U.S. patent application number 14/938959 was filed with the patent office on 2017-03-16 for system and method for controlling impact reduction of electric vehicle.
The applicant listed for this patent is Hyundai Motor Company. Invention is credited to Woocheol Cho.
Application Number | 20170072815 14/938959 |
Document ID | / |
Family ID | 58160628 |
Filed Date | 2017-03-16 |
United States Patent
Application |
20170072815 |
Kind Code |
A1 |
Cho; Woocheol |
March 16, 2017 |
SYSTEM AND METHOD FOR CONTROLLING IMPACT REDUCTION OF ELECTRIC
VEHICLE
Abstract
A system and method for controlling impact reduction of an
electric vehicle can reduce the impact generated while releasing a
P stage of a shift lever on a sloped road. The method and system
utilize a motor as a power source, and the method includes:
determining whether a torque applying condition is satisfied when a
release of the P stage of the shift lever is required on a sloped
road; calculating a torque for impact reduction when the torque
applying condition is satisfied; applying the torque for impact
reduction and controlling anti-jerk to change; stopping applying
the torque for impact reduction when a vehicle speed is greater
than or equal to a predetermined speed; and controlling anti-jerk
to restore when the release of the P stage of the shift lever is
completed.
Inventors: |
Cho; Woocheol; (Daejeon,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hyundai Motor Company |
Seoul |
|
KR |
|
|
Family ID: |
58160628 |
Appl. No.: |
14/938959 |
Filed: |
November 12, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 2530/10 20130101;
Y02T 10/642 20130101; B60L 2270/145 20130101; B60W 10/06 20130101;
B60W 2540/16 20130101; B60Y 2300/181 20130101; B60Y 2300/65
20130101; B60W 2520/10 20130101; B60L 2240/642 20130101; B60Y
2300/30 20130101; B60W 30/18027 20130101; B60W 2050/0024 20130101;
B60W 2510/1005 20130101; Y02T 90/16 20130101; B60W 10/08 20130101;
B60L 2250/26 20130101; Y02T 10/645 20130101; B60Y 2300/60 20130101;
Y02T 10/7275 20130101; B60K 6/48 20130101; Y02T 10/64 20130101;
Y10S 903/93 20130101; Y02T 10/6252 20130101; Y02T 10/7291 20130101;
Y02T 10/6286 20130101; B60W 2552/15 20200201; B60W 30/20 20130101;
B60Y 2200/92 20130101; B60K 6/46 20130101; B60W 10/182 20130101;
B60K 2006/4825 20130101; B60L 2240/423 20130101; B60Y 2300/43
20130101; Y02T 10/72 20130101; B60L 15/20 20130101; B60L 2240/12
20130101; B60L 2250/24 20130101; B60W 2710/083 20130101; Y02T
10/6221 20130101; B60K 6/54 20130101 |
International
Class: |
B60L 15/20 20060101
B60L015/20; B60K 6/46 20060101 B60K006/46; B60K 6/54 20060101
B60K006/54 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 10, 2015 |
KR |
10-2015-0128554 |
Claims
1. A method for controlling impact reduction of an electric vehicle
including a motor as a power source, comprising: determining
whether a torque applying condition is satisfied when a release of
a P stage of a shift lever is required on a sloped road;
calculating a torque for impact reduction when the torque applying
condition is satisfied; applying the torque for impact reduction
and controlling anti-jerk to change; stopping applying the torque
for impact reduction when a vehicle speed is greater than or equal
to a predetermined speed; and controlling anti-jerk to restore when
the release of the P stage of the shift lever is completed.
2. The method of claim 1, wherein the torque for impact reduction
is calculated based on a vehicle weight, a wheel radius, a shift
ratio, and an amount of braking requirement.
3. The method of claim 1, wherein the torque applying condition is
satisfied when an acceleration sensor is not in a malfunction
state, the vehicle speed is less than the predetermined speed, and
the amount of braking requirement is greater than or equal to a
predetermined value.
4. The method of claim 1, wherein the change control of anti-jerk
adjusts an anti-jerk gain and a coefficient of a vibration
component extraction filter according to a degree of road
slope.
