U.S. patent application number 14/077600 was filed with the patent office on 2015-05-14 for active front steering system lock.
This patent application is currently assigned to Ford Global Technologies, LLC. The applicant listed for this patent is Ford Global Technologies, LLC. Invention is credited to Joshua Guerra, Oliver Nehls, Jeremy Alan Rawlings, Lodewijk Wijffels.
Application Number | 20150129344 14/077600 |
Document ID | / |
Family ID | 53042763 |
Filed Date | 2015-05-14 |
United States Patent
Application |
20150129344 |
Kind Code |
A1 |
Nehls; Oliver ; et
al. |
May 14, 2015 |
ACTIVE FRONT STEERING SYSTEM LOCK
Abstract
A vehicle including an active front steer system including a
locking mechanism having a solenoid actuated locking pin and a
spring for biasing the pin toward an extended or locked position
for engaging a locking disc of the active front steer system
wherein the active front steer system further includes a current
sensor for sensing the motion of the pin of the solenoid when the
engine of the vehicle is shut down and pulse width modulated
current to the solenoid is reduced and when the pin movement is
sensed, the pulse width modulated current is increased (fed forward
duty cycle) to reduce the movement of the pin to reduce the noise
made when the metal pin makes when contacting the metal locking
disc. The end of the pin and/or the locking disc may also include
an insulating material to further reduce any remaining noise made
when the metal pin makes when contacting the metal locking
disc.
Inventors: |
Nehls; Oliver; (Canton,
MI) ; Rawlings; Jeremy Alan; (Canton, MI) ;
Guerra; Joshua; (Beverly Hills, MI) ; Wijffels;
Lodewijk; (Canton, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Global Technologies, LLC |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Global Technologies,
LLC
Dearborn
MI
|
Family ID: |
53042763 |
Appl. No.: |
14/077600 |
Filed: |
November 12, 2013 |
Current U.S.
Class: |
180/287 |
Current CPC
Class: |
B60R 25/02156 20130101;
B62D 5/008 20130101 |
Class at
Publication: |
180/287 |
International
Class: |
B60R 25/0215 20060101
B60R025/0215; B62D 5/00 20060101 B62D005/00 |
Claims
1. A vehicle, comprising: a. a steering wheel for driving the
vehicle; b. a steering column including a steering gear input
shaft, the steering column for receiving an input from the steering
wheel and transferring the input to the steering wheels of the
vehicle; c. an active front steer system for adding and subtracting
angle between the steering wheel and the steering gear input shaft,
the active front steer system comprising: i. a solenoid including a
pin, a solenoid coil surrounding at least a portion of the pin for
electromagnetically controlling the position of the pin; a spring
for biasing the pin in a first direction; ii. a locking disc
including a recess for receiving the pin for locking the active
front steer system; iii. a control unit for supplying a
controllable pulse-width modulated current to the solenoid coil of
the solenoid; and iv. a current sensor for detecting the current in
the solenoid coil during vehicle shutdown, the current sensor
detecting the movement of the pin of the solenoid when the control
unit reduces the pulse-width modulated current being supplied to
the solenoid coil when the vehicle is shut down; and d. wherein
after the control unit receives the signal indicating the movement
of the pin during shut down of the vehicle, the control unit
increases the pulse-width modulated current to the solenoid coil of
the solenoid for the purpose of reducing the noise resulting from
the pin contacting the locking disc.
2. The vehicle of claim 1 wherein the end of the pin includes an
insulating material.
3. The vehicle of claim 1 wherein the recess of the locking disc
includes an insulating material.
4. An active front steering system, comprising: a. an active front
steer system for adding and subtracting angle between a steering
wheel and a steering gear input shaft for a vehicle, the active
front steer system comprising: i. a solenoid including a pin, a
solenoid coil surrounding at least a portion of the pin for
electromagnetically controlling the position of the pin; a spring
for biasing the pin in a first direction; ii. a locking disc
including a recess for receiving the pin for locking the active
front steer system; iii. a control unit for supplying a
controllable pulse-width modulated current to the solenoid coil of
the solenoid; and iv. a current sensor for detecting the current in
the solenoid coil during vehicle shutdown, the current sensor
detecting the movement of the pin of the solenoid when the control
unit reduces the pulse-width modulated current being supplied to
the solenoid coil when the vehicle is shut down; and b. wherein
after the control unit receives the signal indicating the movement
of the pin during shut down of the vehicle, the control unit
increases the pulse-width modulated current to the solenoid coil of
the solenoid for the purpose of reducing the noise resulting from
the pin contacting the locking disc.
