribution characteristic of [Mode 2] is closer to the front wheel than the ideal distribution characteristic shown by the broken line. The weight is given to the braking force of Wf. In this way, by selecting [Mode 2] during steering and simultaneously braking the front wheels Wf and the rear wheels Wr from the time of initial braking, it is possible to avoid deterioration of steering stability. [ Mode 1 ] This mode is selected at the time of sudden braking when the regenerative braking system does not function normally or when the regenerative braking system functions normally. In this [mode 1], regenerative braking of the rear wheels Wr is not performed, and both the front wheels Wf and the rear wheels Wr are hydraulically braked.
By performing only the hydraulic braking without performing the regenerative braking of the rear wheels Wr in this way, a slight delay occurs in responsiveness while transmitting the rotation of the rear wheels Wr to the motor 2 via the differential 4 and the transmission 3. The response of the braking force can be enhanced as compared with regenerative braking. Thus, the braking force distribution characteristic indicated by the polygonal line OQR has a greater weight on the braking force of the front wheel Wf than the ideal distribution characteristic indicated by the broken line as in the above [Mode 2]. By selecting [Mode 1] during the sudden braking as described above, the braking response can be improved.

At the time of sudden braking during braking in the above [Mode 3], the change from [Mode 3] to [Mode 1] is performed. On the other hand, if the steering operation is performed during braking in [Mode 3], or if the tendency to lock the wheels on the low μ road is detected, [Mode 3]
From [Mode 2] to [Mode 2]
If a stronger wheel locking tendency due to a low μ road is detected during braking by, the [mode 2] to [mode 1]
Changes to. In this way, by selecting [Mode 2] or [Mode 1] depending on the road surface μ, it is possible to avoid deterioration of steering stability. The change from [Mode 3] to [Mode 2] or [Mode 1] is along an equal braking force line, that is, a line where the sum of the braking force of the front wheels Wf and the braking force of the rear wheels Wr is kept constant. Done by
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 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 / mission control ECU 6, and the braking device is initially set in an operable state. Continuing step S20
At 0, the battery remaining capacity meter 20, the battery temperature sensor 21, the motor rotation speed sensor 22, the wheel speed sensor 23,
Brake pedal depression force sensor 24, accelerator opening sensor 2
5, the output signals of the steering sensor 26 and the accumulator pressure sensor 27 are read into 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. This 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 engine braking is calculated. In a vehicle that uses an internal combustion engine as a driving power source, the engine brake operates when the depression force of the accelerator pedal is released, but in a vehicle that uses the motor 2 as a driving power source as in the present embodiment, the control equivalent to the engine brake is performed. By applying 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 pedal effort of the accelerator pedal 28 is weakened, the accelerator opening sensor 25
Accelerator opening detected by the motor and motor speed sensor 2
The braking force equivalent to the engine brake is calculated based on the motor rotation speed detected by 2 and the wheel speed detected by the wheel speed sensor 23, and the rear wheel Wr connected to the motor 2 is regenerated to obtain the braking force. Is braked. Then, 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, the [Mode 3], [Mode 2], and [Mode 1] are selected based on the state of the braking operation and the steering operation by the driver, the friction coefficient of the road surface, and the like, and the [Mode 3] to [Mode 2] are selected. Alternatively, the mode change to [mode 1] is decided. And in each mode, the front wheel Wf
And the magnitudes of the regenerative braking force and the hydraulic braking force of the rear wheel Wr are calculated. The specific content of step S500 will be described later 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 content 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, ON / OF of FIG.
The F valves 15f and 15r and the differential pressure valves 16f and 16r are actually controlled. Thus, the electric power generated by the motor 2 by the regenerative braking of the rear wheel Wr is used to charge the battery 1. The specific content of step S700 will be described later based on the subroutine.

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

In step S900, fail-safe is ensured when a failure occurs in the regenerative braking system. That is, as shown in the flow chart of FIG. 3, when a failure occurs in the regenerative braking system, the normally open ON / OFF valve 15
The master cylinder 9 and the modulator 12 directly communicate with each other by holding f and 15r in the valve open position. As a result, [Mode 1] is unconditionally selected, and the front wheels Wf and the rear wheels Wr are hydraulically braked as in a normal hydraulic braking system.

