CN111065557B

CN111065557B - Brake control device

Info

Publication number: CN111065557B
Application number: CN201880055210.7A
Authority: CN
Inventors: 石田康人; 西胁邦博; 小林达史; 浅野智孝; 葛谷贤; 山本贵之
Original assignee: Advics Co Ltd
Current assignee: Advics Co Ltd
Priority date: 2017-09-05
Filing date: 2018-09-05
Publication date: 2022-04-05
Anticipated expiration: 2038-09-05
Also published as: CN111065557A; WO2019049868A1

Abstract

The brake control device according to the embodiment controls, in a coordinated manner, an upstream mechanism that increases or decreases the hydraulic pressure of the brake fluid in the master cylinder and a downstream mechanism that is connected to the upstream mechanism via a hydraulic line, increases or decreases the hydraulic pressure output from the upstream mechanism, and supplies the increased or decreased hydraulic pressure to the wheel cylinder, for example, based on a target wheel pressure that is a target value of the hydraulic pressure in the wheel cylinder. In the event of a hydraulic pressure fluctuation, the brake control device quickly eliminates the hydraulic pressure fluctuation by switching the control of the downstream mechanism from the FB control based on the detected hydraulic pressure detected by the hydraulic pressure sensor to the FF control based on the upstream target hydraulic pressure, thereby eliminating mutual interference of the controls of the upstream and downstream mechanisms.

Description

Brake control device

Technical Field

The present invention relates to a brake control device.

Background

Conventionally, as a brake control device for a vehicle such as a passenger vehicle, there is a brake control device that performs coordinated control of an upstream mechanism that increases and decreases a hydraulic pressure of a brake fluid in a master cylinder based on a target wheel pressure that is a target value of the hydraulic pressure in the wheel cylinder, and a downstream mechanism that is connected to the upstream mechanism via a hydraulic pressure line, increases and decreases the hydraulic pressure output from the upstream mechanism, and supplies the increased hydraulic pressure to the wheel cylinder.

In such a brake control device, the upstream mechanism is feedback-controlled so that the detected hydraulic pressure of the brake fluid in the upstream mechanism becomes the upstream target hydraulic pressure, and the downstream mechanism is feedback-controlled so that the detected hydraulic pressure of the brake fluid in the downstream mechanism becomes the target wheel pressure.

Patent document 1: japanese patent laid-open publication No. 2016-2977

In the conventional technique as described above, feedback control is performed in parallel and independently for both the upstream mechanism and the downstream mechanism, and therefore control may interfere with each other. Specifically, there is a phenomenon in which the inflow and outflow of the brake fluid are repeated between the upstream mechanism and the downstream mechanism for the purpose of adjusting the fluid pressure, and a fluctuation in the fluid pressure occurs in which the fluid pressure of the brake fluid is repeatedly increased and decreased in both the upstream mechanism and the downstream mechanism.

Disclosure of Invention

Accordingly, one of the problems to be solved by the present invention is to provide a brake control device capable of quickly eliminating a hydraulic pressure fluctuation even if the hydraulic pressure fluctuation occurs.

The present invention is a brake control device that coordinately controls an upstream mechanism that increases or decreases a hydraulic pressure of a brake fluid in a master cylinder and a downstream mechanism that is connected to the upstream mechanism via a hydraulic pressure line, increases or decreases a hydraulic pressure output from the upstream mechanism, and supplies the increased or decreased hydraulic pressure to a wheel cylinder, based on a target wheel pressure that is a target value of the hydraulic pressure in the wheel cylinder, for example. The brake control device is provided with: an upstream mechanism control unit that feedback-controls the upstream mechanism so that a detected hydraulic pressure detected by a hydraulic pressure sensor that detects a hydraulic pressure of the hydraulic line becomes an upstream target hydraulic pressure; a determination section that determines whether or not a hydraulic pressure fluctuation is occurring based on the detected hydraulic pressure detected by the hydraulic pressure sensor; and a control unit that controls the downstream mechanism based on the upstream target hydraulic pressure and the target wheel pressure when the determination unit determines that the hydraulic pressure fluctuation is occurring. Thus, when the hydraulic pressure fluctuation is occurring, by controlling the downstream mechanism based on the upstream target hydraulic pressure instead of the detected hydraulic pressure detected by the hydraulic pressure sensor, it is possible to eliminate mutual interference of the control of the upstream mechanism and the downstream mechanism, and quickly eliminate the hydraulic pressure fluctuation.

