U.S. patent application number 13/651417 was filed with the patent office on 2013-05-16 for ground fault interrupt circuit for electric vehicle.
The applicant listed for this patent is Scott BERMAN, Albert FLACK. Invention is credited to Scott BERMAN, Albert FLACK.
Application Number | 20130119933 13/651417 |
Document ID | / |
Family ID | 44799040 |
Filed Date | 2013-05-16 |
United States Patent
Application |
20130119933 |
Kind Code |
A1 |
FLACK; Albert ; et
al. |
May 16, 2013 |
GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC VEHICLE
Abstract
In one implementation, a ground fault interrupt circuit is
provided for a utility power connection to an electric vehicle
charging unit. The ground fault interrupt circuit may include a
gain amplifier having an input connected to be capable of receiving
a differential current from a current sensing transformer and a
comparator having an input connect to a reference voltage. It
includes a rectifier circuit connected between the gain amplifier
and the comparator with a charge accumulator circuit coupled
between the rectifier and the comparator.
Inventors: |
FLACK; Albert; (Lake
Arrowhead, CA) ; BERMAN; Scott; (Los Angeles,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FLACK; Albert
BERMAN; Scott |
Lake Arrowhead
Los Angeles |
CA
CA |
US
US |
|
|
Family ID: |
44799040 |
Appl. No.: |
13/651417 |
Filed: |
October 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2011/032576 |
Apr 14, 2011 |
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13651417 |
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61324296 |
Apr 14, 2010 |
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61374612 |
Aug 18, 2010 |
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61324293 |
Apr 14, 2010 |
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Current U.S.
Class: |
320/109 ; 361/46;
361/50 |
Current CPC
Class: |
B60L 3/0069 20130101;
B60L 3/00 20130101; H02H 9/08 20130101; H03F 1/3235 20130101; H02J
7/0029 20130101; H03F 3/45 20130101 |
Class at
Publication: |
320/109 ; 361/50;
361/46 |
International
Class: |
H02J 7/00 20060101
H02J007/00; H02H 9/08 20060101 H02H009/08 |
Claims
1. A ground fault interrupt circuit for a utility power connection
to an electric vehicle charging unit, the ground fault interrupt
circuit comprising: a) a gain amplifier having an input connected
to be capable of receiving a differential current from a current
sensing transformer; b) a filter having an input connected to an
output of the gain amplifier; c) a comparator having an input
connected to an output of the half wave rectified dual stage
filter; d) a fault latch having an input connected to the output of
the comparator; e) a contactor control circuit having an input
connected to an output of the fault latch; and f) a utility power
line contactor having a contactor control input connected to an
output of the contactor control circuit.
2. The circuit of claim 1, wherein the filter is a half wave
rectified dual stage filter.
3. The circuit of claim 1, wherein the gain amplifier comprises a
surge protection circuit, and further comprising a redundant surge
protection circuit connected to an input of the gain amplifier.
4. The circuit of claim 3, wherein the redundant surge protection
circuit comprises a pair of diodes connected to lower and upper
reference busses.
5. The circuit of claim 1, further comprising a microprocessor
connected to the output of the fault latch so as to detect a fault
trip, and to a fault latch reset input of the fault latch.
6. The circuit of claim 1, wherein the contactor control circuit
further comprises a contactor control relay, the contactor control
relay is connected to the utility power line contactor.
7. The circuit of claim 6, further comprising a contactor disable
latch responsive to the output of the comparator, the contactor
disable latch being connected to an input of the contactor control
circuit in parallel with the output of fault latch so as to provide
a redundant control signal for controlling the contactor control
relay.
8. The circuit of claim 1, further comprising a differential
current sensing transformer coupled to utility power lines.
9. A method for electric vehicle charging for detecting a ground
fault comprising: detecting a differential current in utility power
supply; generating a ground fault signal from the detected
differential current; accumulating the ground fault signal over
time; and comparing the accumulated ground fault signal to a
threshold voltage; and causing a ground fault interrupt when the
accumulated ground fault signal exceeds the threshold voltage.
10. The method of claim 9, wherein accumulating the ground fault
signal over time comprises filtering the ground fault signal.
11. The method of claim 10, wherein filtering the ground fault
signal comprises using a double stage filter.
12. The method of claim 11, wherein filtering the ground fault
signal comprises using a half wave rectifying double stage
filter.