Next, the specific contents of step S300 (calculation of the regenerative braking force limit value) in the above-mentioned 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, in step S301, the limit value T _LMB of the regenerative braking force depending on the state of the battery 1 is calculated, and in step S302, the regenerative braking force limit value T _LMB is regenerated. The braking force limit value T _LMN is calculated. The limit value T _LMB and the limit value T
The size of _LMN is compared in step S303 to determine the limit value T _{LM.
If B} is larger than the limit value T _LMN , step S3
04, the smaller limit value T _LMN is the regenerative braking force limit value T _LM
And the limit value T _LMB is less than or equal to the limit value T _LMN , the smaller limit value T is determined in step S305.
_LMB is selected as the regenerative braking force limit value T _LM . That is, the regenerative braking force limit value T _LM at that time is determined by the smaller one of the limit value T _LMB depending on the state of the battery 1 and the limit value T _LMN depending on the rotation speed of the motor 2.

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

When it is detected in step S311 that the brake operation is performed by 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 battery remaining capacity meter 20.

Subsequent Steps S314 to S318
Then, the limit value T _LMB0 is determined based on the size 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 small, and 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 . Also, DO
When D is equal to or greater than the threshold value D _{2 and} the remaining capacity of the battery 1 is relatively small, the limit value T _LMB0 is set to a relatively large limit value T _LMB3 . When the DOD is between the threshold value D ₁ and the threshold value D ₂ , the limit value T
_LMB0 is set to the limit value T _LMB2 between the T _LMB1 and T _LMB3 .

In the following step S319, the coefficient K ₁ for correcting the limit value T _LMB0 is determined based on the output signal of the battery temperature sensor 21. That is, the battery 1
Since the capacity of the battery temperature sensor 21 increases as the temperature rises, the output signal TEMP of the battery temperature sensor 21 as shown in FIG.
The temperature coefficient K ₁ is determined to increase linearly from _{1 as} the temperature exceeds TEMP ₀ .

Subsequent steps S320 to S324
Then, the regeneration O counted by the regeneration ON timer RBT
The coefficient K ₂ for correcting the limit value T _LMB0 is determined based on the magnitude of the N time t. As is clear from also referring to FIG. 7C, when the regeneration ON time t, which is the elapsed time after the regenerative braking is started, is equal to or less than the threshold value t ₁ , the charging time coefficient K ₂ becomes 1. Is set. Regeneration ON time t
Is greater than or equal to the threshold t ₁ , the charging time coefficient K ₂ is set to K ₂₂ smaller than 1, and when the regeneration ON time t is greater than or equal to the threshold t ₂ , the charging time coefficient K ₂ is It is set to K ₂₁ , which is smaller than K ₂₂ . In this way, the charging time coefficient K ₂ becomes the maximum value 1 at the initial stage of charging when the battery 1 is efficiently charged, and the charging time coefficient K ₂ is from 1 to K ₂₁ , as the regeneration ON time t elapses. K ₂₂
Decrease to.

Then, in step S325, the final regenerative braking force limit value T _LMB depending on the battery 1 becomes the limit value T _LMB0 by the DOD, the temperature coefficient K ₁ and the charging time coefficient K.
It is calculated by multiplying by ₂ .

The regenerative braking force limit value T _LMB is calculated each time the brake pedal 8 is stepped on.
When the pedaling force of is released, the regeneration O is performed in step S326.
The N timer is reset.

FIG. 8 is a step S of the flowchart of FIG.
This corresponds to 302 and shows a change in the limit value T _LMN of the regenerative braking force due to 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 of 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 (regeneration / hydraulic pressure distribution calculation) of the above-mentioned flowchart of FIG.
This will be described with reference to FIGS. 9 to 17.

As shown in the regeneration / hydraulic pressure distribution determination routines of FIGS. 9 and 10, when the braking operation is first performed in step S501, the mode 1 flag is "0" and [mode 1] is set in step S502. Not selected, the regenerative braking system has not failed in step S503, and there is no sudden braking in steps S504 and S505, and the road surface μ is sufficiently large in steps S506 and S507 to lock the wheels. There is no tendency, and as a result, the time differential value ΔV _W (falling of wheel speed per unit time) of the wheel speed calculated from the output signal of the wheel speed sensor 23 is a predetermined threshold value g ₁ , g ₂ (g ₁ > g
₂ ) or less, and both the temporary 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 11 and the steering is not performed, step S512 is performed.
[Mode 3] is selected with. Then, the step S
When 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.

