U.S. patent application number 16/769476 was filed with the patent office on 2021-08-19 for redundant, fault tolerant traction drive axle for vehicle.
This patent application is currently assigned to BAE Systems Controls Inc.. The applicant listed for this patent is BAE Systems Controls Inc.. Invention is credited to Bart W. Mancini.
Application Number | 20210254692 16/769476 |
Document ID | / |
Family ID | 1000005750114 |
Filed Date | 2021-08-19 |
United States Patent
Application |
20210254692 |
Kind Code |
A1 |
Mancini; Bart W. |
August 19, 2021 |
REDUNDANT, FAULT TOLERANT TRACTION DRIVE AXLE FOR VEHICLE
Abstract
A system for a vehicle is disclosed. The system comprises a gear
box. The gear box comprises a first shaft coupled to a first motor
and a second shaft coupled to the second motor and a third shift.
Each shaft extends through a respective pinion. The gearbox has a
first shifter for the first motor and a second shifter for the
second motor. The shifters are configured to selectively engage a
respective pinion to an appropriate shaft as needed. The gear box
further comprises a fourth shaft extending through a first gear and
a second gear and an other pinion. The first gear meshes with a
first pinion. The second gear meshes with a second pinion. The
other pinion meshes with a third pinion and a fourth gear. A
differential is mechanically coupled to the fourth gear and a left
axle shaft and a right axle shaft.
Inventors: |
Mancini; Bart W.; (Newark
Valley, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BAE Systems Controls Inc. |
Endicott |
NY |
US |
|
|
Assignee: |
BAE Systems Controls Inc.
Endicott
NY
|
Family ID: |
1000005750114 |
Appl. No.: |
16/769476 |
Filed: |
September 19, 2019 |
PCT Filed: |
September 19, 2019 |
PCT NO: |
PCT/US19/51871 |
371 Date: |
June 3, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60K 6/547 20130101;
F16H 2057/02034 20130101; B60Y 2400/73 20130101; B60K 6/365
20130101; B60Y 2400/61 20130101; B60L 50/60 20190201; B60K 6/26
20130101; B60K 6/28 20130101; B60L 2210/40 20130101; B60Y 2200/91
20130101; B60K 17/08 20130101; B60K 1/02 20130101; B60Y 2200/92
20130101; F16H 37/0826 20130101 |
International
Class: |
F16H 37/08 20060101
F16H037/08; B60K 6/28 20060101 B60K006/28; B60K 6/26 20060101
B60K006/26; B60K 1/02 20060101 B60K001/02; B60K 6/365 20060101
B60K006/365; B60K 6/547 20060101 B60K006/547; B60L 50/60 20060101
B60L050/60; B60K 17/08 20060101 B60K017/08 |
Claims
1. A system for a vehicle comprising: an energy storage system
configured to supply power to a DC link; a first motor; a second
motor; a first motor inverter coupled to the energy storage system
via the DC link and coupled to the first motor, the first motor
inverter is configured to receive power from the DC link and
provide AC power to the first motor; a second motor inverter
coupled to the energy storage system via the DC link and coupled to
the second motor, the second motor inverter is configured to
receive power from the DC link and supply AC power to the second
motor; a gear box mechanically coupled to the first motor and the
second motor, the gear box comprising: a first shaft coupled to the
first motor, the first shaft extending through a first pinion and
concentric with a third shaft, where the third shaft extends
through a third pinion; a second shaft coupled to the second motor,
the second shaft extending through a second pinion and concentric
with the third shaft, the second pinion having a same tooth count
as the first pinion, the third shaft being independent from the
first shaft and the second shaft; a first shifter associated with
the first shaft and the first motor; and a second shifter
associated with the second shaft and the second motor, the first
shifter is configured to selectively engage the first pinion to the
first shaft, the third pinion to the first shaft or neither the
first pinion nor the third pinion to the first shaft when in a
neutral position, wherein when engaged, either the first pinion or
the third pinion are rotated in synchronization with the first
motor; the second shifter is configured to selectively engage the
second pinion to the second shaft, the third pinion to the second
shaft or neither the second pinion nor the third pinion to the
second shaft when in the neutral position, wherein when engaged,
either the second pinion or the third pinion are rotated in
synchronization with the second motor; the gear box further
comprising: a fourth shaft extending through a first gear and a
second gear and an other pinion, the first gear meshing with the
first pinion, the second gear meshing with the second pinion and
the other pinion meshing with the third pinion, the second gear
having a same tooth count as the first gear, the other pinion
meshing with a fourth gear; a differential mechanically coupled to
the fourth gear and a left axle shaft and a right axle shaft.
2. The system for a vehicle of claim 1, wherein the first shifter
and the second shifter are asynchronously controlled such that one
of the first shifter and the second shifter is engaged with the
respective pinion when the other of the first shifter and the
second shifter is in the neutral position.
3. The system for a vehicle of claim 2, wherein the first motor
inverter and the second motor inverter communicate with each other,
wherein when one of the first shifter and the second shifter is
controlled to switch an engagement of a pinion for the associated
motor, the corresponding motor inverter to the switch informs an
other motor inverter of the first motor inverter and the second
motor inverter of the switch.
4. The system for a vehicle of claim 3, wherein, in response to
receipt of the information of switching, the other motor inverter
of the first motor inverter and the second motor inverter controls
a corresponding motor of the first motor and the second motor to
increase its output from prior to the switch.
5. The system for a vehicle of claim 4, wherein when one of the
first shifter and the second shifter is switched and the one of the
first shifter and the second shifter is in the neutral position,
the corresponding motor inverter receives a motor speed of the
motor associated with the one of the first shifter and the second
shifter not being switched from the other motor inverter of the
first motor inverter and the second motor inverter.
6. The system for a vehicle of claim 5, wherein in response to
receipt of the motor speed, the corresponding motor inverter
controls the motor associated with the one of the first shifter and
the second shifter being switched to match a speed of a gear being
switched based on a preset ratio determined from a tooth count and
a speed of the motor not being switched.
7. The system for a vehicle of claim 3, wherein upon completion of
the switch, a corresponding motor inverter corresponding to the
motor associated with the one of the first shifter and the second
shifter being switched informs the other motor inverter of the
first motor inverter and the second motor inverter of the
completion and an other of the first shifter and the second shifter
is switched based on a propulsion command.
8. The system for a vehicle of claim 1, wherein each of the first
motor inverter and the second motor inverter comprises at least a
voltage sensor and a current sensor coupled to a respective motor
and a processor and wherein the processor is configured to detect a
failure based on a signal from the at least a voltage sensor and a
current sensor.
