AU759923B2 - A shift control method for an automatic transmission of a vehicle - Google Patents

A shift control method for an automatic transmission of a vehicle Download PDF

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Publication number
AU759923B2
AU759923B2 AU93414/01A AU9341401A AU759923B2 AU 759923 B2 AU759923 B2 AU 759923B2 AU 93414/01 A AU93414/01 A AU 93414/01A AU 9341401 A AU9341401 A AU 9341401A AU 759923 B2 AU759923 B2 AU 759923B2
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Australia
Prior art keywords
atmospheric pressure
shift
shift control
duty
predetermined
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AU93414/01A
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AU9341401A (en
Inventor
Chang-Gi Yeo
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Hyundai Motor Co
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Hyundai Motor Co
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/02—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used
    • F16H61/0202—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric
    • F16H61/0204—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal
    • F16H61/0213—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing characterised by the signals used the signals being electric for gearshift control, e.g. control functions for performing shifting or generation of shift signal characterised by the method for generating shift signals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/04—Smoothing ratio shift
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H59/00—Control inputs to control units of change-speed-, or reversing-gearings for conveying rotary motion
    • F16H59/60—Inputs being a function of ambient conditions
    • F16H59/62—Atmospheric pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/04—Smoothing ratio shift
    • F16H61/06—Smoothing ratio shift by controlling rate of change of fluid pressure
    • F16H61/061—Smoothing ratio shift by controlling rate of change of fluid pressure using electric control means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/10—Controlling shift hysteresis

Description

I p
AUSTRALIA
Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT
ORIGINAL
Name of Applicant: Actual Inventor: Address for Service: Invention Title: Details of Basic Application(s): HYUNDAI MOTOR COMPANY Chang-Gi YEO HODGKINSON OLD McINNES Patent Trade Mark Attorneys Levels 3 and 4, 20 Alfred Street MILSONS POINT NSW 2061 A Shift Control Method for an Automatic Transmission of a Vehicle 2000-0071895 2001-0032822 November 30, 2000 June 12, 2001 Republic of Korea The following statement is a full description of this invention, including the best method of performing it known to me/us: 1928CE A SHIFT CONTROL METHOD FOR AN AUTOMATIC TRANSMISSION OF A
VEHICLE
CROSS-REFERENCE TO RELATED APPLICATION This application claims prioritiesb o f Korea patent Application No. 2000-0071895, filed on November 30,.2000, and Korea patent Application No.
10-2001-0032822, filed on June 12, 2001.
BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a shift control method for an automatic transmission of a vehicle, and more particularly, to a shift control method for an automatic transmission for re-setting values of Sshift-controI variables according to an altitude of the vehicle driving.
15 Description of the Related Art Generally,; an automatic transmission is exposed to various driving •conditions. A transmission control unit determines a most preferable shiftspeed under the driving conditions and performs a speed shift to the determined shift-speed.
Whether a speed shift to a target shift-speed is necessary is determined based on a shift-pattern, which includes an upward shift-pattern for determining that an upward shift is necessary and a downward shift-pattern for determining that a downward shift is necessary. As examples of the upward shift-pattern and the downward shift pattern, FIG. 1 shows the upward and downward shiftpatterns between a second and a third shift-speed.
Each of the 3-*2 and 2--3 shift-patterns forms a line. When a drivingstate determined by a vehicle speed Vs and a throttle valve open-angle TH crosses over the 3-2 shift-pattern, a speed shift to the second speed is necessary if the third shift-speed is currently engaged. When a driving-state crosses over the 2-3 shift-pattern, a speed shift to the third speed is' necessary if the second shift-speed is currently engaged.
Therefore, when the driving-state is to the right of the 2-*3 shiftpattern, the third shift-speed is engaged, and when the driving-state is to .the left of the 3-*2 shift-pattern, the second shift-speed is engaged.
