JP4590709B2 - Brake device for vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle brake device that performs control so that a dither current (vibration current) is applied to a current that flows through an actuator for driving a brake.
[0002]
[Prior art]
When the brake pedal is depressed by the driver, the vehicular brake device sends an instruction current corresponding to the pedaling force to the brake driving actuator, and generates a braking torque corresponding to the pedaling force by the operation of the actuator. The relationship between the command current applied to the actuator and the braking torque has hysteresis, that is, between the braking torque when increasing the command current and the braking torque when decreasing the command current as shown in FIG. Since there is a deviation, conventionally, a hysteresis is eliminated by adding a dither current to the command current so that the command current and the braking torque are in a proportional relationship.
[0003]
[Problems to be solved by the invention]
However, in order to obtain a constant braking torque, it is necessary to always add an instruction current proportional to the braking torque, and a corresponding amount of current consumption is required.
[0004]
In view of the above points, the present invention has an object to reduce current consumption when obtaining a constant braking torque.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a dither current is superimposed on an instruction current determined in response to depression of the brake pedal (1), and a current obtained by superimposing the dither current on the instruction current. Is output to the brake drive actuators (8 to 11) as an output current, and in the vehicle brake device configured to generate a braking force by driving the brake drive actuator, the instruction current on which the dither current is superimposed The line (A) showing the relationship between the braking torque and the braking torque is a line (B) having a hysteresis showing the relation between the command current and the braking torque when the dither current is not superimposed. Set between the rising line showing the relationship between the command current and braking torque and the falling line showing the relationship between the command current and braking torque when the command current is gradually lowered Are, when the state of depression of the brake pedal is maintained, it stops the superposition of the dither current, than when the depression of the brake pedal is started to be maintained to reduce the indicator current and the reduced It is characterized in the score flow to the brake driving actuator as a command current output current.
[0006]
In this way, when the depression of the brake pedal is maintained, the consumption current can be reduced by stopping the superposition of the dither current and reducing the command current.
[0007]
In the second aspect of the invention, if there is a change in the depression of the brake pedal from the state where the depression is maintained, the reduced instruction current is returned to the instruction current when the depression of the brake pedal starts to be maintained, and the dither The current superposition is started again, and the current obtained by superimposing the dither current on the command current is supplied as an output current to the brake driving actuator.
[0008]
In this way, once the brake pedal depression has changed after the brake pedal depression has been maintained, the reduced instruction current is restored and the dither current superimposition is started again. It is possible to return the relationship between the current and the braking torque to a proportional relationship without hysteresis.
[0009]
In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
FIG. 1 shows a schematic configuration of a vehicle brake device to which an embodiment of the present invention is applied. The configuration of the brake device will be described below based on this figure.
[0011]
As shown in FIG. 1, the brake device receives a brake pedal 1 that is operated by a driver, a pedaling force sensor 2 that detects a pedaling force when the brake pedal 1 is depressed, and a detection signal from the pedaling force sensor 2. An electronic control unit (hereinafter referred to as ECU) 3 and a brake driving actuator (braking force generating unit) that is provided for each of the wheels 4-7 and is driven by the ECU 3 to generate a braking force on each of the wheels 4-7. 8 to 11 are provided.
[0012]
The ECU 3 determines an instruction current corresponding to the pedal depression force, that is, a current to be supplied to the brake driving actuators 8 to 11 based on a detection signal from the pedal force sensor 2, and the brake driving actuators 8 to 8 by supplying the instruction current. 11 is controlled.
[0013]
The brake driving actuators 8 to 11 are constituted by, for example, a motor and a disc brake or a drum brake driven by the motor, and are configured so that the braking force can be adjusted by adjusting the energization amount to the motor. When an instruction current is flowed from the ECU 3, the brake driving actuators 8 to 11 generate a braking torque according to the instruction current.
[0014]
With these configurations, when the driver depresses the brake pedal 1, the pedal effort is detected by the pedal effort sensor 2, and calculation is performed by the ECU 3 based on the pedal effort, and further, An output current corresponding to the result is supplied to the brake driving actuators 8 to 11 so that the brake control corresponding to the depression of the brake pedal 1 is performed.
