U.S. patent application number 15/872451 was filed with the patent office on 2018-05-24 for valve switching controls for adjustable damper.
The applicant listed for this patent is Tenneco Automotive Operating Company Inc.. Invention is credited to David R. BLANKENSHIP, Scott S. DUNAWAY, Jeffrey T. GARDNER, Karl C. KAZMIRSKI, Jeroen K. PAENHUYSEN.
Application Number | 20180141401 15/872451 |
Document ID | / |
Family ID | 56368672 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180141401 |
Kind Code |
A1 |
DUNAWAY; Scott S. ; et
al. |
May 24, 2018 |
VALVE SWITCHING CONTROLS FOR ADJUSTABLE DAMPER
Abstract
A damper system and method for a vehicle includes a shock
absorber and a damper module. The shock absorber includes a
plurality of digital valves. The shock absorber is operable at one
of multiple damping states based on a valve state of the digital
valves. The damper module is coupled to each of the digital valves
and controls each of the digital valves to a desired state based on
a damper setting. The damper module determines a target damping
state, where the target state is one of the multiple damping
states. The damper module performs a switch operation to control
the valve state of the plurality of digital valves to a given
desired state when the target damping state is different from a
present damping state.
Inventors: |
DUNAWAY; Scott S.;
(Carleton, MI) ; BLANKENSHIP; David R.; (Canton,
MI) ; KAZMIRSKI; Karl C.; (Temperance, MI) ;
PAENHUYSEN; Jeroen K.; (Ann Arbor, MI) ; GARDNER;
Jeffrey T.; (Woodland Park, CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Tenneco Automotive Operating Company Inc. |
Lake Forest |
IL |
US |
|
|
Family ID: |
56368672 |
Appl. No.: |
15/872451 |
Filed: |
January 16, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14947222 |
Nov 20, 2015 |
9925842 |
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15872451 |
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14191885 |
Feb 27, 2014 |
9217483 |
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14947222 |
|
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61770426 |
Feb 28, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60G 2500/114 20130101;
B60G 2204/112 20130101; F16F 9/464 20130101; F16F 9/3207 20130101;
B60G 17/08 20130101; F16F 9/463 20130101; F16F 9/3292 20130101;
B60G 13/00 20130101; B60G 2500/10 20130101; B60G 2401/17 20130101;
B60G 17/015 20130101; B60G 2600/182 20130101; B60G 2202/24
20130101; B60G 2600/71 20130101; B60G 17/018 20130101; B60G
17/01908 20130101; B60G 17/0152 20130101; B60G 2800/162
20130101 |
International
Class: |
B60G 17/08 20060101
B60G017/08; F16F 9/46 20060101 F16F009/46; B60G 13/00 20060101
B60G013/00; F16F 9/32 20060101 F16F009/32; B60G 17/015 20060101
B60G017/015; B60G 17/019 20060101 B60G017/019 |
Claims
1. A method for damping motion of a body of a vehicle during travel
of the vehicle, wherein at least one shock absorber is coupled
between a sprung portion and an unsprung portion of the vehicle,
and wherein the shock absorber has a plurality of independently
controllable digital valves, each said digital valve being movable
between a first position providing a first flow area for a flow of
fluid therethrough, and a second position providing a second flow
area different than the first flow area for a flow of fluid
therethrough, the method comprising: generating a target damping
state for the shock absorber; transmitting the target damping state
to a damper module associated with the shock absorber; and using
the damper module to compare the target damping state to a present
damping state of the shock absorber, and to generate a control
operation that selectively controls one or more selected valves of
the plurality of digital valves to achieve the target damping
state.
2. The method of claim 1, wherein the damper module actuates
selected ones of the plurality of digital valves in a predetermined
order to achieve the target damping state.
3. The method of claim 1, wherein the damper module selects one of
a predetermined plurality of available damping states, and controls
switching of the plurality of digital valves in accordance with the
selected one of the plurality of available damping states, to
achieve the target damping state.
4. The method of claim 1, wherein at least one of the plurality of
digital valves is predesignated as a primary valve and at least one
of the plurality of digital valves is predesignated as a secondary
valve, and wherein the primary valve includes a greater flow area
than the secondary valve.
5. The method of claim 1, further comprising using the damper
module to implement a time delay after switching a first one of the
plurality of digital valves before initiating switching of a second
one of the plurality of digital valves.
6. The method of claim 1, further comprising using signals from at
least one of: an angular rate sensor, an inertial measurement unit
(IMU), a temperature sensor, a height sensor, a pressure sensor,
and an accelerometer, to form the target damping signal.
7. The method of claim 1, further comprising causing the damper
module to implement a valve staggering control scheme by which a
transient state of each one of the plurality of digital valves is
controlled by incorporating time delays between actuation
operations for certain ones of the plurality of digital valves.
8. The method of claim 7, wherein the valve staggering control
scheme includes a flow-area staggering scheme, in which a size of a
flow area of each one of the plurality of digital valves is
considered and used by the damper module in determining a specific
sequence for actuating specific ones of the plurality of digital
valves to achieve the target damping state.
9. The method of claim 1, further comprising causing the damper
module to implement a state transition control scheme for
controlling actuation of the plurality of digital valves, the state
transition control scheme including at least one of: a fixed-step
control in which damping state transitions from the present damping
state to the target damping state are implemented in a fixed number
of steps; or a fixed transition time control in which needed
damping state transitions implemented by the damper module
switching of the plurality of digital valves, to change from the
present damping state to the target damping state, are implemented
by the damper module in a preset amount of time.
10. A method for damping motion of a body of a vehicle during
travel of the vehicle, wherein at least one shock absorber is
coupled between a sprung portion and an unsprung portion of the
vehicle, and wherein the shock absorber has a plurality of
independently controllable digital valves, each said digital valve
being movable between a first position providing a first flow area
for a flow of fluid therethrough, and a second position providing a
second flow area different than the first flow area for a flow of
fluid therethrough, the method comprising: receiving signals from
at least one sensor associated with the vehicle; using the signals
to generate a target damping state for the shock absorber;
transmitting the target damping state to a damper module associated
with the shock absorber; using the damper module to compare the
target damping state to a present damping state of the shock
absorber; using the damper module to determine a control operation
for controlling at least one of the plurality of digital valves to
implement the target damping state; and using the damper module to
control the at least one of the plurality of digital valves in
accordance with the control operation, to thus cause a select one
of a plurality of available damping states to be implemented using
the plurality of digital valves, and wherein the select one of the
available damping states at least substantially matches the target
damping state.
