Title of Invention

"SHIFT CONTROL SYSTEM FOR AUTOMATIC TRANSMISSION"

Abstract A shift control system is provided that comprises a vehicle speed sensor for detecting a vehicle speed and outputting a corresponding signal; a throttle position sensor for detecting an opening angle of a throttle valve and outputting a corresponding signal; and a transmission control unit for determining a target speed on the basis of signals input from the vehicle speed sensor and the throttle position sensor, and generating a corresponding shift signal, wherein the transmission control unit generates instructions for generating a first shift signal for shifting to a target shift speed on the basis of signals of the vehicle speed sensor and the throttle position sensor; instructions for detecting a shift signal generated within a predetermined period from the generation of the first shift signal, and determining if a number of shift signals generated is greater than or equal to a predetermined number; instructions for withholding synchronization according to the current shift signal, and determining if synchronization according to a previous shift signal has been terminated, if it is determined that the number of shift signals generated is greater than or equal to the predetermined number; and instructions for performing synchronization according to the current shift signal after the synchronization according to the previous shift signal has been terminated.
Full Text SHIFT CONTROL SYSTEM FOR AUTOMATIC TRANSMISSION
FIELD OF THE INVENTION
The present invention relates to an automatic transmission, and more particularly, to a shift control system in which if a number of shift signals

generated within a predetermined time period is greater than or equal to a predetermined number, a shift according to the shift signal after the predetermined number is performed only after a shift according to the previous shift signal has been performed, in order to decrease shift shock. BACKGROUND OF THE INVENTION
Generally, an automatic transmission determines a target speed on the basis of a shift map using vehicle speed and throttle opening angle as parameters and performs hydraulic pressure duty control in order to operate specific engaging members, and thereby gear shifting is automatically performed.
However, if a significant number of shift signals are continuously generated because of frequent depressions of an accelerator pedal in a short time period, a new shift signal is generated before a shift according to a previous shift signal has been terminated, and therefore the shift operation according to the previous shift signal stops and a new shift operation according to the new shift signal is performed. Consequently, frequent changes of the target speed in the automatic transmission cause the hydraulic pressure to be incorrectly routed so that shift shock occurs.

SUMMARY OF THE INVENTION
The present invention has been made in an effort to solve the above problems.
In a preferred embodiment of the present invention, the shift control system for an automatic transmission comprises:
a vehicle speed sensor for detecting a vehicle speed and outputting a corresponding signal;
a throttle position sensor for detecting an opening angle of a throttle valve and outputting a corresponding signal; and
a transmission control unit for determining a target speed on the basis of signals input from the vehicle speed sensor and the throttle position sensor, and generating a corresponding shift signal,
wherein the transmission control unit generates
instructions for generating a first shift signal for shifting to a target shift speed on the basis of signals of the vehicle speed sensor and the throttle position sensor;
instructions for detecting a shift signal generated within a predetermined period from the generation of the first shift signal, and determining if a number of shift signals generated is greater than or equal to a predetermined number;
instructions for withholding synchronization according to the current shift signal, and determining if synchronization according to a previous shift signal has been terminated, if it is determined that the number of the shift signals generated is greater than or equal to the predetermined number; and
instructions for performing synchronization according to the current shift

signal after the synchronization according to the previous shift signal has been terminated.
It is preferable that the transmission control unit further generates instructions for performing the synchronization according to the current shift signal if the number of shift signals generated is smaller than the predetermined number, and the predetermined number is 3.
It is also preferable that the predetermined period is determined based on a target speed determination history of the shift signals generated before the current shift signal. BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention, where:
FIG. 1 is a block diagram of a shift control system according to the present invention;
FIG. 2 is a flow chart showing a shift control method according to the present invention; and
FIG. 3 shows a shift control pattern in the shift control method according the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIG. 1, the shift control system according to the present invention includes a vehicle speed sensor 10, a throttle position sensor 20, an