9. The system for a vehicle of claim 8, wherein when the failure is
detected in one or more of the first motor and the second motor, an
associated shifter of the first shifter and the second shifter is
controlled to move to the neutral position for the motor that was
detected as the failure.
10. The system for a vehicle of claim 1, wherein when a failure is
detected in one or more of the first motor inverter and the second
motor inverter, an associated shifter of the first shifter and the
second shifter is controlled to move to the neutral position.
11. The system for a vehicle of claim 1, wherein the first motor
and the second motor are positioned a distance from an axle, the
distance being greater than a radius of the axle plus a radius of
respective motor of the first motor and the second motor plus a
preset value.
12. The system for a vehicle of claim 1, wherein the vehicle is an
electric vehicle.
13. The system for a vehicle of claim 1, wherein the vehicle is a
hybrid electric vehicle, and wherein the system further comprises a
generator coupled to a generator inverter, the generator inverter
is coupled to the DC link, the generator inverter is configured to
receive AC power from the generator and provide DC power to the DC
link, the generator is coupleable to an engine.
14. The system for a vehicle of claim 1, wherein the vehicle is a
hybrid electric vehicle and wherein the system further comprises a
fuel cell, wherein the fuel cell is coupled to the DC link.
15. The system for a vehicle of claim 2, wherein the asynchronously
control is used during deceleration such that one motor of the
first motor and the second motor is coupled to the fourth gear and
maintains a capability of electric regenerative braking during
shifting.
16. A hybrid or electric vehicle, comprising: an energy storage
system configured to supply power to a DC link; a first motor and a
second motor; a first motor inverter coupled to the energy storage
system via the DC link and coupled to the first motor, wherein the
first motor inverter is configured to receive power from the DC
link and provide AC power to the first motor; a second motor
inverter coupled to the energy storage system via the DC link and
coupled to the second motor, wherein the second motor inverter is
configured to receive power from the DC link and supply AC power to
the second motor; a gear box mechanically coupled to the first
motor and the second motor, the gear box comprising: a first shaft
coupled to the first motor, the first shaft extending through a
first pinion and concentric with a third shaft, where the third
shaft extends through a third pinion; a second shaft coupled to the
second motor, the second shaft extending through a second pinion
and concentric with the third shaft, the second pinion having a
substantially same tooth count as the first pinion, the third shaft
being independent from the first shaft and the second shaft; a
first shifter associated with the first shaft and the first motor;
and a second shifter associated with the second shaft and the
second motor, wherein the first shifter is configured to
selectively engage the first pinion to the first shaft, the third
pinion to the first shaft or neither the first pinion nor the third
pinion to the first shaft when in a neutral position, and wherein
when engaged, either the first pinion or the third pinion are
rotated in synchronization with the first motor; the second shifter
is configured to selectively engage the second pinion to the second
shaft, the third pinion to the second shaft or neither the second
pinion nor the third pinion to the second shaft when in the neutral
position, wherein when engaged, either the second pinion or the
third pinion are rotated in synchronization with the second motor;
the gear box further comprising: a fourth shaft extending through a
first gear and a second gear and an other pinion, the first gear
meshing with the first pinion, the second gear meshing with the
second pinion and the other pinion meshing with the third pinion,
the second gear having a substantially same tooth count as the
first gear, the other pinion meshing with a fourth gear; a
differential mechanically coupled to the fourth gear and a left
axle shaft and a right axle shaft.
Description
FIELD OF THE DISCLOSURE
[0001] This disclosure relates to propulsion systems for a vehicle.
More particularly, this disclosure relates to propulsion systems
having multiple motors coupled to a differential.
BACKGROUND
[0002] Vehicles, such as a bus or truck, may have motors for
propulsion of an axle. A vehicle may have two motors respectively
coupled to different wheels. For example, a vehicle may have a left
motor coupled to a left wheel and a right motor coupled to a right
wheel, where the motors are individually controlled to the
different wheels, e.g., dedicated control. Typically, the motors
are located in the wheel hub and may be coupled with a reduction
gear. However, in this configuration, since the motors are
dedicated to a specific wheel, when one of the motors fails,
mechanical power to the wheel is lost.
[0003] Additionally, the motors may be switched to different gears.
During switching, mechanical power to the wheel is also lost during
switching.
SUMMARY
[0004] Accordingly, disclosed is a propulsion system for a vehicle.
The system comprises an energy storage system configured to supply
power to a DC link, a first motor inverter, a second motor
inverter, a first motor, a second motor, a gear box and a
differential. The first motor inverter is coupled to the energy
storage system via the DC link and coupled to the first motor. The
first motor inverter is configured to receive power from the DC
link and provide AC power to the first motor. The second motor
inverter is coupled to the energy storage system via the DC link
and coupled to the second motor. The second motor inverter is
configured to receive power from the DC link and supplied AC power
to the second motor. The gear box is mechanically coupled to the
first motor and the second motor. The gear box comprises a first
shaft coupled to the first motor and a second shaft coupled to the
second motor. The first shaft and the second shaft are concentric
with a third shaft. The first shaft extends through a first pinion.
The second shaft extends through a second pinion. The third shaft
extends through a third pinion. The second pinion has substantially
the same tooth count as the first pinion. The third shaft is
independent from the first shaft and the second shaft. The gearbox
further has a first shifter for the first motor and a second
shifter for the second motor.
[0005] In an aspect of the disclosure, the first shifter is
configured to selectively engage the first pinion to the first
shaft, the third pinion to the first shaft or neither the first
pinion nor the third pinion to the first shaft when in a neutral
position. When engaged, either the first pinion or the third pinion
rotated in synchronization with the first motor.
[0006] In an aspect of the disclosure, the second shifter is
configured to selectively engage the second pinion to the second
shaft, the third pinion to the second shaft or neither the second
pinion nor the third pinion to the second shaft when a neutral
position. When engaged, either the second pinion or the third
pinion rotated in synchronization with the second motor.
[0007] In an aspect of the disclosure, the gear box further
comprises a fourth shaft extending through a first gear and a
second gear and an other pinion. The first gear meshes with the
first pinion. The second gear meshes with the second pinion. The
other pinion meshes with the third pinion and a fourth gear. The
second gear has substantially the same tooth count as the first
gear.
[0008] The differential is mechanically coupled to the fourth gear
and a left axle shaft and a right axle shaft.
[0009] In an aspect of the disclosure, the first shifter and the
second shifter may be asynchronously controlled to such that one of
the first shifter and the second shifter is engaged with a pinion
when the other of the first shifter and the second shifter is in
the neutral position. This control occurs both during acceleration
and deceleration. During deceleration the control is such that one
motor of the first motor and the second motor is coupled to the
fourth gear and maintains a capability of electric regenerative
braking during shifting.