When the ,driving-state is between the 3-2 and 2-*3 shift-patterns, a target shift-speed is determined based on. a hysteresis, of the,.drivingstate change. When the driving state of the vehicle currently corresponds to a point A of FIG. 1, the driving state is changed to a point B if the throttle valve open- :i angle TH is reduced as an accelerator pedal is released. In this case, a speed shift to the third speed begins if the vehicle is currently running in the second shift-speed. This kind of speed shift, an upward speed shift caused by the throttle valve open-angle being reduced, is called a lift-foot-up shift (referred to as "LFU" hereinafter).
To the contrary, when the driving state of the vehicle currently corresponds to a point C, the driving state is changed to a point D if the throttle valve open angle TH is increased as the accelerator pedal is depressed. In this case, a speed shift to the second speed begins if the vehicle is currently running in the third shift-speed. This kind of speed shift, a downward speed shift caused by the throttle valve open-angle being increased, is called a kickdown shift.
The upward..shift-pattern is usually modified when the vehicleisrunning.
on a slope in order to hold the shift-speed in a lower one such that sufficient engine power can be utilized. Modification factors used for modifying the shiftpattern are determined on the basis of the slope. FIG. 2A shows an example of the modification factors, and FIG. 2B o1 shows an upward shift-pattern modified under the modification factors.
As shown in FIG. 2A, the modification factors include a modification i limit RSU for defining a maximum amount of modification, .a minimum slope RSO'for modifying the shift-pattern, and a maximum slope RS1i.at,,which the shift-pattern is modified by the modification limit RSU:"
S
.15 That is, the shift-pattern is not modified When the slope of a road is less than the minimum slope RSO, the shift-pattern is modified by the modification limit RSU when the slope is larger than the maximum slope RS1, and the shift pattern is modified increasingly as the slope increases when the slope is o. between the minimum and maximum slopes RSO and RS1.
The solid line 210 of FIG. 2B denotes a 2-*3 shift-pattern for a level road, and the dotted line 220 denotes a modified 2-3 shift-pattern on a slope. When the slope is larger than the minimum slope RSO, the shiftpattern is modified in a rightward direction in FIG. 2B, and the amount of the modification increases as the slope increases.
According to the modified shift-pattern 220, a lift-foot-up shift is prohibited even if. the vehicle driving state is changed from the point A to the point B by releasing the accelerator pedal.
A shift control method for a kick-down shift is described hereinafter-with.-a.nexample .of 3-2 kick-down shift. A friction,.element for operating in the third shift-speed (referred to as "release-element" hereinafter) is released during a 3-2 kick-down shift-control, and a friction element for operating in the second shift-speed (referred to as "apply-element" hereinafter) is controlled to engage during the 3-2 kick-down shift-control.... i *For those operations, hydraulic pressure being supplied to the..
release-element in the third shift-speed is released and hydraulic pressure is newly supplied to the apply-element, which is realized by controlling solenoid valves included in a hydraulic circuit forcontroll,ing 15 hydraulic fluid supply. An example of a duty map of the solenoid valves for releasing the release-element and for engaging the apply-element is shown in FIG. 3.
Lines 310 and 320 respectively represent a release duty and an engaging duty, the release duty denoting the duty for releasing hydraulic pressure of the release-element, the engaging duty denoting the duty for supplying hydraulic pressure to the apply-element.
Control variables for hydraulic pressure release of the releaseelement include an initial release-duty Dsr for suddenly lowering the duty for hydraulic pressure supplied to the release-element, a rampcontrol slope dDr for gradually decreasing the release duty for the release-element from the initial release-duty Dsr, and a high-holding duty Dcr for holding the duty at a higher lever than the duty at an end of the ram p-controlling. Control variables for hydraulic pressure supply to the applyelement include a low-holding duty Da for holding a low level pressure to reduce an engaging shock of the apply-element, and a transition duty De for supplying sufficient hydraulic pressure to prevent slip of the apply-element.
