U.S. patent application number 16/465715 was filed with the patent office on 2020-03-26 for method for controlling a force representative of a parking braking of a vehicle and system thereof.
The applicant listed for this patent is FRENI BREMBO S.P.A.. Invention is credited to ANDREA BUTTI, LUCA CAPPELLETTI, STEFANO DOSSI, CORRADO MANZONI, ALFONSO TARANTINI.
Application Number | 20200094795 16/465715 |
Document ID | / |
Family ID | 58402021 |
Filed Date | 2020-03-26 |
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United States Patent
Application |
20200094795 |
Kind Code |
A1 |
BUTTI; ANDREA ; et
al. |
March 26, 2020 |
METHOD FOR CONTROLLING A FORCE REPRESENTATIVE OF A PARKING BRAKING
OF A VEHICLE AND SYSTEM THEREOF
Abstract
A method for controlling a force representative of a parking
braking of a vehicle, having the steps of: determining, by a data
processing unit, a target value of a force representative of a
parking braking of the vehicle to be applied, by a first brake
caliper, on a first brake disc on the basis of a value of the
gradient of the road on which the vehicle is located; determining,
by the data processing unit, a value of a first force contribution
representative of a service braking of the vehicle applied by a
first hydraulic actuator on the first brake disc; determining, by
the data processing unit, a value of a second force contribution
representative of the parking braking of the vehicle to be applied,
by a second electromechanical actuator, on the first brake disc on
the basis of a target value of a force representative of a parking
braking of the vehicle which can be applied by the first brake
caliper on the first brake disc, and of the determined value of the
first force contribution representative of a service braking of the
vehicle; operating, by the data processing unit, the second
electromechanical actuator to apply the determined value of the
second force contribution representative of the parking braking of
the vehicle on the first brake disc.
Inventors: |
BUTTI; ANDREA; (CURNO,
IT) ; MANZONI; CORRADO; (CURNO, IT) ; DOSSI;
STEFANO; (CURNO, IT) ; TARANTINI; ALFONSO;
(CURNO, IT) ; CAPPELLETTI; LUCA; (CURNO,
IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FRENI BREMBO S.P.A. |
CURNO, BERGAMO |
|
IT |
|
|
Family ID: |
58402021 |
Appl. No.: |
16/465715 |
Filed: |
November 28, 2017 |
PCT Filed: |
November 28, 2017 |
PCT NO: |
PCT/IB2017/057447 |
371 Date: |
May 31, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60T 8/17636 20130101;
B60T 13/746 20130101; B60T 8/3255 20130101; B60T 13/748 20130101;
B60T 8/17 20130101; B60T 8/245 20130101; B60T 8/171 20130101; B60T
8/00 20130101; B60T 2270/30 20130101; B60T 2201/06 20130101; B60T
17/222 20130101; B60T 13/74 20130101; B60T 7/085 20130101; B60T
8/1763 20130101; B60T 1/065 20130101; B60T 2270/10 20130101; B60T
7/045 20130101; B60T 13/12 20130101; B60T 8/17557 20130101; B60T
13/741 20130101; B60T 8/17554 20130101; B60T 11/102 20130101; B60T
8/172 20130101; B60T 13/588 20130101; B60T 13/66 20130101; B60T
17/221 20130101; B60T 2201/04 20130101; B60T 8/17551 20130101; B60T
17/223 20130101; B60T 13/662 20130101; B60T 7/042 20130101; B60T
8/344 20130101; B60T 7/107 20130101 |
International
Class: |
B60T 8/17 20060101
B60T008/17; B60T 1/06 20060101 B60T001/06; B60T 13/58 20060101
B60T013/58; B60T 13/12 20060101 B60T013/12; B60T 13/74 20060101
B60T013/74; B60T 8/171 20060101 B60T008/171; B60T 8/172 20060101
B60T008/172; B60T 13/66 20060101 B60T013/66 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 2, 2016 |
IT |
102016000122392 |
Claims
1-7. (canceled)
8. A method for controlling a force representative of a parking
braking of a vehicle, the vehicle comprising at least one first
wheel and a system for controlling the parking braking of the
vehicle, the system comprising: a first brake disc operatively
associated with said at least one first wheel; a first brake
caliper operatively associated with said at least one first brake
disc, the first brake caliper being configured to apply a force
representative of a parking braking on said first brake disc, said
first brake caliper being adapted to receive a hydraulic pressure
which can be applied by a first hydraulic actuator that can be
operated to apply a first force contribution representative of a
service braking of the vehicle on said first brake disc, said first
brake caliper comprising a second electromechanical actuator, which
can be operated to apply a second force contribution representative
of a parking braking of the vehicle on said first brake disc; a
data processing unit operatively connected to the first brake
caliper; the method comprising steps of: determining, by the data
processing unit, a target value of a force representative of a
parking braking of the vehicle to be applied, by the first brake
caliper, on the first brake disc on the basis of a value of the
gradient of the road on which the vehicle is located; determining,
by the data processing unit, a value of the first force
contribution representative of a service braking of the vehicle
applied by the first hydraulic actuator on the first brake disc;
determining, by the data processing unit, a value of the second
force contribution representative of the parking braking of the
vehicle to be applied, by the second electromechanical actuator, on
the first brake disc on the basis of the target value of a force
representative of a parking braking of the vehicle which can be
applied by the first brake caliper on the first brake disc, and of
the determined value of the first force contribution representative
of a service braking of the vehicle; operating, by the data
processing unit, the second electromechanical actuator to apply a
determined value of the second force contribution representative of
the parking braking of the vehicle on the first brake disc.
