JP2000344072A - Brake noise detecting method and brake noise preventing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect the generation of brake noise by detecting a unique waveform when brake noise is generated by two sensors, a vibration sensor and a brake torque sensor, and detecting the vibration generated in the brake itself according to the detected waveform. SOLUTION: A wheel speed sensor 9, a torque sensor 11 and a vibration sensor 12 are provided on each wheel, and the wheel speed, the variation of brake torque and the vibration of a caliper are detected and sent to an electronic control device 13. In a control flow, when the caliper vibration immediately after the control flow is strated is 1 G or more, and the brake torque change is 1500 kgfm/sec or more, it is decided that brake noise is generated. This brake noise preventing device is adapted to restrain the generation of brake noise by opening and closing a decay valve 5 to reduce the brake liquid pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for detecting a brake noise which can prevent creep groans (hereinafter referred to as "brake noise") generated during creep running in a vehicle equipped with a fluid automatic transmission. In particular, a brake that can reliably detect brake noise generated when the brake is actuated and operate the solenoid valve in the brake circuit in accordance with a predetermined algorithm to reduce or increase the brake pressure while reliably preventing the occurrence of brake noise The present invention relates to a noise prevention device.

[0002]

2. Description of the Related Art Conventionally, in order to stop the squeal of a disk brake, there has been known a vibration damping device which suppresses a brake vibration which is a cause of the squeal by an active method (Japanese Patent Laid-Open No. 9-21).
436). In this device, two vibration detecting means for detecting brake vibration from a pad are provided, and two vibrating means for applying vibration in a direction to cancel the brake vibration to the pad are provided. A vibration signal for canceling the brake vibration is generated based on the sum, and the two vibration means are vibrated by the signal to attenuate the brake vibration. By providing a plurality of vibration detecting means or vibrating means, the brake vibration in the large-sized disc brake is made smaller than ever, and the effect of suppressing squeal (brake noise) is enhanced.

[0003]

The cause of the above-mentioned brake squeal will be described in detail with reference to FIG.
In the figure, as the pedaling force decreases and the brake pressure decreases, the brake torque decreases and the drive torque balances with the brake force. In the vicinity (point A), the brake pad accumulates energy in the friction material of the brake pad of the disc brake device. Elastic deformation occurs in the friction material of
The change in brake torque at the time of starting increases. Here, the energy (part of the frictional force of the brake pad) stored by the elastic deformation of the friction material of the brake pad is released at a certain point (point B) due to the gradual decrease of the brake pressure, and the drive torque and the brake torque are reduced. The difference (F1) increases and an exciting force is generated on the brake pad. Then B
After the time of 1, B2, etc., the change in the brake torque at the time of starting again increases as shown by F2 and F3 in the figure, and each time the elastic deformation energy in the brake pad is released, the so-called brake pad and rotor This causes the stick-slip phenomenon. Such periodic fluctuations in force cause vibration around the brake or suspension, which causes brake noise.

Accordingly, an object of the present invention is to provide a brake noise detecting method capable of reliably detecting a brake noise generated during a brake operation based on a caliper vibration and a change amount of a brake torque, and to solve the above problems. I do. Further, the present invention provides a brake noise prevention device that can reliably prevent brake noise by controlling the amount of decrease or increase in brake pressure according to a predetermined algorithm after the brake noise is detected by the above-described brake noise detection method. And to solve the above problems.

According to the present invention, when a brake noise is generated in a state where the brake is operated while the vehicle is running, a unique waveform at the time of the occurrence of the brake noise is detected by using two sensors, a vibration sensor and a brake torque sensor. By adopting a method of detecting the vibration occurring in the brake itself based on this, it is possible to reliably detect the occurrence of the brake noise.
When brake noise actually occurs, the brake pressure is reduced or increased by opening and closing the solenoid valve according to a predetermined algorithm, thereby preventing the occurrence of brake noise.

