JP2000013905A - Braking device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a braking device for an electric motor which utilizes regenerative braking effectively and with which substantially constant pedal stroke can be obtained, regardless of whether or not the regenerative braking is applied together. SOLUTION: This braking device generates a liquid pressure braking which makes up for a regenerative braking, by turning branched pipe line change-over valves B1 to B4 to the communicating position and main pipe line change-over valves C1 to C4 to a shutoff position, when the regenerative braking can be generated. By turning the branched pipe line change-over valves B1 to B4 to the shutoff position and by changing over the main pipe line change-over valves C1 to C4, the liquid pressure of the master cylinder reaches the level corresponding to the limited value of the regenerative braking.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a braking device for an electric vehicle.

[0002]

2. Description of the Related Art For example, according to a braking device for an electric vehicle disclosed in Japanese Patent Application Laid-Open No. 5-176408, a hydraulic cylinder connected to a master cylinder and a wheel cylinder (hydraulic braking device) is approximated to a wheel cylinder. A stroke simulator that consumes the liquid with the specified characteristics is provided. In such a braking device, when braking a drive wheel using regenerative braking force together, the flow path from the master cylinder to the wheel cylinder is within a predetermined range of the master cylinder hydraulic pressure that increases according to the depression of the brake pedal. Shut off and the stroke simulator consumes liquid instead. While the stroke simulator is consuming liquid, the hydraulic braking force is limited, and the regenerative braking force is used instead. In addition, a corresponding pedal stroke is given to the brake pedal by the consumption of the liquid by the stroke simulator. In this way, a sense of incompatibility does not occur in the brake operation during regenerative braking. The braking device is provided with a relief valve in which an upper limit value of the predetermined range of the master cylinder hydraulic pressure is set and an electromagnetic valve for shutting off or communicating the fluid flow, in association with the stroke simulator. .

[0003]

However, in the conventional braking device as described above, even when the braking is performed only by the hydraulic braking force, the stroke simulator on the hydraulic system operates to consume the liquid. . Therefore, the pedal stroke differs between when regenerative braking is used and when only hydraulic braking is used, and the brake feeling is different. Further, when an ABS (anti-lock brake mechanism) is further provided in a braking device having such a stroke simulator, an ABS valve must be provided in addition to the relief valve and the solenoid valve, which complicates the configuration.

[0004] In view of the above-mentioned conventional problems, a first object of the present invention is to obtain a substantially constant pedal stroke irrespective of whether regenerative braking is used together with effective use of regenerative braking force. To provide a braking device for an electric vehicle. A second object of the present invention is to provide a braking device for an electric vehicle having a simple structure even when an ABS is provided, while effectively utilizing the regenerative braking force.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a front wheel and a rear wheel are provided with a hydraulic braking device which is operated by an input hydraulic pressure from a master cylinder, and at least one of the front wheel and the rear wheel is controlled by a brake operation. In an electric vehicle braking device to which a motor capable of generating power is connected, provided between the master cylinder and the hydraulic braking device,
A main line switching valve having a communication position for transmitting the input hydraulic pressure from the master cylinder, and a shutoff position for interrupting the transmission of the input hydraulic pressure; and a line connecting the main line switching valve and the master cylinder. A branch line switching valve connected to the master cylinder via a branch line, and having a communication position for transmitting the input hydraulic pressure from the master cylinder, and a shutoff position for interrupting the transmission of the input hydraulic pressure, A stroke simulator that is connected to the master cylinder via the branch line switching valve and absorbs a fluid amount and a fluid pressure required when the regenerative braking force during regenerative braking is generated as a hydraulic braking force; In the case where a regenerative braking force can be generated, the branch pipeline switching valve is set from the shut-off position to the communication position, the main pipeline switching valve is set to the shut-off position, and the master When the output hydraulic pressure of the cylinder reaches the hydraulic pressure corresponding to the limit value of the regenerative braking force at the time of the brake operation, the branch pipeline switching valve is set to the shut-off position, and the main pipeline switching valve is switched and controlled. And a controller for generating a hydraulic braking force that compensates for the lack of the regenerative braking force.

[0006] In the braking device for an electric vehicle configured as described above, when a regenerative braking force can be generated during a brake operation, the output hydraulic pressure of the master cylinder is set with the main pipeline switching valve in the shut-off position. The transmission to the hydraulic braking device is prevented, and the branch pipeline switching valve is set to the communicating position to allow the stroke simulator to absorb the output hydraulic pressure of the master cylinder. Further, when the output hydraulic pressure of the master cylinder reaches the hydraulic pressure corresponding to the limit value of the regenerative braking force at the time of the brake operation, the branch pipeline switching valve is set to the shut-off position, and the main pipeline switching valve is switched and controlled. In addition, a hydraulic braking force that compensates for the lack of the regenerative braking force is generated.

In the braking device for an electric vehicle (claim 1), the branch line switching valve and the main line switching valve are solenoid valves, which are in a shut-off position and a communication position in a demagnetized state, respectively. (Claim 2). In this case, when only hydraulic braking is performed, the master cylinder and the hydraulic braking device are communicated with each other by the main line switching valve in the demagnetized state, and the master cylinder and the stroke simulator are shut off by the branch line switching valve in the demagnetized state. Therefore, the output hydraulic pressure of the master cylinder can be transmitted to the hydraulic braking device without operating the stroke simulator.

In the braking device for an electric vehicle (claim 1), when the regenerative braking force can be generated, the control unit switches the branch pipeline until the hydraulic pressure of the hydraulic braking device reaches an invalid pressure. The valve may be set to the shutoff position and the main line switching valve may be set to the communication position (claim 3). In this case, the output hydraulic pressure of the master cylinder is supplied to the hydraulic braking device through the main pipeline switching valve until the hydraulic pressure of the hydraulic braking device reaches the invalid pressure.

In the braking device for an electric vehicle (claim 1), when the shortage of the regenerative braking force is compensated by the hydraulic braking force, the main pipeline switching valve may be switched by duty control. Item 4). in this case,
The duty control makes it possible to easily control the output hydraulic pressure supplied from the main pipeline switching valve to the hydraulic braking device.

[0010] In the braking device for an electric vehicle (Claim 1), a communication is provided between the branch pipeline switching valve and the main pipeline switching valve and the master cylinder, and transmits input hydraulic pressure from the master cylinder. A common switching valve having a position and a shut-off position for interrupting the transmission of the input hydraulic pressure.When the regenerative braking force starts to decrease, the hydraulic pressure absorbed by the stroke simulator becomes higher than the hydraulic pressure of the hydraulic braking device. Under the condition of being high, the common switching valve is in the shut-off position, the branch pipeline switching valve is in the communicating position, and the main pipeline switching valve uses the hydraulic pressure absorbed by the stroke simulator to reduce the regenerative braking force. The switching control may be performed so as to generate a supplementary hydraulic braking force (claim 5). In this case, the fluid pressure and fluid volume absorbed by the stroke simulator are:
When the regenerative braking force starts to decrease due to a decrease in vehicle speed or the like, the regenerative braking force is released as a hydraulic braking force that compensates for the decrease.

Further, in the braking device for an electric vehicle (claim 1), the hydraulic braking device and the reservoir tank are provided in a pressure reducing pipe branched from a downstream side of the main pipeline switching valve and connected to the reservoir tank. May be provided. In this case, the main line switching valve acts to supply the hydraulic pressure to the hydraulic braking device as a “fill valve” in the ABS control, and the pressure reducing line switching valve acts as a “relaxation valve” to increase the hydraulic pressure of the hydraulic braking device. It acts to relax. Therefore, by using the main line switching valve provided regardless of the presence or absence of the ABS control, the addition of the pressure-reducing line switching valve alone causes the A
BS function can be provided.

