JPH0891185A - Brake abnormal sound preventive device - Google Patents

Abstract

PURPOSE: To prevent a brake abnormal sound when a vehicle departs by a creep phenomenon by reducing brake oil pressure by a brake oil pressure control means on the basis of output of a vehicle departing condition detecting means and an abnormal sound generating area detecting means. CONSTITUTION: Brake operation is gradually released by a driver, and brake oil pressure P is reduced, and when this brake oil pressure reaches an abnormal sound generating area (Pa+ΔP), it is confirmed, and an automatic transmission is shifted to a gear position except first speed. Next, after whether or not a brake is completely released is confirmed, in order to obtain departing torque, the automatic transmission is shifted to first speed, and processing is completed. In this way, even when a device is constituted so that the automatic transmission is shifted to a gear position except first speed when the brake pressure P reaches the abnormal sound generating area, creep force of the automatic transmission when a vehicle departs at crawling speed is reduced, and compulsory force of a stick slip is reduced, and as a result, generation of an abnormal sound is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake noise suppressor applied to a vehicle equipped with a fluid type automatic transmission.

[0002]

2. Description of the Related Art Among brake devices for vehicles, for example, a disk brake device having a structure in which a disk rotor is sandwiched between a pair of pads and tightened for braking has a problem that a so-called "braking noise" is generated. . It is known that this "braking noise" is caused by stick-slip (self-excited vibration) between the disc rotor and the pad.

Therefore, the applicant of the present invention has already proposed a brake pad capable of preventing such "stick noise" by reducing stick-slip with the disc rotor (Japanese Patent Laid-Open No. 4-125326).

According to the improved brake pad,
By laminating the high temperature viscoelastic material and the low temperature viscoelastic material on the back surface of the back plate of the brake pad, it is possible to damp vibrations in a wide temperature range and prevent "brake noise" of the brake pad.

However, in order to prevent "abnormal noise" by improving the brake pad (friction material) as described above, the original performance of the brake, for example, other performances such as brake efficiency, abrasion resistance or fade resistance. New measures are needed to satisfy both. Further, for example, in order to improve the braking efficiency, it is preferable to use a friction material having a large friction coefficient, but on the other hand, such a friction material having a large friction coefficient tends to cause an abnormal noise, which causes an antinomy. In other words, the improvement of the brake pads alone is not a comprehensive solution, and measures for this have been eagerly awaited.

In particular, in a vehicle equipped with a fluid type (for example, torque converter) automatic transmission, a creep phenomenon occurs when the brake is released (when the brake hydraulic pressure is gradually reduced) at the time of starting. Stick-slip occurred on the brake (disk rotor and pad) due to the balance between the wheel rotation force and the brake friction force.
In this case, it is difficult to sufficiently prevent the generation of "brake noise" only by using the above-mentioned improved brake pad, and effective measures have been demanded.

[0007]

SUMMARY OF THE INVENTION In consideration of the above facts, the present invention prevents "brake noise" when a vehicle starts due to a creep phenomenon without affecting the original performance of the brake such as the braking efficiency. It is an object to obtain a brake noise prevention device that can be used.

[0008]

According to a first aspect of the present invention, there is provided a brake abnormal noise preventive device including a hydraulic automatic transmission and a brake hydraulic pressure control means for controlling brake hydraulic pressure according to a running state of a vehicle. And a vehicle start state detecting means for detecting a vehicle start caused by an output of the fluid automatic transmission when a brake is released from a stopped state of the vehicle, An abnormal sound generation area detection unit that detects an abnormal sound generation area of the brake in a starting state, and based on the outputs of the vehicle start state detection unit and the abnormal sound generation area detection unit, the brake hydraulic pressure control unit. The feature is that the brake hydraulic pressure is reduced.

A brake noise suppressor according to a second aspect of the present invention is a brake noise suppressor applied to a vehicle equipped with a hydraulic automatic transmission, wherein the brake is released from a stopped state of the vehicle, and A vehicle start state detecting means for detecting the start of the vehicle by the output of the fluid automatic transmission is provided, and the fluid automatic transmission is shifted to a gear position other than the first speed based on the output of the vehicle start state detecting means. , Is characterized.

[0010]

According to the brake noise preventing apparatus of the present invention, when the vehicle is released from the stopped state and the vehicle is started due to the creep phenomenon of the hydraulic automatic transmission, this is detected by the vehicle starting state detecting means, Further, the abnormal noise occurrence region of the brake in this starting state is detected by the abnormal noise occurrence region detecting means. When an abnormal noise generation region is detected when the vehicle starts, the brake hydraulic pressure control means reduces the brake hydraulic pressure.