13. The method of claim 9, wherein accumulating the ground fault
signal over time comprises accumulating ground fault signals having
a voltage level below the threshold voltage so as to cause the
ground fault interrupt at the threshold voltage.
14. The method of claim 9, wherein accumulating the ground fault
signal over time comprises accumulating multiple discrete signals
having a voltage level below the threshold voltage so as to cause
the ground fault interrupt at the threshold voltage.
15. The method of claim 14, wherein accumulating the ground fault
signal over time and causing the ground fault interrupt comprises
causing the ground fault interrupt when the multiple discrete
signals have a duration that is less than a duty cycle.
16. The method of claim 9, wherein generating the ground fault
signal from the detected differential current comprises using a
gain amplifier.
17. The method of claim 9, comprising latching a ground fault
interrupt signal when the accumulated ground fault signal exceeds
the threshold voltage.
18. The method of claim 9, comprising opening a utility power line
contactor when the accumulated ground fault signal exceeds the
threshold voltage.
19. The method of claim 9, further comprising generating an
inverted ground fault signal, and wherein accumulating further
comprises accumulating both the ground fault signal and the
inverted ground fault signal over time.
20. The method of claim 19, further comprising rectifying and the
ground fault signal and the inverted ground fault signal prior to
accumulating.
21. The method of claim 19, wherein generating the ground fault
signal comprises generating the ground fault signal about a
reference voltage, and wherein generating the inverted ground fault
signal comprises generating the ground fault signal about the
reference voltage.
22. The method of claim 21, further comprising rectifying and the
ground fault signal and the inverted ground fault signal prior to
accumulating.
23. A method for electric vehicle charging for detecting a ground
fault comprising: detecting a differential current in utility power
supply; generating a ground fault signal from the detected
differential current; filtering the ground fault signal; and
comparing the filtered ground fault signal to a threshold voltage;
and disconnecting the utility power supply when the filtered ground
fault signal exceeds the threshold voltage.
24. The method of claim 23, wherein filtering the ground fault
signal comprises using a half wave rectifying double stage
filter.
25. The method of claim 23, comprising generating a latched fault
signal when the filtered ground fault signal exceeds the threshold
voltage.
26. The method of claim 25, comprising opening a utility power
contactor to disconnect the utility power supply in response to the
latched fault signal.
27. The method of claim 26, wherein generating the latched fault
signal comprises generating a ground fault interrupt fault signal
and generating a contactor fault disable signal, and further
comprising opening the utility power contactor in response to
either the ground fault interrupt fault signal or the contactor
fault disable signal.
28. A ground fault interrupt circuit for a utility power connection
to an electric vehicle charging unit, the ground fault interrupt
circuit comprising: a) a gain amplifier having an input connected
to be capable of receiving a differential current from a current
sensing transformer; b) a comparator having an input connect to a
reference voltage; c) a rectifier circuit connected between the
gain amplifier and the comparator; and d) a charge accumulator
circuit coupled between the rectifier and the comparator.
29. The circuit of claim 28 further comprising an inverter
connected between the gain amplifier and the rectifier circuit.
30. The circuit of claim 28, further comprising an inverter having
an input connected to an output of the gain amplifier, and wherein
the rectifier circuit is a full wave rectifier circuit connected to
the output of the gain amplifier and to an output of the inverter,
and wherein an output of the full wave rectifier circuit is
connected to the charge accumulator circuit.
31. The circuit of claim 28, wherein the charge accumulator
comprises the rectifier circuit, and wherein the rectifier circuit
is a half wave rectifier circuit connected to the gain
amplifier.
32. The circuit of claim 28 further comprising an EMI protection
circuit at an input of the ground fault interrupt circuit.
33. The circuit of claim 32 wherein the EMI protection circuit
comprises an inductor and a resistor connected in series, and at
least one capacitor connected across the differential input and to
ground.
34. The circuit of claim 28 further comprising a fault latch having
an input connected to an output of the comparator.
35. The circuit of claim 34 further comprising a contactor control
circuit having an input connected to an output of the fault
latch.
36. The circuit of claim 35, further comprising a utility power
line contactor having a contactor control input.
37. The circuit of claim 36 further comprising an inverter having
an input connected to an output of the gain amplifier, and wherein
the rectifier circuit is a full wave rectifier circuit connected to
the output of the gain amplifier and to an output of the inverter,
and wherein an output of the full wave rectifier circuit is
connected to the charge accumulator circuit.