11. The method of claim 10, further comprising: predefining each
one of the plurality of digital valves as either a primary valve or
as a secondary valve; using the damper module to select a specific
one of the secondary valves; using the damper module to select a
specific one of the primary valves; and switching the secondary
valve from the first position to the second position after the
primary valve is switched from the first position to the second
position and after a preset time period has lapsed after said
primary valve has been switched.
12. The method of claim 10, further comprising: using the damper
module to determine whether at least one of the plurality of
digital valves is to be switched from the first position to the
second position based on the present damping state and the target
damping state; when one select digital valve from among the
plurality of digital valves is to be switched, using the damper
module to switch the one select digital valve from the first
position to the second position, and when more than one digital
valve from among the plurality of digital valves is to be switched,
using the damper module to switch a primary valve from among the
more than one digital valves from the first position to the second
position, and switching a non-primary valve from the more than one
digital valves from the first position to the second position after
the primary valve, and after a preset time period has lapsed; and
configuring the primary valve with a flow area larger than the
non-primary valve.
13. The method of claim 10, further comprising defining each one of
the plurality of digital valves as a primary valve or a secondary
valve, and further such that at least one of the plurality of
digital valves is a primary valve and at least one of the plurality
of digital valves is a secondary valve; and providing the at least
one of the plurality of digital valves that forms a primary valve
with a larger flow area than a flow area of the at least one of the
plurality of digital valves that forms a secondary valve.
14. The method of claim 13, wherein the control operation comprises
using the damper module to determine which one or more of the
plurality of digital valves are to be switched from the first
position to the second position based on the present damping state
and the target damping state; and when more than one digital valve
of the plurality of digital valves is to be switched from the first
position to the second position, using the damper module to perform
a plurality of switching actions to switch selected ones of the
plurality of digital valves, one at a time, with a preset time
period disposed between each said switching action; and when the
selected ones of the plurality of digital valves being switched
include the primary valve, causing the damper module to switch the
primary valve before the secondary valve.
15. The method of claim 10, wherein the control operation includes
implementing at least one of: a staggering control for generating a
time delay between a primary valve and a secondary valve of the
plurality of digital valves, such that the primary valve is
switched from the first position to the second position before the
secondary valve; a state transition control to switch one or more
of the plurality of digital valves such that the shock absorber
operates at a transient damping state prior to operating at the
target damping state, the transient damping state being one of the
plurality of available damping states different from the target
damping state and the present damping state, and wherein the
primary valve and the secondary valve are among the plurality of
digital valves; or a state transition control for switching one or
more of the plurality of digital valves, which is based on
proportional-integral-derivative (PID) control algorithms which
determine a number of transient states to use between the present
damping state and the target damping state.
16. The method of claim 10, wherein the target damping state is
generated using a master module disposed in the vehicle remotely
from the damper module, and wherein the master module receives and
uses the signals from the sensor.
17. The method of claim 10, wherein the control operation comprises
using a quadratic control scheme to control switching of selected
ones of the plurality of digital valves when the present damping
state is different from the target damping state.
18. The method of claim 10, further comprising at least one of:
using the damper module to periodically apply an actuation current
pulse to a select one of the plurality of digital valves that is
already in the second position; or using the damper module to apply
an actuation current pulse to a specific one of the digital valves
which is in the second position when a sensed temperature of the
shock absorber is below a preset threshold.
19. The method of claim 10, wherein the plurality of available
damping states is determined by a number "N" of the plurality of
digital valves, and wherein N is an integer, and wherein the shock
absorber has 2.sup.N number of damping states comprising the
available damping states.
20. The method of claim 10, further comprising using the damper
module to: apply a hold current pulse to maintain a specific one of
the plurality of digital valves in the second position; and to
deactivate the hold current pulse to switch the specific one of the
plurality of digital valves from the second position to the first
position.
21. The method of claim 10, wherein the control operation includes
at least one of: applying a reverse current pulse to switch a
selected one of the plurality of digital valves from the second
position to the first position; or applying an actuation current
pulse to a selected one of the plurality of digital valves that is
in the second position when an acceleration of the shock absorber
is greater than or equal to a preset threshold.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/947,222, filed on Nov. 20, 2015, which
application is a divisional of U.S. patent application Ser. No.
14/191,885 filed on Feb. 27, 2014; which claims the benefit of U.S.
Provisional Application No. 61/770,426, filed on Feb. 28, 2013. The
entire disclosures of each of the above applications are
incorporated herein by reference.
FIELD
[0002] The present disclosure relates to an electrically adjustable
damper having one or more digital valves, and more particularly to
a valve switching control system and method for adjusting a damping
state of the electrically adjustable damper.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] Shock absorbers are used in conjunction with automotive
suspension systems to absorb unwanted vibrations which occur during
driving. To absorb the unwanted vibrations, shock absorbers are
generally connected between the sprung portion (body) and the
unsprung portion (suspension) of the automobile.
[0005] In recent years, vehicles may be equipped with an
electrically adjustable damping system that includes an adjustable
shock absorber having a digital valve. More particularly, the
adjustable shock absorber may include an electromechanical coil or
solenoid disposed therein.
[0006] A master module which may be located on the vehicle body can
be used to control a damping state of each of the adjustable shock
absorber. For example, the master module may receive data from
various sensors disposed along the sprung and unsprung portions of
the vehicle. Based on the data received, the master module
determines the damping state of the adjustable shock absorber and
actuates the electromechanical coil/solenoid disposed within the
shock absorber.
SUMMARY
[0007] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0008] The present disclosure provided for a damper system for a
vehicle. The damper system includes a shock absorber and a damper
module. The shock absorber includes a plurality of digital valves,
where each digital valve has a valve state. The shock absorber is
operable at one of multiple damping states based on the valve state
of the plurality of digital valves;
[0009] The damper module is coupled to each of the digital valves
and controls each of the digital valves to a desired state based on
a damper setting received from a master module. The damper module
determines a target damping state of the shock absorber based on
the damper setting. The target damping state is one of the multiple
damping states. The damper module performs a switch operation to
control the valve state of the plurality of digital valves to a
given desired state when the target damping state is different from
a present damping state.