The mode 1 flag that determines the selection of [mode 1]
For the lag M1FL, one of the following conditions is satisfied:
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 to be a brake. In step S506, the time differential value ΔV of the wheel speed_W
The larger the threshold g ₁If it exceeds. (G₁Through
Even if the braking force distribution of the usual hydraulic braking device approaches the lock
It is selected as an estimated value) In step S507, the time differential value ΔV of the wheel speed_W
The larger the threshold g ₁And the smaller threshold g₂of
If it is between (g₂Is the braking force distribution of a normal hydraulic braking system
Select as a value estimated that the lock will be released by returning to
Mode), and in step S516
If the lag is M2FL is set to "1".

In addition, a temporary mode for determining the selection of [Mode 2].
Mode 2 flag M2FL 'is set when the following conditions are met.
Is set to "1" in step S522, and
Do 2 flag M2FL satisfies the following conditions or
Is set to "1" in step S517. In step S507, the time differential value ΔV of the wheel speed_W
The smaller threshold g ₂And step
In S516, the mode 2 flag is set to M2FL to "1".
Not done (ie [mode 3] is selected
State), and step S518 and step S51
If the M2 delay timer M2T is counting down at 9,
Go. In steps S518 and S519, the M2 delay
Imma M2T is counting down (that is, M2FL '=
1) In step S507, the time differential value ΔV of the wheel speed_W
The smaller threshold g₂When it becomes below, or M
When the predetermined time by the 2-delay timer M2T has elapsed
Go. It should be noted that the M2 delay timer M2T has passed a predetermined time.
Even after the error, ΔV is calculated in step S507._W> G₂Judgment
If turned off, [Mode 1] is selected according to the above conditions
To be done. In steps S510 and S511,
When it is determined that the tearing is in progress.

When it is determined in step S501 that the brake is not being operated, that is, when the depression force of the brake pedal 8 is released, the mode 2 flag M2FL and the mode 1 flag M1FL are both set to "0" for the first time in steps S523 and S524. 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, details of step S504 (judgment of sudden braking) in FIG. 9 will be described with reference to the flowchart in FIG. If the pedal effort F _B detected by the brake pedal pedal force sensor 24 is equal to or greater than a predetermined threshold value in step S531, it is unconditionally determined to be a sudden brake, and the rapid brake flag is set to “1” in step S532. Is set.

On the other hand, when the pedaling force F _B is less than the predetermined threshold value and the sudden braking determination timer PTM is at the initial value t ₀ at the start of counting in step S533, the pedaling force F _B at that time is determined in step S534. Initial pedal force F _B1 . In the following step S535, the sudden braking determination timer P
When TM is not counted down to 0, the countdown is performed in step S536, and
In step S537, the sudden braking flag is set to "0".

In step S535, the sudden braking judgment
When Imma PTM is counted down to 0
Fixed time t₀Is passed, then at step S538
Pedaling force F_BIs t₀Rear tread force t_B2And step S53
In 9 the sudden braking judgment timer PTM is t₀Is reset to
It Then, in subsequent step S540, t₀Rear tread force t _B2
 Initial pedaling force F_B1Difference is the pedal effort change threshold ΔF_BCompared to
And the difference is the pedal effort change threshold ΔF._BAbove
The sudden braking flag is set to "1" in step S532.
If it is not over, sudden break in step S537
The flag is set to "0".

As described above, when the pedaling force F _B exceeds the first threshold value and when the increase amount of the pedaling force F _B within the predetermined time exceeds the second threshold value, the braking is sudden. Is determined.

Next, the details of step S510 (steering condition determination) of FIG. 10 will be described with reference to the flowchart of FIG. 12 and FIG.
This will be described with reference to the graph of No. 3. The vehicle speed V calculated from the output signal of the wheel speed sensor 23 is the maximum 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,
S542, S543, S544, S545, S546).

