U.S. patent application number 10/063193 was filed with the patent office on 2003-10-02 for method and apparatus for vehicle regenerative braking.
This patent application is currently assigned to Ford Motor Company. Invention is credited to Worrel, Peter Francis.
Application Number | 20030184153 10/063193 |
Document ID | / |
Family ID | 27803625 |
Filed Date | 2003-10-02 |
United States Patent
Application |
20030184153 |
Kind Code |
A1 |
Worrel, Peter Francis |
October 2, 2003 |
Method and apparatus for vehicle regenerative braking
Abstract
18A method and an apparatus (12) which senses whether a vehicle
(10) is being decelerated by the use of regenerative braking and
which selectively and automatically activates frictional braking
assemblies (60-66) if such regenerative braking has not been
achieved.
Inventors: |
Worrel, Peter Francis;
(Troy, MI) |
Correspondence
Address: |
DYKEMA GOSSETT PLLC
315 EAST EISENHOWER PARKWAY
SUITE 100
ANN ARBOR
MI
48108-3306
US
|
Assignee: |
Ford Motor Company
The American Road
Dearborn
MI
48121
|
Family ID: |
27803625 |
Appl. No.: |
10/063193 |
Filed: |
March 28, 2002 |
Current U.S.
Class: |
303/152 |
Current CPC
Class: |
B60L 2270/145 20130101;
B60L 2260/28 20130101; B60L 7/26 20130101; B60L 2240/507 20130101;
B60L 2240/486 20130101; B60L 50/61 20190201; B60L 2240/465
20130101; Y02T 10/645 20130101; Y02T 10/7072 20130101; Y02T 10/72
20130101; B60L 2240/461 20130101; Y02T 10/7077 20130101; B60L 7/18
20130101; B60L 15/2009 20130101; Y02T 10/62 20130101; Y02T 10/6217
20130101; Y02T 10/7275 20130101; B60L 50/16 20190201; B60L 7/10
20130101; B60L 3/108 20130101; Y02T 10/64 20130101 |
Class at
Publication: |
303/152 |
International
Class: |
B60T 008/64 |
Claims
1. An assembly comprising a selectively energizable frictional
braking assembly; a sensor which determines whether regenerative
braking has been applied to a vehicle and which generates a signal
in the absence of the application of said regenerative braking to
said vehicle; and a controller assembly which is coupled to said
selectively energizable frictional braking assembly and to said
sensor, which receives said signal from said sensor and, in
response to said receipt of said signal from said sensor,
selectively activates said frictional braking assembly, effective
to brake said vehicle.
2. The assembly of claim 1 wherein said sensor comprises a wheel
speed sensor.
3. The assembly of claim 1, wherein said controller further
determines if a certain amount of regenerative braking has occurred
within a certain predetermined amount of time and, in response to a
determination that said certain amount of regenerative braking has
not occurred within said predetermined amount of time, said
controller selectively and automatically activates said frictional
braking assembly, effective to brake said vehicle.
4. The assembly of claim 1 wherein said assembly further comprises
a selectively movable member which is coupled to said controller
and which defines a certain amount of regenerative braking and
which communicates said defined and certain amount of regenerative
braking to said controller.
5. The assembly of claim 4 wherein said selectively movable member
comprises a brake pedal.
6. The assembly of claim 4 wherein said controller stores said
defined certain amount of regenerative braking and compares said
stored amount of regenerative braking with said signal from said
sensor and, based upon said comparison, energizes said frictional
braking assembly.
7. A vehicle comprising at least one wheel which will be
selectively braked; a frictional brake assembly which is
selectively coupled to said at least one wheel; a regenerative
braking assembly; a sensor which measures a speed of said vehicle
and which produces a first signal which is indicative of said
measured speed; a brake request member which selectively generates
a second signal which represents a certain amount of desired
vehicular deceleration; and a controller which is coupled to said
brake request member, to said frictional brake assembly, and to
said speed sensor, said controller receiving said second signal
and, in response to said receipt of said second signal, said
controller attempts to decelerate said vehicle by use of said
regenerative braking assembly, said controller further receiving
said first signal and using said first and second signals to
determine whether said vehicle has been decelerated and, based upon
said determination, selectively brakes said at least one wheel by
use of said frictional brake assembly.
8. The vehicle of claim 7 wherein said regenerative braking
assembly comprises a motor and a battery.
9. The vehicle of claim 7 wherein said frictional braking assembly
comprises a wheel braking portion and a pneumatic control which
selectively causes said wheel braking portion to selectively
decelerate said vehicle.
10. The vehicle of claim 7 wherein said brake request member
comprises a brake pedal.
11. The vehicle of claim 7 wherein said sensor comprises a wheel
speed sensor.