38. The circuit of claim 36, wherein the charge accumulator
comprises the rectifier circuit, and wherein the rectifier circuit
is a half wave rectifier circuit connected to the gain amplifier.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of PCT/US2011/032576 by
Flack et al., entitled GROUND FAULT INTERRUPT CIRCUIT FOR ELECTRIC
VEHICLE, filed on 14 Apr. 2011, herein incorporated by reference in
its entirety, which claims the benefit of the following U.S.
Provisional Patent Applications, which are herein incorporated by
reference in their entireties:
[0002] U.S. Provisional Application 61/324,296, by Albert Flack,
filed 14 Apr. 2010, entitled GROUND FAULT INTERRUPT CIRCUIT FOR
ELECTRIC VEHICLE; U.S. Provisional Application 61/374,612, Albert
Flack, filed 18 Aug. 2010, entitled GROUND FAULT INTERRUPT
AUTOMATIC TEST METHOD FOR ELECTRIC VEHICLE; and
[0003] U.S. Provisional Application 61/324,293, by Albert Flack,
filed 14 Apr. 2010, entitled PILOT SIGNAL GENERATION CIRCUIT.
BACKGROUND
[0004] One way to charge an electric vehicle is to supply the
vehicle with power so that a charger in the vehicle can charge the
battery in the vehicle. If there is a ground fault in the
electrical system in the car and someone is touching car while
grounded, that person could be shocked.
[0005] What is needed to avoid this situation is a ground fault
interrupt or GFI circuit to disconnect the power to the vehicle if
a ground fault is detected.
SUMMARY
[0006] In one implementation, a ground fault interrupt circuit is
provided for a utility power connection to an electric vehicle
charging unit. The ground fault interrupt circuit may include a
gain amplifier having an input connected to be capable of receiving
a differential current from a current sensing transformer and a
comparator having an input connect to a reference voltage. It
includes a rectifier circuit connected between the gain amplifier
and the comparator with a charge accumulator circuit coupled
between the rectifier and the comparator.
[0007] Some embodiments may include an inverter between the gain
amplifier and the charge accumulator circuit.
[0008] In one possible implementation, a GFI circuit is provided
for a utility power connection to an electric vehicle charging
unit. The GFI circuit includes a gain amplifier having an input
connected to be capable of receiving a differential current from a
current sensing transformer. A filter is connected to an output of
the gain amplifier. In various embodiments the filter is a half
wave rectified dual stage filter. A comparator is connected to an
output of the filter. The output of the comparator is connected to
a latching circuit. A contactor control circuit is connected to the
output of the fault latch. The contactor control circuit may
include a contactor control relay. The output of the contactor
control circuit is connected to a utility power line contactor so
as to be capable of connecting/disconnecting utility power. In
various embodiments, a microprocessor is connected to a reset input
of the fault latch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The features and advantages of the present invention will be
better understood with regard to the following description,
appended claims, and accompanying drawings where:
[0010] FIG. 1 shows a schematic view of a cable to connect utility
power to an electric vehicle (not shown) along with some associated
circuitry.
[0011] FIG. 2 shows an enlarged view schematic drawing of the GFI
circuit of FIG. 1.
[0012] FIG. 3 shows a schematic view of a contactor control
circuit.
[0013] FIG. 4 shows an enlarged more complete schematic of the
pilot circuitry shown in partial schematic in FIG. 1.
[0014] FIG. 5 is a partial schematic showing a microprocessor,
which may be used to govern the output of the GFI circuit.
[0015] FIG. 6 shows a simplified plot of an example of possible
charge accumulation by the double stage filter leading to a fault
detection by the comparator.
[0016] FIG. 7 shows a schematic view of an alternate embodiment of
a portion of the GFI circuit of FIG. 2.
DESCRIPTION
[0017] FIG. 1 shows a schematic view of a cable 100 to connect
utility power to an electric vehicle (not shown) along with some
associated circuitry. In the embodiment of FIG. 1, the cable 100
contains L1 and L2 and ground G lines. The cable 100 connects to
utility power at one end 100u and to an electric vehicle (not
shown) at the other end 100c. The electric vehicle (not show) could
have an onboard charger, or the electric vehicle end 100c of the
cable 100 could be connected to a separate, optionally free
standing, charger (not shown). The separate charger (not shown)
would in turn be connected to the electric vehicle for charging
onboard batteries, or other charge storage devices. In other
embodiments not shown, a charger could be integrated into the cable
100.