[0010] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0011] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0012] FIG. 1 is an illustration of a vehicle having an adjustable
shock absorber;
[0013] FIG. 2 is a partial cross-sectional view of the shock
absorber;
[0014] FIG. 3 is an enlarged partial cross-sectional view of a
digital valve assembly disposed in the shock absorber;
[0015] FIG. 4 is a an example functional block diagram of a vehicle
damper system;
[0016] FIG. 5 is an example functional block diagram of a damper
module;
[0017] FIG. 6 illustrates a correlation between a damping state and
a valve state for each digital valve assembly of a shock absorber
having four digital valve assemblies;
[0018] FIG. 7 illustrates an actuation pulse, a hold current, and
an off-current;
[0019] FIG. 8 illustrates a staggering control of three actuation
pulses;
[0020] FIG. 9 is a graph of an example operation of a basic delay
staggering for a valve staggering control;
[0021] FIG. 10 is a graph of an example operation of a smart delay
staggering for the valve staggering control;
[0022] FIG. 11 is a graph of an example operation of a flow-area
staggering for the valve staggering control;
[0023] FIG. 12 is a graph of an example operation of a fixed-step
control for a state transition control;
[0024] FIG. 13 is a graph of an example operation of a fixed-time
control for the state transition control;
[0025] FIG. 14 is a graph of an example operation of an overdrive
control, a PID control, and quadratic control for the state
transition control;
[0026] FIG. 15 is a graph of an example operation of an
asymmetrical control for the state transition control;
[0027] FIG. 16 is a graph of pulse mode operation control for the
state transition control; and
[0028] FIG. 17 is a flow chart of an example method for performing
a valve switching operation.
[0029] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0030] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0031] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses. With reference to FIG. 1, an example of a vehicle 10
incorporating a suspension system having shock absorbers, each of
which incorporate a digital valve is now presented. The vehicle 10
includes a rear suspension 12, a front suspension 14 and a body 16.
The rear suspension 12 has a transversely extending rear axle
assembly (not shown) adapted to operatively support a pair of rear
wheels 18. The rear axle is attached to the body 16 by means of a
pair of shock absorbers 20 and by a pair of springs 22.
[0032] Similarly, the front suspension 14 includes a transversely
extending front axle assembly (not shown) to operatively support a
pair of front wheels 24. The front axle assembly is attached to the
body 16 by means of a pair of shock absorbers 20 and a pair of
springs 26.
[0033] The shock absorbers 20 serve to dampen the relative motion
of the unsprung portion (i.e., front and rear suspensions 12, 14)
with respect to the sprung portion (i.e., body 16) of vehicle 10.
While the vehicle 10 has been depicted as a passenger car having
front and rear axle assemblies, the shock absorbers 20 may be used
with other types of vehicles or in other types of applications
including, but not limited to, vehicles incorporating
non-independent front and/or non-independent rear suspensions,
vehicles incorporating independent front and/or independent rear
suspensions, or other suspension systems known in the art. Further,
the term "shock absorber" as used herein is meant to refer to
dampers in general and thus will include McPherson struts and other
damper designs known in the art.
[0034] Referring now to FIG. 2, an example of the shock absorber 20
is shown in greater detail. The shock absorber 20 comprises a
pressure tube 30, a piston assembly 32, a piston rod 34, a reserve
tube 36, and a base valve assembly 38. The pressure tube 30 defines
a working chamber 42. The piston assembly 32 is slidably disposed
within the pressure tube 30 and divides the working chamber 42 into
an upper working chamber 44 and a lower working chamber 46.
[0035] The piston rod 34 is attached to the piston assembly 32 and
extends through the upper working chamber 44 and through a rod
guide assembly 50 which closes the upper end of the pressure tube
30. The end of the piston rod 34 opposite to the piston assembly 32
is adapted to be secured to the sprung mass of the vehicle 10 in
the non-inverted configuration.
[0036] Valving within the piston assembly 32 controls the movement
of fluid between the upper working chamber 44 and the lower working
chamber 46 during movement of the piston assembly 32 within the
pressure tube 30. Since the piston rod 34 extends only through the
upper working chamber 44 and not the lower working chamber 46,
movement of the piston assembly 32 with respect to the pressure
tube 30 causes a difference in the amount of fluid displaced in the
upper working chamber 44 and the amount of fluid displaced in the
lower working chamber 46. The difference in the amount of fluid
displaced is known as the "rod volume" and it flows through the
base valve assembly 38.
[0037] The reserve tube 36 surrounds the pressure tube 30 to define
a fluid reservoir chamber 52 located between tubes 30 and 36. The
bottom end of the reserve tube 36 is closed by a base cup 54 which
is adapted to be connected to the unsprung mass of vehicle 10 in
the non-inverted configuration. The upper end of reserve tube 36 is
attached to rod guide assembly 50. The base valve assembly 38 is
disposed between the lower working chamber 46 and the reservoir
chamber 52 to control the flow of fluid between chambers 46 and 52.
When the shock absorber 20 extends in length, an additional volume
of fluid is needed in the lower working chamber 46 due to the "rod
volume" concept. Thus, fluid will flow from the reservoir chamber
52 to the lower working chamber 46 through the base valve assembly
38. When shock absorber 20 compresses in length, an excess of fluid
must be removed from the lower working chamber 46 due to the "rod
volume" concept, and therefore, fluid will flow from the lower
working chamber 46 to the reservoir chamber 52 through the base
valve assembly 38.
[0038] Alternatively, the shock absorber may be configured as an
inverted shock absorber. As the inverted shock absorber, the end of
the piston rod 34 opposite to the piston assembly 32 is adapted to
be secured to the unsprung mass of the vehicle 10 and the base cup
54 is adapted to be connected to the sprung mass of vehicle 10.