9. The method according to claim 8, further comprising the step of
determining, by the data processing unit, the value of the second
force contribution representative of the parking braking of the
vehicle applied by the second electromechanical actuator on the
first brake disc, according to quantities which can be detected by
the data processing unit.
10. The method according to claim 9, further comprising the step of
comparing, by the data processing unit, the determined value of the
second force contribution representative of the parking braking of
the vehicle applied by the second electromechanical actuator on the
first brake disc with the target value of the force representative
of the parking braking of the vehicle which can be applied by the
first brake caliper on the first brake disc.
11. The method according to claim 10, further comprising the step
of controlling, by the data processing unit, the operation of the
second electromechanical actuator on the basis of the result of the
step of comparing.
12. The method according to claim 8, further comprising the step of
determining, by the data processing unit, the value of the gradient
of the road on which the vehicle is located on the basis of a first
electrical signal representative of the longitudinal acceleration
of the vehicle and of a second electrical signal representative of
the angular speed of said at least one first wheel.
13. A system for controlling the parking braking of a vehicle, said
vehicle comprising at least one first wheel, the system comprising:
a first brake disc operatively associated with said at least one
first wheel of the vehicle; a first brake caliper operatively
associated with said at least one first brake disc, the first brake
caliper being configured to apply a force representative of a
parking braking on said first brake disc, said first brake caliper
being adapted to receive a hydraulic pressure applied by a first
hydraulic actuator that can be operated to apply a first force
contribution representative of a service braking of the vehicle on
said first brake disc, said first brake caliper comprising a second
electromechanical actuator that can be operated to apply a second
force contribution representative of a parking braking of the
vehicle on said first brake disc; the system further comprising a
data processing unit operatively connected to the first brake
caliper, the data processing unit being configured to perform the
steps of: determining a target value of a force representative of a
parking braking of the vehicle to be applied, by the first brake
caliper, on the first brake disc on the basis of a value of the
gradient of the road on which the vehicle is located; determining a
value of the first force contribution representative of a service
braking of the vehicle applied by the first hydraulic actuator on
the first brake disc; determining a value of the second force
contribution representative of the parking braking of the vehicle
to be applied, by the second electromechanical actuator, on the
first brake disc on the basis of the target value of a force
representative of a parking braking of the vehicle which can be
applied by the first brake caliper on the first brake disc, and of
the determined value of the first force contribution representative
of a service braking of the vehicle; operating the second
electromechanical actuator to apply a determined value of the
second force contribution representative of the parking braking of
the vehicle on the first brake disc.
14. The system according to claim 13, wherein the data processing
unit is further configured to perform the step of determining the
value of the second force contribution representative of the
parking braking of the vehicle applied by the second
electromechanical actuator on the first brake disc, according to
quantities which can be detected by the data processing unit.
15. The system according to claim 14, wherein the data processing
unit is further configured to compare the determined value of the
second force contribution representative of the parking braking of
the vehicle applied by the second electromechanical actuator on the
first brake disc with the target value of the force representative
of the parking braking of the vehicle which can be applied by the
first brake caliper on the first brake disc.
16. The system according to claim 15, wherein the data processing
unit is further configured to control the operation of the second
electromechanical actuator on the basis of the result of the step
of comparing.
17. The system according to claim 13, wherein the data processing
unit is further configured to determine the value of the gradient
of the road on which the vehicle is located on the basis of a first
electrical signal representative of the longitudinal acceleration
of the vehicle and of a second electrical signal representative of
the angular speed of said at least one first wheel.