[0006]

For this reason, the technical solution adopted by the present invention detects a brake torque and a caliper vibration when a brake is operated at a predetermined speed or less, and detects a change in the brake torque and the caliper vibration. This is a brake noise detection method characterized by the occurrence of brake noise at the above time.If the occurrence of brake noise is detected during the operation of the brake, the valve provided between the brake device and the reservoir is opened to reduce the brake pressure. A brake noise prevention device characterized in that when a brake noise occurrence is detected during a brake operation, a valve provided between the brake device and a pressure accumulation source is opened to increase the brake pressure. This is a characteristic brake noise prevention device.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a brake device according to a first embodiment used in the present brake noise detecting method, and FIG. It is a flowchart for the. In the brake device according to the present embodiment, a wheel speed sensor, a torque sensor, and a vibration sensor are provided for each wheel in a conventionally known brake device, and a brake noise is detected by a signal from these sensors.

In FIG. 1, 1 is a brake pedal as a brake operating member, 1a is a brake switch, 2 is a vacuum booster as a brake booster, 3 is a master cylinder (M / C), 4 is, for example, a rear wheel system. , A hold valve provided in a brake circuit for each wheel, 5 a decay valve in the same system, 6 and 6 left and right wheel cylinders (W / C), 7 a reservoir, 8 a pump, M a pump 8
, A wheel speed sensor for detecting wheel speed, 11 for a torque sensor attached to a caliper for detecting brake torque, 12 for a vibration sensor for detecting vibration of the caliper, and 13 for an electronic control unit. The hold valve 4 is a conventionally known normally-open two-position switching valve, and the decay valve 5 is a conventionally known normally-closed two-position switching valve. Opening / closing is controlled by the signal.

Further, the reservoir 7 has a function of allowing the brake fluid from the wheel cylinder 6 to flow when the decay valve 5 is opened. A piston 7b urged upward in the figure by a spring 7c is slidably disposed in a liquid-tight state in a cylinder 7a constituting the reservoir 7, and the piston 7b moves downward in the figure as it moves downward. A fluid chamber 7d that can store the brake fluid from the wheel cylinder 6 is formed in the cylinder 7a. The liquid chamber 7 d is connected to the pump 8 and the decay valve 5.

A wheel speed sensor 9, a torque sensor 11, and a vibration sensor 12 are provided for each wheel, and can detect wheel speeds, fluctuations in brake torque, and vibrations of the calipers, and send them to an electronic control unit 13. I have. Any type of vibration sensor can be used as the vibration sensor 12 as long as it can detect vibration at the time of occurrence of brake noise such as vibration of a brake device, brake fluid pressure, vehicle body, or suspension. In the drawing, the thick solid line represents the brake fluid circuit, and the thin solid line represents the electronic control unit 13 and the motor M for driving the pump, the brake switch 1a, the hold valve 4, the decay valve 5, the wheel speed sensor 9, the torque sensor 1
1. Signal path for electrically connecting the vibration sensor 12

In this brake device, the brake pedal 1
, The hydraulic pressure generated in the master cylinder 3 becomes
Wheel cylinder 6 via open hold valve 4
And the brakes operate. Also brake pedal 1
Is released, the brake fluid in the wheel cylinder 6 returns to the master cylinder 3 via the hold valve 4 and the brake is released. If the wheels tend to lock during the braking operation, antilock control is started in a known control mode, the hold valve 4 and the decay valve 5 are opened and closed, and the pump 8 is also operated to eliminate the locking tendency.

Next, a method of detecting brake noise when brake noise occurs in the brake device will be described with reference to a flowchart shown in FIG. As described above, the brake noise is generated when the vehicle is to be started by gradually releasing the brake pedal after the vehicle stops. For this reason, when the control of the brake noise detection is started in FIG. 2, the brake switch 1a is turned off in step S1.
N (the state where the brake pedal is operated)
When the brake switch is ON, the process proceeds to step S2, in which the vehicle speed V is fetched from the wheel speed sensor 9, and the vehicle speed V is equal to or less than the reference speed K (for example, 5 km / h) (V ≦ K).
Is determined. In this state, the vehicle is actually moving very slowly. If the vehicle speed V ≦ the reference speed K is satisfied in step S2, the process proceeds to step S3, and it is determined whether or not the grown flag is ON. Here, since the green flag is initialized at the start of the control flow and is in the OFF state, immediately after the start of the control, step S3 is determined to be NO.

