U.S. patent application number 12/877804 was filed with the patent office on 2010-12-30 for methods of retrofitting electric power steering systems for vehicles.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS, INC.. Invention is credited to RICHARD W. TOPPING.
Application Number | 20100326763 12/877804 |
Document ID | / |
Family ID | 41061791 |
Filed Date | 2010-12-30 |
United States Patent
Application |
20100326763 |
Kind Code |
A1 |
TOPPING; RICHARD W. |
December 30, 2010 |
METHODS OF RETROFITTING ELECTRIC POWER STEERING SYSTEMS FOR
VEHICLES
Abstract
A method for retrofitting an electric power steering system for
a vehicle, the electric power steering system comprising a torsion
bar and a controller configured to facilitate steering control
based at least in part on a deflection or a strain of the torsion
bar, is provided. The method includes the steps of obtaining the
electric power steering system, and reconfiguring the controller so
as to be further configured to at least facilitate adjusting a
stiffness of the torsion bar based at least in part on a parameter
pertaining to operation of the vehicle.
Inventors: |
TOPPING; RICHARD W.; (ANN
ARBOR, MI) |
Correspondence
Address: |
INGRASSIA FISHER & LORENZ, P.C. (GM)
7010 E. COCHISE ROAD
SCOTTSDALE
AZ
85253
US
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS,
INC.
DETROIT
MI
|
Family ID: |
41061791 |
Appl. No.: |
12/877804 |
Filed: |
September 8, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12045955 |
Mar 11, 2008 |
7810606 |
|
|
12877804 |
|
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Current U.S.
Class: |
180/446 |
Current CPC
Class: |
B62D 6/10 20130101; B62D
5/0475 20130101; B62D 5/0463 20130101 |
Class at
Publication: |
180/446 |
International
Class: |
B62D 5/04 20060101
B62D005/04 |
Claims
1. A method of retrofitting an electric power steering system for a
vehicle, the electric power steering system comprising a torsion
bar and a controller configured to facilitate steering control
based at least in part on a deflection or a strain of the torsion
bar, the method comprising the steps of: obtaining the electric
power steering system; and reconfiguring the controller so as to be
further configured to at least facilitate adjusting a stiffness of
the torsion bar based at least in part on a parameter pertaining to
operation of the vehicle.
2. The method of claim 1, further comprising the step of:
reconfiguring the controller so as to be further configured to
obtain the parameter.
3. The method of claim 1, wherein the parameter comprises a
velocity of the vehicle.
4. The method of claim 1, wherein the parameter comprises an
acceleration of the vehicle.
5. The method of claim 1, wherein the vehicle includes a steering
wheel, and the parameter comprises a displacement of the steering
wheel.
6. The method of claim 1, further comprising the step of:
reconfiguring the controller to incorporate the parameter into a
steering assist signal for steering control.
7. The method of claim 1, further comprising the step of:
reconfiguring the controller to incorporate a second parameter into
a steering assist signal for steering control.
8. The method of claim 1, further comprising the step of:
reconfiguring the controller so as to be further configured to
directly adjust the stiffness of the torsion bar using the
parameter.
9. The method of claim 1, further comprising the step of:
reconfiguring the controller so as to be further configured to
generate a torsion bar adjustment signal based at least in part on
the parameter.
10. The method of claim 9, further comprising the step of:
introducing a torsion bar adjuster coupled between the controller
and the torsion bar and configured to receive the torsion bar
adjustment signal and adjust the stiffness of the torsion bar in
accordance therewith.
11. The method of claim 10, wherein the step of introducing the
torsion bar adjuster further comprises the step of: introducing the
torsion bar adjuster as part of a steering column of the electric
power steering system.