5. The method of claim 1, further comprising: when the torque
applying condition is not satisfied, controlling anti-jerk to
change; and controlling anti-jerk to restore when the release of
the P stage of the shift lever is completed.
6. A system for controlling impact reduction of an electric vehicle
including a motor as a power source, comprising: a driving
information detector configured to detect a vehicle speed, a degree
of road slope, a position value of a brake pedal, and a shift lever
of the electric vehicle; and a controller configured to control a
motor torque based on a signal from the driving information
detector, wherein the controller determines whether a torque
applying condition is satisfied when a release of a P stage of the
shift lever is required on a sloped road, calculates a torque for
impact reduction when the torque applying condition is satisfied,
applies the torque for impact reduction, controls anti-jerk to
change, stops applying the torque for impact reduction when a
vehicle speed is greater than or equal to a predetermined speed,
and controls anti-jerk to restore when the release of the P stage
of the shift lever is completed.
7. The system of claim 6, wherein the controller calculates the
torque for impact reduction based on a vehicle weight, a wheel
radius, a shift ratio, and an amount of braking requirement.
8. The system of claim 6, wherein the controller determines that
the torque applying condition is satisfied when an acceleration
sensor is not in a malfunction state, the vehicle speed is less
than the predetermined speed, and the amount of braking requirement
is greater than or equal to a predetermined value.
9. The system of claim 6, wherein the controller controls anti-jerk
to change by adjusting an anti-jerk gain and a coefficient of a
vibration component extraction filter according to the degree of
road slope.
10. The system of claim 6, wherein the controller controls
anti-jerk to change when the torque applying condition is not
satisfied and controls anti-jerk to restore when the release of the
P stage of the shift lever is completed.
11. A non-transitory computer readable medium containing program
instructions executed by a processor, the computer readable medium
comprising: program instructions that determine whether a torque
applying condition is satisfied when a release of a P stage of a
shift lever is required on a sloped road; program instructions that
calculate a torque for impact reduction when the torque applying
condition is satisfied; program instructions that apply the torque
for impact reduction and controlling anti-jerk to change; program
instructions that stop applying the torque for impact reduction
when a vehicle speed is greater than or equal to a predetermined
speed; and program instructions that control anti-jerk to restore
when the release of the P stage of the shift lever is completed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims under 35 U.S.C. .sctn.119(a) the
benefit of Korean Patent Application No. 10-2015-0128554 filed in
the Korean Intellectual Property Office on Sep. 10, 2015, the
entire contents of which are incorporated herein by reference.
BACKGROUND
(a) Field of the Invention
[0002] The present invention relates to a system and a method for
controlling impact reduction of an electric vehicle, more
particularly, to a system and a method for controlling impact
reduction of an electric vehicle that reduces impact generated
while releasing a P stage of a shift lever on a sloped road.
(b) Description of the Related Art
[0003] Generally, environmentally-friendly vehicles such as an
electric vehicle, a fuel cell vehicle and a hybrid electric vehicle
are operated by a driving motor which generates torque by
electrical energy.
[0004] The electric vehicle only uses power of the driving motor
operated by power of a battery. On the contrary, the hybrid
electric vehicle uses power of an internal combustion engine and
power of the driving motor in combination.
[0005] If the electric vehicle is parked on a sloped road, torque
is exerted on the wheel by a vehicle weight, so that a parking
gear, a drive shaft, and a wheel drive shaft are sequentially
distorted and energy is accumulated. Thus, the electric vehicle
generates a momentary impact in accordance with releasing the
accumulated energy. The accumulated energy due to distortion of a
driving system may be increased in proportion to the vehicle weight
and a degree of a road slope, and may cause a serious impact.
[0006] According to a conventional art, hardware systems have been
improved such as a structure change of a parking gear or a parking
sprag in order to reduce the impact. However, there is a limitation
in reducing impact by improving hardware system without reducing
the accumulated energy due to distortion of the driving system,
which is a root cause of the problem. Moreover, the vehicle
provided with a shift by wire (SBW) system uses an actuator of high
torque, so the vehicle weight and the manufacturing cost may be
increased.