Further, in the braking device for an electric vehicle (claim 5), the hydraulic braking device and the reservoir tank are provided in a pressure reducing pipe branched from a downstream side of the common switching valve and connected to the reservoir tank. A pressure reducing line switching valve that shuts off and communicates may be provided (claim 7). In this case, the main line switching valve and the common switching valve act to supply the hydraulic pressure to the hydraulic braking device as a “fill valve” in the ABS control, and the pressure reducing line switching valve functions as a “relaxation valve” for the hydraulic braking device. It acts to relax the hydraulic pressure. Therefore, the ABS function can be provided only by adding the pressure reducing line switching valve by using the main line switching valve and the common switching valve provided regardless of the presence or absence of the ABS control.

In the braking apparatus for an electric vehicle (claim 7), the pressure reducing line provided with the pressure reducing line switching valve is branched from a line connecting the main line switching valve and the common switching valve. (Claim 8). in this case,
At the time of the ABS control, the common switching valve is used as a “fill valve” while the main pipeline switching valve is kept at the communication position. Therefore, it is possible to reduce the switching frequency of the main pipeline switching valve during the brake operation.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment FIG. 1 is a diagram showing a configuration of a braking device for an electric vehicle according to a first embodiment of the present invention. Connection. In the figure, a master cylinder 2 is connected to a brake pedal 1. Two hydraulic control systems 3A and 3B are connected to the master cylinder 2, and one hydraulic control system 3A is provided with a hydraulic braking device 4RL on the left rear wheel.
And the hydraulic braking device 4FR on the right side of the front wheels. The other hydraulic control system 3B is connected to a hydraulic brake 4RR on the right side of the rear wheel and a hydraulic brake 4FL on the left of the front wheel. That is, the hydraulic pipe is an X pipe. The electric vehicle is a four-wheel drive vehicle in which both front wheels 5F and rear wheels 5R are driven by a motor 6.

The hydraulic control system 3A comprises a pair of main line switching valves C1 and C2 and a pair of branch line switching valves B1 and B.
2. It includes check valves 71 to 73 and a stroke simulator S1. The main line switching valves C1 and C2 are respectively connected to the master cylinder 2 and the hydraulic braking devices 4RL and 4F.
And a communication position for transmitting the input hydraulic pressure from the master cylinder 2 to the corresponding hydraulic braking devices 4RL and 4FR, and a shutoff position for interrupting the transmission of the input hydraulic pressure. Have. Main line switching valve C1 in demagnetized state
And C2 are in the communicating position.

The branch line switching valves B1 and B2 are solenoid valves connected from the line connecting the master cylinder 2 and the main line switching valves C1 and C2 via branch lines 81 and 82, respectively. A communication position for transmitting the input hydraulic pressure from the master cylinder 2 to the stroke simulator S1,
And a blocking position for blocking transmission of the input hydraulic pressure. In the demagnetized state, the branch pipeline switching valves B1 and B2 are in the shut-off position. The check valves 71 and 72 are respectively connected to the main line switching valves C
1 and C2 in parallel to ensure a return path from the hydraulic braking devices 4RL and 4FR to the master cylinder 2. Further, the other check valves 73 include branch line switching valves B1 and B1.
2 are connected in parallel to each other and the stroke simulator S
A return path from 1 to the master cylinder 2 is secured.

On the other hand, the hydraulic control system 3B includes a pair of main line switching valves C3 and C4, and a pair of branch line switching valves B3 and B3.
4. The check valves 74 to 76 and the stroke simulator S2 are provided. The main line switching valves C3 and C4 are respectively connected to the master cylinder 2 and the hydraulic braking devices 4RR and 4F.
And a communication position for transmitting the input hydraulic pressure from the master cylinder 2 to the corresponding hydraulic braking devices 4RR and 4FL, and a shutoff position for interrupting the transmission of the input hydraulic pressure. Have. Main line switching valve C3 in demagnetized state
And C4 are in the communicating position.

The branch line switching valves B3 and B4 are solenoid valves connected from the line connecting the master cylinder 2 and the main line switching valves C3 and C4 via branch lines 83 and 84, respectively. A communication position for transmitting the input hydraulic pressure from the master cylinder 2 to the stroke simulator S2,
And a blocking position for blocking transmission of the input hydraulic pressure. The branch pipeline switching valves B3 and B4 in the demagnetized state are in the shut-off position. The check valves 74 and 75 are respectively connected to the main line switching valve C
3 and C4 in parallel to ensure a return path from the hydraulic braking devices 4RR and 4FL to the master cylinder 2. The other check valve 76 is provided with branch line switching valves B3 and B3.
4 are connected in parallel with each other and the stroke simulator S
2 has a return passage from the master cylinder 2 to the master cylinder 2.

The hydraulic pressure sensor 91 is connected to one of the outputs of the master cylinder 2. Further, the hydraulic sensors 92 and 93 are connected to the pipelines leading to the hydraulic braking devices 4RR and 4FL, respectively. The brake switch 10 is provided near the brake pedal 1 and operates when the brake pedal 1 is depressed. The brake controller 11 includes a main line switching valve C1 to C4, a branch line switching valve B
1 to B4, hydraulic pressure sensors 91 to 93, brake switch 1
0 and the motor controller 12.
The motor controller 12 is a drive circuit of the motor 6 and is supplied with power from a battery 13. Motor 6
Is driven at an arbitrary speed in accordance with a drive current supplied from the motor controller 12, and applies regenerative braking force to the front wheels 5F and the rear wheels 5R during regenerative braking.

Next, the braking control operation of the braking device for an electric vehicle according to the first embodiment configured as described above will be described with reference to the flowcharts of FIGS. It is the brake controller 11 that performs the processing shown in this flowchart, and the routine shown in the flowchart is repeatedly executed. The notation "B" in the flowchart means the branch pipeline switching valves B1 to B4. "C" means the main pipeline switching valves C1 to C4.

When the process is started, the brake controller 11 determines whether or not the brake switch 10 is on (Step 501). Here, when the brake operation is not performed, the brake switch 10 is off, so that the regenerative braking off state is maintained (step 51).
2), branch line switching valves B1 to B4 and main line switching valve C1
〜C4 is kept off (step 517). As a result, the branch line switching valves B1 to B4 are in the shut-off position, and the main line switching valves C1 to C4 are in the communicating position. Therefore, the master cylinder 2 is in communication with the hydraulic braking devices 4RL, 4RR, 4FL, and 4FR, and is in a state of waiting for a brake operation.

Next, when the brake is operated, that is, when the brake pedal 1 is depressed, the brake switch 10 is turned on, and the process proceeds from step 501 to step 502. In step 502, the brake controller 11
Fetches from the motor controller 12 information on the maximum regenerative braking force RBmax available at that time. The regenerative braking force changes depending on the vehicle speed, the discharge state of the battery 13, the temperature, and the like, and cannot be used when any failure occurs in the regenerative braking system. Then, when this RBmax is 0 (Y in step 503), the brake controller 11 turns off the regenerative braking (step 512), sets the branch pipeline switching valves B1 to B4 to the shut-off position, and sets the main pipeline switching valve. C1 to C4 are maintained at the communication positions, respectively. Therefore, when the regenerative braking force cannot be used, the entire braking force is borne by the hydraulic braking force. At this time, the stroke simulators S1 and S2 do not consume the liquid.