The density of the air that comes into the engine changes o according to the altitude of vehicle driving, which causes changes in oo*o engine power. However the prior art does not take the altitude into account in a shift control- method for an automatic transmission of a 15 vehicle, especially for a shift control method related to lift-foot-up shift and kick-down shift.
*"*Therefore, there has been a need to provide an effective and appropriate shift control method for appropriately preventing a lift-footup shift at a high altitude and for controlling a kick-down shift according to a vehicle driving altitude.
That is, there- has been a need to prevent a low atmospheric pressure at a high altitude from causing an operating hydraulic pressure for a speed shift to become relatively high, accordingly to prevent shift shock at high altitude, and to prevent a lift-foot-up shift on a slope at a high altitude, accordingly to have the vehicle provided with sufficient driving force.
SUMMARY OF THE INVENTION The present invention has been made in an effort to solve the above problem.
It is an object of the present invention to provide a shift control method for an automatic transmission for preventing a lift-foot-up shift on a slope and for appropriately controlling a kick-down shift when a vehicle equipped with the automatic transmission is driving at a high altitude.
According to a first aspect the present invention there is provided a shift control method for an automatic transmission of a vehicle comprising: detecting atmospheric pressure; determining whether a predetermined atmospheric pressure applying condition is satisfied; and resetting values of shift control variables based on the detected atmospheric pressure when the predetermined atmospheric pressure applying condition is satisfied, wherein the shift control variables of which the values are comprise at least one of a modification limit RSU for defining a maximum amount of a modification of an upward shift-pattern, a minimum slope RSO for modifying the upward shift-pattern, and a maximum slope RS1 at which the upward shift pattem is modified by the modification limit RSU.
The values of shift control variables are reset to be appropriate for an extant atmospheric pressure range, the extant atmospheric pressure range being selected from a plurality of atmospheric pressure ranges formed on the basis of a plurality of predetermined reference atmospheric pressures.
"0 Preferably, the shift control method further comprises determining whether an upward speed shift is necessary based on the reset values of shift control variables.
The shift control method of the present invention further comprises determining whether a predetermined kick-down shift condition is satisfied, and performing a 9"9 downshift based on the reset values of shift control variables when the kick-down shift condition is satisfied.
*The shift control variables of which the values are reset comprise at least one of an initial release-duty Dsr for suddenly lowering a release duty for hydraulic pressure supplied to a release-element, a ramp control slope dDr for gradually decreasing the release duty for the release-element from the initial release-duty Dsr, 6 and a high-holding duty Dcr for holding duty at a higher lever than a final duty of the ramp-control.
Furthermore, the shift control variables of which the values are reset further comprise at least one of a low-holding duty Da for holding a low level pressure to reduce an engaging shock of an apply-element, and a transition duty De for supplying sufficient hydraulic pressure to prevent slip of the apply-element.
The atmospheric pressure applying condition includes the automatic transmission not undergoing shifting, and the determining whether the predetermined atmospheric pressure applying condition is ooo* ooo o* o •o •coo :0.:o 0 satisfied determines that the predetermined atmospheric pressure applying condition is not satisfied if the automatic transmission is undergoing shifting.
The atmospheric pressure applying condition preferably includes a- .Ghange,- rate of- .the throttle valve open-angle- being.,-with.in.- apredetermined change rate range, and the determining whether the predetermined atmospheric pressure applying condition is satisfied Sdetermines t hat the predetermined atmospheric pressure -'applying condition is not satisfied if the change rate of the throttle valve -openio.0 :-angle is out of the predetermined change rate range'. The atmospheric pressure applying condition further includes the detected atmospheric pressure not being abnormal; and.,ac.cordingly the -detetrmining.:whether the predetermined atmospheric pressurei-applying coi d ition is satisfied determines that the -pedetermirnedatmospheric 1soo 5 pressure applying condition is satisfied only if the detected atmospheric Spressure is not abnormal, and the determining whether the predetermined atmospheric pressure applying condition is satisfied comprises resetting the detected atmospheric pressure as a predetermined atmospheric pressure if the detected atmospheric pressure is abnormal.