12. A method of retrofitting an electric power steering system for
a vehicle, the electric power steering system comprising a torsion
bar, the method comprising the steps of: reconfiguring a controller
so as to be configured to generate a torsion bar adjustment signal
using a parameter pertaining to operation of the vehicle; and
introducing a torsion bar adjuster to be coupled between the
controller and the torsion bar and configured to receive the
torsion bar adjustment signal and adjust a stiffness of the torsion
bar in accordance therewith.
13. The method of claim 12, further comprising the step of:
reconfiguring the controller so as to be further configured to
obtain the parameter.
14. The method of claim 12, wherein the parameter comprises a
velocity of the vehicle.
15. The method of claim 12, wherein the parameter comprises an
acceleration of the vehicle.
16. The method of claim 12, wherein the vehicle includes a steering
wheel, and the parameter comprises a displacement of the steering
wheel.
17. A method of retrofitting an electric power steering system for
a vehicle, the electric power steering system comprising a torsion
bar and a controller, the method comprising the steps of:
reconfiguring the controller so as to be further configured to
obtain a parameter pertaining to operation of the vehicle; and
reconfiguring the controller so as to be further configured to at
least facilitate adjusting a stiffness of the torsion bar using the
parameter.
18. The method of claim 17, further comprising the step of:
reconfiguring the controller so as to be further configured to
directly adjust the stiffness of the torsion bar using the
parameter.
19. The method of claim 17, further comprising the step of:
reconfiguring the controller so as to be further configured to
generate a torsion bar adjustment signal based at least in part on
the parameter.
20. The method of claim 19, further comprising the step of:
introducing a torsion bar adjuster coupled between the controller
and the torsion bar and configured to receive the torsion bar
adjustment signal and adjust the stiffness of the torsion bar in
accordance therewith.
Description
PRIORITY CLAIM/CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation (division) of, and claims
priority from, U.S. application Ser. No. 12/045,955 filed Mar. 11,
2008, the entirety of which is incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention generally relates to vehicles, and
more particularly relates to electric power steering systems for
vehicles with adjustable torsion bars and methods for retrofitting
electric power steering systems for vehicles.
BACKGROUND
[0003] Vehicle electric power steering systems generally utilize an
electric motor to provide assist or active motion of the front road
wheels to reduce steering wheel effort for drivers of the vehicles.
Certain electric power steering systems, commonly referred to as
speed sensitive electric power steering systems, modulate the
amount of steering assist based on a speed of the vehicle. As the
speed of the vehicle increases, a speed sensitive electric power
steering system typically reduces the current of the electric motor
to thereby reduce the steering assist in response to the increased
vehicle speed. However, as steering loads increase, this may result
in reduced precision for the electric power steering system, for
example as a result of increased deflections of a torsion bar of
the electric power steering system.
[0004] Accordingly, it is desirable to provide an improved electric
power steering system, for example that provides increased
precision, such as when steering loads are increased. Furthermore,
other desirable features and characteristics of the present
invention will become apparent from the subsequent detailed
description of the invention and the appended claims, taken in
conjunction with the accompanying drawings and this background of
the invention.
SUMMARY
[0005] In accordance with an exemplary embodiment, a method of
retrofitting an electric power steering system for a vehicle, the
electric power steering system comprising a torsion bar and a
controller configured to facilitate steering control based at least
in part on a deflection or a strain of the torsion bar, is
provided. The method comprises the steps of obtaining the electric
power steering system, and reconfiguring the controller so as to be
further configured to at least facilitate adjusting a stiffness of
the torsion bar based at least in part on a parameter pertaining to
operation of the vehicle.
[0006] In accordance with another exemplary embodiment, a method of
retrofitting an electric power steering system for a vehicle, the
electric power steering system comprising a torsion bar, is
provided. The method comprises the steps of reconfiguring a
controller so as to be configured to generate a torsion bar
adjustment signal using a parameter pertaining to operation of the
vehicle, and introducing a torsion bar adjuster to be coupled
between the controller and the torsion bar and configured to
receive the torsion bar adjustment signal and adjust a stiffness of
the torsion bar in accordance therewith.