If the maximum regenerative braking force RBmax is not 0 (N in step 503), the brake controller 11 takes in the value of the master cylinder hydraulic pressure Pm from the hydraulic pressure sensor 91, and sets the wheel cylinder hydraulic pressure in the hydraulic braking devices 4RR and 4FL. The value of the pressure Pw is determined by the hydraulic pressure sensors 92 and 9
3 (step 504). Subsequently, the brake controller 11 compares the hydraulic pressure P _RBmax for obtaining the hydraulic braking force corresponding to the maximum regenerative braking force RBmax with the master cylinder hydraulic pressure Pm (Step 505). If it has not reached _RBmax , a value obtained by multiplying the master cylinder hydraulic pressure Pm by a predetermined coefficient α is output to the motor controller 12 as the regenerative braking force command value RB (step 513). The motor controller 12 receives this and performs regenerative braking by the motor 6.

Next, in step 514, the brake controller 11 compares the master cylinder pressure Pm, the invalid pressure P _0. Here, the invalid pressure P ₀ refers to a hydraulic pressure required to reduce the invalid strokes of the hydraulic braking devices 4RL, 4RR, 4FL, and 4FR. If the master cylinder pressure Pm is invalid pressure P ₀ or less, the brake controller 11 proceeds to step 517, branch line switching valve B
1 to B4 are maintained in the shut-off position, and the main pipeline switching valves C1 to C4
Is maintained in the communication position. Therefore, the master cylinder hydraulic pressure P
m is directly supplied to the hydraulic braking devices 4RL, 4RR, 4FL, and 4FR, and the ineffective stroke is reduced.

[0025] When the master cylinder pressure Pm exceeds the invalid pressure _{P 0,} the brake controller 11 step 516
To branch line switching valves B1 to B4 and main line switching valve C
1 to C4 are turned on. As a result, the branch line switching valves B1 to B4 are in the communication position, and the main line switching valves C1 to C
Numeral 4 indicates a blocking position. Therefore, the wheel cylinder hydraulic pressure P
w is held in that state, and the stroke simulators S1 and S2 absorb the hydraulic pressure and liquid amount from the master cylinder 2 instead. Due to this absorption, the amount of fluid that would be consumed if the braking force corresponding to the regenerative braking force was generated only by the hydraulic braking force is consumed, and the brake pedal 1 is given a corresponding pedal stroke. Therefore, there is no difference in pedal stroke between the case where the regenerative braking force is used and the case where only the hydraulic braking force is used, so that the brake feeling does not feel uncomfortable.

Returning to step 505, if the master cylinder hydraulic pressure Pm is _{equal to} or higher than the hydraulic pressure P _RBmax (that is, if the regenerative braking force alone is not enough), the brake controller 1
1 indicates that the regenerative braking force command value RB is equal to the maximum regenerative braking force RBmax.
The regenerative braking force command value RB is output (step 506). The motor controller 12 receives this and performs regenerative braking by the motor 6.

Subsequently, at step 507, the brake controller 11 sets the master cylinder hydraulic pressure Pm to (Pw
−P ₀ ) + P _{RB It} is determined whether or not it is larger than _RB . here,
P _RB is a hydraulic pressure for obtaining a hydraulic braking force equivalent to RB, and (Pw−P ₀ ) is a hydraulic pressure actually contributing to the generation of the hydraulic braking force. That is, in step 507, the master cylinder hydraulic pressure Pm corresponding to the required braking force is
It is determined whether the braking force is greater than the total braking force currently output (= hydraulic braking force + regenerative braking force). Here, if the master cylinder pressure Pm is greater than _{(Pw-P 0) + P} RB, the brake controller 11 proceeds to step 515, if it is not larger, or "less", the brake controller 11 proceeds to step 508.

[0028] In step 508, the brake controller 11, the master cylinder hydraulic pressure Pm _(Pw-P 0)
+ Determines whether equal P _RB. If they are equal, the process proceeds to step 509, where the brake controller 11 turns off the branch pipeline switching valves B1 to B4 and sets the main pipeline switching valve C1.
To C4 are turned on. Thereby, the branch pipeline switching valve B1
To B4 and the main pipeline switching valves C1 to C4 are both in the shutoff position. Therefore, the current wheel cylinder hydraulic pressure Pw is maintained. Master cylinder pressure Pm is _{(Pw-P 0) + P} RB
Is not equal to the master cylinder hydraulic pressure Pm
Is smaller than (Pw−P ₀ ) + P _RB , P _RB = Pm
−Pw (step 510), and a predetermined coefficient α is assigned to P _RB.
Is output as the regenerative braking force command value RB multiplied by (step 511). Thus, the regenerative braking force is adjusted (suppressed).

On the other hand, in step 515, the brake controller 11 turns off the branch line switching valves B1 to B4, and switches the main line switching valves C1 to C4 by a pulse train drive signal to output a duty. Control. Thereby, the branch pipeline switching valves B1 to B4
Is in the shutoff position, and the main line switching valves C1 to C4 increase the output hydraulic pressure (wheel cylinder hydraulic pressure Pw) while repeating communication and shutoff. With such duty control, the hydraulic braking force can be freely controlled.

When the brake pedal 1 is returned, the brake switch 10 is turned off.
And 517 are executed to return to the state before the brake operation was performed. Further, since the master cylinder hydraulic pressure Pm becomes a negative pressure, the liquid sent to the hydraulic braking devices 4RL, 4RR, 4FL, and 4FR respectively receives the main line switching valve C1, the check valve 71, and the main line switching valve C3. Then, the air is returned to the master cylinder 2 through the check valve 74, the main line switching valve C4 and the check valve 75, and the main line switching valve C2 and the check valve 72. The liquid absorbed by the stroke simulators S1 and S2 is returned to the master cylinder 2 through the check valves 73 and 76, respectively.

FIG. 9 is a graph showing changes of the master cylinder hydraulic pressure Pm, the regenerative braking force, the wheel cylinder hydraulic pressure Pw, and the pedal stroke with respect to the time t based on the above operation. In the graph of the pedal stroke, the solid line indicates the characteristic during braking using regenerative braking, and the broken line indicates the characteristic during braking using only hydraulic braking without using regenerative braking. The "B" and "C" columns in the table below the pedal stroke indicate the operating states corresponding to the graphs of the branch pipeline switching valves B1 to B4 and the main pipeline switching valves C1 to C4, respectively. . The “D” column relates to a second embodiment described later, and is not related to the present embodiment.

In FIG. 9, the operation from time 0 to t1 corresponds to the operation of executing the step 517 and ending in the flowchart of FIG. The operation from time t1 to t2 corresponds to the operation of executing step 516 and terminating. The operation from time t2 to t3 corresponds to the operation of executing step 515 and ending. The operation from time t3 to t4 corresponds to the operation of executing step 509 and terminating. The operation from time t4 to t5 corresponds to the operation of executing step 515 and ending. The operation after time t5 corresponds to the operation of executing step 517 and terminating. As shown in the graph of the pedal stroke, the pedal stroke is similar between the case where only the hydraulic braking is performed (dashed line) and the case where the regenerative braking is used together (solid line). It can be carried out.

<< Second Embodiment >> FIG. 2 shows a second embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an electric vehicle braking device according to an embodiment of the present invention, which has a configuration in which an ABS is additionally provided to the electric vehicle braking device according to the first embodiment. In the figure, a hydraulic control system 3A includes a pair of main line switching valves C1 and C2, a pair of branch line switching valves B1 and B2, a pair of pressure reducing line switching valves D1 and D2, and a check valve 71.
73, 77, a pump 14, a stroke simulator S1, and a reservoir tank R1.