[0039] With reference to FIG. 3, the shock absorber 20 includes a
digital valve assembly 60. For brevity, the digital valve assembly
60 may be referred to as the digital valve 60. The digital valve 60
is a two position valve assembly which has a different flow area in
each of the two positions. The digital valve 60 may include a valve
housing 62, a sleeve 64, a spool 68, and a coil assembly 70.
[0040] The valve housing 62 defines a valve inlet 72 which is in
communication with the upper working chamber 44 through a fluid
passage (not shown) and a valve outlet 74 which is in fluid
communication with the reservoir chamber 52. The sleeve 64 is
disposed within the valve housing 62. The sleeve 64 defines an
annular inlet chamber 76 which is in communication with the valve
inlet 72 and a pair of annular outlet chambers 78 and 80 which are
in communication with valve outlet 74.
[0041] The spool 68 is slidingly received within the sleeve 64 and
axially travels within the sleeve 64 between the coil assembly 70
and a stop puck 82 disposed within the sleeve 64. A spring may be
used to bias the spool 68 away from the coil assembly 70 and
towards the stop puck 82. A shim 84 is disposed between the coil
assembly 70 and the sleeve 64 to control the amount of axial motion
for the spool 68.
[0042] The spool 68 defines a first flange 86 which controls fluid
flow between the annular inlet chamber 76 and the annular outlet
chamber 78 and a second flange 88 that controls fluid flow between
the annular inlet chamber 76 and the annular outlet chamber 80. The
flanges 86 and 88 thus control fluid flow from the upper working
chamber 44 to the reservoir chamber 52.
[0043] The coil assembly 70 is disposed within the sleeve 64 to
control the axial movement of the spool 68. The wiring connections
for the coil assembly 70 can extend through a rod guide housing
(not shown), through the sleeve 64, through valve housing 62 and/or
through the reserve tube 36. When there is no power provided to the
coil assembly 70, the damping characteristics will be defined by
the flow area of the digital valve 60 in its first position, the
piston assembly 32 and the base valve assembly 38.
[0044] The movement of spool 68 is controlled by supplying power to
coil assembly 70 to move the digital valve 60 to its second
position. The digital valve 60 can be kept in its second position
by continuing to supply power to the coil assembly 70 or by
providing means for retaining digital valve 60 in its second
position and discontinuing the supply of power to the coil assembly
70. The means for retaining the digital valve 60 in its second
position can include mechanical means, magnetic means or other
means known in the art. Once in its second position, movement to
the first position can be accomplished by terminating power to the
coil assembly 70 or by reversing the electrical current or
reversing the polarity of the power supplied to the coil assembly
70 to overcome the retaining means.
[0045] The shock absorber 20 may include one or more digital valves
60. When multiple digital valves 60 are used, the total flow area
through the plurality of digital valves 60 can be set at a specific
number of total flow areas depending on the position of each
individual digital valve 60. The specific number of total flow
areas can be defined as being 2n flow areas where n is the number
of digital valves 60. For example, in the following description the
shock absorber 20 is described as having four digital valves 60.
The number of total flow areas available would be 24 or sixteen
flow areas, where each flow area influences the damping level of
the shock absorbers 20. Accordingly, with four digital valves 60,
the shock absorber 20 may be controlled to sixteen discrete and
distinct level of damping, as described in further below.
[0046] Furthermore, when multiple digital valves 60 are used, the
flow area of the digital valves may be varied. For example, if two
digital valves 60 are used, one digital valve may have a larger
flow area than the other digital valve. Accordingly, the flow area
provided by the digital valve 60 may be customized by adjusting the
orifice size of the digital valve 60.
[0047] Fluid flow through the digital valve 60 will occur both
during a rebound or extension stroke and during a compression
stroke. During a rebound or extension stroke, fluid in the upper
working chamber 44 is pressurized, which then forces fluid flow
through the digital valve 60 when it is opened. During a
compression stroke, fluid flows from the lower working chamber 46
to the upper working chamber 44 through the piston assembly 32 due
to the "rod volume" concept. When the digital valve 60 is opened,
an open flow path between the upper working chamber 44 and the
reservoir chamber 52 is created. Additional fluid flow will flow
through the piston assembly 32 and through the digital valve 60
because this open flow path creates the path of least resistance to
the reservoir chamber 52 in comparison to flow through the base
valve assembly 38.
[0048] While in the example embodiment the digital valve assembly
60 is positioned at or near the rod guide assembly 50 of the shock
absorber 20, the digital valve 60, may be positioned at other
locations within the shock absorber 20. In particular, further
details regarding the shock absorber 20 and the digital valve 60,
is further described in Applicant's commonly owned U.S. Pat. No.
8,616,351 for "Damper With Digital Valve" which issued Dec. 31,
2013, the disclosure of which is incorporated herein.
[0049] The shock absorber 20 further includes a damper module 100.
The damper module 100 may be disposed with the shock absorber 20 in
a separate housing (not shown). The damper module 100 controls the
positions of the digital valves 60 disposed within the shock
absorbers 20 to adjust the dampening characteristics of the shock
absorber 20. The shock absorber 20 and the damper module 100 may be
referred to together as a damping system.
[0050] The damper module 100 may receive a damper setting from a
master module 102. The master module 102 is disposed in the vehicle
10 (FIG. 1). The master module 102 is communicably coupled to the
damper module 100 of each of the shock absorbers 20 disposed in the
vehicle 10.
[0051] With reference to FIG. 4, an example of a vehicle damper
system 103 is shown. The master module 102 receives data from
various sensors 104 disposed at or near the shock absorbers 20
and/or disposed at other positions of the vehicle 10. The sensors
104 may include but are not limited to an angular rate sensor, an
inertial measurement unit (IMU), a temperature sensor, a height
sensor, a pressure sensor, an accelerometer, and other suitable
sensors that provide data used for controlling the dampening
characteristics of the shock absorber 20.
[0052] The master module 102 may also receive information from
other modules disposed in the vehicle 10 via a vehicle network 106.
The vehicle network 106 may be a controller area network (CAN), a
local interconnect network (LIN), or other suitable networks. The
master module 102 may receive for example, information regarding
the rotation of the steering wheel from a steering wheel position
sensor via the vehicle network 106.
[0053] Based on the inputs received, the master module 102
determines a damper setting for each of the shock absorbers 20.