The detected atmospheric pressure can be determined to be abnormal when an error exists in a communication line between a transmission control unit and an atmospheric pressure detector, or when the atmospheric pressure detector is determined to be malfunctioning.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows upward and downward shift-patterns between a second and a third shift-speeds, as examples of upward and downward shift patterns.
FIG. 2A shows an example of slope dependency of modification factors for being. usedfor rn~difying,a shift-pattern, and FIG. 2B shows an. example an upward shift-pattern modified under the modification factors.
FIG. 3 is an example of a duty map of solenoid valves for releasing release-element and for engaging an apply-element4., FIG. 4 is a block diagram of a shift control apparatus in which a o shift control method according to a preferred embodiment of the present invention is performed.
FI. jsa flowchart of a shift control method according,tp,o a preferredembodiment of the present invention.' DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSI. 15 Hereinafter, a preferred embodiment of the present invention'will be described in detail with reference to the accompanying drawings.
FIG. 4 is a block diagram of a shift control apparatus in which a shift control method according to a preferred embodiment of the present S: invention is performed.
As shown in FIG. 4, the shift control apparatus according to a preferred embodiment of the present invention includes a driving-state detecting unit 400 for detecting a plurality of driving-state factors of a vehicle equipped with an automatic transmission such as vehicle speed and throttle valve open-angle, a transmission control unit 450 (referred to as "TCU" hereinafter) for receiving the detected driving-state factors from the driving-state detecting unit 400 and for controlling a speed shift of the automatic transmission based on the received driving-state factors, and an actuator unit 470 disposed in the automatic transmission for performing-a speed..shift.according to control signals receivedfromr., the TCU 450.
The driving-state detecting unit 400 includes a vehicle speed, detector 410 for detectin'g a vehicle speed, a throttle valve open-angle.: detector 415 for detecting an open-angle of a throttle valve, a turbinespeed detector 420- .for. detecting a revolution speed of a turbine disposed in a torque converter of the automatic transmission, an enginespeed detector 425 for.detecting a revolution speed of an engine of the vehicle, and an atimospheric pressure detector 430 for detecting atmospheric press.ure t the altitude At which the vehicle is driving •Is 15 The atmospheric pressure detector 430 can be realized by a sensor disposed outside of the engine for directly detecting atmospheric pressure. As for a vehicle that measures an inducted mass of air by a manifold absolute pressure (MAP) method, a MAP sensor used to detect the manifold absolute pressure can be used for the atmospheric pressure detector 430, and an atmospheric pressure can be calculated based on the output signal of the MAP sensor.
The TCU 450 is realized as a microprocessor activated by a predetermined program, and includes a memory 460 to store variable values to be used for speed shifts.
More particularly, the memory 460 stores variable values including a modification limit RSU, a minimum slope RSO, and a maximum slope RS1 for being used as modification factors of a shift-pattern according to a slope.
Further, the memory 460 stores variable values including an initial 5 release-duty Dsr, a ramp-control.slope dDr, and a-high-holding duty Dcr for being used as control variables for controlling a release-element in a kick-down shift, and also stores variable values including a low-holding duty Da and a transition duty De for being ued'as control variables for controlling an applyelement in the kick-down shift.
Detailed descriptions of functions of the variables are omitted because they are the same as already described in the description of the related art.
A shift control method for an automatic transmission according to a preferred embodiment is hereinafter described in detail with reference toFPIG: Firstlyi thieOTCU:450''detects,an atmospheric pressure Pa at step'SS05-.. 15 At step S505, the TCU 450 can detect the atmospheric pressure by receiving a correspondent signal from the atmospheric pressure detector 430 of the driving- •state detecting unit 400, or by calculating the atmospheric pressure based on a correspondent signal from a MAP sensor included for a vehicle measuring a mass of the inducted air by a MAP method, or by receiving an atmospheric pressure signal from a control unit if the atmospheric pressure detector 430 includes the control unit for controlling other equipment such as an engine of the vehicle.