5. The active front steer system of claim 4 wherein the end of the
pin includes an insulating material.
6. The active front steer system of claim 4 wherein the recess of
the locking disc includes an insulating material.
Description
BACKGROUND
[0001] It is generally known to provide a vehicle including an
active front steering system and including a solenoid for locking
the front steering system. It is also generally known to provide a
vehicle including a locking solenoid of an active front steering
system that makes an objectionable "click" noise every time the
vehicle is shut down. The active front steering (AFS) system may
add and subtract angle between the driver steering wheel input and
the steering gear input shaft. The active front steering system
consists of an electronic control unit (ECU), a motor, a gear and a
locking device all integrated into the steering wheel. The locking
unit may provide a mechanical connection between the steering wheel
and wheels during power-off of the AFS system (i.e., before and/or
after shutting down the engine) and it may provide a means to lock
the actuator in case of a severe failure in the AFS system. The
locking unit may include a solenoid attached to the steering wheel
armature, a pin having a spring for biasing the pin in a direction
toward a locked position and a locking disc connected to the motor
shaft, the disc including pockets or spaces for receiving the end
of the pin and for locking the AFS system.
[0002] The active front steering (AFS) system can add and subtract
angle between the driver steering wheel input and the steering gear
input shaft. In one known embodiment, the AFS system consists of an
electronic control unit (ECU), a motor, a gear and a locking device
all integrated into the steering wheel. The locking unit may
provide a mechanical connection between the steering wheel and the
wheels of the vehicle during power-off of the system (i.e., after
shutting down of the engine). The locking unit may also provide a
lock of the AFS system in case of a severe failure in the AFS
system or some other input.
[0003] While it is known to use a solenoid and locking pin as a
lock actuator for an AFS system, it generates objectionable noise
when contacting the locking disc. When the current is removed from
the solenoid coil, the solenoid pin begins to accelerate from the
force of the coil spring of the solenoid which biases the locking
pin toward the locked position. When the moving solenoid pin makes
contact with the lock plate, an objectionable "click" noise or
sound is produced. In one known application, the locking solenoid
of the active front steering system makes a noise every time the
vehicle is shut down. Despite this long known problem with such
systems, there remains a very significant need for an effective
solution to eliminate the noise of such systems and yet be operable
in the unique operating environment of the AFS system.
DRAWINGS
[0004] FIG. 1 is a graphic view of a vehicle including an active
front steering (AFS) system including a quiet operating AFS lock
according to an exemplary embodiment of the present disclosure.
[0005] FIG. 2 is a partial, perspective graphic view of the AFS
system components of the vehicle of FIG. 1.
[0006] FIG. 3 is a partial graphic view of the AFS lock and
solenoid components of the AFS system of the vehicle of FIG. 1.
[0007] FIG. 4 is a graph of the known current control duty cycle
versus time and the measured current versus time during shutdown
according to the AFS system of the vehicle of FIG. 1.
[0008] FIG. 5 is a graph of the current control duty cycle versus
time and the measured current versus time during shutdown to the
AFS system of the vehicle of FIG. 1.
DETAILED DESCRIPTION
[0009] To meet certain customer, industry and regulatory
requirements for passenger vehicles, automotive manufacturers are
challenged to design vehicles using understood and predictable
methods and materials. In one exemplary embodiment of the present
disclosure, there is disclosed a vehicle 1 including an active
front steering (AFS) system 200. The vehicle may further include a
steering wheel 21 and a steering column 22 for adjusting the
direction of the front wheels of the vehicle 1. The AFS system 200
can add and subtract angle between the operator's input to the
driver steering wheel 21 and the steering column 22 to provide
various affects to driving.
[0010] In an exemplary embodiment of the present disclosure, the
active front steering system 200 may also include an electronic
control unit 65 (ECU) that may be dedicated to controlling the AFS
system 200. In an alternate exemplary embodiment of the present
disclosure, the AFS system 200 may include an engine control module
75 (or other control module of the vehicle) that may include the
ECU 65 or may alternatively provide the function of the ECU 65 such
that it is unitary with the engine control module 75, as best shown
in FIG. 3. In an exemplary embodiment of the present disclosure,
the active front steering system 200 may also include a motor 85
coupled to rotate a gear 95 for providing the AFS system 200 input
to the steering column 22.
