JP2009143273A - Braking force controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force controller that prevents the deterioration of braking feeling by recurrence of squeal of brake etc. <P>SOLUTION: The braking force controller, which controls the braking force of each wheel by controlling braking frictional force generated in a braking device of each wheel according to the stepped-down amount of a brake pedal, comprises a brale noise detection means, which starts detecting brale noise only when vehicle speed is less than predetermined speed, when outside air temperature is less than predetermined temperature, and when it is before predetermined time elapses after starting an engine; a registration means, which registers a hydraulic force applied to the wheels when the brale noise is detected by the brale noise detection means in either one of the wheels as a hydraulic force that should be avoided; and a braking force controlling means, which changes the braking frictional force of the wheel so as to avoid the hydraulic force that is registered by the registration means as the hydraulic force that must be avoided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a braking force control device.

  2. Description of the Related Art Conventionally, a brake device for a vehicle such as an automobile generally has a rotating member such as a brake rotor and a brake drum that rotates together with wheels, and a movable member such as a brake pad and a brake shoe that are driven in response to depression of a brake pedal. A braking frictional force is generated by pressing the friction material of the movable member against the rotating member, thereby braking the wheel.

  As is well known, for example, when the brake device is operated so that the braking frictional force is maintained at a substantially constant force that is relatively low, the vibration of the constituent members of the brake device such as the movable member is self-excited, An unpleasant noise with a relatively high frequency called a brake squeal may occur.

  As a braking force control device for preventing such brake squeal, for example, the following techniques are known.

For example, Patent Document 1 discloses a technique for preventing pressure by reducing pressure when there is a possibility of occurrence of brake squeal by an acceleration sensor. Patent Document 2 discloses a technique for detecting the friction material temperature, vehicle speed, pressing force, and the like and controlling the pressing force of the friction material when the possibility of occurrence of squeal is high. Furthermore, Patent Literature 3 discloses a technique for detecting a condition with high occurrence of squeal including air temperature and a vehicle cold state and controlling the brake pressure. Furthermore, Patent Document 4 discloses a technique for controlling the brake pressure by detecting a high squealing condition including temperature, vehicle cold state, vehicle speed, braking force, and the like.
JP-A-10-305768 Japanese Patent Laid-Open No. 2005-319913 JP 2004-268703 A JP 2004-284398 A

  However, in the conventional braking force control device as described above, there are problems such as a renewed brake squeal and a deterioration in brake feeling due to a change in oil pressure (hydraulic pressure value) for preventing brake squeal. It was. This is because the oil pressure is changed after the brake squeal is detected, and there is no upper limit to the oil pressure that should be avoided to prevent the brake squeal.

  The present invention has been invented in order to solve this problem in view of the above points, and aims to provide a braking force control device that prevents deterioration of brake feeling due to reoccurrence of brake squealing or the like. To do.

  In order to achieve the above object, the braking force control device according to the present invention controls the braking force of each wheel by controlling the braking friction force generated in the braking device of each wheel according to the depression amount of the brake pedal. Brake squeal detecting means for starting detection of brake squeal only when the vehicle speed of the vehicle is less than a predetermined speed, the outside air temperature is less than a predetermined temperature, and a predetermined time has elapsed after the engine is started A registration means for registering as an oil pressure to be avoided an oil pressure applied to the wheel when a brake squeal is detected by the brake squeal detection means in any of the wheels, and registered by the registration means A braking force control means for changing the braking frictional force of the wheel so as to avoid the oil pressure to be avoided can be provided.

  In order to achieve the above object, the registration means according to the present invention further sets the vehicle pressure and the outside air temperature of the vehicle when the brake squeal is detected by the brake squeal detecting means to the oil pressure to be avoided. The braking force control means controls the wheel so as to avoid the hydraulic pressure to be avoided registered by the registration means in association with the current vehicle speed and the current outside air temperature of the vehicle. The dynamic friction force can be changed.

  In order to achieve the above object, the registration means according to the present invention further includes the oil to be avoided when the brake pressure is detected by the brake squeal detection means and the oil pressure actually applied to the wheel is detected. When registering as pressure, if the pressure value width of the oil pressure to be avoided already registered exceeds a predetermined width, the pressure value width of the oil pressure to be avoided can be reduced.