[0007] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY
[0008] The present invention provides a system and a method for
controlling impact reduction of an electric vehicle having
advantages of reducing impact generated while releasing a P stage
of a shift lever on a sloped road by applying a torque for impact
reduction and by differentiating anti-jerk control.
[0009] An exemplary embodiment of the present invention provides a
method for controlling impact reduction of an electric vehicle
including a motor as a power source that may includes determining
whether a torque applying condition is satisfied when a release of
a P stage of a shift lever is required on a sloped road;
calculating a torque for impact reduction when the torque applying
condition is satisfied; applying the torque for impact reduction
and controlling anti-jerk to change; stopping applying the torque
for impact reduction when a vehicle speed is greater than or equal
to a predetermined speed; and controlling anti-jerk to restore when
the release of the P stage of the shift lever is completed.
[0010] The torque for impact reduction may be calculated based on a
vehicle weight, a wheel radius, a shift ratio, and an amount of
braking requirement.
[0011] The torque applying condition may be satisfied when an
acceleration sensor is not in a malfunction state, the vehicle
speed is less than the predetermined speed, and the amount of
braking requirement is greater than or equal to a predetermined
value.
[0012] The change control of anti-jerk may adjust an anti-jerk gain
and a coefficient of a vibration component extraction filter
according to a degree of road slope.
[0013] The method may further include controlling anti-jerk to
change; and controlling anti-jerk to restore when the release of
the P stage of the shift lever is completed, when the torque
applying condition is not satisfied.
[0014] Another exemplary embodiment of the present invention
provides a system for controlling impact reduction of an electric
vehicle including a motor as a power source that may include a
driving information detector configured to detect a vehicle speed,
a degree of road slope, a position value of a brake pedal, and a
shift lever of the electric vehicle; and a controller configured to
control a motor torque based on a signal from the driving
information detector, wherein the controller may determine whether
a torque applying condition is satisfied when a release of a P
stage of the shift lever is required on a sloped road, calculate a
torque for impact reduction when the torque applying condition is
satisfied, apply the torque for impact reduction, control anti-jerk
to change, stop applying the torque for impact reduction when a
vehicle speed is greater than or equal to a predetermined speed,
and control anti-jerk to restore when the release of the P stage of
the shift lever is completed.
[0015] The controller may calculate the torque for impact reduction
based on a vehicle weight, a wheel radius, a shift ratio, and an
amount of braking requirement.
[0016] The controller may determine that the torque applying
condition is satisfied when an acceleration sensor is not in a
malfunction state, the vehicle speed is less than the predetermined
speed, and the amount of braking requirement is greater than or
equal to a predetermined value.
[0017] The controller may control anti-jerk to change by adjusting
an anti-jerk gain and a coefficient of a vibration component
extraction filter according to the degree of road slope.
[0018] The controller may control anti-jerk to change when the
torque applying condition is not satisfied and controls anti-jerk
to restore when the release of the P stage of the shift lever is
completed.
[0019] A non-transitory computer readable medium containing program
instructions executed by a processor can include: program
instructions that determine whether a torque applying condition is
satisfied when a release of a P stage of a shift lever is required
on a sloped road; program instructions that calculate a torque for
impact reduction when the torque applying condition is satisfied;
program instructions that apply the torque for impact reduction and
controlling anti-jerk to change; program instructions that stop
applying the torque for impact reduction when a vehicle speed is
greater than or equal to a predetermined speed; and program
instructions that control anti-jerk to restore when the release of
the P stage of the shift lever is completed.
[0020] As described above, according to an exemplary embodiment of
the present invention, impact of the electric vehicle generated
while releasing the P stage on the sloped road can be reduced by
applying the torque for impact reduction to minimize distortion of
the driving system.
[0021] In addition, impact of the electric vehicle can be reduced
by differentiating anti-jerk control in accordance with the degree
of road slope, and the manufacture cost may be decreased in case of
the electric vehicle providing with the SBW system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic block diagram of a system for
controlling impact reduction of an electric vehicle according to an
exemplary embodiment of the present invention.