[0018] The cable 100 contains current transformers 110 and 120. The
current transformer 110 is connected to a GFI circuit 130 which is
configured to detect a differential current in the lines L1 and L2
and indicate when a ground fault is detected. Contactor 140 may be
open circuited in response to a detected ground fault to interrupt
utility power from flowing on lines L1 and L2 to the vehicle (not
shown).
[0019] FIG. 2 shows an enlarged view schematic drawing of the GFI
circuit 130 of FIG. 1. In the embodiment of FIG. 2, the GFI circuit
130 is designed to trip in the 5-20 mA range for GFI in accordance
with the UL 2231 standard.
[0020] A signal provided by current transformer 110 (FIG. 1) at
pins 3 and 4 of the GFI circuit 130 is amplified by op amp 132 to a
voltage reference. That voltage reference is filtered by a double
stage RC filter 134 to eliminate spurious noise spikes.
[0021] Fault current detected by current transformer 110 (FIG. 1)
is converted to voltage by gain amplifier 134 for comparison by
comparator 136. The output of the gain amplifier 132 is filtered
prior to being supplied to the comparator 136 with the double stage
RC filter 134 to remove spurious noise that could cause nuisance
shut downs. Output of comparator 136 is latched with flip-flop 138
so that contactor 140 (FIG. 1) does not close after a fault has
been detected. The comparator 136 provides a GFI_TRIP signal
output, which is an input to the fault latch 138 to produce a
latched GFI_FAULT signal.
[0022] The double stage filter 134 provides a delay so that the
shut-off circuit does not immediately shut off if a fault is
detected. The double stage filter 134 is a half-wave rectified
circuit that allows an incoming pulse width that is less than 50%
in some embodiments, or even as small as about 38% in some
embodiments, to accumulate over time so that it will charge at a
faster rate than it discharges. The double stage filter 134
accumulates charge and acts as an energy integrator. Thus, the GFI
circuit 130 waits a time period before causing shut down. This is
because it is not desirable to have an instantaneous shut down that
can be triggered by noise in the lines L1 or L2, or in the GFI
circuit 130. The GFI circuit 130 should trip only if a spike has
some predetermined duration. In the embodiment shown, that duration
is one to two cycles.
[0023] The filter 134 charges through R102 and R103. When it
discharges, it only discharges through R102, so it charges more
current than it discharges over time. The double stage filter 134
is a half wave rectified circuit due to diode D25.
[0024] Diodes D4 provide surge suppression protection. In typical
embodiments, the gain amplifier 132 may actually have surge
suppression protection. Despite this, diodes D4 are added to
provide external redundant protection to avoid any damage to the
gain amplifier 132. This redundant protection is significant,
because if the gain amplifier 132 is damaged, the GFI protection
circuit 130 may not function, resulting in inadequate GFI
protection for the system. For example, without the redundant surge
suppressing diodes D4, if a power surge were to damage the gain
amplifier 132 so that it no longer provided output, the GFI circuit
130 would no longer be able to detect faults. Since UL 2231 allows
utility power L1 and L2 power to be reconnected after a GFI circuit
detects a ground fault surge, utility power L1 and L2 could
conceivably be reconnected after the gain amplifier 132 had been
damaged. It is significant to note that the diodes D4 are connected
to the upper and lower reference voltage busses of the circuit,
i.e. ground and 3 volts, respectively, so that they can easily
dissipate surge current without causing damage to the circuitry.
Thus, the redundant surge suppression diodes D4 provide an
additional safety feature for the GFI protection circuit 130.
[0025] FIG. 3 shows a schematic view of a contactor control circuit
170. The contactor control circuit 170 opens/closes the contactor
140 (FIG. 1) to disconnect/connect the utility power L1 and L2
from/to the vehicle connector 100c. As discussed above with
reference to FIG. 2, the GFI_TRIP signal is output by the
comparator 136 and is an input to the fault latch 138 to produce
the GFI_FAULT signal. The GFI_FAULT signal output by the fault
latch 138 is an input to the contactor control circuitry 170, shown
in FIG. 3, used to control the contactor control relay K1. The
contactor control relay K1 is used to open/close the contactor 140
(FIG. 1) to disconnect/connect the utility power L1 and L2 from/to
the vehicle connector 100c. The CONTACTOR_AC signal output by the
contactor control relay K1 is connected to the contactor coil 141
(FIG. 1) through pin 1 of the connector 181 (FIG. 1) associated
with the utility present circuitry 180 (FIG. 1).