[0011] The AFS system 200 may include a locking unit solenoid 210
for locking the AFS system upon shutdown of the vehicle 1. In one
exemplary embodiment, the AFS system 200 may include a solenoid 220
attached to a steering wheel armature 23. For locking the AFS
system 200, a pin 221 has an end extending from the armature 23 and
aligned with a locking disc 224 of the system 200, which disc is
operated by rotation by a motor shaft 223 operated by the motor 85.
The pin 221 is biased toward the locked position (as best shown in
FIG. 3) by a spring 226 constantly biases the pin 221 so the end of
the pin 221 is located in a recess of pocket 225 of the disc
224.
[0012] The AFS system 200 includes a locking solenoid 210 including
a solenoid coil 220 for controlling the location of the pin 221
against the force of the spring 226 using a pulse width modulation
(PWM) signal 66 generated by the ECU 65 of the AFS system 200.
[0013] In one exemplary embodiment of the present disclosure, the
AFS system 200 may include a current sensor 67 for monitoring the
current of the solenoid coil 220 of the solenoid 210. The current
sensor 67 produces a signal that is connected to the ECU 65 (or
alternatively the module 75) that provides effective feedback to
the ECU 65 for determining movement of the pin 221 during a
shutdown of the AFS system 200, such as during shutdown of the
vehicle 1.
[0014] During normal AFS operation, the pin 221 may be retracted
into the locking solenoid 210 when the ECU 65 of the AFS system 200
supplies the PWM signal 66 to the solenoid coil 220 which may use
supplied power (not shown) to generate a magnetic force that
overcomes the spring force of the spring 226 acting on the pin 221
and locating the end of the pin 221 in the recess 225.
[0015] In one exemplary embodiment of the present disclosure, the
AFS system 200 may include a PWM signal 66 having a duty cycle
between 0 and 1 where a 0 duty cycle has no current and a duty
cycle of 1 has means the PWM current signal 66 is always on to the
solenoid coil 220. To unlock the AFS system 200, the ECU controller
65 (or alternatively the ECM 75) adjusts the PWM signal 66 to have
a duty cycle of 1 applied to the solenoid coil 220 for
approximately between 300 and 500 milliseconds to insure the pin
221 is fully retracted from the recess 225 of the locking disc 224.
After the AFS system 200 is unlocked, to maintain the pin 221
retracted in the locking solenoid 210 and the AFS system 200 in an
unlocked state, the ECU controller 65 adjusts the PWM signal 66 to
have a duty cycle of approximately 0.4 (+/-0.1) while the vehicle 1
is operational (i.e., the engine of the vehicle 1 is not shut
down), which particular duty cycle may vary depending upon the
particular specifications of the solenoid 210. As should be
understood, the above is accomplished using a current control loop
(meaning the current applied to the solenoid coil 220 is controlled
by adjusting the PWM signal 66 accordingly), as the PWM signal 66
needed to maintain the pin 221 in an unlocked position may change
with variations in temperature. It should be understood that the
above duty cycle numbers are specific for a given solenoid 210,
including its associated voltage (not shown), although the numbers
give (from a shape point of view) a good general approximation for
other solenoids as well.
[0016] Referring in particular to FIG. 4, it may be observed on the
graph, that upon shutdown of the vehicle 1, the ECU 65 begins
ramping down the PWM current signal or duty cycle 66 being supplied
to the solenoid coil 220 toward zero and thereby reduces the
magnetic force biasing the pin 221 in the unlocked position against
the spring force of the spring 226. When this occurs, when the
magnetic force of the solenoid coil 220 is sufficiently reduced to
substantially match the biasing force of the spring 226, the pin
221 will accelerate and begin to move under the biasing force of
the spring 226 from the open position and toward the closed or
locked position. When the end of the pin 221 is in the recess or
pocket 225 of the locking disc 224, the AFS system 200 is
mechanically locked as best shown in FIG. 3.
[0017] In one exemplary embodiment of the present disclosure, the
AFS system 200 is controlled using the ECU 65 to ramp down the PWM
duty cycle at a rate of approximately fifty percent (50%) or
instead of immediately shutting off the PWM signal as best shown in
FIG. 4. As the PWM current signal 66 to the solenoid coil 220 is
ramped down, the current sensor 67 is used to monitor the current
in the locking system solenoid 210 and provides the detected
current information to the ECU 65 to identify the point in time
when the pin 221 begins to move from the open position and toward
the closed position. The movement of the pin 221 may be seen as a
short "spike" in the measured current detected by the current
sensor 67 as best shown in the charts of FIGS. 4 and 5. The current
spike is created by the movement of the pin 221 through the
magnetic field of the solenoid coil 220 under the biasing force of
the spring 226.