If the glow flag is determined to be NO, the process proceeds to step S4, and it is determined whether or not the input value from the vibration sensor 12, that is, the caliper vibration is equal to or more than a predetermined value (for example, 1 G). When the caliper vibration is equal to or more than the predetermined value, the process proceeds to step S5, and it is determined whether the input value from the brake torque sensor, that is, the change in brake torque is equal to or more than a predetermined value (for example, 1500 kgfm / sec). In the case of, the process proceeds to step S6, where the grown flag is turned on, and the process returns to step S1 again. In this way, it is first determined that the brake noise is occurring. If a negative determination is made in steps S4 and S5, it is determined that no brake noise has occurred, and the process returns to step S1.

After returning to step S1 through step S6, YE is performed in steps S1, S2 and S3.
When the determination of S is made, the process proceeds to step S7, where the caliper vibration is set to a predetermined value (for example, 0.5 G).
It is determined whether or not: When the vibration of the caliper is not less than the predetermined value (for example, 0.5 G) in step S7, it is determined that the brake noise is occurring, and the process returns to step S1 to repeat the control flow. When the caliper vibration is equal to or less than the predetermined value, the process proceeds to step S8, and this time, the change in the brake torque is changed to the predetermined value (for example, 0.5 kgfm).
/ Sec) or less, and if not less than the predetermined value, it is determined that brake noise is still occurring and the process returns to step S1 to repeat this control flow. If the change in the brake torque is equal to or smaller than the predetermined value (for example, 0.5 kgfm / sec) in step S8, it is determined that the generation of the brake noise has been eliminated, the process proceeds to step S9, the grown flag is turned off, and the program ends. In this determination, the brake noise is such that the vibration of the caliper is equal to or less than a predetermined value (for example, 0.5 G) and the change in brake torque is a predetermined value (for example, 0.5 kgfm / sec).
c) In the following cases, it is determined that the brake noise has been eliminated and the green flag is turned off. If NO is determined in steps S1 and S2, it is determined that no brake noise has occurred, and the flow advances to step S9 to set the green flag to O.
The control flow is set to FF and the control flow is repeated from the beginning.

As described above, in this control flow, immediately after the control flow is started, the caliper vibration is 1 G or more, and the brake torque change is 1500 kgfm / s.
When ec or more, it is determined that brake noise has occurred, and thereafter the caliper vibration is 0.5G or less, and
Until the change in the brake torque becomes 0.5 kgfm / sec or less, it is determined that the brake noise continues to be generated, and the grown flag is kept ON to determine that the brake noise is being generated. Thus, the occurrence of brake noise is detected.

Next, a description will be given of a brake noise prevention device for preventing the occurrence of brake noise when it is determined that brake noise has occurred according to the above control flow. This brake noise prevention device opens and closes the decay valve 5 in the brake device shown in FIG.
The brake noise is reduced by reducing the brake fluid pressure.

Hereinafter, a control flow for suppressing the brake noise by opening and closing the decay valve while the brake noise is occurring to reduce the brake fluid pressure will be described.
The control for preventing the occurrence of the brake noise will be described with reference to FIG. 3. This control is a control for suppressing the brake noise by reducing the brake pressure for a certain time when it is determined that the brake noise is being generated. It is. When the control flow is started, in step S11, it is determined whether or not the grown flag is ON according to the above-described brake noise detection flow (see FIG. 2). Green flag ON
When the determination is made, the process proceeds to step S12, and it is determined whether or not the previous grown flag is OFF. And step S1
In step 2, when the previous grown flag is OFF, the process proceeds to step S13 to start cant start with CNT = 0, and proceeds to step S14 to open the decay valve 5.