  Further, in order to achieve the above object, the predetermined width in the present invention is configured to be switched according to the hydraulic pressure actually applied to the wheel when the brake squeal is detected by the brake squeal detecting means. be able to.

  In order to achieve the above object, the braking force control apparatus according to the present invention has an ECB that generates a braking force independently for each wheel during braking, and the ECB is controlled by the braking force control means. Each wheel can be controlled to compensate for a change in dynamic friction force.

  ADVANTAGE OF THE INVENTION According to this invention, the braking force control apparatus which prevents the deterioration of the brake feeling by the recurrence of a brake squeal, etc. can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Embodiment]
(System configuration)
FIG. 1 is a diagram illustrating an example of a configuration of a braking force control device according to the present embodiment. In FIG. 1, the braking force control device 1 has a configuration including a brake squeal detection device 10, a hydraulic brake system 20, an ECU 30, an outside air temperature meter 40, a wheel speed sensor 50, and the like. Such a braking force control device 1 is mounted on a vehicle such as an automobile.

  Hereinafter, each component in FIG. 1 will be described.

  The brake squeal detection device 10 is a device that detects a brake squeal. For example, the brake squeal is detected based on the frequency of sound data detected by a sound measuring device attached to each wheel of the vehicle. Various methods for detecting the brake squeal have been proposed, and a detailed description thereof will be omitted here. For example, a brake squeal determination device disclosed in Japanese Patent Application Laid-Open No. 2003-14536.

  The hydraulic brake system 20 includes a hydraulic control unit 21, a hydraulic brake 22, and the like, and is a brake system that performs braking using hydraulic pressure.

  The hydraulic control unit 21 performs control related to the hydraulic pressure applied to the hydraulic brake 22. The hydraulic brake 22 is a brake device that transmits a braking force to each wheel using the hydraulic pressure of liquid (brake oil). For example, hydraulic pressure is generated in the master cylinder in accordance with the amount of depression applied to the brake pedal of the vehicle by the vehicle user. Subsequently, this hydraulic pressure is transmitted to the cylinder of each wheel via a brake pipe, and the piston of the cylinder of each wheel is pushed out. As a result, the piston presses the pad and brake shoe against the disc and drum to generate braking force on each wheel.

  The ECU 30 is a microcontroller for performing various controls performed by the braking force control device 1. The various controls are, for example, control of braking friction force generated in the hydraulic brake system 20. Thereby, the braking force of each wheel can be controlled. Also, it has a function as a registering means for registering various information (for example, oil pressure to be avoided for preventing brake squealing) used in the control of the braking friction force in the storage device (storage means). . An example of the control operation performed by the ECU 30 will be described in an operation example described later.

  The outside air temperature meter 40 is a measuring device that measures the outside air temperature. The wheel speed sensor 50 is a so-called vehicle speed sensor for measuring the rotational speed of the wheel.

  With the configuration described above, the braking force control apparatus 1 performs control related to the braking force so that the brake feeling is not deteriorated due to the reoccurrence of brake squealing or the like.

  In addition, the vehicle including the braking force control device 1 according to the present embodiment has an ECB (Electric Control Braking system), and the operation amount of the brake pedal is detected by a sensor, and the braking force by the hydraulic brake is applied to each wheel. It is assumed that the brakes of each wheel can be optimally controlled independently.

(Operation example)
FIG. 2 is a diagram illustrating an example of an operation sequence of the braking force control apparatus according to the present embodiment. Here, an example of the operation of the braking force control apparatus 1 of FIG. 1 will be described with reference to FIG. The operation shown in this operation example will be described on the assumption that the operation is performed when the brake pedal of the vehicle is depressed by the vehicle user while the vehicle including the braking force control device 1 is traveling.

  First, it is determined whether or not the vehicle speed is less than a predetermined speed Vt (S1). Here, the ECU 30 determines whether or not the vehicle speed is less than a preset speed Vt (for example, 10 km / h) based on the rotational speed of the wheel measured by the wheel speed sensor 50. This process is a process for determining whether or not a low-speed state, which is one of the conditions where brake squeal is likely to occur, is satisfied. The threshold speed Vt may be a value set for each vehicle.