12. A method for braking a vehicle comprising the steps of:
initially attempting to regeneratively brake said vehicle;
determining whether said vehicle has been regeneratively braked;
and automatically causing said vehicle to be frictionally braked if
said vehicle has failed to be regeneratively braked.
13. The method of claim 12 wherein said step of determining whether
said vehicle has been regeneratively braked comprises the steps of
receiving a certain value; creating a second value; and comparing
said second value to said certain value.
14. The method of claim 13 wherein said second value comprises a
sensed amount of deceleration of said vehicle.
15. The method of claim 14 wherein said certain value comprises a
deceleration value which is dependent upon the position of a brake
pedal.
16. The method of claim 12 wherein said method further comprises
the step of providing status information that said vehicle has
failed to be regeneratively braked.
17. The method of claim 12 wherein said vehicle is of the type
having a transmission which outputs torque and wherein said step of
initially attempting to regeneratively brake said vehicle comprises
the step of providing a flywheel assembly; and coupling said
flywheel assembly to said transmission.
18. The method of claim 12 wherein said vehicle is of the type
having at least one wheel and wherein said step of determining
whether said vehicle has been regeneratively braked comprises the
steps of providing a sensor; and coupling said sensor to said at
least one wheel, effective to allow said sensor to generate an
output signal indicative of the speed of said at least one
wheel.
19. The method of claim 18 wherein said step of determining whether
said vehicle has been regeneratively braked further comprises the
step of calculating a certain amount of deceleration of said at
least one wheel.
Description
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] The present invention generally relates to a method and an
apparatus for determining whether a vehicle has been regeneratively
braked and for frictionally braking the vehicle in the event that
the vehicle has not been regeneratively braked and to a vehicle
which incorporates the method and apparatus and more particularly,
to a method and apparatus which measures and/or senses the speed of
a vehicle after a regenerative braking assembly has been activated,
effective to determine whether the vehicle has been regeneratively
braked and, based upon the measured or sensed speed, activates a
frictional brake assembly, effective to brake the vehicle.
[0003] 2. Background of the Invention.
[0004] A vehicle may be braked or selectively decelerated or slowed
by the use of several techniques or strategies. For example, a
hybrid type vehicle may be regeneratively braked by selectively
coupling the torque emanating from the transmission or powertrain
assembly to an energy storage device (e.g., a flywheel assembly),
thereby conserving energy while slowing or decelerating the
vehicle. Some regenerative strategies require that the torque be
converted into electrical energy, by a motor, and then stored
within a battery.
[0005] While such regeneration does desirably slow a vehicle's
velocity or speed, it does not typically provide sufficient
deceleration to actually stop the vehicle. Hence, these
regenerative braking strategies must normally be used in
combination with traditional braking strategies which require the
use of a frictional brake assembly on each of the wheels.
Particularly, a frictional brake assembly selectively engages the
wheel on which it is operatively disposed and, in this manner,
these frictional brake assemblies selectively and cooperatively
decelerate and stop a vehicle.
[0006] There exist a number of unique strategies which utilize such
frictional braking assemblies and which seek to dynamically
distribute the amount of braking between braking assemblies located
at the rear of the vehicle (i.e., behind the driver) and the front
of the vehicle in order to maintain overall vehicular stability.
Typically, the vehicle is initially regeneratively braked in order
to maximize the amount of energy which may be regeneratively stored
and concomitantly decrease the use of the frictional brakes which
wear over time and must be replaced or serviced.
[0007] It is desirable to confirm whether regenerative deceleration
of the vehicle has occurred and/or to confirm that the regenerative
braking system is operable in order to avoid a relatively sudden
application of the frictional brakes which is necessary in order to
achieve the desired vehicular braking. Particularly, such a sudden
application of the frictional brakes both reduces the operating
life of these brakes, provides discomfort and annoyance to the
passengers of the vehicle, and oftentimes prevents a desired brake
distribution to occur. The present method and apparatus provides
this confirmation benefit and provides a strategy which eliminates
or reduces the need to suddenly and fictionally brake a vehicle due
to a failure of the regenerative braking system to supply the
desired braking.
SUMMARY OF INVENTION
[0008] A method and an apparatus is provided for braking a vehicle
which overcomes some or all of the previously delineated drawbacks
of prior braking systems and strategies.
[0009] In accordance with the present invention, an assembly is
provided having a selectively energizable frictional braking
assembly, a sensor which determines whether a certain amount of
regenerative braking has been applied to a vehicle and which
generates a signal in the absence of the sensed application of the
certain amount of regenerative braking to the vehicle, and a
controller assembly which is coupled to the selectively energizable
frictional braking assembly and to the sensor, which receives the
signal from the sensor and, in response to the receipt of the first
signal from the sensor, selectively activates the frictional
braking assembly, effective to provide braking to the vehicle.