Drawings

Fig. 1 is a partially sectional explanatory view showing a structure of a vehicle brake device according to a first embodiment.

Fig. 2 is a flowchart showing a process in the downstream mechanism control unit according to the first embodiment.

Fig. 3 is a time chart showing changes over time in the hydraulic pressure, the hydraulic pressure fluctuation determination result, and the downstream mechanism control in the first embodiment.

Fig. 4 is a flowchart showing a process in the downstream mechanism control unit according to the second embodiment.

Fig. 5 is a time chart showing the behavior of the hydraulic pressure, the estimated result of the occurrence of hydraulic pressure fluctuations, the result of the determination of the difference between the actual M/C pressure and the target M/C pressure, and the temporal change in the downstream mechanism control in the second embodiment.

Detailed Description

Hereinafter, embodiments (first embodiment and second embodiment) of the present invention will be described with reference to the drawings. The configurations of the embodiments described below, and the operations and results (effects) of the configurations are merely examples, and the present invention is not limited to the following descriptions. The vehicle brake device is provided in, for example, a four-wheeled ordinary vehicle (such as a passenger car). In the following, a solenoid valve is a valve that can be electrically switched between an open state and a closed state.

(first embodiment)

First, a first embodiment will be explained. Fig. 1 is a partially sectional explanatory view showing a structure of a vehicle brake device according to a first embodiment. As shown in fig. 1, the vehicle brake device according to the first embodiment includes a brake pedal 1, a booster case 10, a hydraulic pressure generating device 2, a booster device 3, wheel cylinders 4, a hydraulic pressure Control device 5, a brake ECU (Electronic Control Unit) 6, a hydraulic pressure source 7, an electromagnetic valve 81, a reservoir 82, various sensors 91 to 93 communicating with a brake ECU6, and a hybrid ECU 9.

The hydraulic pressure generating device 2 includes a master cylinder 20, a first master piston 21, a second master piston 22, a return spring 23, and a reservoir X. In the following description, the direction in which the first and

second master pistons

21 and 22 are driven by depression of the brake pedal 1 (leftward in fig. 1) is referred to as the "forward direction", and the opposite direction (rightward in fig. 1) is referred to as the "backward direction". The master cylinder 20 is connected to the forward-side end portion of the booster housing 10. The master cylinder 20 is the same as a known tandem master cylinder, and detailed description thereof is omitted.

In the master cylinder 20, a "first master chamber 2a 1" is formed (divided) by an inner peripheral surface of the master cylinder 20, a forward side portion of the first master piston 21, and a backward side portion of the second master piston 22. Similarly, in the master cylinder 20, a "second master chamber 2a 2" is formed (divided) by the inner peripheral surface of the master cylinder 20 and the forward side portion of the second master piston 22. The hydraulic pressure generating device 2 slides relative to the master cylinder 20 by the

master pistons

21 and 22, and generates hydraulic pressure in the first master chamber 2a1 and the second master chamber 2a 2. Hereinafter, first main chamber 2A1 and second main chamber 2A2 will be referred to as main chamber 2A.

The

master pistons

21 and 22 are formed in a bottomed cylindrical shape having an opening on the forward side, and are biased in the backward direction by a return spring 23. Here, the first master piston 21 is formed with a rear end portion 21a extending in a backward direction from a backward side end portion thereof. A recess recessed toward the forward side is formed at the backward side end of the rear end 21 a. The reservoir X is connected to the

ports

20a, 20b of the master cylinder 20. With the

master pistons

21, 22 in the initial position, the accumulator X communicates with the master chamber 2A.

The hydraulic pressure source 7 includes a pump 7a connected to the reservoir X, a motor 7b for driving the pump 7a, an accumulator 7c, and a pressure sensor 7 d. The hydraulic pressure source 7 turns ON (ON) and OFF (OFF) the motor 7b based ON the pressure detected by the pressure sensor 7d, and maintains the hydraulic pressure stored in the accumulator 7c within predetermined upper and lower limit values.

The booster 3 is disposed in the supercharger housing 10, and includes an input rod 31, an output member 32, and a pressure adjusting unit 33. The booster 3 is a device that supplies hydraulic pressure from the hydraulic pressure source 7 into the assist chamber 3A in accordance with the operation of the brake pedal 1. The configuration including the supercharger case 10 and the hydraulic pressure source 7 may be referred to as a booster device 3.

The input rod 31 is connected to the brake pedal 1 at a rear-side end portion, and moves forward and backward in accordance with an operation amount (operation force) of the brake pedal 1. The output member 32 is disposed at an advancing-side end of the reaction force imparting member Y described later, and advances in accordance with the advance of the booster piston 331 described later.