Specifically, the master module 102 may include a series of
algorithms in the form of computer executable programs that
determine the damper setting based on the inputs received. The
damper setting is provided to the damper module 100 of each of the
shock absorbers 20. In addition, the master module 102 may provide
the information received from the sensors 104 and/or the vehicle
network 106 to the damper module. For example, the damper module
100 may receive data related to the temperature of the shock
absorber or an acceleration of the vehicle. In the example
embodiment the master module 102 is disposed separately from the
damper module 100. Alternatively, the master module 102 may be
disposed with the damper module 100, such that each damper module
100 includes a master module.
[0054] With reference to FIG. 5, an example of the damper module
100 is presented. The damper module 100 may include a valve
switching module 108 and a coil activation module 110. Based on the
damper setting, the valve switching module 108 determines a damping
state of the shock absorber 20. For example, with four digital
valves 60, the shock absorber 20 may have sixteen discrete and
distinct levels of damping which range from soft to firm.
[0055] The valve switching module 108 may include a table that
correlates the damping state with a position or valve state of each
of the digital valves 60 provided in the shock absorber 20. For
example, with reference to FIG. 6, the four digital valves 60 may
be identified in the table as #1, #2, #3, and #4. For each of the
damping states, the valve state of the digital valve 60 may be
defined as "OFF" or "ON". In an OFF-state the coil assembly 70 of
the digital valve 60 does not receive power and is in the first
position. Conversely, in an ON-state, the coil assembly 70 receives
power such that the digital valve 60 is in the second position. As
illustrated in FIG. 6, for a damping state, all of the digital
valves 60 are in the OFF-state. Alternatively, to achieve a seventh
damping state, the #1-digital valve 60 (#1) and the #4-digital
valve 60 (#4) are in the OFF-state and the #2-digital valve 60 (#2)
and #3-digital valve 60 (#3) are in the ON-state.
[0056] The damper setting received by the damper module 100 is a
target state of the shock absorber 20. The valve switching module
108 compares the target state with a present state of the shock
absorber 20 which is the present damping state of the shock
absorber 20. If the target state is different from the present
state, the valve switching module 108 may refer to the target state
as a desired state.
[0057] Based on the target state and the present state, the valve
switching module 108 determines a control operation of the digital
valve 60. Specifically, the valve switching module 108 determines
whether control operation of the digital valve 60 is in an
actuation operation, a hold operation, or an off operation. With
reference to FIG. 7, in the actuation operation of the digital
valve 60, an electrical current pulse (i.e., actuation pulse) is
applied to move the digital valve 60 from the first position to the
second position via the coil assembly 70 (i.e., ON-state).
Accordingly, the actuated position of the digital valve 60 can
correspond to either the hydraulically opened or closed condition
depending on the mechanical configuration of the digital valve
60.
[0058] During the hold operation, an electrical current pulse
having a lower steady state level than the actuation pulse can be
applied to keep the digital valve 60 in the ON-state. Specifically,
after the digital valve 60 is actuated, the hold operation can be
performed to maintain the digital valve 60 in the ON-state.
Alternatively, if the digital valve 60 includes a means for
retaining the digital valve 60 in its second position, as described
above, no electrical current pulse is applied to the coil assembly
70 during the hold operation.
[0059] The off-operation deactivates the digital valve 60. For
example, current may no longer be provided to the digital valve 60.
Accordingly, the digital valve 60 moves from the second position to
the first position, and the digital valve 60 is in the OFF-state.
Alternatively, if the digital valve 60 includes a means for
retaining the digital valve 60 in its second position, as described
above, during the off-operation a reverse current or reverse
polarity of power may be supplied to the coil assembly 70 to
overcome the retaining means.
[0060] The digital valve 60 of the shock absorber 20 is
electrically coupled to the coil activation module 110 via the coil
assembly 70 (represented by dotted line in FIG. 5). The valve
switching module 108 provides the control operation to the coil
activation module 110 which then operates the coil assembly 70
accordingly. For example, if the digital valve 60 is to be
actuated, the coil activation module 110 provides the activation
current pulse to the coil assembly 70 of the digital valve 60.
[0061] To provide a fast, smooth, and power efficient switching of
the damper state from the present state to the desired state, the
valve switching module 108 may control a switch time and/or
transition period during which the digital valve 60 shifts from the
present state to the desired state. Specifically, valve switching
can be used to create a faster hydraulic response. The valve
switching module 108 includes various types of switching methods to
help alleviate delays inherent with fluid dynamics.
[0062] The switching methods may also minimize hydraulic pressure
transients associated with changing the firmness setting during
dynamic operation of the damper system. The switching methods are
intended to provide smooth transitions during hydraulic changes in
the damper system. Accordingly, vehicle noise, vibration, and
harshness (NVH) can be optimized by utilizing the switching methods
described here.
[0063] Furthermore, the peak current required for actuating the
digital valves 60 can be reduced by utilizing the switching methods
that minimize the number of digital valves 60 switched or by
creating time offsets between actuation pulses. The switching
methods provided by the valve switching module 108 may be separated
into two categories: valve staggering control and state transition
control.
[0064] The valve staggering control refers to a method in which a
transient state may be used between the present state and the
desired state. The transient state, which may also be referred to
as transient intermediate state, is one or more damping states
different from the present state and the desired state that are
achieved prior to the desired state (i.e., the target state). One
goal of the transient state is to reduce the peak current
requirement. Specifically, short time delays (e.g., 1-2
milliseconds) may be added between the actuation operations of the
digital valves 60. For example, as shown in FIG. 8, actuation
pulses 120, 122, 124 are staggered. Time delays prior to switching
the digital valves 60 to the OFF-state are not necessary.
[0065] One type of valve staggering control is a basic delay
staggering. During the basic delay staggering a short delay is
provided prior to the actuation of certain digital valves 60. The
valve switching module 108 identifies which of the digital valves
60 to immediately actuate and which to delay. For example, when the
shock absorber includes four digital vales, the valve switching
module 108 may immediately actuate two of the digital valves 60,
followed by the other two after a short delay. Accordingly, the
valve switching module 108 may predefine the digital valves 60 that
are to be delayed.
