Title: Brake noise detection device
Abstract: An output signal that accords with a rotation speed of a brake rotor of a respective wheel is output by a vehicle wheel speed sensor. A noise frequency identification portion identifies a frequency component that corresponds to brake noise from this output signal. It is possible, for example, to identify a frequency component that corresponds to brake squeal by performing fast Fourier transform (FFT) calculation for the vehicle wheel speed. Further, a noise detection portion determines that brake noise is being generated when the frequency component identified by the noise frequency identification portion is equal to or more than a predetermined value.
Patent Number: 6,898,976 Issued on 05/31/2005 to Kamiya, et al.
| Inventors:
|
Kamiya; Masahiko (Anjo, JP);
Kondo; Hiroshi (Chiryu, JP);
Sasaki; Shin (Okazaki, JP);
Oba; Daizo (Kariya, JP)
|
| Assignee:
|
Advics Co., Ltd. (Aichi-pref., JP)
|
| Appl. No.:
|
779618 |
| Filed:
|
February 18, 2004 |
Foreign Application Priority Data
| Mar 24, 2003[JP] | 2003-079685 |
| Current U.S. Class: |
73/593; 73/659; 73/660 |
| Intern'l Class: |
G01N 029/04 |
| Field of Search: |
73/593,579,597,600,602,659,660
|
References Cited [Referenced By]
U.S. Patent Documents
| 4028686 | Jun., 1977 | Wilson et al.
| |
| 4720794 | Jan., 1988 | Skarvada.
| |
| 4724935 | Feb., 1988 | Roper et al.
| |
| 5728938 | Mar., 1998 | Choi et al.
| |
| 5948961 | Sep., 1999 | Asano et al.
| |
| 6254204 | Jul., 2001 | Hara et al.
| |
| 6264292 | Jul., 2001 | Umeno et al.
| |
| 6687644 | Feb., 2004 | Zinke et al.
| |
| Foreign Patent Documents |
| A-2000-283193 | Oct., 2000 | JP.
| |
Primary Examiner: Williams; Hezron
Assistant Examiner: Saint-Surin; Jacques M.
Attorney, Agent or Firm: Posz Law Group, PLC
Claims
1. A brake noise detection device comprising:
a vehicle wheel speed sensor that outputs an output signal in accordance with
a rotation speed of a vehicle wheel;
a noise frequency identification portion that identifies a frequency component
that corresponds to brake noise based on the output signal of the vehicle wheel
speed sensor; and
a noise detection portion that determines that brake noise is being generated
when the frequency component identified by the noise frequency identification portion
is equal to or more than a predetermined value.
2. The brake noise detection device according to claim 1, wherein
the vehicle wheel speed sensor includes a detected portion configured from a
plurality of detected bodies which are disposed on at least one of an external
circumference surface and a rotating surface of a rotating body that rotates integrally
with the vehicle wheel, the detected bodies being disposed at equal distances apart
in a circumferential direction of the rotating body; and a detection portion that
is disposed so as to face the detected portion with a distance of separation, and
the detection portion outputs a signal in accordance with a relative movement
speed of the detected portion and the detection portion.
3. The brake noise detection device according to claim 2, wherein
the plurality of detected bodies in the detected portion are provided as between
five hundred to one thousand detected bodies that are disposed at equal distances
of separation.
4. The brake noise detection device according to claim 3, wherein
the noise frequency identification portion includes a vehicle wheel speed calculation
portion which calculates a rotation speed of the vehicle wheel based upon the output
signal of the vehicle wheel speed sensor, and which outputs a rotation speed signal
based upon the calculated rotation speed; and a frequency calculation portion that
calculates a frequency spectrum of the vehicle wheel speed by performing fast Fourier
transform for the rotation speed signal of the vehicle wheel.
5. The brake noise detection device according to claim 3, wherein
the noise frequency identification portion includes a frequency spectrum calculation
portion that performs fast Fourier transform of the output signal of the vehicle
wheel speed sensor; and a portion that excludes a frequency component that corresponds
to the vehicle wheel speed from an output of the frequency spectrum calculation
portion.
6. The brake noise detection device according to claim 2, wherein
the noise frequency identification portion includes a vehicle wheel speed calculation
portion which calculates a rotation speed of the vehicle wheel based upon the output
signal of the vehicle wheel speed sensor, and which outputs a rotation speed signal
based upon the calculated rotation speed; and a frequency calculation portion that
calculates a frequency spectrum of the vehicle wheel speed by performing fast Fourier
transform for the rotation speed signal of the vehicle wheel.