The pressure adjusting unit 33 includes a pressure-increasing piston 331 and a spool 332. The booster piston 331 is formed in a substantially cylindrical shape, and accommodates therein the input rod 31, the spool 332, and the reaction force imparting member Y. The booster piston 331 defines an assist chamber 3A on the retreating side in the booster housing 10. In other words, on the retreating side of the booster piston 331, the assist chamber 3A is formed (divided) by the booster piston 331 and the inner peripheral surface of the booster housing 10.

The pressurizing piston 331 is provided with

passages

331a, 331b, and 331 c. The passage 331a is a passage that communicates the hydraulic pressure source 7 and the inside of the booster piston 331. The passage 331b is a passage that communicates the assist chamber 3A and the interior of the booster piston 331. The passage 331c is a passage that communicates the reservoir X and the interior of the pressurizing piston 331.

The spool valve 332 has

large diameter portions

332a and 332b having a larger diameter than the input rod 31, and the passages 331a to 331c are opened and closed by sliding the relative position of the pressure-intensifying piston 331 with respect to the

large diameter portions

332a and 332b back and forth. The spool 332 is connected to the input rod 31 and slides in accordance with the forward and backward movement of the input rod 31. The booster piston 331 is formed with a bottomed large diameter hole 331d that opens on the end surface on the forward side, and the reaction force imparting member Y is disposed in the large diameter hole 331 d. The small-diameter portion 332c formed at the forward end of the spool 332 slidably penetrates the bottom of the large-diameter hole 331d and abuts against the reaction force imparting member Y.

In the pressure adjusting unit 33, the brake pedal 1 is stepped on, the input rod 31 moves forward relative to the booster piston 331, and when the large diameter portion 332a moves forward by a predetermined amount, the passage 331a is opened, and the hydraulic pressure source 7 communicates with the assist chamber 3A. Thereby, the high-pressure brake fluid flows into the auxiliary chamber 3A. The pressure regulating unit 33 supplies a high-pressure hydraulic pressure to the assist chamber 3A in accordance with the operation of the brake pedal 1. When the assist chamber 3A becomes high pressure, the booster piston 331 moves forward, and the output member 32 moves forward.

The output member 32 is coupled to the first master piston 21 on the forward side. The forward end of the output member 32 is disposed in the recess of the rear end 21 a. The large diameter portion 32a formed on the retreating side of the output member 32 is slidably fitted into a large diameter hole 331d opened in the advancing side end surface of the booster piston 331, and abuts against the reaction force imparting member Y. In a state where the input rod 31 and the spool 332 are pushed back to the final retracted position by the return spring 333, the

passages

331b and 331c are opened, and the assist chamber 3A communicates with the reservoir X. The reaction force imparting member Y is a known member (e.g., a reaction disc) formed of a rubber disc, and generates a reaction force according to a braking operation amount.

The hydraulic control device 5 includes a valve device 51, a pressure increasing valve 52, a pressure reducing valve 53, a pump 54, a motor 55, and an accumulator 56. The valve device 51 is a normally open solenoid valve, and is connected to a pipe 511 connected to the main chamber 2A. The valve device 51 is an electromagnetic valve that can be controlled to a communicating state (non-energized state) and a differential pressure state, and the differential pressure state between the wheel pressure and the line pressure changes according to the current value of the current flowing through its solenoid in the driving state of the pump 54. The larger the current value, the larger the differential pressure amount. In this manner, the valve device 51 is a valve that controls the flow of the brake fluid between the hydraulic pressure generation device 2 and the wheel cylinder 4.

The pressure increase valve 52 is a normally open electromagnetic valve whose upstream side (main chamber 2A side) is connected to the valve device 51 and the pump 54 via a pipe 521, and whose downstream side (wheel cylinder 4 side) is connected to the wheel cylinder 4 via a pipe 522. In other words, the brake fluid from the master chamber 2A is supplied to the wheel cylinders 4 via the valve device 51 and the pressure increasing valve 52. The pressure increasing valve 52 is a two-position valve capable of controlling the on/off state. The pressure increasing valve 52 is put into a communication state at the time of a normal braking operation. Further, the pressure increasing valve 52 and the valve device 51 are provided with safety valves Z in parallel.

The pressure reducing valve 53 is a normally closed solenoid valve having one end connected to the pipe 522 and the other end connected to the accumulator 56 and the pump 54. The pressure reducing valve 53 is a two-position valve capable of controlling the communication/shutoff state. The pressure reducing valve 53 is in a shut-off state during a normal braking operation.