[0010] In an aspect of the disclosure, the motor inverters may
communicate with each other. When one of the first shifter and the
second shifter is controlled to switch an engagement of a pinion
for an associated motor, a corresponding motor inverter to the
switch informs an other motor inverter of the first motor inverter
and the second motor inverter of the switch.
[0011] In another aspect of the disclosure, in response to receipt
of the information of switching, the other motor inverter of the
first motor inverter and the second motor inverter may control a
corresponding motor of the first motor and the second motor to
increase its output from prior to the switch.
[0012] In another aspect of the disclosure, when one of the first
shifter and the second shifter is switched and the one of the first
shifter and the second shifter is in the neutral position, e.g.,
the motor is in neutral. At this time, the corresponding motor
inverter receives a motor speed of the motor not being switched
from the other motor inverter. In response to receipt of the motor
speed, the corresponding motor inverter controls the motor
associated with the one of the first shifter and the second shifter
being switched to match a speed of a gear being switched to based
on a preset ratio determined from a tooth count and a speed of the
motor not being switched.
[0013] In another aspect of the disclosure, each of the first motor
inverter and the second motor inverter comprises at least a voltage
sensor and a current sensor coupled to a respective motor and a
processor and wherein the processor is configured to detect a
failure based on a signal from the at least a voltage sensor and a
current sensor. When a failure is detected in one or more of the
first motor and the second motor, a corresponding shifter of the
first shifter and the second shifter may be controlled to move to a
neutral position for the motor that was detected as a failure.
[0014] In another aspect of the disclosure, when a failure is
detected in one or more of the first motor inverter and the second
motor inverter, a corresponding shifter of the first shifter and
the second shifter is controlled to connect the one or more of the
first motor and the second motor which corresponds to the detected
failed inverter to the neutral.
[0015] In another aspect of the disclosure, the first motor and the
second motor may be positioned a distance from the axle, the
distance being greater than a radius of the axle plus a radius of
respective motor of the first motor and the second motor plus a
preset value.
[0016] In another aspect of the disclosure, the vehicle may be an
electric or a hybrid electric vehicle.
[0017] In another aspect of the disclosure, a hybrid or electric
vehicle is disclosed. The vehicle comprises an energy storage
system, motors, motor inverters, a gear box and a differential. The
energy storage system is configured to supply power to a DC link.
The motors include at least two motors, such as a first motor and a
second motor. The motor inverters include at least two inverters,
such as a first inverter and a second inverter. The first inverter
is coupled to the energy storage system via the DC link and the
first motor. The first motor inverter is configured to receive
power from the DC link and provide AC power to the first motor. The
second inverter is coupled to the energy storage system via the DC
link and the second motor. The second motor inverter is configured
to receive power from the DC link and supply AC power to the second
motor.
[0018] The gear box is mechanically coupled to the motors. The gear
box comprises a first shaft coupled to the first motor and a second
shaft coupled to the second motor. The first shaft and the second
shaft are concentric with a third shaft. The first shaft extends
through a first pinion. The second shaft extends through a second
pinion. The third shaft extends through a third pinion. The second
pinion has substantially the same tooth count as the first pinion.
The third shaft is independent from the first shaft and the second
shaft. The gearbox further has a first shifter for the first motor
and a second shifter for the second motor.
[0019] In an aspect of the disclosure, the first shifter is
configured to selectively engage the first pinion to the first
shaft, the third pinion to the first shaft or neither the first
pinion nor the third pinion to the first shaft when in a neutral
position. When engaged, either the first pinion or the third pinion
rotated in synchronization with the first motor.
[0020] In an aspect of the disclosure, the second shifter is
configured to selectively engage the second pinion to the second
shaft, the third pinion to the second shaft or neither the second
pinion nor the third pinion to the second shaft when a neutral
position. When engaged, either the second pinion or the third
pinion rotated in synchronization with the second motor.
[0021] In an aspect of the disclosure, the gear box further
comprises a fourth shaft extending through a first gear and a
second gear and an other pinion. The first gear meshes with the
first pinion. The second gear meshes with the second pinion. The
other pinion meshes with the third pinion and a fourth gear. The
second gear has substantially the same tooth count as the first
gear.
[0022] The differential is mechanically coupled to the fourth gear
and a left axle shaft and a right axle shaft.
BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 illustrates a diagram of a system in accordance with
aspects of the disclosure;
[0024] FIG. 2 illustrates a diagram of a gear box in accordance
with aspects of the disclosure;
[0025] FIG. 3 illustrates a flowchart for switching gears for a set
of motors in accordance with aspects of the disclosure;
[0026] FIG. 4 illustrates a diagram of an inverter in accordance
with aspects of the disclosure;
[0027] FIG. 5 illustrates a flowchart for responding to a motor
malfunction in accordance with aspects of the disclosure;
[0028] FIG. 6 illustrates a flowchart for responding to inverter
malfunction in accordance with aspects of the disclosure;
[0029] FIG. 7 illustrates a diagram of a system control unit (SCU)
in accordance with aspects of the disclosure;
[0030] FIG. 8 illustrates a diagram of another system in accordance
with aspects of the disclosure;
[0031] FIG. 9 illustrates an example of a shifter position when one
is in hi gear and the other is in low gear; and
[0032] FIG. 10 illustrates an example of a shifter position when
both are in low gear.
DETAILED DESCRIPTION
[0033] The systems described herein may be used in a moving vehicle
with an axle. The vehicle may be a hybrid vehicle or an electric
vehicle. In a case where a vehicle has multiple axles, the systems
described herein may be used for each axle (one per axle). The
moving vehicle may be a bus, a truck, a car and the like having an
axle.
[0034] FIG. 1 depicts a diagram of an example of a system 1 used in
an electric vehicle. The system 1 comprises two motors, motor 1
10.sub.1 and motor 2 10.sub.2 (collectively motors 10). The motors
10 may be off the shelf motors. The motors 10 may be switching
motors. This is a specific example of a motor and other motors may
be used in accordance with aspects of the disclosure. The specific
motor used may be based on the type of vehicle and performance
requirements.
[0035] The motors 10 are connected to the same gear box 25.
Specifically, the output shaft (collectively output shaft 11 and
individually output shaft 1 11.sub.1 and output shaft 2 11.sub.2)
of the motors are connected with the gear box 25. Since the motors
are connected to the same gear box, the motors are cross-coupled.
The motors 10 may share the load, e.g., axle 35 via differential
30, therefore, in a case of a failure, the motors 10 provide
redundancy.