The abnormal noise when the vehicle starts is generated in a region where the creep force of the hydraulic automatic transmission and the frictional force of the brake are balanced.

In this case, in the brake noise suppressor according to the first aspect, the brake hydraulic pressure is reduced when the abnormal noise generation region is detected as described above. In other words, the frictional force of the brake is promptly increased. In order to reduce and to quickly escape from the state that is in balance with the creep force of the hydraulic automatic transmission,
Abnormal noise generation time is shortened, and as a result, generation of abnormal noise is prevented.

According to another aspect of the present invention, when the vehicle is stopped and the brake is released and the vehicle is started due to the creep phenomenon of the hydraulic automatic transmission, this is detected by the vehicle start state detecting means. . When the starting state of the vehicle is detected, the hydraulic automatic transmission is shifted to a gear position other than the first speed.

Here, the abnormal noise when the vehicle starts is caused by stick-slip of the brake, and the compulsory force of the stick-slip (restraining force to be generated) depends on the creep force of the hydraulic automatic transmission. Increase or decrease.

In this case, in the brake noise suppressor according to the second aspect, when the starting state of the vehicle is detected as described above, the hydraulic automatic transmission shifts to a gear position other than the first gear, so in other words. For example, since the creep force of the fluid automatic transmission is reduced, the stick-slip force is reduced, and as a result, abnormal noise is prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first embodiment of the present invention will be described below with reference to FIGS.
An example will be described.

FIG. 2 shows the entire structure of the brake noise suppressor 10 according to the first embodiment.

The brake noise suppressor 10 includes a fluid type (for example, torque converter) automatic transmission 12, and an ABS (antilock brake system) actuator 16 (pump, reservoir, electromagnetic control valve) as brake hydraulic pressure control means. (Including etc.) are applied to vehicles equipped with.

The ABS is an ABS computer 1 for controlling a wheel speed sensor 14 as a vehicle starting state detecting means, an oil pressure sensor 17 for detecting a brake oil pressure as an abnormal sound generation area detecting means, and an ABS actuator 16.
It is composed of 8.

The wheel speed sensor 14 is capable of detecting the wheel rotation speed and is electrically connected to the ABS computer 18, that is, the wheel speed sensor 14 is connected to the wheel 20.
It is possible to detect not only the locked state but also the stopped state and the starting state of the vehicle. The ABS actuator 16 is connected to the wheel cylinder 23 of the disc brake 22 and also has a P & B (proportioning & bypass) valve 24.
It is connected to the brake master cylinder 26 via and can control the hydraulic pressure of the wheel cylinder 23. The ABS actuator 16 is electrically connected to an ABS computer 18. When the wheel speed sensor 14 detects the locked state of the wheel 20, the electric signal from the ABS computer 18 operates the ABS actuator 16 to increase or decrease the hydraulic pressure of the wheel cylinder 23.

Next, the operation of the brake noise suppressor 10 will be described with reference to the brake hydraulic pressure change diagram shown in FIG. 1 and the flow chart shown in FIG.

First, an abnormal noise when the vehicle starts at a very low speed is generated in a region where the creep force of the hydraulic automatic transmission 12 and the frictional force of the disc brake 22 (disc rotor and brake pad) are balanced. That is, as shown in FIG. 1B, in the conventional vehicle, when the brake hydraulic pressure in a state where the creep force of the automatic transmission 12 and the frictional force of the disc brake 22 are balanced is P ₀ , (P ₀ −Δp) < An abnormal noise of the brake is generated in the region where P <(P ₀ + Δp). Therefore, the abnormal noise of the brake is generated for a long time, which is a problem.

On the other hand, when the vehicle to which the above-described brake noise suppression device 10 is applied is started at a very slow speed from the stopped state, first, at step 100, the wheel speed sensor 1
Based on the signal from 4, it is determined whether the vehicle speed is 0, that is, whether the vehicle is stopped. Here, when the driver gradually releases the brake operation and the brake hydraulic pressure P by the ABS actuator 16 is reduced accordingly, the vehicle is gradually started due to the creep phenomenon of the automatic transmission 12.

Next, at step 102, the brake oil pressure P that is gradually reduced is a predetermined brake oil pressure (P ₀
The ABS computer 18 determines whether or not + Δp) is reached (that is, whether or not the abnormal noise generation region of the disc brake 22 is reached).