[0007] In accordance with a further exemplary embodiment, a method
of retrofitting an electric power steering system for a vehicle,
the electric power steering system comprising a torsion bar and a
controller, is provided. The method comprises the steps of
reconfiguring the controller so as to be further configured to
obtain a parameter pertaining to operation of the vehicle, and
reconfiguring the controller so as to be further configured to at
least facilitate adjusting a stiffness of the torsion bar using the
parameter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and:
[0009] FIG. 1 is a schematic drawing of an electric power steering
system for a vehicle that has a steering column, a torsion bar, a
detection unit, a controller, a torsion bar adjuster, and an
electric motor, accordance with an exemplary embodiment of the
present invention;
[0010] FIG. 2 is a schematic drawing of a portion of the electric
power steering system of FIG. 1, depicting the torsion bar, the
detection unit, and the torsion bar adjuster thereof, in accordance
with an exemplary embodiment of the present invention; and
[0011] FIG. 3 is a flowchart of a method for retrofitting an
electric power steering system of a vehicle to include an active
torsion bar, such as in the electric power steering system of FIG.
1, in accordance with an exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0012] The following detailed description of the invention is
merely exemplary in nature and is not intended to limit the
invention or the application and uses of the invention.
Furthermore, there is no intention to be bound by any theory
presented in the preceding background of the invention or the
following detailed description of the invention.
[0013] FIG. 1 is a schematic drawing of an electric power steering
system 100 for a vehicle having road wheels 101 and a steering
wheel 102, in accordance with an exemplary embodiment of the
present invention. The electric power steering system 100 includes
a steering column 104, a torsion bar 106, a controller 108, and an
electric motor 109. In the depicted embodiment, the electric power
steering system 100 also includes a pinion shaft 110, a control
pinion 111, an assist pinion 112, a rack 113, tie rods 114, a motor
shaft 115, a detection unit 116, and a torsion bar adjuster
118.
[0014] The steering column 104 is coupled to the steering wheel
102, and is rotationally movable thereby. The steering column 104
is configured to at least facilitate movement of the road wheels
101 based at least in part on movement of the steering wheel
102.
[0015] The torsion bar 106 is coupled to the steering column 104,
and is configured to receive a torque therefrom during rotational
movement of the steering column 104. In conjunction with the
torsion bar adjuster 118 and controller 108, the torsion bar 106 is
an active torsion bar whose stiffness is adjustable by means of the
controller 108, for example based on vehicle speed, vehicle
acceleration, steering wheel displacement, steering load, and/or
other parameters or conditions. As depicted in FIG. 1, the torsion
bar 106, the detection unit 116, and the torsion bar adjuster 118
are housed together in a common housing 105. However, this may vary
in other embodiments.
[0016] The pinion shaft 110 is coupled between the torsion bar 106
and the plurality of road wheels 101, and is configured to
rotationally move based at least in part on the torque.
Specifically, in the depicted embodiment, the pinion shaft 110 is
coupled between the torsion bar 106 and the control pinion 111. The
pinion shaft 110 is configured to rotationally move based at least
in part on the above-referenced torque, and to thereby ultimately
influence the position of the road wheels 101 via the control
pinion 111, the rack 113, and the tie rods 114. Specifically, in a
preferred embodiment, the pinion shaft 110 receives torque from the
torsion bar 106 resulting from the above-referenced torque provided
to the torsion bar 106 via the steering column 104, and
rotationally moves in response thereto. The rotational movement of
the pinion shaft 110 in turn manipulates the control pinion 111,
which in turn causes movement of the rack 113 coupled thereto,
which in turn causes movement of the tie rods 114 coupled thereto,
and which ultimately influences the position of the road wheels 101
coupled thereto.