engine speed sensor 30, a transmission control unit 40, a memory 50, and an actuator 60.
The vehicle speed sensor 10 calculates a current vehicle speed using a speed of a transfer driven gear of an automatic transmission, and outputs a corresponding electrical signal.
The throttle position sensor 20 detects a change rate of a position of a throttle valve that works together with an accelerator pedal, and outputs a corresponding electrical signal.
The engine speed sensor 30 detects an engine speed by a calculation of a crankshaft speed, and outputs a corresponding electrical signal.
The memory 50 comprises a shift pattern map using a vehicle speed and a throttle opening as parameters.
The transmission control unit 40 determines a target speed from the shift pattern map of the memory 50 using the detected throttle opening angle and the detected vehicle speed, and generates a corresponding shift signal for shifting to the determined target speed.
At this time, if a number of shift signals generated within a predetermined time period is greater than or equal to a predetermined number, for example 3, because of frequent changes of the throttle opening, a shift according to a shift signal generated after the predetermined number is performed only after a shift according to the previous speed shifting has been terminated. If the predetermined number is 3, a shift according to the third shift signal is performed only after the shift according to the second shift signal is terminated, and a shift according to a fourth shift signal is performed only after a

shift according to a third shift signal is terminated.
The actuator 60 is operated according to the signal input from the transmission control unit 40, and regulates the hydraulic pressure duty such that shift synchronization for the target speed is performed.
Referring FIG. 2, the shift control method according to the present invention will be explained hereinafter.
The transmission control unit 40 determines if a speed change is demanded on the basis of the change rate of the throttle opening of the throttle valve that works together with the accelerator pedal, while a vehicle is running (S101 andS102).
If the transmission control unit 40 determines that the demand for a speed change is needed because of the change rate of the throttle opening, the transmission control unit 40 determines a target speed from the shift pattern map stored in the memory 50, and the transmission control unit 40 then generates a corresponding shift signal and transmits the shift signal to the actuator 60 in order to control the hydraulic pressure duty such that a gear shift to the target speed is performed, and starts a timer (S103).
The transmission control unit 40 then determines whether a new shift signal for shifting to a new target speed is generated within a predetermined time period after starting the timer(S104), and if it is not, synchronization for the shift to the demanded target speed is maintained.
If it is determined that the new shift signal has been generated, the transmission control unit 40 determines if a number of shift signals generated is greater than or equal to the predetermined number (S105).

If the new shift signal is generated after the predetermined period, the actuator 60 is operated by the shift signal such that a speed shift to the target speed is performed. On the other hand, if it is determined that the number of shift signals generated within the predetermined time period is greater than or equal to the predetermined number, the transmission control unit 40 withholds synchronization to the target speed of the new shift signal(S106), and determines whether synchronization to the speed shift according to the previous shift signal has been terminated (S107). For an example, if the predetermined number is 3 and a third shift signal is generated within the predetermined time period, the transmission control unit 40 determines whether the synchronization for the speed shift according to the second shift signal before the speed shift according to the third shift signal is performed.
Then, after the synchronization for the speed shift according to the previous shift signal has been terminated, the transmission control unit 40 performs hydraulic pressure duty control in order to perform synchronization for the speed shift according to the new shift signal (S108). For an example, if the predetermined number is 3, the synchronization for the speed shift according to the third shift signal is performed only after synchronization for the speed shift according to the second shift signal has been terminated.
The predetermined period is preferably determined on the basis of the target speed determination history before the current shift signal.
For an example, if a first shift signal is a 4-2 kickdown shift signal, a second shift signal is a 2-4 lift-foot-up shift signal, and a third shift signal is a 4-2 kickdown shift signal, the predetermined period is determined considering a

time period for terminating the 4-2 and 2-4 shifts. In this case, the predetermined period can be set as 2-3 seconds. On the other hand, if a first shift signal is a 4-1 kickdown shift signal, a second shift signal is a 1-4 lift-foot-up shift signal, and a third shift signal is a 4-1 kickdown shift signal, the predetermined period is determined considering a time period for terminating the 4-1 and 1-4 shifts. In this case, the predetermined period can be set as 3-4 seconds, because the time period for terminating the 4-1 and 1-4 shifts is generally longer than that for terminating the 4-2 and 2-4 shifts.
As shown in FIG. 3, a current shift speed is maintained as 'a' while a throttle opening is A%, and a shift speed is changed from 'a' to 'b', if a throttle opening is changed from A% to B%. Then, if the throttle opening is changed from B% to C% because of the operation of the accelerator pedal, the target speed is determined as 'c' and hydraulic duty control for synchronization to the target shift speed 'c' is performed.
If the a target speed is changed from 'c' to 'd' because of the throttle opening change from C% to D% by releasing the accelerator pedal within a predetermined time period t1, synchronization for the speed shift to 'd' is performed only after synchronization for the speed shift to 'c' has been terminated as shown in the drawing.
As stated above, in the shift control method according to the present invention, if the number of shift signals generated is greater than or equal to the predetermined number within the predetermined period, synchronization for the speed shift according to the shift signal after the predetermined number is performed only after synchronization for the speed shift according to the previous shift signal has been performed, and thereby incorrect routing of the hydraulic pressure can be prevented so that shift shock can be decreased.
Although preferred embodiment of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the sprit and scope of the present invention, as defined in the appended claims.