[0023] FIG. 2 is a flowchart showing a method for controlling
impact reduction of an electric vehicle according to an exemplary
embodiment of the present invention.
[0024] FIG. 3 is a schematic depiction of a force applied to an
electric vehicle on a sloped road in order to calculate a torque
for impact reduction according to an exemplary embodiment of the
present invention.
[0025] FIG. 4(a) is a graph showing a state of an electric vehicle
while releasing a P stage of a shift lever according to a
conventional art, and FIG. 4(b) is a graph showing a state of an
electric vehicle to which a torque for impact reduction is applied
while releasing a P stage of a shift lever according to an
exemplary embodiment of the present invention.
[0026] FIG. 5(a) is a graph showing a state of an electric vehicle
to which anti-jerk is not applied, FIG. 5(b) is a graph showing a
state of an electric vehicle to which anti-jerk is applied
according to a conventional art, and FIG. 5(c) is a graph showing a
state of an electric vehicle to which anti-jerk is applied
according to an exemplary embodiment of the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] It is understood that the term "vehicle" or "vehicular" or
other similar term as used herein is inclusive of motor vehicles in
general such as passenger automobiles including sports utility
vehicles (SUV), buses, trucks, various commercial vehicles,
watercraft including a variety of boats and ships, aircraft, and
the like, and includes hybrid vehicles, electric vehicles, plug-in
hybrid electric vehicles, hydrogen-powered vehicles and other
alternative fuel vehicles (e.g. fuels derived from resources other
than petroleum). As referred to herein, a hybrid vehicle is a
vehicle that has two or more sources of power, for example both
gasoline-powered and electric-powered vehicles.
[0028] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. As
used herein, the term "and/or" includes any and all combinations of
one or more of the associated listed items. Throughout the
specification, unless explicitly described to the contrary, the
word "comprise" and variations such as "comprises" or "comprising"
will be understood to imply the inclusion of stated elements but
not the exclusion of any other elements. In addition, the terms
"unit", "-er", "-or", and "module" described in the specification
mean units for processing at least one function and operation, and
can be implemented by hardware components or software components
and combinations thereof.
[0029] In the following detailed description, only certain
exemplary embodiments of the present invention have been shown and
described, simply by way of illustration. As those skilled in the
art would realize, the described embodiments may be modified in
various different ways, all without departing from the spirit or
scope of the present invention.
[0030] Like reference numerals designate like constituent elements
throughout the specification.
[0031] In the present specification and the claims, it shall be
appreciated that an electric vehicle refers to any vehicle using
electricity as a power source, such as a plug in hybrid electric
vehicle (PHEV) or hybrid electric vehicle (HEV) using electricity
as a part of a power source, as well as an electric vehicle (EV)
using electricity as the entirety of a power source.
[0032] Additionally, it is understood that some of the methods may
be executed by at least one controller. The term controller refers
to a hardware device that includes a memory and a processor
configured to execute one or more steps that should be interpreted
as its algorithmic structure. The memory is configured to store
algorithmic steps and the processor is specifically configured to
execute said algorithmic steps to perform one or more processes
which are described further below.
[0033] Furthermore, the control logic of the present invention may
be embodied as non-transitory computer readable media on a computer
readable medium containing executable program instructions executed
by a processor, a controller, or the like. Examples of computer
readable media include, but are not limited to, ROM, RAM, compact
disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart
cards, and optical data storage devices. The computer readable
recording medium can also be distributed in network coupled
computer systems so that the computer readable media is stored and
executed in a distributed fashion, e.g., by a telematics server or
a controller area network (CAN).
[0034] An exemplary embodiment of the present invention will
hereinafter be described in detail with reference to the
accompanying drawings.
[0035] FIG. 1 is a schematic block diagram of a system for
controlling impact reduction of an electric vehicle according to an
exemplary embodiment of the present invention.
[0036] As shown in FIG. 1, a system for controlling impact
reduction of an electric vehicle according to an exemplary
embodiment of the present invention includes a driving information
detector 10, a controller 20, an inverter 30, a battery 40, an
engine 50, a motor 60 and a transmission 70.