The pump 54 has a suction side connected to the accumulator 56 and the pressure reducing valve 53, and a discharge side connected to the pipe 521 (downstream side of the valve device 51 and upstream side of the pressure increasing valve 52). The pump 54 is driven by a motor 55. The motor 55 is on/off controlled by a brake ECU 6. That is, the brake ECU6 drives the motor 55 to operate the pump 54. The pump 54 discharges the brake fluid on the side of the hydraulic pressure generation device 2 with respect to the valve device 51 to the side of the wheel cylinder 4 with respect to the valve device 51. The accumulator 56 is connected to the main chamber 2A via a pipe 561, and is connected to the pump 54 and the pressure reducing valve 53 via a pipe 562.

The control of the hydraulic control device 5 may be performed by a known method. To explain this simply, the hydraulic pressure control device 5 controls the wheel pressure to a hydraulic pressure higher than the master pressure by discharging the brake fluid on the master cylinder 20 side of the valve device 51 to the wheel cylinder 4 side of the valve device 51 by the pump 54 after controlling the flow of the brake fluid between the master cylinder 20 and the wheel cylinder 4 by the valve device 51. The hydraulic control device 5 releases the flow of the brake fluid between the master cylinder 20 and the wheel cylinder 4 by the valve device 51, thereby controlling the wheel pressure to the same hydraulic pressure as the main compaction quality.

In the hybrid vehicle, the braking force is the sum of a hydraulic braking force caused by a wheel pressure obtained by adding a control hydraulic pressure to a line pressure and a regenerative braking force of a regenerative brake of a motor (not shown). Therefore, when the brake pedal 1 is operated, the brake ECU6 calculates a target braking force (all braking forces required) corresponding to the brake operation amount, calculates a control braking force obtained by subtracting the base braking force and the regenerative braking force received from the hybrid ECU9 from the target braking force, and controls the hydraulic control device 5 to generate a control hydraulic pressure corresponding to the control braking force.

For example, when the brake pedal 1 is stepped on, a base braking force and a regenerative braking force are generated by the master pressure. Further, when only the base braking force and the regenerative braking force are sufficient for the target braking force and the braking force is insufficient, the hydraulic pressure control device 5 generates the control hydraulic pressure by narrowing the flow path by the valve device 51 and discharging the brake fluid by the pump 54. At this time, the wheel pressure is controlled in accordance with an increase or decrease in the regenerative braking force in order to maintain the target braking force (deceleration) corresponding to the brake operation amount (stroke). The brake ECU6 controls the wheel pressure by throttling of the valve device 51.

The solenoid valve 81 is a normally closed linear valve provided in a pipe 83 to connect a port 10a provided in a wall portion that partitions the auxiliary chamber 3A of the supercharger housing 10 and the accumulator 82. In other words, the solenoid valve 81 is a linear valve that is disposed in a flow path connecting the assist chamber 3A and the reservoir 82, and that blocks communication between the assist chamber 3A and the reservoir 82. Opening and closing of the electromagnetic valve 81 is controlled by the brake ECU 6. Further, the reservoir 82 may be replaced with the reservoir X. The solenoid valve 81 is a linear valve whose opening degree can be adjusted, but may be a valve device whose opening and closing can be controlled.

The stroke sensor 91 transmits the operation amount (stroke information) of the brake pedal 1 to the brake ECU 6. The pressure sensors 92 provided to the wheel cylinders 4 transmit wheel pressure information to the brake ECU 6. The pressure sensor 93 (hydraulic pressure sensor) provided in the pipe 511 transmits the line pressure information to the brake ECU 6. The hybrid ECU9 sends the regenerative braking force information to the brake ECU 6.

Hereinafter, each mechanism for increasing or decreasing the hydraulic pressure of the brake fluid in the master cylinder 20 is referred to as an upstream mechanism. Each mechanism connected to the upstream mechanism via a hydraulic line (e.g., pipe 511) to increase or decrease the hydraulic pressure output from the upstream mechanism and supply the increased hydraulic pressure to the wheel cylinder 4 is referred to as a downstream mechanism.

The brake ECU6 is a brake control device that coordinately controls the upstream mechanism and the downstream mechanism based on a target wheel pressure that is a target value of the hydraulic pressure in the wheel cylinder 4. The brake ECU6 includes hardware similar to that of a general computer such as a processor and a memory, for example. Brake ECU6 and hybrid ECU9 transmit and receive information by CAN (Controller Area Network) communication.