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

When the vehicle speed V is between the threshold value V ₂ and the smallest threshold value V ₁ , the steering flag STRF is set when the steering angle θ is larger than the largest threshold value θ _3.
When L is set to "1" and the steering angle θ is equal to or smaller than the threshold value θ ₃ , the steering flag STRFL is set to "0" (steps S541, S542, S548, S54).
5, S546).

When the vehicle speed V is equal to or smaller than the minimum threshold value V ₁ , the steering flag ST is set regardless of the steering angle θ.
RFL is set to "0" (steps S541, S
546).

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

Details of step S512 (mode 3 distribution determination) of FIG. 10 will be described below with reference to the flowchart of FIG. 14 and the graph of FIG. In step S551, the regenerative braking force limit value T _LMLM calculated in 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. To be done. In the following step S552, the pedaling force F corresponding to the break point P (the point where the hydraulic braking of the front wheels Wf is started in [Mode 3]) in the braking force distribution characteristic of FIG. 1 based on the graph of FIG. 17 (A). _B0 is searched.

In step S553, the converted regenerative braking force T _RG corresponding to the pedal effort F _B is calculated based on the graph of FIG. 17B.
Will be searched. In a succeeding step S554, the Fr offset amount, that is, the operation amount of the linear solenoid 19f in FIG. 1 is calculated by multiplying the _breaking pedal force F _B0 by a constant. In step S555, the Rr offset amount, that is, the operation amount of the linear solenoid 19r of FIG. 1 is searched based on the graph of FIG. Then, in step S556, both the Fr offset flag and the Rr offset flag for controlling the ON / OFF valves 15f and 15r of FIG. 1 are set to "1" (closed valve).

Details of step S514 (mode 2 distribution determination) of FIG. 10 will be described below with reference to the flowchart of FIG. 15 and the graph of FIG. In step S561, 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. It In the following step S562, in FIG.
The converted regenerative braking force T _RG is searched based on the graph of 7 (D).

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

Details of step S513 (determination of mode 1 distribution) in FIG. 10 will be described below with reference to the flowchart in FIG. Since regenerative braking is not performed in this [mode 1], the converted regenerative braking force T _RG is calculated in step S571.
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, both the Fr offset flag and the Fr offset flag are "0" (open valve).
The hydraulic pressure generated by the master cylinder 9 is directly transmitted to the modulator 12, and the front wheels Wf and the rear wheels Wr are braked by the normal hydraulic pressure.

Next, the details of step S600 (shift command) in FIG. 4 will be described with reference to the flowcharts in FIGS.
A description will be given based on the graph of No. 1 and the time chart of FIG.

If the shift is in progress in step S601 of the flowcharts of FIGS. 18 to 20, the shift flag SHFL is set to "1" in step S602, and then the converted regenerative braking force T _RG is set to 0 in step S603.
And the Fr offset flag and the Rr offset flag are both set to "0" (valve open) in step S604. As a result, the front wheel Wf and the rear wheel Wr are braked by the 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 is completed, and in the following step S606, the front wheel Wf and the rear wheel Wr are determined. The hydraulic braking of step S6 is released, and step S6 is performed.
At 07, the shift flag SHFL is set to "0".

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

At subsequent steps S609 to S613, the current
Regenerative energy E at current shift position n_(n)Is calculated
To be done. That is, in step S609, the converted regenerative braking force is
T_RGGear ratio R_(n)By dividing by
Drive motor torque T_{MT (n)}Is calculated. And the
At step S612, the motor control is performed based on the graph of FIG.
Luk T_{MT (n)}And the rotation speed N of the motor 2_MTo motor efficiency η
_(n)Is calculated, and in step S613, the motor effect
Rate η_(n)Motor torque T_{MT (n)}And the rotation speed N of the motor 2
_MBy multiplying by
Raw energy E _(n)Is calculated.