[0037] The driving information detector 10 includes a vehicle speed
sensor 11, an acceleration sensor 12, a brake pedal position sensor
13 and a shift lever sensor 14.
[0038] The vehicle speed sensor 11 detects a speed of the electric
vehicle, and transmits a corresponding signal to the controller 20.
The vehicle speed sensor 11 may be mounted at a wheel of the
electric vehicle.
[0039] The acceleration sensor 12 detects an acceleration of the
electric vehicle, and transmits a corresponding signal to the
controller 20. The controller 20 may detect a degree of a road
slope by using the acceleration sensor 12.
[0040] The brake pedal position sensor (BPS) 13 continuously
detects a position value of a brake pedal and transmits a
monitoring signal to the controller 20. The position value of the
brake pedal may be 100% when the brake pedal is pressed fully, and
the position value of the brake pedal may be 0% when the brake
pedal is not pressed at all.
[0041] The shift lever sensor 14 detects a position of a shift
lever that a driver selects, and transmits a corresponding signal
to the controller 20. The shift lever sensor 14 may include an
inhibitor switch.
[0042] The inverter 30 drives the motor 60 by converting a DC
voltage supplied from the battery 40 into a three-phase alternating
voltage in response to a control signal from the controller 20.
[0043] The inverter 30 is composed of a plurality of power
switching elements, and the power switching elements of the
inverter 30 may each be implemented by any one of an IGBT
(insulated gate bipolar transistor), a MOSFET, a transistor, and a
relay.
[0044] The battery 40 is formed with a plurality of unit cells, and
a high voltage for providing a driving voltage to the motor 60 is
stored in the battery 40. The battery 40 is controlled by a battery
management system (not shown) according to a charging state, and is
prevented from overcharging under a critical voltage or over a
critical voltage. The battery management system may transfer a
charge state of the battery 40 to the controller 20 to enable a
driving and regeneration control of the motor 60 to be
executed.
[0045] The engine 50 which is usually included in a hybrid electric
vehicle outputs power as a power source while turning on based on a
control signal from the controller 20.
[0046] The motor 60 is operated by a three-phase AC voltage applied
from the inverter 30 to generate torque, and operates as a power
generator and supplies regenerative energy to the battery 40 during
coasting.
[0047] The transmission 70 adjusts a shift ratio by operating
engagement elements and disengagement elements, using hydraulic
pressure according to a control signal from the controller 20.
[0048] If the engine 50 is included in the electric vehicle, the
engine clutch (not shown) may be disposed between the engine 50 and
the driving motor 60 so that it provides an EV mode and an HEV
mode.
[0049] The controller 20 determines whether a torque applying
condition is satisfied when a release of a P stage (parking stage)
of the shift lever is required on a sloped road, calculates and
applies a torque for impact reduction when the torque applying
condition is satisfied, and controls anti-jerk to change
[0050] In addition, after changing anti-jerk, the controller 20
stops applying the torque for impact reduction when a vehicle speed
is greater than or equal to a predetermined speed, and controls
anti-jerk to restore when the release of the P stage of the shift
lever is completed.
[0051] The controller 20 controls anti-jerk to change without
applying the torque for impact reduction when the torque applying
condition is not satisfied, and controls anti-jerk to restore when
the release of the P stage of the shift lever is completed.
[0052] Therefore, torque for impact reduction may be applied to
minimize distortion of a driving system which is generated while
releasing the P stage of the shift lever on the sloped road, and
anti-jerk may be controlled by differentiating due to the degree of
the road slope.
[0053] To this end, the controller 20 may be implemented as at
least one processor that is operated by a predetermined program,
and the predetermined program may be programmed in order to perform
each step of a method for controlling impact reduction of an
electric vehicle according to an exemplary embodiment of the
present invention.
[0054] Various embodiments described herein may be implemented
within a recording medium that may be read by a computer or a
similar device by using software, hardware, or a combination
thereof, for example.
[0055] According to hardware implementation, the embodiments
described herein may be implemented by using at least one of
application specific integrated circuits (ASICs), digital signal
processors (DSPs), digital signal processing devices (DSPDs),
programmable logic devices (PLDs), field programmable gate arrays
(FPGAs), processors, controllers, micro-controllers,
microprocessors, and electric units designed to perform any other
functions.
