This invention relates to a method/system for controlling upshifting in an
automated mechanical transmission systems.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This present invention relates to improved shift logic for an automated vehicular
mechanical transmission system. In particular, the present invention relates to a
control method system having logic rules whereby an upshift under certain
vehicle operating conditions will result in temporarily modifying the shift schedule
to minimize the occurrence of unwanted multiple upshifting.
DESCRIPTION OF THE PRIOR ART
Fully and partially automated vehicular mechanical transmission systems are
known in the prior art, as may be seen by reference to U.S.Pats. No. 4,361,060;
4,595,986; 4,648,290; 5,109,721; 5,393,276; 5,409,432 and 5,425,284, the
disclosures of which are incorporated herein by reference. Such transmissions
having an automatic shift mode typically base shift decisions upon shift point
profiles or shift schedules, which often are graphically represented on a graph of
throttle position versus engine or vehicle speed. It is known to temporarily modify
these shift profiles in view of various sensed vehicle operating conditions to
modify vehicle performance, for antihunt purposes or the like. Examples of such
shift logic may be seen by reference to U.S.Pats. No. 4,361,060; 4,551,802;
4,852,006; 4,916,979; 5,053, 963, and 5,406,861, the disclosures of which are
incorporated herein by reference.
A problem not addressed by the prior art shift logic involves unwanted, repetitive
upshifting which often occurred after a desired upshift, typically a full-or
substantially full-throttle upshift, if the vehicle operator then let up on the throttle.
This problem is of special concern in light-and medium-duty trucks and other
vehicles (MVMA Class 2-6 vehicles) having 5-to-8-forward-speed transmissions
and utilizing gasoline or diesei engines having a governed top speed of about
2600 RPM, rather than heavy-duty vehicle diesei engines typically coupled to 10-
to-18-speed transmissions and governed to about 1900 RPM.
SUMMARY OF THE INVENTION
In accordance with the present invention, a new and improved automated
change-gear shift control, including improved upshift control logic, is provided.
This is accomplished by providing logic rules whereby, under certain operating
conditions and/or operator actions, the normally utilized upshift schedule is
modified to prevent unwanted, repetitive upshifts. By way of example, after an
upshift, if throttle is above a certain reference value, the normally instituted
upshift shift points are increased for a period of time or until engine speed falls
below a reset reference value.
Accordingly, it is an object of the present invention to provide a new and
Improved automated change-gear transmission shift control system/method.
This and other objects and advantages of the present invention will become
apparent from a reading of the following description of the preferred embodiment
taken In connection with the attached drawings:
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 is a schematic illustration of an at least partially automated vehicular
mechanical transmission system utilizing the control logic of the present
invention.
Fig. 2 is a schematic illustration, in graphical format, of a traditional shift schedule
for a medium-duty vehicle.
Fig. 3 is a schematic Illustration, similar to Fig. 2 and in graphical format, of the
shift schedule according to the control logic of the present invention.
Fig. 4 is a schematic illustration, inflow chart format, of the upshift control logic of
the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 illustrates a vehicle drtveline 10 including an at least partially automated
mechanical transmission system 12 utilizing the upshift control logic of the
present invention. Powertrain 10 includes an internal combustion engine 14
(such as a gasoline or diesel engine), a master clutch 16, a mechanical
transmission 18 (such as a S-to-7-speed, medium-duty transmission), and a drive
axle assembly 20 driven by propeller shaft 21. While the present invention is
particularly well suited for medium-duty vehicles, it is not so limited.
Transmission 18 may be of a standard 5-,6-,7-,9-,10-, 12- or greater forward
speed design. Examples of such transmissions may be seen by reference to U.S.
Pats. No. 4,373,403; 4,754,665; and 5,390,561, the disclosures of which are
incorporated herein by reference.
The automated transmission system 12 preferably will include a microprocessor-
based controller 22 for receiving various input signals 24 and processing same
according to logic rules to issue command output signals 26 to various system
actuators. Controllers of this type are known, as may be seen by reference to
aforementioned U.S.Pats. No. 4,361,060 and 4,595,986.
A throttle position sensor 28 provides a signal THL indicative of operator-set
throttle position, a shift selector 30 provides a signal GRS indicative of selected
transmission operating mode and/or of a request for an up- or downshift for a
currently engaged ratio, speed sensors 32, 34 and 36 provide signals ES, IS and
OS, respectively, indicative of the rotational speed of the engine crank shaft 38,
the transmission input shaft 40 and the transmission output shaft 42,
respectively.
An engine controller 44 is provided for controlling speed or torque of the engine,
a clutch actuator 46 is provided for controlling operation of the master clutch, and
a transmission operator 48 is provided to control shifting of the transmission.
The ECU 22 may be separate or integral with the engine controller 44. The
various controllers, sensors and/or actuators may communicate over a data bus
conforming to an industry standard protocol, such as SAE J-1939 or the like.
Suitable sensors and actuators are known to those of ordinary skill in the art and
examples thereof, not intended to be limiting, may be seen by reference to U.S.