The main pipeline switching valves C1 and C2 are solenoid valves provided between the master cylinder 2 and the hydraulic braking devices 4RL and 4FR, respectively.
It has a communication position for transmitting input hydraulic pressure from master cylinder 2 to L and 4FR, and a shutoff position for interrupting transmission of input hydraulic pressure. The branch pipeline switching valves B1 and B2 are solenoid valves connected from the pipeline connecting the master cylinder 2 and the main pipeline switching valves C1 and C2 via branch pipelines 81 and 82, respectively. It has a communicating position for transmitting the input hydraulic pressure from the second to the stroke simulator S1, and a shutoff position for interrupting the transmission of the input hydraulic pressure.

The check valves 71 and 72 are connected in parallel to the main line switching valves C1 and C2, respectively, and are connected to the hydraulic braking device 4R.
The return passage from L and 4FR to the master cylinder 2 is secured. The other check valve 73 is a branch line switching valve B1.
And B2 in parallel with each other to secure a return path from the stroke simulator S1 to the master cylinder 2. The pressure-reducing pipeline switching valves D1 and D2 are solenoid valves provided between the reservoir tank R1 and the check valves 71 and 72, respectively, and are connected to the master cylinder 2 and the reservoir tank via the main pipeline switching valves C1 and C2, respectively. There is a communication position for communicating R1 with each other, and a blocking position for blocking R1. The check valve 77 and the pump 14 are connected in series with each other in the same liquid flow direction, and are provided between the master cylinder 2 and the reservoir tank R1, and the liquid from the reservoir tank R1 to the master cylinder 2 is provided. Forcible return.

On the other hand, the hydraulic control system 3B includes a pair of main line switching valves C3 and C4 and a pair of branch line switching valves B3 and B3.
4, a pair of pressure reducing line switching valves D3 and D4, a check valve 74 to
76 and 78, pump 15, stroke simulator S
2 and a reservoir tank R2. In addition,
The pump 15 is driven by a motor 16 together with the pump 14 described above.

The main line switching valves C3 and C4 are solenoid valves provided between the master cylinder 2 and the hydraulic braking devices 4RR and 4FL, respectively.
It has a communication position for transmitting input hydraulic pressure from master cylinder 2 to R and 4FL, and a shutoff position for interrupting transmission of input hydraulic pressure. The branch pipeline switching valves B3 and B4 are solenoid valves connected from the pipeline connecting the master cylinder 2 and the main pipeline switching valves C3 and C4 via branch pipelines 83 and 84, respectively. 2 has a communication position for transmitting the input hydraulic pressure from the second to the stroke simulator S2, and a shutoff position for interrupting the transmission of the input hydraulic pressure.

The check valves 74 and 75 are connected in parallel to the main line switching valves C3 and C4, respectively, and are connected to the hydraulic braking device 4R.
A return path from R and 4FL to the master cylinder 2 is secured. The other check valve 76 is a branch line switching valve B3.
And B4 in parallel with each other to secure a return path from the stroke simulator S2 to the master cylinder 2. The depressurizing line switching valves D3 and D4 are solenoid valves provided between the reservoir tank R2 and the check valves 74 and 75, respectively, and are connected to the master cylinder 2 and the reservoir tank via the main line switching valves C3 and C4, respectively. It has a communication position for communicating R2 with each other, and a blocking position for blocking this. The check valve 78 and the pump 15 are connected in series with each other in the same flow direction, and are provided between the master cylinder 2 and the reservoir tank R2. Forcible return. On the other hand, for the ABS control, the front wheels 5F
Speed sensors 16F and 16R are provided for both the rear wheels 5R and the rear wheels 5R, respectively, and these are connected to the brake controller 11. The other configuration is the same as that of the first embodiment, and the description is omitted.

Next, a braking control operation of the braking device for an electric vehicle according to the second embodiment configured as described above will be described with reference to flowcharts of FIGS. The notation "B" in the flowchart means the branch pipeline switching valves B1 to B4. "C" means the main pipeline switching valves C1 to C4. “D” means the pressure reducing line switching valves D1 to D4. This flowchart is
The differences from the flowchart (FIG. 5) in the first embodiment are the steps 5A1, 5A2 and 5A3 relating to the ABS control described below, and the contents of steps 509 and 515 to 517 relating to the output. The other steps are the same, and the description is omitted here.

When the brake switch 10 is turned on from off, the brake controller 11 proceeds from step 501 to step 5A1, and determines whether the ABS flag is on or off. Here, the ABS flag refers to the speed sensor 16R.
And a flag that is turned on when the wheel lock state during the braking operation is detected based on the speed signals of the second and fourth speeds.
In step 501 immediately after the start of the braking operation, the normal A
The BS flag is off, and the process proceeds to step 50.
Proceed to 2 and later. Then, steps 509, 515, 51
In 6 and 517, the control regarding the branch pipeline switching valves B1 to B4 and the main pipeline switching valves C1 to C4 is the same as in the first embodiment. The difference from the first embodiment is that control of the pressure-reducing pipeline switching valves D1 to D4 is added. However, in any step, the pressure reducing line switching valve D
1 to D4 are kept off. Therefore, the pressure reducing pipeline switching valves D1 to D4 are in the shut-off position, and the reservoir tank R1
And R2 are shut off. That is, this is the ABS
This is a control in which the ABS control is not performed based on the fact that the flag is off.

On the other hand, if the ABS flag is ON in step 5A1, in step 5A2, the branch pipeline switching valves B1 to B4, the main pipeline switching valves C1 to C4, and the pressure reducing pipeline switching valves D1 to D4 are all once set. Turn off and regenerative braking off. After that, predetermined ABS control is performed (step 5A3). ABS control means that when the wheels are about to lock, the wheel cylinder fluid pressure is reduced to temporarily reduce the braking torque, and when the wheels start to rotate, the wheel cylinder fluid pressure is increased again several times to 10 times per second. This control is to prevent the wheels from being locked repeatedly about once. Specifically, the branch pipeline switching valves B1 to B
4. Main pipeline switching valves C1 to C4 and pressure reducing pipeline switching valves D1 to
This is performed by switching D4 to three modes shown in Table 1, namely, "filling", "holding" and "relaxing".

[0042]

[Table 1]

In Table 1, in the "filling" mode, the branch line switching valves B1 to B4, the main line switching valves C1 to C4, and the pressure reducing line switching valves D1 to D4 are all turned off.
The master cylinder hydraulic pressure Pm is supplied to the hydraulic braking devices 4RL, 4FR, 4RR, and 4FL through the main line switching valves C1 to C4 at the communication positions. In the "hold" mode, the branch line switching valves B1 to B4 and the pressure reducing line switching valves D1 to D4 are off, and only the main line switching valves C1 to C4 are on. Accordingly, the wheel cylinder hydraulic pressure Pw at that time is held by shutting off the main pipeline switching valves C1 to C4. In the "relaxation" mode, the branch pipeline switching valves B1 to B4 are off, and the main pipeline switching valves C1 to C4 and the pressure reducing pipeline switching valves D1 to D4 are on. Therefore, the master cylinder hydraulic pressure Pm is shut off by the main line switching valves C1 to C4 at the shutoff position, and the liquid supplied to the hydraulic braking devices 4RL, 4FR, 4RR and 4FL is reduced to the pressure reducing line switching valve D1 at the communication position. Through D4 to be absorbed in the reservoir tanks R1 and R2. by this,
The hydraulic braking force is lost and the locked state of the wheels is released.

In the above-described ABS operation, the main line switching valves C1 to C4 act as filling valves for supplying hydraulic pressure to the hydraulic braking devices 4RL, 4FR, 4RR and 4FL, and the pressure reducing line switching valves D1 to D4. Acts as a release valve when releasing the hydraulic pressure. Here, since the main line switching valves C1 to C4 are originally provided independently of the ABS control, A is only required by adding only the pressure reducing line switching valves D1 to D4.
A BS control function can be added.