7. The brake noise detection device according to claim 2, wherein
the noise frequency identification portion includes a frequency spectrum calculation
portion that performs fast Fourier transform of the output signal of the vehicle
wheel speed sensor; and a portion that excludes a frequency component that corresponds
to the vehicle wheel speed from an output of the frequency spectrum calculation
portion.
8. The brake noise detection device according to claim 1, wherein
the noise frequency identification portion includes a vehicle wheel speed calculation
portion which calculates a rotation speed of the vehicle wheel based upon the output
signal of the vehicle wheel speed sensor, and which outputs a rotation speed signal
based upon the calculated rotation speed; and a frequency calculation portion that
calculates a frequency spectrum of the vehicle wheel speed by performing fast Fourier
transform for the rotation speed signal of the vehicle wheel.
9. The brake noise detection device according to claim 1, wherein
the noise frequency identification portion includes a frequency spectrum calculation
portion that performs fast Fourier transform of the output signal of the vehicle
wheel speed sensor; and a portion that excludes a frequency component that corresponds
to the vehicle wheel speed from an output of the frequency spectrum calculation
portion.
10. The brake noise detection device according to claim 1, wherein
the vehicle wheel speed sensor is disposed within a caliper.
Description
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Application
No. 2003-079685 filed on Mar. 24, 2003, the content of which are incorporated herein
by reference.
FIELD OF THE INVENTION
The present invention relates to a brake noise detection device.
BACKGROUND OF THE INVENTION
Conventional art is known for detecting generation of brake noise, such
as brake squeal (for example, Japanese Patent Laid-Open Publication No. 2000-28319).
In such art, a vibration frequency of at least one of a brake torque and a caliper
pressing force is detected, and then it is determined that shudder is being caused
when this vibration frequency is proportional to vehicle speed.
However, with this related art, it is necessary to specially provide a load
sensor that detects brake load or a torque sensor that detects the brake torque
within the caliper in order to detect the brake torque or the caliper pressing
force. Accordingly, such art is both complicated and expensive.
SUMMARY OF THE INVENTION
In light of the above described problems, it is an object of the present invention
to detect brake noise using a simple structure that does not require specialist
sensors like vibration sensors to be provided.
In order to accomplish the above object, a brake noise detection device according
to a first aspect of the present invention is provided with a vehicle wheel speed
sensor that outputs an output signal in accordance with a rotation speed of a vehicle
wheel; a noise frequency identification portion for identifying a frequency component
that corresponds to brake noise based on the output signal of the vehicle wheel
speed sensor; and a noise detection portion for determining that brake noise is
being generated when the frequency component identified by the noise frequency
identification portion is equal to or more than a predetermined value.
According to the first aspect of the present invention, when the frequency
component included within the output signal of the vehicle wheel speed sensor that
corresponds to brake noise is equal to or more than the predetermined value, it
is determined that brake noise is being generated. Accordingly, it is possible
to easily detect brake noise using the vehicle wheel speed sensor that is included
in a normal brake apparatus, without having to provide a special sensor.
The first aspect may also be configured such that the vehicle wheel speed sensor
includes a detected portion configured from a plurality of detected bodies which
are disposed on at least one of an external circumference surface and a rotating
surface of a rotating body that rotates integrally with the vehicle wheel, these
detected bodies being disposed at equal distances apart in a circumferential direction
of the rotating body; and a detection portion that is disposed so as to face the
detected portion with a distance of separation. Further, the detection portion
may output a signal in accordance with a relative movement speed of the detected
portion and the detection portion.
In other words, it is possible to dispose the detected bodies on the external
circumference surface of the rotating body or the rotating surface of the rotating
body, as with a normal brake apparatus. In particular, when the detected bodies
are disposed on the rotating surface and, in accordance with this, the detection
portion is disposed so as to face the detected bodies and be perpendicular to the
rotating surface, it is possible to detect surface swing of the rotating body that
accompanies the generation of brake noise, such as brake squeal, during braking.
Accordingly, it is possible to reliably detect brake noise.
Moreover, the configuration of the present invention may be such that the
plurality of detected bodies in the detected portion are provided as between five
hundred to one thousand detected bodies that are disposed at equal distances of
separation. The number of the detected bodies is set such that, at low vehicle
speed when brake noise is easily generated, the output signal of the vehicle wheel
speed sensor is within a frequency band that is substantially equal to the frequency
of brake noise. Accordingly, it is possible to accurately identify a frequency
signal that corresponds to brake noise.