[0015]
Next, in the brake device described above, a method for setting an output current flowing through the brake driving actuators 8 to 11 will be described with reference to a flowchart shown in FIG.
[0016]
First, as shown in step 100, a braking instruction value is input. The braking instruction value is input by the ECU 3 based on a detection signal from the pedaling force sensor 2, and a value corresponding to the braking force corresponding to the pedaling force is input. In step 110, the input braking instruction value is differentiated to determine the fluctuation ratio of the braking instruction value with respect to time. The differential value of the braking instruction value indicates a change in depression of the brake pedal 1, and if the differential value is small, there is almost no change in the depression of the brake pedal 1, that is, a state where the depression of the brake pedal 1 is maintained. Represents.
[0017]
In step 120, it is determined whether the result of the differential operation is greater than a constant A. That is, it is determined whether or not the depression of the brake pedal 1 is maintained. If the determination is affirmative, it is assumed that there is a change in the depression of the brake pedal 1, and the dither amplitude (the amplitude of the dither current) is set to a large value in step 130. I do. Here, the output current is calculated according to the equation: output current = braking instruction value × constant B + dither amplitude large. In this case, the braking command value × constant B corresponds to the command current, and a value obtained by adding a dither current having a large amplitude to the command current is set as the output current.
[0018]
On the other hand, if a negative determination is made in step 120, assuming that the depression of the brake pedal 1 is maintained, the dither amplitude is set to a small value in step 150, and then the process proceeds to step 160 where the output current is calculated. Here, the output current is calculated according to output current = braking instruction value × constant B × constant C + dither amplitude small. However, the constant C is a number less than 1.
[0019]
The small dither amplitude at this time means that the amplitude of the dither current is very small, and means that the dither current is not superimposed. That is, when the depression of the brake pedal 1 is maintained, the dither current is not superimposed on the command current. In this case, since the braking command value × constant B × constant C corresponds to the command current and the constant C is appropriately set to a number less than 1, the depression of the brake pedal 1 is changed. It is calculated so that the indicated current is lower when the state is maintained than when it is maintained. A value obtained by adding a dither current having a small amplitude to the reduced instruction current is set as an output current.
[0020]
In step 170, the set output current is supplied to the brake driving actuators 8 to 11, and the process is repeated.
[0021]
In the brake device that performs such an operation, the relationship among the pedal depression force, the instruction current, the dither current, the braking force, and the consumption current when the brake pedal 1 is depressed is shown in the timings of FIGS. Shown in the chart. Based on this figure, the control method of the command current in this brake device is demonstrated.
[0022]
First, when the brake pedal 1 is depressed during the period t1 to t2 in FIG. 3, the pedal effort increases as shown in FIG. The increase in the pedal effort is detected by the pedal effort sensor 2, and the instruction current is calculated by the ECU 3 based on the detection signal from the pedal effort sensor 2. Then, as shown in FIG. 3C, the command current shows the same change as the depression of the brake pedal 1 and increases.
[0023]
When the command current is changing, a large dither amplitude is set as shown in FIG. 3B, and the dither current is superimposed on the command current as shown in FIG. A current obtained by superimposing a dither current on the command current is supplied to the brake drive actuators 8 to 11 as an output current (current consumption). At this time, since the dither current is superimposed on the command current, the relationship between the command current and the braking force is a proportional relationship having no hysteresis, and the braking force is equal to the command current and the braking current as shown in FIG. Similarly rises.
[0024]
Next, when the depression of the brake pedal 1 is maintained during the period t2 to t3 in FIG. 3, the pedal depression force is maintained as shown in FIG. Thereby, as shown in FIG.3 (c), the raise of instruction | indication current also stops.
[0025]
At this time, if it is detected that the pedal effort is maintained based on the detection signal from the pedal effort sensor 2, a small dither amplitude is set as shown in FIG. 3B, and the dither current is superimposed on the command current. As shown in FIGS. 3 (c) and 3 (e), the command current is decreased as compared with the time when the pedal effort is started to be maintained. Therefore, during this period t2 to t3, the command current is supplied to the brake drive actuators 8 to 11 as an output current (current consumption).