[0010] In accordance with another aspect of the present invention,
a vehicle is provided having at least one wheel which will be
selectively braked, a frictional brake assembly which is
selectively coupled to the at least one wheel; a regenerative
braking assembly, a sensor which measures a speed of the vehicle
and which produces a first signal which is indicative of the
measured speed, a brake request member which selectively generates
a second signal which represents a certain amount of desired
vehicular deceleration, and a controller which is coupled to the
brake request member, to the frictional brake assembly, and to the
speed sensor, the controller receiving the second signal and, in
response to the receipt of the second signal attempts to decelerate
the vehicle by use of the regenerative braking assembly, the
controller further receiving the first signal and uses the first
and second signals to determine whether the vehicle has been
decelerated and, based upon the determination, selectively brakes
the at least one wheel by use of the frictional brake assembly.
[0011] In accordance with yet another aspect of the invention, a
method for braking a vehicle is provided having the steps of
initially attempting to regeneratively brake the vehicle;
determining whether the vehicle has been regeneratively braked; and
automatically causing the vehicle to be frictionally braked if the
vehicle has failed to be regeneratively braked.
[0012] These and other features and advantages of the present
invention will become apparent from a reading of the following
detailed description of the preferred embodiment of the invention
and by reference to the following drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a block diagram of a vehicle incorporating the
apparatus of the preferred embodiment of the invention.
DETAILED DESCRIPTION
[0014] Referring now to FIG. 1, there is shown a vehicle 10 which
includes a regenerative braking confirmation assembly 12 which is
made in accordance with the teachings of the preferred embodiment
of the invention.
[0015] Particularly, vehicle 10 includes a torque generator 14,
such as but not limited to an internal combustion engine or fuel
cell assembly, and a transmission assembly 16 which is physically
coupled to the torque generator 14 by a powertrain member 18.
Vehicle 10 further includes a regenerative brake assembly 20 which
comprises a motor 22, a clutch 24, and a battery 26. Particularly,
the clutch 24 is physically coupled to the transmission 16 by the
output shaft 76, and to the motor 22. The motor 22 is electrically
coupled to the battery 26 and the battery 26 may comprise a
conventional vehicular battery.
[0016] Further, the vehicle 10 includes a differential assembly 30
which is physically coupled to the clutch 24 by a powertrain member
32. Moreover, vehicle 10 includes a pair of rear axles or
halfshafts 36, 38 which are each coupled to the differential
assembly 30 and to a respective rear wheel 40, 42. The vehicle 10
also includes a front axle 46 which is coupled to a pair of front
wheels 48, 50, and frame members 54, 56 which are coupled to the
front axle 46. Frame member 54 is further coupled to the rear axle
38 while the frame member 56 is coupled to the rear axle 36.
[0017] Vehicle 10 further includes frictional brake assemblies 60,
62, 64, and 66 which respectively reside upon or in close proximity
to wheels 40, 42, 48, and 50 and which selectively and frictionally
brake these respective wheels 40, 42, 48, and 50, effective to slow
or stop the vehicle 10 (e.g., to brake the vehicle 10), and a
controller 70 which is operable under stored program control and
which is physically and communicatively coupled to the clutch 24
and to the frictional brake assemblies 60-66. Vehicle 10 also
includes a selectively depressible brake request member or brake
pedal 73 which is coupled to the controller 70. That is, controller
70, in one embodiment, forms part of the regenerative braking
confirmation assembly 12 and also provides other vehicular
functions which are set forth below. In other non-limiting
embodiment, a separate controller may be used to provide the
regenerative braking confirmation function of the preferred
embodiment of the invention.
[0018] It should be realized that only the relevant portions of
vehicle 10 are shown within FIG. 1 and described above and that
while the vehicle 10 discloses a rear wheel drive vehicle, the
present invention is applicable to a wide variety of vehicular
architectures, including but not limited to a front wheel drive
vehicle, an all wheel drive vehicle, and/or an on demand drive
vehicle and that nothing in this description is meant to limit the
applicability of the present invention only to the type of vehicle
which is shown in FIG. 1.
[0019] In conventional operation, torque is produced by the torque
generator 14 and is communicated to the transmission 16 by the
drivetrain member 18. The transmission 16 then outputs at least a
portion of the received torque by the use of the output shaft or
member 76 which is coupled to the clutch 24 and to the transmission
16. Typically, the controller 70 controllably causes the clutch 24
to communicate the torque which is output from the transmission 16
(i.e., from the shaft 76) to the differential 30, by the use of
powertrain member 32. The differential 30 then communicates the
torque to the axles 36, 38, effective to allow the wheels 40, 42 to
rotate and to allow the vehicle 10 to be driven.