[0066] With reference to FIG. 9, an example of the basic delay
staggering is presented. The graph illustrates switching from
damping state 1 to states 2-16. The right side of the graph
illustrates the valve position for the digital valves 60 defined in
FIG. 6. For example, in FIG. 6, the ON-state is represented by "1"
and the OFF-state is represented by "0". Accordingly, for state 1,
the valve state is "0000". Similarly, for state 4, the valve state
is "0011". In the four digit binary valve, values from left to
right represent the valve state of #1-digital valve 60, #2-digital
valve, #3-digital valve, and #4-digital valve. Thus, for state 4,
#1-digital valve 60 and the #2-digital valve 60 are in the
OFF-state (i.e., "00") and the #3-digital valve 60 and the
#4-digital valve 60 are in the ON-state (i.e., "11").
[0067] As shown in FIG. 9, if the present state is state 1 (0000)
and the target state is state 7 (0110), #2-digital valve 60 is
actuated first, then after a small delay, #3-digital valve 60 is
actuated. Based on the basic delay staggering, one transient state
is provided between the present and target state. Meaning, from the
present state (0000) to the target state (0110), the damping state
changes from 0000 (present state) to 0100 (transient state) to 0110
(target state). Per FIG. 9, a transient state is used in about 80%
of the possible transition scenarios.
[0068] Another type of valve staggering control is a smart delay
staggering. Similar to the basic delay staggering, the smart delay
staggering provides a short delay prior to actuation of certain
valves. However, in the smart delay staggering identification of
which digital valves 60 to immediately actuate is determined based
on which of the digital valves 60 need to be switched to achieve
the target state. In other words, unlike the basic delay
staggering, the valve switching module 108 does not predefine the
digital valves to delay. The valve switching module 108 determines
which valves are to be actuated based on the present state and the
target state, and actuates one or more digital valves first,
followed by other digital valves after the short delay if
needed.
[0069] With reference to FIG. 10, an example of the smart delay
staggering is presented. In particular, FIG. 10 illustrates
switching from state 1 to states 2-16. In the example, the first
and the second digital valves 60 that need to be switched are
actuated immediately, followed by the third and fourth valves after
the short delay. For example, if the present state is state 1
(0000) and the target state is state 12 (1011), the valve switching
module 108 determines that #1, #3, and #4 digital valves 60 are to
be actuated to reach state 12 (1011).
[0070] Using the smart delay staggering, #1 and #3 digital valves
60 are actuated first, and after a short delay, the #4 digital
valve is turned on. The smart delay staggering may create one
transient state in between the present and the target state if
needed. Meaning, from the present state (0000) to the target state,
such as state 12, the damping state changes from 0000 (present
state) to 1010 (transient state) to 1011 (target state). As shown
in FIG. 10, an intermediate state is used in about one third of the
possible transition scenarios.
[0071] The flow area of the digital valves 60 may be used to define
which digital valve 60 is to be delayed (the basic delay
staggering) and/or which digital valve 60 is to be actuated based
on the target state (smart delay staggering). Accordingly, for the
basic staggering, the digital valves 60 that that have the smaller
flow area may be identified by the valve switching module 108 as
the digital valves 60 to delay. Similarly, when the smart delay
staggering determines the digital valves 60 that are to be actuated
to reach the target state, the digital valves 60 that have the
larger flow area are actuated first followed by the digital valves
60 with the smaller area.
[0072] As another variation, the valve staggering control may
include a flow-area staggering. Flow-area staggering is similar to
the smart delay staggering in that it determines which digital
valves 60 are to be actuated based on the target state. Flow-area
staggering also progresses the actuation of the digital valves 60
to be actuated from the digital valve 60 with the largest flow area
to the digital valve 60 with the smallest flow area and providing
short delays in between actuation of each digital valve 60.
Flow-area staggering provides for the lowest peak current
requirement because only one valve is switched at a time.
[0073] With reference to FIG. 11, an example operation of the
flow-area staggering method is presented. The example of FIG. 11
illustrates switching from state 1 to states 2-16. Based on the
flow-area staggering method, the digital valve 60 with the largest
flow area that needs to be switched is actuated immediately,
followed sequentially by the other digital valves 60 after short
delays. For example, if the present state is state 1 (0000) and the
target state is state 8 (0111), the valves switching module 108
determines that #2, #3, and #4 digital valves 60 are to be actuated
to reach the target state. Under the flow-area staggering method,
the #2-digital valve 60 is actuated first. After a small delay,
#3-digital valve 60 is actuated followed by, after a small delay,
#4-digital valve 60.
[0074] Accordingly, between the present state and the target state,
the damping state enters two transient states. Meaning, the damping
state changes from 0000 (present state) to 0100 (transient state)
to 0110 (transient state) to 0111 (target state). Based on FIG. 11,
up to three transient states can be created between the present
state and the target state.
[0075] A digital valve that is actuated first may be referenced as
a primary valve and a digital valve that is actuated after the
primary valve may be referenced to as a non-primary valve or
secondary valve. It is readily understood that the digital valves
may be switched or actuated in one or more groups with a delay
disposed between each group.
[0076] In addition to valve staggering control, the switching
methods provided by the valve switching module 108 may also include
state transition control. State transition control may be used in
parallel with valve staggering control. Multiple state transition
controls described herein may also be used together. One of the
goals of the state transition control is to optimize response time
and NVH. State transition control, like valve staggering control,
also uses additional states and delays; however the delays can be
substantially longer. For instance, delays may be between 5-100
milliseconds for state transition control.
[0077] Without the state transition control, the damping state is
switched immediately to the target state. In other words, there is
no transition control in this mode. One type of state transition
control is the fixed-step control in which the damping state
transitions from the present state to the target state in a fixed
number of steps defined by "m" where m is an integer. Accordingly,
to transition from the present state to the target state, the
transient state is every mth state.
[0078] With reference to FIG. 12, an example operation of the
fixed-step control is illustrated. In FIG. 12, the present state is
provided as state 3, and the target state is state 13. If there is
no fixed state size (i.e., immediate switch), the damping state is
switched immediately from state 3 to state 13. If the m=4, the
damping state changes to every fourth state. Thus, from state 3 the
damping state changes to state 7, then to state 11 before reaching
the target state of state 13.