18. The system according to claim 13, wherein the vehicle further
comprises at least one second wheel, the system further comprising:
a second brake disc operatively associated with said at least one
second wheel; a second brake caliper operatively associated with
said one second brake disc, the second brake caliper being
configured to apply a force representative of a parking braking of
the vehicle on the second brake disc, the second brake caliper
being adapted to receive a hydraulic pressure which can be applied
by a respective first hydraulic actuator, which can be operated to
apply a second force contribution representative of a service
braking of the vehicle on the second brake disc, the second brake
caliper comprising a respective second electromechanical actuator
that can be operated to apply a second force contribution
representative of a parking braking of the vehicle on the second
brake disc, the data processing unit being operatively connected to
the second brake caliper, the data processing unit being configured
to perform on said at least one second wheel the steps of:
determining a target value of a force representative of a parking
braking of the vehicle to be applied, by the second brake caliper,
on the second brake disc on the basis of a value of the gradient of
the road on which the vehicle is located; determining a value of
the first force contribution representative of a service braking of
the vehicle applied by the first hydraulic actuator on the second
brake disc; determining a value of the second force contribution
representative of the parking braking of the vehicle to be applied,
by the second electromechanical actuator, on the second brake disc
on the basis of the target value of a force representative of a
parking braking of the vehicle which can be applied by the second
brake caliper on the second brake disc, and of the determined value
of the first force contribution representative of a service braking
of the vehicle; operating the second electromechanical actuator to
apply a determined value of the second force contribution
representative of the parking braking of the vehicle on the second
brake disc.
Description
[0001] The present invention relates to a method for controlling a
force representative of a parking braking of a vehicle and to a
system thereof.
[0002] Over the last few years, with the development and spreading
of electric parking systems for vehicles, the rapid spreading of
so-called combined brake calipers within braking systems for
vehicles, has been witnessed.
[0003] Such a type of brake caliper, which is usually installed on
the wheel sides on which the presence of the parking brake is
required, in a single mechanical component, is adapted to receive
an inlet hydraulic pressure which can be applied on a hydraulic
piston inside the brake caliper, for actuating the service braking,
and it further comprises an electromechanical actuator for
actuating the parking braking.
[0004] The hydraulic piston for actuating the service braking is
operated due to the effect of the hydraulic pressure applied within
the service braking system of the vehicle by the driver of the
vehicle by means of the brake pedal or other systems (such as for
example, the ABS system, the ESC system or the i-booster system)
which are responsible for ensuring the stability or the autonomous
driving of the vehicle.
[0005] The electromechanical actuator for actuating the parking
braking instead is operated by an electronic control unit for
controlling the electric parking system of the vehicle upon a
command imparted by the driver of the vehicle or generated in an
automatic manner.
[0006] Thus, the force resulting from the contact between the
combined brake caliper and the brake disc is given by the sum of
the force contribution of the hydraulic pressure generated by the
hydraulic piston (service braking) and the force contribution of
the electromechanical actuator (parking braking).
[0007] This is due to the fact that the combined brake caliper
typically is designed to ensure the mechanical irreversibility of
the force contribution of the electromechanical actuator for the
parking braking. Thus, once the force contribution of the
electromechanical actuator is applied, the force contribution of
the hydraulic pressure generated by the hydraulic piston is not
released when the hydraulic pressure is removed.
[0008] Indeed, according to this manner for controlling the parking
braking, the electromechanical actuator is controlled by the
electronic control unit so as to ensure the force contribution for
actuating the parking braking of the vehicle independently of the
force contribution applied for actuating the service braking.
[0009] This is a drawback because in order to resist with
difficulty to the sum of the force contribution of the hydraulic
pressure generated by the hydraulic piston and of the force
contribution of the electromechanical actuator, the combined brake
caliper necessarily is to be oversized.
[0010] Such an oversizing certainly is a disadvantage because it
results both in an increase of the weight and sizes and inevitably
an increase of the costs of the combined brake caliper and of the
performance of the electromechanical actuator.
[0011] It is the object of the present invention to devise and make
available a method for controlling a force representative of a
parking braking of a vehicle which allows at least partially
obviating the drawbacks indicated above with reference to the known
art.
[0012] Such an object is achieved by a method according to claim
1.
[0013] An object of the present invention is also a system for
controlling a force representative of a parking braking of a
vehicle.