Subsequently the TCU 450 determines whether an atmospheric pressure applying condition is satisfied at step S510. The atmospheric pressure applying condition is a predetermined condition for being used to determine whether the detected atmospheric pressure Pa is applied in a shift control of the automatic transmission.
In order to determine whether the atmospheric pressure applying 5.-condition is satisfied, the TCU 450. determines.-whether..the..transmission is undergoing shifting at step S515.
Whether the transmission is undergoing shifting or not is determined upon whether the actuator unit 470 is under, shift-operations, that is, upon whether the TCU 450 is sending shift-control signals to the actuator unit 470.
1o .If it is-determined that the transmission: is undergoing shifting at step S515, the shift control method according to the present invention terminates, and if it is determined that the transmission is not undergoing shifting, the TCU S: 5. 450 determines whether a change rate ATH .of the throttle"valve openanglfe TRHliies' within a predetermined range of a thrttievalve- ipenangle change rate at step S520.
'If it is determined that the change rate ATH is nt within the predetermined range at step S520, the shift control method according to the present invention terminates because the detected value of the atmospheric pressure detector 430 may have a significant error if the throttle valve open-angle TH varies rapidly.
Therefore, the predetermined range of the throttle valve openangle change rate may be set as any range in which the atmospheric pressure detector 430 does not produce significant error.
If the change rate ATH is determined to be within the predetermined range at step S520, the TCU 450 determines whether the detected atmospheric pressure Pa is abnormal at step S525.
The detected atmospheric pressure Pa is determined to be abnormal 5 when. an.error.-exists in a communication line between-theT-CU-.450-.and the atmospheric pressure detector 430, or when the atmospheric pressure detector 430 is determined to be malfunctidning'. The error in ";othe'.ommunication line between the TCU 450 "ahdd Athe.,atmospheric pressure detector 430 can be detected by any method of the p'rior art for detecting an error of a communication line, and,thA malf~urictioning of the atmospheric pressure detector 430 can be monitored by any method S. known as a prior art. S "W i:When the detected atmospheric pres~urf 'Pa is determined to be ;,-;iabnormnal at step S525, the TCU 450 resets tlhi valueofi the detected atmospheric pressure Pa as a predetermined standard pressure at step SS530 and resets values of the shift control variables according to the predetermined standard pressure at step S535, and subsequently the shift control method of the present invention, terminates. The predetermined standard pressure is defined, for example, as 760 mmHg, an average atmospheric pressure at sea level, and the resetting values of the shift control variables at step S535 can be performed in the same way as resetting values of the shift control variables at step S540.
When the detected atmospheric pressure Pa is determined as not being abnormal at step S525, the TCU 450 resets values of the shift control variables based on the detected atmospheric pressure Pa at step S540.
In step S540, the values of the shift control variables are reset to be appropriate for the extant atmospheric pressure Pa within a predetermined range,,th.e,,corresporndent atmospheric pressure range being seje,..edfrpmA, plurality, of atmospheric pressure ranges formed on the basis of a plurality-of predetermined reference atmospheric pressures. T he .shift. control variables of which the values are reset-, nclude :a modification limit RSU for defining a maximum amount of a modification of an o 1: upward shift-pattern, a minimum slope RSO for modifying ,the upward shiftpattern, and a maximum slope RS1 at which the upward shift pattern is modified by the modification limit RSU..
Fu.rther,,the shift control variables of which the yalues :are ,eset *o include a,1.initial release-duty Dsr for suddenly, oweringa .reIease.duty 15 for hydraulic pressure supplied to a release-element at a moment that shifting begins, a ramp-control slope dDr. for gradually decreasing the release duty for the release-element from the initial release-duty Dsr, a high-holding duty Dcr for holding duty at a higher lever than a final duty Sof the ramp-control, a low-holding duty Da for holding a low level pressure to reduce an engaging shock of an apply-element, and a transition duty De for supplying sufficient hydraulic pressure to prevent slip of the apply-element.
The step S540 of resetting values of the shift control variables is described in more detail hereinafter.
The TCU 450 stores a first reference pressure P1 and a second reference pressures P2 in the memory 460 as the plurality of predetermined reference atmospheric pressures.
Therefore, a whole atmospheric pressure range is divided, by the first and second..reference,.pressures .P1 and P2, into three ranges.of.a,- first range wherein the atmospheric pressure is larger than or equal.to the first reference pressure P1, which is referred to as "low altitude range" hereinafter~iads"'e'o'nd.range wherein the atmospheric pressure.Jlis.,,-. less than the first reference pressure.P1 but larger than or equal to the second reference pressure P2, which is referred to as "intermediate.--,: altitude range" hereinafter, and a third range wherein the atmospheric S. pressure is less than the second reference pressure P2, which is...
referred to ast "highi altitude range" hereinafter.
For example.:the first reference pressure P1 is predetermined to be 642.41 mmHg, a pressure lower than an average pressure at sea level, and the second reference pressure P2 is predetermined to be 535.11 mmHg, less than the first reference pressure by 107.3 mmHg.
The memory 460 of the TCU 450 includes a register to store a *o value denoting which ranges the detected atmospheric pressure Pa corresponds to, and the register stores a value denoting one of the "high altitude range", the "intermediate altitude range", and the "low altitude range" in the memory.
Moreover, values of the shift control variables for each of the three atmospheric pressure ranges are stored in the memory 460. That is, the values of the shift control variables are stored separately according to the "high altitude range", the "intermediate altitude range", and the "low altitude range".
Therefore, the TCU determines whether the detected atmospheric pressure Pa is larger than or equal to the first reference pressure P1 at step S545, and stores a value denoting ihe l'ow altitude range" in the register at step S550 if the detected atmospheric pressure Pa is larger than or equal to the first reference pressure P1.
If the detected atmospheric, pressure Pa is determined to be less than the first reference pressure P1 at step S545, the TCU determines whether the detected atmospheric',.pressure,.Pa is larger than or equal to the second of: reference pressure at step S555, and stores a value denoting the "intermediate 4 altitude range" in the register.at. step S560 if the detected atmospheric pressure Pa is determined to be-larger than.or equal to the second reference pressure P2- at step S 555. 15 If the detected atmospheric pressure Pa is determined to be less than the second reference pressure P2 at step S555, the TCU 450 stores a value denoting the "high altitude range" in the register at step S565.
a Therefore, values of the shift control variables are reset to values of the 0, 40 shift control variables of a correspondent atmospheric pressure range in which 0 the detected atmospheric pressure Pa lies, the correspondent atmospheric pressure range being selected from the plurality of atmospheric pressure ranges of the "high altitude range", the "intermediate altitude range", and the "low altitude range", formed on the basis of a plurality of predetermined reference atmospheric pressures P1 and P2.
When values of the shift control variables are reset based on the detected atmospheric pressure Pa at step S540, the TCU 450 determines, on the basis of the reset values, whether an upward shifting speed is needed at step S570.
If the vehicle driving altitude is changed., .for example, from the "low altitude range" to the "intermediate altitude range", the values to be used for the shift control variables are also changed, and therefore, the amount of modification in an upward shift-pattern on a slope is also changed because the shift control variables of which the values are changed' include-shift control variables related to the modification-of the upward shift-pattern. Accordingly, occurrence of the lift-foot-up shift is changed according to the vehicle driving altitude.