When the brake oil pressure P becomes equal to or less than the predetermined brake oil pressure (P ₀ + Δp) in step 102, the routine proceeds to step 104, where the brake oil pressure P is the predetermined brake oil pressure (P ₀ −) as shown in FIG. The brake hydraulic pressure of the wheel cylinders 23 is rapidly reduced by the ABS actuator 16 until Δp) is reached.

Therefore, the time when the abnormal noise of the brake is generated becomes extremely short, and as a result, the abnormal noise of the brake is prevented.

As described above, in the vehicle to which the brake noise suppression device 10 according to the present embodiment is applied, when the abnormal noise generation region is detected when the vehicle starts at a very low speed (the brake hydraulic pressure P is When the brake hydraulic pressure (P ₀ + Δp) is reached), the brake hydraulic pressure P is promptly changed to the brake hydraulic pressure (P
_{Since the} pressure is reduced until it reaches ₀ −Δp), in other words,
Since the frictional force of the disc brake 22 is rapidly reduced to quickly escape from the state of being in balance with the creep force of the hydraulic automatic transmission 12, the abnormal noise generation time is shortened, and as a result, the abnormal noise is prevented from occurring. It

In the first embodiment, when the abnormal noise generation region is detected when the vehicle starts at a very low speed (when the brake hydraulic pressure P reaches the brake hydraulic pressure (P ₀ + Δp)), the brake hydraulic pressure is promptly increased. P is the brake oil pressure (P ₀ −
Although the pressure is reduced until Δp) is reached, the pressure of the brake oil pressure P may be reduced to a value outside the region where the abnormal noise is generated. For example, the brake oil pressure P may be reduced to zero. Even in this case, similar to the above, the frictional force of the disc brake 22 quickly escapes from the state in which the frictional force of the automatic transmission 12 is in balance with the creep force of the automatic transmission 12, so that the generation of abnormal noise is prevented.

Further, in the first embodiment, the area where the abnormal noise is generated when the vehicle starts at a slow speed is detected based on the brake oil pressure P (the brake oil pressure P is the brake oil pressure (P
₍₀ + Δp) is detected), but the configuration is not limited to this, and the area in which abnormal noise is generated when the vehicle starts at a slow speed is also detected based on the movement of the vehicle (a state at a slow start). Good. In this case, the wheel speed sensor 1
Reference numeral 4 is also an abnormal sound generation area detecting means. FIG. 4 shows a flow chart of control of the brake oil pressure P in this case.

That is, when the vehicle starts at a slow speed from the stopped state, in step 110, the wheel speed sensor 14
Based on the signal from the vehicle, it is determined whether the vehicle speed is 0, that is, whether the disc brake 22 is operated. Here, the driver releases the brake operation,
When the brake oil pressure P is reduced, the vehicle gradually starts due to the creep phenomenon of the automatic transmission 12.

Next, at step 112, the ABS computer 18 determines whether or not the brake operation is released and the vehicle is gradually started at a very slow speed (that is, whether or not there is a possibility that the abnormal noise generation region of the disc brake 22 is reached).
Judged by

If the speed V of the vehicle is detected in step 112 and a slight start is confirmed, the process proceeds to step 114, and the brake oil pressure P is rapidly reduced until it reaches a predetermined brake oil pressure (P ₀ -Δp) as described above. To be done. Therefore, the time when the brake noise is generated becomes extremely short, and as a result, the brake noise is prevented.

As described above, even when the abnormal noise generation region is detected on the basis of the movement of the vehicle (the state in which the vehicle starts at a very low speed), the brake oil pressure P immediately changes when the vehicle starts at a very low speed. Since the frictional force of the disc brake 22 is quickly released from the state in which the frictional force of the disc brake 22 is in balance with the creep force of the automatic transmission 12 until P ₀ −Δp) is reached, abnormal noise is prevented.

Even in this case, the vehicle speed V
Is detected, and the brake hydraulic pressure P
May be reduced to 0.

Next, a second embodiment of the present invention will be described. The parts that are basically the same as those in the first embodiment have the first
The same reference numerals as in the embodiment are given and the description thereof is omitted.

Brake noise prevention device 3 according to the second embodiment
As shown in FIG. 2, 0 has basically the same configuration as the brake noise suppression device 10 according to the first embodiment described above. Further, the brake noise suppression device 30 operates according to a control program which will be described in detail later.