[0014] Further features and advantages of the method and of the
system thereof according to the invention will become apparent from
the following description of preferred embodiments thereof, given
only by way of non-limiting, indicative example, with reference to
the accompanying drawings, in which:
[0015] FIG. 1 shows by means of a block diagram an electronic
system for controlling a force representative of a parking braking
of a vehicle according to one embodiment of the invention;
[0016] FIG. 2 shows by means of a block diagram a method for
controlling a force representative of a parking braking of a
vehicle according to one embodiment of the invention, and
[0017] FIGS. 3 to 5 show by means of respective diagrams the trend
of quantities according to a further embodiment of the
invention.
[0018] With reference to FIG. 1, a system 100 for controlling a
force representative of a parking braking of a vehicle is now
described, hereinafter also only control system or simply system,
according to one embodiment of the present invention.
[0019] It is worth noting that equal or similar elements in the
drawings are indicated with the same reference numbers.
[0020] The vehicle, of which only a portion is schematically shown
in FIG. 1, is indicated as a whole with the reference number
101.
[0021] It is worth noting that the vehicle 101 is for example, a
four-wheel vehicle. However, such a vehicle could also be a two- or
three-wheel motor vehicle or a vehicle with more than four
wheels.
[0022] With reference to the embodiment in FIG. 1, the vehicle 101
comprises at least one first wheel R1 and the system 100 for
controlling a force representative of a parking braking of the
vehicle 101.
[0023] The system 100 comprises a first brake disc DB1 operatively
associated with said at least one first wheel R1.
[0024] The system 100 further comprises a first brake caliper PZ1
operatively associated with said at least one first brake disc
DB1.
[0025] The first brake caliper PZ1 can be operated to apply a force
representative of a parking braking on the first brake disc
DB1.
[0026] In greater detail, the first brake caliper PZ1 is adapted to
receive a hydraulic pressure which can be applied by a first
hydraulic actuator A1 that can be operated to apply a first force
contribution representative of a service braking of the vehicle on
the first brake disc DB1.
[0027] The first hydraulic actuator A1, e.g. a hydraulic piston
(schematically illustrated in FIG. 1), is inside the first brake
caliper PZ1.
[0028] The operation of the first hydraulic actuator A1 may be
obtained by means of the pressure, by the driver of the vehicle
101, of a brake pedal (not shown in FIG. 1) with which the vehicle
101 is provided.
[0029] The first brake caliper PZ1 comprises a second
electromechanical actuator A2 that can be operated to apply a
second force contribution representative of a parking braking of
the vehicle 101 on the first brake disc DB1.
[0030] Thus, the force representative of the parking braking which
can be applied by the first brake caliper DB1 comprises the first
force contribution representative of the service braking of the
vehicle which can be applied by the first hydraulic actuator A1 and
the second force contribution representative of the parking braking
of the vehicle 101 which can be applied by the second
electromechanical actuator A2.
[0031] The system 101 further comprises a data processing unit 102,
for example a microprocessor or a microcontroller, and a respective
storage unit, operatively connected to the first brake caliper
DB1.
[0032] The second electromechanical actuator A2 is operatively
connected to the data processing unit 102.
[0033] In particular, the data processing unit 102 is configured to
operate the second electromechanical actuator A2.
[0034] According to one embodiment, the data processing unit 102 is
configured to operate the second electromechanical actuator A2
following the receipt of a command for operating the parking brake
which can be operated by the driver of the vehicle 101.
[0035] It is worth noting that the command for operating the
parking brake (not shown in FIG. 1) which can be operated by the
driver of the vehicle 101 may be a lever selector or a button.
[0036] According to another embodiment, the data processing unit
102 is configured to operate the second electromechanical actuator
A2 on the basis of an automatic control generated by the data
processing unit 102 itself according to one or more signals
representative of the monitoring of the movement of the vehicle
101, for example a signal representative of the monitoring of the
accelerator pedal, a signal representative of the status of the
thermal engine, and so on.
[0037] Moreover, the data processing unit 102 is configured to
execute a method for controlling a force representative of a
parking braking of the vehicle 101 according to the present
invention, described in detail later.
[0038] To this end, the data processing unit 102 is configured to
load and execute one or more program codes stored in the respective
storage unit in order to execute the steps of the aforesaid
method.
[0039] The storage unit is also configured to store the data
processed by the data processing unit 102 during the execution of
the aforesaid method by the data processing unit 102.
[0040] It is worth noting that the data processing unit 102
preferably is an electronic control unit.
[0041] According to one embodiment, the electronic control unit is
dedicated at least to control the second electromechanical actuator
A2.