[0020] When the controller 70 senses a depression of the member 73,
the controller 70 controllably causes the clutch 24 to communicate
the torque emanating from the output member 76 to the motor 22. The
received torque causes the motor 22 to function as a generator and
to communicate the generated electrical energy into the battery 26,
thereby conserving energy (e.g., transforming the received kinetic
energy into electrical energy) while braking or decelerating the
vehicle 10 (e.g., regeneratively braking the vehicle 10). When the
maximum allowable amount of regenerative braking has been achieved
and additional amounts of braking have been requested, the
controller 70 activates the frictional braking assemblies 60-66. It
should be realized that a wide variety of frictional braking
assemblies 60-66 may be employed such as those which are
hydraulically or pneumatically activated and those which are of the
anti-lock type. Moreover, it should be appreciated that a wide
variety of regenerative braking assemblies may be used to replace
the assembly 20, including but not limited to those including a
flywheel which receives torque from the clutch 24, and that nothing
in this description is meant to limit the present invention to use
with a certain type of regenerative braking assembly or frictional
braking assembly.
[0021] Regenerative braking confirmation assembly 12 includes or
makes use of the controller 70. In other non-limiting embodiments,
one or more controllers may be used to perform the functionality
and methodology of the preferred embodiment of the invention.
Nothing in this application is meant to limit the use of the
present invention to a certain type of controller architecture.
Assembly 12 further includes at least one speed sensor 80 which is
coupled to the controller 70 and which is adapted to sense the
speed of the wheel 40 and to communicate the sensed speed to the
controller 70. While a single sensor 80 is shown in FIG. 1, it
should be appreciated that additional numbers of sensors may be
employed in other non-limiting embodiments of the invention on any
or all of the other wheels 42, 48 and 50.
[0022] Hence, according to the teachings of the preferred
embodiment of the invention, when controller 70 causes the clutch
24 to regeneratively brake the vehicle 10, the controller 70
communicates with the at least one speed sensor 80 in order to
ascertain whether the vehicle 10 is decelerating (i.e., whether the
vehicle 10 is being regeneratively braked). If, after some
predetermined period of time, vehicular deceleration is not sensed
(or, in one non-limiting embodiment of the invention, if a certain
predetermined amount of vehicular deceleration is not sensed), the
controller 70 automatically (i.e., without intervention by the user
or operator of the vehicle) causes the frictional braking
assemblies 60-66 to decelerate the vehicle 10, and may provide
status or other types of information to the user/driver indicating
that the desired regenerative braking has not occurred or is not
occurring. In one non-limiting embodiment of the invention, the
vehicle deceleration may be calculated by conventional slip control
equations which utilize the wheel speed which is provided by the at
least one sensor 80. Such a calculation may occur within controller
70. If additional wheel sensors are utilized, these equations are
sequentially and separately applied to the respective wheel speed
data emanating from these other sensors and the controller 70 only
activates the frictional braking assemblies 60-66 if all of the
data (for each wheel 40, 42, 48, 50) shows a lack of deceleration.
The use of such slip control equations is explained within the
paper entitled Comparison of Control Methods for Electric Vehicle
Antilock Braking/Traction Control Systems, which is authored by P.
Khatum, C. M. Bimgham, and P. H. Mellor, which is published by the
Society of Automotive Engines (2001-01-0596) and which is fully and
completely incorporated herein by reference, word for word and
paragraph for paragraph. In another non-limiting embodiment,
discrete positions of the member 73 are calibrated to ascertain the
amount of deceleration which is respectively requested by each
position. This calibrated data (along with the data associated with
the current position of the member 73) is stored within the
controller 70 and is used, by the controller 70, in combination
with the data emanating from the at least one speed sensor 80 to
not only ascertain whether the vehicle 10 is being decelerated, but
to determine whether the requested amount of deceleration has been
achieved. In an alternate embodiment of the invention, the
frictional braking is not applied until it is determined that the
full amount of the requested regenerative braking has not been
applied to the vehicle 10.
[0023] In an alternate embodiment, torque generator 14 may comprise
a reservoir of fluid in combination with a hydraulic pump which is
communicatively coupled to the reservoir and controllably coupled
to the controller 70. In this alternate embodiment, powertrain
member 18 may be replaced by at least one hydraulic conduit and
transmission 16 may be replaced by an assembly which rotates in
response to the receipt of fluid. In operation, upon receipt of
certain signals from the controller 70, the pump in cooperation
with the reservoir will selectively couple the fluid to the
transmission which causes the transmission to hydraulically provide
positive or negative torque to accelerate or decelerate the vehicle
10.
[0024] It is to be understood that the invention is not limited to
the exact construction and method which has been described above,
but that various changes and modifications may be made without
departing from the spirit and the scope of the inventions as are
set forth in the following claims.
* * * * *