Moreover, the configuration of the present invention may be such that the
noise frequency identification portion includes a vehicle wheel speed calculation
portion that calculates a rotation speed of the vehicle wheel based upon the output
signal of the vehicle wheel speed sensor; and a frequency calculation portion that
calculates a frequency spectrum of the vehicle wheel speed by performing fast Fourier
transform for the calculated rotation speed of the vehicle wheel. Furthermore,
the configuration may be such that the noise frequency identification portion includes
a frequency spectrum calculation portion that performs fast Fourier transform of
the output signal of the vehicle wheel speed sensor; and a portion that excludes
the frequency component that corresponds to the vehicle wheel speed from an output
of the frequency spectrum calculation portion.
Moreover, the configuration of the present invention may be such that the
vehicle wheel speed sensor is disposed within a caliper.
According to the above described configuration of the present invention,
the vehicle wheel speed sensor can estimate changes in positional displacement
of a caliper case and a brake case. Accordingly, it is possible to detect vibration
of the caliper that occurs when brake noise of the caliper is generated, without
utilizing a vibration sensor.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the present invention will be understood
more fully from the following detailed description made with reference to the accompanying
drawings. In the drawings:
FIG. 1 is a schematic view showing a configuration of a first embodiment of
the present invention;
FIG. 2 is a schematic view showing a configuration of a vehicle wheel speed sensor;
FIG. 3 is a chart showing an output waveform of the vehicle wheel speed sensor;
FIG. 4 is a chart showing a relationship between an output amplitude of the
vehicle wheel speed sensor and a rotation speed;
FIG. 5 is a flow chart showing a procedure for brake noise detection and inhibition
processing that is executed by an ECU 3 of the first embodiment;
FIG. 6 is a graph showing a time waveform of a vehicle wheel speed;
FIG. 7 is a diagram showing results attained by performing fast Fourier transform
(FFT) calculation of variation of the vehicle speed;
FIG. 8 is a flow chart showing a procedure for brake noise detection and inhibition
processing that is executed by the ECU 3 of a second embodiment;
FIG. 9 is a schematic view showing the positioning of a vehicle wheel speed
sensor in a third embodiment; and
FIG. 10 is a schematic view showing the positioning of a vehicle wheel speed
sensor in a fourth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will be described further with reference to various embodiments
in the drawings.
First Embodiment
Hereinafter, a first embodiment of a brake noise detection device according
to the present invention will be explained with reference to the figures. FIG.
1 is a schematic view showing a configuration of the first embodiment.
As shown in FIG. 1, the brake noise detection device of the first embodiment
is
provided with a brake pedal
1 that is operated by a driver; a depression
force sensor
2 that detects a pedal depression force as a depression state
of the brake pedal
1; a electronic control unit (hereinafter referred to
as "ECU")
3 configured from a computer that receives a detection signal
from the depression force sensor
2; a drive unit
4 that is controlled
by the ECU
3; and actuators (a brake force generation portion)
5a
to
5d for brake actuation which are provided in each wheel
6a
to
6d and which generate brake force for the respective vehicle
wheels
6a to
6d, as a result of actuation of the drive
unit
4.
The actuators
5a to
5d for brake actuation are configured
from, for example, a motor, and a disk brake or a drum brake, or the like, that
is driven by the motor. The drive unit
4, which is controlled by the ECU
3, executes adjustment of brake force by adjusting an amount of current
fed to the motor. In addition, when an indicated current flows due to the drive
unit
4, based on an instruction from the ECU
3, the actuators
5a
to
5d for brake actuation generate brake force such that it is
proportional to the indicated current.
Further, respective vehicle wheel speed sensors
7a to
7d
that generate respective signals in accordance with rotation are provided in
each of the wheels
6a to
6d. The vehicle wheel speed
sensors
7a to
7d are connected to the ECU
3.
Note that, FIG. 2 only shows, among the vehicle wheel speed sensors
7a
to
7d, the vehicle wheel speed sensor
7a for the
first wheel
6a. The vehicle wheel speed sensor
7a is
configured from protruded and grooved teeth
61 and a magnetic pickup
70.