  Subsequently, the process proceeds to step S2, and it is determined whether or not the outside air temperature is lower than a predetermined temperature Tout (S2). Here, the ECU 30 determines whether or not the outside air temperature measured by the outside air temperature meter 40 is lower than a preset temperature Tout (for example, 10 ° C.). This process is a process for determining whether or not a low temperature state, which is one of the conditions where brake squeal easily occurs. The temperature Tout serving as a threshold may be a value set for each vehicle.

  Subsequently, the process proceeds to step S3, where it is determined whether or not the time after engine startup is less than a predetermined time Ton (S3). Here, the ECU 30 determines whether or not the time after engine startup is less than a preset time Ton (for example, 5 minutes), that is, whether or not the time Ton has elapsed after engine startup. This process is a process for determining whether or not the condition is satisfied after the engine is started, which is one of the conditions in which brake squeal is likely to occur. The threshold time Ton may be a value set for each vehicle.

  If YES in the processes according to steps S1 to S3 described above, that is, if any of the vehicle speed, the outside air temperature, and the engine post-start time is less than the predetermined value, the process proceeds to step S4 to start detection of brake squeal (S4). . Here, the brake squeal detection device 10 starts detecting the brake squeal when the conditions shown in steps S1 to S3 are satisfied.

  It should be noted that NO in any of the processes related to steps S1 to S3, that is, if any of the vehicle speed, the outside air temperature, and the time after engine start is not less than a predetermined value and does not satisfy the condition that the brake squeal is likely to occur. Then, the process ends.

  Thus, by limiting the start of brake squeal detection according to step S4 to conditions that are particularly likely to cause squeal (for example, low speed, low temperature, predetermined time after engine start), unnecessary brake squeal detection is not performed. It will be good.

  Further, for example, the vehicle speed, the outside air temperature, etc. when the brake squeal occurred during the previous run is registered in advance in the storage device of the ECU 30, and each registered value can be set as each predetermined value (described later). (See step S6). Thereby, the occurrence condition of the brake squeal at the time of the previous travel is actually used as the condition for detecting the brake squeal at the time of travel, so that the recurrence of the brake squeal can be prevented and the accuracy related to detection of the brake squeal can be further improved.

  Subsequently, the process proceeds to step S5 to determine whether or not there is a brake squeal (S5). Here, the brake squeal detection device 10 that has started detection of brake squeal by the process according to step S4 determines (detects) whether or not there is a brake squeal in any wheel of the vehicle.

  If YES in step S5, that is, if there is a brake squeal (S5, YES), the process proceeds to step S6. If NO in step S5, that is, if there is no brake squeal (S5, NO), the process proceeds to step S7.

  When the process proceeds to step S6, the brake squealing condition is stored (S6). Here, the ECU 30 registers the hydraulic pressure applied to the wheel when the brake squeal is detected in step S5 in the storage device as the hydraulic pressure to be avoided, which is one of the conditions of the brake squeal. Since the oil pressure to be avoided generally has a certain width (for example, 2.9 MPa to 3.1 MPa), the oil pressure to be avoided registered in the storage device is an oil pressure having such a certain width ( In the following description, it is referred to as “hydraulic belt to be avoided”).

  In step S6, preferably, the vehicle speed of the vehicle, the outside air temperature, the frequency of the brake squeal detected by the brake squeal detection device 10, the wheel from which the brake squeal has been detected, and the like are associated with the hydraulic belt to be avoided. Register in the storage device.

  The reason for registering the vehicle speed and the outside air temperature is to further improve the accuracy related to the detection of the brake squeal, for example, by using the brake squeal generation condition during the previous run for the detection of the brake squeeze during the run as described above. .

  The reason for registering the frequency of the brake squeal is to be able to distinguish between the hydraulic band that should be avoided and the hydraulic band that should not be used, according to the frequency of the brake squeal. For example, when it is not particularly desired to generate one of the two types of brake squealing, which is divided into two types, that is, a high frequency brake squeal and a low frequency brake squeal, the hydraulic band to be avoided associated with the one brake squeal Use only. Thereby, the spread of the hydraulic belt to be avoided can be suppressed. Specifically, for example, when it is not particularly desirable to generate a brake squeal having a high frequency, a hydraulic band to be avoided associated with a brake squeal having a high frequency (above a predetermined frequency) is used, but the frequency is low ( (Below the predetermined frequency) Do not use the hydraulic band to be avoided that is associated with the brake squeal.