[0018] In one exemplary embodiment of the present disclosure, upon
the sensing of the movement of the pin 221 as represented by the
spike in the detected current from the current sensor 67, the PWM
current signal 66 is immediately increased to increase the PWM duty
cycle back toward 1, and to increase the current supplied to the
solenoid coil 220, at a rate of between approximately sixty-six
percent (66%) and eighty percent (80%) for a period of
approximately one hundred (100) milliseconds, to temporarily
generate an additional magnetic counter force in the solenoid coil
220 of the locking solenoid 210 of the AFS system 200 to cause the
locking pin 221 to decelerate before the end of the pin 221 lands
in the recess 225 of the locking disc 224 thereby reducing, if not
eliminating, the noise typically associated with the end of the
metal pin 221 contacting the metal locking disc 224. It should be
appreciated that it is possible to use a lookup table for defining
the various PWM signal 66 settings mentioned herein for operating
the locking solenoid 210 to obtain the quiet function features of
the present invention. It should be further appreciated that the
lookup table settings may be adjusted using the current sensor 67
feedback until the locking solenoid 210 is correctly decelerated to
obtain the quiet function features of the present invention.
[0019] In one alternate exemplary embodiment of the present
disclosure, in addition to the improved AFS locking system 200 and
its improved locking unit 210, a sound-deadening or insulating
material 230 (as shown in FIG. 3), such as a rubberized coating,
may be incorporated or applied on any or all of the recess 225, the
locking disc 224 and/or the end of the pin 221 to further reduce
the noise of the locking unit of the AFS system 200.
[0020] Any numerical values recited herein or in the figures are
intended to include all values from the lower value to the upper
value in increments of one unit provided that there is a separation
of at least 2 units between any lower value and any higher value.
As an example, if it is stated that the amount of a component or a
value of a process variable such as, for example, temperature,
pressure, time and the like is, for example, from 1 to 90,
preferably from 20 to 80, more preferably from 30 to 70, it is
intended that values such as 15 to 85, 22 to 68, 43 to 51, 30 to 32
etc. are expressly enumerated in this specification. For values
which are less than one, one unit is considered to be 0.00011,
0,001, 0.01 or 0.1 as appropriate. These are only examples of what
is specifically intended and all possible combinations of numerical
values between the lowest value and the highest value enumerated
are to be considered to be expressly stated in this application in
a similar manner. As can be seen, the teaching of amounts expressed
as "parts by weight" herein also contemplates the same ranges
expressed in terms of percent by weight. Thus, an expression in the
Detailed Description of the Invention of a range in terms of at
"`x` parts by weight of the resulting polymeric blend composition"
also contemplates a teaching of ranges of same recited amount of
"x" in percent by weight of the resulting polymeric blend
composition."
[0021] Unless expressly stated, all ranges are intended to include
both endpoints and all numbers between the endpoints. The use of
"about" or "approximately" in connection with a range applies to
both ends of the range. Thus, "about 20 to 30" is intended to cover
"about 20 to about 30", inclusive of at least the specified
endpoints.
[0022] The use of the term "consisting essentially of" to describe
a combination shall include the elements, ingredients, components
or steps identified, and such other elements ingredients,
components or steps that do not materially affect the basic and
novel characteristics of the combination. The use of the terms
"comprising" or "including" to describe combinations of elements,
ingredients, components or steps herein also contemplates
embodiments that consist essentially of the elements, ingredients,
components or steps. By use of the term "may" herein, it is
intended that any described attributes that "may" be included are
optional.
[0023] The disclosure of "a" or "one" to describe an element,
ingredient, component or step is not intended to foreclose
additional elements, ingredients, components or steps. Plural
elements, ingredients, components or steps can be provided by a
single integrated element, ingredient, component or step.
Alternatively, a single integrated element, ingredient, component
or step might be divided into separate plural elements,
ingredients, components or steps.
[0024] It is understood that the present description is intended to
be illustrative and not restrictive. Many embodiments as well as
many applications besides the examples provided will be apparent to
those of skill in the art upon understanding. the present
disclosure. The scope of the claimed invention should, therefore,
not be determined with limiting reference to the description, but
should instead be determined with reference to the appended claims,
along with the full scope of equivalents to which the claims are
entitled. Any disclosure of an article or reference, including
patent applications and publications, is incorporated by reference
herein for all purposes. Any omission in the following claims of
any aspect of subject matter disclosed herein is not a disclaimer
of such subject matter.
* * * * *