[0042] According to a further embodiment, the electronic control
unit is dedicated to control one or more electromechanical
actuators.
[0043] According to a further embodiment, the electronic control
unit may be peripheral and may be operatively connected to a
central electronic control unit (not shown in FIG. 1) with which
the vehicle 101 is provided.
[0044] Returning to FIG. 1, it is worth noting that as already
indicated above, such a drawing only shows a portion of the vehicle
101.
[0045] In particular, for brevity of description, in addition to
the aforesaid system 100, the vehicle 101 is described as
comprising said at least one first wheel R1.
[0046] The at least one first wheel R1 is any one wheel of the
vehicle 101 belonging to the wheel side (front or rear) on which
the parking brake is provided.
[0047] To this end, if the parking brake is provided on the front
side of the vehicle 101, said at least one first wheel R1 could be
the front wheel of the vehicle 101 (right or left, in the case of a
vehicle with four or more wheels).
[0048] If the parking brake were provided on the rear side of the
vehicle 101, said at least one first wheel R1 could be a rear wheel
of the vehicle 101 (right or left, in the case of a vehicle with
four or more wheels).
[0049] It is worth noting that in the event of a vehicle with four
or more wheels, the vehicle 101 further comprises at least one
second wheel (not shown in FIG. 1) operatively connected to the
system 100 for controlling the parking braking of the vehicle
101.
[0050] In this case, the system 100 further comprises a second
brake disc operatively associated with said at least one second
wheel.
[0051] The system 100 further comprises a second brake caliper
operatively associated with said at least one second brake
disc.
[0052] The second brake caliper is entirely similar to the first
brake caliper PZ1 described above, i.e. it is capable of applying a
force representative of a parking braking of the vehicle 101 on the
second brake disc.
[0053] In greater detail, the second brake caliper is adapted to
receive a hydraulic pressure which can be applied by a respective
first hydraulic actuator that can be operated to apply a second
force contribution representative of a service braking of the
vehicle on the second brake disc.
[0054] The second hydraulic actuator, e.g. a hydraulic piston, is
inside the second brake caliper.
[0055] The operation of the second hydraulic actuator may be
obtained by means of the pressure, by the driver of the vehicle
101, of the brake pedal with which the vehicle 101 is provided.
[0056] The second brake caliper comprises a respective second
electromechanical actuator that can be operated to apply a second
force contribution representative of a parking braking of the
vehicle 101 on the second brake disc.
[0057] The second electromechanical actuator of the second brake
caliper is operatively connected to the data processing unit
102.
[0058] Also in this case, the data processing unit 102 is
configured to operate the second electromechanical actuator of the
second brake caliper according to the manners (manual or automatic)
described above with reference to the operation, by the data
processing unit 102, of the second electromechanical actuator A2 of
the first brake caliper PZ1.
[0059] It is also worth noting here that the data processing unit
102 is configured to execute the method for controlling a force
representative of a parking braking of the vehicle 101 also on said
at least one second wheel.
[0060] In particular, in one embodiment, the data processing unit
102 is configured to acquire a first electrical signal
representative of the longitudinal acceleration of the vehicle 101
(for example, by means of the use of a specific sensor, such as an
inertial platform) and a second electrical signal representative of
the angular speed of said at least one first wheel R1 (for example,
by means of the use of a specific sensor installed on the wheel,
preferably on the hub of the wheel).
[0061] Moreover, according to one embodiment, the data processing
unit 102 is configured to continuously detect the hydraulic
pressure in the service braking system of the vehicle 101.
[0062] It is worth noting that the detection of the hydraulic
pressure in the service braking system of the vehicle 101 may be
obtained by means of the use of one or more sensors distributed
within the braking system or by means of the execution, by the data
processing unit 102, of a calculation model based on indirect
information such as the hydraulic pressure inlet to the allocation
system of the brake system and other information.
[0063] Moreover, according to one embodiment, the data processing
unit 102 is configured to detect, by means of specific sensors
installed therein, quantities representative of operating
parameters of the system 100 during the use thereof that can be
used during the execution of the aforesaid method, such as an
electric voltage value of the electric supply battery of the
vehicle 101, an ambient temperature value, a value representative
of the electric voltage and of the electric current of the second
electromechanical actuator A2 of the first brake caliper PZ1.
[0064] It is worth noting that the detection of such quantities may
be obtained by means of using specific sensors installed on the
electronic board comprising the data processing unit 102 (e.g.
electric voltage sensors or electric current sensors) or by means
of using sensors external to the aforesaid electronic board (e.g.
temperature sensors).