[0056] According to software implementation, embodiments such as
procedures and functions described in the present embodiments may
be implemented by separate software modules. Each of the software
modules may perform one or more functions and operations described
in the present invention. A software code may be implemented by a
software application written in an appropriate program
language.
[0057] Hereinafter, a method for controlling impact reduction of an
electric vehicle according to an exemplary embodiment of the
present invention will be described in detail with reference to
FIG. 2 to FIG. 5.
[0058] FIG. 2 is a flowchart showing a method for controlling
impact reduction of an electric vehicle according to an exemplary
embodiment of the present invention.
[0059] As shown in FIG. 2, a method for controlling impact
reduction of an electric vehicle according to an exemplary
embodiment of the present invention starts with detecting driving
information for reducing impact of the electric vehicle at step
S100.
[0060] The controller 20 determines whether a release of a P stage
(parking stage) of a shift lever is required on a sloped road based
on the driving information detected at the step S100 at step
S110.
[0061] When the release of the P stage of the shift lever is
required on the sloped at the step S110, the controller 20
determines whether a torque applying condition is satisfied at step
S120.
[0062] The torque applying condition is satisfied when an
acceleration sensor 12 is not in a malfunction state, a vehicle
speed is less than a predetermined speed, and an amount of braking
requirement is greater than or equal to a predetermined value.
[0063] If the acceleration sensor 12 is out of order
(malfunctioned), a degree of a road slope of the electric vehicle
is not detected, so the torque applying condition is determined to
be satisfied when the acceleration sensor 12 has not
malfunctioned.
[0064] In case that the vehicle speed is less than the
predetermined speed, it may mean that the electric vehicle has
stopped. That is, the predetermined speed may be 0 (zero).
[0065] If the amount of braking requirement is greater than or
equal to the predetermined value, sudden acceleration which may
occur when applying a wrong torque in accordance with an error of
detecting the degree of the road slope can be prevented because a
position value of a brake pedal is greater than or equal to the
predetermined value. That is, the predetermined value may be
determined according to the degree of the road slope and a size of
the torque for impact reduction.
[0066] Herein, if a type of the shift lever is a gate type or a
shift by wire (SBW) type, the torque applying condition may be
determined to be satisfied when the shift lever is the P stage and
a brake is operating. On the contrary, if the type of the shift
lever is a line type, the torque applying condition may be
determined to be satisfied when the shift lever is the P stage, the
brake is operating, and an operation button of the shift lever is
turned on.
[0067] When the torque applying condition is satisfied at the step
S120, the controller 20 calculates the torque for impact reduction
at step S130.
[0068] The torque for impact reduction may be calculated based on a
vehicle weight, a wheel radius, a shift ratio, and an amount of
braking requirement.
[0069] FIG. 3 is a drawing describing force applied to an electric
vehicle on a sloped road in order to calculate a torque for impact
reduction according to an exemplary embodiment of the present
invention.
[0070] In case that the electric vehicle of which a weight is m
stops on the sloped road of which an angle is .theta., a
gravitational force of the electric vehicle F1 is m*g*sin .theta.
[N] (g denotes a gravity acceleration).
[0071] At this time, the electric vehicle is thrust backward or
forward by the force F1 when the P stage of the shift lever is
released. Thus, the force F1 may cause distortion of a driving
system of the electric vehicle such as a parking gear, a drive
shaft, and a wheel drive shaft because the parking gear and a sprag
are engaged.
[0072] A size of distortion of the driving system may be calculated
by multiplying the force F1 by a wheel radius of the electric
vehicle. In addition, the size of distortion changed to torque unit
may be calculated by the following equation.
F2=F1*wheel radius/shift ratio=m*g*sin .theta.*wheel radius/shift
ratio [Nm]
[0073] Herein, m denotes is a weight of the electric vehicle, g
denotes a gravity acceleration, and .theta. denotes an angle of the
sloped road. Also, a deceleration ratio may be used instead of the
shift ratio.