The brake ECU6 includes an upstream mechanism control unit 61 and a downstream mechanism control unit 62. In fig. 1, the upstream mechanism control unit 61 and the downstream mechanism control unit 62 are physically implemented in one brake ECU6, but the upstream mechanism control unit 61 and the downstream mechanism control unit 62 may be physically implemented as separate ECUs. In this case, the upstream mechanism control unit 61 and the downstream mechanism control unit 62 transmit and receive information by CAN communication.

The upstream mechanism control unit 61 feedback-controls (hereinafter referred to as FB control) the upstream mechanism so that the detected hydraulic pressure detected by a pressure sensor 93 (hydraulic pressure sensor) that detects the hydraulic pressure of the hydraulic line becomes the upstream target hydraulic pressure calculated from the operation amount of the brake pedal 1.

The downstream mechanism control unit 62 controls the downstream mechanism so that the detected hydraulic pressure in the wheel cylinder 4 detected by the pressure sensor 92 becomes the target wheel pressure calculated from the operation amount of the brake pedal 1. The downstream mechanism control unit 62 includes, as a functional configuration, an acquisition unit 621, a determination unit 622, and a control unit 623.

The acquisition unit 621 acquires the detection hydraulic pressure detected by the pressure sensor 93 and the detection hydraulic pressure detected by the pressure sensor 92.

The determination section 622 determines whether or not the hydraulic pressure fluctuation is occurring based on the detected hydraulic pressure detected by the pressure sensor 93 (hydraulic pressure sensor). The determination unit 622 determines that the hydraulic pressure fluctuation is occurring when, for example, an increase or decrease in the detected hydraulic pressure detected by the pressure sensor 93 (hydraulic pressure sensor) occurs a predetermined number of times or more within a predetermined time.

When the determination unit 622 determines that the hydraulic pressure fluctuation is not generated, the control unit 623 controls the downstream mechanism so that the detected hydraulic pressure detected by the pressure sensor 92 becomes the target wheel pressure, based on the detected hydraulic pressure detected by the pressure sensor 93 (hydraulic pressure sensor), the detected hydraulic pressure detected by the pressure sensor 92, and the target wheel pressure FB.

When the determination unit 622 determines that the hydraulic pressure fluctuation is occurring, the control unit 623 feedback-controls (hereinafter, FF control) the downstream mechanism based on the upstream target hydraulic pressure, the detected hydraulic pressure detected by the pressure sensor 92, and the target wheel pressure.

Therefore, until the determination unit 622 determines that the hydraulic pressure fluctuation is occurring, both the upstream mechanism control unit 61 and the downstream mechanism control unit 62 execute the FB control in parallel and independently, and therefore, there is a case where control interference occurs. In other words, there is a case where the inflow and outflow of the brake fluid are repeated between the upstream mechanism and the downstream mechanism for the purpose of adjusting the fluid pressure, and a fluctuation in the fluid pressure is generated in which the fluid pressure of the brake fluid is repeatedly increased and decreased in both the upstream mechanism and the downstream mechanism. More specifically, for example, there is a case where, when the upstream mechanism discharges the brake fluid to the downstream mechanism for the fluid pressure adjustment, the operation of discharging the brake fluid to the upstream mechanism for the fluid pressure adjustment by the downstream mechanism that receives the brake fluid and changes the fluid pressure is repeated a plurality of times.

Therefore, in the first embodiment, in the case where the hydraulic pressure fluctuation is generated, the mutual interference of the control of the upstream mechanism and the downstream mechanism is eliminated and the hydraulic pressure fluctuation is promptly eliminated by switching the control of the downstream mechanism from the FB control based on the detected hydraulic pressure detected by the pressure sensor 93 to the FF control based on the upstream target hydraulic pressure.

Next, the processing in the downstream mechanism control unit 62 according to the first embodiment will be described with reference to fig. 2. Fig. 2 is a flowchart showing a process in the downstream mechanism control unit 62 according to the first embodiment. Here, as a premise, the brake pedal 1 is depressed at least at the start of the processing of the flowchart. The acquisition unit 621 of the downstream mechanism control unit 62 of the brake ECU6 acquires the detected hydraulic pressure detected by the pressure sensor 93 and the detected hydraulic pressure detected by the pressure sensor 92 at any time. At the start of the flowchart processing, the upstream mechanism control unit 61 and the downstream mechanism control unit 62 both execute the above FB control in parallel and independently.