[0017] The rack 113 is coupled between the pinion shaft 110 and the
plurality of road wheels 101, and is configured to move, and
thereby at least facilitate changing a position of the plurality of
road wheels 101, based at least in part on rotational movement of
the pinion shaft 110. The control pinion 111 is coupled between the
pinion shaft 110 and the rack 113, and is configured to at least
facilitate movement of the rack 113 based at least in part on
movement of the pinion shaft 110. The tie rods 114 are coupled
between the rack 113 and the road wheels 101, and are configured to
at least facilitate movement of the road wheels 101 based at least
in part on movement of the rack 113.
[0018] The controller 108 is coupled to the electric motor 109, and
is also coupled directly or indirectly to the torsion bar 106. The
controller 108 is configured to at least facilitate adjusting the
torsion bar 106 based at least in part on a parameter pertaining to
operation of the vehicle. In an exemplary embodiment, the
controller 108 adjusts the stiffness of the torsion bar 106. The
controller 108 is further configured to generate a steering assist
signal 120 based at least in part on a deflection or strain of the
torsion bar 106 or a torque carried by the torsion bar 106, and to
transmit the steering assist signal 120 to the electric motor
109.
[0019] In a preferred embodiment, the controller 108 is further
coupled to the detection unit 116 and to the torsion bar adjuster
118. The controller 108 is configured to receive a deflection,
strain, or torque signal 122 from the detection unit 116. The
controller 108 is further configured to generate the steering
assist signal 120 based at least in part on the deflection, strain,
or torque signal 122. For example, when an increase in steering
load for the electric power steering system 100 occurs, the
controller 108 provides instructions to adjust the steering assist
signal 120 to reduce steering effort and improve steering precision
and the driving experience for a driver of the vehicle, in a
preferred embodiment of the present invention.
[0020] Also in a preferred embodiment, the controller 108 generates
the steering assist signal 120 based not only on the deflection,
strain, or torque signal 122, but also based on one or more
additional parameters pertaining to operation of the vehicle. For
example, in one such embodiment, the controller 108 generates the
steering assist signal 120 based upon the deflection, strain, or
torque signal 122 and also based upon values of a vehicle speed, a
vehicle acceleration, and/or a displacement of the steering wheel
102, which the controller 108 may receive from one or more
non-depicted sensors and/or other sources. This allows for further
improved steering effort and precision, for example as vehicle
speed, vehicle acceleration, and/or steering wheel displacement
increases and/or steering loads increase.
[0021] The controller 108 may receive such values of vehicle speed,
vehicle acceleration, and/or steering wheel 102 displacement as one
or more signals from one or more non-depicted signals,
transmitters, and/or other sources in one preferred embodiment.
However, this may vary in other embodiments. Also, as referenced
herein, vehicle speed and vehicle acceleration can refer to any
number of different types of speed and acceleration measured on or
with respect to and/or otherwise used in connection with the
vehicle. Additionally, other parameters may also be used, among
other possible variations in different embodiments of the present
invention.
[0022] The controller 108 transmits the steering assist signal 120
to the electric motor 109 for implementation. In the depicted
embodiment, the steering assist signal 120 includes instructions
for the electric motor 109 as to a desired electric current to
reduce steering effort for the driver of the vehicle, for example
that results in a desired manipulation of the assist pinion 112, in
order to ultimately influence steering effort at the steering wheel
102 and positioning of the road wheels 101 in a desired manner.
Similarly, the steering assist signal 120 may include instructions
as to a desired electric current that results, directly or
indirectly, in a desired manipulation of the control pinion 111,
and/or one or more other types of instructions to ultimately
influence positioning of the road wheels 101 in a desired
manner.
[0023] Also in a preferred embodiment, the controller 108 at least
facilitates the adjustment of the stiffness of the torsion bar 106
via a torsion bar adjustment signal 124 that is transmitted to the
torsion bar adjuster depicted in FIG. 2 and described below in
connection therewith, that adjusts the stiffness of the torsion bar
106 based on the torsion bar adjustment signal 124. In such an
embodiment, the torsion bar adjustment signal 124 includes
instructions as to a desired adjustment for the torsion bar 106.