  When the process proceeds to step S7, the brake squeal conditions are read (S7). Here, the ECU 30 reads out a hydraulic pressure band to be avoided, which is one of the brake squeal conditions registered in the storage device. Thereafter, the process proceeds to step S10.

  In step S7, although a brake squeal is not detected at the present time, a hydraulic pressure band to be avoided registered in the storage device is read in order to avoid a brake squeeze that may occur in the future. This process makes it possible to avoid a brake squeal that occurs under the same conditions as when a brake squeal was detected during the previous braking.

  Further, the hydraulic belt to be avoided to be read in step S7 can be separated in advance for each combination of brake squeal conditions such as the vehicle speed, the outside air temperature, and the brake squeal frequency registered in step S6. As a result, for example, control is performed so as to avoid only the hydraulic belt that should be avoided, which is associated with the current vehicle speed and the current outside air temperature of the vehicle, and avoidance of unnecessary hydraulic belts can be avoided. Ring change can be suppressed.

Subsequently, the process proceeds to step S8, and it is determined whether or not the hydraulic band to be avoided is equal to or greater than a predetermined width ΔP _NG (S8). Here, the ECU 30 determines whether or not the hydraulic pressure zone to be avoided accumulated by the registration process according to step S6 is equal to or greater than the predetermined width ΔP _NG . This will be specifically described with reference to FIG.

  FIG. 3 is a diagram for explaining, in chronological order, a hydraulic band when a brake squeal occurs. Usually, the hydraulic belt in which brake squeal occurs (hydraulic belt to be avoided) tends to shift to a larger (or smaller) pressure value over time due to wear of the brake device or the like. For example, FIG. 3 shows a state in which the hydraulic pressure band at the time of occurrence of brake squealing shifts from A → B → C → D to the larger pressure value as time passes.

  At this time, due to the registration process according to step S6, the hydraulic band at the time of occurrence of the brake squeal is accumulated in the storage device as the hydraulic band to be avoided. Here, it is assumed that A to D (the pressure value width of each hydraulic band is ΔP1) are already registered as hydraulic bands to be avoided. Here, for example, when the hydraulic band at the time of occurrence of the brake squeal to be registered is E, when the hydraulic band E is registered, the entire width of the hydraulic band to be avoided is A to E. However, in view of the above-described tendency, for example, in the hydraulic belt A, the brake squeal no longer occurs, but it is still registered as a hydraulic belt to be avoided. In this state, a feeling change occurs by avoiding all of the hydraulic zones A to E.

For this reason, according to the present embodiment, the hydraulic pressure band (here, the hydraulic pressure band indicated by the hatched portion in FIG. 3) is the farthest from the hydraulic pressure band (here, the hydraulic pressure band E) at the time of occurrence of the brake squeal to be registered. Remove A) from the hydraulic belt that should be avoided. That is, when the pressure value width of the oil pressure that should be avoided already registered exceeds a predetermined width ΔP _NG (for example, 1 MPa), the pressure value width of the oil pressure that should be avoided is reduced. As a result, it is possible to avoid unnecessary oil pressure and suppress a change in feeling.

Note that the set value of the predetermined width ΔP _NG in step S8 is desirably variable (switched) according to the oil pressure at the time of occurrence of the brake squeal to be registered. Specifically, the predetermined width ΔP _NG when the hydraulic pressure at the time of occurrence of brake squeal is low is made narrower than that when it is high. This is because, as shown in FIG. 4, the width of the hydraulic band where the brake squeal is generally narrower than when the oil pressure when the brake squeal is low is higher. FIG. 4 is a diagram for explaining high hydraulic brake noise and low hydraulic brake noise. FIG. 4 shows that each brake squeal is generated by a combination of a bounce mode (A) with a large frequency change and a small pitching mode (B).