The teeth
61, of which there are a predetermined number (from 500 to 1000),
are formed at equal distances apart in a circumferential direction around an external
periphery surface of a brake disk rotor
60, which acts as a rotating body
for the respective wheel
6a. The teeth
61 are formed from
a magnetic material such as steel and act as a detected body. The magnetic pickup
70 acts as a detection portion and is disposed so as to face the row of
teeth
61 with a distance of separation.
Note that, the magnetic pickup
70 uses a known method in which an alternating
current signal is generated by variation of magnetic flux that links with a coil
(not shown) within the detection portion. The magnetic flux varies along with relative
positional change of the magnetic pickup
70 with respect to the teeth
61
formed from steel or the like. Accordingly, due to the properties of the magnetic
pickup
70, respective output signals of the vehicle wheel speed sensors
7a to
7d, as shown by the output waveform chart in
FIG. 3, have a frequency and an amplitude An that become larger in accordance with
a movement speed of the teeth
61 that are the detected body, namely, a rotation
speed of the brake disk rotor
60. In FIG. 3, An
1 and An
2 indicate
the respective output waveforms from the vehicle wheel speed sensors
7a
to
7d at a low rotation speed and a high rotation speed, respectively.
FIG. 4 shows the relationship between the amplitude An of the output signal and
a rotation speed n. As is clearly apparent, the amplitude An has a proportional
relationship to the rotation speed n, namely, a vehicle wheel speed V.
As an example, when a vehicle with 700 mm diameter tires is running at 20 km
per
hour, which is within a vehicle speed range at which brake noise is easily generated,
the respective output signals of the vehicle speed sensors
7a to
7d are alternating current signals with a frequency of 2.53 kHz when
the tooth number is 1000, and a frequency of 1.26 kHz when the tooth number is
500. Accordingly, the tooth number of the teeth
61 is appropriately selected
from within a range from 500 to 1000. The frequency band of the output signal of
the vehicle wheel speed sensors
7a to
7d is a frequency
band with an order equal to 1 kHz to 5 to 6 kHz, which is the vibration frequency
of brake noise. Thus, it is possible to accurately identify a signal that corresponds
to brake noise from the output signal of the vehicle wheel speed sensors
7a
to
7d.
Next, the procedure of a brake noise detection processing that is executed
by the ECU
3 of the first embodiment will be explained with reference to
the flow chart of FIG.
5.
At
100, the output signal of the respective vehicle speed sensors
7a
to
7d are accepted by the ECU
3. Next, at
102,
waveform shaping of the alternating current signal that is output from the vehicle
wheel speed sensors
7a to
7d (FIG. 3) is performed
so as to execute conversion to a two value pulse signal. Along with this, an average
value of the spacing between the two pulses is calculated at a predetermined sampling
cycle, and the vehicle speed V is calculated from an inverse of the calculated
average value. The calculated vehicle speed V is as shown in the time line graph
of FIG.
6. More specifically, in the case that brake noise is not generated,
the vehicle speed V is almost constant (V
0 in FIG. 6) during a short time
period interval. However, in the case that brake noise is generated, the vehicle
speed V changes in response to generation of rotational variation in the vehicle
wheel rotation in accordance with the frequency of the brake noise (V
1 in
FIG.
6).
At
104, fast Fourier transform (FFT) calculation is performed for the
vehicle
speed V shown in FIG. 6, and a frequency spectrum P of the vehicle speed V is calculated
as shown in FIG.
7. This frequency spectrum P shows a gain peak at a frequency
f
1 that corresponds to the rotational variation of the brake disc rotor
60 in accordance with the brake noise. Accordingly, at
106, if the
gain of the frequency spectrum P has become equal to or more than a predetermined
value Th, it can be determined that brake noise, like brake squeal, is being generated.
On the other hand, in the case that brake noise is not generated, a gain peak is
not shown as indicated by V
0 of FIG. 7, and thus the procedure returns to
processing at
100.
Note that, within the ECU
3, a portion that executes the processing at
104 corresponds to a noise frequency identification portion, and a portion
that executes the processing at
106 corresponds to a noise detection portion.
In the case that brake noise is being generated, a brake control for inhibiting
brake noise is executed at
108. In particular, the drive device
4
executes a known brake control for inhibiting brake noise. More specifically, in
this brake control, control is repeatedly executed in which, based on a control
signal of the ECU
3, the brake force of the vehicle wheel that is generating
brake noise is increased or decreased from a value determined based on the depression
state of the brake pedal
1.