[0074] Therefore, if the torque F2 is applied to the motor of the
electric vehicle while releasing the P stage of the shift lever on
the sloped road, impact due to distortion of the driving system can
be reduced.
[0075] When the torque for impact reduction is calculated at the
step S130, the controller 20 applies the calculated torque for
impact reduction and controls anti-jerk to change at step S140.
[0076] If the controller 20 may correctly know the weight of the
electric vehicle and the degree of road slope, the impact generated
while releasing the P stage can be minimized by applying the
calculated torque for impact reduction. However, the degree of road
slope detected on the basis of the acceleration sensor may have an
error, and the weight of the electric vehicle may be changed by a
number of passengers or an amount of baggage. Thus, there is a
limitation to reduce impact by only applying the torque for impact
reduction. Moreover, if the torque for impact reduction is
excessively applied before the release of the P stage of the shift
lever is completed, durability of the sprag may be
deteriorated.
[0077] Accordingly, the controller 20 may minimize the impact
generated while releasing the P stage by adjusting an anti-jerk
gain and a coefficient of a vibration component extraction filter
according to the degree of road slope.
[0078] The anti-jerk gain may be mapped as a value in the range of
0 to 1 based on a maximum torque of anti-jerk, a minimum torque of
anti-jerk, a model speed filter, and a vibration component
extraction filter.
[0079] After that, the controller 20 compares a vehicle speed with
a predetermined speed at step S160.
[0080] When the vehicle speed is greater than or equal to the
predetermined speed at the step S160, the controller 20 stops
applying the torque for impact reduction at step S170.
[0081] When the applying of the torque for impact reduction is
stopped at the step S170, the controller 20 determines whether the
release of the P stage of the shift lever is completed at step
S180, and controls anti-jerk to restore when the release of the P
stage of the shift lever is completed at step S190.
[0082] On the contrary, when the torque applying condition is not
satisfied at the step S120, the controller 20 controls anti-jerk to
change without applying the torque for impact reduction at step
S150.
[0083] After that, the controller 20 proceeds the process to the
step S180 to determine whether the release of the P stage of the
shift lever is completed, and controls anti-jerk to restore when
the release of the P stage of the shift lever is completed at step
S190.
[0084] FIG. 4(a) is a drawing showing a state of an electric
vehicle while releasing a P stage of a shift lever according to a
conventional art, and FIG. 4(b) is a drawing showing a state of an
electric vehicle to which a torque for impact reduction is applied
while releasing a P stage of a shift lever according to an
exemplary embodiment of the present invention.
[0085] As shown in FIG. 4(a), a vehicle acceleration and a motor
speed of the electric vehicle are sharply changed while releasing
the P stage according to the conventional art, thereby generating
impact.
[0086] On the other hand, as shown in FIG. 4(b), since the torque
for impact reduction is applied according to an exemplary
embodiment of the present invention, the vehicle acceleration and
the motor speed of the electric vehicle are constantly
maintained.
[0087] FIG. 5(a) is a drawing showing a state of an electric
vehicle to which anti-jerk is not applied, FIG. 5(b) is a drawing
showing a state of an electric vehicle to which anti-jerk is
applied according to a conventional art, and FIG. 5(c) is a drawing
showing a state of an electric vehicle to which anti-jerk is
applied according to an exemplary embodiment of the present
invention.
[0088] As shown in FIG. 5(a), a strong vibration may be generated
when anti-jerk is not applied to the electric vehicle. Moreover, as
shown in FIG. 5(b), even though anti-jerk according to a
conventional art is applied to the electric vehicle, a weak
vibration may be still generated. However, as shown in FIG. 5(c),
when anti-jerk according to an exemplary embodiment of the present
invention is applied to the electric vehicle, vibration of the
electric vehicle may be minimized
[0089] As described above, according to an exemplary embodiment of
the present invention, impact generated while releasing the P stage
on the sloped road can be reduced by applying the torque for impact
reduction to minimize distortion of the driving system and by
differentiating anti-jerk control in accordance with the degree of
road slope.
[0090] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments. On the contrary, it is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
[0091] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *