Title of Invention

A TRANSMISSION CONTROL SYSTEM AND A METHOD FOR REGULATING OPERATION OF AN AUTOMATIC TRANSMISSION OF A VEHICLE

Abstract A transmission control system for regulating operation of an automatic transmission of a vehicle includes a first module that provides a predetermined shift schedule including upshift and downshift lines and a second module that offsets each of the upshift and downshift lines by an offset amount to provide modified upshift and downshift lines when a deceleration of the vehicle exceeds a threshold deceleration. A third module regulates operation of the automatic transmission based on the modified upshift and downshift lines.
Full Text GP-308363-PTT-DLT
Attorney Docket No. 8540P-000431
DECELERATION DEPENDENT SHIFT CONTROL
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/815,147, filed on June 20, 2006. The disclosure of the above
application is incorporated herein by reference.
FIELD
[0002] The present disclosure relates to a powertrain having an
automatic transmission driven by an internal combustion engine through a torque
converter, and more particularly to a deceleration dependent shift control for an
automatic transmission.
BACKGROUND
[0003] The statements in this section merely provide background
information related to the present disclosure and may not constitute prior art.
[0004] Vehicle powertrains typically include a prime mover, such as an
internal combustions engine, that drives a transmission through a coupling
device. In some cases, the transmission includes an automatic transmission that
is driven by the prime mover through a torque converter. The transmission
multiplies the engine drive torque by a desired gear ratio and transfers the
multiplied drive torque to a driveline to propel the vehicle.
[0005] A control module regulates operation of the transmission based
upon vehicle operating parameters including, but not limited to, vehicle speed
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and throttle position. More specifically, the control module includes
predetermined shift lines that are used to command upshift and downshifts.
[0006] In some instances, the vehicle is rapidly decelerated, for
example, to avoid a collision or to otherwise come to a rapid stop. As the vehicle
decelerates, several events can simultaneously occur including, but not limited
to, suspension movement, axle wind-up and a transmission downshift. Under
certain conditions, a transmission downshift can result in undesired driveline
disturbances in the form of noise (e.g., an audible clunk) and/or driveline
oscillations.
SUMMARY
[0007] Accordingly, the present invention provides a transmission
control system for regulating operation of an automatic transmission of a vehicle.
The transmission control system includes a first module that provides a
predetermined shift schedule including upshift and downshift lines and a second
module that offsets each of the upshift and downshift lines by an offset amount to
provide modified upshift and downshift lines when a deceleration of the vehicle
exceeds a threshold deceleration. A third module regulates operation of the
automatic transmission based on the modified upshift and downshift lines.
[0008] In one feature, the transmission control system further includes
a fourth module that determines the offset amount based on at least one of a
current gear ratio of the automatic transmission and the deceleration.
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[0009] In another feature, the offset amount is a fixed, predetermined
amount.
[0010] In another feature, the second module stores a base downshift
line vehicle speed, and sets the offset amount to zero when a current vehicle
speed falls below the base downshift line vehicle speed.
[0011] In another feature, the second module initiates a timer upon
executing the step of offsetting, and sets the offset amount to zero when the
timer achieves a threshold time.
[0012] In still another feature, the second module sets the offset
amount to zero when a throttle position exceeds a threshold throttle position.
[0013] In yet other features, the second module monitors a vehicle
speed, and decays the offset amount towards zero when the vehicle speed
accelerates back through the upshift lines. The second module decays the offset
amount based on a decay rate. The decay rate is a predetermined, fixed value.
Alternatively, the decay rate is determined based on an acceleration of the
vehicle.
[0014] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the description and
specific examples are intended for purposes of illustration only and are not
intended to limit the scope of the present disclosure.
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DRAWINGS
[0015] The drawings described herein are for illustration purposes only
and are not intended to limit the scope of the present disclosure in any way.
[0016] Figure 1 is a functional block diagram of an exemplary vehicle
powertrain that is regulated based on the deceleration dependent shift control of
the present invention;
[0017] Figure 2 is a graph illustrating exemplary shift lines for an
exemplary automatic transmission;
[0018] Figure 3-5 are graphs illustrating the exemplary shift lines of
Figure 2 including exemplary offset shift lines in accordance with the deceleration
dependent shift control of the present invention, and exemplary vehicles
maneuvers executed during an offset mode;
[0019] Figure 6 is a flowchart illustrating exemplary steps executed by
the overspeed protection control of the present invention; and
[0020] Figure 7 is a functional block diagram of exemplary modules
that execute the overspeed protection control of the present invention.
DETAILED DESCRIPTION
[0021] The following description of the preferred embodiment is merely
exemplary in nature and is in no way intended to limit the invention, its
application, or uses. For purposes of clarity, the same reference numbers will be
used in the drawings to identify similar elements. As used herein, the term
module refers to an application specific integrated circuit (ASIC), an electronic
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circuit, a processor (shared, dedicated, or group) and memory that execute one
or more software or firmware programs, a combinational logic circuit, or other
suitable components that provide the described functionality.
[0022] Referring now to Figure 1, an exemplary powertrain 10 is
illustrated and includes an engine 12 that drives a transmission 14 through a
torque converter 16. More specifically, air is drawn into an intake manifold 18 of
the engine 12 through a throttle 20. The air is mixed with fuel and the air/fuel
mixture is combusted within cylinders 22 to reciprocally drive pistons (not shown)
within the cylinders 22. The pistons rotatably drive a crankshaft (not shown) to
provide drive torque. Exhaust generated by the combustion process is
exhausted from the engine through an exhaust manifold 26. Although 4 cylinders
are illustrated, it is appreciated that the present invention can be implemented in
vehicles having any number of cylinders.
[0023] The drive torque is transferred through the torque converter 16
to drive the transmission 14. The transmission 14 multiplies the drive torque by a
desired gear ratio to provide a modified drive torque. The modified drive torque
is transferred to a vehicle driveline (not shown) by a transmission output shaft 28.
The transmission 14 can includes an automatic transmission that is automatically
shifted based on a vehicle speed (VVEH) and a throttle position, as discussed in
further detail below.
[0024] A control module 30 regulates operation of the powertrain based
on vehicle operating parameters. More specifically, the control module 30
regulates a throttle opening or throttle position (TPS) corresponding to an
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effective throttle area (AEFF) via a throttle actuator 32. A throttle position sensor
34 generates a throttle position signal based on the angular position of the
throttle 20. The control module 30 regulates operation of the transmission 14
based on vehicle operating parameters. More specifically, a crankshaft position
sensor 36 generates a crankshaft position signal, which is used to determine an
actual engine speed (RPMENG)
[0025] Referring now to Figure 2, the control module 30 adjusts a gear
ratio of the transmission 14 based on the throttle position (i.e., TPS) and VVEH-
More specifically, the control module 30 includes a plurality of pre-programmed
upshift and downshift lines based on VVEH and TPS, which is measured as a
percentage of throttle opening. When the TPS and/or VVEH cross one of the shift
lines, the control module 30 commands a corresponding shift. In the exemplary
graph of Figure 2, upshift and downshift lines are provided for an exemplary 4-
speed automatic transmission. The exemplary downshift lines include 2-1,3-
2 and 4-3 downshift lines. The exemplary upshift lines include 1 - 2, 2 - 3 and
3-4 upshift lines. The lines also include torque converter clutch (TCC) apply
and release lines. For example, if the VVEH is 20 kilometers per hour (kph) and
the TPS is 25%, the automatic transmission is in 2nd gear. If VVEH decreases
past the 2 - 1 downshift line, while the %Throttle decreases or remains constant,
a downshift from 2nd gear to 1st gear is commanded. Similarly, if VVEH increase
past the 2-3 upshift line, an upshift from 2nd gear to 3rd gear is commanded.
[0026] Referring now to Figure 3, the deceleration dependent shift
control of the present invention temporarily offsets the shift lines based on a
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deceleration of the vehicle (i.e., VVEH) More specifically, the acceleration of the
vehicle (aVEH) is determined based on the transmission output shaft signal
(TOSS) and is continuously monitored. If aVEH is negative, the vehicle is deemed
to be decelerating. Furthermore, if aVEH is less than a threshold acceleration
(a-THR) (i.e., is more negative than aTHR), the deceleration dependent shift control
enters an offset mode and offsets the downshift and upshift lines (see phantom
lines). For example, at point A of Figure 3, VVEH is approximately 32 kph and the
transmission is in 4th gear. The vehicle is rapidly decelerated towards point B. In
response to the rapid deceleration, the shift lines are offset. It should be noted
that although only a single offset downshift line is illustrated, it is anticipated that
all of the upshift and downshift lines are offset.
[0027] The offset amount can be a predetermined, fixed value (e.g., 4
kph) or can be determined based on aVEH and/or the current gear. For example,
if the deceleration is very rapid, the offset is greater than if the deceleration is
slower. Alternatively or additionally, the offset can be based on the current gear
ratio. For example, the offset is greater if the vehicle is decelerating and the
transmission is in a higher gear than if the transmission is in a lower gear.
[0028] Upon entering the offset mode, the deceleration shift control
stores the original or base downshift line (e.g., 2-1) and an offset timer tOFFSET is
initiated. The offset mode can be exited upon tOFFSET achieving a threshold time
(tTHR) (e.g., 5 seconds), upon TPS exceeding a TPS threshold (TPSTHR) or upon
VVEH falling below the base downshift line (e.g., the original 2 - 1 downshift line).
For example, as VVEH moves towards point B in Figure 3, and crosses the base 2
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- 1 downshift line, the offset mode is exited and all of the offsets are set equal to
zero (i.e., all of the upshift and downshift lines go back to normal). With
particular reference to Figure 4, the offset mode is exited upon TPS exceeding
TPSTHR, even though the base 2 - 1 downshift line is not crossed.
[0029] Referring now to Figure 5, the offset can decay to zero over
time if there is a sudden reversal in aVEH and VVEH increases. In the exemplary
maneuver illustrated in Figure 5, aVEH is sufficient to enter the offset mode,
however, after VVEH crosses the offset 2-1 downshift line and downshifts to 1st
gear, VVEH suddenly increases. As VVEH moves towards the offset upshift lines,
the offset value decays. In other words, as VVEH moves towards the offset upshift
lines, the offset value decays so that the offset upshift lines are effectively
moving toward VVEH. For example, an upshift from 1st to 2nd gear is commanded
at the fully offset 1-2 upshift line (e.g., offset by 4 kph). An upshift from 2nd to
3rd gear is commanded at the less than fully offset 2-3 upshift line (e.g., the
offset has decayed to less than 4 kph). The offset continues to decay at a
predetermined decay rate until the offset is 0 kph. It is anticipated that the decay
rate can be a predetermined fixed amount or can be determined based on aVEH
as VVEH accelerates back through the upshift lines.
[0030] Referring now to Figure 6, exemplary steps executed by the
deceleration dependent shift control will be described in detail. In step 600,
control determines whether aVER is less than an acceleration threshold (aTHR)- If
aVEH is less than aTHR, the vehicle is sufficiently decelerating to enter the offset
mode, and control continues in step 602. If aVEH is not less than aTHR, the vehicle
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is not sufficiently decelerating to enter the offset mode, and control loops back.
In step 602, control enters the offset mode and offsets the upshift and downshift
lines. As discussed in detail above, the shift lines can be offset by a fixed
amount, or the offset amount can be determined based on the current gear ratio
and/or aVEH Control initiates tOFFSET in step 604.
[0031] In step 606, control determines whether VVEH has crossed the
original or base 2-1 downshift line (VBASE2-1) If VVEH has crossed VBASE2-1,
control continues in step 608. If VVEH has not crossed VBASE2-1, control
determines whether TPS is greater than TPSTHR in step 610. If TPS is greater
than TPSTHR, control continues in step 608. If TPS is not greater than TPSTHR,
control determines whether tOFFSET is greater than tTHR in step 612. If tOFFSET is
greater than tTHR, control continues in step 608. If tOFFSET is not greater than tTHR,
control continues in step 614. In step 608, control exits the offset mode by
setting the offsets to zero, and control ends.
[0032] In step 614, control determines whether VVEH is accelerating
back through the upshift lines (see Figure 5). If VVEH is not accelerating back
through the upshift lines, control increments tOFFSET in step 616 and loops back to
step 604. If VVEH is accelerating back through the upshift lines, control exits the
offset mode by decaying the offsets to zero at a predetermined decay rate, and
control ends. As discussed above, the decay rate and be a fixed amount or can
be determined based on aVEH as the vehicle accelerates.
[0033] Referring now to Figure 7, exemplary modules that execute the
deceleration dependent shift control will be described in detail. The exemplary
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modules include a shift line schedule module 700, an offset module 702, an
offset amount module 704 and a transmission control module 706. The shift line
schedule module 700 includes the predetermined or normal shift lines. The
offset module 702 offsets the shift lines based on inputs from the various
modules and provides the offset shift line information to the transmission control
module 706, which regulates operation of the transmission. The offset amount
module 704 determines the offset value based on aVEH and the current gear,
which is provided by the transmission control module 706.
[0034] The deceleration dependent shift control of the present
invention inhibits driveline disturbances during rapid vehicle deceleration, by
executing transmission downshifts earlier in the deceleration. In this manner, the
deceleration event does not occur concurrently with other vehicle events (e.g.,
axle wind, suspension dynamic events and the like). Other advantages of the
deceleration dependent shift control are that it is functional for any gear ratio, and
that there are various exit criteria, providing improved flexibility in implementing
the control.
[0035] Those skilled in the art can now appreciate from the foregoing
description that the broad teachings of the present invention can be implemented
in a variety of forms. Therefore, while this invention has been described in
connection with particular examples thereof, the true scope of the invention
should not be so limited since other modifications will become apparent to the
skilled practitioner upon a study of the drawings, the specification and the
following claims.
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CLAIMS
What is claimed is:
1. A transmission control system for regulating operation of an automatic
transmission of a vehicle, comprising:
a first module that provides a predetermined shift schedule including
upshift and downshift lines;
a second module that offsets each of said upshift and downshift lines by
an offset amount to provide modified upshift and downshift lines when a
deceleration of said vehicle exceeds a threshold deceleration; and
a third module that regulates operation of said automatic transmission
based on said modified upshift and downshift lines.
2. The transmission control system of claim 1 further comprising a fourth
module that determines said offset amount based on at least one of a current
gear ratio of said automatic transmission and said deceleration.
3. The transmission control system of claim 1 wherein said offset amount is a
fixed, predetermined amount.
4. The transmission control system of claim 1 wherein said second module
stores a base downshift line vehicle speed, and sets said offset amount to zero
when a current vehicle speed falls below said base downshift line vehicle speed.
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5. The transmission control system of claim 1 wherein said second module
initiates a timer upon executing said step of offsetting, and sets said offset
amount to zero when said timer achieves a threshold time.
6. The transmission control system of claim 1 wherein said second module
sets said offset amount to zero when a throttle position exceeds a threshold
throttle position.
7. The transmission control system of claim 1 wherein said second module
monitors a vehicle speed, and decays said offset amount towards zero when said
vehicle speed accelerates back through said upshift lines.
8. The transmission control system of claim 7 wherein said second module
decays said offset amount based on a decay rate.
9. The transmission control system of claim 8 wherein said decay rate is a
predetermined, fixed value.
10. The transmission control system of claim 8 wherein said decay rate is
determined based on an acceleration of said vehicle.
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11. A method of regulating operation of an automatic transmission of a
vehicle, comprising:
providing a predetermined shift schedule including upshift and downshift
lines;
offsetting each of said upshift and downshift lines by an offset amount to
provide modified upshift and downshift lines when a deceleration rate of said
vehicle exceeds a threshold deceleration rate; and
regulating operation of said automatic transmission based on said
modified upshift and downshift lines.
12. The method of claim 11 further comprising determining said offset amount
based on at least one of a current gear ratio of said automatic transmission and
said deceleration rate.
13. The method of claim 11 wherein said offset amount is a fixed,
predetermined amount.
14. The method of claim 11 further comprising:
storing a base downshift line vehicle speed; and
setting said offset amount to zero when a current vehicle speed falls below
said base downshift line vehicle speed.
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15. The method of claim 11 further comprising:
initiating a timer upon executing said step of offsetting; and
setting said offset amount to zero when said timer achieves a threshold
time.
16. The method of claim 11 further comprising setting said offset amount to
zero when a throttle position exceeds a threshold throttle position.
17. The method of claim 11 further comprising:
monitoring a vehicle speed; and
decaying said offset amount towards zero when said vehicle speed
accelerates through said upshift lines.
18. The method of claim 17 wherein said decaying is achieved based on a
decay rate.
19. The method of claim 18 wherein said decay rate is a predetermined, fixed
value.
20. The method of claim 18 wherein said decay rate is determined based on
an acceleration of said vehicle.
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21. A method of regulating operation of an automatic transmission of a
vehicle, comprising:
monitoring an acceleration of said vehicle;
providing a predetermined shift schedule including upshift and downshift
lines;
entering an offset mode by offsetting each of said upshift and downshift
lines by an offset amount to provide modified upshift and downshift lines based
on said acceleration;
regulating operation of said automatic transmission based on said
modified upshift and downshift lines; and
exiting said offset mode when at least one of a plurality of exit conditions
exists.
22. The method of claim 21 further comprising determining said offset amount
based on at least one of a current gear ratio of said automatic transmission and
said deceleration rate.
23. The method of claim 21 wherein said offset amount is a fixed,
predetermined amount.
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24. The method of claim 21 further comprising storing a base downshift line
vehicle speed, wherein said step of exiting includes setting said offset amount to
zero when a current vehicle speed falls below said base downshift line vehicle
speed.
25. The method of claim 21 further comprising initiating a timer upon
executing said step of offsetting, wherein said step of exiting includes setting said
offset amount to zero when said timer achieves a threshold time.
26. The method of claim 21 wherein said step of exiting includes setting said
offset amount to zero when a throttle position exceeds a threshold throttle
position.
27. The method of claim 21 further comprising monitoring a vehicle speed,
wherein said step of exiting includes decaying said offset amount towards zero
when said vehicle speed accelerates through said upshift lines.
28. The method of claim 27 wherein said decaying is achieved based on a
decay rate.
29. The method of claim 28 wherein said decay rate is a predetermined, fixed
value.
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17
30. The method of claim 28 wherein said decay rate is determined based on
an acceleration of said vehicle.