In step S1, the determination unit 622 determines whether or not a hydraulic pressure fluctuation is occurring based on the detected hydraulic pressure detected by the pressure sensor 93 acquired by the acquisition unit 621, and proceeds to step S2 in the case of yes, and returns to step S1 in the case of no.

In step S2, the control unit 623 switches the control of the downstream mechanism from FB control to FF control.

Next, in step S3, the determination unit 622 determines whether or not a hydraulic pressure fluctuation is occurring based on the detected hydraulic pressure detected by the pressure sensor 93 acquired by the acquisition unit 621, and if yes, it proceeds to step S4, and if no, it proceeds to step S8.

In step S8, the control unit 623 returns the control of the downstream mechanism from the FF control to the FB control, and the process ends.

In step S4, the control unit 623 determines whether or not the residual pressure of the accumulator 7c is lower than a predetermined value, and if yes, the process proceeds to step S8, and if no, the process proceeds to step S5. When the residual pressure of the accumulator 7c is lower than the predetermined value (yes in step S4), the flow proceeds to step S8, and the control of the downstream mechanism is returned from the FF control based on the upstream target hydraulic pressure to the FB control based on the detection hydraulic pressure detected by the pressure sensor 93 because the reliability of the upstream target hydraulic pressure is reduced.

In step S5, the control unit 623 determines whether or not the upstream pressure increasing valve (not shown in the upstream mechanism) is malfunctioning, and proceeds to step S8 in the case of yes, and proceeds to step S6 in the case of no. When the upstream pressure increasing valve fails (yes in step S5), the flow proceeds to step S8, and the control of the downstream mechanism is returned from FF control based on the upstream target hydraulic pressure to FB control based on the detected hydraulic pressure by the pressure sensor 93, because the reliability of the upstream target hydraulic pressure is reduced.

Step S6 is premised on the upstream mechanism control unit 61 and the downstream mechanism control unit 62 being physically realized as separate ECUs, and performing transmission and reception of information by CAN communication, and the downstream mechanism control unit 62 receiving the upstream target hydraulic pressure from the upstream mechanism control unit 61 as needed. In step S6, the control unit 623 determines whether CAN communication is impossible, and if yes, the process proceeds to step S8, and if no, the process proceeds to step S7. When the CAN communication is not possible (yes in step S6), the flow proceeds to step S8, and the control of the downstream mechanism is returned from the FF control based on the upstream target hydraulic pressure to the FB control based on the hydraulic pressure detected by the pressure sensor 93, in order to avoid control instability due to the downstream mechanism control unit 62 not receiving the upstream target hydraulic pressure from the upstream mechanism control unit 61.

In step S7, the control unit 623 determines whether the upstream pressure (the detection hydraulic pressure detected by the pressure sensor 93) is zero, and if yes, the routine proceeds to step S8, and if no, the routine proceeds to step S3. When the upstream pressure is zero (yes in step S7), the flow proceeds to step S8, and the control of the downstream mechanism is returned from the FF control based on the upstream target hydraulic pressure to the FB control in which the detected hydraulic pressure detected by the pressure sensor 93 is returned to the FB control in which the control is not stabilized by the FF control based on the upstream target hydraulic pressure when the upstream pressure is zero.

The only necessary processing in steps S3 to S7 is step S3, and steps S4 to S7 are arbitrary processing.

Next, the temporal changes in the hydraulic pressure, the hydraulic pressure fluctuation determination result, and the downstream mechanism control in the first embodiment will be described with reference to fig. 3. Fig. 3 is a time chart showing changes over time in the hydraulic pressure, the hydraulic pressure fluctuation determination result, and the downstream mechanism control in the first embodiment. The target M/C pressure (upstream target hydraulic pressure) is not necessarily constant (does not change with time) in practice, but is constant here for the sake of simplicity of explanation and illustration.

In fig. 3, the actual M/C pressure (the detected hydraulic pressure detected by the pressure sensor 93) repeatedly increases and decreases from time t0 to time t1, and the determination unit 622 determines that a hydraulic pressure surge is occurring (off → on) at time t 1.

In this way, the control portion 623 switches the control of the downstream mechanism from FB control based on the detected hydraulic pressure detected by the pressure sensor 93 to FF control based on the upstream target hydraulic pressure. As a result, the increase and decrease in the actual M/C pressure subsides, and the determination unit 622 determines that no hydraulic pressure fluctuation has occurred (on → off) at time t 2.