Pats. No. 4,361,060; 4,873,881; 4,974,468;5,135,218; 5,279,172; 5,305,240;
5,323,669; 5,408,898; 5,441,137, 5,445,126; 5,448,483 and 5,481,170.
As is known, in automated transmission system of this type, when operating in an
automatic shifting mode ("D" on selector 30), upshifts and downshifts are
commanded according to a "shift schedule" or "shift point profile", a prior art
version of which is illustrated in Fig. 2. Shift schedules, or the functional
equivalents thereof, typically are stored in the memories of the controllers 22.
In Fig. 2, line 54 represents the upshift profile and line 56 represents the
downshift profile. As a point representing engine speed and throttle pedal
displacement crosses line 54 from area 58 in between lines 54 and 56 to area 60
above line 54, an upshift is commanded. As a point representing engine speed
and throttle pedal displacement crosses line 56 from area 58 to area 62 below
line 56, a downshift is commanded. As is also known, at relatively high throttle
position, also referred to as at full or substantially full throttle (90 to 100%
displacement), the upshift profile 54 is elevated (see portion 54A of line 54). After
an upshift, assuming relatively constant vehicle speed, the RPM of engine will
decrease by an amount determined by the ratio steps. Line 64 represents the
expected engine speeds after an upshift.
A problem with the prior art shift schedules occurred if a full-throttle (i.e., greater
than about 90% throttle displacement) upshift occurred and then the operator
removed his foot from the throttle pedal, causing a low throttle (less than about
30% throttle) condition. This would cause a second, unintended upshift to be
commanded.
By way of example, if an upshift was commanded at point 66, the RPM would
then decrease to point 68. If the operator then removed his foot from the throttle
pedal, the operating point would be point 70, at which a second, unintended
upshift would be commanded.
The shift schedule of the present invention is schematically illustrated in Fig. 3.
Fig. 3 is similar to Fig. 2, and functionally similar or identical elements are given
like reference numerals and will be only briefly discussed.
Fig. 3 defines areas 58, 60 and 62 which are separated by upshift line 54 and
downshift line 56. Line 64 indicates the expected engine rotational speed (RPM)
after an upshift. Points 66, 68 and 70 represent, respectively, operating points at
a full-throttle upshift, after a full-throttle upshift, and when throttle is released.
The shift logic of Fig.3 differs from that of Fig. 2 in that after a full-throttle upshift,
a modified upshift line 72 is invoked. It is noted that the modified upshift line 72
will not cause operation at point 70 (i.e., releasing the throttle pedal after a full-
throttle upshift) to result in a command for a second, probably unwanted upshift.
The modified upshift profile 72 preferably will remain effective after a full-throttle
upshift until a predetermined condition occurs, such a time period expiring and/or
engine rotational speed falling below a reset value 74. The modified upshift
profile 72 has increased upshift engine RPM values in at least the lower (30%
throttle or less) throttle positions.
Fig. 4 is a flow chart representation of the shift logic of Fig. 3.
Accordingly, it may be seen that a new and improved control system/method for
controlling upshifting in a fully or partially automated mechanical transmission is
provided.
Although the present invention has been described with a certain degree of
particularity, it is understood that the description of the preferred embodiment is
by way of example only and that numerous changes to form and detail are
possible without departing from the spirit and scope of the invention as
hereinafter claimed.
WE CLAIM
1. A method for controlling upshifting in a vehicular automated mechanical
transmission system (12) comprising a fuel-controlling engine (14), a
manually controlled device for providing a signal indicative of requested
engine fueling (28), and a change-gear transmission (18) having an input
shaft (40) driven by said engine and an output shaft, said transmission
having a plurality of selectable ratios of input shaft rotational speed to
output shaft (42) rotational speed, a controller (22) for receiving a plurality
of input signals (24) having (i) a first input signal indicative of the rotational
speed of at least one of said engine, input shaft and output shaft, and (ii) a
second input signal (THL) indicative of the operator's requested engine
fueling and for processing said signals in accordance with logic rules to
issue command output signals (26) to system actuators (44,46,48), said
logic rules causing an upshift to be commanded if at given sensed value of
said second signal, said first signal exceeds an upshift reference value for
said given value of said second signal, said method comprising:
establishing a default first value for said upshift reference values;
characterized in that upon sensing an upshift occurring when said second
signal exceeds a full-throttle reference value, causing the upshift reference
values for at least those second signal values less than a low-throttle
reference value to equal a modified second value (72), said modified
second value exceeding said default first value; and
after sensing the occurrence of a reset event, causing said upshift
reference values to be reset to the default first values thereof.
2. The method as claimed in claim 1, wherein said controller is
microprocessor-based.
3. The method as claimed in claim 1, wherein said full-throttle reference
value is about 90% of full throttle.
4. The method as claimed in claim 1, wherein said low-throttle reference
value is about 20% of full throttle.
5. The method as claimed in claim 1, wherein said reset event comprises a
passage of time from sensing said upshift occurring when said second
signal exceeds said full-throttle reference value.