[0026] The GFI_TRIP signal output by the comparator 136 (FIG. 2) is
not only provided to the contactor control circuit 170 (FIG. 3),
but also is provided as an input to the contactor disable latch
152, shown in FIG. 4 to produce a CONTACTOR_FAULT_DISABLE signal.
FIG. 4 shows an enlarged more complete schematic view of the pilot
circuitry 150 shown in partial schematic in FIG. 1. Additionally,
the contactor disable latch 152 (FIG. 4) is an input to the
contactor control circuitry 170 (FIG. 3) to control the contactor
control relay K1 (FIG. 3). The CONTACTOR_FAULT_DISABLE signal is
used to open the contactor control relay K1 (FIG. 3), which opens
the contactor 140 (FIG. 1) to open circuit/close circuit the
utility power L1 and L2. This provides a redundant circuit for this
important safety control circuit. Further, it requires the reset of
both latches 138 (FIG. 2) and 152 (FIG. 4) to reconnect L1 and L2
utility power to the vehicle connector 100c. This provides further
software redundancy for this important safety control circuit.
[0027] FIG. 5 is a partial schematic showing a microprocessor 500,
which may be used to govern the output of the GFI circuit 130 (FIG.
2). Referring to FIGS. 2 and 5, the GFI_FAULT output signal from
the fault latch 138 is provided as an input at pin 552 to the
microprocessor 500. The microprocessor 500 outputs at pin 538 the
GFI_RESET signal to the GFI circuit 130 to control the reset of the
GFI_circuit 130, in accordance with a predetermined standard, such
as UL 2231. This may be accomplished by outputting the GFI_RESET
signal to the fault latch 138, and to the CONTACTOR_RESET to the
contactor disable latch 152 (FIG. 4).
[0028] Also, the microprocessor 500 may also output at pin 81 the
GFI_TEST signal, which causes a GFI test circuit 139 to simulate a
ground fault for testing the functionality of the contactor 140
(FIG. 1). The GFI test circuit 139 output AC_1 provides a path via
pin 2 of the connector 181 to the contactor coil 141 (FIG. 1) to
exercise the contactor 140.
[0029] Additionally, the microprocessor 500 provides a
CONTACTOR_CLOSE signal output to the contactor close circuit to
close the contactor control relay K1 (FIG. 3).
[0030] FIG. 6 shows a simplified plot 600 of an example of possible
charge accumulation by the double stage filter 134 (FIG. 2) leading
to a fault detection by the comparator 136 (FIG. 2). Referring to
FIGS. 2 and 6, since the double stage filter 134 discharges slower
than it charges, several successive current pulse detections 601,
602, and 603 would be required to cause sufficient charge to
accumulate a voltage level that would cause the comparator to
indicate a GFI_TRIP. Thus, faults by spurious noise can be
minimized. In this simplified example plot, a 1.5 volts pulse of
about 38% of the duty cycle for three successive cycles causes
sufficient charge to accumulate a GFI TRIP signal. Other
embodiments are possible by appropriate selection of the R102,
R103, and C51.
[0031] FIG. 7 is shows a schematic view of an alternate embodiment
730 of a portion of the GFI circuit 130 of FIG. 2. In this
embodiment, the input 730i of the GFI circuit 730 is connected to
gain amplifier 732 via an optional EMI protection circuit 731.
Thus, the signal provided by the current transformer 110 is passed
through the EMI protection circuit 731, which includes series
inductor L7 and resistor R71, of about 50 microHenries and 50 ohms,
respectively, with capacitors C34, C33, C20, each about 0.001
microFarads, coupled across the differential input 730i and coupled
to ground.
[0032] Further, in this embodiment, the input 730i is connected to
the amplifier 732 via a series capacitor C17, of about 10
microFarads, and series resistor R23 (about 50 ohms) to the
inverting input of the amplifier 732. The non-inverting input of
the operational amplifier 732 is referenced to 1.5 volts. The
output of the amplifier 732 is feed back to the inverting input of
amplifier 732 via parallel coupled feedback resistor R24 and an
optional feedback capacitor C15, of about 50K ohms and 0.01
microFarads respectively. The optional capacitor C15 provides
filtering to reduce noise. The output of the amplifier 733 is
provided to the inverting input of amplifier 733 via resistor R18
(about 10K ohms). The non-inverting input of the amplifier 733 is
supplied the reference voltage of 1.5 volts. The output of the
amplifier 733 is feed back via resistor R15 (about 10K ohms). Thus,
the amplifier 733 has a gain of unity so merely provides an
inverted output from that of the gain amplifier 732.