I/We claim:
1. A shift control system for an automatic transmission comprising:
a vehicle speed sensor (10) for detecting a vehicle speed and outputting a corresponding signal;
a throttle position sensor (20) for detecting an open angle of a throttle valve and outputting a corresponding signal; characterized in that
a transmission control unit (40) for determining a target speed on the basis of signals input from the vehicle speed sensor (10) and the throttle position sensor (20), and generating a corresponding shift signal, said transmission control unit (40)
generates a first shift signal for shifting to a target shift speed;
instructions for detecting a shift signal generated within a predetermined period from the generation of the first shift signal, and determining if a number of shift signals generated is greater than or equal to a predetermined number;
withholds synchronization according to the current shift signal, and determining if synchronization according to a previous shift signal has been terminated, if it is determined that the number of shift signals generated is greater than or equal to the predetermined number; and
performs synchronization according to the current shift signal after the synchronization according to the previous shift signal has been terminated.
2. The system as claimed in claim 1, wherein the predetermined number is 3.
3. The system as claimed in claim 1, wherein the predetermined period is determined based on a target speed determination history of the shift signals generated before the current shift signal.
4. A shift control system as claimed in claim 1, wherein said control unit determines whether a number of shift signals generated within a predetermined time period is greater than or equal to a predetermined number, and permits a shift according to a shift signal that exceeds the predetermined number within the predetermined time period to be performed only after a shift according to a previous shift signal is performed.

5. The shift control system as claimed in claim 1, comprising a memory containing a shift pattern map and said transmission control unit is programmed to determine the target speed based on said map.


Documents:

538-del-2002-Abstract-(21-12-2010).pdf

538-del-2002-abstract.pdf

538-DEL-2002-Claims-(08-06-2010).pdf

538-del-2002-Claims-(16-12-2010).pdf

538-del-2002-Claims-(21-12-2010).pdf

538-del-2002-claims.pdf

538-DEL-2002-Correspondence-Others (29-10-2009).pdf

538-DEL-2002-Correspondence-Others-(08-06-2010).pdf

538-del-2002-Correspondence-Others-(16-12-2010).pdf

538-del-2002-Correspondence-Others-(21-12-2010).pdf

538-del-2002-correspondence-others.pdf

538-del-2002-correspondence-po.pdf

538-del-2002-Description (Complete)-(21-12-2010).pdf

538-del-2002-description (complete).pdf

538-del-2002-drawings.pdf

538-del-2002-form-1.pdf

538-del-2002-Form-13-(16-12-2010).pdf

538-del-2002-form-18.pdf

538-del-2002-form-2.pdf

538-DEL-2002-Form-3 (29-10-2009).pdf

538-del-2002-form-3.pdf

538-del-2002-form-5.pdf

538-del-2002-GPA-(21-12-2010).pdf

538-del-2002-gpa.pdf

538-del-2002-Petition 137-(16-12-2010).pdf

538-del-2002-Petition 138-(16-12-2010).pdf


Patent Number 245476
Indian Patent Application Number 538/DEL/2002
PG Journal Number 03/2011
Publication Date 21-Jan-2011
Grant Date 20-Jan-2011
Date of Filing 07-May-2002
Name of Patentee HYUNDAI MOTOR COMPANY
Applicant Address 231, YANGJAE-DONG, SEOCHOO-KU, SEOUL, KOREA.
Inventors:
# Inventor's Name Inventor's Address
1 KIM JOUNG-CHUL 320,655-5, IL-DONG, ANSAN-CITY, KYUNGKI-DO, KOREA.
PCT International Classification Number B60K 31/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2001-0074444 2001-11-28 Republic of Korea