[0079] Under the fixed-step control, a determination may be made to
ensure that the target state is not passed. For example, the
fixed-step control may determine if the number of damping states
between a present damping state and the target damping state is
less than the fixed number of steps (m). If it is, the fixed-step
control adjusts the damping state to the target state. Accordingly,
when m=4, the damping state was switched from state 11 to the
target state of state 13. In addition, as the fixed number of steps
decreases, the time in which it takes to reach the target state
from the present state increases. Thus, the delay between the
present state and the target state varies in the fixed-step
control.
[0080] Another type of state transition control is a fixed
transition time. In the fixed transition time, switch from the
present state to the target state is performed in a preset amount
of time. In other words, the time taken to reach a target state
from a present state is the same regardless of the target state.
For example, FIG. 13 illustrates the fixed transition time for
different target states. In the example shown, the present state is
state 3, and different lines shows the transition to a different
target state, such as states 5, 8, 13, and 16. Based on the graph,
the time taken to reach state 5 from state 3 is approximately the
same as from state 3 to state 16.
[0081] Various switching methods, as descried herein, can be used
with the fixed transition time to determine which transient states
are used to reach the target state within the fixed transition
time. For example, the valve staggering controls, as described
above, may be used to switch from the present state to the target
state within the fixed transition time.
[0082] The state transition control also includes an overdrive
control. Under the overdrive control, a damping state that is
beyond the target state is provided as the transient state, and
following a delay, the damping state is switched to the target
state. One of the goals of the overdrive control is to achieve a
faster hydraulic response. For example, FIG. 14 illustrates two
overdrive controls. If the present state is state 3 and the target
state is state 13, the fast overdrive control switches from state 3
(present state) to 16 (transient state) to 13 (target state). For
the slow overdrive control, the damping state switches from 3
(present state) to 16 (transient state) to 15 (transient state) to
14 (transient state) to 13 (target state).
[0083] Accordingly, the overdrive control switches the damping
state to a state beyond the target state before switching to the
target state. In addition, the time in which the overdrive control
performs the switch may be preset to allow for the fast or slow
control.
[0084] The state transition control further includes a PID control.
The PID control is based on known proportional-integral-derivative
algorithms that calculate an error value as the difference between
the target state and the present state. Also known as classical PID
control, the number of transient states is based on the sum of
calculations of the proportional, integral, and derivative values
of the error. Individual multipliers ("gains") for proportional,
integral, and derivative terms are used as the PID control. FIG. 14
illustrates a PID control for switching from state 3 (present
state) to state 13 (target state).
[0085] Similar to classical PID, the state transition control also
includes a quadratic control. The quadratic control uses a
quadratic multiplier term consisting of the square of the error
between the target state and the present state. The quadratic
multiplier term replaces the derivative term. Quadratic control may
be referred to as PIQ control. Quadratic transition control is
meant to be a performance improvement to linear proportional
control by using larger state changes with larger errors and
smaller state changes with smaller error values. FIG. 14
illustrates the quadratic control for switching from state 3
(present state) to state 13 (target state).
[0086] The state transition control also includes an asymmetric
control in which switching delays are set separately for the
increasing and decreasing directions of damping state transitions.
For example, FIG. 15 provides four examples in which the asymmetric
control is used to transition between state 3 and state 13. In
examples 1 and 3, the time taken to transition from state 13 to
state 3 is less than the time taken to transition from state 3 to
state 13. Whereas in examples 2 and 4, the time taken to transition
from state 13 to state 3 is more than the time taken from state 3
to state 13. For performing the asymmetrical control, the valve
switching module 108 may include a predefined logic table that
defines the switching delays for the increasing and decreasing
directions of damping state transitions.
[0087] In the examples provide thus far of the state transition
controls, the transition between the present state to the target
state includes switching to a discrete damping state. As part of
the state transition controls, a fractional stepping control (i.e.,
pulse mode operation) creates a virtual position between the
discrete damping states. The pulse mode operation creates the
virtual positions by pulse modulation or fast switching between two
positions.
[0088] One way to implement the pulse mode operation is by
repeating the actuation pulse without the corresponding hold
current applied. Specifically, the virtual position between two
discrete damping states (i.e., two adjacent damping states) can be
created by operating one or more valves in between the "OFF" and
"ON" valve states. This can be achieved with pulse mode operation
by oscillating between the "OFF" and "ON" valve states. The new
states may be referred to as fractional states.
[0089] Another method involves pulse width modulation (PWM) control
which is similar to micro-stepping in a stepper motor. Half
stepping or micro-stepping with finer resolution is possible. PWM
control is used as a transient method to improve NVH. Continuous
pulse mode operation may generate excessive heat and power
consumption. Pulse mode operation may be used in parallel with
other state transition controls such as fixed step, PID, or
quadratic control, as illustrated in FIG. 16.
[0090] In addition to valve staggering control and state
transition, the valve switching module 108 may include other
switching methods for improving the performance of the shock
absorber 20. For example, in a synchronization control, a delay may
be provided before turning off a hold current or before the
actuation current pulse. Accordingly, the timing of hydraulic
pressure discontinuities created by actuation of other digital
valves or turning off other digital valves is matched or
synchronized.
[0091] In a repeat actuation control, an actuation current pulse is
applied to a coil associated with a digital valve 60 that is
already intended to be in the ON-state. Repeat actuation control
ensures that the target damper state is set. Specifically, there is
a possibility that the digital valve 60 may not engage or stay in
the ON-state due to, for example, excessive electromagnetic
interference, contamination, high viscosity oil associated with low
temperatures, low viscosity oil associated with high temperatures,
and/or very high acceleration impact from an external source such
as driving through a pothole. Accordingly, the repeat actuation
control performs as a mitigating action for preventing a fault.
[0092] As a form of repeat actuation control, an actuation current
pulse may be periodically applied to the digital valve 60 that is
to be in the ON-state. For example, the valve switching module 108
may have the coil activation module periodically apply the
actuation current based on a preset timer. The periodic application
of the actuation current should be done sparingly to avoid
generation of extra heat. For example, the preset timer may be set
in the range of every 1-100 seconds.