The torsion bar adjustment signal 124 may also be transmitted to
another, non-depicted unit or device which performs the same
function. In the depicted embodiment, the deflection, strain, or
torque signal 122 travels from the detection unit 116 in the
direction of the arrow representing the deflection, strain, or
torque signal 122 in FIG. 1 toward the controller 108.
[0024] In a preferred embodiment, the controller 108 generates the
torsion bar adjustment signal 124 based on one or more parameters
pertaining to operation of the vehicle. For example, in one such
embodiment the controller 108 generates the torsion bar adjustment
signal 124 based upon values of vehicle speed, vehicle
acceleration, and/or steering wheel 102 displacement which, as
referenced above, the controller 108 may receive from one or more
non-depicted sensors and/or other sources. Other parameters may
also be used. The controller 108 transmits the torsion bar
adjustment signal 124 to the torsion bar adjuster 118. It will be
appreciated that the parameters used in connection with the
steering assist signal 120 may differ from those used in connection
with the torsion bar adjustment signal 124.
[0025] The electric motor 109 is coupled to the controller 108, and
is configured to receive the steering assist signal 120 therefrom
and to at least facilitate implementation of the steering assist
signal 120. In one preferred embodiment depicted in FIG. 1, the
electric motor 109 is coupled to the rack 113. For example, the
electric motor 109 may be coupled to the rack 113 via the assist
pinion 112 via the above-referenced motor shaft 115, and may
implement the steering assist signal 120 thereby. Specifically, the
electric motor 109 produces an electric current resulting from an
external voltage source, such as a battery, not depicted. The
current causes rotational movement of the motor shaft 115 that
results in a manipulation of the assist pinion 112 in a desired
manner. The current is based on instructions received via the
steering assist signal 120. The manipulation of the assist pinion
112 in turn causes reduction in steering effort required of the
driver in a desired manner. The electric motor 109 may also be
otherwise coupled to the rack 113 via one or more other techniques
to cause reduction in steering effort required of the driver in a
desired manner.
[0026] In a preferred embodiment, the amount of electric current of
the electric motor 109 varies based on the instructions provided in
the steering assist signal 120, which in turn is dependent upon the
desired amount of steering assist as determined by the controller
108. The amount of electric current of the electric motor 109 in
turn affects the amount of torque carried by the motor shaft 115
and, accordingly, affects the amount of steering assist provided in
accordance with the steering assist signal 120 instructions.
[0027] In an alternate preferred embodiment, the electric motor 109
is coupled, either directly or indirectly, to the steering column
104. In this embodiment, the torsion bar 106, torsion bar adjuster
118, and detection unit 116 are repositioned between the electric
motor 109 and the steering wheel 102. As in the embodiment shown in
FIG. 1, the torque from the electric motor 109 provides steering
assist in accordance with the steering assist signal 120
instructions. But, in this embodiment, the assist torque is applied
to the steering column 104 rather than the rack 113.
[0028] The detection unit 116 is coupled between the torsion bar
106 and the controller 108. The detection unit 116 is configured to
detect deflection or strain of the torsion bar 106 or torque
carried by the torsion bar 106, to generate the above-referenced
deflection, strain, or torque signal 122 pertaining thereto, and
transmit the deflection, strain, or torque signal 122 to the
controller 108. The detection unit 116 may be housed with the
torsion bar, as depicted in FIG. 2, in certain embodiments.
However, in other embodiments this may vary. As will be described
below in connection with FIG. 2, in certain preferred embodiments
the detection unit 116 may include one or more of the following: a
displacement transducer, a strain transducer, and/or a torque
transducer. A more detailed drawing of an exemplary embodiment of
the detection unit 116 is provided in FIG. 2 and will be described
below in connection therewith.