Second Embodiment
Hereinafter, a second embodiment will be explained. A brake noise detection
device of the second embodiment differs from the above described first embodiment
with respect to the processing that corresponds to the noise frequency identification
portion. However, the schematic structural configuration of the second embodiment
is the same as that shown in FIG.
1. Hereinbelow, an explanation will be
given of the flow chart shown in FIG. 8, centering on those sections that are different
from those of the first embodiment.
As shown in FIG. 8, at
200, the respective output signals from the vehicle
wheel speed sensors
7a to
7d are accepted by the ECU
3. Next, at
202, FFT calculation is directly performed for the respective
alternating current signals of the vehicle speed sensors
7a to
7d.
The respective output signals from the vehicle wheel speed sensors
7a
to
7d when brake noise is being generated include a frequency
f
0 that corresponds to an almost constant vehicle speed; and, for example,
two frequencies f
1 and f
2 (f
1<f
0<f
2)
that correspond to the rotational variation (increase or decrease of speed) that
accompanies generation of the brake noise. Accordingly, when FFT calculation is
performed for the respective sensor signals, the frequency spectrum P shows three peaks.
Therefore, at
204 in FIG. 8, the peak (frequency component) of
the frequency f
0 that corresponds to the vehicle speed which is constant
is excluded from the frequency spectrum P, and then, at
206, it can be determined
that brake noise is being generated if the respective gains of the frequencies
f
1 and f
2 that correspond to the rotational variation are equal to
or more than respective predetermined thresholds.
In the second embodiment, within the ECU
3, a portion that executes the
processing at
202 and
204 corresponds to the noise frequency identification
portion, and a portion that executes the processing at
206 corresponds to
the noise detection portion.
In the case that brake noise is being generated, in a similar manner to the above
described first embodiment, the brake control for inhibiting brake noise is executed
at
208.
Third Embodiment
Hereinafter, a third embodiment will be explained. A brake noise detection
device of the present embodiment differs from the brake noise detection device
of the first and second embodiments with respect to the positioning method used
for the vehicle wheel speed sensors.
FIG. 9 is a cross sectional view showing the position of the vehicle wheel speed
sensor of the third embodiment. Note that, FIG. 9 only shows an upper half of one
vehicle axle
8. A hub shaft
9 provided with a brake disk
10
is supported by an axle bearing
13 via a bearing
14. A gear (rotor)
11, which acts as a detected portion, is fixed by a nut
12 to a shaft
end of the hub shaft
9 so as to rotate integrally with a tire, not shown.
First teeth
17, which act as a detected body and of which there are
a predetermined number (from 500 to 1000), are formed at equal distances apart
in a circumferential direction around an external periphery surface of the gear
11. In addition, second teeth
19, of which there are the same number
(500 to 1000) as the first teeth
17, are formed at equal distances apart
in a circumferential direction on a rotating surface
18 of the teeth
11
(to the right side in FIG.
9).
A first detection portion (vehicle wheel speed sensor)
15 that faces the
first teeth
17 at a distance of separation is fixed to an axle carrier
13,
and a second detection portion (vehicle wheel speed sensor)
16 that faces
the second teeth
19 at a distance of separation is also fixed to the axle
carrier
13. The first and second detection portions (vehicle wheel speed
sensors)
16 and
17 are both magnetic pickups, and are respectively
connected to the ECU
3.
The ECU
3, in a similar manner to the first and second embodiments, acts
as a noise frequency identification portion, and identifies the frequency components
that correspond to brake noise from alternating current signals that are output
from the respective vehicle wheel speed sensors
15 and
16 of each
of the vehicle wheels
6a to
6d. It can be determined
that brake noise is being generated when the identified frequency components are
equal to or more than a predetermined value.
It should be noted that when brake noise is being generated, in the brake rotor
that includes the brake disk
10, the gear
11, and the like, swing
of the rotating surface
18 is simultaneously generated along with generation
of variation in the rotation speed, as described above, in accordance with the
brake noise.
With the third embodiment, a signal is generated by rotation of the second teeth
19 that are the detected body disposed on the rotating surface
18
of the gear (rotor)
11 detected by the second detection portion
16.