The abnormal noise (brake abnormal noise) generated when the vehicle starts moving at a very low speed is caused by the stick-slip of the disc brake 22, and the forced force of the stick-slip (the restraining force to be generated) is the fluid. Increases or decreases according to the creep force of the automatic transmission 12. That is, as shown in FIG. 6, μ: coefficient of static friction of disc brake 22 (disc rotor and brake pad) μ ′: coefficient of dynamic friction of disc brake 22 (disc rotor and brake pad) F: creep force of hydraulic automatic transmission 12 F _a : Stick-slip force P: If the hydraulic pressure of the disc brake 22 is used, then F _a = (μ−μ ′) P.

Furthermore, abnormal noise (brake abnormal noise) when the vehicle starts at a very low speed is generated in a region where the creep force of the hydraulic automatic transmission 12 and the frictional force of the disc brake 22 (disc rotor and brake pad) are balanced. To do. That is, F = μP.

Therefore, F_a= {(Μ-μ ') / μ} · F. As a result, the stick
Coxlip force F _aIs related to creep force F
It is understood that it is being done.

In this case, in the conventional vehicle, the creep force F of the automatic transmission 12 is large when starting at a very low speed,
For this reason, the stick-slip force F _a was large, and the abnormal noise of the brake was remarkable.

On the other hand, in the brake noise suppressor 30 according to the second embodiment, the creep force F is reduced when the vehicle starts to reduce the stick-slip force F _a and reduce the brake noise. 5 and the operation of the brake noise suppression device 30 is shown in a flow chart in FIG.

In the brake noise suppressor 30, when the vehicle starts at a very low speed from the stopped state, it is determined in step 120 whether the vehicle speed is 0 based on the signal from the wheel speed sensor 14, that is, the vehicle stops. It is judged whether or not it is. Further, in step 122, it is confirmed whether or not the accelerator operation is performed, that is, it is not the case that the accelerator operation is used together with the brake operation, for example, when the vehicle starts on a slope. On the other hand, if the accelerator is operated, it is determined that the starting torque is required (starting on a slope, etc.), the abnormal noise prevention control is stopped, and the starting control is performed.

Next, when the brake operation is gradually released by the driver, this is confirmed in step 124, and when the brake hydraulic pressure P is reduced, the vehicle is gradually started by the creep phenomenon of the automatic transmission 12. Further, in step 126, the automatic transmission 12 is shifted to a gear position other than the first speed (for example, the second speed, the third speed, or the O / D position).

Then, after it is confirmed in step 128 whether the brake is completely released, step 1
At 30, the automatic transmission 12 is shifted to the first speed and the process ends.

As described above, in the vehicle to which the brake noise suppressor 10 according to the second embodiment is applied, the automatic transmission 12 shifts to a gear position other than the first gear when the vehicle starts at a slight speed as described above. Since the speed is changed, in other words, the creep force F of the automatic transmission 12 is reduced, so the stick-slip force F _a is reduced, and as a result, abnormal noise is prevented.

It should be noted that which gear position the automatic transmission 12 is to be shifted to when the vehicle starts at a very slow speed may be appropriately set for each vehicle type according to the creep force F of the vehicle.

In the second embodiment, step 12
Although the automatic transmission 12 is configured to shift to a gear position other than the first speed when the release of the brake is confirmed in 4,
Not limited to this, when the brake oil pressure P detected by the oil pressure sensor 17 reaches the abnormal noise generation region: (P ₀ −Δp) <P <(P ₀ + Δp): as in the first embodiment described above. The automatic transmission 12 may be configured to shift to a gear position other than the first speed. FIG. 7 is a flow chart showing the operation in this case.

That is, when the vehicle starts at a slow speed from the stopped state, in step 131, the wheel speed sensor 14
Based on the signal from, it is determined whether the vehicle speed is 0 (whether the vehicle is stopped). Further, step 13
In 2, it is confirmed whether or not the accelerator operation is performed, that is, it is not the case that the accelerator operation is used together with the brake operation, for example, when the vehicle starts on a slope.

Next, when the driver gradually releases the brake operation to reduce the brake oil pressure P, and when this brake oil pressure P reaches the abnormal noise generation region (P ₀ + Δp), this is confirmed in step 134. Further, in step 136, the automatic transmission 12 is shifted to a gear position other than the first gear.