[0029] The torsion bar adjuster 118 is coupled between the
controller 108 and the torsion bar 106. The torsion bar adjuster
118 is configured to adjust the stiffness of the torsion bar 106 in
accordance with the torsion bar adjustment signal 124. In one
preferred embodiment, the torsion bar adjustment unit 188 comprises
two or more non-depicted disks at each end of the torsion bar 106
that adjust stiffness in the torsion bar 106 through torque between
them caused by an electric current. However, this may vary in other
embodiments. For example, in various other embodiments, the torsion
bar adjustment unit 188 may comprise one or more electromagnetic,
electromechanical, hydromechanical, and/or other types of devices
that serves as a stiffening mechanism that works across the length
of the torsion bar 106. Also, in certain embodiments the torsion
bar adjustment unit 118 and/or the detection unit 116 may be part
of the same unit, and/or may be part of the controller 108.
[0030] It will be appreciated that in certain embodiments, one or
more of the depicted components of the electric power steering
system 100 may not be necessary. For example, in the alternate
embodiments described directly above, the assist pinion 112 is
unnecessary because the electric motor 109 provides the desired
steering assist instead via the steering column 104 and the control
pinion 111. It will similarly be appreciated that while the
electric power steering system 100 is shown as implemented in
connection with a rack and pinion steering system, in other
embodiments the electric power steering system 100 may instead by
implemented in connection with a recirculating ball steering system
and/or another type of system.
[0031] FIG. 2 is a schematic drawing of a portion of the electric
power steering system 100 of FIG. 1, depicting the steering column
104 and the torsion bar 106 along with the pinion shaft 110, the
detection unit 116, and the torsion bar adjuster 118, in accordance
with an exemplary embodiment of the present invention. In the
depicted embodiment, the detection unit 116 comprises a transducer
206. The transducer 206 is configured to generate the
above-referenced deflection, strain, or torque signal 122 based on
the relative motion detected by the transducer 206. However, this
may vary in other embodiments.
[0032] In one preferred embodiment, the transducer 206 comprises a
strain transducer configured to detect a strain in the torsion bar
106. In another preferred embodiment, the transducer 206 comprises
a displacement transducer configured to detect the torsional
deflection of the torsion bar 106. In another preferred embodiment,
the transducer 206 comprises a torque transducer configured to
detect torque carried by the torsion bar 106. In yet other
embodiments, multiple transducers 206 of either the same type or
different types may be used. As described in greater detail above,
the deflection, strain, or torque signal 122 influences the
steering assist of the vehicle, for example by influencing the
steering assist signal 120 described above in connection with FIG.
1.
[0033] The torsion bar adjuster 118 is coupled between the
controller 108 of FIG. 1 (not depicted in FIG. 2) and the torsion
bar 106. The torsion bar adjuster 118 is configured to receive the
torsion bar adjustment signal 124 and to adjust the stiffness of
the torsion bar 106 in accordance therewith. As mentioned above, in
one preferred embodiment, the torsion bar adjustment unit 188
comprises two or more non-depicted disks at each end of the torsion
bar 106 that adjust stiffness in the torsion bar 106 through torque
between them caused by an electric current. However, this may vary
in other embodiments. For example, in various other embodiments,
the torsion bar adjustment unit 188 may comprise one or more
electromagnetic, electromechanical, hydromechanical, and/or other
types of devices. In yet other embodiments, the torsion bar
adjuster 118 may be part of the controller 108 of FIG. 1.
[0034] FIG. 3 is a flowchart of a process 300 for retrofitting an
electric power steering system of a vehicle to include an active
torsion bar, such as in the electric power steering system 100 of
FIG. 1, in accordance with an exemplary embodiment of the present
invention. As depicted in FIG. 3, the process 300 begins with the
step of obtaining an electric power steering system for a vehicle
(step 302). The electric power steering system obtained in step 302
is preferably a typical electric power steering system having a
non-adjustable torsion bar, a controller configured to detect
deflection or strain of the torsion bar or a torque carried by the
torsion bar and to generate a steering assist signal based at least
in part on the deflection or strain of the torsion bar or a torque
carried by the torsion bar, and an electric motor coupled to the
controller and configured to receive the steering assist signal
therefrom and to at least facilitate implementing the steering
assist signal.