[0026]
The purpose of this operation will be described with reference to FIG. FIG. 4 shows the relationship between the command current and the braking torque. The relationship when the dither current is superimposed on the command current is indicated by the line A indicated by the solid line, and the command B is indicated by the line B indicated by the dotted line. On the other hand, the relationship when the dither current is not superimposed is shown.
[0027]
In FIG. 4, (a) represents the relationship between the command current and the braking torque during the period t2 to t3. During this period t2 to t3, that is, while the depression of the brake pedal 1 is maintained, as described above, the superposition of the dither current is stopped and the command current is reduced. This is because when the dither current is not superimposed, the relationship between the command current and the braking torque has hysteresis as shown by the line B in FIG. 4A, and the braking torque changes even if the command current changes. It is a thing that does not use. That is, when the depression of the brake pedal 1 is maintained, it is only necessary to keep the braking force constant. Therefore, if the superposition of the dither current is stopped during the period t2 to t3, the instruction current is changed as indicated by the arrow in the figure. Even if it is reduced, the braking torque can be kept constant.
[0028]
By adopting such an operation, when the brake pedal 1 is kept depressed, the instruction current can be reduced as shown by the hatched portions in FIGS. 3C and 3E. The current can be reduced.
[0029]
Thereafter, when the depression of the brake pedal 1 is loosened or further depressed as in the period t3 and after, a large dither amplitude is first set as shown in FIG. As shown in 3 (e), the dither current is superimposed again on the instruction current. FIG. 4B shows the relationship between the command current and the braking torque at this moment (period t3). By superposing the dither current on the command current as shown in FIG. As indicated by the middle arrow, the command current and the braking torque return to the proportional relationship (the relationship of line A).
[0030]
Then, the command current is calculated according to the depression state of the brake pedal 1, and the command current is increased or decreased as shown by the dotted line in FIG. 3C, and the braking force is increased or decreased accordingly. FIG. 4C shows the relationship between the command current and the braking torque after the period t3. As shown in this figure, the relationship between the command current and the braking torque returns to a relationship having no hysteresis, and based on this relationship, the braking torque changes as the command current changes.
[0031]
As described above, when the depression of the brake pedal 1 is maintained, the superposition of the dither current is stopped and the instruction current is reduced, whereby the instruction current can be reduced and the current consumption can be reduced. Is possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a brake device to which a first embodiment of the present invention is applied.
2 is a flowchart related to setting of an output current processed by the brake device shown in FIG. 1. FIG.
3 is a timing chart of pedal depression force, dither amplitude, instruction current, braking force, and output current (consumption current) in the brake device shown in FIG. 1. FIG.
4 is a diagram for explaining a relationship between an instruction current and a braking torque of the brake device shown in FIG. 1; FIG.
FIG. 5 is a diagram illustrating a relationship between an instruction current and a braking torque in a conventional brake device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Brake pedal, 2 ... Treading force sensor, 3 ... ECU, 4-7 ... Wheel,
8 to 11: Brake drive actuators.

Claims (2)

A dither current is superimposed on an instruction current determined according to depression of the brake pedal (1), and a current obtained by superimposing the dither current on the instruction current is passed as an output current to the brake driving actuators (8 to 11); In the vehicle brake device configured to generate a braking force by driving the brake driving actuator,
A line (A) indicating the relationship between the command current and the braking torque on which the dither current is superimposed is a line having a hysteresis indicating the relationship between the command current and the braking torque when the dither current is not superimposed ( B), an ascending line indicating the relationship between the command current and the braking torque when the command current is gradually increased, and a descending line indicating the relationship between the command current and the braking torque when the command current is gradually decreased. Is set between
In the state where the depression of the brake pedal is maintained, the superposition of the dither current is stopped, and the instruction current is lowered than when the depression of the brake pedal starts to be maintained. vehicle brake device comprising a score flow a current to the brake driving actuator as the output current. If there is a change in the depression of the brake pedal from the state where the depression is maintained, the reduced instruction current is returned to the instruction current when the depression of the brake pedal starts to be maintained, and the superposition of the dither current is again performed. A vehicular brake device that starts and flows a current obtained by superimposing a dither current on the indicated current as an output current to the brake driving actuator.

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