When the brake pedal 1 is returned, the brake switch 10 is turned off, so that steps 512 and 517 described above are executed, and the state returns to the state before the brake operation was performed. Further, since the master cylinder hydraulic pressure Pm becomes a negative pressure, the hydraulic braking devices 4RL, 4RR, 4FL, and 4FL
The liquid sent to the FR is the main line switching valve C1 and the check valve 71, the main line switching valve C3 and the check valve 74, the main line switching valve C4 and the check valve 75, and the main line switching valve C, respectively.
2 and is returned to the master cylinder 2 through the check valve 72. The liquid absorbed by the stroke simulators S1 and S2 is returned to the master cylinder 2 through the check valves 73 and 76, respectively. The liquid absorbed in the reservoir tanks R1 and R2 is supplied to the check valves 77 and 7 respectively.
8, the pump 14 and 15 forcibly return to the master cylinder 2.

As in the first embodiment, the changes of the master cylinder hydraulic pressure Pm, the regenerative braking force, the wheel cylinder hydraulic pressure Pw, and the pedal stroke with respect to the time t based on the above operation are shown in the graph of FIG. . The "D" column in the table below the pedal stroke graph indicates the operating state of the pressure reducing pipeline switching valves D1 to D4.

<< Third Embodiment >> FIG. 3 shows a third embodiment of the present invention.
FIG. 3 is a diagram showing a configuration of an electric vehicle braking device according to an embodiment of the present invention. The device has a configuration in which another switching valve is additionally provided to the electric vehicle braking device according to the first embodiment. In the figure, a hydraulic control system 3A includes a pair of common switching valves A1 and A2, a pair of main pipeline switching valves C1 and C2, a pair of branch pipeline switching valves B1 and B2, and a check valve 71.
To 73, and a stroke simulator S1. On the other hand, the hydraulic control system 3B includes a pair of common switching valves A
3 and A4, a pair of main pipeline switching valves C3 and C4, a pair of branch pipeline switching valves B3 and B4, check valves 74 to 76, and a stroke simulator S2. The difference between the braking device according to the third embodiment and the braking device according to the first embodiment (FIG. 1) is that the common switching valves A1, A2, A3, and A4 respectively correspond to the master cylinder 2 and the main line switching valve C.
1, C2, C3 and C4.

Next, a braking control operation of the braking device for an electric vehicle according to the third embodiment configured as described above will be described with reference to flowcharts of FIGS. The notation “A” in the flowchart means the common switching valves A1 to A4. When the process is started, the brake controller 11 determines whether the brake switch 10 is on (Step 701). Here, when the brake operation is not performed, since the brake switch 10 is off, the regenerative braking off state is maintained (step 713), and the common switching valves A1 to A4 and the branch pipeline switching valves B1 to B4. B4 and the main pipeline switching valves C1 to C4 are kept off (step 719). As a result, the common switching valve A
1 to A4 and the main pipeline switching valves C1 to C4 are in the communicating position, and the branch pipeline switching valves B1 to B4 are in the shutoff position. Therefore, the master cylinder 2 and the hydraulic braking devices 4RL, 4RR,
4FL and 4FR are in communication with each other, that is, in a state of waiting for a brake operation.

Next, when the brake is operated, that is, when the brake pedal 1 is depressed, the brake switch 10 is turned on, and the process proceeds from step 701 to step 702. In step 702, the brake controller 11
Fetches from the motor controller 12 information on the maximum regenerative braking force RBmax available at that time. When this RBmax is 0 (Y in step 703), the brake controller 11 turns off the regenerative braking (step 713), and switches the common switching valves A1 to A4 and the main pipeline switching valve C1.
To C4 in the communication position, and the branch line switching valves B1 to B4
In the shut-off position. Therefore, when the regenerative braking force cannot be used, the entire braking force is borne by the hydraulic braking force.
At this time, the stroke simulators S1 and S2 do not consume the liquid.

If the maximum regenerative braking force RBmax is not 0 (N in step 703), the brake controller 11 takes in the value of the master cylinder hydraulic pressure Pm from the hydraulic pressure sensor 91 and sets the wheel cylinder hydraulic pressure in the hydraulic braking devices 4RR and 4FL. The value of the pressure Pw is determined by the hydraulic pressure sensors 92 and 9
3 (step 704). Next, the brake controller 11 compares the hydraulic pressure _PRBmax for obtaining the hydraulic braking force corresponding to the maximum regenerative braking force RBmax with the master cylinder hydraulic pressure Pm (Step 705), and the master cylinder hydraulic pressure Pm becomes P _{If RBmax} has not been reached, a value obtained by multiplying master cylinder hydraulic pressure Pm by a predetermined coefficient α is output to motor controller 12 as regenerative braking force command value RB (step 714). The motor controller 12 receives this and performs regenerative braking by the motor 6.

Next, in step 715, the brake controller 11 compares the master cylinder pressure Pm, the invalid pressure P _0. Master cylinder hydraulic pressure Pm becomes invalid pressure P ₀
In the following cases, the brake controller 11 proceeds to step 719, maintains the common switching valves A1 to A4 and the main pipeline switching valves C1 to C4 in the communicating positions, and sets the branch pipeline switching valves B1 to B1.
B4 is maintained in the blocking position. Therefore, the master cylinder hydraulic pressure Pm is directly used as the hydraulic braking device 4RL, 4RR, 4FL.
And 4FR, and the invalid stroke is reduced.

[0052] When the master cylinder pressure Pm exceeds the invalid pressure _{P 0,} the brake controller 11 step 718
And while maintaining the common switching valves A1 to A4 in the off state, the branch pipeline switching valves B1 to B4 and the main pipeline switching valves C1 to C1.
C4 is turned on. Thereby, the branch pipeline switching valve B
1 to B4 are in the communicating position, and the main pipeline switching valves C1 to C4 are in the shutoff position. Therefore, the wheel cylinder hydraulic pressure Pw is maintained in that state, and the stroke simulators S1 and S2 absorb the hydraulic pressure and the liquid amount from the master cylinder 2 instead. Due to this absorption, the amount of fluid that would be consumed if the braking force corresponding to the regenerative braking force was generated only by the hydraulic braking force is consumed, and the brake pedal 1 is given a corresponding pedal stroke. Therefore, there is no difference in pedal stroke between the case where the regenerative braking force is used and the case where only the hydraulic braking force is used, so that the brake feeling does not feel uncomfortable.

Returning to step 705, if the master cylinder hydraulic pressure Pm is _{equal to} or higher than the hydraulic pressure P _RBmax (that is, if the regenerative braking force alone is not enough), the brake controller 1
1 indicates that the regenerative braking force command value RB is equal to the maximum regenerative braking force RBmax.
The regenerative braking force command value RB is output (step 706). The motor controller 12 receives this and performs regenerative braking by the motor 6.

Subsequently, at step 707, the brake controller 11 sets the master cylinder hydraulic pressure Pm to (Pw
−P ₀ ) + P _{RB It} is determined whether or not it is larger than _RB . here,
P _RB is a hydraulic pressure for obtaining a hydraulic braking force equivalent to RB, and (Pw−P ₀ ) is a hydraulic pressure actually contributing to the generation of the hydraulic braking force. That is, in step 707, the master cylinder hydraulic pressure Pm corresponding to the required braking force is
It is determined whether the braking force is greater than the total braking force currently output (= hydraulic braking force + regenerative braking force). Here, if the master cylinder pressure Pm is greater than _{(Pw-P 0) + P} RB, the brake controller 11 proceeds to step 712, if it is not larger, or "less", the brake controller 11 proceeds to step 708.