Next, in steps S614 to S622, the regenerative energy E _(n-1) when downshifting from the current shift position is calculated. That is, when the current shift position n is the first speed in step S614,
Since downshifting is virtually impossible, step S
Regenerative energy E _(n
-1) is set to 0. On the other hand, if the current shift position n is any one of the 2nd speed to the 4th speed in step S614, n-1 as in the above in steps S616 to S622.
The regenerative energy E _(n-1) in the case of downshifting at high speed is calculated. At that time, if 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 is changed to the motor torque T _{MT (n- in} step S618. ₁₎ In the case of downshifting, the motor 2 at the time of downshifting 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 overrev, 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 shifting up from the current shift position is calculated. That is, when the current shift position n is the fourth speed in step S623,
Since upshifting is practically impossible, step S
Regenerative energy E _(n
+1) is set to 0. Subsequent steps S625 to S63
At 0, the regenerative energy E _{(n + 1)} in the case of upshifting is calculated as described above. At that time, step S6
At 26, the motor torque T _{MT (n + 1)} is equal to the regenerative braking force limit value T _LM.
If it exceeds, the regenerative braking force limit value T _LM is set to the motor torque T _{MT (n + 1)} in step S627. still,
In the case of the shift up, no overrev occurs, so the determination of the overrev performed in the case of the shift down is not performed.

Thus, in steps S631 to S633, the current regenerative energy E _(n) , regenerative energy E _(n-1) when downshifting, and regenerative energy E _{(n + 1)} when upshifting When the three are compared and E _(n-1) is the maximum, a shift down command is issued in step S634, and conversely, when E _{(n + 1)} is the maximum, a shift up command is issued in step S635. Is emitted.

The above shift operation will be described with reference to the time chart of FIG. For example, it is assumed that the pedaling force of the brake pedal 8 is operated so as to gradually increase at times T ₁ , T ₃ , and T ₈ , and a regenerative braking command is issued at time T ₂ .
At this time, when it is determined to shift down the shift position from, for example, the third speed to the second speed in order to maximize the regenerative energy, 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 becomes impossible. Therefore, at time T ₄
The regenerative braking command of the motor 2 is canceled from T ₇ to T ₇ . Then, while regenerative braking is not performed, that is, from time T ₄ to T ₇ , a hydraulic brake command is issued and hydraulic braking is replaced with 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 is
T₂~ T_FourThen, due to regenerative braking, time T_Four~ T₇Then oil
Time T due to pressure braking₇~ T₉With regenerative braking,
Tick T ₉After that, it is secured by using both regenerative braking and hydraulic braking.
It

Details of step S700 (regeneration / hydraulic braking force control) in FIG. 4 will be described below 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 that the converted regenerative braking force T _RG is obtained 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. Be served. Step S702
And S703, in steps S554 and S555 of FIG. 14 corresponding to [mode 3], steps S563 and S564 of FIG. 15 corresponding to [mode 2], and steps S572 and S573 of 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 for the front wheels Wf and the rear wheels 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 in the case of [mode 1]), in step S705
If the N / OFF valve 15f is kept open and is set to "1" (in the case of [mode 3]),
In step S706, the ON / OFF valve 15f is closed.

Therefore, in [mode 2] and [mode 1] in which the ON / OFF valve 15f is kept open, the brake hydraulic pressure generated by the master cylinder 9 is directly transmitted to the modulator 12, and the [mode] in FIG. 2] and [mode 1], the front wheels Wf are hydraulically braked from the initial braking time, as shown in the braking force distribution characteristics.

On the other hand, since the ON / OFF valve 15f is closed in [mode 3], the brake hydraulic pressure generated by the master cylinder 9 is blocked by the ON / OFF valve 15f and passed through the differential pressure valve 16f. Modulator 1
2, the differential pressure valve 16f does not open until the pedaling 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 segment OP in the braking force distribution characteristic of [mode 3] in FIG. 1, the hydraulic braking force is prevented from acting on the front wheels Wf during the initial braking. 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 wheels 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.
If the ON / OFF valve 15r is kept open in step 8 and is set to "1" (in the case of [mode 3] and [mode 2]), it is turned on / off in step S709.
The F valve 15r is closed.

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

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

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

In this embodiment, when the regenerative braking system has not failed, the steering is not being performed, the pedaling force is not more than the threshold value, and the road surface μ is not low, the normal [mode 3] is set. Selected (steps S581 and S5)
82, S583, S584, S585, S586, S5
87).