Then, returning to step S11, while the brake noise is occurring, the grown flag is ON, so the process proceeds to step S12, and the previous time the grown flag is ON.
Therefore, the process proceeds to step S15 to count up (CNT = CNT + 1), and then proceeds to step S16 to determine whether the count CNT is greater than a predetermined value PT (PT <CNT). When it is determined in step S16 that the count CNT is smaller than PT, step S17 is skipped and the process returns to step S11. If it is determined in step S16 that the count CNT is larger than PT, the decay valve 5 is closed in step S17 (that is, if the count CNT becomes larger than PT while the green flag is ON, the reduction of the brake fluid pressure is stopped. Then, even if the green flag is ON thereafter, the brake fluid pressure is not reduced.) When it is determined in step S11 that the grown flag is not ON, that is, when it is determined that the brake noise has disappeared, the flow proceeds to step S18, the decay valve 5 is closed, and further the flow proceeds to step S19, where the count CNT is set to zero. And the control flow ends.

Subsequently, while the brake noise is occurring, the state in which the brake fluid pressure is reduced for a predetermined time and then the brake fluid pressure is maintained for a predetermined time is defined as one cycle, and this cycle is repeated to suppress the brake noise. The control flow of the embodiment will be described with reference to FIG. When the control flow is started, in step S21, it is determined whether or not the grown flag is ON according to the above-described brake noise detection flow (see FIG. 2). The green flag is O
If determined to be N, the process proceeds to step S22, and it is determined whether or not the previous grown flag is OFF. And when the previous grown flag is OFF, the process proceeds to step S23 and CN
A cant start is started with T = 0, and step S24 is started.
Then, the decay valve 5 is opened.

Then, returning to step S21, while the brake noise is generated, the grown flag is ON, so the flow proceeds to step S22. Since the previous grown flag is also ON, the flow proceeds to step S25 to count up ( CNT = CNT + 1), and then step S2
Proceeding to 6, it is determined whether or not the count CNT is larger than a predetermined value PT (PT <CNT). And step S2
If it is determined in step 6 that the count CNT is larger than PT, the decay valve 5 is closed (that is, the pressure reduction is stopped) in step S27. Then, in step S28, the count CNT
Is returned to step S21 until is larger than WT (that is, until the determination is YES), and the same flow is repeated. During this time, the brake fluid pressure is maintained. When it is determined in step S28 that the count CNT has become larger than WT (that is, the determination is YES), the count CNT is cleared to zero (CNT =
0), the decay valve 5 opens and the pressure reduction is started again.
After such control is repeated, when it is determined that the brake noise has been eliminated and the grown flag has been turned off in step S21, the process proceeds to step S31, the decay valve 5 is closed, and CNT = 0 in step S32.
And the control flow ends.

The grown flag O according to the above control flow
The relationship between N, OFF, decay valve open / close, count CNT and PT, and how the brake fluid pressure is reduced according to the control flow will be described with reference to FIG. In the figure, when the brake noise occurs, the green flag is turned ON. When the green flag turns on, the decay valve 5
Is opened to start reducing the brake fluid pressure.
The count is started and CNT starts increasing. And
When the count CNT reaches a predetermined value (PT), the decay valve 5 is closed, the reduction of the brake fluid pressure is stopped, and the brake fluid pressure at that time is maintained. After that, while the grown flag is ON, the count CNT is a predetermined value (WT).
Until the brake fluid pressure at that time is maintained. Then, when the count CNT reaches a predetermined value (WT), the count CNT becomes zero, the same control is repeated again, and the brake fluid pressure is reduced as shown in FIG. That is, in this flow, the cycle from the start of the count CNT to zero to a predetermined value (WT) is defined as one cycle, and the control of this one cycle is repeated while the grown flag is ON.

Next, a brake device according to a second embodiment for suppressing the occurrence of brake noise will be described.
In this brake device, brake noise is eliminated by increasing the brake fluid pressure. FIG. 6 is a configuration diagram of the brake device according to the second embodiment. In FIG. 6, 21 is a brake pedal as a brake operating member, 21a is a brake switch, 22 is a vacuum booster as a brake booster, 23 is a master cylinder (M / C), 24
Are switching valves provided in a brake circuit 35 for each wheel of the rear wheel system, and 26, 26 are left and right wheel cylinders (W
/ C), 27 is an accumulator, 28 is a pump, M is a motor for driving the pump 28, 29 is a wheel speed sensor for detecting wheel speed, 30 is a torque sensor attached to a caliper for detecting brake torque, 31 is A vibration sensor 32 detects the vibration of the caliper, and 32 is an electronic control unit. The switching valve 24 is connected to the master cylinder 23
And the flow path 33, and the accumulator 27 and the flow path 3
4 to switch the flow path by a signal output from the electronic control unit 32 in accordance with a flowchart for preventing brake noise. When the accumulator 27 falls below a predetermined hydraulic pressure, the pump 28
Is activated to maintain a predetermined hydraulic pressure.