[0055] In step 708, the brake controller 11, the master cylinder hydraulic pressure Pm _(Pw-P 0)
+ Determines whether equal P _RB. If they are equal, the process proceeds to step 709, where the brake controller 11 turns off the common switching valves A1 to A4 and the branch pipeline switching valves B1 to B4, and turns on the main pipeline switching valves C1 to C4. Thereby, the branch line switching valves B1 to B4 and the main line switching valve C1
To C4 are all in the blocking position. Therefore, the current wheel cylinder hydraulic pressure Pw is maintained. If the master cylinder pressure Pm is _(Pw-P 0) is not equal to + P _RB, that is, when the master cylinder pressure Pm is _{(Pw-P 0) + P} RB smaller than, the P _RB = Pm-Pw (step 71
0), a regenerative braking force command value R obtained by multiplying P _RB by a predetermined coefficient α
B is output (step 711). Thus, the regenerative braking force is adjusted (suppressed).

On the other hand, in step 712, the brake controller 11 determines that the wheel cylinder hydraulic pressure Pw is (1).
/ 2) It is determined whether or not it is not less than Pm. Pw is (1 /
2) If Pw is equal to or greater than Pm, go to step 717, where Pw is (1)
/ 2) If it is less than Pm, go to step 716. The significance of step 712 is that the stroke simulator S
(1/1/2) as a measure of the hydraulic pressure absorbed in S1 and S2.
2) If Pm is equal to or less than the wheel cylinder hydraulic pressure Pw, there is no point in performing the process of step 716,
This is to avoid this and proceed to step 717. In step 717, the brake controller 11
The common switching valves A1 to A4 and the branch pipeline switching valves B1 to B4 are turned off, and the main pipeline switching valves C1 to C4 are switched by a pulse train drive signal to control the output. Thereby, the common switching valves A1 to A4
Is a communication position, the branch pipeline switching valves B1 to B4 are in a shutoff position, and the main pipeline switching valves C1 to C4 increase the output hydraulic pressure (wheel cylinder hydraulic pressure Pw) while repeating the communication and the shutoff. With such duty control, the hydraulic braking force can be freely controlled.

On the other hand, in step 716, the brake controller 11 turns on the common switching valves A1 to A4 and the branch pipeline switching valves B1 to B4, and switches the main pipeline switching valves C1 to C4 by a pulse train drive signal. Drive to control the output duty. This allows
The common switching valves A1 to A4 are in the shut-off position, the branch line switching valve B1
To B4 are communication positions, and the main pipeline switching valves C1 to C4 repeat strokes and cutoffs while repeating the stroke simulator S.
The wheel cylinder hydraulic pressure Pw is increased by the hydraulic pressure absorbed by 1 and S2. In the control of step 716, when the vehicle speed decreases due to braking and the regenerative braking force starts to decrease, a hydraulic braking force that compensates for this is generated using the hydraulic pressure absorbed by the stroke simulators S1 and S2. Thus, there is an effect that the amount of change in the pedal stroke is reduced.

When the brake pedal 1 is returned, the brake switch 10 is turned off, so that steps 713 and 719 described above are executed, and the state returns to the state before the brake operation was performed. Further, since the master cylinder hydraulic pressure Pm becomes a negative pressure, the hydraulic braking devices 4RL, 4RR, 4FL, and 4FL
The liquids sent to the FRs are respectively the common switching valve A1, the main line switching valve C1 and the check valve 71, the common switching valve A3, the main line switching valve C3 and the check valve 74, the common switching valve A4, the main line switching. A valve C4 and a check valve 75, and a common switching valve A2,
It is returned to the master cylinder 2 through the main line switching valve C2 and the check valve 72. In addition, the stroke simulator S1
And the liquid absorbed by S2 is returned to master cylinder 2 through check valves 73 and 76, respectively.

FIG. 10 shows the master cylinder hydraulic pressure Pm, regenerative braking force, and wheel cylinder hydraulic pressure Pw based on the above operation.
7 is a graph showing changes in pedal stroke and time t. In the graph of the pedal stroke, the solid line indicates the characteristic at the time of braking using regenerative braking together,
The broken line indicates the characteristic at the time of braking only with hydraulic braking without using regenerative braking. The “A”, “B”, and “C” columns in the table below the pedal stroke graph are:
Common switching valves A1 to A4, branch pipeline switching valves B1 to B1
The operation state corresponding to the graph of B4 and the main pipeline switching valves C1 to C4 is shown. The “D” column relates to a fourth embodiment described later, and is not relevant to the present embodiment.

In FIG. 10, from time 0 to t1,
This corresponds to the operation of executing the step 719 and ending in the flowchart of FIG. From time t1 to t2,
This corresponds to an operation of executing step 718 and terminating. The operation from time t2 to t3 corresponds to the operation of executing step 717 and ending. The operation from time t3 to t4 corresponds to the operation of executing step 709 and ending. Time t4
Steps from t5 to t5 correspond to the operation of executing step 716 and ending. From time t5 to t6, step 71
7 corresponds to an operation of ending the execution. The operation after time t6 corresponds to the operation of executing step 719 and ending. As is clear from the comparison with FIG. 9, the pedal stroke is further improved by the control effect of the above-described step 716, and when only the hydraulic braking is performed (dashed line) and when the regenerative braking is used together (solid line), There is almost no difference. Therefore, regardless of whether regenerative braking is used or not, the pedal stroke is always substantially constant.

<< Fourth Embodiment >> FIG. 4 shows a fourth embodiment of the present invention.
It is a figure which shows the structure of the braking device for electric vehicles by 3rd Embodiment, Comprising: The said device has the structure which added ABS to the braking device for electric vehicles in 3rd Embodiment. In the figure, a hydraulic control system 3A includes a pair of common switching valves A1 and A2, and a pair of main line switching valves C1 and C1.
2. A pair of branch line switching valves B1 and B2, a pair of pressure reducing line switching valves D1 and D2, check valves 71 to 73 and 77, a stroke simulator S1, and a reservoir tank R
1 is provided. On the other hand, the hydraulic control system 3B includes a pair of common switching valves A3 and A4 and a pair of main pipeline switching valves C3 and C3.
4, a pair of branch line switching valves B3 and B4, a pair of pressure reducing line switching valves D3 and D4, check valves 74 to 76 and 78, a stroke simulator S2, and a reservoir tank R
2 is provided.

In FIG. 4, the pressure reducing line switching valves D1 and D1
2 are solenoid valves provided between the reservoir tank R1 and the common switching valves A1 and A2, respectively.
It has a communication position for communicating the master cylinder 2 and the reservoir tank R1 with each other via the first and A2, and a shutoff position for shutting off the communication position. In addition, the check valve 77 and the pump 14
Are connected in series with each other in the same liquid flow direction, and are provided between the master cylinder 2 and the reservoir tank R1 to enable forced return of the liquid from the reservoir tank R1 to the master cylinder 2. I have.

The pressure-reducing pipeline switching valves D3 and D4 are solenoid valves provided between the reservoir tank R2 and the common switching valves A3 and A4, respectively.
4 has a communication position for communicating the master cylinder 2 and the reservoir tank R2 with each other via the cylinder 4, and a blocking position for blocking the communication position. The check valve 78 and the pump 15 are connected in series with each other in the same liquid flow direction, and are provided between the master cylinder 2 and the reservoir tank R2, forcing the liquid from the reservoir tank R2 to the master cylinder 2. It is possible to return. On the other hand, for the ABS control, the front wheels 5F
Speed sensors 16F and 16R are provided for both the rear wheels 5R and the rear wheels 5R, respectively, and these are connected to the brake controller 11. Other configurations are the same as those of the third embodiment, and a description thereof will be omitted.