[0036] FIG. 2 depicts an example of a gear box 25 in accordance
with aspects of the disclosure. The gear box 25 comprises a
plurality of gears including pinion gears. In the example, the gear
box 25 has a common high range pinion gear Hp, which was common to
both motors. The gear box also has respective individual gear
systems which are specific to each motor 10.sub.1 and 10.sub.2. The
respective individual gear systems are the same for both motors
10.sub.1 and 10.sub.2. The respective individual gear systems
comprise a low range pinion (collectively pinion LP and
individually pinion L1p and pinion L2p) and a low range gear
(collectively gear Lg and individually gear L1g and gear L2g.) The
tooth count for pinion L1p and pinion L2p are the same. Similarly,
the tooth count for gear L1g and gear L2g are the same. Pinion L1p
and low range gear L1g are used for the motor 1 10.sub.1 and pinion
L2p and low range gear L2g are used for the motor 2 10.sub.2.
[0037] The gear box 25 also comprises a common pinion gear Cp. In
some aspects of the disclosure, the gear box 25 may also comprise a
common gear (Cg) (also referred to as a differential gear). In
other aspects of the disclosure, the differential gear is external
to the gear box 25.
[0038] The gear box 25 further comprises a plurality of shafts. For
example, the gear box 25 comprises Shafts 1-4 200, 205, 210, 215.
Shafts 1-3 200, 205, 210 are concentric. Shaft 1 is connected to
output shaft 11.sub.1 of the first motor 10.sub.1. Shaft 2 is
connected to output shaft 11.sub.2 of the second motor 10.sub.2.
Shaft 3 210 extends between Shaft 1 200 and Shaft 2 205. Shaft 3
210 extends through the high range pinion Hp. Shaft 1 extends
through the low range pinion L1p and Shaft 2 extends through the
low range pinion L2p. Each Shaft 1-4 is supported on ends by
bearings 220.
[0039] Shaft 4 215 extends through the low range gears L1g and L2g
and the common pinion Cp. When Shaft 4 rotates (being driven by one
of the pinions), the low range gears Lg (L1g (when connected to the
shifter S) and common pinion Cp rotate.
[0040] The gear box 25 also comprises shifters (collective shifter
S, individually Shifter S1 and Shifter S2). Shifter S1 is used for
motor 1 10.sub.1 and shifter S2 is used for motor 2 10.sub.2. The
shifters S are configured to shift gear systems between the common
gear system, e.g., high gear, a neutral and the respective
individual gear systems. The shifters S mesh or contact the collar
of the respective gears and couple the same to a respective shaft.
FIG. 9 illustrates an example where shifter S1 is located around
the hi range pinion Hp (high gear) (around the collar) and shifter
S2 is located around the low range pinion L2p (low gear) (around
the collar). FIG. 10 illustrates an example where shifter S1 is
located around the low range pinion L1p (low gear) (around the
collar) and shifter S2 is located around the low range pinion L2p
(low gear) (around the collar).
[0041] When in neutral, the Shaft 4 215 rotates, without being
connected to any of the gears, e.g., free spin. However, when in
either high or low gear, when the Shaft 4 215 rotates (being driven
by the motor(s) 10) and one or more of the gears rotated in
conjunction.
[0042] In an aspect of the disclosure, the shifters S may comprise
a rod, yoke, and dogs, in another aspect may comprise hydraulic or
pneumatic clutches.
[0043] The system 1 also comprises a differential 30. The common
gear Cg is connected to the differential 30 to drive the same, and
thus, the gear box 25 is connected to the differential 30.
[0044] The gear ratios are based on tooth count in the respective
gears. For example, the high range gear ratio is determined based
on the following equation:
Hi range gear ratio=Cg/Hp (1).
[0045] The low range gear ratio is determined based on the
following equation:
Low range gear ratio=(Lg/Lp)*(Cg/Cp) (2).
[0046] Both motors 10 have the same low range gear ratio.
[0047] The tooth count and type of gear system may be based on the
type of vehicle, size, weight and/or performance requirements
and/or type of propulsion motor(s). For example, the tooth count
and gear system may be different for a bus than a car.
Additionally, the tooth count and type of gear system may be
different for a 40 foot bus than a 60 foot bus. Additionally, the
tooth count and type of gears may be different for motors of
different operating speed and/or torque ranges.
[0048] For example, the tooth count for the low range pinion Lp for
a 40 foot bus may be 24, whereas the tooth count for the low range
pinion Lp for a 60 foot bus may be 26. Similarly, the tooth count
for the low range gear Lg may be 64 for the 40 foot bus and 66 for
the 60 foot bus. Thus, the low range gear ratio for the 40 foot bus
may be 6.72 whereas, the low range gear ratio for the 60 foot bus
may be 7.57 to account for vehicle weight differences.
[0049] In an aspect of the disclosure, the tooth count for the high
range may be the same for both the 40 and 60 foot bus. For example,
the high range pinion Hp may have a tooth count of 21; the common
pinion Cp may have a tooth count of 23; and the common gear Cg may
have a tooth count of 58. Thus, the Hi range gear ratio may be 2.76
as both vehicles have the same top speed requirements.
[0050] In an aspect of the disclosure, a 2.5 module gear system may
be used for the low range. In other aspects of the disclosure, a
3.0 module gear system may be used for the low range. In an aspect
of the disclosure, a 6.0 module gear system may be used for the
high range. The type of gear described above is an example for
descriptive purposes only and other systems and tooth counts may be
used.
[0051] Additionally, the gear box 25 depicted in FIG. 2 has two
levels of gears (low gear and high gear), in other aspects of the
disclosure, the gear box 25 may be more than two levels, such as
low, mid and high or 1st-5th gears.
[0052] As described above, the motors 10 are connected to the same
gear box 25 and thus motor 1 10.sub.1 and motor 2 10.sub.2 are also
both connected to the differential 30.
[0053] The differential 30 may be a standard, off the shelf
differential, the structure of which is known and will not be
described in detail.
[0054] The axle half-shaft(s) 35 (also referred to herein as
axle(s) 35) are connected to the differential 30. For example, the
axles 35 are connected to respective gears in the differential
30.
[0055] Planetary wheel reductions 40 are located on the respective
ends of the axle shaft(s) 35. The planetary wheel reductions are
connected with the wheels of the vehicle, respectively. The
planetary wheel reduction 40 reduces rotary speed of the axle
half-shafts 35 to a lower rotary speed more appropriate to the
vehicle and tire size and desired vehicle road speed. For example,
the axle half-shaft 35 for a 40 foot bus may rotate at 2280 RPM.