A transmission control system for regulating operation of an automatic
transmission of a vehicle includes a first module that provides a predetermined
shift schedule including upshift and downshift lines and a second module that
offsets each of the upshift and downshift lines by an offset amount to provide
modified upshift and downshift lines when a deceleration of the vehicle exceeds
a threshold deceleration. A third module regulates operation of the automatic
transmission based on the modified upshift and downshift lines.

Documents:

00826-kol-2007-abstract.pdf

00826-kol-2007-assignment.pdf

00826-kol-2007-claims.pdf

00826-kol-2007-correspondence others 1.1.pdf

00826-kol-2007-correspondence others 1.2.pdf

00826-kol-2007-correspondence others 1.3.pdf

00826-kol-2007-correspondence others.pdf

00826-kol-2007-description complete.pdf

00826-kol-2007-drawings.pdf

00826-kol-2007-form 1.pdf

00826-kol-2007-form 18.pdf

00826-kol-2007-form 2.pdf

00826-kol-2007-form 3.pdf

00826-kol-2007-form 5.pdf

00826-kol-2007-gpa.pdf

00826-kol-2007-priority document.pdf

826-KOL-2007-(09-11-201)-PETITION UNDER RULR 137.pdf

826-KOL-2007-(09-11-2011)-ABSTRACT.pdf

826-KOL-2007-(09-11-2011)-AMANDED CLAIMS.pdf

826-KOL-2007-(09-11-2011)-DESCRIPTION (COMPLETE).pdf

826-KOL-2007-(09-11-2011)-DRAWINGS.pdf

826-KOL-2007-(09-11-2011)-EXAMINATION REPORT REPLY RECIEVED.pdf

826-KOL-2007-(09-11-2011)-FORM 1.pdf

826-KOL-2007-(09-11-2011)-FORM 2.pdf

826-KOL-2007-(09-11-2011)-FORM 3.pdf

826-KOL-2007-(09-11-2011)-FORM 5.pdf

826-KOL-2007-(09-11-2011)-OTHERS.pdf

826-KOL-2007-(09-11-2011)-PA.pdf

826-KOL-2007-(23-05-2012)-CORRESPONDENCE.pdf

826-kol-2007-CORRESPONDENCE.pdf


Patent Number 254377
Indian Patent Application Number 826/KOL/2007
PG Journal Number 44/2012
Publication Date 02-Nov-2012
Grant Date 30-Oct-2012
Date of Filing 29-May-2007
Name of Patentee GM GLOBAL TECHNOLOGY OPERATIONS, INC.
Applicant Address 300 GM RENAISSANCE CENTER DETROIT, MICHIGAN
Inventors:
# Inventor's Name Inventor's Address
1 JAYSON S. SCHWALM 25245 ARDEN PARK DRIVE FARMINGTON HILLS, MICHIGAN 48336
2 CHRISTOPHER A. SPANGLER 473 NORTH MANSFIELD YPSILANTI, MICHIGAN 48197
3 ANDRIY NIKITIN 2601 BULLARD ROAD HARTLAND, MICHIGAN 48353
4 DAVID W. WRIGHT 1405 CATHERINES WAY HOWELL, MICHIGAN 48843
PCT International Classification Number F16H61/02, 61/21
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/815,147 2006-06-20 U.S.A.