[0065] Referring now also to FIG. 2, a method 200 for controlling a
force representative of the parking braking of a vehicle 101 is now
described.
[0066] It is reiterated that the vehicle 101 comprises at least one
first wheel R1 and a system 100 for controlling a force
representative of a parking braking of the vehicle 101.
[0067] The system 101 comprises: [0068] a first brake disc DB1
operatively associated with said at least one first wheel R1;
[0069] a first brake caliper PZ1 operatively associated with said
at least one first brake disc DB1, the first brake caliper DB1
being configured to exert a force representative of a parking
braking of the vehicle 101 on the first brake disc DB1.
[0070] The first brake caliper PZ1 is adapted to receive a
hydraulic pressure which can be applied by a first hydraulic
actuator A1 that can be operated to apply a first force
contribution representative of a service braking of the vehicle on
the first brake disc DB1.
[0071] The first brake caliper PZ1 comprises a second
electromechanical actuator A2 that can be operated to apply a
second force contribution representative of a parking braking of
the vehicle 101 on said first brake disc DB1.
[0072] The system 100 further comprises a data processing unit 102
operatively connected to the first brake caliper DB1.
[0073] With reference to FIG. 2, the method comprises a symbolic
step of starting ST.
[0074] The method 200 further comprises a step of determining 201,
by the data processing unit 102, a target value of a force
representative of a parking braking of the vehicle to be applied,
by the first brake caliper PZ1, on the first brake disc DB1 on the
basis of a value of the gradient of the road on which the vehicle
is located.
[0075] The target value of the force FT representative of a parking
braking may be obtained by using for example, the following
formula:
FT=K*sin(arctan(gradient))
where K is a coefficient whose value depends on the weight of the
vehicle 101, on the effective radius of the brake disc, on the
friction coefficient between pad and brake disc, on the radius of
the wheel.
[0076] In one embodiment, shown with a dotted line in FIG. 2, the
method 200 further comprises a step of determining 202, by the data
processing unit 102, the value of the gradient of the road on which
the vehicle 101 is located on the basis of a first electrical
signal representative of the longitudinal acceleration of the
vehicle 101 and/or of a second electrical signal representative of
the angular speed of said at least one first wheel DB1 acquired by
the data processing unit 102.
[0077] The gradient of the road may be determined for example,
starting from the longitudinal acceleration of the vehicle 101 by
means of the following formula indicated below, or by a
mathematical simplification thereof indicated in the successive
formula (that can be used for small angles):
Gradient = tan ( arcsin ( Acc_long _veic g ) ) or ##EQU00001##
Gradient = tan ( arcsin ( Acc_long _veic g ) ) = arcsin ( Acc_long
_veic g ) = Acc_long _veic g ##EQU00001.2##
where "Acc_long_veic" is the longitudinal acceleration of the
vehicle.
[0078] Returning to the embodiment of FIG. 1, the method 200
further comprises a step of determining 203, by the data processing
unit 102, a value of a first force contribution HF representative
of a service braking of the vehicle 101 applied by the first
hydraulic actuator A1 on the first brake disc DB1.
[0079] It is worth noting that the value of a first force
contribution HF representative of a service braking of the vehicle
101 (hydraulic pressure) may be calculated from a value of
hydraulic pressure detected by a specific pressure sensor by means
of using a mathematical calculation model or estimator using for
example, the following formula:
HF=pressure*Piston_Area
where: "pressure" is the hydraulic pressure detected by the
pressure sensor; "Piston_Area" is the area of the hydraulic
piston.
[0080] The method 200 further comprises a step of determining 204,
by the data processing unit 102, a value of the second force
contribution representative of the parking braking of the vehicle
101 to be applied, by the second electromechanical actuator A2, on
the first brake disc DB1 on the basis of the target value of a
force representative of a parking braking of the vehicle 101, and
of the determined value of the first force contribution
representative of a service braking of the vehicle 101.
[0081] It is worth noting that the value of a second force
contribution EF representative of the parking braking may be
determined for example by means of the following formula:
EF=FT-HF+FM
where: FT is the target value of the force representative of a
parking braking; HF is the value of a first force contribution
representative of a service braking; FM is the force margin due to
the force fall at the removal of the hydraulic pressure.
[0082] It is worth noting that an example of application of such a
formula is shown in FIG. 4.