The wheel speed sensor 29, the torque sensor 30,
The vibration sensor 31 is provided for each wheel, and detects a wheel speed, a variation in brake torque, and a vibration of a caliper, and can send the vibration to the electronic control device 32. Any type of vibration sensor can be used as the vibration sensor 31 as long as it can detect vibration at the time of occurrence of brake noise such as vibration of a brake device, brake fluid pressure, vehicle body, or suspension. In the drawing, a thick solid line indicates a brake fluid circuit, and a thin solid line indicates an electronic control unit 32, a motor M for driving a pump, a brake switch 21a, a switching valve 24,
Wheel speed sensor 29, torque sensor 30, vibration sensor 3
1 is a signal path for electrically connecting the signal path 1 to the signal path 1.

In this brake device, the brake pedal 2
When step 1 is depressed, the hydraulic pressure generated in the master cylinder 23 flows into the wheel cylinder 26 via the switching valve 24 to operate the brake. When the brake pedal 21 is released, the brake fluid in the wheel cylinder 26 returns to the master cylinder 23 via the switching valve 24, and the brake is released. Next, when the brake noise occurs in the brake device, the brake noise is detected by the above-described brake noise detection method shown in FIG. 2, and the switching valve 24 is controlled by the brake noise elimination control flow shown in FIG. To eliminate the occurrence of brake noise. Steps S14 and S1 in FIG.
7, the step S18, and the valves of step S24, step S27, step S30, and step S31 in FIG. In the case of this device,
The switching valve 24 is switched to eliminate the brake noise, and the hydraulic pressure from the accumulator 27 is supplied to the wheel cylinder to increase the brake hydraulic pressure. In the above example, the example of the brake device using the hydraulic pressure has been described. However, the present invention can be applied to the brake pressure control of the brake device operated by the air pressure.

[0025]

As described in detail above, according to the present invention,
When the brake noise is applied while the vehicle is running, when the brake noise occurs, a unique waveform at the time of the occurrence of the brake noise is detected by using two sensors, a vibration sensor and a brake torque sensor, and based on this, the brake itself is detected. Therefore, the occurrence of the brake noise can be reliably detected in order to detect the vibration that occurs. Also, when brake noise actually occurs, the solenoid valve is opened and closed according to a predetermined algorithm to control the brake fluid pressure to be reduced or increased, thereby preventing the occurrence of brake noise. Action and effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a brake device according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a brake noise detection method according to the present invention.

FIG. 3 is a flowchart for eliminating brake noise according to the present invention.

FIG. 4 is a flowchart relating to control different from FIG. 3 for eliminating brake noise according to the present invention.

FIG. 5 is a flowchart according to FIG. 4 showing a grown flag, a drive valve, a counted number, and a brake fluid pressure (reduced pressure).
FIG.

FIG. 6 is a configuration diagram of a brake device according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a cause of brake squeal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Brake pedal 2 Vacuum booster 3 Master cylinder 4 Hold valve 5 Decay valve 6 Wheel cylinder 7 Reservoir 8 Pump 9 Wheel speed sensor 11 Brake torque sensor 12 Vibration sensor 13 Electronic control unit

Claims (3)

[Claims] 1. A brake noise detecting method comprising: detecting a brake torque and caliper vibration when a brake is applied while traveling at a predetermined speed or less, and generating a brake noise when the brake torque vibration and the caliper vibration exceed a predetermined value. . 2. A brake noise prevention device, wherein when a brake noise occurrence is detected during a brake operation, a valve provided between a brake device and a reservoir is opened to reduce a brake pressure. 3. A brake noise prevention device, wherein when a brake noise occurrence is detected during a brake operation, a valve provided between a brake device and a pressure accumulation source is opened to increase a brake pressure.