If YES in step S8, that is, if the hydraulic pressure band to be avoided is greater than or equal to the predetermined width ΔP _NG (S8, YES), the process proceeds to step S9 to perform the avoiding hydraulic pressure band reduction calculation (S9). Here, ECU 30, as described above, avoiding the currently hydraulic zone pressure value from the hydraulic band when brake noise occurs to be registered is farthest of the hydraulic zone to be avoided, which becomes equal to or larger than a predetermined width [Delta] P _NG Perform the calculation to exclude from the hydraulic range to be performed.

  Then, it moves to step S10 and changes the oil pressure of the wheel where the brake squeal has occurred (S10). Here, the ECU 30 should be read out to the hydraulic pressure control unit 21 so as to avoid the hydraulic band to be avoided which has been subjected to the reduction operation in step S9 or the hydraulic band to be avoided read out in step S7. The braking friction force of the wheel is changed so as to avoid the hydraulic belt. Thereby, brake squeal can be prevented.

  Subsequently, the process proceeds to step S11, and the four-wheel total braking force moment is adjusted (S11). Here, the ECU 30 controls the hydraulic pressure of each of the other wheels using the ECB to compensate for the change in the wheel oil pressure performed in step S10, thereby keeping the braking force constant and suppressing the generation of moment. For example, when a hydraulic pressure zone to be avoided is avoided so as to prevent brake squealing on the right front wheel of the vehicle, the hydraulic pressure or the like on the right rear wheel of the vehicle is controlled to compensate for this change in hydraulic pressure. At this time, it is desirable to optimize in consideration of the hydraulic belt to be avoided that is registered in association with each wheel by the processing according to step S6 so that the brake squeal does not occur at other wheels.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the requirements shown here, such as combinations with other elements listed in the above embodiments. With respect to these points, the present invention can be changed within a range that does not detract from the gist of the present invention, and can be appropriately determined according to the application form.

It is a figure which shows an example of a structure of the braking force control apparatus which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the braking force control apparatus which concerns on this embodiment. It is a figure for demonstrating to a time series the hydraulic belt | band | zone at the time of brake squeal generation | occurrence | production. It is a figure for demonstrating a high hydraulic brake squeal and a low hydraulic brake squeal.

Explanation of symbols

1 Braking Force Control Device 10 Brake Squeal Detection Device 20 Hydraulic Brake System 30 ECU
40 Outside temperature sensor 50 Wheel speed sensor

Claims (5)

A braking force control device that controls the braking force of each wheel by controlling the braking friction force generated in the braking device of each wheel according to the depression amount of the brake pedal,
Brake squeal detection means for starting detection of brake squeal only when the vehicle speed of the vehicle is less than a predetermined speed, the outside air temperature is less than a predetermined temperature, and a predetermined time has elapsed after the engine is started,
Registration means for registering as an oil pressure to be avoided the oil pressure applied to the wheel when brake squeal is detected by the brake squeal detection means in any of the wheels;
Braking force control means for changing the braking frictional force of the wheel so as to avoid the oil pressure to be avoided registered by the registration means;
A braking force control device comprising: The registration means further registers the vehicle speed and the outside air temperature of the vehicle when the brake squeal is detected by the brake squeal detection means in association with the oil pressure to be avoided,
The braking force control means changes the braking friction force of the wheel so as to avoid the hydraulic pressure to be avoided registered by the registration means in association with the current vehicle speed and the current outside air temperature of the vehicle. The braking force control apparatus according to claim 1.   The registration means should further avoid the already registered oil pressure when registering the oil pressure that is actually pressurized to the wheel when the brake squeal is detected by the brake squeal detection means as the oil pressure to be avoided. The braking force control device according to claim 1 or 2, wherein when the pressure value width of the oil pressure exceeds a predetermined width, the pressure value width of the oil pressure to be avoided is reduced.   The said predetermined width switches according to the oil pressure which was actually pressurized to the said wheel when the brake squeal is detected by the said brake squeal detection means, The Claim 1 thru | or 3 characterized by the above-mentioned. Braking force control device. It has an ECB that generates braking force on each wheel independently during braking,
5. The braking force control apparatus according to claim 1, wherein the ECB controls each of the wheels to compensate for a change in braking friction force by the braking force control unit.

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