[0083] It is worth noting that the above-described step of
determining 203 and the step of determining 204 are executed for
example, by the data processing unit 102, in a continuous manner so
as to have the estimate of the determined values always updated
according to the pressure variations and on the basis of the
application step (to this end, see the examples in FIGS. 3 to
5).
[0084] Returning again to the embodiment of FIG. 2, the method 200
further comprises a step of operating 205, by the data processing
unit 102, the second electromechanical actuator A2 to apply the
determined value of the second force contribution representative of
the parking braking of the vehicle 101 on the first brake disc
DB1.
[0085] To this end, the data processing unit 102 is configured to
operate an electric motor (in direct current or in alternating
current) operatively connected to the second electromechanical
actuator A2.
[0086] The force applied by the second electromechanical actuator
A2 may be estimated according to trends of the quantities of
electric voltage and electric current of the electric motor.
[0087] The method 200 comprises a symbolic step of ending ED.
[0088] According to one embodiment (shown with dotted lines in FIG.
2), combined with any one of the ones described above, the method
200 further comprises a step of determining 206, by the data
processing unit 102, a value of the second force contribution
representative of the parking braking of the vehicle 101 applied by
the second electromechanical actuator A2 on the first brake disc
DB1 on the basis of quantities representative of operating
parameters of the system 100 during the use thereof, which can be
detected by the data processing unit 102.
[0089] It is worth noting that such quantities can be detected
through specific sensors.
[0090] It is worth noting that also the step of determining 206 is
executed in a continuous manner to always have an updated
control.
[0091] In this embodiment, the method 200 further comprises a step
of comparing 207, by the data processing unit 102, the determined
value of the second force contribution representative of the
parking braking of the vehicle 101 applied by the second
electromechanical actuator A2 on the first brake disc DB1 with the
target value of the force representative of the parking braking of
the vehicle 101.
[0092] In this embodiment, the method 200 further comprises a step
of controlling 208, by the data processing unit 102, the operation
of the second electromechanical actuator A2 on the basis of the
result of the step of comparing 207.
[0093] In particular, the electric motor (in direct current or in
alternating current) operatively connected to the second
electromechanical actuator A2 is controlled until the determined
value of the second force contribution representative of the
parking braking of the vehicle 101 applied by the second
electromechanical actuator A2 on the first brake disc DB1 does not
coincide with the target value of the force representative of the
parking braking of the vehicle 101.
[0094] With reference to FIGS. 3 to 5, examples of executing the
method 200 for controlling the parking braking of the vehicle 101
are now described.
[0095] Each of the FIGS. 3 to 5 is a Cartesian diagram indicating
time (t) on the abscissas, and on the ordinates, the following
quantities: [0096] HF: value of the first force contribution
representative of the service braking which can be applied by the
first actuator A1 of the first brake caliper PB1 on the first brake
disc DB1; [0097] TF: target value of the force representative of
the parking braking of the vehicle 101 which can be applied by the
first brake caliper PZ1 on the first brake disc DB1; [0098] EF:
value of the second force contribution representative of the
parking braking which can be applied by the second actuator A2 of
the first brake caliper PZ1 on the brake disc DB1; [0099] EPB:
value of the force applied by the first brake caliper PZ1 on the
first brake disc DB1.
[0100] Reference tc in FIGS. 3 to 5 indicates the time instant when
the method 200 for controlling the parking braking of the vehicle
101 according to the present invention is executed, i.e. the
parking brake control is imparted by the driver of the vehicle
101.
[0101] In the example in FIG. 3, the value applied of the first
force contribution HF representative of the service braking
(hydraulic force) of the vehicle 101 is null.
[0102] In this case, the value of the second force contribution EF
representative of the parking braking (electromechanical force) of
the vehicle 101 is determined so as to alone satisfy the target
value TF of the force representative of the parking braking of the
vehicle 101 which can be applied by the first brake caliper PZ1 on
the first brake disc DB1.
[0103] The force EPB representative of the parking braking of the
vehicle 101 applied by the first brake caliper PZ1 on the first
brake disc DB1 corresponds to the value of the second force
contribution EF representative of the parking braking
(electromechanical force) of the vehicle 101.
[0104] In the example in FIG. 4, the value applied of the first
force contribution HF representative of the service braking
(hydraulic force) of the vehicle 101 is not null. In this case, the
value of the second force contribution EF representative of the
parking braking (electromechanical force) of the vehicle 101 is
determined so that the force EPB representative of the parking
braking applied by the first brake caliper PZ1 on the first brake
disc DB1 is equal to the target value TF of the force
representative of the parking braking which can be applied by the
first brake caliper PZ1 on the first brake disc DB1 considering the
non-null value of the first force contribution HF representative of
the service braking (hydraulic force).