This signal is output, in a similar manner to that of the first detection portion
15, as an alternating current signal having a frequency f
0 that accords
with the rotation speed of the rotor
11, namely, with the constant vehicle
speed (a rotation speed of the tires) that is superimposed with frequencies f
1,
f
2, and the like, that accord with rotational variation of the gear
11
that varies in accordance with brake noise. Further, an output signal from the
second detection portion
16 is such that a variable signal that accords
with the surface swing of the rotor
11 is superimposed on the variation
in the rotation of the rotor
11 that accompanies the generation of brake
noise. This signal results from the fact that the relative distance between the
rotating surface
18 and the second detection portion
16 vary due
to surface swing of the rotating surface
18, and thus an output voltage
of the second detection portion
16 that accords with this distance variation
changes to become comparatively larger. Accordingly, the variation frequency that
accords with the surface swing is also equal to the frequency that corresponds
to brake noise.
In this manner, according to the third embodiment, the second detection portion
16 detects the signal that accords with the surface swing of the rotor
11,
and thus it is possible to reliably detect brake noise such as brake squeal.
Fourth Embodiment
Hereinafter, a fourth embodiment will be explained. In a brake noise
detection device of the present embodiment as well, the positioning method for
the vehicle wheel speed sensors differs from those of the brake noise detection
device of the first and second embodiments.
FIG. 10 shows the positioning of the vehicle wheel speed sensors of the fourth
embodiment in a plan view of a brake disk
23 and a brake caliper
20
alone. Teeth
24, of which there are predetermined number (from 500 to 1000),
are formed at equal distances apart at predetermined radial positions on a rotating
surface of the brake disk
23. The teeth
24 act as a detected body.
On the other hand, a detection portion
22 that is a magnetic pickup is
provided within the brake caliper
20 and positioned so as not to interfere
with a brake piston
21 that pushes a friction member (not shown) against
the brake disk
23. This detection portion
22 is positioned so as
to face the teeth
24 at a distance of separation, and outputs an alternating
current signal that accords with rotation of the brake disk
23 to the ECU
3.
As is known, when brake noise is generated during braking, coupled self-excited
vibration of the brake disk
23 along with the friction member and the brake
piston (not shown), and the like, is generated.
Accordingly, in the brake noise detection device of the present embodiment,
the detection portion
22 positioned within the brake caliper
20 is
able to detect not only the rotation speed of the brake disk
23, but also
the variation in relative distance between the teeth
24 on the brake disk
23 and the brake caliper
20. Accordingly, it is possible to directly
detect vibration (the variation in relative distance) of the brake caliper
20
that accompanies brake noise. For example, as one case of the generation of noise,
even when just the brake caliper
20 vibrates while the brake disk
23
does not, it is possible to detect vibration of the brake caliper
20 using
the detection portion
22 of the brake noise detection device of the present embodiment.
In this manner, according to the fourth embodiment, it is possible to detect
vibration
of the brake caliper
20, namely, the frequency signal of brake noise, using
the detection portion
22 as a vehicle wheel speed sensor, without having
to provide a special vibration sensor and reliably determine that brake noise is
being generated.
Other Embodiments
In each of the above embodiments, examples were described in which a magnetic
pickup was utilized as the vehicle wheel speed sensor. However, the present invention
is not limited to this, and in particular, a speed sensor that utilizes a Hall
device or a magnetic reluctance element, an optical pickup, or the like, may be
utilized for detection of the rotation speed signal of the rotor.
Further, in each of the above embodiments, examples were described in which,
as the noise frequency identification portion, FFT calculation is performed for
the vehicle wheel speed variation or the magnetic pickup output. However, the present
invention is not limited to this, and a band pass filter that identifies a signal
of a frequency band that corresponds to brake noise may be adopted.
Moreover, in the first embodiment, the vehicle wheel speed V is calculated
by calculation of the ECU
3. However, the vehicle wheel speed may be obtained
as a voltage signal using a frequency-voltage (f-V) conversion circuit, or the like.
In addition, it is possible to configure the actuators
5a to
5d
for brake actuation from a wheel cylinder that utilizes hydraulic fluid braking.
In this case, the drive unit
4 can be an actuator provided with a master
cylinder (not shown) that generates a master cylinder pressure due to depression
of the brake pedal
1, a hydraulic circuit system that carries the master
cylinder pressure to each wheel cylinder, and a normally open solenoid valve and
a normally closed solenoid valve, or the like, that execute ABS control. Further,
in this case, the ECU
3 can generate control signals for these solenoid valves.
While the above description is of the preferred embodiments of the present
invention, it should be appreciated that the invention may be modified, altered,
or varied without deviating from the scope and fair meaning of the following claims.
*