If- itis determined that an upward shifting speed is 'needed-at step S570,'the:,TCU 450 performs the.:upward shifting accordinrg to a 15 predetermined up-shifting method of the prior art at step S575.
The, TCU 450 also determines whether a kick-down shift condition is satisfied at step S580. Whether the kick-down shift condition is satisfied may be determined upon whether a change of the throttle valve open-angle causes the vehicle driving state to cross over the threshold line of a downward shift-pattern.
If the kick-down shift condition is determined not being satisfied at step S580, the shift control method according to the present invention terminates.
If the kick-down shift condition is determined to be satisfied at step S580, the TCU 450 performs an accordingly determined downshift based on the reset values of the shift control variables at steps of S585 and S590.
For the accordingly determined downshift, the TCU 450 reads -values .from the register to find which altitude-range the.vehicl.e.is. being driven in and reads values of the shift control variables corresponding to the found altitude range at step S585, and performs the kick-down shift ot:tol based on the read values of the shift control.-variables at step S590.
o As described above, according to the preferred- embodiment of the present invention, relative hydraulic pressure affected by. changes of engine power caused by changes of vehicle. driving altitude is c--'-.."'considered for kick-down shifting and therefore shift, shockin kick-down 0 shiiftirig at a high altitude is reduced. Furthermore, an amount of modification of an upward shift- .pattern on a slope is also dependent on the vehicle.driving altitude and therefore frequent shifting on a slope in a high-altitude is prevented, which increases durability of an automatic transmission and provides more stability in a driving performance of a vehicle.
While the present invention has been described in detail with reference to the preferred embodiment, those skilled in the art will appreciate that various modifications and substitutions can be made thereto without departing from the sprit and scope of the present invention as set forth in the appended claims.

Claims (13)

1. A shift control method for an automatic transmission of a vehicle comprising: detecting atmospheric pressure; determining whether a predetermined atmospheric pressure applying condition is satisfied; and resetting values of shift control variables based on the detected atmospheric pressure when the predetermined atmospheric pressure applying condition is satisfied, wherein the shift control variables of which the values are comprise at least one of a modification limit RSU for defining a maximum amount of a modification of an upward shift-pattem, a minimum slope RSO for modifying the upward shift-pattern, and a maximum slope RS1 at which the upward shift pattern is modified by the modification limit RSU.
2. The shift control method of claim 1 wherein the values of shift control variables are reset to be appropriate for an extant atmospheric pressure range, the extant of atmospheric pressure range being selected from a plurality of atmospheric pressure ranges formed on the basis of a plurality of predetermined reference atmospheric pressures.
3. The shift control method of claim 1, further comprising determining whether an upward speed shift is necessary based on the reset values of shift control variables. o:"i
4. The shift control method of claim 1 wherein the shift control variables of which the values are reset comprise at least one of: oo :an initial release-duty Dsr for suddenly lowering a release duty for hydraulic pressure supplied to a release-element, a ramp-control slope dDr for gradually decreasing the release duty for the release-element from the initial release- duty Dsr, and a high-holding duty Dcr for holding duty at a higher level than a final duty of the ramp-control.
The shift control method of claim 4 further comprising: determining whether a predetermined kick-down shift condition is satisfied; and performing down-shift based on the reset values of shift control variables when the kick-down shift condition is satisfied. eeeo•°o
6. The shift control method of claim 4 wherein the shift control variables of which the values are reset further comprise at least one of: a low-holding duty Da for holding a low lever pressure to reduce an engaging shock of an apply-element, and a transition duty De for supplying sufficient hydraulic pressure to precent slip of the apply-element.
7. The shift control method of claim 1 wherein: the atmospheric pressure applying condition includes the automatic transmission not undergoing shifting, and the determining whether the predetermined atmospheric pressure applying condition is satisfied determines that the predetermined atmospheric pressure applying condition is not satisfied if the automatic transmission is undergoing shifting.