In this way, the control portion 623 returns the control of the downstream mechanism from the FF control based on the upstream target hydraulic pressure to the FB control based on the detected hydraulic pressure detected by the pressure sensor 93. Since the hydraulic pressure fluctuation subsides at the time t2, there is a low possibility that the hydraulic pressure fluctuation will occur again immediately after the time t2 even if the downstream mechanism returns to the FB control.

As described above, according to the brake control device (brake ECU6) of the first embodiment, when the hydraulic pressure fluctuation is occurring, the downstream mechanism is controlled based on the upstream target hydraulic pressure instead of the detected hydraulic pressure detected by the pressure sensor 93, and thus it is possible to eliminate the mutual interference between the control of the upstream mechanism and the downstream mechanism and quickly eliminate the hydraulic pressure fluctuation. Therefore, deterioration of braking feeling and control instability due to the hydraulic pressure fluctuation can be suppressed.

Further, by determining that the hydraulic pressure fluctuation is occurring when the increase or decrease in the detected hydraulic pressure detected by the pressure sensor 93 occurs a predetermined number of times or more within a predetermined time, the occurrence of the hydraulic pressure fluctuation can be accurately determined.

Further, when the hydraulic pressure fluctuation is not generated, the detected hydraulic pressure detected by the pressure sensor 92 can be brought closer to the target wheel pressure earlier by FB controlling the downstream mechanism based on the detected hydraulic pressure detected by the pressure sensor 93.

(second embodiment)

Next, a second embodiment will be explained. The same matters as in the first embodiment will be appropriately omitted from redundant description. The control content by the brake ECU6 of the second embodiment is often applied to a case where the pressure is applied by the upstream mechanism, and may be any of a parking time, a traveling time (light stepping), and a traveling time (advanced stepping).

In the first embodiment, the condition for switching the control of the downstream mechanism from the FB control to the FF control is set to determine that a hydraulic pressure fluctuation has occurred based on the detected hydraulic pressure detected by the pressure sensor 93 (hydraulic pressure sensor). Instead, the condition may be such that occurrence of hydraulic pressure fluctuation is estimated. In other words, the estimation of the occurrence of the hydraulic pressure fluctuation is a case where a condition that the probability of occurrence of the hydraulic pressure fluctuation is considered to be large is satisfied, and for example, a case where the upstream pressure (the detected hydraulic pressure detected by the pressure sensor 93) is generated and the hydraulic pressure is held by the downstream mechanism, or a case where the rotation speed of the motor 55 of the downstream mechanism is equal to or more than a predetermined amount, or the like is performed. If the condition is changed in this manner, the switching can be performed earlier than in the case where the switching is performed after the actual occurrence of the hydraulic pressure fluctuation is determined, and the influence due to the occurrence of the hydraulic pressure fluctuation can be further reduced.

However, generally, there is a time interval between the rise of the target M/C voltage and the rise of the actual M/C voltage. For example, when the target M/C pressure is significantly higher than the actual M/C pressure, such as at the start of hydraulic pressure adjustment by an upstream mechanism, if switching is made from FB control using the actual M/C pressure to FF control using the target M/C pressure, the rise of the wheel pressure is delayed, and the brake force may be delayed. Therefore, in the second embodiment, a method of estimating the occurrence of the hydraulic pressure fluctuation as the condition and suppressing the delay in the brake performance as described above will be described.

With reference to fig. 4, a process in the downstream mechanism control unit of the second embodiment will be described. Fig. 4 is a flowchart showing a process in the downstream mechanism control unit according to the second embodiment. The precondition is the same as in the case of fig. 2.

In step S11, the determination unit 622 determines whether or not occurrence of hydraulic pressure fluctuations is estimated, and proceeds to step S12 in the case of yes, and returns to step S11 in the case of no. The specific method of inference is as described above.

In step S12, the determination unit 622 determines whether or not the difference (response delay) between the actual M/C pressure and the target M/C pressure is equal to or greater than a predetermined threshold value (a value equal to or greater than 0 is set in advance; a predetermined allowable value), and if yes, the process proceeds to step S2, and if no, the process returns to step S12. Steps S2 to S8 are the same as in fig. 2.

Next, the estimation result of the occurrence of the hydraulic pressure and the hydraulic pressure fluctuation, the determination result of the difference between the actual M/C pressure and the target M/C pressure, and the temporal change in the downstream mechanism control in the second embodiment will be described with reference to fig. 5. Fig. 5 is a time chart showing the behavior of the hydraulic pressure, the estimated result of the occurrence of hydraulic pressure fluctuations, the result of the determination of the difference between the actual M/C pressure and the target M/C pressure, and the temporal change in the downstream mechanism control in the second embodiment.