Next, the braking control operation of the braking device for an electric vehicle according to the fourth embodiment configured as described above will be described with reference to the flowcharts of FIGS. The notation “D” in the flowchart means the pressure-reducing pipeline switching valves D1 to D4. This flowchart is
The difference from the flowchart (FIG. 7) in the third embodiment is the contents of steps 7A1, 7A2, and 7A3 relating to the ABS control described below, and steps 709 and 716 to 719 relating to the output. The other steps are the same, and the description is omitted here.

When the brake switch 10 is turned on from off, the brake controller 11 proceeds from step 701 to step 7A1, and determines whether the ABS flag is on or off. In step 701 immediately after the start of the braking operation, the normal ABS flag is off, and the process proceeds directly to step 702 and subsequent steps. Then, in steps 709 and 716 to 719, the control regarding the common switching valves A1 to A4, the branch pipeline switching valves B1 to B4, and the main pipeline switching valves C1 to C4 is the same as in the third embodiment. The difference from the third embodiment is that control of the pressure-reducing pipeline switching valves D1 to D4 is added. However, in any step, the pressure-reducing pipeline switching valves D1 to D4 are kept off. Therefore, the pressure reducing line switching valves D1 to D4 are in the shut-off position, and the reservoir tanks R1 and R2 are shut off. That is, this is a control in which the ABS control is not performed based on the fact that the ABS flag is off.

On the other hand, if the ABS flag is ON in step 7A1, in step 7A2, the common switching valves A1 to A4, the branch pipeline switching valves B1 to B4, the main pipeline switching valves C1 to C4, and the pressure reducing pipeline switching. The valves D1 to D4 are all turned off once, and the regenerative braking is turned off.
Then, predetermined ABS control is performed (step 7A3). In the ABS control, the common switching valves A1 to A4, the branch line switching valves B1 to B4, the main line switching valves C1 to C4, and the pressure reducing line switching valves D1 to D4 are set as shown in Table 1,
It is performed by switching to three modes of “hold” and “relax”.

[0067]

[Table 2]

In Table 2, in the "fill-in" mode, the common switching valves A1 to A4, the branch pipeline switching valves B1 to B4, the main pipeline switching valves C1 to C4, and the pressure reducing pipeline switching valves D1 to D4 are all turned off. Therefore, the common switching valves A1 to A
The master cylinder hydraulic pressure Pm is supplied to the hydraulic braking devices 4RL, 4FR, 4RR, and 4FL through the valve 4 and the main pipeline switching valves C1 to C4. In the "hold" mode, the branch pipeline switching valves B1 to B4, the main pipeline switching valves C1 to C4, and the pressure reducing pipeline switching valves D1 to D4 are off, and only the common switching valves A1 to A4 are on. Therefore, by shutting off the common switching valves A1 to A4, the wheel cylinder hydraulic pressure Pw at that time is held. In the "relaxation" mode, the branch pipeline switching valves B1 to B4 and the main pipeline switching valves C1 to C4 are off, and the common switching valves A1 to A4 are turned off.
And the pressure-reducing pipeline switching valves D1 to D4 are turned on. Therefore,
The master cylinder hydraulic pressure Pm is the common switching valve A1
Shut off by A4, hydraulic braking devices 4RL, 4FR,
The liquid supplied to 4RR and 4FL is absorbed by the reservoir tanks R1 and R2 through the main line switching valves C1 to C4 and the pressure reducing line switching valves D1 to D4 at the communicating positions. As a result, the hydraulic braking force is lost, and the locked state of the wheels is released.

In the above ABS operation, the common switching valve A
1 to A4 and the main line switching valves C1 to C4 act as filling valves for supplying the hydraulic pressure to the hydraulic braking devices 4RL, 4FR, 4RR and 4FL, and the pressure reducing line switching valves D1 to D4 release the hydraulic pressure. Acts as a relief valve for the case. Here, the common switching valves A1 to A4 and the main pipeline switching valves C1 to C4 are originally A
Since it is provided irrespective of the BS control, it is necessary to add only the pressure reducing line switching valves D1 to D4 to achieve A
A BS control function can be added. Further, since the pressure-reducing pipeline switching valves D1 to D4 are provided to be branched from the pipeline connecting the common switching valves A1 to A4 and the main pipeline switching valves C1 to C4, the main pipeline switching valves C1 to C4 are controlled during the ABS control. While the C4 is always kept off (communication position), the common switching valves A1 to A
4 can be turned on / off and used as a substantial filling valve. Therefore, the frequency of opening and closing of the main pipeline switching valves C1 to C4 during the brake operation can be reduced, and the durability of the main pipeline switching valves C1 to C4 can be improved.

When the brake pedal 1 is returned, the brake switch 10 is turned off, so that the above-described steps 713 and 719 are executed, and the state returns to the state before the brake operation is performed. Further, since the master cylinder hydraulic pressure Pm becomes a negative pressure, the hydraulic braking devices 4RL, 4RR, 4FL, and 4FL
The liquid sent to the FR is the main line switching valve C1 and the check valve 71, the main line switching valve C3 and the check valve 74, the main line switching valve C4 and the check valve 75, and the main line switching valve C, respectively.
2 and is returned to the master cylinder 2 through the check valve 72. The liquid absorbed by the stroke simulators S1 and S2 is returned to the master cylinder 2 through the check valves 73 and 76, respectively. The liquid absorbed in the reservoir tanks R1 and R2 is supplied to the check valves 77 and 7 respectively.
8, the pump 14 and 15 forcibly return to the master cylinder 2.

As in the third embodiment, changes in the master cylinder hydraulic pressure Pm, the regenerative braking force, the wheel cylinder hydraulic pressure Pw, and the pedal stroke with respect to the time t based on the above operation are shown in the graph of FIG. . The "D" column in the table below the pedal stroke graph indicates the operating state of the pressure reducing pipeline switching valves D1 to D4.

The electric vehicle braking device in each of the above embodiments can be realized by using the respective valves (common switching valves A1 to A4, branch pipe switching valves B1 to B4,
Since the main pipeline switching valves C1 to C4 and the pressure reducing pipelines D1 to D4) are directional switching valves, an inexpensive configuration can be achieved. Further, in each of the above embodiments, each valve is a two-position valve having a shutoff position and a communication position, but a three-position valve may be used. Further, the braking device for an electric vehicle in each of the above embodiments is applied to a four-wheel drive vehicle, but it is needless to say that the same can be applied to a front wheel drive vehicle or a rear wheel drive vehicle.

[0073]

The present invention configured as described above has the following effects. According to the brake device for an electric vehicle of the present invention, when a regenerative braking force can be generated during a brake operation, the output hydraulic pressure of the master cylinder is prevented from being transmitted to the hydraulic brake device, and the stroke is reduced. Let the simulator absorb the output hydraulic pressure of the master cylinder. Also,
When the output hydraulic pressure of the master cylinder reaches the hydraulic pressure corresponding to the limit value of the regenerative braking force at the time of the brake operation, the absorption of the liquid to the stroke simulator is stopped, and the regenerative braking is performed by switching the main pipeline switching valve. A hydraulic braking force that compensates for the lack of braking force is generated. Therefore, with a simple configuration using the branch line switching valve and the main line switching valve, the regenerative braking force can be effectively used, and the hydraulic pressure and the liquid amount equivalent to the regenerative braking force are absorbed by the stroke simulator. Thereby, the same pedal stroke as that at the time of braking only with the hydraulic braking force can be obtained.