8. The shift control method of claim 1 wherein: the atmospheric pressure applying condition includes a change rate of a throttle valve open-angle being within a predetermined change rate range, and the determining whether the predetermined atmospheric pressure applying condition is satisfied determines that the predetermined atmospheric pressure applying condition is not satisfied if the change rate of the throttle valve open- angle is out of the predetermined change rate range.
9. The shift control method of claim 1 wherein: the atmospheric pressure applying condition includes the detected atmospheric pressure not being abnormal, the determining whether the predetermined atmospheric pressure applying condition is satisfied only if the detected atmospheric pressure is not abnormal, S- and the determining whether the predetermined atmospheric pressure applying condition is satisfied comprises resetting the detected atmospheric pressure as a predetermined atmospheric pressure if the detected atmospheric pressure is :abnormal.
10. The shift control method of claim 9 wherein the detected atmospheric pressure is determined to be abnormal when an error exists in a communication line between a transmission control unit and an atmospheric pressure detector, or when the atmospheric pressure detector is determined to be malfunctioning.
11. .A shift control method for an automatic transmission of a vehicle, said method being substantially as herein described with reference to Figs 4 and 5 of the drawings.
12.A shift control apparatus substantially as herein described with reference to Figs 4 and 5 of the drawings.
13.An automatic transmission for a motor vehicle, said transmission having a shift control apparatus as claimed in claim 13 or being operable in accordance with any one of claims 1 to 13. Dated this 12 t Day of February, 2003 HYUNDAI MOTOR COMPANY By: HODGKINSON OLD McINNES Patent Attomeys for the Applicant r rr r R''
AU93414/01A 2000-11-30 2001-11-23 A shift control method for an automatic transmission of a vehicle Ceased AU759923B2 (en)

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KR10-2000-0071895A KR100373038B1 (en) 2000-11-30 2000-11-30 Method for controlling kick down at high ground of automatic transmission
KR00-71895 2000-11-30
KR01-32822 2001-06-12

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FR2910100A1 (en) * 2006-12-18 2008-06-20 Renault Sas METHOD FOR CONTROLLING A CONTINUOUSLY VARIABLE AUTOMATIC TRANSMISSION FOR A MOTOR VEHICLE.

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US5269203A (en) * 1989-10-26 1993-12-14 Jatco Corporation Control system for automotive automatic power transmission with feature of atmospheric pressure dependent shift pattern selection and line pressure control
US5484350A (en) * 1993-08-31 1996-01-16 Honda Giken Kogyo Kabushiki Kaisha Control system for vehicle automatic transmission
EP0730110A2 (en) * 1995-03-03 1996-09-04 Mitsubishi Denki Kabushiki Kaisha Speed change control unit for an automatic transmission

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JP2000104576A (en) * 1998-09-28 2000-04-11 Hitachi Ltd Power transmission device for automobile and control method therefor

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US5269203A (en) * 1989-10-26 1993-12-14 Jatco Corporation Control system for automotive automatic power transmission with feature of atmospheric pressure dependent shift pattern selection and line pressure control
US5484350A (en) * 1993-08-31 1996-01-16 Honda Giken Kogyo Kabushiki Kaisha Control system for vehicle automatic transmission
EP0730110A2 (en) * 1995-03-03 1996-09-04 Mitsubishi Denki Kabushiki Kaisha Speed change control unit for an automatic transmission

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2910100A1 (en) * 2006-12-18 2008-06-20 Renault Sas METHOD FOR CONTROLLING A CONTINUOUSLY VARIABLE AUTOMATIC TRANSMISSION FOR A MOTOR VEHICLE.
WO2008074948A1 (en) * 2006-12-18 2008-06-26 Renault S.A.S Method for controlling a continuously variable automatic transmission for a motor vehicle

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AU9341401A (en) 2002-06-20
KR100373038B1 (en) 2003-02-15

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