However, the wheels may only rotate at 570 RPM at a specific speed
of the vehicle, e.g., 65 mph. Therefore, for a 40 foot bus, the
reduction ratio may be 4 to 1. In another example, the axle
half-shaft 35 for a 60 foot bus may rotate at 3680 rpm. Therefore,
for a 60 foot bus, the reduction ratio may be 4.706 to 1.
[0056] In an aspect of the disclosure, the motors 10 are located a
predetermined distance D from the axle 35. The distance both
minimize overhung moment on the axle-housing while still allowing
for easy access to the motors 10 for maintenance and repair which
is an advantage over certain known systems were the motor is much
less accessible located in the wheel hub assembly. In an aspect of
the disclosure, the predetermined distance D is the radius of the
motor plus the radius of the axle shaft tube plus a preset offset
distance which may be determined by an appropriate service
clearance between the two. For example, the predetermined distance
D may be 375 mm. In another aspect of the disclosure, the
predetermined distance D may be 315 mm.
[0057] In another aspect of the disclosure, the predetermined
distance D may be based on the size of the gear system or gear box.
In this aspect, the predetermined distance D may be a sum of the
distance between the output shaft 11 of the motor to Shaft 4 215
and the distance from the Shaft 4 215 to the axle 35. For example,
the distance between the output shaft 11 and Shaft 4 215 may be 132
mm and the distance between Shaft 4 215 and the axle 35 may be 243
mm. The specific examples of distances are provided only for
descriptive purposes and other distance may be used.
[0058] The system 1 also comprises an energy storage system (ESS)
20 and inverters (collectively 15 and individually inverter 1
15.sub.1 and inverter 2 15.sub.2). Inverter 1 15.sub.1 is for the
motor 1 10.sub.1 and inverter 2 15.sub.2 is for motor 2 10.sub.2.
The ESS 20 provides direct current (DC) electric power to a high
voltage DC link which is coupled to the inverters 15. The DC link
is shown in the figures as lines (the three-phase AC power is shown
by dots). The ESS 20 in one example includes lithium ion batteries.
In an aspect of the disclosure, the nominal voltage of the ESS 20
is 500V-750V. In other aspects of the disclosure, the DC-Link
voltage may be 250V-450V.
[0059] The ESS 20 may also alternatively include ultra-capacitors,
lead-acid batteries, and other energy storage mediums. The
ultra-capacitor may include an electric double-layer capacitor
(EDLC), also known as a, supercapacitor, supercondenser, or an
electrochemical double layer capacitor, which has an
electrochemical capacitor with relatively high energy density.
[0060] The inverters 15 receive DC power from the ESS 20 via the DC
link and provide a three-phase AC power to the motors 10,
respectively. The three phase AC power is shown in the figures as
dots connecting the inverter and motor.
[0061] The term inverter used herein not only means circuitry for
transforming DC into AC or vice versa, but also include control
circuitry and programs for functions, including but not limited to,
frequency determination and duty cycle calculations and determining
whether a malfunction is occurring in a motor(s) 10.
[0062] In an aspect of the disclosure, the inverters 15 may also
control the shifters S to shift between gears. The inverter 15 also
includes sensors. For example, as shown in FIG. 4, inverter 15
comprises a voltage sensor 400 on the DC Link and voltage sensors
420 on each phase of the three phase AC voltage current sensors 405
(two current sensors, respectively on two of the three phases). In
an aspect of the disclosure, a voltage sensor detects a voltage of
the ESS 20. Similarly, the current sensors 405 detect the current
of two of the three-phases output from the inverter 15.
[0063] The inverters 15 also comprise a processor 410. The
processor 410 may control the switching of the gears and determine
whether a malfunction is occurring in the motor (or has occurred)
based on information from the voltage sensors 400, the current
sensors 405 and voltage sensors 420. Additionally, the processor
410 (of one inverter) may communicate with the other inverter via a
communication interface 415 (the processor of the other inverter).
In an aspect of the disclosure, the inverters 15 may communicate
with each other over a control area network (CAN), as shown in the
figures as thin communication lines, e.g., 1M bit/sec CAN. The
inverter also includes the conversion electronics 425.
[0064] The system 1 further comprises a system control unit (SCU)
45. The SCU 45 communicates with various components of the vehicle
over the CAN, shown in the figures as thin communication lines. For
example, the SCU 45 communicates with inverter 1 15.sub.1 and
inverter 2 15.sub.2, and the ESS 20.
[0065] The SCU 45 comprises a processor 700, a memory 705 and a
communication interface 710 (for CAN). Certain functionality of the
processor will be described in detail later.
[0066] The processor (both 410 and 700) may be a microcontroller or
microprocessor or any other processing hardware such as a CPU or
GPU. The memory may be separate from the processor (as or
integrated in the same). For example, the microcontroller or
microprocessor includes at least one data storage device, such as,
but not limited to, RAM, ROM and persistent storage. In an aspect
of the disclosure, the processor may be configured to execute one
or more programs stored in a computer readable storage device. The
computer readable storage device can be RAM, persistent storage or
removable storage. A storage device is any piece of hardware that
is capable of storing information, such as, for example without
limitation, data, programs, instructions, program code, and/or
other suitable information, either on a temporary basis and/or a
permanent basis.
[0067] The SCU 45 in conjunction with the inverters 15 control the
amount of power supplied to the motors, when to switch gears and
the switching of the gears.
[0068] In an aspect of the disclosure, the processor 700 in the SCU
45 determines when to switch the gears, e.g., the appropriate
switching point. In an aspect of the disclosure, the determination
may be based on speed of the motor. In other aspects of the
disclosure, the determination may be based on a torque of the
motor. Alternatively, in other aspects of the disclosure, both the
speed and the torque of the motor may be used.
[0069] Since speed and/or torque may be used to determine when to
switch, switching may also be determined based on the type of motor
used. For example, different motors have different
power/speed/torque curves.
[0070] Additionally, the type of vehicle may also be used to
determine when to switch gears. For example, the optimal switching
point is different for a 40 foot bus verses a 60 foot bus.
[0071] In an aspect of the disclosure, the switching point(s) may
be stored in memory 705. For example, a switching point for going
from low to high gear may be stored in advance. Similarly, a
switching point for going from high to low gear may be stored in
advance. The two switching points, e.g., low to high gear and high
to low gear may be different. In other aspects of the disclosure,
the two switching points are the same. For example, for a 40 foot
bus, the optimal shift point may be 7000 rpm (at approximately 30
mph). The optical shift point for a 60 foot bus may be 7500 rpm (at
approximately 24 mph).
[0072] In an aspect of the disclosure, the determination of when to
switch gears is also based on the requested propulsion by the
operator of the vehicle. The requested propulsion may be a speed
command or a torque command or a power command. The SCU 45 using
its control laws determines the required output for the motors
based on the inputted propulsion request and the current operating
conditions.