[0033] As such, the series capacitor C17 passes the AC portion of
the differential current input 730i, which is both positive and
negative. The input 730i is referenced to 1.5V by the gain
amplifier 732. The output of the gain amplifier 732 is inverted by
the inverting amplifier 733.
[0034] The output of the amplifier 732 and the output of the
amplifier 733 are connected by diodes D2 and D1, respectively, to
the charge accumulator 734. The diodes D2 and D1 provide a full
wave rectified output (with respect to 1.5V) to the charge
accumulator 734. The anode of diode D2 and the anode of diode D1
form a full wave rectifier circuit and are connected to sum at the
input of the charge accumulator 734. The cathode of diode D2 is
connected to the output of gain amplifier 732 and the cathode of
the diode D1 is connected to the output of the inverting amplifier
733. Thus, in this case, as used herein, the charge accumulator 734
actually "accumulates" depleted charge.
[0035] The charge accumulator 734 includes a series connected
resistor R10 of about 25 k ohms, connected between the diodes D2
and D1 and the non-inverting input of comparator 736. The charge
accumulator 734 further includes resistor R7, of about 1M ohm,
connected between the reference voltage 1.5V and the non-inverting
input to the comparator 736. A capacitor C1, of about 0.1
microFarad is connected between the non-inverting input of the
comparator 736 and ground.
[0036] A reference voltage of 0.5 volts is provided to the
inverting input of the comparator 736 by the R72 and R73 voltage
divider. The resistor R72, of about 20K ohms, is connected between
the reference 1.5V and the inverting input of the comparator 736.
The resistor R73, about 10K ohms is connected between the inverting
input of the comparator 736 and ground.
[0037] The output of the comparator 736 may be supplied
directly/indirectly to the microprocessor 500 (FIG. 5), latch 138
(FIG. 2) or/and latch 152 (FIG. 4), such as discussed above with
reference to FIGS. 2-5.
[0038] It is worthy to note that any reference to "one embodiment"
or "an embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment may be
included in an embodiment, if desired. The appearances of the
phrase "in one embodiment" in various places in the specification
are not necessarily all referring to the same embodiment.
[0039] The illustrations and examples provided herein are for
explanatory purposes and are not intended to limit the scope of the
appended claims. This disclosure is to be considered an
exemplification of the principles of the invention and is not
intended to limit the spirit and scope of the invention and/or
claims of the embodiment illustrated.
[0040] Those skilled in the art will make modifications to the
invention for particular applications of the invention.
[0041] The discussion included in this patent is intended to serve
as a basic description. The reader should be aware that the
specific discussion may not explicitly describe all embodiments
possible and alternatives are implicit. Also, this discussion may
not fully explain the generic nature of the invention and may not
explicitly show how each feature or element can actually be
representative or equivalent elements. Again, these are implicitly
included in this disclosure. Where the invention is described in
device-oriented terminology, each element of the device implicitly
performs a function. It should also be understood that a variety of
changes may be made without departing from the essence of the
invention. Such changes are also implicitly included in the
description. These changes still fall within the scope of this
invention.
[0042] Further, each of the various elements of the invention and
claims may also be achieved in a variety of manners. This
disclosure should be understood to encompass each such variation,
be it a variation of any apparatus embodiment, a method embodiment,
or even merely a variation of any element of these. Particularly,
it should be understood that as the disclosure relates to elements
of the invention, the words for each element may be expressed by
equivalent apparatus terms even if only the function or result is
the same. Such equivalent, broader, or even more generic terms
should be considered to be encompassed in the description of each
element or action. Such terms can be substituted where desired to
make explicit the implicitly broad coverage to which this invention
is entitled. It should be understood that all actions may be
expressed as a means for taking that action or as an element which
causes that action. Similarly, each physical element disclosed
should be understood to encompass a disclosure of the action which
that physical element facilitates. Such changes and alternative
terms are to be understood to be explicitly included in the
description.
[0043] Having described this invention in connection with a number
of embodiments, modification will now certainly suggest itself to
those skilled in the art. The example embodiments herein are not
intended to be limiting, various configurations and combinations of
features are possible. As such, the invention is not limited to the
disclosed embodiments, except as required by the appended
claims.
* * * * *