[0035] In addition, in one preferred embodiment, the controller is
further reconfigured to receive a value of one or more parameters
pertaining to one or more vehicle states (step 304). For example,
in one preferred embodiment, the parameters include a velocity, an
acceleration of the vehicle, and/or a displacement of the steering
wheel of the vehicle. Other parameters may also be used. Step 304
may not be necessary in certain embodiments, for example in which
the controller is already configured to receive values of the
desired parameters.
[0036] The controller of the electric power steering system
obtained in step 302 is reconfigured to at least facilitate
adjustment of the stiffness of the torsion bar based at least in
part on the value of the one or more parameters (step 306). In a
preferred embodiment, the controller is reconfigured in step 306 to
generate a torsion bar adjustment signal based on the value of the
one or more parameters obtained in step 304. In other embodiments,
the controller may be reconfigured in step 306 to directly adjust
the stiffness of the torsion bar, based at least in part on the
value of the one or more parameters obtained in step 304.
[0037] Also in a preferred embodiment, the controller is also
reconfigured to incorporate values of one or more parameters into
the steering assist signal (step 308). For example, in one such
preferred embodiment, the controller may be reconfigured to
generate the steering assist signal based not only the torsion bar
deflection, strain, or torque, but also on values of vehicle speed,
vehicle acceleration, steering wheel displacement, and/or one or
more other parameters. It will be appreciated that the parameters
used in connection with the steering assist signal may differ from
those used in connection with the torsion bar adjustment signal. It
will also be appreciated that in certain embodiments step 308 may
not be necessary, for example in which the steering assist signal
is determined solely based on the torsion bar deflection, strain,
or torque or in which the controller is already configured to
receive values of the desired parameters.
[0038] In addition, a torsion bar adjuster is introduced to the
electric power steering system (step 310). The torsion bar adjuster
is coupled between the controller and the torsion bar, and is
configured to receive the torsion bar adjustment signal from the
controller and adjust the torsion bar in accordance therewith. In
one preferred embodiment, the torsion bar adjuster may be
integrated as part of a steering column of the electric power
steering system, such as that depicted in FIG. 2 and described
above in connection therewith. However, this may vary in other
embodiments. For example, in certain alternate embodiments, the
torsion bar adjuster is introduced as part of the controller, or an
existing component of the electric power steering system can be
reconfigured to perform the functions of the torsion bar
adjuster.
[0039] It will be appreciated that certain steps of the process 300
depicted in FIG. 3 may not be necessary in certain embodiments,
and/or that certain steps of the process 300 may be combined into a
single step. It will similarly be appreciated that certain steps of
the process 300 may be performed simultaneously or in a different
order than that depicted in FIG. 3 and/or described above in
connection therewith.
[0040] Accordingly, an improved electric power steering system is
provided with an active torsion bar and improved steering assist
functionality. The improved electric power steering system allows
for improved precision and/or an improved driving experience for
the vehicle. In addition, a method is provided for retrofitting an
electric power steering system to include an active torsion bar,
and to thereby allow for improved precision and/or an improved
driving experience for the vehicle.
[0041] While at least one exemplary embodiment has been presented
in the foregoing detailed description, it should be appreciated
that a vast number of variations exist. It should also be
appreciated that the exemplary embodiment or exemplary embodiments
are only examples, and are not intended to limit the scope,
applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing the
exemplary embodiment or exemplary embodiments. It should be
understood that various changes can be made in the function and
arrangement of elements without departing from the scope of the
invention as set forth in the appended claims and the legal
equivalents thereof.
* * * * *