[0073] For example, when a higher torque is needed, the low gear
may be used. Additionally, when a higher speed is needed (with a
low torque), the high gear may be used.
[0074] During normal driving (with no malfunction) and no
switching, both shifters are either connected with the hi range
pinion Hp (high gear) or the respective individual gears L1p and
L2p (low gear). Both motors 10 share the load. In an aspect of the
disclosure, the SCU 45 causes the motors 10 to balance the load,
e.g., share the load 50/50. In other aspects of the disclosure,
equal load balancing is not required.
[0075] In accordance with aspects of the disclosure, the motors 10
switch gears asynchronously, such that one motor remains connected
to the differential 30 and axle half-shafts 35 when the other is
switching gears (shifters not in neutral position at the same
time).
[0076] FIG. 3 illustrates a flow chart of switching gears in
accordance with aspects of the disclosure. The switching described
herein may occur during acceleration and deceleration.
[0077] At S1, the processor 700 determines whether switching is
needed. In accordance with aspects of the disclosure, the processor
700 receives a current operating speed from the inverters 15
(processor 410). The current operating speed may be determined
without sensors or by using a speed sensor (not shown). The speed
sensor may be a resolver. In an aspect of the disclosure, the
processor 700 also receives from the inverters 15 the current
position of the shifters S, e.g., which pinion, respectively, for
each motor. The processor 700 also receives a propulsion request
from the operator and determines the required propulsion, e.g.
torque and speed of the motors. The processor 700 may compare the
determined speed needed from the motors with the current operating
speed. If the determined speed needed for the motors is higher than
the current operating speed, the processor 700 retrieves the
switching point for low to high gear from memory 705 when the
current position of the shifters S is connected to the respective
low range pinions L2p (low gear). Subsequently, the processor 700
compares the determined speed needed from the motors with the
switching point for low to high gear, e.g., 7000 rpm for 40 foot
bus or 7500 rpm for 60 foot bus. If the determined speed needed is
higher than the switching point, the processor 700 determines that
switching is needed ("Y" at S3) (switching from low to high gear).
On the other hand, if the determined speed needed is lower than or
equal to the switching point, the processor 700 determines that
switching is not needed ("N" at S3)
[0078] When the current position of the shifters S is the hi range
pinion Hp and the determined speed needed is higher than the
current speed, since the shifters S are already connected to the
high gear, no switching is needed ("N" at S3).
[0079] If the determined speed needed for the motors is lower than
the current operating speed, the processor 700 retrieves the
switching point for high to low gear from memory 705 when the
current position of the shifters S is connected to the hi range
pinion Hp (high gear).
[0080] Subsequently, the processor 700 compares the determined
speed needed from the motors with the switching point for high to
low gear. If the determined speed needed is lower than the
switching point, the processor 700 determines that switching is
needed ("Y" at S3) (switching from high to low gear). On the other
hand, if the determined speed needed is higher than the switching
point, the processor 700 determines that switching is not needed
("N" at S3)
[0081] When the current position of the shifters S is the
respective individual gears L1p and L2p (low gear) and the
determined speed needed is lower than the current speed, since the
shifters S are already connected to the low gear, no switching is
needed ("N" at S3).
[0082] While the above switching determination was described with
respect to the speed of the motor and the switching point(s) are
speed(s), the determination may be based on required torque and the
switching point(s) may be a preset torque.
[0083] When the processor 700 determines that switching of the
gears is needed ("Y" at S3), the processor 700 issues an
instruction to the processors 410 in the inverters 15 to begin the
switching process (either low to high gear or high to low
gear).
[0084] At S5, one of the motors is selected to switch first, since
both motors 10 are not switched at the same time. In an aspect of
the disclosure, either motor 1 10.sub.1 or motor 2 10.sub.2 is set
as a default to switch first. For purposes of the description,
motor 1 10.sub.1 is set as the default to switch first.
[0085] Prior to the switch, the requested torque is reduced also at
S5. This is to avoid the motor 10 overspeeding if the torque were
still present. Once the torque is reduced, the processor 410 (in
inverter 1 15.sub.1) causes the shifter S1 to shift to a neutral
position (not connected to either low range pinion L1p or high
range pinion Hp). For example, the processor 410 may use a
mechanical actuator (not shown) to move the shifter S1.
[0086] At S7, the processor 410 (in inverter 1 15.sub.1) transmits
an indication to the processor 410 (in inverter 2 15.sub.2) that
the switch has begun. The transmission is via CAN and using the
respective communication interfaces 415.
[0087] Upon receipt of the indication, the processor 410 (in
inverter 2 15.sub.2) boosts the output of motor 2 10.sub.2 at S9.
The amount of the boost is to cover the transient change (e.g.,
amount lost when motor 1 is switched). As described above, when
both motors 10 are connected to a gear (driving the gears), the
motors share the load, e.g., 50/50. However, when a shifter is
moved to switch gears, the entire load is supported by the other
motor; up to the lesser of the total power demand or the maximum
transient power capacity of the motor. In this case, shifter S1 is
switched to neutral and thus the corresponding motor is not driving
the gears. Therefore, motor 2 10.sub.2, which is still driving the
gears, maintains the output to be the same as if both motors 10
were driving. This boost is only temporary and to the extent that
the motor 2 10.sub.2 is capable of meeting the demand without
exceeding its limit. Therefore, the amount of the temporary boost
is based on the power being delivered prior to the switch. In an
aspect of the disclosure, the temporary boost may be double the
pre-switch output. The temporary boost allows the operator of the
vehicle not to feel the change as the performance of the vehicle
remains the same, e.g., no power or torque interruption. In an
aspect of the disclosure, the boost amount may also be based on the
current propulsion demand from the operator (if changed).
[0088] Once the power is boosted, the processor 410 (in inverter 2
15.sub.2) reports to the processor 410 (in inverter 1 15.sub.1) the
speed of motor 2 10.sub.2. The current operating speed of motor 2
10.sub.2 may be determined in a similar manner as described above.
The processor 410 (in inverter 2 15.sub.2) transmits the speed via
CAN using the communication interface 415.
[0089] At S10, the processor 410 (in inverter 1 15.sub.1) receives
the speed of motor 2 10.sub.2, and causes the speed of gear which
is being switch to, to match the speed of the other motor. The gear
ratios, e.g., High/Low or Low/High and low range gear ratio and
high range gear ratios are known. In an aspect of the disclosure,
these ratios are stored in memory in the inverters 15. Thus, when
the processor 410 (in inverter 1 15.sub.1) receives the speed of
motor 2 10.sub.2, the processor 410 retrieves the appropriate ratio
(depending on the current gear connections) and determines the
needed speed for the gear which is being switch to and thus, the
motor 1 10.sub.1 speed needed to match.