6. The method as claimed in claim 1, wherein said reset event comprises
said first signal being less than a reset reference value.
7. The method as claimed in claim 1, wherein said first signal is indicative of
engine rotational speed.
8. The method as claimed in claim 2, wherein said first signal is read by said
controller from an electronic data link.
9. An improved method for controlling an automatic transmission system for
devices having a throttle-controlled engine, an operator-actuated throtting
control means, and a transmission having a plurality of gear ratio
combinations selectively engageable between a transmission input shaft
and a transmission output shaft, said transmission input shaft being
operativety connected to said engine, said transmission system
comprising an information processing unit having means for receiving a
plurality of input signals including (I) an input signal indicative of the
position of said throttle controlling means and (ii) an input signal indicative
of the rotational speed of said engine, said processing unit including
means for processing said input signals in accordance with a program to
provide a predetermined gear ratio for a given combination of input signals
and for generating output signals whereby said transmission system is
operated in accordance with said program, and means associated with
said transmission effective to actuate said transmission to effect
engagement of one of said gear ratio combinations in response to said
output signals from said processing unit, the improved method comprising:
sensing the presence or absence of an upshift occurring at substantially
full throttle conditions; and
modifying said program by increasing the engine speed at which an
upshift will be commanded at substantially low throttle conditions in
response to said processing unit sensing the presence of an upshift
occurring at substantially full throttle conditions.
10.The improved method as claimed in claim 9, wherein substantially full
throttle conditions are sensed if said throttle control is about 90% or
greater of maximum throttle position and substantially low throttle
conditions are those conditions where said throttle is about 30% or less of r
maximum throttle position.
11. A control system for controlling up shifting in a vehicular automated
mechanical transmission system (12) comprising a fuel-controlled engine
(14), a manually controlled device for providing a signal indicative of
requested engine fueling (28), and a change-gear transmission (18)
having an input shaft (4) driven by said engine and an output shaft (42),
said transmission having a plurality of selectable ratios of input shaft
rotational speed to output shaft rotational speed, a controller (22) for
receiving a plurality of input signals (24) having (i) a first input signal (ES,
IS, OS) indicative of the rotational speed of at least one of said engine,
input shaft and output shaft, and (ii) a second input signal (THL) indicative
of the operator's requested engine fueling and for processing said signals
in accordance with logic rules to issue command output signals (26) to
system actuators (44, 46 and/or 48), said logic rules causing an upshift to
be commanded if at given sensed value of said second signal, said first
signal exceeds an upshift reference value for said given value of said
second signal, said control system characterized by said logic rules
comprising rules for:
establishing a default first value (54) for said upshift reference values;
upon sensing an upshift occurring when said second signal exceeds a full-
throttle reference value, causing the upshift reference values for at least
those second signal values less than a low-throttle reference value to
equal a modified second value (72), said modified second value
exceeding said default first value; and
After sensing the occurrence of a reset event, causing said upshift
reference values to be reset to the default first values thereof.
12.The control system as claimed in claim 11 wherein said controller is
microprocessor-based.
13.The control system as claimed in claim 11, wherein said full-throttle
reference value is about 90% of full throttle.
14.The control system as claimed in claim 11, wherein said low-throttle
reference value is about 20% of full throttle.
15. The control system as claimed in claim 11, wherein said reset event
comprises a passage of time from sensing said upshift occurring when
said second signal exceeds said full-throttle reference values.
16. The control system as claimed in claim 11, wherein said reset event
comprises said first signal being less than a reset reference value (74).
17. The control system as claimed in claim 11, wherein said first signal is
indicative of engine rotational speed (ES).
18. The control system as claimed in claim 12, wherein said first signal is
ready by said controller from an electronic data link.

A method for controlling upshifting in a vehicular automated mechanical
transmission system (12) comprising a fuel-controlling engine (14), a manually
controlled device for providing a signal indicative of requested engine fueling
(28), and a change-gear transmission (18) having an input shaft (40) driven by
said engine and an output shaft, said transmission having a plurality of selectable
ratios of input shaft rotational speed to output shaft (42) rotational speed, a
controller (22) for receiving a plurality of input signals (24) having (i) a first input
signal indicative of the rotational speed of at least one of said engine, input shaft
and output shaft, and (ii) a second input signal (THL) indicative of the operator's
requested engine fueling and for processing said signals in accordance with logic
rules to issue command output signals (26) to system actuators (44,46,48), said
logic rules causing an upshift to be commanded if at given sensed value of said
second signal, said first signal exceeds an upshift reference value for said given
value of said second signal, said method comprising: establishing a default first
value for said upshift reference values; characterized in that upon sensing an
upshift occurring when said second signal exceeds a full-throttle reference value,
causing the upshift reference values for at least those second signal values less
than a low-throttle reference value to equal a modified second value (72), said
modified second value exceeding said default first value; and after sensing the
occurrence of a reset event, causing said upshift reference values to be reset to
the default first values thereof.