Then, after it is confirmed in step 138 whether or not the brake is completely released, in step 140, the automatic transmission 12 is operated to obtain the starting torque.
Is shifted to the 1st speed and the process ends.

As described above, even when the automatic transmission 12 is configured to be shifted to a gear position other than the first speed when the brake hydraulic pressure P reaches the abnormal sound generation region, the automatic transmission when the vehicle starts at a very low speed. The creep force F of 12 is reduced and the stick-slip force F _a is reduced, and as a result, generation of abnormal noise is prevented.

In each of the above-described embodiments, an example in which the brake noise suppression devices 10 and 30 are applied to a vehicle equipped with an ABS (antilock brake system) as a brake hydraulic pressure control means has been described, but the invention is not limited to this. No, for example, T
It may be applied to a vehicle equipped with an RC (traction control system) or a dedicated hydraulic control device.

Further, although the wheel speed sensor 14 is used as the vehicle starting state detecting means in the above-mentioned embodiment, a Doppler type ground vehicle speed sensor or a vehicle speed detecting device used in a speedometer may be used. Further, in the above-mentioned embodiment, when the brake is gradually released, if the abnormal noise is generated, the brake hydraulic pressure is reduced. However, if the brake is operated again (the brake hydraulic pressure is increased) while releasing the brake, The pressure reduction control by the ABS actuator 16 may be stopped.

Further, it should be additionally noted that the second embodiment has the following various embodiments in addition to the technical matters described in the claims.

The vehicle start state detecting means of the noise prevention device according to claim 2 is characterized by detecting that the vehicle starts without operating the accelerator when releasing the brake.

Further, the abnormal noise preventing apparatus according to the present invention comprises abnormal noise generating area detecting means for detecting an abnormal noise generating area of the brake, and outputs of the vehicle starting state detecting means and the abnormal noise generating area detecting means. Based on the above, the hydraulic automatic transmission is shifted to a gear position other than the first speed.

[0057]

As described above, the brake noise preventing device according to the present invention does not affect the original performance of the brake such as the brake efficiency and the "abnormal noise of the brake" when the vehicle starts due to the creep phenomenon. It has an excellent effect of being able to prevent the occurrence of

[Brief description of drawings]

FIG. 1A is a diagram showing a change in brake hydraulic pressure when a vehicle to which a brake noise reduction device according to a first embodiment of the present invention is applied is started at a very low speed, and FIG. 1B is a conventional vehicle. FIG. 7 is a diagram showing a change in brake hydraulic pressure when the vehicle starts at a very low speed.

FIG. 2 is an overall configuration diagram of a brake noise suppressor according to first and second embodiments of the present invention.

FIG. 3 is a flow chart showing a control program of the brake noise suppression device according to the first embodiment of the present invention.

FIG. 4 is a flow chart showing a control program of a brake noise suppression device according to a modification of the first embodiment of the present invention.

FIG. 5 is a flow chart showing a control program of the brake noise suppression device according to the second embodiment of the present invention.

FIG. 6 is a diagram showing a stick-slip phenomenon of a disc brake in relation to a frictional force.

FIG. 7 is a flow chart showing a control program of a brake noise suppressor according to a modification of the second embodiment of the present invention.

[Explanation of symbols]

 10 Brake Abnormal Noise Prevention Device 12 Automatic Transmission 14 Wheel Speed Sensor 16 ABS Actuator 17 Hydraulic Pressure Sensor 18 ABS Computer 20 Wheels 22 Disc Brake 30 Brake Noise Reduction Device

Claims (2)

[Claims] 1. A brake noise suppressor applied to a vehicle, comprising: a fluid type automatic transmission; and a brake hydraulic pressure control means for controlling the brake hydraulic pressure according to the running state of the vehicle, wherein the vehicle stops. Vehicle starting state detecting means for detecting the start of the vehicle due to the output of the hydraulic automatic transmission when the brake is released from the state, and abnormal noise generation area detection for detecting the abnormal noise generation area of the brake in the starting state of the vehicle Means for reducing the brake hydraulic pressure by the brake hydraulic pressure control means based on the outputs of the vehicle start state detection means and the abnormal noise generation area detection means. 2. A brake noise suppressor applied to a vehicle having a fluid automatic transmission, wherein the brake is released from a stopped state of the vehicle to start the vehicle by the output of the fluid automatic transmission. A brake noise suppression device comprising: vehicle start state detecting means for detecting, and based on an output of the vehicle start state detecting means, shifting the hydraulic automatic transmission to a gear position other than first gear.