[0093] As a form of repeat actuation control, an actuation current
pulse can be applied when the measured temperature is above or
below preset values. Such a control ensures that the shock absorber
is performing at the intended damping state during extreme high or
low temperature operation. For example, the temperature may be the
temperature of the shock absorber, the fluid within the shock
absorber a temperature of the housing in which the damper module
100 is disposed, or a combination of temperatures that indicate the
temperature at which the shock absorber is performing. Temperature
based repeat actuation might be in the range of every 1-100
seconds.
[0094] As a form of repeat actuation control, an actuation current
pulse can be applied when the measured or calculated acceleration
exceeds a preset value. Such a control ensures that the shock
absorber 20 is set at the intended damping state following an
impact load. For example, the acceleration may be provided by an
accelerometer disposed at or near the shock absorber 20 and/or may
be a combination of accelerations. One or more actuation pulses may
be applied to each coil following a high acceleration.
[0095] The valve switching module 108 may also include warm-up
controls to electrically heat the coils, valves, and oil at low
temperatures. For example, an actuation current pulse may be
applied when the measured temperature is below a preset value. The
purpose is to generate additional heat to warm the digital valve 60
and the fluid within the shock absorber 20. The actuation current
pulse may be applied in the range of every 5-500 milliseconds.
[0096] As another form of the warm-up control, a continuous maximum
(un-modulated) current may be applied when the measured temperature
is below the preset value. Alternatively, the hold current (or
another modulated current level) without the actuation pulse may be
applied when the measured temperature is below the preset
value.
[0097] A vehicle-level staggering delay may be used to reduce the
peak current requirement. In other words, the shock absorbers 20
disposed at the corners of the vehicle can be controlled, such that
the shock absorbers 20 do not switch at the same time to their
respective damping states. One method of performing such control is
by adding a short time delay between the commands sent by the
master module 102 to each of the shock absorbers 20. Staggering
delays might typically be 1-2 milliseconds. Commands may be delayed
to individual corner shock absorbers of the vehicle or commands may
be sent in sets of two. For example, sets of two may consist of the
two front suspension 14 shock absorbers 20 and the rear suspension
12 shock absorbers 20.
[0098] The damper module 100, which includes the valve switching
module 108 and the coil activation module 110, may use one or more
of the switching methods described herein for actuating the digital
valves 60. For example, the damper module 100 may include a set of
algorithms and/or predefined tables that define the switching
method to be used for actuating the digital valves.
[0099] While the switching methods were described with regard to a
shock absorber having four digital valves 60, it is within the
scope of this disclosure to apply the switching methods to shock
absorbers having two or more digital valves 60.
[0100] With reference to FIG. 17, a flowchart of an example method
200 for performing a valve switching operation is presented. The
damper module 100, at 202 determines whether the damper setting has
been received. For example, the damper module 100 may receive the
damper setting from the master module 102. If the damper setting
has not been received, the damper module returns to 202. If the
damper setting has been received, the damper module 100 determines
the target state (target damping state) of the shock absorber 20
based on the damper setting at 204.
[0101] At 206, the damper module 100 determines whether the present
state is equal to the target state. If the present state is equal
to the target state, the damper module 100 continues to 208. If the
present state is not equal to the target state, the damper module
100 performs a predefined switching method to change the present
state to the target state at 210. The switching method can be any
one or more of the switching methods described above. For example,
the switching method may be a combination of the smart delay
staggering and the asymmetric control. After the switching method,
the damper module 100 returns to 202.
[0102] At 208 the damper module 100 may maintain the power supply
to the digital valves 60. For example, if digital valve 60 is in
the second position a hold current may be applied to maintain the
digital valve 60 in the second position. Although not shown, when
maintaining the digital valves 60 at the present damping state, the
damper module 100 may periodically actuate the digital valves that
are in the second position. For example, the damper module 100 may
perform a warm-up control to increase the temperature of the damper
system, as described herein. The damper module 100 may also perform
the repeat actuation control to ensure the digital valves 60, which
are supposed to be in the second position, are in the ON-state.
From 208, the damper module 100 returns to 202.
[0103] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure. In this application,
including the definitions below, the term module may be replaced
with the term circuit.
[0104] The term module may refer to, be part of, or include an
Application Specific Integrated Circuit (ASIC); a digital, analog,
or mixed analog/digital discrete circuit; a digital, analog, or
mixed analog/digital integrated circuit; a combinational logic
circuit; a field programmable gate array (FPGA); a processor
(shared, dedicated, or group) that executes code; memory (shared,
dedicated, or group) that stores code executed by a processor;
other suitable hardware components that provide the described
functionality; or a combination of some or all of the above, such
as in a system-on-chip.
[0105] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments of the present disclosure. It
will be apparent to those skilled in the art that specific details
need not be employed, that example embodiments may be embodied in
many different forms and that neither should be construed to limit
the scope of the disclosure. In some example embodiments,
well-known processes, well-known device structures, and well-known
technologies are not described in detail.
[0106] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore 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. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
[0107] When an element or layer is referred to as being "on,"
"engaged to," "connected to," or "coupled to" another element or
layer, it may be directly on, engaged, connected or coupled to the
other element or layer, or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly engaged to," "directly connected to," or
"directly coupled to" another element or layer, there may be no
intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0108] Although the terms first, second, third, etc. may be used
herein to describe various elements, components, regions, layers
and/or sections, these elements, components, regions, layers and/or
sections should not be limited by these terms. These terms may be
only used to distinguish one element, component, region, layer or
section from another region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first element, component, region, layer or section
discussed below could be termed a second element, component,
region, layer or section without departing from the teachings of
the example embodiments.
[0109] Spatially relative terms, such as "inner," "outer,"
"beneath," "below," "lower," "above," "upper," and the like, may be
used herein for ease of description to describe one element or
feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Spatially relative terms may be
intended to encompass different orientations of the device in use
or operation in addition to the orientation depicted in the
figures. For example, if the device in the figures is turned over,
elements described as "below" or "beneath" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example term "below" can encompass both an
orientation of above and below. The device may be otherwise
oriented (rotated 90 degrees or at other orientations) and the
spatially relative descriptors used herein interpreted
accordingly.
* * * * *