According to the brake device for an electric vehicle of the present invention, when only the hydraulic braking is performed, the master cylinder and the hydraulic braking device are communicated with each other by the main line switching valve in the demagnetized state. Since the switching valve shuts off the master cylinder and the stroke simulator, the output hydraulic pressure of the master cylinder can be transmitted to the hydraulic braking device without operating the stroke simulator. Therefore, the pedal stroke in the case of only the hydraulic braking is substantially equal to that in the case of the combined use of the regenerative braking, so that the uncomfortable feeling of the pedal stroke can be eliminated.

According to the third aspect of the present invention, the output hydraulic pressure of the master cylinder is supplied to the hydraulic braking device through the main pipeline switching valve until the hydraulic pressure of the hydraulic braking device reaches the invalid pressure. Also, even during regenerative braking, the invalid stroke of the hydraulic braking device can be reduced.

According to the braking device for an electric vehicle of the fourth aspect, the output hydraulic pressure supplied from the main pipeline switching valve to the hydraulic braking device can be easily controlled by the duty control.

According to the brake device for an electric vehicle of the fifth aspect, the hydraulic pressure and the fluid amount absorbed by the stroke simulator are compensated for when the regenerative braking force starts decreasing due to a decrease in vehicle speed or the like. Released as power. Therefore, a change in pedal stroke can be reduced.

According to the brake device for an electric vehicle of the present invention, the main line switching valve acts to supply the hydraulic pressure to the hydraulic braking device as a “fill valve” in the ABS control, and the pressure reducing line switching valve is “ As a "relaxation valve", it acts to relax the hydraulic pressure of the hydraulic brake system, so it is simple to add a pressure reducing line switching valve using the main line switching valve provided regardless of whether ABS control is performed. With such a simple structure, an ABS function can be provided.

According to the brake device for an electric vehicle of the present invention, the main line switching valve and the common switching valve act as a "fill valve" in the ABS control to supply the hydraulic pressure to the hydraulic braking device, and the pressure reducing line The switching valve acts as a "relaxation valve" to relax the hydraulic pressure of the hydraulic braking device. Therefore, the ABS function can be provided only by adding the pressure reducing line switching valve by using the main line switching valve and the common switching valve provided regardless of the presence or absence of the ABS control.

According to the brake system for an electric vehicle of the present invention, during the ABS control, the common switching valve is used as a "fill valve" while the main pipeline switching valve is maintained at the communicating position. Therefore,
The switching frequency of the main pipeline switching valve during the brake operation can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a hydraulic system and an electric system of a braking device for an electric vehicle according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a hydraulic system and an electric system of a braking device for an electric vehicle according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a hydraulic system and an electric system of a braking device for an electric vehicle according to a third embodiment of the present invention.

FIG. 4 is a diagram showing a hydraulic system and an electric system of a braking device for an electric vehicle according to a fourth embodiment of the present invention.

FIG. 5 is a flowchart showing a braking control operation in the electric vehicle braking device according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a braking control operation in the electric vehicle braking device according to the second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a braking control operation in the braking device for an electric vehicle according to the third embodiment of the present invention.

FIG. 8 is a flowchart showing a braking control operation in a braking device for an electric vehicle according to a fourth embodiment of the present invention.

FIG. 9 is a graph showing changes in master cylinder hydraulic pressure Pm, regenerative braking force, wheel cylinder hydraulic pressure Pw, pedal stroke with respect to time t, and the like in the electric vehicle braking devices according to the first and second embodiments of the present invention. is there.

FIG. 10 is a graph showing changes in master cylinder hydraulic pressure Pm, regenerative braking force, wheel cylinder hydraulic pressure Pw, pedal stroke with respect to time t, and the like in the electric vehicle braking devices according to the third and fourth embodiments of the present invention. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Master cylinder 3A, 3B Hydraulic pressure control system 4RL, 4RR, 4FL, 4FR Hydraulic braking device 5R Rear wheel 5F Front wheel 6 Motor 11 Brake controller 12 Motor controller A1-A4 Common switching valve B1-B4 Branch pipe switching Valves C1 to C4 Main line switching valve D1 to D4 Pressure reducing line switching valve S1, S2 Stroke simulator R1, R2 Reservoir tank

Claims (8)

[Claims] 1. A hydraulic braking device which is operated by an input hydraulic pressure from a master cylinder is provided at a front wheel and a rear wheel, and a motor capable of generating a regenerative braking force by a brake operation is connected to at least one of the front wheel and the rear wheel. An electric vehicle braking device, comprising: a communication position provided between the master cylinder and the hydraulic braking device for transmitting input hydraulic pressure from the master cylinder; and blocking transmission of the input hydraulic pressure. A main line switching valve having a shut-off position, and a line connecting the main line switching valve and the master cylinder connected to the master cylinder via a branch line to transmit an input hydraulic pressure from the master cylinder. A branch line switching valve having a communication position to be closed and a blocking position for blocking transmission of the input hydraulic pressure, and connected to the master cylinder via the branch line switching valve. A stroke simulator that absorbs a fluid amount and a fluid pressure required when the regenerative braking force at the time of the regenerative braking is generated as a hydraulic braking force; and, when a regenerative braking force can be generated during a brake operation, The branch line switching valve is set to the communicating position from the shut-off position, the main line switching valve is set to the shut-off position, and the output hydraulic pressure of the master cylinder is adjusted to the hydraulic pressure corresponding to the limit value of the regenerative braking force during the brake operation. A control unit for setting the branch line switching valve to the shut-off position and switching the main line switching valve to generate a hydraulic braking force that compensates for the lack of the regenerative braking force. A braking device for an electric vehicle. 2. The braking device for an electric vehicle according to claim 1, wherein the branch line switching valve and the main line switching valve are solenoid valves, and are respectively in a shut-off position and a communication position in a demagnetized state. . 3. The control unit, when a regenerative braking force can be generated, sets the branch pipeline switching valve to the shut-off position and sets the main pipeline until the hydraulic pressure of the hydraulic braking device reaches an invalid pressure. The braking device for an electric vehicle according to claim 1, wherein the switching valve is set to a communication position. 4. The braking device for an electric vehicle according to claim 1, wherein when the shortage of the regenerative braking force is compensated for by a hydraulic braking force, the main pipeline switching valve is switched by duty control. 5. A communication position which is provided between the branch line switching valve and the main line switching valve and the master cylinder and transmits an input hydraulic pressure from the master cylinder, and a communication position for transmitting the input hydraulic pressure. A common switching valve having a shut-off position for shutting off, when the regenerative braking force starts to decrease, on the condition that the hydraulic pressure absorbed by the stroke simulator is higher than the hydraulic pressure of the hydraulic braking device. The switching valve is in the shut-off position, the branch pipeline switching valve is in the communicating position, and the main pipeline switching valve uses the hydraulic pressure absorbed by the stroke simulator to compensate for the lack of the regenerative braking force. 2. The braking device for an electric vehicle according to claim 1, wherein the switching control is performed to generate the braking force. 6. A pressure reducing line switching valve provided in a pressure reducing line branched from a downstream side of the main line switching valve and connected to a reservoir tank, for shutting off and communicating the hydraulic braking device and the reservoir tank. The braking device for an electric vehicle according to claim 1, further comprising: 7. A pressure reducing line switching valve provided in a pressure reducing line branched from a downstream side of the common switching valve and connected to a reservoir tank, for shutting off / communicating the hydraulic braking device and the reservoir tank. The braking device for an electric vehicle according to claim 5, wherein the braking device is provided. 8. The pressure reducing line provided with the pressure reducing line switching valve is branched from a line connecting the main line switching valve and the common switching valve. Braking device for electric vehicles.