When the regenerative braking system is out of order in step S581, [mode 1] is unconditionally selected in step S589. Also, step S5
82, S583, when it is determined that the steering is being performed, when it is determined that the pedaling force is equal to or more than the threshold value and the braking is suddenly performed in step S584, or step S584.
When it is determined in 585 and S586 that the road surface μ is low and the wheels may be locked, [Mode 2] is selected in step S588.

FIG. 25 shows step S582 of FIG.
This shows a subroutine of (steering condition determination). When the lateral acceleration of the vehicle is equal to or larger than the reference value in step S591, it is determined that the vehicle is in the stepping state and step S5 is executed.
In step 92, the steering flag STRFL is set to "1", and when it is less than the reference value, it is determined that the steering is not being performed, and in step S593, the steering flag STR is set.
FL is set to "0". Incidentally, the step S59
In 1, it is possible to determine the steering condition 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 has been illustrated, but the present invention is applied to the vehicle in which the front wheel Wf is the driving wheel and the rear wheel Wr is the driven wheel. However, it is applicable.

[0081]

As described above, according to the first feature of the present invention, it is possible to enhance the energy recovery effect by regenerative braking by selecting the regenerative priority mode during normal braking in which the operating force of the brake operator is small. By selecting the normal mode that follows the ideal distribution characteristic when the braking force of the brake operator exceeds the threshold value, it is possible to enhance the braking response and stabilize the behavior of the vehicle.

According to the second aspect of the present invention, the regenerative priority mode can be selected during normal braking in which the operating force of the brake operator is small to increase the energy recovery effect by regenerative braking. By selecting the normal mode in accordance with the ideal distribution characteristic at the time of sudden braking in which the increase rate of the operating force of the brake operator exceeds the threshold value, it becomes possible not only to finely detect the sudden braking condition, but also the braking response. It is possible to improve the vehicle stability and stabilize the behavior of the vehicle.

[Brief description of 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.

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

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

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

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.

11 is a flowchart corresponding to the subroutine of step S504 of FIG.

FIG. 12 is a flowchart corresponding to the subroutine of step S510 of FIG.

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

FIG. 14 is a flowchart corresponding to the subroutine of step S512 of FIG.

FIG. 15 is a flowchart corresponding to the subroutine of step S514 of FIG.

16 is a flowchart corresponding to the subroutine of step S513 of FIG.

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

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

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

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

FIG. 21 is a graph associated with the flowcharts of FIGS.

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.

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 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) Wf Front wheel (driven wheel) Wr Rear wheel (driving wheel)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Oba 1-4-1, Chuo, Wako, Saitama Stock Company Honda R & D Co., Ltd.

Claims (2)

[Claims] 1. The brake operating element is connected to and driven by a driven wheel (Wf) which can be hydraulically braked by operating a brake operating element (8) and a motor (2) whose energy source is a battery (1). Driving wheel (Wr) capable of being hydraulically and regeneratively braked by operation of (8) and driven wheel (Wf)
And control means for controlling switching from the regenerative braking priority mode in which the regenerative braking force of the driving wheel (Wr) is exceeded to the ideal distribution characteristic of the braking force of the driving wheel (Wr) to the normal mode along the ideal distribution characteristic. A braking device for an electric vehicle comprising: (5, 6, 7), wherein switching from a regeneration priority mode to a normal mode by the control means (5, 6, 7) is performed by the brake operator (8).
The braking device for an electric vehicle, characterized in that the braking force is applied when the operating force of the above exceeds a predetermined threshold value. 2. The brake operator (8) 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) whose energy source is a battery (1), and the brake operator. Driving wheel (Wr) and driven wheel (Wf) capable of hydraulic braking and regenerative braking by the operation of (8).
And control means for controlling switching from the regenerative braking priority mode in which the regenerative braking force of the driving wheel (Wr) is exceeded to the ideal distribution characteristic of the braking force of the driving wheel (Wr) to the normal mode along the ideal distribution characteristic. A braking device for an electric vehicle comprising: (5, 6, 7), wherein switching from a regeneration priority mode to a normal mode by the control means (5, 6, 7) is performed by the brake operator (8).
A braking device for an electric vehicle, which is performed when the rate of increase in the operating force exceeds a predetermined threshold value.