[0105] It is worth noting that from the moment when the value of
the first force contribution HF representative of the service
braking becomes null (release of the hydraulic pressure within the
brake system of the vehicle 101), the force EPB representative of
the parking braking applied by the first brake caliper PZ1 on the
first brake disc DB1 corresponds to the target value TF of the
force representative of the parking braking which can be applied by
the first brake caliper PZ1 on the first brake disc DB1.
[0106] This is due to the mechanical features of the brake caliper
which changes its behavior according to the fact that there is
pressure or there is no pressure (deformations and so on).
[0107] Moreover, it may be considered that the value of a second
force contribution EF representative of the parking braking may be
determined for example by means of the above-described formula
EF=FT-HF+FM.
[0108] In the example of FIG. 5, the value applied by the first
force contribution HF representative of the service braking
(hydraulic force) of the vehicle 101 is equal to or greater than
the target value TF of the force representative of the parking
braking of the vehicle 101 which can be applied by the first brake
caliper PZ1 on the first brake disc DB1.
[0109] In this case, the value of the second force contribution EF
representative of the parking braking (electromechanical force) of
the vehicle 101 is determined so as to ensure the mechanical
irreversibility considering the non-null value of the first force
contribution HF representative of the parking braking (hydraulic
force), and to keep the force EPB representative of the parking
braking applied by the first brake caliper PZ1 on the first brake
disc DB1 equal to the target value TF of the force representative
of the parking braking which can be applied by the first brake
caliper PZ1 on the first brake disc DB1 also if the value of the
first force contribution HF representative of the service braking
(hydraulic force) of the vehicle 101 becomes null.
[0110] It is indeed worth noting that from the moment when the
value of the first force contribution HF representative of the
service braking of the vehicle 101 becomes null (release of the
hydraulic pressure within the brake system of the vehicle 101), the
force EPB representative of the parking braking applied by the
first brake caliper DB1 on the first brake disc DB is equal to or
greater than the target value TF of the force representative of the
parking braking which can be applied by the first brake caliper PZ1
on the first brake disc DB1.
[0111] Indeed, once the second electromechanical actuator A2 comes
into contact with the brake pad, the force is not released, due to
the effect of the mechanical irreversibility of the second
electromechanical actuator A2, also once the hydraulic pressure is
released, because the brake pad does not return to the resting
position (the brake pad attempts to move but is blocked by the
second electromechanical actuator A2).
[0112] Thus, once the second electromechanical actuator A2 starts
applying the force, the value of the force applied by the first
brake caliper PZ1 on the first brake disc DB1 may only increase but
cannot decrease.
[0113] It is worth noting that the value of the force applied by
the first brake caliper PZ1 on the first brake disc DB1 naturally
decreases if the second electromechanical actuator A2 is moved in
release direction.
[0114] The method 200 and the system 100 thereof of the present
invention have various advantages.
[0115] Firstly, through the method of the present invention, the
second force contribution representative of the parking braking may
be applied accurately also in the presence of hydraulic pressure,
i.e. also in the presence of the first force contribution
representative of the service braking of the vehicle, without
overloading the mechanical component of the first brake caliper,
thus facilitating the successive step of releasing the parking
braking, therefore reducing the residual torque, also reducing the
consumption of electric power.
[0116] The fact of applying the second force contribution
representative of the parking braking (electromechanical force)
according to the first force contribution representative of the
service braking (hydraulic force due to the hydraulic pressure
within the brake system of the vehicle) allows a minimum overall
force to be obtained at contact between pad (mounted on the first
brake caliper) and first brake disc, which overall force is
required for parking without overloading and therefore oversizing
the mechanical component. Thereby, the weight, the volumes and the
cost of the mechanical components may be significantly reduced, and
more relaxed performance of the electromechanical actuator may be
obtained.
[0117] Moreover, the method of the present invention allows the
second force contribution representative of the parking braking
(electromechanical force) to be applied according to the first
force contribution representative of the service braking (hydraulic
force) already applied so as to reach the target value of force
representative of the parking braking of the vehicle without
inducing an excessive stress from the mechanical viewpoint.
[0118] Those skilled in the art may make several changes and
adaptations to the above-described embodiments of the method and
system thereof, and may replace elements with others which are
functionally equivalent in order to meet contingent needs, without
departing from the scope of the following claims. Each of the
features described as belonging to a possible embodiment may be
achieved irrespective of the other embodiments described.
* * * * *