[0090] Example, if motor 1 10.sub.1 is being switched (shifter S1
is moved) from lo-to-hi and motor 2 10.sub.2 remains driving the
gears, when motor 2 10.sub.2 is reporting 7000 rpm, the hi-range
pinion (Hp) speed will be: 7000*(L2p/L2g)*(Cp/Hp), and motor 1
10.sub.1 will synchronize its speed to match Hp speed based on
updated speed data from Motor 2 10.sub.2.
[0091] After the speed is determined, the inverter 1 15.sub.1
supplies the power required to the motor, e.g., motor 1 10.sub.1,
and the processor 410 (in inverter 1 15.sub.1) completes the switch
at S11 by actuating the shifter S1 (either connect to Low range
pinion L1p or high range pinion Hp).
[0092] When the switching is complete, the processor 410 (in
inverter 1 15.sub.1) notifies the processor 410 (in inverter 2
15.sub.2) that the switch is completed at S13. The other motor is
then switched to neutral at S15 (after the torque is reduced).
S7-S13 are repeated for the other motor, e.g., motor 2 10.sub.2. In
other aspects of the disclosure, the switching of the second motor
may not be performed, depending on a current propulsion
request.
[0093] Once both of the motors 10 are switched, both are either
connected to the low range pinion Lp (L1p or L2p) or the high range
pinion Hp and share the load equally again. The temporary boost of
the output is reduced to the pre-switching output.
[0094] By having the motors 10 switch (shifters S1 and S2) operated
independently and at different times, e.g., asynchronously, the
time for shifting may be longer than if both motors are shifted at
the same time, but switching at the same time means that neither
motor 10 is driving the load and thus the load would not be
supplied with power during switching. In this situation the
operator of the vehicle would notice performance drop, e.g., power
reduction and speed reduction. The longer switching time
advantageously provides less wear on the shifters S and other
mechanical components involved in the switching (such as
actuators).
[0095] Additionally, in accordance with aspects of the disclosure,
due to the redundant configuration, e.g., cross coupling of the
motors 10, even when one of the motors fails, the vehicle may still
be driven. FIG. 5 illustrates a flowchart for responding to a motor
malfunction in accordance with aspects of the disclosure.
[0096] Each inverter 15 respectively monitors the functioning of
its corresponding motor. Inverter 1 15.sub.1 monitors motor 1
10.sub.1 and inverter 2 15.sub.2 monitors motor 2 10.sub.2. Based
on this monitoring, the inverter 15 may detect a malfunction and
respond accordingly.
[0097] In an aspect of the disclosure, a malfunction may be
detected based on current and/or voltage readings measured by
sensors 400, 405, 420 or when a DC and/or AC ground fault is
detected. The ground fault is detected relative to chassis. For
example, at S500, the processor 410 (in each inverter 15) receives
signals from the sensors 400, 405, 420. A significant change from
expected values may indicate a fault or malfunction. For example,
in a case where a short occurs in the motor, current would spike
and would be sensed by the current sensors 405. A significant
change may be determined by a percentage deviation from the
expected values. For example, when a sensed value exceeds the
expected value by a preset percentage, the change is deemed
"significant". For example, the percentage may be 50% or more. In
other aspects, the percentage may be 100% or more. In other
aspects, the percentage may be 20% or more.
[0098] In other aspects, instead of a percentage, a preset value
may be used. By monitoring the current and the voltage, changes in
the same may be quickly discovered. If the voltage or current
changed more than a preset amount (from a set value), the processor
410 determines a malfunction has occurred in the motor ("Y" at
S502). In other aspects, the processor 410 also determines if a DC
and/or AC ground fault has occurred and determines that a
malfunction has occurred when either a DC or an AC ground
fault.
[0099] When one of the processors 410 (in an inverter) determines
that a malfunction occurs ("Y" at S502) (other than a DC ground
fault), the corresponding motor is shifted into neutral at S504,
whereby the motor cannot drive the gears. The processor 410 moves
the shifter S using an actuator from being connected to a pinion to
a position detached from the same. Additionally, the inverter stops
supplying power to the motor. For example, if motor 1 10.sub.1 was
connected to the low range pinion L1p (and motor 1 is detected to
be malfunctioning), the processor 410 (in inverter 15.sub.1) causes
the shifter S1 to move to disconnect the low range pinion L1. When
a DC ground fault is detected, if the vehicle is a hybrid electric
vehicle, the energy storage system 20 (battery) is disconnected,
however, the motor remains connected powered by the prime mover,
e.g., engine 800.
[0100] When the motor, e.g., motor 1 10.sub.1, is disconnected and
powered down, the processor 410 (e.g., in inverter 15.sub.1 using
the above example) transmits a notification to the processor 410
(in the other inverter, e.g., in the above example, inverter
15.sub.2) indicating the switch at S506.
[0101] In response to receiving the notification, the processor 410
(in inverter 15.sub.2) causes motor 2 10.sub.2 (the working motor)
to increase its output (to the extent that it is capable) in order
to maintain the output to the load (e.g., axle 35 via the
differential 30) at pre-shifted levels. Once again, as noted above,
this assumes that the working motor can handle the additional
load.
[0102] In an aspect of the disclosure, when a motor is shifted to
neutral, one of the inverters (15.sub.1 and/or 15.sub.2) may inform
the SCU 45. In an aspect of the disclosure, upon receipt of the
notification from one of the inverters (15.sub.1 and/or 15.sub.2),
the SCU 45 may issue a system level warning to the operator of the
vehicle, such as a warning to be displayed on a dashboard of the
vehicle (not shown). By providing the warning, the operator of the
vehicle may drive the vehicle to an area for maintenance, such as a
bus depot or a gas station. Additionally, by providing the warning,
the operator of the vehicle may alter the propulsion request to
avoid overtaxing the working motor.
[0103] In another aspect of the disclosure, upon receipt of the
notification, the SCU 45 may alter the propulsion command to the
inverter of the working motor (e.g., inverter 2 15.sub.2 using the
above example). Thus, the vehicle may include a reduced power mode
in a case where one of the motors malfunctions.
[0104] Similarly, in a case where an inverter malfunctions, a
corresponding motor may also be disconnected from the load, e.g.,
axle 35 via the differential 30.
[0105] In other aspects of the disclosure, instead of the processor
415 in the inverter determining whether a malfunction exists, the
processor 700 in the SCU 45 makes the determination.
[0106] FIG. 6 illustrates a flowchart for responding to an inverter
malfunction in accordance with aspects of the disclosure.