In fig. 5, after time t10, the target M/C voltage increases from time t11 to time t14 and becomes constant after time t 14. In this case, the actual M/C pressure follows the target M/C pressure, but during the period from time t11 to time t16, the actual M/C pressure is smaller than the target M/C pressure.

The estimation result of the occurrence of the hydraulic pressure fluctuation by the determination unit 622 is off (estimated to be not occurring) from time t10 to time t13, on (estimated to be occurring) from time t13 to time t17, and off after time t 17.

The difference between the actual M/C pressure and the target M/C pressure determined by the determination unit 622 is off (no difference in significance) from time t10 to time t12, on (difference in significance) from time t12 to time t15, and on after time t 15.

In this way, in the processing of fig. 4, the time when "yes" is performed in step S11 is time t13, but the time when "yes" is performed in step S12 is time 15, so at the time of time t15, the FB control using the actual M/C voltage is switched to the FF control using the target M/C voltage. In other words, the downstream mechanism control is FB control from time t10 to time t15, FF control from time t15 to time t17, and FB control after time t 17.

As such, according to the brake control apparatus (brake ECU6) of the second embodiment, even if the occurrence of the hydraulic pressure fluctuation is inferred, the FB control is maintained in the case where the target M/C pressure is significantly higher than the actual M/C pressure, and thereafter, the FF control is switched to as close as the actual M/C pressure is at the target M/C pressure (to eliminate the conspicuousness difference). Thereby, the generation of the hydraulic pressure fluctuation can be suppressed earlier, and the delay in the brake effectiveness can also be suppressed.

While the embodiments of the present invention have been described above, the embodiments are merely examples and are not intended to limit the scope of the present invention. The above-described new embodiments can be implemented in various ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. The above-described embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the protection scope of the invention and the equivalent scope thereof.

For example, in each of the embodiments described above, in the case where a hydraulic pressure fluctuation is generated (including inference), the control of the downstream mechanism is switched from FB control based on the detected hydraulic pressure detected by the pressure sensor 93 to FF control based on the upstream target hydraulic pressure, but is not limited thereto. For example, instead of FF control based on the upstream target hydraulic pressure, control based on the smaller value of the upstream target hydraulic pressure and the detected hydraulic pressure detected by the pressure sensor 93, or control based on the average value of the upstream target hydraulic pressure and the detected hydraulic pressure detected by the pressure sensor 93 may be employed. In this way, it is possible to reduce the possibility of occurrence of a pressure increase delay due to not using the actual pressure (the detected hydraulic pressure detected by the pressure sensor 93) at all.

Claims

1. A brake control device that coordinately controls an upstream mechanism that increases or decreases a hydraulic pressure of a brake fluid in a master cylinder and a downstream mechanism that is connected to the upstream mechanism via a hydraulic line, increases or decreases a hydraulic pressure output from the upstream mechanism, and supplies the hydraulic pressure to a wheel cylinder, based on a target wheel pressure that is a target value of the hydraulic pressure in the wheel cylinder,

the brake control device includes:

an upstream mechanism control unit that feedback-controls the upstream mechanism so that a detected hydraulic pressure detected by a hydraulic pressure sensor that detects a hydraulic pressure of the hydraulic line becomes an upstream target hydraulic pressure;

a determination section that determines whether or not a hydraulic pressure fluctuation is occurring based on the detected hydraulic pressure detected by the hydraulic pressure sensor; and

and a control portion that controls the downstream mechanism based on the detected hydraulic pressure detected by the hydraulic pressure sensor and the target wheel pressure when it is determined by the determination portion that the hydraulic pressure fluctuation is not generated, and controls the downstream mechanism based on the upstream target hydraulic pressure and the target wheel pressure when it is determined by the determination portion that the hydraulic pressure fluctuation is being generated.

2. The brake control apparatus according to claim 1,

the determination unit determines that the hydraulic pressure fluctuation occurs when an increase or decrease in the detected hydraulic pressure detected by the hydraulic pressure sensor occurs a predetermined number of times or more within a predetermined time.

3. The brake control apparatus according to claim 1 or 2,

when the response delay of the detected hydraulic pressure detected by the hydraulic pressure sensor with respect to the upstream target hydraulic pressure is equal to or greater than a predetermined permissible value, the control unit controls the downstream mechanism based on the detected hydraulic pressure detected by the hydraulic pressure sensor and the target wheel pressure even when the determination unit determines that the hydraulic pressure is fluctuating.