[0107] At S600, the processor 415 in the inverter monitors whether
the inverter 15 is functioning properly (self-monitoring). In one
example, the processor 415 may use the voltage sensors 400/420 or
current sensors 405 to determine whether there is a failure at the
inverter level. A failure at the inverter level may be a DC link
fault or any type of ground error. Other errors may be possible
such as a bad processor 415. When a fault occurs in the inverter
15, the processor 415 (in the inverter reports the fault) to the
processor 700 in the SCU 45 at S602.
[0108] Upon receive of the fault condition, the processor 700
issues a command to the inverter that malfunctioned via CAN to
isolate the corresponding motor, e.g., switch the motor to neutral,
at S604. In other aspects of the disclosure, the inverter 15 may
also isolate the corresponding motor without waiting for an
instruction from the SCU 45 (omit S604).
[0109] In response to the receipt of the command, S504-S506 are
performed by the inverter that received the command. Therefore, in
accordance with aspects of the disclosure, even if there is a
malfunction in either an inverter or motor, the vehicle may be
still driven, using the other inverter/motor combination. Similar
to above, when an inverter malfunctions, the SCU 45 may issue a
system level warning to the operation for display on the
dashboard.
[0110] In an aspect of the disclosure, the processor 700 in the SCU
45 may interpret a failure to receive a periodic message from the
inverter 15 as a failure in the inverter 15 and issue the command
when a message is not received within a preset period of time. For
example
[0111] While it has been described herein that a processor in the
inverters controls the shifters S, in other aspects of the
disclosure, the SCU 45 (processor 700) actuates the shifters S and
controls the same.
[0112] FIG. 8 depicts a block diagram of an example of a system 1A
used in a hybrid electric vehicle. The system 1A is similar to
system 1 except system 1A also comprises an engine 800, a generator
805 and a generator inverter 810. The engine 800 (e.g., a prime
mover) may be an engine that uses fuel such as gasoline, a diesel
or compressed natural gas (CNG) engine (collectively referred to
herein as "fuel"). The engine 800 comprises a crankshaft (not shown
in the figures). The crankshaft rotates. For example, typical
compression ignition engine comprises a plurality of cylinders
(e.g., combustion chambers). The combustion chamber is where fuel
is combusted. A piston moves within the chamber, e.g.,
reciprocating motion. The piston transmits a thrust force generated
to the crankshaft through one or more connecting rods. The
crankshaft converts the reciprocating motion into rotary motion.
Each combustion chamber may have an injector. The injector injects
fuel into the chamber. Each combustion chamber further has an inlet
valve(s) and an exhaust valve(s). Exhaust from the combustion
chamber is removed through the exhaust valve(s).
[0113] The generator 805 may be an integrated-starter generator
("ISG"). The generator 805 in this example is mechanically
connected to the engine 800. The generator may be connected via a
belt/pulley system which is connected to a movable shaft of the
generator (also not shown in the figures) and to the crankshaft or
another shaft. In other aspects of the disclosure, the generator
805 may be connected to the engine 800 in other ways, such as a
power take off (PTO) shaft or directly connected to the prime
mover.
[0114] The generator 805 may be a permanent magnet generator. Other
generators may be used. When coupled to the engine 800 (referred to
herein as the genset), the generator provides three-phase AC
electrical power. The generator 805 may provide a variable
frequency AC electrical power. The generator 805 in one example is
a high voltage generator.
[0115] The generator inverter 810 is electrically connected to the
generator 805. The generator inverter 810 receives the three phase
AC electric power from the generator 805 and provides a high
voltage (DC). The high voltage (DC), e.g., DC link, is coupled to
an ESS 20 and inverters 15. The other structures in FIG. 8 and
their functionality are the same as in FIG. 1 and described above
and will not be described again in detail.
[0116] In other aspects of the disclosure, the hybrid electric
vehicle may comprise a fuel cell instead of an engine.
[0117] As used herein, the term "processor" may include a single
core processor, a multi-core processor, multiple processors located
in a single device, or multiple processors in wired or wireless
communication with each other and distributed over a network of
devices, the Internet, or the cloud. Accordingly, as used herein,
functions, features or instructions performed or configured to be
performed by a "processor", may include the performance of the
functions, features or instructions by a single core processor, may
include performance of the functions, features or instructions
collectively or collaboratively by multiple cores of a multi-core
processor, or may include performance of the functions, features or
instructions collectively or collaboratively by multiple
processors, where each processor or core is not required to perform
every function, feature or instruction individually.
[0118] Various aspects of the present disclosure may be embodied as
a program, software, or computer instructions embodied or stored in
a computer or machine usable or readable medium, or a group of
media which causes the computer or machine to perform the steps of
the method when executed on the computer, processor, and/or
machine. A program storage device readable by a machine, e.g., a
computer readable medium, tangibly embodying a program of
instructions executable by the machine to perform various
functionalities and methods described in the present disclosure is
also provided, e.g., a computer program product.
[0119] The computer readable medium could be a computer readable
storage device or a computer readable signal medium. A computer
readable storage device, may be, for example, a magnetic, optical,
electronic, electromagnetic, infrared, or semiconductor system,
apparatus, or device, or any suitable combination of the foregoing;
however, the computer readable storage device is not limited to
these examples except a computer readable storage device excludes
computer readable signal medium. Additional examples of the
computer readable storage device can include: a portable computer
diskette, a hard disk, a magnetic storage device, a portable
compact disc read-only memory (CD-ROM), a random access memory
(RAM), a read-only memory (ROM), an erasable programmable read-only
memory (EPROM or Flash memory), an optical storage device, or any
appropriate combination of the foregoing; however, the computer
readable storage device is also not limited to these examples. Any
tangible medium that can contain, or store, a program for use by or
in connection with an instruction execution system, apparatus, or
device could be a computer readable storage device.
[0120] A computer readable signal medium may include a propagated
data signal with computer readable program code embodied therein,
such as, but not limited to, in baseband or as part of a carrier
wave. A propagated signal may take any of a plurality of forms,
including, but not limited to, electro-magnetic, optical, or any
suitable combination thereof. A computer readable signal medium may
be any computer readable medium (exclusive of computer readable
storage device) that can communicate, propagate, or transport a
program for use by or in connection with a system, apparatus, or
device. Program code embodied on a computer readable signal medium
may be transmitted using any appropriate medium, including but not
limited to wireless, wired, optical fiber cable, RF, etc., or any
suitable combination of the foregoing.
[0121] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting the
scope of the disclosure and is not intended to be exhaustive. Many
modifications and variations will be apparent to those of ordinary
skill in the art without departing from the scope and spirit of the
disclosure.
* * * * *